Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, or ethylene cracking tar.
Carbon black is a form of paracrystalline carbon that has a high surface-area-to-volume ratio, albeit lower than that of activated carbon.
It is dissimilar to soot in its much higher surface-area-to-volume ratio and significantly lower (negligible and non-bioavailable) polycyclic aromatic hydrocarbon (PAH) content.
However, carbon black is widely used as a model compound for diesel soot for diesel oxidation experiments.
Carbon black is mainly used as a reinforcing filler in tires and other rubber products. In plastics, paints, and inks, carbon black is used as a color pigment.
Carbon black, although consisting essentially of elementary carbon is usually grouped with the inorganic pigments, and is the generic name for a wide variety of finely divided carbonaceous pigments produced by the partial combustion or thermal decomposition of liquid or gaseous hydrocarbon feedstocks under controlled conditions.
The most important are derived from natural gases and are classified as channel or furnace blacks according to the method of production.
Carbon Black is a black pigment that has been used in a wide range of fields such as newspaper ink, printing ink, colored resin, paint, toner, colored paper, India ink, and ceramics.
Various grades of carbon blacks are available ranging from all- purpose grade to high-grade. In addition, our line of products includes industrial and environmentally-friendly carbon blacks.
Carbon black is a fine particle carbon pigment obtained as soot from the incomplete combustion of many different types of organic materials, such as fruit pits, vine stalks, husks, bone, ivory, cork, resins, natural gas, or oil.
Carbon black pigments have been used since ancient times.
The carbon is collected as the charcoal residue, or in the case of Lampblack, as the smoke residue.
Carbon black is usually a fine, soft, black powder, but some blacks contain mineral impurities and tarry hydrocarbons that give it a bluish, reddish or brownish tinge.
It is very stable and unaffected by light, acids and alkalis. It absorbs ultraviolet radiation and has very good hiding properties.
Carbon black has poor drying properties in oil paints, but is commonly used in printing and lithograph inks and in Chinese ink sticks.
In industry, carbon black is used as a filtration material and a filler/pigment in coatings, rubber, plastics, paints, carbon paper, and crayons.
As a filler, carbon black increases resistance to abrasion and adds electrical conductivity. About one fourth of the weight of a standard automobile tire is carbon black.
Carbon Black is used in rubber pastes to develop mechanical features, increase rigidness and give black color.
Carbon black is the generic name for a family of small-size, mostly amorphous, or paracrystalline carbon particles grown together to aggregates of different sizes and shapes and is a modification of carbon with high surface area-to-volume ratio.
Carbon black is formed in the gas phase by the thermal decomposition of hydrocarbons from various sources and in that way is industrially manufactured in the form of hundreds of defined commercial grades that vary in their primary particle size, aggregate size and shape, porosity as well as surface area and chemistry.
The properties can be precisely controlled by varying the process type and process conditions.
This distinguishes carbon black from other forms of soot being the term for mostly undesired, sometimes hazardous solid carbon by-products from the uncontrolled combustion of carbonaceous material.
Carbon black is mainly used as a reinforcing filler in tires and other rubber products
Acetylene black; Channel black; Furnace black; Lamp black; Thermal black; C.I. Pigment Black 6
CAS Number: 1333-86-4
EC Number: 215-609-9
E number: E152 (colours)
Molar mass: 12.011 g·mol−1
Appearance: Black solid
Density: 1.8-2.1 g/cm3 (20 °C)
Solubility in water: Practically insoluble
Paint (high quality, intermediate quality, all-purpose paint, toning paint)
Printing inks (commercial offset lithographic ink, newspaper ink, photogravure ink, water-color ink)
Colored resin (polyolefin, styrene resin, vinyl chloride, engineering plastics)
Prevention of ultraviolet induced degradation
Lethal dose or concentration (LD, LC):
LD50 (median dose) > 15400 mg/kg (oral rat)
3000 mg/kg (dermal, rabbit)
The most common use (70%) of carbon black is as a pigment and reinforcing phase in automobile tires.
Carbon black also helps conduct heat away from the tread and belt area of the tire, reducing thermal damage and increasing tire life.
About 20% of world production goes into belts, hoses, and other non-tire rubber goods.
The balance is mainly used as a pigment in inks, coatings and plastics.
Carbon black is added to polypropylene because it absorbs ultraviolet radiation, which otherwise causes the material to degrade.
Carbon black particles are also employed in some radar absorbent materials, in photocopier and laser printer toner, and in other inks and paints. The high tinting strength and stability of carbon black has also provided use in coloring of resins and films. Carbon black has been used in various applications for electronics. A good conductor of electricity, carbon black is used as a filler mixed in plastics, elastomer, films, adhesives, and paints. It is used as an antistatic additive agent in automobile fuel caps and pipes.
Carbon black from vegetable origin is used as a food coloring, known in Europe as additive E153.
It is approved for use as additive 153 (Carbon blacks or Vegetable carbon) in Australia and New Zealand but has been banned in the US.
The color pigment carbon black has been widely used for many years in food and beverage packaging.
It is used in multi-layer UHT milk bottles in the US, parts of Europe and Asia, and South Africa, and in items like microwavable meal trays and meat trays in New Zealand.
The Canadian Government's extensive review of carbon black in 2011 concluded that carbon black could continue to be used in products – including food packaging for consumers – in Canada. This was because “in most consumer products carbon black is bound in a matrix and unavailable for exposure, for example as a pigment in plastics and rubbers” and “it is proposed that carbon black is not entering the environment in a quantity or concentrations or under conditions that constitute or may constitute a danger in Canada to human life or health.”
Within Australasia, the color pigment carbon black in packaging must comply with the requirements of either the EU or US packaging regulations.
If any colorant is used, it must meet European partial agreement AP(89)1.
Total production was around 8,100,000 metric tons (8,900,000 short tons) in 2006.
Global consumption of carbon black, estimated at 13.2 million metric tons, valued at US$13.7 billion, in 2015, is expected to reach 13.9 million metric tons, valued at US$14.4 billion in 2016.
Global consumption is forecast to maintain a CAGR (compound annual growth rate) of 5.6% between 2016 and 2022, reaching 19.2 million metric tons, valued at US$20.4 billion, by 2022.
Reinforcing carbon blacks
The highest volume use of carbon black is as a reinforcing filler in rubber products, especially tires.
While a pure gum vulcanization of styrene-butadiene has a tensile strength of no more than 2 MPa and negligible abrasion resistance, compounding it with 50% carbon black by weight improves its tensile strength and wear resistance as shown in the table below.
It is used often in the aerospace industry in elastomers for aircraft vibration control components such as engine mounts.
Certain types of carbon black used in tires, plastics and paints
ame Abbrev. ASTM
Super Abrasion Furnace SAF N110 20–25 25.2 1.35 1.25
Intermediate SAF ISAF N220 24–33 23.1 1.25 1.15
High Abrasion Furnace HAF N330 28–36 22.4 1.00 1.00
Easy Processing Channel EPC N300 30–35 21.7 0.80 0.90
Fast Extruding Furnace FEF N550 39–55 18.2 0.64 0.72
High Modulus Furnace HMF N660 49–73 16.1 0.56 0.66
Semi-Reinforcing Furnace SRF N770 70–96 14.7 0.48 0.60
Fine Thermal FT N880 180–200 12.6 0.22 –
Medium Thermal MT N990 250–350 9.8 0.18
Practically all rubber products where tensile and abrasion wear properties are important use carbon black, so they are black in color.
Where physical properties are important but colors other than black are desired, such as white tennis shoes, precipitated or fumed silica has been substituted for carbon black. Silica-based fillers are also gaining market share in automotive tires because they provide better trade-off for fuel efficiency and wet handling due to a lower rolling loss. Traditionally silica fillers had worse abrasion wear properties, but the technology has gradually improved to a point where they can match carbon black abrasion performance.
Carbon black (Color Index International, PBK-7) is the name of a common black pigment, traditionally produced from charring organic materials such as wood or bone.
It appears black because it reflects very little light in the visible part of the spectrum, with an albedo near zero.
The actual albedo varies depending on the source material and method of production.
It is known by a variety of names, each of which reflects a traditional method for producing carbon black:
Ivory black was traditionally produced by charring ivory or bones (see bone char).
Vine black was traditionally produced by charring desiccated grape vines and stems.
Lamp black was traditionally produced by collecting soot from oil lamps.
All of these types of carbon black were used extensively as paint pigments since prehistoric times.
Rembrandt, Vermeer, Van Dyck, and more recently, Cézanne, Picasso and Manet employed carbon black pigments in their paintings.
A typical example is Manet's "Music in the Tuileries", where the black dresses and the men's hats are painted in ivory black.
Newer methods of producing carbon black have largely superseded these traditional sources.
For artisanal purposes, carbon black produced by any means remains common.
Surface and surface chemistry
All carbon blacks have chemisorbed oxygen complexes (i.e., carboxylic, quinonic, lactonic, phenolic groups and others) on their surfaces to varying degrees depending on the conditions of manufacture.
These surface oxygen groups are collectively referred to as volatile content.
It is also known to be a non-conductive material due to its volatile content.
The coatings and inks industries prefer grades of carbon black that are acid-oxidized.
Acid is sprayed in high-temperature dryers during the manufacturing process to change the inherent surface chemistry of the black.
The amount of chemically-bonded oxygen on the surface area of the black is increased to enhance performance characteristics.
Carbon black is considered possibly carcinogenic to humans and classified as a Group 2B carcinogen because there is sufficient evidence in experimental animals with inadequate evidence in human epidemiological studies.
The evidence of carcinogenicity in animal studies comes from two chronic inhalation studies and two intratracheal instillation studies in rats, which showed significantly elevated rates of lung cancer in exposed animals.
An inhalation study on mice did not show significantly elevated rates of lung cancer in exposed animals.
Epidemiologic data comes from three cohort studies of carbon black production workers.
Two studies, from the United Kingdom and Germany, with over 1,000 workers in each study group showed elevated mortality from lung cancer.
A third study of over 5,000 carbon black workers in the United States did not show elevated mortality.
Newer findings of increased lung cancer mortality in an update from the UK study suggest that carbon black could be a late-stage carcinogen.
However, a more recent and larger study from Germany did not confirm this hypothesis.
There are strict guidelines available and in place to ensure employees who manufacture carbon black are not at risk of inhaling unsafe doses of carbon black in its raw form.
Respiratory personal protective equipment is recommended to properly protect workers from inhalation of carbon black.
The recommended type of respiratory protection varies depending on the concentration of carbon black used.
People can be exposed to carbon black in the workplace by inhalation and contact with the skin or eyes.
The Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for carbon black exposure in the workplace at 3.5 mg/m3 over an 8-hour workday.
The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 3.5 mg/m3 over an 8-hour workday.
At levels of 1750 mg/m3, carbon black is immediately dangerous to life and health.
PIGMENT CARBON BLACKS
Using Carbon Black for pigment purposes, is a technique that has been used by humans since the early civilizations.
Initially, carbon black was only used to color inks, but this technique has been further developed to this day.
Specifically with colors, it is very important to reach the exact shade of black.
In many applications Carbon Black is used as a black pigment, to achieve a spectrum ranging from gray to deep black.
With the modification of different carbon black properties it is possible to reach specific required properties for the final product like tinting strength, blackness, viscosity, shade, UV-resistance and dispersability.
The majority of pigment carbon blacks are produced in the furnance carbon black process, as this production process allows the biggest possibilities to vary the 3 main properties of carbon black: primary particle size, surface area and the structure of carbon black tailored to the desired application.
New ink, coating and polymer formulations continously increase the performance requirements of Carbon blacks.
Lamp black is also popular due to ist bluish undertone
The bluish undertone is very popular in the production of a black or gray color, because of the many-faceted variations that result from it.
Pigment carbon blacks are usually grouped with the inorganic pigments.
Carbon black is composed of fine particles consisting mainly of carbon.
Various features of carbon black are controlled in production by partially combusting oil or gases.
Carbon black is widely used in various applications from black coloring pigment of newspaper inks to electric conductive agent of high-technology materials.
Soot, which is similar to carbon black, was used for writing letters on papyrus in ancient Egypt and on bamboo strips in ancient China.
Carbon black production became a type of cottage industry about the time when the paper production method was established in the second century.
It then became widely used in industries after it was produced with the channel process in 1892 and with the oil furnace method in 1947.
Application of carbon black
A large amount of carbon black is used mainly in tires as excellent rubber reinforcement.
Carbon black is also an excellent coloring agent as black pigment, and therefore is widely used for printing inks, resin coloring, paints, and toners.
Furthermore, carbon black is used in various other applications as an electric conductive agent, including antistatic films, fibers, and floppy disks.
Carbon black was used as a pigment since very earliest times.
Carbon blacks are made by heating wood, or other plant material, with a very restricted air supply.
Sticks of charcoal have been used for sketching by artists of all periods, and traces of their work may be found on the ground layer of paintings.
Carbon black was used both in oil and watercolour.
Carbon black is used today in photocopier and laser printer toner.
Carbon black is easy to prepare and has excellent hiding power.
Carbon black is just a common name for a black pigment, traditionally produced from charring organic materials such as wood.
There are lots of varieties of names, each of which reflects a traditional method for producing a particular kind of carbon black.
The most important are:
Vine black was traditionally produced by charring desiccated grape vines and stems.
Lamp black was traditionally produced by collecting soot, also known as lampblack, from oil lamps.
Names for Carbon black:
Alternative names: Charcoal black, vine black, lamp black
Word origin: The name "Carbon black" comes from Latin carbo = charcoal.
German French Italian
Pflanzenschwarz noir de charbon nero carbone (carbon black), nero di lampada (lamp black), nero di vite (vine black)
Origin: plant & artificial
Chemical name: Amorphous carbon
Carbon black, any of a group of intensely black, finely divided forms of amorphous carbon, usually obtained as soot from partial combustion of hydrocarbons, used principally as reinforcing agents in automobile tires and other rubber products but also as extremely black pigments of high hiding power in printing ink, paint, and carbon paper.
Carbon black is also used in protective coatings, plastics, and resistors for electronic circuits.
As a reinforcing filler it greatly increases resistance to wear and abrasion.
About one fourth of the weight of a standard automobile tire is carbon black.
For tires on vehicles on which it is necessary to avoid building up an electrostatic charge, such as oil trucks and hospital operating carts, even more carbon black is added to make the rubber electrically conducting.
Carbon black is used in many products and articles we use and see around us on a daily basis, such as:
Slabs on grade
Thus, the requirements for the carbon black are different for each application and influence the specific properties in the final application.
For the coatings market, there is a wide range of carbon black grades available. This can make it difficult to choose the most suitable carbon black for your final application.
For example, when aiming for automotive paint with a blue undertone, the carbon black of choice will have a high jetness. However, normally these types of carbon black grades are the most difficult to disperse correctly into the desired particle size.
The carbon black producers are addressing these issues by developing specialty carbon black grades that have been surface-modified and/or are pre-treated to overcome these difficulties.
Key Properties of Carbon Black
Primary Particle Size
The first parameter to consider is the primary particle size of the carbon black. The primary particle size can vary from 15 nm up to 300 nm. Some furnace blacks have a particle size of even as small as 8 nm.
Primary Particle Size of Carbon Black
Small particles result in higher jetness caused by a high surface area. They also provide:
On the downside, the smaller particle sizes lead to higher viscosity and require more energy for dispersing. These types generally have a blueish undertone and are used in the automotive industry where high jetness is required.
Whereas, the higher particle sizes improve the viscosity and dispersibility properties within the application. They have a more brownish undertone and are generally more suitable for the rubber and tire applications.
Already during the production process, aggregates are being formed from the primary particles. The structure of the carbon black is determined by:
How the aggregates are shaped?
The level of branches in the aggregates.
Another important aspect of carbon black is surface chemistry. Depending on the production process, the functional groups on the surface of the carbon black will be different. The type and amount of functional groups will play a big role in the affinity within the application it is being used.
In general, when talking about surface chemistry, it is meant the level of oxygen-containing groups on the surface. For certain applications, the carbon black is further oxidized to increase the amount of oxygen-containing groups on the surface.
Specifically, in ink and coating applications, this will be beneficial to improve the dispersibility, pigment wetting, rheology and overall performance in the selected system.
Tint strength is the ratio, expressed as tint units, of the reflectance of a standard paste to a sample paste, both prepared and tested under specified conditions.
As described in the test method ASTM D 3265-19b, a carbon black- zinc oxide paste is prepared, either by using an automatic muller apparatus or the Speedmixer® (DAC 150 FVZ).
For the preparation of the carbon black-zinc oxide paste, pre-determined raw materials are being used, such as:
Industry tint reference black (ITRB2)
A specific zinc oxide (lot number 11), and
Greenflex ESO (epoxidized soybean oil)3
The reference paste is set as 100, and all the carbon blacks used are compared to this paste. This means when carbon black has a tinting strength of 80, it will give a less black color when using the same amount.
JetnessThe jetness (Mc) is the color-dependent black. It is indicatively measured as b* using a colorimeter (where b* is directly related to the L-value) and is not to be confused with blackness. The jetness is influenced directly by the primary particle size.
The lower the primary particle size, the higher the jetness.
Blackness, on the other hand, is a degree of blackness, directly related to the reflectance. In the case of high jetness pigments, it can be even below 1%.
In general, jetness is determined according to procedure DIN 55979 - determination of the black value of carbon black, where the residual reflection is measured. In this method, the blackness is used as an indication of the jetness.
The combination of blackness and jetness will tell you the undertone, where:
Blackness/Jetness Combination Color of Undertone
Blackness > Jetness Brown
Blackness = Jetness Neutral
Blackness < Jetness Blue
There are various carbon blacks in the market that can provide anti-static or conductive properties. The main properties which will influence the conductive properties of the carbon black are:
Specific surface area
Most of the conductive carbon blacks available in the market have higher surface areas and structures and can contain a significant volume of micropores.
Conductivity is measured by the surface resistivity of the conductive film presented in Ω/square or in volume resistivity of Ω-cm.
A better conductivity performance of a conductive carbon black will aid in adding the appropriate loading of carbon black to achieve the minimum required surface resistivity for the application.
Surface Resistivity in Ω/square
In the final selection, to prepare a conductive or dissipative coating, a balance in the carbon black properties has to be found. As the high surface area will give you a more conductive coating but these blacks, therefore, have a higher oil absorption number, causing more binder or wetting agents to be used for optimal dispersion, and more energy is required to disperse the carbon black to achieve the desired particle size. Next to this, the level of surface resistivity required will then determine the amount of carbon black needed.
Having learnt about the production processes and properties of carbon black, let's explore the parameters to consider while selecting the carbon black for specific coatings and ink applications.
Finding the Right Carbon Black Grade for Your Application
With regard to coating applications, we need to consider the following parameters:
Ease of use
Physical form: powder or pellets
Final requirements of application such as:
Indirect food contact
In the table below an overview is given of the different types which are available:
Type of Carbon Black Description Examples
High color Highest jetness
Raven 2800 Ultrab
EMPEROR® 2000 (for WB)a
EMPEROR® 1200 (for SB)a
Color black FW 255c
Medium color Medium-high jetness for masstone
MONARCH® 800 or 100a
Printex® F 80c
Low viscosity Provide good stability and dispersibility
Multi-purpose All-purpose grade for use in both tinting and masstone
Tinting Provide high tint strength and desired undertone
Conductive Conductive carbon black
Treated Surface oxidation to provide better dispersibility, high volatile content, acidic pH
Raven 5000 Ultra IIb
Color black FW 310c
Food contact Indirect food contact - FDA regulation
BLACK PEARLS® 4750a
Printex® F 80c
Recovered carbon black Recovered using rubber pyrolisis, high ash content
a: Cabot; b: Birla Carbon; c: Orion Engineerd Carbons; d: Black Bear; e: Mitsubishi Chemical; f: ShanDOng Emperor-Taishan Carbon; g: Spring Green
Raven by Birla Carbon
Carbon Black in Rubbers and Tires
The official classification of carbon black used in rubbers is described in ASTM D17651.
The first number indicates the particle size, where
The N100 series has the smallest having a particle size of 11-19 nm (average)
The N900 series has the largest particle size of 201-500 nm (average)
The second and third digit are arbitrary numbers but can be used to describe the functionality or structure of the carbon black.
Here, N stands for the ‘normal’ cure of a rubber compound.
The channel carbon blacks were (predominantly) slow curing, and these grades of carbon black were indicated with the S prefix.
In tires, mainly types from N115 to N375 are being used, and all have a specific contribution to the final performance of the tire.
For the liners within tires, the carbon blacks with a larger particle size from N660 to N990 are being used.
For technical rubbers, in general, the larger particle sizes are used starting at N550 with specific addition of N3030.
Carbon Black in Plastics
In plastics, the carbon black provides three main properties:
The carbon blacks are used to produce masterbatches that are further used in the final preparation of the plastics. During the production of the masterbatch, the carbon black must have good tinting properties, resulting in the desired color with minimal use of carbon black with good dispersibility, ensuring low energy needed to provide good dispersion of the carbon black.
When the masterbatch is used in the final application, the carbon black must spread easily from the base polymer to create an even result, good dilutability.
Food Contact Regulation
For certain applications, specialty carbon blacks are needed which comply with the food contact regulations as set by the FDA (The U.S. Food & Drug Administration).
The applicable purity requirements for compliance with U.S. FDA regulations are:
Total PAHs should not exceed 0.5 ppm
Benzo(a)pyrene should not exceed 5.0 ppb
As a result of a new Food Contact Notification (FCN) submitted by Cabot to FDA (FCN 1789), FDA-compliant specialty carbon blacks can be used as a colorant for polymers with no specified upper limit.
The Commission Regulation EU No. 10/2011 is applicable in all the countries of the European Union.
The purity requirements and specifications for compliance are:
Toluene extract ≤ 0.1%2
Cyclohexane extinction at 386 nm < 0.02 for 1 cm cell or < 0.1 for 5 cm cell
Benzo(a)pyrene ≤ 0.25 mg/kg (250 ppb)
Primary particles of 10-300 nm, Aggregates of 100-1200 nm, Agglomerates 300nm+
In the final food contact item, a maximum of 2.5% carbon black by weight is allowed
Carbon Black is a commercial form of solid carbon that is manufactured in highly controlled processes to produce specifically engineered aggregates of carbon particles that vary in particle size, aggregate size, shape, porosity and surface chemistry. Carbon Black typically contains more than 95 % pure carbon with minimal quantities of oxygen, hydrogen and nitrogen.
In the manufacturing process, Carbon Black particles range from 10 nm to approximately 500 nm in size. These fuse into chain-like aggregates, which define the structure of individual Carbon Black grades.
What is Carbon Black
Carbon Black is used in a diverse group of materials in order to enhance their physical, electrical and optical properties. Its largest volume use is as a reinforcement and performance additive in rubber products.
In rubber compounding, natural and synthetic elastomers are blended with Carbon Black, elemental sulphur, processing oils and various organic processing chemicals, and then heated to produce a wide range of vulcanized rubber products. In these applications, Carbon Black provides reinforcement and improves resilience, tear-strength, conductivity and other physical properties.
Carbon Black is the most widely used and cost effective rubber reinforcing agent (typically called Rubber Carbon Black) in tire components (such as treads, sidewalls and inner liners), in mechanical rubber goods (“MRG”), including industrial rubber goods, membrane roofing, automotive rubber parts (such as sealing systems, hoses and anti-vibration parts) and in general rubber goods (such as hoses, belts, gaskets and seals).
Applications of Carbon Black
Besides rubber reinforcement, Carbon Black is used as black pigment and as an additive to enhance material performance, including conductivity, viscosity, static charge control and UV protection. This type of Carbon Black (typically called Specialty Carbon Black) is used in a variety of applications in the coatings, polymers and printing industries, as well as in various other special applications.
Actually, after oil removal and ash removal processing from tire pyrolysis, we can get high-purity commercial carbon black, which can be used to make color masterbatch, color paste, oil ink and as addictive in plastic and rubber products. Besides, after activation treatment, the carbon black will become good materials to produce activated carbon.
In the coatings industry, treated fine particle Carbon Black is the key to deep jet black paints. The automotive industry requires the highest black intensity of black pigments and a bluish undertones.
Carbon Black has got a wide array of applications in different industries
Small particle size Carbon Blacks fulfill these requirements. Coarser Carbon Blacks, which offer a more brownish undertone, are commonly used for tinting and are indispensable for obtaining a desired grey shade or color hue.
In the polymer industry, fine particle Carbon Black is used to obtain a deep jet black color. A major attribute of Carbon Black is its ability to absorb detrimental UV light and convert it into heat, thereby making polymers, such as polypropylene and polyethylene, more resistant to degradation by UV radiation from sunlight. Specialty Carbon Black is also used in polymer insulation for wires and cables. Specialty Carbon Black also improves the insulation properties of polystyrene, which is widely used in construction.
In the printing industry, Carbon Black is not only used as pigment but also to achieve the required viscosity for optimum print quality. Post-treating Carbon Black permits effective use of binding agents in ink for optimum system properties. New Specialty Carbon Blacks are being developed on an ongoing basis and contribute to the pace of innovation in non-impact printing.
Description of pigment carbon black
Pigment Carbon black refers to the use of pigment as a colorant in paints, inks, plastics, chemical and leather chemicals
Generally divided into high, medium and low color three categories. (HCC), high pigment black (HCF), medium pigment tank black (MCC), medium pigment furnace black (MCF), ordinary pigment tank black (HCC), high pigment cell black (HCF) RCC), ordinary pigment furnace black (RCF) and low pigment furnace black (LCF). A carbon black for coloring pigments in ink, paint, paint, and the like. According to the color intensity (or blackness) and the size of the particles are generally divided into high-pigment carbon black, medium carbon black, ordinary pigment carbon black and low pigment carbon black four. Mainly by the contact method and oil furnace production.
Carbon black is one of the oldest manufactured materials. Early uses can be traced back to ancient China, the early Egyptians, and India. Early demand for carbon black was driven by the invention of the printing press in the fifteenth century. The discovery in the early nineteenth century that carbon black reinforces natural rubber and thus greatly increases the longevity of tires thrust the material into the modern age.
Today carbon black is found in all aspects of modern life. It is used in inkjet printer ink, as reinforcements for natural and synthetic rubber, as the active agent in electrically conductive plastics, and is used as a pigment and tinting-aid in paints, coatings, newspaper inks, and cosmetics. Carbon black use is ubiquitous in the modern world.
There are three significant processes for the manufacture of carbon black: the furnace process, the channel process, and the acetylene process.
The furnace process is the most prevalent by far, accounting for over 80% of total capacity. The products made by each process have unique characteristics.
For example, the acetylene process produces a carbon black with very low structure (particle complexity) and higher graphitic content than those produced by the furnace process.
The remainder of this overview will concentrate on carbon blacks manufactured by the furnace process.
Although there are differences among the multitude of processes, they all involve fuel combustion in a controlled atmosphere environment.
In the furnace process, “resid” or “decant” oils, which are low cut fractions from the oil refining process, are combusted in a controlled atmosphere at high temperatures.
Typical processing temperatures are in the range of 800C to 1200C.
The best way to envision a carbon black reactor is to imagine a very large blow torch in a ceramic tube with controlled oxygen levels.
If too much oxygen is present, soot formation takes place.
In the furnace process, fuel is atomized and sent to the reaction chamber where carbonization starts.
Oxygen levels are maintained below the level where soot formation takes place.
The atomized fuel undergoes reactions to eliminate non-carbonaceous materials, the carbon atoms then begin to bond to nearby neighbors within the droplet, starting the solidification process. It is this carbonized droplet that forms the most fundamental carbon black particle, called the “primary particle.” As the carbonizing fuel droplet leaves the reaction chamber and progresses down the path of the furnace, it may come in contact with other carbonizing droplets, and under the appropriate conditions, they bond to form a carbon black “aggregate.” The carbon black primary particles fuse to form a coalesced mass. One can view a carbon black aggregate particle as a “bunch” of grapes. Each individual grape is a primary particle and the “bunch” is the aggregate particle.
The aggregates travel down the flight of the reactor. During this flight the reaction can be quenched by water addition or temperature control.
Both are used to selectively modify the surface chemistry, size, and complexity of the aggregate particle.
After quenching, the particles travel the flight of the reactor where they are captured in bag filters or cyclones separators.
The particles at this stage are referred to as “fluffy” and have very low bulk density.
Some degree of densification is required to convert the carbon black to a more useable form. Densification can be achieved though pelletization (beading) processes, where the fluffy powder is mixed with binders or water under low sheer conditions. Various densification processes are used in the manufacturing of carbon black pellets and include vacuum rollers, pin pelletizers, and stirred tanks.
The utility and ultimate economic value of carbon black is determined through a complex mix of carbon chemistry, surface energy, and particle physics.
The most important properties include the surface area, primary particle size, structure (complexity of composition), surface chemistry, and binder chemistries used in the pelletization process.
Frequently, tradeoffs and compromises are made between desired end-use performance and the ability to disperse carbon black within a polymer matrix.
Primary Particles: The smallest unit of a carbon black particle, the primary particle, has properties of size, graphitic content, shape, and crystallinity.
Although the majority of processes manufacture near-spherical shaped primary particles, some processes produce primary particles having aspect ratios higher than those of true spheres.
The higher aspect ratio leads to higher surface area per unit volume and provides more wettable surface area, improving ease of dispersion and increasing electrical conductivity.
Primary particle attributes influence color, electrical conductivity, and UV blocking performance of the carbon black.
Aggregates: Carbon black aggregates are complex clusters of fused primary particles.
Aggregates have dimensions of size, shape, void volume, and structure. Each of these dimensions determine the ultimate utility of the carbon black and provides competitive grade differentiation among carbon black manufacturers.
The size of the aggregate influences the color aspect of the carbon black and its tinting strength.
The shape and structure influence dispersability and to some extent electrical conductivity.
Void volume influences wettability and is a critical concern in applications where the carbon black will be used in a liquid medium such as a coating, paint, or ink.
Inter-particle Attractions and Agglomerates: Carbon black particles are small. For example, large aggregates are the size of red blood cells and aggregates composed of small primary particles are roughly the size of a tobacco mosaic virus.
Primary particles can be as small as 5 nm and aggregates can be as small as 50 nm.
It is this small size that makes carbon black so useful in pigmentation – a little goes a long way.
The small size of carbon black and its triboelectic properties results in carbon black obeying laws of bi-polar particle physics.
Van der Waals Forces: Owing to the small size of carbon black particles, inter-particle interactions are subject to Van der Waals forces. Referring to Figure I, as the distance between two carbon black particles decreases (moving from right to left on the ordinate scale of Figure I) the repulsive forces decrease, represented by negative potential energy Eµ, until they reach the maximum attraction at the minimum of the potential well (the valley on the abscissa axis.) Moving the particles closer together meets with significant potential energy resistance as indicated by the sharp rise in the energy dimension on the ordinate axis. Particles trapped in the potential well are called agglomerates. Once the carbon black aggregates have agglomerated it requires energy to separate them.
The ability to break up the agglomerates into the constituent aggregates and achieve adequate dispersion is critical to achieving desirable end-use performance in many applications. A significant body of literature has been developed on the science surrounding dispersion of carbon black in various mediums, however, for industrial applications dispersion remains an art with experienced practitioners having the advantage of know how, technique, and trade secrets.
Owing to the variation of shape and size, carbon black can exhibit a range of color properties. Important color properties include jetness, mass tone, and tinting strength. The delicate interaction between primary particle size, surface area, and aggregate size determines the ultimate color. The structure influences the dispersability of carbon black and thus determines the level of color achievable in the host matrix. Carbon black is added to plastics not only to make plastics black, but also to change the tint characteristics of other colors.
Color properties of carbon black are measured using colorimeters and have values of L, a*, b*.
Typically, carbon black is compounded into the host plastic matrix at concentrations near 1-2% and then the color values are measured on a molded plack specimen.
The L value (white = 100, black = 0) measures color density, the b* value is indicative of the yellow/blue balance (positive values indicate yellow and negative values indicate blue) and the a* value is reflective of the red/green balance (positive values indicating red and negative values indicating green.)
The “L” value can be correlated to the ratio of particle size to surface area and is a useful tool for comparing competitive grades of carbon black. The b* is indicative of jetness and correlated to the L value.
Jetness. Carbon black is added to plastics to impart a black color, the measurement of which is referred to as “jetness.”
More jet blacks appear blacker than those having less jet characteristics.
Jetness is a complex function of surface area, primary particle size, and degree of dispersion.
Carbon blacks possessing smaller primary particle sizes tend to impart a higher degree of jetness than those having larger primary particles.
Trial and error has resulted in empirical relationships between the carbon black properties and jetness.
Masstone. When compounded into plastics carbon black can impart colors ranging from a bluish black to a brown/black undertone.
This color range is referred to as the masstone of the black and is strongly correlated to particle size and the scattering of light in the host plastic matrix.
Owing to differences in refractive index and light scattering for different plastics, two different plastics containing well-dispersed carbon black can have the same jetness but differ greatly in masstone.
Tinting Strength. An important property of carbon black is its ability to modify the visual appearance of other colors.
The tinting strength is a measure of the effectiveness of the carbon black.
There are a variety of methods used in measuring tinting strength but the most prevalent is ASTM D 3265.
In this method, carbon black is added to a mixture of zinc oxide in dispersion medium (soy oil for example) and the reflectance values are measured relative to the zinc oxide standard.
Tinting strength increases with decreasing primary particle size and decreases with aggregate structure complexity.
Tinting strength reaches a maximum for primary particle sizes of less than 20nm.
Carbon Black Masterbates
Carbon black manufactured by commercial processes is a complex mixture of particles.
Industrial grades of carbon black exhibit a distribution of aggregate sizes and shapes, each comprised of a distribution of different size and shaped primary particles.
Consequently, property measurements of carbon black are a statistical average around a mean value of the bulk sample.
Surface area and structure are the key properties that influence the utility and value of carbon black in many applications.
For example, surface area influences the ability of carbon black to absorb UV radiation. Structure influences the ease of dispersion and electrical conductivity properties.
It is the balance of surface area and structure that determines the utility of the particular grade of carbon black.
Surface Area Measurements: A variety of methods exist to measure surface area of carbon black, each has its unique application either in the manufacturing quality control environment or in laboratory confirmation studies.
The most prevalent methods for surface area measurement include CTAB (cetyltrimethylammonium bromide adsorption), Iodine adsorption, and Nitrogen number.
Recent advances in high resolution microscopy and inexpensive high speed computers has enabled the use of particle size analysis with automated image classification, however, this method is relegated to research labs.
The CTAB method is used primarily in laboratory environments for measuring the surface area of carbon black.
The method is described in ASTM D 3765 and essentially involves measuring the isotherm-of-adsorption of CTAB by carbon black in an aqueous dispersion.
The CTAB method is particularly relevant to the plastics market because it measures the surface area available for wetting by the plastic matrix.
This is unlike nitrogen porosity measurements that measure the surface area of excluded volume, unavailable to wetting.
In the manufacturing environment, where the target carbon black grade properties are known, the Iodine method (ASTM D 1510) is used to measure surface area.
The method is useful for quality control but is influenced by active surface chemistry, unreacted feedstock, oils and binders.
The reported iodine number should not be used as a guide for grade selection when developing a plastic compound or end use article.
Nitrogen Surface Area.
Surface area as determined by BET nitrogen absorption techniques (ASTM D3037) reflects the true surface area including occluded volume and the porosity of the carbon black primary particles.
The method is particularly useful when the carbon black will be dispersed in a liquid medium such as in ink or coating applications.
The correlation between nitrogen surface area measurements and CTAB can be used to gain insight on the porosity of the carbon black.
Porosity is an important characteristic in grade selection and quality control for inks and coatings.
Structure Measurements: The structure of carbon black influences the dispersability in plastics, electrical conductivity, and to some degree, the color of the finished article.
Structure is a measure of the complexity of the carbon black aggregate particle and reflects how the constituent primary particles are connected.
Carbon black particles vary in shape from the spherical particles found in thermal blacks to more complex chains and clustered forms common in furnace blacks.
The more complex shapes form internal voids, nooks, and crannies.
Liquid absorptive measurements are used to characterize the structure of carbon blacks.
Aggregates that are more spherical in shape adsorb less material than those exhibiting more complex shapes and having more voids.
Liquid adsorption methods provide insight on the average bulk property and do not provide information on the distribution of properties constituting the average.
The most frequently used method of characterizing the structure of carbon black is the adsorption of dibutylpthlate, DBP (ASTM 2414-90.)
The method is based on measuring the torque of carbon black powder as DBP is added.
At the point of full absorption, correlating to full surface area coverage, the mixture reaches a plasticization state and the torque rises quickly at this point the level of DBP added is recorded.
Higher levels of DBP addition correlate to higher structure.
Crushed DBP Method.
Industrially manufactured carbon black exhibits a distribution of particle sizes and shapes.
Consequently, smaller aggregates can occupy the occluded volume of larger aggregates.
Additionally, owing to Van der Waals forces, carbon black aggregates can agglomerate into clusters which can influence the DBP measurement.
Both of these phenomena reduce the apparent structure as measured by the DBP method. The crushed DBP method was developed to address these phenomena.
The method (ASTM D 3493) involves subjecting the carbon black to several cycles of high pressure, typically 165MPa, before conducting the DBP measurement.
The high pressure serves to break agglomerates and separate the particles captured in the occluded volumes of larger aggregates.
General term for the black pigment used in most printing inks. Carbon black is an amorphous (i.e., lacking a crystalline structure) form of carbon produced by partially burning hydrocarbons (such as crude oil or natural gas), wood, or animal bones and tissue, and condensing the sooty flame on a cool surface. Carbon Black pigments are 90:99% carbon, with only 1:10% volatile substances.
Carbon Black pigments vary in color from a grayish blue to jet black, are not chemically reactive, are extremely fast-to-light, and have a high resistance to heat, alkalis, acids, solvents, waxes, water, soaps, and other chemicals. Carbon Blacks are classified as Furnace Black or Channel Black, which primarily describes the difference in the means of producing the pigment. (See also Black Pigment.)
('CI Pigment Black 7 No. 77266'.)
Carbon black provides more strength, durability to tires and other rubber products
Carbon black is a black powder that is used to increase the strength of products made of rubber, like tires.
Adding carbon black extends the life of such products, thereby saving natural resources.
Thanks to extensive carbon black research and development, the latest grades have increasingly high abrasion resistance and low rolling resistance, which in turn increases fuel efficiency and curbs CO2 emissions from cars.
Carbon black is produced by injecting aromatic oils into a high-temperature reactor, where they form agglomerates of structured carbon particles.
Coal chemical aromatic oils are excellent raw materials for this process and give the highest carbon black yields.
This means less CO2 emissions for each kg of carbon black produced.
Carbon black is also used as a pigment for paints and inks.
Carbon Black is a commercial form of solid carbon that is manufactured in highly controlled processes to produce specifi cally engineered aggregates of carbon particles that vary in particle size, aggregate size, shape, porosity and surface chemistry. Carbon Black typically contains more than 95 % pure carbon with minimal quantities of oxygen, hydrogen and nitrogen. In the manufacturing process, Carbon Black particles are formed that range from 10 nm to approximately 500 nm in size. These fuse into chain-like aggregates, which defi ne the structure of individual Carbon Black grades. Carbon Black is used in a diverse group of materials in order to enhance their physical, electrical and optical properties. Its largest volume use is as a reinforcement and performance additive in rubber products. In rubber compounding, natural and synthetic elastomers are blended with Carbon Black, elemental sulfur, processing oils and various organic processing chemicals, and then heated to produce a wide range of vulcanized rubber products. In these applications, Carbon Black provides reinforcement and improves resilience, tear-strength, conductivity and other physical properties. Carbon Black is the most widely used and cost-eff ective rubber reinforcing agent (typically called Rubber Carbon Black) in tire components (such as treads, sidewalls and inner liners), in mechanical rubber goods (“MRG”), including industrial rubber goods, membrane roofi ng, automotive rubber parts (such as sealing systems, hoses and anti-vibration parts) and in general rubber goods (such as hoses, belts, gaskets and seals). Besides rubber reinforcement, Carbon Black is used as black pigment and as an additive to enhance material performance, including conductivity, viscosity, static charge control and UV protection. This type of Carbon Black (typically called Specialty Carbon Black) is used in a variety of applications in the coatings, polymers and printing industries, as well as in various other special applications. In the coatings industry, treated fi ne particle Carbon Black is the key to deep jet black paints. The automotive industry requires the highest jetness of black pigments and a bluish undertones.
Small particle size Carbon Blacks fulfi ll these requirements. Coarser Carbon Blacks, which off er a more brownish undertone, are commonly used for tinting and are indispensable for obtaining a desired gray shade or color hue. In the polymer industry, fi ne particle Carbon Black is used to obtain a deep jet black color. A major attribute of Carbon Black is its ability to absorb detrimental UV light and convert it into heat, thereby making polymers, such as polypropylene and polyethylene, more resistant to degradation by UV radiation from sunlight. Specialty Carbon Black is also used in polymer insulation for wires and cables. Specialty Carbon Black also improves the insulation properties of polystyrene, which is widely used in construction. In the printing industry, Carbon Black is not only used as pigment but also to achieve the required viscosity for optimum print quality. Post-treating Carbon Black permits eff ective use of binding agents in ink for optimum system properties. New Specialty Carbon Blacks are being developed on an ongoing basis and contribute to the pace of innovation in non-impact printing
With a yearly production volume exceeding ten million metric tons, the most important Carbon Black manufacturing process is the Furnace Black method. More than 98 % of the world’s annual Carbon Black production is manufactured through this process. Nevertheless, other manufacturing methods are also used in the commercial production of Carbon Black, e.g., for fabrication of Gas Blacks, Lamp Blacks, Thermal Blacks and Acetylene Blacks
The variety of Carbon Blacks, its production methods and possible applications show that “soot” has come a long way. Much has been published about the subject in technical journals, textbooks, reference works and product brochures. This brochure will reveal the many interesting facets of Carbon Black - a product that is both simple and sophisticated. Indeed, many of the things we take for granted in our everyday lives would not be possible without Carbon Black.
Ancient civilizations in China and Egypt mixed soot into resins, vegetable oils or tar to create colors and inks. Allowing a fl ame, usually from an oil lamp, to come in contact with a cooled surface causes soot to accumulate on the cooled surface. The soot could then be scraped off and collected as a powder. This process, referred to as the impingement process, that involves using the fl ame from an oil lamp was a precursor to today´s Lamp Black process. However it is also the basis of the Channel and Gas Black processes, which utilize gas fl ames impinging on cool cast iron channels or rotating cooled cylinders. Later on, both the Greeks and the Romans had a predilection for black to decorate walls, resulting in a great need for soot (Figure 1). In what has become a standard work of antiquity, “De Architectura,“ Roman master builder Vitruvius describes in painstaking detail a technical method in which resin is fi red in a brick-lined furnace and Carbon Black is precipitated in large quantities in a special chamber
The preferred feedstock for most Carbon Black production processes, especially the Furnace Black process, is heavy oil with a high content of aromatic hydrocarbons. The aromatic form of carbon gives the greatest carbon-to-hydrogen ratio, thus maximizing the available carbon, and is the most effi cient in terms of Carbon Black yields. Theoretically, the greater the aromaticity the more effi cient the process is. Unfortunately, as the number of combined rings increases the substances move from viscous liquids to solid pitches.
Therefore, in reality the most suitable oils are those in which the majority of the carbon is in the form of substances comprising three- or four-membered rings. Distillates from coal tar (carbo-chemical oils) or residual oils that are created by catalytic cracking of mineral oil fractions and olefi nes manufactured by the thermal cracking of naphta or gasoil (petrochemical oil) also qualify as a source of raw material.
The yield of Carbon Black depends on the aromaticity of the feedstock. It was commonly measured by BMCI (Bureau of Mines Correlation Index) value. However, BMCI is only applicable to feedstocks derived from petroleum. In the case of carbochemicaloils the BMCI may not refl ect the true aromaticity of the product. For this reason the carbon-to-hydrogen ratio is favored for carbochemical products. However, as this measurement is also superior to BMCI, even for petrochemical products, the carbon-to-hydrogen ratio and the carbon content are becoming the preferred criteria for all Carbon Black feedstocks. Additional quality requirements involve impurities from foreign matter. Alkaline metals, for instance, are important because they have a direct eff ect on a specifi c Carbon Black property. The sulfur content of the oil can also play a signifi cant role in production operations since in many countries production sites have to meet strict environmental standards. Sulfur emissions from combustion processes are restricted by law. Furthermore, Carbon Blacks with high sulfur contents might be prohibitive for certain applications. As we look at the various production methods, we will also address the diff erent raw materials that can be used to produce Carbon Black.
2.2.1 Furnace Black Process The most recently developed process, the Furnace Black method (Figure 8) has become the most common in large scale Carbon Black manufacturing. The Furnace Black method is continuous and uses liquid and gaseous hydrocarbons as feedstock and as heat source respectively. When natural gas is available, the liquid feedstock is sprayed into a heat source that is generated by the combustion of the natural gas and pre-heated air. Because it occurs at a very high temperature, the reaction is confi ned to a refractory-lined furnace, hence the name (Figure 10). After the Carbon Black is formed, the process mixture is quenched by injecting water. This also prevents any unwanted secondary reactions. The Carbon Black loaded gas then passes through a heat exchanger for further cooling, while simultaneously heating up the required process air. A bag fi lter system separates the Carbon Black particles from the gas stream. The gases produced by the reaction are combustible and, in most cases, are fed into an afterburning stage where the heat is used to dry the Carbon Black, or are burnt in a boiler to generate steam. The Carbon Black collected by the fi lter has a very low bulk density and, depending on the application, is usually pelletized or further densifi ed to facilitate onward handling. The wet-pelletizing process uses water and a binding agent in a specially designed wet pellet or “pin” mixer, which transforms the Carbon Black into spherical pellets. The Carbon Black pellets are then dried in rotary dryers. The binding agent ensures that the product is resistant to attrition and is easy to process and transport The incorporation of these pellets in a polymer matrix requires substantial shear forces, mostly applied by internal mixers in the rubber industry. Specialty Carbon Blacks that are produced by the Furnace Black process are either loosely densifi ed and packaged as powder Carbon Blacks or are transformed to easily dispersible pellets by application of the drypelletizing process (Figure 11). Oil-pelletized Carbon Blacks, used primarily in the pigment industry, are an additional variant that utilizes mineral oils in the pelletization process. Because of the light oil coating, these Carbon Blacks are characterized by even easier dispersion and virtually dust-free handling. The Furnace Black method off ers environmental and work safety benefi ts. The fully closed installation keeps the emission of process gases and dust to a minimum. Besides its environmental, economic and technical advantages it also allows greater fl exibility because it is capable of manufacturing more diff erent grades of Carbon Black than any other process currently being used. All raw materials are precisely specifi ed in terms of quality, type and quantity. This makes it possible to produce a broad range of Carbon Blacks, which are suitable for use in various applications without fundamentally changing the process for each product variant. For instance, particle size or specifi c surface area can easily be defi ned at the outset by setting the appropriate process parameters. The Furnace Black process also permits the manufacturer to control particle aggregation, the so-called Carbon Black structure, by adding small quantities of an alkaline metal salt. The Furnace Black method creates Carbon Black with primary particle sizes ranging from 10 to 80 nm. The primary particle size is mentioned to indicate the application properties of a given product. Free primary particles do not exist as they are strongly fused together and form so-called aggregates. Examples of Furnace Blacks with diff erent particle sizes and structures are illustrated by the electron microscopic images that are presented on the next page (Figure 12). However, it has not yet been possible to replicate the unique properties of Gas and Lamp Blacks with the Furnace Black method.
2.2.2 Degussa Gas Black Process The Gas Black method developed by Degussa in the mid-1930s is closely related to the Channel Black process developed in the US based on natural gas as the feedstock. As this resource was much scarcer in Europe, the Degussa Gas Black method was developed to use coal tar distillates as raw material instead. In contrast to the Channel Black process, which poses a substantial burden on the environment, gas black plants are at the cutting edge of environmental technology. The facilities are continuously vacuum-cleaned and the Carbon Black is collected in sealed fi lter systems that exceed offi cial emission standards by a signifi cant margin. The Gas Black process uses oil instead of natural gas as the feedstock. The oil is heated in a vaporizer and the resultant vapors are carried by a hydrogen-rich gas into a gas tube that is fi tted with a multiplicity of burners. The individual fl ames impinge on the surface of a water-cooled drum (Figure 14). A portion of the Carbon Black that is generated is deposited on the roller while the rest enters the fi lter system. In the next stage the two Carbon Black streams are combined. Onward processing is then similar to the Furnace Black process. While it is possible to control the raw material fed by the carrier gas stream, the air has free access. However, despite this restriction, the Gas Black method allows the production of Carbon Black with primary particle sizes ranging from 10 to 30 nm. The tradeoff is less fl exibility in defi ning the structure. However, this is not necessarily a disadvantage as Gas Blacks are inherently characterized by a loose structure and exceptional dispersibility
While in the past these types of Carbon Black were used predominantly in tire tread formulations, they are now used almost exclusively in pigment applications where the fi ne-particle Gas Blacks are of particular importance (Figure 15). As a result of contact with oxygen at high temperatures, acidic oxides form on the surface of the Carbon Black particles. In contrast to Furnace Blacks, Gas Blacks undergo an acidic reaction when suspended in water. Oxidative post-treatment using nitrogen dioxide, ozone or other oxidants also make it possible to further in - crease the acidic surface groups signifi cantly. These treated Carbon Blacks are used mostly in the Specialty Carbon Black sector, e.g. in the coating and ink industries. The majority of Gas Blacks are re-treated oxidatively 2.2.3 Lamp Black Process The Lamp Black process is the oldest commercial Carbon Black production process. However, today’s Lamp Black production units have very little in common with the ancient Carbon Black ovens. Smoking chimneys and settlement chambers have long since given way to highly sophisticated fi ltering systems. The Lamp Black apparatus consists of a cast-iron pan that holds the liquid feedstock, which is surmounted by a fi re-proof fl ue hood that is lined with refractory bricks. The air gap between the pan and the hood, as well as the vacuum present in the system, help regulate the air supply and thus enable the manufacturer to fi ne tune the Carbon Black’s ultimate properties. Although the radiated heat from the hood causes the raw material to vaporize and partially combust, most of it is converted to Carbon Black
In order to separate the solids, process gases containing Carbon Black are passed through a fi lter after the cooling stage. Onward processing is similar to that of the Furnace Black method described in section 2.2.1. Although diff erent types of Lamp Blacks were produced in the past, the method was eventually standardized to yield only one type of Specialty Carbon Black and one type of Rubber Carbon Black. These Carbon Blacks are characterized by a broad primary particle size distribution ranging from approximately 60 to over 200 nm and are widely used in special applications.
2.2.4 Channel Black Process (historical) Developed in the United States in the middle of the last century, this Carbon Black production process is based on the incomplete combustion of natural gas. Similar to the Degussa Gas Black process, natural gas fl ames from a vast number of small burners impinge on water cooled channels (Figure 18). Since the 1950s, however, the Channel Black method continuously lost ground in the rubber industry. Following the oil crisis in the 1970s the process was discontinued in the US
The reasons were the limited yield of the raw material (3 – 6 %) and the environmental hazard posed by the emission of very fi ne Carbon Black particles. The thick black smoke billowing from Channel Black plants, called “hot houses,” could be spotted miles away
2.3.1 Thermal Black Process This method of producing Carbon Black is a noncontinuous or cyclic process, with natural gas as the most commonly used feedstock, although higher grade hydrocarbon oils are also used. A Thermal Black plant delivers maximum effi ciency when operated in a tandem mode. It consists of two reactors operating alternately in cycles lasting fi ve to eight minutes. One of which is heated with a natural gas or oil/air mixture while the other is fed with pure feedstock which undergoes thermal decomposition (Figure 20). One could also include the Thermal Black method in the group of thermal-oxidative processes, with the distinction that the energy generation and the decomposition reaction are not simultaneous. However, the fact that the actual Carbon Black formation occurs in the absence of oxygen and at decreasing temperature, results in Carbon Black properties that are markedly diff erent from those achieved by thermal-oxidative processes
Thermal Blacks form relatively slowly, resulting in coarse primary particle sizes ranging from 300 to 500 nm (Figure 21), referred to as medium thermal. However, formerly when using only natural gas as feedstock it was possible to dilute it with inert gases which would produce a Thermal Black composed of primary particles in the range from 120 to 200 nm. This was referred to as fi ne thermal, the latter has virtually disappeared from the market.
2.3.2 Acetylene Black Process At higher temperatures, exothermic decomposition of acetylene yields carbon and hydrogen, forming the basis of the Acetylene Black process. Hydrocarbons are usually added to acetylene in order to prevent reactor temperatures from rising due to the exothermic reaction. Once the reaction mixture has cooled down, the Carbon Black is separated from the hydrogen. Figure 22: Electron microscope view of Acetylene Black particles 2 Manufacturing Process The way Acetylene Blacks are created markedly distinguishes them from thermal-oxidative Carbon Blacks. Although the median primary particle size of Acetylene Black is in the same range as that of some Furnace Blacks (30 to 40 nm), the structure diverges noticeably from the spherical form
Carbon Blacks can also be delivered to the customer in the form of dispersions, which are used to address special dispersibility issues at the customer’s site and also keep pollution levels as low as possible during onward processing. Here a Carbon Black is dispersed in a variety of liquid and solid media in a wide range Table 3: Carbon Black compounds 2.4 Carbon Black Dispersions, Compounds, Plastic and Rubber Masterbatches Carbon Black Compounds Properties Aqueous Dispersions Liquid to paste-like products Pre-Dispersions Powdery products containing water, solvents, wetting agents or softeners Pastes Paste-like products containing resins, softeners, wetting agents, etc. Chips Solids, e. g. Carbon Black/nitrocellulose compounds Plastic Masterbatches Granulated concentrates with up to 50 % Carbon Black content Rubber Masterbatches Carbon black-filled rubber, also in powder form Oil Pellets Oil-containing granules for printing inks of concentrations. The type of Carbon Black and base media are usually specifi ed by the customer leading to a variety of products referred to as Carbon Black preparations. These compounds are classifi ed based on their external appearance
The obvious property of Carbon Black is the deep black color, which is included in the designation in many languages. Carbon Black is classified as a solid and is initially formed as an aerosol or free-floating particles. This is why just-formed Carbon Black has a flaky appearance and is referred to as fluffy Carbon Black at this stage
As shown by chemical analysis, non-treated Carbon Black consists of almost pure carbon. Nevertheless, using the periodic table designator “C” to describe the product would be misleading and therefore not particularly helpful. To characterize Carbon Black, several physical and chemical properties have to be taken into account. Further insights are only possible after incorporating the various types of Carbon Black into the mediums chosen for its possible applications.
The composition described below refers to all Carbon Black grades, regardless of the production method used.
Process-related variations have already been addressed in the description of the various methods in use today for obtaining Carbon Black.
Without the use of photographic image analysis the primary particles of Carbon Black cannot be seen with the naked eye. It takes the tremendous magnifying power of a scanning electron microscope (SEM) to show that Carbon Black consists of chain-like clusters composed of spherical particles, the so-called primary particles. The product is not supplied in the form of isolated primary particles, but as larger, tightly bonded aggregates which form the primary building blocks. The primary particles vary in size and shape to impart specifi c application properties. The primary particle size is mentioned to indicate the application properties of a given product. The aggregates typically form microscale agglomerates during production, present in the supplied powders or pellets. Figure 24 depicts an SEM view of a single particle. The formation of spherical, branched aggregates, where the primary particle can have diameters between 10 and 500 nm, is typical of products that develop from the gaseous phase.
As we cannot see and measure primary particles without involving expensive equipment and time consuming methods this form of Carbon Black has led to the defi nition of two properties 3.1 General Physical and Chemical Properties Element Content (% of wt.) Carbon 96 – 99.5 Hydrogen 0.2 – 1.3 Oxygen 0.2 – 0.5 Nitrogen 0 – 0.7 Sulfur 0.1 – 1.0 Residual Ash < 1 Table 4: Typical elemental Carbon Black composition Figure 24: Scanning electron microscope view of a Carbon Black aggregate consisting of fused primary particles (magnification: x 120,000) that are of primary signifi cance when it comes to characterizing Carbon Blacks and defi ning their suitability for specifi c applications: • The specifi c surface area (m2 /g) of Carbon Black is a function of primary particle size. Looking at geometric proportions, we can determine that smaller Carbon Black primary particles have a higher specifi c surface area. • The structure designates the three-dimensional arrangement of primary particles in the aggregate. Extensive interlinking or branching characterizes a “high structure”, whereas less pronounced inter- linking or branching indicates a “low structure”.
Electron microscopy combined with X-ray structural micro-analysis, shows that these primary particles consist of concentrically arranged, graphite-like crystallites. By partially fusing together, the graphite layers are often twisted into each other, exhibiting a disordered state. A single primary particle can contain up to 1,500 of such crystallites.
Carbon Black can thus be considered as a highly disordered form of graphitic carbon.
By heating the substance to 3,000°C under inert conditions it develops into an ordered graphitic formation.
Turning back to chemical analysis, we see that, besides carbon the elementary analysis of normal Carbon Black also yields minute quantities of oxygen, hydrogen, nitrogen and sulfur (Table 4). Most of these elements are concentrated on the surface of the Carbon Black. The removal of traces of organic elements is possible with the use of special solvents. The Carbon Black extraction based on toluene mostly results in values less than 0.1 %. Partially, the element of hydrogen is directly fused to the carbon element. However, together with oxygen, another portion forms surface-bound functional groups that can be identifi ed by analysis, both qualitatively and quantitatively. Carbonyl, carboxyl, pyrone, phenol, quinone, lactol and ether groups have been identifi ed as the oxygen-containing groups that may be bound to the surface of the Carbon Black particle. Heating the substance up to 950°C, in the absence of oxygen, results in separation. This explains their designation as “volatile matter”. Oxygen containing functional groups on the Carbon Black surface can also be created through specific oxidative post-treatment. Oxygen content levels of 15 % and higher are possible.
These Carbon Black types are especially suitable for treatment with polar binders.
Sulfur is present in a variety of forms: in its elementary form, as a bound molecule and in an oxidized state. High sulfur contents import a certain acidity to the Carbon Black.
Table 5: Typical concentrations of trace metals Nitrogen, when present, is usually contained in the graphite grid.
Sulfur and nitrogen contents are contingent upon feedstock type and quality.
Carbon Black also contains traces of metals. The amounts and types depend on the feedstock used.
Table 5 provides an overview of the metals and their relative content based on OEC`s Rubber and Specialty Carbon Blacks.
Metals Present in Carbon Black Element Content in ppm Antimony < 10 Arsenic < 10 Barium < 10 Cadmium < 1 Chrome < 5 Cobalt < 5 Copper < 5 Lead < 10 Nickel < 10 Mercury < 1 Selenium < 10 Zinc < 10 Among the physical properties of Carbon Black, the following two are important: Density: According to literature and depending on the method used, it may vary from 1.7 to 1.9 g/cm3 . Electrical Conductivity: This aspect is usually not measured in the Carbon Black itself but in the compound containing the Carbon Black, i.e., a polymer or binding agent. Conductivity of a fi lled polymer in creases with the specifi c surface area and the structure of the incorporated Carbon Black. It is also dependent on the Carbon Black concentration and dispersion as well as on the type of polymer or binding agent used
Carbon Blacks are chemically and physically defi ned products obtained under controlled conditions.
Insofar as they are not treated oxidatively, they consist of more than 96 % pure carbon particles and minute quantities of oxygen, hydrogen, nitrogen and sulfur.
The negligible amount of organic substances on the surface of the Carbon Black particle (mostly less than 0.1 %) can be extracted using toluene.
Metal concentrations are likewise negligible. Primary Carbon Black particles, ranging from 10 to approx. 500 nm, fuse into chain like aggregates.
This defines the structure of individual Carbon Blacks. Carbon Blacks that are treated oxidatively differ from those that are not, in the sense that they may contain up to, and sometimes exceeding, 15 % oxygen.
On the other hand, soot (chimney soot and diesel exhaust soot) is a by-product of the uncontrolled combustion of hydrocarbons.
Obtaining precise data on the composition of soot is virtually impossible because the conditions under which it is created are fluctuating, precluding any consistency in terms of quality and properties. Soot can be diff erentiated from Carbon Black based on inorganic and organic impurity contents. Chimney soot, for instance, may have a carbon content of less than 50 %, an extract content of more than 15 % and an ash content of more than 20 %.
For a long time, characterizing Carbon Blacks was a question of determining diff erent shades of black with the human eye.
Precise data on reinforcing eff ects was available only to a limited degree. What exactly the characteristics of a particular Carbon Black were and what it could be used for were questions that could not easily be answered.
In many cases, the development of new Carbon Black grades happened before the characterization of their properties, very much a “hit-and-miss”-situation.
Following the introduction of the Furnace Black method, initially there were only a few basic grades listed.
In the mid-1960s it was discovered that the addition of alkaline metal salts during the production process could be used to infl uence the Carbon Black structure.
This was the first major advancement which led to a broader typology of Furnace Blacks.
For the application to tire treads, high-structure Carbon Blacks were introduced in the rubber industry in the 1960s to improve abrasion resistance.
To determine their structure a quick test method had to be developed.
Test Methods, Chemical and Physical Data 1950 Furnace Black History 1960 1970 2000 2nd stage 3rd stage 4th stage 1st stage Iodine number specific surface area Furnace Black Performance DBP absorption- “structure” “New technology Blacks” “ECORAX®Blacks” Figure 26a: Furnace Black history Following a series of comparative tests, DBP (dibutyl phthalate) absorption ultimately became the preferred tool for determining Carbon Black structure.
Difficulties arose in the early 1970s when advances in technology led to a new category of reinforcing Carbon Blacks in Furnace Black production.
Compared to the standard grades available at the time these so-called new technology or improved blacks showed improved abrasion resistance without any apparent change in the iodine number.
The differences between these new technology blacks and standard Carbon Blacks were not easily detectable with the methods available at the time.
Therefore, physical and chemical characterization methods had to be developed in order to establish production parameters, which ensured that the correct Carbon Black characteristics were achieved.
All Carbon Black characterization methods existing today are used to defi ne collective properties, which are based on the sum of properties determined for the individual particles.
This means that we are dealing with a maximum variation of particle properties in a range with statistical maximum.
It is up to the skilled technician to adjust the peak of the distribution curve at a specifi c value and defi ne the width of the curve.
As long as geometric data is what is being processed and analyzed, the electron microscope is a helpful tool in determining the distribution curve.
Other parameters, like conductivity, cannot be determined for the individual particles.
As already pointed out, the average primary particle size and the average aggregate size form the primary characteristic data.
However, the particle size distribution and the aggregate size distribution are at least as important.
As an alternative to lengthy electron microscope analysis a number of methods have been developed to enable a quicker characterization and allow conclusions to be drawn for subsequent Carbon Black applications.
While various surface characterization methods have gradually replaced those for particle size determination, the aggregate size distribution is now determined via specialized methods such as sedimentation, ultra-centrifugation and light refraction.
De facto there are various characterization methods in use today, which indicate that a general characterization of Carbon Black is impossible.
It is necessary to specifi cally adapt identifying methodologies to the various areas of application.
Most Carbon Black properties are determined based on industry standards, which have been developed by the German Institute of Standardization (Deutsches Institut für Normung e.V. - DIN), the International Organization for Standardization (ISO) and the ASTM International (formerly known as the American Society for Testing and Materials).
These standards are not only used as a measure by which Carbon Blacks are characterized, but also as a quality assurance tool for the production process (Table 6).
In addition to these Carbon Black reference profiles, a number of more practical testing methods are used today, especially for testing Rubber Carbon Blacks in relation to their end use segments.
These tests may be conducted in standard rubber formulations and are used to establish characteristic and consistent profile data on the impact of the Carbon Black in the rubber compound.
Obviously, these methods off er only a glimpse of the comprehensive systems available for testing and evaluating Rubber Carbon Blacks.
Special testing methods also exist for Carbon Black applications in the plastics, coatings and printing inks industries.
Determination of Surface Area The specific surface area of a Carbon Black is mainly derived from the particle geometry using adsorption methods.
Iodine adsorption, measured in mg/g, is the most common technique.
Iodine adsorption is a quick test method for dry Carbon Black.
Surface groups and adsorbed substances infl uence this specifi cation method.
For the iodine number to refl ect the real surface area, it is important that neither increased amounts of volatile matter nor higher toluene extracts disturb the measurement.
This in turn limits this method to Furnace Blacks with low toluene extractions and Lamp Blacks.
Furnace Blacks with high contents of solvent extractable material, Gas Blacks and treated Carbon Blacks cannot be analyzed using this method.
That is mainly why this parameter is usually not stated when dealing with Specialty Carbon Blacks.
CTAB adsorption, introduced primarily for the characterization of improved Carbon Blacks, comes closest to an accurate determination of the geometric surface, i.e., not including the pores.
That is because cetyl trimethyl ammonium bromide (CTAB) has a greater space requirement than nitrogen.
TDetermination of Structure The structure of Carbon Black aggregates can only be determined indirectly.
The most commonly accepted method is based on oil absorption.
In this test, paraffin oil (formerly dibutyl phthalate, DBP) is added by means of a constantrate burette to a sample of the Carbon Black in the mixer chamber of an absorptometer.
As the sample absorbs the oil the mixture changes from a free-fl owing powder to a semi-plastic continuous mass.
This leads to a sharp increase in viscosity, which is transmitted to the torque-sensing system of the absorptometer.
The endpoint of the test is given by a pre-defi ned torque level.
The result is expressed as the oil absorption number (OAN), in ml/100 g.
A high OAN number corresponds to a high structure, i.e. a high degree of branching and clustering of the aggregates.
Mechanical stress can be applied to destroy agglomerates.
This eff ect is used for determining the structure based on the oil absorption of a compressed sample (COAN).
Following four repeated applications of pressure at predefi ned levels, the oil absorption of the mechanically stressed Carbon Black is measured by the conventional oil absorption method.
As a general rule, COAN values are lower than OAN values.
Another parameter, Carbon Black oil absorption according to ISO 787/5, is measured using the socalled fl owpoint method.
The flowpoint registers the maximum quantity of oil (usually linseed oil) that can be added to Carbon Black and still allow for a non-deliquescent cone to form from the mixture.
Although the method is not the most accurate, oil absorption is an important indicator in coating applications because a high oil absorption level points to a high binding agent requirement.
The Carbon Black structure and particle size, but most of all density and surface chemistry, all have an effect on oil absorption.
Colorimetric Characterization Jetness refers to the intensity of blackness that is achievable.
The most accurate instrument for measuring what are often very minute diff erences is the trained eye which can diff erentiate between up to 100 different shades of black.
A method for measuring residual reflection
Chemical and Physical Measurements
The volatile matter content gives an indication of the Carbon Black’s oxygen concentration and is determined by heating the Carbon Black up to 950°C.
This parameter is especially important for testing Carbon Blacks that have been post-treated.
The ash content points to the level of inorganic impurities coming primarily from the feedstock - iron, calcium and silicon are among the most common.
Gas and Acetylene Blacks are characterized by a very low ash content due to their production process.
The sieve residue provides information on particulate impurities which may contain metal or ceramic particles originating from the production unit or coke particles formed during the production process.
As a result of their high adsorbency, moisture is an issue when storing Carbon Black.
High-structure Carbon Blacks, and in particular oxidatively post-treated Carbon Blacks, are more likely to have elevated moisture content levels.
The pH of a Carbon Black is measured in an aqueous suspension.
Untreated Carbon Blacks have a diff erent pH depending on the process used: Gas Blacks are always acidic because of their oxidized surface.
Furnace Blacks, on the other hand, are generally alkaline because small quantities of basic oxides are present on the surface.
Lamp Blacks, Thermal Blacks and in some cases also Acetylene Blacks are characterized by alkaline to neutral reactions.
Physical Appearance and Handling Properties
To determine the space requirement of powder and pelletized Carbon Blacks either the bulk or pour density, or the compacted or tapped density, is measured.
The structure is reflected by pour density.
High-structure Carbon Blacks show a lower bulk density than low-structure Carbon Blacks.
In the case of pelletized Carbon Blacks, the pellet hardness is a signifi cant quality parameter as it gives an indication of pellet fragility and hence of the resistance to attrition rate.
This resistance is characterized by pellets being destroyed and ultimately ground to dust by friction.
While softer pellets make for better dispersion, their inherent propensity towards fi nesse may create handling issues.
The pellet size distribution is a parameter that aff ects the flow characteristics of pelletized Carbon Blacks.
A uniform pellet size means a lower bulk density, hence ensuring optimum flow behavior.
What is carbon black?
A vital component in making many of the products we use every day stronger, deeper in color and longer lasting, carbon black in its pure form is a fine black powder, essentially composed of elemental carbon. It is produced by partial burning and pyrolysis of low-value oil residues at high temperatures under controlled process conditions.
Carbon black is mainly used to strengthen rubber in tires, but can also act as a pigment, UV stabilizer, and conductive or insulating agent in a variety of rubber, plastic, ink and coating applications. Apart from tires, other everyday uses of carbon black include hoses, conveyor belts, plastics, printing inks and automotive coatings.
The fundamental properties of carbon black determine application performance.
• Particle Size
• Surface Chemistry or Surface Activity
• Physical Form
Measured by electron microscopy, this is the fundamental property that has a significant effect on rubber properties, as well as color properties for specialty carbon blacks.
For specialty carbon blacks, smaller particle diameter gives rise to higher surface area and tinting strength.
High surface area is usually associated with greater jetness, higher conductivity, improved weatherability, and higher viscosity, but requires increased dispersion energy.
For rubber, finer particles lead to increased reinforcement, increased abrasion resistance, and improved tensile strength.
To disperse finer particles size, however, requires increased mixing time and energy.
Typical particle sizes range from around 8 nanometers to 100 nanometers for furnace blacks.
Surface area is utilized in the industry as an indicator of the fineness level of the carbon black and, therefore, of the particle size.
This is a measure of the three-dimensional fusion of carbon black particles to form aggregates, which may contain a large number of particles.
The shape and degree of branching of the aggregates is referred to as structure.
Highly structured carbon blacks provide higher viscosity, greater electrical conductivity and easier dispersion for specialty carbon blacks.
Measures of aggregate structure may be obtained from shape distributions from EM analysis, oil absorption (OAN) or void volume analysis.
The structure level of a carbon black ultimately determines its effects on several important in-rubber properties.
Increasing carbon black structure increases modulus, hardness, electrical conductivity, and improves dispersibility of carbon black, but increases compound viscosity.
This is a fundamental property of carbon black that can be controlled during the production process.
It can affect the measurement of surface area providing a total surface area (NSA) larger than the external value (STSA).
Conductive specialty carbon blacks tend to have a high degree of porosity, while an increase in porosity also allows a rubber compounder to increase carbon black loading while maintaining compound specific gravity.
This leads to an increase in compound modulus and electrical conductivity for a fixed loading.
SURFACE CHEMISTRY OR SURFACE ACTIVITY
This is a function of the manufacturing process and the heat history of a carbon black and generally refers to the oxygen-containing groups present on a carbon black’s surface.
For specialty carbon blacks, oxidized surfaces improve pigment wetting, dispersion, rheology, and overall performance in selected systems.
In other cases, oxidation increases electrical resistivity and makes carbon blacks more hydrophilic.
The extent of surface oxidation is measured by determining the quantity of the “volatile” component on the carbon black.
High volatile levels are associated with low pH.
While difficult to measure directly for rubber, surface chemistry manifests itself through its effects on such in-rubber properties as abrasion resistance, tensile strength, hysteresis, and modulus.
The effect of surface activity on cure characteristics will depend strongly on the cure system in use.
This is important in matching a carbon black to the equipment by which it is to be dispersed.
The physical form (beads or powder) can affect the handling and mixing characteristics.
The ultimate degree of dispersion is also a function of the mixing procedures and equipment used.
Powdered carbon blacks are recommended in low-shear dispersers and on three-roll mills.
Beaded carbon blacks are recommended for shot mills, ball mills, and other high energy equipment.
Beading provides lower dusting, bulk handling capabilities, and higher bulk densities, while powdered carbon blacks offer improved dispersibility
Carbon black as a thermoset composite colorant.
The general idea of coloring thermoset composites black or perhaps a dark gray seems simple and straightforward.
One could simply add a dispersion of carbon black or a carbon black powder to the composite formulation.
While in theory this sounds very uncomplicated, in practice it can be technically challenging.
Carbon black pigments are used not only as a colorant, they are very efficient at absorbing light across the visible spectrum and the ultraviolet spectrum.
Carbon black is also popular in a myriad of other applications such as automobile coatings, tires, laser and ink jet printers, and the coloration of many types of plastics composite applications
1. Rubber reinforcement
Carbon black is a rubber-reinforcing additive used in a multitude of rubber products.
In particular, in case of vehicles, large amounts of carbon black are used for tires.
In addition, carbon black is used with rubber to dampen earthquake vibration, in the soles of shoes and in many other products.
2. Colors and pigments for plastics
Compared with other colorants, carbon black has a high coloring power.
Therefore. it is used as ink for printing newspapers, as ink-jet toner, and other such uses.
It is also suitable as a pigment for heat-molded plastics, car fenders, coating for electric wires and other products.
3. Electric equipment and conductive components
Since carbon black has excellent conductive properties, it is used as a component for magnetic tapes and semiconductors.
There is a reason why tires are black. It's because fine particles of carbon called "carbon black" are mixed in with the rubber.
In fact, carbon black can make up about 30% of the weight of a tire.
Its job is to make the tires stronger and more long-lasting.
Carbon black can also be found in the black ink used in inkjet printers and in the rubber parts of many industrial products.
Carbon black’s nano-scale particles mean that it has a wide range of applications.
An essential part of many newly developed products, it plays a role in many facets of our lives
A very important filler in the rubber industry and next to titanium dioxide, the most important pigment, printing inks, toners, single-ply roofing, inks, paints and plastics.
The most common use [70%] of carbon black is as a pigment and reinforcing phase in automobile tires.
Carbon black also helps conduct heat away from the tread and belt area of the tire, reducing thermal damage and increasing tire life.
Carbon black particles are also employed in some radar absorbent materials and in photocopier and laser printer toner.
A black, amorphous, carbon pigment produced by the thermal decomposition of natural hydrocarbons. There are three different types (furnace, channel, and lamp black).
Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Carbon black is a form of amorphous carbon that has a high surface area to volume ratio, although its surface area to volume ratio is low compared to activated carbon. It is dissimilar to soot because of its much higher surface area to volume ratio and significantly less (negligible and non-bioavailable) PAH content. Carbon black is used as a pigment and reinforcement in rubber and plastic products.
Chemical Name: Amorphous carbon
Carbon black, Carbon Lampblack, Acetylene black, Animal bone charcoal, Lampblack, lamp black, Fullerene tubes, Carbon soot, CAS# 7782-42-5
Carbon black (CB) is a common denomination for particles with a carbonaceous core, produced by incomplete combustion of heavy petroleum products and used as a black pigment
Carbon black (CB) is derived via thermal decomposition of heavy petroleum products.
CB is generally used as a reinforcing and support material for metal catalyst due to its higher electrical conductivity, high surface area, and stability
Carbon black pigments are manufactured today mainly by modern chemical processes in industrial scale production.
They are the most important represen-tatives of black pigments.
Carbon black pigments have a number of advantagescompared with other inorganic black pigments and with black organic colorants.
Hiding power, color stability, solvent resistance, acid and alkali resistance as wellas thermal stability are excellent good properties that are not achieved from otherblacks.
Carbon black pigments are applied in most of the pigment relevant systems,such as printing inks, paints and coatings, plastics, and cosmetics.
They are produced by several industrial processes.
Furnace blacks, channel blacks and gasblacks have the highest importance among the various carbon blacks.
Particle size,particle size distribution, surface quality and structure determine the coloristic andapplication technical properties of the individual pigments.
Oxidative aftertreatment is used in many cases to modify the surface of the pigments concerning thestability and the compatibility with the application system.
Particle management,aftertreatment and the provision of pigment preparations are suitable ways for the improvement of the pigments and the optimization of the dosage form.
Keywords:carbon black pigments, channel black process, furnace black process,gas black process, oxidative aftertreatment
Fundamentals and properties
Inorganic black pigments include carbon black, iron oxide black and spinel blacks.
Carbon black pigments are by far most important among the blacks.
The term“carbon black”stands for a number of well-defined industrially manufactured products, which are manufactured under exactly controlled conditions.
Carbon black consists of highly dispersed carbon particles with almost spherical shape.
These particles are produced by incomplete combustion or thermal decomposition of gaseous or liquid hydrocarbons.
Carbon blacks do not consistof pure carbon.
They still contain considerable amounts of chemically bound hydro-gen, oxygen, nitrogen, and sulfur depending on the manufacturing conditions and the quality of the raw materials.
Carbon black is not only applied as a pigment, butalso as active filler material in rubber, particularly in car tires.
Natural gas tank method of making carbon black: take natural gas as raw material and use iron pipe to send it into the combustion chamber.
The form of the combustion chamber can be either long and short and is made of iron plate. It contains a number of olefin burner inside it.
Natural gas is sprayed with appropriate force from the burner nozzle and burned in the case of insufficient air, that is, to generate a bright and black smoke flame.
The flame then goes directly into the channel iron with the distance between the burner and the slot surface being 65~80 mm.
At this time, the temperature of olefin burning is reduced from about 1000 to 1400 ° C to about 500 ° C, and the carbon black is accumulated.
The groove can move back and forth horizontally, with a moving speed of 3 to 4 mm/s.
In order to maintain normal production, the required amount of air is about 2.5 to 3 times the theoretical calculation. The resulting carbon black was scraped into a funnel with a fixed doctor blade and sent to a central packing chamber for disposal.
Then the carbon black is softened, filtered to remove the hard particles and scale and further sent into the mill grinding to enable more uniform thickness.
However, the body is still very light and loose, thus should be shaken to a become a bit solid.
Then add a small amount of water to the carbon black to make it into paste-like shape and have a small needle rotated inside it to forming micro-pellets, followed by drying to obtain the finished product. In the case of using pigment for carbon black, in order to facilitate the dispersion, the granulation is unnecessary. The process is as follows:
Raw gas, air → combustion cracking → collection → granulation → packaging → finished product.
Carbon black is one of the oldest industrial products. In ancient times, china has already applied incomplete combustion of vegetable oil for making pigment carbon black. In 1872, the United States first used natural gas as raw material to produce carbon black using tank method and mainly used it as a coloring agent. It was not until 1912 when Mott found the reinforcement effect carbon black on the rubber before the carbon black industry had gotten rapid development. Then it had successively developed of a variety of process methods. At present, oil furnace method is the most efficient and most economical method with the oil furnace black production amount accounting for 70-90% of the total carbon black production. There are mainly furnace, slot method, thermal cracking, three methods.
It is obtained by the carbonization of the plant material such as peat. It can also be derived from the carbonization of cocoa shell and beef bone or from the combustion of vegetable oil.
1. It is edible black pigment. It can be used for pastry with the usage amount of 0.001% to 0.1%.
2. It can be used for food coloring agent. China provides that it can be used for rice, flour products, candy, biscuits and pastries with the maximum usage amount of 5.0g/kg.
3. Rubber industry uses it as a reinforcing filler. 2. Paint Inks applies it as coloring pigments in paint inks. 3. Used for the manufacturing of black paper such as packaging materials for photographic materials and the black paper made of high-conductivity black carbon in the radio equipment. 4. Carbon paper and typewriter; it is used when it is required for darker colors and can remain on the carrier. 5. Plastic coloring, ink, phonograph records, shoe polish, paint cloth, leather coatings, colored cement, electrodes, electronic brushes, batteries and so on.
4. As electric conductive agent of lithium ion battery;
5. Mainly used for rubber, paint, ink and other industries;
6. Used for the reinforcement of car tread and sidewall, hose, groove, industrial rubber products as well as conveyor belt.
7. Used for tire tread, surface tire repair, automotive rubber parts, conveyor belts, conveyor pads, etc., The vulcanized glue of this carbon black shows excellent tensile strength and abrasion resistance
8. It is mainly used for the reinforcement of tire belt, sidewall, solid tires, outer layer of roller, hose surface, industrial rubber products and car tire tread.
9. It is used for the reinforcement of the tire tread of car and truck, surface of conveyor belt and industrial rubber products.
10. For rubber reinforcement, coloring agent, metallurgy, rocket propellant
11. For rubber products to fill and reinforcement.
12. For rubber products, carcass, valves and other filling .
13. For paints and inks, plastics and other industries.
14. Mainly used for raw materials of battery as well as for conductive and anti-static rubber products.
15. In the rubber industry, it is used as the reinforcing agent and filter for the manufacturing of natural rubber and butyl rubber, being able to endow the vulcanized rubber with excellent tensile strength, elongation and tear resistance and so on. It should be mostly used for natural rubber-based large-scale engineering tires and a variety of off-road tires as well as being used for carcass and sidewall. In addition, it can also be used for high-strength conveyor belt, cold rubber products and drilling device. In light industry, it can be used as the filter of the paint, ink, enamel and plastic products.
Solubility: being insoluble in water and organic solvents (OT-42)
Heated to red, burning without flames.
The sample was pre-dried at 120 ° C for 4 h and then measured by an instrument such as a C.H. O analyzer or subject to combustion/gravimetric analysis.
ADI has not yet been specified. It is listed as substance allowed to be in temporary contact with food, (FAO/WHO, 2000). It can not be digested and absorbed, so oral administration should be non-toxic, but given the incorporation of 3, 4-benzopyrene during the carbonization, it is basically not used now.
Use the limit
GB 2760-1996: Confectionery, biscuits, pastries, rice and flour products, 5.0 g/kg.
EEC provides for being used for concentrated fruit juice, jam, jelly, fruit wine.
It appears as black powdery particles with a particle size of 0 to 500 μm.
The relative density is 1.8 to 2.1.
It is insoluble in water and organic solvents.
Hazards & Safety Information
Category Toxic substances
Toxicity classification Low toxicity
Acute Toxicity Oral-Rat LD50:> 15400 mg/kg
Explosives and hazardous characteristics being explosive upon dust and air mixture
Flammability and Hazardous characteristics It is combustible in case of heat and strong oxidant
Storage and transportation characteristics Treasury: low temperature, ventilated and dry
Fire extinguishing agent water, carbon dioxide, dry powder, foam
Occupational Standard TWA 3.5 mg/m3; STEL 7 mg/m3
finely divided black dust or powder
Carbon black (essentially elemental carbon), is a black or brown liquid or solid (powder). Odorless solid. Carbon black oil is flammable and has a petroleum odor.
Carbon black [1333-86-4] is virtually pure elemental carbon (diamond and graphite are other forms of nearly pure carbon) in the form of near-spherical colloidal particles that are produced by incomplete combustion or thermal decomposition of gaseous or liquid hydrocarbons. Its physical appearance is that of a black, finely divided pellet or powder, the latter sometimes small enough to be invisible to the naked eye. Its use in tires, rubber and plastic products, printing inks and coatings is related to the properties of specific surface area, particle size and structure, conductivity and color.
It is in the top 50 industrial chemicals manufactured worldwide, based on annual tonnage.
Current worldwide production is about 15 billion pounds per year (6.81 million metric tons).
Approximately 90% of carbon black is used in rubber applications, 9% as a pigment, and the remaining 1% as an essential ingredient in hundreds of diverse applications.
Modern carbon black products are direct descendants of early “lampblack”, first produced in China over 3500 years ago.
These early lampblacks were not very pure and differed greatly in their chemical composition from current carbon blacks. Since the mid-1970s most carbon black has been produced by the oil furnace process, which is most often referred to as furnace black.
Unlike diamond and graphite, which are crystalline carbons, carbon black is an amorphous carbon composed of fused particles called aggregates. Properties, such as surface area, structure, aggregate diameter and mass differentiate the various carbon black grades.
Uses In the rubber, plastic, printing, and paint industries as a reinforcing agent and a pigment
Uses Tire treads, belt covers, and other abrasion- resistant rubber products; plastics as a reinforc- ing agent, opacifier, electrical conductor, UV- light absorber; colorant for printing inks;carbon paper; typewriter ribbons; paint pigment; nucleat- ing agent in weather modification; expanders in bat- tery plates; solar-energy absorber (see note).
Definition A finely divided form of carbon, practically all of which is made by burning vaporized heavy-oil frac- tions in a furnace with 50% of the air required for complete combustion (partial oxidation). This type is also called furnace black. Carbon black can also be made from methane or natural gas by crack- ing (thermal black) or direct combustion (channel black), but these methods are virtually obsolete. All types are characterized by extremely fine particle size, which accounts for their reinforcing and pig- menting effectiveness.
Definition A finely divided form of carbon produced by the incomplete combustion of such hydrocarbon fuels as natural gas or petroleum oil. It is used as a black pigment in inks and as a filler for rubber in tire manufacture.
Definition carbon black: A fine carbon powdermade by burning hydrocarbons in insufficientair. It is used as a pigmentand afiller (e.g. for rubber).
Acetylene Black DENKA
Acetylene Black DSPL
C.I. Pigment Black 7
Carbon Black amorphous
Carbon black; Acetylene black
butyl reclaimed rubber
Carbon Black BV and V
Carbon Black Chezacarb AC - type A
Carbon Black Chezacarb AC - type A+
Carbon Black Chezacarb AC - type B
Carbon Black-Grade N-326
CI Pigment Black 6
CI Pigment Black 7
Diamond Carbon Blacks
Farbruss, Colour Black
Farbruss; colour black
Flammruss, Colour Black
Flammruss; colour black
LIONITE EC200LCARBON ECPCARBON ECP600JDCARBON ECP200L
MITSUBISHI CARBON BLACK
MPC Channel black
P 805 S
rubber powdersadza techniczna
Saze Chezacarb AC - typ A
Saze Chezacarb AC - typ A+
Saze Chezacarb AC - typ B
Thermax ® Powder
Thermax ® Powder Ultra Pure
Thermax ® Stainless
Thermax ® Stainless Powder
Thermax ® Stainless Powder Ultra Pure
Thermax ® Ultra Pure
tire reclaimed rubber
tread tire reclaim
whole tire reclaim