Carbon Black

What Carbon Black Is and Why It Remains the Primary Reinforcing Filler

Carbon black, also known as technical carbon or soot, is a finely dispersed amorphous carbon produced by thermal-oxidative or thermal decomposition of hydrocarbons in the gas phase. In commercial form it is a black powder or pellets, with bulk density depending on the granulation method. The primary function of carbon black in rubber compounds is reinforcement: adding 30-50 parts by mass of filler per 100 parts of rubber increases the strength, hardness, wear resistance and tear resistance of vulcanizates many times over.

N220, N330 and N550 grades belong to the furnace active carbons and occupy different positions in the ASTM D1765 classification. N220 (ISAF, Intermediate Super Abrasion Furnace) is characterized by high fineness and high reinforcing effect; N330 (HAF, High Abrasion Furnace) is the most versatile grade with a balance of strength and hysteresis loss; N550 (FEF, Fast Extrusion Furnace) has coarser particles and provides good extrudability of compounds. This combination of properties makes the three grades the most demanded in the tire and mechanical rubber goods industry.

For procurement teams, carbon black is interesting as a large-tonnage material with clearly standardized quality parameters and a wide supply geography. Unlike many polymer materials, carbon black does not require special storage temperatures, but it is sensitive to moisture and contamination, which must be taken into account when organizing logistics.

Chemical Identification and Procurement Data

• Chemical name: technical carbon, amorphous carbon, soot.
• Synonyms: carbon black, technical carbon, acetylene black (for specialty types).
• CAS number: 1333-86-4.
• Chemical formula: C.
• HS code: 2803000000 for carbon (carbon black and other forms of carbon).
• Commercial form: black pellets or powder; granulated carbon is preferred for mechanized loading and dust reduction.

N220, N330 and N550 grades correspond to the ASTM D1765 classification, which assigns designations by iodine number (first digit) and structure (second and third digits). In Russian practice, carbon black for rubber is produced under GOST 7885-86, which establishes requirements for a range of grades including P 245, P 234 and others. N-series grades (N220, N330, N550) are widely represented in imports and in products manufactured to ASTM standards. When purchasing, the specification states the ASTM grade designation and, where applicable, a reference to GOST 7885-86 or the manufacturer technical specification.

Physical and Chemical Parameters Relevant to Processing

The quality of carbon black is assessed by a set of parameters that determine its reinforcing effect, processability and behavior in the rubber compound.

• Iodine Adsorption Number: 121 ± 5 g/kg for N220; 82 ± 5 g/kg for N330; 43 ± 4 g/kg for N550. Iodine number correlates with surface area and fineness.
• DBP Absorption Number: 114 ± 5 cm3/100 g for N220; 102 ± 5 cm3/100 g for N330; 121 ± 5 cm3/100 g for N550. Characterizes structure, i.e., the degree of aggregate branching.
• CTAB surface area: 105-117 m2/g for N220; 83-95 m2/g for N330; 37-47 m2/g for N550.
• STSA surface area: 106 ± 5 m2/g for N220; 75 ± 5 m2/g for N330; 39 ± 5 m2/g for N550.
• Mean primary particle size: 20-25 nm for N220; 28-36 nm for N330; 39-55 nm for N550.
• Heating loss (moisture): typically not more than 1.0-2.5 percent depending on grade and packaging.
• Ash content: not more than 0.5-0.7 percent.
• Pellet bulk density: 300-400 kg/m3 for typical granulated grades.
• pH of aqueous suspension: typically 5.5-8.5 depending on production technology and treatment.

For the processor, two parameters are critical: fineness (iodine number, surface area) and structure (DBP absorption). The high fineness of N220 provides maximum reinforcement and wear resistance but increases hysteresis loss and heat build-up. N330 offers a balanced property set and is the most versatile grade. N550 with coarser particles and high structure improves extrudability and reduces compound stiffness, which is important for extruded profiles and sidewalls.

Technical Grades and Supply Forms

N220 (ISAF)

High-fineness grade with an iodine number of 121 g/kg and DBP absorption of 114 cm3/100 g. Provides high strength, wear resistance and tear resistance. Used in tread compounds of passenger and truck tires, high-strength conveyor belts and demanding mechanical rubber goods. Increased heat build-up must be considered when designing thick-walled articles.

N330 (HAF)

Versatile grade with an iodine number of 82 g/kg and DBP absorption of 102 cm3/100 g. Combines high strength with moderate hysteresis. Used in treads, carcass compounds, breaker, inner tire layers, as well as a wide range of mechanical rubber goods: belts, hoses, seals, coverings.

N550 (FEF)

Grade with coarser particles (iodine number 43 g/kg) and high structure (DBP absorption 121 cm3/100 g). Provides good extrudability, low heat build-up and smooth profile surfaces. Used in tire sidewalls, carcass compounds, hoses, cable sheaths, seals and articles requiring processing ease during extrusion.

Carbon black is supplied in granulated form in paper or polypropylene bags of 20-25 kg, in 500-1000 kg big bags, and in bulk in specialized containers or tank cars. The granulated form is preferred for automated loading systems.

Regulatory Framework for Incoming Inspection

• GOST 7885-86 - technical carbon for rubber production. Specifications.
• ASTM D1765 - standard classification system for carbon black.
• ASTM D1510 - determination of iodine number.
• ASTM D2414 - determination of DBP absorption (OAN).
• ASTM D6556 - determination of STSA surface area.
• ASTM D1506 - determination of ash content.
• ASTM D1509 - determination of heating loss.
• ISO 1124 - sampling of carbon black.

For imported batches, the specification is based on ASTM D1765 and ASTM methods. For products manufactured under GOST 7885-86, conformity to the standard is confirmed. The batch specification is confirmed by the manufacturer certificate of quality and the results of incoming laboratory control by the recipient.

Mechanism of Action and Functional Role

The reinforcing effect of carbon black in elastomers is due to physicochemical interaction between the filler surface and rubber macromolecules, as well as the formation of a filler network. High-fineness grades with a large specific surface area provide more contact points with the polymer, leading to increased modulus, strength and wear resistance. However, the same parameters increase hysteresis loss and heat build-up under cyclic deformation.

Structure, characterized by DBP absorption, determines the degree of particle aggregation and affects the viscosity of the unvulcanized compound, shrinkage and extrudability. The high structure of N550 facilitates processing and reduces stiffness, while the moderate structure of N330 and N220 contributes to higher strength and tear resistance. Choosing a grade for a specific formulation is always a compromise between reinforcement, hysteresis and processability.

Applications by Industry

Tire Industry

Dominant consumption direction. N220 is used in tread compounds of passenger and truck tires requiring high wear resistance and tear resistance. N330 is used in treads, carcass compounds, breaker and bead compounds. N550 is demanded in sidewalls, carcass layers and compounds for extruded profiles where surface smoothness and low heat build-up are important.

Mechanical Rubber Goods

N330 and N550 are used in conveyor belts, drive belts, hoses, seals, gaskets and molded articles. N220 is used in articles operating under high loads and requiring maximum wear resistance.

Plastics and Cable Compounds

Carbon black serves as a pigment, UV stabilizer and electrically conductive additive in polyethylene, polypropylene, PVC and other plastics. N550 and similar grades are used in cable sheaths and semiconductive screens.

Paints, Pigments and Specialty Applications

High-fineness grades are used as black pigment in coatings, printing inks and toners. Depending on surface treatment and fineness, carbon black provides various shades of black and degrees of gloss.

Comparison with Alternative Fillers and Pigments

Compared with mineral fillers (chalk, kaolin, talc), carbon black provides significantly higher reinforcement of rubbers but is inferior in its ability to reduce compound cost. Compared with silica fillers, carbon black provides higher electrical conductivity and black color but is inferior in wet skid resistance in so-called green tires.

For pigment applications, carbon black competes with black organic and inorganic pigments. In terms of hiding power and light fastness, it surpasses most organic pigments but is inferior in brightness and shade purity. In electrically conductive compounds, carbon black remains the most economical and processable filler, although it is inferior to carbon nanotubes and graphene in achievable conductivity at low loading levels.

Supplier Selection Criteria and Specification Development

The specification for carbon black must include the ASTM or GOST grade, iodine number, DBP absorption, CTAB or STSA surface area, ash content, heating loss and supply form (pellets or powder). For pigment and specialty grades, dispersibility, pH and sieve residue are additionally specified.

The supplier confirms batch-to-batch consistency, a valid safety data sheet and packaging suitable for mechanized unloading. When choosing between granulated and powdered material, the type of loading equipment and dust requirements at the production site are taken into account.

Typical Handling and Processing Errors

• Ignoring moisture. Increased moisture of carbon black leads to caking, uneven dispersion and porosity in vulcanizates. Incoming control of heating loss is mandatory.
• Insufficient dispersion. Carbon black tends to form agglomerates; incomplete dispersion reduces the reinforcing effect and causes surface defects in articles.
• Mixing grades without reformulation. Replacing N220 with N330 or N550 without adjusting dosage and plasticization changes the property set of the rubber.
• Violation of storage conditions. Bags and big bags should be stored in dry closed warehouses, protected from atmospheric precipitation and contamination.
• Neglecting dust protection. Powdered carbon black generates dust that can accumulate on equipment and create a fire hazard; granulated grades and aspiration systems are recommended.

Quality Control and Laboratory Methods

Incoming inspection of carbon black includes determination of iodine number, DBP absorption, surface area, ash content and heating loss. For pigment grades, dispersibility and sieve residue are additionally controlled. Sampling is performed in accordance with ISO 1124 or ASTM D1799, and the combined sample is analyzed in the plant laboratory. To confirm suitability for a specific formulation, a control run of the rubber compound with evaluation of vulcanization characteristics and physical and mechanical properties is recommended.

Storage and Transportation Conditions

Carbon black is not classified as a hazardous good. Storage is carried out in closed dry warehouses at ambient temperature, without access to atmospheric precipitation and direct sunlight. Bags and big bags are placed on pallets and protected from mechanical damage. The shelf life is typically 24 months from the date of manufacture under proper transport and storage conditions.

Transportation is by rail, road and sea in covered cars, containers or vans. Bulk shipments use specialized containers or tank cars providing protection from moisture.

Finding Analogues and Interchangeability

When replacing carbon black, a grade with similar iodine number and DBP absorption is selected. Direct replacement of N220 with N330 or N550 is possible but requires formulation adjustment and confirmation of vulcanizate properties. Similar grades from different manufacturers may differ in aggregate molecular weight distribution and surface treatment, so replacement must be confirmed by laboratory testing and a control run. For pigment applications, shade and dispersibility are also important and may differ even when the main parameters match.

Supply Routes: Russia, China and Other Regions

Domestic supply of carbon black is provided by petrochemical and carbon black production facilities. Products are supplied to the domestic market and for export; shipment is carried out by rail and road transport.

Chinese producers of carbon black have large capacities and a wide grade range. Supplies are delivered by sea with subsequent transfer to rail or road transport. Other global producers are located in India, the Middle East, Southeast Asia and Europe. Suppliers from these regions are engaged when required, taking into account logistical and regulatory factors.

Logistics and Customs Clearance

Transportation is carried out in bags on pallets, big bags and containers. Customs clearance includes classification under HS code 2803000000, preparation of a safety data sheet and conformity declaration. The portal provides customs broker services and supports all clearance stages.

Risk Factors and Safety Measures

The main risks are associated with moisture, contamination and dust. Maintaining packaging integrity, dry storage conditions and the use of aspiration systems minimize these risks. Carbon black is not a toxic substance, but prolonged inhalation of dust can irritate the respiratory tract, so respiratory protection is recommended when handling powdered grades.

FAQ: Common Questions from Procurement and Process Specialists

How does N220 differ from N330 and N550

N220 has the highest fineness (iodine number 121 g/kg) and provides maximum reinforcement and wear resistance. N330 (82 g/kg) is a versatile grade with a balanced property set. N550 (43 g/kg) has coarser particles and high structure, which improves extrudability and reduces heat build-up.

Which grade is suitable for passenger tire treads

N220 and N330 are typically used for passenger tire treads, often in combination. N220 provides increased wear resistance, N330 offers a balance of strength and hysteresis loss.

Can N550 be used in mechanical rubber goods

Yes, N550 is widely used in hoses, seals, coverings and extruded profiles due to good extrudability and low heat build-up. For articles with high strength requirements, a combination with N330 may be required.

What is the shelf life of carbon black

Under proper storage conditions, the shelf life is typically 24 months from the date of manufacture. The material is hygroscopic, so after this period or if packaging is damaged, incoming moisture control is required.

What documents are required for carbon black import

Import requires a contract, invoice, packing list, manufacturer certificate of quality, safety data sheet, transport documents and a declaration of conformity (if required). The portal organizes the preparation of the document set and interaction with the customs broker.

Conclusion

Carbon black grades N220, N330 and N550 remain indispensable reinforcing fillers for tires and mechanical rubber goods, as well as functional additives for plastics and paints. Grade selection is determined by the required balance between reinforcement, hysteresis and processability: N220 for maximum wear resistance, N330 for versatile formulations, N550 for good extrudability and low heat build-up. For procurement teams, the practical task reduces to confirming batch conformity to ASTM D1765 or GOST 7885-86, controlling iodine number and DBP absorption, and organizing supplies with observance of storage conditions.

Contact Us

For procurement inquiries and supply chain organization, contact the portal team at info@apptrade.ru.