The most commonly used is carbon black, which has the functions of reinforcement and filling. There are many materials that are used for reinforcement and can also reduce costs such as fillers.
1.1 Carbon black
Carbon black is a widely used chemical product, which can be used in rubber, resin, printing ink, paint, wire and cable, battery, paper, pencil, pigment and other products. The main use of carbon black is in the manufacture of tires and various rubber products. About 70% of the global carbon black is used in tires, 20% is used in other rubber products, and less than 10% is used in plastic additives, dyes, printing inks and other industries. In the share of rubber products, half is used in the manufacture of auto parts, such as V-belts and shock-absorbing rubber. Therefore, about 80% of carbon black is consumed in the automotive industry.
Generally speaking, the world carbon black industry has entered a mature stage, and its production technology is mainly developed in several directions such as single furnace capacity/scale, specialization of carbon black products, comprehensive energy saving, and consumption reduction, and environmental protection and safety.
(1) High performance and low hysteresis loss carbon black
In order to meet the development of tire products, especially the needs for high-performance tires and green tires, major foreign carbon black companies have developed many new varieties of high-performance and low-hysteresis loss carbon blacks. The so-called high-performance carbon black has the common characteristics of small particle size, suitable structure, narrow aggregate distribution size, and high surface activity. The common characteristics of low hysteresis loss carbon black are high structure, wide aggregate size distribution, and high surface activity. Among them, some varieties developed earlier, such as N134 and N358, have been incorporated into the ASTMD1765 standard and have been widely used by tire factories. The new varieties researched and developed in recent years have not been included in ASTM standards, nor have their chemical indicators been announced. Only some products can be found in the manufacturer’s product catalog, and the description of their application performance can be seen. These new varieties are currently being promoted and applied.
(2) Nanostructured carbon black
Low hysteresis loss of carbon black is the focus of development, which is determined by the development trend of the downstream industry of carbon black, the tire industry, to develop “green tires”. As long as carbon black companies and tire companies work closely together, low hysteresis loss carbon black will enter the stage of large-scale application.
Nanoscale carbon black is manufactured using an improved furnace process. Compared to conventional ASTM carbon blacks, nanoscale carbon blacks have higher surface roughness and greater surface activity. The larger surface activity is mainly associated with smaller crystalline particles that are highly disorderly and cross-linked. This crystalline particle has a large number of edges, making it an active field with particularly high surface energy, which produces strong mechanical/physicochemical interactions between the carbon black and the polymer. Increasing the filler-polymer interaction reduces hysteresis losses and heat generation under dynamic deformation. The natural rubber tread compound for truck tires filled with 52 parts of ASTMN356 carbon black and the corresponding E-1670 nanoscale carbon black can greatly reduce hysteresis loss and heat generation, thereby reducing rolling resistance. Due to the low DBP value of nanoscale carbon black, the 300% tensile stress of the vulcanizate is slightly lower.
(3) Conductive carbon black
Since the conductive/static properties are the basic properties required by many rubber products, the development prospect of conductive carbon black cannot be ignored. The development of conductive carbon black is mainly developed along two series conductive carbon black for rubber and conductive carbon black for plastic.
1.2 Silica
Silica is also known as hydrated silica, active silica, and precipitated silica, with the molecular formula SiO2·nH2O. It is a highly dispersed amorphous powder or flocculent powder with lightweight, high electrical insulation, porosity, and water absorption. Its original particle size is less than 3μm, so it has a large surface area, good reinforcement and viscosity enhancement, and good dispersion, suspension, and vibration liquefaction characteristics. It has been widely used in plastics, rubber, paper, coatings, dyes, and inks. In several fields, especially in the rubber industry, silica ranks first for its superior reinforcement and transparency. However, due to the presence of active silanol groups on the surface of silica, adsorbed water, and acid regions on the surface caused by the preparation process, silica is hydrophilic, and it is difficult to infiltrate and disperse in the organic phase. In the rubber vulcanization system, It is not well compatible with polymers, thus reducing the vulcanization efficiency and reinforcing properties, making it unusable in some special fields. The modified white carbon black has improved surface activity, improved dispersibility, and compatibility in the organic phase, thus greatly broadening the application field of the product and improving the high added value of white carbon black.
Silica can be divided into the physical method and chemical method according to its method. The white carbon black products prepared by physical methods are not of high grade, and the white carbon black fillers required by the rubber industry are usually produced by chemical methods. The chemical method can be divided into dry pyrolysis method (including gas phase method and electric arc method) and wet method, and the wet method can be divided into precipitation method (including sulfuric acid precipitation method, hydrochloric acid precipitation method, nitric acid precipitation method, carbon dioxide precipitation method) according to its formation characteristics. method and hydrothermal method) and gel method (including ordinary dry type and aerogel type). At present, there are two main production processes for silica at home and abroad. One is the gas phase method using silicon tetrachloride as the raw material. The fumed silica is obtained, which is then coagulated into floc, and then separated and deacidified to obtain the product. Silica produced by the gas phase method is a high-quality product with high purity and small particle size and is generally used as a fine filler. However, it is limited due to the high price of raw materials, long reaction process, large energy consumption in the production process, and high product price. The other is an acid precipitation method using water glass as raw material, that is, Si2 powder that is loose, finely dispersed, and precipitated with a floc-like structure is obtained from water glass through acidification. The preparation of white carbon black by acid precipitation has a simple production process and low product cost, but the product has a large particle size, low activity, and low product quality.
European tire manufacturers proposed the concept of green tires in 1992, so the development status of fillers began to change. Through the use of special polymers and silica/silane systems, high wet traction and wet braking performance can be achieved, and fuel consumption can be reduced by 5% by reducing rolling resistance. The silica/silane filling system used in the formulation of car tire tread compounds in the European original tire market (OEM) has reached more than 80%. The dramatic improvement in the performance of modern winter tires also relies primarily on the use of silica/silanes in the tread compound.
In addition to using silica as the main filler for car tire tread compounds, the use of silica for carcass rubber can further reduce heat generation and rolling resistance. By using special high-dispersity silica, combined with high-structure fine-particle carbon black, the application of silica can be expanded, and they can be used in truck tires. With this optimal filling system, the main performance requirements of truck tires can be met, namely, reducing tire hysteresis loss, thereby reducing rolling resistance, and maintaining wear resistance.
1.3 Carbon black-silica dual-phase filler
Carbon black-silica dual phase filters are produced using a unique technology developed by Cabot Corporation. The traditional carbon black is composed of 90%-99% carbon element, oxygen and hydrogen are other main components, and this new filler is composed of carbon black phase and silica phase dispersed in the carbon black phase. Its main feature is to improve the interaction between the rubber and the filler in the hydrocarbon elastomer and reduce the interaction between the filler and the filler. The filler can improve compound properties, especially the relationship between hysteresis loss and temperature of tire tread compounds, greatly reduce rolling resistance and improve traction, but does not reduce the wear resistance of conventional carbon blacks.
Carbon black-silica dual-phase filler (CSDPF) has been sold in the market under the trade names ECOBLACKTM and CRXTM2XXX series, so at the same time, there are also CSDPF2000 series and CSDPF4000 series products. Differences between CSDPF2000 and 4000 include silica distribution, silica surface coverage, and silicon content. CSDPF4000 has higher silica surface coverage and silicon content than CSDPF2000. This can be seen from the change in silicon content and the change in the surface area upon extraction with hydrofluoric acid (HF). During the HF extraction, the silica was dissolved by the carbon black phase that remained unchanged. From the fact that a large amount of silica still exists during the HF extraction of CSDPF, and the surface area increases sharply, it can be seen that CSDPF2000 silica is distributed throughout the aggregates. In contrast, the surface area of CSDPF4000 did not change much, and almost no silica remained after HF extraction. This indicates that CSDPF4000 aggregates. The white carbon black in it only stays on the surface.
Both CSDPF2000 and 4000 have higher filler-polymer interactions and lower filler-filler interactions when blended with hydrocarbon polymers compared to conventional carbon blacks and silicas. For filled compounds, the elastic modulus decreases with decreasing strain amplitude, which is known as the “Payne Effect”. The Payne effect, mainly controlled by filler-filler interactions, is often used as a measure of filler network structure. While both CSDPF 2000 and 4000 perform between carbon black and silica from a chemical composite point of view, what is actually observed here is that both new fillers have the lowest Payne effect.
The use of CSDPF2000 can improve the friction coefficient between the truck tire tread and the road surface, thereby improving the tire’s anti-skid performance on wet roads. The high silica coverage of CRX4000 can reduce micro-elastic hydrodynamic lubrication, which is beneficial to improving the anti-skid performance of car tires on wet roads. Therefore, in order to improve the comprehensive performance of the tire tread, CSDPF4000 can be used in the tread compound of passenger car tires, and CSDPF2000 can be used in the tread compound of truck tires.
1.4 Other fillers
(1) Modified Kaolin
Shanxi Jinyang Calcined Kaolin Co., Ltd., a Sino-foreign joint venture, has carried out special treatment on coal-based kaolin to increase the specific surface area, and then carried out surface modification treatment, which can greatly improve the reinforcing effect of rubber. It is used in automobile tires, EPDM, and other rubber products. In applications, the reinforcing properties of carbon black or silica are achieved or even surpassed in some respects.
(2) Fly ash type rubber reinforcing agent (XRF)
Filling of glass microbeads separated from fly ash into polyvinyl chloride (PVC) improves performance and reduces cost. A new type of rubber reinforcing agent (XRF) with fly ash as the main material developed by the Beijing University of Chemical Technology has been applied in Beijing No. 2 Rubber Factory. A large number of experiments have proved the application performance of the new rubber reinforcing agent (XRF) in natural rubber and synthetic rubber (styrene-butadiene rubber, nitrile-butadiene rubber, EPDM rubber, neoprene rubber, etc.) has completely reached the same replacement semi-reinforcing performance. level of carbon black. This technology not only solves the environmental pollution caused by the accumulation of a large amount of fly ash but also makes a significant contribution to saving resources.
(3) Attapulgite modified clay
The chemical composition of attapulgite is silicon and aluminum oxides, with a small amount of iron, calcium, and manganese oxides. The white fibrous crystals are semi-reinforcing fillers, which can make the surface of the extrusion calendering compound smooth. The new high-quality rubber reinforcing agent attapulgite modified clay can increase the tensile stress of rubber products by 300%, improve the elongation at break, fast powder eating speed, and dust is not easy to fly. It has high whiteness, high dispersion, and high covering power. Features. Adding this product to rubber products can not only improve the appearance quality, and delay the aging speed, but also resist acid and alkali corrosion and reduce the cost. It is an excellent rubber reinforcing agent. It can be widely used in rubber transmission belts, tires inside and outside of automobiles, and other rubber products.
(4) Modified hard clay
Hard clay has a semi-reinforcing effect on rubber, which can improve the mechanical properties of the vulcanizate. Soft clay has no reinforcing effect on rubber. The clay is modified with stearic acid, vinyl silane, hydrogen silane, and titanate coupling agent to make its surface hydrophobic, which can improve the tensile strength and tensile stress of the rubber compound, and reduce heat generation and compression. Permanent deformation, its reinforcing performance is equivalent to that of silica, and its aging performance is better. The effect of the new reinforcing agent – superfine activated clay SFAC is equivalent to that of semi-reinforcing carbon black under the condition of equal replacement.
(5) DSI rubber reinforcing agent
Ultrafine powder processed from rice husk as raw material, rubber reinforcing agent made by coupling activation, mainly suitable for glass, paint, paper, rubber, and plastic products.
(6) Plastic-based rubber reinforcing filler
Based on polyolefin plastic, it is combined with heavy CaCO3 powder, calcium and magnesium powder, and various high-efficiency surfactants, and adopts multi-layer coating technology to produce high-performance plastic-based rubber reinforcing filler. The agent has good fluidity and can be applied to a variety of rubber miscellaneous parts with natural rubber as the main compound, such as rubber V-belts, rubber seals, rubber rollers, rubber gaskets, and rubber pipes, Rubber sheets, etc.
(7) Lignin-type rubber reinforcing agent
Lignin is obtained by direct modification in the waste liquid of papermaking and pulping. A new rubber processing technology is used to achieve molecular-level penetration and cross-linking between rubber and lignin so that rubber and natural polymer compounds ( The alloy composed of lignin) has excellent comprehensive properties. Its mechanical properties are comparable to those of high wear-resistant furnace carbon black, and its proportion in rubber can be twice as high as that of carbon black.
(8) Nano zinc oxide
Nano-zinc oxide is a white or slightly yellow fine powder, which is easily dispersed in rubber and latex. It is a reinforcing agent, active agent, and vulcanizing agent for natural rubber and synthetic rubber, and also a colorant and filler for white rubber. . After adding active zinc oxide to the rubber compound, it can make the rubber have good abrasion resistance, tear resistance and elasticity.
(9) Sepiolite rubber reinforcing agent
The chemical composition of sepiolite is a hydrate of silicon oxide and magnesium oxide, with a small amount of aluminum and iron oxides. It is used as a reinforcing agent in light-colored rubber products, and its performance is only second-born silica. When sepiolite powder is treated with silane, its reinforcing performance is close to that of white carbon black, and the price is only half of that of white carbon black. It is resistant to acid and alkali, and chemical corrosion, and has good dispersion performance in rubber and plastic products. It is an ideal filling and reinforcing agent in rubber and plastic products. The use effect in natural rubber is better, which can greatly reduce costs, improve product quality, and economic benefits.
(10) Magnesium carbonate
Magnesium carbonate is mainly used as a filler and reinforcing agent for rubber products, which can increase gloss, whiteness, and high-temperature resistance, and is a thermal insulation material.
(11) Modified bentonite
Modified bentonite is prepared from natural bentonite, modifier, and other additives. It has strong adsorption and cation exchange capacity. It is mainly used as a filler and reinforcing agent for various rubbers, which can improve the performance of rubber products. , reduce the cost of rubber products, improve the bonding strength of rubber and cord, and the processing performance of rubber.
(12) Zeolite powder
Zeolite powder is a non-metallic mineral. Due to its very unique mineral structure, it can be used as a filler and reinforcing agent for various rubbers to improve the performance of rubber products.
(13) High active silica coupling agent 481 reinforcing agent
High-activity silica coupling agent 481 reinforcing agent is a new type of rubber industrial material developed by Haicheng Xinli Plastic Co., Ltd., Liaoning Province. It is non-toxic, tasteless, and microscopically flaky. The product has a reinforcing effect and high activity and is a good reinforcing auxiliary material for the rubber industry. Its product properties have strong hydrophobicity, stable chemical properties, heat resistance, and light resistance.
(14) Mica powder
Sericite has a reinforcing effect, can be used as a substitute for some semi-reinforced carbon black, and can also be used as a release agent. Because it belongs to the monoclinic system, its crystals are in the form of flakes, so it can improve the damping performance of rubber. It has good heat resistance, acid resistance, and electrical insulation properties, as well as the function of protecting ultraviolet rays and radioactive radiation, and can be used for special rubber products.
(17) Gangue powder
The chemical composition of coal gangue five is similar to kaolin, which is a mixture of alumina, silica, and magnesia. Its volatile content is as high as 27%, and it has a semi-reinforcing effect, commonly known as silica-alumina carbon black. It is easy to be mixed into rubber and has good dispersibility. It can be used as a reinforcing agent to replace part of carbon black.
