Rubber, as an important polymer material, is widely used in modern industry and daily life. From automobile tires to various types of seals, from accessories for electronic products to products in the medical field, rubber plays an indispensable role with its unique properties. However, to achieve the desired performance and quality of rubber, simply relying on the rubber itself is often not enough. This requires the use of various rubber additives to improve and optimize the characteristics of rubber. Although the proportion of rubber additives in rubber products is small, it can have a huge impact on the performance of rubber.
Antioxidant: Its main function is to delay the aging of rubber in the process of use. Aging will lead to a decline in rubber properties, such as reduced strength, poor elasticity, cracking and so on. Antioxidant realizes its function by inhibiting or slowing down the oxidation, thermal degradation, photodegradation and other reactions of rubber. For example, p-phenylenediamines are antioxidants, which have excellent antioxidant properties. It can react with free radicals in rubber molecules to interrupt the chain growth of aging reaction, so as to effectively protect rubber. In rubber products such as tires, hoses and other long-term use of products, the addition of antioxidants is very important.
Accelerator: plays a key role in the rubber vulcanization process. It can significantly accelerate the speed of vulcanization reaction, improve production efficiency, and improve the properties of vulcanized rubber. For example, the accelerator M (2-mercaptobenzothiazole) is a widely used accelerator. It can effectively promote the cross-linking reaction of rubber and vulcanize rubber in a short time. The mechanism of action of the accelerator is mainly by reacting with the vulcanizing agent to generate active intermediates, which are more likely to react with rubber molecules, thus accelerating the vulcanization process. Some accelerators have high activity and are suitable for rapid vulcanization; Some are less active and are suitable for situations that require a longer curing time.
Vulcanizing agent: The key additive that makes rubber produce cross-linked structure. Sulfur is one of the most common and traditional vulcanizing agents. When sulfur is mixed with rubber and heated, it triggers a vulcanization reaction that causes cross-linked bonds to form between rubber molecules. By vulcanization, rubber is transformed from a soft, viscous state into a solid state with certain strength, elasticity and wear resistance. Sulfur vulcanized rubber has good mechanical properties and heat resistance. However, sulfur vulcanization also has some limitations, such as the slow vulcanization rate, easy to produce vulcanization and so on. In addition to sulfur, there are some other types of curing agents, such as peroxide curing agents. The peroxide vulcanizing agent can be vulcanized over a wider temperature range, and the vulcanized rubber has better heat resistance and aging resistance. However, the cost of peroxide vulcanizing agents is relatively high, and in some cases may have some special effects on the properties of rubber.
Plasticizer: plays an important role in improving the processing properties and flexibility of rubber. It can reduce the viscosity of the rubber, make the rubber easier to process, and increase the elasticity and elongation of the rubber. Dioctyl phthalate (DOP) is a common plasticizer. It can interact with the rubber molecules, increasing the distance between the rubber molecules, thus making the rubber more soft and malleable. The selection of plasticizer needs to consider the compatibility with rubber, volatility, heat resistance and other factors. Some plasticizers may gradually volatilize or migrate during use, resulting in a decline in rubber performance.
Reinforcing agent: Carbon black, as one of the most important reinforcing agents, has a significant effect on the performance improvement of rubber. Carbon black has high specific surface area and special surface chemical properties, which can be closely combined with rubber molecules. When carbon black is added to rubber, it can effectively improve the tensile strength, wear resistance and tear resistance of rubber. For example, in tire manufacturing, carbon black is used in large quantities to enhance the wear and impact resistance of tires. The reinforcing effect of carbon black is closely related to its particle size, structure and surface activity. Different types of carbon black are suitable for different types of rubber and application scenarios. In addition to carbon black, there are other reinforcing agents, such as white carbon black. White carbon black is also used in some high-performance rubber products, which can provide special properties, such as good optical properties and low rolling resistance.
Flame retardant: give rubber a certain flame retardant performance to improve the safety of rubber products in the case of fire. Aluminum hydroxide is a commonly used flame retardant. When it is heated, it will decompose and produce water vapor, thereby absorbing a lot of heat and reducing the temperature of the rubber surface, and the generation of water vapor also helps to dilute the oxygen concentration and play a flame retardant role. In addition to aluminum hydroxide, there are other types of flame retardants, such as halogen flame retardants, phosphorus flame retardants and so on. Halogen-based flame retardants have better flame retardant effect, but may cause some environmental problems; Phosphorus-based flame retardants are relatively environmentally friendly, but may cost more.
Antistatic agent: mainly used to reduce the accumulation of static electricity on the surface of rubber products. In some cases, such as electronic equipment, chemical industry and other fields, static electricity accumulation may lead to discharge, interfere with the normal operation of equipment and even cause fire and other hazards. Antistatic agents usually achieve antistatic effects by forming a conductive layer on the rubber surface or increasing the electrical conductivity of the rubber. Common antistatic agents include cationic, anionic and non-ionic types. They can be surface-coated or added to rubber.
Coupling agent: plays an important role in improving the interface bonding force between rubber and other materials. Silane coupling agent is a common one. It can form chemical bonds at the interface of rubber and filling materials (such as glass fiber, metal, etc.), thereby improving the bonding strength of the interface. For example, in the bonding of rubber to metal, the use of silane coupling agents can significantly improve bonding strength and durability. The role of the coupling agent is not only to improve the interface binding force, but also to improve the dispersion and compatibility of the filling material in the rubber, so as to further improve the performance of the rubber.
Anti-coke agent: mainly used to prevent premature vulcanization of rubber during processing, that is, to prevent the occurrence of scorch phenomenon. Scorch will lead to a decline in rubber processing performance, such as reduced viscosity, poor fluidity, etc., affecting the smooth progress of production. The anti-coke agent can delay the start time of the vulcanization reaction, thus providing more ample time for rubber processing. Common anti-coke agents include organic acids, nitroso compounds and so on. Their mechanism of action is different, but they all achieve the anti-coke effect by inhibiting some steps of the vulcanization reaction.
Colorant: used to give rubber products a variety of colors to meet different appearance needs. Colorants can be divided into organic colorants and inorganic colorants. Organic colorants have bright colors and rich varieties, but they may have poor heat and light resistance. Inorganic colorants usually have better heat and light resistance, but the color selection is relatively small. When selecting the colorant, it is necessary to consider the stability of the color, the compatibility with the rubber, the impact on the performance of the rubber and other factors.
In short, rubber auxiliaries play a crucial role in the rubber industry. Their unique functions work in concert with each other, providing a strong guarantee for the production of high-performance, high-quality rubber products. With the continuous progress of science and technology and the continuous growth of market demand, the research and innovation of rubber additives will continue to advance, and inject new vitality into the development of the rubber industry. It is believed that in the future, rubber auxiliaries will continue to play an important role in promoting the rubber industry to a higher level.
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