During long-term storage and use, rubber and its products will gradually become sticky due to the action of heat, oxygen, ozone, variable metal ions, mechanical stress, light, high-energy rays, and other chemicals and molds. Hard hair is brittle or cracked. This phenomenon in which physical and mechanical properties decrease with time and elasticity decreases is called aging. As the aging process progresses and develops, the properties of rubber and its products will gradually decrease, resulting in complete loss of use value. To this end, certain chemicals need to be added to rubber and its products to improve its resistance to the above-mentioned various destructive effects, delay or inhibit the aging process, thereby prolonging the shelf life and service life of rubber and its products. It is called an anti-aging agent.
1. The 3 products with the largest output of anti-aging agent
In 2016, the production of antioxidants reached 375,000 tons, accounting for 34% of the total output of rubber additives, ranking first among all rubber additives. Among all the antioxidants, the antioxidants TMQ, 6PPD and IPPD are the largest. Among them, the anti-aging agents TMQ, 6PPD and IPPD account for 80% of the anti-aging agents, which are the mainstream varieties of anti-aging agents.
◆Antioxidant TMQ (RD)
It is a general-purpose anti-aging agent with excellent anti-aging effect caused by heat and oxygen. It is widely used in various tires, hoses, tapes, rubber shoes, tape products and latex products, especially for the production of all-steel and semi-steel radial tires. It is one of the largest varieties and dosages of global anti-aging agents. Antioxidant TMQ is used in combination with p-phenylenediamine anti-aging agent 6PPD and protective wax to form a complementary protection system. It constitutes the typical protection system for rubber products and is the most important antioxidant formula in the processing of radial tires. It can inhibit the harsh conditions of oxidation, heat aging and weathering, but it has a poor effect on flex cracking. The main component of the antioxidant TMQ is a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline, in which the dimer content has the most significant effect on the oxidation resistance.
◆Anti-aging agent 6PPD (4020)
Natural rubber, butadiene rubber, isoprene rubber, styrene butadiene rubber, nitrile rubber, antiozonant and antioxidant for neoprene, excellent resistance to fatigue and ozone cracking, effectiveness between 4010 and 4010NA If used together with wax, it increases the static protection efficiency and has better protection against heat, oxygen, copper and manganese. When the temperature exceeds 35~40 °C, it will gradually form agglomerates. When the dosage is more than 2.5 parts, the rubber compound has slight softening effect, and the mechanical properties of less than 2.5 parts of the vulcanized rubber have no effect, and the tensile strength and the tensile strength decrease. It is especially suitable for use with anti-aging agent MB and heat-resistant rubber compound.
◆Antioxidant IPPD (4010NA)
A general-purpose anti-aging agent for natural rubber and synthetic rubber latex. It has excellent protection against ozone cracking and flex cracking; it is also an excellent protective agent for heat, oxygen, light and general aging. It also inhibits the aging of variable-valent metal ions, and its protective performance is more comprehensive than 4010 (CPPD). It will change color under sunlight, but it will not affect the performance, the melting point is low, easy to disperse, the solubility in rubber is larger than 4010, the frosting is smaller, so it can increase the dosage, and it is often used under the conditions of high dynamic and static stress. product. This product can be used alone, and the anti-aging agent AW or wax can reduce the dosage and improve the protection efficiency. In particular, it is used in combination with wax to improve the level of anti-static ozone cracking performance.
2. Anti-aging agents are divided into 5 categories according to their chemical structure.
Amine anti-aging agent (aldolamine anti-aging agent, ketoamine anti-aging agent, diaryl secondary amine, p-phenylenediamine), phenolic anti-aging agent (divided into monophenol, bisphenol, polyphenol), heterocyclic ring Anti-aging agents, phosphite anti-aging agents, other anti-aging agents (long-acting anti-aging agents, nickel salts, waxes).
◆ Aldehyde amine anti-aging agent. It is the reaction product of fatty aldehyde and primary aromatic amine. It is the oldest category of anti-aging agent. Aldehyde amine anti-aging agent is effective for aging caused by heat, oxygen and light. It has good dispersibility in rubber compound, but it is polluted. Suitable for light colored products. There are: antioxidant AH and AP.
◆ ketone amine anti-aging agent. Has the best anti-aging effect. There are: anti-aging agent RD, anti-aging agent AW, anti-aging agent BLE.
◆ Diaryl secondary amine anti-aging agent. This is one of the old varieties. It is still the first among all anti-aging agents, including: anti-aging agent D (D), anti-aging agent A (A), anti-aging agent DNP.
◆ p-phenylenediamine anti-aging agent. It includes the most important type of anti-aging agent, and it is also a promising anti-aging agent. There are: anti-aging agent 4010NA/IPPD, anti-aging agent 4020/6PPD, anti-aging agent 4010/CPPD, anti-aging agent ODA, anti-aging agent DPPD, anti-aging agent 7PPD, anti-aging agent 8PPD, anti-aging agent 3100/DTPD, anti-aging agent 445.
◆The protective effect of phenolic anti-aging agent and other anti-aging agents is not as good as that of amine anti-aging agent, but it has outstanding non-polluting properties, including: anti-aging agent 2246, anti-aging agent BHT (264), anti-aging agent SP, anti-aging agent BHA.
◆Heterocyclic anti-aging agent (including sulfur type), including: anti-aging agent MB, anti-aging agent MMB, anti-aging agent MBZ, anti-aging agent MMBZ. Anti-aging agent MB is an important variety of non-polluting anti-aging agents.
◆ phosphite anti-aging agent, there are: antioxidant TNP. The phosphite-based hydroperoxide decomposing agent and the radical scavenger act as auxiliary antioxidants in the polymer system, and are often used in combination with hindered phenols, and are rarely used alone.
◆ Long-lasting anti-aging agent. When the rubber product is used in a high temperature and vacuum environment, the antioxidant in the rubber may reduce or lose the protective effect due to volatilization. Another example is that a rubber product is used in contact with a liquid medium for a long period of time, because the extraction is faster or the protection effect is lost. Non-volatile or low-volatility, non-extracting or low-extracting anti-aging agents developed for this purpose include nitroso-diphenylamine (NDPA), allyl-substituted phenol (TAP) and the like according to the currently disclosed products.
◆ Nickel salt anti-aging agent (including sulfur type), including: anti-aging agent NDBC, anti-aging agent NDIBC, anti-aging agent NDMC. Both are green powder, which has the best ozone protection performance and also has protective effect on thermal oxygen aging and fatigue aging.
◆Wax anti-aging agent, when its dosage in the rubber exceeds the solubility in rubber, it will migrate to the surface after vulcanization to form a protective film, which can effectively prevent the static ozone cracking of the product. There are: paraffin, micro Crystal wax.
◆ Newly developed anti-aging agent. Tributyl urea derivative, lactam derivative, non-flexible (anti-flex) LAS (LAS-P) to styrene-substituted diphenylamine or 4,4'-stilbene-substituted diphenylamine, diisopropyl Phenyl substituted DPPD (DP), sulfurized triazine derivatives, 6-QDI, Durazone 37 and the like.