Introduction to common 8 types of rubber accelerators

Vulcanization accelerator is referred to as accelerator. All can speed up the curing reaction speed, shorten the curing time, reduce the curing reaction temperature, reduce the amount of curing agent capacity to improve or improve the physical and mechanical properties of sulfur adhesive compound, known as curing accelerator.

The application of accelerators can improve the production efficiency of rubber products, reduce the cost of products, improve the physical and mechanical properties of products, make the quality of thick products uniform, and improve the appearance quality of products and make the color bright.

At present, there are many kinds of accelerator used in the rubber industry. According to their properties and chemical composition, they can be divided into two categories: inorganic accelerator and organic accelerator.

The earliest use of inorganic accelerator, but because of the promotion effect is small, vulcanized rubber performance is poor, in addition to the other situation is still a small amount of use, the vast majority of occasions have been replaced by organic accelerator. Organic accelerators promote the effect of large, good vulcanization characteristics, vulcanized rubber has excellent physical and mechanical properties, so the rapid development.

With the continuous development of synthetic rubber varieties and uses, the existing promoters are increasingly complex, but at present the most commonly used but also dozens of.

Promoters are classified according to their chemical structure, the size of the promotion effect, and the appearance of the reaction with sulfide chlorine and acid base.

According to the different chemical structure, accelerators can be divided into thiazoles, thiuram, sulfoamides, guanides, dithiocarbamates, aldoamines, xanthates and thiourea and other eight categories.

First, thiazoles

This is an early breed of organic promoters. It is an acid accelerator. It is characterized by high vulcanization activity and good aging resistance and fatigue resistance. Therefore, it is widely used in the rubber industry and consumes a large amount. There are two main varieties as follows.

(1) 2 mercaptan benzothiazole trade name for accelerator M.

This product is light yellow powder, bitter taste, non-toxic, stable storage. For the general accelerator, natural rubber and diene general synthetic rubber with rapid promotion, vulcanization flatness is good, vulcanization critical temperature of 125℃, mixing the possibility of encephalitis burning. Easy to disperse in rubber, no pollution, but not suitable for food rubber products. The dosage of the first accelerator is 1~2 parts, and the dosage of the second accelerator is 0.2~0.5 parts. Can also be used for natural rubber plasticizing agent.

(2) dibenzothiazole disulfide trade name for promoter DM.

This product is light yellow powder, bitter taste, non-toxic, stable storage. Its characteristics and uses are similar to M, but the critical vulcanization temperature is 130℃. Above 140℃, the activity increases, has better after-effect, vulcanization operation is safe. It is often used with other accelerators to enhance its activity.

Two, the Tyuram class

Such accelerators are acidic. It is an overspeed accelerator. They include primary, disulfide and polysulfide kulams. Thiuram disulfide can be used for sulfur-free yellow vulcanization with vulcanizing agent. As an accelerator generally used as a second accelerator, with thiazole and secondary sulfonamide accelerator and used to improve the rate of vulcanization. When used with secondary sulfonamide accelerators, it can delay the reaction time of the rubber material, and the reaction can proceed particularly fast after the vulcanization, and the vulcanization degree of the rubber is relatively high. This production system is particularly important in low sulfur vulcanization.

The physical and mechanical properties and aging resistance of vulcanizates with thiuram accelerator are affected by the ratio of accelerator and sulfur dosage.

Generally speaking, the amount of sulfur is normal, the fixed elongation strength of vulcanized rubber is higher, and other physical and mechanical properties are better; When the amount of sulfur is low and the amount of promotion is large, the heat aging property of vulcanized rubber can be improved.

The most commonly used type of thiuram accelerator is tetramethyl Thiuram disulfide, the trade name is promoter TMTD, short for promoter TT. It can be used as accelerant, also can be used as curing agent. When used as accelerant dosage is generally 0.2~0.3.

Tertiary sulfonamides

This is a late-acting accelerator, acidic. It has the characteristics of long coking time and high vulcanization activity. Vulcanized rubber is relatively high degree of vulcanization, excellent physical and mechanical properties, aging resistance is quite good. The compound has a broad vulcanization flatness. Due to the development and application of synthetic rubber and the popularization and application of high dispersion furnace carbon black, a good delay accelerator is needed. Therefore, this kind of accelerant occupies a very important position and becomes the fastest developing and the most promising kind of accelerant in recent years.

At present, the use of a variety of promoters in the world, far to the secondary transverse amide class, among which a large number of applications are CZ, NOBS, NS, DZ and OTOS, they are mercaptan benzothiazole derivatives.

(1) N-cyclohexyl-2-benzothiazolidesulfamide trade name for accelerator CZ.

This product is light yellow powder, slightly odor, non-toxic, specific gravity is 1.31~1.34, melting point is not lower than 94℃, stable storage. The critical vulcanization temperature is 138℃, and it has the advantages of excellent coke resistance and fast vulcanization speed. This product has slight discoloration, spray cream, vulcanized rubber has excellent aging resistance. The general dosage is 0.5~2 copies.

(2) n-oxy-diethyl-2-benzothiazolidesulfonamide or 2- (4-morphinylthiolate) benzothiazole trade name NOBS accelerator.

This product is light yellow powder, non-toxic. The specific gravity is 1.34~1.40. Melting point is 80℃~86℃. It gradually decomposes when exposed to heat, so it should be stored at low temperature. When the storage time is more than 6 months, the coke dumping of the rubber material increases, the critical temperature of vulcanization is above 138℃, the coke burning time is longer than the accelerator CZ, and the operation is safer. This product is easy to disperse in the rubber, no spray cream, slight discoloration. The general dosage range is 0.5~2.5, and with 2~0.5 parts of sulfur yellow.

(3) N-tert-butylbenzothiazolsulfamide trade name for accelerator NS.

This product is light yellow powder with special smell. The specific gravity is 1.29, and the melting point is no lower than 105℃. Its performance and usage are basically similar to that of accelerator CZ, but its delayed effect is greater in natural rubber. Slight discoloration and contamination.

(4) N, N- dicyclohexyl -2-2 benzothiazole sulfamide trade name for accelerator DZ.

This product is brown yellow powder, odorless. The specific gravity is 1.2. Melting point not lower than 90℃. Stable storage.

This product disperses well in rubber. Vulcanization flat performance is similar to that of accelerator CZ. Comparison of dynamic physical and mechanical properties of vulcanized adhesives

Good, high elasticity and fixed elongation strength. However, vulcanized gum can not be used to make products in contact with food because of its bitter taste. Its dosage range is generally 0.5~1, sulfur for 2.5.