Mixing a small amount of accelerator in the rubber compound can greatly promote the reaction between the rubber and the vulcanizing agent (crosslinking agent), which can accelerate the vulcanization reaction speed, shorten the vulcanization time, reduce the vulcanization reaction temperature, and reduce the amount of vulcanizing agent. Or a compounding agent that improves the physical and mechanical properties of sulfur rubber is called a rubber vulcanization accelerator.
Due to the different types of rubber, the same accelerator has different accelerating effects on the vulcanization of different rubbers. Therefore, the vulcanization system of rubber should be selected reasonably. Therefore, it is necessary to have an accurate understanding of the classification of accelerators when designing formulas:
【Classification of accelerators】
1. Classified by chemical structure
1. Thiazoles: representative products M, DM, MZ
2. Sulfonamides: representative products CZ, DZ, NOBS, NS
3. Thiurams: representative products TMTD, TMTM, TETD, TBzTD, DPTT
4. Dithiocarbamates: Representative products ZDC, BZ, PZ
5. Guanidines: representative products DPG, DOTG
6. Thiourea: representative products ETU, DETU, DPTU
7. Aldehydes: representative products H, 808
8. Xanthogenates: representative products DIP, ZIX
2. Classified by market consumption or output
Divided into large varieties and small varieties, the ones with more consumption or output are called large varieties, and the ones with less are called small varieties.
1. Large varieties of accelerators: thiazoles, sulfenic acid amines.
2. Small varieties of accelerators: thiurams, dithiocarbamates, thioureas, xanthates.
3. Classification by promotion speed
Internationally, it is customary to compare the vulcanization speed of accelerators based on the effect of accelerator M on natural rubber.
1. Slow grade: thiourea, aldehyde amines, representative products ETU, DETU, H
2. Medium-speed grade: Guanidines, representative products DPG, DOTG
3. Quasi-speed grade: thiazole, hypoxanthamide M, DM, CZ, DZ, NOBS
4. Super speed class: thiuram class, representative products TMTD, TMTM, TETD
5. Super speed grade: dithiocarbamate, xanthate, representative products PZ, ZDC, BZ
Fourth, according to acid-base classification
1. Acid accelerator: thiazole, thiuram, dithiocarbamate, xanthate
2. Alkaline accelerators: guanidines and aldehyde amines
3. Neutral accelerators: sulfenamides and thioureas
Five, according to acid-base + promotion speed classification
1. Acid quasi-velocity: M, DM
2. Alkaline medium speed: DPG
3. Acidic super speed: PZ, ZDC
4. Neutral quasi-speed: CZ, NOBS, DZ
Six, classified by function
In terms of function, accelerators can be divided into primary accelerators and secondary accelerators (super accelerators).
1. Primary accelerator: the accelerator whose dosage and vulcanization characteristics occupy the main position. Including thiazoles (M, DM), sulfenamides (CZ, NS, NOBS, DZ), sulfenimides (TBSI). The primary accelerator usually delays scorching, has a moderate to rapid vulcanization rate, and a good modulus.
2. Secondary accelerator: activate with the main accelerator to speed up the vulcanization speed and improve the performance of the vulcanized rubber. Including guanidines (DPG), thiurams (TMTD, TMTM), dithiocarbamates (ZDC, BZ, PZ), dithiophosphates (ZBPD, ZDTP, TETD). Secondary accelerators usually cause the rubber compound to scorch easily and have a super fast vulcanization speed.
【Combined use of accelerator】
Purpose: To improve the effect of accelerator and for process needs, such as avoiding scorching, preventing blooming, and improving vulcanization flatness.
