1.What is a combination of accelerators?

When accelerators are used together, usually one accelerator is the main accelerator (called the main accelerator or the first accelerator), and the other accelerator is the secondary accelerator (called the secondary accelerator or the second accelerator). The amount of the main accelerator is larger, and the amount of the secondary accelerator is smaller (generally about 10% to 40% of the amount of the main accelerator).

2.What are the types of accelerators used in combination?

 Accelerators are divided into three categories according to acidity and alkalinity. One is acidic accelerator (represented by letter A): including thiazole, thiuram, dithiocarbamate, xanthate; the other is alkaline accelerator (represented by letter B): including guanidine Classes and aldehyde amines; three are neutral accelerators (represented by the letter N): including sulfenamides and thioureas. Accelerators are classified into AB, AA, BB, NA, NB, NN, etc. according to the combination of acidity and alkalinity, but the combination of acid-base (AB), acid-acid (AA), and medium acid (NA) is commonly used.

Accelerators are divided into five categories according to the vulcanization speed. Internationally, it is customary to compare the vulcanization speed of accelerators based on the effect of accelerator M on natural rubber. Slow grade: aldehyde amines, thiourea; medium-speed grade: guanidine; quasi-super-fast grade: thiazole, hypoflavin amide; super-fast grade: thiuram; super-super-fast grade: dithiocarbamate, yellow Orthoates.

3.What is the combination skill?

Generally, acid accelerator (A) type or neutral accelerator (N) type are used as main accelerators, namely thiazoles and sulfenamide accelerators. Thiurams are generally used as primary accelerators in effective and semi-effective vulcanization systems. As the main accelerator, dithiocarbamate accelerators are commonly used in latex products and butyl rubber. Secondary accelerators generally use alkaline accelerators such as DPG, H, etc. Its function is to activate and promote each other. When sulfenamides are used as main accelerators, secondary accelerators are generally not selected. Because this accelerator can decompose accelerator M and amine compounds at the vulcanization temperature, M is an acid accelerator, and the amine compound is a basic accelerator. An acid-base (AB) combination system is formed, but in order to speed up the vulcanization rate, a small amount of accelerator DPG or thiuram-type accelerator can be used in combination. The amount of accelerator DPG is generally 10% of the main accelerator. When the amount is too high, the vulcanization rate will tend to decrease.