Such accelerators are condensation products of aliphatic aldehydes or amines (aliphatic or aromatic amines). It is acidic. When the varieties are different, their vulcanization activity and the obtained vulcanization performance are quite different. Its activity generally ranges from quasi-super to slow speed. It has good flatness, and the scorching time is not long. The biggest feature is the excellent aging resistance of the obtained vulcanizate. Among them, accelerators with weaker activity (such as hexamethylenetetramine) are mostly used as the second promotion of thiazole or sulfenamide accelerators. Only the butyraldehyde aniline condensate is a strong accelerator, and it is used as the first accelerator when it disperses with thiuram accelerators.

(1) The trade name of hexamethylenetetramine is accelerator H. This product is white to light yellow crystalline powder, almost odorless and bitter in taste. It is irritating to the skin. The specific gravity is 1.3. When heated to 263℃, it will sublime and partially decompose. Slightly deliquescence. The critical temperature is 140°C. When the vulcanization temperature is low, it is not very active and the risk of scorching is small. Used as a second accelerator. Does not change color, does not pollute, and is not easy to decompose. Mainly used for transparent and thick-walled products.

(2) Condensate of n-butyraldehyde and aniline The trade name is accelerator 808. This product is brown-red or amber viscous oily liquid with a special smell. The specific gravity is 0.94~0.98. Long-lived in the air, the color will become darker and the specific gravity will increase. But the efficiency remains the same. Isolate the air and keep it stable. The vulcanization flatness is high, the critical temperature is 120℃, and the most suitable vulcanization temperature is 120~160℃. Good dispersibility in dry glue. Suitable for rubber and hard rubber containing reclaimed rubber.