This is the use of two different types of acid accelerator, and the activity of the system is often curbed at a lower temperature (refers to the operating temperature), thereby improving the char performance, but at the vulcanization temperature, it can still play a rapid vulcanization role. For example, the combination of TMTD and M inhibits the activation of TMTD because part of TMTD is converted into DM, which improves the coke firing, and zinc dithiocarbamate is generated in the system, which plays the role of rapid vulcanization after the vulcanization starting point.
There are two common uses of AA. One is that the primary accelerator is a superspeed or ultra speed class (such as TMTD or ZDC), and the secondary accelerator is a quasi-superspeed class (such as M or DM). For example, in natural rubber, when the accelerator ZDC is used in l part alone, the scorch time is 3.5 minutes, and if the amount of 10% is replaced by the accelerator M, the scorch time can be extended to 8.5 minutes, while the vulcanization rate is unchanged, and the tensile strength of the vulcanized rubber is improved to a certain extent. The other is to use the accelerator M(or DM) as the main accelerator, TMTD as the secondary accelerator, and similar effects can be obtained after use. For example, the formula of the fiber body compound of the bias tire can be used with this method, and the vulcanization starting point is slow and the vulcanization speed is fast. The starting point of vulcanization is slow, and the rubber material has good fluidity before initial vulcanization, which is helpful to improve the adhesion between the rubber material and the fiber cord. The fast vulcanization speed ensures that these inner rubber materials can be vulcanized synchronously with tread rubber under late heating conditions. When the accelerator M(or DM) is used with TMTD, such as when the amount of M(or DM) is about 1 part, the amount of TMTD is generally 0.05-0.1 parts (up to 0.2 parts or more in synthetic rubber). If the amount of TMTD is too high, the vulcanization flatness will decrease, and the fatigue cracking resistance of vulcanized rubber will decrease.