Anti-scorching agent PVI(CTP)
(1) most PVI are used to improve processing safety and reduce early vulcanization (coking) loss.(2) the extent to which processing safety can be improved with PVI depends on the type of promoter and the amount of sulphur used.It has been found that the activity of natural rubber is the highest in the process of sulfonamide sulfide under the conventional sulfur dosage.(H% V& 0.1 PHR PVI improves the safety of early vulcanization (coking) by 30% for natural rubber and 10% for styrene butadiene rubber, and the improvement is generally proportional to the dosage.
(3)PVI is significantly useful for almost all vulcanizable elastomers such as SBR, NBR, IR, IIR, EPDM and CR, and is also active for some polyacrylate rubber.PVI can replace NDPA with at least 4:1 ratio and traditional retardants such as organic acids (e.g. replace NDPA with 0.2phr PVI with 1.0phr).
(4) about 45 seconds before the end of the mixing cycle, accelerant, sulfur and PVI are added. Usually, the two-stage mixing cycle can be converted into a single-stage mixing cycle to save 30% of energy and time, and then dumped out for rapid cooling.The amount of PVI required depends on the temperature, but is usually 0.5 PHR.The dosage of 0.1phr is suitable for significantly improving the raw rubber
(5) due to the restriction of early vulcanization (coking), the rubber materials processed in the factory cannot be recycled, resulting in the generation of residual wastes.Generally, an appropriate amount of PVI can be added to mix with fresh rubber materials, and then early vulcanized rubber materials can be added. The dosage of PVI is effective when it is 0.3 PHR.
(6)PVI can also be used for faster and easier early vulcanization system, and the early vulcanization time is regulated by the processing amount of PVI.
(7) PVI must be used reasonably and it is suggested to reduce the dosage to avoid insufficient vulcanization.The characteristic of PVI is that there is a linear relationship between its high activity and the improvement of processing safety and its dosage.
Widely used in various promoters and vulcanizable elastomers.It can generally improve the processing safety of rubber (early vulcanization time), little or no effect on other processing or operation performance.