Formula Investigation And Property Evaluation Of Curing Envelope

Curing envelope is widely used in the pre-cured process so as to fix the new pre-cured tread materials to the smoothed tire. It is desired that the curing envelope deserve times of expansion and collapsed aided by adding pressure. The hot permanent set of the envelope affects the quality of the tyres and the life cycle of the envelope decides the cost of recapping tyres. In this work, the formulas of curing envelope as well as new method to evaluating the Hot-tension-permanent-set of the Curing Envelope were explored.Formula investigation of the curing envelope included there parts:(1) IIR based curing envelope; (2) IIR/CR based curing envelope; (3) IIR/EPDM based curing envelope. Fundamental formula investigation refers to the mechanical properties and hot-tension-permanent-set.The effects of phenolic resin (HY-2055) dosage, curing time as well as the type and loading amount of Carbon Black (CB) on the stress relaxation, Hot-tension-permanent-set and mechanical properties of IIR and IIR/CR composites were investigated. And the qualitative connection between Hot-tension-permanent-set and Stress-relaxation rate was established firstly in this paper. The results of this work were described below:CR could be used to increase the thermal stability of the curing envelope. The Hot-tension-permanent-set property, vulcanization rate and mechanical property could be improved in balance by adding 5 phr CR.Partial replacement of IIR with EPDM could increase the Hot-tension-permanent-set property. The better results were obtained by using the recipes containing EPDM of 10-20phr. Mechanical and thermal aging properties of recipes decreased due to high EPDM ratio.It was discovered in this work that the more the resin dosage, the longer the curing time, the larger the CB particle size, the less the CB loading were, the slower the stress relaxation and the smaller the Hot-tension-permanent-set were.Considering the overall properties for preparing retreading tire Envelope, the optimum formulation is to add 10 phr resin HY-2055, more or less 50phrCB N330, with the vulcanization being conducted at 175±2℃for T90 min.