硅橡胶厚功能制品的制备工艺研究

Preparation of Thick Functional Products of Silicone Rubber

研究了不同结构化控制剂搭配、硫化剂和减振填料用量对硅橡胶性能的影响,硫化时间、升温间隔对硅橡胶硫化效果的影响,脱模温度、放气量、工装设备对硅橡胶制品质量的影响。结果表明,采用高摩尔质量硅橡胶、气相法白炭黑,配合适量的结构化控制剂,可制备拉伸强度8 MPa以上、无结构化的硅橡胶;随着减振填料的大量填充,硅橡胶的力学性能呈下降趋势;随着硫化胶放气量的增加,大尺寸制品芯部有开裂的倾向。硅橡胶混炼胶用过氧化二异丙苯作硫化剂,采用分段升温、长时间硫化、保压降温工艺,可获得密实无缺陷的厚型制品。较佳工艺为:100份摩尔质量大于69×104g/mol的甲基乙烯基硅橡胶生胶、45份气相法白炭黑、6份羟基硅油、1份二甲基二乙氧基硅烷、1～2份DCP、2～5份氧化铁、10～40份减振填料,硫化时间选择厚制品157℃±1℃的传热时间,分段升温值15℃、升温间隔时间10～20 min、平均升温速率0.75℃～1℃/min,脱模温度根据制品厚度选择室温～80℃,放气量0.20%～0.27%,模具采用大间隙和小溢料槽。

The effect of the crepe-controlling agents, vulcanizers, and functional fillers on the properties of silicone rubber compounds and the effect of curing time and heating rate on the silicone vulcanization as well as the effect of the demoulding temperature, the volatile matter and equipment on the quality of silicone rubber thick products were explored. The results showed that when processing with high molecular weight silicone rubber, fumed silica as well as several crepe-controlling agents, the tensile strength of silicone rubber could be over 8 MPa without crepe effects. The mechanical properties deteriorated with the addition of functional fillers. While the volatile matter of the compound was increased, the silicone thick products inclined to crack in its core. By stepped heating, longtime vulcanizing and then isobaric pressure and gradul cooling, defect free thick products of silicone functional compounds could be prepared by using dicumyl peroxide as curing agent. The preferred method was as following： 100 parts of methyl vinyl silicone gum with molecule weight higher than 6.9 ~ 105 g/mol, 45 parts of fumed silica, 6 parts of hydroxyl silicone oil, 1 part of dimethyldiethoxylsi- lane, 1 -2 parts DCP, 2 -5 parts ferric oxide, 10 -40 parts functional filler, the curing time equal to the heat conducting time of thick product at 157℃ ±1℃, the temperature increment gap of 15℃, average heating rate 0. 75 - 1℃/min, demoulding temperature according to the products thickness in a range from room tem- perature to 80℃, volatile matter of 0. 20%-0. 27% , the mould fabricated with big clearance, and small o- verflow slot.