Shanghai Daoqin Plastics Co., Ltd.

transparent plastics due to light transmittance need high, requirements plastics products surface quality requirements 严格, can has 任何斑纹, gas 孔, 泛白. 雾晕, black spots, color, gloss and other defect, in injection molding process for raw materials, equipment. mold, product design, need separation attention/notes and 提出严格甚至特殊 requirements. its due to transparent plastics more is melting point high, flow property 差, therefore is ensure product surface quality, need in machine high temperature degree, injection pressure, injection speed degree and other process parameters as fine micro adjustment, make plastics can 充满模, also generate internal stress 而引起 product deformation and cracking. therefore from raw materials 准备, for equipment and mold requirements, injection molding process and product raw materials 处理几方面都 need 进行严格 操 as.

　　一, material and drying due to in plastics in has 任何一点杂质, can can effect/influence product transparent degree, therefore and 储存, 运输. add material process in, must attention/notes 密封, ensure raw materials dry 净. especially is raw materials in has water separation, add hot rear 会引起 raw materials 变质, therefore need drying, in injection molding 时, add material must use drying material 斗. also need attention/notes is drying process in, 输入 空 gas most good 应经 滤, remove wet, ensure 不会污染 raw materials. its drying process 如, transparent plastics drying process: material process drying temperature degree （℃） drying time （h） material thick degree （mm）备注pmma70～802～430～40pc120～130＞6＜30 using/adopting hot ring drying pet140～1803～4 using/adopting drying add material plant/unit is 佳

　　二, machine 筒, screw and its parts is anti raw materials and in screw and parts 凹陷处存 has material or 杂质, especially heat stabilized property resin in, therefore in use front, machine rear application screw agent dry parts, make its viscous has 杂质, has screw agent 时, can use pe, ps and other resin screw. 当临时停 machine 时, is anti raw materials in high temperature lower time long, understanding drop, will drying machine and machine temperature degree reduce, 如pc, pmma and other machine temperature degree need drop 至160℃ below/following. （ material temperature degree for/regarding pc应 drop 至100℃ below/following ）

　　三, in mold design upper attention/notes issues （包括 product design ） is anti 止出现回 flow 不畅, or cooling 不均造 formed plastics molding defect, generate surface defects and 变质, generally in mold design 时, attention/notes below/following 几点. a＝壁 thick amount uniform 一致, demolding degree need large; b＝ 渡部 separation 应逐步. slip 渡, anti has 尖角. generate, especially is pc product 一定不 need has 缺口; c＝ gate. runner can can wide large, coarse short, according to shrinkage cold process gate 位置, necessary add cold material 井; d＝ mold surface light 洁, coarse degree low （ most good low 于0.8）; e＝排 gas 孔. must 足够, and 时排出空 gas and melt in gas 体; f＝ remove pet outer, thick need thin, generally small 于lmm.