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 整 injection molding parts process for raw materials, equipment, injection molding parts 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 relatively high temperature degree, injection pressure, injection speed degree and other process parameters need as fine micro adjustment, make injection molding parts material can 充满模, also generate internal stress 而引起 product deformation and cracking. therefore from raw materials 准备, for equipment and injection molding parts mold requirements, injection molding parts process and product raw materials 处理几方面都 need 进行严格 操 as. （一） raw materials 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 parts 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 lower table/sheet, transparent plastics drying process: material drying temperature degree （℃） drying time （h） material thick degree （mm）备注 PMMA 70~80 2~4 30~40 PC 120~130 >6 <30 using/adopting hot ring drying PET 140~180 3~4 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 injection molding parts 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 injection molding parts mold design 时, attention/notes below/following 几点. a）壁 thick amount uniform 一致, demolding degree need large; b） 渡部 separation slip, 并逐步 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） injection molding parts 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. （四） injection molding parts process 方面应 attention/notes issues (包括 injection molding parts machine requirements ） is decrease/reduce internal stress and surface quality defect, in injection molding parts process 方面应 attention/notes below/following 几方面 issues. a）应 selection specialized screw, belt/tape mono temperature 控射咀 injection molding parts machine; b) injection temperature degree in plastics resin separation understanding front lower, use relatively high injection wet degree; c） injection pressure: generally relatively high, 以克服熔 material viscosity large defect, pressure high generate internal stress formed demolding difficult and deformation; d） injection speed degree: in meet/satisfy 充模 情况 lower, generally low, most good can using/adopting slow fast slow more grade injection; e） holding pressure time and molding cycle: in meet/satisfy product 充模, generate 凹陷, bubbles lower; amount short, amount decrease low material in machine 筒停留 time; f） screw speed and back pressure: in meet/satisfy quality front lower, amount low, anti generate understanding drop can can; g） injection molding parts mold temperature degree: products cooling good bad, for quality effect/influence large, therefore mold temperature need can control its process, has can can 话, mold temperature high good. （五） other issues due to is need anti upper surface quality 恶化, generally injection molding parts amount less use demolding agent; use use material large 于20%. for/regarding remove PET outer, products 都应进行 rear 处理, remove internal stress, PMMA应 in 70－80t hot ring drying 4 small 时; PC应 in 清洁空 gas, 甘油, liquid 体石腊 and other add hot 110－135℃, time product 而定, most high need 10 more small 时. 而PET必 must di toward tensile 工序, can to good mechanical properties. modified additives （PA toughening agent, PC toughening agent, ABS toughening agent, PBT toughening agent, grafting PP, grafting ABS, film and pipe/tube increase agent and other ）.