Shanghai Daoqin Plastics Co., Ltd.

   PP通称 polypropylene (PP), its resistant property can good, 也称“百折胶”. PP is types semi transparent, semi thermoplastic property plastics, tool has high strength, insulation property good, water absorption low, hot temperature degree high, density small, crystallization degree high and other features. modified filling material usually has glass fiber, material filler, thermoplastic property and other.

    different applications PP its flow property relatively large, generally use PP flow speed rate 介于ABS and PC between.

    1, plastics 处理

    pure PP is semi transparent white, can formed various color. PP color in generally injection molding machine upper can use masterbatch material. in 华美达 machine upper has add strong/high mixing/compounding function 独立塑化元 parts, can use color powder color. outer use products, generally use UV stabilizer and carbon filling. recycled material use ratio/proportion need ultra- 15%, 否则会引起 strong/high degree decline and separation understanding color. PP injection molding processing front generally especially drying 处理.

    2, injection molding machine selection

    for injection molding machine selection has requirements. due to PP tool has high crystallization property. using/adopting injection pressure relatively high and can more control electrical injection molding machine. clamping force generally 按3800t/m2 确定, injection amount 20%-85%即 can.

    3, mold and gate design

    mold temperature degree 50-90℃, for/regarding dimensions requirements relatively high use high mold temperature. type temperature degree ratio type temperature degree low 5℃ above, runner 直径4-7mm, gate long degree 1-1.5mm, can small 至0.7mm. gate long degree short good, is 0.7mm, deep degree is thick semi, wide degree is thick 两倍, mold cavity inner long degree increase. mold must has good gas property, gas deep 0.025mm-0.038mm, thick 1.5mm, need shrinkage 痕, need use large 而圆 注口 and runner, add strong/high thick degree need small （例如 is thick 50-60%）. homopolymer PP manufacturing product, thick degree can ultra- 3mm, 否则会 has bubbles （ thick products can use copolymer PP）.

    4, temperature degree

    PP melting point is 160-175℃, separation understanding temperature degree is 350℃, in injection processing temperature degree setting can ultra- 275℃. melt temperature degree most good in 240℃.

    5, injection speed degree

    is decrease/reduce internal stress and deformation, selection high speed injection, has and other grade PP and mold suitable （人 幔现 bubbles, gas marks ）. has surface 出现由 gate expand dispersion dark versus strip/profile 纹, need use low speed injection and relatively high mold temperature.

    6, back pressure

    can use 5bar熔胶 back pressure, color powder material back pressure can 适当调 high.

    7, injection and holding pressure

    using/adopting relatively high injection pressure （1500-1800bar） and holding pressure pressure （约 is injection pressure 80%）. large in full 行程 95%时转 holding pressure, use relatively long holding pressure time.

    8, products rear 处理

    is anti rear crystallization generate shrinkage deformation, products generally hot water 浸泡处理.