Shanghai Daoqin Plastics Co., Ltd.

        PP+EPDM paint property can in very large degree upper and material property 质. due to PP本身 极 property very low, therefore main/primary paint combined force 取决于EPDM distribution 情况, requirements EPDM uniform distribution in product surface, ensure surface paint combined force 一致.

         process in, requirements in flow process in formed 适当 剪切 force, through PP and EPDM in flow speed degree upper 差异, will EPDM留 in product outer surface to paint requirements. in process control in due to requirements its it product quality, this comparison easy by 忽略. in front coating process in, 需验证 injection molding parts for coating property can effect/influence.

        PP+EPDM for/regarding product dimensions upper effect/influence main/primary is due to material mold shrinkage rate 引起. EPDM as is 橡胶体, in pressure function lower in can shrinkage property, therefore in injection molding pressure function lower, EPDM has shrinkage, mold opening rear product also in elastic property 释放.

        而PP as is crystallization material, in different temperature degree lower, crystallization speed degree different, formed shrinkage rate in 变化. in paint process in, 二次烘烤会引起PP again crystallization, therefore for product dimensions 而言, in comparison more.

         melt flow index:

         melt flow index is material flow property, melt flow index low, material flow difficult 不但会造 formed product surface more defect, also formed local dimensions small and other issues. melt flow index high, flow property good, make pressure lower, type inner melt amount for injection molding and holding pressure pressure separation 敏感, used for control dimensions process stability property 变差.

        材 material shrinkage rate:

        材 material shrinkage rate 偏差必然导致 product dimensional deviation. for/regarding PP+EPDM而言 remove material property outer, shrinkage rate also 取决于 product 形状, mold structure, injection molding speed degree, pressure and temperature degree. usually material supply provide material shrinkage rate is scope/range, if is certain value is for/regarding certain product 而言, has relatively large process mold shrinkage rate value.

        EPDM content:

         due to EPDM flow property relatively 差, 会引起 surface and dimensions upper defect. EPDM can by pressure shrink, formed local force in, more EPDM content formed process upper control difficult.

         slip powder content:

         slip powder 同样会起 to reduce flow property function, main/primary for product surface formed effect/influence, meanwhile if slip powder if blending non-uniform, also for reduce product paint property can.

         although, generally 而言材 material supply 商不会 provide material various formed separation content. is from material separation its it property can upper can 进行判断. fracture elongation large small, versus separation 取决于材 material in EPDM content, content high, elongation large.

         meanwhile, slip powder content high, strong/high degree high. therefore, in and other material property can lower, also need 考虑材 material process property can. usually 理想 材 material selection, 应该考虑 process 窗口尽 amount wide.

        随 currently for product dimensions requirements improve/increase, versus for using/adopting shrinkage rate comparison high material, is shrinkage high, process upper make product dimensions effect/influence 也会变 small.