Shanghai Daoqin Plastics Co., Ltd.

crystallization property plastics has obvious melting point, solid separation 子呈规则排列. 规则排列区域称 is 晶区, 无序排列区域称 is non 晶区, 晶区 占 percentage is crystallization degree, usually crystallization degree in 80% above polymer is crystallization property plastics. Common crystallization property plastics has polyethylene (PE), polypropylene (PP)  , polyamide (PA) （ nylon ）, PBT resin.

crystallization type plastics crystallization degree and crystallization effect/influence to products material 理, mechanical properties. molding cooling speed degree slow, has crystallization 进行, can improve/increase crystallization degree. therefore, need to mechanical properties excellent and surface gloss good products for/regarding mold temperature control is is important.

is let cooling speed degree slow, 以便充 separation crystallization, must improve/increase mold temperature degree, can 避免 会 make molding cycle long. crystallization type plastics in its melting point 附近时 ratio 容变化 relatively large. has material in cooling has 一定程 degree shrinkage, generally crystallization type plastics tool has ratio non crystallization type plastics molding shrinkage large features. therefore, its products easy generate deformation, its thick products easy generate 凹痕, large made parts has can can warpage, in relatively thick separation formed 凹痕.

总之, not only 应考虑 to mold temperature degree high low, but also need attention/notes to products separation must uniform cooling solid （ or uniform crystallization ）, this non important.  

（1） polyethylene (PE)  

polyethylene (PE) generally in molding flow property good. can is its heat stabilized property 担心. however, it separation orientation property strong/high, therefore products easy generate deformation.  

high density polyethylene (PE) tool has crystallization temperature degree. generally 说, requirements relatively high injection pressure and injection speed degree. especially is for/regarding thick products, injection speed degree versus important, it can improvement products surface gloss, anti products warpage and reduce molding shrinkage.  

（2） polypropylene (PP)       

polypropylene (PP) has very more and polyethylene (PE) versus 似, flow property positive ratio material temperature degree, in 280℃ left right 时, resin aging, requirements temperature degree control in 270℃ below/following is 宜. its separation orientation property relatively strong/high, in relatively low temperature degree molding 时, due to its separation orientation, easy generate warpage, and other deformation, must attention/notes control temperature degree.  

（3） polyoxymethylene (POM)        

polyoxymethylene (POM) （POM） has homopolymer and copolymer, is flow property good resin. type resin easy hot separation understanding, must attention/notes control molding temperature degree. POM copolymer ratio POM homopolymer heat stabilized property good, it can in high temperature degree conditions lower molding processing, 但此材 material in material inner time long, 否则, 会发生 hot separation understanding make products color 泽发黄.

（4） polyamide (PA) （ nylon ）

polyamide (PA) viscosity temperature degree 变化极 is 敏感. it and its it thermoplastic property plastics different, nylon melting point comparison obvious. polyamide (PA) in its melting point upper molding, therefore its molding temperature degree must ratio generally material need high. due to nylon wet property relatively large, must 预先充 separation drying. however, in 90℃ above drying 便会变 color, must add attention/notes.

（5）PBT resin  

PBT resin （ polybutylene terephthalate (PBT) ） and PET（ polyethylene terephthalate (PET) ）均 belongs to saturated and polyester （ thermoplastic polyester ）. PBT resin features is melt viscosity low, molding property good. it crystallization speed, solid fast.  

PBT and PET resin generally more using/adopting glass fiber reinforcement improve/increase property can. in 此, introduction non reinforcement resin molding key points. its add hot material generally is 230～270℃（ flame retardant grade is 250℃）. mold temperature degree is 40～90℃, tube/pipe in relatively low mold temperature can molding, is to surface gloss products, using/adopting relatively high mold temperature. injection pressure scope/range is 50～130 MPa.

因 resin solid speed, therefore injection speed degree fast, make products appearance good and has improve/increase property can. in addition, due to wet resin melt 时, 会发生遇 water separation understanding rear 果, make products 变脆, therefore in processing front must resin drying.