Shanghai Daoqin Plastics Co., Ltd.

tpu线材 sink marks is what sink marks? is what has this type of phenomenon generate? has what methods? this issues is in understanding tpu线材时常会问答, 今天鼎誉材 material summary tpu线材 sink marks causes and remedy methods, for large in understanding tpu线材 时候 has 帮助.

1.当tpu线材 状态开始 from melt to cooling 时, will make 模塑工 parts overall dimensions shrinkage. although this type of shrinkage generally in per mille 之几英寸 scope/range, 但却足以 can obvious effect/influence parts and demolding, and most rear formed product appearance. if shrinkage non-uniform, will make 原本一 平整 工 parts bending or deformation. therefore in production tpu线材时, for requirements comparison 严格, due to this causes, therefore in production tpu线材 process in usually will sink marks property in inner.

2.以SBS is tpu线材(TPR)材 material, resistant water property is very good, generally tpu线材/TPR材 material sink marks rate 1.5~3% left right. polyester or polyether and other property material is tpu线材则不 resistant water,但 is generally is to water solvent 胀 而不 is shrinkage, but also use conditions has is 不确定. is different formulation different material property therefore production sink marks rate different tpu线材 production sink marks rate same.

3. conditions can significantly effect/influence shrinkage degree and essence. from high force very fast is low force 状态, shrinkage degree will increase. parts speed cooling and very high injection speed degree or pressure, can effect/influence shrinkage property.

4. in production tpu线材时, from design 方面考虑 to sink marks property, mold must processing ratio parts dimensions large. shrinkage value has and other to specific parts molding can 知. therefore, 事先保守一 总 is most good. certain tpu线材 ratio its it tpu线材 more is toward property, is 说也许会 in certain direction shrinkage ratio direction more 一. design mold 时, this factors must need in inner.

1. 放射纹 

说明: wet gas strip/profile 纹, U type 簇状拉 long strip/profile 纹, flow direction 呈放射状; relatively obvious is fine small 直线形式 

causes: pellets in 残余含 water amount high

remedy methods: drying process （ drying temperature degree, time and small 时 处理 amount ）检查 drying device device is by 污染

2. solvent combined strong/high degree 不足

说明: in solvent combined 线附近 products 失效 

causes: mold gas 不足, property flow property 不足, injection speed degree 不足, thick thin / flow long

remedy methods: mold gas, flow property, increase injection speed degree, increase melt and mold temperature degree, increase thick, or in necessary lower heavy new gate shrink short process/workflow long  

3. mold sticking

  causes: material selection and mold manufacturing sink marks rate combined 适, mold 倒扣（ deformation ）, surface thin and light slip, products injection molding 满, mold temperature high  

  remedy methods: selection combined 适 材 material, mold, reduce holding pressure time combined scope/range, cooling add long

4. yellowing  

causes: dry temperature degree high 久, material selection combined 适, testing methods has 差异

remedy methods: pellets dry 说明, combined dry; more add requirements selection combined raw materials; selection positive testing methods

5. 起斑点 

causes: material and masterbatch versus solvent property 不佳, use combined solvent agent scratch products surface

remedy methods: selection combined masterbatch or raw materials, use combined solvent agent scratch （建议酒精）