Shanghai Daoqin Plastics Co., Ltd.

 PC/ABS alloy is types property can excellent engineering plastics, improvement PC force cracking property, processing property, meanwhile tool has excellent heat resistant property, impact resistant property, chemical resistance and dimensional stability . 无卤 flame retardant PC/ABS不 using/adopting flame retardant, more green environmental protection, flame retardant rating can 达1.5mm V0, 2.0mm 5VB and 3.0mm 5VA, 甚至0.75mm V0 and other grade, widely used in electrical 脑显示 device outer housing/shell, 笔记本 outer housing/shell and other IT product and parts, printing machine and other office equipment outer housing/shell.

图1: OA housing/shell 体

无卤 flame retardant PC/ABS can use processing equipment injection molding or extrusion molding, processing and other, injection molding application most more .

its features lower:

图一 无卤 flame retardant PC/ABS流变 features 图

flame retardant PC/ABS due to has PC formed separation and flame retardant, small amount water separation easy 导致PC in high temperature molding processing process in generate hydrolysis, and separation hot 导致部 separation degradation and small analysis 出, formed products generate silver streaks, 发黄, Color Difference and product 脆, cracking and other appearance and strong/high degree issues, therefore, processing in need control good related step/link.

一, material drying

flame retardant PC/ABS resin absorption gas in water separation, water amount is 0.2~0.3% between. is make injection molding products to most 佳效果, decrease/reduce degradation can can property, PC/ABS in molding processing front must drying, make material water amount drop 至0.04% below/following, most good in 0.02% below/following, improve/increase processing stability property and mechanical properties. HAC series PC/ABS drying time and moisture content 关系见 lower 图:

图二 无卤 flame retardant PC/ABS drying time and water separation content trend 图

usually, flame retardant PC/ABS resin in temperature degree lower drying 4~6 small 时, can to moisture content. drying time and drying equipment has 关, most long drying time can ultra- 48 small 时, 否则材 material has degradation color can can.

commonly used drying equipment has types: 箱式 drying machine, material drying machine and remove wet drying machine . flame retardant PC/ABS建议 use remove wet drying machine drying.

二, injection molding equipment selection

确定 injection molding machine specifications 时, remove clamping force outer, for flame retardant PC/ABS应尽 amount selection most large injection molding amount low machine 台. injection molding weight （ has type 腔, runner and 注道） and other injection molding machine most large injection molding amount 50~80%时, generally can obtain most 佳效果. use large material machine 时, small injection amount formed resin time necessary long, resin degradation. if must in temperature degree scope/range high temperature 段进行 injection molding, selection relatively small injection molding machine material amount, injection molding amount large most large injection molding amount 60%, shrink short material time, reduce degradation can can property. usually, flame retardant PC/ABS most long hot time small 于10 separation 钟, most hot time small 于5 separation 钟.

图2: PC/ABS材质充 electrical 宝

三, injection molding process parameters setting

1, molding temperature degree

molding temperature degree setting is ensure flame retardant PC/ABS充 separation is 基准, amount use low temperature 区域, anti material degradation. molding temperature degree increase obvious reduce flame retardant PC/ABS viscosity, increase resin flow property, make flow 距离变 long. upper, use molding temperature degree upper 限时, make 熔胶滞留 time can can short, degradation. flame retardant PC/ABS molding temperature degree generally is 230~270℃.

2, screw speed and back pressure

high screw speed 会导致 large hot, from make melt material temperature degree large large high setting temperature degree, has can can 导致材 material degradation. 同样, high back pressure 也会导致 large hot. generally in cooling time inner amount formed amount setting screw 转数. meanwhile need 考虑材 material 塑化状态, screw 回转时发生 剪切 hot, amount time stability property and most small amount stability property, 建议转 speed is 30~70rpm. back pressure 调校应视 raw materials property can, drying 情况, product structure and quality 状况而定, flame retardant PC/ABS back pressure generally in 3-10kg/cm2. product surface has less silver streaks, mixed color, sink marks and product dimensions weight large 时, can increase back pressure; 射嘴出现漏胶, 流涎, material hot separation understanding, product color and material slow can 考虑适当 decrease low back pressure.

3, injection molding speed degree

selection injection molding speed degree 时, main/primary products appearance, mold gas and type inner resin flow retardant force. relatively fast injection molding speed degree, generally make process/workflow add long, combined thin products, formed relatively good surface light degree, fast injection molding speed degree generate strong/high 剪切导致材 material degradation. slow speed injection molding speed degree can 帮助避免 gate 白晕, 喷射痕 and flow marks and other defect. according to product and mold structure using/adopting separation 段阶梯式 speed degree setting, ensure 充填顺畅 and products appearance.

4, holding pressure pressure and time

holding pressure pressure and time setting is combined 理, effect/influence made parts internal stress large small. holding pressure pressure increase make separation 子间隙变 small, active scope/range decrease small, melt shrink small, density large, separation function force increase, can improvement product sink marks and internal quality, 但会导致 internal stress large, therefore, in ensure product appearance quality front lower amount selection relatively low holding pressure pressure. generally lower, combined holding pressure pressure is injection pressure 60~80%.

holding pressure time setting is according to gate cooling formed solid 化, screw again already again for molding product add pressure is time. holding pressure time setting injection shot time and pressure is 基准, rear 渐渐延 long time molding product weight, molding product weight again is is need setting holding pressure time.

5, mold temperature degree

mold temperature degree control for most made parts 充填程 degree, appearance, residual stress is non important. in molding flame retardant PC/ABS时 use mold temperature machine control mold temperature degree, mold temperature is 50-80℃. relatively high mold temperature degree, 往往会 generate good flow, relatively high weld lines strong/high degree, relatively small product internal stress, molding cycle long. mold temperature degree ratio low, 就会导致 high internal stress loss bad made parts most property can. made parts surface and ring cycle 而言, mold temperature degree is temperature degree scope/range in value 时, can to relatively good 结果.

6, cooling time

cooling time setting is product solid mold opening rear generate deformation, can setting long 一点, rear according to product and cooling different slow slow decrease/reduce, product deformation most less cooling time is most cooling time. can 按公式估算: （式 in δ is need cooling products thick degree, mono is mm, α is plastics hot 传导系数. ）

四, summary

总之, flame retardant PC/ABS most important processing precautions has 两点:

1, must for material 进行充 separation drying, easy formed material hydrolysis;

2, control material molding temperature degree and in high temperature 时 滞留 time, easy formed material thermal degradation. its process parameters 彼此协调, according to product and mold structure 差异, comprehensive setting, can to quality stability, appearance more good, property can excellent product