Shanghai Daoqin Plastics Co., Ltd.

         polyphenylene sulfide (PPS), full is poly 次苯基硫 ether, 英文名称polyphenyleneSulfide(简称PPS), is separation 子主链 upper belt/tape has 苯硫基 thermoplastic property engineering plastics.

         polyphenylene sulfide (PPS) heat resistant property excellent 良, long use temperature degree in 200℃; chemical resistant product property good, tool has PTFE excellent chemical property can; also tool has rigid property, good and various filler and its it polymer/macromolecule material blending property. currently, it is high temperature resistance engineering plastics in price most low also can generally thermoplastic property plastics processing methods molding product types.

         polyphenylene sulfide (PPS) is ring and 硫原子交替排列构 formed type polymer/macromolecule combined material, due to ring rigid property structure soft property ether 键连结起, make its tool has excellent heat resistant property, flame retardant property, resistant property and and its it machine filler good hydrophilic and property. modified polyphenylene sulfide (PPS) resistant strong/high degree, resistant strong/high degree in and other water 平, elongation and impact strong/high degree relatively low.

         therefore, polyphenylene sulfide (PPS) using/adopting glass fiber and its it machine filler reinforcement filling modified, make its in maintain heat resistant property, flame retardant property and resistant property meanwhile, 进一步 improve/increase material mechanical properties.

        现就几 types relatively Common products defect add analysis and discussion.

        一, products resistant temperature low, color, 出现变黑, and black spots

         due to polyphenylene sulfide (PPS) blending property good, tool has good rigid property, through add glass fiber, its rigid property can 进一步 improve/increase. PPS heat resistant property very good, usually injection material temperature degree setting in 280～340℃, production product resistant temperature in 200℃ above long use temperature degree, can is what in production electrical appliances products 时, 经常会出现变 color phenomenon 呢?

         this is is in market competition 激烈, is reduce production cost, has production in low products use recycled material (recycling material), add other material, add flame retardant, filling agent and other mixed material. due to this material product 流驳杂, 而塑化 requirements comparison high, process control comparison difficult, from 而出现 this that issues.

        PPS its melting point (282～285℃)添 add material temperature degree versus large, formed add material 烧伤, gas 化, carbon 化, color color 变黑, has and black spots phenomenon.

        针 for upper phenomenon, from below/following several 方面进行考虑 and solution methods:

        1. raw materials:

         if in production process in has color phenomenon, 就需首先检查 use material is has issues, ratio 如掺杂 its it material and material new material is in quality issues, use recycling material is combined 格, mixed material is formulation method positive and other, troubleshooting rear, again its it causes.

        2. process conditions 方面:

         main/primary 考虑熔 melt temperature degree, generally need reduce material temperature degree, especially is front temperature degree, but also for different material use different temperature degree, nylon blending modified polyphenylene sulfide (PPS); can significantly improve/increase impact strong/high degree. although polyphenylene sulfide (PPS) and nylon 两者 熔 melt temperature degree and hot separation understanding temperature degree versus 差悬殊, hydrophilic and property 不够理想, it in relatively high temperature degree lower can generate separation excellent 良 熔 mixed 效果. temperature degree from material to nozzle separation control, is 260℃, 280℃, 300℃, 310℃.

        PC polycarbonate (PC), PPO polyphenylene oxide (PPO), PTFE poly fluorine dilute, PI polyimide (PI) and other and other blending modified polyphenylene sulfide (PPS) various specifications material, material add hot temperature degree has 差异. 当然, molding temperature degree most 终选定 also need comprehensive products 形状, dimensions, mold structure, products property can requirements and other 方面.

         another, screw speed fast, back pressure high, injection speed rate fast, and nozzle 孔径, 浇道, gate dimensions small and other make melt generate high hot, formed PPS出现 melt phenomenon, but also easy make mold cavity inner gas can and 时排出, formed products local 灼伤而变黑.

        3. use material, as methods 方面:

        若一开 machine 就发现 has black spots, this more semi and material material has 关, must attention/notes as methods methods, machine front material 筒 存 material is PPS时, need use new material in molding temperature degree lower will material 筒清洗3～4次(for injection). if material is material, especially is heat stabilized property material 如PVC, POM and other, this requirements in machine can rise high temperature degree, but also can use PPS清洗 material 筒, can in relatively low temperature degree lower use heat stabilized property good material 如PS polystyrene (PS), PE polyethylene (PE) and other material.

        清洗 dry rear, again material temperature degree rise 至PPS positive processing temperature degree, rear use PPS material 清洗一 lower, can processing. in processing process in, 若需临时 in production, will material temperature degree drop to 280℃ below/following temperature, (因PPS temperature degree is 280℃), time long material material separation understanding color.

        二, made parts surface quality good, light degree 差, glass fiber (GF) outer 露

        出现 above several issues, its main/primary causes is mold temperature degree low, formed made parts surface quality good.

         due to polyphenylene sulfide (PPS) is crystallization property polymer/macromolecule combined material, mold temperature degree for polyphenylene sulfide (PPS) made parts property can has obvious effect/influence.

         made parts 因骤然 cooling 而 不 to separation crystallization, from make its machine strong/high degree, material heat resistant property has decline; mold temperature improve/increase, made parts crystallization property 随之而 improve/increase, rigid property meanwhile improve/increase.

        PPS injection molding parts crystallization 状况受 melt cooling speed rate effect/influence. melt cooling speed degree fast, PPS viscosity large increase 导致链段 active property reduce, heavy 排跳进晶格 极遇变 small, crystallization to made 甚至不 can very good crystallization, crystallization degree small;当 melt cooling speed degree slow and crystallization, crystallization in very large degree upper expand large, mold temperature improve/increase, made parts crystallization property 随之而 improve/increase.

        1. in usually lower, mold temperature degree control in 120℃ above, is what need mold add hot?

        因 is mold temperature degree in 38℃ molding polyphenylene sulfide (PPS) made parts crystallization degree small 于5%, can parts although basic molding, parts internal structure also has to requirements. need improve/increase parts crystallization degree, must rear 处理, in 204℃ lower hot 处理30min, its crystallization degree can improve/increase to 60%, therefore in injection molding process fine in 规定, hot 处理: products requirements in 48 small inner 进行处理.

         will products 放入烘箱 in, its thick degree ultra- products 三倍, in 1 small inner room temperature rise 止200℃, maintain 2 small rear, (零部 parts comparison large 时, time toward rear 延缓)切断 electrical 源随烘箱 cooling room temperature, products. is need mold temperature degree low molding products.

         surface light degree good, formed light for requirements surface light degree high parts, basic can meet/satisfy requirements. (注: requirements parts surface light degree high, mold temperature degree control in 120℃ above.)

        2. mold type surface light degree high, is parts surface light degree high causes 之一

         requirements surface light degree high parts, mold type light, again light 直至达 to use requirements.

        三, made parts cracking and other phenomenon

         this main/primary is due to products internal in internal stress 缘故.

         internal stress, is in has outer force lower, plastics internal due to molding 不当, temperature degree and other causes generate force, its essence is plastics separation high elastic deformation by in products inner formed.

         plastics products internal stress can effect/influence products force property can and use property can, generate warpage, deformation fine small 裂缝: internal stress also make injection molding products in flow direction upper 显示出 relatively high force property can, 而垂直于 flow direction strong/high degree relatively low, make products property can non-uniform, from effect/influence products use. especially is products hot or and solvent agent 接触时 will accelerated cracking.

        PPS products internal stress is orientation force and temperature degree force 引起, has and demolding has 关.

        1. orientation force

         injection products internal large separation orientation rear easy generate internal stress, formed force in.

         in injection molding melt (material)迅 speed cooling, in relatively low temperature degree lower melt viscosity relatively high, orientation separation can separation 松弛, generate internal stress for parts force property can and dimensional stability has effect/influence. therefore melt temperature degree (material temperature degree) for orientation force effect/influence most large, improve/increase melt temperature degree (material temperature degree) for melt viscosity decline, 因而剪切应 force and orientation force reduce.

        ① in high melt temperature degree (material temperature degree) lower orientation force 松弛程 degree relatively large, viscosity reduce 时, injection machine screw to mold type pressure increase large, can can make speed rate improve/increase, orientation force increase large.

        ② holding pressure time long, orientation force increase large: improve/increase injection machine pressure 同样会因剪切应 force and speed rate increase 而引起 orientation force increase large.

        ③ injection molding products thick degree for internal stress has effect/influence, orientation force injection molding products thick degree increase reduce, is thick injection molding parts cooling slow, melt in mold cavity inner cooling, time relatively long, orientation separation has time to random 状态.

        ④ 若 mold temperature degree high, melt cooling slow, can make orientation force decrease/reduce.

        2. temperature degree force

         plastics in injection molding melt temperature degree (material temperature) and mold temperature degree between temperature very large, this make 靠近模壁 熔 material cooling relatively is speed, generate in products inner distribution non-uniform force.

        ① due to PPS specific heat capacity relatively large, thermal conductivity small, products surface ratio inner cooling fast more, products surface formed solid housing/shell retardant internal cooling 时 自由 shrinkage, its 结果引起 products internal generate tensile force, in outer generate pressure shrink force.

        ② thermoplastic property plastics shrinkage generate force large, material in inner pressure function generate force low, holding pressure time short, holding pressure pressure low, can very good decrease small toward force.

        ③ products and dimensions for internal stress has very large effect/influence. products surface and 体积之 ratio large, surface cooling fast, orientation force, temperature degree force large.

        ④ orientation force main/primary generate in products table/sheet inner, therefore, can is orientation force 应该随 products surface for its 体积之 ratio increase increase large.

        ⑤ 若 products thick degree non-uniform or products belt/tape has metal parts easy generate orientation force, therefore parts and gate 都宜设置 in products thick 壁处.

         through above several analysis, due to plastics structure and injection molding process conditions made, need full internal stress is can can, can amount decrease small internal stress or amount make internal stress in products inner distribution uniform.

         its methods is:

        ① injection temperature degree for products internal stress large small effect/influence very large, therefore need improve/increase material temperature degree, ensure material material 塑化良 good, make separation uniform reduce shrinkage rate, decrease small internal stress; improve/increase mold temperature degree, make products cooling slow, 以松弛 orientation separation 子, reduce internal stress.

        ② high holding pressure time long pressure can make plastics separation orientation function large generate relatively large force, make plastics separation has 序排列, products orientation force large, therefore, need amount using/adopting relatively low injection pressure;若 holding pressure time long, inner pressure due to pressure function improve/increase, material generate relatively high pressure 效应, separation orientation degree improve/increase, make products internal stress large, therefore holding pressure time 不宜太 long.

        ③ injection speed rate for injection molding parts internal stress effect/influence ratio temperature degree, pressure and other factors need small more, most good using/adopting speed injection, fast speed 充模, mold cavity rear use low speed, speed injection 一方面充模 process fast, decrease/reduce 熔接痕, 另一方面 low speed holding pressure can decrease/reduce separation orientation.

        ④ design gate 位置, generally gate 位置都宜设置 in products thick 壁处, products need use gate, gate;PPS材 material 不适应潜伏式点 gate. ejection plant/unit design formed large metal ejection; demolding degree need large.

        ⑤ 当 products belt/tape has metal parts 时, parts 需预先 add hot (generally requirements add hot 200℃ left right),以 anti metal material and plastics material 线膨涨系数不一致而 generate internal stress, 渡处需 use 圆弧 渡.

        ⑥ 出模 rear products need in 24 small inner rear 处理, remove internal stress, hot temperature degree is 200℃ left right, temperature time 2～3 small 时. its is make plastics separation in 链段, has active can force, elastic property deformation to 松弛, orientation separation to random 状态.