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PPS injection molding processing process and application
Date: 2019-11-17 10:00
Views: 2694
Source: Internet
polyphenylene sulfide (PPS) 英文名称Poly phenylene sulfide, 简称PPS, is types new type engineering plastics , in USA 于1973 year 才开始 industrial production. year development very fast, already formed is 继 nylon （PA）, polycarbonate (PC) （PC）, polyoxymethylene (POM) （POM）, thermoplastic property polyester （PET and PBT） and polyphenylene oxide (PPO) （PPO）之 rear large engineering plastics and large specialty engineering plastics.
product separation is type: type is type thermoplastic property polymer, viscosity relatively high. type is hot solid property polymer, solid front tool has property separation structure, solid rear add hot separation soft to 一定程 degree. lower main/primary introduction thermoplastic property PPS.
PPS is separation 子主链 upper tool has 苯硫基 high poly material, due to its structure is ring and 硫交替连接, separation tool has very large rigid property and property, 因而PPS is crystallization property polymer, tool has very more excellent property can, heat resistant property, rigid property, flame retardant property and electrical insulation property. 硫原子 upper for electronics make PPS and glass fiber, machine filler and metal tool has good hydrophilic and property, easy made formed various reinforcement composite/compounding material and alloy material.
一, PPS property can
1, material force property can
PPS is types white, crystallization degree high polymer, density is 1.34. its force property can excellent 良, tensile strength and flexural strength excellent 于PA, PC, PBT and other, tool has high rigid property and resistant creep property, its property relatively large, notched impact strength relatively low, low 于PA, PC, PBT high 于POM. add glass fiber reinforcement rear its force property can more excellent. PPS inert property material 质, 无毒.
2, thermal properties
due to PPS is crystallization property polymer, most high crystallization degree can 达65%, its crystallization temperature degree is 127℃, melting point is 286℃, heat deflection temperature (HDT) 260℃, in gas in 430-460℃ above separation understanding, heat stabilized property ultra- 出PA, PBT, POM and other engineering plastics, long use temperature degree in thermoplastic property plastics most high, can 达220-240℃. PPS also is tool has good hot property and flame retardant property, its oxygen index (LOI) and PVC versus 当, can 达47%, add flame retardant, PPS can to UL 94-V0 grade water 平.
3, electrical property can
PPS separation structure for 称, property, water property low, its electrical insulation property separation excellent 良, and other engineering plastics versus ratio, its dielectric constant small, resistant electrical property versus hot solid property plastics, in high temperature, high wet, frequency and other conditions lower, PPS also can maintain excellent electrical insulation property. add conductive filler, can made conductive property PPS composite/compounding material, used for anti-static and EMI shielding.
4, chemical resistance
due to PPS tool has relatively high crystallization degree, its tool has excellent chemical resistant product property, in 200℃ below/following solvent 于任何 has machine solvent agent, remove strong/high oxidation property acid outer, can 经受各 type acid, alkali, salt 侵蚀, in high temperature lower various chemical product long 期浸泡 rear, also maintain relatively high strong/high degree, 仅次于 PTFE. PPS also tool has good weather resistance and resistant property.
5, processing properties
1）吸 water property
PPS water property relatively low, has 0.02%.
2） flow property
PPS flow property relatively good, can processing thin products, its flow property according to PPS product types, specifications different, property PPS ratio crosslinked PPS flow property high, temperature degree rise high, material material flow property increase, temperature degree high or material material in machine inner time long, material material 会发生部 separation crosslinked, flow reduce.
3） crystallization property
PPS is crystallization property polymer, its crystallization degree molding cooling temperature degree and speed rate 而变, cooling speed degree fast, its crystallization degree low. crystallization degree large small also for its strong/high degree, heat resistant property, weather resistance, dimensional stability has relatively large effect/influence. crystallization degree increase, products hot temperature degree improve/increase, rigid property, surface light degree, surface hard shrinkage rate and other increase, dimensional stability increase.
4） heat stabilized property
PPS in high temperature lower time long 会发生部 separation oxidation crosslinked reaction, material material flow property reduce, color deep, effect/influence products quality and property can. in addition, PPS for metal has relatively strong/high viscous property, need anti material material in machine inner solid 化.
5） shrinkage property
for/regarding crystallization property plastics, in molding processing 时, crystallization degree mold temperature degree increase increase large, crystallization degree increase large, shrinkage rate increase, shrinkage rate mold temperature degree increase large. usually PPS shrinkage rate relatively small, and flow direction shrinkage rate large flow direction 2-4倍. product thick degree, 形状, injection speed degree for shrinkage rate must effect/influence.
6）二次 processing
PPS products can 切削, filament and other machine processing and ultra- 声波 welding, bonding agent and other processing.
二, molding equipment and mold
1, injection molding machine selection
1） clamping force
PPS flow property and ABS, POM versus 近, in clamping force 时, need flow property this factors, selection material flow features 系 K value, can 按第四组 and ABS, POM and other to same.
2） injection amount
according to product weight selection combined injection amount, selection injection amount ultra- 出 more injection molding machine, 以免胶 material in machine inner time long 而发生 oxidation crosslinked reaction solid 化, product color, effect/influence product property can and quality.
3） screw, machine 筒
according to PPS 特征, PPS没 has property, therefore, for/regarding generally PPS material, can using/adopting screw, due to processing temperature degree high has crystallization 体熔化吸 hot, therefore machine add hot device rate must 足够. in more 数情况 lower, PPS都 add glass fiber reinforcement its various property can, this material for machine and screw abrasion loss very large, must using/adopting wear resistant machine screw, hard screw or di metal screw, machine 筒.
4）射嘴
using/adopting 开放式射嘴, inner 径φ3-6mm, add hot device most good is can mono control, this can make molding processing more 方便. has products requirements anti 止流涎, can use 自锁射嘴, 但清理 comparison difficult.
2, product type and mold design
1） product type
PPS crystallization property polymer, product and thick 变化 部位会引起应 force in, 导致应 force cracking, dimensions 变化, strong/high degree decline and other issues 出现, product design product 转角应 is 圆弧 渡, amount thick thin 不均, generally lower products thick degree need ultra- 出7-10mm.
combined add strong/high design can increase products rigid property, anti products warpage, remove residual stress, high flow property, increase strip/profile ratio increase strip/profile high degree and thick degree more good, usually strip/profile is products thick degree semi 并圆角 渡, strip/profile demolding degree is 2-3°.
2） mold material
PPS processing temperature degree relatively high, material temperature degree is 290-330℃, mold temperature degree is 130-180℃, meanwhile PPS in large more 数情况 lower glass fiber reinforcement, inner relatively a large amount of glass fiber, abrasion loss issues must 考虑, mold material 应以140-150℃ is 基准, selection combined alloy material, 如SK, SKD, SKH and other, hardness is HRC60-65, surface electroplating.
3） runner
runner 形状以圆形, is 宜, runner degree is 2-3°, in runner 末端设置 cold material 井.
4） gate
gate can using/adopting type, type, type, type, type and other, using/adopting type gate, is PPS products hardness large, shrinkage rate small. gate 应设置 in products most thick 部位, gate 直径不 small 于0.6mm, for/regarding reinforcement PPS, crystallization orientation strong/high degree and shrinkage rate direction 各异, in design gate and 位置时, must 考虑胶 material flow direction dimensions and strong/high degree 变化, and combined 纹引起 strong/high degree decline, make combined 纹出现 in has negative or negative relatively small and obvious 部位.
5） demolding
is ensure products surface light 洁平整 degree and easy demolding, mold type 腔, runner and other 部位应 has relatively high light degree and demolding degree, demolding degree generally is 1-3°. demolding 顶针 直径, amount, design very important, according to products 形状而定, make ejection force and ejection 平稳, 否则, make products generate local residual stress, from 而引起 products cracks and dimensions degree and other issues.
6）排 gas
PPS products inner has bubbles make its property can obvious decline, due to gas defect 而引起原烧焦, color and surface coarse 糙, effect/influence products appearance and quality, mold must combined 理 开设排 gas or gas 孔, can utilizing separation type and demolding 顶针间隙 排 gas.
7） mold temperature 控
due to PPS molding processing, requirements mold temperature degree in 130-180℃, this temperature degree generally need add hot, mold temperature degree property and uniform property effect/influence to product property can and dimensions degree; according to mold large small, products 形状, production amount and temperature equipment and other factors, can selection electrical hot and ring add hot temperature 控, electrical hot temperature 控方便, 经济, temperature rise fast, temperature degree uniform property and degree relatively 差, mold temperature machine ring add hot temperature temperature degree uniform property and degree relatively high, for property can and dimensions degree requirements relatively high product can selection this type of methods. is ensure mold temperature degree uniform property and anti dispersion hot, can in mold and mold and injection molding machine sheet/plate between add 装石棉 sheet/plate thermal insulation.
三, molding process
1, Raw Materials drying
因 is PPS吸 water property small, therefore processing front can drying. if raw materials 开放式放 in temperature degree high, wet degree large ring lower time relatively long, drying, drying temperature degree is 150-160℃, time 2-3H.
2, molding temperature degree
PPS molding temperature degree relatively high, machine temperature degree in 280-360℃ between, in ensure 顺利充模 and products quality front lower, machine temperature degree amount need high, 以免引起胶 material in machine inner oxidation crosslinked solid 化. temperature degree need mono control, maintain material good flow property also 不堵塞, 不流涎 is 宜.
3, injection pressure
injection pressure in 50-200MPa between, is ensure products force property can and dimensions degree, use relatively high injection force is 佳, especially is complex, thin parts more 应如此.
4, injection speed degree
injection speed degree fast, products surface light degree high, strong/high degree relatively high, high injection speed degree make product warpage, and other phenomenon, generally using/adopting in and other injection speed degree.
5, screw speed
screw speed can in 50-200rpm between, high speed molding can using/adopting relatively high speed, this material 因剪切 speed rate large temperature rise large, must will machine temperature degree low.
6, holding pressure pressure
is anti internal stress generate, pressure pressure amount low, meet/satisfy shrink can, products 不出现凹陷 is 准.
7, back pressure
一定 back pressure has 利于胶 material gas and mixed combined, to quality relatively stability products, generally back pressure in 0.5-1.5MPa between, for/regarding drying good material, back pressure can large.
8, mold temperature degree
PPS is crystallization property polymer, mold temperature degree effect/influence products crystallization degree, from to different property can and dimensions degree, mold temperature degree different crystallization very large, 如94℃时 crystallization is 8%, 而150℃时则 is 48%. mold mold high, to products crystallization degree high, its force property can relatively good, has shrinkage large, 凹陷, warpage, resistant impact strong/high degree and other issues, mold temperature degree low, products crystallization degree low, shrinkage small, dimensions again property good （ products dimensions and mold dimensions made degree ）, resistant impact strong/high degree increase large, ultra- 声波 welding property improve/increase, force property can relatively 差. therefore, need according to product requirements molding mold temperature degree.
9, molding cycle
due to PPS is crystallization property polymer, is to good force property can, 需采取 relatively high mold temperature degree, relatively long cooling time, improve/increase crystallization degree, for/regarding thick products, injection time, holding pressure time, cooling time long thin products. is anti cooling shrinkage and internal stress generate, for complex parts, thin product, need 适当延 long holding pressure time.
10, products rear 处理
is improve/increase products property can, remove internal stress and maintain products property can and dimensional stability, can will products 放入烘箱 inner 进行退火处理, conditions usually is 200-240℃, 2—4H, specific according to products thick degree and applications 而定, thick products time long, 退火处理 make products again crystallization from crystallization degree improve/increase, its property can 也随之而 improve/increase, 但也导致 again shrinkage make products dimensions 变化, mold design need this factors.
11, recycled material use
recycled material can and new material mixed combined use, its ratio/proportion products property can requirements 而定, recycled material ratio/proportion large, products property can decline, generally need ultra- 30%, 以免造 formed product property can and quality obvious decline.
12, machine 处理
due to PPS for metal has relatively strong/high viscous property, processing formed rear, in machine front must machine inner, screw upper viscous 附 PPS material 清洗出, 否则胶 material cooling rear solid viscous in screw upper, effect/influence lower or its it material production, usually can using/adopting high density polyethylene (PE) （HDPE） 清洗; is shrink short time, can use glass fiber strong/high PC material, again use HDPE material 进行清洗, this 样清洗效果 relatively good use relatively high. production process in need in molding time, must will machine inner material full 部排出, will machine temperature degree reduce 至270℃ below/following, is material in high temperature conditions lower long time hot separation understanding, 并放出毒 gas 体, therefore production 场 必 must attention/notes 通风.
四, Common defect and solution methods
1, filling 不足
causes:
1） injection pressure 不足; 2） injection speed degree slow; 3）熔 material temperature degree low; 4）排 gas defect; 5） gate small; 6） 胶圈 abrasion loss.
solution methods:
1） improve/increase injection pressure ; 2） improve/increase injection speed degree; 3） improve/increase machine temperature degree ; 4） in 未填满 部位 add gas 孔 ; 5） expand large gate dimensions or shrink short gate runner 距离 ; 6）检查 胶圈 abrasion loss degree, more 换.
2, surface gloss
causes:
1） products density 不足; 2） filling speed degree slow; 3） mold temperature degree low; 4）排 gas defect.
solution methods:
1） increase amount, improve/increase injection pressure; 2） improve/increase machine temperature degree, improve/increase injection speed degree; 3） improve/increase mold temperature degree; 4）充 separation gas.
3, warpage
causes:
1） products cooling non-uniform; 2） products thick non-uniform; 3） filling degree; 4） injection speed degree fast.
solution methods:
1） adjustment mold temperature degree control, make its cooling uniform; 2） product design amount make its thick uniform; 3） reduce injection pressure and holding pressure pressure ; 4） reduce injection speed degree.
4, shrinkage, 凹陷
causes:
1） products density 不足 ; 2）熔 material has gas 体; 3） products thick thick ; 4） hot shrinkage large.
solution methods:
1） increase amount, improve/increase injection pressure, long injection time; 2）充 separation drying material; 3） products thick degree need ultra- 7-10mm; 4） reduce machine temperature degree and mold temperature degree.
5, internal cracks
causes:
1） products cooling fast 2） residual stress
solution methods:
1） improve/increase mold temperature degree, products rear hot water or 放入烘箱 in slow cooling ; 2） reduce injection speed degree, improve/increase mold temperature degree.
6, 烧焦
causes:
1）排 gas defect; 2）熔 material temperature degree high.
solution methods:
1） increase gas 孔; 2） reduce machine temperature degree, injection speed degree; 3） add large gate .
7, demolding difficult, ejection 破裂
causes:
1） mold demolding degree 不足, surface light degree 不足; 2） demolding 顶针 位置不当 or small
solution methods:
1） add large demolding degree, mold surface light; 2） increase 顶针数 amount or add large 顶针直径; 3）延 long cooling time, reduce machine temperature degree, mold temperature degree
五, application
1, electronics electrical appliances and home appliances
utilizing its high temperature resistance, electrical insulation property, used for parts, pressure device, electrical appliances, electrical 饭煲, micro 波炉, and other parts.
2, machine and precision parts
utilizing its good processing property and high temperature resistance, corrosion resistant and other 特征, used for versus machine, speed table/sheet, table/sheet, machine, electrical and other parts.
3, automotive
utilizing its high temperature resistance, oil resistant, corrosion resistant, strong/high degree high and other features, used for machine cover/cap, gas plant/unit, dispersion hot plant/unit, device and other parts.
4, chemical industry
utilizing its heat resistant, corrosion resistant features, used for 泵, tube/pipe, 阀, container and other.
