Shanghai Daoqin Plastics Co., Ltd.

 一, 缺口敏感 property

causes:

PBT separation in ring and ester formed large system, decrease small separation 子链 柔曲 property, make separation rigid property increase, and property ester 基, 羰基 存 in make separation function force increase large, separation rigid property 进一步 reinforcement, from tough property very 差.

solution methods:

a) polymerization modified

polymerization modified is through copolymer, grafting, 嵌段, crosslinked and other in polymerization process in in PBT separation in new flexible 链段, make its tool has good tough property.

b) blending modified

blending modified is will modifier or high impact strong/high degree material and PBT blending or composite/compounding, make its as is dispersion versus distribution in PBT基体 in, utilizing separation separation versus property or interface function, improve/increase PBT impact property can. in PBT in add reaction property increase agent POE-g-GMA, through GMA and PBT 端羧基 原位 increase reaction, add strong/high interface function force, to toughened 效果.

in electronics electrical appliances, automotive electronics industrial field/area, parts more thin is trend, this requirements material need more high flow property, can can can small versus 应浇注 device filling pressure or clamping force achieve type filling.

图1: thin electronics parts

improvement methods:

1. injection molding process upper can through improves injection molding temperature degree and injection molding pressure improve/increase material injection molding flow property, meanwhile can through improve/increase mold temperature and injection speed degree decrease material fast cold 凝.

its outer, mold need 开设良 good gas . also can 适当 开 wide 进胶口, this 样 话一方面 can improvement material flow property, 另一方面 also can improve/increase injection molding process adjustment upper 限.

但现实 production in can can to issues is, temperature degree pressure upper rear, made parts is can 注满, is is thin made parts, high temperature high pressure process conditions lower, product easy 出现脆裂, to can can need 材 material improvement 适应 .

2. material 方面: is improvement PBT hard property, generally is 考虑 add 进一定 amount toughening agent . toughening agent add also 会导致 flow property decline. R&D engineering 师凭借 its more year PBT plastics modified experience, already 掌握 for flow property effect/influence less toughened formulation , can large large improvement thin 壁PBT product property issues.

in addition add 入如CBT and other tool has structure type low separation polyester, its and PBT tool has very good versus property, therefore less add amount,就 can large degree improve/increase resin flow property,而几乎不 effect/influence force property can.

causes:

warpage is material non-uniform shrinkage 结果. material in separation orientation and crystallization, injection molding using/adopting 不恰当 process conditions , mold design gate and 位置不 for , products design thick thick thin 不匀 and other 都会造 formed products warpage.

PBT/GF composite/compounding material warpage main/primary is glass fiber (GF) in flow direction upper toward made resin shrinkage, PBT in glass fiber (GF) 周围 诱导 crystallization also strong/high this type of 效果, make products toward （ flow direction ） shrinkage small toward （ and flow direction direction ）, this type of non-uniform shrinkage 便导致 PBT/GF composite/compounding material warpage.

图2: filling material and filling material shrinkage 不均

solution methods:

1. injection molding process: 因 is this is add glass fiber (GF) rear separation orientation 差异导致 warpage, therefore injection molding process upper need 适当 improve/increase mold temperature degree and injection molding cycle improvement.

2.材 material 方面: if process upper can let warpage to improvement, can for material formulation optimization. its 一 add material , utilizing material filler for property decrease light glass fiber (GF) orientation formed toward property. its 二, add 入如AS and other non material , decrease/reduce crystallization formed non-uniform shrinkage. has formed stability PBT resistant warpage product solution/scheme, meanwhile according to requirements for property product solution/scheme.

causes:

fiber exposure generate causes comparison complex, simple 说, main/primary has below/following several 方面

（a）PBT and glass fiber (GF) versus property very 差, 导致二者无 method has adhesion in 一起;

（b）PBT and glass fiber (GF) viscosity very large , 导致二者 in flow process in formed separation trend, separation function large bonding force 时就会发生脱离, glass fiber (GF) toward outer outer 漏;

（c）剪切 force in , 既会导致 local viscosity has 差异, also bad glass fiber (GF) surface interface melt viscosity small, interface loss, glass fiber to adhesion force small,当 viscosity small to 一定程 degree 时, glass fiber 便会摆脱PBT resin 基体 束缚,逐渐 toward surface 累积而 outer 露.

（d） mold temperature degree effect/influence. due to mold type temperature degree relatively low, quality light cold fast glass fiber by 瞬間冻结,若不 can and by melt separation 包围,就会 outer 露而形 formed “ fiber exposure ”.

图3: glass fiber reinforced PBT surface fiber exposure 图

solution methods:

1. injection molding process: can use relatively high injection molding temperature degree and mold temperature degree , relatively large injection molding pressure and back pressure , relatively fast injection molding speed degree and relatively low screw speed , can 一定程 degree improvement fiber exposure issues.

2.材 material 方面: in PBT modified can add compatibilizer, dispersant and lubricant and other improvement fiber exposure issues. can use PBT short type product, short material versus for/regarding long will large improvement product fiber exposure issues.

causes:

模垢 generate is 由材 material small separation content high or material heat stabilized property relatively 差引起. PBT due to its poly material and small separation 子残留 rate usually in 1%～3%, versus for and other material easy generate 模垢. in glass fiber (GF) rear, more add obvious. this will in processing process in, need 定时清理 mold, formed production efficiency low lower.

图4: injection molding machine mold phenomenon

solution methods:

1) decrease/reduce small separation additives add amount (如 lubricant, coupling agent and other), amount selection polymer/macromolecule additives;

2) improvement PBT heat stabilized property, decrease/reduce processing process in thermal degradation generate small separation material;

causes:

effect/influence PBT hydrolysis main/primary factors is 端羧基 concentrated degree . due to PBT含 has ester 键, in high its 玻璃化转变 temperature degree temperature degree lower water in 会发生 ester fracture, hydrolysis formed acid property ring make hydrolysis accelerated reaction, property can decline.

图5: PBT heat resistant hydrolysis 图

solution methods:

1）添 add hydrolysis stabilizer, 如 carbon 化二亚 amine, hydrolysis stabilizer consumption hydrolysis generate 羧基, decrease 缓PBT acid property hydrolysis speed degree, improve/increase PBT resin resistant hydrolysis property.

2） through add 封闭PBT端羧基 methods, reduce 端羧基 concentrated degree , improve/increase PBT resistant hydrolysis property, add belt/tape ring oxygen can additives (如SAG series, types styrene - acrylonitrile -GMA random copolymer), through can 团GMA and PBT端羧基 reaction 封端, from improve/increase PBT resistant hydrolysis property.