Shanghai Daoqin Plastics Co., Ltd.

large more thermoplastic property plastics 都 can use blow molding method production blow molding film, blow molding film is will plastics 挤 formed thin tube/pipe, rear hot use pressure shrink gas will plastics 吹胀, again cooling type rear to film products, this type of film property can 处于定 toward film 同流延 film between: strong/high degree ratio film good, hot property ratio film 差. blow molding method production film product types has very more, ratio low density polyethylene (PE) (LDPE), property polyethylene (PE) （LLDPE), polypropylene (PP) (PP), high density polyethylene (PE) (HDPE), nylon (PA), ethylene acid ethylene copolymer (EVA) and other, this 里我们就 for commonly used LDPE, LLDPE film blow molding production process and its Common fault/failure simple introduction.  

polyethylene (PE) blow molding film material selection
1. selection raw materials is use film grade polyethylene (PE) resin pellets, has amount slip agent, ensure film property.
2. resin pellets melt flow index (MI)不 can large, melt flow index (MI)太 large, melt resin viscosity small, processing scope/range narrow, processing conditions difficult control, resin formed film property 差, easy processing formed film; in addition, melt flow index (MI)太 large, polymer versus for molecular weight distribution narrow, film strong/high degree relatively 差. therefore, selection melt flow index (MI) relatively small, versus for molecular weight distribution relatively wide resin raw materials, this can meet/satisfy film property can requirements, also can ensure resin processing features. blow molding polyethylene (PE) film generally selection melt flow index (MI) in 2～6g/10min scope/range between polyethylene (PE) raw materials.

blow molding process control key points

blow molding film process process/workflow large lower: material upper material material material extrusion →吹胀牵引→风 ring cooling →人字夹 sheet/plate →牵引辊牵引→ electrical 晕处理→ film 收卷

但 is, value is, blow molding film property can production process parameters has very large 关系, therefore, in film process in, must need add strong/high for process parameters control, specification process as, ensure production 顺利进行, obtain high quality film product. in polyethylene (PE) blow molding film production process in, main/primary is good below/following process parameters control:

1． extrusion machine temperature degree

blow molding LDPE, LLDPE film 时, extrusion temperature degree generally control in 160℃～170℃ between, must ensure machine temperature degree uniform, extrusion temperature degree high, resin easy separation understanding, film 发脆, especially make toward tensile strength significantly decline; temperature degree low, resin defect, can slip 进行膨胀 tensile, film tensile strength relatively low, surface gloss property and transparent degree 差, 甚至出现像木材 year 轮般 花纹以 and 未熔化 晶核(鱼眼).

2．吹胀 ratio

吹胀 ratio is blow molding film production process control key points 之一, is 指吹胀 rear film 泡 直径 and 未吹胀 tube/pipe ring between ratio value. ratio is film toward 膨胀倍数, upper is for film 进行横 toward tensile, tensile for plastics separation generate 一定程 degree orientation function, ratio increase large, from make film toward strong/high degree improve/increase. is, ratio can large, 否则容 easy formed film unstable, film easy 出现皱折. therefore, ratio 应当同牵引 ratio combined 适当才行, generally 说, LDPE, LLDPE film ratio control in 1.5～3.0 is 宜.

3．牵引 ratio

牵引 ratio is film speed degree and tube/pipe ring extrusion speed degree between ratio value. ratio is toward tensile 倍数, make film in direction upper tool has toward function. ratio increase large, toward strong/high degree 也会随之 improve/increase, film thick degree thin, if ratio large, film thick degree difficult control, has can can will film 拉断, formed film phenomenon. film ratio generally control in 4～6 between is 宜.

4.露点

露点 also 称霜线, plastics viscous 流态进入 high elastic separation 界线. in film process in, polyethylene (PE) in from in extrusion 时呈熔 melt 状态, transparent property good. mold opening rear, need through cooling ring for film 泡 吹胀区进行 cooling, cooling gas 以一定 角 degree and speed degree toward rigid from machine extrusion plastics film 泡时, high temperature film and cooling gas versus 接触, film hot amount by cold gas belt/tape 走, its temperature degree obvious decline to polyethylene (PE) viscous temperature degree below/following, from make its cooling solid 化且变 模糊不清. in blow molding film upper can to strip/profile transparent and between separation 界线, this is 露点(or 者称霜线).

in film process in, high low for film property can has effect/influence. if high, 位于吹胀 rear film upper 方, film is in liquid lower 进行, 吹胀仅 make film thin, separation 子不受 to tensile orientation, this 时 吹胀 film property can 接近于流延 film. versus 反, if comparison low, 则吹胀 is in solid lower 进行, plastics high elastic lower, 吹胀就如同横 toward tensile 一样, make separation 子发生 orientation function, from make film property can 接近于定 toward film.

basic property can technology requirements

1． specifications and 偏差

polyethylene (PE) film wide degree, thick degree 应当符 combined requirements, film thin thick uniform, 横, toward thick degree small, 且偏差 distribution comparison uniform.

2. appearance

requirements polyethylene (PE) film 塑化良 good, obvious " water 纹" and "云雾"; film surface 应当平整 light slip, 无皱折 or has a small amount of active 褶; 不允许 has bubbles, and phenomenon; obvious black spots, 杂质, and block; 不允许 has heavy material and filament in.

3． material mechanical properties

due to blow molding rear polyethylene (PE) film used for printing or composite/compounding processing process 时, need to machine force function, therefore, requirements polyethylene (PE) film material mechanical properties excellent 良, main/primary tensile strength, fracture elongation, strong/high degree and other indicators 应当符 combined standards.

4． surface force large small

is make printing ink and composite/compounding use viscous agent in polyethylene (PE) film surface tool has good lubricating wet property and force, requirements polyethylene (PE) film surface force 应当达 to standards, 否则就会 effect/influence printing and composite/compounding production 顺利进行. generally 说, polyethylene (PE) film surface force less 应当达 to 38达因 above, to 40达因 above more 佳.

LDPE, LLDPE blow molding film Common fault/failure and solution methods

1． film viscous, property 差

fault/failure causes:

① resin raw materials Model/Grade for, is film grade polyethylene (PE) resin pellets, its in 不含开口 agent or 者开口 agent content low;

②熔 melt resin temperature degree high, flow property large;

③吹胀 ratio large, formed film property 变差;

④ cooling speed degree slow, film cooling 不足, in 牵引辊 pressure function lower versus adhesion;

⑤牵引 speed degree fast.

solutions:

① more resin raw materials, or toward in add amount agent;

②适当 reduce extrusion temperature degree and resin temperature degree;

③适当 reduce ratio;

④ add large amount, improve/increase cooling 效果, add fast film cooling speed degree;

⑤适当 reduce speed degree.

2． film transparent degree 差

fault/failure causes:

① extrusion temperature degree low, resin defect, formed blow molding rear film transparent property relatively 差;

②吹胀 ratio small;

③ cooling 效果不佳, from effect/influence film transparent degree;

④ resin raw materials in water separation content large;

⑤牵引 speed degree fast, film cooling 不足.

solutions:

①适当 improve/increase extrusion temperature degree, make resin can uniform 塑化;

②适当 improve/increase ratio;

③ add large amount, improve/increase cooling 效果;

④ for raw materials 进行烘 dry 处理;

⑤适当 reduce speed degree.

3. film 出现皱折

fault/failure causes:

① film thick degree non-uniform;

② cooling 效果不够;

③吹胀 ratio large, formed film unstable, left right 回摆动, easy 出现皱折;

④人字夹 sheet/plate large, film in short inner by pressure 扁, therefore film easy 出现皱折;

⑤牵引辊两边 pressure 不一致, high low;

⑥各导 toward between 轴线不平行, effect/influence film stability property and property, from 而出现皱折.

solutions:

① adjustment film thick degree, ensure thick degree uniform 一致;

② improve/increase cooling 效果, ensure film can separation cooling;

③适当 reduce ratio;

④适当 decrease small 人字夹 sheet/plate 夹角;

⑤ adjustment 牵引辊 pressure, ensure film force uniform;

⑥检查各导 toward 轴 轴线, make versus 互平行.

4, film has water 纹

fault/failure causes:

① extrusion temperature degree low, resin defect;

② resin 受潮, water separation content high.

solutions:

① adjustment extrusion machine temperature degree 设置, 并适当 improve/increase extrusion temperature degree.

② will resin raw materials dry, generally requirements resin water amount can ultra- 0.3％.

5. film thick degree non-uniform

fault/failure causes:

①模口间隙 uniform property effect/influence film thick degree uniform property, if 模口间隙 non-uniform, has 部位间隙 large 一, has 部位间隙 small 一, from formed extrusion amount has more has less, therefore, formed film thick degree 也就不一致, has thin, has thick;

②模口 temperature degree distribution non-uniform, has high has low, from make blow molding rear film thin thick 不均;

③ cooling ring 四周 送风 amount 不一致, formed cooling non-uniform, from make film thick degree non-uniform phenomenon;

④吹胀 ratio and ratio combined 适, make film thick degree easy control;

⑤牵引 speed degree 不恒定, 不断 发生变化, this 当然就会 effect/influence to film thick degree.

solutions:

① adjustment machine 头模口间隙, ensure uniform 一致;

② adjustment machine 头模口 temperature degree, make 模口部 separation temperature degree uniform 一致;

③ adjustment cooling plant/unit, ensure 出风口 出风 amount uniform;

④ adjustment ratio and ratio;

⑤检查 machine 械传动 plant/unit, make speed degree maintain 恒定.

6． film thick degree thick

fault/failure causes:

①模口间隙 and extrusion amount large, therefore film thick degree thick;

② cooling ring amount large, film cooling fast;

③牵引 speed degree slow.

solutions:

① adjustment 模口间隙;

②适当 decrease small ring amount, make film 进一步吹胀, from make its thick degree thin 一;

③适当 improve/increase speed degree.

7. film thick degree thin

fault/failure causes:

①模口间隙偏 small, retardant force large, therefore film thick degree thin;

② cooling ring amount small, film cooling slow;

③牵引 speed degree fast, film tensile degree, from make thick degree thin.

solutions:

① adjustment 模口间隙;

②适当 increase large ring amount, add fast film cooling;

③适当 reduce speed degree.

8． film hot property 差

fault/failure causes:

①露点太 low, polymer separation 子发生定 toward, from make film property can 接近定 toward film, formed hot property can reduce;

②吹胀 ratio and ratio 不适当(large), film tensile orientation, from effect/influence film hot property can.

solutions:

① adjustment ring in amount large small, make high 一点, can can in plastics melting point lower 进行吹胀 and 牵引, decrease/reduce 因吹胀 and 牵引导致 separation tensile orientation;

②吹胀 ratio and ratio 应适当 small 一点, if ratio large, 且牵引 speed degree fast, film toward and toward tensile degree, that 么, make film property can di toward tensile, film hot property 就会变差.

9． film toward tensile strength 差

fault/failure causes:

①熔 melt resin temperature degree high, make film toward tensile strength decline;

②牵引 speed degree relatively slow, film toward toward function 不够, from make toward tensile strength 变差;

③吹胀 ratio large, 同牵引 ratio 不匹配, make film toward toward function and tensile strength improve/increase, toward tensile strength 就会变差;

④ film cooling speed degree fast.

solutions:

①适当 reduce melt resin temperature degree;

②适当 improve/increase speed degree;

③ adjustment ratio, make and ratio versus 适应;

④适当 reduce cooling speed degree.

10. film toward tensile strength 差

fault/failure causes:

①牵引 speed degree fast, 同吹胀 ratio versus large, make toward generate fiber 化, toward strong/high degree 就变差;

② cooling ring cooling speed degree slow.

solutions:

①适当 reduce speed degree, make and ratio versus combined;

② add large ring amount, make film fast speed cooling, in relatively high

temperature degree high elastic lower by tensile orientation.

11. film unstable

fault/failure causes:

① extrusion temperature degree high, melt resin flow property large, viscosity small, easy generate 波动;

② extrusion temperature degree low, material amount less;

③ cooling ring amount unstable, film cooling non-uniform;

④受 to outer relatively strong/high gas dry and effect/influence.

solutions:

① adjustment extrusion temperature degree;

② adjustment extrusion temperature degree;

③检查 cooling ring, ensure 四周 送风 amount uniform 一致;

④ retardant and decrease small outer gas dry 扰.

12, film surface coarse 糙, 凹凸不平

fault/failure causes:

① extrusion temperature degree low, resin defect;

② extrusion speed degree fast.

solutions:

① adjustment extrusion temperature degree 设置, 并适当 improve/increase extrusion temperature degree, ensure resin 塑化良 good;

②适当 reduce extrusion speed degree.

13． film has 异味

fault/failure causes:

① resin raw materials has 异味;

②熔 melt resin extrusion temperature degree high, formed resin separation understanding, from generate 异味;

③ film cooling 不足, film inner hot gas has troubleshooting dry 净.

solutions:

① more resin raw materials;

② adjustment extrusion temperature degree;

③ improve/increase cooling ring cooling efficiency, make film separation cooling.

stability property resistant chemical property 佳PPA GV-4H_nat_E Switzerland EMS