Common faults and solutions of low-density polyethylene (LDPE) blown film

Common faults and solutions of low-density polyethylene (LDPE) blown film

The film is just too sticky and therefore the gap is the poor cause of the issue:

① The rosin material model is wrong, it's not blown film grade low-density polythene resin particles, that doesn't contain open The content of mouth or mouth agent is just too low;

② The temperature of the liquified rosin is just too high and therefore the fluidness is too large;

③ The expanded magnitude relation is just too large, leading to a poor gap in the film;

④ The cooling rate is just too slow, the film is insufficiently cooled, and mutual adhesion happens beneath the pressure of the traction roller;

⑤ Towing speed is just too fast.

Solution:

① Replace rosin raw materials, or add a particular quantity of anti-blocking agent to the bucket;

② befittingly scale back the extrusion temperature and therefore the temperature of the resin;

③ befittingly scale back the inflation ratio;

④ Increase the air volume, improve the cooling effect, and speed up the film cooling speed;

⑤ befittingly scale back the traction speed.

Poor film transparency cause of the issue:

① Extrusion temperature is low, rosin plasticization is poor, leading to poor transparency of the film when blow molding;

② The inflation magnitude relation is just too small;

③ Poor cooling effect, therefore touching the transparency of the film;

④ The wetness content within the rosin stuff is just too large;

⑤ The actuation speed is too quick and therefore the film cooling is insufficient.

Solution: ① Increase the extrusion temperature befittingly in order that the rosin is plasticized uniformly;

② Properly increase the inflation ratio;

③ Increase the air volume and improve the cooling effect;

④ Dry the raw materials;

⑤ befittingly scale back the traction speed.

Wrinkles within the film cause of the issue:

① Uneven film thickness;

② light cooling effect;

③ overlarge blow-up magnitude relation can cause the film bubble to be unstable, swing back and forth from aspect to side, and crease easily;

④ The angle of the fabric splint is just too large, and therefore the film bubble is press during a short distance, that the film is additionally vulnerable to wrinkles. Folding

⑤ The pressure on each side of the traction roller is inconsistent, one side is high and therefore the difference is low;

⑥ The axes of the guide rollers aren't parallel, which affects the soundness and flatness of the film, leading to wrinkles. fold.

Solution:

① change the thickness of the film to confirm uniform thickness;

② Improve the cooling result and make sure that the film is absolutely cooled;

③ befittingly scale back the inflation ratio;

④ scale back the angle of the chevron splint appropriately;

⑤ change the pressure of the traction roller to confirm uniform force on the film;

⑥ Check the axis of every guide shaft and build them parallel to every other.

The film has misty water lines cause of the issue:

① Extrusion temperature is low, rosin plasticization is poor;

② The rosin is damp and therefore the wetness content is just too high.

Solution:

① change the temperature setting of the extruder and increase the extrusion temperature appropriately.

② Drying the rosin raw materials, usually needs that the water content of the resin shouldn't exceed 0.3%.

Uneven film thickness cause of the issue:

① The uniformity of the die gap directly affects the uniformity of the film thickness. If the die gap isn't uniform, The gap in some components is larger, and therefore the gap in some parts is smaller, leading to additional or less extrusion volume. Therefore, The thickness of the shaped film is additionally inconsistent, some components are thin, some parts are thick;

② The temperature distribution of the die mouth is uneven, with high and low temperatures, in order that the thickness of the film when blow molding is uneven;

③ The air offer volume round the cooling air ring is inconsistent, leading to an uneven cooling effect, that makes the film The thickness is uneven;

④ The inflation magnitude relation and traction ratio are inappropriate, creating the thickness of the film bubble troublesome to control;

⑤ The traction speed isn't constant and changes constantly, that in fact can have an effect on the thickness of the film.

Solution:

① change the gap between the die porta of the machine head to confirm uniformity everywhere;

② change the temperature of the die mouth of the machine head to create the temperature of the die mouth half uniform;

③ change the cooling device to confirm uniform air output from the air outlet;

④ change the inflation magnitude relation and traction ratio;

⑤ Check the mechanical transmission to stay the traction speed constant.

The thickness of the film is just too thick cause of the issue:

① The die gap and extrusion volume are too large, that the film thickness is just too thick;

② The air volume of the cooling air ring is just too large, and therefore the film cooling is too fast;

③ Towing speed is just too slow.

Solution:

① change the die gap;

② befittingly scale back the air volume of the air ring to additional inflate the film, thereby creating its thickness thinner;

③ Properly increase the traction speed.

The thickness of the film is just too skinny cause of the issue:

① The die gap is just too little and therefore the resistance is too large, that the film thickness is too thin;

② The air volume of the cooling air ring is just too small, and therefore the film cooling is too slow; ③ The actuation speed is just too fast, the film is stretched too much, and therefore the thickness becomes thinner.

Solution:

① change the die gap;

② Properly increase the air volume of the air ring to hurry up the cooling of the film;

③ befittingly scale back the traction speed.

Poor heat sealability of the film cause of the issue:

① If the saturation point is just too low, the compound molecules are going to be oriented, in order that the performance of the film is near to that of the oriented film, inflicting Reduction of warmth waterproofing performance;

② If the inflation magnitude relation and traction ratio are inappropriate (too large), the film is stretched orientated, which affects the film’s performance Heat waterproofing performance. Solution:

① change the dimensions of the air volume within the air ring to create the saturation point a bit higher, as way as attainable beneath the temperature of the plastic Inflation and traction to scale back molecular stretch orientation caused by inflation and traction;

② The inflation magnitude relation and traction ratio ought to be befittingly smaller. If the inflation ratio is just too large, and therefore the traction speed is too quick and skinny Excessive stretching of the film within the thwartwise and longitudinal directions can cause the film’s performance to tend to be biaxially stretched. the warmth waterproofing of the film Sex can deteriorate.

Poor longitudinal durability of the film cause of the issue:

① If the temperature of the liquified rosin is just too high, the longitudinal durability of the film can decrease;

② The traction speed is slow, and therefore the longitudinal direction of the film isn't enough, which makes the longitudinal durability worse;

③ The blow-up magnitude relation is just too massive and doesn't match the traction ratio, which will increase the orientation and durability of the film within the thwartwise direction. The longitudinal durability can become worse;

④ The cooling rate of the film is just too fast.

Solution:

① befittingly lower the temperature of the liquified resin;

② Properly increase the traction speed;

③ change the inflation magnitude relation to create it compatible with the traction ratio;

④ scale backs the cooling rate appropriately.

Poor thwartwise durability of the film cause of the issue:

① The traction speed is just too fast, that is too completely different from the inflation ratio, which can cause the longitudinal fiber to occur, and therefore the thwartwise strength will amendment difference;

② The cooling speed of the cooling air ring is just too slow.

Solution:

① befittingly scale back the traction speed to match the inflation ratio;

② Increase the air volume of the air ring to cool down the inflated film quickly, avoiding the warm temperature It is stretched and oriented during a high elastic state of temperature.

Bubble instability cause of the issue:

① Extrusion temperature is just too high, the fluidness of the liquified rosin is too large, the viscousness is too small, and it's straightforward to supply fluctuations;

② The extrusion temperature is just too low and therefore the output is small;

③ The air volume of the cooling air ring is unstable, and therefore the film bubble isn't uniformly cooled;

④ Interference and influence by sturdy external air currents.

Solution:

① change the extrusion temperature;

② change the extrusion temperature;

③ Check the cooling air ring to confirm that the air offer around it's even and consistent;

④ forestall and scale back the interference of external airflow.

The surface of the film is the rough and uneven cause of the issue:

① Extrusion temperature is just too low, rosin plasticization is poor;

② Extrusion speed is just too fast.

Solution:

① change the temperature setting of extrusion, and befittingly increase the extrusion temperature to confirm sensible rosin plasticization;

② befittingly scale back the extrusion speed.

The film has a peculiar smell cause of the issue:

① The rosin stuff itself has a peculiar smell;

② The extrusion temperature of the liquified rosin is just too high, which causes the resin to decompose and turn out peculiar smell;

③ light cooling of the film bubble, and therefore the hot air within the film bubble isn't exhausted cleanly.

Solution:

① Replace rosin raw materials;

② change the extrusion temperature;

③ Improve the cooling potency of the cooling air ring, in order that the film bubbles are absolutely cooled.

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