Brief description of blown film common faults and solutions

The film is too viscous, and the opening is poor. Causes of failure: 1 The type of resin material is not correct, not blown film-grade low-density polyethylene resin particles, in which the content of the opening agent or opening agent is not low; 2 the temperature of the molten resin is too high, the fluidity Too large; 3 blow-up ratio is too large, resulting in poor opening of the film; 4 cooling rate is too slow, the film cooling is insufficient, under the action of the traction roller pressure, mutual adhesion occurs; 5 pulling speed is too fast.
Remedy: 1Replace the resin raw material, or add a certain amount of opening agent to the tube; 2Adjust the extrusion temperature and the temperature of the resin properly; 3Properly reduce the blow-up ratio; 4Increase the air volume, improve the cooling effect, and accelerate the film cooling Speed; 5 properly reduce the traction speed. 2. The reasons for the poor transparency of the film are as follows: 1 The extrusion temperature is low and the resin is poorly plasticized, resulting in poor transparency of the film after blow molding; 2 Insufficient blow-up ratio; 3 Poor cooling effect, which affects the transparency of the film; 4 The moisture content in the resin material is too large; 5 the pulling speed is too fast and the film cooling is insufficient.
Solution: 1 Properly increase the extrusion temperature so that the resin can be uniformly plasticized; 2 Properly increase the blow-up ratio; 3 Increase the air volume and improve the cooling effect; Dry the raw materials; 5 Properly reduce the traction speed.
3 film wrinkle failure causes: 1 film thickness is not uniform; 2 cooling effect is not enough; 3 blow ratio is too large, causing bubble instability, left and right swing back and forth, prone to wrinkles; 4 Herringbone angle included Large, the bubble is flattened in a short distance, so the film is also prone to wrinkling; 5 pressure on both sides of the pulling roller is inconsistent, high side and low side; 6 axis between the guide roller is not parallel, affect the stability of the film and peace Extensibility, resulting in wrinkles. Solution: 1 Adjust the thickness of the film to ensure that the thickness is uniform; 2 Improve the cooling effect to ensure that the film can be fully cooled; 3 Properly reduce the blow-up ratio; 4 Reduce the angle of the herringbone properly; 5 Adjust the pressure of the traction roller, Ensure that the film is evenly loaded; 6 Check the axes of the guide shafts and make them parallel to each other. 4, the film has a mist-like water mark failure causes: 1 extrusion temperature is low, poor resin plasticization; 2 resin moisture, moisture content is too high. Solution: 1 Adjust the temperature setting of the extruder and increase the extrusion temperature appropriately. 2 The drying of resin raw materials generally requires that the moisture content of the resin should not exceed 0.3%. 5. Film thickness non-uniformity Causes of failure: 1 The uniformity of the die gap directly affects the uniformity of the film thickness. If the die gap is not uniform, some parts have large gaps, and some have small gaps, resulting in extrusion. There are more or less, so the thickness of the film formed is also inconsistent, some parts are thin, some parts are thick; 2 die mouth temperature distribution is uneven, there are high and low, so that the thin film thickness after blow molding uneven; 3 The air supply volume around the cooling air ring is inconsistent, resulting in non-uniform cooling effect, resulting in non-uniform thickness of the film; 4 Inappropriate blow-up ratio and traction ratio make the bubble thickness difficult to control; 5 The pulling speed is not constant Changes are constantly occurring, which of course affects the thickness of the film. Remedy: 1Adjust the die gap at the nose to ensure uniformity throughout; 2Adjust the head die temperature to make the die part temperature uniform; 3Adjust the cooling device to ensure the air output from the air outlet is even; 4Adjust the inflation Ratio and traction ratio; 5 Check the mechanical transmission to keep the traction speed constant. 6. The thickness of the film is too thick. Causes of failure: 1 die gap and extrusion volume is too large, so the film thickness is thicker; 2 the air volume of the cooling air ring is too large, the film cooling too fast; 3 the pulling speed is too slow. Remedy: 1Adjust the gap of the die mouth; 2Adequately reduce the air volume of the air ring to make the film blown further so as to make it thinner; 3Properly increase the traction speed. 7.Thickness of the thin film is thin. Cause: 1 Die mouth The gap is too small, the resistance is too large, so the film thickness is thin; 2 the air volume of the cooling air ring is too small, the film cooling is too slow; 3 the traction speed is too fast, the film is stretched too much, so that the thickness becomes thinner. The solution: 1 Adjust the die gap; 2 Appropriately increase the air volume of the wind ring to speed up the cooling of the film; 3 Decrease the traction speed appropriately. . Poor heat sealability of the film Causes of failure: 1 The dew point is too low and the polymer molecules are oriented. As a result, the performance of the film is close to that of the oriented film, resulting in a decrease in heat sealing performance; 2 Insufficient blow-up ratio and traction ratio (too large), thin film Tensile orientation occurs, affecting the heat sealability of the film. Solution: 1 Adjust the size of the air volume in the air ring to make the dew point a bit higher. As far as possible, blow and traction under the melting point of the plastic to reduce the molecular stretch orientation caused by inflation and traction; 2 Blow-up ratio and The traction ratio should be smaller than appropriate, if the blow-up ratio is too large, and the traction speed is too fast, the transverse and longitudinal stretching of the film is excessive, then the performance of the film tends to be biaxially stretched, and the heat sealability of the film will be Worse. 9. Longitudinal tensile strength difference of the film Causes of failure: 1 The temperature of the molten resin is too high, and the longitudinal tensile strength of the film is decreased; 2 The pulling speed is slow, and the orientation effect of the film in the longitudinal direction is not enough, so that the longitudinal tensile strength is deteriorated; 3 Blow-up ratio is too large, does not match the traction ratio, so that the film's transverse orientation and tensile strength increase, and the longitudinal tensile strength will deteriorate; 4 film cooling speed is too fast. Solution: 1 appropriately reduce the temperature of the molten resin; 2 properly increase the traction speed; 3 adjust the blow-up ratio to make it suitable for the traction ratio; 4 properly reduce the cooling rate. 10. The film transverse tensile strength difference causes the fault: 1 the traction speed is too fast, and the blow-up ratio is too different, so that the longitudinal fibrosis, the lateral strength becomes worse; 2 the cooling speed of the cooling air ring is too slow. Solution: 1 Properly reduce the traction speed so as to match the blow ratio; 2 Increase the air volume of the air ring to allow the blown film to cool rapidly and avoid being stretched and oriented in a high temperature and high elasticity state. 11. Causes of bubble instability: 1 Excessive extrusion temperature is too high, the fluidity of the molten resin is too large, the viscosity is too small, and it easily fluctuates. 2 The extrusion temperature is too low, and the discharge rate is small; 3 The air volume of the cooling air ring Unstable, bubble cooling uneven; 4 interfered with and affected by strong external airflow. Solution: 1 adjust the extrusion temperature; 2 adjust the extrusion temperature; 3 check the cooling air ring to ensure that the amount of air around the uniform; 4 prevent and reduce the interference of the outside air flow.
12, the film surface roughness, irregularities Causes of failure: 1 extrusion temperature is too low, poor plastic resin; 2 extrusion speed is too fast. Solution: 1 Adjust the extrusion temperature setting, and increase the extrusion temperature properly to ensure that the resin plasticizes well; 2 Reduce the extrusion speed appropriately. 13. The film has odor problems Causes: 1 Resin raw material itself has odor; 2 Extrusion temperature of the molten resin is too high, causing the resin to decompose, resulting in odor; 3 bubble cooling is insufficient, the hot air within the bubble does not rule out clean. The solution: 1Replace the resin raw material; 2Adjust the extrusion temperature; 3Improve the cooling efficiency of the cooling air ring to make the bubble fully cooled.