Film surface blooming

The "film surface blooming" in blown film production refers to the appearance of uneven streaks, spots, or hazy areas on the film's surface, which negatively affects the film's appearance and quality.

Raw Material Issues:

1. Poor quality raw materials: The presence of impurities or contaminants can cause blooming on the film surface.

2. Mixing different batches or grades of raw materials: Variations in melt flow indices can lead to inconsistent flow, resulting in uneven surfaces.

Troubleshooting:

1. Use high-quality raw materials, avoiding those with excessive impurities or too much recycled content.

2. Ensure consistency in raw material batches, and avoid mixing materials with different melt flow indices or grades.

3. Thoroughly dry the raw materials before use to reduce the impact of moisture on the film surface.

Improper extruder temperature control:

1. Uneven temperature control in each section of the extruder, especially when the temperature is too high or too low, may cause uneven melt fluidity and cause the film surface to bloom.

2. Excessive temperature may cause excessive degradation or oxidation of the raw materials, resulting in uneven surface.

Troubleshooting methods:

1. Check and optimize the temperature settings of each section of the extruder to ensure stable and uniform temperature control.

2. Avoid excessively high or low temperatures, especially pay attention to the control of the die temperature and keep it within an appropriate range.

Poor cleanliness of die head：

1. Carbon deposits and impurities exist on the surface or inside of the die head, which hinder the flow of the melt and cause the film surface to become flowery.

Troubleshooting methods:

1. Clean the die head regularly, especially when changing raw materials or production batches, to prevent carbon deposits and impurities from remaining.

2. Check whether the die lip is flat and smooth, and polish it if necessary.

Uneven cooling:

1. Uneven air volume distribution of the air ring or inappropriate temperature of the cooling air may cause uneven cooling of the film and cause surface blooming.

Troubleshooting methods:

1. Adjust the air volume and wind direction of the air ring to ensure uniform cooling of the film.

2. Check the temperature of the cooling air to ensure that it is within the appropriate range to avoid overcooling or overheating.

Improper traction speed:

1. The traction speed does not match the extrusion speed, which may cause uneven stretching of the film surface, resulting in stripes or spots.

Troubleshooting methods:

1. Adjust the traction speed to match the extrusion speed to ensure uniform tension of the film during traction.

2. Check the stability of the traction system to avoid speed fluctuations or mechanical failures.

Environmental factors:

1. The temperature, humidity and air flow in the production environment may affect the surface quality of the film, especially in high humidity or low temperature environment, which is prone to surface floweriness.

Troubleshooting methods:

1. Control the temperature and humidity of the production environment and try to keep them constant.

2. Avoid airflow directly blowing into the film production area to reduce the impact of the environment on the surface quality of the film.