Extrusion & Post
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Blocking/Poor Opening Property of High-Density Polyethylene Film
Problem Phenomenon
The film layers stick together and are difficult to separate, affecting subsequent processing and use.
Poor opening property is particularly prominent in film winding and automatic packaging, reducing production efficiency.
Cause Analysis
（1）The surface tension of the high-density polyethylene film is high, and the interlayer adhesion force is large
（2）The film is wound at a high temperature, and the cooling is insufficient
（3）The winding tension is too large
（4）Lack of anti-blocking agent
（5）The thinner the film thickness, the easier it is to block
Solution
（1）Add an appropriate amount of anti-blocking agent (such as silica fine powder 0.1-0.5%)
（2）Ensure the film is fully cooled before winding, with the winding temperature not exceeding 40°C
（3）Appropriately reduce the winding tension
（4）Add an appropriate amount of slip agent (such as oleamide 0.1-0.3%) to reduce surface friction
（5）Control the film thickness within a reasonable range
Key Takeaway
Film blocking is caused by surface tension and temperature, and needs to be solved by adding anti-blocking agents and controlling winding conditions.
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