Extrusion & Post
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Blocking/Poor Opening of Polypropylene Film
Problem Phenomenon
The film layers stick together and are difficult to separate, affecting subsequent processing and use.
Poor opening is especially prominent in film winding and automatic packaging, reducing production efficiency.
Cause Analysis
(1) The surface tension of polypropylene film is high, and the interlayer adhesion is large
(2) The film is wound at too high a temperature, and the cooling is insufficient
(3) The winding tension is too large
(4) There is a lack of anti-blocking agent
(5) The film thickness is too thin, making blocking easier
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, and the winding temperature does not exceed 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 an anti-blocking agent and controlling the winding conditions.
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