Processing Machinery
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Random copolymer polypropylene extruded products excessive gel/gel particles
Problem Phenomenon
Transparent or translucent gel particles (gel particles) are visible in the extruded film or product, affecting product appearance and transparency.
Gels are insufficiently plasticized or crosslinked resin particles.
Cause Analysis
（1）The high molecular weight fraction in the raw material is not fully plasticized\
（2）Barrel temperature too low, part of the resin not completely melted\
（3）Insufficient screw mixing effect\
（4）The raw material contains crosslinked or oxidized gel\
（5）The filter screen mesh count insufficient, gel not intercepted
Solution
（1）Appropriately increase the barrel temperature to the higher value within the 190-260°C range\
（2）Optimize screw design, add mixing elements\
（3）Increase the filter screen mesh count to 80-120 mesh\
（4）Select high-quality raw material with low gel content\
（5）Check whether crosslinked material is mixed into the regrind
Key Takeaway
Gels are caused by insufficient plasticization or raw material quality problems, and need to be solved from temperature control, screw design and raw material selection.
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