Material Analysis
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PP Part Color Difference
Problem Phenomenon
With the same masterbatch, parts in the same batch vary in color depth, or obvious color difference exists between batches.
Cause Analysis
Uneven masterbatch dispersion (insufficient back pressure, inadequate mixing), melt temperature fluctuation affecting color development, regrind ratio changes, uneven masterbatch-base premixing, or insufficient feeding metering accuracy all cause color difference.
Solution
①Appropriately raise back pressure to improve masterbatch dispersion; ②stabilize melt temperature and regrind ratio; ③fully premix masterbatch with base material, using gravimetric feeding if necessary; ④check drying and feeding system metering accuracy; ⑤establish first-article color matching and sampling inspection systems.
Key Takeaway
For PP color difference, check 'dispersion and metering stability' first, then temperature; color difference often drifts with regrind ratio and feeding fluctuation—fixing these two variables is more effective than repeatedly adjusting masterbatch ratio.
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