Processing Machinery
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Batch-to-batch color hue fluctuation in profile processing
Problem Phenomenon
With the same calcium-zinc PVC formulation, profile products produced on different dates have uneven chromaticity, the yellowness index YI fluctuates by more than 3 units, and customers complain about inconsistent colors.
Cause Analysis
Fluctuations in the metal soap ratio in calcium-zinc composite stabilizers cause changes in thermal stabilization effects; batch differences in the whiteness of raw material PVC resin are not compensated in time; insufficient temperature control accuracy of processing equipment causes local overheating; auxiliary stabilizers such as β-diketones partially decompose and are lost at high temperatures.
Solution
Establish a raw material batch inspection system to control the calcium-zinc stabilizer metal content ratio Ca:Zn=1:1~2:1; add 2-3 phr fluorescent brightener OB or OB-1 to the formulation; regularly calibrate the equipment temperature control system to control the temperature difference within ±2°C; adopt a pre-mixing process to ensure uniform dispersion of auxiliary stabilizers.
Key Takeaway
Color hue stability control requires systematic optimization from three dimensions: raw material consistency, formulation design, and equipment accuracy, rather than solely adjusting the stabilizer dosage.
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