Poor plastication

The product shows white opaque particles and rough surface; material not fully plasticated, with unmelted resin particles visible in cross-section. Poor plastication is the opposite extreme problem to excessive plastication in calendering — insufficient temperature or inadequate mixing time prevents the resin from fully melting and fusing. Products with poor plastication show greatly reduced mechanical properties, transparent products lose light transmittance, and both appearance and function are unqualified.

1. Operational factors: Feed temperature too low. 2. Comprehensive factors: Insufficient mixing/banburying time. 3. Material/formulation factors: Low proportion of plasticizable components in the formulation. 4. Material/formulation factors: Resin particle size of the fed powder too large. 5. Roll gap adjustment factors: Crown and cross-angle compensation of calender rolls is the core means of controlling the transverse thickness distribution of the film. Crown design is based on roll deflection calculations; if it does not match the actual process load, it will cause abnormal transverse distribution of film thickness — thicker in the middle and thinner at both ends, or an inverse bow-shaped distribution.

1. Process parameter optimization and adjustment: Increase feed section temperature and mixing time. 2. Mold/tooling improvement and maintenance: Appropriately adjust plasticizer dosage or use a higher efficiency plasticizer. 3. Equipment inspection and system maintenance: Select resin powder with smaller particle size. 4. Systematic troubleshooting method: Troubleshooting of calendering problems follows the sequence "roll gap → roll temperature → feed → tension → cooling". First check and precisely adjust the roll gap crown and cross angle, then confirm the uniformity of each roll's temperature distribution, next check the feed bank shape and rolling behavior, further adjust the winding tension control parameters, and finally optimize the cooling roll temperature and contact method. Change only one variable at a time to confirm the effect. 5. Preventive management: Establish standardized process parameter cards and quality control limits for each mold/product, and regularly conduct process capability index (CPK) evaluations. For recurring problems, use fishbone diagrams or 5Why analysis to trace the root cause, and solidify countermeasures as PFMEA control points. Establish a regular equipment maintenance system and implement life management for key tooling such as dies/spinnerets/calender rolls/coating heads.

The essence of poor plastication is insufficient temperature or inadequate mixing time preventing the resin from fully melting. The core of the solution is "heat up + extend time + adjust formulation": increase feed temperature and banburying time, select resin powder with smaller particle size to increase plastication rate, and appropriately increase plasticizer dosage to reduce plastication temperature requirements.