Key Processing Points and Skills of Anti-Static PC Plastic
2026-04-28 11:44:03
Plastic Molds
Anti-static PC is modified by adding anti-static agents and conductive fillers on the basis of pure PC materials. It not only retains the high strength, high toughness, impact resistance and stable dimensional performance of PC, but also reduces surface resistance, eliminating common problems such as static adsorption, dust accumulation and electrostatic discharge breakdown. It is widely used in electronic insulating parts, precision shells, dust-free workshop components, storage turnover parts and other fields. Compared with ordinary PC, modified anti-static formula has obvious differences in fluidity, thermal stability and precipitation characteristics, with narrower molding window and higher processing control requirements. Reasonable control of raw material management, mold conditions, molding process and post-treatment details can stabilize production quality and effectively avoid silver lines, bubbles, surface precipitation, dimensional defects and attenuation of anti-static performance.
1. Raw Material Drying and Storage ControlAnti-static PC is extremely sensitive to moisture absorption and precipitation of anti-static agents. Damp raw materials are easy to produce silver lines and bubbles under high temperature molding, and destroy the uniform distribution of conductive components, resulting in local failure of anti-static effect. Raw materials need strict drying treatment with conventional drying temperature controlled at 90℃ to 110℃ and drying time maintained for 4 to 6 hours. Closed hot air drying is adopted to avoid uneven local heating. Modified anti-static PC cannot be stored at high temperature for a long time. Long-term material retention in the barrel will cause decomposition and carbonization of anti-static additives, resulting in black spots and oily precipitates on product surfaces.
Adopt closed hopper and dehumidifying and drying integrated equipment in the whole production process to prevent secondary moisture absorption of raw materials. The mixing ratio of recycled materials should be strictly controlled, and mixed recycled materials should be minimized to prevent uneven filler dispersion and increased performance fluctuation.
2. Barrel Temperature and Plasticization Parameter Setting
Anti-static PC has high melt viscosity, and conductive fillers are prone to agglomeration and degradation under strong shear heat. Temperature setting needs to balance fluidity and material stability. Segmented temperature control is adopted for the barrel with low temperature in the feeding section, reasonable heating in the melting section and appropriately reduced nozzle temperature, preventing melt retention and decomposition at the nozzle. The overall molding temperature is 10℃ to 20℃ lower than that of ordinary PC to avoid volatilization and surface whitening precipitation of anti-static additives under high temperature.
Medium and low back pressure is adopted to stabilize plasticization, reduce shear friction heat and prevent agglomeration of conductive components caused by excessive shear. Reduce screw speed to cut down melt shear stress, ensure uniform dispersion of fillers, and avoid local color difference and stress concentration of products.
3. Injection Filling, Holding Pressure and Cooling TechnologyAnti-static PC has weak fluidity and large filling resistance. Medium and high speed stable mold filling is required to prevent premature cooling of melt surface under low-speed slow flow, resulting in flow marks and weld lines. Multi-stage injection control is applied, with slow transition in the runner section, uniform filling in the main cavity section and slow buffering at the end, preventing jet lines and internal voids caused by high-speed injection. Moderate holding pressure and shortened holding time are adopted. Excessive holding pressure will intensify molecular chain compression, induce internal stress, and accelerate the migration of anti-static additives to the surface, forming white fog and mold sticking.
Sufficient and uniform cooling time is essential. The shrinkage rate of anti-static modified materials is slightly higher than that of pure PC. Insufficient cooling will lead to later shrinkage, deformation and warpage. Adequate cooling can stabilize product size and reduce residual internal stress.
4. Mold Conditions and Surface Treatment RequirementsMold temperature directly affects product appearance and additive precipitation. The recommended mold temperature of anti-static PC is 70℃ to 95℃. Appropriate mold temperature improves melt fluidity, optimizes weld lines, slows down rapid precipitation of anti-static agents, and keeps the surface clean without oil fog. Moderate cavity polishing level is required. Excessive mirror polishing is easy to adsorb additive precipitates and form hazy white fog after long-term production. Matte and textured molds are more suitable for anti-static PC molding and less prone to precipitation defects.
The mold exhaust system must be unobstructed. This material is easy to produce trace decomposed gas under high temperature, and air trapping will cause scorching, black spots and reduced weld line strength. Reasonably arrange exhaust grooves at weld lines, flow ends and dead corners. Prefer side gate and fan gate to reduce excessive shear heat and prevent scorching and whitening defects at the gate position.
5. Demolding and Common Defect PreventionWith trace additive precipitation, anti-static PC has greater demolding resistance than ordinary PC. Release agents should be used as little as possible or not at all. Frequent spraying of release agents will mix with surface anti-static layers, causing unstable resistance and sticky surface. Improve demolding performance by optimizing mold polishing and reasonable draft angle, and ensure smooth operation of ejection mechanism to avoid ejection white marks and cracking.
Common defects such as white spots and white fog are mostly caused by additive precipitation at high temperature, which can be improved by reducing material temperature, increasing mold temperature and shortening material retention time. Obvious weld lines can be solved by optimizing gate position, increasing holding pressure and strengthening local exhaust. Regularly clean residual precipitates in cavities and runners to avoid batch appearance defects caused by scale accumulation.
6. Post-Treatment and Performance Protection
Residual internal stress exists in anti-static PC products after molding. Low-temperature annealing treatment is required for precision parts at 60℃ to 80℃ with constant temperature heat preservation and slow cooling, eliminating internal stress and improving cracking resistance and environmental adaptability. Finished products should be stored in dry and ventilated conditions to avoid high-temperature closed stacking. High temperature environment will accelerate the migration of anti-static additives, resulting in sticky surface and increased dust absorption. Secondary processing such as drilling and bending should avoid strong extrusion and sharp scratching to prevent damage to the surface conductive structure and ensure long-term stable anti-static performance.
ConclusionThe molding difficulties of anti-static PC focus on the thermal stability of modified additives, filler dispersion, easy precipitation and high internal stress. The core processing principle is low temperature, low shear, stable drying, controlled mold temperature and reduced chemical pollution. Comprehensive standardized processing procedures formulated from raw material drying, temperature plasticization optimization, filling and holding matching, mold exhaust design and daily maintenance can effectively solve appearance defects such as silver lines, white spots, weld lines and sticky surface precipitation, stably control surface resistance parameters, extend service life, and meet the batch molding demands of electronic and industrial dust-free accessories.
