How to solve the problem of air holes in PVC foam board?

2022-05-30   Pageview:22

Mainly because the foaming agent is too much or the foaming regulator is not enough, the ratio of the two is not coordinated, or the quality of the foaming regulator is problem; poor plasticization, low processing temperature or excessive lubrication.

If a large area of ​​cells appears on the surface of the foamed product, the foaming regulator treatment can be adjusted appropriately; if individual cells occasionally appear on the surface of the foamed board, it is likely that the mixing procedure, temperature, and feeding procedure are not followed. Mixing is not uniform.

Solution:

(1) In the early stage of production of the plate, it is necessary to carefully check whether the wall thickness of the produced plate is compatible with the plate thickness specified by the mold. The corresponding mold should be selected according to the thickness of the plate. If a thin plate mold is used to produce a thicker plate, the occurrence of local bubbles is inevitable.

(2) If there are bubbles in local positions during production, appropriately reduce the die oil temperature to improve the melt strength.

(3) Reduce the die gap of the corresponding part to improve the melt pressure.

(4) Properly adjust the temperature of the confluent core of the extruder to suppress over-plasticization or under-plasticization of the melt and improve the melt strength.

(5) Correspondingly increase the die temperature at the cell part, so as to increase the flow rate and increase the melt density.

(6) Properly adjust the traction speed to solve the problem of too fast or too slow traction speed, reduce the extrusion stress or tensile stress on the melt, and eliminate bubble breakage.

(7) Appropriately reduce the gap between the first setting plate and the second plate, and reduce the melt pressure before complete cooling and before the strength is formed.

(8) Appropriately reduce the dosage of recycled materials with complex components to facilitate the homogenization of material components.

(9) Whether the calcium carbonate used in production is activated must be tested and demonstrated before production. Appropriately reduce the calcium carbonate content in order to improve the melt strength.

(10) Appropriately adjust the internal lubricant or stabilizer to improve the dispersibility and stability of the material.

PE wax external lubricant has a great influence on melt fluidity, surface finish of foamed products, mixing and distribution of foaming gas. Tianshi New Material reminds that according to the fluidity of the melt, it is advisable to use a lubricant that balances internal and external lubrication and a variety of lubricating compounds for the production of skinned foamed sheets. The external lubricant can improve the appearance of the product and facilitate demolding.

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