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Do you know PVC foam board?

Do you know PVC foam board?

2022-03-21

The chemical composition of PVC foam board is polyvinyl chloride, so it is also called foam polyvinyl chloride board.

Five factors affecting the quality of PVC foam board

In the extrusion process of PVC foam board, the problems encountered can be basically classified into five categories. The first is the problem of stability; The second is melt strength; The third is lubrication; The fourth is the problem of decentralization. These four types of problems, especially the first three types of problems, will restrict and cross influence each other. From the surface phenomenon, it is sometimes difficult to distinguish them immediately. It is necessary to conduct in-depth observation and analysis to find the root cause of the problem.

pe wax for PVC foam board

(1) Insufficient stability will affect the whole board surface, which turns yellow and the foamed sheet is brittle

(2) Insufficient melt strength will lead to large foam cells and long longitudinal bubbles.

The most direct way to judge whether the melt strength is insufficient is to press the plate wrapped on the middle roll with your fingers behind the three rolls. When the melt strength is good, you can feel elasticity when pressing. If it is difficult to bounce after pressing, it indicates that the melt strength is poor. Because the screw structure and cooling mode are quite different, it is difficult to judge whether the temperature is reasonable. Generally speaking, the temperature in zone 3-5 is better to be low within the allowable load of the extruder. In order to obtain uniform foaming products in foamed pipes, it is also necessary to ensure that PVC materials have good melt strength. Therefore, the quality and model of foaming regulator are very important. Of course, yellow and white hair foaming agent should also be well matched.

(3) Lubricant

The lubricant is divided into external lubricant and internal lubricant. External sliding is conducive to demoulding and is beneficial to the smoothness of the plate surface. Too little external sliding makes it difficult to control the temperature in zone 5 of the extruder and easy to rise, which will lead to high confluence core temperature, large bubbles, string bubbles, yellowing and other problems in the middle of the plate, and the plate surface is not smooth; If there is much external sliding, the precipitation will be serious, which is reflected in the structure in the die and the precipitation of external sliding on the plate surface, and some individual phenomena will move back and forth irregularly on the plate surface. Internal sliding is conducive to plasticization and melt fluidity. Insufficient internal sliding makes it difficult to control the thickness of the plate surface, which is manifested in the thickness of the plate in the middle and thin on both sides; The phenomenon of high confluence core temperature is easy to occur due to more internal sliding.

(4) Poor dispersion will lead to the phenomenon that the plate surface is not smooth

Process temperature control: the three problems mentioned above are fundamental, basic and deep-seated. Compared with the above three problems, the process temperature control is much more intuitive. It is a surface problem, but poor temperature control will induce the emergence of fundamental problems. Increasing the processing temperature will reduce the material stability time and cause stability problems; The original lubrication balance will be broken, which is generally manifested in insufficient external lubrication. Especially in the later stage, the amount of external lubrication needs to be increased; The increase of temperature will also lead to the decrease of melt strength, the increase of foam cell, the decrease of cell number, the brittleness and fracture of foam sheet; The increase of temperature reduces the melt strength and also reduces the melt viscosity. The viscosity decreases and the shear dispersion ability decreases. For screws with weak dispersion ability, uneven dispersion sometimes occurs.

(5) The more foaming agent, the better foaming, the smaller density and the lighter?

In the actual production, we met many customers of PVC foam products. The products had large bubbles or the weight could not be reduced. We asked all kinds of expert friends and got the answer that made them believe: This is that the foaming agent was added less and did not grow up, so we had to add more foaming agent, which naturally grew up. As a result, the situation was worse, so they discussed another way to increase the amount of foaming regulator, and the results improved until the amount of regulator increased enough to avoid any problems.

Qingdao Sainuo Chemical Co., Ltd. We are a manufacturer for PE wax, PP wax, OPE wax, EVA wax, PEMA, EBS,Zinc/Calcium Stearate…. Our products have passed the REACH, ROHS, PAHS, FDA testing. Sainuo rest assured wax, welcome your inquiry!

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