PVC foam board is widely used in daily life. PVC foam board manufacturers often have various problems in the process of processing and production. Below we discuss and analyze the common problems of PVC foam board.
Insufficient external sliding performance
The temperature of the pvc foam board extrusion line is not easy to control, and it is easy to heat up, resulting in high temperature of the confluence core, large bubbles, string bubbles, yellowing and other problems in the middle of the board, and the surface of the board is not smooth.
The precipitation will become serious, which is manifested in the structure in the mold and the precipitation on the surface of the sheet, and it will also manifest as some individual phenomena moving back and forth on the sheet surface irregularly.
Insufficient performance of internal sliding
It is difficult to control the thickness of the board surface, which is manifested as thick in the middle of the board and thin on both sides; too much internal slippage, and the phenomenon of high temperature of the confluence core is easy to occur.
PVC foam board surface bending
Cause analysis: uneven material flow or insufficient cooling, the factors that cause uneven material flow are generally large traction fluctuations or unbalanced internal and external lubrication in the formula.
Çözüm: Check whether the cooling water circuit is unobstructed, so that the board surface is cooled evenly in place, and check the tractor to make the traction speed stable; adjust the amount of lubricant to balance the lubrication and the current.
The surface of the PVC foam board turns yellow
Reason analysis: The temperature of the barrel and the mold is high, and the lubricant is not well matched. After the thickness of the board is passed, the heat dissipation of the yellow heat core layer is slow, which is also related to the stability of the stabilizer.
Çözüm: Appropriately reduce the mold temperature, select high-efficiency lubricants and adjust the lubrication mix, reduce the amount of yellow hair and increase the amount of white hair for thick plates, and choose a stabilizer with better thermal stability. You can choose Qingdao Jiabaite’s environmentally friendly calcium and zinc stabilizer WD-1.
Uneven thickness of PVC foam board
Reason analysis: uneven discharge
Çözüm: The opening of the die lip can be adjusted. If the flow rate is too large, the choke rod can be adjusted. The formula is adjusted. Generally, the inner lubrication is more thick, the middle is thicker, and the outer lubrication is more. The two sides feed faster. Adjust the amount of internal and external lubricants according to the actual situation.
Changes in the thickness and texture of the sheet that are prone to occur when the shift is handed over
Reason analysis: related to mixing
Çözüm: After mixing in the last shift, the mixing interval is long after the next shift, the mixing tank is well cooled, and the first pot of mixing is pre-plasticized, which is different from the previous mixing. When the conditions remain unchanged, fluctuations are likely to occur, which can be solved by adjusting the traction, processing temperature or through management.
There are bubbles or bubbles in the cross section
Reason analysis: It can be attributed to one point, that is, the melt strength is not enough. 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.
Çözüm: Adjust the amount of foaming regulator and foaming agent, and choose a foaming agent with higher melt strength and viscosity; appropriately reduce the amount of PE wax as an external lubricant, and appropriately increase the temperature of the screw barrel to make plasticization better.
Six common sense of PVC foam board processing
The processing characteristics of PVC foam board are roughly the same as those of wood processing, as long as the working temperature is too high to cause scorching, and the chips generated after processing can be collected and recycled to reduce costs. There is one thing to pay attention to when cutting the hollow foam board, because the hollow space is 23mm, which is convenient for assembly. Positioned by means of a pin, which is convenient for processing.
- It can be formed by engraving machine according to the design drawing, and then the surface should be pasted with melamine board or baking paint; however, it should be noted that if the surface of the hollow foam board is uneven, only 2mm PVC board can be used as the material of vacuum overmoulding.
- Bending forming is only suitable for solid foam board, hollow foam board is not suitable; the processing method is to use upper and lower molds, cover the surface of wooden mold with aluminum plate and heat the solid foam board to a plasticizing temperature of 70~90℃ During the time, the surface of the foamed plate is directly extruded by the upper and lower molds without any change.
- During the manufacture of self-adhesive PVC, the surface can be printed with wood grains of different textures according to the requirements, which can save unnecessary processing procedures.
- The surface of the PVC foam board can be treated with baking paint, and the general categories can be divided into general baking paint, piano baking paint, and ceramic baking paint according to different processing methods; when the piano baking paint is processed, anti-UV ingredients will be added to avoid changes in the surface color; In terms of surface hardness, ceramic baking varnish is the best and has the advantage of anti-scratch.
- Next is the common processing method, which is pasted with crystal board (usually single-sided colored acrylic board), melamine board and melamine paper on the surface. In the edge-sealing part, most automatic edge-banding machines are generally processed. Mainly, the automatic edge banding machine is divided into two types: roller type and crawler type. However, if hollow foam is used, it is recommended to use the color similar to the surface covering material, so as to avoid obvious color difference when the paper shrinks after being attached. .
- Drilling can be beneficial to the crawler-type edge banding machine, which is less likely to cause unevenness on the surface after edge banding, and the pressure adjustment is also quite important; the color of the foam board is also directly drilled with NC machines. The material itself can reduce the density and increase the air content of the foam board itself according to the needs of the application, so as to achieve the effect of heat insulation and sound insulation and cost reduction. For example, the density of 15mm foam board reduces its own weight and the same volume of 10mm foam board Same weight.
PVC foam board Inspection Notes
- Board surface: smooth and flat hand feeling, no obvious mechanical texture, no color difference on the surface, milky white, no stains on the surface, no obvious small pits, no pinholes, no coarse pinholes, and no cracks. Note: The non-milk white foam board is deeply recycled into the waste board, which is not an environmental protection board, and the environmental protection board does not contain lead (the content is less than the European and American standards).
- Plate side plate: The incision is flat, the pores are fine, no pinholes, no coarse holes, no serious powder drop, no honeycomb holes, the cutting fibers fall off by themselves, and do not pop out. Note: Pay attention to the above situation, the follow-up process of making finished products is troublesome.
- Thickness measurement: When the caliper is placed on the surface of PVC foam board, the contact is close and there is no gap, the left and right thickness are uniform, the left, middle and right measurement, whether the deviation is large, the thickness deviation plus or minus 0.2mm is normal.