Matters needing attention in the production of PVC advertising foam board
Matters needing attention in the production of PVC advertising foam boardThere are some precautions introduced in the production of PVC foam board, and if these precautions are ignored by us, it is easy to have quality problems in later use. And its main chemical composition is polyvinyl chloride, and the places of use are mainly passenger cars, building exterior wall panels, interior decoration panels, offices, residences, buildings in public places, etc. Therefore, the quality requirements for its use are very high. Here we take a look.
According to the different foaming ratio, it can be divided into high foaming and low foaming. The softness and hardness of the foam body can be divided into hard, semi-rigid, and flexible foams. According to the cell structure, it can be divided into closed-cell foam and open-cell foam. The common common PVC foam sheet is a rigid closed cell low foam sheet. PVC foam board has the advantages of chemical resistance, weather resistance, flame retardancy, etc. It is widely used in many aspects, including display panels, signs, billboards, partitions, construction boards, furniture boards, etc.
In terms of sheet: if the stability is insufficient, it will affect the whole board surface and the board surface yellowing, and the foamed board is brittle. The solution is to reduce the processing temperature. If it does not improve, you can adjust the formula and increase the amount of stabilizers and lubricants added appropriately. You can also change them one by one. It is easy to find the problem quickly and solve the problem quickly. In addition, insufficient melt strength will result in large cells in the foamed sheet and very long longitudinal section.
After , determine whether the melt strength is insufficient. The direct method is to press the plate wrapped on the middle roll with your fingers after the three rolls. When the melt strength is good, you can feel the elasticity. If it is difficult to pop up after pressing, it indicates that the melt strength is poor. Because the screw structure and cooling method are quite different, it is difficult to judge whether the temperature is reasonable. In short, within the allowable load of the extruder, the temperature in zone 3 to 5 is better.
To obtain a uniform foam product in the foamed sheet, it is also necessary to ensure that the PVC material has a good melt strength. Therefore, the quality of the foaming regulator is very important. For example, in addition to the basic function of a general-purpose processing aid, the foaming regulator also has a high molecular weight and a strong melt strength, which can significantly improve the melt strength of the PVC mixture. , To prevent bubble fusion and rupture, so as to achieve a more uniform cell structure and lower product density, while also improving the surface gloss of the product. Of course, the amount of yellow foaming agent and white foaming agent should be matched well.
Lubricant balance: the performance of insufficient external slip, the temperature of zone 5 of the extruder is not easy to control, and it is easy to heat up, resulting in high temperature of the confluent core, large bubbles in the middle of the sheet, stringing, yellowing, etc., and the surface of the sheet is not smooth; Precipitation will become serious due to excessive slippage, and the precipitation in the structure inside the mold and the surface of the plate will also be manifested as some individual phenomena moving irregularly back and forth on the board surface. Insufficient internal slip indicates that the board surface is difficult to control the thickness, which is manifested as a thick middle plate and thin on both sides; too much internal slip is prone to the phenomenon of high temperature of the confluent core.
Attention should be paid to avoid some problems that destroy its properties during the production of PVC foam board, and its quality must be improved. The protective role played by users in use can be better reflected.
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