PVC wall panel is a kind of PVC product that has risen rapidly in recent years. The products quickly win customers' love with the advantages of environmental protection, beauty, moisture resistance and convenient installation. In the process of pvc wallboard extrusion, the common abnormal conditions are: wall panel is not straight, wall panel is uneven, surface is not smooth, density is high, wave pattern, toughness is not good, etc. How should we encounter these problems? Solve it?

Wall panel is not straight

First of all, it is necessary to check whether the sizing die and the die are aligned. Generally, the wall panel is bent upward because the sizing die and the die are not aligned and the position is high; and the wall panel is bent downward because the sizing die appears. Low condition.

In the case where the sizing die and the die have been aligned, check whether the water cooling groove, the traction, and the saw table are aligned with the sizing model.

After these reasons are ruled out, there are two possible reasons for not being straight:

1)The cooling of PVC wallboard products is not enough. Secondly, the temperature after the water cooling tank is still relatively high, and it is twisted under the condition of external force. The specific adjustment method is to increase the cooling water volume of the shaping die and the water cooling tank or to reduce the cooling. Water temperature, no longer directly reduce the speed of production.

2)The speed of discharge on both sides is inconsistent. Adjustment method: observe the temperature on both sides of the mold and observe for half an hour. If there is no change, which side is slower, which side will rise by a few degrees, or which side is discharged. I will quickly lower the temperature by a few degrees.

PVC wall panels are uneven

Generally, the unevenness of the wall panel is mainly in the vacuum shaping section of the sizing die. If the degree of vacuum is not enough, or the cooling water of the fixed mold is not enough, the adjustment method is to increase the amount of cooling water in the part, and increase the vacuum degree by water seal to accelerate the cooling rate of the wallboard products. If the local water is still open to the maximum, it is not flat, then the mold is removed to clean the vacuum circuit.

The overall surface of the wallboard is not smooth

The reason is that the overall temperature of the mold is too high or the vacuum pump of the extruder main machine is not working properly. Adjustment: Reduce the temperature of the mold by a few degrees or clean the vacuum pump of the extruder.

Wall board crack

See if the wall panel has broken water. Or the content of lubricant in the formula is too high, especially the amount of external lubrication is too high. Or use a relatively inferior stabilizer, the amount of internal and external lubrication is too much, and the stable composition is less

The density is too high, the foaming is not good

First of all, look at whether the lubrication is balanced, the lubrication is too much, the melt strength is reduced, the cells become larger, and the density increases. Once again, the amount of the blowing agent can be appropriately reduced or the amount of the adjusting agent can be increased to see if it is effective, and the adjustment is made according to the feedback.

Surface wave pattern

The main reason is the uneven discharge, which causes the uneven discharge: plastic over-melting is too soft; material flow is uneven; traction and extrusion are not matched; melt strength is too large and rebound

We can solve this in the following aspects:

First, the process:

1) Reduce the production speed, such as screw speed, feeding speed, etc., and increase the traction speed appropriately; sometimes the wave pattern is adjusted in production.

2) Reduce the extrusion temperature, especially the temperature of the plasticizing section of the third and fourth zones. Many enterprises now produce wainscoting boards using small tube materials, plastic steel materials or foamed sheets for production. These materials belong to secondary processing materials, and plasticization is extremely fast. Appropriate reduction of plasticization has certain advantages for production and product stability.

Second, the equipment:

1. Increase the gap of the screw, reduce the shear properly, and slow down the plasticization;

2. Clean the die and polish it, especially at both ends of the die to make the molten material flow smoothly.

3, check the mold has problems, such as forgetting to install the positioning pin, or whether the screw has problems, such as disagreement, etc., this will cause the material flow bias, generally only on the side of the material more wave pattern, and it is difficult to eliminate by adjusting the formula.

Third, the formula:

1. Appropriately increase the amount of external lubrication and reduce the amount of internal lubrication, but not too much adjustment

2. Under the premise of not affecting the foaming, the foaming regulator can be appropriately reduced or the foaming regulator with a small melt strength can be selected. In this case, the material of the die is prevented from being cut only when the melt strength is too large. The wavy pattern is formed due to excessive rebound of the melt strength.

Bad toughness

The first is to use too much secondary materials such as plastic steel and small pipe. Secondly, consider whether the amount of external lubrication is too high, especially the use of cheap stabilizers. In order not to paste, the dosage will increase, which will lead to more external lubrication of the overall formulation. Consider again whether the plasticization of PVC material is in place, and poor plasticization or over-plasticization will make the product brittle. Finally, if these problems are ruled out or if the toughness is not enough, the toughening modifier CPE-135A can be added as appropriate.

Pay attention to the state of the equipment, the surrounding hygiene and discipline during the production of PVC wallboard. The state of the equipment should pay attention to

(1) Whether the host current and the head pressure are suitable

(2) The temperature on the temperature control table and whether each ammeter can work normally

(3) Is the temperature of the main motor and the gearbox too high?

(4) Is the vacuum pump normal?

(5) Whether the thermocouple of the mold can be inserted into the end

(6) Whether water and electricity are normal.