Today, Qingdao Sainuo pe wax manufacturer takes you to know the cause analysis and solutions of some problems in the production process of PVC sheet.

pe wax for PVC products

1. Surface yellowing of PVC sheet
(1) Cause: insufficient stable dose
Solution: increase the amount of stabilizer
(2) Cause: insufficient external lubrication, large friction, causing material decomposition
Solution: increase the amount of external lubricant
(3) Cause: the temperature is set too high
Solution: lower the temperature
The extrusion temperature is too high or the stability is not enough. Solution: reduce the processing temperature. If it doesn’t get better, adjust the formula, add stabilizer and lubricant appropriately, and change them one by one. It’s easy to find out the problem quickly and solve the problem as soon as possible.
2. Yellowing in the middle of plate surface
(1) Cause: the local temperature of the mold is set high
Solution: reduce the temperature of the corresponding place
(2) Cause: insufficient external lubrication
Solution: increase the amount of external lubrication
(3) Cause: high temperature in zone 5 of extruder
Solution: reduce the temperature of the corresponding place
The main reason is that the temperature of the core of the barrel is related to the high temperature of the die, the amount of lubricant is also related, and once again, it is related to the white foaming agent.
3. Uneven sheet thickness
(1) Cause: the gap of die lip is unreasonable
Solution: adjust the die lip thickness
(2) Cause: improper adjustment of choke block
Solution: adjust the choke block
(3) Cause: excessive external lubrication
Solution: reduce the external lubrication amount
(4) Cause: insufficient internal lubrication
Solution: increase the amount of internal lubrication
(5) Cause: unreasonable mold temperature setting
Solution: adjust the mold temperature
The opening of die lip can be adjusted due to uneven discharge. If the flow rate is too high, you can adjust the choke rod and adjust the formula. Generally, there is more internal lubrication, thicker in the middle, more external lubrication, and fast feeding on both sides.
4. The sheet is brittle
(1) Cause: the extruder temperature is set too high
Solution: lower the temperature
(2) Cause: the extruder temperature is set too low
Solution: increase the temperature
(3) Cause: unreasonable formula
Solution: adjust the formula
5. The surface of the sheet is not smooth
(1) Cause: insufficient external lubrication
Solution: increase the amount of external lubrication
(2) Cause: lack of processing aids
Solution: increase the amount of processing aids
(3) Cause: inadequate dispersion of fillers or additives
Solution: adjust the amount of filler or additives
(4) Cause: the mold temperature is set too low
Solution: increase the mold temperature
(5) Cause: the extruder temperature is set too low
Solution: increase the temperature
(6) Cause: Too high temperature setting of extruder and die
Solution: lower the temperature
6. There are stripes perpendicular to the extrusion direction
(1) Cause: the viscosity of foaming regulator is too high
Solution: adjust the type of foaming regulator
(2) Cause: the extruder temperature is set too low
Solution: increase the temperature
(3) Cause: the mold temperature is set too low
Solution: increase the mold temperature
(4) Cause: the traction speed is too fast
Solution: reduce the traction speed
7. There are big bubbles in the sheet
(1) Cause: insufficient melt strength
Solution: increase the amount of foaming regulator
(2) Cause: high temperature in zone 5 of extruder
Solution: reduce the temperature of the corresponding place
(3) Cause: the temperature of the corresponding die is too high
Solution: reduce the corresponding temperature
(4) Cause: impurities
Solution: pay attention to impurities in raw materials
8. Bending of sheet surface
(1) Cause: the temperature setting of three rollers is unreasonable
Solution: adjust three roller temperature setting
(2) Cause: the temperature difference inside the plant is large or the air convection is too fast
Solution: improve the plant environment
Uneven material flow or inadequate cooling. The cause of uneven material flow is generally large traction fluctuation or uneven internal and external lubrication in the formula. The machine factor is easy to eliminate. The formula adjustment is generally based on the premise that the external lubrication is as little as possible. Adjusting the internal lubrication will have a good effect and ensure uniform cooling in place.
9. Large cell of foam sheet
(1) Cause: high extruder temperature setting
Solution: lower the temperature
(2) Cause: the dosage of foaming regulator is small
Solution: increase the amount of foaming regulator
(3) Cause: improper lubrication adjustment
Solution: adjust the ratio of lubricant
10. The sheet thickness is not easy to control and moves back and forth
(1) Cause: too much external lubrication
Solution: reduce the amount of external lubrication
(2) Cause: mold temperature is unstable
Solution: correct the thermometer and improve the control accuracy
11. The bubbles in the core of the sheet are large and the bubbles on the surface are small
(1) Cause: high temperature of main engine
Solution: reduce the host temperature
(2) Cause: improper lubrication adjustment
Solution: adjust the lubricant ratio
(3) Reason: the strength of solution is insufficient
Solution: increase the amount of foaming regulator
12. There are bubble holes or bubble stratification in the cross section.
The reason can be summarized as follows: the melt strength is not enough.
The reasons for the insufficient strength of melt are as follows:
(1) The foaming agent is excessive or the foaming regulator is not enough, or the proportion of the two is not coordinated, or the foaming regulator has quality problems.
(2) Poor plasticization, low processing temperature or excessive lubrication.
13. Changes of sheet thickness and grain during shift handover
Main reasons: it is related to mixing. After mixing in the previous shift, there is a long interval between mixing in the next shift, the mixing barrel is cooled well, the mixing in the first pot is pre plasticized well, which is different from the previous mixing. Under other conditions unchanged, it is easy to produce fluctuations, which can be solved by adjusting the traction, processing temperature or management.
Qingdao Sainuo Chemical Co.,Ltd. We are 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!
Website：https://www.sanowax.com
E-mail：sales@qdsainuo.com
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Adress：Room 2702,Block B, Suning Building, Jingkou Road, Licang District, Qingdao, China