The key production common sense of PVC

1. Basic raw materials of PVC Resin Calcium powder Stabilizer Lubricant Modifier

2. Process flow from raw materials to finished products Mixing - silo - screw - shaping - (mold) cooling - traction - shearing

3. Physical and chemical properties of PVC: white powder with an amorphous structure, translucent and glossy, starts to decompose at about 133 degrees, poor stability to light and heat, fully decomposes to produce hydrogen chloride when exposed to sunlight above 100 degrees or longer, (white-yellow line- red-brown-black) factors: stabilizer, temperature, lubricant.

4. Resin: commonly used are SG5 type (commonly used for pipes) and SG8 type (commonly used for pipe fittings), PVC basic raw materials,

Calcium powder is divided into light calcium, heavy calcium, and nano-calcium, adding too much calcium powder will affect the quality. The number of servings is about 10-15 servings)

Light calcium: the quality of the product is good (the tube is hard) and it is mostly used on pipe fittings

Heavy calcium: good appearance (soft pipe) mostly used on pipes

Stabilizer: calcium zinc, lead salt (toxic), organic tin Function: prevent resin from decomposing, adding too much will affect plasticization, and adding too little will have a bad effect.

Lubricant: PE wax, paraffin (external lubrication) to prevent objects from adhering to the equipment, stearic acid (internal lubrication), fused with resin to reduce intermolecular friction.

Plasticizers: Common lipids.

5. Products with simple shapes are generally extruded products (drainage pipes, threading pipes), and products with more complex shapes are generally injection molded products (pipe fitting profiles)

6. Vicat - the critical value of softening temperature, the temperature at which a 1mm2 indenter is pressed into a depth of 1mm under a certain load and a certain temperature.

7. Titanium dioxide - refracts yellow light, whitening agent - absorbs ultra-violet ultramarine blue and phthalocyanine blue, both of which are used to adjust the color, and the amount of 15g is very small.

8. CPE (common) will be soft if added too much, and will be brittle if added too little. The quality of CPE on the market is uneven. It is recommended to use the modifier CPM in the same formula.

9. The threading tube turns yellow: the stabilizer is insufficient, the temperature is too high or not resistant to temperature, and it has been plasticized. Redness: It may be a problem of refraction, or it may be plasticized. Brittle: more lubrication, external lubrication is greater than internal lubrication.

10. When the PVC pipe is discharged, it is fast and slow, because the external lubrication is too much, and the current is unstable at the same time

11. To improve thermal stability, it is recommended to use our company's HK-8201 (high melting point, non-volatile, non-precipitating)

12. The single screw or too much calcium powder must be granulated.

13. The reason why the inner wall of the product is not smooth The external lubrication is less, and the internal and external lubrication is uneven.

14. Reasons for current instability Lubrication problems (more)

15. What is the problem with the pipe bend, it may be a mold problem or a cooling problem.

16. What is the reason for the thorns on the plate: less lubrication and insufficient later lubrication

17. The quality of PVC pipes in the same pot is sometimes good and sometimes bad, the mixing is uneven, and the vacuum transportation distance is too long, which causes the mixed materials to be scattered again due to the problems of density and quality.

18. The pipe has lumps: plasticization problems, lubrication problems.

19. The head of PVC granulation is always pasted: less stabilizer, higher temperature, and less lubrication.

20. Air bubbles inside the fitting: plasticized.