Components of WPC formulation system

Components of WPC formulation system

1. PVC resin.

The processing of plastic profiles generally uses a hard resin with a degree of polymerization of 1000 (SG5 type) and a K value between 66 and 68. Although the grades and production processes of resin suppliers are different, the resin selection of general profile manufacturers is fixed and will not be changed at will. However, there are batch instability factors in the resin produced by the acetylene method, if you choose to use the same batch.

Moreover, the colorant is composed of three parts: carrier, colorant and additives. The colorant has a certain degree of incompatibility with PVC resin. Therefore, when selecting the carrier of the colorant, it should be the same type as the resin to be colored. 

2. Stabilizer.

Stabilizers have a positive impact on the light fastness and weather resistance of plastic products. Stabilizers are divided into heat stabilizers and light stabilizers. In the same way, such additives should not only be added to the profile formula, but also the colorant itself, and must be consistent with the model, batch, and manufacturer in the profile formula.

3. Antioxidants.

Antioxidants have a good protective effect on the color of polymers. Generally, the combination of primary and secondary antioxidants has excellent thermal stability and oxidation resistance. At present, the most widely used in the plastic industry is 1010. Generally, it can exert synergistic effect when used in conjunction with ETHAPHOS368, BTHANOX310 or DLTP, and the dosage is generally between 0.3-1.0%.

4. UV absorber.

The addition of UV absorbers to polymers can reduce sunlight damage to polymer resins, but cannot completely prevent such damage. Experiments have shown that adding UV absorbers cannot protect the surface of the polymer because it first works inside the polymer, so the purpose of adding UV absorbers is to deactivate free radicals before the polymer chain reaction begins. Commonly used models are UV-9, UV-531, UV-35, UV-327, etc., and UV-531 is more commonly used in plastic profiles. And the combined use of UV absorbers and hindered amines (HALS) has a chemical synergistic effect.

5. Lubricant.

The selection of lubricant in the formula is also very critical, a good lubricant will give the plastic profiles a high-quality finish. Generally, oxidized polyethylene wax, PE, OPE, EBS, etc. are used. Try not to use paraffin wax. Severe precipitation of paraffin wax during extrusion will shorten the mold cleaning time, affect the finish of the product, and in severe cases will directly affect the physical properties of the profile.

6. Other additives

During the processing of plastic profiles, resins and colorants will generate static electricity when they flow in powder state. Adding antistatic agent can avoid the bridging phenomenon caused by static electricity when powder is conveyed and fed.

When adding a colorant to the formula to produce the same full-body colored plastic profile, the formula of the profile remains unchanged. The switching of any additive will affect the color, especially the color difference of the profile product caused by the switching of the stabilizer or calcium carbonate. .