Plastic additives The main purpose of adding additives to plastics is to improve processing performance, improve use efficiency and reduce costs. Additives account for a small proportion in plastic materials, but they have a great influence on the quality of plastic products. Different kinds of plastics need different kinds and dosage of additives because of different molding methods and using conditions. The main auxiliary equipment is as follows:

1, stabilizer

We all know that plastic products will fade, become brittle and crack under the action of light, heat and oxygen during processing, storage and use. In order to delay and prevent aging, stabilizers must be added. Mainly used to prevent thermal aging, known as heat stabilizer; Mainly used to prevent oxidative aging, called antioxidants; Mainly used to prevent photoaging, called light stabilizer, collectively referred to as stabilizer.

At present, the best plastic stabilizer is methyl tin heat stabilizer (18 1), which is very effective for calendering, extrusion, injection molding and blow molding of rigid polyethylene (pvc). Because of its high safety, it is especially suitable for food packaging and high-definition rigid polyethylene products. At the same time, it is also widely used in plastic doors and windows, water pipes and decorative materials to replace other highly toxic plastic heat stabilizers. It has been widely used in America, Europe and Japan. In recent years, 18 1 methyl tin heat stabilizer has been widely used in China.

2. Plasticizer

Plasticizers can increase the flexibility, ductility and plasticity of plastics, reduce the flowing temperature and hardness of plastics, and are beneficial to the molding of plastic products. Commonly used are phthalate, sebacate, chlorinated paraffin and camphor. The most common is camphor.

3. Flame retardant

Additives that can improve the flame retardancy of plastics are called flame retardants. Most plastics containing flame retardants are self-extinguishing or slow in combustion. Commonly used flame retardants include antimony oxide, aluminum and boron compounds, halides and phosphate esters, tetrachlorobenzene phthalic anhydride, tetraphthalic anhydride and so on.

4. Antistatic agent

Antistatic agents can eliminate or reduce static electricity generated on the surface of plastic products. Antistatic agents are mostly electrolytes, which have limited compatibility with synthetic resins and can migrate to the plastic surface to absorb moisture and eliminate static electricity.

5, foaming agent

Plastic foaming agent is a kind of low molecular organic matter that can be gasified at a certain temperature, such as dichlorodifluoromethane; Or organic compounds that decompose gases when heated. These gases remain in the plastic matrix, forming foam with many fine foam structures. Azo compounds and nitroso compounds are usually used.

6. Colorants

Colorants are used to color plastics. Mainly plays the role of beautification and decoration. About 80% of plastic products are made into final products after coloring.

7. Lubricants

Lubricant is a substance added to improve the demoulding property of plastic during heating molding and improve the surface smoothness of products. Commonly used lubricants are: stearic acid and its salts, paraffin wax, synthetic wax, etc.

8. Reinforcing materials and fillers

In many plastics, reinforcing materials and fillers account for a considerable proportion, especially reinforcing plastics and calcium-plastic materials. Main uses: in order to improve the strength and rigidity of plastic products, various fiber materials or inorganic substances are generally added. The most commonly used reinforcing materials are: glass fiber, asbestos, polystyrene, carbon black, silicate, calcium carbonate, metal oxide and so on.