We all know that plastic products in the process of processing, storage and use, under the action of light, heat, oxygen, will occur fading, embrittlement, cracking aging phenomenon.In order to delay and prevent aging, stabilizers must be added.Mainly used to prevent thermal aging, called thermal stabilizer;Mainly used to prevent oxidative aging, called antioxidant;Mainly used to prevent light aging, called light stabilizers, they are collectively known as stabilizers.Today's excellent plastic stabilizer is methyl tin heat stabilizer (181 for short), which is very effective for the calendering, extrusion, injection and blow molding of rigid polyethylene (PVC).Due to its high safety, it is especially used in food packaging and high definition of rigid polyethylene products, at the same time, it is also widely used in plastic doors and Windows, water pipes, decorative materials, to replace other highly toxic plastic heat stabilizer.It is widely used in the United States, Europe and Japan.In recent years, 181 methyl tin heat stabilizer has been widely used in China.
The purpose of adding additives to plastics is to improve the processing performance, improve the efficiency and reduce the cost.The proportion of additives in plastic materials is small, but the quality of plastic products has a great impact.Different types of plastics, due to the different processing methods and use conditions, the type and dosage of additives required are also different.The main additives are as follows:
Plasticizer can increase plastic softness, extensibility, plasticity, reduce plastic flow temperature and hardness, is conducive to the molding of plastic products.Commonly used are phthalates, sebacic acid esters, chlorinated paraffins, etc.
Additives that improve the flame resistance of plastics are called flame retardants.Most plastics containing flame retardants have self-extinguishing properties or slow burning rate.The commonly used flame retardants include antimony oxide, aluminum and boron compounds, halides and phosphates, tetrachlorophenylphthalic anhydride, tetraphenylphthalic anhydride, etc.
Lubricants are added to improve the demoulding and surface finish of plastics during heating molding.Commonly used lubricants are: stearic acid and its salts, paraffin, synthetic wax, etc.
Reinforcement and packing
In many plastics, reinforced materials and fillers occupy a considerable proportion, especially reinforced plastics and calcium plastic materials.The main purpose is: in order to improve the strength and rigidity of plastic products, generally add a variety of fiber materials or inorganic.* commonly used reinforcement materials are: glass fiber, asbestos, quartz, carbon black, silicate, calcium carbonate, metal oxide, etc.
Antistatic agent can eliminate or reduce the static electricity on the surface of plastic products.Antistatic agents are mostly electrolytes, which have limited solubility with synthetic resins, which can be transferred to the plastic surface to absorb moisture and eliminate static electricity.
Plastic foaming agent is a low molecular organic matter, such as dichlorodifluoromethane, which can be vaporized at a certain temperature.Or organic compounds that decompose gases when heated.These gases are left in the plastic matrix to form a foam plastic with many fine foam structures.Azo compounds and nitroso compounds are commonly used.
Colouring agents are used in the coloring of plastics.Mainly plays the beautification, the modification function.About 80% of plastic products are finished by coloring.