Some plastics themselves are pure resins, such as polyethylene, polystyrene, etc., which are called single-component plastics. In addition to synthetic resin, some plastics also contain other auxiliary materials, such as plasticizers, stabilizers, colorants, various fillers, etc., which are called multi-component plastics. Stabilizer
We all know that during the processing, storage and use of plastic products, under the action of light, heat and oxygen, aging phenomena such as fading, embrittlement and cracking will occur. In order to delay and prevent the occurrence of aging, stabilizers must be added. Those mainly used to prevent thermal aging are called heat stabilizers; those mainly used to prevent oxidative aging are called antioxidants; those mainly used to prevent photoaging are called light stabilizers. They are collectively called stabilizers. The most excellent plastic stabilizer today is methyl tin heat stabilizer (181 for short), which is very effective in the calendering, extrusion, injection molding and blow molding of rigid polyethylene (PVC). Because of its high safety, it is especially used in 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 plastics. Heat stabilizers. It is widely used in the United States, Europe, and Japan. In recent years, 181 methyl tin heat stabilizer has begun to be widely used in my country.
Plastic additives
Plastic additives The main purpose of adding additives to plastics is to improve processing performance, increase efficiency and reduce costs. Additives account for a small proportion of plastic materials, but they have a great impact on the quality of plastic products. Different types of plastics require different types and amounts of additives due to different molding processing methods and usage conditions. The main additives include the following categories:
Plasticizer
Plasticizers can increase the softness, extensibility, and plasticity of plastics, reduce the flow temperature and hardness of plastics, and are beneficial to the molding of plastic products. Commonly used ones include phthalates, sebacates, chlorinated paraffins, etc.
Flame retardant
Additives that can improve the flame resistance of plastics are called flame retardants. Most plastics containing flame retardants are self-extinguishing or slow down their burning rate. Commonly used flame retardants include antimony oxide, aluminum and boron compounds, halides and phosphates, tetrachlorophthalic anhydride, tetrachlorophthalic anhydride, etc.
Lubricant
Lubricants are substances added to improve the mold release properties of plastics during heat molding and improve the surface finish of products. Commonly used lubricants include: stearic acid and its salts, paraffin wax, synthetic wax, etc.
Reinforcement materials and fillers
In many plastics, reinforced materials and fillers account for 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, various fiber materials or inorganic substances are generally added. The most commonly used reinforcing materials are: glass fiber, asbestos, quartz, carbon black, silicate, calcium carbonate, metal oxide, etc.
Antistatic agent
Antistatic agents play a role in eliminating or reducing static electricity generated on the surface of plastic products. Most antistatic agents are electrolytes. Their compatibility with synthetic resins is limited, so they can migrate to the surface of the plastic to absorb moisture and eliminate static electricity.
Foaming agent
Plastic foaming agent is a low-molecular organic substance that can be vaporized at a certain temperature, such as dichlorodifluoromethane; or it can decompose and release gas when heated.body of organic compounds. These gases remain in the plastic matrix to form foam plastics with many fine foam structures. Commonly used ones include azo compounds, nitroso compounds, etc.
Coloring agent
Colors are used to color plastics. Mainly used for beautification and modification. About 80% of plastic products are colored to make final products.
