As we all know, plastic renewable materials are different from the new material, there are often more defects, such as processing performance, mechanical properties, appearance color, aging resistance, etc., resulting in the impact of plastic renewable materials applications.In order to minimize the renewable materials Of the defects, often need to add plastic additives to improve.
1, the role of plastic additives
Plastic additives can effectively improve the processing of renewable materials processing performance and improve production efficiency; and can improve the physical and mechanical properties of recycled materials products and the use of performance, increase its value and service life, to achieve the purpose of high value of renewable materials.
A wide range of plastic additives, play a different role, can refer to the following table to understand:
2, the requirements of additives
Because plastic processing and products are affected by many factors, so the choice of additives will be very high, mainly in the following points:
① should be added with the synthetic resin has good compatibility, long-term stability, uniform dispersion in the resin;
② Synergies. To try to use each other to promote the function of plastic additives;
③ Durability is good. No dialysis, will not send, do not migrate or be extracted by water and liquid substances;
④ suitable for the use of products requirements;
⑤ adaptability to processing conditions is better;
⑥ decentralized, can be easily dispersed in the process of forming uniform.
The above points to meet the requirements of most of the renewable materials on the additives, plastic additives to achieve these points will play an efficient role in the performance of recycled plastics to be the greatest improvement.
3, several commonly used plastic additives
1. Characteristics of additives
The main function of these additives is to give certain characteristics of plastic products, such as physical and mechanical properties, flexibility, flame retardant and so on.
① plasticizer
Plasticizers can reduce the plastic's melting temperature, viscosity and hardness, increase plastic flow and product flexibility and cold resistance, thereby improving the processing and performance of plastics.
Plasticizer is mainly used in PVC, cellulose derivatives, synthetic rubber and nylon and other plastics, plasticizers are not required for all plastics, of which about 80% of the plasticizer for PVC.
② filler
Is to add an inert plastic materials, the purpose is to increase the quality and reduce costs, etc. Fillers can also improve the processing performance of plastics and some of the performance, such as increased strength, heat resistance and corrosion resistance.
Fillers are generally powdered material, the main varieties of calcium carbonate, talc, kaolin, wollastonite, mica and wood flour, commonly used in PVC, polyolefin and ABS resin.
③ enhancer
Reinforcing agent can significantly improve the strength of recycled products, the vast majority of high-strength, fibrous inert material, such as glass fiber, carbon fiber, asbestos, etc., the largest amount of glass fiber.
Enhancers are now widely used in PVC, PP, PE and nylon and other plastics.
④ colorants and optical brighteners
Coloring agent is mainly to give the plastic color, making the product more beautiful.Fluorescent brighteners can effectively improve the appearance of recycled plastic products performance, and can be used with the colorant to make products more beautiful colors.
⑤ flame retardant
Flame Retardant is a kind of additive that can stop or delay the burning of plastic.It can be divided into additive flame retardants and reactive flame retardants two kinds.Adding flame retardants are usually added to the base resin, they And the resin is only a simple physical mixture; the reactive flame retardant is generally a molecule containing a flame retardant element and a reactive group of monomers, such as halogenated anhydride, halogenated bisphenol and phosphorus-containing polyol, due to Reactive, can be chemically bonded to the molecular chain of the resin, as part of the plastic resin, the majority of reactive flame retardant structure or synthesis of additional flame retardant monomer.
⑥ impact modifier
Additives that increase the impact strength of plastics are known as impact modifiers, generally elastomers and tough plastics that are mainly used in PVC, PS, PP and some engineering plastics.
⑦ foaming agent
Foaming agent that can produce gas, plastic products to produce foam or voids of the material, divided into physical foaming agent and chemical foaming agent.Physical foaming agents generally rely on their own physical state changes in the release of gas, mostly volatile Liquid substances, chlorofluorocarbons (such as freons), lower alkanes (such as pentane), and compressed gases are representative of physical blowing agents that are based on the gas released by chemical decomposition. Commonly used Hydrazine is mostly derivatives, of which the most important is azodicarbonamide, can be used for PVC, PE, PS, PP, ABS and other plastics.
Stabilizer
The main function of stabilizers is to retard or stop the degradation of plastics under the influence of physical (heat, light) and chemical (oxygen, microorganism) factors, mainly including heat stabilizers, light stabilizers and antioxidants.
① heat stabilizer
Thermal stabilizers can delay or avoid plastic damage and further degradation due to thermal effects.Usually not specified, the thermal stabilizer specifically refers to the stabilizer used in the processing of polyvinyl chloride and vinyl chloride copolymer.PVC and vinyl chloride copolymer Belong to the heat-sensitive resin, they are easy to release hydrogen chloride during thermal processing, and then lead to thermal aging degradation reaction.Industrial widely used heat stabilizer varieties generally include salt-based lead salts, metal soaps, organic tin, organic antimony Class and other main stabilizers and epoxy compounds, phosphites, polyols, diketones and other organic auxiliary stabilizers.
② light stabilizer
Light stabilizers mainly inhibit or reduce the photodegradation of plastics to improve the weatherability of plastic products.Ultraviolet rays in sunlight have a great effect on the destruction of plastics and besides, the impurities or chromophores in the polymers can also promote the photodegradation of the polymers.
Light stabilizer is mainly used for polyolefin, followed by rubber modified PS, PVC, PU and so on.
③ antioxidants
Antioxidants can retard or inhibit the oxidative degradation of plastics.Antioxidants are the most important types of plastic stabilizers, and almost all polymer resins are involved in the application of antioxidants.
Generally divided into the main antioxidant and secondary antioxidants. The main antioxidant to capture the polymer peroxyl radical as the main function; auxiliary antioxidants have the role of decomposition of polymer peroxo compounds, also known as 'peroxide decomposition agent' .
3. Processing additives
Processing additives plastic renewable materials can be easily processed when forming or improve the molding efficiency, the main release agent, lubricant and so on.
① lubricant
Lubricant can reduce the viscosity of the plastic melt or the friction coefficient between the melt and the processing equipment can be divided into two types of internal and external lubricants lubricant can reduce the friction between polymer molecules and reduce the high polymer processing Viscosity and reduce energy consumption; external lubricant is to reduce the polymer and processing equipment between the friction or adhesion, usually external lubricant and polymer incompatibility.
② release agent
Similar to an external lubricant, a thin layer of high efficient release agent is formed between the article and the mold to allow the article to self-emerge from the mold.
4, the development prospects of plastic additives
With the development of plastic products industry, plastic additives as an integral part of plastic engineering, engineering plastics, high performance and the key ingredients to achieve functionalization of modified, plastic additives industry is also large-scale, intensive The development of the direction of plastic processing additives will continue to expand the application areas, product varieties will be towards efficient, multi-functional, complex and special-purpose development of high-performance green, environmentally friendly, non-toxic and efficient plastic additives R & D and production will be Become the main direction of the development of China's plastic additives industry in the future.