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With China Plastic Machinery
With China Plastic Machinery
PEVA is polyethylene-vinyl acetate, which is a mixture of PE and EVA. It has good softness and a little elasticity. The higher the proportion of PE, the more difficult it is to handle the adhesion. It is generally used to produce membranes. The ratio of these two chemical substances can be adjusted to meet different application needs. The higher the content of vinyl acetate (VA content), the higher its transparency, softness and toughness will be.
PE characteristics
PE = Polyethylene, polyethylene, is the simplest macromolecular organic compound and the most widely used macromolecular material in the world today. It is polymerized from ethylene and is divided into high-density polyethylene, medium-density polyethylene and low-density polyethylene according to different densities.
Low-density polyethylene is softer and is mostly polymerized under high pressure; high-density polyethylene has the characteristics of rigidity, hardness and high mechanical strength, and is mostly polymerized under low pressure. High-density polyethylene can be used as containers and pipes, as well as high-frequency electrical insulation materials for radar and television. Low-density (high-pressure) polyethylene is often used in large quantities. Polyethylene is waxy and has a waxy smoothness. When not dyed, low-density polyethylene is transparent, while high-density polyethylene is opaque. Polyethylene is a high polymer chain formed by repeated ¨CCH2¨C units connected by addition reaction and polymerization reaction of ethylene (CH2=CH2). The performance of polyethylene depends on its polymerization method; high-density polyethylene (HDPE) is formed by Ziegler-Natta polymerization under medium pressure (15-30 atmospheres) and organic compound catalysis. The polyethylene molecules polymerized under this condition are linear, and the molecular chain is very long, with a molecular weight of up to hundreds of thousands. If it is free radical polymerization under high pressure (100-300MPa), high temperature (190-210C), and peroxide catalysis, low-density polyethylene (LDPE) is produced, which has a branched structure.
Polyethylene is insoluble in water and has very low water absorption. Even for some chemical solvents, such as toluene and acetic acid, it is only slightly soluble at temperatures above 70¡ãC. However, micro-particle polyethylene can melt or solidify with the change of temperature between 15¡æ and 40¡æ. It melts when the temperature rises and absorbs heat; it solidifies when the temperature drops and releases heat. Because it absorbs very little water, it is not easy to get wet and has insulation properties. Therefore, it is a good building material.
Performance characteristics of EVA
The characteristics of EVA and PEVA are:
1. Biodegradable: It will not harm the environment when discarded or burned.
2. Similar to PVC in price: EVA is more expensive than toxic PVC, but cheaper than PVC without phthalates.
3. Lightweight: The density of EVA ranges from 0.91 to 0.93, while that of PVC is 1.32.
4. No odor: EVA does not contain ammonia or other organic odors.
5. Heavy metal-free: in compliance with relevant international toy regulations (EN-71 Part 3 and ASTM-F963).
6. Phthalate-free: suitable for children's toys and will not produce the risk of plasticizer release.
7. High transparency, softness and toughness: a wide range of applications.
8. Super low temperature resistance (-70C): suitable for icing environments.
9. Water-resistant, salt-resistant and other substances: can be applied in a large number of applications.
10. High heat adhesion: can be firmly attached to nylon, polyester, canvas and other fabrics.
11. Low lamination temperature: can speed up production. Keep stable.
12. Can be screen printed and offset printed: can be used for more fancy products (but must use EVA ink).
(1) Foamed Shoes Shoes are the main application area of EVA resins in China. In EVA resins used in shoes, the vinyl acetate content is generally between 15% and 22%. Since EVA resin blended foam products have the properties of softness, good elasticity, and chemical corrosion resistance, they are widely used in the soles and interior materials of mid-to-high-end tourist shoes, mountaineering shoes, slippers, and sandals. In addition, this material is also used in the fields of sound insulation boards, gymnastics mats, and sealing materials. Shunde and Zhongshan in Guangdong, Jinjiang and Quanzhou in Fujian, and Wenzhou in Zhejiang are the main production bases of China's shoe industry, consuming a large amount of EVA resin products every year. In 1999, China consumed about 150 kt of EVA resin in the fields of foamed shoes and shock absorption.
(2) Films The main use of EVA film is to produce functional greenhouse films. Functional greenhouse films have high weather resistance, anti-fog and thermal insulation properties. Since polyethylene is not polar, even if a certain amount of anti-fog agent is added, its anti-fog performance can only last for about 2 months; while greenhouse films made by adding a certain amount of EVA resin not only have high light transmittance, but also have greatly improved anti-fog performance, which can generally last for more than 4 months. In addition, EVA can also be used to produce packaging films, medical films, laminated films, casting films, etc. In 1999, there were more than 50 companies in China that used EVA resin to process films. In 1999, China produced a total of 800 kt of greenhouse films, including 220 kt of functional greenhouse films, consuming about 30 kt of EVA resin. In addition to the packaging film, medical film and other fields, China consumed a total of 37 kt of EVA resin in the film field.
(3) Wires and cables With the continuous development of computer and network engineering, people are increasingly using halogen-free flame-retardant cables and silane cross-linked cables for the sake of computer room safety. Since EVA resin has good filler tolerance and cross-linking properties, it is widely used in halogen-free flame-retardant cables, semiconductor shielded cables and two-step silane cross-linked cables. In addition, EVA resin is also used to make the sheath of some special cables. The vinyl acetate content of EVA resin used in wires and cables is generally 12% to 24%. In 1999, the wire and cable industry consumed about 6,000 tons of EVA.
(4) Toys EVA resin is also widely used in toys, such as children's wheels and seat cushions. In recent years, China's toy processing industry has developed rapidly, with production concentrated in coastal areas such as Dongguan, Shenzhen, and Shantou, mainly for export and external processing. Among them, the small mushroom sound mat has brought the development of mats to a new height. According to analysis, these manufacturers consume about 5,000 tons of EVA resin each year, and the brands used are basically the same as those used for shoe materials.
(5) Hot melt adhesive Hot melt adhesive with EVA resin as the main component does not contain solvents, does not pollute the environment and is highly safe, making it very suitable for automated assembly line production. Therefore, it is widely used in book binding, furniture edge banding, automobile and household appliance assembly, shoemaking, carpet coating and metal anti-corrosion coating. Hot melt adhesive mainly uses varieties with a vinyl acetate content of 25% to 40%. Although China has products of this brand, it has not been produced for a long time, so all of it is occupied by imported materials. In 1999, China's hot melt adhesive industry consumed an estimated 17 kt of EVA resin.
(6) Other EVA resins are also widely used in inks, luggage, wine bottle caps and other fields. It is estimated that these areas consume no less than 15 kt of EVA resin.
In 2004, Mr. Zhang Guoyuan officially initiated the establishment of PEVA, which was officially registered as a non-profit organization at the Civil Affairs Bureau in June. After its establishment, PEVA has been promoting civic awareness and volunteerism in the local area, and has been promoting the development of "corporate citizenship" awareness.
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