EVA-ethylene-vinyl acetate copolymer physical properties
English abbreviation: EVA
Molecular formula: (C2H4) x. (C4H6O2) y
Molecular weight: 342.43
Relative molecular mass: 2000 (average)
CAS No .: 24937-78-81
Appearance: white particles
Melting point: 75 ° C Boiling point: 170.6 ° C
Relative density: 0.948g / mL (25 ℃)
Flash point: 260 ℃
Solubility: toluene, THF, and MEK: soluble
The detailed distinction is as follows:
Ethylene acetic acid content
10% softer than polyethylene, good impact resistance, used as packaging bags and films, injection molded parts, cable coatings, toys, etc.
10% -20% good transparency, cold resistance and stress cracking resistance, used to make agricultural films, medical appliances, etc.
20% -40% has good adhesion, used as hot melt adhesives, coatings, etc.
45% -55% good elasticity, used as special rubber, good compatibility with other rubbers, good processability, peroxide vulcanization, comparable to vulcanized rubber
65% ～ 95% is emulsion, which can be used as adhesive for fiber, paper, etc.
The performance of EVA has a great relationship with the content of vinyl acetate (VA). When the content of VA increases, its resilience, flexibility, adhesion, transparency, solubility, stress crack resistance and impact performance will all Increase; when the content of VA decreases, the rigidity, wear resistance and electrical insulation of EVA will increase. Generally speaking, when the VA content is in the range of 10% to 20%, it is a plastic material, and when the VA content exceeds 30%, it is an elastic material.
EVA resin is an ethylene-vinyl acetate copolymer, generally the content of vinyl acetate (VA) is 5% -40%. Compared with polyethylene, EVA has been widely used in foam shoes due to the introduction of vinyl acetate monomer in the molecular chain, thereby reducing high crystallinity, improving flexibility, impact resistance, filler compatibility and heat sealing performance. Materials, functional shed films, packaging films, hot melt adhesives, wires and cables, toys and other fields. In general, the performance of EVA resin mainly depends on the content of vinyl acetate on the molecular chain.
Foam shoe material
Shoe material is the most important application field of EVA resin in China. In the EVA resin used in shoe materials, the vinyl acetate content is generally 15% to 22%. Because EVA resin blended foam products have the properties of softness, good elasticity, chemical resistance, etc., they are widely used in the soles and interior materials of middle and high-end travel shoes, hiking shoes, slippers, sandals. In addition, this material is also used in the field of sound insulation board, gymnastic mat and sealing material.
Film
The main purpose of EVA film is to produce functional shed film. The functional shed film has high weather resistance, anti-fog droplets and thermal insulation performance. Since polyethylene does not have polarity, even if a certain amount of anti-fog droplets is added, its anti-fog droplet performance can only be maintained for about 2 months; and The shed film made by adding a certain amount of EVA resin not only has a high light transmittance, but also has a large improvement in anti-fog droplet performance, which can generally exceed 4 months. In addition, EVA can also be used to produce packaging films, medical films, laminated films, cast films, etc.
Wire and Cable
With the continuous development of computer and network engineering, for the safety of the computer room, people are increasingly using halogen-free flame retardant cables and silane cross-linked cables. Because EVA resin has good filler inclusion and crosslinkability, it is used more in halogen-free flame retardant cables, semiconductor shielded cables and two-step silane crosslinked cables. In addition, EVA resin is also used to make some special cable jackets. The EVA resin used in wire and cable generally has a vinyl acetate content of 12% to 24%.
Toy
EVA resin also has many applications in toys, such as baby wheels and seat cushions.
Hot melt adhesive
The hot melt adhesive with EVA resin as the main component, because it does not contain solvents, does not pollute the environment and has high safety, is very suitable for automated assembly line production, so it is widely used in book wireless binding, furniture edge banding, automobiles and household appliances Assembly, shoemaking, carpet coating and metal anti-corrosion coating.
Manufacture of refrigerator ducts, gas pipes, civil construction plates, containers and daily necessities. It can also be used for packaging films, gaskets, medical equipment, and can also be used as hot-melt adhesives and cable insulation.
EVA emulsion
EVA emulsion is the abbreviation of vinyl acetate-ethylene copolymer emulsion. It is a polymer emulsion made by copolymerizing vinyl acetate and ethylene monomer as basic raw materials and other auxiliary materials by emulsion polymerization method.
EVA emulsion is mainly used in adhesives, coatings, cement modifiers and paper processing, and has many excellent properties.
EVA emulsion has permanent flexibility. EVA emulsion can be regarded as an internal plasticized product of polyvinyl acetate emulsion. Due to the introduction of ethylene molecular chain in the polyvinyl acetate molecule, the acetyl group has a discontinuity, which increases the freedom of rotation of the polymer chain and prevents space Small, the polymer backbone becomes soft, and plasticizer migration does not occur, ensuring that the product is permanently soft.
EVA emulsion has good acid and alkali resistance. EVA emulsion can maintain stable performance in the presence of weak acid and weak base, so no matter it is mixed with weak acid or weak base, it will not break the emulsion, and the product has a wide range of applications.
EVA emulsion can resist ultraviolet aging. Since the EVA emulsion uses ethylene as the internal plasticizer of the copolymer, the EVA polymer has internal plasticity, and the plasticizer will not migrate, thereby avoiding the aging of the polymer performance. Therefore, not only EVA milk
EVA-ethylene-vinyl acetate copolymer foam shoe material
The liquid has good stability to ultraviolet rays, that is, it can also maintain this feature after the EVA emulsion is formed into a film.
EVA emulsion has good compatibility. EVA emulsion can be mixed with most additives, such as dispersants, wetting agents, antifreeze agents, defoamers, preservatives, flame retardants, etc., so it can meet various needs; EVA emulsion can be mixed with many pigments and fillers, No coagulation will occur; EVA emulsion can be directly mixed with many low molecular and high molecular water-soluble polymers, such as polyvinyl alcohol aqueous solution, polyethylene glycol aqueous solution, starch or modified starch gelatinization solution, sodium polyacrylate aqueous solution, Polymaleic acid aqueous solution, polyoxyethylene aqueous solution, urea formaldehyde, phenolic aqueous solution, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose aqueous solution, etc .; EVA emulsion can be directly mixed with many other polymer polymerization emulsions, such as poly Vinyl acetate emulsion, polyacrylate emulsion; EVA emulsion can be directly mixed with aldehydes, esters, ketones, organic acids, polyols, higher alcohols, halogenated hydrocarbons, aromatic hydrocarbons, such as formaldehyde, glyoxal, phthalic acid diacid Butyl ester, dioctyl phthalate, acetic acid, carbon tetrachloride, chloroform, benzene, toluene, xylene, octanol, ethylene glycol, glycerin, ethyl acetate, butyl acetate, etc.
EVA emulsion has good film-forming properties. Emulsion adhesives can only form a transparent film at a certain temperature, which is called the minimum film-forming temperature. The minimum film-forming temperature of EVA is generally lower than 5 ℃, so it can form a film very well, and the film has a good barrier to water droplets.
EVA emulsion has good adhesion. It has good adhesion to fiber, wood, paper, plastic film, aluminum foil, cement, ceramics and other products.
According to the water resistance of EVA emulsion polymer, it can be divided into two categories: general purpose and waterproof. EVA polymers of general-purpose products have good rigidity and high adhesion strength, but poor water resistance; EVA polymers of waterproofing products have good flexibility and water resistance, but low bonding strength. According to EVA application performance, copolymer composition and copolymerization of the third monomer type, EVA emulsion can be divided into two categories of viscose and textile. EVA sticky products are mostly used as general-purpose adhesives, and textile adhesives are mostly used as adhesives for textile fibers, but there is no absolute limit between the two.
Because EVA emulsion has many excellent properties, it has a very wide range of applications in practical applications.
EVA emulsion is widely used as the base material of adhesives. EVA emulsion has good mechanical properties, the average particle size of the emulsion particles is small, there is a good balance between creep resistance and heat sealability, good wet viscosity and fast curing speed. EVA emulsion has a wide range of adhesive properties. In addition to bonding wood, leather, fabric, paper, cement, concrete, aluminum foil, galvanized steel plate and other materials, it can also be used as pressure-sensitive adhesive and heat-sealing adhesive. The connected materials such as polyethylene, polypropylene, polyvinyl chloride, polyester and other films have unique adhesiveness.
EVA emulsion can be used as a base material for coatings. Paints made of polyvinyl acetate emulsion, acrylic emulsion, EVA emulsion, styrene-butadiene emulsion, propylbenzene emulsion, vinegar-benzene emulsion, etc. are collectively called latex paints. EVA latex paint can be used as interior and exterior wall coatings, roofing waterproof coatings, fire retardant coatings, and anti-rust coatings. The EVA latex paint film has good foaming resistance, is resistant to aging and is not easy to crack, has good adhesion to various substrates, is safe and non-toxic, and is easy to use. EVA latex paint can be applied not only on wood, masonry and concrete, but also on the surface of metal, glass, paper and fabric. It also has good affinity with paint and can be painted on each other's surface.
EVA emulsion can be used for paper processing. With the development of synthetic polymer technology, many polymer substances play a great role in paper processing, especially some synthetic polymer emulsions are more advantageous in paper processing, EVA emulsion is one of them. EVA emulsion is mainly used for paper impregnation, paper coating and pulp addition in paper processing. It is characterized by being able to polish a variety of papers, increasing the wet and dry strength, toughness and gloss of the paper, improving color stability and reducing ink printing Consumption, improve paper grades. As a pulp additive, various non-asbestos type gaskets can be made. EVA emulsion can also be used in special paper processing, such as making disposable napkins, facial tissues, diapers, sanitary napkins, etc. using dry puffed papermaking.
EVA-ethylene-vinyl acetate copolymer emulsion can be used as cement modifier. Cement is one of the most widely used materials in construction engineering. However, simple cement products have the disadvantages of easy cracking and poor water resistance, impact resistance and acid resistance, which affect the practical effect of cement to a certain extent. Since the 1920s, people have been working on the modification of cement. With the deepening of research, it was found that many synthetic latexes have better effects on cement modification, such as polyvinyl acetate emulsion, acrylic emulsion, styrene and toluene emulsion, EVA emulsion, etc. Among them, EVA emulsion has good water resistance, acid and alkali resistance and weather resistance, and its price is cheaper than similar products. Therefore, it is being widely used in civil engineering as a new material. In recent years, under the consideration of environmental protection, EVA redispersible latex powder has gradually appeared on the market, and gradually replaced the position of EVA emulsion in cement modifier, becoming the main product of the main cement modifier.
