Ethylene vinyl acetate copolymer, Ethylene-vinyl acetate latex, ETHYLENE-VINYL ACETATE MOLDING RESIN, ETHYLENE-VINYL ACETATE RESIN,  VAE, VAP, EVA,  24937-78-8

Ethylene vinyl acetate copolymer, Ethylene-vinyl acetate latex, ETHYLENE-VINYL ACETATE MOLDING RESIN, ETHYLENE-VINYL ACETATE RESIN,  VAE, VAP, EVA,  24937-78-8

Ethylene|vinyl acetate copolymer

CAS: 24937-78-8

Molecular Formula: C18H30O6X2

Names and Identifiers

Physico-chemical Properties

Risk and Safety

Hazard Symbols	Xn - Harmful
Risk Codes	40 - Limited evidence of a carcinogenic effect
Safety Description	S24/25 - Avoid contact with skin and eyes. S36/37 - Wear suitable protective clothing and gloves.
WGK Germany	1
RTECS	000000041485
HS Code	3905290000

Upstream Downstream Industry

Nature

• EVA is a random copolymer of ethylene and vinyl acetate. Due to the introduction of the short chain formed by the polar acetic acid group in the ethylene chain, the original crystalline state is changed, so that EVA is more flexible and elastic than polyethylene.
• the properties of EVA resin are strongly related to the content of vinyl acetate and the melt flow rate. When MFR is constant, with the increase of vinyl acetate content, its elasticity, flexibility, compatibility and transparency are improved, and the crystallinity is decreased, increased rigidity, wear resistance and electrical insulation properties. If the content of vinyl acetate is constant, when MFR increases, the softening point decreases, the workability and surface gloss are improved, but the mechanical strength decreases; On the contrary, with the decrease of MFR, the molecular weight increases, impact properties and stress cracking resistance were improved.
• EVA is often blended with other polymers as a modifier because EVA has good flexibility, toughness, stress crack resistance and adhesion properties. The blends of polyethylene and ethylene vinyl acetate copolymer (EVA) have been widely used because of their excellent flexibility, processability, good air permeability and printability.
• the blending amount of polyethylene and EVA blends with EVA, the content of VAc in EVA, the molecular weight of EVA, blend preparation and processing conditions and many other factors change and show different properties.
• The effect of VAc content in
• EVA is extremely significant. When the content of VAc in EVA is low (6.6%), the amount of EVA has no effect on the crystallinity, that is, the density of the blend increases with the increase of EVA content, especially when the EVA content reaches 25%, the increase is faster. EVA containing more VAc has a great effect on the modification of PE, and both the crystallinity and density have a sharp change, increasing VAc content in EVA also leads to a rapid increase in elongation of PE/EVA blends. The effect of modification by increasing the proportion of EVA in the PE/EVA is generally similar to the effect of increasing the VAc content in the EVA.
• EVA can modify the impact properties and environmental stress cracking resistance of HDPE. This is because the relatively long chain branches of EVA molecules cannot enter the closely packed crystal lattice, and the amorphous region between platelets is strengthened, so that toughness and environmental stress crack resistance are improved. EVA is also commonly used to improve the compatibility of HDPE and other polymers, such as HDPE/ LDPE or HDPE/ PP blends after adding EVA, due to the improved compatibility between the two, thus, the impact toughness of HDPE is increased. The incorporation of EVA into HDPE can be used as a flexible material for the manufacture of foam plastics.

Preparation Method

An ethylene-vinyl acetate copolymer is prepared by copolymerization of ethylene and vinyl acetate. EVA obtained by copolymerization of different proportions of monomers has different VAc contents and uses. The production methods of ethylene-vinyl acetate copolymer mainly include high pressure method, solution method and emulsion method. At present, the most widely used method is the high pressure method.

1. high pressure method the high pressure method bulk copolymerization process is similar to the production of LDPE. The copolymerization process may employ an autoclave reactor or a tubular reactor. In general, the pot method is more suitable for the production of EVA, the production process of this method is similar to the high pressure method of low density polyethylene, the initiator is also the same. The main difference is the need for additional vinyl acetate monomer supply system and separation and recovery system. The specific preparation method is ethylene, vinyl acetate, initiator and molecular weight regulator, according to a certain ratio into the high pressure reactor, at 200~220 ℃ and 14. 70 to 15. The polymerization reaction was carried out at 68MPA, that is, different grades of copolymers with vinyl acetate content of 10% to 50% (controlled as needed) and molecular weight of 50,000 to 500,000 were obtained. After separation, purification, extrusion granulation and drying to obtain granular product.
2. solution method an ethylene-vinyl acetate copolymer having a medium content can be produced by a high pressure method, but most of them are produced by a solution polymerization method under a medium pressure. Solution method is the ethylene and VAc in the chain transfer does not produce tert-butyl alcohol, aliphatic hydrocarbons and benzene as solvent, with peroxide, azo compounds as initiator, in 5~7MPa, the solution polymerization is carried out at a temperature of from 30 to 150 ° C., and the VAc content of the resulting copolymer can be varied within considerable limits, generally above 35%.
3. in contrast to bulk polymerization, emulsion polymerization is a method for preparing EVA products having a high VAc content, and the VAc content is 70% to 90%. The emulsion method is to add VAc and initiator K2 S2 0s or (NH4)2 S2 0A to the prepared emulsion medium (the stabilizer is added to the water medium, the copolymer emulsion with a VAc content of 70% to 90% can be obtained by adding ethylene to the emulsifier and polymerizing under the conditions of 1 to 10 MPa below 95 °c.

Use

• EVA resin has a wide range of applications, in which the production process of EVA has an impact on the performance and use of the product. The content of VAc in EVA resin and the different uses of MFR are also different, EVA with low VAc content is similar to LDPE, which is soft and has good impact strength. It is suitable for manufacturing heavy load packaging and composite materials. VAc content of 10% ~ 20% of EVA has good transparency, should be made of agricultural film and shrink packaging film. EVA with more VAc content can be used as adhesive, coating and coating, and can also be made into EVA foam, electrical appliances, cable insulation and daily necessities. It can also be used for polymer modification to improve the flexibility and rigidity of plastics. The cold flow characteristics can be improved by adding EVA with a low degree of polymerization to the fuel oil. In other applications, the copolymers are made into finished products without or with very small amounts of additives or modifiers.
• The main uses of EVA resin are Adhesives, blow molding, wire and cable manufacturing, film products, foam molded products, extrusion and co-extrusion, lamination, hot melt and injection molded products. EVA is also used in the modification of polymers to improve flexibility and rigidity, while low degree of polymerization EVA is added to fuel oils to improve their cold flow characteristics.

1. thin film film is one of the most important uses of EVA. The VAc content of the film grade EVA resin is generally in the range of 126-15%, and the maximum is not more than 20%. Because the content of VAc is too high, the resin viscosity is large, it is not suitable to blow film. EVA resin with 1 ~ 6-s% VAc content has moderate toughness and high transparency, which is suitable for making films and heavy packaging materials. It can be used as a single-layer transparent film. VAc improves the Heat sealing performance of the film, improves the gloss of the film, and reduces the haze. EVA resin with VAc content of 5%~ 7.5% is used for the ice bag film, VAc can prevent the low temperature embrittlement of the film, and make the ice bag keep flexible in the cold and hot environment of pressing. EVA with VAc content of 10% ~ 20% can be used to produce a variety of films for different purposes. The film has high transparency, good impact toughness, good thermal stability, low air permeability, low shrinkage at low temperature, good printability, physiological harmless and other advantages. Film for packaging is the largest market for EVA. EVA resin with VAc content of 10% ~ 12% and LLDPE resin are co-extruded to produce stretched film (EVA/ LLDPE/ EVA), which can replace the shrink film for container packaging and disposable strapping, the EVA layer has excellent adhesive properties. EVA resin and barrier resin PVDC (polyvinylidene chloride) co-extruded film with VAc content of 9%~ 15% are used for packaging of fresh meat, processed beef and poultry. The role of the EVA layer is to protect the Heat sealing strength and heat shrinkage of the fresh meat bag. Compared with LDPE, EVA has a lower melting point; Compared with LL-DPE, its shrinkage is more uniform. The EVA copolymer is therefore the best choice material for this application. With a VAc content of 15% to 18%, EVA films can also be used as hot-melt layers in co-extruded films and for blending with homopolymers. EVA applications belonging to the scope of the protection film also include extrusion adhesive on polyester, celerol and PP film used as cheese wrapping paper; EVA and gold-plated polyester film co-extrusion or lamination for the inside of the box bag instead of tinplate cans; medical films and other applications with strict requirements.
2. adhesive and coating Hot Melt Adhesive is one of the most important applications of EVA, which is characterized by good mechanical properties and mechanical stability, high viscosity, particle size can be controlled, there is a good balance between creep resistance and heat sealing, good wet viscosity and fast curing speed, and special adhesion to difficult-to-bond film substrates.
3. molded and extruded articles EVA copolymers having a VAc content of 9 to 18% are generally used for molded and extruded articles, which have the advantages of flexibility and toughness. The EVA can be extruded into highly transparent hoses and rigid tubes for transfusion, compression of blood, delivery of beverages and mortar for construction, and hoses for dust collection and water supply systems.
4. foam plastic EVA having a VAc content of 12% to 16% produces a high-magnification, independent bubble-type foam plastic. This kind of foam plastic has thermal insulation, thermal insulation, shock, compression deformation is small, good elasticity, good weather resistance and has the secondary processing, can be used in industry, construction industry, aquaculture, as thermal insulation, shock, packaging materials. At present, it has been used for ship lifesaving devices, locomotive cars, etc., and has also been used in building insulation. In the footwear industry, EVA with a VAc content of 10% to 20% can be used alone as the main material, or can be used in combination with LDPE, NR, BR, EPDM, CPE (chlorinated polyethylene) to produce a microporous shoe sole.
5. mixed, composite EVA copolymer can withstand high doses of filler, can be well blended with different organic or inorganic compounds, it is formulated as a composite material for various purposes or as a carrier for a masterbatch, so that it has a wider range of uses. The main use of EVA composite material is as wire and cable. In the EVA, a large amount of superconductor and electrostatic dispersion of carbon black, flame retardants to inhibit the combustion of insulators and other fillers and auxiliaries are added. And after steam and chemical vulcanization process or radiation treatment, can be made of insulation protection foam or sheath. When EVA is used as the carrier of the color masterbatch, the addition amount of the dye and the auxiliary agent (ultraviolet stabilizer) can be as high as 50% to 80%. The capacity of EVA to withstand the amount of additive is proportional to the VAc content of the resin. With an increase in the VAc content, the absorption capacity of the additive is correspondingly increased, and thus a color masterbatch with a high dosage of additive can be obtained. EVA is also an excellent modifier, which can be blended with PE, PP and PVC to prepare a series of plastic modified products with a wide range of applications. The addition of EVA improves the flexibility, toughness, stress crack resistance and adhesion properties of the plastic base material.
6. petroleum crude oil and oil additives EVA with high VAc content can greatly reduce the freezing point of fuel when used as an additive for petroleum products. EVA can be used as oil additives such as paraffin inhibitor and fluidity improver. It can reduce the freezing point of crude oil and improve its low temperature fluidity.
7. other aspects one of the latest uses of EVA is for foundry production and powder metallurgy. When EVA is used as a veneers material for the inner surface of a casting mold, the sand can be completely cured without the addition of an adhesive, and the casting surface is smooth and easy to process. In the manufacture of powder metallurgy, the alloy powder and EVA adhesive are mixed under vacuum or reduced pressure, which can improve the interface affinity of the alloy and improve the free forming degree, so as to obtain a pinhole-free powder metallurgy product. The use of EVA as a base material is a fire-retardant low-smoke resin, etc. In high-tech application materials, EVA can also be used as a base resin for conductive materials, for heating bodies, conductive films, elastic electrodes and computer connectors.

Safety

The Inner packaging of the product is polyethylene film bag, the outer packaging is polypropylene woven bag, and the net weight of each bag is 25kg. During storage and transportation, iron hooks should be kept dry, clean and well-ventilated in the warehouse or compartment.

Molding Process

1. injection molding may be performed using injection equipment generally used for PE or PP. Since EVA has elasticity, it can be made into a rubber-like product without undergoing a vulcanization process, and coloring is easy and the product is bright in color. The lower limit of the molding temperature is to maintain a certain fluidity as the standard, and the upper limit temperature is to prevent the thermal decomposition of EVA. Its thermal decomposition temperature is about 229~230 deg C, under normal circumstances, the temperature control in 170-200 deg C is appropriate.
2. vacuum molded EVA vacuum molded products are smooth and transparent. However, due to its poor thermal conductivity and low melting point, the cavity mold temperature should be low and the molding cycle should be long. Generally, the mold can be formed by a low-temperature cooling method.
3. a general blow molding apparatus may be used for the blow molding film. Due to the low melting point of EVA, the cooling of the material must be given special consideration. The traction force should be small, otherwise it will cause the opening of the film product is poor, in addition, the addition of slip agent should be considered.
4. foam molding foam molding should pay attention to adjust the amount of foaming agent. The foamed products have the characteristics of elasticity, light weight, toughness and low shrinkage.

Reference Information