EVA film ( ethylene vinyl acetate) is a polyolefin which is received thanks to an interpolymerization of ethylene and a monomer of vinyl acetate. The transparent, flexible and light material which owns cushioning qualities and high elasticity, excellent adhesion to various materials. The film of EVA is applied to various purposes, one of key is potting of elements of solar panels, their protection against atmospheric influence and possible corrosion. Such covering very important for lamination of solar elements and batteries in general. The film of EVA not sticky in a condition of standard temperature, however, under the influence of a hot press, is created a cross-link between all elements therefore, there is a peculiar permanent soldering. Also when heating there is a lamination of silicon links on both sides, providing bilateral leakproofness. The back lining is used for formation of the tail of the panel, and front, usually, produced from silicate glass.
Features of material, production vinyl acetate ethylene
This film produce vinyl acetate ethylene from pitches. She personifies a robust sphere during process of manufacture of triplex, safety and decorative glass which make by method of bezavtoklavny and vacuum lamination. The film of EVA is perfectly linked to the following materials: banner, silk, fabrics, rice paper, sheets, wire, banner grid, sheet polycarbonate. To reach an improbable transparence and a high rate of fortress, a film produce at a temperature of 135-140 º C. Temperature range from −80 °C to +55 °C – during which ethylene vinyl acetate keeps the performance characteristics and qualities. Outwardly the film is identical polyethylene, to the touch – rubber-like. Unlike polyethylene materials, the index of flexibility and durability has 25-30% above. This material is perfectly protected from a possible puncture and negative consequences from bruises, there is also a high rate of slip resistance. In production most often use a film of EVA which incorporates 10-50% of vinyl acetate. Widespread ways of processing of this material is an injection molding and extrusion.
Thanks to existence in the structure of the significant amount of a vinyl, ethylene vinyl acetate rather resistant to influence of high temperatures, ozone, solutions, oils. Copolymers with the low content of acetate are similar according to the characteristics to polyethylene of low density. Compatibility with waxes improves and increases the adhesion qualities of material.
Advantages and shortcomings of a film of EVA
As well as any other material, a film of EVA (ethylene vinyl acetate) has particular advantages and shortcomings which distinguish this version among others.
It is possible to refer the following criteria to advantages of a film of EVA:
• Protection of a covering of solar panels against discolouration and loss of ability to develop energy;
• Longevity of material;
• High rates of fortress on a coupler;
• A transparence of material which promotes a high optichnost and svetopropuskny ability of a film;
• Firmness at a high rate of humidity;
• A high cohesive force of a film with materials;
• Resistance to high temperatures;
• Reliability in use;
• It is less, than other materials, it is sensitive to emergence of bubbles and stratifying;
• More resistant to “sostarivaniye”, excellent service performance throughout the progressive time;
• It is completely compatible to all photo cells of solar system;
• Excellent buffer action;
• High dielektrichnost;
• Sound insulation of a covering;
• Easy-to-work;
• Protects a covering from UF-radiation;
• The acceptable material cost.
It is possible to refer the following criteria to shortcomings of a film of EVA:
• A high rate of an opalescence (turbidity flew down which is noticeable at many spherical lamination);
• Emergence of yellowness is possible after a while;
• Small fortress on shift;
• High sensitivity to low and subzero temperatures which can give to laminations;
• Over time loses the transparence, thereby worsening a photosensitivity of solar elements.
Application
Application of a film of EVA is rather various. This material is used not only for potting and lamination of photo cells of solar panels, but also applied in a set of branches and productions.
The film of EVA (in shape ethylene of vinylacetate glues melts) is often used in the following productions: printing, furniture, shoe etc. On its basis produce: blown and flexible articles, hoses, laying, isomats, shoe soles, toys, the routine and laminated films, the clear and weatherproof films for greenhouses, a covering of paper and a cardboard (container), etc. Copolymer vinyl acetate ethylene is often used in preparation time of compounds with other polymers (rubber, polyethylene, PVC), and also mixes with various additives and excipients.
Thanks to a high rate of depreciation qualities and an elastance, and also a sufficient gigiyenichnost of similar materials, the film of EVA is actively applied in production of orthopedic footwear to children and adult, some types of bandages and accessories for sports, in an orthopedic odontology. Orthopedic products on the basis of this material protect joints and a backbone, completely corresponding to biomechanical processes of driving.
Ethylene-vinyl-acetate copolymer is also widely used in the form of an aqueous dispersion and as a plenkosozdatel in water dispersible paints. After the through cure by an express method, the aqueous dispersion ethylene of vinyl acetate turns on redispergovanny powder which is used in production of dry structural blends.
