The mechanical properties of the copolymer and its type (thermoplastic or elastomer) are determined by the content of vinyl acetate in the material. The most widespread EVA with 10-50% vinyl acetate content. When the content of this component rises to 100%, polyvinyl acetate (PVAC) is obtained. Due to the large amount of vinyl, ethylene vinyl acetate is highly resistant to various substances and media (for example, solvents, ozone, oils and high temperature). With a low acetate content, the copolymers acquire properties similar to those of low density polyethylene.
Ethylene vinyl acetate is an elastic and light in weight material that surpasses polyethylene in transparency and elasticity at low temperatures, has increased adhesion to various metals and good cushioning properties.
EVA copolymers are used for the production of hot melt adhesives (the content of ethylene vinyl acetate in them is from 19 to 40%), flexible blown products, shoe soles, films for greenhouses and packaging, laminated films, such as paper coatings or cardboard packaging. The ethylene vinyl acetate copolymer is also widely used in the preparation of compounds with other polymers (for example, rubber, PVC or polyethylene, as well as various mixtures with fillers and additives).
The method of its processing depends on the destination of finished products from EVA. For example, in the manufacture of sheets, hoses, films and cable sheaths, the extrusion method is used. Shoe sole, rugs, isomats, toys are made by injection molding, etc. In the form of an aqueous dispersion, this material is used as a film former in water-dispersion paints. The aqueous dispersion, dried by special technology, which is a redispersible powder, has found wide application in the production of dry building mixtures.
Ethylene vinyl acetate has the widest application, and we already wrote about the production of beach shoes and adhesives from it. However, there is another direction in this area of production, which is still not sufficiently developed in our country, but, according to experts, is very popular and promising. It includes the production of ... soft modular coatings (the so-called "soft floor") based on EVA, which are ideal for children's rooms in apartments and houses, as well as in various children's institutions. Such coatings have a number of significant advantages compared to other materials: they are very warm and soft (completely safe for the child), environmentally friendly (especially compared to rubber), do not require complicated care, are odorless and do not evaporate any harmful substances into the air .
As a rule, such a coating is made in the form of tiles of various sizes with dovetail hooks. The most common format is 30 by 30 cm and 1 cm thick. However, the density and size of the tiles can vary over a fairly wide range. Since the soft floor is mounted from separate modules, laying it does not take much time and does not require much experience. If one of the tiles is damaged, it can be easily replaced with a new one without changing the entire floor. EVA-based coating is easy to clean, does not collect dust, is not afraid of moisture and temperature changes. It has good thermal insulation properties (you can walk on it barefoot, you can lie on it and sit on it even in the cold season without additional heating), it does not conduct electric current. Finally, the color scheme of such a coating is very diverse. In addition to plain tiles, it is also possible to make coatings with various patterns, including imitations of a wide variety of surfaces (for example, wood, cork, parquet, etc.), which opens up great scope for interior designers.
However, it is worth recognizing that the coating of ethylene vinyl acetate has its drawbacks. For example, it is not intended for active physical education and sports, or even walking in shoes with hard soles, since under intense load the top layer of the coating wears out quickly. In addition, with frequent wet cleaning, the pattern on the surface of such a coating can soon fade or even be erased. Thus, despite all the claims of manufacturers and sellers of such modular coatings, EVA tiles are not suitable for use in rooms other than children’s. But in the latter case, they are practically indispensable, especially if we are talking about young children who are still bad or don't walk at all.
Modular ethylene vinyl acetate coatings are injection molded. This requires special equipment - piston or screw type injection machines, which have a high degree of mechanization and automation. With the help of injection machines, granular material is dosed, converted into a viscous flow state. Then, measured doses of molten material are injected (injected) into the mold. There it is under pressure until it is completely cured, after which the form opens and the finished product is pushed out. During the processing of thermoplastics, the injection mold is thermostated (while its temperature should not be higher than the glass transition or crystallization temperature). The pressure at which the casting is carried out depends on many parameters: the viscosity of the melt of the material, the design of the mold, the size of the gate system and the molded product. Injection molding at ultrahigh pressures (up to 500 MPa) makes it possible to reduce residual stresses in the material and increase the degree of orientation of crystallizing polymers, which, in turn, contributes to the hardening of the material and provides a more accurate reproduction of the dimensions of parts. The pressure in the mold when it is filled with the polymer melt rises gradually (at the end of holding under pressure it reaches 30-50% of the casting pressure) and is distributed unevenly along the length of the forming cavity due to the high viscosity of the melt and its rapid increase upon cooling or curing.
For the production of modular floor coverings, special lines for the production of EVA products will be required, which include injection machines (equipped with two automatic nozzles, a form clamp and an automatic control system), foaming machines and equipment for applying a pattern and a protective coating to the tiles. All this equipment is automated and can be controlled by 2-3 operators. As a rule, it is most profitable to order such equipment in China, although transportation costs will be quite high, but even with these in mind, it is much more profitable than acquiring a line through intermediaries in our country. The dimensions of the line are about ten meters in length and almost three meters in height. To accommodate it requires a production area of about 120 square meters. meters, not counting the individual areas for a warehouse of finished products, a warehouse of raw materials and household premises for workers.
Ethylene vinyl acetate, various additives and dyes will be required from raw materials. The largest suppliers of EVA are PolimeriEuropa, ExxonMobil, Arkema, Total, Repsol, DuPont (Elvax).
In addition to modular EVA coatings, to increase the profitability of the enterprise (which is about 25%), you can also start manufacturing rubber flooring. They also have a number of undeniable advantages, especially in those places where the coating is constantly exposed to severe stresses. Thick rubber is much more resistant to wear and various, even adverse, climatic conditions than ethylene vinyl acetate. At the same time, it has good cushioning properties, which protects children in the fall, and fire resistance, resistance to water. Moreover, these properties can be significantly improved by adding rubber crumbs to the coating composition in combination with a polymer binder.
Rubber floors can be produced in various forms - in the form of rolls or separate modules (as is the case with EVA coatings). There are even bulk seamless floors, but their manufacture is more complex and expensive. If coatings of ethylene vinyl acetate appeared relatively recently on the Russian market and are still not well known to domestic consumers, then rubber floors are already widespread and are very popular. They also differ in a variety of color schemes, patterns and textures (including imitation of natural stone or lawn grass), provide good sound insulation, and they can be used not only indoors, but also outside it (for example, in children's playgrounds). The rubber coating is practically immune to most external influences (for example, oil, solvents, diluted alkalis and acids), is absolutely undemanding in maintenance (but it is recommended to use means with a wax content for washing and cleaning to increase the wear resistance of the floor).
The profitability of the production of rubber coatings according to the manufacturers themselves reaches 50%. The main raw material for the manufacture of such coatings is crumbs (granules), which, in turn, is obtained as a result of the processing of old car tires. The manufacturing process itself is relatively simple. First, with the help of special equipment, rubber crumb is mixed with a given amount of polyurethane glue and dyes, and then the mixture is pressed, resulting in a beautiful, durable material of various color shades and with an ideally even and moisture-proof surface.
If coatings based on ethylene vinyl acetate have a rather narrow scope and acquire them mainly for the arrangement of children’s and playrooms (and, mainly, not in public but in residential premises due to their low wear resistance), then rubber floor coverings are more universality. They can be sold through construction stores, directly to construction companies, owners of piers, moorings, boats, fitness clubs, pools, water parks, tennis courts, farms (for flooring in rooms where animals are kept). The cost of coating from EVA is from 45 rubles per tile measuring 30 by 30 cm in wholesale and about 1000 rubles per square meter. meter at retail. Rubber floor coverings are sold at a retail price of 1, 500 rubles per square meter. meter.
About 4 million rubles will be required to organize the production of rubber coatings. This amount includes the purchase of equipment, materials, rental of production and storage facilities, wages to employees for the first two months of the enterprise. The organization of the production of modular coatings of vinyl acetate will cost about the same amount - 3.5 -4 million rubles. The most expensive equipment is: one line with delivery, installation and commissioning costs about 2.5 million rubles.
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