Ethylene-vinyl acetate copolymers laminating

Ethylene vinyl acetate copolymer (EVA) forms a soft, tacky film with good water-vapor barrier but very poor gas-barrier properties. It is widely used as a low temperature initiation and broad-range, heat-sealing medium. The film also serves for lamination to other substrates for heat-sealing purposes. 

Ethylene vinyl acetate copolymers are used as membranes and backings in laminated transdermal drug delivery systems. They can also be incorporated as components in backings in transdermal systems. Ethylene vinyl acetate copolymers have been shown to be an effective matrix and membrane for the controlled delivery of atenolol triprolidine, and furose-mide. The system for the controlled release of atenolol can be further developed using ethylene vinyl acetate copolymers and plasticizers. ... 

Many substrates, including paper, paperboard, cellulose film, fireboard, metal foils, or transparent films are coated with resins by direct extrusion. The resins most commonly used are the polyolefins, such as polyethylene, polypropylene, ionomer, and ethylene-vinyl acetate copolymers. Nylon, PVC, and polyester are used for a lesser extent. Often combinations of these resins and substrates are used to provide a multiplayer structure. [A related technique, called extrusion laminating, involves two or more substrates, such as paper and aluminum foil, combined by using a plastic film, (e.g., polyethylene) as the adhesive and as a moisture barrier.] Coatings are applied in thicknesses of about 0.2-15 nuls, the common average being 0.5-2 mils, and the substrates range in thickness fi om 0.5 to more than 24 mils. 

Over the last four decades there have been a number of attempts to wed the unique benefits of polyurethane adhesives with the benefits of other adhesive systems. These attempts have led to the reporting of a variety of urethane hybrids. Early work focused on simple blends for example, in 1964 Union Carbide blended organic isocyanates with ethylene-vinyl acetate copolymers [66]. These blends were used as an adhesive interlayer in glass laminations, particularly safety glass laminates. Similarly, polylurethane poxy blends for safety glass laminates were reported in 1970 [67]. 

Adhesives are used in tufted carpets to anchor and stabilize the yarns they can also be used to attach a foam backing or a laminated secondary backing. Latices predominate with SBR (cross-linked) being the most widely used EVA latex (see Ethylene-vinyl acetate copolymers) is cheaper but has lower bond strength and is water sensitive. Other adhesives used are PVC plastisols in carpet tiles and hot melts and two-component polyurethanes in top-quality products (because hot melts and polyurethanes are relatively expensive). 

Film laminate adhesives Ethylene-vinyl acetate copolymer Japan 135,860 1979 Mitsubishi Chemical... 

Packaging laminates Ethylene-vinyl acetate copolymer Japan 57,582 1979 Asahi-Dow Ltd. 

Laminates Ethylene-vinyl acetate copolymer Japan 110,282 1979 Nippon Petrochemical... 

Poly(ethyl methacrylate) (PEMA) yields truly compatible blends with poly(vinyl acetate) up to 20% PEMA concentration (133). Synergistic improvement in material properties was observed. Poly(ethylene oxide) forms compatible homogeneous blends with poly(vinyl acetate) (134). The T of the blends and the crystaUizabiUty of the PEO depend on the composition. The miscibility window of poly(vinyl acetate) and its copolymers with alkyl acrylates can be broadened through the incorporation of acryUc acid as a third component (135). A description of compatible and incompatible blends of poly(vinyl acetate) and other copolymers has been compiled (136). Blends of poly(vinyl acetate) copolymers with urethanes can provide improved heat resistance to the product providing reduced creep rates in adhesives used for vinyl laminating (137). 

In this example a polymer laminate film (for packaging) was examined, which was composed of nine layers (see Table 2), by both FTIR imaging and Raman line scan. For the IR measurements thin sections (5 pm) were cut. The central ethylene/vinyl acetate (EVA) copolymer layer is very soft, and holes can be seen in the visible image (Figure 12). 

Films made with barrier polymers, e.g., polyamide (PA)/polyethylene (PE) laminates, ethylene vinyl acetate (EVA) copolymer/polyvinyl chloride (PVC)-polyvinylidene chloride (PVDC) copolymer laminates, and ionomer/ PA/EVA laminate films are used for vacuum packaging, particularly products like red meat. 

Ethylene-vinyl acetate (EVA) copolymers. EVA copolymers are given by the structure shown in Fig. 1.27 and find commercial importance in the coating, laminating, and film industries. EVA copolymers typically contain between 10 and 15 mol % vinyl acetate, which provides a bulky, polar pendant group to the ethylene and provides an opportunity to tailor the end properties by optimizing the vinyl acetate content. Very low vinyl-acetate content (approximately 3 mol %) results in a copolymer which is essentially a modified low-density polyethylene, " with an even further reduced regular structure. The resultant copolymer is used as a film due to its flexibility and surface gloss. Vinyl acetate is a... 

Soybean (Glycine soja) meal Vinyl acetate Vinyl acetate/ethylene/vinyl chloride terpolymer Vinyl acrylic copolymer binder, paper coatings/sizing Alginic acid binder, paper laminates Bisphenol A diglycidyl ether binder, paper processing Meroxapol 105 Meroxapol 108 Meroxapol 171 Meroxapol 172 Meroxapol 174 Meroxapol 178 Meroxapol 251 Meroxapol 252 Meroxapol 254 Meroxapol 255 Meroxapol 258 Meroxapol 311 Meroxapol 312 Meroxapol 314 binder, paper sizing... 

Cornelio Clark, P.A., Gardner, S.A., Horwat, D. (1995) Probing the interfacial properties of poly(vinyl acetate-ethylene) copolymer/poly(vinyl chloride) laminations by time-of-flight secondary ion mass spectrometry. J. Vac. Sci. Technol. A, 13,1351-1358. 

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