Polyvinyl acetate, packaging applications

Butyl benzyl phthalate is a plasticizer added to polymers to give flexibility and softness. It is used extensively in polyvinyl chloride and in cellulose plastics, polyvinyl acetate, polysulfides, and polyurethane. Also used in flexographic inks for food packaging applications and acrylic coatings, profile extrusions, slush moulding, film and sheeting, coated fabrics, floor and wall coverings, vinyl foams and plastisols for car sealants. 

This group covers polyvinyl chloride (PVC), polyvinylidene chloride (PVdC), polyvinyl acetate and polyvinyl alcohol, each of which has packaging applications. 

The major plastic resins used in packaging are high-density polyethylene, low-density and Unear low-density polyethylene, polyethylene terephthalate, polypropylene, polystyrene, and polyvinyl chloride. A variety of plastics are used in lesser quantities nylons or polyamides, polycarbonate, polyethylene naphthalate, polyvinyhdene chloride, ethylene vinyl alcohol, polyvinyl alcohol, polyvinyl acetate, polyacrylonitrile, and more. In many applications, copolymers... 

Polyvinyl alcohol is produced by hydrolysis of polyvinyl acetate, since the vinyl alcohol monomer is unstable. The degree of solubility can be controlled by modifying the extent of hydrolysis and the molecular weight of the polymer. Films can be produced which are readily soluble in water of any temperature or soluble in hot water only. Applications include hospital laundry bags and soluble pouches for chemicals and detergents. Most applications require the pouch to be contained in an outer barrier package to prevent moisture from reaching the material prematurely. 

Since polyvinyl acetate is a stiff material, the need for more flexible versions became apparent early in the development of the industiy. The adhering of plastic films to paper and the bonding of resin-coated paperboard in packaging applications are two examples of this need for greater flexibility. 

Water-base adhesives are made of materials that can be dissolved or dispersed in water. Both natural (cellulosic, dextrin, starch) and synthetic (phenol formaldehyde, polyvinyl acetate, styrene-butadiene rubber, nitrile rubber) polymer materials are used in manufacturing water-base adhesives. Their primary application is in packaging, with a much smaller percentage usage in construction. Their share of the market, however, has been increasing due to health concerns associated with some of the solvents used in organic-solvent adhesives. 

While the polyvinyl acetate-based emulsions have multiple applications (office glues, wood glues, packaging industry, etc.), the acrylic emulsions are used mainly for the production of autoadhesive films and tapes or for other labels (see PSAs part) their main value therefore lies in the large variety of formulations accessible (using variable composition copolymers) and in the good tolerance they demonstrate toward the plasticizers present in certain substrates (bonding of polyvinylchloride films for example). 

SAN competes with polystyrene, cellulose acetate, and polymethyl methacrylate. Applications for SAN include injection-molded parts for medical devices, polyvinyl chloride (PVC) tubing connectors, dishwasher-safe products, and refrigerator shelving. Other apphcations include packaging for the pharmaceutical and cosmetics markets, automotive equipment, and industrial uses. 

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