Polyvinyl acetate pressure-sensitive

Fig 1 Scheme of the screen-printed process a typical thick-film screen consists of a finely woven mesh of stainless steel, nylon or polyester, mounted under tension on a metal frame, normally aluminium. The screen defines the pattern of the printed film and also determines the amount of paste which is deposited. The mesh is coated with a ultraviolet sensitive emulsion (usually a polyvinyl acetate or polyvinyl alcohol sensitized with a dichromate solution) onto which the circuit pattern can be formed photographically. The ink is placed at one side of the screen and a squeegee crosses the screen under pressure, thereby bringing it into contact with the substrate and also forcing the ink through the open areas of the mesh. The required circuit pattern is thus left on the substrate... 

ADHERE-TEX 1510 is a semi-permanent pressure sensitive adhesive which develops outstanding tack when the cast film is dried. The adhesive properties may be modified by dilution with water, thickening, or blending with other polymers such as TEX-WET 1089, a polyvinyl acetate emulsion. 

Some solvent cements and solvent-containing adhesives, such as pressure-sensitive adhesives (PSAs), will collapse thermoplastic foams by dissolving the cell walls. In such cases water-based adhesives based on SBR or polyvinyl acetate, or 100%-solids adhesives are often used (1). 

In the hot-melt type, two principal polymer types are used polyolefin and ethylene co-polymer based and polyester and polyamide type. In the solvent-based type, the most prominent are neoprene (polychloroprene)-based solvent and latex types, and polyvinyl acetate emulsions. For pressure-sensitive adhesives, the most favored are acrylic adhesives and butyl rubber/polyisobutylene types. 

Solvent cements are usually preferable to conventional adhesives for thermoplastic structural foams. Some solvent cements and solvent-containing, pressure-sensitive adhesives will collapse thermoplastic foams. Water-based adhesives based on SBR, polyvinyl acetate, or neoprene are frequently used. Solvent cementing is not effective on polyethylene foams because of their inertness. Recommendations for adhesives for thermoplastic foams are ... 

Acetone and methyl ethyl ketone are components of solvent blends in urethane, nitrile rubber, and neoprene industrial adhesives. Acetone is the primary solvent in resin-type adhesives and pressure sensitive chlorinated rubber adhesives. Methyl isobutyl ketone is a solvent component for nitrile rubber and acrylic adhesives as well as in polyvinyl chloride and polyvinyl chloride-polyvinyl acetate copolymer bonding adhesives. Again, the desired evaporation rate of the adhesive formulation will often determine the ketone selected. 

Some rubbers, acetal resins, and a variety of polyethers are prepared on a commercial scale by cationic polymerization. Vinyl ethers are among the easiest monomers to polymerize by the cationic process. The carbonium ion is readily formed because the pendant oxygen participates in delocalization of the positive charge. When polymerization of isobutyl vinyl ether is carried out at temperatures in the range of — 80°C using boron trifluoride etherate as initiator, isotactic crystalline polymer can be produced. Ethyl and isobutyl ethers produce polyvinyl ethers with low 7 s, and are used in pressure-sensitive adhesives. 

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