Polymers vinyl acetate

Vinyl acetate [108-05-4] (VAc), CH2=CHOOCCH2, the ethenyl ester of acetic acid, is primarily use for the manufacture of poly(vinyl acetate) [9003-20-7] (PVAc) and vinyl acetate copolymers. Poly(vinyl acetate) homo- and copolymers are found as components in coatings, paints and sealants, binders (adhesives, nonwovens, constmction products, and carpet-backing), and miscellaneous uses such as chewing gum and tablet coatings. AppHcations have grown over the years in a number of areas (1 4). 

Vinyl acetate is a colorless, flammable Hquid having an initially pleasant odor which quickly becomes sharp and irritating. Table 1 Hsts the physical properties of the monomer. Information on properties, safety, and handling of vinyl acetate has been pubUshed (5—9). The vapor pressure, heat of vaporization, vapor heat capacity, Hquid heat capacity, Hquid density, vapor viscosity, Hquid viscosity, surface tension, vapor thermal conductivity, and Hquid thermal conductivity profile over temperature ranges have also been pubHshed (10). Table 2 (11) Hsts the solubiHty information for vinyl acetate. Unlike monomers such as styrene, vinyl acetate has a significant level of solubiHty in water which contributes to unique polymerization behavior. Vinyl acetate forms azeotropic mixtures (Table 3) (12). 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

0 wt % solution of sodium lauiyl sulfate organic liquids  

Second component Azeotropic boiling poiat, °C Viayl acetate, wt % 

The most important chemical reaction of vinyl acetate is free-radical polymerization (13,14). The reaction is summarized as follows  

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PVF resins [VINYL POLYhffiRS - VINYL ACETAL POLYMERS] (Vol 24)... 

Poly(vinyl acetal). See Vinyl acetal polymers. 

Emulsion Adhesives. The most widely used emulsion-based adhesive is that based upon poly(vinyl acetate)—poly(vinyl alcohol) copolymers formed by free-radical polymerization in an emulsion system. Poly(vinyl alcohol) is typically formed by hydrolysis of the poly(vinyl acetate). The properties of the emulsion are derived from the polymer employed in the polymerization as weU as from the system used to emulsify the polymer in water. The emulsion is stabilized by a combination of a surfactant plus a coUoid protection system. The protective coUoids are similar to those used paint (qv) to stabilize latex. For poly(vinyl acetate), the protective coUoids are isolated from natural gums and ceUulosic resins (carboxymethylceUulose or hydroxyethjdceUulose). The hydroHzed polymer may also be used. The physical properties of the poly(vinyl acetate) polymer can be modified by changing the co-monomer used in the polymerization. Any material which is free-radically active and participates in an emulsion polymerization can be employed. Plasticizers (qv), tackifiers, viscosity modifiers, solvents (added to coalesce the emulsion particles), fillers, humectants, and other materials are often added to the adhesive to meet specifications for the intended appHcation. Because the presence of foam in the bond line could decrease performance of the adhesion joint, agents that control the amount of air entrapped in an adhesive bond must be added. Biocides are also necessary many of the materials that are used to stabilize poly(vinyl acetate) emulsions are natural products. Poly(vinyl acetate) adhesives known as "white glue" or "carpenter s glue" are available under a number of different trade names. AppHcations are found mosdy in the area of adhesion to paper and wood (see Vinyl polymers). 

OOCCH3 vinyl acetate A-CH2—CH Vinyl POLYMERS, vinyl acetate polymers... 

Vinyl acetal polymers are made by the acid-cataly2ed acetalization of poly(viQyl alcohol) [9002-89-5] with aldehydes (1). 

Poly(vinyl alcohol) used to manufacture the poly(vinyl acetal)s is made from poly(vinyl acetate) homopolymer (see Vinyl polymers, vinyl alcohol polymers Vinyl POLYMERS, vinyl acetate polymers). Hydrolysis of poly(vinyl acetate) homopolymer produces a polyol with predominandy 1,3-glycol units. The polyol also contains up to 2 wt % 1,2-glycol units that come from head-to-head bonding during the polymeri2ation of vinyl acetate monomer. Poly(vinyl acetate) hydrolysis is seldom complete, and for some appHcations, not desired. For example, commercial PVF resins may contain up to 13 wt % unhydroly2ed poly(vinyl acetate). Residual vinyl acetate units on the polymer help improve resin solubiHty and processibiHty (15). On the other hand, the poly(vinyl alcohol) preferred for commercial PVB resins has less than 3 wt % residual poly(vinyl acetate) units on the polymer chain. 

Tackifiers are used to increase the tackiness and the setting speed of adhesives. They increase tackiness by softening the poly(vinyl acetate) polymer in the wet and the dry adhesive film. Tackifiers are usually rosin or its derivatives or phenoHc resins. Other additives frequently needed for specific apphcation and service conditions are antifoams, biocides, wetting agents, and humectants. 

Vinyl acetate polymers have long been used as chewing gum bases. They have been studied as controUed release agents for programmed administration of dmgs and as a base for antifouling marine paints (166,167). 

MATTHEWS, G. A. R., Vinyl and Allied Polymers Vol. II, Vinyl Chloride and Vinyl Acetate Polymers, lliffe, London (1972). 

Approximately 2.5 million tons of acetic acid is produced each year in the United States for a variety of purposes, including preparation of the vinyl acetate polymer used in paints and adhesives. About 20% of the acetic acid synthesized industrially is obtained by oxidation of acetaldehyde. Much of the remaining 80% is prepared by the rhodium-catalyzed reaction of methanol with carbon monoxide. 

Figure 12.5 Pyrogram of Mowilith 30, a vinyl acetate polymer used in conservation. Peak assignments 1, acetic acid 2, benzene 3, styrene 4, indene 5, 1,2 dihydro naphthalene 6, naphthalene 7, 2 methyl naphthalene 8, 1 methyl naphthalene 9, biphenyl 10, fluorene 11, anthracene...

PVA in, 25 617 setting speed of, 25 579-580 smectites application, 6 697t solution, 1 532-534 structural, 1 534-545 styrenic block copolymers in, 24 714 use of latex in, 14 711-712 vinyl acetate polymers in, 25 578-583 viscosity of, 25 581 water-borne, 25 475 Adhesive systems, microencapsules in, 16 460... 

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