Cellulose Biocidal Polymers

Emulsion Adhesives. The most widely used emulsion-based adhesive is that based upon poly (vinyl acetate)—polytyinyl 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 well as from the system used to emulsify the polymer in water. The emulsion is stabilized by a combination of a surfactant plus a colloid protection system. The protective colloids are similar to those used paint (qv) to stabilize latex. For poly (vinyl acetate), the protective colloids are isolated from natural gums and cellulosic resins (carboxymethylcellulose or hydroxyethylcellulose). The hydrolized 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 application. 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. Applications are found mostly in the area of adhesion to paper and wood (see VlNYL POLYMERS). 

Cellulose based plastics and certain PVC formulations are vulnerable to attack from microorganisms. Specific biocides are targeted at particular organisms and can be more precisely defined as bactericides, fungicides, etc. Antimicrobial additives are now widely used in polyolefin kitchenware and bathroom accessories to act in defence of substances coming into contact with the polymer. EUROPEAN COMMUNITY EUROPEAN UNION UK WESTERN EUROPE... 

The physically bonded solution preparations rely on diffusion for the most part for release from the polymer. Also possible is a chemical or biological erosion of the matrix to release the agent. The biocide is trapped in a hard plastic, such as nylon, polyethylene, or poly(vinyl chloride) a rubber or in a natural polymer, such as cellulose or starch. 

To obtain a suitable coating viscosity, and to prevent settling of filler particles, thickeners are often used. These are often low-cost natural products based on cellulose or casein. These are readily metabolized by many bacteria and fungi therefore, a biocide should be included. Biocides in powder form such as Captan (R.T. Vanderbilt) or Zinc Omadine (Akcros) can be dispersed with fillers and pigments. A useful starting point level is 1 percent by weight of the natural polymer to be protected. Alternatively, a biocide water dispersion, such as Nuocide 404-D (40.4%, International Specialty Products), can be used. 

Cellulose (cotton) and natural rubber are biodegradable polymers that have had many uses over the years, almost none of them benefiting from biodegradability. In fact, the treatment of cotton to combat mildew and the addition of biocides to latex compounds is much more in the tradition of commercial uses than working in the opposite direction. 

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