Consumer-type adhesives

The exceptionally fast rate of anionic polymerization of cyanoacrylates in the presence of a base, including water, made this class of monomers unique among all acrylic and vinyl monomers. Of the alkyl cyanoacrylate family of monomers, fhe mefhyl- and ethyl-esters are used extensively in industrial and consumer-type adhesives. Meanwhile, the isobutyl, fi-butyl, and n-octyl cyanoacrylate esters are used clinically as blocking agents, sealants, and/or tissue adhesives in different parts of the world due to their much lower toxicity as compared to their more reactive methyl coxmterpart. 

As previously pointed out, film adhesives account for the major share of structural adhesives consumed by the aerospace industry. Therefore, this discussion of chemical types of adhesive, after making some general comments on other types, will be limited to film-type adhesives. 

Rubber. The mbber industry consumes finely ground metallic selenium and Selenac (selenium diethyl dithiocarbamate, R. T. Vanderbilt). Both are used with natural mbber and styrene—butadiene mbber (SBR) to increase the rate of vulcanization and improve the aging and mechanical properties of sulfudess and low sulfur stocks. Selenac is also used as an accelerator in butyl mbber and as an activator for other types of accelerators, eg, thiazoles (see Rubber chemicals). Selenium compounds are useflil as antioxidants (qv), uv stabilizers, (qv), bonding agents, carbon black activators, and polymerization additives. Selenac improves the adhesion of polyester fibers to mbber. 

Global consumption of thermoplastic mbbers of all types is estimated at about 600,000 t/yr (51). Of this, 42% was estimated to be consumed in the United States, 39% in Western Europe, and 19% in Japan. At present, the woddwide market is estimated to be divided as follows styrenic block copolymers, 48% hard polymer/elastomer combinations, 26% thermoplastic polyurethanes, 12% thermoplastic polyesters, 4% and others, 9%. The three largest end uses were transportation, 23% footwear, 18% and adhesives, coatings, etc, 16%. The ranges of the hardness values, prices, and specific gravities of commercially available materials are given in Table 4. 

Although formaldehyde emissions from some products glued with urea formaldehyde adhesives can cause indoor air quality problems under certain conditions, such problems have not been associated with phenol formaldehyde-bonded (phenolic) products. Unfortunately, however the commonplace usage of the generic terms particleboard and plywood has failed to distinguish between product types and has led to a great deal of confusion among consumers. 

Besides consumer products, another important field of application for PSAs is that of plastic adhesive labels. The PSAs must adhere very efficiently to the plastic carrying material and at the same time adhere well to a wide variety of plastic packaging types (e.g., bottles, containers for chemicals). 

More than half of vinyl acetate monomer is used in polyvinyl acetate emulsions and resins. The largest use of polyvinyl acetate emulsions is in adhesive emulsions. This is followed by use in copolymers to produce latex paints which have largely replaced solvent-based paints in developed countries. The adhesive emulsions are used in all types of consumer adhesives and glues used in the construction industry. 

Surlyn heat seal layer breaks away from the HDPE layer and then falls across the Surlyn layer. This type of peel seal is used, but it has its problems. If the interlayer adhesion is too much weaker than the strength of the Surlyn film layer, one ends up with a bag in a bag, which does not make the consumer happy. 

There is a wealth of information available to the researcher on adhesives and sealants. Finding the exact item of interest on those materials, however, can be a daunting and very time-consuming task. There is no central collection point for this information. There are, literally, hundreds of companies that manufacture adhesives and sealants, there are dozens of market research firms that report on the activities of those manufacturers, there are numerous government agencies that track the activity of those manufacturers, and there are several types of directories that list companies working in this industry. 

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