Poly phenolic adhesives

Although the manufacture and sale of adhesives is a worldwide enterprise, the adhesives business can be characterized as a fragmented industry. The 1987 Census of Manufacturers obtained reports from 712 companies in the United States, each of which considers itself to be in the adhesives or sealants business only 275 of these companies had more than 20 employees. Phenolics, poly(vinyl acetate) adhesives, rubber cements, and hot-mclt adhesives arc the leading products in terms of monetary value. These products are used primarily in llie wood, paper, and packaging industries. The annual growth rate of the adhesives market is 2.3%, and individual segments of the market are expected to grow faster than this rate. 

Phenolic resin adhesive films (Resinous Products Chemical Co.) Poly(vinyl acetate) adhesives (Carbide Carbon Chemicals Co.) Chlorinated rubber adhesives... 

The main application of poly (vinyl formal) is as a wire enamel in conjunction with a phenolic resin. For this purpose, polymers with low hydroxyl (5-6%) and acetate (9.5-13%) content are used. Similar grades are used in structural adhesive (e.g. Redux) which are also used in conjunction with phenolic resin. Poly(vinyl formal) finds some use as a can coating and with wash primers. Injection mouldings have no commercial significance since they have no features justifying their use at current commercial prices. 

Compared with the phenolics and polyesters the resins have better heat resistance, better chemical resistance, particularly to alkalis, greater hardness and better water resistance. In these respects they are similar to, and often slightly superior to, the epoxide resins. Unlike the epoxides they have a poor adhesion to wood and metal, this being somewhat improved by incorporating plasticisers such as poly(vinyl acetate) and poly(vinyl formal) but with a consequent reduction in chemical resistance. The cured resins are black in colour. 

Resistance to weathering. Zinc oxide and magnesium oxide stabilize poly-chloroprene against dehydrochlorination. Further, zinc oxide helps vulcanize the rubber, and magnesium oxide reacts with /-butyl phenolic resin to produce a resinate which improves heat resistance of solvent-borne polychloroprene adhesives. 

Tanno, T. and Shibuya, L., Special behaviour of para tertiary phenol dialcohol in poly-chloroprene adhesives. Adhesives and Sealant Council Meeting, Spring 1967. 

The PVF is made by acidic reaction between poly(vinyl alcohol) (PVA) and formaldehyde. The poly(vinyl alcohol) is, in turn, made by hydrolysis of poly(vinyl acetate) or transesterification of poly(vinyl acetate). Thus, residual alcohol and ester functionality is usually present. Cure reportedly occurs through reaction of phenolic polymer hydroxyls with the residual hydroxyls of the PVA [199]. The ester residues are observed to reduce bond strength in PVF-based systems [199]. This does not necessarily extend to PVF-P adhesives. PVF is stable in strong alkali, so participation of the acetals in curing is probably unimportant in most situations involving resoles. PVF is physically compatible with many phenolic resins. 

Phenolics are used in bonding wood and plywood. They are also good adhesives for automobile brake linings. A phenolic plus poly(vinyl butyral) is used to bond copper to paper or glass fiber for printed circuits. 

Adhesives. High concentration (>10%) solutions of poly (ethylene oxide) exhibit wet tack properties that are used in several adhesive applications. The tackiness disappears when the polymer dries and this property can be successfully utilized in applications that require adhesion only in moist conditions. PEO is also known to form solution complexes with several phenolic and phenoxy resins. Solution blends of PEO and phenoxy resins are known to exhibit syneigistic effects, leading to high adhesion strength on aluminum surfaces. Adhesive formulations are available from the manufacturers. 

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 phenolic resins. Other additives frequently needed for specific application and service conditions are antifoams, biocides, wetting agents, and humectants. 

Isolation and Characterization of cDNA Clones Encoding the Poly-phenolic Protein. Characterization of the primary amino acid sequence of the mussel adhesive protein has been hindered by the large size of the protein and the repetitiveness of the amino acids. In such cases, the practical (and perhaps only) approach for determining the complete amino acid sequence is to clone DNA sequences encoding the protein and to deduce the amino acid sequence from the genetic code carried by that DNA. To accomplish this, we obtained mRNA from mussels and synthesized cDNA in vitro. 

Poly(vinyl alcohol) is utilized as a component of starch-based adhesives.11121114 Other patents report the use of partially oxidized starch,1115 dextrins,1116 dextrins and urea,1117 borax,1118 boric acid,1119 and vinyl methyl ether-maleic acid copolymers.1120 Other patents indicate the use of poly (vinyl alcohol) with partially hydrolyzed poly(vinyl acetate),1121 nonhy-drolyzed poly(vinyl acetate),1122 and poly(vinyl chloride).1123 A few patents have reported such poly acrylic additives as poly (acrylic acid)1124 and its salts,1125 poly(acrylamide),1126 1127 A-methylacrylamide or poly(A-acryl-amide),1128 and polyethyleneimine.1129 Polystyrene has also been used,1130 as well as more complex copolymers such as a maleic acid monobutyl ester-methyl vinyl ether copolymer, together with dextrin and polyacrylamide),1131 carboxylated ethyl acrylate-styrene zinc salt copolymer,1132 ethylene-methyl acrylate-vinyl acetate copolymer,1133 vinyl acetate-vinyl pyr-rolidone copolymer,1134 and ethylene-vinyl acetate copolymer.1135 Some adhesives are compounded with SBR latex1136 1138 and phenol-formaldehyde resins.1139... 

The enzymatic treatment of chitosan in the presence of tyrosinase and phenol derivatives produced new materials based on chitosan.91 During the reaction, unstable o-quinones were formed, followed by the reaction with the amino group of chitosan to give the modified chitosan. The tyrosinase-catalyzed modification of chitosan with phenols dramatically altered rheological and surface properties of chitosan. The modification with chlorogenic acid onto chitosan conferred the water solubility of chitosan under basic conditions.92 A new water-resistant adhesive was developed by the tyrosinase-catalyzed reaction of 3,4-dihydroxyphenethylamine and chitosan.93 Poly(4-hydroxystyrene) was modified with aniline by using tyrosinase catalyst.94 The incorporated ratio of aniline into the polymer was very low (1.3%). 

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