Adhesives, starch hydrolyzates

Currently, only hydrolases (amylases) are used to modify starch. The use of amylases to produce products derived from hydrolysis of starch is described in Chapters 7,20, 21 and 22. Starch hydrolyzates with good adhesion property that can be applied at high solids to minimize the energy required to remove moisture after application are very desirable for coating food items with seasonings, flavors and colorants. This property can be achieved by treating starch with an amylase or amylases to a dextrose equivalency (DE) (see Chapter 21) of 2-40.228 Waxy maize is the preferred starch. 

Amylase facilitates the removal of starch-containing stains such as those from pasta, potato, gravy, chocolate, and baby food. Dried-up starch is difficult to remove from medium- to low temperatures. Amylase adheres to the surface of laundry, acting as an adhesive for other stain components. Starch acts as a kind of glue which binds particulate soil to the surface. Amylase hydrolyzes the starch into dextrins and oligosaccharides the latter are readily dissolved in the washing liquor and thus successively diminish the stain. Likewise, dried-on food, in particular stains and films from starch-containing foods, may be difficult to remove in a dishwasher. 

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... 

Paste, n—An adhesive composition having a characteristic plastic-type consistency, that is, a high order of yield value, such as that of an adhesive prepared by heating a mixture of starch and water and subsequently cooling the hydrolyzed product. 

The use of an oxidized starch acetate 180, urea 20, and water 200 as a gummed tape adhesive has been patented. The formulation of an acrylamide starch graft polymer is also claimed hydrolyzed low viscosity acrylamide-starch graft copolymer 67, canary dextrin 20, animal glue 10, urea 10, petrolatum 0.25, and sodium hexametaphosphate 0.1, are heated for 30 minutes at 185-205 F (85-96 C). ... 

Adhesives have been a technologically important application of polymers for thousands of years. Many of the early natural adhesives are still used. These include starch and protein-based formulations such as hydrolyzed collagen from animal hides, hooves, and bones, and casein from milk. As new adhesive formulations based on synthetic polymers (often the same polymers used in other applications) continue to be developed, the range of applications for adhesives has expanded dramatically [1-7]. 

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