Adhesives starch ethers

In industrial production of acid-modified starches, a 40% slurry of normal com starch or waxy maize starch is acidified with hydrochloric or sulfuric acid at 25—55°C. Reaction time is controlled by measuring loss of viscosity and may vary from 6 to 24 hs. For product reproducibiUty, it is necessary to strictly control the type of starch, its concentration, the type of acid and its concentration, the temperature, and time of reaction. Viscosity is plotted versus time, and when the desired amount of thinning is attained the mixture is neutralized with soda ash or dilute sodium hydroxide. The acid-modified starch is then filtered and dried. If the starch is washed with a nonaqueous solvent (89), gelling time is reduced, but such drying is seldom used. Acid treatment may be used in conjunction with preparation of starch ethers (90), cationic starches, or cross-linked starches. Acid treatment of 34 different rice starches has been reported (91), as well as acidic hydrolysis of wheat and com starches followed by hydroxypropylation for the purpose of preparing thin-hoiling and nongelling adhesives (92). 

Additional information on starch ethers has been reported by Pringsheim,1264 Hjermstad1265 as well as Banks and coworkers,1266 and Mishler1267 [only (hydrox-yethyl)starch], Omae and coworkers1268 [only (hydroxypropyl)starch adhesives], Hjermstad,1269 Mehltretter,1270 Moser1271 [(hydroxyethyl)starch], Tuschhoff1272 [(hydroxypropyl)starch], and Wurzburg1273 (crosslinked starches). 

Adhesives used in size formulations include starches (natural such as potato, maize or sago, or chemically modified, e.g. starch ethers), natural gums (guar, carob or locust bean flour), gelatin, Polyvinyl alcohol, polyacrylic acid, vinyl and acrylic resins and sodium carboxymethyl cellulose (SCMC). 

In addition, they are used in combination with casein solutions and synthetic resin emulsions. Whereas starch ethers and esters and also aldehyde starches are used to only a limited extent in the adhesives field, the thermal degradation products of starches, the water-soluble dextrins, are still important in quantitative terms as raw materials for adhesives. They are used on their own in aqueous form or as mixtures with synthetic resin emulsions. 

Other Aqueous Adhesive Solutions. Besides starches and dextrins, cellulose ethers, primarily methyl cellulose and carboxymethyl cellulose, and in some cases also starch ethers, are important as wallpaper pastes and poster glues. The products are generally marketed in the form of powders that are dissolved in water by the user. Aqueous... 

The adhesives are based on methyl cellulose, starch ethers, carboxymethyl cellulose, pre-gelatinized starch, poly(vinyl acetate), polyacrylate, styrene-butadiene latices, polychlorobutadiene, and polyurethanes. The viscosity of the adhesives covers the range from fluid to pasty. 

Wallpapers include those with a PVC or metal surface and rough-textured plain wallpapers. They are applied with pastes of pre-gelatinized starch, starch ethers, carboxymethyl or methyl cellulose in the form of 2-10% solutions. For rough-textured plain wallpapers and heavy wallpapers, moisture resistance and tack are increased by utilizing poly(vinyl acetate) redispersion powders. High solid, emulsion-based adhesives, optionally in conjunction with resin-enhanced pastes (special purpose pastes), are used preferably for heavy vinyl- and metal-faced wallpapers. 

Throughout the 1990s a large portion of the research and development effort for hot melt adhesives focused on developing adhesives that are either environmentally friendly or functional [69,81,82]. Environmentally friendly attributes include biodegradability, water dispersibility (repulpability), renewability, and water releasability. Biodegradable adhesives have been developed based on starch esters [83-86] and polyesters such as poly (hydroxy butyrate/hydroxy valerate) [87], poly(lactide) [88-91], and poly(hydroxy ether esters) [92-94]. All but the... 

Amylopectin is the polymeric component of starch and consists mainly of glucose units joined at the 1,4-positions. Relative molar mass tends to be very high, e.g. between 7 and 70 million. A variety of modified starches are used commercially which are produced by derivatisation to give materials such as ethanoates (acetates), phosphates, and hydroxyalkyl ethers. Modified and unmodified starches are used in approximately equal tonnages, mainly in papermaking, paper coatings, paper adhesives, textile sizes, and food thickeners. 

Some beer bottle manufacturers have added poly(vinyl alcohol) to the adhesive to ensure resistance to iced water yet retain washability in the bottling operation. Others have used the starch paste to extend the more water-resistant casein adhesives (0). Newer adhesives are being developed based on double treatments of starches such as hydroxyalkyl ethers of oxidized starch, blending these products with other specified polymers (12,13) or adding synthetic resins... 

Sealing tape has 35 to 90 pounds per ream of kraft paper as a substrate, whereas, reinforced sealing tape is based on a bonded laminate of kraft paper, reinforcing fibers, and kraft paper. The adhesives applied to these substrates may be thin-boiling, waxy starches alone, or blended with a soluble dextrin (5). More recently, blends of a soluble dextrin with oxidized potato or a hydrox-ypropyl ether of an oxidized potato starch are being used (9). Also, the acetate or succinate of an oxidized waxy starch may be used (15) as well as specially produced waxy starch acrylamide graft copolymer products (16). 

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... 

Hexahydro-1,3,5-triethyl-s-triazine. Industrial preservative, prevents bacterial action in cutting oils, synthetic rubber latex, starch based adhesives, latex paint and aqueous slurries. It is soluble in acetone, ethyl alcohol, ether and water, moderately soluble in hydrocarbon solvents. 

Epichlorohydrin is usually prepared from propene and is mainly used in the manufacture of glycerol and epoxy resins. It is also used in the manufacture of elastomers, glycidyl ethers, cross-linked food starch, surfactants, plasticizers, dyestuffs, pharmaceutical products, oil emulsifiers, lubricants, and adhesives as a solvent for resins, gums, cellulose, esters, paints, and lacquers and as a stabilizer in chlorine-containing substances such as rubber, pesticide formulations, and solvents. 

Useful film-forming resin adhesives include polyvinyl esters and ethers and their copolymers and interpolymers with ethylene and vinyl monomers, acrylic resins and their copolymers, polyvinyl alcohol, water dispersion of polyolefin resins, polystyrene copolymers such as polystyrene butadiene, polyamide resins, natural rubber dispersions, and natural and modified carbohydrates (starch or carboxycellulose). Particularly preferred for use are aqueous dispersions of polyvinyl acetate and vinyl acetate-ethylene copolymers. 

Chem. Descrip. 2-Bromo-2-nitropropane-1,3-diol (Canguard 409), dipropylene glycol monomethyl ether, and water Uses Preservative in adhesives, printing inks and fountain solutions, starch, pigment and extender slurries and paints, latex and antifoam emulsion systems... 

Starches are modified chemically in various ways. Some acetate and phosphate esters are produced commercially, as well as hydroxyalkyl and tertiary aminoalkyl ethers. Both unmodified and modified starches are used principally in paper making, paper coating, paper adhesives, textile sizes, and as food thickeners. There are many reports in the literature on graft copolymers of starch. The work is often conducted is search of biodegradable materials for packaging and agricultural mulches. Most chemical modifications of starch parallel those of cellulose. 

Potassium palmitate PPG-15 PPG-2-buteth-2 PPG-22 butyl ether PPG-30 butyl ether Propylene glycol dicocoate Propylene oxide Sperm oil Starch acetate Starch, oxidized Tetramethylthiuram monosulfide Trichloroethylene Trioctyl phosphate Tripotassium EDTA Vinyl acetate Vinyl chloride/vinylidene chloride copolymer adhesive, food-contact Hydroabietyl alcohol Phenoxy resin Polybutene Propylene glycol soyate... 

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