Adhesion alkaline improvement

Thermal and Alkaline Improvement of Adhesion in Globular Proteins... 

Alkaline-dispersed amylaceous materials in phenolic plywood adhesives for improved assembly time tolerance and prepress tack. 

Ethyl Vinyl Ether. The addition of ethanol to acetylene gives ethyl vinyl ether [104-92-2] (351—355). The vapor-phase reaction is generally mn at 1.38—2.07 MPa (13.6—20.4 atm) and temperatures of 160—180°C with alkaline catalysts such as potassium hydroxide and potassium ethoxide. High molecular weight polymers of ethyl vinyl ether are used for pressure-sensitive adhesives, viscosity-index improvers, coatings and films lower molecular weight polymers are plasticizers and resin modifiers. 

Titanium dioxide used for adhesive applications should contain an inorganic coating to control polarity, improve its ease of dispersion, and improve its weather resistance. The inorganic coating (zirconium dioxide, silica, alumina) is applied in the aqueous sluny by precipitation of one or more hydrated metal oxides and by neutralization of acidic and alkaline compounds. 

Aqueous solutions of permanganate will slowly oxidize, forming a brown film [not clear if this is Mn203, Mn02, or Mn(0)OH] on the walls of the vessel in which it is stored. Increase of either acidity or alkalinity of the solution can accelerate this decomposition reaction. This reaction has been used to treat polymer substrates prior to chemical deposition, for improved adhesion [32]. hi that work, the Mn—O film was dissolved before the CD process, and the improved adhesion was probably dne to some increase in the hydrophilic character of the mostly hydrophobic polymers. 

The gluability of the lignin-epoxy resin adhesives was found to be improved by the addition of calcium carbonate (50% by weight) to the liquid resin. This must be attributed to the nature of the weak alkali in calcium carbonate as a cure accelerator, and to the reinforcement effect of fillers. Since wood surfaces are acidic, the addition of alkaline fillers effectively alters the pH of the glue line. 

Early attempts to use mimosa tannin in particleboard adhesives involved high-temperature alkaline treatment of the extract to reduce viscosity of the 40% solids level needed (43,44) Subsequent improvements followed the same course as with plywood, namely the use of phenol-formaldehyde or phenol-resorcinol-formaldehyde as crosslinking agents (45) and the use of catalysts or mix modifications to reduce press temperature requirements and to extend pot life. Recent work (46) has shown that exterior chipboard adhesives can also be prepared by crosslinking of mimosa tannins with 4,4-diphenylmethane diisocyanate. 

PMDA has also been claimed to improve the quality of polyester based adhesives(26), acrylics(27), and epoxies(29). The inclusion of PMDA into thermoplastic and copolyester rubber, with alkaline earth filler, is claimed to make an excellent hot-melt adhesive(30). 

Highly diffusive penetration of SPC can be drastically lowered by active additives that are capable of raising SPC density, and, therefore, its corrosion resistance. As indicated previously, the most effective results were obtained by introduction of FA or TFS additives. Addition of monomeric additives to silicate composition improves the physical-mechanical characteristics and chemical resistance of silicate compositions due to improvement in the quality of silicate bonds and better adhesion between the binder and coarse filler [1], In other words, the influence of the monomeric additives is conditioned by consolidation of liquid glass gel during hardening and modifications of alkaline components due to inoculation of furan radicals. 

Alkalies and Acids. The older literature dealing with the treatment of soybean proteins with alkaline substances is quite extensive since these agents have often been used for protein extraction, solubilization, and property modification, including improved solubility, increased adhesive properties, and lower viscosity in dispersion and fiber formation (12, 21, 23, 24). The alkali treatment of soy protein for industrial use is done under conditions which are more severe (higher temperature and higher pH, such as possibly 50 °C at pH >13) than those intended for food usage. 

Attempts have been made over time to improve the physical properties of novolacs. The use of phenol formaldehyde resins prepared in alkaline medium in photoresist compositions is mentioned in a Kalle Co. AG patent. The use of polyvinyl ethers in combination with novolacs to impart stickiness and plasticization action to the latter was patented by Christensen. Steinhoff, Isaacson, and Roelants of the Shipley Company mention the use of vinyl ethers in a patent on roller coating. Lower alkyl polyvinyl ethers, such as methyl, ethyl, butyl, and isobutyl, are added to novolac resins to improve coating flexibility and adhesion to metal surfaces as well as to improve resistance to mildly alkaline solutions. The use of styrene, methyl styrene, and styrene-maleic anhydride copolymers in combination with novolac was mentioned in several patents of both Shipley and Kalle Co. AG. When novolac is copolymerized with maleic anhydride, a resin that is readily soluble in alkaline solutions is obtained. ... 

Surface oxidation reactions have been carried out on a number of polymers, particularly polyethylene. Surface oxidation techniques include the use of corona discharge, ozone, hydrogen peroxide, nitrous acid, alkaline hypochloride, UV irradiation, oxidizing flame, and chromic acid The reactions lead initially to the formation of hydroperoxides, which catalyze the formation of aldehydes and ketones and finally, acids and esters. Surface oxidation treatment has been used to increase the printabdity of polyethylene and poly(ethylene terephthalate) and to improve the adhesion of polyethylene and polypropylene to polar polymers and that of polytetrafluoroethylene to pressure-sensitive tapes. Surface-oxidized polyethylene, when coated with a thin film of vinylidene chloride, acrylonitrile, and acryhc acid terpolymers becomes impermeable to oxygen and more resistant to grease, oil, abrasion, and high temperatures. The greasy feel of polyethylene has also been removed by surface oxidation. 

To process soybeans into these useful products, the beans are dehulled and the oil is removed by crushing at very high pressure or by solvent extraction. If the resulting dry soybean meal is intended for food, it is heated to 70°C or higher to coagulate the proteins and caramelize the carbohydrates, thus improving their nutritional qualities. If the soybean meal is intended for adhesive use, it is processed at temperatures below 70°C to preserve the alkaline solubility of the proteins [16]. 

---