Soluble resins spraying

Resin Solubilizers. In general, water-soluble resins ate amine salts of acidic polymers. Water-soluble coatings formulated with AMP-95 and DMAMP-80 exhibit superior performance (15,16) (see Water-SOLUBLE polymers). AMP-95, used in conjunction with associative thickeners (17) or hydroxy-ethylceUulose, provides for the most efficient utilization of such thickeners. It also is the neutralizer of choice for use with hair spray resins. 

Chemistry, Physics, and Biology Laboratories. As a rule, before any artifact is subjected to treatment, the chemistry laboratory determines the causes of any alterations or deterioration. The nature and structure of the artifact, its pigments and inks, are identified to avoid negative reactions to prescribed treatment. Fixatives are recommended if required these may be cellulose acetate dissolved in acetone, soluble nylon, or acrylic resin sprays. Once stains are identified, several possible solvents are selected. For deacidification, either magnesium bicarbonate or barium hydroxide usually is recommended, depending on whether an aqueous or nonaqueous solution is called for. Bleaching is discouraged, but when necessary, hypochlorites are used with suitable antichlors. 

Use Solvent for nitrocellulose resins, spray lacquers, quick-drying lacquers, varnishes, enamels, dry-cleaning compounds, varnish removers, textile (preventing spotting in printing or dyeing) mutual solvent for soluble mineral oils to hold soap in solution and to improve the emulsifying properties. 

In the preparation of water-soluble resins for use or for subsequent spray drying, the solution of methylol compounds is further heated under alkaline or slightly acid conditions (pH 5.0-8.6, depending on the systems used) until the derired viscosity or solubility characteristics are obtained from increased molecular weight. The molecular weight is increased by way of reactions 2, 3, and 4. On further heating these reactions continue until a large three-dimensional network is built up which is insoluble and infusible. 

Solution vehicles consist of water soluble polymers not manufactured by emulsion polymerization. The solution vehicle is an alkali soluble polymer in aqueous solution or a blend of polymers with combined properties into a single waterborne varnish. Soluble polymers are made by free radical polymerization in a processing solvent or as addition or condensation products with heat reaching temperatures up to 265 °C. Solution vehicles are mixtures of soluble resins unlike emulsion polymers. A solution vehicle is used to increase adhesion to film and improve ink printabihty or transfer to meet specific performance requirements. The solution vehicle provides pigment dispersion stabilization, transparency, low film forming temperature, gloss and re-solubility. An alkali soluble resin is a carboxylic acid functional polymer neutralized (solubilized) with ammonia, amine or sodium hydroxide. The add numbers are generally above 100. Ammonia or volatile amines are used in most aqueous inks except for news print inks. After evaporation of the amine, the resin becomes insoluble and resistant to water spray or other water contact. The ink is re-solubilized with alkaline water for the clean-up cycle. For news print ink, the polymers are solubiHzed with sodium hydroxide to maintain re-solubility (open time) of the ink on the press. News print ink pressman prefer unlimited open time and fewer clean-up cycles. Water resistance is not required since ink penetrates the news print paper fibers. 

Surface Applied Surfactants. Antistat agents can be appHed direcdy to the surface of a plastic part. Usually the antistat is diluted in water or in a solvent. The antistat solution is appHed by spraying, dipping, or wiping on the surface. The water or solvent dries leaving a thin film that attracts moisture. Since it is appHed to the surface, migration through the resin is not a factor. In practice, the quaternary ammonium compounds find the most use. They are soluble in water and effective at low concentrations. 

Amino Resins. Amino resins (qv) include both urea- and melamine—formaldehyde condensation products. They are thermosets prepared similarly by the reaction of the amino groups in urea [57-13-6] or melamine [108-78-1] with formaldehyde to form the corresponding methylol derivatives, which are soluble in water or ethanol. To form plywood, particle board, and other wood products for adhesive or bonding purposes, a Hquid resin is mixed with some acid catalyst and sprayed on the boards or granules, then cured and cross-linked under heat and pressure. 

After hardening, UF-resins consist of insoluble, more or less three-dimensional networks and cannot be melted or thermoformed again. At their application stage, UF-resins are still soluble or dispersed in water or are spray dried powders, which in most cases are redissolved and redispersed in water for application. 

A low acid polyvinyl butyral-based pretreatment primer ( etch or wash primer are alternative names) is usually advantageous as the first treatment of a metal-sprayed surface before painting. Up to an equal volume of spirit soluble phenolic resin is used as a diluent to the polyvinyl butyral of conventional pretreatment primers. This has an incidental, but particularly valuable effect, in reducing the free acid available to penetrate into the pores of the coating. The modified pretreatment primer is highly water resistant and this helps to avoid damage due to condensation. 

A characteristic of the group (a) of resins is that they air-dry solely by solvent evaporation and remain permanently solvent soluble. This fact, combined with the need to use strong solvents, makes brush application very difficult, but sprayed coats can be applied at intervals of one hour. A full vinyl system such as (o) possesses excellent chemical and water resistance. Many members of group (o) have very poor adhesion to metal, and have therefore been exploited as strip lacquers for temporary protection. Excellent adhesion is, however, obtained by initial application of an etching primer the best known of such primers comprises polyvinyl butyral, zinc tetroxy-chromate and phosphoric acid. 

Desirable fixative properties superior to PVP homopolymer can be specified by judicious selection of the amount of vinyl acetate. Hair sprays are limited in the molecular weight of the resin because if they are too hLgh the resulting viscosity of the formulation will result in a poor (coarse) spray pattern. Increasing the VP/VA ratio causes properties to increase in the direction shown by the arrows. Other applications for VP/VA copolymers are uses as water-soluble or remoistenable hot melt adhesives, pharmaceutical tablet coatings, binders, and controlled-release substrates. 

Emulsion Polymerization. Emulsion polymerization takes place in a soap micelle where a small amount of monomer dissolves in the micelle. The initiator is water-soluble. Polymerization takes place when the radical enters the monomer-swollen micelle. Termination takes place in the growing micelle by the usual radical-radical interactions, The high solubility of vinyl chloride in water, 0.6 wt %. accounts for a strong deviation from true emulsion behavior. Also, PVC s insolubility in its own monomer accounts for such behavior as a rate dependence on conversion. Emulsions of up to 0.2- im dia are sold in liquid form for water-based paints, printing inks, and finishes for paper and fabric. Other versions, 0.3-10- j.m dia and dried by spray-drying or coagulation, are used as plastisol resins. 

Under the real conditions of high temperature spraying, the surface tension and the solubility of the surfactant (e.g. Proxanol 305) are changed and the droplets are not as stable. The number of microspheres is the same as it is for organo-silicon surfactants, while there are fewer polycellular microspheres than were produced in the absence of a surfactant. Those surfactants that increase the gas content in the resin also increase the yield of hollow microspheres 34). The addition of a surfactant increases the yield of polycellular particles in most cases, though their number decreases as the temperature increases. 

Urea (NH2CONH2) reacts with formaldehyde similarly to phenol to produce methylol derivatives that then condense further to yield a cross-linked network (Scheme 1). Actually, at a mole ratio of 1.5-2 mol of formaldehyde to urea and a pH of 7.5, a mixture of the monomethylol, dimethylol, trimethylol, and tetramethylol ureas are formed. For further extensive condensation to take place, the pH of the system must be made acidic. Thus, it is possible to concentrate the initial resin solution or spray-dry it to a soluble powder that can be dissolved and mixed with an acid catalyst at the time of application to induce the curing reaction. The ratio of formaldehyde to urea used in commercial resins varies with the manufacturer, but is always less than 2 1. 

Plyophen [Reichhold], TM for a water-soluble impregnating resin. Penetrates deeply and quickly into wood, canvas, asbestos, paper, and other laminating and molding stocks. Can be diluted as much as 8-10 parts water to 1 part resin for spraying glass fiber or rock wool. 

Resimene [Solutia]. TM for melamine and ureaformaldehyde resins. Supplied in organic liquid solutions. The melamine is also available in water-alcohol and soluble, spray-dry powders. 

With a view to lowering raw material costs (the DMPA used in binder LR-2052 is rather expensive), we later developed another OH-rich binder, designated LR-2053. This system is based on a linear backbone containing a liquid epoxy resin, EPIKOTE 828, diphenylolpropane, adipic acid and CE 10 (molar ratio 3/2/2/2) and again is rendered water-soluble with a TMA/CE 10 combination (2.5 moles TMA and 2.6 moles CE 10 per mole of backbone). This binder performs as well as LR-2052, with an only marginally lower salt-spray resistance. 

The increased solubility of vinyl polymers in solvents at elevated temperatures enables very high solids to be obtained for application techniques like hot airless spraying or curtain coating. Figure 33 illustrates this property with a vinyl chloride-trifluorochloroethylene copolymer at 25° to 95°C. Since the solubility of the resin improves with... 

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