Urethane alkyd

Urethane acrylates Urethane adhesives Urethane alkyds Urethane-based resins... 

Silicone alkyds Urethane alkyds Epoxy esters Tung oil phenolic... 

Urethane alkyds These are formed by the reaction of an isocyanate with alkyd, although the curing remains substantially through the oil-oxidation reaction. They have properties similar to alkyds although superior resistance to abrasion is claimed. 

When samples of about 1 cm were taken from a single cast film of 100 X 200 mm of a number of paint and varnish films, their resistances varied with the concentration of potassium chloride solution in one of two ways (Fig. 14.2). Either the resistance increased with increasing concentration of the electrolyte (inverse or / conduction) or the resistance of the film followed that of the solution in which it was immersed (direct or D conduction). The percentage of / and D samples taken from different castings varied, but average values for a number of castings were 50% D for the pentaerythritol alkyd and the tung oil phenol formaldehyde varnishes, 57% for urethane alkyd, 76% for epoxypolyamide and 78% for polyurethane varnishes... 

Urethane alkyds and urethane oils are oil and alkyd resin-modified polyurethanes dissolved in a volatile solvent. Upon application and solvent evaporation, the coating is crosslinked and cured via oxidation by atmospheric oxygen. 

Unsaturated polyester resins (UPRs) Uralkyd resins, 202 Urea-methylol reaction, 410 Urethane alkyds, 241 Urethane coatings, 202 Urethane elastomers, implanted, 207 Urethane foams, tests for, 244 Urethane gels, 205 Urethane-grade ATPEs, 223 Urethane-grade polyol types, 212 Urethane-grade raw materials, 246 Urethane hydrogel, preparation of, 250-251... 

Urethanes (alkyd resin plus diisocyanate) bind sand to form a temporary mold in many foundry operations. 

Although blending with other coating resins provides a variety of ways to improve the performance of alkyds, or of the other resins, chemically combining the desired modifier into the alkyd structure eliminates compatibility problems and gives a more uniform product. Several such chemical modifications of the alkyd resins have gained commercial importance. They include vinylated alkyds, silicone alkyds, urethane alkyds, phenolic alkyds, and polyamide alkyds. 

The resulting unsaturated diols (practically monoglycerides of fatty acids, reaction 17.12) react with diisocyanates (for example with toluene diisocyanate) at around 80-90 °C, usually in a solvent such as toluene, xylene or naphtha. Unsaturated PU are obtained, which are crosslinked by a radical mechanism with the transformation of the multiple double bond in a crosslinked network (Figure 17.9). This reaction is used for the fabrication of urethane alkyd coatings. Other polyols may be used instead of glycerol ethylene glycol, neopentylglycol, trimethylolpropane, pentaerythritol and others. 

The mechanism of curing urethane alkyd resins is based on the oxidation with molecular oxygen of the allylic position (reaction 17.13). 

Figure 17.9 Radical crosslinking of urethane alkyd resins...

The radicals formed RO and HO, initiate the crosslinking reaction. Soybean oil, sunflower oil and safflower oil give semi-drying urethane alkyds but high unsaturated oils, such as linseed oil give drying urethane alkyds. 

One-Package Urethane Alkyd (Oil-Modified Urethanes) Coatings (ASTM Type 1)... 

Figure 4.28 The results of a library search of the spectrum from the middle layer of the laminate. The top spectrum is that collected from the sample the bottom spectrum, urethane alkyd, is the best match found in the search of a polymer database. Other possible compounds are suggested by the search routine and listed in the box below the spectra. Note the match number—the higher the number, the better the agreement between the sample spectrum and the library spectrum. [Courtesy of ThermoNicolet, Madison, WI (www.thermonicolet.com).]...

Uses Pigment for alkyds, oil-based exterior and interior paints and stains, oil-modified urethanes, alkyd melamines, and other systems Colormatch AD-10306 [Plasticolors]... 

Uses Detoamer, air release agent tor water-based industrial coatings, high-solids coatings, acrylic urethanes, alkyds, epoxies, printing inks, wood lacquers, adhesives, latex detoamer in food-contact paper/pa-perboard food pkg. adhesives... 

Chem. Descrip. Manganese-based drier complex Uses Drier for urethane alkyd lacquers such as floor coatings, water-based coatings such as amine-neutralized resins, water-emulsifiable alkyds, and alkyd-actylics Features Cobalt-free... 

A urethane alkyd is an alkyd in which some of the dibasic acid is replaced by diisocyanate. The ester links are formed first in the usual way, the diisocyanate is added and the remaining hydroxyls are reacted at 80-95 C to form the urethane linkages (see p. 192). 

Urethane alkyds are basically similar to ordinary alkyds and may be drying or non-drying, long oil or medium oil. Short oil urethane alkyds are theoretically possible, but are difficult to make. Irreversible gelation tends to occur in the reaction vessel. 

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