Basis Polyurethane

Curing the film in air can side reaction of isocyanate groups with water, leading eventually to the formation of urea linkages. The industry can be one and the same method to obtain different PU coating materials. For example, in the same pattern of production coatings, moisture curing, can be obtained on the basis of products alcoholysis of castor oil and glycerin, respectively, triethanolamine odnoupakovochnye dvuhupakovochnye and materials. To obtain two-component systems have found applications such as polyisocyanates, biuret-polyisocyanate how to cure without heating only in the presence of catalysts (octoate and naphthenate zinc). Coatings based on this have a lower hardness, but a good color - and weatherproof. The domestic industry produces aliphatic poliizo - cyanate, biuret based on hexamethylene diisocyanate and water.

But they do not mix, so the water injected into the mixture with a solvent (dioxane or acetone). In the commercially available two-component system consisting of semi-finished products of enamel and a polyisocyanate curing agent mixed before use. Semi-finished enamel - suspension of pigments and fillers, additives to the target in a solution of resin. Hardeners are available in sets. Relatively new type of polyurethane coatings are aqueous compositions that are growing application, staining wood, plastic, metal and other materials. Especially popular are water dvuhupakovochnye polyurethanes. They are ideally suited for corrosion resistant coatings on metal. The major consumers of such materials are the automotive, automobile repair sector, as well as manufacturers of military equipment that use dvuhupakovochnye polyurethane dispersion with a volatile content less than 180 g / l, allowing form a thermo - and chemically resistant topcoat for aircraft and tactical weapons. The most common type of water paint for wood is a mixture of polyurethane dispersions and acrylic latexes, hybrid akriluretanovye dispersion and composition based on akriluretanov with particles of the core / shell. When using polyurethane coating, it is necessary to take into account that the coatings are characterized by high akrilouretanovye resistant to water, acid rain gases, poliefiruretanovye - hardness and chemical resistance, although not withstand direct contact with liquid chemicals.