Лако-красочные материалы — производство

As mentioned above, both thermoplastic and thermosetting type acrylic resins are commercially available for coatings, elastomers, sealants and adhesive applications. These resins are supplied in many different delivery forms such as powders or pellets, solutions in organic solvents and aqueous dispersions. These resin types are briefly described below.

Acrylic resins are generally prepared by radical initiated chain — growth polymerization. As mentioned earlier in this chapter, chain — growth polymerization allows for preparation of polymers with very high MWs, of the order of a few hundreds of thousands of grams/ mole. Acrylic resins with such high MWs are generally capable of forming useful […]

Acrylic resins, also known as acrylates or polyacrylates, are an impor­tant class of versatile resins used in a wide variety of architectural, industrial and specialty paints and coatings, sealants, adhesives, and elastomers. In general, their excellent resistance to sunlight exposure and water make them especially suitable for a number of end-use applications. Acrylic resins are […]

Amino resins, being thermosetting materials, can self-polymerize, but this results in a transparent but very hard and brittle polymer network that is not useful for coatings. Therefore, since their intro­duction, aminoplasts have been used as cross-linking agents for pri­mary film forming resins such as polyesters, alkyds, epoxies, epoxy esters and acrylics. Aminoplasts are predominantly used […]

A large variety of melamine resins are commercially available, with important variables being type of amino compound, molar ratio of formaldehyde to amino compound, degree of polymerization, type of alcohol used for etherification and degree of etherification. Based on the type of amino compound, the aminoplasts used in coatings are classified as four main types: […]

The term amino resins is used to describe a very important and versatile group of thermoset polymers derived from nitrogen-con­taining compounds, most typically, melamine and urea. Amino resins (also known as aminoplasts) are widely used in a number of non-coating thermoset applications. In coatings, they are used mainly as cross-linkers, and not as primary film […]

Phenolic resins of both types — novolacs and resoles — are frequently chemically modified to improve their mechanical properties and to make them more suitable for coating applications. Rosin modi­fied phenolics have been widely used in oleoresinous varnishes and printing inks. They are prepared by reacting resole type phe­nolics (~10 to 20 % by weight) […]

Novolacs are phenolic resins prepared under acid catalyzed condi­tions with a molar excess of phenol (f:p <1), see Figure 2.21. Acids such as oxalic acid, sulfuric acid, hydrochloric acid, formic acid, and aromatic sulfonic acids are used as catalysts. In contrast to resoles, here the methylolated phenol molecules are rapidly polymerized through methylene linkages rather […]

Resoles are produced by a base catalyzed reaction between phenols and formaldehyde with a molar excess of the formaldehyde (f:p > 1), see Figure 2.19. Methylolated phenol is more reactive than phenol; therefore, once the reaction starts, the reaction accelerates in a short time. A higher molar excess of formaldehyde increases the reaction rate but […]

Formaldehyde reacts with phenol by electrophilic substitution at the 2-, 4- and 6-positions of phenol and will subsequently condense, forming a densely cross-linked network. This reaction can be cata­lyzed by acid as well as base catalysts. The nature of the product obtained is largely dependent on the type of phenol, the molar ratio of formaldehyde […]