Лако-красочные материалы — производство

Unlike most other resin systems, polyurethane resins, in most cases, are not supplied to coating formulators, but rather their com­ponents — polyols and isocyanates — are supplied. Coating formulati­ons are made using these components, and in most cases, urethane linkages (polyurethane resins) are produced during the curing process. This offers a great deal of freedom […]

Polyols are materials with hydroxyl (-OH) groups. Polyols are very important components of polyurethane resins and control many mechanical, thermal and physical properties of their coatings, besides the overall cost. Like isocyanates, polyols for polyurethane resins include monomeric polyols and polymeric polyols (Figure 2.62). Polyols with primary — OH groups are more reactive with isocyana­tes […]

Two types of isocyanate compounds, differing greatly in their reac­tivity, coating performance and cost, are (a) aromatic isocyana­tes and (b) aliphatic isocyanates. Aromatic isocyanates have much higher reactivity with active H-compounds than aliphatic isocya­nates. Polyurethane coatings based on aromatic isocyanates suffer from poor resistance to sunlight exposure (poor UV resistance), poor gloss retention and significant […]

Polyurethanes are an increasingly important type of resins finding applications in virtually all types of coatings due to their versa­tility and excellent performance properties. Polyurethane resins are polymers containing urethane (-NH-CO-O-) linkages, usu­ally made by reaction of compounds containing isocyanate groups (-NCO) and hydroxyl groups (-OH). 0 R—N=C=0 + HO-R’ ————————— — R—NH—C-O—R’ Isocyanate Alcohol […]

Polyimides (Figure 2.58) are typically prepared by reacting a tetracarboxylic acid anhydride such as pyromellitic dianhydride with aromatic diamines such as 4,4’-diaminodiphenylether. Heat resistance of greater than 250 °C during continuous exposure can be obtained using coatings based on such binders. Polyimides are thermoplastics that are difficult to dissolve and are therefore used as a […]

Non-reactive polyamide (thermoplastic) resins are higher MW (up to 10,000 g/mol) condensation products of dimer fatty acids and diamines. Such resins are important binders for liquid inks. In the synthesis of these resins, both dibasic acid and diamine components are blended at medium temperatures and reacted until the water of reaction can be distilled off. […]

Reactive polyamide resins are typically prepared by condensation of dimerized fatty acid with excess equivalents of aliphatic diami­nes. Reactive liquid polyamide resins are designed primarily for use in two-component epoxy-polyamide coatings and adhesives. Gene­rally, reactive polyamide resins are supplied as either very viscous liquids or viscous solutions in organic solvents. In reactive polya­mides, monofunctional fatty […]

Polyamides are polymers with amide linkages (-NH-CO-) in their backbone structures. A well-known example of this type of polymer is nylon, the condensation product of an aliphatic dicarboxylic acid with aliphatic diamines, which was originally developed for replace­ment of silk. Very high MW and poor solubility of nylon makes it unsuitable for coating applications. Polyamides […]

In water-reducible waterborne epoxies, acidic or basic functionali­ties are introduced into an epoxy polymer, which upon respective Figure 2.57: Important routes for water-reducible epoxy resin neutralization with a fugitive base or acid, generates an ionic group that renders it water reducible (Figure 2.57). Acid functionalized epoxy resins are generally prepared by este­rification of epoxy resin […]

Type II waterborne epoxy systems are based on solid epoxy resins in the form of uniform aqueous dispersions containing co-solvents and stabilized by emulsifiers. These systems can be prepared by direct emulsification involving dispersion of epoxy resin (a solution in co-solvent) in water using an emulsifying agent (surfactant). These systems can also be prepared by […]