Лако-красочные материалы — производство

Chemically, cellulose is a natural polysaccharide with a high MW, linear structure having repeating anhydroglucose units. It is mainly amorphous but also has considerable crystallinity, making raw cel­lulose insoluble in organic solvents and water. Because of this inso­lubility, cellulose finds no applications in coatings in its unmodified form. To render solubility, it must be chemically […]

Ethyl silicate is a clear liquid derived by reacting silicone tetrachlo­ride with ethanol. In the coating industry, it is useful as a binder in zinc-rich primers, one of the important layers in many protective coating systems. The partially hydrolyzed solution of ethyl silicate is one of the two components in the system, with the second […]

In keeping with the global trend, waterbased silicone resins are also commercially available for the coating industry. Some important com­mercial categories of waterbased silicone resins are primary emulsi­ons, secondary emulsions, and waterborne silicone modified resins. Primary emulsions are prepared by polymerization of low MW cyclic siloxanes in combination with branched silicone resins or often with […]

Silicone modified resins differ from silicone resin blends in that they are chemically reacted with hydroxyl functional organic resins to obtain copolymerized products. Because of their high cost and long curing cycle at high temperatures, pure silicone resins have limited application in coatings. Copolymerizing with organic resins expands their usability in coatings by improving ease […]

Conventional silicone resins have either alkoxy siloxane (-SiOR) or silanol (-SiOH) functional groups, which limits their application to certain specific curing chemistries. To expand their scope in coa­tings, modified silicone resins have been developed with functional groups suitable for conventional curing chemistries. For example, the — SiOH group of silicone resin, being acidic, does not […]

Classical silicone resins have limited compatibility with organic resins, but some specially designed high-phenyl content silicones have good compatibility with other organic film formers. In general, organic film formers contribute to quick-drying (dry to handle) characteristics, hardness and abrasion resistance, while silicones improve weatherabi — lity and heat resistance. Commonly used organic binders for blending […]

Curing reactions of silicone resins essentially involve continuation of the condensation reaction used during their preparation. They need a higher temperature of 225 to 250 °C or more for curing. By using an oil-soluble organometallic catalyst such as zinc octoate, the curing temperature can be reduced.

Most silicone resins are copolymers of methyl and phenyl substi­tuted monomers. Based on the type of organic substitution, the two main types of pure silicone resins are high-methyl silicone resins and high-phenyl silicone resins. High-methyl silicone resins are polymethylsiloxanes that have methyl groups as the predominant organic substitution and hence have the lowest carbon content. […]

The classical pure silicones are made from hydrolysis of RSiX3, R2SiX2 and R3SiX, where R, in most cases, is methyl, phenyl or a mixture of both. If only methyl substituted “D” units are used, with few “M” units as chain stoppers, extremely nonpolar polydimethylsiloxanes, com­monly known as silicone oils (Figure 2.70), are obtained. Their viscosity […]

In contrast to most organic polymers, in silicone resins (also called silicones or polysiloxanes), the backbone is made of silicon and oxy­gen, with organic groups substituted as side chains on this backbone. Thus, the skeleton of silicones is related to silica and silicates, but some of the oxygens are replaced by organic groups. The most […]