Лако-красочные материалы — производство

In order to find a safer non-flammable alternative to nitrocellulose, cellulose esters of lower organic acids have been developed and commercialized.

Cellulose acetate is prepared by reacting cellulose with acetic acid or acetic anhydride in the presence of a catalyst. Cellulose acetate has low flammability and better weathering resistance, but is of little interest as a binder for coatings due to its limited solubility and sensitivity to hydrolysis.

Cellulose acetate butyrate is an important cellulose ester deriva­tive used in the coating industry. Chemically it is a mixed ester of cel­lulose with acetic and butyric acid. Residual hydroxyl groups and the ratio of butyrate to acetate groups are the main structural variations along with MW for various grades of cellulose acetate available on the market. Because of the bulky substituent (butyric acid), the regula­rity in the molecule decreases and spacing between cellulose chains increases, resulting in better solubility and improved compatibility with other binders and plasticizers. Bulky group substitution also ren­ders flexibility and better moisture resistance. The residual hydroxyl groups of cellulose acetate butyrate resins can also react with other binders used in the composition. Cellulose acetate butyrate has seldom been used as sole binder, but rather is blended with other resins to balance the properties. It is used in clear and pigmented coatings for different substrates including metal, wood, paper and plastic. Some important applications of cellulose acetate butyrate are as an additive in automotive coatings and wood finishes, to increase solvent release and viscosity buildup, and for flow control, sag control, minimizing cratering and orange peel, and good hardness development. In auto­motive metallic basecoats, cellulose acetate butyrate assists in consi­stent orientation of metallic flakes as well as resistance to redissolving upon application of a subsequent coat. Cellulose acetate butyrate is also useful for better pigment dispersion in automotive coatings, pro­viding consistent dispersion of multiple pigments (anti-floating). It also has good UV stability and is known to provide better intercoat adhesion. In wood coatings for furniture, cellulose acetate butyrate is used for its durability, non-yellowing properties, stain resistance, reduced picture framing and better optical properties, including gloss and distinctness of image. It also finds applications in advanced coil coatings and printing inks due to the properties listed above.