Лако-красочные материалы — производство

1. Modifying Resins

In a general sense, many resins can be utilised to modify the properties of acrylic resins. The main modifying polymers presently used include cellulose acetate butyrate, vinyl resins and nitrocellulose. These are used to alter the flow, gloss, sandability, hardness and flexibility of the cured film when utilised at the optimum level. However, with non-isocyanate acrylic resins, extreme care should be taken at the formulating stage, as the modifying resins can interact with the complex chemistry of these systems. For example, it has been shown that the modification of epoxy cured carboxylic functional acrylics with nitrocellulose (N/C) to enhance the drying characteristics of the film can also result in severe discolouration of the clear lacquer. This has been found to be due to the interaction of N/C with the amine functionality. On the other hand, resins which are unable to take part in the curing reaction will reduce the crosslink density and resistance characteristics of the final film. As with all new technologies, the coating formulator requires fully to evaluate the effect of modifying resins to ensure that unexpected side effects, such as the one stated above, do not adversely affect the properties of the coating.