Лако-красочные материалы — производство

We now know the primary functions of paints and coatings and their importance in enhancing and protecting many industrial and consumer products. Now let’s look at what paints and coatings are composed of. In general, paints and coatings are liquid mixtures that are applied onto the surfaces of products using a brush, roller or spray. These mixtures are supplied in a variety of forms, such as waterborne or solventborne, low viscosity or paste-like consistency, sprayable or brushable, to meet the end use application require­ments. Simply put, coatings are liquid mixtures that are spread onto a surface as a thin uniform wet layer that dries to a hard and adhe­rent film. After application, the wet liquid film is then converted to a dry and adherent coating through a physical drying or chemical curing process. The nature of the films formed depends upon the composition of the paint, and varies, for example from transparent to opaque, glossy to matte, and hard to soft.

Looking at the diversity of coating types, it is not surprising that different types of coatings would have different constituents. As one would expect, all coatings must have an ingredient that forms a film. These film forming ingredients, which are essentially poly­meric materials, are called resins or binders. Resins and binders have the capability of forming transparent and adherent films, but they cannot hide or destroy the surface on which they are applied. Pigments, which are finely divided insoluble particles, colored or white, have the capability of provided color and opacity when dis­persed into a medium. In general, a paint or a coating consists of pigment dispersed in a resinous binder, reduced to an acceptable application viscosity with a solvent, sometimes water. The role of the solvent is essentially to provide a suitable consistency to the pig — ment/resin mixture such that it can be applied uniformly as a thin layer using application equipment, such as a spray gun. In order to control some properties of coatings such as viscosity, drying time, opacity, storage stability and ease of application, some specialty che­mical compounds are added to the resin/pigment/volatile mixture, in small amounts, and are known as additives. A typical coating may have several such additives added to improve or modify specific properties. In general, all the ingredients of coatings are classified into the following four major raw material categories:

• Resins or binders

• Pigments

• Additives

• Solvents.