Лако-красочные материалы — производство

5.1 Introduction

Resins or binders, pigments and extenders, and solvents are the major components of coatings by mass, which expectedly govern the major properties of these coatings. However, most coating compositions also contain components called additives. Additives may directly influence the coating properties or may modify the properties of the major ingredients.

Anything in a coating formulation that is not a resin, pigment or solvent may be considered an additive. Due to their vast variety and differing chemical compositions and mechanisms of action, it is difficult to provide a clear definition for additives, though they have been described according to DIN 55 945 A1 as follows: “An additive is a substance added to a coating material in small quantities in order to impart specific properties to the coating material itself or the coating films produced from it.” We can compare the role of addi­tives in coatings to that of spices in food, in which a small amount of a specific spice may have profound influence on flavor.

Some of the important generic considerations and remarks for using additives are:

• Some additives are very product specific, so that they are effective only in certain systems while completely ineffective in others.

• The use of additives frequently leads to some undesirable side effects; therefore, the best policy is to use the minimum number of additives in the minimum amounts needed to achieve desired properties. The idea is to avoid a spiral formulation, meaning that use of one additive generates side effects that lead to the need to add another type of addi­tive to resolve them, which may result in another side effect.

V. Mannari, C. J. Patel: Understanding Raw Materials © Copyright 2015 by Vincentz Network, Hanover, Germany ISBN: 978-3-86630-603-5

• The effects of additives can be so dramatic that careful selection of additives and their usage levels are extremely important, toge­ther with a good understanding of the potential interactions with other ingredients.

• Because most additives are used in small quantities, extreme care must be taken in their calculation, weighing and addition.

Additives are much too diversified to be classified according to their chemical nature. Therefore, even though many additives are multi­functional, most suitably, they can be classified according to their functions. The most common types of coating additives will be descri­bed in this chapter according to their functional role in coatings.