Лако-красочные материалы — производство

Flooding and floating (Figure 5.4) is a defect that occurs in paint systems containing a combination of pigments that differ signifi­cantly in their wetting characteristics and particle sizes. It occurs after application in the wet film and is caused by segregation of the different types of pigments. This segregation is strongly influenced by flocculation of […]

All wetting and dispersing agents are chemically surface-active agents with a characteristic amphiphilic structure comprised ofone or more hydrophobic (lipo­philic) groups along with one or more hydrophilic (lipophobic) groups in the same surfactant molecule. Due to this structure, they tend to adsorb at the inter­face, which results in decreased interfacial tension. This is the key […]

In the absence of repulsive forces, freshly disrupted pigment particles would recombine (flocculate) in response to continuous collisions between them due to Brownian movement and attractive forces, such as London van der Waals forces, between them. The flocculation of pigment particles leads to gloss reduction, loss of opacity, poor color development, inconsistent color, and defects […]

Grinding involves the mechanical separation of agglomerates into primary particles, which is accomplished by providing mechani­cal energy through different types of grinding equipment, called grinding mills. Properly wetted particles are more easily disrupted into primary particles compared to agglomerates; therefore, wetting agents help grinding indirectly.

The process of dispersing pigment particles in a vehicle involves a combination of three distinct phenomena called wetting, grinding and dispersion. 5.2.1.1 Wetting The pigment used in the coating is supplied in the form of agglome­rates (Section 3.2.2.3). The process of wetting involves displacement of air and moisture from the surface of the pigment by […]

Wetting and dispersing agents are additives that aid the incorporation of pigments and extenders in the paint. Pigments are an integral part of the paint that govern different aesthetic, performance and functional properties of the coating, as described in Section 3.1.1. For maximum effectiveness of pigments in imparting these properties, their homo­geneous distribution in the […]

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 […]

Being a volatile component of coatings, all solvents inevitably eva­porate into the atmosphere. The presence of organic compounds in the atmosphere can lead to serious problems related to air pollution. These solvents have been termed VOCs. When emitted from paints and accumulated in the troposphere, VOCs can react with oxygen in presence of nitrogen oxides […]

It is evident that many solvents present considerable health hazards and hence have been subject to restriction through regulation. Even when using solvents of low toxicity, their odor may be undesirable in both the working environment and in the area around manuf­acturing facilities. The common modes of entry of these volatile substances in the body […]

4.4.3.1 Chlorinated hydrocarbons Chlorinated hydrocarbons have higher solvency than correspon­ding hydrocarbons for most resins and polymers used in coatings. They are miscible with many other types of organic solvents, but are insoluble in water. Non-flammability and high specific gravity are unique characteristics of this class of solvents. In recent years, their use in coatings has […]