Лако-красочные материалы — производство

The performance properties of thermosetting coatings, which rely on a chemical reaction between different functional groups to give a cross-linked polymer network, are dependent on the extent of the cross-linking reaction and hence the cross-link density. Similarly to other organic chemistry reactions, cross-linking reactions may be significantly accelerated at higher temperatures or by the use […]

Some thermosetting binders, such as resins based on drying oil modified resins, like alkyds and epoxy esters, are cured by a cross­linking reaction that is triggered by the diradical and atmospheric oxygen; this is commonly known as oxidative or autoxidative curing. The first step in the cross-linking reaction is oxygen uptake by the film and […]

For thermoplastic binders, film formation occurs merely through evaporation of the volatile solvent or water. In the case of thermo­setting binders, the extent of chemical cross-linking is an important factor influencing their mechanical and performance properties. Catalytically active additives are used in such systems to acce­lerate cross-linking reactions. In the subsequent chapters, some commonly used […]

Adhesion is a key property of coatings and can influence many other mechanical and performance properties. Adhesion can be defined as the resistance of the coating film to mechanical separation from the substrate. While the nature of the binder is the primary factor influencing adhesion, it can be improved by the use of additives called […]

In many applications, satin or low-gloss finishes are preferred over high-gloss finishes for reasons such as having an elegant and luxu­rious appearance, hiding imperfections of a large surface area or even safety reasons, such as on the dashboards of cars. Reduction in gloss can be achieved by increasing PVC or by introducing incom­patibility into the […]

Slip is a term used to describe the smoothness, feel and slipability of a coating surface. It may also be related to the friction or lubricating aspect (feel) of the coating surface. Mar resistance is the ability of the coating to withstand mechanical abuse, such as abrasion. In many practical circumstances, an additive that provides […]

Mechanical properties such as hardness, scratch resistance and mar resistance of the coating surface as well as the surface slip are mainly defined by the binder of the system; use of additives makes it possi­ble to control such surface characteristics independently from the coating binder. The gloss of the coating is one of the important […]

Solventbased paints have significantly lower surface tension than aqueous paints. Mineral oils are not useful as defoamers for such paints, and therefore, silicone defoamers are widely used. Pure poly — dimethylsiloxanes with MW 10,000 to 100,000 can be used as defo­amers. Their compatibility is an important consideration, as they can cause surface defects such as […]

Defoamers are mainly composed of active compounds, spreading agents and carriers. Spreading agents are surfactants that help in reducing the surface tension, while carriers are the solvents used to compound the other ingredients. Defoamers for waterbased coatings The main groups of defoamers for waterbased coatings are: mineral oilbased defoamers, silicone defoamers and fluorinated defoamers. Mineral […]

An effective defoamer must counteract the foam stabilization mechanism. Defoamers are low surface-tension liquids that have a controlled insolubility or incompatibility in the system to be defo — amed, along with positive penetration and a positive spreading coefficient. When they enter the foam lamella and spread across the interface, the stabilizing surfactant molecules are displaced, […]