Coating film type and film forming mechanism

Paint is a non-volatile part and volatile part of the two parts of the coating applied to the surface of the object, its volatile part gradually dispersed, the rest of the non-volatile part is left on the surface of the object dry film: these non-volatile solid parts are called coating film-forming substances, film-forming substances can be divided into the main film-forming substances, secondary film-forming substances and film-aiding substances. See figure below:
, the type of coating film
according to the molecular structure of the coating film do not ask. The coating film can be divided into two categories, namely, the coating film of the low molecular spherical structure, the coating film of the line molecular structure and the coating film of the mesh molecular structure of the body type, see Figure
II, the film-forming machine of the coating
It is called the film - forming process of the coating or the curing of the coating. Commonly referred to as coating drying.
coating mainly depends on solvent evaporation, melting, shrinking, polymerization and other physical or chemical effects into a membrane, its components and structure are

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of commonly used coatings mainly include physical drying and chemical drying.
(i) Physical process drying
physical drying is only by evaporation of liquid (solvent or dispersion phase) in the coating to obtain a drying process of the dry hard coating film a coating drying film process.
1. Soluble hair paint
solvent hair paint paint is played by the coating of small solvents and dried into a paint film. Its drying film process is as follows: When a polymer coating is applied to the substrate, the solvent molecules in the coating diffuse outwards from the coating, the diffusion rate with the coating curing, the resistance gradually increases and slowly decreases, the solvent molecules that have been waved form a layer of gas on the coating surface. Finally the solvent molecules spread out of the gas layer and out.
throughout the evaporation process, as the solvent continues to evaporate, polymer molecules gradually become closely connected with their concentration, and finally the polymer is very tightly stacked to form - a uniform and continuous coating film. Solvent-waved paint can evaporate in vain at room temperature to achieve a dry state, but heating up can speed up the drying speed.
2. Emulsions and coatings
When the emulsion-type coating is applied to the surface of the object, the polymer droplets (dispersed phase mass points) accumulate more and more closely as the continuous phase (dispersion medium) is gradually volatile, until contact occurs with each other However, what is obtained at this time is only a polymer mass of the non-continuous film, in the gap between the mass points also contains some liquid, it is necessary to make the mass between each other, so that the interface between the mass disappeared, so as to obtain a continuous homogeneous coating film. The following three film-forming methods of latex paint can do this.
(1) a drying latex paint with a wire polymer as a film-forming substance, which, when the temperature increases, allows the polymer molecules in the non-continuous polymer mass to move freely and be connected to a uniform coating film;
(2) to the lower glass temperature of the wire polymer as a film material latex paint, its glass transformation temperature can be below room temperature, its coating film must be quite soft, or the glass temperature of the wire polymer is not low, but if there is plasticizer or high boiling point solvent. The result is latex paint that increases polymer fluidity. The high boiling point solvents (or plasticizers) added to these latex lacquer paints are compatible with continuous, which promotes the polymer's cohesion (the process of flattening between polymer dots is called bonding). In continuous phase volatility, the gap between the mass points left a condensed solvent, these condensed solvents penetrate into the mass, so that the mass has a greater fluidity and gather with each other, in the film after a period of time, the polysumed solvent gradually evaporated;
(3) contained in the film after. Latex paint of low molecular weight substances (crosslinkers) that can be cross-cured by chemical reaction at Bao temperature or above room temperature.
physical process drying is also known as hair drying, with this kind of process into a film coating called hair paint. Hair paint into the film does not accompany the chemical reaction, so the formation of the paint film can be re-dissolved or hot melt and has thermoplastic properties, and therefore called thermoplastic coating.
(ii) chemical process drying
chemical process drying its film-forming process is mainly shrinking, polymerization and other chemical effects. We can line-type or mildly branched chained polymers, even with simple low-molecular compounds to make coatings, to be applied after coating construction, and then cross-linking reaction, become solid mesh structure of polymer compounds, the formation of the coating film can no longer be dissolved by solvents, heat can not melt, so this type of coating is also called thermo-solid coating. These coatings vary according to the chemical reaction of the film - forming process. It can be divided into the following types of coatings.
1. A polymeric compound
a mesh structure formed by a shrinking reaction, and a coating consisting of a compound as a substing is called a compacted coating. In order to bit the reaction between the compositions of such coatings only begins after coating construction, to avoid premature chemical reactions, the non-reactive compositions can be packaged in different containers or two or more compositions, late paint before use before mixing them. Epoxy resins and unsaturated polyseed and thick coatings fall into this category.
2. Polymerized coatings
coatings that form polymer compounds by polymerization reaction are called polymerized coatings and belong to this type of coating, synthetic resin coatings with unsaturated monosomes or unsaturated low molecular resins as the primary primary shaking. The unsaturated base of this coating, by triggering a free-form reaction and crosslinking agents (such as styrene, etc.), to produce a mesh structure of polymer compounds. For example, acrylic wall coatings, etc.
3. After the construction of the coating
coating that reacts with the air, the polymerized polymerization reaction occurs in contact with oxygen in the air and forms a mesh structure of the polymer compound, which is composed of a coating made up of this compound called an oxidizing polymer coating. Belongs to this type is based on the main raw materials of oil and oil-based toned paint.
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