Types of water-based paints

2022-05-09   Pageview:508

Water-based coatings can be divided into types according to the following aspects: ① type of binder; ② drying method; ③ application field.

A more definite method is to consider the stable state of different binders in water, and divide them into “true solutions”, colloidal solutions, dispersions and emulsions.

Generally, water-based coatings can be divided into three types: solution coatings, colloidal solution coatings and emulsion coatings according to the relationship between their binders and the water phase.

The binder contained in the water-based paint is divided into two cases: one is that its structure has strong polarity, and the characteristics of the structure make it soluble in water or swell in water; the other is to generate a binder through a chemical reaction. the salt into a water-soluble state. Water-soluble binders can generally be divided into nonionic, anionic, and cationic types.

Commonly used monomers: acrylates, methacrylates, styrene, vinyl acetate, ethylene, butadiene, vinyl chloride and other vinyl esters.

Commonly used emulsion resins are: alkyd resin emulsion, epoxy resin emulsion, silicone resin emulsion, asphalt emulsion, etc.

Among them, the hydrogels of modified alkyd resins and epoxy resins are particularly important. Various forms of dispersions and emulsions have the properties of a general two-phase structure and can be divided into dispersed phase and continuous phase, namely solid-liquid or liquid- liquid. When the thermal motion energy of the particles is less than the sum of the energy of the electrostatic repulsion force and the van der Waals attraction force, byk additives for coatings, the liquid is in a stable state, and this balance must be carefully maintained in order to ensure that the binder and water-based paint system do not flocculate. The following factors are important factors for the occurrence of flocculation: ① acid;② salt; ③ water-soluble substances (such as solvents); ④ colloids with opposite charges; ⑤ heat; ⑥ freezing; ⑦ high shear force or pressure; ⑧ water Evaporation; ⑨ current. Among all the above process influencing factors, the influence on the stability of the liquid is the most important.

In addition to the stability of the dispersion mentioned above, the stability of the paint film after the coating is formed is equally important. These include the coating’s water resistance, durability, resistance to various chemicals, and resistance to ultraviolet light (UV).

At this point, the basic principles of drying solvent coatings apply to waterborne coatings, which can basically be divided into the following categories.

① Physical drying Moisture, amines (anionic binders) and acids (cationic binders) volatilize, sometimes including auxiliary solvents;

② Oxidative drying Cross-linking is caused by oxygen;

③ Thermal cross-linking (baking enamel) heating leads to condensation and cross-linking of self-functional groups or condensation and cross-linking with cross-linking resin.

Due to the different drying principles and processes of coatings, coatings have the following two forms:

① One-component coatings, that is, one or more binder components in the coating formulation can be mixed together for stable storage;

② Two-component or multi-component paint.

Due to the short storage time (service life) of the binder components after mixing, they must be formulated according to the ratio before use.


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