Paint additive is an indispensable component of coatings. It can improve the production process, maintain stable storage, improve construction conditions, improve product quality and give special functions. Reasonable and correct selection of additives can reduce costs and improve economic benefits.

Paint additives are categorized by use and their role

1.Drier

A kind of substance which can accelerate the drying of the coating film can promote the absorption of oxygen and the polymerization of double bonds in the dry oil film. It can shorten the drying time of oil film from several days to several hours. It is convenient to construct and can prevent contamination and damage to Undry film.

The oxides, salts, and soaps of many metals have the function of drying, but the useful ones are lead oxide (red Dan, yellow Dan), manganese dioxide, lead acetate, lead nitrate, manganese sulfate, manganese chloride, manganese borate, manganese acetate, cobalt acetate, cobalt chloride, naphthenic acid soap of lead, cobalt and manganese, linoleic acid soap and rosin soap.
Because soap drier has good oil solubility, it has high drying efficiency. In modern paint industry, naphthenic acid soap is often used as drier. Naphthenic acid soap is usually produced by double decomposition.

The amount of drier in oily coatings depends on the amount of dry oil or semi-dry oil. Taking dry linseed oil as an example, the amount of lead drier (measured by lead) is 0.4-0.5% of the oil quality; the drying capacity of cobalt and manganese is stronger than that of lead, and the ratio of cobalt, manganese, and lead is about 8:1:40. Two or three metal soaps have synergistic effects. In resin coatings, the dosage of drier should be increased.

2.Tougheners

That is plasticizer (see plastic additives). The common varieties of coatings industry are diethyl phthalate, dibutyl phthalate, dioctyl phthalate, tributyl phosphate, triphenyl phosphate, trimethylphenyl phosphate, and some special varieties.

3.Thickener

Material that can improve the viscosity of coatings and reduce their fluidity. The important purpose of using thickener is to reduce the flowing phenomenon in finishing. Thickeners used in coatings are mainly as follows: 1. white carbon black; 2. bentonite and organic bentonite (bentonite treated with cationic organic matter); 3. surface treated activated calcium carbonate particles; 4. hydrocastor oil; 5. metal soaps, such as calcium stearate, aluminium stearate, zinc stearate; 5. polymerized vegetable oil and fatty acid dimerization. The ester of polyols and solvents.

4.Pigment dispersant

Used to prevent the deposition or floatation of pigments. Bentonite and organic bentonite, metal soap, hydrogenated castor oil, and other thickeners can play the role of pigment dispersant. Surfactants, low molecular weight polyethylene oxide (polyethylene oxide), low viscosity methyl silicone oil, lecithin, and its derivatives are also commonly used.

5.Leveling agent

A substance that helps to form a smooth finish. Substances that can reduce the surface tension of coatings generally have the function of leveling agents. The leveling agents used in industry include fluorine-containing surfactants, polyacrylates, and polyvinyl butyral. Organosilicon leveling agent is generally used to control short-wave leveling and reduce surface tension obviously, while acrylate leveling agent is used to control long-wave leveling and reduce surface tension slightly.

6.Anti-Skin Agent

Substances such as methyl ethyl ketone oxime and cyclohexanone oxime that prevent the surface crust of oily coatings in use.