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Standardize The Use Of Coating Terms


At present, China's coating industry in the definition of some terms and the use of confusion, in order to facilitate learning, scientific research and accurate understanding, it is necessary to put forward some suggestions for the industry reference.

1. Paints, oil-based coatings, oil-based coatings
Paint: paint is the earliest name of paint in China. The ancient preparation of paint is mainly made of tung oil and lacquer, so the paint is called paint. Later, many paint factories in China to paint (paint) named, such as, Beijing Red lion paint factory, Shanghai Zhenhua paint factory, Guangzhou paint factory, etc. So in our country paint is paint, paint is paint. Although the meaning of the word is not very accurate, but this is history, there are also two foreign corresponding terms coating and paint exist, still widely used interchangeably.

Oil-based coating: it is the coating of main raw material with natural vegetable oil, oil passes refining or the coating that adds resin calls oil-based coating, or say oil-based paint, because its performance is poorer, dosage is very few now. But if alkyd paint is counted as oil-based paint, it is another matter.

Oil coating: In surface chemistry, the difference in the surface tension of the oil and water, especially the water's surface tension is very high, so commonly used as a reference parameter, which has a hydrophilic, hydrophobic terms, and hydrophobic is often referred to as oil wet, which derived from oil and water, it is to the distinction between a rough idea of the material surface tension, and other properties of the material, such as, volatile, toxicity no relationship at all. According to the above statement, now the coating, in addition to water-based coating, in a certain sense can be called oily coating, including oil based coating, high solid points coating, radiation curing coating, even powder coating. It is wrong for some people to equate oily coatings with solvent-based coatings.

2. Solvent-based coatings, water-based coatings and so-called "water paints"
Solvent - based coating refers to the coating with organic solvent as dilution medium (solvent or dispersion medium), and water - based coating is water as dilution medium coating. Somebody calls waterborne coating now "water paint", juxtapose it and paint and stand in opposition, this is very wrong. As mentioned before, the paint is synonymous with coating in China, not short for solvent paint, it also includes the water-based paint, water-based paint can be called a water-based paint, in addition, on the meaning of the connotation of it, water paint and paint can not coordinate, the CPC and paint, paint film forming matter, and water is a water-based coating dilution medium, not film-forming material, Should not be compared with film - forming material "oil".

3. Water soluble coating, water dilutive coating
As mentioned above, the coating that is solvent or dispersing medium with water collectively is water borne coating, basically divide into two kinds: water soluble coating and water dispersing coating. Water dispersive coating can be divided into emulsion coating, latex coating and water can be diluted.

Water-soluble coating: coating with film soluble in water, such as polyvinyl formaldehyde for film soluble coating; High carboxyl content of polymers, such as, acrylic acid mole fraction of more than 30% of polyacrylic resin for the film of water-soluble coating, because of its hydrophilic groups too much, water resistance is very poor, the actual has rarely used. It is wrong to call the polyacrylate water-based coating with low acrylic acid content water-soluble coating, it is a small particle size dispersion, because of the appearance and water-soluble system is very similar, and is miscalled water-soluble, this situation has been gradually corrected.

Water can dilute the coating: also known as two disperse coating, usually it is film-forming substance first in the solvent polymerization and become, monomer generally contains a certain amount of carboxyl, after polymerization is completed with amine neutralization, make the carboxyl polymer into salt, and then add water dilution to the required viscosity. In the process of dilution, the polymer self-aggregates into dispersed particles, and the carboxyl group becomes the protective group toward the water phase, so it can be considered as self-emulsified into dispersed particles. Its dispersions are transparent, sometimes blue, and similar to aqueous solutions, so they were once misnamed water-soluble coatings.

4. Emulsion, latex, emulsion
Emulsion and latex are both emulsions, but they are different in substance. Emulsion is a liquid dispersed in water, that is, the particles in the dispersion system are a hydrophobic liquid, while latex is a solid dispersed in water, and the particles in the dispersion system are solid. Both are emulsions, but they are identical in appearance.

The most commonly used polyacrylate emulsion in coating, is to add monomer in water first emulsifier stirring, emulsifying all kinds of acrylic monomer emulsion, and then through polymerization (emulsion polymerization) reaction, become latex. The distinction between the two is very clear and not easily confused. It is a great pity that many people in China's coating industry do not distinguish the two concepts, some standards, documents, grades are called latex latex, these mistakes for teaching and understanding the characteristics of latex brought a lot of trouble. This article lists several questions that are difficult to answer without proper names.

(1) The raw material of emulsioni paint is commonly known as emulsion, emulsion added with pigment or additives, how to become emulsioni paint? No logic.
(2) the liquid particles in the emulsion will meet the natural fusion, why to add film additives?
(3) Some solid particles in latex can be designed to form core-shell structure or polyphase structure. Is there core-shell structure in emulsions?
(4) Now that real emulsion paints have been developed, how do they be defined? How to distinguish with emulsioni paint?
(5) In the journal, often see the title of "XX acrylate emulsion synthesis" paper, acrylate emulsion need synthesis? Add an acrylate monomer to water with an emulsifier and stir it to make an emulsion, which everyone knows how to do.

The confusion phenomenon in the use of coating terms has been greatly improved in China. But the problem of emulsion and latex is not divided, some standards, brand, advertising used the wrong term, businesses are unwilling to change, afraid of losing customers; Leading departments do not want to change, afraid of trouble, technical personnel to push the boat. But we think, with the improvement of our coating research level and academic level, we should be more rigorous in science and technology. Because this kind of confusion has brought many troubles to teaching and basic research, it should be put right as soon as possible. If there is a mistake, it should be corrected. Academic rigor should be a good quality for scientific and technological personnel.