General coating consists of film-forming substances, solvents, pigments, additives and fillers. Filler is the largest component of coating except film-forming material, so the selection of filler is very important for the performance of coating. Shanghai Innovy Chemical New Materials Co.,Ltd is a reliable factory in China for all kinds of painting fillers.
The main functions of fillers in coatings are as follows:
1. Improve the mechanical strength of coating and film coating;
2. The use of filling can increase the content of solid substance, reduce the required amount of resin and solvent, and thus reduce the cost;
3. Endow the coating with good fluidity and construction performance, and increase the film thickness;
4. Provide partial covering, weather resistance and UV resistance, and prolong the service life of the coating;
5. Special functions, such as UV shielding, heat resistance and minimal toxicity;
6. Improve the performance of other additives, such as thickener, rheological agent, antistatic agent, UV stabilizer, etc.
Fillers such as calcium carbonate, talcum powder, kaolin, etc. have different composition, structure and chemical properties, but they all have common characteristics, which are necessary for coating fillers:
1. White or light color, and the whiteness is generally more than 90%;
2. Small particle size, narrow particle size distribution, easy to disperse, can completely and evenly cover the coating;
3. It is necessary to have low oil absorption property and low oil absorption value to improve the critical pigment volume concentration of the paint, save resin base material and meet the requirements of modern high solid paint.
4. It can make the coating have good rheological properties (fluidity, leveling, suspension, thickening, etc.), make the coating not precipitate during storage, facilitate the construction of film, and form a smooth and smooth film;
5. Good compatibility with other components of the coating and no chemical reaction with other components;
6. Have appropriate specific surface area, particle shape and crystal shape. It directly affects the viscosity, dispersion stability, refractive index and other properties of the coating.
According to the function of fillers in coatings, fillers are generally divided into ordinary fillers, active fillers, functional fillers and special fillers; according to the composition, fillers can also be divided into carbonate, silicate, sulfate and oxide, etc.
Different fillers tend to have different effects. There is a saying to describe three fillers with the largest dosage: calcium carbonate reinforcement, talcum powder toughening, barium sulfate polishing. This is a general conclusion, but it points out the different unique features of the different fillers.
1. Calcium carbonate
Calcium carbonate is the most commonly used filler for coatings. It is also widely used in plastic industry, paper industry and so on. Calcium carbonate has good weather resistance, high strength, low price (the common coating filler is the lowest), wear resistance, which can improve the corrosion resistance and rheological property of the coating, reduce the pulverization rate, improve the color retention and improve the anti pollution performance. The disadvantage is that it is easy to get white frost.
Talcum powder is also called hydrous magnesium silicate, which is directly crushed by talcum. It has good lipophilic property. It is easy to disperse in solvent based coatings and will not form caking precipitate. It is the main filler of solvent based coatings. However, it is easy to cause caking precipitate in water-based coatings, so the amount is less, because it has strong oil absorption and is not commonly used in powder coatings. Talc powder is basically fibrous or flaky, with good weather resistance, but poor fluidity in the coating, and insufficient film flatness; flaky talc powder can improve the leveling, film flatness and light retention of the coating. Its chemical property is extremely stable and it can withstand 900℃ high temperature. Its disadvantage is easy to pulverize, so it should be used appropriately.
The appearance is a dense white powder with a density of 4.5g/cm3. The ground barite powder is widely used in industrial primers, especially automotive primers, as well as topcoats that need high gloss. Micro barite powder can partially replace titanium dioxide in latex paints. It has the advantages of low oil absorption, high density, good filling performance, good gloss and light retention, high chemical inertness, acid resistance, alkali resistance and light resistance. It has great value in high corrosion environment. Compared with barite powder, precipitated barium sulfate has smaller particle size, higher price, and is easy to settle. It is an important filler of high gloss semi gloss powder coating.
It is also called Baiyun soil, guanyintu and taotu. It is named after Kaolin village, Jingdezhen, Jiangxi Province. It can be divided into two types: water washed kaolin and calcined kaolin, which are flake or tubular, with good covering and suspension. Water washed kaolin has low cost and can improve the hand feeling of coating film. Calcined kaolin has high cost, but high whiteness and small particle size. It is widely used in exterior wall coating. Ultrafine calcined kaolin can be used to replace about 15% - 20% titanium dioxide in powder coating and high-grade exterior wall coating.
5. Calcium sulfate
There are two basic forms: anhydrous gypsum and gypsum (gypsum powder). Anhydrous gypsum is widely used in coating, which can be calcined by gypsum. Anhydrous gypsum has bright color and good dispersibility, which can be used in some bright coatings and other coatings with special requirements.
Shanghai Innovy Chemical New Materials Co., Ltd is ISO9001-2015 certified. We mainly produce and sell chemical raw materials and products such as transparent powder, talcum powder, composite powder, glass powder, calcium carbonate powder, new material for surface treatment powder, and environmentally-friendly coatings, etc. After more than 10 years of development, our company has become a large-scale private chemical raw material supply enterprise integrating production, transportation and sales system.
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