Yuan lei small class | how to improve the gloss of precipitated barium sulfate application products?
The gloss of the coating refers to the reflective ability of the coating surface to the light of the projected light. The stronger the reflective ability, the greater the gloss. The main factors affecting the gloss of barium sulfate powder material after film formation are its particle size and dispersion performance. If the particle size of barium sulfate powder itself is very fine and can be evenly dispersed into the coating, the coating film will be smooth and dense like a mirror, and the gloss will be very obvious. On the contrary, the particle size of barium sulfate is too coarse and the uniformity is poor, the coating surface is rough, the gloss will decrease and the color tone will be dark.
Gloss is an important performance index of ink, which has a great influence on the appearance quality of printed parts. The traditional precipitated barium sulfate (Glauber's salt method), not only poor dispersion, and low gloss, can not be applied to the ink formulation system. Better barium sulfate material is actually added to the ink formulation in the form of concentrated slurry. In ink production, different types of ink products have different quality requirements for barium sulfate materials. In addition, in the process of ink formulation, barium sulfate with different properties should be selected according to the specific characteristics and requirements of various types of ink.
1. Evaluation method of gloss
One method is to make dry-based barium sulfate and standard samples into coating film contrast gloss analysis: barium sulfate samples are evenly dispersed in alkyd resin by sanding, and under the controlled conditions of automatic spraying equipment, a wet film coating with uniform film thickness and surface characteristics is formed on the aluminum plate, and then baked. Another system is mixed with resin to prepare 40% barium sulfate volume concentration water-based acrylic coating, with a 100 micron wire bar automatic coating film, put in a dust-free cabinet after drying for at least 5 hours with a gloss meter to measure 20 gloss.
The barium sulfate powder material is mixed with refined linseed oil on a flat grinder to make a paste, and then the film is coated on a glass plate with an automatic wet film preparation for measurement. Evaluating the gloss of a paint is not entirely objective, but there is usually a reasonable correlation between the visual ratings made by different observers.
2. Technology to improve the gloss of barium sulfate
High gloss, high weather surface treatment barium sulfate preparation method, the product surface coated with porous alumina and dense alumina. Dense alumina is an alumina containing sulfate ions, wherein the sulfate ions are present in the form of being adsorbed in alumina, and the mass ratio of alumina to sulfate ions is 10:1 to 1.3:1. The alumina is contacted and reacted with sulfate ions for a period of time at a temperature of (30-65) °C and a pH of (5.2-6.5), so that the alumina is densified. Boehmite is a crystalline form of alumina that contains adsorbed water. Water is inserted into Al(OH) in both random and regular ways.6Octahedral layer. BaSO4The surface of the crystal is coated with dense alumina to improve its durability such as light resistance and pulverization resistance. In BaSO4Coating the crystal surface with a thin layer of diasperite alumina improves its gloss and dispersibility.
Another preparation method of surface treated barium sulfate with improved gloss and weatherability: Barium sulfate is treated with various metal salts, such as zirconium and phosphorus compounds, at least one metal salt can provide a monovalent anion. It has been found that polyvalent anions such as SO4 in soluble metal salts2-In the coating process of ion exchange will be attached to the surface of barium sulfate crystals, conventional water washing to remove these polyvalent anions caused by flocculation, reduce the dispersion and the final product whiteness, gloss and weather resistance. A metal salt containing a monovalent anion will effectively reduce this tendency and possibility.
By strictly controlling the pH, temperature, silicon and aluminum addition time of barium sulfate slurry, the surface treatment barium sulfate powder material with improved gloss and weather resistance was prepared. The entire continuous process includes a residence time of no more than 120 minutes. The surface treatment of barium sulfate has excellent gloss advantage, at the same time in the paint, ink and coating has a good compatibility. The tinting strength and Heigman data show that the barium sulfate prepared by this method is well dispersed and does not agglomerate when used in paints and inks.
2.1 Technology for Improving Gloss and Dispersion of Barium Sulfate
After the treated barium sulfate surface is deposited with at least one monobasic amine salt treatment, the final prepared barium sulfate material is significantly improved in application gloss and dispersibility. Compared with untreated barium sulfate and barium sulfate treated with TME or other amine salts, the surface-treated barium sulfate prepared by this method is significantly improved in dispersibility and gloss, especially when it is used in water-based coatings, the amount of dispersant can be significantly reduced, which is also its greatest advantage.
3. Other technical status of improving the gloss of barium sulfate application
Barium sulfate powder was coated with aluminum oxide to improve the gloss and dispersion of its oily system. The basic aluminum compound and the acidic aluminum compound aqueous solution are added in sequence, and the total amount is 1wt% to 4wt% of the volume weight of barium sulfate in the suspension, wherein the ratio of the amount of aluminum element added in the basic aluminum compound aqueous solution to the amount of aluminum element added in the acidic aluminum compound aqueous solution is 1:1 to 1:3. The process can be used to treat barium sulfate slurries prepared in any form, and the steps can be carried out batchwise or continuously.
Barium sulfate, gloss, treatment, alumina, surface, ink, dispersion, method, preparation
Kaolin is a non-metallic mineral, which is a kind of clay and clay rock mainly composed of kaolinite clay minerals. Because it is white and delicate, also known as white earth. It is named after Gaoling Village, Jingdezhen, Jiangxi Province.
Barium sulfate is based on barite as the main raw material, through beneficiation, ore washing, crushing and other processes. Barium sulfate has a hardness of 3~3.5 (Mohs) and a specific gravity of 4.3~4.7. It has the characteristics of high specific gravity, low hardness and brittleness. Barite is almost insoluble in water, ethanol and acid, soluble in hot concentrated sulfuric acid. With the development of some high-performance barium sulfate products, the application field of barium sulfate is constantly expanding.
The main component of talc is hydrated magnesium silicate, which is monoclinic. The crystals are false hexagonal or rhombohedral flakes. Ores are usually dense massive, leaf-like, radial, fibrous aggregates. Colorless transparent or white, but with a small amount of impurities and light green, light yellow, light brown, light red and even black; cleavage surface was pearl luster. Soft, Mohs hardness 1-1.5, specific gravity 2.7-2.8.