Yuan Lei's Little Knowledge | Application of Heavy Calcium, Light Calcium and Nano Calcium in Coatings
Calcium carbonate is the most widely used pigment in coatings, which plays the role of filling the skeleton and substrate in the paint film, and improves the performance of the coating. So what are the applications of heavy calcium carbonate, light calcium carbonate and nano calcium carbonate in coatings? Let's take a look at the following.
heavy calcium carbonate
Heavy calcium carbonate is the first filler in the world's coating industry. China's coating industry consumes more than 400000 tons of heavy calcium every year. Among them, architectural coatings, paper coatings and powder coatings are the most consumed areas of heavy calcium.
(1) As an extender pigment, it has a filling effect to make it delicate, uniform and high whiteness.
(2) has a certain dry hiding power, the general use of ultra-fine products, when its particle size and titanium dioxide particle size close, can improve the covering effect of titanium dioxide.
(3) can improve the film strength, water resistance, dry, scrub resistance.
(4) Improve color retention.
(5) Reduce costs, the use of 10% to 50%.
Light calcium carbonate
Compared with heavy calcium, light calcium is artificially synthesized, and the crystal form and composition are easy to control, so light calcium can be endowed with multiple functions, and the relatively high specific surface area makes the reinforcing effect of powder in the coating obviously better than heavy calcium.
(1) As an extender pigment, it has a filling effect, is delicate and increases whiteness.
(2) has a certain dry covering power.
(3) the density is small, the specific surface area is large, with a certain suspension, play a role in anti-settling.
(4) Reduce costs.
(5) increase the feel. Disadvantages: easy frosting, swelling, thickening, the amount should not be too large, can not be used in exterior wall coatings.
nano calcium carbonate
With the rise of nanotechnology, nano calcium carbonate as a cheap nano particles, in the coating industry has become a hot topic, compared with heavy calcium and light calcium, although the cost increases, and has a better reinforcing effect, but nano calcium carbonate in the coating can also improve the coating hiding power, gloss, transparency, quick drying, and stability. In some industries, such as automotive coatings, architectural coatings, etc., nano calcium carbonate can partially or completely replace the high price of titanium dioxide, in order to reduce the cost of enterprises.
(1) Building materials: nano calcium carbonate due to the existence of "blue shift" phenomenon, in the latex paint can shield ultraviolet light, play a heat insulation effect, the anti-aging properties of the coating has been improved. Applied to exterior wall coatings, the coatings exhibit strong "hydrophobicity". The cracking strength and contamination resistance of the coating are enhanced.
(2) Coating and topcoat: because the nano calcium carbonate particles dispersed in the coating are extremely small, under a certain volume fraction, the number of particles increases sharply, the average distance between particles decreases, and the chance of any two particles entering the mutual attraction zone increases rapidly, resulting in an increase in viscosity. When the material is under stress, the sliding between a large number of particles attracts more impact energy, this is reflected in a wide temperature range with a higher damping value, and the treatment agent layer on the surface of nano calcium carbonate can effectively transfer and relax the stress on the interface between organic and inorganic materials, and better absorb and disperse impact energy. Considering the flexibility of the treatment agent itself, the mechanical strength of the coating film is improved.
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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.