As we all know, calcium carbonate is an important inorganic compound with wide sources, abundant reserves, low industrialization cost and wide application. It is composed of three different elements, C, O and Ca, and its molecular formula is CaCO3. According to different industrial preparation methods, calcium carbonate is divided into three types: heavy, light and active calcium carbonate. Among them, light calcium carbonate is formed by chemical methods, and its density is smaller than that of heavy calcium, but in terms of sedimentation volume, light calcium carbonate has a larger value, so it is also called precipitated calcium carbonate, usually expressed as PCC.
The particle size of light calcium carbonate prepared by chemical method varies from nanometer to micrometer, and the particle shape includes hollow sphere, square shape, flower shape, chain shape and multi-level structure. As a basic raw material in chemical industry production, light calcium carbonate is widely used.
1. Paper making
The paper industry is one of the largest markets for calcium carbonate. The heavy calcium carbonate filler is mainly used for printing paper, advertising paper, office paper, writing paper, etc., except for cigarette paper, filter paper and special low-quantity information paper. Compared with heavy calcium carbonate, light calcium carbonate has better quality, has the advantages of fine particle size, high whiteness, low price, low foaming property and good printing adaptability. and optical performance requirements.
Correlation analysis shows that spindle-shaped calcium carbonate with ultra-fine particle size can improve the quality and wear resistance of high-grade paper without modification, and filling spindle-shaped calcium carbonate in pulp can simulate fine fibers, and there will be a large number of small air cells , thus obtaining excellent smoothness and printability.
2. Rubber
Light calcium carbonate is widely used in rubber products, such as tires, conveyor belt hoses, tapes and medical rubber products, which can reduce the amount of rubber used, reduce costs and also play a role in reinforcement and semi-reinforcement. Light calcium carbonate filled rubber can obtain higher tensile strength, abrasion resistance and tear strength than pure rubber vulcanizate, and has a significant reinforcing effect in natural rubber and synthetic rubber, and can adjust the consistency at the same time.
Relatively speaking, the toughness-enhancing performance of acicular calcium carbonate is stronger than that of ordinary fillers. After filling in the material, it can improve the strength, hardness and wear resistance of the material.
3. Plastic
Light calcium carbonate can act as a skeleton in plastic products, which has a great effect on the dimensional stability of plastic products, can improve the hardness of products, and can also improve the surface gloss and surface smoothness of products. Adding calcium carbonate to general plastic products can improve the heat resistance. Since the whiteness of light calcium carbonate is above 90%, it can also replace expensive white pigments and play a certain role in whitening.
4. Paint
Calcium carbonate is an important filler in paint production, and the fineness and particle distribution determine the transparency of the paint. Light calcium carbonate is used in a large amount in the paint industry and is an indispensable skeleton. The amount used in thick paint is more than 30%, the amount of phenolic enamel is 4-7%, and the amount of phenolic fine pattern wrinkle paint is more than 39%.
5. Coating
Compared with heavy calcium, because light calcium is artificially synthesized, the crystal form and composition are easy to control, so it can endow light calcium with multiple functions, and the relatively high specific surface area makes the reinforcement effect of the powder in the coating significantly better. in heavy calcium. Ordinary light calcium is mainly used in anti-corrosion coatings (including ship coatings, container coatings, vehicle primers, bridges and steel structure anticorrosion, etc.) except for architectural coatings, paper coatings, and powder coatings. In addition to fillers, it also has certain water resistance and corrosion inhibition.
6. Ink
The application of light calcium carbonate in ink can make the gloss of the paint film clear and long-lasting; it can make the printing tone of the ink elegant and uniform, and its good translucency, gloss and fluidity can also reduce the cost of paint and ink. Spherical and cubic nano-calcium carbonate is better than other fillers in dispersibility, transparency, gloss and hiding power, and is widely used in high-quality inks in the fields of rapid printing and laser typesetting.
7. Medicine
Light calcium carbonate is used in pharmaceutical formulations as a neutralizer, filter aid, buffer and solubilizer as well as filler and calcium source supplement. Moreover, the calcium carbonate with a hollow structure has better biocompatibility and can be used as a drug delivery and diagnostic marker.
8. Food
Light calcium carbonate is widely used in calcium supplementation and nutritious food industry in modern life. It is a high-quality nutritional fortification additive in industries such as dairy products, meat products and flour products, dairy milk powder, and milk tablets. In the process of preparing penicillin, streptomycin and oxytetracycline, a large amount of calcium carbonate is required. As an additive in food to ensure the necessary calcium intake of the human body, such as chewing gum, chocolate, yogurt, calcium tablets, jelly and other beverages as a fortifier to meet the human body’s demand for calcium. Light calcium carbonate is used as an alkaline agent, nutritional supplement, dough conditioner, curing agent, yeast nutrient, anti-caking agent, bulking agent, gum aid and modifier in food processing. Food grade CaCO3 content is high, impurities are low, Pb, As, Hg, Fe and other indicators are particularly low.
9. Feed
Light calcium carbonate is used in feed as a calcium supplement in feed processing. Feed grade light calcium carbonate must meet the following standards: calcium carbonate (CaCO3) content ≥ 98%; calcium carbonate (Ca) content ≥ 39.2%; moisture content ≤ 1%; hydrochloric acid content ≤ 0.2%; heavy metal content (Pb) ≤ 0.003%; arsenic (As) ≤ 0.0002%; barium salt (Ba) ≤ 0.030%.
10. Toothpaste
Light calcium carbonate can be used in daily chemical products such as tooth powder, toothpaste, cosmetics, etc. Light calcium carbonate is used as a friction agent in toothpaste, which can not only remove dental plaque and material residues, polish teeth without damaging tooth enamel, but also has good aroma permeability and paste diffusion; in addition, it is slightly alkaline , can neutralize the acidic metabolites of dental plaque bacteria such as citric acid and reduce the pH value of the oral cavity. It has multiple functions such as removing acidic plaques and neutralizing acidic metabolites in the oral cavity.
11. Sealants and adhesives
Calcium carbonate is used as a semi-reinforcing filler in adhesives, which can change the properties of the adhesive layer, reduce the cost of the adhesive, and basically does not react with the base material. Adding a certain amount of calcium carbonate to the adhesive can increase its bonding strength, hardness, heat resistance, dimensional stability, and reduce curing shrinkage and linear expansion coefficient. Such as the commonly used glass glue, without the use of reinforcing fillers, the bonding force becomes very poor. Adding industrial calcium carbonate can improve the strength of the bonded joint, increase the surface hardness, increase the viscosity and thermal conductivity, and increase the impact toughness and wear resistance. , improve the medium resistance of the adhesive and reduce the cost. Light calcium, especially nano-scale light calcium, has good particle size stability and uniform dispersion, and can provide sealants with good elasticity, water resistance, air tightness, and rheology, and is an ideal sealing material.
12. Ceramics
Develop cubic calcium carbonate with uniform particle distribution, which can be used for densified ceramics manufactured at a low temperature of 600 °C.
13. Cable
In cable products, light calcium carbonate can improve electrical insulation performance, moderate pH, good compatibility with resin, increase filling amount and reduce cost, especially suitable for filling PVC wire and cable materials.
Functionalization and specialization will become the development trend of light calcium carbonate, and the product structure will also undergo great changes. High-end products such as nano-scale calcium carbonate, ultra-fine calcium carbonate, medical grade and food grade calcium carbonate; various surface-modified special calcium carbonate, such as natural rubber special, synthetic rubber special, coating special light calcium carbonate, will surely be sold in large quantities Put it on the market to meet the market demand.