Calcium carbonate can not only reduce the raw material cost of plastic products, but also improve some properties of plastic materials. In recent years, gratifying achievements have been made. The research results of many universities and scientific research institutions show that if used properly, different types of calcium carbonate can significantly improve the performance of matrix plastics. However, the difference between light calcium carbonate and heavy calcium carbonate has always bothered most users.
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The differences are as follows:
1. Different sources
Light calcium carbonate is chemically synthesized calcium carbonate, also known as precipitated calcium carbonate, colloidal calcium carbonate or activated calcium carbonate. It can even produce nano-sized calcium carbonate, called light calcium. The limestone raw material is calcined to produce lime and carbon dioxide, and then water is added to digest the lime to produce lime milk. Its main component is calcium hydroxide, calcium hydroxide is introduced into carbon dioxide to carbonize lime milk to form calcium carbonate precipitate. After dehydration, drying, crushing or double decomposition reaction of sodium carbonate and calcium chloride to form calcium carbonate precipitate, it is dehydrated, dried and crushed. Heavy calcium carbonate, referred to as heavy calcium, is directly crushed natural calcite, marble, chalk and shells by mechanical methods.
2. Different bulk density
The obvious difference between heavy calcium carbonate and light calcium is the different bulk density of the product. The bulk density of heavy calcium products is relatively large, generally 0.8-1.3g/cm3; the bulk density of light calcium products is relatively small, mostly 0.5-0.7g/cm3; and the bulk density of some nano calcium carbonate products is lower, reaching about 0.28g/cm3. Heavy calcium and light calcium products can also be roughly distinguished by the packaging volume of the product. Generally speaking, the packaging capacity of heavy calcium products is 25 kg/bag, while the packaging capacity of light calcium products of the same quality is significantly larger. Some nano calcium carbonate products also use 15kg/package or 20kg/package.
3 different whiteness
Due to the large impurity content in heavy calcium carbonate products, the whiteness of the products is generally 89%-93%, and only a few products can reach 95%. The light calcium product adopts chemical synthesis, which removes a large amount of impurities and has high purity. Therefore, the whiteness is mostly 92%-95%, and some products can reach 96%-97%, which is also the main reason why light calcium products are mostly used to fill high-grade or light-colored products.
4 Different water content
The water content of ground calcium carbonate products is generally 0.2-0.3%, which is relatively low and stable. The water content of some high-grade heavy calcium products can even reach about 0.1 percent. The water content of ordinary light calcium products is 0.3-0.8%, sometimes fluctuating and unstable. Traditionally, the difference between heavy calcium and light calcium is to test water with a water instrument. When the water content is close to 1% for light calcium, when the water content is less than 0.1 for heavy calcium.
5. Different particle size
The particle size range of the heavy calcium product is 0.5-45um, and the particle size of the product varies with the crushing equipment. The particle size of ordinary light calcium products is generally 0.5-15um. Because the particle shape is spindle-shaped, it is difficult to accurately measure, generally in a range; the particle size of nano calcium carbonate in light calcium is fine, generally 20-200nm. The particle size of ordinary light calcium carbonate is generally about mesh, which can meet the performance requirements of PVC pipes and profiles. Therefore, considering the particle size, the traditional PVC pipes and profiles use light calcium carbonate. In the past, due to the limitation of crushing equipment, the fineness is larger. Now the particle size of heavy calcium carbonate can fully meet the needs, even finer than light calcium carbonate. Therefore, PVC pipes and profiles can be selected at present.
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Raw material: natural limestone
Calcine the selected limestone and decompose it into calcium oxide (CaO), then add water (H2O) to digest the CaO into calcium hydroxide (Ca (OH)2) emulsion, after the emulsion is refined and purified, inlet carbon dioxide to form calcium carbonate (CaCO3), and the finished products come out through dehydration, drying, crushing and packaging. This kind of calcium carbonate is called light calcium carbonate or precipitates calcium carbonate, which is also called light calcium for short. The quality of light calcium carbonate is not only determined by the quality of natural calcium carbonate, but also by chemical reaction conditions such as calcination and grading fineness.
Calcium carbonate is a very important inorganic salt raw material and the most commonly used filler in the manufacturing and processing industry. It is widely used in rubber, plastic, paper, ink, paint, building materials, crops, fruit trees, food, medicine, and other industries. Calcium carbonate usually can be divided into two forms according to the production method, and the physical and chemical properties are also different. The one that is made by a chemical synthesis reaction is called light calcium carbonate, and the other that is made by the means of physical-mechanical grinding is called heavy calcium carbonate. The most obvious differences between light and heavy calcium carbonate lie in pH value, fineness, and particle shape. The shape of light calcium carbonate is mainly spindly, while that of heavy calcium carbonate is mainly irregular particles, and the differences between fineness and shape result in the difference of apparent specific gravity. In order to achieve the desired effect, users can choose the most suitable specifications in various calcium carbonate products according to the application environment or personal use.
· The particles are smaller than the heavy calcium carbonate and have better fineness.
· High whiteness and excellent color.
· Low impurities and high purity.
· The main body of the particle structure is spindle-shaped and cylindrical.
· Good dispersity of products.
· The product is of good quality, so suitable items can be selected based on apparent specific gravity and oil absorption.