First, a conceptually accurate definition of heavy calcium and light calcium should be given separately.

Some people use the sedimentation volume (with absolute ethanol as the sedimentation medium) to distinguish between heavy calcium and light calcium, that is, light calcium with a sedimentation volume of 2.5 mL/g or more, and heavy calcium carbonate of 1.2-1.9 mL/g .

We distinguish between different production processes. Heavy calcium is made by mechanically pulverizing and sorting ore. Light calcium is formed by calcination, digestion and recarbonation of ore.

Some people start from the phenomenon that the same weight of calcium carbonate is naturally different when they are piled up naturally. It is mistaken that light calcium is light. In fact, the apparent density of the two is different, and the true density is very small. The true density of heavy calcium is 2.6-2.9 g/cm ³ and light calcium is 2.4-2.6 g/cm ³ .

Some people think that the heavy calcium used in the fillers used in foreign plastic products is dominant. The classic saying is 14-18:1. Therefore, the plastics industry should try to use heavy calcium instead of light calcium.

Some people have done a comparative test of adding heavy calcium and light calcium to rubber. The conclusion is that the same amount and the same processing conditions are more likely to be mixed with heavy calcium, which is easier to disperse in the rubber matrix, and the addition of heavy calcium is more than the addition of light calcium. The tensile strength is high, but the heavy calcium-filled rubber has a large shrinkage and a rough surface. The heavy calcium used is -400 mesh, and its price is only half that of the control light calcium, and its economic benefits are considerable.

The use of heavy calcium and light calcium and rubber products in plastic products is similar. Some manufacturers report that using -400 mesh heavy calcium instead of light calcium under the same conditions has obvious advantages for products sold by weight, but if the product is sold by length, area or number, the heavy calcium is not lighter than Calcium has an advantage.

For example, pipes, materials of the same weight, when the filling amount is the same, the length of the obtained product is different, and the filling of heavy calcium is a few thousandth shorter than that of the pipe filled with light calcium, and the accumulation is quite large. The difference in area of ​​artificial leather or synthetic leather measured by area is also sensible, so plastics processing plants do not easily give up the use of light calcium.

From an academic point of view, there are many differences between heavy calcium and light calcium, different crystal forms, different specific surface areas, different oil absorption values, etc., and the particle size and distribution of -400 mesh heavy calcium and light calcium are far apart. In what form of particles of heavy or light calcium in a plastic matrix, are individually distributed in the matrix macromolecules, or in a cluster, distributed as loose aggregates in the matrix resin, and these particles and resin macromolecules how the interface state, the force is directly related to material properties.

The use of heavy calcium in plastic products, or light calcium, can not be generalized, should be based on the full use of their respective advantages, combined with technical and economic factors to consider and then decide.

For example, in the production of polyvinyl chloride artificial leather, it can be divided into a doctor blade method, a calendering method, an extrusion method, and the like according to a manufacturing process, and a polyvinyl chloride paste resin is used in the blade coating method, and a large amount of a plasticizer is required. The absorption of light calcium is 4-5 times higher than that of heavy calcium . Therefore, using light calcium requires more plasticizer than using heavy calcium to achieve the same flexibility. If the amount of plasticizer can be reduced, use heavy calcium. It may be more economical.

Another example is a unidirectionally stretched product such as a polypropylene woven bag, a woven cloth, a packing tape, etc. The use of heavy calcium and light calcium as a filler has not found any difference in length. It has been found that the filler particles are mostly located in a large stretched shape. After several times of stretching between the molecules and rapid cooling, the morphology of the macromolecules is rapidly frozen, and the true density of light calcium and heavy calcium is almost the same, so the effect on the final length of the product is not obvious. On the other hand, heavy calcium has better processing fluidity and lower price than light calcium, so heavy calcium accounts for absolute dominance in this uniaxially stretched product .

In addition, China's plastic door and window profile processing technology is imported from abroad, the introduction of the production line and the introduction of the product formula, the filler is light calcium, the amount is 8-10Phr . It should be noted that the formula provided abroad is scientific, and the starting point for the addition of calcium carbonate is to improve the overall performance of the profile rather than to reduce costs with cheaper materials. Nowadays, using heavy calcium instead of light calcium is bound to face several problems:

The production of plastic profiles is gradually developing towards large-scale and high-volume production. The replacement and replacement of a raw material is related to the quality and stability of a large number of products. Therefore, plastic products processing plants will not easily replace a certain component in the formulation.

Calcium carbonate has become an indispensable important raw material for the plastics industry. The rapid development of the calcium carbonate industry provides the plastics industry with the material conditions of choice and exploration. Its good application in plastic materials has also led to the development of the calcium carbonate industry.

Here, we hope that the powerful enterprises in the calcium carbonate industry should not only make calcium carbonate products better, but also further develop new plastic materials and new products with calcium carbonate as the main raw material instead of simply producing a certain product. It must be used in the plastics industry.

In addition, it should be said that there are many experts and technical talents in the plastics industry, but for many plastics companies, there are still many companies that do not use the knowledge of fillers and filling modification. If our calcium carbonate industry personnel know their own How to use the products in plastic processing products, develop deep processing products with calcium carbonate as the main raw material, and sell calcium carbonate at the same time as the application technology of calcium carbonate, then China's calcium carbonate products will have broader application prospects.