How To Choose Light Calcium Or Ground Calcium

1.1 the difference in the application effect of light calcium and ground calcium

Some people believe that the ground calcium in the fillers used in foreign plastic products occupy a major position, the classic saying is 14-18:1, so the plastic industry should try to use ground calcium instead of light calcium.

Someone has done a comparative test of adding ground calcium and light calcium to rubber. The conclusion is that adding ground calcium is easier to mix and process under the same amount and processing conditions, and it is easier to disperse in the rubber matrix, and adding ground calcium is better than adding light calcium. The tensile strength is high, but the rubber filled with ground calcium has large shrinkage and rough surface. The ground calcium used is -400 mesh, and its price is only half of the light calcium used in the control, and its economic benefits are very considerable.

The use of ground calcium and light calcium in plastic products is similar to rubber products. Some manufacturers report that using -400 mesh ground calcium instead of light calcium under the same conditions has obvious advantages for products sold by weight, but if the products are sold by length, area or number, ground calcium is no better than light calcium. Calcium has advantages.

For example, for pipes with the same weight of materials, when the filling amount is the same, the length of the product obtained is different. The filling of ground calcium is a few thouhs shorter than the pipe filled with light calcium, and the accumulation is quite large. For artificial leather or synthetic leather measured by area, the difference in area can also be felt. Therefore, plastic products processing plants do not easily give up the use of light calcium.

1.2 Use ground calcium or light calcium? Cannot generalize

From an academic point of view, there are many differences between ground calcium and light calcium, such as different crystal shapes, different specific surface areas, and different oil absorption values, and the particle size and distribution of -400 mesh ground calcium and light calcium are quite different. In the plastic matrix, in what form does the ground calcium or light calcium particles exist, are they individually distributed in the matrix macromolecules, or are they distributed in the matrix resin in the form of loose aggregates, and these particles The state of the interface with the resin macromolecule is directly related to the mechanical properties of the material.

Whether ground calcium or light calcium is used in plastic products cannot be generalized. On the basis of giving full play to their respective advantages, a comprehensive consideration should be made in combination with both technical and economic factors.

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

Another example is polypropylene woven bags, woven fabrics, packing tapes and other unidirectional stretch products. The use of ground calcium and light calcium as fillers has not found any difference in length. After research, it has been found that most of the filler particles are located in the large After several times of stretching and rapid cooling in the gaps between molecules, the shape of the macromolecules is rapidly frozen, while the real density of light calcium and ground calcium is almost the same, so the effect on the final length of the product is not obvious. On the other hand, ground calcium has better processing fluidity than light calcium, and the price is much lower. Therefore, ground calcium occupies an absolute dominant position in this unidirectional stretched product.

In addition, the forming and processing technology of profiled materials for plastic doors and windows in my country is imported from abroad, and the product formula is also introduced when the production line is introduced. The filler is light calcium and the dosage is 8-10Phr. It should be pointed out that the formula provided abroad is scientific. The starting point of adding calcium carbonate is to improve the overall performance of the profiled material rather than to reduce the cost by using cheap raw materials.

Now replacing light calcium with ground calcium is bound to face several problems:

• ①In what size range of ground calcium should be used to replace the light calcium being used?
• ②Can the material properties of the profiled material not change significantly after the equivalent replacement? Does the appearance of the product affect?
• ③Should the processing equipment, head mold and process conditions be adjusted accordingly after the equivalent replacement?
• ④After the equivalent replacement, due to the good processing performance of ground calcium, can it reduce the material flow resistance (reflected in the screw torque change), thereby saving energy consumption or increasing the speed and increasing the production rate?
• ⑤ Is it cost-effective to compare gains and losses?

The production of plastic profile materials is gradually moving towards large-scale and mass production. The substitution and replacement of a raw material is related to the quality and stability of a large number of products. Therefore, plastic product processing plants will not easily replace a component in the formula.

1.3 How can calcium carbonate be better used in the plastics industry?

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

Here, we hope that powerful companies in the calcium carbonate industry will not only do a good job of calcium carbonate products, but also further develop new plastic materials and new products using calcium carbonate as the main raw material, instead of simply producing a product. Must be used by the plastics industry.

In addition, it should be said that there is no shortage of experts and technical personnel in filling modification in the plastics industry. However, for many plastic companies, there are still many companies that do not use fillers and filling modification knowledge specifically. If our calcium carbonate industry personnel know their own How to use the product in plastic processing products? If we develop our own deep-processed products with calcium carbonate as the main raw material, and sell calcium carbonate while exporting the application technology of calcium carbonate, then my country's calcium carbonate products will have a broader application prospect.

1.4 How is calcium carbonate used in the thermoplastic elastomer industry?

Calcium carbonate is commonly used in the thermoplastic elastomer industry, especially in the TPE-S and TPV industries. Generally, TPE-S uses more ground calcium, while TPV industry uses more light calcium. Generally speaking, for injection specifications of thermoplastic elastomers, the requirements for calcium carbonate are lower than those of extrusion specifications. From the perspective of cost and dispersion effect, ground calcium is generally preferred, and light calcium is preferred if performance is more important.