Plastic is an important production and daily necessities in today’s society. The use of inorganic powder can effectively improve the physical and chemical properties of plastic products and improve the efficiency of plastic products.
1. Application varieties of inorganic powders in plastics
Wollastonite
Wollastonite is a natural calcium silicate (CaSiO3) with a light white needle-like structure. The length-diameter ratio (L/D) of wollastonite after processing can reach more than 15/1. It is a fibrous inorganic reinforcing filler in plastics. , has excellent tensile strength and flexural strength, and has particularly good moisture resistance, can be widely used in automobiles, home appliances, tools and other plastic products that are easily deformed by heat.
Talc
Talc has a sheet-like structure, and it has obvious reinforcing and modification effects in plastics and rubbers, and can improve the tensile strength, impact performance, creep resistance, heat resistance, tear resistance, etc. of plastic products. Improve the surface appearance of products, reduce product shrinkage, improve barrier effect, reduce air permeability, and increase rigidity and flexural modulus of plastic products.
Barium sulfate
The natural ore (barite) is pulverized, washed with water and dried to obtain barite powder (also called barium sulfate). Barium sulfate has excellent properties such as chemical stability, scratch resistance, heat resistance, high refractive index, sound insulation, heat preservation, and high gloss.
Mica
Mica is a layered aluminosilicate hydrochloride mineral with a unique structure. In addition to its reinforcing effect, it can also improve the air tightness, optical properties, and insulating properties of plastics.
Glass beads
Glass microbeads have the advantages of high temperature resistance and low thermal conductivity. Filling plastics can not only increase the wear resistance, compression resistance and flame retardancy of the material, but also its special spherical surface can improve the processing fluidity of the material; in addition, It has good surface gloss, which can increase the surface gloss of the product and reduce the dirt adsorption on the surface.
Magnesium hydroxide
The chemical formula of magnesium hydroxide is Mg(OH)2, which can be prepared by chemical methods or obtained from brucite ore by crushing. Magnesium hydroxide has a flame retardant effect, and it can be filled into plastics through surface modification to achieve the effect of smoke suppression.
Aluminum hydroxide
Aluminum hydroxide is a compound with the chemical formula Al(OH)x, which is flame retardant, smoke suppressing, and filling in PVC. Most of the time it is used in thermosets because it reduces its mechanical strength when used in thermoplastics.
2. Application of calcium carbonate in plastics
In terms of reduction, resource utilization, environmental protection and cost reduction, calcium carbonate belongs to many inorganic powders. Calcium carbonate is used in the largest amount in filling and modified plastics, and it also involves the most plastic products.
Calcium carbonate is widely used in filled polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), acrylonitrile butadiene-styrene copolymer (ABS) and other resins. Calcium carbonate can play a skeleton role in plastic products, which has a great effect on the dimensional stability of plastic products, and can also improve the hardness of products, and improve the surface gloss and surface smoothness of products. Since the whiteness of calcium carbonate is above 92, it can also replace expensive white pigments.
Calcium carbonate is divided into heavy calcium carbonate and light calcium carbonate, both of which are widely used in plastics, rubber, papermaking, paint and coatings and other industries, but because of the differences in particle size and surface effect, there are differences in the use effect. , both have advantages and disadvantages to each other.
For example, the oil absorption value of heavy calcium is generally about 10-15 degrees lower than that of light calcium. The same proportion can replace the light calcium in the plastic formula, which can reduce the use of activating additives; because the heavy calcium particles are relatively loose, the particle shape is also irregular. , After combining with plastic polymer, the stress is small, and the product is brittle. For plastic products filled with the same proportion of calcium carbonate, the plastic products filled with light calcium have better flexibility than those filled with calcium carbonate.
In plastic products, the advantage of light calcium is reinforcement, which can improve the impact strength of products. The use of heavy calcium in plastics can reduce costs, has good affinity with resins, high dispersion, similar refractive index to plastics, easy to color, and can improve the strength and stability of plastic products. Nano calcium carbonate is mainly used in high-grade plastic products, which significantly improves the rigidity and toughness of modified plastics.
Inorganic powder is a functional material with abundant resources, low price and excellent performance. In addition to purity, a very important technical indicator of inorganic powder for filling and modified plastics is particle size and particle size distribution. In addition, the application path of the final product is also an important basis for selection. With the requirements of functionalization, greening, and refinement, inorganic powders for plastic modification are also developing in the direction of innovation, standardization, greening, nanometerization, compounding, organicization, and lightweighting. The demand for high-end calcium carbonate products has also increased, and the development prospects are broad.