Mica Application in Resin and Plastic Industries

(1) Changing the Optical Properties of Plastics

Mica chips can reflect and radiate infrared rays as well as absorb and shield UV, etc. Therefore, if adding high-quality wet ground mica into agricultural films, it will be difficult for light to go out after penetrating in, thus preserving heat to greenhouse and field plastic film, etc. In this application, the purity and flaky structure of mica powder are very important. On one hand, impurities will reduce mica of its enhancement effect, influence its transparency, increase the fog level as well as decrease light’s entering of the greenhouse. On the other hand, if the mica is not good in flaky structure, then its effect of obstructing infrared radiation is also poor. Gansu Gelan Chemical Technology Co., Ltd., of Hong Kong Lee Group ever used wet ground mica to make agricultural film, only to reduce its transparency by 2%.

Drugs, cosmetics, food and other products need to shield out radiation, particularly ultraviolet radiation, to improve their storage performance. To make this, we can add perfectly flake-structured wet ground mica powder into their plastic packing materials. Large-size mica filler can improve the luster of materials (pearlescent effect), and fine mica powder can remove the luster. 

img (1)

(2) Improving Air-Tightness of Plastics

Wet ground mica powder has excellent thin sheet shape, with the thickness in nanometers and diameter-thickness ratio up to 80 ~ 120 times, thus having a very large effective blocking area. The air-tightness of plastics will be dramatically increased after adding in high-quality and high-purity wet mica powder. Such plastics, according to the patent literature, can be used to make Coke bottles, beer bottles, medicine bottles, moisture-proof packaging materials as well as many similar special kinds of plastic packaging materials.

(3) Improving Physical and Mechanical Properties of Plastics

Flaky and fibrous fillers can decentralize the stress of materials, which is similar to the reinforcing steels in the cement concrete and the anisotropic materials in many enhancing materials (plastic, rubber, resin, etc.). Its most typical application is in carbon fiber, but carbon fiber is quite expensive and limited in luster, therefore, it is difficult to put it into application.

Asbestos is strictly limited in application for it can cause cancer. Ultra-fine glass fiber (e.g., diameter of 1 micron or in nanometer level) faces many difficulties in manufacture and its price is also rather high. Granular filler, including micron quartz powder and kaolin powder that abound in dry ground mica do not possess this function like sand and stones in the cement concrete.Only when adding filler as wet ground mica powderthat is high in diameter-thickness ratio, the tensile strength, impact strength, elastic modulus, other mechanical properties, shape stability (such as heat denaturation and anti-torsion fatigue creep variability), and anti-wear performance will be improved significantly.Quite a lot of study about this has been carried out in Materials Science. One key is the sizes of fillers.

Plastics (e.g., resin) are limited in terms of hardness themselves. Many types of filler (e.g., talc powder) are quite low in their mechanical strength. On the contrary, being one of the components of granite, mica is excellent in hardness and mechanical strength. Therefore, by adding mica powder as filler in plastics, the enhancement effect will be quite enormous. High ratio of diameter-thickness is the key for the enhancement effect of high-purity mica powder.

img (2)

The coupling treatment of mica powder has a great role in the above application for it can dramatically improve the chemical integrity of materials, thus greatly enhancing the performance of materials. The correct coupling treatment is also a key for the enhancement property of mica powder, so does changing the crystallization process of resin. Using high-quality mica powder can make the products more frivolous. This kind of technology is widely applied in plastics industry, such as in the manufacturing of high-strength products, including plastic parts of machinery and vehicles, earthwork materials, outer skin of household appliances, packing materials, daily use, etc.

(4) Improving the Insulating Property of Plastic Products

Mica has a very high rate of electric resistance, so it’s a high-performance insulating materials itself. Using mica to improve the insulation property of materials is a well-known technology. For manufacture of high insulation plastic products, functional filler wet ground mica can be added in. As stated above, mica high in iron content shall be avoided for its low insulation function. Dry ground mica hasn’t been washed of mine and is high in iron content, so it is not suitable for using.

The application of wet ground mica in plastics is far more than that. Making full use of the unique properties of wet ground mica powder, many new valuable plastic products and application technologies can be developed out. For example, by adding mica powder into plastics, printing performance and composite bonding properties can be improved; by subsiding SnO2 on the surface or by being plated with metal, mica powder will be conductive and can be used to make anti-static products and conductive plastics; by being coated with TiO2, mica will be pearlescent pigment and can be used in many applications; by being colored, mica will be excellent pigments; mica can also improve the lubrication performance of products.

Post time: Jun-23-2020