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MICA添加时间:2018-12-14

Major Applications

With muscovite the most widely used, followed by phlogopite, Mica is widely applied in industrial lines, such as in building materials, fire fighting, fire extinguishing agent, electric welding rod, plastics, electric insulation, paper making, asphalt paper, rubber, pearlescent pigments and other chemical industrials. Used as functional fillers in plastics, paints, coatings, and rubber, Super-fine mica powder can improve the mechanical strength as well as enhance the toughness, adhesion, anti-aging and corrosion resistance, etc. In addition to high electric insulation, anti-acid and alkali corrosion, flexibility, toughness, sliding, heat-proof, sound-proof, and small thermal expansivity, super-fine mica powder also takes the lead in possessing properties of smooth surface, high diameter-thickness ratio, regular shape, strong adhesion, etc. In industrial lines, with its properties of insulation, heat resistance, anti-acid, anti-alkali, compression-resistance, dry picking, it is mainly used as insulation materials for electrical materials and equipments, for making windows of steam boiler and smelting furnace as well as mechanical parts. Mica scrap and mica powder can be processed into mica paper and can also substitute mica flake to make kinds of low-cost and even-thick insulation materials.Advantages of Wet Ground MicaThe diameter-thickness ratio of particles of wet ground mica powder can reach 80-120 times, with its thickness being only about 10 nm to 100 nm. Its unique sheet structure enables it to function as a physical shield while used in flake coatings to prevent the paint film from destruction by sunlight UV, to thicken corrosion proofing layer, to restrain the permeation of corrosive medium and to reduce the relict stress in the lining. Applied in paint of outer wall in architecture, it can not only improve the coatings’ mechanical properties, but also enhance the coatings in terms of anti-aging, anti-UV, anti-cracking, and anti-dusting, while preventing the coatings from fading in color, with the pigment particle’s easy access to flaky mineral’s lattice layer. As is known to all, UV in the sunlight is the essential cause for the aging and weak functions of coatings. Super-fine flaky minerals, with its optical interference effect by interacting with interlayer crystallized water and its crystal polarizing effect, can strongly absorb and reflect UV and infrared rays, thus protecting the coatings and paints of the outer wall. After research and study, it is found that by adding 5~8% super-fine mica powder, the anti-aging property of outer wall paints can be increased to 750 hours or more. This kind of product, having a high rate of cover up and UV absorption, can effectively make the proliferation, permeation and migration of corrosive substances become extremely circuitous and tortuous (shielding and labyrinth effect) by extending the film-penetration time by 3 times, and thus greatly improve the performance of anti-corrosion coatings.

Standard of Wet Ground Mica Powder

Tech Features

Indicators

 

Specs

Screen Over-Size

%

Sand

%

Loss on Ignition

%

Bulk Density

g/³

Moisture

%

Whiteness

°

25µ

(600 mesh)

45µ≦0.05

25µ≦10.0

0.8

5.0

0.32

1.0

70

38µ

(400 mesh)

75µ≦0.1

38µ≦10.0

0.5

0.28

45µ

(325 mesh)

112µ≦0.1

45µ≦10.0

75µ

(200 mesh)

150µ≦0.1

75µ≦10.0

0.6

0.30

65

90µ

(160 mesh)

180µ≦0.1

90µ≦10.0

1.0

125µ

(120 mesh)

250µ≦0.1

125µ≦10.0

0.32

 Application in Paint and Coating Industries(1) Barrier Effect: In paint film,flaky filler will form a basically parallel arrangement, thus strongly preventing the penetration of water and other corrosive substances, and if using high-quality mica powder( diameter-thickness ratio being at least 50 times, preferably 70 times), this kind of penetration time will normally be extended by 3 times. As the mica filler is much cheaper than the special resin, it has a very high technological and economic value.In short, using high-quality mica powder is an important approach to improve the quality and performance of anti-corrosion and outer wall coatings. During the coating process, before the paint film is solidified, mica chips will lie down under the surface tension and then automatically form paralleled to one another and to the surface of paint film. The orientation of this kind of parallel arrangement is right perpendicular to that of corrosive substances’ penetrating paint film, thus playing its barrier effect to the most. The problem is that the flaky mica structure must be perfect, as foreign industrial enterprises set the standard that diameter-thickness ratio should be at least 50 times, preferably more than 70 times, otherwise the results will not be desirable, because the thinner the chip is, the larger the effective barrier area with the unit volume of the filler, on the contrary, if the chip is too thick, then it can not form many barrier layers. That’s why the granule filler simply doesn’t possess this kind of function. Also, perforation and avulsion on the mica chip will seriously affect this barrier role (corrosive substances can easily leak in). The thinner the mica chip is, the larger the barrier area with the unit volume of the filler. Better effect will be achieved with moderate size (too thin is not always good).(2) Improving Physical and Mechanical Properties of the Film: Using wet ground mica powder can improve a series of physical and mechanical properties of paint film. The key is the morphological characteristics of fillers, namely, the diameter-thickness ratio of flaky filler and length-diameter ratio of fibrous filler. Granular filler acts like sands and stones in the cement concrete to enhance the steel.(3) Improve the Anti-Wear Property of the Film: The hardness of resin itself is limited, and the intensity of many types of filler is not high (e.g., talcum powder). On the contrary, mica, one of the components of granite, is great in terms of its hardness and mechanical strength. Therefore, adding mica as filler, the anti-wear performance of coatings can be significantly improved. That’s why mica powder is preferably used into car paint, road paint, mechanical anti-corrosion coatings and wall coatings.(4) Insulation: Mica, with a very high rate of electric resistance (1012-15 ohm· cm), is in itself the best insulation material and it is a publicly known technology to use it to improve the insulation property of paint film. What’s interesting is that when working with the composite material of organic silicon resin and organic silicon and boric resin, they will convert to a kind of ceramic substance with good mechanical strength and insulating property once encountering high temperature. Therefore, wire and cable made of this kind of insulating material can still maintain its original insulation property even after fire, which is quite important for the mines, tunnels, special buildings and facilities, etc.          (5) Anti-Flaming: Mica powder is a kind of very valuable fire-retardant filler and it can be used to make flame-retardant and fire resistant paint if applied with an organic halogen flame retardant.(6) Anti-UV and Infrared Rays: Mica is very excellent in shielding ultraviolet and infrared rays, etc. So adding wet ground mica powder into the outdoor paint can significantly enhance the film's anti-ultraviolet performance and slow down its aging. By its performance of shielding infrared rays, mica is used in making heat preservation and thermal insulation materials (such as paint).(7) Reducing Sedimentation: Suspension performance of wet ground mica is very excellent. The extremely thin and tiny chips can suspend permanently in a medium without hierarchical sedimentation. Therefore, when using mica powder as filler instead of that will easily subside, the stability of coating storage will increase significantly.(8) Heat Radiation and High-Temperature Coatings: Mica has a great capability of radiating infrared rays. For instance, when working with iron oxide, etc., it can create excellent thermal radiation effects. The most typical example is its application in spacecraft coatings (reducing the temperature of the sunny side by tens of degrees). Many painting outfitting of heating elements and high-temperature facilities all need to use the special paint containing mica powder, because such coatings can still be workable under very high temperatures, such as 1000 ℃ or so. At that time the steel will become red-hot, but the paint remains unharmed.(9) Gloss Effect: Mica has good pearlescent gloss, hence, when using large-size and thin-sheet mica products, materials, such as paints and coatings, can be shiny, glossy or reflective. On the contrary, super-fine mica powder can make repeated and mutual reflection within the materials, thus creating delustering effect.(10) Sound and Vibration Damping Effects: Mica can significantly change a series of physical modulus of the material as well as form or alter its viscoelasticity. Such materials can effectively absorb vibration energy as well as weaken shock and sound waves. In addition, shock waves and sound waves will form repeated reflections between mica chips, which also results in weakening the energy. Therefore, wet ground mica is also used to prepare sound and vibration damping materials.Application in Rubber Industry(1) Improve Air-Tightness of Rubber: Air-tightness is the most important property for many rubber products, such as inner tubes, ball bladders as well as many life-saving supplies, etc. To increase the air-tightness of rubber, in addition to improve processing and coating technology, it mainly depends on the nature of the rubber itself and the filler­. The better the air-tightness of the rubber is, the better the anti-permeability of the product is. Of course, this kind of rubber is quite expensive. Therefore, using functional filler-wet ground mica powder, the cost will be much lower and the effect will be good. That’s why when oil becomes the major factor impeding the development of global economy, for example since the oil crisis of 1970s, Goodyear, Sumitomo Rubber, Bridgestone, Sipo Ting and other well-known companies have been actively engaged in researching the application of mica powder.The barrier effect of wet ground mica makes harmful substances have a difficult access into the materials and also makes them difficult to spread, migrate or penetrate even after they entered. The principles is similar to that of coatings, that is, the parallel-oriented mica chips prevent air from penetrating (penetration time will be extended by three times), which is important for inner tubes of tires, bladders of balls and many life-saving equipments. It doesn’t have to be fine or white mica, but the flaky structure must be perfect. In short, adding wet ground mica into rubber, its air-tightness will increase dramatically.(2) Insulation Performance: It is widely known that mica can be used to improve the insulation performance of materials as it has a very high rate of electric resistance. Rubber can be used for wire and cable insulation materials, therefore, using wet ground mica is very important. What should be mentioned is that electric cables used in mine shafts, tunnels and on other similar occasions, need to maintain its insulation in fire. Some countries have developed a special class of insulating material composed by silicone rubber (including organic boron resin) and mica powder and so on. Such insulating materials will convert to a kind of ceramic-like material at high temperatures, retaining good insulating property and mechanical strength, thus enabling electric cables to keep its insulation. What should also be mentioned is that as iron will reduce the insulation performance of mica, dry ground mica powder shall not be used for insulation materials.(3) Sound and Vibration Damping Effects: Lots of sound and vibration damping materials use rubber to change its viscoelasticity and other physical traits to the desirable. Wet ground mica powder with high diameter-thickness ratio can change a series of physical modulus of materials. What’s more, the energy reflection between chips (such as shock waves and sound waves) will also absorb and weaken these energies. Accordingly, "damping-chip" in vehicles and household appliances often add mica powder. Similarly, many other sound and vibration damping materials also used wet ground and dry ground mica powder.(4) Mold Release Agent in Moulding Curing of Rubber: In many cases, the moulding curing of rubber will not use metal molds or similar molds. The performance of mold release agent will impose direct impact on production. For example, air bags are used into the moulding curing of tire and if at this time high-performance mold release agent is not used, then adhesion of molds and products will be bound to happen, which will not only damage the mold, but also cause a large number of defective products and then bring enormous harm on production.Such mould release agent commonly uses lubricating grease, organic silicon, organic fluorine and other materials. As solid lubricants plays an essential role, so the modern type of this mould release agent will generally add in mica. Wet ground mica powder, with perfect flaky and thin chip, has a great ability of covering and shielding the surface of the mold. Besides, the surface of wet ground mica chip is smooth, which can effectively prevent adhesion of materials. Wet ground mica has a high rate of purity, which makes the content of harmful impurities binding rubber and mold becomes quite low, therefore, it is quite applicable. Impurities, such as quartz, feldspar and other minerals powder, are rough in surface and are not flaky in structure, which is one of the important reasons for the difficulty of stripping. While, for the difficulty of stripping with dry ground mica powder, another reason is that the rough surface of the mica particle itself makes it very adhesive. After adding wet ground mica, a kind of air exhaust passage will be formed between the mold and the rubber, thus preventing the gas’ retention within the gap and then improving the physical appearance of products. 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.(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 powder that 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.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.


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