What’s the Properties and Application of Silicone Resin Powder?

Silicone resin powder also called light diffusion agent, it make of polymethsilsesesquioxane organosilicone. The general particle size range of polymethylsilsesquioxane organosilicon spherical powder is 0. 5%. In the range of 8 ~ 10 μ m, each difference is 0. 5%. Specifications and varieties can be supplied separately at 5 μ m, and users can choose different sizes of silicone spherical powders according to their needs. They all have the characteristics of chemical resistance, stable heat resistance, ultraviolet resistance, weather resistance and improving dispersive processing. Compared with other organic spherical powders, such as polymethyl methacrylate (PMMA) powder, polymethylsilsesquioxane silicone spherical powder will not appear black spots due to local high temperature during thermoplastic processing, and the products will not yellowing for a long time. Compared with inorganic powders such as silicon dioxide, there is no problem of difficult compatibility with plastic resin, and the microspheres will not be broken by extrusion and shearing in many processing processes, maintaining the initial physical properties of organic silicon spherical powder. In this paper, the properties and functional applications of silicone spherical powder are introduced as follows.

1 properties of organo silicone resin powder

Silicone spherical micropowder is a kind of powdered silicone resin, which is shown in figure 1 by scanning electron microscope (SEM). There are two main preparation methods of powdered silicone resin: one is to obtain spherical micropowder by direct hydrolysis and condensation of siloxane monomer, and the other is to obtain amorphous powder from ready-cured bulk silicone resin by mechanical pulverization, including soluble methyl MQ silicone resin powder, etc. The shape, nature, and function of the two are different.

Spherical silicone resin micro-powder is a kind of solid powder with truly spherical and narrow particle size distribution (see figure 2). Its chemical structure is an insoluble and infusible curing resin with dense cross-linking trifunctional composition. Spherical silicone resin micro-powder has excellent properties such as low density, heat resistance, lubricity, hydrophobicity and so on. Mainly used in plastic, rubber, paint, ink, cosmetics, and liquid crystal display backlight module, LED lighting light diffusion plate/film, thermal printing, etc., in order to improve its lubricity, optical properties, hydrophobicity, anti-fouling, release, flame retardancy, and other properties.

The varieties of spherical silicone resin micro-powder include stable non-reactive type (mainly composed of polymethylsilsesquioxane) and crosslinking reactive type (mainly composed of epoxy group, amino group, methacryloxy group, sulfhydryl group, vinyl group and so on. Polysilicone sesquioxane, as well as functional modification (such as hydrophilic type, UV absorption type) and other types.

2 The difference between organic and inorganic resin powders

Organosilicon contains Si-O-Si bond, which is the same as silicate and other inorganic structural units, but also contains silane genes and has the properties of some organic compounds. Because of this duality, silicone polymers not only have the properties of heat resistance, fire resistance and weather resistance of general inorganic materials but also have the characteristics of organic polymers such as insulation, thermoplasticity and softness. the controllable molecular structure gives organic silicon materials the advantages of both inorganic and organic materials.

3 Application in functional plastic masterbatch

3. 1 silicone resin powder used for light diffusion masterbatch

It can be added to polycarbonate (PC) and poly (vinyl alcohol). Styrene (PS), PMMA and other transparent plastics to provide excellent light diffusion properties, with a good balance of impact strength, haze and light transmittance. Compared with inorganic micro-powder light diffuser, it has the advantages of low specific weight, good dispersibility, good lubricity, especially high light transmittance, and compared with other organic micro-powder light diffuser, such as PMMA powder, organosilicon light diffuser has obvious advantages such as higher haze efficiency, more outstanding heat resistance, stable color quality, no yellowing, no black spot, finer control of particle micro-shape, narrower particle size distribution and so on. The content of light diffuser (organosilicon spherical powder) in the photodiffusion masterbatch depends on the equipment and process of the user, generally 2 ~ 10% is suitable, the content is too low and uneconomical, too high content is not conducive to dispersion, and it is easy to produce specific gravity gradient difference in the hopper. If the granulation equipment uses the extruder with side feeding device, the advance mixing equipment and process can be saved, but the process adjustment is slightly complicated. Please pay attention to the following points in the mixing process:

(1) it is better to use a double-cone mixer with a rotational speed of tens of revolutions per minute. If you use a high-speed mixer, use a low-speed mixer.

(2) add the plastic particles to the mixer first, and then add the weight of plastic particles to 0. 5%. 1% ~ 0. 3% dimethyl silicone oil is used as mixed diffusion oil, the surface of plastic particles is wet on, and then organosilicon spherical micro-powder light diffuser is added. The powder is uniformly adsorbed on the surface of plastic particles by silicone oil, mixed and discharged evenly, and granulated by extruder.

(3) the addition amount of dimethyl silicone oil can be controlled to wet the surface of plastic particles, and it is easy to cause a single screw to slip without eating. It is generally appropriate to use 500 viscosity in summer and 350 viscosity in winter.

3. 2 for anti-adhesive masterbatch

Silicone resin powder can be added to biaxially oriented polypropylene.
Transparent plastics such as (BOPP), biaxially oriented poly (ethylene terephthalate) (BOPET), chlorinated polypropylene / chlorinated polyethylene (CPP/ CPE), isotactic polypropylene / isotactic polyethylene (IPP/ IPE), plastic optical fiber (POF) are prepared into high-end anti-adhesive plastic masterbatches with effective components of 3% ~ 7%. The ultra-transparent characteristics of organosilicon spherical powder can minimize the effect of anti-adhesive on the optical properties of thin films, and realize the application of ultra-transparent thin films. Give the anti-adhesive film layer excellent optical vision performance: high light transmittance, gloss, good anti-adhesive effect. Suitable for the production of crystal film, ultra-low haze BOPP film, anti-adhesive layer does not yellowing, processing and use of the anti-sticking role of the powder does not fall off.

3. 3 for other engineering plastics modified masterbatch

Silicone resin powder can be added to polyphenylene sulfone.
Various engineering modified plastics such as (PPS), polyvinyl chloride (PVC), PS, PC, nylon 66 (PA66), phthalonitrile / butadiene / styrene terpolymer (ABS) have the functions of flame retardant and smoke suppression, internal and external lubrication, improving the mechanical energy of engineering plastics and improving the processability of plastic products. It can be used as smoke suppressant, dry lubrication dispersant, high temperature resistance and high permeability anti-adhesion agent, reducing glass fiber exposure agent and other functional auxiliaries, so as to promote the improvement of the functional indexes of various modified engineering plastics.

4 Application in the formulation process of plastic products

Most plastic building materials and building plastic products contain a large proportion of filled and modified inorganic powder, which brings the problems of uneven dispersion, extrusion, low efficiency, mechanical property decline, poor surface property of products, etc. , because of its unique inorganic and organic properties, it can solve the problem that the inorganic powder can not be uniformly dispersed in the plastic resin. 5 ~ 1 phr of silicone spherical micro-powder can obviously solve the above production, production process problems and improve the physical and properties of filler building plastic products.

5 Application in functional plastic film

Silicone resin micro-powder is very suitable for the preparation of precision coating light diffusion film; in addition to excellent light transmittance and haze balanced optical properties, silicone spherical micro-powder has quite narrow particle size distribution, and there are various particle size specifications to choose from, which is more suitable for fine coating a variety of light diffusion films with different coating thickness. its UV irradiation resistance and aging resistance can prolong the service life of the light diffusion film. Silicone resin powder is also suitable for high-end anti-adhesive film with high transparency and shedding resistance, which can be produced by two-way stretching method.

6 conclusion

Silicone spherical powder used to be mainly supplied by foreign multinational companies, high price, long order cycle and other factors affect its application in China and related fields. With the rapid development of the photoelectric industry in China, more and more attention has been paid to the energy-saving index, functional products and quality requirements of the products At the same time, a batch of organic silicon spherical micro-powder research and development manufacturers with their own knowledge and intellectual property rights, such as Wanda Chemical Co., Limited have also emerged in China to provide more, more cost-effective silicone spherical powder supply market, in function, plastic additives to help china-made photoelectric products to maintain international, competitive advantage. With the market segmentation and multi-functional, silicone balls, shaped micro-powder will be in light diffusion, film anti-stick, engineering modified plastics, etc. , the industry has been more widely used.

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