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Yuan Lei tells you | Mineral fillers and their role in coatings

Release time:

2024-01-29 09:35

 

Yuan Lei tells you | Mineral fillers and their role in coatings

 

Filler is also called filler, that is, added to the material (suchPlastics, rubber, adhesives, papermaking, coatings, chemical fibers, power electronics, ceramics, glass, refractory materials, cementitious materials, inks, etc.).is a relatively inert material,It can reduce the cost, improve the performance and improve the process characteristics of the material.

 

Fillers can be divided into two types: one is to reduce costs, adding cheap materials to higher-priced materials, and does not change the performance of the material; the other is a functional filler with special functions, such as Electrical insulation, conductive, magnetic, flame retardant, antistatic and reinforcing, etc., after adding the material performance is improved.

 

Classification of mineral fillers

 

Filler wide application field, variety, with a variety of classification methods. According to the material composition is divided into organic filler and inorganic filler, or mineral filler, plant filler, synthetic filler three categories.

 

1
Classification by geometric form of filler

 

Particles are the form of fillers, and the morphology of particles is not very regular, but the geometric morphology of different fillers has significant differences, and the particle morphology of different fillers has a significant impact on the performance of the product. Classification by geometric form of mineral particles

 

 

2
Classification by chemical composition of filler

 

In the filler modification, the chemical composition of the filler determines the nature of the filler, especially when the material is given functionality, the chemical composition of the filler plays a decisive role. American scholars Hurlbut divided the chemical composition of fillers into four categories: oxides, salts, elemental and organic matter.

 

Theoretically, there are many kinds of powder materials that can be used as a filler for plastics. However, there are not many varieties that have no obstacles in terms of economy and technology, mainly calcium carbonate, talc, kaolin, mica powder, wollastonite powder, graphite, brucite powder, barite powder or precipitated barium sulfate, wood powder and metal powder with special functions.

 

3
Classification by application of filler

 

Can be used as a mineral filler of many kinds of minerals, the use is also very wide, according to the application field of filler can be divided into plastic filler, rubber filler, paper filler, paint filler, paint filler, such as more than 10 kinds of filler.

 

coating mineral filler

 

Coating is a finishing material made of grease, synthetic resin, rubber, polymer binder as the main raw material. The basic components of the coating: film-forming substances, pigments, including extender pigments (fillers), auxiliary materials (additives), dispersion medium (solvent or water). Adding fillers can not only reduce the cost, but also improve the construction performance of the coating, and improve the water resistance, wear resistance and temperature resistance of the coating.

 

Commonly used body pigments: calcium carbonate, barium sulfate, kaolin, silica, talc, wollastonite, mica, asbestos, etc.

 

In addition, the main physical characteristics of the particle size, particle shape, oil absorption, density and modification (surface treatment, calcination, etc.) of the extender pigment will affect the performance of the coating.

 

The role of fillers in coatings

 

The use of fillers in coatings can play a role in:

 

1. Play the role of skeleton and filling in the coating, increase the thickness of the paint film, and make the paint film plump and solid.

 

2, can adjust the rheological properties of the coating.

 

Improve the mechanical strength of the paint film, such as improving wear resistance and durability.

 

4. Adjust the optical properties of the coating and change the appearance of the coating film, such as extinction.

 

5. The film-forming material chemically reacts to make it into a whole, so that the film can effectively block the penetration of light, improve its water resistance and weather resistance, and extend the service life of the film.

 

6, as a filler in the coating, reduce the amount of resin, reduce production costs.

 

7, the chemical properties of the coating plays an auxiliary role, such as enhanced rust, moisture resistance, flame retardancy and so on.

 

Oil absorption value of non-metallic mineral fillers commonly used in coatings (g/100g)

 

 

Fillers commonly used in coatings

 

Fillers commonly used in coatings are calcium carbonate (heavy calcium, light calcium, nano calcium), barite powder (barium sulfate), talcum powder, kaolin (porcelain land), porous powder quartz (silica), white carbon black, precipitated barium sulfate, mica powder, wollastonite, bentonite, etc.

 

Calcium carbonate

Calcium carbonate is an important filler in coating production. Calcium carbonate plays a role in the filling of the skeleton and the bottom plate (steel plate, wood) in the paint film, and enhances the deposition and permeability of the paint film.

 

Talcum powder

Talcum powder is a general-purpose filler in solvent-based coatings. At present, it is used in various primers, intermediate coatings, road marking paints, industrial coatings and internal and external architectural coatings.

 

Kaolin

Kaolin is one of the fillers widely used in foreign coating industry. The kaolin commonly used for coatings includes ultrafine kaolin, calcined kaolin, activated kaolin (surface modified), etc. Kaolin can be used in various coatings, but mainly in water-based architectural coatings.

 

Graphite

Natural graphite can be used in steel structure maintenance coatings because of its flake structure and good hiding rate. Its good conductivity and black color make it can be used in electronic computer electric shielding coatings, which can contain up to 75% graphite. Another use is anti-static floor coatings. It can be used in heat-resistant coatings, primers, sealing coatings and water-resistant coatings. Due to its good light resistance, it can be used in automobile paints as an effect pigment.

 

Wollastonite

Wollastonite is mainly composed of calcium metasilicate (CaSiO3), which has a needle-like structure, good brightness, refractive index (1.62) and relatively low oil absorption (20~26g/100g)

 

Needle-like structure of wollastonite (aspect ratio of 10:1~20:1), in the coating can play the role of flat agent, improve the mechanical strength of the coating film, sometimes in the reinforced coating instead of harmful asbestos. Coatings are generally used for more fine grade (such as 325 mesh) and fine grade (10um) wollastonite powder, because it is conducive to the hiding power of the coating. Can be used for oily architectural coatings, sound absorption (sound insulation) coatings, road marking paint, polyvinyl acetate latex paint, etc. The surface-treated wollastonite can be used in industrial alkyd, epoxy and other anti-corrosion coatings to improve the corrosion resistance of metal primers and partially replace active anti-rust pigments.

 

-THE END-

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