Do you know the coating application of 8 kinds of powder fillers such as calcium carbonate and talc?

Fillers in powder coatings can not only reduce costs, but also play a large role in improving the performance of coating products

Powder coatings need to consider factors such as density, dispersion properties, particle size distribution, purity and other factors when selecting fillers

1 Application of calcium carbonate in powder coatings

Calcium carbonate is divided into light calcium carbonate (precipitated calcium carbonate) and heavy calcium carbonate

In addition to being used for increments, heavy calcium is mainly used to partially replace titanium dioxide and color pigments, replace light calcium and precipitated barium sulfate, and partially replace anti-corrosion pigments

When heavy calcium is used in interior architectural paint, it can be used alone or in combination with talc

Compared with heavy calcium, light calcium has small particle size and narrow particle size distribution range, high oil absorption and brightness, and light calcium can be used where the greatest matting effect is required

2 Application of barium sulfate in powder coatings

There are two kinds of barium sulfate used as paint extender pigments, natural and synthetic.

In terms of powder coatings, precipitated barium sulfate can enhance the leveling and gloss retention of powder coatings, and has good compatibility with all colorants

Barite powder fillers are mainly used in industrial primers and automotive intermediate coatings that require high film strength, high filling power and high chemical inertness, and are also used in topcoats that require higher gloss

3 Application of mica powder in powder coating

Mica powder is composed of complex silicates, with scaly particles, excellent heat resistance, acid and alkali resistance, and has an impact on the melt fluidity of powder coatings.
It is generally used in temperature-resistant and insulating powder coatings and can be used as texture powder.
For filling
.

Among the many mica-like species, the chemical structure of sericite is similar to that of kaolin, and it has many characteristics of mica-like minerals and clay-like minerals
.
When used in coatings, it can greatly improve the weather resistance and water permeation resistance of the coating film, enhance the adhesion and strength of the coating film, and improve the appearance of the coating film
.
At the same time, the dye particles can easily enter the lattice layer of sericite powder, so as to keep the color for a long time without fading
.
In addition, sericite powder also has the function of anti-algae and anti-mildew
.
Therefore, sericite powder is a multifunctional filler with excellent price-performance ratio for coatings
.

4 Application of talc in powder coatings

Talc, also known as hydrous magnesium silicate, is directly pulverized from talc ore
.
The particles are needle-like crystals, with a greasy feeling, soft texture and low abrasiveness, good suspension and dispersibility and certain thixotropy, which have a great influence on the melt fluidity of powder coatings, and are often used in textured powders
.
It is currently used in various primers, intermediate coatings, road marking paints, industrial coatings and architectural coatings for interior and exterior use
.

Talcum powder is cheap, but it has drawbacks and is used in limited quantities
.
First, the oil absorption is larger
.
In the occasions requiring low oil absorption, it must be matched with fillers with low oil absorption and barite powder; secondly, the wear resistance is not high, and other fillers must be added to make up for the occasions requiring high wear resistance; Talc powder containing other non-metallic minerals is not suitable for exterior coatings requiring high weather resistance because impurity minerals easily react with acids (such as acid rain).
in
.

5 Application of silica in powder coating

Porous powder quartz is a kind of silica system, the safety of use is recognized, and it has been widely used in powder coatings, fire-retardant coatings, waterproof coatings, anti-corrosion coatings,
etc.
Inexpensive porous powder quartz can reduce the cost of powder coatings, and at the same time replace barium sulfate to reduce the content of soluble barium in the product and meet environmental protection requirements
.

In addition, powder coatings often use fumed silica as a loosening and anti-caking aid for powder coatings
.
Fumed silica is a multifunctional extender pigment and an excellent coating rheology control agent
.
In liquid coatings, its rheological control functions include: thickening, thixotropy, anti-sag, and edge covering; in solid powder coating systems, it promotes free flow of powders and prevents caking and fluidization
.

6 Application of Kaolin in Powder Coatings

Kaolin can improve thixotropy and anti-settling properties
.
Calcined clay has no effect on rheological properties, but can, like untreated clay, have a matting effect, increased hiding, and increased whiteness, which are similar to talc
.

Kaolin generally has high water absorption and is not suitable for improving the thixotropy of coatings, and is not suitable for preparing hydrophobic coatings
.
The particle size of kaolin products is between 0.
2-1 μm
.
Kaolin with large particle size has low water absorption, good matting effect, and kaolin with small particle size (below 1 μm) can be used for semi-gloss coatings and interior coatings
.

Kaolin can be divided into calcined kaolin and washed kaolin
.
In general, the oil absorption, opacity, porosity, hardness and Baidu of calcined kaolin are higher than those of washed kaolin
.

7 Application of hollow glass microspheres in powder coatings

Hollow glass microspheres are tiny, hollow spherical powders with the advantages of light weight, large volume, low thermal conductivity, high compressive strength, insulation, corrosion resistance, non-toxicity, good dispersibility, fluidity, and stability.

.

When applied in powder coatings, hollow glass microspheres can perform the following functions:

(1) Heat insulation, insulation and low water absorption
.
The interior of hollow glass microspheres is a vacuum or dilute gas, which has a difference in density and thermal conductivity with epoxy resin, so it has the characteristics of heat insulation and is an excellent filler for high temperature resistant powder coatings
.

(2) It can improve the physical and mechanical properties of powder coating
.
Hollow glass microsphere fillers increase the hardness and stiffness of powder coatings
.
However, the impact resistance decreases, and the decrease is related to the surface treatment of the hollow glass beads
.
If the correct coupling agent is used for pretreatment, the impact on the impact resistance of the material can be reduced
.

(3) The oil absorption rate is low
.
The oil absorption rate of different types of hollow glass microspheres per 100g is between 7mg and 50mg.
This low oil absorption rate filling material increases the filling amount in disguise during the production process and reduces the overall cost
.

8 Application of wollastonite in powder coatings

The main component of wollastonite is calcium silicate, the density is 2.
9g/cm3, the refractive index is 1.
63, the oil absorption is 30~50%, and it has a needle-like structure and good brightness
.

Powder coatings generally use natural wollastonite powder, which is processed from natural wollastonite
.
Wollastonite can be used as an extender pigment and replace some white pigments in coatings, which can cover and increase and reduce the cost of paint
.
Because of its good electrical conductivity, it is often used in epoxy insulating powder coatings
.
Wollastonite is a white needle-like structure that improves the bending and tensile properties of powder coatings
.

summary

Powder coating is an environmentally friendly coating that saves energy, resources and low pollution
.
Due to the increasing demand for energy in the world, reducing energy consumption and protecting the environment have become the main development direction
.

Therefore, the development of powder coatings with low temperature curing, high weather resistance, strong decorative properties and thin coating will be the main development direction in the future
.

Driven by the demand for powder coatings, the demand for powder fillers such as calcium carbonate, quartz, mica powder, talc, and kaolin will inevitably increase
.