How to choose filler of powder coating?
Powder coating is a solid powdered synthetic resin coating composed of solid resin, pigment, filler and additives.It is different from ordinary solvent-based coatings and water-based coatings,dispersion medium of powder coasting is air,not solvents or water.
The filler for powder coating are required the following features:
1.Density:the bigger density,the lower the coverage of powder coating
2.PSD(Particle Size Distribution):The PSD of filler is very important,if there are bigger particles in it,the cured coating will have poor flatness and rough appearance, and will also cause great wear on the screw.
3.Chemical properties:filler must have a certain chemical inertness,not to react with any element of the powder formula.
4.Purity:more impurity will influence surface decorative of coating.
5.Whiteness:it is better to choose white filler,then it can reduce the amount of titanium dioxide.
6.Water percentage:LOI should be less than 0.5%,if more water,curing reaction and agglomeration will happen and influence the mobility of powder.
The ordinary filler for powder coatings are as follows:
1、Mica powder
Mica powder is natural powder,with mohs hardness 2-3.5 and monoclinic crystal structure,it is good insulation materials.Adding mica powder into coating can significantly improve the UV resistance and weather resistance of the coating film.
2、Talcum powder
Talcum powder,mohs hardness:1.0,as filler,It has influence on the melt fluidity and leveling of powder coatings,also can increase the hardness,weather and corrosion resistance of coating film.
3、Quartz powder
Mohs hardness:7.0,acid-resistant, not alkali-resistant, wear-resistant,non-toxic and good electrical insulation makes it can improve the hardness and heat resistance of the coating.
4、White Carbon Black
White Carbon Black has properties of light resistance, high temperature resistance, acid resistance and alkali resistance and mohs hardness 5-6,it can mattify,anti-sagging and improving powder coating fluidity.
5、Calcium carbonate
Calcium carbonate,with mohs hardness 3.0,is a high whiteness, high purity, high filling content filler.Added in coating,it can improve the leveling, gloss and weather resistance of coatings。
6、Barium sulfate
Barium sulfate,with mohs hardness 3.0-3.5,is a high density, high hardness and low oil absorption heavy filler.Barium sulfate can improve the wear resistance and scrub resistance of the coating
7、Wollastonite
Wollastonite,with mohs hardness 4.5-6.0,also is a high density, high hardness and low oil absorption powder.
8、Kaolin
Kaolin is a kind of white filler with flake structure,high whiteness and low oil absorption.Its mohs hardness is 1-2, in powder coating,kaolin can improve the leveling and gloss of the coating.
9.White corundum
White corundum is high hardness (mohs hardness:9.0)translucent powder.In order to meet with the requirement of enduser,white corundum is used as filler of powder coating to improve the wear resistance to extend working life.Besides it is white color,which is easy to coloring.
10.Green carborundum
Green carborundum is green color powder,with higher mohs hardness about 9.4 than white corundum,but because of its color and high cost,only the endusers require to use the hardness filler,the producers will buy green carborundum as filler of powder coating.
