Fluorspar-based filler and method for making the same

1. A covering agent that includes a filler material, said filler material including metal fluoride particles, said metal fluoride particles including a metal fluoride compound that is at least partially coated with a silicon compound, said metal fluoride particle including about 50-99.9 weight percent of said metal fluoride compound and about 0.1-50 weight percent of said silicon compound, said silicon compound includes silicon dioxide.

2. The covering agent as defined in claim 1 , wherein said covering agent having a sheen valve at 85° of less than about 2.

3. The covering agent as defined in claim 1 , wherein said covering agent is a latex paint.

4. The covering agent as defined in claim 1 , wherein said covering agent includes a polymer having interpolymerized units that include one or more units derived from styrene, methyl styrene, vinyl, or combinations thereof, and one or more units derived from acrylates, methacrylates, acrylonitrile, or combinations thereof.

5. The covering agent as defined in claim 1 , wherein said covering agent includes a pigment.

6. The covering agent as defined in claim 5 , wherein a weight ratio of said filler material to said pigment is about 0.1-4:1.

7. The covering agent as defined in claim 5 , wherein said pigment includes titanium dioxide.

8. The covering agent as defined in claim 5 , wherein said filler material functions at least partially as a pigment extender.

9. The covering agent as defined in claim 8 , wherein said pigment extender includes said filler material, said filler material includes metal fluoride particle and nepheline syenite, a weight ratio of said metal fluoride particle to said nepheline syenite is about 0.1-1:1.

10. The covering agent as defined in claim 1 , wherein said filler material includes one or more compounds selected from the group consisting of calcium carbonate, gilders whiting talc, barytes, magnesium silicates, aluminum silicates, diatomaceous earth, china clay, asbestine, silica, nepheline syenite and mica.

11. The covering agent as defined in claim 1 , wherein said metal fluoride of said metal fluoride particle includes calcium fluoride.

12. The covering agent as defined in claim 11 , wherein said metal fluoride of said metal fluoride particle includes at least about 70 weight percent calcium fluoride.

13. The covering agent as defined in claim 1 , wherein said metal fluoride particle includes about 65-85 weight percent of said metal fluoride compound and about 15-35 weight percent of said silicon compound.

14. The covering agent as defined in claim 13 , wherein said metal fluoride particle includes about 65-80 weight percent of said metal fluoride compound and about 20-35 weight percent of said silicon compound.

15. The covering agent as defined in claim 1 , wherein said metal fluoride particle is white and has a Tappi brightness value of at least about 84.

16. The covering agent as defined in claim 15 , wherein said metal fluoride particle has a Tappi brightness value of about 84-91.

17. The covering agent as defined in claim 1 , wherein said metal fluoride particle has average specific surface area of up to about 120 m 2 /g.

18. The covering agent as defined in claim 1 , wherein a majority of an outer surface of said metal fluoride compound is coated with said silicon compound.

19. The covering agent as defined in claim 1 , wherein at least 80 percent of said outer surface of said metal fluoride compound is coated with said silicon compound.

20. The covering agent as defined in claim 1 , wherein an average particle size of said metal fluoride particle is less than about 100 microns.

21. The covering agent as defined in claim 1 , wherein an average particle size of said metal fluoride particle is about 5-30 microns.

22. The covering agent as defined in claim 1 , wherein the covering agent is a paint, stain, varnish, primer, lacquer, or sealant.