Process for preparing an aqueous powder coating dispersion and using the same
First Claim
1. An aqueous powder coating dispersion, comprising the result ofdispersing a solid pulverulent component A into an aqueous component B to provide an aqueous dispersion of a powder coating composition having a glass transition temperature of from 20 to 90°
- C., a viscosity of from 10 to 1000 mPas at a shear rate of 500 s-1, and a solids content of from 20 to 40% by weight,subjecting said aqueous dispersion of a powder coating to a grinding process while maintaining a temperature of from 0 to 60°
C. to provide an aqueous powder coating dispersion having a solids content of from 20 to 40% by weight,wherein solid pulverulent component A is a powder coating composition comprisinga) at least one epoxide-containing binder comprising from 30 to 45% by weight of glycidyl-containing monomers,b) at least one crosslinking agent, andcomponent B is an aqueous dispersion comprisinga) at least one nonionic thickener.
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Abstract
The present invention relates to an aqueous powder coating dispersion comprising a solid, pulverulent component A and an aqueous component B, in which component A. is a powder coating comprising
a) at least one epoxide-containing binder with a content of from 30 to 45%, preferably from 30 to 35%, of glycidyl-containing monomers and, if desired, with a content of aromatic vinyl compounds, preferably styrene,
b) at least one crosslinking agent, preferably straight-chain aliphatic dicarboxylic acids and/or carboxy-functional polyesters, and
c) if desired, catalysts, auxiliaries, typical powder coating additives, such as degassing agents, levelling agents, UV absorbers, free-radical scavengers and antioxidants,
and component B. is an aqueous dispersion comprising
a) at least one nonionic thickener and
b) if desired, catalysts, auxiliaries, defoaming agents, dispersion auxiliaries, wetting agents, preferably carboxy-functional dispersants, antioxidants, UV absorbers, free-radical scavengers, biocides, small quantities of solvent and/or hygroscopic agents.
50 Citations
23 Claims
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1. An aqueous powder coating dispersion, comprising the result of
dispersing a solid pulverulent component A into an aqueous component B to provide an aqueous dispersion of a powder coating composition having a glass transition temperature of from 20 to 90° - C., a viscosity of from 10 to 1000 mPas at a shear rate of 500 s-1, and a solids content of from 20 to 40% by weight,
subjecting said aqueous dispersion of a powder coating to a grinding process while maintaining a temperature of from 0 to 60°
C. to provide an aqueous powder coating dispersion having a solids content of from 20 to 40% by weight,wherein solid pulverulent component A is a powder coating composition comprising a) at least one epoxide-containing binder comprising from 30 to 45% by weight of glycidyl-containing monomers, b) at least one crosslinking agent, and component B is an aqueous dispersion comprising a) at least one nonionic thickener. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21)
- C., a viscosity of from 10 to 1000 mPas at a shear rate of 500 s-1, and a solids content of from 20 to 40% by weight,
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12. A process for the preparation of an aqueous powder coating dispersion comprising
preparing an aqueous dispersion of a powder coating composition by dispersing a solid pulverulent component A into an aqueous component B, the resulting aqueous dispersion having a glass transition temperature of from 20 to 90° - C., a viscosity of from 10 to 1000 mPas at a shear rate of 500 s-1, and a solids content of from 20 to 40% by weight, and
grinding the aqueous dispersion of a powder coating composition while maintaining a temperature of from 0 to 60°
C. to provide a ground aqueous dispersion of a powder coating,establishing a pH of from 4.0 to 7.0 in the ground aqueous dispersion of a powder coating, and filtering the ground aqueous dispersion of a powder coating dispersion to provide an aqueous powder coating dispersion, wherein solid pulverulent component A is a powder coating composition comprising a) at least one epoxide-containing binder comprising from 30 to 45% by weight of glycidyl-containing monomers, b) at least one crosslinking agent selected from the group consisting of straight chain aliphatic dicarboxylic acids, carboxy-functional polyesters, and mixtures thereof, and component B is an aqueous dispersion comprising a) at least one nonionic thickener. - View Dependent Claims (13)
- C., a viscosity of from 10 to 1000 mPas at a shear rate of 500 s-1, and a solids content of from 20 to 40% by weight, and
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22. A process of coating an article with an aqueous dispersion of a powder coating composition, comprising
providing an aqueous powder coating dispersion comprising the result of subjecting an aqueous dispersion of a powder coating composition comprising at least one crosslinking agent, the aqueous dispersion having a glass transition temperature of from 20 to 90° - C., a viscosity of from 10 to 1000 mPas, and a solids content of from 20 to 40% by weight, to a grinding process while maintaining a temperature of from 0 to 60°
C. , andapplying the aqueous dispersion of a powder coating composition to an article by means of electrostatically assisted rotation or pneumatic application. - View Dependent Claims (23)
- C., a viscosity of from 10 to 1000 mPas, and a solids content of from 20 to 40% by weight, to a grinding process while maintaining a temperature of from 0 to 60°
Specification