Pseudoplastic powder lacquer slurry free of organic solvents, method for production and the use thereof

a technology of organic solvents and powder lacquer, which is applied in the field of new powder clearcoat slurry, can solve the problems of unsatisfactory date, unsatisfactory environmental problems, and powder clearcoat materials still show weaknesses in chemical resistance and yellowing, and achieve good homogeneity of the resulting particles

Inactive Publication Date: 2005-01-06
ROCKRATH ULRIKE +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

A further object of the present invention was to find a novel process for preparing powder clearcoat slurries which continues to ensure the essential advantage of the mixing of the components in solution: the very good homogeneity of the resulting particles.

Problems solved by technology

These give rise to numerous environmental problems owing to their solvent content.
The results to date, however, have not been satisfactory; in particular, powder clearcoat materials still show weaknesses with regard to chemical resistance and yellowing.
And yet it is not possible to do without wet grinding, since otherwise the coarse particle fraction of the powder clearcoat slurry is not reduced in size.
In the course of this filtering operation, even very small coarse particle fractions (particle size>10 μm) result in clogging of the filters, so that the production process has to be stopped—a disadvantage both technically and economically.
For stabilization, it is necessary, in addition to the ionic stabilization, to employ external emulsifiers as well—generally polyethylene oxide adducts, which decrease the resistance of the coating to water and moisture.
Moreover, these known powder clearcoat slurries still always include certain amounts of organic cosolvents or leveling agents, which cannot be removed since they are essential to the leveling properties of the partly dried film.
Furthermore, the patent does not give any teaching as to how the problem of filterability in connection with powder clearcoat slurries might be solved.
It has been found that even this powder clearcoat slurry must be filtered prior to its application and in the course of such filtration gives rise to problems similar to those encountered with the known powder clearcoat slurries.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example 1

The Preparation of a Solution Polyacrylate Resin

445.3 parts by weight of methyl ethyl ketone (MEK) were introduced into a reaction vessel and heated to 80° C. The initiator solution, consisting of 47.6 parts by weight of TBPEH (tert-butyl perethylhexanoate) and 31.1 parts by weight of MEK, and the monomer mixture, consisting of 183.3 parts by weight of tert-butyl acrylate, 71.4 parts by weight of n-butyl methacrylate, 95.2 parts by weight of cyclohexyl methacrylate, 121.4 parts by weight of hydroxyethyl methacrylate and 4.76 parts by weight of acrylic acid, were metered into this initial charge at 80° C. with stirring over the course of 5 h from two separate feed vessels. The reaction mixture was then heated to 80° C. for two hours, and a fraction of the volatile components of the reaction mixture was stripped off under reduced pressure at 500 mbar for 5 h. The resin solution was then cooled to 50° C. and discharged.

The resin solution had the following characteristics:

Solids:...

preparation example 2

The Preparation of a Blocked Polyisocyanate Crosslinker

837 parts of isophorone diisocyanate were introduced into an appropriate reaction vessel, and 0.1 part of dibutyltin dilaurate was added. A solution of 168 parts of trimethylolpropane and 431 parts of methyl ethyl ketone was then run in slowly. As a result of the exothermic reaction, the temperature rose. After it had reached 80° C., the temperature was kept constant by external cooling and the rate of addition of the feed stream was reduced slightly if necessary. After the end of the feed stream, the mixture was held at this temperature for about 1 hour until the isocyanate content of the solids had reached 15.7% by weight based on the solids. The reaction mixture was subsequently cooled to 40° C. and a solution of 362 parts of 3,5-dimethylpyrazole in 155 parts of methyl ethyl ketone was added over the course of 30 minutes. After the reaction mixture had heated up to 80° C., owing to the exothermic reaction, the temperature ...

example 1

The Preparation of an Inventive Powder Clearcoat Slurry

975.1 parts by weight of the acrylate resin solution from preparation example 1 and 567.7 parts by weight of the crosslinker solution from preparation example 2 were mixed at room temperature in an open vessel for 15 minutes with stirring. Then 10.9 parts by weight of Cyagard® 1164 L (UV absorber from Cytec), 10.9 parts by weight of Tinuvin® liquid 123 (sterically hindered amine “HALS” from Ciba Geigy) and 9.5 parts by weight of N,N-dimethylethanolamine were added and the resulting mixture was stirred at room temperature for a further two hours. The mixture was then diluted with 645.9 parts by weight of deionized water in small portions. After an interval of 15 minutes, a further 780.0 parts by weight of water were added. This gave an aqueous emulsion of low viscosity with a theoretical solids content of 37% by weight, which was stirred at room temperature for a further 48 hours. The amount of liquid evaporated off was supple...

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Abstract

A pseudoplastic powder clearcoat slurry which is free from organic solvents and comprises solid and / or highly viscous, particles which are dimensionally stable under storage and application conditions and have an average size of from 0.8 to 20 μm, at least 99% of the particles having a size ≦30 μm, which is preparable by 1) emulsifying an organic solution comprising binder and crosslinking agent to give an emulsion of the oil-in-water type, 2) removing the organic solvent or solvents, and 3) wet grinding the resulting slurry; and also the use of the powder clearcoat slurry to produce clearcoats for automotive OEM finishing and automotive refinish, for furniture coating and for industrial coating, including coil coating, container coating and the coating of electrical components.

Description

BACKGROUND The present invention relates to a novel powder clearcoat slurry, free from organic solvents, which possesses pseudoplasticity. The present invention also relates to a novel process for preparing this powder clearcoat slurry. The invention relates not least to the use of the novel powder clearcoat slurry for producing clearcoats for the automotive sector and for the industrial sector. For the coating of automobile bodies, preference is given today to the use of liquid coating materials, i.e., spray paints. These give rise to numerous environmental problems owing to their solvent content. The same applies to cases where waterborne clearcoat materials are used, since they still always contain certain amounts of organic solvents. Waterborne clearcoat materials of this kind are known from the German patent DE 196 23 371 A1. Directly after application, the conventional waterborne clearcoat materials do not dry to a powder but instead flow out to form a continuous film. They...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B05D7/24B05D7/14C08G18/08C08G18/62C08G18/80C08J3/07C08L75/04C09D5/00C09D5/02C09D133/00C09D133/06C09D175/04C09D201/00
CPCC08G18/0866C08G18/6254C08G18/8025C08G18/807C08G2150/20C08J3/07C09D175/04C08L75/04C09D5/02C09D133/066C08L2666/14C09D5/03C09D7/44C09D133/08
Inventor ROCKRATH, ULRIKEOTT, GUNTHERBERG, JANJUNG, WERNER-ALFONSWOLTERING, JOACHIM
Owner ROCKRATH ULRIKE
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