Coating processes – With post-treatment of coating or coating material – Heating or drying
Patent
1998-12-11
2000-02-15
Cameron, Erma
Coating processes
With post-treatment of coating or coating material
Heating or drying
4273935, 427409, 4274121, B05D 714, C08G 1862
Patent
active
060250313
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a coating composition consisting of at least three components (I), (II) and (III) which is based on a polymer which contains hydroxyl and acid groups and is dispersed or dissolved in one or more organic, optionally water-dilutable solvents, on one or more isocyanato-containing crosslinking agents and on one or more dispersions of polymers which contain hydroxyl and acid groups, including as constituent essential to the invention at least one aqueous dispersion, prepared in accordance with a specific method, of a hydrophilicized polymer resin HP.
The present invention additionally relates to a process for the preparation of these coating compositions and to the use of the coating compositions in repair coating (refinishing) and for the coating of plastics, and also as topcoat or filler.
BACKGROUND OF THE INVENTION
For ecological and economic reasons the paint industry is attempting to replace as large as possible a portion of the organic solvents employed in paints by water. In the context of automotive finishing in particular, there is a great requirement for aqueous coating materials. This applies both to the area of production-line automotive finishing and to the area of automotive refinishing.
EP-B-0 358 979 discloses aqueous two-component polyurethane coating compositions which comprise a hydroxyl-containing polyacrylate resin dispersed in water, and a polyisocyanate component. These coating materials described in EP-B-0 358 979, however, exhibit great disadvantages in respect of gloss, relaxation (low graininess of the coating), boil-mark tendency and, resulting therefrom, spray safety, and in respect of weathering resistance, especially in respect of resistance under constant condensation conditions (40 degrees C., 240 hours), processibility (drop in viscosity and inadequate pot life) and hardness.
The object of providing an aqueous coating composition which has improved properties and/or which gives improved coating films relative to the aqueous two-component polyurethane coating compositions known from EP-B-0 358 979 is largely achieved by the as yet unpublished German Patent Application P 44 21 823.0. Nevertheless, even using the 3-component systems in accordance with the as yet unpublished German Patent Application P 44 21 823.0 as automotive refinishes, there are still problems on the fully cured coatings as a result of boil marks, grey haze and/or textured surfaces, caused by poor leveling of the coating compositions.
The object which results from this, namely to provide coating systems for automotive refinishing which under the conditions of automotive refinishing lead to coatings which exhibit no surface problems, such as boil marks or textures, and no impairment of the optical quality, such as grey haze, is achieved by the 3-component coating composition described in the as yet unpublished German Patent Application P 195 42 626.
These 3-component coating compositions are characterized in that in one or more organic, optionally water-dilutable solvents and contains hydroxyl groups and acid groups which can be converted into the corresponding acid anion groups, and/or one or more organic, optionally water-dilutable solvents and contains hydroxyl groups and acid groups which can be converted into the corresponding acid anion groups, and/or in one or more organic, optionally water-dilutable solvents and contains hydroxyl groups and acid groups which can be converted into the corresponding acid anion groups, and/or that a 50% strength solution of the binder (A) in ethoxyethyl propionate has a viscosity of <=6.0 dPa.s at 23.degree. C., and/or polyisocyanate (F1) which is optionally dispersed or dissolved in one or more organic solvents, and/or optionally at least one further crosslinking agent, consisting of at least one epoxide compound (F2) having at least two epoxide groups per molecule and/or optionally at least one amino resin (F3), and and/or (A4) in aqueous dispersion.
The coating compositions described in the as yet unpublished
Grandhee Sunitha
Lettmann Bernhard
Mayer Bernd
Nienhaus Egbert
Rink Heinz-Peter
BASF Coatings AG
Cameron Erma
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