Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-03-28
2004-06-01
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S108000, C525S119000, C525S438000, C525S530000
Reexamination Certificate
active
06743867
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to coating compounds and the use thereof in the preparation of multi-layer lacquers, for example, in the automotive sector, particularly in the preparation of two-layer lacquers of the base lacquer/clear lacquer type.
BACKGROUND OF THE INVENTION
Coating compounds curing with ester formation and based on a combination of epoxy-functional component and carboxyl-functional component are known, for example, from EP-A-0 598 280. Generally speaking, coating compounds of this kind are characterised by good resistance to chemicals and acids of the coatings prepared therefrom and stoved, and they are therefore particularly suitable as clear lacquers or top coat lacquers in automotive OEM finishing.
The object of the invention is the provision of coating compounds crosslinkable by reaction of carboxyl and epoxy groups which are improved in terms of resistance to solvents, particularly resistance to super-grade petrol, particularly in the case of understoved coatings. It should be possible to use the coating compounds to be found as clear lacquer coating compounds for the production of base lacquer/clear lacquer two-layer lacquers, of the kind customarily found particularly in the field of automotive finishing.
SUMMARY OF THE INVENTION
The object is achieved by curable coating compounds containing a binder/crosslinking agent system, organic solvents and/or water, and optionally pigments and/or fillers and optionally further conventional lacquer additives, wherein the binder/ crosslinking agent system contains 20 wt. % to 80 wt. % of one or more carboxyl-functional components A) selected from carboxyl-functional (meth)acrylic copolymers and/or carboxyl-functional polyesters the carboxyl functionality of which corresponds in each case to an acid value from 15 to 300 mg KOH/g, and 20 wt. % to 80 wt. % of one or more epoxy-functional (meth)acrylic copolymers B) with a calculated epoxy equivalent from 200 g/mole to 700 g/mole, the percentages by weight adding up to 100 wt. %, and wherein the crosslinking ratio between carboxyl groups of components A) and epoxy groups of components B) is from 1:1 to 1:3, characterised in that the epoxy-functional (meth)acrylic copolymers B) have a branched molecule structure corresponding to a calculated branching equivalent weight from 5000 g/mole to 60,000 g/mole.
The binder/crosslinking agent system of the coating compounds according to the invention contains components A) and B) as essential components and optionally optional components C), D) and/or E) explained below. For example, the coating compounds according to the invention may contain only the components A) and B) as binder/crosslinking agent system, or the binder/crosslinking agent system of the coating compounds according to the invention additionally contains the optional components C), D) and/or E).
The resin solids of the coating compounds according to the invention are formed from the sum of the resin solids or the non-volatile proportions of components A), B) and the optional components C), D) and E).
The curing of the coating compounds according to the invention is based on the chemical reaction, taking place during stoving, of the reactive groups of components A) and B) which are complementary to one another; said reaction is the addition of the carboxyl to the epoxy groups with the formation of carboxylic acid ester bonds.
DETAILED DESCRIPTION OF THE INVENTION
The coating compounds according to the invention contain, as component A), one or more carboxyl-functional components A). The carboxyl-functional component A) of the coating compounds according to the invention is carboxyl-functional (meth)acrylic copolymers and/or carboxyl-functional polyesters the carboxyl functionality of which corresponds in each case to an acid value from 15 to 300 mg KOH/g. The carboxyl-functional (meth)acrylic copolymers and/or carboxyl-functional polyesters may be urethanised and/or modified by reaction with lactones.
The optionally urethane group-containing and/or lactone-modified carboxyl-functionaries (meth)acrylic copolymers of component A) preferably have a number-average molecular weight (Mn) from 1000 g/mole to 30,000 g/mole. The optionally urethane group-containing and/or lactone-modified carboxyl-functionalised polyesters of component A) preferably have a calculated molecular weight from 500 g/mole to 4000 g/mole. The acid value is 15 to 300 mg KOH/g in each case, preferably 30 to 250 mg KOH/g.
During the preparation of the carboxyl group-containing (meth)acrylic copolymers or polyesters of component A), which may optionally contain urethane groups in each case, the carboxyl groups may be introduced directly by the use of carboxyl group-containing building blocks. Examples of suitable carboxyl group-containing monomers which may be used to construct carboxyl-group-containing (meth)acrylic copolymers include unsaturated carboxylic acids such as, e.g., acrylic, methacrylic, itaconic, crotonic, isocrotonic, aconitic, maleic and fumaric acid, half esters of maleic and fumaric acid and carboxyalkyl esters of (meth)acrylic acid, e.g. beta-carboxyethyl acrylate and adducts of hydroxyalkyl (meth)acrylates with carboxylic acid anhydrides such as, e.g., the ethyl ester of mono-2-(meth)acryloyloxy phthalic acid.
The expression (meth)acrylic is used in the present description and patent claims. This means acrylic and/or methacrylic.
During the preparation of carboxyl group-containing and optionally urethane group-containing (meth)acrylic copolymers or polyesters of component A), it is also possible, however, initially to construct a polymer containing hydroxyl groups and optionally already containing carboxyl groups and to introduce the carboxyl groups wholly or partially in a second step by reaction with carboxylic acid anhydrides. With this mode of operation, it is possible to operate with quantity ratios such that optionally sufficient hydroxyl groups remain to enable urethanisation to be carried out.
Carboxylic acid anhydrides suitable for the addition to the hydroxyl group-containing polymers which may already contain carboxyl groups include the anhydrides of di- and polycarboxylic acids such as, for example, preferably phthalic, tetrahydro-, methylhexahydro-, hexahydrophthalic and succinic anhydride.
Examples of monomers suitable for the introduction of hydroxyl groups into the optionally urethane group-containing (meth)acrylic copolymers of component A) include hydroxyalkyl (meth)acrylates such as, e.g., hydroxyethyl (meth)acrylate, and the isomeric hydroxypropyl (meth)acrylates in terms of the position of the hydroxyl group, hydroxybutyl (meth)acrylates, and reaction products of (meth)acrylic acid with the glycidyl ester of a carboxylic acid with a tertiary alpha carbon atom. The formation of the latter reaction products may take place before, during or after the polymerisation reaction.
During the preparation of the (meth)acrylic copolymers of component A), further olefinically unsaturated monomers may be used in addition to the monomers mentioned above, particularly those which, apart from an olefinic double bond, contain no further functional groups.
Examples of further suitable olefinically unsaturated monomers include, in particular, alkyl esters of (meth)acrylic acid which contain, in the alkyl part, for example 1 to 20 carbon atoms or more, such as, e.g., methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isoopropyl (meth)acrylate, isobutyl (meth)acrylate, tertiary-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, hexadecyl (meth)acrylate.
Examples of further suitable olefinically unsaturated monomers include the alkyl esters of maleic, fumaric, tetrahydrophthalic, crotonic, isocrotonic, vinylacetic and itaconic acid which contain, in the alkyl part, for example 1 to 20 carbon atoms or more.
Moreover, small proportions of monomers having at least two polymerisable, olefinic double bonds may also be used. The proportion of these monomers is pr
Drewin Claudia
Flosbach Carmen
Herrmann Friedrich
Schubert Walter
Tueckmantel Astrid
Benjamin Steven C.
E. I. du Pont de Nemours and Company
Lee Rip A
Wu David W.
LandOfFree
Coating agents which can be used for multi-layer enameling does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coating agents which can be used for multi-layer enameling, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coating agents which can be used for multi-layer enameling will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3349178