Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Ethylenically unsaturated reactant admixed with a preformed...
Reexamination Certificate
2002-08-21
2003-09-30
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Ethylenically unsaturated reactant admixed with a preformed...
C524S601000, C524S604000, C524S608000, C523S522000
Reexamination Certificate
active
06627700
ABSTRACT:
This application is a National Phase Application of PCT/EP00/11616 filed on Nov. 22, 2000.
The present invention relates to novel dispersions of acrylate-modified alkyd resins. The present invention also relates to the use of the novel dispersions as novel air-drying or thermally curable coating materials, adhesives, and sealing compounds, and to the use for preparing them. The present invention additionally relates to novel coatings, adhesive films, and seals on and in primed or unprimed substrates, producible from the novel coating materials, adhesives, and sealing compounds. The present invention relates not least to the novel primed and unprimed substrates which comprise the coatings, adhesives, and seals.
Alkyd resins and modified alkyd resins, owing to their advantageous performance properties, constitute the binder base in about a third of all coating materials worldwide (in this respect see all also Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, “alkyd resins”, pages 20 to 22). It is therefore very important on ecological grounds to provide alkyd resins and especially modified alkyd resins, which can be dispersed or are soluble in water without detriment to their advantageous performance properties and which are hence able to form the basis for aqueous coating materials, adhesives, and sealing compounds.
Alkyd resins generally offer the advantage that they require no cosolvents for forming a film. A disadvantage is that they need a relatively long period of time for drying. Dispersions of acrylate copolymers, although drying more quickly, do need cosolvents for effective film formation. Acrylate-modified alkyd resins combine the two advantages of the individual components without the need to tolerate their disadvantages. It is therefore very important economically and technically to carry out further development of these alkyd resins in particular in the sense outlined above.
International patent application WO 98/13404 discloses the preparation of an aqueous dispersion of an acrylate-modified alkyd resin for which first of all a polyurethane-alkyd resin is prepared in methyl ethyl ketone. After the polyurethane-alkyd resin has been neutralized it is dispersed in water, after which the methyl ethyl ketone is removed, except for a residual fraction, by azeotropic distillation. Thereafter, at least one olefinically unsaturated monomer substantially having no reactive functional groups other than the double bond is (co)polymerized in said dispersion. These aqueous dispersions give high-quality, low-yellowing, weathering-stable, scratch-resistant, and high-gloss coatings. Nevertheless, they have the disadvantage that they can be prepared only on the basis of the comparatively expensive polyurethanes. Moreover, the possibility of varying the profile of properties of the dispersions further by the incorporation of reactive functional groups is lost. Not least, the azeotropic distillation of the relatively large amounts of solvents presents safety and economic problems.
It is an object of the present invention to provide novel aqueous dispersions of acrylate-modified alkyd resins which no longer have the disadvantages of the prior art but for whose preparation instead it is only necessary to use such small amounts of solvents that it is no longer necessary to remove them from the dispersions. Moreover, the novel aqueous dispersions ought also to be able to be prepared on the basis of polyurethane-free alkyd resins. In the preparation of the novel aqueous dispersions, furthermore, it ought to be possible to modify the alkyd resins with olefinically unsaturated monomers which do contain reactive functional groups in addition to the olefinically unsaturated double bond. Over and above this, the novel aqueous dispersions ought to give coating materials, adhesives, and sealing compounds which can be employed broadly and which give coatings, adhesive films, and seals that are of particularly high quality and long service life.
Found accordingly has been the novel aqueous dispersion of an acrylate-modified alkyd resin which is preparable in the presence of at least one water-miscible diol by
(1) dispersing in water at least one alkyd resin containing based on its total amount from 0.1 to 10% by weight of pendant and/or terminal allyloxy groups to give the dispersion 1,
(2) subjecting a mixture of methacrylic acid and at least one further, carboxyl-free olefinically unsaturated monomer to graft copolymerization in the dispersion 1 to give the dispersion 2, and
(3) once or n times subjecting
(3.1) at least one olefinically unsaturated monomer which is free from acid groups and/or
(3.2) at least one mixture of at least one olefinically unsaturated monomer which contains acid groups and at least one olefinically unsaturated monomer which is free from acid groups
to graft copolymerization in the dispersion 2 or 2 to n−1 resulting from the respective preceding step (2) or (2) to (n−1) of the process, with the proviso that in step (3) of the process or its repetitions (3) to (n) acid groups are incorporated in an amount which corresponds in total to not more than 90 mol % of the amount of acid groups incorporated in step (2) of the process.
The novel aqueous dispersion of an acrylate-modified alkyd resin is referred to below as dispersion of the invention,
further subject matter of the invention will emerge from the description.
In the light of the prior art it was surprising and unforeseeable for the skilled worker that the dispersions of the invention, even with particle sizes of up to 1 &mgr;m, were stable and free from gel specks, despite being substantially free from organic solvents. It was further surprising that for their preparation it was possible to do largely without organic solvents requiring removal from the dispersion afterward. Another surprise was the extremely broad applicability of the dispersion of the invention, which goes well beyond the technological fields in which acrylate-modified alkyd resins and their dispersions are commonly used.
The dispersion of the invention has a high solids content. Said content is preferably from 10 to 80%, more preferably from 15 to 70%, with particular preference from 20 to 65%, with very particular preference from 30 to 60%, and in particular from 40 to 55% by weight, based on the total amount of the dispersion of the invention.
The essential constituent of the dispersion of the invention is the acrylate-modified alkyd resin. Its molecular weight may vary very widely and is guided primarily by the respective intended use of the dispersion of the invention. Its number-average molecular weight is preferably from 2 000 to 100 000, in particular from 2 000 to 50 000. It is also possible for the acid number and the hydroxyl number to vary widely. The acid number is preferably from 20 to 70, in particular from 30 to 40, mg KOH/g and the hydroxyl number is preferably from 10 to 150, in particular from 30 to 90, mg KOH/g. The glass transition temperature may likewise vary very widely. In accordance with the invention, however, it is of advantage if it lies above 0° C. It is preferably from 1 to 80° C., in particular from 2 to 60° C.
The preparation of the acrylate-modified alkyd resin for inventive use starts from an alkyd resin which preferably has a number-average molecular weight of from 1 000 to 3 000 and in particular from 1 000 to 2 000. The acid number is preferably from 15 to 40, in particular from 30 to 35, mg KOH/g. The hydroxyl number is preferably from 30 to 150, in particular from 40 to 60, mg KOH/g. The iodine number according to DIN 53241-1 is from 0 to 200 g, in particular from 50 to 200 g, of iodine/100 g. The glass transition temperature of the alkyd resin is preferably below 0° C., in particular from −70 to −10° C. The oil content of the alkyd resins may likewise vary very widely and is guided in particular by the requirements of the respective intended use. It is preferred to employ a fatty acid content or an oil content of from 20 to 80% by weight and in particular
Kadambande Vijay
Rink Heinz-Peter
Asinovsky Olga
BASF Coatings AG
Seidleck James J.
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