Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-11-07
2003-06-24
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C427S372200, C427S385500, C524S591000, C524S507000, C524S839000, C524S840000, C525S123000, C525S124000, C525S127000, C525S455000
Reexamination Certificate
active
06583214
ABSTRACT:
The present invention relates to a novel aqueous coating material based on polyurethane, to its preparation and to its use in automotive OEM finishing and refinish, in industrial coating, including coil coating and container coating, in the coating of plastics, and in furniture coating.
Aqueous coating materials which cure physically without crosslinking agents and comprise at least one ionically and/or nonionically stabilized polyurethane based on bis(4-isocyanatocyclohexyl)methane with a trans/trans content of up to 18 mol %, based on the diisocyanate, in dispersion in an aqueous phase are known from the German patent DE-A-44 14 032. They have very good film-forming properties and provide clear, transparent coatings. In the patent it is also stated that these known coating materials may also comprise pigments.
Aqueous coating materials which are curable thermally and/or with actinic radiation and comprise an ionically and/or nonionically stabilized polyurethane which is saturated, unsaturated and/or grafted with olefinically unsaturated compounds and is based on bis(4-isocyanatocyclohexyl)methane with a trans/trans content of up to 18 mol %, based on the diisocyanate, and also a crosslinking agent are not disclosed in the patent.
Thermally curable aqueous coating materials which comprise a crosslinking agent and an ionically and/or nonionically stabilized polyurethane which is saturated, unsaturated and/or grafted with olefinically unsaturated compounds and is based on aliphatic, cycloaliphatic, aliphatic-cycloaliphatic, aromatic, aliphatic-aromatic, and/or cycloaliphatic-aromatic polyisocyanates, and the corresponding coatings, are known, for example, from the patents EP-A-0 089 497, EP-A-0 256 540, EP-A-0 260 447, EP-A-0 297 576, WO 96/12747, EP-A-0 523 610, EP-A-0 228 003, EP-A-0 397 806, EP-A-0 574 417, EP-A-0 531 510, EP-A-0 581 211, EP-A-0 708 788, EP-A-0 593 454, DE-A-43 28 092, EP-A-0 299 148, EP-A-0 394 737, EP-A-0 590 484, EP-A-0 234 362, EP-A-0 234 361, EP-A-0 543 817, WO 95/14721, EP-A-0 521 928, EP-A-0 522 420, EP-A-0 522 419, EP-A-0 649 865, EP-A-0 536 712, EP-A-0 596 460, EP-A-0 596 461, EP-A-0 584 818, EP-A-0 669 356, EP-A-0 634 431, EP-A-0 678 536, EP-A-0 354 261, EP-A-0 424 705, WO 97/49745, WO 97/49747 or EP-A-0 401 565. These known aqueous coating materials and the coatings produced with them already have very good performance properties. However, the finely dispersed polyurethanes commonly employed in these aqueous coating materials may for no discernible reason form coagulum which manifests itself unpleasantly in the coatings.
It is an object of the present invention to provide a novel coating material curable thermally and/or with actinic radiation which comprises at least one ionically and/or nonionically stabilized polyurethane, saturated, unsaturated and/or grafted with olefinically unsaturated compounds, in dispersion in an aqueous phase and which combines a profile of performance properties which matches or even exceeds that of the prior art with very little, if any, tendency to form coagulum.
The invention accordingly provides the novel aqueous coating material, curable thermally and/or with actinic radiation, which comprises
A) at least one ionically and/or nonionically stabilized polyurethane which is saturated, unsaturated and/or grafted with olefinically unsaturated compounds and is based on bis(4-isocyanatocyclohexyl)methane with a trans/trans content of up to 30% by weight, based on the diisocyanate, as binder and
B) at least one crosslinking agent.
In the text below, the novel aqueous coating material curable thermally and/or with actinic radiation is referred to as the “coating material of the invention”.
The invention also provides the novel process for producing a single-coat or multicoat clear or color and/or effect coating system by applying at least one film of the coating material of the invention to a primed or unprimed substrate and curing thermally and/or with actinic radiation the resultant wet film(s).
In the text below, this novel process is referred to as the “first process of the invention”.
The invention additionally provides the novel process for producing a multicoat color and/or effect coating system by the wet-on-wet technique, said process comprising at least the following steps:
(I) applying an aqueous basecoat film to a primed or unprimed substrate,
(II) flashing off and provisionally drying the resultant aqueous basecoat film,
(III) applying a clearcoat film to the aqueous basecoat film, and
(IV) curing the two wet films thermally and, if desired, with actinic light; and involving the use as aqueous basecoat material and/or as clearcoat material of at least one aqueous coating material which is
(i) physically curing and/or
(ii) which cures thermally and/or with actinic radiation,
said coating material comprising at least one ionically and/or nonionically stabilized polyurethane (A) which is saturated, unsaturated and/or grafted with olefinically unsaturated compounds and is based on bis(4-isocyanatocyclohexyl)methane with a trans/trans content of up to 30% by weight, based on the diisocyanate.
The invention additionally provides a variant of the second process of the invention, said process comprising at least the following steps:
(I) applying an aqueous basecoat film to a primed or unprimed substrate,
(II) flashing off and provisionally drying the resultant aqueous basecoat film,
(III) applying a first clearcoat film to the aqueous basecoat film,
(IV) curing the two wet films thermally and, if desired, with actinic light, and
(V) applying a second clearcoat film, materially different from the first clearcoat film, to the clearcoat film cured in process step (IV)
or alternatively
(I) applying an aqueous basecoat film to a primed or unprimed substrate,
(II) flashing off and provisionally drying the resultant aqueous basecoat film,
(III) applying a first clearcoat film to the aqueous basecoat film, and
(IV) flashing off and provisionally drying the resultant clearcoat film,
(V) applying a second, materially different, clearcoat film to the clearcoat film provisionally dried in process step (IV), and
(VI) conjointly curing the coating films (extended wet-on-wet technique);
and involving the use as aqueous basecoat material
and/or as at least one of the clearcoat materials of at least one aqueous coating material which is
(i) physically curing and/or
(ii) which cures the thermally and/or with actinic radiation,
said coating material comprising at least one ionically and/or nonionically stabilized polyurethane (A) which is saturated, unsaturated and/or grafted with olefinically unsaturated compounds and is based on bis(4-isocyanatocyclohexyl)methane with a trans/trans content of up to 30% by weight, based on the diisocyanate.
In the text below, the novel processes for producing a multilayer color and/or effect coating system by the wet-on-wet technique are referred to collectively as the “second process of the invention”.
In the context of the present invention, the term “physical curing” denotes the curing of a layer of a coating material by filming, possibly following drying of the layer. Normally, no crosslinking agents are necessary for this purpose. If desired, the physical curing may be assisted by atmospheric oxygen or by exposure to actinic radiation.
The coating material of the invention is curable thermally and/or with actinic radiation.
In the context of the present invention, the term “thermal curing” denotes the heat-initiated curing of a layer of coating material, normally employing a separate crosslinking agent. Customarily, this is referred by those in the art as external crosslinking. Where the crosslinking agents are already incorporated in the binders, the term self-crosslinking is also used. In accordance with the invention, external crosslinking is of advantage and is therefore employed with preference.
In the context of the present invention, actinic radiation means electron beams or, preferably, UV radiation. Curing by UV radiation is commonly initiated by means of free-radical or cationic photoin
Haeberle Karl
Lettmann Bernhard
Rink Heinz-Peter
BASF Coatings AG
Niland Patrick D.
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