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
2001-06-26
2004-06-15
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...
C428S423100, C524S589000, C524S590000, C524S839000, C524S840000, C528S044000, C528S060000, C528S080000, C528S081000, C528S083000, C528S084000, C528S085000
Reexamination Certificate
active
06750286
ABSTRACT:
The present invention relates to a novel polyurethane and to a novel polyurethane dispersion and to the use thereof in the aqueous finishing of plastics. The present invention additionally relates to a novel aqueous coating material which comprises the novel polyurethane and the novel polyurethane dispersion. The present invention further relates to a novel process for producing multicoat finishes on plastics. The present invention relates not least to novel finishes, including multicoat finishes, for plastics, and to plastics components which have these novel finishes.
Polyurethanes, their aqueous dispersions, aqueous coating materials based on polyurethanes, the use of these aqueous coating materials as waterborne basecoat materials for producing multicoat finishes, by the wet-on-wet technique, for example, and also the finishes themselves are known 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 and EP-A-0 401 565.
In automotive OEM finishing, these known aqueous coating materials and processes are outstandingly suitable for the wet-on-wet finishing of metal components coated beforehand with electrocoat materials and primer-surfacers or primers. In the wet-on-wet technique, as is known, the waterborne basecoat material is applied but then is not cured but instead is merely dried. The clearcoat material, in solution in organic solvents, is applied to the waterborne basecoat film, after which the two films are baked together.
Aqueous coating materials for the finishing of plastics are likewise known. They utilize the polyurethane dispersions of the known waterborne basecoat materials, which are described, inter alia, in the patents mentioned above. The plastics finishes in question, however, exhibit considerable weaknesses in moisture resistance. This becomes particularly evident in the condensation test and in the course of steam jet testing. These weaknesses are manifested in a particularly disadvantageous fashion on modern automobile bodies, where finished plastics components and metal components adjoin one another, since it is here that the difference in adhesion is especially pronounced.
It is an object of the present invention to provide a novel polyurethane and a novel polyurethane dispersion which no longer have the disadvantages of the prior art but which instead permit the preparation of aqueous coating materials which can be used for aqueous plastics finishing and provide single-coat or multicoat plastics finishes having outstanding optical properties and outstanding adhesion even following condensation exposure. Moreover, the novel aqueous coating materials should also be easy to apply by the wet-on-wet technique.
The invention accordingly provides the novel polyurethane which has a number average molecular weight Mn of from 3,000 to 50,000 and an acid number of from 10 to 35 and is preparable by reacting
(a1) at least one polyesterpolyol having a number average molecular weight Mn of from 1,000 to 4,000, preferably from 1,200 to 3,000, an acid number of from 0 to 15, preferably from 0 to 10, and an OH number of from 35 to 150, preferably from 50 to 120, based on acyclic aliphatic and cycloaliphatic dicarboxylic acids,
(a2) a mixture of at least one diol and one triol,
(a3) at least one compound containing at least two isocyanate-reactive functional groups (a31) and at east one functional group (a32) capable of forming anions, an
(a4) a mixture of at least one acyclic aliphatic and at least one cycloaliphatic diisocyanate,
with the proviso that
(i) in the mixture (a2) the diols and triols are in a molar ratio of from 2:1 to 13:1, preferably from 2.5:1 to 8:1,
(ii) the molar ratio of the polyesterpolyols (a1) to the mixture (a2) is from 4.5:1 to 1:1, preferably from 3.5:1 to 1.5:1, and
(iii) in the mixture (a4) the acyclic aliphatic and cycloaliphatic diisocyanates are in a molar ratio of from 1:0.16 to 1:6, preferably from 1:0.5 to 1:5.5;
to give an isocyanato-containing prepolymer which is then chain extended with a polyfunctional amine or amino alcohol and, if desired, is neutralized.
In the text below, the novel polyurethane is referred to, for the sake of clarity, as the “polyurethane of the invention”.
The invention additionally provides the novel polyurethane dispersion which comprises at least one polyurethane (A) of the invention dispersed in an aqueous medium (B).
In the text below, the novel polyurethane dispersion is referred to, for the sake of clarity, as the “polyurethane dispersion of the invention”.
The invention also provides the novel aqueous coating materials which comprise at least one polyurethane (A) of the invention or one polyurethane dispersion (A/B) of the invention.
In the text below, the novel aqueous coating materials are referred to, for the sake of clarity, as “coating materials of the invention”.
The invention also provides a novel process for coating plastics with a multicoat finish by
(I) applying a two component waterbased primer and curing it to give a primer coat,
(II) applying an aqueous coating material to the primer coat,
(III) applying a two component clearcoat material wet on wet, and
(IV) curing the resultant basecoat/clearcoat film,
using an aqueous coating material comprising
(A) at least one polyurethane preparable by reacting
(a1) a polyesterpolyol based on acyclic aliphatic and cycloaliphatic dicarboxylic acids,
(a2) a mixture of at least one diol and at least one triol,
(a3) at least one compound containing at least two isocyanate-reactive functional groups (a31) and at least one functional group (a32) capable of forming anions, and
(a4) a mixture of at least one acyclic aliphatic and at least one cycloaliphatic diisocyanate
to give an isocyanato-containing prepolymer which is then chain extended with a polyfunctional amine or amino alcohol and, if desired, is neutralized.
In the text below, the novel process for coating plastics with a multicoat finish is referred to, for the sake of brevity, as the “process of the invention”.
The invention additionally provides the novel plastics finishes producible by means of the coating materials of the invention and/or with the aid of the process of is the invention.
In the text below, the novel plastics finishes are referred to, for the sake of clarity, as the “plastics finishes of the invention”.
The invention provides not least the novel plastics components which carry the plastics finishes of the invention and which are referred to below as “plastics components of the invention”.
The polyurethane of the invention has a number average molecular weight Mn of from 3,000 to 50,000 and an acid number of from 10 to 35. It may be prepared by reacting the inventively suitable components described below with one another in the manner described below.
The first important component for preparing the polyurethane of the invention is at least one polyesterpolyol (a1) having a number average molecular weight Mn of from 1,000 to 4,000, preferably from 1,200 to 3,000, an acid number of from 0 to 15, preferably from 0 to 10, and an OH number of from 35 to 150, preferably from 50 to 120, based on acyclic aliphatic and cycloaliphatic dicarboxylic acids.
Examples of suitable acyclic aliphatic dicarboxylic acids for use in accordance with the invention are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid or dodecanedicarboxylic acid, of which adipic acid, glutaric acid, azelaic acid and/or sebacic acid are advantageous and are therefore used with preference.
Examples of
Hartung Michael
Schwarte Stephan
BASF Coatings AG
Niland Patrick D.
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