Stock material or miscellaneous articles – Vehicle body ornament
Reexamination Certificate
2001-10-04
2003-10-07
Zacharia, Ramsey (Department: 1773)
Stock material or miscellaneous articles
Vehicle body ornament
C428S411100, C428S423100, C428S522000, C427S379000, C427S385500, C427S407100, C525S330500, C525S374000, C525S379000, C525S384000, C525S458000
Reexamination Certificate
active
06630211
ABSTRACT:
The present invention relates to the novel use of tricyclodecanedimethanol both to produce and as an adhesion promoter in multicoat systems, especially multicoat clearcoats. The present invention also relates to a novel coating material, in particular a novel clearcoat material, which comprises tricyclodecanedimethanol. The present invention further relates to a novel method of improving the intercoat adhesion in multicoat clearcoats. Moreover, the invention relates to a novel multicoat system comprising a multicoat clearcoat. Furthermore, the present invention relates to a new process for producing multicoat systems which is based on the wet-on-wet technique. The present invention relates not least to the use of the novel multicoat systems especially in automotive OEM finishing, automotive refinish, and industrial coating, including container coating and coil coating.
The requirements imposed on the resistance of topcoats which are exposed to weathering, especially insolation and acid rain, and also, even more frequently, to mechanical stress, especially that produced by wash-brush cleaning installations, are becoming increasingly more stringent. This applies most particularly to vehicle finishes, which have to meet these requirements while also satisfying very high optical demands regarding gloss, surface smoothness, and color.
To date this problem has been solved by applying to the substrates a multicoat system which, in accordance with the heightened environmental compatibility requirements, is composed substantially of aqueous coating materials. In the case of metal substrates, this coating system is conventionally produced from an aqueous electrocoat material, a water-based primer-surfacer, an aqueous basecoat material, and a solventborne clearcoat material. The electrocoat material and the water-based primer-surfacer are each baked following their application, and then constitute the primer. The aqueous basecoat material is applied atop said primer and subjected to interim drying. Over this film, which is not yet fully cured, the clearcoat material is applied, after which the two films are cured together (wet-on-wet technique). Where the substrates used comprise plastics, water-based primers are conventionally employed in place of the electrocoat material.
The wet-on-wet technique for producing multicoat topcoats is described, for example, in the patents
US-A-3,639,147,
DE-A-33 33 072,
DE-A-38 14 853,
GB-A-2 012 191,
US-A-3,953,644,
EP-A-0 260 447,
DE-A-39 03 804,
EP-A-0 320 552,
DE-A-36 28 124,
US-A-4,719,132,
EP-A-0 297 576,
EP-A-0 069 936,
EP-A-0 089 497,
EP-A-0 195 931,
EP-A-0 228 003,
EP-A-0 038 127 and
DE-A-28 18 100.
The optical or visual appearance and the weathering stability are primarily the responsibility of the two topmost coats of the multicoat systems. Thus the aqueous basecoat gives the multicoat system its color and/or optical effects such as metallic effects or interference effects, while the clearcoat provides not only scratch and etch resistance, i.e., resistance to damaging environmental substances, but also provides the appearance qualities, i.e., the gloss, brilliance, and evenness. In this system, aqueous basecoat material and clearcoat material must be very precisely matched to one another in order to produce a system having the desired advantageous profile of properties.
Aqueous basecoat materials and the corresponding coating systems which substantially meet these requirements 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.
These aqueous basecoat materials comprise, in particular, anionically stabilized polyurethanes, with neutralizing agents used including polyfunctional amines and/or amino alcohols, such as triethylamine, methylethanolamine and/or dimethylethanolamine.
In modern automotive OEM finishing and refinishing, use is nowadays made of numerous different clearcoat materials, such as the solventborne one-component (1K), two-component (2K) or multicomponent (3K, 4K) clearcoat materials, the aqueous two-component (2K) or multicomponent (3K, 4K) clearcoat materials, the powder clearcoat materials, the powder slurry clearcoat materials, or the UV clearcoat materials, especially those free from solvent or in powder form. All of these clearcoat materials have quite specific advantages which it is desired to utilize specifically for the respective intended use.
For example, one-component (1K) clearcoat materials produce multicoat systems which satisfy very stringent optical requirements and are resistant to abrasion, although the clearcoats in question are often not sufficiently stable to weathering. In contrast, the clearcoats based on two-component (2K) or multicomponent (3K, 4K) clearcoat materials, although very stable to weathering, often lack sufficient abrasion resistance.
It would therefore be desirable in principle, in a multicoat system, to combine the specific advantages of materially different clearcoats with one another in order to obtain multicoat clearcoats which, for example, are both weathering-stable and abrasion-resistant. This should be achieved, moreover, without additional effort for the user.
However, this is not easily achieved, since the combination of the known clearcoat materials to give multicoat clearcoats is accompanied by serious problems of intercoat adhesion. These problems may result in delamination not only of the topmost clearcoat but also of the one beneath it. These problems are particularly evident in automotive refinish, where, indeed, the refinish clearcoat must form a firmly adhering bond with the clearcoat of the automotive OEM coating system. To date it has been possible to solve this problem of intercoat adhesion only by sanding the clearcoat to be refinished. This operation, however, constitutes an additional work step in the coating operation, which is fundamentally disadvantageous.
It is an object of the present invention to provide a novel multicoat system which no longer has the disadvantages of the prior art but which instead not only has an outstanding profile of optical properties, or an outstanding appearance, but also possesses a high level of hardness, scratch resistance and etch resistance, with surface defects and delaminations no longer occurring. A further object of the present invention was to provide a novel process for producing multicoat systems which produces the novel multicoat systems simply, safely, and reliably.
The invention accordingly provides the novel coating material, in particular the novel clearcoat material, which comprises at least one binder, at least one crosslinking agent, and tricyclodecanedimethanol.
In the text below, the novel coating material is referred to as the “coating material of the invention”.
The invention also provides the novel multicoat system on a primed or unprimed substrate, comprising
(A) a basecoat,
(B) a first clearcoat as intermediate coat, and
(c) a second clearcoat as topmost coat,
wherein at least one of the coating materials (B) and (C) employed to produce the clearcoats (B) and (C) comprises tricyclodecanedimethanol in effective amounts.
In the text below, the novel, highly scratch-resistant multicoat system is referred to as the “multicoat system of the invention”.
The invention further provides the novel process for producing a multicoat system, said process comprising at least the following steps:
(I) applying a basecoat material (A) to a primed or unprimed substrate,
(II) drying the applied basecoat material (A),
(III) applying a first clearcoat material (B),
(IV) curing togeth
Baumgart Hubert
Farwick Thomas
Rink Heinz-Peter
Röckrath Ulrike
BASF Coatings AG
Zacharia Ramsey
LandOfFree
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