Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-11-16
2004-04-06
Berman, Susan (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S104000, C522S127000, C522S129000, C522S134000, C522S146000, C522S170000, C522S172000, C522S173000, C522S174000, C522S175000, C522S179000, C522S180000, C522S181000, C522S178000, C522S168000, C522S182000, C522S183000, C528S029000, C528S075000, C528S085000, C528S205000, C528S376000, C528S418000, C528S425000, C428S423100, C428S413000, C428S419000, C428S482000, C428S500000
Reexamination Certificate
active
06716891
ABSTRACT:
The present invention relates to a novel coating material curable thermally and with actinic radiation. The present invention also relates to the use of the novel coating material for producing novel clearcoats and multicoat color and/or effect coating systems for automotive OEM finishing and refinish, industrial coating, including coil coating and container coating, the coating of plastics, and furniture coating.
Automobile bodies, plastic parts for automobiles or domestic appliances and industrial components are nowadays protected by a clearcoat. The clearcoat may be the only coating film used, or else may form the uppermost coat of a multicoat topcoat system.
Automobile bodies in particular are provided extensively with a multicoat topcoat system. Clearcoats are frequently applied as the final coat. Materials suitable for this purpose are the customary and known one-component (1K), two-component (2K), multicomponent (3K, 4K), powder clearcoat or powder slurry clearcoat materials, or UV-curable clearcoat materials.
One-component (1K), two-component (2K) or multicomponent (3K, 4K) clearcoat materials are described, for example, in the patents U.S. Pat. No. 5,474,811, U.S. Pat. No. 5,356,669, U.S. Pat. No. 5,605,965, WO 94/10211, WO 94/10212, WO 94/10213, EP 0 594 068 A1, EP 0 594 071 A1, EP 0 594 142 A1, EP 0 604 992 A1, WO 94/22969, EP 0 596 460 A1, and WO 92/22615.
Powder clearcoat materials are known, for example, from the German patent DE 42 22 294 A1 or from the BASF Lacke+Farben AG product information bulletin “Pulverlacke” [Powder coating materials], 1990.
A powder coating material which is curable thermally and with actinic radiation is known from the European patent EP 0 844 286 A1. It comprises an unsaturated binder and a second resin, copolymerizable with the first, and also a photoinitiator and a thermal initiator, and accordingly is curable thermally and with actinic radiation. However, this dual-cure powder coating material is used as a pigmented topcoat material, which is cured superficially with UV light and thermally in the regions close to the substrate. The patent does not reveal whether this known powder coating material is also suitable for producing clearcoats, especially in multicoat systems.
Powder slurry coating materials comprise powder coating materials in the form of aqueous dispersions. Slurries of this kind are described, for example, in the U.S. patent U.S. Pat. No. 4,268,542 and in the German patent applications DE 195 18 392.4 A1 and DE 196 13 547 A1, and in the German patent application DE 198 14 471.7 A1, which was unpublished at the priority date of the present specification.
UV-curable clearcoat materials are disclosed, for example, by the patents EP 0 540 884 A1, EP 0 568 967 A1 or U.S. Pat. No. 4,675,234 A1.
Each of these clearcoat materials has specific strengths and weaknesses. Using these clearcoat materials, multicoat systems are obtained which satisfy the optical requirements. However, the scratch-resistant one-component (1K) clearcoat materials are sometimes not sufficiently weather-resistant, whereas the weather-resistant two-component (2K) or multicomponent (3K, 4K) clearcoat materials are often not sufficiently scratch-resistant. Certain one-component (1K) clearcoat materials are indeed scratch-resistant and weather-stable but, in combination with frequently employed waterborne basecoat materials, exhibit surface defects such as shrinkage (wrinkling).
Powder clearcoat materials, powder slurry clearcoat materials, and UV-curabled clearcoat materials, on the other hand, exhibit a not entirely satisfactory intercoat adhesion, without offering a complete solution to the problems of scratch resistance or etch resistance. In particular, the severe polymerization shrinkage of the UV-curable clearcoat materials gives them a particular tendency towards delamination.
EP 0 568 967 A1 discloses a process for producing multicoat systems in which a thermally curable clearcoat film is applied by the wet-on-wet technique to a pigmented basecoat film, after which the two films are heat-cured together. Atop of the cured clearcoat there is subsequently applied at least one further clearcoat film, based on coating materials curable with actinic radiation, and curing is carried out with actinic radiation, or thermally and with actinic radiation. This process gives clearcoats of high chemical resistance and optical quality. However, the scratch resistance is not satisfactory.
Furthermore, EP 0 568 967 A1 discloses a process in which a coating material curable with actinic radiation is applied to the pigmented basecoat film and cured. Subsequently, a further coat of the same coating material is applied and is cured with actinic radiation. Although this results in a highly glossy surface without perceptible texture, the clearcoat in question yellows. Additionally, the scratch resistance still leaves something to be desired.
It is an object of the present invention to provide a novel coating material which no longer has the disadvantages of the prior art but which instead provides, simply, novel clearcoats and color and/or effect coating systems which exhibit no elimination of constituents on baking and which are scratch-resistant, stable to weather, free from yellowing, hard, flexible, and free from surface defects, which exhibit a high level of adhesion on all substrates, and which may be produced in the high coat thickness needed for an outstanding overall appearance.
The invention accordingly relates to a novel coating material curable thermally and with actinic radiation, comprising
(a1) at least one constituent containing
(a11) at least two functional groups which serve for crosslinking with actinic radiation, and
(a12) at least one functional group which is able to undergo thermal crosslinking reactions with the hydroxyl and/or thiol groups (a21) in the constituent (a2), and
(a2) at least one branched, cyclic and/or acyclic C
9
-C
16
alkane functionalized with at least two hydroxyl or thiol groups or with at least one hydroxyl and at least one thiol group (a21).
In the text below, the novel coating material curable thermally and with actinic radiation is referred to as the “coating material of the invention”.
In the text below, the branched, cyclic and/or acyclic C
9
-C
16
alkanes (a2) for use in accordance with the invention that are functionalized with at least two hydroxyl or thiol groups or with at least one hydroxyl and at least one thiol group are referred to for short as “functionalized alkanes (a2)”.
The invention further provides the novel clearcoats and multicoat color and/or effect coating systems which can be produced with the aid of the coating material of the invention.
In the text below, the novel clearcoats and multicoat color and/or effect coating systems are referred to as “clearcoat of the invention” and “multicoat systems of the invention”, and the corresponding processes for producing them are referred to as “coating processes of the invention”.
In the context of the present invention, the term “thermal curing” denotes the heat-initiated curing of a film of a coating material, in the context of which normally a separate crosslinking agent is employed. This is customarily referred to by those in the art as external crosslinking. Where the crosslinking agents are built into the binders, the term self-crosslinking is 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 normally initiated by free-radical or cationic photoinitiators and in terms of its mechanism is a free-radical or cationic photopolymerization.
Where thermal curing and curing with actinic light are employed together for a coating material, the term “dual cure” is also used.
In the light of the prior art it was surprising and unforeseeable for the skilled worker that the object on which the invention is based might be achieved with the aid of the
Baumgart Hubert
Joost Karl-Heinz
Meisenburg Uwe
Rink Heinz-Peter
BASF Coatings AG
Berman Susan
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