Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2002-12-11
2004-10-12
Seidleck, James J. (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, C522S093000, C522S096000, C522S106000, C522S109000, C522S110000, C522S111000, C522S120000, C522S134000, C522S135000, C522S139000, C522S144000, C522S165000, C522S174000, C522S035000, C522S902000, C523S500000
Reexamination Certificate
active
06803393
ABSTRACT:
The present invention relates to a novel multicomponent system curable thermally and with actinic radiation. The present invention further relates to a process for producing the novel multicomponent system curable thermally and with actinic radiation. The present invention additionally relates to the use of the novel multicomponent system curable thermally and with actinic radiation for priming plastics parts.
The coating of plastics parts is becoming increasingly important, especially in the motor vehicle industry. Here, a segment showing particularly rapid growth is that of mounted plastics components. However, the coating of plastics still causes great problems, brought about in particular by the variable surface smoothness of the plastics parts, the adhesion of coatings to different plastics surfaces, and the formation of gas bubbles and holes in the coatings on curing.
In order to solve these problems, it is common to apply special primers intended to compensate the unevennesses of the plastics surfaces and ensure that the coatings adhere to the plastics surfaces. For this purpose it is common to use what are known as multicomponent systems, where owing to its high reactivity the crosslinker component is stored separately from the binder component prior to application. Examples of such multicomponent systems are those are known as polyurethane systems, where the binding component comprises isocyanate-reactive functional groups and the crosslinker component comprises polyisocyanates.
The disadvantage of these multicomponent systems is their comparatively long reaction time, unacceptable especially in OEM automotive finishing. Although the reaction time could be shortened by applying heat, to do so would reintroduce the problem of formation of bubbles. The surface defects caused by the gas bubbles in the primers would then have to be made good by sanding, which is laborious and expensive.
Multicomponent systems curable thermally and with actinic radiation, and their use as coating materials, are known, for example, from European Patent Application EP 0 928 800 A1. The known coating materials comprise a urethane (meth)acrylate, containing (meth)acrylate groups and free isocyanate groups, a UV initiator which initiates free-radical polymerization (photoinitiator), and an isocyanate-reactive compound. Suitable isocyanate-reactive compounds include polyols such as polyesters formed from diols and triols with dicarboxylic acids, hindered amines formed from maleic esters and cycloaliphatic primary diamines, polyether polyols, or hydroxyl-containing (meth)acrylate copolymers. The priming of plastics parts is not addressed in the European Patent Application.
German Patent Application DE 199 20 799, unpublished at the priority date of the present specification, describes a multicomponent system curable thermally and with actinic radiation. As its binder component it comprises a hydroxyl-free polyurethane having pendant acrylate groups, and a polyester polyol, and as its crosslinking component, a polyisocyanate containing acrylate groups. The multicomponent system is used to seal sheet molded compounds (SMC) and bulk molded compounds (BMC). There is no use, however, of any crosslinker components or binder components which include dicyclopentadienyl groups and/or endomethylenetetrahydrophthalic acid groups.
German Patent Application DE 199 03 725, unpublished at the priority date of the present specification, describes a coating material comprising an essentially hydroxyl-free, unsaturated polyester having dicyclopentadienyl groups and/or endomethylenetetrahydrophthalic acid groups and a hydroxyl-free polymer, materially different from the polyester, which may include the aforementioned groups. It is mentioned in passing in the application that the coating material may be cocrosslinked with polyisocyanates. Details of how this is to be done are not given. Moreover, the known coating material is said to be used in particular as a powder coating material.
It is an object of the present invention to find a new multicomponent system, curable thermally and with actinic radiation, from which the disadvantages of the prior art are now absent and which instead is easy to apply, leads rapidly and reliably at comparatively low temperatures to coatings, especially primer coats on plastics parts, which are free from surface defects such as bubbles and cracks, provide outstanding compensation of unevennesses in plastics surfaces, and exhibit excellent adhesion to the plastics surfaces and to coatings applied to the primer coats.
We have found that this object is achieved by the novel multicomponent system, curable thermally and with actinic radiation, which comprises the following components:
A) an isocyanate-reactive binder component comprising
A1) at least one unsaturated polyester whose molecule contains on average at least one group that can be activated with actinic radiation, of the formulae I, II and/or III
and
A2) at least one binder, different than the polyester (A1), whose molecule comprises on average at least two isocyanate-reactive functional groups, and/or
A3) at least one binder, different than the polyester (A1), whose molecule comprises on average at least one isocyanate-reactive functional group and at least one reactive functional group having at least one bond that can be activated with actinic radiation, and
B) a crosslinker component comprising
B1) at least one polyisocyanate and/or
B2) at least one polyisocyanate whose molecule comprises on average at least one reactive functional group having at least one bond that can be activated with actinic radiation.
In the text below, the novel multicomponent system curable thermally and with actinic radiation is referred to as the “multicomponent system 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 by the skilled worker that the object on which the present invention is based might be achieved with the aid of the multicomponent system of the invention. A particular surprise was that the multicomponent system of the invention, following its preparation, i.e., after the mixing of its components, had a processing time or pot life which is long for multicomponent systems, and nevertheless, following application, cured rapidly at comparatively low temperatures without any risk of bubbles being formed.
In the context of the present invention, actinic radiation is electromagnetic radiation such as near infrared (NIR), visible light or UV light or corpuscular radiation such as electron beams.
Curing with heat and actinic radiation is referred to below using the term commonly employed in the art, namely “dual cure”.
At the time of application, the multicomponent system of the invention may be present in a variety of physical forms. For instance, it may be in the form of an aqueous solution or dispersion, an organic solution or dispersion, an essentially water- and solvent-free, liquid 100% system, an essentially water- and solvent-free, finely divided, solid powder coating material, or a powder coating dispersion (powder slurry). It is of advantage in accordance with the invention if the multicomponent system of the invention is in the form of a liquid 100% system.
The first essential constituent of the multicomponent system of the invention is at least one isocyanate-reactive binder component (A) which comprises at least one unsaturated polyester (A1) and at least one binder (A2) and/or (A3) different than the polyester (A1).
In the context of the present invention, the term binder refers to oligomeric and polymeric resins, the oligomeric resins normally containing on average from 3 to 15 monomer units and the polymeric resins normally contain on average more than 10, in particular more than 15, monomer units per molecule.
The unsaturated polyester (A1) contains on average at least one, preferably at least two, group(s) of the formulae I, II and/or III that can be activated with actinic radiation. Preferably, the groups I a
Allard Maxime
Blum Rainer
BASF Coatings AG
McCledon Sanza L.
Seidleck James J.
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