Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
1999-04-01
2001-06-05
Berman, Susan W. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S423100, C522S096000, C522S173000, C522S174000
Reexamination Certificate
active
06242101
ABSTRACT:
RADIATION-CURABLE FORMULATIONS
The present invention relates to radiation-curable formulations which comprise at least one prepolymer having at least two olefinic double bonds per molecule and at least one difunctional ester of &agr;,&bgr;-ethylenically unsaturated carboxylic acids with diols having a linear alkylene chain which has 7 to 14 carbon atoms.
Radiation-curable compositions have acquired widespread importance in the art, especially as high-grade surface coating materials. By radiation-curable compositions are meant formulations which include ethylenically unsaturated polymers or prepolymers and which, directly or after a physical drying step, are cured by exposure to high-energy radiation; for example, by irradiation with UV light or by irradiation with high-energy electrons (electron beams).
Particularly high-grade coatings are obtained on the basis of polyfunctional &agr;,&bgr;-ethylenically unsaturated polymers or prepolymers. Such ethylenically unsaturated prepolymers are known from P. K. T. Oldring (ed.), Chemistry and Technology of UV- and EB-Formulations for Coatings, Inks and Paints, Vol. II, SITA Technology, London 1991, on the basis, for example, of epoxy acrylates (pp. 31-68), urethane acrylates (pp. 73-123) and melamine acrylates (pp. 208-214).
Ethylenically unsaturated compounds of low molecular mass are often added to such compositions in order to reduce their viscosity. Like the ethylenically unsaturated polymers and prepolymers, said compounds are polymerized in the course of curing and so are incorporated into the coating. They are therefore referred to as reactive diluents. The properties of the resulting coatings are therefore determined both by the ethylenically unsaturated polymer or prepolymer employed and by the reactive diluent. Furthermore, for optimum coating properties, it is necessary to harmonize the ethylenically unsaturated polymers or prepolymers with the reactive diluents.
Because of their advantageous processing properties, radiation-curable formulations have become established for the coating of wood, paper and plastics in the interior applications segment. Exterior application, on the other hand, is still tied up with problems because of the high caliber of requirements it imposes on the weathering stability of such radiation-curable formulations.
The prior art discloses a large number of radiation-curable formulations which comprise, as monomers, oligomers or reactive diluents, multifunctional acrylates based on diols or polyols. For instance, GB-B-1 138 117 describes radiation-curable coating materials based on unsaturated polyester resins, with styrene and methyl methacrylate as reactive diluent. JP 62 110 779 and JP 62 132 568 likewise disclose radiation-curable coating materials, based on urethane oligomers and trifunctional reactive diluents. A series of further patents describes the use of such radiation-curable formulations for optical applications, examples being U.S. Pat. No. 5,250,391 for holograms, EP-A-324 480 for refractive index imaging and JP 62 047 842 for optical disks. These formulations, however, are not intended for exterior applications, or comprise radiation-curable prepolymers or resins of high molecular mass.
The use of 1,6-hexanediol diacrylate as a reactive diluent is known from WO 92/17337 and DE 25 37 783 A. In formulations, it produces good gloss stability under weathering conditions (N. Round et al., Radiation Curing Conference Proceedings (1986)), and yet Radiat. Curing (1984), 11 (3), 24-30, 32/3 describes how the physical properties of hydrocarbon-based diol diacrylates are poorer than those of glycol ether-based diol diacrylates, especially as regards hardness and abrasion characteristics. In addition, radiation-curable formulations based on aliphatic urethane acrylates and 1,6-hexanediol diacrylate show signs of incompatibility with substrates, for example, comprising plastics such as PMMA, polycarbonate and acrylonitrile-styrene polymers, said incompatibility being manifested in incipient dissolution of the substrate and an associated deterioration in the properties.
A fundamental problem with the prior art radiation-curable compositions is that, although individual application properties such as coating hardness, flexibility and weathering stability can be improved by selecting and harmonizing the components (prepolymer and reactive diluent), this is always at the expense of other application properties. It is an object of the present invention, therefore, to provide radiation-curable compositions which, without the addition of inert organic solvents, combine good processing properties with good properties of the coating. In particular, it is intended that the formation should have good reactivity and high substrate compatibility in conjunction with good mechanical strength and high weathering stability and chemical resistance.
We have found that this object can, surprisingly, be achieved by a radiation-curable formulation which comprises at least one prepolymer having at least two olefinic double bonds per molecule and at least one difunctional ester of &agr;,&bgr;-ethylenically unsaturated carboxylic acids with diols having a linear alkylene chain which has 7 to 14 carbon atoms.
The present invention therefore provides radiation-curable formulations which comprise
i) at least one prepolymer which comprises at least two olefinic double bonds per molecule (component A), and
ii) at least one diester of &agr;,&bgr;-ethylenically unsaturated carboxylic acid with diols having a linear alkylene chain which has 7 to 14 carbon atoms (component B).
In general, the compositions of the invention contain from 20 to 90% by weight, preferably from 30 to 80% by weight and, in particular, from 40 to 70% by weight of component A, from 10 to 80% by weight, preferably from 20 to 60% by weight and, in particular, from 30 to 50% by weight of component B, and up to 20% by weight, based on the overall weight of components A and B, of customary additives.
In general, component A is composed of one or more structural elements which function as carriers for the structural units comprising olefinic double bonds. Suitable structural elements include aliphatic urethanes based on diisocyanates and suitable monools, diols and polyols, dimers and trimers of diisocyanates, melamine-formaldehyde adducts, polyetherpolyols, cooligomers of unsubstituted or substituted vinylaromatic compounds with &agr;,&bgr;-ethylenically unsaturated carboxylic acids and/or their derivatives, and other groups suitable for synthesizing a prepolymer.
A prepolymer (component A) having at least two unsaturated double bonds is obtained by combining the abovementioned structural elements with suitable structural units carrying &agr;,&bgr;-ethylenically unsaturated double bonds. Such structural units include, in particular, vinyl- or allyl-functional hydroxyalkanes, vinyl or allyl esters of aliphtic, functionalized carboxylic acids, and esters of &agr;,&bgr;-ethylenically unsaturated carboxylic acids with diols and polyols.
Accordingly, examples of suitable prepolymers (components A) are urethane oligomers, preferably aliphatic urethane oligomers having at least two olefinic double bonds, with aliphatic structural elements comprising not only alkylene groups, preferably those having 4 to 10 carbon atoms, but also cycloalkylene groups having preferably 6 to 20 carbon atoms, it being possible for both the alkylene and the cycloalkylene units to be substituted one or more times by C
l
-C
4
-alkyl, especially methyl, or to include one or more nonadjacent oxygen atoms.
Such prepolymers with urethane and/or urea groups that are suitable as components A are obtainable by reacting di-, tri- and polyfunctional isocyanate compounds with &agr;,&bgr;-ethylenically unsaturated compounds which in addition have at least one isocyanate-reactive group, examples being OH groups or NH groups.
The difunctional isocyanate compounds are usually selected from aliphatic, aromatic and cycloaliphatic diisocyanates. In general, they have 4 to 22 carbon atoms. In particular, the
Beck Erich
Enenkel Peter
Koniger Rainer
Menzel Klaus
Paulus Wolfgang
BASF - Aktiengesellschaft
Berman Susan W.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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