Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1996-01-11
2002-11-05
Weiner, Laura (Department: 1745)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S107000, C522S179000, C430S285100, C430S908000, C428S480000, C428S481000, C428S482000, C427S487000
Reexamination Certificate
active
06476094
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to novel mixtures, curable under the action of UV radiation, containing unsaturated polyester resins and to the use thereof for the production of coatings on any desired substrates, in particular on wood or imitation wood.
2. Description of the Prior Art
Unsaturated polyester resins have long been known as binders for UV-curing coatings. DE-AS 1,694,149, for example, discloses that mixtures of unsaturated polyesters and polymerizable monomers may be cured by UV radiation with the addition of certain benzoin compounds. Due to the inhibitory action of atmospheric oxygen, lacquer coatings based on this system are often inadequately cured on the surface.
The addition of paraffins (“paraffin polyesters”), which accumulate on the surface during gelation, to avoid air inhibition in the case of conventional curing with peroxides is possible only to a certain extent because the thermal energy emitted by the UV light sources prevents the formation of the protective paraffin film. In these cases, a prior so-called pregelling zone must be provided.
Unsaturated polyesters which contain &agr;,&bgr;-unsaturated dicarboxylic acid residues and allyl ether and/or polyalkylene glycol residues (“gloss polyesters”) require no paraffin for curing the surface of the lacquer film because the ether groups initiate an autooxidative drying process. UV curing of such resins with allyl ether groups (DE-OS 2,113,998) or polyalkylene glycol residues (DE-OS 3,010,428) results, as does conventional curing, in readily sandable coatings, but the reactivity of such resins is often too low to ensure sufficiently high processing speeds.
EP-A 0,195,968 describes curable resin compositions based on one or more unsaturated polyesters which contain terminal dicyclopentenyl ester groups and are thus intended to exhibit extended storage stability. However, the claimed polyester resins are not suitable for curing under UV light.
EP-A- 0,284,888 describes unsaturated polyesters which, due to the incorporation of inter alia norbornene dicarboxylic acid residues, combine good levelling with rapid curing. However, this applies only at an application viscosity for curtain coating of>60 seconds (DIN 4 cup, 23° C.), which is achieved by dilution with styrene. Recently, however, there has been demand for binders which are equally rapidly curable at still greater dilution, i.e., at an application viscosity for curtain coating of<60 seconds, and in which the properties of the resulting coatings, such as hardness and scratch resistance, do not worsen. Lower viscosity is associated with advantages in deaeration and levelling of the lacquer films.
An object of the present invention is to provide unsaturated polyester resins which are suitable for the production of coating compositions which may be crosslinked under the action of UV radiation and cure rapidly with good levelling even when highly diluted with styrene and/or at a low application viscosity.
Surprisingly, this object may be achieved with the compositions according to the invention described hereinafter, which contain polyester resins as the primary component. Achieving the stated object is surprising because the desired more rapid curability even when highly diluted with styrene is not solely dependent upon the concentration of the olefinic double bonds incorporated in the polyester resins as would be expected, but may instead only be achieved if structural components a1) and a2) are simultaneously incorporated into the polyester resins in the quantities disclosed in greater detail below.
SUMMARY OF THE INVENTION
The present invention relates to compositions that may be cured under the action of UV radiation and contain
A) 40 to 80 parts by weight of a polyester resin component containing one or more ethylenically unsaturated polyester resins which have an acid value of 0 to 50 and a hydroxyl value of 10 to 150 and are the reaction product of
a) 35 to 50 mole % of a carboxylic acid component containing
a1) 5 to 35 mole % of a 1,2-alkenyl dicarboxylic acid monodicyclopentenyl ester,
a2) 50 to 95 mole % of fumaric acid, maleic acid and/or maleic anhydride and
a3) 0 to 20 mole % of a carboxylic acid and/or a carboxylic anhydride other than a1) and a2) with
b) 50 to 65 mole % of an alcohol component containing
b1) 75 to 100 mole % of a dihydric alcohol,
b2) 0 to 25 mole % of a monohydric alcohol and
b3) 0 to 10 mole % of a trihydric alcohol,
B) 20 to 60 parts by weight of a monomer component containing one or more copolymerizable monomers and
C) 0.1 to 10 parts by weight of an initiator component containing one or more photoinitiators, wherein the parts by weight of A) and B) and the percentages of a) and b) each add up to 100.
The present invention also relates to coated substrates, in particular wood or imitation wood, prepared from these compositions at an application viscosity of less than 60 seconds measured at 23° C. in a DIN 4 cup to DIN 53211 under the action of UV radiation.
DETAILED DESCRIPTION OF THE INVENTION
Polyester resins A) have an acid value of 0 to 50, preferably 5 to 40 mg KOH/g; a hydroxyl value of 10 to 150, preferably 10 to 130 mg KOH/g; and a number average molecular weight (M
n
, which may be determined by vapor pressure osmometry) of 300 to 5000, preferably 500 to 2000.
The polyester resins according to the invention are produced using known methods, for example by melt or azeotropic esterification of alcohols and acids or the esterifiable derivatives thereof, c.f. Methoden der organischen Chemie (Houben-Weyl), 4th edition, volume 14/2, Georg Thieme Verlag, Stuttgart 1961, page 1 to 5, 21 to 33, 40 to 44.
The polyester resins are produced by reacting components a1) to a3) and b1) to b3) in the previously disclosed ratios. Component a) preferably contains 6 to 30 mole % of a1), 60 to 94 mole % of a2) and 0 to 15 mole % of a3). Component b) preferably contains 80 to 95 mole % of b1), 5 to 20 mole % of b2) and 0 to 5 mole % of b3). 1,2-alkenyl dicarboxylic acid monodicyclopentenyl ester a1) is the reaction product of maleic acid and dicyclopentadiene and is preferably produced in a preceding stage by heating a mixture of 1.0 mole of maleic anhydride, 1.0 mole of water and 1.0 mole of dicyclopentadiene at a temperature of 80 and 140° C.
Once the remaining components have been added, esterification proceeds under an inert gas atmosphere at temperatures of 140 to 230° C. For the esterification reaction the starting materials are preferably used in quantities corresponding to an OH/COOH equivalent ratio of 1:1 to 1.5:1, in which acid anhydride groups considered for purposes of this calculation as divalent groups.
Component a2) is selected from fumaric acid, maleic acid and/or maleic anhydride.
Component a3) is selected from saturated or unsaturated aliphatic dicarboxylic acids having 4 to 10 carbon atoms other than those set forth for component a2), such as succinic acid, adipic acid, sebacic acid, itaconic acid and/or anhydrides of such acids; cycloaliphatic dicarboxylic acids or dicarboxylic anhydrides having 8 to 10 carbon atoms, such as tetrahydrophthalic acid, hexahydrophthalic acid, norbornene dicarboxylic acid and their anhydrides; aromatic dicarboxylic acids having 8 carbon atoms or their anhydrides, such as phthalic acid, phthalic anhydride, isophthalic acid and terephthalic acid; and aliphatic, cycloaliphatic and/or aromatic monocarboxylic acids having 2 to 10 carbon atoms, such as benzoic acid, acetic acid, cyclohexane carboxylic acid and 2-ethyl-hexanoic acid.
Component b1) is selected from dihydric alcohols having 2 to 15 carbon atoms, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, the isomeric butanediols, neopentyl glycol, 1,6-hexanediol, 2-ethylhexanediol and tripropylene glycol. Ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol and dipropylene glycol are preferred.
Component b2) is selected from monohydric alcohols having 1 to 12 carbon atoms, such as methanol, ethanol, n-hexanol, isooctan
Fischer Wolfgang
Meixner Jürgen
Müller Manfred
Rebuscini Claudio
Bayer Aktiengesellschaft
Eyl Diderico van
Gil Joseph C.
Roy Thomas W.
Weiner Laura
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