Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-07-18
2003-08-26
Berman, Susan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S026000, C522S030000, C522S148000, C522S170000, C528S012000, C528S033000, C428S352000
Reexamination Certificate
active
06610760
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to radiation curable silicone compositions, more particularly to radiation curable silicone compositions that exhibit very rapid cure speed.
BRIEF DESCRIPTION OF THE RELATED ART
Radiation curable systems that are based on iodonium salt catalyzed epoxy-functional silicone polymers and are useful for release coating applications are well known, see, for example, coassigned U.S. Pat. No. 4,279,717.
Increasing the speed at which such systems may be cured has been a topic of great interest. One approach has been to include cure speed enhancing additives, such as for example, photosensitizers, to such compositions. Iodonium cationic photocatalysts typically exhibit peak absorption at wavelengths less than 250 nanometers (“nm”) and do not absorb or otherwise respond to radiation of wavelength greater than 300 nm. Thioxanthones which absorb light in the 300 to 400 nm range have been shown to be effective photosensitizers for iodonium photocatalysts in epoxysilicone-based formulations, see, for example, coassigned U.S. Pat. No. 5,650,453. Visible light photosensitizers for iodonium salt-catalyzed cationic curing systems are also known, see, for example, U.S. Pat. No. 4,250,053 and U.S. Pat. No. 4,356,050. However, the solubility of such materials in nonpolar epoxysilicone media is generally limited, so that their potential use for photocurable silicone applications is typically limited to very highly functionalized silicone polymers and monomers.
There remains a continuing interest in providing radiation curable silicone compositions that exhibit improved properties, such as for example, more rapid cure speed.
SUMMARY OF THE INVENTION
The present invention is directed to a radiation curable composition, comprising an epoxy-functional silicone polymer, a photocatalyst, and a cure speed-enhancing amount of a non-fluorescing polycyclic aromatic compound, said polycyclic aromatic compound comprising at least one hydroxyl, alkoxy or glycidyl ether substituent bonded to an aromatic carbon atom of the compound.
The composition of the present invention exhibits improved cure speed.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment, the composition of the present invention comprises, based on 100 parts by weight (“pbw”) of the composition, from 90 pbw to 99.9 pbw, more preferably from 95 pbw to 99.5 pbw, and still more preferably from 96 pbw to 99 pbw, of the epoxy-functional silicone polymer, from 0.05 pbw to 8 pbw, more preferably from 0.2 pbw to 5 pbw, and still more preferably from 0.5 pbw to 2 pbw, of the photocataylst and from 0.05 pbw to 2 pbw, more preferably from 0.1 pbw to 2 pbw, and still more preferably from 0.2 pbw to 1 pbw, of the non-fluorescing polycyclic aromatic compound.
Compounds suitable as the polycyclic aromatic compound of the composition of the present invention are those aromatic hydrocarbon compounds comprising two or more hydrocarbon rings, preferably at least two of which are fused rings, that is, rings joined such that each of the fused rings shares two or more carbon atoms with at least one other ring, which contain the maximum possible number of conjugated double bonds for number of carbon atoms contained in the rings and which contain at least one hydroxy, alkoxy or glycidyl ether substituent bonded to an aromatic carbon atom of the compound.
Polycyclic aromatic compounds suitable for use as the polycyclic aromatic compound of the present invention include, for example, hydroxypentalenes, hydroxyindenes, naphthols, dihydroxynaphthalenes, alkoxynaphthols, alkoxynaphthalenes, alkoxydihydoxynaphthalenes, glycidyl naphthalene ethers, hydroxyazulenes, alkoxyazulenes hydroxyphenanthrenes, alkoxyphenanthrenes, hydroxyanthracenes, alkoxyanthracenes, hydroxyanthrols and alkoxyanthrols.
In a preferred embodiment, the polycyclic aromatic compound comprises one or more compounds of the structural formula (I):
wherein R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
and R
8
are each independently H, halo, hydroxy or a monovalent hydrocarbon radical, provided that at least one of R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
and R
8
is hydroxy, alkoxy or a monovalent glycidyl ether radical.
As used herein, the terminology “monovalent hydrocarbon radical” includes monovalent acyclic hydrocarbon radicals, monovalent alicyclic hydrocarbon radicals and monovalent aromatic hydrocarbon radicals.
As used herein, the terminology “monovalent acyclic hydrocarbon radical” means a monovalent straight chain or branched hydrocarbon radical, preferably containing from 2 to 20 carbon atoms per radical, which may be saturated or unsaturated and which may be optionally substituted or interrupted with one or more functional groups, such as, for example, amino, carboxyl, cyano, hydroxy, halo, mercapto, and oxy. Suitable monovalent acyclic hydrocarbon radicals include, for example, alkyl such as, for example, methyl, ethyl, sec-butyl, tert-butyl, octyl, dodecyl or stearyl; alkoxy, such as, for example, methoxy or ethoxy; hydroxyalkyl, such as, for example, hydroxyethyl or hydroxypropyl; alkenyl, such as, for example, ethenyl or propenyl; alkynyl, such as, for example, propynyl or butynyl; cyanoalkyl, such as for example, cyanomethyl or cyanoethyl; carboxyalkyl, such as, for example, carboxymethyl or carboxypropyl; alkylamido such as, for example, methylamido or dodecylamido; and haloalkyl, such as, for example, chloromethyl, 2-fluoropropyl, 2,2-difluropropyl or 3,3,3-trifluoropropyl, as well as monovalent glycidyl ether radicals. As used herein the terminology “monovalent glycidyl ether radical” means a monovalent radical containing at least one oxygen atom substituted with at least one glycidyl-containing moiety, such as, for example, glycidyloxy or glycidylalkyloxy, including, for example, glycidylethyloxy or glycidylpropyloxy.
As used herein, the terminology “monovalent alicyclic hydrocarbon radical” means a monovalent radical containing one or more saturated hydrocarbon rings, preferably containing from 4 to 10 carbon atoms per ring, per radical which may optionally be substituted on one or more of the rings with one or more functional groups, such as for example, alkyl, halo or alkylene groups, each preferably containing from 2 to 6 carbon atoms per group, and which, in the case of two or more rings, may be fused rings. Suitable monovalent alicyclic hydrocarbon radicals include, for example, cyclohexyl and cyclooctyl.
As used herein, the terminology “monovalent aromatic hydrocarbon radical” means a monovalent hydrocarbon radical containing at least one aromatic ring per radical, which may optionally be substituted on the aromatic ring with one or more functional groups, such as for example, alkyl, halo or alkylene groups, each preferably containing from 2 to 6 carbon atoms per group. In a preferred embodiment, the monovalent aromatic hydrocarbon radical is monocyclic, that is, contains only one aromatic ring per radical. Suitable monovalent aromatic hydrocarbon radicals include, for example, phenyl, tolyl, 2,4,6-trimethylpheny and 1,2-isopropylmethylphenyl.
In a preferred embodiment, at least two, more preferably, two, of R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
and R
8
are each independently hydroxy, alkoxy or a monovalent glycidyl ether radical.
As used herein the notation “(Cx-Cy)”, wherein x and y are each positive integers, in reference to an organic compound or substituent group means that the compound or substituent group may contain from x carbon atoms to y carbon atoms per compound or group.
In a preferred embodiment, R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
and R
8
are each independently H, hydroxy, alkyl, preferably (C
1
-C
6
)alkyl, alkoxy, preferably (C
1
-C
6
)alkoxy, a monovalent glycidyl ether radical, preferably glycidyloxy, or alkylamido, preferably (C
1
-C
18
)alkylamido, provided that at least one of R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
and R
8
is hydroxy, alkoxy or a monovalent glycidyl ether radical.
In a highly preferred embodiment, one or more of R
1
, R
2
, R
3
, R
4
, R
5
, R
6
, R
7
and R
8
are each
Eckberg Richard Paul
Feng Kesheng
Neckers Douglas
Berman Susan W.
General Electric Company
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