Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-02-12
2002-07-16
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S454000, C523S455000, C523S456000, C528S088000, C528S089000, C528S090000, C528S091000, C528S408000, C528S418000
Reexamination Certificate
active
06420460
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to thermally and cationically curable compositions containing triarylcyclopropenylium salts. The present invention further relates to the use of triarylcyclopropenylium salts in combinations with coinitiators that interact with the cyclopropenylium cation to release protons, as thermal initiators in the polymerization of epoxy resins, vinyl ethers and other cationically curable compounds.
Triarylcyclopropenylium ions and salts are known from the literature for such wide and varied uses as sensitizers in electrophotographic systems to antibacterial and/or antiviral agents. Triarylcyclopropenylium compounds have often been synthesized, studied and reported in the literature.
Van Tamelen et al., “Photolysis of Triphenylcarbonium, Tropylium and Triphenylcyclopropenylium ions,” J. of Am. Chem. Soc., Vol. 90, No. 5, (1968), Pp. 1372-1374, studied the effect of irradiating compounds with ultraviolet radiation, including triphenylcyclopropenylium ion in considering the formation of products from excited carbonium ions. van Tamelen et al. further disclose irradiation of a triphenylcyclopropenylium ion to form hexaphenylbenzene.
Broser et al., “Substituitierte Tri-Phenyl-Cyclopropenylium-Katlonen,” Tetrahedron Letters, Vol. 7, p. 5331-5332 (1968), reported the production of triphenylcyclopropenylium salts where the phenyl radicals can be substituted by CH
3
, Cl, Br, OH or O—CH
2
—C
6
H
5
. Broser discloses the anions ClO
4
and Br. William Baker in Chemical Abstracts, Vol. 70, p. 262, No. 87088b, Chemical confirmation of the equivalence of carbon atoms of the three-membered ring of the triphenylcyclopropenylium cation, (1969) also reports on the production of the bromide salt of triphenylcyclopropenylium. Furthermore, D'yakonov in Chemical Abstracts, Vol. 72, p. 342, No. 110857, showed the equivalence of the carbon atoms of the three membered ring of the triphenylcyclopropenylium cation, in a paper that discloses the production of both the chloride and bromide salts of triphenylcyclopropenylium.
French Patent No. 2,013,105 made available to the public Mar. 27, 1970, discloses a photoconductor sensitized with a cyclopropenylium salt, specifically the triphenylcyclopropenylium salt. The patent discloses that aryl radicals can be substituted or unsubstituted by, for example, phenyl, chlorophenyl, or tolyl. The disclosed anions include perchlorate, fluoroborate, sulfonate, periodate, and halides such as chloride, bromide and iodate.
U.S. Pat. No. 3,728,388 discloses 1,2,3-trisubstituted cyclopropenylium salts having antibacterial and antiviral activity. More specifically, it describes a triphenylcyclopropenylium salt, the anion being any anion of a strong inorganic or organic acid, such as bromide, chloride, iodide, sulfate, tetrafluoroborate, perchlorate, p-toluenesulfonate, or methanesulfonate.
Frisch et al., “An Unusual Oxidative Addition-Ligant Ellimination Reaction. Preparation and Structure of RhCl
2
(Pme
2
Ph)
2
(C
2
Ph
3
),” J. of Organometallic Chemistry, No. 142, Pp. C61-C64 (1977), discloses a triphenylcyclopropenylium cation (C
3
Ph
3
+
) stabilized as the Cl
−
or PF
a
−
salt.
Komatsu et al., “Syntheses of Mono-, Bis-, and Tris(diisopropylamino)triphenylcyclopropenylium ions. Cyclopropenyl Analogues of Triphenylmethane Dyes,” discloses an unsubstituted triphenylcyclopropenylium ion and triarylcyclopropenylium ions with dialkylamino substituents, (i.e. mono-, bis- and tris-(dilsopropylamino)triphenylcyclopropenylium ions, and mono- and bis-(dimethylamino) triphenylcyclopropenylium ions). Anions can be ClO
4
(perchlorate) or BF
4
(tetrafluoroborate). The disclosed use of these compounds is as dyes.
Gompper et al., “&sgr;-(Dicarbonyl-cyclopentadienyl-eisen)-Derivate von Cyclopropenen und Cyclopropenyliumsalzen” discloses triphenylcyclopropenylium salt, the anion being BF
4
or Br. It also describes a diphenyl cyclopropenylium salt. The anion being BF
4
, Br or SbCl
6
.
Finally, U.S. Pat. No. 3,552,958 discloses sensitizers for organic photoconductors containing cyclopropenylium compositions. The objects are accomplished through the use of cyclopropenylium salts containing aryl and/or heterocyclic radicals. The anions are perchlorate, fluoroborate, sulfonate, periodate, and halides such as chloride, bromide and iodide.
SUMMARY OF THE INVENTION
A thermally curable composition comprising: (a) a compound of the Formula I:
where Ar is an aryl group which may be the same or different; and X is an anion selected from the group consisting of Cl
−
, F
−
, Br
−
, I
−
, CF
3
CO
2
−
, CH
3
CO
2
−
, CF
3
SO
3
−
, ArSO
3
−
, ClO
4
−
, BF
4
−
, PF
6
−
, SbF
6
−
, AsF
6
−
, B(C
6
F
5
)
−
, and B(Ar)
4
−
,
(b) a cationically curable compound and
(c) a coinitiator that interacts with the compound of Formula I and releases a proton. The terms “cure” and “curable” as used herein refer to hardening by polymerization or cross-linking.
There is further disclosed a method comprising heating the composition described above to obtain a cured composition. Heating will typically be conducted at temperatures of about 30 to 60° C. for a time sufficient to cure the curable compound.
DETAILED DESCRIPTION
The present invention relates to the use of triarylcyclopropenylium compounds of the Formula I in the thermal initiation of cationic polymerization reactions.
In compounds of Formula I Ar may be mononuclear, polynuclear, or heterocylic. Ar may be selected from the group consisting of substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted tolyl and substituted or unsubstituted benzyl. In one embodiment, Ar may be selected from the group consisting of phenyl, chlorophenyl, tolyl, naphthyl and the like. Ar may be substituted from 0 to 5 times with one or more alkyl groups (typically having 1 to 10 carbon atoms) that may be same or different. Ar may contain one or more heteroatoms selected from, for example, nitrogen, oxygen or sulfur. Examples of compounds of Formula I include triphenylcyclopropenylium chloride, triphenylcyclopropenylium hexafluoroantimonate, triphenylcyclopropenylium tetrakis(pentafluorophenyl)borate, and triphenylcyclopropenylium hexafluorophosphate.
The synthesis of triarylcyclopropenylium halides is known in the art and is illustrated in Example 1. The triarylcyclopropenylium compounds may be made by reacting a triarylcyclopropenylium halide with a salt of the desired anion, e.g., SbF
6
−
, AsF
6
−
, and B(C
6
F
5
)
4
−
.
The triarylcyclopropenylium compound is used with a coinitiator such as carbonyl compound or other Lewis base, such as an alcohol, that can release a proton in the thermal initiation of polymerization of one or more cationically curable compounds. The Lewis base may be in the form of the monomer or may be in the form of a solvent. It may be a carbonyl group containing compound with at least one hydrogen atom &agr; to the carbonyl group. Alternatively it may be an alcohol, a thiol or an amine that contains an acidic hydrogen. It has been observed that the polymerization or cure rate of compositions of the invention increases with the ratio of the Lewis base, for example the carbonyl compound, to the triarylcyclopropenylium compound. Based upon this observation the following mechanism is postulated for proton generation when the Lewis base is the carbonyl group containing compound, cyclohexanone:
The coinitiator is believed to form a complex (such as 1) that is sufficiently acidic that it releases a proton. This mechanism is supported by the observation of compound 2 by other workers in subsequent experiments.
Thermally curable compositions in accordance with one embodiment of the invention may contain about 0.5 to 2 parts by weight triarylcyclopropenylium per 100 parts monomer and in some of the more typical embodiments may contain about 1 part per 100 parts of curable compound. The carbonyl compound should be present in at least an equi
Malpert John H.
Martin Dustin B.
Neckers Douglas C.
Zhang Wenqin
Aylward D.
Dawson Robert
Thompson Hine LLP
UCB S.A.
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