Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-08-19
2002-09-17
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S312000, C526S319000, C526S320000, C526S323100, C526S329600, C525S259000, C525S263000, C525S264000, C524S081000, C524S358000, C524S315000, C524S365000
Reexamination Certificate
active
06451948
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to radical-curable adhesive compositions which include a (meth)acrylate component; a thermal resistance-conferring component; and a radical cure-inducing composition. Reaction products of the compositions of this invention exhibit superior resistance to thermal degradation.
2. Brief Description of Related Technology
Radical-curable adhesive compositions generally are well-known. In the context of anaerobic adhesives, see e.g., R. D. Rich, “Anaerobic Adhesives” in
Handbook of Adhesive Technology,
29, 467-79, A. Pizzi and K. L. Mittal, eds., Marcel Dekker, Inc., New York (1994) and references cited therein. In the context of radiation-curable adhesives, see e.g., J. G. Woods, “Radiation Curable Adhesives” in
Radiation Curing: Science and Technology,
333-98, S. P. Pappas, ed., Plenum Press, New York (1992).
Uses of radical-curable adhesives are legion and new applications continue to be developed.
In the past, many adhesives particularly anaerobic adhesives, have been rendered resistant to degradation at elevated temperatures by the inclusion of certain additives.
For instance, U.S. Pat. No. 3,988,299 (Malofsky) refers to a heat curable composition having improved thermal properties, which includes certain acrylate monomers and maleimide compounds.
L. J. Baccei and B. M. Malofsky, “Anaerobic Adhesives Containing Maleimides Having Improved Thermal Resistance” in
Adhesive Chemicals,
589-601, L-H, Lee, ed., Plenum Publishing Corp. (1984) report the use of maleimides—specifically, N-phenyl maleimide, m-phenylene dimaleimide and a reaction product of methylene dianiline and methylene dianiline bismaleimide—to increase the thermal resistance of anaerobic adhesives which are fully cured at temperatures of at least 150° C.
U.S. Pat. No. 4,216,134 (Brenner) speaks to one-component anaerobic adhesive compositions which include ethylenically unsaturated diluent monomers (such as styrene, divinylbenzene, diallyl carbonates, diallyl maleate, diallyl phthalate, diallyl isophthalate and the like), prepolymers (such as 1,2-polybutadienes and copolymers thereof, isophthalic polymers, bisphenol A fumates, epoxy resins, polyallylvinyl ethers and the like) and triallyl cyanurate or triallyl isocyanurate as reaction components. The '134 patent is at least a three component composition (in addition to its cure components) and requires a prepolymer which may be included in addition to or as a replacement for the ethylenically unsaturated diluent monomer. Examples of the prepolymer are given as “high vinyl 1,2-polybutadienes and copolymers thereof especially styrene; isophthalic polymers; bisphenol A fumates and other alkyls; epoxy resins; polyalkyl vinylethers and related polymers; alkylic resins based on polyfunctional ethers and esters and mixtures of two or more of these prepolymers.” (Col. 5, lines 32-39.)
While the addition to radical-curable adhesive compositions of such maleimide compounds to render them resistant to thermal degradation provides reaction products with acceptable performance, it would be desirable to find alternative compounds to include in such formulations. Moreover, in certain adhesive compositions, maleimides (which tend to be, insoluble) often function to reduce radiation penetration thereby inhibiting photoinitated cure of acrylate-based compositions.
U.S. Pat. No. 4,540,829 (Heffner) speaks to alkylated di and polycyclopentadiene diphenols.
U.S. Pat. No. 5,495,051 (Wang) speaks to certain phenol alkyl ethers, their preparation and cure together with bismaleimides.
U.S. Pat. No. 5,166,290 (Hayashi) describes a resin composition for composites that requires a bismaleimide mixture with certain allyl phenyl ethers.
U.S. Pat. No. 5,084,490 (McArdle) and U.S. Pat. No. 5,141,970 (McArdle) describe polyfunctional cationically polymerizable styryloxy compounds, curable compositions including such styryloxy compounds and methods of forming high-temperature resistant polymers therefrom. These compounds may be described in more detail with reference to structure I:
where R
1
and R
2
are H, or one of R
1
and R
2
is H and the other is alkyl; R
3
and R
4
(which may be the same or different) are H, C
1-5
alkyl or C
1-5
alkenyl; or one of R
3
and R
4
may be —OR
5
or C
1-5
alkoxy or C
1-5
alkenyloxy, if R
2
is not methyl; and R
5
is selected from
where R
6
is C
1-5
alkyl, and R
7
, R
8
and R
9
may be the same or different and are H or C
1-5
alkyl.
These cationically curable propenyloxystyrene compounds possess outstanding thermal and mechanical properties in their cured state. To reach the cured state, the compounds undergo a 2-stage curing process involving an initial acid catalyzed addition polymerization or copolymerization of the styrene group (called A-stage polymerization), followed by a heat-triggered, post-curing reaction of the propenyloxyphenyl group (called B-stage polymerization). During the post-curing reaction, the A-stage polymer rearranges to form a reactive phenolic polymer, which spontaneously reacts with the propenyloxy group through an electrophilic substitution reaction. This results in the formation of a cross-linked polymer that exhibits a high decomposition temperature (“T
d
”) [T
d
>400° C., as measured by thermal gravimetric analysis (“TGA”)], a high glass transition (“T
g
”) [T
g
>300° C., as measured by dynamic mechanical analysis (“DMA”)] and good adhesion. See also J. Woods et al., “Alkenyloxy Styrene Monomers for High-Temperature Adhesives and Sealants” in
Photopolymerization,
ch. 9, pp. 107-20 (1997).
While this information describes styryloxy and propenyloxystyrene compounds and suggests their usefulness as adhesives, sealants and/or coatings and/or in compositions destined for such use, their use to confer resistance to thermal degradation on such compositions, particularly (meth)acrylate-containing radical-curable adhesive compositions, remained unknown until the discovery of the invention described herein.
U.S. Pat. No. 5,369,200 (Schadeli) describes terpolymers of two different maleimide monomers and an olefinically unsaturated phenyl ether monomer in which the phenyl ether is defined by an acid cleavable group —OR
2
linked to a phenyl ring. Examples of such monomers are given as a terpolymer of 4-(2-tetrahydropyranyloxy) benzyl methacrylate, N-hydroxymethylmaleimide and N-(acetoxymethyl)maleimide. The terpolymers are used as positive resists with acid generating photocatalysts and therefore it is imperative that the OR
2
group be selected to be acid cleavable.
U.S. Pat. No. 4,387,204 (Zahir) and U.S. Pat. No. 4,468,524 (Zahir) describe alkenylphenyl substituted acrylates or methacrylates and cross-linkable compositions thereof.
Notwithstanding the state-of-the-technology, there is an on-going search for additives to improve the thermal performance of reaction products of radical-curable adhesives. In addition, it would be desirable to provide alternatives, replacements and/or supplements for maleimide-type materials for improving the resistance to thermal degradation of reaction products of radical-curable adhesive compositions.
In particular, it would be desirable to provide additives that tend to be soluble which would lead to adhesive compositions having improved homogenity.
SUMMARY OF THE INVENTION
The present invention meets the desire discussed above by providing radical-curable adhesive compositions, reaction products of which exhibit superior performance at elevated temperatures. The compositions include a (meth)acrylate component; a thermal resistance-conferring component; and a radical cure-inducing composition.
Within the thermal resistance-conferring component are polymerizable aromatic materials having at least one Claisen rearrangable functional group. Such Claisen rearrangable functional groups include allyloxy and allylthiol groups, where the oxygen and the sulfur, respectively, are bound to the aromatic ring. Desirably, such polymerizable aromatic materials should include at least two re
Jacobine Anthony F.
Morrill Susanne D.
Woods John G.
Bauman Steven C.
Loctite Corporation
Wu David W.
Zalukaena Tatyana
LandOfFree
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