Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-02-07
2003-02-18
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S258000, C526S271000, C526S279000, C526S281000, C526S284000, C526S306000
Reexamination Certificate
active
06521731
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to compositions containing polycyclic olefins which polymerize under free-radical conditions to generate crosslinked polymers and copolymers. The invention relates particularly to polycyclic olefins which primarily contain bicycloheptenyl unsaturation units.
BACKGROUND OF THE INVENTION
Polymers and copolymers synthesized from polycyclic olefin monomers have attracted much interest from the scientific community due to the desirable properties often exhibited by these materials. Cyclic olefin copolymers (COC's) possess a unique combination of properties such as low density, low moisture absorption, low birefringence, high transparency, and high strength. Depending on the polycyclic olefin monomer and the polymerization conditions, materials can also be produced having a wide range of glass transition temperatures. As a result, these materials are being tested for use in diverse applications such as electronics, CD-ROM disks, optical lenses, barrier films, and medical appliances.
A particularly attractive characteristic displayed by polycyclic olefin monomers is the ability to polymerize via a variety of reaction mechanisms. It is well-known that polycyclic olefins can be polymerized and/or copolymerized free-radically, cationically, or coordinatively using organometallic catalysts. Due to this mechanistic flexibility, a wide variety of functionalized comonomers can be incorporated into the cyclic olefin copolymer, which provides further control over the bulk properties of the material.
Since polycyclic olefin monomers have the ability to polymerize free-radically, these monomers have been explored as potential candidates for use in free-radical cured thermosetting compositions. Indeed, polycyclic olefins have been shown to readily copolymerize with electron deficient olefins. Thermosetting resins incorporating polycyclic olefins can be expected to have many desirable properties, such as high Tg, hydrophobicity, and low shrinkage upon cure. However, in order to obtain these desirable properties in a thermoset resin, the polycyclic olefin must be of a certain minimum molecular weight (i.e., the volatility of the olefin should be low) and must be sufficiently reactive with the propagating free radicals during cure to produce a highly crosslinked thermoset network.
Unfortunately, most common and inexpensive polycyclic olefin monomers, such as norbornene, norbornadiene, dicyclopentadiene (DCPD), and the like, are deficient in these areas. Specifically, norbornene, norbornadiene, and DCPD are too volatile for use in many thermoset applications. In addition, the cyclopentenyl unsaturation of DCPD is insufficiently reactive for many thermoset applications. Indeed, it is well known that the cyclopentenyl double bond is far less reactive than the norbornenyl double bond, due to the low ring strain associated with the cyclopentenyl ring (relative to the bicycloheptenyl group). Moreover, the allylic hydrogen atoms on the cyclopentenyl rings may contribute to chain transfer reactions, thereby reducing the molecular weight of the growing polymer chains during cure. Thus, optimum free-radically cured thermosets incorporating polycyclic olefins are only produced when the polycyclic olefin has low volatilty and contains little, if any, cyclopentenyl unsaturation.
Accordingly, there is a need for polycyclic olefin monomers which can be readily incorporated into free-radically cured thermosetting resin compositions, thereby producing thermosets having a unique combination of beneficial properties.
BRIEF DESCRIPTION OF THE INVENTION
In accordance with the present invention, there are provided free-radically polymerizable compositions comprising polycyclic olefins, wherein the polycyclic olefins contain little, if any, cyclopentenyl unsaturation. As a result, these olefins are sufficiently reactive with the propagating free-radicals during cure to provide a highly crosslinked thermoset resin. Moreover, invention compositions comprise high molecular weight polycyclic olefins having low volatility. Accordingly, the undesirable weight loss upon cure observed with many thermosetting compositions is considerably reduced.
Further provided by the present invention are compositions comprising functionalized polycyclic olefin monomers. These functionalized olefin monomers provide additional benefits such as increased adhesion to a variety of surfaces as well as greater control over glass transition temperatures.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, there are provided free-radically polymerizable compositions comprising
(A) at least one polycyclic olefin monomer, said monomer having at least one terminal norbornenyl functional group, wherein said monomer contains little, if any, cyclopentenyl unsaturation,
(B) a maleimide or succinimide,
(C) optionally, one or more free radical curing co-monomers, and
(D) in the range of 0.2 up to 5 wt % of at least one curing catalyst, based on the total weight of the composition.
In one embodiment, polycyclic olefin monomers contemplated for use in the practice of the present invention have the following structures:
wherein each R is
(a) independently hydrogen or substituted or unsubstituted alkyl, and each x is independently 0, 1 or 2, or
(b) —X—Y,
wherein:
X is an optional bridging group
Y is a maleimide, a substituted maleimide, an epoxy group, an oxazoline, a cyanate ester-substituted aryl, or an oxazine, and
n≦about 8.
In preferred embodiments, X is an alkylene or oxyalkylene comprising up to about 20 atoms, or X is a siloxane, and Y is an optionally substituted maleimide or oxazine. In a particularly preferred embodiment, Y is a benzoxazine.
In another embodiment, polycyclic olefin monomers contemplated for use in the practice of the present invention have the following structure:
wherein:
R, x, and n are as defined above, and
Q is a bridging group selected from siloxane,
wherein R′ is an alkylene, an arylene or a polycyclic hydrocarbyl. In preferred embodiments, Q is a tetramethyldisiloxane.
Maleimides contemplated for use in the practice of the present invention as component (B) have the following structure:
wherein:
R is hydrogen or lower alkyl
J— is:
(1) saturated straight chain alkyl or branched chain alkyl, optionally containing optionally substituted aryl moieties as substituents on said alkyl chain or as part of the backbone of said alkyl chain, and wherein said alkyl chains have up to about 20 carbon atoms,
(2) aromatic groups having the structure:
wherein:
each Ar is a monosubstituted, disubstituted or trisubstituted aromatic or heteroaromatic ring having in the range of 3 up to 10 carbon atoms, and Z is:
(i) saturated straight chain alkylene or branched chain alkylene, optionally containing saturated cyclic moieties as substituents on said alkylene chain or as part of the backbone of the alkylene chain, or
(ii) polyalkylene oxides having the structure:
—[(CR
2
)
r
—O—]
q
—(CR
2
)
s
—
wherein each R is independently as defined above, r falls in the range of 1 up to 10, s falls in the range of 1 up to 10, and q falls in the range of 1 up to 50,
(3) di- or tri-substituted aromatic moieties having the structure:
wherein each R is independently as defined above, t falls in the range of 2 up to 10, u falls in the range of 2 up to 10, and Ar is as defined above,
(4) polyalkylene oxides having the structure:
[(CR
2
)
r
—O—]
q
—(CR
2
)
s
—
wherein each R is independently as defined above, and wherein each of r, s and q are as defined above,
(5) a polycyclic olefinyl, or
(6) mixtures of any two or more thereof, and
m is 1, 2, or 3.
In preferred embodiments, the maleimide is N-methylmaleimide, N-ethymaleimide, N-propylmaleimide, N-butylmaleimide, N-t-butylmaleimide, N-hexylmaeimide, N-2-ethylhexylmaleimide, N-cyclohexylmaleimide, N-octylmaleimide, N-decylmaleimide, N-dodecylmaleimide, N-phenylmaleimide, 2-methyl-N-phenylmaleimide, 4-methyl-N-phenylmaleimide, 2-ethyl-N-phenylmaleimide, 4-ethyl-N-phenylmaleimide, 2,6-diethy
Dershem Stephen M.
Forrestal Kevin J.
Foley & Lardner
Henkel Loctite Corporation
Pezzuto Helen L.
Reiter Stephen E.
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