Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-08-16
2003-07-15
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S172000, C526S328000, C526S329000, C526S319000, C526S329700, C526S171000
Reexamination Certificate
active
06593440
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel catalyst that is suitable for use in the homopolymerization of norbornenes, in the homopolymerization of acrylates, and in the copolymerization of norbornenes with acrylates. The invention relates, further, to a process for homopolymerizing norbornenes and acrylates using the present catalyst, to a process for copolymerizing norbornenes with acrylates using the present catalyst, and to novel copolymers of norbornenes with acrylates.
BACKGROUND OF THE INVENTION
Considerable interest has existed in the copolymerization of acrylates with norbornenes because of the potential benefits of combining the useful properties of the homopolymers of the two monomers. For example, polyacrylates are valued for their extreme hardness and adhesive properties, and are used to form clear, glass-like materials such as Lucite™ and Plexiglas™. Polynorbornenes, on the other hand, are capable of resisting high temperatures and, thus, typically are employed in applications that necessitate high-temperature stability.
Polymerization of acrylic derivatives is disclosed, for example, in U.S. Pat. No. 4,849,488. In that patent, certain phosphorus compounds are used as polymerization catalysts. Preferred acrylic derivatives that are polymerized in accordance with that patent are acrylates and methacrylates of monovalent and polyvalent alcohols. Copolymers of at least two different acrylic derivatives are also disclosed. There is no disclosure in that patent relevant to the possibility of copolymerizing an acrylic derivative with norbornene or a norbornene derivative.
Until the present invention, attempts to copolymerize acrylates with norbornenes have met with modest success because of a disparity in the mechanisms by which the respective monomers polymerize. U.S. Pat. No. 3,697,490, for example, discloses copolymers of alkoxy alkyl acrylates, alkyl acrylates and substituted norbornene, wherein the copolymers contain only about 0.5 to about 5.5 percent by weight substituted norbornene compounds. The copolymers described in that patent typically are prepared in batch reactions, or the monomers may be proportioned to a reactor containing water and other desired polymerization additives. The patent indicates that best results are generally obtained at polymerization temperatures in the range of 5° C. to 50° C. in the presence of water containing a free radical generating catalyst and surface active agents.
U.S. Pat. No. 6,034,259 broadly discloses a process for polymerizing ethylene, acyclic olefins, and/or selected cyclic olefins, and optionally selected olefinic esters or carboxylic acids. The polymerization reactions are catalyzed by selected transition metal compounds, and sometimes other co-catalysts. Also described in that patent is the synthesis of linear alpha-olefins by the oligomerization of ethylene using as a catalyst system a combination of a nickel compound having a selected alpha-diimine ligand and a selected Lewis or Bronsted acid, or by contacting selected alpha-diimine complexes with ethylene. That patent also discloses polymerization of substituted norbornenes using the disclosed alpha-diimine-containing catalysts systems.
Japanese publication JP040063810 relates to copolymers that contain units derived from three essential monomers, namely: (i) an acrylic ester and/or methacrylic ester monomer, (2) a monomer that possesses a norbornene skeleton, and (iii) a monomer that can be radical-polymerized with the monomer that contains the norbornene skeleton. The copolymers must contain from about 0.5 to about 35 mole % of units derived from radical-polymerizable monomer (iii). The compounds that are disclosed as being suitable for use as the monomer (iii) include esters of maleic acid and an aliphatic alcohol which contains from 1 to 12 carbon atoms, maleic anhydride, N-substituted maleimides, &agr;-cyanocinnamic acid, esters of &agr;-cyanocinnamic acid and an aliphatic alcohol which contains from 1 to 12 carbon atoms, and esters of fumaric acid and an aliphatic alcohol which contains from 1 to 12 carbon atoms. The copolymerization reaction that is described in the Japanese publication typically is conducted in the presence of a free radical polymerization initiator, such as acetyl peroxide, benzoyl peroxide, 2,2′-azobiscyclopropylpropionitrile, or the like.
Typically, acrylates polymerize in the presence of radical or anionic initiators, whereas norbornenes do not follow radical pathways and normally are polymerized by cationic or insertion mechanisms. Therefore, in order to affect the copolymerization of acrylates with norbornenes, it was necessary to develop a catalyst system that would be effective for polymerizing both types of monomers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a catalyst system that is capable of copolymerizing acrylates with norbornenes.
It is another object to provide a catalyst system that is useful for the homopolymerization of both acrylate monomers and norbornenes.
It is yet another object to provide a novel catalyst system that is useful both for the homopolymerizing of acrylate monomers and norbornene monomers, and for the copolymerization of acrylates with norbornenes.
Still another object of the invention is to provide novel copolymers of acrylates with norbornenes.
DETAILED DESCRIPTION OF THE INVENTION
The above and other objects and advantages of the invention are accomplished in one embodiment by providing a Pd(II)-based catalyst system which homopolymerizes acrylates to high molecular weight polymers, which homopolymerizes norbornenes to polymers, and which copolymerizes acrylates with norbornenes to high molecular weight polymers. The copolymers prepared in accordance with this invention are characterized by advantages and properties attributable to the respective acrylate and norbornene monomers from which they are derived. The copolymers can be tailored in norbornene to acrylate ratio by varying the ratio of the respective monomers in the reaction mixture and by varying the ligands utilized in the catalyst system.
The copolymers can be prepared simply by reacting one or more acrylate monomers with one or more norbornene monomers in the presence of the present Pd(II)-based catalyst system. The acrylate and norbornene monomers are the only essential monomers, although additional monomers may be added to the polymerization mixture, provided that they do not interfere with the desired polymerization. Thus, while there may be some instances where it would be desirable to add monomers that can be radical-polymerized with the norbornene monomer, such as the monomers described above in connection Japanese publication JP040063810 as radical-polymerizable monomer (iii), it is preferred to prepare the copolymers of the present invention in the absence of such added monomers.
As used in this specification and claims, the terms “acrylates” is meant to include compounds of the general formula H
2
C═CHCOOR, where R is an alkyl group, such as methyl (CH
3
), ethyl (CH
2
CH
3
), propyl (CH
2
CH
2
CH
3
), n-butyl (CH
2
CH
2
CH
2
CH
3
) or t-butyl (C—(CH
3
)
3
), or an aryl group, such as phenyl (C
6
H
6
) or p-tolyl (C
7
H
8
). Other acrylates which do not conform to the above formula, but which are nonetheless suitable for use in the present invention and are intended to be included within the scope of the term “acrylates”, include such acrylates as 2-hydroxy ethyl methacrylate and methyl methacrylate. Specific, non-limiting examples of acrylates contemplated for use in the present invention include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylamide, 2-hydroxy ethyl methacrylate, methyl methacrylate, acrolein, ethyl methacrylate, acryloyl chloride and phenyl acrylate.
The term “norbornenes” is meant to include norbornene, as well as norbornene derivatives, such as norbomadiene and compounds conforming to the general formulas 5-norbornene-2-R
1a
, 5-norbornene-2,2-R
1a
, 5-norbornene-3-R
1a
, 5-norbornene-3,3-R
1a
, 5-norbor
Hennis April D.
Kacker Smita
Polley Jennifer D.
Sen Ayusman
DeLaurentis PA Anthony J.
Penn State Research Foundation
Zalukaeva Tatyana
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