Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-02-12
2004-02-03
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S079000, C526S087000, C526S262000, C526S279000, C526S308000, C525S326500, C525S333300, C525S338000
Reexamination Certificate
active
06686430
ABSTRACT:
TECHNICAL FIELD
This invention relates to a novel alicyclic hydrocarbon copolymer exhibiting low birefringence and excellent mechanical strength, a process for producing the alicyclic hydrocarbon copolymer, and a resin composition comprising the alicyclic hydrocarbon copolymer.
BACKGROUND ART
A hydrogenated aromatic vinyl polymer prepared by hydrogenating aromatic rings of an aromatic vinyl polymer such as polystyrene, and a hydrogenated aromatic vinyl copolymer prepared by hydrogenating a copolymer of an aromatic vinyl compound with a vinyl compound are known as an optical material exhibiting low birefringence.
For example, it is described in Japanese Unexamined Patent Publication No. H1-317728 that an optical disk substrate having low birefringence is made from a hydrogennated polystyrene resin or a hydrogenated styrene-butadiene-styrene block copolymer.
In recent years, these hydrogenated aromatic vinyl polymers have been proposed for use in a pick-up lens for reading signal of an optical disk as well as in an optical disk substrate, because these hydrogenated aromatic vinyl polymers exhibit high transparency, high heat resistance and low water absorption. Nevertheless, a far reduced birefringence is required for a pick-up lens for reading signal of an optical disk having a high recording density such as an optical disk for the following generation. But, the pick-up lens for reading signal of an optical disk having a high recording density has a complicated shape and thus the birefringence tends to be undesirably high.
In general, the birefringence of optical parts varies depending upon the birefringence inherently possessed by a material used and the residual stress at shaping. It is impossible to reduce the birefringence inherently possessed by a material used, and therefore, it is required to reduce the residual stress by enhancing fluidity of a resin material, for example, by employing a resin material having a low molecular weight or elevating a resin-shaping temperature. However, the resin material having a low molecular weight gives a shaped article having poor mechanical strength and the birefringence cannot be reduced to the extent desired for optical disks for the following generation.
In international publication WO96/28660, a catalyst is described which exhibits an activity for hydrogenating the backbone chain and aromatic rings in a copolymer such as a random copolymer or tapered block copolymer of an aromatic vinyl compound with a chainlike vinyl compound. A specific working example using the catalyst is described wherein a copolymer containing at least 90% by weight of butadiene units is hydrogenated. However, the resulting copolymer does not exhibits a sufficiently low birefringence, and has low glass transition temperature and poor mechanical strength, and thus, is of no practical use as optical material.
DISCLOSURE OF THE INVENTION
In view of the foregoing, a primary object of the present invention is to provide a novel alicyclic hydrocarbon polymer having low birefringence and enhanced mechanical strength, and a process for producing the novel alicyclic hydrocarbon polymer.
Thus, in accordance with the present invention, there is provided an alicyclic hydrocarbon copolymer having a weight average molecular weight in the range of 1,000 to 1,000,000 and comprising repeating units (a) represented by the following general formula (1), and at least one kind of repeating units (b) selected from those which are represented by the following general formula (2) and/or the following general formula (3); the sum of repeating units (a) and repeating units (b) being at least 90% by weight based on the weight of the copolymer, and the content of repeating units (b) being at least 1% by weight but smaller than 10% by weight, based on the weight of the copolymer; and the chain of repeating units (a) satisfying the following formula:
A
≦0.3
×B
where A=weight average molecular weight of the chain of repeating units (a), and
B=weight average molecular weight (Mw) of the alicyclic hydrocarbon copolymer×(number of repeating units (a)
umber of the total repeating units constituting the alicyclic hydrocarbon copolymer),
wherein X in formula (1) is an alicyclic hydrocarbon group, R1 through R13 in formulae (1), (2) and (3) independently represent a hydrogen atom, a chainlike hydrocarbon group, a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group, a silyl group, and a chainlike hydrocarbon group having one or more polar groups as a substituent which are selected from a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group and a silyl group; and
in formula (3) represents a carbon-carbon saturated or unsaturated bond.
The chain of repeating units (a) represented by formula (1) preferably satisfies the following formula:
A/C
≧1.3
where A=weight average molecular weight of the chain of repeating units (a), and
C=number average molecular weight of the chain of repeating units (a).
In accordance with the present invention, there is further provided a process for producing an alicyclic hydrocarbon copolymer comprising:
a step of copolymerizing an aromatic vinyl compound and/or an alicyclic vinyl compound (a′) with other copolymerizable monomer (b′) to obtain a hydrocarbon copolymer satisfying the following formula:
D
≦0.3
×E
where D=weight average molecular weight of the chain of repeating units derived from the aromatic vinyl compound and/or the alicyclic vinyl compound, and
E=weight average molecular weight (Mw) of the alicyclic hydrocarbon copolymer×(number of repeating units derived from the aromatic vinyl compound and/or the alicyclic vinyl compound
umber of the total repeating units constituting the alicyclic hydrocarbon copolymer); and
a step of hydrogenating carbon-carbon unsaturated bonds in the unsaturated rings and the backbone chain of the alicyclic hydrocarbon copolymer.
BEST MODE FOR CARRYING OUT THE INVENTION
1. Alicyclic Hydrocarbon Copolymer
The alicyclic hydrocarbon copolymer of the present invention is characterized as comprising repeating units (a) represented by the following general formula (1) and repeating units (b) represented by the following general formula (2) and/or the following general formula (3), and, if desired, other repeating units (c).
wherein R1 through R13 in formulae (1), (2) and (3) independently represent a hydrogen atom, a chainlike hydrocarbon group, a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group, a silyl group, and a chainlike hydrocarbon group having one or more polar groups as a substituent which are selected from a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group and a silyl group. Of these, a hydrogen atom and a chainlike hydrocarbon group having 1 to 6 carbon atoms are preferable in view of enhanced heat resistance and reduced water absorption. The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and a iodine atom. The chainlike hydrocarbon group having a polar group as a substituent includes, for example, a halogenated alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms and more preferably 1 to 6 carbon atoms. The chainlike hydrocarbon group includes, for example, an alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms and more preferably 1 to 6 carbon atoms, and an alkenyl group having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms and more preferably 2 to 6 carbon atoms.
X in formula (1) is an alicyclic hydrocarbon group. The number of carbon atoms in X is usually in the range of 4 to 20, preferably 4 to 10 and more preferably 5 to 7. When the number of carbon atoms in the alicyclic hydrocarbon group is in this range, the birefringence can be reduced to a considerable extent
Armstrong Kratz Quintos Hanson & Brooks, LLP
Teskin Fred
Zeon Corporation
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