Cyclic olefin copolymer, resin composition, and molded body

Abstract

The purpose of the present invention is to provide a cyclic olefin copolymer having both a high refractive index and a low Abbe number. This cyclic olefin copolymer contains a structural unit (A) derived from a C2-10 alpha-olefin, a structural unit (B) derived from a cyclic olefin, and a structural unit (C) derived from an aromatic vinyl compound. The value obtained by dividing the total number of aromatic rings contained in the cyclic olefin copolymer by the number of all repeating units in the cyclic olefin copolymer is 0.25 or more.

Description

Cyclic olefin copolymer, resin composition, and molded article

[0001] The present invention relates to a cyclic olefin copolymer, a resin composition, and a molded article.

[0002] Cyclic olefin copolymers have attracted attention as molding materials applicable to various applications including optical applications due to their excellent optical properties such as transparency, heat resistance, and low birefringence, as well as moldability and chemical resistance. Accordingly, in recent years, various proposals have been made to improve the physical properties of cyclic olefin copolymers.

[0003] Specifically, for example, Patent Document 1 discloses a cyclic olefin copolymer having structural units derived from an α-olefin having 2 to 20 carbon atoms, structural units derived from a cyclic olefin, and structural units derived from an aromatic vinyl compound represented by a specific chemical formula. According to Patent Document 1, the cyclic olefin copolymer has a high refractive index and can be adjusted to have a lower Abbe number than conventional resin materials.

[0004] International Publication No. 2019 / 188447

[0005] In recent years, from the viewpoint of increasing the degree of freedom in optical design, there has been a demand for the development of cyclic olefin copolymers having a low Abbe number (for example, 40 or less) as optical materials used in molding optical elements such as lenses. In addition, cyclic olefin copolymers used as materials for various molded articles such as optical elements are also required to have a high refractive index.

[0006] However, the above-mentioned conventional cyclic olefin copolymers have room for further improvement in terms of achieving both a high refractive index and a low Abbe number.

[0007] Therefore, an object of the present invention is to provide a cyclic olefin copolymer having both a high refractive index and a low Abbe number, a resin composition that can be advantageously used as a material for various molded articles such as optical elements, and a molded article formed using the resin composition.

[0008] The present inventors have conducted extensive research to solve the above problems, and have found that a cyclic olefin copolymer containing predetermined structural units (A) to (C) and having a value obtained by dividing the total number of aromatic rings by the total number of all repeating units of at least a predetermined value can achieve both a high refractive index and a low Abbe number, thereby completing the present invention.

[0009] That is, the present invention aims to advantageously solve the above-mentioned problems, and provides the following cyclic olefin copolymers [1] to [4], the following resin composition [5], and the following molded articles [6] to [7].

[0010] [1] A cyclic olefin copolymer comprising a structural unit (A) derived from an α-olefin having from 2 to 10 carbon atoms, a structural unit (B) derived from a cyclic olefin, and a structural unit (C) derived from an aromatic vinyl compound, wherein the value obtained by dividing the total number of aromatic rings contained in the cyclic olefin copolymer by the total number of repeating units in the cyclic olefin copolymer is 0.25 or greater. In the present invention, the "value obtained by dividing the total number of aromatic rings contained in the cyclic olefin copolymer by the total number of repeating units in the cyclic olefin copolymer" (hereinafter sometimes abbreviated as "number of aromatic rings per number of repeating units") can be determined using the method described in the Examples of this specification. In the present invention, the term "aromatic ring" refers to an aromatic hydrocarbon ring such as a benzene ring, and does not include heteroaromatic rings. Furthermore, in the present invention, for a fused ring formed by the condensation of multiple benzene rings, such as a naphthalene ring or an anthracene ring, the number of benzene rings used in forming the condensation is defined as the "number of aromatic rings." Thus, for example, a naphthalene ring has two aromatic rings, and an anthracene ring has three aromatic rings.

[0011] [2] The cyclic olefin copolymer according to [1] above, having an Abbe number of 20 or more and 40 or less. In the present invention, the "Abbe number" can be measured using the method described in the examples of this specification.

[0012] [3] The cyclic olefin copolymer according to [1] or [2] above, wherein the structural unit (B) has at least one aromatic ring.

[0013] [4] The cyclic olefin copolymer according to any one of [1] to [3] above, wherein the value obtained by dividing the total number of aromatic rings contained in the cyclic olefin copolymer by the total number of repeating units in the cyclic olefin copolymer is 0.45 or more.

[0014] [5] A resin composition comprising the cyclic olefin copolymer according to any one of [1] to [4] above.

[0015] [6] A molded article obtained by molding the resin composition according to [5] above.

[0016] [7] The molded article according to [6] above, which is an optical lens. A resin composition containing a cyclic olefin copolymer having a high refractive index and a low Abbe number can be suitably used to form optical elements such as optical lenses.

[0017] According to the present invention, it is possible to provide a cyclic olefin copolymer having both a high refractive index and a low Abbe number. Furthermore, according to the present invention, it is possible to provide a resin composition that can be advantageously used as a material for various molded articles such as optical elements, and a molded article formed using the resin composition.

[0018] Hereinafter, embodiments of the present invention will be described in detail. Here, the cyclic olefin copolymer of the present invention can be used to prepare the resin composition of the present invention. The resin composition of the present invention can be used to form a molded article such as an optical lens. Furthermore, the molded article of the present invention is formed using the resin composition of the present invention.

[0019] (Cyclic Olefin Copolymer) The cyclic olefin polymer of the present invention contains structural units (A) to (C) and may optionally further contain structural units (other structural units) other than the structural units (A) to (C). The cyclic olefin copolymer of the present invention is characterized in that the number of aromatic rings per number of repeating units is 0.25 or more.

[0020] The cyclic olefin polymer of the present invention may be, for example, a random copolymer, a block copolymer, etc., as long as it contains the structural units (A) to (C). From the viewpoint of further increasing the refractive index while further decreasing the Abbe number, the cyclic olefin copolymer of the present invention is preferably a random copolymer.

[0021] <Structural Unit (A)> The structural unit (A) is a repeating unit derived from an α-olefin having from 2 to 10 carbon atoms. The α-olefin having from 2 to 10 carbon atoms that can form the structural unit (A) is not particularly limited, and examples thereof include ethylene (2 carbon atoms), propylene (3 carbon atoms), 1-butene (4 carbon atoms), 1-pentene (5 carbon atoms), 1-hexene (6 carbon atoms), 3-methyl-1-butene (5 carbon atoms), 3-methyl-1-pentene (6 carbon atoms), 3-ethyl-1-pentene (7 carbon atoms), 4-methyl-1-pentene (6 carbon atoms), 4-methyl-1-hexene (7 carbon atoms), 4,4-dimethyl-1-hexene (8 carbon atoms), 4,4-dimethyl-1-pentene (7 carbon atoms), 4-ethyl-1-hexene (8 carbon atoms), 3-ethyl-1-hexene (8 carbon atoms), 1-octene (8 carbon atoms), and 1-decene (10 carbon atoms). Among these, from the viewpoint of ensuring favorable ease of polymerization of the cyclic olefin copolymer, α-olefins having 2 to 4 carbon atoms are preferred, α-olefins having 2 to 3 carbon atoms are more preferred, and ethylene is even more preferred. The α-olefins having 2 to 10 carbon atoms may be used alone or in combination of two or more.

[0022] The content of the structural unit (A) in the cyclic olefin copolymer is preferably 30 mol% or more, more preferably 35 mol% or more, and is preferably 85 mol% or less, more preferably 70 mol% or less, even more preferably 60 mol% or less, and particularly preferably less than 50 mol%. If the content of the structural unit (A) is within the above range, the refractive index of the cyclic olefin copolymer can be further increased while the Abbe number can be further reduced.

[0023] <Structural Unit (B)> The structural unit (B) is a repeating unit derived from a cyclic olefin. The cyclic olefin capable of forming the structural unit (B) is not particularly limited, and examples thereof include norbornene compounds; cycloalkenes; non-norbornene compounds having an aromatic ring such as acenaphthylene, cyclopentabyrene, 1H-cyclopenta[l]phenanthrene, and 2-methylcyclopenta[l]phenanthrene (compounds having an aromatic ring in the molecule but not having a norbornene ring); and the like. Among these, norbornene compounds are preferably used from the viewpoint of further increasing the refractive index of the cyclic olefin copolymer while further reducing the Abbe number. Note that the cyclic olefin may be used alone or in combination of two or more.

[0024] Norbornene compounds are broadly classified into norbornene compounds having an aromatic ring (compounds having a norbornene ring and an aromatic ring in the molecule) and norbornene compounds not having an aromatic ring (compounds having a norbornene ring in the molecule but not an aromatic ring).

[0025] Examples of norbornene compounds having an aromatic ring include phenylnorbornenes such as 5-phenyl-2-norbornene; naphthylnorbornenes such as 1-naphthylnorbornene and 2-naphthylnorbornene; 5-methyl-5-phenyl-bicyclo[2.2.1]hept-2-ene, 5-benzyl-bicyclo[2.2.1]hept-2-ene, 5-tolyl-bicyclo[2.2.1]hept-2-ene [i.e., 5-(4-methylphenyl)-2-norbornene], 5-(ethylphenyl)-bicyclo[2.2.1]hept-2-ene, 5-(isopropylphenyl)-bicyclo[2.2.1]hept-2-ene, 5-methyl-5-carboxybenzylbicyclo[2.2.1]hept-2-ene, 8-phenyl-tetracyclo[4.4.0 ... ２，５ .1 ７，１０ ]-3-dodecene, 8-methyl-8-phenyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 8-benzyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０]-3-dodecene, 8-tolyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 8-(ethylphenyl)-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 8-(isopropylphenyl)-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 8,9-diphenyl-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 8-(biphenyl)-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 8-(β-naphthyl)-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 8-(α-naphthyl)-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 8-(anthracenyl)-tetracyclo[4.4.0.1 ２，５ .1 ７，１０ ]-3-dodecene, 11-phenyl-hexacyclo[6.6.1.1 ３，６ .1 １０，１３ .0 ２，７ .0 ９，１４]-4-heptadecene, 6-(α-naphthyl)-bicyclo[2.2.1]-hept-2-ene, 5-(anthracenyl)-bicyclo[2.2.1]-hept-2-ene, 5-(biphenyl)-bicyclo[2.2.1]-hept-2-ene, 5-(β-naphthyl)-bicyclo[2.2.1]-hept-2-ene, 5,6-diphenyl-bicyclo[2.2. 1]-hept-2-ene, 9-(2-norbornen-5-yl)-carbazole, 1,4-methano-1,4,4a,4b,5,8,8a,9a-octahydrofluorene, 1,4-methano-1,4,4a,9a-tetrahydrofluorene, 1,4-methano-8-methyl-1,4,4a,9a-tetrahydrofluorene, 1,4-methano-8-chloro-1 , 4,4a,9a-tetrahydrofluorene, 1,4-methano-8-bromo-1,4,4a,9a-tetrahydrofluorene, 1,4-methano-1,4,4a,9a-tetrahydrodibenzofuran, 1,4-methano-1,4,4a,9a-tetrahydrocarbazole, 1,4-methano-9-phenyl-1,4,4a,9a-tetrahydrocarbazole, 1,4-methano-1,4,4a,5,10,10a-hexahydroanthracene, 7,10-methano-6b,7,10,10a-tetrahydrofluoranthene, cyclopentadiene-acenaphthylene adduct, compounds in which cyclopentadiene is further added to the cyclopentadiene-acenaphthylene adduct, 11,12-benzo-pentacyclo[6.5.1.1 ３，６ .0 ２，７ .0 ９，１３ ]-4-pentadecene, 11,12-benzo-pentacyclo[6.6.1.1 ３，６ .0 ２，７ .0 ９，１４ ]-4-hexadecene, 14,15-benzo-heptacyclo[8.7.0.1 ２，９ .1 ４，７ .1 １１，１７ .0 ３，８ .0 １２，１６]-5-eicosene, 5,5a,6,9,9a,10,10a,11-octahydro-4bH-5,10; 6,9-dimethano-benzo[b]fluorene, and derivatives thereof. The derivative refers to a compound having a substituent in the ring structure. The substituent that can be contained in the ring structure is not particularly limited, and examples thereof include an alkyl group, an alkylene group, a vinyl group, an alkoxycarbonyl group, and an alkylidene group. The ring structure of the derivative may have one or more of these substituents.

[0026] Furthermore, examples of norbornene compounds that do not have an aromatic ring include tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene (trivial name: tetracyclododecene), 2-ethylidene-1,2,3,4,4a,5,8,8a-octahydro-1,4:5,8-dimethanonaphthalene (trivial name: ethylidenetetracyclododecene), tricyclo[5.2.1.0 ２，６ ]deca-3,8-diene (trivial name: dicyclopentadiene), 5-ethylidenebicyclo[2.2.1]hept-2-ene (trivial name: ethylidenenorbornene), bicyclo[2.2.1]hept-2-ene (also called "norbornene"), 5-ethyl-bicyclo[2.2.1]hept-2-ene, 5-butyl-bicyclo[2.2.1]hept-2-ene, 5-methylidene-bicyclo[2.2.1]hept-2-ene, 5-vinyl-bicyclo[2.2.1]hept-2-ene, tetracyclo[10.2.1.0 ２，１１ .0 ４，９ ] pentadeca-4,6,8,13-tetraene, 9-methyl-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-ethyl-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-methylidene-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-ethylidene-tetracyclo[6.2.1.1 ３，６ .0 ２，７] dodec-4-ene, 1,2,3,3a,4,6a-hexahydro-1,2,4-methenopentalene, 9-vinyl-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-propenyl-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, pentacyclo[9.2.1.1 ３，９ .0 ２，１０ .0 ４，８ ] pentadeca-5,12-diene, tetracyclo[9.2.1.0 ２，１０ .0 ３，８ ] tetradeca-3,5,7,12-tetraene, pentacyclo[9.2.1.1 ３，９ .0 ２，１０ .0 ４，８ ]pentadec-12-ene, and derivatives thereof.

[0027] Among the above, from the viewpoint of further increasing the refractive index of the cyclic olefin copolymer while further decreasing the Abbe number, norbornene compounds having an aromatic ring are preferred, and 1,4-methano-1,4,4a,9a-tetrahydrofluorene, 5,5a,6,9,9a,10,10a,11-octahydro-4bH-5,10;6,9-dimethano-benzo[b]fluorene are more preferred.

[0028] Here, from the viewpoint of further increasing the refractive index of the cyclic olefin copolymer and further decreasing the Abbe number, it is preferable that the structural unit (B) has at least one aromatic ring. Examples of the cyclic olefin that can form the structural unit (B) having an aromatic ring include the above-mentioned norbornene compounds having an aromatic ring. The upper limit of the number of aromatic rings that the structural unit (B) has is not particularly limited, and can be, for example, 5 or less, or 3 or less.

[0029] The content of the structural unit (B) in the cyclic olefin copolymer is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, and is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less. If the content of the structural unit (B) is within the above range, the refractive index of the cyclic olefin copolymer can be further increased while the Abbe number can be further reduced.

[0030] <Structural Unit (C)> The structural unit (C) is a repeating unit derived from an aromatic vinyl compound. The aromatic vinyl compound capable of forming the structural unit (C) is not particularly limited, and examples thereof include aromatic vinyl compounds having one aromatic ring such as styrene, styrenesulfonic acid and its salts, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, p-t-butylstyrene, 5-t-butyl-2-methylstyrene, butoxystyrene, 4-methoxystyrene, vinyltoluene, and chlorostyrene; aromatic vinyl compounds having two aromatic rings such as 1-vinylnaphthalene, 2-vinylnaphthalene, 4-vinylbiphenyl, 2-vinylfluorene, and 9-vinylfluorene; and compounds having three aromatic rings such as 1-vinylanthracene, 2-vinylanthracene, 9-vinylanthracene, 1-ethenylphenanthrene, 2-ethenylphenanthrene, 3-ethenylphenanthrene, 4-ethenylphenanthrene, and 9-ethenylphenanthrene. Among these, aromatic vinyl compounds having 1 to 3 aromatic rings are preferred, aromatic vinyl compounds having 1 to 2 aromatic rings are more preferred, styrene, 2-vinylnaphthalene, and 4-vinylbiphenyl are even more preferred, and 2-vinylnaphthalene and 4-vinylbiphenyl are particularly preferred. The aromatic vinyl compounds may be used alone or in combination of two or more.

[0031] The content of the structural unit (C) in the cyclic olefin copolymer is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, and is preferably 50 mol% or less, and more preferably 45 mol% or less. If the content of the structural unit (C) is within the above range, the refractive index of the cyclic olefin copolymer can be further increased while the Abbe number can be further reduced.

[0032] <Other structural units> The other compounds capable of forming the other structural units are not particularly limited, and examples thereof include compounds copolymerizable with the above-mentioned compounds. Note that the other compounds may be used alone or in combination of two or more.

[0033] The content of other structural units in the cyclic olefin copolymer is usually less than 20 mol%, preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and particularly preferably 0 mol% (i.e., the cyclic olefin copolymer does not contain other structural units).

[0034] <Properties> [Weight-average molecular weight] The cyclic olefin polymer of the present invention preferably has a weight-average molecular weight of 10,000 or more, more preferably 15,000 or more, even more preferably 17,500 or more, particularly preferably 20,000 or more, and preferably 200,000 or less, more preferably 100,000 or less, and even more preferably 70,000 or less. If the weight-average molecular weight of the cyclic olefin polymer is 10,000 or more, a decrease in the strength of a molded article obtained using the cyclic olefin polymer can be suppressed. On the other hand, if the weight-average molecular weight of the cyclic olefin polymer is 200,000 or less, the occurrence of molding defects due to deterioration of fluidity during molding of the cyclic olefin polymer can be suppressed.

[0035] In the present invention, the weight average molecular weight can be measured by the method described in the examples of this specification.

[0036] [Glass transition temperature] The cyclic olefin polymer of the present invention preferably has a glass transition temperature of 50°C or higher, more preferably 80°C or higher, and even more preferably 110°C or higher, and preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. If the glass transition temperature of the cyclic olefin polymer is 50°C or higher, it is possible to prevent deterioration of heat resistance and deterioration of optical properties due to thermal deformation and the like. On the other hand, if the glass transition temperature of the cyclic olefin polymer is 200°C or lower, it is possible to prevent oxidative degradation of the cyclic olefin polymer caused by excessively high processing temperatures when molding the cyclic olefin polymer. The "glass transition temperature" can be measured, for example, according to JIS K7121.

[0037] [Abbe Number] The cyclic olefin polymer of the present invention preferably has an Abbe number of 15 or more, more preferably 20 or more, and preferably 40 or less, more preferably 35 or less. When the Abbe number is within the above range, a high-performance lens module can be designed.

[0038] [Number of aromatic rings per repeating unit] Here, the value obtained by dividing the total number of aromatic rings contained in the cyclic olefin copolymer by the total number of repeating units in the cyclic olefin copolymer (number of aromatic rings per repeating unit) must be 0.25 or more. If the number of aromatic rings per repeating unit is less than 0.25, the refractive index decreases and the Abbe number increases. The number of aromatic rings per repeating unit is preferably 0.45 or more, more preferably 0.55 or more, and even more preferably 0.65 or more. If the number of aromatic rings per repeating unit is 0.45 or more, the refractive index of the cyclic olefin copolymer can be further increased while the Abbe number can be further reduced. The upper limit of the number of aromatic rings per repeating unit is not particularly limited, and can be, for example, 2.00 or less, or 1.50 or less.

[0039] <Method for Preparing Cyclic Olefin-Based Copolymer> The method for preparing the cyclic olefin-based copolymer is not particularly limited, and for example, the cyclic olefin-based copolymer can be produced by copolymerizing (addition polymerizing) a monomer composition containing the above-mentioned α-olefin having from 2 to 10 carbon atoms, a cyclic olefin, and an aromatic vinyl compound, and optionally containing other compounds, in a hydrocarbon solvent in the presence of a catalyst. Examples of such a method include those described in JP 2016-155327 A and JP 2020-079357 A.

[0040] (Resin composition) The resin composition of the present invention contains the above-mentioned cyclic olefin copolymer of the present invention, and optionally further contains polymer materials other than the cyclic olefin copolymer of the present invention and various additives. Since the resin composition of the present invention contains the cyclic olefin copolymer of the present invention, which has both a high refractive index and a low Abbe number, it can be particularly advantageously used as a material for various molded articles such as optical elements.

[0041] The polymeric materials and additives that can be contained in the resin composition are not particularly limited, and examples thereof include the polymeric materials and additives described in Japanese Patent Application Laid-Open No. 10-139865.

[0042] The polymeric material and the additives are not particularly limited as long as they can be sufficiently dispersed in the cyclic olefin copolymer, and can be mixed with the cyclic olefin copolymer using any method. Specifically, the polymeric material and the additives may be added in any step during the preparation of the cyclic olefin copolymer, or may be kneaded with the cyclic olefin copolymer using a kneader, or may be mixed with the cyclic olefin copolymer in a molding device.

[0043] (Molded Article) The molded article of the present invention is formed using the resin composition of the present invention and contains the cyclic olefin copolymer of the present invention, and therefore can exhibit excellent performance.

[0044] Here, examples of molding methods that can be used include injection molding, extrusion blow molding, injection blow molding, two-stage blow molding, multi-layer blow molding, connection blow molding, stretch blow molding, rotational molding, vacuum molding, extrusion molding, calendar molding, solution casting, hot press molding, and inflation molding.

[0045] Among these, the molded article of the present invention is preferably a lens, and more preferably an optical lens. The lens is not particularly limited and can be obtained, for example, by uniformly heating and melting the resin composition of the present invention to form a preform, then heating and stretching the preform, and thereafter, if necessary, heat setting.

[0046] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified. In the examples and comparative examples, various measurements and evaluations were performed by the following methods.

[0047] (1) Weight-average molecular weight The weight-average molecular weight (Mw) of the cyclic olefin copolymer was measured by gel permeation chromatography (manufactured by Tosoh Corporation, product name "HLC-8320"). The weight-average molecular weight (Mw) of the cyclic olefin copolymer obtained in the examples and comparative examples other than Comparative Example 2 was determined as a polystyrene equivalent value using three columns (TSKgel (registered trademark) Super H2000, TSKgel Super H4000, and TSKgel Super H5000) manufactured by Tosoh Corporation connected in series and tetrahydrofuran as the developing solvent. The weight average molecular weight (Mw) of the cyclic olefin copolymer obtained in Comparative Example 2 was determined as a polyisoprene equivalent value using three columns (TSKgel G2000HXL, TSKgel G4000HXL, and TSKgel G5000HXL) manufactured by Tosoh Corporation connected in series and cyclohexane as a developing solvent. １ H and １３The C-NMR (nuclear magnetic resonance) spectrum was measured, and the content (mol %) of the structural units (A) to (C) in the polymer was determined using the integral values ​​of the signals derived from each of the structural units (A) to (C). Then, the "number of aromatic rings per number of repeating units" was calculated according to the following formula (1). In formula (1), a: content (mol%) of structural unit (A), b: content (mol%) of structural unit (B), c: content (mol%) of structural unit (C), x: number of aromatic rings possessed by the monomer capable of forming structural unit (B), y: number of aromatic rings possessed by the monomer capable of forming structural unit (C), where a + b + c = 100. (3) Refractive Index The cyclic olefin copolymers prepared in the examples and comparative examples were molded into sheets by hot pressing to serve as measurement samples. The refractive index of the obtained measurement samples at 25°C and a wavelength of 589.3 nm was measured using a refractometer (manufactured by Anton Paar, product name "ABBEMAT-WR / MW"). (4) Abbe number In the above "(3) Refractive index", when measuring the refractive index at a wavelength of 589.3 nm, the refractive index (nd) at a wavelength of 587.6 nm, the refractive index (nC) at a wavelength of 656.3 nm, and the refractive index (nF) at a wavelength of 486.1 nm were also measured. Then, the Abbe number (νd) was calculated according to the following formula (2) using the refractive indices (nd, nC, nF) at a temperature of 25° C.

[0048] Example 1 Preparation of Cyclic Olefin Copolymer 10 g of toluene, 2.5 g of 1,4-methano-1,4,4a,9a-tetrahydrofluorene (MTF) as monomer (b), 7.5 g of styrene as monomer (c), and 3.0 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure reactor and stirred. The entire contents were then added to another 100 mL glass pressure reactor containing a stirrer and 40 mg of rac-ethylenebis(indenyl)zirconium(IV) dichloride to initiate the polymerization reaction. During the polymerization reaction, ethylene gas as monomer (a) was introduced to a pressure of 0.15 MPa, and the mixture was stirred at 1000 rpm. After the reaction was allowed to proceed for 15 minutes at 25°C, the pressure was released and the polymerization reaction was terminated by adding 2-propanol dropwise. The contents of the glass pressure reactor were then transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was then filtered, washed, and dried under reduced pressure at 70°C for 15 hours to obtain a cyclic olefin copolymer. The weight average molecular weight, the number of aromatic rings per repeating unit, the refractive index, and the Abbe number of this cyclic olefin copolymer were then measured. The results are shown in Table 1.

[0049] Example 2 Various measurements were performed in the same manner as in Example 1, except that a cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of Cyclic Olefin Copolymer> 10.0 g of MTF, 10.0 g of styrene, and 1.5 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure reactor and stirred. The entire amount was then added to another 100 mL glass pressure reactor containing a stirrer and 40 mg of rac-ethylenebis(indenyl)zirconium(IV) dichloride to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and the mixture was stirred at 1,000 rpm. After the reaction was carried out at 25°C for 30 minutes, the pressure was released and the polymerization reaction was terminated by adding 2-propanol dropwise. The contents of the glass pressure reactor were then transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was then filtered, washed, and dried under reduced pressure at 70° C. for 15 hours to obtain a cyclic olefin copolymer.

[0050] Example 3 Various measurements were performed in the same manner as in Example 1, except that a cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of Cyclic Olefin Copolymer> 1.4 g of toluene, 5.2 g of MTF, 5.2 g of 2-vinylnaphthalene, and 6.2 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure reactor and stirred. The entire contents were then added to another 100 mL glass pressure reactor containing a stirrer and 40 mg of rac-ethylenebis(indenyl)zirconium(IV) dichloride to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and the mixture was stirred at 1,000 rpm. After the reaction was carried out at 25°C for 30 minutes, the pressure was released and the polymerization reaction was terminated by dropwise addition of 2-propanol. The contents of the glass pressure reactor were then transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was then filtered, washed, and dried under reduced pressure at 70° C. for 15 hours to obtain a cyclic olefin copolymer.

[0051] Example 4 Various measurements were performed in the same manner as in Example 1, except that a cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of Cyclic Olefin Copolymer> 12.8 g of MTF, 3.2 g of 2-vinylnaphthalene, and 7.3 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure reactor and stirred, and then the entire amount was added to another 100 mL glass pressure reactor containing a stirrer and 49 mg of rac-ethylenebis(indenyl)zirconium(IV) dichloride to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and stirring was carried out at 1000 rpm. After the reaction was carried out at 25°C for 60 minutes, the pressure was released and the polymerization reaction was terminated by dropwise addition of 2-propanol. The contents of the glass pressure reactor were then transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was then filtered, washed, and dried under reduced pressure at 70° C. for 15 hours to obtain a cyclic olefin copolymer.

[0052] Example 5 Various measurements were carried out in the same manner as in Example 1, except that a cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of Cyclic Olefin Copolymer> 12.8 g of MTF, 3.2 g of 2-vinylnaphthalene, and 7.3 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure reactor and stirred, and then the entire amount was added to another 100 mL glass pressure reactor containing a stirrer and 45 mg of [2,6-bis(1-methylethyl)phenolate]dichloro[(1,2,3,4,5-η)-1,3-dimethyl-2,4-cyclopentadien-1-yl]titanium to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and the mixture was stirred at 1,000 rpm. After reacting for 60 minutes at 25°C, the pressure was released and 2-propanol was added dropwise to terminate the polymerization reaction. Next, the contents of the glass pressure reactor were transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was then filtered, washed, and dried under reduced pressure at 70°C for 15 hours to obtain a cyclic olefin copolymer.

[0053] Example 6 Various measurements were performed in the same manner as in Example 1, except that a cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of Cyclic Olefin Copolymer> 22.7 g of toluene, 5.9 g of 5,5a,6,9,9a,10,10a,11-octahydro-4bH-5,10;6,9-dimethano-benzo[b]fluorene (HNT), 5.9 g of 2-vinylnaphthalene, and 17.0 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure-resistant reactor and stirred. The entire amount was then added to another 100 mL glass pressure-resistant reactor containing a stirrer and 120 mg of rac-ethylenebis(indenyl)zirconium(IV) dichloride to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and the mixture was stirred at 1000 rpm. After reacting for 70 minutes at 25°C, the pressure was released and 2-propanol was added dropwise to terminate the polymerization reaction. Next, the contents of the glass pressure reactor were transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was filtered, washed, and then dried under reduced pressure at 70°C for 15 hours to obtain a cyclic olefin copolymer.

[0054] Example 7 Various measurements were performed in the same manner as in Example 1, except that a cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of Cyclic Olefin Copolymer> 10.2 g of toluene, 3.0 g of MTF, 3.0 g of 4-vinylbiphenyl, and 3.1 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure reactor and stirred. The entire contents were then added to another 100 mL glass pressure reactor containing a stirrer and 44 mg of rac-ethylenebis(indenyl)zirconium(IV) dichloride to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and the mixture was stirred at 1,000 rpm. After the reaction was allowed to proceed at 25°C for 15 minutes, the pressure was released and 2-propanol was added dropwise to terminate the polymerization reaction. The contents of the glass pressure reactor were then transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was then filtered, washed, and dried under reduced pressure at 70° C. for 15 hours to obtain a cyclic olefin copolymer.

[0055] Example 8 Various measurements were carried out in the same manner as in Example 1, except that a cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of Cyclic Olefin Copolymer> 5.9 g of toluene, 11.5 g of MTF, 2.6 g of 4-vinylbiphenyl, and 10.9 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure reactor and stirred, and then the entire amount was added to another 100 mL glass pressure reactor containing a stirrer and 69 mg of [2,6-bis(1-methylethyl)phenolate]dichloro[(1,2,3,4,5-η)-1,3-dimethyl-2,4-cyclopentadien-1-yl]titanium to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and the mixture was stirred at 1,000 rpm. After reacting for 60 minutes at 25°C, the pressure was released and 2-propanol was added dropwise to terminate the polymerization reaction. Next, the contents of the glass pressure reactor were transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was then filtered, washed, and dried under reduced pressure at 70°C for 15 hours to obtain a cyclic olefin copolymer.

[0056] Comparative Example 1 Various measurements were performed in the same manner as in Example 1, except that a cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of Cyclic Olefin Copolymer> 15.1 g of toluene, 2.0 g of MTF, 2.0 g of styrene, and 0.8 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were placed in a nitrogen-purged 100 mL glass pressure reactor and stirred, and then the entire amount was added to another 100 mL glass pressure reactor containing a stirrer and 42 mg of rac-ethylenebis(indenyl)zirconium(IV) dichloride to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and stirring was carried out at 1000 rpm. After the reaction at 25°C for 30 minutes, the pressure was released and the polymerization reaction was terminated by dropwise addition of 2-propanol. The contents of the glass pressure reactor were then transferred into a large amount of 2-propanol acidified with hydrochloric acid to precipitate a polymer, which was then filtered, washed, and dried under reduced pressure at 70° C. for 15 hours to obtain a cyclic olefin copolymer.

[0057] (Comparative Example 2) Various measurements were carried out in the same manner as in Example 1, except that the cyclic olefin copolymer prepared as follows was used. The results are shown in Table 1. <Preparation of cyclic olefin copolymer> 5.1 g of toluene, tetracyclo[6.2.1.1], and 100 mL of toluene were added to a 100 mL glass pressure reactor purged with nitrogen. ３，６ .0 ２，７ 10.2 g of ] dodec-4-ene (TCD), 5.2 g of styrene, and 6.5 g of a cyclohexane solution of solid methylaluminoxane (Al concentration = 14.8%) were added and stirred, and then the entire amount was added to another 100 mL glass pressure reactor containing a stirrer and 40 mg of rac-ethylenebis(indenyl)zirconium(IV) dichloride to initiate the polymerization reaction. During the polymerization reaction, ethylene gas was introduced to a pressure of 0.15 MPa, and the mixture was stirred at 1000 rpm. After reacting for 15 minutes at 25°C, the pressure was reduced and the polymerization reaction was terminated by the dropwise addition of 2-propanol. The contents of the glass pressure reactor were then transferred to a large amount of hydrochloric acid-acidified 2-propanol, and the polymer was precipitated. After filtration and washing, the polymer was dried under reduced pressure at 70°C for 15 hours to obtain a cyclic olefin copolymer.

[0058] In Table 1 below, "MTF" represents a structural unit derived from 1,4-methano-1,4,4a,9a-tetrahydrofluorene, "HNT" represents a structural unit derived from 5,5a,6,9,9a,10,10a,11-octahydro-4bH-5,10;6,9-dimethano-benzo[b]fluorene, and "TCD" represents a structural unit derived from tetracyclo[6.2.1.1]fluorene. ３，６ .0 ２，７ ] represents a structural unit derived from dodec-4-ene, "ST" represents a structural unit derived from styrene, "2-VN" represents a structural unit derived from 2-vinylnaphthalene, "4-VB" represents a structural unit derived from 4-vinylbiphenyl, and "Mw" represents the weight average molecular weight.

[0059]

[0060] According to the present invention, it is possible to provide a cyclic olefin copolymer having both a high refractive index and a low Abbe number. Furthermore, according to the present invention, it is possible to provide a resin composition that can be advantageously used as a material for various molded articles such as optical elements, and a molded article formed using the resin composition.

Claims

1. A cyclic olefin copolymer comprising: structural units (A) derived from an α-olefin having from 2 to 10 carbon atoms; structural units (B) derived from a cyclic olefin; and structural units (C) derived from an aromatic vinyl compound, wherein the value obtained by dividing the total number of aromatic rings contained in the cyclic olefin copolymer by the total number of repeating units in the cyclic olefin copolymer is 0.25 or more.

2. The cyclic olefin copolymer according to claim 1, having an Abbe number of 20 or more and 40 or less.

3. The cyclic olefin copolymer according to claim 1, wherein the structural unit (B) has at least one aromatic ring.

4. The cyclic olefin copolymer according to claim 1, wherein the value obtained by dividing the total number of aromatic rings contained in the cyclic olefin copolymer by the total number of repeating units in the cyclic olefin copolymer is 0.45 or more.

5. A resin composition comprising the cyclic olefin copolymer according to any one of claims 1 to 4.

6. A molded article obtained by molding the resin composition according to claim 5.

7. The molded article according to claim 6, which is an optical lens.

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