JP7798593B2 - Resin composition for press molding and press-molded article - Google Patents

Description

The present invention relates to a press-molding resin composition containing a cyclic olefin copolymer, and a press-molded article.

Cyclic olefin polymers and cyclic olefin copolymers (also referred to as "COP" and "COC," respectively) have low moisture absorption and high transparency. For this reason, COPs and COCs are used in a variety of applications, including optical materials such as optical disc substrates, optical films, and optical fibers. A typical COC is a copolymer of cyclic olefin and ethylene. The glass transition temperature of such a copolymer can be changed by the copolymerization composition of the cyclic olefin and ethylene. Therefore, copolymers of cyclic olefin and ethylene can be produced as copolymers with a higher glass transition temperature (Tg) than COPs, and it is possible to achieve a Tg of over 200°C, which is difficult to achieve with COPs. However, such copolymers are hard and brittle. As a result, such copolymers have problems such as low mechanical strength and poor handleability and processability.

One method for improving the mechanical strength of high Tg COC is to copolymerize a cyclic olefin with an α-olefin other than ethylene (hereinafter referred to as a "specific α-olefin"). Various studies have been conducted on the copolymerization of cyclic olefins with specific α-olefins.

The copolymerization of cyclic olefins and specific α-olefins is significantly different from the copolymerization of cyclic olefins and ethylene. Under conditions that produce high molecular weight polymers in the copolymerization of cyclic olefins and ethylene, chain transfer reactions caused by the specific α-olefin occur in the copolymerization of cyclic olefins and specific α-olefins, making it difficult to obtain high molecular weight polymers. Therefore, copolymers of cyclic olefins and specific α-olefins have been considered unsuitable for use as molding materials (see, for example, Non-Patent Document 1).

For this reason, various studies have been conducted to improve the moldability of copolymers of cyclic olefins and specific α-olefins. For example, a method has been proposed for producing copolymers of cyclic olefins and specific α-olefins that have a relatively high molecular weight and can be molded into films, in which the cyclic olefin and the specific α-olefin are copolymerized in the presence of a titanocene catalyst with a specific structure and triphenylmethylium tetrakis(pentafluorophenyl)borate (see Patent Document 1).

JP 2016-56275 A

Jung, H. Y. et al., Polyhedron, 2005, Vol. 24, pp. 1269-1273

However, even when press molding is performed using a copolymer of a cyclic olefin and a specific α-olefin obtained by the method described in Patent Document 1, there are problems such as the failure to obtain a press-molded article that combines excellent fracture strain and toughness, and the resulting press-molded article being prone to discoloration.

The present invention was made in consideration of the above circumstances, and aims to provide a press-molding resin composition containing a cyclic olefin copolymer that combines excellent breaking strain and excellent toughness and produces press-molded articles with little coloration, as well as a press-molded article made from the press-molding resin composition.

The inventors have discovered that the above-mentioned problems can be solved by providing a press-molding resin composition containing (A) a cyclic olefin copolymer and a specific amount of (B) a hindered phenol-based antioxidant, using as the (A) cyclic olefin copolymer a copolymer of a cyclic olefin monomer and an α-olefin having from 3 to 20 carbon atoms, setting the amount of structural units derived from the α-olefin in the (A) cyclic olefin copolymer to from 10 mol % to 40 mol % of all structural units, and ensuring that the (A) cyclic olefin copolymer has two or more glass transition temperatures within the range of 0°C to 300°C as determined by solid viscoelasticity measurement, and thereby completing the present invention. More specifically, the present invention provides the following.

(I) A press-molding resin composition comprising (A) a cyclic olefin copolymer and (B) a hindered phenol-based antioxidant,
(A) The cyclic olefin copolymer is an addition polymer of a cyclic olefin monomer and an α-olefin having 3 to 20 carbon atoms,
(A) the ratio of the number of moles of structural units derived from an α-olefin to the number of moles of all structural units of the cyclic olefin copolymer is 10 mol % or more and 40 mol % or less,
(A) the cyclic olefin copolymer has two or more glass transition temperatures determined by viscoelasticity measurement within a range of 0°C to 300°C;
The press-molding resin composition has a content of the hindered phenol-based antioxidant (B) of 0.1 to 2.0 parts by mass per 100 parts by mass of the cyclic olefin copolymer (A).

(II) The press-molding resin composition described in (I), wherein (A) the cyclic olefin copolymer has at least one glass transition temperature within the range of 0°C to 100°C and at least one glass transition temperature within the range of 160°C to 300°C.

(III) A press-molding resin composition according to (I) or (II), in which the cyclic olefin copolymer (A) has at least one glass transition temperature below 0°C, at least one glass transition temperature between 0°C and 100°C, and at least one glass transition temperature between 160°C and 300°C.

(VI) A press-molded article made from the press-molding resin composition described in any one of (I) to (III).

(V) The press-molded body according to (IV), having a relative dielectric constant of 2.2 or less and a dielectric dissipation factor of 3.0 × 10 ^or less at a measurement frequency of 40 GHz.

The present invention provides a press-molding resin composition containing a cyclic olefin copolymer that combines excellent breaking strain and excellent toughness and produces press-molded articles with little coloration, as well as a press-molded article made from the press-molding resin composition.

Embodiments of the present invention are described in detail below. Note that the present invention is not limited to the following embodiments.

<Press molding resin composition>
The press-molding resin composition contains (A) a cyclic olefin copolymer and (B) a hindered phenol-based antioxidant.
The content of the hindered phenol-based antioxidant (B) in the press-molding resin composition is 0.1 to 2.0 parts by mass based on 100 parts by mass of the cyclic olefin copolymer (A).
By using the above-mentioned resin composition for press molding, it is possible to obtain a press-molded article that has both excellent breaking strain and excellent toughness and is less colored.

The essential and optional components contained in the press-molding resin composition are described below.

<(A) Cyclic Olefin Copolymer>
The (A) cyclic olefin copolymer is an addition polymer of a cyclic olefin monomer and an α-olefin having 3 to 20 carbon atoms. In the (A) cyclic olefin copolymer, the ratio of the number of moles of structural units derived from the α-olefin to the number of moles of all structural units is 10 mol % to 40 mol %. The (A) cyclic olefin copolymer also has two or more glass transition temperatures within the range of 0°C to 300°C as determined by viscoelasticity measurement.

Although the detailed mechanism is unknown, the cyclic olefin copolymer (A) has both excellent breaking strain and excellent toughness.
Specifically, the cyclic olefin copolymer (A) exhibits a tensile strength of preferably 25 MPa or more, more preferably 30 MPa or more, and even more preferably 40 MPa or more, as measured in a tensile test performed at 23°C using a No. 2 dumbbell test piece having a thickness of 50 μm according to a method in accordance with ISO 527-3.
Furthermore, the cyclic olefin copolymer (A) preferably exhibits a tensile strain at break of 3.5% or more, more preferably 5% or more, and even more preferably 10% or more, as measured by the tensile test according to the above method.
Furthermore, the cyclic olefin copolymer (A) preferably exhibits a tensile modulus of 1000 MPa or more, more preferably 1100 MPa or more, and even more preferably 1500 MPa or more, as measured by the tensile test according to the above method.

In the cyclic olefin copolymer (A), the ratio of the number of moles of structural units derived from an α-olefin to the number of moles of all structural units is 10 mol% or more and 40 mol% or less, and preferably 20 mol% or more and 30 mol% or less. If the ratio of the number of moles of structural units derived from an α-olefin is too high, it is difficult to obtain a cyclic olefin copolymer (A) having high tensile strength and tensile modulus. If the ratio of the number of moles of structural units derived from an α-olefin is too high, it is difficult to obtain a cyclic olefin copolymer (A) having a high glass transition temperature and excellent heat resistance.
The ratio of the number of moles of structural units derived from α-olefins can be calculated by measuring ¹³ C-NMR spectrum.

(A) The cyclic olefin copolymer may contain structural units other than structural units derived from cyclic olefin monomers and structural units derived from α-olefins having 3 to 20 carbon atoms, provided that the objectives of the present invention are not impaired. As the other structural units, structural units derived from compounds copolymerizable with cyclic olefin monomers and α-olefins having 3 to 20 carbon atoms and having a carbon-carbon unsaturated double bond may be used. Typically, structural units derived from ethylene are preferred as the other structural units.

In (A) the cyclic olefin copolymer, the sum of the ratio of the number of moles of structural units derived from cyclic olefin monomers and the ratio of the number of moles of structural units derived from α-olefins to the number of moles of all structural units is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and most preferably 100 mol%.

The cyclic olefin copolymer (A) has two or more glass transition temperatures within the range of 0°C to 300°C as determined by viscoelasticity measurement.
The glass transition temperature can be measured by using a film-like molded product having a thickness of 50 μm and observing the viscoelastic behavior with a solid rheometer at −100° C. to 300° C. Specifically, the glass transition temperature is determined as the peak top temperature in the tan δ chart obtained by the above-mentioned measurement.

The cyclic olefin copolymer (A) preferably has at least one glass transition temperature within the range of 0°C to 100°C and at least one glass transition temperature within the range of 160°C to 300°C, since the mechanical properties measured by the above tensile test are good.
In particular, since the breaking strain measured by the above-mentioned tensile test is large, it is preferable that the (A) cyclic olefin copolymer has at least one glass transition temperature in the range of less than 0°C, in the range of 0°C to 100°C, and in the range of 160°C to 300°C.
Within the above range of 0°C to 100°C, the range of 30°C to 80°C is preferred, and the range of 40°C to 70°C is more preferred.
Within the above range of 160°C to 300°C, 170°C to 280°C is preferred, and 180°C to 270°C is more preferred.
Within the above range of less than 0°C, -50°C to 0°C is preferred, and -40°C to -10°C is more preferred.

Typically, (A) the cyclic olefin copolymer has one glass transition temperature in the range of 0°C to 100°C and one glass transition temperature in the range of 160°C to 300°C, or one glass transition temperature in the range below 0°C, one glass transition temperature in the range of 0°C to 100°C, and one glass transition temperature in the range of 160°C to 300°C.

The molecular weight of the cyclic olefin copolymer (A) is not particularly limited. The weight average molecular weight (Mw) of the cyclic olefin copolymer (A) is preferably 5,000 or more and 200,000 or less, and more preferably 10,000 or more and 100,000 or less, as a polystyrene-equivalent value measured by gel permeation chromatography (GPC).
The number average molecular weight (Mn) of the cyclic olefin copolymer (A) is preferably 5,000 or more and 200,000 or less, more preferably 10,000 or more and 100,000 or less, in terms of polystyrene, measured by gel permeation chromatography (GPC).
The dispersion ratio (Mw/Mn) is preferably 1.2 or more, and more preferably 1.3 or more.

[Cyclic olefin monomer]
The cyclic olefin monomer is not particularly limited as long as it does not impair the object of the present invention. Typically, norbornene and substituted norbornene are preferably used as the cyclic olefin monomer. Norbornene is particularly preferred as the cyclic olefin monomer in terms of a good balance between cost, polymerizability, and the physical properties of the resulting cyclic olefin copolymer (A). The cyclic olefin monomer may be used alone or in combination of two or more.

The substituted norbornene is not particularly limited. Substituents on the substituted norbornene include, for example, halogen atoms and monovalent or divalent hydrocarbon groups. Specific examples of substituted norbornenes include compounds represented by formula (I) below.

In formula (I), R ^a1 to R ^a12 may be the same or different and each represents an atom or group selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group.
R ^a9 and R ^a10 , and R ^a11 and R ¹² may combine together to form a divalent hydrocarbon group.
R ^a9 or R ^a10 and R ^a11 or R ^a12 may be bonded to each other to form a ring.
n is 0 or a positive integer.
When n is 2 or more, R ^a5 to R ^a8 may be the same or different in each repeating unit.
However, when n is 0, at least one of R ^a1 to R ^a4 and R ^a9 to R ^a12 is not a hydrogen atom.

Specific examples of R ^a1 to R ^a8 include a hydrogen atom; a halogen atom such as fluorine, chlorine, and bromine; and an alkyl group having 1 to 20 carbon atoms. ^{R a1} to R ^a8 may all be different atoms or groups. Some or all of R ^a1 to R ^a8 may be the same atom or group.

Specific examples of R ^a9 to R ^a12 include a hydrogen atom; a halogen atom such as fluorine, chlorine, and bromine; an alkyl group having from 1 to 20 carbon atoms; a cycloalkyl group such as a cyclohexyl group; a substituted or unsubstituted aromatic hydrocarbon group such as a phenyl group, a tolyl group, an ethylphenyl group, an isopropylphenyl group, a naphthyl group, and an anthryl group; and an aralkyl group such as a benzyl group and a phenethyl group. ^{R a9} to R ^a12 may all be composed of different atoms or groups. Some or all of R ^a9 to R ^a12 may be the same atom or group.

Specific examples of the divalent hydrocarbon group that can be formed by combining R ^a9 and R ^a10 , or R ^a11 and R ^a12 together, include alkylidene groups such as an ethylidene group, a propylidene group, and an isopropylidene group.

When R ^a9 or R ^a10 and R ^a11 or R ^a12 are bonded to each other to form a ring, the ring formed may be a monocyclic ring or a polycyclic ring. The ring formed may be a polycyclic ring having a bridge. The ring formed may have a double bond. The ring formed may have a substituent such as a methyl group.

Specific examples of the substituted norbornene represented by formula (I) include 5-methyl-bicyclo[2.2.1]hept-2-ene, 5,5-dimethyl-bicyclo[2.2.1]hept-2-ene, 5-ethyl-bicyclo[2.2.1]hept-2-ene, 5-butyl-bicyclo[2.2.1]hept-2-ene, 5-ethylidene-bicyclo[2.2.1]hept-2-ene, 5-hexyl-bicyclo[2.2.1]hept-2-ene, 5-methyl-bicyclo[2.2.1]hept-2-ene, 5,5-dimethyl-bicyclo[2.2.1]hept-2-ene, 5-ethyl-bicyclo[2.2.1]hept-2-ene, 5-hexyl-bicyclo[2.2.1]hept-2-ene, 5-methyl ... Bicyclic olefins such as cyclo[2.2.1]hept-2-ene, 5-octyl-bicyclo[2.2.1]hept-2-ene, 5-octadecyl-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, and 5-propenyl-bicyclo[2.2.1]hept-2-ene;
Tricyclo[4.3.0.1 ^2,5 ]deca-3,7-diene (trivial name: dicyclopentadiene), tricyclo[4.3.0.1 ^2,5 ]deca-3-ene; tricyclo[4.4.0.1 ^2,5 ]undeca-3,7-diene or tricyclo[4.4.0.1 ^2,5 ]undeca-3,8-diene, or their partially hydrogenated products (or adducts of cyclopentadiene and cyclohexene), tricyclo[4.4.0.1 ^2,5 ]undec-3-ene; three-ring cyclic olefins such as 5-cyclopentyl-bicyclo[2.2.1]hept-2-ene, 5-cyclohexyl-bicyclo[2.2.1]hept-2-ene, 5-cyclohexenylbicyclo[2.2.1]hept-2-ene, and 5-phenyl-bicyclo[2.2.1]hept-2-ene;
Tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene (also simply called tetracyclododecene), 8-methyltetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene, 8-ethyltetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene, 8-methylidenetetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene, 8-ethylidenetetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene, 8-vinyltetracyclo[4,4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene, 8-propenyl-tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene and other tetracyclic olefins;
8-Cyclopentyl-tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene, 8-cyclohexyl-tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene, 8-cyclohexenyl-tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene, 8-phenyl-cyclopentyl-tetracyclo[4.4.0.1 ^2,5 . 1 ^7,10 ]dodec-3-ene; tetracyclo[7.4.1 ^3,6 . 0 ^1,9 . 0 ^2,7 ]tetradeca-4,9,11,13-tetraene (also known as 1,4-methano-1,4,4a,9a-tetrahydrofluorene), tetracyclo[8.4.1 ^4,7 . 0 ^1,10 . 0 ^3,8 ]pentadeca-5,10,12,14-tetraene (also known as 1,4-methano-1,4,4a,5,10,10a-hexahydroanthracene); pentacyclo[6.6.1.1 ^3,6 . 0 ^2,7 . 0 ^9,14 ]-4-hexadecene, pentacyclo[6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ]-4-pentadecene, pentacyclo[7.4.0.0 ^2,7 . 1 ^3,6 . 1 ^10,13 ]-4-pentadecene; heptacyclo[8.7.0.1 ^2,9 . 1 ^4,7 . 1 ^11,17 . 0 ^3,8 . 0 ^12,16 ]-5-eicosene, heptacyclo[8.7.0.1 ^2,9 . 0 ^3,8 . 1 ^4,7 . 0 ^12,17 . ^{1 13,16} ]-14-eicosene; and polycyclic olefins such as a tetramer of cyclopentadiene.

Among these, alkyl-substituted norbornenes such as bicyclo[2.2.1]hept-2-ene substituted with one or more alkyl groups, and alkylidene-substituted norbornenes substituted with one or more alkylidene groups such as bicyclo[2.2.1]hept-2-ene are preferred. 5-Ethylidene-bicyclo[2.2.1]hept-2-ene (common name: 5-ethylidene-2-norbornene, or simply ethylidenenorbornene) is particularly preferred.

[α-Olefin]
The α-olefin is an α-olefin having 3 to 20 carbon atoms.
As such an α-olefin, not only unsubstituted α-olefins but also substituted α-olefins having a substituent such as a halogen atom can be used. The number of carbon atoms in the α-olefin is 3 to 20, preferably 4 to 12, and more preferably 6 to 10.

Specific examples of α-olefins having 3 to 12 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, and 1-dodecene. Of these, 1-hexene, 1-octene, and 1-decene are preferred.

[(A) Method for producing cyclic olefin copolymer]
The method for producing the cyclic olefin copolymer (A) will be described below.
(A) A method for producing a cyclic olefin copolymer includes addition polymerizing a cyclic olefin monomer and an α-olefin in the presence of a titanocene catalyst represented by the following formula (1) and a co-catalyst, wherein the co-catalyst includes a borate compound and a hindered phenol.
In the above production method, the cyclic olefin monomer and the α-olefin are each added in two or more batches to the reaction system where addition polymerization is carried out.
(In formula (1), R ¹ to R ³ are each independently an alkyl group having from 1 to 6 carbon atoms or an aryl group having from 6 to 12 carbon atoms; R ⁴ and R ⁵ are each independently an alkyl group having from 1 to 12 carbon atoms, an aryl group having from 6 to 12 carbon atoms, or a halogen atom; and R ⁶ to R ¹³ are each independently a hydrogen atom, an alkyl group having from 1 to 12 carbon atoms, an aryl group having from 6 to 12 carbon atoms, or a silyl group which may have a monovalent hydrocarbon group having from 1 to 12 carbon atoms as a substituent.)

This method makes it possible to provide a cyclic olefin copolymer (A) that satisfies any of the constituent requirements (I) to (III) described above. Hereinafter, this method will also be referred to as the "first production method."

The following production method is also preferred as a method for producing the cyclic olefin copolymer (A). This method can provide the cyclic olefin copolymer (A) that satisfies the constituent requirements described in (I) or (II) above.
Specifically, this method involves addition polymerizing a cyclic olefin monomer and an α-olefin in the presence of a titanocene catalyst represented by formula (1) and a co-catalyst. The co-catalyst includes a borate compound and a hindered phenol. The addition polymerization is carried out at a temperature ranging from 10°C to 60°C. The titanocene catalyst represented by formula (1) is the same as the titanocene catalyst described above for the first production method.
Hereinafter, this method will also be referred to as the "second manufacturing method."

(First manufacturing method)
In the first production method, a monomer containing the above-mentioned cyclic olefin monomer and an α-olefin is used. The types of the cyclic olefin monomer, the types of the α-olefin, and the copolymerization ratio thereof are the same as those described for (A) the cyclic olefin copolymer.

In the first production method, the cyclic olefin monomer and the α-olefin are each added in two or more batches to a reaction system where addition polymerization is carried out.
By adding the cyclic olefin monomer and the α-olefin in this way, it is easy to obtain a cyclic olefin copolymer (A) having good mechanical properties.Furthermore, by adding the cyclic olefin monomer and the α-olefin in this way, it is easy to obtain a cyclic olefin copolymer (A) having a glass transition temperature in the range of less than 0°C.

When adding the compound in portions, the number of portions is not particularly limited. For example, the number of portions is preferably 2 or more and 5 or less, more preferably 2 or 3, and even more preferably 2.
When adding in portions, the amount of cyclic olefin monomer or α-olefin added per portion is preferably TA/N×0.5 or more and TA/N×1.5 or less, more preferably TA/N×0.7 or more and TA/N×1.3 or less, and even more preferably TA/N×0.9 or more and TA/N×1.1 or less, where TA is the mass of the total amount added and N is the number of portions added.

When the number of divisions is two, the amount of cyclic olefin monomer or α-olefin added per division is preferably 25% by mass or more and 75% by mass or less, more preferably 35% by mass or more and 65% by mass or more, and even more preferably 45% by mass or more and 55% by mass or less, based on the total mass of the added amount.

When the divided addition is carried out, at least one of the cyclic olefin monomer and the α-olefin is added to the reaction vessel at or before the start of the addition polymerization, and then, at any timing after the start of the addition polymerization, the second or subsequent addition of the cyclic olefin monomer or the α-olefin is carried out.
When the addition is carried out in portions, the time between each addition is preferably 3 minutes or more and 20 minutes or less, more preferably 5 minutes or more and 15 minutes or less.
When the divided additions are carried out, the timing of addition of the cyclic olefin monomer and the timing of addition of the α-olefin may be simultaneous or different.
The number of times the cyclic olefin monomer is added may be different from the number of times the α-olefin is added.

As described above, when producing the cyclic olefin copolymer (A), the titanocene catalyst represented by the above formula (1) is used.
In formula (1), R ¹ to R ³ are each independently an alkyl group having from 1 to 6 carbon atoms or an aryl group having from 6 to 12 carbon atoms. Specific examples thereof include alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a cyclopentyl group, and a cyclohexyl group; and aryl groups such as a phenyl group, a biphenyl group, a phenyl group or a biphenyl group having the above alkyl group as a substituent, a naphthyl group, and a naphthyl group having the above alkyl group as a substituent.

^R4 and ^R5 each independently represent an alkyl group having from 1 to 12 carbon atoms, an aryl group having from 6 to 12 carbon atoms, or a halogen atom. Specific examples thereof include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom; a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a cyclopentyl group, a cyclohexyl group, and alkyl groups thereof having the above-mentioned halogen atoms as a substituent; a phenyl group, a biphenyl group, a naphthyl group, and aryl groups thereof having the above-mentioned halogen atoms or alkyl groups as a substituent.

R ⁶ to R ¹³ are each independently a hydrogen atom, an alkyl group having from 1 to 12 carbon atoms, an aryl group having from 6 to 12 carbon atoms, or a silyl group which may have a monovalent hydrocarbon group having from 1 to 12 carbon atoms as a substituent. Specific examples of the alkyl group having from 1 to 12 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a cyclopentyl group, and a cyclohexyl group. Specific examples of the aryl group having from 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a naphthyl group, and any of these aryl groups having the above alkyl group as a substituent. Furthermore, specific examples of the silyl group having a monovalent hydrocarbon group having from 1 to 12 carbon atoms as a substituent include silyl groups having an alkyl group having from 1 to 12 carbon atoms as a substituent, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a cyclopentyl group, or a cyclohexyl group.

Specific examples of the titanocene catalyst represented by the general formula (1) include (isopropylamido)dimethyl-9-fluorenylsilanetitanium dimethyl, (isobutylamido)dimethyl-9-fluorenylsilanetitanium dimethyl, (t-butylamido)dimethyl-9-fluorenylsilanetitanium dimethyl, (isopropylamido)dimethyl-9-fluorenylsilanetitanium dichloride, (isobutylamido)dimethyl-9-(3,6-dimethylfluorenyl)silanetitanium dichloride, (t-butylamido)dimethyl-9-fluorenylsilanetitanium dichloride, ( (isopropylamido)dimethyl-9-(3,6-dimethylfluorenyl)silanetitanium dichloride, (isobutylamido)dimethyl-9-(3,6-dimethylfluorenyl)silanetitanium dichloride, (t-butylamido)dimethyl-9-(3,6-dimethylfluorenyl)silanetitanium dimethyl, (isopropylamido)dimethyl-9-[3,6-di(i-propyl)fluorenyl]silanetitanium dichloride, (isobutylamido)dimethyl-9-[3,6-di(i-propyl)fluorenyl]silanetitanium dichloride, (t-butylamido)dimethyl t-butylamido)dimethyl-9-[3,6-di(t-butyl)fluorenyl]silanetitanium dimethyl, (isopropylamido)dimethyl-9-[3,6-di(t-butyl)fluorenyl]silanetitanium dichloride, (isobutylamido)dimethyl-9-[3,6-di(t-butyl)fluorenyl]silanetitanium dichloride, (t-butylamido)dimethyl-9-[3,6-di(t-butyl)fluorenyl]silanetitanium dimethyl, (isopropylamido)dimethyl-9-[2,7-di(t-butyl)fluorenyl]silanetitanium dichloride, (isobutylamido)dimethyl Examples of such silane titanium compounds include (t-butylamido)dimethyl-9-[2,7-di(t-butyl)fluorenyl]silanetitanium dichloride, (t-butylamido)dimethyl-9-[2,7-di(t-butyl)fluorenyl]silanetitanium dimethyl, (isopropylamido)dimethyl-9-(2,3,6,7-tetramethylfluorenyl)silanetitanium dichloride, (isobutylamido)dimethyl-9-(2,3,6,7-tetramethylfluorenyl)silanetitanium dichloride, (t-butylamido)dimethyl-9-(2,3,6,7-tetramethylfluorenyl)silanetitanium dimethyl, etc. Preferred is (t-butylamido)dimethyl-9-fluorenylsilanetitanium dimethyl ((t-BuNSiMe ₂ Flu)TiMe ₂ ). (t-BuNSiMe ₂ Flu)TiMe ₂ is a titanium complex represented by the following formula (2), and can be easily synthesized, for example, based on the description in "Macromolecules, Vol. 31, p. 3184, 1998."

(In the formula, Me represents a methyl group, and t-Bu represents a tert-butyl group.)

The amount of the titanocene catalyst used is not particularly limited as long as the addition polymerization reaction proceeds smoothly. The amount of titanocene catalyst used is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the total amount of cyclic olefin monomer and α-olefin.

The addition polymerization of a cyclic olefin monomer and a monomer containing an α-olefin is carried out in the presence of the titanocene catalyst and a co-catalyst, which includes a borate compound and a hindered phenol.
By carrying out addition polymerization in the presence of the titanocene catalyst and a cocatalyst so as to satisfy the above-mentioned predetermined conditions, a cyclic olefin copolymer (A) having both excellent breaking strain and excellent toughness can be obtained.

As the borate compound, any borate compound that has traditionally been used as a co-catalyst in the homopolymerization or copolymerization of cyclic olefin monomers can be used without particular limitation. Specific preferred examples of borate compounds include triphenylmethylium tetrakis(pentafluorophenyl)borate, dimethylphenylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, and N-methyldin-normal-decylammonium tetrakis(pentafluorophenyl)borate.

As the hindered phenol, any hindered phenol that has been conventionally used as a co-catalyst in the homopolymerization or copolymerization of cyclic olefin monomers can be used without any particular limitation.
Here, the hindered phenol refers to a phenol having a bulky substituent at least on one of the two adjacent positions to the phenolic hydroxyl group. Examples of the bulky substituent include alkyl groups other than methyl groups such as isopropyl, isobutyl, sec-butyl, and tert-butyl, alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups, alkoxy groups, aryloxy groups, substituted amino groups, alkylthio groups, and arylthio groups.

Specific examples of hindered phenols include 2,6-di-tert-butyl-4-hydroxytoluene (BHT), 2,6-di-tert-butylphenol, 2-tert-butylphenol, 2-tert-butyl-p-cresol, 3,3',5,5'-tetra-tert-butyl-4,4'-dihydroxybiphenyl, and 3,3',5,5'-tetra-tert-butyl-2,2'-dihydroxybiphenyl. phenol, 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 4,4',4"-(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol), and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylmethyl)2,4,6-trimethylbenzene.
Among these, 2,6-di-tert-butyl-4-hydroxytoluene (BHT) and 2,6-di-tert-butylphenol are preferred because they have a small molecular weight and the desired effect of using a hindered phenol can be easily obtained by using a small amount.

Furthermore, the hindered phenol can increase the yield of the cyclic olefin copolymer by reacting with the alkylaluminum compound in the polymerization system, and therefore it is preferred that the co-catalyst further contains an alkylaluminum compound.
Specific examples of the alkylaluminum compound include trialkylaluminums such as trimethylaluminum, triethylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-sec-butylaluminum, and tri-n-octylaluminum; dialkylaluminum halides such as dimethylaluminum chloride and diisobutylaluminum chloride; dialkylaluminum hydrides such as diisobutylaluminum hydride; and dialkylaluminum alkoxides such as dimethylaluminum methoxide.

The amount of the borate compound used is not particularly limited, as long as the addition polymerization reaction proceeds smoothly and a cyclic olefin copolymer with the desired properties is obtained. The amount of the borate compound used is preferably 0.01 parts by mass or more and 100 parts by mass or less, more preferably 0.1 parts by mass or more and 10 parts by mass or less, and even more preferably 1 part by mass or more and 5 parts by mass or less, per 100 parts by mass of the total amount of the cyclic olefin monomer and α-olefin.

The amount of the hindered phenol used is not particularly limited, as long as the addition polymerization reaction proceeds smoothly and a cyclic olefin copolymer with the desired properties is obtained. The amount of hindered phenol used is preferably 0.001 to 100 parts by mass, more preferably 0.01 to 10 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the total amount of cyclic olefin monomer and α-olefin.

The amount of the alkylaluminum compound used is not particularly limited, as long as the addition polymerization reaction proceeds smoothly and a cyclic olefin copolymer with the desired properties is obtained. The amount of the alkylaluminum compound used is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the total amount of the cyclic olefin monomer and α-olefin.

The addition polymerization may be carried out in the presence of a solvent. The solvent is not particularly limited as long as it does not inhibit the polymerization reaction. Preferred solvents include hydrocarbon solvents and halogenated hydrocarbon solvents, with hydrocarbon solvents being preferred due to their ease of handling, thermal stability, and chemical stability. Specific examples of preferred solvents include hydrocarbon solvents such as pentane, hexane, heptane, octane, isooctane, isododecane, mineral oil, cyclohexane, methylcyclohexane, decahydronaphthalene (decalin), benzene, toluene, and xylene, and halogenated hydrocarbon solvents such as chloroform, methylene chloride, dichloromethane, dichloroethane, and chlorobenzene.

The solvent may be charged into the polymerization vessel alone, or in the form of a monomer solution, catalyst solution, or cocatalyst solution.

When a solvent is used, its amount is not particularly limited. The amount of solvent used is preferably 100 parts by mass or more and 100,000 parts by mass or less, more preferably 500 parts by mass or more and 10,000 parts by mass or less, and even more preferably 1,000 parts by mass or more and 5,000 parts by mass or less, per 100 parts by mass of the total amount of cyclic olefin monomer and α-olefin.

The temperature of the addition polymerization is not particularly limited and is, for example, preferably −20° C. or higher and 200° C. or lower, more preferably −10° C. or higher and 10° C. or lower, and even more preferably −5° C. or higher and 5° C. or lower.
When producing a cyclic olefin copolymer having a glass transition temperature in the range of less than 0°C, in the range of 0°C to 100°C, or in the range of 160°C to 300°C, the temperature of the addition polymerization is preferably −20°C or higher and lower than 10°C.
The time for addition polymerization is not particularly limited, and is, for example, preferably from 5 minutes to 30 minutes, more preferably from 8 minutes to 20 minutes, and even more preferably from 10 minutes to 15 minutes.

The atmosphere in which the above-mentioned addition polymerization reaction is carried out is not particularly limited, but an inert gas atmosphere is preferred. Examples of inert gases that can be used include nitrogen gas and helium gas.

After addition polymerization is carried out as described above to produce (A) cyclic olefin copolymer, (A) cyclic olefin copolymer is recovered from the reaction vessel using conventional methods.

(Second manufacturing method)
The second production method is similar to the first production method, except that the method for charging the cyclic olefin monomer and the α-olefin is not particularly limited, and the addition polymerization is carried out at a temperature in the range of 10°C or higher and 60°C or lower.

In the second production method, the method for charging the cyclic olefin monomer and α-olefin may be the same as in the first production method. Because the charging operation is simple, the method for charging the cyclic olefin monomer and α-olefin in the second production method is preferably a method in which the cyclic olefin monomer and α-olefin are charged all at once into the reaction vessel at or before the start of the addition polymerization reaction.

<(B) Hindered phenol-based antioxidant>
As the (B) hindered phenol-based antioxidant, any hindered phenol-based antioxidant that has conventionally been blended in various resin compositions can be used without any particular limitation.
Here, the definition of the hindered phenol is the same as the definition of the hindered phenol explained in the first production method.

(B) Specific examples of hindered phenol antioxidants include 2,2'-methylenebis(4-methyl-6-tert-butylphenol), hexamethylene glycol-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), pentaerythritol-tetrakis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, n-octadecyl-3-(4'-hydroxy-3',5 '-di-tert-butylphenol) propionate, 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-butylidene-bis(6-tert-butyl-3-methyl-phenol), di-stearyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 2-t-butyl-6-(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenyl acrylate, and 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane, etc.

As described above, the content of the hindered phenol-based antioxidant (B) is 0.1 to 2.0 parts by mass based on 100 parts by mass of the cyclic olefin copolymer (A).
Since adverse effects due to volatilization or sublimation of the (B) hindered phenol-based antioxidant itself or decomposition products of the (B) hindered phenol-based antioxidant are small when continuously producing press-molded articles, the content of the (B) hindered phenol-based antioxidant is preferably 0.1 to 1.0 parts by mass, and more preferably 0.1 to 0.5 parts by mass, relative to 100 parts by mass of the (A) cyclic olefin copolymer.

<Other additives>
The press-molding resin composition may contain additives other than (A) the cyclic olefin copolymer and (B) the hindered phenol antioxidant, as long as the desired effects are not impaired.
Examples of other additives include antioxidants other than the (B) hindered phenol-based antioxidant, weather stabilizers, ultraviolet absorbers, antibacterial agents, flame retardants, colorants, reinforcing materials, fillers, etc. These additives are added to the press-molding resin composition in amounts taking into account the typical amounts used depending on the type of additive.
The other additives may be used alone or in combination of two or more.

When the press-molding resin composition contains the other additives described above, the ratio of the mass of the other additives to the mass of the press-molding resin composition is not particularly limited as long as the desired effects are not impaired.
The mass ratio of the other additives to the mass of the resin composition for press molding can be adjusted appropriately depending on the effect to be obtained.

<Method of producing a resin composition for press molding>
The method for producing the press-molding resin composition is not particularly limited as long as it is a method that can uniformly mix (A) the cyclic olefin copolymer, (B) the hindered phenol antioxidant, and, if necessary, other additives.
A preferred method for producing the press-molding resin composition includes melt-kneading (A) the cyclic olefin copolymer, (B) the hindered phenol antioxidant, and, if necessary, other additives, using a melt-kneading device such as a single-screw extruder or a multi-screw extruder having two or more screws.

The form of the press-molding resin composition is not particularly limited. The press-molding resin composition may be in the form of powder, flakes, or pellets. Typically, the press-molding resin composition is discharged in the form of strands from a melt kneading device. The strand-shaped press-molding resin composition is cooled and solidified, and then cut into pellets.

<Press-molded body>
The press-molded article is a molded article obtained by press-molding the above-mentioned resin composition for press molding.
The press-molded article has excellent fracture strain and excellent toughness, and is little colored, and is therefore suitable for use in optical applications, medical applications, packaging applications, electrical and electronic parts applications, industrial and commercial part applications, and the like.

Furthermore, the press-molded body exhibits a low relative dielectric constant and a low dielectric loss tangent in the high frequency band, and is therefore suitable for use as a component or substrate material for electric or electronic devices used in the high frequency band.
Specifically, the press-molded body exhibits a relative dielectric constant of 2.2 or less and a dielectric loss tangent of 3.0×10 ⁻⁴ or less at 40 GHz.
The press-molded article is preferably used as a material for a high-frequency printed circuit board, particularly a transparent conductive laminate used as a high-frequency printed circuit board.

The press molding method is not particularly limited, and any well-known press molding method can be used without any particular limitation.
The conditions for press molding are, for example, a temperature of 200 to 340° C. and a pressure of 5 to 20 MPa (G).
The thickness of the press-molded body is appropriately selected depending on the application of the press-molded body. The thickness of the press-molded body may be uniform throughout or may vary from part to part. The thickness of the press-molded body is typically preferably 30 to 150 μm, more preferably 50 to 100 μm.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

[Examples 1 to 3]
In Examples 1 to 3, 2-norbornene (Nb) and 1-octene (Octene) were used in the ratios shown in Table 1, with the total amount of 2-norbornene and 1-octene being 118.8 mmol. A 500 mL eggplant-shaped flask purged with nitrogen was charged with half the amounts of 2-norbornene and 1-octene, 0.198 mmol of tri-n-octylaluminum, and 0.396 mmol of 2,6-di-tert-butyl-4-hydroxytoluene. The contents of the flask were then diluted with toluene to a volume of 258 mL. The contents of the flask were then cooled to 0°C. After cooling, a toluene solution containing a titanocene catalyst at a concentration of 0.04 mmol/L was added to the reaction mixture to adjust the amount of titanocene catalyst to 0.22 mmol. The titanocene catalyst used was the compound represented by the aforementioned formula (2). Next, a toluene solution of a borate compound with a concentration of 0.008 mmol/L was added to the reaction solution so that the amount of borate compound was 0.22 mmol. Triphenylmethylium tetrakis(pentafluorophenyl)borate was used as the borate compound. After adding the titanocene catalyst and the borate compound to initiate addition polymerization, the reaction solution was stirred with a magnetic stirrer and reacted for 10 minutes at 0°C. After the 10-minute reaction, the remaining half of the amounts of 2-norbornene and 1-octene, along with 0.022 mmol of tri-n-octylaluminum and 0.044 mmol of 2,6-di-tert-butyl-4-hydroxytoluene, were added to the eggplant-shaped flask. The addition polymerization reaction was then continued for 15 minutes.
After a total of 25 minutes of reaction, a small amount of 2-propanol was added to the reaction solution to terminate the addition polymerization reaction. Hydrochloric acid was added to the reaction solution and stirred for 10 minutes, and then the organic layer was washed with ion-exchanged water. Washing with ion-exchanged water was repeated until the aqueous layer became neutral, and the washed organic layer was recovered. The recovered organic layer was added dropwise to a large amount of acetone to precipitate the produced cyclic olefin copolymer. The precipitated copolymer was recovered by filtration, and then washed twice or more with methanol and acetone. The washed copolymer was dried under reduced pressure at 110°C for 16 hours or more to obtain a dried cyclic olefin copolymer.

For the resulting cyclic olefin copolymer, the ratio of the number of moles of structural units derived from α-olefin (1-octene) (α-olefin ratio) was determined by the following method.
About 50 mg of the obtained cyclic olefin copolymer was dissolved in 0.6 mL of chloroform-d, and the 13C-NMR spectrum was measured using a BRUKER AVANCE III 400+ cryoprobe under the conditions of 300 K, 90° pulse, repetition time 30 seconds, and accumulation 1000 times.
From the obtained spectrum, the ratio of α-olefin was calculated based on the following formula in accordance with the method described in Macromolecules 2010, 43, 4527-4531. The results are shown in Table 1 as the Oct ratio in the resin.
Ratio of α-olefin (mol %)=[integral value of carbon derived from α-olefin/(integral value of carbon derived from α-olefin+integral value of carbon derived from cyclic olefin monomer)]×100

The resulting cyclic olefin copolymer was subjected to molecular weight measurement by gel permeation chromatography, glass transition temperature measurement by the method described above, and tensile testing by the same method. The results of these measurements are shown in Table 1. The tensile test was conducted in accordance with ISO 527-3 using a tensile tester (Tensilon Universal Testing Machine RTM-100, manufactured by A&D Co., Ltd.) at a temperature of 23°C, a chuck distance of 50 mm, and a tensile speed of 50 mm/min.

The films used as samples in the measurement of glass transition temperature and the tensile test were prepared by the following method.
A mold with a depth of 50 μm was prepared using Kapton (registered trademark) film measuring 10 cm × 10 cm × 50 μm. The mold was filled with the obtained cyclic olefin copolymer, and then the cyclic olefin copolymer filled in the mold was vacuum-pressed using a hot vacuum press under conditions of a pressure of 15 MPa, a temperature of 320 to 340°C, and a time of 15 minutes. After pressing, the pressed cyclic olefin copolymer was rapidly cooled by sandwiching it between metal plates at room temperature. After cooling, the metal plates were removed, and a cyclic olefin copolymer film with a thickness of approximately 50 μm was obtained.

100 parts by mass of the cyclic olefin copolymer obtained according to the method described above and 0.15 parts by mass of a hindered phenol-based antioxidant (pentaerythritol-tetrakis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) were melt-kneaded under the following extrusion conditions using a small bench-top extruder (bench-top extruder AS-1, manufactured by Apex Japan Co., Ltd.), and the molten mixture was then pelletized to obtain a resin composition for press molding.
[Extrusion conditions]
(Cylinder temperature)
Example 1: 330°C
Example 2: 310°C
Example 3: 290°C

The film-like press-molded articles used as samples in the measurements of the relative dielectric constant and the dielectric loss tangent and the Δb value were produced using the obtained press-molding resin compositions by the following method.
First, a 10 cm x 10 cm x 50 μm mold was prepared using a 15 cm x 15 cm x 50 μm Kapton (registered trademark) film. The mold was filled with the obtained press-molding resin composition, and then the press-molding resin composition filled in the mold was vacuum-pressed using a thermal vacuum press (Imoto Machinery Co., Ltd., small vacuum heating press IMC-11FA model) under the following pressing conditions. After pressing, the pressed press-molding resin composition was rapidly cooled by sandwiching it between metal plates at room temperature. After cooling, the metal plates were removed, and a 10 cm x 10 cm x 50 μm film-like press-molded product of the press-molding resin composition with a film thickness of approximately 50 μm was obtained.
[Pressing conditions]
(temperature)
Example 1: 330°C
Example 2: 310°C
Example 3: 290°C
(pressure)
Examples 1 to 3: 15 MPa (G)
(time)
Examples 1 to 3: 15 minutes

The dielectric constant and dielectric loss tangent at a frequency of 40 GHz were measured for the obtained press-molded body according to the following method. The Δb value was also measured for the obtained press-molded body according to the following method. The measurement results are shown in Table 2.

<Dielectric property measurement>
A test piece measuring 3 cm × 3 cm × 50 μm was cut out from the obtained press-molded body, and used as a sample for measuring dielectric properties. The relative permittivity and dielectric loss tangent of this sample were measured at a frequency of 40 GHz using a split cylinder resonator perturbation method complex permittivity evaluation device.

<Δb value measurement>
A 3 cm x 3 cm x 50 μm test piece was cut out from the obtained press-molded body and used as a sample for measuring the Δb value. This sample was heat-treated at 150 ° C. for 168 hours using a gear oven (Espec Corporation, rotating frame-equipped incubator Gear Oven GPH202). The b value was measured using a color difference meter (Nippon Denshoku Industries Co., Ltd., Spectrophotometer SE6000), and the difference in the b value (Δb value) before and after the heat treatment was calculated.

[Comparative Example 1]
A cyclic olefin copolymer was obtained in the same manner as in Example 1, except that the norbornene and 1-octene were charged in their entirety all at once before the initiation of the addition polymerization reaction, the reaction temperature was changed to 40°C, and the reaction time was changed to 4 hours. The charging ratio of norbornene and 1-octene is as shown in Table 1.
The obtained cyclic olefin copolymer was subjected to measurement of the Oct ratio in the resin, measurement of the molecular weight by gel permeation chromatography, measurement of the glass transition temperature by the above-mentioned method, and tensile testing by the above-mentioned method, in the same manner as in Example 1. The results of these measurements are shown in Table 1.

Pellets of a resin composition for press molding were obtained in the same manner as in Example 1, using 100 parts by mass of the cyclic olefin copolymer obtained according to the method described above and 0.15 parts by mass of a hindered phenol-based antioxidant (pentaerythritol-tetrakis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), except that the cylinder temperature of the extruder was changed to 310°C.

A press-molded body was obtained using the obtained press-molding resin composition in the same manner as in Example 1, except that the press temperature was changed to 310°C. The relative permittivity and dielectric loss tangent at a frequency of 40 GHz were measured for the obtained press-molded body in the same manner as in Example 1. The Δb value was also measured for the obtained press-molded body. The measurement results are shown in Table 2.

[Comparative Example 2]
A cyclic olefin copolymer was obtained in the same manner as in Example 1, except that 0.97 mmol of CC1 below and 0.68 mmol of CC2 below were used as cocatalysts, the reaction temperature was changed to 40° C., and the polymerization time was changed to 4 hours. The charging ratios and charging methods of norbornene and 1-octene are as shown in Table 1.
The obtained cyclic olefin copolymer was subjected to measurement of the Oct ratio in the resin, measurement of the molecular weight by gel permeation chromatography, measurement of the glass transition temperature by the above-mentioned method, and tensile testing by the above-mentioned method, in the same manner as in Example 1. The results of these measurements are shown in Table 1.
CC1: 6.5 mass% (as Al atom content) MMAO-3A toluene solution (a solution of methylisobutylaluminoxane represented by [(CH ₃ ) _0.7 (iso-C ₄ H ₉ ) _0.3 AlO] _n , manufactured by Tosoh Finechem Corporation, containing 6 mol% trimethylaluminum based on the total Al).
CC2: 9.0 mass% (as Al atom content) TMAO-211 toluene solution (methylaluminoxane solution, manufactured by Tosoh Finechem Co., Ltd., containing 26 mol% trimethylaluminum based on the total Al)

Pellets of a resin composition for press molding were obtained in the same manner as in Example 1, using 100 parts by mass of the cyclic olefin copolymer obtained according to the method described above and 0.15 parts by mass of a hindered phenol-based antioxidant (pentaerythritol-tetrakis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), except that the cylinder temperature of the extruder was changed to 340°C.

A press-molded body was obtained using the obtained press-molding resin composition in the same manner as in Example 1, except that the press temperature was changed to 340°C. The relative permittivity and dielectric loss tangent at a frequency of 40 GHz were measured for the obtained press-molded body in the same manner as in Example 1. The Δb value was also measured for the obtained press-molded body. The measurement results are shown in Table 2.

[Comparative Example 3]
A cyclic olefin copolymer was obtained in the same manner as in Comparative Example 1, except that only 0.22 mmol of triphenylmethylium tetrakis(pentafluorophenyl)borate was used as the co-catalyst, the reaction temperature was changed to 25° C., and the reaction time was changed to 2 hours. The charging ratios of norbornene and 1-octene are as shown in Table 1.
The obtained cyclic olefin copolymer was subjected to measurement of the Oct ratio in the resin, measurement of the molecular weight by gel permeation chromatography, measurement of the glass transition temperature by the above-mentioned method, and tensile testing by the above-mentioned method, in the same manner as in Example 1. The results of these measurements are shown in Table 1.

Pellets of a resin composition for press molding were obtained in the same manner as in Example 1, using 100 parts by mass of the cyclic olefin copolymer obtained according to the method described above and 0.15 parts by mass of a hindered phenol-based antioxidant (pentaerythritol-tetrakis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), except that the cylinder temperature of the extruder was changed to 270°C.

A press-molded body was obtained using the obtained press-molding resin composition in the same manner as in Example 1, except that the press temperature was changed to 270°C. The relative permittivity and dielectric loss tangent at a frequency of 40 GHz were measured for the obtained press-molded body in the same manner as in Example 1. The Δb value was also measured for the obtained press-molded body. The measurement results are shown in Table 2.

Tables 1 and 2 show that the cyclic olefin copolymers (A) prepared in Examples 1 to 3, in which the ratio of the number of moles of structural units derived from α-olefin to the number of moles of all structural units is 10 mol % or more and 40 mol % or less, and which have two or more glass transition temperatures determined by viscoelasticity measurement within the range of 0°C to 300°C, exhibit excellent tensile properties and combine excellent strain at break with excellent toughness.
Therefore, the press-molded articles obtained using the press-molding compositions containing the cyclic olefin copolymers (A) prepared in Examples 1 to 3 also have excellent fracture strain and excellent toughness.
Furthermore, the press-molding resin compositions of Examples 1 to 3, which contained the hindered phenol-based antioxidant (B), also showed little discoloration during press molding.
Furthermore, the press-molded articles obtained in Examples 1 to 3 exhibited low relative permittivity and dielectric loss tangent at a frequency of 40 GHz.
On the other hand, the cyclic olefin copolymers (A) prepared in Comparative Examples 1 to 3, each of which had only one glass transition temperature within the range of 0°C to 300°C as determined by viscoelasticity measurement, were inferior in at least one of tensile strength, breaking strain, and tensile modulus.
Furthermore, the press-molding resin compositions of Comparative Examples 1 to 3 were significantly discolored during press molding, despite containing the hindered phenol-based antioxidant (B).

Claims (3)

A press-molding resin composition comprising (A) a cyclic olefin copolymer and (B) a hindered phenol-based antioxidant,
The cyclic olefin copolymer (A) is an addition polymer of a cyclic olefin monomer and an α-olefin having 3 to 20 carbon atoms,
the ratio of the number of moles of structural units derived from the α-olefin to the number of moles of all structural units of the cyclic olefin copolymer (A) is 10 mol % or more and 40 mol % or less,
the cyclic olefin copolymer (A) has at least one glass transition temperature measured by viscoelasticity measurement in the range of less than 0°C, at least one glass transition temperature measured by viscoelasticity measurement in the range of 0°C to 100°C, and at least one glass transition temperature measured by viscoelasticity measurement in the range of 160°C to 300°C,
The press-molding resin composition has a content of the hindered phenol-based antioxidant (B) of 0.1 to 2.0 parts by mass per 100 parts by mass of the cyclic olefin copolymer (A). A press-molded article made from the press-molding resin composition according to claim 1 . The press-molded body according to claim 2 , having a relative dielectric constant of 2.2 or less and a dielectric dissipation factor of 3.0 × 10 ^or less at a measurement frequency of 40 GHz.