JP2002201213A - Hydrogenated styrenic copolymer and optical material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogenated styrenic copolymer having high heat resistance (heat distortion temperature), and excellent moldability and mechanical properties as well. SOLUTION: The hydrogenated styrenic copolymer can be obtained by subjecting a styrenic copolymer substantially free from a long chain of the unit derived from an α-substituted styrenic monomer which is obtained by polymerizing a styrenic monomer, the α-substituted styrenic monomer, and optionally a conjugated diene monomer and meets five formulae: (1) 42<=x<=95, (2) 3<=y<=40, (3) 0<=z<=30, (4) x+y+z=100, and (5) 0.05<=y/(x+y)<=0.40 (wherein x is an amount by wt.% of the unit derived from the styrenic monomer; y is an amount by wt.% of the unit derived from the α-substituted styrenic monomer; and z is an amount by wt.% of the unit derived from the conjugated diene monomer) to hydrogenation reaction in the presence of a hydrogenation catalyst to hydrogenate the aromatic rings and the carbon-carbon double bonds present in the copolymer. An optical material is composed of the hydrogenated styrenic copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel hydrogenated styrene copolymer and the like. More specifically, a unit derived from an α-substituted styrene-based monomer having excellent heat resistance, moldability, transparency, optical isotropy, dimensional stability (low water absorption) and / or mechanical properties, and if necessary The present invention relates to a hydrogenated styrene-based copolymer containing a unit derived from a conjugated diene monomer, a method for producing the same, and an optical material mainly comprising such a hydrogenated styrene-based copolymer.

[0002]

2. Description of the Related Art In addition to transparency, plastics used for optical materials such as optical disks, optical lenses, and liquid crystal display substrates have optical isotropy (low birefringence), dimensional stability, light resistance, and weather resistance. Various characteristics such as heat stability and thermal stability are required. Conventionally, polycarbonate or polymethyl methacrylate has been used as these transparent plastics.

However, polycarbonate has an aromatic ring in its molecule, so that it has a large intrinsic birefringence and optical anisotropy is likely to occur in a molded product. Polymethyl methacrylate has an extremely high water absorption, so that it has a large size. Poor stability and low physical heat resistance have been problems.

As for the optical disk substrate, polycarbonate is currently exclusively used, but in recent years, it is represented by the development of a large capacity magneto-optical recording disk (MOD), the development of a digitally versatile disk (DVD), and the development of a blue laser. As the recording density has been increased, there has been a growing concern about the size of the birefringence of the polycarbonate and the warpage of the disk due to moisture absorption.

[0005] Under these circumstances, amorphous polyolefin-based resins have been actively developed in recent years as substitutes for polycarbonate. As an example of these, hydrogenated polystyrene in which the aromatic ring of polystyrene is hydrogenated to have a polyvinylcyclohexane structure, and a copolymer thereof have been proposed. For example, Japanese Patent Publication No. Hei 7-140030 discloses an optical disk having a substrate made of hydrogenated polystyrene having a vinylcyclohexane content of 80% by weight or more.

Although this resin has a high light transmittance and a very small birefringence and a low water absorption as compared with polycarbonate, it has a drawback that it is mechanically brittle. Therefore, as an aim of improving the drawbacks of such a resin, a styrene-conjugated diene block copolymer obtained by block copolymerizing styrene with conjugated diene such as isoprene and butadiene to introduce a rubber component is used for optical disk substrates and the like. For example, Japanese Patent Nos. 2668945, 2730053 and the like disclose the use for optical applications.

Although the introduction of such a rubber component improves the mechanical brittleness to some extent, it has a serious drawback that the heat deformation temperature is lowered. An optical disk is often subjected to a heat load during its production process and use. For example, in the production process, in particular, a write-once type optical disk exclusively for recording and reproduction, and an erasable type optical disk for recording-reproduction-erasing / re-recording, etc., have several layers of films such as metal oxides and alloy compounds on the substrate. It is necessary to perform sputtering under a high temperature and a high vacuum, and with a resin having low heat resistance, the entire substrate may be deformed.

In addition, recording, reproducing, erasing,
During an operation such as re-recording, the recording film is expected to reach 200 ° C. or higher due to the irradiation of the high-energy laser, and the substrate is also expected to reach a considerably high temperature, and pits, lands, and grooves may be deformed. Further, when an optical disk is used for in-vehicle use, the optical disk may be left at about 100 ° C. for a long time, and the entire substrate or pits, lands, and grooves may be deformed. The conventional improved hydrogenated styrene-based copolymer cannot sufficiently withstand such a heat load, and development of a resin having high heat resistance has been desired.

By the way, regarding polystyrene, α-
It is well known that the introduction of methylstyrene as a copolymer component improves heat resistance. For example, D. B. Pri
ddy et al. App. Poly. Sci. , 41 volumes,
Pp. 383-390 (1990) report that the introduction of α-methylstyrene improves the glass transition point of the copolymer to about 180 ° C. Therefore, the hydrogenated styrene-α-methylstyrene polymer is also
A similar effect of improving heat resistance is expected.

However, on the other hand, the introduction of α-methylstyrene significantly lowers the thermal decomposition temperature of the resin, and such a decrease in the thermal decomposition temperature makes the hydrogenation reaction of the resin containing α-methylstyrene extremely difficult. For example, M. D. Geh
lsen et al. Poly. Sci. : Part B:
Poly. Phys. 33, pp. 1527-1536 (1995), it is reported that various styrenic polymers were hydrogenated to synthesize poly (vinylcyclohexane) derivatives. It is described that the hydrogenation reaction was not successful due to severe molecular chain cleavage reaction.

The introduction of a unit derived from α-methylstyrene as a copolymerization component of a hydrogenated styrene-based polymer is disclosed in Japanese Patent Publication No. 7-114030 (JP-A-63-43910).
Japanese Patent Application Laid-Open No. Hei.
8015) and Japanese Patent No. 2730053 (Japanese Patent Application Laid-Open No. 1-294721), but specific examples of copolymers containing a unit derived from α-methylstyrene having a specific composition are described. There is no description.

On the other hand, in Example 7 of JP-A-1-132603, a copolymer containing α-methylstyrene as a monomer is described. In this example, the unit of α-methylstyrene is substantially It is considered that it is not contained in the polymer. This is because D. B. Prid
As described in the paper of dy et al., styrene and α-
The copolymerization reactivity ratio of methylstyrene is r ₁ = 60, r ₂ =
Styrene is overwhelmingly more reactive, and α-methylstyrene must be reacted several times as much as styrene in order to introduce a certain amount of α-methylstyrene. However, JP-A-1-132603
This is because in the publication, α-methylstyrene is used only in a fraction of styrene.

Japanese Patent Application Laid-Open No. 60-71619 discloses a production method aimed at a one-to-one copolymer of styrene and α-methylstyrene. However, when the present inventors examined the hydrogenation reaction, As with the α-methylstyrene polymer, a severe molecular chain scission reaction was involved, and it was not possible to obtain a polymer that could be used as a material.

As described above, the production of a hydrogenated copolymer by hydrogenation of a copolymer of an α-substituted styrene-based monomer and a styrene-based monomer such as α-methylstyrene has been described so far. There have been no reported cases. Since the hydrogenation reaction of such a polymer involves an intense molecular chain scission reaction, it has been desired to develop a method of performing hydrogenation by suppressing the molecular chain scission reaction.

[0015] In general, resins used for optical applications such as optical disks are primarily resins having transparency, weather resistance, light resistance, optical isotropy (low birefringence), dimensional stability and thermal stability. In addition to the properties described above, the balance between moldability, heat resistance (thermal deformation temperature) and mechanical properties (particularly toughness) must be satisfied, and hydrogenation with units derived from α-substituted styrene-based monomers is required. For styrenic copolymers,
There has been a desire for a high degree of optimization of the structure to be suitable for optical applications.

[0016]

As is apparent from the prior art, an object of the present invention is to provide a hydrogenated styrene-based copolymer having high heat resistance and excellent moldability and mechanical properties. . Another object of the present invention is to provide a hydrogenated styrene-based copolymer mainly composed of a copolymer of an α-substituted styrene-based monomer and a styrene-based monomer having high heat resistance, excellent moldability, and excellent mechanical properties. Is to provide.

[0017]

Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies and have found that styrene monomers, α-substituted styrene monomers and, if necessary, conjugated diene monomers. It is a polymerized styrene-based copolymer, and there is no long-chain chain of units derived from the α-substituted styrene-based monomer,
If the copolymer has a composition in a certain range, the molecular chain scission reaction during the hydrogenation reaction hardly occurs, and as a result, a hydrogenated styrene-based copolymer having high heat resistance can be obtained, and the hydrogenated styrene-based copolymer can be obtained. They have found that the copolymer can be suitably used for optical materials such as optical disks, and have completed the present invention.

That is, the present invention includes the following inventions. 1. The following formulas (1) to (5) obtained by polymerizing a styrene monomer, an α-substituted styrene monomer and, if necessary, a conjugated diene monomer, 42 ≦ x ≦ 95. 1) 3 ≦ y ≦ 40 (2) 0 ≦ z ≦ 30 (3) x + y + z = 100 (4) 0.05 ≦ y / (x + y) ≦ 0.40 ( 5) (where x is the weight% of the unit derived from the styrene monomer, y
Is a weight% of a unit derived from an α-substituted styrene monomer, and z is a weight% of a unit derived from a conjugated diene monomer). A styrene-based copolymer having substantially no long-chain chain of a unit derived from the styrene-based copolymer is subjected to a hydrogenation reaction in the presence of a hydrogenation catalyst, and the aromatic ring and carbon-carbon double A hydrogenated styrene copolymer obtained by hydrogenating a bond.

2. 2. The hydrogenated styrene-based copolymer according to 1, wherein units derived from the conjugated diene monomer contained in the styrene-based copolymer form a block-type structure. 3. 3. The hydrogenated styrene-based copolymer according to 1 or 2, wherein the molecular weight distribution is 4.0 or less. 4. 4. The hydrogenated styrene-based copolymer according to any one of 1 to 3, which has a heat distortion temperature of 100 to 180 ° C.

[5] 5. The hydrogenated styrene-based copolymer according to any one of 1 to 4, wherein the hydrogenated styrene-based copolymer contains a metal and the content is 10 ppm or less.

6. The styrene-based copolymer is obtained by polymerizing a styrene-based monomer, an α-substituted styrene-based monomer, and if necessary, a conjugated diene monomer at a temperature of 40 to 70 ° C. 6. The method for producing a hydrogenated styrene-based copolymer according to any one of items 1 to 5. 7. When hydrogenating the aromatic ring and the carbon-carbon double bond contained in the styrenic copolymer, the temperature is set to 70 to 220.
7. The method for producing a hydrogenated styrenic copolymer according to 6, wherein the temperature is kept in a range of ° C. 8. An optical material mainly comprising the hydrogenated styrene-based copolymer according to any one of 1 to 5. 9. An optical disc substrate mainly comprising the hydrogenated styrene-based copolymer according to any one of claims 1 to 5.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (Styrene-based copolymer) The styrene-based monomer in the present invention is an aromatic hydrocarbon substituted with a vinyl derivative excluding an α-substituted styrene-based monomer described later, and specific examples thereof include styrene and m-methylstyrene. , P-methylstyrene, vinyl naphthalene and the like. Of these, styrene is preferred from the viewpoint of availability and polymer properties. These may be used alone or in combination of two or more.

The α-substituted styrene monomer in the present invention is a compound in which a substituent is bonded to the α-position of the styrene monomer, specifically, α-methylstyrene, α-ethylstyrene, α-ethylstyrene, -Methyl-o-methylstyrene, α-methyl-m-methylstyrene, α-methyl-p-methylstyrene, α-methyl-vinylnaphthalene and the like. Among them, α-
Methylstyrene is preferred. These may be used alone or in combination of two or more.

The conjugated diene monomer in the present invention is a cyclic or chain hydrocarbon having a conjugated diene structure, and specifically, 1,3-cyclopentadiene, 1,3-cyclopentadiene,
Cyclohexadiene, 1,3-cycloheptadiene,
Cyclic conjugated dienes such as 1,3-cyclooctadiene and derivatives thereof, 1,3-butadiene, isoprene,
1,3-pentadiene, 1,3-hexadiene, 2,3
And chain conjugated dienes such as -dimethyl 1,3-butadiene. Among them, 1,3-cyclohexadiene, from the viewpoint of reactivity, polymer properties, and availability,
1,3-butadiene or isoprene is preferred,
1,3-butadiene or isoprene is particularly preferred. These may be used alone or in combination of two or more.

The styrenic copolymer in the present invention can be obtained, for example, by polymerizing the above-mentioned monomer at a temperature of preferably 40 to 70 ° C. The polymerization method will be described in detail later. For example, by keeping the temperature within this range, a copolymer having substantially no long chain chain of units derived from an α-substituted styrene monomer can be synthesized.

Here, the fact that the unit derived from the α-substituted styrene-based monomer has substantially no long-chain chain means that, for example, a 13C-NMR spectrum (68 MHz) of the styrene-based polymer measured in deuterated chloroform at room temperature. ) Can be confirmed. That is, when there is a long-chain chain of a unit derived from an α-substituted styrene monomer, δ149 to 15 in the 13C-NMR spectrum
At 1 ppm, a signal attributable to the ipso carbon of the aromatic ring is observed, whereas when there is no long-chain chain of the unit derived from the α-substituted styrene monomer, the similar signal is at δ149 ppm or less. Observed in the region of chemical shift values.

In the present invention, the styrene-based copolymer is composed of x% by weight of units derived from a styrene-based monomer, y% by weight of units derived from an α-substituted styrene-based monomer, and z% by weight of units derived from a conjugated diene monomer ( Where x, y and z are 42 ≦ x ≦ 95, 3
≦ y ≦ 40, 0 ≦ z ≦ 30, x + y + z = 100, 0.
The relationship of 05 ≦ y / (x + y) ≦ 0.40 is satisfied. )
Consists of If the unit derived from the α-substituted styrene monomer is too small, the effect of improving the heat distortion temperature by introducing the α-substituted styrene monomer cannot be obtained, and if it is too large, the effect of improving the heat deformation temperature can be obtained. However, the breaking reaction of the molecular chain during the hydrogenation reaction becomes intense and the toughness of the resin is lowered, which is not preferable. Further, the introduction of a unit derived from a conjugated diene monomer has the advantage of improving the toughness, but also has the disadvantage of reducing the thermal deformation temperature. In consideration of the balance between the two, the unit derived from the conjugated diene monomer must be suppressed to 30% by weight. More preferably 50
≦ x ≦ 90, preferably 60 ≦ x ≦ 90; 8 ≦ y ≦ 3
5, preferably 15 ≦ y ≦ 35; 0 ≦ z ≦ 20, preferably 0 ≦ z ≦ 10; x + y + z = 100; 0.10 ≦ y
/(X+y)≦0.35.

The bonding structure of the units derived from the monomers in the styrenic copolymer is as described above (there is no long-chain chain of the α-substituted styrene monomer, and the units derived from each monomer are within the above range). ) Is not particularly limited,
Specific examples include the following structural units.

(1) a block type structural unit composed of a unit derived from a styrene monomer, (2) a block type structural unit composed of a unit derived from a conjugated diene monomer, and (3) a unit derived from a styrene type monomer. And a taper type structural unit composed of a unit derived from an α-substituted styrene monomer, (4) a random type structural unit composed of a unit derived from a styrene monomer and a unit derived from an α-substituted styrene monomer, (5) Tapered structural unit consisting of a unit derived from a styrene monomer and a unit derived from a conjugated diene monomer,
(6) a random structural unit composed of a unit derived from a styrene monomer and a unit derived from a conjugated diene monomer, a taper type composed of a unit derived from a conjugated diene monomer and a unit derived from an α-substituted styrene monomer. Structural unit, random type structural unit consisting of a unit derived from a conjugated diene monomer and a unit derived from an α-substituted styrene monomer, (9) a unit derived from a styrene monomer, α
Tapered structural unit composed of a unit derived from a substituted styrene monomer and a unit derived from a conjugated diene monomer, (10) a unit derived from a styrene monomer, a unit derived from an α-substituted styrene monomer, and a conjugated diene A random structural unit consisting of units derived from monomers. Of these structural units, the units derived from α-substituted styrenic monomers are introduced to a minimum, so that the heat distortion temperature can be improved to the maximum. The copolymer preferably contains a structural unit, and more preferably the structural unit (3) in view of ease of synthesis. In addition, it is preferable to include the structural unit of (2) as a structure for maximizing the effect of improving toughness by introducing a conjugated diene to a minimum and further minimizing a decrease in heat distortion temperature.

These structural units are present in one molecule of the copolymer.
Although it may be repeated about 10 times, as a preferred copolymer structure, a copolymer consisting of (3), a copolymer consisting of-(2), a copolymer consisting of-(2)-, (2 ) −− (2)
And a copolymer consisting of

The structure of the styrene copolymer is preferably a chain or star-branched structure. The star-branched structure has the advantage that the fluidity is improved as compared with the chain structure in comparison with the molecular weight, and the moldability is improved.

The molecular weight is preferably set to an appropriate value depending on the application to be used. However, as a value in terms of polystyrene (number average molecular weight) measured by a GPC (gel permeation chromatography) method, 2
0.00-1,000,000, preferably 30,0
00 to 800,000, more preferably 40,000 to
Preferably it is in the range of 700,000.

(Production of Styrene-Based Copolymer) The styrene-based copolymer of the present invention comprises a styrene-based monomer, an α-substituted styrene-based monomer and, if necessary, a conjugated diene monomer at a temperature of 40.degree. Manufactured by polymerizing at ~ 70 ° C. It is considered that by keeping the polymerization temperature at such a temperature, it is possible to synthesize a copolymer having substantially no long-chain chains derived from α-substituted styrene-based monomers.
Hereinafter, this point will be described in detail.

With respect to α-substituted styrene-based monomers represented by α-methylstyrene, reference is made to H.-M. W. McCormic
k, J. et al. Poly. Sci. , 25 volumes, 488-490
As reported on page (1957), it is known that a depolymerization reaction, which is a reverse reaction, occurs during the homopolymerization reaction. Generally, the depolymerization reaction occurs preferentially as the temperature rises, and the polymerization reaction does not proceed at a temperature higher than the temperature at which the polymerization reaction rate and the depolymerization reaction rate match, that is, the so-called ceiling temperature.
However, the depolymerization reaction is a phenomenon that occurs only when a chain of α-substituted styrene-based monomers is generated. For example, a bond of α-substituted styrene-based monomer-styrene-based monomer-α-substituted styrene-based monomer is used. Then, depolymerization does not proceed. By utilizing this property, for example, by controlling the reaction temperature, a styrene copolymer having no long-chain chain of the α-substituted styrene monomer can be synthesized. For example, when styrene and α-methylstyrene are copolymerized, since the ceiling temperature of α-methylstyrene is 61 ° C., polymerization is performed at a temperature around this temperature until the styrene monomer is depleted, thereby obtaining α-methylstyrene.
A copolymer having almost no long chain of methylstyrene can be produced.

If the reaction temperature is too low, a long chain chain derived from the α-substituted styrene monomer tends to be formed. As a result, during the hydrogenation reaction, a molecular chain scission reaction is likely to occur,
Not preferred. On the other hand, if the reaction temperature is too high, the active terminal at the time of polymerization is thermally decomposed, and the polymerization reaction is stopped. Here, thermal decomposition means
This is completely different from the above-mentioned depolymerization reaction. That is, in the case of the depolymerization reaction, the active terminal is alive only by the elimination of the monomer, whereas the thermal decomposition is a reaction of the active terminal itself, for example, in the case of anionic polymerization with a lithium compound, A elimination reaction of lithium hydride from the terminal anionic lithium, and as a result, the active terminal is inactivated and the polymerization reaction does not proceed.

The styrenic copolymer is anionic polymerized,
Although it can be produced by a conventionally known method such as radical polymerization, cationic polymerization, and coordination polymerization, it is preferable to use an anionic polymerization technique from the viewpoint that the structure can be easily controlled.

Examples of the initiator for the polymerization using the anionic polymerization technique include metals of Groups 1 and 2 of the periodic table and their organometallic compounds. In particular,
Lithium, sodium, potassium, rubidium, cesium, francium, magnesium, calcium, strontium, barium, radium, methyl lithium, ethyl lithium, n-propyl lithium, iso-propyl lithium, n-butyl lithium, iso-butyl lithium, sec- Butyl lithium, cyclopentadienyl lithium, phenyl lithium, cyclohexyl lithium, methyl sodium, ethyl sodium, n-propyl sodium, iso-propyl sodium, n-butyl sodium, cyclopentadienyl sodium, dimethylmagnesium, bis (cyclopentadiene Enyl) magnesium, dimethyl calcium, bis (cyclopentadienyl) calcium, and the like. Of these, organolithium compounds are preferred in terms of availability and operability, and n-butyllithium and sec-butyllithium are particularly preferred. These may be used alone,
Two or more types may be combined.

In conducting the anionic polymerization, an electron-donating compound may be added for the purpose of further activating the above-mentioned initiator and improving the reaction rate, increasing the molecular weight and preventing the anion from being deactivated. The electron donating compound is a compound that can donate electrons to the metal of the initiator without impairing the function of the initiator, and is a compound containing an oxygen atom, a nitrogen atom, a sulfur atom, and a phosphorus atom. Specifically, furans, tetrahydrofuran, diethyl ether, anisole, diphenyl ether, methyl-t-butyl ether, dioxane, dioxolan, dimethoxyethane, ethers such as diethoxyethane, trimethylamine, triethylamine, tributylamine, tetramethylmethylenediamine, tetramethyl Ethylenediamine, tetraethylmethylenediamine, tetraethylethylenediamine, tetramethyl1,
Tertiary amines such as 3-propanediamine, tetramethylphenylenediamine, diazabicyclo [2,2,2] octane, thioethers such as dimethylsulfide, thiophene and tetrahydrothiophene, trimethylphosphine, triethylphosphine, tri-n-butylphosphine; Tertiary phosphines such as triphenylphosphine, dimethylphosphinomethane, dimethylphosphinoethane, dimethylphosphinopropane, diphenylphosphinomethane, diphenylphosphinoethane, diphenylphosphinopropane, sodium-t-butoxide, sodium-phenoxide, Metal alkoxides such as potassium-t-butoxide and potassium-phenoxide can be mentioned. Of these, particularly preferred are tetrahydrofuran, dimethoxyethane, tetramethylethylenediamine, and diazabicyclo [2,2,2] octane. These may be used alone or in combination of two or more.

The amount of the electron-donating compound to be added depends on the type of the initiator and the electron-donating compound.
0.1 to 100 mol, preferably 0.2 to 100 mol
It is 50 mol, more preferably 0.3 to 10 mol. If the amount is too small, the activating effect cannot be obtained, and if the amount is too large, the activating effect does not increase, and the electron donating compound is wasted.
However, this does not apply when an electron donating compound is used as a solvent.

The styrenic copolymer in the present invention can be synthesized by using solution polymerization or bulk polymerization. The solvent used in the synthesis by solution polymerization is not particularly limited as long as it dissolves the polymer and does not deactivate the active terminal during the polymerization. Preferred examples thereof include butane, n-pentane, n-hexane, C such as n-heptane
4 to 12 aliphatic hydrocarbons; C4 to 12 alicyclic hydrocarbons such as cyclobutane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, and decalin; benzene, toluene, xylene, mesitylene; C such as ethylbenzene, diethylbenzene, cumene, tetralin, naphthalene, etc.
C4 to C6 such as aromatic hydrocarbons of 6 to 12, diethyl ether, tetrahydrofuran, methyl-t-butyl ether, etc.
And 12 ethers. Of these, aliphatic hydrocarbons, alicyclic hydrocarbons, and ethers are preferred, and cyclohexane, methylcyclohexane, and methyl-t-butyl ether are particularly preferred.

The reaction conditions other than the temperature during the polymerization are not particularly limited because they vary depending on the polymerization method and the like, but the reaction time is usually 5 minutes to 20 hours, preferably 10 minutes to 15 hours, more preferably 20 minutes to 1
0 hours. In addition, since the active end may be very sensitive to water, oxygen, etc. during the polymerization reaction, the reaction is carried out under an inert atmosphere such as nitrogen or argon, and in an environment where reagents, solvents, and inert gases are sufficiently dehydrated. Is preferred.

By further adding a coupling agent to the copolymer obtained by the above method, a copolymer in which the copolymer is bonded in a chain or star-shaped branch can be synthesized. Examples of the coupling agent used here include halogenated silanes such as dimethyldichlorosilane, methyltrichlorosilane, tetrachlorosilane and tetrabromosilane, dimethyldimethoxysilane, methyltrimethoxysilane, tetramethoxysilane, bis (trimethoxysilyl) methane, Bis (trimethoxysilyl) ethane,
Alkoxysilanes such as dimethyldiethoxysilane, methyltriethoxysilane, tetraethoxysilane, bis (triethoxysilyl) methane, bis (triethoxysilyl) ethane and tetraphenoxysilane, allyloxysilanes, α, α'-dichloro Halides such as xylene, α, α'-dibromoxylene, tetrakis (chloromethyl) benzene, tetrakis (bromolomethyl) benzene, and esters such as dimethyl oxalate, dimethyl succinate, dimethyl glutarate, dimethyl phthalate, dimethyl terephthalate And the like.

More specifically, the following method can be mentioned as a method for synthesizing the styrenic polymer. (1) A method of polymerizing in the presence of a styrene monomer. By this method, a block-type structural unit composed of a unit derived from a styrene-based monomer can be formed. (2) A method of polymerizing in the presence of a conjugated diene monomer. By this method, a block-type structural unit composed of a unit derived from a conjugated diene monomer can be formed. (3) A method of polymerizing in the presence of a styrene monomer and an α-substituted styrene monomer. Generally, an α-substituted styrene monomer is harder to polymerize than a styrene monomer.
A tapered structural unit composed of a unit derived from a substituted styrene monomer can be formed.

(4) A method in which polymerization is carried out while the concentration ratio between the styrene monomer and the α-substituted styrene monomer is always kept constant.
According to this method, a random structural unit composed of a unit derived from a styrene monomer and a unit derived from an α-substituted styrene monomer can be formed. (5) A method of polymerizing in the presence of a styrene monomer and a conjugated diene monomer. In general, a styrene-based monomer is harder to polymerize than a conjugated diene monomer, so that a taper-type structural unit composed of a unit derived from a styrene-based monomer and a unit derived from a conjugated diene monomer is formed by this method. Can be. (6)
A method in which polymerization is carried out while the concentration ratio between the styrene monomer and the conjugated diene monomer is always kept constant. By this method, a random structural unit composed of a unit derived from a styrene monomer and a unit derived from a conjugated diene monomer can be formed.

A method of polymerizing in the presence of a conjugated diene monomer and an α-substituted styrene monomer. In general, α-substituted styrene monomers are much more difficult to polymerize than conjugated diene monomers. Therefore, according to this method, when the charged amount of the α-substituted styrene is as large as about 100 mol times or more as compared with the conjugated diene monomer, it is composed of the unit derived from the conjugated diene monomer and the unit derived from the α-substituted styrene monomer. A tapered structural unit can be formed. When the α-substituted styrene is lower than that, the α-substituted styrene-based monomer hardly polymerizes, and a structural unit substantially consisting of a unit derived from a conjugated diene copolymer can be formed.

A method in which the polymerization is carried out while the concentration ratio between the conjugated diene monomer and the α-substituted styrene monomer is always kept constant. According to this method, when the charged amount of the α-substituted styrene is as large as about 100 mol times or more as compared with the conjugated diene monomer, a random unit composed of a unit derived from the conjugated diene monomer and a unit derived from the α-substituted styrene monomer is used. A mold structural unit can be formed. When the α-substituted styrene is lower, α
The substituted styrene-based monomer hardly polymerizes, and can form a structural unit substantially consisting of a unit derived from a conjugated diene copolymer.

(9) A method of polymerizing in the presence of a styrene monomer, a conjugated diene monomer and an α-substituted styrene monomer. Generally, the polymerization reactivity is conjugated diene monomer, styrene-based monomer, α-substituted styrene-based monomer in descending order.
A tapered structural unit composed of a unit derived from a styrene monomer and a unit derived from an α-substituted styrene monomer can be formed. (10) A method in which polymerization is carried out while always keeping the concentration ratio of the styrene monomer, the conjugated diene monomer and the α-substituted styrene monomer constant. By this method, a random structural unit composed of a unit derived from a styrene monomer, a unit derived from an α-substituted styrene monomer, and a unit derived from a conjugated diene monomer can be formed. When using the method of anionic polymerization, by sequentially using the above method,
A polymer in which each structural unit is bonded can be obtained. Further, by adding the above-mentioned coupling agent to the polymer obtained by these methods, a star-shaped branched copolymer can be synthesized.

Among these methods, (3) and / or the point that the unit derived from the α-substituted styrenic monomer can be minimized to maximize the heat distortion temperature.
Alternatively, the method preferably includes the method (4), and more preferably includes the method (3) in view of ease of synthesis. In addition, as a method of introducing a structure that maximizes the effect of improving toughness by introducing a conjugated diene to a minimum and further minimizes a decrease in heat distortion temperature, (2) and / or
It is preferable to include the method of (7).

The charge ratio of the monomers when forming such a structural unit may be appropriately determined according to the ratio of the units derived from each monomer contained in the intended styrene-based copolymer. Not limited. However, in general, styrene-based monomers and conjugated diene monomers are incorporated into the copolymer according to the charge ratio of the monomers, but the α-substituted styrene-based monomer has low reactivity, so it is charged. Not all monomers are incorporated into the polymer. Therefore,
It is preferable to add the α-substituted styrene monomer to the polymerization system in an amount of about 1 to 1000 times the amount incorporated in the polymer.
More preferably 2-500 times, even more preferably 3-
It is 300 times.

(Hydrogenated styrene-based copolymer) In the present invention, the styrene-based copolymer is treated in the presence of a hydrogenation catalyst.
In a hydrogenation reaction, the aromatic ring and the carbon-carbon double bond contained in the copolymer are hydrogenated to obtain a hydrogenated styrene copolymer.

The hydrogenation catalyst in the present invention is not particularly limited as long as it can hydrogenate the aromatic ring and the carbon-carbon double bond contained in the styrenic copolymer. , Palladium, platinum,
Examples thereof include solid catalysts supported on a porous carrier such as carbon, alumina, silica, silica alumina, and diatomaceous earth, such as noble metals such as cobalt, ruthenium, and rhodium, and oxides, salts, and complexes thereof. Among them, those in which nickel, palladium, platinum, and ruthenium are supported on alumina, silica, silica alumina, and diatomaceous earth exhibit high reactivity and are preferably used. Such a hydrogenation catalyst may be used in an amount of 0.5 to 40, based on the catalytic activity, based on the copolymer.
It is preferable to use it in the range of weight%.

[0052] The hydrogenation reaction is usually carried out in the presence of a solvent. The hydrogenation reaction may be performed after once isolating the polymer after the polymerization reaction.However, when the polymerization is performed using a solution polymerization method, the polymerization solution is used as it is, or a necessary solvent is added. It is also possible to carry out. Such a solvent is preferably selected in consideration of the hydrogenation catalytic ability, the presence or absence of side reactions such as molecular chain scission, the solubility of the polymer before and after the hydrogenation reaction, and the like. Specifically, butane, n-pentane, n
-C4-12 aliphatic hydrocarbons such as hexane and n-heptane; C4-12 such as cyclobutane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane and decalin.
And C4-12 ethers such as diethyl ether, tetrahydrofuran and methyl-t-butyl ether. Of these, cyclohexane, methylcyclohexane, and methyl-t-butyl ether are particularly preferred, though depending on the type of catalyst. In addition, polar solvents such as esters and alcohols are added to the above-mentioned solvents within a range not hindering the solubility of the polymer, for the purpose of increasing the activity of the reaction, or suppressing the molecular weight reduction due to molecular chain breakage due to hydrogenolysis. You may.

In the present invention, it is preferable to carry out the hydrogenation reaction in the above-mentioned solvent system at a styrene copolymer concentration of 3 to 50% by weight. If the concentration of the copolymer is less than 3% by weight, it is not preferable in terms of productivity and economy, and 50% by weight.
If it exceeds, the solution viscosity is too high, which is not preferable in terms of handling and reactivity.

The hydrogenation reaction conditions depend on the catalyst used, but are usually 3 to 25 MPa in hydrogen pressure and 70 to 220 in reaction temperature.
It is performed within the range of ° C. If the reaction temperature is too low, the reaction hardly proceeds, and if the reaction temperature is too high, the molecular weight is likely to be reduced by hydrogenolysis, which is not preferable. In order to prevent a decrease in molecular weight due to molecular chain breakage and to promote the reaction smoothly, hydrogen is applied at an appropriate temperature and hydrogen pressure appropriately determined according to the type and concentration of the catalyst used, the concentration of the copolymer solution, the molecular weight, and the like. It is preferable to carry out a chemical reaction.

Further, the degree of hydrogenation of the hydrogenated styrene-based copolymer is determined by the hydrogenation rate = ｛1- (the number of moles of aromatic ring contained per mole of copolymer after hydrogenation) / (hydrogen Moles of aromatic ring contained per mole of copolymer before polymerization)｝
When expressed using an index of x100 (%) (calculated using ¹ H-NMR spectrum), the hydrogenation rate of the hydrogenated styrene-based copolymer used in the present invention is 90 to 10
0%, preferably 95-100%, more preferably 98
It is preferably from 100% to 100%. If the hydrogenation rate is too low, the transparency and the physical heat resistance of the copolymer decrease, which is not preferable. The hydrogenation of the carbon-carbon double bond contained in the unit derived from the conjugated diene monomer is much more likely to occur than the hydrogenation of the aromatic ring. And the carbon-carbon double bond contained in the unit derived from the chain monomer is substantially completely hydrogenated.

After the completion of the hydrogenation reaction, the catalyst can be removed by a known post-treatment method such as centrifugation or filtration. In the present invention used for optical material applications, it is necessary to reduce the residual catalyst metal component in the resin as much as possible, and the amount of the residual metal catalyst is preferably 10 ppm or less, more preferably 1 ppm or less, and even more preferably 5 ppm or less.
00 ppb or less. In particular, in the present invention, among the residual metal catalysts, it is preferable to use a hydrogenated styrene copolymer having a transition metal content of 10 ppm or less, more preferably 5 ppm or less. From the polymer solution from which the hydrogenation catalyst has been removed, the target hydrogenated styrene-based copolymer can be obtained by a method such as evaporation of the solvent, stripping, or reprecipitation.

The molecular weight of the hydrogenated styrenic copolymer thus obtained is preferably set to an appropriate value depending on the intended use. However, the value in terms of polystyrene measured by GPC (gel permeation chromatography) is preferred. (Number average molecular weight) 20,000 to 1,
1,000,000, preferably 30,000-800,0
00, more preferably 40,000 to 700,000. If the molecular weight is too small, moldability is improved, but toughness and heat resistance are unfavorably reduced. If the molecular weight is too large, toughness and heat resistance are improved, but moldability is undesirably reduced.

The molecular weight distribution of the hydrogenated styrene copolymer in the present invention is preferably 4.0 or less. More preferably, it is 3.5 or less. The molecular weight distribution is the value of (weight average molecular weight) / (number average molecular weight) calculated from the molecular weight in terms of polystyrene measured by the GPC method. If the molecular weight distribution is too large, the toughness and the heat distortion temperature are too low, which is not preferable.

The thermal deformation temperature of the hydrogenated styrenic copolymer of the present invention becomes higher as a result of introducing a unit derived from an α-substituted styrene monomer, as compared with a case where the unit is not introduced, and is 100 to 180 °. C. is preferred. More preferably, it is 105 to 170 ° C. Here, the heat distortion temperature is a value measured according to JIS K7206.

The hydrogenated styrene-based copolymer obtained in the present invention may be used as a blend of the copolymer having a different molecular weight or a composition with another polymer according to the purpose. Other polymers include, for example, hydrogenated styrenic polymers described in JP-A-63-4391,
And a hydrogenated styrene-based hydrocarbon-conjugated diene-based hydrocarbon copolymer described in 116442.

The hydrogenated styrene copolymer of the present invention includes:
In order to improve thermochemical stability during melt molding or to prevent autoxidation, Irganox 1010,
A hindered phenol stabilizer such as 1076 (manufactured by Ciba-Geigy), a phosphine stabilizer such as Irgafos 168 (manufactured by Ciba-Geigy), or an addition-type stabilizer such as Sumilizer GM and Sumilizer GS (manufactured by Sumitomo Chemical) are added. Is preferred. If necessary, release agents such as long-chain aliphatic alcohols and long-chain aliphatic esters, and other additives such as lubricants, plasticizers, ultraviolet absorbers, and antistatic agents can be added.

The optical material of the present invention can be formed by a known method such as injection molding, injection compression molding, extrusion molding, and solution casting. In particular, it can be suitably used for manufacturing optical disk substrates or optical lenses by injection molding or injection compression molding. In molding such an optical disk, the resin temperature is 250 to 380 ° C., preferably 270 to 380 ° C.
The range of 50 ° C, more preferably 280-340 ° C is used, and the mold temperature is 40-140 ° C, preferably 60-140 ° C.
130 ° C, more preferably 70-120 ° C.

[0063]

According to the present invention, a styrene copolymer containing a styrene monomer unit, an α-substituted styrene monomer unit and, if necessary, a unit derived from a conjugated diene monomer is hydrogenated. The obtained hydrogenated styrenic copolymer and optical material are provided. This hydrogenated copolymer has excellent physical heat resistance, mechanical properties, and moldability, in addition to the inherent properties of conventional resins, such as transparency. Therefore, it is suitable as an optical material such as an optical disc substrate. Can be used.

[0064]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to these examples.

(Reagents and Solvents) Styrene, α-methylstyrene, isoprene and p-methylstyrene were purified by distillation from calcium hydride and used after being sufficiently dried. As cyclohexane and methyl-t-butyl ether, dehydrated grades were purchased, and 4A molecular sieves were further added thereto, and those sufficiently dried were used.

As n-butyllithium and sec-butyllithium, commercially available cyclohexane solutions were used as they were. Nickel / silica alumina (nickel carrying rate 65
%) Was purchased from Aldrich and used as is.

(Measurement of physical properties) Number average molecular weight: Gel permeation chromatography (GPC, Syodex System, manufactured by Showa Denko KK)
The molecular weight was determined by em-11) using tetrahydrofuran as a solvent, and the molecular weight in terms of polystyrene was determined.

Presence or absence of long chain of α-methylstyrene: J
Using an EOL JNR-EX270 type nuclear magnetic resonance absorption apparatus, 13C-NMR measurement of the polymer before hydrogenation was conducted to determine the chemical shift value of the ipso carbon of the aromatic ring, and δ
The presence or absence of a signal in the region of 149 to 151 ppm was examined. Deuterated chloroform was used as a solvent.

Hydrogenation rate: JEOL JNR-EX270
Hydrogenation = 1- (number of moles of aromatic ring contained in 1 mole of copolymer after hydrogenation) / (copolymerization before hydrogenation) by ¹ H-NMR measurement using a nuclear magnetic resonance absorption apparatus. The number of moles of aromatic ring contained in 1 mole of the compound)｝ x100 (%) was determined.

Residual metal content in resin: Quantified by ICP emission spectrometry. Glass transition temperature (Tg): TA Instrument
The measurement was performed at 20 ° C./min using a 2920 type DSC manufactured by s Corporation. Heat distortion temperature: Measured according to JIS K7206.

Example 1 154 g of styrene and α-
406 g of methylstyrene and 869 g of cyclohexane were charged. After heating the solution to 40 ° C, 1.3 mL of a 1.6 Mn-butyllithium-hexane solution was added, the polymerization temperature was raised to 55 ° C, and the reaction was performed for 1.5 hours. afterwards,
0.8 g of isopropanol was added to terminate the polymerization, and the resulting solution was poured into an excess of isopropanol to cause reprecipitation. The obtained white solid was dried with a heating and reduced pressure drier to obtain styrene-
An α-methylstyrene copolymer was obtained.

The number average molecular weight determined by GPC was 162,
000, molecular weight distribution was 1.20. Also, ¹ H-N
The weight ratio of styrene / α-methylstyrene determined by MR was 82/18. In the 13C-NMR spectrum, a signal attributable to the ipso carbon of the aromatic ring was observed at δ144 to 148 ppm,
No signal was observed between 9 and 151 ppm. Therefore, it was found that there was no long-chain chain of α-methylstyrene.

This copolymer was prepared using cyclohexane 3000
g, methyl-t-butyl ether 700 g, nickel / silica alumina 30 g was added, hydrogen pressure 10MP
a, A hydrogenation reaction was performed at a temperature of 180 ° C. for 4 hours. The solution was taken out of the autoclave and subjected to pressure filtration using a membrane filter having a pore size of 0.1 μm, whereby a colorless and transparent solution was obtained.

The solution was added to Sumilizer GS as a stabilizer.
Was added to the polymer in an amount of 0.3% by weight, and the mixture was concentrated under reduced pressure and flushed, and the solvent was distilled off to obtain a blockless colorless and transparent hydrogenated styrene-α-methylstyrene copolymer.

The hydrogenation rate determined from ¹ H-NMR is 100
%was. The number average molecular weight was 63,000, and the molecular weight distribution was 1.82. According to ICP emission spectroscopy, the amount of residual catalytic metal in the resin was 0.8 ppm for Ni,
Al was 0.4 ppm, Si was 0.5 ppm, and both were 1
ppm or less. The glass transition temperature measured by DSC was 165 ° C., and the heat distortion temperature of the molded product was 12 ° C.
It was 6 ° C.

Example 2 190 g of styrene and α-
940 g of methylstyrene and 670 g of cyclohexane were charged. After heating the solution to 40 ° C, 1.7 mL of a 1.6 Mn-butyllithium-hexane solution was added, the polymerization temperature was raised to 55 ° C, and the reaction was performed for 1.5 hours. afterwards,
0.8 g of isopropanol was added to terminate the polymerization, and the resulting solution was poured into an excess of isopropanol to cause reprecipitation. The obtained white solid was dried with a heating and reduced pressure drier to obtain styrene-
An α-methylstyrene copolymer was obtained.

The number average molecular weight determined by GPC is 198,
000, molecular weight distribution was 1.25. Also, ¹ H-N
The weight ratio of styrene / α-methylstyrene determined from MR was 70/30. In the 13C-NMR spectrum, a signal attributable to the ipso carbon of the aromatic ring was observed at δ144 to 149 ppm,
No signal was observed between 9 and 151 ppm. Therefore, it was found that there was no long-chain chain of α-methylstyrene.

This copolymer was prepared using cyclohexane 3000
g, methyl-t-butyl ether 700 g, nickel / silica alumina 30 g was added, hydrogen pressure 10MP
a, A hydrogenation reaction was performed at a temperature of 180 ° C. for 4 hours. The solution was taken out of the autoclave and subjected to pressure filtration using a membrane filter having a pore size of 0.1 μm, whereby a colorless and transparent solution was obtained.

The solution was added to Sumilizer GS as a stabilizer.
Was added to the polymer in an amount of 0.3% by weight, and the mixture was concentrated under reduced pressure and flushed, and the solvent was distilled off to obtain a blockless colorless and transparent hydrogenated styrene-α-methylstyrene copolymer.

The hydrogenation rate determined from ¹ H-NMR is 100
%was. The number average molecular weight is 75,000,
The molecular weight distribution was 2.10. According to ICP emission spectral analysis, the amount of residual catalyst metal in the resin was 0.8 pp for Ni.
m and Al were 0.4 ppm and Si were 0.7 ppm, all of which were 1 ppm or less. The glass transition temperature measured by DSC was 169 ° C, and the heat distortion temperature of the molded product was 131 ° C.

Example 3 In a stainless steel autoclave which had been sufficiently dried and purged with nitrogen, 85 g of styrene, 218 g of α-methylstyrene and 498 g of cyclohexane were charged. After heating the solution to 40 ° C, 2.3 mL of a 1.6 Mn-butyllithium-hexane solution was added, the polymerization temperature was raised to 55 ° C, and the reaction was performed for 0.5 hour. Subsequently, 22 g of isoprene and 98 g of cyclohexane were added to this solution and reacted at 50 ° C. for 2.5 hours. Thereafter, 67 g of styrene, 25 g of α-methylstyrene, and 196 g of cyclohexane were added, and reacted at 55 ° C. for 1 hour. Thereafter, 0.8 g of isopropanol was added to stop the polymerization, and the resulting solution was poured into an excess of isopropanol to cause reprecipitation.

The obtained white solid was dried with a heating and drying oven to obtain a styrene-α-methylstyrene-isoprene copolymer. The structure is (copolymer of styrene and α-methylstyrene)-(block copolymer of isoprene)-
(Copolymer of styrene and α-methylstyrene).

The number average molecular weight determined by GPC is 100,
000, molecular weight distribution was 1.21. Also, ¹ H-N
The weight ratio of styrene / α-methylstyrene / isoprene determined from MR was 67/24/9. Also, 13C-
In the NMR spectrum, a signal attributable to the ipso carbon of the aromatic ring was observed at δ 144 to 149 ppm, and no signal was observed at δ 149 to 151 ppm. Therefore, it was found that there was no long-chain chain of α-methylstyrene. 3000 g of cyclohexane and 700 g of methyl-t-butyl ether
g, and add 30 g of nickel / silica alumina,
The hydrogenation reaction was performed at a hydrogen pressure of 10 MPa and a temperature of 180 ° C. for 4 hours. The solution was taken out of the autoclave and the pore size was adjusted to 0.
When pressure filtration was performed using a 1 μm membrane filter, a colorless and transparent solution was obtained.

The solution was added as a stabilizer to Sumilizer GS.
Was added to the polymer in an amount of 0.3% by weight, followed by concentration under reduced pressure and flashing, and the solvent was distilled off to obtain a massive colorless and transparent hydrogenated styrene-α-methylstyrene-isoprene copolymer.

The hydrogenation rate determined from ¹ H-NMR was 100
%was. In addition, the number average molecular weight was 45000, and the molecular weight distribution was 1.80. According to ICP emission spectroscopy, the amount of residual catalyst metal in the resin was 0.9 ppm for Ni,
Al was 0.5 ppm, Si was 0.3 ppm, and both were 1
ppm or less. The glass transition temperature measured by DSC was 161 ° C., and the heat distortion temperature of the molded product was 11 ° C.
It was 9 ° C.

Comparative Example 1 In a stainless steel autoclave purged with nitrogen, 500 g of polystyrene having a number average molecular weight of 170,000 and a molecular weight distribution of 2.20, 3300 g of cyclohexane, 700 g of methyl-t-butyl ether,
80 g of nickel / silica alumina is added, and the hydrogen pressure is 10 M
The hydrogenation reaction was performed at Pa and a temperature of 180 ° C. for 8 hours. The solution was taken out of the autoclave and subjected to pressure filtration using a membrane filter having a pore size of 0.1 μm, whereby a colorless and transparent solution was obtained. To this solution was added 0.3% by weight of Sumilizer GS as a stabilizer relative to the polymer, and the mixture was concentrated under reduced pressure and flushed to distill off the solvent to obtain a massive colorless and transparent hydrogenated styrene polymer. ^The degree of hydrogenation determined from ¹ H-NMR was 99.9%. The number average molecular weight was 150,000, and the molecular weight distribution was 2.30. The glass transition temperature measured by DSC is 1
The molded product had a heat deformation temperature of 117 ° C.

Comparative Example 2 266 g of styrene and 2500 g of cyclohexane were charged into a stainless steel autoclave which had been sufficiently dried and purged with nitrogen. After heating the solution to 40 ° C, 3.5 mL of a 1.0 Mn-butyllithium-hexane solution was added, heated to 50 ° C, and reacted for 2 hours. Next, 60 g of isoprene was added as a cyclohexane solution, and the mixture was further reacted for 2 hours. Subsequently, 266 g of styrene and 700 g of cyclohexane were added and reacted for 2 hours. After the completion of the reaction, 0.7 g of isopropanol was added to obtain a styrene-isoprene-styrene block copolymer. The number average molecular weight determined by GPC is 107,0
00 and the molecular weight distribution was 1.25. ¹ H-NM
The weight ratio of styrene / isoprene determined from R is 90/1.
It was 0.

To this solution, 1300 g of cyclohexane, 700 g of methyl-t-butyl ether and 80 g of nickel / silica alumina were added, and a hydrogen pressure of 10 MPa and a temperature of 180 ° C.
For 4 hours. The solution was taken out of the autoclave and subjected to pressure filtration using a membrane filter having a pore size of 0.1 μm, whereby a colorless and transparent solution was obtained. To this solution was added 0.3% by weight of Sumilizer GS as a stabilizer relative to the polymer, followed by concentration under reduced pressure and flashing, and the solvent was distilled off to obtain a massive colorless and transparent hydrogenated styrene-isoprene copolymer. Obtained.

The hydrogenation rate determined from ¹ H-NMR is 100
%was. The number average molecular weight determined by GPC is 6
It was 8,000 and the molecular weight distribution was 1.25. The glass transition temperature measured by DSC was 145 ° C, and the heat distortion temperature of the molded product was 89 ° C.

[Comparative Example 3] 250 g of styrene, α-
900 g of methylstyrene and 500 g of cyclohexane were charged. After heating the solution to 20 ° C, 3.5 mL of a 1.6 Mn-butyllithium-hexane solution was added, and the mixture was reacted for 4 hours while keeping the polymerization temperature at 20 ° C. Thereafter, 0.8 g of isopropanol was added to stop the polymerization, and the resulting solution was poured into an excess of isopropanol to cause reprecipitation. The obtained white solid was dried with a heating and drying oven to obtain a styrene-α-methylstyrene copolymer.

The number average molecular weight determined by GPC is 108,
000, molecular weight distribution was 1.33. Also, ¹ H-N
The weight ratio of styrene / α-methylstyrene determined by MR was 65/35. Further, in the 13C-NMR spectrum, a signal attributable to the ipso carbon of the aromatic ring was observed at δ145 to 150 ppm,
The signal was in the range of 9 to 151 ppm. Therefore, it was found that a long chain of α-methylstyrene was present.

The copolymer was treated with cyclohexane 3000
g, methyl-t-butyl ether (700 g), nickel / silica alumina (40 g) was added, and hydrogen pressure was set to 10MP.
a, A hydrogenation reaction was performed at a temperature of 180 ° C. for 4 hours. The solution was taken out of the autoclave and subjected to pressure filtration using a membrane filter having a pore size of 0.1 μm, whereby a colorless and transparent solution was obtained.

The solution was added as a stabilizer to Sumilizer GS.
Was added to the polymer in an amount of 0.3% by weight, and the mixture was concentrated under reduced pressure and flushed, and the solvent was distilled off to obtain a blockless colorless and transparent hydrogenated styrene-α-methylstyrene copolymer.
^The degree of hydrogenation determined from ¹ H-NMR was 100%. However, a severe cleavage reaction of the molecular chain occurred, and the number average molecular weight was 3,600 and the molecular weight distribution was 9.1. This copolymer was too brittle to be molded.

Example 4 A copolymer obtained in the same manner as in Example 1 was prepared at a cylinder temperature of 320.degree.
It was formed into a 6 mm disk. 100 ℃
And the groove depth of the disk was measured, and it was found that the groove depth was 99% of the groove depth before heating, and that the depth was almost maintained.

Example 5 A copolymer obtained in the same manner as in Example 3 was prepared at a cylinder temperature of 320.degree.
It was formed into a 6 mm disk. 100 ℃
And the groove depth of the disk was measured, and it was found that the groove depth was 99% of the groove depth before heating, and that the depth was almost maintained.

[Comparative Example 4] 80 g of styrene and 1250 g of α-methylstyrene were charged into a sufficiently dried and nitrogen-purged stainless steel autoclave. After heating the solution to 40 ° C., 1.8 mL of 1.6 Mn-butyllithium-hexane solution was added, and the polymerization temperature was heated to 55 ° C.
Allowed to react for hours. Thereafter, 0.8 g of isopropanol was added to stop the polymerization, and the resulting solution was poured into an excess of isopropanol to cause reprecipitation. The obtained white solid was dried with a heating and drying oven to obtain a styrene-α-methylstyrene copolymer.

The number average molecular weight determined by GPC is 158,
000, molecular weight distribution was 1.38. Also, ¹ H-N
The weight ratio of styrene / α-methylstyrene determined by MR was 51/49. In the 13C-NMR spectrum, a signal attributable to the ipso carbon of the aromatic ring was observed at δ 144 to 150 ppm, and δ 14
The signal was in the range of 9 to 151 ppm. Therefore, it was found that a long chain of α-methylstyrene was present.

This copolymer was prepared using cyclohexane 3000
g, methyl-t-butyl ether 700 g, nickel / silica alumina 30 g was added, hydrogen pressure 10MP
a, A hydrogenation reaction was performed at a temperature of 180 ° C. for 4 hours. The solution was taken out of the autoclave and subjected to pressure filtration using a membrane filter having a pore size of 0.1 μm, whereby a colorless and transparent solution was obtained.

The solution was added as a stabilizer to Sumilizer GS.
Was added to the polymer in an amount of 0.3% by weight, and the mixture was concentrated under reduced pressure and flushed, and the solvent was distilled off to obtain a blockless colorless and transparent hydrogenated styrene-α-methylstyrene copolymer.
^The degree of hydrogenation determined from ¹ H-NMR was 100%. However, a severe cleavage reaction of the molecular chain occurred, and the number average molecular weight was 15,000 and the molecular weight distribution was 6.3. This copolymer was too brittle to be molded.

[Comparative Example 5] 154 g of styrene and p-
100 g of methylstyrene and 976 g of cyclohexane were charged. After heating the solution to 40 ° C, 1.5 mL of a 1.6 Mn-butyllithium-hexane solution was added, the polymerization temperature was raised to 50 ° C, and the reaction was performed for 1.0 hour. afterwards,
0.8 g of isopropanol was added to terminate the polymerization, and the resulting solution was poured into an excess of isopropanol to cause reprecipitation.

The obtained white solid was dried with a heating and drying oven to obtain a styrene-p-methylstyrene copolymer. G
The number average molecular weight determined from PC was 180,000, and the molecular weight distribution was 1.31. The weight ratio of styrene / p-methylstyrene determined from ¹ H-NMR was 62/38. This copolymer was dissolved in 3000 g of cyclohexane and 700 g of methyl-t-butyl ether, and nickel /
30 g of silica alumina was added, and a hydrogenation reaction was performed at a hydrogen pressure of 10 MPa and a temperature of 180 ° C. for 4 hours. The solution was taken out of the autoclave and subjected to pressure filtration using a membrane filter having a pore size of 0.1 μm, whereby a colorless and transparent solution was obtained.

The solution was added as a stabilizer to Sumilizer GS.
Was added to the polymer in an amount of 0.3% by weight, followed by concentration under reduced pressure and flashing, and the solvent was distilled off to obtain a massive colorless transparent hydrogenated styrene-p-methylstyrene copolymer.
^The degree of hydrogenation determined from ¹ H-NMR was 100%. The number average molecular weight was 120,000, and the molecular weight distribution was 1.40. Further, the glass transition temperature measured by DSC was 146 ° C., and the heat distortion temperature of the molded product was 113 ° C., and it was not possible to increase the heat distortion temperature by introducing a unit derived from p-methylstyrene.

Comparative Example 6 A copolymer obtained by the same method as in Comparative Example 1 was prepared at a cylinder temperature of 320.degree.
It was formed into a 6 mm disk. 100 ℃
And the groove depth of the disk was measured to be 94% of the groove depth before heating.

Comparative Example 7 A copolymer obtained by the same method as in Comparative Example 2 was prepared at a cylinder temperature of 320.degree.
It was formed into a 6 mm disk. 100 ℃
And the groove depth of the disk was measured to be 86% of the groove depth before heating.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuki Kono 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Pref. AB04P AR16R AR17R AR18R AS01R AS02R AS03R AS04R CA04 CA05 CA31 DA04 DA22 HA04 HB02 HB16 HB17 HD22 HE41 JA32 JA36

Claims (9)

[Claims] 1. The following formulas (1) to (5) obtained by polymerizing a styrene monomer, an α-substituted styrene monomer and, if necessary, a conjugated diene monomer: 42 ≦ x ≦ 95 (1) 3 ≦ y ≦ 40 (2) 0 ≦ z ≦ 30 (3) x + y + z = 100 (4) 0.05 ≦ y / (x + y) ≦ 0. 40 (5) (where x is the weight% of the unit derived from the styrene monomer, y
Is a weight% of a unit derived from an α-substituted styrene monomer, and z is a weight% of a unit derived from a conjugated diene monomer). A styrene-based copolymer having substantially no long-chain chain derived from a unit is subjected to a hydrogenation reaction in the presence of a hydrogenation catalyst, and the aromatic ring and carbon-carbon double-chain included in the styrene-based copolymer are subjected to a hydrogenation reaction. A hydrogenated styrene copolymer obtained by hydrogenating a bond. 2. The hydrogenated styrene-based copolymer according to claim 1, wherein the units derived from the conjugated diene monomer contained in the styrene-based copolymer form a block type structure. 3. The method according to claim 1, wherein the molecular weight distribution is 4.0 or less.
Or the hydrogenated styrenic copolymer according to 2. 4. The hydrogenated styrene copolymer according to claim 1, which has a heat distortion temperature of 100 to 180 ° C. 5. The hydrogenated styrenic copolymer contains a metal, and its content is 10 ppm or less.
The hydrogenated styrene copolymer according to any one of the above. 6. A styrene monomer, an α-substituted styrene monomer and, if necessary, a conjugated diene monomer at a temperature of 4 ° C.
The method for producing a hydrogenated styrene-based copolymer according to any one of claims 1 to 5, wherein the styrene-based copolymer is obtained by polymerizing at 0 to 70 ° C. 7. When hydrogenating an aromatic ring and a carbon-carbon double bond contained in the styrenic copolymer, the temperature is set to 70.
The method for producing a hydrogenated styrene-based copolymer according to claim 6, wherein the temperature is kept in a range of from -220C. 8. An optical material mainly comprising the hydrogenated styrene copolymer according to any one of claims 1 to 5. 9. An optical disk substrate mainly comprising the hydrogenated styrene-based copolymer according to any one of claims 1 to 5.