WO2010016376A1

WO2010016376A1 - Optical element and optical pickup device

Info

Publication number: WO2010016376A1
Application number: PCT/JP2009/062964
Authority: WO
Inventors: 大輔渡邉
Original assignee: コニカミノルタオプト株式会社
Priority date: 2008-08-08
Filing date: 2009-07-17
Publication date: 2010-02-11
Also published as: JPWO2010016376A1

Abstract

Provided are an optical element and an optical pickup device which can prevent lowering of the optical performance caused by a fluorination process. The optical element has a molded portion molded by a resin material. The resin material contains a resin having an alicyclic hydrocarbon structure, wherein each unit structure has three or less tertiary carbon atoms. The molded portion has, on the surface thereof, a layer containing a resin having the alicyclic hydrocarbon structure in which at least one hydrogen atom is replaced by a fluorine atom.

Description

Optical element and optical pickup device

The present invention relates to an optical element and an optical pickup device.

Conventionally, a resin material having an alicyclic structure has a low water absorption and is preferably used as a material for an optical element. Further, such an optical element is subjected to antireflection treatment from the viewpoint of increasing the transmittance.

Here, as an antireflection method, an antireflection effect is obtained by attaching a vapor deposition film of an inorganic material or by fluorinating the fluorine gas by substituting CH bonds in the resin with CF bonds. A method (for example, refer to Patent Document 1) is known.

Of these, the method of applying a vapor deposition film made of an inorganic material requires a large-scale apparatus, and the film thickness tends to be non-uniform when the surface angle becomes tight. In addition, the adhesion between the inorganic layer (deposited film) and the resin layer (base material) is poor, and film peeling occurs when short-wavelength light such as blue laser is irradiated.

On the other hand, since the method of performing the fluorination treatment is performed in the gas phase, it is preferable because a uniform film can be formed regardless of the surface angle.

However, when the fluorination treatment is applied to the objective lens of the optical pickup device having a high NA and the imaging system lens having a high pixel count, optical performance such as aberration and MTF is deteriorated.

JP 2005-274748 A

An object of the present invention is to provide an optical element and an optical pickup device that can prevent a decrease in optical performance due to a fluorination treatment.

According to one aspect of the present invention, the optical element of the present invention is an optical element having a molded part molded from a resin material,
The resin material is
A resin having an alicyclic hydrocarbon structure, wherein the number of tertiary carbons in the unit structure is 3 or less,
The molded part has a layer containing a resin in which at least a part of hydrogen constituting the alicyclic hydrocarbon structure is substituted with fluorine on the surface.

In the optical element of the present invention,
The thickness of the fluorinated film is preferably 50 to 300 nm.

In the optical element of the present invention,
The density of the resin material is preferably less than 1 g / cm ³ .

In the optical element of the present invention,
It is preferable that an antireflection coating made of an inorganic material is provided on the fluorinated film.

In the optical element of the present invention,
The numerical aperture NA on the image side is 0.8 or more,
An objective lens of the optical pickup device is preferable.

According to another aspect of the present invention, in the optical pickup device,
The optical element of the present invention is provided as an objective lens.

The present inventors have conducted intensive research on the deterioration of optical performance due to the fluorination treatment, and transmitted light of each wavelength of 405 nm, 650 nm, and 780 nm to an objective lens for an optical pickup device used at a single wavelength. As a result, it was found that no aberration occurred at 650 nm and 780 nm, and aberration occurred only at 405 nm. From this, it was considered that when the reflection was prevented by the fluorination treatment, the light beam path varied with respect to light having a short wavelength. In addition, when the cross section of the fluorinated lens was observed, it was observed that the interface between the resin portion layer not subjected to fluorination treatment and the resin portion layer subjected to fluorination treatment was wavy. As a result of investigations, it was found that the interface wavy due to local progress in fluorination. From this, it was considered that the optical performance was deteriorated as a result of bending the short-wavelength light by the undulation of the interface.

In order to prevent such undulation of the interface, it is considered effective to make the reactivity of the resin part with respect to fluorine uniform at the molecular level, and the C—H bond is converted into a C—F bond by radical reaction. Focusing on the fluorination mechanism of substitution, we came to the conclusion that it is better to have as few unstable tertiary carbons as possible in the resin, and if the number of tertiary carbons per unit structure is 3 or less It has been found that a decrease in optical performance is prevented.

That is, according to the present invention, the surface of the molded part is fluorinated to form a fluorinated film, that is, contains a resin in which at least a part of hydrogen constituting the alicyclic hydrocarbon structure is substituted with fluorine. The resin material of the molding part has an alicyclic hydrocarbon structure and contains a resin having a tertiary carbon number of 3 or less in the unit structure. The interface between the partial layer and the fluorinated resin portion layer can be flattened, and as a result, a decrease in optical performance due to the fluorination treatment can be prevented.

It is drawing which shows schematic structure of the optical pick-up apparatus used by preferable embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[1] Optical pickup device 30
As shown in FIG. 1, the optical pickup device 30 includes a semiconductor laser oscillator 32 as a light source. The semiconductor laser oscillator 32 emits blue light (blue-violet light) having a specific wavelength (for example, 405 nm) having a wavelength of 380 to 420 nm for BD (Blu-ray Disc). On the optical axis of the blue-violet light emitted from the semiconductor laser oscillator 32, a collimator 33, a beam splitter 34, a ¼ wavelength plate 35, an aperture 36, and an objective lens 37 are arranged in a direction away from the semiconductor laser oscillator 32. Are sequentially arranged.

A sensor lens group 38 and a sensor 39 each including two sets of lenses are sequentially arranged at a position close to the beam splitter 34 and in a direction orthogonal to the optical axis of the blue-violet light described above.
[1-2] Objective lens 37
The objective lens 37 is disposed at a position facing a high-density optical disc D (BD (Blu-ray Disc) optical disc), and collects blue-violet light emitted from the semiconductor laser oscillator 32 on one surface of the optical disc D. It comes to shine. The objective lens 37 has an image-side numerical aperture NA of 0.8 or more. The objective lens 37 is provided with a two-dimensional actuator 40, and the objective lens 37 is movable on the optical axis by the operation of the two-dimensional actuator 40.

As shown in the enlarged view of FIG. 1, the objective lens 37 is mainly composed of a molding part 50, and a fluorinated film 55 and an antireflection film 60 are formed on the surface 37a.
[1-2.1] Molding unit 50
Among these, the shaping | molding part 50 is shape | molded by the lens shape, and exhibits essential optical functions, such as a condensing function. The molded part 50 is molded from a resin material. The resin material has an alicyclic hydrocarbon structure, and contains a resin having three or less tertiary carbons in the unit structure as a base resin. Preferably, the density is less than 1 g / cm ³ .

Here, the unit structure in the present invention refers to a unit structure in a monomer. If the resin is a copolymer, it refers to a unit structure in a monomer having the largest number of tertiary carbons.
[1-2.1A] Resin Material of Molded Part 50 The alicyclic hydrocarbon resin having 3 or less tertiary carbons used in the present invention is not particularly limited, but the following resins are preferably used.

As the polymer having an alicyclic structure, the repeating unit (a) having an alicyclic structure represented by the following formula (1), the following formula (2) and / or the following in all polymer repeating units: The repeating unit (b) having a chain structure represented by the formula (3) is contained so that the total content is 90% by mass or more, and the content of the repeating unit (b) is 1% by mass or more and 10%. An alicyclic hydrocarbon copolymer that is less than mass% is preferred.

In the formula (1), X is an alicyclic hydrocarbon group, and in the formulas (1), (2), and (3), R1 to R13 are each independently a hydrogen atom or a chain hydrocarbon group. , Halogen atom, alkoxy group, hydroxy group, ether group, ester group, cyano group, amide group, imide group, silyl group, and polar group (halogen atom, alkoxy group, hydroxy group, ether group, ester group, cyano group, A chain hydrocarbon group substituted with an amide group, an imide group, or a silyl group, and among them, a hydrogen atom or a chain hydrocarbon group having 1 to 6 carbon atoms is preferred for heat resistance and low water absorption. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and examples of the chain hydrocarbon group substituted with a polar group include 1 to 20 carbon atoms, preferably Is And a halogenated alkyl group having 1 to 6, more preferably 1 to 6. Examples of the chain hydrocarbon group include an alkyl group having 1 to 20, preferably 1 to 10, and more preferably 1 to 6 carbon atoms; Examples thereof include alkenyl groups having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms.

X in the general formula (1) represents an alicyclic hydrocarbon group, and the number of carbon atoms constituting the group is usually 4 to 20, preferably 4 to 10, more preferably 5 to 7. is there. Birefringence can be reduced by setting the number of carbon atoms constituting the alicyclic structure within this range.

The alicyclic hydrocarbon group may have a carbon-carbon unsaturated bond, but the content thereof is 10% or less, preferably 5% or less, more preferably 3% or less of the total carbon-carbon bonds. is there. By setting the carbon-carbon unsaturated bond of the alicyclic hydrocarbon group within this range, transparency and heat resistance are improved. The carbon constituting the alicyclic hydrocarbon group includes a hydrogen atom, a hydrocarbon group, a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group, a silyl group, and A chain hydrocarbon group or the like substituted with a polar group (halogen atom, alkoxy group, hydroxy group, ether group, ester group, cyano group, amide group, imide group, or silyl group) may be bonded. A hydrogen atom or a chain hydrocarbon group having 1 to 6 carbon atoms is preferred in terms of heat resistance and low water absorption.

In the formula (3),... Represents a carbon-carbon saturated or carbon-carbon unsaturated bond in the main chain. When transparency and heat resistance are strongly required, the content of unsaturated bonds. Is usually not more than 10%, preferably not more than 5%, more preferably not more than 3% of the total carbon-carbon bonds constituting the main chain.

Among the repeating units represented by the formula (1), the repeating unit represented by the following formula (4) is excellent in terms of heat resistance and low water absorption.

Among the repeating units represented by the formula (2), the repeating unit represented by the following formula (5) is excellent in terms of heat resistance and low water absorption.

Among the repeating units represented by the formula (3), the repeating unit represented by the following formula (6) is excellent in terms of heat resistance and low water absorption.

In formula (4), formula (5), and formula (6), Ra, Rb, Rc, Rd, Re, Rf, Rg, Rh, Ri, Rj, Rk, Rl, Rm, and Rn are each independently hydrogen. An atom or a lower chain hydrocarbon group, a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms is excellent in terms of heat resistance and low water absorption.

Among the repeating units having a chain structure represented by the formulas (2) and (3), the repeating unit having a chain structure represented by the formula (3) is stronger in the obtained hydrocarbon polymer. Excellent characteristics.

In the present invention, a repeating unit (a) having an alicyclic structure represented by the formula (1) and a chain represented by the formula (2) and / or the formula (3) in the hydrocarbon copolymer. The total content with the repeating unit (b) in the shape structure is usually 90% or more, preferably 95% or more, more preferably 97% or more, on a mass basis. By setting the total content within the above range, low birefringence, heat resistance, low water absorption, and mechanical strength are highly balanced.

The content of the repeating unit (b) having a chain structure in the alicyclic hydrocarbon copolymer is appropriately selected according to the purpose of use, but is usually 1% or more and less than 10%, preferably 1% on a mass basis. It is 8% or less, more preferably 2% or more and 6% or less. When the content of the repeating unit (b) is in the above range, low birefringence, heat resistance, and low water absorption are highly balanced.

Further, the chain length of the repeating unit (a) is sufficiently shorter than the molecular chain length of the alicyclic hydrocarbon copolymer, and specifically, A = (repeating unit having an alicyclic structure (a ) Chain weight average molecular weight), B = (weight average molecular weight of alicyclic hydrocarbon copolymer (Mw) × (number of repeating unit (a) having alicyclic structure / alicyclic hydrocarbon system) A) is 30% or less of B, preferably 20% or less, more preferably 15% or less, and particularly preferably 10% or less. When A is outside this range, the low birefringence is poor.

Furthermore, it is preferable that the chain length of the repeating unit (a) has a specific distribution. Specifically, A = (weight average molecular weight of the chain of the repeating unit (a) having an alicyclic structure), C = (number average molecular weight of the chain of the repeating unit (a) having an alicyclic structure). In some cases, A / C is preferably in the range of 1.3 or more, more preferably 1.3 to 8, and most preferably 1.7 to 6. If A / C is excessively small, the degree of block increases, and if it is excessively large, the degree of randomness increases, and in any case, low birefringence is inferior.

The molecular weight of the alicyclic hydrocarbon copolymer of the present invention is 1,000 in terms of polystyrene (or polyisoprene) converted weight average molecular weight (Mw) measured by gel permeation chromatography (hereinafter, GPC). It is in the range of ˜1,000,000, preferably 5,000 to 500,000, more preferably 10,000 to 300,000, and most preferably 50,000 to 250,000. If the weight average molecular weight (Mw) of the alicyclic hydrocarbon copolymer is excessively small, the strength characteristics of the molded product are inferior. Conversely, if the molecular weight is excessively large, the birefringence of the molded product increases.

The molecular weight distribution of such a copolymer can be appropriately selected according to the purpose of use, but the ratio (Mw) of polystyrene (or polyisoprene) -converted weight average molecular weight (Mw) and number average molecular weight (Mn) measured by GPC. / Mn), usually 2.5 or less, preferably 2.3 or less, more preferably 2 or less. When Mw / Mn is in this range, mechanical strength and heat resistance are highly balanced.

The glass transition temperature (Tg) of the copolymer may be appropriately selected according to the purpose of use, but is usually 50 ° C to 250 ° C, preferably 70 ° C to 200 ° C, more preferably 90 ° C to 180 ° C. .
(Method for producing alicyclic hydrocarbon-based copolymer)
The production method of the alicyclic hydrocarbon copolymer of the present invention includes: (1) copolymerizing an aromatic vinyl compound and another monomer copolymerizable with the main chain and aromatic ring carbon-carbon ring. Examples thereof include a method of hydrogenating a saturated bond, and (2) a method of copolymerizing an alicyclic vinyl compound with another monomer copolymerizable and hydrogenating if necessary.

When the alicyclic hydrocarbon-based copolymer of the present invention is produced by the above-described method, the aromatic vinyl compound and / or other monomer copolymerizable with the alicyclic vinyl compound (a ′) ( b ′), the repeating unit derived from the compound (a ′) in the copolymer is D = (weight of the repeating unit chain derived from the aromatic vinyl compound and / or the alicyclic vinyl compound) Average molecular weight), E = (Weight average molecular weight of hydrocarbon copolymer (Mw) × (Number of repeating units derived from aromatic vinyl compound and / or alicyclic vinyl compound / Hydrocarbon copolymer) Of the copolymer having a chain structure in which D is 30% or less of E, preferably 20% or less, more preferably 15% or less, and most preferably 10% or less. Main chain, aromatic ring and cycloalkene It can be efficiently obtained by a method for hydrogenating carbon-carbon unsaturated bond - unsaturated carbon ring and the like. When D is out of the above range, the low birefringence of the resulting alicyclic hydrocarbon copolymer is poor.

In the present invention, the method (1) is preferable because an alicyclic hydrocarbon copolymer can be obtained more efficiently.

The copolymer before hydrogenation further has a D / F when F = (number average molecular weight of a chain of repeating units derived from an aromatic vinyl compound and / or an alicyclic vinyl compound). A certain range is preferable. Specifically, D / F is preferably 1.3 or more, more preferably 1.3 or more and 8 or less, and most preferably 1.7 or more and 6 or less. When D / F is outside this range, the low birefringence of the resulting alicyclic hydrocarbon copolymer is poor.

The weight average molecular weight and number average molecular weight of the chain of repeating units derived from the above compound (a ′) are, for example, unsaturated dicarboxylic acids in the main chain of the aromatic vinyl copolymer described in the document Macromolecules 1983, 16, 1925-1928. It can be confirmed by, for example, a method of measuring the molecular weight of the aromatic vinyl chain taken out by reductive decomposition after adding a heavy bond with ozone.

The molecular weight of the copolymer before hydrogenation is 1,000 to 1,000,000, preferably 5,000 to 500,000 in terms of polystyrene (or polyisoprene) equivalent weight average molecular weight (Mw) measured by GPC. More preferably, it is in the range of 10,000 to 300,000. When the weight average molecular weight (Mw) of the copolymer is excessively small, the strength characteristics of the molded product of the alicyclic hydrocarbon copolymer obtained therefrom are inferior. Conversely, when the copolymer is excessively large, the hydrogenation reactivity is inferior.

Specific examples of the aromatic vinyl compound used in the method (1) include, for example, styrene, α-methylstyrene, α-ethylstyrene, α-propylstyrene, α-isopropylstyrene, α-t-butylstyrene. , 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-t-butylstyrene, monochlorostyrene, monofluorostyrene, 4-phenylstyrene, etc., styrene, 2-methylstyrene, 3-methylstyrene 4-methylstyrene and the like are preferable.

Specific examples of the alicyclic vinyl compound used in the method (2) include, for example, cyclobutylethylene, cyclopentylethylene, cyclohexylethylene, cycloheptylethylene, cyclooctylethylene, α-methylcyclohexylethylene, α-t. -Butylcyclohexylethylene, cyclopentenylethylene, cyclohexenylethylene, cycloheptenylethylene, cyclooctenylethylene, cyclodecenylethylene, α-methylcyclohexenylethylene, α-t-butylcyclohexenylethylene, and the like. Of these, cyclohexylethylene and α-methylcyclohexylethylene are preferred.

These aromatic vinyl compounds and alicyclic vinyl compounds can be used alone or in combination of two or more.

Other monomers that can be copolymerized are not particularly limited, but chain vinyl compounds and chain conjugated diene compounds are used. When chain conjugated dienes are used, the operability in the production process is excellent. The resulting alicyclic hydrocarbon copolymer is excellent in strength properties.

Specific examples of the chain vinyl compound include chain olefin monomers such as ethylene, propylene, 1-butene, 1-pentene and 4-methyl-1-pentene; 1-cyanoethylene (acrylonitrile), 1-cyano- Nitrile monomers such as 1-methylethylene (methacrylonitrile) and 1-cyano-1-chloroethylene (α-chloroacrylonitrile); 1- (methoxycarbonyl) -1-methylethylene (methacrylic acid methyl ester), 1- (Ethoxycarbonyl) -1-methylethylene (methacrylic acid ethyl ester), 1- (propoxycarbonyl) -1-methylethylene (methacrylic acid propyl ester), 1- (butoxycarbonyl) -1-methylethylene (methacrylic) Acid butyl ester), 1-methoxycarbo (Meth) acrylic acid such as ruethylene (acrylic acid methyl ester), 1-ethoxycarbonylethylene (acrylic acid ethyl ester), 1-propoxycarbonylethylene (acrylic acid propyl ester), 1-butoxycarbonylethylene (acrylic acid butyl ester) Examples include ester monomers, unsaturated fatty acid monomers such as 1-carboxyethylene (acrylic acid), 1-carboxy-1-methylethylene (methacrylic acid), and maleic anhydride, among which chain olefin monomers are preferred, Most preferred are ethylene, propylene and 1-butene.

Examples of the chain conjugated diene include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like. Of these chain vinyl compounds and chain conjugated dienes, chain conjugated dienes are preferable, and butadiene and isoprene are particularly preferable. These chain vinyl compounds and chain conjugated dienes can be used alone or in combination of two or more.

These chain vinyl compounds can be used alone or in combination of two or more.

The method for polymerizing the compound (a ′) is not particularly limited, but after the polymerization is started using a batch polymerization method (batch method), a monomer sequential addition method (a part of the total amount of monomers used), And a method of proceeding polymerization by successively adding monomers). In particular, when the monomer sequential addition method is used, a hydrocarbon copolymer having a preferable chain structure can be obtained. The copolymer before hydrogenation has a more random chain structure, so that the above-mentioned D value is smaller and / or the D / F shows a larger value. The degree of randomness of the copolymer is determined by the speed ratio between the polymerization rate of the aromatic vinyl compound and the polymerization rate of other copolymerizable monomers, and the smaller this speed ratio, the more It has a random chain structure.

According to the monomer sequential addition method, since the uniformly mixed monomer is sequentially added into the polymerization system, unlike the batch method, the polymerization selectivity of the monomer is further lowered during the growth process by polymer polymerization. The resulting copolymer has a more random chain structure. In addition, since the accumulation of polymerization reaction heat in the polymerization system is small, the polymerization temperature can be kept low and stable.

In the case of the monomer sequential addition method, first, out of the total amount of monomers used, usually 0.01% to 60% by mass, preferably 0.02% to 20% by mass, more preferably 0.05% to 10% by mass. Polymerization is started by adding an initiator in the state in which the monomer is present in the polymerization reactor as an initial monomer. When the initial monomer amount is in such a range, the reaction heat generated in the initial reaction after the initiation of polymerization can be easily removed, and the resulting copolymer can have a more random chain structure.

When the reaction is continued until the polymerization conversion rate of the initial monomer is 70% or more, preferably 80% or more, more preferably 90% or more, the chain structure of the resulting copolymer becomes more random. Thereafter, the remainder of the monomer is continuously added, and the rate of addition is determined in consideration of the consumption rate of the monomer in the polymerization system.

Usually, when the time required for the polymerization addition rate of the initial monomer to reach 90% is T, and the ratio (%) of the initial monomer to all the monomers used is I, the relational expression [(100−I) × T / I ] Is determined so that the addition of the remaining monomer is completed within a range of 0.5 to 3 times, preferably 0.8 to 2 times, more preferably 1 to 1.5 times the time given by Specifically, the initial monomer amount and the rate of addition of the remaining monomers are determined so that they are usually in the range of 0.1 to 30 hours, preferably 0.5 to 5 hours, more preferably 1 to 3 hours. Further, the total monomer polymerization conversion immediately after completion of the monomer addition is usually 80% or more, preferably 85% or more, and more preferably 90% or more. When the total monomer polymerization conversion rate immediately after the completion of monomer addition is within the above range, the chain structure of the resulting copolymer becomes more random.

The polymerization reaction is not particularly limited, such as radical polymerization, anionic polymerization, and cationic polymerization. However, the polymerization operation, the ease of the hydrogenation reaction in the post-process, and the mechanical properties of the finally obtained hydrocarbon copolymer are not limited. In view of strength, the anionic polymerization method is preferable.

In the case of radical polymerization, methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used in the presence of an initiator, usually at 0 ° C. to 200 ° C., preferably 20 ° C. to 150 ° C. In particular, bulk polymerization and suspension polymerization are desirable when it is necessary to prevent impurities from being mixed into the resin. Radical initiators include organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl-peroxy-2-ethylhexanoate, azoisobutyronitrile, 4,4-azobis-4-cyanopentanoic acid An azo compound such as azodibenzoyl, a water-soluble catalyst typified by potassium persulfate and ammonium persulfate, a redox initiator, and the like can be used.

In the case of anionic polymerization, bulk polymerization, solution polymerization, slurry polymerization, etc. in the temperature range of usually 0 ° C. to 200 ° C., preferably 20 ° C. to 100 ° C., particularly preferably 20 ° C. to 80 ° C. in the presence of an initiator. However, solution polymerization is preferable in view of removal of reaction heat. In this case, an inert solvent capable of dissolving the polymer and its hydride is used. Examples of the inert solvent used in the solution reaction include aliphatic hydrocarbons such as n-butane, n-pentane, iso-pentane, n-hexane, n-heptane, and iso-octane; cyclopentane, cyclohexane, methylcyclopentane, Examples include alicyclic hydrocarbons such as methylcyclohexane and decalin; aromatic hydrocarbons such as benzene and toluene. Among them, when aliphatic hydrocarbons and alicyclic hydrocarbons are used, hydrogenation reaction is also performed. It can be used as it is as an inert solvent. These solvents can be used alone or in combination of two or more, and are usually used at a ratio of 200 to 10,000 parts by mass with respect to 100 parts by mass of all the monomers used.

Examples of the initiator for anionic polymerization include monoorganolithium such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, and phenyllithium, dilithiomethane, 1,4-diobtan, 1,4-dilithiol. A polyfunctional organolithium compound such as 2-ethylcyclohexane can be used.

In the polymerization reaction, a polymerization accelerator, a randomizer (an additive having a function of preventing a chain of a certain component from becoming long), or the like can be used. In the case of anionic polymerization, for example, a Lewis base compound can be used as a randomizer. Specific examples of the Lewis base compound include ether compounds such as dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, diphenyl ether, ethylene glycol diethyl ether, ethylene glycol methyl phenyl ether; tetramethylethylenediamine, trimethylamine, triethylamine, pyridine A tertiary amine compound such as potassium-t-amyl oxide and potassium-t-butyl oxide; and a phosphine compound such as triphenylphosphine. These Lewis base compounds can be used alone or in combination of two or more.

The polymer obtained by the above radical polymerization or anion polymerization can be recovered by a known method such as a steam stripping method, a direct solvent removal method, or an alcohol coagulation method. In addition, when an inert solvent is used in the hydrogenation reaction during the polymerization, the polymer is not recovered from the polymerization solution and can be used as it is in the hydrogenation step.
(Method of hydrogenating unsaturated bonds)
When carrying out hydrogenation reactions such as carbon-carbon double bonds of unsaturated rings such as aromatic rings and cycloalkene rings of the copolymer before hydrogenation, and unsaturated bonds of the main chain, the reaction method and reaction form are special. There is no particular limitation, and it may be carried out according to a known method, but a hydrogenation method that can increase the hydrogenation rate and has little polymer chain scission reaction that occurs simultaneously with the hydrogenation reaction is preferable, for example, in an organic solvent, nickel, The method is performed using a catalyst containing at least one metal selected from cobalt, iron, titanium, rhodium, palladium, platinum, ruthenium, and rhenium. As the hydrogenation catalyst, either a heterogeneous catalyst or a homogeneous catalyst can be used.

The heterogeneous catalyst can be used in the form of a metal or a metal compound or supported on a suitable carrier. Examples of the carrier include activated carbon, silica, alumina, calcium carbide, titania, magnesia, zirconia, diatomaceous earth, silicon carbide and the like. The amount of the catalyst supported is usually 0.01 to 80% by mass, preferably 0.8. The range is from 05 to 60% by mass. The homogeneous catalyst is a catalyst in which a nickel, cobalt, titanium or iron compound and an organometallic compound (for example, an organoaluminum compound or an organolithium compound) are combined, or an organometallic complex catalyst such as rhodium, palladium, platinum, ruthenium or rhenium. Can be used. Examples of the nickel, cobalt, titanium, or iron compound include acetylacetone salts, naphthene salts, cyclopentadienyl compounds, cyclopentadienyl dichloro compounds, and the like of various metals. As the organic aluminum compound, alkylaluminum such as triethylaluminum and triisobutylaluminum, aluminum halide such as diethylaluminum chloride and ethylaluminum dichloride, alkylaluminum hydride such as diisobutylaluminum hydride and the like are preferably used.

Examples of organometallic complex catalysts include metal complexes such as γ-dichloro-π-benzene complex, dichloro-tris (triphenylphosphine) complex, hydrido-chloro-triphenylphosphine) complex of the above metals. These hydrogenation catalysts can be used alone or in combination of two or more, and the amount used is usually 0.01 to 100 parts, preferably on a mass basis with respect to the polymer. 0.05 to 50 parts, more preferably 0.1 to 30 parts.

The hydrogenation reaction is usually from 10 ° C. to 250 ° C., but preferably from 50 ° C. to 200 ° C. because the hydrogenation rate can be increased and the polymer chain scission reaction that occurs simultaneously with the hydrogenation reaction can be reduced. More preferably, it is 80 ° C to 180 ° C. The hydrogen pressure is usually 0.1 MPa to 30 MPa, but in addition to the above reasons, it is preferably 1 MPa to 20 MPa, more preferably 2 MPa to 10 MPa from the viewpoint of operability.

The hydrogenation rate of the hydride obtained in this way is determined by 1H-NMR, as determined by carbon-carbon unsaturated bond of the main chain, carbon-carbon double bond of aromatic ring, carbon-carbon of unsaturated ring. All of the double bonds are usually 90% or more, preferably 95% or more, more preferably 97% or more. When the hydrogenation rate is low, the low birefringence, thermal stability, etc. of the resulting copolymer are lowered.

The method for recovering the hydride after completion of the hydrogenation reaction is not particularly limited. Usually, after removing the hydrogenation catalyst residue by a method such as filtration or centrifugation, the solvent is removed directly from the hydride solution by drying, the hydride solution is poured into a poor solvent for the hydride, and the hydride A method of coagulating can be used.

As the polymer having an alicyclic structure, a block copolymer having a polymer block [A] and a polymer block [B] is more preferable. The polymer block [A] contains a repeating unit [1] represented by the following formula (1). The content of the repeating unit [1] in the polymer block [A] is preferably 50 mol% or more, more preferably 70 mol% or more, and particularly preferably 90 mol% or more.

(Wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ^{2 to} R ¹² each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a hydroxyl group, a carbon number of 1 R ^{2 to} R ¹² are R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ^{12. The same} applies hereinafter.)
A preferred structure of the repeating unit [1] represented by the above formula (1) is such that R ¹ is hydrogen or a methyl group, and R ² -R ¹² are all hydrogen. When the content of the repeating unit [1] in the polymer block [A] is in the above range, transparency and mechanical strength are excellent. The remainder other than the repeating unit [1] in the polymer block [A] is a hydrogenated repeating unit derived from a chain conjugated diene or a chain vinyl compound.

The polymer block [B] contains the repeating unit [1] and the repeating unit [2] represented by the following formula (2) and / or the repeating unit [3] represented by the following formula (3). The content of the repeating unit [1] in the polymer block [B] is preferably 40 to 95 mol%, more preferably 50 to 90 mol%. When the content of the repeating unit [1] is in the above range, transparency and mechanical strength are excellent. When the molar fraction of the repeating unit [2] in the block [B] is m2 (mol%) and the molar fraction of the repeating unit [3] is m3 (mol%), 2 × m2 + m3 is preferably It is 2 mol% or more, more preferably 5 to 60 mol%, most preferably 10 to 50 mol%.

(In the formula, R ¹³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.)
A preferred structure of the repeating unit [2] represented by the above formula (2) is that in which R ¹³ is hydrogen or a methyl group.

(In the formula, each of R ¹⁴ and R ¹⁵ independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.)
A preferred structure of the repeating unit [3] represented by the above formula (3) is one in which R ¹⁴ is hydrogen and R ¹⁵ is a methyl group or an ethyl group.

If the content of the repeating unit [2] or the repeating unit [3] in the polymer block [B] is too small, the mechanical strength is lowered. Therefore, when the content of the repeating unit [2] and the repeating unit [3] is in the above range, transparency and mechanical strength are excellent. The polymer block [B] may further contain a repeating unit [X] represented by the following formula (X). The content of the repeating unit [X] is an amount that does not impair the properties of the block copolymer of the present invention, and is preferably 30 mol% or less, more preferably 20 mol% or less, based on the entire block copolymer. It is.

(Wherein R ²⁵ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, R ²⁶ represents a nitrile group, an alkoxycarbonyl group, a formyl group, a hydroxycarbonyl group, or a halogen group, and R ²⁷ represents a hydrogen atom. Or R ²⁶ and R ²⁷ may be bonded to each other to form an acid anhydride group or an imide group.)
In addition, the block copolymer used in the present invention has a molar fraction of the repeating unit [1] in the polymer block [A] and a molar fraction of the repeating unit [1] in the polymer block [B]. In the case of b, it is preferable that a> b. Thereby, it is excellent in transparency and mechanical strength.

Further, the block copolymer used in the present invention has a ratio when the number of moles of all repeating units constituting the block [A] is ma and the number of moles of all repeating units constituting the block [B] is mb. (Ma: mb) is preferably 5:95 to 95: 5, more preferably 30:70 to 95: 5, and particularly preferably 40:60 to 90:10. When (ma: mb) is in the above range, the mechanical strength and heat resistance are excellent.

The molecular weight of the block copolymer used in the present invention is a weight average molecular weight in terms of polystyrene (or polyisoprene) measured by gel permeation chromatography (hereinafter referred to as GPC) using tetrahydrofuran (THF) as a solvent ( (Hereinafter referred to as Mw)) is preferably in the range of 10,000 to 300,000, more preferably 15,000 to 250,000, and particularly preferably 20,000 to 200,000. When the Mw of the block copolymer is in the above range, the balance of mechanical strength, heat resistance, and moldability is excellent.

The molecular weight distribution of the block copolymer can be appropriately selected according to the purpose of use, but the ratio (Mw) of polystyrene (or polyisoprene) converted Mw and number average molecular weight (hereinafter referred to as Mn) measured by GPC. / Mn), preferably 5 or less, more preferably 4 or less, particularly preferably 3 or less. When Mw / Mn is in this range, the mechanical strength and heat resistance are excellent.

The glass transition temperature (hereinafter referred to as Tg) of the block copolymer may be appropriately selected depending on the purpose of use, but is measured on the high temperature side by a differential scanning calorimeter (hereinafter referred to as DSC). The value is preferably 70 ° C. to 200 ° C., more preferably 80 ° C. to 180 ° C., and particularly preferably 90 ° C. to 160 ° C.

The block copolymer used in the present invention has a polymer block [A] and a polymer block [B], and even if it is a ([A]-[B]) type diblock copolymer, Even if the [A]-[B]-[A]) type or ([B]-[A]-[B]) type triblock copolymer is used, the polymer block [A] and the polymer block [A] B] may be a block copolymer in which a total of 4 or more are alternately connected. Moreover, the block copolymer which these blocks couple | bonded with radial type may be sufficient.

The block copolymer used in the present invention can be obtained by the following method. As the method, an aromatic vinyl compound or / and a monomer mixture containing an alicyclic vinyl compound having an unsaturated bond in the ring, and a vinyl monomer (excluding an aromatic vinyl compound and an alicyclic vinyl compound) are used. A block having a polymer block containing a repeating unit derived from an aromatic vinyl compound and / or an alicyclic vinyl compound, and a polymer block containing a repeating unit derived from a vinyl monomer by polymerizing the monomer mixture A copolymer is obtained. And a method of hydrogenating an aromatic ring and / or an aliphatic ring of the block copolymer, a monomer mixture containing a saturated alicyclic vinyl compound, and a vinyl monomer (aromatic vinyl compound and alicyclic vinyl compound) A block copolymer having a polymer block containing a repeating unit derived from an alicyclic vinyl compound, and a polymer block containing a repeating unit derived from a vinyl monomer And the like. Especially, what is more preferable as a block copolymer used for this invention can be obtained with the following method, for example.

(1) As a first method, first, a monomer mixture [a ′] containing 50 mol% or more of an aromatic vinyl compound and / or an alicyclic vinyl compound having an unsaturated bond in the ring is polymerized to obtain an aromatic A polymer block [A ′] containing a repeating unit derived from an aliphatic vinyl compound or / and an alicyclic vinyl compound having an unsaturated bond in the ring is obtained. A monomer mixture containing a vinyl monomer (excluding an aromatic vinyl compound and an alicyclic vinyl compound) in an amount of 2 mol% or more and having an aromatic vinyl compound and / or an unsaturated bond in the ring [ a ′] by polymerizing the monomer mixture [b ′] contained in an amount smaller than the proportion in the aromatic vinyl compound and / or the repeating unit derived from the alicyclic vinyl compound and the repeating derived from the vinyl monomer. A polymer block [B ′] containing units is obtained. After obtaining the block copolymer having the polymer block [A ′] and the polymer block [B ′] through at least these steps, the aromatic ring and / or the aliphatic ring of the block copolymer is hydrogenated. Turn into.

(2) As a second method, first, a polymer containing a repeating unit derived from a saturated alicyclic vinyl compound by polymerizing a monomer mixture [a] containing 50 mol% or more of a saturated alicyclic vinyl compound. A block [A] is obtained. Contains 2 mol% or more of vinyl-based monomers (excluding aromatic vinyl compounds and alicyclic vinyl compounds), and contains saturated alicyclic vinyl compounds in a proportion smaller than the proportion in the monomer mixture [a]. The monomer mixture [b] is polymerized to obtain a polymer block [B] containing a repeating unit derived from a saturated alicyclic vinyl compound and a repeating unit derived from a vinyl monomer. At least through these steps, a block copolymer having the polymer block [A] and the polymer block [B] is obtained.

Among the above methods, the method (1) is more preferable from the viewpoints of availability of monomers, polymerization yield, ease of introduction of the repeating unit [1] into the polymer block [B ′], and the like. .

Specific examples of the aromatic vinyl compound in the method (1) include styrene, α-methyl styrene, α-ethyl styrene, α-propyl styrene, α-isopropyl styrene, α-t-butyl styrene, 2-methyl styrene. 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene, mono Examples thereof include fluorostyrene, 4-phenylstyrene and the like, and those having a substituent such as a hydroxyl group or an alkoxy group. Of these, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene and the like are preferable.

Specific examples of the unsaturated alicyclic vinyl compound in the method (1) include cyclohexenylethylene, α-methylcyclohexenylethylene, α-t-butylcyclohexenylethylene, and the like, and a halogen group and an alkoxy group. Or those having a substituent such as a hydroxyl group.

These aromatic vinyl compounds and alicyclic vinyl compounds can be used alone or in combination of two or more. In the present invention, any one of the monomer mixtures [a ′] and [b ′] In addition, it is preferable to use an aromatic vinyl compound, and it is more preferable to use styrene or α-methylstyrene.

The vinyl monomer used in the above method includes a chain vinyl compound and a chain conjugated diene compound.

Specific examples of the chain vinyl compound include chain olefin monomers such as ethylene, propylene, 1-butene, 1-pentene, and 4-methyl-1-pentene. Among these, chain olefin monomers are preferable, and ethylene Most preferred are propylene and 1-butene.

When polymerizing a monomer mixture containing the above monomers, the polymerization reaction may be carried out by any method such as radical polymerization, anionic polymerization, cationic polymerization, etc., but preferably by anionic polymerization in the presence of an inert solvent. Most preferably, living anionic polymerization is performed.

Anionic polymerization is usually carried out in the presence of a polymerization initiator in a temperature range of 0 ° C. to 200 ° C., preferably 20 ° C. to 100 ° C., particularly preferably 20 ° C. to 80 ° C. Examples of the initiator include monoorganolithium such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium and phenyllithium, dilithiomethane, 1,4-diobtan, 1,4-dilithio-2-ethylcyclohexane. A polyfunctional organolithium compound such as can be used.

Examples of the inert solvent used include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane, and isooctane; cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, decalin And alicyclic hydrocarbons such as benzene, toluene and the like, and the use of aliphatic hydrocarbons and alicyclic hydrocarbons is an inert solvent for hydrogenation reaction. Can be used as is. These solvents can be used alone or in combination of two or more, and are usually used at a ratio of 200 to 10,000 parts by mass with respect to 100 parts by mass of all the monomers used.

When polymerizing each polymer block, a polymerization accelerator, a randomizer, or the like can be used in order to prevent a chain of a certain component from becoming long in each block. In particular, when the polymerization reaction is performed by anionic polymerization, a Lewis base compound or the like can be used as a randomizer. Specific examples of Lewis base compounds include ether compounds such as dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, diphenyl ether, ethylene glycol diethyl ether, ethylene glycol methyl phenyl ether; tetramethylethylenediamine, trimethylamine, triethylamine, pyridine, etc. Tertiary amine compounds; alkali metal alkoxide compounds such as potassium-t-amyl oxide and potassium-t-butyl oxide; and phosphine compounds such as triphenylphosphine. These Lewis base compounds can be used alone or in combination of two or more.

Examples of the method for obtaining a block copolymer by living anionic polymerization include conventionally known sequential addition polymerization reaction method and coupling method. In the present invention, it is preferable to use sequential addition polymerization reaction method.

When the block copolymer having the polymer block [A ′] and the polymer block [B ′] is obtained by the sequential addition polymerization reaction method, a step of obtaining the polymer block [A ′], and a polymer block The process of obtaining [B ′] is performed sequentially and continuously. Specifically, in the presence of the living anion polymerization catalyst in an inert solvent, the monomer mixture [a ′] is polymerized to obtain a polymer block [A ′], and then the monomer mixture [b ′] is added to the reaction system. To continue the polymerization to obtain a polymer block [B ′] connected to the polymer block [A ′]. Furthermore, if desired, the monomer mixture [a ′] is added again for polymerization, the polymer block [A ′] is connected to form a triblock body, and the monomer mixture [b ′] is added again for polymerization. Then, a tetrablock body in which the polymer blocks [B ′] are connected is obtained.

The obtained block copolymer is recovered by a known method such as a steam stripping method, a direct desolvation method, or an alcohol coagulation method. In the polymerization reaction, when an inert solvent is used in the hydrogenation reaction, the polymerization solution can be used as it is in the hydrogenation reaction step, so that the block copolymer need not be recovered from the polymerization solution. .

Of the block copolymer having a polymer block [A ′] and a polymer block [B ′] obtained in the method (1) (hereinafter referred to as a pre-hydrogenation block copolymer), it has the following structure: Those having a repeating unit are preferred.

The polymer block [A ′] constituting the preferred pre-hydrogenation block copolymer is a polymer block containing 50 mol% or more of the repeating unit [4] represented by the following formula (4).

(Wherein R ¹⁶ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ^{17 to} R ²¹ each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a hydroxyl group, a carbon number, 1 is an alkoxy group or a halogen group to 20. Note that the ^[R 17 ^{-R 21]} ^represents an R ^{17, R 18,} · · and ^{R 21.)}
A preferred polymer block [B ′] necessarily contains the repeating unit [4], the repeating unit [5] represented by the following formula (5) and the repeating unit [6] represented by the following formula (6). ] A polymer block containing at least one of the above. Further, when the mole fraction of the repeating unit [4] in the polymer block [A ′] is a ′ and the mole fraction of the repeating unit [4] in the block [B ′] is b ′, a ′> b ′.

(In the formula, R ²² represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.)

(In the formula, R ²³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ²⁴ represents a hydrogen atom, an alkyl group or alkenyl group having 1 to 20 carbon atoms.)
Furthermore, the block [B ′] may contain a repeating unit [Y] represented by the following formula (Y).

(Wherein R ²⁸ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, R ²⁹ represents a nitrile group, an alkoxycarbonyl group, a formyl group, a hydroxycarbonyl group, or a halogen group, and R ³⁰ represents a hydrogen atom. Or R ²⁹ and R ³⁰ may be bonded to each other to form an acid anhydride group or an imide group.)
Furthermore, a preferable block copolymer before hydrogenation is a case where the number of moles of all repeating units constituting the block [A ′] is ma ′ and the number of moles of all repeating units constituting the block [B ′] is mb ′. The ratio (ma ′: mb ′) is 5:95 to 95: 5, more preferably 30:70 to 95: 5, and particularly preferably 40:60 to 90:10. When (ma ′: mb ′) is in the above range, the mechanical strength and heat resistance are excellent.

The molecular weight of the block copolymer before hydrogenation is preferably 12,000 to 400,000, more preferably 19,000 to 350,000, in terms of polystyrene (or polyisoprene) equivalent Mw measured by GPC using THF as a solvent. Particularly preferred is a range of 25,000 to 300,000. When the Mw of the block copolymer is excessively small, the mechanical strength decreases, and when it is excessively large, the hydrogenation rate decreases.

The molecular weight distribution of the block copolymer before hydrogenation can be appropriately selected depending on the purpose of use, but is the ratio (Mw / Mn) of Mw and Mn in terms of polystyrene (or polyisoprene) measured by GPC, It is 5 or less, more preferably 4 or less, and particularly preferably 3 or less. When Mw / Mn is in this range, the hydrogenation rate is improved.

The Tg of the block copolymer before hydrogenation may be appropriately selected according to the purpose of use, but is 70 ° C to 150 ° C, more preferably 80 ° C to 140 ° C, as measured on the high temperature side by DSC. Particularly preferred is 90 ° C to 130 ° C.

Method and reaction for hydrogenating the above-mentioned block copolymer before hydrogenation, such as carbon-carbon unsaturated bonds of unsaturated rings such as aromatic rings and cycloalkene rings, and unsaturated bonds of main chains and side chains There is no particular limitation on the form, and it may be performed according to a known method. However, a hydrogenation method that can increase the hydrogenation rate and has a low polymer chain scission reaction is preferable. For example, in an organic solvent, nickel, cobalt, iron, Examples thereof include a method performed using a catalyst containing at least one metal selected from titanium, rhodium, palladium, platinum, ruthenium, and rhenium. As the hydrogenation catalyst, either a heterogeneous catalyst or a homogeneous catalyst can be used.

The heterogeneous catalyst can be used in the form of a metal or metal compound or supported on a suitable carrier. Examples of the support include activated carbon, silica, alumina, calcium carbide, titania, magnesia, zirconia, diatomaceous earth, silicon carbide and the like, and the supported amount of the catalyst is preferably 0.01 to 80% by mass, more preferably. It is in the range of 0.05 to 60% by mass. The homogeneous catalyst is a catalyst in which a nickel, cobalt, titanium or iron compound and an organometallic compound (for example, an organoaluminum compound or an organolithium compound) are combined, or an organometallic complex catalyst such as rhodium, palladium, platinum, ruthenium or rhenium. Can be used. As the nickel, cobalt, titanium, or iron compound, for example, acetylacetone salt, naphthenic acid salt, cyclopentadienyl compound, cyclopentadienyl dichloro compound and the like of various metals are used. As the organic aluminum compound, alkylaluminum such as triethylaluminum and triisobutylaluminum, aluminum halide such as diethylaluminum chloride and ethylaluminum dichloride, alkylaluminum hydride such as diisobutylaluminum hydride and the like are preferably used.

Examples of organometallic complex catalysts include metal complexes such as γ-dichloro-π-benzene complexes, dichloro-tris (triphenylphosphine) complexes, hydrido-chloro-triphenylphosphine complexes of the above metals. These hydrogenation catalysts can be used alone or in combination of two or more, and the amount used is preferably 0.01 to 100 parts by weight, more preferably 100 parts by weight of the polymer. 0.05 to 50 parts by mass, particularly preferably 0.1 to 30 parts by mass.

The hydrogenation reaction is usually 10 ° C. to 250 ° C., but is preferably 50 ° C. to 200 ° C., more preferably 80 ° C. to 80 ° C., because the hydrogenation rate can be increased and the polymer chain scission reaction can be reduced. 180 ° C. The hydrogen pressure is preferably 0.1 MPa to 30 MPa, but in addition to the above reasons, from the viewpoint of operability, it is more preferably 1 MPa to 20 MPa, and particularly preferably 2 MPa to 10 MPa.

The hydrogenation rate of the block copolymer obtained in this way is determined by 1H-NMR as determined by carbon-carbon unsaturated bonds in the main chain and side chains, and carbon-carbon unsaturation in aromatic rings and cycloalkene rings. Any of the bonds is preferably 90% or more, more preferably 95% or more, and particularly preferably 97% or more. When the hydrogenation rate is low, the low birefringence, thermal stability, etc. of the resulting copolymer are lowered.

After completion of the hydrogenation reaction, the block copolymer is prepared by removing the hydrogenation catalyst from the reaction solution by a method such as filtration or centrifugation, and then removing the solvent directly by drying. It can be recovered by a method such as pouring into a poor solvent and solidifying.
[1-2.1B] Compounding Agents for Resin Materials Various compounding agents can be blended in the polymer of the present invention as necessary. The compounding agent that can be incorporated into the block copolymer is not particularly limited, but stabilizers such as antioxidants, heat stabilizers, light-resistant stabilizers, weather-resistant stabilizers, ultraviolet absorbers, and near-infrared absorbers; Examples thereof include resin modifiers such as lubricants and plasticizers; colorants such as dyes and pigments; antistatic agents, flame retardants, and fillers. These compounding agents can be used alone or in combination of two or more, and the compounding amount is appropriately selected within a range not impairing the effects of the present invention.

In the present invention, among the above-mentioned compounding agents, it is preferable to blend an antioxidant, an ultraviolet absorber, and a light-resistant stabilizer with the polymer. Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. Among them, phenolic antioxidants, particularly alkyl-substituted phenolic antioxidants are preferable. By blending these antioxidants, it is possible to prevent lens coloring and strength reduction due to oxidative deterioration during molding without lowering transparency, heat resistance and the like. These antioxidants can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but the polymer 100 according to the present invention. The amount is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 1 part by mass with respect to parts by mass.

Examples of ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2 -Hydroxy-4-methoxy-2'-benzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2-hydroxy-4-n-octoxybenzophenone, 2,2 ', 4,4'- Benzophenone ultraviolet absorbers such as tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane; 2- (2′-hydroxy-5′-methyl- Phenyl) benzotriazole, 2- (2 -Benzotriazol-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthalimidylmethyl) phenol, 2- (2H-benzotriazol-2-yl) -4-6-bis (1-methyl-1-phenylethyl) phenol, 2- (2′-hydroxy-3 ′, 5′-di-tert-butyl-phenyl) benzotriazole, 2- (2′-hydroxy-3′-second) 3-butyl-5′-methyl-phenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5 ′ -Di-tertiary-amylphenyl) benzotriazole, 2- [2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methyl Benzotriazole UV absorbers such as [phenyl] benzotriazole, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] Etc. Among these, 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4,5,6- Tetrahydrophthalimidylmethyl) phenol, 2- (2H-benzotriazol-2-yl) -4-6-bis (1-methyl-1-phenylethyl) phenol and the like are preferable from the viewpoints of heat resistance and low volatility. .

Examples of the light-resistant stabilizer include benzophenone-based light-resistant stabilizer, benzotriazole-based light-resistant stabilizer, hindered amine-based light-resistant stabilizer, etc., but in the present invention, from the viewpoint of lens transparency, color resistance, etc., hindered amine-based It is preferable to use a light-resistant stabilizer. Among hindered amine light-resistant stabilizers (hereinafter referred to as HALS), those having a polystyrene-equivalent Mn measured by GPC using THF as a solvent are preferably 1000 to 10,000, more preferably 2000 to 5000, Those of 2800 to 3800 are particularly preferred. When Mn is too small, when HALS is blended by heating and kneading into a polymer, a predetermined amount cannot be blended due to volatilization, or foaming or silver streak occurs during heating and melt molding such as injection molding. Sex is reduced. Further, when the lens is used for a long time with the lamp turned on, a volatile component is generated as a gas from the lens. Conversely, if Mn is too large, the dispersibility in the block copolymer is lowered, the transparency of the lens is lowered, and the effect of improving light resistance is reduced. Therefore, in the present invention, a lens having excellent processing stability, low gas generation and transparency can be obtained by setting the HALS Mn within the above range.

Specific examples of such HALS include N, N ′, N ″, N ′ ″-tetrakis- [4,6-bis- {butyl- (N-methyl-2,2,6,6-tetra Methylpiperidin-4-yl) amino} -triazin-2-yl] -4,7-diazadecane-1,10-diamine, dibutylamine and 1,3,5-triazine and N, N′-bis (2,2 , 6,6-Tetramethyl-4-piperidyl) butylamine, poly [{(1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl } {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], 1,6-hexanediamine- N, N'-bis (2,2,6,6-tetramethyl 4-piperidyl) and a polycondensate of morpholine-2,4,6-trichloro-1,3,5-triazine, poly [(6-morpholino-s-triazine-2,4-diyl) (2,2 , 6,6, -tetramethyl-4-piperidyl) imino] -hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]] and other piperidine rings via a triazine skeleton. Bound high molecular weight HALS; polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, 1,2,3,4-butanetetracarboxylic acid and 1,2 , 2,6,6-pentamethyl-4-piperidinol and 3,9-bis (2-hydroxy-1,1-dimethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane Such ester, piperidine ring and the like high molecular weight HALS attached through an ester bond.

Among these, polycondensates of dibutylamine, 1,3,5-triazine and N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1, 1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2 , 2,6,6-tetramethyl-4-piperidyl) imino}], a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and the like. 5,000 to 5,000 are preferred.

The blending amount of the UV absorber and HALS with respect to the block copolymer according to the present invention is preferably 0.01 to 20 parts by mass, more preferably 0.02 to 15 parts by mass, with respect to 100 parts by mass of the polymer. Particularly preferred is 0.05 to 10 parts by mass. If the amount added is too small, the effect of improving light resistance cannot be obtained sufficiently, and coloring occurs when used outdoors for a long time. On the other hand, when the blending amount of HALS is too large, a part of the HALS is generated as a gas, or the dispersibility in the polymer is lowered, and the transparency of the lens is lowered.

In addition, by blending the polymer according to the present invention with a soft polymer having the lowest glass transition temperature of 30 ° C. or less, it is possible to maintain long properties without deteriorating various properties such as transparency, heat resistance, and mechanical strength. It can prevent cloudiness in high temperature and high humidity environment.

Specific examples of the soft polymer include olefin-based soft polymers such as polyethylene, polypropylene, ethylene-α-olefin copolymer, ethylene-propylene-diene copolymer (EPDM); polyisobutylene, isobutylene-isoprene rubber, Isobutylene-based soft polymers such as isobutylene-styrene copolymer; polybutadiene, polyisoprene, butadiene-styrene random copolymer, isoprene-styrene random copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer Butadiene-styrene block copolymer, styrene-butadiene-styrene block copolymer, isoprene-styrene block copolymer, styrene-isoprene-styrene block copolymer, etc. Soft polymers containing silicon; soft polymers containing silicon such as dimethylpolysiloxane and diphenylpolysiloxane; soft acrylic polymers such as polybutyl acrylate, polybutyl methacrylate, and polyhydroxyethyl methacrylate; polyethylene oxide, polypropylene oxide, epichlorohydrin rubber, etc. Epoxy-based soft polymers; fluorine-based soft polymers such as vinylidene fluoride rubber and tetrafluoroethylene-propylene rubber; natural rubber, polypeptide, protein, polyester-based thermoplastic elastomer, vinyl chloride-based thermoplastic elastomer, polyamide And other soft polymers such as thermoplastic elastomers. These soft polymers may have a cross-linked structure or may have a functional group introduced by a modification reaction.

Among the above-mentioned soft polymers, diene-based soft polymers are preferable. Particularly, hydrides obtained by hydrogenating carbon-carbon unsaturated bonds of the soft polymers are advantageous in terms of rubber elasticity, mechanical strength, flexibility, and dispersibility. Excellent. The blending amount of the soft polymer varies depending on the type of the compound, but generally, if the blending amount is too large, the glass transition temperature and the transparency of the polymer are greatly lowered and cannot be used as a lens. On the other hand, if the blending amount is too small, the molded product may become clouded under high temperature and high humidity. The blending amount is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 5 parts by mass, and particularly preferably 0.05 to 2 parts by mass with respect to 100 parts by mass of the block copolymer.

The method of forming the polymer composition by blending the above-mentioned compounding agent with the polymer used in the present invention is, for example, a state where the block copolymer is melted with a mixer, a twin-screw kneader, a roll, a Brabender, an extruder, or the like. And a method of kneading with a compounding agent, a method of dissolving and dispersing in an appropriate solvent and solidifying. When a twin-screw kneader is used, it is often used after being kneaded and usually extruded in the form of a strand in a molten state and cut into a pellet by a pelletizer.
[1-2.2] Fluorinated film 55
The fluorinated film 55 is a layer formed by performing a fluorination process on the molded part 50, and has a function of reducing the surface reflectance of the objective lens 37. The refractive index of the fluorinated film 55 with respect to d-line is 1.35 to 1.45, and the value of the refractive index can be measured by the surface reflectance. The layer thickness of the fluorinated film 55 (thickness from the surface 37a to the inside of the molding part 50) is preferably 50 to 300 nm. When the layer thickness exceeds 300 nm, the influence of interference fringes greatly depends on the wavelength of light, and even if the antireflection film 60 is formed thereon, it becomes difficult to exert its function, and conversely, the layer thickness is less than 50 nm. This is because it is difficult to sufficiently exert the function of the fluorinated film 55.
[1-2.3] Antireflection film 60
The antireflection film 60 is made of an inorganic material and basically has a two-layer structure. A first layer 61 is formed directly on the fluorinated film 55, and a second layer 62 is formed thereon.

The first layer 61 is a layer made of a high refractive index material having a refractive index of 1.7 or more, and preferably Ta ₂ O ₅ , a mixture of Ta ₂ O ₅ and TiO ₂ , ZrO ₂ , ZrO ₂ and TiO _2. And is composed of any mixture. The first layer 61 may be composed of TiO ₂ , Nb ₂ O ₃ , and HfO ₂ . The second layer 62 is a layer made of a low refractive index material having a refractive index of less than 1.7, and is preferably made of SiO ₂ and MgF ₂ .

In the objective lens 37, the first layer 61 and the second layer 62 may be alternately stacked on the first layer 61 and the second layer 62, and the antireflection film 60 may have a 2-7 layer structure as a whole. In this case, the layer in direct contact with the fluorinated film 55 may be a layer of high refractive index material (first layer 61) or a layer of low refractive index material (second layer), depending on the type of the molded part 50. Layer 62). In the present embodiment, the layer that is in direct contact with the fluorinated film 55 is a layer of a high refractive index material.

In the objective lens 37, the fluorinated film 55 and the antireflection film 60 are also formed on the back surface 37b in the same manner as the fluorinated film 55 and the antireflection film 60 are formed on the front surface 37a. The fluorinated film 55 and the antireflection film 60 are formed on both the front surface 37a and the back surface 37b. However, the objective lens 37 may not have the antireflection film 60.
[1-2.4] Method for Manufacturing Objective Lens 37 Next, a method for manufacturing the objective lens 37 will be described.

First, the above resin material is injection-molded on a mold under a certain condition to form a molded part 50 having a predetermined shape. Thereafter, a fluorination treatment is performed on the molding unit 50 to form a fluorinated film 55 on the molding unit 50.

In the fluorination treatment, the molded part 50 is exposed to a fluorine gas atmosphere, and a fluorinated film 55 is formed on the surface thereof. Thereby, the refractive index of the polymer material (resin) can be lowered, and the surface reflectance of the objective lens 37 can be lowered.

By appropriately selecting the fluorine gas concentration in the fluorine gas atmosphere and the temperature and time of exposure to the fluorine gas atmosphere, the fluorination rate and the film thickness of the fluorinated film 55 can be arbitrarily controlled, and the surface reflectance at a desired wavelength. Can be reduced.

Here, the fluorine gas atmosphere means being covered with a gas containing fluorine gas, and includes being covered with a mixed gas of fluorine gas and an inert gas such as nitrogen or argon.

Further, the concentration of the fluorine gas in the fluorine gas atmosphere can be appropriately selected according to the desired refractive index and the thickness of the fluorinated film 55.

Further, the molding part 50 is not particularly limited as long as it is a polymer composed of carbon and hydrogen as a constituent element of the resin and is a polymer composed of carbon and hydrogen in addition to the above example.

In addition, the constituent element of the additive whose addition amount is 5% or less with respect to the total mass, such as an antioxidant, an ultraviolet absorber, and a plasticizer added to the molded part 50 may be other than carbon and hydrogen. .

Further, even when a polymerization auxiliary material such as a catalyst or a reaction terminator used in manufacturing the molded part 50 remains, if the residual amount is less than 1% with respect to the total mass, its constituent elements Is not limited to carbon and hydrogen.

In the present embodiment, the molded part 50 is not particularly limited as long as the above conditions are satisfied. However, the above-described resin can be used in consideration of high transparency, high heat resistance, low water absorption, high purity, and low birefringence. More preferred is a polymer of the material.

When this polymer is exposed to fluorine gas of various concentrations diluted with nitrogen gas, for example, at a predetermined temperature and for a predetermined time, fluorine is gradually introduced into the molecule from the surface to the inside of the polymer material. The fluorine content of the material will increase.

The penetration depth of fluorine from the material surface and the fluorine content in the material after fluorine treatment vary depending on the concentration of fluorine gas during the fluorine treatment, the fluorine treatment temperature, and the fluorine treatment time.

There are no particular restrictions on these conditions, but when the fluorine concentration is high, the treatment time is long, the treatment temperature is high, the penetration depth of fluorine becomes deep, and the fluorine-containing polymer material after fluorine treatment contains The rate is high.

Since the refractive index of the fluorinated portion decreases as the fluorine content increases, the low-refractive fluorinated film 55 having a desired thickness can be formed by appropriately selecting the fluorine concentration, processing temperature, and processing time. Is possible.

However, if the fluorine concentration is extremely increased or the fluorine treatment is performed at an extremely high temperature for a long time, the molecule deteriorates. Therefore, the normal fluorine treatment conditions are a fluorine concentration of 1 ppm to 25% and a treatment temperature of 0 to 100. C. and a treatment time of 0.1 second to 120 minutes are preferred.

Thereafter, an antireflection film 60 is formed on the fluorinated film 55. Specifically, the first layer 61 is formed using a vapor deposition source that constitutes the first layer 61. For example, when a (Ta ₂ O ₅ + 5% TiO ₂ ) film is formed as the first layer 61, OA600 manufactured by OPTRAN can be used as the evaporation source and the evaporation source may be evaporated by electron gun heating. During vapor deposition, it is preferable to form a film while introducing O ₂ gas up to a pressure of 1.0 × 10 ⁻² Pa inside the vacuum vapor deposition apparatus and controlling the vapor deposition rate at 5 Å / sec. Then, the film forming temperature (temperature in the vapor deposition apparatus) is maintained within an appropriate temperature range.

Thereafter, in order to form the first layer 61 on the opposite surface of the molding portion 50, the molding portion 50 is reversed by the reversing mechanism inside the vapor deposition apparatus, and the first layer 61 is also formed on the opposite surface in the same manner as described above. (The same applies to the film formation on the back surface of the second layer 62.)

Thereafter, the second layer 62 is formed on the first layer 61 using the vapor deposition source constituting the second layer 62. For example, when a SiO ₂ film is formed as the second layer 62, O ₂ gas is introduced up to a pressure of 1.0 × 10 ⁻² Pa inside the vacuum vapor deposition apparatus, and the vapor deposition rate is controlled to 5 liters / sec. It is better to form the film while doing so. Then, the film forming temperature (temperature in the vapor deposition apparatus) is maintained within an appropriate temperature range.

The objective lens 37 is manufactured by the above process.
[2] Operation of Optical Pickup Device 30 Next, the operation of the optical pickup device 30 will be described.

Blue-violet light is emitted from the semiconductor laser oscillator 32 during an operation of recording information on the optical disc D or an operation of reproducing information recorded on the optical disc D. The emitted blue-violet light is transmitted through the collimator 33 and collimated into infinite parallel light, then transmitted through the beam splitter 34 and transmitted through the quarter wavelength plate 35. Furthermore, after passing through the blue-violet light aperture 36 and the objective lens 37, forms a converged spot on an information recording surface D ₂ through the protective substrate D ₁ of the optical disc D.

Violet light that formed the concentrated light spot is modulated by the information recording surface D ₂ of the optical disk D by the information bits, is reflected by the information recording surface D _2. Then, the reflected light is sequentially transmitted through the objective lens 37 and the diaphragm 36, the polarization direction is changed by the quarter wavelength plate 35, and the reflected light is reflected by the beam splitter 34. Thereafter, the reflected light passes through the sensor lens group 38 to be given astigmatism, is received by the sensor 39, and finally is photoelectrically converted by the sensor 39 to become an electrical signal.

Thereafter, such an operation is repeatedly performed, and the operation of recording information on the optical disc D and the operation of reproducing information recorded on the optical disc D are completed.

According to the above embodiment, the surface of the molded part 50 is fluorinated to form the fluorinated film 55, and the resin material of the molded part 50 has an alicyclic hydrocarbon structure, Since the number of tertiary carbons of the resin contains 3 or less, the interface between the resin portion layer not subjected to fluorination treatment and the resin portion layer subjected to fluorination treatment can be flattened. As a result, a decrease in optical performance due to the fluorination treatment can be prevented.

Further, since the thickness of the fluorinated film 55 is 50 to 300 nm, the antireflection function by the antireflection film 60 can be improved as compared with the case where the layer thickness exceeds 300 nm, and the layer thickness is less than 50 nm. Compared with the case, the antireflection function by the fluorinated film 55 can be improved.

Furthermore, the density of the resin material molded portion 50 is less than 1 g / cm ^3, as compared with the case of 1 g / cm ³ or more, to increase the rate of introduction of fluorine into the interior molding section 50 by the fluorination treatment it can. Accordingly, the interface between the resin portion layer that has not been fluorinated and the layer of the resin portion that has been fluorinated can be more reliably flattened, thereby more reliably preventing the optical performance from being deteriorated. be able to.

In the above embodiment, the optical element according to the present invention has been described as the objective lens 37, but other types and applications of optical elements may be used.

Hereinafter, the optical element according to the present invention will be described more specifically by giving examples and comparative examples. However, the present invention is not limited to the examples.
(1) Preparation of Samples As examples and comparative examples of the present invention, samples as shown in Tables 1 to 5 below were prepared. Hereinafter, each sample will be specifically described.

(1.1) Example 1
The inside of the stainless steel reactor equipped with a stirrer was sufficiently dried and purged with nitrogen. Thereafter, 300 parts by mass of dehydrated cyclohexane, 60 parts by mass of styrene and 0.38 parts by mass of dibutyl ether were charged into the reactor, and the n-butyllithium solution (15% hexane solution) 0 was added while stirring them at 60 ° C. .36 parts by mass was added to initiate the polymerization reaction.

Polymerization reaction is performed for 1 hour, and then the reaction solution is mixed with 8 parts by mass of styrene, 12 parts by mass of isoprene and 0.8 parts by mass of 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate. A monomer was added and the polymerization reaction was further performed for 1 hour, and then 0.2 parts by mass of isopropyl alcohol was added to the reaction solution to stop the reaction.

Next, 300 parts by mass of the polymerization reaction solution was transferred to a pressure-resistant reactor equipped with a stirrer, and as a hydrogenation catalyst, a silica-alumina supported nickel catalyst (manufactured by JGC Kagaku Kogyo Co., Ltd .: E22U, nickel supported amount 60). %) 10 parts by mass were added and mixed. The inside of the reactor was replaced with hydrogen gas, hydrogen was further supplied while stirring the solution, the temperature was set to 160 ° C., and then a hydrogenation reaction was performed at a pressure of 4.5 MPa for 8 hours.

After completion of the reaction, the reaction solution was filtered to remove the hydrogenation catalyst, 800 parts by mass of cyclohexane was added for dilution, and then the reaction solution was poured into 3500 parts by mass of isopropanol to precipitate a copolymer. Thereafter, this copolymer was filtered out and dried under reduced pressure at 80 ° C. for 48 hours to obtain “resin material 1”. The number of tertiary carbons per unit structure of the base resin in this “resin material 1” was 2, and the density of “resin material 1” was measured to be 0.94 g / cm ³ .

This “resin material 1” was dried at 70 ° C. for 6 hours to remove moisture, and then was injected with an injection molding machine at a cylinder temperature of 280 ° C., a mold temperature of 80 ° C., an injection speed of 30 mm / sec, and an injection pressure of 80 MPa. 85 objective lenses for optical pickup were molded.

Next, the objective lens is exposed to an atmosphere of 1.1 atm, normal temperature and F ₂ gas concentration for 5 minutes to subject the objective lens to fluorination treatment. The sample of Example 1 was used. Here, the film thickness of the obtained fluorinated film was 50 nm. Further, when the time for forming a 100 nm fluorinated film was measured under the same conditions (1.1 atm, normal temperature, F ₂ gas concentration 5%), it was 10 minutes (see Table 4).
(1.2) Example 2
In the sample of Example 1, the fluorination treatment time was 10 minutes (otherwise, it was the same as the sample of Example 1), and the objective lens thus produced was used as the sample of “Example 2”. Here, the film thickness of the obtained fluorinated film was 100 nm.
(1.3) Example 3
In the sample of Example 1, the fluorination treatment time was 30 minutes (otherwise, it was the same as the sample of Example 1), and the objective lens thus produced was used as the sample of “Example 3”. Here, the film thickness of the obtained fluorinated film was 300 nm.
(1.4) Comparative Example 1
The inside of the stainless steel reactor equipped with a stirrer was sufficiently dried and purged with nitrogen. Thereafter, 300 parts by mass of dehydrated cyclohexane, 60 parts by mass of 2,4-dimethylstyrene and 0.38 parts by mass of dibutyl ether were charged into the reactor. While stirring at 60 ° C., an n-butyllithium solution (15% Containing hexane solution) 0.36 parts by mass was added to initiate the polymerization reaction.

The polymerization reaction was carried out for 1 hour, and then 8 parts by mass of 2,4-dimethylstyrene, 12 parts by mass of isoprene and 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate 0.8 were added to the reaction solution. A mixed monomer consisting of parts by mass was added, and a polymerization reaction was further performed for 1 hour. Thereafter, 0.2 parts by mass of isopropyl alcohol was added to the reaction solution to stop the reaction.

Next, 300 parts by mass of the above polymerization reaction solution was transferred to a pressure-resistant reactor equipped with a stirrer, and as a hydrogenation catalyst, a silica-alumina supported nickel catalyst (manufactured by JGC Kagaku Kogyo Co., Ltd .: E22U, nickel supported amount 60). %) 10 parts by mass were added and mixed. The inside of the reactor was replaced with hydrogen gas, hydrogen was further supplied while stirring the solution, the temperature was set to 160 ° C., and then a hydrogenation reaction was performed at a pressure of 4.5 MPa for 8 hours.

After completion of the reaction, the reaction solution was filtered to remove the hydrogenation catalyst, 800 parts by mass of cyclohexane was added for dilution, and then the reaction solution was poured into 3500 parts by mass of isopropanol to precipitate a copolymer. Thereafter, this copolymer was filtered out and dried under reduced pressure at 80 ° C. for 48 hours to obtain “resin material 2”. In this “resin material 2”, the number of monomers having a large number of tertiary carbons per unit structure of the base resin is four, and the density of “resin material 2” was measured to be 0.97 g / cm ³ . .

This “resin material 2” was dried at 70 ° C. for 6 hours to remove moisture, and thereafter, with an injection molding machine, NA 0 .0 at a cylinder temperature of 280 ° C., a mold temperature of 80 ° C., an injection speed of 30 mm / sec, and an injection pressure of 80 MPa. 85 objective lenses for optical pickup were molded.

Next, the objective lens is exposed to an atmosphere of 1.1 atm, normal temperature, and F ₂ gas concentration of 6% for 6 minutes to subject the objective lens to fluorination treatment. The sample of Example 1 was used. Here, the film thickness of the obtained fluorinated film was 50 nm.
(1.5) Comparative Example 2
In the sample of Comparative Example 1, the fluorination treatment time was 11 minutes (otherwise, it was the same as the sample of Comparative Example 1), and the objective lens thus produced was used as the sample of “Comparative Example 2”. Here, the film thickness of the obtained fluorinated film was 100 nm.
(1.6) Comparative Example 3
In the sample of Comparative Example 1, the fluorination treatment time was 35 minutes (otherwise, it was the same as the sample of Comparative Example 1), and the objective lens thus produced was used as the sample of “Comparative Example 3”. Here, the film thickness of the obtained fluorinated film was 300 nm.
(1.7) Comparative Example 4
Ethylene and tetracyclo ^[4,4,0,1 ^{2,5, 1 7,10]} dodeca-3 random copolymer 100 parts by weight of the ene, pentaerythritol distearate 0.5 part by weight of a surfactant And 0.3 parts by mass of pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as a stabilizer were kneaded in a biaxial kneader “resin material 3 " The number of tertiary carbons per unit structure of the base resin in this “resin material 3” was 8, and the density of “resin material 3” was measured to be 1.04 g / cm ³ .

This “resin material 3” was dried at 70 ° C. for 6 hours to remove moisture, and thereafter, with an injection molding machine, NA 0 .0 at a cylinder temperature of 280 ° C., a mold temperature of 80 ° C., an injection speed of 30 mm / sec, and an injection pressure of 80 MPa. 85 objective lenses for optical pickup were molded.

Next, the objective lens was exposed to an atmosphere of 1.1 atm, normal temperature, and F ₂ gas concentration of 5% for 8 minutes to subject the objective lens to fluorination treatment. The sample of Example 4 was used. Here, the film thickness of the obtained fluorinated film was 50 nm.
(1.8) Comparative Example 5
In the sample of Comparative Example 4, the fluorination treatment time was 15 minutes (otherwise, it was the same as the sample of Comparative Example 4), and the objective lens thus produced was used as the sample of “Comparative Example 5”. Here, the film thickness of the obtained fluorinated film was 100 nm.
(1.9) Comparative Example 6
In the sample of Comparative Example 4, the fluorination treatment time was 50 minutes (otherwise, it was the same as the sample of Comparative Example 4), and the objective lens thus produced was used as the sample of “Comparative Example 6”. Here, the film thickness of the obtained fluorinated film was 300 nm.
(1.10) Examples 1 'to 3', Comparative Examples 1 'to 6'
Of the imaging system lens for 3M pixels constituted by four lenses, the second lens was molded from glass material K-BaSF12.

The first, third, and fourth lenses were molded and then fluorinated in the same manner as in Examples 1 to 3 and Comparative Examples 1 to 6 described above.

Then, an imaging system lens is configured by these four lenses, and samples of “Example 1 ′” to “Example 3 ′” and “Comparative Example 1 ′” to “Comparative Example 6 ′” are used.

Specifically, as in Example 1, the first, third, and fourth lenses are molded from “resin material 1”, and each lens is subjected to fluorination treatment for 5 minutes. The obtained imaging system lens was used as a sample of “Example 1 ′”. Here, the film thickness of the obtained fluorinated film was 50 nm, respectively.

Similarly to Example 2, the first, third, and fourth lenses were molded from “resin material 1”, and each lens was subjected to fluorination treatment for 10 minutes, and then combined with the second lens. The obtained imaging lens was used as a sample of “Example 2 ′”. Here, each film thickness of the obtained fluorinated film was 100 nm.

Similarly to Example 3, the first, third, and fourth lenses were molded from “resin material 1”, and each lens was subjected to a fluorination treatment for 30 minutes, and then combined with the second lens. The obtained imaging lens was used as a sample of “Example 3 ′”. Here, each film thickness of the obtained fluorinated film was 300 nm.

Similarly to Comparative Example 1, the first, third, and fourth lenses were molded from “resin material 2”, and each lens was subjected to fluorination treatment for 6 minutes, and then combined with the second lens. The obtained imaging lens was used as a sample of “Comparative Example 1 ′”. Here, the film thickness of the obtained fluorinated film was 50 nm, respectively.

Similarly to Comparative Example 2, the first, third, and fourth lenses were molded from “resin material 2”, and each lens was subjected to fluorination treatment for 11 minutes, and then combined with the second lens. The obtained imaging lens was used as a sample of “Comparative Example 2 ′”. Here, each film thickness of the obtained fluorinated film was 100 nm.

Similarly to Comparative Example 3, the first, third, and fourth lenses were molded from “resin material 2”, and each lens was subjected to fluorination treatment for 35 minutes, and then combined with the second lens. The obtained imaging lens was used as a sample of “Comparative Example 3 ′”. Here, each film thickness of the obtained fluorinated film was 300 nm.

Similarly to Comparative Example 4, the first, third, and fourth lenses are molded from “resin material 3”, each lens is subjected to fluorination treatment for 8 minutes, and then combined with the second lens to obtain a lens. The obtained imaging lens was used as a sample of “Comparative Example 4 ′”. Here, the film thickness of the obtained fluorinated film was 50 nm, respectively.

Similarly to Comparative Example 5, the first, third, and fourth lenses were molded from “resin material 3”, and each lens was fluorinated for 15 minutes, and then combined with the second lens. The obtained imaging lens was used as a sample of “Comparative Example 5 ′”. Here, each film thickness of the obtained fluorinated film was 100 nm.

Similarly to Comparative Example 6, the first, third, and fourth lenses were molded from “resin material 3”, and each lens was subjected to a fluorination treatment for 50 minutes, and then combined with the second lens. The obtained imaging lens was used as a sample of “Comparative Example 6 ′”. Here, each film thickness of the obtained fluorinated film was 300 nm.
(1.11) Example 4
In the sample of Example 1, the fluorination treatment time was 2 minutes (otherwise, it was the same as the sample of Example 1), and the objective lens thus produced was used as the sample of “Example 4”. Here, the film thickness of the obtained fluorinated film was 20 nm.
(1.12) Example 5
In the sample of Example 1, the fluorination treatment time was 60 minutes (otherwise, it was the same as the sample of Example 1), and the objective lens thus produced was used as the sample of “Example 5”. Here, the film thickness of the obtained fluorinated film was 500 nm.
(1.13) Example 6
100 parts by mass of bicyclo [2,2,1] hept-2-ene and 7.6 parts by mass of 1-hexene are dissolved in 300 parts by mass of toluene. Here, 2 parts by mass of diethylaluminum chloride solution and 0% of tungsten hexachloride are dissolved. 0.003 part by mass was added, and the mixture was stirred at 80 ° C. for 3 hours. After stirring, a large amount of methanol was put into the mixed solution to be solidified, and the solidified polymer was dried.

100 parts by mass of the obtained polymer was dissolved in tetrahydrofuran, 10 parts by mass of palladium / alumina was added thereto as a hydrogenation catalyst, and a hydrogenation reaction was carried out while heating and stirring at 170 ° C. under a pressure of 4 MPa for 4 hours. Thereafter, the catalyst was filtered to obtain “resin material 4”. The number of tertiary carbons per unit structure of the base resin in this “resin material 4” was two, and the density of “resin material 4” was measured to be 1.01 g / cm ³ .

This “resin material 4” was dried at 70 ° C. for 6 hours to remove moisture, and thereafter, with an injection molding machine, NA 0 .0 at a cylinder temperature of 280 ° C., a mold temperature of 80 ° C., an injection speed of 30 mm / sec, and an injection pressure of 80 MPa. 85 objective lenses for optical pickup were molded.

Next, 1.1 atm the objective lens, ambient temperature, by exposure for 12 minutes under an atmosphere of F ₂ gas concentration 5%, performed fluorination process on the objective lens, "implement the resulting objective lens The sample was “Example 6”. Here, the film thickness of the obtained fluorinated film was 100 nm. In “resin material 1”, under the same conditions (1.1 atm, room temperature, F ₂ gas concentration 5%), the formation time of the 100 nm fluorinated film was 10 minutes (see Table 4).
(1.14) Example 7
Six TiO ₂ layers and SiO ₂ layers were alternately formed as antireflection films on the fluorinated film in the sample of Example 1, and the obtained objective lens was used as a sample of “Example 7”.
(2) Sample evaluation (2.1) Aberration evaluation For each of the samples (objective lenses) of Examples 1 to 3 and 6 and Comparative Examples 1 to 6, the laser beam having a wavelength of 405 nm was transmitted before and after the fluorination treatment. When the aberration was measured and evaluated according to the following criteria, the results were as shown in Tables 1 and 4 above.

◎: No change before and after fluorination treatment ○: Change of 10 mλ or less before and after fluorination treatment ×: Change of greater than 10 mλ and less than 50 mλ before and after fluorination treatment XX: Before and after fluorination treatment (2.2) Evaluation of MTF that caused a change larger than 50 mλ For each sample (imaging system lens) of the manufactured Examples 1 ′ to 3 ′ and Comparative Examples 1 ′ to 6 ′, MATRIX manufactured by Nanotex Co., Ltd. When MTF was measured using a plus and evaluated according to the following criteria, it was as shown in Table 2 above.

○: MTF difference before and after fluorination treatment is less than 10% Δ: MTF difference before and after fluorination treatment is 10% or more and 30% or less ×: MTF difference before and after fluorination treatment is 30 (2.3) Evaluation of light resistance greater than% The samples (objective lenses) of Examples 1 to 5 and 7 prepared were irradiated with a laser of 20 mW and 405 nm at 80 ° C., and light resistance was evaluated according to the following criteria. As a result, the results were as shown in Tables 3 and 5 above.

◎: No change before and after laser irradiation of 5000 h.

○: No change before and after laser irradiation of 3000 h.
(2.4) Measurement of light transmittance The light transmittance at a wavelength of 450 nm was measured for the prepared samples (objective lenses) of Examples 1 and 7. As shown in Table 5 above, in Example 1, it was 97%. In Example 7, it was 99%.
(3) Summary From the results in Table 1, it can be seen that the samples of Examples 1 to 3 prevent the occurrence of aberration due to the fluorination treatment as compared with the samples of Comparative Examples 1 to 6.

Also, from the results in Table 2, it can be seen that in the samples of Examples 1 'to 3', the decrease in MTF due to the fluorination treatment is prevented as compared with the samples of Comparative Examples 1 'to 6'.

From these, the surface of the optical element (molded part) molded with a resin material having a cycloaliphatic hydrocarbon structure and containing a resin having three or less tertiary carbons in the unit structure is fluorinated. It can be seen that deterioration of the optical performance is prevented.

In addition, from the results of Table 4, it can be seen that if the density of the resin material is less than 1 g / cm ³ , the optical performance deterioration due to the fluorination treatment can be more reliably prevented.

Also, from the results in Table 3, it can be seen that if the thickness of the fluorinated film is 50 to 300 nm, the light resistance is improved.

DESCRIPTION OF SYMBOLS 30 Optical pick-up apparatus 32 Semiconductor laser oscillator 33 Collimator 34 Beam splitter 35 1/4 wavelength plate 36 Diaphragm 37 Objective lens 37a Front surface 37b Back surface 38 Sensor lens group 39 Sensor 40 Two-dimensional actuator 50 Molding part 55 Fluorinated film 60 Antireflection film 61 First layer 62 Second layer D Optical disc D ₁ Protective substrate D ₂ Information recording surface

Claims

An optical element having a molded part molded from a resin material,
The resin material is
A resin having an alicyclic hydrocarbon structure, wherein the number of tertiary carbons in the unit structure is 3 or less,
The molded part is on the surface,
An optical element comprising a layer containing a resin in which at least a part of hydrogen constituting the alicyclic hydrocarbon structure is substituted with fluorine.
The optical element according to claim 1,
An optical element having a thickness of the fluorinated film of 50 to 300 nm.
The optical element according to claim 1 or 2,
The optical element characterized in that the density of the resin material is less than 1 g / cm 3 .
The optical element according to any one of claims 1 to 3,
An optical element, wherein an antireflection coating made of an inorganic material is provided on the fluorinated film.
The optical element according to any one of claims 1 to 4,
The numerical aperture NA on the image side is 0.8 or more,
An optical element that is an objective lens of an optical pickup device.
An optical pickup device comprising the optical element according to any one of claims 1 to 5 as an objective lens.