JPWO2006054462A1 - Optical element and optical pickup device - Google Patents

Abstract

An optical element, a repeating unit (a) having an alicyclic structure represented by formula (1), and a chain represented by formula (2) and / or formula (3) and / or formula (4) The repeating unit (b) having a hindered amine structure represented by formula (5) and a chain unit (c) having a hindered amine structure represented by the formula (5) in the side chain, and the total of the repeating unit (a) and the repeating unit (b) An alicyclic hydrocarbon copolymer having a content of 90% by weight or more and a repeating unit (b) content of 1% by weight or more and less than 10% by weight or the alicyclic hydrocarbon-based copolymer It is molded using a resin composition containing coalescence.

Description

  The present invention relates to an optical element made of plastic and an optical pickup device to which the optical element is applied.

  2. Description of the Related Art Conventionally, information devices such as players, recorders, and drives that read and record information on an optical information recording medium (hereinafter abbreviated as a medium) such as MO, CD, and DVD are provided with an optical pickup device. The optical pickup device includes an optical element unit that irradiates a medium with light having a predetermined wavelength emitted from a light source, and receives the reflected light with a light receiving element. The optical element unit receives the light from a reflection layer or a light receiving medium of the medium. An optical element such as a lens for condensing light by the element is included.

  The optical element of the optical pickup device is preferably made of plastic as a material in that it can be manufactured at low cost by means such as injection molding. As plastics applicable to optical elements, alicyclic hydrocarbon copolymers and the like are known (for example, see Patent Document 1).

By the way, in recent years, as a medium capable of recording information at a higher density than CD and DVD, Blu-ray which records and reproduces information at a shorter wavelength than that of CD (λ = 780 nm) and DVD (λ = 635, 650 nm). Development of new media such as ray discs and information devices for reading and writing information on these media is underway.
JP 2001-48924 A

  However, in so-called next-generation DVDs such as Blu-ray Discs, light having a wavelength of around 400 nm is used for recording and reproducing information. In the case of Patent Document 1, the optical element is irradiated with light having such a short wavelength. As a result, the optical element itself becomes cloudy or the life of the product is shortened due to deterioration of characteristics such as a change in refractive index, so that the optical element may need to be replaced.

  Accordingly, an object of the present invention is to provide an optical element capable of improving the light stability and maintaining the characteristics for a long time, and an optical pickup device having a good pickup characteristic using the optical element. That is.

In order to solve the above-described problem, the optical element according to Item 1 is
The repeating unit (a) having an alicyclic structure represented by the following formula (1), and a chain structure represented by the following formula (2) and / or the following formula (3) and / or the following formula (4) A repeating unit (b) and a chain unit (c) having a hindered amine structure represented by the following formula (5) in the side chain,
An alicyclic structure in which the total content of the repeating unit (a) and the repeating unit (b) is 90% by weight or more, and the content of the repeating unit (b) is 1% by weight or more and less than 10% by weight. It is characterized by being molded using a hydrocarbon-based copolymer or a resin composition containing the alicyclic hydrocarbon-based copolymer.

[In Formula (1), X is an alicyclic hydrocarbon group, and in Formula (1), Formula (2), Formula (3) and Formula (4), R1 to R13 are each independently a hydrogen atom, 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, a cyano group, an amide group, an imide group, or a silyl group), and in formula (5), R14 to R19 each independently represents a hydrogen atom or an alkyl group, Y Represents an alkylene group having 1 to 10 carbon atoms or an ester bond. ]
The invention according to Item 2 is the optical element according to Item 1,
The alicyclic hydrocarbon copolymer contains at least one stabilizer selected from a phenol stabilizer, a hindered amine stabilizer, a phosphorus stabilizer, and a sulfur stabilizer. It is characterized by.

The invention according to Item 3 is the optical element according to Item 1 or 2,
The melt index (MI) value of the alicyclic hydrocarbon copolymer or the resin composition measured under the conditions of a temperature of 260 ° C. and a load of 2.16 kg is 20 <MI (g / 10 minutes) <60. In range
It is characterized in that a predetermined fine structure is provided on at least one optical surface.

The invention according to item 4,
An optical pickup device for reproducing and / or recording information on an optical information recording medium,
A light source that emits light;
An optical element unit that irradiates the optical information recording medium with light emitted from the light source and / or collects light reflected by the optical information recording medium, and
The optical element unit is
The repeating unit (a) having an alicyclic structure represented by the following formula (1), and a chain structure represented by the following formula (2) and / or the following formula (3) and / or the following formula (4) Of the repeating unit (b) and a chain unit (c) having a hindered amine structure represented by the following formula (5) in the side chain, and the repeating unit (a) and the repeating unit (b) An alicyclic hydrocarbon copolymer having a total content of 90% by weight or more and a content of the repeating unit (b) of 1% by weight or more and less than 10% by weight or the alicyclic hydrocarbon system An optical element formed by using a resin composition containing a copolymer is provided.

[In Formula (1), X is an alicyclic hydrocarbon group, and in Formula (1), Formula (2), Formula (3) and Formula (4), R1 to R13 are each independently a hydrogen atom, 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, a cyano group, an amide group, an imide group, or a silyl group), and in formula (5), R14 to R19 each independently represents a hydrogen atom or an alkyl group, Y Represents an alkylene group having 1 to 10 carbon atoms or an ester bond. ]
The invention according to Item 5 is the optical pickup device according to Item 4,
The light source emits light having a wavelength of 390 to 420 [nm].

  According to the invention of Item 1, the alicyclic hydrocarbon copolymer in which the chain unit having a hindered amine structure in the side chain is directly bonded to the polymer molecular chain or the alicyclic hydrocarbon copolymer is included. Since it is molded using the resin composition, bleeding out of the hindered amine portion having a light stabilizing function is suppressed, and the hindered amine is uniformly dispersed in the resin composition, for example, at a wavelength of 405 nm. Even when irradiation with light having a short wavelength is continuously received, deterioration of the optical element such as white turbidity and refractive index fluctuation can be effectively suppressed. That is, the light stability of the optical element can be improved, and the characteristics can be maintained for a long time.

  According to the invention described in Item 2, various stabilizers are appropriately selected from a phenol stabilizer, a hindered amine stabilizer, a phosphorus stabilizer, and a sulfur stabilizer, and an alicyclic hydrocarbon copolymer or By adding to the resin composition containing the alicyclic hydrocarbon copolymer, it is possible to more synergistically suppress fluctuations in the optical characteristics of the molded optical element.

  According to the invention described in item 3, it is a matter of course that the same effect as that of the invention described in item 1 or 2 can be obtained. In particular, the alicyclic measurement is performed under conditions of a temperature of 260 ° C. and a load of 2.16 kg. The melt index (MI) value of the hydrocarbon copolymer or resin composition is in the range of 20 <MI (g / 10 minutes) <60, and a predetermined microstructure is provided on at least one optical surface. That is, since the melt index is in a range suitable for a molding method such as injection molding, the molten alicyclic hydrocarbon copolymer or resin composition has appropriate fluidity. When the element is molded, the molten alicyclic hydrocarbon copolymer or resin composition reaches the tip of the part corresponding to the fine structure, and thus the formed optical element is formed with high accuracy. Thus, a fine structure is provided.

  According to the invention described in Item 4, the optical element is an alicyclic hydrocarbon copolymer in which a chain unit having a hindered amine structure in the side chain is directly bonded to a polymer molecular chain, or the alicyclic hydrocarbon. Since it is molded using a resin composition containing a copolymer, bleeding out of hindered amine sites having a light stabilizing function is suppressed, and hindered amine is uniformly dispersed in the resin composition, for example, Even if irradiation with light having a short wavelength such as a wavelength of 405 nm is continuously received, deterioration such as white turbidity and refractive index fluctuation of the optical element can be effectively suppressed. That is, the light stability of the optical element can be improved, and the characteristics can be maintained for a long time.

  Accordingly, for example, information can be read and written with good pickup characteristics over a long period of time on an optical information recording medium having a high information density such as a Blu-ray Disc, and the optical pickup device has high reliability. Can be obtained.

  According to the invention described in item 5, the wavelength of light emitted from the light source is 390 to 420 [nm]. That is, for example, even when light having a wavelength in the range of 390 to 420 [nm] corresponding to an optical information recording medium having a high information density such as a Blu-ray Disc is transmitted, the optical element has a hindered amine structure as a side chain. Is formed using an alicyclic hydrocarbon copolymer in which the chain unit is directly bonded to the polymer molecular chain or a resin composition containing the alicyclic hydrocarbon copolymer. Degradation of the optical element such as rate fluctuation can be prevented. Thereby, the lifetime of the optical element can be extended, and a highly reliable optical pickup device can be obtained.

1 is a side view schematically showing an optical pickup device according to the present invention. It is a sectional side view of the objective lens illustrated as an optical element concerning the present invention. It is a sectional side view of the objective lens illustrated as an optical element concerning the present invention. It is a sectional side view of the objective lens illustrated as an optical element concerning the present invention. It is a sectional side view of the objective lens illustrated as an optical element concerning the present invention. It is a sectional side view of the objective lens illustrated as an optical element concerning the present invention. It is a sectional side view of a hologram optical element and an objective lens exemplified as an optical element according to the present invention.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

  The plastic optical lens of the present invention includes an alicyclic hydrocarbon copolymer having a repeating unit having an alicyclic structure and a chain unit having a hindered amine structure in the side chain, or the alicyclic hydrocarbon copolymer. It shape | molds using the resin composition containing this. In the alicyclic hydrocarbon copolymer preferred in the present invention, the repeating unit having an alicyclic structure has a repeating unit (a) having an alicyclic structure represented by the following formula (1), and the following formula (2 ) And / or the repeating unit (b) having a chain structure represented by the following formula (3) and / or the following formula (4) so that the total content is 90% by mass or more, and further the repeating unit. The content of (b) is 1% by mass or more and less than 10% by mass.

  In formula (1), formula (2), formula (3) and formula (4), R1 to R13 are each independently a hydrogen atom, a chain hydrocarbon group, a halogen atom, an alkoxy group, a hydroxy group, an ether group, Substituted with 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, amide group, imide group, or silyl group) Represents a chain hydrocarbon group or the like. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the chain hydrocarbon group substituted with a polar group include a halogenated alkyl group having 1 to 20, preferably 1 to 10, more preferably 1 to 6 carbon atoms. As the chain hydrocarbon group, for example, an alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms: 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms, more preferably 2 to 2 carbon atoms. 6 alkenyl groups.

  X in the 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. It is. Birefringence can be reduced by setting the number of carbon atoms constituting the alicyclic structure within this range. The alicyclic structure is not limited to a monocyclic structure, and may be a polycyclic structure such as a norbornane ring or a dicyclohexane ring.

Particularly, in the alicyclic hydrocarbon copolymer, the chain of the repeating unit (a) is represented by the relation A ≦ 0.3 × B [where A = (weight of the chain of repeating unit having an alicyclic structure). Average molecular weight). B = (weight average molecular weight (Mw) of alicyclic hydrocarbon-based copolymer × (number of repeating units having alicyclic structure / number of all repeating units constituting alicyclic hydrocarbon-based copolymer))) It is preferable to satisfy.
(Alicyclic hydrocarbon copolymer)
The alicyclic hydrocarbon group may have a carbon-carbon unsaturated bond, but its content 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 addition, the above formula (3) has a carbon-carbon unsaturated bond in the main chain, and the above formula (4) has a carbon-carbon saturated bond in the main chain. When heat resistance is strongly required, the content of unsaturated bonds is usually 10% or less, preferably 5% or less, more preferably 3% or less, of all carbon-carbon bonds constituting the main chain.

  In particular, among the repeating units represented by the formula (1), the repeating unit represented by the following formula (6) 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 (7) 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 (8) is excellent in terms of heat resistance and low water absorption.

  Among the repeating units represented by the formula (4), the repeating unit represented by the following formula (9) is excellent in terms of heat resistance and low water absorption.

  In formula (6), formula (7), formula (8) and formula (9), Ra, Rb, Rc, Rd, Re, Rf, Rg, Rh, Ri, Rj, Rk, Rl, Rm, Rn are Each independently represents a hydrogen atom or a lower chain hydrocarbon group, and 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, the repeating unit (a) having an alicyclic structure represented by the formula (1) in the alicyclic hydrocarbon-based copolymer, the formula (2) and / or the formula (3) and The total content of the chain-structured repeating unit (b) represented by the formula (4) is usually 90% or more, preferably 95% or more, more preferably 97% or more, based on weight. 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 weight 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.

  The molecular weight of the alicyclic hydrocarbon copolymer according to the present invention is a polystyrene (or polyisoprene) equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (hereinafter referred to as GPC), The range is from 000 to 1,000,000, preferably from 5,000 to 500,000, more preferably from 10,000 to 300,000, and most preferably from 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. .
(Hindered amine-containing chain units)
The hindered amine-containing chain unit copolymerized with the alicyclic hydrocarbon-based copolymer is represented by the following formula (5).

  In the above formula (5), R14 to R19 are each independently a hydrogen atom or a methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, t-butyl group, pentyl group, hexyl group, etc. Represents an alkyl group, and Y represents an alkylene group having 1 to 10 carbon atoms or an ester bond.

  The amount copolymerized in the alicyclic hydrocarbon-based copolymer is 0.01 to 50 parts by mass of the hindered amine-containing chain unit with respect to 100 parts by mass of the repeating unit having an alicyclic structure.

When molding using an alicyclic hydrocarbon copolymer having a hindered amine-containing chain unit, the copolymer can be used alone or blended with an alicyclic hydrocarbon copolymer that does not contain a hindered amine moiety. It may be a composition, and further may be used as a resin composition to which additives such as various stabilizers are added as necessary.
(Method for producing alicyclic hydrocarbon-based copolymer)
The production method for producing the alicyclic hydrocarbon-based copolymer is as follows: (1) copolymerizing an aromatic vinyl compound with another monomer copolymerizable with the main chain and aromatic ring carbon-carbon 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.

  Further, when copolymerizing hindered amine-containing chain units, a polymerizable hindered amine compound having a vinyl group may be copolymerized with the monomer, and in this case, if it can be copolymerized with the monomer, You may use individually or in combination of 2 or more types.

  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-based copolymer described in the document Macromolecules 1983, 16, 1925-1928. This can be confirmed by a method of measuring the molecular weight of the extracted aromatic vinyl chain after 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, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, monochlorostyrene , Dichlorostyrene, monofluorostyrene, 4-phenylstyrene and the like, and 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, norbornylethylene, dicyclohexylethylene, α -Methylcyclohexylethylene, α-t-butylcyclohexylethylene, cyclopentenylethylene, cyclohexenylethylene, cycloheptenylethylene, cyclooctenylethylene, cyclodecenylethylene, norbornenylethylene, α-methylcyclohexenylethylene, and α -T-butylcyclohexenylethylene etc. are mentioned, Among these, cyclohexylethylene and (alpha) -methylcyclohexylethylene are preferable.

  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-methoxycarboni (Meth) acrylic acid such as ethylene (acrylic acid methyl ester), 1-ethoxycarbonylethylene (acrylic acid ethyl ester), 1-propoxycarbonylethylene (acrylic acid propyl ester), 1-butoxycarbonylethylene (acrylic acid butyl ester) Ester monomers, 1-carboxyethylene (acrylic acid), 1-carboxy-1-methylethylene (methacrylic acid), unsaturated fatty acid monomers such as maleic anhydride, and the like are mentioned, among which chain olefin monomers are preferable, 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.

  Specific examples of the polymerizable hindered amine compound include 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4- (5 -Hexenyl) -2,2,6,6-tetramethylpiperidine and the like are preferably used.

  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.

  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, the total amount of monomers used is usually 0.01 wt% to 60 wt%, preferably 0.02 wt% to 20 wt%, more preferably 0.05 wt% to 10 wt%. 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 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 rate of the initial monomer to reach 90% is T, and the ratio (%) of the initial monomer to the total used monomer 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 monomer are determined so that it is 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. As radical initiators, benzoyl peroxide, lauroyl peroxide, organic peroxides such as 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 the anionic polymerization include monoorganolithium such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, and phenyllithium, dilithiomethane, 1,4-diobane, and 1,4-dilithio. 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 long chain of one component) from being used, and 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 Tertiary amine compounds such as potassium; t-amyl oxide, alkali metal alkoxide compounds such as 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.

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 conducting 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 supported amount of the catalyst is usually 0.01 to 80% by weight, preferably 0. The range is from 05 to 60% by weight. 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.

  As an example of the organometallic complex catalyst, a metal complex such as a γ-dichloro-π-benzene complex, a dichloro-tris (triphenylphosphine) complex, a hydrido-chloro-triphenylphosphine) complex of each of the above metals is used. 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 the basis of weight with respect to the polymer. 0.05 to 50 parts, more preferably 0.1 to 30 parts.

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

The hydrogenation rate of the hydride obtained in this manner is determined by ¹ H-NMR, as determined by ¹ H-NMR, the main chain carbon-carbon unsaturated bond, the aromatic ring carbon-carbon double bond, the unsaturated ring carbon- All of the carbon 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.
(Resin composition)
The plastic optical element of the present invention may be molded using a resin composition containing various stabilizers in the alicyclic hydrocarbon-based copolymer.

  Examples of the stabilizer according to the present invention include a phenol stabilizer, a hindered amine stabilizer, a phosphorus stabilizer, and a sulfur stabilizer. By blending these stabilizers in an appropriate amount of resin, synergistically enhance the deterioration-inhibiting effect against short-wavelength light irradiation with hindered amine moieties bonded in the resin molecule without lowering transparency and low water absorption. Therefore, a more reliable optical pickup device can be obtained.

  As a preferable phenol-based stabilizer, conventionally known ones can be used, for example, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2 , 4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate and the like, and JP-A Nos. 63-179953 and 1-168643. Acrylate compounds described in Japanese Patent Publication No. 1; octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2′-methylene-bis (4-methyl-6-tert-butylphenol) ), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenylpropionate) methane [ie, pentaerythrmethyl] -Tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenylpropionate)), triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate) Alkyl-substituted phenolic compounds such as 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1,3,5-triazine, 4-bisoctylthio-1, 3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3,5-tria Triazine group-containing phenol compounds such as emissions and the like.

  Preferred hindered amine stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ((2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-benzyloxy-2) , 2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6, 6-Pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1-acryloyl-2,2, , 6-Tetramethyl-4-piperidyl) 2,2-bis (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6- Pentamethyl-4-piperidyl) decanedioate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -1- [2- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- ( 2,2,6,6-tetramethyl-4-piperidyl) amino-N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide, tetrakis (2,2,6,6-tetramethyl -4-pipe Jill) 1,2,3,4-butane tetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, and the like.

  Further, the preferable phosphorus stabilizer is not particularly limited as long as it is a substance usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonyl). Phenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9 , 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the like; 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) Phosphite), 4,4′isopropylidene-bis (phenyl-di-alkyl (C12-C15) phos Aito) and the like diphosphite compounds such as. Among these, monophosphite compounds are preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.

  Preferred sulfur stabilizers include, for example, dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3- Thiodipropionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate, 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, etc. Is mentioned.

  These stabilizers can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within the range not impairing the object of the present invention. The amount is usually 0.001 to 5 parts by weight, preferably 0.01 to 1 part by weight based on 100 parts by weight of the polymer.

  In the present invention, at least one compound selected from the group consisting of the alicyclic hydrocarbon-based copolymer, (1) a soft polymer, (2) an alcoholic compound, and (3) an organic or inorganic filler. A resin composition comprising the agent is provided. By blending these compounding agents, it is possible to prevent white turbidity in a high temperature and high humidity environment for a long time without degrading various properties such as transparency, low water absorption, and mechanical strength.

Among these, (1) a soft polymer and (2) an alcoholic compound are excellent in the effect of preventing white turbidity in a high-temperature and high-humidity environment and the transparency of the resulting resin composition. (1) Soft polymer The soft polymer used for this invention is a polymer which usually has Tg of 30 degrees C or less, and when multiple Tg exists, at least lowest Tg should just be 30 degrees C or less.
(1) Soft polymer Specific examples of the soft polymer include, for example, liquid polyethylene, polypropylene, poly-1-butene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, ethylene / propylene / Olefin soft polymers such as diene copolymers (EPDM) and ethylene / propylene / styrene copolymers; isobutylene soft polymers such as polyisobutylene, isobutylene / isoprene rubber, isobutylene / styrene copolymers; 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 copolymers, isoprene / styrene block copolymers, diene soft polymers such as styrene / isoprene / styrene block copolymers; silicon-containing soft weights such as dimethylpolysiloxane, diphenylpolysiloxane, and dihydroxypolysiloxane Polymer; Soft polymer comprising α, β-unsaturated acid such as polybutyl acrylate, polybutyl methacrylate, polyhydroxyethyl methacrylate, polyacrylamide, polyacrylonitrile, butyl acrylate / styrene copolymer; polyvinyl alcohol, polyvinyl acetate, Soft polymers composed of unsaturated alcohols such as polyvinyl stearate and vinyl acetate / styrene copolymers and amines or acyl derivatives or acetals thereof; polyethylene oxide, polypropylene oxide Epoxy soft polymers such as epoxy and epichlorohydrin rubbers; Fluorine soft polymers such as vinylidene fluoride rubber and tetrafluoroethylene-propylene rubber; natural rubber, polypeptides, proteins, polyester thermoplastic elastomers, Other soft polymers such as vinyl chloride thermoplastic elastomers and polyamide thermoplastic elastomers may be mentioned. These soft polymers may have a cross-linked structure or may have a functional group introduced by a modification reaction.

Of the above-mentioned soft polymers, diene-based soft polymers are preferable. In particular, hydrides obtained by hydrogenating carbon-carbon unsaturated bonds of the soft polymers are excellent in terms of rubber elasticity, mechanical strength, flexibility, and dispersibility.
(2) Alcoholic Compound The alcoholic compound is a compound having at least one non-phenolic hydroxyl group in the molecule, and preferably has at least one hydroxyl group and at least one ether bond or ester bond. Specific examples of such compounds include, for example, dihydric or higher polyhydric alcohols, more preferably trihydric or higher polyhydric alcohols, and even more preferably one of the hydroxyl groups of a polyhydric alcohol having 3 to 8 hydroxyl groups is an ether. Examples thereof include alcoholic ether compounds and alcoholic ester compounds that have been converted into or esterified.

  Examples of the dihydric or higher polyhydric alcohol include polyethylene glycol, glycerol, trimethylolpropane, pentaerythritol, diglycerol, triglycerol, dipentaerythritol, 1,6,7-trihydroxy-2,2-di (hydroxy). Methyl) -4-oxoheptane, sorbitol, 2-methyl-1,6,7-trihydroxy-2-hydroxymethyl-4-oxoheptane, 1,5,6-trihydroxy-3-oxohexanepentaerythritol, tris (2-Hydroxyethyl) isocyanurate and the like can be mentioned, and in particular, a trihydric or higher polyhydric alcohol, more preferably a polyhydric alcohol having 3 to 8 hydroxyl groups. In the case of obtaining an alcoholic ester compound, glycerol, diglycerol, triglycerol or the like capable of synthesizing an alcoholic ester compound containing α, β-diol is preferable.

Examples of such alcoholic compounds include glycerol monostearate, glycerol monolaurate, glycerol monobehenate, diglycerol monostearate, glycerol distearate, glycerol dilaurate, pentaerythritol monostearate, and pentaerythritol monolaurate. , Pentaerythritol monobeherate, pentaerythritol distearate, pentaerythritol dilaurate, pentaerythritol tristearate, dipentaerythritol distearate, and the like; 3- (octyloxy) -1,2-propane Diol, 3- (decyloxy) -1,2-propanediol, 3- (lauryloxy) -1,2-propanediol, 3- (4-nonylphenyl) Xy) -1,2-propanediol, 1,6-dihydrooxy-2,2-di (hydroxymethyl) -7- (4-nonylphenyloxy) -4-oxoheptane, p-nonylphenyl ether and formaldehyde Alcoholic ether compounds obtained by reaction of condensates with glycidol, alcoholic ether compounds obtained by reaction of condensates of p-octylphenyl ether and formaldehyde with glycidol, condensates of p-octylphenyl ether and dicyclopentadiene and glycidol And alcoholic ether compounds obtained by the above reaction. These polyhydric alcohol compounds are used alone or in combination of two or more. Although the molecular weight of these polyhydric alcohol compounds is not particularly limited, those having a molecular weight of usually 500 to 2000, preferably 800 to 1500, have little decrease in transparency.
(3) Organic or inorganic filler Organic filler As the organic or inorganic filler organic filler, ordinary organic polymer particles or crosslinked organic polymer particles can be used, for example, polyolefins such as polyethylene and polypropylene; polyvinyl chloride, poly Halogen-containing vinyl polymers such as vinylidene chloride; polymers derived from α, β-unsaturated acids such as polyarylate and polymethacrylate; polymers derived from unsaturated alcohols such as polyvinyl alcohol and polyvinyl acetate; Polymers derived from ethylene oxide or bisglycidyl ether; aromatic condensation polymers such as polyphenylene oxide, polycarbonate, polysulfone; polyurethane; polyamide; polyester; aldehyde / phenolic resin; Particles or crosslinked particles such compounds can be mentioned.

  Examples of the inorganic filler include Group 1 element compounds such as lithium fluoride and borax (sodium borate hydrate); Group 2 element compounds such as magnesium carbonate, magnesium phosphate, calcium carbonate, strontium titanate, and barium carbonate; Titania), Group 4 element compounds such as titanium monoxide; Group 6 element compounds of molybdenum dioxide and molybdenum trioxide; Group 7 element compounds such as manganese chloride and manganese acetate; Group 8-10 element compounds such as cobalt chloride and cobalt acetate Group 11 element compounds such as cuprous iodide; Group 12 element compounds such as zinc oxide and zinc acetate; Group 13 such as aluminum oxide (alumina), aluminum fluoride, aluminosilicate (alumina silicate, kaolin, kaolinite) Elemental compounds: silicon oxide (silica, silica gel), graphite, Bon, graphite, Group 14 element compound such as glass; kernal stones, kainite, mica (mica, Kin'unmo) include particles of natural minerals, such as Bairosu ore.

The compounding amount of the compounds (1) to (3) is determined depending on the combination of the compound blended with the alicyclic hydrocarbon copolymer, but generally, if the compounding amount is too large, the glass transition temperature of the composition or Transparency is greatly reduced, making it unsuitable for use as an optical material. 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 usually 0.01 to 10 parts by weight, preferably 0.02 to 5 parts by weight, particularly preferably 0.05 to 2 parts by weight with respect to 100 parts by weight of the alicyclic hydrocarbon-based copolymer. It mixes in the ratio. When the blending amount is too small, the effect of preventing white turbidity in a high temperature and high humidity environment cannot be obtained.
(Other ingredients)
In the resin composition of the present invention, if necessary, as other compounding agents, ultraviolet absorbers, light stabilizers, near infrared absorbers, coloring agents such as dyes and pigments, lubricants, plasticizers, antistatic agents, A fluorescent brightening agent or the like can be blended, and these can be used alone or in admixture of two or more, and the blending amount is appropriately selected within a range that does not impair the object of the present invention.
(Molding material)
The resin composition of the present invention can be obtained by appropriately mixing the above components. The mixing method is not particularly limited as long as each component is sufficiently dispersed in the hydrocarbon polymer. For example, the resin is melted in a mixer, a twin-screw kneader, a roll, a Brabender, an extruder, or the like. And a method of dissolving and dispersing in a suitable solvent and solidifying. When a twin-screw kneader is used, it is often used as a molding material that is usually extruded after being kneaded into a rod shape in a molten state, cut into an appropriate length with a strand cutter, and pelletized.

  The resin composition preferably has a melt index MI measured under conditions of a temperature of 260 ° C. and a load of 2.16 kg in a range of 20 <MI (g / 10 minutes) <60. Here, the measuring method of MI is based on ASTM D1238. The MI is more preferably 30 <MI (g / 10 minutes) <60.

  Here, the MI is a known method such as control of crystallinity by selection of the composition ratio of structural units each derived from α-olefin and cyclic olefin, and the addition of a plasticizer. Can be adjusted.

Examples of the plasticizer to be added include bis (2-ethylhexyl) adipate, bis (2-butoxyethyl) adipate, bis (2-ethylhexyl) azelate, dipropylene glycol dibenzoate, tri-n-butyl citrate, Tri-n-butylacetyl acid, epoxidized soybean oil, 2-ethylhexyl epoxidized tall oil, chlorinated paraffin, tri-2-ethylhexyl phosphate, tricresyl phosphate, tert-butylphenyl phosphate, tri-2 phosphate -Ethylhexyl diphenyl, dibutyl phthalate, diisohexyl phthalate, diheptyl phthalate, dinonyl phthalate, diundecyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, diisodecyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, phthalate acid Known materials such as cyclohexyl, di-2-ethylhexyl sebacate, tri-2-ethylhexyl trimellitic acid, Santizer 278, Paraplex G40, Drapex 334F, Plastolein 9720, Mesamol, DNODP-610, HB-40, etc. are applicable. . The selection of the plasticizer and the addition amount are appropriately performed on the condition that the permeability of the cyclic olefin and the resistance to environmental changes are not impaired.
(Plastic optical element)
The plastic optical element according to the present invention is obtained by molding a molding material comprising the alicyclic hydrocarbon copolymer or resin composition. The molding method is not particularly limited, but melt molding is preferable in order to obtain an optical element excellent in characteristics such as low birefringence, mechanical strength, and dimensional accuracy. Examples of the melt molding method include press molding, extrusion molding, and injection molding, and injection molding is preferable from the viewpoint of moldability and productivity. The molding conditions are appropriately selected depending on the purpose of use or the molding method. For example, the resin temperature in injection molding is usually selected in the range of 150 to 400 ° C., preferably 200 to 350 ° C., more preferably 230 to 330 ° C. The If the resin temperature is too low, fluidity will deteriorate, causing sink marks and distortion in the molded product. If the resin temperature is too high, silver streaks will occur due to thermal decomposition of the resin, and the optical element will turn yellow. Defects may occur.

  The plastic optical element according to the present invention can be used in various forms such as a spherical shape, a rod shape, a plate shape, a cylindrical shape, a tubular shape, a tubular shape, a fibrous shape, a film shape or a sheet shape, and has a low birefringence. Excellent in transparency, mechanical strength, heat resistance and low water absorption.

  Specific examples of the plastic optical element include the following. As an optical lens and an optical prism, an imaging lens of a camera; a lens such as a microscope, an endoscope, a telescope lens; an all-light transmission lens such as a spectacle lens; a CD, a CD-ROM, a WORM (recordable optical disk), an MO (Optical optical discs that can be rewritten; magneto-optical discs), pickup lenses for optical discs such as MD (mini discs), DVDs (digital video discs); laser scanning system lenses such as fθ lenses and sensor lenses for laser beam printers; Examples include finder type prism lenses. Examples of optical disc applications include CD, CD-ROM, WORM (recordable optical disc), MO (rewritable optical disc; magneto-optical disc), MD (mini disc), DVD (digital video disc), and the like. Other optical applications include light guide plates such as liquid crystal displays; optical films such as polarizing films, retardation films and light diffusing films; light diffusing plates; optical cards;

  Among these, it is suitable as an optical system lens or a laser scanning system lens constituting an optical pickup device that requires low birefringence, and is most suitable as an optical system lens of the optical pickup device.

  As an optical system lens of the optical pickup device, for example, an objective lens, an objective lens unit, a coupling lens (collimator), a beam expander, a beam shaper, a correction plate, and the like can be used.

The objective lens unit is a lens group formed by integrally combining a plurality of single lens optical lenses in the optical axis direction, and is used as at least one single lens optical lens among the plurality of single lens optical lenses. It is preferable to use a plastic optical element.
(Optical pickup device)
Next, the optical pickup device of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of the overall configuration of the optical pickup device, and FIG. 2 is a side view of a main part showing the structure of an objective lens.

  The optical pickup device 1 according to the present invention includes two types: a current DVD to which light having a wavelength of 650 nm is applied (hereinafter referred to as current DVD) and a so-called next-generation DVD to which light having a wavelength of 405 nm is applied (hereinafter referred to as next-generation DVD). The optical information recording medium 5 is a device for reproducing and recording information.

  The optical pickup device 1 of the present invention allows laser light (light) emitted from a laser oscillator (light source) 2 to pass through a collimator lens 3 and an objective lens (plastic optical element) 10 described later on the optical axis 4. Then, the light is collected on the information recording surface 6 of the optical information recording medium 5 to form a condensing spot, the reflected light from the information recording surface 6 is taken in by the deflecting beam splitter 7, and the beam spot is formed again on the light receiving surface of the detector 8. To do.

  The light source 2 includes a laser diode, and is configured to be able to select and emit light of two types of wavelengths of 650 nm and 405 nm by a known switching method.

  The objective lens 10 according to the present invention is created by molding the above resin composition by injection molding. As shown in FIG. 2, the objective lens 10 is a single lens having a double-sided aspheric surface, and is predetermined for a predetermined light beam passing through the optical surface 11 on one (light source side) optical surface 11. The optical path difference providing structure (fine structure) 20 for providing the optical path difference is provided.

  The optical path difference providing structure 20 includes three annular lens surfaces whose optical surfaces 11 are centered on the optical axis 4 (hereinafter, a first annular lens surface 21, a second annular lens surface 22, and a third annular zone in order from the inside). Of the three annular lens surfaces 21 to 23, the adjacent annular lens surfaces 21 to 23 have different refractive powers.

  The first annular lens surface 21 and the third annular lens surface 23 are on the same optical surface 11, and the second annular lens surface 22 is a surface translated from the optical surface 11. The first annular lens surface 21 transmits light having both wavelengths of 650 nm and 405 nm, the second annular lens surface 22 transmits light having a wavelength of 650 nm corresponding to the current DVD, and the third annular lens surface 23 The light of wavelength 405nm corresponding to next-generation DVD is allowed to pass through. The light that has passed through each of the annular lens surfaces 21 to 23 is collected at the same position on the information recording surface 6.

  In FIG. 2, the first annular lens surface 21 and the third annular lens surface 23 are provided on the same optical surface 11, but the first and third annular lens surfaces 21 and 23 are different from each other. The second annular lens surface 22 does not have to be provided on the same optical surface, and the second annular lens surface 22 is a surface translated from the optical surface 11, but it need not be a particularly translated surface. Further, the number of the three annular lens surfaces 21 to 23 may be five or at least three.

  Since the lens 10 is applied with the resin composition described above, when the lens 10 is melted and injected into a mold and molded, the first annular lens surface 21, the second annular lens surface 22, and the third lens surface of the mold are used. The resin has surely spread to the portion corresponding to the boundary portion of the annular lens surface 23. Therefore, the lens 10 is provided with the optical path difference providing structure 20 with high accuracy.

  By the action of the optical path difference providing structure 20 formed in this way, the lens 10 focuses the light emitted from the light source 2 on the information recording surface 6 with respect to a plurality of types of optical information recording media 5 such as the current DVD and the next generation DVD. Then, the light reflected from the information recording surface 6 toward the detector 8 can be condensed with high reliability.

  Further, since the resin composition contains an antioxidant, even when light of 405 nm for reproducing and recording information of the next generation DVD is transmitted, white turbidity and refractive index fluctuation hardly occur. Therefore, the optical pickup device 1 can be operated with high pickup characteristics over a long period of time.

  The objective lens 10 according to the present invention is not limited to the one having the optical path difference providing structure 20, and may be lenses 10 a to 10 e having structures 20 a to 20 d shown in FIGS. 3 to 7, for example.

  The optical path difference providing structure 20a in FIG. 3 includes a plurality of diffraction ring zones 21a with the optical axis 4 as the center, the plurality of diffraction ring zones 21a have a sawtooth cross section, and the optical surface of each diffraction ring zone 21a. 11a is a discontinuous surface. Further, the plurality of diffraction ring zones 21 a are formed so that the thickness increases as the distance from the optical axis 4 increases. The lens 10a shown in FIG. 3 is a so-called diffractive lens.

  The optical path difference providing structure 20b in FIG. 4 has a plurality of annular zone-shaped recesses 21b that cause a phase difference around the optical axis 4 in a concentric manner. The ring-shaped concave portions 21b are formed in five on one surface (upper and lower optical surfaces around the optical axis 4 in FIG. 4) of the optical surface 11b with the optical axis 4 as the center. Adjacent ring-shaped recesses 21b are continuously integrated with each other, and the entire cross-section of each ring-shaped recess 21b is stepped. Moreover, the optical surface 22b which forms each annular zone-shaped recessed part 21b is a surface translated with respect to the optical surface 11b. The lens 10b shown in FIG. 4 is a so-called phase difference lens.

  In FIG. 4, adjacent annular recesses 21 b are continuous and integrated, and the entire cross section is stepped. However, the annular recesses 21 b are simply provided on the optical surface 11 b individually. (In this case, for example, the lens 10 has the same structure as the lens 10 shown in FIG. 2). Also, in FIG. 4, the annular concave portion 21b is concentrically formed, but as shown in FIG. 5, the lens 10c having the convex portion 23b on the third annular lens surface 23 of FIG. Good (in FIG. 5, components similar to those in FIG. 2 are given the same reference numerals).

  The optical path difference providing structure 20d in FIG. 6 includes a plurality of diffraction ring zones 21d centered on the optical axis 4, the plurality of diffraction ring zones 21d have a sawtooth cross section, and the optical surface of each diffraction ring zone 21d. 11d is a discontinuous surface. The cross section of each diffraction ring zone 21d is a stepped shape of three steps 22d along the optical axis direction, and the optical surface 12d of each step 22d is a discontinuous surface and is a surface orthogonal to the optical axis 4. Yes.

  The lens 10d shown in FIG. 6 may have, for example, a hologram optical element (HOE) 10e having an optical path difference providing structure 20d similar to FIG. 6 and an objective lens 10f as shown in FIG. . In this case, the hologram optical element 10e uses a plate-like optical element, and the optical path difference providing structure 20d is provided on the surface of the objective lens 10f of the optical element. The optical pickup device 1 according to the present invention may reproduce and record information on three types of optical information recording media 5 such as a CD, a current DVD, and a next-generation DVD. The combination of the optical information recording medium 5 for reproducing and recording information by the optical pickup device 1 is a design matter and is set as appropriate.

  As described above, the plastic optical element of the present embodiment is an alicyclic hydrocarbon copolymer in which a chain unit having a hindered amine structure in the side chain is directly bonded in a polymer molecular chain or the alicyclic hydrocarbon. Since it is molded using a resin composition containing a copolymer, bleeding out of hindered amine sites having a light stabilizing function is suppressed, and the hindered amine is uniformly dispersed in the resin composition. Even if irradiation with light having a short wavelength such as a wavelength of 405 nm is continuously received, deterioration such as white turbidity and refractive index fluctuation of the optical element can be effectively suppressed. That is, the light stability of the optical element can be improved, and the characteristics can be maintained for a long time.

  Accordingly, for example, information can be read and written with good pickup characteristics over a long period of time on an optical information recording medium having a high information density such as a Blu-ray Disc, and the optical pickup device has high reliability. Can be obtained.

  In addition, by appropriately selecting various stabilizers from phenol-based stabilizers, hindered amine-based stabilizers, phosphorus-based stabilizers and sulfur-based stabilizers and adding them to the resin composition, the optical characteristics of the optical element to be molded can be improved. Variations can be suppressed more synergistically.

  Furthermore, since the melt index is in a range suitable for a molding method such as injection molding, the melted resin composition has an appropriate fluidity. For example, when an optical element is molded by injection molding or the like, it melted. The resin composition reaches the tip of the portion corresponding to the fine structure, and thus the optical element thus molded is provided with a predetermined fine structure formed with high accuracy.

  The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these.
(Production Example 1)
The inside of a stainless steel reactor equipped with a stirrer was sufficiently dried and purged with nitrogen, and then charged with 300 parts by mass of dehydrated cyclohexane, 60 parts by mass of styrene, and 0.38 parts by mass of dibutyl ether, while stirring at 60 ° C. The polymerization reaction was initiated by adding 0.36 parts by mass of an n-butyllithium solution (15% hexane solution). After performing the polymerization reaction for 1 hour, from the reaction solution, 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-piperidylmethacrylate. The mixed 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 Chemical Industry 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 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. After diluting by adding 800 parts by mass of cyclohexane, the reaction solution was poured into 3500 parts by mass of isopropanol to precipitate a copolymer. Next, this copolymer was collected by filtration and dried under reduced pressure at 80 ° C. for 48 hours to obtain Resin 1. Mw of the obtained copolymer was 86,400, Mw / Mn was 1.15, the hydrogenation rate of the main chain and the aromatic ring was 99.9%, and Tg was 127.2 ° C.
(Production Example 2)
In Production Example 1, copolymerization was carried out in the same manner except that 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate was added in an amount of 0.8 to 8 parts by mass. Resin 2 was obtained. Mw of the obtained copolymer was 84,400, Mw / Mn was 1.18, the hydrogenation rate of the main chain and the aromatic ring was 99.9%, and Tg was 126.8 ° C.
(Production Example 3)
Resin 3 was obtained by carrying out copolymerization in the same manner as in Production Example 1 except that 1,2,2,6,6-pentamethyl-4-piperidylmethacrylate was not added. Mw of the obtained copolymer was 87,200, Mw / Mn was 1.17, the hydrogenation rate of the main chain and the aromatic ring was 99.9%, and Tg was 127.8 ° C.

  With a composition ratio of 0.5 parts by mass of pentaerythritol distearate as a surfactant to 100 parts by mass of the resin 1 obtained in Production Example 1, a biaxial kneader (Toshiba Machine Co., Ltd., TEM-35B, screw (Diameter 37 mm, L / D = 32, screw rotation speed 150 rpm, resin temperature 240 ° C., feed rate 10 kg / hour), kneaded, and pelletized. The obtained pellets were dried at 70 ° C. for 2 hours using a hot air dryer in which air was circulated to remove moisture, and then the cylinder temperature was 280 ° C. and gold was injected by an injection molding machine (ATOSHOT MODEL 30A manufactured by FANUC). Injection molding was performed at a mold temperature of 80 ° C., a primary injection pressure of 98.1 MPa, and a secondary injection pressure of 78.4 MPa to obtain a resin substrate, a molded plate 1 having a diameter of 30 mm and a thickness of 3 mm.

  In Example 1, 1.0 part by mass of tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate is added as a hindered amine stabilizer during kneading. Except for this, the same operation was performed to obtain a molded plate 2.

In Example 1, instead of the resin 1, the same operation was performed except that 20 parts by mass of the resin 2 and 80 parts by mass of the resin 3 were mixed to obtain a molded plate 3.
(Comparative Example 1)
With a composition ratio of 0.5 parts by mass of pentaerythritol distearate as a surfactant to 100 parts by mass of the resin 3 obtained in Production Example 3, a biaxial kneader (Toshiba Machine Co., Ltd., TEM-35B, screw (Diameter 37 mm, L / D = 32, screw rotation speed 150 rpm, resin temperature 240 ° C., feed rate 10 kg / hour), kneaded, and pelletized. The obtained pellets were dried at 70 ° C. for 2 hours using a hot air dryer in which air was circulated to remove moisture, and then the cylinder temperature was 280 ° C. and gold was injected by an injection molding machine (ATOSHOT MODEL 30A manufactured by FANUC). Injection molding was performed at a mold temperature of 80 ° C., a primary injection pressure of 98.1 MPa, and a secondary injection pressure of 78.4 MPa to obtain a resin substrate, a molded plate 4 having a diameter of 30 mm and a thickness of 3 mm.
(Comparative Example 2)
In Comparative Example 1, 2.0 parts by mass of tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate is added as a hindered amine stabilizer during kneading. Except for the above, the same operation was performed to obtain a molded plate 5.
[Evaluation of resin molded plate]
About the shaping | molding plates 1-5 obtained in Examples 1-3 and Comparative Examples 1 and 2, fusion | melting characteristic and optical characteristic evaluation were implemented with the following method.
(Melt index measurement)
For each of the plastic optical elements (molded plates) 1 to 5, the melt index at a temperature of 260 ° C. and a load of 2.16 kg was measured according to the method defined in ASTM D1238.
(Evaluation of coloring and transparency of molded products)
About the said shaping | molding plates 1-5, the light transmittance by wavelength 400nm and the color tone through transmitted light were observed visually, and the coloring property and transparency were evaluated according to the following reference | standard.

  (Double-circle): Light transmittance is 90% or more, and coloring is not seen.

  ○: The light transmittance is 85% or more and less than 90%, and no coloring is observed.

  (Triangle | delta): Light transmittance is 85% or more and less than 90%, and very slight coloring is seen, but it exists in the range accept | permitted practically.

X: The light transmittance is less than 85%, coloring is observed, and there is a problem in practical use.
(Evaluation of light durability)
In a constant temperature and humidity chamber of 80 ° C. and 55% RH, a light spot having a wavelength of 405 nm is emitted from the laser diode of the light source 2 onto each molded plate 1 to 5 on each molded plate 1 to 5 with a circular spot having a diameter of 1 cm. After continuous irradiation as light for 250 hours, the laser irradiation spot was visually observed, and durability was evaluated according to the following criteria.

  A: After continuous irradiation, no alteration is observed in the laser irradiated portion.

  Δ: Slight turbidity is observed at the laser irradiation site after continuous irradiation, but it is in a practically acceptable range.

  X: After continuous irradiation, a white turbidity phenomenon is observed at the laser irradiation site, but there is a problem in practical use.

  Table 1 shows the results of evaluation of melting characteristics and optical characteristics for each of the molded plates 1 to 5.

  As shown in Table 1, the molded plate molded using the resin composition of the present invention does not cause coloring or clouding even when continuously irradiated with light having a short wavelength for a long time, and further maintains high transparency. I was able to.

  A plastic optical element (objective lens) having the same composition as that of the plastic optical element of the present invention described in Examples 1 to 3 and having the configuration described in FIGS. Each optical pickup device was fabricated with the structure described. Next, using each optical pickup device, recording and reproduction on a DVD were performed using light of a wavelength of 405 nm by a laser diode.

  As a result, all of the optical pickup devices using the plastic optical element of the present invention showed good pickup characteristics.

Claims (5)

The repeating unit (a) having an alicyclic structure represented by the following formula (1), and a chain structure represented by the following formula (2) and / or the following formula (3) and / or the following formula (4) A repeating unit (b) and a chain unit (c) having a hindered amine structure represented by the following formula (5) in the side chain,
An alicyclic structure in which the total content of the repeating unit (a) and the repeating unit (b) is 90% by weight or more, and the content of the repeating unit (b) is 1% by weight or more and less than 10% by weight. An optical element formed by using a hydrocarbon-based copolymer or a resin composition containing the alicyclic hydrocarbon-based copolymer.

[In Formula (1), X is an alicyclic hydrocarbon group, and in Formula (1), Formula (2), Formula (3) and Formula (4), R1 to R13 are each independently a hydrogen atom, 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, a cyano group, an amide group, an imide group, or a silyl group), and in formula (5), R14 to R19 each independently represents a hydrogen atom or an alkyl group, Y Represents an alkylene group having 1 to 10 carbon atoms or an ester bond. ]   The alicyclic hydrocarbon copolymer contains at least one stabilizer selected from a phenol stabilizer, a hindered amine stabilizer, a phosphorus stabilizer, and a sulfur stabilizer. The optical element according to claim 1, wherein: The melt index (MI) value of the alicyclic hydrocarbon copolymer or the resin composition measured under the conditions of a temperature of 260 ° C. and a load of 2.16 kg is 20 <MI (g / 10 minutes) <60. In range
3. The optical element according to claim 1, wherein a predetermined fine structure is provided on at least one optical surface. An optical pickup device for reproducing and / or recording information on an optical information recording medium,
A light source that emits light;
An optical element unit that irradiates the optical information recording medium with light emitted from the light source and / or collects light reflected by the optical information recording medium, and
The optical element unit is
The repeating unit (a) having an alicyclic structure represented by the following formula (1), and a chain structure represented by the following formula (2) and / or the following formula (3) and / or the following formula (4) Of the repeating unit (b) and a chain unit (c) having a hindered amine structure represented by the following formula (5) in the side chain, and the repeating unit (a) and the repeating unit (b) An alicyclic hydrocarbon copolymer having a total content of 90% by weight or more and a content of the repeating unit (b) of 1% by weight or more and less than 10% by weight or the alicyclic hydrocarbon system An optical pickup device comprising an optical element formed by using a resin composition containing a copolymer.

[In Formula (1), X is an alicyclic hydrocarbon group, and in Formula (1), Formula (2), Formula (3) and Formula (4), R1 to R13 are each independently a hydrogen atom, 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, a cyano group, an amide group, an imide group, or a silyl group), and in formula (5), R14 to R19 each independently represents a hydrogen atom or an alkyl group, Y Represents an alkylene group having 1 to 10 carbon atoms or an ester bond. ]   5. The optical pickup device according to claim 4, wherein the light source emits light having a wavelength of 390 to 420 [nm].

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