WO2008016000A1

WO2008016000A1 - Composite material and optical element

Info

Publication number: WO2008016000A1
Application number: PCT/JP2007/064870
Authority: WO
Inventors: Hiroaki Ando; Hideaki Wakamatsu
Original assignee: Konica Minolta Opto, Inc.
Priority date: 2006-08-04
Filing date: 2007-07-30
Publication date: 2008-02-07

Abstract

Provided is an optical element wherein transparency is improved and moisture absorptivity is lowered while suppressing linear expansion coefficient. An objective lens as the optical element is provided by molding a composite material. The composite material contains a compound having an adamantyl group in a resin.

Description

Specification

Composite material and optical element

Technical field

[0001] The present invention relates to a composite material suitably used as an optical element material and an optical element formed thereby.

Background art

[0002] At present, glass materials and resin materials are mainly used as materials constituting optical elements, and among them, resin materials are often used because they are inexpensive and have excellent moldability. . As a resin material applicable to optical elements, for example, a copolymer of cyclic olefin and α-olefin (see Patent Document 1) is known. However, since the resin material has a high coefficient of linear expansion, the refractive index is changed by temperature change. Fluctuating to obtain optical stability.

[0003] To solve this problem, a composite material in which an inorganic filler (fine particles) is mixed in a resin material can be expected to suppress the linear expansion coefficient and to stabilize the refractive index (Patent Document 2). See). In the technique disclosed in Patent Document 2, an organic-inorganic composite material using silica-based particles has been proposed in order to improve the high linear expansion coefficient, which is a drawback of resin materials. Silica alone has a relatively low refractive index, but using a composite material eliminates the disadvantages of silica, which has a low refractive index, and broadens the range of applications as an optical material.

Patent Document 1: JP 2002-105131 A

Patent Document 2: Japanese Patent Laid-Open No. 2005-146042

Disclosure of the invention

Problems to be solved by the invention

[0004] However, since the composite material has poor compatibility between the resin material and the inorganic filler and the inorganic filler is difficult to disperse in the resin material, the optical element itself is inferior in transparency (light transmittance is reduced). There is a problem with the intrinsic nature of. Improving the transparency by increasing the affinity of the inorganic filler for the resin material requires a surface treatment, which increases costs and completely overcomes the transparency problem even if the surface treatment is applied. It does not lead to. Furthermore, when an inorganic filler is mixed in the resin material, the moisture absorption rate increases and the installation environment It becomes difficult to stabilize the refractive index with respect to fluctuations in the range.

[0005] On the other hand, it is also possible to examine the stability of the refractive index by suppressing the linear expansion coefficient by using a composite material in which an organic filler such as fiber is mixed in a resin material. Although the composite material can achieve a certain level of transparency without surface treatment, increasing the organic filler content in an attempt to reduce the coefficient of linear expansion will not provide sufficient transparency as an optical element. Birefringence occurs even if a certain level of transparency is maintained. Furthermore, when an organic filler is mixed in the resin material, the moisture absorption rate is increased, and it is difficult to stabilize the refractive index against fluctuations in the installation environment, as in the case of mixing an inorganic filler.

[0006] An object of the present invention is to improve the transparency and reduce the moisture absorption rate while suppressing the linear expansion coefficient.

Means for solving the problem

[0007] In order to achieve the above object, the first aspect of the present invention provides:

It is a composite material containing a compound having an adamantyl group in the resin.

[0008] In the composite material,

The compound having an adamantyl group may be a compound having only an adamantane skeleton, a compound having an adamantane skeleton in the main chain, or a compound having an adamantane skeleton in the side chain. Also good.

[0009] In the composite material,

The resin is preferably a cycloolefin resin.

[0010] The second aspect of the present invention is:

An optical element molded using the composite material of the first form.

The invention's effect

[0011] According to the present invention, it is possible to provide a composite material and an optical element that can improve transparency and reduce moisture absorption while suppressing the coefficient of linear expansion (see Examples below).

Yes

Brief Description of Drawings

FIG. 1 is a schematic diagram showing an internal structure of an optical pickup device. Explanation of symbols

1 Optical pickup device

2 Semiconductor laser oscillator

3 Collimator

4 Beam splitter

5 1/4 wave plate

6 Aperture

7 Objective lens (optical element)

8 Sensor lens group

9 Sensor

10 Two-dimensional actuator

D Optical disc

D1 Protection board

D2 Information recording surface

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. However, the embodiment described below has various technically preferable limitations S for carrying out the present invention, and the scope of the invention is not limited to the following embodiment and illustrated examples. .

[0015] First, the composite material according to the present invention will be described.

[0016] The composite material contains (1) a resin and (2) a compound having an adamantyl group. Hereinafter, (1) a resin and (2) a compound having an adamantyl group will be described, respectively, followed by (3) a method for producing a composite material, (4) properties of the composite material, and (5) a method for producing an optical element. Each application example will be described.

(1) Resin

As the resin, a thermoplastic resin, a thermosetting resin, a photocurable resin, or the like can be applied. Although it is not particularly limited as long as it is a transparent resin generally used as an optical material, the resin is thermoplastic due to the workability as an optical element and the molding cycle time. An acrylic resin, a cyclic olefin resin, a polycarbonate resin, a polyester resin, a polyether resin, a polyamide resin, or a polyimide resin, which are preferable to be a hydrophobic resin, are particularly preferable from the viewpoint of low hygroscopicity. A resin is preferred. Further, depending on the purpose used for the composite material, a silicon resin is preferably used as the curable resin which may be a curable resin such as a thermosetting resin or a photocurable resin. For example, as the resin, the compounds described in JP-A-2003-73559 can be listed, and preferred compounds are shown in Table 1 below. Of these resins, those having a moisture absorption rate of 0.5% or less are preferred, and those having a moisture absorption rate of 0.2% or less are more preferred.

[table 1]

(2) Compound having adamantyl group

The compounds having an adamantyl group include (2.1) a compound consisting only of an adamantane skeleton, (2.2) a compound having an adamantane skeleton in the main chain, and (2.3) having an adamantane skeleton in the side chain. Compounds. (2.1) Compound consisting only of adamantane skeleton

As one compound consisting only of an adamantane skeleton, a “polyadamantane oligomer” of the following formula (1) can be mentioned.

[0019] As a synthesis method of the polyadamantane oligomer, as shown in the following formula (A), a McMurry coupling reaction using Ti (O) as a catalyst between carbonyl groups of adamantanone and adamantane 2, 6 dione is performed. Just do it.

[0020] [Chemical 1]

(1)

[0021] Other compounds comprising only an adamantane skeleton include “poly (1,3-adamantane)” in which rings are bonded between bridgehead carbons.

[0022] As a method for synthesizing the poly (1,3 adamantane), as shown in the upper part of the following formula (B), 3, 3 'jib mouth mode 1 of the following formula (2) using metallic sodium in xylene. The Wurtz coupling reaction between the bridgehead carbons of 1'-biadamantane may be performed.

[0023] Further, as a method for synthesizing the poly (1,3 adamantane), as shown in the lower part of the following formula (B), 1,3-dib mouth modamantane of the following formula (3) is used as a starting material, and jetyl ether 1,3-Dehydroadamantane of the following formula (4) may be synthesized by reaction with potassium sodium alloy in a mixed solvent of HMPA and HMPA, and the 1,3-dehydroadamantane may be heated at 160 ° C. [0024] [Chemical 2]

(3): (4)

[0025] Other compounds having only a skeleton include the following formula (5) into which a substituent is introduced.

3-Adamantane) ”.

In the following formula (5), “R, R ′” is preferably a linear, branched or cyclic alkyl group. “N” is an integer of 1 or more.

As a method for synthesizing poly (1,3-adamantane) of the following formula (5) into which a substituent is introduced, force-coupling polymerization can be applied. For example, as shown in the following formula (C), a novel monomer 3, 3 'in formula (6) below, 5'-dibutyl mouth 1, 5 '-dibutyl- 1, 1' biadamantane, 3, 3 'in formula (7) below, 5', jib mouth mode 5, 5 ', 7, 1'-Tetrabutyl-1, \ 'Viadamantane may be synthesized and coupling polymerization using sodium metal in n-octane may be performed.

[0028] [Chemical 3

ίδ)

(S) = C ₄ H ₉ , "= H

(?) R, R '= CH ₃

[0029]

Is also applicable.

In the following formula (8), “R” is preferably a linear, branched or cyclic alkyl group! / ′. “N” is an integer of 2 or more. [0031] As a method for synthesizing the poly (1,3-adamantane), a chain-opening polymerization of 3-conductors may be performed! / ,.

[0032] [Chemical 4]

(8)

[0033] Specific examples of the poly (1,3-adamantane) of the above formula (8) into which a substituent is introduced include poly (1,3, -adamantane) of the following formulas (9), (10), (11) Can be mentioned.

[0034] As a synthesis method of poly (1,3-adamantane) represented by the following formulas (9), (10), (11),

As shown in (D), an unsubstituted form of the following formula (9a), 5-butyl-1,3-dehydroadamantan of the following formula (10a), 5,7-dibutyl-1,3— of the following formula (11a) Dehydroadamantane was synthesized as a novel butyl-substituted monomer, and these compounds were radically polymerized using AIBN and BPO, thermally polymerized under solvent-free conditions, and Et OBF and trifluoromethane.

3 4

What is necessary is just to perform cationic polymerization by a sulfonic acid.

[0035] [Chemical 5]

'(D)

(9a) R, R'sH (9): R, R '= H

(1 1 a) R, '-C ₄ H ₉

[0036] (2.2) Compound having adamantane skeleton in main chain

Specific examples of the compound having an adamantane skeleton in the main chain include compounds of the following formulas (20) and (25).

In the following formula (20) (25), “n” is an integer of 1 or more.

[0038] As a method for synthesizing the compounds of the following formulas (20) and (25), an adamantane derivative may be synthesized as a main raw material. [0039] [Chemical 6]

[0040] Other specific examples of the compound having an adamantane skeleton in the main chain include the following formulas (26), (

The compound of 27) is mentioned.

In the following formulas (26) and (27), “n” is an integer of 1 or more.

[0042] As a method for synthesizing the compounds of the following formulas (26) and (27), Friedel-Crafts reaction of aromatic compounds such as adamantane bromide and toluene diazol proceeds regioselectively and quantitatively. Use the Friedel-Crafts alkylation reaction via /! Specifically, as shown in the following formula (E), as the alkyl halide component, 1, 3—jib mouth modamantane of the following formula (26a) or 3, 3′—jib mouth mode of the following formula (27a), 1 'Biada

Using Γ, the following formula (26b, 27b) (a, ω-diphenol chain number = 2, 6, 12) is used as the nucleophilic aromatic component, and aluminum chloride is used as a catalyst in 1,2-dichloroethane. What is necessary is just to superpose | polymerize.

[0043] [Chemical 7]

[2.3] (2.3) Compound having adamantane skeleton in side chain

The compound having an adamantane skeleton in the side chain is a compound (copolymer) of the following formula (30).

In the following formula (30), “R” is a unit constituting the main chain of the compound, and “n” is an integer of 1 or more.

[0046] [Chemical 8]

Side chain

(30)

In the above formula (30), examples of the compound corresponding to the “side chain” include compound forces S of the following formulas (3 ;!) to (40). As a polymerization method, any method such as ordinary radical polymerization or canyon polymerization may be used.

[0048] [Chemical 9]

(31) (32) (33) (34)

(35) (36) es?)

[0049] (3) Manufacturing method of composite material

The method for producing the composite material is to disperse the compound having an adamantyl group described in each item of “(2. 1 2. 3)” above in the resin! /.

[0050] In the dispersion step, the compound having an adamantyl group synthesized in the synthesis step and a resin (particularly a thermoplastic resin) are mixed, and the compound having an adamantyl group is dispersed in the resin. As a method for mixing the compound having an adamantyl group and the resin, it is preferable to use a melt-kneading method from the viewpoint of reducing the amount of volatile substances used.

[0051] When the melt kneading method is used in the dispersion step, the compound having an adamantyl group and the resin may be added and kneaded all at once, or may be divided and added in stages. Yo.

[0052] As a method of dividing addition, a method of adding one component in several times, a method of adding one component at a time and adding other components stepwise, or a combination of these is used. I can do it. The addition of the compound having an adamantyl group can be performed in a powder or agglomerated state. Force that can be added in a state where a compound having an adamantyl group is dispersed in a liquid. In this case, it is necessary to perform a devolatilization treatment after kneading, and the aggregated particles are previously formed into primary particles. It is preferable to add after being dispersed in. Also, when a compound having an adamantyl group and a resin are kneaded in advance, components other than the resin (thermoplastic resin) that have not been added in advance are added and further melt kneaded. You can knead them! /, And you can add them in stages and knead them! /. [0053] When the melt-kneading method is used in the dispersion step, one kind of gas selected from the inert gases nitrogen, helium, neon, argon, krypton, and xenon, or a mixture of two or more kinds of gases is used. It is preferable to perform mixing in an atmosphere. However, even general gases such as carbon dioxide, ethylene gas, and hydrogen gas are not reactive to the material to be kneaded! /, If mixed with the inert gas described above, the gas is used. Anyway!

[0054] When the melt-kneading method is used in the dispersion step, it is preferable to eliminate residual oxygen as much as possible in the reaction system in the melt-kneading apparatus. Specifically, in the reaction system The oxygen content is preferably 1% or less, and more preferably 0.2% or less. This is because the resin is deteriorated by the oxidation reaction with oxygen and coloration is likely to occur.

[0055] As an apparatus applicable to the melt kneading method, a closed kneading apparatus or a batch kneading apparatus such as a lab plast mill, a Brabender, a Banbury mixer, a kneader, and a roll can be cited. As an apparatus used for the melt kneading method, a continuous melt kneading apparatus such as a single screw extruder or a twin screw extruder can be used. When using a continuous melt-kneading apparatus such as an extruder, it is possible to add the components to be added step by step from the middle of the cylinder.

[0056] As the dispersion apparatus for the mixture, various dispersion treatment machines such as a bead mill disperser, an ultrasonic disperser, a high-speed stirring disperser, and a high-pressure disperser can be applied. it can. As the beads used in the bead mill disperser, force S, such as dinoreconia beads and glass beads, and zirconia beads are preferably used. Further, it is more preferable that the diameter of the beads to be used is smaller, and the preferred diameter is in the range of 0.001 to 0.1 mm.

[0057] In addition, various additives may be added alone or in combination as necessary in the composite material production process! /.

[0058] Examples of additives include antioxidants, light stabilizers, heat stabilizers, weather stabilizers, stabilizers such as ultraviolet absorbers and near infrared absorbers, resin modifiers such as lubricants and plasticizers, and soft polymers. And anti-clouding agents such as alcoholic compounds, coloring agents such as dyes and pigments, other antistatic agents, flame retardants and the like. [0059] Among these additives, examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, and phenolic antioxidants. By blending these antioxidants, it is possible to prevent the coloring and strength of the lens from being deteriorated due to oxidative deterioration during molding without reducing transparency and heat resistance.

[0060] Further, 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. However, it is preferably within a range of 0.00;! To 20 parts by mass with respect to 100 parts by mass of the composite material, more preferably within a range of 0.01 to 10 parts by mass.

[0061] As the phenolic antioxidant, conventionally known ones can be applied. For example, 2-tbutyl-6- (3-tbutyl-2-hydroxyl-5) described in JP-B-63-179953. (Methylbenzyl) 4 methylphenyl acrylate, 2, 4 di-tert-aminol-6- (1- (3,5 di-tert-aminol-2-hydroxyphenyl) ethynole) phenyl acrylate, etc. — Octadecinole 1- (3,5 di-tert-butyl-4-hydroxyphenyl) propionate and other acrylate compounds described in Japanese Patent No. 168643, and 2,2′-methylene bis (4-methyl-6-t-butylphenol) 1, 1, 3 Tris (2 methinore 4-hydroxy-1-5-butyl butylenole) butane, 1, 3, 5-trimethinore 2, 4, 6 tris (3,5-di-tert-butyl-4-hydroxybenzyl) ) Benzene, tetra Kiss (methylene 3- (3 ', 5'-di-butynol-monohydroxyphenylpropionate)) methane, ie pentaerythrmethyl-tetrakis (3- (3, 5-di-tert-butyl-4) -Hydroxyphenylpropionate)), triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl)

Alkyl-substituted phenolic compounds such as propionate), 6- (4-hydroxy-3,5-di-tert-butylanilino) -1,2,4 bisoctylthio-1,3,5 triazine, 4 bisoctylthio-1,3,5-triazine, Examples include 2-azine thiol 4,6-bis (3,5-di-t-butyl-4-oxyanilino) -triazine group-containing phenolic compounds such as 1,3,5-triazine.

[0062] The phosphorus antioxidant 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 (noyulpheninole) phosphite, tris (dinouylfeninore) phosphite, tris (2,4 di-t-butylphenolophosphite), 10— (3,5 di t-butyl-4-hydroxybenzyl) 9, 10 dihydro-9 oxa 10-phosphaphenanthrene 10-oxide and other monophosphite compounds, 4, A'-butylidenebis (3-methyl-6-t butylphenol tri Decyl phosphite), 4, A′-isopropylidene monobis (phenyl didialkyl (C 12 -C 15 phosphite)) and the like. Of these, tris (noyulphenyl) phosphite, tris (dinoylphenyl) phosphite, and tris (2,4 di-tert-butylphenyl) phosphite are particularly preferred.

[0063] Examples of iow antioxidants include dilauryl 3, 3 thiodipropionate, dimyristinole 3, 3'-thiodipropionate, distearyl 3, 3-thiodipropionate, lauryl stearyl 3, 3 —Chiodipropionate, pentaerythritol-tetrakis (/ 3 lauryl thiopropionate), 3, 9 bis (2 dodecylthioethyl) 2, 4, 8, 10—tetraoxaspiro [5, 5] undecane Etc.

[0064] Further, in addition to the above-mentioned phenol-based, phosphoric acid-based and xio-based antioxidants, amine-based antioxidants such as diphenylamine derivatives, nickel or zinc thiocarbamate, etc. can also be applied as antioxidants. It is.

[0065] Of the additives described above, a compound group having a minimum temperature at the glass transition temperature of 30 ° C or less may be blended as the cloudiness inhibitor. As a result, it is possible to prevent the occurrence of white turbidity in an environment of high temperature and high humidity for a long time by suppressing deterioration of various properties such as transparency, heat resistance and mechanical strength.

[0066] Among the above-mentioned additives, examples of the light-resistant stabilizer include benzophenone-based light-resistant stabilizer, benzotriazole-based light-resistant stabilizer, hindered amine-based light-resistant stabilizer, and the like. From the viewpoint of properties and the like, it is preferable to use a hindered amine light-resistant stabilizer (hereinafter referred to as “HALS”). As such HALS, those having a low molecular weight, medium molecular weight and high molecular weight can be appropriately selected. However, when producing molded products from composite materials, low molecular weight or medium molecular weight HALS may be used. Particularly when a film-like molded body is produced, it is preferable to use high molecular weight HALS.

[0067] HALS with a relatively small molecular weight includes LA-77 (Asahi Denka), Tinuvin765 (CSC), Tinuvinl23 (CSC), Tinuvin440 (CSC), Tinuvinl44 (CSC), HostavinN20 (Hoechst) Manufactured) and the like.

[0068] Examples of medium molecular weight HALS include LA-57 (Asahi Denka), LA-52 (Asahi Denka), LA-67 (Asahi Denka), LA-62 (Asahi Denka), and the like. It is done.

[0069] HALS with large molecular weights are LA-68 (Asahi Denka), LA-63 (Asahi Denka), Ho stavinN30 (Hoechst), Chimassorb944 (CSC), Chimassorb2020 (CSC), Chimassorbl l9 (CSC), Tinuvin622 (CSC), CyasorbUV-3346 (Cytec), CyasorbUV-3529 (Cytec), Uvasil299 (GLC), etc.

[0070] Further, it is also preferable to slightly combine various lubricants and fluorine elastomers as processing aids during molding and extrusion.

(4) Properties of composite materials

The light transmittance of the composite material produced as described above is preferably 50% or more, more preferably 70% or more, with respect to 405 nm light when the thickness is 3 mm. More preferably, it is 85% or more.

[0071] Regarding the Abbe number of the composite material, it is preferable to use particles capable of obtaining anomalous force dispersibility in which various values can be selected by selecting a compound having an adamantyl group or a resin. In this case, the composite material can be effectively used for achromatization, and its value may increase.

[0072] The water absorption rate of the composite material is preferably 2% or less, more preferably 1% or less in an environment of a temperature of 80 ° C and a relative humidity of 90%, more preferably 0.5%. It is most preferable that

[0073] In the present embodiment, the water absorption rate is expressed in mass% unless otherwise specified. In addition, the water absorption rate can be measured from a change in mass when a pre-dried composite material is stored for a certain period of time under specific high temperature and high humidity conditions. This embodiment In the method, the water content when dried is measured by the Karl Fischer method, and the mass change is measured after the subsequent water absorption, thereby calculating the water absorption rate more accurately.

[0074] The composite material is preferably negative in the AMES test! /. This is because a positive result in the AMES test may impair the user's health, increase the environmental burden, and reduce the material stability.

(5) Optical element manufacturing methods and application examples

(5.1) Optical element manufacturing method

By molding the composite material obtained as described above, it is possible to manufacture the optical element according to the present invention. The molding method is not particularly limited, but the melt molding method is preferable from the viewpoint of characteristics such as low birefringence, mechanical strength and dimensional accuracy in the molded product. Examples of the melt molding method include press molding, extrusion molding, and injection molding. From the viewpoint of productivity, it is preferable to apply injection molding as the melt molding method. In addition, in the case of forming a molded product with a photocurable resin, cast polymerization or the like can be used.

[0075] The molding condition is a force that is appropriately selected according to the purpose of use or molding method. For example, as the temperature of the composite material in injection molding, an appropriate fluidity is imparted to the resin at the time of molding to reduce the distortion of the molded product. It is preferable that the temperature is in the range of 150 ° C to 400 ° C from the viewpoints of preventing silver streaks due to thermal decomposition of the resin and effectively preventing yellowing of the molded product. More preferably, it is within the range of 200 ° C to 350 ° C, and particularly preferably within the range of 200 ° C to 330 ° C.

[0076] When injection molding is used as a molding method, all general methods such as a molding method using carbon dioxide gas as a plasticizer and a method of improving transferability by induction heating of a mold can be applied. is there.

[0077] The molded product 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 or a sheet shape, and has a low birefringence, Since it is excellent in transparency, mechanical strength, heat resistance, low water absorption, etc., it can be applied to various optical components.

(5.2) Application examples of optical elements

Examples of application of the optical element according to the present invention to an optical component include an optical lens and an optical prism. Specific examples of such lenses include: camera imaging lenses; microscopes, endoscopes, telescope lenses, and other lenses; spectacle lenses and other light-transmissive lenses; CD, CD-ROM, WORM (write-once optical discs) ), MO (rewritable optical disk; magneto-optical disk), MD (laser scanning system lens such as mini-debeam printer fΘ lens, sensor lens, etc .; prism lens of camera lens system).

Other optical applications include light guide plates such as liquid crystal displays; optical films such as polarizing films, retardation films, and light diffusion films; light diffusion plates; optical cards; liquid crystal display element substrates.

In addition, the optical element according to the present invention is also suitably used as various filters, gratings, optical fibers, flat optical waveguides, and the like.

[0080] Among the above-described molded products, the molded article is suitably used as an optical element such as a pickup lens requiring low birefringence or a laser scanning system lens.

Hereinafter, the optical pickup device 1 in which the optical element according to the present invention is used as the objective lens 7 will be described with reference to FIG.

FIG. 1 is a schematic diagram showing the internal structure of the optical pickup device 1.

As shown in FIG. 1, the optical pickup device 1 includes a semiconductor laser oscillator 2 as a light source. On the optical axis of the blue light emitted from the semiconductor laser oscillator 2, the direction force away from the semiconductor laser oscillator 2 is collimator 3, beam splitter 4, 1/4 wavelength plate 5, aperture 6, The objective lens 7 is sequentially arranged.

[0084] A sensor lens group 8 and a sensor 9 composed of two sets of lenses are sequentially disposed in a position close to the beam splitter 4 and in a direction perpendicular to the optical axis of the blue light described above.

[0085] The objective lens 7 as an optical element is disposed at a position facing the optical disc D, and collects the blue light emitted from the semiconductor laser oscillator 2 on one surface of the optical disc D. It is summer. Such an objective lens 7 is provided with a two-dimensional actuator 10, and the objective lens 7 is movable on the optical axis by the operation of the two-dimensional actuator 10.

Next, the operation of the optical pickup device 1 will be described. The optical pickup device 1 emits blue light from the semiconductor laser oscillator 2 at the time of recording information on the optical disc D or at the time of reproducing information recorded on the optical disc D. As shown in FIG. 1, the emitted blue light becomes a light beam L1, which is transmitted through the collimator 3 and collimated into infinite parallel light. Transparent. Further, after passing through the aperture 6 and the objective lens 7, a condensing spot is formed on the information recording surface D2 via the protective substrate D1 of the optical disc D.

[0088] The light that forms the focused spot is modulated by the information pits on the information recording surface D2 of the optical disc D and reflected by the information recording surface D2. Then, the reflected light becomes a light beam L 2, is sequentially transmitted through the objective lens 7 and the diaphragm 6, is changed in polarization direction by the quarter-wave plate 5, and is reflected by the beam splitter 4. After that, astigmatism is given through the sensor lens group 8 and received by the sensor 9, and finally converted into an electric signal by being photoelectrically converted by the sensor 9.

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.

Note that the numerical aperture NA required for the objective lens 7 varies depending on the thickness dimension of the protective substrate D1 and the size of the information pit in the optical disc D. In this embodiment, it is a high-density optical disc D, and its numerical aperture is set to 0.85.

Example

[0091] (1) Sample preparation

(1. 1) Preparation of compound 1 (compound consisting only of adamantane skeleton)

Polym. Prepr., Jpn., 49 (2), 150 (2000)

Polym. Prepr., Jpn., 49 (7), 1359 (2000)

Polym. Prepr., Jpn., 50 (2), 277 (2001)

Polym. Prepr., Jpn., 50 (7), 1270 (2001)

Polvm. Prepr., Jpn., 52 (7), 1422 (2003)

Based on the above literature, we synthesized 3, 3'-jib mouth mo 5, 5'-dicyclohexyl lu 1, 1-biadamantane. The synthesized product was subjected to a coupling reaction using metallic sodium in n-octane to obtain a polymer (polyadamantane). The polymer is referred to as “Compound 1”. did.

(1. 2) Preparation of compound 2 (inorganic particles)

Add 5g of Alumina (Daimei Chemicals TM-300) to 100g of ethanol.

(Manufactured by Kotobuki Giken Co., Ltd.) was dispersed with _0.05 mm beads at a peripheral speed of 6 m / _SeC for 30 minutes. 680 ml of ethanol and 230 ml of aqueous ammonia (28% Kanto Chemical) were added to the resulting slurry. While stirring the mixture, a mixed solution of 30 g of tetraethoxysilane (Shin-Etsu Chemical) in 200 ml of ethanol and 100 ml of water was added dropwise to the mixture over 6 hours. After completion of the dropwise addition, the mixture was stirred overnight. Alumina was separated from the mixture using a centrifuge, and the alumina was washed with ethanol. The washed alumina was dried at 90 ° C to remove ethanol, and then calcined at 450 ° C. When the obtained alumina particles were observed with a TEM, the particle diameter was about 10 nm. The alumina particles were referred to as “Compound 2”.

(1. 3) Preparation of compound 3 (compound having adamantane skeleton in the side chain)

A dropping device, a thermometer, a nitrogen gas introduction tube, a stirring device, and a reflux condenser were installed in a 4-liter 4-separable flask, and 20 g of benzene was charged into the flask and heated at about 80 ° C. 2- Mechinore 2 § Dammann Chino Leme Tatari rate 100 g, N, N ^f - Azobisuisoba Reronitoriru 2g, a solution was uniformly mixed with benzene 80 g, the flask 2 hours in force, only was added dropwise, at the same temperature For 5 hours. The obtained solution was dried to obtain a polymer. The polymer was designated as “Compound 3”.

(1. 4) Preparation of compound 4 (compound having an aromatic ring)

Syndiotactic polystyrene (Idemitsu Kosan Zalek S 100) was designated as “Compound 4”.

(1.5) Fabrication of composite materials;! ~ 5

Using a polylab system (manufactured by HAAKE), the above-mentioned compounds;! ~ 4 and cycloolefin resin (APEL5014 made by Mitsui Chemicals) were melt-kneaded at 200 ° C for 10 minutes. 4 ”. In the production of composite materials! ~ 4, the specific gravity of each compound;! ~ 4 is calculated from the volume of the kneaded material obtained from the sample weighed in advance, and each compound 1 ~ 4 is again 30 vol. A kneaded material was prepared so as to be%.

Cycloolefin resin (APEL5014 manufactured by Mitsui Chemicals) without kneading with the above compounds 1-4 As “Composite Material 5”.

(1.6) Preparation of sample;! ~ 5

The composite materials 1 to 5 were injection molded to obtain a molded sample for measurement (thickness 3 mm). These compacts were designated as “Samples !!-5”.

(2) Measurement of physical properties of samples 1-5

(2.1) Measurement of linear expansion coefficient

Using TMA / SS6100 made by SII Nanotechnology, sample in the range of 40-80 ° C; The thermal expansion of ˜5 was measured to determine the linear expansion coefficient. The results are shown in Table 2 below.

(2.2) Measurement of light transmittance

Using a spectrophotometer UV-3150 manufactured by Shimadzu Corporation, the transmittance for light with a wavelength of 587.5 mn was measured for each sample;! The measurement results are shown in Table 2 below.

(2.3) Measurement of moisture absorption rate

Use a high-temperature and high-humidity machine (Espec Co., Ltd. PR-2PK) to dry each sample; Stored for 500 hours. About each sample 1-5, the mass after drying for 100 hours and the mass after preserve | saving for 500 hours were measured, and the moisture absorption (%) was computed from the increase in the mass. The calculation results are shown in Table 2 below.

(2.4) Refractive index measurement

Using an automatic refractometer (KPR-200, manufactured by Carneu Optical Co., Ltd.), the refractive index at 23 ° C for light having a wavelength of 405 nm was measured for each of samples 1 to 5. The measurement results are shown in Table 2 below.

[Table 2]

(3) Summary

As shown in Table 2, comparing Samples 1 and 3 with Samples 2, 4 and 5, Samples 1 and 3 have the same linear expansion coefficient as Sample 2. Suppressed linear expansion compared to Samples 4 and 5 It has an effect and is excellent in terms of light transmittance, moisture absorption, and refractive index. From the above, it can be seen that it is useful to include a compound having an adamantyl group in the resin.

Claims

The scope of the claims

[1] A composite material containing a compound having an adamantyl group in a resin.

[2] The composite material according to [1], wherein the compound having an adamantyl group is a compound comprising only an adamantane skeleton.

[3] The composite material according to claim 1, wherein the compound having an adamantyl group is a compound having an adamantane skeleton in the main chain.

[4] The composite material according to [1], wherein the compound having an adamantyl group is a compound having an adamantane skeleton in a side chain.

[5] In composite materials,

The composite material according to any one of claims 1 to 4, wherein the resin is a cycloolefin resin.

[6] An optical element formed by using the composite material according to any one of claims 1 to 5.