JP2008280443A - Method for producing composite resin material, composite resin material, and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a thermally stable composite resin material excellent in light transmissivity and hydrophobicity by using microwaves; and an optical element using the composite resin material. <P>SOLUTION: This method for producing a composite resin material composed of at least a resin and an inorganic particle comprises the steps of coating the surface of an inorganic particle with a silane coupling agent and heat-treating the coated inorganic particle with microwaves in advance, and mixing and dispersing the surface-treated inorganic particle with a resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, etc., and particularly a method for producing a composite resin material that is thermally stable and excellent in hydrophobicity, and an optical element using the composite resin material About.

  Information devices such as a player, a recorder, and a drive for reading and recording information on an optical information recording medium (hereinafter also simply referred to 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 element of the medium. And an optical element such as a lens for condensing light.

  The optical element of the optical pickup device is preferably made of plastic as a material because it can be manufactured at low cost by means such as injection molding. As a plastic applicable to an optical element, a copolymer of a cyclic olefin and an α-olefin is known (for example, see Patent Document 1).

  By the way, for example, in the case of an information device capable of reading and writing information on a plurality of types of media such as a CD / DVD player, the optical pickup device has a configuration corresponding to the difference in the shape of both media and the wavelength of light to be applied. It is necessary to. In this case, it is preferable that the optical element unit is common to all the media from the viewpoint of cost and pickup characteristics.

  On the other hand, an optical element unit using plastic as a material is required to be a substance having optical stability such as a glass lens. For example, optical plastic materials such as cyclic olefins have significantly improved refractive index stability with respect to humidity, whereas the improvement in refractive index stability with respect to temperature is not yet sufficient.

  As one of methods for correcting the optical refractive index of the plastic lens as described above, various methods using a fine particle filler have been proposed. For example, there has been proposed a fine synthetic optical product which is composed of a polymer thermoplastic resin having temperature sensitivity and a dispersed fine particle substance and has reduced temperature sensitivity (see, for example, Patent Documents 2 and 3). ). However, a resin material obtained by mixing such existing oxide fine particles with a resin has a large decrease in light transmittance due to light scattering caused by fine particle aggregation, and provides a resin material that is not suitable for practical use as an optical element. I could only do it.

  Further, there has been proposed a high refractive index resin composition prepared by preparing composite inorganic particles and containing fine particles having a refractive index distribution and a transparent thermoplastic resin (see, for example, Patent Document 4). However, the aggregation of the fine particles cannot be prevented, and the light scattering caused by the difference in the refractive index between the inorganic fine particles and the resin and the difference in the refractive index inside the particle is large, so that sufficient transparency as an optical material cannot be obtained.

  In addition, when used in a pickup, an increase in environmental temperature due to an improvement in laser output is making the problem of heat resistance of the resin obvious. For this reason, attempts have been made to improve heat resistance by combining a resin with an inorganic substance, but when an inorganic material is usually combined with a thermoplastic resin, the inorganic material has a higher water absorption rate than the resin. Therefore, the moisture content of the composite material increases. As an influence of this, instability of temperature variation of spherical aberration often becomes a problem, and the composite materials that have been proposed so far have insufficient moisture hygroscopicity, and are not practical.

In particular, when an inorganic material is applied as an optical material, it is necessary to reduce the particle diameter to the nano-order, so that the surface area increases and the moisture hygroscopicity increases accordingly. Therefore, the surface hydrophobization treatment of the inorganic material is required, but since it is a fine particle, the conventional heat treatment cannot obtain the uniformity of the surface hydrophobization treatment. Thus, although not limited to optical materials, there are reports on heating and drying methods of microparticles using microwaves (see, for example, Patent Document 5).
JP 2002-105131 A JP 2002-207101 A Japanese Patent Laid-Open No. 2002-240901 JP-A-2005-213410 JP 2006-509704 A

  The present invention has been made in view of the above problems, and its purpose is suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, etc., and is particularly thermally stable and excellent in light transmission and hydrophobicity. An object of the present invention is to provide a method for producing a composite resin material using microwaves and an optical element using the composite resin material.

  The above object of the present invention is achieved by the following configurations.

  1. A method for producing a composite resin material comprising at least a resin and inorganic particles, the surface of the inorganic particles being coated with a silane coupling agent in advance and subjected to heat treatment with microwaves, and then the surface-treated inorganic material A method for producing a composite resin material, comprising mixing and dispersing particles with a resin.

  2. 2. The method for producing a composite resin material according to 1 above, wherein the inorganic particles are composite inorganic particles of silicon oxide and another metal oxide.

  3. 3. The method for producing a composite resin material according to 1 or 2, wherein the composite resin material has a water absorption rate of 0.2% by mass or less.

  4). A composite resin material produced by the method for producing a composite resin material according to any one of 1 to 3 above.

  5. 5. An optical element that is molded using the composite resin material described in 4 above.

  According to the production method of the present invention, it is suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, etc., and is thermally stable, hydrophobic and highly transparent to blue light, and a composite resin material using the same An optical element can be provided.

  Embodiments of the present invention will be described below. However, in the following embodiments, various technically preferable limitations for carrying out the present invention are given, but the scope of the invention is not limited to the following embodiments.

  First, a method for manufacturing an optical element according to the present invention will be described.

  The method for producing an optical element according to the present invention includes a step of forming inorganic particles, a step of surface treatment of inorganic particles, and a dispersion step of mixing and dispersing the surface-treated inorganic particles and resin to produce a composite resin material. And a step of molding the composite resin material.

(1) Resin In the present invention, a curable resin or a thermoplastic resin is used as the resin serving as a base material of the composite resin material.

  The curable resin used in the present invention can be cured by any of ultraviolet and electron beam irradiation or heat treatment, and is mixed with the thermoplastic resin in an uncured state and then cured. Any material can be used as long as it forms a transparent composite resin material, and an epoxy resin, a vinyl ester resin, a silicone resin, or the like is preferably used.

  For example, when an epoxy resin is used as the curable resin, any epoxy resin having at least two epoxy groups in one molecule can be used. Specifically, a bisphenol A type epoxy resin or a phenol novolac type can be used. Examples thereof include epoxy resins, halogenated epoxy resins such as o-cresol novolac type epoxy resins, triphenylmethane type epoxy resins, and bromine-containing epoxy resins, and epoxy resins having a naphthalene ring. The aromatic epoxy resin may be a hydrogenated epoxy resin in which an aromatic ring is hydrogenated to cyclohexane. These epoxy resins can be used individually by 1 type, or can also use 2 or more types together.

  Moreover, although it does not specifically limit as a hardening | curing agent of an epoxy resin, An acid anhydride hardening | curing agent, a phenol hardening agent, etc. can be illustrated. Specific examples of the acid anhydride curing agent include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride. Examples thereof include an acid, a mixture of 3-methyl-hexahydrophthalic anhydride and 4-methyl-hexahydrophthalic anhydride, tetrahydrophthalic anhydride, nadic anhydride, methyl nadic anhydride and the like.

  Moreover, a hardening accelerator is contained as needed. The curing accelerator is not particularly limited as long as it has good curability, is not colored, and does not impair the transparency of the curable resin. For example, 2-ethyl-4-methylimidazole (2E4MZ) Bicyclic amidines such as imidazoles, tertiary amines, quaternary ammonium salts, diazabicycloundecene and derivatives thereof, phosphines, phosphonium salts, etc. can be used. You may mix and use.

  As a method of curing the inorganic particle-containing resin material, after mixing and dispersing the inorganic particles in the resin, when the curable resin is an ultraviolet ray and an electron beam curable resin, a translucent mold having a predetermined shape is used. Filling the composite resin material and irradiating it with ultraviolet rays and electron beams to cure it, whereas when the curable resin is a thermosetting resin, it can be cured by compression molding, transfer molding, injection molding or the like. .

  Next, the thermoplastic resin will be described.

  The thermoplastic resin in which inorganic particles that can be used in the present invention are dispersed is not particularly limited as long as it is a transparent thermoplastic resin material that is generally used as an optical material. However, the processability as an optical element is considered. Then, an acrylic resin, a cyclic olefin resin, a polycarbonate resin, a polyester resin, a polyether resin, a polyamide resin, or a polyimide resin is preferable, and a cyclic olefin resin is particularly preferable. For example, JP 2003-73559 A, etc. The preferred compounds are shown in Table 1.

  Moreover, in the thermoplastic resin material which concerns on this invention, it is preferable that a water absorption is 0.2 mass% or less. Examples of the resin having a water absorption of 0.2% by mass or less include polyolefin resin (for example, polyethylene, polypropylene, etc.), fluororesin (for example, polytetrafluoroethylene, Teflon (registered trademark) AF (manufactured by DuPont), Top (made by Asahi Glass Co., Ltd.), cyclic olefin resin (for example, ZEONEX (manufactured by Nippon Zeon), Arton (manufactured by JSR), Apel (manufactured by Mitsui Chemicals), TOPAS (manufactured by Polyplastics), etc.), inden / Styrenic resins, polycarbonates and the like are suitable, but not limited to these. It is also preferable to use other resins compatible with these resins.

(2) Inorganic particles (2-1) Method for producing inorganic particles The inorganic particles used in the present invention may be particles having a single metal composition, or composite inorganic particles composed of silicon and one or more metal elements other than silicon. It may be. Examples of the composite inorganic particles include silica, which is silicon oxide, and titanium oxide, zinc oxide, aluminum oxide, zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, yttrium oxide. , Lanthanum oxide, cerium oxide, indium oxide, tin oxide, lead oxide and composite inorganic particles with one or more oxides.

  In the present invention, the composite inorganic particle may be a state in which silica and other metal elements in the particle are averagely distributed without being localized, and is a particle having no refractive index distribution in the particle. Alternatively, a two-layer structure having a silica layer on the surface of the metal oxide particles may be used.

  The shape of the inorganic particles that can be used in the present invention is not particularly limited, but spherical fine particles are preferably used. In addition, the particle size distribution is not particularly limited, but in order to achieve the effect of the present invention more efficiently, a material having a relatively narrow distribution than that having a wide distribution is preferably used. It is done.

  The composite inorganic particles can be produced by a pyrolysis method (a method in which raw materials are thermally decomposed to obtain fine particles, a spray drying method, a flame spray method, a plasma method, a gas phase reaction method, a freeze drying method, a heated kerosene method, a heated petroleum oil). Method), precipitation method (coprecipitation method), hydrolysis method (aqueous salt method, alkoxide method, sol-gel method), hydrothermal method (precipitation method, crystallization method, hydrothermal decomposition method, hydrothermal oxidation method), etc. It is done. Among these, the thermal decomposition method, the precipitation method, and the hydrolysis method are preferable methods from the viewpoint of producing a composite inorganic particle having a small particle size and uniform. Alternatively, it is also preferable to combine a plurality of these methods.

  The volume average particle size of the composite inorganic particles is preferably 1 nm or more and 50 nm or less. More preferably, it is 2 nm or more and 30 nm or less. When the thickness is 1 nm or less, it is difficult to uniformly disperse the resin. When the thickness is 50 nm or more, the light transmittance is reduced.

(2-2) Surface treatment process by microwave In this invention, the inorganic particle which concerns on this invention is surface-treated. In the present invention, surface treatment with a silane coupling agent is used as a method for surface treatment of inorganic particles.

  Specific examples of the silane coupling agent include vinylsilazane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, and hexamethyldisilazane. Silane, dimethyldimethoxysilane, methyltrimethoxysilane, hexamethyldisilazane and the like are preferably used.

  These surface treatment agents may be used alone or in combination, and the properties of the surface treatment fine particles obtained by the surface treatment agent used may differ, and the resin used to obtain the composite resin material It is also possible to achieve the affinity by selecting a surface treatment agent. The proportion of the surface treatment is not particularly limited, but the proportion of the surface treatment agent is preferably 10 to 99% by mass, and preferably 30 to 98% by mass with respect to the inorganic particles after the surface treatment. More preferred.

  Further, after the surface treatment of the composite inorganic particles with tetramethoxysilane or tetraethoxysilane, the surface treatment may be performed. Further, these treatment agents may be appropriately diluted with hexane, toluene, methanol, ethanol, acetone water or the like.

  As a surface treatment method using a surface treatment agent, heat treatment using microwaves is performed. By irradiating the particles with microwaves, the moisture adsorbed on the particle surface is selectively heated, the hydrolysis reaction of the silane coupling agent progresses dramatically, and the surface has high hydrophobicity in a short time. Processing can be performed.

  Microwaves are electromagnetic waves having various frequencies. Normal frequencies are 915 MHz and 2.45 GHz. During microwave processing, heat is generated by direct conversion from electromagnetic energy to molecular kinetic energy. The conversion from electromagnetic energy to thermal energy occurs based on the electromagnetic properties of the material to be heated.

  Whether it can be heated and dried with a microwave and to what extent it can be heated and dried with a microwave depends on its molecular structure. Polar molecules, such as water, can be well heated by microwaves. Microwaves can penetrate deeply depending on the material and heat over their entire volume. This is advantageous over normal heating and drying, in which heat penetrates only the material surface in the object.

  In addition, by applying microwave heat treatment to the water present inside the inorganic particles, the water inside the particles can be selectively heated in a short time without being absorbed by the particles themselves, and the internal adsorbed water can be efficiently used. Thus, it can be removed out of the particle system. For this reason, the composite resin material made from the particles does not cause aggregation such as that caused by long-time processing in an external heating type heater represented by an oven. It is done.

  Hydrophobic treatment of particle surface and removal of adsorbed water inside the particle can be performed in a short time in parallel. Deterioration of surface treatment agent due to long-time heat treatment, which is a problem in conventional methods (external heating, drying), residual internal The characteristic deterioration of the composite resin material due to adsorbed water can be solved.

(3) Dispersing step In the present invention, a manufacturing method for producing a composite resin material by adding, mixing, and dispersing inorganic particles to a molten resin, or mixing a resin dissolved in a solvent with inorganic particles. Then, a method for producing a composite resin material in which the organic solvent is removed thereafter is a preferred embodiment.

  In the present invention, the composite resin material is particularly preferably produced by a melt kneading method. For example, it is possible to polymerize a thermoplastic resin in the presence of inorganic particles, or to produce inorganic particles in the presence of a thermoplastic resin, but special conditions are required for resin polymerization and preparation of inorganic particles. Because it becomes. In the melt-kneading method, since a composite material can be produced by mixing a resin or inorganic particles produced by an existing method, it is usually possible to produce an inexpensive composite resin material.

  An organic solvent can be used in the melt-kneading. The use of the organic solvent can lower the temperature of the melt-kneading and can easily suppress the deterioration of the resin. In that case, it is preferable to deaerate after melt-kneading to remove the organic solvent from the composite resin material.

  Examples of the apparatus that can be used for melt kneading include a closed kneading apparatus such as a lab plast mill, a Brabender, a Banbury mixer, a kneader, a roll, and the like, or a batch kneading apparatus. Moreover, it can also manufacture using a continuous melt-kneading apparatus like a single screw extruder, a twin screw extruder, etc.

  In the method for producing a composite resin material of the present invention, when melt kneading is used, the resin and inorganic particles may be added and kneaded in one batch, or may be divided and added in stages. In this case, in a 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.

  However, when the resin is heated by melt kneading, it is preferable to first add a material that prevents thermal degradation of the resin, such as an antioxidant. Thereafter, when inorganic particles are added, the temperature of melt-kneading often increases, and the deterioration of the resin becomes remarkable without an antioxidant. On the other hand, the light-resistant stabilizer is often colored due to thermal degradation. Therefore, it is preferable to add in the subsequent step as much as possible in the melt kneading process. Therefore, at least a part is added after the addition of inorganic particles.

  In the present invention, when compounding by melt kneading is performed, the inorganic particles can be added in a powder or aggregated state. Or it is also possible to add in the state disperse | distributed in the liquid. When adding in the state disperse | distributed in the liquid, it is preferable to deaerate after kneading | mixing.

  When adding in the state disperse | distributed in a liquid, it is preferable to disperse | distribute agglomerated particles to a primary particle previously and to add. Various dispersing machines can be used for dispersion, but a bead mill is particularly preferable. There are various kinds of beads, but those having a small size are preferable, and those having a diameter of 0.1 mm or less and 0.001 mm or more are particularly preferable.

  The inorganic particles are preferably added in a surface-treated state, but there is a method such as an integral blend in which a surface treatment agent and inorganic particles are added simultaneously to form a composite with a resin, and any method is used. It is also possible.

(4) Molding process Although it does not specifically limit as a shaping | molding method, From a viewpoint of characteristics, such as the low birefringence in a molding, mechanical strength, and a dimensional accuracy, a melt molding method is preferable. Examples of the melt molding method include press molding, extrusion molding, and injection molding, and injection molding is preferable from the viewpoint of productivity. In the case of a photocurable resin, cast polymerization or the like can be used.

  The molding conditions are appropriately selected according to the purpose of use or molding method. For example, as the temperature of the composite resin material in the injection molding, an appropriate fluidity is imparted to the resin at the time of molding, so From the viewpoint of preventing silver streak due to thermal decomposition of the resin, and effectively preventing yellowing of the molded product, it is preferably in the range of 150 to 400 ° C, and in the range of 200 to 350 ° C. It is more preferable that it is in the range of 200 to 330 ° C.

  In injection molding, 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.

(4-1) Additive (4-1-1) Plasticizer As additives, stabilizers such as antioxidants, light stabilizers, heat stabilizers, weather stabilizers, ultraviolet absorbers and near infrared absorbers, Examples thereof include resin improvers such as lubricants and plasticizers, anti-clouding agents such as soft polymers and alcoholic compounds, colorants such as dyes and pigments, and other antistatic agents and flame retardants. They may be used alone or in combination.

  Among the additives, examples of the antioxidant include a phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant. By blending these antioxidants, it is possible to prevent lens coloring and strength reduction due to oxidative degradation during molding without lowering transparency, heat resistance and the like.

  The antioxidants can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range that does not impair the object of the present invention. The amount is preferably in the range of 0.001 to 20 parts by mass, more preferably in the range of 0.01 to 10 parts by mass with respect to parts.

(4-1-2) Cloudiness inhibitor As the cloudiness inhibitor, a compound having the lowest glass transition temperature of 30 ° C or lower can be blended. Thereby, it is possible to prevent white turbidity of the thin film in a high-temperature and high-humidity environment for a long time without deteriorating various characteristics such as transmittance, heat resistance, and mechanical strength.

(4-1-3) Antioxidant Here, conventionally known phenolic antioxidants are applicable. For example, 2-t-butyl-6 described in JP-A No. 63-179953 -(3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6- (1- (3,5-di-t-amyl- Acrylate compounds such as 2-hydroxyphenyl) ethyl) phenyl acrylate and the like, and octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate described in JP-A-1-168463, 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,3 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 Alkyl substituted phenolic compounds such as -butyl-4-hydroxy-5-methylphenyl) propionate) and 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-o Shianirino) triazine group-containing phenol compounds such as 1,3,5-triazine.

  The phosphorus antioxidant is not particularly limited as long as it is usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (Nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) Monophosphite compounds such as -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-di -Tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C1 -C15) phosphite) diphosphite compounds such as and the like. 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.

  Furthermore, as the sulfur-based antioxidant, for example, dilauryl-3,3-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3-thiodipropionate, laurylstearyl- 3,3-thiodipropionate, pentaerythritol-tetrakis (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5 5] and undecane.

  Furthermore, in addition to the above-mentioned phenolic, phosphoric acid and sulfur antioxidants, amine antioxidants such as diphenylamine derivatives, nickel or zinc thiocarbamates, etc. can also be applied as antioxidants.

(4-1-4) Light-resistant stabilizer The light-resistant stabilizer used for this invention is demonstrated. Although the light-resistant stabilizer is also called a light stabilizer, it is described as a light-resistant stabilizer in the present invention. Light stabilizers are broadly divided into quenchers and radical scavengers. Benzophenone light stabilizers, benzotriazole light stabilizers, and triazine light stabilizers are classified as quenchers, and hindered amine light stabilizers are classified as radical scavengers.

  In the present invention, it is preferable to use a hindered amine light-resistant stabilizer (HALS) from the viewpoint of transparency of the lens, color resistance, and the like. Specific examples of such HALS can be selected from low molecular weight to medium molecular weight and high molecular weight.

  For example, among LA-77 (Asahi Denka), Tinvin 765 (CSC), Tinuvin 123 (CSC), Tinuvin 440 (CSC), Tinvin 144 (CSC), Hostavin N20 (Hoechst) As molecular weights of the order, LA-57 (Asahi Denka), LA-52 (Asahi Denka), LA-67 (Asahi Denka), LA-62 (Asahi Denka), 68 (manufactured by Asahi Denka), LA-63 (manufactured by Asahi Denka), Hostavin N30 (manufactured by Hoechst), Chimassorb 944 (manufactured by CSC), Chimassorb 2020 (manufactured by CSC), Chimassorb119 (manufactured by CSC), Tinuvin 622 (manufactured by CSC), Cubor 626 (as manufactured by CSC), Cb (Cyt Ltd. c), manufactured by CyasorbUV-3529 (Cytec), and the like Uvasil299 (manufactured by GLC).

  In particular, it is preferable to use low and medium molecular weight HALS for the molded body and high molecular weight HALS for the film-like composite material. HALS is also preferably used in combination with a benzotriazole-based light-resistant stabilizer. Examples thereof include ADK STAB LA-32, LA-36, LA-31 (manufactured by Asahi Denka Kogyo), Tinuvin 326, Tinuvin 571, Tinuvin 234, Tinuvin 1130 (manufactured by CSC) and the like.

  Moreover, it is preferable that HALS is used together with the above-mentioned various antioxidants. The combination of HALS and the antioxidant is not particularly limited, and a combination of phenol, phosphorus, sulfur and the like is possible, but a combination of phosphorus and phenol is particularly preferable.

(4-1-5) Other Additives Various additives can be added as necessary during the preparation of the composite resin material according to the present invention and in the molding step of the composite resin material. Although there is no special limitation about additives, in addition to the antioxidants and light stabilizers described above, stabilizers such as heat stabilizers, weather stabilizers, near infrared absorbers; resin modifiers such as lubricants and plasticizers; Examples thereof include white turbidity preventive agents such as soft polymers and alcoholic compounds; colorants such as dyes and pigments; antistatic agents and flame retardants. These compounding agents can be used alone or in combination of two or more, and the compounding amount is appropriately selected within a range not impairing the effects described in the present invention.

(5) Optical element [Optical properties]
In the present invention, the light transmittance at a wavelength of 405 nm is preferably 70% or more at a thickness of 3 mm. This is because if it is less than 70%, the data reading accuracy is lowered. Many inorganic particles do not absorb 405 nm light, but the resin may absorb a little. In such a case, it is expected that the light transmittance at 405 nm is increased as a composite resin material by increasing the fraction of inorganic particles.

(5-1) Method for Producing Optical Element (Optical Lens) Next, a method for producing an optical resin lens, which is one of the optical elements produced from the composite resin material according to the present invention described above, will be described.

  The optical resin lens according to the present invention includes a step of first preparing a composite resin material and then molding the obtained composite resin material.

  The molded product of the thermoplastic resin material according to the present invention is obtained by molding a molding material made of the composite resin material. Although there is no particular limitation on the molding method, melt molding is preferable in order to obtain a molded product excellent in characteristics such as low birefringence, mechanical strength, and dimensional accuracy. Examples of the melt molding method include commercially available press molding, commercially available extrusion molding, and commercially available injection molding, and injection molding is preferred from the viewpoints of moldability and productivity.

  Molding conditions are appropriately selected depending on the purpose of use or molding method.For example, the temperature of the composite resin material in injection molding prevents the sink and distortion of the molded product by imparting appropriate fluidity to the resin during molding, From the viewpoint of preventing the occurrence of silver streak due to the thermal decomposition of the resin and further effectively preventing the yellowing of the molded product, the range of 150 to 400 ° C is preferable, the range of 200 to 350 ° C is more preferable, and the range is particularly preferable. Is in the range of 200-330 ° C.

  In injection molding, a molding method using carbon dioxide as a plasticizer can be used to improve fluidity. In addition, a technique for improving transferability by induction heating of the mold surface is also applicable.

  The composite resin material of the present invention is preferably negative for the AMES test. If the AMES test is positive, not only may the health of the user be impaired, but it may also have an environmental impact. Furthermore, it is unstable as a material, and there is a possibility that necessary stability may not be obtained.

  The molded product 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 or a sheet shape, and has a low birefringence and transparency. Since it is excellent in mechanical strength, heat resistance and low water absorption, it is used as an optical resin lens which is one of the optical elements of the present invention, but is also suitable as other optical components.

(5-2) Optical Lens The optical lens according to the present invention can be obtained by the above-described production method. Specific examples of application to optical components are as follows.

  For example, as an optical lens or an optical prism, an imaging system lens of a camera; a lens such as a microscope, an endoscope or a telescope lens; an all-light transmission lens such as a spectacle lens; a CD, a CD-ROM, or a WORM (recordable optical disk) , MO (rewritable optical disc; magneto-optical disc), MD (mini disc), optical disc pickup lens such as DVD (digital video disc), laser scanning system lens such as laser beam printer fθ lens, sensor lens; Examples include a camera viewfinder prism lens.

  Examples of optical disk applications include CD, CD-ROM, WORM (recordable optical disk), MO (rewritable optical disk; magneto-optical disk), MD (mini disk), DVD (digital video disk), 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 diffusion films; light diffusion plates; optical cards; liquid crystal display element substrates.

  Among these, it is suitable as a pickup lens or a laser scanning system lens that requires low birefringence, and is most suitably used for a pickup lens.

  As an example of the use of the optical resin lens according to the present invention, it is used as an objective lens used in a pickup device for an optical disk. In this embodiment, the target is a “high-density optical disk” using a so-called blue-violet laser light source having a used wavelength of 405 nm. This optical disk has a protective substrate thickness of 0.1 mm and a storage capacity of about 30 GB.

  In addition, on the surface of a molded product made from the composite resin material of the present invention, an inorganic compound, an organic silicon compound such as a silane coupling agent, an acrylic resin, a vinyl resin, a melamine resin, an epoxy resin, a fluorine resin, a silicone A hard coat layer made of a resin or the like can be formed. Examples of the means for forming the hard coat layer include known methods such as thermosetting, ultraviolet curing, vacuum deposition, sputtering, and ion plating. Thereby, the heat resistance, optical properties, chemical resistance, abrasion resistance, water resistance, etc. of the molded product can be improved.

  The invention is further illustrated by the following examples without however being limited thereto.

Example 1
[Formation of SiO ₂ / ZrO ₂ (SiO ₂ mole fraction 80%) based composite resin material]
A mixed liquid of 463.1 g of pure water, 104.8 g of 26% ammonia water and 4255.0 g of methanol, a mixed liquid of 3648 g of tetramethoxysilane (TMOS) and 229.4 g of methanol, and 643.2 g of pure water and 26% ammonia water 104.8 g of the mixed solution was dropped over 150 minutes while maintaining the liquid temperature at 25 ° C., and then a mixed solution of 5969 g of zirconium tetraisopropoxide and 150 g of isopropanol was added over 100 minutes to obtain a silica / zirconia mixed sol. It was.

  When the sol was distilled under heating under normal pressure, pure water was added dropwise while maintaining a constant volume, and when it was confirmed that the tower top temperature reached 100 ° C. and the pH was 8 or less, pure water was added dropwise. And a fine particle dispersion was obtained.

  Further, 15.4 g of methyltrimethoxysilane was added as a silane coupling agent, and the mixture was stirred at room temperature for 1 hour and then refluxed for 2 hours. Thereafter, while distilling with heating under normal pressure, methyl ethyl ketone was dropped while keeping the volume constant, and when the top temperature reached 79 ° C. and the water content was 1.0% or less, the process was terminated. After cooling to room temperature, microfiltration was performed using a 3 μ membrane filter to obtain a methyl ethyl ketone dispersion sol.

  Next, centrifugal separation, desalting, and elementary drying treatment were performed to obtain inorganic particle powder.

  Then, it heated at 200 degreeC with the microwave heating apparatus for 30 minutes (maximum output: 6kW / 2450MHz), and obtained the surface-treated silica / zirconia composite inorganic particle. As a result of TEM observation, the average particle diameter in terms of volume was 10 nm.

The composite inorganic particles and the resin were melt-kneaded while degassing to prepare a composite resin material. The content of inorganic particles in the composite resin material was set to 20% by volume with respect to the resin. At the time of melt kneading, the surface treatment of inorganic particles was performed by appropriately adding a surface treatment agent. The melt kneading was carried out under nitrogen using a lab plast mill KF-6V. The mixture was kneaded at 100 rpm for 10 minutes, and degassed under reduced pressure at 2.67 × 10 ³ Pa for 2 minutes before the end. The resin used was APL (cycloolefin resin APEL5014 (Mitsui Chemicals)).

Example 2
[Formation of SiO ₂ / Al ₂ O ₃ (SiO ₂ mole fraction 80%) based composite resin material]
A solution is prepared by adding 50 ml of pure water, 390 ml of ethanol, and 22 ml of ammonia to 7.2 g of Al ₂ O ₃ (primary particle diameter 13 nm). Next, 0.72 g of tetraethoxysilane (TEOS) is added and particle dispersion is performed for 1 hour. Further, 0.72 g of TEOS is added and the dispersion is advanced for 1 hour. Thus, a slurry solution obtained was obtained.

  To the prepared slurry, 18.16 g of TEOS is diluted with a mixed solution of ethanol and pure water, slowly dropped, and stirred at room temperature for 20 hours. Further, the particles are separated from the slurry using a centrifuge.

  The particles are dried under reduced pressure at 80 ° C. for 24 hours, and 10% by mass of hexamethyldisilazane as a silane coupling agent is further added to the particles, followed by heating with stirring. After cooling to room temperature, centrifugal separation and elementary drying treatment were performed to obtain inorganic particle powder.

  Then, it heated for 30 minutes at 200 degreeC with the microwave heating apparatus (maximum output: 6kW / 2450MHz), and obtained the surface-treated silica / alumina composite inorganic particle. As a result of TEM observation, the average particle diameter in terms of volume was 10 nm.

The composite inorganic particles and the resin were melt-kneaded while degassing to prepare a composite resin material. The content of inorganic particles in the composite resin material was set to 20% by volume with respect to the resin. At the time of melt kneading, the surface treatment of inorganic particles was performed by appropriately adding a surface treatment agent. The melt kneading was carried out under nitrogen using a lab plast mill KF-6V. The mixture was kneaded at 100 rpm for 10 minutes, and degassed under reduced pressure at 2.67 × 10 ³ Pa for 2 minutes before the end. The resin used was APL (cycloolefin resin APEL5014 (Mitsui Chemicals)).

Example 3
[Formation of SiO ₂ particle composite resin material]
A composite resin material was prepared in the same manner as in Example 1 except that the silica / zirconia composite inorganic particles were changed to silica.

Comparative Example 1: Heat treatment using an electric furnace In Example 2, the composite resin material was treated in the same manner except that the treatment by the microwave heating apparatus was changed to an open electric furnace and the treatment was performed at 200 ° C for 1 hour. Produced.

Comparative Example 2: No surface treatment A composite resin material was produced in the same manner as in Example 2, except that hexamethyldisilazane was not used.

Comparative Example 3: No heat treatment A composite resin material was prepared in the same manner as in Example 2, except that the heat treatment was not performed by microwaves.

Comparative Example 4: Surface treatment agent other than silane coupling A composite resin material was prepared in the same manner as in Example 2, except that 220 g of an aqueous ammonium stearate solution (10%) was used instead of hexamethyldisilazane. .

[Evaluation]
(Hydrophobicity)
The degree of hydrophobicity in the present invention is determined by adding 0.2 g of powder to 50 ml of water, adding methanol from the burette until the total amount of the powder is suspended, and adding the volume of methanol to ml. Obtained from Hydrophobicity = V / (50 + V).

  When powder was kneaded with the above optical resin, the kneaded resin was cloudy when the hydrophobicity was 50 or less, and it could not be used as an optical resin. This is considered due to separation of the interface between the particles and the resin.

(Light transmittance)
About each molding, the transmittance | permeability in wavelength 405nm was measured. The transmittance measurement method was in accordance with ASTM D1003. Light irradiation was performed by irradiating light with a wavelength of 405 nm and an intensity of 150 mW / cm ² for 1000 hours.

(Heat-resistant)
The temperature increase from room temperature to 100 ° C. and the reverse temperature decrease were repeated 100 cycles, and the presence or absence of distortion was visually evaluated.

○: There is no change in the resin by visual observation. Δ: There is a slight change in the change in the resin by visual inspection. X: The coloring of the resin is confirmed by visual inspection.

(Water absorption rate)
Using a high-temperature and high-humidity machine “PR-2PK” (product name, manufactured by Espec Co., Ltd.), the composite resin material previously dried at 100 ° C. and 10% RH for 100 hours is stored at 80 ° C. and 90% RH for 500 hours. The water absorption was determined from the increase in mass before and after. The amount of water absorption during drying was measured by dissolving the composite resin material in cyclohexane, and then measuring the composite resin material with a dry organic solvent by the Karl Fischer method.

  From Table 2, it can be seen that the composite resin material of the present invention is superior in heat resistance and light transmittance to the comparative composite resin material, has a small water absorption, and is excellent in hydrophobicity.

Claims (5)

A method for producing a composite resin material comprising at least a resin and inorganic particles, the surface of the inorganic particles being coated with a silane coupling agent in advance and subjected to heat treatment with microwaves, and then the surface-treated inorganic material A method for producing a composite resin material, comprising mixing and dispersing particles with a resin. The method for producing a composite resin material according to claim 1, wherein the inorganic particles are composite inorganic particles of silicon oxide and another metal oxide. The method for producing a composite resin material according to claim 1 or 2, wherein the composite resin material has a water absorption rate of 0.2% by mass or less. It manufactures with the manufacturing method of the composite resin material of any one of Claims 1-3, The composite resin material characterized by the above-mentioned. An optical element formed by using the composite resin material according to claim 4.