JP2009013009A - Method for producing inorganic fine particle powder, organic-inorganic composite material and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an inorganic fine particle powder which causes little expansion and agglomeration at manufacture of an organic-inorganic composite material, the organic-inorganic composite material manufactured using the inorganic fine particle powder, and an optical element excellent in optical properties, transparency and thermal stability. <P>SOLUTION: The method for producing the inorganic fine particle powder comprises the steps of: mixing a polymeric material with an inorganic fine particle containing a SiO<SB>2</SB>layer at least at its surface, provided that at least 80 mass% of the polymeric material is not thermally decomposed when heated to 300°C at a heating rate of 10°C/min in the atmosphere; drying the mixture; and firing the mixture to produce the inorganic fine particle powder. The organic-inorganic composite material and the optical element are manufactured using the inorganic fine particle powder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic-inorganic composite material containing inorganic fine particles formed of an oxide, a hydroxide or an oxide hydroxide, and an optical element using the same.

  Information equipment 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 “medium”) such as MO, CD, and DVD is provided with an optical pickup device. Yes. 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. An optical element such as a lens for condensing light by the light receiving element is included.

  The optical element applied to the optical pickup device is preferably made of plastic as a material from the viewpoint that it can be manufactured at a lower cost by means such as injection molding. As plastics applicable to optical elements, copolymers of cyclic olefins and α-olefins are known.

  An optical element unit using plastic as a material is required to have a characteristic having optical stability like a glass lens. For example, optical plastic materials such as cyclic olefins have an extremely low water absorption compared to polymethyl methacrylate (PMMA), which has been used as a plastic material for lenses, and the refractive index change due to water absorption is greatly improved. Has been. However, the temperature dependency of the optical characteristics has not been solved yet, and the temperature dependency of the refractive index is currently one order of magnitude larger than that of the inorganic glass used for the glass lens.

As one of the methods for improving the disadvantages of the optical plastic material as described above, by mixing fillers such as inorganic fine particles with the plastic material, the temperature dependency of the refractive index is improved and the rigidity, heat resistance, etc. Improvements in physical properties have been attempted. Usually, when a resin composition used as an optical plastic and inorganic fine particles are applied, an appropriate surface treatment is performed on the inorganic fine particles and a high light transmittance is maintained. Therefore, it is necessary to use inorganic fine particles whose optical particles and inorganic fine particles are as close as possible and whose primary particle diameter is nano-order. Optical plastic materials usually have a refractive index of about 1.5 to 1.6, and among inorganic fine particles, high refractive inorganic materials (Al ₂ O ₃ , TiO _2, etc.) are coated with low refractive inorganic material SiO ₂ . These materials are considered to be useful materials in terms of refractive index, surface treatment, and particle size distribution (see, for example, Patent Document 1).

However, when mixing cycloolefin polymer (COP), which is usually used as a lens material, and inorganic fine particles containing a SiO ₂ layer produced by a liquid phase method on the surface, moisture contained in the particles during drying and heat mixing with resin There arises a problem that bubbles are generated due to, and particle growth due to silanol residues occurs, resulting in an increase in scattering components in the lens material.

On the other hand, since SiO ₂ produced by the vapor phase method is exposed to a high temperature during production, there are few silanol residues, and bubbles and particle growth are less likely to occur during heat mixing with the resin. Therefore, a lens material produced by heating and mixing with a resin material has an advantage that the scattering component is reduced (see, for example, Patent Document 2). However, vapor phase particles are limited in the types of composite particles that can be produced, and it is difficult to produce uniform particles suitable for high refractive resin materials having a refractive index of 1.5 to 1.6.
JP 2006-219356 A JP 2004-2605 A

An organic-inorganic composite material excellent in transparency by suppressing the generation of bubbles and the increase in primary particle diameter when heating and mixing inorganic fine particles having an SiO ₂ layer on the surface and an optical resin material produced in a liquid phase Is required.

  The object of the present invention is to produce the above-mentioned organic-inorganic composite material, the primary particle diameter of the inorganic powder does not increase during heating / melting mixing with the optical resin material, and transparency when mixed with the optical resin material. An object of the present invention is to provide a method for producing an ensured inorganic fine particle powder.

The present inventor has studied to solve the above problems, and mixed a polymer material having excellent particle dispersibility and high heat resistance temperature and inorganic fine particles having a SiO ₂ layer on the surface by pretreatment in the drying / heating mixing process. Then, after drying, inorganic fine particle powder was prepared by firing at 250 to 550 ° C. Next, it was confirmed that by mixing with an optical resin material, an organic-inorganic composite material with little increase in primary particle diameter, suppressed generation of bubbles, and excellent transparency was produced.

  Specifically, the present invention is solved by the following means.

1. When heated up to 300 ° C. at a heating rate of 10 ° C./min in the atmosphere, 80% by mass or more of a polymer material that is not thermally decomposed and inorganic fine particles containing a SiO ₂ layer at least on the surface are mixed and then dried. And producing an inorganic fine particle powder by firing and manufacturing the inorganic fine particle powder.

  2. 2. The method for producing an inorganic fine particle powder according to 1 above, wherein the content of the polymer material is in the range of 10 to 200% by mass with respect to 100 parts by mass of the inorganic fine particles.

  3. 3. The method for producing an inorganic fine particle powder as described in 1 or 2 above, wherein the firing temperature is 250 to 550 ° C.

  4). An organic-inorganic composite material produced by the method for producing an inorganic fine particle powder according to any one of 1 to 3 above.

  5). 5. An optical element produced using the organic-inorganic composite material described in 4 above.

  By the above-mentioned means of the present invention, a method for producing an organic-inorganic composite material having excellent optical properties and an optical element having excellent optical properties and transparency and excellent thermal stability produced using the organic-inorganic composite material are provided. can do.

Specifically, inorganic fine particles containing at least a SiO ₂ layer on the surface and a polymer material having excellent particle dispersibility and a high heat-resistant temperature are mixed, dried, and fired at 250 to 550 ° C. An organic-inorganic composite material was prepared by mixing the resin material. As a result, haze in the resin material can be significantly suppressed. By applying this organic-inorganic composite material to an optical element, an optical element having excellent optical properties and transparency and excellent thermal stability can be realized. That is, the organic-inorganic composite material of the present invention is suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, etc., and is suitably used as an optical element having excellent optical properties and transparency and excellent thermal stability. Is done.

  The present invention will be described in more detail.

In the method for producing an inorganic fine particle powder of the present invention, inorganic fine particles coated with a SiO ₂ layer having a hydroxyl group are mixed in an optical resin material typified by a cycloolefin polymer. In this case, the mixture is manufactured by mixing with a high heat-resistant binder in order to suppress aggregation of fine bubbles and particles that cause haze, and then drying and baking at 250 to 550 ° C.

  Here, “80% by mass or more is not thermally decomposed” means that 5 mg of binder resin was heated from room temperature to 500 ° C. in an atmospheric pressure atmosphere at a temperature increase rate of 10 ° C./min with a thermal loss analysis (TG) apparatus. Obtained from the heat loss rate when

  The above features are technical features common to the inventions according to claims 1 to 5.

When inorganic fine particles coated with a SiO ₂ layer having a hydroxyl group are melt-mixed with a thermoplastic optical resin material at 200 to 250 ° C. without firing, agglomeration of particles based on fine bubbles or surface silanol groups derived from moisture inside the particles Haze is generated by the coarse particles that are generated. As a result, it has been clarified that the light transmittance of the organic-inorganic composite material is reduced. In addition, when a curable resin and inorganic fine particles are mixed instead of the thermoplastic resin, the same problem occurs when a temperature rising step of 200 ° C. or higher is performed after mixing.

  Therefore, when the inorganic fine particles are dried using a high heat-resistant binder that is not thermally decomposed at 80 ° C. or more at 300 ° C., and calcined at 250 to 550 ° C., the outflow of moisture generated during the mixing is suppressed, and the binder and Inorganic fine particles are retained at high temperatures. As a result, inorganic fine particles having easily agglomerated to such an extent that they can be crushed during mixing while suppressing particle agglomeration, and by using them, an organic-inorganic composite material and an optical element having excellent light transmittance were obtained. It is.

  Hereinafter, the present invention and its components will be described in detail.

《Inorganic fine particles》
The inorganic fine particle powder according to the present invention is used for producing an organic-inorganic composite material by mixing with an optical resin material described later.

The inorganic fine particle powder of the present invention is an inorganic fine particle containing at least a SiO ₂ layer on the surface, and the core portion may be other inorganic components or may be SiO ₂ . In addition, inorganic components other than SiO ₂ may be present on the outermost surface.

The following is a method for producing inorganic fine particles other than the surface SiO ₂ layer, but is not particularly limited, and any known method can be used. As general preparation methods, pyrolysis method (method for obtaining fine particles by thermally decomposing raw materials: spray drying method, flame spray method, plasma method, gas phase reaction method, freeze drying method, heated kerosene method, heated petroleum method Etc.), precipitation method (coprecipitation method), hydrolysis method (salt aqueous solution method, alkoxide method, sol-gel method, etc.), hydrothermal method (precipitation method, crystallization method, hydrothermal decomposition method, hydrothermal oxidation method, etc.) Is mentioned. Among these, the thermal decomposition method, the precipitation method, and the hydrolysis method are preferable in terms of producing inorganic fine particles having a volume dispersion particle size of 30 nm or less. It is also preferable to combine a plurality of these methods.

  As a specific example of the production method, a method for producing silicon oxide includes silicon halide such as silicon fluoride, silicon chloride, and silicon bromide and alkoxysilane as raw materials, and hydrolysis by a reaction system containing water. Thus, oxide fine particles can be obtained. At this time, in order to stabilize the fine particles, a method using an organic acid or an organic amine in combination is also used.

  In addition, a chemical flame is formed by a burner in an oxygen-containing atmosphere that is often used for the production of fine oxide particles, and a metal powder is introduced into the chemical flame in an amount capable of forming a dust cloud and burned. Desired oxide fine particles can also be obtained in the gas phase by a method of synthesizing 5 to 30 nm or reaction of a raw material gas flow and oxygen gas as disclosed in JP-A-2005-218937.

  The inorganic fine particles applicable to the present invention preferably have a volume average dispersed particle size of 30 nm or less, more preferably 1 nm or more and 30 nm or less, and still more preferably 1 nm or more and 10 nm or less. When the volume average dispersed particle size is 1 nm or more, the dispersibility of the inorganic fine particles can be secured, and desired performance can be obtained. Moreover, if the volume average dispersed particle diameter is 30 nm or less, good transparency of the resulting inorganic fine particle dispersed resin composition can be obtained, and a light transmittance of 70% or more can be achieved as an optical element. The volume average dispersed particle diameter here refers to the diameter when inorganic fine particles in a dispersed state are converted into spheres having the same volume. The volume average particle diameter referred to in the present invention can be determined by measurement using TEM / EDX.

  The shape of the inorganic fine particles that can be used in the present invention is not particularly limited, but spherical inorganic fine particles are preferably used from the viewpoint of fluidity. Further, the particle size distribution is not particularly limited, but those having a relatively narrow distribution are preferably used rather than those having a wide distribution from the viewpoint of stability. Part or all of the fine particles may be present as amorphous.

<Types of inorganic fine particles used>
The inorganic fine particles that can be used in the present invention are not particularly limited, and can be appropriately selected from inorganic fine particles that can achieve the purpose of maintaining transparency / improving physical properties by containing inorganic fine particles. Specific examples include oxide fine particles, semiconductor fine particles, metal salt fine particles, and the like. Among these, those that do not cause absorption, light emission, fluorescence, etc. in the wavelength region used as an optical element are preferably used.

As oxide fine particles, the metal constituting the metal oxide is Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb. 1 selected from the group consisting of Sr, Y, Nb, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi and rare earth metals A metal oxide that is a seed or two or more metals can be used. Specifically, for example, silicon oxide, titanium oxide, zinc oxide, aluminum oxide, zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, oxide Magnesium, calcium oxide, strontium oxide, barium oxide, indium oxide, tin oxide, lead oxide, double oxides composed of these oxides, lithium niobate and potassium niobate , Lithium tantalate, the aluminum magnesium oxide (MgAl ₂ O _4), and the like.

  Rare earth oxide can also be used as other oxide fine particles, specifically scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, oxide Examples also include dysprosium, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium oxide. Examples of the metal salt fine particles include carbonates, phosphates, sulfates, and the like, specifically, calcium carbonate, aluminum phosphate, and the like.

The semiconductor fine particles mean fine particles having a semiconductor crystal composition. Specific examples of the semiconductor crystal composition include simple elements of Group 14 elements of the periodic table such as carbon, silicon, germanium, tin, and phosphorus (black phosphorus). A group consisting of a group 15 element such as selenium and tellurium, a compound composed of a group 14 element such as silicon carbide (SiC), tin oxide (IV) ( SnO ₂ ), tin sulfide (II, IV) (Sn (II) Sn (IV) S ₃ ), tin sulfide (IV) (SnS ₂ ), tin sulfide (II) (SnS), tin selenide (II) ( SnSe), tin telluride (II) (SnTe), lead (II) sulfide (PbS), lead selenide (II) (PbSe), lead telluride (II) (PbTe) group 14 elements Compounds with Group 16 elements of the periodic table, boron nitride (BN), boron phosphide (BP), boron arsenide BAs), aluminum nitride (AlN), aluminum phosphide (AlP), aluminum arsenide (AlAs), aluminum antimonide (AlSb), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide (GaAs), antimony Compound of periodic table group 13 element and periodic table group 15 element such as gallium (GaSb), indium nitride (InN), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb) (or the like) III-V group compound semiconductor), aluminum sulfide (Al ₂ S ₃ ), aluminum selenide (Al ₂ Se ₃ ), gallium sulfide (Ga ₂ S ₃ ), gallium selenide (Ga ₂ Se ₃ ), gallium telluride ( Ga ₂ Te ₃ ), indium oxide (In ₂ O ₃ ), indium sulfide (In ₂ S ₃ ), indium selenide (In ₂ Se ₃ ), indium telluride (In ₂ Te ₃ ) and other compounds of group 13 elements of the periodic table and group 16 elements of the periodic table, thallium chloride (I) (TlCl) , Thallium bromide (I) (TlBr), thallium iodide (I) (TlI) compounds such as Group 13 elements and Periodic Table Group 17 elements, zinc oxide (ZnO), zinc sulfide (ZnS) , Zinc selenide (ZnSe), zinc telluride (ZnTe), cadmium oxide (CdO), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), mercury sulfide (HgS), mercury selenide (HgSe), mercury telluride (HgTe) periodic table group 12 element and the periodic table compound of group 16 element such as (or II-VI compound semiconductor), arsenic sulfide (III) (as _{2 3),} selenium arsenic _{(III) (As 2 Se 3} ), telluride arsenic _{(III) (As 2 Te 3} ), antimony sulfide _{(III) (Sb 2 S 3} ), selenium antimony (III) (Sb ₂ Se ₃ ), antimony telluride (III) (Sb ₂ Te ₃ ), bismuth sulfide (III) (Bi ₂ S ₃ ), bismuth selenide (III) (Bi ₂ Se ₃ ), bismuth telluride (III) (Bi) ₂ Te ₃ ) periodic table group 15 element and periodic group 16 element compound, copper oxide (I) (Cu ₂ O), copper selenide (Cu ₂ Se) periodic table Compounds of Group 11 elements and Group 16 elements of the periodic table, copper chloride (I) (CuCl), copper bromide (I) (CuBr), copper iodide (I) (CuI), silver chloride (AgCl), odor Compounds of Group 11 elements of the periodic table and elements of Group 17 of the periodic table, such as silver halide (AgBr), nickel oxide (II) (N O) and other periodic table group 10 elements and periodic table group 16 elements, cobalt oxide (II) (CoO), cobalt sulfide (II) (CoS) and other periodic table group 9 elements and periodic table Compounds with Group 16 elements, compounds of Group 8 elements of the periodic table such as triiron tetroxide (Fe ₃ O ₄ ), iron sulfide (II) (FeS), and Group 16 elements of the periodic table, manganese (II) oxide A compound of a periodic table group 7 element such as (MnO) and a periodic table group 16 element, a periodic table group 6 element such as molybdenum sulfide (IV) (MoS ₂ ), tungsten oxide (IV) (WO ₂ ), etc. Periodic table Group 15 elements such as compounds with Group 16 elements of the periodic table, vanadium oxide (II) (VO), vanadium oxide (IV) (VO ₂ ), tantalum oxide (V) (Ta ₂ O ₅ ), etc. Table compound of group 16 element, titanium oxide _{(TiO 2, Ti 2 O 5} , Ti 2 O 3, Ti 5 O 9 , etc. A compound of a periodic table group 4 element such as a periodic table group 16 element, a compound of a periodic table group 2 element such as magnesium sulfide (MgS) and magnesium selenide (MgSe), and a periodic table group 16 element, Cadmium oxide (II) chromium (III) (CdCr ₂ O ₄ ), cadmium selenide (II) chromium (III) (CdCr ₂ Se ₄ ), copper sulfide (II) chromium (III) (CuCr ₂ S ₄ ), selenium Examples thereof include chalcogen spinels such as mercury (II) chromium (III) (HgCr ₂ Se ₄ ), barium titanate (BaTiO ₃ ), and the like. In addition, G. Schmid et al .; Adv. Mater. 4, 494 (1991), (BN) 75 (BF ₂ ) ₁₅ F ₁₅ and D.C. Fenske et al .; Angew. Chem. Int. Ed. Engl. 29, page 1452 (1990), a semiconductor cluster having a fixed structure such as Cu ₁₄₆ Se ₇₃ (triethylphosphine) ₂₂ reported in the same manner is also exemplified.

<Multiple inorganic fine particles>
These inorganic particles may use one kind of inorganic particles or may use a plurality of kinds of inorganic particles in combination for the purpose of reducing or preventing the refractive index lowering effect. It is also possible to use inorganic particles having a composite composition. Specific examples include a core-shell type, a composite type, and a mixed type.

<< Inorganic fine particles coated with SiO ₂ >>
Inorganic fine particles of the present invention both to prevent the colored surface, SiO ₂ because it can easily be surface modified by a reactive superior surface treatment agent with silanol groups, some of the inorganic fine particles of the present invention at least a surface It has a layer. The SiO ₂ layer is not particularly limited as long as it is an inorganic silica having a silanol group, and a method for producing a silica layer by decomposing chlorosilane at a high temperature in a gas phase, or tetraethoxysilane (hereinafter TEOS) is hydrolyzed in a liquid phase. By decomposing, a SiO ₂ layer can be formed on the surface of the inorganic fine particles.

《Polymer material》
The polymer material of the present invention aims to suppress foaming and aggregation during production by heating to a temperature equal to or higher than that during production of the organic-inorganic composite material while suppressing particle aggregation.

  The polymer material of the present invention is preferably not thermally decomposed by 80 mass% or more, preferably 85 mass% or more under heating conditions up to 300 ° C at a temperature rising rate of 10 ° C / min in the atmosphere. Further preferred.

  Using a thermal analysis apparatus (EXSTAR6000 TG / DTA) manufactured by SII, 5 mg of binder resin was heated from room temperature to 500 ° C. in an atmospheric pressure atmosphere at a temperature increase rate of 10 ° C./min with a thermal loss analysis (TG) apparatus. It was calculated | required from the heat loss rate at the time whether it was the said 80 mass% or more.

There are no particular restrictions on the type of polymer binder, but particle dispersibility, high heat resistance, thickening, etc. are necessary. In particular, the SiO ₂ layer produced in the liquid phase is poly (2-methyl 2-oxazoline). Poly (N-vinylpyrrolidone), poly (N, N-dimethylacrylamide), poly-N-vinylacetamide and the like are preferably used.

(Baking conditions)
There is no particular limitation on the firing atmosphere. The rate of temperature increase varies depending on the type of firing furnace and is not unambiguous, but is about 50 ° C./min to about 300 ° C./hour. The calcination temperature is preferably 250 to 550 ° C. for removing particles, 400 to 550 ° C., more preferably 450 to 550 ° C. for reducing the water surface silanol groups.

  When the temperature exceeds 600 ° C., the dehydration condensation reaction of the silanol group proceeds rapidly, and at the same time, the polymer binder is decomposed, so that the particles may be strongly aggregated and may not be deaggregated even in the melt-kneading step.

  The firing furnace used in the present invention can use a known apparatus and is not particularly limited, but is usually a stationary type, a fluid type, a medium flow type firing furnace, a tunnel furnace, a far infrared firing furnace, a microwave firing furnace, a ventilation firing furnace, A shaft furnace or the like can be used.

  In particular, a commercially available spray pyrolysis apparatus is preferably used to perform high-temperature firing for a short time. The firing time for firing the inorganic fine particles is preferably within 60 minutes, more preferably within 30 minutes. When it is 60 min or more, the silanol groups on the surface of the inorganic fine particles condense, so that the aggregation of the particles proceeds and it becomes difficult to maintain the primary particle size.

  The polymer binder after firing is preferably completely removed from the viewpoint of compatibility with the thermoplastic resin, and examples thereof include degreasing in a flowing air atmosphere and washing with a solvent.

<Surface treatment method for inorganic fine particles>
The inorganic fine particles of the present invention can be improved in affinity with various resin materials by surface modification. The above method is not particularly limited, and any known method can be used. For example, there is a method of modifying the surface of the fine particles by hydrolysis under conditions where water is present. In this method, a catalyst such as an acid or an alkali is preferably used, and it is generally considered that a hydroxyl group on the surface of fine particles and a hydroxyl group generated by hydrolysis of a surface modifier dehydrate to form a bond.

  Examples of the method for modifying the surface of the inorganic fine particles include surface treatment with a surface modifier such as a coupling agent, polymer graft, and surface treatment with mechanochemical.

  Examples of the surface modifier used for the surface modification of the inorganic fine particles include silane coupling agents, silicone oil, titanate, aluminate and zirconate coupling agents. These are not particularly limited, and can be appropriately selected depending on the type of the inorganic fine particles and the optical resin in which the inorganic fine particles are dispersed. Further, two or more surface treatments may be performed simultaneously or at different times.

  Specifically, for example, as a silane-based surface treatment agent, vinylsilazane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, hexamethyldisilazane, etc. are mentioned. Trimethylmethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, hexamethyldisilazane and the like are preferably used.

  Silicone oil treatment agents include straight silicone oil such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, carbinol-modified silicone oil, and methacryl-modified. Silicone oil, mercapto modified silicone oil, phenol modified silicone oil, one-end reactive modified silicone oil, different functional group modified silicone oil, polyether modified silicone oil, methylstyryl modified silicone oil, alkyl modified silicone oil, higher fatty acid ester modified silicone Oil, hydrophilic specially modified silicone oil, higher alkoxy modified silicone oil, higher fat Acid-containing modified silicone oil, modified silicone oil and fluorine-modified silicone oil can be used.

  These treatment agents may be appropriately diluted with hexane, toluene, methanol, ethanol, acetone water or the like.

  Examples of the surface treatment method using the surface modifier include a wet heating method, a wet filtration method, a dry stirring method, an integral blend method, and a granulation method. In the case of modifying the surface of fine particles of 50 nm or less, the dry stirring method is preferably used from the viewpoint of suppressing particle aggregation, but is not limited thereto.

  These surface modifiers may be used alone or in combination, and the properties of the surface-modified fine particles obtained may vary depending on the surface modifier used. Therefore, the affinity with the optical resin used in obtaining the resin composition can be achieved by selecting a surface modifier. The ratio of the surface modification is not particularly limited, but the ratio of the surface modifier is preferably 10 to 99% by mass and more preferably 30 to 98% by mass with respect to the fine particles after the surface modification. preferable.

<Refractive index of inorganic particles>
The refractive index of a resin material used as an optical element is often such that the refractive index nd25 measured using sodium D line (25 ° C.) as a light source is around 1.5 to 1.7, and the refractive index of the inorganic fine particles used is For example, it is preferable to adjust nd25 to a range of 1.5 to 1.7.

  In terms of the refractive index (n1) of the inorganic fine particles used in the present invention, n1 to n2 are 0 from the viewpoint of the light transmittance required for the optical element when the refractive index (n2) of the organic-inorganic composite material used as the optical element is used. .1 or less is preferable. More preferably, it is 0.03 or less, and most preferably 0.01 or less.

  As a method of measuring the refractive index, there are a method of calculating from elemental analysis by EDX, a method based on ASTM D542, a Becke line method, a dispersion method, and the like. In the present invention, values directly calculated by EDX were used.

<Water absorption rate of inorganic particles>
Basically, the water absorption rate of the inorganic particles not subjected to the surface treatment is 5 to 20% by mass, and even the appropriate surface-treated particles have a water absorption of 0.1 to 3% by mass. Inorganic fine particles that do not involve a firing step, such as particles produced by the liquid phase method, some of the water molecules that have been hydrated to ions in the production solution are caused by coordination bonds, hydrogen bonds, and intermolecular forces. It is strongly associated with solute particles and remains entrained in the crystal lattice.

  The dissociation temperature of crystallization water is high, and often remains in the particles even at 150 ° C. or higher, and can be easily dehydrated by heating or mixing. Heated steam is concerned about a decrease in light transmittance due to resin thermal degradation, a decrease in weather resistance due to extraction of additives, and an optical element contamination due to contamination extraction in the kneading apparatus.

  From the above viewpoint, the water absorption of the inorganic fine particles mixed in the organic-inorganic composite material applied as an optical element is preferably 3% by mass or less, more preferably 1% by mass or less, and most preferably 0.2% by mass or less.

<Production of organic-inorganic composite material>
(Master Badge)
Since the inorganic fine particles used in the present invention have a small primary particle size and are easily scattered, a method of preparing an organic-inorganic composite material by mixing with an optical resin in the form of a masterbatch using an optical resin as a binder is used. What is used as a binder is suitably used in consideration of affinity with the final optical resin, particle dispersibility, and the like. In the present invention, optical element resins (host materials), additives such as HALS, and mixtures thereof are preferably used as the masterbatch binder.

(Master batch mixing method)
In the production of the master batch of the present invention, known methods such as a twin-screw kneader, a tumbler mixer, a super mixer, a Henschel mixer, a screw blender, and a ribbon blender can be applied. Particularly, the mixing torque is large and the atmosphere control is easy and continuous. Thus, a biaxial kneader capable of producing an organic-inorganic composite material is preferably used. The concentration may be higher than the inorganic fine particle concentration in the final organic-inorganic composite material. For example, the blending amount of the inorganic fine particles with respect to 100 parts by volume of the binder resin as the resin composition is 25 parts by volume or more and 300 parts by volume or less. It is preferable that When the volume is smaller than 25 parts by volume, the productivity is deteriorated, and when finally produced as an optical element, the volume ratio of the inorganic fine particles is lowered and the effect is not sufficiently exhibited. On the other hand, if the volume is larger than 300 parts by volume, the resin as the binder is insufficient, a uniform composition cannot be obtained, the adhesion at the interface between the inorganic fine particles and the binder becomes insufficient, and voids are generated. When an optical element is manufactured using a masterbatch containing such voids, resin deterioration due to oxygen contained in the voids may occur, or moisture due to air in the voids may be present in the optical elements as bubbles. As a result, the light transmittance is reduced, and thus the optical element is defective.

  In preparing the master batch, the wet mixing method is desirable from the viewpoint that the resin composition is less damaged and can be uniformly mixed. Other advantages of the wet mixing method include prevention of powder scattering, operational convenience, and improved dispersibility. However, the amount of liquid or solution specifically used is appropriately selected depending on the inorganic fine particles and binder composition used.

  The applicable solvent may be any solvent that can dissolve the binder. For example, aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as acetone, methyl ethyl ketone, cyclohexanone, and heptanone, ethyl acetate, acetic acid-t -Esters such as butyl, acetic acid-n-butyl, acetic acid-n-hexyl, halogenated hydrocarbons such as 1,2-dichloroethane, chloroform, chlorobenzene, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether , Ethers such as diethylene glycol diethyl ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2 Pyrrolidone, can be mentioned aprotic polar solvents such as sulfolane. Moreover, these solvents can be used individually or in mixture of 2 or more types.

  The boiling point of the solvent used at atmospheric pressure is preferably 30 to 200 ° C, more preferably 50 to 150 ° C. When the boiling point is less than 30 ° C., it is dangerous in handling. On the other hand, if the boiling point is higher than 150 ° C., it is difficult to remove the solvent, and the final product is adversely affected by the residue of decomposition products and heating.

  The amount of the solvent used when preparing the masterbatch of the present invention is not particularly limited as long as it is within the range in which the binder is dissolved, but 500 to 2000 parts by mass of the solvent is preferable with respect to 100 parts by mass of the binder. When the solvent is less than 500 parts by mass, the binder may not be completely dissolved and the master batch composition may be non-uniform. On the other hand, when it exceeds 2000 parts by mass, productivity is lowered and sufficient torque cannot be obtained during wet mixing, and the prepared master batch composition may be non-uniform. When the amount of residual solvent is 50 ppm or more at the time of preparing the master batch, it is desirable to remove it because it causes a decrease in Tg of the organic-inorganic composite material.

  A biaxial mixing apparatus is desirable as an apparatus for producing a master batch while removing the solvent. In particular, a vent apparatus is preferable in order to prevent moisture absorption of the inorganic fine particles and simultaneously remove the solvent.

  Further, the solvent used at the time of mixing is preferably 2% or less of the total volume from the viewpoint of the influence on the final masterbatch and economical efficiency. Moreover, the influence on the final product of a residual solvent can be suppressed by drying and removing an unnecessary solvent at the time of masterbatch preparation.

<< Inorganic fine particles in organic-inorganic composite materials >>
The volume ratio of inorganic fine particles contained in the final organic-inorganic composite material is 1 to 70 vol%, preferably 10 to 50 vol%. When the inorganic fine particle content of the organic-inorganic composite material is 1 vol% or less, there is a possibility that desired physical properties cannot be improved. Moreover, when the inorganic fine particle content of the organic-inorganic composite material is 70 vol% or more, there is a problem in economic efficiency and moldability.

(Optical resin)
The resin in the present invention is not particularly limited as long as it is a transparent resin generally used as an optical material, such as a thermoplastic resin, a thermosetting resin, and a photocurable resin.

(Thermoplastic resin)
The thermoplastic resin (host material) added to the masterbatch and the organic-inorganic composite material of the present invention is preferably an olefin resin, and particularly preferably a cyclic olefin resin. For example, other existing resins may be used as long as they are within the range described in paragraph numbers 0031 to 0036 of Mitsui Chemicals, JP-A-2003-73559.

  The thermoplastic resin used in the present invention preferably has a glass transition temperature of 80 ° C. or higher and 350 ° C. or lower, and more preferably 100 ° C. or higher and 300 ° C. or lower. If the glass transition temperature is less than 80 ° C, sufficient heat resistance may not be obtained. If the glass transition temperature exceeds 350 ° C, a high temperature is required for molding, which is disadvantageous in terms of process. In addition to this, problems such as discoloration of the material may occur.

The light transmittance is preferably 70% or more, and more preferably 85% or more. The density is preferably from 0.9 g / cm ^{3 to} 2.0 g, more preferably from 0.9 g / cm ^{3 to} 1.5 g.

  The thermoplastic resin in the present invention indicates that it can be softened by heating in a certain temperature range, and product processing can be performed by molding or extrusion in the softened state. Specifically, for example, by pressing in a heated state, the film has a performance capable of forming a film having a thickness of about 0.1 to 5000 μm. In addition, the thermoplastic resin capable of melt molding in the present invention has a melt viscosity capable of melt molding in a thermally stable temperature range, and indicates that molding can be performed by extrusion or injection. Specifically, for example, a temperature at which 5% by mass of the resin is reduced by heating in air, that is, a temperature having a melt viscosity of about 1 to 100 Pascal / second compared to the 5% mass reduction temperature is preferably 30 ° C. or more, preferably Means lower by 50 ° C. or more. By having melt moldability, extrusion molding, injection molding, vacuum molding, blow molding, compression molding, blow molding, calendar molding, laminate molding, etc. are possible, and various molded products such as disks and fibers can be obtained. .

  Specifically, the thermoplastic resin used in the present invention satisfies the above-mentioned optical characteristics, and more preferably, the above-described glass transition temperature, light transmittance, density, and resin processability (thermoplastic and / or Alternatively, it is a resin that also satisfies melt moldability. For example, an acrylic resin, a polycarbonate resin having a cyclic aliphatic chain, a polyester resin having a cyclic aliphatic chain, a polyether resin having a cyclic aliphatic chain, a polyamide resin having a cyclic aliphatic chain, or a polyimide having a cyclic aliphatic chain Examples thereof include resins. More specifically, for example, resins having a structural skeleton represented by chemical formulas (3) to (14) shown in Table 1 can be given, but the present invention is not limited thereto.

  Further, a copolymer in which a part of the cyclic aliphatic chain is replaced with an aromatic ring can be used, and a thiocarbonate, a thioester, a thioether, or the like partially containing sulfur in the bond chain can also be suitably used. In addition, since an aromatic ring and sulfur may be accompanied by a reduction in the Abbe number, it is important to select within a range that does not deviate from the optical properties of the thermoplastic resin presented in the present invention.

  The method for producing the thermoplastic resin used in the present invention is not particularly limited, and any known method can be used. Also, the type and amount of impurities contained in the resin are not particularly limited, but depending on the use, impurities may impair the effects of the present invention, so the total impurity amount is 1% by mass or less, particularly sodium or It is desirable that ionic impurities such as chlorine be 0.5% by mass or less.

  The molecular weight of the thermoplastic resin used in the present invention is not particularly limited, and can be set to an arbitrary molecular weight depending on the application and processing method. However, in consideration of molding processability, the resin is 0.5 g / 100. It is preferable that the value of the logarithmic viscosity measured at 35 ° C. after being dissolved in a solvent capable of being dissolved at a concentration of milliliter is 0.1 to 3.0 deciliter / g.

  In the thermoplastic resin of the present invention, the repeating of the structural unit is not particularly limited, and may be any of an alternating structure, a random structure, a block structure, and the like. Moreover, although the molecular shape used normally is linear, you may use the shape branched. Also, it may be grafted.

  In addition, examples of the thermoplastic resin used in the present invention include a ring-opening polymer hydrogenated product disclosed in Japanese Patent Publication No. 7-121981.

  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 (manufactured by Asahi Glass Co., Ltd.), cyclic olefin resins (for example, ZEONEX (manufactured by Nippon Zeon), Arton (manufactured by JSR), Apel (manufactured by Mitsui Chemicals), TOPAS (manufactured by Chicona), etc.), indene / styrene However, it is not limited to these. It is also preferable to use other resins compatible with these resins. The term “compatible” used in the present invention refers to a completely compatible state that is soluble in a molecular state at an arbitrary ratio and a partially compatible state that is compatible under an arbitrary composition and temperature. Further, when compatibilizing two or more components, the resin after compatibilization is the average of the physical and chemical properties of each component, or has physical and chemical properties that show the best properties of both. For example, when two or more kinds of resins are used, the water absorption rate is considered to be approximately equal to the average value of the water absorption rates of the individual resins, and the average water absorption rate may be 0.2% or less.

(Curable resin)
As the curable resin used in the present invention, it can be cured by any of ultraviolet and electron beam irradiation or heat treatment, and after being mixed with inorganic fine particles in an uncured state, it is transparent by curing. Any resin composition can be used without particular limitation, and epoxy resins, vinyl ester resins, silicone resins and the like are preferably used. As an example, an epoxy resin and its constituent composition will be described below, but the present invention is not limited to these.

(Hydrogenated epoxy resin)
Examples of the curable resin used in the present invention include a hydrogenated epoxy resin, and an epoxy resin obtained by hydrogenating an aromatic epoxy resin is preferably used. Examples of this epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, 3,3 ', 5,5'-tetramethyl-4,4'-biphenol type epoxy resin, or 4,4'-biphenol type. Biphenol type epoxy resin such as epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, naphthalenediol type epoxy resin, trisphenylol methane type epoxy resin, tetrakisphenylol ethane type epoxy resin And an epoxy resin obtained by hydrogenating an aromatic ring of a phenol dicyclopentadiene novolac type epoxy resin. Among these, hydrogenated epoxy resins obtained by directly hydrogenating the aromatic rings of bisphenol A type epoxy resin, bisphenol F type epoxy resin and biphenol type epoxy resin are particularly preferable in that an epoxy resin having a high hydrogenation rate can be obtained.

  Moreover, 5-50 mass% of alicyclic epoxy resins obtained by epoxidizing alicyclic olefins can be added to the hydrogenated epoxy resin and used in combination. A particularly preferred alicyclic epoxy resin is 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate. When this alicyclic epoxy resin is blended, the blending viscosity of the epoxy resin composition can be reduced. Can be improved.

(Acid anhydride curing agent)
The acid anhydride curing agent in the epoxy resin composition of the present invention is preferably an acid anhydride curing agent having no carbon-carbon double bond in the molecule. Specifically, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, hydrogenated nadic anhydride, hydrogenated methyl nadic anhydride, hydrogenated trialkylhexahydrophthalic anhydride, 2,4-diethylglutaric anhydride, etc. Is mentioned. Among these, hexahydrophthalic anhydride and / or methyl hexahydrophthalic anhydride are particularly preferable in that they are excellent in heat resistance and a colorless cured product can be obtained.

  The addition ratio of the acid anhydride curing agent varies depending on the epoxy equivalent of the epoxy resin, but is preferably blended within a range of 40 to 200 parts by mass with respect to 100 parts by mass of the epoxy resin.

(Curing accelerator)
A curing accelerator can be used in the epoxy resin composition of the present invention for the purpose of accelerating the curing reaction between the epoxy resin and the acid anhydride. Examples of curing accelerators include tertiary amines and salts thereof, imidazoles and salts thereof, organic phosphine compounds, zinc octylates, tin octylates and other organic acid metal salts, and particularly preferred curing accelerators are Organic phosphine compounds. The mixing ratio of the curing accelerator to be added is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the hydrogenated anhydride curing agent. Outside this range, the balance of heat resistance and moisture resistance of the cured epoxy resin is deteriorated, which is not preferable.

<Resin additive>
In the production process and processing process of the optical resin used in the present invention, various kinds of additives may be used alone or in combination as necessary.

  Although there is no special designation for the additive used in the present invention, it is generally used as a heat stabilizer, antioxidant, light stabilizer, plasticizer, impact modifier, extender, antistatic agent, Examples include mold release agents and various processing aid fillers. Various additives as described above are commonly used and are known to those skilled in the art. Specific examples of such additives are described in R.A. Gachter and H.C. Muller, Plastics Additives Handbook, 4th edition, 1993. Moreover, the range can be used suitably in the range which does not impair the effect as described in invention. The additive may be added at any timing from the resin manufacturing process to the final product processing process.

  Although the specific example of the main thing is given to the following among each resin additive, it is not limited to these.

《Plasticizer》
The plasticizer is not particularly limited, however, phosphate ester plasticizer, phthalate ester plasticizer, trimellitic ester plasticizer, pyromellitic acid plasticizer, glycolate plasticizer, citrate ester A plasticizer, a polyester plasticizer, etc. can be mentioned.

  In the phosphate ester plasticizer, for example, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. Trimellitic plasticizers such as diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, diphenyl phthalate, dicyclohexyl phthalate, etc. For pyromellitic acid ester plasticizers such as phenyl trimellitate, triethyl trimellitate, etc. Examples of glycolate plasticizers such as tilpyromelitate, tetraphenylpyromellitate, and tetraethylpyromellitate include triacetin, tributyrin, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, and butylphthalylbutyl glycolate. In the citrate plasticizer, for example, triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n- (2-ethylhexyl) citrate, etc. Can be mentioned.

"Antioxidant"
Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. Among them, phenolic antioxidants, particularly alkyl-substituted phenolic antioxidants are preferable. By blending these antioxidants, it is possible to prevent lens coloring and strength reduction due to oxidative degradation during molding without reducing transparency, heat resistance and the like. These antioxidants can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but the polymer 100 according to the present invention. Preferably it is 0.001-5 mass parts with respect to a mass part, More preferably, it is 0.01-1 mass part.

  A conventionally well-known thing can be used as a phenolic antioxidant, 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, pentaerythrityl-tetrakis [3- (3,5-di- -Butyl-4-hydroxyphenyl) propionate], thiodiethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,3,5-trimethyl-2,4,6- Alkyl-substituted phenols such as tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene and triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate) Compound; 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1,3,5-triazine, 4-bisoctylthio-1,3,5-triazine, Triazine group-containing phenols such as 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3,5-triazine Lumpur-based compounds; and the like.

  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, tris- (2,6-dimethylphenyl) phosphite, 10- (3,5-di- monophosphite compounds such as t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 4,4′-butylidene-bis (3-methyl-) 6-t-butylphenyl-di-tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl) Sulfonyl - di - alkyl (C12-C15) phosphite), 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.

  Examples of the sulfur-based antioxidant include dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3-thiodiprote. Pionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, etc. Can be mentioned.

<Light resistance stabilizer>
Examples of the light-resistant stabilizer include benzophenone-based light-resistant stabilizer, benzotriazole-based light-resistant stabilizer, hindered amine-based light-resistant stabilizer, etc., but in the present invention, from the viewpoint of lens transparency, color resistance, etc., hindered amine-based It is preferable to use a light-resistant stabilizer. Among the hindered amine light-resistant stabilizers (hereinafter referred to as HALS), those having a Mn in terms of polystyrene measured by GPC using tetrahydrofuran (THF) as a solvent are preferably 1,000 to 10,000. What is -5,000 is more preferable, and what is 2,800-3,800 is especially preferable. When Mn is too small, when HALS is blended by heat-melting and kneading into a block copolymer, a predetermined amount cannot be blended due to volatilization, and foaming or silver streak occurs during heat-melt molding such as injection molding. Stability is reduced. Further, when the lens is used for a long time with the lamp turned on, a volatile component is generated as a gas from the lens. Conversely, if Mn is too large, the dispersibility in the block copolymer is lowered, the transparency of the lens is lowered, and the effect of improving light resistance is reduced. Therefore, in the present invention, a lens excellent in processing stability, low gas generation and transparency can be obtained by setting the HALS Mn in the above range.

  Specific examples of such HALS include N, N ′, N ″, N ′ ″-tetrakis- [4,6-bis- {butyl- (N-methyl-2,2,6,6-tetramethylpiperidine. -4-yl) amino} -triazin-2-yl] -4,7-diazadecane-1,10-diamine, dibutylamine and 1,3,5-triazine and N, N'-bis (2,2,6 , 6-tetramethyl-4-piperidyl) butylamine, poly [{(1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} { (2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], bis (2,2,6,6 -Tetramethyl-4-piperidyl) sebacate, 1,6- A polycondensation product of xylenediamine-N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) and morpholine-2,4,6-trichloro-1,3,5-triazine, Poly [(6-morpholino-s-triazine-2,4-diyl) (2,2,6,6-tetramethyl-4-piperidyl) imino] -hexamethylene [(2,2,6,6-tetramethyl -4-piperidyl) imino] and other high molecular weight HALS in which a plurality of piperidine rings are bonded via a triazine skeleton; dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol Polymer, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis (2-hydroxy-1,1-dimethylethyl) 2,4,8,10 such mixed ester of tetra oxa spiro [5,5] undecane, piperidine ring linked to a high molecular weight HALS, and the like via an ester bond.

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

(Optical element)
An optical element according to the present invention is an optical element using an organic-inorganic composite material produced by the above manufacturing method. Below, the manufacturing method of the said optical element, etc. are demonstrated in detail.

<< Optical Element Manufacturing Method >>
In order to obtain a resin composition in which inorganic fine particles are highly dispersed, a method for producing an organic-inorganic composite material according to the present invention is carried out by using a melt kneading apparatus while mixing a master batch and a dilution resin composition as a host material. The method of giving and producing is preferably used. The optical resin as the host material is preferably a resin that is the same as or compatible with the resin composition used in the masterbatch from the viewpoint of transparency, and has optical stability such as thermal stability and refractive index such as glass transition point. It is more preferable to use the same resin composition from the viewpoint of stability. The proportion of inorganic fine particles contained in the finally prepared resin composition is usually about 5 to 50% by volume. When the proportion of the inorganic fine particles contained in the resin composition is significantly small, the physical property improvement effect required by the inclusion of the filler cannot be expected. Further, when the ratio specified above is exceeded, it takes time for uniform mixing in the kneading apparatus, resulting in deterioration of the resin, and adhesion of the inorganic fine particle dispersed resin composition to the inner wall surface of the kneading apparatus is a problem. Become.

  Further, the mixing with the resin is preferably carried out in an inert gas atmosphere such as Ar, N2, etc., not in the air, in order to prevent functional deterioration due to oxidation.

  Specific kneaders include KRC Kneader (manufactured by Kurimoto Iron Works), Polylab System (manufactured by HAAKE), Nanoplast Mill (manufactured by Toyo Seiki Seisakusho), Nauta Mixer Bus Co. Kneader (Buss) ), TEM type extruder (Toshiba Machine Co., Ltd.), TEX twin screw kneader (Nihon Steel Works), PCM kneader (Ikegai Iron Works Co., Ltd.), three roll mill, mixing roll mill, kneader (above, Inoue Manufacturing Co., Ltd.) Company-made), kneedex (made by Mitsui Mining Co., Ltd.), MS pressure kneader, nider ruder (made by Moriyama Seisakusho), Banbury mixer (made by Kobe Steel).

(Mixing conditions)
In the present invention, when the degree of mixing of the masterbatch and the resin composition is insufficient, there is a concern that the optical properties such as the refractive index, the Abbe number, and the light transmittance may be affected. Sufficient mixing is desirable because it may adversely affect resin processability such as moldability. It is important to select the method for the degree of mixing in consideration of the characteristics of the resin composition to be used. When the atmosphere control of the apparatus and continuous productivity are taken into consideration, it is preferable to use a twin-screw kneader. In addition, a rotor, a kneader, or the like can be used if the atmosphere can be controlled with high torque.

<< Method for producing molded article for optical element using thermoplastic resin >>
The molding method of the resin composition of the optical element using the organic-inorganic composite material of the present invention is not particularly limited, but a molded product having excellent characteristics such as low birefringence, mechanical strength, and dimensional accuracy. In order to obtain, the melt molding method is preferable.

  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.

  The molding conditions are appropriately selected depending on the purpose of use or the molding method. For example, the temperature of the resin composition in injection molding (in the case of a resin alone or in a mixture of both resin and additive) is moderate during molding. From the viewpoint of imparting excellent fluidity to the resin to prevent sink marks and distortion of the molded product, preventing the occurrence of silver streak due to thermal decomposition of the resin, and effectively preventing yellowing of the molded product. The range of 400 ° C is preferable, more preferably in the range of 200 ° C to 350 ° C, and particularly preferably in the range of 200 ° C to 330 ° C.

<< Method for producing molded article for optical element using thermosetting resin >>
The thermosetting resin used in the present invention can be cured by any of ultraviolet and electron beam irradiation or heat treatment, and includes a curable monomer and inorganic fine particles, and a plasticizer and an antioxidant as necessary. It is obtained by preparing and then curing a resin composition to which the additive is added.

  As a method of curing the resin composition, when the resin composition is ultraviolet and electron beam curable, a resin composition in which a photopolymerization initiator is added to a light-transmitting mold having a predetermined shape as necessary. After filling or coating on a substrate, it may be cured by irradiating with ultraviolet rays and electron beams.

  Examples of the photopolymerization initiator used here include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, tri Phenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoinpropyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4- Photoradical initiation such as isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one Etc. The.

  On the other hand, if the resin composition is thermosetting, after preparing a resin composition to which a thermal polymerization initiator such as a thermal radical generator is added, if necessary, thermosetting molding by compression molding, transfer molding, injection molding, etc. can do. Examples of the thermal polymerization initiator used here include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4- Azo compounds such as methoxy-2,4-dimethylvaleronitrile), benzoyl peroxide, lauroyl peroxide, t-butylperoxypivalate, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, etc. Organic peroxides and the like.

  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 shape or a sheet shape, and has a low birefringence and a transparency. It is used as an optical resin lens, which is one of the optical elements of the present invention, because of its excellent properties, mechanical strength, heat resistance, and low water absorption, but is also suitable as other optical components.

<Examples of application to optical elements>
The organic-inorganic composite material for an optical element of the present invention can be obtained by the above production method. Specific examples of application to the optical element are as follows.

  For example, as an optical lens or an optical prism, an imaging 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, a WORM (recordable optical disk), MO (rewritable optical disc; magneto-optical disc), MD (mini disc), optical disc pick-up lens such as DVD (Digital Versatile Disc); laser scanning system lens such as laser beam printer fθ lens, sensor lens; camera 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 (MiniDisc), DVD (Digital Versatile 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 a pickup lens or a laser scanning system lens that requires low birefringence, and is most suitably used for a pickup lens.

  The organic-inorganic composite material for an optical element produced by using the present invention has excellent temperature characteristics and is suitably used as a high-density optical disk lens using a blue-violet laser light source.

  Among the above-described molded products, it is suitably used as an optical element such as a pickup lens or a laser scanning system lens that requires low birefringence. Hereinafter, referring to the drawings, the organic / inorganic optical element according to this embodiment is used. An optical pickup device 1 using an optical element formed of a composite material will be described.

  As shown in FIG. 1, the optical pickup device 1 in this embodiment includes three types of semiconductor laser oscillators LD1, LD2, and LD as light sources. Among these, the semiconductor laser oscillator LD1 emits a light beam having a specific wavelength of 350 to 450 nm, for example, 405 nm and 407 nm, for the BD (or AOD) 10. Further, the semiconductor laser oscillator LD2 emits a light beam having a specific wavelength in a wavelength of 620 to 680 nm for the DVD 20. Further, the semiconductor laser LD3 emits a light beam having a specific wavelength in the range of 750 to 810 nm for the CD30.

  In the optical axis direction of the blue light emitted from the semiconductor laser oscillator LD1, a shave SH1, a splitter BS1, a collimator CL, splitters BS4 and BS5, and an objective lens 15 are sequentially arranged from the lower side to the upper side in FIG. The optical information recording medium BD10, DVD20 or CD30 is arranged at a position facing the objective lens 15. Further, a cylindrical lens L11, a concave lens L12, and a photodetector PD1 are sequentially disposed on the right side of the splitter BS1 in FIG.

  In the optical axis direction of the red light emitted from the semiconductor laser oscillator LD2, splitters BS2 and BS4 are sequentially arranged from the left to the right in FIG. Further, a cylindrical lens L21, a concave lens L22, and a photodetector PD2 are sequentially disposed below the splitter BS2 in FIG.

  In the optical axis direction of the light emitted from the semiconductor laser oscillator LD3, splitters BS3 and BS5 are sequentially arranged from the right to the left in FIG. A cylindrical lens L31, a concave lens L32, and a photodetector PD3 are sequentially arranged below the splitter BS3 in FIG.

  The objective lens 15 which is an optical element is disposed opposite to the BD10, DVD20 or CD30 as an optical information recording medium, and the light emitted from each of the semiconductor laser oscillators LD1, LD2 and LD3 is BD10, DVD20 or CD30. It is supposed to concentrate on. Such an objective lens 15 includes a two-dimensional actuator 2, and the objective lens 15 is movable in the vertical direction by the operation of the two-dimensional actuator 2.

  Next, the operation of the optical pickup device will be described.

  Since the optical pickup device 1 in the present embodiment operates differently depending on the type of the recording medium, details of the operation modes for the BD 10, the DVD 20, and the CD 30 will be described below.

  First, the operation of the optical pickup device 1 for the BD 10 will be described.

  The semiconductor laser oscillator LD1 emits light at the time of recording information on the BD 10 or at the time of reproducing information recorded on the BD 10. As shown in FIG. 1, the light becomes a light beam L1, is shaped by passing through the shave SH1, passes through the splitter BS1, and is collimated by the collimator CL. Then, the light passes through each of the splitters BS4 and BS5 and the objective lens 15, and forms a condensed spot on the recording surface 10a of the BD10.

  The light that forms the condensed spot is modulated by the information pits on the recording surface 10a of the BD 10 and reflected by the recording surface 10a. The reflected light passes through the objective lens 15, the splitter BS5, and the collimator CL, is reflected by the splitter BS1, and then passes through the cylindrical lens L11 to give astigmatism. Thereafter, the light passes through the concave lens L12 and is received by the photodetector PD1. Thereafter, such an operation is repeatedly performed, and the operation of recording information on the BD 10 and the operation of reproducing information recorded on the BD 10 are completed.

  Next, the operation of the optical pickup device 1 for the DVD 20 will be described.

  The semiconductor laser oscillator LD2 emits light at the time of recording information on the DVD 20 or at the time of reproducing information recorded on the DVD 20. As shown in FIG. 1, the light becomes a light beam L2, passes through the splitter BS2, and is reflected by the splitter BS4. The reflected light beam L2 passes through the splitter BS5 and the objective lens 15, and forms a condensed spot on the recording surface 20a of the DVD 20.

  The light forming the condensed spot is modulated by the information pits on the recording surface 20a of the DVD 20 and reflected by the recording surface 20a. The reflected light is transmitted through the objective lens 15 and the splitter BS5, reflected by the splitters BS4 and BS2, and then transmitted through the cylindrical lens L21 to give astigmatism. Thereafter, the light passes through the concave lens L22 and is received by the photodetector PD2. Thereafter, such an operation is repeatedly performed, and the operation of recording information on the DVD 20 and the operation of reproducing information recorded on the DVD 20 are completed.

  Finally, the operation of the optical pickup device 1 for the CD 30 will be described.

  Light is emitted from the semiconductor laser oscillator LD3 when information is recorded on the CD 30 or when information recorded on the CD 30 is reproduced. As shown in FIG. 1, the emitted light becomes a light beam L3, passes through the splitter BS3, and is reflected by the splitter BS5. The reflected light beam L3 passes through the objective lens 15 and forms a condensed spot on the recording surface 30a of the CD 30.

  The light forming the focused spot is modulated by the information pits on the recording surface 30a of the CD 30, and reflected by the recording surface 30a. The reflected light is transmitted through the objective lens 15, reflected by the splitters BS5 and BS3, and then transmitted through the cylindrical lens L31 to give astigmatism. Thereafter, the light passes through the concave lens L32 and is received by the photodetector PD3. Thereafter, such an operation is repeatedly performed, and the recording operation of information on the CD 30 and the reproducing operation of information recorded on the CD 30 are completed.

  In the optical pickup device 1, the spot of the light detectors PD1, PD2, and PD3 is recorded at the time of recording information on the BD 10, DVD 20 or CD 30 and at the time of reproducing information recorded on the BD 10, DVD 20 or CD 30. Focus detection or track detection is performed by detecting a change in light amount due to a shape change or a position change. In such an optical pickup device 1, the two-dimensional actuator 2 transmits light from the semiconductor laser oscillators LD1, LD2, and LD3 to the BD10, DVD20, or CD30 based on the detection results of the photodetectors PD1, PD2, and PD3. The objective lens 15 is moved so as to form an image on the recording surfaces 10a, 20a, and 30a, and light from the semiconductor laser oscillators LD1, LD2, and LD3 is formed on predetermined tracks on the recording surfaces 10a, 20a, and 30a. The objective lens 15 is moved.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

(Inorganic fine particles 1)
After mixing 8 parts by mass of γ-alumina TM-300 (primary particle diameter 7 nm) made by Daimei Chemical with 100 parts by mass of 28% ammonia water, 100 parts by mass of water and 300 parts by mass of ethanol, Kotobuki Giken Bead Mill Disperser (Ultra Apex Mill) ) Was used for dispersion mixing. Thereafter, 3 parts by mass of tetraethoxysilane manufactured by Kanto Chemical Co., Ltd. was dropped over 8 hours, subjected to desalting and washing with water and ethanol, and then dried at 100 ° C. to produce silica-coated alumina particles. Thereafter, polymer binder 1 (Poly-N-vinylacetamide (PNVA) polymerization degree 15 manufactured by Showa Denko) was mixed with parts by mass shown in Table 2 and 100 parts by mass of Et-OH, and vacuum dried at 90 ° C. for 24 hours.

After firing at a predetermined temperature and time in a firing furnace, PNVA was removed by washing with Et-OH. Thereafter, 1.5 parts by mass of hexamethyldisilazane manufactured by Shin-Etsu Chemical Co., Ltd. was mixed in a dry N ₂ atmosphere, and then mixed at 250 ° C. for 8 hours. Thereafter, it was dried under reduced pressure at 250 ° C. in an N ₂ atmosphere to prepare a surface-treated SiO ₂ -coated alumina particle-inorganic fine particle powder 1.

(Inorganic fine particles 2)
After drying under reduced pressure Nippon Aerosil Ltd. silicon oxide RX200 (primary particle size 13 nm) 10 parts by N ₂ atmosphere at 120 ° C., after mixing Etsu Chemical hexamethyldisilazane 4 parts by weight under a dry N ₂ atmosphere 250 Mix at 8 ° C. for 8 h. Thereafter, surface-treated SiO ₂ particles were produced by drying under reduced pressure at 250 ° C. in an N ₂ atmosphere. Thereafter, the same treatment as in the case of the inorganic fine particles 1 was performed to prepare an inorganic fine particle powder 2.

(Thermoplastic resin 1)
The cycloolefin polymer APEL5014 manufactured by Mitsui Chemicals was used as the thermoplastic resin 1.

(Thermoplastic resin 2)
Sumitomo Chemical's polymethylmethacrylate Sumipex MGSS was used as thermoplastic resin 2.

(Preparation of masterbatch, organic-inorganic composite material and optical element using thermoplastic resin)
70 parts by volume of inorganic fine particles sufficiently dried in a dry N ₂ atmosphere, 60 parts by volume of thermoplastic resin for binder that was sufficiently pre-dried at 24 ° C. at a temperature 10 ° C. lower than the glass transition temperature (Tg), and dehydration treatment The slurry which mixed 1200 volume parts of cyclohexane which performed was mixed and deaerated with the twin-screw extruder by a technobel company, and the masterbatch was produced. Degassing was performed until the remaining amount of the solvent was 30 ppm or less, and a master batch was produced.

  Subsequently, the binder thermoplastic resin used as a host resin and the masterbatch were continuously kneaded as a host resin by using a biaxial kneader manufactured by Technobel Co., Ltd., so that the inorganic fine particle filling amount was 25 vol%. An inorganic composite material was prepared. The kneading temperature at this time was Tg + 40 ° C. Thereafter, the organic-inorganic composite material for the optical element was molded using an injection molding machine to produce an optical element which is a test plate having a thickness of 1 mm, a width of 20 mm, and a length of 50 mm.

As a comparative example, polymer binder 2: polyethylene glycol (PEG) # 400 manufactured by Kanto Chemical
Polymer binder 3: It was produced in the same manner as in Example using polyvinyl pyrrolidone # 20000 manufactured by Nippon Shokubai.

(Curable resin 1)
The thermosetting 1-adamantyl methacrylate was used as the curable resin 1.

(Preparation of masterbatch, organic-inorganic composite material and optical element using curable resin)
And inorganic fine particles was sufficiently dried under N ₂ atmosphere, curable monomer was thoroughly degassed dry under 20 ° C. N ₂ atmosphere, after mixing adjusts 1-adamantyl methacrylate to be inorganic filling ratio 25 parts by volume , 1-1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane 0.05 part by volume as a radical polymerization initiator was mixed, and a desktop three-roll mill (RM-1, Co., Ltd.) Using Irie Shokai). The resulting dispersion was defoamed using a rotating and rotating mixer (Awatori Nertaro AR-100, manufactured by Shinky Co., Ltd.), and then a test plate mold having a thickness of 1 mm, a width of 20 mm, and a length of 50 mm. And cured in an oven at 110 ° C. for 1 hour and then at 150 ° C. for 3 hours to obtain a colorless and transparent optical element.

<Evaluation of optical element>
(Measurement of light transmittance)
The transmittance T1 (%) at a wavelength of 405 nm with respect to the thickness direction (1 mm thickness) of a test plate (optical element) having a thickness of 1 mm, a width of 20 mm, and a length of 50 mm is measured according to ASTM D-1003. It measured using total UV-3150.

(Measurement of dn / dT (refractive index temperature change))
Using a test plate (optical element) having a thickness of 1 mm, a width of 20 mm, and a length of 50 mm while changing the sample temperature from 10 ° C. to 60 ° C., an automatic refractometer KPR-200 manufactured by Kalnew Optical Industry Co., Ltd. The refractive index at a wavelength of 405 nm was measured. Subsequently, the temperature change rate of the refractive index at 10 ° C. to 60 ° C. was obtained as dn / dT.

(With or without foaming)
A test plate (optical element) having a thickness of 1 mm, a width of 20 mm, and a length of 50 mm was observed with an optical microscope and SEM, and the amount of spherical foreign matter (bubbles) having a particle size of 100 nm or more was evaluated according to the following criteria.
○: Foam hardly observed Δ: Trace amount of foam confirmed x: Foam of 1% or more confirmed in volume conversion Table 2 shows the results obtained as described above.

  Conventionally, polymethylmethacrylate (optical element 10: Reference Example 2), APEL5014 (optical element 9: Reference Example 1) made of Mitsui Chemicals, which is a cyclic olefin resin, and the like are applied as optical element materials. However, the polymethyl methacrylate of Reference Example 2 has a small refractive index variation with respect to a temperature change, but as an optical element, for example, has poor durability when irradiated with light having a wavelength of 405 nm over a long period of time, and has a water absorption property. Since it is expensive, it has a problem as a resin material for optical elements. On the other hand, APEL 5014 described in Reference Example 1 has high transparency, durability, and water resistance, and is a widely used resin material. However, the problem is that the refractive index variation with respect to temperature change is large. It was one. As a means for improving the refractive index fluctuation in this APEL 5014, attempts have been made to improve by adding inorganic fine particles, but aluminum oxide prepared by a conventionally known method has a high water absorption rate, and silica coating or surface treatment is performed. Even so, as shown in Comparative Example 1, fine foaming and particle aggregation occur during kneading, resulting in a decrease in light transmittance.

  Further, as shown in Comparative Examples 2 to 5, even when firing was performed using a polymer binder, the particles were hardly aggregated and could not be redispersed at the time of compositing.

  On the other hand, as is clear from the results of the examples shown in Table 2, the production method of the present invention can produce fired particles that are easily loosened by using a high heat-resistant polymer binder. The inorganic composite material can suppress foaming and haze in the molded body, and can greatly suppress a decrease in light transmittance. It can be seen that the optical element produced using the organic-inorganic composite material of the present invention is excellent in light transmittance, small in dn / dT with respect to environmental changes (temperature changes), and excellent in refractive index stability.

It is the schematic which shows the structure of the optical pick-up apparatus using the optical element which concerns on this invention.

Explanation of symbols

  15 Objective lens (optical element)

Claims (5)

When heated up to 300 ° C. at a heating rate of 10 ° C./min in the atmosphere, 80% by mass or more of a polymer material that is not thermally decomposed and inorganic fine particles containing a SiO ₂ layer at least on the surface are mixed and then dried. And producing an inorganic fine particle powder by firing and manufacturing the inorganic fine particle powder. The method for producing inorganic fine particle powder according to claim 1, wherein the content of the polymer material is in the range of 10 to 200% by mass with respect to 100 parts by mass of the inorganic fine particles. The method for producing an inorganic fine particle powder according to claim 1 or 2, wherein the firing temperature is 250 to 550 ° C. An organic-inorganic composite material produced by the method for producing an inorganic fine particle powder according to any one of claims 1 to 3. An optical element manufactured using the organic-inorganic composite material according to claim 4.

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