JP2007154159A - Organic inorganic composite material and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic inorganic composite material having a small change in refractive index with temperature and excellent transparency. <P>SOLUTION: The organic inorganic composite material is an organic inorganic composite material comprising inorganic micro-particles dispersed in a resin. In the organic inorganic composite material, the inorganic micro-particles in a state of primary particles or in an aggregated state of a plurality of primary particles are dispersed in the resin. When the particle diameter of the dispersed particles is D and the intercentral distance of the optional dispersed particles and the dispersed particles adjacent thereto is L, the particle diameter D and the intercentral distance L satisfy both conditions specified by formulas (1) and (2). D<SB>50</SB>&le;30 nm (1) (wherein, D<SB>50</SB>means the particle diameter D so that the cumulative number is 50% of the total number in the number distribution function of the dispersed particles) and Lp&le;30 nm (2) (wherein, Lp means the intercentral distance L in the frequency distribution function of the intercentral distance L). <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to an organic-inorganic composite material suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, etc., having a small refractive index change rate due to temperature and excellent in transparency, 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 a medium) such as MO, CD, and DVD is provided with an optical pickup device. The optical pickup device includes an optical element unit that irradiates a medium with light having a predetermined wavelength emitted from a light source, and receives the reflected light with a light receiving element. The optical element unit receives the light from a reflection layer or a light receiving medium of the medium. An optical element such as a lens for condensing light by the element is included.

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

  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, an optical plastic material such as a cyclic olefin has an extremely low water absorption as compared with PMMA that has been used as a conventional plastic for lenses, and the change in refractive index due to water absorption is greatly improved. However, the temperature dependence of the optical properties has not yet been solved, and the temperature dependence of the refractive index is currently one order of magnitude greater than that of inorganic glass.

  As one method for improving the disadvantages of the optical plastic material as described above, a method using a fine particle filler has been proposed. For example, in Patent Document 2, as a method for reducing the temperature dependency of refractive index | dn / dT |, fine particles with dn / dT> 0 are dispersed in a polymeric host material with dn / dT <0. Optical products have been proposed.

However, in the case of the above-described optical plastic material in which fine particles are dispersed, it is necessary to mix a large amount of inorganic fine particles in order to reduce | dn / dT |. In this case, the inorganic fine particles are scattered by light. A decrease in light transmittance is expected. As a technique for solving this problem, Patent Document 3 proposes a technique for suppressing a decrease in light transmittance by controlling the particle size distribution of inorganic fine particles in a resin. Further, although different from the purpose of suppressing a decrease in light transmittance, Patent Document 4 discloses silica-based inorganic filler particles or aggregates in a thermoplastic resin-inorganic composite material containing a silica-based inorganic filler. In addition, a composite material in which the distance between the adjacent particles or aggregates is 0.1 μm or more and the independent silica-based filler is 50% by mass or less has been proposed.
JP 2002-105131 A (page 4) JP 2002-207101 A (Claims) JP 2006-160992 A (Claims) JP 2004-143364 A (Claims)

However, the technique described in Patent Document 3 is insufficient to realize a light transmittance that can withstand practical use, and it cannot be said that the problem has been solved yet. On the other hand, in the technique described in Patent Document 4, there is no description about the size of the aggregate, and it does not provide an organic-inorganic composite material having a high light transmittance.
The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic-inorganic composite material and an optical element that have a small change in refractive index due to temperature and are excellent in transparency.

In order to solve the above problems, the first invention
An organic-inorganic composite material in which inorganic fine particles are dispersed in a resin, wherein the inorganic fine particles are dispersed in the resin in a primary particle state or in a state where a plurality of primary particles are aggregated. When the diameter is defined as D and the center-to-center distance between any of the dispersed particles and the dispersed particles adjacent thereto is defined as L, the particle diameter D and the center-to-center distance L
Satisfying both conditions defined by the following formulas (1) and (2).
D ₅₀ ≦ 30 nm (1)
Lp ≦ 30 nm (2)

However, in the above formula (1), “D ₅₀ ” means the particle diameter D at which the cumulative number becomes 50% of the total number in the number distribution function of the dispersed particles. In the above equation (2), “Lp” means the peak center distance L in the frequency distribution function of the center distance L.

In the organic-inorganic composite material according to the first invention,
It is preferable that the center distance L satisfies the condition defined by the following formula (3).
Lp ≦ 20 nm (3)

In the organic-inorganic composite material according to the first invention,
The center distance L preferably satisfies the condition defined by the following formula (4).
L ₉₅ ≦ 60 nm (4)

However, in the above formula (4), “L ₉₅ ” means the center distance L at which the cumulative frequency is 95% of the total frequency in the frequency distribution function of the center distance L.

In the organic-inorganic composite material according to the first invention,
When the volume fraction of the inorganic fine particles in the organic-inorganic composite material is defined as Φ, the volume fraction Φ preferably satisfies the condition defined by the following formula (5).
0.2 ≦ Φ ≦ 0.6 (5)

In the organic-inorganic composite material according to the first invention,
The inorganic fine particles are preferably a composite oxide in which a silicon oxide and one or more metal oxides other than silicon are combined.

The second invention is
An optical element formed using the organic-inorganic composite material according to the first invention.

  According to the first and second inventions, it is possible to provide an organic-inorganic composite material and an optical element that have a small refractive index change rate due to temperature and are excellent in transparency (see the following examples).

Hereinafter, the best mode for carrying out the present invention will be described in detail.
The organic-inorganic composite material according to the present invention is a material in which inorganic fine particles are dispersed in a resin, and the molded product is applied to an optical element such as an objective lens.

  In the organic-inorganic composite material according to the present invention, in order to ensure transparency and maintain a high light transmittance, as shown in FIG. It is preferable that it is dispersed. However, in reality, as shown in FIG. 1B, the inorganic fine particles are not dispersed only as a single substance, but are also dispersed in the state of an aggregate in which a plurality of simple substances are aggregated. Are present in the resin as dispersed particles.

Therefore, the particle diameter of dispersed particles (including inorganic fine particles and aggregates thereof) is set to D (see FIG. 1B), and the center-to-center distance between any dispersed particle and the adjacent dispersed particle is L. (See FIG. 1 (b)), the range of possible values of the particle diameter D of the dispersed particles and the distance L between the centers of the dispersed particles is a very important factor, and the organic-inorganic composite according to the present invention In the material, the particle size D and the center-to-center distance L satisfy both the following formulas (1) and (2). The organic-inorganic composite material is excellent in transparency and can maintain a high light transmittance when both of these conditions are satisfied.
D ₅₀ ≦ 30 nm (1)
Lp ≦ 30 nm (2)

In the above formula (1), “D ₅₀ ” is a case where the distribution of the particle size D of the dispersed particles and the number of dispersed particles having the particle size D is expressed as a function, as shown in FIG. Furthermore, in the number distribution function, it means the particle diameter D at which the cumulative number of dispersed particles is 50% of the total number.

  As a method for obtaining the number distribution function of dispersed particles, a method of obtaining a section of an organic-inorganic composite material in which dispersed particles are dispersed in a resin and performing image analysis from the transmission electron micrograph, light scattering, etc. The number distribution function of the dispersed particles in the present embodiment is obtained by the X-ray small angle scattering method from the viewpoint of the object to be measured, the range of the particle diameter D, and the like. Specifically, the number distribution function is RINT2500 / PC manufactured by Rigaku Corporation as a measuring device (small-angle wide-angle X-ray diffractometer), and Rigaku Corporation stock as analysis software for X-ray small-angle scattering curves obtained from that device. It is calculated using NANO-solver Ver3.0 manufactured by the company.

The particle diameter D ₅₀ of the dispersed particles satisfies the condition defined in the above formula (1). If the particle diameter D ₅₀ is larger than 30 nm, the degree of light scattering by the dispersed particles in the resin is large. Thus, the object effect of the present invention cannot be realized. In order to increase the light transmittance of the organic-inorganic composite material, the particle diameter D ₅₀ of the dispersed particles is preferably 20 nm or less, and more preferably 10 nm or less.

  Here, when the average primary particle diameter of the inorganic fine particles is defined as Dp, the average primary particle diameter Dp is preferably 1 to 30 nm, more preferably 1 to 20 nm, and 1 to 10 nm or less. It is particularly preferred. The “average primary particle diameter Dp” of the inorganic fine particles indicates the average value of the diameters when the inorganic fine particles (including simple substances constituting the aggregates) are converted into spheres of the same volume. It can be evaluated from a transmission electron micrograph of a section of an organic-inorganic composite material in which fine particles are dispersed in a resin. When the average primary particle diameter Dp is less than 1 nm, it is difficult to disperse the inorganic fine particles in the resin and the desired performance may not be obtained. Therefore, the average primary particle diameter Dp is preferably 1 nm or more. On the other hand, if the average primary particle diameter Dp exceeds 30 nm, the resulting organic-inorganic composite material may become turbid and the transparency may be lowered. Therefore, the average primary particle diameter Dp is preferably 30 nm or less.

The above-mentioned particle diameter D ₅₀ of the dispersed particles preferably satisfies the condition of D ₅₀ ≧ Dp in relation to the average primary particle diameter Dp of the inorganic fine particles. From the viewpoint of manufacturing the organic-inorganic composite material, D ₅₀ More preferably, the condition of ≧ Dp + 1 (nm) is satisfied.

  In the above formula (2), “Lp” represents the distribution of the center-to-center distance L between arbitrary dispersed particles and the frequency of appearance of the center-to-center distance L as a function, as shown in FIG. In this case, the peak center distance L in the frequency distribution function is shown.

  The frequency distribution function of the center-to-center distance L is also obtained by the X-ray small angle scattering method in the same manner as the number distribution function of the dispersed particles. Specifically, as a measuring device (small angle wide angle X-ray diffractometer) RINT2500 / PC manufactured by Rigaku Corporation was calculated using NANO-solver Ver3.0 manufactured by Rigaku Corporation as analysis software for the X-ray small angle scattering curve obtained from the apparatus.

  The center-to-center distance Lp between the dispersed particles satisfies the condition defined in the above formula (2), but if the center-to-center distance Lp exceeds 30 nm, the center-to-center distance L between the dispersed particles becomes too large. As a result, the light transmittance of the organic-inorganic composite material is reduced. The center-to-center distance Lp between the dispersed particles is more preferably 20 nm or less, and further preferably 15 nm or less. However, it is more preferable that the center-to-center distance Lp between dispersed particles satisfies Lp ≧ Dp + 1 (nm) from the viewpoint of manufacturing.

Here, in the organic-inorganic composite material according to the present invention, it is preferable that the center-to-center distance L between the dispersed particles satisfies the condition defined by the following formula (4). If this condition is satisfied, higher light transmission is achieved. Shows the rate.
L ₉₅ ≦ 60 nm (4)

In the above formula (4), “L ₉₅ ” is a cumulative value in the frequency distribution function (see FIG. 2B) of the center-to-center distance L between the arbitrary dispersed particles and the appearance frequency of the center-to-center distance L. It means the center-to-center distance L whose frequency is 95% of the total frequency.

The center-to-center distance L ₉₅ between the dispersed particles satisfies the condition defined in the above formula (4). If the center-to-center distance L ₉₅ between the dispersed particles exceeds 60 nm, the light transmittance of the organic-inorganic composite material is reduced. Decline is likely to occur. The center-to-center distance L ₉₅ between the dispersed particles is more preferably 40 nm or less, and further preferably 30 nm or less.

Furthermore, in the organic-inorganic composite material according to the present invention, when the volume fraction of the inorganic fine particles in the organic-inorganic composite material is defined as Φ, the volume fraction Φ (= (volume occupied by the inorganic fine particles) / (organic It is preferable that the volume of the inorganic composite material)) satisfies the condition defined by the following formula (5). When this condition is satisfied, the rate of change of the refractive index with temperature is small and the transparency is improved. ing.
0.2 ≦ Φ ≦ 0.6 (5)

  The volume fraction Φ means a volume fraction at 23 ° C. unless otherwise specified. The volume fraction Φ of the inorganic fine particles satisfies the condition defined in the above formula (5). However, when the volume fraction Φ is 0.2 or more, the organic inorganic composite material is more effective in practical use. | Dn / dT | is reduced, and the light transmittance is also increased. On the other hand, when the volume fraction Φ of the inorganic fine particles is larger than 0.6, the organic-inorganic composite material becomes brittle and practical use becomes difficult. Accordingly, the volume fraction Φ of the inorganic fine particles is preferably 0.2 to 0.6, more preferably 0.25 to 0.5, and preferably 0.3 to 0.5. Further preferred.

The center distance Lp, L ₉₅ is the formula (2), (4) satisfy the condition for defining the is configured to select an average primary particle diameter Dp and the volume fraction of the inorganic fine particles Φ from the appropriate range Because it is necessary to uniformly disperse the inorganic fine particles in the resin without excessive aggregation, the mixing state of the inorganic fine particles and the resin is controlled to optimally control the torque and mixing time during the mixing. do it.

Next, the type and manufacturing method of the organic-inorganic composite material according to the present invention will be described.
As described above, the organic-inorganic composite material according to the present invention is one in which inorganic fine particles are contained and dispersed in a resin in the form of a simple substance or an aggregate. In the following, first, (1) resin, (2) inorganic The types of fine particles and (3) additives that can be added will be described, and then (4) production method and (5) application examples of the organic-inorganic composite material will be described.

(1) 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. .

(1.1) Thermoplastic resin The thermoplastic resin used in the present invention is an acrylic resin, a cyclic olefin resin, a polycarbonate resin, a polyester resin, a polyether resin, a polyamide resin, or a polyimide from the viewpoint of processability as an optical element. A resin is preferable, and a cyclic olefin is particularly preferable. Specific examples include compounds described in JP-A-2003-73559, and preferred compounds are shown in Table 1 below.

  The above-mentioned thermoplastic resin desirably has a moisture absorption rate of 0.2% or less from the viewpoint of dimensional stability as an optical material. Therefore, polyolefin resin (polyethylene, polypropylene), fluororesin (polytetrafluoroethylene) , Teflon (registered trademark) AF: manufactured by DuPont), cyclic olefin resin (manufactured by Nippon Zeon: ZEONEX, manufactured by Mitsui Chemicals: APEL, manufactured by JSR: Arton, manufactured by Ticona: TOPAS), indene / styrene resin, polycarbonate resin, etc. Preferably used.

(1.2) Curable resin (thermosetting resin or photocurable 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.

(1.2.1) Hydrogenated Epoxy Resin As the curable resin used in the present invention, a hydrogenated epoxy resin can be mentioned, 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 novolak 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 lowered. Can be improved.

(1.2.2) 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.

(1.2.3) 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.

(2) Inorganic fine particles Examples of the inorganic fine particles in the present invention include oxide fine particles, metal salt fine particles, and semiconductor fine particles. Among these, those that do not cause absorption, light emission, fluorescence, etc. in the wavelength region used as an optical element. Can be appropriately selected and 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. 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.

  Among the above inorganic fine particles, since the refractive index of the resin used as the optical material is often about 1.4 to 1.7, oxide fine particles having a refractive index close to this are preferably used in the present invention. It is done. Specific examples include silica (silicon oxide), calcium carbonate, aluminum phosphate, aluminum oxide, magnesium oxide, and aluminum / magnesium oxide. From the standpoint that the refractive index can be arbitrarily adjusted, composite oxide fine particles (a composite oxide in which silicon oxide and one or more metal oxides other than silicon are combined) containing Si and a metal element other than Si are further provided. Preferably used.

  The composition distribution of the composite oxide fine particles preferably used in the present invention is not particularly limited, and silica and other metal oxides may be dispersed substantially uniformly or may form a core shell. In addition, each of silica and other metal oxides constituting the composite oxide preferably used in the present invention may exist as crystals or may be amorphous. In the composite oxide preferably used in the present invention, the content ratio of silica and a metal oxide other than silica can be arbitrarily determined depending on the type of metal oxide and the refractive index value of the inorganic fine particles to be produced.

  When the composite oxide fine particles used in the present invention have a core-shell structure, aluminum oxide, zirconium oxide, titanium oxide, zinc oxide and the like are preferably used as the inner core particles because relatively fine particles can be formed. By using silicon oxide as the shell layer that covers the inner core, the refractive index of the entire metal oxide fine particles can be adjusted to a desired refractive index, and the particle surface can be easily modified with an organic compound, thereby absorbing moisture of the particles. Suppression and good dispersibility in the resin can be achieved. The shell layer thickness is 1 nm or more and 5 nm or less, and preferably 1.5 nm or more and 4 nm or less. If the thickness is less than 1 nm, the inner core particles cannot be completely coated, so that the surface modification of the particles cannot be sufficiently performed. If the thickness exceeds 5 nm, the concentration of the raw material at the time of shell formation becomes high, causing aggregation between the particles. Moreover, since the inter-particle variation of the shell layer thickness is increased, the refractive index distribution is increased, which is not preferable.

  In the present invention, the inorganic fine particles dispersed in the resin may be one kind of inorganic fine particles or a combination of plural kinds of inorganic fine particles as long as the light transmittance is not deteriorated. By using a plurality of types of fine particles having different properties, the required characteristics can be improved more efficiently.

  The shape of the inorganic fine particles is not particularly limited, but spherical fine particles are preferably used. Specifically, the minimum diameter of the particle (minimum value of the distance between the tangents when drawing two tangents in contact with the outer periphery of the fine particle) / maximum diameter (the value in drawing two tangents in contact with the outer periphery of the fine particle The maximum value of the distance between tangents) is preferably 0.5 to 1.0, and more preferably 0.7 to 1.0.

  Further, the particle size distribution is not particularly limited, but in order to achieve the effect of the present invention more efficiently, a particle having a relatively narrow distribution is preferably used rather than a particle having a wide distribution. Used.

  Furthermore, the inorganic fine particles are preferably subjected to a surface treatment. Examples of the surface treatment method for 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 treatment of the inorganic fine particles include silane coupling agents, silicone oil, titanate, aluminate and zirconate coupling agents. These are not particularly limited, but can be appropriately selected depending on the kind of the inorganic fine particles and the resin in which the inorganic fine particles are dispersed. Further, two or more surface treatments may be performed simultaneously or at different times.

  Examples of silane-based surface treatment agents include vinylsilazane trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, and hexamethyldisilazane. For covering, hexamethyldisilazane or the like is preferably used.

Examples of silicone oil processing agents include straight silicone oils 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, Methacryl-modified silicone oil, mercapto-modified silicone oil, phenol-modified silicone oil, one-end reactive modified silicone oil, heterogeneous 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 special modified silicone oil, higher alkoxy modified silicone oil, higher fat It is possible to use the content-modified silicone oil and modified silicone oil and fluorine-modified silicone oil.

  These treatment agents may be used after 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. When surface modification of 100 nm or less is performed, 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. In addition, the properties of the surface-modified fine particles obtained may vary depending on the surface modifier used, and the affinity with the resin used in obtaining the organic-inorganic composite material can be achieved by selecting the surface modifier. The ratio of the surface modification is not particularly limited, but the ratio of the surface modifier is preferably in the range of 10 to 99% by mass with respect to the inorganic fine particles after the surface modification, and is preferably 30 to 98% by mass. A range is more preferable.

(3) Additives In the manufacturing process and molding process of the organic-inorganic composite material, various additives (hereinafter, also referred to as compounding agents) can be added as necessary. The additives are not particularly limited, but mainly include plasticizers, antioxidants, light stabilizers, etc. Other than these, heat stabilizers, weather stabilizers, ultraviolet absorbers, near infrared absorption Stabilizers such as agents; resin modifiers such as lubricants; anti-clouding agents such as soft polymers and alcoholic compounds; colorants such as dyes and pigments; antistatic agents, flame retardants and fillers. These compounding agents can be used alone or in combination of two or more thereof, and the compounding amount is appropriately selected within a range not impairing the effects described in the present invention. In particular, the polymer preferably contains at least a plasticizer or an antioxidant.

(3.1) Plasticizer The plasticizer is not particularly limited, but is a phosphate ester plasticizer, a phthalate ester plasticizer, a trimellitic ester plasticizer, a pyromellitic acid plasticizer, Examples include glycolate plasticizers, citrate ester plasticizers, and polyester plasticizers.

  As the phosphate ester plasticizer, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc., phthalate ester plasticizer, 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 triethyl trimellitate, tetrabutyl pyromellitate, tetra Examples of glycolate plasticizers such as phenyl pyromellitate and tetraethyl pyromellitate include triacetin, tributyrin, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate, and citrate plasticizers. Examples thereof include triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, and acetyl tri-n- (2-ethylhexyl) citrate.

(3.2) Antioxidants Examples of antioxidants include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. Among them, phenolic antioxidants, particularly alkyl-substituted phenolic compounds. Antioxidants are preferred. 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. Further, the 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 with respect to 100 parts by mass of the resin. The range is preferably 0.001 to 10 parts by mass, and more preferably 0.01 to 1 part by mass.

  A conventionally well-known thing is applicable as a phenolic antioxidant, 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-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di) t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenylpropionate)) methane [i.e. pentaerythrimethyl-tetrakis ( 3- (3,5-di-t-butyl-4-hydroxyphenylpropionate))], triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate) and the like Alkyl substituted phenol compounds; 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1,3,5-triazine, 4-bisoctylthio-1,3 5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3,5-triazine, etc. Triazine group-containing phenol compounds, and the like.

  Phosphorous antioxidants include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t -Butylphenyl) phosphite, monophosphites such as 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide 4,4'-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C15) And diphosphite compounds such as) phosphite). 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.

  Sulfur-based antioxidants include dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3-thiodipropionate Pentaerythritol-tetrakis- (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane and the like. .

(3.3) Light Stabilizer Examples of the light stabilizer include a benzophenone light stabilizer, a benzotriazole light stabilizer, a hindered amine light stabilizer, etc. From the viewpoint of properties and the like, it is preferable to use a hindered amine light-resistant stabilizer. Among hindered amine light-resistant stabilizers (hereinafter referred to as HALS), those having a molecular weight Mn in terms of polystyrene by liquid chromatography using tetrahydrofuran as a solvent are preferably 1,000 to 10,000, and preferably 2,000 to 5,000. Some are more preferred, with 2,800-3,800 being particularly preferred. When Mn is too small, when HALS is blended by heating and kneading into a block copolymer, a predetermined amount cannot be blended due to volatilization, or foaming or silver streak occurs during heat melting molding such as injection molding. This is because there arises a problem that the stability is lowered.

  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. For this reason, when Mn is too large, the dispersibility to a block copolymer will fall, the transparency of a lens will fall, and the effect of light resistance improvement will reduce. Therefore, by setting the HALS Mn within the above-described range, a lens excellent in processing stability, low gas generation property, and transparency can be obtained.

  The HALS mentioned above includes N, N ′, N ″, N ′ ″-tetrakis- [4,6-bis- {butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl]. ) Amino} -triazin-2-yl] -4,7-diazadecane-1,10-diamine, dibutylamine and 1,3,5-triazine, N, N'-bis (2,2,6,6- Polycondensate with tetramethyl-4-piperidyl) butylamine, poly [{(1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2, 2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], 1,6-hexanediamine-N, N′- Bis (2,2,6,6-tetramethyl-4-pipe Di) 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 piperidine rings are bonded via a lyazine skeleton. Molecular weight HALS; polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, 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-tetraoxaspiro [5,5] undecane S Piperidine ring, such as Le compound is bound high molecular weight HALS, and the like via an ester bond.

  Among these, a polycondensate 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}], dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, etc. Is preferably in the range of 2,000 to 5,000.

(3.4) Blending amount etc. The blending amount of the various additives described above with respect to the organic-inorganic composite material is preferably in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the polymer, and 0.02 More preferably, it is the range of -15 mass parts, and it is especially preferable that it is 0.05-10 mass parts. This is because if the addition amount is too small, the effect of improving the light resistance cannot be sufficiently obtained. Therefore, when used as an optical element such as a lens, coloring occurs due to irradiation with a laser or the like, and the HALS content is too large. This is because a part of the gas is generated as a gas and the dispersibility in the resin is lowered, so that the transparency of the lens is lowered.

  Moreover, it is preferable to mix | blend the compound whose lowest glass transition temperature is 30 degrees C or less in addition to an organic inorganic composite material. This is because white turbidity in a high temperature and high humidity environment for a long time can be prevented without degrading various properties such as transparency, heat resistance and mechanical strength.

(4) Manufacturing Method The organic-inorganic composite material according to the present invention is composed of a resin and inorganic fine particles as described above, but the manufacturing method is not particularly limited.
When a thermoplastic resin is used as the resin, a method of forming a composite by polymerizing a thermoplastic resin in the presence of inorganic fine particles, a method of forming and combining inorganic fine particles in the presence of a thermoplastic resin, A method of forming a dispersion in a liquid that becomes a solvent for a plastic resin and then compounding by removing the solvent, preparing inorganic fine particles and a thermoplastic resin separately, melt-kneading, melt-kneading in a state containing a solvent, etc. It can be produced by any method such as a method of compounding with the above. Various additives may be added at any step of the compounding process, but the addition timing that does not hinder the compounding can be selected.

  Among these, the method of preparing the inorganic fine particles and the thermoplastic resin separately and combining them by melt-kneading is preferably used because it is simple and can suppress the manufacturing cost. As an apparatus which can be used for melt kneading, a closed kneading apparatus or a batch kneading apparatus such as a lab plast mill, a Brabender, a Banbury mixer, a kneader, a roll, and the like can be given. Moreover, it can also manufacture using a continuous melt-kneading apparatus like a single screw extruder, a twin screw extruder, etc.

  When melt kneading is used in the method for producing an organic-inorganic composite material, the thermoplastic resin and the inorganic fine particles may be added and kneaded all at once, or may be added in stages and kneaded. 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. In addition, after kneading in advance, when components other than thermoplastic resin that have not been added in advance are added and further melt-kneaded, these may be added all at once and kneaded, or added in stages. And may be kneaded. The method of adding in a divided manner or the method of adding one component in several batches can be adopted, the method of adding one component at a time and the method of adding different components in stages can also be adopted, both of which are combined The method is fine.

  In the case of compounding by melt kneading, the inorganic fine particles can be added in a powder or agglomerated 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 perform devolatilization after kneading | mixing.

  When adding in the state disperse | distributed in a liquid, it is preferable to disperse | distribute aggregated particles to a primary particle beforehand, 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.

  In the organic-inorganic composite material of the present invention, when a curable resin is used as the resin, a monomer of the curable resin, a curing agent, a curing accelerator, and various additives are mixed with inorganic fine particles appropriately subjected to surface treatment, ultraviolet rays and It can be obtained by curing by either electron beam irradiation or heat treatment.

  The degree of mixing of the resin and the inorganic fine particles in the organic-inorganic composite material is not particularly limited, but it is desirable that the resin is uniformly mixed in order to achieve the effect of the present invention more efficiently. When the degree of mixing is insufficient, there is a concern that the particle size distribution of the inorganic fine particles in the organic-inorganic composite material may be difficult to satisfy the conditions defined in the present invention. Since the particle size distribution of the inorganic fine particles in the resin is greatly influenced by the production method thereof, it is important to select an optimal method in consideration of the characteristics of the resin and the inorganic fine particles used.

  Various molding materials can be obtained by molding the organic-inorganic composite material as described above, but the molding method is not particularly limited. When a thermoplastic resin is used as the resin, a melt molding method is preferably used in order to obtain a molded product having excellent characteristics such as low birefringence, mechanical strength, and dimensional accuracy, and a commercially available press molding is used as the melt molding method. , Commercially available extrusion molding, and commercially available injection molding. Among these, injection molding is preferably used from the viewpoint of moldability and productivity.

  On the other hand, when a curable resin is used as the resin, a mixture of a resin composition such as a curable resin monomer and a curing agent and inorganic fine particles is used. The resin composition is filled into a predetermined shape mold or the like, or applied onto a substrate and then cured by irradiation with ultraviolet rays and an electron beam. On the other hand, when the curable resin is a thermosetting resin, It can be cured by compression molding, transfer molding, injection molding or the like.

(5) Application Example The molded product of the organic-inorganic composite material can be applied to an optical element or the like. The molded product can be used in various forms such as spherical, rod-shaped, plate-shaped, cylindrical, cylindrical, tube-shaped, fibrous, film or sheet-shaped, and has low birefringence, transparency, machine Since it is excellent in strength, heat resistance and low water absorption, application to various optical elements is suitable.

  As a specific application 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 or a CD-ROM , WORM (recordable optical disc), MO (rewritable optical disc; magneto-optical disc), MD (mini disc), DVD (digital video disc) and other optical disc pickup lens; laser beam printer fθ lens, sensor lens And a laser scanning system lens such as a camera finder system prism lens.

  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 the above-mentioned molded products, it is preferable to be used as an optical element such as a pickup lens that requires low birefringence or a laser scanning lens.

  Hereinafter, an optical pickup device 1 using an optical element formed of the organic-inorganic composite material will be described with reference to FIG.

FIG. 3 is a schematic diagram showing the internal structure of the optical pickup device 1.
As shown in FIG. 3, the optical pickup device 1 in this embodiment includes a semiconductor laser oscillator 2 that is a light source. On the optical axis of the blue light emitted from the semiconductor laser oscillator 2, a collimator 3, a beam splitter 4, a quarter wavelength plate 5, a diaphragm 6, and an objective lens 7 are arranged in a direction away from the semiconductor laser oscillator 2. Are sequentially arranged.

  In addition, a sensor lens group 8 and a sensor 9 including two sets of lenses are sequentially disposed in a direction close to the beam splitter 4 and in a direction perpendicular to the optical axis of the blue light described above.

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

Next, the operation of the optical pickup device 1 will be described.
The optical pickup device 1 in the present embodiment emits blue light from the semiconductor laser oscillator 2 at the time of recording information on the optical disc D or at the time of reproducing information recorded on the optical disc D. As shown in FIG. 3, the emitted blue light becomes a light ray L1, is collimated to infinite parallel light through the collimator 3, and then is transmitted through the beam splitter 4 to pass through the quarter wavelength plate 5. To Penetrate. Further, after passing through the diaphragm 6 and the objective lens 7, a condensed spot is formed on the information recording surface D ₂ via the protective substrate D ₁ of the optical disc D.

The light that forms the condensed spot is modulated by the information pits on the information recording surface D ₂ of the optical disc D and reflected by the information recording surface D ₂ . Then, the reflected light is sequentially transmitted through the objective lens 7 and the diaphragm 6, the polarization direction is changed by the quarter wavelength plate 5, and the reflected light is reflected by the beam splitter 4. After that, astigmatism is given through the sensor lens group 8, received by the sensor 9, and finally converted into an electric signal by being photoelectrically converted by the sensor 9.
Thereafter, such an operation is repeatedly performed, and the operation of recording information on the optical disc D and the operation of reproducing information recorded on the optical disc D are completed.

Incidentally, the magnitude of the thickness and the information pits of the protective substrate D ₁ of the optical disc D, also the numerical aperture NA required for the objective lens 7 different. In the present embodiment, the optical disc D is a high density, and its numerical aperture is set to 0.85.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[Example 1]
(1) Preparation and preparation of inorganic fine particles (1.1) Preparation of inorganic fine particles A Silica (manufactured by Nippon Aerosil Co., Ltd .: RX300, average primary particle diameter 7 nm) was prepared as “inorganic fine particles A”.
(1.2) Preparation of inorganic fine particles B Silica (manufactured by Nippon Aerosil Co., Ltd .: RX200, average primary particle size 12 nm) was prepared as “inorganic fine particles B”.

(1.3) Preparation of inorganic fine particles C A suspension prepared by adding 10 g of aluminum oxide (Aluminium Oxide C manufactured by Nippon Aerosil Co., Ltd.) to a mixed solution of pure water 160 cc, ethanol 560 cc, and ammonia water (25%) 30 cc, Dispersion was performed using an ultra apex mill (Sakai Industry Co., Ltd.) to obtain a dispersion of alumina particles. Next, while stirring this dispersion, a mixed solution of 50 cc of tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical), 16 cc of water, and 56 cc of ethanol was added dropwise to the dispersion over 8 hours. When the dispersion was further stirred for 1 hour, the pH of the dispersion was raised to 10.4 using aqueous ammonia, and the dispersion was stirred at room temperature for 15 hours. Thereafter, the particles were separated from the dispersion liquid using centrifugal separation, and the liquid was heated at 190 ° C. for 5 hours and dried to obtain “inorganic fine particles C” in the form of white powder. When the average primary particle diameter Dp of the obtained inorganic fine particles C was evaluated with a transmission electron microscope, it was Dp = 17 nm.

(1.4) Preparation of inorganic fine particles D 100 g of zirconia oxide 10 wt% dispersion (Sumitomo Osaka Cement Co., Ltd.) was diluted with 135 cc of pure water, and 3.7 g of 3-aminopropyltrimethoxysilane was added to the dispersion. Was slowly added dropwise at room temperature, and the solution was stirred at 60 ° C. for 10 hours. The solution was cooled to room temperature, and 680 cc of ethanol and 230 cc of aqueous ammonia (28% Kanto Chemical) were added to the solution. Thereafter, while stirring the solution, a mixed solution of 15 g of tetraethoxysilane (Shin-Etsu Chemical), 200 cc of ethanol and 100 cc of water was dropped into the solution over 6 hours. After completion of the dropwise addition, the solution was further stirred for 12 hours. After completion of the stirring, the particles were centrifuged from the solution, and the particles were washed with ethanol. The washed particles were dried at 90 ° C. to remove ethanol, and then the particles were fired at 450 ° C. to obtain “inorganic fine particles D” in the form of white powder. When the average primary particle diameter Dp of the obtained inorganic fine particles D was evaluated with a transmission electron microscope, it was Dp = 7 nm.

(2) Preparation of Sample (2.1) Preparation of 1-4 Using the resin of Chemical Formula 2 listed in Table 1 as the thermoplastic resin and the inorganic fine particles A as the inorganic fine particles, “Samples 1 to 4” were prepared by melt kneading. Produced. Specifically, as a kneading apparatus, a lab plast mill μ manufactured by Toyo Seiki Seisakusho is used, a segment mixer KF6 is mounted, the thermoplastic resin and the inorganic fine particles A are charged into the mixer, and the kneading time is 1 to 30 minutes. The samples 1 to 4 were prepared by kneading with appropriate changes. During the kneading, N ₂ gas was introduced into the system from the sample inlet to suppress air contamination. The volume fraction Φ of the inorganic fine particles A with respect to the thermoplastic resin was set to be Φ = 0.3 for the samples 1 to 3 and Φ = 0.2 for the sample 4.

(2.2) Preparation of Samples 5 to 8 The thermoplastic resin and the kneading apparatus are the same as those described in the item (2.1) above, and the inorganic fine particles A are changed to the inorganic fine particles B. The thermoplastic resin and the inorganic fine particles B were kneaded while changing the kneading time within the same range as described above to produce “Samples 5 to 8”. At this time, the volume fraction Φ of the inorganic fine particles B with respect to the thermoplastic resin is Φ = 0.3 for the sample 5, Φ = 0.2 for the samples 6 and 7, and Φ = 0.4 for the sample 8. It was made to become.

(2.3) Preparation of Samples 9 to 11 The thermoplastic resin and the kneading apparatus are the same as those described in the item (2.1) above, and the inorganic fine particles A are changed to the inorganic fine particles C. The thermoplastic resin and the inorganic fine particles C were kneaded while changing the kneading time within the same range as described above to produce “Samples 9 to 11”. At this time, the volume fraction Φ of the inorganic fine particles C with respect to the thermoplastic resin was all set to Φ = 0.3.

(2.4) Preparation of Samples 12 to 14 The thermoplastic resin and the kneading apparatus are the same as those described in the item (2.1) above, and the inorganic fine particles A are changed to the inorganic fine particles D. The thermoplastic resin and the inorganic fine particles D were kneaded while changing the kneading time within the same range as described above to produce “Samples 12 to 14”. At this time, the volume fraction Φ of the inorganic fine particles C with respect to the thermoplastic resin was all set to Φ = 0.3.

(3) Evaluation of sample (3.1) Measurement of particle size distribution and center-to-center distance distribution of inorganic fine particles X-ray small angle scattering measurement was performed using a small angle wide angle X-ray diffractometer (RINT2500 / PC, manufactured by Rigaku Corporation). Then, the particle size distribution and the center-to-center distance distribution of the inorganic fine particles A, B, C, and D in the thermoplastic resin in each of the samples 1 to 14 were obtained. The measurement was performed by the transmission method under the following measurement conditions. At this time, the thickness of each sample 1-14 was adjusted to 1 / μ (μ is the mass absorption coefficient of each sample 1-14).

Target: Copper Output: 40kV-200mA
1st slit: 0.04mm
2nd slit: 0.03 mm
Light receiving slit: 0.1 mm
Scattering slit: 0.2 mm
Measurement method: 2θ FT scan method Measurement range: 0.1 to 6 °
Sampling: 0.04 °
Counting time: 30 seconds

  Then, based on the obtained scattering pattern, each sample 1-14 was analyzed using the analysis software (Rigaku Denki Co., Ltd. product: NANO-solver Ver3.0). Here, the blank data necessary for the analysis was obtained by setting each sample for measurement 1 to 14 on the incident side of the light receiving slit box and measuring under the same conditions.

In the analysis, blank data was removed and slit correction was performed, and fitting was performed to determine the particle size distribution and the center-to-center distance distribution of the dispersed particles of the inorganic fine particles A, B, C, and D. A numerical value of D ₅₀ was calculated based on the obtained particle size distribution, and numerical values of Lp and L ₉₅ were calculated based on the obtained center-to-center distance distribution. These calculation results are shown in Table 2 below.

(3.2) Measurement of light transmittance After each sample 1-14 was heated and melted, each sample 1-14 was molded into a plate having a thickness of 3 mm. About each of the obtained plate-shaped samples 1-14, the transmittance | permeability of the thickness direction in wavelength 588nm was measured with the spectrophotometer (Shimadzu Corporation make: UV-3150). The measurement results are shown in Table 2 below.

(3.3) Calculation of rate of change of dn / dT Using an automatic refractometer (Kalnew Optical Industry Co., Ltd .: KPR-200), the temperature of each sample 1-14 was changed from 10 ° C. to 60 ° C., and the refraction at a wavelength of 588 nm. The rate was measured and dn / dT in each sample 1-14 was calculated. In addition, the dn / dT in the thermoplastic resin is calculated by the same method for the thermoplastic resin to which none of the inorganic fine particles A, B, C, and D are added (the resin of the chemical formula 2 described in Table 1). did. Based on these calculation results, the change rate of dn / dT of each sample 1-14 was calculated by the following formula. The calculation results are shown in Table 2 below.

  dn / dT change rate = (dn / dT in the thermoplastic resin−dn / dT in each sample 1 to 14) / (dn / dT in the thermoplastic resin) × 100

(4) Summary As shown in Table 2, Samples 1, 2, 5 to 10, 12, and 13 that satisfy the conditions defined by the above formulas (1) and (2) are Samples 3, 4, and 4 that do not satisfy the conditions. 11 and 14, the light transmittance is high and the dn / dT change rate is large. Therefore, it is proved that the temperature dependence of the refractive index is small and the transparency is high and the optically excellent organic-inorganic composite material. did.

[Example 2]
(1) Preparation and Preparation of Inorganic Fine Particles “Inorganic fine particles A, B, C, D” were prepared and prepared in the same manner as in Example 1.

(2) Preparation of sample (2.1) Preparation of samples 15-18 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexene carboxylate as a curable resin (Celoxide 2021 manufactured by Daicel Chemical Industries, Ltd.) 100 parts by mass, 100 parts by mass of methylhexahydrophthalic anhydride as a curing agent (Epiclon B-650 manufactured by Dainippon Ink & Chemicals, Inc.), and 2-ethyl-4-methylimidazole (Shikoku Chemical Industries, Ltd.) as a curing accelerator 2E4MZ (made by company) and phenolic antioxidant (tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenylpropionate) methane) as a stabilizer. 1 part by mass and 0.1 parts by mass of a phosphorus stabilizer (2,2′-methylenebis (4,6di-tert-butylphenyl) -2-ethylhexyl phosphite); Relative mixture is mixed with inorganic fine particles A, and dispersed using a tabletop 3-roll mill (Co. Irie Shokai Ltd. RM-1).

  The obtained dispersion is defoamed with an automatic revolution mixer (Shinky Awatori Nertaro AR-100), and the defoamed dispersion is poured into a mold at 100 ° C. for 3 hours. Curing was performed in an oven at 140 ° C. for 3 hours to obtain a colorless and transparent cured product. At this time, the number of treatments by the roll mill was changed between 1 and 10 to produce “Samples 15 to 18” having different degrees of dispersion. The volume fraction Φ of the inorganic fine particles A with respect to the curable resin was set to be Φ = 0.3 for the samples 15 to 17 and Φ = 0.2 for the sample 18.

(2.2) Production of Samples 19 to 22 “Samples 19 to 22” were produced in the same manner as in (2.1) above, except that the inorganic fine particles A were changed to the inorganic fine particles B. At this time, the volume fraction Φ of the inorganic fine particles B with respect to the curable resin, Φ = 0.3 for the sample 19, Φ = 0.2 for the sample 20, and Φ = 0.4 for the sample 21, For Sample 22, Φ = 0.5.

(2.3) Production of Samples 23 to 25 “Samples 23 to 25” were produced in the same manner as in (2.1) above, except that the inorganic fine particles A were changed to the inorganic fine particles C. At this time, all the volume fractions Φ of the inorganic fine particles C with respect to the curable resin were set to Φ = 0.4.

(2.4) Preparation of Samples 26 to 28 “Samples 26 to 28” were prepared in the same manner as in (2.1) above, except that the inorganic fine particles A were changed to the inorganic fine particles D. At this time, all the volume fractions Φ of the inorganic fine particles D with respect to the curable resin were set to Φ = 0.3.

(3) Evaluation of Samples Samples 15 to 28 were evaluated in the same manner as in Example 1, and the evaluation results are shown in Table 3 below.
The light transmittance was measured by cutting each sample 15 to 28 on a plate having a thickness of 3 mm. About the dn / dT change rate, it was set as the dn / dT change rate with respect to the hardened | cured material hardened without adding any of inorganic fine particles A, B, C, and D.

(4) Summary As shown in Table 3, the samples 15, 16, 19 to 24, 26, 27 satisfying the conditions defined by the above formulas (1) and (2) are the samples 17, 18, 19 that do not satisfy the conditions. 25 and 28 have a high light transmittance and a large dn / dT change rate, so that it was found to be an optically superior organic-inorganic composite material with a low temperature dependence of refractive index and high transparency. did.

(A) It is a schematic diagram which shows the state which the inorganic fine particle disperse | distributed in resin alone, (b) It is a schematic diagram which shows the state in which the inorganic fine particle was disperse | distributed in resin with the simple substance and its aggregate. (A) It is the schematic which shows the number distribution function of the particle size D of a dispersed particle, and the number of the dispersed particles which have the particle size D, (b) The distance L between centers of arbitrary dispersed particles, and the distance between the centers. It is the schematic which shows the frequency distribution function with the appearance frequency of L. 2 is a schematic diagram showing an internal structure of the optical pickup device 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical pick-up apparatus 2 Semiconductor laser oscillator 3 Collimator 4 Beam splitter 5 1/4 wavelength plate 6 Aperture 7 Objective lens (optical element)
8 Sensor lens group 9 Sensor 10 Two-dimensional actuator D Optical disk D ₁ Protection substrate D ₂ Information recording surface

Claims (6)

An organic-inorganic composite material in which inorganic fine particles are dispersed in a resin,
The inorganic fine particles are dispersed in the resin in a state of primary particles or in a state where a plurality of primary particles are aggregated, and the particle size of these dispersed particles is D, and the dispersed particles adjacent to any of the dispersed particles. An organic-inorganic composite material characterized in that when the center-to-center distance is defined as L, the particle diameter D and the center-to-center distance L satisfy both conditions defined by the following formulas (1) and (2).
D ₅₀ ≦ 30 nm (1)
Lp ≦ 30 nm (2)
(In the above formula (1), “D ₅₀ ” means the particle size D in which the cumulative number is 50% of the total number in the number distribution function of the dispersed particles. In the above formula (2), “Lp”. Means the center distance L of the peak in the frequency distribution function of the center distance L.) The organic-inorganic composite material according to claim 1,
An organic-inorganic composite material, wherein the center-to-center distance L satisfies a condition defined by the following formula (3).
Lp ≦ 20 nm (3) The organic-inorganic composite material according to claim 1 or 2,
An organic-inorganic composite material, wherein the center-to-center distance L satisfies a condition defined by the following formula (4).
L ₉₅ ≦ 60 nm (4)
(In the above formula (4), “L ₉₅ ” means the center distance L at which the cumulative frequency is 95% of the total frequency in the frequency distribution function of the center distance L.) In the organic-inorganic composite material according to any one of claims 1 to 3,
An organic-inorganic composite material, wherein the volume fraction of the inorganic fine particles in the organic-inorganic composite material is defined as Φ, and the volume fraction Φ satisfies a condition defined by the following formula (5).
0.2 ≦ Φ ≦ 0.6 (5) In the organic-inorganic composite material according to any one of claims 1 to 4,
An organic-inorganic composite material, wherein the inorganic fine particle is a composite oxide in which a silicon oxide and one or more kinds of metal oxides other than silicon are combined.   An optical element formed using the organic-inorganic composite material according to claim 1.

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