JP2007217659A - Resin composition and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition having small rate of change of refractive index by temperature and excellent in transparency. <P>SOLUTION: An objective lens 7 as optical element in the present invention is composed of the resin composition in which inorganic microparticles are dispersed into a resin. In the resin composition, when a correlation distance of two phase structure composed of an inorganic microparticle phase and a resin phase is defined as A, the correlation distance A satisfies a condition specified by formula (1): 1 nm≤A≤20 nm and when volume fraction of the inorganic microparticles occupied in the resin composition is defined as Φ, the volume fraction Φ satisfies a condition specified by formula (2): 0.2≤Φ≤0.6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin composition and an optical element, and in particular, a resin that is suitably used as a lens, filter, grating, optical fiber, flat optical waveguide, etc., has a small refractive index change rate due to temperature, and is excellent in transparency. The present invention relates to a composition and an optical element using the composition.

  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.
JP 2002-105131 A (page 4) JP 2002-207101 A (Claims)

  However, in the case of the above-described optical plastic material in which fine particles are dispersed, in order to reduce the host material (dn / dT) by 50%, it is necessary to mix 40% by mass or more of inorganic fine particles, etc. (dn In order to reduce / dT), it is necessary to mix a large amount of inorganic fine particles. Thus, when the amount of inorganic fine particles added is large, the influence of light scattering by the inorganic fine particles cannot be ignored, and the dispersion state of the inorganic fine particles in the resin is expected to greatly affect the light transmittance. In particular, when it is used as an optical element of an optical pickup device using a blue-violet laser light source, which is being put into practical use in recent years, it is expected that the influence of light scattering will be greater. At present, no technology is disclosed for controlling the dispersion state in the resin so that the obtained light transmittance can be obtained.

  The present invention has been made in view of the above points, and an object thereof is to provide a resin composition and an optical element that are excellent in transparency and have a small refractive index change rate due to temperature.

In order to solve the above problem, the invention according to claim 1 is:
In a resin composition in which inorganic fine particles are dispersed in a resin,
When the correlation distance of the two-phase structure consisting of the inorganic fine particle phase and the resin phase is A, the inorganic fine particle satisfies the condition defined by the following formula (1) and occupies the resin composition. When the volume fraction of Φ is Φ, the volume fraction Φ satisfies the condition defined by the following equation (2).
1 nm ≦ A ≦ 20 nm (1)
0.2 ≦ Φ ≦ 0.6 (2)

The invention described in claim 2
The resin composition according to claim 1,
When the mean square of the dielectric constant fluctuation of the resin composition is B, the correlation distance A and the mean square B of the dielectric constant fluctuation satisfy the condition defined by the following formula (3). .
A ³ × B ≦ 5.0 (3)

The invention according to claim 3
In the resin composition according to claim 1 or 2,
The inorganic fine particle is a complex oxide in which a silicon oxide and one or more kinds of metal oxides other than silicon are complexed.

The invention according to claim 4
It is the optical element characterized by shape | molding using the resin composition as described in any one of Claims 1-3.

  ADVANTAGE OF THE INVENTION According to this invention, the change rate of the refractive index with temperature is small, and the resin composition and optical element which were excellent in transparency can be provided (refer the following Example).

Hereinafter, the best mode for carrying out the present invention will be described in detail.
The resin composition according to the present invention is one 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.

  The light transmittance of the resin composition in which the inorganic fine particles are dispersed in the resin greatly depends on the dispersion state of the inorganic fine particles. In order to realize a high light transmittance, it is easily predicted that it is necessary to disperse the inorganic fine particles in the state of primary particles in the resin, depending on the particle size of the inorganic fine particles. However, it is difficult to uniformly disperse all the inorganic fine particles having a particle diameter of several nm to several tens of nm so as not to greatly reduce the light transmittance in a primary particle state without aggregation.

  In general, it is said that light scattering by particles having a particle size smaller than the wavelength can be explained by Rayleigh scattering theory. However, the Rayleigh scattering theory is a theory that can be applied when the scattering points are sufficiently distant from each other and the scattered light does not interfere with each other. In order to reduce the rate of change in refractive index due to temperature, as in the resin composition of the present invention. It is considered that the method cannot be applied when the amount of inorganic fine particles added is large.

Thus, as a result of intensive studies, the present inventors have determined that when the correlation distance of the two-phase structure composed of the inorganic fine particle phase and the resin phase is A in the resin composition in which the inorganic fine particles are dispersed in the resin, When the correlation distance A satisfies the condition defined by the following formula (1) and the volume fraction of the inorganic fine particles in the resin composition is Φ, the volume fraction Φ is defined by the following formula (2). When satisfying the above conditions, it has been found that a resin composition having excellent transparency can be obtained, and the present invention has been achieved.
1 nm ≦ A ≦ 20 nm (1)
0.2 ≦ Φ ≦ 0.6 (2)

  Here, the correlation distance A of the two-phase structure means that the inorganic fine particle phase and the resin phase are mixed and mixed as shown in FIG. 1 (a), or in the resin phase as shown in FIG. 1 (b). In a system that forms a two-phase structure composed of an inorganic fine particle phase and a resin phase in which the inorganic fine particle phase is dispersed in the region, attention is paid to a certain coordinate position r, and r away from the position by R. When the probability γ (R) in which the same phase exists is approximated by γ (R) = exp (−R / A), it means the distance A at which the probability γ becomes 1 / e.

The correlation distance A in the present embodiment is defined as that obtained by the X-ray small angle scattering method from the size of the inorganic fine particles contained in the measurement object.
Specifically, for the correlation distance A, RINT2500 / PC manufactured by Rigaku Corporation is used as a measuring device (small-angle wide-angle X-ray diffractometer), and Rigaku Electric Co., Ltd. is used as analysis software for X-ray small-angle scattering curves obtained from that device It is defined as a distance R that is a correlation function γ (R) = 1 / e calculated by performing model-free analysis using a company-made NANO-solver Ver3.0 and applying a two-phase separation Debye model.

  In the condition defined by the above formula (1), the correlation distance A is limited to 20 nm or less because, when the correlation distance A is greater than 20 nm, the light transmittance required for practical use cannot be realized. is there. On the other hand, the reason why the correlation distance A is limited to 1 nm or more is that when the correlation distance A is smaller than 1 nm, it is not practical because inorganic fine particles having a very small primary particle size need to be dispersed at a high concentration.

  In the present invention, the volume fraction Φ of the inorganic fine particles in the resin composition is defined by Φ = (volume occupied by the inorganic fine particles) / (volume of the resin composition).

  The volume fraction Φ means a volume fraction at 23 ° C. unless otherwise specified. It is preferable that the volume fraction Φ of the inorganic fine particles satisfies the condition defined by the formula (2). When the volume fraction Φ is 0.2 or more, | dn / dT | A reduction effect can be obtained and the light transmittance tends to increase. On the other hand, when the volume fraction Φ of the inorganic fine particles is larger than 0.6, the melt viscosity of the resin composition becomes high and uniform dispersion becomes difficult, and the resin composition becomes brittle and practical use becomes difficult. Therefore, the volume fraction Φ of the inorganic fine particles is preferably 0.2 to 0.6, and more preferably 0.25 to 0.5 in order to obtain an effective | dn / dT | reduction effect. Is more preferable, and it is more preferable that it is 0.3-0.5.

Further, as a result of intensive studies, the present inventors have determined that when the square average of the dielectric constant fluctuation of the resin composition is B, the correlation distance A and the square average of the dielectric constant fluctuation B are expressed by the following formula (3). It has been found that a resin composition having further excellent transparency can be obtained when the conditions specified in 1) are satisfied.
A ³ × B ≦ 5.0 (3)

Here, the mean square B of the dielectric constant fluctuation of the resin composition is the average of the refractive index of the resin in which the inorganic fine particles are not dispersed is n ₀ , the refractive index of the inorganic fine particles is n ₁ , and the resin composition obtained by mixing them. Is defined by the following equation (4) using the volume fraction Φ as a refractive index of n ₂ .
B = (n ₀ ² −n ₂ ² ) ² · (1−Φ) + (n ₁ ² −n ₂ ² ) ² · Φ (4)

It has been found that the smaller the value of A ³ × B calculated from the correlation distance A and the root mean square B of the dielectric constant fluctuation, the higher the light transmittance of the resulting resin composition, and the resin composition of the present invention has the formula If (3) is satisfied, the light transmittance exceeds 75%, preferably 3.0 or less, more preferably because the light transmittance exceeds 80%, and if 1.5 or less, the light transmittance is 85%. Since it exceeds, it is further preferable.

Next, the type and manufacturing method of the resin composition according to the present invention will be described.
As described above, the resin composition according to the present invention is obtained by dispersing inorganic fine particles in a resin. In the following, first, (1) a resin, (2) inorganic fine particles, and (3) an additive that can be added. Each of these types will be described, and then (4) production method and (5) application example of the resin composition will be respectively 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 (MgAl2 O4), 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 viewpoint that the refractive index can be arbitrarily adjusted, composite oxide fine particles containing Si and a metal element other than Si are more 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 host material 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 average primary particle diameter of the inorganic fine particles is preferably 1 to 30 nm, more preferably 1 to 20 nm, and particularly preferably 1 to 10 nm. The average primary particle diameter of the inorganic fine particles indicates an average value of the diameters when the inorganic fine particles are converted into spheres having the same volume, and this value can be evaluated from a transmission electron micrograph.

  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 production process and molding process of the resin composition, 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) Compounding amount etc. The compounding amount of the various additives described above with respect to the resin composition is preferably in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the polymer. The range is more preferably 15 parts by mass, and particularly preferably 0.05 to 10 parts by mass. 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.

  In addition to the resin composition, a compound having the lowest glass transition temperature of 30 ° C. or less is preferably blended. 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 Although the resin composition which concerns on this invention consists of resin and an inorganic fine particle as mentioned above, the manufacturing method is not specifically 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.

  In the method for producing a resin composition, when melt kneading is used, the thermoplastic resin and the inorganic fine particles may be added and kneaded in a lump, or may be divided and added in stages. In this case, in a melt-kneading apparatus such as an extruder, it is possible to add the components to be added step by step from the middle of the cylinder. 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 as a powder, or can be added in a dispersed state in the liquid, but the inorganic fine particles can be added in advance at a predetermined mixing ratio. A method is preferred in which a master batch in which fine particles and a resin are premixed is prepared, and then the master batch and the resin are combined by melt-kneading. In this case, as a method for producing a masterbatch, it is preferable to apply a wet mixing method from the viewpoint that damage to the resin composition is small and uniform mixing is possible. The wet mixing method is a method of preparing a masterbatch by dissolving a resin in an appropriately selected solvent and mixing the solvent in which the resin is dissolved and inorganic fine particles, and finally by volatilizing the solvent. A master batch can be obtained.

  Solvents applicable to the production of the masterbatch may be any solvents that can dissolve the resin composition, for example, aromatic hydrocarbons such as benzene, toluene, and xylene, and ketones such as acetone, methyl ethyl ketone, cyclohexanone, and heptanone. Esters such as ethyl acetate, acetic acid-t-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, diethylene glycol diethyl ether, tetrahydrofuran, ethers such as 1,3-dioxane, 1,4-dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfo Sid, N- methyl-2-pyrrolidone, can be mentioned aprotic polar solvents such as sulfolane. These solvents can be used alone or in combination of two or more.

  In the resin composition 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, and ultraviolet rays and electrons are mixed. It can be obtained by curing by either radiation or heat treatment.

  In the present invention, the correlation distance A of the two-phase structure in the resin composition is affected by the primary particle size, surface treatment method, volume fraction, etc. of the inorganic fine particles to be added, but the degree of mixing of the resin and the inorganic fine particles It is adjusted by optimizing.

  For example, when compounding inorganic fine particles and thermoplastic resin by melt kneading, the degree of mixing is controlled by the temperature during kneading, the number of rotations of the screw of the kneading device and the design (shape), and the temperature during kneading is lowered. By an operation such as increasing the number of rotations of the screw, the kneading torque is increased and mixing proceeds. However, if the kneading torque is excessively increased, the coloring of the resin proceeds due to heat generation or the like, and therefore it is necessary to control the optimum conditions. For example, when the value of the correlation distance A is attempted to be smaller than 1 nm, the coloration progresses and the transmittance of the resin decreases, so the correlation distance A of the resin composition of the present invention is in the range of 1 to 20 nm. Limited.

  In addition, as described above, a method of preparing a master batch in which inorganic fine particles and a resin are premixed at a predetermined mixing ratio in advance and then combining the master batch and the resin by melt kneading is a correlation of the present invention. This is an effective method for achieving the distance A (the condition defined in the above formula (1)).

  In the resin composition of the present invention, it is preferable that the correlation distance A and the root mean square B of the dielectric constant fluctuation satisfy the condition defined in the above formula (3). In addition to reducing the correlation distance A, the dielectric constant By reducing the mean square B of fluctuation, the condition defined in the above equation (3) can be satisfied.

  From the definition of the above formula (4), the square average B of dielectric constant fluctuation can be reduced by reducing the difference in refractive index between the resin phase and the inorganic fine particle phase constituting the resin composition. By selecting the composite oxide fine particles as the fine particles, the difference in refractive index between the resin phase and the inorganic fine particle phase can be reduced.

  Various molding materials can be obtained by molding the resin composition 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 resin composition 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 molded from the resin composition will be described with reference to FIG.

FIG. 2 is a schematic diagram showing the internal structure of the optical pickup device 1.
As shown in FIG. 2, 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-violet light (wavelength 380 to 420 nm) emitted from the semiconductor laser oscillator 2, the collimator 3, the beam splitter 4, and the ¼ wavelength plate 5 toward the direction away from the semiconductor laser oscillator 2. A diaphragm 6 and an objective lens 7 are sequentially arranged.

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

  The objective lens 7 that is an optical element is disposed at a position facing the optical disc D, and collects the blue-violet light emitted from the semiconductor laser oscillator 2 on one surface of the optical disc D. Yes. 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-violet light from the semiconductor laser oscillator 2 at the time of information recording operation on the optical disc D or at the time of reproducing information recorded on the optical disc D. As shown in FIG. 2, the emitted blue-violet light is transmitted through the collimator 3, collimated into infinite parallel light, then transmitted through the beam splitter 4, and transmitted through the quarter wavelength plate 5. Further, the blue-violet light is transmitted through the aperture 6 and the objective lens 7 to form a converged spot on the information recording surface D ₂ through the protective substrate D ₁ of the optical disc D.

Light that formed the concentrated light spot is modulated by the information recording surface D ₂ of the optical disk D by the information pit is 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. Thereafter, the reflected light passes through the sensor lens group 8 and is given astigmatism, is received by the sensor 9, and finally is photoelectrically converted by the sensor 9 to become an electrical signal.
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 11.5 g of alumina (Daimei Chemicals TM-300, average primary particle size 7 nm) was placed in a 300 cc eggplant flask, depressurized to 10 Torr or less, and heated at 190 ° C. for 1 hour. Thereafter, the inside of the eggplant flask was replaced with argon, 0.7 g of hexamethyldisilazane (HMDS-3 manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was well stirred at 300 ° C. for 2 hours to subject the alumina to a surface treatment. The obtained alumina fine particles were designated as “inorganic fine particles B”.

(1.3) Preparation of Inorganic Fine Particle C A mixed liquid of 463.1 g of pure water, 104.8 g of 26% ammonia water and 4255.0 g of methanol, and a mixed liquid of 3192 g of tetramethoxysilane (TMOS) and 229.4 g of methanol A mixture of 643.2 g of pure water and 104.8 g of 26% ammonia water was added dropwise over 150 minutes while maintaining the liquid temperature at 25 ° C., and then a mixture of 971 g of titanium tetraisopropoxide and 150 g of isopropanol was added to the mixture. It was added over a minute to obtain a silica / titanium mixed sol.

  When the mixed sol was heated and distilled under normal pressure, pure water was added dropwise while keeping the volume constant, and when it was confirmed that the top temperature of the distillation column reached 100 ° C. and the pH became 8 or less, pure water was used. Was completed to obtain a dispersion of inorganic fine particles.

  Further, 15.4 g of methyltrimethoxysilane was added to the dispersion, and the mixture was stirred at room temperature for 1 hour and then refluxed for 2 hours. Then, methyl ethyl ketone was added dropwise while keeping the volume constant by heating and distillation under normal pressure, and the addition was terminated when it was confirmed that the tower top temperature reached 79 ° C. and the water content was 1.0% or less. Cooled to room temperature. Thereafter, microfiltration was performed using a 3 μ membrane filter to obtain a methyl ethyl ketone-dispersed silica sol. Thereafter, silica / titanium mixed particles obtained by evaporating the solvent under reduced pressure and subjected to surface treatment were designated as “inorganic fine particles C”.

(1.4) Preparation of inorganic fine particles D 10 g of alumina (Aluminium Oxide C manufactured by Nippon Aerosil Co., Ltd., average primary particle size 13 nm) was added to a mixed solution of pure water 160 cc, ethanol 560 cc, and ammonia water (25%) 30 cc. The suspension was dispersed 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 stirring was continued for another hour, the pH of the dispersion was increased 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 using centrifugation, and the liquid was heated at 190 ° C. for 5 hours and dried to obtain white powdery inorganic fine particles, which were designated as “inorganic fine particles D”.

(2) Preparation of Sample (2.1) Preparation of Samples 1-1 to 1-4 As a resin, 30 parts by volume of the resin represented by Chemical Formula 2 described in Table 1, 15 parts by volume of inorganic fine particles A, and 200 volumes of cyclohexane. And these are prepared by T.K. K. Wet mixing was performed at 85 ° C. with Hibis Disper Mix 3D-20, and then deaeration and drying were performed to obtain a master batch A.

  Thereafter, a segment mixer KF6 was attached to a laboratory plastic mill μ manufactured by Toyo Seiki Seisakusho, and the masterbatch A and the resin represented by Chemical Formula 2 shown in Table 1 were introduced into the mixer and kneaded. Nitrogen gas was introduced into the system from the sample inlet to suppress air contamination. The kneaded material (resin composition) thus obtained was designated as “Samples 1-1 to 1-4”. At this time, the volume fraction Φ of the inorganic fine particles A in the samples 1-1 to 1-4 is Φ = 0.1 for the sample 1-1 and Φ = 0.2 for the sample 1-2. Φ = 0.3 for sample 1-3 and Φ = 0.4 for sample 1-4.

(2.2) Preparation of Samples 1-5 to 1-8 Except that the inorganic fine particles A were changed to the inorganic fine particles B, “Sample 1-5” was prepared in the same manner as described in the item (2.1) above. To 1-8 ". At this time, the volume fraction Φ of the inorganic fine particles B in the samples 1-5 to 1-8 is Φ = 0.1 for the sample 1-5 and Φ = 0.2 for the sample 1-6. Φ = 0.3 for sample 1-7 and Φ = 0.4 for sample 1-8.

(2.3) Preparation of Samples 1-9 to 1-10 Except that the inorganic fine particles A were changed to the inorganic fine particles C, “Sample 1-9” was prepared in the same manner as described in the item (2.1) above. To 1-10 ". At this time, the volume fraction Φ of the inorganic fine particles C in the samples 1-9 to 1-10 is Φ = 0.2 for the sample 1-9 and Φ = 0.3 for the sample 1-10. It was made to become.

(2.4) Preparation of Samples 1-11 to 1-12 As the resin, the resin represented by Chemical Formula 2 shown in Table 1 was prepared, and inorganic fine particles C were prepared as inorganic fine particles. These were dried at 260 ° C. for 6 hours under a nitrogen flow rate. Thereafter, a segment mixer KF6 was attached to a laboratory plast mill μ manufactured by Toyo Seiki Seisakusho, and the mixture was put into the mixer and kneaded. Nitrogen gas was introduced into the system from the sample inlet to suppress air contamination. The kneaded material (resin composition) thus obtained was designated as “Samples 1-11 to 1-12”. At this time, the volume fraction Φ of the inorganic fine particles C in the samples 1-11 to 1-12 is Φ = 0.2 for the sample 1-11 and Φ = 0.3 for the sample 1-12. It was made to become.

(2.5) Preparation of Samples 1-13 to 1-14 Except that the inorganic fine particles A were changed to the inorganic fine particles D, “Sample 1-13” was prepared in the same manner as described in the item (2.1) above. ~ 1-14 ". At this time, the volume fraction Φ of the inorganic fine particles D in the samples 1-13 to 1-14 is Φ = 0.2 for the sample 1-13 and Φ = 0.3 for the sample 1-14. It was made to become.

(2.6) Preparation of Samples 1-15 to 1-16 Except that the inorganic fine particles C were changed to the inorganic fine particles D, “Sample 1-15” was prepared in the same manner as described in the item (2.4) above. ˜1-16 ”. At this time, the volume fraction Φ of the inorganic fine particles D occupying the samples 1-15 to 1-16 is Φ = 0.2 for the sample 1-15 and Φ = 0.3 for the sample 1-16. It was made to become.

(3) Evaluation of sample (3.1) Evaluation method of correlation distance X-ray small angle scattering measurement is performed using a small angle wide angle X-ray diffractometer (RINT2500 / PC, manufactured by Rigaku Corporation), and each sample 1-1 to The correlation distance A at 1-16 was determined. The measurement was performed by the transmission method under the following measurement conditions. At this time, the thickness of each sample 1-1 to 1-16 was adjusted to 1 / μ (μ is the mass absorption coefficient of each sample 1-1 to 1-16).

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

Based on the obtained scattering pattern, a two-phase separation Debye model is applied using analysis software (manufactured by Rigaku Corporation: NANO-solver Ver3.0), model-free analysis is performed to obtain a correlation function, and a correlation is obtained therefrom. The distance A was calculated.
Here, the blank data necessary for the analysis was obtained by installing each measurement sample 1-1 to 1-16 on the incident side of the light receiving slit box and measuring under the same conditions. Table 2 shows the correlation distance A of each of the obtained samples 1-1 to 1-16.

(3.2) Evaluation Method of Refractive Index of Inorganic Fine Particles Each inorganic fine particle A, B, C, D was dispersed in DMSO (dimethyl sulfoxide; refractive index 1.48) and stirred. 1-bromonaphthalene (refractive index: 1.66) was added dropwise to the dispersion while stirring, and transmission was performed at a wavelength of 588 nm using a spectrophotometer (manufactured by Shimadzu Corporation: UV-3150) each time it was dropped. Rate was evaluated. The refractive index of the dispersion when the dispersion became transparent and the dispersion had the highest transmittance was measured using an automatic refractometer (KPR-200, manufactured by Kalnew Optical Industry), and the obtained 23 ° C. Was the refractive index n ₁ of each of the inorganic fine particles A, B, C, and D. The refractive index n ₁ of each inorganic fine particle A, B, C, D is shown in Table 2.

(3.3) Evaluation Method of Refractive Index and dn / dT Change Rate of Resin Composition Using an automatic refractometer (manufactured by Kalnew Optical Industry: KPR-200), the temperature of each sample 1-1 to 1-16 was set to 10 The refractive index at a wavelength of 588 nm was measured by changing the temperature from 0 ° C. to 60 ° C. The refractive index at 23 ° C. of each sample 1-1 to 1-16 is shown in Table 2 as the refractive index n ₂ of the resin composition.

Moreover, dn / dT in each sample 1-1 to 1-16 was calculated from the change in refractive index when the temperature of each sample was changed from 10 ° C. to 60 ° C. In addition, dn / dT was calculated by the same method for the resin to which none of the inorganic fine particles A, B, C, and D were added (the resin of Chemical Formula 2 described in Table 1). Based on these calculation results, the change rate of dn / dT of each sample 1-1 to 1-16 was calculated by the following formula. The calculation results are shown in Table 2. Table 2 also shows the refractive index n ₀ at 23 ° C. of the resin to which none of the inorganic fine particles A, B, C, and D are added.
dn / dT change rate = (dn / dT in resin−dn / dT in each sample 1-1 to 1-16) / (dn / dT in resin) × 100

(3.4) refractive index n ₁ of the inorganic fine particles obtained by the method described above the method of calculating the mean square of the dielectric constant _fluctuation, the refractive index n ₂ of the resin _composition, using a refractive index n ₀ of the thermoplastic resin below The two-row average of the dielectric constant fluctuation of each of the samples 1-1 to 1-16 was calculated by the equation. Table 2 shows the root mean square B of the obtained dielectric constant fluctuations.
B = (n ₀ ² −n ₂ ² ) ² · (1−Φ) + (n ₁ ² −n ₂ ² ) ² · Φ

(3.5) Measurement of light transmittance After each sample was heated and melted, each sample was molded into a plate having a thickness of 3 mm. About each obtained plate-shaped sample, 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.

(4) Summary As shown in Table 2, Samples 1-2 to 1-4, 1-6 to 1-10, 1-13, 1-14 and Comparative Samples 1-1, 1-5, 1-11 , 1-12, 1-15, and 1-16, Samples 1-2 to 1-4, 1-6 to 1-10, 1-13, and 1-14 show the light transmittance and dn / dT change. The result with rate is good. From the above, it is useful to satisfy the conditions defined in the above formulas (1) and (2) in realizing a resin composition and an optical element that are excellent in transparency and have a small refractive index change rate due to temperature. I understand.

[Example 2]

(1) Preparation of sample “Sample 2-1” was prepared in the same manner as in Sample 1-1 to 1-16 described in Example 1, except that polyester resin (O-PET4: manufactured by Kanebo) was used as the resin. ˜2-16 ”.

Next, the evaluation method of a resin composition is demonstrated.
(2) Evaluation of Samples Samples 1-1 to 1-16 were evaluated by the same method as in Example 1. The results obtained are listed in Table 3.

(3) Summary As shown in Table 3, Samples 2-2 to 2-4, 2-6 to 2-10, 2-13, 2-14 and Comparative Samples 2-1, 2-5, 2-11 , 2-12, 2-15, and 2-16, Samples 2-2 to 2-4, 2-6 to 2-10, 2-13, and 2-14 show changes in light transmittance and dn / dT. The result with rate is good. From the above, it is useful to satisfy the conditions defined in the above formulas (1) and (2) in realizing a resin composition and an optical element that are excellent in transparency and have a small refractive index change rate due to temperature. I understand.

[Example 3]
(1) Preparation of sample (1.1) Preparation of samples 3-1 to 3-4 As resin, curable resin 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate (Daicel Chemical Industries, Ltd.) 100 parts by mass of Celoxide 2021), 100 parts by mass of methylhexahydrophthalic anhydride (Epiclon B-650 manufactured by Dainippon Ink & Chemicals, Inc.) as a curing agent, and 2-ethyl-4-methylimidazole as a curing accelerator (2E4MZ manufactured by Shikoku Kasei Kogyo Co., Ltd.) and a phenolic antioxidant (tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenylpropionate)) as a stabilizer 0.1 part by mass of methane) and 0.1% of phosphorus stabilizer (2,2′-methylenebis (4,6-ditert-butylphenyl) -2-ethylhexyl phosphite) The same inorganic fine particles A as used in Example 1 were added and mixed, and dispersed using a desktop three-roll mill (RM-1 manufactured by Irie Shokai Co., Ltd.). .

  The obtained dispersion was defoamed using a rotating / revolving mixer (Shinky Awatori Nertaro AR-100), poured into a mold, and heated at 100 ° C. for 3 hours and further at 140 ° C. Curing was performed in an oven for 3 hours. The obtained colorless and transparent cured product was designated as “Samples 3-1 to 3-4”. At this time, the volume fraction Φ of the inorganic fine particles A in the samples 3-1 to 3-4 is Φ = 0.2 for the sample 3-1, Φ = 0.3 for the sample 3-2, The amount of inorganic fine particles added was adjusted such that Φ = 0.4 for 3-3 and Φ = 0.5 for sample 3-4.

(1.2) Preparation of Samples 3-5 to 3-8 Except that the inorganic fine particles A were changed to the same inorganic fine particles D used in Example 1, the same method as in the item (1.1) above. “Samples 3-5 to 3-8” were produced. At this time, the volume fraction Φ of the inorganic fine particles D occupying the samples 3-5 to 3-8 is Φ = 0.1 for the sample 3-5 and Φ = 0.3 for the sample 3-6. Φ = 0.4 for sample 3-7 and Φ = 0.5 for sample 3-8.

(2) Evaluation of Samples Samples 3-1 to 3-8 were evaluated by the same method as in Example 1. The results obtained are listed in Table 4.
The light transmittance was measured by cutting each sample 3-1 to 3-8 into a plate having a thickness of 3 mm. The dn / dT change rate was defined as the dn / dT change rate with respect to a cured product cured without adding inorganic fine particles.

(3) Summary As shown in Table 4, when Samples 3-2 to 3-4, 3-6 to 3-8 and Comparative Samples 3-1 and 3-5 are compared, Samples 3-2 to 3-3 4, 3-6 to 3-8 have good results of light transmittance and dn / dT change rate. From the above, it is useful to satisfy the conditions defined in the above formulas (1) and (2) in realizing a resin composition and an optical element that are excellent in transparency and have a small refractive index change rate due to temperature. I understand.

It is a schematic diagram of the two-phase structure which consists of an inorganic fine particle phase and a resin phase. 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 (4)

In a resin composition in which inorganic fine particles are dispersed in a resin,
When the correlation distance of the two-phase structure consisting of the inorganic fine particle phase and the resin phase is A, the inorganic fine particle satisfies the condition defined by the following formula (1) and occupies the resin composition. A resin composition characterized in that the volume fraction Φ satisfies a condition defined by the following formula (2), where Φ is a volume fraction of the above.
1 nm ≦ A ≦ 20 nm (1)
0.2 ≦ Φ ≦ 0.6 (2) The resin composition according to claim 1,
When the mean square of the dielectric constant fluctuation of the resin composition is B, the correlation distance A and the mean square B of the dielectric constant fluctuation satisfy the condition defined by the following formula (3). Resin composition.
A ³ × B ≦ 5.0 (3) In the resin composition according to claim 1 or 2,
The resin composition, 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 by using the resin composition according to any one of claims 1 to 3.

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