JP2009251093A - Optical composite material and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical composite material applicable even to uses where not only optical properties such as refractive index and Abbe's number but also practical properties such as moldability are required, and an optical element using the same. <P>SOLUTION: The optical composite material includes inorganic particles having a refractive index of ≥1.6 for a light beam of 589 nm wavelength and a resin. The optical composite material contains ≥1 mass% of fluorine and includes a refractive index of 1.48-1.6 for a light beam of 589 nm wavelength and an Abbe's number of ≥55. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel optical composite material applicable to optical elements such as lenses, filters, gratings, optical fibers, and flat optical waveguides.

  In recent years, research on composite materials using nanoparticles and resins has been actively conducted. In particular, by reducing the particle diameter of the nanoparticles and increasing the dispersibility in the resin, the transparency of the composite material is increased and application to an optical element is also possible. On the other hand, inorganic materials for optical elements include many materials that do not have properties such as high refractive index and low linear expansion coefficient. However, on the other hand, because of low molding processability, applicable applications are limited. The current situation is. For this reason, attempts have been made to improve the molding processability by taking advantage of the excellent optical properties of inorganic materials by combining inorganic materials and resins.

  In particular, when an inorganic material having a high refractive index is used, the refractive index of the composite material can be increased, and the merit is great. On the other hand, there are relatively few proposals relating to the control of the Abbe number representing the degree of wavelength dispersion and its important optical characteristics, but there are the following.

  In Patent Document 1, a high Abbe number material made of an organic polymer has been proposed. In such an invention, the Abbe number is increased mainly using inorganic particles (alumina) having anomalous dispersibility, but the surface treatment that can be applied to the particle surface is limited by the limited types of particles that can be actually applied. However, for example, the water absorption is inevitably deteriorated.

  In patent document 2, the proposal regarding the Abbe number and refractive index in the composite which has a zirconia is made. However, since a general acrylic resin is used as the base resin, the upper limit of the Abbe number is 60 or less, particularly when the refractive index is 1.5 or more, although the refractive index is high, the Abbe number is 55 or less. Furthermore, there is no intention to positively improve the Abbe number.

  Patent Document 3 proposes a composite material having a refractive index of 1.6 or more containing zirconia or the like. However, in order to achieve a high refractive index, it is necessary to increase the filling rate of the particles (volume ratio of 25% or more), and there is concern about molding processability, which is a merit of the resin, and it is not always practical.

  When the refractive index of the composite material is lowered, for example, when used as a lens, there arises a problem that the curvature becomes extremely large or the thickness is increased. PMMA (polymethylmethacrylate), which is known as a general-purpose resin for optical materials, has a refractive index of about 1.49. If the refractive index is equivalent, the design of the optical device is relatively easy. In the case of a low-refractive index composite material having a value of less than 48, the same optical design as before becomes difficult. In reality, the refractive index of the composite material needs to be 1.48 or more.

Thus, no concrete proposal has been made so far for a composite material that simultaneously satisfies properties such as refractive index, Abbe number, and moldability, which are physical properties that are practically important.
JP 2001-183501 A JP 2005-316219 A International Publication No. 2007-032217 Pamphlet

  The present invention has been made in view of the above problems, and its purpose is not only for optical characteristics such as refractive index and Abbe number, but also for optical applications applicable to practical applications such as molding processability. It is to provide a composite material and an optical element using the same.

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

  1. An optical composite material composed of an inorganic particle having a refractive index of a light beam having a wavelength of 589 nm of 1.6 or more and a resin, the optical composite material containing 1% by mass or more of fluorine, and a light beam having a wavelength of 589 nm. An optical composite material having a refractive index of 1.48 or more and 1.6 or less and an Abbe number of 55 or more.

  2. 2. The optical composite material as described in 1 above, wherein the resin has a refractive index of light having a wavelength of 589 nm of 1.4 or more.

  3. 3. The optical composite material as described in 1 or 2 above, wherein the resin is a resin containing 3% by mass to 60% by mass of fluorine.

  4). 4. An optical element formed by using the optical resin material according to any one of 1 to 3 above.

  According to the present invention, a novel optical composite material excellent in optical properties such as refractive index and Abbe number, molding processability, and the like, and an optical element using the same can be obtained.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  The optical composite material of the present invention is an optical composite material composed of inorganic particles having a refractive index of light having a wavelength of 589 nm and a resin of 1.6 or more, and the optical composite material contains 1% by mass or more of fluorine. The refractive index of light having a wavelength of 589 nm is 1.48 or more and 1.6 or less, and the Abbe number is 55 or more.

  First, the measurement of the Abbe number and the method of measuring the refractive index of inorganic particles, resin, and optical composite material will be described below.

<Measurement conditions>
(1) The Abbe number can be measured according to the following method.

  The Abbe number was measured by curing the optical composite material, processing and polishing it, and using an automatic refractometer (KPR-200, manufactured by Kalnew Optical Industry), Fraunhofer C line (656.3 nm), D line (589. 3 nm) and F-line (486.1 nm), the respective refractive indexes, nc, nd, and nf are measured and calculated from the following formula.

Abbe number (νd) = (nd−1) / (nf−nc)
(2) Refractive Index of Inorganic Particles Inorganic particles are dispersed in various solvents with adjusted refractive indexes, the absorbance of the dispersion with respect to light having a wavelength of 589 nm is measured, and the refractive index of the solvent having the minimum value is measured. Thus, the refractive index of the inorganic particles is determined.
(3) Refractive Index of Resin and Optical Composite Material As a method for measuring the refractive index, for example, ellipsometry, spectral reflectance method, optical waveguide method, Abbe method, minimum deviation method, etc. A preferred method can be selected depending on the form.

  For example, a resin or optical composite material is cured, processed and polished, and the refractive index of light having a temperature of 25 ° C. and a wavelength of 589 nm is measured using an automatic refractometer (KPR-200, manufactured by Kalnew Optical Industry). The refractive index of the resin or the optical composite material.

<< Optical properties of composite materials >>
In applications such as an optical element in which the Abbe number is particularly important as an optical characteristic, even if the refractive index of light having a wavelength of 589 nm is 1.6 or less, for example, the content of fluorine atoms described below can be increased to increase the Abbe number. It may be desirable. Therefore, in such a case, it is preferable to increase the addition amount of particles having a high refractive index so as not to sacrifice the moldability including the fluidity before curing and to make a composite with the resin.

  For example, an amorphous resin containing fluorine is known as a material that imparts a high Abbe number. Asahi Glass's Cytop and DuPont's Teflon (registered trademark) AF show an extremely large value of Abbe number of 90 or more, and the wavelength dependency of the refractive index is very small. However, since the refractive index is too low, there is a disadvantage that the thickness increases extremely when used as a lens. Furthermore, if a resin having a high refractive index is combined with these resins to increase the refractive index of light having a wavelength of 589 nm to be 1.48 or more, it is necessary to increase the packing ratio of the particles. It is very brittle, cracks during molding are prone to occur remarkably, and practicality is often impaired. Further, when the particle filling rate is increased (for example, 30% by volume or more), fluidity before curing of the composite material, which is one of the important factors in molding processability, is lowered, leading to an increase in molding cost. In the case of an optical composite material, the refractive index of a light beam having a wavelength of 589 nm is more preferably 1.5 or more. Therefore, the Abbe number, the refractive index, and the moldability are often in a balance of performance.

  Therefore, as a result of intensive studies, the present inventors have prepared a fluorine atom-containing resin base material in which the refractive index as a resin does not extremely decrease, that is, the refractive index is 1.4 or more and the Abbe number is 60 or more. For such a resin base material, a high refractive index particle is composited so as to be 10 to 20% by volume, which is a practical optical characteristic, refractive index> = 1.48, and a high Abbe number (55 It has been found that the above can be achieved. By suppressing the filling rate of the high refractive index particles so that the refractive index of the optical composite material having a wavelength of 589 nm does not exceed 1.6, the resin has excellent molding processability while obtaining practical optical characteristics. It has been found that it is possible to make a low-cost composite material for optical use.

  The optical composite material of the present invention preferably has transparency in the visible region wavelength. The transparency of the optical composite material of the present invention is generally 60% or more, preferably 70% or more, more preferably 80% or more, and most preferably 85% when the light transmittance in the visible region wavelength is 3 mm. The above is desirable. Such measurement is performed, for example, by a test according to the ASTM D-1003 (3 mm thickness) standard. The visible region here means a wavelength region of 400 to 650 nm.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

<Fluorine content>
The optical composite material of the present invention contains 1% by mass or more of fluorine. The following forms are possible for containing fluorine.
(1) Form contained in resin As a fluorine-containing resin, it can be contained in various thermoplastic and thermosetting resins. In general, fluorine is introduced in a state of being directly bonded to carbon. Fluorine-containing resins are roughly classified into partial fluororesins and perfluororesins, and each is broadly classified into crystalline and amorphous resins. In order to obtain transparency, it is necessary that the resin be amorphous. In particular, the refractive index of light having a wavelength of 589 nm is preferably 1.4 or more, and for this purpose, partial fluorination is required. It is preferable.

  Some of the amorphous fluorine-containing resins are already known. Cytop (made by Asahi Glass), Teflon (registered trademark) AF (made by DuPont) and the like are known as resins having high transparency and a large Abbe number. Although it is possible to use these resins, these resins usually have a high fluorine content because they are perfluororesins in which all of the hydrogen contained in the resin is replaced with fluorine in a C—H bond state. (60 mass% or more). Therefore, the refractive index is very low as 1.4 or less, and it is difficult to increase the refractive index to 1.48 or more by adding a relatively small amount (20% by volume or less) even by compositing with particles having a high refractive index. is there. That is, it is difficult to obtain a necessary refractive index while maintaining moldability.

Therefore, in the present invention, it is preferable to use a resin having a partially reduced C—H bond and a reduced fluorine content, such as a partially fluorinated resin. In addition, the fluorine content can be adjusted by changing the substitution rate of H by fluorine in the monomer before polymerization, and all fluorinated monomers, no hydrogen in the monomers, or monomers that are not partially fluorinated It can be adjusted by changing the copolymerization ratio. For example, when an acrylic monomer is used, an appropriate ratio is obtained by copolymerizing a fluorine-containing monomer such as trifluoroethyl methacrylate, 2- (perfluorooctyl) ethyl methacrylate, or perfluoroadamantane methacrylate with respect to the methyl methacrylate monomer. It is possible to produce a resin containing fluorine.
(2) Form contained in surface treatment agent for particles The surface treatment of inorganic particles is preferable because the particles are uniformly contained in the resin. Fluorine can be contained in the optical composite material by containing fluorine in the surface treatment agent (with physical adsorption and chemical adsorption on the particle surface) on the particle surface. The surface treatment will be described later, but various compounds such as a silane coupling agent containing fluorine, a carboxylic acid containing fluorine, an amine, and an amide are applicable.
(3) Form in which the surface of the inorganic particles contains fluorine atoms For example, when various metal oxide particles are used as the inorganic particles, by substituting the surface oxygen atoms with fluorine ions, a part of the inorganic particles becomes an optical composite material. Fluorine can be contained. For example, by contacting a metal oxide (MOx) with HF gas in a gas phase, an MFx bond can be created on the particle surface, and oxygen on the particle surface can be replaced with fluorine. In this way, fluorine atoms can be contained in the optical composite material at an appropriate ratio.
(4) Form in which an additive containing fluorine is added The compound containing fluorine can be added to the optical composite material by adding it as an additive. Additives containing fluorine include nanoparticulate fluororesin, perfluorocarboxylic acid and its salt, anion and its salt such as fluoroamide and TFSI, etc. Even when there is no agent function), fluorine can be contained by appropriately mixing alone in the optical composite material.

  In the present invention, it is essential that the optical composite material contains 1% by mass or more of fluorine. As long as it is satisfied, for example, the amount of fluorine contained in the resin in (1) is not particularly limited. However, if the amount of fluorine is too small, the effect of increasing the Abbe number cannot be expected so much. If the amount is too large, the decrease in the refractive index of the resin becomes too large and the application to optical materials is limited. Preferably, it is 10-50 mass%.

"resin"
Next, the resin according to the present invention will be described.

  In the optical composite material of the present invention, the above inorganic particles can be combined with either a thermoplastic resin or a curable resin (by energy rays). Although it does not specifically limit as resin, As above-mentioned, it is also preferable that resin contains a fluorine as a functional group. In that case, the resin is preferably a resin containing 3% by mass to 60% by mass of fluorine. When the fluorine content in the resin is within the above range, it is a preferable embodiment for obtaining the effect of the present invention that the refractive index and the Abbe number of the optical composite material are compatible.

  The thermoplastic resin is not particularly limited as long as it is a transparent thermoplastic resin material generally used as an optical material or a resin partially substituted with fluorine, but considering the processability as an optical element, An acrylic resin, a cyclic olefin resin, a polycarbonate resin, a polyester resin, a polyether resin, a polyamide resin, or a polyimide resin is preferable, and a resin having a cyclic olefin structure (including an adamantyl group) is particularly preferable. Since these resins have a C—H structure, fluorine atoms can be introduced into the resin at a desired ratio by replacing a part thereof with C—F bonds.

  On the other hand, the curable resin can be cured by any of ultraviolet and electron beam irradiation or heat treatment, and is mixed with inorganic particles in an uncured state and then cured to form a transparent resin composition. Any material can be used as long as it forms a product, and examples thereof include epoxy resins, vinyl ester resins, silicone resins, acrylic resins, and allyl ester resins. Since these resins also have a C—H structure, fluorine atoms can be introduced into the resin at a desired ratio by replacing a part thereof with C—F bonds. The curable resin may be an actinic ray curable resin that is cured by irradiation with ultraviolet rays or an electron beam, or may be a thermosetting resin that is cured by a heat treatment, for example, listed below. Such types of resins can be preferably used.

(acrylic resin)
As the acrylic resin used in the present invention, a resin having a general structure can be used, but it is particularly preferable to have an alicyclic hydrocarbon skeleton. Of the alicyclic hydrocarbon skeletons, polycyclic hydrocarbon compounds are more preferable. As specific examples, those having an aliphatic polycyclic structure and containing a three-dimensional cross-linked structure are preferable, and particularly preferable compounds include compounds represented by the general formula (1) such as tricyclodecanedi. Methanol dimethacrylate, tricyclodecane dimethanol diacrylate, a compound represented by general formula (2), for example, adamantyl methacrylate, adamantyl acrylate, etc., a compound represented by general formula (3), for example, isobornyl Methacrylate, isobornyl acrylate, vinyl norbornene and the like can be mentioned.

(Silicone resin)
The silicone resin is a resin having a siloxane bond —Si—O— in which silicon (Si) and oxygen (O) are alternately bonded as a main chain.

  As the silicone resin, a silicone resin made of a predetermined amount of polyorganosiloxane resin can be used (for example, see JP-A-6-9937).

  The thermosetting polyorganosiloxane resin is not particularly limited as long as it becomes a three-dimensional network structure with a siloxane bond skeleton by a continuous hydrolysis-dehydration condensation reaction by heating. It exhibits curability and has the property of being hard to soften even if reheated once cured.

  Such a polyorganosiloxane resin includes the following general formula (A) as a structural unit, and the shape thereof may be any of a chain, a ring, and a network.

Formula (A)
(R1, R2, SiO) n
In the general formula (A), R1 and R2 each represent the same or different substituted or unsubstituted monovalent hydrocarbon group. Specifically, as R1 and R2, as alkyl groups such as methyl group, ethyl group, propyl group, and butyl group; alkenyl groups such as vinyl group and allyl group; aryl groups such as phenyl group and tolyl group; cyclohexyl group, Cycloalkyl groups such as cyclooctyl groups, or groups in which hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms, cyano groups, amino groups, etc., such as chloromethyl groups, 3,3,3-trifluoro Examples thereof include a propyl group, a cyanomethyl group, a γ-aminopropyl group, and an N- (β-aminoethyl) -γ-aminopropyl group. R1 and R2 may each be a group selected from a hydroxyl group and an alkoxy group. Moreover, n in the said general formula (A) shows an integer greater than or equal to 50.

  The polyorganosiloxane resin is usually used after being dissolved in a hydrocarbon solvent such as toluene, xylene or petroleum solvent, or a mixture of these with a polar solvent. Moreover, you may mix | blend and use what differs in a composition in the range which mutually melt | dissolves.

  The method for producing the polyorganosiloxane resin is not particularly limited, and any known method can be used. For example, it can be obtained by hydrolysis or alcoholysis of one or a mixture of two or more organohalogenosilanes. Polyorganosiloxane resins generally contain hydrolyzable groups such as silanol groups or alkoxy groups. A group is contained in an amount of 1 to 10% by mass in terms of a silanol group.

  These reactions are generally performed in the presence of a solvent capable of melting the organohalogenosilane. It can also be obtained by a method of synthesizing a block copolymer by cohydrolyzing a linear polyorganosiloxane having a hydroxyl group, an alkoxy group or a halogen atom at the molecular chain terminal with an organotrichlorosilane. The polyorganosiloxane resin thus obtained generally contains the remaining HCl, but in the composition of the present embodiment, the storage stability is good, so that the one having 10 ppm or less, preferably 1 ppm or less is used. Is good.

  A silicone resin having a structure such as silsesquioxane is also preferable. It is possible to have various silsesquioxane structures such as a ladder type and a saddle type.

  Although the thermoplastic and curable resin material according to the present invention has an aromatic ring, the refractive index is improved, but the effect of improving the Abbe number due to the fluorine content is offset. Is 10% by mass or less.

  In the thermoplastic and curable resin material according to the present invention, the water absorption is preferably 0.2% by mass or less. Examples of the resin having a water absorption of 0.2% by mass or less include thermoplastic resins such as polyolefin resins (for example, polyethylene and polypropylene), fluororesins (for example, polytetrafluoroethylene, Teflon (registered trademark) AF (DuPont). ), Cytop (Asahi Glass Co., Ltd.), etc., cyclic olefin resins (for example, ZEONEX (manufactured by Zeon Corporation), Arton (manufactured by JSR Corporation), Appel (manufactured by Mitsui Chemicals), TOPAS (manufactured by Polyplastics Corporation), etc. ), Indene / styrene-based resin, polycarbonate, and the like, but are not limited thereto, and among these resins, resins having a partially fluorinated structure are preferable. It is also preferable to use other resins compatible with these resins. When two or more kinds of resins are used, the water absorption is considered to be substantially equal to the average value of the water absorption of each resin, and the average water absorption may be 0.2% or less. In the case of a curable resin, an acrylic resin having an alicyclic structure, a resin having an adamantyl group, and the like are preferable from the viewpoint of low water absorption. Moreover, it is also preferable to use a partially fluorinated monomer or a perfluoromonomer for a part or all of the monomers constituting the curable resin.

  From the viewpoint of heat resistance, it is preferable to use a resin having an adamantane skeleton. As curable resins having an adamantane skeleton, 2-alkyl-2-adamantyl (meth) acrylate (see JP 2002-193883 A), 3,3′-dialkoxycarbonyl-1,1′-biadamantane (JP 2001-253835), 1,1′-biadamantane compound (see US Pat. No. 3,342,880), tetraadamantane (see JP 2006-169177), 2-alkyl-2- A curable resin having an adamantane skeleton having no aromatic ring such as hydroxyadamantane, 2-alkyleneadamantane, and di-tert-butyl 1,3-adamantanedicarboxylate (see JP-A-2001-322950), bis (hydroxyphenyl) Adamantanes and bis (glycidyloxyphenyl) ada Lanthanum (JP-A-11-35522, JP-A No. see JP 10-130371) and the like can be used.

  Further, bromine-containing (meth) allyl ester not containing an aromatic ring (see JP-A-2003-66201), allyl (meth) acrylate (see JP-A-5-286896), allyl ester resin (JP-A-5-286896). No., JP-A-2003-66201), copolymers of acrylates and epoxy group-containing unsaturated compounds (see JP-A-2003-128725), acrylate compounds (see JP-A-2003-147072) An acrylic ester compound (see JP 2005-2064 A) can be preferably used.

When producing using a curable resin, in an optical composite material, it is preferable that a crosslinking density is 0.1 mmol / cm < ³ > or more.

The crosslink density of the optical composite material defined here can be determined according to various methods. For example, a method of measuring E ′ from measurement of viscoelasticity and obtaining it from the change can be easily applied. It is also possible to calculate the number of crosslinking points from the content of the crosslinkable monomer. For example, when the specific gravity is 1.2 with a cured product of ethylene glycol dimethacrylate (molecular weight 198), the number of moles per cm ³ is
1.2 / 198 × 1000 = 6.06 mmol
Assuming that 80% of the double bonds react and contribute to crosslinking, the crosslinking density is
6.06 × 0.8 = 4.85 mmol / cm ³
It can be asked. The reaction rate of the double bond can be determined by NMR or Raman spectroscopy.

  Now, the crosslinking density according to the present invention can be controlled by the following method.

(Control method using polyfunctional monomer)
When a monomer having a plurality of polymerizable functional groups in one molecule is used, the crosslinking density increases. In particular, when the number of crosslinkable functional groups per molecular weight is large, the crosslink density increases. In the case of acrylic resin, various monomers such as bifunctional monomers such as ethylene glycol dimethacrylate, tetrafunctional monomers such as pentaerythritol tetramethacrylate, and hexafunctional monomers such as dipentaerythritol hexamethacrylate are used. Is possible.

(Control method to provide many functional groups on the particle surface)
Since the particle surface also serves as a crosslinking point, it is also preferable to provide a crosslinking point on the particle surface.

(Control method using a crosslinking agent)
For example, in the case of an acrylic resin, a reaction of a sulfur compound easily proceeds in addition to the chain extension of a double bond. For example, the number of crosslinking points can be increased by using a crosslinking agent containing a plurality of mercapto groups. Peroxides are also applicable. In addition, various crosslinking agents such as polymer type crosslinking agents can be applied.

The crosslink density of the composite obtained by these methods is more preferably 0.2 mmol / cm ³ or more. A material having a sufficiently high crosslink density is preferable because so-called Tg disappears, sensitivity to heat is reduced, and heat resistance is improved. There is no particular upper limit to the crosslinking density, but the upper limit of the amount of crosslinkable functional groups that can be introduced is substantially limited to 10 mmol / cm ³ or less.

  In addition, the amount of initiator, selection of type, reaction temperature, energy ray irradiation state, oxygen, water content, etc. are also affected.

<< Applicable inorganic particles >>
As the inorganic particles, various particles can be used as long as the refractive index of light having a wavelength of 589 nm is 1.6 or more. The refractive index is further preferably 1.65 or more, and most preferably 1.8 or more. Specifically, oxide particles, metal salt particles such as carbonates and sulfates, and sulfide particles are preferably used. Among these, those that do not generate absorption, light emission, fluorescence, etc. in the wavelength region used as an optical element. Is preferably selected and used.

As oxide 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 kinds of metals can be used. Specifically, for example, titanium oxide, zinc oxide, aluminum oxide (alumina), zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, oxidation Magnesium, barium oxide, indium oxide, tin oxide, lead oxide, double oxides composed of these oxides, lithium niobate, potassium niobate, lithium tantalate, aluminum Magnesium oxide in (MgAl ₂ O ₄₎ or the like of the particles and composite particles, the refractive index are those satisfying 1.6 or more.

  In addition, rare earth oxides can also be used as oxide particles, specifically, scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide. Dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, and the like. In addition, Ti and Zr oxo clusters are also applicable.

  As the metal salt particles, carbonates, phosphates, sulfates, and composite particles thereof having a refractive index of light having a wavelength of 589 nm of 1.6 or more are applicable.

  As a method for preparing the inorganic particles, it is possible to obtain fine particles by spraying and firing the raw material of the inorganic particles in the gas phase. Furthermore, a method of preparing particles using plasma, a method of ablating raw material solids with a laser or the like to make fine particles, a method of oxidizing evaporated metal gas to prepare fine particles, and the like can be suitably used. Further, as a method for preparing in the liquid phase, it is possible to prepare an inorganic particle dispersion liquid which is dispersed as substantially primary particles by using a sol-gel method using an alkoxide or chloride solution as a raw material. Alternatively, it is possible to obtain a dispersion having a uniform particle size by using a reaction crystallization method utilizing a decrease in solubility.

  It is preferable to stably extract the function of the inorganic particles by drying and firing the particles obtained in the liquid phase. For drying, means such as freeze drying, spray drying, and supercritical drying can be applied, and the firing is performed not only by raising the temperature while controlling the atmosphere but also by using an organic or inorganic sintering inhibitor. It is preferable.

Among these particles, it is cheap and it is possible to select inorganic particles in consideration of safety. Further, considering the ease of reducing the particle size, TiO ₂ , Al ₂ O ₃ , LiNbO ₃ , Nb It is particularly preferable to use ₂ O ₅ , ZrO ₂ , Y ₂ O ₃ , MgO, ZnO, SnO ₂ , Bi ₂ O ₃ , ITO, CeO ₂ , AlN, diamond, KTaO ₃ or the like.

  From the viewpoint of improving the refractive index and increasing the Abbe number, it is preferable to apply diamond particles (refractive index of about 2.4). Diamond particles include an explosion method, an impact compression method, and a static pressure. Particles obtained by an explosion method or an impact compression method are preferable because of their dispersibility. Since the skeleton itself is essentially non-polar and has low hygroscopicity, it is preferable to use it as an optical composite material because it can reduce hygroscopicity when applied in a state where hydrophilic functional groups that are likely to be generated on the surface are removed. .

  The particles applicable to the present invention have a volume average particle diameter of 20 nm or less, and more preferably 1 nm or more and 15 nm or less. This is because when the average particle diameter is less than 1 nm, it is difficult to disperse the particles and the desired performance may not be obtained. Therefore, the average particle diameter is preferably 1 nm or more. On the other hand, when the average particle diameter exceeds 15 nm, the optical composite material obtained may become turbid depending on the difference in refractive index and the transparency may be lowered. Therefore, the average particle diameter is preferably 15 nm or less. Here, an average particle diameter means the volume average value of the diameter (sphere conversion particle size) when each particle is converted into a sphere having the same volume.

  There are no particular restrictions on the filling rate of the resin, but when filling the resin with inorganic particles with a large specific surface area of 15 nm or less, 30% by volume is required when ensuring moldability (fluidity, no cracks). It is practically difficult to exceed, and it is 25% by volume or less. On the other hand, in order to obtain optical characteristics (refractive index, Abbe number) by filling with inorganic particles, a certain degree of filling rate is required, preferably 5% by volume or more, more preferably 10% by volume or more. The increase in the refractive index accompanying this is preferably 0.02 or more, more preferably 0.05 or more, relative to the original resin. Depending on the refractive index and packing rate of the particles to be selected, a refractive index improvement of 0.2 or more can be expected, but high packing is required, or particles with a large refractive index difference are required, and light scattering is likely to occur. Therefore, it is not always preferable.

<Surface treatment agent>
Since it is necessary to uniformly mix the inorganic particles with the resin, the surface treatment of the particles is necessary to increase the affinity with the resin. For the bonding between the necessary surface treating agent and the particle surface, the following introduction methods are conceivable, but not limited to them.

A. Physical adsorption (secondary binding activator treatment)
B. Utilization reaction of surface chemical species (covalent bond with surface hydroxyl group)
C. Surface introduction and reaction of active species (introduction of active sites such as radicals and graft polymerization, high energy ray irradiation and graft polymerization)
D. Resin coating (encapsulation, plasma polymerization)
E. Deposition immobilization (deposition of sparingly soluble organic acid salts)
Further specific examples are as follows.
(1) Silane coupling agent As a silane coupling agent, various coupling agents are applicable. A coupling agent containing an aromatic ring or sulfur is desirable from the viewpoint of increasing the refractive index. The coupling agent containing sulfur can be introduced as a functional group such as a —SH group or a disulfide. For the aromatic ring, if the introduction amount is too large, the Abbe number decreases even if the refractive index increases, so the introduction amount has an upper limit, preferably 10% by mass or less of the total mass of the silane coupling agent, More preferably, it is 5 mass% or less. Further, as described above, when fluorine is introduced into the surface treatment agent, a silane coupling agent containing fluorine is preferably used.

  Specific examples of the silane coupling agent include: Shin-Etsu Chemical Co., Ltd. KBM-303, KBM-403, KBM-402, KBM-403, KBM-1403, KBM-502, KBM-503, KBE-502, KBE- 503, KBM-603, KBE-603, KBM-903, KBE-903, KBE-9103, KBM-802, KBM-803, KBM-3103, KBM-7103, and the like.

  Two or more coupling agents may be used in combination. In addition to the silane coupling agents shown above, other silane coupling agents may be used. Other silane coupling agents include alkyl esters of orthosilicate (eg, methyl orthosilicate, ethyl orthosilicate, n-propyl orthosilicate, i-propyl orthosilicate, n-butyl orthosilicate, sec-butyl orthosilicate, orthosilicate). Acid t-butyl) and its hydrolyzate.

(2) Other coupling agents Titanate, aluminate, and zirconate coupling agents are also applicable. Further, zircoaluminate, chromate, borate, stannate, isocyanate and the like can be used. A diketone coupling agent can also be used.
(3) Surface treatment agent Alcohols, nonionic surfactants, ionic surfactants, carboxylic acids, amines, and the like are applicable.
(4) Resin-based surface treatment After introducing active species to the particle surface by the methods (1) to (3) above, a method of providing a polymer layer on the surface by graft polymerization, or adsorbing a pre-synthesized polymer dispersant to the particle surface , There is a method of combining. In order to provide a polymer layer more firmly on the particle surface, graft polymerization is preferred, and grafting at a high density is particularly preferred.

<< Optical Element Manufacturing Method >>
In producing the optical element of the present invention, first, an optical composite material precursor (a molten state when a thermoplastic resin is used, or an uncured state when a curable resin is used) is prepared.

  Particularly when a curable resin is used, the optical composite material precursor may be prepared by mixing the curable resin dissolved in a solvent and the particles according to the present invention, and then removing the organic solvent. Alternatively, it may be prepared by adding and mixing the particles according to the present invention in a monomer solution which is one of the raw materials of the curable resin, followed by polymerization. Further, it may be prepared by melting an oligomer in which a monomer is partially polymerized or a low molecular weight polymer, and adding and mixing the particles according to the present invention thereto.

  In particular, in the present invention, a method is preferred in which a curable resin is used and the particles according to the present invention are added to the monomer solution and then polymerized, and in particular, a highly viscous solution in which the monomer and the particles according to the present invention are mixed is used. A method of mixing by giving a share while cooling is preferred. At this time, it is also important to adjust the viscosity so that the dispersion of the particles according to the present invention in the curable resin is optimized. Examples of the method for adjusting the viscosity include adjustment of the particle diameter, surface state, and addition amount of the particles according to the present invention, addition of a solvent and a viscosity modifier, etc. Since it is easy, an optimal kneading state can be obtained.

  In the case of compounding by giving a share, the particles according to the present invention can be added in a powder or agglomerated state. Or it is also possible to add in the state disperse | distributed in the diluent. When adding in the state disperse | distributed in the liquid, it is preferable to devolatilize a diluent after 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 0.001 to 0.5 mm are particularly preferable.

  The particles according to the present invention are preferably added in a surface-treated state, but it is also possible to use a method such as an integral blend in which a surface treatment agent and particles are added simultaneously to form a composite with a curable resin. Is possible.

<Saturated water absorption>
The optical composite material may absorb water due to environmental changes. The water absorption is preferably small because it causes fluctuations in optical characteristics and also causes deterioration in mechanical properties. For example, the saturated water absorption measured in an atmosphere at 65 ° C. and 90% relative humidity is preferably 3.0% by mass or less.

The following three points are mainly important for controlling the saturated water absorption amount.
(1) Reduce the saturated water absorption of the resin itself (2) Reduce the saturated water absorption of the particles (3) Reduce the water absorption of the surface treatment agent To reduce the water absorption of the resin itself, it is necessary to lower the polarity of the resin It is. For this reason, it is preferable to reduce the content of oxygen-containing functional groups such as hydroxyl groups and esters, various functional groups exhibiting properties such as acids and bases, sulfur and nitrogen. In the case of acrylic resins and epoxy resins, the crosslinkable functional groups often have polarity. Therefore, the number of the crosslinkable functional groups should be kept as low as possible while ensuring the necessary crosslink density, and unreacted functional groups may be reduced. preferable.

  It is also important to reduce the saturated water absorption of the particles. Since particles having a refractive index of 1.6 or more have less voids, micropores and the like inside the particles and preferably have a crystal structure, it is considered that moisture adsorbed on the surface is particularly related to the saturated water absorption. It is considered that the moisture adsorbed on the particle surface is adsorbed on the polar functional group on the surface. In the case of a metal oxide, it is mainly a hydroxyl group, and in the case of particles made of a salt such as sulfate or carbonate, surface polarization, partial deviation of composition, etc. can be mentioned as polar functional groups. Various polar functional groups can be considered for nitride and sulfide particles, but hydroxyl groups due to impurities can also be a cause.

  As an effective technique for controlling these, treatment with an organic functional group and treatment with an inorganic material can be considered.

  As the treatment with the organic functional group, use reaction of the surface hydroxyl group in the previous surface treatment can be considered. Although it is particularly preferable to use a silicon-based reactant typified by hexamethyldisilazane, various treatment agents such as organic fluorine compounds and hydrocarbon-based treatment agents are applicable.

  As a treatment with an inorganic material, a treatment using silicone or fluorine can be considered. Examples of silicone include monomethylpolysiloxane, dimethylpolysiloxane, and cyclic dimethylsiloxane compounds. In particular, silicone having SiH groups such as monomethylpolysiloxane is preferred.

  Examples of the treatment using fluorine include fluorination of the particle surface as described above. A very strong acid such as hydrofluoric acid strongly dissolves inorganic particles, but it may be possible to fluorinate only the outermost surface if the amount is reduced and gradually reacted. Alternatively, water absorption can be reduced by mixing fluorine with other fluorine-containing compounds (such as ammonium fluoride) and heating under appropriate conditions to introduce fluorine into the particle surface and reduce hydroxyl groups.

  In addition, for particles having a cationic surface, water absorption can be reduced by adding an anion that becomes hydrophobic when a salt is formed, such as 1,1,1-trifluoromethanesulfonimide. Sometimes.

<< Other additives for optical elements >>
In addition to the curable resin and the particles according to the present invention, various additives may be added to the optical element of the present invention when preparing an optical composite material or manufacturing an optical element, depending on the respective use. Also good. Examples of the additives include resin improvers such as plasticizers, antioxidants, light stabilizers, heat stabilizers, weather stabilizers, stabilizers such as ultraviolet absorbers and near infrared absorbers, lubricants, soft polymers, , Anti-clouding agents such as alcoholic compounds, colorants such as dyes and pigments, other antistatic agents, flame retardants and the like. They may be used alone or in combination.

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

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

<Antioxidant>
Antioxidants applicable to the optical element of the present invention include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. By blending these antioxidants, it is possible to prevent lens coloring and strength reduction due to oxidative degradation during molding of the optical resin material without lowering transparency, heat resistance and the like.

  As the phenolic antioxidant, conventionally known ones can be applied. For example, 2-t-butyl-6- (3-t-butyl-2-hydroxy- described in JP-A No. 63-179953). 5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate, etc. Acrylate compounds such as octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate described in JP-A-1-168463, and 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-to (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenylpropionate)) methane, , Pentaerythrmethyl-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenylpropionate)), triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5- Alkyl-substituted phenolic compounds such as methylphenyl) propionate), 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 - triazine group-containing phenol compounds such as triazine.

  The phosphorus-based antioxidant is not particularly limited as long as it is a substance that is usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris ( Nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl)- Monophosphite compounds such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di- Tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C 5) phosphite) diphosphite compounds such as and the like. Among these, monophosphite compounds are preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.

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

  Furthermore, in addition to the above-mentioned phenol-based, phosphoric acid-based and sulfur-based antioxidants, amine-based antioxidants such as diphenylamine derivatives, nickel or zinc thiocarbamates, and the like are also applicable as antioxidants.

  The above-mentioned antioxidants can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range that does not impair the object of the present invention. It is preferably in the range of 0.001 to 20 parts by mass, more preferably in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass.

<Anti-clouding agent>
As a cloudiness inhibitor applicable to the optical element of the present invention, it is preferable to blend a compound having the lowest glass transition temperature of 30 ° C. or lower. Thereby, it is possible to prevent white turbidity of the optical element when stored in a high-temperature and high-humidity environment for a long time without reducing various properties such as transmittance, heat resistance, and mechanical strength.

<Light stabilizer>
Light-resistant stabilizers (light stabilizers) that can be applied to the optical element of the present invention are roughly classified into quenchers and radical scavengers. Benzophenone light stabilizers, benzotriazole light stabilizers, and triazine light stabilizers are classified as quenchers, and hindered amine light stabilizers are classified as radical scavengers. In the present invention, it is preferable to use a hindered amine light stabilizer (HALS) from the viewpoints of transparency of the optical element, coloration resistance and the like. Specific examples of such HALS can be selected from low molecular weight, medium molecular weight, and resin amount.

  For example, LA-77 (manufactured by ADEKA Co., Ltd.), Tinuvin 765 (manufactured by Ciba Japan Co., Ltd., hereinafter abbreviated as CJ), Tinuvin 123 (manufactured by CJ), Tinuvin 440 (manufactured by CJ) ), Tinuvin 144 (manufactured by CJ), Hostavin N20 (manufactured by Hoechst) as medium molecular weight, LA-57 (manufactured by ADEKA), LA-52 (manufactured by ADEKA), LA-67 (manufactured by ADEKA) LA-62 (manufactured by ADEKA), LA-68 (manufactured by ADEKA), LA-63 (manufactured by ADEKA), Hostavin N30 (manufactured by Hoechst), Chimassorb 944 (manufactured by CJ), Chimassorb 2020 (manufactured by CJ), Chima Sorb119 (manufactured by CJ), TINUVIN 622 (manufactured by CJ), CyasorbUV-3346 (manufactured by Cytec), CyasorbUV-3529 (manufactured by Cytec), and the like Uvasil299 (manufactured by GLC). In particular, it is preferable to use a low and medium molecular weight HALS for the molded body (optical element) of the optical resin material, and a resin amount of HALS for the film-like optical resin material.

  HALS is also preferably used in combination with a benzotriazole-based light-resistant stabilizer. Examples include ADK STAB LA-32, LA-36, LA-31 (manufactured by ADEKA Corporation), Tinuvin 326, Tinuvin 571, Tinuvin 234, Tinuvin 1130 (manufactured by Ciba Japan Co., Ltd.), and the like.

  HALS is preferably used in combination with the various antioxidants. There are no particular restrictions on the combination of HALS and antioxidant, and combinations of phenols, phosphorus, sulfur and the like are possible, but combinations of phosphorus and phenols are particularly preferred.

<Other additives>
Additives applicable to the optical element of the present invention include stabilizers such as heat stabilizers, weathering stabilizers, near infrared absorbers, resin modifiers such as lubricants and plasticizers, in addition to the antioxidants and light stabilizers described above. Examples thereof include: white turbidity inhibitors such as soft polymers and alcoholic compounds; colorants such as dyes and pigments; antistatic agents and flame retardants. These additives can be used alone or in combination of two or more, and the amount added is appropriately selected within a range not impairing the effects described in the present invention.

<< Application field of optical elements >>
The optical composite material of the present invention can be used in various forms such as a spherical shape, a rod shape, a plate shape, a columnar shape, a tubular shape, a tubular shape, a fibrous shape, a film or a sheet shape, Since it is excellent in low birefringence, transparency, mechanical strength, heat resistance, and low water absorption, application to various optical elements is suitable.

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

  Examples of optical disc applications include CD, CD-ROM, WORM (recordable optical disc), MO (rewritable optical disc; magneto-optical disc), MD (mini disc), DVD (digital video disc), and the like. Other optical applications include light guide plates such as liquid crystal displays; optical films such as polarizing films, retardation films and light diffusing films; light diffusing plates; optical cards;

  FIG. 1 is a schematic view showing an example of an optical element (lens made of an optical composite material) according to a preferred embodiment of the present invention.

(Imaging device)
An imaging apparatus 100 as an electronic module has a circuit board 1 on which electronic components constituting an electronic circuit of a mobile information terminal device such as a mobile phone are mounted. The imaging module 2 is mounted on the circuit board 1. Yes. The imaging module 2 is a small board mounting camera in which a CCD image sensor and a lens are combined. In a completed state in which the circuit board 1 on which electronic components are mounted is assembled in the cover case 3, the imaging provided in the cover case 3 is performed. The image to be imaged can be captured through the opening 4 for use.

  As shown in FIG. 2, the imaging module 2 includes a board module 5 and a lens module 6. By mounting the board module 5 on the circuit board 1, the entire imaging module 2 is mounted on the circuit board 1. The substrate module 5 is a light receiving module in which a CCD image sensor 11, which is an electronic component for imaging, is mounted on a sub-substrate 10, and the upper surface of the CCD image sensor 11 is sealed with a resin 12.

  On the upper surface of the CCD image sensor 11, a light receiving portion (not shown) in which a large number of pixels that perform photoelectric conversion are arranged in a grid pattern is formed, and an optical image is formed on the light receiving portion to store each pixel. The charged charges are output as an image signal. The sub-board 10 is mounted on the circuit board 1 by the conductive material 18, thereby fixing the sub-board 10 to the circuit board 1, and connecting electrodes (not shown) of the sub-board 10 and circuit electrodes on the upper surface of the circuit board 1. (Not shown) is electrically connected.

  The lens module 6 includes a lens case 15 that supports the lens 16. A lens 16 is held at the upper part of the lens case 15, and the upper part of the lens case 15 is a holder portion 15 a for holding the lens 16. A lower portion of the lens case 15 is inserted into a mounting hole 10 a provided in the sub-board 10 and serves as a mounting portion 15 b that fixes the lens module 6 to the sub-board 10. For this fixing, a method of pressing and fixing the mounting portion 15b into the mounting hole 10a, a method of bonding with an adhesive, or the like is used.

  The lens 16 is an image pickup element (optical element) used in the image pickup optical system, and is formed of the optical composite material of the present invention.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<Preparation of inorganic particles>
(Preparation of surface-treated zirconia particles)
To a zirconium salt solution in which 2600 g of zirconium oxychloride octahydrate was dissolved in 40 L (liter) of pure water, 340 g of 28% ammonia water and 20 L of diluted ammonia water were added with stirring, to obtain a zirconia precursor. A slurry was prepared.

  Next, an aqueous sodium sulfate solution in which 400 g of sodium sulfate was dissolved in 5 L of pure water was added to the zirconia precursor slurry while stirring.

  Subsequently, this mixture was dried in the air at 120 ° C. for 24 hours using a dryer to obtain a solid.

Next, the solid was pulverized with an automatic mortar or the like and then baked at 500 ° C. for 1 hour in the air using an electric furnace. This fired product is put into pure water, stirred to form a slurry, washed using a centrifuge, sufficiently removed the added sodium sulfate, dried in a drier, and zirconia particles Was prepared. As a result of TEM observation, the average particle size was 5 nm. XRD confirmed that the particles were ZrO ₂ crystals.

  Add 1: 10 g of the above zirconia particles to 100 ml of toluene containing 3 g of each surface treatment agent and use 0.03 mm zirconia beads for 2 hours at a liquid temperature of 20 ° C with a disperser (Ultra Apex Mill, manufactured by Kotobuki Industries). Distributed. Then, the mixture was heated to 100 ° C. with stirring and heated to reflux for 5 hours to obtain a toluene dispersion of each surface-treated zirconia particle. Particles were precipitated from the resulting dispersion by centrifugation to remove unreacted substances in the supernatant, and vacuum-dried at 50 ° C. for 24 hours to obtain surface-treated zirconia powder.

(Preparation of surface-treated alumina particles)
10 g of Daimei Chemical's alumina (TM-300) was dispersed in 500 g of water containing 1 g of ammonia. The disperser was an Ultra Apex mill (manufactured by Kotobuki Kogyo Co., Ltd.), and 0.03 mm zirconia beads were used and dispersed at a liquid temperature of 20 degrees for 2 hours. The obtained particles were dried with a drier and observed with a TEM to confirm that they were alumina particles with an average particle diameter of 7 nm with little aggregation.

  Add 16.7 g of the above alumina particles to 100 ml of toluene containing 3 g of each surface treatment agent, and use 0.03 mm zirconia beads with a disperser (Ultra Apex Mill, manufactured by Kotobuki Industries) at a liquid temperature of 20 degrees. Dispersed for 2 hours. Thereafter, the mixture was heated to 100 ° C. with stirring and heated to reflux for 5 hours to obtain a toluene dispersion of surface-treated alumina particles. Particles were precipitated from the resulting dispersion by centrifugation to remove unreacted substances in the supernatant, and vacuum-dried at 50 ° C. for 24 hours to obtain surface-treated alumina powder.

(Preparation of surface-treated silica)
10 g of silica (A-300) manufactured by Nippon Aerosil Co., Ltd. was dispersed in 500 g of water containing 1 g of ammonia. The disperser was an Ultra Apex mill (manufactured by Kotobuki Kogyo Co., Ltd.), and 0.03 mm zirconia beads were used and dispersed at a liquid temperature of 20 degrees for 2 hours. The obtained particles were dried with a drier and observed with a TEM to confirm that they were silica particles with an average particle diameter of 9 nm with little aggregation.

  Silica particles 1: 3.1 g is added to 100 ml of toluene containing 3 g of each surface treatment agent, 0.03 mm zirconia beads are used, and a dispersion machine (Ultra Apex Mill, manufactured by Kotobuki Industries) is used at a liquid temperature of 20 degrees. Dispersed for 2 hours. Thereafter, the mixture was heated to 100 ° C. with stirring and heated to reflux for 5 hours to obtain a toluene dispersion of surface-treated silica particles. Particles were precipitated from the obtained dispersion by centrifugation to remove unreacted substances in the supernatant, and vacuum-dried at 50 ° C. for 24 hours to obtain surface-treated silica powder.

<Preparation of moldings of Examples 1 to 4, 6, 8, 9 and Comparative Examples 1 to 5>
For the various monomers shown in Table 2, the surface-treated inorganic particles listed in Table 1 were mixed at 30 ° C. using a batch mixer (KF-6V, manufactured by Toyo Seiki Co., Ltd.), then placed in a mold and vacuumed. While being deaerated, while being pressed at 10 MPa, it was heated to 150 degrees to obtain a molded body.

<Example 5>
Using a batch mixer (KF-6V, manufactured by Toyo Seiki Co., Ltd.), the resin and the surface-treated inorganic particles listed in Table 1 were added at the addition amount shown in Table 2 and then melt-kneaded at 180 ° C., and then placed in a mold and vacuumed at 100 ° C. After deaeration, the molded body was obtained by heating to 160 ° C. and pressing to 10 MPa.

<Example 7>
(Preparation of partially fluorinated zirconia particles)
In the preparation of surface-treated zirconia particles, 10 g of an aqueous solution containing 0.4 g of HF is added to 10 g of zirconia particles before the surface treatment, and the mixture is stirred for 12 hours, thoroughly washed with water by centrifugation, dried, and partially fluorinated. Zirconia particles were obtained. A molded body was obtained in the same manner as in Examples 1 to 4 except that these particles were used.

The resins, surface treatment agents and additives shown in Table 1 and Table 2 below are as follows.
(1) Monomer MAF-ADE: 1-adamantyl-α-trifluoromethyl acrylate, manufactured by Tosoh p-F-AdMA: perfluoroadamantyl dimethacrylate, manufactured by Idemitsu Kosan Co., Ltd. DCP: tricyclodecane dimethanol dimethacrylate, manufactured by Shin-Nakamura Chemical Ad-dMA: Adamantyl dimethacrylate, manufactured by Idemitsu Kosan CYTOP: Amorphous fluororesin, manufactured by Asahi Glass (2) Surface treatment agent, additive details KBM-3103: Decyltrimethoxysilane, Shin-Etsu Chemical KBM-503: 3- Methacryloxypropyltrimethoxysilane, Shin-Etsu Chemical KBM-7103: trifluoropropyltrimethoxysilane, Shin-Etsu Chemical fluorine-containing additive: N-propyl-N- (2,3-dihydroxypropyl) perfluorooctanesulfonamide, manufactured by Daikin Pa Royle L: dilauroyl peroxide, made by NOF <optical properties, evaluation of moldability>
(Measurement of refractive index and Abbe number)
The inorganic particles are dispersed in various solvents with adjusted refractive indexes, and the absorbance of the dispersion with respect to light having a wavelength of 589 nm is measured using a spectrophotometer UV-3150 manufactured by Shimadzu Corporation. The refractive index of the inorganic particles was determined by measuring the rate.

  Resin or optical composite material is cured, processed and polished, and using an automatic refractometer (KPR-200, manufactured by Kalnew Optical Industry Co., Ltd.), the refractive index of light with a temperature of 25 ° C. and a wavelength of 589 nm is measured. Or the refractive index of the optical composite material.

  The Abbe number was measured by curing the optical composite material, processing and polishing it, and using an automatic refractometer (KPR-200, manufactured by Kalnew Optical Industry), Fraunhofer C line (656.3 nm), D line (589. 3 nm) and F-line (486.1 nm), the respective refractive indexes, nc, nd, and nf were measured and calculated from the following formula.

Abbe number (νd) = (nd−1) / (nf−nc)
(Measurement of light transmittance)
Using a spectrophotometer UV-3150 manufactured by Shimadzu Corporation, transmittance with respect to light having a wavelength of 589.2 nm was measured. The molded body sample (optical element) was appropriately processed, and the external transmittance so that the optical path length was 3 mm was defined as the transmittance.

(Formability evaluation)
“Crack” was evaluated by visually counting the number of cracks per 1 cm ² of the optical surface.

None: 0
Some: 1 to 3 Many: 4 to 10 Very many: 10 or more When there are many cracks, the measurement accuracy of the light transmittance is particularly lowered, so the transmittance of some samples could not be measured.

  In Table 2, in the optical composite material using alumina, there are many cracks in the molded body. It is considered that the moisture volatilization from the alumina during the heat molding is large and cracks are easily generated inside the molded body.

  As is apparent from the results shown in Table 2, the molded sample for evaluation (optical element) formed from the optical composite material of the present invention has an appropriate refractive index and Abbe number, and excellent moldability and transparency. It can be seen that the material is highly effective as an optical element forming material.

It is a schematic perspective view of the imaging device used by preferable embodiment of this invention. 1 is an enlarged schematic cross-sectional view of a part of an imaging apparatus used in a preferred embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Imaging device 1 Circuit board 2 Imaging module 3 Cover case 4 Imaging opening 5 Substrate module 6 Lens module 10 Sub board | substrate 10a Mounting hole 11 CCD image sensor 12 Resin 15 Lens case 15a Holder part 15b Mounting part 16 Lens 17 Color member 18 Conductivity Material

Claims (4)

An optical composite material composed of an inorganic particle having a refractive index of a light beam having a wavelength of 589 nm of 1.6 or more and a resin, the optical composite material containing 1% by mass or more of fluorine, and a light beam having a wavelength of 589 nm. An optical composite material having a refractive index of 1.48 or more and 1.6 or less and an Abbe number of 55 or more. The optical composite material according to claim 1, wherein the resin has a refractive index of 1.4 or more of light having a wavelength of 589 nm. The optical composite material according to claim 1, wherein the resin is a resin containing 3% by mass to 60% by mass of fluorine. An optical element formed by using the optical resin material according to claim 1.

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