JP2009221350A - Resin composition, its production method, and optical element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of a resin composition which does not foam even at a high temperature and has a low linear expansion coefficient and a high transparency; a resin composition prepared thereby; and an optical element using the composition. <P>SOLUTION: The method produces a resin composition containing core-shell structured inorganic oxide particles in a resin and at least comprises a core particle dispersion process and a silica layer forming process. While maintaining the volume particle dispersion diameter of core particles in a range of 1-100 nm, the silica layer forming process clads the surface of the core particles with a silica layer in a liquid to prepare core-shell structured inorganic oxide particles (hereunder called as core-shell particles), and then the inorganic oxide particles and a resin satisfying the following formula are mixed. The formula is ¾Np-Nm¾<0.005, wherein Np is the flexibility of the core-shell particles, and Nm is the flexibility of the resin. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resin composition, a method for producing the same, and an optical element using the same. Specifically, the present invention relates to a method for producing an optical resin material suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, and the like, and an optical element using the optical resin material.

  Information devices such as a player, a recorder, and a drive for reading and recording information on an optical information recording medium such as MO, CD, and DVD are provided with an optical pickup device. The optical pickup device includes an optical element unit that irradiates an optical information recording 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 converts the light into optical information. It has an optical element such as a lens for condensing light by a reflective layer of a recording medium or a light receiving element. In mounting electronic parts and solid-state image sensor modules, there is a soldering process in which solder is melted in a furnace at a high temperature of about 290 ° C. called reflow. Since plastic lenses do not have heat resistance to withstand the high temperatures of reflow soldering, they are attached after reflow soldering. Therefore, there is a problem that the production efficiency of the assembly is lowered, and a lens having high heat resistance is required from the viewpoint of the efficiency of the assembly. However, when a general thermoplastic resin is used, when a resin having a high glass transition temperature (Tg) that is resistant to heat is used, the molding temperature is high and the molding becomes impossible. Therefore, since the thermosetting resin and the ultraviolet curable resin are liquid at normal temperature and are cured by heat or ultraviolet rays, a resin composition having good thermophysical properties such as Tg after curing can be prepared in advance.

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

  On the other hand, an optical element unit using plastic as a material is required to be a substance having optical stability such as a glass lens. While optical plastic materials have significantly improved refractive index stability with respect to humidity, the current situation is that the improvement in refractive index stability with respect to temperature is not yet sufficient. This is because plastic has an extremely large coefficient of linear expansion with respect to heat compared to glass.

  In contrast, an organic-inorganic composite material in which inorganic fine particles are dispersed in heat or active energy ray-curable resin has been proposed as an optical material having high heat resistance and reduced linear expansion coefficient due to environmental fluctuations. Yes.

  For example, Patent Document 1 proposes an optical element characterized by curing a composition for optical material containing metal oxide fine particles and an organic compound having an unsaturated bond polymerizable with the metal oxide fine particles. Has been. Patent Document 2 proposes a curable resin composition containing core-shell type semiconductor ultrafine particles having a number average particle diameter of 1 to 50 nm, which is composed of a semiconductor crystal core and a metal oxide shell. . Patent Document 3 discloses a polymerizable liquid composition containing an alicyclic ring bis (meth) acrylate and ultrafine particles having a number average of 0.5 to 50 nm as a transparent resin composition excellent in heat resistance and dimensional accuracy. A crosslinked resin composition obtained by polymerizing a product has been proposed.

  However, all of the oxide fine particles used in these resin compositions are contained in the resin after being shell-formed or surface-treated without being fired. Therefore, in these resin compositions, the oxide fine particles themselves contain many hydroxyl groups and containing solvents, and large foaming is observed at high temperatures. As a result, in the reflow process, all foamed and could not be used. On the other hand, when conventionally dried particles are contained in a resin, it is difficult to disperse by the dry aggregation, and it is difficult to produce a transparent resin composition.

Patent Document 4 discloses a transparent composition in which silica is formed on the surface of an inorganic oxide, and the surface hydroxyl group of the heat-treated surface is 9 × 10 ⁻⁶ / m ² or less, and the refractive index of the core / shell particles is close to the refractive index of the epoxy resin. Has been proposed.

  However, in order to obtain a higher transmittance, particles having a particle diameter of 30 nm or less must be used. However, as the specific surface area rapidly increases, fusion due to heating occurs and the particle cannot be used.

Further, in the silica formation stage, uniform treatment becomes difficult, and white turbidity occurs due to the accompanying spread of the refractive index distribution.
Japanese Patent Laid-Open No. 2005-3772 JP 2003-155415 A Japanese Patent Laid-Open No. 2007-126585 JP-A-6-65475

  The present invention has been made in view of the above-described problems and circumstances, and a solution to the problem is a resin having no foaming even at a high temperature, low refractive index temperature dependency (dN / dT), and high transparency. It is providing the manufacturing method of a composition, the obtained resin composition, and also an optical element using the same.

  The inventor of the present invention has made low temperature dependence (dN / dT) of foaming and refractive index, and as a result of intensive studies to solve the problems of transparency and particle fusion, dried particles have a volume average particle diameter of 1 to 100 nm. By forming a silica layer on the surface in a dispersed and retained state, core / shell particles having an extremely low refractive index distribution could be produced, and further, there was no aggregation during drying in a subsequent step. The resin composition using the core / shell particles does not show high-temperature foaming because the particles that have undergone the drying step are core particles, and the refractive index of the core / shell particles is close to the refractive index of the resin. The inventors have found that a transparent resin composition exhibiting high transparency can be formed because the refractive index distribution is narrow, and the present invention has been achieved.

  That is, the said subject which concerns on this invention is solved by the following means.

1. A method for producing a resin composition containing inorganic oxide particles having a core / shell structure in a resin, comprising at least a core particle dispersing step and a silica layer forming step, wherein in the silica layer forming step, the volume of the core particles While maintaining the particle dispersion diameter at 1 to 100 nm, the surface of the core particles in the liquid is coated with a silica layer to form inorganic oxide particles having a core / shell structure (hereinafter referred to as “core / shell particles”). The manufacturing method of the resin composition characterized by mixing the said inorganic oxide particle and resin which satisfy | fills the following conditional expression.
Conditional expression: | Np−Nm | <0.005
In the formula, Np: refractive index of core / shell particles, Nm: refractive index of resin. Before coating the surface of the core particles with a silica layer, 100% by mass or less of a silica precursor is added to and dispersed in the core particles, so that the volume particle dispersion diameter of the core particles is 1 to 100 nm. 2. The method for producing a resin composition as described in 1 above.

  3. A resin composition produced by the method for producing a resin composition as described in 1 or 2 above.

4). 4. The resin composition as described in 3 above, wherein the resin composition satisfies the following conditional expression.
Conditional expression: Nd <0.01
However, Nd: Core-shell particle refractive index distribution 5. An optical element produced using the resin composition as described in 3 or 4 above.

  By the above-mentioned means of the present invention, there is no foaming even at a high temperature, the temperature dependency of the refractive index (dN / dT) is low, a method for producing a resin composition having high transparency, and the obtained resin composition, An optical element using the same can be provided. That is, by the above means, there is no foaming even at a high temperature, and the temperature dependence (dN / dT) of the refractive index is low, and the optical element that maintains transparency, the imaging optical system using the optical element, the imaging module, the light An optical system for a pickup device, an optical pickup device, an electronic module, and a manufacturing method thereof can be provided.

The method for producing a resin composition of the present invention is a method for producing a resin composition containing inorganic oxide particles having a core / shell structure in a resin, and includes at least a core particle dispersing step and a silica layer forming step, In the silica layer forming step, the surface of the core particle is covered with a silica layer in a liquid while maintaining the volume particle dispersion diameter of the core particle at 1 to 100 nm. -Shell particles "), and then the inorganic oxide particles and a resin satisfying the following conditional expression are mixed.
Conditional expression: | Np−Nm | <0.005
However, in the formula, Np: refractive index of core / shell particles, Nm: refractive index of resin The above characteristics are technical characteristics common to the inventions according to claims 1 to 5.

  As an embodiment of the present invention, before coating the surface of the core particles with a silica layer, 100% by mass or less of a silica precursor is added to and dispersed in the core particles, whereby the volume particles of the core particles are It is preferable that the dispersion diameter is 1 to 100 nm.

The resin composition produced by the method for producing a resin composition of the present invention is preferably prepared so as to satisfy the following conditional expression.
Conditional expression: Nd <0.01; However, Nd: Core-shell particle refractive index distribution By satisfy | filling the said conditions, the said resin composition can be used suitably for an optical element.

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

(Outline of production method of resin composition of the present invention)
The method for producing a resin composition of the present invention is a method for producing a resin composition containing inorganic oxide particles having a core / shell structure in a resin, and includes at least (1) a core particle dispersion step and (2) a silica layer. And forming a core particle dry powder of inorganic oxide particles in a solvent in the core particle dispersion step, and in the silica layer forming step, the volume particle dispersion diameter of the core particles is 1 nm or more and 100 nm or less. While maintaining the liquid, the surface of the core particles in the liquid is coated with a silica layer to form core-shell structure inorganic oxide particles (hereinafter referred to as “core-shell particles”), and then the silica layer forming step or the next step Therefore, it is necessary that the inorganic oxide particles are mixed with a resin that satisfies the following conditional expression.

  Hereinafter, each component etc. will be described in detail.

(Core particles)
The inorganic oxide fine particles as the core particles according to the present invention can be produced by any means such as a plasma method, a flame method, and a wet method, but in the present invention, the production process of the core particles themselves is not problematic. The particles that have undergone the drying step are used as the core particles. The drying step in this patent refers to a step of annealing at a temperature equal to or higher than the boiling point of the solvent to remove the solvent. In particular, annealing at a temperature of 250 ° C. or higher is preferable from the viewpoint of preferably removing volatile components contained in the particles. Particles that are exposed to high heat of several thousand degrees in a particle production process such as a flame method or a plasma method can be regarded as being dried. Since these particles have undergone a drying step, the core / shell particles prepared using these particles as core particles hardly show foaming at high temperatures. Accordingly, a resin composition containing core / shell particles produced using particles that have undergone a drying process as core particles is preferable because foaming at high temperatures is not observed.

  The core particles preferably used in the present invention have an average primary particle diameter of 1 nm or more and 20 nm or less, and more preferably 1 nm or more and 10 nm or less. If the average primary particle size is less than 1 nm, it is difficult to disperse the core particles and the desired performance may not be obtained. Therefore, the average primary particle size is preferably 1 nm or more, and the average primary particle size is If it exceeds 20 nm, the resulting resin composition may become cloudy and the transparency may be reduced, and the light transmittance may be less than 70%. Therefore, the average primary particle diameter is preferably 20 nm or less. The average primary particle diameter here refers to the volume average value of the diameter (sphere equivalent particle diameter) when each primary particle is converted to a sphere having the same volume.

  Further, the core particles are composed of metals such as Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, One or more selected from the group consisting of Nb, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi and rare earth metals Inorganic oxide fine particles that are metals such as titanium oxide, zinc oxide, aluminum oxide, zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, magnesium oxide, calcium oxide, strontium oxide can be used. , Barium oxide, indium oxide, tin oxide, lead oxide, and double oxides such as lithium niobate, potassium niobate, and lithium tantalate , Magnesium aluminum oxide (MgAl2 O4), and the like. In addition, rare earth oxides can also be used as oxide fine particles used in the present invention, 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. Especially, since the refractive index of general curable resin is about 1.5-1.6, it is preferable to use aluminum oxide from the point that the refractive index adjustment to curable resin is easy. Furthermore, it is also preferable for the optical element and filler to have a high Abbe number. Aluminum oxide has an isoelectric point on the basic side, so it is difficult to stably disperse in basic, and silica coating is difficult and difficult to use, but by using the method of this patent, it is preferably dispersed in a solution, A silica coat can be used.

(Production of core / shell particles)
The core / shell particle production process according to the present invention is divided into at least (1) a core particle dispersion process and (2) a silica layer formation process.

  In the present invention, the silica layer forming step is characterized in that the core particles are maintained within a range of 1 to 100 nm by a volume average particle meter. According to the study by the present inventors, the particle diameter calculated from the specific surface area and specific gravity of the particles measured by specific surface area measurement (BET method), and the average primary particle diameter of the core particles observed with a transmission electron microscope (TEM) Regardless, the state of aggregation of the core particles in the dispersion at the silica layer formation stage is measured by the dynamic light scattering method, and the average particle diameter of the volume fraction of the measured particle diameter (hereinafter referred to as “volume average particle diameter”). Therefore, the transparency of the resin composition is determined, and in order to maintain the transparency in the visible light region, the dispersion is maintained at a volume average particle diameter of 1 to 100 nm, which is a region where scattering is extremely small. There is a need. Furthermore, by passing through this step, the refractive index distribution for each core / shell particle can be made extremely small, and a resin composition having high transparency can be obtained when the core / shell particles are contained in the resin. Core / shell particles capable of being formed can be obtained.

(1) Core particle dispersion | distribution process A dispersion | distribution process is based on the dispersion | distribution method in wet processing. In this dispersion method, a dispersion apparatus in wet processing is applied. As the dispersing device, a medium stirring mill such as an ultrasonic disperser or a bead mill is applicable, and among these, a bead mill is preferably used.

  When a bead mill is applied as a dispersing device, beads are filled as a medium in the container, and the core particles and the solvent are poured into the container while stirring the beads, and these particles are further stirred in the container, whereby the particles are contained in the solvent. To disperse. At that time, the dispersion can be stabilized by adding a silica precursor or a dispersant. In some cases, the dispersant causes deterioration of heat resistance in the resin composition, and therefore, it is preferable to perform dispersion using only the silica precursor.

  Specific examples of the apparatus when a bead mill is used as the dispersing apparatus include Star Mill ZRS (manufactured by Ashizawa Finetech Co., Ltd.), Ultra Apex Mill (manufactured by Kotobuki Industries Co., Ltd.), and the like.

  As the beads, glass, alumina, steel, diamond, flint stone and the like are applicable, and it is preferable to apply zirconia powder (for example, TZ series (manufactured by Tosoh Corporation)). Moreover, it is preferable to apply what has a particle diameter of about 0.015-0.3 mm as a bead.

  As the dispersant, a commercially available one can be arbitrarily used.

  As the silica precursor, tetramethoxysilane, tetraethoxysilane, tetramethoxytitanium, tetraethoxytitanium, sodium silicate and the like are applicable, but not limited thereto. As the precursor compound, any reagent can be used as long as it hydrolyzes the surface of the core particles to form silica. In particular, it is preferable to use tetraethoxysilane, which hardly generates an aggregate of inorganic particles and has high dispersibility. The silica precursor is preferably 20 to 60% by mass with respect to the particles. 40-50 mass% is more preferable from the high dispersion stability of the particle | grains after dispersion | distribution. These silica precursors are desirably added gradually during dispersion with a disperser. It is desirable to add continuously at 5 to 10% by mass / h with respect to the particles.

  In the present invention, the particle dispersion diameter after dispersion is desirably 1 to 100 nm in terms of volume average particle diameter, and more desirably 60 nm to 1 nm. In a dispersion liquid of 100 nm or more, the refractive index distribution (Np) of the silica-coated inorganic oxide fine particles may be large and the transparency in the resin may be impaired. The volume average particle diameter can be arbitrarily measured with a measuring instrument using a dynamic light scattering method such as Zetasizer HSa (Sysmex Corporation). The concentration of the core particles at the time of dispersion is preferably 3 to 20% by mass from the viewpoint of productivity, dispersibility, and the like. More desirably, it is 3 to 10% by mass.

  Solvents used in the wet treatment include pure water, methanol, ethanol, isopropyl alcohol, ethoxyethanol, dimethylformamide, acetone, ethyl acetate, tetrahydrofuran, benzene, toluene, hexane, xylene, cyclohexane, and other inorganic particles. Depending on the dispersibility and stability of the precursor, the characteristics of the precursor compound, or the dispersant, etc., these can be used alone or in combination of two or more. As the solvent, it is preferable to use pure water because it is easy to handle and inexpensive. The pH in the reaction solution is preferably pH 9-13. A pH of 9 to 11 is more preferred from the viewpoint of particle stability. As a reagent for adjusting pH, ammonia, ammonium acetate, ammonium hydrogen carbonate, ammonium carbonate, trimethylamine, pyridine, aniline, and the like can be preferably used. However, ammonia can be used because it can be easily removed by heating after particle formation. preferable.

(2) Silica layer forming step In the layer forming step, a silica precursor compound is added to the dispersion obtained in the dispersing step, and the dispersion is stirred. During the step of dropping the precursor, the dispersed particles must be dispersed and must be dispersed with a volume average particle size of 1 to 100 nm, more preferably 1 to 60 nm. When the volume average particle diameter is larger than this, the silica layer to be formed becomes non-uniform and cannot be practically used.

  The volume average particle size can be arbitrarily measured with a particle size measuring instrument such as Zetasizer HSa (Sysmex Corporation).

  Furthermore, it is desirable to dilute the dispersion in the previous step using an arbitrary organic solvent and pure water in the previous step of the precursor dropping step. It is preferable to adjust the particle concentration to 0.3 to 5% by mass by this dilution. In view of dispersion stability, the content is desirably 0.3 to 1% by mass. As the organic solvent used, methanol, ethanol, t-butanol, acetonitrile and the like can be preferably used, and it is desirable to use ethanol from the viewpoint of handling and environmental suitability. It is desirable to adjust to a 40 to 80 mass% aqueous solution by adding an organic solvent and pure water at an arbitrary ratio to the dispersion. It is desirable that it is 50-70 mass% from the surface of the uniformity of the silica formed.

  Furthermore, the reaction solution must be adjusted to pH 9-12. From the viewpoint of the stability of the dispersed particles, a pH of 10 to 11 is more preferable. As a reagent for adjusting pH, ammonia, ammonium acetate, ammonium hydrogen carbonate, ammonium carbonate, trimethylamine, pyridine, aniline, and the like can be preferably used. However, ammonia can be used because it can be easily removed by heating after particle formation. preferable.

  In addition, in order to accelerate | stimulate reaction in a stirring solution, you may heat a stirring solution arbitrarily. The heating temperature is preferably 5 to 60 ° C, more preferably 20 to 40 ° C. When the heating temperature exceeds 60 ° C., phenomena such as formation of single particles of the precursor compound and volatilization of the solvent may occur, which is not preferable. On the other hand, if the heating temperature is less than 5 ° C., the reaction time in the stirring solution is prolonged, and this is not preferable for practical use. It is preferable that the silica precursor is continuously dropped at a rate of 60% by mass / h or less with respect to the particles in the solution. More desirably, it is 40 mass% / h or less. When added at a faster rate, the dispersion stability of the particles may be lost. In order to maintain transparency by including core / shell particles in the resin composition, it is necessary to disperse in the liquid in the region of ultrafine particles having a volume average particle diameter of 1 to 100 nm in which scattering is extremely small, and to cover the surface with silica. However, the cohesive force increases as the dispersibility decreases, and it is extremely difficult to form a silica layer while maintaining the particle diameter at a volume average particle diameter of 1 to 100 nm.

  In the present invention, it was newly found from the inventors' investigation that the stability of the particles in the silica layer forming step is determined by the concentration of the particles, the addition rate of the silica precursor, the concentration of the organic solvent, and the solution pH. Therefore, in the present invention, by examining these factors and finding the optimum range, this series of steps, in which the particles were held at a volume average particle diameter of 1 nm to 100 nm and a silica layer was successfully formed, It has been surprisingly found that the core-shell particle refractive index distribution (Nd) becomes extremely low. After the silica precursor is dropped, a silica layer is formed after a ripening period of 24 hours after the completion of dropping the silica precursor. In the core / shell particle dispersion prepared in these steps, the core / shell particles are preferably dispersed in a volume average particle diameter of 1 nm to 100 nm. More preferably, it is desirable to stably disperse to 1 to 60 nm. By forming silica in a stably dispersed state, silica can be formed extremely uniformly on the surface of the particles, and the refractive index distribution (Np) of the core-shell particles can be reduced. In particular, by using only the silica precursor at the time of dispersion, the reagent to be added is only the silica precursor in the production process, and when the resin composition is formed, the linear expansion and coloring are adversely affected. More preferable core / shell particles containing no organic substance such as a dispersing agent can be produced.

(Core / shell particles)
The core / shell particles according to the present invention are particles that can be taken out from the core / shell particle dispersion by drying such as freeze drying, spray drying, and supercritical drying. The core-shell particles thus obtained are formed by forming silica on the surface of the core particles, and the average primary particle diameter is 1 nm or more and 30 nm or less, preferably 1 nm or more and 20 nm or less, more preferably 1 nm or more, 10 nm or less. When the average primary particle size is less than 1 nm, it is difficult to disperse the core / shell particles in the resin and the desired performance may not be obtained. Therefore, the average primary particle size is preferably 1 nm or more, From the viewpoint of light transmittance, the average primary particle diameter is preferably 30 nm or less.

  The “average primary particle diameter” here refers to the volume average value of the diameter (sphere converted particle diameter) when each primary particle is converted to a sphere having the same volume.

  Further, the shape of the core / shell 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.

  Furthermore, the core-shell particles have a refractive index distribution depending on the thickness of the silica layer on the surface and the particle size distribution of the used core particles. The refractive index distribution is measured by confirming the particles with a TEM (transmission electron microscope), quantifying the elements of Si and core particles with a plurality of particles using an EDX (energy dispersive X-ray detector), From the results, the quantitative ratio of the elements of silica and core particles is obtained, the refractive index is calculated, and the standard deviation of the refractive index of the core-shell particles is obtained. This is the core-shell particle refractive index distribution (Nd).

In the present invention, the transparency is ensured by making the refractive index of the core / shell particles close to the refractive index of the resin, but the transparency is improved by further reducing the refractive index distribution of the core / shell particles themselves. . Nd of the silica core according to the present invention is extremely low by maintaining the particles at a volume average particle diameter of 100 nm or less when forming the silica layer, but in terms of high transparency,
Nd <0.01
It is desirable to satisfy.

Furthermore, the particles are similarly confirmed with a TEM (transmission electron microscope), and the elements of Si and core particles are quantified with respect to a plurality of particles with an EDX (energy dispersive X-ray detector). The quantity ratio of the elements of silica and core particles is determined, and the average refractive index is calculated from this value. This is the refractive index (Np) of the core-shell particles according to the present invention. The refractive index (Np) of the core-shell particle according to the present invention is determined by the refractive index and volume% of the core particle, and can be arbitrarily adjusted by controlling the thickness of the silica layer with respect to the core particle. Especially in terms of high transparency, the refractive index (Nm) of the resin
| Np-Nm | <0.005
Must be met. By making the core / shell particle refractive index Np close to the refractive index (Nm) of the resin, a resin composition exhibiting high transparency can be obtained without completely eliminating particle aggregation in the resin.

  In the present invention, the interparticle distribution of the particle composition can be determined using an electron probe microanalyzer, a scanning transmission analytical electron microscope, or the like.

  In this invention, it is preferable to obtain | require by the method (STEM-EDX) which combined the scanning transmission electron microscope and energy dispersive X-ray-spectroscopy analysis from particle size.

  For example, the composition distribution measurement between particles using STEM-EDX is specifically performed by the following procedure.

(1) Sample preparation <For powder>
2 ml of ethanol was placed in a micro test tube, and the particles were placed therein, and dispersed by irradiating ultrasonic waves with an ultrasonic disperser. Using a micropipette, a particle dispersion was dropped onto a grid mesh with a hydrophilic high-resolution carbon support film and dried to prepare a sample.

  The concentration of the particles in the dispersion was such that each particle was observed independently when observed with a transmission electron microscope.

<For composite>
An ultrathin section of the kneaded material was prepared with an ultramicrotome, collected on a microgrid, and used as a sample. The thickness of the ultrathin section is preferably 100 nm or less. This time, an ultrathin section having a thickness of 80 nm was prepared.

(2) Measurement The composition distribution between particles was measured using a transmission electron microscope (JEM2010F manufactured by JEOL Ltd.) and an energy dispersive X-ray spectroscopic analyzer (PIONEER type detector and VANTAGE digital microanalysis system manufactured by NORAN). The acceleration voltage of the transmission electron microscope is preferably 200 kV. The magnification can be adjusted as appropriate. This time, it was measured at 50,000 times. After adjusting the axis of the electron microscope, observe in scanning transmission mode, and after confirming that the particles are properly dispersed, use the software (VISTA made by NORAN) for the elements XX and XX. Get element map. The resolution of the element map can be adjusted as appropriate, but is preferably 256 × 256 pixels or higher. The measurement time was integrated until the X-ray peak of the minor component element obtained from one particle reached 200 counts or more.

(3) Calculation of interparticle composition distribution The X-ray peak intensity of the elements constituting each particle is obtained from the obtained element map. For the peak intensity, an X-ray spectrum is extracted by setting one particle as one area while confirming a scanning transmission image of each particle from the element map previously acquired on the software used for measurement.

  The elemental composition of each particle is calculated using the X-ray intensity of each area and the sensitivity coefficient previously obtained from the standard sample. The particle composition is preferably at least 100 points, preferably 300 points or more for each sample, and the composition of each particle is preferably determined.

(Hydrophobic treatment)
It is desirable that the core / shell particles have a hydrophobic surface in order to improve wettability with the resin. In the hydrophobization process according to the present invention, both dry and wet processes can be used.

  In the dry hydrophobization treatment, the solvent is changed to water, t-butanol, etc. by using ultrafiltration or the like from the dispersion liquid that has undergone the layer formation step, and then the core / shell is freeze-dried or spray-dried, centrifuged, filtered, etc. Separate the particles from the solvent. Thereafter, the core / shell particles are dried or dried under reduced pressure in the range of 80 to 120 ° C. to remove the residual solvent, and optionally aged in the range of 200 to 400 ° C. When coloring is observed during the aging operation, aging is preferably performed while flowing an inert gas such as nitrogen or argon. After adding the hydrophobizing agent to the particles by dropping or spraying the particles obtained in a high-speed stirrer such as a Henschel mixer or a super mixer while adding the hydrophobizing agent to the particles. Heat the powder.

  In the wet hydrophobization treatment, the core / shell particles separated by the above method are put into a solvent, and the surface is hydrophobized by adding a hydrophobization treatment agent. As the solvent, THF, acetonitrile, dioxane, dimethylformamide, dimethyl sulfoxide and the like can be preferably used.

  As the hydrophobizing agent, it is preferable to use a silane coupling agent exhibiting heat resistance and high hydrophobicity. Silane coupling agents include hexamethyldisilazane, trimethylethoxysilane, trimethylmethoxysilane, trimethylsilyl chloride, methyltriethoxysilane, dimethyldiethoxysilane, decyltrimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxy. Silane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, SZ6187 manufactured by Toray Dow Silicone, and the like can be suitably used.

  Among the above silane coupling agents, it is preferable to use a monofunctional silane coupling agent since the aggregation of particles in the liquid is small. Furthermore, as the particle size is reduced, the surface area relative to mass increases, and when a hydrophobic treatment is performed using a hydrophobic treatment agent having a large molecular weight, a large amount of the hydrophobic treatment agent is required. The physical properties of an optical resin material produced using particles containing a large amount of hydrophobic treatment deteriorate. Therefore, it is desirable to use a silane coupling agent having a small molecular weight and high hydrophobicity, and it is more preferable to use hexamethyldisilazane, trimethylethoxysilane, trimethylmethoxysilane, or trimethylsilyl chloride as the hydrophobizing agent.

  The addition amount of the hydrophobizing agent is preferably 50 to 400% by mass with respect to the total core / shell particles.

(Drying process)
It is desirable that the core / shell particles after hydrophobization be dried in some cases. In particular, when the surface treatment is performed in a wet manner, the core / shell particles can be taken out from the liquid by centrifugation or filtration, and drying using an oven or the like can be used.

  The oven drying temperature is preferably 100 ° C. to 200 ° C. from the viewpoint of particle aggregation, combustion of the surface treatment agent, and the like. More preferably, it can heat in the range of 100 to 150 degreeC.

  Furthermore, freeze drying and supercritical drying are more preferable from the viewpoint of dry aggregation of particles in the solvent. Freeze drying is preferable from the viewpoint of cost. When lyophilization is used, it is preferable to add a surface treatment agent to the dispersion liquid after the silica layer forming step, perform surface treatment in the liquid, replace with t-butanol by ultrafiltration, and freeze-dry. After lyophilization, it can optionally be heated. It is preferable to heat at 100 to 200 ° C. More preferably, it can heat in the range of 100 to 150 degreeC.

(resin)
In the resin composition of the present invention, both a thermoplastic resin and a curable resin can be used, but a thermosetting resin can be preferably used. The curable resin preferably contains at least one compound having a polyfunctional alicyclic hydrocarbon skeleton having two or more reactive groups.

  A resin composition obtained by curing a transparent curable compound having a polymerization reactive group such as a (meth) acryl group has been used as an optical material used in an optical system of a spectacle lens or various optical instruments. In order to ensure the reliability of advanced physical properties against environmental fluctuations, which are required for optical elements used in various optical instruments, there are problems such as insufficient heat resistance and a large coefficient of linear expansion. is there. On the other hand, the curable composition containing at least one compound having a polyfunctional alicyclic hydrocarbon skeleton having two or more reactive groups is obtained by uniformly dispersing inorganic fine particles and polymerizing and curing them. It was found that excellent heat resistance was exhibited while ensuring transparency.

  In addition, both a compound having a polyfunctional alicyclic hydrocarbon skeleton having two or more reactive groups and a compound having a monofunctional alicyclic hydrocarbon skeleton having one reactive group are included. It has been found that an optical element comprising a curable composition and inorganic fine particles exhibits higher transparency and lower hygroscopicity in addition to excellent heat resistance.

(Polycyclic hydrocarbon compounds)
As the compound having an alicyclic hydrocarbon-based skeleton used in the present invention, those having an aliphatic polycyclic structure and including a three-dimensional cross-linked structure are preferable, and particularly preferable compounds include the following general formula ( 1), for example, tricyclodecane dimethanol dimethacrylate, tricyclodecane dimethanol diacrylate, compounds represented by the following general formula (2), for example, adamantyl methacrylate, adamantyl acrylate, etc. Examples of the compound represented by the general formula (3) include isobornyl methacrylate, isobornyl acrylate, and vinyl norbornene.

  In addition, an aliphatic polycyclic structure has ring-opening reactivity, and a denser cross-linked structure can be formed by adding a polyfunctional compound capable of reacting with this, but such a reaction is possible. Examples of the compound include compounds represented by the following general formula (4). Specifically, acrylic acid (6-ethyltricyclo [2,2,1,02,6] -3-heptyl) ester, methacrylic acid ( 6-ethyltricyclo [2,2,1,02,6] -3-heptyl) ester and the like.

  These can be produced by the method disclosed in JP-A-7-18897. As described in the above-mentioned publication, this compound has a tricyclo [2,2,1,02,6] -3-heptane ring so that an active hydrogen atom such as a hydroxyl group, a carboxyl group, or a mercapto group can be present. Since the ring-opening reaction occurs in the presence of the compound to be contained, the addition of this as a cross-linking agent improves the cross-linking density, and a cured product having high temperature durability can be obtained. In forming a crosslinked structure by this ring-opening reaction, the reaction can be accelerated by adding a ring-opening reaction catalyst to the polymerization curable composition. Examples of such a catalyst include aluminum acetylacetonate, palladium acetate. Dibutyltin laurate or the like can be used.

  These polycyclic hydrocarbon compounds may be used alone or in combination of two or more when the resin composition is formulated.

(In the general formula (1), X represents a group represented by —CH ₂ —O—CO—CHR ₁ ═CH ₂ , and R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. )

(In the above general formula (2), Y is represented by —O—CO—CHR ₁ ═CH ₂ , —CO—R ₂ —CHR ₁ ═CH ₂ , or —O—R ₂ —CHR ₁ ═CH _2. R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a single bond, a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, and R ₃ and R ₄ each independently A hydrogen atom and a C1-C10 hydrocarbon group are represented, and m represents an integer of 1-3.)

(In the general formula (3), Z is a group represented by _{-O-CO-CHR 1 = CH} 2 or -CHR ₁ = CH _2,, A is a single bond or a carbon - carbon double bonds R ₁ represents a hydrogen atom or a methyl group, and R _{5 to} R ₇ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.)

(In the general formula (4), W is a group represented by —O—CO—CHR ₁ ═CH ₂ , R ₁ represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ₈ and R ₉ represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.)
In the resin composition of the present invention, in addition to the compound having the alicyclic hydrocarbon skeleton, it reacts with these compounds and inorganic fine particles having a reactive group to form a crosslinked structure in the resin. A suitable compound can be included. Moreover, a thermal polymerization initiator, a photopolymerization initiator, a stabilizer, a surfactant, and the like can be included as appropriate.

(Polyfunctional compound)
The polyfunctional compound used in the present invention is a compound having two or more reactive groups such as a vinyl group, a (meth) acryloyl group, an epoxy group, an oxetanyl group, a mercapto group, and the like. It reacts with inorganic fine particles having a reactive compound and a reactive compound to form a crosslinked structure in the resin.

  For example, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, tetraethylene glycol diacrylate, diethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane triacrylate having two or more (meth) acryloyl groups as polyfunctional (meth) acrylate Methacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate and the like are polyfunctional epoxy compounds, glycidyl ether type epoxy resins such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, resorcinol diglycidyl ether, diglycidyl phthalate, and Dimer acid diglycidyl ester, triglycidyl ether trif Nylmethane, tetraglycidyl ether tetraphenyl ethane, bisphenol S diglycidyl ether, cresol novolac glycidyl ether, triglycidyl isocyanurate, tetrabromobisphenol A diglycidyl ether, etc., as polyfunctional oxetane compounds, reaction of polyfunctional phenolic compounds with oxetane chloride Products, for example, bifunctional oxetane compounds such as bisphenol A type, bisphenol F type, bisphenol S type, biphenyl type and cardo type, trifunctional oxetane compounds such as trisphenol methane type and triskresol methane type, phenol novolac type, cresol Examples thereof include polyfunctional oxetane compounds such as novolak type and calixarene type.

  These polyfunctional compounds may be used not only in the resin composition but also in combination of two or more.

  The addition amount of the polyfunctional compound is preferably 1 to 80 parts by mass, and more preferably 5 to 60 parts by mass with respect to 100 parts by mass of the curable composition.

(Thermal polymerization initiator)
In the present invention, a thermal polymerization initiator such as a thermal radical generator can be added as necessary. Examples of the thermal polymerization initiator used here include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4- Azo compounds such as methoxy-2,4-dimethylvaleronitrile), organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butylperoxypivalate, 1,1′-bis (t-butylperoxy) cyclohexane, etc. It is done.

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

(Stabilizer)
In the resin composition according to the present invention, one or more stabilizers selected from hindered amine stabilizers, phenol stabilizers, phosphorus stabilizers, and sulfur stabilizers may be additionally added. . By appropriately selecting these stabilizers and adding them to the plastic optical element material, for example, the white turbidity when continuously irradiating light with a short wavelength such as 400 nm, and the optical characteristic fluctuations such as the refractive index fluctuations can be enhanced. Can be suppressed.

  As a preferable phenol-based stabilizer, conventionally known ones can be used, for example, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2 , 4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate and the like, and JP-A Nos. 63-179953 and 1-168643. Acrylate compounds described in Japanese Patent Publication No. 1; octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2′-methylenebis (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 [ie pentaerythrmethyl- Tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenylpropionate))], triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate) Alkyl-substituted phenolic compounds such as 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 compound; and the like.

  Preferred hindered amine stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis ( 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-benzyloxy-2, 2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6) -Pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1-acryloyl-2,2,6 6-tetramethyl-4-piperidyl) 2,2-bis (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6-pentamethyl) -4-piperidyl) decandioate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy]- 1- [2- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- (2 , 2,6,6-tetramethyl-4-piperidyl) amino-N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide and the like.

  Further, the preferable phosphorus stabilizer is not particularly limited as long as it is usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonyl) Phenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9 Monophosphite compounds such as 1,4-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 4,4'-butylidenebis (3-methyl-6-tert-butylphenyl-di-tridecyl phosphite ), 4,4'-isopropylidenebis (phenyl-di-alkyl (C12-C15) phosphine) Ito) 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.

  Further, preferable sulfur stabilizers include, for example, dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3- Thiodipropionate, pentaerythritol-tetrakis (β-laurylthio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, etc. It is done.

  Although the compounding quantity of these stabilizers is suitably selected in the range which does not impair the objective of this invention, it is 0.01-2 mass parts normally with respect to 100 mass parts of resin compositions, Preferably it is 0.01-1 mass. Part.

(Surfactant)
A surfactant is a compound having a hydrophilic group and a hydrophobic group in the same molecule. The surfactant prevents white turbidity of the plastic optical element material by adjusting the rate of moisture adhesion to the resin surface and the rate of moisture evaporation from the surface.

  Specific examples of the hydrophilic group of the surfactant include a hydroxy group, a hydroxyalkyl group having 1 or more carbon atoms, a hydroxyl group, a carbonyl group, an ester group, an amino group, an amide group, an ammonium salt, a thiol, a sulfonate, and phosphoric acid. Examples thereof include a salt and a polyalkylene glycol group. Here, the amino group may be primary, secondary, or tertiary. Specific examples of the hydrophobic group of the surfactant include an alkyl group having 6 or more carbon atoms, a silyl group having an alkyl group having 6 or more carbon atoms, and a fluoroalkyl group having 6 or more carbon atoms. Here, the alkyl group having 6 or more carbon atoms may have an aromatic ring as a substituent. Specific examples of the alkyl group include hexyl, heptyl, octyl, nonyl, decyl, undecenyl, dodecyl, tridecyl, tetradecyl, myristyl, stearyl, lauryl, palmityl, cyclohexyl and the like. Examples of the aromatic ring include a phenyl group. This surfactant only needs to have at least one hydrophilic group and one hydrophobic group as described above in the same molecule, and may have two or more groups.

  More specifically, examples of such surfactants include myristyl diethanolamine, 2-hydroxyethyl-2-hydroxydodecylamine, 2-hydroxyethyl-2-hydroxytridecylamine, 2-hydroxyethyl-2- Hydroxytetradecylamine, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, di-2-hydroxyethyl-2-hydroxydodecylamine, alkyl (8-18 carbon atoms) benzyldimethylammonium chloride, ethylene Examples thereof include bisalkyl (carbon number 8 to 18) amide, stearyl diethanolamide, lauryl diethanolamide, myristyl diethanolamide, palmityl diethanolamide, and the like. Among these, amine compounds or amide compounds having a hydroxyalkyl group are preferably used. In the present invention, two or more of these compounds may be used in combination.

  The surfactant is added in an amount of 0.01 to 10 parts by mass with respect to 100 parts by mass of the plastic optical element material. When the addition amount of the surfactant is less than 0.01 parts by mass, it is not possible to effectively suppress white turbidity of the molded product due to fluctuations in temperature and humidity. On the other hand, when the addition amount exceeds 10 parts by mass, the light transmittance of the molded product becomes low, and application to the optical pickup device becomes difficult. The addition amount of the surfactant is preferably 0.01 to 5 parts by mass and more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the resin composition.

(Production method of resin composition)
The resin composition comprising a curable resin used in the present invention can be cured by either ultraviolet or electron beam irradiation or heat treatment, and the curable resin and core / shell particles are in an uncured state. By mixing and curing, the resin composition of the present invention is obtained.

  For mixing the curable resin with the core / shell particles, an appropriate method can be adopted. For example, the curable resin and the core / shell particles are mixed using a mortar, a rotation / revolution mixer, a dissolver mixer, or the like. After mixing in advance, it is preferable to sufficiently disperse the core / shell particles by supplying sufficient energy using various kneaders.

  Examples of the kneading apparatus include a closed kneading apparatus such as a lab plast mill, a Brabender, a Banbury mixer, a kneader, and a roll, or a batch kneading apparatus. Moreover, it is also possible to manufacture using a continuous melt-kneading apparatus such as a single-screw extruder or a twin-screw extruder.

  Since the core-shell particles according to the present invention not only have a small refractive index distribution, but also have a volume average particle meter kept at 5 to 100 nm, silica is uniformly formed on the surface. High nature.

  In the method for producing a resin composition according to the present invention, when the volume fraction of the core-shell particles in the resin composition is defined as Φ, the volume fraction Φ is 0.1 ≦ Φ ≦ 0.6. Preferably there is.

  When the content of the core / shell particles is small, the effect of reducing the temperature dependency (dN / dt) of the refractive index may be reduced. On the other hand, when the content of the core / shell particles is high, the core / shell particles may be reduced. It may be difficult to add the particles to the curable resin, or the viscosity of the mixture may increase, and heat may be generated during kneading, making it difficult to uniformly disperse the core-shell particles. From the above, the volume Φ is preferably 0.1 ≦ Φ ≦ 0.6, more preferably 0.2 ≦ Φ ≦ 0.5, and still more preferably 0.25 ≦ Φ ≦ 0.4.

  The volume fraction Φ of the core-shell particles in the resin composition is calculated by Φ = (total volume of core-shell particles of the resin composition) / (volume of the resin composition).

  An optical element composed of the resin composition according to the present invention can be produced by injecting the mixture obtained by the above method into a mold or the like and curing the mixture with heat or an actinic ray such as an ultraviolet ray or an electron beam. . The molding method is not particularly limited, and when the curable resin is an ultraviolet ray and an electron beam curable resin, the resin composition is filled in a light-transmitting mold having a predetermined shape, or coated on the substrate, and then the ultraviolet ray and the electron beam curable resin are applied. What is necessary is just to cure by irradiating 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.

(Optical element using resin composition)
The optical resin lens according to the present invention can be obtained by the above-described manufacturing method, and specific examples of application to optical components are as follows.

  For example, as an optical lens or an optical prism, an imaging lens of a camera; a lens such as a microscope, an endoscope, or a telescope lens; an all-light transmission lens such as a spectacle lens; , 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;

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

  As an example of the use of the optical resin lens according to the present invention, an example used as an objective lens used in a pickup device for an optical disk will be described with reference to FIG.

  In this embodiment, the target is a “high density optical disk” using a so-called blue-violet laser light source having a used wavelength of 405 nm. This optical disk has a protective substrate thickness of 0.1 mm and a storage capacity of about 30 GB.

  FIG. 1 is a schematic view showing an example of a pickup device for an optical disk to which the optical element (optical resin lens) of the present invention is applied as an objective lens.

  In the optical pickup device 1, the laser diode (LD) 2 is a light source, and a blue-violet laser having a wavelength λ of 405 nm is used, but a laser having a wavelength in the range of 390 nm to 420 nm can be appropriately employed.

  The beam splitter (BS) 3 transmits the light source incident from the LD 2 in the direction of the objective optical element (OBL) 4, but with respect to the reflected light (returned light) from the optical disk (optical information recording medium) 5, the sensor lens (SL). 6 to collect light on the light receiving sensor (PD) 7.

  The light beam emitted from the LD 2 is incident on the collimator (COL) 8, collimated into infinite parallel light, and then incident on the objective lens OBL 4 via the beam splitter (BS) 3. Then, a condensing spot is formed on the information recording surface 5 b via the protective substrate 5 a of the optical disc (optical information recording medium) 5. Then, after reflecting on the information recording surface 5b, the direction of polarization is changed by the quarter wave plate (Q) 9 along the same path, the path is bent by the BS 3, and the sensor (SL) 6 is passed through the sensor ( Condensed on PD) 7. This sensor photoelectrically converts it into an electrical signal.

  The objective optical element OBL4 is a single lens optical resin lens that is injection-molded with resin. An aperture (AP) 10 is provided on the incident surface side to determine the beam diameter. Here, the incident light beam is reduced to a diameter of 3 mm. The actuator (AC) 11 performs focusing and tracking.

  The numerical aperture required for the objective optical element OBL4 varies depending on the thickness of the protective substrate of the optical information recording medium and the size of the pits. Here, the numerical aperture of the high-density optical disk (optical information recording medium) 5 is 0.85.

Example 1
[Oxide fine particle dispersion process]
First, 500 g of pure water and 4.8 g of ammonia water (28% Kanto Kagaku) are added to 23 g of TM-300 (Daimei Chemicals γ-alumina, primary particle diameter 7 nm) and stirred. This solution is dispersed for 4 hours at a peripheral speed of 6.8 m / sec using an Ultra Apex mill (manufactured by Kotobuki Industries Co., Ltd.). At this time, 11.5 g of tetraethoxysilane (LS-2430, manufactured by Shin-Etsu Chemical Co., Ltd.) is dropped into the solution over 2 hours. When the volume average particle diameter of alumina in the dispersion obtained in the above dispersion step was measured using Zeta Sizer 1000HSa (manufactured by Malvern), the volume average particle diameter of the alumina was 24 nm.
[Silica layer forming step]
Dilution is performed by adding 2280 g of ethanol, 1050 g of pure water, and 20 g of ammonia water (28% Kanto Chemical) to 327 g of the alumina fine particle dispersion. 38 g of tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical Co., Ltd.) is added dropwise to the dispersion over 8 hours.

  When the dispersed particle diameter of the silica-coated inorganic oxide fine particle dispersion was measured in ethanol using Zeta Sizer 1000HSa (manufactured by Sysmex Corporation), the volume average particle diameter was 40 nm. The volume average particle diameter of the particles being dropped was 40 nm or less.

  Using an ultrafilter (Vivaflow Co., Ltd.), this dispersion was concentrated once for 5 minutes, added with pure water, and returned to the original liquid volume four times. Concentration to tenths yielded 400 ml of dispersion. 1200 ml of t-butanol was added to this dispersion, and freeze-dried using a freeze dryer FDU-2200 (Tokyo Rika Kikai Co., Ltd.) to obtain 25 g of white particles.

  To 25 g of the particles, 500 ml of pyridine was added, and 100 g of trimethylsilyl chloride (Shin-Etsu Chemical LS-260) was added and stirred for 1 hour. The particles were centrifuged, 100 ml of ethanol was added, and stirring and centrifugation were repeated 4 times for washing. The obtained particles were dried at 150 ° C. for 2 hours to obtain particles 1.

(Example 2)
[Oxide fine particle dispersion process]
First, 500 g of pure water and 5.2 g of ammonia water (28% Kanto Chemical) are added to 46 g of Al—C (Nippon Aerosil, α-alumina, primary particle diameter 13 nm) and stirred. This solution is dispersed for 4 hours at a peripheral speed of 6.8 m / sec using an Ultra Apex mill (manufactured by Kotobuki Industries Co., Ltd.). At this time, 23 g of tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical Co., Ltd.) is dropped into the solution over 2 hours. When the volume average particle diameter (dispersion particle diameter) of alumina in the dispersion obtained in the dispersion step was measured using a Zetasizer 1000HSa (manufactured by Sysmex Corporation), the volume average particle diameter of the alumina was 63 nm.
[Silica layer forming step]
Dilution is performed by adding 1150 g of ethanol, 500 g of pure water and 5 g of ammonia water (28% Kanto Chemical) to 165 g of the alumina fine particle dispersion. To this dispersion, 38 g of tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical Co., Ltd.) is added dropwise over 4 hours.

  When the dispersed particle diameter of the silica-coated inorganic oxide fine particle dispersion was measured in ethanol using Zeta Sizer 1000HSa (manufactured by Malvern), the volume average particle diameter was 82 nm. The volume average particle diameter of the particles being dropped was 82 nm or less.

  Using an ultrafilter (Vivaflow Co., Ltd.), this dispersion was concentrated once for 5 minutes, added with pure water, and returned to the original liquid volume four times. Concentration to tenths yielded 200 ml of dispersion. 600 ml of t-butanol was added to this dispersion, and freeze-dried using a freeze dryer FDU-2200 (Tokyo Rika Kikai Co., Ltd.) to obtain 12 g of white particles.

  To 12 g of the particles, 1000 ml of pyridine was added, and 48 g of trimethylsilyl chloride (Shin-Etsu Chemical LS-260) was added and stirred for 1 hour. The particles were centrifuged, 100 ml of ethanol was added, and stirring and centrifugation were repeated 4 times for washing. The obtained particles were dried at 150 ° C. for 2 hours to obtain particles 2.

(Example 3)
In the same manner as in Example 1, the amount of tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was changed to 46 g and the dropping time was changed to 12 hours in the silica layer forming step. The volume average particle diameter was 50 nm at the end of the silica layer forming step, and the volume average particle diameter was 50 nm or less during the dropwise addition of tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical Co., Ltd.). In this way, particles 3 were obtained.

Example 4
In the same manner as in Example 2, the amount of tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was changed to 46 g and the dropping time was changed to 12 hours in the silica layer forming step. The volume average particle diameter was 90 nm at the end of the silica layer forming step, and the volume average particle diameter was 90 nm or less during the dropwise addition of tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical Co., Ltd.). In this way, particles 4 were obtained.

(Comparative Example 1)
[Oxide fine particle dispersion process]
First, 500 g of pure water and 4.8 g of ammonia water (28% Kanto Kagaku) are added to 23 g of TM-300 (Daimei Chemicals γ-alumina, primary particle diameter 7 nm) and stirred. This solution is dispersed for 4 hours at a peripheral speed of 6.8 m / sec using an Ultra Apex mill (manufactured by Kotobuki Industries Co., Ltd.). At this time, tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical Co., Ltd.) g is dropped into the solution over 2 hours. When the volume average particle diameter (dispersion particle diameter) of alumina in the dispersion obtained in the above dispersion step was measured using Zeta Sizer 1000HSa (manufactured by Sysmex Corporation), the volume average particle diameter of the alumina was 24 nm.

[Silica layer forming step]
Dilution is performed by adding 2280 g of ethanol, 1050 g of pure water, and 20 g of ammonia water (28% Kanto Chemical) to 327 g of the alumina fine particle dispersion. To this dispersion, 38 g of tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical) is dropped at a time.

  Using a Zetasizer 1000HSa (Malvern), the volume average particle size of the core-shell particle dispersion was measured in ethanol. The particles settled immediately after the dripping started, and the dispersed particle size can be measured. There wasn't. The precipitated particles were filtered and washed with ethanol, followed by drying at 100 ° C. for 1 hour. This gave 25 g of white particles.

  To 25 g of the particles, 500 ml of pyridine was added, and 100 g of trimethylsilyl chloride (Shin-Etsu Chemical LS-260) was added and stirred for 1 hour. The particles were centrifuged, 100 ml of ethanol was added, and stirring and centrifugation were repeated 4 times for washing. The obtained particles were dried at 150 ° C. for 2 hours to obtain particles 5.

(Comparative Example 2)
[Oxide fine particle dispersion process]
First, 500 g of pure water and 4.8 g of ammonia water (28% Kanto Kagaku) are added to 23 g of TM-300 (Daimei Chemicals γ-alumina, primary particle diameter 7 nm) and stirred. This solution is dispersed for 4 hours at a peripheral speed of 6.8 m / sec using an ultra apex mill (manufactured by Kotobuki Industries Co., Ltd.). At this time, tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical Co., Ltd.) g is dropped into the solution over 2 hours. When the volume average particle diameter (dispersion particle diameter) of alumina in the dispersion obtained in the dispersion step was measured using Zeta Sizer 1000HSa (manufactured by Sysmex Corporation), the volume average particle diameter of the alumina was 24 nm.

[Silica layer forming step]
Dilution is performed by adding 2280 g of ethanol, 1050 g of pure water, and 20 g of ammonia water (28% Kanto Chemical) to 327 g of the alumina fine particle dispersion. To this dispersion, 38 g of tetraethoxysilane (LS-2430 manufactured by Shin-Etsu Chemical Co., Ltd.) is added dropwise over 2 hours.

  When the volume average particle size of the core-shell particle dispersion was measured in ethanol using Zeta Sizer 1000HSa (Malvern), the volume average particle size was 134 nm. Using an ultrafilter (Vivaflow Co., Ltd.), this dispersion was concentrated once for 5 minutes, added with pure water, and returned to the original liquid volume four times. Concentration to tenths yielded 200 ml of dispersion. 600 ml of t-butanol was added to this dispersion, and freeze-dried using a freeze dryer FDU-2200 (Tokyo Rika Kikai Co., Ltd.) to obtain 25 g of white particles.

  To 25 g of the particles, 500 ml of pyridine was added, and 100 g of trimethylsilyl chloride (Shin-Etsu Chemical LS-260) was added and stirred for 1 hour. The particles were centrifuged, 100 ml of ethanol was added, and stirring and centrifugation were repeated 4 times for washing. The obtained particles were dried at 150 ° C. for 2 hours to obtain particles 6.

(Comparative Example 3)
Similar to Comparative Example 1, the amount of tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was changed to 46 g in the silica layer forming step. In this way, particles 7 were obtained.

(Comparative Example 4)
59 g of aluminum isopropanol are added in 2000 g of t-butanol. Further, 10 ml of ammonium ethanol solution (2 mol / l Kanto Chemical) is added. By adding 5 g of pure water over 30 minutes, an alumina dispersion was obtained. The volume average particle size was 40 nm with a Zetasizer 1000 Hsa (manufactured by Sysmex Corporation).
[Silica layer forming step]
Here, 30 g of tetraethoxysilane (LS-2430, manufactured by Shin-Etsu Chemical Co., Ltd.) was dropped over 5 hours, and at the same time, 8 g of pure water and 4 g of ammonia water (28% Kanto Chemical) were dropped in parallel over 5 hours. An alumina dispersion was obtained. Zeta Sizer 1000Hsa (manufactured by Sysmex Corporation) had a volume average particle size of 60 nm. The volume average particle diameter of the particles being dropped was 60 nm or less. This solution was lyophilized to obtain 25 g of white particles.

  To 25 g of the above particles, 500 ml of pyridine was added, and 100 g of trimethylsilyl chloride (Shin-Etsu Chemical LS-260) was added and stirred for 1 hour. The particles were centrifuged, 100 ml of ethanol was added, and stirring and centrifugation were repeated 4 times for washing. The obtained particles were dried at 150 ° C. for 2 hours to obtain particles 8.

[Production of optical elements]
<Optical element>
Add 1.5 g of isobornyl methacrylate to 1.5 g of tricyclodecane dimethanol dimethanol dimethacrylate, 0.03 g of Parroyl L (Nippon Yushi Co., Ltd.), stabilizer (tetrakis (1,2,2,6,6- 0.03 g of pentamethylpiperidyl) butanetetracarboxylate), 0.06 g of stabilizer (2,2′-methylenebis (4,6-di-t-butylphenyl) -2-ethylhexyl phosphite), surfactant (penta Add 0.06 g of (erythritol distearate) and stir. Using a Laboplast mill (Laboplast Mill KF-6V, manufactured by Toyo Seiki Seisakusho Co., Ltd.) as a kneading device, the above-mentioned resin 1 and particles 1, 2, 5, 6, and 8 were mixed for 10 minutes at 10 rpm under nitrogen. A uniform resin composition was obtained by kneading. Each of the obtained resin compositions was filled in a mold having dimensions of 30 mm × 30 mm × 3 mm, and then heated and pressed at 160 ° C. for 20 minutes to obtain a molded plate. The samples are 1, 2, 5, 6, and 7, respectively.

<Optical element 2>
Add 2.7 g of tricyclodecane dimethanol dimethanol dimethacrylate to 0.3 g of isobornyl methacrylate, 0.03 g of Parroyl L (Nippon Yushi Co., Ltd.), stabilizer (tetrakis (1,2,2,6,6- 0.03 g of pentamethylpiperidyl) butanetetracarboxylate), 0.06 g of stabilizer (2,2′-methylenebis (4,6-di-t-butylphenyl) -2-ethylhexyl phosphite), surfactant (penta Add 0.06 g of (erythritol distearate) and stir. Using a lab plast mill (labor plast mill KF-6V manufactured by Toyo Seiki Seisakusho Co., Ltd.) as a kneading device, the above thermosetting resin and particles 2, 3, 4, and 7 are kneaded for 10 minutes at 10 rpm under nitrogen. A uniform thermosetting resin composition was obtained by kneading. Each of the obtained resin compositions was filled in a mold having dimensions of 30 mm × 30 mm × 3 mm, and then heated and pressed at 160 ° C. for 20 minutes to obtain a molded plate. The samples are 9, 9, 4, and 7, respectively.

[Evaluation of inorganic fine particles and sample]
<Evaluation method of refractive index of particles>
0.04 g of particles 1 to 8 was added to 4 g of TOPAS-TM (manufactured by Polymerex) and melt kneaded for 5 minutes using a lab plast mill (KF-6V). Before completion, vacuum degassing was performed at 20 Torr for 2 minutes, and the mixture was heated and melted to form a plate having a thickness of 3 mm.

  A section of the obtained plate was prepared, STEM observation-EDX mapping was performed for each sample, and for each of the 200 randomly selected dispersed particles, each element derived from each oxide (silicon, The ratio of metal elements such as Al, Ti, and Mg was calculated. From the ratio, the refractive index of each dispersed particle was calculated, and the average value was defined as the core-shell particle refractive index Np of each particle.

<Evaluation method of refractive index and dn / dT change rate of resin and sample>
Resins 1 and 2 to which particles 1 to 8 are not added are cured, processed and polished, and the temperature of the resin is changed from 23 ° C. to 60 ° C. using an automatic refractometer (KPR-200 manufactured by Kalnew Optical Industry). In addition, the refractive index of light having a wavelength of 588 nm at each temperature was measured, and the temperature change rate of the refractive index accompanying the temperature variation was calculated. The refractive index in light having a wavelength of 588 nm at 23 ° C. was defined as “refractive index Nm” of the resin. The refractive index Nm of this resin is shown in the drawing.

  In the same manner as above, each sample 1-9 was heated and melted, then formed into a plate shape with a thickness of 3 mm, and the temperature of each sample 1-9 was changed from 23 ° C. to 60 ° C. at each temperature. While measuring the refractive index in the light of wavelength 588nm, the temperature change rate of the refractive index accompanying the temperature fluctuation was computed for every sample 1-6. Based on these calculation results, the change rate of dn / dT of each sample was calculated by the following formula.

dn / dT change rate = (dn / dT of resin−dn / dT of each sample) / (dn / dT of resin) × 100
<Evaluation method for refractive index dispersion of dispersed particles of inorganic fine particles>
0.04 g of particles 1 to 8 was added to 4 g of TOPAS-TM (manufactured by Polymerex) and melt kneaded for 5 minutes using a lab plast mill (KF-6V). Before completion, vacuum degassing was performed at 20 Torr for 2 minutes, and the mixture was heated and melted to form a plate having a thickness of 3 mm.

  A section of the obtained plate was prepared, STEM observation-EDX mapping was performed for each sample, and each sample was composed of 200 randomly selected dispersed particles. The ratio of metal elements such as Al, Ti, and Mg was calculated. From the ratio, the refractive index of each dispersed particle was calculated, and the standard deviation σ (refractive index distribution Nd of core / shell particles) of each sample was calculated by the following formula (1).

<Measurement of light transmittance of sample>
About the samples 1-9, the transmittance | permeability of the thickness direction in the light of wavelength 405nm and 588nm was measured with the spectrophotometer (Shimadzu Corporation UV-3150).

  The various measurement / evaluation results are summarized in Table 1.

  As is apparent from the results shown in Table 1, the sample according to the present invention is excellent in performance such as the refractive index, the dn / dT change rate, the dispersion of the refractive index of the dispersed particles of inorganic fine particles, and the light transmittance. I understand.

Schematic diagram showing an example of an optical disk pickup device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical pick-up apparatus 2 Laser diode 3 Beam splitter 4 Objective optical element (It is also called "objective lens.")
DESCRIPTION OF SYMBOLS 5 Optical disk 5a Protective board 5b Information recording surface 6 Sensor lens 7 Sensor 8 Collimator 9 1/4 wavelength plate 10 Aperture 11 Actuator

Claims (5)

A method for producing a resin composition containing inorganic oxide particles having a core / shell structure in a resin, comprising at least a core particle dispersing step and a silica layer forming step, wherein in the silica layer forming step, the volume of the core particles While maintaining the particle dispersion diameter at 1 to 100 nm, the surface of the core particles in the liquid is coated with a silica layer to form inorganic oxide particles having a core / shell structure (hereinafter referred to as “core / shell particles”). The manufacturing method of the resin composition characterized by mixing the said inorganic oxide particle and resin which satisfy | fills the following conditional expression.
Conditional expression: | Np−Nm | <0.005
In the formula, Np: refractive index of core / shell particles, Nm: refractive index of resin Before coating the surface of the core particles with a silica layer, 100% by mass or less of a silica precursor is added to and dispersed in the core particles, so that the volume particle dispersion diameter of the core particles is 1 to 100 nm. The manufacturing method of the resin composition of Claim 1 characterized by the above-mentioned. A resin composition produced by the method for producing a resin composition according to claim 1. The resin composition according to claim 3, wherein the resin composition satisfies the following conditional expression.
Conditional expression: Nd <0.01
Nd: Core-shell particle refractive index distribution An optical element produced using the resin composition according to claim 3.

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