JP2007270097A - High refractive index resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating-type inorganic oxide ultrafine particle having a high refractive index, and excellent transparency, dispersibility, light resistance, weather resistance, or the like; sol with the ultrafine particle dispersed in water or an organic solvent; a high refractive index transparent resin composition and an optical material each with the ultrafine particle dispersed therein in high concentration; and to further provide a material for optical components including an optical lens (such as a spectacle lens, a Fresnel lens, a pickup lens for information recording equipment such as a CD and a DVD, and a lens for photographing equipment such as a digital camera), an optical prism, an optical waveguide, an optical fiber, a thin film molded product, an optical adhesive, an optical semiconductor sealing material, diffraction grating, a light guide plate, a liquid crystal substrate, a light reflection plate, and an antireflection material. <P>SOLUTION: The resin composition has a rutile-type titanium dioxide ultrafine particle having a refractive index of 1.5 to 2.8, as a nucleus, and contains a coating-type inorganic oxide ultrafine particle with a coating layer made of a silicon oxide formed thereon by using a specific technique. The optical components containing the resin composition are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a novel resin composition having excellent transparency and a high refractive index and used as an optical member. Specifically, high-refractive-index inorganic oxide ultrafine particles excellent in transparency, dispersibility, light resistance, weather resistance, etc., a sol solution in which the ultrafine particles are dispersed in water or an organic solvent, and the ultrafine particles are highly concentrated. The present invention relates to a transparent resin composition having a high refractive index which is dispersed in an organic substance such as a transparent resin at a concentration.

  Inorganic glass is excellent in various physical properties such as excellent transparency, and is used in a wide field as an optical member. However, it is disadvantageous in that it is heavy and easily damaged, and the workability and productivity are poor. Thus, transparent optical resins have been actively developed as a material to replace inorganic glass. Non-represented by acrylic resin, styrene resin, polycarbonate resin, polyester resin, olefin resin, alicyclic acrylic resin, alicyclic olefin resin, polyurethane resin, polyether resin, polyamide resin, polyimide resin A curable resin such as a crystalline thermoplastic resin, or an epoxy resin, an unsaturated polyester resin, or a silicone resin has good transparency in the visible region wavelength, and has a moldability, mass productivity, or It is a general-purpose transparent resin material having excellent characteristics such as flexibility, toughness and impact resistance. By providing such a transparent resin material with a high refractive index, a thin and light optical lens (glass lens, Fresnel lens, pickup lens in information recording equipment such as CD and DVD, lens for photographing equipment such as a digital camera, etc.) , Optical prisms, optical waveguides, optical fibers, thin film moldings, optical adhesives, optical semiconductor sealing materials, diffraction gratings, light guide plates, liquid crystal substrates, light reflectors, antireflective materials, etc. Expansion to is expected.

For example, in the field of spectacle lenses, in order to meet the needs of fashionableness, it is necessary to reduce the center thickness, edge thickness, and curvature of the lens, and to be thin overall. From this point, higher refractive index is required. In recent years, research into increasing the refractive index by using a monomer containing an element having a large atomic number such as sulfur or a halogen element has been actively conducted. For example, a resin (n _d = 1.60 to 1.67) obtained by thermal polymerization of a thiol compound and an isocyanate compound to form a thiourethane bond, a resin obtained by polymerizing and curing an episulfide or epithiosulfide compound (n _d = About 1.7) (Patent Document 1). Similarly, non-represented by acrylic resins, styrene resins, polycarbonate resins, polyester resins, olefin resins, alicyclic acrylic resins, alicyclic olefin resins, polyurethane resins, polyether resins, polyamide resins, and polyimide resins. There is a strong demand for higher refractive index of general-purpose transparent resin such as crystalline thermoplastic resin or curable resin such as epoxy resin, unsaturated polyester resin, silicone resin, especially high refractive index resin having a refractive index of 1.7 or more. Yes. However, since the refractive index of the organic resin is determined by the element used and the molecular structure, it can be increased by the introduction of such a halogen element or sulfur element, but the range is usually about 1.4 to 1.7. .

  Also, for example, for a polymer optical fiber using an acrylic resin such as polymethyl methacrylate (PMMA), the refractive index of the core part (center part in the optical fiber cross section) is higher than that of the cladding part (same outer peripheral part). As the rate difference is larger, the numerical aperture corresponding to the maximum angle at which light can propagate can be increased.

  For example, in a light emitting diode, a light emitting element portion is sealed with an epoxy resin or the like. In general, the refractive index of a semiconductor constituting the semiconductor element portion is very high. If the refractive index of a substance in contact with the semiconductor element portion is low, the critical angle is small and total reflection tends to occur. Therefore, the angle at which the total reflection occurs can be increased by sandwiching the light emitting element with a material having a higher refractive index, and the light beam extraction efficiency is improved accordingly.

  Furthermore, it is also desired to develop a material having a plurality of materials having different refractive indexes, such as an optical fiber, an optical waveguide, and some lenses, or having a distribution in the refractive index. In order to cope with these materials, it is indispensable to arbitrarily adjust the refractive index.

  Thus, resins used for optical members, such as acrylic resins, styrene resins, polycarbonate resins, polyester resins, olefin resins, alicyclic acrylic resins, alicyclic olefin resins, polyurethane resins, polyether resins, polyamide resins In addition, a thermoplastic resin typified by a polyimide resin or the like, or a curable resin such as an epoxy resin, an unsaturated polyester resin, or a silicone resin, or an element having a large atomic number such as sulfur or a halogen element as described in Patent Document 1 above. It is strongly desired to increase the refractive index of a resin obtained by polymerizing the contained monomer.

  In recent years, for the purpose of increasing the refractive index of resins, transparent inorganic oxide fine particles having a high refractive index having a crystal structure such as Zr, Sn, Sb, Mo, In, Zn, Ti, or composite oxides thereof have been dispersed. A technique for forming a colorless and transparent high refractive index resin by introducing it into the resin while maintaining the state has been proposed. Since high dispersibility and transparency are required for use in such applications, the inorganic oxide is preferably ultrafine particles.

  However, in the above technique, it has not been sufficient to design a resin having a high refractive index while using a matrix amount that can maintain strength and the like. This is because if the content of fine particles is too large to increase the refractive index, the resin becomes brittle.

  Therefore, a method using titanium oxide fine particles has been proposed. Since titanium oxide has a particularly high refractive index and high transparency, the resin can have a high refractive index in a smaller amount than other fine particles. Titanium oxide includes a rutile type and an anatase type as typical crystal types. So far, materials mainly composed of anatase-type titanium oxide ultrafine particles having a refractive index no = 2.56 and ne = 2.49 have been mainly used as high refractive index metal oxide ultrafine particle sol solutions. Yes. On the other hand, the refractive index of rutile-type titanium oxide has a refractive index no = 2.61, ne = 2.9 (no: refractive index for ordinary light, ne: refractive index for extraordinary light) (Chemical Society of Japan, Experimental Science) It is known that the optical properties such as high refractive index and ultraviolet absorption are superior to those of anatase type, and attempts to synthesize the rutile titanium oxide ultrafine particles and sol liquid are positive. It was done. However, the rutile type titanium oxide ultrafine particles and sol liquid that can be used industrially have not been obtained yet. For example, as reported in Jpn. J. Appl. Phys., 37, 4603 (1998), an aggregate having an aggregate particle diameter of 200 to 400 nm in which long-fiber rutile titanium oxide is gathered is produced. In this situation, it was impossible to use industrially.

  On the other hand, a resin composed of an organic matrix and titanium oxide fine particles has a drawback that its light resistance is lowered. That is, due to the photocatalytic action of titanium oxide, organic matter decomposition due to electron-holes generated by light absorption occurs, and transparency, light resistance, weather resistance, heat resistance, ultraviolet shielding properties, and the like are serious problems.

  At present, for the purpose of improving the light resistance of a resin composition containing such anatase-type titanium oxide ultrafine particles, for example, ultrafine particles combining anatase-type titanium oxide and an inorganic oxide as described in Patent Document 2, or anatase Ultrafine particles obtained by coating type titanium oxide with an inorganic oxide and sol liquids thereof are applied.

  All of these are aimed at inactivating the anatase-type titanium oxide ultrafine particles by coating with an inorganic oxide. Thus, light resistance is improved by coat | covering a titanium oxide ultrafine particle with an inorganic oxide. However, it has not been able to satisfy long-term light stability such as discoloration and fading due to deterioration of surrounding organic substances, and a decrease in hardness. Furthermore, there was a problem that coloring was observed depending on the metal used. In addition, since the titanium oxide used is anatase type, the refractive index is about 2.5, and when coated with an oxide to improve light resistance, the refractive index is greatly reduced, The refractive index is lower than the original anatase-type titanium oxide, and the effect of improving the refractive index of the resin composition is low. Further, even if the amount of the metal oxide to be coated is reduced and the refractive index is increased, the light resistance is insufficient, and the transparency, heat resistance, ultraviolet shielding property, etc. of the resin composition are problematic.

  On the other hand, the rutile type titanium oxide having a higher refractive index than the conventional anatase type titanium oxide, as described above, has no ultrafine particles and sol liquid that can be used.

Similarly, high-refractive-index ultrafine particles excellent in transparency, dispersibility, light resistance, weather resistance, etc., and thin and light optical lenses (glass lenses, Fresnel lenses, CDs, DVDs, and other pickup lenses in information recording equipment) , Lenses for photographic equipment such as digital cameras, etc.), optical prisms, optical waveguides, optical fibers, thin film moldings, optical adhesives, optical semiconductor sealing materials, diffraction gratings, light guide plates, liquid crystal substrates, light reflectors, reflections Not only high-refractive optical member materials such as prevention materials, but also plastic deterioration prevention additives, cosmetic additives, automotive window glass, plasma displays, liquid crystal displays, EL displays, optical filters and other optical members, metal materials, ceramic materials , Glass materials, plastic materials, photocatalysts, etc. are also required.
Japanese Patent Laid-Open No. 9-110956 JP 2001-123115 A

  The object of the present invention has been achieved in view of the above circumstances, and is a coated inorganic oxide ultrafine particle having a high refractive index and excellent transparency, dispersibility, light resistance, weather resistance, etc., and the ultrafine particle is water or The object is to provide a sol solution dispersed in an organic solvent, a high refractive index resin composition and an optical member obtained by dispersing the ultrafine particles in a high concentration. In particular, thin and light optical lenses (glass lenses, Fresnel lenses, pickup lenses in information recording equipment such as CDs and DVDs, lenses for photographing equipment such as digital cameras, etc.), optical prisms, optical waveguides, optical fibers, thin film moldings, optical It is to provide materials for optical members such as adhesives for optical semiconductors, sealing materials for optical semiconductors, diffraction gratings, light guide plates, liquid crystal substrates, light reflection plates, and antireflection materials.

  As a result of intensive studies to solve the above problems, the present inventors have found that tin compounds used as a sintering agent prevent long fiber formation and aggregation, and tin-modified rutile titanium oxide ultrafine particles. It was found that a sol solution excellent in transparency, dispersibility, etc. was obtained, and this was made into a core ultrafine particle, and by providing a coating layer containing silicon oxide by a specific method, transparency, dispersibility, light resistance The present inventors have found that coated inorganic oxide ultrafine particles having a high refractive index and an average particle diameter of 1 to 100 nm excellent in weather resistance and the like, and a sol liquid excellent in dispersibility can be obtained. And, by dispersing the ultrafine particles in a high concentration in the resin, high refractive index, transparency, light resistance, weather resistance, heat resistance, molding processing that could not be obtained when using conventional anatase type titanium oxide Resin compositions with excellent properties, especially thin and light optical lenses (glass lenses, Fresnel lenses, pickup lenses in information recording equipment such as CDs and DVDs, lenses for photographing equipment such as digital cameras), optical prisms, optical waveguides , Found that optical members such as optical fibers, thin film moldings, optical adhesives, sealing materials for optical semiconductors, diffraction gratings, light guide plates, liquid crystal substrates, light reflectors, and antireflection materials can be obtained and completed the present invention It came to do.

That is,
[1] An inorganic oxide ultrafine particle containing titanium oxide having a rutile crystal structure with a refractive index of 1.5 to 2.8 is used as a nucleus (A), and is composed of a coating layer (B) containing silicon oxide. A resin composition comprising coated inorganic oxide ultrafine particles having an inorganic oxide coating layer.
[2] Rutile-type titanium oxide ultrafine particles in inorganic oxide ultrafine particles containing titanium oxide having a rutile-type crystal structure of the nucleus (A),
In the presence of a tin compound having a molar ratio of tin to titanium (Sn / Ti) of 0.001 to 2, a titanium compound aqueous solution having a Ti concentration of 0.07 to 5 mol / l is reacted in a pH range of −1 to 3. Obtained tin-modified rutile titanium oxide ultrafine particles having a Sn / Ti composition molar ratio of 0.001 to 0.5,
The coating layer containing silicon oxide (B) is of a two-layer coating type, the inner layer has a coating layer obtained by the step (1), and the outer layer is obtained by the step (2), it is a coating-type inorganic oxide ultrafine particles, wherein the weight ratio of the oxide coating layer is 0.001 to 20 in terms of SiO ₂ [1] resin composition.
(1) Step of reacting silicon oxide having a weight ratio with respect to the nucleus (A) of 0.001 to 10 in terms of SiO ₂ with the nucleus (A) under the condition of pH <7 (2) with respect to the nucleus (A) The step of reacting the silicon oxide having a weight ratio of 0.001 to 10 in terms of SiO ₂ with the coated ultrafine particles obtained in (1) under the condition of pH ≧ 7 [3] The coated inorganic oxide The resin composition according to [1] or [2], wherein the ultrafine particles have a minor axis and a major axis of 2 to 20 nm.
[4] The resin composition according to any one of [1] to [3], wherein an average aggregate particle diameter of the aggregate composed of the coated inorganic oxide ultrafine particles is 10 to 100 nm.
[5] The resin composition according to any one of [1] to [4], wherein a sol obtained by dispersing the coated inorganic oxide ultrafine particles in water or an organic solvent is used.
[6] The resin composition according to any one of [1] to [5], wherein the surface of the coated inorganic oxide ultrafine particles is treated with an organosilicon compound or an amine.
[7] The resin composition according to any one of [1] to [6], which has a refractive index of 1.5 to 2.8.
[8] An optical member comprising the resin composition according to any one of [1] to [7].
[9] The optical member according to [8], which is used for an optical lens, an optical prism, an optical waveguide, an optical fiber, a thin film molding, an optical adhesive, or an optical semiconductor sealing material.
It is about.

  The tin-modified rutile type titanium oxide ultrafine particles of the present invention can be provided as ultrafine particles and sol liquid having a high refractive index that cannot be obtained by the conventional production method and that cannot be obtained by the anatase type. Using this tin-modified rutile-type titanium oxide ultrafine particle as a nuclear ultrafine particle, and providing a coating layer containing silicon oxide by a specific method, transparency, dispersibility, light resistance, weather resistance that could not be obtained by conventional coating methods It is possible to provide a coated inorganic oxide ultrafine particle having a high refractive index and excellent in properties and the like. High-refractive index resin composition excellent in transparency, light resistance, weather resistance, heat resistance, molding processability, etc. when these obtained ultrafine particles and sol solution are applied to an optical member, and optical using the same It became possible to provide components.

  Hereinafter, the present invention will be described in more detail.

  The resin composition according to the present invention is a coating comprising (1) ultrafine titanium oxide particles having a rutile crystal structure having a refractive index of 1.5 to 2.8 as core particles, and the core particles and silicon oxide. Coated inorganic oxide ultrafine particles composed of layers or a sol thereof, and a resin composition containing the ultrafine particles.

That is,
Inorganic oxidation composed of a coating layer (B) containing silicon oxide with an inorganic oxide ultrafine particle containing titanium oxide having a rutile crystal structure having a refractive index of 1.5 to 2.8 as a nucleus (A) A resin composition comprising coated inorganic oxide ultrafine particles having a material coating layer,
The rutile type titanium oxide ultrafine particles in the inorganic oxide ultrafine particles containing titanium oxide having the rutile type crystal structure of the nucleus (A),
In the presence of a tin compound having a molar ratio of tin to titanium (Sn / Ti) of 0.001 to 2, a titanium compound aqueous solution having a Ti concentration of 0.07 to 5 mol / l is reacted in a pH range of −1 to 3. Obtained tin-modified rutile titanium oxide ultrafine particles having a Sn / Ti composition molar ratio of 0.001 to 0.5,
The coating layer containing silicon oxide (B) is of a two-layer coating type, the inner layer has a coating layer obtained by the step (1), and the outer layer is obtained by the step (2), The resin composition, which is a coated inorganic oxide ultrafine particle, wherein the weight ratio of the oxide coating layer is 0.001 to 20 in terms of SiO ₂ .
(1) Step of reacting silicon oxide having a weight ratio with respect to the nucleus (A) of 0.001 to 10 in terms of SiO ₂ with the nucleus (A) under the condition of pH <7 (2) with respect to the nucleus (A) The step of reacting the silicon oxide having a weight ratio of 0.001 to 10 in terms of SiO ₂ with the coated ultrafine particles obtained in (1) under the condition of pH ≧ 7

  As described above, since the rutile type has a higher refractive index than the anatase type, it is possible to achieve a higher refractive index by using ultrafine particles of rutile type titanium oxide. Furthermore, in order not to impair the transparency of the resin, the rutile titanium oxide needs to be ultrafine particles.

  In the present invention, the inorganic oxide ultrafine particles containing titanium oxide having a rutile-type crystal structure, as long as it contains rutile-type titanium oxide formed into ultrafine particles as described above, the rutile-type crystal structure Even if it is a complex with a titanium oxide having a rutile crystal structure, it may be a shape that covers a titanium oxide having a rutile type crystal structure, and is not particularly limited. The ratio of rutile type titanium oxide is 5 to 100% (weight ratio), preferably 50 to 100%, and more preferably 70 to 100%.

  In addition, components other than ultrafine particles of rutile-type titanium oxide may be used as long as they do not impair the dispersion stability of the ultrafine particles of the present invention, and may be those that do not impair the transparency of the resin of the present invention. Although there is no particular limitation, an inorganic oxide is preferable. Specific examples include oxides such as Al, Si, V, Fe, Zn, Zr, Nb, Mo, Sn, Sb, and W, and preferably oxidation of Al, Si, Zr, Sn, and Sb. It is a thing.

  In the present invention, a preferable rutile type titanium oxide ultrafine particle is a core fine particle, and the coated inorganic oxide ultrafine particle composed of a coating layer containing the core fine particle and silicon oxide is more specifically, rutile. Type titanium oxide ultrafine particles, in the presence of a tin compound having a molar ratio of tin to titanium (Sn / Ti) of 0.001 to 2, a titanium compound aqueous solution having a Ti concentration of 0.07 to 5 mol / l has a pH of −1 to 1. Tin-modified rutile-type titanium oxide ultrafine particles obtained by reacting in the range of 3, the Sn / Ti composition molar ratio of the ultrafine particles being 0.001 to 0.5, and the short axis and long of the crystal diameter Tin-modified rutile titanium oxide ultrafine particles characterized in that the axis is 2 to 20 nm and the average aggregate particle diameter of the ultrafine particle aggregate crystals is 10 to 100 nm are used as the core fine particles. Is a coating-type inorganic oxide ultrafine particles composed of uncoated layer.

  The crystal diameter referred to here is a so-called primary particle diameter, and is expressed by the lengths in the a and c axis directions as described in Chemical Handbook Revision 3 (Basic Edition Maruzen Co., Ltd.). In this specification, they are called a short axis and a long axis, respectively. Moreover, the average aggregated particle diameter represents a particle diameter obtained by aggregating primary particles.

  First, a method for producing tin-modified rutile titanium oxide ultrafine particles will be described.

  The tin compound used in the present invention is not particularly limited, but specifically, for example, a tin salt compound such as tin chloride, tin nitrate, tin sulfate, stannate, or an oxide, hydroxide, metal Preferred examples include tin compounds selected from tin and the like.

  The titanium compound used in the present invention is not particularly limited. Specifically, for example, titanium chloride oxide, titanium sulfate, titanium nitrate, titanium alkoxide, hydrated titanium oxide (a titanium compound in advance under alkaline conditions). Preferred examples include titanium compounds selected from such as hydrolyzed ones).

  First, a tin compound is added to an aqueous solution, and a titanium compound is added thereto. The tin compound and the titanium compound may be added at the same time, or either one may be first. Moreover, the form of a mixed compound may be sufficient. The reaction medium is preferably water, but may be an organic solvent such as alcohol or a mixed medium of water and an organic solvent.

  The amount of tin compound used in the reaction as a modifier for controlling crystal growth of rutile titanium oxide is such that the molar ratio of tin to titanium (Sn / Ti) is 0.001 to 2, preferably 0.01 to 1. It is desirable. If the tin amount is less than the above range, rutile-type titanium oxide ultrafine particles are produced, but the crystal diameter and aggregated particle diameter are increased, and therefore the dispersibility may be deteriorated. Moreover, the transparency of the resin composition may be reduced. Further, even if the amount is larger than the above range, it is possible to synthesize the titanium oxide ultrafine particles having the rutile type, but the time required for the reaction becomes long. In this case, a large amount of tin compound is contained in the rutile type titanium oxide ultrafine particles. There is a possibility that a product with attached will be obtained. On the other hand, if it is larger than this, the amount of the residual tin compound increases, and the particle refractive index may decrease.

  The Ti concentration in the reaction solution is 0.07 to 5 mol / l, preferably 0.1 to 1 mol / l. When the Ti concentration is lower than the above range, there is a possibility that anatase-type and rutile-type mixed titanium oxide ultrafine particles may be produced even if a tin compound is added in the range of 0.01 to 0.03 as Sn / Ti (molar ratio). is there. Similarly, at a Ti concentration lower than the above range, if a tin compound is added in a range larger than 0.03 as Sn / Ti (molar ratio), there is a possibility that titanium oxide-tin oxide mixed ultrafine particles having rutile tin oxide are generated. is there.

  The pH of the reaction solution is desirably −1 to 3. Adjust with hydrochloric acid or nitric acid as necessary. When the reaction is carried out under a condition where the pH is greater than 3, anatase-type titanium oxide is obtained in the case where no tin compound is added, and in order to avoid this, a tin compound is added to obtain a rutile structure. There is a possibility that foreign substances other than rutile-type titanium oxide are produced.

  Regarding the reaction temperature, the Ti concentration and pH may be in the above ranges, and there is no particular limitation, but preferably −10 to 100 ° C., more preferably 20 to 60 ° C. is recommended. Although the reaction completion time is determined depending on the reaction temperature, it is usually carried out in 0.5 to 10 hours.

  The amount of tin compound contained in the tin-modified rutile-type titanium oxide ultrafine particles produced by the above reaction is preferably Sn / Ti molar ratio = 0.001 to 0.5. If the amount of tin is made smaller than the above range, the particle diameter of the rutile titanium oxide ultrafine particles becomes large and the dispersibility may be deteriorated. Also, if the amount is larger than the above range, crystal growth and aggregation can be controlled more efficiently, and ultrafine particles with a small particle diameter can be obtained, but a rutin-type titanium oxide ultrafine particle with a large amount of tin compound attached can be obtained. As a result, ultrafine particles having a low refractive index may be obtained.

  The minor axis and major axis of the tin-modified rutile-type titanium oxide ultrafine particles obtained by this method have a minor axis and a major axis of 2 to 20 nm, and an average aggregated particle diameter of 10 to 100 nm.

  Although the reaction mechanism (reaction mechanism) by which the tin-modified rutile-type titanium oxide ultrafine particles of the present invention are obtained is not sufficiently clear at present, this is characterized in that the surface is modified with a tin compound. It is presumed that the tin compound used as the raw material, the tin ion dissociated in the solution, or the tin compound generated in the solution by hydrolysis or the like adhered to the titanium oxide surface by coordination, adsorption, chemical bonding, or the like. In addition, it is presumed that the tin compound was originally added as a modifier under the conditions for producing rutile type titanium oxide instead of the anatase type, and this was caused as a result of the inhibition of crystal growth in the major axis direction. This indicates that the amount of the modified tin compound necessary for obtaining tin-modified titanium oxide ultrafine particles having a crystal diameter of 2 to 20 nm is far from the amount of titanium oxide coated without a gap, and the molar ratio to titanium is 0. It can be seen from the small amount of 001-0.5.

  The reaction product obtained as described above may be used as tin-modified rutile-type titanium oxide ultrafine particles or sol liquid as it is, or may be subjected to a desired post-treatment. That is, it can be purified by a known method such as vacuum concentration using an evaporator or ultrafiltration, and concentrated to an appropriate concentration. Centrifugation can yield a white precipitate that can be redispersed in water or other desired organic solvents. The sol liquid in which tin-modified rutile-type titanium oxide ultrafine particles are dispersed in water is substituted with an organic solvent such as alcohols such as methanol and cellosolves such as 2-methoxyethanol, and organic solvent-dispersed tin-modified rutile-type titanium oxide It can also be used as an ultrafine particle sol solution.

  Next, a method for preparing the coating layer (B) containing silicon oxide will be described.

The coating layer (B), that is, the coating layer containing silicon oxide, is a two-layer coating type, in which the inner layer is obtained by the step (1) and the outer layer is obtained by the step (2). The weight ratio of the material coating layer is 0.001 to 20 in terms of SiO ₂ .
(1) Step of reacting silicon oxide having a weight ratio with respect to the nucleus (A) of 0.001 to 10 in terms of SiO ₂ with the nucleus (A) under the condition of pH <7 (2) with respect to the nucleus (A) The step of reacting the silicon oxide having a weight ratio of 0.001 to 10 in terms of SiO ₂ with the coated ultrafine particles obtained in (1) under the condition of pH ≧ 7

  In the present invention, when the tin-modified rutile-type titanium oxide ultrafine particles synthesized above or a sol solution thereof is used for a resin composition or an optical member containing the resin composition, deterioration of surrounding organic substances due to the photocatalytic property of titanium oxide is prevented. Therefore, it is necessary to provide light resistance. For this purpose, a rutile titanium oxide ultrafine particle is provided with a coating layer containing silicon oxide. In addition, a coating means both the form which covered the ultrafine particle surface completely, or the form with which the clearance gap was vacant.

  Examples of the silicon oxide used for the coating include silicates such as colloidal silica, silicate sol, sodium silicate, or potassium silicate. The silicon oxide here may be an amorphous oxide, a crystalline oxide, or a hydrated state. Further, it may be silicic acid, silicic acid oligomer, or a salt thereof, and may be in a state in which they are adsorbed and bound to the surface of the nuclear fine particles.

  As a method for forming the coating layer, first, a sol solution of tin-modified rutile-type titanium oxide ultrafine particles is prepared. It is desirable to dilute or concentrate the sol solution prepared above so that the solid content is 0.01 to 20% by weight, preferably 0.1 to 5% by weight. When the solid content concentration of the dispersion is less than 0.01% by weight, the productivity is low and not industrially effective, and when the solid content concentration of the dispersion exceeds 20% by weight, the resulting ultrafine particles may become aggregates. There is sex.

  A solution in which silicon oxide is dissolved in water and / or an organic solvent is continuously or intermittently added to a reaction liquid containing nuclear fine particles (in this case, tin-modified rutile-type titanium oxide ultrafine particles which are nuclei (A)). Add to react on the surface of the core particle. It is desirable to drop over 0.1 to 100 hours (to the extent that the core fine particle sol solution does not gel). The concentration after the completion of dropping of the silicon oxide in the reaction solution is preferably 0.01 to 5 wt% in terms of silicon oxide. If it is smaller than this, the productivity is low and it is not industrially effective, and if it is larger than this, polymerization may proceed too much and an insoluble substance of silicon oxide may be formed.

[Step (1): A step of reacting a silicon oxide having a weight ratio with respect to the nucleus (A) of 0.001 to 10 in terms of SiO ₂ with the nucleus (A) under the condition of pH <7.
First, the core fine particles, that is, the core (A) and the silicon oxide having a weight ratio with respect to the core (A) of 0.001 to 10 in terms of SiO ₂ are reacted under the condition of pH <7.

Although there is no restriction | limiting in particular as a silicon oxide used here, Colloidal silica and silicate sol are preferable. The amount to be used, the weight ratio of the nucleus (A) is 0.001 to 10 is preferable in terms of SiO ₂ is preferably 0.01 to 0.5. If it is in this range, that is, greater than 10, a sufficient refractive index may not be obtained. If it is less than this range, that is, 0.001, dispersion stability may be lowered.

  The pH of the reaction solution is preferably less than 7, and more preferably 2-4. When the pH is 7 or more, tin-modified rutile titanium oxide ultrafine particles, which are core fine particles, may cause aggregation and gelation. Further, if the pH is too lower than 1, the electric double layer of the nuclear fine particles is shielded by excess positive ions, which may cause aggregation. You may adjust pH by adding an acidic compound or a basic compound as needed. Examples of acidic compounds include hydrochloric acid, sulfuric acid, and nitric acid, and basic compounds include sodium hydroxide and potassium hydroxide.

  In this step, a solution in which silicon oxide is dissolved in water and / or an organic solvent is continuously or intermittently added to the reaction liquid containing the nuclear fine particles to react on the surface of the fine nuclear particles. It is desirable to drop the sol solution so that the core fine particle sol solution does not gel over 0.1 to 100 hours. Longer than this is not economically efficient. If it is shorter than this, the reaction may be insufficient.

  Although reaction temperature does not have a restriction | limiting in particular, 0-200 degreeC is preferable and 30-100 degreeC is more preferable. If it is in this range, that is, higher than 200 ° C., ultrafine particles may be aggregated. If it is less than this range, that is, 0 ° C., the reaction may not proceed sufficiently.

[Step (2): The silicon oxide having a weight ratio with respect to the nucleus (A) of 0.001 to 10 in terms of SiO ₂ is reacted with the coated ultrafine particles obtained in (1) under the condition of pH ≧ 7. Process]
The coated ultrafine particles or sol solution obtained in the step (1) is dissolved as necessary. Subsequently, the weight ratio of the coated ultrafine particles obtained in (1) to the nucleus (A) is calculated in terms of SiO ₂ . The silicon oxide which becomes 0.001 to 10 is reacted under the condition of pH ≧ 7.

Although there is no restriction | limiting in particular as a silicon oxide used here, Colloidal silica and silicate sol are preferable. The amount to be used, the weight ratio of the nucleus (A) is 0.001 to 10 is preferable in terms of SiO ₂ is preferably 0.1 to 1. If it is in this range, that is, greater than 10, a sufficient refractive index may not be obtained. If this range is smaller than 0.001, sufficient light resistance may not be obtained.

  The pH of the reaction solution is preferably 7 or more, more preferably 8-11. What is necessary is just to adjust pH to this range suitably. If the pH is less than 7, a dense coating layer may not be formed. The pH may be adjusted appropriately by adding a basic compound. Examples of the basic compound include sodium hydroxide and potassium hydroxide.

  In this step, a solution in which silicon oxide is dissolved in water and / or an organic solvent is continuously or intermittently added to the reaction liquid containing the nuclear fine particles to react on the surface of the fine nuclear particles. It is desirable to add over 0.1 to 100 hours. Longer than this is not economically efficient. If it is shorter than this, the reaction may be insufficient.

  Although reaction temperature does not have a restriction | limiting in particular, 0-200 degreeC is preferable and 80-200 degreeC is more preferable. If it is in this range, that is, higher than 200 ° C., fine particles may aggregate. If it is less than this range, that is, 0 ° C., the reaction may not proceed sufficiently.

  Other inorganic oxides contained in the coating layer (B), that is, the coating layer containing silicon oxide, are not particularly limited as long as they do not impair the light resistance, dispersibility, and storage stability of the resulting fine particles. However, specific examples include oxides such as Al, Si, V, Fe, Zn, Zr, Nb, Mo, Sn, Sb, and W, and preferably Al, Si, Zr, Sn, and Sb. The oxide of this is mentioned.

  Moreover, as the coating layer, only the coating layer made of the two-layered silicon oxide described above is desirable, but another inorganic oxide coating layer may be provided. In this case, it is desirable to provide inside the coating layer made of the two-layered silicon oxide described above.

  The coated inorganic oxide ultrafine particles obtained by the present invention, that is, the minor axis of the crystal diameter of the double-layered silicon oxide-coated tin-modified rutile titanium oxide ultrafine particles, the major axis is 2 to 20 nm, and the average aggregated particle diameter is 10 to 10. 100 nm is preferable. If the crystal diameter is smaller than 2 nm, the originally obtained refractive index may not be obtained. If it is larger than 20 nm, light scattering may occur. If the average aggregate particle size is larger than 100 nm, the sol solution or the resin composition obtained may become cloudy and opaque.

  The weight ratio of the silicon oxide coating layer to the core fine particles obtained by the above method is 0.001 to 20 in terms of SiO2. The refractive index and light resistance of the ultrafine particles themselves can be adjusted by the amount of the coating layer. Thereby, the desired light resistance can be imparted and the refractive index can be adjusted to 1.5 to 2.8.

  The reaction product obtained as described above may be used as it is as a two-layer silicon oxide-coated tin-modified rutile-type titanium oxide ultrafine particle sol solution, or may be subjected to a desired post-treatment. That is, it can be purified by a known method such as vacuum concentration using an evaporator or ultrafiltration, and concentrated to an appropriate concentration. Centrifugation can yield a white precipitate that can be redispersed in water or other desired organic solvents. In particular, by performing ultrafiltration, it is possible to remove the ion component that causes the aggregation of the fine particles by shielding the electric double layer around the fine particles, so that the dispersion stability is improved. The aqueous sol solution in which the two-layer silicon oxide coated tin-modified rutile titanium oxide ultrafine particles are dispersed is replaced with an organic solvent such as alcohols such as methanol and cellosolves such as 2-methoxyethanol, and dispersed in the organic solvent. It is also possible to use it as a sol solution.

  Titanium oxide ultrafine particles usually have an equipotential point in the neutral region, and in the conventional production method, they are sol solutions that are stable in the acidic region. For this reason, the titanium oxide ultrafine particle sol solution produced by the conventional method has a problem that the neutral to basic flocculation causes aggregation and gelation, and the range of use is limited. Moreover, when it tried to substitute with an organic solvent, there existed a problem of causing aggregation and gelatinization and impairing stability. Furthermore, even when the dispersion medium is water, if it is concentrated to 10% by weight or more, gelation is caused, and it is difficult to obtain a sol solution dispersed at a high concentration, resulting in low productivity. By reacting the silicon oxide according to the present invention in the range of pH <7, there is no aggregation or gelation in a wide range of pH, particularly 14> pH> 3, and it is a thin film excellent in dispersibility and storage stability. A titanium oxide ultrafine particle sol solution coated with a silicon oxide layer can be obtained, and a dense and thick silicon oxide coating layer can be provided by reacting in a range of pH ≧ 7.

  In general, the surface of a titanium oxide ultrafine particle sol that is stable in an acidic region is positively charged. By reacting there under the above conditions, by selecting ultrafine particles having the opposite sign charge and smaller in size than the nuclear fine particles, heteroaggregation is caused on the surface of the nuclear fine particles, and the thin layer is more effectively and uniformly formed. It is considered that a silicon oxide film is formed, thereby imparting SiO2 characteristics to the surface of the core fine particle, and the titanium oxide ultrafine particle sol according to the present invention is stable in a wide pH range of pH = 3-14. By growing a dense and thick silicon oxide layer under basic conditions of pH ≧ 7, ultrafine particles having light resistance and weather resistance can be obtained while maintaining high dispersibility. That is, ultrafine titanium oxide particles having a two-layer structure of a coating inner layer formed at pH <7 and a coating outer layer formed at pH ≧ 7 and excellent in transparency, dispersibility, storage stability, light resistance, weather resistance, etc. A sol solution.

  With the silicon oxide coating, the concentration of the sol solution is stable over a wide range of pH even when the concentration is as high as 20% by weight or more, further 35% by weight or more in terms of solid content, and even when replaced with an organic solvent. Stable in concentration.

  The surface of the coated inorganic oxide ultrafine particles obtained by the present invention, that is, the double-layered silicon oxide-coated tin-modified rutile titanium oxide ultrafine particles is preferably treated with amines and organosilicon oxides. This greatly improves the long-term dispersion stability and compatibility of the ultrafine particles in an organic dispersion medium such as an organic solvent, resin or monomer thereof. In particular, when a dispersion medium having a relative dielectric constant smaller than that of methanol is used, it is not possible to expect dispersion stability due to electric repulsion between fine particles, and therefore it is preferable to improve the affinity by surface treatment. This improves the transparency of the resin composition. Here, the surface treatment may be any of those chemically bonded to the surface, chemical adsorption, physical adsorption and the like.

  When surface-treating with an organosilicon compound, a compound known as a silane coupling agent is suitable. Specifically, organosilicon compounds represented by the following general formulas (1) and (2) are preferable.

(R ¹ ) _a (R ² ) _b Si (OR ³ ) _(3-ab) (1)
Si (OR ³ ) ₄ (2)
(Wherein R ¹ and R ² are organic groups having an alkyl group, a halogenated alkyl group, a vinyl group, an allyl group, an acyl group, an acryloxy group, a methacryloxy group, a mercapto group, an amino group, an epoxy group, etc. (It is bonded to silicon by a —C bond. R ³ is an organic group such as an alkyl group having 1 to 8 carbon atoms, an alkoxyalkyl group, or an acyl group.)

Specific examples of R ¹ , R ² and R ^{3 in the} general formulas (1) and (2) include, for example, an organic group having an alkyl group such as a methyl group, an ethyl group, a propyl group, The organic group having a group is a chloromethyl group, a 3-chloropropyl group, etc., the organic group having an acyl group is an acetoxypropyl group, etc., and the organic group having an acryloxy group is a 3-acryloxypropyl group As the organic group having a methacryloxy group, a methacryloxypropyl group or the like is used. As the organic group having a mercapto group, a mercaptomethyl group is used. As the organic group having an amino group, a 3-aminopropyl group is used. The organic group containing an epoxy group is a 3-glycidoxypropyl group or the like, and the alkoxyalkyl group is a methoxyethyl group or the like. Can be mentioned.

  Specific examples of the compound represented by the general formula (1) include methyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, allyldimethoxysilane, allyltriethoxysilane, acetoxypropyltrimethoxysilane, 3 -Acryloxypropyldimethylmethoxysilane, methacryloxymethyltriethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyl Trimethoxysilane, (3-glycidoxypropyl) dimethylethoxysilane, (3-glycidoxypropyl) methyldimethoxysilane, (3-glycidoxypropyl) trimethoxysilane Emissions, such as trimethyl methoxy silane.

  Specific examples of the compound represented by the general formula (2) include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, and tetra-tert-. Examples include butoxysilane and tetra-sec-butoxysilane.

  Hydrolysis of the organosilicon compound represented by the general formula is carried out by adding hydrochloric acid or the like. Thereby, a part or all of the alkoxy group is hydrolyzed. Alcohols such as methanol, cellosolves such as methyl cellosolve, esters such as ethyl acetate, ethers such as tetrahydrofuran, ketones such as acetone, halogen hydrocarbons such as chloroform, hydrocarbons such as toluene and heptane, etc. Dilution may be performed.

  These may be reacted without hydrolysis, or after hydrolysis, the hydrolyzate, partial hydrolyzate, or partial condensate may be reacted with ultrafine particles. It is hydrolyzed by water remaining in the dispersion medium and water adsorbed on the ultrafine particles. Furthermore, it may be reacted with a silicone resin such as polysiloxane having a hydrolyzable group or a hydroxyl group in a condensed form thereof. These may be used alone or as a mixture.

After the (OR ³ ) group is hydrolyzed, it is preferable to cause a dehydration reaction with the —OH group on the surface of the ultrafine particles to form a Si—O—M bond, but a part thereof may remain.

  As a treatment method, a sol solution is mixed with a solvent containing an organosilicon oxide, and a catalyst is added if necessary, followed by heating for a certain time. If necessary, it is performed by a method such as removing unreacted components in the mixed solution by a method such as ultrafiltration or centrifugation.

  As the amine (s) used for the surface treatment, propylamine, diisopropylamine, butylamine, triethylamine, dodecylamine, and the like are preferably used. In order to perform surface treatment with these, for example, ultrafine particles or a sol solution is mixed in a solution such as water or alcohol, and after adding a catalyst as necessary, it is left at room temperature for a predetermined time or is subjected to heat treatment. Good.

  A polymer having the above functional group is also effective. For example, styrene resin which is amination of polystyrene, and derivatives thereof, a polymer having a hydrolyzable silicon group in the side chain of polymethyl methacrylate, a silicone resin having a hydrolyzable group or a hydroxyl group, and the like can be mentioned. The surface treatment method may be performed by the method described above.

  The amount of the surface treatment agent to be used is appropriately set in consideration of dispersibility in a binder such as an organic solvent and a resin to be used.

  Further, since the surface of the titanium oxide ultrafine particles easily reacts with carboxylic acid, acetic acid, propionic acid, acrylic acid, methacrylic acid, tartaric acid, glycolic acid, polyacrylic acid, and the like can be used. It is appropriately set in consideration of the silicon oxide coating layer.

  By this method, coated inorganic oxide ultrafine particles having a minor axis of crystal diameter, a major axis of 2 to 20 nm, and an average aggregated particle diameter of 10 to 100 nm, that is, bilayer silicon oxide-coated tin-modified rutile titanium oxide ultrafine particles are obtained. It is done. If the crystal diameter is smaller than 2 nm, the refractive index originally obtained when used in a dispersion medium or resin composition containing these may not be obtained. If it is larger than 20 nm, light scattering may occur. If the average aggregate particle size is larger than 100 nm, the resulting resin composition may become cloudy and opaque.

  The organic solvent (dispersion medium) used to disperse the ultrafine particles in the present invention is not particularly limited. Specifically, for example, alcohols such as methanol, ethanol, isopropanol, methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl Glycol ethers such as ether, esters such as ethyl acetate, ethers such as tetrahydrofuran, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, halogen hydrocarbons such as chloroform, hydrocarbons such as toluene and heptane, etc. An organic solvent is mentioned, and 2 or more types may be mixed and used.

  Furthermore, in addition to the dispersion medium as described above, it is also possible to disperse the ultrafine particles using an organic substance such as a resin monomer as a dispersion medium. As a result, the organic solvent-dispersed sol liquid can be directly cured, and the manufacturing method can be simplified. Examples thereof include monomers such as epoxy resins, acrylic resins, and silicone resins. The fine particle surface treatment is appropriately set according to the polarity of the resin monomer used. In either case, a method of replacing the dispersion medium with an evaporator or the like is employed.

  The refractive index of the coated inorganic oxide ultrafine particles obtained by the above method, that is, the bilayer silicon oxide-coated tin-modified rutile titanium oxide ultrafine particles is 1.5 to 2.8, particularly 2.0 to 2.8. Can be obtained and can be set as appropriate for each application.

  Next, the resin used in the present invention will be described. Optical resin is required to have characteristics such as colorless and transparent, low birefringence, low hygroscopicity, no hygroscopic deformation, high heat resistance in the manufacturing process and usage environment, and excellent moldability. However, as long as these are satisfied, there is no particular limitation, and conventional optical lenses (glass lenses, Fresnel lenses, pickup lenses in information recording devices such as CDs and DVDs, lenses for photographing devices such as digital cameras), optical prisms, etc. , Optical waveguides, optical fibers, thin film moldings, optical adhesives, optical semiconductor sealing materials, diffraction gratings, light guide plates, liquid crystal substrates, light reflectors, and the like may be used. For example, amorphous resin represented by acrylic resin, styrene resin, polycarbonate resin, polyester resin, olefin resin, alicyclic acrylic resin, alicyclic olefin resin, polyurethane resin, polyether resin, polyamide resin, polyimide resin A curable thermoplastic resin or a curable resin such as an epoxy resin or an unsaturated polyester resin is preferable.

  Specifically, acrylic resin such as methyl methacrylate (PMMA), styrene resin as polystyrene (PS), styrene and acrylonitrile copolymer (SAN), styrene and methyl methacrylate copolymer, polyester resin, etc. Examples thereof include polyethylene terephthalate and polyethylene naphthalate, and examples of the olefin resin include polymethylpentene (TPX).

  Polycarbonate resin is a polymer produced by the reaction of bisphenols and carbonates such as phosgene. The alicyclic acrylic resin is an acrylic resin in which an aliphatic cyclic hydrocarbon such as tricyclodecane is introduced into an ester substituent, and examples thereof include polycyclomethacrylate tricyclodecane and polymethacrylate norbornane. It has excellent low birefringence, low hygroscopicity, and heat resistance, and is used for pickup lenses, imaging lenses, and the like. An alicyclic olefin resin is a product in which a sterically rigid alicyclic group is introduced into the main chain of an olefin polymer, has excellent heat resistance and low hygroscopicity, and is used for lenses such as in-vehicle CD players. It has been.

  A polyether resin, a polyamide resin, a polyimide resin, or the like, which is a polymer in which a benzene ring, an aliphatic ring, or the like is connected through an ether bond, can also be used.

  In addition, a resin obtained by polymerizing a monomer containing an element having a large atomic number such as sulfur or a halogen element, for example, a thiourethane bond formed by thermal polymerization of a thiol compound and an isocyanate compound that are used in spectacle lens applications is formed. It is also possible to use a resin obtained by polymerizing and curing the obtained resin, episulfide, or epithiosulfide compound.

  For semiconductor encapsulant use, thermosetting epoxy resins, silicone resins, and the like are preferably used.

  The method for producing the resin composition in the present invention is not particularly limited, and any method known in the art may be used as long as it is a method used to uniformly mix the fine particles and the resin.

  Specifically, for example, a resin and an ultrafine particle sol solution or an ultrafine particle powder are prepared independently, and then both are mixed or kneaded. Any method such as a polymerization method or a method of preparing ultrafine particles under conditions in which a resin prepared in advance is present can be employed.

  From the viewpoint of dispersion stability of ultrafine particles, a method of obtaining a resin composition by uniformly mixing an ultrafine particle sol solution and a resin-dissolved solution and removing the solvent, or dispersing ultrafine particles in a resin monomer Preferred examples include a method of preparing a resin composition directly by polymerization and curing.

  The resin composition of the present invention can be subjected to conventionally known molding processes such as extrusion molding, injection molding, vacuum molding, blow molding, and compression molding, and various molded articles such as disks and films can be obtained.

  There is no restriction | limiting in particular in the quantity of the said resin matrix component used in this invention, Although it sets suitably according to a use, Ultrafine particle content contained in a resin composition is 0.1 to 90 weight% Is preferred. More preferably, it is 10 to 70% by weight. If it is smaller than this, there is a possibility that the characteristics of the fine particles such as an increase in the refractive index may not be imparted. When larger than this, flexibility, toughness, etc. may be insufficient.

  The ultrafine particles and sol solution used in the present invention are preferably coated inorganic oxide ultrafine particles, that is, only double-layered silicon oxide-coated tin-modified rutile titanium oxide ultrafine particles, It can also be used in combination with other inorganic oxide ultrafine particles that are inferior in the effect of improving the rate. Examples thereof include colloidal silica and antimony oxide colloid.

  In addition, the resin composition of the present invention requires an ultraviolet absorber, an antioxidant, a heat stabilizer, a light stabilizer, an antistatic agent, a release agent, a plasticizer, a disperse dye, a pigment, a dye, a dye improver, and the like. Depending on the case, it is also possible to add any additive.

  Therefore, the coated inorganic oxide ultrafine particles according to the present invention, that is, the bilayer silicon oxide-coated tin-modified rutile titanium oxide ultrafine particles have a high refractive index and are excellent in transparency, dispersibility, light resistance, light resistance and the like. Therefore, the resin composition formed using the ultrafine particles has a high refractive index, transparency, light resistance, weather resistance, heat resistance, molding processability, etc., and can arbitrarily adjust the refractive index. It is suitably used for optical members.

  There is no restriction | limiting in particular in the optical member comprised including the resin composition of this invention, For example, it can use for all or one part of a member. More specifically, optical lenses (glass lenses, Fresnel lenses, pickup lenses in information recording devices such as CDs and DVDs, lenses for photographing devices such as digital cameras), optical prisms, optical waveguides, optical fibers, thin film moldings, optical Adhesives for optical semiconductors, sealing materials for optical semiconductors, diffraction gratings, light guide plates, liquid crystal substrates, light reflecting plates, materials for high refractive index optical members such as antireflection materials, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

(Preparation of bilayer silicon oxide-coated tin-modified rutile-type titanium oxide ultrafine particle sol solution)
[Production Example 1]
Tin tetrachloride pentahydrate 0.27 g was charged into a 100 ml eggplant type flask, dissolved in 50 ml of ion-exchanged water, and 5 ml of a hydrochloric acid aqueous solution of titanium oxide chloride (containing 15 wt% Ti) was added. The pH of the solution was -0.1. (Ti concentration of Ti = 0.45, Sn / Ti = 0.03) The mixture was stirred with a magnetic stirrer and heated at 50 ° C. for 1 hour to obtain a white precipitate. Centrifugation was performed, and the white precipitate was collected and redispersed in ion-exchanged water. Ultrafiltration was performed to obtain a sol solution having a solid content of 2% by weight. This solid was subjected to powder X-ray diffraction measurement and electron microscope observation. When powder X-ray diffraction measurement was performed after hot-air drying at 120 ° C. for 2 hours, it was a titanium oxide rutile type. The crystal diameter was calculated from the half-value width of the diffraction peak using the Debye-Scherrer equation. As a result, the average crystal diameter was 5 nm for the minor axis and 8 nm for the major axis, respectively. The observation with an electron microscope was performed using a transmission electron microscope, and a solution obtained by dropping a diluted sol solution onto a mesh was observed at a magnification of 200,000 times and 2 million times. As a result, it was a rutile type titanium oxide having an average aggregated particle size of 23 nm. The elemental molar ratio of Sn / Ti by inductively coupled plasma analysis was 0.02.

  After 2500 g of this tin-modified rutile type titanium oxide ultrafine particle sol solution was adjusted to pH = 3, it was heated to 80 ° C. 125 g of a 2% by weight aqueous silicon oxide solution was added dropwise over 1 hour, and the mixture was further heated for 30 minutes. After cooling to room temperature, a 1 mol / l sodium hydroxide aqueous solution was added to form a sol solution. While the temperature was raised to 80 ° C. and maintained at pH = 9, 625 g of a 2 wt% aqueous silicon oxide solution was added dropwise over 2 hours and further heated for 4 hours. The mixture was purified by ultrafiltration to obtain a 2 wt% sol solution. The weight ratio of coating layer / fine particles by inductively coupled plasma analysis was = 0.13 / 1. After repeating the operation of adding methanol and concentrating with a rotary evaporator, a 20 wt% methanol-dispersed sol solution was obtained.

[Production Example 2]
Next, sulfuric acid was added to 100 g of the 20 wt% methanol-dispersed sol solution prepared in Production Example 1 to adjust the pH to 5, 1 g of 3-methacryloxypropyltrimethoxysilane was added, and the mixture was heated at 50 ° C. The operation of adding propylene glycol monomethyl ether and concentrating with an evaporator was repeated to obtain a 20 wt% propylene glycol monomethyl ether dispersed sol.

[Production Example 3]
Next, after repeating the operation of concentrating the 20 wt% propylene glycol monomethyl ether dispersion sol prepared in Production Example 2 by adding methyl isobutyl ketone with an evaporator, 0.2 g of dodecylamine was added and heated at 50 ° C. to obtain 20 wt. % Methyl isobutyl ketone dispersion sol.

[Production Example 4]
The same operation as in Production Example 1 was carried out except that 0.9 g of tin tetrachloride pentahydrate was used in Production Example 1. (Feed Ti concentration = 0.45, Sn / Ti = 0.1) When the solid content of the obtained sol solution was analyzed in the same manner as in Production Example 1, the element molar ratio of Sn / Ti was 0.06. It was a rutile type titanium oxide having an average crystal diameter of 5 nm for the minor axis and 8 nm for the major axis and an average aggregated particle diameter of 20 nm. The weight ratio of coating layer / fine particles was = 0.13 / 1. After repeating the operation of adding methanol and concentrating with a rotary evaporator, a 20 wt% methanol-dispersed sol solution was obtained.

[Production Example 5]
A 20 wt% propylene glycol monomethyl ether dispersed sol was obtained in the same manner as in Production Example 2 except that the 20 wt% methanol dispersed sol liquid prepared in Production Example 4 was used.

[Production Example 6]
A 20 wt% methyl isobutyl ketone dispersed sol was obtained in the same manner as in Production Example 3 except that the 20 wt% propylene glycol monomethyl ether dispersed sol liquid prepared in Production Example 5 was used.

(Synthesis of rutile titanium oxide)
[Comparative Production Example 1]
It carried out like manufacture example 1 except not adding a tin tetrachloride pentahydrate. The white precipitate obtained did not redisperse. When analyzed in the same manner, it was a rutile type titanium oxide having an aggregate particle diameter of 200 nm or more. Although the operation of adding methanol and concentrating with a rotary evaporator was performed, gelation and precipitation were generated on the way.

(Preparation of anatase-type titanium oxide ultrafine particle sol solution)
[Comparative Production Example 2]
To 2 L of ion-exchanged water, 20 ml of a hydrochloric acid aqueous solution of titanium oxide chloride (Ti content: 15% by weight) was added and heated at 60 ° C. for 6 hours. After cooling to room temperature, it was concentrated and deionized by ultrafiltration to obtain a sol solution having a solid content of 2% by weight. When the solid content of the obtained sol solution was analyzed in the same manner as in Production Example 1, it was anatase-type titanium oxide having an average of 5 nm on both the minor axis and the major axis. After repeating the operation of adding methanol and concentrating with a rotary evaporator, a 20 wt% methanol-dispersed sol solution was obtained.

(Preparation of zirconium oxide-coated anatase-type titanium oxide ultrafine particle sol solution)
[Comparative Production Example 3]
20 ml of a hydrochloric acid aqueous solution of titanium oxide chloride (Ti content 15% by weight) was added to 2 L of ion-exchanged water and heated at 60 ° C. for 6 hours. 50 g of an aqueous solution in which 32 g of zirconium oxide chloride octahydrate was dissolved was dropped, heated to 90 ° C., and heated for 1 hour. After cooling to room temperature, ultrafiltration was performed. After cooling to room temperature, it was concentrated and deionized by ultrafiltration to give a 2 wt% sol solution. When the solid content of the obtained sol solution was analyzed in the same manner as in Example 1, it was anatase-type titanium oxide having an average of 5 nm on both the minor axis and the major axis. The composition of the zirconium oxide-coated anatase-type titanium oxide ultrafine particles was zirconium oxide / titanium oxide weight ratio = 0.85 / 1 in terms of oxide. After repeating the operation of adding methanol and concentrating with a rotary evaporator, a 20 wt% methanol-dispersed sol solution was obtained.

[Comparative Production Example 4]
A commercially available antimony pentoxide ultrafine particle sol solution was used as a 20 wt% methanol-dispersed sol solution.

(Preparation of resin composition)

  10.5 g (solid content 2.1 g) of the 20 wt% dispersion sol obtained in Production Example 2 and 1.2 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.) Made) and then 3.0 g of ethyl cellosolve was added. Furthermore, 0.17 g of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TMDPO) as a photoinitiator and a Si-based surfactant (trade name FZ-2110 manufactured by Nippon Unicar Co., Ltd.) were added, Stir well. After removing the solvent, a metal halide lamp (strength 120 W / cm) was irradiated for 60 seconds to produce a 2 mm thick film (1-2). Similarly, films (1-3), (1-5), and (1-6) were prepared using the sol liquids obtained in Production Examples 3, 5, and 6. All were colorless and transparent.

(Preparation of resin composition)

  It is obtained in Production Example 3 by dissolving 1.2 g of a pellet of purified copolymer of bisphenol A and epichlorohydrin (Sigma Aldrich Japan Co., Ltd.) in 10 g of butanol: toluene (1: 1) mixed solvent. Then, 6.5 g of 20% by weight methyl isobutyl ketone-dispersed sol solution was added and stirred. The cast was dried at 120 ° C. to prepare a 2 mm thick film (2-3). The film was colorless and transparent. Moreover, it shape | molded at 180 degreeC using the hot press machine, and was set as the 1 cm square resin composition. Similarly, a film (2-6) and a 1 cm square resin composition were prepared using the sol solution obtained in Production Example 6. All were colorless and transparent.

[Comparative Example 1]
Except that the sol solution obtained in Comparative Production Examples 1, 2, 3, and 4 was used, the same procedure as in Example 1 was performed, and the films (1-1 ′), (1-2 ′), and (1-3 ′) ), (1-4 ′).

  About the resin composition prepared by the said method, refractive index, light resistance, and transparency were evaluated as shown below. The results are shown in Table 1.

(A) Light resistance: The occurrence of cracks after irradiation of the obtained resin composition for 500 hours by a solar simulator (Type: sss-252161-ER manufactured by Ushio Electric Co., Ltd.), and the degree of yellowing and browning at all. Judgment was made by △ and × in order of increasing degree, with no being.

(B) Refractive index measurement:
Resin composition: The dissolved resin composition solution was applied on a quartz substrate by spin coating to a film thickness of about 700 mm, and the coating film dried with hot air was an automatic wavelength scanning ellipsometer M-150 (manufactured by JASCO Corporation). ) Was used to measure the refractive index at 550 nm.

(C) Transparency: Judged visually.

＊フィルム１−１’は白濁膜となり測定不可であった。

* The film 1-1 ′ was a cloudy film and could not be measured.

  As shown in Table 1, by applying the two-layer silicon oxide coating method found by the present inventors to tin-modified rutile-type titanium oxide ultrafine particles, a high refractive index and more efficient than the conventional metal oxide coating It can be seen that the photocatalytic action of titanium oxide is suppressed. Thereby, it turns out that the transparent resin composition excellent in the high refractive index and light resistance is obtained.

  ADVANTAGE OF THE INVENTION According to this invention, it has the outstanding transparency and high refractive index, and can provide the novel resin composition used as an optical member. Specifically, high refractive index coated inorganic oxide ultrafine particles with excellent transparency, dispersibility, light resistance, weather resistance, etc., that is, bilayer silicon oxide coated tin-modified rutile titanium oxide ultrafine particles are transparent at high concentration A transparent resin composition dispersed in an organic substance such as a resin can be provided.

  The resin composition of the present invention has characteristics such as a high refractive index and a high light transmittance due to the presence of rutile-type titanium oxide ultrafine particles, and has a high light resistance due to the two-layer silicon oxide coating layer. Optical lenses (glass lenses, Fresnel lenses, pickup lenses in information recording devices such as CDs and DVDs, lenses for photographing devices such as digital cameras), optical prisms, optical waveguides, optical fibers, thin film moldings, optical adhesives, light It can be used as a material for a high refractive index optical member such as a sealing material for a semiconductor, a diffraction grating, a light guide plate, a liquid crystal substrate, a light reflection plate, and an antireflection material.

Claims (9)

  Inorganic oxidation composed of a coating layer (B) containing silicon oxide with an inorganic oxide ultrafine particle containing titanium oxide having a rutile crystal structure having a refractive index of 1.5 to 2.8 as a nucleus (A) A resin composition comprising coated inorganic oxide ultrafine particles having a material coating layer. The rutile type titanium oxide ultrafine particles in the inorganic oxide ultrafine particles containing titanium oxide having the rutile type crystal structure of the nucleus (A),
In the presence of a tin compound having a molar ratio of tin to titanium (Sn / Ti) of 0.001 to 2, a titanium compound aqueous solution having a Ti concentration of 0.07 to 5 mol / l is reacted in a pH range of −1 to 3. Obtained tin-modified rutile titanium oxide ultrafine particles having a Sn / Ti composition molar ratio of 0.001 to 0.5,
The coating layer containing silicon oxide (B) is of a two-layer coating type, the inner layer has a coating layer obtained by the step (1), and the outer layer is obtained by the step (2), _2. The resin composition according to claim 1, wherein the oxide coating layer is a coated inorganic oxide ultrafine particle, wherein the weight ratio of the oxide coating layer is 0.001 to 20 in terms of SiO2.
(1) Step of reacting silicon oxide having a weight ratio with respect to the nucleus (A) of 0.001 to 10 in terms of SiO ₂ with the nucleus (A) under the condition of pH <7 (2) with respect to the nucleus (A) The step of reacting the silicon oxide having a weight ratio of 0.001 to 10 in terms of SiO ₂ with the coated ultrafine particles obtained in (1) under the condition of pH ≧ 7   The resin composition according to claim 1 or 2, wherein a minor axis and a major axis of the crystal diameter of the coated inorganic oxide ultrafine particles are 2 to 20 nm.   The resin composition according to any one of claims 1 to 3, wherein an average aggregate particle diameter of the aggregate composed of the coated inorganic oxide ultrafine particles is 10 to 100 nm.   The resin composition according to claim 1, wherein a sol obtained by dispersing the coated inorganic oxide ultrafine particles in water or an organic solvent is used.   6. The resin composition according to claim 1, wherein the surface of the coated inorganic oxide ultrafine particles is treated with an organosilicon compound or an amine.   The resin composition according to any one of claims 1 to 6, which has a refractive index of 1.5 to 2.8.   An optical member comprising the resin composition according to claim 1.   The optical member according to claim 8, wherein the optical member is used for an optical lens, an optical prism, an optical waveguide, an optical fiber, a thin film molding, an optical adhesive, or an optical semiconductor sealing material.