JP2005076002A - Organic-inorganic composite material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material having a good optical property containing an organic material and an inorganic material.
An organic-inorganic composite material comprising an organic-inorganic organic resin, an aluminum compound, and at least one metal species selected from the group consisting of rare earth elements.
[Selection figure] None

Description

  The present invention relates to an organic-inorganic composite material and a method for producing the same. In particular, the present invention provides an optical material having a high refractive index and low dispersion as compared with an optical material used for a conventional plastic lens or the like.

  In the field of optical materials, resin lenses can be molded at low cost, so they are used for eyeglass lenses, plastic lenses such as camera lenses, prisms, and the like, and are now indispensable materials. As an optical lens material, polymethyl methacrylate resin (PMMA resin) is used as an optical application and a transparent molding material because of its excellent transparency, surface hardness, and heat resistance. Further, methyl methacrylate-styrene copolymer resin (MS resin) obtained by copolymerizing styrene with methyl methacrylate is used as an optical plastic having a high refractive index.

MS resin is less expensive than PMMA resin and has a high refractive index and excellent moldability, but is a material with large dispersion. In addition, polycarbonate, amorphous polyolefin resin, and 9,9-bis [4- (2-hydroxyethoxy) phenyl] fluorene copolymer, which are plastics used for optical applications, also have a higher refractive index than PMMA. However, the applications are limited because they are highly dispersed materials.
On the other hand, in order to improve heat resistance and hardness, which are weak points of organic polymer materials, proposals have been made on composite materials of organic substances and inorganic substances. For example, an organic-inorganic composite material in which an amide group-containing nonreactive polymer is uniformly dispersed in a three-dimensional microstructure of a metal oxide formed by a sol-gel method has been proposed (Patent Document 1).

Also proposed is an inorganic / organic hybrid material for lenses in which a copolymer of (meth) acrylate monomers, an organosilicon compound, and a polymer having a urethane bond are dispersed as a polymer in a SiO ₂ -based three-dimensional microstructure. Yes. (Patent Documents 2 to 4)

Many of the methods for obtaining these organic-inorganic composite materials use silicon compounds as starting materials, such as silicon alkoxides and their derivatives, polysilanes, etc. When using metals other than silicon, use metal alkoxides and their derivatives. It is common. Therefore, the types of metals are limited to metals that are relatively easy to handle metal alkoxides such as Ti, Ge, Al, and Zr.
As a result, there is a problem that the refractive index and dispersion characteristics of the organic-inorganic composite material to be manufactured are limited.
Japanese Patent No. 2574049 JP-A-7-90155 JP 7-97499 A JP-A-7-97511

  An object of the present invention is an inorganic-organic composite material having a high refractive index and a low dispersion, and a method for producing the same, and an inorganic-organic composite material having various metal components that are effective in enhancing optical properties and the production thereof The method is the subject.

The object of the present invention can be solved by an organic-inorganic composite material containing an organic-inorganic organic resin, an aluminum compound, and at least one metal species selected from the group consisting of rare earth elements. it can.
An organic-inorganic composite using a boehmite sol as a raw material for an aluminum compound in a method for producing an organic-inorganic composite material containing an organic resin, an aluminum compound, and at least one metal species selected from the group consisting of rare earth elements It is a manufacturing method of material.
In the method for producing an organic-inorganic composite material, an aqueous solution in which a salt containing at least one kind of rare earth element is dissolved is used for producing boehmite sol.
The boehmite sol is hydrolyzed by adding an aqueous solution containing 20 to 500 mol of water in a molar ratio to 50 to 90 ° C. with respect to the aluminum alkoxide or derivative thereof, and further peptized by adding an acid. It is a manufacturing method of an organic inorganic composite material.
The organic-inorganic composite material having a step of replacing an aqueous solvent with an organic solvent before mixing a solution obtained by mixing boehmite sol and at least one metal species selected from the group consisting of rare earth elements with a vinyl monomer. It is a manufacturing method.
In the method for producing an organic-inorganic composite material, the rare earth element is at least one selected from La, Y, Gd, and Ta.

  The present invention is an organic-inorganic composite material containing a vinyl monomer capable of radical polymerization, an aluminum compound, and at least one metal species selected from the group consisting of rare earth elements, and uses boehmite as the aluminum compound By doing so, an optical material excellent in refractive index and dispersion characteristics can be provided.

The present invention is an organic-inorganic composite material containing an organic resin, an aluminum compound, and at least one rare earth element.
The organic-inorganic composite material can be produced by blending an organic component and an inorganic component. Generally, however, a composition in which an organic solvent is mixed is used as the organic component, and the inorganic component is a metal salt or the like. Is used to introduce metal components.

However, when organic resin synthetic resins and rare earth salts, oxides, etc. are blended and mixed, it is difficult to evenly disperse the rare earth, causing agglomeration, resulting in non-uniform appearance and white turbidity and scattering. It was inconvenient to use as an optical element.
Therefore, the present invention has found that by adding an aluminum compound to a rare earth compound to be mixed with a synthetic resin that is an organic component, the rare earth compound can be evenly dispersed and a transparent organic-inorganic composite material can be obtained. is there.

  The reason why the effects of the present invention can be obtained is unknown, but the presence of an aluminum compound takes a form in which a rare earth oxide or a part thereof is substituted with an organic chain such as a vinyl group, and a covalent bond, an ionic bond, or a hydrogen bond. It is speculated that this contributes to the homogeneous mixing of the organic components.

Below, the manufacturing method of the organic inorganic composite material of this invention is described.
As a raw material of the aluminum compound of the present invention, an alkoxide represented by Al (OR) ₃ (R: alkyl group), (RO) _3-n AlL _n (R is an alkyl group, n = 1 to 2, L is Derivatives represented by acetylacetona group, ethoxyacetylacetona group and the like, and metal salts such as Al (NO ₃ ) ₃ .9H ₂ O are exemplified.
Boehmite sol is an easily peptized particle obtained by a method such as heating immediately after hydrolysis of amorphous aluminum monohydroxide obtained by hydrolysis of the above compound as an aluminum compound raw material, A sol containing a substance represented by the molecular formula of AlO (OH).

In addition, since boehmite sol has aluminum and a hydroxyl group, it easily has a covalent bond or a hydrogen bond with an organic resin component at room temperature and has good dispersibility. When an alkoxide such as aluminum isopropoxide or a derivative thereof is selected as the organic group of the boehmite sol, it has an Al—O bond as a molecular structure from the beginning, and thus is easily crosslinked.
The boehmite sol is obtained by adding an aqueous solution mainly composed of relatively high temperature water of 10 ° C. or higher and lower than 100 ° C., preferably 50 ° C. to 90 ° C., to 30 ° C. or higher and lower than 200 ° C., preferably 50 ° C. to 100 ° C. In an oil bath or the like for 1 hour or longer, preferably 10 to 100 hours. It is also effective to perform reflux heating at this time. As the amount of water to be used, it is necessary to use a relatively large amount of water of 20 to 500 in molar ratio with respect to the aluminum compound.
By these operations, the aluminum hydroxide is peptized to be converted into uniform fine particles to become a sol containing boehmite having a low viscosity. The concentration of boehmite contained in the sol may be 1 × 10 ⁻⁶ mol / l or more, preferably 1 × 10 ⁻⁴ mol / l or more.

In the present invention, the rare earth includes Y, Ta and 15 lanthanoids, that is, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. it can. Among these, Y, La, Gd, and Ta are transparent in the visible range, and are particularly preferable when used as an imaging optical element.
In order to introduce them, water-soluble compounds of inorganic acid salts such as rare earth chlorides and nitrates and organic acid salts such as acetates can be used.
By using a water-soluble compound, an arbitrary amount of rare earth component can be introduced.
Further, when boehmite is produced, a rare earth compound is dissolved in water at a relatively high temperature in advance and used for producing boehmite, whereby a boehmite sol containing rare earth at a high concentration can be produced.

  Examples of the organic resin used for the organic-inorganic composite material include acrylate resin, polyolefin, polystyrene, polycarbonate, ABS resin, polyester, and the like, epoxy, unsaturated ester, acrylate, urethane, ether, and the like. Preferably, what can be added in a monomer state is good. Examples of the monomer include vinyl monomers.

  Examples of vinyl monomers include methacrylic acid esters such as methyl methacrylate, acrylic acid esters, aromatic vinyl monomers such as methacrylic acid and styrene, vinyl cyanide monomers such as acrylonitrile, acrylic acid, and maleic acid. , Maleic acid esters, itaconic acid and itaconic acid esters, N-alkylmaleimides, N-phenylmaleimide (PMI) s and the like.

  Preferred monomers include methyl methacrylate, ethyl methacrylate, propylene methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, phenyl methacrylate and other methacrylic acid alkyl esters, methyl acrylate, ethyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dodecyl acrylate, phenyl acrylate, acrylic acid alkyl esters such as benzyl acrylate, side chain alkyl-substituted styrene such as styrene and α-methylstyrene, nuclear alkyl-substituted styrene such as vinyltoluene, bromostyrene, Halogenated styrene such as chlorostyrene, vinyl naphthalene, etc. Group vinyl monomers, vinyl cyanide monomers such as acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, α-chloroacrylonitrile, other maleic acid, maleic acid esters, itaconic acid and itaconic acid esters, N- Alkyl maleimides, N-phenylmaleimide (PMI) and the like.

In particular, in order to obtain the characteristics of high refractive index and low dispersion, the high refractive index is not particularly important as a polymer component, but rather it is important that it is low dispersion. A monomer that becomes a low-dispersion polymer having an Abbe number ν _d of 50 or more when polymerized alone is effective. Therefore, as a monomer component, the methacrylic acid alkylesters and acrylic acid alkylesters which do not contain an aromatic are preferable. In addition, a derivative into which fluorine is introduced, such as trifluoromethacrylate, is preferable because the polymer polymer has low dispersion.
Further, alcohol, glycol, acetic acid, acetylacetonate and the like may be added to the metal salt solution in order to disperse the metal salt in the resin without aggregating the metal salt. Particularly, those which form a complex with a metal salt such as acetic acid and acetylacetonate are effective when the metal salt is contained in a high concentration.

  It is also effective to include components such as silica, titania and zirconia in addition to the essential components for the purpose of improving water absorption and hardness. As these components, alkoxides and derivatives thereof can be used. For example, in the case of silica, there are tetraethoxysilane, methyltriethoxysilane, 2-hydroxyethyl methacrylate (HEMA), those having a vinyl group, and those having an ethylene oxide group. Since 2-hydroxyethyl methacrylate has a hydrophilic group, it has good affinity through hydrogen bonding with boehmite sol.

  In the method using the boehmite sol of the present invention, since water is excessively present, the compatibility with the organic resin may be poor. As a method for solving this problem, it is also effective to replace the solvent in the boehmite sol with an organic solvent after the boehmite sol is prepared. As this means, for example, boehmite sol can be easily mixed with an organic resin component by removing water by continuously replacing the boehmite sol with an alcohol such as methanol or n-propanol at about 20 ° C. under reduced pressure. It is effective to obtain fine particles and mix them with an organic resin.

  Further, a polymerization assistant such as a polymerization polymerization initiator, a molecular weight regulator, a dispersant and other solvents is added to these components and polymerized. As a polymerization initiation method, any of a heating method and a method of adding a polymerization initiator can be employed.

As the polymerization initiator, an organic peroxide or an azo initiator can be used together with an emulsifier or a surfactant.
Specific examples of the initiator of the azo compound include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2′-methylbutyronitrile), 1,1′azobis ( Azonitriles such as cyclohexane-1-carbonitrile), and organic peroxides include peroxyesters such as t-hexylperoxyisopropyl monocarbonate and t-hexylperoxy-2-ethylhexanoate, and lauroyl par It can be selected from diacyl peroxides such as oxide, peroxyketals such as 1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane, and the like.

Further, molecular weight regulators used for regulating the fluidity of the resin in these polymerizations include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and monomonomers such as 1-methyl-4-isopropylidenecyclohexene. Examples thereof include terpenoids and styrene dimers such as 2,4-diphenyl-4-methyl-1 ′ pentene.
Further, antioxidants, ultraviolet absorbers, anti-coloring agents, antistatic agents, fluorescent paints, mold release agents and other stabilizers may be added for use.

In the resin thus obtained, the rare earth element introduced as an aluminum compound or metal compound forms a coordinate bond or hydrogen bond with an oxygen atom or the like in the resin, and the resin is removed even after removing excess moisture and solvent. It is involved in the refractive index and dispersion characteristics depending on the type of metal species and the amount introduced.
The obtained organic-inorganic composite material can be used to produce an optical element or the like by a molding method such as photocuring, press molding, or injection molding.
Hereinafter, the present invention will be described with reference to examples and comparative examples.

La ₂ O ₃ and 10mol%, Al ₂ O ₃ of 10 mol%, to produce an organic-inorganic composite materials in the compounding ratio of 80 mol% of methyl methacrylate.
Aluminum isopropoxide: 1 mol part of lanthanum acetate 1.5 hydrate: 1 mol part of water is dissolved in 400 mol part of water to perform hydrolysis by adding 80 ° C warm water, and then 1N nitric acid is added. Further, the mixture was stirred at 80 ° C. for 76 hours to peptize to prepare a boehmite sol containing lanthanum.

Next, the boehmite sol was refluxed at 55 ° C. for 24 hours with a vacuum evaporator to remove water. Methyl methacrylate (MMA) and an ultraviolet curing agent (Irgacure 500 manufactured by Ciba Specialty Chemicals) were added to and mixed with the boehmite sol in a molar ratio of lanthanum of 1: 8.
The obtained liquid mixture was transferred to a UV-transmissive mold, purged with nitrogen to remove oxygen, irradiated with an ultraviolet lamp with an irradiation intensity of 0.6 W / cm ² for 24 hours, and then heated to 140 ° C. at 2 ° C. An organic-inorganic composite material was obtained by maintaining the temperature for 2 hours after raising the temperature at / min.

  From the obtained organic-inorganic composite material, a diameter of 50 mm and a thickness of 2. An Omm flat plate molded article was prepared, and the light transmittance, refractive index, and Abbe number of 400 nm to 800 nm were measured. The light transmittance was 88%, the refractive index was 1.603, and the Abbe number was 62.5.

Comparative Example 1
An organic-inorganic composite material was prepared at a compounding ratio of 10 mol% La ₂ O ₃ , 10 mol% SiO ₂ , and 80 mol% methyl methacrylate.
Methyltrimethoxysilane (MTMOS): 1 mol part, phenyltrimethoxysilane (PTMOS): 1 mol part, 3-methacryloxypropyltrimethoxysilane (MPTMOS): 1 mol part, and lanthanum acetate 1.5 hydrate: 1 200 mol parts of water in which mol parts were dissolved were stirred and mixed at room temperature for 5 hours. To this solution, a solution of trimethoxysilane (TMOS): 1 mol part and methanol was added, and the mixture was stirred and mixed for 72 hours. Obtained.

Next, the obtained sol was refluxed at 55 ° C. for 24 hours with a vacuum evaporator to remove water. Next, methyl methacrylate (MMA) and an ultraviolet curing agent (Irgacure 500 manufactured by Ciba Specialty Chemicals) were added to the sol and mixed.
The obtained liquid mixture was transferred to a UV-transmissive mold, purged with nitrogen to remove oxygen, irradiated with an ultraviolet lamp with an irradiation intensity of 0.6 W / cm ² for 24 hours, and then heated to 140 ° C. at 2 ° C. An organic-inorganic composite material was obtained by maintaining the temperature for 2 hours after raising the temperature at / min, but it was opaque and could not be used as an optical element.

An organic-inorganic composite material of 20 mol% Y ₂ O ₃ , 20 mol% Al ₂ O ₃ and 60 mol% MMA was produced.
Aluminum isopropoxide: 1 mol part of yttrium chloride hexahydrate: 1 mol part of water dissolved in 150 mol parts of water was added to carry out hydrolysis, followed by addition of 1N nitric acid. Peptization was carried out by stirring at 80 ° C. for 76 hours to prepare a boehmite sol containing yttrium.

Next, the boehmite sol was refluxed at 55 ° C. for 24 hours with a vacuum evaporator to substantially remove water. Methyl methacrylate (MMA) and an ultraviolet curing agent (Irgacure 500 manufactured by Nagase Sangyo Co., Ltd.) were added to and mixed with the boehmite sol at a molar ratio of lanthanum of 1: 8.
The obtained liquid mixture was transferred to a UV-transmissive mold, purged with nitrogen to remove oxygen, irradiated with an ultraviolet lamp with an irradiation intensity of 0.6 W / cm ² for 24 hours, and then heated to 140 ° C. at 2 ° C. An organic-inorganic composite material was obtained by maintaining the temperature for 2 hours after raising the temperature at / min.

  A flat plate molded product having a diameter of 50 mm and a thickness of 2.0 mm was prepared for evaluation from the obtained organic-inorganic composite material, and light transmittance, refractive index, and Abbe number of 400 nm to 800 nm were measured. The light transmittance was 86%, the refractive index was 1.634, and the Abbe number was 56.3.

An organic-inorganic composite material of 30 mol% La ₂ O ₃ , 15 mol% Al ₂ O ₃ , 10 mol% SiO _2, and 45 mol% monomer for forming an organic tree machine resin was produced.
Aluminum isopropoxide: 1 mol part of lanthanum chloride heptahydrate: 1 mol part of water was added to 80 mol of hot water dissolved in 150 mol parts of water, followed by hydrolysis. Peptization was performed by stirring at 80 ° C. for 76 hours to prepare a boehmite sol containing lanthanum.

  Next, n-propanol was added to the boehmite sol and heated to reduce the water to the azeotropic point to obtain a boehmite n-propanol solution. Trimethoxysilane and 2-hydroxyethyl methacrylate were added to the produced boehmite sol and refluxed at 55 ° C. for 24 hours with a vacuum evaporator to remove n-propanol.

To the obtained sol, neopentyl glycol diacrylate and trimethylolpropane triacrylate were added, La ₂ O ₃ : 30 mol%, Al ₂ O ₃ : 15 mol%, SiO ₂ : 10 mol%, monomer for forming an organic tree machine resin: While mixing so as to be 45 mol, an ultraviolet curing agent (Irgacure 500 manufactured by Ciba Specialty Chemicals) was added and mixed for 30 minutes. After removing the solvent from the resulting solution with a vacuum evaporator, it was transferred to an ultraviolet light transmissive mold, purged with nitrogen to remove oxygen, and then irradiated with an ultraviolet lamp with an irradiation intensity of 0.6 W / cm ² for 24 hours. The organic-inorganic composite material was obtained by keeping the temperature up to 140 ° C. at 2 ° C./min and holding for 2 hours.

  From the obtained organic-inorganic composite material, a diameter of 50 mm and a thickness of 2. An Omm flat plate molded article was prepared, and the light transmittance, refractive index, and Abbe number of 400 nm to 800 nm were measured. The light transmittance was 86%, the refractive index was 1.684, and the Abbe number was 53.3.

  The present invention is an organic-inorganic composite material containing a vinyl monomer capable of radical polymerization, an aluminum compound, and at least one metal species selected from the group consisting of rare earth elements, and uses boehmite as the aluminum compound By doing so, it is easy to have a covalent bond or hydrogen bond with the organic resin, the dispersibility is improved, and an optical material excellent in refractive index and dispersion characteristics can be provided.

Claims (6)

An organic-inorganic composite material comprising an organic resin, an aluminum compound, and at least one metal species selected from the group consisting of rare earth elements. In the method for producing an organic-inorganic composite material containing an organic resin, an aluminum compound, and at least one metal species selected from the group consisting of rare earth elements, boehmite sol is used as a raw material for the aluminum compound. A method for producing an organic-inorganic composite material. The method for producing an organic-inorganic composite material according to claim 2, wherein an aqueous solution in which a salt containing at least one kind of rare earth element is dissolved is used for producing boehmite sol. Boehmite sol is hydrolyzed by adding an aqueous solution containing 20 to 500 moles of water in an aluminum alkoxide or derivative thereof to a temperature of 50 to 90 ° C., and further peptized by adding an acid. The method for producing an organic-inorganic composite material according to claim 2. Before mixing a solution in which boehmite sol and at least one metal species selected from the group consisting of rare earth elements are mixed with a vinyl monomer, the method has a step of replacing an aqueous solvent with an organic solvent. The manufacturing method of the organic inorganic composite material of Claim 2. 6. The method for producing an organic-inorganic composite material according to claim 1, wherein the rare earth element is at least one selected from La, Y, Gd, and Ta.