JP6432269B2 - Organic acid-containing zirconia fine particle dispersion, surface-modified zirconia fine particle dispersion, method for producing the same, and resin composite composition - Google Patents

Description

  The present invention relates to an organic acid-containing zirconia fine particle dispersion, a surface-modified zirconia fine particle dispersion, a production method thereof, and a resin composite composition.

  Conventionally, optical members used in various devices such as various camera lenses, microlenses of image sensors, optical pickup lenses such as DVDs, LED sealing materials, etc. have basic optical characteristics such as high light transmittance and high refractive index. Is needed. These optical members include optical lenses using resins such as polymethyl methacrylate (PMMA), polycyclohexyl methacrylate, and polycarbonate (PC), and sealing materials using silicone resins and epoxy resins. In order to satisfy required optical properties such as high light transmittance and high refractive index, composites of various refractive resins such as zirconia and titania with various resins have been proposed (see, for example, Patent Document 1 and Patent Document 2). ). In addition, in order to obtain composites of such high refractive index fine particles and various resins as described above, there is a technique in which the surface of hydrophilic high refractive index fine particles is surface-treated with a surface modifier in accordance with various hydrophobic resins. It has been proposed (see, for example, Patent Document 3 and Patent Document 4).

By the way, a composite of high refractive index fine particles and a resin as used in an optical member is dispersed as small as possible in the resin so as to prevent a decrease in light transmittance and a handling property due to an increase in viscosity. It is necessary to modify the surface of the high refractive index fine particles uniformly and at a high density so that they are dispersed with a particle size and do not interact with each other.
As such a modification method, a method in which a compound containing a branched hydrocarbon group having 6 or more carbon atoms and a carboxyl group and a silane coupling agent or the like are used in combination (for example, see Patent Document 5), or two or more types A method of performing a two-step treatment with a surface modifier (for example, see Patent Document 6) has been proposed.

Japanese Patent No. 4704175 JP 2007-103708 A Japanese Patent No. 5167582 Japanese Patent No. 5540458 Japanese Patent No. 5030694 Japanese Patent No. 5012230

However, in a method such as Patent Document 5, since a compound containing a branched hydrocarbon group having 6 or more carbon atoms and a carboxyl group is present on the surface of the high refractive index fine particles, particularly during heat curing or high illumination. Discoloration due to deterioration or the like of branched chain hydrocarbon groups having 6 or more carbon atoms was observed in the usage environment, resulting in problems such as extremely poor heat resistance and light resistance, and limited resin selection and applications.
Further, the method as described in Patent Document 6 is very effective as a method for highly modifying the surface of the high refractive index fine particles, but the high refractive index fine particles are aggregated in the initial modification, In order to uniformly modify the surface of the high refractive index fine particles, for example, it is necessary to highly disperse the zirconia fine particle dispersion before the treatment with the modifying agent.

  The present invention has been made to solve the above problems, and has a surface-modified zirconia fine particle dispersion having a high refractive index, high transparency, and high handling properties, a method for producing the same, and the surface-modified zirconia fine particles. An object of the present invention is to provide an organic acid-containing zirconia fine particle dispersion capable of producing a dispersion, and a resin composite composition using these dispersions.

The present inventors have adsorbed an organic acid on the surface of zirconia fine particles, and if the organic acid is replaced with an organic surface modifier, a surface-modified zirconia fine particle dispersion having a high refractive index, high transparency, and high handling properties. It was found that a resin composite having excellent heat resistance and light resistance can be finally obtained by removing the free organic acid as an organic acid compound.
That is, the present invention is as follows.

[1] An organic acid, zirconia fine particles having an average dispersed particle diameter of 1 nm or more and 20 nm or less, and a dispersion medium,
The organic acid-containing zirconia fine particle dispersion, wherein the organic acid is 0.001 g or more and 0.05 g or less with respect to a surface area of 1 m ² of the zirconia fine particles.

[2] The organic acid includes at least any of formic acid, acetic acid, propionic acid and butyric acid,
The organic acid-containing zirconia fine particle dispersion liquid according to [1], wherein the dispersion medium contains at least water.
[3] A surface-modified zirconia fine particle dispersion containing surface-modified zirconia fine particles whose surface is modified with an organic surface modifier, a dispersion medium, and an organic acid compound,
The average dispersed particle diameter of the zirconia fine particles in the surface-modified zirconia fine particles is 1 nm or more and 20 nm or less,
The organic surface modifier is at least one selected from the group consisting of an alkoxysilane compound, a siloxane compound and a titanium coupling agent,
The surface-modified zirconia fine particle dispersion, wherein the content of the organic acid compound is less than 3% by mass with respect to the mass of the zirconia fine particles.
[4] The surface-modified zirconia fine particle dispersion according to [3], wherein the organic acid compound is at least one of ammonium formate, ammonium acetate, ammonium propionate, and ammonium butyrate.

[5] A resin composite composition comprising mixing the surface-modified zirconia fine particle dispersion according to [3] or [4] above and a resin raw material, and then removing the solvent.

[6] A method for producing a surface-modified zirconia fine particle dispersion as described in [3] or [4] above, which comprises the following steps.
(1) A step of adding an organic surface modifier to the organic acid-containing zirconia fine particle dispersion described in [1] or [2], and replacing the organic acid on the surface of the zirconia fine particles with the organic surface modifier.
(2) A step of converting (converting) the organic acid contained into the organic acid compound by adding ammonia or amine to the dispersion after step (1) and adjusting the pH to 7.5 or higher.
(3) A step of subjecting the dispersion after step (2) to a solid-liquid separation treatment and washing the resulting surface-modified zirconia fine particle cake.
(4) A step of drying the surface-modified zirconia fine particle cake obtained in step (3) and then redispersing it in a dispersion medium.

  According to the present invention, a surface-modified zirconia fine particle dispersion having a high refractive index, high transparency, and high handling properties, a method for producing the same, and an organic acid-containing zirconia capable of producing the surface-modified zirconia fine particle dispersion A fine particle dispersion and a resin composite composition using these dispersions can be provided.

Hereinafter, the organic acid-containing zirconia fine particle dispersion, the surface-modified zirconia fine particle dispersion, the production method thereof, and the resin composite composition of the present invention will be described.
In addition, the following description is specifically described in order to make the gist of the invention better understood, and does not limit the present invention unless otherwise specified.

[1. Organic acid-containing zirconia fine particle dispersion]
The organic acid-containing zirconia fine particle dispersion of this embodiment is a dispersion containing an organic acid, zirconia fine particles, and a dispersion medium.
The content of the organic acid is 0.001 g or more and 0.05 g with respect to the surface area of 1 m ^{2 of the} zirconia fine particles.

  As the organic acid, a water-soluble fatty acid (monocarboxylic acid) is suitably used. Formic acid, acetic acid, propionic acid, butyric acid, and the like are preferable, and formic acid, acetic acid, and propionic acid are particularly preferable. These organic acids may be used alone or in combination of two or more.

Here, the reason for containing the organic acid is that the carboxylic acid contained in the organic acid is hydrogen-bonded with the hydroxyl group on the surface of the zirconia fine particles and adsorbed on the surface of the zirconia fine particles. Organic acids also have high adsorption efficiency on the surface of zirconia fine particles. By ideally covering this surface, the interaction between particles due to hydroxyl groups on the surface of zirconia is prevented, the average dispersed particle size is small, and dispersion stability is reduced. This is because a high dispersion liquid can be made.
In addition, when an organic acid is contained, by generating a zeta potential on the surface of the zirconia fine particles by lowering the pH of the dispersion, an electric repulsive force is generated between the dispersed zirconia fine particles, and the dispersion having high dispersion stability Can be made.
Furthermore, the organic acid adsorbed on the zirconia surface reduces the thickness of the electric double layer, resulting in a decrease in the viscosity of the system and the easier passage of particles through the microfilter. Therefore, zirconia fine particle dispersion having an average dispersed particle diameter of 1 nm or more and 20 nm or less can be stably produced.
Further, when an organic acid is contained, there is an advantage that the organic acid adsorbed on the zirconia surface can be easily removed by alkali as described later.

  Here, formic acid, acetic acid, propionic acid and butyric acid are preferred as organic acids because they are easily dissolved in water, which is the main solvent in the synthesis of zirconia fine particles, and can easily be substituted with a surface modifier described later. Because it happens.

The content of the organic acid is 0.001 g or more and 0.05 g or less, preferably 0.002 g or more and 0.040 g or less, preferably 0.003 g or more and 0 or less, per 1 m ² of the surface area of the zirconia fine particles. More preferably, it is 0.035 g or less.
Here, the reason why the content of the organic acid is limited to 0.001 g or more and 0.05 g or less with respect to the surface area of 1 m ² of the zirconia fine particles is that the surface of the zirconia fine particles is ideally covered if it is less than 0.001 g. This is because the electric repulsive force between the zirconia fine particles becomes weak and the dispersion stability of the dispersion is poor. Further, since the electric double layer of the particles becomes thick, it becomes difficult to pass through the microfilter pores. On the other hand, if it exceeds 0.05 g, the organic acid (for example, acetic acid) with respect to the zirconia particles becomes too much, and the progress of the substitution reaction with the surface modifier is hindered. Further, it is difficult to remove an organic acid (for example, acetic acid) compound described later.

The reason why the average dispersed particle size of the zirconia fine particles is limited to 1 nm or more and 20 nm or less is that when the average dispersed particle size is less than 1 nm, the crystallinity of the primary particles forming the dispersed particles becomes poor, and the refractive index, etc. This is because it becomes difficult to express the particle characteristics. On the other hand, when the average dispersed particle diameter exceeds 20 nm, the translucency is lowered when the resin composite is used. The average dispersed particle size is preferably 2 nm or more and 15 nm or less.
The average primary particle size of the zirconia fine particles necessary for obtaining such a dispersed particle size is not particularly limited as long as it is smaller than the above dispersed particle size, but is preferably 1 nm or more and 15 nm or less, preferably 4 nm or more and 11 nm or less. It is more preferable that In order to make the average primary particle size within the above range, for example, it may be controlled by adjusting the temperature and time when the zirconia fine particle precursor is fired using an electric furnace.

  The reason why the present invention is limited to zirconia as the fine particle material is that it has excellent transparency to visible light and high refractive index, high light transmittance, high thermal stability, high hardness, low water absorption, low photocatalytic activity, and high weather resistance. It is because it is preferable to show a property, solvent resistance, etc.

On the other hand, the dispersion medium basically contains one or more of water and a water-soluble organic solvent.
As said organic solvent, a lower alcohol is preferable and methanol and ethanol are especially preferable. Examples of other organic solvents include ethylene glycol, dimethylacetamide, and N-methylpyrrolidone.

The content of the zirconia fine particles in the organic acid-containing zirconia fine particle dispersion is preferably 0.1% by mass or more and 50% by mass or less, and more preferably 1% by mass or more and 30% by mass or less.
When the content is 0.1% by mass or more and 50% by mass or less, the zirconia fine particles can take a good dispersion state. Also, by being in this range, the yield in the step of substituting the organic acid with the organic surface modifier described later is good, and gelation and aggregation precipitation are difficult to occur, and the characteristics as a dispersion liquid are good. This is because it can be maintained.

[2. Surface-modified zirconia fine particle dispersion]
The surface-modified zirconia fine particle dispersion of this embodiment is a dispersion containing surface-modified zirconia fine particles whose surface is modified with an organic surface modifier, a dispersion medium, and an organic acid compound.

  The organic surface modifier is preferably an organic compound having a C—C bond or a siloxane bond, and such an organic compound is selected from the group of alkoxysilane compounds, siloxane compounds, and titanium coupling agents. One or two or more are preferably used. Of these surface modifiers, a silane coupling agent is particularly preferable as the alkoxysilane compound, and a modified silicone is preferable as the siloxane compound.

  Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-propyltrimethoxysilane, n-butyltriethoxysilane, and n-hexyltri. Methoxysilane, n-hexyltriethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, p-styryltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3- Examples include acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane. It is.

Examples of the modified silicone include alkoxy-modified silicone, carboxy-modified silicone, alcohol-modified silicone, polyether-modified silicone, epoxy-modified silicone, mercapto-modified silicone, amino-modified silicone, (meth) acrylate-modified silicone, dimethyl silicone, and methylhydrogen silicone. Can be mentioned.
Use of a modified silicone having a vinyl group and / or a functional group bonded to a silicon atom is preferred because the functional group bonded to the vinyl group and / or silicon atom contributes to a chemical reaction when the resin is cured.
In the present specification, “(meth) acrylate” means both methacrylate and acrylate.

  Examples of the titanium coupling agent include isopropyl triisostearoyl titanate, isopropyl di (meth) acryl isostearoyl titanate, isopropyl tri (dodecyl) benzenesulfonyl titanate, neopentyl (diallyl) oxy-tri (dioctyl) phosphate titanate, neopentyl ( Diallyl) oxy-trineodecanoyl titanate and the like.

The mass ratio of the modified portion of the surface-modified zirconia particles is preferably 5% by mass or more and 200% by mass or less, more preferably 10% by mass or more and 100% by mass or less, based on the total amount of particles. More preferably, it is 20 mass% or more and 100 mass% or less.
When the mass ratio of the modified portion is 5% by mass or more and 200% by mass or less, the compatibility of the zirconia particles with the resin is facilitated, and the refractive index of the zirconia fine particles is dragged by the refractive index of the surface modifier. Moreover, it can prevent that the refractive index of zirconia microparticles | fine-particles falls.

  As will be described later, examples of the organic acid compound obtained by the reaction between an organic acid and ammonia include ammonium formate, ammonium acetate, ammonium propionate, and ammonium butyrate. Ammonium formate, ammonium propionate, and ammonium acetate are particularly preferred because of their ease of removal during washing.

The content of the organic acid compound is less than 3% by mass with respect to the mass of the zirconia fine particles, but is preferably 0.001% by mass or more and less than 3% by mass, 0.001% by mass or more and 1% by mass. % Or less, more preferably 0.001% by mass or more and 0.5% by mass or less.
When the content of the organic acid compound is 3% by mass or more, the surface-modified zirconia fine particle dispersion is mixed with the resin raw material, and then the solvent is removed to prepare the resin composite composition. By decomposing or changing the quality, there is a risk that the resin composite composition may be reduced in mass or discolored. The organic acid compound is very effective in that it plays a catalytic role for promoting the reaction of the secondary surface treatment agent described later. This can be seen from the fact that when the content of the organic acid compound is less than 0.001 mass%, the cause is not clear, but the efficiency of the secondary surface treatment may vary.

The dispersion medium is preferably an organic solvent.
Examples of the organic solvent include alcohols such as methanol, ethanol, 2-propanol, butanol, and octanol, ethyl acetate, butyl acetate, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and γ-butyrolactone. Esters such as diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, acetone, Methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, cyclohexanone, etc. Amides, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, and amides such as dimethylformamide, N, N-dimethylacetoacetamide and N-methylpyrrolidone are preferably used. One of these solvents or Two or more kinds can be used.

The dispersion may further contain a resin raw material such as a liquid resin monomer or a liquid resin oligomer.
As the liquid resin monomer, acrylic or methacrylic monomers such as methyl acrylate and methyl methacrylate, and epoxy monomers are preferably used.
Moreover, as said liquid resin oligomer, a urethane acrylate oligomer, an epoxy acrylate oligomer, an acrylate oligomer, etc. are used suitably.

The content of the surface-modified zirconia fine particles in the surface-modified zirconia fine particle dispersion is preferably 10% by mass to 80% by mass, and more preferably 10% by mass to 50% by mass.
A zirconia fine particle can be made into a favorable dispersion state because the content rate of a zirconia fine particle is 10 mass% or more and 80 mass% or less. Moreover, the effect as a zirconia microparticle is maintained, and it becomes difficult to produce gelatinization and aggregation precipitation, and the characteristic as a dispersion liquid can be maintained.

This surface-modified zirconia fine particle dispersion may contain other inorganic oxide particles, a dispersant, a dispersion aid, a coupling agent, an antistatic agent, a resin polymer, and the like as long as the characteristics are not impaired. Other inorganic oxide particles include titanium oxide (TiO ₂ ), zinc oxide (ZnO), cerium oxide (CeO ₂ ), tin oxide (SnO ₂ ), antimony-added tin oxide (ATO), tin-added indium oxide (ITO) ) And the like.

  Further, like the organic acid-containing zirconia fine particle dispersion according to the present invention, the average dispersed particle size of the zirconia fine particles in the surface-modified zirconia fine particles is 1 nm or more and 20 nm or less, and the meaning, preferred range, and the like are also the same.

[3. Resin composite composition]
The resin composite composition of the present embodiment is an uncured resin composite composition obtained by mixing the surface-modified zirconia fine particle dispersion according to the present invention and a resin raw material, and then removing the dispersion medium.
The resin may be a resin having transparency with respect to light in a predetermined wavelength band such as visible light, near-infrared light, near-ultraviolet light, etc., for example, thermosetting for forming these transparent resins. Curable resin raw materials such as curable resin, light (electromagnetic wave) curable by visible light, ultraviolet light, infrared light, and the like, and electron beam curable by electron beam irradiation are preferably used. A thermoplastic resin can also be used as the resin having transparency.

  Examples of the transparent resin include acrylates such as polymethyl methacrylate (PMMA) and polycyclohexyl methacrylate, polycarbonate (PC), polystyrene (PS), polyether, polyester, polyarylate, polyacrylate, polyamide, phenol- Formaldehyde (phenolic resin), diethylene glycol bisallyl carbonate, acrylonitrile / styrene copolymer (AS resin), methyl methacrylate / styrene copolymer (MS resin), poly-4-methylpentene, norbornene polymer, polyurethane, epoxy, Silicone, etc. are mentioned, and in particular, it contains one or more selected from the group of silicone resins, epoxy resins, (meth) acrylate resins, and polycarbonate resins. It is preferable.

  Here, acrylate resin, silicone resin, and epoxy resin which are thermosetting resins among said transparent resin are demonstrated in detail.

(Acrylate resin)
As the acrylate resin, various monofunctional acrylates and / or polyfunctional acrylates are used, and one or more of these are used. Specific examples of the monofunctional acrylate and the polyfunctional acrylate will be described below.

  (A) Aliphatic monofunctional (meth) acrylates include alkyl (meth) acrylates such as butyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, methoxypropylene glycol (meth) acrylate, ethoxydiethylene glycol ( Examples include alkoxyalkylene glycol (meth) acrylates such as (meth) acrylate, N-substituted acrylamides such as (meth) acrylamide, and N-butoxymethyl (meth) acrylamide.

  (B) As aliphatic polyfunctional (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) ) Acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polybutanediol Di (meth) acrylate, alkylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylol propylene Penta (meth) acrylates such as tri (meth) acrylate pentaerythritol tetra (meth) acrylate such as tri (meth) acrylate, tetra (meth) acrylate dipentaerythritol (monohydroxy) pentaacrylate such as di-trimethylolpropane tetraacrylate And (meth) acrylate modified with ethylene oxide or propylene oxide.

  (C) Among the alicyclic (meth) acrylates, the monofunctional type includes cyclohexyl (meth) acrylate, and the polyfunctional type includes dicyclopentadienyl di (meth) acrylate.

  (D) Among aromatic (meth) acrylates, monofunctional types include phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and the like. Examples of the mold include diacrylates such as bisphenol A di (meth) acrylate, bisphenol F di (meth) acrylate, and the like.

(E) Examples of the polyurethane (meth) acrylate include polyurethane ether (meth) acrylate and polyester (meth) acrylate.
(F) Examples of the epoxy (meth) acrylate include bisphenol A type epoxy acrylate and novolac type epoxy acrylate.

  Moreover, as a radical polymerization initiator used suitably, lauroyl peroxide, benzoyl peroxide, di-t-butyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, Peroxide polymerization initiators such as t-butyl peroxypivalate, t-butyl peroxybenzoate and t-butyl peroxyacetate, or azo polymerization initiators such as 2,2′-azobisisobutyronitrile Is mentioned.

(Silicone resin)
The silicone resin is preferably composed of at least the following components (a) to (c).
(A) Organopolysiloxane in which at least two functional groups bonded to silicon atoms in one molecule are alkenyl groups (b) Whether at least two functional groups bonded to silicon atoms in one molecule are hydrogen atoms Or a linear organopolysiloxane (c) hydrosilylation catalyst in which both ends of the molecular chain are blocked with hydrogen atoms

(A) As an alkenyl group in a component, a vinyl group, an allyl group, a pentenyl group, a hexenyl group etc. are mentioned, Especially a vinyl group is preferable.
Examples of functional groups bonded to silicon atoms other than alkenyl groups include alkyl groups such as methyl, ethyl, propyl, and butyl groups, aryl groups such as phenyl and tolyl groups, benzyl groups, and phenethyl groups. Examples thereof include an aralkyl group, and a methyl group is particularly preferable.

(B) Functional groups bonded to silicon atoms other than hydrogen atoms in the component include alkyl groups such as methyl group, ethyl group, propyl group and butyl group, aryl groups such as phenyl group and tolyl group, benzyl group and phenethyl. And an aralkyl group such as a group, and a methyl group is particularly preferable.
In addition, the content of the component (b) is preferably an amount such that the hydrogen atoms are in the range of 0.1 to 10 mol with respect to 1 mol of the total alkenyl groups contained in the component (a). The amount is preferably in the range of 1 to 5 mol, and more preferably in the range of 0.5 to 2 mol.

The catalyst for hydrosilylation reaction of component (c) is a catalyst for promoting a hydrosilylation reaction between an alkenyl group in component (a) and a hydrogen atom bonded to a silicon atom in component (b). Examples of such a catalyst include platinum-based catalysts, rhodium-based catalysts, palladium-based catalysts, and the like, and platinum-based catalysts are particularly preferable.
Examples of the platinum-based catalyst include fine platinum powder, chloroplatinic acid, platinum-olefin complex, platinum carbonyl complex and the like, and chloroplatinic acid is particularly preferable.

  The amount of component (c) used is an amount capable of promoting the curing of the composition, that is, hydrosilyl of an alkenyl group in component (a) and a hydrogen atom bonded to a silicon atom in component (b). There is no particular limitation as long as it is an amount capable of promoting the chemical reaction, and specifically, the metal atom in the present component is 0.01 to 500 ppm by mass relative to the present composition. It is preferably within the range, and more preferably within the range of 0.01 to 50 ppm.

By setting the amount to be used in the range of 0.01 to 500 ppm, the present composition is sufficiently cured, and problems such as coloring are hardly generated in the obtained cured product.
About this silicone resin, unless the objective of this invention is impaired, you may contain a heat-resistant agent, dye, a pigment, a flame retardance imparting agent, etc. as other arbitrary components.

(Epoxy resin)
Epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, biphenyl type epoxy resin, and other bifunctional glycidyl ether type epoxy resins, phenol novolac type Polyfunctional glycidyl ether type epoxy resin such as epoxy resin, orthocresol novolac type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, tris-hydroxyphenylmethane type epoxy resin, tetraphenylolethane type epoxy resin, tetraglycidyl diamino Diphenylmethane type epoxy resin, triglycidyl isocyanurate type epoxy resin, aminophenol type epoxy resin, aniline type epoxy resin, toluidine type epoxy Glycidyl amine type epoxy resins such as a resin is preferably used.

  As a curing agent for epoxy resin, any of polyaddition type, catalyst type and condensation type can be used. For example, diaminodiphenylmethane, diaminodiphenylsulfone, polyamide, dicyandiamide, diethylenetriamine, triethylenetetramine, hexahydro anhydride Examples include phthalic acid, methyltetrahydrophthalic anhydride, and phenol resin.

  In addition, an antioxidant, a release agent, a coupling agent, an antistatic agent, an inorganic filler, etc. may be added to the acrylate resin, silicone resin, and epoxy resin as long as the characteristics are not impaired. Good.

The content of the zirconia fine particles in the resin composite composition is preferably 10% by mass to 80% by mass, and more preferably 30% by mass to 80% by mass.
When the content is 10% by mass or more and 80% by mass or less, an effective improvement in refractive index is recognized, and the characteristics (flexibility and specific gravity) of the resin itself can be maintained.

[4. Manufacturing method of each aspect]
Next, a method for producing a dispersion and a resin composite composition according to this embodiment will be described.

(Method for producing zirconia fine particles)
The method for producing zirconia fine particles according to the present embodiment is not particularly limited as long as crystalline zirconia fine particles can be obtained with an average primary particle size of 1 nm or more and 15 nm or less. For example, as disclosed in Japanese Patent No. 5434665. Any known technique can be used.
However, when a hydrochloric acid compound such as Japanese Patent No. 5434665 is used as a starting material, it is preferable to remove the chlorine content to 100 ppm or less in order to prevent corrosion of equipment and members. Chlorine removal can be performed with, for example, an ultrafiltration device.

(Method for producing organic acid-containing zirconia fine particle dispersion)
The organic acid-containing zirconia fine particle dispersion according to this embodiment is obtained by mixing zirconia fine particles having an average dispersed particle diameter of 1 nm or more and 20 nm or less, an organic acid, and a dispersion medium, and performing a dispersion treatment using a bead mill or the like. Can be obtained.
Further, as disclosed in JP-A-2009-298658, an organic acid may be added after dispersing zirconia fine particles with an inorganic acid such as hydrochloric acid.

(Method for producing surface-modified zirconia fine particle dispersion)
The method for producing a surface-modified zirconia fine particle dispersion according to this embodiment includes the following steps.
(1) A step of adding an organic surface modifier to the organic acid-containing zirconia fine particle dispersion according to the present invention and replacing the organic acid on the surface of the zirconia fine particles with the organic surface modifier.
(2) A step of adding organic acid to the organic acid compound by adding ammonia or amine to the dispersion liquid after step (1) and adjusting pH to 7.5 or higher.
(3) A step of subjecting the dispersion after step (2) to a solid-liquid separation treatment and washing the resulting surface-modified zirconia fine particle cake.
(4) A step of drying the surface-modified zirconia fine particle cake obtained in step (3) and then redispersing it in a dispersion medium.
Hereinafter, each step will be described.

Step (1):
As described above, organic acids such as formic acid and acetic acid are adsorbed to the zirconia fine particles contained in the organic acid-containing zirconia fine particle dispersion according to this embodiment, and the zirconia fine particles are used as a dispersion medium in a form close to a single particle. Is distributed.

  When an organic surface modifier is added to this organic acid-containing zirconia fine particle dispersion, the organic acid adsorbed on the surface of the zirconia fine particles easily undergoes a substitution reaction with the organic surface modifier, and the surface of the zirconia fine particles is gradually modified with the organic surface The surface is modified with an agent, and the surface becomes more hydrophobic, and the surface-modified zirconia fine particles aggregate and gradually settle.

Here, when there is no organic acid adsorbed on the surface of the zirconia fine particles, the hydroxyl groups on the surface of the zirconia fine particles interact with each other as the zirconia fine particles are aggregated to form a strong aggregate. The reaction does not proceed and the zirconia fine particles finish the modification reaction in an incomplete surface modification state, and only a dispersion liquid inferior to the dispersion state after redispersion described later can be obtained. In addition, such incomplete surface-modified zirconia fine particles are exposed to a large amount of hydroxyl groups on the surface, and when the resin composite composition is used, the viscosity increases due to the interaction between the particles and the resin raw material. It becomes a factor which reduces handling property remarkably.
On the other hand, when there is an organic acid adsorbed on the surface of the zirconia fine particles, the zirconia fine particles form a loose agglomerate because there are no groups on the surface that cause an interaction even when agglomerated, so surface modification reaction between the overlapping particles also occurs. Zirconia fine particles with an ideal surface modification state are obtained that are not easily inhibited. For this reason, the dispersion liquid which is excellent in the dispersion state in redispersion described later is obtained.

Step (2):
In the method for producing a surface-modified zirconia fine particle dispersion according to this embodiment, ammonia or an amine is added to a dispersion in which a zirconia fine particle surface-modified with an organic surface modifier and a solvent are mixed, and the pH is set to 7. By adjusting to 5 or more, the reaction of the organic surface modifier is promoted, and the organic acid adsorbed on the surface of the zirconia fine particles remaining without being replaced with the organic surface modifier is easily removed as an ammonium salt. Can do.
In addition, when surface-modifying the zirconia microparticles with an organic surface modifier, for example, a method described in Japanese Patent No. 5176380 can be given as a method for adding ammonia.

  At this stage, even if the organic acid adsorbed on the surface of the zirconia fine particles is removed, there is steric hindrance due to the organic surface modifier. ,No problem.

The reason why the pH adjusted by adding ammonia or amine is limited to 7.5 or more is that if the pH is less than 7.5, the organic acid adsorbed on the surface of the zirconia fine particles cannot be sufficiently removed, and the resin complex is produced by the remaining organic acid. This is because the organic acid is later desorbed or denatured by heat or light, resulting in a decrease in mass, deformation, or discoloration of the resin composite.
The amine is an aliphatic amine such as methylamine, ethylamine, propylamine, butylamine, hexylamine, decylamine, tridecylamine, dodecylamine, octylamine, nonylamine, dimethyldodecylamine, dimethylhexadecylamine, dimethyloctadecylamine. Among them, ammonia is preferable from the viewpoint of handleability.

Step (3):
The said process is a process of performing a solid-liquid separation process to the dispersion liquid after a process (2), and performing the washing process to the obtained surface modification zirconia fine particle cake.
For the washing treatment (removal of organic acid compound) of the surface-modified zirconia fine particle cake after solid-liquid separation, it is preferable to use a solvent such as water, lower alcohols such as methanol and ethanol.

  The content of the organic acid compound after washing is less than 3% by mass with respect to the mass of the zirconia fine particles, preferably 0.001% by mass or more and less than 3% by mass, 0.001% by mass or more and 1% by mass or less. Is more preferable, and 0.001 mass% or more and 0.5 mass% or less are further more preferable.

Step (4):
The said process (4) removes volatile components, such as a water | moisture content, from the surface modification zirconia fine particle cake obtained by the process (3) mentioned above, makes it easy to disperse | distribute to a dispersion medium, and removes the free organic acid and ammonia. Process.

Although it does not specifically limit in drying of a surface modification zirconia fine particle cake, It is performed using drying apparatuses, such as an evaporator, a warm air dryer, and a vacuum heating dryer.
The drying temperature is preferably 100 ° C. or higher and 250 ° C. or lower. By setting the temperature to 100 ° C. or more and 250 ° C. or less, it is possible to prevent a large amount of non-volatile water from remaining and to improve the dispersibility in the dispersion medium and the dispersion stability. Further, the surface modifier is denatured by heat, and it is possible to prevent dispersibility, deterioration of dispersion stability, discoloration, and the like.
In addition, the above-mentioned dispersion medium can be appropriately used. The concentration of the surface-modified zirconia fine particles in the dispersion after dispersion is preferably 1% by mass or more and 70% by mass, and more preferably 1% by mass or more and 50% by mass.

(Secondary surface treatment process)
In the method for producing a surface-modified zirconia fine particle dispersion according to this embodiment, a secondary surface treatment may be performed in accordance with the characteristics of the resin raw material to be combined. About the method of secondary surface treatment, it can carry out by the method of patent 5012230 gazette. Further, a tertiary surface treatment may be further performed after the secondary surface treatment.

(Resin composite composition and resin composite production method)
The resin composite composition according to this embodiment is produced by stirring and mixing the surface-modified zirconia fine particle dispersion according to the present invention and a resin raw material using a mixer or the like, and removing the solvent by vacuum drying or the like.
The resin composite according to the present embodiment can be produced using the resin composite composition according to the present invention. In the method for producing the resin composite, the resin composition according to the present invention may be filled in a mold or a package and cured. The curing method is not particularly limited as long as it is appropriately selected according to the resin raw material to be used, the curing catalyst, and the like. For example, a heat curing method by heating, a photocuring method by irradiation with ultraviolet rays, or the like may be used. Typical examples of the shape include a molded body in which a minute convex lens portion is formed, an LED sealing material filled in a cup-shaped package, and the like.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.

[Preparation of zirconia fine particles]
To a zirconium salt solution in which 2615 g of zirconium oxychloride octahydrate was dissolved in 40 L of pure water, dilute ammonia water in which 344 g of 28% ammonia water was dissolved in 20 L of pure water was added with stirring to prepare a zirconia precursor slurry.
Next, an aqueous sodium sulfate solution in which 300 g of sodium sulfate was dissolved in 5 L of pure water was added to this slurry with stirring. The amount of sodium sulfate added at this time was 30% by mass with respect to the zirconia-converted value of zirconium ions in the zirconium salt solution.

Next, this mixture was dried in the air at 130 ° C. for 24 hours using a dryer to obtain a solid.
Next, this solid material was pulverized with an automatic mortar and then baked in the air at 500 ° C. for 1 hour using an electric furnace.
Next, the fired product is put into pure water, stirred to form a slurry, washed using a centrifuge, and after sufficiently removing the added sodium sulfate, dried in a dryer, Zirconia fine particles ZR1 were produced.
When the crystal system of the zirconia fine particles ZR1 was examined using an X-ray diffractometer, it was confirmed to be tetragonal zirconia.
Next, a transmission electron microscope (TEM) image was taken, the particle diameter of any 10 particles reflected in the TEM image was measured, and the average value was calculated as the average primary particle diameter. As a result, the zirconia fine particles ZR1 The average primary particle size was 5 nm.
Next, as a result of measuring the specific surface area by the BET method, the specific surface area of the zirconia fine particles ZR1 was 150 m ² / g.

[Preparation of organic acid-containing zirconia fine particle dispersion]
Example 1
After stirring and mixing 50 g of zirconia fine particles ZR1, 15 g of acetic acid and 935 g of ion-exchanged water to disperse the zirconia fine particles, coarse particles were removed with a microfilter (polysulfonic acid film) having a pore diameter of 50 nm to obtain an acetic acid-containing zirconia fine particle dispersion. Produced.

(Example 2)
50 g of zirconia fine particles ZR1, 250 g of acetic acid, and 700 g of ion-exchanged water were stirred and mixed to disperse the zirconia fine particles, and then the coarse particles were removed with a microfilter (polysulfonic acid film) having a pore diameter of 50 nm. A zirconia fine particle dispersion was prepared.

Example 3
A formic acid-containing zirconia fine particle dispersion of Example 3 was prepared in the same manner as in Example 1 except that the acetic acid of Example 1 was changed to formic acid.

(Example 4)
A propionic acid-containing zirconia fine particle dispersion of Example 4 was prepared in the same manner as in Example 1 except that the acetic acid of Example 1 was changed to propionic acid.

(Comparative Example 1)
After stirring and mixing 50 g of zirconia fine particles ZR1, 5 g of acetic acid and 945 g of ion-exchanged water to disperse the zirconia fine particles, coarse particles were removed with a microfilter (polysulfonic acid film) having a pore diameter of 50 nm, and acetic acid contained in Comparative Example 1 was contained. A zirconia fine particle dispersion was prepared.

Average primary particle size, BET specific surface area of zirconia fine particles ZR1 used in Examples 1 to 4 and Comparative Example 1, amount of acetic acid per 1 m ² of zirconia fine particle surface area in organic acid-containing zirconia fine particle dispersion, average dispersed particle size, filter The number of passes was measured. These results are shown in Table 1.

The measuring method of the amount of organic acid per 1 m ² of zirconia fine particle surface area in the organic acid-containing zirconia fine particle dispersion, the dispersed particle size, and the filter pass amount is as follows.

(1) an organic acid of the organic acid weight zirconia fine surface area 1 m ² per per zirconia fine surface area 1 m ² was calculated from the following equation.
“Amount of organic acid per 1 m ^{2 of} zirconia fine particle surface area” = “Amount of organic acid” / (“Amount of zirconia fine particles” × “BET specific surface area”)

(2) Average dispersed particle size Using a dynamic light scattering particle size distribution measuring device (manufactured by Malvern), the particle size distribution of the sample prepared with the zirconia fine particle content in the zirconia dispersion (Z1) being 1% by mass is used. The average dispersed particle size was determined from the measurement results.
(3) Filter pass amount The amount of acetic acid-containing zirconia fine particle dispersion that can be processed without clogging was measured with a microfilter having a pore diameter of 50 nm.

According to these evaluation results, the acetic acid-containing zirconia fine particle dispersions of Examples 1 and 2 and the formic acid-containing zirconia fine particle dispersions and the propionic acid-containing zirconia fine particle dispersions of Examples 3 and 4 were average dispersed. The total amount (1000 ml) of the acetic acid-containing zirconia fine particle dispersion sample having a sufficiently small particle size and a filter pass amount was successfully filtered.
In contrast, the acetic acid-containing zirconia fine particle dispersion of Comparative Example 1 was clogged with a filter pass amount of 280 ml, so that the coarse particles that could not be dispersed remained, and the electric double layer passed through the filter thickly even when dispersed. It was found that there was a significant amount of particles that did not.

[Production of surface-modified zirconia fine particle dispersion and resin composite composition]
(Example 5)
To 500 g of the acetic acid-containing zirconia fine particle dispersion of Example 1, 150 g of a methanol solution in which 12.5 g of isobutyltrimethoxysilane was dissolved as a primary surface modifier was added, and the surface was modified by stirring at 60 ° C. for 3 hours.

Subsequently, aqueous ammonia was added to obtain a dispersion adjusted to pH 9.
Next, the surface-modified zirconia fine particle cake was recovered from the dispersion by solid-liquid separation.
The recovered surface-modified zirconia fine particle cake was washed three times with ion-exchanged water and then dried at 120 ° C. for 2 hours to obtain surface-modified zirconia fine particles.
Next, 10 g of trimethoxy-modified alkylpolysiloxane (degree of polymerization: about 30) as a secondary surface treatment agent and 70 g of toluene as a dispersion medium are added to 20 g of the surface-modified zirconia fine particles, and the mixture is stirred and mixed at 60 ° C. for 6 hours. As a result, a surface-modified zirconia fine particle dispersion was prepared.

After adding 10 g of dimethyl silicone having a viscosity of 10 cSt as a resin raw material to 50 g of this surface-modified zirconia fine particle dispersion and stirring and mixing, toluene was removed by vacuum drying to obtain a resin composite composition.
(Example 6)
Using the acetic acid-containing zirconia fine particle dispersion of Example 2, a surface-modified zirconia fine particle dispersion and a resin composite composition were produced in the same manner as in Example 5.

(Comparative Example 2)
Using the acetic acid-containing zirconia fine particle dispersion of Comparative Example 1, a surface-modified zirconia fine particle dispersion and a resin composite composition were produced in the same manner as in Example 5.

(Comparative Example 3)
A surface-modified zirconia fine particle dispersion and a resin composite composition were prepared in the same manner as in Example 5 except that the number of washings of the surface-modified zirconia fine particle cake was reduced to 1 to increase the ammonium acetate content.

(Comparative Example 4)
As Comparative Example 4, dimethyl silicone containing no zirconia fine particles was prepared.

  The average dispersed particle size, visible light transmittance, ammonium acetate content, and viscosity and heat resistance of the resin composite compositions of the surface-modified zirconia fine particle dispersions of Examples 5 and 6 and Comparative Examples 2 and 3 were measured. These results are shown in Table 1.

  The average dispersion particle diameter, visible light transmittance, ammonium acetate content, and viscosity and heat resistance of the resin composite composition of the surface-modified zirconia fine particle dispersion are as follows.

(1) Average dispersion particle diameter It measured similarly to the organic acid containing zirconia dispersion liquid.
(2) Visible light transmittance Using a spectrophotometer (V-570, manufactured by JASCO Corporation), the transmittance of visible light having an optical path length of 10 mm when air is 100% in the wavelength range of 350 nm to 800 nm. The lowest value of was measured.
(3) Ammonium acetate content With reference to the method described in Japanese Patent Application Laid-Open No. 2003-149221, measurement was performed by gas chromatography using a flame ionization detector.
(4) Resin composite composition viscosity Measured with a rotary viscometer.
(5) Heat resistance The resin composite composition was held at 150 ° C for 500 hours, and the change was visually confirmed.

According to these evaluation results, the surface-modified zirconia fine particle dispersions of Examples 5 and 6 have high transparency, good handling properties with reduced viscosity increase when used as resin composite compositions, and excellent heat resistance. A resin composite composition was obtained.
The surface-modified zirconia fine particle dispersion of Comparative Example 2 had a large dispersed particle size and poor transparency, and the viscosity of the resin composite composition was significantly increased. In Comparative Example 3, it was found that the resin composite composition was inferior in heat resistance.

Claims (3)

A surface-modified zirconia fine particle dispersion containing a surface-modified zirconia fine particle whose surface is modified by an organic surface modifier, a dispersion medium, and an organic acid compound,
The average dispersed particle diameter of the zirconia fine particles in the surface-modified zirconia fine particles is 1 nm or more and 20 nm or less,
The organic surface modifier is at least one selected from the group consisting of an alkoxysilane compound, a siloxane compound and a titanium coupling agent,
The organic acid compound is at least one of ammonium formate, ammonium acetate, ammonium propionate and ammonium butyrate,
The surface-modified zirconia fine particle dispersion, wherein the content of the organic acid compound is less than 3% by mass with respect to the mass of the zirconia fine particles. A resin composite composition comprising mixing the surface-modified zirconia fine particle dispersion according to claim 1 and a resin raw material, and then removing the solvent. A method for producing a surface-modified zirconia fine particle dispersion according to claim 1 , comprising the following steps.
(1) An organic acid, zirconia fine particles having an average dispersed particle diameter of 1 nm or more and 20 nm or less, and a dispersion medium containing at least water, and the organic acid is at least any of formic acid, acetic acid, propionic acid, and butyric acid The organic acid is an organic acid-containing zirconia fine particle dispersion that is 0.001 g or more and 0.05 g or less with respect to a surface area of 1 m ² of the zirconia fine particles,
A step of adding an organic surface modifier to the organic acid-containing zirconia fine particle dispersion and replacing the organic acid on the surface of the zirconia fine particles with the organic surface modifier.
(2) A step in which ammonia or an amine is added to the dispersion liquid after step (1) and the pH is adjusted to 7.5 or more to make the contained organic acid an organic acid compound.
(3) A step of subjecting the dispersion after step (2) to a solid-liquid separation treatment and washing the resulting surface-modified zirconia fine particle cake.
(4) A step of drying the surface-modified zirconia fine particle cake obtained in step (3) and then redispersing it in a dispersion medium.