JPWO2011013637A1 - Surface-modified zirconia nanocrystal particles and production method thereof, and silicone-based composite material and production method thereof - Google Patents

Abstract

Dispersion contribution to the dispersion medium consisting of a modification part for surface modification of zirconia nanoparticles, a stability contribution part composed of a carbon skeleton bonded to the modification part, and a polymer chain bonded to the stability contribution part The surface-modified zirconia nanocrystal particles are modified into a surface-modified zirconia nanocrystal particles in which the zirconia nanoparticles are modified by a compound having a part in one molecule, and a thermosetting silicone resin matrix obtained by crosslinking and curing. It is a silicone-based composite material that is dispersed.

Description

The present invention relates to surface-modified zirconia nanocrystal particles and a method for producing the same, and a silicone-based composite material obtained using the surface-modified zirconia nanocrystal particles and a method for producing the same.
More specifically, the present invention relates to surface-modified zirconia nanocrystal particles that can be stably dispersed in a thermosetting silicone resin matrix, an effective production method thereof, and the surface-modified zirconia nanoparticle in the thermosetting silicone resin matrix. The present invention relates to a silicone-based composite material that contains crystal particles with good dispersibility and is useful as an LED (light emitting diode) sealing material and the like, and an effective manufacturing method thereof.

  Conventionally, a thermosetting silicone resin used as an LED sealing material is excellent in heat resistance and weather resistance, but has a problem of low refractive index and low light extraction efficiency from an LED.

  In order to solve this, an attempt is made to improve the refractive index by preparing a composite of titania nanocrystal particles made lipophilic by surface modification and a thermosetting silicone resin (Patent Document 1).

  Properties required for nanocrystalline particles to make a composite with silicone resin include crystallinity of nanocrystalline particles themselves to ensure refractive index, high dispersibility in silicone resin matrix, dispersion in silicone resin matrix Stability and so on.

WO2008 / 075784 JP 2007-269601 A

Shuxue Zhou et al. , Langmuir 2007, 23, 9178-9187.

  The nanoparticle described in Patent Document 1 has an integrated structure because the coating portion covering the nanoparticle surface and the surface modifier for solvent dispersibility originate from the same raw material. Yes. Therefore, there is a problem that the range of selection of surface modifiers on the surface of titania nanocrystal particles is narrow when applied to various purposes. Also, when changing the surface modifier, it is necessary to review the synthesis method each time.

  Moreover, although the silicone composite of patent document 1 forms the coupling | bonding by the crosslinking reaction by condensation between the silicone resin and the surface modifier of the nanocrystal particle surface, it actually tries the method of patent document 1 The dispersion stability of the nanocrystal particles is low, the dispersibility in the silicone resin matrix is low, and the stability of the physical properties of the product is low, and the method of Patent Document 1 has many problems. It has been found.

  In addition, since titania nanocrystal particles exhibit a photochromism that is colored blue when irradiated with ultraviolet light, the visible light transmittance is significantly changed. For this reason, it turned out that the composite using a titania nanocrystal particle is unsuitable as a LED sealing material.

  Considering the above-mentioned problems in titania nanocrystal particles, zirconia nanocrystal particles can be substituted for titania nanocrystal particles as a high refractive index and high strength material.

  On the other hand, Non-Patent Document 1 describes a method for producing solvent-dispersible zirconia nanocrystal particles by synthesizing non-solvent zirconia nanocrystal particles and then surface-modifying the nanocrystal particle surface. .

  Specifically, non-dispersible zirconia nanocrystal particles obtained by the benzyl alcohol decomposition method developed by the authors of Non-Patent Document 1 were subjected to four types of surface modification having a vinyl group using tetrahydrofuran (THF) as a solvent. 3- (trimethoxysilyl) propyl methacrylate (MPS), ethyl 3,4-dihydroxycinnamate (EDHC), allylmalonic acid (AMA), trimethylolpropyne monoallyl ether (TMPMA) Non-patent document 1 describes that solvent-dispersible zirconia nanocrystal particles were obtained by optimizing the concentration.

  Further, this Non-Patent Document 1 is characterized by the decomposition method of benzyl alcohol, which is an anhydrous system, and is characterized in that the surface of the produced zirconia nanocrystal particles is covered with molecules derived from benzyl alcohol (normally The sol-gel method is covered with a hydroxyl group), which enables modification with a surface modifier.

  However, the benzyl alcohol decomposition method of Non-Patent Document 1 is problematic in that a large amount of benzyl alcohol having a boiling point close to 200 ° C. is used and the raw material zirconium alkoxide is expensive, and is not suitable for mass production. .

  Further, Non-Patent Document 1 reports that the concentration of zirconia nanocrystal particles in a THF solvent is as low as about 1% by mass, and that solvent dispersibility was obtained, but it was intended for mixing into a silicone resin matrix. It cannot be said that the nanocrystal particles have a sufficient function.

Although there is a report that a nanocrystal particle dispersion was obtained, the surface modifier was simply added, so even if only nanocrystal particles were isolated from the dispersion by centrifugation, etc. It is unlikely that a child remains on the nanocrystal particle surface. In fact, as a result of experiments conducted by the present inventors, it was not possible to disperse the isolated nanocrystal particles in the solvent again.
That is, in the zirconia nanocrystal particles of Non-Patent Document 1, stable solvent dispersibility is not ensured.

  Moreover, although it is a related technique, the manufacturing method of the metal oxide nanocrystal which can obtain a metal oxide nanocrystal with high crystallinity for a short time at low temperature is also known (patent document 2).

  In the technique of Patent Document 2, an oxygen-containing organic solvent is used as a reaction medium for a reaction in which the metal oxide precursor is converted into metal oxide nanocrystals, and as a solvent for supplying oxygen to the metal oxide precursor. I use it. Furthermore, it is also described that the metal oxide nanocrystals obtained are modified with carboxylic acids by adding carboxylic acids as an additive different from the oxygen-containing organic solvent.

  However, in Patent Document 2, a metal oxide nanocrystal is modified with an organic component to improve dispersibility of the metal oxide nanocrystal with respect to an organic compound. However, in this case as well, as in Non-Patent Document 1, only the surface modifier is added as an additive. Therefore, even if only nanocrystal particles are isolated from the dispersion by centrifugation, the surface modifier can be used. The possibility of remaining on the nanocrystal particle surface is low.

The present invention has been made under such circumstances, and a first object is to provide surface-modified zirconia nanocrystal particles that can be stably dispersed in a thermosetting silicone resin matrix and a method for producing the same. is there.
Furthermore, the second object is to provide a silicone-based composite material containing the surface-modified zirconia nanocrystal particles in a thermosetting silicone resin matrix with good dispersibility and a method for producing the same.

As a result of intensive research to achieve the above object, the present inventor has made a dispersive contribution to a dispersion medium such as an organosiloxane and a modification such as a carboxyl group of a carboxylic acid in one molecule. In addition, the inventors have found that a stable solvent dispersibility can be imparted by modifying the surface of the zirconia nanocrystal with a compound comprising a predetermined carbon skeleton and provided with a portion capable of imparting stability to the dispersibility.
More specifically, it has a polyorganosiloxane chain having a specific length that contributes mainly to an improvement in dispersibility in the thermosetting silicone resin matrix, and further, a regulator for the specific length of this polyorganosiloxane chain (ie, As a role for stabilizing the improved dispersibility, the inventors have conceived that the surface of the zirconia nanocrystal particles is modified with a compound having an aliphatic carboxylic acid residue having a specific carbon number. And it discovered that the above-mentioned purpose could be achieved by this surface modification zirconia nanocrystal particle.
Further, in the organic solvent, the above-mentioned object can also be achieved by subjecting the zirconia nanocrystal particles surface-modified with an arylsulfonic acid residue to a substitution treatment with the above-mentioned aliphatic carboxylic acid residue. I found out.
The present invention has been completed based on such findings.

That is, the present invention
(1) a modified portion for modifying the surface of the zirconia nanoparticles;
A stability-contributing part comprising a carbon skeleton bonded to the modifying part;
A dispersibility contributing part to a dispersion medium, comprising a polymer chain bonded to the stability contributing part,
A surface-modified zirconia nanocrystal particle, wherein the zirconia nanoparticle is modified with a compound provided in one molecule,
(2) The dispersibility contributing part is a polyorganosiloxane chain having 4 to 100 organosiloxane units,
A combination of the stability contributing part and the modifying part is a group derived from an aliphatic carboxylic acid, and an aliphatic carboxylic acid residue having 2 to 18 carbon atoms in the aliphatic group,
Surface-modified zirconia nanocrystal particles according to (1), wherein the surface-modified zirconia nanoparticles are modified with the aliphatic carboxylic acid residue,
(3) The surface-modified zirconia nanocrystal particles according to (2), wherein the aliphatic carboxylic acid is a linear saturated monocarboxylic acid,
(4) The surface-modified zirconia nanocrystal particles according to (2) or (3), wherein the polyorganosiloxane chain is a polydimethylsiloxane chain,
(5) The surface-modified zirconia nanocrystal particles according to any one of (1) to (4), wherein the dispersion medium is a thermosetting silicone resin matrix,
(6) a step of surface-modifying zirconia nanocrystal particles with an arylsulfonic acid residue that may have a substituent on the aromatic ring in an organic solvent;
A modification part for modifying the surface of the zirconia nanoparticles, a stability contribution part composed of a carbon skeleton bonded to the modification part, and a dispersibility contribution part composed of a polymer chain bonded to the stable dispersion contribution part Substituting the arylsulfonic acid residue with a compound provided in one molecule;
A method for producing surface-modified zirconia nanocrystal particles, comprising:
(7) The method for producing surface-modified zirconia nanocrystal particles according to (6), wherein the aryl sulfonic acid is p-toluenesulfonic acid,
(8) A silicone-based composite in which the surface-modified zirconia nanocrystal particles according to any one of (1) to (5) are dispersed in a thermosetting silicone resin matrix obtained by crosslinking and curing. material,
(9) The silicone composite material according to (8), wherein the content of the surface-decorated zirconia nanocrystal particles is 5 to 80% by mass as ZrO2, and
(10) A liquid mixture containing (a) a thermosetting silicone resin, an organic solvent dispersion of the surface-modified zirconia nanocrystal particles according to any one of (1) to (5), and a curing catalyst is prepared. And a process of
(B) distilling off the solvent in the mixed solution;
(C) heat-treating the mixture after the solvent is distilled off, and crosslinking and curing the thermosetting silicone resin;
The manufacturing method of the silicone type composite material characterized by including this is provided.

In the present specification, the silicone resin before crosslinking and curing is referred to as “thermosetting silicone resin”, and the silicone resin after crosslinking and curing is referred to as “thermosetting silicone resin”.
In the present specification, a group derived from an aliphatic carboxylic acid and chemically bonded to the zirconia nanocrystal surface (for example, “carboxyl group in aliphatic carboxylic acid”, “aliphatic carboxyoxy group”, etc.) It is called “aliphatic carboxylic acid residue”. Similarly, a group derived from aryl sulfonic acid and chemically bonded to the zirconia nanocrystal surface (for example, “sulfone group in aryl sulfonic acid”, “aryl sulfonyloxy group”, etc.) is converted to “aryl sulfonic acid residue”. It is called. The “arylsulfonic acid residue” includes those having a substituent on the aromatic ring and those having no substituent on the aromatic ring.

  According to the present invention, surface-modified zirconia nanocrystal particles that can be stably dispersed in a thermosetting silicone resin matrix, a method for producing the same, and the surface-modified zirconia nanocrystal particles in the thermosetting silicone resin matrix have good dispersibility. A silicone-based composite material containing the same and a method for producing the same can be provided.

Embodiments according to the present invention will be described below.
As an order, in <Embodiment 1>, surface-modified zirconia nanocrystal particles and a manufacturing method thereof will be described.
In <Embodiment 2>, a silicone-based composite material containing surface-modified zirconia nanocrystal particles and a manufacturing method thereof will be described.
Furthermore, for <Embodiment 3>, various modifications will be described.

<Embodiment 1>
First, in the present embodiment, the surface-modified zirconia nanocrystal particles manufactured by this method will be described while describing the manufacturing method.

[Modification of zirconia nanocrystal particles with organic sulfonic acid]
First, in a suitable organic solvent A, a zirconia precursor is reacted with an organic sulfonic acid, preferably an aryl sulfonic acid such as benzene sulfonic acid or p-toluene sulfonic acid, particularly preferably p-toluene sulfonic acid, Arylsulfonic acid residue-modified zirconia nanocrystal particles, particularly preferably p-toluenesulfonic acid residue (sometimes abbreviated as PTSH) modified zirconia nanocrystal particles are formed.

Zirconyl chloride, tetraalkoxyzirconium, and the like can be used as the zirconia precursor used in this case, but zirconyl chloride is preferable from the viewpoint of reactivity, and zirconyl chloride octahydrate (ZrOCl ₂ .8H ₂ O) is particularly preferable. Is preferred.

  When p-toluenesulfonic acid is used as the arylsulfonic acid, the molar ratio of Zr to p-toluenesulfonic acid in the zirconia precursor is preferably 8: 1 to 1: 2. If the proportion of p-toluenesulfonic acid is less than the above range, the dispersibility of the PTSH-modified zirconia nanocrystal particles may be lowered. A more preferred molar ratio of Zr to p-toluenesulfonic acid is in the range of 4: 1 to 1: 1.

  The organic solvent A is not particularly limited as long as PTSH-modified zirconia nanocrystal particles are effectively formed. For example, a mixed solvent of ethanol and triethyl orthoformate can be preferably used.

  The organic solvent A is a mixed solvent of ethanol and triethyl orthoformate, the zirconia precursor is the zirconyl chloride octahydrate, and the aryl sulfonic acid is the p-toluene. When using each of sulfonic acids, the reaction is preferably carried out in a pressurized vessel at a temperature of 100 to 240 ° C, more preferably 120 to 200 ° C.

  This reaction time depends on the reaction temperature, the amount of p-toluenesulfonic acid, and the like, and cannot be generally determined, but is usually about 8 to 120 hours, preferably 12 to 60 hours.

In addition, the crystal structure of the zirconia nanocrystal produced | generated by reaction time can be selected. That is, the optimal reaction time varies depending on the raw material concentration, the molar ratio of the zirconia precursor to the sulfonic acid, and the reaction temperature, but when the reaction temperature is shortened, tetragonal zirconia nanocrystals are formed, and when the reaction temperature is increased, monoclinic zirconia nanocrystals are formed. Tend to generate.
Tetragonal zirconia nanocrystals have a higher refractive index than monoclinic zirconia nanocrystals, and monoclinic zirconia nanocrystals appear to be chemically more stable than tetragonal zirconia nanocrystals. Each can be made according to the intended use.

  After completion of the reaction, the solvent in the reaction solution is preferably distilled off under reduced pressure to obtain PTSH-modified zirconia nanocrystal particles having a structure represented by the following formula (1).

  The PTSH-modified zirconia nanocrystal particles are obtained as a white powder and can be redispersed in an organic solvent such as methanol or methylene chloride, thereby obtaining a colorless and transparent zirconia nanocrystal particle dispersion.

[Modification of the zirconia nanocrystal particles with the compound of this embodiment]
Next, with respect to the PTSH-modified zirconia nanocrystal particles obtained in this way, a modified part for modifying the surface of the zirconia nanoparticles, a stability contributing part comprising a carbon skeleton bonded to the modified part, and a dispersion medium Modification is performed with a compound having a dispersibility contribution portion composed of a polymer chain bonded to the stability contribution portion and in one molecule.

  Specifically, the dispersibility contributing part is a polyorganosiloxane chain having 4 to 100 organosiloxane units, and the combination of the stability contributing part and the modifying part is an aliphatic carboxylic acid. A zirconia nanocrystal particle obtained by modifying a surface of a zirconia nanoparticle with an aliphatic carboxylic acid residue having 2 to 18 carbon atoms in the aliphatic group, Let it form.

The polyorganosiloxane chain preferably has 4 to 100 organosiloxane units.
When the organosiloxane unit of the polyorganosiloxane chain is smaller than 4, the dispersibility of the zirconia nanocrystal particles in the silicone resin matrix decreases.
On the other hand, when the organosiloxane chain unit is larger than 100, the formation of zirconia nanocrystal particles modified with the aliphatic carboxylic acid residue is remarkably slowed. The reason is presumed to be due to steric hindrance of the polyorganosiloxane chain.

  The polyorganosiloxane chain is preferably a polydimethylsiloxane (hereinafter sometimes abbreviated as PDMS) chain.

On the other hand, as the aliphatic carboxylic acid, the aliphatic group preferably has 2 to 18 carbon atoms, and is preferably a linear saturated monocarboxylic acid.
If the number of carbon atoms in the aliphatic group is less than 2, the aliphatic carboxylic acid becomes unstable and decomposes during the reaction.
If the aliphatic group has more than 18 carbon atoms, the volume occupied by the aliphatic group becomes extremely large, which makes it meaningless to improve the refractive index.
In addition, the methylene chain has a small contribution to the dispersibility in silicone, so it should be as short as possible.

  The COOH group in the aliphatic carboxylic acid having a polyorganosiloxane chain may be present at the terminal of the polyorganosiloxane chain or may be present at the side chain, but may be present at the terminal. preferable.

The aliphatic carboxylic acid having a polyorganosiloxane chain as a surface modification may be abbreviated as POS-COOH, and the aliphatic carboxylic acid having a polydimethylsiloxane chain may be abbreviated as PDMS-COOH.
As described above, in this embodiment, as a surface modifier, an aliphatic carboxylic acid (PDMS-COOH) residue having a polydimethylsiloxane chain (hereinafter referred to as “PDMS-COOH residue”) may be abbreviated. ) Is preferred.

  In the present embodiment, in order to obtain the zirconia nanocrystal particles modified with the PDMS-COOH residue, the PTSH-modified zirconia nanocrystal particles obtained as described above are redispersed in an appropriate organic solvent B, A method is adopted in which the above PDMS-COOH is added, sodium carbonate is further added, and the mixture is stirred overnight at room temperature.

  The organic solvent B is not particularly limited, but for example, a mixed solvent of methanol and methylene chloride is preferably used. For example, the following operation is performed on the reaction solution after completion of the reaction.

  After distilling off the solvent in the reaction solution, excess methanol is added, subjected to solid-liquid separation means such as centrifugation, the resulting precipitate is redispersed in a solvent such as toluene, and the same methanol as above Repeat the wash several times. Next, the toluene dispersion is filtered to remove sodium carbonate, whereby zirconia nanocrystal particles modified with a PDMS-COOH residue (ie, PDMS-COO group) having a structure represented by the following formula (2) Can be obtained.

(In the formula, n represents the number of dimethylsiloxane units, and m represents the carbon number of the aliphatic group in the aliphatic carboxylic acid residue.)

[Effect of this embodiment]
According to this embodiment, not only a dispersibility-contributing part to a dispersion medium, such as organosiloxane, or a modified part such as a carboxyl group of carboxylic acid, but also a predetermined carbon skeleton in one molecule Stable solvent dispersibility can be imparted by modifying the surface of the zirconia nanocrystal with a compound provided with a portion capable of imparting stability to dispersibility.

<Embodiment 2>
Next, a silicone-based composite material containing the surface-modified zirconia nanocrystal particles in Embodiment 1 will be described.

  The silicone-based composite material of the present embodiment is a dispersion medium that is a zirconia nanoparticle that is surface-modified with a POS-COOH residue, preferably a PDMS-COOH residue, in a thermosetting silicone resin matrix that is crosslinked and cured. It is characterized in that crystal grains are dispersed.

  Since the zirconia nanocrystal particles surface-modified with the POS-COOH residue, preferably PDMS-COOH residue, have a siloxane unit in the qualifier, they are crosslinked in a thermosetting silicone resin (that is, dispersed). In the medium) very well and stably dispersed.

In the silicone-based composite material of the present embodiment, the content of the surface-modified zirconia nanocrystal particles is preferably 5 to 80% by mass as ZrO ₂ from the viewpoint of improving the refractive index and dispersibility, and 10 to 50% by mass. More preferred.
When the content of the nanocrystal particles is less than 5% by mass, there is little meaning in improving the refractive index.
On the other hand, if the content of the nanocrystal particles exceeds 80%, the possibility of devitrification due to the aggregation of the particles increases, and the properties of the resin are impaired, such as being extremely brittle even if transparent.
From the viewpoint of achieving both improved refractive index and dispersibility in the silicone resin matrix, the content of the surface-modified zirconia nanocrystal particles is more preferably 10 to 50% by mass as ZrO ₂ .

  The silicone composite material can be efficiently produced according to the method of the present embodiment shown below.

The method for producing the silicone-based composite material of the present invention includes:
(A) A liquid mixture comprising a thermosetting silicone resin, an organic solvent dispersion of zirconia nanocrystal particles surface-modified with the POS-COOH residue, preferably PDMS-COOH residue, and a curing catalyst is prepared. And a process of
(B) distilling off the solvent in the mixed solution;
(C) heat-treating the mixture after the solvent is distilled off, and crosslinking and curing the thermosetting silicone resin.

As the thermosetting silicone resin used in the step (a), a mixture of an addition reaction type silicone resin and a silicone-based crosslinking agent can be used. Examples of the addition reaction type silicone resin include at least one selected from polyorganosiloxanes having an alkenyl group as a functional group in the molecule.
Preferred examples of the polyorganosiloxane having an alkenyl group as a functional group in the molecule include polydimethylsiloxane having a vinyl group as a functional group, polydimethylsiloxane having a hexenyl group as a functional group, and a mixture thereof. .

  Examples of the silicone-based crosslinking agent include polyorganosiloxane having at least two silicon-bonded hydrogen atoms in one molecule, specifically, a dimethylhydrogensiloxy group end-capped dimethylsiloxane-methylhydrogensiloxane copolymer, Examples thereof include trimethylsiloxy group-end-capped dimethylsiloxane-methylhydrogensiloxane copolymer, trimethylsiloxane group-end-capped poly (methylhydrogensiloxane), and poly (hydrogensilsesquioxane).

  Further, as the curing catalyst, a platinum compound is usually used. Examples of the platinum compound include fine platinum, fine platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, palladium, rhodium catalyst, and the like. .

In this embodiment, a colorless and transparent zirconia nanocrystal particle-containing silicone resin dispersion with high viscosity is obtained by the steps (a) and (b).
Next, in step (c), the silicone resin dispersion is subjected to heat treatment at a temperature of, for example, 100 to 200 ° C. for about 1 to 12 hours to crosslink and cure the thermosetting silicone resin. A composite material is obtained.

  The silicone-based composite material thus obtained is transparent, and the refractive index depends on the content of zirconia nanocrystal particles, but is usually about 1.4 to 1.6.

  According to this embodiment, surface-modified zirconia nanocrystal particles that can stably maintain good dispersibility with respect to the dispersion medium can be included in the thermosetting silicone resin matrix with good dispersibility.

<Embodiment 3>
The technical scope of the present invention is not limited to the above-described embodiments, and includes various modifications and improvements as long as the specific effects obtained by the constituent elements of the invention and combinations thereof can be derived.
Therefore, in this embodiment, various modifications in Embodiment 1 are shown. The points not particularly noted are the same as in the first embodiment.

In Embodiment 1, a compound having a modifying part, a stability contributing part, and a dispersibility contributing part in one structural formula is given. As a specific example thereof, a fat having both a modifying part and a stability contributing part The group carboxylic acid residue was mentioned.
On the other hand, if the zirconia nanoparticles can be modified, it may not be an aliphatic carboxylic acid residue. For example, a ketone group or an aldehyde group may be applicable.
In addition, with respect to the stability-contributing portion composed of a carbon skeleton, a predetermined number of carbon chains may be bonded to these modifying portions.

  Furthermore, as for the dispersibility contributing part, other than the polyorganosiloxane chain may be used as long as the surface-modified zirconia nanoparticles can be dispersed well. In this case, the adjustment for stabilizing the dispersibility may be performed by changing the number of carbon atoms in the stability contributing portion or by providing a substituent on the carbon skeleton.

  In addition, for the modifying part, the stability contributing part, and the dispersibility contributing part, the functional group in each part can be used as long as each function can be exhibited even if other functional groups or carbon chains are bonded. Those containing other functional groups, carbon chains and the like described in the above are referred to as a modifying part, a stability contributing part, and a dispersibility contributing part.

On the other hand, not the zirconia nanoparticles modified with an aliphatic carboxylic acid residue but a stage before this modification, that is, a stage modified with an aryl sulfonic acid residue will be described.
In Embodiment 1, the arylsulfonic acid residue is described. However, the arylsulfonic acid residue is not limited to the arylsulfonic acid residue as long as it can be substituted later with the above-described compound. For example, organic sulfonic acids other than aryl sulfonic acids may be used, and even those having a ketone group or an aldehyde group may be applicable.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

<Example 1>
[1. Production of PTSH-modified zirconia nanocrystal particles]
Oxide chloride, zirconium octahydrate (ZrOCl ₂ · _{8H 2} O, manufactured by Kanto Kagaku) 1.29 g and (4 mmol) p-toluenesulfonic acid monohydrate (manufactured by Kanto Chemical) 190 mg (1 mmol), ethanol (Wako Pure It was dissolved in a mixed solvent of 20 ml of Yakuhin Kogyo) and 5 ml of triethyl orthoformate (manufactured by Kanto Chemical).

  This solution was filled in a pressurized container (made of stainless steel with a 50 ml Teflon (registered trademark) inner cylinder), heated in an oven at 170 ° C. for 40 hours, allowed to cool to room temperature, and then the pressurized container was released. At this time, the reaction solution was colorless and transparent, and no precipitation was observed.

  After removing the solvent from the reaction solution with an evaporator under reduced pressure, 670 mg of white powder of zirconia nanocrystals was obtained. When 3 ml of methanol (manufactured by Kanto Chemical Co., Ltd.) and 3 ml of methylene chloride (manufactured by Wako Pure Chemical Industries, Ltd.) are added thereto, a uniform and redispersible and colorless and transparent zirconia nanoparticle dispersion solution is obtained.

As a result of analyzing the white powder by powder X-ray diffraction (XRD), it was confirmed that the crystal form was a tetragonal zirconium oxide crystal. Moreover, as a result of observation by infrared spectroscopy (IR), it was confirmed that the PTSH surface-modified zirconia nanocrystal particles, which are the white powder, were chemically bonded to the surface of the zirconia nanoparticles.
Moreover, as a result of observation with a transmission electron microscope (TEM), it was confirmed that the crystal was a microcrystal having a diameter of 2 to 3 nm. Moreover, when the composition ratio of the product was measured by elemental analysis using inductively coupled plasma atomic emission (ICP-AES), it was Zr / S = 4.06 [mol ratio].

[2. Surface modifier substitution of PTSH-modified zirconia nanocrystal particles]
The PTSH-modified zirconia nanocrystal particles obtained in the above step were redispersed in a mixed solvent of methanol and methylene chloride in a volume ratio of 10: 3. At this time, re-dispersion was performed so that the solvent was about 10 ml per 4 mmol of Zr. As a result, a colorless and transparent zirconia nanoparticle dispersion solution was obtained.

  To 10 ml of this re-dispersed liquid, 1 mmol of carboxylic acid having a polydimethylsiloxane chain having an average number of polydimethylsiloxane units of 12 and 0.55 mmol of sodium carbonate are added and stirred overnight at room temperature to obtain a cloudy reaction liquid. It was. In addition, as this carboxylic acid, the molecule | numerator for surface modification which forms Formula (2), Comprising: The average of n and the molecule | numerator of m = 10 were used (made by Polymer Source).

  Subsequently, after this reaction liquid was applied to an evaporator, methanol was added in excess, and centrifugation was performed to collect a precipitate. It was confirmed that the precipitate was well dispersed in toluene. The same methanol washing was repeated several times.

  When the obtained toluene dispersion is filtered to remove sodium carbonate, a zirconia nanocrystal particle dispersion in which p-toluenesulfonic acid is substituted and surface-modified with a PDMS-COOH residue (ie, PDMS-COO group) is obtained. It was. When the composition ratio of Zr / S was measured by elemental analysis using ICP-AES, it was Zr / S = 4.06 [mol ratio] as described above before the substitution, whereas Zr / S after the substitution. = 431 [mol ratio], and sulfur was almost lost with respect to Zr.

As described above, since sulfur has almost disappeared, it was confirmed that the surface modifier on the surface of the zirconia nanocrystal particles was substituted from PTSH to the PDMS-COOH residue.
Moreover, it was confirmed by IR measurement that the PDMS-COOH residue surface-modified the nanocrystal particle surface. Furthermore, XRD and TEM observation confirmed that the zirconia nanocrystal portion was not changed from the nanocrystal obtained in Example 1. That is, it was confirmed that the crystal form was a tetragonal zirconium oxide crystal and a microcrystal having a diameter of 2 to 3 nm.

<Example 2>
Zirconia nanocrystals surface-modified with PDMS-COO-group obtained in the above (1) to 2 g of “SS-6001” (thermosetting silicone resin) A and B mixed by equal amounts from San Yulec Co. 1 g of the toluene dispersion of particles was added as ZrO _{2 and} stirred well to prepare a mixed solution.

Subsequently, the solvent in this liquid mixture was distilled off by an evaporator to obtain a colorless and transparent ZrO ₂ nanocrystal particle-containing silicone resin dispersion having a relatively high viscosity.

Next, this silicone resin dispersion was cured by heating in an oven at 160 ° C. for 12 hours to obtain a transparent ZrO ₂ / silicone composite material.

The ZrO ₂ content in the composite material was 50% by mass, and the refractive index of the composite material was 1.51. The refractive index of the silicone resin produced without adding zirconia nanocrystals was 1.41, indicating that mixing with zirconia nanocrystals is effective in improving the resin refractive index.

  The surface-modified zirconia nanocrystal particles of the present invention can be stably dispersed in a thermosetting silicone resin matrix, and can provide a silicone-based composite material useful as an LED sealing material or the like.

Claims (10)

A modification for surface modification of zirconia nanoparticles;
A stability-contributing part comprising a carbon skeleton bonded to the modifying part;
A dispersibility contributing part to a dispersion medium, comprising a polymer chain bonded to the stability contributing part;
The surface-modified zirconia nanocrystal particles, wherein the zirconia nanoparticles are modified with a compound provided in one molecule. The dispersibility contributing part is a polyorganosiloxane chain having 4 to 100 organosiloxane units,
A combination of the stability contributing part and the modifying part is a group derived from an aliphatic carboxylic acid, and an aliphatic carboxylic acid residue having 2 to 18 carbon atoms in the aliphatic group,
The surface-modified zirconia nanocrystal particles according to claim 1, wherein the surface-modified zirconia nanoparticles are modified with the aliphatic carboxylic acid residue.   The surface-modified zirconia nanocrystal particles according to claim 2, wherein the aliphatic carboxylic acid is a linear saturated monocarboxylic acid.   The surface-modified zirconia nanocrystal particle according to claim 2 or 3, wherein the polyorganosiloxane chain is a polydimethylsiloxane chain.   The surface-modified zirconia nanocrystal particles according to any one of claims 1 to 4, wherein the dispersion medium is a thermosetting silicone resin matrix. Surface-modifying zirconia nanocrystal particles with an aryl sulfonic acid residue which may have a substituent on an aromatic ring in an organic solvent;
A modification part for modifying the surface of the zirconia nanoparticles, a stability contribution part composed of a carbon skeleton bonded to the modification part, and a dispersibility contribution part composed of a polymer chain bonded to the stable dispersion contribution part Substituting the arylsulfonic acid residue with a compound provided in the molecule;
A method for producing surface-modified zirconia nanocrystal particles, comprising:   The method for producing surface-modified zirconia nanocrystal particles according to claim 6, wherein the arylsulfonic acid is p-toluenesulfonic acid.   A silicone-based composite material in which the surface-modified zirconia nanocrystal particles according to any one of claims 1 to 5 are dispersed in a thermosetting silicone resin matrix obtained by crosslinking and curing. The silicone composite material according to claim 8, wherein the content of the surface-decorated zirconia nanocrystal particles is 5 to 80% by mass as ZrO ₂ . (A) preparing a liquid mixture comprising a thermosetting silicone resin, an organic solvent dispersion of the surface-modified zirconia nanocrystal particles according to any one of claims 1 to 5, and a curing catalyst;
(B) distilling off the solvent in the mixed solution;
(C) heat-treating the mixture after the solvent is distilled off, and crosslinking and curing the thermosetting silicone resin;
The manufacturing method of the silicone type composite material characterized by including this.