WO2011013637A1

WO2011013637A1 - Surface-modified zirconia nanocrystal particles and method for producing same, and silicone composite material and method for producing same

Info

Publication number: WO2011013637A1
Application number: PCT/JP2010/062566
Authority: WO
Inventors: 秀造徳光
Original assignee: Hoya株式会社
Priority date: 2009-07-28
Filing date: 2010-07-27
Publication date: 2011-02-03
Also published as: JPWO2011013637A1

Abstract

Disclosed are surface-modified zirconia nanocrystal particles which are obtained by surface-modifying zirconia nanoparticles with a compound that comprises, in each molecule, a modifying moiety for surface-modifying a zirconia nanoparticle, a stability-providing moiety that is composed of a carbon skeleton bound to the modifying moiety, and a dispersibility-providing moiety that is composed of a polymer chain bound to the stability-providing moiety and provides the dispersion medium with dispersibility. Also disclosed is a silicone composite material which is obtained by dispersing the surface-modified zirconia nanocrystal particles in a thermoset silicone resin matrix that is cured by crosslinking.

Description

Surface-modified zirconia nanocrystal particles and method for producing the same, and silicone based composite material and method for producing the same

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 particularly, the present invention relates to surface-modified zirconia nanocrystal particles stably dispersible in a thermosetting silicone resin matrix, an effective method for producing the same, and the surface-modified zirconia nano particles in the thermosetting silicone resin matrix. The present invention relates to a silicone-based composite material useful as an LED (light emitting diode) sealing material or the like, which contains crystal particles with high dispersibility, 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 that the refractive index is low and the light extraction efficiency from the LED is low.

In order to solve this, it aims at refractive index improvement by producing the composite of the titania nanocrystal particle made lipophilic by surface modification, and a thermosetting silicone resin (patent document 1).

Properties necessary for nanocrystalline particles for producing a composite with silicone resin include crystallinity of nanocrystalline particles themselves for securing refractive index, high dispersibility in silicone resin matrix, and dispersion in silicone resin matrix Stability etc. are mentioned.

WO 2008/075784 JP 2007-269601A

The nanoparticles described in the patent document 1 have an integrated structure because the coating portion for coating the surface of the nanoparticles and the surface modifier for solvent dispersibility are derived from the same raw material. There is. Therefore, when it is intended to apply to various purposes, there is a problem that the range of selection of surface modifiers on the surface of titania nanocrystalline particles is narrow. In addition, when changing the surface modifier, it is necessary to review the synthesis method each time.

Moreover, although the silicone composite described in Patent Document 1 forms a bond by a crosslinking reaction due to condensation between the silicone resin and the surface modifier of the surface of the nanocrystal particle, the method of Patent Document 1 is tried in practice. In addition, the dispersion stability of the nanocrystal particles is low, the dispersion in the silicone resin matrix is low, and furthermore, 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 the titania nanocrystalline particles exhibit photochromism that is colored in blue upon irradiation with ultraviolet light, the visible light transmittance is significantly changed. Therefore, it was found that a composite using titania nanocrystalline particles is unsuitable as an LED encapsulant.

Given the above problems with titania nanocrystalline particles, zirconia nanocrystalline particles can be substituted for titania nanocrystalline particles as high refractive index, high strength materials.

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

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

In addition, this non-patent document 1 is characterized by the benzyl alcohol decomposition method which is an anhydrous system, and the surface of the produced zirconia nanocrystal particles is characterized by being covered with molecules derived from benzyl alcohol (generally The sol-gel method is covered with hydroxyl groups, which allows modification by surface modifiers.

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

Furthermore, although Non-Patent Document 1 reports that the concentration of zirconia nanocrystal particles in THF solvent is very low, about 1 mass%, and that the solvent dispersibility is obtained, it was intended for mixing into a silicone resin matrix. The nanocrystal particles can not be said to have sufficient functions.

In addition, although there is a report that a nanocrystal particle dispersion has been obtained, the surface modification is only added, so even if only nanocrystal particles are isolated from the dispersion by centrifugation etc. It is unlikely that the particles remain on the surface of the nanocrystalline particle. In fact, as a result of experiments conducted by the present inventors, it was not possible to disperse the isolated nanocrystal particles even if they were to be dispersed again in the solvent.
That is, in the zirconia nanocrystal particle of Non-Patent Document 1, stable solvent dispersibility is not ensured.

Moreover, although it is related technology, the manufacturing method of the metal oxide nanocrystal which can obtain a metal oxide nanocrystal with high crystallinity in low temperature and a short time 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 the reaction in which the metal oxide precursor is converted to metal oxide nanocrystals, and as a solvent for supplying oxygen to the metal oxide precursor. I use it. Furthermore, modifying the obtained metal oxide nanocrystal with carboxylic acids is also described by adding carboxylic acids as an additive different from the oxygen-containing organic solvent.

However, in Patent Document 2, metal oxide nanocrystals are modified with an organic component to improve the dispersibility of metal oxide nanocrystals in an organic compound. However, also in this case, as in Non-Patent Document 1, since only the surface modifier is added as an additive, even if only nanocrystal particles are isolated from the dispersion by centrifugation etc. The possibility of remaining on the surface of nanocrystalline particles is low.

The present invention has been made under such circumstances, and a first object of the present invention 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.
A second object of the present invention is to provide a silicone-based composite material including the surface-modified zirconia nanocrystal particles well dispersed in a thermosetting silicone resin matrix, and a method for producing the same.

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

That is, the present invention
(1) a modification for surface modification of zirconia nanoparticles;
A stability contribution consisting of a carbon skeleton bound to said modification;
A dispersive contribution to a dispersion medium consisting of a polymer chain coupled to the stability contributing part;
A surface-modified zirconia nanocrystal particle, wherein the zirconia nanoparticle is modified by a compound provided in one molecule,
(2) The dispersion contributing portion is a polyorganosiloxane chain having 4 to 100 organosiloxane units,
A combination of the stability contributing portion and the modifying portion is a group derived from an aliphatic carboxylic acid, and is an aliphatic carboxylic acid residue having 2 to 18 carbon atoms in the aliphatic group,
The surface-modified zirconia nanocrystal particle according to (1), which is obtained by surface-modifying a zirconia nanoparticle with the aliphatic carboxylic acid residue.
(3) The surface-modified zirconia nanocrystal particle according to (2), wherein the aliphatic carboxylic acid is a linear saturated monocarboxylic acid.
(4) The surface-modified zirconia nanocrystal particle according to (2) or (3), wherein the polyorganosiloxane chain is a polydimethylsiloxane chain,
(5) The surface-modified zirconia nanocrystal particle according to any one of (1) to (4), wherein the dispersion medium is a thermosetting silicone resin matrix.
(6) surface-modifying zirconia nanocrystal particles with an arylsulfonic acid residue which may have a substituent on an aromatic ring in an organic solvent;
A modification for surface modification of zirconia nanoparticles, a stability contributing part comprising a carbon skeleton binding to the modifying part, and a dispersion contributing part comprising a polymer chain binding to the stable dispersion contributing part Replacing the aryl sulfonic acid residue with a compound provided in one molecule;
A method of producing surface-modified zirconia nanocrystals particles comprising
(7) The method for producing surface-modified zirconia nanocrystal particles according to (6), wherein the aryl sulfonic acid is p-toluene sulfonic acid,
(8) A silicone-based composite characterized in that the surface-modified zirconia nanocrystal particles according to any one of (1) to (5) are dispersed in a thermosetting silicone resin matrix formed by crosslinking and curing. material,
(9) The silicone-based composite material according to (8), wherein the content of the surface-modified zirconia nanocrystal particles is 5 to 80% by mass as ZrO 2, and
(10) (a) Preparation of a mixed liquid containing 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 The process to
(B) distilling off the solvent in the liquid mixture;
(C) heat treating the mixture after evaporation of the solvent to crosslink and cure the thermosetting silicone resin;
And providing a method of producing a silicone-based composite material.

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".
Further, in the present specification, a group derived from an aliphatic carboxylic acid and chemically bonded to the surface of the zirconia nanocrystal (eg, “a carboxyl group in an aliphatic carboxylic acid”, “aliphatic carboxy group”, etc.) It is called "aliphatic carboxylic acid residue". Similarly, a group derived from aryl sulfonic acid and chemically bonded to the surface of zirconia nanocrystal (eg, "sulfone group in aryl sulfonic acid", "arylsulfonyloxy group", etc.), "aryl sulfonic acid residue" It is called. The “aryl sulfonic 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 stably dispersible 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 with good dispersibility It is possible to provide a silicone based composite material containing the same and a method for producing the same.

Hereinafter, embodiments according to the present invention will be described.
As order, in <Embodiment 1>, surface modified zirconia nanocrystal particles and a method for producing the same will be described.
Then, in <Embodiment 2>, a silicone-based composite material including surface modified zirconia nanocrystal particles and a method for producing the same will be described.
Furthermore, <Modification 3> will be described with respect to various modified examples.

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 by organic sulfonic acid]
First, in an appropriate organic solvent A, a zirconia precursor is reacted with an organic sulfonic acid, preferably an arylsulfonic acid such as benzenesulfonic acid or p-toluenesulfonic acid, particularly preferably p-toluenesulfonic acid, Aryl sulfonic acid residue modified zirconia nanocrystal particles, particularly preferably p-toluene sulfonic acid residue (sometimes abbreviated as PTSH) modified zirconia nanocrystal particles are formed.

As the zirconia precursor used at this time, zirconyl chloride, tetraalkoxyzirconium and the like can be used, but zirconyl chloride is preferable from the viewpoint of reactivity, and zirconyl chloride octahydrate (ZrOCl ₂ · 8H ₂ O) is particularly preferable. It is suitable.

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 reduced. A more preferable 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 it can effectively form PTSH modified zirconia nanocrystal particles, and for example, a mixed solvent of ethanol and triethyl orthoformate can be preferably used.

Moreover, as the above-mentioned organic solvent A, a mixed solvent of the above-mentioned ethanol and triethyl orthoformate, as the above-mentioned zirconia precursor, the above-mentioned zirconyl chloride octahydrate, and as the above-mentioned arylsulfonic acid, the above-mentioned p-toluene When each sulfonic acid is used, the reaction is carried out in a pressure vessel, preferably at a temperature of 100 to 240 ° C., more preferably 120 to 200 ° C.

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

Note that the crystal structure of zirconia nanocrystals can be selected depending on the reaction time. That is, although the optimum reaction time changes depending on the raw material concentration, the molar ratio of the zirconia precursor and the sulfonic acid, and the reaction temperature, shortening the reaction temperature produces tetragonal zirconia nanocrystals, and lengthening the monoclinic zirconia nanocrystals It tends to generate.
Tetragonal zirconia nanocrystals have a higher refractive index than monoclinic zirconia nanocrystals, and monoclinic zirconia nanocrystals appear to be more chemically stable than tetragonal zirconia nanocrystals. It is possible to make each separately according to a use application.

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, can be redispersed in an organic solvent such as methanol or methylene chloride, and a colorless and transparent zirconia nanocrystal particle dispersion can be obtained.

[Modification of zirconia nanocrystal particles by the compound of this embodiment]
Next, to the thus-obtained PTSH-modified zirconia nanocrystal particle, a modified portion for modifying the surface of the zirconia nanoparticle, a stability contributing portion comprising a carbon skeleton bonded to the modified portion, and a dispersion medium The compound is modified with a compound having, in one molecule thereof, a dispersiveness contributing portion, and a dispersiveness contributing portion consisting of a polymer chain that is bonded to the stability contributing portion.

Specifically, the dispersion contributing portion is a polyorganosiloxane chain having 4 to 100 organosiloxane units, and the combination of the stability contributing portion and the modifying portion is an aliphatic carboxylic acid. A group derived from an aliphatic carboxylic acid residue having 2 to 18 carbon atoms in the aliphatic group, and surface-modified zirconia nanoparticles by the aliphatic carboxylic acid residue; 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 is reduced.
On the other hand, when the organosiloxane chain unit is more than 100, the formation of the zirconia nanocrystal particles modified with the aliphatic carboxylic acid residue is significantly delayed. The reason is speculated to be due to steric hindrance of the polyorganosiloxane chain.

As the polyorganosiloxane chain, a polydimethylsiloxane (hereinafter sometimes abbreviated as PDMS) chain is preferable.

On the other hand, as the aliphatic carboxylic acid, the carbon number of the aliphatic group is preferably 2 to 18, and a linear saturated monocarboxylic acid is preferable.
When the carbon number of the aliphatic group is less than 2, the aliphatic carboxylic acid becomes unstable and is decomposed during the reaction.
If the carbon number of the aliphatic group is more than 18, the volume occupied by the aliphatic group becomes extremely large, and the meaning of the improvement of the refractive index is lost.
In addition, since the methylene chain has a small contribution to the dispersibility in silicone, it is better to be as short as possible.

The COOH group in the aliphatic carboxylic acid having a polyorganosiloxane chain may be present at the end of the polyorganosiloxane chain or may be present in the side chain, but it is required to be present at the end preferable.

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

In this 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 re-dispersed in a suitable organic solvent B, The above PDMS-COOH is added to this, sodium carbonate is further added, and it is possible to stir at room temperature overnight.

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

After distilling off the solvent in the reaction solution, an excess of methanol is added, solid-liquid separation means such as centrifugation is applied, the obtained precipitate is re-dispersed in a solvent such as toluene, and the same methanol as above. Repeat the wash several times. Then, the toluene dispersion liquid is filtered to remove sodium carbonate, whereby zirconia nanocrystal particles modified with PDMS-COOH residue (that is, PDMS-COO group) having a structure represented by the following formula (2) To obtain a dispersion containing

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

[Effect of this embodiment]
According to this embodiment, not only the dispersive contribution portion to the dispersion medium such as organosiloxane, the modification portion such as carboxyl group of carboxylic acid but also a predetermined carbon skeleton in one molecule and By modifying the surface of the zirconia nanocrystal with a compound provided with a portion capable of imparting stability to dispersibility, stable solvent dispersibility can be imparted.

Second Embodiment
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, which is crosslinked and cured in the thermosetting silicone resin matrix, and the zirconia nano-porous material is surface-modified with the above-mentioned POS-COOH residue, preferably PDMS-COOH residue. It is characterized in that crystal particles are dispersed.

The zirconia nanocrystal particles surface-modified with the above POS-COOH residue, preferably PDMS-COOH residue, have a siloxane unit in the modifier, so they are crosslinked and cured in a thermosetting silicone resin (ie, dispersed) Very well and in a stable manner).

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, and preferably 10 to 50% by mass as ZrO ₂ from the viewpoint of improvement of the refractive index and dispersibility. More preferable.
When the content of nanocrystalline particles is less than 5% by mass, the improvement of the refractive index has little meaning.
On the other hand, when the content of the nanocrystal particles exceeds 80%, the possibility of devitrification due to the aggregation of the particles increases, and even if it is transparent, it is extremely fragile, and the properties of the resin are impaired.
From the viewpoint of achieving both the improvement of the refractive index and the 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 said silicone type composite material can be efficiently manufactured according to the method of this embodiment shown below.

The method for producing the silicone-based composite material of the present invention is
(A) Preparation of mixed solution containing thermosetting silicone resin, organic solvent dispersion of zirconia nanocrystal particles surface-modified with the above POS-COOH residue, preferably PDMS-COOH residue, and curing catalyst The process to
(B) distilling off the solvent in the liquid mixture;
(C) heat treating the mixture after evaporation of the solvent to crosslink and cure the thermosetting silicone resin.

As a thermosetting silicone resin used at the said (a) process, the mixture of an addition reaction type silicone resin and a silicone type crosslinking agent can be used. As this addition reaction type silicone resin, for example, at least one selected from polyorganosiloxanes having an alkenyl group as a functional group in the molecule can be mentioned.
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. .

As a silicone type crosslinking agent, for example, a polyorganosiloxane having at least two silicon-bonded hydrogen atoms in one molecule, specifically, a dimethylhydrogensiloxy end-capped dimethylsiloxane-methylhydrogensiloxane copolymer, Examples thereof include trimethylsiloxy end-capped dimethylsiloxane-methyl hydrogen siloxane copolymer, trimethylsiloxane end-capped poly (methyl hydrogen siloxane), poly (hydrogensilsesquioxane) and the like.

Further, as a curing catalyst, a platinum compound is usually used. Examples of the platinum-based compound include particulate platinum, particulate 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 the present embodiment, the highly colorless and transparent zirconia nanocrystal particle-containing silicone resin dispersion can be obtained by the steps (a) and (b).
Next, in step (c), the thermosetting resin is crosslinked and cured by heating the silicone resin dispersion, for example, at a temperature of 100 to 200 ° C. for about 1 to 12 hours. A base composite material is obtained.

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

According to this embodiment, the surface-modified zirconia nanocrystal particles capable of stably maintaining good dispersibility in the dispersion medium can be contained in the thermosetting silicone resin matrix with high 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 specific effects obtained by the constituent elements of the invention and the combination thereof can be derived.
Therefore, in the present embodiment, various modifications in the first embodiment will be described. The points not particularly mentioned are the same as in the first embodiment.

In the first embodiment, the compound having the modifying portion, the stability contributing portion and the dispersibility contributing portion in one structural formula is mentioned, and as a specific example thereof, a fat having both the modifying portion and the stability contributing portion Are listed for the group carboxylic acid residue.
On the other hand, as long as the zirconia nanoparticles can be modified, it may be considered that they may not be aliphatic carboxylic acid residues. For example, ketone groups or aldehyde groups may be applicable.
In addition, with respect to the stability contributing portion made of a carbon skeleton, a predetermined number of carbon chains may be bonded to these modified portions.

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

In addition, about a modification part, a stability contribution part, and a dispersibility contribution part, if another functional group, a carbon chain, etc. are combined to the functional group in each part, if each function can be exhibited, here Those containing other functional groups and carbon chains mentioned in the above are referred to as a modified portion, a stability contributing portion and a dispersive contributing portion.

On the other hand, not the zirconia nanoparticles modified by aliphatic carboxylic acid residues, but also the steps before this modification is performed, that is, the steps modified by aryl sulfonic acid residues are also described.
In Embodiment 1, the arylsulfonic acid residue is described, but what can be used for the pretreatment is not limited to the arylsulfonic acid residue, as long as it can be substituted by the above-mentioned compound later. For example, organic sulfonic acids other than aryl sulfonic acids may be used, and those having a ketone group or an aldehyde group may be applicable.

EXAMPLES The present invention will next be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Example 1
[1. Preparation 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 made to melt | dissolve in the mixed solvent of 20 ml of pharmaceutical industry and 5 ml of triethyl orthoformates (made by Kanto Chemical Co., Ltd.).

The solution was filled in a pressure vessel (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 released. At this time, the reaction solution was clear and colorless, and no precipitation was observed.

After removing the solvent of the reaction solution with an evaporator under reduced pressure, 670 mg of white powdery 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, uniform redispersion is possible and a 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 is a tetragonal zirconium oxide crystal. In addition, as a result of observation by infrared spectroscopy (IR), it is confirmed that PTSH is chemically bonded to the surface of the zirconia nanoparticles as the white powder PTSH surface-modified zirconia nanocrystal particles.
In addition, as a result of observation by a transmission electron microscope (TEM), it was confirmed that the crystal was a microcrystal with a diameter of 2 to 3 nm. Further, when the compositional ratio of the product was measured by elemental analysis using inductively coupled plasma atomic emission (ICP-AES), it was found that Zr / S = 4.06 [molar ratio].

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

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

Next, the reaction solution was subjected to an evaporator, and then 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 wash was repeated several times.

The obtained toluene dispersion is filtered to remove sodium carbonate, p-toluenesulfonic acid is substituted, and a dispersion of zirconia nanocrystals surface-modified with PDMS-COOH residues (ie PDMS-COO group) is obtained. It was done. 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 substitution, whereas it was Zr / S after substitution. It became = 431 [mol ratio], and sulfur almost disappeared to Zr.

As described above, it was confirmed that the surface modifier of the surface of the zirconia nanocrystal particle was substituted from a PTSH to a PDMS-COOH residue because the sulfur almost disappeared.
In addition, it was confirmed by IR measurement that the PDMS-COOH residue was surface-modified on the nanocrystal particle surface. Furthermore, it was confirmed by the observation of XRD and TEM that the portion of the zirconia nanocrystal did not change from the nanocrystal obtained in Example 1. That is, it was confirmed that the crystal form was a tetragonal zirconium oxide crystal as it was, and it was a microcrystalline with a diameter of 2 to 3 nm.

Example 2
The surface-modified zirconia nanocrystals obtained in the above (1) were added to 2 g of “SS-6001” (thermosetting silicone resin) A and B mixed in equal amounts by Saint-Yurek Co., Ltd. 1 g of a toluene dispersion of particles was added as ZrO ₂ and mixed well to prepare a mixture.

Then, the solvent in the mixture was distilled off with 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 heated and cured in an oven at 160 ° C. for 12 hours to obtain a transparent ZrO ₂ -silicone composite material.

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

A modification for surface-modifying zirconia nanoparticles;
A stability contribution consisting of a carbon skeleton bound to said modification;
A dispersive contribution to a dispersion medium comprising a polymer chain coupled to the stability contributing part;
Surface-modified zirconia nanocrystal particles characterized in that the zirconia nanoparticles are modified by a compound provided in one molecule.
The dispersibility contributing portion is a polyorganosiloxane chain having 4 to 100 organosiloxane units,
A combination of the stability contributing portion and the modifying portion is a group derived from an aliphatic carboxylic acid, and is an aliphatic carboxylic acid residue having 2 to 18 carbon atoms in the aliphatic group,
The surface-modified zirconia nanocrystal particle according to claim 1, wherein the surface of the zirconia nanoparticle is modified with the aliphatic carboxylic acid residue.
The surface-modified zirconia nanocrystal particle 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 particle 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 arylsulfonic acid residue which may have a substituent on an aromatic ring in an organic solvent;
A modification for surface modification of zirconia nanoparticles, a stability contributing part comprising a carbon skeleton binding to the modifying part, and a dispersion contributing part comprising a polymer chain binding to the stable dispersion contributing 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 comprising the surface-modified zirconia nanocrystal particles according to any one of claims 1 to 5 dispersed in a thermosetting silicone resin matrix formed by crosslinking and curing.
The silicone-based composite material according to claim 8, wherein the content of the surface-modified 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 liquid mixture;
(C) heat treating the mixture after evaporation of the solvent to crosslink and cure the thermosetting silicone resin;
A method of producing a silicone based composite material, comprising: