JP2956293B2 - Highly transparent silica-titania particles and method for producing the same - Google Patents

Abstract

PURPOSE:To surely obtain excellent transparency of silica-titania particles by reacting a silicon alkoxide, etc., so as to provide given refractive index and linear percent transmission, grinding and sintering and vitrifying. CONSTITUTION:An silicon alkoxide and a titanium alkoxide are hydrolyzed and subjected to polycondensation to give a silica-titania sol, which is gelatinized, dried, ground into a given particle size and sintered and vitrified to produce highly transparent silicatitania particles (A) having 1.50-1.53 refractive index. Then a bisphenol type epoxy resin shown by the formula (n is 0-10), etc., are blended with one or more selected from glycidyl ethers to prepare a solution (B) so as to give difference in refractive index between the component (B) and the component (A) of + or -0.0005. Then the solution is mixed with the component (A) having 5-30mum average particle diameter in the weight ratio of 1:1 to give a mixture (C). Then the linear percent transmission of the component (C) is measured in a wavelength range of 900-600nm at 1mm optical path length to determine the component (A) having >=60% linear percent transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to highly transparent silica-titania particles suitably used as a filler for molding compounds for encapsulating optical functional devices such as LEDs, and a method for producing the same.

[0002]

2. Description of the Related Art At present, optical functional devices such as LEDs, LDs, CCDs, photodiodes, and photocouplers are
Although mainly sealed with a ceramic package or transparent plastic, an epoxy molding compound in which a filler is filled with an epoxy resin is demanded as a novel sealing material for these devices.

Such a filler is required not only to have a high light transmittance but also to have a refractive index equivalent to that of an epoxy resin in order to prevent a decrease in the transmittance due to light scattering. By blending a filler having both high light transmittance and a refractive index equivalent to that of an epoxy resin into a transparent epoxy resin, it is possible to obtain an epoxy molding compound having excellent transparency.

[0004] The present inventors have already filed Japanese Patent Application No. 2-2807.
No. 7, etc., proposed a highly transparent silica-titania particle which can be suitably used as the above-mentioned filler, and a method for producing the same. The highly transparent silica-titania particles are filled in a transparent epoxy resin to obtain an epoxy molding compound having excellent transparency.

[0005]

However, according to the above-mentioned Japanese Patent Application No. 2-28077, the present inventors have proposed a highly transparent silica having a refractive index (n _D ) of 1.46 to 1.58 over a wide range. When attempting to produce titania particles, the refractive index (n _D ) is from 1.46 to less than 1.50 and 1.53
In the range of 1.58 is certainly highly transparent silica - although titania particles is obtained, in the range refractive index (n _D) is less than 1.50 or more 1.53, silica - anatase titania particles (Anatase) Fine crystals were precipitated, and highly transparent ones were difficult to obtain.

[0006] As described above, the silica-titania particles having a low transmittance value, in which the microcrystals are precipitated, are difficult to use as the filler of the epoxy molding compound for an optical function device described above.

Therefore, in order to obtain an epoxy molding compound having excellent transparency by using silica-titania particles, it is necessary to avoid the range of the refractive index (n _D ). , The composition was restricted.

[0008] The present invention has been made in view of the above circumstances,
Silica-titania particles having high light transmittance even in the range of refractive index (n _D ) of 1.50 or more and less than 1.53, which can be suitably used as a filler for epoxy molding compounds for optical functional devices, and production thereof The aim is to provide a method.

[0009]

Means and Action for Solving the Problems The present inventors have
As a result of intensive studies to achieve the above object, a silica-titania sol obtained by hydrolyzing and polycondensing silicon alkoxide and titanium alkoxide is gelled and dried, and then the dried gel is pulverized to a predetermined particle size. In the method for producing silica-titania particles by vitrification by sintering, it is represented by the following formula (3): Si (OR ¹ ) ₄ (3) (where R ¹ is an alkyl group having 1 to 4 carbon atoms). And a partial hydrolyzate obtained by reacting a silicon alkoxide with an acidic aqueous solution with the following formula (4): Ti (OR ² ) ₄ ... (4) (where R ² is an alkyl group having 1 to 4 carbon atoms). Is further hydrolyzed and polycondensed with an acidic aqueous solution to obtain a partial condensate with titanium alkoxide.
Even if the refractive index (n _D ) is 1.50 or more and less than 1.53, 900 nm to 60 by the following linear transmittance measurement method A.
It has been found that highly transparent silica-titania particles having a linear transmittance of 60% or more in a wavelength range of 0 nm can be obtained.

A: A mixture of a bisphenol type epoxy resin represented by the following general formula (1) or a novolak type epoxy resin represented by the following general formula (2) and one or more selected from glycidyl ethers Then, a solution is prepared in which the difference in the refractive index from the silica-titania particles is within ± 0.0005. This solution and silica-titania particles pulverized to an average particle size of 5 to 30 μm are mixed at a weight ratio of 1: 1, and the mixture is measured for linear transmittance with an optical path length of 1 mm.

[0011]

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That is, Japanese Patent Application No. 2-2 proposed by the present inventors.
In the method for producing silica-titania particles of No. 8077, a partial hydrolyzate obtained by reacting a silicon alkoxide with an acidic aqueous solution and a partial condensate obtained by reacting a titanium alkoxide are further hydrolyzed and polycondensed with water. , the refractive index in such a way (n _D) is in the range of less than 1.50 or more 1.53, highly transparent silica - titania particles were those difficult to obtain.

However, the present inventors have proposed that a partial hydrolyzate obtained by reacting a silicon alkoxide with an acidic aqueous solution and a partial condensate obtained by reacting a titanium alkoxide with a titanium alkoxide is further subjected to hydrolysis and polycondensation with an acidic aqueous solution instead of water. By doing so, even in the range where the refractive index (n _D ) is 1.50 or more and less than 1.53, 900 nm to 600 nm according to the above-described test method A.
It has been found that silica-titania particles having a high linear transmittance in a wavelength range of 60% or more and having no anatase microcrystals can be finally obtained.

The reason for this is that a large amount of titanium alkoxide monomer is present in a partial condensate obtained by reacting a titanium alkoxide with a partial hydrolyzate obtained by reacting a silicon alkoxide with an acidic aqueous solution. In the production method, the condensation reaction rate of titanium alkoxide is very high in the next hydrolysis and polycondensation steps, so that TiO ₂
Microcrystals are likely to be generated in the subsequent sintering step after the block is formed, whereas, when the above-mentioned hydrolysis and polycondensation reaction is performed with an acidic aqueous solution as in the present invention,
It is considered that the following three types of condensation reactions could be more uniformly caused because the condensation reaction rate of titanium alkoxide can be sufficiently suppressed.

[0015]

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Therefore, according to the present invention, the refractive index (n _D ) is 1.
A highly transparent silica-titania particle having a linear transmittance of 60% or more in a wavelength range of 900 nm to 600 nm according to the linear transmittance measurement method A of 50 to 1.53, and silicon alkoxide and titanium alkoxide; Is hydrolyzed and polycondensed to form a silica-titania sol, which is then gelled and dried, and then the dried gel is pulverized to a predetermined particle size and sintered and vitrified to produce silica-titania particles. ) Si (OR ¹ ) ₄ (3) (where R ¹ is an alkyl group having 1 to 4 carbon atoms) and a partial hydrolyzate obtained by reacting a silicon alkoxide represented by the following formula (4) ) Ti (the _{^{OR 2) 4 ... (4)}} ( where, R ² is a partial condensate of a titanium alkoxide represented by an alkyl group having 1 to 4 carbon atoms.), further acidic aqueous solution And a method for producing highly transparent silica-titania particles having a refractive index (n _D ) of 1.50 or more and less than 1.53, wherein a silica titania sol is obtained by hydrolysis and polycondensation reaction.

Hereinafter, the present invention will be described in more detail. To obtain highly transparent silica-titania particles according to the present invention, first, silicon alkoxide and titanium alkoxide are used as starting materials.

Here, the silicon alkoxide is as follows:
Notation (3) Si (OR¹)_Four … (3) (However, R¹Is an alkyl group having 1 to 4 carbon atoms. ) Is used, for example, Si (OCH_Three)_Four, Si (O
C_TwoH_Five)_FourAnd the like.

On the other hand, titanium alkoxide has the following formula
(4) Ti (OR^Two)_Four … (4) (However, R^TwoIs an alkyl group having 1 to 4 carbon atoms. ) Is used, for example, Ti (O-iso-C_ThreeH₇)
_Four, Ti (On-C_FourH₉)_FourAnd the like.

[0020] In this case, it is preferable to use a silicon alkoxide and a titanium alkoxide in an amount such that 8 to 12 mol% of TiO ₂ with respect to the total of SiO ₂ and TiO _2, thereby the refractive index (n _D ) Can be finally obtained in the range of 1.50 or more and less than 1.53.

As a method for obtaining a sol from these raw materials, the above-mentioned silicon alkoxide is dissolved in an alcohol such as methanol, ethanol, propanol or the like as a diluting solvent, and a stoichiometric amount or less of water containing an acid catalyst is added thereto. In addition, a method of preparing a silica-titania sol by adding a titanium alkoxide to a partially hydrolyzed silicon alkoxide to partially condense it and further adding water to prepare a silica-titania sol.

At this time, the partial hydrolyzate obtained by reacting the silicon alkoxide with the acidic aqueous solution and the partial condensate of the titanium alkoxide as in the present invention are further hydrolyzed and polycondensed with the acidic aqueous solution, thereby obtaining a refraction. Rate (n _D )
Is in the range of 1.50 to less than 1.53, highly transparent silica-titania particles can be produced.

Here, the kind of the acid used as the catalyst is not particularly limited, but a mineral acid such as hydrochloric acid, nitric acid and sulfuric acid, or an organic acid such as acetic acid and oxalic acid is preferably used.

The sol produced as described above is preferably transferred to a container for gelation, sealed, and then allowed to stand in a thermostatic drier for gelation.

If the gelation temperature and the aging temperature after gelation are lower than 60 ° C., the hydrolysis of the alkoxide may be incomplete. It is preferable to make the above. The aging may be performed for 1 hour or more, preferably 5 hours or more from the viewpoint of complete hydrolysis.

The method of drying the wet gel after the gelation and aging is not particularly limited. For example, the lid of the sealed container used for aging the gel is removed, and the lid is left as it is in a constant temperature drier. And drying to obtain a dried gel.

The dried gel is then pulverized, but the pulverization method is not particularly limited, and the particle size is appropriately selected. An appropriate pulverization method and particle size according to the application can be adopted. When used as a filler for stopping epoxy molding, the average particle size is 1 to 100 μm, particularly 5 to 30 μm.
It is preferable that

Next, the pulverized dried gel is sintered and vitrified, and the sintering temperature is preferably in the range of 1050 to 1250 ° C. If the sintering temperature is lower than 1050 ° C., the particles are not completely uniformly densified. Therefore, when the transmittance of the silica-titania particles is measured, the light incident on the inside of the particles is composed of silica-titania constituent particles and the constituent particles. Because of scattering due to the refractive index difference between the pores of the gap, the resulting transmittance value may be low, and if the sintering temperature is higher than 1250 ° C., even if hydrolysis, polycondensation occurs. Even when the reaction is carried out in the presence of an acid, precipitation of anatase microcrystals occurs.
In some cases, titania particles cannot be obtained.

The sintering method is not particularly limited as long as it is within the above-mentioned temperature range. However, a sintering furnace such as an electric furnace for maintaining a constant temperature is used, and air, oxygen gas or oxygen is supplied into the furnace. It is preferable to feed a gas mixture with air to make the inside of the furnace an oxidizing atmosphere. Further, it is preferable that the rate of temperature rise until reaching a predetermined temperature is usually 10 to 500 ° C./hour. The sintering time is usually 10 to 300 minutes in the above temperature range.

The silica-titania particles thus obtained have a refractive index difference of ± 0.0
One or two selected from a bisphenol-type epoxy resin of the following formula (1) or a novolak-type epoxy resin of the following formula (2) and glycidyl ethers prepared within 005:
And a silica-titania particle pulverized to an average particle size of 5 to 30 μm in a weight ratio of 1: 1.
When the linear transmittance of the mixture is measured with an optical path length of 1 mm, the linear transmittance in the wavelength range of 900 nm to 600 nm is 60% or more, and the refractive index (n _D ) is 1.50 or more. Even if it is less than 0.53, the transparency is excellent.

[0031]

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Therefore, the silica-titania particles of the present invention are suitable as a molding compound for encapsulating an optical function device, particularly as a filler for an epoxy resin, and a transparent epoxy resin and the silica-titania particles of the present invention are used in combination. 1m if molding compound is formed by
A highly transparent molding compound having a thickness of m and a light transmittance of 60% or more can be reliably obtained.

Further, in combination with the silica-titania particles according to the invention of Japanese Patent Application No. 2-28077 or the like, highly transparent silica-titania particles having a refractive index (n _D ) of 1.46 to 1.58 over a wide range. Since almost all types of transparent epoxy resins can be used, an epoxy molding compound having excellent transparency can be obtained.

[0034]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 1522.2 g of methyl orthosilicate (manufactured by Tama Chemical Industry) and methanol (Wako Pure Chemical, special grade) 3
180.0 g of a 0.2 N hydrochloric acid aqueous solution was added to the solution containing 20.4 g at 30 ° C., and the mixture was stirred for 1 hour. Thereto was gradually added a solution of 367.7 g of titanium tetrabutoxide (manufactured by Nisso) and 160.2 g of methanol, followed by 1 more
Stirred for hours. Thereafter, a 0.2 N hydrochloric acid aqueous solution 617.
8 g was added and stirred for another 10 minutes. The obtained silica-titania sol was placed in a polypropylene container,
Upon sealing at 0 ° C., the sol gelled after about 60 minutes.
The gel was aged as it was for 17 hours in a sealed state at 60 ° C. Thereafter, the lid of the container was removed, and dried in a dryer at 90 ° C. for 4 days to obtain a dried gel.

From the dried gel, 250 g was pulverized for 4 hours with a 2 liter alumina ball mill. The dried gel body after the pulverization is put into a box-type electric furnace, and nitrogen 1.5 m
After the temperature was raised to 500 ° C. for 5 hours under the condition of ³ / h, the temperature was raised to 1150 ° C. for 8 hours under the condition of 1.8 m ³ / h of dry air, and then kept at 1150 ° C. for 30 minutes to obtain the average particle size. Silica-titania particles having a diameter of 11.8 μm were obtained.

Example 2 1522.2 g of methyl orthosilicate
And 300.4 g of methanol at 30 ° C.
180.0 g of a normal aqueous hydrochloric acid solution was added, and the mixture was stirred for 1 hour. Thereto was gradually added a solution of 404.8 g of titanium tetrabutoxide and 160.2 g of methanol, and the mixture was further stirred for 1 hour. Then, 0.2N hydrochloric acid aqueous solution 62
5.6 g was added and stirred for another 10 minutes. The obtained silica-titania sol was gelled in the same manner as in Example 1,
Dry and pulverized.

The dried gel body after the pulverization is placed in a box-type electric furnace, heated to 500 ° C. for 5 hours under a condition of 1.5 m ³ / h of nitrogen, and then dried under a condition of 1.8 m ³ / h of dry air. 1100
The temperature was raised to 8 ° C. for 8 hours, and then maintained at 1100 ° C. for 30 minutes to obtain silica-titania particles having an average particle size of 10.2 μm.

Comparative Example 1 1522.2 g of methyl orthosilicate
And 300.4 g of methanol at 30 ° C.
180.0 g of a normal aqueous hydrochloric acid solution was added, and the mixture was stirred for 1 hour. After a solution of 367.7 g of titanium tetrabutoxide and 160.2 g of methanol was gradually added thereto, the mixture was further stirred for 1 hour. Thereafter, 617.8 g of pure water was added,
Stir for another 10 minutes. The obtained silica-titania sol was gelled, dried and pulverized in the same manner as in Example 1.

The pulverized dried gel body was placed in a box-type electric furnace, heated to 500 ° C. for 5 hours under a condition of 1.5 m ³ / h of nitrogen, and then dried under a condition of 1.8 m ³ / h of dry air. 1100
The temperature was raised to 8 ° C. for 8 hours and then kept at 1100 ° C. for 30 minutes to obtain silica-titania particles having an average particle size of 9.2 μm.

Comparative Example 2 1522.2 g of methyl orthosilicate
And 300.4 g of methanol at 30 ° C.
180.0 g of a normal aqueous hydrochloric acid solution was added, and the mixture was stirred for 1 hour. After a solution of 367.7 g of titanium tetrabutoxide and 160.2 g of methanol was gradually added thereto, the mixture was further stirred for 1 hour. Thereafter, 617.8 g of pure water was added,
Stir for another 10 minutes. The obtained silica-titania sol was gelled, dried and pulverized in the same manner as in Example 1.

The pulverized dried gel body was placed in a box-type electric furnace, heated to 500 ° C. in 5 hours under a condition of 1.5 m ³ / h of nitrogen, and then dried under a condition of 1.8 m ³ / h of dry air. 1100
The temperature was raised to 8 ° C. for 8 hours, and then kept at 1100 ° C. for 30 minutes to obtain silica-titania particles having an average particle size of 9.3 μm.

The results of the light transmittance and the refractive index (n _D ) of each silica-titania particle are shown in Table 1. The methods for measuring the average particle diameter, the refractive index (n _D ), and the light transmittance are as follows. Measurement method of particle size distribution As a dispersion medium of a sample, sodium hexametaphosphate of 0.2 was used.
The weight% aqueous solution was used and measured with a Shimadzu centrifugal sedimentation type particle size distribution analyzer SA-CP3L. Measurement method of refractive index It was measured by Abago refractometer 3T manufactured by Atago Co., Ltd. Method of measuring transmittance The silica-titania particles having an average particle diameter of 5 to 30 μm and the epicoat 828 (oiling shell) of the above formula (1) in which the mixing ratio is adjusted so that the refractive index of the particles is in the range of ± 0.0005. (Epoxy resin manufactured by Epoxy Co., Ltd.) and a mixed solution of GE-100 (same as above) and phenyl glycidyl ether as glycidyl ether are mixed at a weight ratio of 1: 1. After fully dispersing the particles, the mixture is
, And deaerated under reduced pressure until no bubbles are visually observed. Then, the transmission spectrum is measured in a wavelength range of 900 nm to 600 nm using a spectrophotometer. In this case, the reference is blank.

[0044]

[Table 1]

[0045]

As described above, the highly transparent silica-titania particles of the present invention have excellent transparency even though the refractive index (n _D ) is 1.50 or more and less than 1.53. It can be suitably used as a filler or the like for a transparent epoxy molding compound of an optical function device, and according to the method for producing highly transparent silica-titania particles of the present invention, the silica having excellent transparency -It is possible to reliably produce titania particles.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C08L 63/00 C08L 63/00 (56) References JP-A-3-279210 (JP, A) JP-A-3-232741 (JP , A) JP-A-64-76935 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C03C 1/00-14/00 C01B 33/00-39/54 C01G 1/00 -23/08

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the refractive index is not less than 1.50 and less than 1.53, and is from 900 nm to 6 according to the following linear transmittance measurement method A
Highly transparent silica-titania particles having a linear transmittance of 60% or more in a wavelength range of 00 nm. A: A mixture of a bisphenol type epoxy resin represented by the following general formula (1) or a novolak type epoxy resin represented by the following general formula (2) and one or more selected from glycidyl ethers, and silica -Prepare a solution having a difference in refractive index from the titania particles within ± 0.0005. This solution and silica-titania particles pulverized to an average particle size of 5 to 30 μm are mixed at a weight ratio of 1: 1, and the mixture is measured for linear transmittance with an optical path length of 1 mm. Embedded image 2. A silica-titania sol obtained by hydrolyzing and polycondensing a silicon alkoxide and a titanium alkoxide is gelled and dried, and the dried gel is pulverized to a predetermined particle size, sintered and vitrified to obtain silica-titania. In the method for producing particles, a silicon alkoxide represented by the following formula (3): Si (OR ¹ ) ₄ (3) (where R ¹ is an alkyl group having 1 to 4 carbon atoms) is reacted with an acidic aqueous solution. Partial condensate of the partially hydrolyzed product and a titanium alkoxide represented by the following formula (4): Ti (OR ² ) ₄ (4) (where R ² is an alkyl group having 1 to 4 carbon atoms) Is further hydrolyzed and polycondensed in an acidic aqueous solution to obtain a silica titania sol, wherein the highly transparent silica-titania particles having a refractive index of 1.50 or more and less than 1.53 are obtained. The method of production.