JP2018203572A - Transparent silica glass and method for producing the same - Google Patents

Abstract

To provide a transparent silica glass that is free from darkening or the like and has high transparency, and can be easily produced.SOLUTION: A transparent silica glass is a sintered body of a composition containing (A) component: spherical silica particles with an average particle size of 0.01-150 μm and an aspect ratio of 1.00-1.50, of 80-99.9 pts.mass, and (B) component: an organopolysiloxane composition with a 23°C refractive index of 1.40-1.55 and a 23°C viscosity of 0.1-10,000 mPa s, containing a hydrosilylation reaction catalyst, of 0.1-20 pts.mass.SELECTED DRAWING: None

Description

  The present invention relates to a transparent silica glass and a method for producing the same.

  Currently, the white LED market is expanding greatly, and as the brightness of the chip increases, high heat resistance and high impact resistance of the resin are required. Currently, silicone is mainly used for high brightness LEDs.

  Recently, UV LEDs have been developed for sterilization applications. Since the UV LED has an emission wavelength of 400 nm as a main emission wavelength, very high heat resistance, impact resistance, and discoloration resistance are required. However, decomposition of silicone proceeds in the UV region, and problems such as cracks and discoloration have occurred.

  Therefore, at present, most of the LED structures do not contain organic components, and glass or the like is hermetically sealed with a reflector immediately above the UV LED chip. However, when using glass with a short wavelength and low absorption, there is only quartz glass, and the price is very expensive, and the glass structure can only be a flat plate structure, and there are various lens structures and Fresnel structures. It was difficult to install.

  Glass sintered bodies produced by molding and sintering a kneaded product of inorganic powder and binder have been known for some time, but it was difficult to obtain a highly pure and highly transparent product (patent) Reference 1). Moreover, although the manufacturing method which uses polyvinyl alcohol (PVA) as a binder is disclosed, PVA has many carbon components, and not only the transparency on the short wavelength side in the sintered body is deteriorated, but also degreasing to remove the carbon components. Since the process and sintering took time, it was difficult to achieve mass production (Patent Document 2). As these improvements, a method for producing a transparent silica glass by molding and sintering an inorganic powder, which is a ceramic-forming material, using methylcellulose, methylhydroxyethylcellulose or the like as a binder has been found (Patent Documents 3 and 4). ). However, when these cellulose derivatives are used as binders, the moldability is good, but there are many impurities that cause devitrification after sintering, which is insufficient to obtain a glass sintered body having high transparency.

JP 2008-266087 A JP 2009-007185 A JP 2009-120444 A JP 2013-525156 A

  In view of the above circumstances, an object of the present invention is to provide a transparent silica glass which is free from dullness and is highly transparent and can be easily manufactured. Moreover, it aims at providing the manufacturing method which can manufacture highly transparent transparent silica glass easily by shortening the time concerning a degreasing process.

In order to solve the above problems, in the present invention,
The following (A) component and (B) component;
(A) Spherical silica particles having an average particle diameter of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) The refractive index at 23 ° C. is 1. An organopolysiloxane composition having a viscosity of 40 to 1.55 and a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s and containing a hydrosilylation reaction catalyst: baking of a composition containing 0.1 to 20 parts by mass A transparent silica glass which is a bonded body is provided.

  If it is transparent silica glass like this invention, it will be transparent silica glass which is highly transparent without dullness etc. and can be manufactured easily.

At this time, the (B) component is the following (B1) component, (B2) component, and (B3) component;
(B1) Organopolysiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule (B2) Organopolysiloxane having a hydrogen atom bonded to two or more silicon atoms in one molecule: (B1 ) An amount such that the total number of hydrogen atoms bonded to silicon atoms in the component (B2) is 0.5 to 8.0 with respect to the total number of alkenyl groups in the component (B3) Hydrosilylation reaction catalyst: catalyst An organopolysiloxane composition containing the amount is preferred.

  Such a component (B) is suitable as a binder, and the volatilization of the unreacted component (B2) and the hydrogen atom (hydrosilyl group, SiH group) bonded to the silicon atom in the component (B2) are decomposed. Thus, there is no fear that hydrogen gas is generated, and the transparent silica glass is free from the occurrence of voids and cracks.

（式中、Ｒ^１は独立して炭素数１〜１０の１価炭化水素基であり、Ｒ^１のうち２個以上は炭素数２〜１０のアルケニル基であり、ａは０〜０．７、ｂは０〜０．９、ｃは０〜０．９９、ｄは０．０５〜０．７であり、但しａ＋ｂ＋ｃ＋ｄ＝１．０である。）
で示されるアルケニル基含有オルガノポリシロキサン
（Ｂ２）下記平均組成式（２）

（式中、Ｒ^２は独立して炭素数１〜７の１価飽和炭化水素基及び炭素数６〜７の芳香族炭化水素基から選ばれる基であり、ｅは０．６〜２．０、ｆは０．４〜１．０の正数であり、但しｅ＋ｆ＝１．０〜２．５である。）
で示され、１分子中に２個以上のケイ素原子に結合した水素原子を有するハイドロジェンオルガノポリシロキサン
（Ｂ３）白金族金属系触媒
であることが好ましい。 In addition, the components (B1) to (B3) are
(B1) The following formula (1)

(In the formula, R ¹ is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, two or more of R ¹ are alkenyl groups having 2 to 10 carbon atoms, and a is 0 to 0.7. B is 0 to 0.9, c is 0 to 0.99, and d is 0.05 to 0.7, provided that a + b + c + d = 1.0.
(B2) The following average composition formula (2)

(In the formula, R ² is independently a group selected from a monovalent saturated hydrocarbon group having 1 to 7 carbon atoms and an aromatic hydrocarbon group having 6 to 7 carbon atoms, and e is 0.6 to 2.0. , F is a positive number of 0.4 to 1.0, where e + f = 1.0 to 2.5.)
It is preferable that it is a hydrogenated organopolysiloxane (B3) platinum group metal-based catalyst having a hydrogen atom bonded to two or more silicon atoms in one molecule.

  If it is such (B1)-(B3) component, it will become transparent silica glass without a void and a crack more reliably and easily.

  Further, the component (B) preferably has a residual rate of 40% or more in TGA analysis measured by the method described in JIS K 7120: 1987 at a maximum temperature of 1,000 ° C. in air.

  With the component (B) as described above, there is no risk of generating large voids between the spherical silica particles during degreasing and sintering of the composition, and there is no risk of cracks and devitrification occurring after sintering. It becomes.

In the present invention, the following components (A) and (B):
(A) Spherical silica particles having an average particle diameter of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) The refractive index at 23 ° C. is 1. Organopolysiloxane composition having a viscosity of 40 to 1.55 and a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s and containing a hydrosilylation reaction catalyst: A composition containing 0.1 to 20 parts by mass is prepared. After the step of forming, the step of forming the composition to form a molded body, then the step of heating the molded body at 400 to 1,200 ° C. for 10 minutes to 12 hours to degrease, and the degreased molding A method for producing a transparent silica glass comprising a step of heating and sintering a body at 1,400 to 1,800 ° C. for 1 to 60 minutes is provided.

  If it is a manufacturing method like this invention, the time concerning a degreasing process can be shortened and a highly transparent transparent silica glass without dullness etc. can be manufactured easily.

At this time, as the component (B), the following component (B1), component (B2), and component (B3);
(B1) Organopolysiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule (B2) Organopolysiloxane having a hydrogen atom bonded to two or more silicon atoms in one molecule: (B1 ) An amount such that the total number of hydrogen atoms bonded to silicon atoms in the component (B2) is 0.5 to 8.0 with respect to the total number of alkenyl groups in the component (B3) Hydrosilylation reaction catalyst: catalyst It is preferred to use an organopolysiloxane composition containing the amount.

  With such a production method using the component (B), the volatilization of the unreacted component (B2) and the hydrogen atom (hydrosilyl group, SiH group) bonded to the silicon atom in the component (B2) are decomposed. Therefore, it is possible to easily produce a transparent silica glass that does not generate hydrogen gas and does not generate voids and cracks.

（式中、Ｒ^１は独立して炭素数１〜１０の１価炭化水素基であり、Ｒ^１のうち２個以上は炭素数２〜１０のアルケニル基であり、ａは０〜０．７、ｂは０〜０．９、ｃは０〜０．９９、ｄは０．０５〜０．７であり、但しａ＋ｂ＋ｃ＋ｄ＝１．０である。）
で示されるアルケニル基含有オルガノポリシロキサン
（Ｂ２）下記平均組成式（２）

（式中、Ｒ^２は独立して炭素数１〜７の１価飽和炭化水素基及び炭素数６〜７の芳香族炭化水素基から選ばれる基であり、ｅは０．６〜２．０、ｆは０．４〜１．０の正数であり、但しｅ＋ｆ＝１．０〜２．５である。）
で示され、１分子中に２個以上のケイ素原子に結合した水素原子を有するハイドロジェンオルガノポリシロキサン
（Ｂ３）白金族金属系触媒
を用いることが好ましい。 Moreover, as said (B1)-(B3) component,
(B1) The following formula (1)

(In the formula, R ¹ is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, two or more of R ¹ are alkenyl groups having 2 to 10 carbon atoms, and a is 0 to 0.7. B is 0 to 0.9, c is 0 to 0.99, and d is 0.05 to 0.7, provided that a + b + c + d = 1.0.
(B2) The following average composition formula (2)

(In the formula, R ² is independently a group selected from a monovalent saturated hydrocarbon group having 1 to 7 carbon atoms and an aromatic hydrocarbon group having 6 to 7 carbon atoms, and e is 0.6 to 2.0. , F is a positive number of 0.4 to 1.0, where e + f = 1.0 to 2.5.)
It is preferable to use a hydrogen organopolysiloxane (B3) platinum group metal-based catalyst having a hydrogen atom bonded to two or more silicon atoms in one molecule.

  If it is a manufacturing method using such (B) component, the high quality transparent silica glass without a void and a crack can be manufactured more reliably easily.

  Furthermore, it is preferable to include a step of heating and purifying the compact at 1,000 to 1,500 ° C. for 0.5 to 5 hours in a hydrogen chloride gas atmosphere before the sintering step.

  Thus, if it is a manufacturing method including the process to refine | purify, the transparent silica glass by which generation | occurrence | production of devitrification was further suppressed can be manufactured by removing the impurity which may cause devitrification at the time of sintering.

  At this time, as the component (B), a component having a residual rate of 40% or more in TGA analysis measured by the method described in JIS K 7120: 1987 at a maximum temperature of 1,000 ° C. in air. preferable.

  If it is a manufacturing method using the above (B) component, there is no possibility that a big space | gap will generate | occur | produce between spherical silica particles at the time of degreasing and sintering of a composition, and there exists a possibility that a crack and devitrification may arise after sintering. It is possible to easily produce a transparent silica glass free from any problem.

  As described above, if the transparent silica glass of the present invention, by using an organopolysiloxane composition containing silicon and oxygen as constituent elements of silica as a binder, it causes devitrification to remain in the order of ppm. The resulting transparent silica glass can be reduced as much as possible, has no dullness, has very high transparency, and has excellent transmittance over a wide range of wavelengths. Moreover, the transparent silica glass of the present invention can be easily produced, and becomes a high-precision transparent silica glass that does not cause the occurrence of voids or cracks. By using such a transparent silica glass of the present invention, an inexpensive and high-quality UV package can be easily produced without using an expensive quartz glass. Moreover, if it is a manufacturing method of the transparent silica glass of this invention, since an organic group can be reduced as much as possible by using an organopolysiloxane composition as a binder, the degreasing process for burning the carbon component in a binder In addition, since the binder becomes silica when the reaction proceeds at a high temperature, the volume shrinkage during degreasing and sintering can be reduced to the minimum unlike conventional binders. Therefore, there is no fear of voids and cracks, and the above highly transparent and highly accurate transparent silica glass can be easily produced.

  As described above, there has been a demand for the development of a transparent silica glass that has no dullness and is highly transparent and can be easily produced, and a method for producing the same.

  As a result of intensive studies to achieve the above object, the inventors of the present invention can shorten the time of the degreasing process by using the organopolysiloxane composition as a binder, and further reduce the amount of impurities caused by the binder. Therefore, the present inventors have found that a highly transparent transparent silica glass can be easily produced and completed the present invention.

That is, the present invention includes the following components (A) and (B);
(A) Spherical silica particles having an average particle diameter of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) The refractive index at 23 ° C. is 1. An organopolysiloxane composition having a viscosity of 40 to 1.55 and a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s and containing a hydrosilylation reaction catalyst: baking of a composition containing 0.1 to 20 parts by mass It is a transparent silica glass which is a bonded body.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.
<Transparent silica glass>
(A) Spherical silica particles The spherical silica particles used in the present invention have an average particle diameter in the range of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50. The average particle diameter is preferably 0.05 to 100 μm, more preferably 0.1 to 10 μm. In the present invention, the average particle diameter of the spherical silica particles refers to the value of the volume average diameter of the particles measured by a dynamic light scattering method. Moreover, the aspect ratio of the spherical silica particles is preferably 1.00 to 1.40, and more preferably 1.00 to 1.20. In the present invention, the aspect ratio is a ratio of a major axis (D) to a minor axis (d), that is, a value measured as D / d by a photographed image by SEM.

  In addition, the spherical silica particles used in the present invention are synthesized by sol-gel method or chlorosilane hydrolysis rather than those produced from natural silica, and are spherical such as aluminum, sodium, iron, etc. by metal removal purification. It is preferable to use a material in which the amount of impurities often contained in silica particles is reduced to the limit. In the present invention, the amount of impurities refers to the element content measured by an inductively coupled plasma optical emission spectrometer (ICP-OES) and quantified by an absolute calibration curve method. The aluminum content in the spherical silica particles is preferably from 0.1 to 50 ppm, more preferably from 0.1 to 10 ppm. The lower the aluminum content, the better. However, considering the cost and the like, it is sufficient if it can be removed up to 0.1 ppm, and if it is 50 ppm or less, the crystallization of silica during sintering causes devitrification. Can be suppressed. Further, the sodium content in the spherical silica particles is preferably 0.01 to 1 ppm, more preferably 0.05 to 1 ppm. The smaller the sodium content, the better. However, considering the cost and the like, it is sufficient if it can be removed to 0.01 ppm, and if it is 1 ppm or less, the occurrence of devitrification during sintering can be suppressed. Further, the iron content in the spherical silica particles is preferably 0.1 to 5 ppm, more preferably 0.1 to 2 ppm. The lower the iron content, the better. However, considering the cost and the like, it is sufficient if it can be removed up to 0.1 ppm, and if it is 5 ppm or less, the occurrence of devitrification during sintering can be suppressed.

  Examples of the spherical silica particles include silica balloon, mesoporous silica, silica gel, crystalline silica such as stesovite and cristobalite, and quartz.

  (A) Content of a component is 80-99.9 mass parts in 100 mass parts of compositions for sintered compacts, Preferably it is 85-99.5 mass parts, More preferably, it is 90-99.5 mass parts. is there.

(B) Organopolysiloxane composition The organopolysiloxane composition used in the present invention has a refractive index of 1.40 to 1.55 at 23 ° C and a viscosity of 0.1 to 10,000 mPa · s at 23 ° C. Including a hydrosilylation reaction catalyst.

  The refractive index of the component (B) in the present invention refers to a value at a measurement wavelength of 589.3 nm (sodium D line) measured by an Abbe refractometer by the method described in JIS K 0062: 1992, and is 1.40. It is -1.55, Preferably it is 1.40-1.50, More preferably, it is 1.40-1.45. If it is out of this range, volume shrinkage during degreasing increases.

  The viscosity of the component (B) in the present invention refers to a value at 23 ° C. measured by a rotational viscometer according to the method described in JIS K 7117-1: 1999, and is preferably 0.1 to 10,000 mPa · s. Is 1 to 8,000 mPa · s, more preferably 1 to 1,000 mPa · s. Outside this range, when the spherical silica particles of the component (A) are highly filled, the component (B) does not conform to the silica surface, and voids are generated during degreasing and sintering.

  In the present invention, the component (B) preferably has a residual rate of 40% or more in TGA analysis measured by the method described in JIS K 7120: 1987 at a maximum temperature of 1,000 ° C. in air. More preferably, the residual rate is 40 to 60%. If the residual ratio is 40% or more, generation of large voids between the spherical silica particles can be suppressed during degreasing and sintering of the composition, and generation of cracks and devitrification after sintering can be suppressed.

The residual rate in the present invention is measured by, for example, measuring 10 mg of a sample with a TGA apparatus (Q500 manufactured by TA Instruments) and increasing the temperature increase rate from 25 ° C. to 1,000 ° C. at a rate of 20 ° C./min. And after hold | maintaining for 30 minutes at 1,000 degreeC, sample mass can be measured and it can obtain | require by a following formula.

(B) component used for this invention is the following (B1) component, (B2) component, and (B3) component;
(B1) Organopolysiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule (B2) Organopolysiloxane having a hydrogen atom bonded to two or more silicon atoms in one molecule: (B1) (B3) Hydrosilylation reaction catalyst: catalyst amount in which the total number of hydrogen atoms bonded to silicon atoms in component (B2) is 0.5 to 8.0 with respect to the total number of alkenyl groups in component The organopolysiloxane composition is preferably included.

  (B) Content of a component is 0.1-20 mass parts in 100 mass parts of compositions for sintered compacts, It is preferable that it is 0.1-10 mass parts, 0.1-5 mass parts It is more preferable that This will be described in detail below.

(B1) Organopolysiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule (B) Organopolysiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule constituting the component (B) (B1) serves as the main component constituting the component (B) of the present invention. The alkenyl group content contained in the component (B1) is preferably 0.0001 to 0.4 mol / 100 g, particularly preferably 0.005 to 0.1 mol / 100 g. As the component (B1), an alkenyl group-containing organopolysiloxane represented by the following formula (1) is preferable.

In the above formula, R ¹ is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, of which at least two are alkenyl groups having 2 to 10 carbon atoms, preferably 2 to 8 carbon atoms. is there. Examples of monovalent hydrocarbon groups for R ¹ include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, octyl, and nonyl groups. Alkyl groups such as decyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group; aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group Among them, a methyl group and a phenyl group are preferable, and examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, a cyclohexenyl group, an octenyl group, and the like. Of these, vinyl groups and allyl groups are preferred. a is 0 to 0.7, b is 0 to 0.9, c is 0 to 0.99, and d is 0.05 to 0.7, provided that a + b + c + d = 1.0.

The component (B1) may be a linear organopolysiloxane having at least one vinyl group on each silicon atom at both ends of the molecular chain represented by the following general formula (3). A branched structure (trifunctional siloxane unit) may be contained in the molecular chain. If it is a liquid organopolysiloxane having a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s, preferably 0.1 to 5,000 mPa · s, the spherical silica particles as the component (A) can be highly filled, etc. From the viewpoint of workability, curability and the like. In addition, the viscosity of the organopolysiloxane represented by the following general formula (3) is a value measured by a method using a rotational viscometer described in JIS K 7117-1: 1999.

In the above formula, R ¹ is as described above, and specific examples thereof include the same substituents as those exemplified in the above formula (1). R ³ is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, specifically a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, or a hexyl group, A methyl group and an ethyl group are preferred. g is 1, 2 or 3, preferably 1, and x is a number satisfying 1 ≦ x ≦ 1,000, preferably 5 ≦ x ≦ 500, more preferably 30 ≦ x ≦ 500.

  Specific examples of the organopolysiloxane represented by the above formula (3) include the following.

  In the above formula, x is the same as above, x1 is 0 ≦ x1 ≦ 1,000, x2 is 0 ≦ x2 ≦ 1,000, x1 + x2 = x, and y and z are 2 ≦ y ≦ 1, 000, 2 ≦ z ≦ 1,000.

(B2) Organopolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule (B) Organopolysiloxane having hydrogen atoms bonded to two or more silicon atoms in one molecule (B2) acts as a crosslinking agent in the component (B) of the present invention. The hydrogen atom (hydrosilyl group, SiH group) bonded to the silicon atom in the component (B2) and the component (B1) A cured product is formed by an addition reaction with an alkenyl group. The component (B2) is represented by the following average composition formula (2), and preferably contains at least two SiH groups in one molecule.

In the above formula (2), R ² is independently a group selected from a monovalent saturated hydrocarbon group having 1 to 7 carbon atoms, preferably 1 to 3 carbon atoms and an aromatic hydrocarbon group having 6 to 7 carbon atoms, Specific examples include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, and hexyl group, and aromatic hydrocarbon groups such as phenyl group, tolyl group, and benzyl group. Group or phenyl group.

  E is 0.6 to 2.0, preferably 0.6 to 1.8, f is 0.4 to 1.0, preferably 0.4 to 0.8, provided that e + f = 1.0. To 2.5, preferably 1.5 to 2.4. The position of the SiH group in the molecule is not particularly limited, and may be at the end of the molecular chain or in the middle.

  In addition, content of SiH group in (B2) component becomes like this. Preferably it is 0.001-0.5 mol / g, More preferably, it is 0.05-0.4 mol / g.

  The blending amount of the component (B2) is an effective curing amount of the component (B1). In particular, the SiH group in the component (B2) is based on the total amount of alkenyl groups (for example, vinyl groups) in the component (B1). It is preferably used in a molar ratio of 0.5 to 8.0, more preferably 0.8 to 6.0, particularly preferably 0.8 to 5.0, still more preferably 1.0 to 5.0. . If it is more than the said lower limit, hardening reaction will advance favorable. If the amount is not more than the above upper limit value, a large amount of unreacted SiH groups do not remain in the cured product, so that the unreacted (B2) component volatilizes during degreasing and sintering, or the SiH groups in the (B2) component There is no risk of decomposition and generation of hydrogen gas, and voids and cracks caused by these can be suppressed.

(B3) Hydrosilylation reaction catalyst (B3) The component hydrosilylation reaction catalyst is blended to promote the addition reaction between the alkenyl group in component (B1) and the hydrosilyl group in component (B2). Although platinum group metal catalysts such as palladium and rhodium can be used, platinum catalysts are preferred from the standpoint of cost. Examples of the platinum-based catalyst include H ₂ PtCl ₆ · mH ₂ O, K ₂ PtCl ₆ , KHPtCl ₆ · mH ₂ O, K ₂ PtCl ₄ , K ₂ PtCl ₄ · mH ₂ O, PtO ₂ · mH ₂ O ( m is a positive integer). In addition, a complex of the platinum catalyst and a hydrocarbon such as an olefin, an alcohol, or a vinyl group-containing organopolysiloxane can be used. The catalyst may be a single type or a combination of two or more types.

  What is necessary is just to mix | blend a hydrosilylation reaction catalyst with what is called a catalyst amount, for example, if it is a platinum group metal type catalyst, platinum group metal conversion (mass) with respect to 100 mass parts of total amounts of the said (B1) and (B2) component. The amount is preferably 0.0001 to 2 parts by mass, more preferably 0.0001 to 0.05 parts by mass.

Other Components In the component (B) of the present invention, components other than the components (B1), (B2), and (B3) described above can be blended as necessary. In addition, reaction inhibitors etc. are mentioned as an example of another component.

  The transparent silica glass of the present invention is a sintered body of such a composition. With such a transparent silica glass of the present invention, by using an organopolysiloxane composition containing silicon or oxygen as constituent elements of silica as a binder, impurities that cause devitrification remaining in the order of ppm. Can be reduced as much as possible, and there is no dullness and the transparency is very high, and it becomes a transparent silica glass excellent in transmittance at any wavelength. Moreover, the transparent silica glass of the present invention can be easily produced, and becomes a high-precision transparent silica glass that does not cause the occurrence of voids or cracks. By using such a transparent silica glass of the present invention, an inexpensive and high-quality UV package can be easily produced without using an expensive quartz glass.

<Method for producing transparent silica glass>
In the present invention, the following components (A) and (B):
(A) Spherical silica particles having an average particle diameter of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) The refractive index at 23 ° C. is 1. Organopolysiloxane composition having a viscosity of 40 to 1.55 and a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s and containing a hydrosilylation reaction catalyst: A composition containing 0.1 to 20 parts by mass is prepared. After the step of forming, the step of forming the composition to form a molded body, then the step of heating the molded body at 400 to 1,200 ° C. for 10 minutes to 12 hours to degrease, and the degreased molding A method for producing a transparent silica glass comprising a step of heating and sintering a body at 1,400 to 1,800 ° C. for 1 to 60 minutes is provided. Hereinafter, each step will be described in detail.

Composition preparation process In the manufacturing method of the transparent silica glass of this invention, the composition containing (A) component and (B) component is prepared first. In addition, about (A) component and (B) component, the thing similar to what was mentioned by description of the above-mentioned transparent silica glass can be used. The composition can be prepared by stirring, dissolving, mixing, and dispersing each of the above-described components simultaneously or separately, if necessary with heat treatment, and usually (B1), (B2) and (B3) It is preferable to mix the spherical silica particles (A) after mixing the component first to prepare the organopolysiloxane composition (B).

  The apparatus used for the operation such as stirring when mixing the spherical silica particles (A) into the prepared organopolysiloxane composition (B) is not particularly limited, but a lykai machine equipped with stirring and heating apparatus, three rolls, ball mill A planetary mixer, a rotation and revolution mixer, or the like can be used. Moreover, you may combine these apparatuses suitably.

Molding step Next, in the method for producing a transparent silica glass of the present invention, the composition prepared as described above is molded to form a molded body. The forming method is not particularly limited, and it may be formed into a desired shape by a known method.

Degreasing step In the method for producing the transparent silica glass of the present invention, the molded body formed as described above is then degreased by heating at 400 to 1,200 ° C. for 10 minutes to 12 hours. The carbon component is gradually removed by degreasing the silica-containing silicone resin composition. If there is no degreasing process, the carbon component remaining at the time of sintering will carbonize and cause devitrification. The degreasing step is performed in an atmosphere of helium gas or nitrogen gas other than hydrogen chloride gas, for example, at a maximum temperature of 400 to 1,200 ° C., preferably 500 to 1,000 ° C. for 10 minutes to 12 hours, preferably 1 to 6 hours. To do. If it is less than 400 ° C., degreasing does not proceed sufficiently and devitrification occurs during sintering. When the temperature exceeds 1,200 ° C., crystallization of silica proceeds and devitrification occurs.

Purification process In the method for producing the transparent silica glass of the present invention, a purification process, which is a process of removing Al, Na, Fe and the like, may be incorporated before the sintering process. When performing the purification step, the maximum temperature is 1,000 to 1,500 ° C., preferably 1,000 to 1,300 ° C., more preferably 1,100 to 1,300 ° C. in a hydrogen chloride gas atmosphere. The treatment is performed for 5 to 5 hours, preferably 0.5 to 2 hours.

Sintering step Next, in the method for producing the transparent silica glass of the present invention, the molded body degreased (purified as necessary) as described above is heated at 1,400 to 1,800 ° C. for 1 to 60 minutes, Transparent silica glass is produced by sintering. The sintering conditions of the silica-containing organopolysiloxane resin composition of the present invention after degreasing are not particularly limited, but are usually 1,400 to 1 in an atmosphere of an inert gas such as helium gas or nitrogen gas. , 800 ° C., preferably 1,500 to 1,800 ° C. When the temperature is lower than 1,400 ° C., sintering due to fusion of silica does not proceed and devitrification occurs. Above 1,800 ° C., crystallization of silica is promoted and devitrification occurs. The sintering time can be 1 minute to 60 minutes, preferably about 1 to 30 minutes. If it is less than 1 minute, the silicas are not sufficiently fused and devitrified. If it exceeds 60 minutes, crystallization of the silica is further promoted, resulting in devitrification.

Inspection process In the method for producing the transparent silica glass of the present invention, a transparent film having a thickness of 1 mm is measured by the method described in JIS K 7105: 1981 in order to measure the transparency from the ultraviolet region to the visible region as an inspection step after the sintering step. A step of measuring the transmittance of silica glass can be added. The transmittance for light having a wavelength in the range of 250 to 300 nm is preferably 90% or more, and more preferably 92 to 100%. Such light transmittance can be suitably used as a lens material for UV having good luminance. By selecting the transparent silica glass having light transmittance in the above range by the inspection step, only a high-purity and highly transparent transparent glass molded body can be obtained.

  With such a method for producing a transparent silica glass of the present invention, organic groups can be reduced as much as possible by using an organopolysiloxane composition as a binder, and therefore degreasing for burning carbon components in the binder. Since the time required for the process can be shortened and the reaction proceeds at a high temperature, the binder becomes silica. Therefore, unlike conventional binders, volume shrinkage during degreasing and sintering can be reduced to the limit. Therefore, there is no fear of voids and cracks, and the above highly transparent and highly accurate transparent silica glass can be easily produced.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following formulae, Me is a methyl group, Vi is a vinyl group, and Ph is a phenyl group.

The material used by the Example and comparative example of this invention is shown.
(A) Spherical silica particles The spherical silica particles described in Table 1 below were used.
As the average particle diameter, the value of the volume average diameter measured by a laser diffraction particle size distribution analyzer (“Microtrac HRA (X-100)” manufactured by Nikkiso Co., Ltd.) was used.

  As the aspect ratio, the ratio of the major axis (D) to the minor axis (d) obtained by image analysis software (WINROOF2015, manufactured by Mitani Sangyo Co., Ltd.) and the value of D / d were used.

  The amount of metal impurities was measured by ICP-OES (730-ES ICP-OES manufactured by Agilent). After dissolving 0.3 g of a sample with hydrofluoric acid and nitric acid, the solution is heated to dryness, 0.5 mL of concentrated nitric acid and an appropriate amount of water are added to the dried product, and the mixture is heated and concentrated, and again to 2 mL with water. The solution was measured at a constant volume. From the obtained measured values, the amounts of Al, Fe and Na were quantified by the absolute calibration curve method.

アドマファインＳＯ−Ｅ５、ＳＯ−Ｅ５高純度品、ＳＯ−Ｃ５：アドマテックス（株）製
ＥＭＩＸ−１００：（株）龍森製
ＧＢ−ＡＣ：マコー（株）製
ＭＫＣシリカ：日本化成（株）製

Admafine SO-E5, SO-E5 high-purity product, SO-C5: EMIX-100 manufactured by Admatechs Co., Ltd .: GB-AC manufactured by Tatsumori Co., Ltd .: MKC silica manufactured by Macau Co., Ltd .: Nippon Kasei Co., Ltd. Made

For the alkenyl group-containing organopolysiloxane (B1),
Alkenylorganopolysiloxane A
(SiO _4/2 ) unit 45 mol%,
(Me ₃ SiO _1/2 ) unit 40 mol%
(Me ₂ ViSiO _1/2 ) Unit 15 mol%
Vinyl group equivalent 0.10 mol / 100 g
Alkenylorganopolysiloxane B
(PhSiO _3/2 ) Unit 70 mol%
(Me ₂ ViSiO _1/2 ) Unit 30 mol%
Vinyl group equivalent 0.20 mol / 100 g
Alkenylorganopolysiloxane C
(Me ₂ SiO _2/2 ) Unit 90 mol%
(Me ₂ ViSiO _1/2 ) Unit 10 mol%
Vinyl group equivalent 0.13 mol / 100 g
Alkenylorganopolysiloxane D
(Me ₂ SiO _2/2 ) Unit 95 mol%
(Me ₂ ViSiO _1/2 ) Unit 5 mol%
Vinyl group equivalent 0.067 mol / 100 g
Alkenylorganopolysiloxane E
(MePhSiO _2/2 ) Unit 90 mol%
(Me ₂ ViSiO _1/2 ) Unit 10 mol%
Vinyl group equivalent 0.076mol / 100g
Alkenylorganopolysiloxane F
(Me ₂ SiO _2/2 ) Unit 63 mol%
(Ph ₂ SiO _2/2 ) Unit 30 mol%
(Me ₂ ViSiO _1/2 ) Unit 7 mol%
Vinyl group equivalent 0.059 mol / 100 g
It was used.

(B2) For hydrogen organopolysiloxane,
Hydrogen Organopolysiloxane A
(MeHSiO _2/2 ) Unit 75 mol%
(Me ₃ SiO _1/2 ) Unit 25 mol%
Hydrosilyl group equivalent 0.0114 mol / g
Hydrogen Organopolysiloxane B
(MeHSiO _2/2 ) Unit 95 mol%
(Me ₃ SiO _1/2 ) Unit 5 mol%
Hydrosilyl group equivalent 0.0155 mol / g
Hydrogen Organopolysiloxane C
(MeHSiO _2/2 ) Unit 67 mol%
(Ph ₂ SiO _2/2 ) Unit 30 mol%
(Me ₃ SiO _1/2 ) Unit 3 mol%
Hydrosilyl group equivalent 0.00652 mol / g
Hydrogen Organopolysiloxane D
(Me ₂ HSiO _1/2 ) Unit 50 mol%
(Ph ₂ SiO _2/2 ) Unit 50 mol%
Hydrosilyl group equivalent 0.00402 mol / g
Hydrogen Organopolysiloxane E
(Me ₂ HSiO _1/2 ) Unit 67 mol%
(PhSiO _3/2 ) Unit 33 mol%
Hydrosilyl group equivalent 0.00759 mol / g
It was used.

  As the hydrosilylation reaction catalyst (B3), a vinyl silicone-modified solution of chloroplatinic acid (platinum concentration 1 mass%) was used.

  In addition to these, a 50 mass% toluene solution of ethynylcyclohexanol was used as a reaction inhibitor.

(Preparation Examples 1-8, Comparative Preparation Examples 1-4)
First, an organopolysiloxane composition was prepared using a planetary mixer with the formulation shown in Table 2 below. The prepared organopolysiloxane composition was evaluated for the following blending characteristics, and the results are shown in Table 2.

[Refractive index]
The refractive index (nD ²³ ) of the sample at 23 ° C. was measured according to JIS K 0062: 1992.

[viscosity]
The viscosity at 23 ° C. of the sample was measured with a rotational viscometer in accordance with JIS K 7117-1: 1999.

[Remaining rate]
After weighing 10 mg of sample with a TGA device (TA Instruments Q500), raising the temperature rising rate from 25 ° C. to 1,000 ° C. at a rate of 20 ° C./min and holding at 1,000 ° C. for 30 minutes The sample mass was measured, and the residual rate was determined by the following formula.

(Comparative Preparation Example 5)
Instead of the organopolysiloxane composition (B), 8 g of methyl cellulose (trade name: Metroles SM-4000, manufactured by Shin-Etsu Chemical Co., Ltd.) and 92 g of water were added and mixed with a planetary mixer to prepare a methyl cellulose binder composition. .

(Comparative Preparation Example 6)
In place of the organopolysiloxane composition (B), 8 g of polyvinyl alcohol (PVA) and 92 g of pure water were added and mixed for 1 minute at 2,000 rpm using a rotating and rotating mixer, then for 1 minute at 2,200 rpm, A PVA binder composition was prepared.

(Examples 1-15, Comparative Examples 1-11)
The organopolysiloxane composition or binder composition prepared in Preparation Examples 1-8 and Comparative Preparation Examples 1-6 and each silica particle were mixed, and the following characteristics were measured. The results are shown in Tables 3 and 4.

[Formability]
The composition after mixing the silica particles is poured into a 30 × 30 × 1 mm mold and molded by heating at 80 ° C. for 5 minutes at a molding pressure of 0.5 MPa using a compression molding machine (manufactured by TOWA). The formed product was checked for flow marks, unfilled and cracks.

[Transmissivity]
The sample molded under the same conditions as the moldability evaluation was degreased by heating at 1,000 ° C. for 2 hours, and then heated at 1,650 ° C. for 10 minutes using a firing furnace (VESTA manufactured by Shimadzu Access Corp.) Sintered. The sintered sample was measured for transmittance in a light having a wavelength in the range of 200 to 800 nm with an ultraviolet-visible light spectrophotometer (U-4100, manufactured by Hitachi Technosystem) at a scanning speed of 300 nm / min, and the wavelength was 250 nm. And a light transmittance of 300 nm was evaluated. When the sintered product was cracked and could not be measured, it was described as “not measurable”.

[appearance]
About the sample after sintering used by evaluation of the transmittance | permeability, the external appearance was evaluated visually and color tone, transparency, the presence or absence of a crack, etc. were evaluated. When it was colorless and transparent and there was no crack, it was described as “colorless and transparent”, and when there was something abnormal, Tables 3 and 4 were described.

[Amount of impurities after sintering]
The amount of metal impurities after sintering was measured by ICP-OES (Agilent 730-ES ICP-OES). After dissolving 0.3 g of a sample with hydrofluoric acid and nitric acid, the solution is heated to dryness, 0.5 mL of concentrated nitric acid and an appropriate amount of water are added to the dried product, and the mixture is heated and concentrated, and again to 2 mL with water. The solution was measured at a constant volume. From the obtained measured values, the amounts of Al, Fe and Na were quantified by the absolute calibration curve method. The results are shown in Tables 3 and 4.

  As shown in Table 3, the transparent silica glass produced in Examples 1 to 15 had good moldability, was free from dullness, was highly transparent, and could be easily produced.

  As shown in Tables 2 and 4, in Comparative Examples 1 to 7, the viscosity of which exceeds 10,000 mPa · s, the resin and silica do not exist densely during sintering, so the transmittance is low and the moldability is very high The cracks and unfilling occurred. Moreover, the transmittance | permeability was low in the comparative example 8 which used methylcellulose, and the comparative examples 9-11 which used PVA.

  From the above, it has been clarified that according to the present invention, a highly transparent transparent silica glass without such dullness can be easily produced.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

Claims (9)

The following (A) component and (B) component;
(A) Spherical silica particles having an average particle diameter of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) The refractive index at 23 ° C. is 1. An organopolysiloxane composition having a viscosity of 40 to 1.55 and a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s and containing a hydrosilylation reaction catalyst: baking of a composition containing 0.1 to 20 parts by mass A transparent silica glass characterized by being a ligated body. The component (B) is the following component (B1), component (B2), and component (B3);
(B1) Organopolysiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule (B2) Organopolysiloxane having a hydrogen atom bonded to two or more silicon atoms in one molecule: (B1 ) An amount such that the total number of hydrogen atoms bonded to silicon atoms in the component (B2) is 0.5 to 8.0 with respect to the total number of alkenyl groups in the component (B3) Hydrosilylation reaction catalyst: catalyst The transparent silica glass according to claim 1, which is an organopolysiloxane composition containing an amount. The components (B1) to (B3) are
(B1) The following formula (1)

(In the formula, R ¹ is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, two or more of R ¹ are alkenyl groups having 2 to 10 carbon atoms, and a is 0 to 0.7. B is 0 to 0.9, c is 0 to 0.99, and d is 0.05 to 0.7, provided that a + b + c + d = 1.0.
(B2) The following average composition formula (2)

(In the formula, R ² is independently a group selected from a monovalent saturated hydrocarbon group having 1 to 7 carbon atoms and an aromatic hydrocarbon group having 6 to 7 carbon atoms, and e is 0.6 to 2.0. , F is a positive number of 0.4 to 1.0, where e + f = 1.0 to 2.5.)
The transparent silica glass according to claim 2, which is a hydrogen organopolysiloxane having a hydrogen atom bonded to two or more silicon atoms in one molecule (B3) a platinum group metal catalyst. .   The component (B) has a residual rate of 40% or more in TGA analysis measured by the method described in JIS K 7120: 1987 at a maximum temperature of 1,000 ° C. in air. The transparent silica glass according to any one of claims 1 to 3. The following (A) component and (B) component;
(A) Spherical silica particles having an average particle diameter of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) The refractive index at 23 ° C. is 1. Organopolysiloxane composition having a viscosity of 40 to 1.55 and a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s and containing a hydrosilylation reaction catalyst: A composition containing 0.1 to 20 parts by mass is prepared. After the step of forming, the step of forming the composition to form a molded body, then the step of heating the molded body at 400 to 1,200 ° C. for 10 minutes to 12 hours to degrease, and the degreased molding A method for producing a transparent silica glass, comprising a step of heating and sintering a body at 1,400 to 1,800 ° C. for 1 to 60 minutes. As the component (B), the following component (B1), component (B2), and component (B3);
(B1) Organopolysiloxane having an alkenyl group bonded to two or more silicon atoms in one molecule (B2) Organopolysiloxane having a hydrogen atom bonded to two or more silicon atoms in one molecule: (B1 ) An amount such that the total number of hydrogen atoms bonded to silicon atoms in the component (B2) is 0.5 to 8.0 with respect to the total number of alkenyl groups in the component (B3) Hydrosilylation reaction catalyst: catalyst 6. The method for producing a transparent silica glass according to claim 5, wherein an organopolysiloxane composition containing the amount is used. As the components (B1) to (B3),
(B1) The following formula (1)

(In the formula, R ¹ is independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, two or more of R ¹ are alkenyl groups having 2 to 10 carbon atoms, and a is 0 to 0.7. B is 0 to 0.9, c is 0 to 0.99, and d is 0.05 to 0.7, provided that a + b + c + d = 1.0.
(B2) The following average composition formula (2)

(In the formula, R ² is independently a group selected from a monovalent saturated hydrocarbon group having 1 to 7 carbon atoms and an aromatic hydrocarbon group having 6 to 7 carbon atoms, and e is 0.6 to 2.0. , F is a positive number of 0.4 to 1.0, where e + f = 1.0 to 2.5.)
The transparent organosilica glass according to claim 6, wherein a hydrogen organopolysiloxane (B3) platinum group metal catalyst having a hydrogen atom bonded to two or more silicon atoms in one molecule is used. Manufacturing method.   6. The step of heating and purifying the compact at 1,000 to 1,500 ° C. for 0.5 to 5 hours in a hydrogen chloride gas atmosphere before the sintering step. The manufacturing method of the transparent silica glass as described in any one of Claim 7 from.   The component (B) is a component having a residual rate of 40% or more in TGA analysis measured by the method described in JIS K 7120: 1987 at a maximum temperature of 1,000 ° C. in air. The manufacturing method of the transparent silica glass as described in any one of Claims 5-8.