JP6831754B2 - Transparent silica glass and its manufacturing method - Google Patents

Description

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

At present, the white LED market is expanding greatly, and high heat resistance and high impact resistance of resins are required as the brightness of chips is increased. Currently, silicone is mainly used for high brightness LEDs.

Recently, UV LEDs have been developed for sterilization applications. Since UV LEDs mainly emit light in a wavelength region of 400 nm, extremely high heat resistance, impact resistance, and discoloration resistance are required. However, silicone is decomposed in the UV region, and problems such as cracks and discoloration are occurring.

Therefore, at present, most of the LED structures have a glass or the like hermetically sealed with a reflector directly above the UV LED chip without adding an organic component. However, when it comes to glass that absorbs less short wavelengths, there is only quartz glass, which is very expensive, and the glass structure can only be a flat plate structure, and a wide variety of lens structures and Fresnel structures can be used. It was difficult to install.

Conventionally, a glass sintered body produced by molding a kneaded product of an inorganic powder and a binder and sintering it has been known, but it has been difficult to obtain a high-purity and highly transparent molded product (). Patent Document 1). Further, a method has been found in which a transparent silica glass is produced by molding with a cellulose derivative such as methyl cellulose or methyl hydroxyethyl cellulose (Patent Documents 2 and 3) or polyvinyl alcohol (PVA) (Patent Document 4) and sintering the mixture. There is. However, when the cellulose derivative is used as a binder, the moldability is good, but impurities in the cellulose derivative remain and it is difficult to exhibit high transparency. Further, when PVA is used as a binder as well, there is a problem in transparency after sintering due to the inclusion of a plasticizer of PVA as an impurity, and it is often difficult to mass-produce it. Further, conventionally, a method of sintering a silica-containing gel whose pH has been adjusted by a sol-gel method has been known (Patent Documents 5 and 6), but the procedure of this production method is complicated.

Japanese Unexamined Patent Publication No. 2008-266087 JP-A-2009-120444 Japanese Unexamined Patent Publication No. 2013-525156 JP-A-2009-007185 Japanese Patent Publication No. 2011-530468 Special Table 2010-502554

Therefore, in view of the above circumstances, it is an object of the present invention to provide a transparent silica glass having high purity and high transparency. Another object of the present invention is to provide a manufacturing method capable of efficiently mass-producing high-purity and highly transparent transparent silica glass.

In order to solve the above problems, the present invention
The following components (A) and (B);
(A) Spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) One or more hydrosilyl groups and 1 Organosilicon-based binder having 0 or more alkoxysilyl groups: A transparent silica glass which is a sintered body of a composition containing 0.1 to 20 parts by mass is provided.

A transparent silica glass as in the present invention is a highly pure and highly transparent transparent silica glass.

（式中、Ｒは炭素数１〜１０の１価の有機基であり、Ｘはヒドロキシ基又は炭素数１〜１０のアルコキシ基であり、Ｘのうち、１つ以上はアルコキシ基であり、ｘ及びｙは、それぞれ０＜ｘ≦１、０≦ｙ≦３であり、かつ０＜ｘ＋ｙ＜４である。）
で示される有機ケイ素化合物、
（Ｂ２）下記式（２）

（式中、Ｒ’は独立して水素原子又は前記Ｒで示される基であり、Ｒ’のうち、１つ以上は水素原子であり、Ｘは前記と同じであり、Ｘのうち、１つ以上はアルコキシ基であり、ａは０〜０．７、ｂは０〜０．９、ｃは０．０１〜０．９９、ｄは０〜０．５０、ｅは０．００１〜０．２５であり、但しａ＋ｂ＋ｃ＋ｄ＋ｅ＝１．０である。）
で示されるオルガノポリシロキサン、
から選ばれる１種以上の化合物を含むものであることが好ましい。 At this time, the component (B) is the following component (B1) and component (B2);
(B1) The following formula (1)

(In the formula, R is a monovalent organic group having 1 to 10 carbon atoms, X is a hydroxy group or an alkoxy group having 1 to 10 carbon atoms, and one or more of X is an alkoxy group, and x And Y are 0 <x ≦ 1 and 0 ≦ y ≦ 3, respectively, and 0 <x + y <4).
Organosilicon compound, indicated by
(B2) The following formula (2)

(In the formula, R'is an independent hydrogen atom or a group represented by the above R, one or more of R'is a hydrogen atom, X is the same as above, and one of X is The above are alkoxy groups, a is 0 to 0.7, b is 0 to 0.9, c is 0.01 to 0.99, d is 0 to 0.50, and e is 0.001 to 0.25. However, a + b + c + d + e = 1.0.)
Organopolysiloxane, indicated by
It is preferable that the compound contains one or more compounds selected from the above.

Such a component (B) is suitable as a binder and becomes a transparent silica glass having more excellent transparency.

Further, it is preferable that the component (B) contains one or more silicon atoms having one or more hydrogen atoms and one or more alkoxy groups having 1 to 10 carbon atoms in one molecule.

With such a component (B), a transparent silica glass without voids or cracks can be obtained more reliably and easily.

Further, the viscosity of the component (B) at 23 ° C. is preferably 0.1 to 10,000 mPa · s.

With such a component (B), a transparent silica glass is obtained in which voids are not likely to be generated during degreasing or sintering.

At this time, the component (B) contains at least the component (B2), and the component (B2) has a maximum temperature of 1,000 ° C. in the air and is measured by the method described in JIS K 7120: 1987. It is preferable that the residual ratio in the analysis is 40% or more.

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

Further, in the present invention, the following components (A) and (B);
(A) Spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) One or more hydrosilyl groups and 1 Organic silicon-based binder having two or more alkoxysilyl groups: After the step of preparing a composition containing 0.1 to 20 parts by mass, the step of molding the composition to form a molded product, and then the molded product. Is heated at 400 to 1,200 ° C. for 10 minutes to 12 hours to degrease, and further comprises a step of heating the degreased molded product at 1,400 to 1,800 ° C. for 1 to 60 minutes and sintering. A method for producing transparent silica glass is provided.

With the production method as in the present invention, high-purity and highly transparent transparent silica glass can be efficiently mass-produced.

（式中、Ｒは炭素数１〜１０の１価の有機基であり、Ｘはヒドロキシ基又は炭素数１〜１０のアルコキシ基であり、Ｘのうち、１つ以上はアルコキシ基であり、ｘ及びｙは、それぞれ０＜ｘ≦１、０≦ｙ≦３であり、かつ０＜ｘ＋ｙ＜４である。）
で示される有機ケイ素化合物、
（Ｂ２）下記式（２）

（式中、Ｒ’は独立して水素原子又は前記Ｒで示される基であり、Ｒ’のうち、１つ以上は水素原子であり、Ｘは前記と同じであり、Ｘのうち、１つ以上はアルコキシ基であり、ａは０〜０．７、ｂは０〜０．９、ｃは０．０１〜０．９９、ｄは０〜０．５０、ｅは０．００１〜０．２５であり、但しａ＋ｂ＋ｃ＋ｄ＋ｅ＝１．０である。）
で示されるオルガノポリシロキサン、
から選ばれる１種以上の化合物を含むものを用いることが好ましい。 At this time, as the component (B), the following component (B1) and component (B2);
(B1) The following formula (1)

(In the formula, R is a monovalent organic group having 1 to 10 carbon atoms, X is a hydroxy group or an alkoxy group having 1 to 10 carbon atoms, and one or more of X is an alkoxy group, and x And Y are 0 <x ≦ 1 and 0 ≦ y ≦ 3, respectively, and 0 <x + y <4).
Organosilicon compound, indicated by
(B2) The following formula (2)

(In the formula, R'is an independent hydrogen atom or a group represented by the above R, one or more of R'is a hydrogen atom, X is the same as above, and one of X is The above are alkoxy groups, a is 0 to 0.7, b is 0 to 0.9, c is 0.01 to 0.99, d is 0 to 0.50, and e is 0.001 to 0.25. However, a + b + c + d + e = 1.0.)
Organopolysiloxane, indicated by
It is preferable to use one containing one or more compounds selected from the above.

With such a production method using the component (B), transparent silica glass having more excellent transparency can be easily produced.

Further, as the component (B), it is preferable to use an organosilicon binder containing at least one silicon atom having one or more hydrogen atoms and one or more alkoxy groups having 1 to 10 carbon atoms in one molecule.

With such a production method using the component (B), high-quality transparent silica glass without voids or cracks can be easily produced more reliably.

Further, as the component (B), it is preferable to use a component having a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s.

With such a production method using the component (B), transparent silica glass in which the generation of voids during degreasing and sintering is suppressed can be easily produced.

Further, at this time, it is preferable to include a step of heating the formed body at 1,000 to 1,500 ° C. for 0.5 to 5 hours to purify the formed product in a hydrogen chloride gas atmosphere before the sintering step.

With the manufacturing method including the purification step as described above, it is possible to manufacture transparent silica glass in which the occurrence of devitrification is further suppressed by removing impurities that may cause devitrification during sintering.

Further, in the TGA analysis, the component (B) contains at least the component (B2), and the component (B2) has a maximum temperature of 1,000 ° C. in the air and is measured by the method described in JIS K 7120: 1987. It is preferable to use one having a residual ratio of 40% or more.

If the production method uses the component (B), there is no risk of large voids being generated between the silicas during degreasing and sintering of the composition, and there is no risk of cracks or devitrification after sintering. Silica glass can be easily produced.

As described above, in the case of the transparent silica glass of the present invention, by using an organic silicon-based binder (silane or condensed siloxane) having a composition similar to that of silica as a binder, the affinity with silica is enhanced and cracks, voids and dullness are enhanced. Can be suppressed and high transparency can be achieved. Furthermore, since impurities that cause devitrification that remain on the order of ppm can be reduced as much as possible, high purity can be achieved. In addition, the alkoxy group and silanol group contained in the binder promote the bond with silica, degreasing, and the formation of a chemical bond during sintering, so that the transparency is very high and the transmittance is excellent at a wide wavelength. It becomes transparent silica glass. Further, in the method for producing transparent silica glass of the present invention, by using an organic silicon-based binder as a binder, discoloration after degreasing and sintering can be reduced to the utmost, and the number of organic groups can be reduced as much as possible. Since the binder becomes silica as the reaction proceeds at a high temperature, the volume shrinkage during degreasing and sintering can be reduced to the utmost, unlike the conventional binder. Further, since the catalyst caused by the binder and unnecessary elements can be reduced, high-quality transparent silica glass can be produced inexpensively and easily, and the process can be rationalized at the time of mass production.

As described above, there has been a demand for the development of high-purity and highly transparent transparent silica glass and a manufacturing method capable of efficiently mass-producing such transparent silica glass.

As a result of diligent studies to achieve the above object, the present inventors have found that by using an organosilicon-based binder as a binder, high-purity and highly transparent transparent silica glass can be produced inexpensively and easily. Completed the invention.

That is, the present invention describes the following components (A) and (B);
(A) Spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) One or more hydrosilyl groups and 1 Organosilicon-based binder having 10 or more alkoxysilyl groups: A transparent silica glass which is a sintered body of a composition containing 0.1 to 20 parts by mass.

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 size in the range of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50. The average particle size is preferably 0.05 to 100 μm, more preferably 0.1 to 10 μm. In the present invention, the average particle size of the spherical silica particles refers to the value of the volume average diameter of the particles measured by the dynamic light scattering method. The aspect ratio of the spherical silica particles is preferably 1.00 to 1.40, more preferably 1.00 to 1.20. In the present invention, the aspect ratio is a value measured as the ratio of the major axis (D) to the minor axis (d), that is, D / d, by an image taken by SEM.

In addition, the spherical silica particles used in the present invention are more spherical than those produced from natural silica, such as aluminum, sodium, and iron, which are synthesized by the sol-gel method or hydrolysis of chlorosilane and by metal removal purification. It is preferable to use silica particles in which the amount of impurities often contained is reduced to the utmost limit. In the present invention, the amount of impurities refers to the element content measured by an inductively coupled plasma emission spectrophotometer (ICP-OES) and quantified by an absolute calibration curve method. The aluminum content in the spherical silica particles is preferably 0.1 to 50 ppm, more preferably 0.1 to 10 ppm. The smaller the aluminum content, the better, but considering the cost, it is sufficient to remove up to 0.1 ppm, and if it is 50 ppm or less, the progress of crystallization of silica during sintering, which causes devitrification. Can be suppressed. 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, but in consideration of cost and the like, it is sufficient to remove up 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 smaller the iron content, the better, but in consideration of cost and the like, it is sufficient to remove 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 and crystalline silica such as stishovite and cristobalite, and quartz.

The content of the component (A) is 80 to 99.9 parts by mass, preferably 85 to 99.5 parts by mass, and more preferably 90 to 99.5 parts by mass in 100 parts by mass of the composition for a sintered body. is there.

(B) Organosilicon Binder The organosilicon binder used as the component (B) of the present invention closely binds the spherical silica particles of the component (A) to each other to reduce voids during sintering as much as possible. It is to be added to. The component (B) has one or more hydrosilyl groups and one or more alkoxysilyl groups, and preferably has one or more hydrogen atoms and one or more alkoxy groups having 1 to 10 carbon atoms. Is contained in one molecule or more.

Further, in the present invention, the viscosity of the component (B) is a value at 23 ° C. measured by a rotational viscometer described in JIS K 7117-1: 1999, preferably 0.1 to 10,000 mPa · s. It is more preferably 1 to 8,000 mPa · s, and even more preferably 1 to 1,000 mPa · s. Within this range, the component (B) blends neatly into the silica surface when the spherical silica particles of the component (A) are highly filled, and almost no voids are formed during degreasing or sintering, which is preferable.

（式中、Ｒは炭素数１〜１０の１価の有機基であり、Ｘはヒドロキシ基又は炭素数１〜１０のアルコキシ基であり、Ｘのうち、１つ以上はアルコキシ基であり、ｘ及びｙは、それぞれ０＜ｘ≦１、０≦ｙ≦３の正数であり、かつ０＜ｘ＋ｙ＜４である。）
で示される有機ケイ素化合物、
（Ｂ２）下記式（２）

（式中、Ｒ’は独立して水素原子又は前記Ｒで示される基であり、Ｒ’のうち、１つ以上は水素原子であり、Ｘは前記と同じであり、Ｘのうち、１つ以上はアルコキシ基であり、ａは０〜０．７、ｂは０〜０．９、ｃは０．０１〜０．９９、ｄは０〜０．５０、ｅは０．００１〜０．２５であり、但しａ＋ｂ＋ｃ＋ｄ＋ｅ＝１．０である。）
で示されるオルガノポリシロキサン、
から選ばれる１種以上の化合物を含むものであることが好ましい。 The component (B) used in the present invention includes the following component (B1) and component (B2);
(B1) The following formula (1)

(In the formula, R is a monovalent organic group having 1 to 10 carbon atoms, X is a hydroxy group or an alkoxy group having 1 to 10 carbon atoms, and one or more of X is an alkoxy group, and x And y are positive numbers of 0 <x ≦ 1 and 0 ≦ y ≦ 3, respectively, and 0 <x + y <4.)
Organosilicon compound, indicated by
(B2) The following formula (2)

(In the formula, R'is an independent hydrogen atom or a group represented by the above R, one or more of R'is a hydrogen atom, X is the same as above, and one of X is The above are alkoxy groups, a is 0 to 0.7, b is 0 to 0.9, c is 0.01 to 0.99, d is 0 to 0.50, and e is 0.001 to 0.25. However, a + b + c + d + e = 1.0.)
Organopolysiloxane, indicated by
It is preferable that the compound contains one or more compounds selected from the above.

The component (B1) and the component (B2) both have one or more hydrosilyl groups and one or more alkoxysilyl groups, and preferably 1 to 100 hydrosilyl groups and 1 to 100 alkoxysilyl groups, respectively. Each has 1 to 20 pieces. Further, the component (B1) and the component (B2) may be used alone or in combination, but it is preferable that the component (B2) is contained at least.

In the present invention, the component (B) contains at least the component (B2), and the component (B2) remains in the TGA analysis measured by the method described in JIS K 7120: 1987 at a maximum temperature of 1,000 ° C. in the air. The fraction is preferably 40% or more, and more preferably the residual ratio is 40 to 60%. When the residual ratio is 40% or more, the generation of large voids between spherical silica particles can be suppressed during degreasing and sintering of the composition, and the generation of cracks and devitrification after sintering can be suppressed.

The residual ratio in the present invention is, for example, a TGA device (Q500 manufactured by TA Instruments), weighing 10 mg of a sample, and raising the temperature from 25 ° C. to 1,000 ° C. at a heating rate of 20 ° C./min. After holding the sample at 1,000 ° C. for 30 minutes, the sample mass can be measured and calculated by the following formula.

The content of the component (B) is 0.1 to 20 parts by mass, preferably 0.1 to 10 parts by mass, and 0.1 to 5 parts by mass in 100 parts by mass of the composition for a sintered body. Is more preferable. Each of them will be described in detail below in order.

で示される有機ケイ素化合物（オルガノハイドロジェンシラン）である。 (B1) Organosilicon compound The component (B1) used in the present invention has the following formula (1).

It is an organosilicon compound (organohydrogensilane) represented by.

In the above formula, R is a monovalent organic group having 1 to 10 carbon atoms and is not an alkoxy group. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert- Alkyl group such as butyl group, pentyl group, neopentyl group, hexyl group, octyl group, nonyl group, decyl group, cycloalkyl group such as cyclopentyl group and cyclohexyl group, phenyl group, trill group, xylyl group, naphthyl group and other aryl Aralkyl group such as group, benzyl group, phenylethyl group, phenylpropyl group, alkenyl group such as vinyl group and allyl group, 2- (3,4 epoxycyclohexyl) ethyl group, 3-glycidoxypropyl group, 3-methacyl Roxypropyl group, N-2 (aminoethyl) γ-aminopropyl group, 3-aminopropyl group, N-phenyl-3-aminopropyl group, 3-mercaptopropyl group, 2-cyanoethyl group, 3-cyanopropyl group, Examples include a carbinol group.

In the above formula, X is a hydroxy group or an alkoxy group having 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms, and preferred examples thereof include a hydroxy group, a methoxy group, an ethoxy group, a propyl group and an isopropyl group. Further, one or more of X are alkoxy groups.

x is 0 <x ≦ 1.0, preferably 0 <x ≦ 0.5, and more preferably 0 <x ≦ 0.3. y is 0 ≦ y ≦ 3, preferably 0 to 2.0, and more preferably 0 to 1.5. It should be noted that 0 <x + y <4.

Specific examples of the organic silicon compound as the component (B1) include trialkoxysilanes such as trimethoxysilane and triethoxysilane, alkylalkoxysilanes such as methyldimethoxysilane and methyldiethoxysilane, and 3-mercaptopropylmethyldimethoxysilane. Examples thereof include alkoxysilane compounds, preferably trimethoxysilane, triethoxysilane, and methyldiethoxysilane. In addition, these alkoxysilanes may be used alone or in mixture of 2 or more types. Moreover, it is not limited to these.

で示されるオルガノポリシロキサンである。 (B2) Organopolysiloxane The component (B2) used in the present invention is the following formula (2).

It is an organopolysiloxane represented by.

In the above formula, R'is an independent hydrogen atom or a group represented by the above R, and one or more of R'is a hydrogen atom. X is the same as described above, and one or more of X are alkoxy groups. Examples of R'and X include the same groups as those mentioned in the component (B1). a is 0 to 0.7, preferably 0 to 0.65, and more preferably 0 to 0.60. b is 0 to 0.9, more preferably 0 to 0.80, still more preferably 0 to 0.75. c is 0.01 to 0.99, preferably 0.01 to 0.98, and more preferably 0.2 to 0.95. d is 0 to 0.50, preferably 0 to 0.3, and more preferably 0 to 0.25. e is 0.001 to 0.25, preferably 0.01 to 0.25, and more preferably 0.15 to 0.25. However, a + b + c + d + e = 1.0.

Component (B2) is a linear, branched, cyclic, and may have any of the network structure, R _'3 SiO _1/2 units (M units), R' ₂ SiO _2/2 units (D units ), R'SiO _3/2 unit (T unit), and SiO _4/2 unit (Q unit), but always includes the D unit. When the component (B2) is used, the component (B) cannot be assumed to have 0.1 to 10,000 mPa · s at 23 ° C. unless it has a D unit. Further, it is preferable to have an alkoxy group bonded to a silicon atom because the condensation reaction between the components (B) proceeds smoothly. In particular, silicone oil which is composed of D unit and M unit and has a linear structure (continuous D unit) is preferable. This silicone oil may contain Q units. Further, the component (B2) may be a partially hydrolyzed condensate of the alkoxysilane of the component (B1). In this case, partially hydrolyzed condensates such as methyltrimethoxysilane, trimethoxysilane, triethoxysilane, methyldiethoxysilane, and 3-glycidoxypropyltrimethoxysilane are preferred.

(C) Organosilicon-based binder other than the component (B) The composition for a sintered body used in the present invention contains an organosilicon-based binder other than the component (B) as the component (C), if necessary. You can also do it. Examples of the component (C) include tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, and methyltriethoxysilane. Alkylalkoxysilanes such as n-propyltriethoxysilane, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, 1,6-bis (trimethoxysilyl) hexane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, Arylalkoxysilanes such as diphenyldimethyldimethoxysilane, diphenyldimethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, p-styryltrimethoxysilane, hydroxytrialkoxysilane, hydroxytrimethoxysilane, hydroxytriethoxysilane and the like, 2 Carbinol group-containing silanes such as −hydroxyethyltrimethoxysilane, 3-hydroxypropyltriethoxysilane, 3- (2-hydroxyethyl) propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxy Epyl group-containing alkoxysilanes such as propylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N- 2- (Aminoethyl) 3-Aminopropyltrimethoxysilane, N-2- (Aminoethyl) 3-Aminopropylmethyldimethoxysilane, 3-Aminopropyltrimethoxysilane, 3-Aminopropyltriethoxysilane, N-phenyl- Amino group-containing alkoxysilanes such as 3-aminopropyltrimethoxysilane, 3-allylaminopropyltrimethoxysilane, N- (N-vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane, 3-isocyanate Propyl triethoxysilane, isocyanate alkoxysilane such as tris- (trimethoxysilylpropyl) isocyanurate, cyano group-containing silane such as 2-cyanoethyltrimethoxysilane, 3-cyanopropyltriethoxysilane, 3-ureidopropyltriethoxysilane, 3-Mercaptopropyltrimethoxysilane, Bis (Trisue Examples thereof include an alkoxysilane compound such as toxisilylpropyl) tetrasulfide, and preferably tetramethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. In addition, these alkoxysilanes may be used by 1 type or a mixture of 2 or more types. Moreover, it is not limited to these.

When the component (C) is added, the organosilicon binder composition in which the component (B) and the component (C) are mixed has a preferable viscosity range, a preferable residual ratio, and a preferable content of the component (B) described above. It is preferable to satisfy the amount and the like.

The transparent silica glass of the present invention is a sintered body of such a composition (composition for a sintered body). In the case of such transparent silica glass of the present invention, by using an organic silicon-based binder having a composition close to that of silica as a binder, the affinity with silica is enhanced, the occurrence of cracks, voids and dullness is suppressed, and high transparency is achieved. It can be realized. Furthermore, since impurities that cause devitrification that remain on the order of ppm can be reduced as much as possible, high purity can be achieved. In addition, the alkoxy group and silanol group contained in the binder promote the bond with silica, degreasing, and the formation of a chemical bond during sintering, so that the transparency is very high and the transmittance is excellent at a wide wavelength. It becomes transparent silica glass.

<Manufacturing method of transparent silica glass>
Further, in the present invention, the following components (A) and (B);
(A) Spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) One or more hydrosilyl groups and 1 Organic silicon-based binder having two or more alkoxysilyl groups: After the step of preparing a composition containing 0.1 to 20 parts by mass, the step of molding the composition to form a molded product, and then the molded product. Is heated at 400 to 1,200 ° C. for 10 minutes to 12 hours to degrease, and further comprises a step of heating the degreased molded product at 1,400 to 1,800 ° C. for 1 to 60 minutes and sintering. A method for producing transparent silica glass is provided. Hereinafter, each step will be described in detail.

Composition Preparation Method In the method for producing transparent silica glass of the present invention, first, a composition (composition for a sintered body) containing the component (A) and the component (B) is prepared. As the component (A) and the component (B), the same components as those mentioned in the above description of the transparent silica glass can be used. Further, the above-mentioned component (C) (that is, an organosilicon binder other than the component (B)) may be added to this composition. The composition can be prepared by stirring, dissolving, mixing and dispersing each of the above-mentioned components simultaneously or separately with heat treatment if necessary, but usually, the component (B1) and the component (B2) are prepared. It is preferable that the components, and if necessary, the component (C) are first mixed to prepare an organosilicon binder composition, and then mixed with the spherical silica particles (A).

The device used for operations such as stirring when mixing the spherical silica particles (A) with the prepared organosilicon binder composition is not particularly limited, but a Raikai machine equipped with a stirring and heating device, three rolls, a ball mill, and a planeta. A Lee mixer, a rotating / revolving mixer, or the like can be used. Moreover, you may combine these devices as appropriate.

Molding Step In the method for producing transparent silica glass of the present invention, the composition for a sintered body prepared as described above is then molded to form a molded product. The molding method is not particularly limited, and it may be molded into a desired shape by a known method.

Solventing Step In the method for producing transparent silica glass of the present invention, the molded product formed as described above is then heated at 400 to 1,200 ° C. for 10 minutes to 12 hours to degreas. The carbon component of the sintered body composition is gradually removed by degreasing. Without the degreasing step, the carbon component remaining at the time of sintering will be carbonized, which will cause devitrification. The degreasing step is performed 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 in an atmosphere other than hydrogen chloride gas, for example, helium gas or nitrogen gas. To do. If the temperature is lower than 400 ° C., degreasing does not proceed sufficiently and degreasing occurs during sintering. If the temperature exceeds 1,200 ° C., silica crystallizes and devitrifies.

Purification Step In the method for producing transparent silica glass of the present invention, a purification step which is a step of removing Al, Na, Fe and the like may be incorporated before the sintering step. When the purification step is performed, 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 carried out under the conditions of 5 to 5 hours, preferably 0.5 to 2 hours.

Sintering Step In the method for producing transparent silica glass of the present invention, the molded product degreased (purified if necessary) as described above is then 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 composition of the present invention after degreasing are not particularly limited, but are usually 1,400 to 1,800 ° C., preferably 1,400 to 1,800 ° C. under an atmosphere of an inert gas such as helium gas or nitrogen gas. It can be sintered at 1,500 to 1,800 ° C. If 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 is 1 minute to 60 minutes, preferably about 1 to 30 minutes. If it is less than 1 minute, the silicas will not be sufficiently fused and will be devitrified. If it exceeds 60 minutes, the crystallization of silica is further promoted and the silica is devitrified.

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

In such a method for producing transparent silica glass of the present invention, by using an organic silicon-based binder as a binder, discoloration after degreasing and sintering can be reduced to the utmost, and the number of organic groups can be reduced as much as possible. Since the binder becomes silica as the reaction proceeds at a high temperature, the volume shrinkage during degreasing and sintering can be reduced to the utmost, unlike the conventional binder. Further, since the catalyst caused by the binder and unnecessary elements can be reduced, high-quality transparent silica glass can be produced inexpensively and easily, and the process can be rationalized at the time of mass production.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Further, in the following formula, Me is a methyl group and Ph is a phenyl group.

The materials used in the Examples and Comparative Examples of the present invention are shown.
(A) Spherical silica particles As the spherical silica particles, those listed in Table 1 below were used.
For the average particle size, the value of the volume average diameter by a laser diffraction type particle size distribution measuring device (“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 of the SEM image taken by the SEM 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 the 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 then reconstituted with water to 2 mL. The volume was adjusted and a measurement solution was prepared. 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: Admatex Co., Ltd. EMIX-100: Ryumori Co., Ltd. GB-AC: Macau Co., Ltd. MKC silica: Nihon Kasei Co., Ltd. Made

As the organosilicon compound of (B1), the following compounds were used.
Organosilicon compound A: Trimethoxysilane (KBM-03 manufactured by Shin-Etsu Chemical Co., Ltd.)
Organosilicon compound B: Methyldiethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

(B2) As the organopolysiloxane, the following was used.
Organopolysiloxane A:
(HSiO _3/2 ) _0.926 (OMe) _0.056 (OH) _0.018

As the organosilicon binder other than the components (C) and (B), the following ones were used. In the following, the abbreviation "GP" represents a 3-glycidoxypropyl group, and the abbreviation "AP" represents a 3-aminopropyl group.
Organosilicon binder A other than the component (B):
3-glycidoxypropyltrimethoxysilane (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.)
Organosilicon binder B other than the component (B):
2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane (KBM-303 manufactured by Shin-Etsu Chemical Co., Ltd.)
Organosilicon binder C other than the component (B):
Diphenyldimethoxysilane (KBM-202 manufactured by Shin-Etsu Chemical Co., Ltd.)
Organosilicon binder D other than the component (B):
3-Aminopropyltrimethoxysilane (KBM-903 manufactured by Shin-Etsu Chemical Co., Ltd.)
Organosilicon binders other than the component (B) E:
(Me ₂ SiO _2/2 ) _0.833 (OH) _0.167
Organosilicon binder F other than the component (B):
(Me ₂ SiO _3/2 ) _0.546 (Me ₂ SiO _2/2 ) _0.364 (OMe) _0.04 (OH) _0.06
Organosilicon binder G other than the component (B):
(Ph ₂ SiO _2/2 ) _0.50 [Me ₂ (HO) Si _1/2 ] _0.50
Organosilicon binder H other than the component (B):
(GPSiO _3/2 ) _0.901 (OMe) _0.036 (OH) _0.063
Organosilicon binder I other than the component (B):
(APSiO _3/2 ) _0.926 (OMe) _0.037 (OH) _0.037
Organosilicon binder J: other than the component (B)
(Me ₂ SiO _2/2 ) _0.996 [Me ₂ (HO) Si _1/2 ] _0.004
Organosilicon binder K other than the component (B):
(Ph ₂ SiO _2/2 ) _0.50 (Me ₃ SiO _1/2 ) _0.50

(Preparation Examples 1 to 8, Comparative Preparation Examples 1 to 5)
First, an organosilicon binder composition was prepared using a planetary mixer with the formulation shown in Table 2 below. In addition, the prepared organosilicon binder composition was evaluated for the following compounding characteristics, and the results are shown in Table 2.

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

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

(Comparative Preparation Example 6)
Instead of the organosilicon binder (B), 8 g of methyl cellulose (trade name: Metrose 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 7)
8 g of polyvinyl alcohol (PVA) and 92 g of pure water were added instead of the organosilicon binder (B), and the mixture was mixed at 2,000 rpm for 1 minute using a rotation / revolution mixer, and then at 2,200 rpm for 1 minute, and then PVA. A binder composition was prepared.

(Examples 1 to 15, Comparative Examples 1 to 11)
Each silica particle was mixed with the organosilicon-based binder composition or other binder composition prepared in Preparation Examples 1 to 8 and Comparative Preparation Examples 1 to 7, and the following characteristics were measured. The results are shown in Tables 3 and 4.

[Moldability]
The composition after mixing the silica particles is injected into a mold of 30 × 30 × 1 mm, and molded by heating at 80 ° C. × 5 minutes at a molding pressure of 0.5 MPa using a compression molding machine (manufactured by TOWA Corporation). It was confirmed whether or not the flow mark, unfilled and cracks were generated in the molded product.

[Transmittance]
A sample molded under the same conditions as the evaluation of moldability 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 Co., Ltd.). Sintered. For the sample after sintering, the transmittance of light in the wavelength range of 200 to 800 nm was measured with an ultraviolet visible light spectrophotometer (U-4100 manufactured by Hitachi Techno System Co., Ltd.) at a scanning speed of 300 nm / min, and the wavelength was 250 nm. And the light transmittance at 300 nm was evaluated. If the sintered product cracked and could not be measured, it was described as "not measurable".

[appearance]
The appearance of the sintered sample used in the evaluation of the transmittance was visually evaluated, and the color tone, transparency, presence or absence of cracks, etc. were evaluated. If it is colorless and transparent and has no cracks, it is described as "colorless and transparent", and if there is any abnormality, it is described in Tables 3 and 4.

[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 the 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 then reconstituted with water to 2 mL. The volume was adjusted and a measurement solution was prepared. 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 glasses produced in Examples 1 to 15 had good moldability, no dullness, high transparency and high purity, and could be easily produced.

As shown in Tables 2 and 4, in Comparative Examples 1 to 8 in which a compound containing either or both of an alkoxy group and a hydrosilyl group was used as the organosilicon binder, cracks and uncured during molding occurred. The moldability was very poor, and cracks occurred because the binder and silica were not densely present at the time of sintering. Further, Comparative Example 9 in which methyl cellulose was used instead of the component (B) and Comparative Example 10 in which PVA was used had many impurities, and Comparative Example 11 had a low transmittance.

From the above, it has been clarified that according to the present invention, high-purity and highly transparent transparent silica glass can be easily produced.

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any object having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect and effect is the present invention. Is included in the technical scope of.

Claims (9)

The following components (A) and (B);
(A) Spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) One or more hydrosilyl groups and 1 Organosilicon-based binder having 0 or more alkoxysilyl groups: A transparent silica glass which is a sintered body of a composition containing 0.1 to 20 parts by mass.
The component (B) is the following component (B1) and component (B2);
(B1) The following formula (1)

(In the formula, R is a monovalent organic group having 1 to 10 carbon atoms, X is a hydroxy group or an alkoxy group having 1 to 10 carbon atoms, and one or more of X is an alkoxy group, and x And Y are 0 <x ≦ 1 and 0 ≦ y ≦ 3, respectively, and 0 <x + y <4).
Organosilicon compound, indicated by
(B2) The following formula (2)

(In the formula, R'is an independent hydrogen atom or a group represented by the above R, one or more of R'is a hydrogen atom, X is the same as above, and one of X is The above are alkoxy groups, a is 0 to 0.7, b is 0 to 0.9, c is 0.01 to 0.99, d is 0 to 0.50, and e is 0.001 to 0.25. However, a + b + c + d + e = 1.0.)
Organopolysiloxane, indicated by
A transparent silica glass characterized by containing. The transparency according to claim 1, wherein the component (B) contains one or more silicon atoms having one or more hydrogen atoms and one or more alkoxy groups having 1 to 10 carbon atoms in one molecule. Silica glass. The transparent silica glass according to claim 1 or 2, wherein the viscosity of the component (B) at 23 ° C. is 0.1 to 10,000 mPa · s. The residue in the TGA analysis measured by the method described in JIS K 7120: 1987 when the component (B) contains at least the component (B2) and the component (B2) has a maximum temperature of 1,000 ° C. in air. The transparent silica glass according to any one of claims 1 to 3, wherein the ratio is 40% or more. The following components (A) and (B);
(A) Spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 80 to 99.9 parts by mass (B) One or more hydrosilyl groups and 1 Organic silicon-based binder having two or more alkoxysilyl groups: After the step of preparing a composition containing 0.1 to 20 parts by mass, the step of molding the composition to form a molded product, and then the molded product. Is heated at 400 to 1,200 ° C. for 10 minutes to 12 hours to degrease, and further comprises a step of heating the degreased molded product at 1,400 to 1,800 ° C. for 1 to 60 minutes and sintering. A method for manufacturing transparent silica glass.
As the component (B), the following component (B1) and component (B2);
(B1) The following formula (1)

(In the formula, R is a monovalent organic group having 1 to 10 carbon atoms, X is a hydroxy group or an alkoxy group having 1 to 10 carbon atoms, and one or more of X is an alkoxy group, and x And Y are 0 <x ≦ 1 and 0 ≦ y ≦ 3, respectively, and 0 <x + y <4).
Organosilicon compound, indicated by
(B2) The following formula (2)

(In the formula, R'is an independent hydrogen atom or a group represented by the above R, one or more of R'is a hydrogen atom, X is the same as above, and one of X is The above are alkoxy groups, a is 0 to 0.7, b is 0 to 0.9, c is 0.01 to 0.99, d is 0 to 0.50, and e is 0.001 to 0.25. However, a + b + c + d + e = 1.0.)
Organopolysiloxane, indicated by
A method for producing transparent silica glass, which comprises using one containing. The claim is characterized in that, as the component (B), an organosilicon-based binder containing at least one silicon atom having one or more hydrogen atoms and one or more alkoxy groups having 1 to 10 carbon atoms in one molecule is used. 5. The method for producing transparent silica glass according to 5. The method for producing transparent silica glass according to claim 5 or 6, wherein as the component (B), a component having a viscosity at 23 ° C. of 0.1 to 10,000 mPa · s is used. 5. The claim 5 comprises a step of heating the molded product at 1,000 to 1,500 ° C. for 0.5 to 5 hours to purify the molded product in a hydrogen chloride gas atmosphere before the sintering step. The method for producing transparent silica glass according to any one of claims 7. The (B) component contains at least the (B2) component, and the (B2) component has a maximum temperature of 1,000 ° C. in the air and is a residue in the TGA analysis measured by the method described in JIS K 7120: 1987. The method for producing transparent silica glass according to any one of claims 5 to 8, wherein a glass having a rate of 40% or more is used.