JP7316248B2 - COMPOSITION FOR TRANSPARENT SILICA GLASS AND METHOD FOR PRODUCING TRANSPARENT SILICA GLASS - Google Patents

Description

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

In the LED market in recent years, as chips have become brighter and higher in output, silicone resins for encapsulating them have been required to have extremely high heat resistance, impact resistance, and light resistance.

In addition to visible light LEDs, IR-LEDs used as in-vehicle sensors and UV-LEDs used for sterilization and the like are being developed. In particular, UV-LEDs have a short wavelength of 300 nm or less as a main peak emission wavelength, so even if the output of the LED is small, the silicone resin encapsulant that absorbs at this wavelength will deteriorate. Therefore, there is a problem that the silicone resin cannot satisfy discoloration resistance, impact resistance, and the like.

Therefore, at present, most LED structures are hermetically sealed with glass or the like directly above the UV-LED chip with the reflector. However, quartz glass, which is very expensive, is the only glass with low absorption in the short wavelength region. In addition, due to the high processing cost of quartz glass, only a flat glass structure can be produced, and mounting a wide variety of lens structures has inevitably increased the unit price of the package.

Conventionally, there has been known a ceramic sintered body produced by molding and sintering a kneaded product of inorganic powder and a silicone resin as a binder (Patent Document 1). Glass-ceramics with high strength and low thermal expansion have also been developed, but it has been difficult to obtain highly transparent moldings (Patent Document 2).
Also, a transparent quartz glass sintered body is obtained by curing a molded body of quartz glass particles using (meth)acrylate as an organic binder with ultraviolet rays (Patent Document 3), and silica surface-modified with a radically polymerizable group. A casting sol using particles, a polymerization initiator, and a solvent is molded by a casting method, and after curing with ultraviolet rays, a sintered body is obtained (Patent Document 4).
However, these methods are not suitable for producing lens materials that require high dimensional accuracy. In particular, in a system containing a solvent, a large number of voids were generated from the molded body during molding or sintering, and a highly transparent lens could not be produced.

U.S. Pat. No. 3,361,583 JP 2018-177582 A Japanese Patent Publication No. 2019-529322 Japanese Patent Publication No. 2019-534228

Therefore, in view of the above circumstances, an object of the present invention is to provide a composition that becomes transparent silica glass even at short wavelengths, and a transparent silica glass obtained from the composition. Another object of the present invention is to provide a manufacturing method capable of efficiently mass-producing highly transparent silica glass with high dimensional accuracy.

In order to solve the above problems, in the present invention, the following components (A) and (B):
(A) amorphous spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 85 to 99.9 parts by mass;
(B) a silicone binder containing an organopolysiloxane having two or more photopolymerizable reactive groups in one molecule: 0.1 to 15 parts by mass (however, the total of the components (A) and (B) is 100 mass part.),
Provided is a composition for transparent silica glass, characterized by comprising:

Thus, the composition for transparent silica glass of the present invention provides silica glass that is transparent even at short wavelengths.

Further, in the present invention, the component (B) is represented by the following formula (1):
(SiO ₂ ) _a (RSiO _3/2 ) _b (R ₂ SiO) _c (R ₃ SiO _1/2 ) _d X _e (1)
(Wherein, R is independently a hydrogen atom, or an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a (meth) acrylic group having 3 to 10 carbon atoms a group selected from a group selected from a maleimide group having 4 to 20 carbon atoms and an epoxy group having 6 to 15 carbon atoms, and at least two groups in one molecule are either a (meth)acrylic group, a maleimide group, or an epoxy group. A photopolymerizable reactive group, X is a hydroxyl group or an alkoxy group having 1 to 10 carbon atoms, a is 0 to 0.3, b is 0 to 0.3, and c is 0 to 0.9. , d is 0.05 to 1.0, e is 0 to 0.25, provided that a+b+c+d+e=1.0.)
It preferably contains an organopolysiloxane represented by.

When the component (B) contains the organopolysiloxane, molding can be performed in a particularly short time, and silica glass with excellent transparency can be obtained.

Further, in the present invention, it is preferable that (C) a photopolymerization catalyst: 0.1 to 10 parts by mass per 100 parts by mass of component (B) is further included.

If such a (C) component is included, silica glass can be obtained more efficiently.

Further, the present invention can provide a transparent silica glass which is a sintered body of the composition for transparent silica glass.

By sintering the above composition for transparent silica glass, it becomes a transparent silica glass excellent in transparency even to short-wavelength light, and is suitable for lens materials and the like that require high dimensional accuracy.

Further, in the present invention, there is provided a method for producing transparent silica glass, comprising:
(A) amorphous spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 85 to 99.9 parts by mass;
(B) a silicone binder containing an organopolysiloxane having two or more photopolymerizable reactive groups in one molecule: 0.1 to 15 parts by mass (however, the total of the components (A) and (B) is 100 mass part.),
A step of irradiating ^a transparent silica glass composition containing
a step of heating the molded body at 400 to 1,200° C. for 10 minutes to 72 hours to degrease;
and heating the degreased compact at 1,400 to 1,800° C. for 1 minute to 10 hours to produce a sintered body.

With such a production method, since no solvent is used, the generation of voids can be reduced, and the transparent silica glass composition can be molded in a short time. Transparent silica glass can be produced without generating voids or cracks.

As described above, the composition for transparent silica glass of the present invention enables molding in a short time by using a silicone binder containing an organopolysiloxane having two or more photopolymerizable reactive groups in one molecule. When degreased, all of the silicone becomes silica, and the affinity between the amorphous spherical silica particles and silicone is very good, and cracks, voids, devitrification, and crystal formation are suppressed. It becomes sintered silica glass.

Further, according to the method for producing transparent silica glass of the present invention, since molding can be performed at a high density, the inside of the system becomes dense and the occurrence of cracks can be suppressed. In addition, if high-purity silica is used, the transparency of the composition can be maintained even if the particle size is not special, which contributes to the reduction of production costs. Since the silica composition itself is transparent, the irradiation energy can be reduced and the deep-part curability can be improved, ensuring high dimensional accuracy and shortening the time required for mass production and streamlining the number of steps.

As described above, there has been a demand for the development of a composition that becomes transparent silica glass even at short wavelengths, a transparent silica glass obtained from the composition, and a method for producing the same.

The inventors of the present invention have made intensive studies on the above problems, and found that if a silicone binder containing an organopolysiloxane having two or more photopolymerizable reactive groups in one molecule is used, molding can be performed in a shorter time than thermosetting molding. It can be molded into various shapes, and when silicone is degreased, it is all converted to silica, so it is possible to mass-produce silica glass with excellent transparency without discoloration due to residual organic groups. rice field.

That is, the present invention provides the following components (A) and (B):
(A) amorphous spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 85 to 99.9 parts by mass;
(B) a silicone binder containing an organopolysiloxane having two or more photopolymerizable reactive groups in one molecule: 0.1 to 15 parts by mass (however, the total of the components (A) and (B) is 100 mass part.),
A composition for transparent silica glass, characterized by comprising:

Although the present invention will be described in detail below, the present invention is not limited thereto.

<Composition for transparent silica glass>
[(A) Amorphous spherical silica particles]
The amorphous 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 size is preferably 0.05-100 μm, more preferably 0.1-10 μm. In the present invention, the average particle diameter of the amorphous spherical silica particles refers to the value of the volume average particle diameter measured by the dynamic light scattering method. Also, the aspect ratio of the amorphous 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 the ratio of the major axis (D) to the minor axis (d) in an SEM image, that is, a value measured as D/d.

In addition, the amorphous spherical silica particles used in the present invention are synthesized by the sol-gel method or hydrolysis of chlorosilane, and are purified by removing metals such as aluminum, sodium, and iron, rather than those produced from natural silica. It is preferable to use particles in which the amount of impurities often contained in amorphous spherical silica particles, such as, is reduced to the limit. In the present invention, the amount of impurities is measured by an inductively coupled plasma-optical emission spectrometer (ICP-OES) and refers to the elemental content quantified by the absolute calibration curve method. The aluminum content in the amorphous spherical silica particles is preferably 0.1-50 ppm, more preferably 0.1-10 ppm. The lower the aluminum content, the better, but considering the cost etc., it is sufficient if it can be removed to 0.1 ppm, and if it is 50 ppm or less, the crystallization of silica during sintering that causes devitrification progresses. can be suppressed. The sodium content in the amorphous spherical silica particles is preferably 0.01-1 ppm, more preferably 0.05-1 ppm. The lower the sodium content, the better. However, taking cost into consideration, it is sufficient if the sodium content can be removed to 0.01 ppm. Further, the iron content in the amorphous spherical silica particles is preferably 0.1-5 ppm, more preferably 0.1-2 ppm. The lower the iron content, the better. However, considering the cost and the like, it is sufficient if the iron content can be removed to 0.1 ppm. It goes without saying that amorphous spherical silica particles having an impurity amount outside the above range can be used depending on the purpose.

Types of amorphous spherical silica include natural silica, synthetic silica, silica balloons, mesoporous silica, silica gel, and quartz. Synthetic silica is preferred in terms of cost and amount of impurities.

The content of component (A) is 85 to 99.9 parts by mass, preferably 90 to 99.5 parts by mass, more preferably 90 to 99.5 parts by mass, based on the total 100 parts by mass of component (A) and component (B) described later. is 90 to 99 parts by mass.

[(B) Photopolymerizable silicone binder]
The (B) photopolymerizable silicone binder of the present invention is mixed with the amorphous spherical silica of the component (A) to impart moldability to the component (A). By curing the silicone binder, it can be molded into a desired shape.

The component (B) is characterized by containing an organopolysiloxane having two or more photopolymerizable reactive groups in one molecule, and the photopolymerizable reactive groups include acrylic groups, methacrylic groups, maleimide groups, and epoxy groups. At least one selected is preferable. Among them, (C) an organopolysiloxane having a (meth)acrylic group that reacts with a photopolymerization catalyst to be cured is preferred. In particular, the following formula (1)
(SiO ₂ ) _a (RSiO _3/2 ) _b (R ₂ SiO) _c (R ₃ SiO _1/2 ) _d X _e (1)
(Wherein, R is independently a hydrogen atom, or an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a (meth) acrylic group having 3 to 10 carbon atoms a group selected from a group selected from a maleimide group having 4 to 20 carbon atoms and an epoxy group having 6 to 15 carbon atoms, and at least two groups in one molecule are either a (meth)acrylic group, a maleimide group, or an epoxy group. A photopolymerizable reactive group, X is a hydroxyl group or an alkoxy group having 1 to 10 carbon atoms, a is 0 to 0.3, b is 0 to 0.3, and c is 0 to 0.9. , d is 0.05 to 1.0, e is 0 to 0.25, provided that a+b+c+d+e=1.0.)
It preferably contains an organopolysiloxane represented by.

In the present invention, since the component (B) is a silicone binder containing an organopolysiloxane having two or more photopolymerizable reactive groups in one molecule, it can be molded in a short time when photocured, and is suitable for mass production. Excellent silica glass can be obtained.

In the above formula (1), examples of alkyl groups having 1 to 20 carbon atoms for R include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, and neopentyl group. , a hexyl group, an octyl group, a nonyl group, and a decyl group; and a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group. Examples of aryl groups having 6 to 10 carbon atoms include aryl groups such as phenyl, tolyl, xylyl and naphthyl groups; aralkyl groups such as benzyl, phenylethyl and phenylpropyl groups. Among them, a methyl group and a phenyl group are preferred. Examples of alkenyl groups having 2 to 10 carbon atoms include vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, octenyl group and the like. Examples of meth)acryl groups include (meth)acryl groups, methyl (meth)acryl groups, ethyl (meth)acryl groups, n-propyl (meth)acryl groups, isopropyl (meth)acryl groups, n-butyl (meth)acryl groups, ) acrylic group, isobutyl (meth) acrylic group, n-hexyl (meth) acrylic group, cyclohexyl (meth) acrylic group, isobutyl cyclohexyl (meth) acrylic group, 2-ethylhexyl (meth) acrylic group, acetoxyethyl (meth) acrylic phenyl(meth)acryl group, 2-hydroxyethyl(meth)acryl group, 2-methoxyethyl(meth)acryl group, 2-ethoxyethyl(meth)acryl group and the like. Among them, a (meth)acryl group is preferred. Examples of maleimide groups having 4 to 20 carbon atoms include maleimide group, methylmaleimide group, n-propylmaleimide group, isopropylmaleimide group, n-butylmaleimide group, n-hexylmaleimide group, n-octylmaleimide group and the like. . Examples of epoxy groups having 6 to 15 carbon atoms include γ-glycidoxy, β-(3,4-epoxycyclohexyl)ethyl, monoglycidiglycidyl, diglycidylisocyanurate, and oxetanyl. At least two groups in one molecule are preferably photopolymerizable reactive groups of any one of (meth)acrylic groups, maleimide groups and epoxy groups.

[(C) Photopolymerization catalyst]
The photopolymerization catalyst of the component (C) is capable of generating radicals upon exposure to light, and is blended in the composition of the present invention as required. Examples include α-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2-hydroxy-2-methyl-1-(4-isopropylphenyl)propanone, and 2-hydroxy-2 -methyl-1-[(2-hydroxyethoxy)phenyl]propanone, benzophenone, 2-methylbenzophenone, 4-methoxybenzophenone, 2-ethoxycarbonylbenzophenone and the like.

When the photopolymerization catalyst (C) is added, the amount is preferably 0.1 to 10 parts by weight per 100 parts by weight of the component (B). If it is within this range, the sensitivity becomes high by ultraviolet irradiation, and the deep-part curability improves. More preferably, it is in the range of 0.5 to 5 parts by mass per 100 parts by mass of component (B). Two or more photopolymerization catalysts may be used in combination.

The photopolymerization catalyst (C) is preferably used in combination with an acylphosphine compound as a photoinitiator. Specifically, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyl ethoxyphenylphosphine oxide, 2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide, benzoyldi-(2,6-dimethylphenyl)phosphonate and the like.

When the component (C) and the photoinitiator are used in combination, the amount of the photoinitiator is preferably 5 to 50 parts by mass per 100 parts by mass of the component (C).

A compound that serves as a photoinitiator often contains an aromatic compound or a polar group in its molecule in order to efficiently absorb light, and has high crystallinity. Therefore, when mixing the (C) photopolymerization catalyst with the (B) silicone binder, the (C) photopolymerization catalyst and the photoinitiator are dissolved and homogenized in advance at 50 to 150 ° C., and the resulting liquid mixture is preferably added to (B) the organopolysiloxane used in the silicone binder. The obtained mixture of (B) and (C) can be mixed with (A) silica particles to obtain a composition for transparent silica glass.

<Method for producing transparent silica glass>
Transparent silica glass is obtained by curing a composition for transparent silica glass by irradiating it with ultraviolet rays to obtain a molded body, then degreasing and, if necessary, purifying, followed by sintering to obtain transparent silica glass.

1. Molding step This is a step of photopolymerizing the composition for transparent silica glass to produce a molded body. As a method for molding the composition for transparent silica glass, the above composition is applied to a transparent mold and irradiated with ultraviolet rays using, for example, a high-pressure mercury lamp, a xenon lamp, or an ultraviolet light emitting diode as a light source to cure and mold the composition. There is a way to let In addition, if oxygen or the like exists in the air, it acts as a polymerization inhibitor, so curing is preferably performed under an inert gas such as nitrogen or argon. The irradiation energy is 400 to 10,000 mJ/cm ² , preferably 400 to 5,000 mJ/cm ² . Although the wavelength for irradiation is not particularly limited, it is preferably 400 nm or less.

2. Degreasing process The degreasing process is a process of heating component (B) to decompose organic matter and convert it to silica. In the method for producing transparent silica glass of the present invention, next, the molded body produced as described above is heated at 400 to 1,200° C. for 10 minutes to 72 hours to degrease it. The carbon component is gradually removed from the composition for transparent silica glass by degreasing. Without the degreasing step, the carbon component remaining during sintering will be carbonized, causing devitrification. In the degreasing step, the molded body is preferably heated in an atmosphere other than hydrogen chloride gas, such as helium gas, nitrogen gas or air, at a temperature of 400 to 1,200° C., preferably 500 to 1,000° C., for 10 minutes to 72 minutes. hours, preferably 1-6 hours. If the heating temperature is less than 400° C., degreasing does not proceed sufficiently, and devitrification occurs during sintering. If the heating temperature exceeds 1,200° C., crystallization of silica proceeds and devitrification also occurs.

3. Purification Step In the method for producing transparent silica glass of the present invention, a purification step for removing Al, Na, Fe and the like may be incorporated before the sintering step. When performing the purification step, the heating temperature is preferably 1,000 to 1,500° C., more preferably 1,000 to 1,300° C., still more preferably 1,100 to 1,100° C., for example, in a hydrogen chloride gas atmosphere. The treatment is performed at 300° C. for preferably 0.5 to 5 hours, more preferably 0.5 to 2 hours. By performing this treatment, amorphous spherical silica particles containing a large amount of Al, Na, Fe, etc. as impurities can be effectively used. If the amorphous spherical silica particles used as component (A) have high purity, this purification step may not necessarily be performed.

4. Sintering Step In the method for producing transparent silica glass of the present invention, next, the molded body degreased (purified if necessary) as described above is heated at 1,400 to 1,800° C. for 1 minute to 10 hours. , to produce transparent silica glass by sintering. Although the sintering conditions for the transparent silica glass molded body of the present invention after degreasing are not particularly limited, it is usually 1,400 to 1,400 in an atmosphere of an inert gas such as helium gas, argon gas, or nitrogen gas. It can be sintered at 1,800°C, preferably 1,500-1,800°C. If the temperature is lower than 1,400° C., sintering due to fusion between silica particles does not proceed, resulting in devitrification. At temperatures higher than 1,800° C., crystallization of silica is accelerated and devitrification occurs. The sintering time is 1 minute to 10 hours, preferably 1 minute to 1 hour. If the sintering time is less than 1 minute, the silica particles will not be sufficiently fused with good reproducibility, and devitrification may occur. When the sintering time exceeds 10 hours, crystallization of silica is further accelerated, resulting in devitrification.

According to the method for producing transparent silica glass of the present invention, since the photopolymerizable silicone is used as the binder, the molding time can be greatly shortened, and the carbon content in the binder is lower than that of conventional organic binders. Combined with this, the time required for the degreasing process to burn the carbon component in the binder can be shortened, and the binder becomes silica as the reaction progresses at high temperatures, unlike conventional organic binders. Shrinkage and cracks during sintering are suppressed.

EXAMPLES The present invention will be specifically described below using Examples and Comparative Examples, but the present invention is not limited to these.

[Amorphous spherical silica particles]
As the amorphous spherical silica particles, those shown in Table 1 below were used. Crushed silica was used as the synthetic quartz powder.
As the average particle diameter, the value of the volume average diameter measured by a laser diffraction particle size distribution analyzer ("Microtrac HR (X-100)" manufactured by Nikkiso Co., Ltd.) was used.

As the aspect ratio, the ratio of the diameter (D) to the short diameter (d) obtained by using image analysis software (WINROOF2015, manufactured by Mitani Sangyo Co., Ltd.), which is the value of D/d, was 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, 0.35 mL of concentrated nitric acid and an appropriate amount of water are added to the dry matter, heated and concentrated, and the volume is adjusted to 2 mL again with water. A solution for measurement was prepared. From the measured values obtained, the amounts of Al, Fe, and Na were quantified by the absolute calibration curve method.

アドマファインＳＯ－Ｅ５，アドマファイン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（破砕状シリカ）

ADMAFINE SO-E5, ADMAFINE SO-C5: Admatechs Co., Ltd. EMIX-100: Tatsumori Co., Ltd. GB-AC: Maco Co., Ltd. MKC Silica: Nippon Kasei Co., Ltd. (crushed silica )

[Photopolymerizable silicone binder]
The silicone binders (organopolysiloxanes A to C) having two or more photopolymerizable reactive groups per molecule used as component (B) were synthesized according to the following synthesis examples.

[Synthesis Example 1]
198.3 g (1.0 mol) of phenyltrimethoxysilane and 438.7 g (4.0 mol) of acryldimethylsilanol were added, and 13.3 g (0.05 mol) of strontium hydroxide octahydrate was added. After reacting for 8 hours, an organopolysiloxane A having a molecular weight of 540 represented by the chemical formula (2) was obtained.

[Synthesis Example 2]
219.4 g (2.0 mol) of acryldimethylsilanol was reacted at an internal temperature of 40° C. for 8 hours to obtain an organopolysiloxane B having a molecular weight of 270 represented by the chemical formula (3).

[Synthesis Example 3]
g (1 mol) of diphenyldimethoxysilane and 219.4 g (3.0 mol) of acryldimethylsilanol are added, 10.6 g (0.04 mol) of strontium hydroxide octahydrate is added and reacted at an internal temperature of 10°C for 8 hours, Methanol was distilled off to obtain an organopolysiloxane C having a molecular weight of 470 represented by the chemical formula (4).

化学式（６）で示されるオルガノポリシロキサンＥ、

オルガノシロキサンＦとして、
３－メタクリロキシプロピルトリメトキシシラン（ＫＢＭ－５０３ 信越化学工業（株）製）
を使用した。 In addition, for organopolysiloxanes D, E and organosiloxane F,
Organopolysiloxane D represented by the chemical formula (5),

Organopolysiloxane E represented by the chemical formula (6),

As organosiloxane F,
3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.)
It was used.

(C) As for the photopolymerization catalyst, photopolymerization catalyst: 2-hydroxy-2-methyl-1-phenylpropanone and photoinitiator: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide were used.

(Examples 1 to 7, Comparative Examples 1 to 6)
First, components (A) and (B) are mixed according to the formulation shown in Table 2, and finally component (C) is mixed to prepare a composition for transparent silica glass. The following properties were measured using the composition. Table 2 shows the results.

[Moldability]
The composition obtained by mixing (A) to (C) was poured into a 30 x 30 x 1 mm methyl-based silicone mold and molded using a UV conveyor with an irradiation energy of 800 mJ/cm ² to obtain the shape of the molded product. , confirmed the presence or absence of voids.

[exterior]
A sample molded under the same conditions as the moldability evaluation was degreased by heating at 800° C. for 24 hours, and then heated and sintered at 1750° C. for 10 minutes using a firing furnace (Shimadzu Access Co. VESTA). All samples after sintering had a thickness of 0.8 mm. The appearance of the sample was visually evaluated, and the color tone, transparency, presence or absence of cracks and voids, etc. were evaluated. When it was colorless and transparent and had no cracks or voids, it was described as "colorless and transparent."

As shown in Table 2, the transparent silica glasses produced in Examples 1 to 7 had good moldability, were highly transparent without voids or cracks, and could be easily produced into molded bodies.

When the content of the amorphous spherical silica particles is small as in Comparative Example 1, voids and cracks occur. When the molecule had only one photopolymerizable reactive group as in Comparative Example 2, it did not cure. When an organic photocurable binder other than silicone was used as in Comparative Examples 3 and 4, even if molding could be completed in a short period of time, a dense molded body could not be molded, and cracks occurred after sintering. If the particle size of the amorphous (spherical) silica particles is too large or the aspect ratio is too large as in Comparative Examples 5 and 6, cavities become large and voids during sintering.

From the above, it is clear that with the present invention, a dense molded body can be molded in a short time, and a highly transparent sintered body without cracks or voids even after sintering can be easily produced. became.

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

Claims (3)

Components (A) and (B) below:
(A) amorphous spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 85 to 99.9 parts by mass;
(B) the following formula (1):
(SiO ₂ ) _a (RSiO _3/2 ) _b (R ₂ SiO) _c (R ₃ SiO _1/2 ) _d X _e (1)
(Wherein, R is independently a hydrogen atom, or an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a (meth) acrylic group having 3 to 10 carbon atoms a group selected from a group selected from a maleimide group having 4 to 20 carbon atoms and an epoxy group having 6 to 15 carbon atoms, and at least two groups in one molecule are either a (meth)acrylic group, a maleimide group, or an epoxy group. A photopolymerizable reactive group, X is a hydroxyl group or an alkoxy group having 1 to 10 carbon atoms, a is 0 to 0.3, b is 0 to 0.3, and c is 0 to 0.9. , d is 0.05 to 1.0, e is 0 to 0.25, provided that a+b+c+d+e=1.0.)
Organopolysiloxane represented by: 0.1 to 15 parts by mass (where the total of the components (A) and (B) is 100 parts by mass),
A composition for transparent silica glass, comprising: Furthermore, (C) a photopolymerization catalyst: 0.1 to 10 parts by mass with respect to 100 parts by mass of the component (B),
The composition for transparent silica glass according to claim 1, comprising: A method for producing transparent silica glass, comprising:
(A) amorphous spherical silica particles having an average particle size of 0.01 to 150 μm and an aspect ratio of 1.00 to 1.50: 85 to 99.9 parts by mass;
(B) the following formula (1):
(SiO ₂ ) _a (RSiO _3/2 ) _b (R ₂ SiO) _c (R ₃ SiO _1/2 ) _d X _e (1)
(Wherein, R is independently a hydrogen atom, or an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a (meth) acrylic group having 3 to 10 carbon atoms a group selected from a group selected from a maleimide group having 4 to 20 carbon atoms and an epoxy group having 6 to 15 carbon atoms, and at least two groups in one molecule are either a (meth)acrylic group, a maleimide group, or an epoxy group. A photopolymerizable reactive group, X is a hydroxyl group or an alkoxy group having 1 to 10 carbon atoms, a is 0 to 0.3, b is 0 to 0.3, and c is 0 to 0.9. , d is 0.05 to 1.0, e is 0 to 0.25, provided that a+b+c+d+e=1.0.)
Organopolysiloxane represented by: 0.1 to 15 parts by mass (where the total of the components (A) and (B) is 100 parts by mass),
A step of irradiating ^a transparent silica glass composition containing
a step of heating the molded body at 400 to 1,200° C. for 10 minutes to 72 hours to degrease;
and a process for producing a sintered body by heating the degreased compact at 1,400 to 1,800° C. for 1 minute to 10 hours.