WO2018131668A1 - Quartz glass and ultraviolet emitting element member using same - Google Patents

Abstract

The purpose of the present invention is to provide a quartz glass which has an excellent laser processability or which has wavelength-selective transmission properties and, therefore, is suitably usable for sterilization. The present invention pertains to a quartz glass wherein, when an indentation is formed on the surface of the quartz glass by using a Vickers indenter, a pressing load of the Vickers indenter at which the incidence of cracking is 50% is 0.1-0.5 kgf, or a quartz glass wherein the linear transmittance (%) at a wavelength of 265 nm in terms of a ​​glass thickness of 1 mm is 85% or more and the difference ΔT between the linear transmittance (%) at a wavelength of 230 nm and the linear transmittance (%) at a wavelength of 200 nm is 10-50%.

Description

Quartz glass and ultraviolet light emitting element member using the same

The present invention relates to quartz glass and an ultraviolet light emitting element member using the same. The quartz glass of the present invention is suitable for a window member of an ultraviolet light emitting element such as an ultraviolet light emitting diode (UV-LED).

UV light-emitting elements are used in various applications such as sterilization, disinfection, water purification, air purification, light therapy, plant growth control, sensing, resin curing, analysis, and surface modification. Conventionally, mercury lamps have been frequently used as ultraviolet light-emitting elements, but in recent years, conversion to LEDs (light-emitting diodes) with less environmental impact is being studied.

In the ultraviolet LED (UV-LED), a flat plate or a lens-shaped window member is used at the light emitting portion. The window member functions as a cover member that protects the ultraviolet LED chip, and also has a function of condensing and expanding light emitted from the ultraviolet LED. As a material of the optical lens, for example, synthetic quartz glass having excellent transmission characteristics in a short wavelength region (deep ultraviolet region) having a wavelength of approximately 350 nm or less is used (Patent Document 1). Microbial nucleic acids such as bacteria, fungi, and viruses have an absorption spectrum peak in the vicinity of a wavelength of 265 nm. Therefore, transmission characteristics with a wavelength of 265 nm are important for sterilization applications.
As a method for producing synthetic quartz glass used for the above purpose, a flame hydrolysis method is generally used (Patent Document 2).

For example, a window member made of quartz glass having a thickness of about 0.5 mm and a thickness of about 3.5 to 5 mm square is used for the UV-LED module. In order to obtain such a small piece of quartz glass member, it is necessary to process a synthetic quartz glass ingot obtained by the flame hydrolysis method into a wafer, and further to make a small piece by laser processing, and the productivity is low.
In order to improve productivity, it is extremely difficult to obtain a synthetic quartz glass having a desired shape by casting or pressing because of its high melting point and viscosity.

On the other hand, there is a gel casting method as a manufacturing method for obtaining a ceramic molded body having a desired shape. The gel casting method is a method of casting a slurry containing a ceramic powder, a dispersion medium, and a gelling agent, and then solidifying the slurry by gelation by adding temperature conditions or a crosslinking agent. How to get. Patent Document 3 discloses a method for producing quartz glass by a gel cast method.
According to the gel cast method, it is considered that quartz glass having a wafer shape or an uneven shape can be directly produced, and a UV-LED window member can be obtained by making a small piece by laser processing.

Quartz glass used as a window member of a UV-LED is required to have good laser processability in order to make a desired shape by adding a small piece from a wafer or fine processing.
Known laser processing methods include thermal processing using ultraviolet, visible, and infrared lasers, and non-thermal processing (ablation processing) using a short pulse laser. Non-thermal processing is a more preferable method because the thermal effect on the glass and the occurrence of chipping are suppressed.
When quartz glass is irradiated with a short pulse laser, a modified layer is continuously or intermittently formed inside the glass. After that, heating and thermal expansion by long pulse laser irradiation and cleaving starting from the modified region by applying mechanical stress from outside are performed, but in order to perform high-accuracy cleaving, modification is performed during pulse laser irradiation. It is desirable that fine cracks occur in the region.

Japanese Unexamined Patent Publication No. 2015-179734 Japanese Patent Publication No. 7-33259 Japanese Patent No. 5937839 Specification

From the viewpoint of laser processability, it is desirable that quartz glass used as a window member for UV-LEDs has high absorption in the wavelength region of light used for laser processing. On the other hand, it is desirable that the light transmittance in the wavelength range of the light emitted from the UV-LED is high. That is, it is preferable that there is wavelength selective light transparency.

Also, as described above, the window member mounted on the UV-LED module for sterilization uses an important transmission characteristic at a wavelength of 265 nm. On the other hand, when a light source including high energy light having a wavelength of 230 nm or less that is not necessary for sterilization is used, the peripheral member is locally irradiated with high energy light, which causes member deterioration. That is, it is preferable that there is a wavelength-selective light transmission property that suppresses transmission of high-energy light that causes deterioration of the member while transmitting light having a wavelength of 265 nm that has a high bactericidal effect.

In view of the above circumstances, an object of the present invention is to provide a member for an ultraviolet light emitting element excellent in laser processability and quartz glass used therefor.
Another object of the present invention is to provide a member for an ultraviolet light-emitting device having a wavelength-selective light transmittance suitable for sterilization and a quartz glass used therefor.

In order to achieve the above object, the present invention achieves the above-mentioned object, and the indentation load of the Vickers indenter with a crack occurrence rate of 50% when the indentation is formed on the surface using the Vickers indenter is 0.1 to 0.5 kgf. Provide glass.

The quartz glass of the present invention preferably has a β-OH group concentration of 10 to 800 ppm converted from a Si—OH-derived peak of 2500 to 3900 cm ^{−1 in} the IR spectrum.

The quartz glass of the present invention has a difference ΔT of 10 to 50% between the linear transmittance (%) at a wavelength of 250 nm (in terms of thickness 1 mm) and the linear transmittance (%) at a wavelength of 200 nm (in terms of thickness 1 mm). Is preferred.

In addition, the quartz glass of the present invention preferably has a total light transmittance (%) at a wavelength of 265 nm (in terms of thickness 1 mm) of 85% or more.

The quartz glass of the present invention preferably has a linear transmittance (%) at a wavelength of 265 nm (in terms of thickness 1 mm) of 60% or more.

The quartz glass of the present invention preferably has a total content of Na and K of 10 to 800 ppm.

In the quartz glass of the present invention, the number of scatterers having an average diameter of 1 to 50 μm is preferably 50 to 5000 per cm ² , and the scatterers are selected from the group consisting of holes, crystals and opals. It is preferable that it is at least one kind.

The quartz glass of the present invention has a linear transmittance (%) at a wavelength of 265 nm (converted to a thickness of 1 mm) of 80% or more, and a linear transmittance (%) at a wavelength of 230 nm (converted to a thickness of 1 mm) and a straight line having a wavelength of 200 nm. The difference ΔT from the transmittance (%) (in terms of thickness 1 mm) is preferably 10 to 50%.

The present invention also provides a member for an ultraviolet light emitting element using the quartz glass of the present invention.

The present invention also provides a member for an ultraviolet light emitting element in which the orientation (light distribution) of light is controlled by imparting a shape to the quartz glass of the present invention.

The present invention also provides an ultraviolet light emitting element member in which the quartz glass of the present invention and a bonding agent are integrated.

Further, the present invention provides a member for an ultraviolet light emitting element, in which the quartz glass of the present invention is AR coated.

The quartz glass of the present invention has good laser processability when the quartz glass of a large substrate such as a wafer shape is cut into pieces by laser processing.
Moreover, the quartz glass of the present invention has a wavelength-selective light transmittance suitable for sterilization applications and suppressing deterioration of peripheral members.

Hereinafter, the quartz glass of the present invention will be described. In the present specification, “to” indicating a numerical range is used in a sense including numerical values described before and after the numerical value as a lower limit value and an upper limit value. Further, “parts by mass” and “parts by weight” are synonymous, and when “ppm” is simply described, it means that they are ppm by weight.
The quartz glass of the present invention has a Vickers indenter indentation load (hereinafter referred to as “CIL value”) of 0.1 when the indentation is formed on the surface using a Vickers indenter and the incidence of cracks is 50%. ~ 0.5 kgf. When the indentation load of the Vickers indenter is within the above range, it is excellent in laser processability when the wafer-shaped quartz glass is shredded by laser processing, and can be easily shredded from a large-sized or arrayed product. Excellent.

It is known that internal stress is induced in quartz glass by irradiation with an ultrashort pulse laser, and a high density region called a modified layer is formed. In addition, this internal stress may cause fine cracks in the modified region, which is considered advantageous for high-accuracy cleaving starting from the modified region. The width of the modified layer, which is the starting point of the cleaving observed in the cross-sectional observation, becomes large when the indentation load of the Vickers indenter at which the crack generation rate is 50% is 0.1 to 0.5 kgf. It is considered excellent.

When the CIL value exceeds 0.5 kgf, high energy is required when performing ultrashort pulse laser processing, and an expensive apparatus with high output is required. Further, even if such an apparatus is used, the pulse energy becomes excessive, and there is a possibility that problems such as chipping and shape defects may occur.
On the other hand, when the CIL value is less than 0.1 kgf, when the quartz glass of the present invention is used for a member for an ultraviolet light emitting element, there is a possibility that problems such as being easily damaged when used as a window member of the ultraviolet light emitting element may occur.
Therefore, the CIL value is 0.1 to 0.5 kgf, preferably 0.1 to 0.3 kgf, and more preferably 0.2 to 0.3 kgf.

The quartz glass of the present invention preferably has a β-OH group concentration of 10 to 800 ppm converted from a Si—OH-derived peak of 2500 to 3900 cm ^{−1 in} the IR spectrum.
By setting the β-OH group concentration to 10 ppm or more, when a radical species such as E ′ center or NBOHC is generated due to the breakage of the SiO ₂ bond when irradiated with a high energy laser, the repair action by Si—OH is achieved. This is preferable because it can suppress a change in transmittance due to laser processing. On the other hand, by setting the β-OH group concentration to 800 ppm or less, it is possible to prevent an absorption band having a peak in the vicinity of a wavelength of 170 nm from increasing, and to prevent the absorption edge from affecting the transmittance at a wavelength of 265 nm. preferable.
The β-OH group concentration is more preferably 40 ppm or more, and more preferably 100 ppm or less.

In the quartz glass of the present invention, the difference ΔT between the linear transmittance (%) at a wavelength of 265 nm (in terms of thickness 1 mm) and the linear transmittance (%) at a wavelength of 200 nm (in terms of thickness 1 mm) is preferably 10 to 50%. .
If ΔT is in the above range, the light transmittance in the wavelength range (wavelength 265 nm) of the light emitted from the UV-LED is high, while the wavelength range of light having a wavelength of 200 nm or less, for example, excimer laser, used for high-energy laser processing. This is because the wavelength-selective light transmission property that absorption at a wavelength of 193 nm is better achieved.

The quartz glass of the present invention preferably has a total light transmittance (%) at a wavelength of 265 nm (in terms of 1 mm thickness) of 80% or more, more preferably 85% or more, and further preferably 90% or more. preferable.

The quartz glass of the present invention preferably has a linear transmittance (%) at a wavelength of 265 nm (in terms of thickness of 1 mm) of 60% or more, more preferably 75% or more, and further preferably 80% or more. . When the linear transmittance (%) at a wavelength of 265 nm (in terms of thickness 1 mm) is 60% or more, the influence of scattering is small, and the shape of the window member is changed to a lens type, a dome type, a bullet type, etc. It is preferable because light distribution control by imparting a shape becomes easy.

In the quartz glass of the present invention, the total content of Na and K is preferably 10 ppm to 800 ppm.
Na and K act as crystallization accelerators in order to stabilize the crystal structure of crystalline silica such as cristobalite and tridymite.
When Na and K are contained in a total content of 10 ppm or more, quartz glass contains microcrystals, so that an effect as a scattering layer can be obtained, and an improvement in light extraction efficiency can be expected. In addition, when a light source including high-energy light with a wavelength of 230 nm or less, which is unnecessary for sterilization applications, such as a low-pressure UV lamp, is prevented from being locally irradiated with high-energy light with a wavelength of 230 nm or less. Deterioration can be suppressed.
On the other hand, by setting the total content of Na and K to 800 ppm or less, it is possible to prevent crystallization from proceeding further and increase the influence of scattering. It is preferable because light distribution can be easily controlled by giving a shape instead of a mold.

In the quartz glass of the present invention, the total content of Na and K is preferably 10 ppm to 800 ppm, more preferably 15 ppm or more, further preferably 20 ppm or more, further preferably 25 ppm or more, and further preferably 40 ppm or more. , 50 ppm or more is still more preferable, and 80 ppm or more is particularly preferable. Moreover, 600 ppm or less is more preferable, 580 ppm or less is more preferable, 200 ppm or less is further more preferable, and 130 ppm or less is further more preferable.

The quartz glass of the present invention may contain elements other than Na and K as long as the optical properties are not adversely affected.
Specifically, one or more elements selected from the group consisting of Al, Mg, Ca and Fe may be contained. The total content of these elements is preferably 1 ppm or more and less than 800 ppm. By making the total content of these elements less than 800 ppm, it is possible to prevent crystallization from proceeding further and increase the influence of scattering, and the shape of the window member can be changed to a lens type, a dome type, a shell type, etc. Instead, it is preferable because light distribution control by providing a shape becomes easy.
The total content of these elements is more preferably 5 ppm or more and less than 580 ppm, and further preferably less than 100 ppm.

In the quartz glass of the present invention, the number of scatterers having an average diameter of 1 to 50 μm is preferably 50 to 5000 per cm ² . As the scatterer, voids (holes), crystals, and opals are considered, and at least one selected from these is preferable.
If 50 to 5000 scatterers per 1 cm ² are present in the quartz glass, the haze value becomes high, preferably 0.5% or more. Thereby, the effect as a scattering layer is acquired and the raise of light extraction efficiency can be anticipated.
By setting the number of the scatterers per 1 cm ² to 5000 or less, the influence of scattering can be prevented, and the shape of the window material is changed to a lens shape, a dome shape, a bullet shape, etc. It is preferable because light distribution can be easily controlled by imparting. The number of scatterers is more preferably 500 or less.

The quartz glass of the present invention preferably has a haze value of 0.1% or more and less than 10%, more preferably 0.5% or more. The reason why the haze value is preferably 0.1% or more is as described above. On the other hand, if the haze value is less than 10%, the influence of scattering can be prevented from increasing, and the shape of the window member is changed to a lens type, a dome type, a bullet type, etc. It is preferable because light control is easy.

The quartz glass of the present invention has a linear transmittance (%) at a wavelength of 265 nm (converted to a thickness of 1 mm) of 80% or more, a linear transmittance (%) at a wavelength of 230 nm (converted to a thickness of 1 mm), and a linear transmittance (%) at a wavelength of 200 nm. ) (In terms of 1 mm thickness) ΔT is preferably 10 to 50%.
If it is the said range, deterioration of the peripheral member by having irradiated high energy light with a wavelength of 230 nm or less locally can be suppressed, having a high transmittance | permeability with a wavelength of 265 nm with a bactericidal effect. The linear transmittance (%) at the wavelength of 265 nm is more preferably 85% or more.

Further, as a member for an ultraviolet light emitting element using the quartz glass of the present invention, in addition to the one in which the light distribution is controlled by giving the shape to the quartz glass, the one in which the quartz glass and the bonding agent are integrated, A preferable embodiment is one in which quartz glass is AR-coated.

The quartz glass of the present invention can be produced by a gel cast method. Specifically, the following steps 1 to 8 may be performed in order.
Step 1: Dispersion Preparation Step for Dispersing Raw Material Silica Powder in a Solvent Step 2: Adding a Curable Resin, Curing Agent, Curing Catalyst, and Surfactant to the Dispersion Obtained in Step 1 to Silica Liquid preparation step for preparing a mixed solution of curable resin and curable resin Step 3: Molding step for pouring and filling the liquid mixture obtained in Step 2 Step 4: Curing step for curing the mixed solution in the mold Step 5: Demolding process for removing the cured molded body from the mold 6: Degreasing process for burning off organic substances such as curable resin contained in the dried molded body 7: Firing process for sintering the degreased molded body to obtain quartz glass Step 8: Heat treatment step of heating the sintered compact in a gas atmosphere Details of each step are described below.

(Process 1)
The raw material silica powder used in Step 1 preferably has a purity of 99.0% or more, more preferably a purity of 99.5% or more, and further preferably a purity of 99.9% or more.
The raw silica powder preferably has an average particle size of 5 nm to 400 nm, more preferably an average particle size of 7 nm to 350 nm, and still more preferably an average particle size of 12 nm to 300 nm. In Examples described later, raw material silica powders having an average particle diameter of 20 nm (Examples 1, 2, 4, 5) and an average particle diameter of 120 nm (Example 3) were used.

The method of dispersing the raw silica powder in the solvent in Step 1 is not particularly limited as long as the aggregation of the raw silica powder can be dissociated, but in the examples described later, an ultrasonic homogenizer (Examples 1, 2, 3, 4). Alternatively, an ultrasonic cleaner (Example 5) was used. Moreover, in order to dissociate and further disperse the aggregation of the silica powder, a pH adjuster, a surfactant, a polymer dispersant and the like can be appropriately selected and added. The pH adjuster, surfactant, polymer dispersant and the like are preferably those that do not adversely affect the gelation of the curable resin described below. Examples of the solvent include pure water.

As the basic pH adjuster, a basic organic substance can be used. For example, alkanolamines such as ammonia, monoethanolamine, diethanolamine, and triethanolamine, choline, guanidines, tetramethylammonium hydroxide, and the like. A quaternary ammonium salt etc. are mentioned.
As the acidic pH adjuster, inorganic acids and organic acids and salts thereof can be used. For example, phosphoric acid, nitric acid, citric acid, malic acid, acetic acid, lactic acid, oxalic acid, tartaric acid, salts thereof, amino acids And amphoteric salts.

Surfactants include, for example, alkylamine salts, aliphatic or aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts such as pyridinium and imidazolium, and phosphonium or sulfonium salts containing aliphatic or heterocyclic rings, Examples include acetylene glycol.
Polymer dispersing agents include polymers having primary to tertiary amines, quaternary ammonium bases or quaternary phosphonium bases in the polymer main chain or side chain, homopolymers of acrylic acid or salts thereof, And a functional aminocarboxylic acid polymer, or a (co) polymer of an acrylic ester.
These pH adjusters, surfactants and polymer dispersants may be used alone or in combination of two or more.

Note that filtering may be performed to remove aggregates remaining in the dispersion. In the examples described later, as a filtering method, filtering was performed by installing a depth filter in an air pressure-feed type filtering device.

(Process 2)
In step 2, it is preferable to use a solvent. The mold can be easily filled in the step 3 by adjusting the viscosity of the liquid mixture by using a solvent to form a slurry. Solvents used for this purpose include, for example, pure water such as ion-exchanged water and distilled water, and aqueous solvents that are mixtures of these with alcohols, ethers, amides, ethanolamines, acetone, hexane, and the like. Organic solvents can be used. A surfactant can also be added to the solvent for the purpose of defoaming and defoaming. Of these, aqueous solvents such as ion-exchanged water, pure water, and aqueous solvents are preferable from the viewpoint of production cost and environmental load.

Examples of the curable resin used in Step 2 include melamine resin, phenol resin, epoxy resin, acrylic resin, and urethane resin. Epoxy resins are preferred in that the molded article has high shape retention and is cured in the air atmosphere, and acrylic resins are preferred in that the reaction proceeds rapidly at room temperature.

Examples of the epoxy resin include glycidyl such as diglycidyl ether type epoxy resins of bisphenols such as bisphenol A type and bisphenol F type, phenol novolac type epoxy resins, cresol novolac type epoxy resins, glycidyl amine type epoxy resins, aliphatic epoxy resins, and the like. Examples include ether type epoxy resins, glycidyl ester type epoxy resins, methyl glycidyl ether type epoxy resins, cyclohexene oxide type epoxy resins, and rubber-modified epoxy resins.
Examples of the monomer that reacts to form an acrylic resin include acrylic acid, methacrylamide, methacrylic acid, methoxy (polyethylene glycol) monomethacrylate, n-vinyl pyrrolidone, acrylamide, alkyl acrylamide, alkyl methacrylamide, alkyl acrylate, and alkyl methacrylate. , Dimethylaminoethyl methacrylate, dimethylaminopropyl methacrylamide, hydroxyalkyl acrylamide, hydroxyalkyl methacrylamide, hydroxyalkyl acrylate, hydroxyalkyl methacrylate, methacrylatoethyltrimethylammonium chloride, methacrylamidepropyltrimethylammonium chloride, p-styrenesulfonic acid, p -Styrene sulfonate .

When an epoxy resin is used as the curable resin, the average molecular weight is preferably 20 to 30000. The average number of epoxy functional groups of the epoxy resin is preferably 2 to 10. Thereby, a certain strength is obtained at the time of demolding in step 5, and sufficient pot life can be secured at the time of molding in step 3.
As described above, an aqueous solvent is preferable from the viewpoint of production cost and environmental load. Therefore, the curable resin is also preferably water-soluble, and the water-soluble epoxy resin preferably has a water content of 70 to 100%.
A curable resin may be used independently and may be used in combination of 2 or more type.

The compounding quantity of curable resin can be selected suitably, and it is preferable that the weight ratio with respect to a silica powder is 0.1-1.0.

The curing agent used in step 2 is for curing the curable resin, and is selected according to the curable resin to be used. Examples of the epoxy resin curing agent include amine curing agents, acid anhydride curing agents, and polyamide curing agents. An amine-based curing agent is preferable in that the reaction is rapid, and an acid anhydride-based curing agent is preferable in that a cured product having excellent thermal shock resistance can be obtained.
Examples of the amine curing agent include aliphatic amines, alicyclic amines, aromatic amines, modified polyaminoamides, modified aliphatic polyamines, and the like, and any of monoamines, diamines, triamines, and polyamines can be used.
Examples of the acid anhydride curing agent include methyltetrahydrophthalic anhydride, dibasic acid polyanhydride, and the like.
Examples of the acrylic resin curing agent include radical polymerization initiators and cationic polymerization initiators. Examples of the radical polymerization initiator include peroxides such as ammonium persulfate, sodium persulfate, and potassium persulfate, 2,2′-azobis (isobutyronitrile) (AIBN), 2,2′-azobis (2-methylbutyrate). Ronitrile) (AMBN), 2,2′-azobis (2,4-dimethylvaleronitrile) (ADVN), 1,1′-azobis (1-cyclohexanecarbonitrile) (ACHN), dimethyl-2,2′- Azobisisobutyrate (MAIB), 4,4′-azobis (4-cyanovaleric acid) (ACVA), 1,1′-azobis (1-acetoxy-1-phenylethane), 2,2′-azobis ( 2-methylbutyramide), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylamidinopropane) disalt Acid salt, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2 '-Azobis (2,4,4-trimethylpentane), 2-cyano-2-propylazoformamide, 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2'-azobis (N And azo compounds such as (cyclohexyl-2-methylpropionamide). Examples of the cationic polymerization initiator include onium salts such as benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, diazonium salts, iodonium salts, and sulfonium salts.

The curing catalyst used in step 2 is to accelerate the curing of the curable resin, and is selected according to the curable resin to be used. Examples of the curing catalyst include tertiary amines and imidazoles.
Tertiary amines include benzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol and the like.
Examples of imidazoles include 2-methylimidazole, 1,2-dimethylimidazole, N-benzyl-2-methylimidazole, 2-ethyl-4-methylimidazole, and the like.

When the quartz glass to be produced contains one or more elements selected from the group consisting of Na and / or K, or Al, Mg, Ca and Fe, the content of these elements in the liquid mixture is predetermined. What is necessary is just to prepare a liquid mixture so that it may become content of.
The content of the element in the mixed solution is adjusted by appropriately selecting the metal content contained in the raw silica powder, pH adjuster, dispersant, surfactant, curable resin, curing agent, and curing catalyst. Alternatively, it may be adjusted by adding a salt of the above element, or a combination thereof.
When adding the salt of the said element, it is not limited to the addition in the process 2, You may add in the process 3 (molding process), the process 6 (degreasing process), and the process 7 (baking process).

The means for mixing the components in step 2 is not particularly limited, but a rotating and revolving mixer was used in the examples described later.
When mixing each component in the step 2, it is preferable to perform defoaming. By defoaming, in the step 4 (curing step), it is possible to prevent pores caused by bubbles in the slurry from entering the molded body. Defoaming can be carried out while mixing each component using a vacuum rotation and revolution mixer.

The type and shape of the mold used in step 3 are not particularly limited, and can be appropriately selected according to the quartz glass to be manufactured. A metal mold, a resin mold, or a silicone rubber mold can be used.

The conditions for curing the mixed solution in Step 4 are not particularly limited, and can be appropriately selected according to the curable resin, the curing agent, and the curing catalyst to be used. In the examples described later, the mixed solution filled in the mold was allowed to stand at room temperature and cured.

It is preferable to carry out step 6 after the molded body removed from the mold in step 5 is dried.

In step 6, the dried molded body is kept at a predetermined temperature for a predetermined time using a heating furnace such as an electric furnace to burn off organic substances such as a curable resin contained in the molded body. The heating temperature and the time for holding at the temperature are not particularly limited, but in the examples described later, held at a temperature of 550 ° C. or lower for 24 hours (Examples 1, 2, 3) or 168 hours (Examples 4, 5). Did.

In step 7, the green body degreased in step 6 is sintered to obtain quartz glass. The sintering conditions are not particularly limited. In Examples described later, vacuum baking (Examples 1, 3, 4, 5, 6) or atmospheric baking (Example 2) was performed at 1125 ° C.

In step 8, heat treatment is performed in a gas atmosphere in order to adjust the transmittance characteristics of the sintered quartz glass. If it is not necessary to adjust the transmittance characteristic, it may be omitted. The type of atmosphere gas and heat treatment conditions are not particularly limited, but heat treatment in a hydrogen atmosphere is preferable in order to adjust the transmittance in the deep ultraviolet region. In Examples described later, heat treatment was performed for 10 hours at 600 ° C. in an atmosphere of 100% hydrogen (Examples 1, 2, and 3).

Hereinafter, the present invention will be further described using examples. Examples 1 to 5 correspond to Examples 1 to 5, and Example 6 corresponds to Comparative Example 1.

(Example 1)
The steps 1 to 8 described above were performed to obtain quartz glass.
In Step 1, 33.9 parts by mass of raw silica powder having a purity of 99.9% or more, an average particle diameter of 20 nm, and a specific surface area of 90 m ² / g, and water adjusted to pH 13 using a pH adjuster as a solvent 66. A dispersion was prepared by dispersing in 1 part by mass with an ultrasonic homogenizer.
In Step 2, 88.2 parts by mass of the above dispersion, 10.0 parts by mass of a water-soluble epoxy resin, and 1.8 parts by mass of an aliphatic amine curing agent are mixed and defoamed by a rotation revolving mixer equipped with a vacuum pump. A liquid was prepared.
In step 3, the above mixture was filled in a polyethylene mold having a diameter of 30 mm × 10 mm.
In step 4, the mixed solution filled in the mold was allowed to stand at room temperature to be cured.
In step 5, the molded body was removed from the mold and then dried.
In step 6, the molded body after drying was degreased using an electric furnace at 550 ° C. or lower for 24 hours.
In step 7, the compact degreased in step 6 was vacuum fired at 1125 ° C. to obtain quartz glass.
In step 8, in order to adjust the transmittance characteristics of the molded body sintered in step 7, heat treatment was performed by holding at 600 ° C. for 10 hours in a 100% hydrogen atmosphere.
The following evaluation was performed on the quartz glass obtained by the above procedure.

(Β-OH group concentration)
A Fourier Transform Infrared Spectrophotometer (Thermo Fisher Scientific Nicolet 6700) was used. Quartz glass was processed into a circular plate shape (diameter: 1.5 cm, thickness: about 1.0 mm), and both main surfaces were mirror-polished. Analysis was carried out under the following conditions by electronic cooling DTGS.
Integration: 128 times, resolution: 8 cm ⁻¹ , measurement range: 4000 to 400 cm ⁻¹
In the IR spectrum, a Si—OH-derived peak is detected at 2500 to 3900 cm ⁻¹ . When the absorbance at about 3500 cm ⁻¹ is A (Peak) and the absorbance at 3955 cm ⁻¹ as the baseline is A (Base), the Si—OH peak absorbance A (Si—OH) is A (Si—OH) = A (Peak) -A (Base). A value obtained by normalizing A (Si—OH) to a thickness equivalent to 1 mm by the glass thickness was defined as the β-OH group concentration.

(Metal element (K, Na, Al, Mg, Ca, Fe) content)
An ICP mass spectrometer (Agilent 8800, Agilent Technologies Inc.) was used. The crushed quartz glass was decomposed by adding hydrofluoric acid to the glass and heating. After decomposition, nitric acid is added to a constant amount, and the concentration of each metal element (K, Na, Al, Mg, Ca, Fe) is measured by ICP mass spectrometry. The concentration is calculated from a calibration curve prepared using a standard solution. The content of each metal element (K, Na, Al, Mg, Ca, Fe) in the quartz glass was calculated from the measured concentration and the decomposition amount of the quartz glass.

(Number of scatterers (crystals) and average diameter (average crystal diameter))
An optical microscope (Nikon ELIPSE LV100) was used. Quartz glass was processed into a circular plate shape (diameter: 1.5 cm, thickness: about 1.0 mm), and both main surfaces were mirror-polished. The number of scatterers was calculated by counting the number of crystals observed on the 1.5 × 1.5 μm observation surface and calculating the number of scatterers per unit volume. The average diameter was calculated by dividing the sum of the diameters of the scatterers by the number of scatterers.

(CIL evaluation, crack occurrence rate)
A micro Vickers hardness tester (HMV-2, Shimadzu Corporation) was used. Quartz glass was processed into a circular plate shape (diameter: 1.5 cm, thickness: about 1.0 mm), and both main surfaces were mirror-polished. In an atmosphere having a temperature of 23 ° C. and a dew point of −2.4 ° C., the Vickers indenter was pushed for 15 seconds, then the Vickers indenter was removed, and the presence or absence of cracks near the indentation was observed. Ten point impressions were made at 100 μm intervals with 5 loads of 0.1 kgf, 0.2 kgf, 0.3 kgf, 0.5 kgf, and 1.0 kgf, and the crack occurrence rate of each load was calculated. Note that the load and crack occurrence rate are plotted, and the load at which 50% cracking occurs (the crack occurrence rate is 50%) is the CIL value.

(Laser processability)
Quartz glass was processed into a circular plate shape (diameter: 1.5 cm, thickness: about 1.0 mm), and both main surfaces were mirror-polished. A semiconductor laser (femtosecond laser) having a center wavelength of 1552 nm, a pulse width of 680 femtoseconds, and an average output of 10 W was condensed inside the sample and scanned in the width direction to continuously put the modified layer inside. By applying stress with a roller, the modified layer was separated from the modified layer at a position along the planned dividing line. The sectional surface was observed using an optical microscope, and the depth of the modified layer was measured when the number of scans was one.

(Transmittance)
A spectrophotometer (PerkinElmer Lambda 900) was used. Quartz glass was processed into a circular plate shape (diameter: 1.5 cm, thickness: about 1.0 mm), and both main surfaces were mirror-polished. The linear transmittance and the total light transmittance using an integrating sphere were measured at a measurement wavelength range of 200 to 800 nm and a scanning speed of 60 nm / min. The measured value was converted into a transmittance of 1 mm thickness.

(Haze value)
A haze meter (HZ-2, Suga Test Instruments Co., Ltd.) was used. Quartz glass was processed into a circular plate shape (diameter: 1.5 cm, thickness: about 1.0 mm), both main surfaces were mirror-polished, and the haze value was measured.

(Example 2)
In Step 7, instead of vacuum firing, the molded body degreased in Step 6 was fired in the air at 1125 ° C. The same procedure as in Example 1 was performed except for step 7.

(Example 3)
In step 1, 62.9 parts by mass of raw silica powder having a purity of 99.9% or more, an average particle diameter of 100 nm, and a specific surface area of 55 to 65 m ² / g, and water adjusted to pH 13 using a pH adjuster as a solvent 37.1 parts by mass was dispersed with an ultrasonic homogenizer to prepare a dispersion.
In step 2, 94.1 parts by mass of the above dispersion, 5.0 parts by mass of a water-soluble epoxy resin, and 0.9 parts by mass of an aliphatic amine curing agent are mixed and defoamed by a rotation-revolving mixer equipped with a vacuum pump. A liquid was prepared.
In the following steps, the same procedure as in Example 1 was performed to obtain quartz glass.

(Example 4)
In Step 2, 88.5 parts by mass of the above dispersion, 10.0 parts by mass of a water-soluble epoxy resin, 1.0 part by mass of an aliphatic amine curing agent, and 0.5 parts by mass of a tertiary amine catalyst were mounted on a vacuum pump. A mixed solution was prepared by mixing and defoaming using a mixer.
In step 6, the molded body after drying was degreased by holding at 550 ° C. or lower for 168 hours using an electric furnace.
Step 8 was not performed.
The same procedure as in Example 1 was performed except for Steps 2, 6, and 8.

(Example 5)
An ultrasonic washer was used instead of the ultrasonic homogenizer for the preparation of the dispersion in Step 1. In step 6, the molded body after drying was degreased by holding at 550 ° C. or lower for 168 hours using an electric furnace.
Step 8 was not performed.
The same procedure as in Example 1 was performed except for Steps 2, 6, and 8.

(Example 6)
The same procedure as in Example 1 was performed except that synthetic quartz glass (Asahi Glass Co., Ltd., AQ series) synthesized by a flame hydrolysis method was used, and the samples for each evaluation were plate-shaped (3 cm × 3 cm × 1 mmt). .

For the quartz glass or synthetic quartz glass of Examples 1 to 6, the β-OH concentration (ppm), the content of each metal element (ppm by weight), the number of scatterers having an average diameter of 1 to 50 μm (pieces / cm ² ), and Table 1 shows the average diameter of the scatterer, Table 2 shows the evaluation results of CIL evaluation and laser processability, and Table 3 shows the optical characteristics. The total light transmittance and the linear transmittance in Table 3 are values in terms of 1 mm thickness. In addition, the blank in a table | surface shows having not measured.

 

 

Since the quartz glass of Examples 1 to 5 has a CIL value of 0.2 to 0.5 kgf, a modified layer containing fine cracks by irradiation with a femtosecond laser that is an ultrashort pulse laser (beginning of cleaving) Is wider than Example 6 and is excellent in laser processability when a wafer-shaped quartz glass is shredded by laser processing.
The quartz glass of Examples 1 to 3 has a total light transmittance (%) (wavelength 1 mm conversion) at a wavelength of 265 nm, which is important for sterilization applications, of 85% or more, and a haze value of 0.5% or more and less than 5%. The effect as a scattering layer is obtained, and the improvement of light extraction efficiency can be expected, and it is excellent as a window member.
The quartz glass of Examples 1 to 5 has a wavelength-selective difference ΔT of 10 to 50% between the linear transmittance (%) at a wavelength of 265 nm (converted to a thickness of 1 mm) and the linear transmittance (%) at a wavelength of 200 nm (converted to a thickness of 1 mm). Since it has optical transparency, it can be expected to absorb light during high-energy laser processing and have excellent processability.
The quartz glass of Examples 1 to 5 has a linear transmittance (%) at a wavelength of 265 nm (converted to a thickness of 1 mm) of 80% or more, a linear transmittance (%) at a wavelength of 230 nm (converted to a thickness of 1 mm), and a linear transmittance at a wavelength of 200 nm ( %) (1 mm thickness equivalent) difference ΔT is 10 to 50%, and has a wavelength-selective optical transparency, so that it has a high transmittance in a wide wavelength range of 270 to 230 nm having a bactericidal effect. Wavelength-selective optical transparency that can suppress degradation is achieved.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on Jan. 16, 2017 (Japanese Patent Application No. 2017-5165), the contents of which are incorporated herein by reference.

Claims (12)

1. Quartz glass with a Vickers indentation load of 0.1 to 0.5 kgf with a 50% crack generation rate when indentations are formed on the surface using a Vickers indenter.
2. The quartz glass according to claim 1, wherein the β-OH group concentration converted from the Si-OH-derived peak at 2500 to 3900 cm ^{-1 in} the IR spectrum is 10 to 800 ppm.
3. The quartz according to claim 1 or 2, wherein the difference ΔT between the linear transmittance (%) at a wavelength of 265 nm (converted to a thickness of 1 mm) and the linear transmittance (%) at a wavelength of 200 nm (converted to a thickness of 1 mm) is 10 to 50%. Glass.
4. The quartz glass according to any one of claims 1 to 3, wherein the total light transmittance (%) at a wavelength of 265 nm (in terms of thickness 1 mm) is 85% or more.
5. The quartz glass according to any one of claims 1 to 4, wherein the linear transmittance (%) at a wavelength of 265 nm (in terms of thickness 1 mm) is 60% or more.
6. The quartz glass according to any one of claims 1 to 5, wherein the total content of Na and K is 10 to 800 ppm.
7. The number of scatterers having an average diameter of 1 to 50 μm is 50 to 5000 per cm ² , and the scatterers are at least one selected from the group consisting of holes, crystals, and opals. Quartz glass of any one of these.
8. Linear transmittance (%) at a wavelength of 265 nm (converted to 1 mm thickness) is 80% or more, and linear transmittance (%) at a wavelength of 230 nm (converted to 1 mm thickness) and linear transmittance (%) at a wavelength of 200 nm (converted to 1 mm thickness) And quartz glass having a difference ΔT of 10 to 50%.
9. A member for an ultraviolet light-emitting element using the quartz glass according to any one of claims 1 to 8.
10. A member for an ultraviolet light-emitting element in which light distribution is controlled by imparting a shape to the quartz glass according to any one of claims 1 to 8.
11. A member for an ultraviolet light emitting element, wherein the quartz glass according to any one of claims 1 to 8 and the bonding agent are integrated.
12. A member for an ultraviolet light emitting element, wherein the quartz glass according to any one of claims 1 to 8 is AR-coated.