阅读说明：本技术 带防反射膜的玻璃基板和光学部件 (Glass substrate with antireflection film and optical component ) 是由 赤尾安彦 藤原晃男 于 2019-01-30 设计创作，主要内容包括：本发明提供使用了高折射率的玻璃且具有优异的强度的带防反射膜的玻璃基板以及使用其的光学部件。上述带防反射膜的玻璃基板具备由折射率(n<Sub>d</Sub>)为1.68～2.00的玻璃构成的板厚为0.01～2mm的玻璃基板和设置于该玻璃基板的至少一个主表面上的防反射膜。(The invention provides a glass substrate with an anti-reflection film, which uses glass with high refractive index and has excellent strength, and an optical component using the same. On the upper partThe glass substrate with the anti-reflection film has a refractive index (n) d ) A glass substrate having a thickness of 0.01 to 2mm and made of 1.68 to 2.00 mm glass, and an antireflection film provided on at least one main surface of the glass substrate.)

1. A glass substrate with an antireflection film, characterized by having a refractive index n_dThe antireflection film comprises a glass substrate having a thickness of 0.01 to 2mm and made of 1.68 to 2.00 mm glass, and an antireflection film provided on at least one main surface of the glass substrate.

2. The antireflection film-provided glass substrate according to claim 1, wherein the hardness of the antireflection film measured by a nano indentation method using a glass indenter under a load of 100 μ N is 3.0GPa to 6.0 GPa.

3. The antireflection film-provided glass substrate according to claim 1 or 2, wherein a surface strength of the surface having the antireflection film, which is measured by Ring-in-Ring test, Ring on Ring test, is 600N to 1200N in terms of a value of 0.5mm in thickness of the glass substrate.

4. The antireflection film-provided glass substrate according to claim 1 to 3, wherein the antireflection film is formed by alternately laminating a high refractive index film containing 1 or more kinds selected from titanium oxide, niobium oxide and tantalum oxide and a low refractive index film composed of 1 or more kinds selected from silicon oxide, aluminum oxide and magnesium oxide.

5. The antireflection film-provided glass substrate according to claim 1 to 4, wherein the density d of the glass is 4.0g/cm³In the following, the following description is given,

and the viscosity of the glass becomes a temperature T of log η -2₂Is 800 to 1200 ℃.

6. The antireflection film-provided glass substrate according to claim 1 to 5, wherein the glass has a composition, expressed in mass% on an oxide basis, of:

Nb₂O₅：5％～65％，

selected from BaO, TiO₂、ZrO₂、WO₃And Ln₂O₃At least 1 of: 0 to 30 percent, wherein Ln is at least 1 selected from Y, La, Gd, Yb and Lu,

SiO₂：15％～50％，

Li₂O+Na₂O+K₂O：2％～20％，

Li₂O/(Li₂O+Na₂O+K₂o): 0.45 or less.

7. The antireflection film-provided glass substrate according to claim 1 to 6, wherein the glass has a composition, expressed in mass% on an oxide basis, of:

B₂O₃：0％～10％，

MgO：0％～10％，

CaO：0％～15％，

SrO：0％～15％，

BaO：0％～15％，

Li₂O：0％～9％，

Na₂O：0％～10％，

K₂O：0％～10％，

Al₂O₃：0％～5％，

TiO₂：0％～15％，

WO₃：0％～15％，

ZrO₂：0％～15％，

ZnO：0％～15％。

8. the antireflection film-equipped glass substrate according to claim 1 to 7, wherein the glass has a devitrification temperature of 1200 ℃ or lower.

9. The antireflection film-equipped glass substrate according to claim 1 to 8, wherein the glass has a transmittance T of light at a wavelength of 360nm when produced into a glass sheet having a thickness of 1mm₃₆₀Is more than 30 percent.

10. The antireflection film-provided glass substrate according to claim 1 to 9, wherein the Young's modulus E of the glass is 60GPa or more.

11. The antireflection film-coated glass substrate according to claim 1 to 10, wherein the glass has a water resistance of at least class 2 and an acid resistance of at least class 1 as measured according to the Japan optical glass industry Association standards.

12. The antireflection film-provided glass substrate according to claim 1 to 11, wherein the glass has a glass transition temperature Tg of 500 to 700 ℃ and an Abbe number v_d50 or less and a thermal expansion coefficient α of 50 to 350 ℃ of 50 to 150 × 10^－7/K。

13. The antireflection film-equipped glass substrate according to any one of claims 1 to 12, wherein an area of one main surface of the glass substrate is 8cm²The above.

14. The antireflection film-equipped glass substrate according to claim 1 to 13, wherein the glass substrate is formed such that the area of one main surface of the glass substrate is 25cm by polishing both the opposite main surfaces of the glass substrate²The LTV of the glass plate of (2) or less.

15. The antireflection film-equipped glass substrate according to claim 1 to 14, wherein when the glass is formed into a circular glass plate having a diameter of 8 inches, the warpage of at least one main surface is 50 μm or less.

16. The antireflection film-equipped glass substrate according to claim 1 to 15, wherein at least one main surface of the glass substrate has a surface roughness Ra of 2nm or less.

17. An optical member comprising the antireflection film-provided glass substrate according to claim 1 to 16.

Technical Field

The present invention relates to a glass substrate with an antireflection film and an optical component using the same.

Background

As glasses used for wearable devices, for example, glasses with a projector, glasses-type or goggle-type displays, virtual reality augmented reality display devices, virtual image display devices, and the like, high refractive indices (for example, refractive index n) are required in view of a wide angle of an image, high brightness and high contrast, improved light guiding characteristics, and ease of processing of diffraction gratings_d1.68 or more), and thinning of glass is required for weight reduction. In addition, conventionally, a small-sized imaging glass lens having a wide imaging angle is used for applications such as an in-vehicle camera and a robot vision sensor, and a high refractive index is required for such an imaging glass lens to be further small-sized and to capture a wide range.

In general glass, an antireflection film is provided on a glass surface, particularly on at least one of a pair of opposed main surfaces, for the purpose of reducing external light reflection and improving light transmittance.

On the other hand, it is known that if a thin film is formed on one surface of a glass plate, the strength of the surface opposite to the surface of the glass plate having the thin film is reduced, and in order to prevent the reduction of the strength, it is proposed to form an insulating film made of an organic compound between the glass plate and the thin film (for example, patent document 1).

Disclosure of Invention

It is known that even in a glass plate having a low reflection film, the surface strength on the side opposite to the low reflection film is reduced. The degree of reduction in the surface strength varies depending on the material of the film, but when the degree is significant, the surface strength after film formation may be about half of that before film formation.

In addition, in applications such as the wearable device, the virtual reality augmented reality display device, and the virtual image display device described above, a main surface of the glass may be subjected to processing such as patterning by imprinting. In the glass used for the above-mentioned applications, it is desirable that cracking of the glass sheet does not occur, but when a glass sheet having low strength is used, cracking or the like may occur when the above-mentioned processing is performed.

In addition, glass having a composition with a high refractive index tends to have low strength. Therefore, it is expected that it is difficult to produce a film-coated glass having improved optical properties by forming a film on a high-refractive-index glass having a refractive index of 1.68 or more, for example, and there is a fear that such a member is provided.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a glass substrate with an antireflection film having a high refractive index and excellent strength, and an optical component using the same.

The present inventors have found that the above problems can be solved by combining a glass having a specific characteristic (for example, a refractive index of 1.68 or more) with an antireflection film to obtain a desired low reflection characteristic and to improve the surface strength without lowering the surface strength.

The glass substrate with an antireflection film of the present invention is characterized by having a refractive index (n)_d) A glass substrate having a thickness of 0.01 to 2mm and made of 1.68 to 2.00 mm glass, and an antireflection film provided on at least one main surface of the glass substrate.

The optical member of the present invention is characterized by comprising the glass substrate with an antireflection film of the present invention.

The anti-reflection film-equipped glass substrate of the present invention has a high refractive index and excellent strength. Therefore, an optical member having a high refractive index and high strength can be obtained.

Drawings

Fig. 1 is a schematic sectional view of an optical glass for explaining warping of the optical glass.

Fig. 2 is a graph showing reflection characteristics of the anti-reflection film-provided glass substrate according to the embodiment of the present invention.

Fig. 3 is a diagram schematically showing a test method for measuring the surface strength of each sample according to the example of the present invention, in which fig. 3(a) is a plan view and fig. 3(B) is a side view.

Detailed Description

Embodiments of the antireflection film-equipped glass substrate and the optical member of the present invention will be described below.

The glass substrate with the anti-reflection film of the invention has a refractive index (n)_d) A glass substrate having a thickness of 0.01mm to 2mm and made of 1.68 to 2.00 glass, and an antireflection film. The antireflection film is disposed on at least one main surface of the glass substrate. The antireflection film may be disposed on both main surfaces of the glass substrate.

The anti-reflective film-provided glass substrate of the present invention preferably has an anti-reflective film hardness (hereinafter, also referred to as film hardness) of 3.0 to 6.0GPa, more preferably 3.5 to 5.0GPa or less. The film hardness was measured by nanoindentation method using a glass-type (Berkovich) indenter at a load of 100 μ N on the surface having the antireflection film. When the film hardness is in the above range, breakage of the antireflection film surface which becomes a starting point of breakage of the antireflection film-provided glass substrate can be suppressed, and breakage, or the like of the antireflection film-provided glass substrate during processing or use can be suppressed. In addition, in the glass having the composition described later, the following preferable surface strength is easily achieved.

The surface strength of the antireflection film-equipped glass substrate of the present invention measured in a Ring on Ring (ROR: Ring on Ring) test on the surface having an antireflection film is preferably 600N to 1200N in terms of a thickness of the glass substrate of 0.5 mm. The equivalent of 0.5mm of the surface strength is more preferably 700N to 1100N, and still more preferably 750N to 950N. The surface strength is an average value of breaking strength (load) of the surface of the anti-reflection film-coated glass substrate having the anti-reflection film. The areal strength of the ROR test can be determined as follows: the antireflection film-coated glass substrates were placed on an annular support (30 mm in diameter based on the center) so that the centers of the substrates were aligned and the surface having the antireflection film faced the annular support, and an annular load portion having a diameter of 10mm (based on the center) was pressed from above the center of the antireflection film-coated glass substrate so that the center of the load portion was aligned with the center of the support, and the load was measured as the load at the time when the antireflection film-coated glass substrate was broken. The method for measuring the surface strength in the ROR test is based on ASTM C1499-01 or DIN 52292.

The conversion of the surface strength to the glass substrate thickness of 0.5mm was calculated by the square proportion of the ratio of the measured glass substrate thickness of the anti-reflection film-provided glass substrate to the reference thickness (0.5 mm). The anti-reflection film-equipped glass substrate of the present invention has an excellent strength and can suppress breakage, cracking, and the like during processing or use, because the value in terms of 0.5mm thickness of the surface strength of the anti-reflection film-equipped surface is in the above range.

The glass substrate with an antireflection film of the present invention preferably has a reflectance of 2% or less, more preferably 1% or less. If the perceived reflectance is within the above range, reflection can be sufficiently prevented. The perceived reflectance is defined in accordance with JIS Z8701. As the light source, a D65 light source can be used.

The surface roughness (Ra) of the surface of the anti-reflection film-equipped glass substrate of the present invention is preferably 2.0nm or less. When Ra is 2.0nm or less, the diffuse reflection on the surface of the antireflection film is suppressed, and the ghost phenomenon and deformation can be prevented. Ra is more preferably 1.7nm or less, still more preferably 1.4nm or less, still more preferably 1.2nm or less, and particularly preferably 1nm or less. Here, Ra is an arithmetic average roughness defined in JIS B0601 (2001), and in the present specification, is a value obtained by measuring a square region of 2 μm × 2 μm using an Atomic Force Microscope (AFM).

< glass substrate >

In the anti-reflection film-equipped glass substrate of the present invention, the glass substrate has a refractive index (n)_d) Is made of 1.68 to 2.00 glass. Since n is_d1.68 or more, the antireflection film-equipped glass substrate of the present invention is usedIn the case of a wearable device, it is preferable to realize a wide angle of an image, high brightness and high contrast, improved light guiding characteristics, easy processing of a diffraction grating, and the like. Further, the imaging lens is preferably used for a small-sized imaging lens having a wide imaging angle for use in an in-vehicle camera, a robot vision sensor, or the like, because the imaging lens is smaller and has a wide imaging range. n is_dPreferably 1.70 or more, more preferably 1.73 or more, further preferably 1.74 or more, and further preferably 1.75 or more.

On the other hand, there is n_dThe glass having a density exceeding 2.00 tends to have a high density and a high devitrification temperature. Thus, n_dIs 2.00 or less, preferably 1.90 or less, more preferably 1.85 or less, further preferably 1.83 or less, further preferably 1.82 or less, particularly preferably 1.81 or less, and most preferably 1.80 or less.

The refractive index of the glass can be measured by processing the glass to be measured into a triangular prism having a side of 30mm and a thickness of 10mm, for example, and measuring the refractive index with a refractometer (Kalnew Co., Ltd., machine name: KPR-2000, etc.).

In the glass substrate with the anti-reflection film, the thickness of the glass substrate is 0.01-2.0 mm. When the thickness is 0.01mm or more, breakage of the glass substrate or the glass substrate with the antireflection film during handling or processing is suppressed. Further, deflection of the glass substrate with the antireflection film due to its own weight is suppressed. The thickness is more preferably 0.1mm or more, still more preferably 0.3mm or more, and still more preferably 0.5mm or more. On the other hand, if the thickness is 2.0mm or less, the optical element using the glass substrate with the antireflection film is lightweight. The thickness is more preferably 1.5mm or less, still more preferably 1.0mm or less, and still more preferably 0.8mm or less.

The density (d) of the glass used for the anti-reflection film-equipped glass substrate of the present invention is preferably 4.0g/cm³The following. Accordingly, the glass substrate with an antireflection film according to the present invention is preferable in wearing feeling of a user when used in a wearable device, and can reduce the weight of the entire device when used in an in-vehicle camera, a robot vision sensor, or the like. d is preferably 3.8g/cm³Hereinafter, more preferably 3.6g/cm³Hereinafter, more preferably 3.5g/cm³Hereinafter, more preferably 3.4g/cm³The following.

On the other hand, d is preferably 2.0g/cm in order not to scratch the surface of the glass substrate³The above. More preferably 2.2g/cm³Above, more preferably 2.3g/cm³Above, more preferably 2.4g/cm³The above. The density (d) of the glass can be measured according to JIS Z8807(1976, method for measuring weight in solution).

The glass used for the anti-reflection film-provided glass substrate of the present invention preferably has a temperature T of log η -2₂The viscosity of the glass is in the range of 800-1200 ℃. Here, log means the common logarithm (log)₁₀) And η is the viscosity at a shear stress of 0. T₂The reference temperature for the melting property is the T of the glass₂If the refractive index is too high, the glass needs to be melted at a high temperature, and therefore, in the case of a high refractive index glass, the visible light transmittance may be lowered particularly on the short wavelength side. T is₂Preferably 1180 ℃ or lower, more preferably 1150 ℃ or lower, still more preferably 1130 ℃ or lower, and still more preferably 1110 ℃ or lower.

On the other hand, if T₂If the viscosity is too low, the viscosity curve becomes steep, and the viscosity control during production becomes difficult. The glass used for the anti-reflection film-equipped glass substrate of the present invention has a glass passage T in the above-mentioned range₂The manufacturing characteristics can be improved. T is₂Preferably 970 ℃ or higher, more preferably 990 ℃ or higher, still more preferably 1010 ℃ or higher, and still more preferably 1030 ℃ or higher.

Temperature T at which viscosity η becomes log η ═ 2₂The viscosity can be measured by heating a sample and using a rotational viscometer, and the measurement result of the viscosity can be used.

The glass used for the anti-reflection film-equipped glass substrate of the present invention preferably has a devitrification temperature of 1200 ℃. With such characteristics, devitrification of the glass during molding can be suppressed, and the moldability is good. The devitrification temperature is more preferably 1175 ℃ or lower, still more preferably 1150 ℃ or lower, still more preferably 1125 ℃ or lower, and particularly preferably 1100 ℃ or lower.

Here, the devitrification temperature is the lowest temperature at which crystals having a long side or a long diameter of 1 μm or more are not visible on the surface and inside of the glass when the heated and melted glass is cooled by natural cooling. The devitrification temperature is specifically determined as follows: about 5g of the sample was put in a platinum dish, and the sample was held at 1000 to 1400 ℃ for 1 hour at each of 10 ℃ intervals, and after cooling them naturally, the sample was observed by a microscope to see whether or not crystals were precipitated, and the lowest temperature at which crystals having a long side or a long diameter of 1 μm or more could not be observed was measured to determine the devitrification temperature.

In addition, in wearable devices, it is required to suppress a decrease in the transmittance of visible light, but the glass used for the anti-reflection film-equipped glass substrate of the present invention melts at a high temperature and may decrease in transmittance at a wavelength shorter than 400 nm. In some cases, a near-ultraviolet image is used in a vision sensor of a vehicle-mounted camera or a robot to enable recognition of an object that is difficult to recognize with visible light, and a glass used in an optical system thereof is required to have high transmittance in the near-ultraviolet region.

Therefore, when the glass used for the anti-reflection film-equipped glass substrate of the present invention is a glass plate having a thickness of 1mm, the transmittance (T) of light at a wavelength of 360nm is obtained₃₆₀) Preferably 30% or more. The glass has such characteristics, and is suitable for use in wearable devices and vehicle-mounted cameras. In particular, in a light guide body for displaying images or videos in a wearable device, the light quantity loss on the short wavelength side becomes large because the optical path length of the guided wave becomes long. In the present invention, since the transmittance on the short wavelength side of the glass used is as high as 30% or more, the loss of light amount on the short wavelength side as described above is suppressed, and thus a desired color can be easily reproduced without lowering the transmittance of the entire visible light region. In addition, the brightness of the image or video is not reduced. T is₃₆₀More preferably 40% or more, still more preferably 50% or more, still more preferably 60% or more, particularly preferably 65% or more, and most preferably 70% or more. T is₃₆₀Can be applied to a glass plate having both surfaces mirror-polished, for example, to a thickness of 1mmThe measurement was carried out using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies).

The young's modulus (E) of the glass used for the anti-reflection film-provided glass substrate of the present invention is preferably 60GPa or more. With this characteristic, when the glass substrate is used as a thin glass substrate in a wearable device, the glass substrate is advantageously less flexible when used as a lens in an in-vehicle camera, a vision sensor for a robot, or the like. In particular, when the light guide is attached to a frame of glasses or a display device, ghost phenomenon or distortion of an image or video can be prevented. E is more preferably 70GPa or more, still more preferably 80GPa or more, still more preferably 85GPa or more, and particularly preferably 90GPa or more. The Young's modulus of glass can be measured (unit: GPa) using an ultrasonic precision thickness gauge (MODEL 38DL PLUS, manufactured by OLYMPAS) using a plate-like sample having a length of 20mm X a thickness of 1mm, for example.

In the glass used for the anti-reflective coated glass substrate of the present invention, the water Resistance (RW) measured by the method for measuring chemical durability of optical glass (powder method) according to the japan optical glass industry association standard, JOGIS 06-2008, is preferably level 2 or more. Specifically, RW is measured as follows. A glass powder having a particle diameter of 420 to 600 μm was immersed in 80mL of pure water at 100 ℃ for 1 hour to measure the mass reduction ratio (%). According to the mass reduction ratio, a prescribed grade is given. Specifically, the rank 1 is determined if the mass reduction ratio is less than 0.05%, the rank 2 is determined if the mass reduction ratio is 0.05% or more and less than 0.10%, the rank 3 is determined if the mass reduction ratio is 0.10% or more and less than 0.25%, the rank 4 is determined if the mass reduction ratio is 0.25% or more and less than 0.60%, the rank 5 is determined if the mass reduction ratio is 0.60% or more and less than 1.10%, and the rank 6 is determined if the mass reduction ratio is 1.10% or more. The smaller the value of the scale, the better RW is.

In the glass used for the anti-reflection film-equipped glass substrate of the present invention, the acid Resistance (RA) measured by the method for measuring chemical durability of optical glass (powder method) of JOGIS 06-2008 is preferably level 1 or more. Specifically, RA is measured as follows. The mass reduction ratio (%) of a glass powder having a particle size of 420 to 600 μm when immersed in 80mL of a 0.01N nitric acid aqueous solution at 100 ℃ for 1 hour was measured. A prescribed grade is given according to the mass reduction ratio. Specifically, the mass reduction ratio is class 1 if it is less than 0.20%, class 2 if it is 0.20% or more and less than 0.35%, class 3 if it is 0.35% or more and less than 0.65%, class 4 if it is 0.65% or more and less than 1.20%, class 5 if it is 1.20% or more and less than 2.20%, and class 6 if it is 2.20% or more. The smaller the value of the scale, the better the RA.

Note that "equal to or more than" the predetermined level of the water Resistance (RW) and the acid Resistance (RA) indicates a level that is superior to the level and has a value less than the level.

The glass used for the anti-reflection film-equipped glass substrate of the present invention preferably has a glass transition temperature (Tg) in the range of 500 to 700 ℃. When the optical glass of the present invention has Tg in the above range, moldability by press molding and redraw molding is good. The Tg is more preferably from 520 to 680 ℃, still more preferably from 540 to 660 ℃, still more preferably from 560 to 640 ℃, and particularly preferably from 570 to 620 ℃. Tg can be measured by using, for example, a differential thermal dilatometer (TMA) according to JIS R3103-3 (2001).

Further, the Abbe number (v) of the glass used for the anti-reflection film-equipped glass substrate of the present invention_d) Preferably 50 or less. Specifically, when the glass substrate with an antireflection film of the present invention is used for a light guide plate, the low v having the above range is used_dThe optical design of the wearable device is easy, and the chromatic aberration is easy to improve, so that beautiful images and videos can be reproduced. v. of_dMore preferably 46 or less, still more preferably 42 or less, still more preferably 38 or less, and particularly preferably 34 or less. The lower limit of the abbe number of the glass is not particularly limited, but is generally 10 or more, specifically 15 or more, and more specifically 20 or more.

Abbe number of glass measured by v using a sample used for the measurement of refractive index_d＝(n_d－1)/(n_F－n_C) And (4) calculating. n is_dIs a refractive index with respect to a helium d line,n_FIs a refractive index with respect to a hydrogen F line, and n_CIs the refractive index relative to the hydrogen C line. These refractive indices can also be measured using the refractometer described above.

The glass used for the anti-reflection film-equipped glass substrate of the present invention preferably has a thermal expansion coefficient (α) of 50 to 350 ℃ of 50 to 150(× 10)^－7The glass used for the antireflection film-equipped glass substrate of the present invention has good matching with expansion of peripheral members by α having the above range, and α is more preferably 60 to 135(× 10)^－7/K), more preferably 70 to 120(× 10)^－7/K), more preferably 80 to 105(× 10)^－7/K), particularly preferably 90 to 100(× 10)^－7/K)。

The coefficient of thermal expansion (. alpha.) can be determined by measuring the linear coefficient of thermal expansion in the range of 30 to 350 ℃ by using a differential thermal expansion meter (TMA) and obtaining the average linear coefficient of thermal expansion in the range of 30 to 350 ℃ according to JIS R3102 (1995).

The area of one main surface of the glass substrate used for the antireflection film-equipped glass substrate of the present invention is preferably 8cm²The above. If the area is 8cm²As described above, a large number of optical elements can be arranged, and productivity is improved. The area is more preferably 30cm²Above, more preferably 170cm²Above, more preferably 300cm²Above, particularly preferably 1000cm²The above. On the other hand, if the area is 6500cm²Hereinafter, handling of the glass substrate becomes easy, and breakage of the glass substrate or the anti-reflection film-equipped glass substrate during handling or processing can be suppressed. The area is more preferably 4500cm²The thickness is more preferably 4000cm²Hereinafter, more preferably 3000cm²Hereinafter, particularly preferably 2000cm²The following.

25cm of one main surface of a glass substrate used for the antireflection film-equipped glass substrate of the present invention²The LTV (Local Thickness Variation) of (2) is preferably 2 μm or less. By having flatness in this range, it is possible to use imprint technology or the like on the one main surface of the glass substrateThe nanostructure having a desired shape is formed, and desired light guiding properties can be obtained. In particular, the light guide can prevent ghost phenomenon and distortion due to a difference in optical path length. The LTV is more preferably 1.8 μm or less, still more preferably 1.6 μm or less, still more preferably 1.4 μm or less, and particularly preferably 1.2 μm or less.

The LTV of the glass substrate can be measured as follows. The thickness of the glass substrate was measured at 3mm intervals on a plate-like sample of 50mm × 50mm × 1mm by a non-contact laser displacement meter (for example, manufactured by NanoMetro, manufactured by Takara Shuzo Co., Ltd.) to calculate LTV.

The glass used for the anti-reflection film-equipped glass substrate of the present invention is preferably a glass plate having a circular shape with a diameter of 8 inches and a warp of 50 μm or less. When the warp of the glass plate is 50 μm or less, a nanostructure having a desired shape can be formed on one main surface by a imprint technique or the like, and desired light guiding properties can be obtained. When a plurality of light guide bodies are to be obtained, a light guide body with stable quality is obtained. The warp of the glass plate is more preferably 40 μm or less, still more preferably 30 μm or less, and particularly preferably 20 μm or less.

The warp of the glass when it is formed into a circular glass plate having a diameter of 6 inches is preferably 30 μm or less. When the warp of the glass plate is 30 μm or less, a nanostructure having a desired shape can be formed on one main surface by a imprint technique or the like, and desired light guiding properties can be obtained. When a plurality of light guide bodies are to be obtained, a light guide body with stable quality is obtained. The warp of the glass plate is more preferably 20 μm or less, still more preferably 15 μm or less, and particularly preferably 10 μm or less.

FIG. 1 is a sectional view of a glass plate G1 made of glass used for the anti-reflection film-equipped glass substrate of the present invention. "warp" is a difference C between the maximum value B and the minimum value a of the distance in the perpendicular direction between the reference line G1D of the glass sheet G1 and the center line G1C of the glass sheet G1 in an arbitrary cross section orthogonal to the one main surface G1F passing through the center of the one main surface G1F of the glass sheet G1.

The intersection of the arbitrary perpendicular cross section and the one main surface G1F of the glass sheet G1 is defined as a bottom line G1A. The intersection of the arbitrary orthogonal cross section and the other main surface G1G of the glass sheet G1 is defined as an upper line G1B. Here, the center line G1C is a line connecting the centers of the glass sheets G1 in the sheet thickness direction. The center line G1C is calculated by determining the midpoint between the bottom line G1A and the upper line G1B with respect to the direction of laser irradiation described later.

Reference line G1D is determined as follows. First, the bottom line G1A is calculated based on the measurement method for eliminating the influence of the self weight. From this bottom line G1A, a straight line is obtained by the least square method. The obtained straight line is a reference line G1D. As a measurement method for eliminating the influence of the self weight, a known method can be used.

For example, the first main surface G1F of the glass sheet G1 is supported at 3 points, and the glass sheet G1 is irradiated with laser light by a laser displacement meter, and the heights of the first main surface G1F and the second main surface G1G of the glass sheet G1 from an arbitrary reference plane are measured.

Next, the glass sheet G1 was turned upside down, 3 points of the other main surface G1G opposed to 3 points supporting the one main surface G1F were supported, and the heights of the one main surface G1F and the other main surface G1G of the glass substrate G1 from an arbitrary reference plane were measured.

The influence of the self-weight is eliminated by averaging the heights of the respective measurement points before and after the inversion. For example, prior to inversion, the height of one major surface G1F is measured as above. After the glass sheet G1 was turned over, the height of the other main surface G1G was measured at a position corresponding to the measurement point of the one main surface G1F. Similarly, the height of the other major surface G1G was measured before inverting. After the glass sheet G1 was turned over, the height of one main surface G1F was measured at a position corresponding to the measurement point of the other main surface G1G. The warpage is measured, for example, by a laser displacement meter (for example, a non-contact laser displacement meter manufactured by Nano Metro, manufactured by Takara Shuzo Co., Ltd.).

In the glass substrate used for the antireflection film-equipped glass substrate of the present invention, the surface roughness Ra of one main surface is preferably 2nm or less. By having Ra in this range, a nanostructure having a desired shape can be formed on one main surface by imprint technique or the like, and desired light guiding properties can be obtained. In particular, the light guide suppresses the diffuse reflection at the interface and prevents the ghost phenomenon and distortion. Ra is more preferably 1.7nm or less, still more preferably 1.4nm or less, still more preferably 1.2nm or less, and particularly preferably 1nm or less. Here, the surface roughness Ra is an arithmetic average roughness defined in JIS B0601 (2001), and in the present specification, is a value measured by an Atomic Force Microscope (AFM) for a square region of 2 μm × 2 μm. Here, when the antireflection film is provided only on one main surface of the antireflection film-equipped glass substrate, the main surface on the opposite side of the main surface having the antireflection film is to be formed with the nanostructure, and therefore the surface roughness Ra of the main surface is preferably in the above range.

[ glass composition ]

Next, one embodiment of the composition range of each component that the glass of the present embodiment can contain will be described in detail. In the present specification, unless otherwise specified, the content of each component is expressed as mass% based on the total mass of the oxide-based glass matrix composition. In addition, "substantially not contained" in the glass used in the present invention means not containing other than inevitable impurities. The content of inevitable impurities is 0.1% or less in the present invention.

As the mother composition satisfying the characteristics of the glass used in the present invention, which has a high refractive index, good light transmittance and high melting property, for example, there is a composition containing the following components expressed by mass% based on oxides: 5 to 80 mass% of SiO as a glass forming component₂、B₂O₃And P₂O₅At least 1 kind of (B), and 5-70 wt% of modified oxide selected from MgO, CaO, SrO, BaO, ZnO and Li₂O、Na₂O、K₂O、Cs₂O、Ln₂O₃(Ln is at least 1 selected from Y, La, Gd, Yb and Lu), and 0-50% by mass of Al as an intermediate oxide₂O₃、TiO₂、ZrO₂、WO₃、Bi₂O₃、TeO₂、Ta₂O₅、Nb₂O₅At least 1 kind of oxide of (1).

Specific examples of the composition of such a glass include(1) La-B system, (2) SiO₂System (3) P₂O₅A glass of the series. In the description of the content of the glass composition, the expression "%" alone means "% by mass" unless otherwise specified.

(1) The La-B system may be exemplified by the one containing La when the total of the parent compositions is 100%₂O₃5～70％、B₂O₃5-70% of glass.

By containing more than 5% of La₂O₃The component (b) can obtain a desired high refractive index and can reduce the dispersion (increase the Abbe number). La₂O₃The content of the component (b) is preferably 10% or more, more preferably 15%, further preferably 20% or more, further preferably 25% or more.

On the other hand, by making La₂O₃The content of the component (A) is 70% or less, so that the lowering of the meltability of the glass is suppressed and the devitrification resistance of the glass is improved. La₂O₃The content of the component (b) is preferably 60% or less, more preferably 50% or less, further preferably 40% or less, further preferably 30% or less.

B₂O₃Is a glass forming component, B₂O₃The content of (b) is preferably 5 to 70% when the total amount of the mother components is 100%.

By containing more than 5% of B₂O₃Component (b) can improve the resistance of glass to devitrification and reduce the dispersion of glass. B is₂O₃The content of the component (b) is preferably 10% or more, more preferably 15% or more, and still more preferably 20% or more.

On the other hand, by making B₂O₃When the content of the component is 70% or less, a larger refractive index can be easily obtained, and deterioration of chemical durability can be suppressed. Thus, B₂O₃The content of the component (b) is preferably 50% or less, more preferably 40% or less, further preferably 30% or less, further preferably 25% or less.

SiO₂Is a glass forming component. SiO 2₂The content of (A) is 10 in total of the parent compositions0% is 0-15%. By containing SiO₂The glass is imparted with high strength and crack resistance, and the stability and chemical durability of the glass can be improved. SiO 2₂The content of (b) is preferably 2% or more, more preferably 4% or more, and further preferably 6% or more. On the other hand, SiO₂When the content of (b) is 15% or less, a component for obtaining a high refractive index can be contained. SiO 2₂The content of (b) is preferably 10% or less, more preferably 8% or less.

MgO is an arbitrary component. The content of MgO is preferably 0 to 20% when the total of the parent compositions is 100%. By containing the MgO component, the mechanical strength of the glass can be improved. The content of MgO is more preferably 1% or more, and still more preferably 3% or more. If the MgO content is 20% or less, the devitrification temperature is lowered to obtain preferable production characteristics. The content of MgO is more preferably 15% or less, still more preferably 10% or less, and still more preferably 5% or less.

CaO is an arbitrary component. The content of CaO is preferably 0 to 30% when the total of the parent compositions is 100%. By containing the CaO component, the chemical durability of the glass can be improved. The content of CaO is more preferably 1% or more, still more preferably 3% or more, still more preferably 5% or more, and particularly preferably 10% or more. If the CaO content is 30% or less, the devitrification temperature is lowered and the desired production characteristics are obtained. The content of CaO is more preferably 20% or less, and further preferably 15% or less.

SrO is an arbitrary component. The content of SrO is preferably 0 to 30% when the total of the parent compositions is 100%. The refractive index of the glass can be increased by containing the SrO component. The SrO content is more preferably 1% or more, and still more preferably 3% or more. If the SrO content is 30% or less, the devitrification temperature is lowered and desired production characteristics are obtained. The SrO content is more preferably 20% or less, still more preferably 15% or less, still more preferably 10% or less, and particularly preferably 5% or less.

BaO is an arbitrary component. The content of BaO is preferably 0 to 40% when the total of the parent compositions is 100%. The refractive index of the glass can be increased by containing the BaO component. The content of BaO is more preferably 1% or more, further preferably 3% or more, and further preferably 5% or more. If the content of BaO is 40% or less, the devitrification temperature becomes low and the desired production characteristics are obtained. The content of BaO is more preferably 30% or less, further preferably 20% or less, further preferably 15% or less, and particularly preferably 10% or less.

ZnO is an arbitrary component. The content of ZnO is preferably 0 to 30% when the total of the parent compositions is 100%. The refractive index of the glass can be increased by containing the ZnO component. The content of ZnO is more preferably 1% or more, and still more preferably 3% or more. When the content of ZnO is 30% or less, the devitrification temperature becomes low and the desired production characteristics are obtained. The content of ZnO is more preferably 20% or less, still more preferably 15% or less, still more preferably 10% or less, and particularly preferably 5% or less.

Li₂O is an arbitrary component. Li₂The content of O is preferably 0 to 15% when the total of the parent compositions is 100%. By containing Li₂O, which can improve the strength (Kc) and crack resistance (CIL). Li₂The content of O is more preferably 0.5% or more, still more preferably 1% or more, and still more preferably 3% or more. On the other hand, if Li₂When the content of O is 15% or less, the devitrification temperature becomes low and the desired production characteristics are obtained. Li₂The content of O is preferably 10% or less, more preferably 7% or less, further preferably 5% or less, and particularly preferably 4% or less.

Na₂O is an arbitrary component. Na (Na)₂The content of O is0 to 20% when the total of the parent compositions is 100%. If Na is present₂When the content of O is 20% or less, good crack resistance is obtained. Na (Na)₂The content of O is preferably 15% or less, more preferably 10% or less, further preferably 7% or less, and particularly preferably 5% or less. The glass of the present embodiment contains Na₂In the case of O, the devitrification temperature is lowered to obtain desirable production characteristics, and the content thereof is preferably 0.5% or more, more preferably 1% or more, further preferably 2% or more, and particularly preferably 3% or more.

K₂O is an arbitrary component. K₂The content of O is determined by adding the mother components0 to 20% when the content is 100%. If K is₂When the content of O is 20% or less, good crack resistance is obtained. K₂The content of O is preferably 15% or less, more preferably 10% or less, and further preferably 7% or less. Containing K₂When O is used, the devitrification temperature is lowered, and the desired production characteristics are obtained. The content thereof is preferably 0.5% or more, more preferably 1% or more, further preferably 2% or more, and particularly preferably 3% or more.

The glass of the present embodiment may contain an alkali metal component (Li) as an optional component₂O、Na₂O、K₂O)。Li₂O+Na₂O+K₂The content of O is0 to 20% when the total of the parent compositions is 100%. If Li is present₂O+Na₂O+K₂O is more than 2%, then T₂The melting temperature is easily lowered, and coloring is suppressed. Li₂O+Na₂O+K₂O is preferably 4% or more, more preferably 6% or more. In addition, by using Li₂O+Na₂O+K₂The content of O is 20% or less, and the devitrification temperature is lowered to obtain an ideal production characteristic. Li₂O+Na₂O+K₂The content of O is preferably 15% or less, more preferably 10% or less, and further preferably 8% or less. "Li₂O+Na₂O+K₂O' represents Li₂O、Na₂O and K₂The total amount of alkali metal oxide components of at least 1 of O.

In the glass of the present embodiment, Li is contained in the alkali metal component₂O is a component for improving the strength of the glass, but when the amount is large, T is₂Easily becomes low and easily devitrifies. Therefore, in the glass of the present embodiment, Li is present in a ratio of mass% based on oxides₂O/(Li₂O+Na₂O+K₂O) is preferably 0.45 or less. When the ratio is 0.45 or less, T is₂Easily becomes high and hardly devitrifies, and the formability of the glass is improved. This ratio is more preferably 0.4 or less, still more preferably 0.35 or less, and particularly preferably 0.3 or less.

Cs₂O is an arbitrary component. Cs₂The content of O is determined by adding the mother components0 to 20% when the content is 100%. If Cs₂When the content of O exceeds 0%, the devitrification temperature is lowered, and desired production characteristics are obtained. The glass of the present embodiment contains Cs₂In the case of O, the content is preferably 0.5% or more, more preferably 1% or more, further preferably 2% or more, and particularly preferably 3% or more. On the other hand, if Cs₂When the content of O is 20% or less, good crack resistance is obtained. Cs₂The content of O is preferably 15% or less, more preferably 10% or less, and further preferably 7% or less.

Ln₂O₃(Ln is at least 1 selected from Y, La, Gd, Yb and Lu) is an arbitrary component. As Ln₂O₃The total content of (B) is 5 to 55% when the total of the mother compositions is 100%. If Ln is contained₂O₃The refractive index of the glass can be increased. As Ln₂O₃The total content of (a) is preferably 10% or more, more preferably 15% or more, further preferably 20% or more, and particularly preferably 25% or more.

In addition, if Ln₂O₃When the content of (b) is 55% or less, the devitrification temperature can be reduced and the raw material cost can be reduced. Therefore, the content as the total amount is preferably 55% or less, more preferably 45% or less, further preferably 35% or less, and particularly preferably 30% or less.

Al₂O₃Is an arbitrary component. Al (Al)₂O₃The content of (B) is0 to 35% when the total amount of the mother compositions is 100%. By containing Al₂O₃The strength of the glass can be improved and the stability of the glass can be improved. Al (Al)₂O₃The content of (b) is preferably 1% or more, more preferably 3% or more, and still more preferably 5% or more.

In addition, if Al is present₂O₃When the content of (b) is 35% or less, the devitrification temperature becomes low and the desired production characteristics are obtained. Al (Al)₂O₃The content of (B) is preferably 20% or less, more preferably Al₂O₃The content of (A) is 10% or less, and Al is more preferable₂O₃The content of (A) is less than 8%.

TiO₂Is an arbitrary component. TiO 2₂The content of (B) is0 to 35% when the total amount of the mother compositions is 100%. If containing TiO₂The refractive index of the glass can be increased and the stability of the glass can be improved. TiO 2₂The content of (b) is preferably 1% or more, more preferably 5% or more, still more preferably 7% or more, and particularly preferably 10% or more.

In addition, if TiO₂When the content of (b) is 35% or less, the devitrification temperature becomes low, and the coloring of the glass is suppressed. TiO 2₂The content of (b) is preferably 25% or less, more preferably 20% or less, and further preferably 15% or less.

ZrO₂Is an arbitrary component. ZrO (ZrO)₂The content of (B) is0 to 30% when the total amount of the mother compositions is 100%. If containing ZrO₂The refractive index of the glass can be increased and the chemical durability can be improved. ZrO (ZrO)₂The content of (b) is preferably 1% or more, more preferably 5% or more, still more preferably 10% or more, and particularly preferably 15% or more.

In addition, if ZrO₂When the content of (b) is 30% or less, the devitrification temperature becomes low and the desired production characteristics are obtained. ZrO (ZrO)₂The content of (b) is preferably 20% or less, more preferably 15% or less.

WO₃Is an arbitrary component. WO₃The content of (B) is0 to 30% when the total amount of the mother compositions is 100%. If containing WO₃The refractive index of the glass can be increased. WO₃The content of (b) is preferably 1% or more, more preferably 3% or more, further preferably 5% or more, and particularly preferably 10% or more.

In addition, if WO₃When the content of (b) is 30% or less, the devitrification temperature is lowered to suppress the coloring of the glass. WO₃The content of (b) is preferably 20% or less, more preferably 15% or less.

Bi₂O₃Is an arbitrary component. Bi₂O₃The content of (B) is0 to 55% when the total amount of the mother compositions is 100%. Containing Bi₂O₃The refractive index of the glass can be increased. Bi₂O₃The content of (B) is preferably 1% or more, more preferably 5% or more,more preferably 5% or more, and particularly preferably 10% or more.

In addition, if Bi₂O₃When the content of (b) is 55% or less, the devitrification temperature is lowered to suppress the coloring of the glass. Bi₂O₃The content of (b) is preferably 35% or less, more preferably 25% or less, and further preferably 15% or less.

TeO₂Is an arbitrary component. TeO₂The content of (B) is0 to 30% when the total amount of the mother compositions is 100%. If containing TeO₂The refractive index of the glass can be increased. TeO₂The content of (b) is preferably 1% or more, more preferably 5% or more.

In addition, if TeO₂When the content of (b) is 30% or less, the devitrification temperature can be reduced and the raw material cost can be reduced. TeO₂The content of (b) is preferably 20% or less, more preferably 10% or less.

Ta₂O₅Is an arbitrary component. Ta₂O₅The content of (B) is0 to 30% when the total amount of the mother compositions is 100%. If containing Ta₂O₅The refractive index of the glass can be increased. Ta₂O₅The content of (b) is preferably 1% or more, more preferably 5% or more.

In addition, if Ta₂O₅When the content of (b) is 30% or less, the devitrification temperature can be reduced and the raw material cost can be reduced. Ta₂O₅The content of (b) is preferably 25% or less, more preferably 10% or less.

Nb₂O₅Is an arbitrary component. Nb₂O₅The content of (B) is0 to 35% when the total amount of the mother compositions is 100%. If containing Nb₂O₅The refractive index of the glass can be increased. Nb₂O₅The content of (b) is preferably 5% or more, more preferably 10% or more, and still more preferably 15% or more.

In addition, if Nb₂O₅If the content of (b) is 35% or less, the devitrification temperature can be reduced and the raw material cost can be reduced. Nb₂O₅The content of (b) is preferably 30% or less, more preferably 25% or less.

As a preferable composition of La-B, there can be exemplified a composition containing La in mass% based on oxides₂O₃：20～35％、B₂O₃：10～20％、SiO₂：0～10％、CaO：5～15％、ZnO：0～5％、TiO₂：5～15％、ZrO₂：5～10％、Nb₂O₅：15～25％、As₂O₃：0～2％、Sb₂O₃: 0 to 2% of a high refractive index glass composition.

(2) As SiO₂The system may, for example, be exemplified by a system containing SiO₂: 10 to 50% of Nb as a high refractive index component₂O₅、Ta₂O₅、Li₂O、SrO、BaO、TiO₂、ZrO₂、WO₃、Bi₂O₃、TeO₂And Ln₂O₃(Ln is at least 1 selected from Y, La, Gd, Yb and Lu): more than 30% of glass.

SiO₂Is a glass forming component. SiO 2₂The content of (B) is 10 to 50% when the total amount of the mother compositions is 100%. SiO 2₂When the content of (A) is 10% or more, the viscosity of the glass can be adjusted to a temperature T at which log η is 2₂In the preferred range, high strength and crack resistance are imparted to the glass, and the stability and chemical durability of the glass can be improved. SiO 2₂The content of (b) is preferably 15% or more, more preferably 20% or more, still more preferably 25% or more, and still more preferably 29% or more. On the other hand, SiO₂The content of (b) is 45% or less, and a component for obtaining a high refractive index may be contained. SiO 2₂The content of (b) is preferably 40% or less, more preferably 35% or less, and further preferably 30% or less.

Nb₂O₅Is an arbitrary component. By Nb₂O₅The content of (b) is 5% or more when the total of the mother compositions is 100%, the refractive index of the glass can be increased, and the Abbe number (v) can be decreased_d)。Nb₂O₅The content of (b) is preferably 15% or more, more preferably 20% or more, further preferably 25% or more, particularly preferablyMore than 30 percent.

In addition, if Nb₂O₅If the content of (b) is 70% or less, the devitrification temperature can be reduced and the raw material cost can be reduced. Nb₂O₅The content of (b) is preferably 65% or less, more preferably 60% or less, still more preferably 55% or less, and still more preferably 50% or less.

Ta₂O₅Is an arbitrary component. Ta₂O₅The content of (B) is0 to 30% when the total amount of the mother compositions is 100%. By Ta₂O₅The content of (A) is 1% or more, and the refractive index can be improved. Ta₂O₅The content of (b) is more preferably 5% or more.

In addition, if Ta₂O₅When the content of (b) is 30% or less, the devitrification temperature can be reduced and the raw material cost can be reduced. Ta₂O₅The content of (b) is preferably 25% or less, more preferably 10% or less.

The glass of the present embodiment may contain an alkali metal component (Li) as an optional component₂O，Na₂O，K₂O)。Li₂O+Na₂O+K₂The content of O is0 to 20% when the total of the parent compositions is 100%. If Li is present₂O+Na₂O+K₂O is more than 2%, then T₂The melting temperature is easily lowered, and coloring is suppressed. Li₂O+Na₂O+K₂The content of O is preferably 4% or more, more preferably 6% or more. In addition, by using Li₂O+Na₂O+K₂The content of O is 20% or less, and the devitrification temperature is lowered, thereby obtaining desirable production characteristics. Li₂O+Na₂O+K₂The content of O is preferably 15% or less, more preferably 10% or less, and further preferably 8% or less.

In the glass of the present embodiment, Li is an alkali metal component₂O is a component for improving the strength of the glass, and when the amount of O is large, T is₂Easily becomes low and easily devitrifies. Therefore, in the glass of the present embodiment, Li is present in a ratio of mass% based on oxides₂O/(Li₂O+Na₂O+K₂O) is preferably 0.45 or less. By setting the ratio to 0.45 or less, T₂The glass tends to be high in glass density, and is less susceptible to devitrification, thereby improving the formability of the glass. This ratio is more preferably 0.4 or less, still more preferably 0.35 or less, and particularly preferably 0.3 or less.

The total amount (RO) of alkaline earth metal components (MgO, CaO, SrO, BaO) and alkali metal component (Li) shown below₂O，Na₂O，K₂Total amount of O) (R'₂O) satisfies RO > 2 × R'₂In the case of O, Li₂O/(Li₂O+Na₂O+K₂O) may be 0.75 or more.

In addition, the glass of the present embodiment contains Li₂O、Na₂The alkali metal oxide of O can be chemically strengthened by replacing Li ions with Na ions or K ions and replacing Na ions with K ions. That is, if the chemical strengthening treatment is performed, the strength of the optical glass can be improved.

Li₂O is an arbitrary component. Li₂The content of O is preferably 0 to 15% when the total of the parent compositions is 100%. If containing Li₂O, the strength (Kc) and crack resistance (CIL) can be improved. Li₂The content of O is more preferably 0.5% or more, still more preferably 1% or more, and still more preferably 3% or more. On the other hand, if Li₂When the content of O is 15% or less, the devitrification temperature becomes low and the desired production characteristics are obtained. Li₂The content of O is preferably 10% or less, more preferably 9% or less, further preferably 7% or less, further preferably 5% or less, and particularly preferably 4% or less.

When the glass of the present embodiment is chemically strengthened, Li₂The content of O is preferably 1.0% or more, more preferably 1.5% or more, further preferably 2.5% or more, and particularly preferably 3.5% or more.

Na₂O is an optional component, and is a component that suppresses devitrification and lowers Tg. Na (Na)₂The content of O is 0% to 10% when the total of the parent compositions is 100%. If containing Na₂O, an excellent devitrification-inhibiting effect is obtained. On the other hand, if Na₂When O is too much, the strength and crack resistance are liable to be lowered. The glass of the present invention contains Na₂In the case of O, the content is preferably 0.5% or more, more preferably 1% or more, further preferably 2% or more, and particularly preferably 3% or more. In addition, Na₂The content of O is preferably 9% or less, more preferably 8% or less, and further preferably 7% or less.

When the glass of the present embodiment is chemically strengthened, Na₂The content of O is preferably 1.0% or more, more preferably 1.5% or more, further preferably 2.5% or more, and particularly preferably 3.5% or more.

K₂O is an optional component, and is a component for improving the meltability of the glass and for suppressing devitrification. K₂The content of O is 0% to 10% when the total of the parent compositions is 100%. If containing K₂O, the devitrification-inhibiting effect is improved. On the other hand, K₂When the amount of O is too large, the density tends to increase. K₂The content of O is preferably 0.3% or more, more preferably 0.5% or more, and further preferably 1% or more. In addition, K₂The content of O is preferably 10% or less, more preferably 8% or less, and further preferably 6% or less.

MgO is an arbitrary component. MgO is a component for improving the melting property of glass, suppressing devitrification, and adjusting optical constants such as the abbe number and refractive index of glass. On the other hand, when the amount of MgO increases, devitrification is promoted. Therefore, the content of MgO is preferably 0% to 10% when the total of the parent compositions is 100%. The content of MgO is more preferably 8% or less, and particularly preferably 6% or less. The content of MgO is preferably 0.3% or more, more preferably 0.5% or more, and still more preferably 1% or more.

CaO is an arbitrary component. CaO is a component that suppresses devitrification, but when the amount of CaO is large, crack resistance is liable to decrease. Therefore, the content of CaO is preferably 0% to 15% when the total of the mother compositions is 100%. The content of CaO is more preferably 12% or less, and particularly preferably 10% or less. The content of CaO is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

SrO is an arbitrary component. The content of SrO is preferably 0 to 30% when the total of the parent compositions is 100%. The refractive index of the glass can be increased by containing the SrO component. The SrO content is more preferably 1% or more, and still more preferably 3% or more. If the content is 30% or less, the devitrification temperature becomes low and desired production characteristics are obtained. The SrO content is more preferably 20% or less, still more preferably 15% or less, still more preferably 10% or less, and particularly preferably 5% or less.

BaO is an arbitrary component. The content of BaO is preferably 0 to 50% when the total of the parent compositions is 100%. The refractive index of the glass can be increased by containing the BaO component. More preferably 1% or more, still more preferably 3% or more, and still more preferably 5% or more. If the content is 50% or less, the devitrification temperature becomes low and the desired production characteristics are obtained. The content of BaO is more preferably 35% or less, further preferably 20% or less, further preferably 15% or less, and particularly preferably 10% or less.

TiO₂Is an arbitrary component. TiO 2₂The content of (B) is0 to 35% when the total amount of the mother compositions is 100%. If containing TiO₂The refractive index of the glass can be increased, and the stability of the glass can be improved. TiO 2₂The content of (b) is preferably 1% or more, more preferably 1.5% or more, further preferably 2.0% or more, further preferably 5% or more, particularly preferably 7% or more, and most preferably 10% or more.

In addition, if TiO₂When the content of (b) is 35% or less, the devitrification temperature becomes low, and the coloring of the glass is suppressed. TiO 2₂The content of (b) is preferably 25% or less, more preferably 20% or less, and further preferably 15% or less.

ZrO₂Is an arbitrary component. ZrO (ZrO)₂The content of (B) is0 to 30% when the total amount of the mother compositions is 100%. If containing ZrO₂The refractive index of the glass can be increased, and the chemical durability can be improved. ZrO (ZrO)₂The content of (b) is preferably 1% or more, more preferably 3.0% or more, still more preferably 3.5% or more, still more preferably 5% or more, and particularly preferably 10% or more.

In addition, if ZrO₂If the content of (B) is 30% or less, the devitrification temperature becomes lowAnd the ideal manufacturing characteristics are obtained. ZrO (ZrO)₂The content of (b) is preferably 30% or less, more preferably 20% or less, and further preferably 15% or less.

WO₃Is an arbitrary component. WO₃The content of (B) is0 to 30% when the total amount of the mother compositions is 100%. If containing WO₃The refractive index of the glass can be increased. WO₃The content of (b) is preferably 1% or more, more preferably 3% or more, further preferably 5% or more, and particularly preferably 10% or more.

In addition, if WO₃When the content of (b) is 30% or less, the devitrification temperature is lowered to suppress the coloring of the glass. WO₃The content of (b) is preferably 20% or less, more preferably 15% or less.

Bi₂O₃Is an arbitrary component. Bi₂O₃The content of (B) is0 to 55% when the total amount of the mother compositions is 100%. If containing Bi₂O₃The refractive index of the glass can be increased. Bi₂O₃The content of (b) is preferably 1% or more, more preferably 5% or more, further preferably 5% or more, and particularly preferably 10% or more.

In addition, if Bi₂O₃When the content of (b) is 55% or less, the devitrification temperature is lowered to suppress the coloring of the glass. Bi₂O₃The content of (b) is preferably 45% or less, more preferably 42% or less, still more preferably 35% or less, still more preferably 25% or less, and particularly preferably 15% or less.

TeO₂Is an arbitrary component. TeO₂The content of (B) is0 to 30% when the total amount of the mother compositions is 100%. If containing TeO₂The refractive index of the glass can be increased. TeO₂The content of (b) is preferably 1% or more, more preferably 5% or more, still more preferably 10% or more, and particularly preferably 15% or more.

In addition, if TeO₂When the content of (b) is 30% or less, the devitrification temperature can be reduced and the raw material cost can be reduced. TeO₂The content of (b) is preferably 20% or less, more preferably 10% or less.

By containing Ln₂O₃(Ln is 1 or more selected from Y, La, Gd, Yb and Lu), the refractive index of the glass can be increased. Ln₂O₃The content of (b) is preferably 1% or more, more preferably 3% or more, further preferably 5% or more, and particularly preferably 10% or more, when the total of the mother compositions is 100%. On the other hand, if Ln₂O₃When the content of (b) is 55% or less based on 100% of the total of the mother compositions, the devitrification temperature is lowered and the desired production characteristics are obtained. Ln₂O₃The total content of (b) is preferably 35% or less, more preferably 20% or less, and particularly preferably 15% or less.

B₂O₃Is an arbitrary component. B is₂O₃Is a component for lowering Tg and improving mechanical properties such as strength and crack resistance of the glass, but B is a component for lowering Tg₂O₃When the amount of (B) is large, the refractive index tends to be low. Thus, B₂O₃The content ratio of (B) is preferably 0% to 10%. B is₂O₃The content ratio of (b) is more preferably 8.5% or less, still more preferably 6.5% or less, and particularly preferably 5% or less. In addition, B₂O₃The content ratio of (b) is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

Al₂O₃Is an arbitrary component. Al (Al)₂O₃Is a component for improving chemical durability, but Al₂O₃When the amount of glass increases, the glass is easily devitrified. Thus, Al₂O₃The content ratio of (B) is preferably 0% to 5%. Al (Al)₂O₃The content ratio of (b) is more preferably 3% or less, and particularly preferably 2% or less. In addition, Al₂O₃The content ratio of (b) is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

ZnO is an arbitrary component, and is a component for improving mechanical properties such as strength and crack resistance of the glass. On the other hand, when the amount of ZnO is large, devitrification is easy, and therefore the content ratio thereof is preferably 0% to 15%. The content of ZnO is more preferably 13% or less, still more preferably 12% or less, and particularly preferably 10% or less. The content of ZnO is more preferably 0.3% or more, still more preferably 0.5% or more, and particularly preferably 1% or more.

La₂O₃Is an arbitrary component. La₂O₃Is a component for increasing the refractive index of the glass, however, La₂O₃When the amount of (B) is too large, mechanical properties are deteriorated. Thus, La₂O₃The content ratio of (B) is preferably 0% to 30%. La₂O₃The content ratio of (b) is more preferably 20% or less, still more preferably 12% or less, still more preferably 10% or less, and still more preferably 8% or less. La₂O₃Preferably, it is substantially not contained.

As₂O₃Is a harmful chemical substance, and therefore, in recent years, use of the chemical substance tends to be controlled, and disposal in an environmental countermeasure is required. Therefore, when importance is attached to the environmental influence, it is preferable that the additive does not substantially contain the environmental influence except for inevitable mixing.

In addition, the glass of the present embodiment preferably contains Sb₂O₃And SnO₂At least one of (1). These are not essential components, but may be added for the purpose of adjusting refractive index characteristics, improving meltability, suppressing coloring, improving transmittance, clarifying, improving chemical durability, and the like. When these components are contained, the total content is preferably 10% or less, more preferably 5% or less, further preferably 3% or less, and particularly preferably 1% or less.

Further, the glass of the present embodiment preferably contains F. F is not essential, but may be added for the purpose of improving meltability, improving transmittance, improving clarity, and the like. When F is contained, it is preferably 5% or less, more preferably 3% or less.

As SiO₂Preferred composition of (SiO)₂The composition A) may be represented by mass% based on oxides and contains Nb₂O₅: 5 to 65 percent of BaO and TiO₂、ZrO₂、WO₃And Ln₂O₃(Ln is at least 1 selected from Y, La, Gd, Yb and Lu): 0% -30% of SiO₂：15％～50％、Li₂O+Na₂O+K₂O is 2 to 20 percent，Li₂O/(Li₂O+Na₂O+K₂O) is 0.45 or less. As a specific composition of the high refractive index glass, B₂O₃：0％～10％、MgO：0％～10％、CaO：0％～15％、SrO：0％～15％、BaO：0％～15％、Li₂O：0％～9％、Na₂O：0％～10％、K₂O：0％～10％、Al₂O₃：0％～5％、TiO₂：0％～15％、WO₃：0％～15％、ZrO₂：0％～15％、ZnO：0％～15％。

In addition, as SiO₂Is another preferred composition (SiO)₂The composition B) may be represented by containing SiO in mass% based on oxide₂：25～40％、RO：0～10％、R’₂O：0～20％、Li₂O/R’₂O≤0.45、Ln₂O₃：0～30％、Nb₂O₅: 20 to 55% of a high refractive index glass composition. In addition, as SiO₂Other preferred compositions of (SiO)₂Composition C), expressed in mass% based on oxide, SiO₂：15～30％、Nb₂O₅：40～65％、RO：0～10％、R’₂O：0～20％、Li₂O/R’₂High refractive index glass composition with O less than or equal to 0.45. As other preferable composition (SiO)₂The composition D) may be represented by containing SiO in mass% based on the oxide₂：25～40％、CaO：0～5％、SrO：3～10％、BaO：5～15％、Li₂O：4～8％、Na₂O：0.3～3％、RO＞2×R’₂O、Li₂O/R’₂O：0.65～0.95、TiO₂：3～15％、ZrO₂：3～8％、Nb₂O₅: 10 to 30% of a high refractive index glass composition.

(3) As P₂O₅The system may, for example, contain P₂O₅: 10 to 70 mass% of Nb as a high refractive index component₂O₅、Ta₂O₅、Li₂O、SrO、BaO、TiO₂、ZrO₂、WO₃、Bi₂O₃、TeO₂And Ln₂O₃(Ln is at least 1 selected from Y, La, Gd, Yb and Lu): more than 1% of glass.

P₂O₅Is a glass-forming component constituting the glass, and has a large effect of imparting manufacturable stability to the glass and reducing the glass transition temperature and the liquid phase temperature. However, if P₂O₅When the content of (b) is less than 10% based on 100% of the total of the mother components, a sufficient effect cannot be obtained. P₂O₅The content of (b) is preferably 12% or more, preferably 15% or more, more preferably 20% or more, further preferably 30% or more, and particularly preferably 40% or more. In addition, if P₂O₅When the content of (b) is 70% or less, good chemical durability is obtained. P₂O₅The content of (b) is preferably 65% or less, more preferably 60% or less, still more preferably 55% or less, and particularly preferably 50% or less.

The high refractive index component and the above-mentioned (2) SiO₂Since the glass is the same, redundant description is omitted.

The compositions and properties of the glasses used in the present invention are shown in table 1. Table 1 shows the SiO₂Is a glass of composition. The physical properties of each glass in table 1 are values measured by the above-described method, and the devitrification viscosity is a value obtained by measuring the viscosity of the glass at the devitrification temperature with a rotational viscometer.

[ Table 1]

< anti-reflection film >

The antireflection film-equipped glass substrate of the present invention has an antireflection film on at least one main surface of the glass substrate. The antireflection film may be provided on only one main surface of the glass substrate, or may be provided on both main surfaces. The strength of the glass substrate varies depending on various factors, but also varies depending on the important refractive index in the present invention. Generally, if the refractive index of glass is high, the strength tends to decrease. However, in the present invention, the glass substrate having a refractive index of 1.68 or more is coated with the antireflection film, and the glass substrate with the antireflection film can be made stronger than the glass substrate alone. In particular, the strength can be adjusted to a preferable strength by controlling the film hardness.

The material of the antireflection film is not particularly limited, and various materials can be used as long as the material can suppress reflection of light. For example, an antireflection film formed of a single layer of a material having a lower refractive index than the glass substrate can be used as the antireflection film. By forming the high refractive index film and the low refractive index film alternately, lower reflectivity can be achieved. The high refractive index film herein means a film having a refractive index of 1.9 or more at a wavelength of 550nm, and the low refractive index layer film means a film having a refractive index of 1.6 or less at a wavelength of 550 nm.

The high refractive index film and the low refractive index film may be configured to include 1 layer, or may be configured to include 2 or more layers. When the high refractive index film and the low refractive index film each include 2 or more layers, the high refractive index film and the low refractive index film are preferably alternately laminated. The antireflection film may have a medium refractive index film having a refractive index of more than 1.6 and less than 1.9 at a wavelength of 550nm, in addition to the high refractive index film and the low refractive index film.

In particular, in order to improve the antireflection performance, the antireflection film is preferably a laminate in which a plurality of layers are laminated, and for example, the laminate is preferably a laminate in which 2 to 8 layers, more preferably 2 to 6 layers, are laminated as a whole. The laminate here is preferably a laminate in which a high refractive index film and a low refractive index film are laminated as described above, and the total number of layers of the high refractive index layer and the low refractive index layer is preferably in the above range.

Examples of the material of the high refractive index film include oxides of indium, zirconium, cerium, titanium, tantalum, niobium, tin, and the like. Specifically, In can be used₂O₃、ZrO₂、CeO₂、TiO₂、Ta₂O₅、Nb₂O₅SnO, etc.

As a material of the low refractive index film, silicon dioxide, aluminum, or nickel oxide (SiO) can be used₂、Al₂O₃NiO, etc.), fluorides of calcium, magnesium or yttrium (MgF)₂、CaF₂、Y₂O₃Etc.), magnesium sulfide (MgS)₂Etc.).

The materials of the high refractive index film and the low refractive index film may be used by appropriately selecting 1 or 2 or more of the above materials so that the respective refractive indices are within the above preferred ranges. If the high refractive index film and the low refractive index film are in the above-mentioned refractive index ranges, additives may be contained. Further, a film having a desired refractive index can be formed by mixing and using a material for the high refractive index film and a material for the low refractive index film at a predetermined ratio. In addition, the material of the medium refractive index film may be used by appropriately selecting, for example, 1 or 2 or more of the above materials so that the refractive index thereof is within the above-described preferable range.

Among them, from the viewpoint of productivity and the degree of refractive index, the high refractive index film is more preferably a film composed of 1 or more selected from titanium oxide, niobium oxide and tantalum oxide, and the low refractive index film is preferably a film composed of 1 or more selected from silicon oxide, aluminum oxide and magnesium oxide.

The thickness of the antireflection film is preferably 0.01 to 3 μm. This can realize the above-mentioned surface strength and film hardness, and can impart excellent strength to the glass substrate with the antireflection film. When the antireflection film is provided on both main surfaces of the antireflection film-equipped glass substrate of the present invention, the total thickness of the antireflection films on both main surfaces is preferably within the above range.

The antireflection film can be formed by a vacuum deposition method, an ion-assisted vapor deposition method using plasma, a sputtering method, an ion beam sputtering method, an ion plating method, or the like.

The vacuum deposition method is a method of laminating a film material on a lens or a substrate by evaporating the film material in a vacuum using resistance heating, electron gun heating, high-frequency induction heating, or the like, for example, using a vacuum chamber. The ion-assisted vapor deposition method is a method in which atoms and molecules of a film material evaporated by resistance heating, electron gun heating, or high-frequency induction heating are physically adsorbed on a substrate, and the atoms and molecules of the film material are more energetically activated by irradiating the substrate with ions using an ion gun. For example, when the vapor deposition method is used, a glass substrate is deposited while being held by a rotating drum and rotated, and a more uniform film is obtained. The glass substrate is preferably heated by a sheath heater or the like.

The film thickness of the film formed by vapor deposition can be measured by a crystal oscillation film thickness monitor or the like. In the vapor deposition method, the film hardness can be adjusted by, for example, a film formation temperature (temperature of the substrate), resistance heating, an output power of an electron gun (film formation power), an air pressure in a vacuum chamber, or the like. In the ion-assisted vapor deposition method, the film hardness may be adjusted by adjusting the irradiation amount of ions irradiated from an ion gun.

As a film formation method using plasma, an ion plating method is a method in which atoms and molecules of a film material evaporated by resistance heating, electron gun heating, or high-frequency induction heating are ionized by plasma, and an electric field is applied to cause the ions to collide with a substrate.

The sputtering method is a method of causing particles having energy of several hundred eV to several tens keV to collide with target atoms and sputtering the target atoms to transport the atoms to a substrate or a lens. The sputtering method generally has an advantage of easily forming a film having a higher density than that of the vacuum deposition method and an advantage of having high adhesion between the film and the substrate and the lens. When the antireflection film is formed by sputtering, the film hardness can be adjusted by the film forming conditions.

Among them, in order to obtain desired optical characteristics (controllability), film hardness, and durability, it is preferable to use a vacuum deposition method, an ion-assisted vapor deposition method, or a sputtering method.

[ method for producing anti-reflection film-coated glass substrate ]

The glass substrate used for the anti-reflection film-equipped glass substrate of the present invention is produced, for example, as follows. That is, first, the raw materials are weighed in the above-described predetermined glass composition and uniformly mixed. The prepared mixture was put into a platinum crucible, a quartz crucible, or an alumina crucible to be roughly melted. Thereafter, the resulting mixture is placed in a gold crucible, a platinum alloy crucible, a reinforced platinum crucible, or an iridium crucible, melted at a temperature of 1200 to 1400 ℃ for 2 to 10 hours, homogenized by defoaming, stirring, or the like, defoamed, or the like, and then cast into a mold and slowly cooled. Thereby obtaining glass.

Then, the glass is melted, and the molten glass is formed into a plate shape by a forming method such as a float method, a melting method, or a roll (roll) method, thereby obtaining a glass substrate.

The residual bubbles in the glass produced as described above are preferably 10 bubbles per 1kg (10 bubbles per kg) or less, more preferably 7 bubbles per kg or less, still more preferably 5 bubbles per kg or less, and particularly preferably 3 bubbles per kg or less. When the glass substrate is molded by the above method, if the residual bubbles are 10 bubbles/kg or less, the glass substrate containing no bubbles can be efficiently molded. When the diameter of the circle of the smallest dimension containing residual bubbles inside is defined as each size of the residual bubbles, each size of the residual bubbles is preferably 80 μm or less, more preferably 60 μm or less, still more preferably 40 μm or less, and particularly preferably 20 μm or less.

The diameter is defined as the longitudinal length L of the residual bubbles₁The length of the straight line of the maximum length of the residual bubbles on the straight line perpendicularly intersecting the diameter is set as the length L of the residual bubbles in the transverse direction₂When the shape of the remaining bubble is expressed by the aspect ratio, L₂/L₁Preferably 0.90 or more, more preferably 0.92 or more, and still more preferably 0.95 or more. If L is₂/L₁If the residual bubble content is 0.90 or more, the residual bubble is in a state close to a perfect circle (perfect sphere), and even if the residual bubble is contained, for example, the strength of the glass can be suppressed from being lowered as compared with the elliptical residual bubble, and the generation of cracks starting from the residual bubble can be suppressed when the glass substrate is produced. Even if the glass substrate has residual bubbles, the glass substrate has an effect of suppressing anisotropic scattering of light incident on the glass substrate, as compared with elliptical residual bubbles. The size and shape of the residual bubbles can be obtained from the values measured by a laser microscope (product of KEYENCE GmbH: VK-X100).

Next, an antireflection film is formed on at least one main surface of the glass substrate obtained above by the above-described vapor deposition method, sputtering method, or the like, to obtain an antireflection film-coated glass substrate.