alkali-free glass

Abstract

An object of the present application is to provide a glass which can suppress deformation of a glass substrate, is excellent in moldability, and has a low burden on manufacturing equipment. The alkali-free glass of the present application has a coefficient of thermal expansion, a Young's modulus, a strain point, a viscosity of 10 4 dPa s at a temperature T4, a glass surface devitrification temperature, and a viscosity of 10 2 dPa s at a temperature T2 within a prescribed range, and a content of SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO, MgO+CaO+SrO+BaO, and MgO / CaO within prescribed ranges.

Description

[0001] This application is a divisional application of the application filed on March 13, 2019, application number 201980018232.0, titled "Alkali-free glass". TECHNICAL FIELD

[0002] The present application relates to an alkali-free glass which is suitable as a glass substrate for various displays, photomasks, electronic device supports, information recording media, planar antennas, and the like. BACKGROUND

[0003] For a glass used in a glass plate (glass substrate) for various displays, photomasks, electronic device supports, information recording media, planar antennas, and the like, and in particular, a glass plate in which a thin film of metal or oxide, or the like, is formed on the surface, the following (1) to (4) and the like are required.

[0004] (1) When the glass contains an alkali metal oxide, alkali metal ions diffuse into the thin film described above and deteriorate the film properties of the thin film, and therefore the glass should substantially not contain alkali metal ions.

[0005] (2) When the glass plate is exposed to high temperatures in a thin film forming process, in order to be able to minimize the deformation of the glass plate and the shrinkage (thermal shrinkage) accompanying the stabilization of the structure of the glass, the strain point should be high.

[0006] (3) Sufficient chemical durability against various reagents used in semiconductor formation. In particular, durability against buffered hydrofluoric acid (BHF: a mixed solution of hydrofluoric acid and ammonium fluoride) used for etching of SiO x , SiN x , a drug solution containing hydrochloric acid used for etching of ITO, various acids (nitric acid, sulfuric acid, and the like) and alkalis of etchant stripping solution used for etching of metal electrodes, and the like.

[0007] (4) No defects (bubbles, streaks, inclusions, pits, scratches, and the like) in the interior and the surface.

[0008] In addition to the above requirements, in recent years, the following (5) to (9) have further been required.

[0009] (5) A glass with a small specific gravity is desired due to the demand for lightening of displays.

[0010] (6) Thinning of the glass plate is desired due to the demand for lightening of displays.

[0011] (7) Since a polycrystal silicon (p-Si) type liquid crystal display, which has a higher heat treatment temperature than the prior amorphous silicon (a-Si) type liquid crystal display (heat treatment temperature of a-Si: about 350°C, heat treatment temperature of p-Si: 350 to 550°C), is also produced, heat resistance is required.

[0012] (8) In order to accelerate the temperature rising and falling speed of heat treatment at the time of production of a liquid crystal display to improve productivity, or to improve heat shock resistance, a glass having a smaller average thermal expansion coefficient is required. On the other hand, if the average thermal expansion coefficient of the glass is too small, and various film forming processes such as a gate metal film, a gate insulating film, and the like at the time of production of a liquid crystal display are increased, there are problems that the warpage of the glass becomes large, defects such as cracks or scratches occur at the time of conveyance of the liquid crystal display, the shift of an exposure pattern becomes large, and the like.

[0013] (9) In addition, along with the large size and thinning of a glass substrate, a glass having a higher elastic modulus (Young's modulus / density) is required.

[0014] In order to satisfy the requirements as described above, various glass compositions have been proposed so far, for example, in a glass for a liquid crystal display panel (see Patent Documents 1 to 4).

[0015] Prior Art Documents

[0016] Patent Documents

[0017] Patent Document 1: Japanese Patent No. 5702888

[0018] Patent Document 2: International Publication No. 2013 / 183626

[0019] Patent Document 3: Japanese Patent No. 5849965

[0020] Patent Document 4: Japanese Patent No. 5712922 SUMMARY

[0021] In recent years, further high resolution of electronic displays is continuously developed, and in large televisions, along with high definition, the film thickness of, for example, Cu wiring is increased, and the like, and the warpage of a substrate due to various film formation easily becomes large. Therefore, the demand for a substrate having less warpage is continuously increased, and in order to satisfy the demand, it is necessary to make the Young's modulus of the glass higher.

[0022] However, the known glass having a high Young's modulus as described in Patent Documents 3 and 4 has a tendency that the strain point is high, and the devitrification temperature is higher than the temperature T4 at which the viscosity becomes 10 4 dPa-s. As a result, the molding of the glass becomes difficult, the load on the manufacturing equipment becomes large, and thus it is likely to cause an increase in production cost.

[0023] An object of the present application is to provide a glass which is excellent in moldability and has low burden on manufacturing equipment, and which can suppress deformation such as warpage of a glass substrate.

[0024] The average coefficient of thermal expansion of the alkali-free glass of the present application is 30 x 10 －7 43 x 10 －7 / °C in the range of 50 to 350°C, the Young's modulus is 88 GPa or more, the strain point is 650 to 725°C, the viscosity becomes 10 4 dPa-s at a temperature T4 of 1290°C or less, the devitrification temperature (T c ) of the glass surface is T4 + 20°C or less, the viscosity becomes 10 2 dPa-s at a temperature T2 of 1680°C or less,

[0025] contains 62 to 67% of SiO2, 12.5 to 16.5% of Al2O3, 0 to 3% of B2O3, 8 to 13% of MgO, 6 to 12% of CaO, 0.5 to 4% of SrO, and 0 to 0.5% of BaO, and MgO + CaO + SrO + BaO is 18 to 22%, and MgO / CaO is 0.8 to 1.33.

[0026] In one embodiment of the alkali-free glass of the present application, the specific elastic modulus can be 34 MN-m / kg or more.

[0027] In one embodiment of the alkali-free glass of the present application, the density can be 2.60 g / cm 3 or more.

[0028] In one embodiment of the alkali-free glass of the present application, the devitrification viscosity (η c ) of the glass surface can be 10 3.8 dPa-s or more.

[0029] In one embodiment of the alkali-free glass of the present application, the glass transition temperature can be 730 to 790°C.

[0030] In one embodiment of the alkali-free glass of the present application, the value represented by the following formula (I) can be 4.10 or more.

[0031] (7.87 [Al2O3] - 8.5 [B2O3] + 11.35 [MgO] + 7.09 [CaO] + 5.52 [SrO] - 1.45 [BaO]) / [SiO2]... Formula (I)

[0032] In one embodiment of the alkali-free glass of the present application, the value represented by the following formula (II) can be 0.95 or more.

[0033] (-1.02[Al203] + 10.79[B203] + 2.84[MgO] + 4.12[CaO] + 5.19[SrO] + 3.16[BaO]) / [Si02]... (II)

[0034] In one embodiment of the alkali-free glass of the present application, the value represented by the following formula (III) can be 5.5 or less.

[0035] (8.9[Al203] + 4.26[B203] + 11.3[MgO] + 4.54[CaO] + 0.1[SrO] - 9.98[BaO]) x {1 + ([MgO] / [CaO] - 1) 2} / [Si02]... (III)

[0036] In one embodiment of the alkali-free glass of the present application, it can contain 0.5% or less of Sn02, in terms of mol% on an oxide basis.

[0037] In one embodiment of the alkali-free glass of the present application, the β-OH value can be 0.05 to 0.5 mm －1 .

[0038] In one embodiment of the alkali-free glass of the present application, the shrinkage can be 100 ppm or less.

[0039] In one embodiment of the alkali-free glass of the present application, the equivalent cooling rate can be 5 to 500°C / minute.

[0040] One embodiment of the alkali-free glass of the present application can be a glass sheet of which at least one side is 1800 mm or more and the thickness is 0.7 mm or less.

[0041] One embodiment of the alkali-free glass of the present application is manufactured by a float method or a fusion method.

[0042] In addition, the display panel of the present application has the alkali-free glass of the present application.

[0043] In addition, the semiconductor device of the present application has the alkali-free glass of the present application.

[0044] In addition, the information recording medium of the present application has the alkali-free glass of the present application.

[0045] In addition, the planar antenna of the present application has the alkali-free glass of the present application.

[0046] According to the present application, it is possible to provide a glass which can suppress deformation such as warping of a glass substrate and is excellent in moldability and has a low burden on manufacturing equipment. DETAILED DESCRIPTION

[0047] Hereinafter, the embodiments of the present application will be described. It should be noted that the present application is not limited to the embodiments described below.

[0048] Hereinafter, the composition range of each component of the glass is expressed in terms of mol% on an oxide basis.

[0049] Hereinafter, the numerical range expressed by "numerical value A to numerical value B" means a range including numerical value A and numerical value B as the minimum value and the maximum value, respectively, and indicates a value of numerical value A or more and numerical value B or less.

[0050] First, the composition of the alkali-free glass of the present embodiment will be described.

[0051] When the content of SiO2 is less than 62 mol% (hereinafter, abbreviated as %), there is a tendency that the strain point does not sufficiently increase and the average coefficient of thermal expansion increases, and the specific gravity rises. Therefore, the content of SiO2 is 62% or more, preferably 62.5% or more, more preferably 63% or more, particularly preferably 63.5% or more, and most preferably 64% or more.

[0052] When the content of SiO2 exceeds 67%, there is a tendency that the melting property of the glass decreases, the Young's modulus decreases, and the devitrification temperature rises. Therefore, the content of SiO2 is 67% or less, preferably 66.5% or less, further preferably 66% or less, particularly preferably 65.7% or less.

[0053] Al2O3 increases the Young's modulus to suppress flexure, and suppresses the phase separation of the glass to increase the fracture toughness value to increase the strength of the glass. When the content of Al2O3 is less than 12.5%, it is difficult to exhibit these effects, and other components that increase the average coefficient of thermal expansion increase relatively, and therefore, there is a tendency that the average coefficient of thermal expansion increases. Therefore, the content of Al2O3 is 12.5% or more, preferably 12.8% or more, and more preferably 13% or more.

[0054] When the content of Al2O3 exceeds 16.5%, the melting property of the glass can deteriorate, the strain point rises, and the devitrification temperature rises. Therefore, the content of Al2O3 is 16.5% or less, preferably 16% or less, more preferably 15.7% or less, further preferably 15% or less, particularly preferably 14.5% or less, and most preferably 14% or less.

[0055] B2O3 is not an essential component, but improves the BHF resistance, and makes the melting reactivity of the glass good to lower the devitrification temperature, and therefore, can be contained at 3% or less. The content of B2O3 is 3% or less, preferably 2.5% or less, more preferably 2.2% or less, further preferably 2% or less, particularly preferably 1.7% or less, and most preferably 1.5% or less.

[0056] MgO increases the Young's modulus without increasing the specific gravity, and thus increases the specific elastic modulus to suppress the flexure, and increases the fracture toughness to increase the glass strength. In addition, MgO increases the melting property. If the content of MgO is less than 8%, it is difficult to exhibit these effects, and there is a possibility that the coefficient of thermal expansion becomes too low. Therefore, the content of MgO is 8% or more, preferably 8.2% or more, more preferably 8.5% or more.

[0057] However, if the content of MgO is too much, the devitrification temperature easily increases. Therefore, the content of MgO is 13% or less, preferably 12% or less, more preferably 11% or less, further preferably 10.5% or less, particularly preferably 10% or less, most preferably 9.7% or less.

[0058] CaO has a feature of increasing the specific elastic modulus next to MgO among the alkaline earth metals, without excessively lowering the strain point, and, like MgO, increases the melting property. In addition, CaO has a feature of not easily increasing the devitrification temperature, compared with MgO. If the content of CaO is less than 6%, it is difficult to exhibit these effects. Therefore, the content of CaO is 6% or more, preferably 7% or more, more preferably 8% or more, further preferably 9% or more.

[0059] If the content of CaO exceeds 12%, the average coefficient of thermal expansion becomes too high, and the devitrification temperature increases to easily devitrify at the time of manufacturing the glass. Therefore, the content of CaO is 12% or less, preferably 11% or less, more preferably 10% or less.

[0060] SrO increases the melting property without increasing the devitrification temperature of the glass, but if the content of SrO is less than 0.5%, it is difficult to exhibit this effect. Therefore, the content of SrO is 0.5% or more, preferably 1% or more, more preferably 1.2% or more, further preferably 1.5% or more.

[0061] The above effect of SrO is lower than that of BaO, and if the content of SrO is too much, the effect of increasing the specific gravity exceeds the above effect, and the average coefficient of thermal expansion can become too high. Therefore, the content of SrO is 4% or less, preferably 3% or less, more preferably 2.5% or less, further preferably 2% or less.

[0062] BaO is not an essential component, but increases the melting property without increasing the devitrification temperature of the glass, and thus can be contained in the alkali-free glass of the present embodiment. However, if the content of BaO is excessive, there is a tendency that the specific gravity becomes large, the Young's modulus decreases, and the average coefficient of thermal expansion becomes too high. Therefore, the content of BaO is 0.5% or less. The alkali-free glass of the present embodiment preferably substantially does not contain BaO.

[0063] Note that "substantially free of" in the present specification means free of except for unavoidable impurities mixed from raw materials and the like, i.e., not intentionally contained. In the present embodiment, the content of BaO when substantially free of BaO is, for example, 0.3% or less, preferably 0.2% or less, more preferably 0.1% or less, further preferably 0.05% or less, particularly preferably 0.01% or less.

[0064] If the total amount of the alkaline earth metal oxides, i.e., MgO + CaO + SrO + BaO (hereinafter, also referred to as "RO") is small, the devitrification temperature becomes high, i.e., the devitrification viscosity becomes low, and the moldability deteriorates. Therefore, RO is 18% or more.

[0065] If RO is too large, it is likely that the average coefficient of thermal expansion becomes large, and it is likely that the acid resistance becomes poor. Therefore, RO is 22% or less, preferably 21.5% or less, more preferably 21% or less, further preferably 20.7% or less, particularly preferably 20.5% or less, most preferably 20.3% or less.

[0066] In addition, if the ratio of the content of MgO with respect to the content of CaO, i.e., MgO / CaO is small, CaO-Al2O3-SiO2-based crystals become likely to precipitate, and thus the moldability deteriorates. Specifically, the devitrification temperature becomes high, i.e., the devitrification viscosity becomes low. Therefore, MgO / CaO is 0.8 or more, preferably 0.85 or more, more preferably 0.9 or more, further preferably 0.92 or more. However, if MgO / CaO is too large, MgO-Al2O3-SiO2-based crystals become likely to precipitate, the devitrification temperature becomes high, i.e., the devitrification viscosity becomes low. Therefore, MgO / CaO is 1.33 or less, preferably 1.3 or less, more preferably 1.25 or less, further preferably 1.2 or less, particularly preferably 1.1 or less, most preferably 1.05 or less.

[0067] The alkali-free glass of the present embodiment is substantially free of alkali metal oxides such as Li2O, Na2O, K2O, and the like. In the present embodiment, the total content of the alkali metal oxides when substantially free of alkali metal oxides is, for example, 0.5% or less, preferably 0.2% or less, more preferably 0.1% or less, more preferably 0.08% or less, further preferably 0.05% or less, most preferably 0.03% or less.

[0068] In order to prevent deterioration of the properties of a thin film of metal or oxide provided on the surface of the glass sheet when the non-alkali glass sheet is used for manufacturing a display, the non-alkali glass of the present embodiment preferably contains substantially no P2O5. In the present embodiment, the content of P2O5 when substantially no P2O5 is contained is, for example, 0.1% or less. Furthermore, in order to make recycling of the glass easy, the non-alkali glass of the present embodiment preferably contains substantially no PbO, As2O3, Sb2O3. In the present embodiment, the content of PbO, As2O3, Sb2O3 when substantially no PbO, As2O3, Sb2O3 is contained is, for example, 0.01% or less, and preferably 0.005% or less, respectively.

[0069] In order to improve the melting property, the fining property, the moldability, and the like of the glass, the non-alkali glass of the present embodiment can contain one or more of ZrO2, ZnO, Fe2O3, SO3, F, Cl, and SnO2 in a total amount of 2% or less, preferably 1% or less, and more preferably 0.5% or less.

[0070] F is a component that improves the melting property and the fining property of the glass. When the non-alkali glass of the present embodiment contains F, the content of F is preferably 1.5% or less (0.43% by mass or less).

[0071] SnO2 is also a component that improves the melting property and the fining property of the glass. When the non-alkali glass of the present embodiment contains SnO2, the content of SnO2 is preferably 0.5% or less (1.1% by mass or less).

[0072] The β-OH value of the non-alkali glass of the present embodiment is preferably 0.05 to 0.5 mm －1 .

[0073] The β-OH value is an index of the water content in the glass, and is obtained by dividing the maximum value β max of the absorbance of light having a wavelength of 2.75 to 2.95 μm by the thickness (mm) of the sample. If the β-OH value is 0.5 mm －1 or more, the shrinkage described later is easily achieved. The β-OH value is more preferably 0.45 mm －1 or more, and more preferably 0.4 mm －1 or more, and more preferably 0.35 mm －1 or more, and further preferably 0.3 mm －1 or more, and particularly preferably 0.28 mm －1 or more, and most preferably 0.25 mm －1 or more. On the other hand, if the β-OH value is 0.05 mm －1 or less, the strain point of the glass described later is easily achieved. The β-OH value is more preferably 0.08 mm －1 or more, and more preferably 0.1 mm－1 More preferably, the above is 0.13 mm －1 Particularly preferably, the above is 0.15 mm －1 Most preferably, the above is 0.18 mm －1 The above.

[0074] The alkali-free glass of the present embodiment is preferably 4.10 or greater in the value represented by the following formula (I).

[0075] (7.87 [Al203] - 8.5 [B203] + 11.35 [MgO] + 7.09 [CaO] + 5.52 [SrO] - 1.45 [BaO]) / [Si02]... Formula (I)

[0076] The value represented by formula (I) is an index of Young's modulus, and if the value is less than 4.10, the Young's modulus becomes low. In the alkali-free glass of the present embodiment, the value represented by formula (I) is more preferably 4.15 or greater, further preferably 4.2 or greater, particularly preferably 4.25 or greater, and most preferably 4.3 or greater.

[0077] Note that in the above formula (I), [Al203], [B203], [MgO], [CaO], [SrO], [BaO], and [Si02] each represent the content of Al203, B203, MgO, CaO, SrO, BaO, and Si02, respectively, in terms of mol% on an oxide basis. The same applies to the following formulas (II) and (III).

[0078] The alkali-free glass of the present embodiment is preferably 0.95 or greater in the value represented by the following formula (II).

[0079] (-1.02 [Al203] + 10.79 [B203] + 2.84 [MgO] + 4.12 [CaO] + 5.19 [SrO] + 3.16 [BaO]) / [Si02]... Formula (II)

[0080] The value represented by formula (II) is an index of strain point, and if the value is less than 0.95, the strain point becomes high. In the alkali-free glass of the present embodiment, the value represented by formula (II) is more preferably 1.0 or greater, further preferably 1.05 or greater, and particularly preferably 1.1 or greater.

[0081] The alkali-free glass of the present embodiment is preferably 5.5 or less in the value represented by the following formula (III).

[0082] (8.9 [Al203] + 4.26 [B203] + 11.3 [MgO] + 4.54 [CaO] + 0.1 [SrO] - 9.98 [BaO]) x {1 + ([MgO] / [CaO] - 1) 2} / [SiO2]... (III)

[0083] The value represented by formula (III) is an index of the glass surface devitrification viscosity (η c ) and if the value exceeds 5.5, the glass surface devitrification viscosity (η c ) becomes low. In the alkali-free glass of the present embodiment, the value represented by formula (III) is more preferably 5.1 or less, further preferably 4.8 or less, particularly preferably 4.5 or less, and most preferably 4.3 or less.

[0084] The average thermal expansion coefficient of the alkali-free glass of the present embodiment in the range of 50 to 350°C is 30 x 10 －7 / °C or more. For example, in the manufacture of a TFT-side substrate of a flat panel display, a gate metal film of copper or the like and a gate insulating film of silicon nitride or the like are sometimes sequentially layered on an alkali-free glass substrate. In this case, if the average thermal expansion coefficient in the range of 50 to 350°C is less than 30 x 10 －7 / °C, the difference in thermal expansion from the gate metal film of copper or the like formed on the surface of the substrate becomes large, and there is a possibility that problems such as warping of the substrate and generation of film peeling will occur.

[0085] The average thermal expansion coefficient in the range of 50 to 350°C is preferably 33 x 10 －7 / °C or more, more preferably 35 x 10 －7 / °C or more, further preferably 36 x 10 －7 / °C or more, particularly preferably 37 x 10 －7 / °C or more, and most preferably 38 x 10 －7 / °C or more.

[0086] On the other hand, if the average thermal expansion coefficient in the range of 50 to 350°C exceeds 43 x 10 －7 / °C, there is a possibility that cracks will occur in the glass during the manufacturing process of a product such as a display. Therefore, the average thermal expansion coefficient in the range of 50 to 350°C is 43 x 10 －7 / °C or less.

[0087] The average thermal expansion coefficient in the range of 50 to 350°C is preferably 42 x 10 －7 / °C or less, more preferably 41.5 x 10 －7 / °C or less, further preferably 41 x 10 －7 / °C or less, particularly preferably 40.5 x 10 －7 / °C or less, and most preferably 40.3 x 10 －7 / °C or less.

[0088] In addition, the Young's modulus of the non-alkali glass according to the present embodiment is 88 GPa or more. Thus, deformation of the substrate due to external stress is suppressed. For example, substrate warping can be suppressed when a film is formed on the surface of the glass substrate. As a specific example, warping of the substrate is suppressed when a gate metal film of copper or the like, and a gate insulating film of silicon nitride or the like are formed on the surface of the substrate in the manufacture of a TFT-side substrate of a flat panel display. In addition, for example, flexing when the size of the substrate is increased is also suppressed. The Young's modulus is preferably 88.5 GPa or more, more preferably 89 GPa or more, further preferably 89.5 GPa or more, particularly preferably 90 GPa or more, and most preferably 90.5 GPa or more. The Young's modulus can be measured by an ultrasonic method.

[0089] The strain point of the non-alkali glass according to the present embodiment is 650 to 725°C. If the strain point is less than 650°C, deformation of the glass sheet and shrinkage (thermal shrinkage) accompanying stabilization of the structure of the glass are easily caused when the glass sheet is exposed to high temperatures in the thin film formation process of a display. The strain point is preferably 685°C or more, more preferably 690°C or more, further preferably 693°C or more, particularly preferably 695°C or more, and most preferably 698°C or more. On the other hand, if the strain point is too high, the temperature of the slow cooling device needs to be made higher in correspondence therewith, and there is a tendency for the life of the slow cooling device to decrease. The strain point is preferably 723°C or less, more preferably 720°C or less, further preferably 718°C or less, particularly preferably 716°C or less, and most preferably 714°C or less.

[0090] The viscosity of the non-alkali glass according to the present embodiment becomes 10 4 dPa s at a temperature T4 of 1290°C or less. Thus, the moldability of the non-alkali glass according to the present embodiment is excellent. In addition, for example, the temperature at the time of molding of the glass according to the present embodiment can be made lower to reduce the dispersing matter in the atmosphere around the glass, and thus defects can be reduced. Furthermore, the glass can be molded at a lower temperature, and thus the burden on the manufacturing equipment can be reduced. For example, the life of a floatation furnace or the like in which the glass is molded can be extended, and the productivity can be improved. T4 is preferably 1287°C or less, more preferably 1285°C or less, further preferably 1283°C or less, and particularly preferably 1280°C or less.

[0091] T4 can be measured as the temperature at which the viscosity becomes 10 4 dPa s by using a rotational viscometer according to the method prescribed in ASTM C 965-96. Note that, in the examples described later, NBS 710 and NIST 717a were used as reference samples for device calibration.

[0092] The glass surface devitrification temperature (T c) is T4 + 20°C or less. Thus, the moldability of the alkali-free glass of the present embodiment is excellent. In addition, thus, the generation of crystals in the interior of the glass during molding can be suppressed, and the transmittance can be reduced. In addition, the burden on the manufacturing equipment can be reduced. For example, the life of a floatation furnace or the like in which the glass is molded can be extended, and the productivity can be improved.

[0093] The glass surface devitrification temperature (T c ) is preferably T4 + 10°C or less, more preferably T4 + 5°C or less, further preferably T4°C or less, particularly preferably T4 - 1°C or less, and most preferably T4 - 5°C or less.

[0094] The glass surface devitrification temperature (T c ) and the glass interior devitrification temperature (T d ) can be obtained as follows. That is, glass particles after pulverization are put in a platinum dish, and heat treatment is performed for 17 hours in an electric furnace controlled to a certain temperature. After the heat treatment, using an optical microscope, the maximum temperature at which crystals are precipitated on the surface of the glass and the minimum temperature at which crystals are not precipitated are measured, and the average thereof is taken as the glass surface devitrification temperature (T c ). Similarly, the maximum temperature at which crystals are precipitated in the interior of the glass and the minimum temperature at which crystals are not precipitated are measured, and the average thereof is taken as the glass interior devitrification temperature (T d ). The viscosities at the glass surface devitrification temperature (T c ) and the glass interior devitrification temperature (T d ) are obtained by measuring the viscosities of the glass at each devitrification temperature.

[0095] The specific elastic modulus (Young's modulus (GPa) / density (g / cm 3 ) of the alkali-free glass of the present embodiment is preferably 34 MN m / kg or more. Thus, the self-weight deflection is small, and the handling at the time of large-sized substrate formation becomes easy. The specific elastic modulus is more preferably 34.5 MN m / kg or more, further preferably 34.8 MN m / kg or more, particularly preferably 35 MN m / kg or more, and most preferably 35.2 MN m / kg or more. Note that the large-sized substrate is, for example, a substrate of which at least one side is 1800 mm or more. The at least one side of the large-sized substrate can be, for example, 2000 mm or more, 2500 mm or more, 3000 mm or more, or 3500 mm or more.

[0096] The density of the alkali-free glass of the present embodiment is preferably 2.60 g / cm 3 or more. Thus, the self-weight deflection is small, and the handling at the time of large-sized substrate formation becomes easy. In addition, the device using the alkali-free glass of the present embodiment can be made light. The density is more preferably 2.59 g / cm 3The following is a further preferred value: 2.58 g / cm³ 3 The following is particularly preferred: 2.57 g / cm³ 3 The optimal value is 2.56 g / cm³. 3 the following.

[0097] The devitrification temperature (T) of the alkali-free glass in this embodiment is... c The viscosity at which the glass surface devitrifies (η) is measured, i.e., the viscosity at which the glass surface devit c ) Preferably 10 3.8 The viscosity is above dPa·s. Therefore, the formability of the glass substrate is excellent. Furthermore, this suppresses the formation of crystals within the glass during forming, thus preventing a decrease in transmittance. Additionally, this reduces the burden on manufacturing equipment. For example, it extends the lifespan of float glass furnaces used for forming glass substrates, thereby increasing productivity. The devitrification viscosity of the glass surface (η) c More preferably 10 3.85 dPa·s or higher, more preferably 10 3.9 dPa·s or higher, especially preferably 10 4 dPa·s or higher, with the optimal value being 10. 4.05 dPa·s or above.

[0098] In this embodiment, the viscosity of the alkali-free glass is 10. 2 The temperature T2, measured in dPa·s, is preferably 1680°C or lower. This results in excellent glass solubility. Furthermore, it reduces the burden on manufacturing equipment. For example, it extends the lifespan of furnaces used for melting glass and increases productivity. Additionally, it reduces defects from the furnace (e.g., pitting defects, Zr defects, etc.). T2 is more preferably 1670°C or lower, even more preferably 1660°C or lower, particularly preferably 1640°C or lower, especially preferably 1635°C or lower, and most preferably 1625°C or lower.

[0099] The glass transition temperature of the alkali-free glass in this embodiment is preferably 730 to 790°C. Setting the glass transition temperature to 730°C or higher results in excellent glass formability. For example, it can reduce thickness variations and surface irregularities. Furthermore, setting the glass transition temperature to 790°C or lower reduces the burden on manufacturing equipment. For example, it can lower the surface temperature of the rollers used to form the glass, extending equipment life and increasing productivity. A glass transition temperature of 740°C or higher is more preferred, further preferred to be 745°C or higher, particularly preferred to be 750°C or higher, and most preferably 755°C or higher. On the other hand, a glass transition temperature of 785°C or lower is more preferred, further preferred to be 783°C or lower, particularly preferred to be 780°C or lower, and most preferably 775°C or lower.

[0100] The non-alkali glass of the present embodiment preferably has a shrinkage of 100 ppm or less, more preferably 90 ppm or less, further preferably 80 ppm or less, further preferably 75 ppm or less, particularly preferably 70 ppm or less, and most preferably 65 ppm or less. The shrinkage refers to the thermal shrinkage of glass due to relaxation of the glass structure upon heat treatment. If the shrinkage is 100 ppm or less, the deformation of the glass and the dimensional change accompanying the stabilization of the structure of the glass can be suppressed to the minimum when the glass is exposed to high temperatures in the thin film formation process performed in the process of manufacturing various displays.

[0101] Note that the shrinkage in the present embodiment refers to the shrinkage measured in the following order.

[0102] A glass plate sample (a sample of 100 mm in length x 10 mm in width x 1 mm in thickness mirror-polished with cerium oxide) obtained by processing the non-alkali glass of the present embodiment was held at a temperature of the glass transition temperature + 120°C for 5 minutes, and then cooled to room temperature at 40°C per minute. After the glass plate sample was cooled to room temperature, the total length (lengthwise direction) LI of the sample was measured. Thereafter, the glass plate sample was heated to 600°C at 100°C per hour, held at 600°C for 80 minutes, and then cooled to room temperature at 100°C per hour. After the glass plate sample was cooled to room temperature, the total length L2 of the sample was measured again. The ratio of the difference between the total lengths before and after the heat treatment at 600°C (LI - L2) to the total length LI of the sample before the heat treatment at 600°C (LI - L2) / LI was taken as the value of the shrinkage.

[0103] In order to reduce the shrinkage, the non-alkali glass of the present embodiment is, for example, preferably made to have an equivalent cooling rate of 500°C / minute or less. From the viewpoint of the balance between the shrinkage and the productivity, the equivalent cooling rate is preferably 5°C / minute to 500°C / minute. From the viewpoint of the productivity, the equivalent cooling rate is more preferably 10°C / minute or more, further preferably 15°C / minute or more, particularly preferably 20°C / minute or more, and most preferably 25°C / minute or more. From the viewpoint of the shrinkage, the equivalent cooling rate is more preferably 300°C / minute or less, further preferably 200°C / minute or less, particularly preferably 150°C / minute or less, and most preferably 100°C / minute or less.

[0104] Note that the equivalent cooling rate in the present embodiment refers to the equivalent cooling rate measured in the following order.

[0105] Multiple 10mm × 10mm × 1mm cuboid samples for calibration curve preparation were prepared by processing the alkali-free glass of this embodiment. These samples were held at the glass transition temperature +120°C for 5 minutes using an infrared heating furnace. Subsequently, each sample was cooled to 25°C at different cooling rates ranging from 1°C / min to 1000°C / min. Next, using a precision refractometer KPR-2000 manufactured by Shimadzu Devices, the refractive index n of the d-line (wavelength 587.6nm) of these samples was measured using the V-block method. d The determination was performed. The n values ​​obtained from each sample were... d Plotting n relative to the logarithm of the cooling rate yields n. d Correction curve relative to cooling rate.

[0106] Next, the alkali-free glass of this embodiment was processed into a 10mm × 10mm × 1mm cuboid shape, and the n was measured using the V-block method with a precision refractometer KPR-2000 manufactured by Shimadzu Device. d The n obtained is derived from the above correction curve. d The corresponding cooling rate is taken as the equivalent cooling rate.

[0107] The alkali-free glass of this embodiment has a Young's modulus of 88 GPa or higher, which is relatively high. This suppresses deformation of the substrate caused by external stress, making it suitable as a glass plate for use as a large substrate. A large substrate refers to, for example, a glass plate with at least one side being 1800 mm or more; specifically, a glass plate with a long side of 1800 mm or more and a short side of 1500 mm or more.

[0108] The alkali-free glass of this embodiment is more preferably a glass plate with at least one side being 2400 mm or more, for example, a glass plate with a long side of 2400 mm or more and a short side of 2100 mm or more; more preferably a glass plate with at least one side being 3000 mm or more, for example, a glass plate with a long side of 3000 mm or more and a short side of 2800 mm or more; particularly preferably a glass plate with at least one side being 3200 mm or more, for example, a glass plate with a long side of 3200 mm or more and a short side of 2900 mm or more; most preferably a glass plate with at least one side being 3300 mm or more, for example, a glass plate with a long side of 3300 mm or more and a short side of 2950 mm or more.

[0109] The alkali-free glass of the present embodiment is preferably 0.7 mm or less in thickness because it is lightweight. The thickness of the alkali-free glass of the present embodiment is more preferably 0.65 mm or less, further preferably 0.55 mm or less, preferably 0.45 mm or less, and most preferably 0.4 mm or less. The thickness can be 0.1 mm or less or 0.05 mm or less, but is preferably 0.1 mm or more and more preferably 0.2 mm or more from the viewpoint of preventing self-weight deflection.

[0110] The alkali-free glass of the present embodiment can be produced, for example, in the following order.

[0111] The raw materials of the glass are prepared in such a manner as to become the desired glass composition, and are charged into a melting furnace and heated to 1500 to 1800°C to be melted to obtain a molten glass. The obtained molten glass is formed into a glass ribbon of a predetermined thickness by a forming device, and the glass ribbon is slowly cooled and then cut to thereby obtain an alkali-free glass.

[0112] Note that, in the production of the alkali-free glass of the present embodiment, cooling is preferably performed at an equivalent cooling rate of 500°C / min or less, for example, in order to reduce the shrinkage.

[0113] In the production of the alkali-free glass of the present embodiment, the molten glass is preferably formed into a glass sheet by a float method or a fusion method. The float method is preferably used from the viewpoint of stably producing a large-sized sheet glass (for example, 1800 mm or more on one side) having a high Young's modulus.

[0114] Next, the display panel of the present embodiment will be described.

[0115] The display panel of the present embodiment has the alkali-free glass of the present embodiment described above as a glass substrate. The display panel is not particularly limited as long as it has the alkali-free glass of the present embodiment, and can be various display panels such as a liquid crystal display panel, an organic EL display panel, and the like.

[0116] In the case of a thin film transistor liquid crystal display (TFT-LCD), for example, there are a display face electrode substrate (array substrate) in which a gate electrode line and an oxide layer for gate insulation are formed on the surface, and further a pixel electrode is formed on the surface of the oxide layer, and a color filter substrate in which a color filter of RGB and a counter electrode are formed on the surface, and a liquid crystal material is interposed between the array substrate and the color filter substrate to constitute a liquid crystal display cell. The liquid crystal display panel includes other elements such as a peripheral circuit in addition to the liquid crystal display cell. The liquid crystal display panel of the present embodiment uses the alkali-free glass of the present embodiment for at least one of the pair of substrates constituting the liquid crystal display cell.

[0117] The non-alkali glass of the present embodiment can be used, for example, as a glass sheet for supporting electronic devices. When the non-alkali glass of the present embodiment is used as a glass sheet for supporting electronic devices, a device forming substrate such as a glass substrate, a silicon substrate, a resin substrate, or the like is attached to the non-alkali glass (glass sheet for supporting electronic devices) directly or using an adhesive material to support the device forming substrate. As a glass sheet for supporting electronic devices, for example, a glass sheet for supporting used in the manufacturing process of a flexible display (for example, an organic EL display) having a resin such as polyimide as a substrate, a glass sheet for supporting a resin-silicon chip composite wafer used in the semiconductor package manufacturing process, or the like can be cited.

[0118] Next, the semiconductor device of the present embodiment will be described.

[0119] The semiconductor device of the present embodiment has the non-alkali glass of the present embodiment described above as a glass substrate. The semiconductor device of the present embodiment, specifically, for example, has the non-alkali glass of the present embodiment as a glass substrate for an image sensor such as MEMS, CMOS, CIS, or the like. In addition, the semiconductor device of the present embodiment has the non-alkali glass of the present embodiment as a cover glass for a display device for projection use, for example, a cover glass for LCOS (Liquid Cristyal ON Silicon).

[0120] Next, the information recording medium of the present embodiment will be described.

[0121] The information recording medium of the present embodiment has the non-alkali glass of the present embodiment described above as a glass substrate. As an information recording medium, specifically, for example, a magnetic recording medium, an optical disc can be cited. As a magnetic recording medium, for example, an energy-assisted type magnetic recording medium, a perpendicular magnetic recording type magnetic recording medium can be cited.

[0122] Next, the planar antenna of the present embodiment will be described.

[0123] The planar antenna of the present embodiment has the non-alkali glass of the present embodiment described above as a glass substrate. As the planar antenna of the present embodiment, specifically, as an antenna having good directivity and reception sensitivity, for example, a liquid crystal antenna, a microstrip antenna (block antenna) such as a planar liquid crystal antenna having a planar shape can be cited. The liquid crystal antenna is disclosed, for example, in International Publication No. 2018 / 016398. The block antenna is disclosed, for example, in Japanese Laid-Open No. 2017-509266, Japanese Laid-Open No. 2017-063255.

[0124] Example

[0125] Hereinafter, although the embodiments are described, the present application is not limited to these embodiments. Hereinafter, Examples 1 to 12 and Examples 19 to 36 are embodiments, and Examples 13 to 18 are comparative examples.

[0126] Each component was prepared by adjusting the raw materials in the composition shown in Tables 1 to 6 (unit: mol%) as a glass composition, and melted at 1600°C for 1 hour using a platinum crucible. After melting, the molten liquid was discharged onto a carbon plate, and held at a temperature of the glass transition temperature + 30°C for 60 minutes, and then cooled to room temperature (25°C) at 1°C per minute to obtain a plate-shaped glass. This was mirror-polished to obtain a glass plate, and various physical properties were measured. The results are shown in Tables 1 to 6. Note that in Tables 1 to 6, the values shown in parentheses are calculated values, and the blank cells are not measured.

[0127] Hereinafter, the measurement methods of each property are shown.

[0128] (Average thermal expansion coefficient)

[0129] This was measured using a differential thermal dilatometer (TMA) according to the method prescribed in JIS R3102 (1995). The measurement temperature range was room temperature to 400°C or higher, and the average thermal expansion coefficient from 50 to 350°C was expressed in units of 10 －7 / °C.

[0130] (Density)

[0131] The density of a glass ingot of about 20 g containing no bubbles was measured by the Archimedes method according to the method prescribed in JIS Z 8807.

[0132] (Strain point)

[0133] The strain point was measured by the fiber elongation method according to the method prescribed in JIS R3103-2 (2001).

[0134] (Glass transition temperature Tg)

[0135] The glass transition temperature Tg was measured by the thermal expansion method according to the method prescribed in JIS R3103-3 (2001).

[0136] (Young's modulus)

[0137] The Young's modulus was measured by the ultrasonic pulse method according to the method prescribed in JIS Z 2280 for a glass having a thickness of 0.5 to 10 mm.

[0138] (T2)

[0139] The viscosity was measured using a rotational viscometer according to the method prescribed in ASTM C 965-96 for a glass having a thickness of 10 2The temperature T2 (°C) at which the viscosity is d Pa s is measured.

[0140] (T4)

[0141] The viscosity is measured using a rotational viscometer according to the method prescribed in ASTM C 965-96, and the viscosity at 10 4 The temperature T4 (°C) at which the viscosity is d Pa s is measured.

[0142] (Tg)

[0143] The glass is crushed and classified using a test sieve so as to have a particle size in the range of 2 to 4 mm. The resulting glass chips are ultrasonically washed in isopropyl alcohol for 5 minutes, washed with ion-exchange water, and then dried and placed in a platinum dish and heat-treated in an electric furnace controlled to a constant temperature for 17 hours. The heat-treatment temperature is set at 10 °C intervals.

[0144] After heat-treatment, the glass is removed from the platinum dish and an optical microscope is used to measure the maximum temperature at which crystals precipitate on the surface and inside of the glass and the minimum temperature at which no crystals precipitate.

[0145] The maximum temperature at which crystals precipitate on the surface and inside of the glass and the minimum temperature at which no crystals precipitate are each measured once (two measurements are difficult to judge when crystals precipitate).

[0146] The average of the maximum temperature at which crystals precipitate on the surface of the glass and the minimum temperature at which no crystals precipitate is taken as the surface devitrification temperature (T c ) of the glass. Similarly, the average of the maximum temperature at which crystals precipitate inside the glass and the minimum temperature at which no crystals precipitate is taken as the inside devitrification temperature (T d ) of the glass.

[0147] Specific elastic modulus

[0148] The specific elastic modulus is obtained by dividing the Young's modulus obtained by the foregoing procedure by the density.

[0149] Devitrification viscosity

[0150] The surface devitrification temperature (T c ) of the glass is obtained by the foregoing method, the viscosity of the glass at the surface devitrification temperature (T c ) of the glass is measured, and this is taken as the surface devitrification viscosity (η c ) of the glass. Similarly, the inside devitrification temperature (T d ) of the glass is obtained, the viscosity of the glass at the inside devitrification temperature (T d ) of the glass is measured, and this is taken as the inside devitrification viscosity (η d ) of the glass.

[0151] [Table 1]

[0152]

[0153] [Table 2]

[0154]

[0155] [Table 3]

[0156]

[0157] [Table 4]

[0158]

[0159] [Table 5]

[0160]

[0161] [Table 6]

[0162]

[0163] The Young's modulus of Example 13, in which Al2O3 is less than 12.5%, B2O3 is more than 3%, MgO is less than 8%, CaO is less than 6%, SrO is more than 4%, RO is less than 18, and MgO / CaO is more than 1.33, is low, less than 88 GPa, and T4 is high, more than 1290°C. The glass surface devitrification temperature (Tg) of Example 14, in which Al2O3 is less than 12.5% and SrO is 0%, is higher than T4+20°C. c The strain point of Examples 15, 17, and 18, in which the value of Formula (II) is less than 0.95, is high, more than 725°C. The average coefficient of thermal expansion of Example 16, in which SiO2 is less than 62%, Al2O3 is less than 12.5%, MgO is more than 13%, CaO is more than 12%, SrO is 0%, and RO is more than 22, is large, more than 43x10 －7 / °C.

[0164] The present application has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications will be evident to those skilled in the art without departing from the spirit and scope of the application. It should be noted that this application is based on Japanese Patent Application (Japanese Patent Application No. 2018-46960) filed on March 14, 2018, the entire contents of which are hereby incorporated by reference. In addition, all the references cited herein are incorporated by reference in their entireties.

[0165] Industrial Applicability

[0166] The alkali-free glass of the present application having the above-described characteristics is suitable for use in substrates for displays, substrates for photomasks, substrates for supporting electronic devices, substrates for information recording media, substrates for planar antennas, and the like.

Claims

1. An alkali-free glass having an average coefficient of thermal expansion of 30 x 10 －7 43 x 10 － 7 / °C in the range of 50 to 350°C, a Young's modulus of 88 GPa or more, a strain point of 650 to 725°C, a temperature T4 at which the viscosity becomes 10 4 dPa-s of 1290°C or less, a glass surface devitrification temperature T c of T4 + 20°C or less, a temperature T2 at which the viscosity becomes 10 2 dPa-s of 1680°C or less. containing Al2O3 and B2O3, contains 62 to 67% of SiO2, 12.5 to 16.5% of Al2O3, 0 to 3% of B2O3, 9 to 13% of MgO, 6 to 12% of CaO, 0.5 to 2.5% of SrO, 0 to 0.5% of BaO, and MgO + CaO + SrO + BaO is 18 to 22%, and MgO / CaO is 1.1 to 1.33, in terms of mol% on an oxide basis, the value represented by the following formula (II) is 1.06 to 1.32, (-1.02[Al2O3] + 10.79[B2O3] + 2.84[MgO] + 4.12[CaO] + 5.19[SrO] + 3.16[BaO]) / [SiO2]... Formula (II) the value represented by the following formula (III) is 4.09 to 4.8, (8.9[Al203] + 4.26[B203] + 11.3[MgO] + 4.54[CaO] + 0.1[SrO] - 9.98[BaO]) x {1 + ([MgO] / [CaO] - 1)} / [Si02]... (III) 2 (8.9[Al203] + 4.26[B203] + 11.3[MgO] + 4.54[CaO] + 0.1[SrO] - 9.98[BaO]) x {1 + ([MgO] / [CaO] - 1)} / [Si02]...

2. The alkali-free glass according to claim 1, wherein, the value represented by the following formula (I) is 4.10 to 4.6, (7.87[Al2O3] - 8.5[B2O3] + 11.35[MgO] + 7.09[CaO] + 5.52[SrO] - 1.45[BaO]) / [SiO2]... Formula (I).

3. The alkali-free glass according to claim 1 or 2, wherein, Density 2.60 g / cm 3 The following.

4. The alkali-free glass according to claim 1 or 2, wherein, glass surface devitrification viscosity η c 10 3.8 dPa-s or more.

5. The alkali-free glass according to claim 1 or 2, wherein, the glass transition temperature is 730 to 790°C.

6. The alkali-free glass according to claim 1 or 2, wherein, the value represented by the formula (II) is 1.17 or more.

7. The alkali-free glass according to claim 1 or 2, wherein, the value represented by the formula (III) is 4.61 or less.

8. The alkali-free glass according to claim 1 or 2, wherein, contains 0.5% or less of SnO2, in terms of mol% on an oxide basis.

9. The alkali-free glass according to claim 1 or 2, wherein, β-OH values of 0.05 to 0.5 mm －1 .

10. The alkali-free glass according to claim 1 or 2, wherein, the shrinkage is 100 ppm or less.

11. The alkali-free glass according to claim 1 or 2, wherein, the equivalent cooling rate is 5 to 500°C / minute.

12. The alkali-free glass according to claim 1 or 2, wherein, is a glass sheet of which at least one side is 1800 mm or more and the thickness is 0.7 mm or less.

13. The alkali-free glass according to claim 12, wherein, is manufactured by a float method or a fusion method.

14. A display panel having the alkali-free glass according to any one of claims 1 to 13.

15. A semiconductor device having the alkali-free glass according to any one of claims 1 to 13.

16. An information recording medium having the alkali-free glass according to any one of claims 1 to 13.

17. A planar antenna having the alkali-free glass according to any one of claims 1 to 13.

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