WO2023053786A1 - Production method for strengthened glass - Google Patents

Production method for strengthened glass Download PDF

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Publication number
WO2023053786A1
WO2023053786A1 PCT/JP2022/031820 JP2022031820W WO2023053786A1 WO 2023053786 A1 WO2023053786 A1 WO 2023053786A1 JP 2022031820 W JP2022031820 W JP 2022031820W WO 2023053786 A1 WO2023053786 A1 WO 2023053786A1
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glass
tempered glass
stress layer
chemical strengthening
compressive stress
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PCT/JP2022/031820
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French (fr)
Japanese (ja)
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一嘉 中島
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日本電気硝子株式会社
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Publication of WO2023053786A1 publication Critical patent/WO2023053786A1/en

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C21/00—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface

Definitions

  • the present invention relates to a method for manufacturing tempered glass having a compressive stress layer.
  • glass products such as cover glass for smartphones and windshields of automobiles sometimes use tempered glass with a reinforced surface for the purpose of preventing cracking and improving mechanical strength.
  • tempered glass In such tempered glass, a compressive stress layer is formed on the surface of the glass by a method such as chemical strengthening treatment, thereby suppressing the occurrence of scratches and the extension of cracks.
  • An object of the present invention is to provide a method for producing tempered glass that can reliably and stably produce tempered glass having a compressive stress layer.
  • the method for producing tempered glass according to the present invention includes a forming step of obtaining tempered glass by thermoforming glass, and chemically tempering the tempered glass to obtain tempered glass having a compressive stress layer on the surface.
  • the tempered glass has a first main surface and a second main surface facing each other, and in the determining step, a compressive stress layer is formed on the first main surface of the tempered glass. and confirming that a tensile stress layer is formed on the second main surface, and the non-stress layer existing between the compressive stress layer and the tensile stress layer in the thickness direction of the tempered glass It is preferable to determine the presence or absence of chemical strengthening by checking the position.
  • chemical strengthening is performed by confirming that the center position in the thickness direction of the non-stress layer exists on the compressive stress layer side of the center position in the thickness direction of the tempered glass. It is preferable to determine that
  • the present invention further comprises a confirmation step of confirming the position of the stress-free layer inside the tempered glass before the chemical strengthening by cross Nicols observation with a polarizing microscope, and in the determination step, the inside of the tempered glass confirming that the center position in the thickness direction of the stress-free layer in is shifted to the compressive stress layer side from the center position in the thickness direction of the stress-free layer inside the tempering glass before the chemical strengthening. It is preferable to determine that chemical strengthening has been performed.
  • thermoform the glass by a redraw method in the forming step.
  • the tempered glass is a glass tube, and in the tempering step, the tempering glass is chemically tempered so that the compressive stress layer is formed on the outer surface of the glass tube.
  • a tempered glass manufacturing method capable of reliably and stably manufacturing tempered glass having a compressive stress layer.
  • FIG. 1 is a schematic cross-sectional view showing tempering glass before chemical strengthening in the case of manufacturing a glass tube as tempered glass.
  • FIG. 2 is a schematic cross-sectional view showing tempered glass after chemical strengthening in the case of manufacturing a glass tube as tempered glass.
  • FIG. 3 is a photograph showing the tempering glass before chemical strengthening obtained by crossed Nicols observation with a polarizing microscope.
  • FIG. 4 is a photograph showing tempered glass after chemical strengthening obtained by crossed Nicols observation with a polarizing microscope.
  • tempered glass is obtained by thermoforming glass (forming step).
  • the tempered glass obtained in the molding step is chemically tempered to obtain tempered glass having a compressive stress layer on its surface (strengthening step).
  • stress layer was formed on the surface of the tempered glass obtained in the tempering process, and the position of the stress-free layer inside the tempered glass was confirmed. , to discriminate the presence or absence of chemical strengthening (discrimination step).
  • the method for producing tempered glass of the present invention has the above configuration, so that tempered glass having a compressive stress layer can be produced reliably and stably. This point can be explained as follows.
  • the compressive stress layer in tempered glass can be confirmed by cross-Nicol observation using a polarizing microscope. In the crossed nicols observation with a polarizing microscope, it can be determined that the high-brightness portion in the obtained image is the compressive stress layer.
  • the tempered glass that has undergone the thermoforming process is chemically strengthened, in the crossed Nicols observation with a polarizing microscope, the tempered glass before chemical strengthening sometimes has a high brightness portion. In this case, it was difficult to distinguish the difference in brightness before and after chemical strengthening, and it was sometimes impossible to confirm the presence or absence of the formation of a compressive stress layer. Therefore, there is a problem that it is difficult to reliably and stably obtain tempered glass having a compressive stress layer.
  • the present inventors found that, when producing tempered glass by thermoforming by a method such as the redraw method, the stress remains inside due to quenching and air-cooling tempering is performed. It was found that a stress layer may be formed, and this is the cause of the observation of high brightness areas even in tempered glass before chemical strengthening. Therefore, even if a compressive stress layer is formed on the surface of this tempered glass by subsequent chemical strengthening, it is difficult to determine whether it is a compressive stress layer formed by thermoforming or a compressive stress layer formed by chemical strengthening. There was a problem that it was difficult to determine.
  • the inventor of the present invention confirms the position of the stress-free layer inside the obtained tempered glass, thereby confirming the chemical strengthening. It was found that the presence or absence can be determined.
  • the presence or absence of chemical strengthening can be determined as follows.
  • the following embodiment demonstrates the case where the glass for strengthening before chemical strengthening is obtained by the redraw method.
  • FIG. 1 is a schematic cross-sectional view showing tempering glass before chemical strengthening in the case of manufacturing a glass tube as tempered glass.
  • FIG. 1 is a schematic diagram of a cross section of the tempering glass 1 perpendicular to the tube length direction.
  • a compressive stress layer 2 is formed by quenching on the outer surface 1a of the tempering glass 1 that has been thermoformed by the redraw method before being chemically tempered.
  • a tensile stress layer 3 is formed on the inner surface 1b of the tempering glass 1 .
  • stress-free layers 4 are formed between the compressive stress layers 2 and the tensile stress layers 3 in the thickness direction T of the tempering glass 1 by canceling each other's stresses.
  • FIG. 2 is a schematic cross-sectional view showing tempered glass after chemical strengthening in the case of manufacturing a glass tube as tempered glass.
  • the tempered glass 10 shown in FIG. 2 is tempered glass obtained by chemically strengthening the outer surface 1a side of the tempering glass 1 shown in FIG.
  • FIG. 2 is a schematic diagram of a cross section of the tempered glass 10 perpendicular to the tube length direction.
  • the center position T2 in the thickness direction of the stress-free layer 4 exists in the tempered glass 10 obtained by chemically strengthening the outer surface 1a side of the tempering glass 1 shown in FIG. .
  • the position of the stress-free layer 4 can be confirmed by cross Nicols observation with a polarizing microscope.
  • FIG. 3 is a photograph showing the tempering glass before chemical strengthening obtained by cross-Nicol observation with a polarizing microscope.
  • FIG. 4 is a photograph showing tempered glass after chemical strengthening obtained by crossed Nicols observation with a polarizing microscope.
  • the high-brightness (bright) portion is the stress layer
  • the low-brightness (dark) portion sandwiched between the high-brightness stress layers is the non-stress layer 4 .
  • the compressive stress layer 2 is a bright (bright) portion of the outer surface 1a
  • the tensile stress layer 3 is a bright (bright) portion of the inner surface 1b.
  • the direction of the arrow is a diagonal position.
  • the thickness direction center position T2 of the stress-free layer 4 exists on the side of the compressive stress layer 2 that is closer to the outer surface 1a than the thickness direction center position T1 of the tempered glass 10. It can be seen that 3 and 4, the center position T2 in the thickness direction of the stress-free layer 4 in the tempered glass 10 after chemical strengthening is closer to the center position T0 in the thickness direction of the stress-free layer 4 in the tempered glass 1 before chemical strengthening. It can be seen that there is a shift toward the compressive stress layer 2 side, which is the outer surface 1a side.
  • the distance L2 from the thickness direction central position T2 of the non-stress layer 4 to the compressive stress layer 2 and the distance from the thickness direction central position T1 of the tempered glass 10 to the compressive stress layer 2
  • the ratio (L2/L1) to L1 is preferably 0.9 or less, more preferably 0.8 or less.
  • the thickness direction center position T2 of the stress-free layer 4 exists on the compressive stress layer 2 side from the thickness direction center position T1 of the tempered glass 10. Therefore, it can be determined that chemical strengthening has been performed.
  • the stress-free layer 4 in the tempered glass 10 Chemical strengthening is performed by confirming that the center position T2 in the thickness direction of is shifted to the side of the compressive stress layer 2 from the center position T0 in the thickness direction of the non-stress layer 4 in the tempering glass 1 before chemical strengthening. It can be determined that However, in the present invention, the step of confirming the position of the stress-free layer 4 inside the tempering glass 1 before chemical strengthening may be omitted.
  • crossed Nicols observation with a polarizing microscope can be performed by vertically illuminating the cross-section, which is the observation surface of the tempered glass 10, with polarized light through a polarizing microscope and observing with crossed Nicols.
  • a polarizing microscope for example, product number "BX53-P" manufactured by Olympus can be used.
  • the tempered glass 10 may be subjected to observation after etching or polishing the cross section, which is the observation surface of the tempered glass 10 .
  • the high-brightness (bright) part is the stress layer
  • the low-brightness (dark) part is the non-stress layer. Therefore, in cross Nicols observation with a polarizing microscope, the thickness of the stress layer can be obtained from the area where the high-brightness (bright) part is provided, and the thickness of the non-stress layer can be obtained from the area where the low-brightness (dark) part is provided. can be asked for.
  • the thickness of the compressive stress layer 2 in the tempering glass 1 can be, for example, 0.05 mm or more and 0.3 mm or less. Moreover, the thickness of the compressive stress layer 2 in the tempered glass 10 can be, for example, 0.01 mm or more and 0.25 mm or less.
  • the thickness of the non-stress layer 4 in the tempered glass 1 can be, for example, 0.3 mm or more and 0.6 mm or less. Moreover, the thickness of the non-stress layer 4 in the tempered glass 10 can be, for example, 0.1 mm or more and 0.4 mm or less.
  • the thickness of the tensile stress layer 3 in the tempering glass 1 can be, for example, 0.05 mm or more and 0.3 mm or less. Moreover, the thickness of the tensile stress layer 3 in the tempered glass 10 can be, for example, 0.1 mm or more and 0.4 mm or less.
  • the compressive stress value of the compressive stress layer 2 in the tempered glass 10 after chemical strengthening is preferably 3 MPa or more, more preferably 5 MPa or more.
  • the mechanical strength of the tempered glass 10 can be further enhanced.
  • the compressive stress value of the compressive stress layer 2 can be calculated, for example, by observing the number of interference fringes and their intervals using a surface stress meter.
  • borosilicate glass has an optical elastic constant of 34.0 [(nm/cm)/MPa]
  • aluminosilicate glass has an optical elastic constant of 29.0 [(nm/cm)/MPa]. (nm/cm)/MPa].
  • FSM-6000 manufactured by Toshiba Corporation can be used as a surface stress meter.
  • the tensile stress value of the tensile stress layer 3 in the tempered glass 10 after chemical strengthening can be, for example, 1 MPa or more and 3 MPa or less.
  • the tensile stress value of the tensile stress layer 3 can be derived, for example, by calculating the stress from the results of birefringence measurements.
  • the stress value of the non-stress layer 4 in the tempered glass 1 and tempered glass 10 is preferably 1 MPa or less, more preferably 0.5 MPa or less, even more preferably 0.2 MPa or less, and particularly preferably 0 MPa.
  • the tempered glass 10 is a glass tube.
  • the tempered glass 10 may be glass having another shape such as a glass plate, and the shape is not particularly limited. However, from the viewpoint of obtaining the effects of the present invention more reliably, it is preferable that the tempered glass 10 is a glass tube.
  • the thickness of the tempered glass 10 is not particularly limited, it is preferably 0.3 mm or more, more preferably 0.5 mm or more, preferably 10 mm or less, and more preferably 5 mm or less. When the thickness of the tempered glass 10 is within the above range, it is possible to further increase the mechanical strength while maintaining the production efficiency of the tempered glass 10 .
  • the inner diameter of the tempered glass 10 is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.8 mm or more, still more preferably 1 mm or more, preferably 10 mm or less, more preferably 5 mm or less, and still more preferably 3 mm. It is below.
  • thermoforming may be performed by blow molding, Danner molding, or the like, and is not particularly limited. Any method may be used as long as a stress layer or a non-stress layer is formed on the glass for strengthening 1 before chemical strengthening. However, from the viewpoint of obtaining the effects of the present invention more reliably, it is desirable to obtain the tempering glass 1 by thermoforming by a redraw method.
  • tempering glass for example, a glass having a known composition that enables chemical strengthening by ion exchange can be used.
  • the glass composition is SiO 2 50% to 80%, Al 2 O 3 1% to 20%, B 2 O 3 0% to 20%, and Na 2 O 1% in terms of mass %. 20%, K 2 O 0%-15%, Li 2 O 0%-10%.
  • SiO2 is a component that forms the network of glass.
  • the content of SiO2 is preferably 53% or more, more preferably 55% or more, still more preferably 60% or more, preferably 78% or less, more preferably 75% or less, even more preferably 72% or less.
  • the content of SiO 2 is equal to or higher than the above lower limit, vitrification is further facilitated, and acid resistance can be further enhanced.
  • the content of SiO 2 is equal to or less than the above upper limit, the meltability and formability can be further improved. Also, since the coefficient of thermal expansion does not become too low, it is possible to more easily match the coefficient of thermal expansion of the surrounding materials.
  • Al 2 O 3 is a component that increases the ion exchange rate, and also a component that increases the Young's modulus and hardness.
  • the content of Al 2 O 3 is preferably 3% or more, more preferably 4% or more, still more preferably 5% or more, preferably 18% or less, more preferably 15% or less, further preferably 12% or less. is.
  • the content of Al 2 O 3 is at least the above lower limit, the ion exchange rate and Young's modulus can be further improved, the acid resistance can be further improved, and the acid treatment process can be applied more easily. can do.
  • the content of Al 2 O 3 is equal to or less than the above upper limit, the high-temperature viscosity can be lowered, and the meltability can be further improved.
  • B 2 O 3 is a component that lowers high-temperature viscosity and density and increases devitrification resistance.
  • the content of B 2 O 3 is not particularly limited, but is preferably 18% or less, more preferably 16% or less, still more preferably 14% or less, and particularly preferably 12% or less.
  • the ion exchange rate can be further increased.
  • coloration of the glass surface due to ion exchange can be further suppressed, and acid resistance and water resistance can be further improved.
  • Na 2 O is an ion-exchange component and also a component that lowers high-temperature viscosity and enhances meltability and moldability. Na 2 O is also a component that enhances devitrification resistance.
  • the content of Na 2 O is not particularly limited, and is preferably 2% or more, more preferably 3% or more, still more preferably 5% or more, preferably 18% or less, more preferably 15% or less, and even more preferably. is 12% or less.
  • the meltability and thermal expansion coefficient can be further increased, and the ion exchange rate can be further increased.
  • acid resistance and devitrification resistance can be further improved.
  • K 2 O is a component that lowers high-temperature viscosity and improves meltability and moldability. It is also a component that increases devitrification resistance and Vickers hardness.
  • the content of K 2 O is not particularly limited, and is preferably 0.1% or more, more preferably 1% or more, still more preferably 2% or more, preferably 10% or less, more preferably 5% or less, More preferably less than 3%. When the K 2 O content is within the above range, the acid resistance and devitrification resistance can be further improved.
  • Li 2 O is an ion-exchange component that lowers high-temperature viscosity and improves meltability and moldability. It is also a component that increases Young's modulus. Furthermore, Li 2 O is also a component that elutes out during the ion exchange treatment and deteriorates the ion exchange solution. Therefore, the content of Li 2 O is preferably 0.01% or more, preferably 2% or less, more preferably 1% or less, and still more preferably 0.1% or less.
  • the following components can be included in the glass as components other than the above.
  • MgO is a component that lowers high-temperature viscosity and improves meltability and moldability. It is also a component that increases Young's modulus to increase Vickers hardness and acid resistance.
  • the content of MgO is preferably 0.1% or more, more preferably 1% or more, still more preferably 2% or more, preferably 4.5% or less, more preferably 3% or less, further preferably 2.0% or more. 5% or less. When the content of MgO is within the above range, the ion exchange rate can be further increased, and the devitrification of the glass can be made more difficult.
  • P 2 O 5 is a component that increases the ion exchange rate while maintaining the compressive stress value.
  • the content of P 2 O 5 is preferably 2% or more, more preferably 3.5% or more, still more preferably 4.5% or more, preferably 8% or less, more preferably 6% or less, still more preferably is 5% or less.
  • water resistance can be further improved.
  • Cl, SO 3 or CeO 2 may be added as a refining agent to the glass constituting the tempered glass, and Cl or SO 3 is preferably added.
  • the content of the clarifier can be, for example, 0% or more and 3% or less.
  • the glass constituting the tempering glass may contain SnO 2 .
  • SnO2 has the effect of enhancing the ion exchange performance.
  • the SnO 2 content is preferably 0.01% or more, more preferably 0.05% or more, still more preferably 0.1% or more, and preferably 3% or less.
  • the content of Fe 2 O 3 in the glass constituting the tempering glass is preferably less than 1000 ppm (less than 0.1%), more preferably less than 400 ppm, still more preferably less than 300 ppm.
  • the transmittance (400 nm to 770 nm) at a plate thickness of 1 mm can be further improved.
  • the content of rare earth oxides such as Nb 2 O 5 and La 2 O 3 in the glass constituting the tempered glass is preferably 3% or less, more preferably 1% or less, and still more preferably 0.1% or less. be. In this case, devitrification resistance can be further improved.
  • the glass constituting the tempering glass does not substantially contain As 2 O 3 , Sb 2 O 3 and PbO in terms of the glass composition.
  • substantially no Bi 2 O 3 or F is contained from environmental considerations.
  • the glass to be tempered can be obtained by heat-melting the glass prepared so as to have the glass composition described above and thermoforming the melt by a redraw method or the like.
  • the heating and melting of the frit can be performed, for example, by putting the frit into a continuous melting furnace and heating it at 1500°C to 1600°C. It can be carried out.
  • the tempered glass can be produced by chemically tempering the tempered glass thus obtained.
  • the chemical strengthening method is a method of introducing alkali ions having a large ionic radius to the surface of the glass for strengthening by ion exchange treatment at a temperature below the strain point of the glass. With the chemical strengthening method, a compressive stress layer can be formed satisfactorily even if the thickness of the glass to be strengthened is thin, so that desired mechanical strength can be obtained.
  • the conditions for the ion exchange treatment are not particularly limited, and may be determined in consideration of the viscosity characteristics of the tempering glass.
  • the ion exchange treatment can be performed by immersing the tempering glass in a potassium nitrate solution at 400° C. to 550° C. for 1 hour to 8 hours.
  • composition of the tempered glass obtained by subjecting the tempering glass to ion exchange treatment can be the same as the composition of the tempering glass before the ion exchange treatment.

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Abstract

rovided is a production method for strengthened glass whereby strengthened glass having a compressive stress layer can be produced reliably and stably.　This production method for strengthened glass 10 comprises: a molding step for obtaining, by thermoforming glass, a glass to be strengthened; a strengthening step for obtaining strengthened glass 10 having a compressive stress layer 2 on a surface 1a by chemically strengthening the glass to be strengthened; and a determination step for determining whether chemical strengthening has taken place by confirming, by crossed-Nicol observation using a polarizing microscope, that stress layers 2, 3 have been formed on the surfaces 1a, 1b of the strengthened glass 10, and confirming the position of a non-stress layer 4 on the interior of the strengthened glass 10.

Description

強化ガラスの製造方法tempered glass manufacturing method
　本発明は、圧縮応力層を有する、強化ガラスの製造方法に関する。 The present invention relates to a method for manufacturing tempered glass having a compressive stress layer.
　従来、スマートフォン用カバーガラスや、自動車のフロントガラスなどのガラス製品には、割れ防止や機械的強度の向上などを目的として、表面が強化された強化ガラスが用いられることがある。このような強化ガラスでは、化学強化処理などの方法により、ガラスの表面に圧縮応力層を形成することによって、キズの発生やクラックの伸展が抑制されている。 Conventionally, glass products such as cover glass for smartphones and windshields of automobiles sometimes use tempered glass with a reinforced surface for the purpose of preventing cracking and improving mechanical strength. In such tempered glass, a compressive stress layer is formed on the surface of the glass by a method such as chemical strengthening treatment, thereby suppressing the occurrence of scratches and the extension of cracks.
　強化ガラスにおける圧縮応力層の形成は、偏光顕微鏡によるクロスニコル観察によって確認できることが知られている。例えば、下記の特許文献１では、偏光顕微鏡によるクロスニコル観察において、明度の高い部分を圧縮応力層であると識別して、その厚みを測定することにより、圧縮応力層の深さを測定できることが記載されている。 It is known that the formation of a compressive stress layer in tempered glass can be confirmed by cross-Nicol observation using a polarizing microscope. For example, in Patent Document 1 below, in cross Nicols observation with a polarizing microscope, a portion with high brightness is identified as a compressive stress layer, and the thickness thereof is measured to measure the depth of the compressive stress layer. Are listed.
特開２０１２－２２９１５４号公報JP 2012-229154 A
　ところで、リドロー法などの方法によって熱成形されたガラスを化学強化することにより得られた強化ガラスでは、偏光顕微鏡によるクロスニコル観察において、化学強化前にも明度の高い部分が観察されることがあるが、化学強化の前後でその明度の違いを区別することが難しく、圧縮応力層形成の有無を確認できない場合がある。そのため、圧縮応力層を有する強化ガラスを確実にかつ安定して製造することが難しいという問題がある。 By the way, in tempered glass obtained by chemically strengthening thermoformed glass by a method such as the redraw method, in cross Nicols observation with a polarizing microscope, a part with high brightness may be observed even before chemical strengthening. However, it is difficult to distinguish the difference in brightness before and after chemical strengthening, and it may not be possible to confirm the presence or absence of compressive stress layer formation. Therefore, there is a problem that it is difficult to reliably and stably produce tempered glass having a compressive stress layer.
　本発明の目的は、圧縮応力層を有する強化ガラスを確実にかつ安定して製造することができる、強化ガラスの製造方法を提供することにある。 An object of the present invention is to provide a method for producing tempered glass that can reliably and stably produce tempered glass having a compressive stress layer.
　本発明に係る強化ガラスの製造方法は、ガラスを熱成形することにより、強化用ガラスを得る、成形工程と、前記強化用ガラスを化学強化することにより、表面に圧縮応力層を有する強化ガラスを得る、強化工程と、偏光顕微鏡によるクロスニコル観察によって、前記強化ガラスの表面に応力層が形成されていることを確認するとともに、前記強化ガラスの内部における無応力層の位置を確認することにより、化学強化の有無を判別する、判別工程とを備えることを特徴としている。 The method for producing tempered glass according to the present invention includes a forming step of obtaining tempered glass by thermoforming glass, and chemically tempering the tempered glass to obtain tempered glass having a compressive stress layer on the surface. By confirming that a stress layer is formed on the surface of the tempered glass by the strengthening step and cross-Nicol observation with a polarizing microscope, and by confirming the position of the stress-free layer inside the tempered glass, It is characterized by comprising a discrimination step of discriminating the presence or absence of chemical strengthening.
　本発明においては、前記強化ガラスが、対向している第１の主面及び第２の主面を有し、前記判別工程において、前記強化ガラスの前記第１の主面に圧縮応力層が形成され、かつ前記第２の主面に引張応力層が形成されていることを確認するとともに、前記強化ガラスの厚み方向において前記圧縮応力層及び前記引張応力層の間に存在する前記無応力層の位置を確認することにより、化学強化の有無を判別することが好ましい。 In the present invention, the tempered glass has a first main surface and a second main surface facing each other, and in the determining step, a compressive stress layer is formed on the first main surface of the tempered glass. and confirming that a tensile stress layer is formed on the second main surface, and the non-stress layer existing between the compressive stress layer and the tensile stress layer in the thickness direction of the tempered glass It is preferable to determine the presence or absence of chemical strengthening by checking the position.
　本発明においては、前記判別工程において、前記強化ガラスの厚み方向中心位置よりも前記圧縮応力層側に、前記無応力層の厚み方向中心位置が存在することを確認することにより、化学強化がなされていると判別することが好ましい。 In the present invention, in the determination step, chemical strengthening is performed by confirming that the center position in the thickness direction of the non-stress layer exists on the compressive stress layer side of the center position in the thickness direction of the tempered glass. It is preferable to determine that
　本発明においては、偏光顕微鏡によるクロスニコル観察により、前記化学強化前の前記強化用ガラスの内部における無応力層の位置を確認する、確認工程をさらに備え、前記判別工程において、前記強化ガラスの内部における前記無応力層の厚み方向中心位置が、前記化学強化前の前記強化用ガラスの内部における前記無応力層の厚み方向中心位置よりも前記圧縮応力層側にシフトしていることを確認することにより、化学強化がなされていると判別することが好ましい。 The present invention further comprises a confirmation step of confirming the position of the stress-free layer inside the tempered glass before the chemical strengthening by cross Nicols observation with a polarizing microscope, and in the determination step, the inside of the tempered glass confirming that the center position in the thickness direction of the stress-free layer in is shifted to the compressive stress layer side from the center position in the thickness direction of the stress-free layer inside the tempering glass before the chemical strengthening. It is preferable to determine that chemical strengthening has been performed.
　本発明においては、前記成形工程において、リドロー法により前記ガラスを熱成形することが好ましい。 In the present invention, it is preferable to thermoform the glass by a redraw method in the forming step.
　本発明においては、前記強化ガラスが、ガラス管であり、前記強化工程において、前記ガラス管の外表面に前記圧縮応力層が形成されるように、前記強化用ガラスを化学強化することが好ましい。 In the present invention, it is preferable that the tempered glass is a glass tube, and in the tempering step, the tempering glass is chemically tempered so that the compressive stress layer is formed on the outer surface of the glass tube.
　本発明によれば、圧縮応力層を有する強化ガラスを確実にかつ安定して製造することができる、強化ガラスの製造方法を提供することができる。 According to the present invention, it is possible to provide a tempered glass manufacturing method capable of reliably and stably manufacturing tempered glass having a compressive stress layer.
図１は、強化ガラスとしてガラス管を製造する場合において、化学強化前の強化用ガラスを示す模式的断面図である。FIG. 1 is a schematic cross-sectional view showing tempering glass before chemical strengthening in the case of manufacturing a glass tube as tempered glass. 図２は、強化ガラスとしてガラス管を製造する場合において、化学強化後の強化ガラスを示す模式的断面図である。FIG. 2 is a schematic cross-sectional view showing tempered glass after chemical strengthening in the case of manufacturing a glass tube as tempered glass. 図３は、偏光顕微鏡によるクロスニコル観察により得られた化学強化前の強化用ガラスを示す写真である。FIG. 3 is a photograph showing the tempering glass before chemical strengthening obtained by crossed Nicols observation with a polarizing microscope. 図４は、偏光顕微鏡によるクロスニコル観察により得られた化学強化後の強化ガラスを示す写真である。FIG. 4 is a photograph showing tempered glass after chemical strengthening obtained by crossed Nicols observation with a polarizing microscope.
　以下、好ましい実施形態について説明する。但し、以下の実施形態は単なる例示であり、本発明は以下の実施形態に限定されるものではない。また、各図面において、実質的に同一の機能を有する部材は同一の符号で参照する場合がある。 A preferred embodiment will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Also, in each drawing, members having substantially the same function may be referred to by the same reference numerals.
　本発明の強化ガラスの製造方法では、まず、ガラスを熱成形することにより、強化用ガラスを得る（成形工程）。次に、成形工程で得られた強化用ガラスを化学強化することにより、表面に圧縮応力層を有する強化ガラスを得る（強化工程）。次に、偏光顕微鏡によるクロスニコル観察によって、強化工程で得られた強化ガラスの表面に応力層が形成されていることを確認するとともに、強化ガラスの内部における無応力層の位置を確認することにより、化学強化の有無を判別する（判別工程）。これらの工程を経て、本発明の強化ガラスを得ることができる。 In the method for producing tempered glass of the present invention, first, tempered glass is obtained by thermoforming glass (forming step). Next, the tempered glass obtained in the molding step is chemically tempered to obtain tempered glass having a compressive stress layer on its surface (strengthening step). Next, by cross Nicols observation with a polarizing microscope, it was confirmed that a stress layer was formed on the surface of the tempered glass obtained in the tempering process, and the position of the stress-free layer inside the tempered glass was confirmed. , to discriminate the presence or absence of chemical strengthening (discrimination step). Through these steps, the tempered glass of the present invention can be obtained.
　本発明の強化ガラスの製造方法は、上記の構成を備えるので、圧縮応力層を有する強化ガラスを確実にかつ安定して製造することができる。なお、この点については、以下のようにして説明することができる。 The method for producing tempered glass of the present invention has the above configuration, so that tempered glass having a compressive stress layer can be produced reliably and stably. This point can be explained as follows.
　従来、強化ガラスにおける圧縮応力層は、偏光顕微鏡によるクロスニコル観察によって確認できることが知られている。偏光顕微鏡によるクロスニコル観察においては、得られる像において、明度の高い部分を圧縮応力層であると判別することができる。 Conventionally, it is known that the compressive stress layer in tempered glass can be confirmed by cross-Nicol observation using a polarizing microscope. In the crossed nicols observation with a polarizing microscope, it can be determined that the high-brightness portion in the obtained image is the compressive stress layer.
　ところが、熱成形工程を経た強化用ガラスを化学強化する場合、偏光顕微鏡によるクロスニコル観察において、化学強化前の強化用ガラスにも明度の高い部分が観察されることがあった。この場合、化学強化の前後でその明度の違いを区別することが難しく、圧縮応力層形成の有無を確認することができない場合があった。そのため、圧縮応力層を有する強化ガラスを確実にかつ安定して得ることが難しいという問題があった。 However, when the tempered glass that has undergone the thermoforming process is chemically strengthened, in the crossed Nicols observation with a polarizing microscope, the tempered glass before chemical strengthening sometimes has a high brightness portion. In this case, it was difficult to distinguish the difference in brightness before and after chemical strengthening, and it was sometimes impossible to confirm the presence or absence of the formation of a compressive stress layer. Therefore, there is a problem that it is difficult to reliably and stably obtain tempered glass having a compressive stress layer.
　本発明者は、この原因について鋭意検討した結果、リドロー法などの方法によって、熱成形することにより強化用ガラスを製造する場合、急冷によって内部に応力が残存して風冷強化した場合のように応力層が形成されることがあり、これが化学強化前の強化用ガラスにも明度の高い部分が観察される原因となることを見出した。そのため、その後の化学強化によりこの強化用ガラスの表面に圧縮応力層を形成しても、熱成形により形成された圧縮応力層であるか、あるいは化学強化により形成された圧縮応力層であるかを判別することが難しいという問題があった。 As a result of intensive investigation into the cause, the present inventors found that, when producing tempered glass by thermoforming by a method such as the redraw method, the stress remains inside due to quenching and air-cooling tempering is performed. It was found that a stress layer may be formed, and this is the cause of the observation of high brightness areas even in tempered glass before chemical strengthening. Therefore, even if a compressive stress layer is formed on the surface of this tempered glass by subsequent chemical strengthening, it is difficult to determine whether it is a compressive stress layer formed by thermoforming or a compressive stress layer formed by chemical strengthening. There was a problem that it was difficult to determine.
　これに対して、本発明者は、上記のような熱成形により得られた強化用ガラスを化学強化する場合、得られる強化ガラスの内部における無応力層の位置を確認することにより、化学強化の有無を判別できることを見出した。 On the other hand, when the glass for strengthening obtained by thermoforming as described above is chemically strengthened, the inventor of the present invention confirms the position of the stress-free layer inside the obtained tempered glass, thereby confirming the chemical strengthening. It was found that the presence or absence can be determined.
　例えば、強化ガラスとしてガラス管を製造する場合は、以下のようして化学強化の有無を判別することができる。なお、以下の実施形態では、リドロー法により化学強化前の強化用ガラスを得る場合について説明する。 For example, when manufacturing a glass tube as tempered glass, the presence or absence of chemical strengthening can be determined as follows. In addition, the following embodiment demonstrates the case where the glass for strengthening before chemical strengthening is obtained by the redraw method.
　（ガラス管の製造方法）
　図１は、強化ガラスとしてガラス管を製造する場合において、化学強化前の強化用ガラスを示す模式的断面図である。なお、図１は、強化用ガラス１の管長方向に直交する断面の模式図である。 (Method for manufacturing glass tube)
FIG. 1 is a schematic cross-sectional view showing tempering glass before chemical strengthening in the case of manufacturing a glass tube as tempered glass. In addition, FIG. 1 is a schematic diagram of a cross section of the tempering glass 1 perpendicular to the tube length direction.
　強化ガラスとしてガラス管を製造する場合、リドロー法により熱成形された化学強化前の強化用ガラス１の外表面１ａには、急冷によって圧縮応力層２が形成される。一方で、強化用ガラス１の内表面１ｂには、引張応力層３が形成される。また、強化用ガラス１の厚み方向Ｔにおいて、圧縮応力層２及び引張応力層３の間には、それぞれの応力が相殺されて無応力層４が形成される。 When manufacturing a glass tube as tempered glass, a compressive stress layer 2 is formed by quenching on the outer surface 1a of the tempering glass 1 that has been thermoformed by the redraw method before being chemically tempered. On the other hand, a tensile stress layer 3 is formed on the inner surface 1b of the tempering glass 1 . In addition, stress-free layers 4 are formed between the compressive stress layers 2 and the tensile stress layers 3 in the thickness direction T of the tempering glass 1 by canceling each other's stresses.
　図２は、強化ガラスとしてガラス管を製造する場合において、化学強化後の強化ガラスを示す模式的断面図である。なお、図２に示す強化ガラス１０は、図１に示す強化用ガラス１の外表面１ａ側を化学強化することにより得られた強化ガラスである。また、図２は、強化ガラス１０の管長方向に直交する断面の模式図である。 FIG. 2 is a schematic cross-sectional view showing tempered glass after chemical strengthening in the case of manufacturing a glass tube as tempered glass. The tempered glass 10 shown in FIG. 2 is tempered glass obtained by chemically strengthening the outer surface 1a side of the tempering glass 1 shown in FIG. Moreover, FIG. 2 is a schematic diagram of a cross section of the tempered glass 10 perpendicular to the tube length direction.
　図２に示すように、図１に示す強化用ガラス１の外表面１ａ側を化学強化することにより得られた強化ガラス１０では、強化ガラス１０の厚み方向中心位置Ｔ１よりも圧縮応力層２側に、無応力層４の厚み方向中心位置Ｔ２が存在していることがわかる。なお、無応力層４の位置については、偏光顕微鏡によるクロスニコル観察により確認することができる。 As shown in FIG. 2, in the tempered glass 10 obtained by chemically strengthening the outer surface 1a side of the tempering glass 1 shown in FIG. , the center position T2 in the thickness direction of the stress-free layer 4 exists. The position of the stress-free layer 4 can be confirmed by cross Nicols observation with a polarizing microscope.
　図３は、偏光顕微鏡によるクロスニコル観察により得られた化学強化前の強化用ガラスを示す写真である。また、図４は、偏光顕微鏡によるクロスニコル観察により得られた化学強化後の強化ガラスを示す写真である。図３及び図４の対角位において、明度の高い（明るい）部分が応力層であり、明度の高い応力層間に挟まれる明度の低い（暗い）部分が無応力層４である。また、外表面１ａにおける明度の高い（明るい）部分が圧縮応力層２であり、内表面１ｂにおける明度の高い（明るい）部分が引張応力層３である。なお、図３及び図４においては、矢印の方向が対角位である。 Fig. 3 is a photograph showing the tempering glass before chemical strengthening obtained by cross-Nicol observation with a polarizing microscope. Moreover, FIG. 4 is a photograph showing tempered glass after chemical strengthening obtained by crossed Nicols observation with a polarizing microscope. 3 and 4, the high-brightness (bright) portion is the stress layer, and the low-brightness (dark) portion sandwiched between the high-brightness stress layers is the non-stress layer 4 . The compressive stress layer 2 is a bright (bright) portion of the outer surface 1a, and the tensile stress layer 3 is a bright (bright) portion of the inner surface 1b. In addition, in FIG.3 and FIG.4, the direction of the arrow is a diagonal position.
　図４より、化学強化後の強化ガラス１０では、強化ガラス１０の厚み方向中心位置Ｔ１よりも外表面１ａ側である圧縮応力層２側に、無応力層４の厚み方向中心位置Ｔ２が存在していることがわかる。また、図３及び図４より、化学強化後の強化ガラス１０における無応力層４の厚み方向中心位置Ｔ２が、化学強化前の強化用ガラス１における無応力層４の厚み方向中心位置Ｔ０よりも外表面１ａ側である圧縮応力層２側にシフトしていることがわかる。 4, in the tempered glass 10 after chemical strengthening, the thickness direction center position T2 of the stress-free layer 4 exists on the side of the compressive stress layer 2 that is closer to the outer surface 1a than the thickness direction center position T1 of the tempered glass 10. It can be seen that 3 and 4, the center position T2 in the thickness direction of the stress-free layer 4 in the tempered glass 10 after chemical strengthening is closer to the center position T0 in the thickness direction of the stress-free layer 4 in the tempered glass 1 before chemical strengthening. It can be seen that there is a shift toward the compressive stress layer 2 side, which is the outer surface 1a side.
　このように、熱成形による応力と化学強化による応力が組み合わされた場合、無応力層４の位置が、化学強化された圧縮応力層２側にシフトする。化学強化では、極表層に強い圧縮応力を付与するため、これに反発する引張応力がより広い領域を占めることになる。その結果として、圧縮応力層２及び引張応力層３に挟まれる無応力層４が圧縮応力層２側にシフトするものと考えられる。従って、この現象を確認することにより、化学強化の有無を判別することができる。 Thus, when the stress due to thermoforming and the stress due to chemical strengthening are combined, the position of the stress-free layer 4 shifts to the chemically strengthened compressive stress layer 2 side. In chemical strengthening, since strong compressive stress is applied to the extreme surface layer, tensile stress repulsive to this occupies a wider region. As a result, it is considered that the stress-free layer 4 sandwiched between the compressive stress layer 2 and the tensile stress layer 3 shifts toward the compressive stress layer 2 side. Therefore, by confirming this phenomenon, the presence or absence of chemical strengthening can be determined.
　なお、本発明においては、厚み方向Ｔにおいて、無応力層４の厚み方向中心位置Ｔ２から圧縮応力層２までの距離Ｌ２と、強化ガラス１０の厚み方向中心位置Ｔ１から圧縮応力層２までの距離Ｌ１との比（Ｌ２／Ｌ１）が、好ましくは０．９以下、より好ましくは０．８以下である。 In the present invention, in the thickness direction T, the distance L2 from the thickness direction central position T2 of the non-stress layer 4 to the compressive stress layer 2, and the distance from the thickness direction central position T1 of the tempered glass 10 to the compressive stress layer 2 The ratio (L2/L1) to L1 is preferably 0.9 or less, more preferably 0.8 or less.
　以上のように、化学強化後の判別工程においては、強化ガラス１０の厚み方向中心位置Ｔ１よりも圧縮応力層２側に、無応力層４の厚み方向中心位置Ｔ２が存在することを確認することにより、化学強化がなされていると判別することができる。 As described above, in the discrimination step after chemical strengthening, it is confirmed that the thickness direction center position T2 of the stress-free layer 4 exists on the compressive stress layer 2 side from the thickness direction center position T1 of the tempered glass 10. Therefore, it can be determined that chemical strengthening has been performed.
　また、化学強化前の強化用ガラス１の内部における無応力層４の位置を確認する工程（確認工程）をさらに設けた上で、化学強化後の判別工程において、強化ガラス１０における無応力層４の厚み方向中心位置Ｔ２が、化学強化前の強化用ガラス１における無応力層４の厚み方向中心位置Ｔ０よりも圧縮応力層２側にシフトしていることを確認することにより、化学強化がなされていると判別してもよい。もっとも、本発明において、化学強化前の強化用ガラス１の内部における無応力層４の位置を確認する工程は、省略してもよい。 In addition, after further providing a step (confirmation step) for checking the position of the stress-free layer 4 inside the tempering glass 1 before chemical strengthening, in the discrimination step after chemical strengthening, the stress-free layer 4 in the tempered glass 10 Chemical strengthening is performed by confirming that the center position T2 in the thickness direction of is shifted to the side of the compressive stress layer 2 from the center position T0 in the thickness direction of the non-stress layer 4 in the tempering glass 1 before chemical strengthening. It can be determined that However, in the present invention, the step of confirming the position of the stress-free layer 4 inside the tempering glass 1 before chemical strengthening may be omitted.
　本発明において、偏光顕微鏡によるクロスニコル観察は、強化ガラス１０の観察面である断面に偏光顕微鏡により垂直に偏光を入射し、直交ニコルで観察することにより行なうことができる。偏光顕微鏡としては、例えば、オリンパス社製、品番「ＢＸ５３－Ｐ」を用いることができる。 In the present invention, crossed Nicols observation with a polarizing microscope can be performed by vertically illuminating the cross-section, which is the observation surface of the tempered glass 10, with polarized light through a polarizing microscope and observing with crossed Nicols. As a polarizing microscope, for example, product number "BX53-P" manufactured by Olympus can be used.
　なお、偏光顕微鏡によるクロスニコル観察においては、強化ガラス１０の観察面である断面をエッチングしたり、研磨したりした後に、強化ガラス１０を観察に供してもよい。 In addition, in the cross-Nicols observation using a polarizing microscope, the tempered glass 10 may be subjected to observation after etching or polishing the cross section, which is the observation surface of the tempered glass 10 .
　また、偏光顕微鏡によるクロスニコル観察においては、明度の高い（明るい）部分が応力層となり、明度の低い（暗い）部分が無応力層となる。従って、偏光顕微鏡によるクロスニコル観察においては、明度の高い（明るい）部分の設けられる領域から応力層の厚みを求めることができ、明度の低い（暗い）部分の設けられる領域から無応力層の厚みを求めることができる。 In addition, in cross-Nicol observation with a polarizing microscope, the high-brightness (bright) part is the stress layer, and the low-brightness (dark) part is the non-stress layer. Therefore, in cross Nicols observation with a polarizing microscope, the thickness of the stress layer can be obtained from the area where the high-brightness (bright) part is provided, and the thickness of the non-stress layer can be obtained from the area where the low-brightness (dark) part is provided. can be asked for.
　また、偏光顕微鏡によるクロスニコル観察においては、化学強化前の強化用ガラス１や、化学強化後の強化ガラス１０について、いずれも全数の観察を行う必要はなく、一定数の中からの抜き取りによるものでも構わない。 In addition, in cross Nicol observation with a polarizing microscope, it is not necessary to observe all of the tempered glass 1 before chemical strengthening and the tempered glass 10 after chemical strengthening, but by sampling from a certain number. But I don't mind.
　強化用ガラス１における圧縮応力層２の厚みは、例えば、０．０５ｍｍ以上、０．３ｍｍ以下とすることができる。また、強化ガラス１０における圧縮応力層２の厚みは、例えば、０．０１ｍｍ以上、０．２５ｍｍ以下とすることができる。 The thickness of the compressive stress layer 2 in the tempering glass 1 can be, for example, 0.05 mm or more and 0.3 mm or less. Moreover, the thickness of the compressive stress layer 2 in the tempered glass 10 can be, for example, 0.01 mm or more and 0.25 mm or less.
　強化用ガラス１における無応力層４の厚みは、例えば、０．３ｍｍ以上、０．６ｍｍ以下とすることができる。また、強化ガラス１０における無応力層４の厚みは、例えば、０．１ｍｍ以上、０．４ｍｍ以下とすることができる。 The thickness of the non-stress layer 4 in the tempered glass 1 can be, for example, 0.3 mm or more and 0.6 mm or less. Moreover, the thickness of the non-stress layer 4 in the tempered glass 10 can be, for example, 0.1 mm or more and 0.4 mm or less.
　強化用ガラス１における引張応力層３の厚みは、例えば、０．０５ｍｍ以上、０．３ｍｍ以下とすることができる。また、強化ガラス１０における引張応力層３の厚みは、例えば、０．１ｍｍ以上、０．４ｍｍ以下とすることができる。 The thickness of the tensile stress layer 3 in the tempering glass 1 can be, for example, 0.05 mm or more and 0.3 mm or less. Moreover, the thickness of the tensile stress layer 3 in the tempered glass 10 can be, for example, 0.1 mm or more and 0.4 mm or less.
　本発明において、化学強化後の強化ガラス１０における圧縮応力層２の圧縮応力値は、好ましくは３ＭＰａ以上、より好ましくは５ＭＰａ以上である。圧縮応力層２の圧縮応力値が上記の場合、強化ガラス１０の機械的強度をより一層高めることができる。 In the present invention, the compressive stress value of the compressive stress layer 2 in the tempered glass 10 after chemical strengthening is preferably 3 MPa or more, more preferably 5 MPa or more. When the compressive stress value of the compressive stress layer 2 is above, the mechanical strength of the tempered glass 10 can be further enhanced.
　圧縮応力層２の圧縮応力値は、例えば、表面応力計を用いて干渉縞の本数とその間隔を観察することにより算出することができる。算出に際しては、例えば、ホウケイ酸ガラスであれば、光学弾性定数を３４．０［（ｎｍ／ｃｍ）／ＭＰａ］とすることができ、アルミノシリケートガラスであれば、光学弾性定数を２９．０［（ｎｍ／ｃｍ）／ＭＰａ］とすることができる。また、表面応力計としては、株式会社東芝製、ＦＳＭ－６０００を用いることができる。 The compressive stress value of the compressive stress layer 2 can be calculated, for example, by observing the number of interference fringes and their intervals using a surface stress meter. For the calculation, for example, borosilicate glass has an optical elastic constant of 34.0 [(nm/cm)/MPa], and aluminosilicate glass has an optical elastic constant of 29.0 [(nm/cm)/MPa]. (nm/cm)/MPa]. As a surface stress meter, FSM-6000 manufactured by Toshiba Corporation can be used.
　化学強化後の強化ガラス１０における引張応力層３の引張応力値は、例えば、１ＭＰａ以上、３ＭＰａ以下とすることができる。引張応力層３の引張応力値は、例えば、複屈折測定の結果から応力を計算することによって導くことができる。 The tensile stress value of the tensile stress layer 3 in the tempered glass 10 after chemical strengthening can be, for example, 1 MPa or more and 3 MPa or less. The tensile stress value of the tensile stress layer 3 can be derived, for example, by calculating the stress from the results of birefringence measurements.
　また、強化用ガラス１及び強化ガラス１０における無応力層４の応力値は、好ましくは１ＭＰａ以下、より好ましくは０．５ＭＰａ以下、さらに好ましくは０．２ＭＰａ以下、特に好ましくは０ＭＰａである。 In addition, the stress value of the non-stress layer 4 in the tempered glass 1 and tempered glass 10 is preferably 1 MPa or less, more preferably 0.5 MPa or less, even more preferably 0.2 MPa or less, and particularly preferably 0 MPa.
　なお、上記実施形態では、強化ガラス１０がガラス管である場合について説明した。もっとも、本発明において、強化ガラス１０は、ガラス板などの他の形状を有するガラスであってもよく、その形状は特に限定されない。もっとも、本発明の効果をより一層確実に得る観点からは、強化ガラス１０がガラス管であることが好ましい。 In addition, in the above embodiment, the case where the tempered glass 10 is a glass tube has been described. However, in the present invention, the tempered glass 10 may be glass having another shape such as a glass plate, and the shape is not particularly limited. However, from the viewpoint of obtaining the effects of the present invention more reliably, it is preferable that the tempered glass 10 is a glass tube.
　また、強化ガラス１０の厚みは、特に限定されないが、好ましくは０．３ｍｍ以上、より好ましくは０．５ｍｍ以上、好ましくは１０ｍｍ以下、より好ましくは５ｍｍ以下である。強化ガラス１０の厚みが上記範囲内にある場合、強化ガラス１０の生産効率を維持しつつ、機械的強度をより一層高めることができる。 Although the thickness of the tempered glass 10 is not particularly limited, it is preferably 0.3 mm or more, more preferably 0.5 mm or more, preferably 10 mm or less, and more preferably 5 mm or less. When the thickness of the tempered glass 10 is within the above range, it is possible to further increase the mechanical strength while maintaining the production efficiency of the tempered glass 10 .
　また、強化ガラス１０の内径は、特に限定されないが、好ましくは０．１ｍｍ以上、より好ましくは０．８ｍｍ以上、さらに好ましくは１ｍｍ以上、好ましくは１０ｍｍ以下、より好ましくは５ｍｍ以下、さらに好ましくは３ｍｍ以下である。 The inner diameter of the tempered glass 10 is not particularly limited, but is preferably 0.1 mm or more, more preferably 0.8 mm or more, still more preferably 1 mm or more, preferably 10 mm or less, more preferably 5 mm or less, and still more preferably 3 mm. It is below.
　また、上記実施形態では、リドロー法により熱成形して強化用ガラス１を得る方法について説明した。もっとも、本発明において、熱成形は、ブロー成形、ダンナー成形等により行ってもよく、特に限定はされない。化学強化前の強化用ガラス１に応力層や無応力層が形成される方法であればよい。もっとも、本発明の効果をより一層確実に得る観点からは、リドロー法により熱成形して強化用ガラス１を得ることが望ましい。 Further, in the above embodiment, the method of obtaining the tempering glass 1 by thermoforming by the redraw method has been described. However, in the present invention, thermoforming may be performed by blow molding, Danner molding, or the like, and is not particularly limited. Any method may be used as long as a stress layer or a non-stress layer is formed on the glass for strengthening 1 before chemical strengthening. However, from the viewpoint of obtaining the effects of the present invention more reliably, it is desirable to obtain the tempering glass 1 by thermoforming by a redraw method.
　以下、強化用ガラス及び強化ガラスの詳細について説明する。 Details of the tempered glass and tempered glass are described below.
　（強化用ガラス及び強化ガラス）
　強化用ガラスを構成するガラスは、例えば、イオン交換による化学強化が可能となる周知の組成を有するガラスを用いることができる。 (Tempered glass and tempered glass)
As the glass constituting the tempering glass, for example, a glass having a known composition that enables chemical strengthening by ion exchange can be used.
　このようなガラスとしては、例えば、ガラス組成として、質量％で、ＳｉＯ２　５０％～８０％、Ａｌ２Ｏ３　１％～２０％、Ｂ２Ｏ３　０％～２０％、Ｎａ２Ｏ　１％～２０％、Ｋ２Ｏ　０％～１５％、Ｌｉ２Ｏ　０％～１０％を含有するガラスが挙げられる。 As such glass, for example, the glass composition is SiO 2 50% to 80%, Al 2 O 3 1% to 20%, B 2 O 3 0% to 20%, and Na 2 O 1% in terms of mass %. 20%, K 2 O 0%-15%, Li 2 O 0%-10%.
　上記組成が好ましい理由を以下に示す。なお、各成分の含有範囲の説明において、％表示は、特に断りがない限り、質量％を示すものとする。 The reason why the above composition is preferable is shown below. In addition, in description of the content range of each component, % display shall show the mass % unless there is particular notice.
　ＳｉＯ２は、ガラスのネットワークを形成する成分である。ＳｉＯ２の含有量は、好ましくは５３％以上、より好ましくは５５％以上、さらに好ましくは６０％以上であり、好ましくは７８％以下、より好ましくは７５％以下、さらに好ましくは７２％以下である。ＳｉＯ２の含有量が上記下限値以上である場合、より一層ガラス化し易く、しかも耐酸性をより高めることができる。また、ＳｉＯ２の含有量が上記上限値以下である場合、溶融性や成形性をより一層向上させることができる。また、熱膨張係数が低くなりすぎないことから、周辺材料の熱膨張係数により一層整合させ易くすることができる。 SiO2 is a component that forms the network of glass. The content of SiO2 is preferably 53% or more, more preferably 55% or more, still more preferably 60% or more, preferably 78% or less, more preferably 75% or less, even more preferably 72% or less. . When the content of SiO 2 is equal to or higher than the above lower limit, vitrification is further facilitated, and acid resistance can be further enhanced. Moreover, when the content of SiO 2 is equal to or less than the above upper limit, the meltability and formability can be further improved. Also, since the coefficient of thermal expansion does not become too low, it is possible to more easily match the coefficient of thermal expansion of the surrounding materials.
　Ａｌ２Ｏ３は、イオン交換速度を高める成分であり、またヤング率を高めて硬度を高める成分である。Ａｌ２Ｏ３の含有量は、好ましくは３％以上、より好ましくは４％以上、さらに好ましくは５％以上であり、好ましくは１８％以下、より好ましくは１５％以下、さらに好ましくは１２％以下である。Ａｌ２Ｏ３の含有量が上記下限値以上である場合、イオン交換速度やヤング率をより一層高めることができ、更に、耐酸性をより一層向上させることができ、酸処理工程により適用し易くすることができる。また、Ａｌ２Ｏ３の含有量が上記上限値以下である場合、高温粘性を低くすることができ、溶融性をより一層向上させることができる。 Al 2 O 3 is a component that increases the ion exchange rate, and also a component that increases the Young's modulus and hardness. The content of Al 2 O 3 is preferably 3% or more, more preferably 4% or more, still more preferably 5% or more, preferably 18% or less, more preferably 15% or less, further preferably 12% or less. is. When the content of Al 2 O 3 is at least the above lower limit, the ion exchange rate and Young's modulus can be further improved, the acid resistance can be further improved, and the acid treatment process can be applied more easily. can do. Moreover, when the content of Al 2 O 3 is equal to or less than the above upper limit, the high-temperature viscosity can be lowered, and the meltability can be further improved.
　Ｂ２Ｏ３は、高温粘度や密度を低下させるとともに、耐失透性を高める成分である。Ｂ２Ｏ３の含有量は、特に限定されず、好ましくは１８％以下、より好ましくは１６％以下、さらに好ましくは１４％以下、特に好ましくは１２％以下である。Ｂ２Ｏ３の含有量が上記上限値以下である場合、イオン交換速度をより一層速めることができる。また、イオン交換によるガラス表面の着色をより一層抑制することができ、耐酸性や耐水性をより一層向上させることができる。 B 2 O 3 is a component that lowers high-temperature viscosity and density and increases devitrification resistance. The content of B 2 O 3 is not particularly limited, but is preferably 18% or less, more preferably 16% or less, still more preferably 14% or less, and particularly preferably 12% or less. When the B 2 O 3 content is equal to or less than the above upper limit, the ion exchange rate can be further increased. In addition, coloration of the glass surface due to ion exchange can be further suppressed, and acid resistance and water resistance can be further improved.
　Ｎａ２Ｏは、イオン交換成分であり、また高温粘度を低下させて、溶融性や成形性を高める成分である。また、Ｎａ２Ｏは、耐失透性を高める成分でもある。Ｎａ２Ｏの含有量は、特に限定されず、好ましくは２％以上、より好ましくは３％以上、さらに好ましくは５％以上であり、好ましくは１８％以下、より好ましくは１５％以下、さらに好ましくは１２％以下である。Ｎａ２Ｏの含有量が上記下限値以上である場合、溶融性や熱膨張係数をより一層高めることができ、イオン交換速度をより一層速めることができる。また、Ｎａ２Ｏの含有量が上記上限値以下である場合、耐酸性や耐失透性をより一層向上させることができる。 Na 2 O is an ion-exchange component and also a component that lowers high-temperature viscosity and enhances meltability and moldability. Na 2 O is also a component that enhances devitrification resistance. The content of Na 2 O is not particularly limited, and is preferably 2% or more, more preferably 3% or more, still more preferably 5% or more, preferably 18% or less, more preferably 15% or less, and even more preferably. is 12% or less. When the content of Na 2 O is at least the above lower limit, the meltability and thermal expansion coefficient can be further increased, and the ion exchange rate can be further increased. Moreover, when the content of Na 2 O is equal to or less than the above upper limit, acid resistance and devitrification resistance can be further improved.
　Ｋ２Ｏは、高温粘度を低下させて、溶融性や成形性を高める成分である。また、耐失透性やビッカース硬度を高める成分でもある。Ｋ２Ｏの含有量は、特に限定されず、好ましくは０．１％以上、より好ましくは１％以上、さらに好ましくは２％以上であり、好ましくは１０％以下、より好ましくは５％以下、さらに好ましくは３％未満である。Ｋ２Ｏの含有量が上記範囲内にある場合、耐酸性や耐失透性をより一層向上させることができる。 K 2 O is a component that lowers high-temperature viscosity and improves meltability and moldability. It is also a component that increases devitrification resistance and Vickers hardness. The content of K 2 O is not particularly limited, and is preferably 0.1% or more, more preferably 1% or more, still more preferably 2% or more, preferably 10% or less, more preferably 5% or less, More preferably less than 3%. When the K 2 O content is within the above range, the acid resistance and devitrification resistance can be further improved.
　Ｌｉ２Ｏは、イオン交換成分であり、高温粘度を低下させて、溶融性や成形性を高める成分である。また、ヤング率を高める成分である。さらに、Ｌｉ２Ｏは、イオン交換処理時に溶出して、イオン交換溶液を劣化させる成分でもある。よって、Ｌｉ２Ｏの含有量は、好ましくは０．０１％以上であり、好ましくは２％以下、より好ましくは１％以下、さらに好ましくは０．１％以下である。 Li 2 O is an ion-exchange component that lowers high-temperature viscosity and improves meltability and moldability. It is also a component that increases Young's modulus. Furthermore, Li 2 O is also a component that elutes out during the ion exchange treatment and deteriorates the ion exchange solution. Therefore, the content of Li 2 O is preferably 0.01% or more, preferably 2% or less, more preferably 1% or less, and still more preferably 0.1% or less.
　さらに、上記以外の成分として、下記の成分をガラス中に含有させることができる。 Furthermore, the following components can be included in the glass as components other than the above.
　ＭｇＯは、高温粘度を低下させて、溶融性や成形性を高める成分である。また、ヤング率を高めてビッカース硬度を高めたり、耐酸性を高めたりする成分でもある。ＭｇＯの含有量は、好ましくは０．１％以上、より好ましくは１％以上、さらに好ましくは２％以上であり、好ましくは４．５％以下、より好ましくは３％以下、さらに好ましくは２．５％以下である。ＭｇＯの含有量が上記範囲内にある場合、イオン交換速度をより一層速めることができ、しかもガラスをより失透し難くすることができる。 MgO is a component that lowers high-temperature viscosity and improves meltability and moldability. It is also a component that increases Young's modulus to increase Vickers hardness and acid resistance. The content of MgO is preferably 0.1% or more, more preferably 1% or more, still more preferably 2% or more, preferably 4.5% or less, more preferably 3% or less, further preferably 2.0% or more. 5% or less. When the content of MgO is within the above range, the ion exchange rate can be further increased, and the devitrification of the glass can be made more difficult.
　Ｐ２Ｏ５は、圧縮応力値を維持した上で、イオン交換速度を高める成分である。Ｐ２Ｏ５の含有量は、好ましくは２％以上、より好ましくは３．５％以上、さらに好ましくは４．５％以上であり、好ましくは８％以下、より好ましくは６％以下、さらに好ましくは５％以下である。Ｐ２Ｏ５の含有量が上記範囲内にある場合、耐水性をより一層向上させることができる。 P 2 O 5 is a component that increases the ion exchange rate while maintaining the compressive stress value. The content of P 2 O 5 is preferably 2% or more, more preferably 3.5% or more, still more preferably 4.5% or more, preferably 8% or less, more preferably 6% or less, still more preferably is 5% or less. When the content of P 2 O 5 is within the above range, water resistance can be further improved.
　強化用ガラスを構成するガラスには、清澄剤として、Ｃｌ、ＳＯ３、ＣｅＯ２を添加してもよく、Ｃｌ又はＳＯ３を添加することが好ましい。清澄剤の含有量は、例えば、０％以上、３％以下とすることができる。 Cl, SO 3 or CeO 2 may be added as a refining agent to the glass constituting the tempered glass, and Cl or SO 3 is preferably added. The content of the clarifier can be, for example, 0% or more and 3% or less.
　強化用ガラスを構成するガラスは、ＳｎＯ２を含有していてもよい。ＳｎＯ２は、イオン交換性能を高める効果を有する。ＳｎＯ２の含有量は、好ましくは０．０１％以上、より好ましくは０．０５％以上、さらに好ましくは０．１％以上であり、好ましくは３％以下である。 The glass constituting the tempering glass may contain SnO 2 . SnO2 has the effect of enhancing the ion exchange performance. The SnO 2 content is preferably 0.01% or more, more preferably 0.05% or more, still more preferably 0.1% or more, and preferably 3% or less.
　強化用ガラスを構成するガラス中におけるＦｅ２Ｏ３の含有量は、好ましくは１０００ｐｐｍ未満（０．１％未満）、より好ましくは４００ｐｐｍ未満、さらに好ましくは３００ｐｐｍ未満である。この場合、板厚１ｍｍにおける透過率（４００ｎｍ～７７０ｎｍ）をより一層向上させることができる。 The content of Fe 2 O 3 in the glass constituting the tempering glass is preferably less than 1000 ppm (less than 0.1%), more preferably less than 400 ppm, still more preferably less than 300 ppm. In this case, the transmittance (400 nm to 770 nm) at a plate thickness of 1 mm can be further improved.
　強化用ガラスを構成するガラス中におけるＮｂ２Ｏ５、Ｌａ２Ｏ３等の希土類酸化物の含有量は、好ましくは３％以下、より好ましくは１％以下、さらに好ましくは０．１％以下である。この場合、耐失透性をより一層向上させることができる。 The content of rare earth oxides such as Nb 2 O 5 and La 2 O 3 in the glass constituting the tempered glass is preferably 3% or less, more preferably 1% or less, and still more preferably 0.1% or less. be. In this case, devitrification resistance can be further improved.
　また、強化用ガラスを構成するガラスは、環境的配慮から、ガラス組成として、実質的にＡｓ２Ｏ３、Ｓｂ２Ｏ３、ＰｂＯを含有しないことが好ましい。また、環境的配慮から、実質的にＢｉ２Ｏ３、Ｆを含有しないことも好ましい。 Further, it is preferable that the glass constituting the tempering glass does not substantially contain As 2 O 3 , Sb 2 O 3 and PbO in terms of the glass composition. In addition, it is also preferable that substantially no Bi 2 O 3 or F is contained from environmental considerations.
　なお、本発明においては、上記のようなガラス組成となるように調合したガラスを加熱溶融し、リドロー法などにより熱成形して強化用ガラスを得ることができる。なお、ガラス原料の加熱溶融は、例えば、ガラス原料を連続溶融炉に投入して、１５００℃～１６００℃で加熱することにより行なうことができ、リドロー法による熱成形は、７６０℃～９５０℃で行うことができる。 In the present invention, the glass to be tempered can be obtained by heat-melting the glass prepared so as to have the glass composition described above and thermoforming the melt by a redraw method or the like. The heating and melting of the frit can be performed, for example, by putting the frit into a continuous melting furnace and heating it at 1500°C to 1600°C. It can be carried out.
　このようにして得られた強化用ガラスを化学強化することにより強化ガラスを製造することができる。化学強化法は、ガラスの歪点以下の温度でイオン交換処理により強化用ガラスの表面にイオン半径の大きいアルカリイオンを導入する方法である。化学強化法であれば、強化用ガラスの肉厚が薄くても、良好に圧縮応力層を形成し得るため、所望の機械的強度を得ることができる。 The tempered glass can be produced by chemically tempering the tempered glass thus obtained. The chemical strengthening method is a method of introducing alkali ions having a large ionic radius to the surface of the glass for strengthening by ion exchange treatment at a temperature below the strain point of the glass. With the chemical strengthening method, a compressive stress layer can be formed satisfactorily even if the thickness of the glass to be strengthened is thin, so that desired mechanical strength can be obtained.
　イオン交換処理の条件は、特に限定されず、強化用ガラスの粘度特性等を考慮して決定すればよい。特に、ＫＮＯ３溶融塩中のＫイオンを強化用ガラス中のＮａ成分とイオン交換すると、得られる強化ガラスの表面に圧縮応力層をより一層効率よく形成することができる。例えば、４００℃～５５０℃の硝酸カリウム溶液中に強化用ガラスを１時間～８時間浸漬することにより、イオン交換処理を行うことができる。 The conditions for the ion exchange treatment are not particularly limited, and may be determined in consideration of the viscosity characteristics of the tempering glass. In particular, when the K ions in the KNO3 molten salt are ion-exchanged with the Na component in the tempering glass, a compressive stress layer can be formed more efficiently on the surface of the obtained tempered glass. For example, the ion exchange treatment can be performed by immersing the tempering glass in a potassium nitrate solution at 400° C. to 550° C. for 1 hour to 8 hours.
　なお、強化用ガラスをイオン交換処理して得られる強化ガラスの組成は、イオン交換処理前の強化用ガラスの組成と同様の組成とすることができる。 The composition of the tempered glass obtained by subjecting the tempering glass to ion exchange treatment can be the same as the composition of the tempering glass before the ion exchange treatment.
１…強化用ガラス
１ａ…外表面
１ｂ…内表面
２…圧縮応力層
３…引張応力層
４…無応力層
１０…強化ガラス DESCRIPTION OF SYMBOLS 1... Glass for reinforcement 1a... Outer surface 1b... Inner surface 2... Compressive stress layer 3... Tensile stress layer 4... Non-stress layer 10... Tempered glass

Claims (6)

  1. 　ガラスを熱成形することにより、強化用ガラスを得る、成形工程と、
    　前記強化用ガラスを化学強化することにより、表面に圧縮応力層を有する強化ガラスを得る、強化工程と、
    　偏光顕微鏡によるクロスニコル観察によって、前記強化ガラスの表面に応力層が形成されていることを確認するとともに、前記強化ガラスの内部における無応力層の位置を確認することにより、化学強化の有無を判別する、判別工程と、
    を備える、強化ガラスの製造方法。     a forming step of thermoforming the glass to obtain a tempered glass;
    a strengthening step of chemically strengthening the tempering glass to obtain tempered glass having a compressive stress layer on its surface;
    Cross Nicol observation with a polarizing microscope confirms that a stress layer is formed on the surface of the tempered glass, and by confirming the position of the stress-free layer inside the tempered glass, the presence or absence of chemical strengthening is determined. a determination step;
    A method for producing tempered glass.
  2. 　前記強化ガラスが、対向している第１の主面及び第２の主面を有し、
    　前記判別工程において、前記強化ガラスの前記第１の主面に圧縮応力層が形成され、かつ前記第２の主面に引張応力層が形成されていることを確認するとともに、前記強化ガラスの厚み方向において前記圧縮応力層及び前記引張応力層の間に存在する前記無応力層の位置を確認することにより、化学強化の有無を判別する、請求項１に記載の強化ガラスの製造方法。     the tempered glass having first and second major surfaces facing each other;
    In the determination step, while confirming that a compressive stress layer is formed on the first main surface of the tempered glass and a tensile stress layer is formed on the second main surface, the thickness of the tempered glass The method for producing tempered glass according to claim 1, wherein the presence or absence of chemical strengthening is determined by confirming the position of the stress-free layer existing between the compressive stress layer and the tensile stress layer in a direction.
  3. 　前記判別工程において、前記強化ガラスの厚み方向中心位置よりも前記圧縮応力層側に、前記無応力層の厚み方向中心位置が存在することを確認することにより、化学強化がなされていると判別する、請求項１又は２に記載の強化ガラスの製造方法。 In the determination step, it is determined that chemical strengthening is performed by confirming that the center position in the thickness direction of the non-stress layer exists on the compressive stress layer side of the center position in the thickness direction of the tempered glass. , The method for producing tempered glass according to claim 1 or 2.
  4. 　偏光顕微鏡によるクロスニコル観察により、前記化学強化前の前記強化用ガラスの内部における無応力層の位置を確認する、確認工程をさらに備え、
    　前記判別工程において、前記強化ガラスの内部における前記無応力層の厚み方向中心位置が、前記化学強化前の前記強化用ガラスの内部における前記無応力層の厚み方向中心位置よりも前記圧縮応力層側にシフトしていることを確認することにより、化学強化がなされていると判別する、請求項１～３のいずれか１項に記載の強化ガラスの製造方法。     Further comprising a confirmation step of confirming the position of the stress-free layer inside the tempering glass before the chemical strengthening by cross-Nicol observation with a polarizing microscope,
    In the determination step, the thickness direction center position of the stress-free layer inside the tempered glass is closer to the compressive stress layer than the thickness direction center position of the stress-free layer inside the tempering glass before the chemical strengthening. The method for producing tempered glass according to any one of claims 1 to 3, wherein it is determined that chemical strengthening has been performed by confirming that the shift to .
  5. 　前記成形工程において、リドロー法により前記ガラスを熱成形する、請求項１～４のいずれか１項に記載の強化ガラスの製造方法。 The method for producing tempered glass according to any one of claims 1 to 4, wherein in the forming step, the glass is thermoformed by a redraw method.
  6. 　前記強化ガラスが、ガラス管であり、
    　前記強化工程において、前記ガラス管の外表面に前記圧縮応力層が形成されるように、前記強化用ガラスを化学強化する、請求項１～５のいずれか１項に記載の強化ガラスの製造方法。     The tempered glass is a glass tube,
    The method for producing tempered glass according to any one of claims 1 to 5, wherein in the tempering step, the tempering glass is chemically tempered so that the compressive stress layer is formed on the outer surface of the glass tube. .
PCT/JP2022/031820 2021-09-28 2022-08-24 Production method for strengthened glass WO2023053786A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001294442A (en) * 2000-02-10 2001-10-23 Sony Corp Glass panel for cathode-ray tube, cathode-ray tube using the same and manufacturing method of cathode-ray tube
JP2005174500A (en) * 2003-12-12 2005-06-30 Hoya Corp Manufacturing method of glass substrate for information recording medium
JP2014028730A (en) * 2012-07-31 2014-02-13 Asahi Glass Co Ltd Method for manufacturing a chemically strengthened glass and method for measuring the stress of a glass
JP2014040353A (en) * 2012-08-23 2014-03-06 Nippon Electric Glass Co Ltd Chemical strengthened crystallized glass product
JP2016536650A (en) * 2013-09-17 2016-11-24 コーニング インコーポレイテッド Broadband polarizer using ion-exchangeable fusion draw glass plate

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001294442A (en) * 2000-02-10 2001-10-23 Sony Corp Glass panel for cathode-ray tube, cathode-ray tube using the same and manufacturing method of cathode-ray tube
JP2005174500A (en) * 2003-12-12 2005-06-30 Hoya Corp Manufacturing method of glass substrate for information recording medium
JP2014028730A (en) * 2012-07-31 2014-02-13 Asahi Glass Co Ltd Method for manufacturing a chemically strengthened glass and method for measuring the stress of a glass
JP2014040353A (en) * 2012-08-23 2014-03-06 Nippon Electric Glass Co Ltd Chemical strengthened crystallized glass product
JP2016536650A (en) * 2013-09-17 2016-11-24 コーニング インコーポレイテッド Broadband polarizer using ion-exchangeable fusion draw glass plate

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