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WO2013031771A1 - Method for cutting reinforced glass - Google Patents

Method for cutting reinforced glass Download PDF

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Publication number
WO2013031771A1
WO2013031771A1 PCT/JP2012/071704 JP2012071704W WO2013031771A1 WO 2013031771 A1 WO2013031771 A1 WO 2013031771A1 JP 2012071704 W JP2012071704 W JP 2012071704W WO 2013031771 A1 WO2013031771 A1 WO 2013031771A1
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WO
WIPO (PCT)
Prior art keywords
tempered glass
cutting
initial
initial crack
cracks
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2012/071704
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French (fr)
Japanese (ja)
Inventor
齋藤　勲
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AGC Inc
Original Assignee
Asahi Glass Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Asahi Glass Co Ltd filed Critical Asahi Glass Co Ltd
Publication of WO2013031771A1 publication Critical patent/WO2013031771A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • C03C23/00—Other surface treatment of glass not in the form of fibres or filaments
    • C03C23/0005—Other surface treatment of glass not in the form of fibres or filaments by irradiation
    • C03C23/0025—Other surface treatment of glass not in the form of fibres or filaments by irradiation by a laser beam
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B33/00—Severing cooled glass
    • C03B33/09—Severing cooled glass by thermal shock
    • C03B33/091—Severing cooled glass by thermal shock using at least one focussed radiation beam, e.g. laser beam
    • 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
    • C03C21/001—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions
    • C03C21/002—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions to perform ion-exchange between alkali ions
    • 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
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
    • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal

Definitions

  • the present invention relates to a method for cutting tempered glass in which a compressive stress layer is formed on the surface of a sheet glass member.
  • a crack is formed in a direction substantially perpendicular to the surface of the brittle material substrate by rolling while pressing a cutter wheel or the like on the surface of the brittle material substrate.
  • a method of cutting by applying a mechanical pressing force in the vertical direction along the formed crack has been widely performed.
  • a brittle material substrate is cut using a cutter wheel, small fragments called cullets are generated, and the surface of the brittle material substrate may be damaged by the cullet.
  • microcracks are likely to occur at the edge of the brittle material substrate after cutting, and the brittle material substrate may be cracked due to the microcracks. For this reason, usually, after cutting, the surface and edges of the brittle material substrate are washed and polished to remove cullet and microcracks.
  • a method of cutting a brittle material substrate by internally heating the brittle material substrate at a temperature lower than the melting temperature by irradiation with a laser beam such as a CO 2 laser beam has been put into practical use.
  • the substrate surface is cut by irradiating the substrate surface with laser light and moving the irradiation position along the planned cutting line on the substrate surface.
  • part of the laser beam is absorbed by the substrate material, and the temperature inside the substrate becomes higher than that of the surroundings, so that compressive stress (thermal stress) acts due to thermal expansion.
  • the cutting can be started more stably if the initial crack is formed in advance at the site to be the cutting start point.
  • a method of forming such a crack it differs from a method of forming an initial crack on a substrate surface using a cutter wheel or the like, or a laser beam used for internal heating of a substrate as described in Patent Document 1.
  • An initial crack is formed in the vicinity of the substrate surface by condensing the laser beam in the wavelength region (for example, YAG laser light) in the vicinity of the substrate surface.
  • the wavelength region for example, YAG laser light
  • the object to be cut is tempered glass in which a compression stress layer is formed on the surface of the plate-like glass member
  • the laser beam is condensed near the surface of the plate-like glass member as in the method described in Patent Document 1.
  • the inventors of the present application have found that when the method for forming the initial crack is applied, the surface of the tempered glass may be cracked when the initial crack is formed. Further, the inventors of the present application have found that when cutting using internal heating after the formation of the initial crack, the tempered glass may be chipped, resulting in a problem of reduction in cutting accuracy.
  • An object of the present invention is to provide a method for cutting tempered glass having excellent cutting accuracy in order to solve the above-described problems in the prior art.
  • the present invention is a method of cutting tempered glass in which a compressive stress layer is formed on the surface of a sheet glass member, A step of condensing laser light to form an initial crack on the inner side of the compressive stress layer of the tempered glass, and after the formation of the initial crack, the tempered glass is internally heated, and the tempered glass is internally heated. A step of cutting the tempered glass by moving a portion to be cut along a planned cutting line, In the step of forming the initial crack, when the thickness of the tempered glass is t, the total length of the initial cracks in the thickness direction of the tempered glass is 0.2 t to 0.8 t.
  • a method for cutting tempered glass in which initial cracks are formed in at least two places where positions of the surface of the tempered glass in a plan view are substantially the same and positions in the thickness direction of the tempered glass are different.
  • a pulse laser beam having a wavelength range of 250 to 3000 nm and a peak power density of 1 ⁇ 10 12 to 1 ⁇ 10 16 W / m 2 is used. It is preferable.
  • pulsed laser light having a wavelength range of 250 to 3000 nm and a pulse width of 1000 ns or less in the initial crack forming step.
  • the initial crack forming step laser light is incident from an end face of the tempered glass, and the laser light is condensed on the inner side of the compressive stress layer of the tempered glass. It is preferable to form an initial crack.
  • the step of forming the initial crack it is preferable that at least two laser beams are simultaneously focused on the inner side of the tempered glass and the initial crack is simultaneously formed in at least two places. .
  • the method for cutting tempered glass of the present invention it is preferable to use laser light irradiation for internal heating of the tempered glass. Moreover, in the cutting method of the tempered glass of this invention, it is preferable to use discharge for the internal heating of the said tempered glass.
  • the cutting accuracy of the tempered glass is improved by using the present invention.
  • FIG. 1 is a schematic view showing a configuration example of tempered glass.
  • FIG. 2 is a schematic diagram showing the distribution of residual stress in the thickness direction (plate thickness direction) in the tempered glass 10 of FIG.
  • FIG. 3 is a schematic diagram showing the position of the initial crack inside the tempered glass.
  • FIG. 4 is a schematic diagram showing the position of the initial crack in the tempered glass in plan view.
  • FIG. 5 is a schematic diagram of an example in which the positions of the initial cracks in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10) are substantially the same.
  • FIG. 6 is a schematic diagram showing internal heating of tempered glass by electric discharge and cutting of tempered glass thereby.
  • FIG. 1 is a schematic view showing a configuration example of tempered glass.
  • compression stress layers 12a and 12b are formed on both main surfaces 11a and 11b of the plate-like glass member.
  • the compressive stress layer is a layer in which compressive stress remains by chemical treatment or heat treatment.
  • FIG. 2 is a schematic diagram showing the distribution of residual stress in the thickness direction (plate thickness direction) in the tempered glass 10 of FIG.
  • the compressive stress layers 12a and 12b existing on both main surfaces 11a and 11b of the tempered glass 10
  • the compressive stress remaining in the vicinity of the surface is the highest and tends to gradually decrease toward the inside.
  • tensile stress remains as a reaction against the compressive stress.
  • the maximum residual compressive stresses S1 and S2 in the compressive stress layers 12a and 12b are 100 to 1200 MPa, preferably 400 to 1000 MPa, more preferably 500 to 900 MPa in the case of ordinary chemically strengthened glass.
  • the thicknesses D1 and D2 of the compressive stress layers 12a and 12b are 5 to 100 ⁇ m, preferably 10 to 90 ⁇ m, and more preferably 20 to 80 ⁇ m in the case of ordinary chemically strengthened glass.
  • Examples of a method for forming the compressive stress layers 12a and 12b on both main surfaces of the tempered glass 10 include an air cooling strengthening method and a chemical strengthening method.
  • the air-cooled tempering method both the main surfaces 11a and 11b are rapidly cooled in a state in which the plate-like glass member forming the tempered glass 10 is maintained at a temperature near the softening point, and both the main surfaces 11a and 11b are connected to the inner side 13.
  • the compressive stress layers 12a and 12b are formed by making a temperature difference between the two.
  • the air cooling strengthening method is suitable for forming a compressive stress layer on a sheet glass member having a large thickness.
  • both the main surfaces 11a and 11b of the plate-like glass member forming the tempered glass 10 are ion-exchanged, and ions having a small ion radius (for example, Li ions and Na ions) contained in the glass are exchanged with a large ion radius.
  • ions for example, K ions
  • the chemical strengthening method is suitable for forming a compressive stress layer on a sheet glass member made of soda lime glass containing an alkali metal element.
  • the thickness of the plate-like glass member forming the tempered glass 10 is appropriately set according to the use of the tempered glass 10 or the like.
  • the tempered glass 10 has a thickness of 0.1 to 2.0 mm.
  • the thickness of the tempered glass 10 is preferably 0.3 to 1.8 mm, more preferably 0.5 to 1.5 mm.
  • composition of the tempered glass 10 is selected according to its application.
  • the tempered glass of the following composition is illustrated on an oxide basis.
  • Composition 1 expressed as mole percentage
  • the total content of SiO 2 and Al 2 O 3 is 75% or less
  • total MgO and CaO content MgO + CaO 7-15% total MgO + CaO 7-15%.
  • composition 2 mole percentage display
  • SiO 2 61-66%, Al 2 O 3 6-12%, MgO 7-13%, Na 2 O 9-17%, K 2 O 0-7% If it contains ZrO 2 , its content is 0.8% or less.
  • Composition 3 In percentage by mass
  • SiO 2 is 75.5 to 85.5%
  • MgO is 1 to 8%
  • CaO is 0 to 7%
  • Al 2 O 3 is 0 to 5%
  • Na 2 O 10 to 22.5%
  • the content of MgO is greater than the content of CaO
  • the total content of MgO and CaO (MgO + CaO) is 8% or less
  • the total content of MgO, CaO and Na 2 O is 24
  • the ratio obtained by dividing the MgO and CaO content (MgO + CaO) by the Na 2 O content is 0.45 or less.
  • a laser beam is applied to the inner side (hereinafter referred to as the inner side of the tempered glass in this specification) 13 of the tempered glass 10 from the compressive stress layers 12a and 12b. Concentrate to form initial cracks.
  • the cracks are caused to self-run due to structural relaxation due to the formation of initial cracks.
  • the surface of the tempered glass is easily cracked. Even when the surface does not crack, the cullet may scatter and adhere to the surface of the tempered glass when the initial crack is formed.
  • FIG. 3 is a view of the tempered glass 10 as viewed from the end face side, and FIG. 4 shows the main surface 11a of the tempered glass 10.
  • FIG. 3 initial cracks 20 a and 20 b are formed on the inner side 13 of the tempered glass 10 at two different positions in the thickness direction of the tempered glass 10.
  • FIG. 4 the positions of the initial cracks 20a and 20b in plan view of the main surface 11a of the tempered glass 10 are the same.
  • the reason why initial cracks are formed on the inner side 13 of the tempered glass 10 in at least two places where the positions in the thickness direction of the tempered glass 10 are different is as follows. As described above, when initial cracks are formed in the compressive stress layers 12a and 12b of the tempered glass 10, the cracks are free-running due to structural relaxation due to the formation of the initial cracks, and the surface of the tempered glass may be cracked. On the other hand, when an initial crack is formed on the inner side 13 of the tempered glass 10, the structural relaxation due to the formation of the initial crack is extremely small, so that the cracks are not self-propelled and the tempered glass is not cracked.
  • the tempered glass 10 when only one initial crack is formed on the inner side 13 of the tempered glass 10, when the tempered glass 10 is cut by internal heating performed subsequent to the formation of the initial crack, the tempered glass 10 has the following reasons. Chipping may occur. When only one initial crack is formed on the inner side 13 of the tempered glass 10, the length of the initial crack in the thickness direction of the tempered glass 10 is shortened. Therefore, the tempered glass is formed by internal heating performed after the formation of the initial crack. In order to cut 10, it is necessary to form an initial crack on the surface side of the tempered glass 10, that is, at a position close to the compressive stress layers 12 a and 12 b.
  • the length of the initial crack in the thickness direction of the tempered glass 10 is short, so that the initial crack when the tempered glass 10 is viewed from the end surface side is reduced.
  • the tempered glass 10 is internally heated, cracks develop in the surface direction of the tempered glass 10 (main surface 11a, 11b direction) without progressing in the thickness direction of the tempered glass 10, There is a risk of chipping in the tempered glass 10.
  • the initial crack is formed in at least two places where the positions in the thickness direction of the tempered glass 10 are different from the inner side 13 of the tempered glass 10, the total length of the initial cracks in the thickness direction of the tempered glass 10 Therefore, the cross-sectional area of the initial crack when the tempered glass 10 is viewed from the end surface side is larger than the cross-sectional area of the initial crack in the plan view of the main surface 11a of the tempered glass 10.
  • the tempered glass 10 is internally heated, cracks progress in the thickness direction of the tempered glass 10, so that the cutting accuracy of the tempered glass 10 is excellent.
  • the initial cracks 20 a and 20 b are formed near the upper end and the lower end of the inner side 13 of the tempered glass 10, but the position where the initial crack is formed is not limited to this.
  • the position where the initial crack is formed may be the inner side 13 of the tempered glass 10 and the position where the initial cracks in the thickness direction of the tempered glass 10 are different from each other. Therefore, all of the initial cracks may be formed at a position near the upper end of the inner side 13 of the tempered glass 10, may be formed at a position near the lower end, or may be formed near the center.
  • the initial crack may be formed near the upper end and near the center of the inner side 13 of the tempered glass 10, or may be formed near the lower end and near the center.
  • the cracks may be formed at a position near the upper end of the inner side 13 of the tempered glass 10, near the center, and near the lower end.
  • a part of the crack may be applied to the compressive stress layers 12a and 12b.
  • the compressive stress remaining in the compressive stress layers 12 a and 12 b is extremely small at a position close to the inner side 13 of the tempered glass 10. Even if a part of the initial crack formed at a position close to the lower end is applied to the compressive stress layers 12a and 12b, it is considered that the influence of the crack can be ignored.
  • the initial cracks formed on the inner side 13 of the tempered glass 10 may be close to each other in the thickness direction of the tempered glass 10. Further, even if the initial cracks formed on the inner side 13 of the tempered glass 10 are connected to each other and seemingly appear as a single initial crack, it does not depart from the spirit of the present invention.
  • the length of the initial crack in the thickness direction of the tempered glass 10 serves as a starting point for cutting the tempered glass 10 by internal heating, the length of the initial crack in the thickness direction of the tempered glass 10, more specifically, It is considered that the cutting accuracy of the tempered glass 10 is improved as the total length of the initial cracks in the thickness direction of the glass 10 is longer. However, if the total length of the initial cracks is too long with respect to the thickness of the tempered glass 10, the initial cracks reach close to the surface of the tempered glass 10 (main surfaces 11a, 11b). There is a risk of cracking.
  • the tempered glass 10 may be chipped for the following reasons.
  • the total length of initial cracks in the thickness direction of the tempered glass 10 is 0.2 t to 0.8 t.
  • the internal heating performed following the formation of the initial cracks causes the cracks to start cutting the tempered glass 10. Even if it does not start or the progress of cracks starts, the tempered glass 10 may be chipped for the following reason.
  • the total length of initial cracks formed on the inner side 13 of the tempered glass 10 is shorter than 0.2 t, the total length of initial cracks in the thickness direction of the tempered glass 10 is short.
  • the total length of the initial cracks formed on the inner side 13 of the tempered glass 10 is shorter than 0.2 t, the total length of the initial cracks in the thickness direction of the tempered glass 10 is short.
  • the cross-sectional area of the initial cracks when the tempered glass 10 is viewed from the end face side is The cross-sectional area of the initial crack in plan view of the main surface 11a is larger.
  • the total length of the initial cracks formed on the inner side 13 of the tempered glass 10 is longer than 0.8 t, the initial crack reaches near the surface (main surfaces 11a, 11b) of the tempered glass 10, and Since there is a risk of cracking on the surface, the total length of the initial cracks needs to be 0.8 t or less.
  • the total length of the initial cracks formed on the inner side 13 of the tempered glass 10 is preferably 0.25 t to 0.75 t, and more preferably 0.3 t to 0.7 t.
  • the initial cracks formed on the inner side 13 of the tempered glass 10 are as seen in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10), as shown in FIG. It is necessary that the initial cracks 20a and 20b have the same position.
  • the reason why the initial crack is formed on the inner side 13 of the tempered glass 10 is that it is used as a starting point of cutting when the tempered glass is subsequently cut by internal heating. For this reason, if there is a shift in the position of the initial crack in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10), the cutting accuracy may be lowered.
  • the initial crack is formed by condensing the laser beam, it may be difficult to accurately control the position where the initial crack is formed. For this reason, it may be difficult to completely match the positions of the initial cracks in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10).
  • the position of the initial crack in a plan view of the tempered glass 10 is in perfect agreement as long as the cutting accuracy of the tempered glass by subsequent internal heating is not adversely affected. It does not have to be, and it is sufficient if it is substantially the same.
  • FIG. 5 is a schematic diagram of an example in which the positions of the initial cracks in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10) are substantially the same.
  • the initial cracks 20 a and 20 b are present at positions slightly shifted along the planned cutting line 30.
  • a line connecting the centers of the initial cracks 20a and 20b exists on the planned cutting line 30, and the directions of both coincide with each other. If the initial cracks 20a and 20b are in such a positional relationship, the cutting accuracy of the tempered glass due to internal heating will not be adversely affected.
  • the initial crack is formed by condensing the laser beam, it may be difficult to accurately control the position where the initial crack is formed.
  • the centers of the initial cracks 20 a and 20 b exist on the planned cutting line 30, but the laser beam is condensed to form the initial crack, and therefore the initial crack center does not exist on the planned cutting line.
  • the initial crack center does not exist on the planned cutting line.
  • at least a part of the initial crack needs to exist on the planned cutting line. Even when the positions of the initial cracks are deviated, at least a part of both needs to be covered.
  • the initial crack formed on the inner side 13 of the tempered glass 10 serves as a starting point for cutting the tempered glass 10 by internal heating, it is preferably formed at a position close to the starting point of the planned cutting line 30 of the tempered glass 10. Since the illustrated mode assumes a case where the tempered glass is completely cut (full cut processing), the starting point of the planned cutting line 30 is the end of the tempered glass 10. For this reason, the position of the initial crack in a plan view of the tempered glass 10 (a plan view of the main surface 11 a of the tempered glass 10) is preferably a position within 5 mm from the end of the tempered glass 10.
  • the formed initial crack 10 reaches the end surface of the tempered glass 10 and is strengthened. There is a possibility that the glass 10 is cracked. For this reason, the position of the initial crack in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10) is preferably separated from the end of the tempered glass 10 by 0.2 mm or more.
  • the starting point of the planned cutting line 30 is the end of the tempered glass 10.
  • the starting point of the planned cutting line 30 may be other than the end of the tempered glass 10.
  • the position of the initial crack in a plan view of the tempered glass 10 is preferably a position within 5 mm from the starting point of the planned cutting line 30.
  • the wavelength range is 250 to 3000 nm and the peak power density is 1 ⁇ 10. It is preferable to use a pulse laser beam of 12 to 1 ⁇ 10 16 W / m 2 .
  • Laser light having a wavelength range of 250 to 3000 nm is transmitted through the tempered glass having the above-described composition to some extent. Therefore, when the power density of the laser light is low, the laser beam is focused on the inner side 13 of the tempered glass 10 at the initial stage. No cracks are formed. However, when the power density is increased and a certain threshold value is exceeded, nonlinear absorption of the laser light occurs. In the method for cutting tempered glass of the present invention, initial cracks are formed on the inner side 13 of the tempered glass 10 by utilizing nonlinear absorption of laser light.
  • nonlinear absorption of laser light having a wavelength region of 250 to 3000 nm occurs. Cracks can be formed.
  • the peak power density is less than 1 ⁇ 10 12 W / m 2 , initial cracks cannot be formed on the inner side 13 of the tempered glass 10 due to nonlinear absorption of laser light having a wavelength range of 250 to 3000 nm.
  • the peak power density is more than 1 ⁇ 10 16 W / m 2 , the tempered glass 10 may be cracked when the laser light is collected.
  • the peak power density of the pulsed laser beam is preferably 1 ⁇ 10 13 to 1 ⁇ 10 15 W / m 2 .
  • the laser beam having a wavelength range that passes through the tempered glass having the above-described composition to some extent is used when the laser beam having a wavelength range absorbed by the tempered glass is used. This is because the laser light is absorbed by the compressive stress layer existing on the surface of the tempered glass, the laser light cannot be condensed on the inner side of the tempered glass, and initial cracks cannot be formed on the inner side of the tempered glass.
  • the laser beam having a wavelength range that transmits the tempered glass having the above-described composition to some extent it is more preferable to use a laser beam having a wavelength range of 300 to 2000 nm, and it is further preferable to use a laser beam having a wavelength range of 350 to 1500 nm. preferable.
  • the wavelength range is 250 to 3000 nm in order to focus the laser beam and form an initial crack on the inner side 13 of the tempered glass 10.
  • pulsed laser light having a pulse width of 1000 ns or less. If the pulse laser light has a pulse width of 1000 ns or less, nonlinear absorption of laser light having a wavelength region of 250 to 3000 nm occurs, so that an initial crack can be formed on the inner side 13 of the tempered glass 10.
  • the pulse width of the pulse laser beam is more preferably 500 ns or less, and further preferably 200 ns or less.
  • the laser beam is focused on the inner side of the tempered glass to form initial cracks.
  • Laser light may be condensed.
  • at least two laser lights can be simultaneously focused on the inner side of the tempered glass, and initial cracks can be simultaneously formed in at least two places.
  • the tempered glass is internally heated to cut the tempered glass. More specifically, the tempered glass is cut by moving a portion of the tempered glass that is heated inside along a planned cutting line.
  • a method for internally heating the tempered glass a method using discharge or a method of irradiating laser light is preferably used as described below.
  • FIG. 6 is a schematic diagram showing internal heating of tempered glass by electric discharge and cutting of tempered glass thereby.
  • the discharge electrode 100 and the counter electrode 200 are separated by a predetermined interval.
  • the tempered glass 10 to be cut is disposed between the discharge electrode 100 and the counter electrode 200.
  • the discharge electrode 100 and the counter electrode 200 are connected to an AC power source 300.
  • the counter electrode 200 may not be provided.
  • a discharge 400 is formed between the discharge electrode 100 and the main surface 11a of the tempered glass 10 facing the discharge electrode 100.
  • a discharge is also formed between the counter electrode 200 and the main surface 11 b of the tempered glass 10 facing the counter electrode 200.
  • the discharge electrode 100 is located above the planned cutting line 30 of the tempered glass 10 and moves in the direction of the arrow along the planned cutting line 30.
  • the movement referred to here is a relative movement between the discharge electrode 100 and the tempered glass 10, and the tempered glass 10 instead of the discharge electrode 100 may move in the direction opposite to the arrow.
  • the discharge electrode 100 is located above the initial stage crack (not shown) formed in the inner side of the tempered glass 10.
  • the portion of the tempered glass 10 where the discharge 400 is formed that is, the portion immediately below the discharge electrode 100 is internally heated by the discharge, and its temperature becomes higher than that of the surroundings.
  • a tensile stress acts in a direction perpendicular to the planned cutting line 30 behind the discharge electrode 100 in the moving direction, and a crack 40 is formed in the tempered glass 10.
  • the portion of the tempered glass 10 that is internally heated also moves along the planned cutting line 30, and the crack 40 is the longitudinal length of the tempered glass 10. Progressing over the entire direction, the tempered glass 10 is cut.
  • the discharge electrode 100 and the counter electrode 200 are preferably materials that are excellent in conductivity, have a high melting point, and are not easily oxidized.
  • Specific examples of such materials include noble metals such as gold, platinum and palladium or alloys thereof, and platinum or palladium or alloys thereof are particularly preferable.
  • the distance between the discharge electrode 100 and the main surface 11a of the tempered glass 10 is not particularly limited as long as the discharge 400 can be formed between the discharge electrode 100 and the main surface 11a of the tempered glass 10, but 0 mm to 10 cm. It is preferably 0 mm to 10 mm, more preferably 0.05 mm to 5 mm.
  • 0 mm means a state in which the discharge electrode 100 and the main surface 11a of the tempered glass 10 are in contact.
  • the distance between the counter electrode 200 and the main surface 11b of the tempered glass 10 is the same as described above.
  • the AC power supply 300 is not particularly limited as long as it can generate a high-frequency AC current that can form the discharge 400.
  • Specific examples include a high-frequency AC power source using a resonant transformer such as a Tesla transformer, a flyback transformer, a high-output high-frequency generator, and a high-frequency semiconductor chopper.
  • the AC power supply 300 has a voltage of 10 V to 10 7 V, more preferably 100 V to 10 6 V, still more preferably 100 V to 10 5 V, and a frequency of 1 kHz to 10 GHz, more preferably 10 kHz to 1 GHz, still more preferably 100 kHz to It is preferable to generate a high frequency alternating current of 100 MHz.
  • the discharge electrode 100, the counter electrode 200, and the tempered glass 10 positioned between them are in a nitrogen atmosphere, an argon atmosphere or six at a pressure of 1 Pa to 100 MPa, more preferably 1 kPa to 1 MPa. It is preferable to place under a sulfur fluoride atmosphere.
  • the discharge electrode 100 is moved in the direction of the arrow along the planned cutting line 30 of the tempered glass 10.
  • the part that is heated inside the tempered glass 10 is also moved along the planned cutting line 30.
  • the tempered glass is internally heated by irradiating the laser beam
  • the laser beam used for internal heating of the tempered glass 10 is not particularly limited as long as the tempered glass 10 can be internally heated by irradiation.
  • the wavelength of the laser light is preferably 250 to 5000 nm for internally heating the tempered glass 10 by irradiation.
  • the wavelength of the laser beam is more preferably 300 to 4000 nm, still more preferably 800 to 3000 nm.
  • Examples of the light source of the laser beam in the above wavelength range include a UV laser (wavelength: 355 nm), a green laser (wavelength: 532 nm), a semiconductor laser (wavelength: 808 nm, 940 nm, 975 nm), and a fiber laser (wavelength: 1060 to 1100 nm). ), YAG laser (wavelengths: 1064 nm, 2080 nm, 2940 nm) and the like.
  • the laser light oscillation method is not limited, and any of a CW laser that continuously oscillates laser light and a pulse laser that intermittently oscillates laser light can be used.
  • the intensity distribution of the laser beam is not limited, and may be a Gaussian type or a top hat type. Even when the tempered glass is internally heated by laser beam irradiation, the tempered glass 10 may be cooled behind the laser beam irradiation site along the planned cutting line 30.
  • a cover glass (protective glass) is often used in order to enhance the protection and aesthetics of a display (including a touch panel).
  • a glass substrate is widely used as a display substrate.
  • the reduction in thickness and weight of portable devices has progressed, and the glass used in portable devices has become thinner. Since the strength decreases as the glass becomes thinner, tempered glass having a front surface layer and a back surface layer in which compressive stress remains has been developed to compensate for the insufficient strength of the glass. Tempered glass is also used as automotive window glass and architectural window glass. The present invention is suitable for cutting tempered glass used for such a wide range of applications.
  • the tempered glass to be cut is as follows. Dimensions: 50mm long x 50mm wide x 0.9mm thick Composition (wt% Display): SiO 2 64.5%, Al 2 O 3 6.0%, 11.0% MgO, Na 2 O 12.0%, K 2 O 4%, ZrO 2 2.5% Compressive stress layer: Maximum residual compressive stress 656 MPa, layer thickness 67 ⁇ m (Example 1)
  • the initial crack was formed by condensing the pulse laser beam at two locations (surface side and back side) where the positions in the thickness direction of the tempered glass differed on the inner side of the tempered glass.
  • the pulse laser light used is as follows.
  • the length of the initial crack in the thickness direction of the tempered glass was 0.14 mm (surface side) and 0.20 mm (back side).
  • the thickness of the tempered glass is t (mm)
  • the total length of the initial cracks corresponds to 0.38 t.
  • the tempered glass was cut by internal heating.
  • the following laser beam irradiation was used for internal heating of the tempered glass.
  • Light source Fiber laser (central wavelength band: 1070 nm) Beam diameter: 0.2mm Scanning speed: 2.5 mm / sec (scanned along the planned cutting line from the end face side of the tempered glass)
  • Output 150-200W
  • Example 2 The same procedure as in Example 1 was performed except that the position where the pulse laser beam was focused was changed so that the position of the initial crack (back side) formed in the thickness direction of the tempered glass was different from that in Example 1. did.
  • the position of the initial crack in plan view of the tempered glass was the same as the formed initial crack, and the position was 0.2 mm from the end of the tempered glass.
  • the position in the thickness direction of tempered glass was 0.15 mm (surface side) and 0.45 mm (back side) in the distance from the surface of tempered glass to the lower end of the initial crack.
  • the length of the initial crack in the thickness direction of the tempered glass was 0.14 mm (surface side) and 0.20 mm (back side).
  • the total length of the initial cracks corresponds to 0.38 t.
  • the tempered glass was cut by internal heating in the same procedure as in Example 1. As a result, it was possible to cut the tempered glass with excellent cutting accuracy without causing chipping or the like.
  • Example 1 The same procedure as in Example 1 was carried out except that the initial crack was formed by condensing the pulse laser beam only at one location (surface side) inside the tempered glass.
  • the position of the initial crack in plan view of the tempered glass was the same as the formed initial crack, and the position was 0.2 mm from the end of the tempered glass.
  • the position in the thickness direction of the tempered glass was 0.15 mm as a distance from the surface of the tempered glass to the lower end of the initial crack.
  • the length of the initial crack in the thickness direction of the tempered glass was 0.14 mm.
  • the tempered glass was cut by internal heating in the same procedure as in Example 1. When the thickness of the tempered glass is t (mm), the length of the initial crack corresponds to 0.16 t. As a result, the tempered glass was chipped and the cutting accuracy was low.
  • An initial crack was formed by condensing the pulse laser beam at five locations inside the tempered glass.
  • the pulse laser light used is as follows. Wavelength: 532nm Peak power density: 1.3 ⁇ 10 14 W / m 2 Pulse width: 33ns Theoretical light collection diameter: 5.7 ⁇ m
  • the position of the initial crack in plan view of the tempered glass was the same as the formed initial crack, and the position was 0.2 mm from the end of the tempered glass. Further, the positions in the thickness direction of the tempered glass were 0.15 mm, 0.3 mm, 0.45 mm, 0.6 mm, and 0.75 mm, respectively, as distances from the surface of the tempered glass to the lower end of the initial crack.
  • the length of the initial crack in the thickness direction of the tempered glass was 0.74 mm, with five cracks connected.
  • the thickness of the tempered glass is t (mm)
  • the length of the initial crack corresponds to 0.82 t.
  • the tempered glass was chipped after the initial crack was created and could not be cut.

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Abstract

The present invention provides a method for cutting reinforced glass, which has compressive stress layers formed on the surface of a plate shaped glass member. The method for cutting reinforced glass includes a step for forming initial cracks by concentrating laser light on portions of the reinforced glass more inward than the compressive stress layers and a step for cutting the reinforced glass by heating the inside of the reinforced glass after forming the initial cracks and moving a part of the reinforced glass being heated internally along a line to be cut. In the step for forming the initial cracks, initial cracks are formed in at least two locations that have substantially the same position when viewed in a plane view of the surface of the reinforced glass and differ in position in the direction of thickness of the reinforced glass. This cutting method for reinforced glass has superior cutting precision.

Description

強化ガラスの切断方法How to cut tempered glass

　本発明は、板状ガラス部材の表面に圧縮応力層が形成された強化ガラスの切断方法に関する。 The present invention relates to a method for cutting tempered glass in which a compressive stress layer is formed on the surface of a sheet glass member.

　従来、ガラス基板のような脆性材料基板の切断方法としては、脆性材料基板の表面にカッターホイール等を圧接させながら転動させて、脆性材料基板の表面に対して略垂直方向のクラックを形成し、形成されたクラックに沿って垂直方向に機械的な押圧力を加えて切断する方法が広く行われていた。 Conventionally, as a method for cutting a brittle material substrate such as a glass substrate, a crack is formed in a direction substantially perpendicular to the surface of the brittle material substrate by rolling while pressing a cutter wheel or the like on the surface of the brittle material substrate. A method of cutting by applying a mechanical pressing force in the vertical direction along the formed crack has been widely performed.

　しかし、通常、カッターホイールを用いて脆性材料基板の切断を行った場合、カレットと呼ばれる小破片が発生し、このカレットによって脆性材料基板の表面にキズがつくことがあった。また、切断後の脆性材料基板の端部にはマイクロクラックが生じやすく、このマイクロクラックを起因として脆性材料基板の割れが発生することがあった。このため、通常は切断後に、脆性材料基板の表面及び端部を洗浄及び研磨して、カレットやマイクロクラック等を除去していた。 However, usually, when a brittle material substrate is cut using a cutter wheel, small fragments called cullets are generated, and the surface of the brittle material substrate may be damaged by the cullet. In addition, microcracks are likely to occur at the edge of the brittle material substrate after cutting, and the brittle material substrate may be cracked due to the microcracks. For this reason, usually, after cutting, the surface and edges of the brittle material substrate are washed and polished to remove cullet and microcracks.

　近年、ＣＯ2レーザビーム等のレーザ光照射により、溶融温度未満で脆性材料基板を内部加熱して、脆性材料基板を切断する方法が実用化されつつある。この方法では、基板表面にレーザ光を照射し、その照射位置を基板表面の切断予定線に沿って移動させることで基板を切断する。レーザ光照射位置では、レーザ光の一部が基板材料に吸収され、基板内部の温度が周囲に比べて高温になるので、熱膨張により圧縮応力（熱応力）が作用する。その反作用として、レーザ光の照射位置の移動方向後方では予定線と直交する方向に引張応力が作用し、基板が切断される。この方法では、熱応力を利用するため、工具を直接、基板に接触させることがなく、切断面はマイクロクラック等の少ない平滑な面となり、基板の強度が維持される。すなわち、レーザ光照射を用いた切断方法は、非接触加工であるため、上記した潜在的欠陥の発生が抑えられ、切断を行った際に脆性材料基板に発生する割れ等の損傷が抑えられる。レーザ光照射を用いた切断方法は、例えば、特許文献１に開示されている。
　基板の内部加熱を利用して脆性材料基板を切断する方法としては、特許文献２に記載されているような、基板の内部加熱に放電を用いる方法もある。 In recent years, a method of cutting a brittle material substrate by internally heating the brittle material substrate at a temperature lower than the melting temperature by irradiation with a laser beam such as a CO 2 laser beam has been put into practical use. In this method, the substrate surface is cut by irradiating the substrate surface with laser light and moving the irradiation position along the planned cutting line on the substrate surface. At the laser beam irradiation position, part of the laser beam is absorbed by the substrate material, and the temperature inside the substrate becomes higher than that of the surroundings, so that compressive stress (thermal stress) acts due to thermal expansion. As the reaction, tensile stress acts in the direction orthogonal to the planned line behind the moving direction of the irradiation position of the laser beam, and the substrate is cut. In this method, since the thermal stress is used, the tool is not directly brought into contact with the substrate, the cut surface becomes a smooth surface with few microcracks and the strength of the substrate is maintained. That is, since the cutting method using laser light irradiation is non-contact processing, the occurrence of the above-described latent defects is suppressed, and damage such as cracks generated in the brittle material substrate when cutting is suppressed. A cutting method using laser light irradiation is disclosed in Patent Document 1, for example.
As a method of cutting a brittle material substrate using internal heating of the substrate, there is a method of using discharge for internal heating of the substrate as described in Patent Document 2.

　基板の内部加熱を利用して脆性材料基板を切断する場合、切断の開始点となる部位に予め初期クラックを形成した方が、安定的に切断を開始できる。このようなクラックを形成する方法としては、カッターホイール等を用いて基板表面に初期クラックを形成する方法や、特許文献１に記載されているように、基板の内部加熱に用いるレーザ光とは異なる波長域のレーザ光（例えば、ＹＡＧレーザ光）基板表面近傍に集光させることで、基板表面近傍に初期クラックを形成する。
　しかしながら、カッターホイール等を用いて基板表面に初期クラックを形成すると、カッターホイールを用いて脆性材料基板を切断する場合と同様の問題を生じるおそれがある。すなわち、初期クラックの形成時にカレットと呼ばれる小破片が発生し、このカレットによって脆性材料基板の表面にキズがつくことがある。
　これに対し、特許文献１に記載の方法では、レーザ光の集光により基板表面近傍に初期クラックを形成するため、初期クラックの形成時にカレットが発生するおそれがない。また、特許文献１に記載の方法では、初期クラックの寸法を小さくすることにより、切断精度を向上させることができる。 When the brittle material substrate is cut using the internal heating of the substrate, the cutting can be started more stably if the initial crack is formed in advance at the site to be the cutting start point. As a method of forming such a crack, it differs from a method of forming an initial crack on a substrate surface using a cutter wheel or the like, or a laser beam used for internal heating of a substrate as described in Patent Document 1. An initial crack is formed in the vicinity of the substrate surface by condensing the laser beam in the wavelength region (for example, YAG laser light) in the vicinity of the substrate surface.
However, if an initial crack is formed on the substrate surface using a cutter wheel or the like, the same problem as when cutting a brittle material substrate using the cutter wheel may occur. That is, small fragments called cullet are generated during the formation of the initial crack, and the cullet may scratch the surface of the brittle material substrate.
On the other hand, in the method described in Patent Document 1, since an initial crack is formed in the vicinity of the substrate surface by condensing laser light, there is no possibility that cullet is generated when the initial crack is formed. In the method described in Patent Document 1, the cutting accuracy can be improved by reducing the size of the initial crack.

日本国特開２００７－２６０７４９号公報Japanese Laid-Open Patent Publication No. 2007-260749 日本国特開２００４－１４８４３８号公報Japanese Unexamined Patent Publication No. 2004-148438

　しかしながら、切断対象が板状ガラス部材の表面に圧縮応力層が形成された強化ガラスの場合、特許文献１に記載の方法のような、板状ガラス部材の表面近傍にレーザ光を集光して初期クラックを形成する方法を適用すると、初期クラックの形成時に強化ガラスの表面に割れが生じるおそれがあることを本願発明者らは見出した。また、初期クラックの形成後、内部加熱を利用して切断する際に、強化ガラスに欠けが生じるなど、切断精度の低下が問題となるおそれがあることを本願発明者らは見出した。 However, when the object to be cut is tempered glass in which a compression stress layer is formed on the surface of the plate-like glass member, the laser beam is condensed near the surface of the plate-like glass member as in the method described in Patent Document 1. The inventors of the present application have found that when the method for forming the initial crack is applied, the surface of the tempered glass may be cracked when the initial crack is formed. Further, the inventors of the present application have found that when cutting using internal heating after the formation of the initial crack, the tempered glass may be chipped, resulting in a problem of reduction in cutting accuracy.

　本発明は、上記した従来技術における問題点を解決するため、切断精度に優れた強化ガラスの切断方法を提供することを目的とする。 An object of the present invention is to provide a method for cutting tempered glass having excellent cutting accuracy in order to solve the above-described problems in the prior art.

　上記した目的を達成するため、本発明は、板状ガラス部材の表面に圧縮応力層が形成された強化ガラスを切断する方法であって、
　前記強化ガラスの前記圧縮応力層よりも内部側に、レーザ光を集光して初期クラックを形成する工程、および、初期クラックの形成後、前記強化ガラスを内部加熱し、前記強化ガラスの内部加熱される部位を切断予定線に沿って移動させることにより、前記強化ガラスを切断する工程を含み、
　前記初期クラックを形成する工程では、前記強化ガラスの厚さをｔとするとき、該強化ガラスの厚さ方向における前記初期クラックの合計長さが、０．２ｔ～０．８ｔとなるように、前記強化ガラスの表面の平面視での位置が略同一であって、かつ、前記強化ガラスの厚さ方向における位置が異なる少なくとも２個所に初期クラックを形成する、強化ガラスの切断方法を提供する。 In order to achieve the above-described object, the present invention is a method of cutting tempered glass in which a compressive stress layer is formed on the surface of a sheet glass member,
A step of condensing laser light to form an initial crack on the inner side of the compressive stress layer of the tempered glass, and after the formation of the initial crack, the tempered glass is internally heated, and the tempered glass is internally heated. A step of cutting the tempered glass by moving a portion to be cut along a planned cutting line,
In the step of forming the initial crack, when the thickness of the tempered glass is t, the total length of the initial cracks in the thickness direction of the tempered glass is 0.2 t to 0.8 t. Provided is a method for cutting tempered glass, in which initial cracks are formed in at least two places where positions of the surface of the tempered glass in a plan view are substantially the same and positions in the thickness direction of the tempered glass are different.

　本発明の強化ガラスの切断方法において、前記初期クラックの形成工程では、波長域が２５０～３０００ｎｍ、かつ、ピークパワー密度が１×１０12～１×１０16Ｗ／ｍ2のパルスレーザ光を用いることが好ましい。 In the method for cutting tempered glass of the present invention, in the step of forming the initial crack, a pulse laser beam having a wavelength range of 250 to 3000 nm and a peak power density of 1 × 10 12 to 1 × 10 16 W / m 2 is used. It is preferable.

　本発明の強化ガラスの切断方法において、前記初期クラックの形成工程では、波長域が２５０～３０００ｎｍ、かつ、パルス幅が１０００ｎｓ以下のパルスレーザ光を用いることが好ましい。 In the method for cutting tempered glass of the present invention, it is preferable to use pulsed laser light having a wavelength range of 250 to 3000 nm and a pulse width of 1000 ns or less in the initial crack forming step.

　本発明の強化ガラスの切断方法において、前記初期クラックの形成工程では、前記強化ガラスの端面よりレーザ光を入射して、前記強化ガラスの前記圧縮応力層よりも内部側にレーザ光を集光させて初期クラックを形成することが好ましい。 In the method for cutting tempered glass of the present invention, in the initial crack forming step, laser light is incident from an end face of the tempered glass, and the laser light is condensed on the inner side of the compressive stress layer of the tempered glass. It is preferable to form an initial crack.

　本発明の強化ガラスの切断方法において、前記初期クラックの形成工程では、少なくとも２つのレーザ光を同時に前記強化ガラスの内部側に集光させて、少なくとも２個所に初期クラックを同時に形成することが好ましい。 In the method for cutting tempered glass of the present invention, in the step of forming the initial crack, it is preferable that at least two laser beams are simultaneously focused on the inner side of the tempered glass and the initial crack is simultaneously formed in at least two places. .

　本発明の強化ガラスの切断方法において、前記強化ガラスの内部加熱にレーザ光の照射を用いることが好ましい。
　また、本発明の強化ガラスの切断方法において、前記強化ガラスの内部加熱に放電を用いることが好ましい。 In the method for cutting tempered glass of the present invention, it is preferable to use laser light irradiation for internal heating of the tempered glass.
Moreover, in the cutting method of the tempered glass of this invention, it is preferable to use discharge for the internal heating of the said tempered glass.

　本発明を用いることで、強化ガラスの切断精度が向上する。 The cutting accuracy of the tempered glass is improved by using the present invention.

図１は、強化ガラスの一構成例を示した模式図である。FIG. 1 is a schematic view showing a configuration example of tempered glass. 図２は、図１の強化ガラス１０における残留応力の厚さ方向（板厚方向）の分布を示した模式図である。FIG. 2 is a schematic diagram showing the distribution of residual stress in the thickness direction (plate thickness direction) in the tempered glass 10 of FIG. 図３は、強化ガラス内部における初期クラックの位置を示した模式図である。FIG. 3 is a schematic diagram showing the position of the initial crack inside the tempered glass. 図４は、平面視した強化ガラスにおける初期クラックの位置を示した模式図である。FIG. 4 is a schematic diagram showing the position of the initial crack in the tempered glass in plan view. 図５は、強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラックの位置が略一致の場合の一例の模式図である。FIG. 5 is a schematic diagram of an example in which the positions of the initial cracks in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10) are substantially the same. 図６は、放電による強化ガラスの内部加熱、および、それによる強化ガラスの切断を示した模式図である。FIG. 6 is a schematic diagram showing internal heating of tempered glass by electric discharge and cutting of tempered glass thereby.

　以下、図面を参照して本発明を説明する。
　図１は、強化ガラスの一構成例を示した模式図である。図１に示すように、強化ガラス１０では、板状ガラス部材の両主表面１１ａ，１１ｂに圧縮応力層１２ａ，１２ｂが形成されている。ここで、圧縮応力層とは、化学処理または熱処理によって、圧縮応力を残留させた層である。 The present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view showing a configuration example of tempered glass. As shown in FIG. 1, in the tempered glass 10, compression stress layers 12a and 12b are formed on both main surfaces 11a and 11b of the plate-like glass member. Here, the compressive stress layer is a layer in which compressive stress remains by chemical treatment or heat treatment.

　図２は、図１の強化ガラス１０における残留応力の厚さ方向（板厚方向）の分布を示した模式図である。図２に示すように、強化ガラス１０の両主表面１１ａ，１１ｂに存在する圧縮応力層１２ａ，１２ｂでは、表面付近に残留する圧縮応力が最も高く、内部に向けて徐々に小さくなる傾向にある。圧縮応力層１２ａ，１２ｂよりも強化ガラスの内部側１３では、圧縮応力に対する反作用として、引張応力が残留している。 FIG. 2 is a schematic diagram showing the distribution of residual stress in the thickness direction (plate thickness direction) in the tempered glass 10 of FIG. As shown in FIG. 2, in the compressive stress layers 12a and 12b existing on both main surfaces 11a and 11b of the tempered glass 10, the compressive stress remaining in the vicinity of the surface is the highest and tends to gradually decrease toward the inside. . On the inner side 13 of the tempered glass than the compressive stress layers 12a and 12b, tensile stress remains as a reaction against the compressive stress.

　圧縮応力層１２ａ，１２ｂにおける最大残留圧縮応力Ｓ１，Ｓ２は、通常の化学強化ガラスの場合、１００～１２００ＭＰａであり、好ましくは、４００～１０００ＭＰａであり、より好ましくは５００～９００ＭＰａである。
　圧縮応力層１２ａ，１２ｂの厚さＤ１，Ｄ２は、通常の化学強化ガラスの場合、５～１００μｍであり、好ましくは、１０～９０μｍであり、より好ましくは２０～８０μｍである。 The maximum residual compressive stresses S1 and S2 in the compressive stress layers 12a and 12b are 100 to 1200 MPa, preferably 400 to 1000 MPa, more preferably 500 to 900 MPa in the case of ordinary chemically strengthened glass.
The thicknesses D1 and D2 of the compressive stress layers 12a and 12b are 5 to 100 μm, preferably 10 to 90 μm, and more preferably 20 to 80 μm in the case of ordinary chemically strengthened glass.

　強化ガラス１０の両主表面に圧縮応力層１２ａ，１２ｂを形成する方法としては、風冷強化法および化学強化法が挙げられる。
　風冷強化法は、強化ガラス１０をなす板状ガラス部材を、軟化点付近の温度に保持した状態で、その両主表面１１ａ，１１ｂを急冷して、両主表面１１ａ，１１ｂと内部側１３との間に温度差をつけることで、圧縮応力層１２ａ，１２ｂを形成する。風冷強化法は、厚さが大きい板状ガラス部材に圧縮応力層を形成するのに好適である。 Examples of a method for forming the compressive stress layers 12a and 12b on both main surfaces of the tempered glass 10 include an air cooling strengthening method and a chemical strengthening method.
In the air-cooled tempering method, both the main surfaces 11a and 11b are rapidly cooled in a state in which the plate-like glass member forming the tempered glass 10 is maintained at a temperature near the softening point, and both the main surfaces 11a and 11b are connected to the inner side 13. The compressive stress layers 12a and 12b are formed by making a temperature difference between the two. The air cooling strengthening method is suitable for forming a compressive stress layer on a sheet glass member having a large thickness.

　化学強化法は、強化ガラス１０をなす板状ガラス部材の両主表面１１ａ，１１ｂをイオン交換し、ガラスに含まれる小さなイオン半径のイオン（例えば、Ｌｉイオン、Ｎａイオン）を、大きなイオン半径のイオン（例えば、Ｋイオン）に置換することで、圧縮応力層１２ａ，１２ｂを形成する。化学強化法は、アルカリ金属元素を含むソーダライムガラスからなる板状ガラス部材に圧縮応力層を形成するのに好適である。 In the chemical strengthening method, both the main surfaces 11a and 11b of the plate-like glass member forming the tempered glass 10 are ion-exchanged, and ions having a small ion radius (for example, Li ions and Na ions) contained in the glass are exchanged with a large ion radius. By substituting with ions (for example, K ions), the compressive stress layers 12a and 12b are formed. The chemical strengthening method is suitable for forming a compressive stress layer on a sheet glass member made of soda lime glass containing an alkali metal element.

　強化ガラス１０をなす板状ガラス部材の厚さは、強化ガラス１０の用途などに応じて適宜設定される。例えば、強化ガラス１０の厚さは、０．１～２．０ｍｍである。化学強化ガラスの場合、厚さが０．１ｍｍ未満になると、板状ガラス部材に化学強化処理を施すことが難しい。一方で、強化ガラス１０の厚さを２．０ｍｍ以下とすることで、強化ガラス１０を十分に薄板化および軽量化することができる。強化ガラス１０の厚さは、好ましくは０．３～１．８ｍｍ、より好ましくは０．５～１．５ｍｍである。 The thickness of the plate-like glass member forming the tempered glass 10 is appropriately set according to the use of the tempered glass 10 or the like. For example, the tempered glass 10 has a thickness of 0.1 to 2.0 mm. In the case of chemically strengthened glass, when the thickness is less than 0.1 mm, it is difficult to perform chemical strengthening treatment on the plate-like glass member. On the other hand, by setting the thickness of the tempered glass 10 to 2.0 mm or less, the tempered glass 10 can be sufficiently reduced in thickness and weight. The thickness of the tempered glass 10 is preferably 0.3 to 1.8 mm, more preferably 0.5 to 1.5 mm.

　強化ガラス１０の組成は、その用途に応じて選定される。例えば、酸化物基準で下記組成の強化ガラスが例示される。
（組成１：モル百分率表示）ＳｉＯ2を５０～７４％、Ａｌ2Ｏ3を１～１０％、Ｎａ2Ｏを６～１４％、Ｋ2Ｏを３～１５％、ＭｇＯを２～１５％、ＣａＯを０～１０％、ＺｒＯ2を０～５％含有し、ＳｉＯ2およびＡｌ2Ｏ3の含有量の合計が７５％以下、Ｎａ2ＯおよびＫ2Ｏの含有量の合計Ｎａ2Ｏ＋Ｋ2Ｏが１２～２５％、ＭｇＯおよびＣａＯの含有量の合計ＭｇＯ＋ＣａＯが７～１５％。
（組成２：モル百分率表示）ＳｉＯ2を６１～６６％、Ａｌ2Ｏ3を６～１２％、ＭｇＯを７～１３％、Ｎａ2Ｏを９～１７％、Ｋ2Ｏを０～７％含有し、ＺｒＯ2を含有する場合その含有量が０．８％以下。
（組成３：質量百分率表示）ＳｉＯ2を７５．５～８５．５％、ＭｇＯを１～８％、ＣａＯを０～７％、Ａｌ2Ｏ3を０～５％、Ｎａ2Ｏを１０～２２．５％を含有し、ＭｇＯの含有量がＣａＯの含有量より多く、ＭｇＯおよびＣａＯの含有量の合計（ＭｇＯ＋ＣａＯ）が８％以下、ＭｇＯ、ＣａＯおよびＮａ2Ｏの含有量の合計が２４．５％以下、ＭｇＯおよびＣａＯの含有量（ＭｇＯ＋ＣａＯ）をＮａ2Ｏの含有量で除して得られた比が０．４５以下。 The composition of the tempered glass 10 is selected according to its application. For example, the tempered glass of the following composition is illustrated on an oxide basis.
(Composition 1: expressed as mole percentage) SiO 2 50-74%, Al 2 O 3 1-10%, Na 2 O 6-14%, K 2 O 3-15%, MgO 2-15% CaO 0-10%, ZrO 2 0-5%, the total content of SiO 2 and Al 2 O 3 is 75% or less, the total content of Na 2 O and K 2 O Na 2 O + K 2 O 12-25%, total MgO and CaO content MgO + CaO 7-15%.
(Composition 2: mole percentage display) SiO 2 61-66%, Al 2 O 3 6-12%, MgO 7-13%, Na 2 O 9-17%, K 2 O 0-7% If it contains ZrO 2 , its content is 0.8% or less.
(Composition 3: In percentage by mass) SiO 2 is 75.5 to 85.5%, MgO is 1 to 8%, CaO is 0 to 7%, Al 2 O 3 is 0 to 5%, Na 2 O is 10 to 22.5%, the content of MgO is greater than the content of CaO, the total content of MgO and CaO (MgO + CaO) is 8% or less, and the total content of MgO, CaO and Na 2 O is 24 The ratio obtained by dividing the MgO and CaO content (MgO + CaO) by the Na 2 O content is 0.45 or less.

　本発明の強化ガラスの切断方法では、強化ガラス１０の圧縮応力層１２ａ，１２ｂよりも内部側（以下、本明細書において強化ガラスの内部側という。）１３に、レンズ等を用いてレーザ光を集光して初期クラックを形成する。
　強化ガラス１０の両主表面１１ａ，１１ｂに存在する圧縮応力層１２ａ，１２ｂにレーザ光を集光して初期クラックを形成すると、初期クラックの形成による構造緩和によってクラックの自走が起こり、クラックが強化ガラスの表面まで達する結果、強化ガラスの表面に割れが生じやすくなる。また、表面に割れが生じない場合でも、初期クラック形成の際にカレットが飛散して強化ガラスの表面に付着するおそれがある。 In the method for cutting tempered glass of the present invention, a laser beam is applied to the inner side (hereinafter referred to as the inner side of the tempered glass in this specification) 13 of the tempered glass 10 from the compressive stress layers 12a and 12b. Concentrate to form initial cracks.
When laser beams are focused on the compressive stress layers 12a and 12b existing on both main surfaces 11a and 11b of the tempered glass 10 to form initial cracks, the cracks are caused to self-run due to structural relaxation due to the formation of initial cracks. As a result of reaching the surface of the tempered glass, the surface of the tempered glass is easily cracked. Even when the surface does not crack, the cullet may scatter and adhere to the surface of the tempered glass when the initial crack is formed.

　強化ガラス１０の内部側１３にレーザ光を集光して初期クラックを形成する際には、強化ガラス１０の平面視での位置が略同一であって、かつ、該強化ガラス１０の厚さ方向における位置が異なる少なくとも２個所に初期クラックを形成する必要がある。
　図３、４は強化ガラス１０における初期クラックの位置を示した模式図であり、図３は、強化ガラス１０を端面側から見た図であり、図４は、強化ガラス１０の主表面１１ａを平面視した図である。
　図３には、強化ガラス１０の内部側１３に、該強化ガラス１０の厚さ方向における位置が異なる２個所に初期クラック２０ａ，２０ｂが形成されている。
　図４では、強化ガラス１０の主表面１１ａの平面視での初期クラック２０ａ，２０ｂの位置が同一になっている。 When the laser beam is focused on the inner side 13 of the tempered glass 10 to form an initial crack, the position of the tempered glass 10 in the plan view is substantially the same, and the thickness direction of the tempered glass 10 It is necessary to form initial cracks in at least two places having different positions.
3 and 4 are schematic views showing the positions of the initial cracks in the tempered glass 10, FIG. 3 is a view of the tempered glass 10 as viewed from the end face side, and FIG. 4 shows the main surface 11a of the tempered glass 10. FIG.
In FIG. 3, initial cracks 20 a and 20 b are formed on the inner side 13 of the tempered glass 10 at two different positions in the thickness direction of the tempered glass 10.
In FIG. 4, the positions of the initial cracks 20a and 20b in plan view of the main surface 11a of the tempered glass 10 are the same.

　本発明の強化ガラスの切断方法において、強化ガラス１０の内部側１３に、該強化ガラス１０の厚さ方向における位置が異なる少なくとも２個所に初期クラックを形成する理由は以下の通りである。
　上述したように、強化ガラス１０の圧縮応力層１２ａ，１２ｂに初期クラックを形成すると、初期クラックの形成による構造緩和によってクラックの自走が起こり、強化ガラスの表面に割れが生じるおそれがある。これに対し、強化ガラス１０の内部側１３に初期クラックを形成した場合、初期クラックの形成による構造緩和がきわめて小さいため、クラックの自走は起こらず、強化ガラスの割れを生じることはない。
　しかしながら、強化ガラス１０の内部側１３に初期クラックを１個所のみ形成した場合、初期クラックの形成に続いて実施する内部加熱によって強化ガラス１０を切断する際に、以下の理由により、強化ガラス１０に欠けが生じるおそれがある。
　強化ガラス１０の内部側１３に初期クラックを１個所のみ形成する場合、強化ガラス１０の厚さ方向における初期クラックの長さが短くなるため、初期クラックの形成に続いて実施する内部加熱によって強化ガラス１０を切断するためには、該強化ガラス１０の表面側、すなわち、圧縮応力層１２ａ，１２ｂに近い位置に初期クラックを形成する必要がある。
　また、強化ガラス１０の内部側１３に初期クラックを１個所のみ形成した場合、強化ガラス１０の厚さ方向における初期クラックの長さが短いため、強化ガラス１０を端面側からみた場合の初期クラックの断面積と、強化ガラス１０の主表面１１ａの平面視での初期クラックの断面積と、の間に有意な差がない状態となる。
　この結果、強化ガラス１０を内部加熱した際に、該強化ガラス１０の厚さ方向にクラックが進展せずに、該強化ガラス１０の表面方向（主表面１１ａ，１１ｂ方向）にクラックが進展し、強化ガラス１０に欠けが生じるおそれがある。
　これに対し、強化ガラス１０の内部側１３に対して、強化ガラス１０の厚さ方向における位置が異なる少なくとも２個所に初期クラックを形成した場合、強化ガラス１０の厚さ方向における初期クラックの合計長さが長くなるため、強化ガラス１０を端面側からみた場合の初期クラックの断面積が、強化ガラス１０の主表面１１ａの平面視での初期クラックの断面積よりも大きくなる。
　この結果、強化ガラス１０を内部加熱した際に、該強化ガラス１０の厚さ方向にクラックが進展するため、強化ガラス１０の切断精度に優れている。 In the method for cutting tempered glass of the present invention, the reason why initial cracks are formed on the inner side 13 of the tempered glass 10 in at least two places where the positions in the thickness direction of the tempered glass 10 are different is as follows.
As described above, when initial cracks are formed in the compressive stress layers 12a and 12b of the tempered glass 10, the cracks are free-running due to structural relaxation due to the formation of the initial cracks, and the surface of the tempered glass may be cracked. On the other hand, when an initial crack is formed on the inner side 13 of the tempered glass 10, the structural relaxation due to the formation of the initial crack is extremely small, so that the cracks are not self-propelled and the tempered glass is not cracked.
However, when only one initial crack is formed on the inner side 13 of the tempered glass 10, when the tempered glass 10 is cut by internal heating performed subsequent to the formation of the initial crack, the tempered glass 10 has the following reasons. Chipping may occur.
When only one initial crack is formed on the inner side 13 of the tempered glass 10, the length of the initial crack in the thickness direction of the tempered glass 10 is shortened. Therefore, the tempered glass is formed by internal heating performed after the formation of the initial crack. In order to cut 10, it is necessary to form an initial crack on the surface side of the tempered glass 10, that is, at a position close to the compressive stress layers 12 a and 12 b.
Further, when only one initial crack is formed on the inner side 13 of the tempered glass 10, the length of the initial crack in the thickness direction of the tempered glass 10 is short, so that the initial crack when the tempered glass 10 is viewed from the end surface side is reduced. There is no significant difference between the cross-sectional area and the cross-sectional area of the initial crack in the plan view of the main surface 11a of the tempered glass 10.
As a result, when the tempered glass 10 is internally heated, cracks develop in the surface direction of the tempered glass 10 (main surface 11a, 11b direction) without progressing in the thickness direction of the tempered glass 10, There is a risk of chipping in the tempered glass 10.
On the other hand, when the initial crack is formed in at least two places where the positions in the thickness direction of the tempered glass 10 are different from the inner side 13 of the tempered glass 10, the total length of the initial cracks in the thickness direction of the tempered glass 10 Therefore, the cross-sectional area of the initial crack when the tempered glass 10 is viewed from the end surface side is larger than the cross-sectional area of the initial crack in the plan view of the main surface 11a of the tempered glass 10.
As a result, when the tempered glass 10 is internally heated, cracks progress in the thickness direction of the tempered glass 10, so that the cutting accuracy of the tempered glass 10 is excellent.

　なお、図３では、強化ガラス１０の内部側１３の上端付近と下端付近に初期クラック２０ａ，２０ｂが形成されているが、初期クラックを形成する位置はこれに限定されない。
　初期クラックを形成する位置は、強化ガラス１０の内部側１３であって、かつ、初期クラック同士の強化ガラス１０の厚さ方向における位置が互いに異なる位置であればよい。したがって、初期クラックは全て強化ガラス１０の内部側１３の上端に近い位置に形成されていたり、下端に近い位置に形成されていたり、中央付近に形成されていてもよい。また、初期クラックは強化ガラス１０の内部側１３の上端に近い位置と中央付近に形成されていたり、下端に近い位置と中央付近に形成されていてもよい。
　強化ガラス１０に初期クラックを３個所以上形成する場合は、強化ガラス１０の内部側１３の上端に近い位置と、中央付近と、下端に近い位置に形成してもよい。
　強化ガラス１０の内部側１３の上端に近い位置や、下端に近い位置に初期クラックを形成する場合、クラックの一部が圧縮応力層１２ａ，１２ｂにかかっていてもよい。
　図２に示したように、圧縮応力層１２ａ，１２ｂに残留する圧縮応力は、強化ガラス１０の内部側１３に近い位置ではきわめて小さくなるので、強化ガラス１０の内部側１３の上端に近い位置や、下端に近い位置に形成した初期クラックの一部が圧縮応力層１２ａ，１２ｂにかかったとしても、それによる影響は無視できると考えられる。 In FIG. 3, the initial cracks 20 a and 20 b are formed near the upper end and the lower end of the inner side 13 of the tempered glass 10, but the position where the initial crack is formed is not limited to this.
The position where the initial crack is formed may be the inner side 13 of the tempered glass 10 and the position where the initial cracks in the thickness direction of the tempered glass 10 are different from each other. Therefore, all of the initial cracks may be formed at a position near the upper end of the inner side 13 of the tempered glass 10, may be formed at a position near the lower end, or may be formed near the center. In addition, the initial crack may be formed near the upper end and near the center of the inner side 13 of the tempered glass 10, or may be formed near the lower end and near the center.
When three or more initial cracks are formed in the tempered glass 10, the cracks may be formed at a position near the upper end of the inner side 13 of the tempered glass 10, near the center, and near the lower end.
When an initial crack is formed at a position near the upper end of the inner side 13 of the tempered glass 10 or a position near the lower end, a part of the crack may be applied to the compressive stress layers 12a and 12b.
As shown in FIG. 2, the compressive stress remaining in the compressive stress layers 12 a and 12 b is extremely small at a position close to the inner side 13 of the tempered glass 10. Even if a part of the initial crack formed at a position close to the lower end is applied to the compressive stress layers 12a and 12b, it is considered that the influence of the crack can be ignored.

　強化ガラス１０の内部側１３に形成する初期クラックは、強化ガラス１０の厚さ方向における位置が互いに近くてもよい。また、強化ガラス１０の内部側１３に形成した初期クラック同士が連結し、一見したところ単一の初期クラックに見える状態になった場合でも本発明の趣旨を逸脱するものではない。 The initial cracks formed on the inner side 13 of the tempered glass 10 may be close to each other in the thickness direction of the tempered glass 10. Further, even if the initial cracks formed on the inner side 13 of the tempered glass 10 are connected to each other and seemingly appear as a single initial crack, it does not depart from the spirit of the present invention.

　強化ガラス１０の内部側１３に形成する初期クラックは、内部加熱による強化ガラス１０の切断の起点となることから、強化ガラス１０の厚さ方向における初期クラックの長さ、より具体的には、強化ガラス１０の厚さ方向における初期クラックの合計長さが長いほど、強化ガラス１０の切断精度が向上すると考えられる。但し、強化ガラス１０の厚さに対して、初期クラックの合計長さが長すぎると、初期クラックが強化ガラス１０の表面（主面１１ａ，１１ｂ）の近くまで達するので、強化ガラス１０の表面に割れが生じるおそれがある。一方、強化ガラス１０の厚さに対して、初期クラックの合計長さが短すぎると、初期クラックの形成に続いて実施する内部加熱によって、強化ガラス１０の切断の開始となるクラックの進展が開始しなかったり、クラックの進展が開始した場合でも、以下の理由により、強化ガラス１０に欠けが生じるおそれがある。 Since the initial crack formed on the inner side 13 of the tempered glass 10 serves as a starting point for cutting the tempered glass 10 by internal heating, the length of the initial crack in the thickness direction of the tempered glass 10, more specifically, It is considered that the cutting accuracy of the tempered glass 10 is improved as the total length of the initial cracks in the thickness direction of the glass 10 is longer. However, if the total length of the initial cracks is too long with respect to the thickness of the tempered glass 10, the initial cracks reach close to the surface of the tempered glass 10 (main surfaces 11a, 11b). There is a risk of cracking. On the other hand, if the total length of the initial cracks is too short with respect to the thickness of the tempered glass 10, progress of cracks that start cutting of the tempered glass 10 is started by internal heating performed following the formation of the initial cracks. Even when cracks start to progress, the tempered glass 10 may be chipped for the following reasons.

　本発明の強化ガラスの切断方法において、強化ガラス１０の厚さをｔ（ｍｍ）とするとき、強化ガラス１０の厚さ方向における初期クラックの合計長さを０．２ｔ～０．８ｔとする。
　強化ガラス１０の内部側１３に形成する初期クラックの合計長さが０．２ｔより短い場合、初期クラックの形成に続いて実施する内部加熱によって、強化ガラス１０の切断の開始となるクラックの進展が開始しなかったり、クラックの進展が開始した場合でも、以下の理由により、強化ガラス１０に欠けが生じるおそれがある。 In the method for cutting tempered glass of the present invention, when the thickness of the tempered glass 10 is t (mm), the total length of initial cracks in the thickness direction of the tempered glass 10 is 0.2 t to 0.8 t.
When the total length of the initial cracks formed on the inner side 13 of the tempered glass 10 is shorter than 0.2 t, the internal heating performed following the formation of the initial cracks causes the cracks to start cutting the tempered glass 10. Even if it does not start or the progress of cracks starts, the tempered glass 10 may be chipped for the following reason.

　強化ガラス１０の内部側１３に形成する初期クラックの合計長さが０．２ｔよりも短い場合、強化ガラス１０の厚さ方向における初期クラックの合計長さが短いため、初期クラックの形成に続いて実施する内部加熱によって強化ガラス１０を切断するためには、該強化ガラス１０の表面側、すなわち、圧縮応力層１２ａ，１２ｂに近い位置に初期クラックを形成する必要がある。
　また、強化ガラス１０の内部側１３に形成する初期クラックの合計長さが０．２ｔよりも短い場合、強化ガラス１０の厚さ方向における初期クラックの合計長さが短いため、強化ガラス１０を端面側からみた場合の初期クラックの断面積と、強化ガラス１０の主表面１１ａの平面視での初期クラックの断面積と、の間に有意な差がない状態となる。
　この結果、強化ガラス１０を内部加熱した際に、該強化ガラス１０の厚さ方向にクラックが進展せずに、該強化ガラス１０の表面方向（主表面１１ａ，１１ｂ方向）にクラックが進展し、強化ガラス１０に欠けが生じるおそれがある。 When the total length of initial cracks formed on the inner side 13 of the tempered glass 10 is shorter than 0.2 t, the total length of initial cracks in the thickness direction of the tempered glass 10 is short. In order to cut the tempered glass 10 by internal heating, it is necessary to form an initial crack on the surface side of the tempered glass 10, that is, at a position close to the compressive stress layers 12a and 12b.
Further, when the total length of the initial cracks formed on the inner side 13 of the tempered glass 10 is shorter than 0.2 t, the total length of the initial cracks in the thickness direction of the tempered glass 10 is short. There is no significant difference between the cross-sectional area of the initial crack when viewed from the side and the cross-sectional area of the initial crack in plan view of the main surface 11a of the tempered glass 10.
As a result, when the tempered glass 10 is internally heated, cracks develop in the surface direction of the tempered glass 10 (main surface 11a, 11b direction) without progressing in the thickness direction of the tempered glass 10, There is a risk of chipping in the tempered glass 10.

　これに対し、強化ガラス１０の内部側１３に形成する初期クラックの合計長さを０．２ｔ以上にした場合、強化ガラス１０を端面側からみた場合の初期クラックの断面積が、強化ガラス１０の主表面１１ａの平面視での初期クラックの断面積よりも大きくなる。
　この結果、強化ガラス１０を内部加熱した際に、該強化ガラス１０の厚さ方向にクラックが進展するため、強化ガラス１０の切断精度に優れている。 On the other hand, when the total length of the initial cracks formed on the inner side 13 of the tempered glass 10 is 0.2 t or more, the cross-sectional area of the initial cracks when the tempered glass 10 is viewed from the end face side is The cross-sectional area of the initial crack in plan view of the main surface 11a is larger.
As a result, when the tempered glass 10 is internally heated, cracks progress in the thickness direction of the tempered glass 10, so that the cutting accuracy of the tempered glass 10 is excellent.

　一方、強化ガラス１０の内部側１３に形成する初期クラックの合計長さが０．８ｔより長くなると、初期クラックが強化ガラス１０の表面（主面１１ａ，１１ｂ）の近くまで達し、強化ガラス１０の表面に割れが生じるおそれがあるので、初期クラックの合計長さは０．８ｔ以下にする必要がある。
　強化ガラス１０の内部側１３に形成する初期クラックの合計長さは、０．２５ｔ～０．７５ｔであることが好ましく、０．３ｔ～０．７ｔであることがより好ましい。 On the other hand, when the total length of the initial cracks formed on the inner side 13 of the tempered glass 10 is longer than 0.8 t, the initial crack reaches near the surface (main surfaces 11a, 11b) of the tempered glass 10, and Since there is a risk of cracking on the surface, the total length of the initial cracks needs to be 0.8 t or less.
The total length of the initial cracks formed on the inner side 13 of the tempered glass 10 is preferably 0.25 t to 0.75 t, and more preferably 0.3 t to 0.7 t.

　本発明の強化ガラスの切断方法において、強化ガラス１０の内部側１３に形成する初期クラックは、図４に示すように、強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラック２０ａ，２０ｂの位置が同一であることが必要となる。強化ガラス１０の内部側１３に初期クラックを形成するのは、続いて実施する内部加熱による強化ガラスの切断の際に、切断の起点とするためである。このため、強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラックの位置にずれがあると、切断精度が低下するおそれがある。 In the method for cutting tempered glass of the present invention, the initial cracks formed on the inner side 13 of the tempered glass 10 are as seen in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10), as shown in FIG. It is necessary that the initial cracks 20a and 20b have the same position. The reason why the initial crack is formed on the inner side 13 of the tempered glass 10 is that it is used as a starting point of cutting when the tempered glass is subsequently cut by internal heating. For this reason, if there is a shift in the position of the initial crack in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10), the cutting accuracy may be lowered.

　但し、本発明の強化ガラスの切断方法では、レーザ光を集光して初期クラックを形成するため、初期クラックが形成される位置を正確に制御することが困難な場合もある。このため、強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラックの位置を完全に一致させることが困難な場合もある。
　強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラックの位置は、続いて実施する内部加熱による強化ガラスの切断精度に悪影響をおよぼさない限り、完全一致である必要はなく、略一致であればよい。 However, in the method for cutting tempered glass of the present invention, since the initial crack is formed by condensing the laser beam, it may be difficult to accurately control the position where the initial crack is formed. For this reason, it may be difficult to completely match the positions of the initial cracks in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10).
The position of the initial crack in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10) is in perfect agreement as long as the cutting accuracy of the tempered glass by subsequent internal heating is not adversely affected. It does not have to be, and it is sufficient if it is substantially the same.

　図５は、強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラックの位置が略一致の場合の一例の模式図である。
　図５では、初期クラック２０ａ、２０ｂが、切断予定線３０に沿って若干ずれた位置に存在している。ここで、初期クラック２０ａ、２０ｂの中心間を結ぶ線は、切断予定線３０上に存在しており、両者の方向は一致している。初期クラック２０ａ、２０ｂがこのような位置関係であれば、内部加熱による強化ガラスの切断精度に悪影響をおよぼすことはない。
　上述したように、本発明の強化ガラスの切断方法では、レーザ光を集光して初期クラックを形成するため、初期クラックが形成される位置を正確に制御することが困難な場合もある。図５では、初期クラック２０ａ、２０ｂの中心が切断予定線３０上に存在しているが、レーザ光を集光して初期クラックを形成するため、初期クラックの中心が切断予定線上に存在しない場合もある。しかしながら、このような場合であっても、初期クラックの少なくとも一部は、切断予定線上に存在する必要がある。
　また、初期クラック同士の位置がずれている場合でも、両者の少なくとも一部がかさなっている必要がある。 FIG. 5 is a schematic diagram of an example in which the positions of the initial cracks in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10) are substantially the same.
In FIG. 5, the initial cracks 20 a and 20 b are present at positions slightly shifted along the planned cutting line 30. Here, a line connecting the centers of the initial cracks 20a and 20b exists on the planned cutting line 30, and the directions of both coincide with each other. If the initial cracks 20a and 20b are in such a positional relationship, the cutting accuracy of the tempered glass due to internal heating will not be adversely affected.
As described above, in the method for cutting tempered glass of the present invention, since the initial crack is formed by condensing the laser beam, it may be difficult to accurately control the position where the initial crack is formed. In FIG. 5, the centers of the initial cracks 20 a and 20 b exist on the planned cutting line 30, but the laser beam is condensed to form the initial crack, and therefore the initial crack center does not exist on the planned cutting line. There is also. However, even in such a case, at least a part of the initial crack needs to exist on the planned cutting line.
Even when the positions of the initial cracks are deviated, at least a part of both needs to be covered.

　強化ガラス１０の内部側１３に形成する初期クラックは、内部加熱による強化ガラス１０の切断の起点となることから、強化ガラス１０の切断予定線３０の始点に近い位置に形成することが好ましい。図示した態様は、強化ガラスを完全に切断（フルカット加工）する場合を想定しているので、切断予定線３０の始点は強化ガラス１０の端部である。
　このため、強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラックの位置は、該強化ガラス１０の端部から５ｍｍ以内の位置であることが好ましい。
　但し、強化ガラス１０の切断予定線３０の始点に近い位置に形成すると、初期クラックの位置が強化ガラス１０の端部に近づくため、形成された初期クラック１０が強化ガラス１０の端面に達し、強化ガラス１０に割れを生じるおそれがある。
　このため、強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラックの位置は、該強化ガラス１０の端部から０．２ｍｍ以上離れていることが好ましい。
　なお、図示した態様は、強化ガラス１０を完全に切断（フルカット加工）する場合を想定しているため、切断予定線３０の始点が強化ガラス１０の端部となるが、強化ガラス１０の一部を切断する場合、切断予定線３０の始点が強化ガラス１０の端部以外となる場合もある。このような場合、強化ガラス１０の平面視（強化ガラス１０の主表面１１ａの平面視）での初期クラックの位置は、切断予定線３０の始点から５ｍｍ以内の位置であることが好ましい。 Since the initial crack formed on the inner side 13 of the tempered glass 10 serves as a starting point for cutting the tempered glass 10 by internal heating, it is preferably formed at a position close to the starting point of the planned cutting line 30 of the tempered glass 10. Since the illustrated mode assumes a case where the tempered glass is completely cut (full cut processing), the starting point of the planned cutting line 30 is the end of the tempered glass 10.
For this reason, the position of the initial crack in a plan view of the tempered glass 10 (a plan view of the main surface 11 a of the tempered glass 10) is preferably a position within 5 mm from the end of the tempered glass 10.
However, since the position of the initial crack approaches the end of the tempered glass 10 when it is formed at a position close to the starting point of the planned cutting line 30 of the tempered glass 10, the formed initial crack 10 reaches the end surface of the tempered glass 10 and is strengthened. There is a possibility that the glass 10 is cracked.
For this reason, the position of the initial crack in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10) is preferably separated from the end of the tempered glass 10 by 0.2 mm or more.
In addition, since the illustrated aspect assumes the case where the tempered glass 10 is completely cut (full cut processing), the starting point of the planned cutting line 30 is the end of the tempered glass 10. When the part is cut, the starting point of the planned cutting line 30 may be other than the end of the tempered glass 10. In such a case, the position of the initial crack in a plan view of the tempered glass 10 (a plan view of the main surface 11a of the tempered glass 10) is preferably a position within 5 mm from the starting point of the planned cutting line 30.

　本発明の強化ガラスの切断方法では、レーザ光を集光して、強化ガラス１０の内部側１３に初期クラックを形成するために、波長域が２５０～３０００ｎｍ、かつ、ピークパワー密度が１×１０12～１×１０16Ｗ／ｍ2のパルスレーザ光を用いることが好ましい。 In the method for cutting tempered glass of the present invention, in order to focus laser light and form an initial crack on the inner side 13 of the tempered glass 10, the wavelength range is 250 to 3000 nm and the peak power density is 1 × 10. It is preferable to use a pulse laser beam of 12 to 1 × 10 16 W / m 2 .

　波長域が２５０～３０００ｎｍのレーザ光は、上述した組成の強化ガラスをある程度透過するため、レーザ光のパワー密度が低い場合、レーザ光を集光しても、強化ガラス１０の内部側１３に初期クラックが形成されることはない。しかしながら、パワー密度を高めていき、ある閾値を超えるとレーザ光の非線形吸収が起こるようになる。
　本発明の強化ガラスの切断方法では、レーザ光の非線形吸収を利用して、強化ガラス１０の内部側１３に初期クラックを形成する。
　ピークパワー密度が１×１０12～１×１０16Ｗ／ｍ2のパルスレーザ光であれば、波長域が２５０～３０００ｎｍのレーザ光の非線形吸収が起こるので、強化ガラス１０の内部側１３に初期クラックを形成することができる。
　ピークパワー密度が１×１０12Ｗ／ｍ2未満だと、波長域が２５０～３０００ｎｍのレーザ光の非線形吸収により、強化ガラス１０の内部側１３に初期クラックを形成することができない。
　一方、ピークパワー密度が１×１０16Ｗ／ｍ2超だと、レーザ光を集光した際に、強化ガラス１０に割れが生じるおそれがある。
　パルスレーザ光のピークパワー密度は、１×１０13～１×１０15Ｗ／ｍ2であることが好ましい。 Laser light having a wavelength range of 250 to 3000 nm is transmitted through the tempered glass having the above-described composition to some extent. Therefore, when the power density of the laser light is low, the laser beam is focused on the inner side 13 of the tempered glass 10 at the initial stage. No cracks are formed. However, when the power density is increased and a certain threshold value is exceeded, nonlinear absorption of the laser light occurs.
In the method for cutting tempered glass of the present invention, initial cracks are formed on the inner side 13 of the tempered glass 10 by utilizing nonlinear absorption of laser light.
In the case of pulsed laser light having a peak power density of 1 × 10 12 to 1 × 10 16 W / m 2 , nonlinear absorption of laser light having a wavelength region of 250 to 3000 nm occurs. Cracks can be formed.
When the peak power density is less than 1 × 10 12 W / m 2 , initial cracks cannot be formed on the inner side 13 of the tempered glass 10 due to nonlinear absorption of laser light having a wavelength range of 250 to 3000 nm.
On the other hand, if the peak power density is more than 1 × 10 16 W / m 2 , the tempered glass 10 may be cracked when the laser light is collected.
The peak power density of the pulsed laser beam is preferably 1 × 10 13 to 1 × 10 15 W / m 2 .

　なお、本発明の強化ガラスの切断方法において、上述した組成の強化ガラスをある程度透過する波長域のレーザ光を使用するのは、強化ガラスに吸収される波長域のレーザ光を使用すると、強化ガラスの表面に存在する圧縮応力層でレーザ光が吸収されてしまい、強化ガラスの内部側にレーザ光を集光することができず、強化ガラスの内部側に初期クラックを形成できないためである。
　上述する組成の強化ガラスをある程度透過する波長域のレーザ光としては、波長域が３００～２０００ｎｍのレーザ光を使用することがより好ましく、波長域が３５０～１５００ｎｍのレーザ光を使用することがさらに好ましい。 In the method for cutting tempered glass according to the present invention, the laser beam having a wavelength range that passes through the tempered glass having the above-described composition to some extent is used when the laser beam having a wavelength range absorbed by the tempered glass is used. This is because the laser light is absorbed by the compressive stress layer existing on the surface of the tempered glass, the laser light cannot be condensed on the inner side of the tempered glass, and initial cracks cannot be formed on the inner side of the tempered glass.
As the laser beam having a wavelength range that transmits the tempered glass having the above-described composition to some extent, it is more preferable to use a laser beam having a wavelength range of 300 to 2000 nm, and it is further preferable to use a laser beam having a wavelength range of 350 to 1500 nm. preferable.

　また、上記と同様の理由から、本発明の強化ガラスの切断方法では、レーザ光を集光して、強化ガラス１０の内部側１３に初期クラックを形成するために、波長域が２５０～３０００ｎｍ、かつ、パルス幅が１０００ｎｓ以下のパルスレーザ光を用いることが好ましい。
　パルス幅が１０００ｎｓ以下のパルスレーザ光であれば、波長域が２５０～３０００ｎｍのレーザ光の非線形吸収が起こるので、強化ガラス１０の内部側１３に初期クラックを形成することができる。
　パルスレーザ光のパルス幅は５００ｎｓ以下であることがより好ましく、２００ｎｓ以下であることがさらに好ましい。 For the same reason as described above, in the method for cutting tempered glass of the present invention, the wavelength range is 250 to 3000 nm in order to focus the laser beam and form an initial crack on the inner side 13 of the tempered glass 10. In addition, it is preferable to use pulsed laser light having a pulse width of 1000 ns or less.
If the pulse laser light has a pulse width of 1000 ns or less, nonlinear absorption of laser light having a wavelength region of 250 to 3000 nm occurs, so that an initial crack can be formed on the inner side 13 of the tempered glass 10.
The pulse width of the pulse laser beam is more preferably 500 ns or less, and further preferably 200 ns or less.

　但し、本発明の強化ガラスの切断方法では、強化ガラスの内部側にレーザ光を集光して初期クラックを形成するため、強化ガラスの端面よりレーザ光を入射して、強化ガラスの内部側にレーザ光を集光させてもよい。
　強化ガラスの端面よりレーザ光を入射することにより、少なくとも２つのレーザ光を強化ガラスの内部側に同時に集光させて、少なくとも２個所に初期クラックを同時に形成することができる。 However, in the method for cutting tempered glass of the present invention, the laser beam is focused on the inner side of the tempered glass to form initial cracks. Laser light may be condensed.
By making laser light incident from the end face of the tempered glass, at least two laser lights can be simultaneously focused on the inner side of the tempered glass, and initial cracks can be simultaneously formed in at least two places.

　本発明の強化ガラスの切断方法では、上記の手順で強化ガラス１０の内部側１３に初期クラックを形成した後、強化ガラスを内部加熱することにより、該強化ガラスを切断する。より具体的には、強化ガラスの内部加熱される部位を切断予定線に沿って移動させることによって、該強化ガラスを切断する。
　強化ガラスを内部加熱する方法としては、以下に述べるように、放電を用いる方法、あるいは、レーザ光を照射する方法が好ましく用いられる。 In the method for cutting tempered glass according to the present invention, after the initial crack is formed on the inner side 13 of the tempered glass 10 by the above-described procedure, the tempered glass is internally heated to cut the tempered glass. More specifically, the tempered glass is cut by moving a portion of the tempered glass that is heated inside along a planned cutting line.
As a method for internally heating the tempered glass, a method using discharge or a method of irradiating laser light is preferably used as described below.

　図６は、放電による強化ガラスの内部加熱、および、それによる強化ガラスの切断を示した模式図である。
　図６において、放電電極１００および対向電極２００が所定の間隔を開けて離隔されている。切断対象である強化ガラス１０は、放電電極１００と、対向電極２００と、の間に配置されている。放電電極１００および対向電極２００は交流電源３００に接続されている。但し、対向電極２００はなくてもよい。
　交流電源３００から高周波交流電流を印加すると、放電電極１００と、該放電電極１００と対向する強化ガラス１０の主表面１１ａと、の間に放電４００が形成される。対向電極２００を使用している場合には、対向電極２００と、該対向電極２００と対向する強化ガラス１０の主表面１１ｂと、の間にも放電が形成される。放電電極１００は強化ガラス１０の切断予定線３０の上方に位置しており、切断予定線３０に沿って矢印方向に移動する。但し、ここで言う移動とは、放電電極１００と強化ガラス１０との相対的な移動であり、放電電極１００ではなく強化ガラス１０が矢印と反対方向に移動したのでもよい。
　なお、内部加熱による強化ガラスの切断の開始時においては、放電電極１００は強化ガラス１０の内部側に形成された初期クラック（図示せず）の上方に位置する。 FIG. 6 is a schematic diagram showing internal heating of tempered glass by electric discharge and cutting of tempered glass thereby.
In FIG. 6, the discharge electrode 100 and the counter electrode 200 are separated by a predetermined interval. The tempered glass 10 to be cut is disposed between the discharge electrode 100 and the counter electrode 200. The discharge electrode 100 and the counter electrode 200 are connected to an AC power source 300. However, the counter electrode 200 may not be provided.
When a high frequency alternating current is applied from the alternating current power source 300, a discharge 400 is formed between the discharge electrode 100 and the main surface 11a of the tempered glass 10 facing the discharge electrode 100. When the counter electrode 200 is used, a discharge is also formed between the counter electrode 200 and the main surface 11 b of the tempered glass 10 facing the counter electrode 200. The discharge electrode 100 is located above the planned cutting line 30 of the tempered glass 10 and moves in the direction of the arrow along the planned cutting line 30. However, the movement referred to here is a relative movement between the discharge electrode 100 and the tempered glass 10, and the tempered glass 10 instead of the discharge electrode 100 may move in the direction opposite to the arrow.
In addition, at the time of the start of the cutting | disconnection of the tempered glass by internal heating, the discharge electrode 100 is located above the initial stage crack (not shown) formed in the inner side of the tempered glass 10. FIG.

　強化ガラス１０の放電４００が形成された部位、すなわち、放電電極１００の直下の部位は、放電によって内部加熱されて、その温度が周囲に比べて高温になるので、熱膨張により圧縮応力（熱応力）が作用する。その反作用として、放電電極１００の移動方向後方では、切断予定線３０と直交する方向に引張応力が作用し、強化ガラス１０にクラック４０が形成される。放電電極１００は強化ガラス１０の切断予定線３０に沿って矢印方向に移動させると、強化ガラス１０の内部加熱される部位も切断予定線３０に沿って移動し、クラック４０が強化ガラス１０の長手方向全体にわたって進展し、強化ガラス１０が切断される。 The portion of the tempered glass 10 where the discharge 400 is formed, that is, the portion immediately below the discharge electrode 100 is internally heated by the discharge, and its temperature becomes higher than that of the surroundings. ) Acts. As the reaction, a tensile stress acts in a direction perpendicular to the planned cutting line 30 behind the discharge electrode 100 in the moving direction, and a crack 40 is formed in the tempered glass 10. When the discharge electrode 100 is moved in the direction of the arrow along the planned cutting line 30 of the tempered glass 10, the portion of the tempered glass 10 that is internally heated also moves along the planned cutting line 30, and the crack 40 is the longitudinal length of the tempered glass 10. Progressing over the entire direction, the tempered glass 10 is cut.

　図６に示した構成において、放電電極１００および対向電極２００としては、導電性に優れ、高融点であり、酸化されにくい材料であることが好ましい。このような材料の具体例としては、金、白金、パラジウムのような貴金属もしくはその合金が挙げられ、特に白金もしくはパラジウム、またはそれらの合金が好ましい。 In the configuration shown in FIG. 6, the discharge electrode 100 and the counter electrode 200 are preferably materials that are excellent in conductivity, have a high melting point, and are not easily oxidized. Specific examples of such materials include noble metals such as gold, platinum and palladium or alloys thereof, and platinum or palladium or alloys thereof are particularly preferable.

　放電電極１００と、強化ガラス１０の主表面１１ａと、の間隔は、放電電極１００と強化ガラス１０の主表面１１ａとの間に放電４００を形成することができる限り特に限定されないが、０ｍｍ～１０ｃｍであることが好ましく、０ｍｍ～１０ｍｍであることがより好ましく、０．０５ｍｍ～５ｍｍであることがさらに好ましい。ここで、０ｍｍとは、放電電極１００と強化ガラス１０の主表面１１ａとが接触している状態を意味する。
　対向電極２００と、強化ガラス１０の主表面１１ｂと、の間隔についても上記と同様である。 The distance between the discharge electrode 100 and the main surface 11a of the tempered glass 10 is not particularly limited as long as the discharge 400 can be formed between the discharge electrode 100 and the main surface 11a of the tempered glass 10, but 0 mm to 10 cm. It is preferably 0 mm to 10 mm, more preferably 0.05 mm to 5 mm. Here, 0 mm means a state in which the discharge electrode 100 and the main surface 11a of the tempered glass 10 are in contact.
The distance between the counter electrode 200 and the main surface 11b of the tempered glass 10 is the same as described above.

　交流電源３００は、放電４００を形成可能な高周波の交流電流を発生できる限り特に限定されない。具体例としては、たとえば、テスラ変圧器、フライバック変圧器、高出力高周波発生器、高周波半導体チョッパのような共振変圧器を用いた高周波交流電源が挙げられる。
　交流電源３００は、電圧が１０Ｖ～１０7Ｖ、より好ましくは１００Ｖ～１０6Ｖ、さらに好ましくは１００Ｖ～１０5Ｖで、周波数が１ｋＨｚ～１０ＧＨｚ、より好ましくは１０ｋＨｚ～１ＧＨｚ、さらに好ましくは１００ｋＨｚ～１００ＭＨｚの高周波交流電流を発生することが好ましい。 The AC power supply 300 is not particularly limited as long as it can generate a high-frequency AC current that can form the discharge 400. Specific examples include a high-frequency AC power source using a resonant transformer such as a Tesla transformer, a flyback transformer, a high-output high-frequency generator, and a high-frequency semiconductor chopper.
The AC power supply 300 has a voltage of 10 V to 10 7 V, more preferably 100 V to 10 6 V, still more preferably 100 V to 10 5 V, and a frequency of 1 kHz to 10 GHz, more preferably 10 kHz to 1 GHz, still more preferably 100 kHz to It is preferable to generate a high frequency alternating current of 100 MHz.

　なお、放電４００を形成するため、放電電極１００および対向電極２００、および、両者の間に位置する強化ガラス１０は、圧力１Ｐａ～１００ＭＰａ、より好ましくは１ｋＰａ～１ＭＰａの、窒素雰囲気、アルゴン雰囲気または六フッ化硫黄雰囲気下に置くことが好ましい。 In order to form the discharge 400, the discharge electrode 100, the counter electrode 200, and the tempered glass 10 positioned between them are in a nitrogen atmosphere, an argon atmosphere or six at a pressure of 1 Pa to 100 MPa, more preferably 1 kPa to 1 MPa. It is preferable to place under a sulfur fluoride atmosphere.

　図６に示した構成において、強化ガラス１０の放電４００が形成された部位、すなわち、放電電極１００の直下の部位よりも、切断予定線３０に沿った後方で、強化ガラス１０を冷却してもよい。強化ガラス１０を冷却することによって、強化ガラス１０の内部加熱による熱応力の反作用としての引張応力の作用が促進される。
　ここで、強化ガラス１０を冷却する方法としては、強化ガラス１０の主表面１１ａに気体、液体、エアロゾル等の冷却剤を吹き付ける方法が挙げられる。 In the configuration shown in FIG. 6, even if the tempered glass 10 is cooled behind the part along the planned cutting line 30 rather than the part where the discharge 400 of the tempered glass 10 is formed, that is, the part immediately below the discharge electrode 100. Good. By cooling the tempered glass 10, the action of tensile stress as a reaction of thermal stress due to internal heating of the tempered glass 10 is promoted.
Here, as a method of cooling the tempered glass 10, a method of spraying a coolant such as gas, liquid, aerosol or the like on the main surface 11 a of the tempered glass 10 can be mentioned.

　図６に示した構成では、該放電電極１００と強化ガラス１０の主表面１１ａと、の間に放電４００を形成しつつ、該放電電極１００を強化ガラス１０の切断予定線３０に沿って矢印方向に移動させることによって、強化ガラス１０の内部加熱される部位も切断予定線３０に沿って移動させる。一方、レーザ光を照射して強化ガラスを内部加熱する場合、、強化ガラス１０の主表面１１ａ上、具体的には、該主表面１１ａの切断予定線３０上にレーザ光を照射することによって、強化ガラス１０を内部加熱しつつ、レーザ光の照射部位を切断予定線３０に沿って矢印方向に移動させることによって、強化ガラス１０の内部加熱される部位を切断予定線３０に沿って移動させる。
　強化ガラス１０の内部加熱に使用するレーザ光は、照射により強化ガラス１０を内部加熱できるものである限り特に限定されない。レーザ光の波長としては、２５０～５０００ｎｍであることが照射による強化ガラス１０を内部加熱するのに好ましい。レーザ光の波長は、より好ましくは３００～４０００ｎｍ、さらに好ましくは８００～３０００ｎｍである。上記の波長域のレーザ光の光源としては、例えば、ＵＶレーザ（波長：３５５ｎｍ）、グリーンレーザ（波長：５３２ｎｍ）、半導体レーザ（波長：８０８ｎｍ、９４０ｎｍ、９７５ｎｍ）、ファイバーレーザ（波長：１０６０～１１００ｎｍ）、ＹＡＧレーザ（波長：１０６４ｎｍ、２０８０ｎｍ、２９４０ｎｍ）などが挙げられる。レーザ光の発振方式に制限はなく、レーザ光を連続発振するＣＷレーザ、レーザ光を断続発振するパルスレーザのいずれも使用可能である。また、レーザ光の強度分布に制限はなく、ガウシアン型であっても、トップハット型であっても良い。
　なお、レーザ光照射で強化ガラスを内部加熱する場合も、レーザ光照射部位よりも、切断予定線３０に沿った後方で、強化ガラス１０を冷却してもよい。 In the configuration shown in FIG. 6, while forming a discharge 400 between the discharge electrode 100 and the main surface 11 a of the tempered glass 10, the discharge electrode 100 is moved in the direction of the arrow along the planned cutting line 30 of the tempered glass 10. By moving the tempered glass 10, the part that is heated inside the tempered glass 10 is also moved along the planned cutting line 30. On the other hand, when the tempered glass is internally heated by irradiating the laser beam, by irradiating the laser beam on the main surface 11a of the tempered glass 10, specifically, the planned cutting line 30 of the main surface 11a, While the tempered glass 10 is internally heated, the site to which the laser light is irradiated is moved along the planned cutting line 30 in the direction of the arrow, thereby moving the internally heated site of the tempered glass 10 along the planned cutting line 30.
The laser beam used for internal heating of the tempered glass 10 is not particularly limited as long as the tempered glass 10 can be internally heated by irradiation. The wavelength of the laser light is preferably 250 to 5000 nm for internally heating the tempered glass 10 by irradiation. The wavelength of the laser beam is more preferably 300 to 4000 nm, still more preferably 800 to 3000 nm. Examples of the light source of the laser beam in the above wavelength range include a UV laser (wavelength: 355 nm), a green laser (wavelength: 532 nm), a semiconductor laser (wavelength: 808 nm, 940 nm, 975 nm), and a fiber laser (wavelength: 1060 to 1100 nm). ), YAG laser (wavelengths: 1064 nm, 2080 nm, 2940 nm) and the like. The laser light oscillation method is not limited, and any of a CW laser that continuously oscillates laser light and a pulse laser that intermittently oscillates laser light can be used. The intensity distribution of the laser beam is not limited, and may be a Gaussian type or a top hat type.
Even when the tempered glass is internally heated by laser beam irradiation, the tempered glass 10 may be cooled behind the laser beam irradiation site along the planned cutting line 30.

　近年、携帯電話やＰＤＡなどの携帯機器において、ディスプレイ（タッチパネルを含む）の保護や美観などを高めるため、カバーガラス（保護ガラス）を用いることが多くなっている。また、ディスプレイの基板として、ガラス基板が広く用いられている。
　一方、携帯機器の薄型化・軽量化が進行しており、携帯機器に用いられるガラスの薄板化が進行している。ガラスが薄くなると強度が低くなるので、ガラスの強度不足を補うため、圧縮応力が残留する表面層および裏面層を有する強化ガラスが開発されている。強化ガラスは、自動車用窓ガラスや建築用窓ガラスとしても用いられている。
　このような幅広い用途に用いられる強化ガラスの切断に本発明は好適である。 In recent years, in a portable device such as a mobile phone or a PDA, a cover glass (protective glass) is often used in order to enhance the protection and aesthetics of a display (including a touch panel). A glass substrate is widely used as a display substrate.
On the other hand, the reduction in thickness and weight of portable devices has progressed, and the glass used in portable devices has become thinner. Since the strength decreases as the glass becomes thinner, tempered glass having a front surface layer and a back surface layer in which compressive stress remains has been developed to compensate for the insufficient strength of the glass. Tempered glass is also used as automotive window glass and architectural window glass.
The present invention is suitable for cutting tempered glass used for such a wide range of applications.

　以下に、実施例などにより本発明を具体的に説明するが、本発明はこれらの例によって限定されるものではない。 Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited to these examples.

　本実施例において、切断対象とした強化ガラスは以下の通りである。
寸法：縦５０ｍｍ×横５０ｍｍ×厚さ０．９ｍｍ
組成（質量％表示）：ＳｉＯ2 ６４．５％、Ａｌ2Ｏ3６．０％、ＭｇＯ １１．０％、Ｎａ2Ｏ １２．０％、Ｋ2Ｏ ４％、ＺｒＯ2 ２．５％
圧縮応力層：最大残留圧縮応力６５６ＭＰａ、層厚６７μｍ
（実施例１）
　本実施例では、強化ガラスの内部側に、該強化ガラスの厚さ方向における位置が異なる２個所（表面側、奥側）にパルスレーザ光を集光して初期クラックを形成した。使用したパルスレーザ光は以下の通りである。
波長：５３２ｎｍ
ピークパワー密度：３．６×１０14Ｗ／ｍ2（表面側に使用）、３．０×１０14Ｗ／ｍ2（奥側に使用）
パルス幅：１３ｎｓ
理論集光径：５．７μｍ
　形成された初期クラックは、強化ガラスの平面視での初期クラックの位置が同一であり、強化ガラスの端部から０．２ｍｍの位置であった。また、強化ガラスの厚さ方向における位置は、強化ガラスの表面から初期クラックの下端までの距離で０．１５ｍｍ（表面側）、０．７５ｍｍ（奥側）であった。
　強化ガラスの厚さ方向における初期クラックの長さは０．１４ｍｍ（表面側）、０．２０ｍｍ（奥側）であった。強化ガラスの厚さをｔ（ｍｍ）とするとき、初期クラックの合計長さは０．３８ｔに相当する。
　次に、内部加熱による強化ガラスの切断を試みた。強化ガラスの内部加熱には下記のレーザ光の照射を用いた。
光源：ファイバーレーザ（中心波長帯：１０７０ｎｍ）
ビーム径：０．２ｍｍ
走査速度：２．５ｍｍ／ｓｅｃ（強化ガラスの端面側から切断予定線に沿って走査した）
出力：１５０～２００Ｗ
　その結果、欠け等を生じることなく、優れた切断精度で強化ガラスを切断することができた。 In this example, the tempered glass to be cut is as follows.
Dimensions: 50mm long x 50mm wide x 0.9mm thick
Composition (wt% Display): SiO 2 64.5%, Al 2 O 3 6.0%, 11.0% MgO, Na 2 O 12.0%, K 2 O 4%, ZrO 2 2.5%
Compressive stress layer: Maximum residual compressive stress 656 MPa, layer thickness 67 μm
(Example 1)
In this example, the initial crack was formed by condensing the pulse laser beam at two locations (surface side and back side) where the positions in the thickness direction of the tempered glass differed on the inner side of the tempered glass. The pulse laser light used is as follows.
Wavelength: 532nm
Peak power density: 3.6 × 10 14 W / m 2 (used on the front side), 3.0 × 10 14 W / m 2 (used on the back side)
Pulse width: 13ns
Theoretical light collection diameter: 5.7 μm
The position of the initial crack in plan view of the tempered glass was the same as the formed initial crack, and the position was 0.2 mm from the end of the tempered glass. Moreover, the position in the thickness direction of tempered glass was 0.15 mm (surface side) and 0.75 mm (back side) by the distance from the surface of tempered glass to the lower end of an initial crack.
The length of the initial crack in the thickness direction of the tempered glass was 0.14 mm (surface side) and 0.20 mm (back side). When the thickness of the tempered glass is t (mm), the total length of the initial cracks corresponds to 0.38 t.
Next, the tempered glass was cut by internal heating. The following laser beam irradiation was used for internal heating of the tempered glass.
Light source: Fiber laser (central wavelength band: 1070 nm)
Beam diameter: 0.2mm
Scanning speed: 2.5 mm / sec (scanned along the planned cutting line from the end face side of the tempered glass)
Output: 150-200W
As a result, it was possible to cut the tempered glass with excellent cutting accuracy without causing chipping or the like.

（実施例２）
　形成される初期クラック（奥側）の強化ガラスの厚さ方向における位置が実施例１とは異なるように、パルスレーザ光を集光する位置を変えた以外は実施例１と同様の手順を実施した。
　形成された初期クラックは、強化ガラスの平面視での初期クラックの位置が同一であり、強化ガラスの端部から０．２ｍｍの位置であった。また、強化ガラスの厚さ方向における位置は、強化ガラスの表面から初期クラックの下端までの距離で０．１５ｍｍ（表面側）、０．４５ｍｍ（奥側）であった。
　強化ガラスの厚さ方向における初期クラックの長さは０．１４ｍｍ（表面側）、０．２０ｍｍ（奥側）であった。強化ガラスの厚さをｔ（ｍｍ）とするとき、初期クラックの合計長さは０．３８ｔに相当する。
　実施例１と同様の手順で内部加熱による強化ガラスの切断を試みた。
　その結果、欠け等を生じることなく、優れた切断精度で強化ガラスを切断することができた。 (Example 2)
The same procedure as in Example 1 was performed except that the position where the pulse laser beam was focused was changed so that the position of the initial crack (back side) formed in the thickness direction of the tempered glass was different from that in Example 1. did.
The position of the initial crack in plan view of the tempered glass was the same as the formed initial crack, and the position was 0.2 mm from the end of the tempered glass. Moreover, the position in the thickness direction of tempered glass was 0.15 mm (surface side) and 0.45 mm (back side) in the distance from the surface of tempered glass to the lower end of the initial crack.
The length of the initial crack in the thickness direction of the tempered glass was 0.14 mm (surface side) and 0.20 mm (back side). When the thickness of the tempered glass is t (mm), the total length of the initial cracks corresponds to 0.38 t.
The tempered glass was cut by internal heating in the same procedure as in Example 1.
As a result, it was possible to cut the tempered glass with excellent cutting accuracy without causing chipping or the like.

（比較例１）
　強化ガラスの内部側の１個所（表面側）のみにパルスレーザ光を集光して初期クラックを形成した以外は実施例１と同様の手順を実施した。
　形成された初期クラックは、強化ガラスの平面視での初期クラックの位置が同一であり、強化ガラスの端部から０．２ｍｍの位置であった。また、強化ガラスの厚さ方向における位置は、強化ガラスの表面から初期クラックの下端までの距離で０．１５ｍｍであった。強化ガラスの厚さ方向における初期クラックの長さは０．１４ｍｍであった。
　実施例１と同様の手順で内部加熱による強化ガラスの切断を試みた。強化ガラスの厚さをｔ（ｍｍ）とするとき、初期クラックの長さは０．１６ｔに相当する。
　その結果、強化ガラスに欠けが生じ、切断精度が低かった。 (Comparative Example 1)
The same procedure as in Example 1 was carried out except that the initial crack was formed by condensing the pulse laser beam only at one location (surface side) inside the tempered glass.
The position of the initial crack in plan view of the tempered glass was the same as the formed initial crack, and the position was 0.2 mm from the end of the tempered glass. Moreover, the position in the thickness direction of the tempered glass was 0.15 mm as a distance from the surface of the tempered glass to the lower end of the initial crack. The length of the initial crack in the thickness direction of the tempered glass was 0.14 mm.
The tempered glass was cut by internal heating in the same procedure as in Example 1. When the thickness of the tempered glass is t (mm), the length of the initial crack corresponds to 0.16 t.
As a result, the tempered glass was chipped and the cutting accuracy was low.

（比較例２）
　強化ガラスの内部側の５個所にパルスレーザ光を集光して初期クラックを形成した。使用したパルスレーザ光は以下の通り。
波長：５３２ｎｍ
ピークパワー密度：１．３×１０14Ｗ／ｍ2
パルス幅：３３ｎｓ
理論集光径：５．７μｍ
　形成された初期クラックは、強化ガラスの平面視での初期クラックの位置が同一であり、強化ガラスの端部から０．２ｍｍの位置であった。また、強化ガラスの厚さ方向における位置は、強化ガラスの表面から初期クラックの下端までの距離でそれぞれ、０．１５ｍｍ、０．３ｍｍ、０．４５ｍｍ、０．６ｍｍ、０．７５ｍｍであった。強化ガラスの厚さ方向における初期クラックの長さは、５個所のクラックが連結され、０．７４ｍｍであった。
　強化ガラスの厚さをｔ（ｍｍ）とするとき、初期クラックの長さは０．８２ｔに相当する。
　その結果、初期クラック作成後に強化ガラスに欠けが生じ、切断できなかった。 (Comparative Example 2)
An initial crack was formed by condensing the pulse laser beam at five locations inside the tempered glass. The pulse laser light used is as follows.
Wavelength: 532nm
Peak power density: 1.3 × 10 14 W / m 2
Pulse width: 33ns
Theoretical light collection diameter: 5.7 μm
The position of the initial crack in plan view of the tempered glass was the same as the formed initial crack, and the position was 0.2 mm from the end of the tempered glass. Further, the positions in the thickness direction of the tempered glass were 0.15 mm, 0.3 mm, 0.45 mm, 0.6 mm, and 0.75 mm, respectively, as distances from the surface of the tempered glass to the lower end of the initial crack. The length of the initial crack in the thickness direction of the tempered glass was 0.74 mm, with five cracks connected.
When the thickness of the tempered glass is t (mm), the length of the initial crack corresponds to 0.82 t.
As a result, the tempered glass was chipped after the initial crack was created and could not be cut.

　本発明を特定の態様を参照して詳細に説明したが、本発明の精神と範囲を離れることなく様々な変更および修正が可能であることは、当業者にとって明らかである。
　なお、本出願は、２０１１年８月３１日付けで出願された日本特許出願（特願２０１１－１８９４４０）に基づいており、その全体が引用により援用される。 Although the invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
The present application is based on a Japanese patent application (Japanese Patent Application No. 2011-189440) filed on August 31, 2011, which is incorporated by reference in its entirety.

　１０　　　　　：強化ガラス
　１１ａ，１１ｂ：主表面
　１２ａ，１２ｂ：圧縮応力層
　１３　　　　　：内部側
　２０ａ，２０ｂ：初期クラック
　３０　　　　　：切断予定線
　４０　　　　　：クラック
　１００　　　　：放電電極
　２００　　　　：対向電極
　３００　　　　：高周波交流電源
　４００　　　　：放電 DESCRIPTION OF SYMBOLS 10: Tempered glass 11a, 11b: Main surface 12a, 12b: Compression stress layer 13: Inner side 20a, 20b: Initial crack 30: Planned cutting line 40: Crack 100: Discharge electrode 200: Counter electrode 300: High frequency alternating current power supply 400: Discharge

Claims (7)

　板状ガラス部材の表面に圧縮応力層が形成された強化ガラスを切断する方法であって、
　前記強化ガラスの前記圧縮応力層よりも内部側に、レーザ光を集光して初期クラックを形成する工程、および、初期クラックの形成後、前記強化ガラスを内部加熱し、前記強化ガラスの内部加熱される部位を切断予定線に沿って移動させることにより、前記強化ガラスを切断する工程を含み、
　前記初期クラックを形成する工程では、前記強化ガラスの厚さをｔとするとき、該強化ガラスの厚さ方向における前記初期クラックの合計長さが、０．２ｔ～０．８ｔとなるように、前記強化ガラスの表面の平面視での位置が略同一であって、かつ、前記強化ガラスの厚さ方向における位置が異なる少なくとも２個所に初期クラックを形成する、強化ガラスの切断方法。 A method of cutting tempered glass in which a compression stress layer is formed on the surface of a sheet glass member,
A step of condensing laser light to form an initial crack on the inner side of the compressive stress layer of the tempered glass, and after the formation of the initial crack, the tempered glass is internally heated, and the tempered glass is internally heated. A step of cutting the tempered glass by moving a portion to be cut along a planned cutting line,
In the step of forming the initial crack, when the thickness of the tempered glass is t, the total length of the initial cracks in the thickness direction of the tempered glass is 0.2 t to 0.8 t. A method for cutting tempered glass, wherein initial cracks are formed in at least two locations where the positions of the surface of the tempered glass in a plan view are substantially the same and the positions in the thickness direction of the tempered glass are different. 　前記初期クラックの形成工程では、波長域が２５０～３０００ｎｍ、かつ、ピークパワー密度が１×１０12～１×１０16Ｗ／ｍ2のパルスレーザ光を用いる、請求項１に記載の強化ガラスの切断方法。 2. The tempered glass according to claim 1, wherein the initial crack formation step uses pulsed laser light having a wavelength range of 250 to 3000 nm and a peak power density of 1 × 10 12 to 1 × 10 16 W / m 2 . Cutting method. 　前記初期クラックの形成工程では、波長域が２５０～３０００ｎｍ、かつ、パルス幅が１０００ｎｓ以下のパルスレーザ光を用いる、請求項１に記載の強化ガラスの切断方法。 2. The method for cutting tempered glass according to claim 1, wherein in the initial crack formation step, a pulsed laser beam having a wavelength range of 250 to 3000 nm and a pulse width of 1000 ns or less is used. 　前記初期クラックの形成工程では、前記強化ガラスの端面よりレーザ光を入射して、前記強化ガラスの前記圧縮応力層よりも内部側にレーザ光を集光させて初期クラックを形成する、請求項１～３のいずれか１項に記載の強化ガラスの切断方法。 2. The initial crack is formed in the step of forming the initial crack by making laser light incident from an end face of the tempered glass and condensing the laser beam on the inner side of the compressive stress layer of the tempered glass. 4. The method for cutting tempered glass according to any one of items 1 to 3. 　前記初期クラックの形成工程では、少なくとも２つのレーザ光を同時に前記強化ガラスの内部側に集光させて、少なくとも２個所に初期クラックを同時に形成する、請求項１～４のいずれか１項に記載の強化ガラスの切断方法。 5. The initial crack forming step, wherein at least two laser beams are simultaneously focused on the inner side of the tempered glass, and initial cracks are simultaneously formed in at least two places. Cutting method of tempered glass. 　前記強化ガラスの内部加熱にレーザ光の照射を用いる、請求項１～５のいずれか１項に記載の強化ガラスの切断方法。 The method for cutting tempered glass according to any one of claims 1 to 5, wherein laser beam irradiation is used for internal heating of the tempered glass. 　前記強化ガラスの内部加熱に放電を用いる、請求項１～５のいずれか１項に記載の強化ガラスの切断方法。 The method for cutting tempered glass according to any one of claims 1 to 5, wherein discharge is used for internal heating of the tempered glass.
PCT/JP2012/071704 2011-08-31 2012-08-28 Method for cutting reinforced glass Ceased WO2013031771A1 (en)

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JP2006256944A (en) * 2005-03-14 2006-09-28 Lemi Ltd Method and device for cutting brittle material
JP2007260749A (en) * 2006-03-29 2007-10-11 Toshiba Corp Laser processing method, laser processing apparatus, and processed product of brittle material
WO2012096284A1 (en) * 2011-01-11 2012-07-19 旭硝子株式会社 Cutting method for strengthened glass plate

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JP2006256944A (en) * 2005-03-14 2006-09-28 Lemi Ltd Method and device for cutting brittle material
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WO2012096285A1 (en) * 2011-01-11 2012-07-19 旭硝子株式会社 Cutting method for strengthened glass plate
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