WO2016117479A1 - Glass substrate production method - Google Patents

Glass substrate production method Download PDF

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Publication number
WO2016117479A1
WO2016117479A1 PCT/JP2016/051179 JP2016051179W WO2016117479A1 WO 2016117479 A1 WO2016117479 A1 WO 2016117479A1 JP 2016051179 W JP2016051179 W JP 2016051179W WO 2016117479 A1 WO2016117479 A1 WO 2016117479A1
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Prior art keywords
glass
glass substrate
producing
inorganic salt
acid
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PCT/JP2016/051179
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French (fr)
Japanese (ja)
Inventor
出 鹿島
祐輔 藤原
玉井　喜芳
鈴木　祐一
洋一 世良
拓 山田
小林　大介
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旭硝子株式会社
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Application filed by 旭硝子株式会社 filed Critical 旭硝子株式会社
Priority to CN201680006377.5A priority Critical patent/CN107207335B/en
Priority to JP2016570615A priority patent/JPWO2016117479A1/en
Publication of WO2016117479A1 publication Critical patent/WO2016117479A1/en

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

Definitions

  • the present invention relates to a method for producing a glass substrate.
  • a thin plate-like cover glass is formed so as to have a wider area than the image display portion in order to enhance display protection and beauty. Is placed in front of the display.
  • the cover glass With the demand for weight reduction and thinning of flat panel display devices, it is also required to make the cover glass itself thinner. Accordingly, the cover glass is required to have further strength on both the surface and the end surface in order to satisfy the purpose.
  • Chemically tempered glass is obtained by subjecting raw glass produced by a production method such as the float method or fusion method to processing such as cutting treatment or chamfering treatment for cutting into a desired shape, followed by chemical strengthening treatment. It is manufactured.
  • Patent Document 1 and Patent Document 2 describe a method of manufacturing chemically strengthened glass in which surface compressive stress is increased by performing chemical strengthening treatment in two stages after processing such as cutting on raw glass. Has been.
  • an object of this invention is to provide the manufacturing method of the glass base material whose surface strength is higher than raw glass and can suppress generation
  • An object of the present invention is to provide a glass substrate having high surface strength.
  • the inventors of the present invention have found that the surface strength of glass is improved by performing an ion exchange treatment with an inorganic salt containing a specific salt and then performing treatment with an acid and an alkali, thereby completing the present invention. .
  • a method for producing a glass substrate comprising a step of ion-exchanging Na ions in the raw glass and K ions in the inorganic salt by contacting the raw glass with an inorganic salt containing potassium nitrate,
  • the inorganic salt is at least selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 , NaHCO 3 , K 3 PO 4 , Na 3 PO 4 , K 2 SO 4 , Na 2 SO 4 , KOH and NaOH.
  • a method for producing a glass substrate comprising: a step of acid-treating glass after the washing step; and a step of alkali-treating glass after the step of acid treatment.
  • a method for producing a glass substrate comprising a step of ion-exchanging Na ions in the raw glass and K ions in the inorganic salt by bringing the raw glass into contact with an inorganic salt,
  • the inorganic salt has a K / Na ratio of 1 to 15 in terms of mass ratio, and the step of washing the glass after the ion exchange step;
  • a method for producing a glass substrate comprising: a step of acid-treating glass after the washing step; and a step of alkali-treating glass after the step of acid treatment.
  • the said inorganic salt is a manufacturing method of the glass base material of the said ⁇ 4> description containing potassium nitrate.
  • ⁇ 6> The method for producing a glass substrate according to ⁇ 1> or ⁇ 4>, wherein the acid treatment step uses a solution having a pH of less than 7.
  • ⁇ 7> The method for producing a glass substrate according to ⁇ 6>, wherein the solution having a pH of less than 7 is a weak acid.
  • ⁇ 8> The method for producing a glass substrate according to ⁇ 6>, wherein the solution having a pH of less than 7 is a strong acid.
  • ⁇ 9> The method for producing a glass substrate according to ⁇ 1> or ⁇ 4>, wherein the acid-treating step is performed at a temperature of 100 ° C. or lower.
  • ⁇ 10> The method for producing a glass substrate according to ⁇ 1> or ⁇ 4>, wherein the time for performing the acid treatment is 10 seconds to 5 hours.
  • ⁇ 11> The method for producing a glass substrate according to ⁇ 1> or ⁇ 4>, wherein the alkali treatment step uses a solution having a pH exceeding 7.
  • ⁇ 12> The method for producing a glass substrate according to ⁇ 11>, wherein the solution having a pH exceeding 7 is a weak base.
  • ⁇ 13> The method for producing a glass substrate according to ⁇ 11>, wherein the solution having a pH exceeding 7 is a strong base.
  • ⁇ 14> The method for producing a glass substrate according to ⁇ 1> or ⁇ 4>, wherein the alkali treatment step is performed at a temperature of 0 ° C. or higher and 100 ° C. or lower.
  • ⁇ 15> The method for producing a glass substrate according to ⁇ 1> or ⁇ 4>, wherein the time for performing the alkali treatment step is 10 seconds to 5 hours.
  • a glass substrate having higher surface strength than raw glass can be obtained.
  • the manufacturing method of this invention although it has a compressive-stress layer, the glass base material with a low compressive-stress value (CS) of the outermost surface is obtained. Since this glass substrate has a compressive stress layer, it is difficult for cracks to occur on the glass surface, and handling flaws can be suppressed. Furthermore, the glass can be prevented from breaking during subsequent processing, and subsequent processing can be performed smoothly while suppressing the occurrence of handling flaws.
  • the compressive stress value (CS) on the outermost surface is low, the internal tensile stress (CT) can be kept low, so that processing such as cutting is easy.
  • FIG. 1 is a schematic diagram for explaining a ball-on-ring test method.
  • raw glass is glass that does not have a compressive stress layer due to ion exchange on the surface.
  • Glass substrate is obtained by subjecting raw glass to ion exchange treatment, acid treatment, and alkali treatment. This glass substrate has a compressive stress layer ion-exchanged on the surface, and has a low compressive stress value (CS) on the outermost surface. Since the compressive stress value (CS) on the outermost surface is low, the internal tensile stress (CT) can be kept low, and processing such as cutting is easy.
  • the “chemically tempered glass” refers to a raw glass or a glass substrate that has been subjected to a chemical tempering treatment.
  • This chemically strengthened glass has a compressive stress layer ion-exchanged on the surface, and has a high compressive stress value (CS) on the outermost surface. Since the compressive stress value (CS) on the outermost surface is high, the internal tensile stress (CT) is also high, and processing such as cutting is not easy.
  • Glass composition The glass used in the present invention only needs to contain sodium, and glass having various compositions can be used as long as it has a composition that can be strengthened by molding and chemical strengthening treatment. Specific examples include aluminosilicate glass, soda lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass.
  • the production method of raw glass is not particularly limited, and a desired glass raw material is put into a continuous melting furnace, and the glass raw material is heated and melted preferably at 1500 to 1600 ° C., clarified, and then supplied to a molding apparatus. Can be produced by forming and slowly cooling.
  • various methods can be employed for forming raw glass.
  • various forming methods such as a down draw method (for example, an overflow down draw method, a slot down method and a redraw method), a float method, a roll-out method, and a press method can be employed.
  • the thickness of the raw glass is not particularly limited, but is usually preferably 5 mm or less and more preferably 3 mm or less in order to effectively perform the ion exchange treatment and the chemical strengthening treatment.
  • the shape of the glass used in the present invention is not particularly limited.
  • various shapes of glass such as a flat plate shape having a uniform plate thickness, a shape having a curved surface on at least one of the front surface and the back surface, and a three-dimensional shape having a bent portion can be employed.
  • 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 is 12 to 25%, and the total content of MgO and CaO is 7 to 15%.
  • composition which is displayed at a certain glass (iii) mol%, a SiO 2 68 ⁇ 80%, the Al 2 O 3 4 ⁇ 10% ,
  • the a 2 O 5 ⁇ 15%, the K 2 O 0 to 1%, the MgO 4 ⁇ 15% and ZrO 2 is composition displaying a glass (iv) mole% containing 0 to 1%, a SiO 2 67 -75%, Al 2 O 3 0-4%, Na 2 O 7-15%, K 2 O 1-9%, MgO 6-14% and ZrO 2 0-1.5%
  • the total content of SiO 2 and Al 2 O 3 is 71 to 75%, the total content of Na 2 O and K 2 O is 12 to 20%, and when CaO is contained, the content is 1% Glass that is less than
  • the glass substrate according to the present invention has a compressive stress layer ion-exchanged on the surface, and has a low compressive stress value (CS) on the outermost surface.
  • the surface of glass is ion exchanged to form a compressive stress layer in which compressive stress remains.
  • alkali metal ions typically Li ions and Na ions
  • alkali ions typically Li ions and Na ions
  • Li ions are Na ions or K ions
  • Na ions are substituted with K ions).
  • the glass surface is slightly ion-exchanged by contacting with a specific inorganic salt as shown below, and has a compressive stress layer, and the compressive stress on the outermost surface.
  • a glass substrate having a low value (CS) can be obtained.
  • an inorganic salt containing potassium nitrate (KNO 3 ) and having a K / Na ratio in a specific range by mass ratio is brought into contact with raw glass.
  • KNO 3 potassium nitrate
  • K ions on the glass surface and K ions in the inorganic salt are ion-exchanged to form a high-density compressive stress layer.
  • the inorganic salt further includes a specific salt (flux) described later.
  • a method of bringing the raw glass into contact with the inorganic salt As a method of bringing the raw glass into contact with the inorganic salt, a method of applying a paste-like inorganic salt, a method of spraying an aqueous solution of an inorganic salt onto the raw glass, or immersing the raw glass in a salt bath of a molten salt heated to a melting point or higher Although a method etc. are possible, Among these, the method of immersing in molten salt is desirable.
  • the inorganic salt those having a melting point below the glass strain point (usually 500 to 600 ° C.) are preferred, and salts containing potassium nitrate (melting point 330 ° C.) are preferred. By containing potassium nitrate, it is in a molten state below the strain point of the glass, and handling is easy in the operating temperature range.
  • the content of potassium nitrate in the inorganic salt is more preferably 50% by mass or more.
  • the inorganic salt is further selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 , NaHCO 3 , K 3 PO 4 , Na 3 PO 4 , K 2 SO 4 , Na 2 SO 4 , KOH and NaOH. More preferably, it contains at least one salt. Among these, it is more preferable to contain at least one salt selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 and NaHCO 3 .
  • the above-mentioned salt (hereinafter sometimes referred to as “flux”) has a property of cutting a glass network represented by Si—O—Si bonds.
  • the formation of a low-density layer, which will be described later, is promoted by appropriately breaking the covalent bond between Si—O of the glass.
  • the degree of breaking the covalent bond varies depending on the glass composition, the type of salt (flux) used, the temperature at which the inorganic salt is brought into contact, the processing conditions such as the time, and the like. It is considered preferable to select conditions that can break one or two bonds.
  • the amount of the flux added is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, more preferably 1 mol% or more, and particularly preferably 2 mol% or more from the viewpoint of securing the removal amount of the low density layer described later. Further, from the viewpoint of productivity, the saturation solubility or less of each salt is preferable. Addition in excess may lead to glass corrosion.
  • the content of the flux in the inorganic salt is 0.1 mol% or more, preferably 24 mol% or less, more preferably 12 mol% or less, and more preferably 8 mol% or less. Particularly preferred.
  • the glass contact temperature is 350 to 500 ° C.
  • the glass contact time is preferably 1 minute to 50 hours, more preferably 5 minutes to 40 hours, and even more preferably 10 minutes to 30 hours.
  • the upper limit is more preferably 10 hours, more preferably 8 hours, and particularly preferably 4 hours.
  • the content of the flux in the inorganic salt is 0.1 mol% or more, preferably 24 mol% or less, more preferably 12 mol% or less, and more preferably 8 mol% or less. Particularly preferred.
  • the glass contact temperature is 350 to 500 ° C.
  • the glass contact time is preferably 1 minute to 50 hours, more preferably 5 minutes to 40 hours, and even more preferably 10 minutes to 30 hours.
  • the upper limit is more preferably 10 hours, more preferably 8 hours, and particularly preferably 4 hours.
  • the inorganic salt has a K / Na ratio of 1 to 15 by mass, preferably 2 to 12 and more preferably 2 to 10.
  • CS compressive stress value
  • the K / Na mass ratio can be adjusted, for example, by adding NaNO 3 , KNO 3 , the above-described flux and the like to the inorganic salt.
  • the inorganic salt may contain other chemical species as long as the effect of the present invention is not impaired.
  • alkali salts such as sodium chloride, potassium chloride, sodium borate, potassium borate, etc.
  • An alkali borate etc. are mentioned. These may be added alone or in combination of two or more.
  • the molten salt can be produced by the steps shown below.
  • Step 1a Preparation of potassium nitrate molten salt
  • Step 2a Addition of flux to potassium nitrate molten salt
  • Step 1a-Preparation of molten potassium nitrate salt an inorganic salt containing potassium nitrate is put into a container, and heated to a temperature equal to or higher than the melting point to be melted to prepare a molten salt. Melting is performed at a temperature within the range of the melting point (330 ° C.) and boiling point (500 ° C.) of potassium nitrate. In particular, the melting temperature is preferably 350 to 500 ° C. from the viewpoint of the balance between the surface compressive stress (CS) and the compressive stress layer depth (DOL) that can be applied to the glass and the strengthening time, and more preferably 350 to 470 ° C. .
  • metal As the container for melting the inorganic salt, metal, quartz, ceramics, or the like can be used. Among these, a metal material is desirable from the viewpoint of durability, and a stainless steel (SUS) material is preferable from the viewpoint of corrosion resistance.
  • SUS stainless steel
  • Step 2a-Addition of flux to potassium nitrate molten salt- the above-mentioned flux and chemical species for adjusting the K / Na ratio are added to the potassium nitrate molten salt prepared in step 1a, and the entire temperature is maintained with a stirring blade while maintaining the temperature within a certain range. Mix until uniform.
  • the order of addition is not limited, and they may be added simultaneously.
  • the temperature is preferably equal to or higher than the melting point of potassium nitrate, that is, 330 ° C. or higher, and more preferably 350 to 500 ° C.
  • the stirring time is preferably 1 minute to 50 hours, more preferably 10 minutes to 30 hours.
  • the upper limit is more preferably 10 hours, and particularly preferably 2 hours.
  • Step 1b Mixing of inorganic salt containing potassium nitrate and flux
  • Step 2b Melting of mixed salt of inorganic salt containing potassium nitrate and flux
  • Step 1b-Mixing of inorganic salt containing potassium nitrate and flux- an inorganic salt containing potassium nitrate and a flux are put into a container and mixed with a stirring blade or the like.
  • a stirring blade or the like When using a plurality of fluxes in combination, the order of addition is not limited, and they may be added simultaneously.
  • the same container as that used in the above step 1a can be used.
  • Step 2b-Melting of mixed salt of inorganic salt containing potassium nitrate and flux- the mixed salt obtained in step 1b is heated and melted. Melting is performed at a temperature within the range of the melting point (330 ° C.) and boiling point (500 ° C.) of potassium nitrate.
  • the melting temperature is preferably 350 to 470 ° C. from the viewpoint of the balance between the surface compressive stress (CS) and the compressive stress layer depth (DOL) that can be applied to the glass, and the strengthening time.
  • the stirring time is preferably 1 minute to 10 hours, and more preferably 10 minutes to 2 hours.
  • the precipitate is a container before the ion exchange treatment of raw glass. Let it settle until it settles at the bottom.
  • This precipitate includes a flux exceeding the saturation solubility and a salt in which the cations of the flux are exchanged in the molten salt.
  • an ion exchange treatment is performed using the prepared molten salt.
  • the ion exchange treatment is performed by immersing raw glass in a molten salt and replacing metal ions (Na ions) in the raw glass with metal ions (K ions) having a large ion radius in the molten salt.
  • Na ions metal ions
  • K ions metal ions
  • the density of the glass gradually increases from the outer edge of the intermediate layer (bulk) present at the center of the glass toward the surface of the compressive stress layer, so that the gap between the intermediate layer and the compressive stress layer is There is no clear boundary where the density changes rapidly.
  • the intermediate layer is a layer present in the center of the glass and sandwiched between the compressive stress layers. Unlike the compressive stress layer, this intermediate layer is a layer that is not ion-exchanged.
  • the ion exchange treatment in the present invention can be performed by the following step 3.
  • Process 3 Raw glass ion exchange treatment
  • step 3 raw glass is preheated, and the molten salt prepared in steps 1a and 2a or steps 1b and 2b is adjusted to a temperature at which chemical strengthening is performed.
  • step 3 after the preheated raw glass is immersed in the molten salt for a predetermined time, it is pulled up from the molten salt and allowed to cool.
  • the preheating temperature of raw glass depends on the temperature immersed in the molten salt, but is generally preferably 100 ° C. or higher.
  • the ion exchange treatment temperature is preferably higher than the melting point of potassium nitrate, that is, 330 ° C. or higher.
  • the strain point generally 500 to 600 ° C. or less of raw glass is preferable, and minus 50 ° C. or less is more preferable than the strain point.
  • the melting temperature is preferably 350 to 500 ° C. from the viewpoint of the balance between the surface compressive stress (CS) and the compressive stress depth (DOL) that can be applied to the glass, and the strengthening time.
  • the immersion time of raw glass in the molten salt is preferably 1 minute to 50 hours, more preferably 5 minutes to 40 hours, and even more preferably 10 minutes to 30 hours.
  • the upper limit is more preferably 10 hours, more preferably 8 hours, and particularly preferably 4 hours. If it exists in this range, the glass base material excellent in the balance of an intensity
  • Step 4 Glass cleaning
  • Step 5 Acid treatment of glass after Step 4
  • the surface layer of the compressive stress layer was altered on the surface of the glass, specifically, the density was reduced. It will further have a low density layer.
  • the low density layer is formed by Na (leaching) from the outermost surface of the compressive stress layer (leaching) and H entering (replacement) instead.
  • Step 4-Glass cleaning- glass is cleaned using industrial water, ion exchange water, or the like. Of these, ion-exchanged water is preferred.
  • the washing conditions vary depending on the washing solution used, but when ion-exchanged water is used, washing at 0 to 100 ° C. is preferable from the viewpoint of completely removing the attached salt.
  • Step 5-Acid treatment- the glass cleaned in step 4 is further subjected to acid treatment.
  • the acid treatment of the glass is performed by immersing the glass in an acidic solution, whereby Na and / or K on the glass surface can be replaced with H.
  • the solution is not particularly limited as long as it is acidic, and may be less than pH 7.
  • the acid used may be a weak acid or a strong acid. Specifically, acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid, carbonic acid and citric acid are preferred. These acids may be used alone or in combination.
  • the temperature at which the acid treatment is performed varies depending on the type, concentration, and time of the acid used, but is preferably 100 ° C. or less.
  • the time for the acid treatment varies depending on the type, concentration and temperature of the acid used, but is preferably 10 seconds to 5 hours from the viewpoint of productivity, and more preferably 1 minute to 2 hours.
  • the concentration of the solution used for the acid treatment varies depending on the type of acid used, the time, and the temperature, but is preferably a concentration at which there is little concern about container corrosion, specifically 0.05 to 20% by weight.
  • the thickness of the low density layer is preferably 5 nm or more, more preferably 20 nm or more from the viewpoint of the amount of glass surface removed.
  • the thickness of the low density layer can be controlled by the flux concentration, temperature, time, etc. in the ion exchange treatment step.
  • the density of the low-density layer is preferably lower than the density of the region (bulk) deeper than the ion-exchanged compressive stress layer from the viewpoint of glass surface removability.
  • the thickness of the low density layer can be determined from the period ( ⁇ ) measured by the X-ray reflectivity method (X-ray-Reflectometry: XRR).
  • the density of the low density layer can be determined from the critical angle ( ⁇ c) measured by XRR.
  • it is also possible to confirm the formation of the low density layer and the thickness of the layer by simply observing a cross section of the glass with a scanning electron microscope (SEM).
  • Step 6 Alkali Treatment According to the above step 6, part or all of the low density layer formed up to step 5 can be removed. Hereinafter, step 6 will be described in detail.
  • Step 6-alkali treatment the glass treated with acid in step 5 is further subjected to alkali treatment.
  • the alkali treatment is performed by immersing glass in a basic solution, whereby a part or all of the low density layer can be removed.
  • the solution is not particularly limited as long as it is basic, and may have a pH exceeding 7, and a weak base or a strong base may be used.
  • bases such as sodium hydroxide, potassium hydroxide, potassium carbonate and sodium carbonate are preferred. These bases may be used alone or in combination.
  • the temperature for the alkali treatment varies depending on the type, concentration and time of the base used, but is preferably 0 to 100 ° C, more preferably 10 to 80 ° C, and particularly preferably 20 to 60 ° C. If it is this temperature range, there is no possibility that glass will corrode and it is preferable.
  • the alkali treatment time varies depending on the type, concentration and temperature of the base used, it is preferably 10 seconds to 5 hours from the viewpoint of productivity, and more preferably 1 minute to 2 hours.
  • the concentration of the solution used for the alkali treatment varies depending on the type of base used, the time, and the temperature, but is preferably from 0.1% by weight to 20% by weight from the viewpoint of glass surface removability.
  • step 4 it is preferable to have a cleaning step similar to step 4 between the acid treatment step 5 and the alkali treatment step 6 or after completion of the alkali treatment step 6.
  • the amount of the low density layer to be removed depends on the conditions of the alkali treatment. A part of the low-density layer may be removed and a part may remain. From the viewpoint of improving the strength, the effect can be obtained without removing all of the low density layer, but it is preferable to remove all of the low density layer from the viewpoint of stably securing the transmittance of the glass.
  • Compressive stress value (CS) of glass substrate, depth of compressive stress layer (DOL) is preferably 100 to 650 (MPa).
  • the compressive stress layer depth (DOL) of the glass substrate is preferably 20 to 150 ( ⁇ m), more preferably 20 to 40 ( ⁇ m).
  • the strength (surface strength) of the glass substrate of the present invention can be evaluated by a ball-on-ring test.
  • Ball-on-ring test A glass substrate is placed on a ring made of stainless steel having a diameter of 30 mm and a contact portion having a radius of curvature of 2.5 mm, and the sphere is statically kept in contact with a glass sphere made of steel having a diameter of 10 mm.
  • the BOR surface strength F (N) measured by a ball-on-ring (BOR) test in which the load is applied to the center of the ring under dynamic load conditions is evaluated.
  • the glass substrate of the present invention preferably has F ⁇ 1800 ⁇ t 2 and more preferably F ⁇ 2000 ⁇ t 2 [wherein F is the BOR surface strength (N T is the thickness (mm) of the glass substrate. ]. When the BOR surface strength F (N) is within this range, excellent strength is exhibited even when the plate is thinned.
  • FIG. 1 shows a schematic diagram for explaining the ball-on-ring test used in the present invention.
  • the glass plate 1 is placed on the glass plate 1 using a pressing jig 2 (hardened steel, diameter 10 mm, mirror finish) made of SUS304 with the glass plate 1 placed horizontally. Pressurize and measure the surface strength of the glass plate 1.
  • a glass plate 1 serving as a sample is horizontally installed on a receiving jig 3 made of SUS304 (diameter 30 mm, contact portion curvature R2.5 mm, contact portion is hardened steel, mirror finish). Above the glass plate 1, a pressurizing jig 2 for pressurizing the glass plate 1 is installed.
  • region of the glass plate 1 is pressurized from the upper direction of the glass plate 1 obtained after the Example and the comparative example.
  • the test conditions are as follows. Lowering speed of the pressure jig 2: 1.0 (mm / min) At this time, the breaking load (unit N) when the glass is broken is defined as the BOR surface strength, and the average value of 20 measurements is defined as the BOR average surface strength. However, if the glass plate fracture starting point is 2 mm or more away from the ball pressing position, it is excluded from the data for calculating the average value.
  • the glass substrate obtained by the production method of the present invention is subjected to a processing treatment such as a cutting treatment or a chamfering treatment for cutting into a desired shape, and further subjected to a chemical strengthening treatment to provide a chemical strengthening having a desired surface strength.
  • a processing treatment such as a cutting treatment or a chamfering treatment for cutting into a desired shape
  • a chemical strengthening treatment to provide a chemical strengthening having a desired surface strength.
  • the depth of the compressive stress layer in the chemically strengthened glass is preferably 30 ⁇ m or more, and more preferably 40 ⁇ m or more.
  • the surface compressive stress is preferably 600 MPa or more, and more preferably 700 MPa or more. Specifically, for example, it is immersed in a molten potassium nitrate (KNO 3 ) salt at 425 to 465 ° C. for 2 to 24 hours.
  • KNO 3 molten potassium nitrate
  • the glass substrate does not necessarily need to be chemically strengthened.
  • the compressive stress value of the compressive stress layer and the depth of the compressive stress layer of the glass substrate of the present invention can be measured using a surface stress meter (for example, FSM-6000 manufactured by Orihara Seisakusho). Further, the depth of the compressive stress layer can be substituted by an ion exchange depth measured using an EPMA (electron probe micro analyzer) or the like.
  • the surface compressive stress value (CS, unit is MPa) and the depth of the compressive stress layer (DOL, unit is ⁇ m) were measured using a surface stress meter (FSM-6000) manufactured by Orihara Seisakusho.
  • the glass removal amount thickness was determined by measuring the weight before and after the chemical treatment with an analytical electronic balance (HR-202i; manufactured by AND) and converting the thickness using the following formula.
  • (Removed thickness per side) ((weight before treatment) ⁇ (weight after treatment)) / (glass specific gravity) / treated area / 2
  • Examples 1-1, 1-2, 1-3, 2-1, 2-2, and 2-3 are examples, and Examples 1-4 and 2-4 are comparative examples. It is.
  • Example 1-1 (Raw glass preparation) A glass A having a size of 50 mm ⁇ 50 mm ⁇ 0.7 mm and having the following composition and specific gravity was used. Glass A composition (expressed in mol%): SiO 2 64.4%, Al 2 O 3 8.0%, Na 2 O 12.5%, K 2 O 4.0%, MgO 10.5%, CaO 0. 1%, SrO 0.1%, BaO 0.1%, ZrO 2 0.5% Glass A specific gravity (g / cm 3 ): 2.48, strain point: 556 ° C.
  • Example 1-2 Example 1 except that 4680 g of potassium nitrate, 177 g of potassium carbonate and 1384 g of sodium nitrate were added and heated to 450 ° C. with a mantle heater to prepare a molten salt having a potassium carbonate concentration of 2 mol% and a K / Na mass ratio of 5.3.
  • a glass substrate of Example 1-2 was obtained.
  • Example 2-1 A glass substrate of Example 2-1 was obtained in the same manner as Example 1-1 except that glass B having a size of 50 mm ⁇ 50 mm ⁇ 0.7 mm and having the following composition and specific gravity was used instead of glass A.
  • Glass B composition in mol%): SiO 2 68%, Al 2 O 3 10%, Na 2 O 14%, MgO 8%
  • Glass B specific gravity g / cm 3 ): 2.41
  • Example 2-2 Example 2 except that 4680 g of potassium nitrate, 177 g of potassium carbonate and 1384 g of sodium nitrate were added and heated to 450 ° C. with a mantle heater to prepare a molten salt of 2 mol% potassium carbonate and a K / Na mass ratio of 5.3.
  • a glass substrate of Example 2-2 was obtained.
  • Table 1 shows the evaluation results of the glass substrates obtained as described above.
  • the evaluation results of the glass A that has not been subjected to the ion exchange treatment step, the acid treatment step, and the alkali treatment step are taken as examples 1-4, and the ion exchange treatment step, the acid treatment step, and the alkali treatment step were performed
  • Table 1 shows the evaluation results of the glass B that was not used as Example 2-4.
  • the surface strength of the glass substrate of the example obtained by the production method of the present invention was greatly improved as compared with the glass of the comparative example (untreated raw glass).
  • a glass base material having significantly improved surface strength can be obtained safely and at low cost.
  • the glass substrate according to the present invention can be applied to various uses such as a cover glass for a display such as a mobile phone, a digital camera or a touch panel display, and a windshield of a vehicle.

Abstract

The purpose of the present invention is to provide a glass substrate that has high surface strength. The present invention relates to a glass substrate production method that includes: a step for bringing raw glass into contact with an inorganic salt that includes potassium nitrate and thereby performing an ion exchange between Na ions in the glass and K ions in the inorganic salt, wherein the inorganic salt includes a specific salt and has a K/Na mass ratio of 1-15; a step for cleaning the glass after the ion exchange step; a step for performing an acid treatment on the glass after the cleaning step; and a step for performing an alkali treatment on the glass after the acid treatment step.

Description

ガラス基材の製造方法Manufacturing method of glass substrate
　本発明はガラス基材の製造方法に関する。 The present invention relates to a method for producing a glass substrate.
　デジタルカメラ、携帯電話または携帯情報端末ＰＤＡ（Ｐｅｒｓｏｎａｌ　Ｄｉｇｉｔａｌ　Ａｓｓｉｓｔａｎｔｓ）等のフラットパネルディスプレイ装置において、ディスプレイの保護および美観を高めるために、画像表示部分よりも広い領域となるように薄い板状のカバーガラスをディスプレイの前面に配置することが行われている。 In a flat panel display device such as a digital camera, a mobile phone, or a personal digital assistant PDA (Personal Digital Assistants), a thin plate-like cover glass is formed so as to have a wider area than the image display portion in order to enhance display protection and beauty. Is placed in front of the display.
　フラットパネルディスプレイ装置に対する軽量化および薄型化の要求に伴い、カバーガラス自身も薄くすることが要求されている。したがってカバーガラスには、その目的を満たすために表面及び端面ともにさらなる強度が求められる。 With the demand for weight reduction and thinning of flat panel display devices, it is also required to make the cover glass itself thinner. Accordingly, the cover glass is required to have further strength on both the surface and the end surface in order to satisfy the purpose.
　ガラスは理論強度が高いものの、傷がつくことで強度が大幅に低下するため、強度が求められるカバーガラスには、イオン交換等によりガラス表面に圧縮応力層を形成した化学強化ガラスが用いられている。
　化学強化ガラスは、フロート法、フュージョン法等の製造方法により製造された生ガラスに、所望の形状に切断する切断処理や面取り処理等の加工処理を行なった後、化学強化処理が行なわれることで製造されている。 Although glass has a high theoretical strength, the strength is greatly reduced due to scratches. Therefore, a chemically strengthened glass with a compressive stress layer formed on the glass surface by ion exchange or the like is used for the cover glass that requires strength. Yes.
Chemically tempered glass is obtained by subjecting raw glass produced by a production method such as the float method or fusion method to processing such as cutting treatment or chamfering treatment for cutting into a desired shape, followed by chemical strengthening treatment. It is manufactured.
　ここで、特許文献１及び特許文献２には、生ガラスに切断等の加工処理を行った後に、化学強化処理を２段階で行うことで表面圧縮応力を高めた化学強化ガラスの製造方法が記載されている。 Here, Patent Document 1 and Patent Document 2 describe a method of manufacturing chemically strengthened glass in which surface compressive stress is increased by performing chemical strengthening treatment in two stages after processing such as cutting on raw glass. Has been.
日本国特表２０１１－５２９４３８号公報Japan Special Table 2011-529438 日本国特許第５２９３９０８号公報Japanese Patent No. 5293908
　しかしながら生ガラスは、搬送中や切断処理中及び加工処理中に傷がつくおそれがあった。このような傷は扱い傷と呼ばれ、一度扱い傷が発生するとその後に化学強化処理が施された場合でも、最終製品に影響を与えるおそれがあった。
　そこで、本発明は、生ガラスよりも面強度が高く、扱い傷の発生を抑制可能なガラス基材の製造方法を提供することを目的とする。 However, raw glass may be damaged during transportation, cutting, and processing. Such a flaw is called a flaw, and once the flaw is generated, there is a possibility that the final product may be affected even if a chemical strengthening treatment is performed thereafter.
Then, an object of this invention is to provide the manufacturing method of the glass base material whose surface strength is higher than raw glass and can suppress generation | occurrence | production of a handling flaw.
　本発明は、面強度の高いガラス基材を提供することを目的とする。 An object of the present invention is to provide a glass substrate having high surface strength.
　本発明者らは、特定の塩を含む無機塩によりイオン交換処理を行い、その後、酸とアルカリによる処理を行うことで、ガラスの面強度が改善されることを見出し、本発明を完成させた。 The inventors of the present invention have found that the surface strength of glass is improved by performing an ion exchange treatment with an inorganic salt containing a specific salt and then performing treatment with an acid and an alkali, thereby completing the present invention. .
　すなわち本発明は以下の通りである。
＜１＞
　生ガラスと、硝酸カリウムを含む無機塩とを接触させることによって、前記生ガラス中のＮａイオンと前記無機塩中のＫイオンとをイオン交換する工程を含むガラス基材の製造方法であって、
　前記無機塩はＫ２ＣＯ３、Ｎａ２ＣＯ３、ＫＨＣＯ３、ＮａＨＣＯ３、Ｋ３ＰＯ４、Ｎａ３ＰＯ４、Ｋ２ＳＯ４、Ｎａ２ＳＯ４、ＫＯＨ及びＮａＯＨからなる群より選ばれる少なくとも一種の塩を含み、Ｋ／Ｎａ比率が質量比で１以上１５以下であり、かつ
　前記イオン交換する工程の後にガラスを洗浄する工程、
　前記洗浄する工程の後にガラスを酸処理する工程、及び
　前記酸処理する工程の後にガラスをアルカリ処理する工程を含む、ガラス基材の製造方法。
＜２＞
　前記酸処理する工程の後に、ガラスを洗浄する工程を有することを特徴とする前記＜１＞記載のガラス基材の製造方法。
＜３＞
　前記アルカリ処理する工程の後に、ガラスを洗浄する工程を有することを特徴とする前記＜１＞記載のガラス基材の製造方法。
＜４＞
　生ガラスと、無機塩とを接触させることによって、前記生ガラス中のＮａイオンと前記無機塩中のＫイオンとをイオン交換する工程を含むガラス基材の製造方法であって、
　前記無機塩は、Ｋ／Ｎａ比率が質量比で１以上１５以下であり、かつ
　前記イオン交換する工程の後にガラスを洗浄する工程、
　前記洗浄する工程の後にガラスを酸処理する工程、及び
　前記酸処理する工程の後にガラスをアルカリ処理する工程を含む、ガラス基材の製造方法。
＜５＞
　前記無機塩は、硝酸カリウムを含む前記＜４＞記載のガラス基材の製造方法。
＜６＞
　前記酸処理する工程は、ｐＨ７未満である溶液を用いることを特徴とする前記＜１＞または＜４＞記載のガラス基材の製造方法。
＜７＞
　前記ｐＨ７未満である溶液は弱酸であることを特徴とする前記＜６＞記載のガラス基材の製造方法。
＜８＞
　前記ｐＨ７未満である溶液は強酸であることを特徴とする前記＜６＞記載のガラス基材の製造方法。
＜９＞
　前記酸処理する工程は、１００℃以下の温度でおこなうことを特徴とする前記＜１＞または＜４＞記載のガラス基材の製造方法。
＜１０＞
　前記酸処理する工程をおこなう時間は、１０秒～５時間であることを特徴とする前記＜１＞または＜４＞記載のガラス基材の製造方法。
＜１１＞
　前記アルカリ処理する工程は、ｐＨ７超過の溶液を用いることを特徴とする前記＜１＞または＜４＞記載のガラス基材の製造方法。
＜１２＞
　前記ｐＨ７超過の溶液は弱塩基であることを特徴とする前記＜１１＞記載のガラス基材の製造方法。
＜１３＞
　前記ｐＨ７超過の溶液は強塩基であることを特徴とする前記＜１１＞記載のガラス基材の製造方法。
＜１４＞
　前記アルカリ処理する工程は、０℃以上１００℃以下の温度でおこなうことを特徴とする前記＜１＞または＜４＞記載のガラス基材の製造方法。
＜１５＞
　前記アルカリ処理する工程をおこなう時間は、１０秒～５時間であることを特徴とする前記＜１＞または＜４＞記載のガラス基材の製造方法。 That is, the present invention is as follows.
<1>
A method for producing a glass substrate, comprising a step of ion-exchanging Na ions in the raw glass and K ions in the inorganic salt by contacting the raw glass with an inorganic salt containing potassium nitrate,
The inorganic salt is at least selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 , NaHCO 3 , K 3 PO 4 , Na 3 PO 4 , K 2 SO 4 , Na 2 SO 4 , KOH and NaOH. A step of containing a kind of salt, wherein the K / Na ratio is 1 to 15 in terms of mass ratio, and the glass is washed after the ion exchange step;
A method for producing a glass substrate, comprising: a step of acid-treating glass after the washing step; and a step of alkali-treating glass after the step of acid treatment.
<2>
The method for producing a glass substrate according to <1>, further comprising a step of washing glass after the acid treatment step.
<3>
The method for producing a glass substrate according to <1>, further comprising a step of washing glass after the alkali treatment step.
<4>
A method for producing a glass substrate, comprising a step of ion-exchanging Na ions in the raw glass and K ions in the inorganic salt by bringing the raw glass into contact with an inorganic salt,
The inorganic salt has a K / Na ratio of 1 to 15 in terms of mass ratio, and the step of washing the glass after the ion exchange step;
A method for producing a glass substrate, comprising: a step of acid-treating glass after the washing step; and a step of alkali-treating glass after the step of acid treatment.
<5>
The said inorganic salt is a manufacturing method of the glass base material of the said <4> description containing potassium nitrate.
<6>
The method for producing a glass substrate according to <1> or <4>, wherein the acid treatment step uses a solution having a pH of less than 7.
<7>
The method for producing a glass substrate according to <6>, wherein the solution having a pH of less than 7 is a weak acid.
<8>
The method for producing a glass substrate according to <6>, wherein the solution having a pH of less than 7 is a strong acid.
<9>
The method for producing a glass substrate according to <1> or <4>, wherein the acid-treating step is performed at a temperature of 100 ° C. or lower.
<10>
The method for producing a glass substrate according to <1> or <4>, wherein the time for performing the acid treatment is 10 seconds to 5 hours.
<11>
The method for producing a glass substrate according to <1> or <4>, wherein the alkali treatment step uses a solution having a pH exceeding 7.
<12>
The method for producing a glass substrate according to <11>, wherein the solution having a pH exceeding 7 is a weak base.
<13>
The method for producing a glass substrate according to <11>, wherein the solution having a pH exceeding 7 is a strong base.
<14>
The method for producing a glass substrate according to <1> or <4>, wherein the alkali treatment step is performed at a temperature of 0 ° C. or higher and 100 ° C. or lower.
<15>
The method for producing a glass substrate according to <1> or <4>, wherein the time for performing the alkali treatment step is 10 seconds to 5 hours.
　本発明の製造方法によれば、生ガラスよりも面強度が高いガラス基材を得ることができる。
　また本発明の製造方法によれば、圧縮応力層を有するが、最表面の圧縮応力値（ＣＳ）が低いガラス基材が得られる。このガラス基材は圧縮応力層を有するので、ガラス表面にクラックが発生しにくく扱い傷を抑制することができる。さらに、後の加工処理時にガラスが割れることが抑制され、扱い傷の発生を抑制しつつ、その後の処理を円滑に行なうことができる。また、最表面の圧縮応力値（ＣＳ）が低いので、内部引張応力（ＣＴ）を低く抑えることができるため、切断等の加工が容易である。 According to the production method of the present invention, a glass substrate having higher surface strength than raw glass can be obtained.
Moreover, according to the manufacturing method of this invention, although it has a compressive-stress layer, the glass base material with a low compressive-stress value (CS) of the outermost surface is obtained. Since this glass substrate has a compressive stress layer, it is difficult for cracks to occur on the glass surface, and handling flaws can be suppressed. Furthermore, the glass can be prevented from breaking during subsequent processing, and subsequent processing can be performed smoothly while suppressing the occurrence of handling flaws. In addition, since the compressive stress value (CS) on the outermost surface is low, the internal tensile stress (CT) can be kept low, so that processing such as cutting is easy.
図１は、ボールオンリング試験の方法を説明するための概略図である。FIG. 1 is a schematic diagram for explaining a ball-on-ring test method.
　以下、本発明を詳細に説明するが、本発明は以下の実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲において、任意に変形して実施することができる。 Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified without departing from the gist of the present invention.
　ここで、本明細書において“質量％”と“重量％”とは同義である。 Here, “mass%” and “wt%” are synonymous in this specification.
　また、本明細書において、「生ガラス（ｒａｗ　ｇｌａｓｓ）」とは、表面にイオン交換による圧縮応力層を有さないガラスである。「ガラス基材（ｂａｓｅ　ｇｌａｓｓ）」とは、生ガラスに、イオン交換処理、酸処理、アルカリ処理を行ったものである。このガラス基材は、表面にイオン交換された圧縮応力層を有し且つ、最表面の圧縮応力値（ＣＳ）が低いことを特徴とする。最表面の圧縮応力値（ＣＳ）が低いので、内部引張応力（ＣＴ）を低く抑えることができ、切断等の加工が容易である。また、「化学強化ガラス」とは、生ガラスまたはガラス基材に化学強化処理を施したものをいう。この化学強化ガラスは、表面にイオン交換された圧縮応力層を有し且つ、最表面の圧縮応力値（ＣＳ）が高いことを特徴とする。最表面の圧縮応力値（ＣＳ）が高いため、内部引張応力（ＣＴ）も高くなり、切断等の加工が容易ではない。 In addition, in this specification, “raw glass” is glass that does not have a compressive stress layer due to ion exchange on the surface. “Glass substrate” is obtained by subjecting raw glass to ion exchange treatment, acid treatment, and alkali treatment. This glass substrate has a compressive stress layer ion-exchanged on the surface, and has a low compressive stress value (CS) on the outermost surface. Since the compressive stress value (CS) on the outermost surface is low, the internal tensile stress (CT) can be kept low, and processing such as cutting is easy. The “chemically tempered glass” refers to a raw glass or a glass substrate that has been subjected to a chemical tempering treatment. This chemically strengthened glass has a compressive stress layer ion-exchanged on the surface, and has a high compressive stress value (CS) on the outermost surface. Since the compressive stress value (CS) on the outermost surface is high, the internal tensile stress (CT) is also high, and processing such as cutting is not easy.
＜ガラス基材の製造方法＞
　本発明に係るガラス基材を製造する方法の一態様を以下に説明するが、本発明はこれに限定されない。 <Method for producing glass substrate>
Although one aspect | mode of the method to manufacture the glass base material which concerns on this invention is demonstrated below, this invention is not limited to this.
（ガラス組成）
　本発明で使用されるガラスはナトリウムを含んでいればよく、成形、化学強化処理による強化が可能な組成を有するものである限り、種々の組成のものを使用することができる。具体的には、例えば、アルミノシリケートガラス、ソーダライムガラス、ボロシリケートガラス、鉛ガラス、アルカリバリウムガラス、アルミノボロシリケートガラス等が挙げられる。 (Glass composition)
The glass used in the present invention only needs to contain sodium, and glass having various compositions can be used as long as it has a composition that can be strengthened by molding and chemical strengthening treatment. Specific examples include aluminosilicate glass, soda lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass.
　生ガラスの製造方法は特に限定されず、所望のガラス原料を連続溶融炉に投入し、ガラス原料を好ましくは１５００～１６００℃で加熱溶融し、清澄した後、成形装置に供給した上で溶融ガラスを成形し、徐冷することにより製造することができる。 The production method of raw glass is not particularly limited, and a desired glass raw material is put into a continuous melting furnace, and the glass raw material is heated and melted preferably at 1500 to 1600 ° C., clarified, and then supplied to a molding apparatus. Can be produced by forming and slowly cooling.
　なお、生ガラスの成形には種々の方法を採用することができる。例えば、ダウンドロー法（例えば、オーバーフローダウンドロー法、スロットダウン法およびリドロー法等）、フロート法、ロールアウト法およびプレス法等の様々な成形方法を採用することができる。 It should be noted that various methods can be employed for forming raw glass. For example, various forming methods such as a down draw method (for example, an overflow down draw method, a slot down method and a redraw method), a float method, a roll-out method, and a press method can be employed.
　生ガラスの厚みは、特に制限されるものではないが、イオン交換処理や化学強化処理を効果的に行うために、通常５ｍｍ以下であることが好ましく、３ｍｍ以下であることがより好ましい。 The thickness of the raw glass is not particularly limited, but is usually preferably 5 mm or less and more preferably 3 mm or less in order to effectively perform the ion exchange treatment and the chemical strengthening treatment.
　また、本発明で使用されるガラスの形状は特に限定されない。例えば、均一な板厚を有する平板形状、表面と裏面のうち少なくとも一方に曲面を有する形状および屈曲部等を有する立体的な形状等の様々な形状のガラスを採用することができる。 Further, the shape of the glass used in the present invention is not particularly limited. For example, various shapes of glass such as a flat plate shape having a uniform plate thickness, a shape having a curved surface on at least one of the front surface and the back surface, and a three-dimensional shape having a bent portion can be employed.
　本発明の生ガラスの組成としては特に限定されないが、例えば、以下のガラスの組成が挙げられる。
（ｉ）モル％で表示した組成で、ＳｉＯ２を５０～８０％、Ａｌ２Ｏ３を２～２５％、Ｌｉ２Ｏを０～１０％、Ｎａ２Ｏを０～１８％、Ｋ２Ｏを０～１０％、ＭｇＯを０～１５％、ＣａＯを０～５％およびＺｒＯ２を０～５％を含むガラス
（ｉｉ）モル％で表示した組成が、ＳｉＯ２を５０～７４％、Ａｌ２Ｏ３を１～１０％、Ｎａ２Ｏを６～１４％、Ｋ２Ｏを３～１１％、ＭｇＯを２～１５％、ＣａＯを０～６％および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の含有量の合計が１２～２５％、ＭｇＯおよびＣａＯの含有量の合計が７～１５％であるガラス
（ｉｉｉ）モル％で表示した組成が、ＳｉＯ２を６８～８０％、Ａｌ２Ｏ３を４～１０％、Ｎａ２Ｏを５～１５％、Ｋ２Ｏを０～１％、ＭｇＯを４～１５％およびＺｒＯ２を０～１％含有するガラス
（ｉｖ）モル％で表示した組成が、ＳｉＯ２を６７～７５％、Ａｌ２Ｏ３を０～４％、Ｎａ２Ｏを７～１５％、Ｋ２Ｏを１～９％、ＭｇＯを６～１４％およびＺｒＯ２を０～１．５％含有し、ＳｉＯ２およびＡｌ２Ｏ３の含有量の合計が７１～７５％、Ｎａ２ＯおよびＫ２Ｏの含有量の合計が１２～２０％であり、ＣａＯを含有する場合その含有量が１％未満であるガラス Although it does not specifically limit as a composition of the raw glass of this invention, For example, the following glass compositions are mentioned.
(I) a composition that is displayed in mol%, the SiO 2 50 ~ 80%, the Al 2 O 3 2 ~ 25% , the Li 2 O 0 ~ 10%, a Na 2 O 0 ~ 18%, K 2 O Is represented by a glass (ii) mol% containing 0-10%, MgO 0-15%, CaO 0-5% and ZrO 2 0-5%, SiO 2 50-74%, Al 2 O 3 1-10%, Na 2 O 6-14%, K 2 O 3-11%, MgO 2-15%, CaO 0-6% and 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 is 12 to 25%, and the total content of MgO and CaO is 7 to 15%. a composition which is displayed at a certain glass (iii) mol%, a SiO 2 68 ~ 80%, the Al 2 O 3 4 ~ 10% , The a 2 O 5 ~ 15%, the K 2 O 0 to 1%, the MgO 4 ~ 15% and ZrO 2 is composition displaying a glass (iv) mole% containing 0 to 1%, a SiO 2 67 -75%, Al 2 O 3 0-4%, Na 2 O 7-15%, K 2 O 1-9%, MgO 6-14% and ZrO 2 0-1.5% The total content of SiO 2 and Al 2 O 3 is 71 to 75%, the total content of Na 2 O and K 2 O is 12 to 20%, and when CaO is contained, the content is 1% Glass that is less than
　本発明に係るガラス基材は、表面にイオン交換された圧縮応力層を有し且つ、最表面の圧縮応力値（ＣＳ）が低いことを特徴とする。イオン交換法では、ガラスの表面をイオン交換し、圧縮応力が残留する圧縮応力層を形成させる。具体的には、ガラス転移点以下の温度でイオン交換によりガラス表面のイオン半径が小さなアルカリ金属イオン（典型的には、Ｌｉイオン、Ｎａイオン）をイオン半径のより大きいアルカリイオン（典型的には、Ｌｉイオンに対してはＮａイオンまたはＫイオンであり、Ｎａイオンに対してはＫイオン）に置換する。これにより、ガラスの表面に圧縮応力が残留し、ガラスの強度が向上する。本発明に係るガラス基材の製造方法では、以下に示すように特定の無機塩と接触させることで、わずかにガラス表面がイオン交換され、圧縮応力層を有し、且つ、最表面の圧縮応力値（ＣＳ）が低いガラス基材を得ることができる。 The glass substrate according to the present invention has a compressive stress layer ion-exchanged on the surface, and has a low compressive stress value (CS) on the outermost surface. In the ion exchange method, the surface of glass is ion exchanged to form a compressive stress layer in which compressive stress remains. Specifically, alkali metal ions (typically Li ions and Na ions) having a small ion radius on the glass surface by ion exchange at temperatures below the glass transition point are converted into alkali ions (typically Li ions and Na ions) having a larger ion radius. , Li ions are Na ions or K ions, and Na ions are substituted with K ions). Thereby, compressive stress remains on the surface of the glass, and the strength of the glass is improved. In the method for producing a glass substrate according to the present invention, the glass surface is slightly ion-exchanged by contacting with a specific inorganic salt as shown below, and has a compressive stress layer, and the compressive stress on the outermost surface. A glass substrate having a low value (CS) can be obtained.
　本発明の製造方法においては、硝酸カリウム（ＫＮＯ３）を含み、Ｋ／Ｎａ比率が質量比で特定範囲である無機塩と、生ガラスとを接触させる。これによりガラス表面のＮａイオンと無機塩中のＫイオンとがイオン交換されることで高密度な圧縮応力層が形成される。前記無機塩は、さらに後述する特定の塩（融剤）を含むことが好ましい。
　無機塩に生ガラスを接触させる方法としては、ペースト状の無機塩を塗布する方法、無機塩の水溶液を生ガラスに噴射する方法、融点以上に加熱した溶融塩の塩浴に生ガラスを浸漬させる方法などが可能であるが、これらの中では、溶融塩に浸漬させる方法が望ましい。 In the production method of the present invention, an inorganic salt containing potassium nitrate (KNO 3 ) and having a K / Na ratio in a specific range by mass ratio is brought into contact with raw glass. Thereby, Na ions on the glass surface and K ions in the inorganic salt are ion-exchanged to form a high-density compressive stress layer. It is preferable that the inorganic salt further includes a specific salt (flux) described later.
As a method of bringing the raw glass into contact with the inorganic salt, a method of applying a paste-like inorganic salt, a method of spraying an aqueous solution of an inorganic salt onto the raw glass, or immersing the raw glass in a salt bath of a molten salt heated to a melting point or higher Although a method etc. are possible, Among these, the method of immersing in molten salt is desirable.
　無機塩としてはガラスの歪点（通常５００～６００℃）以下に融点を有するものが好ましく、硝酸カリウム（融点３３０℃）を含有する塩が好ましい。硝酸カリウムを含有することでガラスの歪点以下で溶融状態であり、かつ使用温度領域においてハンドリングが容易となる。無機塩における硝酸カリウムの含有量は５０質量％以上であることがより好ましい。 As the inorganic salt, those having a melting point below the glass strain point (usually 500 to 600 ° C.) are preferred, and salts containing potassium nitrate (melting point 330 ° C.) are preferred. By containing potassium nitrate, it is in a molten state below the strain point of the glass, and handling is easy in the operating temperature range. The content of potassium nitrate in the inorganic salt is more preferably 50% by mass or more.
　無機塩はさらに、Ｋ２ＣＯ３、Ｎａ２ＣＯ３、ＫＨＣＯ３、ＮａＨＣＯ３、Ｋ３ＰＯ４、Ｎａ３ＰＯ４、Ｋ２ＳＯ４、Ｎａ２ＳＯ４、ＫＯＨ及びＮａＯＨからなる群より選ばれる少なくとも一種の塩を含有することがより好ましい。中でもＫ２ＣＯ３、Ｎａ２ＣＯ３、ＫＨＣＯ３及びＮａＨＣＯ３からなる群より選ばれる少なくとも一種の塩を含有することがさらに好ましい。 The inorganic salt is further selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 , NaHCO 3 , K 3 PO 4 , Na 3 PO 4 , K 2 SO 4 , Na 2 SO 4 , KOH and NaOH. More preferably, it contains at least one salt. Among these, it is more preferable to contain at least one salt selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 and NaHCO 3 .
　上記塩（以下、「融剤」と称することもある。）は、Ｓｉ－Ｏ－Ｓｉ結合に代表されるガラスのネットワークを切断する性質を有する。ガラスのＳｉ－Ｏ間の共有結合が適度に切断されることで、後述する低密度層の形成を促進する。 The above-mentioned salt (hereinafter sometimes referred to as “flux”) has a property of cutting a glass network represented by Si—O—Si bonds. The formation of a low-density layer, which will be described later, is promoted by appropriately breaking the covalent bond between Si—O of the glass.
　なお、共有結合を切断する度合いはガラス組成や用いる塩（融剤）の種類、無機塩を接触させる温度、時間等の処理条件によっても異なるが、Ｓｉから伸びている４本の共有結合のうち、１～２本の結合が切れる程度の条件を選択することが好ましいものと考えられる。 The degree of breaking the covalent bond varies depending on the glass composition, the type of salt (flux) used, the temperature at which the inorganic salt is brought into contact, the processing conditions such as the time, and the like. It is considered preferable to select conditions that can break one or two bonds.
　融剤の添加量は、後述する低密度層除去量確保の点から０．１ｍｏｌ％以上が好ましく、０．５ｍｏｌ％以上がさらに好ましく、１ｍｏｌ％以上がより好ましく、２ｍｏｌ％以上が特に好ましい。また生産性の観点から各塩の飽和溶解度以下が好ましい。過剰に添加するとガラスの腐食につながるおそれがある。 The amount of the flux added is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, more preferably 1 mol% or more, and particularly preferably 2 mol% or more from the viewpoint of securing the removal amount of the low density layer described later. Further, from the viewpoint of productivity, the saturation solubility or less of each salt is preferable. Addition in excess may lead to glass corrosion.
　例えば融剤としてＫ２ＣＯ３を混合して用いる場合には、無機塩における融剤の含有量を０．１ｍｏｌ％以上とし、２４ｍｏｌ％以下が好ましく、１２ｍｏｌ％以下がより好ましく、８ｍｏｌ％以下が特に好ましい。また、ガラス接触温度を３５０～５００℃とすると、ガラス接触時間は１分～５０時間が好ましく、５分～４０時間がより好ましく、１０分～３０時間がさらに好ましい。また上限は１０時間がよりさらに好ましく、８時間がことさらに好ましく、４時間が特に好ましい。 For example, when K 2 CO 3 is mixed and used as a flux, the content of the flux in the inorganic salt is 0.1 mol% or more, preferably 24 mol% or less, more preferably 12 mol% or less, and more preferably 8 mol% or less. Particularly preferred. When the glass contact temperature is 350 to 500 ° C., the glass contact time is preferably 1 minute to 50 hours, more preferably 5 minutes to 40 hours, and even more preferably 10 minutes to 30 hours. The upper limit is more preferably 10 hours, more preferably 8 hours, and particularly preferably 4 hours.
　例えば融剤としてＮａ２ＣＯ３を混合して用いる場合には、無機塩における融剤の含有量を０．１ｍｏｌ％以上とし、２４ｍｏｌ％以下が好ましく、１２ｍｏｌ％以下がより好ましく、８ｍｏｌ％以下が特に好ましい。また、ガラス接触温度を３５０～５００℃とすると、ガラス接触時間は１分～５０時間が好ましく、５分～４０時間がより好ましく、１０分～３０時間がさらに好ましい。また上限は１０時間がよりさらに好ましく、８時間がことさらに好ましく、４時間が特に好ましいい。 For example, when Na 2 CO 3 is mixed and used as the flux, the content of the flux in the inorganic salt is 0.1 mol% or more, preferably 24 mol% or less, more preferably 12 mol% or less, and more preferably 8 mol% or less. Particularly preferred. When the glass contact temperature is 350 to 500 ° C., the glass contact time is preferably 1 minute to 50 hours, more preferably 5 minutes to 40 hours, and even more preferably 10 minutes to 30 hours. The upper limit is more preferably 10 hours, more preferably 8 hours, and particularly preferably 4 hours.
　本発明の製造方法において、上記無機塩は、Ｋ／Ｎａ比率が質量比で１以上１５以下、好ましくは２以上１２以下、より好ましくは２以上１０以下である。かかるＫ／Ｎａ質量比率の無機塩を生ガラスと接触させることで、イオン交換がわずかに起こるため、圧縮応力層を有しつつ、且つ、最表面の圧縮応力値（ＣＳ）が低いガラス基材を得ることができる。Ｋ／Ｎａ質量比率は、例えば無機塩にＮａＮＯ３、ＫＮＯ３、及び上記した融剤等を添加することによって調整することができる。 In the production method of the present invention, the inorganic salt has a K / Na ratio of 1 to 15 by mass, preferably 2 to 12 and more preferably 2 to 10. A glass substrate having a compressive stress layer and a low compressive stress value (CS) on the outermost surface because ion exchange occurs slightly by bringing the inorganic salt of K / Na mass ratio into contact with green glass. Can be obtained. The K / Na mass ratio can be adjusted, for example, by adding NaNO 3 , KNO 3 , the above-described flux and the like to the inorganic salt.
　無機塩は、上記の他に、本発明の効果を阻害しない範囲で他の化学種を含んでいてもよく、例えば、塩化ナトリウム、塩化カリウム、ホウ酸ナトリウム、ホウ酸カリウム等のアルカリ塩酸塩やアルカリホウ酸塩などが挙げられる。これらは単独で添加しても、複数種を組み合わせて添加してもよい。 In addition to the above, the inorganic salt may contain other chemical species as long as the effect of the present invention is not impaired. For example, alkali salts such as sodium chloride, potassium chloride, sodium borate, potassium borate, etc. An alkali borate etc. are mentioned. These may be added alone or in combination of two or more.
　以下、生ガラスを溶融塩に浸漬させる方法によりイオン交換を行う態様を例に、本発明の製造方法を説明する。 Hereinafter, the production method of the present invention will be described by taking as an example an embodiment in which ion exchange is performed by immersing raw glass in molten salt.
（溶融塩の製造１）
　溶融塩は下記に示す工程により製造することができる。
工程１ａ：硝酸カリウム溶融塩の調製
工程２ａ：硝酸カリウム溶融塩への融剤の添加 (Manufacture of molten salt 1)
The molten salt can be produced by the steps shown below.
Step 1a: Preparation of potassium nitrate molten salt Step 2a: Addition of flux to potassium nitrate molten salt
（工程１ａ－硝酸カリウム溶融塩の調製－）
　工程１ａでは、硝酸カリウムを含有する無機塩を容器に投入し、融点以上の温度に加熱して溶融することで、溶融塩を調製する。溶融は、硝酸カリウムの融点（３３０℃）と、沸点（５００℃）の範囲内の温度で行う。特に溶融温度を３５０～５００℃とすることが、ガラスに付与できる表面圧縮応力（ＣＳ）と圧縮応力層深さ（ＤＯＬ）のバランスおよび強化時間の点からより好ましく、３５０～４７０℃がさらに好ましい。 (Step 1a-Preparation of molten potassium nitrate salt)
In step 1a, an inorganic salt containing potassium nitrate is put into a container, and heated to a temperature equal to or higher than the melting point to be melted to prepare a molten salt. Melting is performed at a temperature within the range of the melting point (330 ° C.) and boiling point (500 ° C.) of potassium nitrate. In particular, the melting temperature is preferably 350 to 500 ° C. from the viewpoint of the balance between the surface compressive stress (CS) and the compressive stress layer depth (DOL) that can be applied to the glass and the strengthening time, and more preferably 350 to 470 ° C. .
　無機塩を溶融する容器は、金属、石英、セラミックスなどを用いることができる。中でも、耐久性の観点から金属材質が望ましく、耐食性の観点からはステンレススチール（ＳＵＳ）材質が好ましい。 As the container for melting the inorganic salt, metal, quartz, ceramics, or the like can be used. Among these, a metal material is desirable from the viewpoint of durability, and a stainless steel (SUS) material is preferable from the viewpoint of corrosion resistance.
（工程２ａ－硝酸カリウム溶融塩への融剤の添加－）
　工程２ａでは、工程１ａで調製した硝酸カリウム溶融塩中に、先述した融剤や、Ｋ／Ｎａ比率を調整するための化学種を添加し、温度を一定範囲に保ちながら、攪拌翼などにより、全体が均一になるように混合する。複数の融剤を併用する場合、添加順序は限定されず、同時に添加してもよい。
　温度は、硝酸カリウムの融点以上、すなわち３３０℃以上が好ましく、３５０～５００℃がより好ましい。また、攪拌時間は１分～５０時間が好ましく、１０分～３０時間がより好ましい。また上限は１０時間がよりさらに好ましく、２時間が特に好ましい。 (Step 2a-Addition of flux to potassium nitrate molten salt-)
In step 2a, the above-mentioned flux and chemical species for adjusting the K / Na ratio are added to the potassium nitrate molten salt prepared in step 1a, and the entire temperature is maintained with a stirring blade while maintaining the temperature within a certain range. Mix until uniform. When using a plurality of fluxes in combination, the order of addition is not limited, and they may be added simultaneously.
The temperature is preferably equal to or higher than the melting point of potassium nitrate, that is, 330 ° C. or higher, and more preferably 350 to 500 ° C. The stirring time is preferably 1 minute to 50 hours, more preferably 10 minutes to 30 hours. The upper limit is more preferably 10 hours, and particularly preferably 2 hours.
（溶融塩の製造２）
　上記の溶融塩の製造１では、硝酸カリウムを含有する溶融塩の調製後に融剤を加える方法を例示したが、溶融塩はまた、下記に示す工程により製造することができる。
工程１ｂ：硝酸カリウムを含有する無機塩と融剤の混合
工程２ｂ：硝酸カリウムを含有する無機塩と融剤との混合塩の溶融 (Manufacture of molten salt 2)
In the production of the molten salt 1 described above, the method of adding the flux after preparation of the molten salt containing potassium nitrate is exemplified, but the molten salt can also be produced by the steps shown below.
Step 1b: Mixing of inorganic salt containing potassium nitrate and flux Step 2b: Melting of mixed salt of inorganic salt containing potassium nitrate and flux
（工程１ｂ―硝酸カリウムを含有する無機塩と融剤の混合―）
　工程１ｂでは、硝酸カリウムを含有する無機塩と融剤とを容器に投入して、攪拌翼などにより混合する。複数の融剤を併用する場合、添加順序は限定されず、同時に添加してもよい。容器は上記工程１ａで用いるものと同様のものを用いることができる。 (Step 1b-Mixing of inorganic salt containing potassium nitrate and flux-)
In step 1b, an inorganic salt containing potassium nitrate and a flux are put into a container and mixed with a stirring blade or the like. When using a plurality of fluxes in combination, the order of addition is not limited, and they may be added simultaneously. The same container as that used in the above step 1a can be used.
（工程２ｂ―硝酸カリウムを含有する無機塩と融剤との混合塩の溶融―）
　工程２ｂでは、工程１ｂにより得られる混合塩を加熱して溶融する。溶融は、硝酸カリウムの融点（３３０℃）と、沸点（５００℃）の範囲内の温度で行う。特に溶融温度を３５０～４７０℃とすることが、ガラスに付与できる表面圧縮応力（ＣＳ）と圧縮応力層深さ（ＤＯＬ）のバランスおよび強化時間の点からより好ましい。攪拌時間は１分～１０時間が好ましく、１０分～２時間がより好ましい。 (Step 2b-Melting of mixed salt of inorganic salt containing potassium nitrate and flux-)
In step 2b, the mixed salt obtained in step 1b is heated and melted. Melting is performed at a temperature within the range of the melting point (330 ° C.) and boiling point (500 ° C.) of potassium nitrate. In particular, the melting temperature is preferably 350 to 470 ° C. from the viewpoint of the balance between the surface compressive stress (CS) and the compressive stress layer depth (DOL) that can be applied to the glass, and the strengthening time. The stirring time is preferably 1 minute to 10 hours, and more preferably 10 minutes to 2 hours.
　上記工程１ａ及び工程２ａ又は工程１ｂ及び工程２ｂを経て得られる溶融塩において、融剤の添加により析出物が発生する場合には、生ガラスのイオン交換処理を行う前に、当該析出物が容器の底に沈殿するまで静置する。この析出物には、飽和溶解度を超えた分の融剤や、融剤のカチオンが溶融塩中で交換された塩が含まれる。 In the molten salt obtained through the step 1a and the step 2a or the step 1b and the step 2b, when a precipitate is generated by the addition of a flux, the precipitate is a container before the ion exchange treatment of raw glass. Let it settle until it settles at the bottom. This precipitate includes a flux exceeding the saturation solubility and a salt in which the cations of the flux are exchanged in the molten salt.
（イオン交換処理）
　次に、調製した溶融塩を用いてイオン交換処理を行う。イオン交換処理は、生ガラスを溶融塩に浸漬し、生ガラス中の金属イオン（Ｎａイオン）を、溶融塩中のイオン半径の大きな金属イオン（Ｋイオン）と置換することで行われる。このイオン交換によってガラス表面の組成を変化させ、ガラス表面が高密度化した圧縮応力層を形成することができる。このガラス表面の高密度化によって圧縮応力が発生することから、生ガラスを強化することができる。 (Ion exchange treatment)
Next, an ion exchange treatment is performed using the prepared molten salt. The ion exchange treatment is performed by immersing raw glass in a molten salt and replacing metal ions (Na ions) in the raw glass with metal ions (K ions) having a large ion radius in the molten salt. By this ion exchange, the composition of the glass surface can be changed to form a compressive stress layer in which the glass surface has a high density. Since the compressive stress is generated by increasing the density of the glass surface, the raw glass can be strengthened.
　なお実際には、ガラスの密度は、ガラスの中心に存在する中間層（バルク）の外縁から圧縮応力層表面に向かって徐々に高密度化してくるため、中間層と圧縮応力層との間には、密度が急激に変化する明確な境界はない。ここで中間層とは、ガラス中心部に存在し、圧縮応力層に挟まれる層を表す。この中間層は圧縮応力層とは異なり、イオン交換がされていない層である。 Actually, the density of the glass gradually increases from the outer edge of the intermediate layer (bulk) present at the center of the glass toward the surface of the compressive stress layer, so that the gap between the intermediate layer and the compressive stress layer is There is no clear boundary where the density changes rapidly. Here, the intermediate layer is a layer present in the center of the glass and sandwiched between the compressive stress layers. Unlike the compressive stress layer, this intermediate layer is a layer that is not ion-exchanged.
　本発明におけるイオン交換処理は、具体的には、下記工程３により行うことができる。
工程３：生ガラスのイオン交換処理 Specifically, the ion exchange treatment in the present invention can be performed by the following step 3.
Process 3: Raw glass ion exchange treatment
（工程３－生ガラスのイオン交換処理－）
　工程３では、生ガラスを予熱し、上記工程１ａ及び工程２ａ又は工程１ｂ及び工程２ｂで調製した溶融塩を、化学強化を行う温度に調整する。次いで予熱した生ガラスを溶融塩中に所定の時間浸漬したのち、溶融塩中から引き上げ、放冷する。 (Process 3-Ion exchange treatment of raw glass-)
In step 3, raw glass is preheated, and the molten salt prepared in steps 1a and 2a or steps 1b and 2b is adjusted to a temperature at which chemical strengthening is performed. Next, after the preheated raw glass is immersed in the molten salt for a predetermined time, it is pulled up from the molten salt and allowed to cool.
　生ガラスの予熱温度は、溶融塩に浸漬する温度に依存するが、一般に１００℃以上であることが好ましい。 The preheating temperature of raw glass depends on the temperature immersed in the molten salt, but is generally preferably 100 ° C. or higher.
　イオン交換処理温度は、硝酸カリウムの融点以上、すなわち３３０℃以上が好ましい。また、生ガラスの歪点（通常５００～６００℃）以下が好ましく、歪み点よりマイナス５０℃以下がより好ましい。特に溶融温度を３５０～５００℃とすることが、ガラスに付与できる表面圧縮応力（ＣＳ）と圧縮応力深さ（ＤＯＬ）のバランスおよび強化時間の点からより好ましい。 The ion exchange treatment temperature is preferably higher than the melting point of potassium nitrate, that is, 330 ° C. or higher. Moreover, the strain point (generally 500 to 600 ° C.) or less of raw glass is preferable, and minus 50 ° C. or less is more preferable than the strain point. In particular, the melting temperature is preferably 350 to 500 ° C. from the viewpoint of the balance between the surface compressive stress (CS) and the compressive stress depth (DOL) that can be applied to the glass, and the strengthening time.
　生ガラスの溶融塩への浸漬時間は１分～５０時間が好ましく、５分～４０時間がより好ましく、１０分～３０時間がさらに好ましい。また上限は１０時間がよりさらに好ましく、８時間がことさらに好ましく、４時間が特に好ましい。かかる範囲にあれば、強度と圧縮応力層の深さのバランスに優れたガラス基材を得ることができる。 The immersion time of raw glass in the molten salt is preferably 1 minute to 50 hours, more preferably 5 minutes to 40 hours, and even more preferably 10 minutes to 30 hours. The upper limit is more preferably 10 hours, more preferably 8 hours, and particularly preferably 4 hours. If it exists in this range, the glass base material excellent in the balance of an intensity | strength and the depth of a compressive-stress layer can be obtained.
　本発明の製造方法では続いて、イオン交換処理後に下記工程を行う。
工程４：ガラスの洗浄
工程５：工程４を経た後のガラスの酸処理
　上記工程５まで経た時点で、ガラスの表面には圧縮応力層の表層が変質した、具体的には低密度化された、低密度層をさらに有することとなる。低密度層とは、圧縮応力層の最表面からＮａやＫが抜け（リーチングし）、代わりにＨが入り込む（置換する）ことによって形成される。
　以下、工程４及び工程５について詳述する。 In the production method of the present invention, subsequently, the following steps are performed after the ion exchange treatment.
Step 4: Glass cleaning Step 5: Acid treatment of glass after Step 4 At the time of going to Step 5, the surface layer of the compressive stress layer was altered on the surface of the glass, specifically, the density was reduced. It will further have a low density layer. The low density layer is formed by Na (leaching) from the outermost surface of the compressive stress layer (leaching) and H entering (replacement) instead.
Hereinafter, step 4 and step 5 will be described in detail.
（工程４－ガラスの洗浄－）
　工程４では工水、イオン交換水等を用いてガラスの洗浄を行う。中でもイオン交換水が好ましい。洗浄の条件は用いる洗浄液によっても異なるが、イオン交換水を用いる場合には０～１００℃で洗浄することが付着した塩を完全に除去させる点から好ましい。 (Step 4-Glass cleaning-)
In step 4, glass is cleaned using industrial water, ion exchange water, or the like. Of these, ion-exchanged water is preferred. The washing conditions vary depending on the washing solution used, but when ion-exchanged water is used, washing at 0 to 100 ° C. is preferable from the viewpoint of completely removing the attached salt.
（工程５－酸処理－）
　工程５では、工程４で洗浄したガラスに対して、さらに酸処理を行う。
　ガラスの酸処理とは、酸性の溶液中に、ガラスを浸漬させることによって行い、これによりガラス表面のＮａ及び／又はＫをＨに置換することができる。
　溶液は酸性であれば特に制限されずｐＨ７未満であればよく、用いられる酸が弱酸であっても強酸であってもよい。具体的には塩酸、硝酸、硫酸、リン酸、酢酸、シュウ酸、炭酸及びクエン酸等の酸が好ましい。これらの酸は単独で用いても、複数を組み合わせて用いてもよい。 (Step 5-Acid treatment-)
In step 5, the glass cleaned in step 4 is further subjected to acid treatment.
The acid treatment of the glass is performed by immersing the glass in an acidic solution, whereby Na and / or K on the glass surface can be replaced with H.
The solution is not particularly limited as long as it is acidic, and may be less than pH 7. The acid used may be a weak acid or a strong acid. Specifically, acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid, carbonic acid and citric acid are preferred. These acids may be used alone or in combination.
　酸処理を行う温度は、用いる酸の種類や濃度、時間によっても異なるが、１００℃以下で行うことが好ましい。
　酸処理を行う時間は、用いる酸の種類や濃度、温度によっても異なるものの、１０秒～５時間が生産性の点から好ましく、１分～２時間がより好ましい。
　酸処理を行う溶液の濃度は、用いる酸の種類や時間、温度によって異なるものの、容器腐食の懸念が少ない濃度が好ましく、具体的には０．０５重量％～２０重量％が好ましい。 The temperature at which the acid treatment is performed varies depending on the type, concentration, and time of the acid used, but is preferably 100 ° C. or less.
The time for the acid treatment varies depending on the type, concentration and temperature of the acid used, but is preferably 10 seconds to 5 hours from the viewpoint of productivity, and more preferably 1 minute to 2 hours.
The concentration of the solution used for the acid treatment varies depending on the type of acid used, the time, and the temperature, but is preferably a concentration at which there is little concern about container corrosion, specifically 0.05 to 20% by weight.
　低密度層は、後述するアルカリ処理により除去されるため、低密度層が厚いほどガラスの表面が除去されやすい。したがって低密度層の厚みはガラスの表面除去量の観点から５ｎｍ以上が好ましく、２０ｎｍ以上がより好ましい。低密度層の厚みはイオン交換処理工程における融剤濃度、温度、時間等により制御することができる。 Since the low density layer is removed by an alkali treatment described later, the thicker the low density layer, the easier the surface of the glass is removed. Therefore, the thickness of the low density layer is preferably 5 nm or more, more preferably 20 nm or more from the viewpoint of the amount of glass surface removed. The thickness of the low density layer can be controlled by the flux concentration, temperature, time, etc. in the ion exchange treatment step.
　低密度層の密度はガラスの表面除去性の観点から、イオン交換された圧縮応力層よりも深い領域（バルク）の密度に比べて低いことが好ましい。 The density of the low-density layer is preferably lower than the density of the region (bulk) deeper than the ion-exchanged compressive stress layer from the viewpoint of glass surface removability.
　低密度層の厚みはＸ線反射率法（Ｘ－ｒａｙ－Ｒｅｆｌｅｃｔｏｍｅｔｒｙ：ＸＲＲ）によって測定した周期（Δθ）から求めることができる。
　低密度層の密度はＸＲＲによって測定した臨界角（θｃ）により求めることができる。
　なお、簡易的には走査型電子顕微鏡（ＳＥＭ）でガラスの断面を観察することによって、低密度層の形成と層の厚みを確認することも可能である。 The thickness of the low density layer can be determined from the period (Δθ) measured by the X-ray reflectivity method (X-ray-Reflectometry: XRR).
The density of the low density layer can be determined from the critical angle (θc) measured by XRR.
In addition, it is also possible to confirm the formation of the low density layer and the thickness of the layer by simply observing a cross section of the glass with a scanning electron microscope (SEM).
　本発明の製造方法では続いて、酸処理後に下記工程を行う。
工程６：アルカリ処理
　上記工程６により、工程５までに形成された低密度層の一部又は全部を除去することができる。
　以下、工程６について詳述する。 In the production method of the present invention, the following steps are subsequently performed after the acid treatment.
Step 6: Alkali Treatment According to the above step 6, part or all of the low density layer formed up to step 5 can be removed.
Hereinafter, step 6 will be described in detail.
（工程６－アルカリ処理－）
　工程６では、工程５で酸処理したガラスに対して、さらにアルカリ処理を行う。
　アルカリ処理とは、塩基性の溶液中に、ガラスを浸漬させることによって行い、これにより低密度層の一部又は全部を除去することができる。
　溶液は塩基性であれば特に制限されずｐＨ７超過であればよく、弱塩基を用いても強塩基を用いてもよい。具体的には水酸化ナトリウム、水酸化カリウム、炭酸カリウム、炭酸ナトリウム等の塩基が好ましい。これらの塩基は単独で用いても、複数を組み合わせて用いてもよい。 (Step 6-alkali treatment)
In step 6, the glass treated with acid in step 5 is further subjected to alkali treatment.
The alkali treatment is performed by immersing glass in a basic solution, whereby a part or all of the low density layer can be removed.
The solution is not particularly limited as long as it is basic, and may have a pH exceeding 7, and a weak base or a strong base may be used. Specifically, bases such as sodium hydroxide, potassium hydroxide, potassium carbonate and sodium carbonate are preferred. These bases may be used alone or in combination.
　アルカリ処理を行う温度は、用いる塩基の種類や濃度、時間によっても異なるが、０～１００℃が好ましく、１０～８０℃がより好ましく、２０～６０℃が特に好ましい。かかる温度範囲であればガラスが腐食するおそれがなく好ましい。
　アルカリ処理を行う時間は、用いる塩基の種類や濃度、温度によっても異なるものの、１０秒間～５時間が生産性の点から好ましく、１分間～２時間がより好ましい。
　アルカリ処理を行う溶液の濃度は、用いる塩基の種類や時間、温度によって異なるものの、ガラスの表面除去性の観点から０．１重量％～２０重量％が好ましい。 The temperature for the alkali treatment varies depending on the type, concentration and time of the base used, but is preferably 0 to 100 ° C, more preferably 10 to 80 ° C, and particularly preferably 20 to 60 ° C. If it is this temperature range, there is no possibility that glass will corrode and it is preferable.
Although the alkali treatment time varies depending on the type, concentration and temperature of the base used, it is preferably 10 seconds to 5 hours from the viewpoint of productivity, and more preferably 1 minute to 2 hours.
The concentration of the solution used for the alkali treatment varies depending on the type of base used, the time, and the temperature, but is preferably from 0.1% by weight to 20% by weight from the viewpoint of glass surface removability.
　上記アルカリ処理により、Ｈが侵入した低密度層の一部又は全部が除去され、面強度が向上したガラス基材を得ることができる。さらに、低密度層が除去されることでガラス表面に存在していた傷も同時に除去されるので、この点も強度向上に寄与すると考えられる。 By the alkali treatment, a part or all of the low density layer into which H has penetrated is removed, and a glass substrate with improved surface strength can be obtained. Further, since the scratches existing on the glass surface are also removed at the same time by removing the low density layer, this point is also considered to contribute to the strength improvement.
　上記酸処理工程５およびアルカリ処理工程６の間や、アルカリ処理工程６の終了後に、工程４と同様の洗浄工程を有することが好ましい。 It is preferable to have a cleaning step similar to step 4 between the acid treatment step 5 and the alkali treatment step 6 or after completion of the alkali treatment step 6.
　本発明の製造方法によれば取り扱う薬液の安全性が高いため特別な設備を必要としない。したがって、面強度が格段に向上したガラス基材を安全かつ効率的に得ることができる。 According to the production method of the present invention, no special equipment is required because the chemicals to be handled are highly safe. Therefore, it is possible to safely and efficiently obtain a glass substrate having a significantly improved surface strength.
　なお、除去される低密度層の量は、アルカリ処理の条件による。低密度層は一部が除去され一部が残存していてもよい。強度向上の観点からは、低密度層の全部が取り除かれずとも効果を得ることができるが、ガラスの透過率を安定的に確保する観点から低密度層の全部を取り除くことが好ましい。 Note that the amount of the low density layer to be removed depends on the conditions of the alkali treatment. A part of the low-density layer may be removed and a part may remain. From the viewpoint of improving the strength, the effect can be obtained without removing all of the low density layer, but it is preferable to remove all of the low density layer from the viewpoint of stably securing the transmittance of the glass.
（ガラス基材の圧縮応力値（ＣＳ）、圧縮応力層深さ（ＤＯＬ））
　本発明の製造方法によれば、ガラス表面がイオン交換され、圧縮応力層を有し、且つ、最表面の圧縮応力値（ＣＳ）が低いガラス基材を得ることができる。
　本発明のガラス基材の最表面の圧縮応力値（ＣＳ）としては１００～６５０（ＭＰａ）が好ましい。ガラス基材の圧縮応力層深さ（ＤＯＬ）としては２０～１５０（μｍ）が好ましく、２０～４０（μｍ）がさらに好ましい。 (Compressive stress value (CS) of glass substrate, depth of compressive stress layer (DOL))
According to the production method of the present invention, it is possible to obtain a glass substrate whose glass surface is ion-exchanged, has a compressive stress layer, and has a low outermost compressive stress value (CS).
The compressive stress value (CS) of the outermost surface of the glass substrate of the present invention is preferably 100 to 650 (MPa). The compressive stress layer depth (DOL) of the glass substrate is preferably 20 to 150 (μm), more preferably 20 to 40 (μm).
（面強度）
　本発明のガラス基材の強度（面強度）は、ボールオンリング試験により評価することができる。
（ボールオンリング試験）
　ガラス基材を直径３０ｍｍ、接触部が曲率半径２．５ｍｍの丸みを持つステンレスからなるリング上に配置し、該ガラス板に直径１０ｍｍの鋼からなる球体を接触させた状態で、該球体を静的荷重条件下で該リングの中心に荷重するボールオンリング（Ｂａｌｌ　ｏｎ　Ｒｉｎｇ；ＢＯＲ）試験により測定したＢＯＲ面強度Ｆ（Ｎ）で評価する。
　本発明のガラス基材は、Ｆ≧１８００×ｔ２であることが好ましく、Ｆ≧２０００×ｔ２であることがより好ましい［式中、Ｆはボールオンリング試験により測定したＢＯＲ面強度（Ｎ）であり、ｔはガラス基板の板厚（ｍｍ）である。］。ＢＯＲ面強度Ｆ（Ｎ）がかかる範囲であることにより、薄板化した場合にも優れた強度を示す。 (Area strength)
The strength (surface strength) of the glass substrate of the present invention can be evaluated by a ball-on-ring test.
(Ball-on-ring test)
A glass substrate is placed on a ring made of stainless steel having a diameter of 30 mm and a contact portion having a radius of curvature of 2.5 mm, and the sphere is statically kept in contact with a glass sphere made of steel having a diameter of 10 mm. The BOR surface strength F (N) measured by a ball-on-ring (BOR) test in which the load is applied to the center of the ring under dynamic load conditions is evaluated.
The glass substrate of the present invention preferably has F ≧ 1800 × t 2 and more preferably F ≧ 2000 × t 2 [wherein F is the BOR surface strength (N T is the thickness (mm) of the glass substrate. ]. When the BOR surface strength F (N) is within this range, excellent strength is exhibited even when the plate is thinned.
　図１に、本発明で用いたボールオンリング試験を説明するための概略図を示す。ボールオンリング（Ｂａｌｌ　ｏｎ　Ｒｉｎｇ；ＢＯＲ）試験では、ガラス板１を水平に載置した状態で、ＳＵＳ３０４製の加圧治具２（焼入れ鋼、直径１０ｍｍ、鏡面仕上げ）を用いてガラス板１を加圧し、ガラス板１の面強度を測定する。 FIG. 1 shows a schematic diagram for explaining the ball-on-ring test used in the present invention. In the ball on ring (BOR) test, the glass plate 1 is placed on the glass plate 1 using a pressing jig 2 (hardened steel, diameter 10 mm, mirror finish) made of SUS304 with the glass plate 1 placed horizontally. Pressurize and measure the surface strength of the glass plate 1.
　図１において、ＳＵＳ３０４製の受け治具３（直径３０ｍｍ、接触部の曲率Ｒ２．５ｍｍ、接触部は焼入れ鋼、鏡面仕上げ）の上に、サンプルとなるガラス板１が水平に設置されている。ガラス板１の上方には、ガラス板１を加圧するための、加圧治具２が設置されている。 1, a glass plate 1 serving as a sample is horizontally installed on a receiving jig 3 made of SUS304 (diameter 30 mm, contact portion curvature R2.5 mm, contact portion is hardened steel, mirror finish). Above the glass plate 1, a pressurizing jig 2 for pressurizing the glass plate 1 is installed.
　本実施の形態においては、実施例及び比較例後に得られたガラス板１の上方から、ガラス板１の中央領域を加圧する。なお、試験条件は下記の通りである。
加圧治具２の下降速度：１．０（ｍｍ／ｍｉｎ）
　この時、ガラスが破壊された際の、破壊荷重（単位Ｎ）をＢＯＲ面強度とし、２０回の測定の平均値をＢＯＲ平均面強度とする。ただし、ガラス板の破壊起点がボール押しつけ位置より２ｍｍ以上離れている場合は、平均値算出のためのデータより除外する。 In this Embodiment, the center area | region of the glass plate 1 is pressurized from the upper direction of the glass plate 1 obtained after the Example and the comparative example. The test conditions are as follows.
Lowering speed of the pressure jig 2: 1.0 (mm / min)
At this time, the breaking load (unit N) when the glass is broken is defined as the BOR surface strength, and the average value of 20 measurements is defined as the BOR average surface strength. However, if the glass plate fracture starting point is 2 mm or more away from the ball pressing position, it is excluded from the data for calculating the average value.
　本発明の製造方法により得られるガラス基材は、所望の形状に切断する切断処理や面取り処理等の加工処理が行なわれた後、さらに化学強化処理が施され、所望の面強度を有する化学強化ガラスとすることができる。化学強化ガラスにおける圧縮応力層深さは、３０μｍ以上が好ましく、４０μｍ以上がより好ましい。また、表面圧縮応力は６００ＭＰａ以上が好ましく、７００ＭＰａ以上がより好ましい。具体的には、例えば、４２５～４６５℃の硝酸カリウム（ＫＮＯ３）溶融塩に２～２４時間浸漬させる。なお、ガラス基材は必ずしも化学強化処理が行われる必要はない。 The glass substrate obtained by the production method of the present invention is subjected to a processing treatment such as a cutting treatment or a chamfering treatment for cutting into a desired shape, and further subjected to a chemical strengthening treatment to provide a chemical strengthening having a desired surface strength. Can be glass. The depth of the compressive stress layer in the chemically strengthened glass is preferably 30 μm or more, and more preferably 40 μm or more. Further, the surface compressive stress is preferably 600 MPa or more, and more preferably 700 MPa or more. Specifically, for example, it is immersed in a molten potassium nitrate (KNO 3 ) salt at 425 to 465 ° C. for 2 to 24 hours. The glass substrate does not necessarily need to be chemically strengthened.
　以下に実施例を挙げ、本発明を具体的に説明するが、本発明はこれらに限定されない。 Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
＜評価方法＞
　本実施例における各種評価は以下に示す分析方法により行った。
（ガラスの評価：表面応力）
　本発明のガラス基材の圧縮応力層の圧縮応力値および圧縮応力層の深さは、表面応力計（例えば、折原製作所製ＦＳＭ－６０００）等を用いて測定することができる。また、圧縮応力層の深さは、ＥＰＭＡ（ｅｌｅｃｔｒｏｎ　ｐｒｏｂｅ　ｍｉｃｒｏ　ａｎａｌｙｚｅｒ）等を用いて測定したイオン交換深さによって代用することができる。実施例では、表面圧縮応力値（ＣＳ、単位はＭＰａ）および圧縮応力層の深さ（ＤＯＬ、単位はμｍ）は折原製作所社製表面応力計（ＦＳＭ－６０００）を用いて測定した。 <Evaluation method>
Various evaluations in this example were performed by the following analysis methods.
(Evaluation of glass: surface stress)
The compressive stress value of the compressive stress layer and the depth of the compressive stress layer of the glass substrate of the present invention can be measured using a surface stress meter (for example, FSM-6000 manufactured by Orihara Seisakusho). Further, the depth of the compressive stress layer can be substituted by an ion exchange depth measured using an EPMA (electron probe micro analyzer) or the like. In the examples, the surface compressive stress value (CS, unit is MPa) and the depth of the compressive stress layer (DOL, unit is μm) were measured using a surface stress meter (FSM-6000) manufactured by Orihara Seisakusho.
（ガラスの評価：除去量）
　ガラスの除去量厚みは、薬液処理前後の重量を分析用電子天秤（ＨＲ－２０２ｉ；ＡＮＤ製）により測定し、次の式を用いて厚み換算することにより求めた。
　（片面あたりの除去量厚み）＝（（処理前重量）－（処理後重量））／（ガラス比重）／処理面積／２ (Evaluation of glass: amount removed)
The glass removal amount thickness was determined by measuring the weight before and after the chemical treatment with an analytical electronic balance (HR-202i; manufactured by AND) and converting the thickness using the following formula.
(Removed thickness per side) = ((weight before treatment) − (weight after treatment)) / (glass specific gravity) / treated area / 2
（ガラスの評価：面強度）
　前述の〔ボールオンリング試験〕にて記載した方法に従い、ガラス面強度を測定した。 (Evaluation of glass: surface strength)
The glass surface strength was measured according to the method described in the above [Ball On Ring Test].
　下記各試験例のうち、例１－１、１－２、１－３、２－１、２－２、及び２－３は実施例であり、例１－４、及び２－４は比較例である。 Of the following test examples, Examples 1-1, 1-2, 1-3, 2-1, 2-2, and 2-3 are examples, and Examples 1-4 and 2-4 are comparative examples. It is.
＜例１－１＞
（生ガラス準備）
　サイズが５０ｍｍ×５０ｍｍ×０．７ｍｍであり、下記組成および比重のガラスＡを用いた。
ガラスＡ組成（モル％表示）：ＳｉＯ２　６４．４％、Ａｌ２Ｏ３　８．０％、Ｎａ２Ｏ　１２．５％、Ｋ２Ｏ　４．０％、ＭｇＯ　１０．５％、ＣａＯ　０．１％、ＳｒＯ　０．１％、ＢａＯ　０．１％、ＺｒＯ２　０．５％
ガラスＡ比重（ｇ／ｃｍ３）：２．４８、歪み点：５５６℃ <Example 1-1>
(Raw glass preparation)
A glass A having a size of 50 mm × 50 mm × 0.7 mm and having the following composition and specific gravity was used.
Glass A composition (expressed in mol%): SiO 2 64.4%, Al 2 O 3 8.0%, Na 2 O 12.5%, K 2 O 4.0%, MgO 10.5%, CaO 0. 1%, SrO 0.1%, BaO 0.1%, ZrO 2 0.5%
Glass A specific gravity (g / cm 3 ): 2.48, strain point: 556 ° C.
（イオン交換処理工程）
　ＳＵＳ製のカップに硝酸カリウム４７３１ｇ、炭酸カリウム１６０ｇ、硝酸ナトリウム８４９ｇを加え、マントルヒーターで４５０℃まで加熱して炭酸カリウム２ｍｏｌ％、Ｋ／Ｎａ質量比率が８．６の溶融塩を調製した。上記により得られたガラスＡを２００～４００℃に予熱した後、４５０℃の溶融塩に２時間浸漬し、イオン交換処理した後、室温付近まで冷却した。得られたガラスは水洗いし、次の工程に供した。 (Ion exchange process)
To a SUS cup, 4731 g of potassium nitrate, 160 g of potassium carbonate and 849 g of sodium nitrate were added and heated to 450 ° C. with a mantle heater to prepare a molten salt having a potassium carbonate concentration of 2 mol% and a K / Na mass ratio of 8.6. The glass A obtained above was preheated to 200 to 400 ° C., immersed in a molten salt at 450 ° C. for 2 hours, subjected to ion exchange treatment, and then cooled to near room temperature. The obtained glass was washed with water and subjected to the next step.
（酸処理工程）
　６．０重量％の硝酸（ＨＮＯ３；関東化学社製）をビーカーに用意し、ウォーターバスを用いて４０℃に温度調整を行った。前記イオン交換処理工程で得られたガラスを、調整した塩酸中に１２０秒間浸漬させ、酸処理を行い、その後純水で数回洗浄した後、エアブローにより乾燥した。こうして得られたガラスを次の工程に供した。 (Acid treatment process)
6.0% by weight of nitric acid (HNO 3 ; manufactured by Kanto Chemical Co., Inc.) was prepared in a beaker, and the temperature was adjusted to 40 ° C. using a water bath. The glass obtained in the ion exchange treatment step was immersed in adjusted hydrochloric acid for 120 seconds, acid-treated, then washed several times with pure water, and then dried by air blowing. The glass thus obtained was subjected to the next step.
（アルカリ処理工程）
　４．０重量％の水酸化ナトリウム水溶液をビーカーに用意し、ウォーターバスを用いて４０℃に温度調整を行った。酸処理工程で得られたガラスを、調整した水酸化ナトリウム水溶液中に１２０秒間浸漬させ、アルカリ処理を行い、その後純水で数回洗浄した後、エアブローにより乾燥した。
　以上より、例１－１のガラス基材を得た。 (Alkali treatment process)
A 4.0 wt% aqueous sodium hydroxide solution was prepared in a beaker, and the temperature was adjusted to 40 ° C. using a water bath. The glass obtained in the acid treatment step was immersed in the prepared sodium hydroxide aqueous solution for 120 seconds, subjected to alkali treatment, then washed several times with pure water, and then dried by air blowing.
From the above, the glass substrate of Example 1-1 was obtained.
＜例１－２＞
　硝酸カリウム４６８０ｇ、炭酸カリウム１７７ｇ、硝酸ナトリウム１３８４ｇを加え、を加え、マントルヒーターで４５０℃まで加熱して炭酸カリウム２ｍｏｌ％、Ｋ／Ｎａ質量比率が５．３の溶融塩を調製した以外は例１－１と同様にして例１－２のガラス基材を得た。
＜例１－３＞
　４５０℃の溶融塩に２４時間浸漬した以外は例１－２と同様にして例１－３のガラス基材を得た。 <Example 1-2>
Example 1 except that 4680 g of potassium nitrate, 177 g of potassium carbonate and 1384 g of sodium nitrate were added and heated to 450 ° C. with a mantle heater to prepare a molten salt having a potassium carbonate concentration of 2 mol% and a K / Na mass ratio of 5.3. In the same manner as in Example 1, a glass substrate of Example 1-2 was obtained.
<Example 1-3>
A glass substrate of Example 1-3 was obtained in the same manner as Example 1-2 except that it was immersed in a molten salt at 450 ° C. for 24 hours.
＜例２－１＞
　ガラスＡに代えて、５０ｍｍ×５０ｍｍ×０．７ｍｍであって下記組成および比重のガラスＢを用いた点以外は例１－１と同様に、例２－１のガラス基材を得た。
ガラスＢ組成（モル％表示）：ＳｉＯ２　６８％、Ａｌ２Ｏ３　１０％、Ｎａ２Ｏ　１４％、ＭｇＯ　８％
ガラスＢ比重（ｇ／ｃｍ３）：２．４１ <Example 2-1>
A glass substrate of Example 2-1 was obtained in the same manner as Example 1-1 except that glass B having a size of 50 mm × 50 mm × 0.7 mm and having the following composition and specific gravity was used instead of glass A.
Glass B composition (in mol%): SiO 2 68%, Al 2 O 3 10%, Na 2 O 14%, MgO 8%
Glass B specific gravity (g / cm 3 ): 2.41
＜例２－２＞
　硝酸カリウム４６８０ｇ、炭酸カリウム１７７ｇ、硝酸ナトリウム１３８４ｇを加え、を加え、マントルヒーターで４５０℃まで加熱して炭酸カリウム２ｍｏｌ％、Ｋ／Ｎａ質量比率が５．３の溶融塩を調製した以外は例２－１と同様にして例２－２のガラス基材を得た。
＜例２－３＞
　４５０℃の溶融塩に２４時間浸漬した以外は例２－２と同様にして例２－３のガラス基材を得た。 <Example 2-2>
Example 2 except that 4680 g of potassium nitrate, 177 g of potassium carbonate and 1384 g of sodium nitrate were added and heated to 450 ° C. with a mantle heater to prepare a molten salt of 2 mol% potassium carbonate and a K / Na mass ratio of 5.3. In the same manner as in Example 1, a glass substrate of Example 2-2 was obtained.
<Example 2-3>
A glass substrate of Example 2-3 was obtained in the same manner as in Example 2-2 except that it was immersed in a molten salt at 450 ° C. for 24 hours.
　上記により得られた各ガラス基材の評価結果を表１に示す。また、イオン交換処理工程、酸処理工程、および、アルカリ処理工程を実施していないガラスＡの評価結果を例１－４として、イオン交換処理工程、酸処理工程、および、アルカリ処理工程を実施していないガラスＢの評価結果を例２－４として表１に示す。 Table 1 shows the evaluation results of the glass substrates obtained as described above. In addition, the evaluation results of the glass A that has not been subjected to the ion exchange treatment step, the acid treatment step, and the alkali treatment step are taken as examples 1-4, and the ion exchange treatment step, the acid treatment step, and the alkali treatment step were performed Table 1 shows the evaluation results of the glass B that was not used as Example 2-4.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　上記より、本発明の製造方法により得られた実施例のガラス基材は、比較例のガラス（未処理の生ガラス）に比べ面強度が大幅に向上した。 From the above, the surface strength of the glass substrate of the example obtained by the production method of the present invention was greatly improved as compared with the glass of the comparative example (untreated raw glass).
　本発明を詳細に、また特定の実施態様を参照して説明したが、本発明の精神と範囲を逸脱することなく様々な変更や修正を加えることができることは当業者にとって明らかである。本出願は２０１５年１月２０日出願の日本特許出願（特願２０１５－００８８５１）に基づくものであり、その内容はここに参照として取り込まれる。 Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on January 20, 2015 (Japanese Patent Application No. 2015-008851), the contents of which are incorporated herein by reference.
　本発明によれば、面強度が大幅に向上したガラス基材を安全かつ低コストで得ることができる。本発明に係るガラス基材は、携帯電話、デジタルカメラまたはタッチパネルディスプレイ等のディスプレイ用カバーガラスや、車両のフロントガラス等の種々の用途に適用することができる。 According to the present invention, a glass base material having significantly improved surface strength can be obtained safely and at low cost. The glass substrate according to the present invention can be applied to various uses such as a cover glass for a display such as a mobile phone, a digital camera or a touch panel display, and a windshield of a vehicle.

Claims (15)

  1. 　生ガラスと、硝酸カリウムを含む無機塩とを接触させることによって、前記生ガラス中のＮａイオンと前記無機塩中のＫイオンとをイオン交換する工程を含むガラス基材の製造方法であって、
    　前記無機塩はＫ２ＣＯ３、Ｎａ２ＣＯ３、ＫＨＣＯ３、ＮａＨＣＯ３、Ｋ３ＰＯ４、Ｎａ３ＰＯ４、Ｋ２ＳＯ４、Ｎａ２ＳＯ４、ＫＯＨ及びＮａＯＨからなる群より選ばれる少なくとも一種の塩を含み、Ｋ／Ｎａ比率が質量比で１以上１５以下であり、かつ
    　前記イオン交換する工程の後にガラスを洗浄する工程、
    　前記洗浄する工程の後にガラスを酸処理する工程、及び
    　前記酸処理する工程の後にガラスをアルカリ処理する工程を含む、ガラス基材の製造方法。     A method for producing a glass substrate, comprising a step of ion-exchanging Na ions in the raw glass and K ions in the inorganic salt by contacting the raw glass with an inorganic salt containing potassium nitrate,
    The inorganic salt is at least selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 , NaHCO 3 , K 3 PO 4 , Na 3 PO 4 , K 2 SO 4 , Na 2 SO 4 , KOH and NaOH. A step of containing a kind of salt, wherein the K / Na ratio is 1 to 15 in terms of mass ratio, and the glass is washed after the ion exchange step;
    A method for producing a glass substrate, comprising: a step of acid-treating glass after the washing step; and a step of alkali-treating glass after the step of acid treatment.
  2. 　前記酸処理する工程の後に、ガラスを洗浄する工程を有することを特徴とする請求項１記載のガラス基材の製造方法。 2. The method for producing a glass substrate according to claim 1, further comprising a step of washing the glass after the acid treatment step.
  3. 　前記アルカリ処理する工程の後に、ガラスを洗浄する工程を有することを特徴とする請求項１記載のガラス基材の製造方法。 2. The method for producing a glass substrate according to claim 1, further comprising a step of washing the glass after the step of alkali treatment.
  4. 　生ガラスと、無機塩とを接触させることによって、前記生ガラス中のＮａイオンと前記無機塩中のＫイオンとをイオン交換する工程を含むガラス基材の製造方法であって、
    　前記無機塩は、Ｋ／Ｎａ比率が質量比で１以上１５以下であり、かつ
    　前記イオン交換する工程の後にガラスを洗浄する工程、
    　前記洗浄する工程の後にガラスを酸処理する工程、及び
    　前記酸処理する工程の後にガラスをアルカリ処理する工程を含む、ガラス基材の製造方法。     A method for producing a glass substrate, comprising a step of ion-exchanging Na ions in the raw glass and K ions in the inorganic salt by bringing the raw glass into contact with an inorganic salt,
    The inorganic salt has a K / Na ratio of 1 to 15 in terms of mass ratio, and the step of washing the glass after the ion exchange step;
    A method for producing a glass substrate, comprising: a step of acid-treating glass after the washing step; and a step of alkali-treating glass after the step of acid treatment.
  5. 前記無機塩は、硝酸カリウムを含む請求項４に記載のガラス基材の製造方法。 The said inorganic salt is a manufacturing method of the glass base material of Claim 4 containing potassium nitrate.
  6. 　前記酸処理する工程は、ｐＨ７未満である溶液を用いることを特徴とする請求項１または４記載のガラス基材の製造方法。 The method for producing a glass substrate according to claim 1 or 4, wherein the acid treatment step uses a solution having a pH of less than 7.
  7. 　前記ｐＨ７未満である溶液は弱酸であることを特徴とする請求項６記載のガラス基材の製造方法。 The method for producing a glass substrate according to claim 6, wherein the solution having a pH of less than 7 is a weak acid.
  8. 　前記ｐＨ７未満である溶液は強酸であることを特徴とする請求項６記載のガラス基材の製造方法。 The method for producing a glass substrate according to claim 6, wherein the solution having a pH of less than 7 is a strong acid.
  9. 　前記酸処理する工程は、１００℃以下の温度でおこなうことを特徴とする請求項１または４記載のガラス基材の製造方法。 The method for producing a glass substrate according to claim 1 or 4, wherein the acid treatment step is performed at a temperature of 100 ° C or lower.
  10. 　前記酸処理する工程をおこなう時間は、１０秒～５時間であることを特徴とする請求項１または４記載のガラス基材の製造方法。 The method for producing a glass substrate according to claim 1 or 4, wherein the time for performing the acid treatment is 10 seconds to 5 hours.
  11. 　前記アルカリ処理する工程は、ｐＨ７超過の溶液を用いることを特徴とする請求項１または４記載のガラス基材の製造方法。 The method for producing a glass substrate according to claim 1 or 4, wherein a solution having a pH of more than 7 is used in the alkali treatment step.
  12. 　前記ｐＨ７超過の溶液は弱塩基であることを特徴とする請求項１１記載のガラス基材の製造方法。 12. The method for producing a glass substrate according to claim 11, wherein the solution having a pH exceeding 7 is a weak base.
  13. 　前記ｐＨ７超過の溶液は強塩基であることを特徴とする請求項１１記載のガラス基材の製造方法。 12. The method for producing a glass substrate according to claim 11, wherein the solution having a pH exceeding 7 is a strong base.
  14. 　前記アルカリ処理する工程は、０℃以上１００℃以下の温度でおこなうことを特徴とする請求項１または４記載のガラス基材の製造方法。 The method for producing a glass substrate according to claim 1 or 4, wherein the alkali treatment step is performed at a temperature of 0 ° C or higher and 100 ° C or lower.
  15. 　前記アルカリ処理する工程をおこなう時間は、１０秒～５時間であることを特徴とする請求項１または４記載のガラス基材の製造方法。 The method for producing a glass substrate according to claim 1 or 4, wherein the time for performing the alkali treatment step is 10 seconds to 5 hours.
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