JP2015151329A - Method for manufacturing strengthened glass, and strengthened glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method enabling appropriate management of a stress state of a bent part of a strengthened glass.SOLUTION: A method for manufacturing a strengthened glass includes a step of simultaneously obtaining a strengthening glass 32 having a bent part and a flat plate-shaped strengthening glass 31 by immersing the strengthening glass 32 having a bent part and the flat plate-shaped strengthening glass 31 in the same ion exchange solution 28. The strengthening glass 32 having a bent part is obtained by heat treating a base material glass to (slow cooling point -50°C) or more, and bending processing the product followed by cooling a temperature range from a slow cooling point to a strain point. The flat plate-shaped strengthening glass 31 is obtained by heat treating a base material glass to (slow cooling point -50°C) or more followed by cooling a temperature range from a slow cooling point to a strain point. The flat plate-shaped strengthening glass has a thermal history nearly the same as that of the strengthening glass having a bent part.

Description

  The present invention relates to a method for producing tempered glass and tempered glass, and more particularly to a method for producing tempered glass having a bent portion.

  Mobile phones equipped with touch panels have become widespread. As a cover glass of such a mobile phone, ion-exchanged glass (so-called tempered glass) is used. Since tempered glass has higher mechanical strength than unstrengthened glass, it is suitable for this application (see Patent Document 1 and Non-Patent Document 1).

  In recent years, this application requires tempered glass having a bend, such as a bend and / or a bend. The tempered glass having a bent portion is obtained by, for example, molding and cutting molten glass to obtain a flat base glass, and then bending the base glass by heat treatment to obtain a tempered glass having a bent portion. After it is obtained, it can be produced by performing an ion exchange treatment (see Patent Documents 2 and 3).

JP 2006-83045 A US Pat. No. 7,168,047 JP 2001-247342 A

Tetsuro Izumiya et al., “New Glass and its Properties”, first edition, Management System Research Institute, Inc., August 20, 1984, p. 451-498

  In cover glass applications for mobile phones, there is an increasing demand for weight reduction, that is, thickness reduction. On the other hand, when the conventional tempered glass is made thinner, the internal tensile stress becomes excessive, and there is a possibility that fragments are scattered when the tempered glass is broken or the tempered glass is self-destructed. Therefore, when thinning the tempered glass, it is necessary to strictly manage the compressive stress value and thickness of the compressive stress layer of the tempered glass.

  In the case of flat tempered glass, the compressive stress value and thickness of the compressive stress layer on the surface can be calculated from the number of interference fringes observed with a surface stress meter and their spacing.

  However, in the case of tempered glass having a bent portion, it is extremely difficult to appropriately measure the compressive stress value and thickness of the compressive stress layer existing on the surface of the bent portion due to the nature of the surface stress meter. As a result, about the tempered glass which has a bending part, the stress state of the bending part was not able to be managed appropriately.

  Then, this invention is made | formed in view of the said situation, The technical subject is to devise the method which can manage appropriately the stress state of the bending part of tempered glass.

  As a result of various studies, the present inventors have found that the above technical problem can be solved by performing ion exchange treatment simultaneously on the reinforcing glass having a bent portion and the flat reinforcing glass. It is proposed as an invention. That is, in the method for producing tempered glass of the present invention, the tempered glass having a bent part and the tempered glass having a bent part are immersed in the same ion exchange solution by immersing the tempered glass having the bent part and the flat glass-like tempered glass. It has the process of obtaining simultaneously. If it does in this way, the stress state of a bending part can be estimated about the tempered glass which has a bending part by measuring the stress state of flat plate-shaped tempered glass. As a result, it becomes possible to properly manage the stress state of the bent portion. The flat tempered glass may be used only for estimating the stress state of the bent portion of the tempered glass, but may be used as a product.

  2ndly, it is preferable that the manufacturing method of the tempered glass of this invention has the heat | fever history substantially the same as the bending part of the tempered glass in which flat plate-shaped tempering glass has a bending part. If it does in this way, the stress state of a bending part can be correctly estimated about the tempered glass which has a bending part by measuring the stress state of flat plate-shaped tempered glass. As a result, it becomes possible to strictly manage the stress state of the bent portion. Here, “substantially the same thermal history as the bending portion of the strengthening glass” means that the heat treatment is performed under substantially the same conditions as the bending portion of the strengthening glass (however, heat treatment during forming, that is, forming) The time-slow cooling treatment is excluded).

  Even if the tempering glasses having different thermal histories are subjected to the ion exchange treatment under the same conditions, the obtained tempered glass is in a different stress state depending on the thermal history. Specifically, the tempered glass that has undergone rapid and rapid heat treatment has a greater compressive stress value in the compressive stress layer and a smaller depth of the compressive stress layer than tempered glass that has been sufficiently slowly cooled. Therefore, in order to accurately estimate the stress state of the bent part, the reinforcing glass having the bent part is given to the flat reinforcing glass with the heat history substantially the same as the bent part of the reinforcing glass. It is preferable to ion-exchange the flat reinforcing glass under the same conditions.

  Third, the method for producing tempered glass according to the present invention includes heat-treating the base glass to a temperature equal to or higher than the base glass (annealing point-50 ° C.), bending the base glass, It is preferable to obtain a tempered glass having a bent portion by cooling the temperature range from the annealing point to the strain point. If it does in this way, the tempered glass which has a bending part can be produced efficiently. Here, “annealing point” and “strain point” refer to values measured based on the method of ASTM C336.

  Fourth, the method for producing tempered glass according to the present invention includes the step of annealing the base glass from the annealing point to the strain point of the base glass after heat-treating the base glass to a temperature equal to or higher than the base glass (annealing point−50 ° C.). It is preferable to obtain a flat glass for strengthening by cooling the temperature range.

  Fifth, in the method for producing tempered glass of the present invention, the base glass is preferably flat. If it does in this way, the precision of a bending process can be raised.

  Sixth, in the method for producing tempered glass of the present invention, after the base glass is heat-treated, the temperature range from the annealing point to the strain point is cooled at a cooling rate of 0.2 ° C./min to 200 ° C./min. It is preferable to do. If it does in this way, after preventing the break at the time of a bending process, the tempered glass which has a bending part can be produced efficiently.

  Seventhly, in the method for producing tempered glass of the present invention, it is preferable that the amount of warpage of the flat tempered glass is 1 mm or less. If it does in this way, it will become easy to measure the stress state of tabular tempered glass, and it will become easy to manage the stress state of a bent part as a result. Here, the “warp amount” refers to the maximum thickness of the thickness gauge that can be inserted into the gap between the tempered glass and the surface plate when the tempered glass is placed on the surface plate.

  Eighth, in the method for producing tempered glass of the present invention, the flat tempered glass has a compressive stress layer, the compressive stress value of the compressive stress layer is 50 MPa or more, and the thickness of the compressive stress layer is 10 μm or more. preferable. Here, “the compressive stress value of the compressive stress layer” and “the thickness of the compressive stress layer” are measured by using a surface stress meter (for example, FSM-6000 manufactured by Toshiba Corporation) and observing the number of interference fringes and their intervals. It is calculated by this.

Ninth, the method of producing glass of the present invention, the reinforcing glass, as a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 0~30%, Na 2 O 5~25% preferably contains _K 2 O _0~10%.

Tenth production method of the tempered glass of the present invention, the reinforcing glass, as a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 10~28%, B 2 O 3 0~10 _{%, Li 2 O 0~10%,} Na 2 O 8~20%, preferably contains K 2 O 0~10%.

  Eleventhly, in the method for producing tempered glass of the present invention, the tempered glass preferably has a softening point of 1050 ° C. or lower. If it does in this way, it will become easy to improve thermal workability. Here, the “softening point” refers to a value measured based on the method of ASTM C338.

12thly, it is preferable that the manufacturing method of the tempered glass of this invention is 60-110 * 10 < ^-7 > / degreeC of thermal expansion coefficients of the glass for reinforcement | strengthening. Here, the “thermal expansion coefficient” is a value measured with a dilatometer, and indicates an average value in a temperature range of 25 to 380 ° C.

Thirteenthly, in the method for producing tempered glass of the present invention, the liquid phase viscosity of the tempered glass is preferably 10 ^4.0 dPa · s or more. Here, “liquid phase viscosity” refers to a value obtained by measuring the viscosity of glass at the liquid phase temperature by a platinum ball pulling method. “Liquid phase temperature” is obtained when glass powder passing through a standard sieve 30 mesh (500 μm sieve opening) and remaining on 50 mesh (300 μm sieve opening) is placed in a platinum boat and kept in a temperature gradient furnace for 24 hours. , Refers to the temperature at which crystals (initial phase) precipitate.

  Fourteenth, after the base glass is heat-treated at a temperature equal to or higher than that of the base glass (annealing point −50 ° C.) and the base glass is bent, the temperature from the annealing point to the strain point of the base glass. A step of obtaining glass for strengthening having a bent part by cooling the zone, and after heat-treating the base glass to a temperature not lower than (annealing point−50 ° C.) of the base glass, the annealing point of the base glass Cooling the temperature range from the strain point to the strain point to obtain a flat plate-shaped reinforcing glass, and the thermal history of the flat glass-shaped reinforcing glass is substantially the same as the thermal history of the bent portion of the reinforcing glass. Then, it is characterized in that a tempered glass having a bent portion and a flat tempered glass are respectively produced. If it does in this way, the stress state of the bending part of tempered glass can be correctly estimated by measuring the stress state of flat tempered glass. As a result, it becomes possible to strictly manage the stress state of the bent portion of the tempered glass. Here, after bending the base glass, a step of obtaining a strengthening glass having a bent portion by cooling the temperature range from the annealing point to the strain point of the base glass, and the base glass as the base glass After heat-treating the glass at a temperature of (annealing point-50 ° C.) or higher, by cooling the temperature range from the annealing point of the base glass to the strain point, a step of obtaining a flat plate-shaped reinforcing glass is, Although it may be performed simultaneously, it does not need to be performed simultaneously.

  15thly, the manufacturing method of the tempered glass of this invention is a manufacturing method of the tempered glass which obtains the tempered glass which has a bending part by immersing the glass for strengthening which has a bending part in an ion exchange solution, It has the process of managing the stress state of the bending part of tempered glass which has the above on the basis of the stress state of flat plate-like tempered glass. If it does in this way, the stress state of the bent part of tempered glass can be presumed based on the stress state of tabular tempered glass. As a result, the stress state of the bent portion of the tempered glass can be properly managed.

  16thly, it is preferable that the tempered glass of this invention is produced by said manufacturing method of tempered glass.

  Seventeenth, the tempered glass of the present invention has a bent portion, a compressive stress layer on the surface of the bent portion, and a compressive stress value of the compressive stress layer in the bent portion is 50 MPa or more. The thickness is 10 μm or more.

  Eighteenth, the tempered glass of the present invention is preferably used for a cover glass of a touch panel display.

  Nineteenth, the tempered glass of the present invention is preferably used for a cover glass of a mobile phone.

It is the perspective view which illustrated the embodiment of the tempered glass which has a bending part which concerns on this invention. It is the perspective view which illustrated the embodiment of the tempered glass which has a bending part which concerns on this invention. It is a three-way conceptual diagram which illustrated the embodiment of the tempered glass which has a bending part which concerns on this invention. It is the perspective view which illustrated the embodiment of the tempered glass which has a bending part which concerns on this invention. It is a cross-sectional conceptual diagram which shows an example of the manufacturing method of the tempered glass of this invention.

  In the method for producing tempered glass of the present invention, a base glass is first prepared. For the base glass, for example, glass raw materials (including cullet) prepared to have a predetermined glass composition are put into a continuous melting furnace, heated and melted at 1500 to 1700 ° C., clarified, and then supplied to a molding apparatus. Then, it can be produced by forming into a flat plate shape and slowly cooling. The base glass is subjected to heat treatment after being cut into a predetermined shape.

  As a forming method of the base glass, an overflow down draw method is preferable. The overflow downdraw method can produce a large amount of high-quality flat glass and can easily make the glass thinner and larger.

  In addition to the overflow downdraw method, various molding methods can be employed. For example, a float method, a downdraw method (slot down method, redraw method, etc.), a rollout method, a press method, etc. can be employed.

  In the method for producing tempered glass of the present invention, the base glass is preferably in the form of a flat plate, and the surface is preferably unpolished. The average surface roughness Ra of the surface of the base glass is preferably 10 mm or less, 5 mm or less, 4 mm or less, 3 mm or less, particularly 2 mm or less. If it does in this way, the precision of a bending process can be raised. Here, the average surface roughness (Ra) of the surface can be measured by a method based on SEMI D7-97 “Measurement method of surface roughness of FPD glass substrate”.

  In the method for producing tempered glass of the present invention, the base glass is preferably subjected to a bending process by heat-treating the base glass to a temperature equal to or higher than (annealing point−50 ° C.) of the base glass. If the heat treatment temperature is too low, it becomes difficult to perform bending in a short time. Therefore, the bending temperature is preferably (annealing point−10 ° C.) or more, (annealing point−5 ° C.) or more, annealing point or more, (annealing point + 5 ° C.) or more, particularly (annealing point + 20). Or higher). If the heat treatment temperature is too high, the surface smoothness of the bent portion is likely to be impaired, and the dimensional accuracy of the bent portion is likely to be lowered. Therefore, the heat treatment temperature is preferably (softening point −5 ° C.) or lower, (softening point −15 ° C.) or lower, (softening point −20 ° C.) or lower, particularly preferably (softening point −30 ° C.) or lower.

  In the method for producing tempered glass of the present invention, it is preferable to cool the temperature range from the annealing point to the strain point at a cooling rate of 0.2 ° C./min to 200 ° C./min after heat-treating the base glass. . If the cooling rate is too high, tensile stress due to heat distribution is generated in the glass, and the glass may be damaged. Therefore, the cooling rate is preferably 100 ° C./min or less, 50 ° C./min or less, particularly 10 ° C./min or less. On the other hand, if the cooling rate is too slow, the production efficiency of the tempered glass tends to decrease. Therefore, the cooling rate is preferably 0.2 ° C / min or more, 0.3 ° C / min or more, 0.5 ° C / min or more, 1 ° C / min or more, 2 ° C / min or more, particularly 3 ° C / min or more. It is.

  In the method for producing tempered glass of the present invention, it is preferable that the flat glass-shaped tempering glass has substantially the same thermal history as that of the tempered glass having a bent part. In addition, it is preferable that the flat reinforcing glass has substantially the same thermal history as that of the bent portion from the viewpoint of management of the stress state, but partially has substantially the same thermal history as that of the bent portion. You may have.

  Various methods can be adopted as a bending method. In particular, a method of press-molding a flat plate-shaped reinforcing glass with a mold is preferable, and it is more preferable to pass through a heat treatment furnace in a state where the flat plate-shaped reinforcing glass is sandwiched between molds having a predetermined shape. If it does in this way, the dimensional accuracy of a bent part can be raised. In addition, after placing a flat plate-shaped reinforcing glass on a mold having a predetermined shape, the reinforcing glass is softened and deformed by its own weight along the shape of the mold by heat-treating a part or the whole of the reinforcing glass. The method of making it also preferable. If it does in this way, the manufacture efficiency of tempered glass which has a bent part can be raised.

  In the method for producing tempered glass of the present invention, it is preferable that the bent portion of the tempered glass is a bent portion and / or a bent portion. If it does in this way, the designability of tempered glass can be raised. Hereinafter, the shape of the tempered glass having a bent portion will be described in detail.

  The bent portion is preferably formed in the edge region of at least one side of the rectangular tempered glass, more preferably formed in the opposite edge region, and formed in the entire edge region. Further preferred. If it does in this way, when it is set as exterior parts etc., it will become difficult to expose an end surface outside, and tempered glass will become difficult to be damaged from an end surface by physical impact.

  The tempered glass having a bent portion preferably has a flat plate portion in addition to the bent portion. If it does in this way, when it is set as exterior parts etc., it will become possible to make a flat plate part respond | correspond to the operation area | region of a touchscreen, and the surface (except an end surface) of a bending part will be made to respond | correspond to an outer surface. When the surface of the bent portion (excluding the end surface) is made to correspond to the outer surface, the end surface is hardly exposed to the outside, and the tempered glass is not easily damaged from the end surface by physical impact.

  The curved portion is preferably formed in the entire width direction or length direction of the tempered glass, and more preferably formed in the entire width direction and length direction. If it does in this way, it will become difficult to concentrate stress on a specific part, and when it is set as an exterior part etc., it will become difficult to damage a tempered glass by a physical impact. In addition, when forming a curved part in the whole width direction and a length direction, it is preferable to provide a difference in the curve degree of the width direction, and the curve degree of a length direction. If it does in this way, the designability of tempered glass can be raised.

  In the case of tempered glass having a bent portion, it is preferable to grind and / or polish the end face. If it does in this way, when it is set as an exterior component etc., it can be set as the shape which cannot expose an end surface outside.

  In the case of tempered glass having a bent portion, it is preferable to grind and / or polish the end face before bending, and in this case, the end face is preferably chamfered. Further, the chamfered shape is preferably an R surface shape (curved surface shape) or a thread chamfered shape. If it does in this way, the end surface strength of glass for strengthening and tempered glass can be raised.

  It is also preferable to grind and / or polish the end face after bending and before the ion exchange treatment. If it does in this way, when it is set as exterior parts etc., after making an end surface into the shape which is hard to expose outside, the situation where a compressive-stress layer falls by heat processing can be prevented.

  The thickness of the bent portion is preferably 0.3 mm or more, 0.5 mm or more, 0.7 mm or more, 1.0 mm or more, 1.3 mm or more, particularly 1.5 mm or more from the viewpoint of mechanical strength. On the other hand, the thickness of the bent portion is preferably 3.0 mm or less, 1.5 mm or less, 0.7 mm or less, 0.5 mm or less, particularly 0.3 mm or less from the viewpoint of weight reduction.

  FIG. 1 is a perspective view illustrating an embodiment of a tempered glass having a bent portion according to the present invention. FIG. 1A shows a bent portion 1 (bent angle is about 90 °) in both end edge regions of the tempered glass in the plate width direction, and a flat plate portion 2 in the central region. Here, the end surface 3 of the bent portion 1 is inclined by 90 ° from the thickness direction of the flat plate portion 2. FIG. 1B has a bent portion 4 (bending angle is about 45 °) in both end edge regions of the tempered glass in the plate width direction, and a flat plate portion 5 in the central region. Here, the end surface 6 of the bent portion 4 is inclined by 45 ° from the plate thickness direction of the flat plate portion 5. FIG. 1C has a bent portion 7 (bending angle is about 45 °) in both end edge regions of the tempered glass in the plate width direction, and a flat plate portion 8 in the central region. Here, the end surface 9 of the bent portion 7 is in the thickness direction of the flat plate portion 8. And it is preferable that the end surface 9 of the bending part 7 is formed by grinding and / or grinding | polishing after a bending process and before a reinforcement process. In FIG. 1D, the whole of the tempered glass in the plate width direction is curved in an arc shape to form a curved portion 10, and the opposite end surfaces 11 in the plate width direction are inclined from the vertical direction according to the degree of the curve. . In FIG. 1E, the whole of the tempered glass in the plate width direction is curved in an arc shape to form a curved portion 12, and the opposite end faces 13 in the plate width direction are hypothetical in contact with the vertical direction, that is, the central portion of the curved portion 12. The direction is perpendicular to the plane. Here, the opposing end faces 13 in the plate width direction are preferably formed by grinding and / or polishing after bending and before the strengthening treatment.

  FIG. 2 is a perspective view illustrating an embodiment of tempered glass having a bent portion according to the present invention. FIG. 2A shows a bent portion 14 (bending angle is about 90 °) in the left edge region in the plate width direction of the tempered glass, and the other region is a flat plate portion 15. Here, the end surface 16 of the bent portion 14 is inclined by 90 ° from the thickness direction of the flat plate portion 15. FIG. 2B has a bent portion 17 (bending angle is about 45 °) in the left edge region in the plate width direction of the tempered glass, and the other region is a flat plate portion 18. Here, the end surface 19 of the bent portion 17 is inclined by 45 ° from the plate thickness direction of the flat plate portion 18. FIG. 2C shows a bent portion 20 (bending angle is about 45 °) in the left edge region in the plate width direction of the tempered glass, and the other region is a flat plate portion 21. Here, the end surface 22 of the bent portion 20 is in the thickness direction of the flat plate portion 21.

FIG. 3 is a three-way conceptual diagram illustrating an embodiment of a tempered glass having a bent portion according to the present invention, wherein (a) shows a front view, (b) shows a side view, and (c) shows a plan view. Is shown. As can be seen from FIG. 3, the bent portion 23 (bending angle is about 75 °) is formed in the entire edge region of the tempered glass, and the flat plate portion 24 is formed in the central region. Here, the end face 25 of the bent portion 23 is inclined by about 90 ° from the plate thickness direction of the flat plate portion 24.

  FIG. 4 is a perspective view illustrating an embodiment of tempered glass having a bent portion according to the present invention. As can be seen from FIG. 5, the entire tempered glass in the plate width direction is curved in an arc shape, and the entire length direction is curved in an arc shape to form a curved portion 26. Here, the degree of curvature in the plate width direction is smaller than the degree of curvature in the length direction.

In the method for producing tempered glass of the present invention, the tempered glass is immersed in an ion exchange solution to perform an ion exchange treatment. In particular, it is preferable to immerse the reinforcing glass having a bent portion and the flat reinforcing glass in the same ion exchange solution. FIG. 5 is a conceptual cross-sectional view showing an example of a method for producing tempered glass of the present invention. As can be seen from FIG. 5, an ion exchange solution (KNO ₃ solution) 28 is placed in the ion exchange tank 27. Baskets 29 and 30 are immersed in the KNO ₃ solution 28. A flat plate-shaped reinforcing glass 31 is accommodated in the basket 29, and a reinforcing glass 32 having a bent portion is accommodated in the basket 30. The tempered glass 31 having a flat plate shape and the tempering glass 32 having a bent portion are immersed in the same KNO ₃ solution 28 and subjected to ion exchange treatment under the same conditions. A tempered glass having

The ion exchange treatment can be performed, for example, by immersing the strengthening glass in a KNO ₃ solution at 390 to 550 ° C. for 0.5 to 8 hours. What is necessary is just to select optimal conditions for the ion exchange conditions in consideration of the viscosity characteristics of the glass for strengthening, application, plate thickness, internal tensile stress, and the like.

Various ion exchange solutions can be adopted as the ion exchange solution. From the viewpoint of ion exchange efficiency, a KNO ₃ solution or a mixed solution of KNO ₃ and NaNO ₃ is preferable.

In the method for producing tempered glass of the present invention, the compressive stress value of the compressive stress layer (particularly the compressive stress layer corresponding to the bending portion) is 50 MPa or more, 100 MPa or more, 300 MPa or more, 500 MPa or more, 600 MPa or more, particularly 700 MPa or more. It is preferable to perform ion exchange treatment. As the compressive stress value increases, the mechanical strength of the tempered glass increases. On the other hand, when an extremely large compressive stress is formed on the surface, microcracks are easily generated on the surface, and conversely, the mechanical strength of the tempered glass may be lowered. In addition, if an extremely large compressive stress is formed on the surface, the internal tensile stress may become extremely high. Therefore, the ion exchange treatment may be performed so that the compressive stress value of the compressive stress layer is 1300 MPa or less. preferable. In addition, if the content of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , MgO, ZnO in the glass composition is increased and the content of SrO, BaO is decreased, the compressive stress value of the compressive stress layer can be increased. Moreover, when the ion exchange time is shortened or the ion exchange temperature is lowered, the compressive stress value of the compressive stress layer can be increased.

In the method for producing tempered glass according to the present invention, ions are formed so that the thickness of the compressive stress layer (particularly the compressive stress layer corresponding to the bent portion) is 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, particularly 60 μm or more. It is preferable to perform an exchange process. In particular, in the case of tempered glass having a bent portion, the surface of the bent portion is more likely to come into direct contact with a finger or the like, and the mechanical strength of the tempered glass may be significantly reduced due to handling flaws. Therefore, if the thickness of the compressive stress layer is increased, the tempered glass becomes difficult to break from the bent portion even if the bent portion is deeply damaged. On the other hand, in order to prevent the self-destruction of the tempered glass, the thickness of the compressive stress layer is preferably 200 μm or less. In addition, if the content of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , MgO, ZnO in the glass composition is increased and the content of SrO, BaO is decreased, the thickness of the compressive stress layer can be increased. Furthermore, when the ion exchange time is lengthened or the ion exchange temperature is raised, the thickness of the compressive stress layer can be increased.

  In the method for producing tempered glass of the present invention, the internal tensile stress (particularly the internal tensile stress corresponding to the bending portion) is 150 MPa or less, 140 MPa or less, 130 MPa or less, 120 MPa or less, 110 MPa or less, 100 MPa or less, 90 MPa or less, 80 MPa or less. In particular, the ion exchange treatment is preferably performed so that the pressure is 70 MPa or less. If it does in this way, it will become easy to prevent self-destruction of tempered glass. The internal tensile stress can be calculated by the following formula 1.

  In the method for producing tempered glass of the present invention, the warpage amount of the tempered glass having a flat plate shape is preferably 1 mm or less, 0.8 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, 0.2 mm or less, It is 0.1 mm or less, especially 0.05 mm or less. If the amount of warpage is greater than 1 mm, it becomes difficult to measure the compressive stress value and thickness of the compressive stress layer with a surface stress meter.

  In the method for producing tempered glass of the present invention, the reason why the glass composition of the tempering glass (base glass and tempered glass is the same) is limited as described above will be described below. In addition, in description of the containing range of each component,% display points out the mass% unless there is particular notice.

SiO ₂ is a component that forms a network of glass. The content of SiO ₂ is preferably 45 to 75%, 50 to 75%, 55 to 72%, 56 to 71%, 57 to 70%, 58 to 70%, 59 to 70%, especially 60 to 70%. is there. If the content of SiO ₂ is too small, vitrification becomes difficult, and the thermal expansion coefficient becomes too high, so that the thermal shock resistance tends to decrease. On the other hand, if the content of SiO ₂ is too large, the meltability, formability, and bending workability tend to be lowered, and the thermal expansion coefficient becomes too low, making it difficult to match the thermal expansion coefficient of the surrounding materials.

Al ₂ O ₃ is a component that improves ion exchange performance, and is a component that increases the strain point and Young's modulus. The content of Al ₂ O ₃ is preferably 0 to 30%. When the content of Al ₂ O ₃ is too small, there is a possibility which can not be sufficiently exhibited ion exchange performance. Moreover, there is a possibility that the crack generation rate becomes high. Therefore, the preferred lower limit range of Al ₂ O ₃ is 1% or more, 3% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, 12% These are 13% or more, 14% or more, 15% or more, particularly 16% or more. On the other hand, when the content of Al ₂ O ₃ is too large, devitrification crystal glass becomes easy to precipitate, hardly molded into a flat plate shape by an overflow down draw method or the like. In particular, when an alumina molded refractory is used to form a flat plate by the overflow downdraw method, spinel devitrified crystals are likely to precipitate at the interface with the alumina molded refractory. In addition, the thermal expansion coefficient becomes too low, making it difficult to match the thermal expansion coefficient of the surrounding material. Moreover, acid resistance also falls and it becomes difficult to apply to an acid treatment process. Furthermore, the high-temperature viscosity becomes high, and the meltability and bending workability tend to be lowered. Therefore, the preferable upper limit range of Al ₂ O ₃ is 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, particularly 24% or less.

B ₂ O ₃ is a component that lowers the high temperature viscosity, density, annealing point, and softening point, stabilizes the glass, makes it difficult to precipitate crystals, and lowers the liquidus temperature. Moreover, it is a component which lowers the crack occurrence rate and increases scratch resistance. However, if the content of B ₂ O ₃ is too large, coloring of the glass surface called burnt occurs due to ion exchange, water resistance is lowered, and the thickness of the compressive stress layer tends to be reduced. Therefore, the preferable range of B ₂ O ₃ is 0 to 10%, 0 to 9%, 0 to 8%, 0 to 7%, 0 to 6%, 0 to 5%, 0 to 4%, and 0 to 3%. 0-2%, especially 0-1%.

Na ₂ O is an ion exchange component, and is a component that lowers the high temperature viscosity and improves the meltability and moldability. Na ₂ O is also a component that improves devitrification resistance and reactivity with the molded product refractory. When Na 2 _O content is too small, or reduced meltability, lowered coefficient of thermal expansion tends to decrease the ion exchange performance. Therefore, the content of Na ₂ O is preferably 5% or more, 7% or more, more than 7%, 8% or more, 9% or more, 10% or more, 11% or more, particularly 12% or more. On the other hand, when the content of Na ₂ O is too large, the thermal expansion coefficient becomes too high, the thermal shock resistance is lowered, and it becomes difficult to match the thermal expansion coefficient of the surrounding materials. In addition, the strain point may be excessively lowered or the component balance of the glass composition may be lost, and the devitrification resistance may be deteriorated. Therefore, the content of Na ₂ O is preferably 25% or less, 23% or less, 21% or less, 20% or less, 19.5% or less, 19% or less, 18.5% or less, 18% or less, 17. 5% or less, particularly 17% or less.

K ₂ O is a component that promotes ion exchange, and is a component that easily increases the thickness of the compressive stress layer among alkali metal oxides. Moreover, it is a component which reduces high temperature viscosity and improves a meltability and a moldability. Furthermore, it is also a component that improves devitrification resistance. However, if the content of K ₂ O is too large, the thermal expansion coefficient becomes too high, and the thermal shock resistance is lowered or it is difficult to match the thermal expansion coefficient of the surrounding materials. Moreover, there is a tendency that the strain point is excessively lowered, the component balance of the glass composition is lacking, and the devitrification resistance is lowered. Therefore, the preferable upper limit range of K ₂ O is 10% or less, 9% or less, 8% or less, 7% or less, particularly 6% or less. Incidentally, when adding _{K 2} O, the preferred amount is 0.1% or more, 0.5% or more, more than 1%, 1.5% or more, particularly 2% or more. Also, if to avoid as much as possible the addition of _{K 2} O, the preferred content of 0 to 1%, less than 0 to 1.0%, in particular from 0 to 0.05%.

  In addition to the above components, for example, the following components may be added.

Li ₂ O is an ion exchange component, and is a component that lowers the high-temperature viscosity and increases meltability, moldability, bending workability, and Young's modulus. Furthermore, Li ₂ O has a large effect of increasing the compressive stress value among alkali metal oxides. However, in a glass system containing 7% or more of Na ₂ O, if the Li ₂ O content is extremely increased, the compressive stress is rather increased. The value tends to decrease. Therefore, the content of Li ₂ O is preferably 0-10%, 0-9%, 0-8%, 0-7%, 0-6%, 0-5%, 0-4%, 0-3. %, 0-2%, 0-1.7%, 0-1.5%, 0-1%, 0-1%, 0-0.5%, 0-0.3%, 0-0. 1%, in particular 0-0.05%. If the content of Li ₂ O is too large, the liquid phase viscosity is lowered and the glass tends to be devitrified. In addition, the thermal expansion coefficient is too high, and the thermal shock resistance is lowered. It becomes difficult to match the thermal expansion coefficient of Furthermore, the low-temperature viscosity is excessively decreased, stress relaxation is likely to occur, and the compressive stress value may be decreased.

  MgO is a component that lowers the viscosity at high temperature, increases meltability and moldability, and increases the strain point and Young's modulus. Among alkaline earth metal oxides, MgO is a component that has a large effect of improving ion exchange performance. is there. Therefore, the preferable lower limit range of MgO is 0% or more, 0.1% or more, 0.5% or more, 1% or more, 1.5% or more, and particularly 2% or more. However, when there is too much content of MgO, a density and a thermal expansion coefficient will become high easily, and it will become easy to devitrify glass. In particular, when an alumina molded refractory is used to form a flat plate by the overflow downdraw method, spinel devitrified crystals are likely to precipitate at the interface with the alumina molded refractory. Therefore, the preferable upper limit range of MgO is 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, particularly 3% or less.

  Compared with other components, CaO has a large effect of lowering the high temperature viscosity and improving the meltability and moldability, and increasing the strain point and Young's modulus without deteriorating devitrification resistance. However, if the content of CaO is too large, the density and thermal expansion coefficient become high, the component balance of the glass composition is lacking, the glass tends to devitrify, ion exchange performance decreases, It becomes easy to deteriorate an exchange solution. Therefore, the CaO content is preferably 0-6%, 0-5%, 0-4%, 0-3.5%, 0-3%, 0-2%, 0-1%, 0-1 %, Especially 0-0.5%.

  SrO is a component that lowers the viscosity at high temperature to increase meltability and moldability, and increases the strain point and Young's modulus. However, if its content is too large, the ion exchange reaction tends to be inhibited. As a result, the density and the coefficient of thermal expansion increase, and the glass tends to devitrify. Therefore, the content of SrO is preferably 0 to 2%, 0 to 1.5%, 0 to 1%, 0 to 0.5%, 0 to 0.1%, particularly less than 0 to 0.1%. is there.

  BaO is a component that lowers the high-temperature viscosity to increase the meltability and moldability, and increases the strain point and Young's modulus. However, when there is too much content of BaO, an ion exchange reaction will become easy to be inhibited, and also a density and a thermal expansion coefficient will become high, or glass will become devitrified easily. Therefore, the content of BaO is preferably 0 to 6%, 0 to 3%, 0 to 1.5%, 0 to 1%, 0 to 0.5%, 0 to 0.1%, particularly 0 to 0. Less than 1%.

TiO ₂ is a component that enhances ion exchange performance and a component that lowers the high-temperature viscosity. However, if its content is too large, the glass tends to be colored or devitrified. Therefore, the content of TiO ₂ is preferably 0 to 4.5%, 0 to 0.5%, particularly 0 to 0.3%.

ZrO ₂ is a component that remarkably improves the ion exchange performance, and is a component that increases the viscosity and strain point near the liquid phase viscosity. However, if its content is too large, the devitrification resistance may be significantly reduced. There is also a possibility that the density becomes too high. Therefore, the content of ZrO ₂ is preferably 0 to 5%, 0 to 4%, 0 to 3%, particularly 0.001 to 2%.

  ZnO is a component that enhances the ion exchange performance, and is a component that is particularly effective in increasing the compressive stress value. Moreover, it is a component which reduces high temperature viscosity, without reducing low temperature viscosity. However, when the content of ZnO is too large, the glass tends to undergo phase separation, the devitrification resistance decreases, the density increases, or the thickness of the compressive stress layer decreases. Therefore, the content of ZnO is preferably 0 to 6%, 0 to 5%, 0 to 3%, particularly 0 to 1%.

P ₂ O ₅ is a component that enhances the ion exchange performance, and in particular, is a component that increases the thickness of the compressive stress layer. However, when the content of P ₂ O ₅ is too large, or glass phase separation, the water resistance tends to decrease. Therefore, the content of P ₂ O ₅ is preferably 0 to 10%, 0 to 3%, 0 to 1%, particularly 0 to 0.5%.

SnO ₂ has an effect of improving ion exchange performance. Therefore, the content of SnO ₂ is preferably 0 to 3%, 0.01 to 3%, 0.05 to 3%, 0.1 to 3%, particularly 0.2 to 3%.

The content of Fe ₂ O ₃ is preferably less than 1000 ppm (less than 0.1%), less than 800 ppm, less than 600 ppm, less than 400 ppm, especially less than 300 ppm. Further, the Fe ₂ O ₃ content is regulated within the above range, and the molar ratio Fe ₂ O ₃ / (Fe ₂ O ₃ + SnO ₂ ) is set to 0.8 or more, 0.9 or more, particularly 0.95 or more. It is preferable to regulate. In this way, the transmittance at a plate thickness of 1 mm and a wavelength of 400 to 770 nm can be easily improved.

Rare earth oxides such as Nd ₂ O ₃ and La ₂ O ₃ are components that increase the Young's modulus. However, the cost of the raw material itself is high, and when it is added in a large amount, the devitrification resistance tends to be lowered. Therefore, the total content of rare earth oxides is preferably 3% or less, 2% or less, 1% or less, 0.5% or less, and particularly preferably 0.1% or less.

As a fining agent, one or two or more selected from the group of SO ₃ , Cl and CeO ₂ (preferably a group of Cl and SO ₃ ) may be added in an amount of 0 to 3%.

From the viewpoint of simultaneously enjoying the clarification effect and the effect of improving the ion exchange performance, the content of SnO ₂ + SO ₃ + Cl is 0.01 to 3%, 0.05 to 3%, 0.1 to 3%, particularly 0.2. ~ 3% is preferred. “SnO ₂ + SO ₃ + Cl” is the total amount of SnO ₂ , Cl and SO ₃ .

From environmental considerations, it is preferable that substantially no As ₂ O ₃ , Sb ₂ O ₃ , PbO and F are contained. Moreover, environmental considerations, it is also preferable to contain substantially no Bi ₂ O _3. “Substantially free of” means that it does not actively introduce an explicit component as a glass component, but allows it to be mixed in at an impurity level. Specifically, the explicit content is 0. . Refers to less than 05%.

In the tempered glass according to the present invention, it is possible to appropriately select a suitable content range of each component to obtain a suitable glass composition range. Among them, particularly preferable glass composition ranges are as follows.
(1) as a glass composition, in _mass%, containing _{SiO 2 45~75%, Al 2 O} 3 0~30%, Na 2 O 5~25%, the K 2 O 0%
(2) as a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 10~28%, B 2 O 3 0~10%, Li 2 O 1~10%, Na 2 O 8~20 _%, containing K 2 O 0%.

  It is preferable that the glass for reinforcement | strengthening which concerns on this invention (a base material glass and a tempered glass are the same) has the following physical property, for example.

Density is preferably 2.6 g / cm ³ or less, 2.55 g / cm ³ or less, 2.50 g / cm ³ or less, 2.48 g / cm ³ or less, 2.46 g / cm ³ or less, in particular 2.45 g / cm ³ or less. The smaller the density, the lighter the tempered glass. In addition, the content of SiO ₂ , B ₂ O ₃ , P ₂ O _{5 in} the glass composition is increased, or the content of alkali metal oxide, alkaline earth metal oxide, ZnO, ZrO ₂ , TiO ₂ is decreased. As a result, the density tends to decrease.

The thermal expansion coefficient is preferably 60 to 110 × 10 ⁻⁷ / ° C., 70 to 110 × 10 ⁻⁷ / ° C., 75 to 107 × 10 ⁻⁷ / ° C., particularly 80 to 107 × 10 ⁻⁷ / ° C. When the thermal expansion coefficient is within the above range, it becomes easy to match the thermal expansion coefficient of the peripheral member such as metal and organic adhesive, and the peripheral member can be prevented from peeling off. Increasing the content of alkali metal oxides and alkaline earth metal oxides in the glass composition increases the thermal expansion coefficient, conversely reducing the content of alkali metal oxides and alkaline earth metal oxides. If it does, a thermal expansion coefficient will become low.

The annealing point is preferably 700 ° C or lower, 680 ° C or lower, 660 ° C or lower, 640 ° C or lower, 620 ° C or lower, 600 ° C or lower, 580 ° C or lower, 560 ° C or lower, 540 ° C or lower, 520 ° C or lower, especially 500 ° C. It is as follows. If the annealing point is regulated within the above range, the bending workability can be improved and the production efficiency of the tempered glass having a bent portion can be increased. In addition, if the content of B ₂ O ₃ and alkali metal oxide in the glass composition is increased, the annealing point is likely to be lowered, and conversely, if the content of SiO ₂ and Al ₂ O ₃ is increased, the cooling is performed slowly. The point is likely to rise.

The softening point is preferably 1000 ° C or lower, 980 ° C or lower, 960 ° C or lower, 940 ° C or lower, 920 ° C or lower, 900 ° C or lower, 880 ° C or lower, 860 ° C or lower, 840 ° C or lower, 820 ° C or lower, 800 ° C or lower, It is 780 degrees C or less, 760 degrees C or less, 740 degrees C or less, 720 degrees C or less, especially 700 degrees C or less. As the softening point is lower, bending can be performed at a lower temperature. As a result, the slow cooling time immediately after bending and the cooling time can be shortened. Also, the lower the softening point, the less the burden on the mold when press molding. The deterioration of a mold is often caused by a reaction between a metal material used for the mold and oxygen in the atmosphere, that is, an oxidation reaction. When such an oxidation reaction occurs, a reaction product may be formed on the mold surface, and it may not be possible to press-mold into a predetermined shape. Further, when an oxidation reaction occurs, ions in the glass may be reduced and foaming may occur. The degree of the oxidation reaction varies depending on the press molding temperature and the softening point, and the lower the press molding temperature and the softening point, the more the oxidation reaction can be suppressed. In addition, if the content of B ₂ O ₃ and the alkali metal oxide in the glass composition is increased, the softening point tends to be lowered, and conversely, if the content of SiO ₂ and Al ₂ O ₃ is increased, the softening point is increased. It becomes easy to rise.

The temperature at 10 ^4.0 dPa · s is preferably 1400 ° C. or lower, 1350 ° C. or lower, 1300 ° C. or lower, 1250 ° C. or lower, 1200 ° C. or lower, 1150 ° C. or lower, 1100 ° C. or lower, 1050 ° C. or lower, particularly 1000 ° C. or lower. is there. As the temperature at 10 ^4.0 dPa · s is lower, the burden on the molded refractory is reduced, the life of the molded refractory is extended, and as a result, the manufacturing cost of the tempered glass is easily reduced. Here, “temperature at 10 ^4.0 dPa · s” can be measured by, for example, a platinum ball pulling method. The temperature at 10 ^4.0 dPa · s corresponds to the molding temperature. Also, if the content of alkali metal oxide, alkaline earth metal oxide, ZnO, B ₂ O ₃ , TiO _{2 in} the glass composition is increased or the content of SiO ₂ , Al ₂ O ₃ is reduced, The temperature at 10 ^4.0 dPa · s tends to decrease.

The temperature at 10 ^2.5 dPa · s is preferably 1700 ° C or lower, 1680 ° C or lower, 1650 ° C or lower, 1600 ° C or lower, 1580 ° C or lower, 1550 ° C or lower, 1450 ° C or lower, 1400 ° C or lower, 1350 ° C or lower, especially It is 1300 degrees C or less. The lower the temperature at 10 ^2.5 dPa · s, the lower the temperature melting becomes possible, and the burden on glass production equipment such as a melting kiln is reduced, and the bubble quality is easily improved. That is, the lower the temperature at 10 ^2.5 dPa · s, the easier it is to reduce the manufacturing cost of tempered glass. Here, “temperature at 10 ^2.5 dPa · s” can be measured, for example, by a platinum ball pulling method. The temperature at 10 ^2.5 dPa · s corresponds to the melting temperature. Also, if the content of alkali metal oxide, alkaline earth metal oxide, ZnO, B ₂ O ₃ , TiO _{2 in} the glass composition is increased or the content of SiO ₂ , Al ₂ O ₃ is reduced, The temperature at 10 ^2.5 dPa · s tends to decrease.

The liquidus temperature is preferably 1300 ° C. or lower, 1280 ° C. or lower, 1250 ° C. or lower, 1230 ° C. or lower, 1200 ° C. or lower, 1170 ° C. or lower, 1100 ° C. or lower, 1070 ° C. or lower, 1050 ° C. or lower, 1020 ° C. or lower. In particular, it is 1000 ° C. or less. The lower the liquidus temperature, the better the devitrification resistance and the moldability. In addition, increase the content of Na ₂ O, K ₂ O, B ₂ O _{3 in} the glass composition or decrease the content of Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ , ZrO _2. In this case, the liquidus temperature tends to decrease.

Liquidus viscosity, preferably of ¹⁰ 4.0 dPa · s or ^{more, 10} 4.4 dPa · s or ^{more, 10} 4.8 dPa · s or ^{more, 10} 5.0 dPa · s or ^more, 10 5.3 dPa · s Above, 10 ^5.5 dPa · s or more, 10 ^5.7 dPa · s or more, 10 ^5.8 dPa · s or more, particularly 10 ^6.0 dPa · s or more. The higher the liquidus viscosity, the better the devitrification resistance and moldability. If the content of Na ₂ O, K ₂ O in the glass composition is increased or the content of Al ₂ O ₃ , Li ₂ O, MgO, ZnO, TiO ₂ , ZrO ₂ is reduced, the liquidus viscosity Tends to be high.

  The Young's modulus is preferably 65 GPa or more, 69 GPa or more, 71 GPa or more, 75 GPa or more, particularly 77 GPa or more. As the Young's modulus is higher, the tempered glass is more difficult to bend, and when used for a touch panel display or the like, even if the surface of the tempered glass is strongly pressed with a pen or the like, the deformation amount of the tempered glass becomes smaller. As a result, it becomes easy to prevent the situation where the tempered glass comes into contact with the liquid crystal element and a display defect occurs. Also, the higher the Young's modulus, the smaller the amount of deformation with respect to the stress generated during the ion exchange process, so it becomes easier to reduce the dimensional change before and after the ion exchange process.

  In the method for producing tempered glass according to the present invention, the base glass is heat-treated at a temperature equal to or higher than the base glass (annealing point−50 ° C.), the base glass is bent, and then from the slow cooling point of the base glass. The step of obtaining a glass for strengthening having a bent portion by cooling the temperature range up to the strain point, and the base glass after heat-treating the base glass to a temperature higher than the base glass (annealing point −50 ° C.) Cooling the temperature range from the annealing point to the strain point of the glass to obtain a flat plate-shaped strengthening glass, and the heat history of the flat plate-shaped strengthening glass is obtained from the reinforcing glass having a bending portion. A tempered glass having a bent portion and a tempered glass having a flat shape are respectively produced after making the thermal history of the bent portion substantially the same. The technical features of the method for producing tempered glass of the present invention are described above. Therefore, detailed description is omitted here.

  The method for producing tempered glass of the present invention is a method for producing tempered glass in which a tempered glass having a bent part is immersed in an ion exchange solution to obtain a tempered glass having a bent part. It has the process of managing the stress state of a bending part on the basis of the stress state of flat plate-shaped tempered glass. The technical features of the method for producing tempered glass of the present invention are described above. Therefore, detailed description is omitted here.

  The tempered glass of the present invention is produced by the method for producing tempered glass described above. Further, the tempered glass of the present invention has a bending portion and a compressive stress layer on the surface of the bending portion, the compressive stress value of the compressive stress layer in the bending portion is 50 MPa or more, and the thickness of the compressive stress layer in the bending portion is It is 10 μm or more. The technical characteristics (preferable characteristics, preferable component ranges, etc.) of the tempered glass of the present invention have already been described in the explanation column of the method for producing the tempered glass of the present invention. Therefore, detailed description of the technical features of the tempered glass of the present invention is omitted. In addition, the compressive stress value and thickness of the compressive stress layer corresponding to the bent portion can be estimated by the above method.

  Hereinafter, based on an Example, this invention is demonstrated in detail. However, the following examples are merely illustrative. The present invention is not limited to the following examples.

  Table 1 shows examples (Nos. 1 to 15) of the present invention.

  Each sample was produced as follows. First, glass raw materials were prepared so as to have the glass composition in the table, and were melted at 1580 ° C. for 8 hours using a platinum pot. Thereafter, the molten glass was poured onto a carbon plate and formed into a flat plate shape. Various characteristics were evaluated about the obtained glass.

  The density ρ is a value measured by the well-known Archimedes method.

  The thermal expansion coefficient α is a value obtained by measuring an average thermal expansion coefficient in a temperature range of 25 to 380 ° C. using a dilatometer.

  The strain point Ps and the annealing point Ta are values measured based on the method of ASTM C336.

  The softening point Ts is a value measured based on the method of ASTM C338.

The temperature at a high temperature viscosity of 10 ^4.0 dPa · s, 10 ^3.0 dPa · s, and 10 ^2.5 dPa · s is a value measured by a platinum ball pulling method.

  The liquid phase temperature TL passes through a standard sieve 30 mesh (a sieve opening of 500 μm), and glass powder remaining in a 50 mesh (a sieve opening of 300 μm) is put in a platinum boat, and then held in a temperature gradient furnace for 24 hours. This is a value obtained by measuring the temperature at which crystals are deposited.

  The liquid phase viscosity log ηTL is a value obtained by measuring the viscosity of the glass at the liquid phase temperature by a platinum ball pulling method.

  The Young's modulus E is a value measured by a known resonance method.

Subsequently, after both surfaces of each sample were subjected to optical polishing, ion exchange treatment was performed by immersing in KNO ₃ molten salt (new KNO ₃ molten salt) at 430 ° C. for 4 hours. The surface of each sample was washed after the ion exchange treatment. Subsequently, the compressive stress value CS and the thickness DOL of the compressive stress layer on the surface were calculated from the number of interference fringes observed using a surface stress meter (FSM-6000 manufactured by Toshiba Corporation) and the interval therebetween. In the calculation, the refractive index of each sample was set to 1.50 and the optical elastic constant was set to 30 [(nm / cm) / MPa].

  Next, sample No. About the material of 3, after shape | molding in the flat plate shape by the overflow downdraw method, it cut | disconnected to the predetermined size, and obtained the some base material glass. The average surface roughness Ra of the base glass was 2 mm or less.

  Furthermore, after the base glass is heat-treated at the annealing point temperature of the base glass and the base glass is bent, the temperature range from the annealing point to the strain point of the base glass is an average of 8 ° C./min. By cooling at a cooling rate, tempered glasses having bent portions as shown in FIGS. 1A, 3 and 4 were obtained. The bending process was performed by press molding using a mullite mold. Furthermore, after heat-treating another base glass at the annealing point temperature of the base glass, the temperature range from the annealing point to the strain point of the base glass is cooled at an average cooling rate of 8 ° C./min. A flat glass for strengthening was obtained. That is, substantially the same thermal history as that of the bent portion of the reinforcing glass having a bent portion was applied to the entire flat plate-shaped reinforcing glass.

Subsequently, the tempering glass having the bent portion and the flat tempering glass are immersed in 430 ° C. KNO ₃ molten salt (new KNO ₃ molten salt) in the same ion exchange tank for 4 hours to bend. A tempered glass having a portion and a flat tempered glass were obtained at the same time. When the compressive stress value CS and the thickness DOL of the compressive stress layer were measured for the tempered glass having a flat plate shape, the compressive stress value CS was 856 MPa, and the thickness of the compressive stress layer was 28 μm. Therefore, it can be estimated that the compressive stress value CS of the compressive stress layer of the bent portion is 856 MPa, and the thickness of the compressive stress layer of the bent portion is 28 μm.

For reference, after flat plate-shaped tempered glass before bending is immersed in 430 ° C. KNO ₃ molten salt (new KNO ₃ molten salt) for 4 hours to obtain flat tempered glass, When the compressive stress value CS and the thickness DOL of the compressive stress layer were measured, the compressive stress value CS was 735 MPa, and the thickness of the compressive stress layer was 33 μm.

  In the above experiment, Sample No. No. 3 material was used. Similar experiments can be performed with 1, 2, 4 to 15 materials.

  The tempered glass of the present invention is suitable as a touch glass for a touch panel display, a mobile phone, a digital camera, a PDA, or a substrate for a touch panel display. In addition to these uses, the tempered glass of the present invention is used for applications requiring high design properties, such as window glass, flat panel display substrates, solar cell cover glasses, solid-state image sensor cover glasses, and dishes. The application of can be expected.

1, 4, 7, 14, 17, 20, 23 ... bent portions 2, 5, 8, 15, 18, 21, 24 ... flat plate portions 3, 6, 9, 11, 13, 16, 19, 22, 25 ... End faces 10, 12, 26 ... Curved portion 27 ... Ion exchange tank 28 ... Ion exchange solution (KNO ₃ solution)
29, 30 ... Basket 31 ... Flat glass for strengthening 32 ... Glass for strengthening with bent part

Claims (19)

  Tempering characterized by having a step of simultaneously obtaining a tempered glass having a bent portion and a tempered glass having a flat shape by immersing the tempered glass having a bent portion and a flat shape tempered glass in the same ion exchange solution. Glass manufacturing method.   2. The method for producing tempered glass according to claim 1, wherein the flat-shaped tempering glass has substantially the same thermal history as that of the tempered glass having a bent part. 3.   After the base glass is heat-treated at a temperature not lower than the base glass (slow cooling point-50 ° C.) and the base glass is bent, the temperature range from the slow cooling point to the strain point of the base glass is cooled. The method for producing a tempered glass according to claim 1, wherein a tempered glass having a bent portion is obtained.   After heat-treating the base glass to a temperature equal to or higher than that of the base glass (annealing point−50 ° C.), the temperature range from the annealing point to the strain point of the base glass is cooled to obtain a flat plate-shaped reinforcing glass. The manufacturing method of the tempered glass as described in any one of Claims 1-3 characterized by the above-mentioned.   The method for producing tempered glass according to claim 3 or 4, wherein the base glass has a flat plate shape.   After heat-treating the base glass, the temperature range from the annealing point to the strain point is cooled at a cooling rate of 0.2 ° C / min to 200 ° C / min. The manufacturing method of the tempered glass of one term.   The warpage amount of flat-plate-shaped tempered glass is 1 mm or less, The manufacturing method of tempered glass as described in any one of Claims 1-6 characterized by the above-mentioned.   The flat glass-shaped reinforcing glass is immersed in an ion exchange solution so that the compressive stress value of the compressive stress layer is 50 MPa or more and the thickness of the compressive stress layer is 10 μm or more. The manufacturing method of the tempered glass of one term. Wherein the reinforcing glass is a glass composition including, in _{mass%, SiO 2 45~75%, Al} 2 O 3 0~30%, Na 2 O 5~25%, in that it contains K 2 O 0% The manufacturing method of the tempered glass as described in any one of Claims 1-8. Reinforcing glass, as a glass composition, in _{mass%, SiO 2 45~75%, Al} 2 O 3 10~28%, B 2 O 3 0~10%, Li 2 O 0~10%, Na 2 O 8 method for producing a tempered glass according to any one of claims 1-9, characterized in that it contains _{~20%, K 2 O 0~10%} .   The method for producing tempered glass according to any one of claims 1 to 10, wherein the tempered glass has a softening point of 1050 ° C or lower. The method for producing tempered glass according to claim 1, wherein the tempered glass has a thermal expansion coefficient of 60 to 110 × 10 ⁻⁷ / ° C. The method for producing tempered glass according to any one of claims 1 to 12, wherein a liquid phase viscosity of the tempered glass is 10 ^4.0 dPa · s or more.   After the base glass is heat-treated at a temperature not lower than the base glass (slow cooling point-50 ° C.) and the base glass is bent, the temperature range from the slow cooling point to the strain point of the base glass is cooled. From the step of obtaining a glass for strengthening having a bent portion, and after heat-treating the base glass to a temperature equal to or higher than (annealing point-50 ° C.) of the base glass, from the annealing point to the strain point of the base glass. A step of obtaining a flat plate-shaped reinforcing glass by cooling the temperature region, and bending the heat history of the flat plate-shaped reinforcing glass substantially the same as the heat history of the bent portion of the reinforcing glass. The manufacturing method of the tempered glass characterized by producing the tempered glass which has a part, and flat plate-shaped tempered glass, respectively.   A method for producing a tempered glass in which a tempered glass having a bent part is immersed in an ion exchange solution to obtain a tempered glass having a bent part, and the stress state of the bent part of the tempered glass having the bent part is strengthened in a flat plate shape. The manufacturing method of the tempered glass characterized by having the process managed on the basis of the stress state of glass.   A tempered glass produced by the method for producing a tempered glass according to any one of claims 1 to 15.   It has a bending part and has a compressive stress layer on the surface of the bending part, the compressive stress value of the compressive stress layer in the bending part is 50 MPa or more, and the thickness of the compressive stress layer in the bending part is 10 μm or more. Tempered glass.   The tempered glass according to claim 16 or 17, which is used for a cover glass of a touch panel display.   The tempered glass according to claim 16 or 17, which is used for a cover glass of a mobile phone.