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CN-116282908-B - Chemically strengthened glass, method for producing same, and glass for chemical strengthening

CN116282908BCN 116282908 BCN116282908 BCN 116282908BCN-116282908-B

Abstract

The present invention relates to a chemically strengthened glass, a method for producing the same, and a glass for chemical strengthening. A chemically strengthened glass having a plate-shaped, chemically strengthened glass with a compressive stress layer on the surface of the glass, wherein the compressive stress value (CS 0 ) on the surface of the glass is 500MPa or more, the plate thickness (t) is 400 [ mu ] m or more, the depth of layer of compressive stress (DOL) is (t X0.15) mu ] m or more, the compressive stress value (CS 1 ) at the position of 1/4 of the depth of DOL from the surface of the glass and the compressive stress value (CS 2 ) at the position of 1/2 of the depth of DOL from the surface of the glass are each 50MPa or more, m 1 represented by { m 1 ＝(CS 1 -CS 2 )/(DOL/4-DOL/2) } is-1.5 MPa/mu.m or more, m 2 represented by { m 2 ＝CS 2 /(DOL/2-DOL) } is 0 MPa/mu.m or less, and m 2 is less than m 1 .

Inventors

  • IMAKITA KENJI
  • MURAYAMA HIROSHI

Assignees

  • ＡＧＣ株式会社

Dates

Publication Date
20260508
Application Date
20180625
Priority Date
20170628

Claims (11)

  1. 1. A chemically strengthened glass having a plate-like shape and a compressive stress layer on the surface of the glass, wherein, The compressive stress value CS 0 of the glass surface of the chemically strengthened glass is more than 500MPa, The thickness t of the chemically strengthened glass is 400 μm or more, The depth of the compressive stress layer DOL of the chemically strengthened glass is (t multiplied by 0.15) mu m or more, The compressive stress value CS 1 at a position 1/4 of the DOL from the glass surface is 50MPa or more, The compressive stress value CS 2 at a position 1/2 of the DOL from the glass surface is 50MPa or more, M 1 represented by the following formula is 0.5 MPa/. Mu.m or less, m 2 represented by the following formula is 0 MPa/. Mu.m or less, m 1 ＝(CS 1 -CS 2 )/(DOL/4-DOL/2) m 2 ＝CS 2 /(DOL/2-DOL), M 3 represented by the following formula is related to the compressive stress value CS 3 at a position having a depth of 2.5 μm from the glass surface and is 150MPa/μm or more, m 3 ＝(CS 0 -CS 3 )/2.5 Expressed as mass percent on an oxide basis, the basic composition of the chemically strengthened glass contains: 55-70% of SiO 2 , 15-28% Of Al 2 O 3 , 0-10% Of B 2 O 3 , 2-8% Of Li 2 O, 1-8% Of Na 2 O, 0-9% Of K 2 O, 0% -5% (MgO+CaO+SrO+BaO), and 0% -3% (ZrO 2 +TiO 2 ).
  2. 2. A chemically strengthened glass having a plate-like shape and a compressive stress layer on the surface of the glass, wherein, The compressive stress value CS 0 of the glass surface of the chemically strengthened glass is more than 500MPa, The depth of the compressive stress layer DOL of the chemically strengthened glass is more than 100 mu m, The compressive stress value CS 1 at a position 1/4 of the DOL from the glass surface is 50MPa or more, The compressive stress value CS 2 at a position 1/2 of the DOL from the glass surface is 50MPa or more, M 1 represented by the following formula is 0.5 MPa/. Mu.m or less, m 2 represented by the following formula is 0 MPa/. Mu.m or less, m 1 ＝(CS 1 -CS 2 )/(DOL/4-DOL/2) m 2 ＝CS 2 /(DOL/2-DOL), M 3 represented by the following formula is related to the compressive stress value CS 3 at a position having a depth of 2.5 μm from the glass surface and is 150MPa/μm or more, m 3 ＝(CS 0 -CS 3 )/2.5 Expressed as mass percent on an oxide basis, the basic composition of the chemically strengthened glass contains: 55-70% of SiO 2 , 15-28% Of Al 2 O 3 , 0-10% Of B 2 O 3 , 2-8% Of Li 2 O, 1-8% Of Na 2 O, 0-9% Of K 2 O, 0% -5% (MgO+CaO+SrO+BaO), and 0% -3% (ZrO 2 +TiO 2 ).
  3. 3. The chemically strengthened glass according to claim 1 or 2, wherein the maximum depth of the chemically strengthened glass at a compressive stress value of 50MPa or more is (0.55 x DOL) μm or more in relation to the DOL.
  4. 4. The chemically strengthened glass according to claim 1 or 2, wherein m 3 is 180MPa/μm or more.
  5. 5. The chemically strengthened glass according to claim 1 or 2, wherein m 3 is 200MPa/μm or more.
  6. 6. The chemically strengthened glass according to claim 1 or 2, wherein m 3 is 220MPa/μm or more.
  7. 7. The chemically strengthened glass according to claim 1 or 2, wherein m 1 is-0.2 MPa/μm or less.
  8. 8. The chemically strengthened glass according to claim 1 or 2, wherein a ratio (m 1 /m 2 ) of the m 1 to the m 2 is 0.1 or more.
  9. 9. The chemically strengthened glass of claim 1 or 2, wherein the chemically strengthened glass has an internal tensile stress value of less than 100MPa.
  10. 10. The chemically strengthened glass according to claim 1 or 2, wherein the basic composition of the chemically strengthened glass, expressed as mass percent on an oxide basis, contains: MgO in an amount of 0% to 5%, and 0.5% -5% Of CaO.
  11. 11. A method for producing a chemically strengthened glass according to any one of claims 1 to 10, comprising the steps of: Ion-exchange is performed by bringing a chemically strengthened glass containing Li 2 O into contact with a metal salt containing Na ions, Then, ion exchange is performed by contact with a metal salt containing Li ions, wherein the Na/Li molar ratio in the metal salt containing Li ions is 0.3 to 60, Then, ion exchange is performed by contact with a metal salt containing K ions, The glass for chemical strengthening contains 55-70% by mass of SiO 2 , 15-28% Of Al 2 O 3 , 0-5% Of B 2 O 3 , 2-8% Of Li 2 O, 1-8% Of Na 2 O, 0-9% Of K 2 O, 0% -5% MgO, 0.5-5% Of CaO, 0.6% -5% (MgO+CaO+SrO+BaO), and 0% -3% (ZrO 2 +TiO 2 ).

Description

Chemically strengthened glass, method for producing same, and glass for chemical strengthening The application relates to a divisional application of a Chinese patent application with the application date of 2018, 6, 25 and the application number of 201880042555.9. Technical Field The present invention relates to chemically strengthened glass. Background Chemically strengthened glass is used for protective glass of portable terminals and the like. The chemically strengthened glass is a glass in which a compressive stress layer is formed on the surface of the glass by bringing the glass into contact with a molten salt containing metal ions such as alkali metal ions to exchange ions between the metal ions in the glass and the metal ions in the molten salt. The strength of chemically strengthened glass is highly dependent on the stress distribution expressed by the compressive stress value with the depth from the glass surface as a variable. The cover glass of a mobile terminal or the like may break when bent by an external force. The starting point for the fracture in this case is located at the glass surface, and the micro-cracks of the glass surface propagate until fracture. Therefore, it is considered that by increasing the compressive stress value of the glass surface, propagation of micro cracks can be suppressed and breakage is less likely to occur. The cover glass of a mobile terminal or the like may be broken by the protrusions when it falls onto asphalt or sand. The starting point of the fracture in this case is located deeper than the glass surface. Therefore, it is considered that the compressive stress layer is formed by increasing the depth of the compressive stress layer to a deeper portion of the glass, and thus the glass is less likely to be broken. On the other hand, when a compressive stress layer is formed on the surface of glass, a tensile stress layer is inevitably formed inside the glass. When the internal tensile stress is large, the chemically strengthened glass is broken strongly, and fragments are likely to scatter. Therefore, a method of increasing the surface compressive stress and the depth of the compressive stress layer while suppressing the internal tensile stress value has been studied. Patent document 1 describes that a chemically strengthened glass having a compressive stress layer depth of 90 μm or more is obtained by one or two ion exchange treatments. In addition, typical stress distribution in the case where ion exchange treatment is performed twice is illustrated. The distribution is composed of two straight lines, one is a straight line representing the stress distribution from the glass surface to the position X located at a certain depth, and the other is a straight line representing the stress distribution from the position X to the position where the stress is zero (patent document 1, fig. 8). It is considered that if such a stress distribution is used, the surface compressive stress is increased, and the depth of the compressive stress layer is increased, while the internal tensile stress value is suppressed. Prior art literature Patent literature Patent document 1 International publication No. 2015/127483 Disclosure of Invention Problems to be solved by the invention However, even the glass described in patent document 1 may have insufficient strength when dropped onto sand or asphalt (hereinafter, sometimes referred to as "asphalt drop strength"). The purpose of the present invention is to provide a chemically strengthened glass which has high asphalt falling strength and is less likely to scatter fragments during crushing. Means for solving the problems The present inventors have found from the following studies and experiments that, in order to improve the asphalt falling strength, it is important that the maximum depth at which a compressive stress value of 50MPa is obtained is greater than the depth DOL of the compressive stress layer. When the glass plate falls onto asphalt, microcracks are generated inside the glass plate due to the protrusions on the asphalt surface. When the generated micro cracks propagate and grow, the glass plate breaks. The propagation of the microcracks can be suppressed by a compressive stress of about 50 MPa. Therefore, if the maximum depth at which a compressive stress value of 50MPa is obtained is large, it is considered that breakage is less likely to occur even if microcracks occur inside the glass due to relatively large protrusions. Table 1 shows the results of the chemical strengthening of a float glass sheet containing, in terms of mass percentage based on oxides, 60.7% of SiO 2, 16.8% of Al 2O3, 15.6% of Na 2 O, 1.2% of K 2 O, 5.3% of MgO and 0.4% of ZrO 2, and the asphalt falling strength test described later. In this experiment, the tendency was observed that the larger the maximum depth at which a compressive stress value of 50MPa was obtained, the more resistant it was to dropping from a high position. TABLE 1 Sample