Chemically strengthened glass and method for manufacturing chemically strengthened glass
Abstract
One embodiment of the present invention is a chemically strengthened glass having a thickness t of 2 mm or less, and a compressive stress value (CS) at a depth of 90 µm from the glass surface.90) is 25 MPa or more, and in a destructive test by an indenter indentation test under the condition that a load in the range of 5 kgf to 10 kgf is maintained for 15 seconds with a square pyramid diamond indenter having an indenter angle of 60 °, the size of 25 mm × 25 mm The number of fragments generated within is 20 or less, and it is a glass plate having a parent composition of the chemically strengthened glass, and is slowly cooled from a temperature T°C 30°C to 50°C higher than the glass transition point to (T-300)°C at 0.5°C/min. For a glass plate with a thickness of 1 mm, KNO3, NaNO3, or KNO3and NaNO3It relates to chemically strengthened glass having a compressive stress layer depth (DOL) of 50 µm or more when an ion exchange treatment is performed for 1 hour with molten salt at 400°C containing a mixed salt of

Term
10.3 yearsto projected expiry
Projected expiry 19 January 2037, counted from filing; an application has no term until it is granted.
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25 claims: 4 independent, 21 dependent
- 1두께 t가 2mm 이하인 화학 강화 유리이며, 유리 표면으로부터 90㎛의 깊이 부분의 압축 응력값(CS 90 )이 25MPa 이상이며, 대면각의 압자 각도가 60°인 사각뿔 다이아몬드 압자로 5kgf 내지 10kgf의 범위에서의 하중을 15초간 유지하는 조건에서의 압자 압입 시험에 의한 파괴 시험에 있어서, 25mm×25mm의 사이즈 내에 발생하는 파편의 수가 20개 이하이고, 상기 화학 강화 유리의 모 조성을 갖는 유리판이며, 유리 전이점보다 30℃ 내지 50℃ 높은 온도 T℃로부터, (T-300)℃까지 0.5℃/분으로 서냉시킨 두께 1mm의 유리판에 대하여, KNO 3 , NaNO 3 , 또는 KNO 3 과 NaNO 3 의 혼합염을 포함하는 400℃의 용융염에 의해, 1시간의 이온 교환 처리를 행했을 때의 압축 응력층 깊이(DOL)가 50㎛ 이상이 되는 화학 강화 유리.
- 2제1항에 있어서, 상기 CS 90 과, 유리 표면으로부터 100㎛의 깊이 부분의 압축 응력값(CS 100 )을 사용하여 하기 식에 의해 산출되는 ΔCS 100 -90 (단위:MPa/㎛)이 0.4 이상인 화학 강화 유리. ΔCS 100-90 =(CS 90 -CS 100 )/(100-90)
- 3제2항에 있어서, 상기 ΔCS 100 -90 (단위:MPa/㎛)이 4.0 이하인 화학 강화 유리.
- 4제1항 내지 제3항 중 어느 한 항에 있어서, DOL로부터 20㎛ 유리 표면측의 깊이에 있어서의 압축 응력값 CS DOL -20 을 사용하여 하기 식에 의해 산출되는 ΔCS DOL -20 (단위:MPa/㎛)이 0.4 이상인 화학 강화 유리. ΔCS DOL-20 =CS DOL-20 /20
- 5제4항에 있어서, 상기 ΔCS DOL-20 (단위:MPa/㎛)이 4.0 이하인 화학 강화 유리.
- 6제1항 내지 제5항 중 어느 한 항에 있어서, 다이아몬드 압자(대면각의 압자 각도:110°)를 하중 0.5Kgf로 하여 15초간 누름으로써, 유리 표면을 흠집낸 후에, 하부 스팬 30mm, 상부 스팬 10mm, 크로스헤드 속도 0.5mm/분의 조건에서 4점 굽힘 시험을 행함으로써 얻어지는 파괴 응력값 σa(굽힘 강도, 단위: MPa)가 150MPa 이상인 화학 강화 유리.
- 7제1항 내지 제5항 중 어느 한 항에 있어서, 다이아몬드 압자(대면각의 압자 각도:110°)를 하중 2Kgf로 하여 15초간 누름으로써, 유리 표면을 흠집낸 후에, 하부 스팬 30mm, 상부 스팬 10mm, 크로스헤드 속도 0.5mm/분의 조건에서 4점 굽힘 시험을 행함으로써 얻어지는 파괴 응력값 σc(굽힘 강도, 단위: MPa)가 150MPa 이상인 화학 강화 유리.
- 8제1항 내지 제7항 중 어느 한 항에 있어서, 표면 압축 응력값이 300MPa 이상인 화학 강화 유리.
- 9제1항 내지 제8항 중 어느 한 항에 있어서, 압축 응력층 깊이(DOL)가 100㎛ 이상인 화학 강화 유리.
- 10제1항 내지 제9항 중 어느 한 항에 있어서, 상기 두께 t가 0.9mm 이하인 화학 강화 유리.
- 11제1항 내지 제10항 중 어느 한 항에 있어서, 압축 응력층의 면적 Sc(MPa·㎛)가 20000MPa·㎛ 이상인 화학 강화 유리.
- 12제1항 내지 제11항 중 어느 한 항에 있어서, 압축 응력층의 면적 Sc(MPa·㎛)를 두께 t(㎛)로 나눈 값 Sc/t(MPa)가 28MPa 이상인 화학 강화 유리.
- 13하기 식(1) 및 (2)를 충족시키는 화학 강화 유리. NM/Nh≥1.8 (1) KM/Kh≥3 (2) (여기서, NM, Nh, KM 및 Kh는, 각각 이하를 나타낸다. NM:EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 Na 이온 농도 프로파일에 있어서의 최댓값을 Na 2 O(중량%)로 환산한 값 Nh: EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 Na 이온 농도 프로파일에 있어서의 판 두께의 중심값을 Na 2 O(중량%)로 환산한 값 KM: EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 K 이온 농도 프로파일에 있어서의 최댓값을 K 2 O(중량%)로 환산한 값 Kh: EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 K 이온 농도 프로파일에 있어서의 판 두께의 중심값을 K 2 O(중량%)로 환산한 값)
- 14제13항에 있어서, 추가로 하기 식(3)을 충족시키는 화학 강화 유리. N0/Nh≥0.8 (3) (여기서, N0은, 이하를 나타낸다. N0:EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 Na 이온 농도 프로파일에 있어서의 최표면에서의 값을 Na 2 O(중량%)로 환산한 값)
- 15제13항 또는 제14항에 있어서, 추가로 하기 식(4)를 충족시키는 화학 강화 유리. N0/NM≥0.4 (4) (여기서, N0은, 이하를 나타낸다. N0:EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 Na 이온 농도 프로파일에 있어서의 최표면에서의 값을 Na 2 O(중량%)로 환산한 값)
- 16하기 식(5) 및 (6)을 충족시키는 화학 강화 유리. NM-Nh≥2.2(wt%) (5) KM-Kh≥3(wt%) (6) (여기서, NM, Nh, KM 및 Kh는, 각각 이하를 나타낸다. NM:EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 Na 이온 농도 프로파일에 있어서의 최댓값을 Na 2 O(중량%)로 환산한 값 Nh: EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 Na 이온 농도 프로파일에 있어서의 판 두께의 중심값을 Na 2 O(중량%)로 환산한 값 KM: EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 K 이온 농도 프로파일에 있어서의 최댓값을 K 2 O(중량%)로 환산한 값 Kh: EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 K 이온 농도 프로파일에 있어서의 판 두께의 중심값을 K 2 O(중량%)로 환산한 값)
- 17제16항에 있어서, 추가로 하기 식(7)을 충족시키는 화학 강화 유리. N0-Nh≥-0.4(wt%) (7) (여기서, N0은, 이하를 나타낸다. N0:EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 Na 이온 농도 프로파일에 있어서의 최표면에서의 값을 Na 2 O(중량%)로 환산한 값)
- 18제16항 또는 제17항에 있어서, 추가로 하기 식(8)을 충족시키는 화학 강화 유리. N0-NM≥-3.5(wt%) (8) (여기서, N0은, 이하를 나타낸다. N0:EPMA에 의해 측정되는 상기 화학 강화 유리의 판 두께 방향의 Na 이온 농도 프로파일에 있어서의 최표면에서의 값을 Na 2 O(중량%)로 환산한 값)
- 19제13항 내지 제18항 중 어느 한 항에 있어서, 상기 화학 강화 유리의 굽힘 강도가 400MPa 이상인 화학 강화 유리.
- 20제13항 내지 제19항 중 어느 한 항에 있어서, 상기 화학 강화 유리의 표면 압축 응력(CS)이 400MPa 이상인 화학 강화 유리.
- 21제13항 내지 제20항 중 어느 한 항에 있어서, 상기 화학 강화 유리의 압축 응력층 깊이(DOL)가 100㎛ 이상인 화학 강화 유리.
- 22제13항 내지 제21항 중 어느 한 항에 있어서, 상기 화학 강화 유리는 판 두께 t가 2mm 이하인 판 형상인 화학 강화 유리.
- 23제13항 내지 제22항 중 어느 한 항에 있어서, 상기 화학 강화 유리는, 대면각 60°의 사각뿔 다이아몬드 압자로 5kgf 내지 10kgf의 범위에서의 하중을 15초간 유지하는 조건에서의 압자 압입 시험에 의한 파괴 시험에 있어서, 25mm×25mm의 사이즈 내에 발생하는 파편의 수가 20개 이하인 화학 강화 유리.
- 24제1항 내지 제23항 중 어느 한 항에 있어서, 상기 화학 강화 유리의 모 조성이, 산화물 기준의 몰 백분율 표시로, SiO 2 를 50 내지 80%, Al 2 O 3 을 1 내지 30%, B 2 O 3 을 0 내지 5%, P 2 O 5 를 0 내지 4%, Li 2 O를 3 내지 20%, Na 2 O를 0 내지 8%, K 2 O를 0 내지 10%, MgO를 3 내지 20%, CaO를 0 내지 20%, SrO를 0 내지 20%, BaO를 0 내지 15%, ZnO를 0 내지 10%, TiO 2 를 0 내지 1%, ZrO 2 를 0 내지 8%를 함유하는 화학 강화 유리.
- 25제1항 내지 제24항 중 어느 한 항에 있어서, 유리에 적어도 2단계의 이온 교환 처리를 행하는 것을 포함하는, 화학 강화 유리의 제조 방법이며, 1단째의 이온 교환 처리에 사용되는 용융염 중의 KNO 3 농도가 60중량% 이상이고, 또한 2단째의 이온 교환 처리에 사용되는 용융염 중의 NaNO 3 농도가 5중량% 이상인, 화학 강화 유리의 제조 방법.
Independent claims25
238 paragraphs in 1 section, as filed
Chemically strengthened glass and chemically strengthened glass manufacturing method
The present invention relates to chemically strengthened glass and a method for manufacturing chemically strengthened glass.
In recent years, in order to protect the display device of mobile devices such as mobile phones, smart phones, personal digital assistants (PDAs), and tablet terminals, and to enhance the aesthetics, a cover glass made of chemically strengthened glass is used.
In particular, when a mobile device such as a smartphone is accidentally dropped, it collides with a collision object (hereinafter also referred to as an acute-angle object) having a small collision portion such as sand, and deep scratches are generated. In this state, tensile stress is generated on the surface of the glass, and scratches tend to develop, and the chance that the chemically strengthened glass as the cover glass is damaged is relatively high. Therefore, there is a demand for chemically strengthened glass that is not easily damaged even when it collides with an acute-angle object (hereinafter, also referred to as "high sharp-angle object scratch strength").
Chemically strengthened glass with a deep compressive stress layer (DOL) is considered advantageous as a glass with a high sharp-angle scratch strength. However, in order to increase production efficiency, a glass with a large ion exchange rate is required.
Here, Patent Document 1 discloses that chemically strengthened glass having a large depth of compressive stress layer (DOL) has high fracture resistance in a drop test using #180 sandpaper.
Further, Patent Document 2 discloses a lithium aluminosilicate glass having a high ion exchange rate.
Further, Patent Document 1 discloses chemically strengthened glass using both Na-K exchange in which Na ions in glass are exchanged with K ions and Li-Na exchange in which Li ions in glass are exchanged with Na ions.
<p><patcit num="0001"><text>Specification of US Patent Publication No. 2015/0259244 </text></patcit><patcit num="0002"><text>Japanese Patent Publication No. 2013-520385</text></patcit></p>
<p>However, as a result of intensive studies by the present inventors, when a mobile device such as a smartphone is accidentally dropped in a practical scene such as a road, the depth of the scratch generated on the cover glass by collision with an acute angle object such as sand is , it was found to be deeper than the depth of scratches generated in the drop test using #180 sandpaper. Therefore, in a cover glass containing chemically strengthened glass, in a practical scene, resistance to breakage due to scratches generated in a drop test using #180 sandpaper as described in Patent Document 1 is not necessarily sufficient. . In addition, in chemically strengthened glass using Na-K exchange as described in Patent Document 1, a long ion exchange treatment time such as 10 hours or more is required in order to obtain a large compressive stress layer depth such as more than 100 μm.</p><p>Moreover, although the lithium aluminosilicate glass with a fast ion exchange rate is disclosed in patent document 2, the guideline for high strength with respect to the sharp-angle flaw strength is unclear.</p><p>As described above, in the prior art, a specific method for increasing the scratch strength of an acute angle object was not clear. In order to satisfy the high acute-angle object scratch strength, a glass having a deeper compressive stress layer and a larger compressive stress value of the compressive stress layer is required. Moreover, it is requested|required at the same time that the number of fractures of glass is small and safety|security is high even if it breaks. In order to obtain such a glass, a glass with a large ion exchange rate required for chemical strengthening is desired.</p><p>Accordingly, one object of the present invention is to provide a chemically strengthened glass that is excellent in sharp-angle scratch strength, has high safety at the time of crushing, and has a fast ion exchange rate.</p><p>In addition, it is known that the cover glass leads to destruction due to surface tensile stress generated by falling or collision with a substance, and that it leads to failure due to scratches caused by collision of the surface with an acute angle object, etc. For this purpose, it is necessary to increase both the bending strength and the bending strength after being damaged by an acute angle object (hereinafter also referred to as bending strength after being damaged). Here, in order to increase both the bending strength and the bending strength after scratches, (1) introducing a compressive stress as large as possible to the outermost surface of the glass, and (2) introducing a compressive stress layer as deep as possible in the glass; Four things are necessary: (3) to introduce as much compressive stress as possible into the interior of the glass, and (4) to achieve (2) and (3) the ion exchange rate is high.</p><p>Here, in Patent Document 1, although both Na-K exchange and Li-Na exchange were used to achieve the above (1), (2) and (4), the above (3) was insufficient.</p><p>In view of the above conventional problems, one object of the present invention is to provide a chemically strengthened glass having both high bending strength and high post-damage bending strength, and a method for manufacturing the chemically strengthened glass.</p>
<p>One embodiment of the present invention is a chemically strengthened glass having a thickness t of 2 mm or less,</p><p>Compressive stress value at a depth of 90 μm from the glass surface (CS<sub>90</sub>) is 25 MPa or more,</p><p>In the destructive test by the indenter indentation test under the condition that a load in the range of 5 kgf to 10 kgf is maintained for 15 seconds with a square pyramid diamond indenter having an indenter angle of 60°, the number of fragments generated within the size of 25 mm × 25 mm less than 20,</p><p>It is a glass plate having the parent composition of the chemically strengthened glass, and from a temperature T 30 to 50 higher than the glass transition point, to (T-300) , for a glass plate of 1 mm in thickness slowly cooled at 0.5 / min, KNO<sub>3</sub>, NaNO<sub>3</sub>, or KNO<sub>3</sub>and NaNO<sub>3</sub>It relates to chemically strengthened glass having a compressive stress layer depth (DOL) of 50 µm or more when an ion exchange treatment is performed for 1 hour with molten salt at 400°C containing a mixed salt of</p><p>In addition, it is a chemically strengthened glass with a thickness t of 2 mm or less,</p><p>Compressive stress value at a depth of 90 μm from the glass surface (CS<sub>90</sub>) is 25 MPa or more,</p><p>In the destructive test by the indenter indentation test under the condition that a load in the range of 5 kgf to 10 kgf is maintained for 15 seconds with a square pyramid diamond indenter having an indenter angle of 60°, the number of fragments generated within the size of 25 mm × 25 mm less than 20,</p><p>It is a glass having the parent composition of the chemically strengthened glass, and from a temperature T 30 to 50 higher than the glass transition point, to (T-300) for a glass plate of 1 mm thickness slowly cooled at 0.5 / min, KNO<sub>3</sub>, NaNO<sub>3</sub>, or KNO<sub>3</sub>and NaNO<sub>3</sub>It also relates to chemically strengthened glass having a compressive stress layer depth (DOL) of 70 µm or more when an ion exchange treatment is performed for 1 hour with a molten salt at 425°C containing a mixed salt of</p><p>In the chemically strengthened glass, it is preferable that any one of the bending strengths σa, σb, and σc after damage is 150 MPa or more. Bending strength σa, σb, σc after scratching, after pressing a diamond indenter (indenter angle of facing angle: 110°) for 15 seconds under a load of 0.5Kgf, 1Kgf, and 2Kgf, respectively, after scratching the glass surface, lower span 30mm, It is a breaking stress value (bending strength, unit: MPa) obtained by performing a 4-point bending test under the conditions of 10 mm of upper span and 0.5 mm/min of crosshead speed. The magnitude of the tensile stress that occurs on the surface of the cover glass when the smartphone is dropped is about 150 MPa, and if any of σa, σb, and σc is 150 MPa or more, even after a scratch by an acute angle object occurs, destruction due to the stress generated by the drop is prevented. can do.</p><p>In the chemically strengthened glass, CS<sub>90</sub>and the compressive stress value at a depth of 100 μm from the glass surface (CS<sub>100</sub>), ΔCS calculated by the following formula<sub>100</sub><sub>-90</sub>It is preferable that (unit: MPa/micrometer) is 0.4 or more.</p><p>ΔCS<sub>100-90</sub>=(CS<sub>90</sub>-CS<sub>100</sub>)/(100-90)</p><p>ΔCS<sub>100-90</sub>(unit: MPa/micrometer), it is also preferable that it is 4.0 or less.</p><p>Moreover, in the said chemically strengthened glass, the compressive stress value CS in the depth of 20 micrometers glass surface side from DOL.<sub>DOL</sub><sub>-20</sub>ΔCS calculated by the following formula using<sub>DOL</sub><sub>-20</sub>It is preferable that (unit: MPa/micrometer) is 0.4 or more.</p><p>ΔCS<sub>DOL</sub><sub>-20</sub>=CS<sub>DOL</sub><sub>-20</sub>/20</p><p>ΔCS<sub>DOL</sub><sub>-20</sub>Silver, 4.0 or less is preferable.</p><p>In the chemically strengthened glass, it is preferable that the surface compressive stress value (CS) is 300 MPa or more.</p><p>In the chemically strengthened glass, it is preferable that the compressive stress layer depth (DOL) is 100 µm or more.</p><p>In the said chemically strengthened glass, it is preferable that thickness t is 0.9 mm or less.</p><p>In the chemically strengthened glass, the area Sc (MPa·µm) of the compressive stress layer is preferably 20000 MPa·µm or more.</p><p>In the chemically strengthened glass, the value Sc/t (MPa) obtained by dividing the area Sc (MPa·µm) of the compressive stress layer by the thickness t (µm) is preferably 28 MPa or more.</p><p>In the chemically strengthened glass, the parent composition of the chemically strengthened glass is SiO<sub>2</sub>50 to 80% of Al<sub>2</sub>O<sub>3</sub>1 to 30%, B<sub>2</sub>O<sub>3</sub>0 to 6%, P<sub>2</sub>O<sub>5</sub>0 to 6%, Li<sub>2</sub>0 to 20% O, Na<sub>2</sub>0 to 20% O, K<sub>2</sub>0 to 10% O, 0 to 20% MgO, 0 to 20% CaO, 0 to 20% SrO, 0 to 15% BaO, 0 to 10% ZnO, TiO<sub>2</sub>0 to 5%, ZrO<sub>2</sub>It is preferable to contain 0 to 8%.</p><p>In the mother composition of the chemically strengthened glass, ZrO by mole percentage expression based on oxide<sub>2</sub>It is preferable that the content of is 1.2% or less.</p><p>In addition, Na by mole percentage expression based on oxide<sub>2</sub>It is preferable that content of O is 3 % or more.</p><p>In addition, K by mole percentage expression on an oxide basis<sub>2</sub>It is preferable that content of O is 0.5 % or more.</p><p>In addition, B by mole percentage expression based on oxide<sub>2</sub>O<sub>3</sub>It is preferable that the content of is 1% or less.</p><p>In addition, Al by mole percentage expression based on oxide<sub>2</sub>O<sub>3</sub>It is preferable that the content of is 11% or less.</p><p>Another embodiment of the present invention relates to chemically strengthened glass satisfying the following formulas (1) and (2).</p><p>NM/Nh1.8 (One)</p><p>KM/Kh3 (2)</p><p>(Here, NM, Nh, KM, and Kh each represent the following.</p><p>NM: The maximum value in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)</p><p>Nh: The central value of the plate thickness in the Na ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)</p><p>KM: The maximum value in the K ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%)</p><p>Kh: The central value of the plate thickness in the K ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%))</p><p>It is preferable that the said chemically strengthened glass further satisfy|fills following formula (3).</p><p>N0/Nh0.8 (3)</p><p>(Here, N0 represents the following.</p><p>N0: The value at the outermost surface in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%))</p><p>It is preferable that the said chemically strengthened glass further satisfy|fills following formula (4).</p><p>N0/NM0.4 (4)</p><p>(Here, N0 represents the following.</p><p>N0: The value at the outermost surface in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%))</p><p>Another embodiment of the present invention relates to chemically strengthened glass satisfying the following formulas (5) and (6).</p><p>NM-Nh2.2 (wt%) (5)</p><p>KM-Kh3 (wt%) (6)</p><p>(Here, NM, Nh, KM, and Kh each represent the following.</p><p>NM: The maximum value in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)</p><p>Nh: The central value of the plate thickness in the Na ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)</p><p>KM: The maximum value in the K ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%)</p><p>Kh: The central value of the plate thickness in the K ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%))</p><p>It is preferable that the said chemically strengthened glass further satisfy|fills following formula (7).</p><p>N0-Nh-0.4 (wt%) (7)</p><p>(Here, N0 represents the following.</p><p>N0: The value at the outermost surface in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%))</p><p>It is preferable that the said chemically strengthened glass further satisfy|fills following formula (8).</p><p>N0-NM-3.5 (wt%) (8)</p><p>(Here, N0 represents the following.</p><p>N0: The value at the outermost surface in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%))</p><p>The chemically strengthened glass has a compressive stress value (CS) at a depth of 20 μm from the glass surface.<sub>20</sub>) is preferably 60 MPa or more.</p><p>The chemically strengthened glass has a compressive stress value (CS) at a depth of 40 μm from the glass surface.<sub>40</sub>) is preferably 60 MPa or more.</p><p>It is preferable that the said chemically strengthened glass has a bending strength of 400 MPa or more.</p><p>The chemically strengthened glass preferably has a surface compressive stress (CS) of 400 MPa or more.</p><p>The chemically strengthened glass preferably has a compressive stress layer depth (DOL) of 100 µm or more.</p><p>It is preferable that the said chemically strengthened glass is plate-shaped whose plate|board thickness t is 2 mm or less.</p><p>The chemically strengthened glass is generated within a size of 25 mm × 25 mm in a destructive test by an indenter indentation test under the condition that a load in the range of 5 kgf to 10 kgf is maintained for 15 seconds with a square pyramid diamond indenter with a facing angle of 60° It is preferable that the number of fragments to be made is 20 or less.</p><p>In the chemically strengthened glass, the parent composition of the chemically strengthened glass is SiO<sub>2</sub>50 to 80% of Al<sub>2</sub>O<sub>3</sub>1 to 30%, B<sub>2</sub>O<sub>3</sub>0 to 5%, P<sub>2</sub>O<sub>5</sub>0 to 4%, Li<sub>2</sub>3 to 20% O, Na<sub>2</sub>0 to 8% O, K<sub>2</sub>0 to 10% O, 3 to 20% MgO, 0 to 20% CaO, 0 to 20% SrO, 0 to 15% BaO, 0 to 10% ZnO, TiO<sub>2</sub>0 to 1%, ZrO<sub>2</sub>It is preferable to contain 0 to 8%.</p><p>In the mother composition of the chemically strengthened glass, ZrO by mole percentage expression based on oxide<sub>2</sub>It is preferable that the content of is 1.2% or less.</p><p>In addition, Na by mole percentage expression based on oxide<sub>2</sub>It is preferable that content of O is 3 % or more.</p><p>In addition, K by mole percentage expression on an oxide basis<sub>2</sub>It is preferable that content of O is 0.5 % or more.</p><p>In addition, B by mole percentage expression based on oxide<sub>2</sub>O<sub>3</sub>It is preferable that the content of is 1% or less.</p><p>In addition, Al by mole percentage expression based on oxide<sub>2</sub>O<sub>3</sub>It is preferable that the content of is 11% or less.</p><p>Further, the present invention is a method for producing the above chemically strengthened glass comprising subjecting the glass to at least two steps of ion exchange treatment, and KNO in molten salt used for the first step ion exchange treatment.<sub>3</sub> NaNO in molten salt having a concentration of 60% by weight or more and used for the second stage ion exchange treatment<sub>3</sub> It also relates to a method for producing chemically strengthened glass, wherein the concentration is 5% by weight or more.</p>
<p>One embodiment of the chemically strengthened glass of the present invention is excellent in sharp-angle scratch strength, high safety at the time of crushing, and short ion exchange time.</p><p>One embodiment of the chemically strengthened glass of the present invention has both high bending strength and high post-damage bending strength.</p>
1 is a schematic diagram showing how a sample for measuring the surface compressive stress (CS) of chemically strengthened glass is prepared, (a) shows a sample before polishing, and (b) shows a flaked sample after polishing. 2 is a concept showing the stress profile of chemically strengthened glass to explain CS (surface compressive stress value), DOL (surface compressive stress layer depth), CT (internal tensile stress), and St (area of internal tensile stress layer) turn Fig. 3 shows a schematic diagram showing a test method for a drop test on sand. 4 is a compressive stress value CS at a depth of 90 µm from the glass surface regarding the chemically strengthened glass of each example;<sub>90</sub>This is a graph plotting the relationship between (unit: MPa) and average crack height (unit: mm). 5 is ΔCS for the chemically strengthened glasses of Examples 4, 6, 8 to 10 and 15;<sub>100</sub><sub>-90</sub>It is a graph plotting the relationship between (unit: MPa/micrometer) and the breaking stress (MPa) in each flaw condition. 6 shows the bending strength and CS after scratching under the condition of a load of 0.5Kgf or 1Kgf;<sub>20</sub>A graph plotting the relationship between 7 shows the bending strength and CS after scratching under the condition of a load of 0.5Kgf or 1Kgf.<sub>40</sub>shows a plot of the relationship between 8 is NM/Nh and CS<sub>20</sub> or CS<sub>40</sub>A graph plotting the relationship between 9 shows N0/Nh and CS<sub>20</sub> or CS<sub>40</sub>A graph plotting the relationship between 10 shows N0/NM and CS<sub>20</sub> or CS<sub>40</sub>A graph plotting the relationship between 11 shows NM-Nh (unit: wt%) and CS<sub>20</sub> or CS<sub>40</sub>A graph plotting the relationship between 12 shows N0-Nh and CS<sub>20</sub> or CS<sub>40</sub>A graph plotting the relationship between 13, N0-NM and CS<sub>20</sub> or CS<sub>40</sub>A graph plotting the relationship between
Hereinafter, the chemically strengthened glass of the present invention will be described in detail.
The chemically strengthened glass of the present invention is chemically strengthened glass I to be described below or chemically strengthened glass II to be described later.
The chemically strengthened glass I of the present invention has a compressive stress value (CS) at a depth of 90 µm from the glass surface.<sub>90</sub>) is 25 MPa or more, and in a destructive test by an indenter indentation test under the condition that a load in the range of 5 kgf to 10 kgf is maintained for 15 seconds with a square pyramid diamond indenter having an indenter angle of 60 °, the size of 25 mm × 25 mm The number of fragments generated inside is 20 or less.
Chemically strengthened glass I of the present invention has a compressive stress layer formed on its surface by chemical strengthening treatment (ion exchange treatment). In a chemical strengthening process, the surface of glass is ion-exchanged, and the surface layer in which a compressive stress remains is formed. Specifically, by ion exchange at a temperature below the glass transition point, alkali metal ions with a small ionic radius (typically Li ions or Na ions) existing in the vicinity of the glass plate surface are converted to alkali ions with a larger ionic radius. (typically Na ions or K ions for Li ions, K ions for Na ions). Thereby, a compressive stress remains on the surface of glass, and the intensity|strength of glass improves.
The chemically strengthened glass I of the present invention preferably has a surface compressive stress value (CS) of 300 MPa or more. When CS of chemically strengthened glass is 300 MPa or more, since it has favorable intensity|strength as a cover glass of a smartphone or a tablet PC, it is preferable. The bending strength of such glass is 350 MPa or more.
When a smartphone or a tablet PC is dropped, a large tensile stress is generated on the back surface of the cover glass due to collision with an obtuse object or a round projection, and the size thereof reaches about 350 MPa. At this time, if CS is 300 MPa or more, since it can withstand the tensile stress of about 350 MPa, it is preferable. CS of the chemically strengthened glass is more preferably 350 MPa or more, still more preferably 400 MPa or more, still more preferably 450 MPa or more.
On the other hand, the upper limit of the CS of the chemically strengthened glass I is not particularly limited, but from the viewpoint of safety at the time of destruction, for example, 2000 MPa or less, preferably 1500 MPa or less, more preferably 1000 MPa or less, still more preferably is 800 MPa or less.
In addition, CS of chemically strengthened glass can be suitably adjusted by adjusting chemical strengthening conditions, a composition of glass, etc.
In addition, CS of the chemically strengthened glass I of this invention is a value CS by the following two types of measurement methods.<sub>F</sub> and CS<sub>A</sub>By , it is defined as follows. Compressive stress value at a depth of x μm from the glass surface (CS<sub>x</sub>) is the same for
CS=CS<sub>F</sub>=1.28×CS<sub>A</sub>
Here, CS<sub>F</sub>is a value measured with a surface stress meter FSM-6000 manufactured by Orihara Seisakusho Co., Ltd., and obtained by a program FsmV attached to the surface stress meter.
Also, CS<sub>A</sub>is a value measured by the following procedure using a birefringent imaging system Abrio-IM manufactured by Tokyo Instruments Corporation. As shown in FIG. 1 , a cross section of chemically strengthened glass having a size of 10 mm × 10 mm or more and a thickness of about 0.2 to 2 mm is polished to a range of 150 to 250 μm to perform thinning. As a polishing procedure, grind to about plus 50 μm of the target thickness with a #1000 diamond electrodeposition grindstone, then grind to about plus 10 μm of the target thickness using a #2000 diamond electrodeposition grindstone, and finally, cerium oxide It is made to the target thickness by performing mirror processing by For the sample thinned to about 200 μm produced as described above, using monochromatic light of λ = 546 nm as a light source, measurement was performed in transmitted light, and the phase difference (retardation) of chemically strengthened glass was measured by a birefringent imaging system. A measurement is performed and a stress is computed by using the obtained value and following formula (9).
F = δ/(C×') ... Equation (9)
In formula (9), F is the stress (MPa), δ is the phase difference (retardation) (nm), C is the photoelastic constant (nm cm)<sup>-1</sup>MPa), d' represents the thickness (cm) of the sample.
The chemically strengthened glass I of the present invention has a compressive stress value (CS) at a depth of 90 µm from the glass surface.<sub>90</sub>) is 25 MPa or more. CS<sub>90</sub>By making it into 25 MPa or more, the sharp-angle object flaw strength can be raised. CS<sub>90</sub>Silver is preferably 30 MPa or more, more preferably 35 MPa or more, still more preferably 40 MPa or more, particularly preferably 45 MPa or more, and most preferably 50 MPa or more.
On the other hand, CS<sub>90</sub>Although the upper limit of is not particularly limited, from the viewpoint of safety at the time of destruction, for example, 250 MPa or less, preferably 200 MPa or less, more preferably 150 MPa or less, particularly preferably 100 MPa or less, most preferably is 75 MPa or less.
In addition, the chemically strengthened glass I of the present invention has a compressive stress value (CS) at a depth of 100 µm from the glass surface from the viewpoint of improving the sharp-angle scratch strength.<sub>100</sub>) is preferably 15 MPa or more. CS<sub>100</sub>Silver is preferably 20 MPa or more, more preferably 23 MPa or more, still more preferably 26 MPa or more, particularly preferably 30 MPa or more, and most preferably 33 MPa or more.
On the other hand, CS<sub>100</sub>The upper limit of is not particularly limited, but from the viewpoint of safety at the time of destruction, for example, 200 MPa or less, preferably 150 MPa or less, more preferably 100 MPa or less, particularly preferably 75 MPa or less, most preferably is 50 MPa or less.
In addition, the CS of chemically tempered glass<sub>90</sub>Ina CS<sub>100</sub>Silver can be suitably adjusted by adjusting chemical strengthening conditions, a composition of glass, etc. similarly to CS.
In addition, in the chemically strengthened glass I of the present invention, CS<sub>90</sub>and CS<sub>100</sub>ΔCS calculated by the following formula using<sub>100</sub><sub>-90</sub>It is preferable that (unit: MPa/micrometer) is 0.4 or more.
ΔCS<sub>100</sub><sub>-90</sub>=(CS<sub>90</sub>-CS<sub>100</sub>)/(100-90)
ΔCS<sub>100</sub><sub>-90</sub>By setting to 0.4 or more, it is possible to increase the bending strength (flexural strength after scratching) after being damaged by an acute angle object. ΔCS<sub>100</sub><sub>-90</sub>More preferably, it is 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.2 or more, 1.4 or more, 1.6 or more, 1.8 or more, and 2.0 or more in the following steps. On the other hand, ΔCS<sub>100</sub><sub>-90</sub>Although the upper limit of is not particularly limited, from the viewpoint of safety of crushing, it is, for example, 4.0 or less, and is preferably 3.0 or less, 2.0 or less, 1.8 or less, 1.6 or less, and 1.4 or less in the following steps.
In addition, in the chemically strengthened glass of the present invention, the compressive stress value CS at the depth of the glass surface side of 20 µm from the DOL<sub>DOL</sub><sub>-20</sub>ΔCS calculated by the following formula using<sub>DOL</sub><sub>-20</sub>It is preferable that (unit: MPa/micrometer) is 0.4 or more.
ΔCS<sub>DOL</sub><sub>-20</sub>=CS<sub>DOL</sub><sub>-20</sub>/20
ΔCS<sub>DOL</sub><sub>-20</sub>By making it into 0.4 or more, it is possible to increase the bending strength (flexural strength after scratching) after being damaged by an acute angle object. ΔCS<sub>DOL</sub><sub>-20</sub>Silver is more preferably 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.2 or more, 1.4 or more, 1.5 or more in the following steps. On the other hand, ΔCS<sub>DOL</sub><sub>-20</sub>Although the upper limit of is not particularly limited, from the viewpoint of safety of crushing, it is, for example, 4.0 or less, preferably 3.0 or less, more preferably 2.0 or less, still more preferably 1.7 or less, and typically 1.6 or less.
Further, in the chemically strengthened glass I of the present invention, it is preferable that the compressive stress layer depth (DOL) is 100 µm or more. When DOL is 100 micrometers or more, the crack resistance by sharp-angle flaws, such as the time of dropping on sand, improves. DOL is preferably 100 µm or more in order to increase the strength of chemically strengthened glass, and more preferably, 110 µm or more, 120 µm or more, 130 µm or more, 140 µm or more, 150 µm or more, 160 more than μm.
On the other hand, the upper limit of DOL is not particularly limited, but from the viewpoint of safety at break, it is, for example, 200 µm or less, preferably 190 µm or less, more preferably 180 µm or less, particularly preferably 150 µm or less. μm or less.
In addition, DOL can be suitably adjusted by adjusting chemical strengthening conditions, the composition of glass, etc.
In this specification, DOL is the depth from the glass surface of the part where stress becomes zero in a stress profile, It is a value measured by the surface stress meter FSM-6000 manufactured by Orihara Seisakusho, and analyzed by the attached program FsmV. In addition, measurement can also be carried out using the birefringent imaging system Abrio-IM by the Tokyo Instruments Corporation, and using the flaky sample as shown in FIG.1(b).
In the chemically strengthened glass I of the present invention, the value of the area Sc (MPa·µm) of the compressive stress layer is preferably 20000 MPa·µm or more. If Sc is 20000 MPa·μm or more, high bending strength can be maintained even in a state in which a scratch is caused by an acute angle object. Sc is preferably 20000 MPa μm or more, and in steps of 22000 MPa μm or more, 24000 MPa μm or more, 26000 MPa μm or more, 28000 MPa μm or more, 30000 MPa μm or more, 32000 MPa μm or more, 34000 MPa μm or more, 36000 MPa · μm or more and more preferably 38000 MPa·μm or more. In addition, although the upper limit of Sc is not specifically limited, From a viewpoint of the safety|security of crushing, it is, for example, 50000 MPa*micrometer or less, Preferably it is 45000 MPa*micrometer or less.
In addition, Sc (MPa·μm) of the chemically strengthened glass I of the present invention is the value Sc by the following two types of measurement methods<sub>F</sub> and Sc<sub>A</sub>By , it is defined as follows.
Sc=Sc<sub>F</sub>=1.515×Sc<sub>A</sub>
Here, Sc<sub>F</sub>is a value calculated using a value measured by a surface stress meter FSM-6000 manufactured by Orihara Seisakusho Co., Ltd. and analyzed by the attached program FsmV, Sc<sub>A</sub>is the above-mentioned CS<sub>A</sub> It is a value obtained by measurement using the birefringent imaging system Abrio-IM and the flaked sample, which is the same method as the measurement.
In addition, the area St (MPa·μm) of the inner tensile layer of the chemically strengthened glass I of the present invention is the value St according to the following two measurement methods.<sub>F</sub> and St<sub>A</sub>By , it is defined as follows.
St=St<sub>F</sub>=1.515×St<sub>A</sub>
Here, St<sub>F</sub>is a value calculated using a value measured by a surface stress meter FSM-6000 manufactured by Orihara Seisakusho Corporation and analyzed by the attached program FsmV,<sub>A</sub>is the above-mentioned CS<sub>A</sub> It is a value obtained by measurement using the birefringent imaging system Abrio-IM and the flaked sample, which is the same method as the measurement. In the same manner as above, a stress profile is created by the dilution method, and St<sub>F</sub> or St<sub>A</sub>By calculating , St can be obtained.
2 shows a conceptual diagram of Sc and St. Sc and St are theoretically equivalent values, and it is preferable to calculate it so that 0.95<Sc/St<1.05.
Further, in the chemically strengthened glass I of the present invention, the value Sc/t (MPa) obtained by dividing the area Sc (MPa·µm) of the compressive stress layer by the plate thickness t (µm) is preferably 28 MPa or more. When Sc/t is 28 MPa or more, crack resistance by sharp-angle scratches, such as when it is dropped on sand, improves. Sc/t is more preferably 30 MPa or more, still more preferably, 32 MPa or more, 34 MPa or more, 36 MPa or more, 38 MPa or more, 40 MPa or more, 42 MPa or more, 44 MPa or more, 46 MPa or more, 48 MPa or more, 50 MPa or more. More than that. On the other hand, the upper limit of Sc/t is not particularly limited, but is, for example, 60 MPa or less, preferably 55 MPa or less, from the viewpoint of safety of crushing.
In addition, the chemically strengthened glass I of the present invention is a destructive test by an indenter indentation test under the condition that a load in the range of 5kgf to 10kgf is maintained for 15 seconds with a square pyramid diamond indenter having an indenter angle of 60° facing angle, The number of fragments generated within the size of 25 mm × 25 mm is 20 or less. If the number of fragments (number of fractures) in the destructive test by the indenter indentation test is 20 or less, even if they are destroyed, high safety can be ensured. The said number of crushing becomes like this. Preferably it is 10 or less, More preferably, it is 5 or less.
Further, it is preferable that the chemically strengthened glass I of the present invention has a bending strength of 150 MPa or more after damage. The magnitude of the tensile stress generated on the surface of the cover glass at the time of falling of the smartphone is about 150 MPa, and if the bending strength is 150 MPa or more, it is possible to prevent fracture due to the stress generated by the drop even after a scratch by an acute angle object occurs. The bending strength after damage becomes like this. Preferably it is 200 MPa or more, More preferably, it is 250 MPa or more. As a method of making a flaw, an indenter press-in test etc. which press a diamond indenter (indenter angle of facing angle: 110 degree) can be used.
Chemically strengthened glass I of the present invention is a diamond indenter (indenter angle of facing angle: 110°) by pressing for 15 seconds under a load of 0.5Kgf, after scratching the glass surface, lower span 30mm, upper span 10mm, crosshead speed It is preferable that the breaking stress value σa (bending strength, unit: MPa) obtained by performing a four-point bending test under the conditions of 0.5 mm/min is 150 MPa or more. σa is preferably 200 MPa or more, more preferably 250 MPa or more, still more preferably 300 MPa or more.
Chemically strengthened glass I of the present invention is a diamond indenter (indentation angle of facing angle: 110°) by pressing for 15 seconds under a load of 1Kgf, after scratching the glass surface, lower span 30mm, upper span 10mm, crosshead speed 0.5 It is preferable that the breaking stress value σb (bending strength, unit: MPa) obtained by performing a four-point bending test under the conditions of mm/min is 150 MPa or more. σb is preferably 200 MPa or more, more preferably 250 MPa or more, still more preferably 300 MPa or more.
Chemically strengthened glass I of the present invention is a diamond indenter (indenter angle of facing angle: 110°) by pressing for 15 seconds under a load of 2Kgf, after scratching the glass surface, lower span 30mm, upper span 10mm, crosshead speed 0.5 It is preferable that the breaking stress value σc (bending strength, unit: MPa) obtained by performing a four-point bending test under the conditions of mm/min is 150 MPa or more. σc is preferably 200 MPa or more, more preferably 250 MPa or more, still more preferably 300 MPa or more.
Next, the chemically strengthened glass II of this invention is demonstrated in detail.
Chemically strengthened glass II of one embodiment is chemically strengthened glass which satisfy|fills following formula (1) and (2).
NM/Nh1.8 (One)
KM/Kh3 (2)
Here, NM, Nh, KM, and Kh respectively indicate the following.
NM: The maximum value in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)
Nh: The central value of the plate thickness in the Na ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)
KM: The maximum value in the K ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%)
Kh: The central value of the plate thickness in the K ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%)
In addition, EPMA means Electron Probe Micro Analyzer (electron beam micro analyzer).
In addition, the central value of the plate thickness in the Na ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>The value (Nh) converted to O (wt%) is the Na ion concentration at the center of the plate thickness of Na<sub>2</sub>It is a value converted to O (wt%), for example, in the case of chemically strengthened glass having a plate thickness of 0.8 mm, the Na ion concentration at a position of 0.4 mm from the surface is Na<sub>2</sub>It is a value converted into O (weight%). It is assumed that it is defined similarly also about Kh.
(NM/Nh1.8 (One))
As also shown in Examples to be described later, according to the knowledge of the present inventors, there is a strong correlation between the compressive stress value at a depth of 20 to 40 µm from the glass surface and the bending strength after scratches, and 20 to 40 from the glass surface The higher the compressive stress value at a depth of mu m , the higher the post-damage bending strength tends to be obtained.
Moreover, as NM/Nh becomes large, there exists a tendency for the compressive stress value at the depth part of 20-40 micrometers from the glass surface to become high. In the present invention, in order to achieve sufficient post-damage flexural strength in order to improve the failure rate of the cover glass, NM/Nh is required to be 1.8 or more. , 3 or more, 3.2 or more, and 3.4 or more are preferable. On the other hand, the upper limit of NM/Nh is not particularly limited, but from the viewpoint of safety at the time of crushing, for example, it is preferably 5 or less, more preferably 4.5 or less, still more preferably 4 or less.
(N0/Nh0.8 (3))
In addition, in the chemically strengthened glass of the present embodiment, the value at the outermost surface in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>It is preferable that N0/Nh which is a ratio of N0 which is a value converted into O (weight%), and said Nh is 0.8 or more.
According to the knowledge of the present inventors, there exists a tendency for the compressive stress value at the depth part of 20-40 micrometers from a glass surface to become high, so that N0/Nh becomes large. In the present embodiment, in order to obtain sufficient post-damage flexural strength to improve the failure rate of the cover glass, it is preferable that N0/Nh is 0.8 or more, and in the following steps, 1 or more, 1.2 or more, 1.4 or more, 1.6 or more, 1.8 or more. More preferably 2 or more, 2 or more, 2.2 or more, 2.4 or more, 2.6 or more, 2.8 or more, and 3 or more. On the other hand, the upper limit of N0/Nh is not particularly limited, but from the viewpoint of safety of crushing, for example, it is preferably 5 or less, more preferably 4.5 or less, and still more preferably 4 or less.
(N0/NM0.4 (4))
Moreover, in the chemically strengthened glass of this embodiment, it is preferable that N0/NM which is ratio of above-mentioned N0 and above-mentioned NM is 0.4 or more.
According to the knowledge of the present inventors, as N0/NM becomes large, there exists a tendency for the compressive stress value at the depth part of 20-40 micrometers from the glass surface to become high. In this embodiment, in order to set it as sufficient post-damage bending strength in order to improve the failure rate of a cover glass, it is preferable that N0/NM is 0.4 or more, and below, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 Above, it is more preferable that it is 0.95 or more.
(KM/Kh3 (2))
In the chemically strengthened glass II of the present embodiment, a large compressive stress is introduced into the glass surface layer by Na-K exchange in which Na ions in the glass are exchanged with K ions to increase the bending strength. Here, from the viewpoint of improving the strength reliability of the cover glass, the bending strength is preferably 400 MPa or more. More than, 5.5 or more, 6 or more, 6.5 or more, and 7 or more are more preferable.
Further, chemically strengthened glass II according to another embodiment is chemically strengthened glass that satisfies the following formulas (5) and (6).
NM-Nh2.2 (wt%) (5)
KM-Kh3 (wt%) (6)
(NM-Nh2.2 (wt%) (5))
As NM-Nh becomes large, the compressive stress value at a depth of 20 to 40 µm from the glass surface tends to increase. In this embodiment, in order to set it as sufficient post-damage bending strength in order to improve the failure rate of a cover glass, it is required that NM-Nh is 2.2 wt% or more, and, in the following steps, 2.4 wt% or more, 2.6 wt% or more, 2.8 wt% or more, 3 wt% or more, 3.2 wt% or more, 3.4 wt% or more, 3.6 wt% or more, 3.8 wt% or more, 4 wt% or more, 4.2 wt% or more, 4.4 wt% or more, 4.6 wt% or more, 4.8 wt% Above, it is preferable that it is 5 wt% or more. On the other hand, the upper limit of NM-Nh is not particularly limited, but from the viewpoint of safety at the time of crushing, for example, it is preferably 7 wt% or less, more preferably 6.5 wt% or less, and still more preferably 6 wt% or less.
(N0-Nh-0.4 (wt%) (7))
In addition, in the chemically strengthened glass II of this embodiment, the value at the outermost surface in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>It is preferable that N0 which is a value converted into O (wt%) and N0-Nh which is a difference between the Nh is -0.4 wt% or more.
According to the knowledge of the present inventors, there exists a tendency for the compressive stress value of a 20-40 micrometers depth part from a glass surface to become high, so that N0-Nh becomes large. In this embodiment, in order to set it as sufficient post-damage bending strength in order to improve the failure rate of a cover glass, it is preferable that N0-Nh is -0.4 wt% or more, and below stepwise, 0 wt% or more, 0.5 wt% or more, 1 wt% % or more, 1.5 wt% or more, 2 wt% or more, 2.5 wt% or more, 3 wt% or more, 3.5 wt% or more, 4 wt% or more, 4.5 wt% or more, 5 wt% or more are more preferable. On the other hand, the upper limit of N0-Nh is not particularly limited, but from the viewpoint of safety of crushing, for example, it is preferably 7 wt% or less, more preferably 6.5 wt% or less, and still more preferably 6 wt% or less.
(N0-NM-3.5 (wt%) (8))
Moreover, in the chemically strengthened glass II of this embodiment, it is preferable that N0-NM which is the difference between above-mentioned N0 and above-mentioned NM is -3.5 wt% or more.
According to the knowledge of the present inventors, as N0-NM becomes large, there exists a tendency for the compressive stress value at the depth part of 20-40 micrometers from a glass surface to become high. In this embodiment, in order to set it as sufficient post-damage bending strength in order to improve the failure rate of a cover glass, it is preferable that N0-NM is -3.5 wt% or more, and, in the following steps, -3 wt% or more, -2.5 wt% or more , -2 wt% or more, -1.5 wt% or more, -1 wt% or more, -0.5 wt% or more, -0.25 wt% or more, -0.1 wt% or more are more preferable.
(KM-Kh3 (wt%) (6))
In the chemically strengthened glass II of the present embodiment, a large compressive stress is introduced into the glass surface layer by Na-K exchange in which Na ions in the glass are exchanged with K ions to increase the bending strength. Here, from the viewpoint of improving the strength reliability of the cover glass, the bending strength is preferably 400 MPa or more. 4.5wt% or more, 5wt% or more, 5.5wt% or more, 6wt% or more, 6.5wt% or more, 7wt% or more, 7.5wt% or more, 8wt% or more, 8.5t% or more, 9wt% or more, 9.5wt% or more, It is preferable that it is 10 wt% or more.
The chemically strengthened glass II of the present invention preferably has a surface compressive stress (CS) of 400 MPa or more. Here, in order to improve the strength reliability of a cover glass, it is preferable that the bending strength of glass is 400 Mpa or more. When the CS of the chemically strengthened glass is 400 MPa or more, the bending strength of the glass is 400 MPa or more. CS of the chemically strengthened glass is more preferably 500 MPa or more, still more preferably 600 MPa or more.
On the other hand, the upper limit of the CS of the chemically strengthened glass II is not particularly limited, but from the viewpoint of safety at the time of destruction, for example, 2000 MPa or less, preferably 1500 MPa or less, more preferably 1000 MPa or less, still more preferably is 800 MPa or less.
In addition, CS of chemically strengthened glass can be suitably adjusted by adjusting chemical strengthening conditions, a composition of glass, etc.
In addition, CS of the chemically strengthened glass II of this invention is a value CS by the following two types of measurement methods.<sub>F</sub> and CS<sub>A</sub>By , it is defined as follows. Compressive stress value at a depth of x μm from the glass surface (CS<sub>x</sub>) is the same for
CS=CS<sub>F</sub>1.28×CS<sub>A</sub>
Here, CS<sub>F</sub>is a value measured by a surface stress meter FSM-6000 manufactured by Orihara Seisakusho Co., Ltd., and obtained by the attached program FsmV of the surface stress meter.
Also, CS<sub>A</sub>is a value measured by the procedure described above using the birefringent imaging system Abrio-IM manufactured by Tokyo Instruments Corporation.
The chemically strengthened glass II of the present invention preferably has a bending strength of 200 MPa or more after damage. When a smartphone or a tablet PC is dropped, a tensile stress is generated on the surface of the cover glass, and the size thereof reaches about 200 MPa. Since scratches are generated on the surface of the cover glass due to collision or the like with an acute-angled object, the failure rate of the cover glass can be improved even in a state where the bending strength is 200 MPa or more in a damaged state.
Here, the flexural strength after scratching is a diamond indenter (indenter angle of facing angle: 110°) is pressed for 15 seconds under a load of 0.5 or 1 kgf, after scratching the glass surface, lower span 30 mm, upper span 10 mm, cross The fracture stress value (bending strength, unit: MPa) obtained by performing a four-point bending test under the conditions of a head speed of 0.5 mm/min is shown.
The chemically strengthened glass II of the present invention has a compressive stress value (CS) at a depth of 20 µm from the glass surface.<sub>20</sub>) is preferably 60 MPa or more. CS<sub>20</sub>If it is this 60 MPa or more, the bending test strength after a flaw can be made into 200 MPa or more, and the failure rate of a cover glass improves. CS<sub>20</sub>Silver is more preferably 80 MPa or more, still more preferably, 100 MPa or more, 120 MPa or more, 140 MPa or more, 160 MPa or more, 180 MPa or more, 200 MPa or more, 220 MPa or more, 240 MPa or more, 260 MPa or more, 280 MPa or more, 300 MPa or more. More than that.
On the other hand, CS<sub>20</sub>Although the upper limit of is not particularly limited, from the viewpoint of safety of crushing, it is, for example, 500 MPa or less, preferably 400 MPa or less, more preferably 350 MPa or less, and particularly preferably 320 MPa or less.
The chemically strengthened glass II of the present invention has a compressive stress value (CS) at a depth of 40 µm from the glass surface.<sub>40</sub>) is preferably 60 MPa or more. CS<sub>40</sub>If it is this 60 MPa or more, the bending test strength after a flaw can be made into 200 MPa or more, and the failure rate of a cover glass improves. CS<sub>40</sub>More preferably, in the following steps, 70 MPa or more, 80 MPa or more, 90 MPa or more, 100 MPa or more, 110 MPa or more, 120 MPa or more, 130 MPa or more, 150 MPa or more, 160 MPa or more, 170 MPa or more, 180 MPa or more.
On the other hand, CS<sub>40</sub>Although the upper limit of is not specifically limited, From a viewpoint of the safety|security of crushing, it is, for example, 300 MPa or less, Preferably it is 250 MPa or less, More preferably, it is 200 MPa or less.
In addition, the CS of chemically tempered glass<sub>20</sub>Ina CS<sub>40</sub>Silver can be suitably adjusted by adjusting chemical strengthening conditions, a composition of glass, etc. similarly to CS.
Moreover, in the chemically strengthened glass II of this invention, it is preferable that the compressive-stress layer depth (DOL) is 100 micrometers or more. When the DOL is 100 µm or more, it becomes possible to significantly improve the strength against destruction due to scratches caused by sharp objects, such as when it is dropped on sand. DOL becomes like this. More preferably, it is 110 micrometers or more, More preferably, it is 130 micrometers or more, Especially preferably, it is 150 micrometers or more.
On the other hand, the upper limit of the DOL is not particularly limited, but from the viewpoint of safety at the time of destruction, it is, for example, 200 µm or less, preferably 180 µm or less, and more preferably 160 µm or less.
In addition, DOL can be suitably adjusted by adjusting chemical strengthening conditions, the composition of glass, etc.
In addition, the DOL of the chemically strengthened glass II of this invention is the depth from the glass surface of the part where the stress becomes zero in the stress profile, measured by the surface stress meter FSM-6000 manufactured by Orihara Seisakusho, and by the attached program FsmV. value to be interpreted. In addition, measurement can also be carried out using the birefringent imaging system Abrio-IM by the Tokyo Instruments Corporation, and using the flaky sample as shown in FIG.1(b).
In addition, the chemically strengthened glass II of the present invention is a destructive test by an indenter indentation test under the condition that a load in the range of 5kgf to 10kgf is maintained for 15 seconds with a square pyramid diamond indenter having an indenter angle of a facing angle of 60°, The number of fragments generated within the size of 25 mm × 25 mm is 20 or less. If the number of fragments (number of fractures) in the destructive test by the indenter indentation test is 20 or less, even if they are destroyed, high safety can be ensured. The number of crushed pieces is preferably 30 or less, and more preferably 40 or less.
Then, the mother composition of the chemically strengthened glass in this invention is demonstrated.
In the present specification, the mother composition of chemically strengthened glass refers to the composition of the glass before chemical strengthening (hereinafter, may be referred to as mother glass and may also be referred to as glass for chemical strengthening). Here, a portion having a tensile stress of the chemically strengthened glass (hereinafter also referred to as a tensile stress portion) can be considered as a portion not ion-exchanged. Therefore, the tensile stress portion of the chemically strengthened glass has the same composition as that of the mother glass, and the composition of the tensile stress portion can be regarded as the mother composition.
Below, suitable content of each component which can be contained in the mother composition of chemically strengthened glass is demonstrated. In addition, unless otherwise indicated, content of each component shall be expressed by the molar percentage expression of an oxide basis.
Although the composition of glass can also be simply calculated|required by the semi-quantitative analysis by a fluorescent X-ray method, it can measure with wet analysis methods, such as ICP emission analysis, more precisely.
As the composition for the chemically strengthened glass of the present invention (the mother composition of the chemically strengthened glass of the present invention), for example, SiO<sub>2</sub>50 to 80% of Al<sub>2</sub>O<sub>3</sub>1 to 30%, B<sub>2</sub>O<sub>3</sub>0 to 5%, P<sub>2</sub>O<sub>5</sub>0 to 4%, Li<sub>2</sub>3 to 20% O, Na<sub>2</sub>0 to 8% O, K<sub>2</sub>0 to 10% O, 3 to 20% MgO, 0 to 20% CaO, 0 to 20% SrO, 0 to 15% BaO, 0 to 10% ZnO, TiO<sub>2</sub>0 to 1%, ZrO<sub>2</sub>and those containing 0 to 8%.
For example, SiO<sub>2</sub>63 to 80%, Al<sub>2</sub>O<sub>3</sub>7 to 30%, B<sub>2</sub>O<sub>3</sub>0 to 5%, P<sub>2</sub>O<sub>5</sub>0 to 4%, Li<sub>2</sub>5 to 15% O, Na<sub>2</sub>4 to 8% O, K<sub>2</sub>0 to 2% O, 3 to 10% MgO, 0 to 5% CaO, 0 to 20% SrO, 0 to 15% BaO, 0 to 10% ZnO, TiO<sub>2</sub>0 to 1%, ZrO<sub>2</sub>contains 0 to 8% of Ta<sub>2</sub>O<sub>5</sub>, Gd<sub>2</sub>O<sub>3</sub>, As<sub>2</sub>O<sub>3</sub>, Sb<sub>2</sub>O<sub>3</sub>glass that does not contain
SiO<sub>2</sub>is a component constituting the skeleton of glass. Moreover, it is a component which improves chemical durability, is a component which reduces the crack generation when a flaw (indentation) occurs on the glass surface, and SiO<sub>2</sub>The content of is preferably 50% or more. SiO<sub>2</sub>The content of is more preferably 54% or more, 58% or more, 60% or more, 63% or more, 66% or more, 68% or more in the following steps. On the other hand, SiO<sub>2</sub>When the content of is more than 80%, the meltability is remarkably reduced. SiO<sub>2</sub>The content of is 80% or less, more preferably 78% or less, still more preferably 76% or less, particularly preferably 74% or less, and most preferably 72% or less.
Al<sub>2</sub>O<sub>3</sub>Silver is a component that improves the friability of chemically strengthened glass. Here, the high friability of the glass means that the number of fragments when the glass is cracked is small. Since fragments do not easily scatter when broken, glass with high friability can be said to have high safety. Also, Al<sub>2</sub>O<sub>3</sub>Since silver is an effective component for improving the ion exchange performance during chemical strengthening and increasing the surface compressive stress after strengthening, Al<sub>2</sub>O<sub>3</sub>The content of is preferably 1% or more. Al<sub>2</sub>O<sub>3</sub>The content of is more preferably 3% or more, 5% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, 12% or more, 13% or more in the following steps. On the other hand, Al<sub>2</sub>O<sub>3</sub>When content of is more than 30 %, the acid resistance of glass will fall or loss-of-clarity temperature will become high. In addition, the viscosity of the glass increases and the meltability decreases. Al<sub>2</sub>O<sub>3</sub>The content of is preferably 30% or less, more preferably 25% or less, still more preferably 20% or less, particularly preferably 18% or less, and most preferably 15% or less. On the other hand, Al<sub>2</sub>O<sub>3</sub>When content of is large, the temperature at the time of glass melting becomes high, and productivity falls. When considering the productivity of glass, Al<sub>2</sub>O<sub>3</sub>The content of is preferably 11% or less, and is preferably 10% or less, 9% or less, 8% or less, and 7% or less in the following steps.
B<sub>2</sub>O<sub>3</sub>Silver is a component that improves the chipping resistance of the chemically strengthened glass or chemically strengthened glass, and also improves the meltability of the glass. B<sub>2</sub>O<sub>3</sub>is not required, but B<sub>2</sub>O<sub>3</sub>In order to improve meltability, content in the case of containing it becomes like this. Preferably it is 0.5 % or more, More preferably, it is 1 % or more, More preferably, it is 2 % or more. On the other hand, B<sub>2</sub>O<sub>3</sub>When the content of is more than 5%, streaks are generated at the time of melting, and the quality of the glass for chemical strengthening tends to deteriorate. B<sub>2</sub>O<sub>3</sub>The content of is more preferably 4% or less, still more preferably 3% or less, and particularly preferably 1% or less. In order to improve acid resistance, it is preferable not to contain.
P<sub>2</sub>O<sub>5</sub>is a component that improves ion exchange performance and chipping resistance. P<sub>2</sub>O<sub>5</sub>It is not necessary to contain P<sub>2</sub>O<sub>5</sub>In the case of containing , the content is preferably 0.5% or more, more preferably 1% or more, and still more preferably 2% or more. On the other hand, P<sub>2</sub>O<sub>5</sub>When the content of is more than 4%, the crushability of the glass is remarkably lowered, and the acid resistance is remarkably lowered. P<sub>2</sub>O<sub>5</sub>The content of is preferably 4% or less, more preferably 3% or less, still more preferably 2% or less, particularly preferably 1% or less. In order to improve acid resistance, it is preferable not to contain.
Li<sub>2</sub>O is a component that forms a surface compressive stress by ion exchange, and is a component that improves the crushability of chemically strengthened glass.
Li ions on the glass surface are exchanged for Na ions, and the CS<sub>40</sub>When chemical strengthening treatment is performed so that this 60 MPa or more, Li<sub>2</sub>The content of O is preferably 3% or more, more preferably 4% or more, still more preferably 5% or more, particularly preferably 6% or more, and typically 7% or more. On the other hand, Li<sub>2</sub>When content of O exceeds 20 %, the acid resistance of glass will fall remarkably. Li<sub>2</sub>The content of O is preferably 20% or less, more preferably 18% or less, still more preferably 16% or less, particularly preferably 15% or less, and most preferably 13% or less.
On the other hand, by exchanging Na ions on the glass surface with K ions, the CS<sub>40</sub>In the case of performing the chemical strengthening treatment to be 60 MPa or more, Li<sub>2</sub>When the content of O exceeds 3%, the magnitude of the compressive stress decreases, and CS<sub>40</sub>It becomes difficult to achieve this 60 MPa or more. In this case, Li<sub>2</sub>The content of O is preferably 3% or less, more preferably 2% or less, still more preferably 1% or less, particularly preferably 0.5% or less, and most preferably Li<sub>2</sub>It is substantially free of O.
In addition, in this specification, "substantially free" means that it does not contain except unavoidable impurities contained in raw materials etc., ie, does not contain intentionally. Specifically, it points out that content in a glass composition is less than 0.1 mol%.
Na<sub>2</sub>O is a component that forms a surface compressive stress layer by ion exchange and improves the meltability of glass.
Li ions on the glass surface are exchanged for Na ions, and the CS<sub>40</sub>When chemical strengthening treatment is performed so that this 60 MPa or more, Na<sub>2</sub>Although it is not necessary to contain O, when attaching importance to the meltability of glass, you may contain it. Na<sub>2</sub>The content in the case of containing O is preferably 1% or more. Na<sub>2</sub>Content of O becomes like this. More preferably, it is 2 % or more, More preferably, it is 3 % or more. On the other hand, Na<sub>2</sub>When the content of O exceeds 8%, the surface compressive stress formed by ion exchange is remarkably reduced. Na<sub>2</sub>The content of O is preferably 8% or less, more preferably 7% or less, still more preferably 6% or less, particularly preferably 5% or less, and most preferably 4% or less.
On the other hand, by exchanging Na ions on the glass surface with K ions, the CS<sub>40</sub>When performing a chemical strengthening process so that it may become this 60 MPa or more, Na is essential, and the content is 5 % or more. Na<sub>2</sub>Content of O becomes like this. Preferably it is 5 % or more, More preferably, it is 7 % or more, More preferably, it is 9 % or more, Especially preferably, it is 11 % or more, Especially preferably, it is 12 % or more. On the other hand, Na<sub>2</sub>When content of O exceeds 20 %, the acid resistance of glass will fall remarkably. Na<sub>2</sub>The content of O is preferably 20% or less, more preferably 18% or less, still more preferably 16% or less, particularly preferably 15% or less, and most preferably 14% or less.
When Li ions and Na ions, Na ions and K ions on the glass surface are simultaneously ion-exchanged by a method such as immersion in a mixed molten salt of potassium nitrate and sodium nitrate, Na<sub>2</sub>The content of O is preferably 10% or less, more preferably 9% or less, still more preferably 7% or less, particularly preferably 6% or less, and most preferably 5% or less. Also, Na<sub>2</sub>Content of O becomes like this. Preferably it is 2 % or more, More preferably, it is 3 % or more, More preferably, it is 4 % or more.
K<sub>2</sub>O may be contained in order to improve the ion exchange performance. K<sub>2</sub>Content in the case of containing O becomes like this. Preferably it is 0.5 % or more, More preferably, it is 1 % or more, More preferably, it is 2 % or more, Especially preferably, it is 3 % or more. On the other hand, K<sub>2</sub>When the content of O exceeds 10%, the friability of chemically strengthened glass decreases, so that K<sub>2</sub>The content of O is preferably 10% or less. K<sub>2</sub>The content of O is more preferably 8% or less, still more preferably 6% or less, particularly preferably 4% or less, and most preferably 2% or less.
MgO is a component that increases the surface compressive stress of chemically strengthened glass, and is a component that improves friability, and is preferably contained. Content in the case of containing MgO becomes like this. Preferably it is 3 % or more, More preferably, it is 4 % or more, 5 % or more, 6 % or more, 7 % or more, and 8 % or more in the following steps. On the other hand, when the content of MgO exceeds 20%, the glass for chemical strengthening tends to devitrify at the time of melting. The MgO content is preferably 20% or less, more preferably 18% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, and 10% or less in the following steps.
CaO is a component that improves the meltability of the chemically strengthened glass, and is a component that improves the crushability of the chemically strengthened glass, and may be contained. Content in the case of containing CaO becomes like this. Preferably it is 0.5 % or more, More preferably, it is 1 % or more, More preferably, it is 2 % or more, Especially preferably, it is 3 % or more, Especially preferably, it is 5 % or more. . On the other hand, when the content of CaO exceeds 20%, the ion exchange performance is remarkably deteriorated, so 20% or less is preferable. Content of CaO becomes like this. More preferably, it is 14 % or less, More preferably, 10 % or less, 8 % or less, 6 % or less, 3 % or less, and 1 % or less are preferable.
SrO is a component that improves the meltability of the chemically strengthened glass, and is a component that improves the crushability of the chemically strengthened glass, and may be contained. The content in the case of containing SrO is preferably 0.5% or more, more preferably 1% or more, still more preferably 2% or more, particularly preferably 3% or more, particularly preferably 5% or more. . On the other hand, when the content of SrO exceeds 20%, the ion exchange performance is remarkably deteriorated, so 20% or less is preferable. Content of SrO becomes like this. More preferably, it is 14 % or less, More preferably, 10 % or less, 8 % or less, 6 % or less, 3 % or less, and 1 % or less are preferable.
BaO is a component that improves the meltability of the chemically strengthened glass, and is a component that improves the friability of the chemically strengthened glass, and may be contained. Content in the case of containing BaO becomes like this. Preferably it is 0.5 % or more, More preferably, it is 1 % or more, More preferably, it is 2 % or more, Especially preferably, it is 3 % or more, Especially preferably, it is 5 % or more. . On the other hand, when content of BaO exceeds 15 %, ion exchange performance will fall remarkably. It is preferable that content of BaO is 15 % or less, More preferably, it is 10 % or less, 8 % or less, 6 % or less, 3 % or less, and 1 % or less in the following steps.
ZnO is a component which improves the meltability of glass, and you may contain it. Content in the case of containing ZnO becomes like this. Preferably it is 0.25 % or more, More preferably, it is 0.5 % or more. On the other hand, when the content of ZnO exceeds 10%, the weather resistance of the glass is remarkably deteriorated. The content of ZnO is preferably 10% or less, more preferably 7% or less, still more preferably 5% or less, particularly preferably 2% or less, and most preferably 1% or less.
TiO<sub>2</sub>is a component that improves the crushability of chemically strengthened glass, and may be contained. TiO<sub>2</sub>In the case of containing , the content is preferably 0.1% or more, more preferably 0.15% or more, and still more preferably 0.2% or more. On the other hand, TiO<sub>2</sub>When the content of is more than 5%, devitrification tends to occur at the time of melting, and there is a possibility that the quality of the chemically strengthened glass is deteriorated. TiO<sub>2</sub>It is preferable that content of is 1 % or less, More preferably, it is 0.5 % or less, More preferably, it is 0.25 % or less.
ZrO<sub>2</sub>is a component that increases the surface compressive stress by ion exchange, has an effect of improving the crushability of the glass for chemical strengthening, and may be contained. ZrO<sub>2</sub>Content in the case of containing it becomes like this. Preferably it is 0.5 % or more, More preferably, it is 1 % or more. On the other hand, ZrO<sub>2</sub>When the content of is more than 8%, devitrification tends to occur at the time of melting, and there is a possibility that the quality of the chemically strengthened glass is deteriorated. ZrO<sub>2</sub>The content of is preferably 8% or less, more preferably 6% or less, still more preferably 4% or less, particularly preferably 2% or less, and most preferably 1.2% or less.
Y<sub>2</sub>O<sub>3</sub>, La<sub>2</sub>O<sub>3</sub>, Nb<sub>2</sub>O<sub>5</sub>is a component that improves the crushability of chemically strengthened glass, and may be contained. Each content in the case of containing these components is preferably 0.5% or more, more preferably 1% or more, still more preferably 1.5% or more, particularly preferably 2% or more, particularly preferably 2.5% or more. % or more. On the other hand, Y<sub>2</sub>O<sub>3</sub>, La<sub>2</sub>O<sub>3</sub>, Nb<sub>2</sub>O<sub>5</sub>When the content of each exceeds 8%, the glass tends to devitrify at the time of melting, and there is a risk that the quality of the chemically strengthened glass may deteriorate. Y<sub>2</sub>O<sub>3</sub>, La<sub>2</sub>O<sub>3</sub>, Nb<sub>2</sub>O<sub>5</sub>The content of each is preferably 8% or less, more preferably 6% or less, still more preferably 5% or less, particularly preferably 4% or less, and most preferably 3% or less.
Ta<sub>2</sub>O<sub>5</sub>, Gd<sub>2</sub>O<sub>3</sub>Silver may be contained in a small amount in order to improve the crushability of chemically strengthened glass, but since the refractive index and reflectance become high, 1% or less is preferable, 0.5% or less is more preferable, and it is still more preferable not to contain it.
In addition, when coloring glass and using it, you may add a coloring component in the range which does not impair achievement of a desired chemical strengthening characteristic. As a coloring component, Co<sub>3</sub>O<sub>4</sub>, MnO<sub>2</sub>, Fe<sub>2</sub>O<sub>3</sub>, NiO, CuO, Cr<sub>2</sub>O<sub>3</sub>, V<sub>2</sub>O<sub>5</sub>, Bi<sub>2</sub>O<sub>3</sub>, SeO<sub>2</sub>, TiO<sub>2</sub>, CeO<sub>2</sub>, Er<sub>2</sub>O<sub>3</sub>, Nd<sub>2</sub>O<sub>3</sub> etc. are mentioned as suitable.
Content of a coloring component is a molar percentage expression on an oxide basis, and the range of 7 % or less in total is preferable. When it exceeds 7 %, it becomes easy to devitrify glass and is unpreferable.
This content is preferably 5% or less, more preferably 3% or less, and still more preferably 1% or less. When giving priority to the visible light transmittance|permeability of glass, it is preferable not to contain these components substantially.
As a fining agent at the time of melting of glass, SO<sub>3</sub>, a chloride, a fluoride, etc. may be contained suitably. As<sub>2</sub>O<sub>3</sub>It is preferable not to contain silver. Sb<sub>2</sub>O<sub>3</sub>When it contains, 0.3 % or less is preferable, 0.1 % or less is more preferable, and it is most preferable not to contain it.
Furthermore, it is preferable that the chemically strengthened glass of this invention has on the surface at least 1 sort(s) selected from the group which consists of a sodium ion, a silver ion, a potassium ion, a cesium ion, and a rubidium ion. Thereby, compressive stress is induced in the surface, and glass is strengthened. Moreover, by having silver ion on the surface, antibacterial property can be provided.
In addition, in the present invention, with respect to a glass plate having a mother composition of chemically strengthened glass and annealed under the following conditions, with a thickness of 1 mm, KNO<sub>3</sub>, NaNO<sub>3</sub>, or KNO<sub>3</sub>and NaNO<sub>3</sub>It is preferable to select the parent composition of the chemically strengthened glass so that the DOL is 50 µm or more when an ion exchange treatment is performed for 1 hour using a molten salt at 400°C containing a mixed salt of Here, the slow cooling shall be performed at a cooling rate of 0.5°C/min from a temperature T°C higher than the glass transition point by 30°C to 50°C to (T-300)°C.
In addition, in the present invention, with respect to a glass plate having a mother composition of chemically strengthened glass and annealed under the following conditions, with a thickness of 1 mm, KNO<sub>3</sub>, NaNO<sub>3</sub>, or KNO<sub>3</sub>and NaNO<sub>3</sub>It is preferable to select a mother composition of chemically strengthened glass whose DOL is 70 µm or more when an ion exchange treatment is performed for 1 hour with a molten salt at 425°C containing a mixed salt of Here, the slow cooling shall be performed at a cooling rate of 0.5°C/min from a temperature T°C higher than the glass transition point by 30°C to 50°C to (T-300)°C.
If it is such a parent composition, the ion exchange rate is fast, and chemical strengthening can be carried out in a short time.
In the case of the chemically strengthened glass of the present invention, in the case of a plate shape (glass plate), the plate thickness (t) is not particularly limited, but from the viewpoint of enabling a remarkable strength improvement by chemical strengthening, for example, 2 mm or less. , preferably 1.5 mm or less, more preferably 1 mm or less, still more preferably 0.9 mm or less, particularly preferably 0.8 mm or less, and most preferably 0.7 mm or less. In addition, the thickness of the plate is, for example, 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.4 mm or more, and still more preferably, from the viewpoint of obtaining the effect of sufficient strength improvement by chemical strengthening treatment. is greater than 0.5 mm.
Further, the chemically strengthened glass of the present invention may have a shape other than a plate shape, for example, a shape with a rim having a different outer periphery thickness, depending on the applied product or use. Moreover, the said glass plate has two main surfaces and the end surface which adjoins these and forms plate|board thickness, and two main surfaces may form the mutually parallel flat surface. However, the form of a glass plate is not limited to this, For example, two main surfaces do not need to be mutually parallel, Furthermore, one or both all or part of two main surfaces may be a curved surface. More specifically, a flat glass plate without curvature may be sufficient as a glass plate, and the curved glass plate which has a curved surface may be sufficient as it, for example.
Further, in the present invention, the Young's modulus of the chemically strengthened glass is 70 GPa or more, and the compressive stress value (CS) on the outermost surface of the chemically strengthened glass.<sub>0</sub>) and the compressive stress value at a depth of 1 μm from the glass surface (CS<sub>1</sub>) is preferably 50 MPa or less. In this way, since it is hard to generate|occur|produce the curvature at the time of performing the grinding|polishing process of the glass surface after a chemical strengthening process, it is preferable.
The Young's modulus of the glass for chemical strengthening is more preferably 74 GPa or more, particularly preferably 78 GPa or more, and still more preferably 82 GPa or more. Although the upper limit of Young's modulus is not specifically limited, For example, it is 90 GPa or less, Preferably it is 88 GPa or less. The Young's modulus can be measured, for example, by an ultrasonic pulse method.
Also, CS<sub>0</sub>and CS<sub>1</sub>The difference between is preferably 50 MPa or less, more preferably 40 MPa or less, and still more preferably 30 MPa or less.
Also, CS<sub>0</sub>Silver becomes like this. Preferably it is 300 MPa or more, More preferably, it is 350 MPa or more, More preferably, it is 400 MPa or more. On the other hand, CS<sub>0</sub>Although the upper limit is not specifically limited, For example, it is 1200 MPa or less, Preferably it is 1000 MPa or less, More preferably, it is 800 MPa or less.
Also, CS<sub>1</sub>Silver becomes like this. Preferably it is 250 MPa or more, More preferably, it is 300 MPa or more, More preferably, it is 350 MPa or more. On the other hand, CS<sub>1</sub>Although the upper limit is not specifically limited, For example, it is 1150 MPa or less, Preferably it is 1100 MPa or less, More preferably, it is 1050 MPa or less.
The chemically strengthened glass of the present invention can be produced, for example, as follows. In addition, the following manufacturing method is an example in the case of manufacturing plate-shaped chemically strengthened glass.
First, the glass (glass for chemical strengthening) to be subjected to the above-described chemical strengthening treatment is prepared. For example, the raw material of each component of glass is combined, and it heat-melts in a glass melting kiln. Then, the glass is homogenized by bubbling, stirring, addition of a clarifier, etc., and it shape|molds into a glass plate of predetermined thickness by a conventionally well-known shaping|molding method, and is slow-cooled.
As a shaping|molding method of glass, a float method, a press method, a fusion method, and a down-draw method are mentioned, for example. In particular, the float method suitable for mass production is preferable. In addition, continuous molding methods other than the float method, that is, the fusion method and the down-draw method are also preferable.
Then, the shape|molded glass is grind|polished and grind|polished as needed, and a glass substrate is formed. In addition, when cutting a glass substrate to a predetermined shape and size, or performing chamfering of a glass substrate, before performing the chemical strengthening process mentioned later, if cutting or chamfering of a glass substrate is performed, by the subsequent chemical strengthening process Since a compressive stress layer is also formed in the end face, it is preferable.
Then, the chemically strengthened glass of the present invention can be manufactured by subjecting the formed glass substrate to a chemical strengthening treatment, followed by washing and drying.
In the chemical strengthening treatment, by contacting the glass by immersion or the like to a melt of a metal salt (eg, potassium nitrate) containing a metal ion (typically, Na ion or K ion) having a large ionic radius, Metal ions of ionic radius (typically Na ions or Li ions) are replaced with metal ions of large ionic radius.
Although the chemical strengthening process (ion exchange process) is not specifically limited, For example, it can perform by immersing glass in the molten salt heated to 360-600 degreeC for 0.1-500 hours. Moreover, as heating temperature of molten salt, 375-500 degreeC is preferable, and, as for the immersion time of the glass in molten salt, it is preferable that it is 0.3-200 hours.
Examples of the molten salt for performing the chemical strengthening treatment include nitrate, sulfate, carbonate, and chloride. Among these, lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, silver nitrate etc. are mentioned as a nitrate. Lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, silver sulfate etc. are mentioned as a sulfate. Lithium carbonate, sodium carbonate, potassium carbonate, etc. are mentioned as a carbonate. Lithium chloride, sodium chloride, potassium chloride, cesium chloride, silver chloride etc. are mentioned as a chloride. These molten salts may be used independently and may be used in combination of multiple types.
In the present invention, the treatment conditions of the chemical strengthening treatment are not particularly limited, and the properties and composition of the glass, the type of molten salt, and the surface compressive stress (CS) and the depth of the compressive stress layer required for the chemically strengthened glass finally obtained ( DOL), etc., may be selected in consideration of chemical strengthening properties and the like.
In the present invention, the chemical strengthening treatment may be performed only once, or the chemical strengthening treatment may be performed multiple times (multi-stage strengthening) under two or more different conditions. Here, for example, as the chemical strengthening treatment in the first step, after performing the chemical strengthening treatment under a condition in which the CS is relatively low, as the chemical strengthening treatment in the second step, the chemical strengthening treatment under the condition in which the CS is relatively high. By doing so, while increasing the outermost surface CS of the chemically strengthened glass, the integrated value of the compressive stress generated in the compressive stress layer can be suppressed to be slightly lower, and as a result, the internal tensile stress (CT) can be suppressed to a lower level.
In particular, in order to perform a chemical strengthening treatment at a high ion exchange rate, it is preferable to exchange Li ions in glass with Na ions (Li-Na exchange).
The method for producing chemically strengthened glass II of the present invention is a method for producing chemically strengthened glass in which at least two steps of ion exchange treatment are performed from the viewpoint of improving bending strength after damage, and KNO<sub>3</sub> NaNO in molten salt having a concentration of 60% by weight or more and used for the second stage ion exchange treatment<sub>3</sub> It is preferable that the density|concentration is 5 weight% or more.
KNO in the molten salt used for the first stage ion exchange treatment from the viewpoint of improving the flexural strength after scratching<sub>3</sub> It is preferable that it is 60 weight% or more, and, as for a density|concentration, it is more preferable that it is 70 weight% or more, 80 weight% or more, and 90 weight% or more in the following steps. In addition, the upper limit is not specifically limited, For example, 100 weight%, ie, KNO<sub>3</sub>A molten salt containing only the molten salt may be sufficient. Here, according to the ion exchange treatment in the first stage, Na-K exchange in which Na ions in the glass are mainly exchanged with K ions is performed.
In addition, from the viewpoint of improving the bending strength after damage, NaNO in the molten salt used for the ion exchange treatment in the second stage<sub>3</sub> The concentration is preferably 5% by weight or more, and in steps of 10% by weight or more, 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, It is more preferable that it is 80 weight% or more and 90 weight% or more. In addition, the upper limit is not specifically limited, For example, 100 weight%, ie, NaNO<sub>3</sub>A molten salt containing only the molten salt may be sufficient. Here, according to the ion exchange process of this 2nd stage|stage, Li-Na exchange which exchanges the Li ion in glass with Na ion at least is performed.
The chemically strengthened glass of the present invention is particularly useful as a cover glass used in mobile devices such as mobile phones, smartphones, personal digital assistants (PDAs), and tablet terminals. In addition, the cover glass of display devices such as televisions (TVs), personal computers (PCs), and touch panels that are not intended for portability, elevator walls, wall surfaces of buildings such as houses and buildings (full-surface display), window glass, etc. It is useful as a building material of a table top, the interior of an automobile or an airplane, etc., as a cover glass thereof, and also for applications such as a housing having a curved shape instead of a plate shape by bending or molding.
<b>Example</b>
Hereinafter, although an Example demonstrates this invention, this invention is not limited by these. In addition, about each measurement result in a table|surface, a blank shows that it is unmeasured.
(Production of chemically tempered glass)
Glasses of Examples 1 to 15 shown in Table 2 were produced as follows.
First, glass plates of glass 1, glass 3, glass 4, glass 6, and glass 7 having the compositions shown in Table 1 in terms of mole percentages on an oxide basis were prepared by melting in a platinum crucible. Glass raw materials generally used, such as oxide, hydroxide, carbonate, or nitrate, were appropriately selected and weighed so as to be 1000 g as glass. Then, the mixed raw materials were put in a platinum crucible, put into a resistance heating electric furnace at 1500 to 1700° C., melted for about 3 hours, defoamed, and homogenized. The obtained molten glass was made to flow into a shape material, and after hold|maintaining in the temperature of glass transition point +50 degreeC for 1 hour, it cooled to room temperature at the rate of 0.5 degreeC/min, and obtained the glass block. The obtained glass block was cut|disconnected and grind|ground, and finally both surfaces were processed into mirror surfaces, and the plate-shaped glass of a desired shape was obtained. In addition, the plate|board thickness t (mm) is shown in Table 2.
Glass plates having the compositions of Glass 2 and Glass 5 shown in Table 1 in terms of mole percentages based on oxides were produced in a float kiln. Glass raw materials such as oxides, hydroxides, carbonates or nitrates were appropriately selected and dissolved in a melting kiln, and formed to have a plate thickness of 1.1 to 1.3 mmt by a float method. The obtained plate glass was cut and ground, and finally both surfaces were processed into mirror surfaces, and the plate-shaped glass of a desired shape was obtained. In addition, the plate|board thickness t (mm) is shown in Table 2.
<tables num="1"><img file="KR20180098472A_D0001.tif" /></tables>
Subsequently, the chemically strengthened glasses of Examples 1 to 15 were obtained by subjecting Glass 1 to Glass 4 to chemical strengthening treatment under the conditions shown in Table 2.
Chemically strengthened glasses of Examples 31 to 38 were obtained by chemically strengthening the glass 6 and glass 7 under the conditions shown in Table 3.
In addition, Examples 1 to 9 and Examples 31 to 38 are examples of the chemically strengthened glass I of the present invention, and Examples 10 to 15 are comparative examples.
Further, chemically strengthened glasses of Examples 16 to 26 were obtained by subjecting Glass 1 or Glass 5 to chemical strengthening treatment under the conditions shown in Table 4.
Hereinafter, the chemically strengthened glasses of Examples 1 to 15 and Examples 31 to 38 will be described.
For chemically strengthened glass, surface compressive stress CS (unit: MPa), compressive stress layer thickness DOL (unit: μm), internal tensile stress CT (unit: MPa), compressive stress value at a depth of x μm from the glass surface CS<sub>x</sub>(Unit: MPa), Area of the compressive stress layer Sc (Unit: MPa μm), Sc/t (Unit: MPa), Area of the inner tensile layer St (Unit: MPa μm), St/t (Unit: MPa) ), ΔCS<sub>100-90</sub>(Unit: MPa/), CS<sub>DOL-20</sub>(unit: MPa) and ΔCS<sub>DOL-20</sub>(unit: MPa/μm) was measured or calculated.
In addition, CS is the value CT by the following two types of measurement methods<sub>F</sub> and CS<sub>A</sub>By , it is defined as follows. Compressive stress value at a depth of x μm from the glass surface (CS<sub>x</sub>) is the same for
CS=CS<sub>F</sub>=1.28×CS<sub>A</sub>
Here, CS<sub>F</sub>is a value measured by a surface stress meter FSM-6000 manufactured by Orihara Seisakusho Co., Ltd., and obtained by the attached program FsmV of the surface stress meter. Also, CS<sub>A</sub>is a value measured by the method using the above-mentioned birefringent imaging system Abrio-IM manufactured by Tokyo Instruments Co., Ltd. and a thin sample.
In addition, CT is the value CT by the following two types of measurement methods<sub>F</sub> and CT<sub>A</sub>By , it is defined as follows.
CT = CT<sub>F</sub>=1.28×CT<sub>A</sub>
Here, CT<sub>F</sub>is a value measured by a surface stress meter FSM-6000 manufactured by Orihara Seisakusho Co., Ltd., and obtained by the attached program FsmV of the surface stress meter. Also, CT<sub>A</sub>is a value measured by the method using the above-mentioned birefringent imaging system Abrio-IM manufactured by Tokyo Instruments Co., Ltd. and a thin sample.
In addition, the St value is the value St measured by the surface stress meter FSM-6000 manufactured by Orihara Seisakusho and analyzed by the attached program FsmV.<sub>F</sub>, or the value St obtained by measurement using the birefringent imaging system Abrio-IM and flaked samples.<sub>A</sub>is defined as follows using
St=St<sub>F</sub>=1.515×St<sub>A</sub>
(Indenter indentation test)
For chemically strengthened glass having a size of 25 mm × 25 mm × thickness 0.8 mm (800 μm), using a diamond indenter having an indenter angle of 60 degrees facing angle, in an indenter indentation test in which a load of 5 to 10 kgf is held for 15 seconds Thus, the chemically strengthened glass was destroyed, and the number of fragments (number of fractures) of the glass after destruction was measured. These results are shown in Table 2.
From these results, the chemically strengthened glass of Examples 1 to 9 and Examples 11 to 14 had a number of fractures of 20 or less in the destructive test by the indenter indentation test, and was a glass with high safety when destroyed. On the other hand, the chemically strengthened glass of Examples 10 and 15 greatly exceeded 20 pieces, and was a glass lacking in safety when destroyed.
(Drop test on sand)
Then, the chemically strengthened glass was subjected to a drop test on sand by the following test method to measure the average crack height (unit: mm).
3 is a schematic diagram showing a test method for a drop test on sand.
First, chemically tempered glass 13 (50 mm × 50 mm × thickness 0.8 (mm)) was applied to a rigid nylon MOC plate 11 (50 mm × 50 mm × thickness 18 mm, weight: 54 g) with a sponge double-sided tape 12 (three meals). It was joined through #2310 by Sui Chemical Co., Ltd., 50 mm x 50 mm x thickness 3 mm) to prepare a measurement sample (1). Next, 1 g of silica sand 22 (No. 5 silica sand manufactured by Takeori Co., Ltd.) is evenly spread on the SUS plate 21 of 15 cm×15 cm size, and the prepared measurement sample 1 is applied to the chemically strengthened glass 13 It was dropped from a predetermined height (fall height) to the surface of the SUS plate 21 on which the silica sand 22 was sprinkled. The drop test was carried out by starting from a drop height of 10 mm, increasing the height by 10 mm, and the height at which the chemically strengthened glass 13 cracked was defined as the crack height (unit mm). The drop test was performed 5 to 10 times for each example, and the average value of the crack height in the drop test was taken as the average crack height (unit: mm). These results are shown in Table 2.
In Fig. 4, the compressive stress value CS at a depth of 90 µm from the glass surface regarding chemically strengthened glass<sub>90</sub>A graph plotting the relationship between (unit: MPa) and average crack height (unit: mm) is shown.
From Fig. 4, the average crack height is the internal compressive stress CS<sub>90</sub>It can be seen that the correlation with CS<sub>90</sub>If it is 25 MPa or more, it turns out that the average crack height will be about 300 mm or more, and the improvement of the intensity|strength (acute-angle flaw strength) can be achieved significantly.
In addition, from Table 2, when the value Sc/t (MPa) obtained by dividing the area Sc (MPa·μm) of the compressive stress layer by the plate thickness t (μm) is 28 or more, the average crack height is about 300 mm or more, It can be seen that an improvement in strength (acute angle scratch strength) can be achieved.
<Four-point bending test after or without scratches>
With respect to chemically strengthened glass having a size of 40 mm × 5 mm × thickness 0.8 (mm), by pressing for 15 seconds with a load of 0.5Kgf, 1Kgf or 2Kgf by applying a diamond indenter (face-to-face indenter angle: 110°) to chemically strengthened glass without scratching , the glass surface was scratched. Next, a four-point bending test was performed under the conditions of a lower span of 30 mm, an upper span of 10 mm, and a crosshead speed of 0.5 mm/min, and the breaking stress (MPa) was measured at the time of non-scratches and in each of the conditions of scratches. Table 2 shows the breaking stress values (bending strength, unit: MPa) when the four-point bending test is performed at the time of non-scratches and under each damage condition.
5 , ΔCS for the chemically strengthened glass of Examples 4, 6, 8 to 10 and 15<sub>100</sub><sub>-90</sub>The graph which plotted the relationship between (unit: MPa/micrometer) and the breaking stress (MPa) in each flaw condition is shown.
As described above, when the smartphone is dropped, a tensile stress of about 150 MPa is generated on the glass surface. When it has a breaking stress of 150 MPa or more even after a scratch, the crack of the cover glass at the time of a fall can be prevented. From Figure 5, ΔCS<sub>100</sub><sub>-90</sub>When this is 0.4 or more, it turns out that the bending stress after a flaw at a load of 0.5 Kgf and 1 Kgf becomes 150 MPa or more. Also, ΔCS<sub>100</sub><sub>-90</sub>When this 0.9 or more, it turns out that the bending stress after a flaw in 2Kgf will be 150 MPa or more.
(ion exchange rate)
Glass 1 to Glass 4 were subjected to chemical strengthening treatment under the chemical strengthening treatment conditions described at the bottom of Table 2, and DOL (µm) in each case was measured. Their results are shown together in Table 2. In addition, for example, "1mmt KNO<sub>3</sub> DOL (μm) when tempered at 400°C for 1 hour" is KNO for glass with a thickness of 1 mm<sub>3</sub>The DOL (µm) when chemical strengthening treatment was performed using a molten salt of 400°C for 1 hour is shown.
<tables num="2"><img file="KR20180098472A_D0002.tif" /></tables>
<tables num="3"><img file="KR20180098472A_D0003.tif" /></tables>
Hereinafter, the chemically strengthened glasses of Examples 16 to 25 will be described.
(CS<sub>x</sub>measurement of)
For each chemically strengthened glass of Examples 16 to 25, the compressive stress value CS at a depth of x μm from the glass surface<sub>x</sub>(unit: MPa) was measured by the method using the above-mentioned birefringent imaging system Abrio-IM manufactured by Tokyo Instruments Co., Ltd. and a thin piece sample. These results are shown in Table 4. In addition, for the chemically strengthened glass of Example 26, CS and DOL were measured with a surface stress meter (manufactured by Orihara Seisakusho, FSM-6000). The CS was 95.7 MPa and the DOL was 34.6 μm.
(measured by EPMA)
For chemically strengthened glass, the following N0, NM, Nh, K0, KM and Kh are calculated from the Na ion concentration profile and K ion concentration profile obtained using an electron probe micro analyzer (EPMA), respectively, Table 1 shows. A cross section of each chemically strengthened glass was mirror polished, and C was coated to about 30 nm to be subjected to EPMA analysis. EPMA was performed using JXA-8500F manufactured by Nippon Electronics Co., Ltd., acceleration voltage 15 kV, probe current 30 nA, probe diameter 1 µm phi, step interval 1 µm, measurement time 1 s, spectral crystal TAPH (Na Kα line, peak position: 129.55 mm) , and PETH (K Kα ray, peak position: 119.75 mm) to obtain a profile of the number of characteristic X-ray counts of each element. Furthermore, the count number of each element in the plate|board thickness center of a sample was converted into the weight % in a sample composition, and it was set as the ion concentration profile.
N0: The value at the outermost surface in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)
NM: The maximum value in the Na ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)
Nh: The central value of the plate thickness in the Na ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is Na<sub>2</sub>Value converted to O (wt%)
K0: The value at the outermost surface in the K ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%)
KM: The maximum value in the K ion concentration profile in the sheet thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%)
Kh: The central value of the plate thickness in the K ion concentration profile in the plate thickness direction of the chemically strengthened glass measured by EPMA is K<sub>2</sub>Value converted to O (wt%)
In addition, from the above results, N0/Nh, NM/Nh, N0/NM, N0-Nh, NM-Nh, N0-NM, K0/Kh, KM/Kh, K0/KM and KM-Kh are calculated respectively, Table 1 shows.
(4-point bending test after scratches or when not scratched)
The glass surface was damaged by pressing a diamond indenter (indentation angle of facing angle: 110°) with respect to chemically strengthened glass for 15 seconds under a load of 0.5Kgf, 1Kgf, 1.5Kgf or 2Kgf. Next, a four-point bending test was performed under the conditions of a lower span of 30 mm, an upper span of 10 mm, and a crosshead speed of 0.5 mm/min, and the breaking stress (MPa) in each scratch condition was measured. Table 1 shows the breaking stress values (bending strength, unit: MPa) in the case of performing a four-point bending test at the time of non-scratches and at the time of each indenter press-in load.
(Drop test on sand)
In addition, the chemically strengthened glass was subjected to a drop test on sand by the test method described above, and the average crack height (unit: mm) was measured. A result is shown in Table 4.
For Examples 16, 18, 21, 22, 24, and 25, the DOL was 100 µm or more in each of the examples, and the average crack height in the above-mentioned drop test on sand was 300 mm or more. In Example 26, the DOL was 100 μm or less, and the average crack height was 129 mm. When the DOL is 100 µm or more, it is shown that the strength is improved due to the drop test resistance on sand, and it can be seen that the strength improvement with respect to the breakage caused by the sharp-angle scratches required for the cover glass can be expected.
(Indenter indentation test)
With respect to chemically strengthened glass having a size of 25 mm × 25 mm × thickness 0.8 mm, using a diamond indenter having an indenter angle of 60 degrees opposite to each other, by an indenter indentation test holding a load of 3 to 10 kgf for 15 seconds, chemical The tempered glass was broken, and the number of fractures of the chemically tempered glass after breaking was measured. These results are shown in Table 4.
<tables num="4"><img file="KR20180098472A_D0004.tif" /></tables>
6, the bending strength and CS after scratching under the load of 0.5Kgf or 1Kgf<sub>20</sub>A graph plotting the relationship between In addition, in Fig. 7, the bending strength and CS after being scratched under the load of 0.5Kgf or 1Kgf.<sub>40</sub>shows a plot of the relationship between As described above, if the post-damage bending strength is 200 MPa or more, the failure rate when used as a cover glass for a smartphone or tablet PC can be improved. As can be seen from Figs. 6 and 7, the compressive stress value (CS) at a depth of 20 to 40 μm from the glass surface.<sub>20</sub> to CS<sub>40</sub>) and the post-scratches bending strength, there is a strong correlation, and the higher the compressive stress value at a depth of 20 to 40 µm from the glass surface, the higher the post-scratch flexural strength tends to be obtained. and CS<sub>20</sub>Ina CS<sub>40</sub>It turns out that when this 60 MPa or more, bending strength after a flaw of 200 MPa or more can be achieved.
In addition, in FIG. 8, NM/Nh and CS<sub>20</sub> or CS<sub>40</sub>A graph plotting the relationship between According to this, as NM/Nh increases, CS<sub>20</sub>Ina CS<sub>40</sub>tends to increase, and if NM/Nh is 1.8 or more, CS<sub>20</sub>Ina CS<sub>40</sub>can be 60 MPa or more, that is, it can be seen that 200 MPa or more can be achieved after the bending strength.
In addition, in FIG. 9, N0/Nh and CS<sub>20 </sub>or CS<sub>40</sub>A graph plotting the relationship between According to this, as N0/Nh increases, CS<sub>20</sub>Ina CS<sub>40</sub>tends to increase, and if N0/Nh is 0.8 or more, CS<sub>20</sub>Ina CS<sub>40</sub>can be 60 MPa or more, that is, it can be seen that 200 MPa or more can be achieved after the bending strength.
In addition, in FIG. 10, N0/NM and CS<sub>20 </sub>or CS<sub>40</sub>A graph plotting the relationship between According to this, as N0/NM increases, CS<sub>20</sub>Ina CS<sub>40</sub>tends to increase, and if N0/NM is 0.4 or more, CS<sub>20</sub>Ina CS<sub>40</sub>can be 60 MPa or more, that is, it can be seen that 200 MPa or more can be achieved after the bending strength.
In addition, the chemically strengthened glasses of Examples 16, 21 and 22 had a KM/Kh of 3 or more, and had a bending strength of 400 MPa or more, which is required from the viewpoint of securing the strength of the cover glass.
11, NM-Nh (unit: wt%) and CS<sub>20 </sub>or CS<sub>40</sub>A graph plotting the relationship between According to this, as NM-Nh increases, CS<sub>20</sub>Ina CS<sub>40</sub>tends to increase, and when NM-Nh is 2.2 wt% or more, CS<sub>20</sub>Ina CS<sub>40</sub>can be 60 MPa or more, that is, it can be seen that 200 MPa or more can be achieved after the bending strength.
In addition, in Fig. 12, N0-Nh and CS<sub>20 </sub>or CS<sub>40</sub>A graph plotting the relationship between According to this, as N0-Nh increases, CS<sub>20</sub>Ina CS<sub>40</sub>tends to increase, and when N0-Nh is -0.4 wt% or more, CS<sub>20</sub>Ina CS<sub>40</sub>can be 60 MPa or more, that is, it can be seen that 200 MPa or more can be achieved after the bending strength.
In addition, in FIG. 13, N0-NM and CS<sub>20 </sub>or CS<sub>40</sub>A graph plotting the relationship between According to this, as N0-NM increases, CS<sub>20</sub>Ina CS<sub>40</sub>tends to increase, and when N0-NM is -3.5 wt% or more, CS<sub>20</sub>Ina CS<sub>40</sub>can be 60 MPa or more, that is, it can be seen that 200 MPa or more can be achieved after the bending strength.
Further, the chemically strengthened glasses of Examples 16, 21 and 22 had a KM-Kh of 3 wt% or more, and had a bending strength of 400 MPa or more, which is required from the viewpoint of securing the cover glass strength reliability.
Although this invention was demonstrated in detail with reference to the specific form, it is clear for those skilled in the art that various changes and correction are possible without departing from the mind and range of this invention.
In addition, this application is a Japanese patent application filed on January 21, 2016 (Japanese Patent Application 2016-01002), a Japanese Patent Application filed on October 18, 2016 (Japanese Patent Application 2016-204746) and 2016 It is based on the Japanese patent application (Japanese patent application 2016-204747) for which it applied on October 18, The whole is used by reference.
One measurement sample 11 MOC Edition 12 Sponge double-sided tape 13 Chemically Tempered Glass 21 SUS version 22 quartz sand
18 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10 Sheet 11 Sheet 12 Sheet 13 Sheet 14 Sheet 15 Sheet 16 Sheet 17 Sheet 18
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128 members in 7 offices
Members128
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| Annual fee paymentFPAY | FPAY | |
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| Application refused [patent]X091 | X091 | |
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| Request for examinationA201 | A201 |
Numbers
- Publication
- 10-2018-0098472
- Application
- 107016470
Titles5
- Korean
- 화학 강화 유리 및 화학 강화 유리의 제조 방법
- English
- CHEMICALLY STRENGTHENED GLASS AND METHOD FOR MANUFACTURING CHEMICALLY STRENGTHENED GLASS
- English
- Chemically Tempered Glass and Method for Manufacturing Chemically Tempered Glass
- Unlabeled
- 화학 강화 유리 및 화학 강화 유리의 제조 방법{CHEMICALLY STRENGTHENED GLASS AND METHOD FOR MANUFACTURING CHEMICALLY STRENGTHENED GLASS}
- Unlabeled
- Chemically strengthened glass and chemically strengthened glass manufacturing method
Classification
- CPC, 10
- C03C21/002
- C03C3/087
- C03C3/097
- C03C3/091
- C03C3/085
- C03C4/18
- Y02P40/57
- C03C3/083
- C03C21/00
- C03C3/093
- IPC, 5
- C03C21 00
- C03C3 087
- C03C3 091
- C03C3 097
- C03C4 18