JP2012193090A - Glass plate and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass plate constituted by cutting after chemically reinforcing and having excellent quantity when assembling to other members.SOLUTION: The glass plate 10 is constituted by cutting after chemically reinforcing and has: a front surface layer 21 and a rear surface layer 22 in which compressive stress remains; an intermediate layer 23 formed between the front surface layer 21 and the rear surface layer 22 in which tensile stress remains; and areas 31, 32 in which compressive stress remains and an area 33 in which tensile stress remains, in side end surface 13 being a cut surface. In the glass plate, a border line 40 of the side end surface 13 being the cut surface and a surface 11 includes a straight line like part 41, the straight line like part 41 satisfies the formula of d/L≤2.0×10, wherein a maximum distance between a point on the straight line-like part 41 and a virtual straight line 51 connecting both the ends of the straight line-like part 41 is d (mm) and the length of the virtual straight line 51 is L (mm).

Description

  The present invention relates to a glass plate cut after chemical strengthening and a method for producing the same.

  In recent years, in a portable device such as a mobile phone or a PDA, a cover glass (protective glass) is often used in order to enhance the protection and aesthetics of a display (including a touch panel). A glass substrate is widely used as a display substrate.

  On the other hand, thinning and lightening of portable devices are progressing, and thinning of glass plates used for portable devices is progressing. Since the strength of the glass plate decreases as the glass plate becomes thinner, techniques for chemically strengthening the glass plate have been developed to compensate for the lack of strength of the glass plate.

  Chemical strengthening is a method of forming a surface layer and a back surface layer in which compressive stress remains by ion exchange of the surface and the back surface of glass. As a reaction, an intermediate layer in which a tensile stress remains is formed between the front surface layer and the back surface layer.

  When mass-producing chemically strengthened glass plates, it is more efficient to chemically temper glass plates that are larger than the product size and then cut and take multiple faces rather than chemically strengthening each product size glass plate one by one. is there.

  Therefore, as a method of cutting the chemically strengthened glass plate, a laser beam is irradiated to a predetermined region on the surface of the chemically strengthened glass plate, and the predetermined region on the surface is moved along the planned cutting line, thereby cracking due to thermal stress. There has been proposed a method of cutting by forming (see, for example, Patent Document 1).

JP 2008-247732 A

  By the way, in the above-mentioned Patent Document 1, since a carbon dioxide laser is used as a light source of laser light, most of the laser light is absorbed as heat near the surface of the chemically strengthened glass plate, and a predetermined region (laser irradiation region) on the surface is absorbed. ), A tensile stress larger than the residual tensile stress is generated. As a result, the crack formed at the time of cutting tends to extend rapidly in an unintended direction beyond a predetermined region.

Therefore, conventionally, when the boundary line between the side end surface, which is a cut surface, and the surface includes a linear portion, the linear portion does not completely overlap with a virtual straight line connecting both ends of the linear portion. When the maximum distance between the upper point and the virtual straight line was d (mm) and the length of the virtual straight line was L (mm), d / L exceeded 2.0 × 10 ⁻³ .

If d / L exceeds 2.0 × 10 ⁻³ , the linearity of the linear portion is not sufficient, and various problems occur when assembled to other members. For example, when the frame body (for example, a housing of a portable device) is fitted into the opening, the glass plate is locally deformed, and clear perspective distortion and reflection distortion are generated.

  This invention is made | formed in view of the said subject, Comprising: It cuts after chemical strengthening, Comprising: It aims at providing the glass plate excellent in the quality at the time of the assembly | attachment to another member.

In order to solve the above object, the present invention provides:
It is a cut surface having a surface layer and a back surface layer that are cut after chemical strengthening and in which compressive stress remains, and an intermediate layer that is formed between the surface layer and the back surface layer and in which tensile stress remains. In the glass plate having a region where compressive stress remains and a region where tensile stress remains on the side end face,
The boundary line between the side end face that is the cut surface and the surface includes a linear portion,
The linear portion has a maximum distance between a point on the linear portion and a virtual straight line connecting both ends of the linear portion as d (mm), and the length of the virtual straight line is L (mm). Then, the glass plate characterized by satisfy | filling the formula of d / L <= 2.0 * 10 < ^-3 > is provided.

  According to the present invention, it is possible to provide a glass plate which is cut after chemical strengthening and has excellent quality when assembled to another member.

It is a perspective view of the glass plate which concerns on the 1st Embodiment of this invention. 3 is a side view of a main part of the glass plate 10. FIG. 2 is a schematic diagram showing a thickness direction distribution of residual stress of a glass plate 10. FIG. It is explanatory drawing (1) of the manufacturing method of the glass plate which concerns on the 2nd Embodiment of this invention. It is explanatory drawing of the stress distribution in the cross section of the chemically strengthened glass plate before dielectric heating. It is sectional drawing along the AA line of FIG. It is sectional drawing along the BB line of FIG. It is explanatory drawing (2) of the manufacturing method of the glass plate which concerns on the 2nd Embodiment of this invention. It is explanatory drawing (1) of the manufacturing method of the glass plate which concerns on the 3rd Embodiment of this invention. It is explanatory drawing of the stress distribution in the cross section of the chemically strengthened glass plate before laser heating. It is sectional drawing along the AA line of FIG. It is sectional drawing along the BB line of FIG. It is explanatory drawing (2) of the manufacturing method of the glass plate which concerns on the 3rd Embodiment of this invention.

  Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below. The present invention can add various modifications and replacements to the embodiments described below without departing from the scope of the present invention.

[First Embodiment]
1st Embodiment is related with the glass plate formed by cut | disconnecting after chemical strengthening.

  FIG. 1 is a perspective view of a glass plate according to the first embodiment of the present invention. FIG. 2 is a side view of the main part of the glass plate 10.

  The glass plate 10 is cut after chemical strengthening. Since this glass plate 10 has high production efficiency compared with what is chemically strengthened after a cutting | disconnection, manufacturing cost is low. The cutting method will be described in the second and third embodiments.

Chemical strengthening is a method of ion-exchanging the front surface and back surface of glass to form a front surface layer and a back surface layer in which compressive stress remains. In chemical strengthening, ions having a small ionic radius (for example, Li ions and Na ions) contained in glass are replaced with ions having a large ionic radius (for example, K ions). The treatment liquid for ion exchange is not particularly limited, and for example, KNO ₃ molten salt is used.

  In chemical strengthening, an intermediate layer in which a tensile stress remains is formed between the surface layer and the back surface layer as a reaction for forming a surface layer and a back surface layer in which a compressive stress remains.

  Therefore, the glass plate 10 cut after the chemical strengthening is formed between the surface layer 21 and the back surface layer 22 where the compressive stress remains, and between the surface layer 21 and the back surface layer 22, and the intermediate where the tensile stress remains. Layer 23.

  FIG. 3 is a schematic diagram showing a thickness direction distribution of residual stress of the glass plate 10. As shown in FIG. 3, the compressive stress remaining in the front surface layer 21 and the back surface layer 22 tends to gradually decrease from the front surface 11 and the back surface 12 toward the inside. Further, the tensile stress remaining in the intermediate layer 23 is substantially constant.

3, S1 is the maximum residual compressive stress of the surface layer 21, S2 is the maximum residual compressive stress of the back surface layer 22, D1 is the thickness of the surface layer 21, D2 is the thickness of the back surface layer 22, and D is the thickness of the glass plate 10. Thickness and T indicate the average residual tensile stress of the intermediate layer 23, respectively. S1, S2 (S2 = S1), D1, D2 (D2 = D1), and T can be adjusted according to the tempering treatment conditions. The concentration and temperature of the chemical strengthening treatment liquid and the glass for chemical strengthening are used as the treatment liquid. It can be adjusted by the immersion time. Further, S1, S2, D1, and D2 can be measured with a commercially available surface stress meter, and T can be calculated by substituting the measurement result and D into the following equation (1).
T = (S1 × D1 / 2 + S2 × D2 / 2) / (D−D1−D2) (1)
For D, data measured with a micro gauge or the like is used.

  The front surface layer 21 and the back surface layer 22 of the present embodiment have the same maximum residual compressive stress and the same thickness, but may have different maximum residual tensile stresses and different thicknesses.

  The glass plate 10 has the surface 11, the back surface 12, and the side end surfaces 13-16 which are a cut surface, for example, as shown in FIG.

  Each of the front surface 11 and the back surface 12 is a flat surface that is immersed in a chemical strengthening treatment solution. The front surface 11 and the back surface 12 are each formed in a rectangular shape, for example. Here, the “rectangular shape” means a square shape or a rectangular shape, and includes a shape in which a corner portion is rounded.

  In addition, there is no restriction | limiting in the shape of the surface 11 and the back surface 12, For example, polygonal shapes, such as a triangular shape, may be sufficient.

  The side end surfaces 13 to 16 are formed substantially perpendicular to the front surface 11 and the back surface 12. Therefore, the boundary line 40 between the side end surfaces 13 to 16 and the surface 11 and the boundary line between the side end surfaces 13 to 16 and the back surface 12 have substantially the same size and shape.

  The side end surfaces 13 to 16 may be flat surfaces. In the present embodiment, all of the side end surfaces 13 to 16 are cut surfaces, but at least one of the side end surfaces 13 to 16 may be a cut surface.

  Next, the configuration of the side end face 13 will be described with reference to FIG. The configuration of the remaining side end surfaces 14 to 16 is the same as the configuration of the side end surface 13 and will not be described.

  As shown in FIG. 1, the side end face 13 includes regions 31 and 32 where compressive stress remains and a region 33 where tensile stress remains.

  The region 31 where the compressive stress remains is constituted by the side end face of the surface layer 21, the region 32 where the compressive stress remains is constituted by the side end face of the back surface layer 22, and the region 33 where the tensile stress remains is the side end face of the intermediate layer 23. It consists of Therefore, the region 33 where the tensile stress remains is formed between the two regions 31 and 32 where the compressive stress remains.

  In addition, the structure of the side end surface 13 is not limited to this. For example, when the side end surfaces 14 and 16 adjacent to the side end surface 13 are not cut surfaces but are surfaces immersed in a chemical strengthening treatment liquid, the region where the tensile stress remains in the side end surface 13 is compressed stress. Surrounded by the remaining area.

  A boundary line (cutting line) 40 between the side end faces 13 to 16 and the surface 11 which is a cutting plane includes four linear portions 41 to 44. Note that the boundary line 40 only needs to include one or more linear portions, and may further include a curved portion.

  Next, the structure of the linear part 41 is demonstrated based on FIG. 1 and FIG. Since the structure of the remaining linear parts 42-44 is the same as that of the linear part 41, description is abbreviate | omitted.

  The linear portion 41 is a boundary portion between the side end surface 13 that is a cut surface and the surface 11, and constitutes one side of the outer periphery of the rectangular surface 11.

  Although it is desirable that the straight line portion 41 completely overlaps with the virtual straight line 51 that connects both ends of the straight line portion 41, the straight line portion 41 may be slightly shifted to the left or right side from the virtual straight line 51 except for both ends. May be crossed.

The straight portion 41 has a maximum distance between a point on the straight portion 41 and the virtual straight line 51 d (mm), and the length of the virtual straight line 51 is L (mm), d / L ≦ 2 0 × 10 ⁻³ is satisfied. Here, the “distance” is a distance in a direction orthogonal to the virtual straight line 51. The “maximum distance” is obtained by measuring a distance between a point farthest from the virtual straight line 51 on the linear portion 41 and the virtual straight line 51.

By setting the upper limit of d / L to 2.0 × 10 ⁻³ , good linearity can be obtained, and good quality can be obtained when assembled to other members. For example, it is possible to suppress the perspective distortion and the reflection distortion of the glass plate 10 to the extent that it is difficult to visually recognize when the frame body (for example, the casing of the mobile device) is fitted into the opening. The upper limit value of d / L is preferably 1.5 × 10 ⁻³ , more preferably 1.0 × 10 ⁻³ .

  In order to sufficiently obtain the above effects, the maximum distance is preferably 200 μm or less. The maximum distance is set according to the length of the virtual straight line 51 and the like, more preferably 150 μm or less, and further preferably 100 μm or less.

  At an arbitrary point on the linear portion 41, the angle θ formed by the side end face 13 that is a cut surface and the surface 11 is, for example, 82 to 98 °, preferably 84 to 96 °, more preferably 87 to 93 °. . By setting the angle θ to be 82 to 98 °, it can be assembled to other members with high accuracy.

  The thickness of the glass plate 10 is appropriately set according to the use of the glass plate 10 and the like. For example, the thickness of the glass plate 10 is 0.4 to 1.8 mm. By setting the thickness of the glass plate 10 to 0.4 mm or more, the rigidity of the glass plate 10 can be sufficiently increased. On the other hand, the glass plate 10 can be sufficiently reduced in thickness and weight by setting the thickness of the glass plate 10 to 1.8 mm or less. The thickness of the glass plate 10 is preferably 0.6 to 1.2 mm, more preferably 0.7 to 1.1 mm.

The composition of the glass plate 10 is selected according to the use of the glass plate 10. For example, as for the glass plate 10 before chemical strengthening, the content rate of each following component is illustrated on the basis of an oxide.
(Composition 1: expressed in mole percentage) SiO ₂ 50-74%, Al ₂ O ₃ 1-10%, Na ₂ O 6-14%, K ₂ O 3-15%, MgO 2-15% , CaO 0 to 10%, ZrO ₂ 0 to 5%, the total content of SiO ₂ and Al ₂ O ₃ is 75% or less, the total content of Na ₂ O and K ₂ O Na ₂ O + K ₂ O is 12 to 25%, and the total content of MgO and CaO is 7 to 15%.
(Composition 2: mole percentage display) a SiO ₂ 61 - 66%, the _Al 2 _{O 3 6~12%,} the MgO 7 to 13%, a Na ₂ O 9 to 17%, the _{K 2} O 0 to 7% If it contains ZrO2 _, its content is 0.8% or less.
(Composition 3: mass percentage) of SiO ₂ 75.5~85.5%, the MgO 1 to 8%, the CaO 0 to 7%, the _Al 2 _{O 3 0~5%,} a Na ₂ O. 10 to 22.5%, the content of MgO is greater than the content of CaO, the total content of MgO and CaO (MgO + CaO) is 8% or less, and the total content of MgO, CaO and Na ₂ O is 24 The ratio obtained by dividing the MgO and CaO content (MgO + CaO) by the Na ₂ O content is 0.45 or less.
The glass for chemical strengthening is produced by a float method, a fusion down draw method, a slit down draw method, a redraw method, or the like.

  Although the use of the glass plate 10 is not specifically limited, For example, it may be a cover glass for a display incorporated in a portable device, a substrate, or the like.

[Second Embodiment]
The second embodiment relates to a method of manufacturing the glass plate 10 described above, and particularly relates to a method of cutting a chemically strengthened glass plate (hereinafter referred to as “chemically strengthened glass plate”).

  FIG. 4 is an explanatory diagram of the glass plate manufacturing method according to the second embodiment of the present invention.

  The glass plate manufacturing method includes a step of dielectrically heating the predetermined region 130 at a temperature equal to or lower than the annealing point by applying an alternating electric field to the predetermined region 130 of the chemically strengthened glass plate 110. The reason why the heating temperature is set to a temperature equal to or lower than the annealing point is that when the glass is heated to a temperature exceeding the annealing point, the glass flows in a viscous manner so as to relieve the thermal stress.

  In this step, the chemically strengthened glass plate 110 is cut by moving the predetermined region 130 along the planned cutting line 113 on the surface 111 of the chemically strengthened glass plate 110.

  The planned cutting line 113 is a virtual line scheduled to be a cutting part. The planned cutting line 113 has a shape according to the purpose, includes one or more linear portions, and may further include a curved portion. For example, the planned cutting line 113 has one straight portion as shown in FIG.

  A scribe line (groove line) is not formed in advance on the entire cutting line 113. The scribe line may be formed in advance, but in this case, the number of steps increases, and the work is complicated. Further, if the scribe line is formed in advance, the glass may be lost.

  The starting end of the planned cutting line 113 intersects with the outer periphery of the surface 111 of the chemically strengthened glass plate 110. An initial crack serving as a starting point for cutting is formed in advance at the starting end of the planned cutting line 113 and in the vicinity thereof. The method for forming the initial crack may be a general method, for example, a cutter, a file, or a laser. In order to reduce the number of processes, there is no need for initial cracks.

  The end of the planned cutting line 113 intersects with the outer periphery of the surface 111 of the chemically strengthened glass plate 110. Note that the end of the planned cutting line may intersect the middle of the planned cutting line. In this case, the planned cutting line is set in a P-shape, for example.

  In order to apply an alternating electric field to the predetermined region 130 of the chemically strengthened glass plate 110, the first and second electrodes 131 and 132 are arranged to face each other with the chemically strengthened glass plate 110 interposed therebetween.

  Each of the first and second electrodes 131 and 132 may be formed in a needle shape, and may have a tip portion tapered toward the chemically strengthened glass plate 110. As a result, the predetermined region 130 to which the alternating electric field is applied is narrowed, and the cutting accuracy is increased.

  As the first and second electrodes 131 and 132 become shorter, leakage current can be reduced and power loss can be reduced, but on the other hand, handling properties are deteriorated. The lengths of the first and second electrodes 131 and 132 are determined in consideration of power loss and handling properties, and are, for example, 1 to 300 mm, preferably 2 to 100 mm, more preferably 3 to 50 mm.

  The first and second electrodes 131 and 132 have an average diameter corresponding to the length and power. An average diameter is 0.1-20 mm, for example, Preferably it is 0.2-10 mm, More preferably, it is 0.4-4 mm.

  The first and second electrodes 131 and 132 may be spaced apart from the chemically strengthened glass plate 110. Thereby, damage due to contact can be prevented. Moreover, since a discharge arises between the 1st and 2nd electrodes 131 and 132 and the chemically strengthened glass plate 110 by this, heating efficiency improves.

  In order to stabilize discharge, the ambient atmosphere around the first and second electrodes 131 and 132 is preferably an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere, and more preferably a reduced pressure atmosphere.

  The first and second electrodes 131 and 132 are electrically connected via a circuit 133. The second electrode 132 is preferably grounded.

  The circuit 133 includes a high-frequency power source 134 that applies an alternating current to the first electrode 131, a modulator 135 that modulates the frequency, duty ratio, and voltage of the alternating current applied to the first electrode 131.

  The high-frequency power source 134 applies an alternating current to the first electrode 131 to form an alternating electric field between the first electrode 131 and the second electrode 132, and consequently generates an alternating electric field in the predetermined region 130. Form. The predetermined region 130 is dielectrically heated by an alternating electric field.

The dielectric heating amount P per unit volume of the predetermined region 130 is expressed by the equation P = ε ₀ × ε _r × tan δ × 2π × f × (V / t) ² . In the equation, ε ₀ is the dielectric constant of vacuum, ε _r is the relative dielectric constant of the chemically strengthened glass plate 110, δ is the dielectric loss angle, f is the frequency of the alternating current applied to the first electrode 131, and V is the first AC voltage applied to the electrode 131, t indicates the thickness of the chemically strengthened glass plate 110. As is apparent from the above equation, the dielectric heating amount P can be adjusted by the frequency f, the alternating voltage V, and the like.

The frequency f and the alternating voltage V are appropriately set according to the cutting speed of the chemically strengthened glass plate 110 and the like. The frequency f is, for example, 10 ³ to 10 ¹⁰ Hz, preferably 10 ⁴ to 10 ⁹ Hz, and more preferably 10 ⁵ to 10 ⁸ Hz. The AC voltage V is, for example, 10 to 10 ⁷ V, preferably 10 ² to 10 ⁶ V, and more preferably 10 ² to 10 ⁵ V.

  In this embodiment, since the chemically strengthened glass plate 110 is dielectrically heated, not only the surface layer and the back surface layer of the chemically strengthened glass plate 110 but also the intermediate layer can be heated. Therefore, the stress of the chemically strengthened glass plate 110 changes from the state shown in FIG. 5 described later to the state shown in FIG. 6 and FIG. 7 described later.

  FIG. 5 is an explanatory diagram of the stress distribution in the cross section of the chemically strengthened glass plate 110 before dielectric heating. In FIG. 5, the direction of the arrow indicates the direction in which the stress is applied, and the length of the arrow indicates the magnitude of the stress.

  Similarly to the glass plate 10 described above, the chemically strengthened glass plate 110 has a surface layer 121 and a back surface layer 122 in which compressive stress remains, and a tensile stress remains between the surface layer 121 and the back surface layer 122. An intermediate layer 123 is formed. The maximum residual compressive stress and thickness of the front surface layer 121 and the back surface layer 122, the average residual tensile stress of the intermediate layer 123, and the thickness of the chemically strengthened glass plate 110 are substantially the same as those of the glass plate 10 described above.

  FIG. 6 is a cross-sectional view taken along line AA in FIG. 4 and includes a predetermined region 130. 7 is a cross-sectional view taken along line B-B in FIG. 4, and is a rear cross section from the cross section shown in FIG. 6. Here, “rearward” means rearward in the movement direction of the predetermined region 130. 6 and 7, the direction of the arrow indicates the direction of the applied stress, and the length of the arrow indicates the magnitude of the stress.

  As shown in FIG. 6, the intermediate layer 123 in the predetermined region 130 has a temperature higher than that of the periphery due to dielectric heating, and therefore a tensile stress or a compressive stress smaller than the residual tensile stress shown in FIG. 5 is generated. Therefore, the extension of the crack 140 is hindered. In order to reliably prevent the extension of the crack 140, it is preferable that a compressive stress is generated as shown in FIG.

  Further, as shown in FIG. 6, the surface layer 121 and the back surface layer 122 in the predetermined region 130 have a temperature higher than that of the surroundings due to dielectric heating, so that a compressive stress larger than the residual compressive stress shown in FIG. Yes. Therefore, the extension of the crack 140 is hindered.

  In order to balance with the stress shown in FIG. 6, a tensile stress is generated in the intermediate layer 123 in the cross section behind the cross section shown in FIG. 6, as shown in FIG. 7. This tensile stress is larger than the residual tensile stress shown in FIG. 5, and a crack 140 is formed at a portion where the tensile stress reaches a predetermined value. The crack 140 penetrates the chemically strengthened glass plate 110 from the front surface 111 to the back surface 112, and the cutting in this embodiment is a so-called full cut cutting.

  In the state shown in FIGS. 6 and 7, when the predetermined region 130 is moved along the planned cutting line 113 on the surface 111 of the chemically strengthened glass plate 110, the crack 140 extends so as to follow the predetermined region 130. The tip of the crack 140 does not pass the predetermined area 130.

  Note that the tip of the crack 140 may move so as to overlap the predetermined area 130 instead of following the predetermined area 130. The closer the tip of the crack 140 is to the predetermined region 130, the better the cutting accuracy.

  Thus, in this embodiment, since the residual tensile stress of the intermediate layer 123 in the predetermined region 130 is relaxed by the thermal stress, it is possible to prevent the crack 140 from extending beyond the predetermined region 130. In the present embodiment, since a tensile stress larger than the residual tensile stress is generated in the vicinity of the rear of the predetermined region 130, it is possible to prevent the crack 140 from deviating from the locus of the predetermined region 130. Therefore, the cutting accuracy can be improved, and the glass plate 10 (see FIG. 1) having a desired size and shape can be obtained.

  The movement of the predetermined region 130 is performed by the relative movement of the first and second electrodes 131 and 132 with respect to the chemically strengthened glass plate 110. The movement of the predetermined region 130 is realized by the movement of the chemically strengthened glass plate 110 or the movement of the first and second electrodes 131 and 132, and may be realized by a combination thereof.

  By the way, according to the knowledge of the present inventor, if the average residual tensile stress of the intermediate layer 123 is 30 MPa or more, only the residual tensile stress of the intermediate layer 123 allows the cracks formed in the intermediate layer 123 to naturally expand (automatically). Run).

  The average residual tensile stress of the intermediate layer 123 is preferably 15 MPa or more so that the tensile stress used for cutting is dominated by the residual tensile stress of the intermediate layer 123 rather than the tensile stress generated by dielectric heating. Accordingly, the distance between the position where the tensile stress reaches a predetermined value, that is, the position of the tip end of the crack 140 and the predetermined region 130 is sufficiently shortened, so that good cutting accuracy can be obtained.

  The average residual tensile stress of the intermediate layer 123 is more preferably 30 MPa or more, and further preferably 40 MPa or more. When the average residual tensile stress is 30 MPa or more, the tensile stress used for cutting is only the residual tensile stress of the intermediate layer 123, and better cutting accuracy can be obtained.

  As shown in FIG. 8, the glass plate manufacturing method may include a step of spraying a coolant from the nozzle 150 onto the surface 111 of the chemically strengthened glass plate 110. As the refrigerant, a gas such as cooling air or a liquid such as cold water is used. A combination of gas and liquid may be used.

  The area 160 where the coolant is blown is disposed on the surface 111 in the vicinity of the rear of the predetermined area 130 so as to follow the predetermined area 130. As a result, a high temperature gradient and a high pressure gradient are generated in the vicinity of the rear of the predetermined region 130, so that the distance between the position where the tensile stress reaches a predetermined value, that is, the tip position of the crack 140 and the predetermined region 130. Becomes shorter. Therefore, the position controllability of the crack 140 is improved.

  In the present embodiment, the first and second electrodes 131 and 132 are used to form an alternating electric field. However, the chemically strengthened glass plate 110 itself may be used instead of the second electrode 132. good. In this case, the chemically strengthened glass plate 110 and the first electrode 131 are electrically connected via the circuit 133. In this case, it is desirable that the chemically strengthened glass plate 110 is grounded.

[Third Embodiment]
3rd Embodiment is related with the method of manufacturing said glass plate 10, and is related with the method of cut | disconnecting a chemically strengthened glass plate especially.

  FIG. 9 is an explanatory diagram of the glass plate manufacturing method according to the third embodiment of the present invention.

  The manufacturing method of a glass plate has the process of heating the predetermined area | region 230 at the temperature below an annealing point by irradiating the laser beam 232 to the predetermined area | region 230 of the chemically strengthened glass plate 210. FIG. The reason why the heating temperature is set to a temperature equal to or lower than the annealing point is that when the glass is heated to a temperature exceeding the annealing point, the glass flows in a viscous manner so as to relieve the thermal stress.

  In this step, the chemically strengthened glass plate 210 is cut by moving the predetermined region 230 along the planned cutting line 213 on the surface 211 of the chemically strengthened glass plate 210.

  The planned cutting line 213 is a virtual line scheduled to be a cutting point, and is configured in the same manner as in the third embodiment. A scribe line (groove line) may not be formed in advance on the entire cutting line 213. An initial crack serving as a starting point for cutting may be formed in advance at and near the starting end of the planned cutting line 213.

  The light source of the laser beam 232 is not particularly limited. For example, a UV laser (wavelength: 355 nm), a grain laser (wavelength: 532 nm), a semiconductor laser (wavelengths: 808 nm, 940 nm, 975 nm), a fiber laser (wavelength: 1060 to 100 nm). 1100 nm), YAG laser (wavelengths: 1064 nm, 2080 nm, 2940 nm) and the like. There is no limitation on the oscillation method of the light source, and either a CW laser that continuously oscillates laser light or a pulse laser that intermittently oscillates laser light can be used. The intensity distribution of the laser beam 232 is not limited, and may be a Gaussian type or a top hat type.

  The laser beam 232 emitted from the light source is collected by a condenser lens or the like, and is irradiated on the surface 211 of the chemically strengthened glass plate 210.

  The condensing position of the laser beam 232 may be on the light source side of the laser beam 232 or on the back surface 212 side with respect to the front surface 211. Further, the condensing position of the laser beam 232 may be outside or inside the chemically strengthened glass plate 210.

  The optical axis of the laser beam 232 may be orthogonal to the surface 211 on the surface 211 as shown in FIG. 9, for example, or may cross the surface 211 obliquely.

In the present embodiment, the chemically strengthened glass plate 210 and the laser beam 232 have an absorption coefficient of α (cm ⁻¹ ) for the chemically strengthened glass plate 210 with respect to the laser beam 232, and the thickness of the chemically strengthened glass plate 210 is t (cm ) Satisfies the expression of 0 <α × t ≦ 3.0.

Assuming that the intensity of the laser beam 232 before entering the chemically strengthened glass plate 210 is I ₀ and the intensity of the laser beam 232 when moving through the chemically strengthened glass plate 210 by a distance w (cm) is I, I = I The expression ₀ × exp (−α × w) is established.

  By making α × t greater than 0 and 3.0 or less, the intensity of the laser beam 232 in the chemically strengthened glass plate 210 is sufficiently high, and the laser beam 232 is not only the surface layer of the chemically strengthened glass plate 210. The intermediate layer and the back layer can be sufficiently heated. As a result, the stress generated in the chemically strengthened glass plate 210 changes from the state shown in FIG. 10 described later to the state shown in FIG. 11 and FIG.

  FIG. 10 is an explanatory diagram of the stress distribution in the cross section of the chemically strengthened glass plate 210 before laser heating. In FIG. 10, the direction of the arrow indicates the direction in which the stress is applied, and the length of the arrow indicates the magnitude of the stress.

  As shown in FIG. 10, the chemically strengthened glass plate 210 before laser heating has a front surface layer 221 and a back surface layer 222 in which compressive stress remains, similar to the above glass plate 10, and the front surface layer 221 and the back surface layer 222. An intermediate layer 223 in which a tensile stress remains is formed between the two. The maximum residual compressive stress and thickness of the surface layer 221 and the back layer 222, the average residual tensile stress of the intermediate layer 223, and the thickness of the chemically strengthened glass plate 210 are substantially the same as those of the glass plate 10 described above.

  FIG. 11 is a cross-sectional view taken along line AA in FIG. 9 and includes a predetermined region 230. 12 is a cross-sectional view taken along line BB in FIG. 9 and is a rear cross section from the cross section shown in FIG. Here, “rearward” means rearward in the movement direction of the predetermined region 230. In FIGS. 11 and 12, the direction of the arrow indicates the direction of the stress, and the length of the arrow indicates the magnitude of the stress.

  As shown in FIG. 11, in the intermediate layer 223 in the predetermined region 230, the laser beam 232 causes the temperature to be higher than the surrounding area, so that a tensile stress or a compressive stress smaller than the residual tensile stress shown in FIG. 10 is generated. Therefore, the extension of the crack 240 is hindered. In order to reliably prevent the crack 240 from extending, it is preferable that compressive stress is generated as shown in FIG.

  Further, as shown in FIG. 11, the surface layer 221 and the back surface layer 222 in the predetermined region 230 become higher in temperature than the surroundings due to laser heating, so that a compressive stress larger than the residual compressive stress shown in FIG. 10 is generated. Yes. Therefore, the extension of the crack 240 is hindered.

  In order to balance with the stress shown in FIG. 11, a tensile stress is generated in the intermediate layer 223 in the cross section behind the cross section shown in FIG. 11, as shown in FIG. 12. This tensile stress is larger than the residual tensile stress shown in FIG. 10, and a crack 240 is formed in a portion where the tensile stress reaches a predetermined value. The crack 240 penetrates the chemically strengthened glass plate 210 from the front surface 211 to the back surface 212, and the cutting in this embodiment is a so-called full cut cutting.

  In the state shown in FIGS. 11 and 12, when the predetermined region 230 is moved along the planned cutting line 213 on the surface 211 of the chemically strengthened glass plate 210, the crack 240 extends so as to follow the predetermined region 230. The tip of the crack 240 does not pass the predetermined area 230.

  Note that the tip of the crack 240 may move so as to overlap the predetermined region 230 instead of following the predetermined region 230. The closer the tip of the crack 240 is to the predetermined region 230, the better the cutting accuracy.

  Thus, in this embodiment, since the residual tensile stress of the intermediate layer 223 in the predetermined region 230 is relaxed by the thermal stress, the crack 240 can be prevented from extending beyond the predetermined region 230. In the present embodiment, since a tensile stress larger than the residual tensile stress is generated in the vicinity of the rear of the predetermined region 230, it is possible to prevent the crack 240 from deviating from the locus of the predetermined region 230. Therefore, the cutting accuracy can be improved, and the glass plate 10 (see FIG. 1) having a desired size and shape can be obtained.

  The movement of the predetermined region 230 is performed by the relative movement of the laser beam 232 with respect to the chemically strengthened glass plate 210. The movement of the predetermined region 230 is realized by movement of the chemically strengthened glass plate 210, movement of the light source of the laser light 232, or rotation of a mirror provided in the optical path of the laser light 232, and may be realized by a combination of these. .

  By the way, according to the knowledge of the present inventor, when the average residual tensile stress of the intermediate layer 223 is 30 MPa or more, only the residual tensile stress of the intermediate layer 223 allows the cracks formed in the intermediate layer 223 to expand naturally (self Run).

  The average residual tensile stress of the intermediate layer 223 is preferably 15 MPa or more so that the tensile stress used for cutting is dominated by the residual tensile stress of the intermediate layer 223 rather than the tensile stress generated by dielectric heating. Accordingly, the distance between the position where the tensile stress reaches a predetermined value, that is, the position of the tip end of the crack 240 and the predetermined region 230 is sufficiently shortened, so that a good cutting accuracy can be obtained.

  The average residual tensile stress of the intermediate layer 223 is more preferably 30 MPa or more, and further preferably 40 MPa or more. When the average residual tensile stress is 30 MPa or more, the tensile stress used for cutting is only the residual tensile stress of the intermediate layer 223, and better cutting accuracy can be obtained.

  Since high transparency is required for glass depending on the application, α × t is preferably closer to 0 when the laser wavelength used is close to the wavelength region of visible light. However, since α × t is too small, the absorption efficiency is deteriorated. Therefore, it is preferably 0.0005 or more (laser light absorption rate 0.05% or more), more preferably 0.002 or more (laser light absorption rate 0.2 % Or more), more preferably 0.004 or more (laser light absorption rate 0.4% or more).

  Glass, on the other hand, requires low transparency, so that when the used laser wavelength is close to the wavelength region of visible light, the larger α × t is better. However, if α × t is too large, surface absorption increases, and crack extension cannot be controlled. Therefore, α × t is preferably 3.0 or less (laser light absorptivity 95% or less), more preferably 0.1 or less (laser light absorptivity 10% or less), and further preferably 0.02 or less (laser Light absorption rate is 2% or less).

The absorption coefficient α is determined by the wavelength of the laser beam 232, the glass composition of the chemically strengthened glass plate 210, and the like. For example, the content of iron oxide (including FeO, Fe ₂ O ₃ and Fe ₃ O ₄ ) and the content of cobalt oxide (including CoO, Co ₂ O ₃ and Co ₃ O ₄ ) in the chemically strengthened glass plate 210 As the content of copper oxide (including CuO and Cu ₂ O) increases, the absorption coefficient α in the near-infrared wavelength region near 1000 nm increases. Furthermore, the absorption coefficient α increases in the vicinity of the absorption wavelength of the rare earth atom as the content of the oxide of the rare earth element (for example, Yb) in the chemically strengthened glass plate 210 increases.

  The content of iron oxide in the chemically strengthened glass plate 210 depends on the type of glass constituting the chemically strengthened glass plate 210, but in the case of soda lime glass, for example, is 0.02 to 1.0% by mass. By adjusting the content of iron oxide in this range, α × t in the near infrared wavelength region near 1000 nm can be adjusted to a desired range. Instead of adjusting the content of iron oxide, the content of cobalt oxide, copper oxide, or rare earth element oxide may be adjusted.

The absorption coefficient α in the near-infrared wavelength region near 1000 nm is set according to the application. For example, in the case of an automotive window glass, 3 cm ⁻¹ or less, in the case of an architectural window glass, 0.6 cm ⁻¹ or less, for display In the case of glass, it is preferably 0.2 cm ⁻¹ or less.

  The wavelength of the laser beam 232 is preferably 250 to 3000 nm. By setting the wavelength of the laser beam 232 to 250 to 3000 nm, both the transmittance of the laser beam 232 and the heating efficiency by the laser beam 232 can be achieved. The wavelength of the laser beam 232 is more preferably 300 to 2000 nm, and still more preferably 800 to 1500 nm.

  The predetermined region 230 may be formed in a circular shape having a diameter Φ on the surface (laser beam incident surface) 211. In this case, the diameter Φ is determined in consideration of cutting accuracy and laser power. As the diameter Φ decreases, the cutting accuracy near the start and end of the planned cutting line 213 increases. On the other hand, the power density of the laser beam increases, and the cut surface becomes rough and fine cracks are formed. is there. For example, the diameter Φ is set to be larger than 0.18 mm and smaller than 1.03 mm. In order to increase the cutting accuracy over the entire cutting line 213, the diameter Φ is preferably 0.5 mm or less.

  The predetermined region 230 may be formed in a rectangular shape, an elliptical shape, or the like on the surface 211, and the shape thereof is not limited.

  As shown in FIG. 13, the glass plate manufacturing method may include a step of spraying a coolant from the nozzle 250 onto the surface 211 of the chemically strengthened glass plate 210. As the refrigerant, a gas such as cooling air or a liquid such as cold water is used. A combination of gas and liquid may be used.

  The area 260 where the refrigerant is blown is arranged in the vicinity of the rear of the predetermined area 230 on the surface 211 and follows the predetermined area 230. As a result, a high temperature gradient is generated in the vicinity of the rear of the predetermined region 230, and a high pressure gradient is generated. Therefore, the distance between the position where the tensile stress reaches a predetermined value, that is, the tip position of the crack 240 and the predetermined region 230. Becomes shorter. Therefore, the position controllability of the crack 240 is improved.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Example 1]
(Production of chemically strengthened glass plate)
As the glass for chemical strengthening, a flat glass having a length of 100 mm × width of 120 mm × thickness of 0.7 mm was prepared. The flat glass is expressed by mass%, SiO ₂ : 64.5%, Al ₂ O ₃ : 6.0%, MgO: 11.0%, Na ₂ O: 12.0%, K ₂ O: 4%, ZrO ₂ : contained 2.5%.

The chemically strengthened glass plate was prepared by immersing the prepared flat glass in KNO ₃ molten salt, performing an ion exchange treatment, and then cooling to near room temperature. The temperature of the KNO ₃ molten salt was 400 ° C., and the immersion time was 2.5 hours.

  The maximum residual compressive stress and thickness of the chemically strengthened surface layer and the maximum residual compressive stress and thickness of the chemically strengthened back layer were measured by a surface stress meter (FSM-6000LE, manufactured by Orihara Seisakusho). Moreover, the average residual tensile stress of the intermediate layer was calculated by substituting the measurement result of the surface stress meter into the above formula (1).

  As a result of the measurement, the chemically strengthened surface layer and the back surface layer had the same maximum residual compressive stress (788 MPa) and the same thickness (25 μm). The average residual tensile stress of the intermediate layer was 30 MPa.

(Cut the chemically strengthened glass plate)
The chemically tempered glass plate was cut by the cutting method shown in FIG.

  The planned cutting line on the surface of the chemically strengthened glass plate was composed of one linear portion. The straight portion was parallel to one side of the outer periphery of the surface, and the distance between the one side was 10 mm.

  Prior to the cutting, a scribe line covering the entire planned cutting line was not formed, and an initial crack serving as a base point for cutting was formed by a file at the starting end of the planned cutting line and in the vicinity thereof.

  In order to apply an alternating electric field to a predetermined region of the chemically strengthened glass plate, the power applied to the first electrode was 20 W, and the frequency was 15 MHz. The predetermined area was moved at a speed of 40 mm / sec from the start end to the end of the planned cutting line.

(Evaluation of glass plate after cutting)
As a result of cutting, a glass plate having a desired size and shape (length 100 mm × width 60 mm × thickness 0.7 mm) could be obtained. The boundary line between the side end surface, which is a cut surface, and the surface has the same size and shape as the planned cutting line, and has only a linear portion. The following evaluation was performed about the obtained glass plate.

  The maximum residual compressive stress and thickness of the surface layer after cutting, and the maximum residual compressive stress and thickness of the back layer after cutting were measured by the above methods. Moreover, the average residual tensile stress of the intermediate layer was calculated based on the above formula (1).

  The linearity of the boundary line between the side end surface that is a cut surface and the surface is as follows: (1) Maximum distance (μm) between a point on the boundary line and a virtual straight line connecting both ends of the boundary line; (2) Maximum distance d The ratio (d / L) between (mm) and the length L (mm) of the imaginary straight line was evaluated.

  The angle θ formed between the side end surface, which is a cut surface, and the surface was measured by enlarging a micrograph. The measurement was performed at predetermined intervals (10 mm) from one end of the boundary line, and the minimum value and the maximum value were obtained.

  The quality at the time of assembling to other members was evaluated based on the state of occurrence of perspective distortion and reflection distortion of the glass plate when fitted into the opening of the frame. In the visual inspection, a sample having no perspective distortion and a reflection distortion was designated as “A”, and one having a perspective distortion or a reflection distortion (difficult to visually recognize) was designated as “B”. The frame was made of ABS resin, and the opening of the frame was substantially rectangular (length 100 mm, width 60 mm).

  The evaluation results are shown in Table 1. Since the surface layer and the back surface layer showed the same maximum residual compressive stress and the same thickness, Table 1 shows only the data of the surface layer.

[Example 2]
The production of the chemically strengthened glass plate was performed in the same manner as in Example 1.

  The chemically tempered glass plate was cut in the same manner as in Example 1 except that the cutting method shown in FIG. 9 was used instead of the cutting method shown in FIG.

A fiber laser (wavelength band: 1075 to 1095 nm) was used as a light source of laser light irradiated to a predetermined region of the chemically strengthened glass plate. The absorption coefficient α of the chemically strengthened glass plate with respect to laser light is 0.48 cm ^{−1 as} measured by an ultraviolet-visible near-infrared spectrophotometer Lambda 950, and the product α with the thickness t (cm) of the chemically strengthened glass plate. Xt was 0.0672.

  The predetermined region was formed in a circular shape with a diameter of 0.3 mm on the surface of the chemically strengthened glass plate, and was moved at a speed of 10 mm / sec from the start end (initial crack) to the end of the planned cutting line.

  As a result of cutting, a glass plate having a desired size and shape could be obtained. The boundary line between the side end surface, which is a cut surface, and the surface has the same size and shape as the planned cutting line, and has only a linear portion.

  The evaluation results of the obtained glass plate are shown in Table 1. Since the surface layer and the back surface layer showed the same maximum residual compressive stress and the same thickness, Table 1 shows only the data of the surface layer.

[Example 3]
The production of the chemically strengthened glass plate was performed in the same manner as in Example 1.

  The chemically tempered glass plate was cut in the same manner as in Example 2 except that a carbon dioxide laser (wavelength: 10600 nm) was used instead of a fiber laser (wavelength band: 1075 to 1095 nm) as a laser light source.

The absorption coefficient α of the chemically strengthened glass plate with respect to the laser light is measured in advance with an ultraviolet-visible-near-infrared spectrophotometer Lambda 950 and exceeds 1000 cm ⁻¹ , which is a product of the thickness t (cm) of the chemically strengthened glass plate. α × t exceeded 50.

  The predetermined area is formed in an elliptical shape (length 12 mm, width 3 mm) in the moving direction on the surface of the chemically strengthened glass plate, and moves at a speed of 10 mm / sec from the start end (initial crack) to the end of the planned cutting line. I let you. The long oval shape in the moving direction is to heat the same place for a long time, to suppress the surface from being overheated momentarily and to promote the heat transfer from the surface to the inside, thereby heating the inside. It is.

  As a result of cutting, a glass plate having a desired size and shape could be obtained. The boundary line between the side end surface, which is a cut surface, and the surface has the same size and shape as the planned cutting line, and has only a linear portion.

  The evaluation results of the obtained glass plate are shown in Table 1. Since the surface layer and the back surface layer showed the same maximum residual compressive stress and the same thickness, Table 1 shows only the data of the surface layer.

表１に示すように、例１、例２のガラス板は、ｄ／Ｌが２．０×１０^−３以下であるので、枠体の開口部への嵌め込み時に、他部材に対して精度良く組み付けることができた。例１〜例２のガラス板は、最大距離が２００μｍ以下であるので、枠体の開口部への嵌め込み時に、他部材に対して精度良く組み付けることができた。例１〜例２のガラス板は、なす角θが８２〜９８の範囲内であるので、他部材に対して精度良く組み付けることができた。

As shown in Table 1, since the glass plates of Examples 1 and 2 have a d / L of 2.0 × 10 ⁻³ or less, when fitted into the opening of the frame body, the glass plates of the glass plate of Example 1 and Example 2 are accurate with respect to other members. I was able to assemble it. Since the maximum distance of the glass plates of Examples 1 and 2 was 200 μm or less, the glass plates could be assembled to other members with high accuracy when fitted into the opening of the frame. Since the glass plates of Examples 1 to 2 have an angle θ formed in the range of 82 to 98, they could be assembled with high accuracy to other members.

DESCRIPTION OF SYMBOLS 10 Glass plate 11 Front surface 12 Back surface 13 Side end surface 21 Front surface layer 22 Back surface layer 23 Intermediate layer 31 Area where compressive stress remains 32 Area where compressive stress remains 33 Area where tensile stress remains 40 Boundary line 41 Linear portion 51 Virtual straight line DESCRIPTION OF SYMBOLS 110 Chemically strengthened glass plate 111 Surface 113 Planned cutting line 130 Predetermined area | region 210 Chemically strengthened glass plate 211 Surface 213 Cutting planned line 230 Predetermined area | region 232 Laser beam

Claims (6)

It is a cut surface having a surface layer and a back surface layer that are cut after chemical strengthening and in which compressive stress remains, and an intermediate layer that is formed between the surface layer and the back surface layer and in which tensile stress remains. In the glass plate having a region where compressive stress remains and a region where tensile stress remains on the side end face,
The boundary line between the side end face that is the cut surface and the surface includes a linear portion,
The linear portion has a maximum distance between a point on the linear portion and a virtual straight line connecting both ends of the linear portion as d (mm), and the length of the virtual straight line is L (mm). Then, the glass plate characterized by satisfying an expression of d / L ≦ 2.0 × 10 ⁻³ .   The glass plate according to claim 1, wherein the maximum distance is 200 μm or less.   3. The glass plate according to claim 1, wherein an angle formed by a side end surface that is the cut surface and the surface is 82 to 98 ° at an arbitrary point on the linear portion. The surface is formed in a rectangular shape,
The said linear part is a glass plate of any one of Claims 1-3 which comprises one side of the outer periphery of the said surface. It is a method of manufacturing the glass plate of any one of Claims 1-4,
By applying an alternating electric field to a predetermined region of the chemically strengthened glass plate, and subjecting the predetermined region to dielectric heating at a temperature below the annealing point,
The manufacturing method of the glass plate which cut | disconnects the said chemically strengthened glass plate in this process by moving the said predetermined area | region along the cutting projected line on the surface of the said chemically strengthened glass plate. It is a method of manufacturing the glass plate of any one of Claims 1-4,
Irradiating the predetermined region of the chemically strengthened glass plate with a laser beam to heat the predetermined region at a temperature below the annealing point;
In this step, by moving the predetermined region along the planned cutting line on the surface of the chemically strengthened glass plate, the chemically strengthened glass plate is cut,
The chemical tempered glass plate and the laser beam have an absorption coefficient of α (cm ⁻¹ ) for the laser beam and α (cm ⁻¹ ), and the thickness of the chemically tempered glass plate is t (cm). A method for producing a glass plate satisfying the formula of α × t ≦ 3.

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