KR101346930B1 - Glass plate and method for manufacturing glass plate - Google Patents

Abstract

When the glass plate is produced by the downdraw method, the glass surface is strengthened to such an extent that the glass surface is hardly scratched without adversely affecting the efficiency of the processing after the glass molding. The glass plate has a tensile stress layer formed inside the glass plate, and a compressive stress layer formed on both sides of the tensile stress layer. The compressive stress layer is formed at a depth of greater than 10 μm in the thickness direction of the glass plate and 50 μm or less from the surface of the glass plate, and the thickness of the compressive stress layer is less than one-third of the thickness of the glass plate. The absolute value of the stress value of the said compressive stress layer is 4 Mpa or less, and the absolute value of the stress value of the said tensile stress layer is 0.4 Mpa or less.

Description

Glass plate and manufacturing method of glass plate {GLASS PLATE AND METHOD FOR MANUFACTURING GLASS PLATE}

The present invention relates to a glass plate and a method for producing the glass plate.

In flat panel displays (henceforth "FPD"), such as a liquid crystal display and a plasma display, a thin glass plate whose thickness is 1.0 mm or less is used as a glass substrate. In recent years, the enlargement of the FPD glass substrate advances, for example, the glass plate called the 8th generation of size 2200 mm x 2500 mm is used.

In order to manufacture such an FPD glass substrate, the down-draw method is most used. In the down-draw method, a strip-shaped glass ribbon is continuously formed by overflowing a molten glass from the groove | channel of a shaping | molding apparatus. At that time, the glass ribbon is pulled down with a roller or the like. At this time, thickness adjustment of a glass ribbon is performed according to the speed | rate which pulls down a glass ribbon. Thereafter, the glass ribbon is cut into predetermined lengths to produce a glass plate.

For example, Patent Document 1 (Japanese Patent Application Publication No. 2009-519884) discloses a glass plate manufacturing apparatus as shown in FIG. 11. This glass plate manufacturing apparatus is equipped with the heat insulation structure 8 which surrounds the shaping | molding apparatus 7 and the shaping | molding apparatus 7. As shown in FIG. The heat insulation structure 8 is for maintaining the temperature of the molten glass which overflows from the shaping | molding apparatus 7 by maintaining the high temperature air around the shaping | molding apparatus 7, and is normally the gate 81 which passes a glass ribbon. Other than that, it becomes a sealed structure.

Specifically, in the glass plate manufacturing apparatus disclosed in Patent Document 1, the heat insulating structure 8 is composed of a container-shaped main body 8A which is opened downward, and a gate structure 8B arranged to block the opening of the main body 8A. have. The interior of the gate structure 8B is a cavity, and cooling air is supplied to the interior of the gate structure 8B through the cooling tube 82. Thereby, in the glass plate manufacturing apparatus disclosed by patent document 1, it is possible to cool the glass ribbon 9 immediately after formation.

Under such a situation, for example, a glass substrate for a display that can be made thinner and lighter, has high mechanical strength and transparency, and can be manufactured in a short time is known (Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-174810) ). The glass substrate is SiO ₂ 40 to 70 wt%, Al ₂ O ₃ from 0.1 to 20 wt%, Na the ₂ O 0 to 20% by weight, Li the ₂ O 0 to 15 wt%, ZrO ₂ 0.1 to 9 and containing% by weight, the total content of Li ₂ O and Na ₂ O is formed of a glass material of 3 to 20% by weight. The compressive stress layer of 50 micrometers or more in depth is formed in the surface of this glass substrate by a chemical strengthening process.

In addition, there is known a glass having an ion exchange surface layer having a depth of at least 20 μm from the surface by quenching from a first temperature higher than the annealing point to a second temperature lower than the strain point and performing chemical strengthening by ion exchange (patent document). 3 (US 2009/0220761 A1)).

Moreover, the manufacturing method of the tempered glass which can optimize the compressive stress value and thickness of the compressive stress layer in glass so that high mechanical strength can be obtained, and also can heat-process easily is known (patent document 4 (Japanese patent) Application Publication No. 2010-168252).

In this manufacturing method, after cooling the temperature range from a slow cooling point to a strain point at the cooling rate of 200 degrees C / min or less, Preferably it is 50 degrees C / min or less, and a chemical strengthening process is performed.

Patent Document 1: Japanese Patent Application Publication No. 2009-519884 Patent Document 2: Japanese Patent Application Laid-Open No. 2002-174810 Patent Document 3: US 2009/0220761 A1 Patent Document 4: Japanese Patent Application Laid-open No. 2010-168252

By the way, a volatile component volatilizes in the interface which contact | connects air from molten glass. The inventors of the present invention thought that if the volatilization was effectively used in the downdraw method, a desired compressive stress layer could be formed on both sides of the glass plate.

(First issue)

However, when the heat insulation structure 8 is a closed structure like the manufacturing apparatus disclosed in patent document 1, since the volatilization of the volatile component from the molten glass which overflows from a shaping | molding apparatus is suppressed, a compressive stress layer with a high stress value can be formed. none.

In addition, Patent Document 1 provides, in the gate structure 8B, a jet port 83 that blows out the cooling air for cooling from the cooling tube 82 in the space covered by the main body 8A, and provides a gate from the jet port 83. It is also disclosed to cool the glass ribbon 9 by flowing cooling air into the 81. However, even if forced convection occurs in the vicinity of the gate 81 in this manner, since the air above, that is, most of the air in the space covered by the main body 8A, stays there, the volatile component from the molten glass. Volatilization of is suppressed.

(Second issue)

In the glass substrate disclosed by patent document 2, a compressive stress layer is formed in the surface of a glass plate by performing ion exchange and chemical strengthening process. However, chemically strengthening the glass substrate using alkali ions used for ion exchange affects the TFT (Thin Film Transistor) characteristics formed on the glass substrate, for example, and also contaminates the liquid crystal material. It is not preferable at this point. For this reason, the chemically strengthened glass by ion exchange is hard to use for a liquid crystal display glass substrate. Even if chemical strengthening treatment by ion exchange is possible, scratches on the surface of the glass plate in the previous step of the chemical strengthening treatment cannot be avoided. On the other hand, when the said chemical strengthening process is performed immediately after shaping | molding of a glass plate, the efficiency of the processing process including cutting of the glass surface and grinding, polishing, and shape processing of a glass plate after that fall will fall.

Since the glass plate disclosed by patent document 3 quenchs glass in a slow cooling process, a small compressive stress layer may arise in the glass surface. However, since the stress value of the compressive stress layer obtained by quenching the glass only in the slow cooling step is extremely low, the surface of the glass may be scratched in the previous step of the chemical strengthening treatment. Moreover, in the thin glass plate, the stress value of the tensile stress layer formed inside the glass plate is large due to the internal stress distribution showing a parabolic shape along the thickness direction. The large stress value of the tensile stress layer is, for example, when cutting a glass plate, that a scribe line of a predetermined depth inserted for cutting may extend out of the thickness direction of the glass plate and it becomes difficult to divide the glass plate into desired dimensions. It is not preferable in that point.

In Patent Document 4, the stress value of the compressive stress layer is increased by slowly cooling the glass and chemically strengthening the molded glass plate. However, the glass plate is cut to a predetermined size and shaped after being molded and before being chemically strengthened. A glass plate may be damaged on the surface during conveyance between these processes, and cutting and shape processing. If the glass plate breaks on the glass surface before chemically strengthening, for example, even after chemically strengthening to obtain high strength, scratches remain on the glass surface.

In view of these circumstances, the present invention provides a glass plate manufacturing apparatus capable of promoting volatilization of volatile components from the molten glass overflowing from the molding apparatus, and a glass plate manufacturing method using the glass plate manufacturing apparatus, and the glass plate manufacturing method described above. It is a 1st object to provide the glass plate obtained by this.

In addition, the present invention provides a glass plate and a method for producing a glass plate whose glass surface is hardened to the extent that the glass surface is hardly scratched without adversely affecting the efficiency of the processing after glass molding during the production of the glass plate. do.

(1st invention)

In order to achieve the first object, one embodiment of the present invention is an apparatus for producing a glass plate by a down-draw method, overflows the molten glass from both sides of the groove, and induces the overflowed molten glass from the wall surface to fuse And a heat insulated structure having a forming apparatus for forming a glass ribbon by forming a glass ribbon, and a gate which surrounds the forming apparatus and allows the glass ribbon formed by the forming apparatus to pass therethrough, wherein the heat insulated structure includes the heat insulated structure from outside the heat insulated structure. Provided is a glass plate manufacturing apparatus provided with a discharge port which is introduced inside and discharges gas that has risen along the molten glass flowing down on the wall surface of the molding apparatus to the outside of the heat insulating structure.

In addition, one embodiment of the present invention is a method of manufacturing a glass plate by a downdraw method, wherein the molten glass is overflowed from both sides of a groove of a molding apparatus enclosed by a heat insulating structure, and introduced into the heat insulating structure from the outside of the heat insulating structure. Provided is a glass plate manufacturing method comprising the step of raising the gas along the molten glass flowing down the wall surface of the molding apparatus and then discharged out of the heat insulating structure.

Moreover, one form of this invention is a glass plate obtained by the said glass plate manufacturing method, and provides the glass plate which has a compressive stress layer in both front and back.

(2nd invention)

In order to achieve the second object, one embodiment of the present invention provides a glass plate molded by a downdraw method.

A Si high concentration region in which the ratio of the atomic concentration (atomic%) of Si to the atomic concentration (atomic%) of Si at the central position in the thickness direction of the glass plate is 5% or more is greater than zero along the thickness direction from the glass surface. It is formed in a range of depth that is larger than 30 nm.

The Si high concentration region has a maximum peak of Si atomic concentration, and the Si atomic concentration along the thickness direction of the glass plate decreases continuously from the maximum peak position to the surface and the center position of the glass plate.

Another embodiment of the present invention provides a glass plate molded by a downdraw method.

The glass plate has a tensile stress layer formed inside the glass plate and a compressive stress layer formed on both sides of the tensile stress layer.

The absolute value of the stress value of the compressive stress layer is 4 MPa or less, and the compressive stress layer is formed in a depth of greater than 10 μm in the thickness direction of the glass plate and 50 μm or less from the surface of the glass plate, and the thickness of the compressive stress layer is It is less than one-third of the thickness of the said glass plate.

The absolute value of the stress value of the said tensile stress layer is 0.4 Mpa or less, and the deviation of the stress value of the said tensile stress layer is 0.2 Mpa or less.

Another embodiment of the present invention provides a method for producing a glass plate. The above-

Melting the glass raw material,

Forming a glass ribbon from the molten glass using the downdraw method;

The process of cutting the said glass ribbon and forming a glass plate is provided.

In that case, the said glass ribbon has a Si high concentration area | region whose ratio of the atomic concentration (atomic%) of Si to the atomic concentration (atomic%) of Si in the center position of the thickness direction of the said glass plate is 5% or more, and a glass surface. Is formed in a depth range of greater than 0 and 30 nm or less along the thickness direction from the, wherein the Si high concentration region has a maximum peak of Si atomic concentration, and the Si atomic concentration along the thickness direction of the glass plate is determined from the maximum peak position of the glass plate. It is shaped to continuously decrease to the surface and the center position.

Another embodiment of the present invention provides a method for producing a glass plate. The above-

Melting the glass raw material,

Forming a glass ribbon from the molten glass using the downdraw method;

And a step of cutting the glass ribbon to form a glass plate.

In that case, it is a compressive stress layer formed in the range of the depth which is larger than 10 micrometers in the thickness direction of the said glass ribbon and is 50 micrometers or less from the surface of the said glass ribbon, and has thickness which is less than one-third of the thickness of the said glass ribbon, and a compressive stress The glass ribbon is molded so as to have two compressive stress layers having an absolute value of 4 MPa or less and a tensile stress layer having an absolute value of the tensile stress value of 0.4 MPa or less sandwiched between the two compressive stress layers.

According to the said 1st invention, volatilization of the volatile component from a molten glass can be promoted by raising the gas which passes through a heat insulation structure along the molten glass which flows down on the wall surface of a shaping | molding apparatus. Thereby, the glass plate in which the compressive stress layer with high stress value was formed in both front and back was obtained.

The glass plate of the said 2nd invention does not adversely affect the efficiency of the processing process after glass shaping | molding at the time of manufacture of a glass plate, and a glass surface is strengthened so that it is hard to be damaged to a glass surface. The glass manufacturing method of this invention can manufacture the said glass plate efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the internal stress distribution of the glass plate of this embodiment.
It is a figure which shows the internal stress distribution of the conventional glass plate obtained when quenching glass in a slow cooling process.
It is a figure explaining an example of the flow of the manufacturing method of the glass plate of this embodiment.
It is a figure explaining the shape processing in the manufacturing method of the glass plate of this embodiment.
It is sectional drawing of the glass plate manufacturing apparatus which manufactures the glass plate of this embodiment.
It is a perspective view of the glass plate manufacturing apparatus shown in FIG.
It is sectional drawing of the glass plate manufacturing apparatus of a modification.
It is sectional drawing of the glass plate manufacturing apparatus of another modified example.
It is a figure which shows distribution of internal stress which measured the glass plate of this embodiment.
FIG. 10: is a figure which shows distribution of Si atomic concentration (%) which measured the glass plate of this embodiment.
It is sectional drawing of the conventional glass manufacturing apparatus.

The glass plate of this invention and the manufacturing method of a glass plate are demonstrated below.

(Schematic explanation of the glass plate)

1: is sectional drawing which shows the internal stress distribution of the glass plate 10 of this embodiment.

The glass plate 10 is manufactured by the downdraw method, and is used for an FPD glass substrate, for example. The glass plate 10 is not particularly limited in thickness or size. The tempered glass which strengthened the glass plate 10 is used for the cover glass of the display screen of an electronic device, for example.

The glass plate 10 has the tensile stress layer 12 formed in the inside of a glass plate, and the compressive stress layer 14 formed in the both sides of the tensile stress layer 12, as shown in FIG.

The compressive stress layer 14 is formed from a surface of the glass plate 10 to a depth of greater than 10 μm in the thickness direction of the glass plate 10 and 50 μm or less, and the thickness of the compressive stress layer 14 is the thickness of the glass plate 10. Is less than 1/13. The absolute value of the stress value of the compressive stress layer 14 is 4 MPa or less, and the absolute value of the stress value of the tensile stress layer 12 is 0.4 MPa or less.

Specifically, when the thickness of the compressive stress layer 14 is W ₁ , the thickness W ₁ is larger than 0 μm and 50 μm or less, and less than 1/13 of the thickness W ₀ of the glass plate 10. The maximum value S ₁ of the stress value (absolute value) of the compressive stress layer 14 is 4 MPa or less, and the maximum value S ₂ of the stress value (absolute value) of the tensile stress layer 12 is 0.4 MPa or less. .

The thick solid line in FIG. 1 has shown the internal stress distribution along the thickness direction of the glass plate 10, ie, the compression and tensile stress profile. It is a figure which shows the internal stress distribution of the conventional glass plate obtained when quenching glass in a slow cooling process.

The compression and tensile stress profile obtained when the glass is quenched in a slow cooling process is a profile which draws a parabola. When the glass is quenched, the compressive stress layer formed on the glass plate is caused by the difference in thermal expansion between the glass surface and the inside. This difference in thermal expansion rate occurs due to the thermal conductivity of the glass. In addition, the compression stress layer thickness (W obtained from the prior art in the slow cooling step, ₁₎ (see Fig. 2), the thickness of the glass sheet (W "is at least one tenth of _0).

In contrast, in the glass plate 10, a thin compressive stress layer 14 is formed in the vicinity of the surface of the glass plate 10 due to the difference in thermal expansion due to the Si high concentration region formed on the glass surface. The Si high concentration region is formed by accelerating the volatilization of the volatile component or increasing the volatilization amount from the surface of the molten glass or the glass ribbon in the molding step of the glass ribbon as described later. At this time, the tensile stress layer 12 has a low stress value substantially constant in the thickness direction of the glass plate 10, and is different from the case where the tensile stress value of the conventional tensile stress layer is distributed like a parabola in the thickness direction of the glass plate. Do.

In addition, since the compression by the compressive stress layer 14 and the tension by the tensile stress layer 12 are canceled in the entire glass plate 10, when the compressive stress layer 14 becomes thin, the compressive stress layer ( The stress value (absolute value) of 14) becomes high. For this reason, the compressive stress layer 14 has a stress value larger than the stress value of the compressive stress layer obtained only when quenching glass in a slow cooling process, for example. That is, since the compressive stress layer 14 having a large stress value is formed on the glass surface of the glass plate 10, the glass surface of the glass plate 10 is less likely to be wound than the conventional glass plate which reinforced the glass surface only in the slow cooling process.

The glass plate 10 is demonstrated in detail below.

(Detailed explanation of the glass plate)

The thickness W ₁ of the compressive stress layer 14 formed on the glass plate 10 is larger than 0 μm and 50 μm or less. The compressive stress layer 14 is formed on the glass surface. That is, the compressive stress layer 14 is formed at a depth of up to 50 µm from the glass surface. In other words, the depth from the surface of the compressive stress layer 14 is 50 μm or less. Although the depth of the compressive stress layer can be deepened by promoting volatilization from the surface of the molten glass or the glass ribbon in the molding process, when the depth of the compressive stress layer 14 exceeds 50 µm, it is possible to achieve a suitable molding condition. It causes deviations or decreases in productivity. For this reason, the depth from the surface of the compressive stress layer 14 is 50 micrometers or less. For this reason, it is preferable that the depth of the compressive stress layer 14 is 45 micrometers or less, 40 micrometers or less, and 38 micrometers or less. Such a preferable form can be realized by adjusting the composition of the glass plate and the manufacturing conditions of the glass plate including the conditions which accelerate | stimulate volatilization of a volatile component from the surface of the glass ribbon during shaping | molding, or increase volatilization amount.

In addition, the depth of the compressive stress layer 14 in this specification shows the depth from the glass surface of the deepest part of the compressive stress layer formed in one surface of the front and back of the glass plate 10. That is, the compressive stress layer 14 which has the said depth is formed in the front and back surface of the glass plate 10, respectively.

In addition, the depth of the compressive stress layer 14 is more than 10 μm. By making the depth of the compressive stress layer 14 more than 10 micrometers, glass can be prevented from being easy to be broken by the fine scratches resulting from handling. The depth of the compressive stress layer 14 is more preferably 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, or 35 μm or more in consideration of the fact that the glass plate 10 is hardly damaged even if a deep wound occurs.

The depth of the compressive stress layer 14 formed on the glass surface is less than 1/13 of the thickness W ₀ of the glass plate 10, but less than 1/15, less than 1/17, less than 1/20, less than 1/22. It is preferable that it is less than 1/24.

Such a preferable form can also be realized by adjusting the manufacturing conditions of a glass plate and the composition of a glass plate containing the conditions which accelerate | stimulate the volatilization of a volatile component from the surface of the glass ribbon during shaping | molding, or increase the volatilization amount.

The maximum stress value (absolute value) of the compressive stress layer 14 formed in the surface vicinity of the glass plate 10 is 4 MPa even if it is maximum. When the maximum value of the said stress value (absolute value) exceeds 4 MPa, the sum total of the stress value of the compressive stress layer 14 will become large, and it becomes difficult to process the glass plate 10, for example, shape. For this reason, it is preferable that the maximum value of the stress value (absolute value) of the compressive stress layer 14 is 3.7 MPa or less, 3.5 MPa or less, 3.0 MPa or less, 2.8 MPa or less. Moreover, it is preferable that the maximum value of the stress value (absolute value) of the compressive stress layer 14 is 0.1 MPa or more, 0.5 MPa or more, 1 MPa or more, 1.5 MPa or more, and 2 MPa or more. Since the compressive stress layer 14 is a layer having a stress value (absolute value) of more than 0 MPa, the mechanical stress of the glass plate 10 is improved by forming the compressive stress layer 14 on the glass surface of the glass plate 10.

In addition, the "stress value" in this specification has shown the average value of 0-10 micrometers from the surface of the sample in the sample cut out for every predetermined depth from the glass surface of the glass plate 10. As shown in FIG. Therefore, the glass plate which the compressive stress layer 14 has the stress value exceeding the range of the said stress value locally is also included as the glass plate 10. FIG.

The stress value of the tensile stress layer 12 formed inside the glass plate 10 is substantially constant in the thickness direction of the glass plate 10 as described above. The stress value of this tensile stress layer 12 is 0.4 MPa or less as mentioned above. When the maximum value of the stress value (absolute value) of the tensile stress layer 12 exceeds 0.4 MPa, for example, when cutting a glass plate, a scribe line of a predetermined depth inserted for cutting extends outwardly in the thickness direction of the glass plate. It may become difficult to divide the glass plate 10 to a desired dimension. For this reason, it is preferable that the maximum value (absolute value) of the stress value of the tensile stress layer 12 is 0.3 MPa or less, 0.2 MPa or less, 0.15 MPa, 0.10 MPa or less. In this embodiment, the maximum value of the stress value (absolute value) of the stress value (absolute value) of the compressive stress layer 14 of the glass surface / tensile stress layer 12 can be made 6 or more.

In addition, in the thickness direction of the glass plate 10, the tensile stress of the glass plate 10 in the center part 4/5 (henceforth simply a "tensile center region") of the tensile stress layer 12 except 1/10 of each side is called. It is preferable that the variation of the stress value in the layer 12, that is, the difference between the maximum value and the minimum value of the stress value (absolute value) is 0.12 MPa or less. Thereby, the cutting property of a glass plate can be improved. More preferably, they are 0.10 MPa or less, 0.05 MPa or less, and 0.02 MPa or less. This preferable aspect can also be realized by adjusting the manufacturing conditions of a glass plate and the composition of a glass plate containing the conditions which accelerate | stimulate the volatilization of a volatile component from the surface of the glass ribbon during shaping | molding, or increase the volatilization amount.

Since the stress value of the tensile stress layer 12 formed inside the glass plate 10 is substantially constant in the thickness direction of the glass plate 10, the stress value of the tensile stress layer is compared with the case where the stress value of the tensile stress layer is formed like a parabola in the thickness direction of the glass plate. Thus, the tensile stress layer 12 can be kept thin.

In more detail, the stress value of the tensile stress layer 12 of the glass plate 10 is substantially constant in the thickness direction of the glass plate 10, and compared with the conventional glass plate obtained only in a slow cooling process compared with the maximum value (absolute value) of the stress value. The maximum value (absolute value) of the tensile stress value is large. That is, in the conventional glass plate, the tensile stress layer is formed in a parabolic profile so as to cancel out the compressive stress of the compressive stress layer formed on the glass surface. For this reason, when the thickness of a glass plate becomes thin, the thickness of the tensile stress layer for canceling the compressive stress of the compressive stress layer of a glass surface becomes thin, too, The stress value of a tensile stress layer becomes extremely high in the conventional glass plate, for example, In the case of cutting | disconnection, the scribe line of the predetermined depth put in for cutting may extend out of assumption in the thickness direction of a glass plate, and it may become difficult to divide the glass plate 10 by a desired dimension. However, since the stress value of the tensile stress layer 12 of the glass plate 10 of this embodiment is substantially constant in the thickness direction of the glass plate 10, the maximum value of the stress value of the tensile stress layer becomes difficult to increase and the workability of the glass plate is also highly accurate. I can do it.

When the glass plate 10 is seen from the composition of glass, in the glass plate 10, the Si high concentration area | region (henceforth a Si rich layer) is formed in the depth range which is larger than 0 and 30 nm or less along the thickness direction from the glass surface. The Si rich layer is a region where the concentration ratio of the atomic concentration (atomic%) of Si to the atomic concentration (atomic%) of Si at the center position in the thickness direction of the glass plate 10 is 5% or more. The range where the Si rich layer is located is preferably more than 0 to 25 nm, 2 to 20 nm, 5 to 16 nm, and 8 to 16 nm. On the other hand, the depth of the Si rich layer can be deepened by promoting volatilization from the surface of the molten glass or the glass ribbon in the molding step, but deviation of the molding proper condition or decrease in productivity occurs. Or when the depth of a Si rich layer exceeds 30 nm, it will become difficult to etch when carrying out the etching process to the glass surface of the glass plate 10. Moreover, when the depth of a Si rich layer exceeds 30 nm, the stress value (absolute value) of the compressive stress layer 14 formed in a glass surface will become large, and the problem that the cutability of a glass plate falls. Therefore, it is preferable that the depth of a Si rich layer is 30 nm or less.

The Si rich layer has a maximum peak of Si atom concentration, and the Si atom concentration along the thickness direction of the glass plate 10 decreases toward both sides from the position of the maximum peak. By having such a glass composition, the above-mentioned compressive stress layer 14 and the tensile stress layer 12 are formed. Si atom concentration means the atomic% of Si with respect to the whole glass component (all glass components except oxygen atoms, such as Si, Al, B, Ca, Sr, Ba) except an oxygen atom.

At this time, a volatile component having a higher vapor pressure (saturated vapor pressure) than the SiO ₂ in the glass molten state (for example, the viscosity of the glass at 10 ^4.5 to 10 ⁵ poise or at a temperature of 1100 to 1300 ° C. is the center of the thickness direction of the glass plate. It is preferable to contain 30 mass% or more in a position from the point which forms the said Si rich layer.

When the concentration ratio is less than 5%, a sufficient difference in thermal expansion rate cannot be obtained between the glass surface and the inside, and the compressive stress layer 14 is not effectively formed. Alternatively, sufficient Vickers hardness and durability cannot be obtained.

On the other hand, when the said concentration ratio exceeds 30%, the quality (physical characteristic, thermal characteristic, chemical characteristic) of a glass plate will change, for example, it will become difficult to cut | disconnect or etch a glass plate, and to be unable to use it for a desired use. have. From this point of view, the concentration ratio is preferably 30%.

In addition, the peak position where Si atom content and Si atom concentration become the highest among Si rich layers is located in the range of the depth of 0-5 nm from a glass surface.

By forming the Si rich layer at a depth of greater than 0 and 30 nm or less along the thickness direction from the glass surface, it is possible to obtain a sufficient difference in thermal expansion coefficient between the glass surface and the inside, thereby forming the compressive stress layer 14 on the glass surface. have. Moreover, the Vickers hardness and durability of the glass surface can also be improved, and the glass plate 10 can be prevented from splitting. That is, since Si is a component which improves Vickers hardness, the Vickers hardness of the glass surface of the glass plate 10 becomes high by the Si rich layer formed in the glass surface. In addition, since Si is excellent in chemical resistance, durability of the glass plate 10 in which the Si rich layer is formed on the glass surface is also improved. Moreover, since the Vickers hardness of the glass surface improves compared with the conventional glass plate, a crack incidence rate falls and it can acquire the effect that it is hard to be damaged more and is hard to be damaged.

The Vickers hardness of the glass surface of the glass plate 10 is 4 GPa or more, for example, it is 5 GPa or more, and it is preferable that it is 5.3 GPa or more. Or it is preferable that the Vickers hardness of the glass surface improves 0.01% or more by the ratio with the Vickers hardness in glass, and is improving 0.02% or more, 0.05% or more, 0.10% or more, 1% or more.

Thus, the glass plate 10 has the tensile stress layer 12 and the compressive stress layer 14 in the point of internal stress, and has a Si rich layer near the glass surface in the point of composition. The glass plate 10 is formed from a molten glass or a surface of a glass ribbon in a molding process of a glass ribbon to be described later, for example, in a glass molten state having a glass viscosity of 10 ^4.5 to 10 ⁵ poise or a temperature of 1100 to 1300 ° C. This can be obtained by promoting volatilization of a volatile component having a higher saturated vapor pressure as compared to ₂ .

Each aspect of the above-mentioned preferable numerical range can also be realized by adjusting the manufacturing conditions of the glass plate and the composition of the glass plate, including the conditions for promoting volatilization or increasing the volatilization of the volatile components from the surface of the molten glass or the glass ribbon during molding. have.

Such glass plate 10 may further be chemically strengthened by ion exchange to strengthen the glass surface. The glass plate 10 does not need to be chemically strengthened by ion exchange. Embodiments of the present invention also include tempered glass in which the glass surface of the glass plate 10 is chemically strengthened by ion exchange. In this case, the above-described Si rich layer and the ion exchange treatment region by ion exchange coexist on the glass surface and are formed. An ion exchange treatment area | region is an area | region where ion exchange components, such as Li and Na which are components in a glass surface, were exchanged with ion exchange components, such as K, in the processing liquid for ion exchange. At this time, in the chemically strengthened glass plate 10, a large compressive stress layer is formed by overlapping the compressive stress layer by the chemical strengthening process with the compressive stress layer 14 caused by the Si rich layer. The thickness of the compressive stress layer formed inward from the glass surface by ion exchange is 20 to 100 µm.

The maximum value of the stress value (absolute value) of the compressive stress layer enlarged by ion exchange is preferably 300 MPa or more, and more preferably 400 MPa or more. By making the maximum value of a stress value (absolute value) 300 Mpa or more, the chemically strengthened glass plate 10 can obtain sufficient intensity | strength in order to protect a display etc., for example. In addition, although the said stress value (absolute value) is high, the intensity | strength of glass improves, but the impact when the strengthened glass breaks also increases. In order to prevent an accident due to the impact, the glass plate 10 which has been chemically strengthened has a maximum value of a stress value (absolute value) of the compressive stress layer is preferably 950 MPa or less, more preferably 800 MPa or less, and further 700 MPa or less. desirable. On the other hand, compared with the conventional glass plate which formed the compressive stress layer on the glass surface by quenching glass, the stress value (absolute value) of a tensile stress layer is hard to become large.

The thickness of the compressive stress layer after the chemical strengthening treatment is 20 µm or more, preferably 30 µm or more and 40 µm or more. The larger the thickness of the compressive stress layer, the harder the glass is to be broken even if a deep scratch occurs in the tempered glass, and the variation in mechanical strength becomes smaller. On the other hand, the thickness of a compressive stress layer is 100 micrometers or less. The thickness of the compressive stress layer is preferably 90 µm or less and 80 µm or less in consideration of ease of processing of tempered glass.

In addition, it is preferable that the thickness of the cover glass which applied the glass plate 10 and the tempered glass with which the glass plate 10 was chemically strengthened is 1.5 mm or less. This is because, in the glass plate 1.5 mm or more, the strength of the glass plate itself becomes large, and the compressive stress layer 14 formed in the vicinity of the glass surface does not function sufficiently. That is, it is preferable that the thickness of the glass plate 10 and cover glass formed in this embodiment is 1.0 mm or less, 0.7 mm or less, 0.5 mm or less, and 0.3 mm or less, and the thinner the thickness of the glass plate 10, the effect of this invention. Becomes remarkable.

In addition, the glass plate manufacturing method of this embodiment is suitable for a large glass plate. This is because the warpage amount is as large as that of a large glass plate, and the glass plate is easily broken due to minute scratches caused by handling. However, the occurrence of the problem can be reduced by forming the compressive stress layer 14 on the glass surface. For this reason, the effect of this invention becomes remarkable when the width direction of the glass plate 10 is 1000 mm or more and 2000 mm or more glass plate.

(Kind of the glass of the glass plate)

As the glass used for the glass plate 10, kinds of borosilicate glass, aluminosilicate glass, alumino borosilicate glass, soda-lime glass, alkali silicate glass, alkali aluminosilicate glass, alkali alumino germanate glass and the like are used. Can be. The glass which can be applied to a glass plate of the present invention is not limited to the above type, at least SiO ₂ and the glass melting temperature in (the viscosity of glass 10 ^4.5 to 10 ⁵ poise, or the temperature of 1100 to 1300 ℃) it is possible if the type of glass to the saturated vapor pressure comprises a high volatile component than SiO _2. Al ₂ O ₃ is a mesh forming oxide, and is a component having a relatively low saturated vapor pressure among the components of the glass. However, in this embodiment, since the saturated vapor pressure is higher than that of SiO ₂ , Al ₂ O ₃ is included in the volatile component.

Moreover, it is more preferable that content of the volatile component in glass composition is 30 mass% or more, and it is more preferable that it is 35 mass% or more and 40 mass% or more. Therefore, in the tensile stress layer 12 of the glass plate 10 in which the volatile component of the glass plate 10 does not volatilize, content of a volatile component is 30% mass or more. When content of the volatile component in glass composition is less than 30 mass%, volatilization of a volatile component is not accelerated | stimulated and it becomes difficult to form a Si rich layer and a compressive stress layer on the glass surface. Moreover, when it contains many volatile components, volatilization will increase too much and it will become difficult to homogenize glass. For this reason, it is preferable that content of the volatile component in glass composition is 60 mass% or less, 50 mass% or less, and it is more preferable that it is 45 mass% or less.

(Composition example of each glass)

For example, it is illustrated that an alumino borosilicate glass contains the following components. In addition, the% display of the composition described after this is the mass% display. Alumino borosilicate glass is used for a flat panel display glass substrate, for example. Indication in the following parentheses is a preferable content rate of each component.

SiO ₂ : 50 to 70% (55 to 65%, 57 to 64%, 58 to 62%),

Al ₂ O ₃ : 5-20% (10-20%, 12-18%, 15-18%),

B ₂ O ₃ : 0-15% (5-15%, 6-13%, 7-12%),

At this time, the following composition may be included as an arbitrary component.

MgO: 0 to 10% (lower limit is 0.01%, lower limit is 0.5%, upper limit is 5%, upper limit is 4%, upper limit is 2%),

CaO: 0 to 10% (lower limit is 1%, lower limit is 3%, lower limit is 4%, upper limit is 9%, upper limit is 8%, upper limit is 7%, upper limit is 6%),

SrO: 0 to 10% (lower limit is 0.5%, lower limit is 3%, upper limit is 9%, upper limit is 8%, upper limit is 7%, upper limit is 6%),

BaO: 0 to 10% (upper limit is 8%, upper limit is 3%, upper limit is 1%, upper limit is 0.2%),

ZrO ₂ : 0-10% (0-5%, 0-4%, 0-1%, 0-0.1%).

Moreover, the following composition is illustrated as an alumino borosilicate glass. Indication in the following parentheses is a preferable content rate of each component.

SiO ₂ : 50 to 70% (55 to 65%, 58 to 62%),

Al ₂ O ₃ : 10-25% (15-20%, 15-18%),

B ₂ O ₃ : 5-18% (8-14%, 10-13%),

MgO: 0-10% (1-5%, 1-2%),

CaO: 0-20% (1-7%, 4-7%),

SrO: 0-20% (1-10%, 1-3%),

BaO: 0-10% (0-2%, 0-1%),

K ₂ O: 0-2% (0.1-2%, 0.1-0.5%),

SnO ₂ : 0-1% (0.01-0.5%, 0.01-0.3%).

In addition, it is illustrated that alkali aluminosilicate glass contains the following components. Alkali aluminosilicate glass is used for the cover glass of the display screen of an electronic device, for example. Indication in the following parentheses is a preferable content rate of each component.

SiO ₂ : 50 to 70% (55 to 65%, 57 to 64%, 57 to 62%),

Al ₂ O ₃ : 5-20% (9-18%, 12-17%),

Na ₂ O: 6-30% (7-20%, 8-18%, 10-15%),

At this time, the following composition may be included as an arbitrary component.

Li ₂ O: 0-8% (0-6%, 0-2%, 0-0.6%, 0-0.4%, 0-0.2%),

B ₂ O ₃ : 0-5% (0-2%, 0-1%, 0-0.8%),

K ₂ O: 0 to 10% (lower limit is 1%, lower limit is 2%, upper limit is 6%, upper limit is 5%, upper limit is 4%),

MgO: 0 to 10% (lower limit is 1%, lower limit is 2%, lower limit is 3%, lower limit is 4%, upper limit is 9%, upper limit is 8%, upper limit is 7%),

CaO: 0-20% (lower limit is 0.1%, lower limit is 1%, lower limit is 2%, upper limit is 10%, upper limit is 5%, upper limit is 4%, upper limit is 3%),

ZrO ₂ : 0-10% (0-5%, 0-4%, 0-1%, 0-0.1%).

Moreover, the following composition is illustrated as alkali aluminosilicate glass.

SiO ₂ : 50 to 70%,

Al ₂ O ₃ : 5-20%,

Na ₂ O: 6-20%,

K ₂ O: 0-10%,

MgO: 0-10%,

CaO: greater than 2% to 20%

ZrO ₂ : 0 to 4.8%,

More preferably,

The content of the SiO ₂ content of _{-1 / 2 · Al 2 O 3} : 46.5 to 59%,

CaO / RO (wherein R is at least one selected from Mg, Ca, Sr and Ba), the content ratio is more than 0.3%,

SrO content + BaO content is less than 10%,

(ZrO ₂ + TiO ₂ ) / SiO ₂ content ratio is 0 to less than 0.07,

_{B 2 O 3 / R1 2 O} ( However, R1 is at least one selected from Li, Na and K) The content ratio of 0 to less than 0.1.

Moreover, the following composition is illustrated as other alkali aluminosilicate glass.

SiO ₂ : 58-68%,

Al ₂ O ₃ : 8-15%,

Na ₂ O: 10-20%,

Li ₂ O: 0-1%,

K ₂ O: 1 to 5%,

MgO: 2-10%.

(Each component)

SiO ₂ is a component constituting the skeleton of the glass of the glass plate 10, and has an effect of increasing the chemical durability and heat resistance of the glass. If the SiO ₂ content is too low, the effects of chemical durability and heat resistance cannot be sufficiently obtained. If the SiO ₂ content is too high, the glass is liable to cause devitrification, forming becomes difficult and viscosity increases, making the glass homogeneous.

Al ₂ O ₃ is a component constituting the skeleton of the glass, and has an effect of increasing the chemical durability and heat resistance of the glass. Moreover, it has the effect of improving ion exchange performance and an etching rate. If the Al ₂ O ₃ content is too low, the effects of chemical durability and heat resistance of the glass cannot be sufficiently obtained. On the other hand, Al ₂ O ₃ content is too high, at the same time become difficult to dissolve the acid resistance is reduced by the viscosity of the glass rises.

B ₂ O ₃ is a component that lowers the viscosity of the glass and promotes dissolution and clarification of the glass. If the B ₂ O ₃ content is too low, the higher the viscosity of the glass it is difficult to homogenize the glass.

MgO and CaO are components which reduce the viscosity of glass and promote dissolution and clarification of the glass. Moreover, since the ratio which raises the density of glass is small in alkali earth metal, Mg and Ca are advantageous components in order to improve solubility while reducing the glass which can be obtained. However, when the MgO and CaO content rate becomes too high, the chemical durability of glass will fall.

SrO and BaO are components that lower the viscosity of the glass and promote dissolution and clarification of the glass. Moreover, it is also a component which raises clarity by improving the oxidation property of a glass raw material. However, when SrO and BaO content rate becomes high too much, the density of glass will rise and weight reduction of a glass plate cannot be aimed at, and the chemical durability of glass will fall.

Li ₂ O is a component by lowering the viscosity of glass to improve the solubility and moldability of the glass. In addition, Li ₂ O is a component that improves the Young's modulus of the glass. In addition, Li ₂ O is one of ion exchange components, and among alkali metal oxides, the effect of deepening the depth of the compressive stress layer 14 is high. However, when the content of Li ₂ O is too high, the liquid viscosity is reduced, because the glass is liable to devitrification, the mass production of tempered glass with the down draw method is difficult. Moreover, the thermal expansion coefficient of glass becomes high too much, and the thermal shock resistance of glass falls, and it becomes difficult to match thermal expansion coefficient with peripheral materials, such as a metal and an organic adhesive. Moreover, when ion exchange processing is performed in order to strengthen a glass plate, there exists a problem that deterioration of the ion exchange salt in ion exchange processing becomes quick. When the content of Li ₂ O is too high, the low temperature viscosity of the glass is excessively lowered, so that stress relaxation occurs in the heating step after chemical strengthening and the compressive stress value is lowered, so that sufficient strength cannot be obtained.

Na ₂ O is an essential component, thereby lowering the high temperature viscosity of a glass to improve the melting property and formability of the glass. Moreover, it is a component which improves the devitrification resistance of glass. If the Na ₂ O content is less than 6% by mass, the solubility of the glass decreases and the cost for dissolution increases. In addition, Na ₂ O is an ion exchange component, and when the chemical strengthening treatment is performed, if the Na ₂ O content is less than 6% by mass, the ion exchange performance is also lowered, so that sufficient strength cannot be obtained. In addition, the coefficient of thermal expansion is excessively lowered, making it difficult to match the coefficient of thermal expansion with peripheral materials such as metals and organic adhesives. Moreover, since glass tends to cause devitrification and devitrification resistance also falls, application of the downdraw method which overflows glass becomes impossible, and mass production of stable glass becomes difficult. On the other hand, when the Na ₂ O content is too high, the low temperature viscosity decreases, the thermal expansion rate becomes excessive, the impact resistance decreases, and the thermal expansion coefficient hardly matches with peripheral materials such as metals and organic adhesives. In addition, since the devitrification resistance decreases due to the deterioration of the glass balance also occurs, mass production of stable glass using the downdraw method becomes difficult.

K ₂ O is also a component that lowers the high temperature viscosity of the glass to improve the solubility and formability of the glass and to improve the devitrification resistance. Further, K ₂ O is an ion exchange component, a component capable of improving the ion exchange performance of the glass by containing K ₂ O. However, when the content rate of K ₂ O is too high, the low-temperature viscosity decreases, the thermal expansion rate becomes excessive, and the impact resistance is lowered. Therefore, it is not preferable when applied as a cover glass. In addition, when the content rate of K ₂ O becomes too high, it becomes difficult to match thermal expansion coefficient with peripheral materials, such as a metal and an organic adhesive. In addition, since the devitrification resistance decreases due to deterioration of the glass balance also occurs, mass production of stable glass using the downdraw method becomes difficult.

Li ₂ O, Na ₂ O, and K ₂ O elute from glass to degrade TFT characteristics, and also increase the thermal expansion coefficient of glass to damage the substrate during heat treatment. In the case of containing a large amount, it is not preferable. However, by forcing a specific amount of the above components contained in the glass, the melting of the glass is enhanced while the glass has a high degree of basicity, and the oxidation of the metal which is fluctuated easily while suppressing deterioration of the TFT characteristics and thermal expansion of the glass within a certain range. It is possible to exert clarity by making it.

ZrO ₂ is a component that increases the viscosity and strain point near the devitrification temperature of the glass. Further, ZrO ₂ is also a component for improving the heat resistance of the glass. In addition, ZrO ₂ is a component that significantly improves ion exchange performance. However, when the content of ZrO ₂ is too high, the devitrification temperature rises and the devitrification resistance decreases.

TiO ₂ is a component that lowers the high temperature viscosity of the glass. In addition, TiO ₂ is a component that improves ion exchange performance. However, when the content rate of TiO ₂ becomes too high, devitrification resistance will fall. Moreover, glass is colored and application to the cover glass of the display screen of an FPD glass substrate, an electronic device, etc. is not preferable. In addition, since the ultraviolet ray transmittance decreases from the point at which the glass is colored, a problem arises in that the ultraviolet curable resin cannot be sufficiently cured when the treatment using the ultraviolet curable resin is performed.

In the glass of the glass plate 10, a clarifier can be added as a component which defoases the bubble in glass. The fining agent is not particularly limited as long as the environmental load is small and the glass is excellent in clarity. For example, at least one selected from metal oxides such as tin oxide, iron oxide, cerium oxide, terbium oxide, molybdenum oxide, and tungsten oxide is used as an example. Can be mentioned.

In addition, As ₂ O ₃ and Sb ₂ O ₃ is a material having the effect of clarifying the glass by causing a reaction with a fluctuation in the molten glass, As As ₂ O ₃ and Sb ₂ O ₃ is a material with a large environmental load In view of this, in the glass plate 10 of the present embodiment, As ₂ O ₃ and Sb ₂ O ₃ are not substantially included in the glass. In addition, the As ₂ O ₃ and less than 0.01% is not substantially free of Sb ₂ O ₃ by weight in this specification means that, except for impurities, and containing not intentionally.

(Manufacturing Method of Glass Plate)

Such a glass plate 10 is manufactured using the downdraw method. It is a figure explaining an example of the flow of the manufacturing method of the glass plate of this embodiment. The manufacturing method of a glass plate is a melting process (step S10), a clarification process (step S20), a stirring process (step S30), a molding process (step S40), a slow cooling process (step S50), and a refining process (step S60). It mainly has an over-shape processing process (step S70) and a chemical strengthening process process (step S80).

In the melting process (step S10), a glass raw material is heated by indirect heating by combustion of a fossil fuel and direct heating by electric electricity supply in a melting furnace not shown, and a molten glass is produced. Dissolution of glass may be performed by other methods.

Next, a clarification process is performed (step S20). In the clarification process, the bubble in a molten glass is removed using the above-mentioned clarifier in the state in which the molten glass was stored in the liquid tank which is not shown in figure. Specifically, it performs by the redox reaction of the metal oxide which hydrolyzes in molten glass. In the molten glass at high temperature, the metal oxide releases oxygen by a reduction reaction, and this oxygen becomes a gas to grow bubbles in the molten glass and float on the liquid surface. For this reason, the bubble in a molten glass is defoamed. Or the bubble of oxygen gas introduces and grows the gas in another bubble in a molten glass, and floats on the liquid level of a molten glass. Thereby, the bubble in a molten glass is defoamed. In addition, when the temperature of the glass decreases after defoaming, the metal oxide causes an oxidation reaction to absorb oxygen in the vesicles remaining in the glass without injuries. Oxygen is absorbed and the vesicles become smaller and reabsorbed into the glass.

Next, a stirring process is performed (step S30). In the stirring process, molten glass is passed through a stirring vessel (not shown) which faces vertical to maintain chemical and thermal uniformity of the glass. The molten glass is moved to the vertical bottom at the bottom while being stirred by the stirrer installed in the stirring vessel, leading to the subsequent process. Thereby, the nonuniformity of glass, such as stria, can be suppressed.

Next, a molding step is performed (step S40). In the molding step, the downdraw method is used. The downdraw method including overflow downdraw, slot downdraw, and the like is a known method using, for example, Japanese Patent Application Laid-Open No. 2010-189220, Japanese Patent No. 3586142, or the apparatus shown in FIG. The molding process in the downdraw method is mentioned later. Thereby, the sheet-shaped glass ribbon which has predetermined thickness and width is shape | molded. As the molding method, the overflow downdraw is most preferable among the downdraw methods, but may be a slot downdraw. However, in order to accelerate the volatilization of the volatile component or to increase the volatilization amount to increase the stress value (absolute value) of the compressive stress layer 14, an overflow downdraw having a large amount of volatilization is preferable.

Next, a slow cooling process is performed (step S50). Specifically, the glass ribbon molded into a sheet shape is cooled below the slow cooling point in a slow cooling furnace (not shown) by controlling the cooling rate so that deformation does not occur. Thereby, the glass ribbon has the compressive stress layer 14 and the tensile stress layer 12 by the point of stress similarly to the glass plate 10 which is a final product, and has a Si rich layer from the point of composition.

Next, a trial process is performed (step S60). Specifically, the glass ribbon produced continuously is judged every fixed length, and a glass plate is obtained.

Thereafter, a shape machining step is performed (step S70). In a shape processing process, in addition to cutting out to the size and shape of a predetermined | prescribed glass plate, grinding and polishing of a glass surface and an end surface are performed. The shape processing may use a physical means using a sandblast, a cutter, or a laser, or may use chemical means such as etching. Moreover, when shape-processing a glass plate in a complicated shape, it is preferable to perform the said etching process before a chemical strengthening process.

As an example of the shape process of the glass plate 10, the hole 11 is opened in the glass plate 10 as shown in FIG. 4, and the etching process processed into the outline shape containing a curve and a straight line is mentioned as an example. The glass plate 10 processed into such an outer shape is used for the cover glass of the display screen of an electronic device.

In this case, first, a resist material is coated on both main surfaces of the glass plate. Next, the resist material is exposed through a photomask having a desired contour pattern. The outer shape is not particularly limited, but includes, for example, a part having a negative curvature (a part that bends to the right as it progresses while proceeding toward the left side of the outer shape area along the end of the outer shape). Shape. Next, the resist material after exposure is developed to form a resist pattern in a region other than the etched region of the glass plate, and the etched region of the glass plate is etched. Under the present circumstances, when a wet etchant is used as an etchant, a glass plate is isotropically etched. Thereby, the end surface of a glass plate protrudes most toward the outer side, and the inclined surface which bends gently from both the center part toward both main surface sides is formed. In addition, the boundary between the inclined surface and the main surface and the boundary between the inclined surfaces are suitably rounded.

Although the resist material used in an etching process is not specifically limited, The material which has tolerance with respect to the etchant used when etching glass using a resist pattern as a mask can be applied. For example, since glass generally corrodes by wet etching of aqueous solution containing hydrofluoric acid or dry etching of fluorine-based gas, a resist material having excellent hydrofluoric acid resistance or the like is suitable. As the etchant, a mixed acid containing at least one acid of hydrofluoric acid, sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid can be used. The cover glass of a desired shape can be obtained by using hydrofluoric acid or the said mixed acid aqueous solution as an etchant.

In addition, when performing a shape processing using etching, complicated external shape can also be easily implement | achieved only by adjusting a mask pattern. Moreover, by performing shape processing by etching, productivity can also be improved more and process cost can also be reduced. Moreover, as peeling liquid for peeling a resist material from a glass plate, alkaline solutions, such as KOH and NaOH, can be used. The kind of said resist material, etchant, and peeling liquid can be suitably selected according to the material of a glass plate.

In addition, as an etching method, not only the method of simply immersing in etching liquid, but the spray etching method of spraying etching liquid, etc. can also be used. By shape-processing a glass plate using such an etching, it becomes possible to obtain the cover glass which has an end surface with a high surface roughness. That is, generation | occurrence | production of the micro crack which necessarily arises when shape-formed by machining can be prevented, and the mechanical strength of a cover glass can be improved further.

Finally, the chemical strengthening process by ion exchange is performed (step S80). In addition, a chemical strengthening process is not performed in some cases. For example, chemical strengthening processing is not performed on glass plates, such as alumino borosilicate glass used for a flat panel display. On the other hand, the chemical strengthening process is performed to the glass plate used suitably for the cover glass of the display screen of electronic devices, such as alkali aluminosilicate glass.

The strength of the glass plate 10 can be further improved by chemically strengthening the glass plate 10 in which the Si rich layer and the compressive stress layer 14 were formed in the vicinity of the glass surface. Moreover, compared with the conventional glass plate which forms a compressive stress layer on the surface by quenching glass, the stress value (absolute value) of the tensile stress layer of the glass plate of this embodiment becomes difficult to become large.

In addition, in order to perform the ion exchange treatment, it is preferred that it contains the Na ₂ O or Li ₂ O in the ion exchange component glass composition. In addition to the cover glass of the display screen of an electronic device, the chemically strengthened tempered glass of the present embodiment includes a housing of a mobile terminal device, a cover glass of a solar cell, a glass substrate for a display, a cover glass of a touch panel display, and a touch panel display. It can be applied to a glass substrate or the like.

For example, a chemical strengthening process can be performed using the following method.

In the chemical strengthening treatment, the glass plate 10 is immersed in, for example, about 1 to 25 hours in a treatment bath of 100% KNO ₃ maintained at about 350 to 550 ° C. At this time, the glass plate is chemically strengthened by Na ⁺ ions or Li ⁺ ions in the glass surface layer being ion-exchanged with K ⁺ ions or Li ⁺ ions in the treatment bath. In addition, the temperature, time, ion exchange solution, etc. at the time of an ion exchange process can be changed suitably. For example, two or more types of mixed solutions may be sufficient as an ion exchange solution.

Although the manufacturing method of a glass plate has a washing process and an inspection process other than this, description of these processes is abbreviate | omitted. In addition, although a shape processing process is performed before a chemical strengthening process, you may perform after a chemical strengthening process.

In the shaping | molding process of manufacture of the glass plate 10 of this embodiment, the volatilization of a volatile component is accelerated | stimulated from a glass ribbon, or a Si volatilization layer is formed by the volatilization amount increasing, and it originates in this Si rich layer, and is judged after slow cooling (Iii) The compressive stress layer 14 and the tensile stress layer 12 are formed before the step. A volatile component means a component that is more likely to volatilize than SiO ₂ , that is, a molten glass (for example, a glass viscosity of 10 ^4.5 to 10 ⁵ poise, or a temperature of 1100 to 1300 ° C.), and a component having a saturated vapor pressure higher than that of SiO ₂ . Point. Examples of the volatile component include Al ₂ O ₃ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, SrO, BaO, ZrO ₂ , SnO ₂ , and the like. It is not limited. In addition, B ₂ O ₃ , alkali oxides (Li ₂ O, Na ₂ O, K ₂ O) and alkaline earth metal oxides (MgO, CaO, SrO, BaO) have high volatility, and therefore contain at least one kind as a glass component. It is desirable to. SnO ₂ is volatilized as SnO.

Because volatilization can excessively haejimyeon appropriate shaping of the glass sheet, for example, the upper limit of the content of B ₂ O ₃ is particularly preferably 14% by mass is more preferable, and the 13% by weight. In addition, there is a case that when the content of SnO ₂ is high, the devitrification occurs in the glass. Therefore, from the viewpoint of preventing the devitrification of a glass, the upper limit of the content of SnO ₂ is particularly preferably 0.5 mass% is more preferable, and 0.3% by weight. Further, K ₂ O is used as a dissolution promoter of the glass when added in a large amount is eluted from the glass plate. Thus, when used in a flat panel display glass substrate such as a glass substrate for a liquid crystal display device has the upper limit of the content of K ₂ O is more preferably 0.5% by mass.

Since these volatile components have a saturated vapor pressure higher than SiO ₂ in the molten glass, they are volatilized from the molten glass or the glass ribbon (in a state in which the glass is molten) at the time of molding. That is, in the molding process in which the glass ribbon is formed from molten glass, SiO ₂ in the glass ribbon surface Since other components volatilize, as a result, the Si rich layer in which Si atom concentration becomes higher than Si atom concentration in glass inside is formed in the glass surface after shaping | molding. In addition, when the Si rich layer is formed on the glass surface of the glass plate, the compressive stress layer 14 is formed on the glass surface due to the difference in thermal expansion coefficient with the glass interior.

(Molding device)

It is a figure explaining an example of the shaping | molding apparatus which implements the shaping | molding method by a down-draw method. The shaping | molding apparatus 101 has comprised the cross-sectional shape of the pentagram-shaped wedge shape (narrow baseball groove base shape) which sharpens downward. The shaping | molding apparatus 101 has the upper surface provided with the linearly extended groove 111, the groove 111 provided in this upper surface, and a pair of wall surface 112 facing downward from both parallel ends. In addition, in the present specification, for convenience of description, the direction in which the groove 111 extends on the horizontal plane (the paper vertical direction in FIG. 5) is the X direction, the direction orthogonal to the X direction on the horizontal plane is the Y direction, and the vertical direction is the Z direction. Also referred to as (see FIG. 6).

The groove 111 is gradually shallower in depth toward the other end from one end so as to uniformly overflow the molten glass 103 supplied to one end from the supply pipe (not shown) over the entire length. Each of the pair of wall surfaces 112 has a vertical surface which falls vertically downward from the end in the Y direction of the upper surface, and an inclined surface which inclines inwardly as if approaching each other from the lower end of the vertical surface. Lower ends of these inclined surfaces cross each other to form a ridge line extending in the X direction.

The molding apparatus 101 overflows the molten glass 103 from both sides of the groove 111 and guides the overflowed molten glass onto the wall surface 112 to fuse at the lower end of the inclined surface to form a strip-shaped glass ribbon ( 104) are formed continuously.

The heat insulation structure 102 forms the shaping | molding space (chamber) which accommodates the shaping | molding apparatus 101. FIG. Specifically, the heat insulating structure 102 is made of a material having excellent heat insulating properties, and includes the bottom wall 121 and the ceiling wall 123 facing each other by sandwiching the molding apparatus 101 in the vertical direction, and the bottom wall 121 and the ceiling wall. It has the rectangular cylindrical peripheral wall 122 which connects the periphery of 123. As shown in FIG. In the center of the bottom wall 121, the gate 125 which passes the glass ribbon 104 formed by the shaping | molding apparatus 101 is provided. In addition, the heat insulation structure 102 has a hollow structure, and the air for heating or cooling may be supplied inside.

In this embodiment, as shown in FIG. 5, the some which opposes the wall surface 112 of the shaping | molding apparatus 101, and penetrates the circumferential wall 122 on the upper part of the barrier part of the circumferential wall 122 which faces the Y direction. An outlet 126 is provided. Further, a plurality of inlets 127 penetrating the peripheral wall 122 are provided below the barrier portion in the Y-direction of the peripheral wall 122. For this reason, the flow of air shown by arrows a, b, and c in FIG. 5 is formed by natural convection. That is, air outside the heat insulation structure 102 is introduced into the heat insulation structure 102 through the inlet 127. The introduced air rises along the molten glass 103 flowing down the wall surface 112 of the molding apparatus 101, and then is discharged outside the heat insulating structure 102 through the outlet 126. As such, the volatile components (eg, Al ₂ O ₃ , B ₂ O ₃ , Li ₂ O, Na ₂ O) from the molten glass 103 are raised by raising fresh air introduced from the outside in the heat insulating structure 102. , K ₂ O, MgO, CaO, SrO, BaO, ZrO ₂ , SnO ₂ Etc.) can be promoted. The Si rich layer is formed in the part which volatilized this volatile component, ie, the surface of the molten glass 103 which contact | rises the rising air, when the glass ribbon 104 is cooled. The compressive stress layer 14 is formed by generation of this Si rich layer. In order to raise the stress value (absolute value) of the compressive stress layer 14, it is preferable that the molten glass 103 contains many volatile components.

In addition, the discharge port 126 and the introduction port 127 may be provided in the end wall part which faces the X direction in the circumferential wall 122. As shown in FIG. Alternatively, the discharge port 126 and the introduction port 127 may be provided only at the end wall portion of the peripheral wall 122 that faces the X direction. However, in order to volatilize the volatile components uniformly over the entire width of the molten glass 103, the outlet port 126 and the inlet port 127 are provided at a constant pitch only in the barrier portion facing the Y direction of the peripheral wall 122 It is desirable to have.

In addition, the shape and quantity of the discharge port 126 and the introduction port 127 can be appropriately selected as long as the strength required for the peripheral wall 122 is maintained. For example, the shape of the discharge port 126 and the introduction port 127 may be circular as shown in FIG. 6, and may be made into the slit shape extended in an X direction, and number may be reduced. Moreover, in order to discharge | emit gas from the heat insulation structure 102 uniformly and efficiently, it is more effective to use the slit extended across the width direction of a glass ribbon. However, as the opening area of the slit is widened, the gas flow rate increases excessively, resulting in an increase in surface defects of the glass plate, deterioration of surface irregularities of the glass, and difficulty in securing a molding temperature. However, as shown below, the problem is that the temperature of air or inert gas introduced into the heat insulation structure 102 from the inlet 127 is set as a target temperature inside the heat insulation structure 102, and the heat insulation structure 102 is further described. This can be solved by adjusting the flow rate of the gas so that the internal pressure can be maintained at a predetermined pressure.

Moreover, it is preferable that the air introduce | transduced into the heat insulation structure 102 through the inlet 127 is a temperature which does not reduce the temperature of the molten glass 103 and the glass ribbon 104, for example. Here, if the amount of air introduced is a small amount, even if air of normal temperature is introduced, the temperature of the molten glass 103 and the glass ribbon 104 does not fall by that much. For this reason, air of normal temperature may be introduce | transduced. On the other hand, if the amount of air introduced into the heat insulation structure 102 is large, the temperature of the molten glass 103 and the glass ribbon 104 will fall largely when air of normal temperature is introduce | transduced. In this case, it is preferable that an unillustrated heating device for heating the air introduced through the inlet 127 to a predetermined temperature is provided outside or inside the heat insulating structure 102.

In the shaping | molding apparatus 101 demonstrated above, while the molten glass 103 overflows from both sides of the groove | channel 111 of the shaping | molding apparatus 101 enclosed by the heat insulation structure 102, the wall surface 112 of the shaping | molding apparatus 101 is made. After the air rises along the molten glass 103 flowing down the phase, it is discharged to the outside of the heat insulating structure 102. Here, the air is introduced into the heat insulation structure 102 from the outside of the heat insulation structure 102. Thus, volatilization of the volatile component from the molten glass 103 is accelerated | stimulated as air in the heat insulation structure 102 flows along the molten glass which flows down on the wall surface 112 of the shaping | molding apparatus 101. FIG. Thereby, the glass plate 10 in which the compressive stress layer 14 with high stress value was formed in the front and back both surfaces of the glass of the glass plate 10 can be obtained.

In addition, although the discharge port 126 is provided in the upper part of the circumferential wall 122 in this embodiment, the position of the discharge port 126 is not specifically limited. For example, as shown in FIG. 7, the discharge port 126 may be provided directly above the molding apparatus 101 in the ceiling wall 123. Even in this manner, the air introduced into the heat insulating structure 102 from the outside of the heat insulating structure 102 by natural convection is raised along the molten glass 103 flowing down the wall surface 112 of the molding apparatus 101. It may be discharged to the outside of the heat insulating structure 102 through the outlet 126. In this case, the molten glass 103 is also in contact with the air passing through the heat insulating structure 102 also in the upper part of the molding apparatus 101, so that the outlet port 126 is provided above the peripheral wall 122. Volatilization of the volatile component is further promoted.

However, when the discharge port 126 is provided in the ceiling wall 123, falling objects, such as dust from the upper side of the heat insulation structure 102, may fall to the molten glass 103 through the discharge port 126. From this viewpoint, it is preferable to provide the discharge port 126 in the upper part of the circumferential wall 122 like embodiment shown to FIG. 5,6.

In addition, although the inlet 127 is provided in the lower part of the circumferential wall 122 in embodiment shown to FIG. 5, 6, the position of the inlet 127 is not restrict | limited in particular. For example, as shown in FIG. 8, the introduction port 127 may be provided on the bottom wall 121. In this case, if the inlet 127 is in the region R just under the molding apparatus 101, there is a fear that the flow of air from the inlet 127 will affect the shape stability of the glass ribbon 104. have. For this reason, it is preferable to provide the introduction port 127 outside the area | region R. As shown in FIG.

In addition, the introduction port 127 does not need to be provided as shown in FIG. Even in this manner, air outside the heat insulating structure 102 is introduced into the heat insulating structure 102 through the gate 125. However, in this case, air may pass through the gate 125 in a direction opposite to the glass ribbon 104, and thus the shape stability of the glass ribbon 104 may be impaired. Therefore, the inlet 127 is separated from the gate 125. ) Is preferable.

In addition, in embodiment shown to FIG. 5 thru | or 8, although introduction of the air to the inside of the heat insulation structure 102 by the natural convection, and discharge | emission of the air to the outside of the heat insulation structure 102 are carried out, It is also possible to introduce and discharge. For example, the supply pipe may pass through the lower portion of the heat insulating structure 102 and the discharge pipe may pass through the upper portion of the heat insulating structure 102 to connect a fan to the supply pipe or the discharge pipe. In this case, the ends of the supply pipe and the discharge pipe that open into the space in the heat insulating structure 102 constitute the inlet and the outlet, respectively. In addition, there are other methods of introducing air, for example, by introducing compressed air under reduced pressure through a filter. In addition, the air introduction method is not limited to the above, You may take another air introduction method.

In addition, the gas introduced into the heat insulation structure 102 through the inlet 127 or the gate 125 does not necessarily need to be air, but may be an inert gas. As an inert gas, it is preferable to use nitrogen especially from a viewpoint of preventing corrosion of the shaping | molding apparatus 101 and the heat insulation structure 102. As shown in FIG.

In the embodiment illustrated in FIGS. 5 to 8, the gas is introduced into the heat insulating structure 102, and the gas flows along the direction in which the molten glass 103 or the glass ribbon 104 flows. The density | concentration of the vaporized volatile component in can be reduced. If the gas is not flowed, the volatile components become saturated in the heat insulating structure 102, and thus, the volatilization of the volatile components cannot be further promoted. That is, the gas introduced into the heat insulation structure 102 functions to reduce the concentration of the vaporized volatile component in the heat insulation structure 102. Therefore, the flow of the gas introduced from the outside is not limited to the rise but may be the fall.

Moreover, as another method of promoting volatilization of the volatile component of the molten glass 103 or the glass ribbon 104, the inside of the shaping | molding space inside the heat insulation structure 102 can also be made into a reduced pressure atmosphere. When the molding space inside the heat insulation structure 102 is depressurized, volatilization of volatile components is promoted.

For example, the inside of the heat insulation structure 102 can be depressurized by providing a suction device in the discharge port 126 shown in FIG. In addition, the number of the discharge port 126 provided in the heat insulation structure 102 and the suction apparatus provided is not specifically limited, What is necessary is just to provide one or more.

In addition, if the molding space inside the heat insulating structure 102 is excessively depressurized, gas having a lower temperature than the inside of the heat insulating structure 102 is introduced from the gate 125, and the glass ribbon 104 is not uniformed, and the glass plate 10 Deviation occurs in thickness, and deformation may occur in some cases.

Therefore, it is preferable to depressurize the molding space inside the heat insulation structure 102 in the range of 1/10 or less compared with the inside of the heat insulation structure 102 before pressure reduction. That is, when the atmospheric pressure of the molding space inside the heat insulation structure 102 is 1 atmosphere, it is preferable to reduce the pressure by making the upper limit of the pressure into 0.9 atmosphere.

In this way, the glass ribbon 104 is formed by adjusting the atmosphere of the molding space inside the heat insulation structure 102.

Moreover, as another method of promoting volatilization of the volatile component of the molten glass 103 or the glass ribbon 104, the atmospheric temperature of the shaping | molding space inside the heat insulation structure 102 can also be made high. When the atmospheric temperature of the molding space inside the heat insulating structure 102 rises, the saturated vapor pressure of the volatile components also increases, so that volatilization of the volatile components is promoted.

Moreover, when the atmospheric temperature of the shaping | molding space inside the heat insulation structure 102 rises too much, it becomes difficult to shape | mold the glass ribbon 104, and energy consumption increases. For this reason, it is preferable that the range of the raise of the atmospheric temperature of the shaping | molding space inside the heat insulation structure 102 to raise is more than 0-100 degreeC, It is more preferable that it is more than 0-50 degreeC, It is more than 0-10 degreeC More preferred.

Thus, the partial pressure and volatilization of the volatile component in the atmosphere which faces the surface of the molten glass 103 or the glass ribbon 104 in the heat insulation structure 102 by adjusting the atmosphere of the shaping | molding space in the heat insulation structure 102 inside. Increase the difference in the saturated vapor pressure of the components. Thereby, the glass ribbon 104 is formed, promoting the volatilization of a volatile component. The method of promoting volatilization of volatile components from the surfaces of the molten glass and the glass ribbon may be applied to only one surface in addition to both surfaces of the molten glass and the glass ribbon.

Moreover, as a method of increasing the volatilization amount of the volatile components of the molten glass 103 or the glass ribbon 104, the distance from the lower end part of the shaping | molding apparatus 101 to the upper end part of the gate 125 in a shaping process can be lengthened. have. By lengthening this distance, the passage time through which the glass ribbon 104 passes inside the molding space can be lengthened. As a result, the time for which the glass ribbon 104 is exposed to high temperature in the space inside the heat insulation structure 102 becomes long, and the volatilization time increases. For this reason, the volatilization amount of the volatile component of the glass ribbon 104 increases.

If the distance is made too long, the thickness of the glass ribbon 104 to be molded changes. Therefore, it is more preferable that the increase of the distance is more than 0 to 20 mm, more than 0 to 10 mm, more than 0 to 5 mm, more than 0 to 1 mm, more than 0 to 0.1 mm.

In addition, you may enlarge the size of the molded object 101 itself, and may lengthen the flow length of the wall surface 112 through which the molten glass 103 flows. Thereby, the time which the molten glass 103 is exposed to high temperature in the space inside the heat insulation structure 102 becomes long, and volatilization time increases. For this reason, the volatilization amount of the volatile component of the molten glass 103 increases.

Although various methods for accelerating the volatilization of the volatile components or increasing the volatilization amount from the molten glass passing through the heat insulating structure 102 have been described, these methods can be used alone or in combination.

Since the compressive stress layer 14 is thinly formed on the glass surface, the glass plate 10 manufactured in this way can prevent a wound on the glass surface, maintaining the workability of a glass plate.

In particular, when the glass plate 10 is used for FPD glass substrates, such as a glass substrate for liquid crystal display devices, it cannot contain much alkali metal ion which is an ion exchange component. For this reason, the glass plate 10 is effective at the point which can obtain the compressive stress layer 14, without performing ion exchange. Moreover, since the compressive stress layer 14 which is thinner than the compressive stress layer of the conventional glass plate obtained by quenching glass in a slow cooling process, and has a large stress value (absolute value) can be obtained, the glass plate 10 is a thin glass plate before shape processing. It can be effectively used as.

Conventional glass plates may have scratches on the surface during transport or during cutting or shape processing. However, the glass plate 10 can prevent the scratches on the glass surface before performing chemical strengthening, so that scratches on the cover glass surface can be prevented and the surface quality can be improved.

(Example)

It is a figure which shows distribution of the atomic concentration (%) of Si measured with respect to the glass plate 10 of alumino borosilicate glass. The atomic concentration of Si (%) was measured by using an X-ray photoelectron spectroscopy apparatus (ULTER-PHI, Quantera SXM) to measure the atomic Si concentration near the surface. Specifically, the surface of the glass plate was excavated to various depths by sputtering, and the atomic concentration at each depth was measured. As a measurement element, Al, B, Ca, Sr, and Ba which are volatile components with a relatively high content rate were specified with Si, and the ratio of Si which occupies in a measurement element was calculated | required. These components are volatile components volatilized from the surface of a glass ribbon in the shaping | molding process of a glass ribbon. In addition, among the volatile components, the content of K and Sn is small, and it is considered that the influence of these amounts on the Si atom concentration is small. Therefore, these are not included in the measurement element. The glass plate A and glass plate B shown in FIG. 9 are glass plates produced by changing the conditions of the air which flows using the apparatus shown in FIG.

As shown in FIG. 9, in the glass plate (A) and the glass plate (B), the region where the Si atomic concentration is 5% or more higher than the glass center position is both greater than 0 and 30 nm or less along the thickness direction from the glass surface. Formed. This is considered to be because, in the glass plate A and the glass plate B, the amount of the volatile component decreases in comparison with the inside in the vicinity of the glass surface.

In addition, the content rate (mass%) of each component of the said glass plate (A) and glass plate (B) is as follows.

SiO ₂ 60.9%

Al ₂ O ₃ 16.9%

B ₂ O ₃ 11.6%

MgO 1.7%

CaO 5.1%

SrO 2.6%

BaO 0.7%

K ₂ O 0.25%

SnO ₂ 0.13%

FIG. 10: is a figure which shows distribution of the internal stress measured with respect to the glass plate 10 of the said glass plate A. FIG. The internal stress is an optical path difference ratio of 1 cm per predetermined depth from the surface of the cross section obtained by cutting the glass plate 10 in the thickness direction using a micro-area birefringence meter (KOBRA-CCD / X manufactured by Oji Instrument Co., Ltd.). Optical path difference / optical path length) is measured and calculated by dividing this by the photoelastic constant. In addition, "internal stress" has shown the average value of the thickness of 0-10 micrometers along the thickness direction of a glass plate. Therefore, the stress value exceeding the result shown locally in FIG. 10 may be formed locally.

As shown in FIG. 10, it can be seen that the compressive stress layer 14 is formed on both front and back surfaces of the glass plate 10, and the tensile stress layer 14 having a substantially constant tensile stress value is formed therein. Moreover, it turns out that the stress value of the tensile stress layer 14 formed in the inside of a glass plate is formed substantially constant in the glass plate thickness direction. This is because the volatile component decreases in the glass front and back both surfaces vicinity of the glass plate 10.

In addition, the glass plate 10 produced using the apparatus shown in FIG. 5 was taken out multiple sheets, and it was set as Examples 1-5. In addition, by compressing and removing the compressive stress layer 14 of the glass plate produced by the method similar to Example 1, the compressive and tensile stress profile shape made the glass plate different from Examples 1-5 into the comparative example 1. At the time of manufacture of a glass plate, the glass raw material of alumino borosilicate glass was melt | dissolved at 1580 degreeC using the continuous dissolution apparatus provided with the dissolution tank made of refractory bricks, the adjustment tank made of platinum, etc., clarified at 1650 degreeC, and stirred at 1500 degreeC. After that, a thin glass plate having a thickness of 0.7 mm was formed by the down-draw method using the apparatus shown in FIG. 5. The actual measurement of the Si atomic concentration and the actual stress of the internal stress on the glass plates of Examples 1 to 5 and Comparative Example 1 were performed in the same manner as in the glass plates (A, B).

In addition, a ball chip having a diameter of 0.7 mm (Bosch standard) was installed at the tip of the Ericsen Model 318 (manufactured by Eriksen) scratch durometer under the condition of a scratch load of 2 N and a scratch length of 30 mm. Scratch scratches on the glass plate. Thereafter, the glass surfaces of the glass plates of Examples 1 to 5 and Comparative Example 1 were observed with a laser microscope, and the glass plates in which cracks due to scratches were advanced were evaluated as defective, and the glass plates without cracks were evaluated as good.

Table 1 shows the measured results and evaluation results.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Si rich layer
Depth (nm)
10
8
9
7
9
- Si atomic concentration
Si atom concentration (%) at the peak value (%) / center position

117.70%

116.4%

116.8%

116.2%

117.3%

- Compressive stress layer
Thickness (W ₁ )
(μm)
50
40
45
30
47
- Compressive stress layer
Maximum value of stress value (S ₁ )
(MPa)

2.2

1.6

2.1

1.5

2

- Tensile stress layer
Maximum value of stress value (S ₂ )
(MPa)

0.11

0.11

0.16

0.12

0.13

- Variation of Stress Value in Tensile Center Region
(MPa)
0.08
0.06
0.1
0.05
0.07
- Evaluation of scratches Good Good Good Good Good Bad

From the said Table 1, all the Examples 1-5 are formed the compressive stress layer 14 whose thickness is 50 micrometers or less. For this reason, it is hard to adversely affect the efficiency of the processing process after glass forming. In addition, all of Examples 1-5 evaluated favorable at the evaluation of a flaw. From this point, it turns out that the glass plate 10 does not adversely affect the efficiency of the processing process after glass shaping | molding, and the glass surface is strengthened so that it is hard to damage a glass surface.

In addition, the fluctuation | variation of the stress value in the "tensile center area | region" of the tensile stress layer 12 of Examples 1-5, ie, the difference between the maximum value and minimum value of a stress value (absolute value), are all 0.12 Mpa or less.

In addition, the glass plates of Examples 6-8 and Comparative Example 2 of the composition shown in following Table 2 were chemically strengthened on condition of the following. Comparative Example 2 is a tempered glass obtained by chemically strengthening a part of the compressive stress layer 14 formed on the surface of a glass plate manufactured by the same method as Examples 6 to 8.

The glass plates of Examples 6-8 and Comparative Example 2 melt | dissolve the glass raw material combined so that it may become the composition shown in following Table 2 at 1520 degreeC using the continuous dissolution apparatus provided with the dissolution tank made of refractory bricks, the adjustment tank made from platinum, etc. And it clarified at 1550 degreeC, and after stirring at 1350 degreeC, the thin glass plate of 0.7 mm thickness was shape | molded by the down-draw method using the apparatus shown in FIG. 5, and the glass plate for chemical strengthening was obtained. As for the glass plate of the comparative example 2, the part of the compressive stress layer 14 of the glass plate 10 was surface-polished and removed like the 1st comparative example.

Next, scratches were made to the glass surfaces of the glass plates of Examples 6 to 8 and Comparative Example 2 by the method described above.

The washed glass plate was immersed in about 2.5 hours in a bath of KNO ₃ 100% treatment remains 400 ℃ exchanged K ⁺ ions of the Na ⁺ ions present in the glass surface layer with ions and the treatment bath, a chemical strengthening glass sheets. The glass plate after chemical strengthening was immersed in a washing tank sequentially, and it wash | cleaned and obtained the dried tempered glass.

The glass surfaces of Examples 6-8 and Comparative Example 2 thus obtained were observed with a laser microscope. At this time, the glass plate in which the crack by the scratch advanced was defective and the glass plate in which the crack did not progress was called good.

Table 2 shows the composition and the evaluation results.

Example 6 Example 7 Example 8 Comparative Example 2 SiO ₂ 65.2 65.5 66.0 65.5 Al ₂ O ₃ 8.3 8.0 10.0 8.0 B ₂ O ₃ - - 1.0 - MgO 4.0 8.0 5.0 8.0 CaO 3.5 - 0.8 - Li ₂ O - 0.5 - 0.5 Na ₂ O 15.3 15.8 14.4 15.8 K ₂ O 2.0 1.5 2.8 1.5 ZrO ₂ 1.7 0.7 - 0.7 Evaluation of scratches Good Good Good Bad

From the said Table 2, evaluation of the scratches of Examples 6-8 was favorable, but evaluation of the comparative example 2 was defective. From this point, it can be seen that chemical strengthening of the glass plate 10 having the compressive stress layer 14 and the tensile stress layer 12 is effective in preventing the occurrence of scratches on the surface of the tempered glass.

As mentioned above, although the glass plate of this invention and the manufacturing method of a glass plate were explained in full detail, this invention is not limited to the said embodiment, Of course, various improvement and change may be made in the range which does not deviate from the main point of this invention. .

The glass plate 10 of this invention is suitable for a flat panel display glass substrate. Moreover, the tempered glass which chemically strengthened the glass plate of this invention is used suitably for the cover glass of a mobile telephone, a digital camera, a PDA (portable terminal device), a solar cell, and a flat panel display. Moreover, the glass plate of this invention can expect application to the board | substrate of a touchscreen display, a window glass, the board | substrate for magnetic disks, the cover glass for solid-state image sensors, etc., for example.

10: glass plate
11: hole
12: tensile stress layer
14: compressive stress layer
101: forming apparatus
102: insulation structure
103: molten glass
104: Glass Ribbon
111: Home
112: wall surface
121: bottom wall
122: surrounding wall
123: ceiling wall
125: gate
126 outlet
127: inlet

Claims (23)

It is a glass plate formed by the down draw method,
A Si high concentration region in which the ratio of the atomic concentration (atomic%) of Si to the atomic concentration (atomic%) of Si at the central position in the thickness direction of the glass plate is 5% or more is 0 along the thickness direction from the glass surface. Formed in a range of depth that is larger and less than 30 nm,
The Si high concentration region has a maximum peak of Si atomic concentration, the Si atomic concentration along the thickness direction of the glass plate continuously decreases from the maximum peak position to the surface and the center position of the glass plate,
Further, by the Si high concentration region, a compressive stress layer is formed from the surface of the glass plate to a depth of greater than 10μm in the thickness direction of the glass plate and 50μm or less, the maximum value of the compressive stress layer is 0.1 to 4MPa, characterized in that Glass plate. The method of claim 1,
Glass volatile components with high saturated vapor pressure than SiO ₂ in the molten state, the glass contained in the material of the glass plate is to be more than 30% by mass including in the central position of the thickness direction of the glass plate. 3. The method according to claim 1 or 2,
Glass plate used as glass substrate for flat panel displays. The glass plate of Claim 1 or 2 which contains an alkali metal oxide and is used for the glass substrate for liquid crystal display devices. Melting the glass raw material,
Forming a glass ribbon from the molten glass using the downdraw method;
Cutting the glass ribbon to form a glass plate;
When shaping the glass ribbon, the volatilization of the volatile component from the glass surface is promoted, so that the glass ribbon has an atomic concentration of Si with respect to an atomic concentration (atomic%) of Si at the center position in the thickness direction of the glass plate. A Si high concentration region having a concentration ratio of (atomic%) of 5% or more is formed at a depth of greater than 0 and 30 nm or less along the thickness direction from the glass surface, and the Si high concentration region has a maximum peak of Si atomic concentration, Si atom concentration along the thickness direction of the glass plate is molded to continuously decrease from the maximum peak position to the surface and the center position of the glass plate,
Further, by the Si high concentration region, a compressive stress layer is formed from the surface of the glass plate to a depth of greater than 10 μm in the thickness direction of the glass plate and 50 μm or less, so that the maximum value of the compressive stress layer is 0.1 to 4 MPa, The glass plate is produced, characterized in that the manufacturing method of the glass plate. It is a glass plate molded by the down draw method,
At the time of manufacture of a glass plate, the volatile component of a glass composition is volatilized from the glass surface, and the ratio of the atomic concentration (atomic%) of Si with respect to the atomic concentration (atomic%) of Si in the center position of the thickness direction of the said glass plate is By forming a Si high concentration region of 5% or more, having a tensile stress layer formed inside the glass plate, and a compressive stress layer formed on both sides of the tensile stress layer,
The Si high concentration region is formed in a depth range of greater than 0 and 30 nm or less along the thickness direction from the glass surface, the Si high concentration region has a maximum peak of Si atomic concentration, and the Si atomic concentration along the thickness direction of the glass plate is Decrease toward both sides from the maximum peak position,
The compressive stress layer is formed in a depth range from the surface of the glass plate to more than 10μm along the thickness direction of the glass plate and 50μm or less, the thickness of the compressive stress layer is less than one-third of the thickness of the glass plate,
The absolute value of the stress value of the said compressive stress layer is 4 Mpa or less, The absolute value of the stress value of the said tensile stress layer is 0.4 Mpa or less, The glass plate characterized by the above-mentioned. The glass plate according to claim 6, wherein a difference between the maximum value and the minimum value of the stress value is 0.12 MPa or less in the tensile center region excluding portions of both sides in the thickness direction of the glass plate in the tensile stress layer, respectively. According to claim 6 or claim 7, wherein the glass sheet comprises the tensile stress layer in the glass plate is, the higher the saturated vapor pressure of volatile components as compared to SiO ₂ in the molten state of the glass sheet at least 30% by weight. The glass plate according to claim 6 or 7, wherein the Si atomic concentration along the thickness direction of the glass plate continuously decreases from the maximum peak position to the surface of the glass plate and the center position of the glass plate. Melting the glass raw material,
Forming a glass ribbon from the molten glass using the downdraw method;
Cutting the glass ribbon to form a glass plate;
When shaping a glass ribbon, the volatile component of a glass composition is volatilized from the glass surface, and the ratio of the atomic concentration (atomic%) of Si with respect to the atomic concentration (atomic%) of Si in the center position of the thickness direction of the said glass plate The Si high concentration region, which is 5% or more high, is formed in a range of a depth greater than 0 and 30 nm or less along the thickness direction from the glass surface, has a maximum peak of Si atomic concentration, and the Si atomic concentration along the thickness direction of the glass plate is above. By forming a Si concentration region that decreases from the maximum peak position to both sides,
It is a compressive stress layer formed in the range of the depth which is larger than 10 micrometers and 50 micrometers or less along the thickness direction of the said glass ribbon from the surface of the said glass ribbon, and has thickness less than thirteenth of the thickness of the said glass ribbon, and the absolute value of a compressive stress value is The said glass plate is manufactured so that it may have two compressive stress layers whose value is 4 Mpa or less, and the tensile stress layer which is inserted in the said two compressive stress layers, and whose absolute value of a tensile stress value is 0.4 Mpa or less.


delete delete delete delete delete delete delete delete delete delete delete delete delete

Images