WO2015005000A1

WO2015005000A1 - Float-glass ribbon, float-glass sheet, and method for manufacturing float-glass sheet

Info

Publication number: WO2015005000A1
Application number: PCT/JP2014/063490
Authority: WO
Inventors: 白石　喜裕
Original assignee: 旭硝子株式会社
Priority date: 2013-07-08
Filing date: 2014-05-21
Publication date: 2015-01-15
Also published as: KR102153285B1; TW201502091A; CN105246844A; CN105246844B; KR20160030079A; JP2016164098A

Abstract

A float-glass ribbon having a width of at least 800 mm, and an average sheet thickness of 0.25 mm or less in an intermediate region thereof between a position 400 mm inward in the width direction from one width-direction end thereof, and a position 400 mm inward in the width direction from the other width-direction end thereof, the sheet thickness distribution in the width direction satisfying the expressions T0 ≥ T1 and T0 ≥ T2, where T0 is the sheet thickness at the width-direction center of the intermediate region, T1 is the minimum sheet thickness of a first region at a distance of 0.4 × W or less inward in the width direction from one width-direction end of the intermediate region, T2 is the minimum sheet thickness of a second region at a distance of 0.4 × W or less inward in the width direction from the other width-direction end of the intermediate region, and W is the width of the intermediate region.

Description

Float glass ribbon, float glass plate, and method for producing float glass plate

The present invention relates to a float glass ribbon, a float glass plate, and a method for producing a float glass plate.

The manufacturing method of a float glass plate includes a molding step of forming a float glass ribbon by flowing a molten glass ribbon on a molten metal in a bathtub, and cutting for producing a float glass plate by cutting the float glass ribbon. (For example, refer patent document 1).

In the molding process, the molten glass ribbon having a thickness smaller than the equilibrium thickness tends to shrink in the width direction perpendicular to the flow direction. Therefore, in order to keep the thickness of the molten glass ribbon at a desired thickness, a top roll that applies tension to the molten glass ribbon in the width direction is used.

The top roll is used in pairs and presses both side edges of the molten glass ribbon on the molten metal. A plurality of pairs of top rolls are disposed at intervals along the flow direction of the molten glass ribbon.

The top roll has a rotating member in contact with the molten glass ribbon at the tip. As the rotating member rotates, the molten glass ribbon is sent out in a predetermined direction.

While the tension is applied by a plurality of pairs of top rolls, the molten glass ribbon gradually cools and hardens while flowing in a predetermined direction.

Japanese Unexamined Patent Publication No. 2008-239370

The pair of top rolls applies tension to the molten glass ribbon in the width direction by pressing both side edges of the molten glass ribbon on the molten metal. For this reason, the glass tends to be stretched toward the inner side in the width direction, and the thickness of the glass tends to be thinner toward the inner side in the width direction.

¡After the application of tension by multiple pairs of top rolls is released, the molten glass ribbon shrinks slightly in the width direction. At this time, if the molten glass ribbon has a thin part, stress concentrates on the thin part. And a thin part has a low rigidity, and a wave-like deformation is likely to occur.

This problem was remarkable when a float glass plate having an average plate thickness of 0.25 mm or less was produced. This is because the thickness of the center of the molten glass ribbon in the width direction is thin.

The present invention has been made in view of the above problems, and has as its main object to provide a float glass ribbon or the like that suppresses wavy deformation in the molding process.

In order to solve the above problems, according to one aspect of the present invention,
The width is 800 mm or more, and the average thickness of the intermediate region between the position 400 mm inward in the width direction from one end in the width direction and the position 400 mm inward in the width direction from the other end in the width direction is 0.25 mm or less. A float glass ribbon,
A float glass ribbon is provided in which the thickness distribution in the width direction of the intermediate region satisfies the following formula.
T0 ≧ T1
T0 ≧ T2
T0; plate thickness T1 at the center of the intermediate region in the width direction; minimum plate thickness T2 of the first region at a distance within 0.4 × W from one end in the width direction of the intermediate region; width direction of the intermediate region Minimum thickness W of the second region having a distance of 0.4 × W or less inward in the width direction from the other end; width of the intermediate region

According to one aspect of the present invention, there is provided a float glass ribbon that suppresses wavy deformation in the molding process.

It is sectional drawing which shows the principal part of the float glass plate manufacturing apparatus by one Embodiment of this invention. It is a top view which shows the lower structure of the float glass plate manufacturing apparatus of FIG. It is sectional drawing which shows the float glass ribbon by one Embodiment of this invention. It is sectional drawing which shows the float glass plate by one Embodiment of this invention. It is a figure which shows plate thickness distribution of the float glass plate by the test example 1. FIG. It is a figure which shows plate thickness distribution of the float glass plate by the test example 2. FIG. It is a figure which shows plate thickness distribution of the float glass plate by Test Example 3. It is a figure which shows plate | board thickness distribution of the float glass plate by Test Example 4. It is a figure which shows plate thickness distribution of the float glass plate by Test Example 5. It is a projection pattern formed on the surface of the sample cut out from the center area | region of the float glass plate of the test example 1. FIG. It is a projection pattern formed on the surface of the sample cut out from the center area | region of the float glass plate of the test example 5. FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof is omitted. The “width direction” means a direction orthogonal to the flow direction of the molten glass ribbon in the forming step.

FIG. 1 is a cross-sectional view showing a main part of a float glass sheet manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a plan view showing a lower structure of the float glass sheet manufacturing apparatus of FIG.

The float glass plate manufacturing apparatus 10 forms a plate-like float glass ribbon 14 by causing the molten glass ribbon 12 to flow on the molten metal 11 in the bathtub 20. The molten glass ribbon 12 is gradually cooled and hardened while flowing in the X direction (see FIG. 2), and becomes a float glass ribbon 14. The float glass ribbon 14 is pulled up from the molten metal 11 in the downstream region and sent to a slow cooling furnace.

The float glass plate manufacturing apparatus 10 cuts the float glass ribbon 14 that has been slowly cooled in the slow cooling furnace to produce a float glass plate 16 (see FIG. 4). The float glass plate 16 is obtained by cutting out both thick side edges (so-called ears) of the float glass ribbon 14.

As shown in FIG. 1, the float glass sheet manufacturing apparatus 10 includes a bathtub 20 that houses the molten metal 11, a ceiling 22 that is provided above the bathtub 20, and a side wall 24 that blocks a gap between the bathtub 20 and the ceiling 22, A top roll 40 that applies tension in the width direction to the molten glass ribbon 12 on the molten metal 11 is provided.

The bathtub 20 accommodates the molten metal 11. As the molten metal 11, for example, molten tin is used. In addition to molten tin, a molten tin alloy or the like can also be used, and the molten metal 11 only needs to be able to float the molten glass ribbon 12.

A gas supply path 32 is provided in the ceiling 22, and a heater 34 as a heating source is inserted into the gas supply path 32.

The gas supply path 32 supplies reducing gas to the space above the molten metal 11 to prevent oxidation of the molten metal 11. The reducing gas includes, for example, 1 to 15% by volume of hydrogen gas and 85 to 99% by volume of nitrogen gas.

The heater 34 is provided above the molten metal 11 and the molten glass ribbon 12, and a plurality of heaters 34 are provided at intervals in the flow direction (X direction) and the width direction (Y direction) of the molten glass ribbon 12. The output of the heater 34 is controlled so that the temperature of the molten glass ribbon 12 becomes lower from the upstream side toward the downstream side.

As shown in FIG. 2, the top rolls 40 are used in pairs, pressing both side edges of the molten glass ribbon 12 on the molten metal 11 and applying tension to the molten glass ribbon 12 in the width direction. A plurality of pairs of top rolls 40 are disposed at intervals along the flow direction of the molten glass ribbon 12.

The top roll 40 has a rotating member in contact with the molten glass ribbon 12 at the tip. As the rotating member rotates, the molten glass ribbon 12 is sent out in a predetermined direction.

While the tension is applied by the plurality of pairs of top rolls 40, the molten glass ribbon 12 gradually cools and hardens while flowing in a predetermined direction.

The float glass plate manufacturing method includes a forming step of forming the float glass ribbon 14 by causing the molten glass ribbon 12 to flow on the molten metal 11 in the bathtub 20, and the float glass ribbon 14 by cutting the float glass ribbon 14. And a cutting step for producing 16.

In the present embodiment, the width of the molten glass ribbon 12 on the molten metal 11 in the forming process so that the plate thickness distribution in the width direction of the float glass ribbon 14 (detailed below, the intermediate region 15) satisfies the formula described below. The temperature distribution in the direction (Y direction) is adjusted. This adjustment is performed, for example, by independently controlling the outputs of the plurality of heaters 34 arranged in the width direction of the molten glass ribbon 12.

Generally, the lower the temperature of the molten glass ribbon, the higher the viscosity of the molten glass ribbon, and the molten glass ribbon is less likely to be stretched and the thickness of the molten glass ribbon is less likely to be reduced. Therefore, by applying tension in the width direction to the molten glass ribbon 12 using the top roll 40, and adjusting the temperature distribution in the width direction of the molten glass ribbon 12, a desired plate thickness distribution can be obtained. The float method is suitable for adjusting the plate thickness distribution. In the float process, the molten glass ribbon 12 has a long forming region, and the cooling rate of the molten glass ribbon 12 is slow. Therefore, the temperature distribution of the molten glass ribbon 12 is easy to adjust.

In the present embodiment, a heater for heating the molten glass ribbon 12 is used for adjusting the temperature distribution in the width direction of the molten glass ribbon 12, but a cooler for cooling the molten glass ribbon 12 may be used. Both coolers may be used.

FIG. 3 is a cross-sectional view showing a float glass ribbon according to an embodiment of the present invention. In FIG. 3, the unevenness of the plate thickness is exaggerated for convenience of explanation.

Both main surfaces of the float glass ribbon 14 may be unpolished surfaces. That is, one main surface of the float glass ribbon 14 may be a surface in contact with the inert gas in the molding process. Further, the other main surface of the float glass ribbon 14 may be a surface in contact with the molten metal 11 in the forming process.

The various dimensions of the float glass ribbon 14 can be measured at room temperature before the cutting process. A laser displacement meter can be used to measure the thickness of the float glass ribbon 14. The laser displacement meter measures the plate thickness of the float glass ribbon 14 by receiving reflected light from both main surfaces of the float glass ribbon 14.

The width of the float glass ribbon 14 is 800 mm or more, preferably 2000 mm or more, more preferably 2500 mm or more.

A region between a position 400 mm inward in the width direction from one end in the width direction of the float glass ribbon 14 and a position 400 mm inward in the width direction from the other end in the width direction of the float glass ribbon 14 is referred to as an intermediate region 15. Moreover, the area | region outside the width direction rather than the intermediate | middle area | region 15 of the float glass ribbon 14 is called an outer area | region.

The outer region is in contact with the top roll 40, and the intermediate region 15 is not in contact with the top roll 40. The outer region is thicker than the intermediate region 15 to which tension is applied by the top roll 40.

The average plate thickness of the intermediate region 15 is 0.25 mm or less, preferably 0.15 mm or less, more preferably 0.1 mm or less. The average plate thickness of the intermediate region 15 is preferably 0.03 mm or more, and more preferably 0.05 mm or more. The average plate thickness of the intermediate region 15 is an average value of plate thicknesses measured at a pitch of 50 mm in the width direction.

The plate thickness distribution in the width direction (Y direction) of the intermediate region 15 satisfies the following formula.
T0 ≧ T1
T0 ≧ T2
T0: Thickness T1 of the center of the intermediate region 15 in the width direction; 0.4 × W inward in the width direction from one end in the width direction of the intermediate region 15 (a position 400 mm inward in the width direction from one end in the width direction of the float glass ribbon 14) The minimum thickness T2 of the first region 15L within a distance of 0.4 mm inward in the width direction from the other end in the width direction of the intermediate region 15 (a position 400 mm inward in the width direction from the other end in the width direction of the float glass ribbon 14). The minimum plate thickness W of the second region 15R within a distance of × W; the width of the intermediate region 15 Note that the plate thickness distribution in the X direction of the intermediate region 15 is almost uniform.

The plate thickness distribution in the width direction of the intermediate region 15 uses a result obtained by smoothing a result measured at a 25 mm pitch using a laser displacement meter by a 5-point moving average method in order to remove noise.

The intermediate region 15 may have a symmetrical shape with the center in the width direction as the center, and T1 and T2 may have the same value. Further, at least one of T1 and T2 (both in the present embodiment) may be the minimum plate thickness in the entire width direction of the intermediate region 15.

If the formulas “T0 ≧ T1” and “T0 ≧ T2” are satisfied, the thin portion of the molten glass ribbon 12 on the molten metal 11 is not unevenly distributed in the center in the width direction. Therefore, the stress that can cause the wave-like deformation in the molding process can be dispersed, and the float glass ribbon 14 that suppresses the wave-like deformation in the molding process is obtained.

More preferably, the thickness distribution in the width direction of the intermediate region 15 satisfies the following formula.
T0> T1
T0> T2
If the expressions “T0> T1” and “T0> T2” are satisfied, the molten glass ribbon 12 on the molten metal 11 has a thick center in the width direction and a highly rigid portion exists in the center in the width direction. 12 is hard to shrink in the width direction. Therefore, the wavy deformation in the molding process can be further suppressed.

Further, if the expressions “T0> T1” and “T0> T2” are satisfied, the portions having a thinner plate thickness than the center in the width direction are present on both the left and right sides of the center in the width direction of the molten glass ribbon 12 on the molten metal 11. is there. The presence of a plurality of thin portions can surely disperse the stress that can cause the wave-like deformation, and can surely suppress the wave-like deformation.

A difference ΔT1 between T0 and T1 (a value obtained by subtracting T1 from T0) and a difference ΔT2 between T0 and T2 (a value obtained by subtracting T2 from T0) are each preferably 2 μm or more, more preferably 5 μm or more. It is. ΔT1 and ΔT2 are each preferably 15 μm or less, more preferably 10 μm or less, from the viewpoint of flatness of the float glass plate 16.

As described above, the intermediate region 15 may have a thick plate portion and a thin plate portion alternately along the width direction, and a plurality of thin plate portions spaced apart in the width direction. . Specifically, for example, as shown in FIG. 3, the intermediate region 15 includes a thick part 15 a, a thin part 15 b, a thick part 15 c, and a plate thickness from the left to the right in FIG. 3. The thin portion 15d and the thick portion 15e are in this order. The plurality of

thin portions

15b and 15d only need to be thinner than the adjacent thick portions, and may have the same thickness or different thicknesses. Since a plurality of thin portions, that is, constricted portions are present at intervals in the width direction, stress that can cause wavy deformation can be reliably dispersed, and wavy deformation can be reliably suppressed.

In addition, although the intermediate | middle area | region 15 of this embodiment has two thin parts with the space | interval in the width direction, you may have three or more. Moreover, although the plate | board thickness of the intermediate | middle area | region 15 of this embodiment changes continuously in the width direction, the intermediate | middle area | region 15 may have a part from which plate | board thickness does not change in the width direction.

The float glass ribbon 14 may have a thicker portion than the thinnest portion in the region excluding the center in the width direction.

FIG. 4 is a cross-sectional view showing a float glass plate according to an embodiment of the present invention. In FIG. 4, the uneven thickness is exaggerated for convenience of explanation.

Both main surfaces of the float glass plate 16 may be unpolished surfaces. That is, one main surface of the float glass plate 16 may be a surface in contact with the inert gas in the molding process. Further, the other main surface of the float glass plate 16 may be a surface in contact with the molten metal 11 in the forming process.

The various dimensions of the float glass plate 16 can be measured at room temperature before the cutting process. A laser displacement meter can be used to measure the thickness of the float glass plate 16. The laser displacement meter measures the thickness of the float glass plate 16 by receiving reflected light from both main surfaces of the float glass plate 16.

The float glass plate 16 is produced by cutting off both side edges of the float glass ribbon 14. The float glass plate 16 is produced by cutting the float glass ribbon 14 along its width direction. This cutting may be performed either before or after excision of both side edges of the float glass ribbon 14. For example, the float glass plate 16 can be obtained by cutting the float glass ribbon 14 at a position 400 mm inward in the width direction from both ends in the width direction. The plate thickness distribution of the float glass plate 16 and the plate thickness distribution of the intermediate region 15 of the float glass ribbon 14 are substantially the same.

The float glass plate 16 of the present embodiment can be obtained by cutting the float glass ribbon 14 from the both ends in the width direction at positions separated by 400 mm inward in the width direction, but the cutting position is not particularly limited. If both side edges of the float glass ribbon 14 are cut off, the plate thickness distribution of the float glass plate 16 and the plate thickness distribution of the intermediate region 15 of the float glass ribbon 14 are substantially the same. The thickness is 0.25 mm or less, preferably 0.15 mm or less, more preferably 0.1 mm or less. Further, the average thickness of the float glass plate 16 is preferably 0.03 mm or more, and more preferably 0.05 mm or more. Here, the average plate thickness of the float glass plate is the same value as the average plate thickness of the intermediate region of the float glass ribbon before becoming the float glass plate.

The plate thickness distribution in the width direction (Y direction) of the float glass plate 16 satisfies the following formula.
T0 ′ ≧ T1 ′
T0 ′ ≧ T2 ′
T0 ′; plate thickness T1 ′ at the center in the width direction of the float glass plate 16; minimum plate thickness T2 ′ of the first region 16L having a distance within 0.4 × W ′ from one end in the width direction to the inside in the width direction The minimum thickness W ′ of the second region 16R within a distance of 0.4 × W ′ from the other widthwise end of the float glass plate 16 within the width direction; the width of the float glass plate 16; The thickness distribution in the direction is almost uniform.

The plate thickness distribution in the width direction of the float glass plate 16 uses a result obtained by smoothing a result measured at a 25 mm pitch using a laser displacement meter by a 5-point moving average method in order to remove noise.

The width direction (Y direction) of the float glass plate 16 means the width direction (Y direction) orthogonal to the flow direction (X direction) of the molten glass ribbon 12 in the forming step. By examining the streaks or cross section of the float glass plate 16, the flow direction of the molten glass ribbon 12 in the molding process can be determined.

The float glass plate 16 may have a symmetrical shape about the width direction center, and T1 ′ and T2 ′ may have the same value. Further, at least one of T1 ′ and T2 ′ (both in the present embodiment) may be the minimum plate thickness in the entire width direction of the float glass plate 16.

If the formulas “T0 ′ ≧ T1 ′” and “T0 ′ ≧ T2 ′” are satisfied, the thin portion of the plate thickness on the molten metal 11 in the width direction is not unevenly distributed. Therefore, the stress that can cause the wave-like deformation in the molding process can be dispersed, and the float glass ribbon 14 that suppresses the wave-like deformation in the molding process is obtained, and the high-quality float glass plate 16 is obtained.

The plate thickness distribution in the width direction of the float glass plate 16 more preferably satisfies the following formula.
T0 '>T1'
T0 '>T2'
If the expressions “T0 ′> T1 ′” and “T0 ′> T2 ′” are satisfied, the molten glass ribbon 12 on the molten metal 11 has a thick center in the width direction and a highly rigid portion exists in the center in the width direction. The molten glass ribbon 12 is difficult to shrink in the width direction. Therefore, the wavy deformation in the molding process can be further suppressed.

Further, if the expressions “T0 ′> T1 ′” and “T0 ′> T2 ′” are satisfied, the thickness of the molten glass ribbon 12 on the molten metal 11 on the left and right sides of the center in the width direction is larger than the center in the width direction. There are thin parts. The presence of a plurality of thin portions can surely disperse the stress that can cause the wave-like deformation, and can surely suppress the wave-like deformation.

The difference ΔT1 ′ between T0 ′ and T1 ′ (value obtained by subtracting T1 ′ from T0 ′) and the difference ΔT2 ′ between T0 ′ and T2 ′ (value obtained by subtracting T2 ′ from T0 ′) are preferably It is 2 μm or more, more preferably 5 μm or more. ΔT1 ′ and ΔT2 ′ are each preferably 15 μm or less, more preferably 10 μm or less, from the viewpoint of flatness of the float glass plate 16.

As described above, the float glass plate 16 has thick portions and thin portions that are alternately arranged along the width direction, and a plurality of thin portions that are spaced apart in the width direction. Good. Specifically, as shown in FIG. 4, for example, the float glass plate 16 includes a thick portion 16a, a thin portion 16b, a thick portion 16c, a plate, A thin portion 16d and a thick plate portion 16e are provided in this order. The plurality of

thin portions

16b and 16d only need to be thinner than the adjacent thick portions, and may have the same thickness or different thicknesses. Since there are a plurality of thin portions, that is, constricted portions at intervals in the width direction, the stress that can cause the wavy deformation of the molten glass ribbon 12 can be reliably dispersed in the forming process, and the wavy deformation is ensured. Can be suppressed.

In addition, although the float glass plate 16 of this embodiment has two thin-thick portions at intervals in the width direction, it may have three or more. Moreover, although the plate | board thickness of the float glass plate 16 of this embodiment changes continuously in the width direction, the float glass plate 16 may have a part from which plate | board thickness does not change in the width direction.

The float glass plate 16 may have a thicker portion than the thinnest portion in the region excluding the center in the width direction.

The use of the float glass plate 16 is not particularly limited, and examples thereof include display devices such as liquid crystal panels and organic EL panels, and electronic devices such as solar cells. The float glass plate 16 is used as a substrate for an electronic device, for example.

Since the float glass plate 16 having an average plate thickness of 0.25 mm or less has flexibility, it can be stored, transported, used, and the like by being wound around the winding core into a glass roll. . The glass roll is suitable for manufacturing an electronic device by a roll-to-roll method, and is used as, for example, a substrate for an electronic device. Elements and the like are patterned on the flat glass drawn from the glass roll.

In Test Examples 1 to 5, a float glass ribbon having a width of 2600 mm and an average plate thickness of about 0.1 mm in the middle region was formed by flowing the molten glass ribbon on molten tin, and the formed float glass ribbon was cut. A float glass plate was produced. A float glass plate cut | disconnects the float glass ribbon in the position of 400 mm from the width direction both ends, and excised the area | region outside the cut | disconnected position. Thus, the float glass plate is the same as the middle region of the float glass ribbon. Therefore, the expressions “T0 ′ = T0”, “T1 ′ = T1”, and “T2 ′ = T2” are established.

In Test Examples 1 to 5, a float glass ribbon was molded using the same molding conditions except for the temperature distribution in the width direction of the molten glass ribbon on molten tin. The thickness distribution in the width direction of the obtained float glass plate is shown in FIGS. 5 to 9, the distance in the width direction from one end in the width direction of the float glass plate when the width of the float glass plate is 100% is taken on the horizontal axis, and the plate thickness is taken on the vertical axis.

As is clear from FIGS. 5 to 9, in Test Examples 1 to 4, the expressions “T0 ′ ≧ T1 ′” and “T0 ′ ≧ T2 ′” are satisfied, whereas in Test Example 5, these expressions are Not satisfied. As shown in FIG. 9, the thickness of the float glass plate of Test Example 5 decreases toward the inner side in the width direction, and becomes a minimum value at the center in the width direction.

In order to investigate the presence or absence of wavy deformation in the forming steps of Test Examples 1 to 5, the first region, the second region, and the region between the first region and the second region in each float glass plate were each 300 mm long and horizontal. A 300 mm sample was cut out. The sample was placed on a black surface plate, a tetragonal lattice pattern placed between the sample and the light source was projected onto the sample surface, and the projection pattern formed on the sample surface was photographed. From the presence or absence of distortion of the projection pattern, the presence or absence of wavy deformation in the molding process can be determined. Here, the tetragonal lattice pattern was created by pasting a plurality of colored translucent tapes onto a white translucent board.

Table 1 shows the evaluation results. In Table 1, “A” represents that the projection pattern formed on the surface of the sample has almost no distortion and almost no wavy deformation in the molding process. “B” represents that the projection pattern formed on the surface of the sample is distorted and has a wave-like deformation in the molding process. FIG. 10 is a projection pattern formed on the surface of a sample cut out from the central region of the float glass plate of Test Example 1. FIG. 11 is a projection pattern formed on the surface of a sample cut out from the central region of the float glass plate of Test Example 5.

As is apparent from Table 1, FIG. 10, and FIG. 11, in Test Examples 1 to 4, since the expressions “T0 ′ ≧ T1 ′” and “T0 ′ ≧ T2 ′” are satisfied, the wavy deformation in the molding process Was not recognized. On the other hand, in Test Example 5, both the expressions “T0 ′ ≧ T1 ′” and “T0 ′ ≧ T2 ′” were not satisfied, and a wave-like deformation in the molding process was recognized. The wavy deformation was remarkable in the central region where the plate thickness was thin and the rigidity was low.

As mentioned above, although the embodiment etc. of the manufacturing method of the float glass ribbon, the float glass plate, and the float glass plate were described, the present invention is not limited to the above embodiment etc., and the present invention described in the claims Various modifications and improvements can be made within the scope of the invention.

For example, although the float glass plate 16 of the above-described embodiment has both main surfaces unpolished, at least one main surface may be polished. The polishing process is performed after the cutting process. The polishing method may be a general method. In the case of polishing for the purpose of reducing the surface roughness, ΔT1 ′ and ΔT2 ′ are hardly changed by polishing, although it depends on the polishing conditions.

This application claims priority based on Japanese Patent Application No. 2013-142401 filed with the Japan Patent Office on July 8, 2013. The entire contents of Japanese Patent Application No. 2013-142401 are incorporated herein by reference. To do.

DESCRIPTION OF SYMBOLS 10 Float glass plate manufacturing apparatus 11 Molten metal 12 Molten glass ribbon 14 Float glass ribbon 15 Middle area | region 15L 1st area | region 15R 2nd area | region 16 Float glass plate 16L 1st area | region 16R 2nd area | region 20 Bathtub 22 Ceiling 24 Side wall 32 Gas supply path 34 Heater 40 Top roll

Claims

The width is 800 mm or more, and the average thickness of the intermediate region between the position 400 mm inward in the width direction from one end in the width direction and the position 400 mm inward in the width direction from the other end in the width direction is 0.25 mm or less. A float glass ribbon,
A float glass ribbon in which the thickness distribution in the width direction of the intermediate region satisfies the following formula.
T0 ≧ T1
T0 ≧ T2
T0; plate thickness T1 at the center of the intermediate region in the width direction; minimum plate thickness T2 of the first region at a distance within 0.4 × W from one end in the width direction of the intermediate region; width direction of the intermediate region Minimum thickness W of the second region having a distance of 0.4 × W or less inward in the width direction from the other end; width of the intermediate region
The float glass ribbon according to claim 1, wherein a plate thickness distribution in the width direction of the intermediate region satisfies the following formula.
T0> T1
T0> T2
The float glass ribbon according to claim 1 or 2, wherein the intermediate region has three or more constricted portions spaced apart in the width direction.
A float glass plate having an average plate thickness of 0.25 mm or less,
A float glass plate in which a thickness distribution in the width direction of the float glass plate satisfies the following formula.
T0 ′ ≧ T1 ′
T0 ′ ≧ T2 ′
T0 ′; thickness T1 ′ of the center of the float glass plate in the width direction; minimum thickness T2 ′ of the first region at a distance within 0.4 × W ′ from one end in the width direction of the float glass plate; float glass Minimum thickness W ′ of the second region at a distance within 0.4 × W ′ from the other end in the width direction of the plate in the width direction; width of the float glass plate
The float glass plate of Claim 4 with which the plate | board thickness distribution in the width direction of the said float glass plate satisfy | fills the following formula | equation.
T0 '>T1'
T0 '>T2'
The float glass plate according to claim 4 or 5, wherein the float glass plate has three or more constricted portions at intervals in the width direction.
The float glass plate according to any one of claims 4 to 6, wherein the float glass plate has a thicker portion than a thinnest portion in a region excluding the center in the width direction.
The float glass plate according to any one of claims 4 to 7, wherein the float glass plate is in the form of a glass roll wound in a spiral shape.
By flowing the molten glass ribbon on the molten metal in the bath, the width is 800 mm or more, and the position is 400 mm inward in the width direction from one end in the width direction, and 400 mm inward in the width direction from the other end in the width direction. A forming step of forming a plate-like float glass ribbon having an average plate thickness of 0.25 mm or less in an intermediate region between the separated positions;
Cutting the float glass ribbon to produce a float glass plate,
A method for producing a float glass sheet, wherein the temperature distribution in the width direction of the molten glass ribbon on the molten metal is adjusted in the forming step so that the sheet thickness distribution in the width direction of the intermediate region satisfies the following formula.
T0 ≧ T1
T0 ≧ T2
T0; plate thickness T1 at the center of the intermediate region in the width direction; minimum plate thickness T2 of the first region at a distance within 0.4 × W from one end in the width direction of the intermediate region; width direction of the intermediate region Minimum thickness W of the second region having a distance of 0.4 × W or less inward in the width direction from the other end; width of the intermediate region
The float glass according to claim 9, wherein the temperature distribution in the width direction of the molten glass ribbon on the molten metal is adjusted in the forming step so that the plate thickness distribution in the width direction of the intermediate region satisfies the following formula. A manufacturing method of a board.
T0> T1
T0> T2
The method for manufacturing a float glass sheet according to claim 9 or 10, wherein the adjustment of the temperature distribution in the forming step independently controls outputs of a plurality of heaters arranged in a width direction of the molten glass ribbon.
The method for producing a float glass sheet according to any one of claims 9 to 11, wherein the adjustment of the temperature distribution in the forming step is performed while applying tension in the width direction of the molten glass ribbon.
The method for producing a float glass sheet according to any one of claims 9 to 12, wherein both the heater and the cooler are used for adjusting the temperature distribution in the forming step.