阅读说明：本技术 真空玻璃及其制造方法 (Vacuum glass and manufacturing method thereof ) 是由 竹内昭人 中泽达洋 皆合哲男 于 2019-09-04 设计创作，主要内容包括：本发明提供一种强度高的真空玻璃。真空玻璃具有风冷强化后的第一玻璃板、隔着减压层与上述第一玻璃板对置的风冷强化后的第二玻璃板和以密封上述减压层的方式将上述第一玻璃板的外周缘部与上述第二玻璃板的外周缘部接合的外周密封部。上述外周密封部含有焊料。(The invention provides vacuum glass with high strength. The vacuum glass has a first air-cooled and strengthened glass plate, a second air-cooled and strengthened glass plate facing the first glass plate via a pressure reduction layer, and an outer peripheral sealing portion joining an outer peripheral edge portion of the first glass plate and an outer peripheral edge portion of the second glass plate so as to seal the pressure reduction layer. The outer peripheral sealing portion contains solder.)

1. A vacuum glass, comprising:

a first glass plate after air-cooling strengthening;

a second air-cooled and strengthened glass plate facing the first glass plate with a pressure reducing layer interposed therebetween; and

an outer peripheral sealing portion for joining an outer peripheral edge portion of the first glass plate and an outer peripheral edge portion of the second glass plate in such a manner as to seal the pressure reduction layer,

the outer peripheral seal portion contains solder.

2. The vacuum glass of claim 1, wherein:

the first glass plate and the second glass plate are arranged so that the areas of the main surfaces are substantially the same and the edge surfaces extending in the thickness direction are substantially flush with each other.

3. The vacuum glass of claim 1 or 2, wherein:

the solder is lead-free solder.

4. The vacuum glass according to any one of claims 1 to 3, wherein:

the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction orthogonal to the first direction when viewed from a direction orthogonal to a main surface,

the first glass plate and the second glass plate are warped in the same direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

5. The vacuum glass according to any one of claims 1 to 3, wherein:

the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction orthogonal to the first direction when viewed from a direction orthogonal to a main surface,

the first glass plate and the second glass plate are warped so as to be farther away from each other outward in the second direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

6. The vacuum glass according to any one of claims 1 to 3, wherein:

the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction orthogonal to the first direction when viewed from a direction orthogonal to a main surface,

the first glass plate and the second glass plate are warped so as to be closer to each other toward the outer side in the second direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

7. A method for manufacturing vacuum glass, comprising:

a step of preparing a first glass plate and a second glass plate;

air-cooling and strengthening the first glass plate and the second glass plate respectively;

after the air-cooling strengthening, a step of opposing the first glass plate and the second glass plate so as to form a space therebetween;

bonding an outer peripheral edge portion of the first glass plate and an outer peripheral edge portion of the second glass plate with solder so as to seal the space between the first glass plate and the second glass plate; and

a step of decompressing the space between the first glass plate and the second glass plate by evacuation.

8. The method for manufacturing vacuum glass according to claim 7, wherein:

the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction orthogonal to the first direction when viewed from a direction orthogonal to a main surface,

the first glass plate and the second glass plate which have been opposed through the facing step are warped in the same direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

9. The method for manufacturing vacuum glass according to claim 7, wherein:

the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction orthogonal to the first direction when viewed from a direction orthogonal to a main surface,

the first glass plate and the second glass plate which have been opposed through the facing step are warped so as to be farther away from each other outward in the second direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

10. The method for manufacturing vacuum glass according to claim 7, wherein:

the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction orthogonal to the first direction when viewed from a direction orthogonal to a main surface,

the first glass plate and the second glass plate which have been opposed through the facing step are warped so as to be closer to each other outward in the second direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

Technical Field

The invention relates to vacuum glass and a manufacturing method thereof.

Background

A double glazing in which a pressure-reducing layer is formed between 2 glass plates is also called a vacuum glazing, and is excellent in heat insulation properties. In the manufacturing process of the vacuum glass, the outer peripheral edge portions of the 2 glass plates are sealed in order to secure the decompression layer. The sealing material used at this time is typically a glass frit as shown in patent document 1. The outer peripheral edge portion was sealed by applying a molten glass frit along the outer peripheral edge portions of the 2 glass plates and then solidifying the frit again.

Among these methods, one of the methods for producing a high-strength glass sheet called tempered glass is a forced air cooling tempering method. As shown in patent document 2, the air-cooling tempering method is a method in which a glass plate is heated to a high temperature of about 600 to 700 ℃, and then air is blown onto the surface thereof to quench the glass plate. In this case, the compressive layer is formed on the surface of the glass plate, thereby improving the strength of the glass plate.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2005-231939

Patent document 2: japanese patent laid-open publication No. 2017-48110

Disclosure of Invention

Technical problem to be solved by the invention

The present inventors have studied the production of vacuum glass using a glass sheet which has been air-cooled and strengthened. However, in this case, if the outer peripheral edge portions of the 2 glass plates after air-cooling strengthening are sealed with frits, the strength of the glass plates improved by the air-cooling strengthening is reduced. The reason is that: even in the so-called low-melting-point frit, the melting point of the frit is still high, and the glass plate is heated again to a high temperature by the heat of melting of the frit when sealing the outer peripheral edge portion. Therefore, even when the air-cooled and strengthened glass plate is used, it is difficult to manufacture a high-strength vacuum glass.

The invention aims to: provides a high-strength vacuum glass.

Technical solution for solving technical problem

A vacuum glass according to a first aspect of the present invention includes: a first glass plate after air-cooling strengthening; a second air-cooled and strengthened glass plate facing the first glass plate with a pressure reducing layer interposed therebetween; and an outer peripheral sealing portion for joining an outer peripheral edge portion of the first glass plate and an outer peripheral edge portion of the second glass plate so as to seal the decompression layer. The outer peripheral sealing portion contains solder.

A vacuum glass according to a second aspect of the present invention is the vacuum glass according to the first aspect, wherein the first glass plate and the second glass plate are arranged so that the areas of the main surfaces are substantially the same and the edge surfaces extending in the thickness direction are substantially the same plane.

A vacuum glass according to a third aspect of the present invention is the vacuum glass according to the first or second aspect, wherein the solder is a lead-free solder.

A vacuum glass according to a fourth aspect of the present invention is the vacuum glass according to any one of the first to third aspects, wherein the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction perpendicular to the first direction, when viewed in a direction perpendicular to a main surface. The first glass plate and the second glass plate are warped in the same direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

A vacuum glass according to a fifth aspect of the present invention is the vacuum glass according to any one of the first to third aspects, wherein the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction perpendicular to the first direction, when viewed in a direction perpendicular to a main surface. The first glass plate and the second glass plate are warped so as to be farther away from each other outward in the second direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

A vacuum glass according to a sixth aspect of the present invention is the vacuum glass according to any one of the first to third aspects, wherein the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction perpendicular to the first direction, when viewed in a direction perpendicular to a main surface. The first glass plate and the second glass plate are warped so as to be closer to each other outward in the second direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

A method for manufacturing vacuum glass according to a seventh aspect of the present invention includes the following steps.

(1) A step of preparing a first glass plate and a second glass plate;

(2) a step of air-cooling and strengthening the first glass plate and the second glass plate, respectively;

(3) a step of opposing the first glass plate and the second glass plate to form a space therebetween after the air-cooling tempering;

(4) bonding an outer peripheral edge portion of the first glass plate and an outer peripheral edge portion of the second glass plate with solder so as to seal the space between the first glass plate and the second glass plate;

(5) and a step of reducing the pressure in the space between the first glass plate and the second glass plate by evacuation.

A method for manufacturing vacuum glass according to an eighth aspect of the present invention is the method for manufacturing vacuum glass according to the seventh aspect, wherein the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction perpendicular to the first direction, when viewed from a direction perpendicular to a main surface. The first glass plate and the second glass plate which have been opposed through the facing step are warped in the same direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

A method for manufacturing vacuum glass according to a ninth aspect of the present invention is the method for manufacturing vacuum glass according to the seventh aspect, wherein the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction perpendicular to the first direction, when viewed from a direction perpendicular to a main surface. The first glass plate and the second glass plate which have been opposed through the facing step are warped so as to be farther apart from each other outward in the second direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

A method for manufacturing vacuum glass according to a tenth aspect of the present invention is the method for manufacturing vacuum glass according to the seventh aspect, wherein the first glass plate and the second glass plate each have a substantially rectangular shape having 2 sides extending in a first direction and 2 sides extending in a second direction perpendicular to the first direction, when viewed from a direction perpendicular to a main surface. The first glass plate and the second glass plate which have been opposed through the facing step are warped so as to be closer to each other outward in the second direction at both ends in the second direction when viewed from the first direction in a state where no external force is applied.

Effects of the invention

According to the above aspect of the present invention, the outer peripheral edges of the 2 glass plates after air-cooling strengthening are sealed with solder. Thus, the outer peripheral edge of the glass sheet can be sealed in a low-temperature environment, and the air-cooled and strengthened glass sheet is not excessively reheated. Therefore, the strength of the glass plate after air-cooling strengthening is prevented from being reduced, and the vacuum glass with high strength can be provided.

Drawings

Fig. 1 is a front view of a vacuum glass according to an embodiment of the present invention.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

FIG. 3 is a schematic view of an apparatus for performing air-cooled consolidation.

Fig. 4A is a diagram illustrating a manner of warping of the air-cooled and strengthened glass plate.

Fig. 4B is a diagram illustrating another warping mode of the air-cooled and strengthened glass plate.

Fig. 5 is a diagram illustrating a method of measuring the warp shape at both ends of the glass plate.

FIG. 6A is a graph showing the warp shape at both ends of the long side 1 of 10 glass plates.

FIG. 6B is a graph obtained by measuring the warp shapes of both ends of the long side 2 of 10 glass plates similar to FIG. 6A.

Fig. 7A is a view showing type 1 in which 2 glass plates are opposed to each other.

Fig. 7B is a view showing type 2 in which 2 glass plates are opposed to each other.

Fig. 7C is a view showing type 3 in which 2 glass plates are opposed to each other.

Fig. 8 is a diagram illustrating a step of soldering by the solder supplying apparatus.

FIG. 9A is a graph showing the results of a crushing test performed after heating the air-cooled and strengthened glass plate to 300 ℃.

FIG. 9B is a graph showing the results of a crushing test performed after heating the air-cooled and strengthened glass plate to 350 ℃.

FIG. 10A is a graph showing the relationship between relaxation of strengthening and heating time of a strengthened glass plate having a thickness of 4.6mm at various heating temperatures.

FIG. 10B is a graph showing the relationship between relaxation of strengthening and heating time of a strengthened glass plate having a thickness of 9.5mm at various heating temperatures.

FIG. 11A is a graph showing the results of measuring the amount of warpage at the ends of 5 strengthened glass plates without a Low-E film.

FIG. 11B is a graph showing the results of measuring the amount of warpage at the ends of 2 tempered glass plates having a Low-E film.

Detailed Description

Hereinafter, a vacuum glass and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to the drawings.

< 1. Overall Structure of vacuum glass >

Fig. 1 is a front view of a vacuum glass 1 according to an embodiment of the present invention, and fig. 2 is a side sectional view thereof. The use of the vacuum glass 1 is not particularly limited, and in the present embodiment, the vacuum glass is used as a building material, and is used as a window glass or a door glass of a building. As shown in these figures, the vacuum glass 1 is a glass structure including 2 glass plates 10 and 20. The glass plates 10 and 20 are opposed to each other with the decompression layer 3 interposed therebetween, and arranged such that their main surfaces are parallel to each other. Hereinafter, the side surface (main surface) facing the outside of the glass plate 10 (hereinafter, may be referred to as the first glass plate 10) is referred to as a first surface T1, and the side surface (main surface) facing the inside of the first glass plate 10 (the decompression layer 3 side) is referred to as a second surface T2. The side surface (main surface) facing the inside (pressure reducing layer 3 side) of the glass plate 20 (hereinafter, may be referred to as the second glass plate 20) is referred to as a third surface T3, and the side surface (main surface) facing the outside of the second glass plate 20 is referred to as a fourth surface T4. When installed in a building, the first glass plate 10 is disposed outdoors and the second glass plate 20 is disposed indoors.

The first glass plate 10 and the second glass plate 20 have a substantially rectangular shape having 2 sides extending in the first direction D1 and 2 sides extending in the second direction D2 orthogonal thereto when viewed from the front. The front view means that the glass plates 10 and 20 are viewed from a direction orthogonal to the main surfaces of the glass plates 10 and 20, respectively. The first direction D1 corresponds to the left-right direction in fig. 1, and the second direction D2 corresponds to the up-down direction in fig. 1.

The first glass plate 10 and the second glass plate 20 are arranged so that the areas of the main surfaces are substantially the same and the respective edge surfaces 10a and 20a extending in the thickness direction D3 are substantially flush with each other. The thickness direction D3 is a direction (lateral direction in fig. 2) orthogonal to the main surfaces T1 to T4 of the glass sheets 10 and 20. The edge surface 10a is a surface extending between the outer peripheral edge of the first surface T1 and the outer peripheral edge of the second surface T2 so as to connect them, and the edge surface 20a is a surface extending between the outer peripheral edge of the third surface T3 and the outer peripheral edge of the fourth surface T4 so as to connect them.

Between the first glass plate 10 and the second glass plate 20, a plurality of spacers 30 having substantially the same thickness are arranged on the second surface T2 and the third surface T3, which are surfaces facing the inside of both. The spacers 30 are arranged at positions corresponding to the vertices of the lattice in front view, with a constant interval between the first direction D1 and the second direction D2. The interval between the spacers 30 is preferably 5 to 100mm, more preferably 5 to 80mm, and still more preferably 5 to 60 mm. Further, by these spacers 30, the decompression layer 3 having a constant thickness corresponding to the thickness of the spacers 30 is secured between the second surface T2 (more precisely, the low emissivity film 11 described later) of the first glass plate 10 and the third surface T3 of the second glass plate 20. The pressure-reducing layer 3 is also referred to as a vacuum layer, and is depressurized from a normal atmospheric pressure, typically 1.33Pa or less. Such a pressure reducing layer 3 in a substantially vacuum state suppresses conduction and convection of heat between the outdoor side and the indoor side of the vacuum glass 1, thereby imparting high heat insulating performance to the vacuum glass 1 without causing heat loss from the indoor side to the outdoor side.

The first glass plate 10 of the present embodiment is Low-E glass, and a Low emissivity film (Low-E film) 11 is laminated on substantially the entire surface of the second surface T2. The low emissivity film 11 suppresses heat radiation, and contributes to further improvement of the heat insulating performance of the vacuum glass 1. As a method for forming the low emissivity film 11, a sputtering method is preferably selected from the viewpoint of high performance of the low emissivity film 11 to be formed, but the method is not limited thereto, and for example, a CVD (chemical vapor deposition) method may be selected.

Further, an outer peripheral seal portion 31 is disposed between the first glass plate 10 and the second glass plate 20 along the entire outer peripheral edge portions of the two glass plates 10 and 20. The outer peripheral seal portion 31 is a member for securing a substantial vacuum state of the pressure reducing layer 3, and joins the outer peripheral edge portion of the first glass plate 10 and the outer peripheral edge portion of the second glass plate 20 so as to seal the pressure reducing layer 3 between the two glass plates 10 and 20. The outer peripheral seal portion 31 mainly contains solder and is made of metal. The liquidus temperature of the solder used herein is preferably 300 ℃ or lower, more preferably 250 ℃ or lower, and still more preferably 200 ℃ or lower. The liquidus temperature is a temperature at which the solder is completely dissolved, and can be measured, for example, by Differential Scanning Calorimetry (DSC).

As described above, the outer peripheral seal portion 31 of the present embodiment contains solder. The outer peripheral seal portion 31 may further contain a protective film for protecting the solder. The protective film is made of, for example, resin. The solder is preferably a lead-free solder. For example, a lead-free solder containing Sn and Zn may be used. In addition, the lead-free solder preferably contains at least 1 of Ag, Ti and Al. The content of Sn is preferably 90.0% or more. The preferable content of Zn is 0.001-10%. In addition, the content of Ag is preferably 0 to 6.0%, more preferably 0 to 3.5%. The preferable content of Ti is 0 to 3.0%. The content of Al is preferably 0 to 3.0%, more preferably 0 to 1.0%. The lead-free solder preferably contains at least 1 of Bi, Si, and Sb in an amount of 10% or less in total. The content of Si is preferably 0 to 1.0%, more preferably 0 to 0.1%. In addition, the lead-free solder preferably contains In. The lead-free solder preferably contains at least 1 of Fe, Ni, Co, Ga, Ge, and P, and the total content thereof is preferably 1.0% or less.

The first glass plate 10 and the second glass plate 20 are both tempered glasses that have been air-cooled and tempered, and in the present embodiment, are obtained by air-cooling and tempering float glass plates. That is, the float glass sheet is heated to a high temperature of about 600 to 700 ℃, and then air is blown to the surface thereof to be rapidly cooled, thereby producing the glass sheets 10 and 20. Thereby, a compressive force is generated on the surfaces of the glass sheets 10 and 20, and a tensile force is generated inside, and the strength of the glass sheets 10 and 20 is improved. In addition, not limited thereto, typically, when the crushing test is performed according to JIS (japanese industrial standard) R3206, glass in which the number of pieces in a square area of 50 × 50mm is 40 or more may be referred to as tempered glass.

Fig. 9A and 9B show the results of a crushing test performed on samples obtained by heat-treating air-cooled and strengthened glass plates (TP3) manufactured by japan panel nitre corporation at 2 temperatures. As the heat treatment at this time, the following treatments were performed: the space in which the sample was placed was heated from room temperature, the temperature was raised at a rate of 10 ℃/min to T ℃, and then the temperature was maintained for 30 minutes, and then left to cool and returned to room temperature. The size of the sample was 300 mm. times.300 mm. times.3 mm. Fig. 9A shows the results at 300 ℃ and fig. 9B shows the results at 350 ℃. As is clear from fig. 9A and 9B, the relaxation degree of strengthening when the air-cooled and strengthened glass plate is heated to 300 ℃ is very small as compared with that when it is heated to 350 ℃.

FIGS. 10A and 10B are graphs published in a paper ("Stress relaxation in strengthened Glass)," Glass Technology "(Glass Technology), Vol.18, No. 5, pages 148-151, 1977, month 10), published by Novotny.V and Kavka.J. The line of 0.1 along the horizontal axis is added for the sake of explanation by the applicant. FIGS. 10A and 10B are graphs showing the relaxation of the strengthening of a strengthened glass plate having a thickness of 4.6mm and 9.5mm, respectively, for various heating temperatures. The horizontal axis represents heating time (time), the vertical axis represents the ratio of the current stress to the initial stress (hereinafter referred to as stress ratio), and a smaller value of the stress ratio on the vertical axis means that the strengthening is more relaxed. These graphs show that, for example, if the heating time is about 0.1 hour, the relaxation of the reinforcement does not occur when the heating temperature is 300 ℃ or less. It is also shown that even with a heating time of about 0.1 hour, relaxation of the strengthening can be caused if the heating temperature is 500 ℃ or higher, as is the melting point of the conventional sealing material for sealing the outer peripheral edge portion of the glass plate.

From the above description, it was confirmed that the liquidus temperature of the solder used in the outer peripheral seal portion 31 is preferably 300 ℃. At this time, the outer peripheral edges of the glass sheets 10 and 20 can be sealed at 300 ℃ or lower, the glass sheets 10 and 20 are not excessively reheated, and the strength of the air-cooled and strengthened glass sheets 10 and 20 can be effectively suppressed from being reduced.

The thicknesses (average thicknesses when variations exist) of the first glass plate 10, the second glass plate 20, the pressure-reducing layer 3, and the low emissivity film 11 were d1, d2, d3, and d4, respectively. The value of d 1-d 4 may be appropriately selected depending on the application, and is preferably 0.3 mm. ltoreq. d 1. ltoreq.15 mm, more preferably 0.5 mm. ltoreq. d 1. ltoreq.12 mm, and still more preferably 1 mm. ltoreq. d 1. ltoreq.10 mm. D2 is also the same, and d1 and d2 may be the same or different values. Further, it is preferably 0.03 mm. ltoreq. d 3. ltoreq.1 mm, more preferably 0.05 mm. ltoreq. d 3. ltoreq.0.5 mm, and still more preferably 0.1 mm. ltoreq. d 3. ltoreq.0.3 mm. In addition, it is preferably 50 nm. ltoreq. d 4. ltoreq.600 nm, more preferably 50 nm. ltoreq. d 4. ltoreq.500 nm, and still more preferably 50 nm. ltoreq. d 4. ltoreq.400 nm. When d1 to d4 satisfy the above numerical range, the vacuum glass 1 can be made thin, and the heat insulating performance can be easily improved.

As shown in fig. 1, a through hole 15 is formed in the second glass plate 20 near one corner 1. The through-hole 15 is sealed with a sealing material. The through-hole 15 is used when the space between the glass plates 10 and 20 is evacuated in order to form the decompression layer 3, and is then sealed. As the sealing material for sealing the through-hole 15, for example, solder can be used, and in this case, lead-free solder is preferably used. The through-hole 15 may be formed in the first glass plate 10.

< 2. method of manufacture >

Next, a method for manufacturing the vacuum glass 1 will be described. First, a float glass plate 2 cut into a predetermined shape, which is finally processed into a first glass plate 10 and a second glass plate 20, is prepared. Here, 2 kinds of float glass plates 2 are prepared, and one kind of float glass plate 2 (hereinafter, sometimes referred to as 2 a) is formed with the low emissivity film 11 on one main surface, and finally becomes the first glass plate 10. The low emissivity film 11 is not formed on the other float glass plate 2 (hereinafter, referred to as 2 b), but the surface of the glass is exposed, and the second glass plate 20 is finally formed. In addition, a through hole 15 for vacuum evacuation is formed in float glass plate 2 b.

Subsequently, these float glass plates 2 are air-cooled and strengthened. FIG. 3 is a schematic view of an apparatus for performing air-cooled consolidation. The float glass sheet 2 is conveyed on a roller conveyor 40 including a plurality of rollers 40 a. At this time, the float glass plate 2a is placed on the roller conveyor 40 with the low emissivity film 11 facing upward. First, the float glass sheet 2 is introduced into the heating furnace 45 by the roller conveyor 40, exposed to a high-temperature environment for a predetermined time, and heated to about 600 to 700 ℃. Then, the float glass plate 2 thus heated to a high temperature is introduced into the cooling furnace 46 by the roller conveyor 40. In the cooling furnace 46, air is blown from above and below the surface of the float glass sheet 2 on the roller conveyor 40 by the nozzles 48 for a predetermined period of time, thereby rapidly cooling the float glass sheet 2. As a result, a compressive force is generated on the surface of the float glass plate 2, while a tensile force is generated inside, and as a result, the strength of the float glass plate 2 is improved. In the present embodiment, the roller conveyor 40 reciprocates the float glass sheet 2 in the heating furnace 45 and the cooling furnace 46, respectively, during heating and cooling of the float glass sheet 2.

As shown in fig. 2, the glass plates 10 and 20 included in the vacuum glass 1 are substantially flat plates. However, as described above, in a state where no external force is applied, as shown in fig. 4A and 4B, the float glass sheet 2 after air-cooling strengthening has a shape in which both ends in the second direction D2 are warped when viewed from the first direction D1. That is, both ends of the glass plate 2 are warped through the heating and quenching steps. When air-cooling reinforcement is performed by the above-described apparatus, the directionality of the warpage depends on the conveying direction of the roller conveyor 40, the direction parallel to the conveying direction is the second direction D2, and the first direction D1 is orthogonal to the conveying direction.

When air-cooled tempering is performed by the above-described apparatus, the surface of the float glass sheet 2 not in contact with the roller 40a (the upper surface in fig. 3) is less likely to be stained than the surface in contact with the roller 40a (the lower surface in fig. 3). The stain referred to herein is typically an organic stain such as oil. In fig. 4A and 4B, the surface of the float glass plate 2 indicated by the broken line is not in contact with the roller 40 a. According to the study of the inventors of the present invention, the glass sheet 2 is apt to warp in the same direction mainly at both ends in the second direction D2. In fig. 4A, when a surface not in contact with the roller 40a is taken as an upper surface, both ends in the second direction D2 are warped upward; in fig. 4B, when a surface not in contact with the roller 40a is taken as an upper surface, both ends of the second direction D2 are warped downward. The type of glass sheet 2 to be manufactured tends to depend on the specifications of the glass sheet 2 and the air-cooling and tempering equipment (for example, the size of the glass sheet 2 and the size and interval of the rollers 40 a).

The inventors of the present invention have experimentally dealt with the above inclinationThe process is confirmed. The present inventors produced 10 float glass plates air-cooled and strengthened by the above-described method in the same air-cooling strengthening apparatus, and measured the warp shapes at both ends of these glass plates. The warp shape at both ends was measured as follows. Fig. 5 is a diagram illustrating a method of measuring the warpage shape at both ends. The glass sheet was placed on a metal flat plate so that the side not in contact with the roller faced upward. Then, slide rails are provided along both sides of the glass plate extending in the second direction D2, and a laser displacement meter (LK-G30 manufactured by Keyence corporation) is scanned along the rails in parallel with the both sides. The origin and scanning direction of the measurement are shown in fig. 5. The origin is aligned with the edge of the glass plate with respect to the scanning direction, and since a measurement error occurs at the edge with respect to the direction perpendicular to the scanning direction, the origin is set to be 5mm inside from the edge of the glass plate in order to avoid this. The length of the glass plate in the second direction D2 was 900 mm. The measurement interval is 20mm, and the measurement points are positions 5mm, 25mm, 45mm,. cndot., 865mm, 885mm and 895mm from the origin. Scanning with a laser displacement meter is performed from above the glass plate, and the distance d between the metal plate and the displacement meter at the origin is measured₀Then, the distance d from the laser displacement meter to the upper surface of the glass plate was measured at each measurement point while moving the laser displacement meter. Further, the thickness h of the glass plate was measured. The thickness h was measured at the four corners of the glass plate and the average value was taken. Then, with d_g＝d₀- (h + d), calculating the displacement (distance between the metal plate and the lower surface of the glass plate) d_g。

Will be based on the displacement d_gFig. 6A and 6B show the results of measuring the warp shapes at both ends of (a). FIG. 6A is a graph showing the measurement of the displacement D of one side (long side 1 in FIG. 5) in the second direction D2 of 10 glass plates having a Low-E film_gFIG. 6B is a graph showing the measurement of the displacement D of the other side (long side 2 in FIG. 5) of the glass plate in the second direction D2_gAnd the resulting graph. From 10 glass plates corresponding to fig. 6A and 6B, the type of fig. 4A, that is, the tendency of both ends in the second direction D2 to warp upward was confirmed. In addition, the inventors of the present invention have confirmed that the bar is reinforced by air coolingThe tendency of warping as shown in fig. 4B was exhibited. Although the verification was performed using a glass plate having a Low-E film, it was confirmed that even a normal float glass plate having no Low-E film had a tendency to exhibit warpage as shown in fig. 4A and 4B.

FIG. 11A shows a measurement of the amount of warp d at the ends of 5 tempered glass sheets G1 to G5 without a Low-E film₁FIG. 11B shows the results of measuring the warpage amount d of the end portions of 2 tempered glass plates H1 and H2 having a Low-E film₁And the results obtained. All of the tempered glass sheets G1 to G5, H1 and H2 were float glass sheets, and were air-cooled and tempered by heating at 700 ℃ for 5 minutes. Low-E films of the tempered glass sheets H1 and H2 formed about 85 nm. The sizes of the tempered glass sheets G1 to G5 and H1 and H2 are as follows.

[ Table 1]

In the experiment of fig. 11A and 11B, the amount of warp d from the end of the glass plate₁Together with this, the warp starting position d from the end of the glass sheet was also measured₂. FIGS. 11A and 11B are graphs plotting the warpage amount d₁And a warpage starting position d₂Graph obtained by the relationship of (1). d₁And d₂The measurement was performed using the measurement apparatus described with reference to fig. 5, with the definitions as shown in fig. 4A and 4B. More specifically, a glass plate was placed on a flat metal plate, a rail extending in the second direction D2 was prepared, a laser displacement meter (LK-G30 manufactured by Keyence corporation) was moved in the second direction D2 along the rail, the measurement pitch was set to 20mm, and the distance D from the laser displacement meter to the upper surface of the glass plate was measured at each measurement point. Wherein the measurement pitch in the second direction D2 was set to 2mm from the edge of the glass sheet to the first measurement point and the 4 th measurement point. Further, the distance D was measured in a grid pattern of 20mm × 20mm intervals on the glass plate by repeating the scanning along the second direction D2 at intervals of 20mm in the first direction D1 or more. In addition, with respect to the first direction D1, the direction along the glass plate is not performedScanning of the edge, the inside of the glass plate 5mm from the edge of the first direction D1 was scanned in the second direction D2, and then the scanning in the second direction D2 was repeated at intervals of 20mm in the D1 direction. Scanning with a laser displacement meter was performed from above the glass plate.

Then, a series of values of the distance D measured when each scan is performed along the second direction D2 are sequentially checked along the scanning direction, and a position where the change amount of the value of the distance D is first 0, a position where the value of the distance D changes from the first increase to the decrease, or a position where the value of the distance D changes from the first decrease to the increase is set as the warp start position D₂. For example, the distance D increases only from the first measurement point to the measurement point of 60mm along the second direction D2, but the distance D initially changes from increasing to decreasing at the measurement point of 80mm from the first measurement point. At this time, the warp start position d₂80 mm. On the other hand, the amount of warpage d₁Defined as the distance d measured at the edge and the position d where warping starts₂The difference in the measured distances d.

From the results of fig. 11A and 11B, it was confirmed that warpage can occur at the end of the strengthened glass plate with or without the Low-E film. Wherein it was confirmed that the amount of warpage d of the end portion of the glass plate was not observed in the absence of the Low-E film₁Enlarging; rate d of warping of end portion of glass plate in the presence of Low-E film₁/d₂Becomes larger. It is also found that the amount of warpage d is considered even when the variation in the measurement points is taken into consideration₁And is also approximately within 0.6 mm.

In the experiment of fig. 11A and 11B, the outer peripheral seal portions were formed on the tempered glass plates G1 to G5, H1, and H2 using solder. The surface compressive stress values (average) of the glass sheets G1 to G5, H1 and H2 before and after the heating were measured, and they were not changed before and after the heating, and they were 99MPa, 100MPa, 80MPa, 90MPa, 98MPa and 99MPa, respectively. It was thus confirmed that the strengthening of the strengthened glass plate was not relaxed by the heating with the solder.

Returning to the description of the manufacturing method, after air-cooled tempering, the float glass plate 2a as the first glass plate 10 and the float glass plate 2b as the second glass plate 20 are opposed to each other so that a space as a decompression layer is finally formed therebetween. Specifically, the glass plate 2a is placed on the work table 54 shown in fig. 8, the low emissivity film 11 is directed upward, and the spacers 30 are arranged in a predetermined pattern on the upper surface of the glass plate 2 a. Then, the glass plate 2b is placed thereon. As a preferred embodiment of the type in which the glass plates 2 are opposed to each other, 3 types of fig. 7A to 7C are conceivable. In fig. 7A to 7C, as in fig. 4A and 4B, the surface indicated by the broken line of the float glass sheet 2 is not in contact with the roller 40a in the air-cooling strengthening step.

Fig. 7A is a type (hereinafter, referred to as type 1) in which both ends of the float glass sheet 2 in the second direction D2 are warped in the same direction. Fig. 7B shows a type (hereinafter, referred to as type 2) in which the float glass plate 2 is warped so as to be farther away from each other toward the outside of the second direction D2 at both ends of the float glass plate in the second direction D2. Fig. 7C shows a type (hereinafter, referred to as type 3) in which the float glass plate 2 is warped so as to be closer to each other toward the outer side of the second direction D2 at both ends of the second direction D2. Note that, although the warpage of the glass plate 2 shown in fig. 4A, 4B, and 7A to 7C is emphasized for convenience of explanation, the warpage amount corresponding to the thickness of the glass plate 2 is actually smaller than those figures, and the glass plate 2 can be said to be substantially planar when visually observed. Therefore, which type the glass plate 2 belongs to can be determined as follows.

First, similarly to the measurement method described with reference to fig. 5, the displacement D of the glass plate was measured from the origin in the second direction D2 at a measurement pitch of 20mm_g. Then, in the area of the graphs shown in fig. 6A and 6B, the displacement d is plotted_gA line graph of the measurement points of (1). Then, when a minimum point or a maximum point (hereinafter, referred to as a pole) which appears first is specified on the line graph from the origin along the second direction D2 and the pole is located within 100mm from the origin, it is determined whether the line graph is upward or downward toward the outside in the interval from the origin to the pole. Then, when upward, it is judged that the end portion on the origin side is warped upward along the second direction of the glass sheet; when downward, the end portion is judged to be warped downward. On the other hand, when the pole is not within 100mm from the origin, it is judged that the broken line is within 100mm from the originThe further outward the figure is, either upward or downward. Then, when upward, it is judged that the end portion on the origin side is warped upward along the second direction of the glass sheet; when downward, the end portion is judged to be warped downward. Here, the pole is a point at which the slope of the line graph changes between positive and negative before and after the pole. In addition, the end portion of the glass plate on the opposite side of the origin along the second direction is also determined whether the end portion is warped upward or downward by focusing on the section of 100mm from the end portion in the above line drawing. Then, according to the above operation, the direction of the warp of both end portions of the glass sheet along the second direction is specified based on this specified type of warp.

In type 1 of fig. 7A, the upper glass plate 2 in the figure is a glass plate 2a on which a low emissivity film 11 is formed. That is, the low emissivity film 11 is disposed so as to finally face the pressure reducing layer 3, and is therefore disposed so as to face inward. In type 1, both ends of the second direction D2 are warped in the same direction, and therefore the interval between the glass sheets 2a and 2b is approximately constant at these ends. Therefore, in the step of soldering described later, the introduction plate of the solder is easily inserted between the 2 glass plates 2, and this step is easy. This can provide stable adhesive strength.

However, when the amount of warp at the end of the glass sheet increases, the bonding strength may decrease. Therefore, in type 1 of fig. 7A, the amount of warpage is preferably 0.1mm or more and 0.6mm or less from the viewpoint of facilitating insertion of the lead-in plate of solder and ensuring stable bonding strength. The amount of warp here may be the above-mentioned displacement amount d_gAnd (4) carrying out measurement.

Further, according to the mode of type 1 of fig. 7A, it is possible to manufacture vacuum glass in which a Low-E film is formed only on one glass plate. In this case, as described above, when the Low-E film is provided, the amount of warp at the end of the glass plate is reduced, so that the introduction plate of the solder is easily inserted, and stable adhesion strength can be secured.

In type 2 of fig. 7B, any glass plate 2 may be a glass plate 2 a. In type 2, the space between the glass plates 2a and 2b is open at both ends in the second direction D2. Therefore, in the step of soldering described later, the introduction plate of the solder is easily inserted between the 2 glass plates 2, and this step is easy. In view of this effect, in the case where the vacuum glass 1 is configured by the glass plates 2a and 2b having no Low-E film, that is, having a large amount of warp of the end portion (see the result of fig. 11A), the type 2 can be preferably adopted. In the example of fig. 7B, since the surfaces of the glass plates 2a and 2B on which stains are less attached (surfaces not in contact with the rollers 40 a) are both directed inward, stains do not hinder the step in the step of vacuuming described later, and the step is easily controlled. However, in either or both of the glass sheets 2a and 2b, the surface not in contact with the roller 40a in the air-cooling-strengthening step may be directed outward. In this case, the introduction plate of the solder is easily inserted between the 2 glass plates 2 in the step of soldering, and this step is easy.

As described above, when the amount of warp at the end of the glass sheet increases, the bonding strength may decrease. Therefore, in type 2 of fig. 7B, the amount of warpage is preferably 0.1mm or more and 0.6mm or less from the viewpoint of facilitating insertion of the lead-in plate of solder and ensuring stable bonding strength. The warp amount referred to herein may be the displacement amount d_gAnd (4) carrying out measurement.

With the type 2 configuration of fig. 7B, it is also possible to manufacture vacuum glass in which a Low-E film is formed only on one glass plate. In this case, as described above, when the Low-E film is provided, the amount of warp at the end of the glass plate is reduced, so that the introduction plate of the solder is easily inserted, and stable adhesion strength can be secured. In particular, from the viewpoint of securing the adhesive strength, such vacuum glass is more excellent than the case where both glass plates have no Low-E film.

In type 3 of fig. 7C, any glass plate 2 may be a glass plate 2 a. In type 3, the space between the glass plates 2a and 2b is closed at both ends in the second direction D2. Therefore, in the step of soldering described later, the outer peripheral seal portion 31 of the solder formed between the glass plates 2a and 2b is excellent in that it is not easily peeled off. In view of this effect, the ratio d of the warp of the film having Low-E, that is, the end portion₁/d₂Enlarged (see results in FIG. 11B)In the case where the plates 2a and 2b constitute the vacuum glass 1, type 3 can be preferably used. In the example of fig. 7C, since the surfaces of the glass plates 2a and 2b on which stains are less attached (surfaces not in contact with the rollers 40 a) are both directed inward, stains do not hinder the step in the step of vacuuming described later, and the step is easily controlled. However, in either or both of the glass sheets 2a and 2b, the surface not in contact with the roller 40a in the air-cooling-strengthening step may be directed outward. In this case, the outer peripheral seal portion 31 is also excellent in that it is not easily peeled off. In the mode of type 3, when the amount of warp at the end of the glass sheet becomes too large and the end of the glass sheet can be disturbed, the thickness of the decompression layer may be adjusted to a value that can avoid such a situation.

After being arranged so that the glass plates 2a and 2b are opposed, the outer peripheral edge portions of the glass plates 2a and 2b are joined to each other with solder in such a manner as to seal the space between the glass plates 2a and 2 b. At this time, a solder supplying apparatus 50 as shown in fig. 8 is used. The solder supplying device 50 includes a reservoir 51 for storing the molten solder and a discharge pipe 52 communicating with a hole formed in the bottom surface of the reservoir 51 and discharging the molten solder from the hole. The storage container 51 is provided with a heater 51a for maintaining a molten state of the solder. The front end of the discharge tube 52 is positioned in the space between the outer peripheral edges of the glass plates 2a and 2b, and the introduction plate 53 is inserted into the front end of the discharge tube 52. The introduction plate 53 is a member that guides and introduces the solder between the glass plates 2a and 2 b. The introduction plate 53 protrudes from the discharge tube 52, and the protruding portion is inserted into the space between the glass plates 2a and 2 b. The leading end of the introduction plate 53 may be in the shape of a deformable bellows. In this case, the surfaces of the glass plates 2a and 2b can be welded while being rubbed by the leading end portion of the introduction plate 53, and the joining strength can be improved. Therefore, when the thickness of the leading end portion of the guide plate 53 is d5, d5 > d3 (the thickness of the decompression layer 3) may be provided. The housing 55 supporting the reservoir 51 and the discharge pipe 52 is similarly placed on a table 54 on which the glass plates 2a and 2b are placed, and moves on the table 54 along the outer peripheral edges of the glass plates 2a and 2 b. To assist this movement, the table 54 is provided with a guide rail 56 corresponding to a groove provided in a lower portion of the housing 55.

Next, the space between the glass plates 2a and 2b is evacuated and depressurized. More specifically, the exhaust cup is attached to the glass plate 2a so as to cover the through hole 15 of the glass plate 2 a. Then, the gas molecules in the space between the glass plates 2a and 2b are sucked through the through holes 15 by a pump such as a rotary pump or a turbo molecular pump connected to the exhaust cup. Then, solder as a sealing material is dropped into the through-hole 15, and the surface of the glass plate 2a in the vicinity of the through-hole 15 is bonded to the solder. Thereby, the through-hole 15 is sealed, and the decompression layer 3 is formed between the glass plates 2a and 2 b.

The warp of the glass plates 2a and 2b is removed or relaxed through the vacuum-pumping process, and a substantially flat plate-shaped first glass plate 10 and second glass plate 20 are formed. Through the above operation, the vacuum glass 1 having the pair of glass plates 10 and 20 after air-cooling strengthening is manufactured.

While one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications may be made without departing from the gist thereof.

For example, in the above embodiment, the glass plate 10 is a glass plate having a Low-E film, but may be a normal float glass plate having no Low-E film.

Description of the symbols

1: vacuum glass, 2: float glass plate, 10: first glass plate, 10 a: edge surface, 20: second glass plate, 20 a: edge surface, 3: pressure reducing layer, 30: spacer, 31: outer peripheral seal portion, D1: first direction, D2: second direction, T1: first surface (main surface), T2: second surface (main surface), T3: third surface (main surface), T4: the fourth face (main face).