JP5582446B2 - Film glass manufacturing method and manufacturing apparatus - Google Patents

Description

  The present invention relates to a method and an apparatus for producing a film glass used for a substrate of a flat panel display such as a liquid crystal display or an organic EL display.

  From the viewpoint of space saving, instead of the CRT type display which has been widely used in the past, flat panel displays such as a liquid crystal display, a plasma display, an organic EL display, and a field emission display have become popular in recent years. These flat panel displays are required to be thinner. In particular, organic EL displays are required to be easily carried by folding or winding, and to be usable not only on flat surfaces but also on curved surfaces.

  Further, in a liquid crystal display or an organic EL, an electric circuit pattern such as a thin film transistor (TFT) is formed on the surface of a glass substrate. For this reason, the glass substrate is exposed to a high temperature atmosphere in an electric circuit pattern forming process such as a thin film forming process or a thin film patterning process. When the glass substrate is exposed to a high temperature atmosphere, the structural relaxation of the glass proceeds, so that the volume of the glass substrate shrinks (hereinafter, the shrinkage of the glass is referred to as “thermal shrinkage”). If thermal shrinkage occurs in the glass substrate during the electrical circuit pattern formation process, the shape and dimensions of the electrical circuit pattern formed on the glass substrate will deviate from the design values, and a flat panel display having the desired electrical performance is obtained. It will be difficult.

  For this reason, a glass substrate on which a thin film pattern such as an electric circuit pattern is formed on the surface, such as a glass substrate for a flat panel display, is desired to have a small thermal shrinkage rate. In particular, a glass substrate for a high-definition display including a TFT having a low-temperature polysilicon film is exposed to a very high temperature atmosphere of, for example, 450 ° C. to 600 ° C. when the low-temperature polysilicon film is formed. Since heat shrinkage tends to occur and the electrical circuit pattern has a high definition, even if small heat shrinkage occurs, it tends to be difficult to obtain the desired electrical performance. It is rare.

  Conventionally, as a glass substrate forming method used for a flat panel display or the like, a float method, a down draw method represented by an overflow down draw method described in Patent Document 1, for example, and the like are known.

  In the float method, molten glass is flown out onto a float bath filled with molten tin, and stretched in the horizontal direction to form a glass ribbon. Then, the glass ribbon is gradually cooled in a slow cooling furnace provided downstream of the float bath. This is a method for forming a glass substrate. In the float process, since the conveying direction of the glass ribbon is the horizontal direction, it is easy to lengthen the slow cooling furnace. For this reason, it is easy to make the cooling rate of the glass ribbon in a slow cooling furnace low enough. Therefore, the float method has an advantage that it is easy to obtain a glass substrate having a small heat shrinkage rate.

  However, with the float method, it is difficult to mold a thin glass substrate, and after molding, the surface of the glass substrate must be polished to remove tin adhering to the surface of the glass substrate. There are disadvantages.

  On the other hand, the downdraw method is a method in which molten glass is drawn downward to form a plate shape. In the overflow downdraw method, which is a kind of downdraw method, a glass ribbon is formed by stretching the molten glass overflowing from both sides of a substantially wedge-shaped formed body in a cross section. In the overflow down draw method, the molten glass overflowing from both sides of the molded body flows down along both side surfaces of the molded body and joins below the molded body. Therefore, in the overflow down draw method, the surface of the glass ribbon does not come into contact with anything other than air, and is formed by surface tension. A flat glass substrate can be obtained. Moreover, according to the overflow downdraw method, there is also an advantage that a thin glass substrate (film glass) can be easily formed.

JP 2008-184335 A Japanese translation of PCT publication No. 2004-505881 Special table 2009-511398 gazette JP 2000-335928 A

  However, in the downdraw method, since the molten glass flows downward from the molding equipment, in order to arrange a long slow cooling furnace below the molded body, the molding equipment must be arranged at a high place. However, in practice, the height at which the molding equipment can be arranged is limited due to the height of the ceiling of the factory. For this reason, in the downdraw method, the length dimension of the slow cooling furnace is limited, and it may be difficult to arrange a sufficiently long slow cooling furnace. When the length of the slow cooling furnace is short, the cooling rate of the glass ribbon becomes high, so that it becomes difficult to form a glass substrate having a small heat shrinkage rate.

  For this reason, in general, when a glass substrate having a low thermal shrinkage rate is manufactured using the downdraw method, a heat treatment (off-line annealing) for reducing the thermal shrinkage rate has been performed after molding. Therefore, there are problems that the manufacturing process is complicated and a long time is required for the manufacturing. Therefore, a method capable of directly manufacturing a glass substrate having a small heat shrinkage rate using the downdraw method is desired.

  This invention is made | formed in view of this point, The objective is to provide the manufacturing method and manufacturing apparatus of a film-form glass which can manufacture the film-form glass with a small heat shrinkage | contraction rate by a downdraw method directly. is there.

  The method for producing a film-like glass of the present invention is a method for producing a film-like glass which is formed by forming a molten glass into a film by a down-draw method, slowly cooled and then cut, and the moving direction of the film-like glass is changed during the slow cooling. The direction is changed in the horizontal direction. The “film-like glass” in the present invention means a thin glass having a thickness of 200 μm or less. “Slow cooling” means a state where the temperature is lowered while temperature control is being performed. Therefore, the glass in the slow cooling furnace is understood as “under slow cooling” in the present invention.

  In this invention, it is preferable to shape | mold so that the thickness of film-form glass may be 100 micrometers or less.

  According to the said structure, since the flexibility of glass becomes very large, the moving direction of a film-form glass can be easily changed into a horizontal direction during slow cooling. Further, it is possible to provide a film-like glass that meets the demand for flat panel thinning.

  In the present invention, it is desirable to use the overflow downdraw method as the downdraw method.

  According to the said structure, it becomes possible to produce the film-form glass excellent in surface quality. Moreover, it is easy to produce a film glass having a small thickness.

  In this invention, it is preferable to cut | disconnect, after winding up film-form glass and using it as a roll.

  According to the said structure, film-like glass with a small heat shrinkage rate can be provided with a roll form.

  An apparatus for producing a film-like glass according to the present invention includes a slow cooling furnace for slowly cooling glass formed into a film by the downdraw molding apparatus, and a cutting device for cutting the film-like glass that has passed through the slow cooling furnace into a predetermined length. An apparatus for producing a film-like glass, wherein the moving direction of the film-like glass is changed from a vertical direction to a horizontal direction in a slow cooling furnace.

  In the present invention, the downdraw molding apparatus is preferably an overflow downdraw molding apparatus.

  According to the said structure, it becomes possible to produce the film-form glass excellent in surface quality. Moreover, it is easy to produce a film glass having a small thickness.

  In the present invention, it is preferable to further include a winding device for winding the film-like glass into a roll.

  According to the said structure, film-like glass with a small heat shrinkage rate can be provided with a roll form.

  According to the present invention, since the slow cooling is continued after the moving direction of the film-like glass is changed to the horizontal direction, the time and distance required for the slow cooling can be sufficiently secured. Therefore, although the downdraw method is employed, the cooling rate of the film-like glass can be made sufficiently low, and a film-like glass having a small heat shrinkage rate can be produced.

FIG. 1 is an explanatory view showing an example of the manufacturing apparatus of the present invention. It is a schematic diagram for demonstrating the measuring method of a thermal contraction rate.

  The method for producing a film-like glass of the present invention includes a forming step of drawing the glass downward by a downdraw method and continuously forming it into a film shape. More specifically, the glass drawn out from the molding apparatus is drawn downward until it reaches a predetermined thickness while the shrinkage in the width direction is restricted by the cooling roller.

  In the present invention, it is not particularly limited as long as it is a downdraw method, but it is preferable to employ an overflow downdraw method because it can produce a glassy glass that is unpolished and has good surface quality. The reason why a film-like glass having a good surface quality can be produced is that the surface to be the surface of the film is not in contact with anything other than air and is molded in a free surface state. Here, the overflow down draw method is a film-like shape in which the molten glass overflows from both sides of the heat-resistant bowl-shaped structure, and the molten glass overflows and merges at the lower end of the bowl-shaped structure, and is stretched and formed downward. A method for producing glass. The structure and material of the bowl-shaped structure are not particularly limited as long as the quality required for the intended use of the dimensions and surface accuracy of the film-like glass can be realized. Further, the downward stretching may be performed by applying a force to the film-like glass by any method. For example, a method may be adopted in which a heat-resistant roller having a sufficiently large width is rotated and stretched in contact with the film-like glass, or a plurality of pairs of heat-resistant rollers are attached to the end face of the film-like glass. You may employ | adopt the method of making it contact only in the vicinity and extending | stretching.

  In addition to the overflow downdraw method, various molding methods can be employed. For example, various molding methods such as a downdraw method (slot down method, redraw method, etc.) can be employed.

By the way, as the thickness of the glass decreases, the amount of heat of the glass itself decreases, so that in the downdraw method, the glass is likely to cool during drawing, in other words, the viscosity is likely to increase. In particular, when trying to form a film-like glass having a final wall thickness of 100 μm or less, the glass away from the molding equipment (molded body in the case of the overflow down draw method) is shrunk in the plate width direction by the surface tension. At the same time, the viscosity rises remarkably due to a rapid temperature drop. Therefore, in order to secure a necessary plate width or to obtain a desired thickness, for example, in the overflow downdraw method, the viscosity of the glass immediately after being drawn from the molded body is 10 ^5.0 dPa · s or less, particularly 10 ^4.8 dPa · s or less, 10 ^4.6 dPa · s or less, 10 ^4.4 dPa · s or less, 10 ^4.2 dPa · s or less, heating so as to be 10 ^4.0 dPa · s or less, It is preferable to control the temperature by taking measures such as heat insulation. By controlling the temperature in this way, the plate width can be increased without being damaged even if a tensile stress is applied in the plate width direction. Furthermore, it becomes possible to extend downward easily. On the other hand, if the viscosity of the glass is too low, the film-like glass is likely to be deformed, and the quality such as warpage and undulation deteriorates. Moreover, since the temperature of the glass to be stretched becomes high, the subsequent cooling rate is increased, and the thermal shrinkage of the glass may be increased. Therefore, the viscosity of the glass is preferably 10 ^3.5 dPa · s or more, 10 ^3.7 dPa · s or more, 10 ^3.8 dPa · s or more, 10 ^3.9 dPa · s or more.

The method for producing a film-like glass of the present invention includes a step of gradually cooling the film-like glass. During slow cooling, an increase in the cooling rate of the glass is not preferable because the thermal shrinkage rate increases. On the other hand, if the cooling rate is too slow, the productivity deteriorates. Or since the slow cooling area in a manufacturing process becomes unduly long, it is not preferable. In order to reduce the thermal shrinkage efficiently, the viscosity of the glass is 10 ¹⁰ to 10 ^14.5 dPa · s, particularly 10 ¹¹ to 10 ¹⁴ dPa · s, more preferably 10 ¹² to 10 ¹⁴ dPa · s. The average cooling rate is preferably 100 ° C./min or less, particularly 80 ° C./min or less, 50 ° C./min or less, 30 ° C./min or less, or 20 ° C./min or less. The average cooling rate is preferably 1 ° C./min or more, 2 ° C./min or more, 5 ° C./min or more, 10 ° C./min or more. Here, the “average cooling rate” is obtained by dividing the temperature range corresponding to the viscosity range of the glass by the time required for the glass to pass.

  Furthermore, in the present invention, the moving direction of the film-like glass is changed from the lower side to the horizontal direction during the slow cooling. By turning the film glass during slow cooling, sufficient time and distance can be used for slow cooling to achieve the desired thermal shrinkage. That is, there is no height restriction, which is a particular problem when the downdraw method is adopted.

  In order to change the direction of the film-like glass moving downward in the horizontal direction, various methods can be employed. For example, as disclosed in Patent Document 2, a method of changing the direction along a roller conveyor made up of a large number of rollers, or as disclosed in Patent Document 3, only an edge portion of a film is used with an air conveyor. A method of guiding and changing directions can be adopted. Moreover, you may change direction by making it curve freely like patent document 4. FIG.

  What is necessary is just to adjust the curvature radius of the film-form glass required for direction change according to the thickness of a film. That is, it is necessary to increase the radius of curvature as the thickness of the film increases, and conversely as the thickness decreases, the radius can be decreased. For example, in the case of a film-like glass having a thickness of 100 μm, the curvature radius is appropriately about 50 mm to 200 mm.

  The method for producing a film-like glass of the present invention preferably includes a step of cutting the film-like glass, which has been gradually cooled, into a predetermined length. The cutting referred to here is not limited to the case where the film-like glass is cut into every leaf. That is, in the case where a roll process described later is employed, cutting for cutting off the film-like glass accompanying roll replacement is included. In addition, various methods, such as a method of cutting a scribe line with a cutter or laser light in advance and then bending, or a method of fusing with laser light, can be employed for cutting.

  The manufacturing method of the film-like glass of this invention can be further equipped with the process cut | disconnected, after winding up film-like glass and making it into a roll form. In this case, it is desirable to take up with the interleaving paper in order to prevent the generation of scratches due to contact between the film-like glasses and to absorb the external pressure applied to the roll. For example, in the case of film glass having a thickness of 100 μm, the minimum radius of curvature during winding is preferably 200 mm or less, particularly 150 mm or less, 100 mm or less, 70 mm or less, 50 mm or less, particularly 30 mm or less. By reducing the radius of curvature, packing and transport efficiency can be improved.

  In addition to the above steps, various steps can be provided as necessary. For example, after completion of slow cooling, an end separation step of separating the end (so-called ear portion) of the film-like glass can be provided. In this step, a method of continuously cutting and separating the edge of the glass by irradiating a laser beam can be suitably employed. In this case, a carbon dioxide laser or a YAG laser or the like may be used as the laser to be used. It is preferable to adjust the laser output so that the progress rate of the cracks progressed by the laser matches the drawing speed of the glass. Speed ratio = (speed of crack progressed by laser−plate drawing speed) / (plate drawing speed) × 100 is ± 10% or less, ± 5% or less, ± 1% or less, ± 0.5% or less, ± 0. It is preferable that it is 1% or less.

  It is also possible to employ a polishing step for polishing the surface of the film glass. However, when the overflow down draw method is adopted, the surface of the glass is a fire-making surface, so that the surface quality is extremely high and a polishing step is not necessary. Furthermore, it is preferable to use it in an unpolished state because the mechanical strength of the glass is increased. In other words, the theoretical strength of glass is inherently very high. However, even a stress much lower than the theoretical strength often leads to fracture. The reason is that a small defect called Griffith flow occurs on the glass surface in a process after the glass molding, for example, a polishing process.

  The thickness of the film-like glass produced by the above method is not particularly limited, but the thickness is 100 μm or less, particularly 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, It is preferably 20 μm or less and 10 μm or less. The thinner the film glass, the lighter the device. Moreover, since the stress value generated when the glass is bent is lowered, the radius of curvature required for the direction change of the film-like glass can be reduced. The same applies to the case where the film glass is wound into a roll. In addition, when laser cutting is employed for cutting off the end portion, it is possible to reduce the required output. Alternatively, if the output is constant, cutting can be performed at a higher speed. However, when the thickness is less than 1 μm, the mechanical strength of the glass cannot be maintained. Further, deformation may occur due to a subtle air flow during glass forming, which may solidify as it is and adversely affect the quality of warp and the like. Therefore, when the purpose is to improve the strength and the quality of the warp, the film thickness is preferably 1 μm or more, 5 μm or more, 10 μm or more, 30 μm or more, 50 μm or more, or 60 μm or more. The thickness of the film-like glass can be adjusted by the flow rate of glass and the drawing speed.

Moreover, it is preferable that the average surface roughness Ra of the obtained film-like glass is 100 Å or less. In particular, it is desirable to be 50 mm or less, 10 mm or less, 8 mm or less, 4 mm or less, 3 mm or less, or 2 mm or less. If the average surface roughness Ra of the film-like glass is 100 mm or more, the display characteristics of the organic EL device may be deteriorated. On the other hand, when Ra is small, when the glass is pulled out from the roll, the glass-slip paper and the glass-glass may be continuously peeled off and the film surface may be charged. When such charging occurs, charging breakdown may occur in a later process, or fine particles in the atmosphere may be adsorbed on the surface of the film-like glass to cause a problem. In applications / processes in which such charging is regarded as important, it is preferable to set the Ra to 0.5 Å or more, 1 Å or more, 2 Å or more, 3 Å or more, 5 Å or more, 10 Å or more using atmospheric pressure plasma treatment or the like. The average surface roughness when the atmospheric pressure plasma treatment is used can be adjusted by, for example, the concentration of plasma gas (CF ₄ or O ₂ ).

  Moreover, it is preferable that the obtained glassy glass has a swell of 1 μm or less. In particular, it is desirable to be 0.08 μm or less, 0.05 μm or less, 0.03 μm or less, 0.02 μm or less, or 0.01 μm or less. If the waviness of the film-like glass is large, the display characteristics of the organic EL device may be deteriorated. The waviness of the film-like glass can be adjusted by the height of the stirring stirrer, the number of rotations, the temperature of the molded body, and the like.

  Moreover, it is preferable that the plate width of the film-like glass obtained is 500 mm or more. In an organic EL display, etc., after forming TFTs at once, so-called multi-sided cutting is performed for each panel, so that the cost per panel can be reduced as the film glass width increases. Become. The preferable plate width of the film-like glass is 600 mm or more, 800 mm or more, 1000 mm or more, 1200 mm or more, 1500 mm or more and 2000 mm or more. On the other hand, when it exceeds 3500 mm, it is difficult to ensure the thickness and surface quality in the plate width direction, and therefore it is preferably 3500 mm or less, 3200 mm or less, and 3000 mm or less. The plate width of the film-like glass can be adjusted by the size, shape, edge roller position and the like of the molded body. In addition, an edge roller is a roller installed in the uppermost stage, Comprising: It is a roller which controls a film width by giving the tension | tensile_strength of a horizontal direction, cooling the film-like glass which flowed down from the molded object.

  Further, the difference between the maximum plate thickness and the minimum plate thickness of the obtained film-like glass is preferably 20 μm or less, particularly preferably 10 μm or less, 5 μm or less, 2 μm or less, or 1 μm or less. In the downdraw method, when such a thickness deviation occurs at a certain position with respect to a certain plate width, when this difference becomes large, a part with a slightly different radius of curvature is slightly taken up when winding the film-like glass. Arise. If the amount of winding is increased, the product may be damaged by the stress caused by the difference in plate thickness, which is not preferable. In addition, the plate | board thickness difference (thickness deviation) of the maximum thickness of film-like glass and minimum thickness can be adjusted with the temperature in a slow cooling furnace.

  Further, the obtained film-like glass is heated from normal temperature at a rate of 10 ° C./min, held for 1 hour at a holding time of 500 ° C., and has a thermal shrinkage rate of 200 ppm or less, particularly when the temperature is lowered at a rate of 10 ° C./min. It is preferable that they are 150 ppm or less, 100 ppm or less, 80 ppm or less, 60 ppm or less, 50 ppm, 45 ppm, 40 ppm, 30 ppm or less, 20 ppm or less, 10 ppm or less. A thermal shrinkage rate of 200 ppm or more is not preferable because display defects such as pitch shift may occur in the thermal process for forming pixels in the organic EL display. The thermal shrinkage of the film-like glass can be reduced by optimizing the slow cooling conditions (slow cooling rate, slow cooling time, slow cooling temperature range, etc.).

  Further, the surface roughness Ra of the end face of the obtained film-like glass is preferably 100 mm or less, particularly 80 mm or less, 50 mm or less, 20 mm or less, 10 mm or less, 8 mm or less, or 6 mm or less. If it is 100 mm or more, the probability that the glass breaks from the end face increases, which is not preferable. In the case of laser cutting, the surface roughness Ra of the end surface of the film-like glass can be adjusted by the laser output and the cutting speed.

Further, the crack occurrence rate of the obtained film-like glass is preferably 70% or less, more preferably 50% or less, 40% or less, 30% or less, and particularly preferably 20% or less. In addition, the crack generation rate in this invention points out the value obtained by the following method. In this method, a Vickers indenter set at a load of 1000 g is driven into the glass surface (optical polishing surface) for 15 seconds in a constant temperature and humidity chamber maintained at a humidity of 30% and a temperature of 25 ° C. The number of cracks generated from the corner is counted (maximum 4 per indentation). This is a method in which this is repeated 20 times (that is, the indenter is driven 20 times), the total number of cracks is counted, and then the value obtained by the total number of cracks / 80 is obtained. Incidentally cracking of the film-like glass can be adjusted by the content of SiO _2, B ₂ O ₃ and an alkaline earth metal oxide.

When the glass constituting the obtained film-like glass is molded by adopting the overflow down draw method, the liquidus temperature of the glass is 1200 ° C. or lower, 1150 ° C. or lower, 1130 so that the glass is not devitrified during molding. The viscosity at the liquidus temperature is preferably 10 ^5.0 dPa · s or more, 10 ^5.6 dPa · s or more, 10 ^5.8 dPa. It is desirable that it is s or more, particularly 10 ^6.0 dPa · s or more.

  The glass constituting the film-like glass preferably has a Young's modulus of 65 GPa or more, 67 GPa or more, 68 GPa or more, 69 GPa or more, and most preferably 70 GPa or more.

Further, the glass constituting the film-like glass preferably has a density as low as possible in order to reduce the weight of the device. Specifically, it is 2.7 g / cm ³ or less, 2.6 g / cm ³ or less, 2.5 g. / Cm ³ or less, and particularly preferably 2.4 g / cm ³ or less.

The glass constituting the film-like glass has a coefficient of thermal expansion of 25 to 100 × 10 ⁻⁷ / ° C. in a temperature range of 30 to 380 ° C. so as to match the coefficient of thermal expansion of various films formed on the film-like glass. 30 to 90 × 10 ⁻⁷ / ° C., 30 to 60 × 10 ⁻⁷ / ° C., 30 to 45 × 10 ⁻⁷ / ° C., and 30 to 40 × 10 ⁻⁷ / ° C.

  The glass constituting the film-like glass preferably has a strain point, which is an index of heat resistance of the glass, of 600 ° C. or higher, particularly 630 ° C. or higher.

Glass satisfying various properties described above, for example, by mass _{percentage, SiO 2 40~80%, Al 2} O 3 0~20%, B 2 O 3 0~17%, 0~10% MgO, CaO 0~15 %, SrO 0-15% and BaO 0-30%. The reason for determining the composition range in this way will be described below.

The content of SiO ₂ is 40 to 80%. When the content of SiO ₂ increases, it becomes difficult to melt and mold the glass. Therefore, it is desirably 75% or less, preferably 64% or less, 62% or less, and particularly 61% or less. On the other hand, if the content is reduced, it becomes difficult to form a glass network structure and vitrification becomes difficult and the rate of occurrence of cracks increases or the acid resistance deteriorates, so 50% or more, preferably 55% or more, In particular, it is desirably 57% or more.

The content of Al ₂ O ₃ is 0 to 20%. When the content of Al ₂ O ₃ is increased, devitrified crystals are likely to precipitate on the glass and the liquid phase viscosity is lowered. Therefore, it is 20% or less, preferably 18% or less, 17.5% or less, particularly 17 % Or less is desirable. When the content of Al ₂ O ₃ decreases, the strain point of the glass decreases or the Young's modulus decreases, so that it is 3% or more, preferably 5% or more, 8.5% or more, 10% or more, 12%. As mentioned above, it is desirable that they are 13% or more, 13.5% or more, 14% or more, especially 14.5% or more.

B ₂ O ₃ is 0-17%. When the content of B ₂ O ₃ increases, the strain point decreases, the Young's modulus decreases, and the acid resistance deteriorates. Therefore, it is 17% or less, preferably 15% or less, 13% or less, 12% or less, It is desirable that it is 11% or less, particularly 10.4% or less. Further, when the content of B ₂ O ₃ is decreased, the high temperature viscosity is increased and the meltability is deteriorated, the crack generation rate is increased, the liquidus temperature is increased, and the density is increased. Above, preferably 3% or more, 4% or more, 5% or more, 7% or more, 8.5% or more, 8.8% or more, particularly 9% or more.

  MgO is a component that improves the Young's modulus and strain point of the glass and lowers the high-temperature viscosity, and has the effect of reducing the crack generation rate. However, if it is contained in a large amount, the liquidus temperature rises and the devitrification resistance decreases or the BHF resistance deteriorates, so 10% or less, 5% or less, 3% or less, 2% or less, 1.5% or less It is desirable to set it to 1% or less and 0.5% or less.

  The content of CaO is 0 to 15%. When the content of CaO is increased, the density and the thermal expansion coefficient are increased. Therefore, the content is desirably 15% or less, preferably 12% or less, 10% or less, 9% or less, or 8.5% or less. On the other hand, when the content of CaO decreases, the meltability deteriorates and the Young's modulus decreases. Therefore, it is preferably 2% or more, 3% or more, 5% or more, 6% or more, 7% or more, particularly 7. It is desirable to contain 5% or more.

  The content of SrO is 0 to 15%. When the SrO content is increased, the density and the coefficient of thermal expansion are increased. Therefore, it is desirably 15% or less, preferably 12% or less, 10% or less, 6% or less, 5% or less, particularly 6.5% or less. . On the other hand, if the content of SrO decreases, the meltability and chemical resistance deteriorate, so it is preferable to contain 0.5% or more, 1% or more, 2% or more, 3% or more, particularly 3.5% or more. .

  The content of BaO is 0 to 30%. Since the density and thermal expansion coefficient increase as the BaO content increases, it is 30% or less, preferably 25% or less, 20% or less, 15% or less, 10% or less, 5% or less, 2% or less, 1% or less. In particular, it is desirable that it is 0.5% or less.

  When each component of MgO, CaO, SrO, and BaO is mixed and contained, the liquidus temperature of the glass is remarkably lowered, and it is difficult to generate crystal foreign matters in the glass, thereby improving the meltability and formability of the glass. effective. However, if the total amount of these is small, the function as a flux is not sufficient and the meltability is deteriorated. Therefore, it is desirable to contain 5% or more, 8% or more, 9% or more, 11% or more, particularly 13% or more. . On the other hand, when the total amount of each component of MgO, CaO, SrO, BaO increases, the density increases, the weight of the glass cannot be reduced, and the crack generation rate tends to increase, so the total amount is 30% or less. 20% or less, 18% or less, particularly 15% or less is desirable. In particular, when it is desired to reduce the density of the film, the lower limit of the total amount is preferably 5% or more and 8% or more, and the upper limit is preferably 13% or less, 11% or less, and 10% or less.

  ZnO is a component that improves the meltability and increases the Young's modulus. However, if it is contained in a large amount, it tends to devitrify the glass, lowering the strain point and increasing the density, which is not preferable. Accordingly, the content is preferably 15% or less, 10% or less, 5% or less, 3% or less, 1% or less, and particularly preferably 0.5% or less.

ZrO ₂ is a component that improves the Young's modulus, but if it exceeds 5%, the liquidus temperature rises, and zircon devitrified foreign matter tends to be generated, which is not preferable. The preferable range of ZrO ₂ is 3% or less, more preferably 1% or less, still more preferably 0.5% or less, and most preferably 0.1% or less.

In addition to the above components, Y ₂ O ₃ , Nb ₂ O ₃ , and La ₂ O ₃ can be contained up to about 5% in the present invention. These components have a function of increasing the strain point, Young's modulus, etc., but if they are contained in a large amount, the density increases, which is not preferable.

Furthermore, in the above glass, 0 to 3% of one or two or more selected from the group of As ₂ O ₃ , Sb ₂ O ₃ , CeO ₂ , SnO ₂ , F, Cl, SO ₃ is used as a fining agent. Can do. However, As ₂ O ₃ , Sb ₂ O ₃ and F, especially As ₂ O ₃ and Sb ₂ O ₃ should be refrained from use as much as possible from an environmental point of view, and each content is less than 0.1%. Should be limited to Accordingly, preferred fining agents are SnO ₂ , SO ₃ and Cl. The SnO ₂ content is preferably 0 to 1%, 0.01 to 0.5%, particularly preferably 0.05 to 0.4%. The _SnO 2 + Cl + SO ₃ 0.001 to% 0.01-0.5%, which is 0.01 to 0.3%.

  Hereinafter, the present invention will be described based on examples. FIG. 1 shows an example of the manufacturing apparatus of the present invention. In the figure, 1 is an overflow downdraw molding device, 2 is a heat treatment furnace, 3 is a roller, 4 is an end separation device, 5 is a cutting device, 6 is a winding device, and G is a film glass.

  The overflow downdraw molding apparatus 1 includes a molded body having a wedge-shaped cross section having a groove at the top. Supply molten glass to the groove at the top of the molded body, overflow the molten glass from both sides to flow down both sides of the molded body, and draw out the molten glass in a film form by drawing out the glass flowing down at the lower end of the molded body Molded into glass G.

  Inside the heat treatment furnace 2, a molded body of the overflow downdraw molding apparatus 1 and a roller 3 for guiding the film-like glass G are installed, and substantially L-shaped so as to surround a path along which the film-like glass G moves. It extends in the mold, i.e. in the vertical and horizontal directions. The heat treatment furnace 2 has a structure capable of strictly controlling the temperature for each subdivided area, and functions as a slow cooling furnace below the compact. For this reason, the film-like glass G drawn continuously downward from the overflow downdraw apparatus 1 is drawn downward while being guided by the roller 3 inside the heat treatment furnace 2, and eventually its moving direction is changed from below to the horizontal direction. While being done, it is gradually cooled (temperature control) according to a predetermined schedule.

  The edge part separation apparatus 4 is equipped with the laser fusing equipment for irradiating a laser in parallel with the drawing direction and cutting off the film edge part (ear part). The cutting device 5 includes a scribe mechanism that can form a scribe line in a direction orthogonal to the moving direction of the film-like glass G, and a folding mechanism that folds the film with the formed scribe line. The film-like glass G that has passed through the slow cooling furnace 2 is cut off at the end portion of the film by the end portion separation device 4 and further cut by the cutting device 5 every predetermined length.

  The winding device 6 includes a winding mechanism that winds the film-like glass around the winding core, and a roll exchange mechanism that replaces the roll when a predetermined amount of winding is completed. When the film-like glass G is wound up by the winding device by a predetermined amount, the film-like glass G is cut by the cutting device 5 and the roll is cut off. Furthermore, the roll which has been wound up is taken out of the system, a new winding core is prepared, and winding of the film-like glass is resumed.

  An embodiment of the present invention using the above apparatus will be described.

First, a glass raw material was prepared so as to have the composition shown in Table 1, and supplied to a glass melting furnace (not shown) and melted at 1500 to 1600 ° C. Next, the molten glass was supplied to the overflow downdraw molding apparatus 1 and drawn downward to form a film-like glass G. In the molding, the glass supply amount and the drawing speed were adjusted so that the final film width was 1500 mm and the film thickness was 50 μm. Next, the film-like glass G was guided from the upper side to the lower side in the heat treatment furnace 2, and after changing the direction in the horizontal direction, it was guided to the outside of the heat treatment furnace 2. In this embodiment, the drawing speed and the heat treatment furnace 2 are set so that the cooling rate of the glass is 20 ° C./min in a region where the viscosity of the glass is a temperature corresponding to 10 ¹² to 10 ¹⁴ dPa · s. The temperature was adjusted. Subsequently, the film-shaped glass G that came out of the heat treatment furnace 2 was cut off by the edge separator 4 and then wound into a roll by the winder 6. Further, when the roll was fully wound, the film-like glass was cut by the cutting device 5.

  The film-like glass was drawn out from the roll thus obtained and cut into a predetermined size, and the amount of heat shrinkage, surface roughness, waviness, end surface roughness, and plate thickness difference were evaluated.

The thermal shrinkage was measured as follows. First, a 160 mm × 30 mm sample was cut out from a glass film (thickness 50 μm), and several strip-shaped test pieces were prepared. Marking was performed by pressing a # 1000 water-resistant abrasive paper against the glass in the vicinity of 20 mm to 40 mm from the end of the strip-shaped test piece (FIG. 2A), and the sheet was folded in a direction orthogonal to the marking. One of the folded test sides was heat-treated at 500 ° C. for 1 hour. The sample after the heat treatment was placed on a metal plate and rapidly cooled. A sample that had not been heat-treated and a sample that had been heat-treated were arranged side by side (FIG. 2B), and the amount of marking displacement (ΔL ₁ , ΔL ₂ ) was observed with a laser microscope. The thermal contraction rate at each temperature was calculated based on Equation 1.

  The average surface roughness (Ra) is a value measured by a method based on JIS B0601: 2001.

The surface roughness (Ra) of the end face is measured by a method according to JIS B0601: 2001 in the thickness direction of the plate and the direction perpendicular thereto, and the undulation using the average value is performed using a stylus type surface shape measuring device. It is a value obtained by measuring WCA (filtered center line waviness) described in JIS B-0610, and this measurement is performed by a method based on SEMI STD D15-1296 “Measurement method of surface waviness of FPD glass substrate”. The cut-off at the time of measurement is 0.8 to 8 mm, and is a value measured with a length of 300 mm in a direction perpendicular to the drawing direction of the glass substrate.

  The difference in plate thickness is determined by measuring the maximum and minimum plate thicknesses of the glass substrate by scanning the laser from one side of the film-like glass from the plate thickness direction using a laser-type thickness measuring device. This is a value obtained by subtracting the minimum thickness value from the thickness value.

  In addition, in order to evaluate various material properties, samples for evaluation were prepared by the following method. First, a glass raw material prepared to have the composition shown in the table was melted at 1600 ° C. for 24 hours in a platinum crucible. Subsequently, the molten glass was poured out on a carbon table, slowly cooled, processed into a predetermined size and shape, and subjected to the following evaluation.

  The density was measured by the well-known Archimedes method.

  The strain point was measured based on the method of ASTM C336-71. The higher this value, the higher the heat resistance of the glass.

  The softening point was measured based on the method of ASTM C338-93.

Viscosity ^{10 4.0,} 10 ^3.0, temperature at ¹⁰ 2.5 dPa · s were measured by a platinum ball pulling method. The lower this temperature, the better the meltability.

  The liquid phase temperature is measured by crushing the glass, passing through a standard sieve 30 mesh (500 μm), putting the glass powder remaining on 50 mesh (300 μm) into a platinum boat, holding it in a temperature gradient furnace for 24 hours, The temperature at which precipitation occurs is measured. The liquid phase viscosity indicates the viscosity of each glass at the liquid phase temperature. The higher the liquidus viscosity and the lower the liquidus temperature, the better the devitrification resistance and the moldability.

  The thermal expansion coefficient is obtained by measuring an average thermal expansion coefficient at 30 to 380 ° C. using a dilatometer. As a sample for measuring the thermal expansion coefficient, a glass plate was put in a platinum boat and remelted at 1400 ° C. to 1450 ° C. for 30 minutes to obtain a cylindrical sample of φ5 mm × 20 mm having an R-processed end face. The cylindrical sample was heated to 750 ° C. at + 5 ° C./min, held at the same temperature for 30 minutes, then cooled to 570 ° C. at −3 ° C./min, and from 570 ° C. to −10 ° C./min at room temperature. And the coefficient of thermal expansion was measured.

  The glass transition temperature was measured from the thermal expansion curve based on the method of JIS R3103-3.

The Young's modulus was measured by the resonance method. The crack occurrence rate was 15 seconds for a Vickers indenter set at a load of 1000 g on the glass surface (optical polished surface) in a constant temperature and humidity chamber maintained at 30% humidity and 25 ° C. The number of cracks generated from the four corners of the indentation is counted 15 seconds later (maximum of 4 per indentation). The indenter was driven 20 times, and the total number of cracks generated / 80 × 100 was evaluated.

  The BHF resistance and HCl resistance were evaluated by the following methods. First, after both surfaces of each glass sample were optically polished, they were immersed for a predetermined time at a predetermined temperature in a chemical liquid prepared to a predetermined concentration after partly masking. After the chemical treatment, the mask was removed, the step between the mask portion and the erosion portion was measured with a surface roughness meter, and the value was taken as the erosion amount. In addition, after optically polishing both surfaces of each glass sample, after immersing in a chemical solution prepared to a predetermined concentration for a predetermined time at a predetermined temperature, the glass surface is visually observed, and the glass surface becomes cloudy or rough Or those with cracks were marked with ×, and those without any change were marked with ○.

The chemical solution and the treatment conditions were measured for the BHF-resistant erosion amount using a 130 BHF solution (NH ₄ HF: 4.6% by mass, NH ₄ F: 36% by mass) at 20 ° C. for 30 minutes. Appearance evaluation was performed using a 63BHF solution (HF: 6% by mass, NH ₄ F: 30% by mass) under treatment conditions at 20 ° C. for 30 minutes. Further, the erosion resistance of HCl resistance was measured using a 10% by mass hydrochloric acid aqueous solution at 80 ° C. for 24 hours. Appearance evaluation was performed under a treatment condition of 80 ° C. for 3 hours using a 10 mass% hydrochloric acid aqueous solution.

  As is apparent from Table 1, the film-like glass produced by the method of the present invention has a low heat shrinkage ratio and a high Young's modulus, liquid phase viscosity, and strain point. Furthermore, the crack generation rate, density, and high temperature viscosity were low, and it was suitable as a glass film for display.

  The film-like glass produced by the method of the present invention is suitable as a substrate for flat panel displays such as liquid crystal displays and organic EL displays. Moreover, it can be used also for other uses, such as a glass substrate used for devices, such as a solar cell and a semiconductor, and a cover glass of organic EL lighting.

DESCRIPTION OF SYMBOLS 1 Overflow down draw molding apparatus 2 Heat processing furnace 3 Roller 4 End part separation apparatus 5 Cutting apparatus 6 Winding apparatus G Film-like glass

Claims (7)

  A method for producing a film-like glass, which is formed by forming a molten glass into a film by a downdraw method, slowly cooled, and then cut, characterized in that the moving direction of the film-like glass is changed to a horizontal direction during the slow cooling. A method for producing film-like glass.   The method for producing a film-like glass according to claim 1, wherein the film-like glass is molded so that the thickness is 100 μm or less.   The method for producing a film-like glass according to claim 1 or 2, wherein an overflow downdraw method is used as the downdraw method.   The method for producing a film-like glass according to any one of claims 1 to 3, wherein the film-like glass is wound up after being wound to form a roll.   Production of film-like glass comprising a down-draw molding device, a slow cooling furnace for gradually cooling the glass formed into a film shape by the down-draw molding device, and a cutting device for cutting the film-like glass that has passed through the slow cooling furnace into a predetermined length An apparatus for producing a film-like glass, wherein the moving direction of the film-like glass is changed from a vertical direction to a horizontal direction in an annealing furnace. 6. The apparatus for producing film-like glass according to claim 5 , wherein the downdraw molding apparatus is an overflow downdraw molding apparatus. Furthermore, the manufacturing apparatus of the film-form glass of Claim 5 or 6 provided with the winding-up apparatus which winds up film-form glass in roll shape.