JP5241223B2 - Glass plate manufacturing method and manufacturing equipment - Google Patents

Description

  The present invention relates to a method for manufacturing a glass plate and a manufacturing facility therefor, in which molten glass is caused to flow down from a molded body and a glass ribbon is stretch-formed in the vertical direction.

  As a method for manufacturing glass plates for flat panel displays such as various electronic devices, especially liquid crystal displays, downdrawing glass plates by pouring molten glass from the molded body and drawing glass ribbons in the vertical direction (vertical direction) The law is known.

  There are two types of downdraw methods: the overflow downdraw method and the slot downdraw method. In particular, the overflow downdraw method has a very small surface waviness and roughness and provides a glass plate with excellent surface quality. Is known as a method that can.

  In the overflow down draw method, molten glass continuously supplied to the top of a molded body having a wedge-shaped cross-sectional shape is caused to flow down from the top of the molded body along both side surfaces, and is fused at the lower end of the molded body. Thus, a plate-like glass ribbon is formed, and both edge portions of the glass ribbon are stretched and formed into a glass ribbon by flowing down a conveying path extending in the vertical direction while being sandwiched by a plurality of pulling rollers. As a result, the glass ribbon gradually solidifies and becomes a glass plate having a predetermined width and thickness. Moreover, the atmospheric temperature of the conveyance path is strictly controlled, and thereby the thermal distortion of the glass plate is sufficiently removed, and then the glass sheet is cooled to around room temperature.

  In this case, since the pulling roller usually holds only both edges of the glass ribbon, if the slight holding part (the part deviating from the effective surface that becomes a glass product) is excluded, anything It becomes possible to shape | mold the glass plate with the surface which is not touched, and, thereby, the glass plate excellent in the surface quality is obtained. Therefore, according to this molding method, there is an advantage that a polishing step that causes high cost is unnecessary.

In the downdraw method, the pulling roller for drawing the glass ribbon downward needs to sandwich both edges of the glass ribbon that is still in a high temperature state, so it must withstand a temperature of about 800 ° C. Is made of an inorganic material containing ceramic fibers and a binder (see, for example, Patent Documents 1 and 2).
JP 2006-69825 A JP 2005-520774 A

  In recent years, glass plates for flat panel displays have been increased in size, and for example, glass ribbons having a width dimension (effective width) of 2000 mm or more at a part finally becoming a glass product have been formed. Yes. However, when the width dimension of the glass ribbon is increased, the weight of the glass ribbon is increased, and the phenomenon that the molten glass near the formed body is pulled by its own weight and dropped may occur. For this reason, the pulling roller has a role of preventing the glass ribbon from dropping due to its own weight and adjusting its flow speed (plate drawing speed), in addition to the conventional role of stretching the glass ribbon in the vertical direction. Yes.

  However, since the pulling roller is made of an inorganic material as described above, slip easily occurs between the pulling roller and the glass ribbon, and the role of adjusting the flow rate of the glass ribbon cannot be sufficiently fulfilled. That is, if slip occurs between the glass ribbon and the pulling roller, the drawing speed of the glass ribbon becomes unstable, resulting in a variation in the thickness of the glass ribbon and a decrease in yield. Further, when slip occurs, there are problems that scratches are formed on the surface of the glass ribbon and the glass ribbon is broken.

  As a method of preventing the slip that occurs between the glass ribbon and the pulling roller, it may be possible to increase the contact pressure of the pulling roller against the glass ribbon. However, if the contact pressure is increased more than necessary, there is no use in the glass ribbon. There is a risk of causing internal stress and damaging the glass ribbon. In addition, a part of the surface of the holding portion of the pulling roller may be peeled off, and it may adhere to the glass ribbon, resulting in a surface defect of the glass plate.

  The present invention has been made in view of the above circumstances, avoiding problems such as surface defects, breakage, etc. accompanying the increase in the size of glass plates, problems of yield reduction, etc., and producing high-quality glass plates with high productivity. It is a technical problem to provide a method for obtaining the above.

The method for producing a glass plate of the present invention comprises a molding step of supplying molten glass to a molded body and flowing the molten glass from the molded body to a conveying path extending in a vertical direction to draw and form a glass ribbon. In the manufacturing method of a glass plate including an annealing step for removing thermal distortion of the glass ribbon, and a cooling step for cooling the glass ribbon to near room temperature, an effective width of the glass ribbon is 2000 mm or more, and the molding step includes: A step of forming a glass ribbon by an overflow down draw method or a slot down draw method, and in the annealing step, a pulling roller made of an inorganic material pulls the both ends of the glass ribbon in the width direction while pulling downward, in the cooling step, and sandwiched by support rollers formed by forming the edges of the glass ribbon from a synthetic rubber, Characterized in that it causes later.

According to the method for producing a glass plate of the present invention, after removing the thermal strain by slowly cooling the glass ribbon formed in the forming step in the annealing step set to a predetermined temperature gradient, Since both edges of the ribbon are sandwiched between the support rollers, the weight of the glass ribbon increases, and even if the flow speed is likely to change due to its own weight, slip between the glass ribbon and the pulling roller can be prevented. . In particular, when obtaining a glass plate excellent in surface quality, it is desirable to adopt the overflow down draw method rather than the slot down draw method. The slot down draw method is a method of drawing a molten glass from a long hole (slot shape) opening formed in a part of a heat resistant metal (molded body) into a plate-like glass ribbon. This is a method of producing a glass plate by stretching in the vertical direction. The slip between the glass ribbon and the pulling roller appears prominently when the effective width of the glass ribbon (glass plate) is 2000 mm or more and the weight increases, so the slip prevention effect by the support roller is increased. Therefore, the present invention is more useful when the effective width of the glass ribbon is 2500 mm or more, and further 3000 mm or more. Synthetic rubber has an advantage that it is easy to adjust the physical properties such as hardness, flexibility, and surface smoothness, so that it is easy to obtain a material that can securely hold the glass ribbon. Therefore, when the support roller is made of synthetic rubber, slip between the glass ribbon and the pulling roller is surely prevented, and the flow rate of the glass ribbon can be easily controlled.

  The glass plate manufacturing method of the present invention is characterized in that the support roller is formed of a synthetic rubber having a coefficient of static friction with glass of 1.00 or more.

  That is, when the support roller is made of synthetic rubber having a static friction coefficient with glass of 1.00 or more, the glass ribbon can be securely held even if the contact pressure between the support roller and the glass ribbon is reduced. Therefore, the problem that internal stress more than necessary occurs in the glass ribbon can be avoided as much as possible. The coefficient of static friction of the synthetic rubber is preferably 1.20 or more, more preferably 1.40 or more. Here, the coefficient of static friction is a well-known inclination measurement method, that is, at room temperature, with the flat portion of the support roller material placed on the glass plate, the glass plate is gradually inclined, and the support roller material begins to move. When the angle was θ, measurement was performed by a method in which tan θ was a static friction coefficient.

  The glass plate production method of the present invention is characterized in that the support roller is formed from a synthetic rubber having a heat resistant temperature of 200 ° C. or higher.

  In the present invention, the support roller is installed in the cooling process, but it is preferable to attach the support roller as close to the upper part of the cooling process as possible, that is, a position close to the annealing process, because the effect of supporting the glass ribbon is great. However, since the temperature of the glass ribbon immediately after the annealing process is higher than 200 ° C., a synthetic rubber having a low heat resistance temperature such as nitrile rubber, acrylic rubber, urethane rubber, ethylene propylene rubber, butyl rubber, epichlorohydrin rubber Such synthetic rubber may cause thermal deformation. For this reason, when using a synthetic rubber having a low heat-resistant temperature, there is a restriction that a cooling mechanism for a portion in contact with the glass ribbon is necessary so as not to be thermally deformed, or that the high-temperature portion of the glass ribbon is avoided. However, when a synthetic rubber having a heat resistant temperature of 200 ° C. or higher is used, a cooling mechanism is unnecessary, and thermal deformation does not occur even when the high temperature portion of the glass ribbon is sandwiched. Here, the heat resistant temperature means a maximum temperature at which the physical properties from room temperature can be maintained without causing the synthetic rubber to be deformed by heat or causing stickiness. The heat resistant temperature of the synthetic rubber used is preferably 250 ° C. or higher, more preferably 270 ° C. or higher, and further preferably 300 ° C. or higher. As the synthetic rubber used in the present invention, silicone rubber and fluororubber are suitable. Since these synthetic rubbers have a high coefficient of static friction with glass and a heat-resistant temperature of 200 ° C. or higher, it is possible to maintain physical properties such as a coefficient of static friction even in a high temperature atmosphere.

  In the present invention, the high temperature portion of the glass ribbon in the cooling step (for example, a portion of 200 ° C. or higher) is sandwiched between support rollers made of synthetic rubber having a heat resistant temperature of 200 ° C. or higher, and the low temperature portion of the glass ribbon (for example, 200 The portion having a heat resistant temperature of less than 200 ° C. may be sandwiched between support rollers made of synthetic rubber.

  Moreover, the manufacturing method of the glass plate of this invention arrange | positions several pairs (for example, 3-10 pairs) of support rollers to the orthogonal | vertical direction (up-down direction), and clamps the both edges of a glass ribbon with each support roller, It is characterized by the above-mentioned. And

  In the present invention, if a plurality of pairs of support rollers are arranged in the vertical direction, the load per support roller can be reduced even when the weight of the glass ribbon increases, so the drive unit of each support roller is designed to be compact. be able to. Moreover, since the physical properties required for the support roller are alleviated, the range of materials that can be used for the support roller is widened.

  In addition, since the thickness of a glass ribbon etc. will become non-uniform | heterogenous if the glass ribbon shape | molded by the down draw method is not supported uniformly, it is necessary to rotate a support roller on either side synchronously. For this reason, it is preferable that the left and right support rollers are attached to a single roller shaft because each support roller rotates in synchronization. Even when the left and right support rollers are provided independently (separated), the glass ribbon can be uniformly supported by providing a mechanism for rotating them in synchronization with an electric circuit.

  Further, the present invention is characterized in that three or more support rollers are separately attached to one roller shaft, and both edge portions and intermediate portions of the glass ribbon are sandwiched.

  In the present invention, in addition to the two support rollers that sandwich both edges of the glass ribbon, it is possible to attach another support roller between the support rollers. For example, if both edges and the center of the glass ribbon are sandwiched between three support rollers, the contact area between the glass ribbon and the support roller increases, and the glass ribbon can be sandwiched even with a smaller contact pressure. it can. Therefore, for example, even when a large glass ribbon having a width of 3000 mm or more is formed, the glass ribbon can be stably supported. Moreover, it is also possible to attach a plurality of support rollers for sandwiching the intermediate portion of the glass ribbon (portions other than both edge portions). When a plurality of pairs of support rollers are arranged in the vertical direction, a support roller that sandwiches both edge portions and the intermediate portion of the glass ribbon may be attached to only a part of the roller shafts. However, since the portion of the glass ribbon surface sandwiched between the support rollers is likely to be contaminated, it is desirable to cut and remove the portion in a subsequent process.

  Moreover, the manufacturing method of the glass plate of this invention is characterized by including the cutting process which makes a glass ribbon flow down to a perpendicular direction further after a cooling process, and cut | disconnects to a predetermined dimension.

  That is, in the present invention, in the cutting step, it is possible to cut the glass ribbon flowing down from the cooling chamber in the vertical direction and move it in the horizontal direction, but when the glass ribbon becomes thin, it breaks during bending. Or the equipment tends to be complicated. Therefore, it is preferable to let the glass ribbon flow down from the cooling chamber in the vertical direction and cut in the horizontal direction (direction perpendicular to the moving direction) so as to have a predetermined size.

The glass plate production facility of the present invention is a molding furnace for supplying molten glass to a molded body and for drawing the molten glass from the molded body to a conveying path extending in the vertical direction and drawing it into a sheet-like glass ribbon. , An annealing furnace for removing thermal distortion of the glass ribbon, and a glass plate manufacturing facility comprising a cooling chamber for cooling the glass ribbon to near room temperature, wherein the effective width of the glass ribbon is 2000 mm or more In the molding furnace, a molded body for performing stretch molding of the glass ribbon by an overflow down draw method or a slot down draw method is disposed, and both end portions of the glass ribbon are disposed in the annealing furnace. tensile roller made of an inorganic material pulling in the widthwise direction are arranged, the said cooling chamber, clamping the edges of the glass ribbon, synthetic rubber for lowering Formed from comprising support rollers, characterized in that is disposed.

  According to the glass plate manufacturing facility of the present invention, after removing the thermal strain by slowly cooling the glass ribbon formed in the forming furnace in the annealing furnace set to a predetermined temperature gradient, Since both edges of the ribbon are sandwiched between the support rollers, the weight of the glass ribbon becomes large, and even if it becomes easy to flow down due to its own weight, slip between the glass ribbon and the pulling roller can be prevented.

  The glass plate manufacturing facility of the present invention is characterized in that a cutting chamber for cutting a glass ribbon into a predetermined length is provided immediately below the cooling chamber.

  That is, in the present invention, in the cutting step, it is possible to cut the glass ribbon flowing down from the cooling chamber in the vertical direction and move it in the horizontal direction, but when the glass ribbon becomes thin, it breaks during bending. Or the equipment tends to be complicated. Therefore, it is preferable to provide a cutting chamber immediately below the cooling chamber and cut the glass ribbon flowing down in the vertical direction in the horizontal direction so as to have a predetermined dimension.

  As described above, according to the present invention, even when the weight of the glass ribbon is large, both edges are sandwiched by the support roller, so that no slip occurs between the glass ribbon and the pulling roller, and the down draw method is used. The production of the glass plate can be performed stably.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic front view showing equipment for manufacturing a glass plate of the present invention, FIG. 2 is a schematic side view of FIG. 1, and FIG. 3 is an enlarged perspective view of a support roller. This manufacturing equipment is for manufacturing a glass plate (glass substrate) for a liquid crystal display by the overflow down draw method, and is supplied from the top to the molten glass 10 having a wedge-shaped cross-sectional shape. By overflowing A from the top and fusing at the lower end thereof, a forming furnace 11 for forming the glass ribbon B, an annealing furnace 12 for removing the thermal strain while gradually cooling the glass ribbon B, and A cooling chamber 13 that sufficiently cools the cooled glass ribbon B and a cutting chamber 14 that cuts the cooled glass ribbon B into a predetermined dimension are provided. The forming furnace 11 and the annealing furnace 12 are closed in a state surrounded by the furnace wall 15, and a conveyance path 16 through which the glass ribbon B flows down is formed between the forming furnace 11, the annealing furnace 12, the cooling chamber 13, and the cutting chamber 14. Communicate. The cutting chamber 14 is additionally provided with a transport path for transporting the glass plate C to a subsequent process (for example, an end surface polishing process) that is not shown.

  Next, the manufacturing process of the glass plate by the said glass plate manufacturing equipment is demonstrated.

  In this manufacturing facility, first, molten glass A is supplied to the top of the molded body 10 provided in the molding furnace 11, and the molten glass A overflows from the top of the molded body 10 and is fused at the lower end thereof. A shaped glass ribbon B is formed. A pair of cooling rollers (edge rollers) 17 is provided in the vicinity of the molded body 10, and both edges of the glass ribbon B are held between the cooling rollers 17, and shrinkage in the width direction is minimized.

  Next, the formed glass ribbon B is gradually cooled in the annealing furnace 12 to remove thermal strain. In the annealing furnace 12, a plurality of pairs of pulling rollers (annealing rollers) 18 are arranged in the vertical direction, and pulled downward while pulling in the width direction by the pulling roller 18 so that the glass ribbon B does not contract in the width direction due to surface tension or the like. To do. Further, the inside of the annealing furnace 12 is set to have a predetermined temperature gradient by a heater, and the glass ribbon B gradually decreases in temperature as it flows down in the annealing furnace 12, so that the thermal strain generated therein is reduced. Removed. The pulling roller 18 in the annealing furnace 12 is made of an inorganic material containing ceramic fibers and a binder. What is necessary is just to adjust the circumferential speed of the tension | pulling roller 18 with the flow volume of a molten glass, the dimension of the glass ribbon B, etc., for example, it sets so that it may become 200-500 cm / min.

  A cooling chamber 13 is provided below the annealing furnace 12. A plurality of pairs of support rollers 19 are arranged in the cooling chamber 13 and are lowered while sandwiching both edges of the glass ribbon B solidified to a predetermined size. The glass ribbon B is cooled to approximately room temperature in the cooling chamber 13. As for the support roller 19 arrange | positioned in the cooling chamber 13, the surface layer is produced from silicone rubber (heat-resistant temperature 300 degreeC or more, a static friction coefficient with a glass plate 1.40 or more), and through the core part 19a which consists of rolled steel materials, A roller shaft (shaft) 20 made of carbon steel is attached. The peripheral speed of the support roller 19 may be adjusted as appropriate, and is set to 200 to 500 cm / min, for example.

  A cutting chamber 14 is provided immediately below the cooling chamber 13. The glass ribbon cooled to near room temperature in the cooling chamber 14 is cut into a glass plate C having a predetermined size in the cutting chamber 14 and then conveyed to a subsequent process.

Using the above glass plate manufacturing equipment, by mass%, SiO ₂ 60%, Al ₂ O ₃ 15%, B ₂ O ₃ 10%, CaO 6%, SrO 6%, BaO 2%, refining agent 1 %, A glass plate for liquid crystal display (OA-10 manufactured by Nippon Electric Glass Co., Ltd.) having an effective width of 2000 mm and a thickness of 0.7 mm was molded. However, since both ends of the glass ribbon B require a tension allowance called an ear portion to be pulled by the pulling roller 18, the total width of the glass ribbon B is designed to be about 2300 mm.

  Since this glass plate C has a large width dimension, the weight of the glass ribbon B also increases, but no slip was observed between the glass ribbon B and the pulling roller 18. Therefore, the drawing speed of the glass ribbon B was stable, and the obtained glass plate C had an effective width of 2000 mm or more within a thickness range of 0.7 mm ± 0.05 mm, and there was no surface damage or breakage.

  FIG. 4 is a schematic front view showing a glass plate manufacturing facility according to another embodiment of the present invention. In this cooling facility 13, the cooling chamber 13 is configured to sandwich the three edges of the glass ribbon B at the two edges and the intermediate portion by the support roller 19 attached to the two roller shafts disposed at the lower stage. The other configuration is the same as that of the manufacturing equipment of FIGS.

  Using this glass plate manufacturing equipment, a glass plate for liquid crystal display (OA-10, manufactured by Nippon Electric Glass Co., Ltd.) having an effective width of 2500 mm and a thickness of 0.7 mm was formed. No slip was observed between the inner pulling roller 18 and the inner pulling roller 18. Therefore, the drawing speed of the glass ribbon B is stable, and the glass plate C after being cut into the glass plate C having a predetermined size in the cutting chamber 14 has an effective width of 2500 mm within a range of 0.7 mm ± 0.05 mm. There were no surface scratches or damage.

  In addition, this invention is not limited to said embodiment, In the range which does not deviate from the summary of this invention, it can implement with a various form further.

  For example, in the above embodiment, the case where the present invention is applied to the production of a glass plate by the overflow downdraw method has been described. However, the present invention is similarly applied to the production of a glass plate by, for example, the slot downdraw method. The invention can be applied.

  The glass plate manufacturing method and manufacturing equipment of the present invention includes a glass plate used for various flat panel displays such as a liquid crystal display glass plate, an electroluminescence display such as a plasma display, an organic EL, a field emission display, and the like. It can use for manufacture of the glass plate used as a base material for forming an electronic display functional element and a thin film.

It is a schematic front view which shows the manufacturing equipment of the glass plate of this invention. It is a schematic side view which shows the manufacturing equipment of the glass plate of this invention. It is an expansion perspective view of the support roller used by this invention. It is a schematic front view which shows the manufacturing equipment of the glass plate which concerns on the other form of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Molded object 11 Molding furnace 12 Annealing furnace 13 Cooling chamber 14 Cutting chamber 15 Furnace wall 16 Conveyance path 17 Cooling roller (edge roller)
18 Pulling roller (annealing roller)
19 Support roller 19a Support roller core 20 Roller shaft (shaft)
A Molten glass B Glass ribbon C Glass plate

Claims (8)

A molding process of supplying molten glass to a molded body and flowing the molten glass from the molded body to a conveying path extending in a vertical direction to draw and form it into a plate-shaped glass ribbon, and an annealing process of removing thermal distortion of the glass ribbon , A cooling step of cooling the glass ribbon to near room temperature,
The effective width of the glass ribbon is 2000 mm or more,
The forming step is a step of forming a glass ribbon by an overflow down draw method or a slot down draw method,
In the annealing step, a pulling roller made of an inorganic material pulls the both ends of the glass ribbon while pulling in the width direction.
In the cooling step, a method for producing a glass plate, wherein both edges of the glass ribbon are sandwiched and lowered by a support roller formed of synthetic rubber . The method for producing a glass plate according to claim 1 , wherein the support roller is formed of a synthetic rubber having a coefficient of static friction with glass of 1.00 or more. Supporting rollers, manufacturing method for a glass plate according to any one of claims 1-2 in which the heat temperature is characterized by comprising formed from 200 ° C. or more synthetic rubbers.   The method for producing a glass plate according to any one of claims 1 to 3, wherein a plurality of pairs of support rollers are arranged in the vertical direction, and both edges of the glass ribbon are sandwiched between the support rollers. The glass plate according to any one of claims 1 to 4 , wherein three or more support rollers are attached to one roller shaft at a distance, and both edge portions and an intermediate portion of the glass ribbon are sandwiched. Production method. The method for producing a glass plate according to any one of claims 1 to 5 , further comprising a cutting step of causing the glass ribbon to flow down in the vertical direction and cutting the glass ribbon into a predetermined dimension after the cooling step. While supplying molten glass to a molded object, the molten glass is made to flow down to the conveyance path extended in the orthogonal | vertical direction from the molded object, and the shaping furnace for extending | stretch-forming to a plate-shaped glass ribbon, The thermal distortion of this glass ribbon is removed. An annealing furnace for cooling the glass ribbon, and a cooling chamber for cooling the glass ribbon to near room temperature.
The effective width of the glass ribbon is 2000 mm or more,
In the molding furnace, a molded body for performing stretch molding of the glass ribbon by the overflow down draw method or the slot down draw method is disposed,
In the annealing furnace, a pulling roller made of an inorganic material that pulls both ends of the glass ribbon in the width direction is disposed,
An apparatus for manufacturing a glass plate, wherein the cooling chamber is provided with a support roller made of synthetic rubber for sandwiching and lowering both edges of the glass ribbon. 8. The glass plate manufacturing equipment according to claim 7 , further comprising a cutting chamber for cutting the glass ribbon into a predetermined length immediately below the cooling chamber.

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