JP2019026489A - Method and apparatus for manufacturing glass article - Google Patents

Abstract

To control the viscosity of molten glass while preventing the molten glass from devitrifying.SOLUTION: A method for manufacturing a glass article comprises a forming step of dropping molten glass GM along the surface of a molding 4 to form a glass article GR. The molding 4 includes a first portion 4a on the upstream side and a second portion 4b on the downstream side. The first portion 4a is arranged in a first space S1 in which the molten glass GM dropped on the first portion 4a is heated at a temperature higher than a liquid phase temperature, and the second portion 4b is arranged in a second space S2 in which the molten glass GM passing the first portion 4a and dropped on the second portion 4b is cooled at a temperature lower than the liquid phase temperature.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method and apparatus for producing glass articles by forming molten glass.

  As is well known, there are surface defects and undulations in plate glass used in various fields, as represented by glass substrates for flat panel displays (FPD) such as liquid crystal displays (LCDs) and organic EL displays (OLEDs). In fact, strict product quality is required.

  In order to satisfy such a requirement, the overflow downdraw method is widely used as a method for producing a plate glass. In the overflow down draw method, molten glass is poured into an overflow groove provided on the upper part of a substantially wedge-shaped cross section, and the molten glass overflowing on both sides from the overflow groove is formed along the side wall portions on both sides of the molded body. While flowing down, they are fused and integrated at the lower end of the molded body, and a single sheet of glass is continuously formed.

  As disclosed in Patent Document 1, an apparatus for producing a glass article using an overflow downdraw method is provided with a molding furnace having a molded body therein, a slow cooling furnace installed below the molding furnace, and a lower cooling furnace. Some have a cooling part and a cutting part. In order to manufacture a glass article with this manufacturing apparatus, first, molten glass is allowed to overflow from the top of the molded body and is fused at the lower end of the molded body to form a plate glass (glass ribbon). Furthermore, the edge part of this plate glass is hold | gripped with an edge roller (cooling roller), and it is made to pass through a slow cooling furnace, and the internal distortion is removed. Then, after cooling plate glass to room temperature in a cooling part, it cut | disconnects to a predetermined dimension in a cutting part.

JP 2012-197185 A

  In the conventional manufacturing method and manufacturing apparatus, in order to hold the plate glass fused at the lower end of the molded body with the edge roller, the molten glass needs to have a viscosity of 300 Pa · s or more. Depending on the composition of the glass article to be molded, the molten glass may not reach the above viscosity during fusion. In order to form such a glass article by the overflow down draw method, it is conceivable to cool the molten glass so as to obtain a moldable viscosity at the time of fusion by the formed body.

  However, when the temperature of the cooled molten glass becomes a liquid phase temperature and a certain time elapses, the glass may be devitrified.

  This invention is made | formed in view of said situation, and it aims at providing the manufacturing method of the glass article which can adjust the viscosity of a molten glass, preventing devitrification.

  The present invention is for solving the above-mentioned problem, and in a method for manufacturing a glass article comprising a molding step of forming a glass article by causing molten glass to flow down along the surface of the molded article, A first portion on the side and a second portion on the downstream side, wherein the first portion heats the molten glass flowing down the first portion to a temperature higher than a liquidus temperature. Arranged in one space, the second part is arranged in a second space that cools the molten glass passing through the first part and flowing down the second part to a temperature lower than the liquidus temperature. It is characterized by being.

  According to this method, since the molten glass flowing down the molded body is heated to a temperature higher than the liquidus temperature in the first space, it flows from the first part to the second part without causing devitrification. . Since the molten glass flowing down the second portion is rapidly cooled to a temperature lower than the liquid phase temperature by the second space, devitrification can be suitably suppressed. By being cooled in this way, the molten glass is adjusted to a viscosity suitable for molding in a state where devitrification is prevented.

  In the present method, it is desirable that the second portion includes a metal on the surface or inside thereof, and in the forming step, the metal is heated by electromagnetic induction. The flow rate of the molten glass flowing down the molded body is remarkably reduced at the interface with the molded body. In the present invention, the interface of the molten glass can be heated by causing the metal provided in the second portion to generate heat by electromagnetic induction. Thereby, the interface of a molten glass can be heated so that it may become higher than liquid phase temperature, and the devitrification of the said interface can be prevented.

  Not limited to the above, the second part may have a heating element inside, and in the molding step, the second part may be heated by the heating element. Thereby, the interface of a molten glass can be heated so that it may become high temperature rather than liquidus temperature.

  In this method, it is preferable that the second portion is provided at a lower portion of the molded body with a length of 10% to 50% with respect to the total height of the molded body.

  The first space and the second space are preferably separated by a partition wall. Thereby, the temperature management of the first space and the second space can be performed with high accuracy. In this case, the partition preferably includes ceramic.

  The molding step preferably includes a step of cooling the second space. By cooling the second space, the molten glass passing through the second space through the second portion can be effectively cooled.

  In the present method, it is desirable that the forming step forms the glass sheet by an overflow down draw method.

The glass article manufactured in this method may be composed of a phosphate-based glass containing 25% or more of P ₂ O ₅ by mass% as a composition.

  The present invention is for solving the above-described problem, and is a glass article manufacturing apparatus including a molded body that causes molten glass to flow down along the surface, the molded body including an upstream first portion and A second portion on the downstream side, a first space in a high-temperature atmosphere in which the first portion on the upstream side of the molded body is disposed, and a second portion on the downstream side of the molded body is disposed. And a second space having a low temperature atmosphere.

  According to the manufacturing apparatus having the above-described configuration, the molten glass flowing down the molded body is heated to a temperature higher than the liquid phase temperature in the first space. It flows to. Since the molten glass flowing down the second portion is cooled to a temperature lower than the liquidus temperature by the second space, devitrification can be suitably suppressed. By being cooled in this way, the molten glass is adjusted to a viscosity suitable for molding in a state where devitrification is prevented.

  According to the present invention, it is possible to adjust the viscosity of molten glass while preventing devitrification.

It is front sectional drawing which shows the manufacturing apparatus of the glass article which concerns on 1st embodiment. It is the II-II sectional view taken on the line of FIG. It is an expanded sectional view of a molded object. It is an expanded sectional view which shows the lower end part periphery of a molded object. It is side surface sectional drawing which shows the manufacturing apparatus of the glass article which concerns on 2nd embodiment. It is side surface sectional drawing which shows the manufacturing apparatus of the glass article which concerns on 3rd embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 thru | or FIG. 4 shows one Embodiment of the manufacturing method and manufacturing apparatus of the glass article which concern on this invention.

  As shown in FIGS. 1 and 2, the manufacturing apparatus 1 includes a forming furnace 2 and a slow cooling furnace 3. The molding furnace 2 draws out a molded body 4 capable of executing the overflow downdraw method, a furnace wall 5 covering the molded body 4, a cooling unit 6 disposed below the molded body 4, and the molten glass GM as a plate glass GR. An edge roller 7.

  The molded body 4 is formed in an elongated shape, and includes an overflow groove 8 formed along the longitudinal direction, and a vertical surface portion 9 and an inclined surface portion 10 that form a pair of side wall portions. The molded body 4 causes the molten glass GM overflowing from the overflow groove 8 to flow down along the pair of side wall portions and fuse at the lower end portion 11 thereof. In addition, a pair of inclined surface part 10 cross | intersects by approaching gradually below, and this intersection part comprises the lower end part 11 of the molded object 4. FIG.

  The molded body 4 includes a molded body main body 12 and a metal film 13 that covers the molded body main body 12. The molded body 12 is composed of a refractory material such as electroformed brick or dense zircon. The metal film 13 covers the entire outer surface of the molded body 12. The metal film 13 is made of a noble metal such as platinum or a platinum alloy. In addition, as a platinum alloy, a platinum-rhodium alloy, a platinum-iridium alloy, a platinum-gold alloy etc. can be used, for example. Although the thickness of the metal film 13 is 0.5 mm or more and 1.5 mm or less, it is not limited to this range.

  As shown in FIGS. 1 to 3, the molded body 4 includes an upper (upstream) first portion 4 a and a lower (downstream) second portion 4 b. The first part 4 a is a part located inside the furnace wall 5 of the molding furnace 2, and the second part 4 b is a part located in the cooling unit 6. The length Ha (see FIG. 3) in the vertical direction of the second portion 4b is desirably set to 10% to 50% of the total length (total height) H of the molded body 4 in the vertical direction.

  The furnace wall 5 is comprised with refractories, such as an electroformed brick and dense zircon. The outer surface of the furnace wall 5 is covered with a metal casing (not shown). Inside the furnace wall 5, a space (hereinafter referred to as “first space”) S <b> 1 that can accommodate the molded body 4 is formed. The 1st part 4a of the molded object 4 is arrange | positioned in 1st space S1. Moreover, the heater 14 which heats the molten glass GM which flows down the molded object 4 is arrange | positioned in 1st space S1. By the heating of the heater 14, the atmospheric temperature in the first space S <b> 1 is adjusted to be higher than the liquidus temperature of the plate glass GR, for example, 750 ° C. to 1100 ° C.

  The cooling unit 6 includes a space (hereinafter referred to as “second space”) S <b> 2 that accommodates the second portion 4 b of the molded body 4. The second space S <b> 2 is partitioned by the side wall portion 15, the first partition wall 16, and the second partition wall 17. A device (heating device) 18 for heating the second portion 4b of the molded body 4 is disposed in the second space S2. A device (cooling device) 19 for cooling the second space S2 is disposed outside the second space S2.

  The second portion 4b of the molded body 4 is disposed in the second space S2. That is, the second space S <b> 2 is a space for cooling the molten glass GM transmitted through the inclined surface portion 10 of the second portion 4 b of the molded body 4. The atmospheric temperature of the second space S2 is adjusted to 25 ° C. or more and 200 ° C. or less by the cooling device 19. The atmospheric temperature of the second space S2 is set to be 500 ° C. or more lower than the liquidus temperature of the molten glass GM. For example, it is desirable that the temperature of the second space S2 is set to room temperature. In this specification, normal temperature means 0 degreeC or more and 40 degrees C or less.

  The side wall part 15 is comprised with refractories, such as a metal, an electroformed brick, a dense zircon. The side wall portion 15 is configured in a cylindrical shape so as to surround the entire circumference of the second portion 4 b of the molded body 4. The side wall 15 partitions the second space S <b> 2 together with the first partition wall 16 and the second partition wall 17.

  The 1st partition 16 is a horizontal wall part which divides 1st space S1 and 2nd space S2. The first partition 16 has an opening 20 through which the second portion 4 b of the molded body 4 can be inserted. The first partition 16 is configured to be movable in the horizontal direction, whereby the size of the opening 20 can be adjusted. The 1st partition 16 is comprised by plate shape with ceramics, such as a cordierite and an alumina. In the first partition 16, a portion located in the vicinity of the heating device 18 may be made of ceramic, and the other portion may be made of metal.

  The second partition wall 17 is a horizontal wall part for separating the second space S2 and the slow cooling furnace 3. The second partition wall 17 is formed in a plate shape from metal or ceramic. The second partition wall 17 has an opening 21 through which the plate glass GR formed by fusion molding with the molded body 4 passes. Similar to the first partition wall 16, the second partition wall 17 can be configured to be movable in the horizontal direction.

  The cooling device 19 includes a suction device such as a pump and a fan. The cooling device 19 is disposed outside the second space S2 (outside the side wall 15) and is connected to the second space S2 through a pipe. The cooling device 19 is not limited to this configuration, and may be configured by a device (air supply device) capable of supplying air for cooling to the second space S2, or a pipe is installed in the second space S2. The refrigerant (gas or liquid) may be circulated through the pipe.

  The heating device 18 includes a coil 22 that is disposed so as to surround the second portion 4 b of the molded body 4. As shown in FIG. 4, the coil 22 is formed of a metal in a tubular shape, and has a space in which a refrigerant can flow. The refrigerant flowing through the coil 22 includes air and other gases, and water and other liquids. The heating device 18 causes a high-frequency eddy current to be generated in the metal film 13 of the molded body 4 by electromagnetic induction by flowing a high-frequency current through the coil 22 via a high-frequency power source (not shown), and the metal film 13 is caused to generate heat. .

  The edge roller 7 is for pulling out the molten glass GM as a plate glass GR having a predetermined width by gripping the width direction end of the molten glass GM falling from the molded body 4. As shown in FIGS. 1 and 2, the edge roller 7 is configured as two left and right roller pairs in a front view so as to grip both ends of the sheet glass GR in the width direction. The edge roller 7 is not limited to the illustrated example, and may be configured as a plurality of stages in the vertical direction. Further, the edge roller 7 may be disposed in the slow cooling furnace 3.

  The slow cooling furnace 3 is disposed below the cooling unit 6. The slow cooling furnace 3 has a plurality of guide rollers 23 arranged at intervals in the vertical direction. The slow cooling furnace 3 gradually cools the glass sheet GR descending through the cooling unit 6 to remove the internal strain. That is, a plurality of heaters 24 are arranged in the vertical direction in the slow cooling furnace 3, and a predetermined temperature gradient is formed in the slow cooling furnace 3 by each heater 24. Thereby, in the slow cooling furnace 3, temperature falls gradually as the plate glass GR falls, and the internal distortion of the plate glass GR is removed.

  Hereinafter, the method to manufacture a glass article using the manufacturing apparatus 1 of the said embodiment is demonstrated. This method demonstrates the case where the plate glass GR is shape | molded as a glass article by the overflow downdraw method.

  Further, in the present method, a case will be described in which a sheet glass GR made of glass having a low forming temperature, a large amount of change in viscosity with respect to a unit temperature change, and a large thermal expansion coefficient is described. Specifically, the case where the plate glass GR comprised with phosphate glass is shape | molded is demonstrated.

As an example of the composition of the phosphate-based glass, in mass%, P ₂ O ₅ : 25% to 60%, Al ₂ O ₃ : _{2 to} 19%, RO (where R is Mg, Ca, Sr and at least one selected from _{Ba): 10~45%, ZnO:} 0~13%, K 2 O: 12~20% ( however, 12%, not including _{20%), Na 2 O:} 0~12% And a composition containing CuO: 0.3 to 20%.

Further, as another example of the composition of the phosphate glass, P ⁵⁺ : 5 to 50%, Al ³⁺ : 2 to 30%, R ′ ⁺ (where R ′ is Li, Na) And at least one selected from K): 10 to 40% and R ²⁺ (where R ²⁺ is at least one selected from Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , and Zn ²⁺ ): 20 A composition containing F ⁻ : 5 to 80% and O ²⁻ : 20 to 95% in terms of ˜50% and anion%, and substantially free of Pb component and As component.

Moreover, as another example of the composition of the phosphate-based glass, P ₂ O ₅ : 5 to 40%, SO ₃ : 1 to 35%, R ′ ₂ O (however, in terms of mol% based on oxide) R ′ is Li, Na or K): 10 to 30%, RO (where R is Mg, Ca, Sr, Ba or Zn): 20 to 50%, and CuO + Fe ₂ O ₃ + CoO + CeO ₂ : 0. The composition containing 001-15% is mentioned.

  This method mainly includes a forming step of forming the plate glass GR by the formed body 4 and a slow cooling step of removing the distortion of the plate glass GR after the forming step.

  In the molding step, the molten glass GM supplied to the molded body 4 in the molding furnace 2 overflows from the overflow groove 8 and flows down along the vertical surface portion 9 and the inclined surface portion 10. In the first space S1, the molten glass GM is heated to a temperature higher than the liquidus temperature by the heating of the heater 14.

  It is desirable that the molten glass GM flowing in the first space S1 is heated to be 50 ° C. or more higher than the liquidus temperature. The liquidus temperature of the molten glass GM in the present embodiment is 800 ° C., and the temperature of the molten glass GM in the first space S1 is 850 ° C. or higher. Moreover, the viscosity of the molten glass GM in the first space S1 is 4.0 Pa · s. In the present specification, “liquid phase temperature” means that a glass powder that passes through a standard sieve 30 mesh (a sieve opening of 500 μm) and remains in 50 mesh (a sieve opening of 300 μm) is placed in a platinum boat, and the temperature gradient The temperature at which crystals are precipitated after being kept in the furnace for 24 hours.

  The molten glass GM flows down the inclined surface portion 10, passes through the opening 20 of the first partition wall 16, and enters the second space S2. The molten glass GM continues to flow down along the inclined surface portion 10 in the second portion 4 b of the molded body 4.

  The second space S2 rapidly cools the molten glass GM flowing down the inclined surface portion 10 corresponding to the second portion 4b to a temperature lower than the liquidus temperature. Specifically, cooling is performed at a cooling rate of −1 to −10 ° C./sec. In this embodiment, the temperature of the surface layer in the cooled molten glass GM is about 500 ° C. or higher and 800 ° C. or lower. However, the interface IF between the molten glass GM and the inclined surface portion 10 of the second portion 4b is heated to a temperature higher than the liquidus temperature.

  As shown in FIG. 4, the molten glass GM that flows along the inclined surface portion 10 flows downward while forming a velocity distribution V. In this case, the flow rate of the molten glass is greatly different between the surface layer side and the interface IF side. That is, the flow rate of the interface IF of the molten glass GM is significantly reduced. For this reason, in order to prevent devitrification of the interface IF of the molten glass GM, the metal film 13 of the molded body 4 is heated by the heating device 18. The heating device 18 causes heat generation due to electromagnetic induction to a part of the metal film 13 (indicated by cross-hatching in FIG. 4) that is located inside the coil 22 by passing a high-frequency current through the coil 22. The metal film 13 in the second portion 4b heats the interface IF of the molten glass GM to a temperature higher than the liquidus temperature by this heat. The interface IF of the molten glass GM in this embodiment is desirably heated to 850 ° C. or higher.

  Further, in the molding process, the coolant flows through the coil 22 in the heating device 18 to cool the coil 22. Since the cooled coil 22 is in the vicinity of the molded body 4, the surface layer of the molten glass GM flowing down the inclined surface portion 10 of the second portion 4b can be cooled. That is, the coil 22 according to the heating device 18 has a function of cooling the surface layer of the molten glass GM in the cooling unit 6 while being a means for heating the metal film 13 of the molded body 4.

  The molten glass GM that flows down the molten glass GM that has flowed down the pair of inclined surface portions 10 is fused and integrated at the lower end portion 11 of the molded body 4. The viscosity of the molten glass GM at the position of the lower end part 11 is adjusted to 300 Pa · s or more by the cooling effect of the cooling part 6. The fused molten glass GM is formed as a plate glass GR. The glass sheet GR is gripped by the edge roller 7 at each end in the width direction, and is drawn downward by the rotation of the edge roller 7.

  Thereafter, the glass sheet GR passes through the opening 21 of the second partition wall 17 and enters the slow cooling furnace 3. In the slow cooling step, the glass sheet GR is gradually cooled according to a predetermined temperature gradient while being guided downward by the guide roller 23. Thereby, the internal distortion of the plate glass GR is removed.

  Thereafter, the glass sheet GR is further cooled by natural cooling (cooling process) and cut into predetermined dimensions (cutting process). Alternatively, the plate glass GR is wound into a roll shape without being cut (winding step).

  According to the glass article manufacturing method and manufacturing apparatus 1 according to the present embodiment described above, the molten glass GM flowing down the molded body 4 is heated to a temperature higher than the liquidus temperature in the first space S1, It flows from the first part 4a to the second part 4b without devitrification. The molten glass GM flowing down the second portion 4b is rapidly cooled to a temperature lower than the liquid phase temperature by the second space S2, so that devitrification does not occur. Furthermore, the interface IF of the molten glass GM flowing down the second portion 4b of the molded body 4 can be heated by heating the metal film 13 of the second portion 4b by the heating device 18. By heating the interface IF of the molten glass GM to be higher than the liquidus temperature, devitrification of the interface IF can be prevented. As described above, the molten glass GM is adjusted to a viscosity suitable for molding in a state where devitrification is prevented.

  FIG. 5 shows a second embodiment of the present invention. In the present embodiment, the outer surface of the molded body 4 is not covered with the metal film 13. A metal body 25 is provided inside the second portion 4 b of the molded body 4. In this embodiment, the inclined surface portion 10 in the second portion 4b of the molded body 4 is heated by induction heating of the metal body 25 located inside the molded body 4 by the heating device 18 (coil 22). Thereby, the molded object 4 can heat interface IF of the molten glass GM which flows down the 2nd part 4b higher than liquid phase temperature.

  FIG. 6 shows a third embodiment of the present invention. In the present embodiment, the heating device 18 is provided inside the molded body 4. That is, the molded body 4 includes a heating element 18 that generates heat by energization inside the second portion 4b. In this embodiment, by heating the inclined surface portion 10 in the second portion 4b by the heating element 18, the interface IF of the molten glass GM flowing down the inclined surface portion 10 can be heated to a temperature higher than the liquidus temperature.

  In addition, this invention is not limited to the structure of the said embodiment, It is not limited to an above-described effect. The present invention can be variously modified without departing from the gist of the present invention.

  In said embodiment, although the example which manufactures plate glass GR by the overflow downdraw method was shown, it is not limited to this. The present invention can also be applied to the case of manufacturing a glass tube by the danna method.

  In said embodiment, although the example which manufactures plate glass GR with phosphate glass was shown, not only this but the manufacturing apparatus 1 can manufacture plate glass GR of various materials. As a material of the plate glass GR to be manufactured, for example, silicate glass and silica glass are used. More specifically, borosilicate glass, soda lime glass, aluminosilicate glass, alkali glass for chemical strengthening, none Examples thereof include alkali glass. The alkali-free glass is a glass that does not substantially contain an alkali component (alkali metal oxide), and specifically, a glass having an alkali component weight ratio of 3000 ppm or less. .

Moreover, this invention can be used also for manufacture of the high refractive index glass suitable for uses, such as organic EL, besides the said glass. Such a high refractive index glass is, for example, in terms of glass composition in terms of mass%, SiO ₂ 0 to 55%, Al ₂ O ₃ 0 to 10%, B ₂ O ₃ 0 to 20%, MgO + CaO + SrO (MgO, CaO, And 0 to 25%, BaO + TiO ₂ + Nb ₂ O ₅ + La ₂ O ₃ + Gd ₂ O ₃ + WO ₃ + Ta ₂ O ₅ + ZrO ₂ (or BaO + TiO ₂ + Nb ₂ O ₅ + La ₂ O ₃ + ZnO + Zr ₂ ) _{~70%, Fe 2 O 3 0~0.1} % ( however, not including 0.1%) is preferably contained.

DESCRIPTION OF SYMBOLS 1 Glass article manufacturing apparatus 4 Molded body 4a First part 4b Second part 13 Metal film (metal)
16 First partition (partition)
GM molten glass GR plate glass (glass article)
S1 1st space S2 2nd space 25 Metal body (metal)

Claims (10)

In a method for producing a glass article comprising a molding step of forming a glass article by causing molten glass to flow down along the surface of the molded body,
The molded body includes an upstream first portion and a downstream second portion,
The first part is arranged in a first space for heating the molten glass flowing down the first part to a temperature higher than a liquidus temperature,
The second part is disposed in a second space that cools the molten glass passing through the first part and flowing down the second part to a temperature lower than a liquidus temperature, A method for producing a glass article. The second part comprises a metal on the surface or inside,
The method for manufacturing a glass article according to claim 1, wherein in the forming step, the metal is heated by electromagnetic induction. The second part has a heating element inside,
The method for manufacturing a glass article according to claim 1, wherein in the forming step, the second portion is heated by the heating element.   4. The glass article according to claim 1, wherein the second portion is provided at a lower portion of the molded body with a length of 10% to 50% with respect to a total height of the molded body. Production method.   The method for producing a glass article according to any one of claims 1 to 4, wherein the first space and the second space are separated by a partition wall.   The said partition is a manufacturing method of the glass article of Claim 5 containing a ceramic.   The said shaping | molding process is a manufacturing method of the glass article as described in any one of Claim 1 to 6 including the process of cooling said 2nd space.   The said shaping | molding process is a manufacturing method of the glass article as described in any one of Claim 1 to 7 which shape | molds plate glass by the overflow downdraw method. The glass article is composed of a phosphate glass containing P ₂ O ₅ 25% or more by mass% as a composition, method for producing a glass article according to any one of claims 1 to 8. An apparatus for producing a glass article comprising a molded body that causes molten glass to flow down along a surface,
The molded body includes an upstream first portion and a downstream second portion,
A high-temperature atmosphere first space in which the first portion upstream of the molded body is disposed, and a low-temperature atmosphere second space in which the second portion downstream of the molded body is disposed. An apparatus for manufacturing glass articles.

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