JP2007017028A - Heat treatment furnace, and method for manufacturing flat display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment furnace capable of preventing warping of a substrate during cooling, and a method for manufacturing a flat display panel using this heat treatment furnace. <P>SOLUTION: The heat treatment furnace 21 is a continuous heat treatment furnace adapted to perform heat treatment of a substrate 31 placed on a setter 32 by passing the substrate with the setter through the inner part. The heat treatment furnace comprises a heating part heating the substrate charged, a cooling part 23 cooling the setter and substrate discharged from the heating part, and a cooling part 24 further cooling the setter and substrate discharged from the cooling part, which are arranged in this order. In the cooling part 23, a cooling means 26 is provided only below a carrying route 25 of the setter and substrate to gradually cool the substrate. In the cooling part (24), cooling means 27 are provided both above and below the carrying route to rapidly cool the substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat treatment furnace for heat-treating the substrate by passing the substrate placed on the setter through the inside of the setter and a method for manufacturing a flat display panel using the heat treatment furnace.

  When manufacturing a plasma display panel (hereinafter also referred to as PDP), a paste is applied on a glass substrate, and the paste is baked to form electrodes, barrier ribs, phosphor layers, and the like. At this time, in order to increase the manufacturing efficiency of the PDP, a continuous firing furnace is used for firing the paste (see, for example, Patent Document 1).

  FIG. 1 is a side view showing a conventional firing furnace. As shown in FIG. 1, the conventional firing furnace 101 has a three-stage configuration, the upper and middle stages are firing zones 2 and 3, respectively, and the lower stage is a discharge zone 104. The firing zones 2 and 3 are provided with heating means (not shown), and the glass substrate 51 is heated while moving the glass substrate 51 from the inlets 2a and 3a toward the outlets 2b and 3b, respectively. A paste or the like formed on the glass substrate 51 is baked. The discharge zone 104 cools the glass substrate 51 while moving the glass substrate 51 from the inlet 104a toward the outlet 104b.

  Further, an elevating part 5 is provided between the outlets 2 b and 3 b of the firing zones 2 and 3 and the inlet 104 a of the discharge zone 104. The elevating unit 5 lowers the glass substrate 51 discharged from the outlet 2 b of the firing zone 2 and the outlet 3 b of the firing zone 3 to the same height as the discharge zone 104 and inserts it into the inlet 104 a of the discharge zone 104.

  A plurality of transport rollers 6 are provided in the firing zones 2 and 3, the discharge zone 104, and the elevating unit 5, respectively. The transport roller 6 extends in a direction perpendicular to the transport direction of the glass substrate 51 (hereinafter referred to as the width direction) and is arranged along the transport direction of the glass substrate 51. And the glass substrate 51 is mounted on the setter 52, and the inside of the baking furnace 101 is conveyed with the setter 52 together. The setter 52 has a thickness of about 1.5 times the thickness of the glass substrate 51, and the size of the setter 52 when viewed from above is slightly larger than that of the glass substrate 51. For example, about 60 setters 52 are provided and are used repeatedly.

  Further, the carry-out zone 104 is composed of seven units 107 arranged in series, and a cooling pipe 108 is disposed above the transport roller 6 in the three preceding units 107. The cooling pipe 108 is cooled by flowing cooling water therein, thereby cooling the glass substrate 51 from above.

  The glass substrate 51 is placed on the setter 52 with an unfired paste (not shown) attached to the upper surface thereof, and the setter 52 is loaded into the firing zone 2 or 3 through the inlet 2a or 3a. Entered. Then, as the transport roller 6 rotates, the heating unit heats the glass substrate 51 while transporting the setter 52 and the glass substrate 51 mounted thereon in the firing zone 2 or 3. Thereby, the paste on the glass substrate 51 is baked. Thereafter, the setter 52 and the glass substrate 51 reach the exit 2b or 3b of the firing zone. At this time, the temperature of the setter 52 and the glass substrate 51 is 350 ° C., for example.

  Thereafter, the setter 52 and the glass substrate 51 are conveyed into the elevating unit 5, and the elevating unit 5 lowers the setter 52 and the glass substrate 51 to the same height as the discharge zone 104, and charges the carry-out zone 104 from the inlet 104 a. Next, the conveyance roller 6 conveys the setter 52 and the glass substrate 51 toward the outlet 104b. At this time, in the three units 107 at the front stage of the discharge zone 104, cooling water having a temperature of, for example, 20 to 30 ° C. flows in the cooling pipe 108, whereby the glass substrate 51 is cooled from the upper side. Is done. Next, the four units 107 at the rear stage of the discharge zone 104 further cool the setter 52 and the glass substrate 51, and then carry out from the outlet 104 b of the discharge zone 104 to the outside of the firing furnace 101. At this time, after the setter 52 is discharged from the outlet 104b, the glass substrate 51 is removed from the setter 52, a new glass substrate 51 before firing is mounted, and again the inlet 2a of the firing zone 2 or the firing zone 3 It is introduced into the firing furnace 101 through the inlet 3a.

JP 2004-293877 A

  However, the conventional techniques described above have the following problems. Recently, in order to improve the productivity of PDP, the tact time has been shortened, and the conveyance speed of the glass substrate 51 in the baking furnace 101 has increased. For this reason, it is necessary to quickly cool the glass substrate 51 that has been fired. As described above, when the setter 52 and the glass substrate 51 placed on the setter 52 move from the elevating unit 5 into the carry-out zone 104, the setter 52 is cooled from above by the cooling pipe 108. At this time, although the upper surface of the glass substrate 51 is rapidly cooled, the setter 52 has a larger heat capacity because its volume is larger than that of the glass substrate 51, and is located behind the glass substrate 51 when viewed from the cooling tube 108, It is hard to be cooled. For this reason, the lower surface of the glass substrate 51, that is, the surface in contact with the setter 52 is less likely to be cooled than the upper surface.

  As a result, in the glass substrate 51, a temperature difference is generated between the upper surface and the lower surface, and both end portions of the glass substrate 51 are warped. If the temperature difference between the upper surface and the lower surface is eliminated, this warpage is also eliminated. However, while the glass substrate 51 is warped, both end portions of the glass substrate 51 are in a floating state in which an air layer is interposed between the glass substrate 51 and the setter 52, and the glass substrate 51 is easily slipped on the setter 52. For this reason, when the setter 52 is being transported by the transport roller 6, the glass substrate 51 may protrude from the setter 52, contact the inner wall of the discharge zone 104, and the glass substrate 51 may be damaged. Moreover, if the amount of protrusion is large, the glass substrate 51 falls from the setter 52. In this case, it is necessary to stop the firing furnace 101 and collect the dropped glass substrate 51, which significantly impedes the productivity of the PDP. Furthermore, when the glass substrate 51 slides on the setter 52, fine scratches are generated on the lower surface of the glass substrate 51, and the quality of the glass substrate 51 is deteriorated.

  Furthermore, if the tact time of the firing furnace is shortened, the amount of heat brought from the firing zone to the discharge zone increases, so that the temperatures of the setter 52 and the glass substrate 51 are unlikely to decrease. As a result, the temperature of the setter 52 and the glass substrate 51 at the outlet 104b of the discharge zone 104 becomes high, for example, 150 ° C. or higher. For this reason, it is necessary to heat-treat the conveyance roller and its peripheral parts arranged on the outlet side of the baking furnace 101, and the equipment cost increases.

  Examples of problems to be solved by the present invention include the above-mentioned problem that the glass substrate is broken, the problem that the productivity of the PDP is lowered, the problem that the quality of the glass substrate is lowered, and the problem that the equipment cost of the baking furnace is increased. As mentioned.

  The heat treatment furnace according to the first aspect of the present invention heats the loaded substrate in a heat treatment furnace that heat-treats the substrate by passing the substrate placed on the setter together with the setter. A heating unit, a first cooling unit that cools the setter and the substrate discharged from the heating unit, and a second cooling unit that further cools the setter and the substrate discharged from the first cooling unit The first cooling unit has a cooling means arranged only below the setter and the substrate transport path.

  A method of manufacturing a flat display panel according to the invention of claim 10 includes a step of depositing a paste on a substrate, a step of firing the paste by placing the substrate on a setter and heating, A first cooling step for cooling the heated setter and the substrate from the lower side, and a second cooling step for further cooling the setter and the substrate cooled from the upper side. And

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 2 is a side view showing the heat treatment furnace according to the present embodiment. As shown in FIG. 2, the heat treatment furnace 21 according to this embodiment performs heat treatment of the substrate 31 by allowing the substrate 31 placed on the setter 32 to pass through the interior of the setter 32. In the heat treatment furnace 21, a heating unit 22 that heats the loaded substrate 31, a setter 32 that is discharged from the heating unit 22, a cooling unit 23 that cools the substrate 31, and a setter that is discharged from the cooling unit 23. 32 and a cooling unit 24 for further cooling the substrate 31 are provided in this order. The insides of the heating unit 22 and the cooling units 23 and 24 are in communication with each other. In the cooling unit 23, a cooling unit 26 is provided only below the setter 32 and the transport path 25 for the substrate 31. In the cooling unit 24, cooling means 27 are provided both above and below the transport path 25.

  The heat treatment furnace 21 is, for example, a flat panel display manufacturing apparatus, for example, a plasma display panel (PDP) firing furnace. For example, the substrate 31 is a glass substrate that constitutes the back substrate of the PDP, and a paste that is a raw material for electrodes, partition walls, or phosphor layers is deposited on the substrate 31. And the heat processing furnace 21 forms an electrode, a partition, or a fluorescent substance layer by baking this paste.

  Next, the operation of the heat treatment furnace according to the present embodiment, that is, the method for manufacturing the flat display panel according to the present embodiment will be described. First, a paste (not shown) is deposited on the substrate 31. Next, the substrate 31 is placed on the setter 32 and the setter 32 is loaded into the heating unit 22 of the heat treatment furnace 1. Then, the heating unit 22 heats the setter 32 and the substrate 31 while heating, thereby baking the paste. Next, the setter 32 and the board | substrate 31 are conveyed in the cooling part 23, and the heated setter 32 and the board | substrate 31 are cooled from the downward side. Next, the setter 32 and the board | substrate 31 are conveyed in the cooling part 24, and the setter 32 and the board | substrate 31 are cooled from both the upper side and the lower side. In this way, the constituent elements are formed on the substrate of the flat display panel. This component is, for example, a PDP electrode, a partition wall, or a phosphor layer.

  Next, the effect of this embodiment will be described. According to this embodiment, in the cooling unit 23, the cooling means 26 is provided only below the transport path 25, and the setter 32 and the substrate 31 are cooled from the lower side, that is, the setter 32 side. Yes. Thereby, since the board | substrate 31 is cooled via the setter 32, the board | substrate 31 can be cooled slowly. As a result, a large temperature difference does not occur between the lower surface and the upper surface of the substrate 31, and the substrate 31 does not warp. For this reason, problems such as collision of the substrate 31 with the inner wall of the heat treatment furnace, dropping from the setter 32, and generation of scratches on the substrate 31 due to warpage of the substrate 31 do not occur.

  In the present embodiment, the cooling unit 24 is provided with cooling means 27 both below and above the transport path 25 so as to cool the setter 32 and the substrate 31 from both below and above. It has become. Thereby, the setter 32 and the board | substrate 31 can fully be cooled. As a result, it is not necessary to heat-resistant parts such as the transport roller and its peripheral parts disposed on the outlet side of the firing furnace, and the equipment cost can be reduced.

  Next, examples of the present invention will be described. FIG. 3 is a side view showing a firing furnace according to an embodiment of the present invention, FIG. 4 (a) is a side view showing a unit constituting the quenching zone of the firing furnace shown in FIG. 3, and FIG. FIG. The firing furnace according to the present embodiment is a firing furnace for firing the paste deposited on the back substrate of the plasma display panel to form electrodes, barrier ribs, or phosphor layers, and the substrate is continuously formed therein. It is a continuous firing furnace that is passed through and fired.

  As shown in FIG. 3, the firing furnace 1 according to the present embodiment has a three-stage configuration, the upper stage and the middle stage are firing zones 2 and 3, respectively, and the lower stage is a discharge zone 4. The firing zones 2 and 3 are portions for heating the glass substrate 51 and firing a paste or the like formed on the glass substrate 51. Moreover, the discharge zone 4 is a part which cools the glass substrate 51 after baking. Further, an elevating part 5 is provided between the firing zones 2 and 3 and the discharge zone 4. The elevating unit 5 lowers the glass substrate 51 discharged from the firing zone 2 and the firing zone 3 to the same height as the discharge zone 4 and inserts it into the discharge zone 4.

  A plurality of conveying rollers 6 are provided in the firing zones 2 and 3, the discharge zone 4, and the elevating unit 5, respectively. The transport roller 6 has a rotation axis extending in a direction (width direction) orthogonal to the transport direction of the glass substrate 51, and is arranged along the transport direction of the glass substrate 51. The glass substrate 51 is mounted on a setter 52, and the setter 52 is transported through the firing furnace 1 by the transport roller 6. That is, the conveyance path of the glass substrate 51 and the setter 52 is on the conveyance roller 6. The setter 52 has a thickness of about 1.5 times the thickness of the glass substrate 51, and the size when viewed from above is slightly larger than the glass substrate 51. For example, about 60 setters 52 are provided and are used repeatedly.

  The firing zones 2 and 3 are provided with heating means (not shown). The firing zone 2 is composed of seven units 2c arranged in series and communicated with each other. While moving the glass substrate 51 together with the setter 52 from the entrance 2a to the exit 2b of the firing zone 2, the glass substrate 51 and the setter 52 are heated, and the paste formed on the glass substrate 51 is baked. Similarly, the firing zone 3 is composed of seven units 3c arranged in series and communicated with each other. While moving the glass substrate 51 together with the setter 52 from the inlet 3a to the outlet 3b of the firing zone 3, The glass substrate 51 and the setter 52 are heated, and the paste formed on the glass substrate 51 is baked. The firing zones 2 and 3 heat the setter 52 and the glass substrate 51 to, for example, 300 to 400 ° C., for example, 350. The firing zones 2 and 3 can perform the firing process in parallel, and the outlets 2b and 3b are connected to the elevating unit 5, respectively.

  Further, the carry-out zone 4 is composed of, for example, seven units arranged in series and communicated with each other. For example, the four units 7a in the front stage constitute the slow cooling zone 11, and, for example, three units in the rear stage. 7 b constitutes the quenching zone 12. The slow cooling zone 11 moves the setter 52 and the glass substrate 51 of a relatively high temperature, for example, about 350 ° C. carried out from the elevating unit 5 in the conveyance direction by rotating the conveyance roller 6, for example, to about 200 ° C. This is the part to be cooled. The quenching zone 12 moves the setter 52 and the glass substrate 51, which are carried out from the slow cooling zone 11, at a relatively low temperature, for example, about 200 ° C., by rotating the carrying roller 6 in the carrying direction, for example to 100 ° C. or less. This is the part to be cooled. The units 7a and 7b can be attached to and detached from the firing furnace 1 independently of each other. Thereby, the number of units constituting the slow cooling zone 11 and the rapid cooling zone 12 can be changed.

  In each unit 7 a constituting the slow cooling zone 11, four cooling means 9 are provided below the transport path of the setter 52 and the glass substrate 51, that is, below the transport roller 6. And the glass substrate 51 is cooled from the lower side, ie, the setter 52 side. On the other hand, in each unit 7b constituting the quenching zone 12, four cooling means 9 are provided below and above the transport path of the setter 52 and the glass substrate 51, that is, below and above the transport roller 6, respectively. Thereby, the setter 52 and the glass substrate 51 are cooled from both the lower side and the upper side.

  As shown in FIGS. 4A and 4B, each cooling means 9 is composed of a plurality of fins 10 and one cooling pipe 8 that passes through the fins 10 and reciprocates in the width direction three times. The cooling pipe 8 is configured such that cooling water flows through the cooling pipe 8. The surfaces of the fins 10 are parallel to the transport direction and the vertical direction, and the fins 10 are arranged in the width direction. The distance between the cooling means 9 and the conveyance path can be adjusted. For example, the cooling means 9 is arranged at a position as close as possible to the conveyance path. In addition, in FIG.4 (b), illustration of the glass substrate 51 is abbreviate | omitted for convenience.

  Next, the operation of the firing furnace according to the present embodiment configured as described above will be described. The operation of the firing furnace according to the present embodiment is a part of the method for manufacturing the PDP according to the present embodiment. First, a method for manufacturing a PDP according to the present embodiment will be described. An electrode forming paste (not shown) is applied to the entire surface of the glass substrate 51, and the paste is dried and patterned into a predetermined shape. Then, the glass substrate 51 is placed in the firing furnace 1 shown in FIG. 3, and the paste is fired by heating to form a plurality of data electrodes parallel to each other. The firing method at this time will be described later. Next, a white dielectric layer is formed so as to cover the data electrode. Next, a partition wall forming paste is applied in a matrix or stripe form on this white dielectric layer and dried, and then the glass substrate 51 is placed in the firing furnace 1 and the paste is baked to form the partition walls. Form. Next, a phosphor layer forming paste is applied to the inside of the partition walls and dried, and then the glass substrate 51 is put into the firing furnace 1 and the paste is baked to form the phosphor layer. Thereby, a back substrate is produced.

  On the other hand, a plurality of scanning electrodes and a common electrode are alternately and parallelly formed on a transparent substrate such as a glass substrate. Next, a transparent dielectric layer is formed so as to cover the scan electrode and the common electrode. Next, a protective film made of, for example, MgO is formed on the transparent dielectric layer. Thereby, a front substrate is produced. Then, the front substrate and the rear substrate manufactured as described above are overlapped. At this time, the direction in which the scanning electrode and the common electrode on the front substrate extend and the direction in which the data electrode on the rear substrate extends are orthogonal to each other. Next, after sealing both substrates and exhausting the inside of the cell, a discharge gas is sealed in the cell. Thereby, PDP can be manufactured.

  Next, a paste baking method in each step of forming the data electrodes, the barrier ribs, and the phosphor layer on the back substrate will be described in detail. FIG. 5 is a graph showing the temperature profile of the firing treatment in this example, with time on the horizontal axis and temperature on the vertical axis. As shown in FIG. 3, first, the glass substrate 51 is placed on the setter 52 with an unfired paste (not shown) attached to the upper surface thereof. Then, the setter 52 is charged into the firing zone 2 or 3 through the inlet 2a or 3a. Next, by rotating the transport roller 6, the heating unit heats the setter 52 and the glass substrate 51 while transporting the setter 52 and the glass substrate 51 mounted thereon in the firing zone 2 or 3 in the transport direction.

  At this time, among the seven units constituting the firing zone, for example, the previous three units function as a temperature raising zone, and the temperature of the setter 52 and the glass substrate 51 is raised to, for example, 350 ° C. as shown in FIG. To do. The four units at the rear stage function as a keep zone, and keep the temperatures of the setter 52 and the glass substrate 51 at a keep temperature, for example, 350 ° C. Thereby, the paste deposited on the glass substrate 51 is fired, and the setter 52 and the glass substrate 51 reach the exit 2b or 3b of the firing zone. At this time, the temperature of the setter 52 and the glass substrate 51 is 350 ° C., for example.

  Then, the setter 52 and the glass substrate 51 are conveyed into the elevating unit 5, lowered to the same height as the discharge zone 4 by the elevating unit 5, and carried into the slow cooling zone 11 of the carry-out zone 4. Thereafter, by rotating the transport roller 6, the setter 52 and the glass substrate 51 are sequentially passed through the four units 7a and the three units 7b toward the outlet 4b of the discharge zone 4.

  At this time, in the slow cooling zone 11, cooling water having a temperature of, for example, 20 to 30 ° C. is circulated in the cooling pipe 8 of the cooling means 9 provided below the conveyance path. Thereby, the cooling pipe 8 is cooled, and then the fin 10 is cooled. As a result, the setter 52 and the glass substrate 51 are cooled from the lower side. The setter 52 and the glass substrate 51 are first cooled on the lower surface of the setter 52 and then cooled to the upper surface of the setter 52, and the glass substrate 51 is cooled accordingly. At this time, since the glass substrate 51 is cooled via the setter 52 having a larger heat capacity than the glass substrate 51, the glass substrate 51 is cooled at a cooling rate lower than that of the related art. Thereby, the setter 52 and the glass substrate 51 are cooled to 200 ° C., for example.

  Next, the setter 52 and the glass substrate 51 are conveyed to the quenching zone 12. In the rapid cooling zone 12, the setter 52 and the glass substrate 51 are cooled from both the lower side and the upper side by the cooling means 9 provided below and above the conveyance path. Thereby, the setter 52 and the glass substrate 51 are rapidly cooled, and the temperature becomes, for example, 100 ° C. or less.

  Thereafter, the setter 52 and the glass substrate 51 are carried out of the firing furnace 1 from the outlet 4 b of the discharge zone 4. Thereby, the baking process of the paste is completed. Note that after the setter 52 is discharged from the outlet 4b, the glass substrate 51 is removed from the setter 52, and a new unfired glass substrate 51 is mounted. Again, the entrance 2a of the firing zone 2 or the entrance of the firing zone 3 It is put into the firing furnace 1 through 3a.

  Next, the effect of the present embodiment will be described. According to the present embodiment, in the slow cooling zone 11, the cooling means 9 is provided only below the transport path of the setter 52 and the glass substrate 51, and the setter 52 and the glass substrate 51 are cooled from the lower side. It has become. Thereby, the glass substrate 51 is cooled via the setter 52 having a larger heat capacity than the glass substrate 51. As a result, a large temperature difference does not occur between the setter 52 and the glass substrate 51, and the glass substrate 51 is not rapidly cooled. Therefore, a large temperature difference does not occur between the lower surface and the upper surface of the glass substrate 51, and the glass substrate 51 does not warp. As a result, the glass substrate 51 does not slide on the setter 52, protrudes from the setter 52, collides with the inner wall of the firing furnace, or falls from the setter 52. Further, the lower surface of the glass substrate 51 is not damaged by sliding.

  Generally, when cooling a glass substrate, it is very important to cool slowly. For example, when producing plate glass, the glass is melted at a high temperature and formed into a plate shape, and then cooled to room temperature. At this time, if it cools rapidly, distortion will arise in glass and it will cause a crack. In order to avoid this, when the glass is cooled, the glass is gradually cooled with a certain temperature curve. At this time, the annealing point and the strain point are important. The annealing point is a temperature at which glass distortion is not eliminated below that temperature, and the strain point is the temperature at which glass distortion does not occur below that temperature. That is, the temperature range from the strain point to the annealing point is a temperature range in which distortion occurs in the glass but is not eliminated. The strain point is about 500 ° C. for plate glass (soda lime glass), about 570 ° C. for high melting point / low shrinkage glass (eg PD200), and the annealing point is about 30 to 100 ° C. higher than the strain point. ing. When cooling the glass, it is possible to substantially prevent the occurrence of distortion by gradually cooling the temperature range from the annealing point to the strain point. Further, even in a glass having strain, the strain can be removed by reheating to a temperature equal to or higher than the annealing point and then cooling.

  In this embodiment, when the glass substrate is carried into the carry-out zone, the temperature of the glass substrate is 300 to 400 ° C., for example, 350 ° C. Therefore, the cooling in the discharge zone is performed in the temperature range below the strain point described above. It becomes cooling. For this reason, even if the glass substrate is rapidly cooled, no distortion remains in the glass substrate. However, as described above, when the glass substrate is rapidly cooled from the upper surface side, the heat capacity of the setter is larger than the heat capacity of the glass substrate, so the setter cannot keep up with the temperature change of the glass substrate, and there is a large temperature difference with the glass substrate. appear. As a result, a large temperature difference is generated between the upper surface and the lower surface of the glass substrate, and the glass substrate is warped. Thereby, the glass substrate becomes slippery on the setter, and various problems occur as described above. On the other hand, in the present embodiment, by cooling the glass substrate from the setter side, the glass substrate can be gradually cooled while maintaining the temperatures of the setter and the glass substrate substantially equal to each other. The temperature difference between the two can be suppressed and the occurrence of warpage can be prevented.

  In the present embodiment, in the quenching zone 12, cooling means 9 are provided both below and above the conveyance path so that the setter 52 and the glass substrate 51 are cooled from both below and above. It has become. Thereby, the setter 52 and the glass substrate 51 can be rapidly cooled, and the setter 52 and the glass substrate 51 can be sufficiently cooled. As a result, for example, the temperature of the setter 52 and the glass substrate 51 can be set to 100 ° C. or less at the outlet of the firing furnace 1. As a result, it is not necessary to heat-resistant parts such as the transport roller and its peripheral parts disposed on the outlet side of the firing furnace, and the equipment cost can be reduced. In the rapid cooling zone 12, since the setter 52 and the glass substrate 51 are rapidly cooled, there is a temperature difference between them, but since the temperature of both is 200 ° C. or less, the glass substrate 51 does not warp. .

  Furthermore, in this embodiment, the unit 7a constituting the slow cooling zone 11 and the unit 7b constituting the quenching zone 12 can be attached to and detached from the firing furnace 1 independently of each other. Can be adjusted. Thereby, the length of the slow cooling zone 11 and the rapid cooling zone 12 can be adjusted, and even when the cooling capacity per unit is constant, the temperature profile in the cooling process can be arbitrarily adjusted.

  Furthermore, in the present embodiment, the distance between the transport path of the setter 52 and the glass substrate 51 and the cooling means 9 can be adjusted. Thereby, the temperature profile in a cooling process can be adjusted arbitrarily.

  In the present embodiment, an example is shown in which water is circulated through the cooling pipe. However, the present invention is not limited to this, and a cooling medium other than water, such as air, may be circulated.

  Further, the keep temperature in the firing zones 2 and 3 depends on the characteristics of the material used and the manufacturing process. However, in this embodiment, even if the keep temperature is equal to or higher than the strain point, the glass substrate 51 is cooled via the setter 52 in the slow cooling zone 11, so the cooling rate is reduced, and the glass substrate No distortion occurs in 51.

  According to the present embodiment, in the slow cooling zone, the cooling means is provided only below the conveyance path, and the setter and the glass substrate are cooled from the lower side thereof, so that the glass substrate passes through the setter. And cooled. For this reason, a glass substrate can be gradually cooled, without producing a big temperature difference between a setter and a glass substrate. As a result, the temperature difference between the lower surface and the upper surface of the glass substrate can be suppressed, and the glass substrate does not warp.

It is a side view which shows the conventional baking furnace. It is a side view which shows the heat processing furnace which concerns on embodiment of this invention. It is a side view which shows the baking furnace which concerns on the Example of this invention. (A) is a side view which shows each unit which comprises the discharge zone of the baking furnace shown in FIG. 3, (b) is the top view. It is a graph which shows the temperature profile of the baking process in a present Example by taking time on a horizontal axis and taking temperature on a vertical axis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Firing furnace 2, 3; Firing zone 4; Discharge zone 5; Elevating part 6; Conveying roller 7a, 7b; Unit 8; Cooling pipe 9; Cooling means 10; Furnace 22; Heating unit 23, 24; Cooling unit 25; Transfer path 26, 27; Cooling means 31; Substrate 32; Setter 51; Glass substrate 52; Setter

Claims (12)

In a heat treatment furnace for heat-treating the substrate by passing the substrate placed on a setter together with the setter, a heating unit for heating the loaded substrate, and the setter discharged from the heating unit And a first cooling unit that cools the substrate, and a second cooling unit that further cools the setter and the substrate discharged from the first cooling unit, wherein the first cooling unit includes: A heat treatment furnace having cooling means disposed only below the setter and the substrate transfer path. 2. The heat treatment furnace according to claim 1, wherein the second cooling section includes other cooling means disposed both above and below the transfer path. The heat treatment furnace according to claim 1 or 2, wherein each of the first and second cooling sections is configured by connecting a plurality of units in series with each other. The heat treatment furnace according to claim 3, wherein each of the units is detachable. The heat treatment furnace according to any one of claims 1 to 4, wherein a distance between the cooling means and the transfer path is adjustable. The heat treatment furnace according to any one of claims 1 to 5, wherein the cooling means includes a cooling pipe through which a cooling medium flows. The heat treatment furnace according to claim 6, wherein the cooling medium is water. The heat treatment furnace according to claim 6, wherein the cooling medium is air. A firing furnace for a plasma display panel, in which a paste as a raw material for electrodes, barrier ribs or phosphor layers is deposited on the substrate, and the paste is fired to form the electrodes, barrier ribs or phosphor layers. The heat treatment furnace according to claim 1, wherein the heat treatment furnace is provided. A step of depositing a paste on a substrate; a step of firing the paste by placing and heating the substrate on a setter; and a first cooling the heated setter and the substrate from below. And a second cooling step of further cooling the setter and the substrate cooled from the upper side, and a method of manufacturing a flat display panel. 11. The method for manufacturing a flat display panel according to claim 10, wherein, in the second cooling step, the setter and the substrate are cooled from both the upper side and the lower side thereof. The method for manufacturing a flat display panel according to claim 10 or 11, wherein the flat display panel is a plasma display panel, and the paste is used as a raw material for electrodes, barrier ribs or phosphor layers.

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