JP6200304B2 - Continuous superheated steam heat treatment apparatus and method for producing conductive coating film - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a continuous superheated steam heat treatment apparatus and a method for producing a conductive coating film, and in particular, a continuous superheated steam heat treatment apparatus capable of forming a conductive coating film from a copper paste coating film and the production of a conductive coating film. Regarding the method.

  Superheated steam heated further without increasing the saturated steam pressure has a significantly higher radiant heat energy than ordinary heated air at a temperature of 150 ° C. or higher. For this reason, a to-be-processed object can be heated to high temperature easily. Moreover, since it can produce | generate at normal pressure, if a to-be-processed object passes the inside of the processing furnace filled with superheated steam, a continuous heat processing apparatus will be realizable easily. For this reason, a continuous cleaning apparatus using superheated steam and a food heating apparatus have been studied (see, for example, Patent Documents 1 and 2).

  On the other hand, use of superheated steam for heat treatment of a coating film of a conductive paste used in a conductive circuit has been studied (see, for example, Patent Document 3). The conductive paste contains fine metal particles and a binder. By reducing the particle size of the metal particles, the metal particles are fused to each other at a temperature much lower than the melting point of the metal. For this reason, after apply | coating or printing a conductive paste on a board | substrate etc., if it heat-processes, a conductive coating film can be obtained.

  Silver is generally used for the metal particles contained in the conductive paste from the viewpoint of conductivity and stability over time. However, silver is not only expensive, but also has a problem of small amount of resources and ion migration that occurs between circuits under high temperature and high humidity. For this reason, it is expected to use a conductive paste using copper instead of silver. However, copper has a problem that an oxide layer is easily formed, and when heat-treated in air, a conductive coating film having sufficient conductivity cannot be obtained. If the inside of the heat treatment container is replaced with superheated steam, the inside of the heat treatment container can be brought into an oxygen-free state, so that heat treatment can be performed without oxidizing copper. For this reason, it is expected that a conductive coating film having sufficient conductivity can be obtained even in a conductive paste using copper.

JP 2010-1427779 A Japanese Patent Laid-Open No. 2002-199986 International Publication No. 2010/095672 Pamphlet

  However, in order to efficiently obtain a conductive film substrate or the like, continuous processing is desired instead of batch processing. On the other hand, the present inventors have found that a conductive coating film having sufficient conductivity cannot be obtained even if the copper paste coating film is heat-treated by a conventional continuous superheated steam heat treatment apparatus.

  The subject of this application is implement | achieving the continuous superheated steam heat processing apparatus which can perform continuously the heat processing which makes the coating film of copper paste the electroconductive coating film which has sufficient electroconductivity.

  The continuous superheated steam heat treatment apparatus of the present disclosure includes a transport section that transports a film, and a film that is transported by the transport section passes through, and the copper paste coating film that passes along with the film is heat-treated with superheated steam to form a conductive coating film. A heat treatment furnace to be formed, and the heat treatment furnace has a film introduction passage and a discharge passage, and the introduction passage and the discharge passage have a ratio of 3 or more to a depth height.

  In the continuous superheated steam heat treatment apparatus of the present disclosure, each of the introduction passage and the lead-out passage includes a first passage and a second passage that is provided outside the first passage and has a smaller height than the first passage. The second passage may be configured such that the ratio to the depth height is 3 or more.

  In the continuous superheated steam heat treatment apparatus according to the present disclosure, the ratio of the first passage to the depth height may be 3 or more.

  In the continuous superheated steam heat treatment apparatus of the present disclosure, the introduction passage and the lead-out passage may have a configuration in which the height gradually decreases toward the outside.

  In the continuous superheated steam heat treatment apparatus of the present disclosure, the exhaust speed of the exhaust discharged from the introduction passage and the discharge passage may be 4 m / s or more.

  The continuous superheated steam heat treatment apparatus of the present disclosure further includes an exhaust guide attached to at least one of the introduction passage and the lead-out passage, and the exhaust guide has a slit with a bottom face closed and a film passing through the side face. It is good also as a structure which has the exhaust-gas guide main body which has an upper opening.

  In the continuous superheated steam heat treatment apparatus of the present disclosure, the exhaust guide is provided in parallel with each other in the exhaust guide body, and has a plurality of guide plates having slits through which the film passes, and the guide plates are at least above the slits. The portion may be inclined toward the housing.

  The continuous superheated steam heat treatment apparatus of the present disclosure further includes a cooling chamber attached to at least one of the introduction passage and the extraction passage, and the cooling chamber has a slit that is closed at the top and bottom and through which the film passes, You may have the cooling mechanism part which cools the gas in a cooling chamber.

  In the continuous superheated steam heat treatment apparatus of the present disclosure, the transport unit includes a feed unit that feeds out the film and a wind-up unit that winds up the film, and each of the feed unit and the wind-up unit includes a guide roll that guides the transport of the film. And at least one of the guide rolls may have a surface temperature of 80 ° C. or higher and 150 ° C. or lower.

The method for producing a conductive coating film according to the present disclosure includes a step of forming a conductive coating film by passing a film having a copper paste coating film through a heat treatment furnace filled with superheated steam, and the heat treatment furnace Has a film introduction passage and a lead-out passage, and the inside thereof is held at a positive pressure so that superheated steam is discharged from the introduction passage and the lead-out passage. The introduction passage and the lead-out passage have a ratio to the depth height. The amount of exhaust discharged from the introduction passage and the discharge passage is set to 0.45 kg / h · cm ² or more.

  ADVANTAGE OF THE INVENTION According to this invention, the continuous superheated steam heat processing apparatus which can perform continuously the heat processing which makes the coating film of copper paste the electroconductive coating film which has sufficient electroconductivity is realizable.

It is sectional drawing which shows the continuous superheated steam processing apparatus which concerns on one Embodiment. It is a schematic diagram which shows the airflow in a rapid throttle channel. It is sectional drawing which shows an introduction channel. It is sectional drawing which shows the modification of an introduction channel | path. It is sectional drawing which shows the modification of an introduction channel | path. It is sectional drawing which shows an exhaust guide. It is sectional drawing which shows a cooling chamber.

  As shown in FIG. 1, the continuous superheated steam heat treatment apparatus (hereinafter also referred to as a heat treatment apparatus) of the present embodiment includes a conveyance unit 130 for the film 150 and a heat treatment furnace 110 through which the film conveyed by the conveyance unit 130 passes. It has.

  The film conveyance unit 130 includes a film feeding unit 131 and a winding unit 132. The film delivery unit 131 includes a delivery roll 135 and a guide roll 136, and the film winding unit 132 includes a take-up roll 137 and a guide roll 138. A film 150 is stretched between the feed roll 135 and the take-up roll 137, and the film 150 passes through the heat treatment furnace 110 provided between the feed section 131 and the take-up section 132 at a predetermined speed. Moving.

  The heat treatment furnace 110 includes a casing 111 having an introduction passage 115 and a lead-out passage 116 for the film 150, and a superheated steam introduction nozzle 113 provided in the casing 111. The introduction nozzle 113 is connected to a superheated steam generator (not shown). By introducing superheated steam into the housing 111 from the introduction nozzle 113, the interior of the housing 111 can be filled with superheated steam. Excess superheated steam introduced from the introduction nozzle 113 is exhausted from the introduction passage 115, the discharge passage 116, and the exhaust port 117 to the outside of the casing. Thereby, the inside of the housing 111 can be set to a predetermined temperature, and the film 150 passing through the heat treatment furnace 110 can be heat-treated with superheated steam. The exhaust amount discharged from the introduction passage 115 and the discharge passage 116 is determined by the supply amount of superheated steam introduced from the introduction nozzle 113 and the area of the exhaust port 117. For this reason, you may provide a slit etc. in the exhaust port 117 so that exhaust_gas | exhaustion amount can be adjusted. The exhaust port 117 may not be provided depending on the balance between the amount of superheated steam introduced and the exhaust amount.

  In the case of a continuous superheated steam heat treatment apparatus, it is necessary to allow the object to be treated to pass through the heat treatment furnace. For this reason, the heat treatment furnace is not a sealed structure but a structure opened at least in the introduction passage and the outlet passage. For this reason, there is a possibility that outside air may flow in from the introduction passage and the outlet passage. When the outside air containing oxygen flows into the heat treatment furnace, the copper fine powder is oxidized during the heat treatment of the copper paste and does not exhibit conductivity. Further, when air accompanying the film and superheated steam are mixed in the vicinity of the inlet of the introduction passage, the copper fine powder is oxidized and does not exhibit conductivity even when heat-treated in a heat treatment furnace. As a method for preventing the inflow of outside air from the introduction passage and the lead-out passage into the heat treatment furnace, it is conceivable to slightly increase the pressure in the heat treatment furnace. However, even if the inventors of the present application simply generate positive air pressure in the heat treatment furnace and generate an air flow from the introduction passage and the lead-out passage to the outside of the heat treatment furnace, inflow of outside air into the heat treatment furnace or in the vicinity of the introduction passage It has been found that the oxidation of copper fine powder cannot be prevented.

  FIG. 2 schematically shows the airflow in the rapid throttle channel. At the inflection point where the height of the flow path changes, separation of the airflow occurs, but reattachment occurs within a position about three times the height of the flow path. Since the vortex of the separation flow is formed in the flow path, the exhaust resistance is increased, the internal pressure is further increased, and the blowing due to the flow of the outside air can be prevented. In addition, in the flow path where reattachment has occurred, inflow due to the entrainment of outside air hardly occurs, but in the flow path where reattachment does not occur, the outside air is involved and flows into the flow path, so that the introduction passage In the vicinity, there is a region where the air accompanying the film and superheated steam are mixed. For this reason, in order to prevent the inflow of outside air into the heat treatment furnace and not to generate a region where air and water vapor are mixed, a separation vortex is generated in at least a part of the introduction passage and the discharge passage, and It is only necessary to have a streamline distribution in which redeposition has occurred and no inflow due to outside air is involved. Specifically, in the introduction passage and the lead-out passage, the depth L of the passage may be 3 times or more, preferably 4 times or more, more preferably 5 times or more of the height H of the passage.

  FIG. 3 shows the introduction passage 115 in an enlarged manner. The outlet passage 116 has the same configuration as the inlet passage 115. As shown in FIG. 3, the introduction passage 115 has a first passage 121 and a second passage 122 provided outside the first passage 121. The first passage 121 is a slit-shaped opening having a height H1 provided on the side wall of the casing 111 and a depth L1. The second passage 122 is formed by a block-shaped member 118 attached to the outer wall of the casing 111 so as to be aligned with the first passage 121, and is a slit-shaped opening having a height of H2 and a depth of L2. It is. The height H <b> 2 of the second passage 122 is smaller than the height H <b> 1 of the first passage 121. The horizontal width of the slit-shaped opening is a width through which the film 150 can pass.

  In the introduction passage 115, the outer second passage 122 may be used as a rapid throttle flow path, and the first passage 121 may be used as a rapid throttle flow path. In this way, even if a separation vortex caused by the throttle portion of each flow path occurs, the separation vortex adheres in the passage. For this reason, the internal pressure increases due to the increase in exhaust resistance, and the inflow of air from the outside to the second passage 122 and from the second passage 122 to the first passage 121 can be prevented. As a result, the inflow of outside air from the first passage 121 into the heat treatment furnace 110 can be reduced. Specifically, the ratio L1 / H1 of the depth L1 to the height H1 in the first passage 121 may be 3 or more, preferably 4 or more, more preferably 5 or more. Accordingly, the first passage 121 has a streamline distribution in which the separation vortex is reattached, and the inflow of outside air from the first passage 121 into the heat treatment furnace 110 can be prevented. L1 / H1 is preferably as large as possible, but is preferably 20 or less, more preferably 10 or less from the viewpoint of facilitating passage through the film 150. When the height H2 of the second passage 122 satisfies the conditions of L2 / H2> 3 and H2 <H1, a streamline distribution in which separation and reattachment occurs as in the first passage 121 is obtained. Therefore, inflow of outside air into the second passage 122 can be prevented. Moreover, since the flow velocity of superheated steam is increased by using the introduction passage 115 as a rapid constriction flow path, an effect of preventing the inflow of air attached to the film can be obtained. Further, if the lead-out passage 116 has the same configuration as the lead-in passage 115, the inflow of outside air from the lead-out passage 116 into the heat treatment furnace 110 can be prevented.

In order to generate an air flow in the passage, the exhaust amount from the introduction passage 115 and the outlet passage 116 is important. From the viewpoint of preventing the outside air from flowing into the heat treatment furnace 110, it is better that the exhaust amount from the introduction passage 115 and the discharge passage 116 is larger. Specifically, the exhaust amount per unit opening area from the introduction passage 115 and the lead-out passage 116 (hereinafter referred to as a unit flow rate) may be 0.45 kg / h · cm ² or more, and 0.5 kg / h · cm ² or more is preferable, 0.6 kg / h · cm ² or more is more preferable, and 1 kg / h · cm ² or more is particularly preferable. However, from the viewpoint of economy, it is preferable that the unit flow rate of the exhaust gas is 5 kg / h · cm ² or less. Further, the flow rate of the exhaust gas from the introduction passage 115 and the discharge passage 116 is preferably 4 m / s or more, more preferably 5 m / s or more, further preferably 6 m / s or more, and 8 m / s. The above is particularly preferable. The exhaust gas flow rate is preferably 40 m / s or less. The unit flow rate and flow rate of the exhaust can be calculated by the method described in the examples.

  Increasing the thickness of the casing 111 is also preferable from the viewpoint of thermal efficiency because the heat insulation effect is improved. In order to improve the heat insulation of the housing 111, a heat insulating material may be disposed outside the housing 111, or a sandwich panel in which the housing 111 is sandwiched between the heat insulating materials may be formed.

  In addition, although the example in which the introduction passage 115 and the lead-out passage 116 are each configured by two passages having different heights is shown, it may be configured by three or more passages having different heights. In this case, it is only necessary to use a steeply drawn flow path whose height becomes smaller toward the outer passage.

  Furthermore, the height H1 of the first passage 121 and the height H2 of the second passage 122 may be made equal to form one passage. In this case, the combination of the first passage 121 and the second passage 122 becomes a suddenly drawn flow path from the casing 111, resulting in a streamline distribution in which the separation vortex is reattached, and the inflow of air from the outside If it is to prevent. Specifically, (L1 + L2) / H2 may be 3 or more, preferably 4 or more, more preferably 5 or more, and preferably 20 or less, more preferably 10 or less.

  Further, as shown in FIG. 4, when the thickness of the casing 111 is sufficiently thick, the member 118 is not necessarily provided. In this case, the ratio L0 / H0 to the height H0 of the depth L0 of the slit-like passage provided on the side wall of the casing 111 is set to 3 or more, preferably 4 or more, more preferably 5 or more, do it. Even in this case, the value of L0 / H0 is preferably 20 or less, and more preferably 10 or less.

  In addition, although the example where the height of the 1st channel | path 121 and the 2nd channel | path 122 was constant was shown, the height of a channel | path changes as the 1st channel | path 121 and the 2nd channel | path 122 show in FIG. You may do it. When the height of the passage changes, the ratio L / H to the depth height is set to 3 or more, preferably 4 or more, more preferably 5 or more, preferably 20 or less, more preferably 10 based on the largest value. What is necessary is as follows.

  In addition, although the example in which the introduction passage 115 and the outlet passage 116 have the same configuration has been described, if the introduction passage 115 and the outlet passage 116 are both rapid throttle channels, the height and length thereof are different. May be.

  In the heat treatment apparatus of this embodiment, superheated steam is discharged from the introduction passage 115 and the discharge passage 116 of the film 150 to the outside of the apparatus. Since the discharged superheated steam eventually becomes water, if water droplets adhere to the film, the conductivity may be lowered. Therefore, it is preferable to forcibly exhaust the atmosphere in which the heat treatment apparatus is installed in order to prevent water droplets from adhering to the film due to an increase in the atmospheric humidity and to prevent an increase in the atmospheric temperature. When the atmosphere is forcibly exhausted, an air flow is generated around the heat treatment apparatus. In the heat treatment apparatus of the present embodiment, in the introduction passage 115 and the lead-out passage 116 of the film 150, the outermost portion of the passage is used as a rapid drawing passage. For this reason, even if an air current is generated around the apparatus, it is possible to prevent the outside air from entering the housing 111, and there is no problem even if the atmosphere is forcibly exhausted.

  In order to prevent condensation on the film 150, an exhaust guide 160 may be provided outside the introduction passage 115 and the lead-out passage 116 as shown in FIG. The exhaust guide 160 provided on the introduction passage 115 side and the exhaust guide 160 provided on the lead-out passage 116 side have the same configuration. Hereinafter, the exhaust guide 160 provided on the introduction passage 115 side will be described.

  As shown in FIG. 6, the exhaust guide 160 has a slit 165 through which the film 150 passes on the side surface, an exhaust guide body 161 having an upper opening 168 for discharging superheated steam on the upper surface, and an exhaust guide body 161 provided in the exhaust guide body 161. The guide plate 162 is provided. The exhaust guide main body 161 has one of slits 165 connected to the introduction passage 115, and the exhaust discharged from the introduction passage 115 is guided into the exhaust guide main body 161. A guide plate 162 is provided in the exhaust guide body 161. The guide plate 162 is a plate having a slit 166 through which the film 150 passes, and is provided in a direction crossing the film 150. Since the exhaust gas guided into the exhaust guide body 161 is hot, it easily rises along the guide plate 162 and is guided to the upper opening 168. A part of the exhaust gas passes through the slit 166, but a plurality of guide plates 162 are provided in parallel to each other, and most of the superheated steam does not reach the slit 165 on the side opposite to the introduction passage 115 and moves to the upper opening 168 side. Led.

  By connecting the exhaust guide 160 to the introduction passage 115 and the lead-out passage 116, most of the exhaust discharged from the introduction passage 115 and the lead-out passage 116 can be released upward, so that almost no water droplets are present on the surface of the film 150. It will not adhere. The exhaust from the introduction passage 115 and the outlet passage 116 includes superheated steam, saturated steam and super fine water droplets in which the superheated steam is cooled.

It is preferable that the side plate and the guide plate 162 of the exhaust guide main body 161 are inclined toward the housing 111 at least in a portion above the slit 166. Since a rising airflow is generated from the housing, the at least upper part of the side plate of the exhaust guide main body 161 and the guide plate 162 is inclined toward the housing 111 side, so that the discharge of superheated steam or the like is more likely to occur. . If the passage of the film 150 is not hindered, the entire side plate of the exhaust guide body 161 and the guide plate 162 may be inclined toward the housing 111 side. However, the side plate of the exhaust guide body 161 and the guide plate 162 may not be inclined. Further, only one of them may be inclined. FIG. 6 shows an example in which the entire upper surface of the exhaust guide main body 161 is an opening, but the entire upper surface of the exhaust guide main body 161 is not an opening, and a slit-shaped opening or the like is provided. It is good also as composition which has. Further, an opening may be provided on the bottom surface of the exhaust guide body 161.
The size of the exhaust guide 160 may be determined according to the size of the heat treatment furnace 110, the exhaust amount from the introduction passage 115 and the discharge passage 116, and the like. For example, when the unit flow rate of the exhaust gas from the introduction passage 115 and the discharge passage 116 is about 0.45 kg / hr · cm ^{2 to} 5 kg / h · cm ² , the length of the exhaust guide 160 is set to about 30 cm to 1 m. That's fine. In FIG. 6, the example in which the height of the exhaust guide 160 is set higher than that of the casing 111 is shown, but it may be lower than that of the casing 111.

  The number of guide plates 162 may be determined according to the amount of superheated steam discharged from the introduction passage 115 and the discharge passage 116. The effect of suppressing the adhesion of water droplets to the surface of the film 150 is enhanced by providing the guide plate 162, but the guide plate 162 may not be provided. Further, the number of guide plates may be different between the introduction passage 115 side and the lead-out passage 116 side. Furthermore, the exhaust guide 160 may be provided only on one of the introduction passage 115 side and the outlet passage 116 side. In FIG. 6, the exhaust guide 160 is directly connected to the introduction passage 115, but the method of attaching the exhaust guide 160 is not limited, and other members are provided between the exhaust guide 160 and the introduction passage 115. Also good.

  A mechanism for cooling the exhaust gas may be provided outside at least one of the introduction passage 115 and the outlet passage 116. FIG. 7 shows a configuration in which a cooling chamber 171 is connected to the outside of the outlet passage 116. The cooling chamber 171 may be a box shape whose top and bottom are closed, and has an introduction slit 172 and a lead-out slit 173 through which the film 150 passes. Moreover, it has the cooling pipe 174 through which a refrigerant | coolant distribute | circulates as a cooling part which cools the gas in the cooling chamber 171 in the bottom part.

  The exhaust discharged from the outlet passage 116 is introduced into the cooling chamber 171. A part of the exhaust gas introduced into the cooling chamber 171 is cooled by the cooling pipe 174, condenses into water, and is stored at the bottom of the cooling chamber 171. The water stored above a certain level overflows from the discharge port 175 and is discharged. Although the refrigerant | coolant which distribute | circulates the cooling pipe 174 is not specifically limited, Water is preferable.

  By adjusting the number and arrangement of the cooling pipes 174 and the flow rate of the refrigerant, the temperature of the exhaust discharged from the outlet slit 173 can be adjusted. By adjusting the temperature of the exhaust discharged together with the film 150 from the lead-out slit 173, the appearance and electrical characteristics of the conductive film can be further improved.

  The temperature of the exhaust gas discharged from the heat treatment furnace 110 is 300 ° C. or higher, although it depends on the treatment temperature in the heat treatment furnace 110. When the high-temperature exhaust gas is discharged from the heat treatment furnace 110 together with the film 150 and mixed with the outside air, the film is likely to be discolored and the conductivity is lowered due to oxidation by oxygen in the air. By connecting the cooling chamber 171, an intermediate temperature relaxation zone can be provided between the heat treatment furnace 110 and the outside air. Thereby, the discoloration of a film and the electroconductive fall can be suppressed. From the viewpoint of suppressing discoloration of the film and a decrease in conductivity, the temperature of the exhaust from the cooling chamber 171 is preferably 180 ° C. or lower. From the viewpoint of suppressing condensation on the film, the temperature of the exhaust from the cooling chamber 171 is preferably set to 100 ° C. or higher.

  There is no problem even if the cooling pipe 174 is immersed in the water stored in the bottom. The discharge port 175 is not particularly limited, but it is preferable to connect a drain tube and suppress the exhaust discharge and provide an S-shaped trap or the like for water sealing. In FIG. 7, the discharge port 175 is provided on the side surface of the cooling chamber 171, but the discharge port 175 may be provided on the bottom surface of the cooling chamber 171.

  Although the mechanism for cooling the exhaust gas introduced into the cooling chamber 171 by the cooling pipe 174 through which the refrigerant flows is shown in FIG. 7, it may be cooled by other methods. For example, the cooling water may flow into the cooling chamber 171 without using the cooling pipe. In addition, the wall of the cooling chamber 171 can be cooled. From the viewpoint of preventing the condensed water from dripping on the film 150, it is preferable to provide the cooling unit below the film 150.

  The size of the cooling chamber 171 may be appropriately determined according to the size of the heat treatment furnace 110, the amount of exhaust from the outlet passage 116, and the like.

  Although the example in which the cooling chamber 171 is provided on the outlet passage 116 side has been described, the cooling chamber 171 may be provided on the introduction passage 115 side or on both the introduction passage 115 side and the outlet passage 116 side. Also on the introduction passage 115 side, high temperature superheated steam is discharged, which may cause discoloration of the film and decrease in conductivity. By providing the cooling chamber 171 on the introduction passage 115 side, it is possible to suppress discoloration of the film and decrease in conductivity due to oxidation as in the lead-out passage 116 side, and to further improve the appearance and conductivity of the film 150.

  In order to suppress condensation on the film, an exhaust guide 160 may be connected to the outside of the outlet slit 173. Further, the cooling chamber 171 may be connected to one of the introduction passage 115 and the discharge passage 116 and the exhaust guide 160 may be connected to the other.

  When the temperature of the guide roll 136 and the guide roll 138 is low, condensation occurs due to the superheated steam discharged from the introduction passage 115 and the discharge passage 116, and water droplets are likely to adhere to the film. For this reason, the guide roll 136 and the guide roll 138 may be heated. For example, a sheathed heater or the like may be incorporated in the guide roll 136 and the guide roll 138.

  When the guide roll 136 and the guide roll 138 are heated, the surface temperature of the guide roll 136 and the guide roll 138 may be 80 ° C. or higher and 150 ° C. or lower. When water droplets adhere to the film, the film may be dried by blowing dry air or warm air. In particular, it is preferable to completely remove water droplets before winding on the winding roll 137. In the case of blowing warm air, the temperature of the warm air may be 80 ° C. or higher and 150 ° C. or lower.

  The superheated steam introduced from the introduction nozzle 113 can be formed, for example, by heating water to generate saturated steam, and further heating the generated saturated steam. A normal boiler or the like can be used to generate saturated water vapor. For heating the saturated steam, induction heating, high-frequency heating, or the like can be used. Moreover, you may produce | generate superheated steam by carrying out direct induction heating or high frequency heating of water.

  Although FIG. 1 shows an example in which the introduction nozzle 113 is arranged on the top of the casing 111, the introduction nozzle can be arranged at an arbitrary position in the casing 111. For example, you may arrange | position at the lower part of the housing | casing 111. FIG. Moreover, you may arrange | position on both sides on both sides of the film 150.

  Superheated steam may be introduced by mixing with other inert gases. By using the inert gas, the flow rate of the exhaust gas discharged from the introduction passage and the discharge passage can be increased without increasing the amount of water vapor used. Examples of the inert gas include nitrogen, argon, helium and the like, but it is preferable to use nitrogen from an economical viewpoint.

  What is necessary is just to set the temperature inside the housing | casing 111 filled with superheated steam according to the characteristic of the electrically conductive paste to process. In general, in the case of a copper paste using copper, the temperature inside the casing 111 is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, and further preferably 300 ° C. or higher. When the film 150 is a polyimide film, it is preferably 400 ° C. or lower, and more preferably 350 ° C. or lower. The temperature inside the casing 111 can be controlled by the temperature and amount of superheated steam.

  The film 150 may be made of any material as long as it can withstand heat treatment, but a film made of polyimide is preferable. Polyimide is a polymer of a tetracarboxylic dianhydride monomer and a diamine monomer, typified by a polymer of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether. The width, length and thickness of the film 150 can be freely set according to the purpose. For example, in the case of forming a conductive film substrate or the like, a film having a thickness of about 10 μm to about 200 μm can be used.

  The copper paste may be applied or printed on the entire surface of the film 150, or a circuit pattern forming a conductive circuit may be partially applied or printed. Further, the copper paste may be applied or printed only on one surface of the film 150, or may be applied or printed on both surfaces.

  The film 150 is not coated or printed with the copper paste, but the film 150 may be used as another film or substrate with a copper paste coated or printed thereon. In this case, a film or a substrate on which a copper paste is applied or printed may be placed on the film 150 and passed through the heat treatment furnace 110. In this case, the film 150 may be a stainless film or the like.

  The copper paste contains copper fine particles, and any coating material can be used as long as the coating film can be formed by coating or printing on the film and can be made into a conductive coating film by heat treatment. For example, a copper paste containing copper fine particles, an organic binder, and a dispersion medium can be used. In this case, the content of each component is preferably in the range of 5 to 30 parts by mass of the binder and 20 to 400 parts by mass of the dispersion medium with respect to 100 parts by mass of the copper fine particles.

  The copper fine particles may be alloy or composite particles as long as copper is a main component, and the copper content is preferably 80% by mass or more. Examples of metals contained or combined include gold, palladium, silver, nickel, tin and the like. Specifically, copper fine particles formed by a wet reduction method, a gas phase reduction method, an atomization method, or the like can be used. The average particle size of the copper fine particles is preferably 0.01 μm or more and 20 μm or less, and more preferably 0.05 μm or more and 2 μm or less.

  As the binder resin, polyester, polyurethane, polycarbonate, polyether, polyamide, polyamideimide, polyimide, acrylic, or the like can be used. Those having an ester bond, a urethane bond, an amide bond, an ether bond or an imide bond in the resin are preferable because the copper fine particles can be stably dispersed. In addition, when copper fine particles can be stably disperse | distributed, it does not need to contain binder resin.

  When a binder resin that functions to stabilize dispersion is used, the dispersion medium is selected from those that dissolve the resin, and may be an organic compound or water. The dispersion medium has a role of adjusting the viscosity of the dispersion in addition to the role of dispersing the metal fine particles in the dispersion. When an organic solvent is used as the dispersion medium, alcohol, ether, ketone, ester, aromatic hydrocarbon, amide or the like is preferable.

  The copper paste may contain a curing agent, a dispersing agent, a reducing agent, and the like. A reducing agent means what has the capability to reduce | restore metal compounds, such as a metal oxide, a hydroxide, or a salt, to a metal. The reducing agent is preferably one that can be evaporated by superheated steam treatment. Further, when the coating layer of the metal fine particle dispersion is subjected to the superheated steam treatment, it is preferable that the reducing agent remains in the coating layer. Therefore, when the reducing agent is a liquid volatile substance, the boiling point is preferably 150 ° C. or higher. For example, alcohols and polyhydric alcohols can be used.

  A general method can be used for applying or printing the copper paste on the film. For example, a screen printing method, a dip coating method, a spray coating method, a spin coating method, a roll coating method, a die coating method, an ink jet method, a relief printing method, an intaglio printing method, and the like can be used. After coating or printing, a coating film of copper paste can be formed on the surface of the film by evaporating at least a part of the dispersion medium. After forming the coating film made of copper paste, pressure treatment may be performed within a range where the coating film is not destroyed. The coating film of copper paste may be formed on the entire surface of the film depending on the application, or may be a circuit pattern.

  The thickness of the coating film formed from the copper paste may be appropriately selected according to the purpose, but may be about 0.05 μm to 80 μm. The heat treatment time may be appropriately selected depending on the material of the copper paste, the film thickness of the coating film, etc., but can be about 10 seconds to 30 minutes. The heat treatment time may be set according to the length of the heat treatment furnace 110 and the conveyance speed of the conveyance unit 130. Although the conveyance speed of the film 150 can be set freely, it can be set to about 0.2 m / min to 100 m / min.

  The size of the casing 111 can be arbitrarily set according to the required processing capacity. The material of the casing 111 may be any material that can withstand the processing temperature. For example, stainless steel or the like can be used. In FIG. 1, an example in which the film 150 moves in the horizontal direction in the housing 111 is shown, but the film 150 may move in the vertical direction in the housing 111.

  The continuous superheated steam heat treatment apparatus of the present invention uses superheated steam for heat treatment, but additional heating means can be provided for heating the casing 111. Examples of the heating device include a general electric heater and induction heating. By adding these heating means, the start-up time can be shortened and the amount of superheated steam to be used can be reduced.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

-Measurement method-
<Surface resistance>
The surface resistance was measured by a 4-terminal method using a Loresta GP manufactured by Mitsubishi Chemical Analytech.

<Displacement>
The unit flow rate F of the exhaust gas from the introduction passage and the discharge passage was calculated using the following formula 1. The flow velocity v was calculated using the following equation 2. In Formula 1, F is a unit flow rate (kg / h · cm ² ), W is a steam supply amount (kg / h) in terms of mass, and S is a total exhaust area (cm ² ). The total exhaust area is the sum of the opening area of the introduction passage 115, the opening area of the outlet passage 116, and the opening area of the exhaust port 117. In Equation 2, v is the flow velocity (m / s), and V is the total displacement (m ³ / h). V is a value obtained by converting the volume of superheated steam with a density of 0.355 Kg / m ³ into a volume at a temperature of 320 ° C. and 1 atm. V = W (Kg / h) /0.355 (Kg · m ³ ) It is represented by
F = W / S ... Formula 1
v = V / ((S / 10000) / 3600) Formula 2
-Sample-
A polyimide film (manufactured by Kaneka Corporation: Apical 25 NPI) having a width of 257 mm and a thickness of 25 μm was used as the film. The copper paste was adjusted by the following method.

  900 g of copper fine powder (particle diameter 0.3 μm) synthesized by wet reduction method is 250 g of copolymer polyester byron 300 (manufactured by Toyobo Co., Ltd.) (solid content 40 wt%), 350 g of γ-butyrolactone, 500 g of methyl ethyl ketone for 2 hours in a bead mill. The copper paste was prepared by mixing and dispersing. After the viscosity of the obtained paste was appropriately adjusted, a polyimide film was coated on the entire surface by a gravure reverse method to obtain a film in which a copper coating film was formed. The film thickness of the coating applied on the film was 3 μm. The color of the coating film before the heat treatment was purple.

Example 1
The film 150 on which the coating film was formed was heat-treated using the continuous superheated steam heat treatment apparatus shown in FIG. The introduction passage 115 and the discharge passage 116 have a first passage 121 and a second passage 122, respectively.

  The height H1 of the first passage 121 was set to a height that does not hinder the passage of the film, and the ratio L1 / H1 between the depth L1 and the height H1 was 4. The height H2 of the second passage 122 was set such that H1> H2 so as to prevent the passage of the film and to make a throttle channel. The ratio L2 / H2 between the depth L2 and the height H2 was set to 5. In the following description, L2 / H2 is L / H unless otherwise specified. The horizontal width of the first passage 121 and the horizontal width of the second passage 122 were dimensions corresponding to the width of the film.

The film 150 on which the coating film was formed was set on the transport unit 130, transported at a speed of 0.4 m / min, and passed through the heat treatment furnace 110 in 2 minutes 30 seconds. The temperature in the heat treatment furnace 110 was 320 ° C. Superheated steam was supplied from the introduction nozzle 113 to close the exhaust port 117, the unit flow rate of exhaust was 1 kg / h · cm ² , and the flow rate was 8 m / s. The forced exhaust of the atmosphere where the heat treatment apparatus was installed was not performed.

  A purple conductive film was obtained after the heat treatment. Although condensation of water vapor was observed on the surface of the conductive coating film, there was no problem in appearance. The surface resistance of the obtained conductive coating film was 0.093Ω / □.

(Example 2)
The film on which the coating film was formed was heat-treated in the same manner as in Example 1 except that forced evacuation was performed in an atmosphere in which a heat treatment apparatus was installed. A purple conductive film was obtained after the heat treatment. Although condensation of water vapor was observed on the surface of the conductive coating film, there was no problem in appearance. The surface resistance of the obtained conductive coating film was 0.091Ω / □.

(Example 3)
The film on which the coating film was formed was heat-treated in the same manner as in Example 2 except that a heat treatment apparatus in which the exhaust guide 160 was connected to the introduction passage 115 and the discharge passage 116 was used. The exhaust guide 160 has a structure that does not have the guide plate 162. A purple conductive film was obtained after the heat treatment. There was almost no condensation of water vapor on the surface of the conductive coating film, and there was no problem in appearance. However, condensation of water vapor was observed on the upper portion of the exhaust guide 160. The surface resistance of the obtained conductive coating film was 0.082Ω / □.

Example 4
The film on which the coating film was formed was heat-treated in the same manner as in Example 3 except that the exhaust guide 160 having a structure having two guide plates 162 was used. A purple conductive film was obtained after the heat treatment. There was almost no condensation of water vapor on the surface of the conductive coating film, and there was no problem in appearance. No condensation of water vapor was observed at the top of the exhaust guide 160. The surface resistance of the obtained conductive coating film was 0.073Ω / □.

(Example 5)
The film on which the coating film was formed was heat-treated in the same manner as in Example 1 except that a continuous superheated steam heat treatment apparatus with L2 / H2 of 10 was used. The unit flow rate of the exhaust is 2 kg / h · cm ² and the flow rate is 16 m / s. A purple conductive film was obtained after the heat treatment. Although condensation of water vapor was observed on the surface of the conductive coating film, there was no problem in appearance. The surface resistance of the obtained conductive coating film was 0.085Ω / □.

(Example 6)
The film on which the coating film was formed was heat-treated in the same manner as in Example 5 except that the exhaust port 117 was opened. The unit flow rate of exhaust is 0.7 kg / h · cm ² , and the flow rate is 6 m / s. A purple conductive film was obtained after the heat treatment. Although condensation of water vapor was observed on the surface of the conductive coating film, there was no problem in appearance. The surface resistance of the obtained conductive coating film was 0.069Ω / □.

(Example 7)
The film on which the coating film was formed was heat treated in the same manner as in Example 1 except that the exhaust port 117 was opened, the unit flow rate of exhaust was 0.5 kg / h · cm ² , and the flow rate was 4 m / s. It was. A purple conductive film was obtained after the heat treatment. Although condensation of water vapor was observed on the surface of the conductive coating film, there was no problem in appearance. The surface resistance of the obtained conductive coating film was 0.110Ω / □.

(Example 8)
The film on which the coating film was formed was subjected to heat treatment using a heat treatment apparatus having a configuration in which the member 118 was not provided. In this case, the ratio L0 / H0 of the height H0 to the depth L0 of the introduction passage 115 and the lead-out passage is 4, and this value is L / H. The exhaust port 117 was closed. The unit flow rate of exhaust was 0.6 kg / h · cm ² and the flow rate was 5 m / s. Other conditions were the same as in Example 1. A purple conductive film was obtained after the heat treatment. Although condensation of water vapor was observed on the surface of the conductive coating film, there was no problem in appearance. The surface resistance of the obtained conductive coating film was 0.131Ω / □.

Example 9
The film on which the coating film was formed was heat-treated in the same manner as in Example 8 except that forced evacuation was performed in an atmosphere in which a heat treatment apparatus was installed. A purple conductive film was obtained after the heat treatment. Although condensation of water vapor was observed on the surface of the conductive coating film, there was no problem in appearance. The surface resistance of the obtained conductive coating film was 0.194Ω / □.
(Example 10)
The film on which the coating film was formed was heat-treated in the same manner as in Example 5 except that a heat treatment apparatus in which the cooling chamber 171 was connected to the introduction passage 115 and the lead-out passage 116 was used. The unit flow rate of exhaust was 2 kg / h · cm ² and the flow rate was 16 m / s. A purple conductive film was obtained after the heat treatment. Although condensation of water vapor was observed on the surface of the conductive coating film, there was no problem in appearance. The surface resistance of the obtained conductive coating film was 0.065Ω / □.

(Comparative Example 1)
The film on which the coating film was formed was subjected to heat treatment using a heat treatment apparatus having a configuration in which the member 118 was not provided. In this case, the ratio L0 / H0 of the height H0 to the depth L0 of the introduction passage 115 and the discharge passage is 2, and this value is L / H. The exhaust port 117 was closed. The unit flow rate of exhaust was 0.4 kg / h · cm ² and the flow rate was 3 m / s. Other conditions were the same as in Example 1. Even after the heat treatment, the color of the coating film was reddish brown and did not show conductivity. Water vapor condensation was observed on the surface of the coating film after the heat treatment.

(Comparative Example 2)
The film on which the coating film was formed was heat-treated in the same manner as in Comparative Example 1 except that forced evacuation was performed in an atmosphere in which a heat treatment apparatus was installed. Even after the heat treatment, the color of the coating film was reddish brown and did not show conductivity. Water vapor condensation was observed on the surface of the coating film after the heat treatment.

(Comparative Example 3)
The film on which the coating film was formed was heat-treated in the same manner as in Comparative Example 2 except that the unit flow rate of exhaust was 0.5 kg / h · cm ² and the flow rate was 4 m / s. Even after the heat treatment, the color of the coating film was reddish brown and did not show conductivity. Water vapor condensation was observed on the surface of the coating film after the heat treatment.

  The results of each Example and Comparative Example are summarized in Table 1. When L / H was large, the coating film could be a conductive conductive coating film.

  The continuous superheated steam heat treatment apparatus and the method for producing a conductive coating film of the present invention can continuously perform a heat treatment for converting a copper paste coating film into a conductive coating film having sufficient conductivity. The present invention is useful as a heat treatment apparatus for producing a film substrate having a film or the like and a method for producing a film substrate or the like.

110 Heat treatment furnace 111 Housing 113 Introducing nozzle 115 Introducing passage 116 Deriving passage 117 Exhaust port 118 Member 121 First passage 122 Second passage 130 Conveying portion 131 Feeding portion 132 Winding portion 135 Feeding roll 136 Guide roll 137 Winding roll 138 Guide roll 150 Film 160 Exhaust guide 161 Exhaust guide main body 162 Guide plate 165 Slit 166 Slit 168 Upper opening 171 Cooling chamber 172 Introducing slit 173 Deriving slit 174 Cooling pipe 175 Discharge port

Claims (10)

A transport section for transporting the film;
A film transported by the transport unit, and a heat treatment furnace for forming a conductive coating film by heat-treating the copper paste coating film passing through the film with superheated steam;
The heat treatment furnace has an introduction passage and a discharge passage for the film,
The introduction passage and the lead-out passage are continuous superheated steam heat treatment apparatuses in which the ratio to the depth height is 3 or more and 10 or less . Each of the introduction passage and the lead-out passage has a first passage and a second passage provided outside the first passage and having a height smaller than the first passage,
2. The continuous superheated steam heat treatment apparatus according to claim 1, wherein the second passage has a depth ratio of 3 or more and 10 or less . The continuous superheated steam heat treatment apparatus according to claim 2, wherein the first passage has a depth ratio of 3 or more and 10 or less .   The continuous superheated steam heat treatment apparatus according to any one of claims 1 to 3, wherein the introduction passage and the lead-out passage gradually decrease in height toward the outside.   The continuous superheated steam heat treatment apparatus according to any one of claims 1 to 4, wherein a discharge speed of exhaust gas discharged from the introduction passage and the discharge passage is 4 m / s or more. An exhaust guide attached to at least one of the introduction passage and the outlet passage;
6. The exhaust guide according to claim 1, wherein the exhaust guide has an exhaust guide body having a bottom surface closed, a slit through which the film passes on a side surface, and an upper opening on an upper surface. Continuous superheated steam heat treatment equipment. The exhaust guide is provided in parallel to each other in the exhaust guide body, and has a plurality of guide plates having slits through which the film passes,
The continuous superheated steam heat treatment apparatus according to claim 6, wherein at least a portion of the guide plate above the slit is inclined toward the housing side of the heat treatment furnace . A cooling chamber attached to at least one of the introduction passage and the outlet passage;
The said cooling chamber is closed in the upper and lower sides, has a slit through which the said film passes, and has a cooling part which cools the gas in a cooling chamber, The any one of Claims 1-7 Continuous superheated steam heat treatment equipment. The transport unit has a delivery unit for delivering the film and a winding unit for winding the film,
The delivery unit and the winding unit each have a guide roll that guides the conveyance of the film,
The continuous superheated steam heat treatment apparatus according to any one of claims 1 to 8, wherein the surface temperature of at least one of the guide rolls is 80 ° C or higher and 150 ° C or lower. By passing a film having a copper paste coating film through a heat treatment furnace filled with superheated steam, a process for forming a conductive coating film is provided,
The heat treatment furnace has an introduction passage and a discharge passage for the film, and the inside thereof is held at a positive pressure so that the superheated steam is discharged from the introduction passage and the discharge passage.
The introduction passage and the outlet passage have a ratio to the depth height of 3 to 10 ,
A method for producing a conductive coating film, wherein an amount of exhaust discharged from the introduction passage and the discharge passage is 0.45 kg / h · cm ² or more.

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