JP2018013321A - Dry method and drying furnace for roughened aluminum foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a treatment time, regarding a drying furnace used for dryness of a roughened aluminum foil using in an aluminum electrolytic capacitor.SOLUTION: A dry furnace comprises: a pretreatment mechanism having a structure configured to cause a far-infrared heater to heat and evaporate washing water adhering to an aluminum foil surface, and discharge to the outside steam generated by heating; and a body mechanism configured to heat an aluminum foil with an air heating system. The dry furnace is configured to dry an erosion part where after the surface of the aluminum foil is dried by the pretreatment mechanism, the aluminum foil is roughened by the body mechanism, to prevent temperature reduction of the aluminum foil due to evaporation heat of washing water, thereby shortening a drying time of the aluminum foil.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method and a drying furnace for drying cleaning water attached to an aluminum foil that is used for manufacturing an aluminum electrolytic capacitor or the like and subjected to a surface roughening treatment and then washed with water.

  In the conventional drying device, after washing the electrolytic solution adhering to the roughened aluminum foil, the aluminum foil is transferred to the drying device, and the aluminum foil is heated by an electric furnace, gas furnace, hot air furnace, etc. The cleaning water adhering to the surface of the aluminum foil and the cleaning water remaining in the erosion part of the surface of the aluminum foil generated by the roughening treatment are both dried (see, for example, the following patent document). In this specification, the method of raising the temperature of the aluminum foil and drying it is called an air heating method in this specification.

There is no description in the prior art documents that far infrared rays are used for drying the roughened aluminum foil.

Japanese Patent Laid-Open No. 10-223491

  However, the aluminum foil after washing is in a state where water adheres so as to cover the entire surface. In the conventional air heating method using a drying furnace, the temperature of the aluminum foil decreases due to the heat of evaporation of water adhering to the surface of the aluminum foil, so it took a long time for the aluminum foil to reach the temperature required for drying. .

  In addition, since the evaporated water stays in the furnace, the furnace is contaminated by moisture during long-term operation of the furnace.

  In the production of an aluminum electrolytic capacitor or the like, the drying method according to the present invention uses cleaning water adhered to the surface of the aluminum foil by far infrared rays in order to dry the cleaning water adhered to the surface of the aluminum foil that has been subjected to the roughening treatment. A first step of directly heating and evaporating the cleaning water; and a second step of drying the cleaning water remaining in the eroded portion of the aluminum foil subjected to the roughening treatment by an air heating method following the first step. A method for drying an aluminum foil having

  Moreover, the drying furnace which concerns on this invention is a drying furnace used in said 1st process, and has a far-infrared heater. This far-infrared heater generates radiation with a wavelength in the vicinity of 3 μm, which is the maximum absorption wavelength of water, so that the cleaning water adhering to the surface of the aluminum foil can be directly heated rather than heat conduction from the aluminum foil. to enable.

  Preferably, the drying furnace according to the present invention has a structure for discharging water vapor generated by directly heating the cleaning water to the outside of the furnace.

  According to the present invention, a relatively large amount of cleaning water present on the surface of the aluminum foil in the first step is directly evaporated and removed by evaporation, and then the aluminum foil is transferred to the second step. The eroded portion of the aluminum foil is dried by increasing the temperature of the aluminum foil itself. Therefore, the required temperature can be obtained without lowering the temperature of the aluminum foil due to the evaporation heat of the cleaning water present on the surface in the second step, and the drying process time can be shortened.

Explanatory drawing (top view) of the drying furnace for aluminum electrolytic capacitor chemical conversion treatment. Explanatory drawing of a drying furnace for chemical conversion treatment of aluminum electrolytic capacitors (side sectional view) Explanatory drawing of an aluminum foil erosion part.

  Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the function of the present invention is realized by connecting a pre-processing mechanism (the first step) having a far-infrared heater immediately before the drying furnace by the air heating method (the second step). To do.

  1 to 3, reference numeral 1 denotes an aluminum foil, which is rolled in a roll shape with an aluminum purity of 99.99%, a width of 500 mm, and a thickness of 0.2 mm, and has a surface roughened.

  The aluminum foil 1 subjected to the roughening treatment is subjected to a positive oxide film treatment to form an insulating thin film on the aluminum foil 1. FIG. 3 is an explanatory view of an aluminum foil erosion portion schematically showing a cross section of the aluminum foil 1 after such treatment, and many fine erosion portions 8 are formed on the surface of the aluminum foil 1.

  In FIG. 1 and FIG. 2, the aluminum foil 1 unwound from the roll is cleaned of the surface of the surface and the erosion unit 8 by the cleaning water 6.

  The aluminum foil 1 from which the oxidization coating solution adhering to the cleaning water 6 has been removed is transferred to the pretreatment mechanism 4, and the cleaning water adhering to the surface of the aluminum foil 1 is heated and dried by the far infrared heater 5. The radiation wavelength of the far-infrared heater 5 to be used is desirably around 3 μm, which is the maximum absorption wavelength of the cleaning water 6.

Here, the grounds will be described. In the paper by Ikuo Watanabe and Ken Shimizu, “Use of electromagnetic waves in the food industry (1)” (Chemical Technology Journal, MOL, pp120-128, February 1988), the infrared absorption wavelength dependence of water is described. Yes. This describes the change in the absorption wavelength due to the change in the thickness of the water layer with respect to the absorption wavelength of water. According to this, the absorptance is high at ± 0.2 μm centered on a wavelength of 3 μm, and the temperature corresponding to this is the “Vienna displacement side” (a law in which the wavelength of the peak of radiation from a black body is inversely proportional to the temperature. ) From λm = (3 ± 0.2) μm = 2.896 / (T ± 273), T = 632 ° C. ≦ T ≦ 761 ° C. is obtained.
Therefore, the temperature of the heating element to be used is preferably within this temperature range or in the vicinity thereof, and further, since the heat generation temperature of the far-infrared heater and the power consumption are proportional, the power consumption is reduced. It is desirable to set the heating temperature of the heater.

  In this embodiment, a far-infrared heater manufactured by Asahi Denshi Seisakusho Co., Ltd .: a quartz tube (rated 127 V / 1.2 kW) is used with a total of three, one upper part and two lower parts in a direction perpendicular to the feeding direction of the aluminum foil 1. The infrared heater surface temperature was set to 630 ° C. The internal temperature of the pretreatment mechanism 4 is 300 ° C., and the surface temperature of the aluminum foil 1 is 400 ° C.

  According to such a configuration, the cleaning water adhering to the surface of the aluminum foil 1 is directly heated to evaporate and dry, so that the pretreatment mechanism 4 does not need to maintain its internal temperature at a high temperature. Accordingly, it is possible to provide the water vapor outlet 7 that would otherwise cause a decrease in internal temperature.

  In this embodiment, the discharge port 7 is formed on the upper surface of the pretreatment mechanism 4 and has a slit shape having a length of 500 mm and a width of 20 mm in a direction perpendicular to the feeding direction of the aluminum foil 1. Thereby, water vapor generated when the cleaning water adhering to the surface of the aluminum foil 1 is heated is effectively discharged from the discharge port 7.

  After the surface of the aluminum foil 1 is dried, the aluminum foil 1 is transferred to the main body mechanism 2 to dry the erosion part 8 generated by the roughening treatment.

  The main body mechanism 2 uses the sheathed heater 3 to heat the aluminum foil 1 by an air heating method so that the internal temperature of the main body mechanism 2 is 570 ° C., and evaporates the cleaning liquid remaining in the eroded portion 8 of the aluminum foil 1 to dry it. To do. Tomioka Sangyo Co., Ltd.'s sheathed heater: Incoloy 800 (rated 127V / 750W) is used for heating inside the main body mechanism 2, and a total of 18 pieces, 9 in the vertical direction and perpendicular to the feed direction of the aluminum foil 1, are provided. used. The temperature of the sheathed heater was set to 800 ° C.

  In this embodiment, the cleaning water adhering to the surface of the aluminum foil 1 is dried in advance by the pretreatment mechanism 4. Therefore, when the aluminum foil 1 is heated by the main body mechanism 2, there is no temperature drop due to evaporation heat when the cleaning water adhering to the surface of the aluminum foil 1 evaporates as in the conventional example. Therefore, it is possible to easily maintain the required temperature, and the drying time of the aluminum foil 1 can be shortened.

  In the drying furnace of the present embodiment, the transfer speed of the conventional aluminum foil 1 can be increased to 2.0 m / min, and the power consumption per unit length can be reduced by 20%. It becomes.

  Further, in the present embodiment, since the water vapor is discharged from the discharge port 7 in the pretreatment mechanism 4, the inside of the main body mechanism 2 is not contaminated with moisture even during long-term operation.

  In addition, as a shape of the discharge port 7, it may be composed of a plurality of continuous openings other than the slit shape described above.

  Further, the main body mechanism 2 and the pretreatment mechanism 4 may be an integrated structure or a separated structure.

DESCRIPTION OF SYMBOLS 1 Aluminum foil, 2 Main body mechanism, 3 Seeds heater, 4 Pretreatment mechanism 5 Far-infrared heater, 6 Washing water, 7 Outlet, 8 Erosion part

Claims (3)

  This is a drying furnace that dries the aluminum foil that has been subjected to the roughening treatment used for aluminum electrolytic capacitors and then dries it. The cleaning water that adheres to the entire surface of the aluminum foil has a radiation wavelength that approximates the maximum absorption wavelength of water. A drying furnace having a far-infrared heater that heats and evaporates with a far-infrared ray.   The drying furnace according to claim 1, wherein water vapor generated by evaporation of cleaning water attached to the surface of the aluminum foil is discharged outside the furnace.   After cleaning the roughened aluminum foil used for aluminum electrolytic capacitors with washing water, the washing water adhering to the surface of the aluminum foil is directly heated by a far-infrared heater having a radiation wavelength that approximates the maximum absorption wavelength of water. The first drying step to evaporate and the second step to evaporate the cleaning water in the erosion part generated by the roughening treatment of the aluminum foil by heating the aluminum foil that has undergone the first drying step by the air drying method A method for drying an aluminum foil.

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