JP2005032669A - Electrode terminal for sealing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode terminal 3 for a sealing plate equipped with a surface state with an improved jointing property so as to exert an excellent sealing performance, by concretely defining the surface state of the electrode terminal 3 effective in improving a jointing property as well as a sealing property between a sealing plate main body 2 and the electrode terminal 3. <P>SOLUTION: Of the electrode terminal 3 for the sealing plate integrated with the sealing plate main body made of a polymer material by insertion molding with a chemical treatment given on a whole or a part of at least a position out of its surface in contact with the sealing plate main body 2, a size of surface roughness on the electrode terminal 3 surface where the chemical treatment is applied is to be Ra 0.05 μm or more, or preferably, Ra 0.1 μm or more, and a diameter of a concave part formed on the electrode terminal 3 surface by the chemical treatment is to be ψ 4μm or more at the maximum and ψ 1 μm or more in the average. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pressure vessel that accommodates a battery element, an electrolyte, or the like in an electronic component such as a battery (including a primary battery and a secondary battery) and a capacitor (including an electrolytic capacitor, an electric double layer capacitor, and a capacitor). The present invention relates to an electrode terminal in a sealing plate used for closing the opening of the sealing member, and relates to an electrode terminal in a sealing plate made of a polymer material. The sealing plate of the present invention is used for, for example, a capacitor or a capacitor as an in-vehicle auxiliary power source, a stationary fuel cell, an inverter capacitor, a condenser for wind power generation, or the like.

  Conventionally, a sealing plate used as a lid for closing an opening of a pressure vessel such as a battery or a capacitor, wherein a sealing plate is formed by integrating an electrode terminal made of aluminum with a sealing plate body made of phenol resin by insert molding. Are known. In this kind of sealing plate, not only the opening of the pressure vessel but also the sealing plate main body and the electrode terminal so that the contents and generated gas inside the pressure vessel do not leak outside after the opening is closed. A sufficient bonding property or sealing property is also required between the two.

  Therefore, the applicant of the present application previously integrally formed the annular flange 4 on the outer peripheral surface 3a of the cylindrical electrode terminal 3 that is vertically attached to the sealing plate body 2 as shown in FIG. Then, a sealing plate 1 having a structure in which an annular engagement groove 5 is formed on at least one of the upper surface and the lower surface of the flange portion 4 and the flange portion 4 is embedded in the sealing plate body 2 has been proposed (see Patent Document 1). ). According to the sealing plate 1, the flange portion 4 in which the engagement groove 5 is formed is embedded in the thickness of the polymer material of the sealing plate body 2, and the polymer material is in close contact with the flange portion 4. In addition, it is possible to improve the bondability between the sealing plate body 2 and the electrode terminal 3, and thereby, the electrolyte solution, the generated gas, etc. leak from the gap between the sealing plate body 2 and the electrode terminal 3. It can be effectively prevented.

  However, in recent years, for example, the use of capacitors has been studied for use in vehicles, and accordingly, the bonding property or sealing property between the sealing plate main body 2 and the electrode terminal 3 has become more severe than ever. The correspondence of is coming. Therefore, the invention described in Patent Document 1 needs to be further improved to meet this new need.

  In the capacitor terminal plate formed by resin-molding a metal terminal, the invention relates to a capacitor terminal plate having a roughened portion formed by chemical treatment on the outer peripheral surface of at least the resin-molded portion of the metal terminal. Although disclosed (see Patent Document 2), this Patent Document 2 only describes that the surface of the metal terminal is roughened in order to improve the bonding property or sealing property between the sealing plate body and the electrode terminal. However, there is no specific data indicating how much the bondability or sealability has improved, and there is no specific description of how the condition of the roughened surface is defined to achieve that purpose. It has not been. Therefore, according to the present invention, it is still unclear what the state of the roughened portion is effective for improving the joining property or the sealing property. There is no place to present technically rudimentary ideas. Further, the details of the invention described in Patent Document 2 are that the surface treatment process of the metal terminal is performed by degreasing and removing the oxide film by immersing the metal terminal in an alkaline aqueous solution, and then immersing the electrode terminal in the acid aqueous solution. Therefore, there is an inconvenience that the number of steps (number of steps) is large.

Japanese Utility Model Publication No. 6-21222 JP 2001-237143 A

  In view of the above points, the present invention improves the bonding property between the sealing plate body and the electrode terminal or the sealing property between them even in a harsh thermal environment than ever, in comparison with the invention described in Patent Document 1. It aims at providing the electrode terminal for sealing boards which can be made to be made. In addition, for the invention described in Patent Document 2, the state of the roughened portion effective for improving the bonding property between the sealing plate body and the electrode terminal or the sealing property between the two is specifically defined, Therefore, it aims at providing the electrode terminal for sealing plates provided with the roughening part which can exhibit the outstanding joining property thru | or sealing performance.

  In order to achieve the above object, an electrode terminal for a sealing plate according to claim 1 of the present invention is an electrode terminal integrated by insert molding into a sealing plate body made of a polymer material, and at least the sealing member on the surface thereof In the electrode terminal for a sealing plate in which all or part of the portion in contact with the plate body is chemically treated, the surface roughness of the surface of the electrode terminal subjected to the chemical treatment is set to Ra 0.05 μm or more. In addition, the diameter dimension of the recess formed on the surface of the electrode terminal by the chemical treatment is at most φ4 μm or more and on average φ1 μm or more.

  The electrode terminal for a sealing plate according to claim 2 of the present invention is preferably the surface roughness of the surface of the electrode terminal subjected to the chemical treatment in the electrode terminal for a sealing plate according to claim 1 described above. Ra is set to 0.1 μm or more.

  According to such a surface state of the electrode terminal, since the so-called anchor effect is exhibited by the concave portion formed by the surface roughening treatment, this is a cause of more firmly joining the sealing plate body and the electrode terminal. can do.

  The present invention has the following effects.

  That is, according to the electrode terminal for a sealing plate according to the first aspect of the present invention having the above-described configuration, the surface roughness of the surface of the electrode terminal is set to Ra 0.05 μm or more and formed by surface roughening treatment. Since the diameter dimension of the concave portion is at least φ4 μm or more and on average φ1 μm or more, the bondability between the sealing plate body and the electrode terminal actually required in the practical area of the electrode terminal or sealing plate is improved. A sufficient sealing property between the two can be ensured.

  In addition, as described above, the invention described in Patent Document 1 provides a sealing plate having excellent sealing performance by adopting an electrode terminal having an annular flange on the outer peripheral surface in the sealing plate in which the electrode terminal is insert-molded. Although it was possible, further improvements would be required in light of the recent severe conditions of use. Accordingly, in the electrode terminal for a sealing plate according to claim 2 of the present invention, the surface of the electrode terminal before molding the sealing plate is subjected to a surface roughening treatment, and further the size of the surface roughness of the electrode terminal surface after the surface roughening treatment. By making Ra preferably 0.1 μm or more, in addition to the effect of the first aspect, it is possible to find an excellent surface state of the electrode terminal capable of reducing the variation in adhesiveness with the sealing plate body material. It was. Therefore, according to the prior art, there is no problem in the initial state before use with respect to harsh use conditions, but there was a risk of electrolyte leakage in long-term use under harsh conditions. Fully possible.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a plan view of a sealing plate 1 provided with an electrode terminal 3 according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view taken along line AA in FIG. The figure is shown.

  The sealing plate 1 according to this embodiment has a sealing plate body 2 and an electrode terminal 3 and is configured as follows.

  That is, first, an electrode terminal 3 made of a metal material is inserted, and the sealing plate body 2 is formed into a plate shape by a polymer material. The electrode terminal 3 penetrates the sealing plate body 2 in the thickness direction. It is buried in. Moreover, the breather part 6 may be provided in one place on the plane of the sealing board main body 2 as a pressure release structure for releasing the pressure inside a pressure vessel, for example.

(1) Sealing plate body 2
The sealing plate main body 2 is formed into a plate shape by a polymer material, for example, a disk shape, an ellipse shape, or a substantially square shape. Examples of the material include a resin material such as a polyolefin resin, a metallocene. Polyolefin resin polymerized by catalyst, polyphenylene sulfide, syndiotactic polystyrene, polyamide resin, polyester resin, polyimide resin, polyamideimide resin, thermoplastic resin such as liquid crystalline resin, phenolic resin, epoxy resin And thermosetting resins such as imide resins, fillers / reinforcing materials such as fibrous fillers such as glass fibers, carbon fibers or whiskers, particulate fillers such as carbon particles, mica and glass beads, metal Oxides or processing aids are appropriately blended. In this example, a phenol resin composition was used as the polymer material.

(2) Electrode terminal 3
An annular flange 4 is integrally formed on the outer peripheral surface 3a of the cylindrical electrode terminal 3. An axial end face of the flange 4 is one or both of the upper and lower surfaces in the figure (see FIG. In both cases, the required number of annular engaging grooves 5 are formed concentrically (two on the upper surface and one on the lower surface in the figure). Further, an external terminal connection portion 7 made of a female screw or the like for connecting an external terminal (not shown) is provided on the outer end surface 3 b of the electrode terminal 3. Is provided with an internal wiring connecting portion 8 made of a caulking projection or the like for connecting an internal wiring (not shown). In general, two electrode terminals 3 are integrated into the sealing plate body 2 as a pair, but any number of electrode terminals 3 may be provided in the sealing plate body 2.

  The material of the electrode terminal 3 is a molding material such as pure aluminum or an aluminum alloy in the case of an aluminum electrolytic capacitor, but is formed of a metal molding material such as zinc, iron, or nickel in a battery. In the present embodiment, 99.0% or more of high-purity aluminum was used as the material of the electrode terminal 3.

  Moreover, although the electrode terminal 3 is produced by machining, any processing means may be used, for example, any cutting process may be used.

  The configuration described above is basically the same as the prior art described in Patent Document 1 described above. According to the above configuration, the electrolyte, generated gas, and the like are generated from the gap between the sealing plate body 2 and the electrode terminal 3. It is possible to effectively prevent leakage. However, if a capacitor is used for in-vehicle applications or the like and is required to cope with a severe thermal environment, there is a concern that the bonding property or sealing property between the sealing plate body 2 and the electrode terminal 3 may be insufficient depending on the situation. The electrode terminal 3 according to the embodiment has been improved in the following points.

  That is, the entire surface of the electrode terminal 3 in contact with the sealing plate body 2, that is, the outer peripheral surface 3a of the electrode terminal 3, the surface of the flange 4 and the inner surface of the engagement groove 5 is subjected to chemical treatment, The surface roughness is specified to be Ra 0.05 μm or more, preferably Ra 0.1 μm or more, and the diameter of the recess formed by the treatment is specified to be a maximum of 4 μm or more and an average of 1 μm or more. . This has been found from the results of the following tests as a result of diligent research by the present inventors.

Test process (1) A large number of electrode terminals with variously modified surface roughening treatment conditions (treatment time, aqueous solution temperature, aqueous solution concentration, additives, etc.) are prepared.
(2) Using the electrode terminals prepared in (1) above, a large number of test pieces of the sealing plate are produced by the same molding method (insert molding with a molding die) as in practice.
(3) Using each test piece produced in the above (2), the tensile test is carried out, and the breaking stress or the fracture surface resin residual ratio at the joint surface of the sealing plate body and the electrode terminal is measured or calculated. Here, the resin refers to the molding material of the sealing plate body, and the fracture surface resin residual ratio indicates a value obtained by measuring and calculating the residual ratio of adhesion to the electrode terminal surface in the measurement region.
(4) The surface state of the electrode terminal (the size of the surface roughness, the diameter of the recess formed by the surface roughening treatment) in each test piece subjected to the tensile test of (3) above is measured and calculated.
(5) The relationship between the tensile test result in (3) and the electrode terminal surface state in (4) is confirmed.

In addition, the definition of the term used by this-application specification is as follows.
a. Surface Roughness The surface of the electrode terminal was magnified with a laser microscope, and the roughness in the measurement region was determined three-dimensionally using a surface instead of a line. Ra represents the surface roughness and is defined by JIS standards, and represents the arithmetic average roughness of the previously obtained values (measurement area≈200 × 300 μm).
b. Diameter of recesses formed by surface roughening treatment: Maximum Enlarge the surface of the electrode terminal with a laser microscope and check all the diameters of recesses formed by surface roughening treatment confirmed in the measurement area. The diameter is shown (measurement area≈200 × 300 μm).
c. Concave diameter formed by surface roughening treatment: average The surface of the electrode terminal was enlarged by a laser microscope, and the diameters of all concave portions formed by surface roughening treatment confirmed in the measurement region were confirmed. (Measurement area≈200 × 300 μm).
d. Residual ratio of fracture surface resin After the above tensile test, the fracture surface of the product after the test is enlarged with an optical microscope, and the area of the material (resin) of the sealing plate body remaining on the fracture surface of the electrode terminal is obtained. It is obtained by calculating a ratio to the entire area of the cross section.

  When the results of the tensile test are summarized by the relationship between the breaking stress and the fracture surface resin residual ratio, as shown in the graph of FIG. 3, the fracture surface resin residual ratio reaches a certain region when the fracture stress exceeds a certain level. I found out. In addition, it was found that 80% or more is a standard for the area of the fracture surface residual resin ratio showing strong bondability (adhesiveness).

  Samples with a fracture surface residual resin ratio of 80% or more can be assumed to have almost good adhesion across the entire fracture surface, but samples with a fracture surface resin residual ratio of less than 80% are clearly broken. It is considered that a part with low adhesiveness was present in a part of the cross section. If such a low adhesive state is replaced with a sealing plate, even if the sealing property is ensured in the initial state, a long period of use under severe thermal conditions will cause the sealing plate body and the electrode terminal to be It is considered that some electrolytes permeate at the interface and the range gradually widens, causing leakage of the electrolyte.

  Therefore, in order to confirm the relationship between such a low adhesive state and the sealing property of the sealing plate, electrode terminals having various surface roughness Ra as shown in FIG. A sealing plate was actually produced using and a sealing property confirmation test was performed as follows. As shown in Fig. 5-2, the number of test samples is 10 with the surface roughness in each surface roughness range, and the sealability confirmation test is as follows: A: Helium leak under each thermal stimulation condition Test, B: Performed in the order of the color check method.

Sealability confirmation test ...
Thermal stimulation condition High temperature and long time: 180 ° C x 1000Hr
Cooling cycle: −40 ° C. × 1 Hr + 150 ° C. × 1 Hr 100 cycle sealing property confirmation method A: Helium leak test Test method: Check for liquid leakage from the interface between the sealing plate body 2 and the electrode terminal 3.
Test jig: A test jig 21 shown in FIG. 4 is used. Reference numeral 1 in the figure indicates a sealing plate as a test sample. This sealing plate 1 is set in the casing 22 of the test jig 21, and helium gas is supplied from the helium gas supply side to one space 23 in the casing. Supply at a pressure of. On the other hand, the other space 24 side in the casing is evacuated by a vacuum pump, and when the helium gas leaks from the one space 23 to the other space 24, this is detected by the leak detector 25.
Jig internal pressure: 0.4 MPa
Pressurization time: 3 min
Determination method: When helium is detected, it is determined that there is a liquid leak. B: Color check method Test method: Check whether there is a gap at the interface between the sealing plate body 2 and the electrode terminal 3. Specifically, after applying an osmotic solution to the interface between the sealing plate body 2 and the electrode terminal 3 and holding it for several minutes, the osmotic solution is wiped off and a developer is applied to the location where the osmotic solution is applied.
Judgment method: When color development is confirmed, it is judged that there is a gap.

  The test results are as shown in the table of FIG. 5-1, and the electrode terminal surface roughness Ra corresponding to a fracture surface resin residual ratio of 80% or more is 0.05 μm or more, preferably 0.1 μm or more. It was confirmed that the sealing plate had good sealing properties even after heat stimulation. Further, as can be seen from this test result, when the fracture surface residual resin ratio is less than 80% (electrode terminal surface roughness Ra is less than 0.05 μm), even if the sealing property is secured in the initial state, the adhesive property At low locations, electrolyte penetration may occur at the interface between the sealing plate body and the electrode terminals due to long-term use due to severe thermal conditions.In this case, the range gradually increases and electrolyte leakage occurs. It is thought that there are things that have come.

  On the other hand, when the surface of the electrode terminal after the surface roughening treatment was observed, as shown in the graph of FIG. 6, depending on the surface roughening treatment conditions of the electrode terminal, the surface roughness ( It was found that Ra) and the size of the recesses formed were also different. In addition, some of the recesses have a hole shape formed independently, and some have a plurality of holes connected to form a stripe shape, and the recess here refers to the case of this hole shape and the stripe shape. And both cases are included. In addition, since the shape of the striped recess is complicated and irregular, it is difficult to appropriately define the size of the recess as defined in the terms b and c in the definition section of the above term. Does not stipulate.

  Summarizing the above matters by the relationship between the surface roughness of the electrode terminal and the residual ratio of the fracture surface resin, as shown in the graph of FIG. 7, the surface roughness of the electrode terminal is set to Ra 0.05 μm or more by the surface roughening treatment. As a result, it was found that the fracture surface resin residual ratio had a small variation and could be stably secured at 80% or more. Furthermore, when the surface roughness of the electrode terminal is Ra 0.1 μm or more, the variation in the fracture surface resin residual ratio is further reduced, so that the fracture surface resin residual ratio of 80% or more can be secured more stably. It was also found that the size of the recesses formed at this time was a maximum φ4 μm or more and an average φ1 μm or more.

  In addition, the procedure of the surface roughening process in a present Example is as follows.

  The electrode terminal 3 is chemically roughened with an alkaline aqueous solution to form a recess on the surface. As for the alkaline aqueous solution, for example, a solution of sodium hydroxide in a solid state or an aqueous solution state is diluted with pure water or pure water adjusted to a constant temperature, and adjusted to a constant concentration, and then roughened. Is carried out, for example, by immersing the electrode terminal 3 in an alkaline aqueous solution for a predetermined time while stirring.

The degree of roughening is as shown in the following (A) and (B). If this degree of roughening can be realized, the conditions for the surface roughening treatment are treatment time, aqueous solution temperature, aqueous solution concentration, additive. Any combination such as addition of the above is allowed. Further, the degree of roughening is determined for each specification of the electrode terminal 3 in order to maintain the dimensional accuracy of each part of the electrode terminal 3, particularly the screw part (external terminal connection part 7). Furthermore, since the anchor effect cannot be expected even if the surface roughening treatment is performed excessively, the processing time is increased and the processing cost is increased. Therefore, the degree of the surface roughening treatment is appropriately determined.
(A) Surface roughness: Ra 0.05 μm or more, preferably 0.1 μm or more (B) Concave diameter formed by surface roughening treatment: maximum φ4 μm or more, average φ1 μm or more

  After the above processing, the electrode terminal 3 is sufficiently washed with water and further sufficiently dried. Then, after the electrode terminal 3 having been subjected to the above surface roughening treatment is inserted and fixed in the cavity of the molding die, the molding material of the sealing plate body 2 is poured into the die by molding means such as transfer or injection. Then, the sealing plate body 2 is formed.

  In addition, about the surface roughening processing method, although alkaline aqueous solution was used in the said Example, if the surface of the electrode terminal 3 can be made into predetermined | prescribed roughness, it will not be this limitation.

The top view of the sealing board provided with the electrode terminal which concerns on the Example of this invention It is an AA line expanded sectional view in Drawing 1, and is a longitudinal cross-sectional view of an electrode terminal The figure which shows the result of the test done when prescribing | regulating the magnitude | size of the surface roughness in this invention, and the diameter dimension of the recessed part by roughening, and is a graph which shows the relationship between a breaking stress and a fracture surface resin residual ratio Illustration of test jig Table showing the sealing performance test results of the sealing plate Table showing sample surface roughness data FIG. 6A is a diagram showing the results of a test performed when defining the size of the surface roughness and the diameter of the concave portion by the surface roughening in the present invention, and FIG. 6A shows the surface roughness by changing the surface roughening treatment conditions. FIG. 6B is a graph showing the change in the size of the recess due to the change in the roughening treatment condition. FIG. 7A is a diagram showing the results of a test conducted when defining the size of the surface roughness and the diameter of the recesses by roughening in the present invention. FIG. 7A shows the relationship between the surface roughness and the residual ratio of the fracture surface resin. FIG. 7 (B) is a detailed view of part B in FIG. 7 (A). Longitudinal longitudinal sectional view of a sealing plate according to a conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing plate 2 Sealing plate main body 3 Electrode terminal 3a Outer peripheral surface 3b Outer end surface 3c Inner end surface 4 Gutter part 5 Engaging groove 6 Breather part 7 External terminal connection part 8 Internal wiring connection part 21 Test jig 22 Casing 23, 24 Space 25 Leak detector

Claims (2)

An electrode terminal (3) integrated with a sealing plate body (2) made of a polymer material by insert molding, and at least a part of the surface thereof contacting the sealing plate body (2) In the electrode terminal (3) for the sealing plate subjected to chemical treatment,
The surface roughness of the surface of the electrode terminal (3) subjected to the chemical treatment is set to Ra 0.05 μm or more, and the diameter dimension of the recess formed on the surface of the electrode terminal (3) by the chemical treatment is increased. An electrode terminal for a sealing plate, characterized in that the maximum is φ4 μm or more, and the average is φ1 μm or more. The electrode terminal for a sealing plate according to claim 1,
An electrode terminal for a sealing plate, characterized in that the surface roughness of the surface of the electrode terminal (3) subjected to the chemical treatment is preferably Ra 0.1 μm or more.

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