Cover body and method of manufacturing the same

Abstract

The present invention provides a cover body for a sealed battery that has a small number of parts and a relatively simple structure, and can reliably prevent leakage of the electrolyte or intrusion of moisture from the outside, and a method for manufacturing the same. The cover body for sealing a battery container having an opening comprises a terminal member, a sealing plate having a mounting hole for mounting the terminal member, and a resin sealing material for sealing the terminal member by mounting it in the mounting hole of the sealing plate, wherein the terminal member is mounted in the mounting hole of the sealing plate through the sealing material, and the amount of helium leakage in a helium leakage test evaluating the sealability of the sealing material is less than 1.0 × 10⁻⁷ PA·㎥ / sec. Furthermore, the present invention provides a method for manufacturing the cover body by forming the terminal sealing structure by a two-stage injection of molten resin into a cavity to obtain the same by injection molding.

Description

Technology Field

[0001] This invention relates to a cover body and a method for manufacturing the same, and more specifically, to a cover body and a method for manufacturing the same that can obtain a sealed battery having a simple structure and excellent sealability. Background Technology

[0002] Rechargeable batteries, such as lithium-ion batteries that can be repeatedly charged and discharged, are widely used for a wide variety of purposes, including small mobile devices such as mobile phones and laptop computers, transportation vehicles such as automobiles, aircraft, and ships, and power sources for facilities such as factories, buildings, schools, and hospitals.

[0003] Generally, these secondary batteries have an electrode body equipped with a positive electrode and a negative electrode housed in a battery container having an opening and sealed by a cover body. Mounting holes corresponding to the positive and negative electrodes are formed in the cover body, and terminal members are inserted and passed through these mounting holes and connected to lead wires drawn from the electrode body, thereby enabling electrical conductivity between the inside and outside of the battery.

[0004] However, since flammable electrolytes are used in secondary batteries, a cover structure with high airtightness capable of preventing liquid leakage is required for the battery cover.

[0005] For example, Patent Document 1 discloses a cover body (upper cover assembly) of a sealed battery in which an electrode terminal is placed on an electrode extraction hole of an upper cover plate with a sealing ring interposed therebetween, and a ring-shaped fixing member (metal holder) is placed on the electrode terminal and welded to the upper cover plate.

[0006] In addition, Patent Document 2 discloses a cover structure in which a hole is formed in a metal cover body, a seal gasket made of a thermoplastic resin having a tube is inserted from the back side of the cover body, and a metal external terminal is inserted into the tube of the seal gasket, and the inner surface of the hole (hole) of the cover body and the outer surface of the tube of the seal gasket are bonded by laser irradiation, and the inner surface of the tube of the seal gasket and the outer surface of the external terminal are bonded by laser irradiation to firmly seal the cover structure.

[0007] In addition, Patent Document 3 discloses a cover body of a sealed battery in which a terminal member is mounted on a sealing plate having a mounting hole (hole) for mounting a terminal member.

[0008] In the cover body related to this patent document 3, a sealing material is used that includes polyarylene sulfide resin as a thermoplastic resin and additionally includes an inorganic filler with a suppressed volume expansion rate with respect to the electrolyte, and a terminal member is inserted and passed through the mounting hole of the sealing plate with the sealing material bonded to the periphery edge portion. At that time, fine irregularities formed by laser treatment or sandblasting treatment are formed on the contact surface of the terminal member to the sealing material and the contact surface of the sealing plate to the sealing material, respectively, and these contact surfaces are bonded by an anchoring effect. In addition, this sealing material is formed by melting the polyarylene sulfide resin and the inorganic filler and forming the cover body as described above by injection molding. Prior art literature

[0009] Japanese Published Patent Application No. 2021-526707, Japanese Published Patent Application No. 2012-33339, Japanese Published Patent Application No. 2022-103899 The problem to be solved

[0010] As described above, in sealed batteries such as lithium-ion secondary batteries, it is necessary to reliably prevent leakage of the electrolyte, and various cover structures have been examined to date.

[0011] However, in cover structures such as those described in Patent Document 1 or Patent Document 2, the number of parts is large and the number of manufacturing processes increases, so production efficiency is reduced.

[0012] On the other hand, the cover body related to Patent Document 3 has a relatively simple structure without using gaskets such as sealing rings or seal gaskets, but due to the presence of inorganic fillers included in the seal material, an air layer (void) may be formed on the contact surface between the terminal member and the seal material or on the contact surface between the seal plate and the seal material. If moisture (moisture from the air, etc.) is present in such an air layer, there is a risk that toxic hydrogen fluoride may be generated from the electrolyte in the electrolyte (e.g., fluorine-containing compounds such as LiPF6) due to the moisture.

[0013] Therefore, the inventors, after careful consideration to solve the above problem, discovered that a sealing battery cover with excellent sealing properties and a simpler structure than the conventional one can be obtained by forming a sealing material by injection molding in which molten resin is injected into a mold, and by forming a terminal sealing structure in which a terminal member is mounted in a mounting hole of a sealing plate using the sealing material, by forming a terminal sealing structure by a two-stage injection in which molten resin is deliberately discharged into an air vent formed in the mold to form a burr, and then additionally injected molten resin to form a sealing material, thereby completing the present invention.

[0014] Accordingly, the objective of the present invention is to provide a cover body for a sealed battery that has a small number of parts and a relatively simple structure, while reliably preventing leakage of the electrolyte or intrusion of moisture from the outside.

[0015] In addition, another objective of the present invention is to provide a method for manufacturing the above-mentioned cover body. means of solving the problem

[0016] That is, the present invention is a cover body for blocking a battery container having an opening,

[0017] Terminal component and,

[0018] A sealing plate having a mounting hole for mounting a terminal member, and

[0019] A resin sealing material is provided for sealing a terminal member by mounting it in a mounting hole of a sealing plate, and

[0020] In a terminal encapsulation structure in which the terminal member is mounted in the mounting hole of the sealing plate through the above encapsulation material, the amount of helium leakage in a helium leakage test evaluating the sealability by the encapsulation material is 1.0 × 10 -7 It is a cover body characterized by having less than PA·㎥ / sec.

[0021] In addition, the present invention provides a method for manufacturing the cover body for blocking a battery container having an opening, wherein

[0022] In forming a terminal encapsulation structure in which the terminal member is mounted in the mounting hole of the sealing plate through the encapsulation material by arranging the sealing plate and the terminal member within a mold, forming a gap between the mounting hole of the sealing plate and the terminal member, and injecting a molten resin forming the encapsulation material, the terminal member is mounted in the mounting hole of the sealing plate through the encapsulation material.

[0023] The above mold comprises a cavity for forming a sealing material, a gate for injecting molten resin into the cavity, and an air vent for exhausting air at the leading edge in the flow direction of the molten resin injected from the gate and flowing within the cavity.

[0024] A method for manufacturing a cover body characterized by forming a terminal encapsulation structure by a two-step injection process in which molten resin injected into a cavity occupies a portion of the height direction of the air vent, thereby forming a burr and exhausting air to the outside of the mold, and then additionally injecting molten resin into the cavity to form an encapsulation material.

[0025] The cover body in the present invention comprises a terminal member, a sealing plate having a mounting hole for mounting the terminal member, and a resin sealing material for mounting and sealing the terminal member in the mounting hole of the sealing plate, and in a terminal sealing structure in which the terminal member is mounted in the mounting hole of the sealing plate through the sealing material, as shown in the embodiments described below, the amount of helium leakage in a helium leakage test evaluating the sealability by the sealing material is 1.0 × 10 -7 Less than PA·㎥ / sec, preferably 1.0 × 10 -8 It is less than PA·㎥ / sec.

[0026] In the present invention, although not particularly limited, the terminal member may be configured such that its outer diameter is smaller than the inner diameter of the mounting hole of the sealing plate, so that the terminal member is mounted in the mounting hole of the sealing plate through a resin sealing material to form a terminal sealing structure.

[0027] Preferably, the terminal member is to have a flange portion on its outer surface, and likewise, the sealing plate is to have a lip portion on the inner wall surface of the mounting hole. Meanwhile, the sealing material is to have a flange gripping portion that grips the flange portion of the terminal member and a lip gripping portion that grips the lip portion of the sealing plate. By doing so, a more robust terminal sealing structure can be achieved.

[0028] Additionally, the terminal member may have a hydroxyl group-containing film on its outer surface. Likewise, the sealing plate may have a hydroxyl group-containing film on the inner wall surface of the mounting hole. Such a hydroxyl group-containing film can be formed, for example, by laser treatment involving irradiating with laser light. The hydroxyl group-containing film formed by laser treatment is advantageous in that it exhibits an anchoring effect on the resin sealing material due to having surface irregularities. In the case of laser treatment, preferably, the obtained hydroxyl group-containing film can form a hydroxyl group-containing film in which oxygen elements are localized on the surface layer such that the oxygen content measured by EPMA in the surface layer up to a depth of 3 μm from the outermost surface is 0.1 mass% or more and 50 mass% or less.

[0029] In addition to the laser treatment described above, the hydroxyl group-containing film may also be formed using known methods, such as hydration oxide treatment with hot water or hot water, zincate treatment, or chemical treatment containing an organic compound component having hydroxyl groups. Furthermore, the hydroxyl group-containing film varies depending on the type of metal forming the terminal member or sealing plate, and examples include metal hydroxides (metal hydroxides) such as aluminum hydroxide (Al(OH)3), aluminum oxide hydroxide (AlO(OH)), copper hydroxide (Cu(OH)2), iron (II) hydroxide (Fe(OH)2), iron (III) oxide hydroxide (FeO(OH)), or metal oxide hydroxides (metal oxide hydroxides). In addition, the hydroxyl group-containing film may include metal oxides (metal oxides) such as aluminum oxide (Al2O3), copper (I) oxide (Cu2O), copper (II) oxide (CuO), iron (II) oxide (FeO), iron (II, III) oxide (Fe3O4), iron (III) oxide (Fe2O3), etc., depending on the metal forming the terminal member or the sealing plate.

[0030] Regarding the encapsulating material in the present invention, it is not particularly limited as long as it is made of resin, but it is preferable to select one suitable for forming the encapsulating material by injection molding as described below. Among these, it is preferable that it includes polyarylene sulfide resin as a thermoplastic resin. Polyarylene sulfide resin is an insulating resin that has resistance to fluorine-containing compounds or hydrogen fluoride contained in the electrolyte in the electrolyte solution, and can be used as an encapsulating material with excellent chemical resistance, cold and heat resistance, and good moldability in addition to adhesion to metal. The content of polyarylene sulfide resin in the encapsulating material is preferably 50 mass% or more and 100 mass% or less, and preferably 70 mass% or more and 99.9 mass% or less.

[0031] This polyarylene sulfide resin has a structure in which, for example, benzene rings (p-phenylene groups) and sulfur atoms (sulfide bonds) are alternately bonded, similar to polyphenylene sulfide. Specifically, examples include homopolymers or copolymers composed of p-phenylene sulfide units, m-phenylene sulfide units, o-phenylene sulfide units, phenylene sulfide sulfone units, phenylene sulfide ketone units, phenylene sulfide ether units, and biphenylene sulfide units. More specifically, examples include poly(p-phenylene sulfide), polyphenylene sulfide sulfone, polyphenylene sulfide ketone, and polyphenylene sulfide ether. Among these, poly(p-phenylene sulfide) is preferred, particularly due to its excellent heat resistance and strength properties.

[0032] In the present invention, the sealing material may include an acrylic acid ester. In particular, when a hydroxyl group-containing film is provided on the outer surface of a terminal member or on the inner wall surface of a mounting hole in a sealing plate, the carbonyl groups contained in the acrylic acid ester interact with the hydroxyl groups of the hydroxyl group-containing film and adhere to it, thereby suppressing the formation of an air layer at the interface between the sealing material and these surfaces, and thus making it possible to form a cover body with excellent sealing properties.

[0033] Here, regarding the acrylic acid ester included in the packaging material, it is preferable that it be one or more selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, 2-dimethylaminoethyl acrylate, and 2-hydroxyethyl acrylate, from the viewpoint that injection molding is easy and higher adhesion is obtained.

[0034] When a packaging material contains acrylic acid ester and exhibits the above-mentioned effects, it is preferable that the content of acrylic acid ester in the packaging material be 0.1 mass% or more and 10 mass% or less. Since the effect is not confirmed if the content of acrylic acid ester is excessively low, and conversely, the effect becomes saturated if it becomes excessively high, it is desirable to keep the content within the above range, as further effects cannot be expected.

[0035] In addition, in the present invention, the encapsulant may comprise one or more polyolefins selected from the group consisting of polyethylene and polypropylene. By including a polyolefin in addition to the polyarylene sulfide resin, the encapsulant can secure resistance to external impact (impact resistance) as a cover body constituting a sealed battery.

[0036] Regarding this polyolefin, it is preferable that the content in the encapsulating material be 0.1 mass% or more and 20 mass% or less. If the content of the polyolefin is excessively low, there is a risk that the effect will not be sufficiently obtained, and conversely, if it becomes excessively high, further effects cannot be expected and the effect becomes saturated. Within the above range of content, a cover body with excellent impact resistance can be reliably obtained.

[0037] In addition, in the present invention, the encapsulant may contain polydimethylsiloxane (PMDS) as an additive. By including polydimethylsiloxane (PMDS) in the encapsulant, when the encapsulant is formed by injection molding, the fluidity and release properties of the resin composition (which includes a polyolefin or said polydimethylsiloxane as needed) that is injected by injection molding, including at least a polyarylene sulfide resin and an acrylic acid ester, can be increased and processability can be improved.

[0038] In order to achieve such effects, it is preferable that the encapsulant contains 0.2 mass% or more and 9.5 mass% or less of polydimethylsiloxane (PMDS). If the content of polydimethylsiloxane (PMDS) is excessively low, there is a risk that the effect will not be sufficiently obtained, and conversely, if it becomes excessively high, further effects cannot be expected and the effect becomes saturated. Within the above range of content, processability during injection molding can be improved.

[0039] In the present invention, the method for obtaining such a cover body is not particularly limited, but preferably, the method described below may be used.

[0040] That is, in the present invention, a sealing plate and a terminal member are arranged within a mold, and a gap is formed between the mounting hole of the sealing plate and the terminal member, and a molten resin forming a sealing material is injected to obtain a cover body having a terminal sealing structure in which a terminal member is mounted in the mounting hole of the sealing plate through the sealing material. In this case, the mold is provided to have a cavity forming a sealing material, a gate for injecting molten resin into the cavity, and an air vent for exhausting air at the leading edge in the flow direction of the molten resin injected from the gate and flowing within the cavity.

[0041] Then, a terminal encapsulation structure is formed by a two-step injection process in which molten resin injected into the cavity of the mold occupies a portion of the height direction of the air vent, thereby exhausting air to the outside of the mold while forming a burr, and additionally, molten resin is injected into the cavity to form an encapsulation material.

[0042] Generally, in molds used for injection molding, an air vent (gas exhaust port) is formed to connect the inside of the cavity with the outside of the injection molding mold. Then, when molten resin is injected into the cavity (sometimes simply referred to as "injection"), the air originally present in the cavity or the gas generated from the molten resin (collectively referred to as "air") is exhausted to the outside of the mold through the air vent. At that time, if the molten resin is blocked in the air vent, the molten resin cannot flow efficiently within the cavity. Therefore, countermeasures are taken, such as, for example, by reducing the pressure within the cavity using a pressure reduction device, blocking the air vent with a pin or the like before the molten resin reaches the air vent to prevent the molten resin from entering (see Japanese Patent Publication No. 2005-178184), or forming a groove between the cavity and the air vent with a width that prevents the molten resin from flowing in (see Japanese Patent Publication No. 2014-104660).

[0043] In the present invention, during the first stage of the two-stage injection described above, the molten resin injected into the cavity occupies a portion of the height direction of the air vent, and the molten resin is discharged into the air vent to form a burr while exhausting air to the outside of the mold. At this time, the air present in the cavity is extruded by the molten resin flowing through the cavity, but together with the gas contained in the molten resin, the air blown into the molten resin by a fountain flow or the like as the molten resin flows is collected at the leading edge (flow front) in the flow direction. In this way, the molten resin at the leading edge in the flow direction containing a relatively large amount of air (in other words, the molten resin in the flow front portion) is deliberately discharged into the air vent.

[0044] Next, in the second stage of the two-stage injection described above, molten resin is additionally injected into the cavity to form a sealing material. As the skin layer hardens during the first stage of injection, the molten resin is filled into the area where a so-called depression occurs, thereby increasing the density of the molten resin forming the sealing material within the cavity. By forming the sealing material through this two-stage injection, a terminal sealing structure with excellent sealing properties can be obtained.

[0045] In addition, the two-stage injection in the present invention includes, in addition to dividing the injection of the resin into two stages as described above, an embodiment in which the first stage mainly controls the flow rate of the resin injected in injection molding, and the second stage subsequently controls the pressure of the injected resin are performed.

[0046] In the present invention, molten resin injected into the cavity is discharged into the air vent so that the molten resin occupies a portion of the height direction of the air vent, thereby forming a burr in the discharged portion of the molten resin. At that time, if the entire height direction of the air vent is blocked by molten resin, it becomes impossible to exhaust air to the outside of the mold through the air vent. Therefore, the molten resin is discharged so that it occupies a portion of the height direction of the air vent. At that time, the height of the air vent may vary depending on the type of molten resin, so it is difficult to specify it uniformly, but for example, when the resin forming the encapsulating material includes polyarylene sulfide resin, it is preferable that the height of the air vent be greater than 0.06 mm.

[0047] In addition, regarding the burr formed by molten resin leaked into the air vent, its shape is not particularly limited. For example, an annular burr may be formed extending concentrically from the outer periphery of the encapsulating material, or a partial burr may be formed extending from a part of the outer periphery of the encapsulating material. Furthermore, since the burr formed by molten resin leaked into the air vent does not perform any particular function after the terminal encapsulating structure is obtained, the burr may be left as is, but it is preferable to cut it off as it is an unnecessary part.

[0048] Furthermore, according to the present invention, by using a cover obtained in this manner to block the opening of a battery container housing an electrode body having a positive electrode and a negative electrode, a sealed battery with excellent impact resistance can be obtained that reliably prevents leakage of the electrolyte or intrusion of moisture from the outside. In particular, according to the present invention, a sealed battery with excellent sealing properties (airtightness) can be obtained while having a relatively simple structure and a small number of parts, and it is desirable for obtaining a sealed battery such as, for example, a lithium-ion secondary battery. Effects of the invention

[0049] According to the present invention, a cover body with excellent sealing properties (airtightness) is obtained, which has a small number of parts and a relatively simple structure, and can reliably prevent leakage of the electrolyte or the intrusion of moisture from the outside. Furthermore, in the sealed battery obtained by the present invention, in addition to excellent sealing properties, the formation of an air layer in the encapsulating material of the cover body structure can be minimized, thereby reliably eliminating the risk of moisture remaining in the air layer intruding into the battery and mixing into the electrolyte. Brief explanation of the drawing

[0050] FIG. 1 is a schematic plan view for explaining a cover body having a bag material in a state equipped with a burr, FIG. 1(a) shows the surface of the cover body, and FIG. 1(b) shows the back surface of the cover body. Figure 2 is a schematic cross-sectional diagram showing section II of Figure 1(a). FIG. 3 is a schematic plan view illustrating the surface of a cover body having a bag material after removing the burr. Figure 4 is a schematic cross-sectional diagram showing the section II-II of Figure 3. FIG. 5 is a schematic diagram illustrating the manufacture of a cover body using a mold device (a state in which a sealing plate and a terminal member are inserted into a movable mold). FIG. 6 is a schematic diagram illustrating the manufacture of a cover body using a mold device (a state in which molten resin is injected by sealing the mold). FIG. 7 is a schematic diagram illustrating the manufacture of a cover body using a mold device (a state in which the mold is opened and the cover body is removed after cooling). FIG. 8 is a cross-sectional schematic diagram (part) for explaining the appearance of a mold when forming a test bag in an embodiment. FIG. 9 is an explanatory diagram for explaining the adjustment conditions (vent present_modified 1 to 2) of an air vent formed in a mold in an embodiment. FIG. 10 is an explanatory diagram for explaining the adjustment conditions (vents present_3 to 4) of the air vents formed in the mold in the embodiment. FIG. 11 is a schematic diagram illustrating a test bag obtained in an example (in the case of “Vent_1” and “Vent_2”), FIG. 11(a) is a plan view of the test bag, and FIG. 11(b) is a cross-sectional view taken along line III-III of FIG. 11(a). FIG. 12 is a schematic diagram illustrating a test bag obtained in an example (in the case of “Vent_3” and “Vent_4”), FIG. 12(a) is a plan view of the test bag, and FIG. 12(b) is a cross-sectional view taken along line III-III of FIG. 12(a). Specific details for implementing the invention

[0051] The present invention will be described in more detail below with reference to the drawings.

[0052] FIG. 1 shows an example for explaining a cover body obtained by a method related to the present invention, FIG. 1(a) is a schematic plan view showing the surface, and FIG. 1(b) is a schematic plan view showing the back side. The cover body of the present invention comprises a terminal member (1) made of an aluminum electrode and corresponding to a positive electrode, a terminal member (2) made of a copper electrode and corresponding to a negative electrode, a sealing plate (3) made of an aluminum substrate having a mounting hole (3b) for mounting the terminal members (1, 2), and a resin sealing material (4) that seals the terminal members (1, 2) by mounting them in the mounting hole (3b) of the sealing plate (3).

[0053] Also, as shown in FIG. 1(a) and FIG. 2, the resin packaging material (4) has an annular burr (5) formed by extending concentrically from its outer periphery. This annular burr (5) is formed when the packaging material (4) is formed by injection molding as described later, and since it becomes unnecessary when used as a cover body to block the opening of a battery container, the annular burr (5) is finally removed. FIG. 3 shows a schematic plan view of the cover body after the annular burr (5) has been removed.

[0054] And, as shown in FIG. 4, the terminal member (1) (terminal member (2)) has a flange portion (1a) (flange portion (2a)) on each outer circumference, and the seal plate (3) has a lip portion (3a) on the inner wall surface of each mounting hole (3b). Also, FIG. 4 shows the appearance of the terminal member (1) corresponding to the positive electrode, but the same applies to the terminal member (2) corresponding to the negative electrode.

[0055] Additionally, the outer surface of the terminal member (1, 2) is provided with a hydroxyl-containing film formed by laser treatment, including the surface of the flange portion (1a, 2a). Likewise, for each mounting hole (3b) of the sealing plate (3), the inner wall surface is provided with a hydroxyl-containing film formed by laser treatment, including the surface of each lip portion (3a).

[0056] Meanwhile, the sealing material (4) includes polyarylene sulfide resin as a thermoplastic resin and also includes acrylic acid ester, and is provided with a flange-catching portion (4a) that bites the flange portion (1a, 2a) of the terminal member (1, 2) as described above, and also has a lip-catching portion (4b) that bites the lip portion (3a) of the sealing plate (3). At that time, the hydroxyl groups of the hydroxyl group-containing film provided on the outer surface of the terminal member (1, 2) and the carbonyl groups of the acrylic acid ester interact to form a strong bond, and the hydroxyl groups of the hydroxyl group-containing film provided on the inner wall surface of the mounting hole (3b) of the sealing plate (3) interact to form a strong bond.

[0057] In this way, to obtain a terminal seal structure in which terminal members (1, 2) are mounted in the mounting hole (3b) of the sealing plate (3) through the sealing material (4), the sealing plate (3) and the terminal members (1, 2) are placed in a mold, and a gap is formed between the mounting hole (3b) of the sealing plate (3) and the terminal members (1, 2), respectively, and a resin forming the sealing material (4) is injected.

[0058] Here, as the resin forming the packaging material (4), in addition to polyarylene sulfide resin and acrylic acid ester, a resin composition including polyolefin such as polyethylene or polypropylene, or including polydimethylsiloxane as an additive, may be used.

[0059] In cases where the encapsulant comprises an acrylic acid ester and a polyolefin in addition to the polyarylene sulfide resin, these may form an olefin copolymer. Specifically, the copolymer is formed by copolymerizing one or more selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, 2-dimethylaminoethyl acrylate, and 2-hydroxyethyl acrylate with one or more polyolefins selected from the group consisting of polyethylene and polypropylene, and the copolymer is included as an elastomer in the polyarylene sulfide resin.

[0060] In addition, in obtaining a cover body related to the present invention, a mold device having a movable type (6a, 6b) and a fixed type (7) as shown in FIG. 5 may be used. That is, this mold device has a cavity (8) formed by arranging (inserting) a sealing plate (3) and terminal members (1, 2) on the movable type (6a) side, a gate (9) for injecting molten resin into the cavity, and an air vent (10) for exhausting air at the leading end of the flow direction of the molten resin injected from the gate and flowing inside the cavity.

[0061] First, after heating this mold device to about 140 to 160°C, the movable mold (6a, 6b) and the fixed mold (7) are joined as shown in FIG. 6, and then, for example, a resin composition including polyarylene sulfide resin and acrylic acid ester is melted at 300°C or higher and injected.

[0062] At that time, the molten resin is injected by injection in two stages. In the first stage injection, the molten resin (11) injected into the cavity (8) occupies a portion of the height direction of the air vent (10), and the molten resin (11) is discharged into the air vent (10) to form a burr (5), while exhausting air to the outside of the mold device. At this time, as described above, the air present in the cavity (8) is extruded by the molten resin (11) flowing through the cavity (8), but since the air blown in when the molten resin (11) flows is gathered at the leading edge (flow front) of the flow direction along with the gas contained in the molten resin (11), the molten resin at the leading edge of the flow direction containing a relatively large amount of air (in other words, the molten resin in the flow front portion) is discharged into the air vent (11).

[0063] Next, as the second stage of the two-stage injection, additional molten resin (11) is injected into the cavity (8) to form a sealing material (4). By doing so, the molten resin (11) is filled into areas such as the area where a depression occurred during the first stage of injection, thereby increasing the density of the molten resin (11) that forms the sealing material (4) within the cavity (8).

[0064] In addition to the case where the injection of the resin is divided into two stages as described above, for example, in injection molding, the process may be divided into a first stage that mainly controls the flow rate of the resin being injected and a second stage that controls the pressure of the injected resin, thereby allowing the molten resin (11) to flow out into the air vent (10) and exhaust the air to the outside of the mold device while forming a burr (5), and then additionally fill the molten resin (11) to increase the density of the molten resin (11) that forms a sealing material (4) in the cavity (8).

[0065] After cooling the mold device, the mold consisting of a movable type (6a, 6b) and a fixed type (7) is opened as shown in FIG. 7. By doing so, a cover body is formed in the movable type (6a) in which terminal members (1, 2) are mounted with a sealing material (4) in each mounting hole (3b) of the sealing plate (3). However, since the sealing material (4) at that time has a burr (5) as shown in FIG. 1, it is removed as necessary. By doing so, in a terminal sealing structure in which terminal members are mounted in the mounting holes of the sealing plate through the sealing material, the amount of helium leakage in the helium leakage test evaluating the sealability by the sealing material is 1.0 × 10 -7 It is possible to obtain values ​​such as less than PA·㎥ / sec.

[0066] Examples

[0067] The present invention will be described in detail below based on examples, but the present invention is not limited to these contents.

[0068] (Test No. 1 ~ 11)

[0069] An aluminum substrate made of A5052 aluminum alloy with an outer diameter of 55 mm × an inner diameter of 20 mm × a thickness of 2 mm and a central opening was prepared. This aluminum substrate was laser-irradiated on a donut-shaped area with a width of 2 mm on one side surface to surround the central opening. The laser treatment conditions are shown below.

[0070] Laser Treatment Conditions

[0071] · Device: Manufactured by Keyence, 3Axis Fiber Laser Marker (Model: MDF-5200)

[0072] · Laser wavelength: 1090 nm

[0073] · Transmission method: Pulse

[0074] · Output: 42.5 W

[0075] · Frequency: 60 kHz

[0076] · Beam diameter: 60 µm

[0077] · Irradiation interval: 90 µm

[0078] · Scanning speed: 340 mm / s

[0079] · Number of injections (Number of irradiations): 1 time

[0080] · Energy density: 1.45 J / mm²

[0081] A hydroxyl group-containing film was formed by performing laser treatment under the above conditions. Here, regarding the point where laser treatment was performed, from the measurement results by GD-OES, the amount of aluminum detected was 41.8 and the amount of hydroxyl group detected was 3.6 in the range from when the luminescence intensity originating from aluminum and hydroxyl groups was detected until 3.33 seconds, which is required for 200 nm sputtering, had elapsed. The hydroxyl group abundance was calculated to be 7.93.

[0082] Next, as schematically shown in FIG. 8, this aluminum substrate (21) was placed in a mold consisting of a first mold (24) and a second mold (25). At that time, the aluminum substrate (21) was set in the second mold (25) such that the laser processing part (21a), on which laser processing was performed, faced the first mold (24). Here, the first mold (24) has a gate (26) formed for injecting molten resin into the cavity formed when the molds are assembled, and also has an air vent (27) for exhausting air from the leading edge of the flow direction of the molten resin that is injected from the gate (26) and flows through the cavity. In this test, the air vent (27) formed when the molds are assembled was adjusted by changing the width or depth of each groove formed in the first mold (24) and the second mold (25).

[0083] Specifically, as shown in FIG. 9, i) a groove with a width of 5 mm × a depth of 0.03 mm is formed on the outer side of the cavity portion of the first type (24) (the air vent formed at this time is referred to as “vent present_one 1”), and ii) a groove with a width of 5 mm × a depth of 0.03 mm is formed on the cavity portion of the second type (25) (the same “vent present_one 2”), and, as shown in FIG. 10, iii) a groove with a depth of 0.03 mm is formed on the outer circumference of the cavity portion of the first type (24), and a groove with a depth of 0.03 mm is formed along the circumference of the cavity portion of the second type (25) (the same “vent present_one 3”), and iv) the cavity portion of the first type (24) The air vent formed under each condition was adjusted in the case where a groove with a depth of 0.06 mm was formed on the outer circumference (the same “with vent_piece 4”), v) the case where these grooves were not formed in the first type (24) and the second type (25) (the same “without vent”).

[0084]

[0085] Then, using polyarylene sulfide resin (DIC Z-200-E2) as the injection molding resin, molten resin was injected into a mold consisting of a first mold (24) and a second mold (25) by two-stage injection as follows.

[0086] Injection molding was performed using a micro-injection molding machine (Moldlock X-801U manufactured by Century Innovation Co., Ltd.), and the molten resin was injected from the gate (26) of the first mold (24). At that time, the mold temperature and resin temperature were set as shown in Table 1, the maximum filling pressure was set to 6 MP, and the molten resin was injected under the previously described air vent adjustment conditions until the exhaust of air from the air vent (27) ceased. The injection of the molten resin was terminated at the point when the exhaust of air from the air vent (27) could no longer be confirmed.

[0087] Next, the test encapsulated body was removed after sufficient natural cooling with the mold closed (Test No. 2, 5 to 11, 13), or the test encapsulated body was removed by opening the mold immediately after injection molding was completed without undergoing such natural cooling (Test No. 1, 3, 4, 12).

[0088] The test encapsulation obtained above is formed by blocking the opening of an aluminum substrate (21) having an opening in the center with an encapsulation material (22). Among these, the encapsulation material (22) has a disc shape with a height (H) of 0.06 mm and an outer diameter (W) of 20 mm and is firmly bonded to the laser-treated portion (21a) of the aluminum substrate (21). Among these, the test encapsulations of Test No. 2 to 4 obtained in the case of “Vent 1” and “Vent 2” had a burr (23) formed extending from a part of the outer periphery of the encapsulation material (22), as shown in FIG. 11. Also, in the case of “Vent Included_Piece 3” and “Vent Included_Piece 4”, the test bags of Test No. 5 to 11 and 13 had annular burrs (23) formed extending concentrically from the outer periphery of the bag material (22). All of these burrs had a height (t) of about 0.06 mm and a length (d) of about 0.1 to 0.5 mm. Therefore, for each test bag, the length of the burr (length protruding horizontally from the outer periphery of the bag material) (d) was measured, and evaluated in four stages: sufficient burr formed when d = approximately 0.5 mm (Evaluation A), slightly insufficient burr formed when d = 0.1 to 0.2 mm (Evaluation B), insufficient burr formation when d = approximately 0.1 mm (Evaluation C), and no burr formed when d = 0 (Evaluation D). The results are shown in Table 2.

[0089] In addition, a helium leak test to evaluate sealability was conducted on the test bag obtained above as follows. Furthermore, the test was performed after removing all burrs formed on the outer periphery of the bag material.

[0090] [Helium Leak Test]

[0091] That is, in order to evaluate the sealability (airtightness) of the bag material (22) of the test bag, a helium leak test was performed using a helium leak detector (HELIOT 901W1 manufactured by Albaksa). The test bag was set through an O-ring on a lower jig made of SUS304 installed on the helium leak detector, and a helium leak value of 1 × 10 -12 Vacuum was achieved using roughing pumps and turbomolecular pumps until it reached the Pa·㎥ / s range.

[0092] Next, an upper jig made of SUS304 was set over the test bag body through an O-ring, helium (He) gas was injected into the interior of the upper jig, a resin cover was placed over the opening of the upper jig, and the amount of He gas leakage from the opening of the aluminum substrate (21) sealed with the bag material (22) was detected to determine the amount of He gas leakage (helium leakage rate). In addition, for cases where the amount of He gas leakage was detected multiple times, the average value was taken as the amount of He gas leakage (helium leakage). The results are shown in Table 2.

[0093]

[0094] (Test No. 12 ~ 13)

[0095] A copper substrate made of C1020 oxygen-free copper with an outer diameter of 55 mm × inner diameter of 20 mm × thickness of 2 mm and a central opening was prepared. This copper substrate was laser-irradiated on a donut-shaped area with a width of 2 mm on one side surface, surrounding the central opening. The laser treatment conditions are shown below.

[0096] Laser Treatment Conditions

[0097] · Device: Manufactured by Keyence, 3Axis Fiber Laser Marker (Model: MDF-5200)

[0098] · Laser wavelength: 1090 nm

[0099] · Transmission method: Pulse

[0100] · Output: 42.5 W

[0101] · Frequency: 60 kHz

[0102] · Beam diameter: 60 µm

[0103] · Irradiation interval: 90 µm

[0104] · Scanning speed: 400 mm / s

[0105] · Number of injections (Number of treatments): 5 times

[0106] · Energy density: 5.9 J / mm²

[0107] A hydroxyl group-containing film was formed by performing laser treatment under the above conditions. Here, regarding the point where laser treatment was performed, from the measurement results by GD-OES, the amount of detected copper was 38.2 and the amount of detected hydroxyl group was 2.6 in the range from when the luminescence intensity originating from copper and hydroxyl groups was detected until 1.25 seconds, which is required for 200 nm sputtering, had elapsed. The hydroxyl group abundance was calculated to be 6.37.

[0108] Test bags related to Tests No. 12 and 13 were obtained in the same manner as in Tests No. 1 to 11, except that the copper substrate mentioned above was used. In addition, for the obtained test bags, the appearance of burrs was evaluated and the amount of helium leakage was measured in the same manner as in the previous case. The results are shown in Table 2.

[0109] From the results shown in Table 2, it can be seen that the degree of burr formation appearing on the outer periphery of the packaging material is correlated with the amount of He gas leakage (helium leakage). That is, while the amount of helium leakage increased uniformly in test packaging materials where burr formation could not be confirmed (Test Nos. 1 and 12) and insufficient burr formation, in test packaging materials where burr formation on the outer periphery of the packaging material was sufficient (Test Nos. 9–11 and 13), the amount of helium leakage was 1.0 × 10⁻⁶. -7 It was less than PA·㎥ / sec.

[0110] That is, according to the present invention, a cover body with excellent sealability (airtightness) is obtained. In particular, according to the method of the present invention, by forming a sealing material by two-step injection, the density of the resin forming the sealing material can be increased and a terminal sealing structure with excellent sealability can be obtained, so a cover body can be realized that has a relatively simple structure with fewer parts and can reliably prevent leakage of the electrolyte or intrusion of moisture from the outside. Explanation of the symbols

[0111] 1, 2: Terminal absence 1a, 2a: Flange section 3 : Bonggupan 3a : Lip part 3b : Mounting hole 4 : Resin bagging material 5 : Bur 6 (6a, 6b) : Movable type 7 : Fixed type 8 : Cavity 9 : Gate 10: Air vent 11: Molten resin 21 : Aluminum substrate 21a: Laser processing unit 22 : Bag material 23 : Bur 24: Type 1 25 : Type 2 26 : Gate 27 : Air vent

Claims

Claim 1 A cover body for sealing a battery container having an opening, comprising a terminal member, a sealing plate having a mounting hole for mounting the terminal member, and a resin sealing material for sealing the terminal member by mounting it in the mounting hole of the sealing plate, wherein the terminal member is mounted in the mounting hole of the sealing plate through the sealing material, and the amount of helium leakage in a helium leakage test evaluating the sealability of the sealing material is 1.0 × 10 -7 A cover body characterized by being less than PA·㎥ / sec. Claim 2 A cover body according to claim 1, wherein the outer diameter of the terminal member is smaller than the inner diameter of the mounting hole of the sealing plate. Claim 3 A method for manufacturing a cover body according to claim 1, wherein the sealing plate and the terminal member are placed within a mold, a gap is formed between the mounting hole of the sealing plate and the terminal member, and a molten resin forming the sealing material is injected to form a terminal sealing structure in which the terminal member is mounted in the mounting hole of the sealing plate through the sealing material, wherein the mold comprises a cavity forming the sealing material, a gate for injecting the molten resin into the cavity, and an air vent for exhausting air at the leading edge in the flow direction of the molten resin injected from the gate and flowing within the cavity, and wherein the molten resin injected into the cavity occupies a portion of the height direction of the air vent, thereby exhausting air to the outside of the mold while forming a burr, and subsequently, additionally, the molten resin is injected into the cavity to form the sealing material, thereby forming a terminal sealing structure by a two-stage injection. Claim 4 A method for manufacturing a cover body according to claim 3, cutting a burr made of molten resin leaked into an air vent. Claim 5 A method for manufacturing a cover body according to claim 3, wherein the height of the air vent formed in the mold is greater than 0.06 mm. Claim 6 A method for manufacturing a cover body according to claim 3, wherein the burr formed by molten resin leaked into the air vent is an annular burr formed by extending concentrically from the outer periphery of the bag material, or a partial burr formed by extending to a part of the outer periphery of the bag material. Claim 7 A method for manufacturing a cover body according to claim 3, wherein the packaging material comprises polyarylene sulfide resin as a thermoplastic resin and also contains 0.1 mass% or more and 10 mass% or less of acrylic acid ester. Claim 8 A method for manufacturing a cover body according to claim 3, wherein the acrylic acid ester is one or more selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, 2-dimethylaminoethyl acrylate, and 2-hydroxyethyl acrylate. Claim 9 A method for manufacturing a cover body according to claim 3, wherein the packaging material further comprises one or more polyolefins selected from the group consisting of polyethylene and polypropylene. Claim 10 A method for manufacturing a cover body according to claim 9, wherein the above-mentioned encapsulating material contains 0.1 mass% or more and 20 mass% or less of a polyolefin. Claim 11 A method for manufacturing a cover body according to claim 3, wherein the above-mentioned packaging material further contains polydimethylsiloxane as an additive.

Images