Electrode for high-frequency dielectric heating

Abstract

To provide an electrode for high frequency dielectric heating which can reduce the possibility that a surface layer portion of a resin tubular film is peeled off and the opening fails when a sealing portion of the film is cut and opened.SOLUTION: An electrode 20 for high frequency dielectric heating for forming an envelope-attached tubular film 100 by performing high-frequency dielectric heating across a first region P1 and a second region P2 in a state in which the first region P1 and the second region P2 of a laminated film P formed by stacking two vinylidene chloride resin films F are arranged and stacked on the outer side in the radial direction and the inner side in the radial direction, respectively, includes an external electrode 21 arranged radially outside the first region P1, and an internal electrode 22 arranged radially inside the second region P2, and a coating 21A made of an electrical insulator is formed on the external electrode 21.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electrode for high-frequency dielectric heating.

Background Art

[0002] Currently, various cylindrical packages made of resin films for packaging contents such as sausages have been proposed. For example, by joining the inner surfaces of both edge portions of a film rolled into a cylindrical shape in a clasped state, a cylindrical casing portion and a seal portion protruding radially outward from the casing portion and extending in the longitudinal direction are formed, and the seal portion is folded down and welded together with the casing portion to join them, thereby forming a cylindrical package (see Patent Document 1). In recent years, a technique has been proposed in which a seal portion formed by joining both edge portions of a film is made of a specific material to achieve both easy-openability and retort resistance (see Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the technologies described in Patent Document 1 and Patent Document 2, so-called high-frequency welding may be employed, in which a portion to be sealed is sandwiched between electrodes and heated by applying an electric field to weld the portion. When such high-frequency welding is employed, when cutting the sealed portion to open the package, there is a possibility that only the surface layer portion (the portion located most outside in the radial direction) of the film is peeled off and the opening fails. That is, a conventional package (cylindrical film) is formed by stacking four resin films by arranging two laminated films each composed of two resin films on the outside in the radial direction and the inside in the radial direction, and welding all four films to form a sealed portion. Therefore, when cutting the sealed portion to open the package, many cases have occurred in which only the two films on the outside in the radial direction (the surface layer portion located most outside in the radial direction and likely to be stressed) are peeled off and the opening fails. For this reason, an improved high-frequency welding technology for reducing the possibility of opening failure has been demanded, and in particular, the development of electrodes for high-frequency dielectric heating has been eagerly awaited.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide an electrode for high-frequency dielectric heating capable of reducing the possibility that the surface layer portion of the film is peeled off and the opening fails when cutting and opening the sealed portion of a resin cylindrical film.

Means for Solving the Problems

[0006] To achieve the above object, the electrode for high-frequency dielectric heating according to the present invention is for forming a cylindrical film in an envelope-pasting form by performing high-frequency dielectric heating with the first region and the second region of a laminated film formed by stacking two vinylidene chloride-based resin films on each other arranged on the outside and inside in the radial direction and overlapped, sandwiching the first region and the second region. It includes an external electrode arranged outside the first region in the radial direction and an internal electrode arranged inside the second region in the radial direction, and a film made of an electrical insulator is formed on the external electrode. As the electrical insulator, one or more inorganic electrical insulators selected from ceramics, mica, and glass can be employed.

[0007] When adopting such a configuration, in a state where the first region and the second region of a laminated film composed of two layers of vinylidene chloride resin films are arranged and overlapped with the first region on the outer side in the radial direction and the second region on the inner side in the radial direction, high-frequency dielectric heating is performed by sandwiching the first region and the second region with an external electrode arranged on the outer side in the radial direction more than the first region and an internal electrode arranged on the inner side in the radial direction more than the second region, and the first region and the second region are continuously welded to form a tubular film in the form of a sealed envelope capable of filling and sealing various contents (such as ground meat, etc.). At this time, since a film made of an electrical insulator is formed on the external electrode, the region where the temperature between the electrodes is the highest can be shifted to the external electrode side. Therefore, two films constituting the first region arranged on the outer side in the radial direction and one film located on the outer side in the radial direction among the two films constituting the second region arranged on the inner side in the radial direction can be welded to form a seal portion. That is, since a seal portion can be formed by welding three out of the four films from the outside, when cutting the seal portion to open the package, peeling of the film located on the outer side in the radial direction among the two films constituting the first region arranged on the outer side in the radial direction from the film located on the inner side in the radial direction can be prevented. As a result, the possibility of opening failure can be reduced.

[0008] In the electrode for high-frequency dielectric heating according to the present invention, the line roughness of the portion of the external electrode in contact with the vinylidene chloride resin film can be set to a maximum height Rz100 (μm) or less and an arithmetic mean roughness Ra10 (μm) or less.

[0009] When such a configuration is adopted, since the line roughness of the portion of the external electrode that contacts the vinylidene chloride resin film is set to a maximum height Rz100 (μm) or less and an arithmetic mean roughness Ra10 (μm) or less, the frictional resistance between the electrode and the film can be reduced, and for example, continuous welding at a film speed of 30 to 40 m / min can be realized. That is, by setting the line roughness of the said portion to a maximum height Rz100 (μm) or less and an arithmetic mean roughness Ra10 (μm) or more, it is possible to prevent a situation in which the frictional resistance between the electrode and the film increases and the film pulsates.

[0010] In the electrode for high-frequency dielectric heating according to the present invention, the line roughness of the portion of the external electrode that contacts the vinylidene chloride resin film can be set to a maximum height Rz1 (μm) or more and an arithmetic mean roughness Ra0.5 (μm) or more.

[0011] When such a configuration is adopted, since the line roughness of the portion of the external electrode that contacts the vinylidene chloride resin film is set to a maximum height Rz1 (μm) or more and an arithmetic mean roughness Ra0.5 (μm) or more, the slipperiness with the film can be appropriately exhibited. That is, by setting the line roughness of the said portion to a maximum height Rz1 (μm) or more and an arithmetic mean roughness Ra0.5 (μm) or more, it is possible to prevent a situation in which the film becomes too smooth, the slipperiness with the film deteriorates, the frictional resistance increases, and the film pulsates.

[0012] In the electrode for high-frequency dielectric heating according to the present invention, the thickness of the coating can be set to 10 μm or more and 150 μm or less.

[0013] By adopting such a configuration, it is possible to more surely weld three out of the four vinylidene chloride resin films from the outside to form a seal portion. That is, by setting the thickness of the coating to 10 μm or more, the region where the temperature between the electrodes is the highest can be sufficiently shifted to the external electrode side. Therefore, it is possible to prevent a situation where the two films constituting the first region arranged on the outer side in the radial direction and the two films constituting the second region arranged on the inner side in the radial direction are welded and the sealability cannot be ensured. Further, by setting the thickness of the coating to 150 μm or less, it is possible to prevent a situation where the output for welding becomes too large and a spark is generated due to minute fluctuations in the film.

[0014] In the electrode for high-frequency dielectric heating according to the present invention, the thickness of the coating can be set to 40 μm or more and 90 μm or less.

[0015] By adopting such a configuration, it is possible to more surely weld three out of the four vinylidene chloride resin films from the outside to form a seal portion.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide an electrode for high-frequency dielectric heating that can reduce the possibility of the surface layer portion of the film peeling off and resulting in a sealing failure when cutting and opening the seal portion of the resin tubular film.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are merely preferred application examples, and the scope of application of the present invention is not limited thereto.

[0019] First, with reference to FIGS. 1 and 2 and the like, the configuration of an automatic filling and packaging machine 1 provided with an electrode 20 for high-frequency dielectric heating according to the present embodiment will be described.

[0020] The automatic filling and packaging machine 1 is configured such that a first region P1 and a second region P2 of a laminated film P formed by stacking two vinylidene chloride-based resin films (hereinafter simply referred to as "films") F are arranged on the radially outer side and the radially inner side, respectively, and are overlapped. While sandwiching the first region P1 and the second region P2, high-frequency dielectric heating is performed to form a cylindrical film 100 in an envelope sticking format (see FIG. 3 and the like). The formed cylindrical film 100 is filled with the content C, and sealed and cut at predetermined lengths to obtain a packaged body 200 of a predetermined length. It is for automatically performing each process, and as shown in FIG. 1, it includes a film supply unit 10, an electrode 20 for high-frequency dielectric heating, a content supply unit 30, a sealing unit 40, and a cutting unit 50.

[0021] The film supply unit 10 includes a roller 11 configured to feed out the laminated film P by rotating at a predetermined rotational speed with the laminated film P wound thereon, a guide member group 12 that guides the laminated film P fed out by the roller 11 to a predetermined position, and a tubular body forming unit (not shown) that forms the laminated film P into a tubular body in an envelope pasting format by arranging and overlapping the first region P1 and the second region P2 of the laminated film P guided to the predetermined position on the radially outer side and the radially inner side, respectively. The rotational speed of the roller 11, the position of the guide member group 12, the configuration of the tubular body forming unit, etc. can be appropriately adjusted according to the type of the laminated film P, the required film supply speed, the position of the high-frequency dielectric heating electrode 20, etc.

[0022] The high-frequency dielectric heating electrode 20 is for forming the laminated film P continuously supplied at a predetermined speed (for example, 40 m / min) by the film supply unit 10 into a tubular film 100. As shown in FIG. 2, it has an external electrode 21 arranged further radially outside the first region P1 of the laminated film P formed into a tubular body by the tubular body forming unit of the film supply unit 10, and an internal electrode 22 arranged further radially inside the second region P2 of the laminated film P.

[0023] As shown in FIG. 2, a film 21A made of an electrical insulator is formed on the external electrode 21. Examples of the electrical insulator constituting the film 21A in the present embodiment include polyamide-based resins, polyimide-based resins, polyester-based resins, polyethylene-based resins, polypropylene-based resins, polystyrene-based resins, fluorine-based resins, polyurethane-based resins, acrylic-based resins, polyphenylene ether-based resins, polyacetal resins, phenol resins, epoxy resins, silicone resins, etc. as organic-based ones. Examples of inorganic electrical insulators include ceramics, mica, glass, etc. Inorganic electrical insulators are preferred from the viewpoints of heat resistance and abrasion resistance, and alumina, zirconia, and silicon carbide having high hardness among ceramics are more preferred. Note that materials such as silicone rubber that increase the frictional resistance are not preferred as the electrical insulator constituting the film 21A because the slipperiness with the film F deteriorates.

[0024] The thickness of the film 21A provided on the external electrode 21 is set to be 10 μm or more and 150 μm or less. The thickness of the film 21A is preferably 20 μm or more and 140 μm or less, more preferably 40 μm or more and 130 μm or less, and particularly preferably 40 μm or more and 90 μm or less. Thereby, the region A (see FIG. 2) where the temperature between the external electrode 21 and the internal electrode 22 becomes the highest can be shifted to the external electrode 21 side, and three out of the four films F can be more reliably welded from the outside to form the seal portion S (see FIGS. 3 to 5).

[0025] That is, by setting the thickness of the film 21A to be 10 μm or more, the region A where the temperature between the external electrode 21 and the internal electrode 22 becomes the highest can be sufficiently shifted to the external electrode 21 side. Therefore, it is possible to prevent a situation where the two films F constituting the first region P1 arranged on the outer side in the radial direction and the two films F constituting the second region P2 arranged on the inner side in the radial direction are welded and the sealability cannot be ensured. Further, by setting the thickness of the film 21A to be 150 μm or less, it is possible to prevent a situation where the output for welding becomes too large and a spark is generated due to minute fluctuations of the film F. In particular, it is preferable to set the thickness of the film 21A to be 40 μm or more and 90 μm or less.

[0026] The line roughness of the portion in contact with the film F of the external electrode 21 (i.e., the surface 21Aa of the coating 21A) is set to be not less than the maximum height Rz1 (μm) and not more than 100 (μm), and not less than the arithmetic mean roughness Ra 0.5 (μm) and not more than 10 (μm). Thereby, the frictional resistance between the external electrode 21 and the film F can be reduced. For example, continuous welding at a film speed of 30 to 40 m / min can be realized, and the slipperiness with respect to the film F can be appropriately exhibited. That is, by setting the line roughness of the said portion (the surface 21Aa of the coating 21A) to be not more than the maximum height Rz 100 (μm) and not less than the arithmetic mean roughness Ra 10 (μm), it is possible to prevent the occurrence of a situation in which the frictional resistance between the external electrode 21 and the film F increases and the film F pulsates. Further, by setting the line roughness of the said portion (the surface 21Aa of the coating 21A) to be not less than the maximum height Rz 1 (μm) and not less than the arithmetic mean roughness Ra 0.5 (μm), it is possible to prevent the occurrence of a situation in which the film becomes too smooth, the slipperiness with respect to the film F deteriorates, the frictional resistance increases, and the film F pulsates.

[0027] The content supply unit 30 is for supplying the content (for example, minced fish meat) C into the cylindrical film 100 formed by the high-frequency dielectric heating electrode 20. It has a cylindrical body 31 having a diameter slightly smaller than the diameter of the cylindrical film 100 and partially inserted into the cylindrical film 100, and a content supply source (not shown) for supplying the content C into the cylindrical film 100 via the cylindrical body 31.

[0028] The sealing unit 40 is for sealing the cylindrical film 100 filled with the content C every predetermined length (for example, 200 mm). The sealing unit 40 in the present embodiment employs a mechanism for binding and sealing the cylindrical film 100 every predetermined length using a pair of two aluminum wires 41. The pair of two aluminum wires 41 are attached to the cylindrical film 100 in a slightly separated state, and the cutter 51 of the cutting unit 50 described later is inserted into the gap formed between these aluminum wires 41.

[0029] The cutting unit 50 is for obtaining a packaging body 200 of a predetermined length by cutting a tubular film 100 of a predetermined length filled with and sealed with the content C inside. The cutting unit 50 in the present embodiment includes a cutter 51 configured to cut a portion of the tubular film 100 between a pair of two aluminum wires 41 of the sealing unit 40, and a drive mechanism (not shown) that drives the cutter 51.

[0030] Next, with reference to FIGS. 3 to 5, the configuration of the tubular film 100 formed by the automatic filling and packaging machine 1 including the high-frequency dielectric heating electrode 20 according to the present embodiment will be described.

[0031] As shown in FIG. 3, the tubular film 100 is a tubular film in an envelope pasting format having a seal portion S formed by sealing the first region P1 and the second region P2 of the laminated film P formed by laminating two films F in a state where the first region P1 and the second region P2 are arranged on the radially outer side and the radially inner side, respectively.

[0032] In the present embodiment, as shown in FIG. 3 and the like, as the first region P1 of the laminated film P, a region having a predetermined width slightly separated (by a width W1) from the outermost end of one edge P of the laminated film P is adopted, and as the second region P2 of the laminated film P, a region having a predetermined width slightly separated (by a width W2) from the outermost end of the other edge P of the laminated film P is adopted. That is, the first region P1 is a region near the edge that does not include one edge P of the laminated film P, and the second region P2 is a region near the edge that does not include the other edge P of the laminated film P. E1 , E2 , E1 , E2 E2 E2 E1 E1 E2 E2

[0033] The size and thickness of the film F are determined according to the size of the content C to be filled. The perimeter of the film F is usually in the range of 15 to 400 mm, often 30 to 300 mm, and widely adopted in the range of 40 to 200 mm. The length of the film F in the longitudinal direction is usually in the range of 50 to 400 mm, often 70 to 300 mm, and widely adopted in the range of 80 to 250 mm. Also, the thickness of the film F is determined considering the strength, barrier properties, etc. of the film according to the content C to be filled, but is usually in the range of 15 to 300 μm, often 18 to 200 μm, and widely adopted in the range of 20 to 150 μm. Among this range, setting the thickness to 15 to 25 μm is preferable because the film F has appropriate strength and is easy to cut.

[0034] As shown in FIGS. 3 and 5, the seal portion S is formed by welding two films F that constitute the first region P1 disposed on the outer side in the radial direction of the laminated film P 1A ,F 1B and one film F located on the outer side in the radial direction among the two films F that constitute the second region P2 disposed on the inner side in the radial direction of the laminated film P 2A ,F 2B . In the present embodiment, these three films F 2A are welded by performing high-frequency dielectric heating using the high-frequency dielectric heating electrode 20 described above. 1A ,F 1B ,F 2A

[0035] Note that, in the laminated film P, a region P E with a predetermined width W1 from the outermost end of the edge P A close to the first region P1 disposed on the outer side in the radial direction is a non-sealed portion (outer ear portion) N that can be pinched by the user. Through holes H are formed in the non-sealed portion N at predetermined intervals d in the longitudinal direction. The non-sealed portion N (region P A) is the area that serves as the starting point when cutting the seal part S and is easily torn by the user's hand. In this embodiment, an example of providing two rows of through holes H is shown, but only one row or three or more rows of through holes H may be provided.

[0036] Subsequently, a method for manufacturing the package 200 using the automatic filling and packaging machine 1 in this embodiment will be described.

[0037] First, while the laminated film P is being supplied at a predetermined speed to the high-frequency dielectric heating electrode 20 side by the film supply unit 10 of the automatic filling and packaging machine 1, the first region P1 and the second region P2 of the laminated film P are respectively arranged on the radially outer side and the radially inner side and overlapped to form a tubular body in the envelope pasting form (film supply step). Next, the first region P1 and the second region P2 overlapped in the film supply step are sandwiched between the external electrode 21 arranged on the radially outer side and the internal electrode 22 arranged on the radially inner side, and high-frequency dielectric heating is performed to seal, thereby forming a tubular film 100 having a seal part S (tubular film forming step).

[0038] In the tubular film forming step, since the external electrode 21 having a coating 21A with a predetermined thickness is arranged outside the first region P1 of the laminated film P, as shown in FIG. 2, the position of the region A (the darkest part in FIG. 2) that is most heated by high-frequency dielectric heating can be shifted to the radially outer side. Thereby, as shown in FIG. 3, the two films F 1A , F 1B constituting the first region P1 arranged on the radially outer side of the laminated film P, and the two films F 2A , F 2B constituting the second region P2 arranged on the radially inner side, and one film F 2A located on the radially outer side among them can be welded to form the seal part S.

[0039] Thereafter, the content supply unit 30 supplies and fills the inside of the tubular film 100 with a content (e.g., ground fish meat) C (content filling step), seals the tubular film 100 filled with the content C at predetermined lengths (e.g., 200 mm) by the sealing unit 40 (sealing step), and cuts the tubular film 100 of a predetermined length filled and sealed with the content C inside at the cutting unit 50 (cutting step). The package 200 obtained by the above process group will be commercialized through, for example, a retort treatment at about 120°C for 20 minutes.

[0040] When opening the package 200, the user first pinches the non-sealed part (outer ear part) N of the package 200 with a finger and applies a force to cut the seal part S by tearing along a direction (width direction) substantially orthogonal to the longitudinal direction of the package 200. When such a force is applied, the seal part S will be cut along the width direction. At this time, among the two films F 1A ,F 1B located on the outer side in the radial direction, the film F 1A will not peel off from the film F 1B located on the inner side in the radial direction, and the first region P1 can be separated from the second region P2 to surely release the sealed state. After that, the user can open the package 200 by cutting the laminated film P along the width direction of the package 200 or cutting the seal part S along the longitudinal direction of the package 200.

[0041] In the high-frequency dielectric heating electrode 20 according to the embodiment described above, in a state where the first region P1 and the second region P2 of the laminated film P formed by laminating two vinylidene chloride resin films F are arranged on the radially outer side and the radially inner side, respectively, and overlapped, an external electrode 21 arranged radially outside the first region P1 and an internal electrode 22 arranged radially inside the second region P2 sandwich the first region P1 and the second region P2 to perform high-frequency dielectric heating, and the first region P1 and the second region P2 are continuously welded, whereby a cylindrical film 100 in the form of a sealed envelope capable of filling and sealing various contents C (for example, ground meat, etc.) can be manufactured. At this time, since a film 21A made of an electrical insulator is formed on the external electrode 21, the region A where the temperature between the electrodes becomes the highest can be shifted to the external electrode 21 side. Therefore, two films F constituting the first region P1 arranged on the radially outer side and one film F located on the radially outer side among the two films F constituting the second region P2 arranged on the radially inner side can be welded to form a seal portion S. That is, since the seal portion S can be formed by welding three out of the four films F from the outside, when the seal portion S is cut to open the package 100, the film F located on the radially outer side among the two films F constituting the first region P1 arranged on the radially outer side can be prevented from peeling off from the film F located on the radially inner side. As a result, the possibility of opening failure can be reduced.

[0042] Also, in the high-frequency dielectric heating electrode 20 according to the embodiment described above, since the line roughness of the portion (the surface 21Aa of the film 21A) of the external electrode 21 that contacts the film F is set to be not less than the maximum height Rz1 (μm) and not more than 100 (μm) and not less than the arithmetic mean roughness Ra 0.5 (μm) and not more than 10 (μm), while moderately exhibiting the slipperiness with the film F, the frictional resistance between the external electrode 21 and the film F can be reduced, and for example, continuous welding at a film speed of 30 to 40 m / min can be realized.

[0043] In addition, in the high-frequency dielectric heating electrode 20 according to the embodiment described above, since the thickness of the coating film 21A is set to be 10 μm or more and 150 μm or less, it is possible to more surely weld three out of the four films from the outside and form the seal portion S.

[0044] Next, each example of the present invention will be described.

[0045] 〔Example 1〕 A vinylidene chloride-vinyl chloride copolymer (vinylidene chloride content / vinyl chloride content = 89% by mass / 11% by mass, weight average molecular weight 125,000) was melted and extruded from an annular die to produce an annular film. Inflation biaxial stretching was performed at a stretching temperature of 30°C, 3.0 times in the longitudinal direction, and 4.0 times in the width direction, and the inner sides of the annular films were overlapped to obtain a film stock having a thickness of 43 μm (the thickness of two films with a thickness of 21.5 μm). A strip-shaped laminated film was obtained by unwinding this and cutting it to a width of 86 mm.

[0046] The laminated film obtained by the above process was set in an automatic filling and packaging machine (manufactured by Asahi Kasei Corporation: trade name "ADP (registered trademark)") having the same configuration as that described in this embodiment, fed out, and the two side edges extending in the longitudinal direction were overlapped and wound into a cylindrical shape like an envelope sticker and run downstream. While running, the overlapped two side edges were sealed at high frequency using a high-frequency dielectric heating electrode to form a cylindrical film. In this example, a high-frequency dielectric heating electrode provided with an external electrode having a surface line roughness of maximum height Rz 40.0 μm and arithmetic mean roughness Ra 5.0 μm and a zirconia coating film with a thickness of 50 μm was employed.

[0047] 〔Example 2〕 A high-frequency dielectric heating electrode provided with an external electrode having a surface line roughness of maximum height Rz 80.0 μm and arithmetic mean roughness Ra 7.0 μm and a zirconia coating film with a thickness of 80 μm was employed, and a cylindrical film was formed in the same manner as in Example 1 for the rest.

[0048] 〔Example 3〕 An external electrode with a zirconia coating having a surface line roughness of maximum height Rz 4.0 μm and arithmetic mean roughness Ra 0.7 μm and a thickness of 20 μm was adopted, and a cylindrical film was formed in the same manner as in Example 1 for the rest.

[0049] [Example 4] An external electrode with a zirconia coating having a surface line roughness of maximum height Rz 41.5 μm and arithmetic mean roughness Ra 4.8 μm and a thickness of 118 μm was adopted, and a cylindrical film was formed in the same manner as in Example 1 for the rest.

[0050] [Example 5] An external electrode with a zirconia coating having a surface line roughness of maximum height Rz 39.2 μm and arithmetic mean roughness Ra 4.7 μm and a thickness of 23 μm was adopted, and a cylindrical film was formed in the same manner as in Example 1 for the rest.

[0051] [Example 6] An external electrode with an alumina coating having a surface line roughness of maximum height Rz 41.2 μm and arithmetic mean roughness Ra 4.4 μm and a thickness of 49 μm was adopted, and a cylindrical film was formed in the same manner as in Example 1 for the rest.

[0052] [Example 7] An external electrode with a zirconia coating having a surface line roughness of maximum height Rz 2.5 μm and arithmetic mean roughness Ra 0.3 μm and a thickness of 52 μm was adopted, and a cylindrical film was formed in the same manner as in Example 1 for the rest.

[0053] [Example 8] An external electrode with a zirconia coating having a surface line roughness of maximum height Rz 0.3 μm and arithmetic mean roughness Ra 0.2 μm and a thickness of 51 μm was adopted, and a cylindrical film was formed in the same manner as in Example 1 for the rest.

[0054] [Example 9] An external electrode with a polyester film having a surface line roughness of a maximum height Rz of 0.5 μm and an arithmetic mean roughness Ra of 0.4 μm and a thickness of 50 μm was adopted, and a tubular film was formed in the same manner as in Example 1 for the others.

[0055] 〔Example 10〕 An external electrode with a polyethylene film having a surface line roughness of a maximum height Rz of 0.5 μm and an arithmetic mean roughness Ra of 0.4 μm and a thickness of 60 μm was adopted, and a tubular film was formed in the same manner as in Example 1 for the others.

[0056] 〔Comparative Example 1〕 An external electrode with a zirconia film having a surface line roughness of a maximum height Rz of 120.0 μm and an arithmetic mean roughness Ra of 11.0 μm and a thickness of 50 μm was adopted, and a tubular film was formed in the same manner as in Example 1 for the others.

[0057] 〔Comparative Example 2〕 An external electrode with a zirconia film having a surface line roughness of a maximum height Rz of 40.0 μm and an arithmetic mean roughness Ra of 5.0 μm and a thickness of 170 μm was adopted, and a tubular film was formed in the same manner as in Example 1 for the others.

[0058] 〔Comparative Example 3〕 An external electrode with a zirconia film having a surface line roughness of a maximum height Rz of 0.5 μm and an arithmetic mean roughness Ra of 0.4 μm and a thickness of 5 μm was adopted, and a tubular film was formed in the same manner as in Example 1 for the others.

[0059] 〔Comparative Example 4〕 An external electrode with a zirconia film having a surface line roughness of a maximum height Rz of 39.5 μm and an arithmetic mean roughness Ra of 4.8 μm and a thickness of 8 μm was adopted, and a tubular film was formed in the same manner as in Example 1 for the others.

[0060] 〔Reference Example〕 An external electrode with a silicon rubber coating having a surface line roughness of maximum height Rz of 0.9 μm and arithmetic mean roughness Ra of 0.3 μm and a thickness of 10 μm was adopted, and a tubular film was formed in the same manner as in Example 1 for the others.

[0061] 〔Line roughness〕 In each of the above examples and comparative examples, a shape analysis laser microscope (manufactured by KEYENCE Corporation: trade name "LASER MICROSCOPE VK-X1000") was used to measure the maximum height Rz (μm) and arithmetic mean roughness Ra (μm) of the portion where the external electrode contacts the film, and this was taken as the line roughness. <Measurement preparation> Start the "Observation Application", place the side where the film of the external electrode contacts upwards, and install it on the rotary stage of the shape analysis laser microscope so that the vertical direction of the monitor represents the length direction of the external electrode. <Setting of measurement method> Set the magnification of the objective lens to 5 times, focus on the surface of the external electrode, and then switch the image from the camera image to the laser image on the operation panel. <Production of 3D image> Set the scan mode to "Laser Confocal" from "Basic Measurement" in the toolbar and adjust the brightness. Set the upper and lower limits of the external electrode surface to be measured and start the measurement. After the measurement was completed, the obtained 3D image was saved. Note that "Laser Confocal" is a scan method in which the light irradiated from the laser is reflected from the sample surface, and the focus position (height information) is detected from the intensity of the reflected light to measure the shape. <Measurement of line roughness> Start the "Multi-File Analysis Application", select "Line Roughness" from the toolbar, select a vertical line from the profile tool, set it to measure the area with a high height level in the 3D display image, and obtain the maximum height Rz (μm) and arithmetic mean roughness Ra (μm).

[0062] 〔Coating thickness〕 In each of the above examples and comparative examples, both the dimensions of the external electrode before coating with the electrical insulator and the dimensions of the external electrode after coating with the electrical insulator were measured with a micro gauge, and the coating thickness was measured. At this time, an electrical insulator was coated on one side of an external electrode having a substantially rectangular parallelepiped shape with a width of 40 mm, a length of 40 mm, and a thickness of 2 mm, and the dimension at a position 20 mm from the end of the coated side (i.e., a position near the approximate center of the side) was measured.

[0063] 〔Packaging suitability evaluation〕 In the cylindrical films obtained in the examples and comparative examples, minced fish meat was filled, and both ends were clipped with aluminum steel wires to produce 200 packages per minute having outer ear portions (unsealed portions) with a length of 200 mm and a width of 7 mm between the clips. The above filling operation was performed using 1500 m of a vinylidene chloride resin film, the number of times sparks occurred during the process was counted, and the packaging suitability was evaluated according to the following evaluation criteria. (Evaluation criteria) ○: The number of times sparks occurred during the manufacturing process was 0 times ×: The number of times sparks occurred during the manufacturing process was 1 time or more

[0064] 〔Retort resistance evaluation〕 1000 packages obtained during the above packaging suitability evaluation were subjected to a retort treatment at 120 °C for 20 minutes under the condition that the gauge pressure inside the heating can was 0.20 MPa using a high-temperature and high-pressure cooking sterilizer (manufactured by Nisshin Kikai Co., Ltd.: product name "RCS-40TGN") to obtain sealed packages. Among the sealed packages after the retort treatment, the number of packages with broken bags was counted, and the retort resistance was evaluated according to the following evaluation criteria. (Evaluation criteria) ○: The number of broken bags was 0 ×: The number of broken bags was 1 or more

[0065] 〔Easy-openability evaluation〕 Among the sealed packages after the retort treatment, 100 packages without bag breakage were randomly sampled. For the obtained samples, the outer ear part (non-sealing part) was pinched and manually opened to evaluate by sensory inspection how much force was required for opening. Specifically, 10 panelists each opened 10 sealed package samples, and evaluated each sealed package with a sensory inspection score of 0 to 2 points (2 points: anyone can easily open it; 1 point: anyone can open it with force; 0 point: cannot be opened by bare hands). The average value of the sensory inspection scores of a total of 100 packages was rounded to the second decimal place as the evaluation score, and based on the obtained evaluation score, the easy-openability was evaluated according to the following criteria. (Evaluation Criteria) ◎: The average value of the sensory inspection scores is 2.0 ○: The average value of the sensory inspection scores is 1.5 or more and less than 2 △: The average value of the sensory inspection scores is 1 or more and less than 1.5 ×: The average value of the sensory inspection scores is less than 1

[0066] 〔Abrasion Resistance Evaluation〕 Similar to the packaging suitability evaluation, after using 2 rolls of 1500 m of vinylidene chloride resin film, the abrasion resistance of the electrode was evaluated visually according to the following criteria. (Evaluation Criteria) 〇: No abnormality in the coating state of the electrode ×: Holes or abrasions are found in the coating of the electrode

[0067] The results of each performance evaluation are shown in Table 1 (Examples) and Table 2 (Comparative Examples) below.

Table 1

Table 2

[0068] As is clear from Table 1, in each of Examples 1 to 7 where the line roughness of the surface of the coating of the external electrode is 1 μm or more and 100 μm or less in maximum height Rz and 0.5 μm or more and 10 μm or less in arithmetic mean roughness Ra, and the thickness of the coating of the external electrode is 10 μm or more and 150 μm or less, evaluations of "Δ" or higher were obtained for all performances. Also, in each of Examples 8 to 10 where the line roughness of the surface of the coating of the external electrode is less than 1 μm in maximum height Rz and less than 0.5 μm in arithmetic mean roughness Ra, evaluations of "Δ" or higher were obtained for all performances. In all of Examples 1 to 10, the line roughness of the surface of the coating of the external electrode is 100 μm or less in maximum height Rz and 10 μm or less in arithmetic mean roughness Ra, and the thickness of the coating of the external electrode is 10 μm or more and 150 μm or less. On the other hand, in Comparative Example 1 where the line roughness of the surface of the coating exceeds 100 μm in maximum height Rz and exceeds 10 μm in arithmetic mean roughness Ra, the packaging suitability and retort resistance were evaluated as "×", and in Comparative Example 2 where the thickness of the coating exceeds 150 μm, the packaging suitability, retort suitability, and easy-openability were evaluated as "×". In Comparative Example 3 where the line roughness of the surface of the coating is less than 1 μm in maximum height Rz and less than 0.5 μm in arithmetic mean roughness Ra, the easy-openability was evaluated as "×", and in Comparative Example 4 where the thickness of the coating is less than 10 μm, the easy-openability was also evaluated as "×". In the reference example where the coating material is silicone rubber and the line roughness of the surface of the coating is less than 1 μm in maximum height Rz and less than 0.5 μm in arithmetic mean roughness Ra, it was evaluated as "not suitable for packaging" in the packaging suitability evaluation.

[0069] The present invention is not limited to the above embodiments, and those in which a person skilled in the art makes appropriate design changes to such embodiments are also included in the scope of the present invention as long as they have the features of the present invention. That is, each element included in the above embodiments and its arrangement, material, conditions, shape, size, etc. are not limited to those exemplified and can be changed as appropriate. Also, each element included in the above embodiments can be combined as long as it is technically possible, and those obtained by combining these are also included in the scope of the present invention as long as they include the features of the present invention.

Explanation of Reference Signs

[0070] 20…Electrode for high-frequency dielectric heating 21…External electrode 21A…Coating 21Aa…Surface of the coating (portion in contact with the film) 22…Internal electrode 100…Cylindrical film S…Sealing part F…Film made of vinylidene chloride resin P…Laminated film P1…First region P2…Second region

Claims

1. A high-frequency dielectric heating electrode for forming a tubular film in an envelope pasting form by performing high-frequency dielectric heating across a first region and a second region of a laminated film formed by stacking two vinylidene chloride resin films, with the first region and the second region arranged on the outer and inner sides in the radial direction, respectively, in a stacked state, comprising: an external electrode disposed radially outside the first region; an internal electrode disposed radially inside the second region, wherein a film made of an electrical insulator is formed on the external electrode, while the film is not formed on the internal electrode, the line roughness of the portion of the external electrode in contact with the vinylidene chloride resin film is set to a maximum height Rz100 (μm) or less and an arithmetic mean roughness Ra10 (μm) or less, and the thickness of the film is set to 10 μm or more and 150 μm or less.

2. The high-frequency dielectric heating electrode according to claim 1, wherein the line roughness of the portion of the external electrode in contact with the vinylidene chloride resin film is set to a maximum height Rz1 (μm) or more and an arithmetic mean roughness Ra0.5 (μm) or more.

3. The high-frequency dielectric heating electrode according to claim 1 or 2, wherein the thickness of the film is set to 40 μm or more and 130 μm or less.

4. The high-frequency dielectric heating electrode according to claim 3, wherein the thickness of the film is set to 40 μm or more and 90 μm or less.

5. The high-frequency dielectric heating electrode according to any one of claims 1 to 4, wherein the electrical insulator is one or more inorganic electrical insulators selected from ceramics, mica, and glass.

6. The high-frequency dielectric heating electrode according to any one of claims 1 to 4, wherein the electrical insulator is one or more inorganic electrical insulators selected from alumina, zirconia, and silicon carbide among ceramics.

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