Packaging bag, metal powder-resin plate package using said packaging bag, and method for manufacturing metal powder-resin plate

Abstract

A packaging bag that can be used to produce metal powder-resin plates of a predetermined shape and thickness, and a metal powder-resin plate package using the same are provided. [Solution] A packaging bag 1 for producing a metal powder-resin plate by placing a mixture of metal powder and thermosetting resin inside the bag and thermosetting it, the packaging bag 1 having opposing front and back films, an opening 5, and an outer edge seal portion 4 extending along the outer edge of the packaging bag 1, the seal strength of the outer edge seal portion 4 being 2N / 15mm width or more and 15N / 15mm width or less, the sealant layer constituting the innermost layer of the packaging bag 1 being a thermoplastic resin, and the peel strength with the thermosetting resin being 1N / 15mm width or less according to the test method described below. <Test Method> The sealant layer of the packaging bag and the thermosetting resin are bonded by heating at 120°C for 10 minutes, and the load when peeled off using the 180°C peeling method (pulling speed 50mm / min) in a 25°C atmosphere is measured.

Description

[Technical Field]

[0001] The present invention relates to a packaging bag, a metal powder-resin plate package using the packaging bag, and a method for producing a metal powder-resin plate. [Background technology]

[0002] Compounds containing metal powder and resin are used as raw materials for a variety of industrial products depending on the physical properties of the metal powder, such as inductors, sealing materials, electromagnetic wave shields (EMI shields), magnetic materials, magnetic cooling magnetic materials, and bonded magnets (Patent Document 1).

[0003] The compound containing the metal powder and resin is processed into a predetermined shape and thickness as needed. For example, it may be processed into a plate-shaped or sheet-shaped metal powder-resin plate, in which case a thermosetting epoxy resin or the like is generally used as the binder resin (Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-40258 [Patent Document 2] Patent Publication No. 2021-106215 [Patent Document 3] WO2023 / 228822 Summary of the Invention [Problem to be solved by the invention]

[0005] When manufacturing the above-mentioned metal powder-resin plate, the binder resin itself has adhesive properties with a mold. Therefore, if the metal powder-resin plate is press-molded or heat-cured using a mold, the binder resin in the metal powder-resin plate will adhere to the mold, etc., making it impossible to manufacture the metal powder-resin plate.

[0006] For this reason, methods have been adopted in which a release sheet is used as in Patent Document 2 (see FIG. 5) or wax is added to the resin composition as in Patent Document 1. However, it is time-consuming to sandwich release sheets above and below each press-molding of the metal powder-resin plate, and further, when wax is added to the resin composition, the wax may lead to a deterioration in the physical properties of the metal powder-resin plate depending on the application, limiting its use. [Means for solving the problem]

[0007] As a result of extensive research to solve the above problems, the present inventors discovered that by using a packaging bag having a sealant film (sealant layer) with a predetermined seal strength and peeling properties when producing metal powder-resin plates, it is possible to produce a packaging bag that can produce metal powder-resin plates of a predetermined shape and thickness, and a metal powder-resin plate package using the same, and thus completed the present invention. Specifically, the present invention provides the following.

[0008] (1) A packaging bag for producing a metal powder-resin plate, which is made by placing a mixture of metal powder and thermosetting resin inside the bag and thermosetting the mixture, The packaging bag has a front film and a back film facing each other, an opening, and an outer edge seal portion extending along the outer edge of the packaging bag, The seal strength of the outer edge seal portion is 2N / 15mm width or more and 15N / 15mm width or less, The packaging bag has a sealant layer that forms the innermost layer of the packaging bag and is made of a thermoplastic resin, and the peel strength with respect to the thermosetting resin measured by the following test method is 1 N / 15 mm width or less. <Test Method> The sealant layer of the packaging bag is bonded to the thermosetting resin by heating at 120°C for 10 minutes, and the load when peeled off using a 180°C peeling method (pulling speed 50 mm / min) in a 25°C atmosphere is measured.

[0009] (2) The packaging bag according to (1), wherein the sealant layer contains more than 50% by mass of a propylene-based polymer and less than 50% by mass of an ethylene-based polymer.

[0010] (3) The packaging bag according to (1), wherein the front surface film and the back surface film are laminated films each having a base material layer and the sealant layer.

[0011] (4) The packaging bag according to (1), wherein the thermosetting resin is an epoxy resin.

[0012] (5) A metal powder-resin plate package in which a metal powder-resin plate is contained in the packaging bag described in any one of (1) to (4), the metal powder-resin plate being formed by placing a mixture of metal powder and a thermosetting resin inside the bag and thermosetting the mixture.

[0013] (6) a first step of placing a mixture of metal powder and thermosetting resin inside a packaging bag; a second step of adjusting the mixture to a predetermined thickness; and a third step of heat-curing the packaging bag containing the mixture to produce a metal powder-resin plate package. The packaging bag has a front film and a back film facing each other, an opening, and an outer edge seal portion extending along the outer edge of the packaging bag, The seal strength of the outer edge seal portion is 2N / 15mm width or more and 15N / 15mm width or less, A method for manufacturing a metal powder-resin plate, wherein the sealant layer constituting the innermost layer of the packaging bag is made of a thermoplastic resin, and the peel strength with the thermosetting resin measured by the following test method is 1 N / 15 mm width or less. <Test Method> The sealant layer of the packaging bag is bonded to the thermosetting resin by heating at 120°C for 10 minutes, and the load when peeled off using a 180°C peeling method (pulling speed 50 mm / min) in a 25°C atmosphere is measured.

[0014] (7) The method for producing a metal powder-resin plate according to claim 6, further comprising a fourth step of peeling the front surface film and the back surface film from the outer edge seal portion after the third step. [Effects of the Invention]

[0015] According to the packaging bag of the present invention, the metal powder-resin plate package using the packaging bag, and the method for producing a metal powder-resin plate, it is possible to produce a metal powder-resin plate of a predetermined shape and thickness. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a plan view showing an example of a packaging bag. [Figure 2] FIG. 2 is a diagram showing the layer structure of a packaging film used in a packaging bag. [Figure 3] FIG. 1 is a process diagram showing an example of a method for manufacturing a metal powder-resin plate. [Figure 4] FIG. 1 is a process diagram showing an example of a method for manufacturing a metal powder-resin plate. [Figure 5] FIG. 1 is a process diagram showing an example of a conventional method for manufacturing a metal powder-resin plate. DETAILED DESCRIPTION OF THE INVENTION

[0017] Specific embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be practiced with appropriate modifications within the scope of the object of the present invention. Furthermore, in this specification, the expression "X to Y" (X and Y are arbitrary numerical values) means "at least X and at most Y."

[0018] <<Summary of the Invention>> The packaging bag of the present invention is a packaging bag for producing a metal powder-resin plate by placing a mixture of metal powder and thermosetting resin inside the bag and thermosetting it, and the packaging bag has opposing surface and back films, an opening, and an outer edge seal portion extending along the outer edge of the packaging bag.

[0019] The packaging bag of the present invention is characterized in that the seal strength of the outer edge seal portion is 2 N / 15 mm width or more and 15 N / 15 mm width or less, the sealant layer constituting the innermost layer of the packaging bag is a thermoplastic resin, and the peel strength with a thermosetting resin such as an epoxy resin is 1 N / 15 mm width or less, as measured by the test method described below.

[0020] The test method involves heating the sealant layer of the packaging bag to a thermosetting resin such as epoxy resin at 120°C for 10 minutes to bond them together, and then measuring the load when peeled off using a 180°C peeling method (tensile speed 50mm / min) in a 25°C atmosphere.

[0021] By manufacturing metal powder-resin plates using a packaging bag that can form an outer edge seal portion with such a predetermined seal strength and has a sealant layer with predetermined peel properties as the innermost layer, it is possible to effectively prevent the binder resin in the metal powder-resin plate from adhering to a mold, etc. during press molding or heat curing, and to efficiently manufacture metal powder-resin plates of the predetermined shape and thickness.

[0022] Furthermore, by packaging the mixture of metal powder and thermosetting resin in a packaging bag, the mixture can be transported and stored in its pre-hardened state, improving the handling of the mixture and preventing foreign matter from being mixed into the packaging bag or corrosion during transportation. Furthermore, adjusting the size of the packaging bag inevitably determines the amount of mixture to be filled in the bag, so the width of the metal powder-resin plate can be determined without using a mold. Furthermore, the amount of mixture to be added can be estimated from the size of the packaging bag, reducing the amount of remaining mixture.

[0023] The packaging bag of the present invention will be described below along with specific embodiments. Note that the packaging bag of the following embodiment is one embodiment of the present invention, and the present invention is not limited to the following embodiment.

[0024] <Packaging bag> FIG. 1 is a diagram showing an example of a packaging bag 1 according to the present embodiment. The packaging bag 1 is used to produce a metal powder-resin plate by storing a mixture of metal powder and thermosetting resin inside the bag and then subjecting the mixture to molding and thermosetting processes. The packaging bag 1 is a so-called flat pouch-type three-sided sealed packaging bag that includes a surface film 2 that forms the surface and a back film 3 that forms the back.

[0025] The inner surfaces of the front film 2 and the back film 3 are joined together by a seal portion. As shown in FIG. 1, the seal portion has an outer edge seal portion 4 that extends along the outer edge of the packaging bag 1. The outer edge seal portion 4 includes a bottom seal portion 4a that extends along the bottom edge and a pair of side seal portions 4b that extend along a pair of side portions. As shown in FIG. 1, in the state before the contents are filled (stored) in the packaging bag 1 (a state in which no contents are filled (stored)), the top of the packaging bag 1 has an opening 5. A mixture of metal powder and thermosetting resin can be filled and stored inside the packaging bag 1 through this opening 5. After the mixture is filled and stored, the opening 5 of the packaging bag 1 is heat-sealed as necessary.

[0026] Here, the terms "surface film" and "back surface film" mentioned above are merely used to divide each film according to its positional relationship, and the terms do not limit the method of providing the packaging film 10 when manufacturing the packaging bag 1. For example, the packaging bag 1 may be manufactured using one packaging film 10 in which the surface film 2 and the back surface film 3 are continuously disposed, or may be manufactured using a total of two packaging films 10, one surface film 2 and one back surface film 3.

[0027] The packaging bag 1 is made by preparing two packaging films 10 and overlapping them so that the sealant layer 13 (described later) of the front packaging film 10 faces the sealant layer 13 of the back packaging film 10. In addition to the three-sided seal described above, a two-sided sealed package may be formed by folding back the bottom of a single packaging film having a front film 2 and a back film 3 connected together, and then forming side seals only. Furthermore, the packaging may be a pillow packaging bag or a gusset packaging bag.

[0028] Heat sealing can be performed by any known method, such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, or ultrasonic sealing.

[0029] Next, an example of the layer structure of the packaging film 10 that constitutes the packaging bag 1 according to this embodiment will be described.

[0030] [Layer structure of packaging film 10 (surface film 2, back film 3)] As shown in Fig. 2, the packaging film 10 is a laminate (laminate film) in which a base layer 11, an adhesive layer 12, and a sealant layer 13 are laminated in this order. Since the packaging bag 1 described above undergoes a heat curing process for the mixture of metal powder and a thermosetting resin contained inside the bag, it is preferable that the packaging film 10 has heat resistance above a predetermined temperature.

[0031] The packaging film 10 is not limited to the laminated film described above, but may be a single-layer film composed solely of the sealant layer 13. When the packaging film 10 is a laminated film including the base layer 11, it is possible to impart rigidity and dimensional stability to the packaging bag 1, and to minimize the occurrence of wrinkles during the heat curing process. Furthermore, when the packaging film 10 is a single-layer film 13 composed solely of the sealant layer, the layer structure of the packaging film 10 can be reduced, thereby reducing the cost of the packaging bag 1.

[0032] [Base material layer 11] The base material layer 11 is a base material that forms the base of the packaging film 10, and is made of a heat-resistant material to withstand the heat treatment that occurs in the manufacturing process of the metal powder-resin plate, which will be described later. The provision of the base material layer 11 not only makes it possible to impart rigidity and dimensional stability to the packaging bag 1, but also to minimize the occurrence of wrinkles and the like during the curing process.

[0033] The material of the base layer 11 is not particularly limited, but is preferably a material that can withstand a predetermined temperature or higher. Specifically, a material that can withstand a heat of 100°C or higher is preferred, and a material that can withstand a heat of 130°C or higher is more preferred. Note that a material that can withstand a heat of 100°C or higher means, for example, a material whose softening point, melting point, glass transition point, etc. is 100°C or higher.

[0034] Examples of materials that can be used for the base layer 11 include crystalline or amorphous resin materials such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, polybutylene naphthalate, polypropylene, polycarbonate, polyamide, polyamideimide, polyimide, polyetheretherketone, polytetrafluoroethylene, and polyethersulfone. These materials may be unstretched, uniaxially or biaxially stretched, or may be a mixed resin (alloy) of two or more types.

[0035] The base layer 11 may also contain additives other than the resin material, such as lubricants, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing fibers, reinforcing agents, antistatic agents, flame retardants, flame resistant agents, foaming agents, and mildew inhibitors.

[0036] The thickness of the base layer 11 is not particularly limited, but is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, and even more preferably 6 μm or more and 25 μm or less. When the thickness of the base layer 11 is 1 μm or more, dimensional stability can be more effectively imparted and the occurrence of wrinkles during the curing process can be more effectively suppressed. When the thickness of the base layer 11 is 100 μm or less, the cost of the packaging bag 1 can be more effectively reduced.

[0037] Furthermore, the base material layer 11 may be configured with a plurality of layers. When the base material layer 11 is configured with a plurality of layers, the base material layers can be bonded to each other via an adhesive layer, which will be described later.

[0038] [Adhesive layer 12] The packaging film 10 may include an adhesive layer 12. The base material layer 11 is bonded to the sealant layer 13 via the adhesive layer 12. One example of the adhesive layer 12 is a layer (adhesive layer) formed from an adhesive containing a base resin, a curing agent, and optionally a solvent, and further containing various other additives as necessary. The adhesive is preferably a two-component type in which the base resin and the curing agent are mixed immediately before use. When forming the adhesive layer, the base resin reacts with the curing agent to crosslink and become highly molecular weight.

[0039] When a two-component adhesive consisting of a base agent and a curing agent is used, the adhesive is applied to the surface of the substrate layer 11 to be joined, and then the solvent component from the applied adhesive evaporates, forming an adhesive layer 12 on the surface of the substrate layer 11. This adhesive film hardens while bonded to the surface of the substrate to be joined, becoming the adhesive layer 12. There are no particular limitations on the method for applying the adhesive to the surface of the substrate, but examples include a gravure coater method, a roll coater method, and a brush coating method.

[0040] The adhesive forming the adhesive layer 12 is not limited to the adhesive used in the dry lamination method, but may also be an anchor coating agent used in the melt extrusion method.

[0041] The thickness of adhesive layer 12 is not particularly limited, but is preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 1 μm to 6 μm. When the thickness of adhesive layer 12 is 0.1 μm or more, the substrate layer 11 and the sealant layer 13 can be more firmly bonded. When the thickness of adhesive layer 12 is 10 μm or less, the cost of packaging bag 1 can be more effectively reduced.

[0042] [Sealant layer] The packaging film 10 includes a sealant layer 13. The sealant layer 13 is made of a thermoplastic resin, and the seal strength of the outer edge seal formed by joining the sealant layers together is 2 N / 15 mm width or more and 15 N / 15 mm width or less, and the peel strength with the thermosetting resin is 1 N / 15 mm width or less.

[0043] The peel strength test method involves heating the sealant layer of the packaging bag to a thermosetting resin such as epoxy resin for 10 minutes at 120°C to bond them together, and then measuring the load when peeling them off using a 180°C peeling method (tensile speed 50 mm / min) in an atmosphere of 25°C. Peel strength is measured according to JIS K7127:1999.

[0044] By selecting the material of the sealant layer so that the seal strength of the outer edge seal formed by joining such sealant layers together and the peel strength between the sealant layer and the epoxy resin are within a specified range, adhesion of the binder resin in the metal powder-resin plate can be effectively suppressed during press molding and thermal curing, while allowing for easy peeling from the metal powder-resin plate, allowing for efficient production of metal powder-resin plates of the specified shape and thickness.

[0045] If the seal strength of the outer edge seal 4 is less than 2 N / 15 mm width, the seal strength of the edge seal will be weak and the bag will no longer function as a packaging bag. If the seal strength of the edge seal exceeds 15 N / 15 mm width, it will be difficult to peel the front and back films from the outer edge seal in the fourth step described below. It will also be difficult to peel the thermosetting resin, making it difficult to produce a metal powder-resin plate of the specified shape and thickness.

[0046] The seal strength of the outer edge seal portion 4 is preferably 2.5 N / 15 mm width or more and 14.5 N / 15 mm width or less, more preferably 3 N / 15 mm width or more and 10 N / 15 mm width or less, and even more preferably 5 N / 15 mm width or more and 8 N / 15 mm width or less. The seal strength is measured according to JIS Z0238:1988.

[0047] On the other hand, the peel strength of the sealant layer 13 with respect to the thermosetting resin is preferably 0.7 N / 15 mm or less, more preferably 0.4 N / 15 mm or less, and even more preferably 0.1 N / 15 mm or less, which facilitates peeling of the front and back films from the metal powder-resin plate in the fourth step described below.

[0048] An example of a material that can realize such a sealant layer 13 is one containing two incompatible polyolefin resins. Examples of the two incompatible polyolefin resins include one containing a polyethylene resin and a polypropylene resin, and preferably one containing more than 50% by mass of a propylene polymer and less than 50% by mass of an ethylene polymer.

[0049] In this specification, the term "polyethylene resin" and the like are used to refer not only to "polyethylene resin" but also to a copolymer containing, for example, 50% or more of a polyethylene main chain and in which a part of the main chain is replaced with another main chain different from polyethylene.

[0050] Furthermore, by containing two incompatible polyolefin resins in this way, the layer functions as an easy-peel layer that exhibits peelability by cohesive failure.

[0051] Examples of polyethylene resins include low-density polyethylene, linear low-density polyethylene, metallocene-catalyzed linear low-density polyethylene, and ethylene-methacrylic acid copolymer (EMAA). The polyethylene resin may also be a random copolymer of ethylene and a small amount of an α-olefin having 3 to 10 carbon atoms, such as propylene, 1-butene, 1-heptene, 1-hexene, 1-octene, or 4-methyl-1-pentene.

[0052] The melt flow rate (MFR) (ASTM D1238, 190°C, 2160g load) of the polyethylene resin is not particularly limited, but is preferably 0.01 to 100g / 10 min, and more preferably 0.1 to 70g / 10 min. The lower limit of the melt flow rate (MFR) (ASTM D1238, 190°C, 2160g load) of the polyethylene resin is preferably 0.01g / 10 min or more, and more preferably 0.1g / 10 min or more. The upper limit of the melt flow rate (MFR) (ASTM D1238, 190°C, 2160g load) of the polyethylene resin is preferably 100g / 10 min or less, and more preferably 70g / 10 min or less.

[0053] Examples of polypropylene resins include homopolypropylene, propylene-ethylene random copolymers (polypropylene random copolymers), and propylene-ethylene block copolymers (polypropylene block copolymers).

[0054] The melt flow rate (MFR) (ASTM D1238, 190°C, 2160g load) of the polypropylene resin is not particularly limited, but is preferably 0.5 to 50g / 10 min, and more preferably 3 to 20g / 10 min. The lower limit of the melt flow rate (MFR) (ASTM D1238, 190°C, 2160g load) of the polypropylene resin is preferably 0.5g / 10 min or more, and more preferably 3g / 10 min or more. The upper limit of the melt flow rate (MFR) (ASTM D1238, 190°C, 2160g load) of the polypropylene resin is preferably 50g / 10 min or less, and more preferably 20g / 10 min or less.

[0055] Among these, it is particularly preferable that the sealant layer 13 contains low-density polyethylene (LDPE) and a propylene-ethylene random copolymer as the two incompatible polyolefin resins.

[0056] When the sealant layer 13 contains a polyethylene resin and a polypropylene resin, the ratio of the polyethylene resin content (parts by mass) in the sealant layer to the polypropylene resin content (parts by mass) in the sealant layer is preferably 60:40 to 90:10, and more preferably, for example, 70:30 to 80:20. By containing the polyethylene resin and the polypropylene resin in this range, it becomes possible to maintain the seal strength of the outer edge seal portion while effectively preventing the binder resin in the metal powder-resin plate from adhering to a mold or the like during press molding or heat curing.

[0057] The sealant layer 13 may be a single layer or may be a multilayer. The sealant layer 13 may be laminated on the base layer 11 using a melt extrusion method, or the sealant layer 13 made of a pre-formed plastic film may be bonded to the base layer 11 using a dry lamination method. The sealant layer 13 is preferably unstretched.

[0058] The thickness of the sealant layer 13 is not particularly limited, but is preferably 20 μm or more and 100 μm or less, more preferably 30 μm or more and 80 μm or less, and even more preferably 35 μm or more and 75 μm or less. The lower limit of the thickness of the sealant layer 13 is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 35 μm or more. The upper limit of the thickness of the sealant layer 13 is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 75 μm or less. By making the thickness of the sealant layer 13 20 μm or more, the seal strength of the edge seal portion can be kept within a preferred range. By making the thickness of the sealant layer 13 100 μm or less, the cost of the packaging bag 1 can be more effectively reduced.

[0059] As a sealant film containing the above-mentioned polyethylene-based resin and polypropylene-based resin and containing more than 50 mass% of a propylene-based polymer and less than 50 mass% of an ethylene-based polymer, commercially available products such as product name: CMPS 013C (manufactured by RM Tohcello Co., Ltd.) and product name: TAF680C (manufactured by RM Tohcello Co., Ltd.) can also be used.

[0060] <Package containing a mixture> The package according to this embodiment is a package (filled with contents) in which a mixture of metal powder and thermosetting resin is contained within the above-described packaging bag. As described above, by providing a sealant layer having a predetermined seal strength and peeling properties as the innermost layer, it is possible to effectively prevent the binder resin in the metal powder-resin plate from adhering to a mold or the like during press molding or thermosetting, and to efficiently manufacture a metal powder-resin plate of a predetermined shape and thickness.

[0061] Furthermore, by storing the mixture of metal powder and thermosetting resin in a packaging bag, it is possible to transport and store the mixture in its pre-hardened state, which improves the handling properties of the mixture and prevents foreign matter from getting into the packaging bag or causing corrosion during transportation.

[0062] <Metal powder-resin plate manufacturing method> Next, a method for manufacturing a metal powder-resin plate using the packaging bag and package according to this embodiment will be described. The metal powder-resin plate 100 is manufactured by placing a mixture P of metal powder and thermosetting resin in the above-mentioned packaging bag 1, shaping it into a predetermined shape, and then performing a heat curing process.

[0063] The mixture P (a mixture of metal powder and thermosetting resin) contained inside the packaging bag will be described below using the magnetic refrigeration composite material, which is an application of Patent Document 3, as an example.

[0064] [Mixture P (mixture of metal powder and thermosetting resin)] The mixture P contains at least a metal powder and a thermosetting resin. The metal powder contained in the mixture P is not particularly limited and is appropriately determined depending on the intended use of the metal powder-resin plate to be manufactured. For example, the metal powder may contain at least one selected from the group consisting of iron (Fe), copper (Cu), titanium (Ti), lanthanum (La), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), praseodymium (Pr), neodymium (Nd), samarium (Sm), and dysprosium (Dy). The metal powder may be a metal powder consisting of one of these metals alone, a metal compound containing one of these metals (e.g., a metal oxide or metal sulfide), or a metal alloy. In addition to these metals, the powder may contain elements other than metal elements, such as oxygen (O), beryllium (Be), phosphorus (P), boron (B), or silicon (Si).The powder may also contain two or more types of metal powder.

[0065] Depending on the intended use of the metal powder-resin plate to be manufactured, the metal powder may be soft magnetic or ferromagnetic.Specific examples include La(Fe,Si)-based materials, Laves phases such as cubic MgCu2-type, hexagonal MgZn2-type, and hexagonal MgNi2-type, Ga(Si,Ge)-based materials such as solid solutions of Gd5Ge4 and Gd5Si4, manganese-based perovskite oxides such as LaMnO3 and CaMnO3, Heusler alloys, which are intermetallic compounds expressed by the general formula X2YZ, and MnAs-based materials.

[0066] The shape of the metal powder is not particularly limited and is determined appropriately depending on the intended use of the metal powder-resin plate to be manufactured. For example, the metal powder may be approximately spherical. When the metal powder is approximately spherical, its surface becomes smooth, which tends to reduce the frictional force acting between the metal powder particles and improve the flowability.

[0067] The thermosetting resin functions as a binder for the metal powder and provides mechanical strength to the metal powder-resin plate produced from the mixture P. Examples of the thermosetting resin include at least one selected from the group consisting of epoxy resins, phenolic resins, and polyamideimide resins. Among these, those containing epoxy resins are particularly preferred. In this specification, the term "thermosetting resin" refers to a curable resin before curing (uncured).

[0068] The thermosetting resin may contain a curing agent as needed. When the thermosetting resin contains an epoxy resin, it is preferable to contain a curing agent having an active group (phenolic OH group) that reacts with an epoxy group.

[0069] The content of metal powder contained in mixture P depends on the intended use of the metal powder-resin plate to be manufactured, but is preferably 50% by mass or more and 98% by mass or less, more preferably 60% by mass or more and 95% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less, based on the total amount of mixture P. The lower limit of the content of metal powder contained in mixture P is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on the total amount of mixture P. The lower limit of the content of metal powder contained in mixture P is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, based on the total amount of mixture P.

[0070] The content of the thermosetting resin contained in the mixture P depends on the intended use of the metal powder-resin plate to be manufactured, but is preferably 2% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less, based on the total amount of the mixture P. The lower limit of the content of the thermosetting resin contained in the mixture P is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of the mixture P. The upper limit of the content of the thermosetting resin contained in the mixture P is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on the total amount of the mixture P.

[0071] The mixture P may contain other components as needed. For example, it may contain an organic solvent or additives. Examples of additives include coupling agents (e.g., silane coupling agents) that improve adhesion between the resin and the metal powder, dispersants, curing accelerators, lubricants, thermoplastic resins, antioxidants, UV absorbers, light stabilizers, fillers, lubricants, reinforcing fibers, reinforcing agents, antistatic agents, flame retardants, flame resistant agents, foaming agents, antifoaming agents, and antifungal agents.

[0072] Next, a more specific method for producing a metal powder-resin plate will be described. Note that, although specific production conditions such as heating conditions and time are described below, the method for producing a metal powder-resin plate of the present invention is not limited to the following conditions, and can be appropriately modified depending on the intended use of the metal powder-resin plate, the components contained in the mixture P, the shape of the packaging bag, and the layer structure of the packaging film that makes up the packaging bag.

[0073] [Applicator method] Fig. 3 is a process diagram of the applicator method, which is an example of a method for manufacturing a metal powder-resin plate. Fig. 3(a) to (f) are diagrams explaining the process for manufacturing a metal powder-resin plate 100 from a mixture P of metal powder and a thermosetting resin.

[0074] First, in the first step, a mixture P of metal powder and thermosetting resin is placed on the lower (bottom) side of a packaging bag 1, as shown in FIG. 3(a).

[0075] Next, in the second step, as shown in Figures 3(b) and 3(c), the mixture 1 contained in the packaging bag 1 is spread to a predetermined thickness within the packaging bag 1 using an applicator T. Here, since the mixture 1 is contained on the lower (bottom) side of the packaging bag 1, the applicator T moves from the lower (bottom) side of the packaging bag 1 toward the opening 5, thereby spreading the mixture P to a predetermined thickness within the packaging bag 1 toward the opening 5. Note that the applicator T can be, for example, a roughly U-shaped member having a recessed portion with a dimension corresponding to the total thickness of the metal powder-resin plate 100 and the thickness of the packaging bag 1, but is not limited to this as long as it is a tool that can make the thickness uniform.

[0076] Subsequently, in the third step, the mixture P that has been pressed and spread inside the packaging bag 1 is heated together with the packaging bag 1 at a temperature of, for example, 120°C for 10 minutes to harden the mixture P. Here, for example, an oven or the like can be used for the heat hardening treatment. Note that the second step and the third step can also be performed simultaneously. As a result, as shown in Figure 3(d), the mixture P hardens in the packaging bag 1 into a plate shape of a predetermined thickness, forming a metal powder-resin plate package 50. The opening 5 of the packaging bag 1 may be heat-sealed as needed. This prevents foreign matter from entering the packaging bag 1 during subsequent transportation, which could cause contamination or corrosion of the metal powder-resin plate 100. The predetermined thickness is preferably 0.1 to 10 mm, more preferably 0.3 to 1.0 mm.

[0077] The heating temperature for curing mixture P varies depending on the type of thermosetting resin contained in mixture P, but from the viewpoint of the heat resistance of the packaging bag, particularly the sealant layer, it is preferably 135°C or less, more preferably 100 to 130°C, and even more preferably 120 to 130°C.

[0078] Next, in the fourth step, as shown in Figure 3(e), the surface film 1 and the back film 2 of the packaging bag 1 are peeled and removed from the outer edge seal portion 4, which has easy-peel properties, to obtain a metal powder-resin plate 100, as shown in Figure 3(f).

[0079] [Pressing method] Fig. 4 is a process diagram of another example of a method for manufacturing a metal powder-resin plate by a pressing method. Fig. 4(a) to (f) are diagrams illustrating the process for manufacturing a metal powder-resin plate 100 from a mixture P of metal powder and a thermosetting resin.

[0080] First, in the first step, a mixture P of metal powder and thermosetting resin is placed in the center of a packaging bag 1, as shown in FIG. 4(a).

[0081] Next, in the second step, as shown in Figures 4(b) and 4(c), the mixture 1 contained in the packaging bag 1 is sandwiched between the press plates B of the press sealing machine, thereby pressing and stretching the mixture P within the packaging bag 1 to a predetermined thickness.

[0082] Subsequently, in the third step, the mixture P that has been pressed and spread inside the packaging bag 1 is heated together with the packaging bag 1 at a temperature of, for example, 125°C for 10 to 20 minutes to harden the mixture P. Here, the mixture P contained in the packaging bag 1 may be subjected to the heat hardening treatment while sandwiched between the press plates B, or may be subjected to the heat hardening treatment after being removed from the press plates B.

[0083] The heating temperature when curing the mixture P varies depending on the type of thermosetting resin contained in the mixture P, but is preferably 130°C or less, more preferably 100 to 130°C, and even more preferably 120 to 130°C, from the viewpoint of the heat resistance of the packaging bag, particularly the sealant layer. The pressure applied to the mixture by the press plate B varies depending on the type of thermosetting resin contained in the mixture P, but is preferably 100 kgf / cm. 2 More than 2000kgf / cm 2 It is preferable that:

[0084] As a result, as shown in Fig. 4(d), the mixture P is hardened into a plate shape of a predetermined thickness within the packaging bag 1 to form a metal powder-resin plate package 50. The opening 5 of the packaging bag 1 may be heat-sealed as needed. This prevents foreign matter from entering the packaging bag 1 during subsequent transportation, etc., which could cause contamination or corrosion of the metal powder-resin plate 100.

[0085] Next, in the fourth step, as shown in Figure 4(e), the surface film 1 and the back film 2 of the packaging bag 1 are removed by peeling off the outer edge seal portion 4, which has easy-peel properties, to obtain a metal powder-resin plate 100, as shown in Figure 4(f).

[0086] As described above, the manufacturing method of the metal powder-resin plate 100 of the present invention is such that the mixture P is contained in the packaging bag 1 and then molded and heat-cured, thereby manufacturing the metal powder-resin plate 100 while it is enclosed in the packaging bag 1. When using the metal powder-resin plate 100, the packaging bag 1 can be removed, which makes handling from the manufacturing process to transportation easy.

[0087] Furthermore, the produced metal powder-resin plate 100 can be stored in the packaging bag 1, i.e., in the state of the metal powder-resin plate package 50, until immediately before use, which significantly prevents the metal powder-resin plate 100 from becoming soiled or corroding over long periods of storage. Furthermore, by heat-sealing the opening 5 of the packaging bag 1 of the metal powder-resin plate package 50, the metal powder-resin plate 100 can be more effectively prevented from becoming soiled or corroded.

[0088] Furthermore, the manufacturing method of the metal powder-resin plate 100 of the present invention does not require the step of sandwiching a release film between the mixture as in the conventional technology described above, thereby improving the manufacturing efficiency of the metal powder-resin plate 100.

[0089] Furthermore, the manufacturing method of the metal powder-resin plate 100 of the present invention can determine the widthwise size of the metal powder-resin plate 100 without using a mold, based on the size of the packaging bag 1. Also, since the amount of mixture P to be added can be estimated from the size of the packaging bag 1, the amount of remaining mixture can be reduced.

[0090] Furthermore, the manufacturing method of the metal powder-resin plate 100 of the present invention uses a packaging film 10 whose outer edge seal portion 4 has easy-peel properties, so that the packaging bag 1 can be easily removed from the metal powder-resin plate package 50 to obtain the metal powder-resin plate 100.

[0091] Furthermore, the method for manufacturing the metal powder-resin plate 100 of the present invention does not require blending wax or the like into the mixture as in the prior art, and therefore prevents an increase in material costs.

[0092] As described above, the packaging bag 1 has a sealant layer 13 of the packaging film 10 that has releasability against the thermosetting resin of the mixture P, so that the hardened metal powder-resin plate 100 inside the packaging bag 1 can be easily peeled off from the packaging bag 1 (surface film 2, back film 3).

[0093] The packaging film 10 (surface film 2, back film 3) of the packaging bag 1 may be provided with an uneven shape by appropriate embossing or the like. This allows a desired uneven shape to be formed on the surface of the metal powder-resin plate 100 that is manufactured by molding and heat-curing treatment inside the packaging bag 1. For example, when the applicator method is used, the desired uneven shape can be imparted to the metal powder-resin plate 100 by providing an uneven shape corresponding to the contact surface of the applicator with the packaging bag 1. The uneven shape on the surface may be a groove shape.

[0094] Next, a metal powder-resin plate package manufactured by the method for manufacturing a metal powder-resin plate will be described.

[0095] <Metal powder-resin plate packaging> The metal powder-resin plate package 50 according to this embodiment is a metal powder-resin plate package containing a metal powder-resin plate formed by placing a mixture of metal powder and a thermosetting resin inside a bag and then heat-curing the mixture. As described above, by providing the sealant layer 13 having a predetermined sealing strength and peeling characteristics as the innermost layer, it is possible to effectively prevent the binder resin in the metal powder-resin plate 100 from adhering to a mold or the like after press molding or heat-curing.

[0096] <Uses of metal powder-resin plates> The metal powder-resin plate produced using the above-mentioned packaging bag can be used in a variety of applications, including as a raw material for magnetic refrigeration composite materials, inductors, sealing materials, electromagnetic wave shields (EMI shields), magnetic materials, and bonded magnets. [Example]

[0097] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these descriptions in any way.

[0098] [Example 1] A dry laminating adhesive (product name: RU40, manufactured by Rock Paint Co., Ltd., corresponding to adhesive layer 12) was applied at a rate of 3 g / m to the corona-treated surface of a biaxially stretched polyethylene terephthalate film (product name: E5100, manufactured by Toyobo Co., Ltd., thickness: 12 μm, corresponding to base layer 11). 2 The resulting laminate was applied in a dry coating amount of 1000 ppm, and then laminated with an easy-peel film (product name: CMPS 013C, manufactured by RM Tocello Co., Ltd., thickness: 50 μm, corresponding to sealant layer 13). The resulting laminate was aged at 40°C for 3 days to obtain a laminate (corresponding to packaging film 10). The easy-peel film surfaces were sealed on three sides using the resulting laminate under sealing conditions (150°C, 1 kgf, 1 second) to produce a flat pouch (corresponding to packaging bag 1) of 80 mm x 150 mm.

[0099] A mixture was obtained by mixing 80% by mass of iron oxide metal powder and 20% by mass of thermosetting epoxy resin. This mixture was placed in the bottom of a flat pouch (packaging bag 1). The mixture P was then stretched from the top of the pouch (packaging bag 1) toward the opening 5 using an applicator so that the thickness of the metal powder-resin plate was 0.6 mm. A plate was then formed to fit the pouch size. The resulting molded product was then heated at 120°C for 10 minutes without being opened from the flat pouch (packaging bag 1) to harden it, producing a cured plate (corresponding to metal powder-resin plate package 50) in the pouch. The front and back laminates (packaging films 10) were then peeled from the outer edge seal 4 of the flat pouch (packaging bag 1) to obtain a smooth metal powder-resin plate 100.

[0100] [Example 2] A mixture of metal powder and thermosetting resin was cured in the same manner as in Example 1, to obtain a smooth metal powder-resin plate, except that the easy-peel film of the flat pouch (packaging bag 1) was changed to TAF680C, manufactured by RM Tosero Co., Ltd., thickness: 50 μm, and the sealing conditions were changed to 160°C, 1 kgf, 1 second.

[0101] [Example 3] A mixture of 80% by mass of iron oxide metal powder and 20% by mass of thermosetting epoxy resin was placed in the center of the three-sided sealed flat pouch (packaging bag 1) of Example 1, and press molding was performed from above the flat pouch (packaging bag 1) so that the thickness of the metal powder-resin plate was 0.6 mm. The resulting molded product was heated and cured at 120°C for 10 minutes without opening the flat pouch (packaging bag), producing a cured plate contained in the pouch. The front and back laminates were then peeled from the plate at the seal of the flat pouch (packaging bag 1), yielding a smooth metal powder-resin plate.

[0102] [Comparative Example 1] Instead of using the laminate with the easy-peel film, a silicone-coated release PET film (Cerapeel MFA, manufactured by Toray Industries, Inc., thickness: 38 μm) was used to seal the coated surfaces together, but sealing was not possible. 80% by mass of iron oxide metal powder and 20% by mass of thermosetting epoxy resin were mixed, and the mixture was placed on the coated surface of the release PET film. The mixture was then spread over the film using an applicator to a thickness of 0.6 mm, forming a plate. The resulting molded product was then heated at 120°C for 10 minutes while sandwiched between the release films to harden it and produce a cured plate. The release films were then peeled off from the front and back plates to obtain a metal-resin plate.

[0103] Comparative Example 2 A flat pouch (packaging bag) was obtained that was sealed on three sides under the same sealing conditions as in Example 1 (180°C, 1 kgf, 1 second), except that the easy-peel film was changed to a CPP film (manufactured by SC RM Tosero Co., Ltd., thickness: 50 μm).

[0104] Next, similar to Example 1, 80% by mass of iron oxide metal powder and 20% by mass of thermosetting epoxy resin were mixed to obtain a mixture, which was then placed in the center of a flat pouch (packaging bag) and press-molded from above the flat pouch (packaging bag) so that the thickness of the metal powder-resin plate was 0.6 mm. The resulting molded product was heated and cured at 120°C for 10 minutes without being opened from the flat pouch (packaging bag), producing a cured plate contained in the flat pouch (packaging bag). When an attempt was made to peel the front and back laminates from the plate through the seal of the flat pouch (packaging bag), the film and plate resin were adhered, making peeling impossible.

[0105] Comparative Example 3 A flat pouch (packaging bag) was obtained that was sealed on three sides under the same sealing conditions (160°C, 1 kgf, 1 second) as in Example 1, except that the easy-peel film was replaced with an LLDPE film (TUS MC-S, manufactured by RM Tocello Co., Ltd., thickness: 50 μm). Next, similar to Example 1, 80% by mass of iron oxide metal powder and 20% by mass of thermosetting epoxy resin were mixed to obtain a mixture, which was placed in the center of the flat pouch (packaging bag) and press-molded so that there was a 5 mm clearance from above the flat pouch (packaging bag). When the obtained molded product was heated at 120°C for 10 minutes without being opened from the flat pouch (packaging bag), shrinkage and deformation of the pouch were observed, and a smooth plate could not be obtained.

[0106] [evaluation] <Seal strength> The seal strength was measured for the outer edge seal portion 4 of the packaging bag 1 of the Examples and Comparative Examples. Specifically, the outer edge seal portion of the packaging bag of the Examples and Comparative Examples was measured for the maximum load when peeled using a Tensilon tensile tester (RTC-1310A, manufactured by Orientec Co., Ltd.) at a temperature of 25°C and a relative humidity of 60% using a T-peel method (pulling speed 300 mm / min), and the average of N=3 was taken as the seal strength (N / 15 mm width). The evaluation results are shown in Table 1 (referred to as "Seal Strength" in Table 1).

[0107] <Peel strength> The peel strength between the sealant layer and the epoxy resin of the flat pouches (packaging bags) of the Examples and Comparative Examples was measured. Specifically, a laminate (packaging film constituting the packaging bag) was obtained in the same manner as in the Examples and Comparative Examples. The laminate was sandwiched between the easy-peel film side (or silicone-coated side, CPP film side, LLDPE film) and the epoxy resin alone (product name: Cemedine EP138) and molded to a thickness of 0.5 mm using the applicator method. The laminate was then heated at 120°C for 10 minutes to produce a film-coated plate. Then, using a Tensilon tensile tester (RTC-1310A manufactured by Orientec Co., Ltd.), the magnetic plate was chucked on one side and the release film on the other side at a temperature of 25°C and a relative humidity of 60%, and the load when peeled using a 180° peeling method (pulling speed 50 mm / min, chuck distance 100 mm) was measured under an atmosphere of N=3. The average of N=3 was taken as the peel strength (N / 15 mm width). The evaluation results are shown in Table 1 (in Table 1, they are indicated as "peel strength").

[0108] <Seal strength> In the examples and comparative examples, a cured plate was prepared in a pouch, and then the seal strength was measured when the front and back films were peeled off from the seal of the flat pouch (packaging bag). The measurement results are shown in Table 1.

[0109] <Peel strength> In the examples and comparative examples, a cured plate in a pouch was prepared, and then the releasability was confirmed when the flat pouch (packaging bag) was peeled from the plate. The measurement results are shown in Table 1. Examples 1 and 3 each show the results of two measurements.

[0110] <Appearance evaluation> In the examples and comparative examples, the appearance of the flat pouch (packaging bag) and metal powder-resin plate after the mixture of metal powder and thermosetting resin contained inside the bag was thermally cured was checked. The evaluation results are shown in Table 1 (in Table 1, they are labeled "Appearance"). Evaluation criteria ◯: No shrinkage or deformation of the pouch was observed, and a smooth plate was obtained. ×: Shrinkage and deformation of the pouch was observed, and a smooth plate could not be obtained.

[0111] [Table 1]

[0112] Table 1 shows that by manufacturing metal powder-resin plates using packaging bags having a sealant film (sealant layer 13) with the specified seal strength and peel characteristics, metal powder-resin plates of the specified shape and thickness can be efficiently manufactured. [Explanation of symbols]

[0113] 1: Packaging bag 2: Surface film 3: Back film 4: Outer edge seal 5: Opening 10: Packaging film 11: Base material layer 12: Adhesive layer 13: Sealant layer 50: Metal powder-resin plate packaging 100: Metal powder-resin plate

Claims

1. A packaging bag for producing a metal powder-resin plate, which is formed by storing a mixture of metal powder and a thermosetting resin inside the bag and thermosetting the mixture, The packaging bag has a front film and a back film facing each other, an opening, and an outer edge seal portion extending along the outer edge of the packaging bag, The seal strength of the outer edge seal portion is 2N / 15mm width or more and 15N / 15mm width or less, The packaging bag has a sealant layer that forms the innermost layer of the packaging bag and is made of a thermoplastic resin, and has a peel strength with a thermosetting resin of 1 N / 15 mm width or less, as measured by the following test method. <Test Method> The sealant layer of the packaging bag and the thermosetting resin are bonded by heating at 120°C for 10 minutes, and the load when peeled off using a 180°C peeling method (tensile speed 50 mm / min) in a 25°C atmosphere is measured.

2. The packaging bag according to claim 1 , wherein the sealant layer contains more than 50% by mass of a propylene-based polymer and less than 50% by mass of an ethylene-based polymer.

3. The packaging bag according to claim 1 , wherein the front film and the back film are laminated films each including a base material layer and the sealant layer.

4. The packaging bag according to claim 1 , wherein the thermosetting resin is an epoxy resin.

5. A metal powder-resin plate package containing a metal powder-resin plate formed by placing a mixture of metal powder and a thermosetting resin inside the packaging bag according to any one of claims 1 to 4 and then thermosetting the mixture.

6. A first step of placing a mixture of metal powder and a thermosetting resin inside a packaging bag; a second step of adjusting the mixture to a predetermined thickness; and a third step of heat-curing the packaging bag containing the mixture to produce a metal powder-resin plate package. The packaging bag has a front film and a back film facing each other, an opening, and an outer edge seal portion extending along the outer edge of the packaging bag, The seal strength of the outer edge seal portion is 2N / 15mm width or more and 15N / 15mm width or less, The method for producing a metal powder-resin plate, wherein the sealant layer constituting the innermost layer of the packaging bag is made of a thermoplastic resin, and the peel strength with respect to the thermosetting resin measured by the following test method is 1 N / 15 mm width or less. <Test Method> The sealant layer of the packaging bag and the thermosetting resin are bonded by heating at 120°C for 10 minutes, and the load when peeled off using a 180°C peeling method (tensile speed 50 mm / min) in a 25°C atmosphere is measured.

7. 7. The method for manufacturing a metal powder-resin plate according to claim 6, further comprising a fourth step of peeling the front surface film and the back surface film from the outer edge seal portion after the third step.

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