Microwave heat generating film, microwave heat generating package, and method for producing microwave heat generating film

Abstract

To provide a microwave heat generating film which exhibits high vapor permeability when irradiated with low-power microwaves and enables control of a location where vapor permeation holes are formed.SOLUTION: A microwave heat generating film according to the present invention has at least one first microwave heating region having a first area and one or more second microwave heating regions having a second area, in which the first area is larger than the second area in a plan view, and the first microwave heating region and the second microwave heating region each has a surface resistivity of 5 Ω / square to 10,000 Ω / square.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a microwave heating film, a microwave heating package, and a method for producing a microwave heating film. [Background technology]

[0002] A package that contains food ingredients may be heated and cooked in a microwave oven while the food ingredients are sealed inside. Therefore, by using a microwave heating composition containing a microwave heating material that generates heat by microwaves in the package, steam from the food ingredients heated by microwaves can be released from the package, allowing the package to exhibit vapor permeability. The means for allowing steam to escape from the package may be a heat-sealed portion or an opening may be provided in the upper portion of the package.

[0003] Regarding the central opening, a microwave heating package has been disclosed in which a film-like microwave heating package covering a container has a coating layer that generates heat when exposed to microwaves, and the coating layer is heated by exposure to microwaves, forming an opening for steam to escape (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional microwave heat generating films, the area of ​​the microwave heat generating layer formed is small, so high-output microwave irradiation is required to cause vaporization, which poses the problem of low vaporization. On the other hand, if a microwave heating layer is formed over a wide area by solid coating in order to ensure vapor permeability, the vapor permeability holes will be unevenly formed, which will not look good and will cause pieces of the film to fall into the food. An object of one aspect of the present invention is to provide a microwave heating film that exhibits high vapor permeability when irradiated with low-power microwaves and that allows the location of vapor permeation holes to be controlled. [Means for solving the problem]

[0005] One aspect of the present invention is at least one first microwave heating region having a first area; and one or more second microwave heating regions having a second area; The first area is larger than the second area in a plan view, The first microwave heating region and the second microwave heating region each have a surface resistivity of 5 Ω / □ or more and 10,000 Ω / □ or less. It is. Effect of the Invention

[0006] One aspect of the present invention is to provide a microwave heating film that exhibits high vapor permeability when irradiated with low-power microwaves and that allows the location of vapor permeation holes to be controlled. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view showing an example of a microwave heating film according to an embodiment. [Diagram 2] FIG. 4 is a schematic cross-sectional view showing another example of the microwave heating film according to an embodiment. [Diagram 3] FIG. 4 is a schematic cross-sectional view showing another example of the microwave heating film according to an embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing another example of the microwave heating film according to an embodiment. [Diagram 5] FIG. 4 is a schematic cross-sectional view showing another example of the microwave heating film according to an embodiment. [Figure 6] 2 is a schematic plan view showing an example of the shape of a microwave heating layer in a microwave heating film according to an embodiment. FIG. [Figure 7] FIG. 4 is a schematic plan view showing another example of the shape of the microwave heating layer in the microwave heating film according to an embodiment. [Figure 8]FIG. 4 is a schematic plan view showing another example of the shape of the microwave heating layer in the microwave heating film according to an embodiment. [Figure 9] FIG. 4 is a schematic plan view showing another example of the shape of the microwave heating layer in the microwave heating film according to an embodiment. [Figure 10] FIG. 4 is a schematic plan view showing another example of the shape of the microwave heating layer in the microwave heating film according to an embodiment. [Figure 11] FIG. 4 is a schematic plan view showing another example of the shape of the microwave heating layer in the microwave heating film according to an embodiment. [Figure 12] FIG. 4 is a schematic plan view showing another example of the shape of the microwave heating layer in the microwave heating film according to an embodiment. [Figure 13] FIG. 4 is a schematic plan view showing another example of the shape of the microwave heating layer in the microwave heating film according to an embodiment. [Figure 14] FIG. 4 is a schematic plan view showing another example of the shape of the microwave heating layer in the microwave heating film according to an embodiment. [Figure 15] FIG. 2 is a perspective view showing an example of a microwave heating package according to one embodiment. [Figure 16] 3 is a schematic plan view showing the shape of a microwave heating layer in a microwave heating film according to Comparative Example 1. FIG. [Figure 17] 10 is a schematic plan view showing the shape of a microwave heating layer in a microwave heating film according to Comparative Example 2. FIG. [Figure 18] 11 is a schematic plan view showing the shape of a microwave heating layer in a microwave heating film according to Comparative Example 5. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described in detail. In this specification, the term "vaporize" means that a vapor escape hole (sometimes referred to as a "vapor passage hole" in this specification) is formed.

[0009] <Microwave heating film> A microwave heating film according to one embodiment of the present invention will be described. The microwave heating film has a substrate, at least one first microwave heating region having a first area, and one or more second microwave heating regions having a second area, and may further have a sealant, an adhesive layer, a printing ink layer, an anchor coat layer, an overcoat layer, other layers, etc., as necessary.

[0010] An example of the microwave heating film according to an embodiment is shown in FIG. 1 to FIG.

[0011] As shown in FIG. 1, the microwave heating film 100 comprises a substrate 11 and a microwave heating layer 1 having a first microwave heating region and a second microwave heating region, laminated in this order: substrate 11 and microwave heating layer 1.

[0012] As shown in FIG. 2, the microwave heat generating film 101 includes a base material 12 having a sealability and a microwave heat generating layer 1, which are laminated in this order.

[0013] 3, the microwave heating film 102 includes a substrate 11, a microwave heating layer 1, and a sealant 13, which are laminated in the following order: sealant 13, substrate 11, and microwave heating layer 1. The microwave heating film 102 may have the microwave heating layer 1 provided on a portion of one main surface of the substrate 11, and the sealant 13 provided on the entire surface of the other main surface of the substrate 11. The microwave heating layer 1 may be provided on the entire surface of one main surface of the substrate 11, and the sealant 13 may be provided on a portion of the other main surface of the substrate 11.

[0014] As shown in Fig. 4, the microwave heat generating film 103 may have the base material 11 and the microwave heat generating layer 1 laminated in the reverse order to that of the microwave heat generating film 102 shown in Fig. 1. That is, the microwave heat generating film 103 may have the base material 11, the microwave heat generating layer 1 and the sealant 13 laminated in the order of the sealant 13, the microwave heat generating layer 1 and the base material 11.

[0015] 5, the microwave heat generating film 104 may be obtained by providing a microwave heat generating layer 1 on the side of the sealant 13 opposite to the substrate 11 side in the microwave heat generating film 102 shown in FIG 1. That is, the microwave heat generating film 104 may include the substrate 11, the microwave heat generating layer 1, and the sealant 13 laminated in the order of the microwave heat generating layer 1, the sealant 13, and the substrate 11.

[0016] [First microwave heating region and second microwave heating region] The first microwave heating region and the second microwave heating region are layers formed using a microwave heating composition (hereinafter, sometimes referred to as "microwave heating layers"). One aspect of the present invention is a microwave heating film having at least one first microwave heating region having a first area and one or more second microwave heating regions having a second area, wherein the first area is larger than the second area in a planar view, and the first microwave heating region and the second microwave heating region each have a surface resistivity of 5 Ω / □ or more and 10,000 Ω / □ or less. In addition, the second microwave heating region is located in the vicinity of the first microwave heating region. By having the second microwave heating region located in the vicinity of the first microwave heating region, heat dissipation from the first microwave heating region that is heated by microwaves is suppressed, and the temperature of the target region is preferentially increased. In other words, in the present invention, "in the vicinity" means a distance at which the heat dissipation from the first microwave heating region is suppressed by the second microwave heating region.

[0017] 6 to 14 are schematic plan views showing examples of the shape of a microwave heating layer in a microwave heating film according to an embodiment.

[0018] In the embodiment shown in FIG. 6, the microwave heating layer 1 has one first microwave heating region 2 having a first area, and multiple (eight) second microwave heating regions 3 having a second area at positions a predetermined distance to the left and right of the first microwave heating region 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. The target region 5 is the region in which it is desired to form vaporization holes. In the embodiment shown in FIG. 6, the first microwave heating region is rectangular in shape and the second microwave heating region is rectangular in shape. In the embodiment shown in FIG. 6, the shortest distance between the first microwave heating area and the second microwave heating area is four. When there are a plurality of first microwave heating regions 2, the first area means the area of ​​one first microwave heating region. When there are a plurality of second microwave heating regions 3, the second area means the area of ​​one second microwave heating region.

[0019] In the embodiment shown in Fig. 7, the microwave heating layer 1 has one first microwave heating region 2 having a first area, and a plurality (10) of second microwave heating regions 3 having a second area at positions a predetermined distance to the left and right and above and below the first microwave heating region 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. In the embodiment shown in FIG. 7, the first microwave heating region is rectangular in shape and the second microwave heating region is rectangular in shape. In the embodiment shown in FIG. 7, the shortest distance between the first microwave heating area and the second microwave heating area is four.

[0020] In the embodiment shown in Fig. 8, the microwave heating layer 1 has one first microwave heating region 2 having a first area, and a plurality (10) of second microwave heating regions 3 having a second area at positions a predetermined distance to the left and right of the first microwave heating region 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. In the embodiment shown in FIG. 8, the first microwave heating region is rectangular in shape and the second microwave heating region is circular in shape. In the embodiment shown in FIG. 8, the shortest distance between the first microwave heating area and the second microwave heating area is four.

[0021] In the embodiment shown in Fig. 9, the microwave heating layer 1 has one first microwave heating region 2 having a first area, and multiple (four) second microwave heating regions 3 having a second area at positions a predetermined distance away on either the left or right side of the first microwave heating region 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. In the embodiment shown in FIG. 9, the first microwave heating region is rectangular in shape and the second microwave heating region is rectangular in shape. In the embodiment shown in FIG. 9, the shortest distance between the first microwave heating area and the second microwave heating area is four.

[0022] In the embodiment shown in Fig. 10, the microwave heating layer 1 has a plurality (two) of first microwave heating regions 2 having a first area, and a plurality (eight) of second microwave heating regions 3 having a second area at positions a predetermined distance to the left and right of the first microwave heating regions 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. In the embodiment shown in FIG. 10, the first microwave heating region is rectangular in shape and the second microwave heating region is rectangular in shape. In the embodiment shown in FIG. 10, the shortest distance between the first microwave heating area and the second microwave heating area is four.

[0023] In the embodiment shown in Fig. 11, the microwave heating layer 1 has one first microwave heating region 2 having a first area, and multiple (eight) second microwave heating regions 3 having a second area at positions a predetermined distance to the left and right of the first microwave heating region 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. In the embodiment shown in FIG. 11, the shape of the first microwave heating region is a rectangle having three recesses on each of the left and right sides, and the shape of the second microwave heating region is also a rectangle. In the embodiment shown in FIG. 11, the shortest distance between the first microwave heating area and the second microwave heating area is four.

[0024] In the embodiment shown in Fig. 12, the microwave heating layer 1 has one first microwave heating region 2 having a first area, and multiple (eight) second microwave heating regions 3 having a second area at positions a predetermined distance to the left and right of the first microwave heating region 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. In the embodiment shown in FIG. 12, the first microwave heating region is elliptical in shape and the second microwave heating region is rectangular in shape. In the embodiment shown in FIG. 12, the shortest distance between the first microwave heating area and the second microwave heating area is four.

[0025] In the embodiment shown in Fig. 13, the microwave heating layer 1 has one first microwave heating region 2 having a first area, and a plurality (12) of second microwave heating regions 3 having a second area at positions a predetermined distance to the left and right of the first microwave heating region 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. In the embodiment shown in FIG. 13, the shape of the first microwave heating region is rectangular and the shape of the second microwave heating region is polygonal (triangle). In the embodiment shown in FIG. 13, the shortest distance between the first microwave heating region and the second microwave heating region is four.

[0026] In the embodiment shown in Fig. 14, the microwave heating layer 1 has a plurality (two) of first microwave heating regions 2 having a first area, and a plurality (twelve) of second microwave heating regions 3 having a second area at positions a predetermined distance to the left and right of the first microwave heating regions 2 in a planar view. The first area is larger than the second area in a planar view. By having the first microwave heating region 2 and the second microwave heating region 3, the microwave heating layer 1 can form vaporization holes in a target region 5 that is near the second microwave heating region on the first microwave heating region 2. In the embodiment shown in FIG. 14, the first microwave heating region is rectangular in shape and the second microwave heating region is rectangular in shape. In the embodiment shown in FIG. 14, the shortest distance between the first microwave heating area and the second microwave heating area is four.

[0027] The number of first microwave heating regions is not particularly limited and can be selected appropriately depending on the purpose. For example, there may be one as shown in Figures 6 to 9 and Figures 11 to 13, two as shown in Figures 10 and 14, or three or more.

[0028] The number of second microwave heating regions is not particularly limited and can be appropriately selected depending on the purpose. For example, there may be one, or two or more as shown in Figs.

[0029] The shapes of the first microwave heating region 2 and the second microwave heating region 3 are not particularly limited and can be appropriately selected depending on the purpose. Examples of shapes include circular, elliptical, polygonal, and wavy shapes as shown in Figures 6 to 14.

[0030] The first microwave heating region 2 and the second microwave heating region 3 each have a surface resistivity of 5 Ω / □ or more and 10,000 Ω / □ or less, preferably 5 Ω / □ or more and 5,000 Ω / □ or less, and more preferably 5 Ω / □ or more and 2,500 Ω / □ or less. When the surface resistivity is 5 Ω / □ or more and 10,000 Ω / □ or less, microwaves are absorbed and the microwave heating region generates heat. When the surface resistivity is less than 5 Ω / □, the microwave reflection effect is large, so microwaves cannot be absorbed and no heat is generated. On the other hand, when the surface resistivity is more than 10,000 Ω / □, the amount of microwaves that can be absorbed is small and no heat is generated. It is preferable that the surface resistivity of the first microwave heat generating region and the surface resistivity of the second microwave heat generating region are the same, which allows the same microwave heat generating ink to be used, simplifying the manufacturing process.

[0031] The method for measuring the surface resistivity is not particularly limited and can be appropriately selected depending on the purpose. For example, the surface resistivity can be measured using a two-terminal resistance measuring instrument (tester), a four-terminal resistance measuring instrument, or the like.

[0032] The shortest distance 4 between the first microwave heating area 2 and the second microwave heating area 3 is preferably 100 mm or less at most.

[0033] The film thickness of the first microwave heating region 2 and the second microwave heating region 3 is preferably 0.01 μm or more and 100 μm or less, and more preferably 0.05 μm or more and 10 μm or less, which increases the blocking resistance of the coating having the microwave heating layer.

[0034] The length of the first microwave heating region 2 in the longitudinal direction is preferably at least twice the length of the second microwave heating region 3 in the longitudinal direction.

[0035] When the microwave heating layer has a plurality of second microwave heating regions, the plurality of second microwave heating regions are preferably positioned along the longitudinal direction of the first microwave heating region. Moreover, the plurality of second microwave heating regions are preferably located on the left and right sides of the first microwave heating region in a plan view.

[0036] The microwave heating layer can be formed by applying a microwave heating composition to at least one of the main surfaces of the substrate. The application method is not particularly limited, and a general application method may be used.

[0037] [[Microwave heating composition]] The microwave heating composition contains a conductive material, and further contains other components as necessary.

[0038] (Conductive materials) Examples of the conductive material include inorganic materials such as carbon black and graphite, metals such as silver, aluminum, zinc oxide, tin oxide, and iron oxide, alloys or metal oxides, and organic materials such as thiophenes, anilines, and pyrroles. Among these, from the viewpoint of transparency, organic materials are preferred, and thiophenes are more preferred.

[0039] (Other Ingredients) The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples of the other components include dopants, solvents, coloring materials, solvents, waxes, pigment dispersants, other resins, and crosslinking agents.

[0040] [Base material] The substrate is preferably at least one selected from paper, plastic film or sheet, and laminates obtained by imparting sealing properties thereto. Examples of the plastic film or sheet include polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin films such as polyethylene, polypropylene, and ethylene-vinyl acetate, polystyrene films, alcohol-based films such as ethylene-vinyl alcohol and polyvinyl alcohol, polyamide films or barrier polyamide films with a barrier layer disposed between them, cellophane, moisture-proof cellophane, transparent vapor-deposited polyester films or transparent vapor-deposited polyamide films obtained by providing vapor-deposited layers of alumina, silica, etc. on PET films or polyamide films, and various coating films coated with polyvinylidene chloride resin, polyvinyl alcohol resin, polyacrylic acid resin, easy-adhesive resin, etc. These may be stretched or unstretched, and one or more types may be laminated. Appropriate ones can be selected in consideration of mechanical strength, dimensional stability, etc.

[0041] In order to improve the adhesion of the microwave heat generating composition to the coating surface of the substrate, a corona treatment, low temperature plasma treatment, flame treatment, solvent treatment, coating treatment or the like may be applied or may be previously applied.

[0042] Furthermore, the substrate may be a laminate of a thermoplastic resin or the like by a method such as dry lamination, non-solvent lamination, or extrusion lamination, or a method of bonding via an adhesive, or may be an appropriate combination of these. It may also be a uniaxially stretched film, an easy-to-cut film, a stretch film, or a shrink film.

[0043] The substrate may be a laminate having a sealability. Examples of a method for providing the sealability include lamination of a known sealant film or sheet, resin coating by extrusion lamination, etc., and a layer having a sealability provided by such a method is also called a sealant.

[0044] The substrate may be scratched in advance.

[0045] The thickness of the substrate is not particularly limited as long as it is within a range that does not impair printability, windability, etc., but is preferably 5 μm to 300 μm, and more preferably 6 μm to 250 μm.

[0046] [Sealant] The sealant is preferably a layer containing a resin having sealing properties, and examples of resins that can be used include polyethylene resins such as LDPE, LLDPE, HDPE, and metallocene polyethylene, polypropylene resins, ethylene-vinyl acetate copolymers, ionomer resins, ethylene-acrylic acid copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-propylene copolymers, methylpentene polymers, acid-modified polyolefin resins obtained by modifying polyethylene or polypropylene with maleic acid, fumaric acid, or the like, and thermoplastic resins such as polystyrene resins. These resins may be used alone or in combination.

[0047] A film containing these resins or a laminate in which a plurality of films are laminated may be formed by lamination using a dry lamination method, a wet lamination method, a non-solvent lamination method, a thermal lamination method, or the like, resin coating using extrusion lamination processing, coating with a heat sealing agent, or bonding via a hot melt adhesive, etc. Furthermore, the film or laminate containing these resins does not necessarily have to be formed on the entire surface, and may be formed only on the portion to be sealed.

[0048] Examples of the film include polyolefin films such as polyethylene, polypropylene, a mixed resin of polyethylene and polypropylene, an ethylene-vinyl acetate copolymer resin, an ethylene-(meth)acrylic acid copolymer resin, an ethylene-methyl (meth)acrylate copolymer resin, an ethylene-ethyl (meth)acrylate copolymer resin, and an ethylene-vinyl alcohol copolymer resin.

[0049] Examples of resins that can be used for resin coating by extrusion lamination or hot melt adhesives include thermoplastic resins such as polyethylene resins such as LDPE, LLDPE, and HDPE, polypropylene resins, ethylene-vinyl acetate copolymers, ionomer resins, ethylene-acrylic acid copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-propylene copolymers, methylpentene polymers, acid-modified polyolefin resins obtained by modifying polyethylene or polypropylene with maleic acid, fumaric acid, or the like, and polystyrene resins. These resins may be used alone or in combination of two or more.

[0050] The thickness of the sealant is not particularly limited, but from the viewpoints of sealing property, cost, and productivity, it is preferable that the thickness be 2 μm to 200 μm for a film, 1 μm to 100 μm for a resin coating by extrusion lamination, 0.1 μm to 10 μm for a coating of a heat sealing agent, and 1 μm to 50 μm for a coating of a hot melt adhesive.

[0051] [Adhesive layer] The adhesive layer can be provided, for example, between a substrate and another substrate, or between a substrate and a sealant. The adhesive layer is a layer formed to bond two layers together using an adhesive or pressure-sensitive adhesive (including wax and hot melt) that has adhesive or tackiness.

[0052] Examples of the resin forming the adhesive layer include the above-mentioned resin having sealing properties used in forming the sealant, urethane resin, butadiene resin, polyethyleneimine resin, isocyanate resin, chelate, etc. In addition, a commercially available adhesive can be used as the resin forming the adhesive layer. Furthermore, the adhesive may be a one-liquid type adhesive in which the base agent and the curing agent are mixed, or a two-liquid type adhesive in which the base agent and the curing agent are separate. When the resin forming the adhesive layer is a two-liquid type adhesive, the mixing ratio of the base agent and the curing agent is appropriately adjusted and mixed for use.

[0053] [Printing ink layer] For the printing ink layer, a normal printing ink can be used, and can be appropriately selected depending on the substrate. From the viewpoint of printability and versatility, the printing ink is preferably a gravure ink such as a urethane resin, a vinyl chloride-vinyl acetate copolymer resin, nitrocellulose, a polyamide resin, an acrylic resin, a chlorinated polypropylene resin, or a polyester resin. These resins may be one type or a combination of two or more types of gravure ink. In addition, when two or more colors of gravure ink are used, they do not need to be inks of the same resin system, and inks of different resin systems can be used appropriately.

[0054] [Anchor coat layer] The anchor coat layer may be transparent, or may be formed using an anchor coat agent containing a coloring material, so that various color variations and color designs can be obtained. The anchor coat layer may be provided between the substrate and the microwave heating layer.

[0055] [Overcoat layer] The overcoat layer can be formed using an overcoat agent, an overcoat varnish, an overprint varnish, or the like.

[0056] [Other layers] Examples of other layers include OPP film, ONY film, PET film, EVOH film, PVA film, cellophane film, barrier nylon film, oriented polyethylene film, (modified) polyacrylic acid coated film, PVA coated film, transparent vapor deposition films in which inorganic oxides such as aluminum oxide and silicon oxide are vapor deposited on a substrate such as a biaxially oriented polyethylene terephthalate film, transparent barrier films (K-coats) in which a base film such as OPP, ONY, PET, or cellophane is coated with PVDC (polyvinylidene chloride), and barrier films in which an ethylene-vinyl alcohol copolymer resin is sandwiched between OPP films or NY films and laminated. It is preferable to provide these films on the other side of the microwave heating layer.

[0057] <Method of manufacturing microwave heating film> A microwave heating film according to one embodiment includes a step of forming at least one first microwave heating region having a first area on at least one side of a substrate (a step of forming a first microwave heating layer), and a step of forming one or more second microwave heating regions having a second area in the vicinity of the first microwave heating region (a step of forming a second microwave heating layer).

[0058] The step of forming the first microwave heating layer and the step of forming the second microwave heating layer are preferably printing steps of forming a microwave heating composition. The printing process is preferably at least one selected from the group consisting of silk screen printing, gravure printing, offset printing, flexographic printing, roller coater, brush coating, spraying, knife jet coater, inkjet, etc. Among them, from the viewpoint of high quality and productivity, gravure printing, flexographic printing, inkjet, or silk screen printing is preferably used, and application by gravure printing is more preferable, and gravure printing using a multicolor gravure printer is even more preferable. This allows the microwave heat generating layer to be provided in multiple locations and can also be overprinted, making it easy to control the openability and heat generation of the steam escape opening.

[0059] Alternatively, a substrate having one or more laminated layers may be prepared using a lamination method (overprinting of microwave heat generating compositions), and then a microwave heat generating layer may be formed on one main surface of the substrate by various printing methods. After a microwave heat generating layer is formed on one main surface of the substrate by various printing methods, another substrate may be formed on the other main surface of the substrate by the lamination method described above. Alternatively, a microwave heat generating layer may be formed on both sides of the substrate.

[0060] When an overcoat layer is provided on the microwave heating layer, the overcoat layer can be formed using an overcoat agent, overcoat varnish, overprint varnish, or the like.

[0061] In the microwave heating film according to one embodiment, the printing process in which the microwave heating layer, the printing ink layer, and the anchor coat layer are formed may be a gravure printing method using one or more units of a multi-color gravure printer. This allows the microwave heating layer, the printing ink layer, the anchor coat layer, etc. to be continuously formed on the substrate in-line, and the microwave heating film can be easily manufactured in a series of steps (one pass) at low cost. In addition, the openability and heat generation of the steam escape opening can be easily controlled. When continuous in-line formation is not possible due to constraints such as the specifications of the gravure printer, the printing environment, and the equipment, the formation may be performed offline (outline).

[0062] Furthermore, in the case of a printing process using the gravure printing method, when a microwave heating layer is formed, if a 100% dot area rate results in excessive heat generation or depending on the required degree of openability of the steam escape opening, the openability and heat generation can be easily controlled by lowering the area rate, adjusting the plate depth, or adjusting the dilution rate.

[0063] The microwave heating layer may be formed only on the portion to be opened, or may be formed on the entire surface. Also, different coating patterns such as designs or motifs may be formed depending on the shape of the steam escape opening and the required degree of openability.

[0064] In addition, the printing process is preferably a gravure printing method in which one or more colors of gravure ink are formed, and a printed ink layer can be formed optionally on the opposite side of the microwave heating layer, between the substrate and the microwave heating layer, or between the microwave heating layer and the anchor coat layer, for example.

[0065] Furthermore, the printing process is preferably a gravure printing method using a multi-color gravure printer. The microwave heating layer is almost uncolored and transparent, so that the printing ink layer can be formed in-line at the same time without interfering with other information such as a pattern, and various color variations and color designs can be obtained. For example, the design of the package can be added to enhance the purchasing appeal effect, to display information on the opening location, opening method, and warnings, and to add information such as the company name, logo, product name, character, contents, ingredient display, application method, campaign announcement, how to eat or use, date, place of origin, and winning lottery.

[0066] The method may also include a forming process in which an intermediate layer, an anchor coat layer, an overcoat layer, etc. are formed. These layers are not particularly limited as long as they are formed by known processes such as lamination or coating.

[0067] Each composition, such as a microwave heat generating composition, a printing ink, and an anchor coating agent, can be produced by a known method by uniformly dissolving or dispersing a conductive organic compound, a resin, a pigment, a sealing resin, various additives, etc., in a solvent. For dissolving or dispersing, various stirrers or dispersers such as a dissolver, a roll mill, a ball mill, a bead mill, a sand mill, an attritor, a paint shaker, an agitator, a Henschel mixer, a colloid mill, a pearl mill, an ultrasonic homogenizer, a wet jet mill, a kneader, a homomixer, etc., can be used. These devices may be used alone or in combination of two or more. When air bubbles or coarse particles are contained in each composition, they deteriorate the printability and the quality of the printed matter, so it is preferable to remove them using a known filter, centrifuge, etc.

[0068] The viscosity of each of the above compositions is not particularly limited as long as it does not interfere with printing. In consideration of the manufacturability and handling of each composition, it is preferable that the viscosity is 10 mPa·s to 1000 mPa·s at 25°C. Furthermore, for gravure printing inks, it is more preferable that the viscosity is 10 mPa·s to 500 mPa·s.

[0069] The viscosity can be measured using a commercially available viscometer such as a Brookfield viscometer.

[0070] The microwave heat generating film according to one embodiment includes a microwave heat generating layer, and the microwave heat generating layer includes the microwave heat generating composition according to the above-mentioned one embodiment. In the microwave heat generating film according to one embodiment, the microwave heat generating layer generates heat by microwave irradiation, and when the microwave heat generating layer is overlapped with a heat seal portion, an opening can be formed from the heat seal portion by shrinking the film. Furthermore, when the microwave heat generating layer is provided in the center portion of the microwave heat generating film, an opening can be easily formed from the center portion by breaking the microwave heat generating film. Thus, the microwave heat generating film according to one embodiment has excellent substrate binding properties and water resistance, and generates heat by microwave irradiation during heating, so that an opening can be easily formed in the microwave heat generating film, and the film can exhibit high vapor permeability.

[0071] Since the microwave heating film according to one embodiment has the above-mentioned properties, it can be suitably used as a microwave heating film for packaging, and can be particularly effectively used as a microwave heating film for packaging that allows steam to escape.

[0072] <Microwave heating packaging> A microwave heating package according to one embodiment includes the microwave heating film according to the above-described embodiment, and includes a microwave heating layer formed on at least a portion of the microwave heating film.

[0073] The microwave heating package may be in any form commonly used for microwave heating sheet applications, such as two-sided seal, three-sided seal, four-sided seal, pillow seal, standing pouch, envelope seal, gusset, melt-cut seal, tube, caramel packaging, overhold, fin seal, manju packaging, twist, rocket, Tetra Pak (registered trademark), gable top, brick, shibori, cup, tray, bottle, brick, container, box, case, food box, cover, lid, cap, lid material, label, sheet, etc.

[0074] The method for producing a microwave heating package preferably includes a forming step of forming the package using a microwave heating film.

[0075] In the forming step, the microwave heat generating film may be formed into a package. One microwave heat generating film may be folded back and both ends sealed to form a bag. Alternatively, two microwave heat generating films may be stacked facing each other and both ends sealed to form a bag.

[0076] In addition, the forming step may involve covering the container with a microwave heating film and forming it into a package.

[0077] The forming process may use a method used in forming general packaging bodies such as two-sided seal, three-sided seal, four-sided seal, pillow seal, standing pouch, envelope sealing, gusset, melt-cut seal, tube, caramel packaging, overhold, fin seal, bun packaging, twist, rocket, Tetra Pak (registered trademark), gable top, brick, shibori, cup, tray, bottle, brick, container, box, case, food box, cover, lid, cap, lid material, label, sheet, etc.

[0078] An example of the configuration of a microwave heating package according to one embodiment is shown in FIG.

[0079] FIG. 15 shows an example of a microwave heat generating package 200 using the microwave heat generating film 100 according to one embodiment. The microwave heating package 200 is a packaging container in which a microwave heating film 100 and a container 202 are heat-sealed at a heat seal portion 201, and is an oblique view in which the microwave heating film 100 is arranged so that the microwave heating layer 1 is positioned so as not to be aligned perpendicular to the heat seal portion 201 in a plan view. In FIG. 15, the container 202 has a rectangular parallelepiped shape, but the shape may be changed to any shape, such as a cylinder, a cube, or a triangular prism, depending on the contents and design.

[0080] The microwave heating package according to one embodiment includes a microwave heating layer, and the microwave heating layer includes the microwave heating composition according to the above-mentioned embodiment. In the microwave heating package according to one embodiment, the microwave heating layer generates heat by irradiation with microwaves during heating, and when the microwave heating layer is superimposed on the heat-sealed portion, an opening is easily formed from the heat-sealed portion by shrinking of the film. Furthermore, when the microwave heating layer is provided in the center of the microwave heating film, an opening is easily formed from the center by breaking the microwave heating film. Thus, the microwave heating film according to one embodiment has excellent substrate binding properties and water resistance, and generates heat by irradiation with microwaves during heating, so that an opening is easily formed in the microwave heating package, and the film can exhibit high vapor permeability.

[0081] Since the microwave heating package according to one embodiment has the above-mentioned characteristics, it can be suitably used as a package that generates heat using microwaves, for example, as a package for heating in a microwave oven.

[0082] The microwave heat generating package according to one embodiment can have excellent substrate adhesion and water resistance, and high vapor permeability, and therefore can be suitably used, for example, as a package in which holes are formed by microwave irradiation. The microwave heat generating package according to one embodiment can also be suitably used, for example, as a cooking sheet in which food is browned by microwave irradiation.

[0083] As described above, the embodiment has been described, but the above embodiment is presented as an example, and the present invention is not limited to the above embodiment. The above embodiment can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. EXAMPLES

[0084] The embodiments will be described in more detail below with reference to examples and comparative examples, but the embodiments are not limited to these examples and comparative examples.

[0085] <Production of microwave heat generating composition> [Production Example 1] Microwave heating composition 1 was prepared by mixing 40 parts by mass of a carbon black dispersion (9510MW, manufactured by Tokushiki Co., Ltd.), which is a conductive material, with 1.5 parts by mass of an acrylic resin emulsion (MYK-2252, manufactured by Takamatsu Oil Co., Ltd.) and 2.0 parts by mass of ethanol.

[0086] [Production Example 2] Microwave heat generating composition 2 was produced by the same method as in Production Example 1, except that the acrylic resin emulsion was changed from 1.5 parts by mass to 7.5 parts by mass, and the ethanol was changed from 2.0 parts by mass to 12 parts by mass.

[0087] [Production Example 3] Microwave heat generating composition 3 was produced by the same method as in Production Example 1, except that the acrylic resin emulsion was changed from 1.5 parts by mass to 15 parts by mass, and the ethanol was changed from 2.0 parts by mass to 12 parts by mass.

[0088] [Production Example 4] Microwave heat generating composition 4 was produced by the same method as in Production Example 1, except that the acrylic resin emulsion was changed from 1.5 parts by mass to 26 parts by mass, and the ethanol was changed from 2.0 parts by mass to 12 parts by mass.

[0089] <Production of microwave heating film> [Example 1] The microwave heat generating composition 1 of Production Example 1 was applied to the sealant using a gravure printer in the coating shape shown in Figure 6 to form a first microwave heat generating region and a second microwave heat generating region, which was then dried at 90°C for 5 minutes and stored at 25°C for 24 hours to produce microwave heat generating film 1. The area of ​​the first microwave heat generating region (first area) was 60.0 mm 2 and the area of ​​the second microwave heating region (second area) is 6.0 mm 2 The distance between the first microwave heating region and the second microwave heating region (distance 4 in FIG. 6) was set to 2.0 mm.

[0090] For sealing, 300 g of water-soaked Kimtowel (manufactured by Nippon Paper Crecia Co., Ltd.) was placed in a PP container, and the container and microwave heat generating film 1 were heat-sealed under conditions of 180° C. for 1 second.

[0091] [Example 2] A microwave heating film 2 was produced in the same manner as in Example 1, except that the distance between the first microwave heating region and the second microwave heating region (distance 4 in FIG. 6) in the coating shape shown in FIG. 6 in Example 1 was changed to 5.0 mm. The area of ​​the first microwave heating region (first area) was 60.0 mm. 2 and the area of ​​the second microwave heating region (second area) is 6.0 mm 2 It was decided.

[0092] [Example 3] A microwave heat generating film 3 was produced in the same manner as in Example 1, except that the microwave heat generating composition 1 in Example 1 was changed to the microwave heat generating composition 2. The area of ​​the first microwave heat generating region (first area) was 60.0 mm 2 and the area of ​​the second microwave heating region (second area) is 6.0 mm 2 It was decided.

[0093] [Example 4] A microwave heat generating film 4 was produced in the same manner as in Example 1, except that the microwave heat generating composition 1 in Example 1 was changed to the microwave heat generating composition 3. The area of ​​the first microwave heat generating region (first area) was 60.0 mm 2 and the area of ​​the second microwave heating region (second area) is 6.0 mm 2 It was decided.

[0094] [Example 5] A microwave heating film 5 was produced by the same manufacturing method as in Example 1, except that the coating shape shown in Fig. 6 in Example 1 was changed to the coating shape shown in Fig. 7 and the distance between the first microwave heating region and the second microwave heating region (distance 4 in Fig. 7) was changed to 1.0 mm. The area of ​​the first microwave heating region (first area) was 60.0 mm. 2 and the area of ​​the second microwave heating region (second area) is 4.8 mm 2 It was decided.

[0095] [Example 6] A microwave heat generating film 6 was produced in the same manner as in Example 1, except that the coating shape shown in Fig. 6 in Example 1 was changed to the coating shape shown in Fig. 8. The area of ​​the first microwave heat generating region (first area) was 60.0 mm 2 and the area of ​​the second microwave heating region (second area) is 4.8 mm 2 It was decided.

[0096] [Example 7] A microwave heat generating film 7 was produced by the same manufacturing method as in Example 1, except that the distance between the first microwave heat generating region and the second microwave heat generating region in Example 1 (distance 4 in FIG. 6) was changed to 110 mm. The area of ​​the first microwave heat generating region (first area) was 60.0 mm. 2 and the area of ​​the second microwave heating region (second area) is 6.0 mm 2 It was decided.

[0097] [Comparative Example 1] A microwave heating film 8 was produced by the same manufacturing method as in Example 1, except that the coating shape shown in FIG. 6 in Example 1 was changed to the coating shape shown in FIG. 16 (i.e., the first microwave heating region was not provided). The area of ​​the second microwave heating region (second area) was 15.0 mm 2 It was decided.

[0098] [Comparative Example 2] A microwave heating film 9 was produced by the same manufacturing method as in Example 1, except that the coating shape shown in FIG. 6 in Example 1 was changed to the coating shape shown in FIG. 17 (i.e., the second microwave heating region was not provided). The area of ​​the first microwave heating region (first area) was 110.0 mm 2 It was decided.

[0099] [Comparative Example 3] A microwave heat generating film 10 was produced in the same manner as in Example 1, except that the microwave heat generating composition 1 in Example 1 was changed to silver ink (XA-4000, manufactured by Fujikura Kasei Co., Ltd.). The area of ​​the first microwave heat generating region (first area) was 60.0 mm 2 and the area of ​​the second microwave heating region (second area) is 6.0 mm 2 It was decided.

[0100] [Comparative Example 4] A microwave heat generating film 11 was produced in the same manner as in Example 1, except that the microwave heat generating composition 1 in Example 1 was changed to the microwave heat generating composition 4. The area of ​​the first microwave heat generating region (first area) was 60.0 mm 2 and the area of ​​the second microwave heating region (second area) is 6.0 mm 2 It was decided.

[0101] [Comparative Example 5] A microwave heating film 12 was produced by the same manufacturing method as in Example 1, except that the coating shape shown in Fig. 1 in Example 1 was changed to the coating shape shown in Fig. 18 (i.e., a solid coating was used without providing a second microwave heating region). The area of ​​the first microwave heating region (first area) was 640 mm 2 It was decided.

[0102] [Table 1]

[0103] <Evaluation> The microwave heating films of the Examples and Comparative Examples were evaluated for vapor permeability and controllability of the position of the vapor permeation holes.

[0104] [Vaporability] The heat-sealed container and film were heated in a microwave oven (RE-7500, manufactured by Sharp Corporation) at 500 W for 120 seconds and evaluated according to the following evaluation criteria. The results are shown in Table 2. (Evaluation Criteria) ○: 5mm 2 The above steam holes were formed. △: Steam holes were formed, but 5mm 2 It was less than. ×: Not steamed.

[0105] [Controllability of steam hole position] The heat-sealed container and film were heated in a microwave oven (RE-7500, manufactured by Sharp Corporation) at 500 W for 120 seconds and evaluated based on the following evaluation criteria. The results are shown in Table 2. In Table 2, "-" indicates that no steam was allowed to pass through. (Evaluation Criteria) ◯: Vaporization occurred only from the inside of the target region 5 in the first microwave heating region. △: Steam was generated from the inside and the periphery of the target area 5 in the first microwave heating region. ×: Steamed in patches.

[0106] Table 2 shows the evaluation results of the vapor permeability and the controllability of the vapor hole position of the microwave heating film.

[0107] [Table 2]

[0108] From Table 2, it was confirmed that, compared to Comparative Examples 1 to 5, Examples 1 to 7 have a means for generating heat by microwave irradiation that has high vapor permeability that allows vapor to pass even when the coating area of ​​the microwave heating region is small, and high controllability of the position of the vapor permeability holes.

[0109] The aspects of the embodiment of the present invention are as follows, for example. <1> at least one first microwave heating region having a first area; and one or more second microwave heating regions having a second area; The first area is larger than the second area in a plan view, The first microwave heating region and the second microwave heating region each have a surface resistivity of 5 Ω / □ to 10,000 Ω / □. A microwave heating film. <2> The second microwave heating region has a circular, elliptical, polygonal or corrugated shape in a plan view. <1> The microwave heating film according to claim 1. <3> The shortest distance between the first microwave heating region and the second microwave heating region is 100 mm or less at maximum. <1> from <2> 2. The microwave heating film according to claim 1 . <4> The second microwave heating region has a plurality of second microwave heating regions, the plurality of second microwave heating regions being located along the longitudinal direction of the first microwave heating region. <1> from <3> 2. The microwave heating film according to claim 1 . <5> The microwave heating device has a plurality of second microwave heating regions, the plurality of second microwave heating regions being located to the left and right of the first microwave heating region in a plan view. <1> from <3> 2. The microwave heating film according to claim 1 . <6> The above <1> from <5> 2. A microwave heating package comprising the microwave heating film according to claim 1. <7> forming at least one first microwave heating region having a first area on at least one of the substrates having a rectangular shape; forming one or more second microwave heating regions having a second area adjacent to the first microwave heating region; The first area is larger than the second area in a plan view, The first microwave heating region and the second microwave heating region each have a surface resistivity of 5Ω / □ to 10,000Ω / □. A method for producing a microwave heating film comprising the steps of: [Explanation of symbols]

[0110] 1 Microwave heating layer 2. First microwave heating region 3. Second microwave heating region 4. The shortest distance between the first microwave heating area and the second microwave heating area 5 Target area 11 Base material 12 Substrate with sealing properties 13. Sealant 100~104 Microwave heating film 200 Microwave heating packaging 201 Heat seal section 202 Container [Prior art documents] [Patent documents]

[0111] [Patent Document 1] Patent No. 6713797

Claims

1. at least one first microwave heating region having a first area; and one or more second microwave heating regions having a second area; The first area is larger than the second area in a plan view, The first microwave heating region and the second microwave heating region each have a surface resistivity of 5 Ω / □ to 10,000 Ω / □. A microwave heating film.

2. The microwave heating film according to claim 1 , wherein the second microwave heating region has a circular, elliptical, polygonal or corrugated shape in a plan view.

3. The microwave heating film according to claim 1 , wherein the shortest distance between the first microwave heating region and the second microwave heating region is a maximum of 100 mm or less.

4. The microwave heating film according to claim 1 , comprising a plurality of the second microwave heating regions, the plurality of second microwave heating regions being positioned along the longitudinal direction of the first microwave heating region.

5. The microwave heating film according to claim 1 , comprising a plurality of the second microwave heating regions, the plurality of second microwave heating regions being located to the left and right of the first microwave heating region in a plan view.

6. A microwave heating package comprising the microwave heating film according to claim 1.

7. forming at least one first microwave heating region having a first area on at least one of the substrates having a rectangular shape; forming one or more second microwave heating regions having a second area adjacent to the first microwave heating region; The first area is larger than the second area in a plan view, The first microwave heating region and the second microwave heating region each have a surface resistivity of 5 Ω / □ to 10,000 Ω / □. A method for producing a microwave heating film comprising the steps of:

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