JP2019172351A - Packaging base material and package for microwave treatment - Google Patents

Abstract

To provide a package for microwave treatment that ensures a ventilation part is formed in microwave treatment.SOLUTION: A package for microwave treatment 9 has an object that can be heated with microwaves, a container 5 having a recess 51 containing the object, and a sheet base material 2 that covers the recess 51 in a sealed manner. The sheet base material 2 is provided with an ink layer 3 that has the imaginary part of a complex dielectric constant at frequency 2.45GHz being 100 or more.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a packaging base material and a packaging body for microwave processing that can release vapor generated from an object during microwave processing to the outside.

2. Description of the Related Art Conventionally, a microwave processing package for heating an object (food, etc.) by performing microwave processing using a microwave oven or the like is known.
Among these, in the microwave processing package in which the object is packaged in a sealed manner, the internal pressure is excessively increased by the steam generated when the microwave processing is performed. Yes.
For example, in Patent Document 1, in a packaging container composed of a laminated film having a thermoplastic film layer and a thermoadhesive resin layer, nonmetallic microwave absorbent particles are placed in the nonmetallic resin on the inner surface of the thermoplastic film layer. A heating packaging container having a configuration in which a microwave absorbing layer made of dispersed ink is partially formed in a predetermined shape is disclosed.
As the microwave absorbing layer, an ink layer made of non-metallic microwave absorbing particles such as graphite, carbon black, zinc oxide and tin oxide and a binder resin is used.

JP 2001-139069 A

  However, even when an ink layer containing non-metallic microwave absorbing particles such as graphite is used as in Patent Document 1, there is a case where the ventilation portion cannot be formed during the microwave treatment.

  The objective of this invention is providing the packaging base material and the packaging body for microwave processing which can produce a ventilation | gas_flowing part reliably at the time of a microwave processing.

  According to studies by the present inventors, it has been found that even when an ink layer is formed using an ink containing carbon black, the temperature may not be sufficiently increased during the microwave treatment. Regarding this cause, various factors such as the type and content of carbon black, the type of additives such as a dispersant, and viscosity adjustment can be considered. Therefore, the present invention has been completed by paying attention to the dielectric properties of the ink layer.

  The packaging substrate of the present invention has a sheet substrate and an ink layer provided on the sheet substrate and having an imaginary part of a complex relative dielectric constant at a frequency of 2.45 GHz of 100 or more.

In a preferred packaging substrate of the present invention, the ink layer contains carbon black.
As for the preferable packaging base material of this invention, the said ink layer is comprised from the plate-shaped printing layer.
As for the preferable packaging base material of this invention, the said ink layer is comprised from the gravure printing layer.
A preferable packaging substrate of the present invention is a first ink layer in which the ink layer includes metal particles and an ink layer provided so as to surround the first ink layer, the ink layer being more than the first ink layer. A second ink layer having a large imaginary part of the complex relative dielectric constant.

According to another aspect of the present invention, a microwave processing package is provided.
The package for microwave processing according to the present invention includes an object that can be heated by microwaves, a container having a recess in which the object is placed, and a sheet base material that covers the recess in a sealed manner. An ink layer having an imaginary part of a complex relative dielectric constant of 100 or more at a frequency of 2.45 GHz is provided on the sheet base material.

  The packaging substrate and microwave treatment packaging body of the present invention can reliably generate a vent during microwave treatment.

The top view of the packaging base material of 1st Embodiment. The expanded sectional view cut | disconnected by II-II of FIG. The front view of the package for microwave processing of 1st Embodiment. The top view of the package body for the same microwave processing. The bottom view of the package for the same microwave processing. Sectional drawing cut | disconnected by VI-VI of FIG. The perspective view of a container. The perspective view of the package body which carried out the microwave process and in which the ventilation part was formed. Sectional drawing cut | disconnected by IX-IX of FIG. Sectional drawing of the package for microwave processing of the 1st modification of 1st Embodiment. The top view of the package for microwave processing of the 2nd modification. The top view of the package for microwave processing of the 3rd modification. The front view of the package for microwave processing of the 3rd modification. Sectional drawing cut | disconnected by XIV-XIV of FIG. The top view of the package for microwave processing of 2nd Embodiment. Sectional drawing cut | disconnected by XVI-XVI of FIG. The top view of the packaging base material of 3rd Embodiment. The expanded sectional view cut | disconnected by XVIII-XVIII of FIG. The front view of the package for microwave processing of 3rd Embodiment. The front view of the package for microwave processing of 4th Embodiment. Sectional drawing cut | disconnected by XXI-XXI of FIG. The front view when the package body is microwave-processed and the ventilation part is formed.

The present invention will be described below with reference to the drawings.
In the present specification, a numerical range represented by “lower limit value X to upper limit value Y” means a lower limit value X or more and an upper limit value Y or less. When a plurality of the numerical ranges are separately described, an arbitrary lower limit value and an arbitrary upper limit value can be selected, and “arbitrary lower limit value to arbitrary upper limit value” can be set.

[First Embodiment]
The packaging substrate of the present invention has a sheet substrate and an ink layer provided on the sheet substrate. The ink layer has an imaginary part having a complex dielectric constant of 100 or more.
Note that the imaginary part of the complex relative dielectric constant is generally sometimes referred to as dielectric loss.
In this specification, the imaginary part of the complex dielectric constant refers to a value obtained by measuring the ink layer at a frequency of 2.45 GHz under standard conditions (23 ° C., 1 atm, relative humidity 50%).
For details of the method for measuring the imaginary part of the complex dielectric constant, refer to the examples.

The packaging substrate of the present invention is appropriately processed so as to suit various uses in the packaging field.
For example, in the packaging substrate of the present invention, (a) an embodiment in which a packaging substrate and a container cooperate to coat an object that can be heated by microwaves in a sealed state, (b) the packaging substrate itself is micro It is used for a mode in which an article heated by a wave is covered in a sealed manner, (c) a mode in which an object that can be heated by a microwave is attached to a sealed container that is covered in a sealed state, and the like.
Hereinafter, an object that can be heated by microwaves is referred to as a “heating object”.

1st Embodiment is an aspect of said (a), Comprising: It is related with the packaging base material used as a shrink film which coat | covers the outer side of a container in the shape of a seal | sticker, and the package for microwave processing using the packaging base material.
FIG.1 and FIG.2 shows the packaging base material 1 of 1st Embodiment.
The packaging substrate 1 includes a sheet substrate 2 and an ink layer 3 provided on at least one surface of the sheet substrate 2. In the ink layer 3, the imaginary part of the complex relative dielectric constant at a frequency of 2.45 GHz is 100 or more. Preferably, the imaginary part of the complex relative dielectric constant at a frequency of 2.45 GHz of the ink layer 3 is 130 or more, more preferably 190 or more. Such an ink layer 3 can apply a sufficient heat to the sheet substrate to break it.
The sheet base material 2 has an extremely small imaginary part of the complex relative dielectric constant, and does not generate heat to the extent that the sheet base material 2 itself breaks during microwave processing.
The packaging substrate 1 of this embodiment seals the container as a whole from the outside of the container. Hereinafter, the sheet base material of such a packaging base material is particularly referred to as an “overlap sheet base material”. An ink layer having an imaginary part of the complex relative dielectric constant of 100 or more is referred to as a “specific ink layer”.
In each figure excluding the cross-sectional view, countless dots are added to the specific ink layer in order to make the specific ink layer easy to understand.

A heat-shrinkable film is used as the overlap sheet base material 21 constituting the packaging base material 1.
In this specification, a heat-shrinkable film refers to a film having a property (heat-shrinkable) that shrinks when heated to a predetermined temperature (for example, 70 ° C. to 100 ° C.).
In terms of materials, the heat-shrinkable film is not particularly limited as long as it has flexibility and heat-shrinkability and melts by heat. Polyolefin film; polyvinyl chloride film; polyethylene terephthalate film or polylactic acid Polyester film such as film (biodegradable film); Thermoplastic resin film such as polystyrene film; and the like, preferably polyolefin film.
In the polyolefin film, the main component resin constituting the film is a polyolefin resin. It does not specifically limit as a polyolefin-type film, For example, the polypropylene film comprised by polypropylene; The polyethylene film comprised by polyethylene etc. are mentioned, A polypropylene film is preferable. Examples of the polypropylene include a propylene homopolymer and a propylene-ethylene copolymer, and examples of the polyethylene include a polyethylene homopolymer and a polyethylene copolymer.
The heat-shrinkable film may be colorless and transparent, colored and transparent, or opaque. However, it is preferable to use a colorless and transparent film because the container can be clearly seen from the outside.

From the viewpoint of shrinkability, the heat-shrinkable film may be either a uniaxial shrink film that mainly heat shrinks in the first direction or a biaxial shrink film that mainly heat shrinks in the first direction and the second direction.
The first direction refers to one direction in the plane of the heat-shrinkable film, and the second direction refers to a direction orthogonal to the first direction in the plane of the heat-shrinkable film.

The heat shrinkage rate in the first direction of the uniaxial shrink film and the biaxial shrink film is, for example, 20% or more, preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. The heat shrinkage rate in the second direction of the uniaxially shrinkable film is, for example, 0 to 10%, preferably 0 to 5%. The heat shrinkage rate in the second direction of the biaxially shrinkable film is, for example, 10% or more, preferably 20% or more, more preferably 30% or more.
However, in this specification, the heat shrinkage rate is the film length before heating (stored in a 23 ° C. atmosphere for 24 hours) (original length) and the film after being immersed in 90 ° C. warm water for 10 seconds. It is obtained by substituting the length (the length after immersion) into the following formula. The length of each film is measured under standard conditions.
Thermal contraction rate (%) = [{(original length in the first direction (or second direction)) − ((length after immersion in the first direction (or second direction))} / ((first Original length of direction (or second direction)]] × 100.
The thickness of the overlap sheet | seat base material 21 is not specifically limited, For example, they are 8 micrometers-80 micrometers, Preferably, they are 10 micrometers-60 micrometers, More preferably, they are 12 micrometers-40 micrometers. If the thickness of the overlap sheet substrate 21 is too small, the strength is insufficient, and if it is too large, there is a possibility that a ventilation portion will not be generated in the overlap sheet substrate 21 due to heat generation of the specific ink layer 3 during microwave processing.

  As illustrated in FIG. 1, the overlap sheet base material 21 is formed in a long band shape, for example. The elongate belt shape refers to a substantially rectangular shape in plan view in which the length in one direction is sufficiently longer than the other direction. Although not particularly illustrated, the overlap sheet base material 21 may be formed in a substantially rectangular shape in plan view or a substantially square shape in plan view with a small difference in aspect ratio.

A specific ink layer 3 is provided on a part of the overlap sheet base material 21. In this specification, an ink layer is comprised from the ink solidified material which the ink solidified.
The specific ink layer 3 may be provided at one place of the overlap sheet base material 21 or may be provided dispersedly at several places.
The specific ink layer 3 is provided at a predetermined position of the overlap sheet substrate 21 in consideration of disposing the specific ink layer 3 corresponding to the predetermined position of the container as will be described later. In addition, since the overlap sheet | seat base material 21 of the example of illustration is made into a elongate strip shape so that a container can be continuously packaged (because it is made into a elongate strip shape so that the package for microwave processing can be manufactured continuously). A plurality of specific ink layers 3 are formed at regular intervals in the longitudinal direction.
The specific ink layer 3 is provided on the outer surface or the inner surface of the overlap sheet substrate 21 or on the outer surface and the inner surface, respectively. In the illustrated example, the specific ink layer 3 is provided on the outer surface of the overlap sheet base material 21.

The plan view shape of the specific ink layer 3 is not particularly limited, and may be a substantially rectangular shape in plan view as shown in the drawing. In addition, although not shown, a substantially square shape, a substantially circular shape, a substantially elliptical shape, a substantially triangular shape, It may be a substantially polygonal shape such as a substantially hexagonal shape.
In the present specification, “abbreviation” means a range allowed in the technical field to which the present invention belongs.
The specific ink layer 3 is provided in a solid shape. The solid ink layer means that the ink extends in the surface direction to form one continuous layer. However, since the layer formed by the plate printing method such as the gravure printing method is composed of a set of ink solidified substances adhering to dots, the ink solidified substance extends in the surface direction when viewed macroscopically. Note that there is an infinite number of fine gaps in the plane when viewed microscopically. Thus, when viewed microscopically, even if there is a fine gap, if it forms one continuous layer macroscopically, it is included in the solid category.
The area of one specific ink layer 3 is not particularly limited, but if it is too small, there is a possibility that a good ventilation portion cannot be formed at the time of microwave treatment. Therefore, it is preferably 0.25 square cm or more, and 1.0 square cm or more. Is more preferable.
The thickness of the specific ink layer 3 is not particularly limited, and is, for example, 0.3 μm to 20 μm, preferably 0.4 μm to 10 μm, and more preferably 0.5 μm to 5 μm. If the specific ink layer 3 is in the thickness range, the overlap sheet base material 21 on which the specific ink layer 3 is formed on the outer surface, the inner surface, or both surfaces can be beautifully wound into a roll. In general, since the overlap sheet base material 21 is often traded in a roll shape, the overlap sheet base material 21 having the specific ink layer 3 having the above thickness range is convenient for commercial transactions.

The components of the specific ink layer 3 are not particularly limited on the condition that the imaginary part of the complex relative dielectric constant has a dielectric characteristic of 100 or more.
The ink for forming the specific ink layer 3 is not particularly limited as long as it can form an ink layer having a frequency of 2.45 GHz and an imaginary part having a complex relative dielectric constant of 100 or more.

The ink that forms the specific ink layer 3 includes at least a microwave absorbent and a binder resin, and may include a colorant, a solvent, and an additive as necessary.
The microwave absorbent is not particularly limited, and examples thereof include carbon black, graphite, aluminum paste, zinc oxide, tin oxide, and iron oxide.
When the binder resin is classified according to solidification performance, examples thereof include a photopolymerization type such as a dry type and an ultraviolet curable type. Examples of the dry binder resin include acrylic resins, urethane resins, cellulose resins such as nitrocellulose and cellulose / acetate / butyrate, vinyl chloride resins, vinyl acetate resins, and polyester resins. Examples of the photopolymerizable binder resin include acrylate-based photopolymerizable resins and polymerization initiators. Examples of the solvent include esters such as ethyl acetate, propyl acetate, and butyl acetate; alcohols such as methanol, ethanol, isopropyl alcohol, and butanol; ketones such as acetone and methyl ethyl ketone; hydrocarbons such as toluene; water; Or a mixed solvent thereof. Examples of the colorant include known pigments or dyes. Examples of the additive include a dispersant, a plasticizer, an antisettling agent, an antioxidant, an ultraviolet absorber, and a flame retardant.
For example, the microwave absorbent is blended in an amount of 5 to 30 parts by weight with respect to 100 parts by weight of the binder resin.

The specific ink layer 3 can be formed by applying the ink to a part of the overlap sheet base material 21 and solidifying it.
The coating method is not particularly limited, and examples thereof include a plate printing method, a plateless printing method such as inkjet printing, and a coating method using a coater.
The plate printing method is different from a printing method that does not use a plate such as inkjet printing, and refers to a printing format using a printing plate, and includes an intaglio printing method, a relief printing method, a stencil printing method, a lithographic printing method, and the like. . The intaglio printing method typically includes gravure printing, the relief printing method typically includes flexographic printing and relief printing, and the stencil printing method typically includes silk. Screen printing is exemplified, and a typical example of the lithographic printing method is an offset printing method.
Since the specific ink layer 3 having a predetermined thickness can be formed, the specific ink layer 3 is preferably a plate printing layer formed by a plate printing method. In particular, the specific ink layer 3 is preferably a gravure printing layer formed by a gravure printing method because the width of the ink transfer amount can be designed widely and the specific ink layer 3 having a predetermined thickness can be easily formed.
Both the plate-shaped printing layer and the gravure printing layer are formed by a collection of dot-like ink solidified products, and the adhesion state of the ink solidified materials is slightly different depending on the printing format.
The specific ink layer 3 may be formed by one-time application of ink, or may be formed by repeatedly applying ink two or more times. The specific ink layer 3 is preferably an ink layer formed by 1 to 20 times of ink, more preferably 1 to 10 times, more preferably 1 to 5 times, and ink formed by 1 to 3 times. A layer is particularly preferred. The specific ink layer 3 having a multilayer structure by overcoating may be formed by overcoating of one kind of ink, or may be formed by overcoating of two or more kinds of ink.

Further, the overlap sheet base material 21 may be provided with an ink layer (not shown) other than the specific ink layer 3. Hereinafter, ink layers other than the specific ink layer 3 are referred to as “other ink layers”.
The other ink layer is provided at a desired location of the overlap sheet substrate 21 as needed by applying a conventionally known colored ink or transparent ink (medium ink).
When providing another ink layer, the other ink layer may be provided so as not to overlap the specific ink layer 3, or may be provided so that a part or all of the other ink layer overlaps the specific ink layer 3.
The thickness of the other ink layer is, for example, 0.5 μm to 10 μm, preferably 1 μm to 5 μm.

Next, FIG. 3 thru | or FIG. 6 shows the package for microwave processing of 1st Embodiment.
A package 9 for microwave processing includes a heating object 4, a container 5 having a recess 51 in which the object is placed, and a sheet base material 2 (overlap sheet base material 21) that covers the recess 51 in a sealed manner. And the specific ink layer 3 is provided on the sheet base material 2.

The heating object 4 is not particularly limited as long as it generates steam while being heated by microwaves in a microwave oven. Typically, the heating object 4 includes food, but may be non-food.
The food is not particularly limited, and examples thereof include solid food, semi-solid food, and liquid food. Examples of solid foods include cooked rice, meats, breads, and frozen products. Examples of semi-solid foods include gratin and curry. Examples of liquid foods include soup and tea. In the present embodiment in which no lid is used, the heating object 4 is preferably a solid food or a semi-solid food.

Referring to FIG. 7 as well, the container 5 includes a recess 51 having a storage space for storing the heating object 4, and a flange portion 52 projecting radially outward from the periphery of the upper end of the recess 51.
The concave portion 51 includes a bottom wall surface portion 511 and a cylindrical side wall surface portion 512 raised upward from the periphery of the bottom wall surface portion 511. The upper portion of the concave portion 51 (side wall surface portion 512) is an upper surface opening portion. It is said that. The side wall surface portion 512 may have a straight body shape, but in the illustrated example, the side wall surface portion 512 is formed in a mortar shape having an inner diameter that increases upward. The flange portion 52 extends outward from the upper end of the side wall surface portion 512.
Note that the imaginary part of the complex relative dielectric constant of the container 5 is extremely small, and the container 5 itself does not generate heat so as to melt and generate a vent during microwave processing.
The container 5 is formed from a material having heat resistance that does not spark and does not melt during microwave processing. The material of the container 5 is not particularly limited, and representative examples include foamed resin, non-foamed resin, glass, and ceramics. The resin container 5 is preferable because it is relatively inexpensive.
Examples of the resin container 5 include a sheet molded product, an injection molded product, and a blow molded product.

In the microwave processing package 9 of the present embodiment, the packaging substrate 1 having the overlap sheet substrate 21 is heat-sealed and mounted in a sealed manner outside the container 5 in which the object to be heated 4 is accommodated in the recess 51. ing.
The overlap sheet base material 21 is in close contact with the outer surface of the bottom wall surface portion 511 of the container 5 and the upper surface of the flange portion 52, but between the protruding end 52 a of the flange portion 52 and the periphery of the bottom wall surface portion 511. Is separated from the outer surface of the side wall surface portion 512 of the container 5.
The arrangement of the specific ink layer 3 with respect to the container 5 is not particularly limited. For example, the specific ink layer 3 may be disposed at a position corresponding to the upper surface opening of the container 5, may be disposed at a position corresponding to the flange portion 52 of the container 5, and the side wall surface portion 512 of the container 5. It may be arranged at a position corresponding to.
Preferably, it is preferably disposed at a position having a space between the container 5 and the position corresponding to the upper surface opening of the container 5 or the side wall surface 512 of the container 5. The position to do is mentioned.
In the illustrated example, the specific ink layer 3 is disposed at a position corresponding to the side wall surface portion 512 of the container 5. Part of the specific ink layer 3 may be disposed at a position corresponding to the side wall surface portion 512 of the container 5, or all of the specific ink layer 3 may be disposed at a position corresponding to the side wall surface portion 512 of the container 5. .
In the illustrated example, the entire specific ink layer 3 is not overlapped with the flange portion 52 and the bottom wall surface portion 511 but is disposed at a position corresponding to the side wall surface portion 512. Preferably, the specific ink layer 3 is disposed so that the upper end of the specific ink layer 3 is positioned below the protruding end 52a of the flange portion 52, and more preferably, the protruding end 52a of the flange portion 52 and the side wall portion 512 The specific ink layer 3 is disposed so as to be located in a region between the height direction intermediate points.
Further, the specific ink layer 3 is formed in a substantially rectangular shape or a horizontally long trapezoidal shape in a plan view, and corresponds to the side wall surface portion 512 so that its long axis extends along the circumferential direction of the side wall surface portion 512 of the container 5. It is arranged at the position to do.

The microwave processing package 9 can be obtained, for example, as follows.
As shown in FIG. 1, the container 5 is wrapped while aligning the long belt-like overlap sheet base material 21 so that the specific ink layer 3 corresponds to a predetermined portion (for example, the side wall surface portion 512) of the container 5, By overlapping and heat-sealing inner surfaces of both end portions along the longitudinal direction, a heat-sealing portion extending in the longitudinal direction is formed, and an overlap sheet base material 21 formed in a cylindrical shape while wrapping the container 5 is formed. Is formed into a sealed bag shape by performing a heat insulation seal in the lateral direction at both front and rear end portions of the container 5. Thereafter, the overlap sheet substrate 21 formed in the sealed bag shape is heated and thermally contracted, whereby the container 5 having the recess 51 containing the heating object 4 as shown in FIGS. 3 to 6 is overlapped. The microwave processing package 9 packaged hermetically with the base material 21 is obtained. 3 to 6, the symbol X indicates a heat seal portion in the longitudinal direction, and Y indicates a heat seal portion in the short direction.
In addition, the package 9 for microwave processing can also be produced using the overlap sheet | seat base material 21 which does not have a specific ink layer. Specifically, after using the overlap sheet base material 21 not provided with a specific ink layer, in the same manner as in the above production method, after obtaining a storage sealed body packaged in a sealed manner with the overlap sheet base material 21 Then, by applying ink at a predetermined position on the outer surface of the overlap sheet base material 21 after heat shrinkage to form the specific ink layer 3, the package 9 for microwave processing as shown in FIGS. Is obtained.

The package 9 for microwave processing is used for microwave processing using a household or commercial microwave oven.
When the microwave treatment is performed, steam is generated from the heating object 4, the internal pressure gradually increases, and the specific ink layer 3 generates heat. While the packaging substrate 1 is pushed outward by the increase in internal pressure, the overlap sheet substrate 21 in the region where the specific ink layer 3 overlaps or the peripheral edge region of the specific ink layer 3 is weakened by the heat generation of the specific ink layer 3 or By overlapping, the overlap sheet base material 21 is partially broken. When the overlap sheet base material 21 is partially broken, as shown in FIGS. 8 and 9, a ventilation portion 6 is generated in the surface of the packaging base material 1, and steam is discharged to the outside of the packaging body.
Since the packaging base material 1 of the present invention is provided with an ink layer having an imaginary part of complex relative dielectric constant of 100 or more, the air-permeable part 6 can be reliably generated in the sheet base material 2 during the microwave treatment. .
In the present invention, when selecting an ink layer that can surely break the sheet base material 2 and form the ventilation portion 6 during the microwave treatment, an element that the imaginary part of the complex dielectric constant at a frequency of 2.45 GHz is 100 or more is used as an index. It can also be said that this is what provided.

In particular, since the specific ink layer 3 is provided at a position having a space between the container 5 and the heat, the heat generated from the specific ink layer 3 is not easily absorbed by the container 5 and acts quickly on the overlap sheet substrate 21. It becomes like this.
Further, since the specific ink layer 3 is disposed below the protruding end 52a of the flange portion 52, the overlap sheet base material 21 that is tensioned by heat shrinkage has a large size as shown in FIGS. The ventilation part 6 is generated, and the upper film edge defining the ventilation part 6 reaches the upper opening part beyond the protruding end 52a of the flange part 52. For this reason, it becomes easy to discharge | evaporate the vapor | steam which arises from the heating target object 4 outside, and after removing a small amount of microwave processing, the packaging base material 1 can be easily removed from the film edge using the ventilation | gas_flowing part 6. FIG. it can.

<Modification of First Embodiment>
In the microwave processing package 9 of the first embodiment, the upper opening of the recess 51 in which the object to be heated 4 is placed is opened, and the packaging substrate 1 is mounted so as to cover the upper opening. However, for example, as shown in FIG. 10, the packaging substrate 1 may be heat-shrink mounted on the container 5 provided with the lid member 53.
Specifically, the microwave processing package 9 of the first modified example includes the heating object 4, the recess 51 in which the heating object 4 is placed, and the flange portion 52 protruding from the recess 51. The container 5, the lid 53 that closes the upper opening of the recess 51 of the container 5, the overlap sheet base 21 that is heat-shrinkably attached to the outside of the container 5 including the lid 53, and the overlap sheet And a packaging substrate 1 having a specific ink layer 3 provided on the substrate 21. The lid 53 may be detachably bonded to the container 5 by means such as heat sealing, or may be detachably fitted to the container 5.
In the lid member 53 bonded to the container 5, the steam generated from the heating object 4 during the microwave treatment is discharged to the outside of the lid member 53. It is provided with a known steaming means such as being weakly bonded so as to be peeled off, or having a separate steaming mechanism that partially creates a vent hole in the lid member 53. In the lid member 53 fitted in the container 5, the steam is discharged from the gap between the lid member 53 and the container 5 to the outside of the lid member 53.
Similarly, since the specific ink layer 3 is provided in the microwave treatment packaging body 9 of the first modification, the ventilation portion 6 is formed in the packaging substrate 1 during the microwave treatment, and the outside of the lid 53 is formed. The discharged steam is discharged from the vent 6 to the outside of the package.

In addition, the microwave processing package 9 of the first embodiment uses a substantially circular container 5 in a plan view. For example, as shown in FIG. The one to which the packaging substrate 1 is attached may be used. In addition, containers 5 having a substantially polygonal shape such as a substantially elliptical shape in plan view and a substantially hexagonal shape in plan view may be used.
Moreover, although the flange part 52 of the container 5 of the first embodiment has a flat upper end surface (in other words, the flange part 52 is linear in a front view), FIG. 12 to FIG. As shown in FIG. 4, the upper end surface of the flange portion 52 may be formed in a non-flat shape having a height difference. 12 to 14, the container 5 is formed in a substantially elliptical shape in plan view, and the short-axis-side flange portion 521 of the ellipse protrudes upward from the long-axis-side flange portion 522.

  Hereinafter, although another embodiment of the present invention will be described, in the description, the configuration and effects different from those of the above-described embodiment will be mainly described. For the same configuration and the like, terms or symbols are used as they are, The description of the configuration may be omitted.

[Second Embodiment]
2nd Embodiment is an aspect of said (b), Comprising: It is related with the packaging base material used as a packaging film which coat | covers a heating target object in a sealing form, and the package for microwave processing using the packaging base material.
The packaging substrate 1 of the present embodiment also seals the object to be heated 4 as a whole as in the first embodiment, and the overlap sheet substrate 21 is used. 21 differs from the said 1st Embodiment by the point comprised by the film which does not have heat shrinkability substantially.
The packaging substrate 1 of the present embodiment is the same as that described in the first embodiment except that a film that does not substantially heat shrink is used as the overlap sheet substrate 21. It is.
A film having substantially no heat shrinkability (hereinafter referred to as a non-heat shrinkable film) includes a film having a heat shrinkage rate of 10% or less in the first direction and the second direction, preferably 5% or less. is there.
As the non-heat-shrinkable film, the thermoplastic resin film as described above is used from the viewpoint of material, and a polyolefin-based film is preferably used.

As shown in FIGS. 15 and 16, the microwave processing package 9 of the present embodiment includes a heating object 4, an overlap sheet base material 21 that covers the object to be sealed, and an overlap sheet base material 21. And a specific ink layer 3 provided on the surface.
Such a microwave processing package 9 is formed by wrapping the overlap sheet substrate 21 on the inner surfaces of both end portions so as to wrap the heating object 4 in the overlap sheet substrate 21 on which the specific ink layer 3 is formed. By overlapping and heat-sealing each other, a heat seal portion extending in the longitudinal direction is formed, and the overlap sheet base material 21 formed in a cylindrical shape is short-sided at both front and rear end portions of the heating object 4. It is obtained by sealing with melt insulation.
Note that the specific ink layer 3 may be formed on the overlap sheet substrate 21 after the heating object 4 is packaged in a sealed bag shape with the overlap sheet substrate 21 having no specific ink layer.
Similarly to the first embodiment, the microwave processing package 9 of the present embodiment can also reliably generate the ventilation portion 6 in the sheet base material 2 during the microwave processing.

[Third Embodiment]
The third embodiment is the above-described aspect (c), and is a packaging substrate used by being attached to a hermetic container in which the object to be heated is covered in a hermetically sealed manner, and a microwave processing packaging using the packaging substrate. About the body.
FIG.17 and FIG.18 shows the packaging base material 1 of 3rd Embodiment.
The packaging substrate 1 has a sheet substrate 2 and a specific ink layer 3. The sheet base material 2 is preferably formed with another ink layer 71 displaying a pattern or a design.
The packaging substrate 1 of this embodiment is used by being attached to a hermetic housing. Hereinafter, the sheet substrate of the packaging substrate 1 having such an aspect is particularly referred to as a “label sheet substrate”.

The planar view shape of the label sheet base material 22 is not particularly limited, and may be a substantially rectangular shape as illustrated, a substantially circular shape, a substantially elliptical shape, a substantially polygonal shape such as a substantially triangular shape or a substantially hexagonal shape, or a substantially star shape. Any other shape may be used.
The material of the label sheet base material 22 is not particularly limited, and examples thereof include a synthetic resin film, paper, nonwoven fabric, and synthetic paper. Preferably, a synthetic resin film is used.
Examples of the synthetic resin film include thermoplastic resin films such as ester films such as polyethylene terephthalate and polylactic acid, polyolefin films such as polypropylene, and styrene films such as a styrene-butadiene copolymer.
The thickness of the label sheet base material 22 is not specifically limited, For example, it is 25 micrometers-100 micrometers, Preferably it is 30 micrometers-60 micrometers.
Although the label sheet base material 22 may have heat shrinkability, it is preferable to use a material that does not substantially have heat shrinkability.
The specific ink layer 3 is provided on the outer surface or the inner surface of the label sheet substrate 22, or on the outer surface and the inner surface, and preferably, the specific ink layer 3 and the other ink layer 71 are provided.
In the illustrated example, the specific ink layer 3 and the other ink layer 71 are provided on the outer surface of the label sheet base material 22. The specific ink layer 3 and the other ink layer 71 may be provided so that at least a part thereof overlaps. However, in the illustrated example, the specific ink layer 3 and the other ink layer 71 are arranged side by side without overlapping each other. .
An adhesive layer 72 is provided on the inner surface of the label sheet substrate 22. The adhesive layer 72 is formed of a known pressure-sensitive adhesive or adhesive, and is preferably formed from a pressure-sensitive adhesive.
The thickness of the adhesive layer 72 is not particularly limited, but if it is too thick, the heat of the specific ink layer 3 is difficult to be transmitted, and is preferably 10 μm to 30 μm, and more preferably 10 μm to 20 μm.

FIG. 19 shows a microwave processing packaging body in which the packaging substrate of this embodiment is attached to a hermetic housing.
The sealed container of the present embodiment is the same as the microwave processing package of the first or second embodiment (however, the specific ink layer is not formed on the overlap base material).
This sealed container is a container 5 (or a heating object 4) in which a heating object 4 is placed and is packaged in a sealed manner with an overlap sheet base material 21.
By attaching the packaging substrate 1 of the present embodiment to an arbitrary portion of the overlap sheet substrate 21, the packaging body 9 for microwave processing is obtained.
In the packaging base material 1 in which the adhesive layer 72 is provided on the label sheet base material 22, the label sheet base material 22 can be attached to any position via the adhesive material layer 72.
Also in the microwave processing package 9 of the present embodiment, the specific ink layer 3 generates heat during the microwave processing, and the aeration part 6 is generated in the overlap sheet base material 21 by the heat.

[Fourth Embodiment]
Moreover, the specific ink layer 3 may be comprised from 2 or more types of ink layers adjacent to the surface direction.
In this case, the two or more ink layers may have the same imaginary part of the complex dielectric constant, but the imaginary part is preferably different.

Specifically, as shown in FIGS. 20 and 21, the specific ink layer 3 includes two or more ink layers 31 arranged adjacent to each other in the surface direction of the overlap sheet base material 21 (sheet base material 2). , 32. It is preferable that at least one of the ink layers 31 and 32 arranged adjacent to each other is an ink layer having an imaginary part having a complex relative dielectric constant of 100 or more, and both the ink layers 31 and 32 are both complex dielectric constants. It is more preferable that the imaginary part of the rate is an ink layer of 100 or more.
In the illustrated example, a case where two ink layers are arranged in parallel is illustrated. Hereinafter, they are referred to as a first ink layer 31 and a second ink layer 32. 20 and 22, the first ink layer is shaded and the second ink layer is numbered with dots.
The imaginary part of the complex relative dielectric constant of the first ink layer 31 is smaller than the imaginary part of the complex dielectric constant of the second ink layer 32.
Preferably, the first ink layer 31 is an ink layer containing metal particles and having an imaginary part of a complex relative dielectric constant of 100 or more, and the second ink layer 32 is more complex relative dielectric constant than the first ink layer 31. The ink layer has a large imaginary part.

  The first ink layer 31 and the second ink layer 32 may be arranged adjacent to each other in the surface direction, having a portion that overlaps with each other in the thickness direction, or a portion that overlaps each other in the thickness direction. And may be arranged adjacent to each other in the surface direction, or may be arranged adjacent to each other in the surface direction without overlapping each other as illustrated. The term “adjacent” refers to a state in which the edge of the first ink layer 31 and the edge of the second ink layer 32 are in contact with each other, or only from the first ink layer 31 while the first ink layer 31 and the second ink layer 32 overlap. The edge of the portion and the edge of the second ink layer 32 are adjacent to each other, or only from the edge of the first ink layer 31 and the second ink layer 32 while the first ink layer 31 and the second ink layer 32 overlap. The state where the edges of the parts are next to each other.

The first ink layer 31 and the second ink layer 32 may be disposed adjacent to each other so that one does not surround the other in plan view, and as illustrated, one is disposed adjacent to each other so as to surround the other. It may be. Preferably, the second ink layer 32 is provided so as to surround the first ink layer 31.
Specifically, for example, the second ink layer 32 is provided around the first ink layer 31 having a substantially band shape in a plan view so as to form a ring shape in a plan view. The first ink layer 31 and the second ink layer 32 are each directly fixed to the overlap base material 21. The peripheral edge of the first ink layer 31 is in contact with the inner edge of the second ink layer 32. In the illustrated example, the peripheral edge of the first ink layer 31 and the inner edge of the second ink layer 32 are shown in close contact with each other, but it is difficult to form two ink layers with such accuracy. Therefore, in practice, there is a portion where the peripheral edge of the first ink layer 31 and the inner edge of the second ink layer 32 are slightly separated, or the peripheral edge portion of the first ink layer 31 and the inner edge of the second ink layer 32. It should be noted that there are places where the parts slightly overlap.

Examples of the ink that forms the first ink layer 31 include ink containing metal particles such as aluminum. The ink that forms the second ink layer 32 is an ink that contains non-metallic particles such as carbon black and graphite, and has a larger imaginary part of the complex relative dielectric constant than the ink that forms the first ink layer 31. Can be mentioned.
The difference between the imaginary part of the complex dielectric constant of the second ink 32 and the first ink layer 31 (the imaginary part of the complex dielectric constant of the second ink layer 32−the imaginary part of the complex dielectric constant of the first ink layer 31) is , More than 0, preferably 100 or more, more preferably 130 or more, and still more preferably 190 or more.

  As in the present embodiment, the specific ink layer 3 is provided so as to surround the first ink layer 31 containing metal particles, and the first ink layer 31, and is an imaginary number having a complex relative dielectric constant than the first ink layer 31. When the second ink layer 32 having a large portion is included, the sheet base material 2 is broken at or near the boundary between the first ink layer 31 and the second ink layer 32 when irradiated with microwaves. (See FIG. 22). This is because the free electrons of the metal contained in the first ink layer 31 move greatly by the microwave, and the heat generation of the second ink layer 32 having a large imaginary part of the complex relative dielectric constant is promoted. This is because the sheet substrate 2 is considered to break. By using the specific ink layer 3 having the first ink layer 31 and the second ink layer 32 adjacent to each other as described above, it is possible to control a location where the sheet base material 2 such as the overlap base material 21 is broken.

In addition, in this embodiment, the case where the specific ink layer 3 comprised from the 2 or more types of ink layer arranged in parallel by the surface direction was applied to the overlap base material 21 of the said 1st Embodiment was illustrated. However, the present invention is not limited to this, and may be applied to the sheet base materials of the second and third embodiments.
In addition, two or more configurations selected from the various embodiments described above may be appropriately combined, or one or more configurations selected from the various embodiments described above may be replaced with other embodiments. May be.

  EXAMPLES Hereinafter, the Example and comparative example of this invention are shown and this invention is explained in full detail. However, the present invention is not limited to the following examples.

[Example 1]
The black ink A obtained by adjusting a commercially available black ink by a known general-purpose method so as to be capable of gravure printing is applied to a polypropylene film (Kojin Polyset AS, manufactured by Kojin Film & Chemicals Co., Ltd.). An ink layer was formed by printing in a solid form using a printing machine. In addition, although the thickness of a film and the thickness of an ink layer are preset, when measuring the imaginary part of a complex relative dielectric constant, refer to the value measured correctly.
This polypropylene film was a biaxial shrink film, and the thermal shrinkage rate in the MD direction was about 16%, and the thermal shrinkage rate in the TD direction was about 20%. However, this thermal shrinkage rate is a value measured at 100 ° C. according to JIS Z 1709.
The ink layer was formed in a rectangular shape of length × width = 350 mm × 80 mm in plan view.
The film having an ink layer formed on a part thereof was used as an evaluation sample, and the imaginary part of the complex dielectric constant was measured according to the following method to evaluate the shrinkability described later.
The results are shown in Table 1.

[Measurement of imaginary part of complex relative permittivity]
Of the evaluation sample, the region where the ink layer is laminated is cut into a rectangle of length × width = 76 mm × 30 mm (this cut piece has an ink layer on the entire film), and the horizontal direction is the circumferential direction. And is set in a cylindrical cavity resonator of the following cavity resonator perturbation method dielectric constant measurement system, under standard conditions (23 ° C., 1 atm, relative humidity 50%) according to the following measurement method: The imaginary part ε _S of the complex relative dielectric constant of the evaluation sample was measured.

<System configuration>
Network analyzer: E8361A from Agilent
Cylindrical cavity resonator: CP481 manufactured by Kanto Electronics Application Development Co., Ltd.
Measurement frequency: 2.45 GHz
Measurement mode: TM020
Calculation program: CPMA-PNA
<Measurement conditions>
Sample width input value: 30 mm.
Sample thickness input value: measured sample thickness t _S
<Measurement of thickness>
Film thickness: spline micrometer SPM2-25MX manufactured by Mitutoyo Corporation
Ink layer thickness: 3D measurement laser microscope LEXT OLS4100 manufactured by Olympus Corporation. The measurement magnification was 2160 times, and the measurement visual field was 128 μm.

<Calculation of imaginary part of complex relative permittivity of ink layer>
From the obtained measured value ε _S , the imaginary part ε _A of the complex relative dielectric constant of the ink layer was calculated using Equation (1). In addition, the imaginary part ε _B of the complex relative dielectric constant of the film itself is obtained by measuring a polypropylene film having no ink layer as a blank with the above measurement system and measurement conditions.
ε _A = (t _S ε _S -t _B ε _B ) / t _A formula (1)
ε _A : Imaginary part of complex relative permittivity of ink layer ε _S : Imaginary part of complex relative permittivity of evaluation sample (measured value)
ε _B : Imaginary part of complex relative permittivity of film (measured value)
t _A : thickness of ink layer (μm)
t _S : Total thickness (μm) of the evaluation sample
t _B : film thickness (μm)

[Shrinkage evaluation]
A region of the evaluation sample where the ink layer is laminated is cut into a square of length × width = 50 mm × 50 mm so that the ink layer of the evaluation sample is substantially in the center, and this is cut into a commercially available microwave oven (frequency 2 .45 GHz, rated high-frequency output of 500 W) using a thread and suspended in a hollow state and irradiated with microwaves for a maximum of 2 minutes.
The state was observed and the time was measured, and the presence or absence of shrinkage, the degree of shrinkage when shrinking, and the elapsed time (how many seconds after microwave irradiation) were evaluated. The evaluation criteria were as follows.
A: Shrinkage deformation occurred so that the original shape of the square film could not be recognized within 10 seconds after the microwave irradiation.
◯: More than 10 seconds after microwave irradiation, the film was contracted and deformed so that the original shape of the square film could not be recognized.
X: It did not shrink.

[Examples 2 to 4 and Comparative Examples 1 and 2]
An evaluation sample having each ink layer was prepared in the same manner as in Example 1 except that the black ink A of Example 1 was changed to inks B to F shown in Table 1, respectively. The imaginary part of the rate was measured and the shrinkage was evaluated. The results are shown in Table 1.

As shown in the results of Table 1, in Examples 1 to 4 in which the imaginary part ε _A of the complex relative dielectric constant has an ink layer of 100 or more, the film was thermally contracted by microwave irradiation, whereas the complex In Comparative Examples 1 and 2 having an ink layer having an imaginary part of relative permittivity of less than 100, the film did not thermally shrink even when irradiated with microwaves for 2 minutes. In particular, Examples 1 to 3 having an ink layer having an imaginary part ε _A having a complex relative dielectric constant exceeding 150 thermally contracted in a very short time. Therefore, it can be seen that an ink layer (that is, a specific ink layer) having an imaginary part of a complex relative dielectric constant of 100 or more (preferably 150 or more) generates a large amount of heat due to microwaves.

[Example 5]
An evaluation sample having an ink layer of black ink C was prepared in the same manner as in Example 3 except that the polypropylene film of Example 3 was changed to a polyethylene terephthalate film (LX18S manufactured by Mitsubishi Chemical Corporation).
The polyethylene terephthalate film was a uniaxial shrink film, and the heat shrinkage rate in the main heat shrink direction was about 69%. However, this heat shrinkage ratio is the length (original length) of the sheet base material before heating (stored for 24 hours under standard conditions) and the sheet base material after being immersed in 90 ° C. warm water for 10 seconds. The length (length after immersion) was measured and substituted into the above formula.

For the evaluation sample of Example 5, the imaginary part of the complex relative dielectric constant was measured in the same manner as described above, and the contractility was evaluated. The results are shown in Table 2.
However, in the measurement of the imaginary part of the complex relative dielectric constant of Example 5, since the region in which the ink layer was laminated in the evaluation sample was cut into a rectangle of length × width = 76 mm × 5 mm, < The sample width input value of measurement condition> was set to 5 mm.

[Comparative Examples 3 to 5]
An evaluation sample having each ink layer was prepared in the same manner as in Example 5 except that the black ink C of Example 5 was changed to the inks G to I shown in Table 2, respectively. The imaginary part of the rate was measured and the shrinkage was evaluated. The results are shown in Table 2.

[Examples 6 to 8]
An evaluation sample having each ink layer was prepared in the same manner as in Example 5 except that inks G to I shown in Table 2 (inks used in Comparative Examples 3 to 5) were overcoated on the black ink C. In the same manner, the imaginary part of the complex relative dielectric constant was measured and the shrinkage was evaluated. The results are shown in Table 2.
In addition, <calculation of the imaginary part of the complex relative dielectric constant of the ink layer> in the case of overcoating was performed using the following formula (2).
ε _A == (t _S ε _S -t _B ε _B -t _C ε _C ) / t _A formula (2)
ε _A : Imaginary part of complex relative permittivity of ink layer (black ink layer C) to be evaluated ε _S : Imaginary part of measured complex relative permittivity (measured value)
ε _B : Imaginary part of complex relative permittivity of polyethylene terephthalate film (measured value)
ε _C : Imaginary part of complex relative permittivity of overcoat ink layer (blue ink layer G, red ink layer H, yellow ink layer I) t _A : thickness of ink layer (black ink layer C) to be evaluated (μm) )
t _S : Total thickness (μm) of the evaluation sample
t _B : Polyethylene terephthalate film thickness (μm)
t _C : Thickness (μm) of overcoat ink layer (blue ink layer G, red ink layer H, yellow ink layer I)

  The ink layers of Examples 6 to 8 are two types and two layers of ink layers in which each of the ink layers of Comparative Examples 3 to 5 is laminated on the ink layer of Example 5. The imaginary part of the complex dielectric constant of each of the ink layers of Examples 6 to 8 is smaller than the imaginary part of Example 5, but both are 100 or more, and the shrinkability of the sample having the ink layer is also high. It was good. This means that if the imaginary part of the complex relative dielectric constant has an ink layer of 100 or more, even if an ink layer having an imaginary part of less than 100 is laminated, the exothermic property is not inhibited. ing. In addition, it can be seen that Comparative Examples 3 to 5 having an ink layer having an imaginary part of complex relative permittivity of less than 100 do not shrink even when irradiated with microwaves for 2 minutes and do not substantially generate heat.

[Example 9]
The black ink C used in Example 3 is printed in a solid shape on the polypropylene film of Example 1 using a gravure printing machine, thereby forming an ink layer having a length × width = 5 mm × 120 mm and a thickness of about 3 μm, A packaging substrate was prepared.
A commercially available resin container having a recess having a storage space having a substantially elliptical shape in plan view as shown in FIGS. 12 to 14 was prepared. Gratin is put into the recess as a heating object, and the periphery of the container is wrapped with the produced packaging base material (with the ink layer outside), and both side edges of the packaging base material are placed along the longitudinal direction of the container. The packaging base material was formed in a sealed bag shape by heat sealing by gluing and sealing in a transverse direction at both front and rear end portions of the container. Then, the packaging body as shown in FIG. 12 thru | or 14 was produced by heat-shrinking the packaging base material formed in the said sealing bag shape. In the package, the packaging substrate was mounted on the container so that the longitudinal direction of the ink layer extended along the circumferential direction of the side wall surface portion of the container, and the entire ink layer corresponded to the inside of the side wall surface portion.
When this package is heated in a commercially available microwave oven (frequency 2.45 GHz, rated high-frequency output 500 W) for 2 minutes, the film breaks at the ink layer, creating a vent, and the vapor is discharged to the outside. It was.

[Example 10]
The black ink A used in Example 1 is printed on the polypropylene film of Example 1 in a solid shape of length × width = 13 mm × 152 mm by using a gravure printing machine, so that a thickness of about 7 μm in a plan view is obtained. Two ink layers were formed. The first ink layer having a thickness of about 1 μm is obtained by performing gravure printing on a central portion of the second ink layer having the length × width = 13 mm × 152 mm and overlapping the silver ink in a plane view of length × width = 7 mm × 146 mm. Was formed on the second ink layer. In this way, a packaging substrate was produced.
This ink layer is a belt-shaped first ink layer (silver ink layer) of length × width = 7 mm × 146 mm, and a belt-shaped second ink layer (black ink layer) having a width of 3 mm around the ink layer as viewed in a plan view. The first ink layer overlaps the second ink layer existing on the back side thereof.
In addition, in order to measure the imaginary part of the complex dielectric constant of the silver ink used in Example 10, an evaluation sample was prepared in the same manner as in Example 1 using the silver ink, and the imaginary part was measured. The imaginary part of the complex dielectric constant was 15. Therefore, the difference between the imaginary part of the complex dielectric constant of the second ink layer (black ink layer A) and the imaginary part of the complex dielectric constant of the first ink layer (silver ink layer) is 245.5.

By mounting this packaging substrate on a container in the same manner as in Example 9, a package as shown in FIGS. 20 and 21 was produced.
When this package is heated in a commercially available microwave oven (frequency 2.45 GHz, rated high-frequency output 500 W) for 2 minutes, the film breaks at the ink layer, creating a vent, and the vapor is discharged to the outside. It was.

DESCRIPTION OF SYMBOLS 1 Packaging base material 2 Sheet | seat base material 3 Ink layer whose imaginary part of complex dielectric constant is 100 or more 4 Object 5 Container 51 Recessed part of container 52 Flange part of container 9 Packaging body for microwave processing

Claims (6)

  A packaging substrate comprising: a sheet substrate; and an ink layer provided on the sheet substrate and having an imaginary part of a complex relative dielectric constant at a frequency of 2.45 GHz of 100 or more.   The packaging substrate according to claim 1, wherein the ink layer contains carbon black.   The packaging substrate according to claim 1 or 2, wherein the ink layer is composed of a plate-shaped printing layer.   The packaging substrate according to any one of claims 1 to 3, wherein the ink layer is composed of a gravure printing layer.   The ink layer is a first ink layer containing metal particles and an ink layer provided so as to surround the first ink layer, and has an imaginary part having a complex relative dielectric constant larger than that of the first ink layer. The packaging substrate according to any one of claims 1 to 4, comprising a second ink layer. An object that can be heated by microwaves, a container having a recess in which the object is placed, and a sheet base material that covers the recess in a sealed manner,
A package for microwave processing, wherein the sheet base material is provided with an ink layer having an imaginary part of a complex relative dielectric constant at a frequency of 2.45 GHz of 100 or more.

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