JP2023153972A - Container with lid for microwave heating - Google Patents

Abstract

To provide a container with a lid for microwave heating capable of improving reliability with which a lid material is detached and passes steam.SOLUTION: A container with a lid for microwave heating comprises a paper-made container body having a flange at an opening and storing a content and a lid material for sealing the container body. A basis weight of paper of the container body is 150-400 g/m2, the lid material has a substrate layer and a sealant layer, and has a heat generation print layer at a part between the substrate layer and the sealant layer or at a part opposite to the sealant layer of the substrate layer. The container with the lid is sealed by a heat seal region by heat-sealing at least a part of the flange, and the sealant layer, and has the heat generation print layer in the following region 1B and region 2B when the container with the lid is seen in a plan view. A region 1B: A region leading to a part in a circumferential direction of an inner peripheral edge of the flange from a part in the circumferential direction of an outer peripheral edge of the heat seal region. A region 2B: A region which is in continuation with the region 1B and is situated inside of the inner peripheral edge of the flange.SELECTED DRAWING: Figure 6

Description

The present invention relates to a container with a lid for heating in a microwave oven.

2. Description of the Related Art There are commercially available sealed containers for heating in a microwave oven that can be heated in a microwave oven to cook food or the like while the contents are stored therein. When these sealed containers for heating in a microwave oven are heated in a microwave oven, the internal pressure inside the container increases, causing the container to deform or burst, so various proposals have been made to prevent this. (For example, Patent Document 1).

The packaging container of Patent Document 1 is provided with an inner seal part and an outer seal part, and a non-seal part is provided between the inner seal part and the outer seal part, and further, a part of the inner seal part is A V-shaped protrusion projecting inward is formed, and a vaporization part is formed in a part of the outer seal part to communicate the outside air with the non-sealed part.

When the packaging container configured in Patent Document 1 is heated in a microwave oven, steam is generated within the main body due to the heating, and the internal pressure increases. At this time, the peeling region on the flange portion of the sealing film tends to spread concentrically, and a peeling force is applied to the sealing film on the protrusion from the radial direction and the circumferential direction. As a result, the protrusion part peels off earlier than other parts, and the steam is exhausted through the vaporization part. Therefore, it is possible to prevent the contents from scattering due to rupture of the packaging container due to an increase in internal pressure.

However, according to the packaging container of Patent Document 1, it is necessary to change the shape of the seal head in accordance with the shapes of the inner seal part and the outer seal part, and there is a problem that the cost of the packaging container increases.
A packaging container disclosed in Patent Document 2 has been proposed to solve this problem.

Japanese Patent Application Publication No. 10-236542 Japanese Patent Application Publication No. 2018-193119

The packaging container of Patent Document 2 has a printed part in which an ink containing a conductive polymer is arranged between a base layer of a sealing film (lid material) and a thermal adhesive layer, and a non-printed part in which no ink is arranged. A vaporization hole is formed by causing the sealing film to peel off or penetrate through the sealing film due to softening of the thermal adhesive layer at a location having the printed part within the surface of the packaging container, It discharges steam.

However, in the embodiment of Patent Document 2 in which the sealing film of the packaging container is peeled off, there were frequent cases where the sealing film did not peel off at the location where the printed portion was located when heating in a microwave oven. If such a case occurs, there is a risk that the thin plastic film that makes up the container body may be deformed. In addition, when the container body is made of paper, thermal deformation does not occur like with a plastic container body, but the amount of heat stored in the paper container body increases, and the container body may become so hot that it cannot be held by hand. , there is a risk that the container body may be partially scorched. Further, regardless of whether the container body is made of plastic or paper, if the sealing film does not peel off at the location where the printed portion is located, the internal pressure of the container increases and there is a risk that the contents may protrude explosively.
Further, in the embodiment of Patent Document 2 in which the sealing film of the packaging container is penetrated, there is a risk that components of the sealing film may mix into the packaged material.

An object of the present invention is to provide a container with a lid for heating in a microwave oven, which can increase the reliability of steaming by partially peeling the lid material.

The present invention provides the following [1] to [2].
[1] A container with a lid, which has a flange at the opening and includes a plastic container body for accommodating contents, and a lid material for sealing the container body,
When the average thickness of the flange of the container body is defined as T1, and the average thickness of the portion of the container body other than the flange is defined as T2, the relationship is T2<T1,
The lid material has a base material layer and a sealant layer, and a heat-generating printed layer on a part between the base material layer and the sealant layer or a part of the base material layer on the opposite side of the sealant layer. have,
The lidded container is sealed by a heat-sealed region in which at least a portion of the flange and the sealant layer are heat-sealed,
A lidded container for heating in a microwave oven, which has the heat-generating printed layer in the following areas 1A and 2A when the lidded container is viewed from above.
<Area 1A>
A region connecting a circumferential portion of the outer circumferential edge of the heat-sealing region to a circumferential portion of the inner circumferential edge of the flange.
<Area 2A>
A region continuous from the region 1A and located inside the inner peripheral edge of the flange.

[2] A container with a lid, which has a flange at the opening and includes a paper container body for accommodating contents, and a lid material for sealing the container body,
The basis weight of the paper of the container body is 150 to 400 g/m ² ,
The lid material has a base material layer and a sealant layer, and a heat-generating printed layer on a part between the base material layer and the sealant layer or a part of the base material layer on the opposite side of the sealant layer. have,
The lidded container is sealed by a heat-sealed region in which at least a portion of the flange and the sealant layer are heat-sealed,
A container with a lid for heating in a microwave oven, which has the heat-generating printed layer in the following areas 1B and 2B when the container with a lid is viewed from above.
<Area 1B>
A region connecting a circumferential portion of the outer circumferential edge of the heat-sealing region to a circumferential portion of the inner circumferential edge of the flange.
<Area 2B>
A region continuous from the region 1B and located inside the inner peripheral edge of the flange.

In the container with a lid for heating in a microwave oven of the present invention, the lid material can be partially peeled off to improve the reliability of steaming.

FIG. 1 is a sectional view showing an embodiment of a container with a lid for heating in a microwave oven of the present invention. FIG. 2 is a plan view illustrating an embodiment of the arrangement of a heat-sealing area and a heat-generating print layer of a container with a lid for heating in a microwave oven according to the present invention. FIG. 2 is a plan view illustrating an embodiment of the arrangement of a heat-sealing area and a heat-generating print layer of a container with a lid for heating in a microwave oven according to the present invention. 1 is a sectional view showing an embodiment of a lid material constituting a container with a lid for heating in a microwave oven according to the present invention. 1 is a sectional view showing an embodiment of a lid material constituting a container with a lid for heating in a microwave oven according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a container with a lid for heating in a microwave oven of the present invention. 7 is a sectional view taken along the line I-I' in FIG. 6. FIG. FIG. 2 is a plan view illustrating an embodiment of the arrangement of a heat-sealing area and a heat-generating print layer of a container with a lid for heating in a microwave oven according to the present invention. FIG. 2 is a plan view illustrating an embodiment of the arrangement of a heat-sealing area and a heat-generating print layer of a container with a lid for heating in a microwave oven according to the present invention. FIG. 2 is a plan view illustrating an embodiment of the arrangement of a heat-sealing area and a heat-generating print layer of a container with a lid for heating in a microwave oven according to the present invention. FIG. 2 is a plan view illustrating an embodiment of the arrangement of a heat-sealing area and a heat-generating print layer of a container with a lid for heating in a microwave oven according to the present invention. 11 is a partially enlarged view of FIG. 10. FIG.

Hereinafter, the container with a lid for heating in a microwave oven of the present invention will be explained in detail. Note that the numerical range notation "AA to BB" in this specification means "more than or equal to AA and less than or equal to BB."

[Embodiment A]
First, an embodiment of a container with a lid for heating in a microwave oven according to Embodiment A will be described.
A container with a lid for heating in a microwave oven according to Embodiment A of the present invention includes a container body made of plastic that has a flange at the opening and accommodates the contents, and a lid material that seals the container body. It is a container with a lid, and when the average thickness of the flange of the container body is defined as T1, and the average thickness of the portion of the container body other than the flange is defined as T2, there is a relationship of T2<T1, and the lid material is: The lid includes a base material layer and a sealant layer, and a heat-generating printed layer on a part between the base material layer and the sealant layer or a part of the base material layer on the opposite side of the sealant layer. The container with a lid is sealed by a heat-sealed region in which at least a portion of the flange and the sealant layer are heat-sealed, and when the container with a lid is viewed from above, the heat-generating printed layer is sealed in the following region 1A. and area 2A.
<Area 1A>
A region connecting a circumferential portion of the outer circumferential edge of the heat-sealing region to a circumferential portion of the inner circumferential edge of the flange.
<Area 2A>
A region continuous from the region 1A and located inside the inner peripheral edge of the flange.

FIG. 1 is a sectional view showing an embodiment of a container with a lid for heating in a microwave oven according to Embodiment A of the present invention.
A lidded container 100 for heating in a microwave oven shown in FIG. 1 includes a container body 10 and a lid member 20 for sealing the container body. Further, the container main body 10 has an opening 11 on the upper surface, and a flange 12 on the outer peripheral edge of the opening 11. Further, as shown in FIG. 1, the opening 11 is sealed by a heat-sealed region H formed by heat-sealing the flange and the sealant layer. Reference numeral 26a in FIG. 1 indicates a region having a heat-generating printed layer. "N" in FIG. 1 indicates contents such as food.

FIG. 2 and FIG. 3 are plan views showing an embodiment of the arrangement of the heat-sealing area and the heat-generating printed layer of the container with a lid for heating in a microwave oven according to Embodiment A of the present invention.
In FIGS. 2 and 3, the area having the heat-generating printed layer is indicated by the reference numeral 26a. The container with a lid for heating in a microwave oven shown in FIGS. 2 and 3 has a heat-generating printed layer connected to a region connecting a circumferential portion of the outer circumferential edge H2 of the heat-sealing region to a circumferential portion of the inner circumferential edge 12a of the flange. region 1A), and a region (region 2A) that is continuous from region 1A and is inside the inner peripheral edge 12a of the flange. In addition, the container 100 with a lid for heating in a microwave oven in FIG. ).

《Container body》
The container body has a flange at the opening and is made of plastic. Furthermore, when the average thickness of the flange of the container body is defined as T1, and the average thickness of the portion of the container body other than the flange is defined as T2, the relationship is T2<T1.
A plastic container can be manufactured, for example, by vacuum forming or pressure forming a sheet-like plastic film, or by injection molding a thermoplastic plastic. In a plastic container manufactured in this manner, the average thickness (T2) of a portion of the container body other than the flange may be thinner than the average thickness (T1) of the flange. Furthermore, when heated in a microwave oven, the heat of the contents is easily transferred to parts of the container body other than the flange. Therefore, in a plastic container with a relationship of T2<T1, parts of the container body other than the flange tend to be easily deformed by heat when heated in a microwave oven.
In Embodiment A of the present invention, by configuring the heat-generating printed layer to be provided in region 1 and region 2, it is possible to increase the certainty that the lid material will peel off and evaporate, and prevent the pressure and temperature inside the container from rising excessively. By suppressing this, it is possible to suppress deformation of a plastic container having the relationship T2<T1.

The average thickness (T1) of the flange shall be calculated from ten arbitrary locations on the flange. Moreover, the average thickness (T2) of the parts other than the flange of the container main body shall be calculated from arbitrary 10 parts other than the flange of the container main body. However, since the corners of plastic containers are often thick, it is preferable to calculate T2 excluding the corners. In addition, it is preferable to select the location where the thickness is measured from a location along D1, which is the stretching direction of the heat-generating printed layer from the outside to the inside when the lidded container is viewed from above (in the stretching direction of the heat-generating printed layer). For some D1, see FIGS. 2 and 3).
In this specification, the stretching direction D1 of the heat-generating printed layer is, for example, the direction connecting the midpoint of a line that forms the outer edge of the heat-generating printed layer and the midpoint of a line that forms the inner edge of the heat-generating printed layer. It can be calculated.

Plastics constituting the container body include polyethylene, polypropylene, polyethylene terephthalate, and the like. Among these, polypropylene is preferred from the viewpoint of oil resistance and heat resistance to oil contained in the contents. Note that the plastic that constitutes the container body may be a single layer or a multilayer.

Examples of polypropylene include highly crystalline propylene homopolymers, and further examples include polymers of propylene and α-olefins such as ethylene, butene-1, pentene-1, 3-methylbutene-1, and 4-methylpentene-1. Examples include random copolymers. Among these, highly crystalline propylene homopolymers are preferred.

When the container body is formed from plastic, it can be formed by, for example, vacuum forming, pressure forming, injection molding, blow molding, extrusion molding, calendar molding, cast molding, or the like. In this case, a pigment may be added to the molding material in addition to the thermoplastic resin in order to improve the concealability of the container body.

The absolute values of the average thickness of the flange of the container body (T1) and the average thickness of the parts of the container body other than the flange (T2) cannot be definitively determined because they vary depending on the strength required of the container and the manufacturing method of the container. Usually, the average thickness (T1) of the flange is about 0.4 to 4 mm, and the average thickness (T2) of the portion of the container body other than the flange is about 0.1 to 2 mm.
In Embodiment A of the present invention, it is preferable that T2 be as thin as about 0.1 to 0.5 mm because the effect can be more pronounced. Further, in Embodiment A of the present invention, it is preferable that T1-T2 is 0.1 mm or more because the effect can be more pronounced. The upper limit of T1-T2 is about 2 mm.

The container body 10 is provided with an opening 11 on the top surface. Further, the container body 10 is provided with a flange 12 on the outer peripheral edge of the opening 11.
The shape of the container main body 10 may be any shape as described above, and the shape beyond that is not limited. For example, although the container body in FIGS. 2 and 3 has a substantially rectangular shape in plan view, it may have a circular or elliptical shape. Further, although the opening of the container body in FIG. 1 is larger than the bottom, the sizes of the bottom and the opening may be approximately the same, or the opening may be smaller than the bottom. . Further, although the container main body in FIG. 1 has a flat bottom, the container main body may have legs. Further, although the flange of the container main body in FIG. 1 is flat, the flange may have an annular shape.
Note that when the contents are liquid, the microwave absorption efficiency of the region 2A may decrease in a flat table type microwave oven. Therefore, from the viewpoint of making it easier to exhibit the effects of Embodiment A of the present invention when the contents are liquid, it is preferable that the opening of the container body is larger than the bottom.

The depth of the container body 10 is not particularly limited, but is approximately 10 to 200 mm, preferably 10 to 100 mm.

The width of the flange is preferably about 2 to 15 mm from the viewpoint of sealability and easy peelability.

The flange may have a protrusion that protrudes toward the center of the container body. By having a protruding part on a part of the flange, when heating in a microwave oven, the load based on the internal pressure of the sealed container is concentrated on the part corresponding to the protruding part in the heat seal area, and the part is peeled and vaporized to reduce the internal pressure. can be made easier to escape. However, if the flange has a protrusion, it is necessary to change the shape of the seal head, and even if the packaging container of Embodiment A of the present invention does not have a protrusion on a part of the flange, the lid material may partially Considering that the flange can be peeled and steamed, it is preferable that the flange has no protrusion.

《Lid material》
The lid material has a base material layer and a sealant layer, and is configured to have a heat-generating printed layer in a part between the base material layer and the sealant layer or in a part of the base material layer on the opposite side of the sealant layer. be done.
The sealant layer is arranged on the inner layer side of the base layer (the side closer to the container body than the base layer).

4 and 5 are cross-sectional views showing embodiments of the lid material 20. FIG.
The lid material 20 in FIGS. 4 and 5 has a base material layer 21 and a sealant layer 25, and has a heat-generating printed layer 26 in a portion between the base material layer 21 and the sealant layer 25. Furthermore, the lid material 20 shown in FIGS. 4 and 5 has a pattern layer 23.

-Base material layer-
The base material layer is preferably one or more selected from plastic films and paper base materials.
Plastic films are preferred because they have relatively good gas barrier properties, and paper base materials are preferred because they have relatively good dead-hold properties (the ability to maintain a state that has undergone deformation such as bending and twisting).
Note that when the base material layer includes a paper base material, the paper base material absorbs microwaves from a microwave oven. Therefore, from the viewpoint of making it easier to exhibit the effects of Embodiment A of the present invention, it is preferable that the base material layer does not contain a paper base material. On the other hand, from the viewpoint of easily suppressing the formation of through holes in the lid material, it is preferable that the base material layer of the lid material contains a paper base material. In addition, when using a paper base material, from the viewpoint of microwave absorption efficiency, it is preferable to form a heat-generating printed layer on the outer layer side of the paper base material.

The base material layer 21 may be a single layer as shown in FIGS. 4 and 5, but it may also have a multilayer structure formed by adhering two or more plastic films and/or paper base materials. Furthermore, when the base material layer includes two or more plastic films and/or paper base materials, it may contain a plurality of the same kind of materials or different kinds of materials.

As the plastic film of the base material layer, from the viewpoint of heat resistance, it is preferable to use one or more of polyester films such as polyethylene terephthalate, polyamide films such as nylon, and the like. Note that nylon is preferable because it has excellent puncture strength and thus easily prevents the lid material from tearing when filling with solid contents or stacking containers.
Furthermore, when at least one of a polyester film and a polyamide film having excellent heat resistance is used as the base material layer, a plastic film having insufficient heat resistance when used alone can also be used in combination. For example, by using a plastic film with excellent gas barrier properties such as an ethylene-vinyl alcohol copolymer resin film or a polyvinylidene chloride film together with at least one of a polyester film and a polyamide film, the heat resistance and gas barrier properties of the laminate as a whole can be improved. can be made good.

The plastic film may be uniaxially stretched or biaxially stretched. Further, the plastic film may be formed by an inflation method or a melt extrusion coating method.

The thickness of the plastic film is not particularly limited, but is usually about 5 to 50 μm, preferably 10 to 40 μm, and more preferably 12 to 25 μm.
The basis weight of the paper base material is not particularly limited, but is usually about 20 to 200 g/m ² , preferably 50 to 170 g/m ² , and more preferably 70 to 150 g/m ² .

The total light transmittance of the plastic film according to JIS K7361-1:1997 is preferably 85% or more, more preferably 90% or more. Further, the haze of the plastic film according to JIS K7136:2000 is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less.
By setting the total light transmittance and haze within the above ranges, the visibility of the pattern can be easily improved when the pattern layer is formed on the inner layer side of the plastic film.

-Sealant layer-
The sealant layer 25 is partially heated by a seal head or the like, so that it comes into close contact with at least a portion of the flange 12 to form a heat seal area H, and has the role of sealing the opening of the container body.
The sealant layer 25 may be a single layer of a sealing layer, but is preferably composed of a laminate of a core layer and a sealing layer. The core layer contacts the base layer and the seal layer contacts the flange.

(core layer)
The core layer serves as a support for the sealing layer. Furthermore, since the core layer has good adhesion to the base material layer and the seal layer, peeling can occur between the flange and the seal layer when the container is opened after heating in a microwave oven.
From the viewpoint of adhesion with the seal layer, the core layer is preferably made of polypropylene resin. Examples of the polypropylene resin include polypropylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer, and the like. In particular, a propylene-ethylene block copolymer with an excellent balance of impact resistance and rigidity is preferred. The ratio of the propylene component to the ethylene component in the propylene-ethylene block copolymer is preferably 60:40 to 90:10, more preferably 70:30 to 85:15 in terms of mass ratio.

Propylene-ethylene block copolymers have higher rigidity and softening point than propylene-ethylene random copolymers. Therefore, compared to a propylene-ethylene random copolymer, when the lid material is peeled off from the container after heating in a microwave oven, it can maintain appropriate rigidity, and the sealing layer in the heat seal area and the interface with the flange can be The force of peeling off is easily transmitted. That is, by using a propylene-ethylene block copolymer as the core layer, it is possible to easily improve the releasability, and it is also possible to achieve the effect that the peeled surface has a good appearance. In particular, when the seal layer contains an olefin elastomer as described below, the seal layer is softened by heating in a microwave oven, so using a propylene-ethylene block copolymer as a highly rigid core layer can reduce the tension. This makes it easier to transmit the force of peeling.

(Seal layer)
The sealing layer is partially heated by a sealing head or the like to form a heat-sealed region by coming into close contact with at least a portion of the flange. For this reason, it is preferable that the sealing layer is made of a thermoplastic resin having heat-sealing properties.

Moreover, it is preferable that the sealing layer has easy-peel properties so that it can be easily peeled off from the container body. In addition, in this specification, "good easy peelability" does not simply mean that the peel strength is weak, but rather has an adhesive force that is sufficient to ensure sealing performance, but has an excessively strong peel strength upon peeling. It means never.

The sealing layer consists of a first resin that has good adhesion to the resin constituting the flange, and a second resin that does not have good adhesion to the resin constituting the flange and is incompatible with the first resin. It is preferable to form by mixing with resin.
Such resins vary depending on the type of resin that makes up the flange, so it cannot be generalized, but if the resin that makes up the flange is polypropylene resin, polypropylene is used as the first resin, and polyethylene and polyethylene are used as the second resin. It is preferable to use one or more selected from olefin elastomers. That is, when the resin constituting the flange is polypropylene, the sealing layer may be formed from a mixed resin of polypropylene as the first resin and one or more types selected from polyethylene and olefin elastomer as the second resin. preferable. The second resin preferably contains polyethylene from the viewpoint of transparency, and particularly preferably contains an olefin elastomer from the viewpoint of impact resistance and puncture resistance after heating in a microwave oven.

Examples of the first resin, polypropylene (A), include propylene homopolymers, propylene-ethylene block copolymers, and propylene-ethylene random copolymers. Among these, propylene-ethylene block copolymers are preferred because of their excellent impact resistance.
The ratio of the propylene component to the ethylene component in the propylene-ethylene random copolymer is preferably from 60:40 to 99:1, more preferably from 70:30 to 98:2 by mass.

The propylene-ethylene block copolymer can be produced by polymerizing raw materials propylene and ethylene in the presence of a catalyst. Examples of the catalyst include Ziegler-Natta catalyst and metallocene catalyst.

As the second resin (B), one or more selected from polyethylene (B1) and olefin elastomer (B2) can be used.

Examples of polyethylene (B1) include linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE). As the polyethylene, it is preferable to use linear low density polyethylene (LLDPE), and it is more preferable to use linear low density polyethylene (LLDPE) and high density polyethylene (HDPE).

Low density polyethylene is polyethylene with a density of 0.910 to 0.925 g/cm ³ . Medium density polyethylene is polyethylene with a density of 0.926 to 0.940 g/cm ³ . High-density polyethylene is polyethylene with a density of 0.941 to 0.965 g/cm ³ .
Low-density polyethylene is obtained, for example, by polymerizing ethylene at a high pressure of 1000 atm or more and less than 2000 atm. Medium-density polyethylene and high-density polyethylene are obtained, for example, by polymerizing ethylene at medium or low pressures of 1 atm or more and less than 1000 atm.
Linear low-density polyethylene is obtained by copolymerizing α-olefin into a linear polymer obtained by polymerizing ethylene at medium or low pressure to introduce short chain branches. Examples of α-olefins include 1-butene, 1-hexene, 4-methylpentene, 1-octene, and the like.
The linear low density polyethylene preferably has a density of 0.915 to 0.945 g/cm ³ .

Medium density polyethylene and high density polyethylene may partially contain a copolymer of ethylene and α-olefin. Furthermore, even when ethylene is polymerized at medium or low pressure, polyethylene of medium density or low density can be produced if a copolymer of ethylene and α-olefin is included. Such polyethylene is referred to as the above-mentioned linear low density polyethylene.

Examples of the olefin elastomer (B2) include hydrogenated styrene elastomer and ethylene-α-olefin elastomer.
The hydrogenated styrenic elastomer has a structure consisting of a polymer block A mainly composed of at least one vinyl aromatic compound and a polymer block B mainly composed of at least one hydrogenated conjugated diene compound. .
The ethylene-α-olefin elastomer is preferably a random copolymer of ethylene as a main component and an α-olefin, such as ethylene-propylene random copolymer, ethylene-butene random copolymer, ethylene- Examples include propylene-butene random copolymers.

It is preferable that the seal layer contains the olefin elastomer (B2) because it facilitates good adhesion with the core layer. Further, it is preferable that the sealing layer contains the olefin elastomer (B2) because it facilitates improving the puncture resistance and impact resistance of the lid material.
When the seal layer contains the olefin elastomer (B2), the seal layer tends to soften when heated in a microwave oven. The content of olefin elastomer in the sealing layer has been adjusted to prevent the sealing layer from softening due to heating in a microwave oven, resulting in a sticky feeling when peeled off, or deteriorating the aesthetic appearance by stretching into threads. is preferably 2 to 10% by mass. For example, when the seal layer contains polypropylene (A), polyethylene (B1), and olefin elastomer (B2), the ratio of each component is "polypropylene (A) ≧ polyethylene (B1) ≧ olefin elastomer (B2) (mass %)" is preferably satisfied. Specifically, the seal layer preferably contains polypropylene (A): 50 to 80% by mass, polyethylene (B1): 10 to 40% by mass, and olefin elastomer (B2): 2 to 10% by mass.

The first resin, polypropylene (A), and the second resin (B) have low compatibility. Therefore, the polypropylene (A) and the second resin (B) tend to have a structure in which the second resin (B) is arranged like an island in a sea of polypropylene (A) in the sealing layer. In this way, since the polypropylene (A) and the second resin (B) have a sea-island structure, it is easy to adjust the peel strength that can provide peel vaporization property and easy peel property while ensuring initial adhesion. can.

The thickness of the sealing layer is preferably 1 to 10 μm, more preferably 1 to 8 μm. The thickness of the core layer is preferably 20 to 90 μm, more preferably 25 to 90 μm. Further, the thickness of the sealant layer (the total thickness of the seal layer and the core layer) is preferably 20 to 100 μm, more preferably 30 to 50 μm. The thickness of the core layer relative to the thickness of the sealant layer is more preferably 0.5 to 20%.

The sealant layer can be formed, for example, by mixing the resins forming the seal layer described above and coextruding the mixture together with the resin forming the core layer. Alternatively, it can be formed by mixing the above-mentioned resins and melting and extruding the mixture onto the film that will become the core layer. Note that, in order to suppress shrinkage during heat sealing, it is preferable that the obtained sealant layer is not subjected to stretching treatment.

-Heat-generating printing layer-
The heat-generating printing layer is formed on a part between the base material layer and the sealant layer or on a part of the base material layer on the side opposite to the sealant layer.
From the viewpoint of effectively transmitting heat to the sealant layer, the heat-generating print layer is preferably formed in a portion between the base layer and the sealant layer.

The heat-generating print layer is a layer that generates heat by absorbing microwaves, and includes a material that absorbs microwaves. Since the containers with lids of Embodiment A and Embodiment B described below have a heat-generating print layer formed in a specific area, when heated in a microwave oven, a part of the heat-sealed area of the container with a lid is exposed to heat-generating prints. The heat generated in the layer allows it to be peeled off and vaporized. Such steaming is sometimes referred to as "automatic steaming."
Materials that absorb microwaves include conductive particles and conductive polymers. Among these, conductive polymers are preferable because they have good visible light transparency and are less likely to cause sparks due to microwaves.

Examples of the conductive particles include carbon black, silver, aluminum, and ITO (indium tin oxide).

As the conductive polymer, one or more compounds selected from polythiophenes, polypyrroles, polyanilines, polyacetylenes, polyphenylenes, polyphenylene vinylenes, polyacenes, and polythiophene vinylenes are preferred. Moreover, when using a conductive polymer, it is more preferable to further include a dopant.
Dopants include halogens, Lewis acids, protonic acids, organic carboxylic acids, transition metal halides, electrolyte anions, organic cyano compounds, quinones, alkali metals, alkaline earth metals, amino acids, nucleic acids, surfactants, pigments, Alkylammonium ions and quaternary phosphonium salts are mentioned.

When using conductive particles as the conductive agent, the heat-generating print layer preferably contains a binder resin. Further, even when using a conductive polymer as a conductive agent, other resins may be contained in order to adjust the conductivity.

Examples of binder resins used with conductive particles and resins used with conductive polymers include polyolefin resins such as polyethylene resins and chlorinated polypropylene resins, poly(meth)acrylic resins, polyvinyl chloride resins, and polyvinyl chloride resins. Vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polystyrene resin, styrene-butadiene copolymer, vinylidene fluoride resin, polyvinyl alcohol resin, polyvinyl acetal resin, polyvinyl butyral resin, polybutadiene resin, Polyester resin, polyamide resin, alkyd resin, epoxy resin, unsaturated polyester resin, thermosetting poly(meth)acrylic resin, melamine resin, urea resin, polyurethane resin, phenolic resin, xylene based resins, maleic acid resins, cellulose resins such as nitrocellulose, ethyl cellulose, acetyl butyl cellulose, and ethyloxyethyl cellulose, rubber resins such as chlorinated rubber and cyclized rubber, petroleum resins, natural resins such as rosin, casein, etc. can be mentioned.

The heat-generating printing layer may further contain, if necessary, fillers, stabilizers, plasticizers, antioxidants, light stabilizers such as ultraviolet absorbers, dispersants, thickeners, desiccants, lubricants, and crosslinking agents. It is possible to add arbitrary additives such as.

The area of the heat-generating printed layer is preferably 1 cm ² or more, more preferably 1 to 12 cm ² , and even more preferably 3 to 8 cm ² .
By setting the area of the heat-generating printed layer to 1 cm ² or more, it is possible to easily provide the necessary minimum amount of heat to cause the lid material to peel off. Furthermore, by setting the area of the heat-generating printed layer to 12 cm ² or less, it is possible to prevent the area for peeling and steaming from becoming excessive, which would impede the degree of cooking of the contents.

The thickness of the heat-generating printed layer is preferably 0.1 to 5 μm, more preferably 0.2 to 3 μm.
By setting the thickness of the heat-generating printed layer to 0.1 μm or more, it is possible to easily provide the necessary minimum amount of heat to cause the lid material to peel off. In addition, by setting the thickness of the heat-generating print layer to 5 μm or less, the heat-generating print layer is prevented from becoming unnecessarily high temperature, and the lid material is prevented from deforming or through-holes are formed in the lid material. It's easy to do.

The length of the heat generating printed layer is preferably 5 to 60 mm, more preferably 10 to 40 mm. In this specification, the "length of the heat-generating print layer" means the length of the heat-generating print layer in the circumferential direction of the flange.
By setting the length of the heat-generating printed layer to 5 mm or more, steam can be easily discharged to the outside. Further, by setting the length of the heat-generating printed layer to 60 mm or less, it is possible to suppress excessive discharge of steam to the outside, and to easily suppress the possibility that it interferes with the cooking of the contents.

The shape of the heat-generating printed layer when the lidded container is viewed from above is not particularly limited, and may be approximately square or rectangular as shown in FIGS. 2 and 3, or may be trapezoidal. It may be of any other shape. Note that when the planar view shape is a trapezoid, either the inner or outer sides may be longer, but a trapezoid with longer inner sides is preferable (see FIG. 11).

When the length of the outer heat-generating print layer is defined as L1 and the length of the inner heat-generating print layer is defined as L2 when the lidded container is viewed from above, it is preferable that L1≠L2. By setting L1≠L2, the amount of steam released to the outside after steaming can be appropriately controlled.
Further, when L1≠L2, the relationship may be L1>L2, but preferably the relationship L1<L2. Since the internal pressure inside the container is transmitted concentrically, by satisfying the relationship L1<L2, the lid material can be peeled off more easily.
Further, it is more preferable that the heat-generating print layer satisfying the relationship L1<L2 satisfies the relationship that the length continuously decreases from the outside toward the inside. The heat-generating printed layer in FIG. 11 has long inner sides and satisfies this relationship.
L1/L2 is preferably 0.30 to 0.90, more preferably 0.50 to 0.80, even more preferably 0.60 to 0.70.
L1 and L2 are preferably adjusted within the above-mentioned length of the heat-generating printed layer (5 to 60 mm).

The heat-generating print layer can be formed, for example, by applying a heat-generating print layer forming ink containing a material constituting the heat-generating print layer onto the base layer or the intermediate base layer and drying it.

It is preferable that D1, which is the extending direction of the heat-generating printed layer from the outside to the inside when the lidded container is viewed from above, and D2, which is the direction perpendicular to the tangent to the inner peripheral edge of the flange, are substantially parallel.
By making D1 and D2 substantially parallel, the lid material can be easily peeled and steamed. Note that "substantially parallel" means that the angle formed by D1 and D2 is 5 degrees or less, preferably 3 degrees or less, more preferably 2 degrees or less, and still more preferably 1 degree or less.

A region having a heat-generating printed layer within the plane of the lid material is defined as a heat-generating region. Further, the center point of the lid material is defined as X, and the midpoint of the line forming the outer peripheral edge of the heat generating area is defined as Y. In this case, it is preferable that the lid material satisfies the following condition (1).
<Condition 1>
Resistance value of the heat-generating print layer in the XY direction<resistance value of the heat-generating print layer in the direction orthogonal to the XY direction

The "XY direction in the plane of the lid material", which is the reference direction for condition 1, means the ideal direction for peeling vaporization.
Condition 1 stipulates that the resistance value of the heat-generating print layer in the XY direction is smaller than the resistance value of the heat-generating print layer in the direction orthogonal to the XY direction. Although the detailed cause is unknown, by making the resistance value of the heat-generating print layer in the XY direction smaller than the resistance value of the heat-generating print layer in the direction orthogonal to the XY direction, it is possible to facilitate peeling and vaporization.

The heat-generating print layer can be formed by applying a heat-generating print layer forming ink onto the support while conveying the support such as the base material layer in the machine direction (MD direction), and drying the ink. When the heat-generating print layer forming ink is applied onto the support in this manner, the conductive component contained in the ink is oriented in the flow direction (MD direction). For this reason, while the resistance value in the flow direction (MD direction) becomes low, the resistance value in the width direction (TD direction) becomes high, and it is thought that anisotropy in the resistance value occurs.
Therefore, by determining the pattern shape and punching direction of the heat-generating ink layer in consideration of the orientation of the conductive component in the MD direction, a lid material that satisfies Condition 1 can be obtained.

In this specification, the resistance value of the heat-generating printed layer is measured by a two-terminal method at a constant current (60 A of direct current) and a distance between measurements of 5 mm. Examples of the measuring device include the product name "KEW MATE MODEL 2000A" manufactured by Kyoritsu Electric Meter Co., Ltd.
Furthermore, in this specification, various measurements such as resistance values are performed in an atmosphere with a temperature of 23° C.±5° C. and a humidity of 40 to 65%, unless otherwise specified. Furthermore, before each measurement, the measurement sample shall be exposed to the atmosphere for 30 minutes or more.

Ratio of the resistance value of the heat generating print layer in the XY direction to the resistance value of the heat generating print layer in the direction orthogonal to the XY direction (resistance value of the heat generating print layer in the XY direction/resistance value of the heat generating print layer in the direction orthogonal to the XY direction) is preferably 0.70 to 0.95, more preferably 0.80 to 0.93.

The resistance value of the heat generating printed layer in the XY direction is preferably 1.5 kΩ or more and 100 kΩ or less, more preferably 1.7 kΩ or more and 50 kΩ or less, even more preferably 2.0 kΩ or more and 30 kΩ or less. It is even more preferable that the resistance is 5 kΩ or more and 15 kΩ or less.
By setting the resistance value to 1.5 kΩ or more, it is possible to suppress excessive heat generation of the heat-generating printed layer and to easily suppress problems such as formation of through holes in the lid material. In addition, by setting the resistance value to 100 kΩ or less, the heat-generating printed layer can appropriately generate heat and facilitate peeling and steaming.

The container with a lid of Embodiment A of the present invention is required to have heat-generating printed layers in the following regions 1A and 2A when the container with a lid is viewed from above.
<Area 1A>
A region connecting a circumferential portion of the outer circumferential edge of the heat-sealing region to a circumferential portion of the inner circumferential edge of the flange.
<Area 2A>
A region continuous from the region 1A and located inside the inner peripheral edge of the flange.

In order to peel and vaporize a container with a lid using the heat-generating print layer, it is considered that the heat-generating print layer should be formed only in the area corresponding to the heat seal area where the peel-steam is desired. However, if the heat-generating printed layer is formed only in the area corresponding to the heat-sealing area, the lid material will not peel and evaporate at the location where the heat-generating printed layer is located, and deformation of the plastic container in the relationship of T2<T1 cannot be suppressed. was there.
In the container with a lid of Embodiment A of the present invention, when the container with a lid is viewed from above, the heat-generating printed layer is provided in the region 1A and the region 2A, so that the lid material is peeled off and vaporized at the location where the heat-generating printed layer is provided. This increases reliability and makes it possible to suppress deformation of the plastic container in the relationship of T2<T1.

Having the heat-generating printed layer in the area 1A means that even if the inner circumferential edge H1 of the heat-sealing area does not reach the inner circumferential edge 12a of the flange, the heat-generating printed layer extends from the outer circumferential edge H2 of the heat-sealing area to the inner circumferential edge 12a of the flange. It means to have.
In FIGS. 2 and 3, the area designated by the symbol W1 in the area 26a having the heat-generating print layer corresponds to the area 1A.
In this way, since the region 1A reaches the inner circumferential edge 12a of the flange, it is possible to provide the first opportunity to increase the reliability of peeling and vaporization.

However, even if the area 1A has a heat-generating print layer, it is difficult to secure the area of the heat-generating print layer, and therefore the reliability of peeling and vaporization cannot be sufficiently increased. It is easier to secure the area by increasing the length of the heat-generating printed layer, but in that case, the pressure inside the container body is suddenly released to the outside after peeling and steaming, making it impossible to cook properly. For this reason, it is important to have a heat-generating print layer in the region 2A.
Region 2A is a region continuous from region 1A, and is a region inside the inner peripheral edge 12a of the flange. In FIGS. 2 and 3, the area designated by the symbol W2 in the area 26a having the heat-generating print layer corresponds to the area 2A.
Area 2A needs to be continuous from area 1A. This is because if the region 1A and the region 2A are not continuous, the area of the heat-generating print layer will not be increased.
As described above, by having the heat-generating print layer in the area 1A and the area 2A, the area of the heat-generating print layer can be increased, so that the temperature of the heat-generating print layer can be easily raised when heating in a microwave oven. , it is possible to increase the reliability of vaporization by partially peeling off the lid material.

The width W2 of the heat-generating printed layer in the area 2A is preferably 1 to 15 mm, more preferably 2 to 10 mm.
By setting W2 to 1 mm or more, it is possible to easily increase the certainty that the lid material is partially peeled off and vaporized. Furthermore, by setting W2 to 15 mm or less, it is possible to easily prevent the heat-generating print layer from becoming unnecessarily high-temperature.
Note that the width of the heat-generating print layer in the area 2A is the width shown by W2 in FIGS. 2 and 3.

In the lidded container of Embodiment A of the present invention, the outer peripheral edge of the heat sealing area is located inside the lidded container than the outer peripheral edge of the flange, and when the lidded container is viewed from above, It is preferable that the heat generating printed layer is further provided in the following region 3A.
<Area 3A>
A region that is continuous from the region 1A and extends from the outer periphery of the heat seal region to the outer periphery of the flange.

By providing the heat-generating printed layer in the region 3A, it is possible to easily increase the reliability that the lid material is partially peeled off and vaporized. In FIG. 3, the area designated by reference numeral W3 in the area 26a having the heat-generating printed layer corresponds to the area 3A.
In addition, when the outer periphery of the flange and the outer periphery of the heat-sealed area match, the area 3A is included in the range of the area 1A.

Note that if the adhesion of the heat-generating print layer is not good, an anchor coat layer may be provided on the layer (for example, the base material layer) forming the heat-generating print layer.

-Picture layer-
The lid material may have a pattern layer.
The position of the pattern layer is not particularly limited as long as it is closer to the outer layer than the sealant layer, and may be appropriately determined in consideration of the light transmittance of the base layer and the heat-generating print layer.

For example, in the case of having a base material layer with low light transmittance such as paper or an opaque plastic film, the pattern layer is preferably arranged on the outer side of the base material layer with low light transmittance. Further, in the case of having a base material layer with high light transmittance such as a transparent plastic film, from the viewpoint of protecting the picture layer, it is preferable to arrange the picture layer closer to the inner layer than the base material layer with high light transmittance. In addition, in the case of having a plurality of base material layers, the position of the pattern layer may be appropriately determined in consideration of the light transmittance of each base material layer.
In FIGS. 4 and 5, the pattern layer 23 is arranged on the inner side of the base material layer 21. In this case, the base material layer 21 is a highly transparent base material layer.

Moreover, when the light transmittance of the heat-generating print layer is low, it is preferable that the pattern layer is arranged on the outer side of the heat-generating print layer. On the other hand, when the heat-generating print layer has high light transmittance, the pattern layer may be placed on either the inner layer side or the outer layer side of the heat-generating print layer.
Note that when a conductive polymer is used as a material for absorbing microwaves, the heat-generating print layer usually has good light transmittance, and even when conductive particles are used as a material for absorbing microwaves. , it has a predetermined light transmittance as long as it does not contain an excessive amount of conductive particles having a particle size larger than visible light. Therefore, as long as the heat-generating print layer does not have an extreme configuration, the positional relationship between the pattern layer and the heat-generating print layer is not limited.

The pattern layer can form a pattern using a combination of one or more types selected from characters, figures, symbols, patterns, patterns, solid printing, and the like. The pattern layer is not limited to a single layer, but may be a multilayer of two or more layers.
The pattern layer 23 may be formed on the entire surface of the lid material, or may be formed partially, as shown in FIGS. 4 and 5.

The pattern layer mainly contains a colorant and a binder resin.
Coloring agents include white pigments such as titanium dioxide, barium sulfate, magnesium oxide, calcium carbonate, zinc oxide, and lead white; black pigments such as carbon black, titanium black, and iron black; yellow lead, titanium yellow, Bengara, and cadmium. Chromatic inorganic pigments such as red, ultramarine and cobalt blue; chromatic organic pigments such as quinacridone red, isoindolinone yellow and phthalocyanine blue; glittering materials such as pearl pigments and metal scales; dyes, etc.; A species or two or more species can be used.
Examples of the binder resin include those similar to the binder resins exemplified for the heat-generating print layer.

The content of the coloring agent in the pattern layer is not particularly limited, but it is preferably 5 to 70% by mass, more preferably 15 to 65% by mass, and 20% by mass of the total solid content of the pattern layer. More preferably, the amount is 60% by mass.

When a glitter pigment is included as a coloring agent, from the viewpoint of microwave resistance, the glitter pigment is preferably a pearl pigment.
Examples of pearl pigments include white pearl pigments, interference pearl pigments, and colored pearl pigments.

The pearl pigment preferably has an average length of 5 to 70 μm, more preferably 10 to 40 μm.
The average length of the pearl pigment and the average length of the metal scales are the average lengths of any 20 particles (pearl pigments or metal scales) observed with an optical microscope or an electron microscope from the plane direction of the lid material. It is required as. Note that the length of one pearl pigment and metal scale means the maximum length of one pearl pigment and metal scale in the plane direction.

Further, the average thickness of the pearl pigment is preferably 0.01 to 1 μm, more preferably 0.02 to 0.7 μm, and even more preferably 0.05 to 0.5 m.
The average thickness of the pearl pigment and metal scales is determined as the average value of the thickness of 20 arbitrary particles (pearl pigment or metal scales) obtained by observing the cross section of the lid material using an optical microscope or an electron microscope. The thickness of one pearl pigment and metal scale is determined by dividing the cross-sectional image of one pearl pigment and metal scale into five regions of equal length in the length direction, and calculating the thickness of the central part of each region ( t ₁ , t ₂ , t ₃ , t ₄ , t ₅ ) and mean the average of t ₁ to t ₅ .

The content of the pearl pigment is preferably 40 to 90% by mass, more preferably 50 to 85% by mass, and even more preferably 50 to 85% by mass of the total solid content of the pattern layer, from the viewpoint of ensuring a sufficient amount to obtain gloss. is 60 to 80% by mass.

Examples of the material of the metal scales used as the bright pigment include metals and alloys such as aluminum, gold, silver, brass, titanium, chromium, nickel, nickel-chromium, and stainless steel.
Metal scales include, for example, those obtained by vacuum-depositing the metal or alloy on a plastic film, peeling the metal thin film from the plastic film, crushing and stirring the peeled metal thin film, or powder of the metal or alloy. and a solvent, and spread and/or crush the powder using a media stirring mill, ball mill, attritor, etc., or those whose surfaces are coated with a resin can be used. can.

From the viewpoint of uniform dispersion in the pattern layer, the metal scales preferably have an average length of 1 to 50 μm, more preferably 2 to 30 μm, and still more preferably 5 to 20 μm. In addition, from the viewpoint of ease of handling and obtaining high metallic luster, the average thickness is preferably 0.01 to 5 μm, more preferably 0.02 to 3 μm, and even more preferably 0.05 to 1 μm. Further, the aspect ratio (average length/average thickness) of the metal scales is preferably 15 to 500.

The content of metal scales in the pattern layer is preferably 3% by mass or more and 50% by mass or less of the total solid content of the pattern layer, from the viewpoint of the balance between imparting glitter and microwave resistance, and 3% by mass. It is more preferably 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less.

The pattern layer can be formed, for example, by applying a pattern layer forming ink containing a material constituting the pattern layer onto the base layer or the intermediate base layer and drying it.

The thickness of the pattern layer is not particularly limited, and is preferably about 0.3 to 5.0 μm, more preferably 0.5 to 3.0 μm.

-Gas barrier layer-
The lid material may have a gas barrier layer.
The position of the gas barrier layer is not particularly limited as long as it is on the outer side of the sealant layer, but it is preferably between the base layer and the sealant layer.
The positional relationship between the heat-generating printed layer and the gas barrier layer is not particularly limited.
When a pattern layer is included, the positional relationship between the gas barrier layer and the pattern layer is not particularly limited, and either may be on the sealant layer side (inner layer side). In addition, when the gas barrier layer is formed on the outer layer side of the pattern layer, it is preferable that the gas barrier layer is made of a light-transmitting material so that the pattern layer can be visually recognized.
The gas barrier layer can be formed, for example, on a base material layer, an intermediate base material layer described below, and the like.

The gas barrier layer plays a role in blocking the permeation of oxygen, water vapor, and the like. Further, the gas barrier layer may also provide light-shielding properties that block transmission of visible light, ultraviolet rays, and the like. The gas barrier layer may be composed of only one layer, or may be composed of two or more layers.

The gas barrier layer can be formed as a vapor deposited film or a coated film by a known method.
When forming the gas barrier layer on the base material layer or intermediate base material layer, the base material layer or intermediate base material layer may be subjected to surface treatment in advance from the viewpoint of improving adhesion. Examples of the surface treatment include corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas, nitrogen gas, etc., glow discharge treatment, oxidizing agent treatment, and application of an anchor coating agent.

The vapor-deposited film, which is an example of a gas barrier layer, is made of silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium, etc., from the viewpoint of ensuring that the contents can be sufficiently heated by microwaves in a microwave oven. (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), etc. .
Methods for forming the deposited film include, for example, physical vapor deposition (PVD) methods such as vacuum evaporation, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. Laws etc.

The thickness of the deposited film varies depending on the film forming material, required gas barrier performance, etc., but is usually preferably about 5 to 200 nm, more preferably 5 to 150 nm, and even more preferably 10 to 100 nm. In the case of inorganic oxides such as silicon oxide and aluminum oxide, the thickness is preferably about 5 to 100 nm, more preferably 5 to 50 nm, and still more preferably 10 to 30 nm.

A gas barrier coating film, which is an example of a gas barrier layer, has the general formula R ¹ _n M (OR ² ) _m (wherein R ¹ and R ² are organic groups having 1 to 8 carbon atoms, and M is a metal atom). n is an integer of 0 or more, m is an integer of 1 or more, and n+m is the valence of M.) at least one alkoxide represented by An ink obtained by polycondensing an alcohol copolymer with a sol-gel method in the presence of a sol-gel method catalyst, acid, water, and an organic solvent is applied, and at 50 to 300° C., the ink obtained is 0.05 It can be formed by heat treatment for ~60 minutes.
The coating method may be, for example, roll coating such as a gravure roll coater, spray coating, spin coating, dipping, brush coating, bar coating, applicator, or other coating means. The dry thickness of the coating film is preferably about 0.01 to 30 μm, more preferably 0.05 to 20 μm, and even more preferably 0.1 to 10 μm after one or more applications.
The gas barrier coating film is preferably formed on the surface of the deposited film from the viewpoint of improving gas barrier properties.

-Intermediate base material layer-
The intermediate base material layer is used to improve the strength and processability of the lid material, to change the texture of the lid material, or to be used as a base material for forming other layers such as a gas barrier layer. This is a layer provided between the base material layer and the sealant layer as necessary. Examples of the constituent material of the intermediate base layer include a plastic film and a paper base material.
When the lid material has a heat-generating printed layer on the inner side of the plastic film, it is preferable to arrange the intermediate base material layer on the inner side of the heat-generating printed layer.

As the plastic film and paper base material as the intermediate base layer, the same plastic film and paper base material as the base layer described above can be used.
Note that when the intermediate base material layer includes a paper base material, the paper base material absorbs microwaves from a microwave oven. Therefore, from the viewpoint of making it easier to exhibit the effects of Embodiment A of the present invention, it is preferable that the intermediate base material layer does not contain a paper base material.

Considering heating in a microwave oven, the intermediate base material layer preferably has excellent heat resistance. Specific examples of the intermediate base material layer having excellent heat resistance include paper and the plastic film having excellent heat resistance as exemplified in the base material layer.

-Adhesive layer-
Each layer constituting the lid material may be laminated with an adhesive layer interposed therebetween from the viewpoint of improving the bonding strength between each layer.
The thickness of each adhesive layer is preferably about 0.01 to 20 μm, more preferably 0.05 to 15 μm, and still more preferably 0.1 to 10 μm.

The adhesive layer can be formed, for example, by a method using a general-purpose dry laminating adhesive or by a melt extrusion method.
Examples of adhesives for dry lamination include polyvinyl acetate adhesives, polyacrylic ester adhesives, cyanoacrylate adhesives, ethylene copolymer adhesives, cellulose adhesives, polyester adhesives, and polyamide adhesives. Adhesives, polyimide adhesives, amino resin adhesives such as urea resins and melamine resins, phenolic resin adhesives, epoxy adhesives, polyurethane adhesives (for example, cured products of polyol and isocyanate), reactive type Examples include (meth)acrylic acid adhesives, rubber adhesives such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber, silicone adhesives, and inorganic adhesives such as alkali metal silicates and low-melting glass.

- Layer composition of lid material -
Below, embodiments of the layered structure of the lid material will be shown. Note that in (m1) to (m8) below, the layer on the left side is the outer layer side, and "/" indicates the boundary between each layer.
(m1) Plastic film/heat-generating print layer/picture layer/adhesive layer/intermediate plastic film/adhesive layer/sealant layer (m2) plastic film/picture layer/heat-generating print layer/adhesive layer/intermediate plastic film/adhesive Layer/Sealant layer (m3) Plastic film/Gas barrier layer/Heat-generating print layer/Picture layer/Adhesive layer/Intermediate plastic film/Adhesive layer/Sealant layer (m4) Plastic film/Heat-heat print layer/Picture layer/Adhesive layer / Gas barrier layer / Intermediate plastic film / Adhesive layer / Sealant layer (m5) Plastic film / Heat-generating print layer / Pattern layer / Intermediate plastic film / Adhesive layer / Sealant layer (m6) Pattern layer / Heat-generating print layer / Paper base material / Adhesive layer / Intermediate plastic film / Adhesive layer / Sealant layer (m7) Pattern layer / Heat-generating print layer / Paper base material / Adhesive layer / Sealant layer (m8) Plastic film / Pattern layer / Heat-generating print layer / Adhesive layer/sealant layer

《Heat seal area》
The lidded container of Embodiment A has a heat-sealed region in which at least a portion of the flange of the container body and the sealant layer of the lid are heat-sealed. The heat seal area allows the lidded container to seal the contents.

It is preferable that the heat-sealing region is continuously formed in a band-like or linear shape so as to go around the flange (FIGS. 2 and 3).
The area of the heat seal area may correspond to the area of the flange. In other words, the sealant layer may be heat sealed to all of the flanges. On the other hand, as shown in FIGS. 1 to 3, the sealant layer may be heat-sealed to a portion of the flange, so that the area of the heat-sealed region and the area of the flange do not have to match.

The width of the heat seal area (the distance between H1 and H2 in FIGS. 2 and 3) is preferably 10% to 100%, more preferably 20 to 80%, of the width of the flange.

"Contents"
The contents stored in the container body of the lidded container of Embodiment A are not particularly limited. Note that when the contents are liquid, the liquid contents absorb microwaves from microwave ovens, so the lid material tends to be difficult to peel off and steam. However, in Embodiment A, even if the contents are liquid, Peeling of the lid material does not interfere with steaming. For this reason, it is preferable that the contents are liquid, since the effects of Embodiment A can be more easily exerted.

[Embodiment B]
Next, an embodiment of a container with a lid for heating in a microwave oven according to Embodiment B will be described.
A container with a lid for heating in a microwave oven according to Embodiment B of the present invention includes a container body made of paper that has a flange at the opening and accommodates the contents, and a lid material that seals the container body. A container with a lid, wherein the paper of the container body has a basis weight of 150 to 400 g/m ² , and the lid material has a base material layer and a sealant layer, and a combination of the base material layer and the sealant layer. The lidded container has a heat-generating printed layer on a part between or on a part of the base layer on the side opposite to the sealant layer, and the container with a lid has at least a part of the flange and the sealant layer heat-sealed. When the lidded container is viewed from above, the heat-generating printed layer is formed in the following regions 1B and 2B.
<Area 1B>
A region connecting a circumferential portion of the outer circumferential edge of the heat-sealing region to a circumferential portion of the inner circumferential edge of the flange.
<Area 2B>
A region continuous from the region 1B and located inside the inner peripheral edge of the flange.

FIG. 6 is a perspective view showing an embodiment of a container with a lid for heating in a microwave oven according to Embodiment B of the present invention, and FIG. 7 is a sectional view taken along the line II' in FIG.
The lidded container 100 for microwave heating shown in FIGS. 6 and 7 includes a container body 10 and a lid 20 for sealing the container body. Further, the container main body 10 has an opening 11 on the upper surface, and a flange 12 on the outer peripheral edge of the opening 11. Further, as shown in FIG. 6, the opening 11 is sealed by a heat-sealed region H in which the flange and the sealant layer are heat-sealed (the shaded area in FIG. 6 is the heat-sealed region H). "N" in FIG. 7 indicates contents such as food.

8 to 11 are plan views showing embodiments of the arrangement of the heat-sealing area and the heat-generating printed layer of a container with a lid for heating in a microwave oven according to Embodiment B of the present invention. Moreover, FIG. 12 is a partially enlarged view of the vicinity of the region 26a having the heat-generating printed layer in FIG.
In FIGS. 8 to 11, the outermost lid member 20 is shown in solid lines, and the constituent members located inside the lid member 20 are shown in broken lines.
In FIGS. 8 to 11, the region having the heat-generating printed layer is indicated by the reference numeral 26a. The container with a lid for heating in a microwave oven shown in FIGS. 8 to 11 has a heat-generating printed layer connected to a region connecting a circumferential portion of the outer circumferential edge H2 of the heat-sealing region to a circumferential portion of the inner circumferential edge 12a of the flange. region 1B), and a region (region 2B) that is continuous from region 1 and is inside the inner peripheral edge 12a of the flange. In addition, the container 100 with a lid for heating in a microwave oven shown in FIGS. 8 to 11 has a heat-generating printed layer in an area continuous from area 1, which is an area from the outer periphery H2 of the heat seal area to the outer periphery 12b of the flange. (area 3B). Furthermore, the lidded container 100 for microwave heating shown in FIGS. 10 and 11 has a heat-generating printed layer in a region (region 4B) that is continuous from region 1B and is outside the outer peripheral edge 12b of the flange. There is. In FIG. 12, the area 1B is indicated by i, the area 2B is indicated by ii, the area 3B is indicated by iii, and the area 4B is indicated by iv.

《Container body》
The container body has a flange at the opening and is made of paper. When such a paper container body is heated in a microwave oven, the amount of heat stored in the flange increases, and the container body may become so hot that it becomes impossible to hold it by hand. Additionally, if the flange accumulates too much heat, there is a risk of scorching.
The reason why the vicinity of the flange of the paper container body becomes hot is thought to be as follows.

First, a paper container body having a flange at the opening tends to wrinkle near the boundary between the flange and the body of the container body and near the boundary between the body and the bottom of the container body. This is because the area near the boundary described above is bent during molding. In the areas where wrinkles occur in this way, areas where the density of the paper is high and areas where the density of the paper is low coexist.
On the other hand, paper contains water, and water absorbs microwave radiation. Furthermore, cellulose, the raw material for paper, also easily absorbs microwaves.
Therefore, in the areas where the density of the paper of the wrinkled paper container body is increased as described above, the amount of heat generated locally increases, and the amount of heat stored locally increases.
Even if the paper container body stores heat as described above, if the container body is filled with contents, the heat tends to be absorbed by the contents. However, since the flange of the container body does not come into contact with the contents, the stored heat is not absorbed by the contents.
Furthermore, in a container with a lid made by heat-sealing a paper container body with a lid material, the contents generate heat when heated in a microwave oven, and the internal temperature rises. This internal temperature continues to rise until the lid material partially peels off and evaporates, but as mentioned above, paper absorbs microwaves, so the lid material is heat-sealed to the opening of the paper container body. The lid material of such packaging containers tends to be difficult to peel off and allow steam to pass through.
From the above, in a container with a lid that is formed by heat-sealing the flange of a paper container body with a lid material, the temperature near the flange of the container body tends to rise.

Note that the wrinkles that occur on the flange can be smoothed by smoothing treatment (for example, ultrasonic processing described in JP-A No. 2000-33927, heat sealing processing described in JP-A No. 2001-328616). can be made less noticeable. However, in the above-described process, the wrinkled surface is crushed to make it appear smoother, so a region with a locally high density of paper remains inside the flange. Therefore, even if a smoothing treatment is performed to make the wrinkles generated on the flange less noticeable, the temperature near the flange will rise during heating in a microwave oven.

In the lidded container for heating in a microwave oven of Embodiment B, the basis weight of the paper constituting the container body is 150 to 400 g/m ² . The basis weight is preferably 250 to 350 g/m ² .
If the basis weight is less than 150 g/m ² , the strength of the container body is insufficient. Furthermore, if the basis weight is less than 150 g/m ² , even if wrinkles occur and the density of the paper increases locally, problems such as an excessive amount of heat storage are unlikely to occur.
On the other hand, if the basis weight exceeds 400 g/m ² , it becomes difficult to mold the shape of the container body. Moreover, when the basis weight exceeds 400 g/m ² , it is difficult to suppress the amount of heat storage in the paper.

In the container with a lid for heating in a microwave oven of Embodiment B, by having the heat-generating printed layer in the areas 1B and 2B, it is possible to increase the certainty that the lid material will peel off and evaporate. It is possible to suppress the temperature rise near the flange of the container body. The technical significance of region 1B and region 2B will be described later.

The member constituting the container body preferably has a resin layer on both or one side of the paper, from the viewpoint of protecting the packaged material and suppressing the leakage of the liquid packaged material. Further, from the viewpoint of heat insulation, the resin layer may be foamed.
Examples of the resin constituting the resin layer include polyolefin resins such as polyethylene and polypropylene, polyester, and ethylene-vinyl acetate copolymer, with polyolefin being preferred.
The thickness of the resin layer is preferably about 15 to 60 μm. Further, the thickness of the resin layer on the outer layer side of the paper is preferably 15 to 30 μm, and the thickness of the resin layer on the inner layer side of the paper is preferably 25 to 60 μm.

Further, the member constituting the container body may be made by laminating a plastic film to paper for the purpose of increasing the strength and gas barrier properties of the container body. Further, in order to further improve gas barrier properties, the plastic film is preferably a vapor-deposited film.
As the plastic film included in the container body, the same plastic film as exemplified as the base layer of the lid material of Embodiment A can be used.

The container body 10 is provided with an opening 11 on the top surface. Further, the container body 10 is provided with a flange 12 on the outer peripheral edge of the opening 11.
The shape of the container main body 10 may be any shape as described above, and the shape beyond that is not limited. For example, although the container body shown in FIGS. 6 and 7 has a substantially circular bottom and opening, the bottom and opening may have a shape other than circular, such as an ellipse or a square. Furthermore, although the opening of the container body in FIGS. 6 and 7 is larger than the bottom, the sizes of the bottom and the opening may be approximately the same, or the opening may be smaller than the bottom. It's okay. In addition, from the viewpoint of making it easier to exhibit the effects of Embodiment B, it is preferable that the opening of the container body is larger than the bottom.
Further, although the container body in FIGS. 6 and 7 has a flat bottom, the container body may have legs. Further, although the flange of the container body in FIGS. 6 and 7 is flat, the flange may have an annular shape. In addition, from the viewpoint of formability, it is preferable that the container main body has a flat bottom and/or a flat flange. Similarly, from the viewpoint of moldability, the container body is preferably formed from a single member containing paper.

The container body 10 can be formed, for example, by preparing a blank made of members constituting the container body, placing the blank in a mold, and drawing-forming the blank with heat and pressure.
Note that when a blank containing paper is drawn and formed, wrinkles occur near the flange. If wrinkles exist near the flange, the contents will leak even if the lid is closed, so it is preferable to smooth the flange during molding or when sealing the lid material. Examples of methods for smoothing the flange include ultrasonic processing described in JP-A No. 2000-33927 and heat sealing processing described in JP-A No. 2001-328616.

The depth of the container body 10 is not particularly limited, but is about 10 to 100 mm, preferably 10 mm or more and less than 50 mm.

The width of the flange is preferably about 2 to 15 mm from the viewpoint of sealability and easy peelability.

The flange may have a protrusion that protrudes toward the center of the container body. By having a protruding part on a part of the flange, when heating in a microwave oven, the load based on the internal pressure of the sealed container is concentrated on the part corresponding to the protruding part in the heat seal area, and the part is peeled and vaporized to reduce the internal pressure. can be made easier to escape. However, if the flange has a protrusion, it is necessary to change the shape of the seal head, it is difficult to form a protrusion on the flange of a paper container, and the packaging container of Embodiment B of the present invention has a protrusion on the flange. Considering that the lid material can be partially peeled off and vaporized even if the flange does not have a protrusion, it is preferable that the flange does not have a protrusion.

Specific examples of the layer structure of the members constituting the container body include the following (n1) to (n5). Note that "/" indicates the interface between each layer. In addition, in (n1) to (n5) below, the left side represents the outer layer side, and the right side represents the inner layer side (content side). In addition, in (n1) and (n4) below, the foamed resin layer on the outer layer side of the paper has excellent heat insulation properties, so it can be suitably used as a member constituting the body of the container body.
(n1) paper/resin layer (n2) resin layer/paper/resin layer (n3) paper/resin layer/plastic film/resin layer (n4) resin layer/paper/resin layer/plastic film/resin layer (n5) paper /Adhesive layer/Vapour-deposited plastic film/Resin layer

《Lid material》
The lid material has a base material layer and a sealant layer, and is configured to have a heat-generating printed layer in a part between the base material layer and the sealant layer or in a part of the base material layer on the opposite side of the sealant layer. be done.
The sealant layer is arranged on the inner layer side of the base layer (the side closer to the container body than the base layer).

4 and 5 are cross-sectional views showing embodiments of the lid material 20. FIG.
The lid material 20 in FIGS. 4 and 5 has a base material layer 21 and a sealant layer 25, and has a heat-generating printed layer 26 in a portion between the base material layer 21 and the sealant layer 25. Furthermore, the lid material 20 shown in FIGS. 4 and 5 has a pattern layer 23.

-Base material layer-
The embodiment of the base material layer of the lid material of Embodiment B is the same as the embodiment of the base material layer of the lid material of Embodiment A. Further, a preferred embodiment of the base material layer of the lid material of Embodiment B is the same as a preferred embodiment of the base material layer of the lid material of Embodiment A. In addition, the embodiment of the base material layer is, for example, the material constituting the base material layer, the layer structure of the base material layer, the thickness of the base material layer, the basis weight of the base material layer, the optical properties of the base material layer, etc. .

-Sealant layer-
The sealant layer 25 is partially heated by a seal head or the like, so that it comes into close contact with at least a portion of the flange 12 to form a heat seal area H, and has the role of sealing the opening of the container body.
The sealant layer 25 may be a single layer of a sealing layer, but is preferably composed of a laminate of a core layer and a sealing layer. The core layer contacts the base layer and the seal layer contacts the flange.

(Seal layer)
The sealing layer is partially heated by a sealing head or the like to form a heat-sealed region by coming into close contact with at least a portion of the flange. For this reason, it is preferable that the sealing layer is made of a thermoplastic resin having heat-sealing properties.

Moreover, it is preferable that the sealing layer has easy-peel properties so that it can be easily peeled off from the container body.
Examples of the mechanism that imparts easy peelability include an interfacial peeling mechanism, an interlayer peeling mechanism, and a cohesive peeling mechanism. Among these, in Embodiment B in which the container body is made of paper, the cohesive and peeling mechanism is preferable. The peeling principle of the cohesive peeling mechanism utilizes the small cohesive force of immiscible or partially compatible layers. This is thought to be due to cohesive failure of the sealing layer of the dissolved or partially compatible sealing layer.

Combinations of materials exhibiting a cohesive failure mechanism include combinations of polyolefin and polystyrene, combinations of polyethylene and polypropylene, and combinations of low density polyethylene and polybutene-1. Among these, a combination of low density polyethylene and polybutene-1 is preferred.

In the combination of low density polyethylene and polybutene-1, the mass ratio of low density polyethylene and polybutene-1 is preferably 55:45 to 80:20, and preferably 55:45 to 75:25. More preferred. By setting the mass ratio within the above range, easy peelability can be easily improved.
The low-density polyethylene is preferably high-pressure low-density polyethylene with a melting point of 110° C. or lower. The low density polyethylene preferably has an MFR of 0.5 to 50.
Further, polybutene-1 is preferably a homopolymer having a melting point of 120° C. or higher. The polybutene-1 preferably has an MFR of 0.2 to 20.

(core layer)
Preferably, the core layer is made of thermoplastic resin.
The thermoplastic resin for the core layer includes ethylene-acrylic acid copolymer resin, ethylene-methacrylic acid copolymer resin, ethylene-acrylic acid-acrylic acid ester terpolymer resin, and ethylene-methacrylic acid-acrylic acid ester. Terpolymer resin, ethylene-acrylic acid-methacrylic ester terpolymer resin, ethylene-methacrylic acid-methacrylic ester terpolymer resin, ethylene-acrylic ester-acid anhydride (maleic anhydride) etc.) terpolymer resins, ethylene-methacrylic acid ester-acid anhydride (maleic anhydride, etc.) terpolymer resins, and low-density polyethylene.

The thickness of the sealant layer can be appropriately determined from the viewpoint of easy peelability, and its range is, for example, about 1 to 100 μm.

When the sealant layer is composed of a seal layer and a core layer, the thickness ratio between the two can be adjusted as appropriate depending on the purpose. For example, when suppressing curling is important, it is preferable that the thickness of the seal layer ≦ the thickness of the core layer. Moreover, from the viewpoint of suppressing the resin of the core layer from being exposed on the surface of the seal layer, it is preferable that the thickness of the core layer≦the thickness of the seal layer.
The thickness of the sealing layer is preferably 5 to 50 μm, more preferably 5 to 30 μm, and even more preferably 5 to 15 μm.
The thickness of the core layer is preferably 5 to 50 μm, more preferably 7 to 40 μm, and even more preferably 10 to 30 μm.

The sealant layer can be formed, for example, by coextruding the sealing layer and the core layer. Alternatively, it can be formed by melt-extruding a sealing layer onto a film that will become a core layer. Note that, in order to suppress shrinkage during heat sealing, it is preferable that the obtained sealant layer is not subjected to stretching treatment.

-Heat-generating printing layer-
The embodiment of the heat-generating printed layer of the lid material of Embodiment B is the same as the embodiment of the heat-generating printed layer of the lid material of Embodiment A, unless otherwise specified. Further, a preferred embodiment of the heat-generating printed layer of the lid material of Embodiment B is the same as a preferred embodiment of the heat-generating printed layer of the lid material of Embodiment A, unless otherwise specified. Note that the embodiment of the heat-generating print layer includes, for example, the material constituting the heat-generating print layer, the area of the layer, the thickness of the layer, the width of the layer, the length of the layer, the planar shape of the layer, and the shape of the layer in plan view. The resistance value of the layer, etc.

It is preferable that D1, which is the extending direction of the heat-generating printed layer from the outside to the inside when the lidded container is viewed from above, and D2, which is the direction perpendicular to the tangent to the inner peripheral edge of the flange, are substantially parallel.
By making D1 and D2 substantially parallel, the lid material can be easily peeled and steamed. Note that "substantially parallel" means that the angle formed by D1 and D2 is 5 degrees or less, preferably 3 degrees or less, more preferably 2 degrees or less, and still more preferably 1 degree or less.

The lidded container of Embodiment B of the present invention is required to have a heat-generating printed layer in the following regions 1B and 2B when the lidded container is viewed from above.
<Area 1B>
A region connecting a circumferential portion of the outer circumferential edge of the heat-sealing region to a circumferential portion of the inner circumferential edge of the flange.
<Area 2B>
A region continuous from the region 1B and located inside the inner peripheral edge of the flange.

In order to peel and vaporize a container with a lid using the heat-generating print layer, it is considered that the heat-generating print layer should be formed only in the area corresponding to the heat seal area where the peel-steam is desired. However, if the heat-generating print layer is formed only in the area corresponding to the heat-sealing area, the lid material may not peel off at the location where the heat-generating print layer is located, and it may not be possible to prevent the flange of the paper container body from becoming too hot. There wasn't.
The container with a lid of Embodiment B of the present invention has heat-generating printed layers in regions 1B and 2B when the container with a lid is viewed from above, thereby increasing the reliability of peeling and vaporization, and preventing the flange from becoming too hot. It is possible to suppress this.

Having the heat-generating printed layer in the area 1B means that even if the inner circumferential edge H1 of the heat-sealing area does not reach the inner circumferential edge 12a of the flange, the heat-generating printed layer extends from the outer circumferential edge H2 of the heat-sealing area to the inner circumferential edge 12a of the flange. It means to have.
In FIG. 12, the area designated by the symbol i among the areas 26a having the heat-generating print layer corresponds to the area 1B.
In this way, since the region 1B reaches the inner circumferential edge 12a of the flange, it is possible to provide the first opportunity to increase the reliability of peeling and vaporization.

However, even if the region 1B has a heat-generating print layer, it is difficult to secure the area of the heat-generating print layer, and therefore the reliability of peeling and vaporization cannot be sufficiently increased. In particular, in the case of a container body made of paper as in Embodiment B, microwaves from a microwave oven are absorbed by the container body, and the amount of microwaves absorbed by the heat-generating print layer decreases, which tends to make peeling and steaming difficult. It is easier to secure the area by increasing the length of the heat-generating printed layer, but in that case, the pressure inside the container body is suddenly released to the outside after peeling and steaming, making it impossible to cook properly. For this reason, it is important to have a heat-generating print layer in the region 2B.
Region 2B is a region continuous from region 1B, and is a region inside the inner peripheral edge 12a of the flange. In FIG. 12, the area designated by reference numeral ii of the area 26a having the heat-generating print layer corresponds to area 2B.
Region 2B needs to be continuous from region 1B. This is because if the region 1B and the region 2B are not continuous, the area of the heat-generating print layer will not be increased.
As described above, by having the heat-generating printed layer in the regions 1B and 2B, the area of the heat-generating printed layer can be increased, so that the temperature of the heat-generating printed layer can be easily raised when heating in a microwave oven. , it is possible to increase the reliability of vaporization by partially peeling off the lid material.

The width W2 of the heat-generating printed layer in region 2B is preferably 1 to 15 mm, more preferably 2 to 10 mm.
By setting W2 to 1 mm or more, it is possible to easily increase the certainty that the lid material is partially peeled off and vaporized. Furthermore, by setting W2 to 15 mm or less, it is possible to easily prevent the heat-generating print layer from becoming unnecessarily high-temperature.
Note that the width of the heat-generating print layer in region 2B is the width shown by W2 in FIG. 12.

In the lidded container of Embodiment B of the present invention, the outer peripheral edge of the heat sealing area is located inside the lidded container than the outer peripheral edge of the flange, and when the lidded container is viewed from above, It is preferable that the heat generating printed layer is further provided in the following region 3B.
<Area 3B>
A region that is continuous from the region 1B and extends from the outer periphery of the heat seal region to the outer periphery of the flange.

As mentioned above, the paper container body absorbs microwaves from a microwave oven, and the heat-generating printed layer disposed in the heat seal area absorbs less microwaves. However, relatively little microwave absorption occurs near the outer peripheral edge of the flange of the container body. Therefore, by forming the heat-generating print layer on the outer peripheral edge of the flange, the microwave absorption efficiency of the heat-generating print layer can be increased.
From the above, by providing the heat-generating printed layer in the region 3B, the lid material can be partially peeled off and vaporized easily. In FIG. 12, the area indicated by reference numeral iii of the area 26a having the heat-generating print layer corresponds to area 3B.
Note that when the outer circumferential edge of the flange and the outer circumferential edge of the heat-sealed area match, the area 3B is included in the range of the area 1B.

In the container with a lid of Embodiment B of the present invention, the lid material protrudes outward from the outer peripheral edge of the flange, and when the container with a lid is viewed from above, the heat-generating printed layer is further provided in the following region 4B. It is preferable.
<Area 4B>
A region continuous from the region 1B and outside the outer peripheral edge of the flange.

The region outside the outer peripheral edge of the flange is hardly affected by microwave absorption by the paper container body, and can absorb a large amount of microwaves. Therefore, by having the heat-generating print layer in the region 4B, the temperature of the heat-generating print layer can be easily raised during heating in a microwave oven, and the lid material can be partially peeled off to facilitate steaming. In FIG. 12, the area indicated by reference numeral iv in the area 26a having the heat-generating print layer corresponds to the area 4B.

The heat-generating printed layer in the region 4B may be formed to reach the outer periphery of the lid material as shown in FIG. 9, or may be formed inside the outer periphery of the lid material as shown in FIGS. may be formed.
As shown in FIG. 9, by forming the heat-generating printed layer in region 4B so as to reach the outer periphery of the lid material, the microwave absorption efficiency is increased and the lid material is partially peeled off and vaporized. It can make it easier to improve your sexuality.
Note that the heat-generating printed layer located in the area outside the outer peripheral edge of the flange can absorb a large amount of microwaves, but if there is an excess of the heat-generating printed layer in this area, the amount of heat generated will be excessive, and the lid material will be damaged. There is a risk that the lid material may be deformed or a through hole may be formed near the end. As shown in FIGS. 10 and 12, the above-mentioned risks can be reduced by forming the heat-generating print layer in the region 4B inside the outer peripheral edge of the lid material.

The width W4 of the heat-generating printed layer in the region 4B is preferably 0.5 to 10 mm, more preferably 1 to 5 mm.
By setting W4 to 0.5 mm or more, the lid material can be partially peeled off and steamed easily. Furthermore, by setting W4 to 10 mm or less, it is possible to easily prevent the heat-generating printed layer from becoming unnecessarily high temperature.
Note that the width of the heat-generating print layer in region 4B is the width shown by W4 in FIG. 12.

The heat-generating print layer can be formed, for example, by applying a heat-generating print layer forming ink containing a material constituting the heat-generating print layer onto the base layer or the intermediate base layer and drying it.

-Picture layer, gas barrier layer, intermediate base material layer, adhesive layer-
The lid material may have other layers such as a pattern layer, a gas barrier layer, an intermediate base material layer, and an adhesive layer.
Unless otherwise specified, the pattern layer, gas barrier layer, intermediate base material layer, and adhesive layer of the lid material of Embodiment B are the same as the pattern layer, gas barrier layer, intermediate base material layer, and adhesive layer of the lid material of Embodiment A. This is similar to the embodiment of the agent layer. In addition, unless otherwise specified, preferred embodiments of the pattern layer, gas barrier layer, intermediate base material layer, and adhesive layer of the lid material of Embodiment B are the same as those of the lid material of Embodiment A. This is similar to the preferred embodiment of the material layer and the adhesive layer.
The embodiment of the pattern layer includes, for example, the material forming the pattern layer, the position in the thickness direction of the layer, the thickness of the layer, and the formation location of the layer within the plane of the lid material. Further, the embodiment of the gas barrier layer includes, for example, the material constituting the gas barrier layer, the layer configuration of the layer, the position in the thickness direction of the layer, the thickness of the layer, and the like. Furthermore, the embodiment of the intermediate base layer includes, for example, the material that constitutes the intermediate base layer, the layer configuration of the layer, the position in the thickness direction of the layer, the thickness of the layer, and the like. Further, the embodiment of the adhesive layer includes, for example, the material forming the adhesive layer, the position in the thickness direction of the layer, the thickness of the layer, and the like.

- Layer composition of lid material -
Specific examples of the layer structure of the lid material of Embodiment B include those similar to those of the layer structure of the lid material of Embodiment A (m1 to m8 above).

《Heat seal area》
The container with a lid has a heat-sealed region in which at least a portion of the flange of the container body and a sealant layer of the lid material are heat-sealed. The heat seal area allows the lidded container to seal the contents.

Preferably, the heat-sealing region is formed continuously in a band-like or linear shape so as to go around the flange (FIGS. 6 and 8 to 11).
The area of the heat seal area may correspond to the area of the flange. In other words, the sealant layer may be heat sealed to all of the flanges. On the other hand, as shown in FIGS. 8 to 11, the sealant layer may be heat-sealed to a portion of the flange, and the area of the heat-sealed region may not match the area of the flange.

The width of the heat seal area (the distance between H1 and H2 in FIGS. 8 to 11) is preferably 10% to 90%, more preferably 20 to 80%, of the width of the flange.

"Contents"
The contents stored in the container body are not particularly limited. Note that when the contents are liquid, the liquid contents absorb microwaves from microwave ovens, so the lid material tends to be difficult to peel off and steam. However, in Embodiment B of the present invention, the contents Even if it is in liquid form, it does not interfere with the peeling and evaporation of the lid material. Therefore, it is preferable that the content is a liquid substance because the effects of Embodiment B of the present invention can be more easily exerted.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto.

<Example of Embodiment A>
[Example A1]
A-1. Preparation of lid material After corona discharge treatment is applied to one surface of the base material layer (stretched PET film with a thickness of 12 μm), a pattern layer forming ink is gravure printed and dried to form a pattern layer with a dry film thickness of 1.5 μm. was formed on the entire surface of the base layer.
Next, an ink containing a conductive polymer (manufactured by Tokyo Ink Co., Ltd., product number MW heating agent) was gravure printed on a part of the pattern layer and dried to form a heat-generating print layer with a thickness of 0.5 μm. The heat-generating printed layer was formed so that it was present in areas 1A and 2A, but not in area 3A, when the lidded container was viewed from above (see FIG. 2).
Next, an intermediate base material layer (stretched Ny, thickness 15 μm) was attached to the surface of the heat-generating ink layer by a dry lamination method using a polyurethane adhesive.
Next, a laminate was obtained in which a sealant layer was attached to the side of the intermediate base material layer opposite to the heat generating ink layer by a dry lamination method using a polyurethane adhesive. The sealant layer was a two-layer coextruded film consisting of a core layer (thickness: 27 μm) and a sealing layer (thickness: 3 μm). A sealing layer was placed on the second base layer side. A propylene-ethylene block copolymer was used for the core layer. The sealing layer was a mixture of the first resin (A) and the second resin (B). A propylene-ethylene random copolymer was used as the first resin (A). Polyethylene (B1) and olefin elastomer (B2) were used as the second resin (B). The content of the olefin elastomer (B2) in the seal layer was within the range of 2 to 10% by mass. Low-density polyethylene and high-density polyethylene were used for polyethylene (B1).
Next, the laminate obtained in the above step was cut to obtain a lid material (approximately rectangular shape of 115 mm in length and 160 mm in width) used in Example A1.
The lid material used in Example A1 consists of, from the outer layer side, a base material layer (stretched PET), a pattern layer, a heat-generating ink layer (note: the heat-generating ink layer is a part of the surface), an adhesive layer, and an intermediate base material layer ( Stretched Ny), an adhesive layer and a sealant layer.

A-2. Production of a container with a lid for microwave heating <container body>
A container body made of plastic (highly crystalline propylene homopolymer) having a flange at the opening was prepared (the average thickness of the flange (T1) was 0.5 mm, the average thickness of the part of the container body other than the flange (T2)). is 0.3 mm). The shape of the container main body in plan view was a substantially rectangular shape shown in FIG. 2, and the shape along the outer edge was 110 mm long and 150 mm wide. Further, the width of the flange was 5 mm, and the depth of the container body was 30 mm.
<Adhesion between container body and lid material>
After storing 300 g of water as contents in the container body, the lid material of Example A1 was heat-sealed under the following conditions to obtain a container with a lid for heating in a microwave oven of Example A1. As the heat sealer, a tray sealer manufactured by Shinwa Kikai Co., Ltd. was used. The width of the heat seal area (the distance between H1 and H2 in FIG. 2) was set to 3 mm. In the container with a lid of Example A1, the length of the heat-generating printed layer was 20 mm, the width W1 of region 1A was 4 mm, and the width W2 of region 2A was 10 mm.
<Heat sealing conditions of Example A1>
・Temperature: 175℃
・Time: 1.0 seconds ・Pressure: 0.5MPa (air cylinder type)

[Example A2]
A lid material and a lidded container were prepared in the same manner as in Example A1, except that when the lidded container was viewed from above, the heating print layer was formed in areas 1A, 2A, and 3A. Obtained. In the lidded container of Example A2, the length of the heat generating printed layer was 20 mm, the width W1 of region 1A was 4 mm, the width W2 of region 2A was 10 mm, and the width W3 of region 3A was 1 mm.

[Example A3]
A-1. Preparation of lid material: Gravure print the pattern layer forming ink on the entire surface of one side of the base material layer (paper base material with a basis weight of 150 g/ ^m2 ) and dry it to form a pattern layer with a dry film thickness of 1.5 μm. did.
Next, a heat-generating print layer having a thickness of 0.5 μm was formed on a part of the pattern layer using an ink containing a conductive polymer (manufactured by Tokyo Ink Co., Ltd., product number MW heating agent). The heat-generating printed layer was formed so that it was present in areas 1A and 2A, but not in area 3A, when the lidded container was viewed from above (see FIG. 2).
Next, an intermediate base layer (stretched PET, thickness 15 μm) was bonded to the opposite side of the base layer from the pattern layer while melting and extruding polyethylene. Through this process, an adhesive layer (molten polyethylene) with a thickness of 15 μm and an intermediate base material layer (stretched PET, thickness 15 μm) were formed on the opposite side of the pattern layer of the base layer.
Next, a laminate was obtained in which a sealant layer similar to that in Example A1 was attached to the side of the intermediate base material layer opposite to the adhesive layer by a dry lamination method using a polyurethane adhesive.
Next, the laminate obtained in the above step was cut to obtain a lid material (approximately rectangular shape, 115 mm long and 160 mm wide) used in Example A3.
The lid material used in Example A3 consists of, from the outer layer side, a heat-generating ink layer (note: the heat-generating ink layer is a part of the surface), a pattern layer, a base material layer (paper base material with a basis weight of 150 g/m ² ), and an adhesive. It has an agent layer, an intermediate base material layer (stretched PET), an adhesive layer, and a sealant layer.

A-2. Production of a container with a lid for heating in a microwave oven Next, a container with a lid for heating in a microwave oven of Example A3 was obtained in the same manner as in Example A1. In the lidded container of Example A3, the length of the heat-generating printed layer was 20 mm, the width W1 of region 1A was 4 mm, and the width W2 of region 2A was 10 mm.

[Comparative example A1]
Example A1 except that when the container with a lid is viewed from above, the heat-generating print layer is formed in region 1A, while the heat-generating print layer is not formed in region 2A and region 3A. A lid material and a container with a lid were obtained in the same manner. In the lidded container of Comparative Example A1, the length of the heat-generating printed layer was 20 mm, and the width W1 of region 1A was 4 mm.

A-3. Evaluation <Peeling and steaming of lid material>
Twenty samples for evaluation were prepared for each of Examples A1 to A3 and Comparative Example A1, each of which was filled with 300 ml of water in a container with a lid. Each evaluation sample was heated in a microwave oven with an output of 600 W for 120 seconds, and it was visually confirmed whether the lid material was partially peeled off and steamed, and ranked based on the following criteria.
A: The lid material of all samples was partially peeled off and steamed.
C: Out of 20 samples, even one sample was not peeled and steamed.

From the results shown in Table 1, it can be confirmed that the container with a lid for heating in a microwave oven according to Embodiment A of the present invention can increase the reliability of peeling and steaming of the lid material.

<Example of Embodiment B>
[Example B1]
B-1. Preparation of lid material After corona discharge treatment is applied to one surface of the base material layer (stretched PET film with a thickness of 12 μm), a pattern layer forming ink is gravure printed and dried to form a pattern layer with a dry film thickness of 1.5 μm. was formed on the entire surface of the base layer.
Next, an ink containing a conductive polymer (manufactured by Tokyo Ink Co., Ltd., product number MW heating agent) was gravure printed on a part of the pattern layer and dried to form a heat-generating print layer with a thickness of 0.5 μm. The heat-generating printed layer was formed so that it was present in regions 1B, 2B, and 3B, but not in region 4B, when the lidded container was viewed from above (see FIG. 8).
Next, an intermediate base material layer (stretched Ny, thickness 15 μm) was attached to the surface of the heat-generating ink layer by a dry lamination method using a polyurethane adhesive.
Next, an adhesive layer forming ink containing a polyurethane adhesive was applied to the side of the intermediate base material layer opposite to the heat generating ink layer and dried to form an adhesive layer.
Next, a two-layer sealant layer was coextruded and laminated on the adhesive layer at an extrusion temperature of 300° C. to form a sealant layer. Of the two sealant layers, the layer on the adhesive layer side is a 20 μm thick layer made of ethylene-methacrylic acid copolymer (melting point 98°C), and the layer on the side far from the adhesive layer is made of low-density polyethylene. It is a 10 μm thick layer made of a mixture (mass ratio 65:35) of polybutene-1 (melting point 105°C) and polybutene-1 (melting point 125°C).
Next, the laminate obtained in the above step was cut to obtain a lid material (approximately rectangular with a length of 160 mm and a width of 160 mm) used in Example B1.
The lid material used in Example B1 consists of, from the outer layer side, a base material layer (stretched PET), a pattern layer, a heat-generating ink layer (note: the heat-generating ink layer is a part of the surface), an adhesive layer, and an intermediate base material layer ( Stretched Ny), an adhesive layer and a sealant layer.

B-2. Production of a container with a lid for microwave heating <container body>
A paper container body having a flange at the opening was prepared.
The container body was obtained by deep drawing a member having a resin layer (polypropylene) with a thickness of 30 μm on both sides of paper with a basis weight of 350 g/m ² . Incidentally, wrinkles generated on the flange during deep drawing were smoothed by ultrasonic processing (see Japanese Patent Laid-Open No. 2000-33927).
The shape of the container main body in plan view was approximately square, and the shape along the outer edge was 150 mm long and 150 mm wide. Further, the width of the flange was 10 mm, and the depth of the container body was 40 mm.
<Adhesion between container body and lid material>
After storing 300 g of water as contents in the container body, the lid material of Example B1 was heat-sealed under the following conditions to obtain a container with a lid for heating in a microwave oven of Example B1. As the heat sealer, a tray sealer manufactured by Shinwa Kikai Co., Ltd. was used. The width of the heat seal area was 5 mm. In the container with a lid of Example B1, the length of the heat-generating printed layer was 20 mm, the width W1 of region 1B was 7.5 mm, the width W2 of region 2B was 10 mm, and the width W3 of region 3B was 2.5 mm. .
<Heat sealing conditions of Example B1>
・Temperature: 175℃
・Time: 1.0 seconds ・Pressure: 0.5MPa (air cylinder type)

[Example B2]
A lid material and a lid were prepared in the same manner as in Example B1, except that when the lidded container was viewed from above, the heating printed layer was formed in areas 1B, 2B, 3B, and 4B. A container was obtained (see FIG. 10). In the lidded container of Example B2, the length of the heat-generating print layer is 20 mm, the width W1 of region 1B is 7.5 mm, the width W2 of region 2B is 10 mm, the width W3 of region 3B is 2.5 mm, and the width of region 4B. W4 was 2 mm.

[Example B3]
B-1. Preparation of lid material: Gravure print the pattern layer forming ink on the entire surface of one side of the base material layer (paper base material with a basis weight of 150 g/ ^m2 ) and dry it to form a pattern layer with a dry film thickness of 1.5 μm. did.
Next, a heat-generating print layer having a thickness of 0.5 μm was formed on a part of the pattern layer using an ink containing a conductive polymer (manufactured by Tokyo Ink Co., Ltd., product number MW heating agent). The heat-generating printed layer was formed so that it was present in regions 1B, 2B, and 3B, but not in region 4B, when the lidded container was viewed from above (see FIG. 8).
Next, an intermediate base layer (stretched PET, thickness 15 μm) was bonded to the opposite side of the base layer from the pattern layer while melting and extruding polyethylene. Through this process, an adhesive layer (molten polyethylene) with a thickness of 20 μm and an intermediate base material layer (stretched PET, thickness 15 μm) were formed on the side of the base material layer opposite to the pattern layer.
Next, a laminate was obtained by laminating the same adhesive layer and sealant layer as in Example B1 on the side of the intermediate base material layer opposite to the adhesive layer.
Next, the laminate obtained in the above step was cut to obtain a lid material (approximately rectangular shape, 160 mm long and 160 mm wide) used in Example B3.
The lid material used in Example B3 consists of, from the outer layer side, a heat-generating ink layer (note: the heat-generating ink layer is a part of the surface), a pattern layer, a base material layer (paper base material with a basis weight of 150 g/m ² ), and an adhesive. It has an agent layer, an intermediate base material layer (stretched PET), an adhesive layer, and a sealant layer.

B-2. Production of a container with a lid for heating in a microwave oven Next, a container with a lid for heating in a microwave oven of Example B3 was obtained in the same manner as in Example B1. In addition, in the container with a lid of Example A3, the length of the heat generating printed layer is 20 mm, the width W1 of area 1B is 7.5 mm, the width W2 of area 2B is 10 mm, the width W3 of area 3B is 2.5 mm, and the width W3 of area 4B is 2.5 mm. The width W4 was 2 mm.

[Comparative example B1]
Same as Example B1, except that when the container with a lid is viewed from above, the heat-generating print layer is formed in region 1B, while the heat-generating print layer is not formed in regions 2B to 4B. A lid material and a container with a lid were obtained. In the lidded container of Comparative Example B1, the length of the heat-generating printed layer was 20 mm, and the width W1 of region 1B was 7.5 mm.

B-3. Evaluation <Peeling of lid material>
Twenty samples for evaluation were prepared for each of Examples B1 to B3 and Comparative Example B1, each of which was filled with 300 ml of water in a container with a lid. Each evaluation sample was heated for 120 seconds in a tableless microwave oven with an output of 600W.
It was visually confirmed whether or not the lid material partially peeled off and steamed, and it was ranked according to the following criteria.
A: The lid material of all samples was partially peeled off and steamed.
C: Out of 20 samples, even one sample was not peeled and steamed.

From the results shown in Table 2, it can be confirmed that the container with a lid for heating in a microwave oven according to Embodiment B of the present invention can increase the reliability of peeling and steaming of the lid material.

10 Container body 11 Opening 12 Flange 12a Inner rim of flange 12b Outer rim of flange 16 Body 17 Bottom H Heat seal area H1 Inner rim of heat seal area H2 Outer rim of heat seal area 20 Lid material 21 Base material layer 23 Pattern Layer 25 Sealant layer 26 Heat-generating printed layer 26a Area 27 having heat-generating printed layer Holding part 100 Container with lid for microwave heating

Claims (6)

A container with a lid, comprising a paper container main body having a flange at the opening and accommodating contents, and a lid material sealing the container main body,
The basis weight of the paper of the container body is 150 to 400 g/m ² ,
The lid material has a base material layer and a sealant layer, and a heat-generating printed layer on a part between the base material layer and the sealant layer or a part of the base material layer on the opposite side of the sealant layer. have,
The lidded container is sealed by a heat-sealed region in which at least a portion of the flange and the sealant layer are heat-sealed,
A container with a lid for heating in a microwave oven, which has the heat-generating printed layer in the following areas 1B and 2B when the container with a lid is viewed from above.
<Area 1B>
A region connecting a circumferential portion of the outer circumferential edge of the heat-sealing region to a circumferential portion of the inner circumferential edge of the flange.
<Area 2B>
A region continuous from the region 1B and located inside the inner peripheral edge of the flange. The container with a lid for heating in a microwave oven according to claim 1, wherein the width of the heat-generating printed layer in the region 2B is 1 to 15 mm. The outer circumferential edge of the heat-sealing area is located inside the lidded container than the outer circumferential edge of the flange, and when the lidded container is viewed from above, the heat-generating printed layer is further provided in the following area 3B. The container with a lid for heating in a microwave oven according to claim 1 or 2.
<Area 3B>
A region that is continuous from the region 1B and extends from the outer periphery of the heat seal region to the outer periphery of the flange. According to any one of claims 1 to 3, the lid material protrudes outward from the outer peripheral edge of the flange, and further has the heat-generating printed layer in the following region 4B when the lidded container is viewed from above. Container with lid for microwave heating as described.
<Area 4B>
A region continuous from the region 1B and outside the outer peripheral edge of the flange. The container with a lid for heating in a microwave oven according to claim 4, wherein the width of the heat-generating printed layer in the area 4B is 0.5 to 10 mm. D1, which is a direction in which the heat-generating printed layer extends from the outside to the inside, when the container with a lid is viewed from above, and D2, which is a direction perpendicular to a tangent to the inner peripheral edge of the flange, are substantially parallel to each other. A container with a lid for heating in a microwave oven according to any one of items 1 to 5.