JP2021066501A - Lid material for microwave oven heating container, and container provided with lid for microwave oven heating - Google Patents

Abstract

To provide a lid material for a microwave oven heating container, that is capable of enhancing reliability of peeling steam-venting by a simple method.SOLUTION: A lid material for a microwave oven comprises a substrate layer and a sealant layer, and a heat generation printing layer at a part between the substrate layer and the sealant layer, or at a part of the substrate layer on an opposite side to the sealant layer. At least part of an outer edge of an area comprising the heat generation printing layer is arranged near an outer peripheral edge of the lid material, and the following condition (1) is satisfied when a center point of the lid material is defined as X, and a midpoint of a line constituting the outer edge of the area comprising the heat generation printing layer is defined as Y. <Condition 1> Value of resistance in an XY direction of the heat generation printing layer < Value of resistance in a direction orthogonal to the XY direction of the heat generation printing layer.SELECTED DRAWING: Figure 3

Description

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

Microwave oven heating sealing containers that can be cooked in a microwave oven while containing food and other contents are commercially available. When these sealed containers for heating in a microwave oven are cooked using a microwave oven, the internal pressure inside the container increases, and the container deforms or bursts. Therefore, 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 portion and an outer seal portion, and a non-seal portion is provided between the inner seal portion and the outer seal portion. Further, a part of the inner seal portion is provided. A V-shaped projecting portion is formed so as to project inward, and a ventilation portion for communicating the outside air and the non-sealing portion is formed in a part of the outer sealing portion.

When the packaging container having the configuration of Patent Document 1 is heated in a microwave oven, steam is generated in the main body due to the heating and the internal pressure rises. At this time, the peeling region on the flange portion of the sealing film tends to expand concentrically, and a force for peeling is applied to the sealing film on the protruding portion from the radial direction and the circumferential direction. As a result, the protruding portion is peeled off earlier than the other portions, and the steam is exhausted through the steaming portion. Therefore, it is possible to prevent the contents from being scattered due to the rupture of the packaging container due to the 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 according to the shapes of the inner seal portion and the outer seal portion, and there is a problem that the cost of the packaging container increases.
As a solution to such a problem, a packaging container of Patent Document 2 has been proposed.

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

The packaging container of Patent Document 2 has a printed portion in which an ink containing a conductive polymer is arranged between a base material layer of a sealing film (lid material) and a heat-adhesive layer, and a non-printed portion in which the ink is not arranged. It is provided, and a ventilation hole is formed by causing peeling of the sealing film or penetration of the sealing film by softening the heat-adhesive layer at a portion having a printed portion in the surface of the packaging container. It emits steam.

However, while the packaging container of Patent Document 2 may succeed in peeling and steaming, it often fails in peeling and steaming, and it cannot be said that the certainty of peeling and steaming is sufficient. there were.

As a result of diligent research, the present inventors may have anisotropy in the resistance value of the heat-generating printing layer, and by arranging the heat-generating printing layer in the plane of the lid material in consideration of the anisotropy, The present invention has been completed by finding that the certainty of peeling and steaming can be enhanced.

That is, the present invention provides the following [1] to [3].
[1] A lid material having a base material layer and a sealant layer, and heat-generating printing is performed on a part between the base material layer and the sealant layer or a part of the base material layer on the side opposite to the sealant layer. When a region having a layer and having a heat-generating printing layer in the plane of the lid material is defined as a heat-generating region, at least a part of the outer peripheral edge of the heat-generating region is arranged in the vicinity of the outer peripheral edge of the lid material. A lid material for a microwave heating container that satisfies the following condition (1) when the central point of the lid material is defined as X and the middle point of the line forming the outer peripheral edge of the heat generating region is defined as Y.
<Condition 1>
Resistance value in the XY direction of the heat-generating printing layer <Resistance value in the direction orthogonal to the XY direction of the heat-generating printing layer [2] The resistance value of the heat-generating printing layer in the XY direction is 1.5 kΩ or more and 100 kΩ or less [1] ] The lid material for the microwave heating container described in.
[3] A container with a lid having a flange at the opening and provided with a paper container body for accommodating the contents and a lid material for sealing the container body, wherein the lid material is [1]. Alternatively, a container with a lid for heating a microwave oven, which is the lid material according to [2] and has a heat-sealed region in which at least a part of the flange and the sealant layer of the lid material are heat-sealed.

The lid material for the microwave oven heating container of the present invention and the container with a lid for microwave oven heating can enhance the certainty of peeling and steaming.

It is sectional drawing which shows one Embodiment of the lid material of this invention. It is sectional drawing which shows the other embodiment of the lid material of this invention. It is a top view which the lid material of FIG. 1 was visually recognized from the base material layer side. It is a top view which shows the embodiment of the pattern of the heat generation printing layer. It is a perspective view which shows the embodiment of the container with a lid for heating a microwave oven of this invention.

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

[Lid material for microwave oven heating container]
The lid material for the microwave heating container of the present invention is a lid material having a base material layer and a sealant layer, and is a part between the base material layer and the sealant layer or the sealant layer of the base material layer. When a heat-generating printing layer is provided on a part opposite to the heat-generating region and a region having the heat-generating printing layer in the surface of the lid material is defined as a heat-generating region, at least a part of the outer peripheral edge of the heat-generating region is the lid. It is arranged near the outer peripheral edge of the material, and when the central point of the lid material is defined as X and the middle point of the line forming the outer peripheral edge of the heat generating region is defined as Y, the following condition (1) is satisfied. is there.
<Condition 1>
The resistance value of the heat-generating printing layer in the XY direction <the resistance value of the heat-generating printing layer in the direction orthogonal to the XY direction.

In the present specification, the "lid material for a microwave oven heating container" may be referred to as a "lid material", and the "lid container for a microwave oven heating container" may be referred to as a "lid container".

1 and 2 are cross-sectional views showing an embodiment of the lid material 20 of the present invention.
The lid material 20 of FIGS. 1 and 2 has a base material layer 21 and a sealant layer 25, and has a heat-generating printing layer 26 in a part between the base material layer 21 and the sealant layer 25. In FIGS. 1 and 2, reference numeral 26a indicates a region having a heat-generating print layer (heat-generating region), and reference numeral 26b indicates a region having no heat-generating printing layer. Further, the lid material 20 of FIGS. 1 and 2 has a pattern layer 23.

FIG. 3 is a plan view of the lid material 30 of FIG. 1 as viewed from the base material layer 21 side, and is a view showing a heat generating region 26a in the plan view. In FIG. 3, reference numeral X indicates the center of the lid material, and reference numeral Y indicates the midpoint of the line forming the outer peripheral edge of the heat generating region. In FIG. 3, the outer peripheral edge 20i of the lid material is indicated by a broken line in order to make it easier to compare the outer peripheral edge 20i of the lid material with the outer peripheral edge 26i of the heat generating region. Further, in FIG. 3, reference numeral 26ii indicates an inner peripheral edge of the heat generating region, and reference numeral 26iii indicates a side peripheral edge of the heat generating region.

<Base layer>
The base material layer is preferably one or more selected from a plastic film and a paper base material.
The plastic film is preferable in that the gas barrier property is relatively good, and the paper base material is preferable in that the dead hold property (the property of being able to maintain a deformed state such as bending and twisting) is relatively good.

The base material layer 21 may be only a single layer as shown in FIGS. 1 and 2, but may have a multi-layer structure in which two or more plastic films and / or paper base materials are adhered to each other. When the base material layer contains two or more plastic films and / or paper base materials, a plurality of the same type may be contained, or different types may be contained.

From the viewpoint of heat resistance, it is preferable to use one or more of a polyester film such as polyethylene terephthalate and a polyamide film such as nylon as the base material layer plastic film. Since nylon has excellent piercing strength, it is preferable because it is easy to prevent the lid material from being torn when filling solid contents or when stacking containers.
Further, 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 by itself can be used in combination. For example, by using at least one of a polyester film and a polyamide film together with a plastic film having excellent gas barrier properties such as an ethylene-vinyl alcohol copolymer resin film and a polyvinylidene chloride film, the heat resistance and gas barrier properties of the entire laminate can be obtained. Can be improved.

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 plastic film preferably has a total light transmittance of JIS K7361-1: 1997 of 85% or more, and more preferably 90% or more. The haze of JIS K7136: 2000 is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less in the plastic film.
By setting the total light transmittance and the haze within the above ranges, these layers can be easily visually recognized when the pattern layer and / or the heat-generating printing layer is formed on the inner layer side of the plastic film.

<Sealant layer>
The sealant layer is partially heated by a seal head or the like to form a heat-sealing region in close contact with at least a part of the flange of the container body, and has a role of sealing the opening of the container body.

The sealant layer may be a single layer of the seal layer, but is preferably composed of a laminate of the core layer and the seal layer.
The core layer is a layer that comes into contact with the base material layer, and it is preferable that the core layer has good adhesion to the base material layer and the seal layer.
The seal layer is a layer that comes into contact with the flange, and preferably has an easy peel property that can be easily peeled off from the container body. In addition, in this specification, "good easy peeling property" does not simply mean that the peeling strength is weak, and the peeling strength at the time of peeling is too strong while having an adhesive strength enough to guarantee the sealing property. It means that there is nothing.
Examples of the mechanism for imparting the easy peeling property include an interface peeling mechanism, an delamination mechanism, and a cohesive peeling mechanism, and any mechanism can be adopted. The peeling principle in the cohesive peeling mechanism utilizes the fact that the cohesive force of the incompatible or partially compatible layer is small, and at the time of opening, it is not the interface between the seal layer and the adherend (flange of the container body), but the interface between the seal layer and the adherend (flange of the container body). It is considered that this is due to the cohesive failure of the seal layer of the incompatible system or the partially compatible system.

For the core layer and the seal layer, a general-purpose material of the sealant layer can be used. For the core layer and the seal layer, it is preferable to select appropriate materials according to the material (paper, plastic, etc.) of the container body to be applied.

The sealant layer can be formed, for example, by coextruding the seal layer and the core layer. Alternatively, it can be formed by melt-extruding a seal layer onto a film to be a core layer. It is preferable that the sealant layer is not stretched in order to suppress shrinkage during heat sealing.

<< Sealant layer for lid of paper container >>
When the container body is paper, the core layer and the seal layer include the following embodiments. In addition, the following embodiment is an embodiment in which the seal layer is coagulated and broken.

-Seal layer-
The seal layer is preferably composed of a thermoplastic resin having a heat-sealing property.
Examples of the combination of materials having a coagulation fracture mechanism include a combination of polyolefin and polystyrene, a combination of polyethylene and polypropylene, a combination of low-density polyethylene and polybutene-1, and the like. Among these, a combination of low-density polyethylene and polybutene-1 is preferable.

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, preferably 55:45 to 75:25. More preferred. By setting the mass ratio within the above range, it is possible to easily improve the easy peeling property.
The low-density polyethylene is preferably a high-pressure low-density polyethylene having 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-
The core layer is preferably made of a thermoplastic resin.
Examples of the thermoplastic resin in the core layer include ethylene-acrylic acid copolymer resin, ethylene-methacrylic acid copolymer resin, ethylene-acrylic acid-acrylic acid ester ternary copolymer resin, and ethylene-methacrylic acid-acrylic acid ester. Three-way copolymer resin, ethylene-acrylic acid-methacrylic acid ester ternary copolymer resin, ethylene-methacrylic acid-methacrylic acid ester ternary copolymer resin, ethylene-acrylic acid ester-acid anhydride (maleic anhydride) Etc.) One or more selected from a ternary copolymer resin, an ethylene-methacrylic acid ester-acid anhydride (maleic anhydride, etc.) ternary copolymer resin and a low-density polyethylene can be mentioned.

The thickness of the sealant layer can be appropriately determined from the viewpoint of easy peelability, and the range thereof 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 of the two can be appropriately adjusted according to the purpose. For example, when the suppression of curl is emphasized, it is preferable that the thickness of the seal layer ≤ the thickness of the core layer. Further, 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 seal 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.

<< Sealant layer for lid of plastic container >>
When the container body is made of plastic, the core layer and the seal layer preferably have the following embodiments.

-Seal layer-
The seal layer is preferably composed of a thermoplastic resin having a heat-sealing property.
Further, the seal layer has a first resin having good adhesion to the resin constituting the flange and a first resin having good adhesion to the resin constituting the flange, and is incompatible with the first resin. It is preferably formed by mixing with the resin of 2.
Such a resin cannot be unconditionally stated because it differs depending on the type of resin constituting the flange, but when the resin constituting the flange is polypropylene resin, polypropylene is used as the first resin, and polyethylene and the second resin are used. It is preferable to use one or more selected from olefin-based elastomers. That is, when the resin constituting the flange is polypropylene, the seal layer may be formed from a mixed resin of polypropylene, which is the first resin, and one or more selected from polyethylene, which is the second resin, and an olefin-based elastomer. preferable. The second resin preferably contains polyethylene from the viewpoint of transparency, and is particularly preferably further contains an olefin elastomer from the viewpoint of impact resistance and puncture resistance after heating in a microwave oven.

Examples of the polypropylene (A) as the first resin include a propylene homopolymer, a propylene-ethylene block copolymer, and a propylene-ethylene random copolymer. Among these, a propylene-ethylene block copolymer having excellent impact resistance is preferable.
The ratio of the propylene component to the ethylene component in the propylene-ethylene random copolymer is preferably 60:40 to 99: 1, and more preferably 70:30 to 98: 2.

Examples of the propylene-ethylene block copolymer include a method of polymerizing propylene and ethylene as raw materials in the presence of a catalyst. Examples of the catalyst include a Ziegler-Natta catalyst and a 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).

The low density polyethylene is polyethylene having a density of 0.910 to 0.925 g / cm ³ . The medium density polyethylene is polyethylene having a density of 0.926 to 0.940 g / cm ³ . The high-density polyethylene is polyethylene having a density of 0.941 to 0.965 g / cm ³ .
Low-density polyethylene can be 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 pressure or low pressure of 1 atm or more and less than 1000 atm.
The linear low density polyethylene is obtained by copolymerizing an α-olefin with a linear polymer obtained by polymerizing ethylene at medium pressure or low pressure to introduce a short chain branch. 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 .

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

Examples of the olefin-based elastomer (B2) include hydrogenated styrene-based elastomers and ethylene-α-olefin elastomers.
The hydrogenated styrene-based elastomer has a structure composed 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, and is, for example, an ethylene-propylene random copolymer, an ethylene-butene random copolymer, or an ethylene-. Examples thereof include a propylene-butene random copolymer.

It is preferable that the seal layer contains an olefin elastomer (B2) because it is easy to improve the adhesion with the core layer. Further, it is preferable that the seal layer contains the olefin elastomer (B2) because it is easy to improve the puncture resistance and the impact resistance of the lid material.
When the seal layer contains an olefin elastomer (B2), the seal layer tends to soften when heated in a microwave oven. The content of the olefin-based elastomer in the seal layer is to prevent the seal layer from being softened by heating in a microwave oven and causing a sticky feeling at the time of peeling or spoiling the aesthetic appearance such as stretching into a thread. Is preferably 2 to 10% by mass. For example, when the seal layer contains polypropylene (A), polyethylene (B1) and an olefin elastomer (B2), the ratio of each component is "polypropylene (A) ≥ polyethylene (B1) ≥ olefin elastomer (B2) (mass). %) ”Is satisfied. Specifically, the seal layer is preferably 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 configuration in which the second resin (B) is arranged in an island shape in the sea of the polypropylene (A) in the seal layer. By adopting the sea-island structure of polypropylene (A) and the second resin (B) in this way, it is easy to adjust the peel strength that can impart automatic permeability and easy peeling property while ensuring initial adhesion. it can.

The thickness of the seal 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. The thickness of the sealant layer (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 with respect to the thickness of the sealant layer is more preferably 0.5 to 20%.

-Core layer-
From the viewpoint of adhesion to the seal layer, the core layer is preferably a polypropylene resin. Examples of the polypropylene-based resin include polypropylene homopolymers, propylene-ethylene block copolymers, and propylene-ethylene random copolymers. In particular, a propylene-ethylene block copolymer having an excellent balance of impact resistance and rigidity is preferable. 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.

The propylene-ethylene block copolymer has higher rigidity and softening point than the propylene-ethylene random copolymer. Therefore, as compared with the propylene-ethylene random copolymer, when the lid material is peeled off from the container after heating in a microwave oven, an appropriate rigidity can be maintained, and the interface between the seal layer and the flange in the heat seal region can be maintained. The force of peeling is easily transmitted. That is, by using the propylene-ethylene block copolymer as the core layer, the peelability can be easily improved, and the effect that the peeled surface is aesthetically pleasing can also be obtained. In particular, when the seal layer contains an olefin elastomer as described later, the seal layer is softened by heating in a microwave oven. Therefore, by using a propylene-ethylene block copolymer as a highly rigid core layer, pulling is performed. It can make it easier to convey the peeling force.

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

The heat-generating printing layer absorbs microwaves from a microwave oven and generates heat. Therefore, when the container with a lid is heated in a microwave oven, a part of the heat-sealed region of the container with a lid is peeled off by the heat generated in the heat-generating printing layer and can be vaporized. Such steaming may be referred to as "automatic steaming".

In the lid material of the present invention, when the region having the heat generation printing layer in the surface of the lid material is defined as the heat generation region, at least a part of the outer peripheral edge of the heat generation region is arranged in the vicinity of the outer peripheral edge of the lid material. When the central point of the lid material is defined as X and the middle point of the line forming the outer peripheral edge of the heat generating region is defined as Y, it is necessary to satisfy the following condition (1).
<Condition 1>
Resistance value of the heat-generating printing layer in the XY direction <Resistance value of the heat-generating printing layer in the direction orthogonal to the XY direction

The "XY direction in the plane of the lid material", which is the reference of the direction of the condition 1, means the ideal direction of peeling and steaming.
Condition 1 defines that the resistance value of the heat-generating printing layer in the XY direction is smaller than the resistance value of the heat-generating printing layer in the direction orthogonal to the XY direction. Although the detailed cause is unknown, the resistance value of the heat-generating printing layer in the XY direction is made smaller than the resistance value of the heat-generating printing layer in the direction orthogonal to the XY direction to increase the certainty of peeling and steaming. Can be done.

The heat-generating printing layer can be formed by applying an ink for forming a heat-generating printing layer on the support while transporting a support such as a base material layer in the flow direction (MD direction) and drying the support. When the heat-generating printing layer forming ink is applied onto the support in this way, the conductive components contained in the ink are oriented in the flow direction (MD direction). Therefore, it is considered that the resistance value in the flow direction (MD direction) becomes low, while the resistance value in the width direction (TD direction) becomes high, and anisotropy of the resistance value occurs.
In the lid material of the present invention, the lid material is formed so as to satisfy the condition 1 on the premise that the above-mentioned anisotropy of the resistance value occurs. For example, a lid material satisfying condition 1 can be obtained by determining the shape of the pattern of the heat-generating ink layer and the punching direction in consideration of the orientation of the conductive component in the MD direction.

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

In the lid material of the present invention, the ratio of the resistance value of the heat-generating printing layer in the XY direction to the resistance value in the direction orthogonal to the XY direction of the heat-generating printing layer (the resistance value of the heat-generating printing layer in the XY direction / the XY direction of the heat-generating printing layer). The resistance value in the orthogonal direction) is preferably 0.70 to 0.95, more preferably 0.80 to 0.93.

The resistance value of the heat-generating printing 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, and further preferably 2.0 kΩ or more and 30 kΩ or less. It is even more preferable that it 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 printing layer and to easily suppress problems such as through-holes in the lid material. Further, by setting the resistance value to 100 kΩ or less, the heat-generating printing layer can generate heat appropriately and can be easily peeled and vaporized.

In the present specification, "near the outer peripheral edge of the lid material" means a region within 3 mm from the outer peripheral edge of the lid material. That is, at least a part of the outer peripheral edge of the heat generating region is in contact with the outer peripheral edge of the lid material, or if not in contact, is located in a region within 3 mm from the outer peripheral edge of the lid material.
When at least a part of the outer peripheral edge of the heat generating region is in contact with the outer peripheral edge of the lid material, the microwave absorption efficiency can be improved, and the certainty that the lid material is partially peeled off and steamed can be easily increased. It is preferable in that. In particular, when the container body is made of paper or when the contents contained in the container are liquid, the microwave absorption efficiency of the heat-generating printing layer tends to decrease, but the closer to the outer peripheral edge of the lid material, the lower the efficiency. The microwave absorption efficiency of the heat-generating printing layer is less likely to decrease. Therefore, by adopting a configuration in which at least a part of the outer peripheral edge of the heat generating region is in contact with the outer peripheral edge of the lid material, the microwave absorption efficiency is improved, and the certainty that the lid material is partially peeled off and steamed is improved. It can be done easily.
Further, from the viewpoint of improving peeling and ventilation, the midpoint of the line forming the outer peripheral edge of the heat generating region is preferably located near the outer peripheral edge of the lid material.

Area of the heat generating print layer is preferably 1 cm ² or more, more preferably 1～12Cm ^2, further preferably 3~8cm ^2.
By setting the area of the heat-generating printing layer to 1 cm ² or more, it is possible to easily apply the amount of heat generated for peeling and steaming. Further, by setting the area of the heat-generating printing layer to 12 cm ² or less, it is possible to prevent the area for peeling and steaming from becoming excessive, which hinders the degree of cooking of the contents.

The thickness of the heat-generating printing layer is preferably 0.1 to 5 μm, more preferably 0.2 to 3 μm.
By setting the thickness of the heat-generating printing layer to 0.1 μm or more, it is possible to easily apply the amount of heat generated for peeling and steaming. Further, by setting the thickness of the heat-generating printing layer to 5 μm or less, it is possible to prevent the heat-generating printing layer from becoming unnecessarily high in temperature, and to prevent the lid material from being deformed or having through holes in the lid material. It can be done easily.

When the length on the outer peripheral side of the heat-generating printing layer is defined as L1 and the length on the inner peripheral side is defined as L2, L1 and L2 are preferably 15 to 50 mm, respectively, and more preferably 15 to 40 mm. ..

The pattern of the heat-generating printing layer in the surface of the lid material is not particularly limited. Examples of the pattern of the heat-generating printing layer include the patterns shown in FIGS. 3 and 4 (a) to 4 (f).

When the length of the line forming the outer peripheral edge of the heat-generating printing layer is defined as L1 and the length of the line forming the inner peripheral edge of the heat-generating printing layer is defined as L2, it is preferable to satisfy the relationship of L1 <L2. When the upper outer peripheral side and the lower side of FIG. 4 are the inner peripheral side, (d) to (f) of FIG. 4 satisfy the relationship. Since the pressure in the container is transmitted concentrically, the efficiency of peeling and steaming can be improved by satisfying the relationship.
Further, it is more preferable that the heat-generating printing layer satisfying the relationship of L1 <L2 satisfies the relationship that the length continuously decreases from the outer peripheral side to the inner peripheral side. When the upper outer peripheral side and the lower side of FIG. 4 are the inner peripheral side, (e) and (f) of FIG. 4 satisfy the relationship.
Further, among those satisfying the above relationship, those in which both ends on the outer peripheral side and both ends on the inner peripheral side are connected by a curve are preferable. FIG. 4 (f) satisfies the relationship. By having such a configuration, the pressure in the container can be transmitted more efficiently, and the certainty of ventilation can be further improved.

L1 / L2 is preferably 0.30 to 0.90, more preferably 0.50 to 0.80, and even more preferably 0.60 to 0.70.

When the midpoint of the line forming the inner peripheral edge of the heat-generating printing layer is defined as Z, the X (center point of the lid material) and the Y (midpoint of the line forming the outer peripheral edge of the heat-generating region) are defined as Z. It is preferable that the connecting line and the line connecting Z and Y are substantially parallel. By satisfying this relationship, the efficiency of peeling and steaming can be improved. In addition, substantially parallel means within 0 degree ± 3 degree, preferably within 0 degree ± 2 degree, more preferably within 0 degree ± 1 degree.

The heat-generating printing layer is a layer that absorbs microwaves to generate heat, and includes a material that absorbs microwaves.
Examples of the material that absorbs microwaves include conductive particles and a conductive polymer. Among these, the conductive polymer is suitable because it has good transparency of visible light and is less likely to generate 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 preferable. Further, when a conductive polymer is used, it is more preferable to further contain 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, dyes, Included are alkylammonium ions and quaternary phosphonium salts.

When conductive particles are used as the conductive agent, the heat-generating printing layer preferably contains a binder resin. Further, when a conductive polymer is used as the conductive agent, another resin may be contained in order to adjust the conductivity.

Binder resins used together with conductive particles and resins used together with conductive polymers include polyolefin resins such as polyethylene resins and chlorinated polypropylene resins, poly (meth) acrylic resins, polyvinyl chloride resins, and poly. 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, phenol resin, xylene Fiber-based resins, maleic acid resins, fibrous resins such as nitrocellulose and ethylcellulose, acetylbutylcellulose and ethyloxyethylcellulose, rubber-based resins such as rubber chloride and cyclized rubber, petroleum-based resins, natural resins such as rosin and casein Can be mentioned.

The heat-generating printing layer further comprises, if necessary, for example, colorants, fillers, stabilizers, plasticizers, antioxidants, UV absorbers, light stabilizers, dispersants, thickeners, desiccants, lubricants and Any additive such as a cross-linking agent can be added. Among these additives, a colorant is preferable. That is, the heat-generating printing layer preferably contains a colorant.

<Pattern layer>
The lid material of the present invention may have a pattern layer.
The position of the pattern layer may be appropriately determined in consideration of the light transmission of the base material layer and the heat-generating printing layer.

For example, when a base material layer having low light transmission such as paper or an opaque plastic film is provided, the pattern layer is preferably arranged on the outer layer side of the base material layer having low light transmission. Further, when a base material layer having high light transmission such as a transparent plastic film is provided, it is preferable to arrange the pattern layer on the inner layer side of the base material layer having high light transmission from the viewpoint of protecting the pattern layer. Further, when a plurality of base material layers are provided, the position of the pattern layer may be appropriately determined in consideration of the light transmittance of each base material layer and the like.
In FIGS. 1 and 2, the pattern layer 23 is arranged on the inner layer side of the base material layer 21. In this case, the base material layer 21 is preferably a base material layer having high light transmission.

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

The pattern layer can form a pattern by one or more combinations selected from characters, figures, symbols, patterns, patterns, solid printing, and the like. The pattern layer is not limited to a single layer, and may be a plurality of layers of two or more layers.
The pattern layer 23 may be formed on the entire surface of the lid material as shown in FIGS. 1 and 2, or may be formed on a part of the surface of the lid material.

The pattern layer mainly contains a colorant and a binder resin.
Colorants 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, petals and cadmium. Colored inorganic pigments such as red, ultramarine blue and cobalt blue; chromatic organic pigments such as quinacridone red, isoindolinone yellow and phthalocyanine blue; brilliant materials such as pearl pigments and metal scales; dyes and the like. Species or two or more species can be used.
Examples of the binder resin include those similar to the binder resin exemplified in the heat-generating printing layer.

The content of the colorant in the pattern layer is not particularly limited, but 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. It is more preferably ~ 60% by mass.

When a bright pigment is contained as the colorant, the pearl pigment is preferable as the bright pigment from the viewpoint of microwave oven resistance.
Examples of the pearl pigment include white pearl pigment, interfering pearl pigment, colored pearl pigment and the like.

The average length of the pearl pigment is preferably 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 values of the lengths of any 20 particles (pearl pigment or metal scales) observed with an optical microscope or an electron microscope from the plane direction of the lid material. Is required as. The length of one pearl pigment and the metal scale means the maximum length of one pearl pigment and the metal scale in the plane direction.

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 μm.
The average thickness of the pearl pigment and the metal scale is determined as the average value of the thickness of any 20 particles (pearl pigment or metal scale) obtained by observing the cross section of the lid material with an optical microscope or an electron microscope. The thickness of one pearl pigment and metal scale is obtained by dividing a cross-sectional image of one pearl pigment and metal scale into five regions having equal lengths in the length direction, and the thickness of the central portion of each region ( _{t 1, t 2, t 3} , t 4, t 5) were _measured, it means an average of the t 1 ~t _5.

The content of the pearl pigment is preferably 40 to 90% by mass, more preferably 50 to 85% by mass, and further preferably 50 to 85% by mass of the total solid content of the pattern layer from the viewpoint of obtaining sufficient glossiness. Is 60 to 80% by mass.

Examples of the material of the metal scale as the glitter pigment include metals and alloys such as aluminum, gold, silver, brass, titanium, chromium, nickel, nickel chromium, and stainless steel.
The metal scale is obtained, for example, obtained by peeling a metal thin film formed by vacuum-depositing the metal or alloy on a plastic film from the plastic film, crushing and stirring the peeled metal thin film, or a powder of the metal or alloy. And a solvent are mixed, and the powder obtained by spreading and / or pulverizing the powder with a medium stirring mill, a ball mill, an attritor, or the like, or a resin-coated surface thereof can be used. it can.

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

The content of the 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 brilliance and microwave oven resistance. It is more preferably 40% by mass or less, and further 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 a base material layer or an intermediate base material, drying, or the like.

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.

<Intermediate base material layer>
The intermediate base material layer is provided between the base material layer and the pressure-sensitive adhesive layer as necessary for the purpose of improving the strength and processability of the lid material, adjusting the texture of the lid material, and the like. It is a layer. Examples of the constituent material of the intermediate base material layer include a plastic film and a paper base material.

As the plastic film and the paper base material as the intermediate base material layer, the same ones as those of the plastic film and the paper base material as the base material layer described above can be used.

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 exemplified in the base material layer.
When the intermediate base material layer is provided, it is preferable to have an adhesive layer between the base material layer and the intermediate base material layer.

<Other layers>
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. Of these, the pattern layer is preferably arranged on the outer layer side of the base material layer or between the base material layer and the sealant layer.

<Layer structure of lid material>
An embodiment of the layer structure of the lid material is shown below. In the following (B1) to (B8), the layer on the left side is the outer layer side, and "/" indicates the boundary of each layer.
(B1) Plastic film / heat-generating printing layer / pattern layer / adhesive layer / intermediate plastic film / adhesive layer / sealant layer (B2) Plastic film / pattern layer / heat-generating printing layer / adhesive layer / intermediate plastic film / adhesive Layer / Sealant layer (B3) Plastic film / Gas barrier layer / Heat-generating printing layer / Picture layer / Adhesive layer / Intermediate plastic film / Adhesive layer / Sealant layer (B4) Plastic film / Heat-generating printing layer / Picture layer / Adhesive layer / Gas barrier layer / Intermediate plastic film / Adhesive layer / Sealant layer (B5) Plastic film / Heat-generating printing layer / Pattern layer / Intermediate plastic film / Adhesive layer / Sealant layer (B6) Design layer / Heat-generating printing layer / Paper substrate / Adhesive layer / Intermediate plastic film / Adhesive layer / Sealant layer (B7) Picture layer / Heat-generating printing layer / Paper substrate / Adhesive layer / Sealant layer (B8) Plastic film / Picture layer / Heat-generating printing layer / Adhesive Layer / sealant layer

[Container with lid for heating microwave oven]
The container with a lid for heating a microwave oven of the present invention is a container with a lid having a flange at the opening, a container body made of paper for accommodating the contents, and a lid material for sealing the container body. The lid material is the lid material of the present invention described above, and has a heat-sealed region in which at least a part of the flange and the sealant layer of the lid material are heat-sealed.
It is a thing.

FIG. 5 is a perspective view showing an embodiment of a container with a lid for heating a microwave oven.
The packaging container 100 with a lid for heating a microwave oven of FIG. 5 includes a container body 10 and a lid material 20 for sealing the container body. Further, the container body 10 has an opening on the upper surface and a flange 12 on the outer peripheral edge of the opening. Further, as shown in FIG. 5, the opening is sealed by a heat-sealing region H in which the flange and the sealant layer are heat-sealed (the shaded portion in FIG. 5 is the heat-sealing region H). Reference numeral 27 in FIG. 5 indicates a gripping portion of the lid material.

<Container body>
The container body has a flange at the opening. The container body may be made of paper or plastic.

When the container body is made of paper, the type of paper is not particularly limited. The basis weight of the paper is not particularly limited, but the paper forming the body ^{is preferably about 150 to 400 g / m 2} , and the paper forming the bottom is about ^{150 to 250 g / m 2.} Is preferable.
When paper is used, it is preferable to have a resin layer on both sides or one side of the paper from the viewpoint of protecting the material to be packaged and from the viewpoint of suppressing leakage of the liquid material to be packaged. Further, from the viewpoint of heat insulating property, the resin layer may be foamed.
Examples of the resin constituting the resin layer include polyolefin resins such as polyethylene and polypropylene, polyester, ethylene-vinyl acetate copolymer and the like, and polyethylene is preferable.
The thickness of the resin layer is preferably about 15 to 60 μm. The thickness of the resin layer on the outer layer side of the paper is preferably 15 to 20 μm, and the thickness of the resin layer on the inner layer side of the paper is preferably 25 to 60 μm.

Further, the paper may be made by laminating a plastic film for the purpose of increasing the strength and gas barrier property of the container body. Further, in order to further enhance the gas barrier property, the plastic film is preferably a vapor-deposited film.

The paper container body can be manufactured, for example, by appropriately processing and adhering the paper forming the body and the paper forming the bottom. The flange can be formed, for example, by bending the paper forming the body.

When the container body is made of plastic, examples of the plastic include polyethylene, polypropylene, polyethylene terephthalate and the like. Among these, polypropylene is preferable from the viewpoint of oil resistance and heat resistance to the oil contained in the contents. The plastic constituting the container body may be a single layer or a multi-layer.
The plastic container body can be manufactured, for example, by vacuum forming or vacuum forming a sheet-shaped plastic film, injection molding of a thermoplastic, or the like.

The container body has an opening on the upper surface. Further, the container body is provided with a flange on the outer peripheral edge of the opening.
The shape of the container body may be any one having the above-mentioned shape, and the shape beyond that is not limited. For example, the container body of FIG. 5 has a substantially circular bottom and opening, but the bottom and opening may have a shape other than a circle such as an ellipse or a quadrangle. Further, although the container body of FIG. 5 has a larger opening than the bottom portion, the sizes of the bottom portion and the opening portion may be substantially the same, or the opening portion may be smaller than the bottom portion. .. Further, although the container body of FIG. 5 has a flat bottom, the container body may have legs. Further, although the flange of the container body in FIG. 5 is flat, the shape of the flange may be annular.
The diameter and depth of the container body may be appropriately determined in consideration of the type and amount of the contents, the design, and the like.

The width of the flange of the container body is preferably about 2 to 15 mm from the viewpoint of sealing property and easy peeling property.

The flange may have a protruding portion that protrudes toward the center of the container body. By having a protruding portion in a part of the flange, when heating in a microwave oven, the load based on the internal pressure of the sealing container is concentrated on the portion corresponding to the protruding portion in the heat seal region, and the portion is peeled and vaporized to maintain the internal pressure. Can be easily escaped. However, considering that it is necessary to change the shape of the seal head when the flange has a protruding portion and that the lid material of the present invention can be peeled and steamed without the protruding portion, the flange protrudes. It is preferable not to have a part.

<Lid material>
As the lid material, the lid material for the microwave oven heating container of the present invention described above can be used.

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

As shown in FIG. 5, the heat seal region is preferably formed continuously in a strip shape or a linear shape so as to go around the flange once.
The area of the heat seal region may match the area of the flange. In other words, the sealant layer may be heat-sealed on all of the flanges. On the other hand, it is not necessary to heat-seal the sealant layer to a part of the flange so that the area of the heat-sealed region and the area of the flange do not match.

The width of the heat seal region is preferably 10% to 100% of the width of the flange, and more preferably 20 to 80%.

<Contents>
The contents to be stored in the container body are not particularly limited, and may be a liquid substance or a solid substance.

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

1. 1. Measurement and evaluation 1-1. Resistivity of heat-generating printing layer After forming the heat-generating printing layer of the lid material of Examples and Comparative Examples, and before bonding the intermediate base material layer to the heat-generating printing layer, in the MD direction and TD direction of the heat-generating printing layer. The resistance value was measured. The measurement was performed by the two-terminal method with a constant current (DC 60A) and a distance between measurements of 5 mm. The measuring device used was the product name "KEW MATE MODEL 2000A" manufactured by Kyoritsu Electric Instruments Co., Ltd.
The lid material of the embodiment corresponds to a direction in which the MD direction of the heat generation printing layer is orthogonal to the XY direction of the condition 1 and the TD direction is orthogonal to the XY direction of the condition 1. On the contrary, the lid material of the comparative example corresponds to the direction in which the TD direction of the heat generation printing layer is orthogonal to the XY direction of the condition 1 and the MD direction is orthogonal to the XY direction of the condition 1.

1-2. Peeling and Steaming of Containers with Lids Twenty evaluation samples were prepared by filling the containers with lids of each Example and Comparative Examples with 150 ml of water. Each evaluation sample was heated in a tableless microwave oven having an output of 600 W for 120 seconds, and it was visually confirmed whether or not the lid material was partially peeled off and steamed, and the samples were ranked according to the following criteria.
A: The lid material of all samples is partially peeled off and steamed.
C: Of the 20 samples, even one that did not peel and vaporize.

2. Preparation of lid material [Example 1]
After corona discharge treatment is applied to one surface of the base material layer (stretched PET film having a thickness of 12 μm), the pattern layer forming ink is gravure-printed and dried, and the picture layer having a dry film thickness of 1.5 μm is applied to the base material layer. Formed on the entire surface of.
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 printing layer having a thickness of 0.5 μm.
Next, an intermediate base material layer (stretched Ny, thickness 15 μm) was bonded to the surface of the heat-generating ink layer by a dry laminating method using a polyurethane-based adhesive.
Next, an adhesive layer-forming ink containing a polyurethane-based 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 extruded 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 layer made of an ethylene-methacrylic acid copolymer (melting point 98 ° C.) and having a thickness of 20 μm, and the layer far from the adhesive layer is a low-density polyethylene. It is a layer having a thickness of 10 μm composed of a mixture (melting point 105 ° C.) and polybutene-1 (melting point 125 ° C.) (mass ratio 65:35).
Next, the laminate obtained in the above step was cut into a circular shape having a diameter of 103 mm to obtain a lid material of Example 1. At the time of cutting, the cutting was performed so that the XY direction of the condition 1 coincided with the MD direction of the heat generating ink layer. The heat generating region of the lid material of Example 1 has a shape shown in FIG. 3 in a plan view, the length on the inner peripheral side is 20 mm, the length on the lateral peripheral side is 20 mm, and the outer peripheral edge is the outer peripheral edge of the lid material. Was consistent with.
The lid material used in Example 1 is 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 (note: the heat-generating ink layer is a part of the surface) from the outer layer side. It has a stretched Ny), an adhesive layer and a sealant layer.

[Example 2]
A lid material of Example 2 was obtained in the same manner as in Example 1 except that the thickness of the heat-generating printing layer was changed to 1 μm.

[Example 3]
A lid material of Example 3 was obtained in the same manner as in Example 1 except that the pattern of the heat-generating printing layer was changed. The heat generating region of the lid material of Example 3 has a shape shown in FIG. 3 in a plan view, the length on the inner peripheral side is 25 mm, the length on the lateral peripheral side is 15 mm, and the outer peripheral edge is the outer peripheral edge of the lid material. Was consistent with.

[Example 4]
A lid material of Example 3 was obtained in the same manner as in Example 1 except that the pattern of the heat-generating printing layer was changed. The heat generating region of the lid material of Example 3 has a shape shown in FIG. 3 in a plan view, the length on the inner peripheral side is 28 mm, the length on the lateral peripheral side is 23 mm, and the outer peripheral edge is the outer peripheral edge of the lid material. Was consistent with.

[Comparative Example 1]
A lid material of Comparative Example 2 was obtained in the same manner as in Example 1 except that the XY direction of Condition 1 coincided with the TD direction of the heat generating ink layer at the time of cutting.

[Comparative Example 2]
A lid material of Comparative Example 2 was obtained in the same manner as in Example 2 except that the XY direction of Condition 1 coincided with the TD direction of the heat generating ink layer at the time of cutting.

[Comparative Example 3]
A lid material of Comparative Example 3 was obtained in the same manner as in Example 3 except that the XY direction of Condition 1 coincided with the TD direction of the heat generating ink layer at the time of cutting.

[Comparative Example 4]
A lid material of Comparative Example 4 was obtained in the same manner as in Example 4 except that the XY direction of Condition 1 coincided with the TD direction of the heat generating ink layer at the time of cutting.

3. 3. Preparation of a container with a lid [Example 1]
A paper container body having a flange at the opening was prepared.
The body of the container body is made of a member in which resin layers are formed on both sides of the paper (paper basis weight is 250 g / m ² , the thickness of the resin layer on the outer layer side is 15 μm, and the thickness of the resin layer on the inner layer side is 25 μm). The bottom of the container body is a member in which resin layers are formed on both sides of the paper (paper basis weight is 200 g / m ² , the thickness of the resin layer on the outer layer side is 15 μm, and the resin layer on the inner layer side is formed. It is formed from a thickness of 25 μm).
The flange of the container body was circular, the inner diameter of the flange was 90 mm, the outer diameter was 100 mm, and the depth of the main body was 95 mm.

After storing 150 g of water as the content in the container body, the lid material of Example 1 was heat-sealed under the following conditions to obtain a container with a lid for heating the microwave oven of Example 1. As the heat sealer, a trace sealer manufactured by Shinwa Machinery Co., Ltd. was used. The width of the heat seal region was 2.5 mm.
<Heat seal condition of Example 1>
・ Temperature: 175 ℃
・ Time: 1.5 seconds ・ Pressure: 2.0 MPa (air cylinder type)

From the results shown in Table 1, it can be confirmed that the lid material for the microwave oven heating container of the present invention has high certainty of peeling and steaming and has stable quality.

10 Container body 11 Opening 12 Flange 16 Body 17 Bottom H Heat seal area 20 Lid material 21 Base material layer 23 Pattern layer 25 Sealant layer 26 Heat-generating printing layer 26a Heat-generating area 27 Holding part 20i Outer peripheral edge of lid material 26i Heat-generating area Outer peripheral edge 26ii Inner peripheral edge of heat generating area 26iii Side peripheral edge of heat generating area 100 Container with lid for heating microwave oven

Claims (3)

A lid material having a base material layer and a sealant layer having a heat-generating printing 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. And
When the region having the heat-generating printing layer in the surface of the lid material is defined as the heat-generating region, at least a part of the outer peripheral edge of the heat-generating region is arranged in the vicinity of the outer peripheral edge of the lid material.
A lid material for a microwave oven heating container that satisfies the following condition (1) when the central point of the lid material is defined as X and the midpoint of the line forming the outer peripheral edge of the heat generating region is defined as Y.
<Condition 1>
Resistance value of the heat-generating printing layer in the XY direction <Resistance value of the heat-generating printing layer in the direction orthogonal to the XY direction The lid material for a microwave oven heating container according to claim 1, wherein the heat-generating printing layer has a resistance value of 1.5 kΩ or more and 100 kΩ or less in the XY direction. A container with a lid having a flange at the opening and provided with a paper container body for accommodating the contents and a lid material for sealing the container body, wherein the lid material is claimed in claim 1 or 2. A container with a lid for heating a microwave oven, which is the lid material according to the above and has a heat-sealed region in which at least a part of the flange and the sealant layer of the lid material are heat-sealed.

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