JP2017080964A - Laminate for heat insulation container and heat insulation container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for a heat insulation container capable of reducing a manufacturing cost and easy to deal with when molding a heat insulation container, and also to provide a heat insulation container molded using the laminate for a heat insulation container.SOLUTION: A laminate 10 for a heat insulation container at least includes: a cover layer 11 configured with low-density polyethylene; a substrate layer 12 configured with paper; a clay coat layer 13 containing clay; and an innermost layer 14 configured with medium-density polyethylene, laminated from an outer side. The thickness of the innermost layer 14 is 30 μm or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a laminated body for a heat insulating container and a heat insulating container.

  Conventionally, a laminated body for a heat insulating container in which a foam layer is provided on one surface of a base material made of paper and a non-foam layer is provided on the other surface is known. For example, Patent Document 1 discloses a heat insulating container having a layer structure of foamed low density polyethylene (LDPE) / paper / medium density polyethylene (MDPE) from the surface side.

JP-A-57-110439

  A general heat insulating container and a laminated body for a heat insulating container for molding the heat insulating container including the heat insulating container disclosed in Patent Document 1 are resins for foaming on the surface of paper as a base material (in Patent Document 1). Is a low-density polyethylene), and another resin (medium-density polyethylene in Patent Document 1) is also provided on the back side to form a laminated body for a heat insulating container. By heating this, moisture contained in the paper is evaporated. The surface side resin (low density polyethylene in Patent Document 1) is foamed by this water vapor, so-called water vapor foaming. Therefore, in order to efficiently foam the resin on the surface side, it is necessary to guide water vapor generated from the paper during heating to the resin side on the surface side. In Patent Document 1, medium density polyethylene having a higher density than low density polyethylene used on the front surface side is used as the resin on the back surface side. As the resin on the back side, in addition to medium density polyethylene, various resins are used, including high density polyethylene (HDPE), which has a higher melting point than the surface side resin and can suppress the permeation of water vapor.

  However, no matter what resin is used as the resin on the back surface side, the permeation of water vapor is suppressed, and a certain thickness is required to obtain a thick foamed layer. Problems may occur when molding containers or sealing lids.

  The present invention has been made in such a situation, and mainly provides a heat-insulated container laminate that is easy to handle when a heat-insulating container is molded, and a heat-insulated container molded using the heat-insulating container laminate. Let it be an issue.

  In order to solve the above problems, the present invention includes a cover layer composed of low-density polyethylene, a base material layer composed of paper, a clay coat layer containing clay, and an innermost layer composed of medium-density polyethylene, from the outer surface side. , At least a laminated body for a heat insulating container, wherein the innermost layer has a thickness of 30 μm or less.

In the above invention, the basis weight of the paper constituting the base material layer may be 240 to 340 g / m ² .

  In the above invention, the cover layer may be foamed and the thickness thereof may be 200 to 1000 μm.

  Moreover, another invention for solving the above-mentioned problems is a heat insulating container, characterized by molding the above-mentioned laminated body for a heat insulating container.

  According to the laminate for a heat insulating container of the present invention, since the clay coat layer having a water vapor shielding effect is provided on the inner surface side of the base material layer, water vapor generated from the base material can be efficiently guided to the cover layer side. And the cover layer can be efficiently foamed. Moreover, since the clay coat layer is provided, the thickness of the innermost layer provided on the inner surface side can be designed to be thinner than the conventional one.

  Even if it exists in the heat insulation container of this invention, since it shape | molds using the laminated body for heat insulation containers of the said this invention, there exists an effect similar to the above.

It is sectional drawing of the laminated body for heat insulation containers of the state which the cover layer concerning embodiment of this invention does not foam. It is sectional drawing of the laminated body for heat insulation containers of the state which the cover layer concerning the embodiment of this invention foamed.

  Hereinafter, the laminated body for heat insulation containers and the heat insulation container concerning embodiment of this invention are demonstrated in detail using drawing.

  FIG. 1 is a cross-sectional view of a laminate for a heat insulating container in a state where a cover layer is not foamed according to an embodiment of the present invention.

  FIG. 2 is a cross-sectional view of a laminate for a heat insulating container in a state where a cover layer is foamed according to an embodiment of the present invention.

  As shown in FIG. 1, a laminated body 10A for a heat insulating container according to this embodiment includes a cover layer 11A made of low-density polyethylene, a base material layer 12 made of paper, and a clay coat including clay from the outer surface side. It is constituted by laminating at least a layer 13 and an innermost layer 14 made of medium density polyethylene.

  And as shown in FIG. 2, the low density which comprises a cover layer with the water vapor | steam which generate | occur | produces from the paper which comprises the base material layer 12 by heating 10A of laminated bodies for heat insulation containers concerning this embodiment shown in FIG. Polyethylene is in a foamed state.

  In the present specification, both the state where the cover layer (11A) is not foamed and the state where the cover layer (11) is foamed are expressed as a laminate for a heat insulating container (10A, 10). To do. Moreover, when forming a heat insulation container using the laminated body for heat insulation containers, the side located outside the heat insulation container is referred to as an “outer surface side”, and the side located inside the heat insulation container is referred to as an “inner surface side”. In FIG. 1 and FIG. 2, the upper side is the “outer surface side” and the lower side is the “inner surface side”.

  Below, each layer which comprises laminated body 10A, 10 for heat insulation containers is demonstrated.

(Cover layer)
11 A of cover layers before foaming are comprised from the low density polyethylene. Specifically, as the low density polyethylene (LDPE) in the present embodiment, a high pressure ethylene homopolymer is preferably used. Further, linear low density polyethylene (LLDPE) which is a copolymer of ethylene and an α-olefin other than ethylene such as propylene, butene, pentene, hexene, octene, 4-methylpentene-1 is also preferably used. The density of the low density polyethylene is not particularly limited as long as it is generally referred to as low density polyethylene, but is about 0.87 to 0.925 g / cm ³ , and its melt index M.I. I. Although it is not specifically limited, Usually, it is about 4-30. Further, the melting point of the low density polyethylene is not particularly limited as long as it is within the melting point range of a normal low density polyethylene, but is about 100 to 110 ° C.

  The method for forming the cover layer 11 </ b> A before foaming is not particularly limited. For example, the cover layer 11 </ b> A is formed by extrusion coating on one surface of the base material layer 12. In addition, the cover layer 11 after foaming may eventually become the surface of the heat insulating container, but in order to impart design properties to the heat insulating container, a printed layer (not shown) is formed on the surface of the cover layer 11 before foaming. In this case, in order to improve the adhesion of the printing ink used for the printing layer, the surface of the cover layer 11A before foaming is subjected to a surface treatment such as a corona treatment. There is.

  Although the thickness of 11 A of cover layers before foaming is not specifically limited, Usually, it is about 10-80 micrometers.

  The cover layer 11A before foaming shown in FIG. 1 is formed on the base material layer 12 as described above, and is heated by the water vapor generated from the paper constituting the base material layer 12 as shown in FIG. The cover layer 11 is in the foamed state. The heating temperature at this time is not lower than the melting point of the low-density polyethylene as a material and is not particularly limited as long as the laminated body 10 for a heat insulating container is not altered, but is usually 100 to 200 ° C., preferably 110-130 ° C. The heating time is not particularly limited, but is usually about 10 seconds to 5 minutes. The heating method is not particularly limited, and heating can be performed by a conventionally known method. Examples include heating with hot air, infrared rays, far infrared rays, microwaves, high frequencies, and the like.

  The thickness of the cover layer 11 after foaming is not particularly limited, but is usually about 200 to 1000 μm.

(Base material layer)
The base material layer 12 is made of paper. Since this paper becomes a basic material constituting the heat insulating container, it is possible to use paper having formability, bending resistance, rigidity, waist, strength and the like. As paper, for example, it is a main strength material, and uses various types of paper base materials such as high-size bleached or unbleached paper base, or pure white roll paper, kraft paper, paperboard, processed paper, milk base paper, etc. can do. The base material layer 12 may be a laminate of a plurality of these papers. The paper has a basis weight of about 80 to 600 g / m ² , preferably about 100 to 450 g / m ² , and has a thickness of about 110 to 860 μm, preferably about 140 to 640 μm. . Note that, for example, letters, figures, symbols, and other desired patterns can be arbitrarily formed on the paper base by a normal printing method.

As described above, moisture contained in the paper constituting the base layer 12 is required for foaming the cover layer 11A. Therefore, the cover layer 11A described above and the clay coat layer 13 described later are applied to the base layer 12. The paper constituting the base material layer 12 in any stage such as a stage before being provided, or at the same time as these are provided, and further, a stage before heating the laminated body 10A for the heat insulating container is formed. You may perform the moisture adjustment process of adjusting a moisture content. Depending on how much the cover layer 11A is foamed, for example, it is preferable to adjust the water content in the paper to be about 7.5 to 9.5%, and the basis weight is 250 g / m ² . In the case of using, it is preferable to perform the moisture adjustment step. The specific method of the moisture adjustment step is not particularly limited, and for example, paper may be soaked in water.

(Clay coat layer)
The clay coat layer 13 is obtained by applying a coating liquid containing clay to the base material layer 12 and laying clay particles on the surface of the base material layer 12 on which the cover layer is not provided. The clay used in the laminate for an insulated container of the present embodiment is not particularly limited as long as it is generally called clay or clay, but kaolin, talc, bentonite, smectite, vermiculite, mica, chlorite, wood Knot clay, gyrome clay, halloysite, mica, etc. are used. Of these, kaolin and talc are preferably used as the clay. Kaolin has excellent concealability and water absorption, and talc has low hardness (Mohs hardness 1) and excellent heat resistance. Improvement in dimensional stability can be expected.

  The clay coat layer 13 preferably contains calcium carbonate, titanium dioxide, amorphous silica, expandable barium sulfate, satin white and the like as a pigment in addition to clay. By using calcium carbonate or titanium dioxide as a pigment, the smoothness of the surface of the clay coat layer 13 can be increased, and the concealability can be increased. Furthermore, calcium carbonate is preferably used because it is inexpensive.

  The coating liquid for coating the clay coat layer 13 contains the above clay, a binder, and, if necessary, other pigments and additives in a solvent. As the solvent, water, alcohol or the like is usually used. The binder is usually a latex binder (eg, styrene butadiene latex, acrylic latex vinyl acetate latex), water soluble binder (eg starch (modified starch, oxidized starch, hydroxyethyl etherified starch, phosphate ester). Modified starch), polyvinyl alcohol, casein and the like. Examples of additives that can be used include pigment dispersants, antifoaming agents, antifoaming agents, viscosity modifiers, lubricants, water resistance agents, water retention agents, coloring materials, and printability improvers.

  The blending ratio of the coating liquid for the clay coat layer 13 is not particularly limited, but is preferably about clay: pigment: binder = 1-20%: 50-90%: 10-30%.

  The coating method of the clay coat layer 13 is not particularly limited, and a conventionally known coating method is used, but a coating method such as air knife coating, blade coating, short dwell coating, or cast coating is used.

Although the coating amount and thickness of the clay coat layer 13 are not particularly limited, the basis weight after drying is usually 5 to 40 g / m ² , preferably 10 to 40 g / m ² . If the basis weight after drying is less than 5 g / m ² , water vapor generated from the paper constituting the base material layer 12 cannot be effectively blocked, and the cover layer 11 cannot be brought into a desired foamed state. If the basis weight after drying exceeds 40 g / m ² , the overall thickness of the laminated body 10 for a heat-insulating container may become too thick, and the suitability for production may deteriorate.

  In addition, since the material in which the clay coat layer 13 which consists of the above-mentioned material etc. was already formed in the base material layer 12 which consists of paper is marketed now, you may use this. In this case, another layer may be provided at an appropriate position.

  Further, in a normal case, the clay coat layer is provided in order to improve the printability of paper. This is because printing quality is improved when printing is performed on paper on which the clay coat layer is formed. In the heat insulating container laminate 10 according to the present embodiment, the clay coat layer 13 is formed on the inner side of the base material layer 12, that is, on the surface of the packaging material 10 on which the printing layer is not provided, and the paper of the base material layer 12 is formed. Is different from the conventional clay coat layer in that it prevents the water vapor generated from the permeation from passing therethrough and allows the water vapor to go out to the cover layer 11 side.

(Innermost layer)
The innermost layer 14 is provided on the surface of the clay coat layer 13 and is characterized by being made of medium density polyethylene and having a thickness of 30 μm or less. In the laminated bodies 10A and 10 for the heat insulating container according to the present embodiment, the clay coat layer 13 is provided inside the base material layer 12 as described above, and therefore, it is generated from the paper constituting the base material layer 12. Most of the water vapor can be blocked by the clay coat layer 13, and as a result, the thickness of the innermost layer is designed to be 30 μm or less, which may cause problems during molding and seal sealing. Can be prevented. Moreover, in the laminated bodies 10A and 10 for heat insulating containers according to this embodiment, since medium density polyethylene is used as the innermost layer, the pinhole resistance is also excellent.

The medium density polyethylene in the present embodiment is not particularly limited as long as it is generally in the range of medium density polyethylene. However, since it is used as the innermost layer of a heat insulating container, medium density polyethylene without additives (non-added medium density) Polyethylene) is preferably used. The density of the medium density polyethylene is not particularly limited as long as it is generally referred to as medium density polyethylene, but it is about 0.925 to 0.940 g / cm ³ , and its melt index M.I. I. Although it is not specifically limited, Usually, it is about 1-20. Moreover, the melting point of the medium density polyethylene is the melting point range of the normal medium density polyethylene, and is usually about 110 to 135 ° C.

A method for forming the innermost layer 14 is not particularly limited, and is not particularly limited as in the case of the cover layer 11. Usually, extrusion coating, laminate of a film prepared in advance, dry lamination, or the like is used. Further, in forming the innermost layer 14, medium density polyethylene and high density polyethylene may be coextruded so that the medium density polyethylene is inside, and the density of the high density polyethylene in this case is 0.00. It is about 940-0.970 g / cm < ³ >, and melting | fusing point is about 125-140 degreeC.

  The thickness of the innermost layer 14 is 30 μm or less, and preferably about 15 to 25 μm. If the thickness of the innermost layer is less than 15 μm, there is a risk of film breakage at the time of extrusion lamination molding, and a sealing failure may occur when molding a cup-shaped heat insulating container using a laminated body for heat insulating containers. This is because productivity may deteriorate. Also, if the innermost layer 14 is thicker than 30 μm, when a cup-shaped heat insulating container is molded using the laminated body for a heat insulating container, the step at the overlapping portion of the top curl becomes large and the lid material is sealed. However, according to the laminated body for a heat insulating container of this embodiment, there is no such fear.

(Other layers)
In the laminated bodies 10A and 10 for a heat insulating container according to the present embodiment, layers that exhibit various functions are included in addition to the cover layer 11, the base material layer 12, the clay coat layer 13, and the innermost layer 14 described above. It may be. For example, a printed layer for imparting design properties may be provided on the cover layer 11, and a surface protective layer may be provided in combination with the printed layer or separately from the printed layer.

  The material of the surface protective layer is not particularly limited, but medium density polyethylene similar to the innermost layer 14 described above may be used. In addition, in the case where the laminates 10A and 10 for a heat insulating container according to the present embodiment have a barrier property, a PET film, a film on which an inorganic oxide is deposited, aluminum, or the like, further inside the innermost layer 14 A barrier layer composed of a metal foil such as MX nylon or the like may be used.

  Moreover, you may provide conventionally well-known various contact bonding layers in order to improve the adhesiveness of each layer between each layer mentioned above.

(Insulated container)
The heat insulation container concerning embodiment of this invention is demonstrated below.

  The heat insulating container according to the present embodiment is characterized in that the cover layer 11 described above is formed by molding the heat insulating container laminate 10 after foaming. Although it does not specifically limit about a specific manufacturing method, For example, after forming the laminated body 10 for heat insulation containers concerning this embodiment, a printing layer is formed as needed, it punches, and it is an end surface as needed The contents are not contacted with the end face by skive hemming, and the bottom part and, if necessary, the top part are heat-sealed by hot air heating, flame heating, or the like with a molding machine to obtain an insulated container.

  About the shape of this heat insulation container, what is necessary is just to determine suitably according to a use, the objective, etc. For example, shapes, such as a shape of a gable top type, a brick type, a flat top type, a cup type, etc. are mentioned. In addition, for example, a polyethylene cap, a pull tab type opening mechanism, or the like may be appropriately provided at the spout of the heat insulating container.

  The contents filled in the heat insulating container according to the present embodiment are not particularly limited, and various solids and liquids can be used as the contents. For example, when the shape of the heat insulating container is a cup shape, the contents may be dry noodles, miso soup, various soups, and the like.

  The present invention will be described more specifically with reference to examples and comparative examples.

Example 1
A paper having a basis weight of 280 g / m ² (a cup base paper manufactured by Nippon Paper Industries Co., Ltd.) is prepared as a base material layer, and a clay coat layer composed of the following coating liquid A for clay coat layer is formed on one surface thereof by an air knife coating method. did. The clay coat layer had a basis weight of 20 g / m ² .

<Clay coat layer coating liquid A>
Kaolin clay 10% by mass
Calcium carbonate 70% by mass
Styrene butadiene latex 9% by mass
Polyvinyl acetate latex 9% by mass
Sodium polyacrylate 0.4% by mass
Other 1.6% by mass
Above, solid content

A medium density polyethylene resin (density: 0.940 g / cm ³ , melting point: 133 ° C., melt index MI: 6.5) is applied to the surface of the clay coat layer formed on the base material layer at a temperature of 310 ° C. The innermost layer was formed by extruding from a T die and forming an extrusion laminate so that the take-up speed was 70 m / min, the air gap length was 140 mm, and the thickness was 20 μm.

Further, a low-density polyethylene resin (density: 0.917 g / cm ³ , melting point: 103 ° C., melt index MI: 15) is provided on the surface of the base material layer opposite to the surface on which the clay coat layer is formed. Was coated by extrusion to form a cover layer having a thickness of 60 μm to obtain a packaging material.

  Next, this packaging material was heated at 120 ° C. for 5 minutes to obtain a laminate for a heat-insulating container of Example 1 in which the cover layer was foamed. In addition, when the thickness of the cover layer was measured using a thickness meter (Dial Thickness Gauge G: manufactured by Ozaki Seisakusho Co., Ltd.), it was about 1000 μm.

The structure of the laminated body for heat insulation containers of Example 1 is as follows.
From outside, LDPE 1000 μm / paper 280 g / m ² / clay coat layer 20 g / m ² / MDPE 20 μm

(Example 2)
A laminated body for a heat insulating container of Example 2 was obtained under the same conditions as in Example 1 except that paper having a basis weight of 250 g / m ² was used as the base material layer. The cover layer had a thickness of about 900 μm.

The structure of the laminated body for heat insulation containers of Example 2 is as follows.
From outside, LDPE 900 μm / paper 250 g / m ² / clay coat layer 20 g / m ² / MDPE 20 μm

(Comparative Example 1)
The laminated body for heat insulation containers of the comparative example 1 was obtained on the same conditions as the said Example 1 except not having formed the clay coat layer. The cover layer had a thickness of about 700 μm.

The structure of the laminated body for heat insulation containers of Comparative Example 1 is as follows.
From the outside, LDPE 700 μm / paper 280 g / m ² / MDPE ²⁰ μm

(Comparative Example 2)
A laminated body for a heat insulating container of Comparative Example 2 was obtained under the same conditions as in Example 1 except that the clay coat layer was not formed and the thickness of the innermost layer was 40 μm. The cover layer had a thickness of about 1000 μm.

The structure of the laminated body for heat insulation containers of Comparative Example 2 is as follows.
From the outside, LDPE 1000 μm / paper 280 g / m ² / MDPE 40 μm

(Comparative Example 3)
A laminate for a heat-insulating container of Comparative Example 3 was obtained under the same conditions as in Example 1 except that paper having a basis weight of 250 g / m ² was used as the base material layer and the clay coat layer was not formed. . The cover layer had a thickness of about 650 μm.

The structure of the laminated body for heat insulation containers of Comparative Example 3 is as follows.
From the outside, LDPE650 μm / paper 250 g / m ² / MDPE20 μm

(Comparative Example 4)
Under the same conditions as in Example 1 except that paper having a basis weight of 250 g / m ² was used as the base material layer, the clay coat layer was not formed, and the thickness of the innermost layer was 40 μm. The laminated body for heat insulation containers of the comparative example 4 was obtained. The cover layer had a thickness of about 900 μm.

The structure of the laminated body for heat insulation containers of Comparative Example 4 is as follows.
From the outside, LDPE 900 μm / paper 250 g / m ² / MDPE 40 μm

(Evaluation regarding cover layer thickness)
As can be seen by comparing the thickness of the cover layer after foaming in the laminates for heat-insulating containers of Examples 1-2 and Comparative Examples 1-4, the laminates for heat-insulating containers of Examples 1-2 of the present invention In this case, since a clay coat layer is provided, a cover layer having a sufficient thickness of 900 μm or more is formed even when the innermost layer has a thickness of 20 μm. In Examples 1 and 3, since the clay coat layer is not provided, the cover layer having a sufficient thickness is not formed. In Comparative Examples 2 and 4, a cover layer having a sufficient thickness is formed. This is because the thickness of the innermost layer is increased (40 μm).

(Evaluation on sealing performance of lid materials)
Each of the laminates for heat insulating containers of Examples 1 and 2 and Comparative Examples 1 to 4 was molded into a cup shape, and the lid member was sealed at 170 ° C., 0.15 MPa for 1 second. The airtightness at this time was confirmed by peeling the lid material and visually confirming the seal mark, and using a microcheck penetrating liquid (manufactured by Taiho Kozai Co., Ltd.). The results are shown in Table 1 below together with the thickness of the cover layer.

  In Table 1, ◯ indicates that no seal failure occurred, and Δ indicates that a seal failure occurred.

  As can be seen from Table 1 above, in the heat insulation container laminates of Comparative Example 2 and Comparative Example 4, the innermost layer is too thick, resulting in poor sealing of the lid. Yes.

10 ... Laminated body for insulated container (after foaming)
10A ... Laminated body for heat insulation container (before foaming)
11 ... Cover layer (after foaming)
11A ... cover layer (before foaming)
12 ... Base material layer 13 ... Clay coat layer 14 ... Innermost layer

Claims (4)

Laminate for heat insulation container comprising at least a cover layer composed of low density polyethylene, a base material layer composed of paper, a clay coat layer containing clay, and an innermost layer composed of medium density polyethylene from the outer surface side. Body,
A laminate for a heat insulating container, wherein the innermost layer has a thickness of 30 μm or less. The basis weight of the paper which comprises the said base material layer is 240-340 g / m < ² >, The laminated body for heat insulation containers of Claim 1 characterized by the above-mentioned.   The laminate for a heat-insulating container according to claim 1 or 2, wherein the cover layer is foamed and has a thickness of 200 to 1000 µm.   The heat insulation container formed by shape | molding the laminated body for heat insulation containers of Claim 3.

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