JP2011168043A - Laminated film, method for manufacturing the same, dew condensation preventing container, and container for food and drink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film easily manufactured and preventing dew condensation even when storing low-temperature contents. <P>SOLUTION: The laminated film includes a foam layer 2 of polyolefin resin formed with open cells, and a solid layer 3 provided on one surface of the foam layer 2 and including thermoplastic resin. The foam layer 2 is formed as an exposed surface 21, and the average bore diameter of the exposed cells is 200-500 μm. The aperture area rate of cells is 30-80%. The foam layer 2 preferably has a porosity of 30-70 vol.% and a bulk density of 0.20-0.60 g/cm<SP>3</SP>, and polyolefin resin preferably includes polypropylene. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laminated film, a method for producing the laminated film, a dew condensation prevention container, and a food and drink container.

Metal cans, plastic bottles, glass bottles, pouch containers, and the like are widely used as containers for storing beverages, frozen desserts, and the like. Containers containing such beverages are often cooled in a refrigerator or the like and used for eating and drinking. However, when the cooled container is taken out of the refrigerator or the like, condensation occurs on the surface of the container, and there is a problem that water droplets generated by the condensation wet the tabletop, fall on clothes, or wet the handle.
To deal with this problem of condensation, attempts have been made to provide a foam made of closed cells on the outer periphery of the container. However, even if a foam is provided to increase the heat insulation of the container, it is possible to effectively prevent condensation. I can't.

For such problems, for example, a labeled container in which a label having a paper layer provided on one side of a plastic film is adhered has been proposed (for example, Patent Document 1). According to this labeled container, the paper layer side of the label is adhered to the body of the container, so that moisture generated between the container and the paper layer is absorbed by the paper layer to prevent condensation.
Moreover, for example, a labeled container having a label in which a film layer in which a plurality of holes are formed and a water absorption layer made of a nonwoven fabric or the like is provided on the inner surface has been proposed (for example, Patent Document 2). According to this labeled container, moisture adhering to the label surface is intended to be removed by absorbing the moisture adhering to the surface of the label from the hole to the water absorption layer.
In addition, for example, a pouch container that includes a bag main body and an outer layer film stacked on the front and back surfaces of the bag main body and that has a gap formed between the bag main body and the outer layer film has been proposed (for example, Patent Document 3). . According to this pouch container, dew condensation on the outer surface of the outer layer film is prevented by providing an air layer between the bag body and the outer layer film.

In addition, containers containing beverages are often heated and used for food and drink. For example, beverages containing metal cans are heated to about 55-60 ° C. and sold. In recent years, for the purpose of improving the flavor of contents, there has been a demand for serving beverages in containers at higher temperatures. On the other hand, when the temperature is raised, the surface of the container becomes high temperature, and handling with bare hands becomes difficult.
In order to solve such a problem, a bottle-type metal can in which a heat-insulating label made of a sheet having a foam layer is attached to the body of a bottle-shaped can body has been proposed (for example, Patent Document 4). According to this bottle-type metal can, the handle can be firmly held without being heated by holding the bottle via the heat insulating label.
In addition, a laminated sheet in which a nonwoven fabric is laminated on the heat-shrinkable film on which the barcode is printed, excluding the part necessary for mechanical reading of the barcode, is used as a label substrate, and this label substrate is formed in a cylindrical shape. A cylindrical label has been proposed (for example, Patent Document 5). According to this cylindrical label, the barcode printed on the heat-shrinkable film can be read while ensuring heat insulation.

JP 2005-62701 A Japanese Patent No. 4252484 Japanese Patent No. 4289978 JP 2003-81267 A JP 2009-175714 A

However, in the inventions of Patent Documents 1 and 2, water droplets on the label surface can be removed, but when the water absorption capacity of the label is exceeded, water droplets adhere to the surface of the labeled container. In particular, in a container with a cap such as a plastic bottle, since it can be closed again after opening, it may be repeatedly put in and out of a refrigerator or the like, and there is a possibility that water droplets on the surface of the container cannot be sufficiently removed only by absorbing water from the label. In addition, the production of these labels requires a process of bonding different materials.
Moreover, although the invention of Patent Document 3 can be applied to a pouch container, it is difficult to apply it to a metal can, a PET bottle, or a glass bottle. In addition, a special process for forming a gap between the bag body and the outer layer film is required.
In addition, although the invention of Patent Document 4 has a certain degree of heat insulation effect, the heat-insulating label surface becomes hot with the passage of time, and handling with bare hands becomes difficult.
Moreover, although the invention of patent document 5 is maintained to such an extent that the surface of a cylindrical label can be handled with bare hands, it requires a complicated process of pasting together non-woven fabrics. Furthermore, in order to read the barcode printed on the heat-shrinkable film, a complicated process of cutting out the nonwoven fabric is required.
The present invention has been made in view of such problems, and an object of the present invention is to provide a laminated film that can prevent dew condensation even when a low-temperature content is accommodated and can be easily manufactured. Furthermore, the present invention aims at a laminated film that can be easily handled with bare hands even when high-temperature contents are accommodated.

The laminated film of the present invention has a polyolefin resin foam layer in which open cells are formed, and a solid layer containing a thermoplastic resin provided on one surface of the foam layer, the foam layer being an exposed surface. The average diameter of the exposed bubbles is 200 to 500 μm, and the open area ratio of the bubbles is 30 to 80%.
The foam layer preferably has a porosity of 30 to 70% by volume, the foam layer preferably has a bulk density of 0.20 to 0.60 g / cm ³ , and the polyolefin resin is Preferably, polypropylene is included.
It is preferable that a bubble reduction part is partially formed in the foam layer, and that the solid layer is printed at a position of the bubble reduction part.

The method for producing a laminated film of the present invention includes coextrusion of a foamable mixture containing a polyolefin resin and a foaming agent and a non-foamable mixture containing a thermoplastic resin, and foaming the foamable mixture to produce the foamed mixture. A solid layer made of a non-foamable mixture containing a thermoplastic resin is formed on one surface of the foam layer while forming the layer.
The method for producing a laminated film of the present invention includes coextrusion of a foamable mixture containing a polyolefin resin and a foaming agent and a non-foamable mixture containing a thermoplastic resin, and foaming the foamable mixture to produce the foamed mixture. While forming a layer, a solid layer made of a non-foamable mixture containing a thermoplastic resin is formed on one surface of the foam layer, and then the foam layer is partially melted to form the bubble reduction part It is characterized by that.
The foam layer and the solid layer are preferably formed by inflation film molding.

The dew condensation prevention container of the present invention is characterized in that the laminated film of the present invention is formed so that the foamed layer is on the outside.
The laminated film may be provided on the outer peripheral surface of a metal, glass, or resin container.

The container for food and drink of the present invention is characterized in that the laminated film of the present invention is formed so that the foamed layer is on the outside.
The laminated film may be provided on the outer peripheral surface of a metal, glass, or resin container.

  The laminated film of the present invention can be easily manufactured and can prevent condensation even when a low-temperature content is accommodated. Furthermore, even when high-temperature contents are stored, it can be easily handled with bare hands.

It is sectional drawing of the laminated film which concerns on 1st embodiment of this invention. It is the elements on larger scale of the laminated | multilayer film of FIG. It is a SEM photograph of the exposed surface of the laminated | multilayer film of this invention. It is sectional drawing of the laminated film which concerns on 2nd embodiment of this invention. 4 is a SEM photograph of the surface of the laminated film of Comparative Example 1. It is a photograph of the surface of a metal can explaining the result of Example 1. It is a photograph of the surface of a metal can explaining the result of Comparative Example 1. It is an enlarged photograph of the exposed surface of the laminated film of Example 6.

[First embodiment]
(Laminated film)
The laminated film which concerns on 1st embodiment of this invention is demonstrated using drawing below. FIG. 1 is a cross-sectional view of the laminated film 1 according to the first embodiment, FIG. 2 is a partial cross-sectional view schematically showing the structure of the foam layer, and FIG. 3 is an exposed surface of the laminated film 1. That is, a scanning electron microscope (SEM) photograph of the surface of the foam layer.
The laminated film 1 has a foam layer 2 and a solid layer 3 provided on one surface of the foam layer 2, and the foam layer 2 side is an exposed surface. In the figure, reference numeral 21 denotes an exposed surface which is a surface on the foam layer 2 side, and reference numeral 31 denotes a solid side surface which is a surface on the solid layer 3 side.

<Foamed layer>
The foam layer 2 is obtained by foaming a polyolefin resin. As shown in FIGS. 2 to 3, in the foamed layer 2, a communication bubble 24 in which the bubbles 23 communicate with each other and a closed cell 26 are formed, and an opening 22 in which the communication bubbles 24 are exposed is formed in the exposed surface 21. Has been.

The polyolefin resin is a homopolymer or copolymer of an olefin such as ethylene or propylene. Examples of such polymers include high-density polyethylene, medium-density polyethylene, high-pressure method low-density polyethylene, linear low-density polyethylene, and the like, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, and the like. Examples thereof include polypropylenes such as ethylene-based copolymers, propylene homopolymers, and propylene-ethylene copolymers, among which polyethylene, polypropylene, and mixtures of polyethylene and polypropylene are preferred. This is because the use of such a polyolefin resin facilitates the formation of the communication bubbles 24.
These polyolefin resins can be used singly or in combination of two or more.

  When a mixture of polyethylene and polypropylene is used, the mixing ratio represented by PE / PP (mass ratio) is preferably 90/10 to 10/90, more preferably 70/30 to 50/50, and even more preferably 75. / 25 to 55/45. This is because the formation of the communication bubbles 24 is facilitated by being within the above range.

  The expansion ratio of the foam layer 2 is preferably 1.5 to 5.0 times, more preferably 2.0 to 4.0 times, and still more preferably 2.3 to 3.5 times. If the expansion ratio of the foam layer 2 is less than 1.5 times, the communication bubbles 24 are difficult to be formed, and if the expansion ratio is more than 5.0 times, it is difficult to form uniform communication bubbles. If the expansion ratio is 1.5 to 5.0 times, the formation of the communication bubbles 24 is easy, and the diameter of the opening 22, the opening area ratio of the exposed surface 21, the porosity and the bulk of the foam layer 2 will be described later. It is easy to control the density. Here, the expansion ratio is a value obtained by the formula of (resin density of the foamed layer before foaming) / (film density of the foamed layer after foaming).

  The thickness of the foamed layer 2 can be determined according to the use of the laminated film 1, and is, for example, preferably 80 to 200 μm, more preferably 90 to 190 μm, and further preferably 100 to 180 μm. If the thickness of the foamed layer 2 is 80 μm or more, the effect of preventing condensation is sufficiently secured, and if it is 200 μm or less, the flexibility of the laminated film 1 is secured.

The opening 22 has an average diameter of 200 to 500 μm, preferably 220 to 470 μm, and more preferably 230 to 350 μm. If the average diameter is 200 μm or more, the effect of preventing condensation can be obtained, and if the average diameter is 500 μm or less, a uniform appearance can be maintained.
The aperture means a diameter calculated by measuring the area of each opening 22 and assuming that the opening 22 is a perfect circle from the measured area.

  In addition, the diameter of the opening 22 is not particularly limited, but is preferably 100 to 3000 μm, and more preferably 200 to 2000 μm. If the aperture is less than 100 μm, the communication bubbles inside the foam layer 2 are difficult to be formed, and if it exceeds 3000 μm, the uniform opening state of the surface cannot be maintained, and unevenness is likely to occur in the expression of the dew condensation prevention effect. The appearance of becomes poor.

The opening area ratio of the exposed surface 21 is 30 to 80%, preferably 35 to 80%, more preferably 45 to 70%. When the opening area ratio is less than 30%, a good dew condensation preventing effect cannot be exhibited, and when it exceeds 80%, the uniform opening state of the exposed surface 21 cannot be maintained, and unevenness tends to occur in the expression of the dew condensation preventing effect. In addition, when the opening area ratio is less than 30%, it is not possible to obtain a good effect of suppressing the temperature of experience.
The opening area ratio is the ratio of the total area of the openings 22 per unit area to the area of the exposed surface 21, and is a value obtained by the following equation (1). In addition, the area of each opening 22 can be measured by image diffraction using SEM.

  Open area ratio (%) = (total area of openings) / (area of exposed surface) × 100 (1)

The porosity of the foam layer 2 is preferably 30 to 70% by volume, more preferably 35 to 65% by volume, and still more preferably 40 to 60% by volume. If the porosity is within the above range, it is possible to further improve the dew condensation prevention effect and the temperature control effect.
The porosity is the ratio of bubbles 23 (hereinafter referred to as “open bubbles”) communicating with the outside of the foam layer 2 through the openings 22 in the foam layer 2 and can be obtained by the following equation (2).

  Porosity (volume%) = (total volume of open cells in the foam layer) / (apparent volume of the foam layer) × 100 (2)

The bulk density of the foam layer 2 is preferably 0.20 to 0.60 g / cm ³ , more preferably 0.30 to 0.55 g / cm ³ , and still more preferably 0.30 to 0.45 g / cm ³ . cm ³ . If the bulk density is within the above range, it is possible to further improve the dew condensation prevention effect and the temperature control effect.

  The diameter of the opening 22, the opening area ratio of the exposed surface 21, the diameter, the average diameter, the porosity and the bulk density of the foamed layer 2 can be adjusted by a combination of the type of polyolefin resin, molding conditions in the manufacturing method described later, and the like. .

<Solid layer>
The solid layer 3 is an unfoamed resin layer made of a resin containing a thermoplastic resin, and covers one surface of the foamed layer 2.

  The thermoplastic resin is not particularly limited. For example, polyethylene such as high density polyethylene, medium density polyethylene, high pressure method low density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer Examples thereof include a copolymer mainly composed of ethylene such as a polymer, a polypropylene such as a propylene homopolymer, a propylene-ethylene copolymer, a polyester such as polyethylene terephthalate, and a polyamide. Among them, when used as a packaging material, low temperature heat sealability and heat seal strength are required, so polyethylene is preferable, and linear low density polyethylene is more preferable.

  The thickness of the solid layer 3 can be determined in consideration of the use of the laminated film 1, the thickness of the foamed layer 2, etc., for example, preferably 20 to 60 μm, more preferably 30 to 60 μm, and further preferably 40 to 60 μm. . If the thickness of the solid layer 3 is 20 μm or more, it is possible to prevent the solid layer 3 from opening and forming a through-hole in the laminated film 1 following the formation of the opening 22 of the foamed layer 2, and 60 μm or less. If so, the flexibility of the laminated film 1 is ensured.

(Production method)
As a method for producing the laminated film 1 of the present embodiment, for example, the foamable mixture and the non-foamable mixture are coextruded and the foamable mixture is foamed to form the foamed layer 2. One that forms the solid layer 3 made of a non-foaming mixture on one side is mentioned. The foamable mixture is a resin mixture containing a polyolefin resin and a foaming agent, and the non-foamable mixture is a resin mixture containing a thermoplastic resin.
In order to form the foam layer 2 and the solid layer 3, it is preferable to apply inflation film molding.

Examples of the foaming agent include azo compounds such as azodicarbonamide, barium azocarboxylate, azobisisobutyronitrile, nitroso compounds such as N, N′-dinitrosopentamethylenetetramine, and hydrazine compounds such as hydrazocarbonamide. , P-toluenesulfonyl hydrazide, organic chemical blowing agents that generate nitrogen gas such as hydrazide compounds such as p, p'-oxy-bis (benzenesulfonyl hydrazide); carbonates such as sodium hydrogen carbonate, ammonium carbonate, ammonium hydrogen carbonate Inorganic chemical blowing agents that generate gas; lower aliphatic hydrocarbon compounds such as propane, n-butane, i-butane, n-pentane, i-pentane, and hexane; alicyclic hydrocarbon compounds such as cyclobutane and cyclopentane ; Aromatic carbonization such as benzene, toluene, xylene Elemental compounds; lower aliphatic monohydric alcohol compounds such as methanol and ethanol, lower aliphatic ketone compounds such as acetone and methyl ethyl ketone, and low-boiling halogenated hydrocarbon compounds such as chloromethyl, chloroethyl and 1-chloro-1,1-difluoroethane A physical foaming agent composed of a gas such as argon gas, helium gas, chlorofluorocarbon gas, carbon dioxide gas (carbon dioxide gas) or nitrogen gas; The gas in the present embodiment includes not only a gas state but also a fluid in a subcritical state and a supercritical state.
Among these foaming agents, carbon dioxide gas and nitrogen gas are preferable because they are not toxic and suitable for food applications, and it is particularly preferable to be carbon dioxide gas or nitrogen gas in a supercritical state.
The blending amount of the foaming agent in the foamable mixture can be determined in consideration of the type of polyolefin resin, the desired foaming rate, and the like. For example, 0.01 to 2.0% by mass is preferable, and 0.03 to 1. 5 mass% is more preferable.

In addition, the foamable mixture may include an ethylene-propylene rubber, an elastomer resin such as a styrene thermoplastic elastomer, an adhesive resin such as a modified polyolefin, and a polyester biodegradable resin such as polylactic acid as a resin other than the polyolefin resin. Can be blended.
In addition, the foamable mixture may contain starches, lubricants, pigments, antistatic agents, rust preventives, antibacterial agents, oxygen scavengers, bulking agents, and anti-smudges, as long as the object of the present invention is not impaired. Arbitrary components such as an agent and a burn-in preventing agent can be blended. When blending optional components, the blending amount of the optional components in the foamable mixture is about 0.1 to 50% by mass for starches and about 0.01 to 10% by mass for other optional components. The

  In the non-foaming mixture, starches, lubricants, pigments, antistatic agents, rust preventives, antibacterial agents, oxygen scavengers, extenders, anti-smudge agents, as long as they do not impair the purpose of the present invention, Optional components such as an anti-seizure agent can be blended. When blending optional components, the blending amount of the optional components in the non-foaming mixture is about 0.1 to 50% by mass in the case of starches, and about 0.01 to 10% by mass in the case of other optional components. Is done.

  Examples of the inflation film molding include multilayer inflation film molding using a circular die. In multilayer blown film molding, for example, the foamable mixture is coextruded under the conditions of 150 to 220 ° C. and the non-foamable mixture is 160 to 200 ° C., and the blow ratio is 1.1 to 3.0, the take-off speed is 5.0 to Molding is performed at 20.0 m / min. During this time, the foamable mixture becomes the foamed layer 2 in which the foaming agent is foamed to form bubbles, and the bubbles are broken and communicated to form the communicating bubbles 24. In addition, the non-foamable mixture has a desired thickness according to the blow ratio and the take-off speed, and becomes a solid layer 3 provided on one surface of the foam layer 2. In this way, the laminated film 1 can be obtained.

(Condensation prevention container)
The dew condensation prevention container of the present embodiment is formed with the exposed surface 21 of the laminated film 1, that is, the side surface of the foamed layer 2 as the outside. For example, the solid side surfaces 31 of the two laminated films 1 are opposed to each other on three sides. Examples of the bag include a heat-sealed bag and a bag in which one opening of the laminated film 1 formed into a cylindrical shape is heat-sealed. Further, for example, the outer peripheral surface of a metal container such as a steel can or an aluminum can, a glass container such as a glass bottle, or a resin container such as a plastic bottle is laminated so that the exposed surface 21 is outside. A container provided with the film 1 may be mentioned. Especially, since the metal can, the glass bottle, and the PET bottle which accommodated the low temperature drink are easy to produce dew condensation, the anti-condensation effect is remarkable in the metal can, the glass bottle and the PET bottle.

(Container for food and drink)
The food and drink container of the present embodiment is formed with the exposed surface 21 of the laminated film 1, that is, the side surface of the foamed layer 2 as the outer side. For example, the solid side surfaces 31 of the two laminated films 1 face each other on three sides. And a bag having one opening of the laminated film 1 formed into a cylindrical shape and heat-sealed. Further, for example, the outer peripheral surface of a metal container such as a steel can or an aluminum can, a glass container such as a glass bottle, or a resin container such as a plastic bottle is laminated so that the exposed surface 21 is outside. A container provided with the film 1 may be mentioned. Among these, metal cans, glass bottles, and PET bottles containing high-temperature beverages and foods with a temperature of 55 ° C. or higher have high temperatures and are difficult to handle with bare hands. For this reason, in the container which provided the laminated film 1 in the outer peripheral surface of this container, the suppression effect of body temperature is exhibited notably.

Conventionally, in a container in which a foam in which closed cells are formed is provided on the outer peripheral surface of a metal can or the like, although heat insulation is improved, sufficient condensation prevention has not been achieved.
According to the present embodiment, the foamed layer in which the communication bubbles are formed and the solid layer made of the thermoplastic resin are provided, and the foamed layer side is the exposed surface. Can be prevented. Although the mechanism for preventing this dew condensation is not clear, it is presumed as follows. In the laminated film of the present embodiment, an opening is formed on the exposed surface, and by setting the average diameter of the opening and the opening area ratio within a specific range, the outside air enters and exits the communication bubbles, thereby dewing. It can be prevented.

The laminated film of the present embodiment is excellent in preventing condensation and exhibits a high heat insulating effect due to the bubbles formed in the foam layer. For this reason, it can be used as a general heat insulating material such as a container for storing a hot beverage, a cup for storing a hot beverage, a metal can for storing a high temperature content, and the like. In particular, when it is used for a container for storing high-temperature contents, it can be handled with bare hands more easily than when a conventional foam with closed cells formed is applied to the container, and the effect is remarkable.
Thus, in the food and drink container to which the laminated film of the present embodiment is applied, the mechanism that facilitates handling with bare hands is not clear, but is presumed as follows. In the laminated film of the present embodiment, an opening is formed on the exposed surface, and the surface area is large. Therefore, heat dissipation on the exposed surface is fast, and an increase in surface temperature is suppressed. In addition, since the contact area between the laminate film and the handle is extremely small in the laminated film of the present embodiment compared to a conventional foam or the like in which no opening is formed, it is considered that the sensible temperature is lowered.

In addition, according to the present embodiment, it is possible to obtain a laminated film that is excellent in the effect of preventing dew condensation and the effect of suppressing the sensible temperature without providing a complicated process of bonding the nonwoven fabric.
Furthermore, by making the foamed layer side an exposed surface, it is possible to obtain a design with a non-woven fabric-like texture, and the exposed surface is an uneven surface. Things can be prevented.

[Second Embodiment]
(Laminated film)
The laminated film which concerns on 2nd embodiment of this invention is demonstrated using FIG. 4 below. In addition, the same code | symbol is attached | subjected to the structure same as the laminated | multilayer film 1 (FIG. 1), and the description is abbreviate | omitted. FIG. 4 is a cross-sectional view of the laminated film 100 according to the second embodiment. As shown in FIG. 4, the laminated film 100 is a film in which the bubble reduction portion 120 is partially formed in the foam layer 2 and the print layer 104 is formed on the solid side surface 31.

The bubble reduction part 120 is thinned, the formation of bubbles is sparse, and is more transparent than the other parts of the foam layer 2.
The transparency of the bubble reduction part 120 should just be transparent rather than the other part of the foaming layer 2, and can be determined according to the objective of the display in the exposed surface 21. FIG.
For example, when a graphic or the like is printed on the solid side surface 31, if the transparency of the bubble reduction unit 120 is set so that the appearance of the printed graphic or the like can be easily recognized from the exposed surface 21, the printed graphic or the like is exposed. 21 can be displayed as a pattern.
Further, for example, when information such as a barcode, characters, numbers, etc. is printed on the solid side surface 31, the transparency of the bubble reduction unit 120 should be such that the printed information can be clearly recognized from the exposed surface 21 side. The printed information can be displayed on the exposed surface 21. When the transparency of the bubble reduction unit 120 is increased and information printed on the solid side surface 21 is clearly displayed on the exposed surface 21, the transparency is preferably set so that the barcode can be read.
The transparency of the bubble reduction unit 120 can be adjusted by a combination of the temperature at which the foamed layer 2 is melted, the pressing pressure, the pressing time, and the like.

  The shape of the bubble reduction unit 120 can be determined according to the size of the graphic or character printed on the printing layer 104 and the shape displayed on the exposed surface 21. For example, the shape of the bubble reduction unit 120 is a triangle in plan view, Examples include polygons such as rectangles, circles such as perfect circles and ellipses, figures such as star shapes and leaflet shapes, numbers, letters, and the like.

  If the area of the bubble reduction part 120 is too large, the opening area ratio on the exposed surface 21 becomes too small, or the void ratio of the foamed layer 2 becomes too small. Is insufficient. Therefore, the size of the bubble reduction unit 120 is preferably as small as possible in consideration of the number of prints of the print layer 104 and the like.

The printed layer 104 is printed at least at the position of the bubble reduction unit 120. The print layer 104 is not particularly limited, and may be, for example, a bar code, number, or character printed, or may be a solid print.
For example, when the print layer 104 is configured to print information, the information applied to the solid layer 3 can be read from the exposed surface 121 through the bubble reduction unit 120. For example, when the printing layer 104 is solid, the shape of the bubble reduction unit 120 that is the color of the printing layer 104 can be displayed on the exposed surface 21 as a figure, a character, or the like.

The method for forming the bubble reduction unit 120 is not particularly limited as long as the foam layer 2 is remelted. For example, a pressing die having a convex portion corresponding to the shape of the bubble reduction unit 120 is used, and this pressing die is heated. After that, a method of pressing against the exposed surface 21 (hot pressing), a method of irradiating laser, infrared rays, a method of irradiating ultrasonic waves with an ultrasonic welding apparatus, and the like can be mentioned. Of these, the hot press method is preferred from the viewpoint of productivity and haze control.
As a device for performing the hot press, a known marking device can be used. The engraving device may be an intermittent engraving device using a pressing die provided with a convex portion on a flat plate-like main body, or a pressing device provided with a convex portion on the peripheral surface of a cylindrical main body. It may be a continuous marking device using a mold. From the viewpoint of productivity, it is preferable to use a continuous marking apparatus.
The material of the pressing die can be determined in consideration of the temperature of the pressing die at the time of hot pressing, and examples thereof include metals and heat resistant resins.
The temperature of the pressing die at the time of hot pressing can be determined according to the material of the foam layer 2 and the like, for example, 130 to 250 ° C.
The pressing pressure at the time of hot pressing can be determined according to the material of the foam layer 2, the haze required for the bubble reduction unit 120, and the like, for example, 0.1 to 1.0 MPa.
The pressing time at the time of hot pressing can be determined in consideration of the material of the foam layer 2, the temperature of the pressing die, and the like, and is set to 0.1 to 10 seconds, for example.

(Condensation prevention container)
The dew condensation prevention container of this embodiment is the same as the dew condensation prevention container of the first embodiment.

(Container for food and drink)
The container for food and drink of this embodiment is the same as the container for food and drink of the first embodiment.

Since the exposed surface of the foamed layer has a large number of openings, ink adhesion is uneven and it is difficult to perform clear printing. In addition, the foam layer has a high haze due to the formation of a large number of bubbles, and even if information is printed on a solid side surface or solidly printed, the information and color cannot be displayed on the exposed surface.
According to this embodiment, since the highly transparent bubble reduction part is formed, the information given to the solid side surface can be read from the exposed surface. Alternatively, the solid color of the printed layer can be raised according to the plan view shape of the bubble reduction unit, and a figure, characters, or the like can be displayed on the exposed surface.

The present invention is not limited to the embodiment described above.
In the first to second embodiments, the closed cells 26 are formed in the foamed layer 2. However, in the present invention, it is only necessary that the open cells 24 are formed in the foamed layer 2, and the closed cells 26 are formed. It does not have to be.

Although the first embodiment has a two-layer structure of the foam layer 2 and the solid layer 3, for example, a laminated structure of three or more layers in which another resin layer or a metal layer is provided on the solid side surface 31. It may be said.
Further, for example, the exposed surface 21 and / or the solid side surface 31 may be printed.

In the second embodiment, the print layer 104 is formed on the solid side surface 31. However, for example, the print layer 104 may not be formed. When the printed layer 104 is not formed, the bubble reduction unit 120 can serve as a window except for checking the contents of the dew condensation prevention container and the food and drink container made of the laminated film 100. Alternatively, when the laminated film 100 is provided on the outer peripheral surface of the container, the information printed on the container can be read by the bubble reduction unit 120.
Alternatively, the solid layer 3 may be colored instead of forming the print layer 104. When the solid layer 3 is colored, the shape of the bubble reduction unit 120 that is the color of the solid layer 3 can be displayed on the exposed surface 21 side as a figure or a character.
Examples of the coloring of the solid layer 3 include pigments used for coloring a resin film.

  In 1st-2nd embodiment, although the laminated | multilayer film was manufactured by the inflation film shaping | molding by coextrusion, the manufacturing method of a laminated | multilayer film is not limited to this, For example, a foamable mixture and a non-foamable mixture are used. It may be coextruded with a T-die, or may be stretched after coextrusion.

(Raw materials used)
The polyolefin-based resin used in Examples or Comparative Examples is as follows.
<Polyolefin resin>
Polypropylene (PP): Q100F, MFR; 0.6 g / 10 min, density: 0.88 g / cm ³ , tensile breaking stress: 12 MPa, nominal strain at tensile breaking;> 300%, flexural modulus: 105 MPa, melting point ( DSC method); 142 ° C., manufactured by Sun Allomer Co., Ltd. Low density polyethylene (LDPE): LF128, MFR; 0.25 g / 10 min, density: 0.922 g / cm ³ , tensile breaking stress; −, nominal strain at tensile breaking > 400%, flexural modulus; 260 MPa, melting point (DSC method); 111 ° C., manufactured by Nippon Polyethylene Corporation ・ Linear low density polyethylene (LLDPE): UF421, MFR; 0.9 g / 10 min, density: 0 .925g / cm ^3, the tensile yield stress; 12 MPa, tensile breaking nominal strain;> 400%, flexural modulus; 410 MPa, the melting point (D Method C); 124 ° C., Nippon Polyethylene Co., Ltd., high density polyethylene (HDPE): HF560, MFR; 7.0g / 10 min, density; 0.963 g / cm ^3, the tensile yield stress; 26 MPa, the strain called tensile fracture > 400%, flexural modulus; 1050 MPa, melting point (DSC method); 134 ° C., manufactured by Nippon Polyethylene Co., Ltd.

(Evaluation methods)
<Evaluation of anti-condensation effect>
The dew condensation prevention container prepared in each example was stored in a 5 ° C. cool box for 24 hours, then left in a room temperature (25 ° C., 60% RH) environment, and the surface state of the condensation prevention container was observed after 10 minutes. did.
In the case where no condensation was observed at all, “◯” was indicated. In the case where water droplets were not visually observed, “Δ” was indicated for moisture feeling when touched by hand, and “X” was indicated for water droplets being visually observed.

<Measurement of average diameter and open area ratio of exposed surface>
The exposed surface (foamed layer side surface) of the laminated film obtained in each example was magnified (30 times) with SEM (S-4800, manufactured by Hitachi High-Technologies Corporation). This magnified image was printed, and the unprinted portion (margin portion) was removed to obtain an original image paper. With respect to the obtained original video paper, the area of the exposed surface that was magnified was calculated, and this area was defined as _S0 .
Subsequently, the mass (M ₀ ) of the original video paper was measured with an electronic balance (AEX200B, manufactured by Shimadzu Corporation). Each portion corresponding to the opening of the original video paper was cut out, and the cut paper was used as the opening video paper. The mass of all openings video paper was measured with an electronic balance, the weight of the opening image each paper was M _1.
And the opening area ratio was computed by the following (3) formula.

Open area ratio (%) = (ΣM ₁ ) ÷ M ₀ × 100 (3)
(ΣM ₁ represents the sum of the masses M ₁ of the opening image paper cut from the original video paper.)

Was also calculated the area of each opening (S ₁₎ by the following equation (4).

S ₁ = M ₁ ÷ M ₀ × S ₀ (4)

For the average diameter of the exposed surface, the diameter (R ₁ ) of each opening was calculated by the following formula (5), and the average diameter (R _μ ) was calculated by the following formula (6) based on the calculated R ₁ .

R ₁ = 2 × √ (S ₁ / π) (5)
R _μ = (ΣR ₁ ) ÷ n (6)
(S ₁ is the area of the opening calculated by the above equation (4), ΣR ₁ indicates the sum of the diameters R ₁ of the openings on the exposed surface, and n is the sum of the number of openings on the exposed surface. Is shown.)

<Measurement of porosity>
The laminated film of each example was cut into 10 cm × 10 cm to obtain a test piece, and the mass (W ₀ ) of the test piece was measured with an electronic balance. The thickness of this test piece was measured with a thickness measuring instrument (G-6C, manufactured by Ozaki Manufacturing Co., Ltd.), and the volume (V ₀ ) of the test piece was calculated. Further, the thickness of the solid layer was calculated from the molding conditions (discharge amount, film forming width, take-off speed) and the density of the non-foaming mixture, and the volume (V _s ) of the solid layer was calculated. The thickness of the solid layer was calculated by the following equation (7).

Solid layer thickness (cm) = Discharge amount of non-foaming mixture (g / min) ÷ {Solid layer film forming width (cm) × Taking speed (cm / min) × Non-foaming mixture density (g / cm ³ )} ... (7)

A vacuum constant-temperature dryer (DP23, DP23, 25 ° C.) immersed in an alcohol solution (ethanol / isopropyl alcohol mixture, density: 0.792 g / cm ³ , AP-7 (manufactured by Nippon Alcohol Sales Co., Ltd.)) The pressure was reduced to −0.09 MPa in Yamato Kagaku Co., Ltd., and the bubbles of the test piece were impregnated with an alcohol solution.
The inside of the vacuum constant temperature dryer was decompressed to -0.09 MPa in 20 seconds, held for 1 second, and then returned to normal pressure in 10 seconds. Subsequently, the test piece was taken out from the alcohol solution, and the taken out test piece was passed between two metal rolls (mass: 60 g / piece) having a width of 30 cm to remove the alcohol solution adhering to the surface of the test piece. Thus, a liquid-impregnated test piece in which bubbles were impregnated with an alcohol liquid was obtained. In addition, in the exposed surface of this liquid impregnation test piece, it was in the state where the alcohol liquid was impregnated also into the opening part.
The mass (W _a ) of the obtained liquid-impregnated test piece was measured with an electronic balance, and the porosity (ε) was calculated by the following equation (8).

ε (%) = {(W _a −W ₀ ) ÷ 0.792} ÷ (V ₀ −V _s ) × 100 (8)

<Measurement of bulk density>
The laminated film of each example was cut to 10 cm × 10 cm to obtain a test piece, and the volume of the test piece (V ₀ ) and the volume of the solid layer (V _s ) were calculated in the same manner as the above “<Measurement of porosity”. did. And the volume ( _Vf ) of the foaming layer was computed by subtracting the volume of a solid layer from the volume of a test piece. Further, the mass (W ₀ ) of the test piece was measured with an electronic balance, and the mass (W _s ) of the solid layer was calculated by the following equation (9). Furthermore, the mass (W _f ) of the foam layer was calculated from the following equation (10) from the mass (W ₀ ) of the test piece and the mass (W _s ) of the solid layer obtained by the equation (9).

W _s = V _s × density of non-foaming mixture (9)
W _f = W ₀ −W _s (10)

From the calculated volume (V _f ) of the foamed layer and the mass (W _f ) of the foamed layer, the bulk density (ρ) of the foamed layer was calculated by the following formula (11).

ρ = W _f ÷ V _f (11)

<Appearance evaluation>
The exposed surface of the laminated film obtained in each example was visually observed, and the appearance was evaluated according to the following criteria.
○: The opening cannot be visually recognized, or the opening is small and unnoticeable, and the entire exposed surface is uniform.
(Triangle | delta): Although the opening part which can be visually recognized exists locally, the whole exposed surface is uniform.
X: A visually recognizable opening exists, and cracks and defects in which adjacent openings are connected are recognized, and the entire exposed surface cannot be recognized as uniform.

<Measurement of surface temperature>
After pouring 300 mL of 65 degreeC water into the container for food and drink of each case, it covered, and was left still for 60 seconds after that. After standing, the thermocouple portion of a contact thermometer (AM-2001, manufactured by Anritsu Keiki Co., Ltd.) was brought into contact with and fixed to the surface of the food and drink container (exposed surface of the label). The display temperature 30 seconds after the contact of the thermocouple portion was read.

<Evaluation of the effect of suppressing the temperature of experience>
The container for food and drink of each example was capped after pouring 300 mL of water at 65 ° C. The container for food and drink was stored in a dryer at 65 ° C. for 1 hour. After storage, the sample was taken out into a room at 25 ° C. and immediately held by hand, and the time until it was too hot to hold was measured. The effect of suppressing the sensory temperature was evaluated by classifying the average value of 10 monitors according to the following evaluation criteria.
≪Evaluation criteria≫
◯: Over 10 seconds Δ: Over 5 seconds, 10 seconds or less ×: 5 seconds or less

<Evaluation of readability>
A barcode reader (AC-880, manufactured by Apok Co., Ltd.) was brought into contact with the exposed surface, and the barcode printed on the solid side layer was read. The case where the barcode was properly read by the reader was “◯”, and the case where the barcode was not properly read was “x”.

Example 1
Inflation film forming machine A equipped with a circular die (extruder for foamable mixture: φ75 mm, L / D32, extruder for non-foamable mixture: φ50 mm, L / D28, lip diameter: φ300 mm, lip clearance: 0.8 mm) , 40 parts by mass of PP, 60 parts by mass of LDPE, 1.0 part by mass of sodium hydrogencarbonate, and a non-foamable mixture of LLDPE were coextruded under the condition of a die temperature of 200 ° C. to form an inflation film. The conditions for forming the inflation film were blow ratio: 2.3 and take-up speed 7.0 m / min. At this time, the foamable mixture was foamed to obtain a laminated film including a foam layer having a thickness of 140 μm and a solid layer having a thickness of 50 μm.

  The obtained laminated film was wound around the outer periphery of an aluminum can containing a liquid so that the exposed surface (side surface of the foam layer) was on the outside, and a dew condensation prevention container was produced. About this dew condensation prevention container, while evaluating a dew condensation prevention effect, the external appearance evaluation of the laminated film was performed, and the result is shown in Table 1.

(Example 2)
A laminated film (foamed layer: 150 μm, solid layer: 50 μm) was obtained under the same conditions as in Example 1 except that the die temperature was 210 ° C.
Using the obtained laminated film, a dew condensation prevention container was produced in the same manner as in Example 1, the condensation prevention effect was evaluated, and the appearance of the laminated film was evaluated. The evaluation results are shown in Table 1.

(Example 3)
A laminated film (foamed layer: 130 μm, solid layer: 50 μm) was obtained under the same conditions as in Example 1 except that the die temperature was 190 ° C.
Using the obtained laminated film, a dew condensation prevention container was produced in the same manner as in Example 1, the condensation prevention effect was evaluated, and the appearance of the laminated film was evaluated. The evaluation results are shown in Table 1.

Example 4
A laminated film (foamed layer: 125 μm, solid layer: 50 μm) was obtained under the same conditions as in Example 1 except that sodium bicarbonate was changed to 0.8 part by mass.
Using the obtained laminated film, a dew condensation prevention container was produced in the same manner as in Example 1, the condensation prevention effect was evaluated, and the appearance of the laminated film was evaluated. The evaluation results are shown in Table 1.

(Example 5)
A laminated film (foamed layer: 110 μm, solid layer: 32 μm) was obtained under the same conditions as in Example 1 except that the die temperature was 210 ° C. and the take-up speed was 10.9 m / min.
Using the obtained laminated film, a dew condensation prevention container was produced in the same manner as in Example 1, the condensation prevention effect was evaluated, and the appearance of the laminated film was evaluated. The evaluation results are shown in Table 1.

(Comparative Example 1)
Using an inflation film molding machine A, a foamable mixture composed of 100 parts by weight of LDPE and 1.0 part by weight of azodicarbonamide was extruded under the condition of a die temperature of 200 ° C., and a single layer composed of closed cells having a foaming ratio of 1.3 times A foam film was obtained. When the surface of the obtained foamed film was observed with an SEM, no opening was formed (FIG. 5). The obtained foamed film was wound around the outer periphery of an aluminum can containing a liquid to produce a dew condensation prevention container. About this dew condensation prevention container, while evaluating a dew condensation prevention effect, the external appearance evaluation of a foamed film was performed, and the evaluation result is shown in Table 1.

(Comparative Example 2)
A laminated film (foamed layer: 115 μm, solid layer: 50 μm) was obtained under the same conditions as in Example 1 except that sodium hydrogen carbonate was changed to 0.6 parts by mass.
Using the obtained laminated film, a dew condensation prevention container was produced in the same manner as in Example 1, the condensation prevention effect was evaluated, and the appearance of the laminated film was evaluated. The evaluation results are shown in Table 1.

(Comparative Example 3)
A laminated film (foamed layer: 90 μm, solid layer: 26 μm) was obtained under the same conditions as in Example 1 except that the die temperature was 215 ° C., the take-up speed was 10.9 m / min, and the blow ratio was 2.8.
Using the obtained laminated film, a dew condensation prevention container was produced in the same manner as in Example 1, the condensation prevention effect was evaluated, and the appearance of the laminated film was evaluated. The evaluation results are shown in Table 1.

As shown in Table 1, in Examples 1 to 5 using the laminated film of the present invention, the effect of preventing condensation was observed. In addition, in Examples 1 to 5, the appearance evaluation was “◯” or “Δ”, and a good appearance was maintained.
On the other hand, in Comparative Examples 1 and 2, adhesion of water droplets due to condensation was observed with the naked eye. In Comparative Example 3, although the condensation evaluation was “Δ”, the appearance was impaired.
FIG. 6 is a photograph (20 times) after standing for 10 minutes of the dew condensation prevention container of Example 1. Reference numeral 50 indicates the surface of the metal can, and reference numeral 52 indicates water droplets generated on the surface of the metal can. FIG. 7 is a photograph (20 times) of the dew condensation prevention container of Comparative Example 1 after standing for 10 minutes. Reference numeral 70 indicates the surface of the foamed film obtained in Comparative Example 1, and reference numeral 72 indicates the foamed film surface 70. Shows water droplets generated.
As shown in FIG. 6, the dew condensation prevention container of the present invention had dew condensation on the metal can surface 50 not provided with the laminated film of the present invention, but dew condensation on the surface provided with the laminated film of the present invention, that is, the exposed surface 21. Did not occur. On the other hand, in the dew condensation prevention container using the foam film of Comparative Example 1, dew condensation occurred on the foam film surface 70 as shown in FIG.

(Example 6)
Inflation film forming machine A equipped with a circular die (extruder for foamable mixture: φ75 mm, L / D32, extruder for non-foamable mixture: φ50 mm, L / D28, lip diameter: φ300 mm, lip clearance: 0.8 mm) , 40 parts by weight of PPPE, 40 parts by weight of LDPE, 20 parts by weight of HDPE, 1.0 part by weight of sodium bicarbonate, and a non-foamable mixture of LLDPE at a die temperature of 210 ° C. Molded. The conditions for forming the inflation film were blow ratio: 2.3 and take-up speed 7.0 m / min. At this time, the foamable mixture was foamed to obtain a laminated film including a foam layer having a thickness of 140 μm and a solid layer having a thickness of 50 μm.
A barcode was printed on the solid side of the resulting laminated film. Next, the bar code position was hot-pressed at 0.3 MPa, 140 ° C. for 3 seconds to form a bubble reduction part, and then cut into a strip of 8 cm × 22 cm to form a label. This label was wound around the outer periphery of a 300 mL capacity aluminum can so that the exposed surface (side surface of the foamed layer) was on the outside, to produce a food and drink container. About this food / beverage container, the suppression effect of a sensible temperature and evaluation of readability were performed, and the result is shown in Table 2.

(Example 7)
Inflation film forming machine B equipped with a circular die (extruder for foamable mixture: φ55 mm, L / D28, extruder for non-foamable mixture: φ50 mm, L / D28, lip diameter: φ150 mm, lip clearance: 0.8 mm) , 40 parts by mass of PP, 60 parts by mass of LDPE, 1.0 part by mass of sodium hydrogencarbonate, and a non-foamable mixture of LLDPE were coextruded under the condition of a die temperature of 200 ° C. to form an inflation film. The conditions for blown film molding were blow ratio: 2.0 and take-up speed 15.0 m / min. At this time, the foamable mixture was foamed to obtain a laminated film having a foam layer having a thickness of 85 μm and a solid layer having a thickness of 35 μm, an opening area ratio of 46.2%, and an average aperture of 252 μm.
A barcode was printed on the solid side of the laminated film. Next, the bar code position was hot-pressed at 0.3 MPa, 140 ° C. for 3 seconds to form a bubble reduction part, and then cut into a strip of 8 cm × 22 cm to form a label. This label was wound around the outer periphery of a 300 mL capacity aluminum can so that the exposed surface (side surface of the foamed layer) was on the outside, to produce a food and drink container. About this food / beverage container, the suppression effect of a sensory temperature and evaluation of readability are performed, and the result is shown in Table 2.

(Comparative Example 4)
A laminated film having a foam layer having a closed cell (thickness: 140 μm) and a solid PP layer (thickness: 50 μm) was used. A barcode is printed on the solid side of this laminated film, and a bubble reduction part is formed at the barcode position by hot pressing at 0.3 MPa, 140 ° C. for 5 seconds, and then cut into a strip of 8 cm × 22 cm. And made a label. This label was wound around the outer periphery of a 300 mL capacity aluminum can so that the exposed surface (side surface of the foamed layer) was on the outside, to produce a food and drink container. About this food / beverage container, the suppression effect of a sensible temperature and evaluation of readability were performed, and the result is shown in Table 2.

(Comparative Example 5)
A bar code was printed on one side of a PP film (non-foamed, thickness: 40 μm), and a non-woven fabric of 18 g / m ² was bonded to the side on which the bar code was printed to form a laminated film. This laminated film was cut into a strip of 8 cm × 22 cm to form a label. This label was wound around the outer periphery of a 300 mL capacity aluminum can so that the nonwoven fabric was on the outside, and a food and drink container was prepared. About this food / beverage container, the suppression effect of a sensible temperature and evaluation of readability were performed, and the result is shown in Table 2.

(Comparative Example 6)
After printing a barcode on one side of a foam film having a closed cell (thickness: 120 μm), forming a bubble reduction part at the barcode position by applying a heat press at 0.3 MPa, 140 ° C. for 3 seconds, The label was cut into strips of 8 cm × 22 cm. This label was wound around the outer periphery of a 300 mL capacity aluminum can so that the barcode printing surface was on the inside, thereby preparing a food and drink container. About this food / beverage container, the suppression effect of a sensible temperature and evaluation of readability were performed, and the result is shown in Table 2.

(Comparative Example 7)
A barcode was printed on one side of a PP film (non-foamed, thickness: 200 μm) and cut into a strip of 8 cm × 22 cm to form a label. This label film was wound around the outer periphery of a 300 mL capacity aluminum can so that the barcode printing surface was on the inside, thereby preparing a food and drink container. About this food / beverage container, the suppression effect of a sensible temperature and evaluation of readability were performed, and the result is shown in Table 2.

(Comparative Example 8)
A barcode was printed on one side of a PP film (non-foamed, thickness: 40 μm) and cut into a strip of 8 cm × 22 cm to form a label. This label film was wound around the outer periphery of a 300 mL capacity aluminum can so that the printed surface was inside, and a food and drink container was prepared. About this food / beverage container, the suppression effect of a sensible temperature and evaluation of readability were performed, and the result is shown in Table 2.

(Comparative Example 9)
A bar code was printed on one side of a PP film (non-foamed, thickness: 40 μm), and a non-woven fabric of 18 g / m ² was bonded to the side on which the bar code was printed to form a laminated film. This laminated film was cut into a strip of 8 cm × 22 cm to form a label. The label was wound around the outer periphery of a 300 mL aluminum can so that the PP film surface was on the outside, and a food and drink container was prepared. About this food / beverage container, the suppression effect of a sensible temperature and evaluation of readability were performed, and the result is shown in Table 2.

(Comparative Example 10)
An aluminum can with a capacity of 300 mL that does not wrap around the label is used as a food and drink container, and the effect of suppressing the sensory temperature and the evaluation of readability are evaluated.

 FIG. 8 shows an enlarged photograph of the laminated film used in Example 6. FIG. 8 is a photograph of the exposed surface of Example 6 taken with a CCD camera (AMD413T, manufactured by Amano Electronics Corporation) (magnification: 58 times). As shown in FIG. 8, it can be seen that this laminated film has a broad state in which the opening diameter of the opening formed on the exposed surface is about several μm to 2 mm.

As shown in Table 2, Examples 6 to 7 to which the present invention was applied had a surface temperature of 53.5 to 54.0 ° C. In Comparative Examples 4 and 6 in which the foam layer is made of closed cells, and Comparative Examples 7 to 8 in which the non-foamed PP film is a single layer, the surface temperature is 56.6 to 56.7 ° C. The temperature was higher than 6-7. Moreover, the comparative examples 5 and 9 which used the nonwoven fabric instead of the foamed layer had a surface temperature of 53.3 to 53.7 ° C. and were substantially equivalent to those of Examples 6 to 7.
In all of Examples 6 to 7 to which the present invention was applied, the readability was “◯”, and the effect of suppressing the sensible temperature was “◯”.
On the other hand, in Comparative Example 4 in which the foam layer is made of closed cells, and in Comparative Example 6 in which the foam layer is made of closed cells and the solid layer is not provided, the readability is “◯” by providing the bubble reduction part. However, the effect of suppressing the sensory temperature was “Δ”. In Comparative Example 5 in which the nonwoven fabric was provided in place of the foamed layer, the reading effect was “x” although the effect of suppressing the sensible temperature was “◯”. Moreover, although the comparative example 9 which provided the nonwoven fabric in place of the foaming layer and provided the label so that the nonwoven fabric is inside, the readability was “◯”, but the effect of suppressing the sensible temperature was “△”. . Furthermore, Comparative Examples 7 and 8 using a label without a foam layer and Comparative Example 10 without a label itself had a readability of “◯”, but the effect of suppressing the sensible temperature was “×”. there were.
From the above results, it was found that by applying the present invention, a laminated film excellent in the effect of suppressing the sensible temperature can be obtained. In addition, it was found that readability could be secured by a simple process called hot pressing.

DESCRIPTION OF SYMBOLS 1,100 Laminated film 2 Foam layer 3 Solid layer 21 Exposed surface 22 Opening part 23 Air bubble 24 Communication bubble 104 Print layer 120 Bubble reduction part

Claims (13)

A foamed layer of polyolefin-based resin in which open cells are formed, and a solid layer containing a thermoplastic resin provided on one surface of the foamed layer;
A laminated film, wherein the foamed layer is an exposed surface, the average diameter of the exposed bubbles is 200 to 500 μm, and the open area ratio of the bubbles is 30 to 80%.   The laminated film according to claim 1, wherein the foam layer has a porosity of 30 to 70% by volume. The laminated film according to claim 1 or 2, wherein the foam layer has a bulk density of 0.20 to 0.60 g / cm ³ .   The laminated film according to claim 1, wherein the polyolefin-based resin includes polypropylene.  The laminated film according to any one of claims 1 to 4, wherein a bubble reducing portion is partially formed in the foam layer.  The laminated film according to claim 5, wherein the solid layer is printed at a position of the bubble reduction portion.   While coextruding a foamable mixture containing a polyolefin-based resin and a foaming agent and a non-foamable mixture containing a thermoplastic resin, the foamable mixture is foamed to form the foamed layer. The method for producing a laminated film according to claim 1, wherein a solid layer made of a non-foamable mixture containing a thermoplastic resin is formed on one surface.   While coextruding a foamable mixture containing a polyolefin-based resin and a foaming agent and a non-foamable mixture containing a thermoplastic resin, the foamable mixture is foamed to form the foamed layer. A solid layer made of a non-foamable mixture containing a thermoplastic resin is formed on one surface, and then the foamed layer is partially melted to form the bubble reduction part. 6. A method for producing a laminated film according to 6.   The method for producing a laminated film according to claim 7 or 8, wherein the foam layer and the solid layer are formed by inflation film molding.   A dew condensation prevention container, wherein the laminated film according to any one of claims 1 to 6 is molded so that the foamed layer is on the outside.   The dew condensation prevention container according to claim 10, wherein the laminated film is provided on an outer peripheral surface of a metal, glass or resin container.   A container for food and drink, wherein the laminated film according to any one of claims 1 to 6 is molded so that the foamed layer is on the outside.   The container for food and drink according to claim 12, wherein the laminated film is provided on an outer peripheral surface of a metal, glass or resin container.