JP5945500B2 - Multi-layer sheet for insulated paper container, insulated paper container, and manufacturing method - Google Patents

Description

  The present invention relates to a multilayer sheet for insulated paper containers, a insulated paper container, and a method for producing them.

  Various heat-insulating containers are used as containers for instant noodles in cups and containers for hot drinks provided from fast food stores and vending machines. A foamed polystyrene container is excellent in heat insulation, but is bulky, inferior in printability, easily broken, and difficult to dispose of waste. Foamed polystyrene containers are not suitable for storing, transporting, cooking, etc. for food such as instant noodles.

  In recent years, insulated paper containers have been developed and are widely used as containers for instant noodles. A body member of a heat insulating paper container is generally a layer in which a low melting point thermoplastic resin layer is provided on one side of a paper base material such as a cup base paper, and a relatively high melting point thermoplastic resin layer is provided on the other side. It is formed from a multilayer sheet having a configuration. When the multilayer sheet itself or a container in which the multilayer sheet is disposed as a body member is heated to a temperature exceeding the melting point of the low-melting thermoplastic resin, moisture contained in the paper base material is evaporated and heated and evaporated. The thermoplastic resin layer having a low melting point is foamed by moisture, and the foamed thermoplastic resin layer functions as a heat insulating layer.

  By controlling the foaming temperature or the like, water vapor is volatilized from the other surface of the paper substrate without substantially foaming the high melting point thermoplastic resin layer and by the high melting point thermoplastic resin layer. While preventing, the low melting point thermoplastic resin layer can be foamed. Since the heat insulating paper container having such a layer structure has higher strength than foamed polystyrene, it is difficult for cracks to occur. The low-melting point thermoplastic resin layer before foaming or the foamed thermoplastic resin layer often has good printability. The insulated paper container is excellent in preservability of contents such as food. Instant noodles packaged in an insulated paper container can be easily cooked by pouring hot water into the container. Further, since the heat insulating paper container includes a paper base material as a main layer, the waste can be incinerated. Thus, the insulated paper container has many advantages.

  Conventionally, various proposals have been made regarding insulated paper containers. For example, in Japanese Patent Application Laid-Open No. 57-110439 (Patent Document 1), in a heat insulating paper container composed of a container body member and a bottom plate member, at least one side wall surface of the container body member is a foam insulation of a thermoplastic synthetic resin film. And the other wall surface of the container body member is provided with a heat insulating paper container coated or laminated with either a thermoplastic synthetic resin film, a foam heat insulating layer of the resin film or an aluminum foil. Proposed.

  In Patent Document 1, a paper container in which a low density polyethylene (LDPE) film is laminated or coated on at least one side of a base paper is heated at 110 to 200 ° C. for 20 seconds to 4 minutes, and the moisture contained in the base paper A method for producing a heat insulating paper container in which the low density polyethylene film is foamed to form a foam heat insulating layer is disclosed. In an example of Patent Document 1, there is a cup container including a barrel member having a layer configuration of “LDPE foam heat insulation layer / base paper / LDPE foam heat insulation layer” and “medium-low pressure polyethylene layer / base paper / LDPE foam heat insulation layer”. It is shown.

  Japanese Patent Application Laid-Open No. 5-42929 (Patent Document 2) discloses a paper container composed of a bottom plate member and a body member, and a thermoplastic resin having a low melting point on at least one wall surface of the body member from the surface side of the paper. A two-layer structure heat insulating film comprising a foam inner layer and a non-foamed outer layer of a thermoplastic resin having a melting point higher than that of the thermoplastic resin is deposited, and another single-layer thermoplastic is provided on the outer wall surface of the body portion. A paper container having a structure in which a resin film is applied has been proposed. The foamed inner layer of the low melting point thermoplastic resin is foamed by heating and evaporation of moisture contained in the paper constituting the container.

  In the paper container of Patent Document 2, since the resin layer has a two-layer structure with different melting points, sufficient heat insulation is obtained by foaming the inner layer, and the outer layer does not foam and maintains the original smooth surface. Is done. In Patent Document 2, in order to form a foamed inner layer and prevent defects such as pinholes and blisters in the outer layer, the difference in melting point or softening point between the inner layer film and the outer layer film forming the foamed inner layer is It is disclosed that the temperature is preferably 5 ° C. or higher.

  The heat-insulating paper container is printed to improve the appearance of the container and to provide product identification. JP-A-11-189279 (Patent Document 3) laminates a low-melting thermoplastic synthetic resin film that is foamed by heat treatment on the outer wall surface of a base paper of a container body member of a heat-insulating paper container, It describes that white tuning ink is applied as a base to the surface of a low-melting thermoplastic synthetic resin film, and further, a pattern, design, character, barcode, or the like is applied to the upper surface of the tuning ink with the tuning ink.

  Japanese Patent Application Laid-Open No. 2006-168770 (Patent Document 4) discloses a low-melting-point heat having a high-melting point thermoplastic synthetic resin layer on one side of a base paper and a printed layer of a single color ink on the other side. Using a base paper provided with a plastic synthetic resin layer, a cylindrical body member having an upper and lower opening is molded so that the printed layer is on the outside, and a bottom member is integrated with the body member to form a container body. A method for producing a heat-insulating foamed paper container in which a heat insulating layer is formed on the outer surface of a container by printing a design such as letters and figures on the side surface and then foaming a low-melting thermoplastic synthetic resin layer by heating the container body Is described.

  These conventional heat-insulating paper container body members are laminated with a high-melting point thermoplastic synthetic resin on the inner wall surface of the base paper, and a low-melting point thermoplastic synthetic resin is laminated on the outer wall surface of the base paper. Since ink is applied and printed on the upper surface and then heat-treated to foam the low-melting point thermoplastic synthetic resin, the printed characters and colors may be lost. In addition, since the outer surface of the container becomes uneven due to foaming, it is not glossy, easy to be scratched, easy to get dirty, and has poor hygiene properties such as poor solvent resistance and printed ink may fall off. Problems from the viewpoint have also been pointed out, and it has been desired to improve without impairing the productivity of the insulated paper container such as the efficiency of the heat sealing process.

JP-A-57-110439 JP-A-5-42929 Japanese Patent Laid-Open No. 11-189279 JP 2006-168770 A

  An object of the present invention is to provide a printed sheet and a multilayer sheet for a heat insulating paper container provided with a paper base material, a thermoplastic resin layer, and a foamable low melting point thermoplastic resin layer. And it is providing the multilayer sheet | seat for insulated paper containers excellent in scratch resistance and hygiene, the insulated paper container, and those manufacturing methods.

  As a result of diligent research to solve the above problems, the present inventors can solve the problems by providing a simple configuration in which a non-foaming low melting point thermoplastic resin layer is provided on the upper surface of the printing layer. I found what I could do and completed the present invention.

  That is, according to the present invention, the low-melting point thermoplastic resin layer (A), the printing layer (B), the foamable low-melting point thermoplastic resin layer (C), the paper substrate (D), and the thermoplastic resin layer ( E) is provided in this order, and a multilayer sheet for insulated paper containers is provided.

According to the present invention, as an embodiment, the following multilayer sheets for insulated paper containers (1) to (8) are provided.
(1) The printing layer (B) has a pattern printing layer (B1) adjacent to the low melting point thermoplastic resin layer (A) and a solid printing layer (B2) on the opposite side of the low melting point thermoplastic resin layer (A). The multilayer sheet for insulated paper containers as described above.
(2) The multilayer sheet for insulated paper containers as described above, wherein the foamable low melting point thermoplastic resin layer (C) is foamed by evaporation of moisture contained in the paper substrate (D).
(3) The difference in melting point between the thermoplastic resin forming the low melting thermoplastic resin layer (A) and the foamable low melting thermoplastic resin layer (C) is less than 5 ° C. Multi-layer sheet for insulated paper containers.
(4) The above-mentioned heat insulating paper product, wherein the thermoplastic resin forming the low melting point thermoplastic resin layer (A) and the thermoplastic resin forming the foamable low melting point thermoplastic resin layer (C) are different thermoplastic resins. Multi-layer sheet for containers.
(5) The multilayer for a heat insulating paper container as described above, wherein the low melting point thermoplastic resin layer (A), the foamable low melting point thermoplastic resin layer (C) and the thermoplastic resin layer (E) are polyolefin. Sheet.
(6) The multilayer sheet for a heat insulating paper container as described above, wherein the low-melting-point thermoplastic resin layer (A) is formed from a thermoplastic resin containing a matting agent.
(7) The multilayer sheet for a heat-insulated paper container, comprising a barrier layer (F) between the paper substrate (D) and the thermoplastic resin layer (E).
(8) The multilayer sheet for insulated paper containers as described above, wherein the barrier layer (F) is laminated with one or both of the paper substrate (D) and the thermoplastic resin layer (E).

  According to the present invention, the low-melting point thermoplastic resin layer (A), the printing layer (B), the thermoplastic resin layer (E), the paper substrate (D), and the foamable low-melting point thermoplastic resin layer ( C) is provided in this order, and a multilayer sheet for insulated paper containers is provided.

And according to this invention, the printing of a multilayer sheet | seat provided with a printing layer (B), the foamable low melting-point thermoplastic resin layer (C), a paper-made base material (D), and a thermoplastic resin layer (E). Provided is a method for producing a multilayer sheet for insulated paper containers, comprising a step of melt-coating a low-melting point thermoplastic resin on the surface of the layer (B) to form a low-melting point thermoplastic resin layer (A) Is done.

Furthermore, according to this invention, the manufacturing method of the multilayer sheet | seat for insulated paper containers of the following (i)-(iii) is provided as an embodiment.
(I) The process of forming a printing layer (B) on the surface of a multilayer sheet provided with the foamable low melting point thermoplastic resin layer (C), the paper base material (D), and the thermoplastic resin layer (E) in this order. The manufacturing method of the said multilayer sheet for insulated paper containers containing.
(Ii) A low-foamable surface on the opposite side of the thermoplastic resin layer (E) of the paper substrate (D) of the multilayer sheet comprising the paper substrate (D) and the thermoplastic resin layer (E) The manufacturing method of the said multilayer sheet for insulated paper containers including the process of forming melting | fusing point thermoplastic resin layer (C).
(Iii) By including a step of laminating the barrier layer (F) with one or both of the paper substrate (D) and the thermoplastic resin layer (E) by adhesion, the paper substrate (D) and the thermoplastic layer are included. The manufacturing method of the said multilayer sheet for insulated paper containers which shall be equipped with a barrier layer (F) between resin layers (E).

  Furthermore, according to this invention, the member formed from the said multilayer sheet for insulated paper containers, especially the insulated paper container provided with a trunk | drum member or a bottom member is provided.

  And according to this invention, the manufacturing method of the said insulated paper container including the process of heat-sealing the edge part of the said multilayer sheet for insulated paper containers is provided.

  According to the present invention, the low-melting point thermoplastic resin layer (A), the printing layer (B), the foamable low-melting point thermoplastic resin layer (C), the paper substrate (D), and the thermoplastic resin layer (E). A multilayer sheet for insulated paper containers characterized by comprising a printed layer, a paper substrate, a thermoplastic resin layer, and a foamable low-melting point thermoplastic resin layer. In the multi-layer sheet, there is an effect that it is possible to provide a heat-insulated paper container having a clear print, a beautiful surface, and excellent scratch resistance and hygiene. In addition, the multilayer sheet for insulated paper containers has the unexpected effect of being excellent in low-temperature sealing properties.

  Moreover, according to this invention, the printing of a multilayer sheet provided with a printing layer (B), the foamable low melting-point thermoplastic resin layer (C), a paper-made base material (D), and a thermoplastic resin layer (E). A method for producing a multilayer sheet for insulated paper containers, comprising a step of melt-coating a low-melting point thermoplastic resin on a surface of a layer (B) to form a low-melting point thermoplastic resin layer (A). By this, it is a multilayer sheet for insulated paper containers comprising a printing layer, a foamable low-melting point thermoplastic resin layer, a paper base material and a thermoplastic resin layer, the printing is clear and the surface is beautiful, And the effect that the multilayer sheet | seat for insulated paper containers excellent in scratch resistance and hygiene can be manufactured easily is show | played.

  Furthermore, according to the present invention, a printed layer and a low melting point capable of foaming by being a member formed from the multilayer sheet for a heat insulating paper container, particularly a heat insulating paper container provided with a trunk member or a bottom member. Insulated paper containers provided with a thermoplastic resin layer, a paper base material, and a thermoplastic resin layer are provided with a thermally insulated paper container having a clear print, a beautiful surface, and excellent scratch resistance and hygiene. An effect is produced.

  In addition, according to the present invention, there is provided a printed layer and a foamable low-pressure by the manufacturing method of the insulating paper container including the step of heat-sealing the end of the multilayer sheet for the insulating paper container. Insulated paper containers equipped with a melting point thermoplastic resin layer, a paper base material and a thermoplastic resin layer, easily produce insulated paper containers with clear printing, beautiful surface, and excellent scratch resistance and hygiene. The effect that it can be done is produced.

FIG. 1 is a cross-sectional view showing an embodiment of a heat insulating paper container including a member formed from the multilayer sheet for heat insulating paper containers of the present invention. 2 is an enlarged cross-sectional view of a portion (Y portion) of the body member (a) of the insulated paper container of FIG.

  The multilayer sheet for insulated paper containers of the present invention comprises a low-melting point thermoplastic resin layer (A), a printing layer (B), a foamable low-melting point thermoplastic resin layer (C), a paper base material (D), and a heat A multilayer paper sheet for a heat insulating paper container provided with a plastic resin layer (E), and as shown in FIG. 1, a heat insulating paper container including a trunk member or a bottom member formed from the multilayer paper sheet for a heat insulating paper container is manufactured. can do. In addition, as shown in FIG. 2, for example, as shown in FIG. 2, the body member formed from the multilayer sheet for a heat insulating paper container is a low melting point thermoplastic resin layer (A), a printing layer (B), a foamable low melting point thermoplastic. It is a trunk | drum member formed from the multilayer sheet | seat for insulated paper containers provided with a resin layer (C), a paper-made base material (D), and a thermoplastic resin layer (E) in this order.

1. Paper base material (D)
The paper substrate (D) provided in the multilayer sheet for a heat-insulating paper container of the present invention is not particularly limited, and generally, a paper substrate used for a heat-insulating paper container can be used. For example, wood pulp paper, rayon paper, synthetic pulp paper, synthetic fiber paper, inorganic fiber paper, inorganic powder paper, etc. can be used. Further, as wood pulp paper, fine paper, kraft paper, bleached kraft paper Corrugated base paper, white paperboard, glassine paper, Japanese paper, etc. can be used, and it may be coated paper (coated paper) or non-coated paper. Polylaminated paper coated with polyethylene resin on the surface of wood pulp paper can also be used. From the viewpoint of rigidity and strength, so-called cup base paper (also referred to as “cup base paper”) is particularly preferably used.

The basis weight of the paper substrate (D) is preferably from 30~600g / ^{m 2,} more preferably 100 to 500 g / ^{m 2,} more preferably in the range of 150 and 400 / ^{m 2.} If the basis weight of the paper substrate is too small, the heat resistance and strength of the multilayer sheet for insulated paper containers and the insulated paper container formed therefrom may be insufficient, and if the basis weight is too large, The processability of the container multilayer sheet may be deteriorated. The thickness of the paper substrate (D) is usually in the range of 50 μm to 2 mm, preferably 100 μm to 1.5 mm, more preferably 150 to 800 μm, and still more preferably 200 to 600 μm.

  The moisture content of the paper substrate (D) provided in the multilayer sheet for insulated paper containers of the present invention is preferably 2 to 15% by mass, more preferably 4 to 13% by mass, and still more preferably 5 to 10% by mass. Within range. If the moisture content of the paper substrate (D) is too low, foaming of the foamable low melting point thermoplastic resin layer (C) is insufficient due to evaporation of water contained in the paper substrate (D). Or uneven foaming may occur. If the water content of the paper substrate (D) is too high, the strength of the resulting multilayer sheet for insulated paper containers will be reduced, resulting in a decrease in molding processability, as well as excessive foaming and bursting of foamed cells. May be easier. The moisture content of the paper substrate (D) can be maintained at a desired level by controlling the environmental conditions including temperature and humidity to adjust the moisture content. The moisture content of the paper substrate (D) can be measured by an absolute dry moisture measurement method.

2. Thermoplastic resin layer (E)
The thermoplastic resin layer (E) with which the multilayer sheet for insulated paper containers of the present invention is provided is not particularly limited and can be formed from a thermoplastic resin that is usually used for insulated paper containers. For example, polyolefins such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene, polymethylpentene, etc. Can be mentioned. Examples of thermoplastic resins other than polyolefins include polyamide, polyacetal, polyphenylene sulfide, polystyrene, polyvinyl chloride, acrylic resin, and polycarbonate. Among these thermoplastic resins, polyolefin is preferable.

  The thermoplastic resin forming the thermoplastic resin layer (E) forms a foamable low-melting point thermoplastic resin layer (C), which will be described later, and a low-melting point thermoplastic resin layer (A). It is a thermoplastic resin having a melting point that is preferably 5 ° C. or higher, more preferably 8 ° C. or higher, and even more preferably 10 ° C. or higher compared to the melting point of the thermoplastic resin. [Therefore, the thermoplastic resin layer (E) may be referred to as a “high-melting point thermoplastic resin layer (E)” and the thermoplastic resin forming the thermoplastic resin layer (E) may be referred to as a “high-melting point thermoplastic resin”. The upper limit of the melting point difference is not particularly limited, but is usually 50 ° C., and in many cases 40 ° C. If the difference between the melting points is too small, in the step of foaming the foamable low melting point thermoplastic resin layer (C) by evaporation of water contained in the paper substrate (D), the thermoplastic resin layer (E The low melting point thermoplastic resin that melts the high melting point thermoplastic resin and diffuses water vapor through the thermoplastic resin layer (E), or a part of the high melting point thermoplastic resin is foamed or foamable. The foaming of the layer (C) may be insufficient.

Therefore, as the thermoplastic resin for forming the thermoplastic resin layer (E), medium density polyethylene (MDPE) and high density polyethylene (HDPE) or a mixture thereof is preferable. MDPE is more preferable from the viewpoint of stability and the like. The density of MDPE used as the thermoplastic resin for forming the thermoplastic resin layer (E) of the present invention is usually in the range of 930 to 941 kg / m ³ , and the density of HDPE is usually 942 to 970 kg / m ³ . Is in range. MDPE or HDPE may be obtained by copolymerizing a small amount of α-olefin as a comonomer. Typical examples of the α-olefin include 1-butene, 1-hexene, 1-octene and the like. The melting point of MDPE or HDPE is usually in the range of 120 to 135 ° C, preferably 122 to 135 ° C, more preferably 123 to 135 ° C. The density of MDPE and HDPE is a value measured according to JIS K 6748-1981. The melting point is a temperature detected as the maximum endothermic peak temperature (Tm) when measured using a differential scanning calorimeter (DSC) according to a conventional method unless otherwise specified. The MDPE or HDPE melt flow rate (MFR; measured by ASTM D1238) is preferably in the range of 3-15 g / 10 min, more preferably in the range of 5-12 g / 10 min.

  The thermoplastic resin forming the thermoplastic resin layer (E) may be a pigment (titanium oxide, calcium carbonate, clay, talc, silica, etc.), an antistatic agent, an anti-blocking agent (acrylic beads, glass beads, silica, etc.) as desired. ), Commonly used additives such as ultraviolet absorbers.

  The thickness of the thermoplastic resin layer (E) is determined in the step of foaming the foamable low melting point thermoplastic resin layer (C) by evaporation of the water contained in the paper substrate (D). When the thickness is such that it can be prevented from escaping and is disposed on the inner wall surface side of the heat insulating paper container formed from the resulting multilayer sheet for heat insulating paper containers (inner surface layer), heating with hot water or the like The thickness is not particularly limited as long as it can prevent the penetration of the liquid. The thickness of the thermoplastic resin layer (E) is preferably in the range of 15 to 60 μm, more preferably 20 to 50 μm.

3. Foamable low melting point thermoplastic resin layer (C)
The foamable low-melting point thermoplastic resin layer (C) provided in the multilayer sheet for heat-insulated paper containers of the present invention is foamed by evaporation of water contained in the paper base material (D), and is made of heat-insulated paper. It becomes the heat insulation layer of the heat insulating paper container formed from the multilayer sheet for containers. The thermoplastic resin forming the foamable low melting point thermoplastic resin layer (C) is not particularly limited as long as it can be foamed by evaporation of water contained in the paper substrate (D). The thermoplastic resin usually used to form the heat insulation layer of the insulated paper container can be used, but it is foamed by evaporation of the water contained in the paper substrate (D). From the viewpoint of ease, polyolefin is preferred. Examples of polyolefins include, for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene, and polymethylpentene. And the like, and these can be used alone or in combination. Particularly preferably, LDPE or LLDPE can be used alone or in combination. If desired, other thermoplastic resins other than polyolefin can be mixed and used. By changing the composition of the thermoplastic resin forming the foamable low-melting point thermoplastic resin layer (C), the foaming of the foamable low-melting point thermoplastic resin layer (C) can be controlled, and as a result It may be possible to adjust the smoothness of the surface of the insulated paper container formed on the surface.

The thermoplastic resin forming the foamable low-melting point thermoplastic resin layer (C) is preferably a thermoplastic resin having a melting point in the range of 80 to 120 ° C, more preferably 81 to 117 ° C, from the viewpoint of foamability. More preferably, it is the range of 82-115 degreeC. Among the low-melting thermoplastic resins, polyolefin is preferable as described above in view of excellent foamability, and LDPE, LLDPE, or a mixture thereof is particularly preferable. The density of LDPE or LLDPE particularly preferably used in the present invention is usually in the range of 910 to 929 kg / m ³ , preferably 911 to 925 kg / m ³ . The melting point of LDPE or LLDPE is preferably in the range of 98 to 120 ° C, more preferably 100 to 118 ° C, and still more preferably 102 to 115 ° C. The melting point is a value measured as a maximum endothermic peak temperature by a differential scanning calorimeter (DSC). The melt flow rate of LDPE or LLDPE (measured by ASTM D1238) is preferably in the range of 5-20 g / 10 minutes, more preferably in the range of 8-17 g / 10 minutes.

  The low-melting-point thermoplastic resin layer (C) that can be foamed is formed of a thermoplastic resin having a lower melting point than the thermoplastic resin that forms the thermoplastic resin layer (E). For the purpose, it is referred to as a foamable low melting point thermoplastic resin layer (C). That is, as described above, the melting point of the thermoplastic resin forming the foamable low melting point thermoplastic resin layer (C) is the same as that of the thermoplastic resin (high melting point thermoplastic resin) forming the thermoplastic resin layer (E). The thermoplastic resin has a melting point that is preferably 5 ° C. or lower, more preferably 8 ° C. or lower, and even more preferably 10 ° C. or lower. As described above, the upper limit of the difference in melting point is not particularly limited, but is usually 50 ° C., and in many cases 40 ° C.

  The thickness of the foamable low melting point thermoplastic resin layer (C) is usually within a range of 10 to 100 μm, preferably 20 to 80 μm. Further, the foamed thickness of the low-melting-point thermoplastic resin layer (C) after foaming is usually 100 to 2,000 μm, preferably 400 to 1,800 μm, more preferably 600 from the viewpoints of heat insulation and heat retention. Within the range of ˜1,500 μm.

  The thermoplastic resin that forms the foamable low-melting point thermoplastic resin layer (C) may be a pigment (titanium oxide, calcium carbonate, clay, talc, silica, etc.), an antistatic agent, an anti-blocking agent (acrylic beads, Glass beads, silica, etc.) and commonly used additives such as ultraviolet absorbers can be contained.

4). Print layer (B)
The printed layer (B) with which the multilayer sheet for heat-insulating paper containers of the present invention is used is used to give the heat-insulating paper container finally obtained a beautiful appearance image and distinctiveness as a product. Conventionally, in a heat insulating paper container, the printed layer corresponds to a paper base material and a heat insulating layer [the foamable low melting point thermoplastic resin layer (C) in the present invention. However, in this case, the heat insulating layer is made of a foamed thermoplastic resin layer, so that the transparency is low and the printed layer may not be clearly visible. In the present invention, since the printed layer (B) is formed on the upper surface of the foamable low-melting-point thermoplastic resin layer (C), the heat insulating paper container finally obtained is printed from the outer surface to the printed layer ( B) can be clearly recognized, and is effective for improving the appearance image and the distinguishability.

  The printing layer (B) is not particularly limited, and may be one in which characters, patterns, pictures or the like are formed, or a simple colored layer or a so-called concealing layer. For example, when the multilayer sheet for a heat-insulating paper container of the present invention is for forming the bottom member of the heat-insulating paper container, the printed layer (B) can often be formed as a concealing layer. The printing layer (B) has a pattern printing layer (B1) adjacent to the low-melting point thermoplastic resin layer (A), which will be described in detail later, and solid printing on the opposite side of the low-melting point thermoplastic resin layer (A). The layer (B2) is preferred, so that the letters, patterns, pictures, etc. formed on the pattern printing layer (B1) can be seen more clearly, so that the multilayer sheet for insulated paper containers of the present invention However, when it is for forming the trunk | drum member of a heat-insulating paper container, it becomes a desirable aspect.

[Solid printing layer (B2)]
The solid printing layer (B2) adjacent to the foamable low-melting point thermoplastic resin layer (C) is a printing layer covering almost the entire surface of the foamable low-melting point thermoplastic resin layer (C). Alternatively, it can be formed by solid printing of transparent ink, and may be monochromatic printing or multicolor printing. When the solid printing layer (B2) is used as a concealing layer, white ink or colored ink is usually used, so that characters, patterns, pictures, etc. formed on the pattern printing layer (B1) can be seen more clearly. Therefore, a solid print layer (B2) formed using white ink is often preferable. As the ink for forming the solid print layer (B2), a foamable ink is used, and a foamed solid print layer (B2) may be used. In that case, a solid print obtained by foaming a part of the solid print layer (B2) It is good also as a layer (B2). In addition, in the conventional multilayer sheet for heat-insulating paper containers, in order to use the foamable low-melting-point thermoplastic resin layer (C) as a heat seal layer, the formation of the solid printing layer (B2) is performed by heat sealing. It was necessary to do so to remove the part. However, in the present invention, it is not necessary to use the foamable low-melting-point thermoplastic resin layer (C) as a heat seal layer, and therefore it is easy to form a solid print layer (B2).

[Pattern printing layer (B1)]
In the printing layer (B), the pattern printing layer (B1) on the opposite side of the foamable low melting point thermoplastic resin layer (C) is on the upper surface of the solid printing layer (B2), and the characters, patterns, pictures A broad pattern that can be seen from the outer surface of the insulated paper container is formed. For example, it is possible to display a product name, a pattern, a description, a symbol, and a design and a design, and may be monochromatic printing or multicolor printing. Characters, patterns, pictures and the like formed on the pattern print layer (B1) can be formed using an appropriate ink. As the ink used for forming the pattern printing layer (B1), a foaming ink containing a foaming agent or a foaming inhibitory ink containing a foaming inhibitor may be used. When a pattern is formed on the material (D) or the like, a pattern printing layer (B1) may be provided so as to be synchronized with the pattern. As described above, in the conventional multilayer sheet for heat-insulated paper containers, the pattern printed layer (B1) needs to be formed so as to exclude the heat seal portion. Thus, the pattern printing layer (B1) can be easily applied to the vicinity of the heat seal portion.

  The ink used for forming the printing layer (B), preferably the solid printing layer (B2) and the pattern printing layer (B1) is not particularly limited, and water-based ink, oil-based ink, sublimation ink, etc. should be used. Can do. Conventionally, in a multilayer sheet for a heat insulating paper container for forming a heat insulating paper container for food, it is preferable to use a water-based ink or a sublimation ink because of concern about the persistence of the organic solvent in the ink. It was sometimes said. As will be described later, the multilayer sheet for heat-insulating paper containers of the present invention includes the low-melting point thermoplastic resin layer (A) on the upper surface of the printing layer (B), and therefore, oil-based ink can often be used. In addition, when the solid printing layer (B2) is a concealing layer, it goes without saying that a white pigment such as titanium oxide or other pigments may be contained.

  The formation method of the printing layer (B) is not particularly limited, and gravure printing, roll printing, spray printing, screen printing, flexographic printing, and other ordinary printing methods can be employed, but the printing finish, workability, and processing A printing layer (B) formed by gravure printing is preferable in terms of speed and the like. When the printing layer (B) includes the solid printing layer (B2) and the pattern printing layer (B1), the solid printing layer (B2) and the pattern printing layer (B1) may be formed by different methods. .

  The thickness of the printing layer (B) is not particularly limited, and is usually 0.01 to 200 μm, preferably 0.05 to 150 μm, more preferably 0.1 to 100 μm. When the printing layer (B) is composed of the solid printing layer (B2) and the pattern printing layer (B1), the ratio of the thickness of the solid printing layer (B2) and the pattern printing layer (B1) is not particularly limited. The range is usually 1:10 to 10: 1, preferably 2: 8 to 8: 2.

5). Low melting point thermoplastic resin layer (A)
The multilayer sheet for insulated paper containers of the present invention is characterized in that the low-melting point thermoplastic resin layer (A) is formed on the upper surface of the print layer (B). The low-melting point thermoplastic resin layer (A) provided in the multilayer sheet for heat-insulating paper containers of the present invention is formed on the upper surface of the printing layer (B) to protect the printing layer (B) and heat-insulating paper. It has the function of smoothing the surfaces of the multilayer sheet for container-making and the finally formed heat-insulating paper container, and can usually also have the function of a heat seal layer. Furthermore, since the low-melting-point thermoplastic resin layer (A) is usually the outermost surface layer (outer surface layer) of a heat-insulating paper container provided with a member formed from a multilayer sheet for heat-insulating paper containers, It is required to have solvent resistance as well as not to contain harmful components from the viewpoint of hygiene, because it is used for ingesting the contents and by hand to carry it. There are many cases.

  The low-melting point thermoplastic resin layer (A) is formed from a thermoplastic resin having a lower melting point than the thermoplastic resin forming the thermoplastic resin layer (E). This is referred to as a low melting point thermoplastic resin layer (A). As described above, the melting point of the thermoplastic resin forming the low melting point thermoplastic resin layer (A) is preferably higher than that of the thermoplastic resin (high melting point thermoplastic resin) forming the thermoplastic resin layer (E). It is a thermoplastic resin having a melting point of 5 ° C. or lower, more preferably 8 ° C. or lower, and even more preferably 10 ° C. or lower. As described above, the upper limit of the difference in melting point is not particularly limited, but is usually 50 ° C., and in many cases 40 ° C.

  The difference in melting point between the thermoplastic resin forming the low-melting thermoplastic resin layer (A) and the thermoplastic resin forming the foamable low-melting thermoplastic resin layer (C) is less than 5 ° C. More preferably, it is 4 ° C. or less, more preferably 3.5 ° C. or less, particularly preferably 3 ° C. or less, and most preferably there is substantially no difference in melting point. If the difference in melting point between the thermoplastic resin forming the low-melting thermoplastic resin layer (A) and the thermoplastic resin forming the foamable low-melting thermoplastic resin layer (C) is 5 ° C. or more, it is made of heat insulating paper In the step of foaming the foamable low-melting point thermoplastic resin layer (C) by evaporating the water contained in the paper base material (D) by heating the multilayer sheet for containers, the low-melting point thermoplastic resin Since the layer (A) is difficult to soften and has a large viscosity, foaming of the foamable low-melting point thermoplastic resin layer (C) is suppressed, and a problem that the desired foamed layer thickness cannot be obtained may occur.

  Accordingly, the low-melting point thermoplastic resin layer (A) is not particularly limited as long as it has the above-described function, and a thermoplastic resin usually used in a heat-insulated paper container can be used. The thermoplastic resin forming the thermoplastic resin layer (A) and the thermoplastic resin forming the foamable low melting point thermoplastic resin layer (C) may be different thermoplastic resins, for example, belonging to the same type Different thermoplastic resins or different brands may be used.

  As the thermoplastic resin for forming the low melting point thermoplastic resin layer (A), polyolefin is preferable from the viewpoint of smoothing the surface of the heat insulating paper container or making it a heat seal layer. Examples of the polyolefin include polyolefins such as LDPE, LLDPE, VLDPE, MDPE, HDPE, polypropylene, polymethylpentene, and the like. These can be used alone or in combination. Particularly preferably, LDPE or LLDPE can be used alone or in combination. If desired, other thermoplastic resins other than polyolefin can be mixed and used. By changing the composition of the thermoplastic resin that forms the low-melting-point thermoplastic resin layer (A), the smoothness of the surface of the heat-insulating paper container that is finally formed may be adjusted. As described above, the polyolefin forming the low-melting point thermoplastic resin layer (A) and the polyolefin forming the foamable low-melting point thermoplastic resin layer (C) may be polyolefins corresponding to different brands. .

The melting point of the thermoplastic resin forming the low-melting-point thermoplastic resin layer (A) is preferably in the range of 80 to 120 ° C, more preferably 81 to 117 ° C, still more preferably 82 to 115 ° C. . As stated above, polyolefins are particularly preferred, with LDPE or a mixture of LDPE and LLDPE being most preferred. The density of LDPE or LLDPE used in the present invention is usually in the range of 910 to 929 kg / m ³ , preferably 911 to 925 kg / m ³ . The melting point of LDPE or LLDPE is preferably in the range of 98 to 120 ° C, more preferably 100 to 118 ° C, and still more preferably 102 to 115 ° C. The melt flow rate of LDPE or LLDPE (measured by ASTM D1238) is preferably in the range of 5-20 g / 10 minutes, more preferably in the range of 8-17 g / 10 minutes.

  The thermoplastic resin forming the low-melting-point thermoplastic resin layer (A) optionally contains commonly used additives such as pigments or fillers, matting agents, antistatic agents, antiblocking agents, and UV absorbers. can do. The content thereof may be selected in an optimum range depending on the type of additive, and is 0.001 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin forming the low melting point thermoplastic resin layer (A). In many cases, it is in the range of 0.01 to 20 parts by mass.

[Delustering agent]
If particularly desired, the low-melting point thermoplastic resin layer (A) is formed from a thermoplastic resin containing a matting agent, thereby forming a multilayer sheet for insulated paper containers and finally formed. The surface of the insulated paper container having a glossy (matt) appearance can be used instead of being glossy, and in this case, the sensation of the container surface can be prevented. As matting agents, commonly used matting agents such as silica, titanium oxide, calcium carbonate, clay, talc and other inorganic powders, as well as resin powders such as ultra-high molecular weight polyethylene powders can be used. Silica is preferred. The content thereof is in the range of 0.001 to 10 parts by mass with respect to 100 parts by mass of the thermoplastic resin forming the low melting point thermoplastic resin layer (A), and in many cases 0.01 to 5 parts by mass. It is a range.

  The thickness of the low-melting-point thermoplastic resin layer (A) is usually in the range of 1 to 50 μm, preferably 3 to 40 μm, more preferably 5 to 30 μm.

6). Barrier layer (F)
The multilayer sheet for insulated paper containers according to the present invention is a container having a member formed from the multilayer sheet for containers. In order to impart a flavor barrier property that does not dissipate into the film, a barrier layer (F) may be further provided.

  As the barrier layer (F), a metal thin film such as an aluminum foil, an inorganic oxide thin film such as aluminum oxide or silicon dioxide, a barrier resin film, a metal or inorganic oxide vapor-deposited film, or a composite thereof is used. However, from the viewpoint of microwave heating characteristics, the use of a metal vapor deposited film or a metal thin film may not be desirable. The barrier layer (F) provided in the multilayer sheet for insulated paper containers of the present invention is preferably a barrier resin film or an inorganic oxide vapor deposition film. Examples of the barrier resin film include polyamide (MXD nylon, etc.), vinylidene chloride (co) polymer, ethylene-vinyl alcohol copolymer (so-called EVOH), PET (polyethylene terephthalate), and acrylic acid-based barrier resin. Etc. Examples of the inorganic oxide vapor-deposited film include an aluminum oxide vapor-deposited PET film and a silicon dioxide vapor-deposited PET film. Examples of the composite include an acrylic acid-based barrier resin-coated PET film. In consideration of the balance of gas barrier properties, flavor barrier properties, and processability, a PET film, an aluminum oxide-deposited PET film, or an acrylic acid-based barrier resin-coated PET film is preferable. As the barrier resin film or the inorganic oxide vapor-deposited film, an extruded film may be used, or a film formed by coating may be used.

  In the multilayer sheet for insulated paper containers, the position of the barrier layer (F) is not particularly limited, but the low melting point that can be foamed by the moisture evaporated by heating and evaporating the moisture contained in the paper substrate (D) From the viewpoint of not preventing foaming of the thermoplastic resin layer (C), it is preferable to provide a barrier layer (F) between the paper substrate (D) and the thermoplastic resin layer (E). When the multilayer sheet for insulated paper containers is provided with a barrier layer (F) between the paper substrate (D) and the thermoplastic resin layer (E), the barrier layer (F) It may be one laminated with one or both of the substrate (D) and the thermoplastic resin layer (E).

  Although the thickness of a barrier layer (F) is not specifically limited, Usually, 0.01-50 micrometers, Preferably it is 0.05-40 micrometers, More preferably, it is the range of 0.1-30 micrometers.

  The multilayer sheet for a heat-insulating paper container provided with the barrier layer (F) can be formed on any of the body member and the bottom member of the heat-insulating paper container, and in particular, made of heat-insulating paper provided with the barrier layer (F). It is preferable to use a heat insulating paper container provided with a body member formed from a multilayer sheet for containers. Moreover, since the barrier property further improves, the heat insulating paper container further provided with the bottom member formed from the multilayer sheet for heat insulating paper containers provided with a barrier layer (F) is more preferable.

7). Adhesive Layer The multilayer sheet for insulated paper containers of the present invention may be provided with an adhesive layer formed from an adhesive between the respective layers, if necessary, but formed from the multilayer sheet for containers. The use of an adhesive may be unfavorable because the organic solvent may be volatilized when cooking the food filled in the container having the prepared member. As an adhesive that can be used, an adhesive resin having a functional group such as a carboxyl group, an acid anhydride group, a hydroxyl group, a carbonyl group, a glycidyl group (epoxy group), an isocyanate group, an amino group, an imide group, or a urethane group is preferable. . Examples include adhesive resins such as carboxylic anhydride-modified polyolefins such as maleic anhydride-modified polyethylene, glycidyl group-containing ethylene copolymers, thermoplastic polyurethanes, polyamide ionomers, polyacrylimides, and acid-modified linear low density polyethylene. These adhesive resins can be used alone or blended with LDPE, MDPE or HDPE.

  The thickness of each adhesive layer is not particularly limited as long as it can perform the function of adhesion and does not impair the effect of the multilayer sheet for a heat insulating paper container, but is usually 0.01 to 20 μm, preferably The range is 0.02 to 18 μm, more preferably 0.05 to 16 μm. The adhesive layer can be formed by coating or coextrusion.

8). Other layers The multilayer sheet for insulated paper containers of the present invention may further include other layers as necessary. For example, an ink receiving layer containing a pigment and a binder can be provided on the surface on which the printing layer (B) is formed, that is, on the upper surface of the foamable low melting point thermoplastic resin layer (C). The thickness of these other layers is not particularly limited as long as the effect of the multilayer sheet for a heat insulating paper container is not impaired, but is usually 0.01 to 200 μm, preferably 0.02 to 150 μm, more preferably 0.00. It is in the range of 03 to 100 μm and in many cases 0.05 to 50 μm.

9. Multilayer sheet for insulated paper container The multilayer sheet for insulated paper container of the present invention is, for example, a low-melting point thermoplastic resin layer (A), a printed layer (B), and a foamable low melting point as shown in FIG. A multilayer sheet for a heat insulating paper container comprising a thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) in this order. It is a multilayer sheet for insulated paper containers provided with a barrier layer (F) between a material (D) and a thermoplastic resin layer (E). As described above, the resin that forms the low melting point thermoplastic resin layer (A), the foamable low melting point thermoplastic resin layer (C), and the thermoplastic resin layer (E) is preferably a polyolefin.

  The size of the multilayer sheet for insulating paper containers of the present invention is not particularly limited as long as it can be manufactured and is suitable for forming an insulating paper container. Further, it may be a long body, or may be a polygon such as a square having a predetermined size, a circle (complete circle or part), an ellipse, a fan shape, or other shapes. The total thickness of the multilayer sheet for heat-insulating paper containers of the present invention can be appropriately selected from the range of usually 50 μm to 2 mm, preferably 100 μm to 1.5 mm, more preferably 150 μm to 1 mm, and still more preferably 200 to 700 μm. . The thickness of the multilayer sheet for insulated paper containers is measured using a cross-sectional photograph (the same applies to the thickness of each layer of the multilayer sheet for insulated paper containers).

[Low temperature heat sealability]
The multilayer sheet for insulated paper containers of the present invention having a low-melting point thermoplastic resin layer (A) is excellent in low-temperature heat-sealability and has no low-melting point thermoplastic resin layer (A). Heat sealing can be performed at a lower temperature than the sheet. That is, the multilayer sheet for insulated paper containers according to the present invention is subjected to heat sealing under the same heating time (for example, selected from 1 to 3 seconds) and the same heat sealing pressure condition (for example, 1 kN) to be predetermined. When trying to obtain a sealing strength of 5 ° C., the temperature is usually 15 ° C. or more, preferably 20 ° C. or more, more preferably 22 ° C. or more lower than the multilayer sheet for heat-insulating paper containers not provided with the low melting point thermoplastic resin layer (A). Can be heat sealed. Since the multilayer sheet for heat-insulating paper containers of the present invention is excellent in low-temperature heat-sealability, the time required for heat sealing to form the heat-insulating paper container can be shortened. Productivity is improved.

The heat-sealability of the heat-insulating paper container multilayer sheet is measured and evaluated by the following methods 1) to 3) using the heat-insulating paper multilayer sheet prepared by heating and foaming the heat-insulating paper container multilayer sheet as a sample. be able to. That is,
<Preparation of sample>
A multilayer sheet for a heat insulating paper container cut into a square having a width of 150 mm and a length of 150 mm, using a blown constant temperature dryer windy oven WFO-601SD type (turntable installation type) manufactured by Tokyo Rika Machinery Co., Ltd. A heat sealing property evaluation sample is prepared by placing the multilayer sheet on the turntable with the foamable low melting point thermoplastic synthetic resin layer (C) as the upper surface and heating and foaming at a temperature of 130 ° C. for 5 minutes.
<Measurement of heat sealability>
1) A thermoplastic resin layer (E) and a low-melting point thermoplastic resin layer (A) of a multilayer sheet made of heat-insulating paper as a sample, using a heat sealer and using a seal bar having a width of 10 mm and a length of 50 mm, After heat sealing at a set temperature and a seal pressure of 1 kN for 2 seconds, using a tensile tester, a tensile test is performed under the conditions described below (hereinafter sometimes referred to as “material failure conditions”), and material failure occurs. Temperature (hereinafter, also referred to as “material destruction temperature”).
2) As a control, using a heat-insulated paper multilayer sheet prepared from a heat-insulated paper container multilayer sheet (hereinafter sometimes referred to as “control sheet”) without the low-melting point thermoplastic resin layer (A), After performing heat sealing under the same conditions as in 1), a tensile test is performed under the above-described material breaking conditions, and the material breaking temperature of the control sheet is measured. At that time, the control sheet not provided with the low melting point thermoplastic resin layer (A) does not form the printing layer (B) at the place where heat sealing is performed according to a conventional method. The layer (C) (already foamed) is exposed, and the exposed foamable low-melting-point thermoplastic resin layer (C) and the thermoplastic resin layer (E) are heat-sealed.
3) Based on the difference between the material destruction temperature of the insulating paper multilayer sheet as a sample and the material destruction temperature of the insulating paper multilayer sheet prepared from the control sheet (hereinafter, sometimes referred to as “heat seal temperature difference”). The low temperature heat sealability is evaluated according to the following criteria.
The multilayer sheet for insulated paper containers of the present invention has an evaluation of A, and the heat sealing temperature difference is preferably 20 ° C. or higher, more preferably 22 ° C. or higher.
<Material destruction conditions>
Sample size: 15 mm wide and 50 mm long (cut into a rectangle along the heat seal part)
Distance between chucks: 25mm
Tensile speed: 200 mm / min Peeling form: 180 degree peeling <Evaluation criteria for low temperature heat sealability>
A: The heat seal temperature difference is 15 ° C. or higher (heat seal can be performed at a lower temperature).
B: The heat seal temperature difference is 5 ° C. or more and less than 15 ° C. (can be heat sealed at a slightly low temperature).
C: The heat seal temperature difference is less than 5 ° C. or the material destruction temperature is higher than that of the control sheet.

  The reason why the multilayer sheet for insulated paper containers of the present invention is excellent in low-temperature heat sealability is not necessarily clear, but in the multilayer sheet for insulated paper containers (control sheet) that does not include the low-melting point thermoplastic resin layer (A). When the heating (usually a temperature of 100 to 120 ° C.) is carried out to dry the printing layer (B) formed on the foamable low-melting point thermoplastic resin layer (C), the printing layer (B ) To form a heat seal layer due to the influence of the surface treatment (corona discharge treatment, anchor coating application, etc.) applied to the low-melting-point thermoplastic resin layer (C) that can be foamed prior to the formation of Since the possible low melting point thermoplastic resin layer (C) is oxidized and the heat seal strength with the thermoplastic resin layer (E) decreases, the required heat seal strength can be obtained unless heat sealing is performed at a higher temperature. Not even It is presumed that. On the other hand, in the multilayer sheet for insulated paper containers according to the present invention, the low-melting point thermoplastic resin layer (A) is not affected by the surface treatment, so it is necessary even if heat sealing is performed at a lower temperature. It is inferred that the heat seal strength can be obtained.

  In addition, the multilayer sheet for a heat-insulating paper container of the present invention includes a low-melting point thermoplastic resin layer (A), a printing layer (B), a thermoplastic resin layer (E), a paper base material (D), and A multilayer sheet for heat-insulating paper containers, comprising the foamable low melting point thermoplastic resin layer (C) in this order, may be used. If desired, a barrier layer (F) can be further provided between the paper substrate (D) and the thermoplastic resin layer (E). This multilayer sheet for insulated paper containers is provided with a low-melting point thermoplastic resin layer (A) on the upper surface of the printing layer (B), so that the printing surface is protected, the printing is clear and the surface is beautiful, In addition, as described above, the same effect as that of the multilayer sheet for a heat-insulating paper container can be achieved, and the printed layer (B) is usually smooth. It may be evaluated that the cosmetics of the printed layer (B) are more excellent by being formed on the upper surface of the thermoplastic resin layer (E), and the foamable low melting point thermoplasticity Since there is no need to form the printing layer (B) on the upper surface of the resin layer (C), the foamable low melting point thermoplastic resin layer (C) can be designed to have a higher expansion ratio. May be. As described above, the resin that forms the low melting point thermoplastic resin layer (A), the foamable low melting point thermoplastic resin layer (C), and the thermoplastic resin layer (E) is preferably a polyolefin.

10. Method for producing multilayer sheet for insulated paper container The method for producing a multilayer sheet for insulated paper container according to the present invention comprises a low-melting point thermoplastic resin layer (A), a printed layer (B), and a foamable low-melting point thermoplastic resin. There is no particular limitation as long as a multilayer sheet for a heat insulating paper container provided with a layer (C), a paper base (D), and a thermoplastic resin layer (E) can be obtained. The multilayer sheet for heat-insulating paper containers of the present invention is a lamination method used when producing an ordinary multilayer sheet for containers, for example, a wet lamination method in which lamination is performed using an adhesive, a sandwich lamination method, a dry lamination method. Further, it can be produced by a thermal lamination method, a solventless lamination method, an extrusion lamination method in which lamination is performed by melt coating of a resin, a coextrusion lamination method, an inflation method, a coextrusion inflation method, or the like. Since the production efficiency is good, in particular, the step of drying the adhesive is not required, a production method using a resin melt coating is preferably employed.

  For example, the surface of the printing layer (B) of a multilayer sheet comprising a printing layer (B), a foamable low-melting point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) In addition, a method for producing a multilayer sheet for a heat insulating paper container, which includes a step of forming a low melting point thermoplastic resin layer (A) by melt coating a low melting point thermoplastic resin, is preferably employed. More preferably, the foamable low-melting point thermoplastic resin layer (C), the paper substrate (D), and the thermoplastic resin layer (E) are laminated in this order. That is, a multilayer sheet formed from a printed layer (B) and a multilayer sheet comprising a foamable low-melting point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) in this order. More preferable is a method for producing a multilayer sheet for insulated paper containers, which includes a step of melt-coating a low-melting point thermoplastic resin on the surface of the printed layer (B) of the sheet to form a low-melting point thermoplastic resin layer (A). .

  Furthermore, in order to obtain a multilayer sheet comprising the print layer (B), a foamable low melting point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E), foaming is performed. Insulating paper including a step of forming a printing layer (B) on the surface of a multilayer sheet comprising a low-melting-point thermoplastic resin layer (C), a paper base (D), and a thermoplastic resin layer (E) in this order. The manufacturing method of the multilayer sheet for container-making is more preferably adopted. As described above, since it is not necessary to form the printing layer (B), particularly the solid printing layer (B2) so as to remove the heat seal portion, the printing layer (B), particularly the solid printing layer. The formation of (B2) is easy, and the effect of being excellent in efficiency and economy is achieved.

  Furthermore, in order to obtain a multilayer sheet comprising the foamable low-melting-point thermoplastic resin layer (C), the paper base material (D) and the thermoplastic resin layer (E) in this order, a paper base material (D ) And a thermoplastic resin layer (E), a foamable low-melting point thermoplastic resin layer (C) is formed on the surface opposite to the thermoplastic resin layer (E) of the paper substrate (D) of the multilayer sheet. The manufacturing method of the multilayer sheet for insulated paper containers including the step of forming is particularly preferably employed.

  When the multilayer sheet for insulated paper containers of the present invention is provided with a barrier layer (F), the barrier layer (F) is either one of the paper substrate (D) or the thermoplastic resin layer (E) or By including a step of laminating both by adhesion, a multilayer sheet for insulated paper containers comprising a barrier layer (F) between a paper substrate (D) and a thermoplastic resin layer (E) It is preferable that it is a manufacturing method.

  In addition, when performing lamination, in order to improve the adhesion between the laminated layers, one or both surfaces of the laminated layers are subjected to conventional surfaces such as corona treatment, ozone treatment or flame treatment. It is preferable to perform a surface treatment by treatment or application of an anchor coating agent such as polyethyleneimine, polybutadiene, or organic titanium. In particular, it is often preferable to perform the surface treatment on the surface of the paper substrate (D).

  The size of the multilayer sheet for heat-insulating paper containers of the present invention is not particularly limited as described above, but is usually 10 to 200 cm in width, and preferably from 30 to 30 in terms of ease of manufacture and handling convenience. It can be manufactured as an elongated body having a width of 180 cm, more preferably 50 to 150 cm, and can be manufactured by cutting or punching into a predetermined shape as desired.

11. Insulated paper container and method for producing insulated paper container The insulated paper container of the present invention is an insulated paper container comprising a member formed from the multilayer sheet for insulated paper containers, and more specifically, In particular, the insulated paper container as shown in FIG. 1 is provided with a trunk member or a bottom member formed from the multilayer sheet for insulated paper containers.

  The heat insulating paper container of the present invention is a heat insulating paper container provided with a member such as a trunk member or a bottom member formed from the multilayer sheet for a heat insulating paper container. There is provided a heat insulating paper container comprising a foamable low-melting point thermoplastic resin layer and a printed layer, wherein the heat insulating paper container has a clear print, a beautiful surface, and excellent scratch resistance and hygiene.

  As a heat insulating paper container including a body member and a bottom member, a heat insulating paper container including a substantially cylindrical or substantially truncated cone body member and a bottom member joined to the body member is known. Such a heat insulating paper container is widely known per se, and usually, the upper end of the body member is wound outward and the lower end of the body member is folded inward. On the other hand, the periphery of the bottom member is bent outward, and the folded portion at the lower end of the body member and the bent portion at the periphery of the bottom member are joined. Various printings can be applied to the body member and / or the bottom member. For example, in the case of a heat insulating paper container comprising a barrel member formed from the multilayer sheet for insulated paper containers of the present invention and a bottom member formed from the multilayer sheet for insulated paper containers of the present invention, Since both bottom members are provided with the printing layer (B), it is a heat insulating paper container in which printing is performed on both the body member and the bottom member.

  As a method for producing a heat insulating paper container having a body member and a bottom member, for example, a cup-shaped heat insulating paper container comprising a substantially cylindrical body member and a substantially circular bottom member, a container known per se The manufacturing method can be adopted. For example, the container manufacturing method is as follows. That is, a cut mark printed by using a punching machine (punching machine) and slitting a raw sheet of a multi-layer container sheet formed in advance (for example, about 1000 mm in width) in line with a printing position. A blank cut is made in a fan shape according to. Subsequently, using a container forming machine, both ends of the blank-cut sheet material are joined to form a barrel member, the lower end portion of the barrel member is bent into a predetermined shape, and a substantially circular shape separately formed The container can be obtained by bending the peripheral part of the bottom member into a predetermined shape and joining the joined part by hot pressing with a hot plate or the like. The same sheet material may be used for the sheet material forming the body member (the original sheet of the multilayer sheet for containers) and the sheet material forming the bottom member (the original sheet of the multilayer sheet for containers). Sheet materials having different configurations and / or compositions may be used.

  The insulated paper container of the present invention is preferably an insulated paper container provided with a trunk member or a bottom member formed from the multilayer sheet for insulated paper containers of the present invention. That is, the insulated paper container of the present invention includes 1) a body member formed from the multilayer sheet for insulated paper containers of the present invention and a bottom member formed from the multilayer sheet for insulated paper containers of the present invention. Insulated paper container 2) Insulated paper container comprising a barrel member formed from the multilayer sheet for insulated paper container of the present invention and other bottom member, or 3) Multilayer sheet for insulated paper container of the present invention Any of a heat insulating paper container provided with a bottom member formed from the above and other body members may be used. Particularly preferred is 1) a heat insulating paper container comprising a body member formed from the multilayer sheet for heat insulating paper containers of the present invention and a bottom member formed from the multilayer sheet for heat insulating paper containers of the present invention.

  For example, a low-melting-point thermoplastic resin layer (A), a printing layer (B), a foamable low-melting-point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer ( In order to manufacture a paper container using the multilayer sheet for paper containers, the heat-insulated paper container of the present invention including members formed from the multilayer sheet for heat-insulated paper containers of the present invention including E) in this order It can be obtained by the usual method employed as described above. That is, for example, the multilayer sheet for insulated paper containers of the present invention is subjected to drawing or bending after forming a predetermined cutout or notch as necessary, and an additional bonding step is added if necessary. Thus, a heat insulating paper container can be manufactured as the shape of the container.

  Preferably, the low-melting point thermoplastic resin layer (A), the printing layer (B), the foamable low-melting point thermoplastic resin layer (C), the paper substrate (D) and the thermoplastic resin layer (E) A member formed from the multilayer sheet for insulated paper containers, including the step of heat-sealing the end of the multilayer sheet for insulated paper containers according to the present invention, and in particular, made of insulated paper comprising a trunk member or a bottom member It is a manufacturing method of a container.

  For example, the low-melting point thermoplastic resin layer (A) of the multilayer sheet for a heat-insulating paper container of the present invention is used as a heat-sealing layer having heat-sealing properties, and the body member of the heat-insulating paper container has a developed shape (for example, a fan shape) The multi-layer sheet for a heat insulating paper container that has been cut is deformed (wrapped around a mandrel) so that the thermoplastic resin layer (E) becomes the inner surface of the body member of the heat insulating paper container (such as the shape of the side surface of the truncated cone). After that, the heat-seal layer composed of the low-melting point thermoplastic resin layer (A) at one end of the multi-layer sheet for heat-insulating paper containers is coated with the multi-layer sheet for heat-insulating paper containers. The body member of the insulated paper container can be obtained by melting the heat seal layer by superimposing it on the thermoplastic resin layer (E) at the other end of the layer and applying heat and pressure.

  Moreover, the multilayer sheet for insulated paper containers of the present invention cut into a substantially circular shape can be used as the bottom member of the insulated paper containers. At that time, the multilayer sheet for insulated paper containers of the present invention used as the trunk member and the multilayer sheet for insulated paper containers of the present invention used as the bottom member may have the same configuration, but a part of the configuration may be different. You may do it. Subsequently, the low melting point thermoplastic resin layer (A) of the multilayer sheet for insulated paper containers of the present invention, which is the bottom member, and the thermoplastic resin layer (E) positioned on the inner surface of the body member of the insulated paper container described above, By overlapping and heating and pressurizing, the body member and the bottom member can be joined by melting the heat seal layer to obtain a container-shaped assembly. If desired, the thermoplastic resin layer (E) of the multilayer sheet for a heat-insulating paper container of the present invention, which is the bottom member, may be a thermoplastic resin layer (E) located on the inner surface of the body member of the heat-insulating paper container. ) And heating and pressurizing to perform heat sealing, and joining the body member and the bottom member to obtain a container-shaped assembly. In order to make the insulated paper container have water tightness, it is preferable that the joint portion between the bottom member and the trunk member is wound according to a conventional method.

  Subsequently, the obtained container-shaped assembly is heated to a temperature at which moisture contained in the paper substrate (D) can be evaporated and expanded using a heating device such as an oven, a heater, or a hot air blower. Then, by foaming the foamable thermoplastic resin layer (C), the heat insulating paper container can be formed to produce the heat insulating paper container of the present invention. In addition, depending on necessity, instead of heating the foam-shaped thermoplastic resin layer (C) by heating the container-shaped assembly, a body member formed from a multilayer sheet for insulated paper containers and / or By heating the bottom members separately, the foamable thermoplastic resin layer (C) can also be foamed.

12 Performance Evaluation of Insulated Paper Container The insulated paper container of the present invention is a thermally insulated paper container having a clear print, a beautiful surface, and excellent scratch resistance and hygiene. Specifically, it is an insulated paper container having excellent gloss, excellent solvent resistance and scratch resistance, and excellent cosmetic properties, and can be evaluated by the properties measured by the following methods.

[Glossiness of insulated paper container]
The insulated paper container provided with the member formed from the multilayer sheet for insulated paper containers of the present invention has excellent gloss. The glossiness of the insulated paper container is determined by cutting a sample from the insulated paper container into a size of 10 cm wide × 10 cm long, placing it on a flat plate, and using a gloss meter to determine both the incident angle and the reflection angle. Measurement is performed in the length direction and the width direction at 60 °. In addition, a length direction means the length direction when manufacturing the multilayer sheet for insulated paper containers, and the width direction means a direction orthogonal to the length direction. As the measurement points of glossiness, measurement is performed on five white background portions where color printing is not performed, and the average value of n = 5 is defined as the glossiness of the insulated paper container (unit:%). As a sample, in order to avoid variations in measured values of glossiness, measurement was performed using an alternative to a heat insulating paper container, for example, the heat sealability evaluation sample (heat insulating paper multilayer sheet) described above. May be performed. The insulated paper container of the present invention has a glossiness of 10% or more in both the length direction and width direction, preferably 13% or more, more preferably 16% or more. The conventional insulated paper container had a glossiness of less than 10%.

[Solvent resistance of insulated paper containers]
The insulated paper container provided with the member formed from the multilayer sheet for insulated paper containers of this invention is excellent in chemical resistance. The chemical resistance of the insulated paper container can be evaluated for four types of solvents: methyl ethyl ketone, ethyl acetate, ethanol and toluene. Specifically, a sample is cut out in a size of 10 cm in width and 10 cm in length including a portion printed in red from a heat-insulated paper container, placed on a flat plate, and a portion printed in red One drop of each solvent is dripped onto the outer surface of each using a syringe, and after 10 seconds, the surface of the red printed portion is visually observed to evaluate the solvent resistance against each solvent. The evaluation criteria are as follows, and the insulation resistance of the insulated paper container of the present invention is A.
<Evaluation criteria>
Evaluation A: There is no bleeding of the solvent on the surface, the pattern and characters are not damaged by the solvent, and the surface gloss is not changed.
Evaluation B: There is a slight blur of the solvent on the surface, and the pattern and characters are slightly damaged by the solvent.
Evaluation C: Red printing ink is melted and pattern / character damage is observed.

[Scratch resistance of insulated paper containers]
The insulated paper container provided with the member formed from the multilayer sheet for insulated paper containers of the present invention is excellent in scratch resistance, and the surface is hardly damaged. The scratch resistance of the insulated paper container is cut out from the insulated paper container to a size of 10 cm wide × 20 cm long and placed on a flat plate. Ten evaluators are black on the outer surface of the insulated paper container. Based on the result of each evaluator evaluating the easiness of drawing a line when drawing a straight line with a length of about 10 cm with a ballpoint pen according to a predetermined standard, the evaluation result of a majority of evaluators is obtained from the scratch resistance of the insulated paper container. Sexually. Evaluation criteria are as follows, and the heat-resistant paper container of the present invention has an evaluation of scratch resistance of A.
<Evaluation criteria>
Evaluation A: The tip of the pen is slippery, the surface is not scratched at all, and the pattern and characters are not damaged.
Evaluation B: The nib is caught slightly slippery, the surface is slightly scratched, and the pattern and characters are slightly damaged.
Evaluation C: The nib is difficult to slip or the nib bites into the hook and cannot draw a line. When a line is drawn with a large force, the surface is markedly damaged, and the pattern and characters are significantly damaged.

[Beauty of insulated paper container]
The insulated paper container provided with the member formed from the multilayer sheet for insulated paper containers of this invention is excellent in cosmetics. The cosmetic properties of the insulated paper container can be evaluated by the clarity of letters and colors. Specifically, evaluation is performed based on the character and color clarity of the insulated paper container by a comparison test by 10 evaluators. That is, a heat insulating paper container (hereinafter referred to as “control container”) having a member formed from a heat insulating paper container of the present invention and a multilayer sheet for a heat insulating paper container that does not have the low melting point thermoplastic resin layer (A) used as a control. Are placed side by side on a desk under a fluorescent lamp, and the evaluation results of the majority of the evaluators are based on the results of visual evaluation from a position 50 cm away from the insulation paper container. Assess character and color clarity. The evaluation criteria of the character and color clarity of the insulated paper container are as follows. If the evaluation of the character and color clarity of the insulated paper container is A, the cosmetic property of the insulated paper container is A and On the other hand, if the evaluation of character and color definition is B, the cosmetic property of the insulated paper container is evaluated as B. The heat insulating paper container of the present invention has a cosmetic evaluation of A.
<Evaluation criteria for character and color clarity>
Evaluation A: Characters and colors appear clearer than the control container.
Evaluation B: Letters and colors appear clearer in the control container.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely, the present invention is not limited only to these examples. The characteristics of the insulated paper container were measured by the following method.

[Glossiness of insulated paper container]
The glossiness of the insulated paper container is a winch constant temperature dryer winch manufactured by Tokyo Rika Machinery Co., Ltd., which is a multilayer sheet for insulated paper containers cut into a square 150 mm wide x 150 mm long as an alternative to the insulated paper container. Using Deo oven WFO-601SD type (turntable installation type), the multilayer sheet is placed on the turntable with the foamable low-melting point thermoplastic synthetic resin layer (C) as the upper surface, and the temperature is 130 ° C. It measured using the sample sheet for glossiness evaluation (multi-layer sheet made of heat insulation paper) prepared by heating and foaming for a minute. That is, a sample is cut out from the sample sheet for glossiness evaluation (multilayer sheet made of heat insulating paper) into a size of width 100 mm × length 100 mm, placed on a flat plate, and using a gloss meter, the incident angle and Measurements were made in the length direction and width direction with both reflection angles being 60 °. As the measurement points of the glossiness, the measurement was performed on five white background portions where color printing was not performed, and the average value of n = 5 was defined as the glossiness of the insulated paper container.

[Solvent resistance of insulated paper containers]
The chemical resistance of the insulated paper container was evaluated for four types of solvents, methyl ethyl ketone, ethyl acetate, ethanol and toluene. Specifically, a sample is cut out in a size of 10 cm in width and 10 cm in length including a portion printed in red from a heat-insulated paper container, placed on a flat plate, and a portion printed in red One drop of each solvent was dropped on the outer surface of each using a syringe, and after 10 seconds, the surface of the red printed portion was visually observed to evaluate the solvent resistance against each solvent. The evaluation criteria were as follows.
<Evaluation criteria>
Evaluation A: There is no bleeding of the solvent on the surface, the pattern and characters are not damaged by the solvent, and the surface gloss is not changed.
Evaluation B: There is a slight blur of the solvent on the surface, and the pattern and characters are slightly damaged by the solvent.
Evaluation C: Red printing ink is melted and pattern / character damage is observed.

[Scratch resistance of insulated paper containers]
The scratch resistance of the insulated paper container is cut out from the insulated paper container to a size of 10 cm wide × 20 cm long and placed on a flat plate. Ten evaluators are black on the outer surface of the insulated paper container. Based on the results of each evaluator evaluating the ease of drawing a line when drawing a straight line with a length of about 10 cm with a ballpoint pen according to the following criteria, the evaluation results of the majority of evaluators were evaluated as the scratch resistance of the insulated paper container. It was sex.
<Evaluation criteria>
Evaluation A: The tip of the pen is slippery, the surface is not scratched at all, and the pattern and characters are not damaged.
Evaluation B: The nib is caught slightly slippery, the surface is slightly scratched, and the pattern and characters are slightly damaged.
Evaluation C: The nib is difficult to slip or the nib bites into the hook and cannot draw a line. When a line is drawn with a large force, the surface is markedly damaged, and the pattern and characters are significantly damaged.

[Beauty of insulated paper container]
The cosmetic property of the insulated paper container was evaluated by the character and color clarity of the insulated paper container by a comparison test by 10 evaluators. Specifically, a heat insulating paper container and a heat insulating paper container of Comparative Example 1 (described later) formed from a multilayer sheet for a heat insulating paper container that does not include the low-melting point thermoplastic resin layer (A). "Corresponding to the" control container "), placed side by side on a desk under a fluorescent lamp, and the evaluation results of the majority of the evaluators based on the result of visual comparison and evaluation from a position 50 cm away from the heat insulating paper. It was set as the evaluation of the character of a container made, and the clarity of a color. The evaluation criteria were as follows. If the evaluation of the character and color definition of the insulated paper container is A, the cosmetic property of the insulated paper container is evaluated as A, while if the evaluation of the character and color definition is B, the insulated paper The cosmetic property of the container made was evaluated as B.
<Evaluation criteria for character and color clarity>
Evaluation A: Characters and colors appear clearer than the control container.
Evaluation B: Letters and colors appear clearer in the control container.

[Heat sealability of multilayer sheet for insulated paper containers]
The heat sealability of the multilayer sheet for insulating paper containers was measured and evaluated by the methods 1) to 3) below using the above-described glossiness evaluation sample sheet (insulating paper multilayer sheet) as a sample.
<Measurement of heat sealability>
1) TP-701-G heat sealer (heat gradient) manufactured by Tester Sangyo Co., Ltd. as a heat sealer using the thermoplastic resin layer (E) and the low-melting point thermoplastic resin layer (A) of the multilayer sheet made of heat insulating paper as a sample. ), And using a seal bar having a width of 10 mm and a length of 50 mm, heat sealing was performed at a set temperature and a seal pressure of 1 kN for 2 seconds, and then STA1150 manufactured by A & D Corporation was used as a tensile tester. In use, a tensile test was performed under the material fracture conditions described below, and the material fracture temperature was measured.
2) Insulated paper multilayer sheet prepared from a multilayer sheet for insulated paper containers that does not have the low-melting point thermoplastic resin layer (A) used to form the insulated paper container of Comparative Example 1 described later as a control sheet After performing heat sealing under the same conditions as in 1), a tensile test was performed under the above material fracture conditions, and the material fracture temperature of the control sheet was measured. At that time, the control sheet not provided with the low melting point thermoplastic resin layer (A) does not form the printing layer (B) at the place where heat sealing is performed according to a conventional method. The layer (C) (already foamed) was exposed, and the exposed foamable low-melting-point thermoplastic resin layer (C) and the thermoplastic resin layer (E) were heat-sealed.
3) Based on the heat seal temperature difference between the material destruction temperature of the multilayer sheet for insulated paper containers as a sample and the material destruction temperature of the control sheet, the low temperature heat sealability was evaluated according to the following criteria.
<Material destruction conditions>
Sample size: width 15 mm, length 50 mm (cut into a rectangle along the heat seal part)
Distance between chucks: 25mm
Tensile speed: 200 mm / min Peeling form: 180 degree peeling <Evaluation criteria for low temperature heat sealability>
A: The heat seal temperature difference is 15 ° C. or higher (heat seal can be performed at a lower temperature).
B: The heat seal temperature difference is 5 ° C. or more and less than 15 ° C. (can be heat sealed at a slightly low temperature).
C: The heat seal temperature difference is less than 5 ° C. or the material destruction temperature is higher than that of the control sheet.

[Example 1]
[Formation of thermoplastic resin layer (E)]
As a paper substrate (D), a cup base paper (basis weight 300 g / m ² , thickness 335 μm, moisture content 6-9 mass%) manufactured by Nippon Paper Industries Co., Ltd. was unwound from a base paper roll. Medium density polyethylene (manufactured by Tosoh Corporation, density 940 kg / m ³ ) using an extrusion laminator (manufactured by Sumitomo Heavy Industries Modern Co., Ltd., aperture 115 mm) provided with a T die on the upper surface of the paper substrate (D). Melting point 133 ° C., MFR 6.5 g / 10 min., Hereinafter referred to as “MDPE”) is extruded at an extrusion temperature of 300 to 350 ° C. and spread in layers so as to cover the paper substrate (D). A thermoplastic resin layer (E) having a thickness of 40 μm was formed by passing between a cooling roll having a surface temperature of 20 ° C. and a pressure-bonding roll having a surface temperature of 30 ° C. for cooling.

[Formation of foamable low melting point thermoplastic resin layer (C)]
Low-density polyethylene (Tosoh) using an extrusion laminator (Sumitomo Heavy Industries Modern Co., Ltd., diameter 90 mm) equipped with a T-die on the surface of the paper substrate (D) opposite to the thermoplastic resin layer (E) Made by Co., Ltd. Density 918 kg / m ³ , melting point 103 ° C., MFR 15 g / 10 minutes (hereinafter sometimes referred to as “LDPE-1”) is extruded at an extrusion temperature of 300 to 350 ° C. to make a paper substrate (D) After being spread in a layer so as to cover, it is cooled by passing between a cooling roll having a surface temperature of 20 ° C. and a pressure roll having a surface temperature of 30 ° C., thereby foaming a low-melting-point thermoplastic resin layer (C ) Was formed.

[Formation of printing layer (B)]
In order to increase the adhesive strength with the printing layer (B), the upper surface of the foamable low melting point thermoplastic resin layer (C) is subjected to corona discharge treatment, and then a gravure printing machine (Fuji Kikai Kogyo Co., Ltd., 7-color printing). Specification), a solid white printing ink (Prime Cup (registered trademark) 63C white, manufactured by Toyo Ink Co., Ltd.) is applied to a coating amount of 2.5 g / m ² after drying, and the thickness is 2.5 μm. The solid printing layer (B2) was formed. Next, using the gravure printing machine, the red ink [Prime Cup (registered trademark) 3S, manufactured by Toyo Ink Co., Ltd.] was applied in a pattern so that the coating amount after drying was 0.375 g / m ² , By forming a pattern printing layer (B1) having a thickness of 2.5 μm, a printing layer (B) composed of a solid printing layer (B2) and a pattern printing layer (B1) was formed.

[Formation of low melting point thermoplastic resin layer (A)]
Using an extrusion laminator (Sumitomo Heavy Industries Modern Co., Ltd., caliber 90 mm) having a T-die on the upper surface of the pattern printing layer (B1) of the printing layer (B), the LDPE-1 is extruded at a temperature of 300. Thickness of 15 μm by extruding at ˜350 ° C. and spreading in layers so as to cover the printing layer (B), and then passing between a cooling roll having a surface temperature of 20 ° C. and a pressure roll having a surface temperature of 30 ° C. By forming the low-melting-point thermoplastic resin layer (A), a multilayer sheet for insulated paper containers was produced. The produced low melting point thermoplastic resin layer (A), printing layer (B), foamable low melting point thermoplastic resin layer (C), paper substrate (D) and thermoplastic resin layer (E) About the multilayer sheet | seat for insulated paper containers with which it equips in order, the heat sealing property was evaluated by measuring material destruction temperature.

(Forming the body member)
The obtained multilayer sheet for insulated paper containers was punched into a fan shape corresponding to the developed shape of the container body member to obtain a body member for the insulated paper container.

[Heat seal]
The body member of the obtained heat insulating paper container is rolled up and the both side ends are overlapped with a width of 10 mm [the low melting point thermoplastic resin layer (A) on one side end and the thermoplastic resin layer (E on the other side end) ) Abut. ] By using a TP-701-G heat sealer (thermal gradient type) manufactured by Tester Sangyo Co., Ltd., heat sealed for 2 seconds at a temperature of 185 ° C. and a seal pressure of 1 kN, thereby forming a substantially frustoconical insulated paper container The torso was formed. Next, the formed body portion is formed by separately forming a bottom member of a circular heat insulating paper container formed separately [in the heat insulating paper container multilayer sheet obtained above, the printing layer (B) is formed only from the solid printing layer (B2). Corresponds to what is formed. ] Was heat-sealed, and the heat-sealed portion was rolled up to obtain a container-shaped assembly.

[Formation of insulated paper containers]
The obtained container-shaped assembly is placed in a heating furnace at a temperature of 130 ° C. and heated for 5 minutes to evaporate the water contained in the paper substrate (D) and to produce a low melting point heat capable of foaming. The plastic resin layer (C) was foamed to produce a heat insulating paper container. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Comparative Example 1] (Manufacture of control sheet and control container)
A multilayer sheet for insulated paper containers without a low-melting point thermoplastic resin layer (A) was produced in the same manner as in Example 1 except that the low-melting point thermoplastic resin layer (A) was not formed. A control sheet was used. In addition, the printing layer (B) was not formed in the location utilized as a heat seal part of the low melting point thermoplastic resin layer (C) which can be foamed. Subsequently, the control sheet was punched into a fan shape corresponding to the developed shape of the container body member to obtain a body member of the insulated paper container, and then a container-shaped assembly was obtained in the same manner as in Example 1. . In addition, the same bottom member as used in Example 1 was used for the bottom member. Next, in the same manner as in Example 1, the foamable low melting point thermoplastic resin layer (C) was foamed to produce a heat-insulated paper container, which was used as a control container. About the manufactured control container, glossiness, solvent resistance, and scratch resistance were measured and evaluated, and used as a standard for evaluation of cosmetics. The results are shown in Table 1 together with the evaluation results of the heat sealability of the control sheet.

[Example 2]
The same as in Example 1 except that the low melting point thermoplastic resin layer (A) having a thickness of 20 μm was formed by changing the supply amount of LDPE-1 to the extrusion laminator equipped with a T die and the extrusion speed. A low-melting point thermoplastic resin layer (A), a printing layer (B), a foamable low-melting point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) in this order. A multilayer sheet for insulated paper containers was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out in a fan shape to obtain a body member of the heat insulating paper container, and then a container-shaped assembly was obtained in the same manner as in Example 1. In addition, the same bottom member as used in Example 1 was used for the bottom member. Next, in the same manner as in Example 1, the foamable low melting point thermoplastic resin layer (C) was foamed to produce a heat insulating paper container. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 3]
Example 1 except that a foamable low-melting-point thermoplastic resin layer (C) having a thickness of 30 μm was formed by changing the supply amount and extrusion rate of LDPE-1 to an extrusion laminator equipped with a T die. Similarly, a low-melting point thermoplastic resin layer (A), a printing layer (B), a foamable low-melting point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E), A multilayer sheet for insulated paper containers provided in this order was manufactured. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 1. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 4]
Example 1 except that the foaming low-melting point thermoplastic resin layer (C) having a thickness of 70 μm was formed by changing the supply amount of LDPE-1 to the extrusion laminator equipped with a T die and the extrusion speed. Similarly, a low-melting point thermoplastic resin layer (A), a printing layer (B), a foamable low-melting point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E), A multilayer sheet for insulated paper containers provided in this order was manufactured. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 1. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 5]
Low melting point thermoplasticity in the same manner as in Example 3, except that a glass base paper (thickness: 357 μm, moisture content: 6-9 mass%) having a basis weight of 320 g / m ² was used as the paper substrate (D). For insulated paper containers comprising a resin layer (A), a printing layer (B), a foamable low-melting point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) in this order. A multilayer sheet was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out in a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 3. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 6]
The low-melting point thermoplastic resin layer (A), the printing layer (B), and foaming were performed in the same manner as in Example 1 except that the cup base paper used in Example 5 was used as the paper substrate (D). A multilayer sheet for a heat-insulating paper container having a possible low-melting-point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) in this order was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 1. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 7]
The low melting point thermoplastic resin layer (A), the printing layer (B), and the foaming are the same as in Example 4 except that the cup base paper used in Example 5 was used as the paper substrate (D). A multilayer sheet for a heat-insulating paper container having a possible low-melting-point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) in this order was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 4. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 8]
Low-melting point thermoplastic resin layer (A) is made of low-density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., density 918 kg / m ³ , melting point 106 ° C., MFR 14 g / 10 min., Hereinafter sometimes referred to as “LDPE-2”). A low-melting-point thermoplastic resin layer (A), a printing layer (B), a foamable low-melting-point thermoplastic resin layer (excluding being formed by extrusion at an extrusion temperature of 300 to 350 ° C.) C) A multilayer sheet for a heat insulating paper container provided with a paper base (D) and a thermoplastic resin layer (E) in this order was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 1. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 9]
The low melting point thermoplastic resin layer (A) was mixed with the LDPE-1 and ethylene / α-olefin copolymer [Nipolon (registered trademark) -LY15A manufactured by Tosoh Corporation. Density 912 kg / m ³ , melting point 103 ° C., MFR 15.0 g / 10 min. Hereinafter, it may be referred to as “LLDPE”. The composition comprising: (mass ratio 80:20; hereinafter referred to as “LLDPE mixing”) was formed by extrusion at an extrusion temperature of 300 to 350 ° C., in the same manner as in Example 1. A low-melting point thermoplastic resin layer (A), a printing layer (B), a foamable low-melting point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) in this order. A multilayer sheet for insulated paper containers was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 1. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 10]
A foamable low-melting-point thermoplastic resin layer (C) is extruded from a composition comprising the LDPE-1 and the LLDPE ("LLDPE mixture" having a mass ratio of 80:20) at an extrusion temperature of 300 to 350 ° C. The low melting point thermoplastic resin layer (A), the printing layer (B), the foamable low melting point thermoplastic resin layer (C), and the paper base ( A multilayer sheet for a container made of heat-insulating paper having D) and a thermoplastic resin layer (E) in this order was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 9. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 11]
The low melting point thermoplastic resin layer (A), the printing layer (B), and the foaming are the same as in Example 8, except that the cup base paper used in Example 5 was used as the paper substrate (D). A multilayer sheet for a heat-insulating paper container having a possible low-melting-point thermoplastic resin layer (C), a paper substrate (D), and a thermoplastic resin layer (E) in this order was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 8. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 12]
As the barrier layer (F), an aluminum oxide vapor-deposited PET film (manufactured by Toray Industries, Inc .; hereinafter referred to as “deposited PET”) having a thickness of 12 μm is used, and an adhesive layer made of maleic anhydride-modified polyethylene on both sides. [Mitsui Chemicals Co., Ltd., Admer (registered trademark) NE827, melting point 124 ° C.] were coextruded to a thickness of 15 μm and then adhered to the paper substrate (D). Next, except that the thermoplastic resin layer (E) was formed on the surface opposite to the paper substrate (D) of the barrier layer (F) laminated with the paper substrate (D), In the same manner as in Example 1, the low-melting point thermoplastic resin layer (A), the printing layer (B), the foamable low-melting point thermoplastic resin layer (C), the paper substrate (D), the adhesive layer, and the barrier A multilayer sheet for insulated paper containers comprising the layer (F), the adhesive layer and the thermoplastic resin layer (E) in this order was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 1. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

[Example 13]
As the barrier layer (F), a 12 μm-thick acrylic acid-based barrier resin-coated PET film [manufactured by Kureha Co., Ltd., Besera (registered trademark) ET-14R Hereinafter, it may be referred to as “acrylic coat”. The low-melting point thermoplastic resin layer (A), the printing layer (B), the foamable low-melting point thermoplastic resin layer (C), and the paper substrate, in the same manner as in Example 12, except that A multilayer sheet for a heat-insulating paper container having (D), an adhesive layer, a barrier layer (F), an adhesive layer, and a thermoplastic resin layer (E) in this order was produced. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape to obtain a body member of the heat insulating paper container, and then a heat insulating paper container was manufactured in the same manner as in Example 12. The manufactured insulated paper container was measured and evaluated for glossiness, solvent resistance, scratch resistance, and cosmetics. These results are shown in Table 1 together with the evaluation results of the heat sealability of the multilayer sheet for insulated paper containers.

  From Table 1, the low-melting point thermoplastic resin layer (A), the printing layer (B) (specifically, the pattern printing layer (B1) and the solid printing layer (B2)), the foamable low-melting point thermoplastic resin The multilayer sheet for heat-insulating paper containers of Examples 1 to 11 provided with the layer (C), the paper base (D) and the thermoplastic resin layer (E) in this order is excellent in heat sealability, Moreover, it turned out that all the insulated paper containers provided with the member formed from these multilayer sheets for insulated paper containers are excellent in glossiness, solvent resistance, scratch resistance, and cosmetics.

  Furthermore, the low melting point thermoplastic resin layer (A), the printing layer (B), the foamable low melting point thermoplastic resin layer (C), the paper substrate (D) and the thermoplastic resin layer (E) are arranged in this order. In addition, the multilayer sheets for insulated paper containers of Examples 12 and 13 having a barrier layer (F) between the paper substrate (D) and the thermoplastic resin layer (E) are excellent in heat sealability. In addition, all of the barrier insulating paper containers provided with the members formed from the multilayer sheet for insulating paper containers are excellent in gloss, solvent resistance, scratch resistance and cosmetics. I found out.

  On the other hand, the heat-insulating paper container multilayer sheet of Comparative Example 1 that does not have the low-melting point thermoplastic resin layer (A) is inferior in heat sealability as compared with the heat-insulating paper container multilayer sheet of the present invention. In addition, a heat insulating paper container provided with a member formed from the multilayer sheet for heat insulating paper containers is inferior in glossiness, solvent resistance, scratch resistance and cosmetic properties as compared with the heat insulating paper container of the present invention. It turned out to be a thing.

[Example 14]
In order to increase the adhesive strength with the printing layer (B), the upper surface of the thermoplastic resin layer (E) is subjected to corona discharge treatment, and then a solid printing layer (B2) having a thickness of 2.5 μm is formed, and then the thickness is increased. Except that the printed layer (B) composed of the solid printed layer (B2) and the patterned printed layer (B1) was formed by forming the 2.5 μm patterned printed layer (B1), the same as in Example 1. The low-melting point thermoplastic resin layer (A), the printing layer (B), the thermoplastic resin layer (E), the paper substrate (D) and the foamable low-melting point thermoplastic resin layer (C) are arranged in this order. A multilayer sheet for insulated paper containers provided was manufactured. Subsequently, the multilayer sheet for a heat insulating paper container was punched out into a fan shape corresponding to the developed shape of the body member of the container to obtain the body member of the heat insulating paper container. A container was manufactured. The heat-insulated paper container multilayer sheet obtained is excellent in heat-sealability, and all of the heat-insulated paper containers provided with members formed from these heat-insulated paper container multilayer sheets are glossy. It was excellent in solvent resistance, scratch resistance and cosmetics.

  According to the present invention, the low-melting point thermoplastic resin layer (A), the printing layer (B), the foamable low-melting point thermoplastic resin layer (C), the paper substrate (D), and the thermoplastic resin layer (E). A multilayer sheet for insulated paper containers characterized by comprising a printed layer, a paper substrate, a thermoplastic resin layer, and a foamable low-melting point thermoplastic resin layer. In the multilayer sheet, since it is possible to provide a heat-insulating paper container having a clear print, a beautiful surface, and excellent scratch resistance and hygiene, the industrial applicability is high.

  Furthermore, according to the present invention, a method for easily manufacturing the multilayer sheet for a heat insulating paper container and the heat insulating paper container is provided, so that industrial applicability is high.

1: Low melting point thermoplastic resin layer (A)
2: Print layer (B)
3: Foamable low melting point thermoplastic resin layer (C)
4: Paper base material (D)
5: Thermoplastic resin layer (E)
X: Insulated paper container a: Body member b: Bottom member

Claims (16)

A low-melting point thermoplastic resin layer (A), a printing layer (B), a foamable low-melting point thermoplastic resin layer (C), a paper substrate (D) and a thermoplastic resin layer (E) are provided in this order , The difference in melting point between the thermoplastic resin forming the low melting thermoplastic resin layer (A) and the thermoplastic resin forming the foamable low melting thermoplastic resin layer (C) is less than 5 ° C. Multi-layer sheet for insulated paper containers.   The printing layer (B) includes a pattern printing layer (B1) adjacent to the low melting point thermoplastic resin layer (A) and a solid printing layer (B2) on the opposite side of the low melting point thermoplastic resin layer (A). The multilayer sheet for insulated paper containers according to claim 1.   The multilayer sheet for insulated paper containers according to claim 1 or 2, wherein the foamable low-melting point thermoplastic resin layer (C) is foamed by evaporation of moisture contained in the paper substrate (D). The thermoplastic resin forming the low melting thermoplastic resin layer thermoplastic resin and foamable low melting thermoplastic resin layer to form a (A) (C) is any one of claims 1 to 3 is a different thermoplastic resin The multilayer sheet for heat-insulated paper containers as described in Item 1. The resin forming the low-melting-point thermoplastic resin layer (A), the foamable low-melting-point thermoplastic resin layer (C), and the thermoplastic resin layer (E) is polyolefin, according to any one of claims 1 to 4. The multilayer sheet for insulated paper containers as described. Resin that forms the low melting point thermoplastic resin layer (A) or foamable low melting point thermoplastic resin layer (C) is low density polyethylene (LDPE), linear low density polyethylene (LLDPE), The resin comprising a combination of one or more selected from the group consisting of very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene, and polymethylpentene. The multilayer sheet for heat-insulating paper containers as described in any one of 1 to 5.   The multilayer sheet for insulated paper containers according to any one of claims 1 to 6, wherein the low-melting-point thermoplastic resin layer (A) is formed from a thermoplastic resin containing a matting agent.   The multilayer sheet for insulated paper containers according to any one of claims 1 to 7, further comprising a barrier layer (F) between the paper substrate (D) and the thermoplastic resin layer (E).   The multilayer sheet for insulated paper containers according to claim 8, wherein the barrier layer (F) is laminated with one or both of the paper substrate (D) and the thermoplastic resin layer (E). On the surface of the printed layer (B) of the multilayer sheet comprising the printed layer (B), a foamable low melting point thermoplastic resin layer (C), a paper substrate (D) and a thermoplastic resin layer (E), The manufacturing method of the multilayer sheet for insulated paper containers of any one of Claims 1 thru | or 9 including the process of melt-coating a low melting-point thermoplastic resin and forming a low-melting-point thermoplastic resin layer (A). Including a step of forming a printed layer (B) on the surface of a multilayer sheet comprising a foamable low-melting-point thermoplastic resin layer (C), a paper substrate (D) and a thermoplastic resin layer (E) in this order , The manufacturing method of the multilayer sheet | seat for heat-insulating paper containers of any one of Claims 1 thru | or 9 . Low-melting-point thermoplastic that can be foamed on the surface opposite to the thermoplastic resin layer (E) of the paper substrate (D) of the multilayer sheet comprising the paper substrate (D) and the thermoplastic resin layer (E) The manufacturing method of the multilayer sheet for insulated paper containers of Claim 10 or 11 including the process of forming a resin layer (C). By including the step of laminating the barrier layer (F) with one or both of the paper substrate (D) and the thermoplastic resin layer (E) by adhesion, the paper substrate (D) and the thermoplastic resin layer ( The manufacturing method of the multilayer sheet for insulated paper containers as described in any one of Claims 10 thru | or 12 provided with a barrier layer (F) between E). A heat-insulating paper container comprising a member formed from the multilayer sheet for heat-insulating paper containers according to any one of claims 1 to 9 . A heat-insulating paper container comprising a trunk member and / or a bottom member formed from the multilayer sheet for heat-insulating paper container according to any one of claims 1 to 9 . The manufacturing method of the insulated paper container of Claim 14 or 15 including the process of heat-sealing the edge part of the multilayer sheet for insulated paper containers of any one of Claims 1 thru | or 9 .

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