JP2017159564A - Paper base material for foamed heat-insulation paper container, sheet for foamed heat-insulation paper container, and foamed heat-insulation paper container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamed heat-insulation paper container which reduces variations in a place of a permeation amount of water vapor generated from a paper base material, uniformly foams a thermoplastic resin layer, and thereby is excellent in heat insulation and appearance of the surface, and to provide a paper base material for foamed heat-insulation paper container and a sheet for foamed heat-insulation paper container used in the production.SOLUTION: A paper base material 3 for foamed heat-insulation paper container has an ethylene-modified polyvinyl alcohol layer 2 on at least one surface of a paper base material 1. A sheet for foamed heat-insulation paper container has an ethylene-modified polyvinyl alcohol layer between a paper base material and a thermoplastic resin layer. A foamed heat-insulation paper container uses foamed heat-insulation paper in at least one of a body member and a bottom plate member, and the foamed heat-insulation paper has a foamed resin layer formed from a thermoplastic resin on at least one surface of a paper base material, and has an ethylene-modified polyvinyl alcohol layer between the paper base material and the foamed resin layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a foam heat insulating paper container, a foam heat insulating paper container paper base used in the production thereof, and a sheet for a foam heat insulating paper container.

  Insulating containers are widely used as containers to provide buyers with hot drinks such as coffee and soup in fast food restaurants, trains, and vending machines, or as cups of instant ramen. It is used.

  Conventionally, as a heat-insulating container used for such an application, a container made of expanded polystyrene is known. The foamed polystyrene container is manufactured by injecting a raw material obtained by adding a foaming agent to polystyrene into a mold, applying heat and pressure to the raw material, and foaming and molding the raw material. The foamed polystyrene container thus obtained has a problem that the amount of trash after use is large although the entire container is foamed, which is bulky and very excellent in heat insulation. is there. In addition, since the expanded polystyrene container generates high heat when incinerated, there is a concern about the influence on the incinerator. In addition, the review of its use is also required from the viewpoint of saving oil resources.

  Further, since there are many minute irregularities on the outer surface of the expanded polystyrene container, there is a problem that even if patterns, characters, symbols, etc. are printed on the outer surface of the container, it is difficult to express clearly. Furthermore, since the strength is weaker than that of a paper heat insulating container, there is a problem that a relatively large container for instant ramen with a cup breaks during transportation.

  Several prior arts have been disclosed for these problems. Patent Document 1 discloses a technique in which a paper container laminated with a thermoplastic synthetic resin film such as polyethylene is heated, and the film is foamed using moisture contained in the paper. Patent Document 2 discloses a paper container on which a two-layer structure heat insulating film composed of a foamed inner layer of a thermoplastic resin having a low melting point and a non-foamed outer layer of a thermoplastic resin having a higher melting point is attached. It is disclosed. Patent Document 3 discloses a foam insulation paper container sheet in which a thermoplastic resin layer such as polyethylene is laminated on at least one side of a paper base, and the surface of the paper base is processed by a calendar size press. An insulating paper container sheet is disclosed.

JP-A-57-110439 JP-A-5-42929 JP 2012-214038 A

  Since the main body of the base material of the container described in Patent Document 1 and Patent Document 2 is paper, the amount of petroleum used is small and the environmental load is small compared to a container made entirely of expanded polystyrene. However, the containers described in Patent Document 1 and Patent Document 2 have a variation in the amount of water vapor generated from the paper base material depending on the location. There was a problem of lack of beauty.

  In the foam insulated paper container described in Patent Document 3, although the environmental load is small for the same reason, the amount of water vapor generated from the paper base material during heating and foaming is not uniform depending on the location. The foaming was non-uniform, and there was room for improvement in surface aesthetics.

  The present invention has been made in view of the above situation. That is, the present invention is a foam insulated paper container that is excellent in heat insulation and surface aesthetics by reducing variation in the amount of permeation of water vapor generated from a paper base material and uniformly foaming a thermoplastic resin layer. It is an issue to provide. It is another object of the present invention to provide a foam insulating paper container sheet base material and a foam insulating paper container sheet used for manufacturing the foam insulating paper container.

The present inventors have studied a surface treatment method for a paper substrate before laminating a thermoplastic resin layer to be a foamed resin layer. As a result, when an ethylene-modified polyvinyl alcohol layer is provided in advance on the surface of the paper substrate, the water vapor generated from the paper substrate is appropriately blocked to prevent the water vapor from being ejected from a specific location. It was found that the variation in the amount of transmitted light can be reduced. And it discovered that the heat insulation and beauty of a foam heat insulation paper container could be improved by that, and came to complete this invention.
The present invention has the following configuration.

(1) A foam insulated paper container paper substrate having an ethylene-modified polyvinyl alcohol layer on at least one side of the paper substrate.

(2) The foam insulation paper container base material according to (1), wherein the air resistance per basis weight is 0.3 to 2.0 s / g / m ² .

(3) The foam insulated paper container base material according to (1) or (2), wherein the amount of the ethylene-modified polyvinyl alcohol layer formed is 0.2 to 4.0 g / m ^{2 on} one side.

(4) The foam insulating paper container paper base material according to any one of (1) to (3), wherein the density is 0.60 to 0.99 g / m ³ .

(5) The foam insulated paper container base material according to any one of (1) to (4), wherein the moisture content is 5 to 60 g / m ² .

(6) A sheet for a foam insulated paper container having a thermoplastic resin layer on at least one side of a paper base material, and having an ethylene-modified polyvinyl alcohol layer between the paper base material and the thermoplastic resin layer. A sheet for foam insulated paper containers.

(7) The sheet for a foam insulated paper container according to (6), wherein the thermoplastic resin layer has a thickness of 30 to 80 μm.

(8) The foam insulating paper container sheet according to (6) or (7), wherein the thermoplastic resin is polyethylene.

(9) A foam heat insulating paper container using foam heat insulating paper for at least one of a body member and a bottom plate member, wherein the foam heat insulating paper has a foam resin layer made of a thermoplastic resin on at least one side of a paper substrate. A foam insulated paper container having an ethylene-modified polyvinyl alcohol layer between the paper substrate and the foamed resin layer.

  Since the foamed heat insulating paper container of the present invention has little variation depending on the location of the permeation amount of water vapor generated from the paper base material, the thermoplastic resin layer is uniformly foamed, and is excellent in heat insulating properties and surface aesthetics. In addition, since the sheet of the foam insulated paper container and the sheet for the foam insulated paper container of the present invention has little variation depending on the location of the permeation amount of water vapor generated from the paper substrate, the thermoplastic resin layer is uniformly foamed and insulated. Foamed insulated paper container having excellent properties and surface aesthetics.

It is typical sectional drawing of the foam insulation paper container paper base material of this embodiment. It is typical sectional drawing of the sheet | seat for foam insulation paper containers of this embodiment. It is typical sectional drawing of the foam insulation paper container of this embodiment. It is an expanded sectional view of the part shown by A of FIG.

  Embodiments of the present invention will be described below. However, embodiments of the present invention are not limited to the following embodiments.

  FIG. 3 is a schematic cross-sectional view of the foam insulated paper container of the present embodiment. 4 is an enlarged cross-sectional view of a portion indicated by A in FIG. In this embodiment, the foam insulation paper container 8 is a foam insulation paper container 8 using foam insulation paper for at least one of the body member 6 and the bottom plate member 7, and the foam insulation paper container is at least of the paper substrate 1. One side has a foamed resin layer 9 made of a thermoplastic resin. The foam heat insulating paper container 8 of this embodiment is characterized by having an ethylene-modified polyvinyl alcohol layer 2 between the paper substrate 1 and the foamed resin layer 9. In FIG. 4, the ethylene-modified polyvinyl alcohol layer 2 is formed on both sides of the paper substrate 1. Further, the foam insulated paper container 8 has a foamed resin layer 9 on the outer wall surface side, and has a high melting point thermoplastic resin layer 10 to be described later on the inner wall surface side.

  FIG. 2 is a schematic cross-sectional view of the sheet for foamed heat-insulating paper container of the present embodiment. The foam insulated paper container sheet 5 of the present embodiment is used for manufacturing the foam insulated paper container 8 described above. The sheet 5 for a foam insulated paper container according to this embodiment has a thermoplastic resin layer 4 on at least one surface of a paper substrate 1, and ethylene-modified polyvinyl between the paper substrate 1 and the thermoplastic resin layer 4. It has an alcohol layer 2. The thermoplastic resin layer 4 is foamed by heat treatment to become a foamed resin layer 9.

  FIG. 1 is a schematic cross-sectional view of a foam insulated paper container paper base material according to the present embodiment. The foam insulated paper container 3 of the present embodiment is used for producing the foam insulated paper container sheet 5 described above. The foam insulated paper container paper substrate 3 of this embodiment has an ethylene-modified polyvinyl alcohol layer 2 on at least one surface of the paper substrate 1. By providing the thermoplastic resin layer 4 on the ethylene-modified polyvinyl alcohol layer 2, the above-mentioned foamed insulated paper container sheet 5 is formed.

  A paper container is formed by using the foam insulating paper container sheet 5 for the body member 6 and the bottom plate member 7. Thereafter, by heating the paper container, moisture contained in the paper substrate 1 and the ethylene-modified polyvinyl alcohol layer 2 is vaporized to become water vapor. The generated water vapor passes through the ethylene-modified polyvinyl alcohol layer 2 and penetrates into the heated thermoplastic resin layer 4 to foam the thermoplastic resin, so that the thermoplastic resin layer 4 is changed into a foamed resin layer 9. . As a result, the paper container becomes a foam heat insulating paper container 8 having heat insulating properties.

  According to the study by the present inventors, when a film made of a resin or the like is not formed on the surface of the paper substrate 1, when heated, the water vapor is directly released from the paper substrate 1, so It becomes non-uniform depending on the location of the paper substrate 1 and tends to cause partial overfoaming in the foaming of the thermoplastic resin layer 4. If there is an excessively foamed portion, the foamed form becomes non-uniform and irregularities are generated on the surface, so that both the heat insulation and the surface aesthetics are lowered.

As a result of repeated studies on the film material formed on the surface of the paper substrate 1, the present inventors have found that ethylene-modified polyvinyl alcohol is excellent as a film material.
Hereinafter, each member which comprises this embodiment is demonstrated.

(Ethylene-modified polyvinyl alcohol)
Ethylene-modified polyvinyl alcohol is polyvinyl alcohol modified by introducing an ethylene group into the main chain in polyvinyl alcohol. The reason why ethylene-modified polyvinyl alcohol is excellent as a film material to be formed on a paper substrate is considered as follows.

  Ethylene-modified polyvinyl alcohol has an appropriate coexistence of hydrophilic and hydrophobic functional groups in the polymer molecule. Is also excellent. When a film of ethylene-modified polyvinyl alcohol that is firmly adhered to a paper substrate is formed, it is possible to appropriately control the amount of water vapor permeated and to prevent the amount of water vapor permeation from varying depending on the location. As a result, the foamed state of the thermoplastic resin layer can be made uniform, and the heat insulation can be improved.

  Further, the ethylene-modified polyvinyl alcohol can change the balance between hydrophilicity and hydrophobicity by changing the degree of ethylene modification, and can control the water vapor barrier performance more precisely. The degree of ethylene modification of ethylene-modified polyvinyl alcohol is represented by mol% of ethylene units with respect to the entire monomer units (ethylene units + vinyl alcohol units). However, vinyl alcohol units include unsaponified vinyl acetate units. The ethylene modification degree is preferably 2 to 12 mol%, more preferably 4 to 8 mol%. Such ethylene-modified polyvinyl alcohol is commercially available, for example, as “Exeval” series manufactured by Kuraray Co., Ltd., and can be easily obtained and used.

  The average degree of polymerization of the ethylene-modified polyvinyl alcohol is preferably 800 to 1500 when measured according to JIS K 6726-1994. By setting the average degree of polymerization to 800 or more, film formability is improved. On the other hand, when the average degree of polymerization is 1500 or less, solubility in water is improved, the solution viscosity is not increased, and coating becomes easy.

  The saponification degree of the ethylene-modified polyvinyl alcohol is preferably 80 mol% or more, more preferably 90 mol% or more, and still more preferably 95 mol% or more. When the degree of saponification is 80 mol% or more, the water solubility increases and the film formability improves.

(Ethylene-modified polyvinyl alcohol layer)
When a film of ethylene-modified polyvinyl alcohol that is firmly adhered to a paper base is formed, the amount of water vapor permeated can be appropriately controlled to suppress variations in the amount of water vapor permeated. As a result, the foamed state of the thermoplastic resin layer can be made uniform, and the heat insulation can be improved.

  Further, as will be described later, polyethylene is often used as the thermoplastic resin that becomes the foamed resin layer. By the presence of the ethylene-modified polyvinyl alcohol layer on the surface of the paper base material, the polyethylene laminated in the subsequent step adheres firmly to the paper base material. As a result, the permeation amount of water vapor from the paper substrate during foaming becomes even more uniform, overfoaming is suppressed, and the foamed form becomes uniform.

  The ethylene-modified polyvinyl alcohol layer is a layer containing ethylene-modified polyvinyl alcohol as a main component, but may optionally contain other resin components as long as the effects of the invention are not hindered.

  A method for forming the ethylene-modified polyvinyl alcohol layer is not particularly limited. Various known methods such as a coating method, a transfer method, an impregnation method, and a jetting method can be used. The ethylene-modified polyvinyl alcohol layer can be formed, for example, by applying or impregnating a coating liquid containing ethylene-modified polyvinyl alcohol on at least one surface of a paper base material and drying it.

  For the coating liquid, surfactants, antifoaming agents, dyes, pigments, sizing agents, water resistance agents, paper strength enhancers, dispersants, plasticizers, pH adjusters, antifoaming agents, water retention agents are used as necessary. Various known auxiliaries such as additives, preservatives, colored dyes, colored pigments, UV inhibitors may be used in combination.

  The apparatus for applying or impregnating the coating liquid to the paper substrate is not particularly limited, and generally known apparatuses can be used. Examples of the application or impregnation apparatus include a bar coater, a blade coater, an air knife coater, a roll coater, a reverse roll coater, a curtain coater, a slot die coater, a gravure coater, a champlex coater, a brush coater, a slide bead coater, and a calendar size. Examples thereof include a size press coater of a press, two-roll or metering blade system, a bill blade coater, a short dwell coater, a gate roll coater, and a nip coater using a calendar.

Formation of ethylene-modified polyvinyl alcohol layer is a solid per side of the paper substrate component is preferably in the range of 0.2~4.0g / ^{m 2,} the range of 0.3 to 2.0 g / ^{m 2} It is more preferable that it is in the range of 0.4 to 2.0 g / m ² . By forming the amount to be 0.2 g / m ² or more, the film formability and adhesion can be enhanced, and as a result, the heat insulation can be further enhanced. On the other hand, when the coating amount is 4.0 g / m ² or less, it is possible to reduce equipment stains in the paper making process or the drying process when applying the coating liquid, and the dirt falls off and becomes a foreign matter in the foam insulated paper container. Can be prevented. The ethylene-modified polyvinyl alcohol layer is provided on at least one side of the paper substrate, but can also be provided on both sides.

  The method of drying the coating layer after applying the coating solution is not particularly limited, and may be appropriately selected from methods used in known papermaking processes or drying processes. Moreover, after forming an ethylene modified polyvinyl alcohol layer, a smoothing process can be performed as needed. The smoothing process is performed on-machine or off-machine using a smoothing processing apparatus such as a normal super calendar, gloss calendar, or soft calendar.

[Paper base]
(pulp)
In this embodiment, the kind of pulp which comprises a paper base material is not specifically limited. Examples of pulp types include bleached kraft pulp (NBKP) for softwood, bleached kraft pulp (LBKP) for hardwood, groundwood pulp (GP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), desorption. Natural pulp such as wood pulp such as black pulp (DIP), non-wood pulp such as bast pulp, linter pulp, hemp pulp and the like. These pulps can be used singly or in combination of two or more. Especially, it is preferable to use wood pulp from the surface of quality or cost.

  The freeness (Canadian standard freeness, C.S.F.) measured according to JIS P 8121-2012 of the pulp constituting the paper base is preferably adjusted to 300 to 600 ml. The freeness of the pulp may be adjusted to the above range by beating at least one kind of pulp. When two or more kinds of pulp are used, the pulp beaten separately may be mixed to the above range, or the previously mixed pulp may be beaten and adjusted to the above range. When the freeness of the pulp is less than 300 ml, dehydration in the paper making process is slow and the operability may be inferior. On the other hand, if the freeness of the pulp exceeds 600 ml, the paper strength may decrease. The freeness of the pulp is more preferably 300 to 450 ml.

(Paper making)
Paper base paper making method and paper machine type are not particularly limited, such as long paper machine, twin wire paper machine, circular paper machine, gap former, hybrid former (on-top former), etc. The known papermaking method and papermaking machine can be selected.
The pH during papermaking may be any of acidic region (acidic papermaking), pseudo-neutral region (pseudo-neutral papermaking), neutral region (neutral papermaking) and alkaline region (alkaline papermaking). Thereafter, an alkaline agent may be applied to the surface of the paper substrate.

(Filler)
The filler compounded when making the paper substrate is not particularly limited, and any filler generally used in the papermaking field can be used. Examples of fillers include clay, calcined kaolin, delaminated kaolin, heavy calcium carbonate, light calcium carbonate, light calcium carbonate-silica composite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous Examples thereof include inorganic fillers such as silica, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide, and organic fillers such as urea-formalin resin, polystyrene resin, phenol resin, and fine hollow particles. These fillers can be used alone or in combination of two or more. In general, the above-mentioned acidic papermaking is obtained by removing acid-soluble ones from these fillers.

  When making a paper substrate, it is possible to use no filler. When the filler for the paper base material is not blended, the foamability is improved when the thermoplastic resin layer is foamed by moisture contained in the paper base material. On the other hand, when a filler is blended in the paper base material, the opacity of the heat insulating paper container sheet obtained and the foamed heat insulating paper container using the same is improved.

(Internal assistant)
When making a paper substrate, various internal additives can be appropriately selected and used as necessary. Examples of internal additives include various internal sizing agents such as rosin, alkyl ketene dimer (AKD), and alkenyl succinic anhydride (ASA), nonionic, cationic and amphoteric various yield improvers, filtered water Strength improver, paper strength improver, various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide, polyamine resin, polyamine, polyethyleneimine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, hydrophilic Basic polymer compounds such as sulfuric acid band, aluminum chloride, sodium aluminate, basic aluminum chloride, basic polyaluminum hydroxide, water-degradable alumina sol Water-soluble aluminum compounds such as sulfuric acid Monoferric, polyvalent metal compounds such as ferric sulfate, silica sol, defoamers, coloring dyes, coloring pigments, fluorescent brightening agents, pH adjusting agents, pitch control agents, slime control agents.

(Surface pH)
The pH of the paper substrate surface is preferably 6 or less. If the pH of the paper substrate surface is on the acidic side of 6 or less, water is likely to be released from the pulp, and it is considered that the foamability of the thermoplastic resin is improved. The paper pH is measured according to JAPAN TAPPI No.49-2 (coating method).

[Foam insulation paper container base material]
As described above, the foam insulated paper container paper substrate of the present embodiment has an ethylene-modified polyvinyl alcohol layer on at least one surface of the paper substrate, and has the characteristics described below.

(Air permeability resistance)
It is preferable that the air permeation resistance (air permeation resistance / basis weight) per basis weight of the foam insulated paper container paper base is 0.3 to 2.0 s / g / m ² . When the air permeation resistance per basis weight is within this range, in the obtained foam insulation paper container sheet and the foam insulation paper container using the same, the permeation amount of water vapor is moderately suppressed, and the thermoplastic resin layer Since the foamed state is uniform, the balance between heat insulation and beauty is good. The air resistance per basis weight is more preferably 0.5 to 1.9 s / g / m ² , still more preferably 0.8 to 1.8 s / g / m ² , and particularly preferably 1.3 to 1. 0.8 s / g / m ² . The air resistance is measured according to the Oken type testing machine method described in JIS P8117; 2009.

(amount of water)
The moisture content of the foam insulated paper container paper substrate is the sum of the moisture content contained in the paper substrate and the moisture content contained in the ethylene-modified polyvinyl alcohol layer. The amount of water contained in the paper substrate is determined by the basis weight and moisture content of the paper substrate. The moisture content of the foam insulated paper container paper base is preferably 5 to 60 g / m ² , more preferably 10 to 40 g / m ² , and still more preferably 15 to 40 g / m ² . The moisture content is measured according to JIS P8127; 2010 after humidity control.

(Basis weight)
The basis weight of the foam insulated paper container paper base is preferably 100 to 400 g / m ² , more preferably 200 to 400 g / m ² , and still more preferably 220 to 400 g / m ² . When the basis weight is less than 100 g / m ² , foaming tends to be insufficient due to the moisture content, and heat is easily felt when the obtained foam insulated paper container is gripped by hand. On the other hand, when the basis weight exceeds 400 g / m ² , the suitability for molding of the foam heat insulating paper container tends to be lowered.

(density)
The density of the foam insulating paper container paper base material may be appropriately set as desired, and is not particularly limited, but is preferably 0.60 to 0.99 g / cm ³ . When the density of the foam heat insulating paper container paper base is low, water vapor tends to pass through the paper base when foaming the thermoplastic resin layer, and a tendency to improve foamability is observed. However, if the density of the foam insulated paper container paper substrate is less than 0.60 g / cm ³ , the paper strength required for the foam insulated paper container may not be obtained. On the other hand, when the density of the foam heat insulating paper container paper base exceeds 0.99 g / cm ³ , when foaming the thermoplastic resin layer, it becomes difficult for water vapor to pass through the paper base and the foamability tends to decrease.

[Sheet for foam insulation paper container]
As described above, the foam insulated paper container sheet of the present embodiment has a thermoplastic resin layer on at least one surface of a paper base material, and an ethylene-modified polyvinyl alcohol layer between the paper base material and the thermoplastic resin layer. have. It is formed by providing a thermoplastic resin layer on the surface on which the ethylene-modified polyvinyl alcohol layer of the foam heat-insulating paper container paper substrate is formed. By heat-treating the foam insulation paper container sheet, moisture contained in the paper base material and the ethylene-modified polyvinyl alcohol layer is heated and evaporated, and the thermoplastic resin layer becomes a foamed resin layer by the generated water vapor.

(Thermoplastic resin layer)
The thermoplastic resin used for the thermoplastic resin layer is not particularly limited as long as it can be formed on the ethylene-modified polyvinyl alcohol layer and can be foamed. Either heat of crystalline resin or amorphous resin can be used. Plastic resins can also be used.

  Examples of the crystalline resin include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene, polyester resins, polyamide resins, polyacetal resins, and PPS resins. Examples of the amorphous resin include polystyrene, polyvinyl chloride, ABS resin, acrylic resin, modified PPE, polycarbonate, polyurethane, polyvinyl acetate, and amorphous polyethylene terephthalate (PET). As these thermoplastic resins, a single resin may be used in a single layer, a plurality of resins may be mixed, or a plurality of resins may be used.

Among the above thermoplastic resins, polyethylene is preferable because of excellent extrusion lamination properties and foamability. Polyethylene is largely linear low density polyethylene (density: 910-930 kg / m ³ , melting point: 102 ° C.-122 ° C.), low density polyethylene (density: 910-930 kg / m ³ , melting point: 102 ° C.-122 ° C. ), Medium density polyethylene (density: 930 to 942 kg / m ³ , melting point: 110 to 133 ° C.), high density polyethylene (density: 942 to 970 kg / m ³ , melting point: 127 to 135 ° C.). Among these, low density polyethylene is preferable because it is particularly excellent in extrusion laminating properties and foamability.

  The thickness of the thermoplastic resin layer is not particularly limited as long as a foam insulated paper container having desired heat insulation properties can be obtained. From the viewpoint of heat insulation properties and workability, the thickness before foaming is 30 to 80 μm. Is preferred.

(High melting point thermoplastic resin layer, metal layer)
The sheet for the foam insulated paper container of the present embodiment is a high melting point thermoplastic resin layer or aluminum foil having a higher melting point than the thermoplastic resin layer on the surface opposite to the surface on which the thermoplastic resin layer of the paper substrate is formed. A metal layer such as the above may be laminated. When having such a high melting point thermoplastic resin layer or metal layer, when the foamed thermal insulation paper container sheet is heated to foam the thermoplastic resin layer, it is opposite to the surface on which the thermoplastic resin layer of the paper substrate is formed. Water vapor is prevented from evaporating from the side surface, and the foamability of the thermoplastic resin layer is improved.

  At this time, the melting point of the thermoplastic resin used for the high-melting point thermoplastic resin layer is not particularly limited as long as it does not melt at the heating temperature when the water contained in the paper substrate is evaporated by heating and can prevent the diffusion of water vapor. Although it is not, it is preferable that it is 125 degreeC or more. Moreover, in order to form a metal layer on the surface of a paper base material, you may laminate | stack metal foil and may form a metal layer by vapor phase methods, such as a vapor deposition method.

  Furthermore, if a high-melting-point thermoplastic resin layer or metal layer is present on the inner wall surface of at least one of the body member and bottom plate member of the foam insulated paper container, it prevents the liquid filled in the container from penetrating into the paper substrate. This is preferable because it is possible.

  Moreover, you may laminate | stack a high melting point thermoplastic resin layer on the thermoplastic resin layer of the sheet | seat for foam heat insulation paper containers. When a high-melting point thermoplastic resin layer is laminated on the thermoplastic resin layer, water vapor evaporates through the thermoplastic resin layer when the foamed thermal insulation paper container sheet is heated to foam the thermoplastic resin layer. Is suppressed, and foamability is improved.

  When the thermoplastic resin layer is present on the outer wall surface side of the body member of the foam heat insulating paper container, the surface is generally not smooth because irregularities due to foaming occur. When a high-melting point thermoplastic resin layer is laminated on the thermoplastic resin layer, the body surface of the foam heat insulating paper container can be smoothed, so that a foam heat insulating paper container particularly excellent in beauty can be obtained.

  The thermoplastic resin used for the high melting point thermoplastic resin layer may be the same type as the thermoplastic resin used for the thermoplastic resin layer, or may be a different type. For example, when polyethylene is selected for both the thermoplastic resin used for the thermoplastic resin layer and the thermoplastic resin used for the high melting point thermoplastic resin layer, the thermoplastic resin layer is made of low density polyethylene and the high melting point thermoplastic resin layer. By selecting medium density polyethylene or high density polyethylene, it becomes possible to make the melting point of the high melting point thermoplastic resin layer higher than that of the thermoplastic resin layer.

  The difference in melting point between the thermoplastic resin layer and the high melting point thermoplastic resin layer, that is, the difference in melting point between the thermoplastic resin used for the thermoplastic resin layer and the thermoplastic resin used for the high melting point thermoplastic resin layer is 5 ° C. or more. It is preferable. When a plurality of types of resins are laminated in the thermoplastic resin layer or the high-melting point thermoplastic resin layer, the resin having the highest melting point among the resins used for the thermoplastic resin layer and the high-melting point thermoplastic resin layer For the resin having the lowest melting point among the resins used in the above, it is preferable that the difference in melting point is 5 ° C. or more.

  The thickness of the high-melting-point thermoplastic resin layer is such that water vapor is prevented from evaporating from the surface opposite to the surface on which the thermoplastic resin layer of the paper substrate is laminated, or water vapor evaporates through the thermoplastic resin layer. Although what is necessary is just to be able to suppress, and it is not specifically limited, It is about 20-50 micrometers. In particular, when the high melting point thermoplastic resin layer is present on the inner wall surface side of at least one of the body member and the bottom plate member of the foam insulated paper container, the container is filled when the thickness of the high melting point thermoplastic resin layer is 20 μm or more. It is possible to effectively suppress the permeated liquid or the like from penetrating into the paper substrate.

[Method for forming thermoplastic resin layer]
The formation method of the thermoplastic resin layer and the high-melting point thermoplastic resin layer is not particularly limited, and may be laminated on the paper substrate by appropriately using various methods such as an extrusion lamination method, a wet lamination method, and a dry lamination method. The extrusion laminating method is a method in which a thermoplastic resin is extruded from the T die in the state of a molten resin film onto the surface of a paper base, and is pressed and pressure-bonded while being cooled between a cooling roll and a nip roll facing the thermoplastic roll. . Since the adhesion between the paper substrate and the thermoplastic resin layer and the foamability of the thermoplastic resin layer are improved, the extrusion laminating method is preferable.

  The operating conditions of the extrusion laminating method, that is, the melting temperature of the thermoplastic resin, the lamination speed, and the like may be set as appropriate depending on the type and apparatus of the thermoplastic resin to be used, and are not particularly limited. Generally, the melting temperature is about 200 to 370 ° C., and the lamination speed is about 30 to 200 m / min.

  When a high melting point thermoplastic resin layer is laminated on the thermoplastic resin layer, or when the thermoplastic resin layer is formed of a plurality of thermoplastic resin layers, a plurality of thermoplastic resin layers are laminated. When laminating a plurality of thermoplastic resin layers, a so-called co-extrusion laminating method is preferable from the viewpoints of adhesion between the thermoplastic resin layers and production efficiency. The co-extrusion laminating method is a method in which a plurality of extruders are used to guide each thermoplastic resin to a respective T die in a molten state, and the thermoplastic resins are simultaneously extruded from each T die and laminated.

  Furthermore, in order to improve the adhesiveness between the thermoplastic resin layers, an adhesive resin layer may be sandwiched between the thermoplastic resin layers. Moreover, in order to improve the adhesiveness between the paper base material and the thermoplastic resin layer, the paper base material may be previously subjected to corona discharge treatment, ozone treatment, or the like.

[Molding of foam insulation paper container]
The method of forming the foam insulation paper container using the foam insulation paper container sheet is not particularly limited, and can be produced using a known method. As a specific example, there is a method of molding by a general cup molding machine described below.

  First, after printing necessary for a body member blank such as various patterns and barcodes is performed on a predetermined portion of the foam insulation paper container sheet, the body member blank is punched into a predetermined shape. The printed part can be positioned by a conventional method.

  Next, a bottom plate member blank is prepared separately from the body member blank. The bottom plate member blank can be manufactured by punching out a sheet for foamed heat-insulated paper container in the same manner as the body member blank. Moreover, in order to prevent the liquid etc. with which the container was filled from osmose | permeating into a paper base material, it can also be set as the structure different from the sheet | seat for foam heat insulation paper containers of this embodiment. As a sheet | seat used for a baseplate member blank, the sheet | seat coat | covered with the sheet | seat which laminated | stacked the thermoplastic resin on the paper base material, aluminum foil, etc. can be used, for example.

  The thermoplastic resin used for the bottom plate member blank may be the same type of resin as the thermoplastic resin used for the body member blank, or may be a different resin. If the same kind of resin is used as both thermoplastic resins, or if both are made from the same sheet for foam insulated paper container, the body member and the bottom plate member foam at the same time. Even better. In particular, when using a foam insulated paper container outdoors, in the winter, in a cold region, or when using a foam insulated paper container for something that is allowed to stand for a while after pouring hot water, such as cup noodles, It is valid.

  Next, the body member blank and the bottom plate member blank are assembled into a container shape by a cup molding machine. When assembling the body member blank and the bottom plate member blank into a cup shape by a cup molding machine, the thermoplastic resin layer only needs to be present on the outer side and / or the inner side of the body member, and the desired heat insulation. Depending on aesthetics, touch, etc., it may be determined as appropriate.

[Foaming by heat treatment]
In this embodiment, the body member blank and the bottom plate member blank are assembled into a container shape, and then heat treatment is performed. When the heat treatment is performed, moisture contained in the paper base material of the body member blank and the bottom plate member blank is vaporized, and the thermoplastic resin layer is foamed by the generated water vapor to form a foam heat insulating paper container. The foam insulation paper container uses foam insulation paper for at least one of the trunk member and the bottom plate member, and the foam insulation paper has a foam resin layer made of a thermoplastic resin on at least one side of the paper base.

  The heat treatment conditions (heating temperature, heating time) may be appropriately set according to the types of the paper base material and the thermoplastic resin, and are not particularly limited. The heating temperature is preferably slightly higher than the melting point of the thermoplastic resin (melting point + 5 ° C. to melting point + 10 ° C.), and more preferably lower than the melting point of the thermoplastic resin used for the high melting point thermoplastic resin layer. Generally, the heating temperature is about 100 to 200 ° C., and the heating time is about 1 to 6 minutes.

  Arbitrary means such as hot air, electric heat, or electron beam can be used for the heat treatment. If the heat treatment is continuously performed in a tunnel provided with a conveyor means, a foamed insulated paper container can be manufactured at low cost and with high productivity.

  In the foam insulation paper container of this embodiment, a technique well-known in the field of a paper container can be applied as needed in the range which does not impair a desired effect. For example, a technique (Patent No. 3014629) for partially suppressing foaming by applying a paint containing 5 to 40 wt% of a synthetic resin component on a part of the outer side of the body member, and the foamed heat insulating paper A technology (Patent No. 3408156) for applying a synchronized ink that forms a smooth printing surface in synchronization with foaming on the outer wall surface of the container, and an upper flange portion forcedly processed into a square cross section is provided at the upper edge of the opening of the barrel member A technique of superposing the inner winding end on the upper part of the flange portion to form a double structure (Japanese Patent Laid-Open No. 2001-354226), etc., is not limited thereto. Further, in order to enhance the beauty, an ink receiving layer mainly composed of a pigment and a binder may be provided on the outermost layer of the body member serving as the outer wall surface of the foam insulated paper container.

  Moreover, about the cover material used for a foam heat insulation paper container, what punched the sheet | seat for foam heat insulation paper containers can be used similarly to the said baseplate member blank. Moreover, in order to prevent the liquid etc. with which the container was filled from osmose | permeating into a paper base material, it can also be set as the structure different from the sheet | seat for foam heat insulation paper containers of this embodiment. As a sheet used for the lid member, for example, a sheet obtained by laminating a thermoplastic resin on a paper substrate, a sheet coated with an aluminum foil, or the like can be used.

  The foam insulation paper container of this embodiment is a foam insulation paper container for filling hot coffee used for vending machines and the like, a foam insulation paper container for instant food for injecting hot water, and a container for cooking by a microwave oven Can be used as etc.

  Hereinafter, the effects of the present invention will be described in detail by way of examples. Unless otherwise specified, “parts” and “%” represent “parts by mass” and “mass%”, respectively. The Canadian standard freeness (C.S.F.) of the pulp was measured according to JIS P8121.

[Example 1]
(Foam insulation paper container paper base)
Hardwood bleached kraft pulp LBKP (C.S.F.380 ml) was used as the pulp, and a paper slurry containing 2 parts of aluminum sulfate and 0.35 part of rosin sizing agent was added to 100 parts of pulp raw material in terms of solid content. Paper was made with a long net paper machine to obtain a paper substrate (base paper). Next, on both sides of the obtained paper base material (base paper), ethylene-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., product name: HR-3010, saponification degree 99.0 to 99.4%) is solidified on one side by a calendar size press. It was coated and dried so as to be 0.5 g / m ² per minute (1.0 g / m ^{2 on} both sides), and the foam insulated paper container paper base material of Example 1 was obtained. Foam insulation paper containers paper substrate of Example 1 had a basis weight 300 g / ^{m 2,} a density 0.90 g / cm ^3, water content 22.5 g / ^{m 2,} air resistance per basis weight 1.43s / g / M ² .

(Sheet for foam insulation paper container)
A thermoplastic resin (medium density polyethylene, density 940 kg / m ³ , melting point 133 ° C.) having a melting point of 360 ° C., lamination speed is applied to one surface of the foam insulation paper container paper base material so as to have a thickness of 40 μm. Extrusion was performed at 50 m / min. Then, using a cooling roll and a nip roll (JIS-A hardness: 70), it pressed and pressure-bonded by the linear pressure of 2 kgf / cm, and formed the high melting-point thermoplastic resin layer.

Next, a thermoplastic resin (low density polyethylene, density 918 kg / m ³ , melting point 103 ° C.) is melted at a melting temperature of 360 ° C. and a lamination speed of 50 m / cm on the other surface of the foam insulating paper container paper base so as to have a thickness of 50 μm. Extruded in minutes. Then, using a cooling roll and a nip roll (JIS-A hardness: 70), it presses and crimps | bonds by linear pressure 2kgf / cm, forms a thermoplastic resin layer, and obtains the sheet | seat for foam insulation paper containers of Example 1 It was.

[Example 2]
In the foam insulated paper container base material of Example 2, the amount of the ethylene-modified polyvinyl alcohol layer formed was 1.8 g / m ^{2 in} terms of solid content per side. The rest is the same as in the first embodiment. Foam insulation paper containers paper substrate of Example 2 had a basis weight 300 g / ^{m 2,} a density 0.89 g / cm ^3, water content 23.4 g / ^{m 2,} air resistance per basis weight 1.94s / g / M ² . Thereafter, a high-melting point thermoplastic resin layer and a thermoplastic resin layer were formed in the same manner as in Example 1 to obtain a foam insulated paper container sheet of Example 2.

[Example 3]
In the foam insulated paper container base material of Example 3, the amount of ethylene-modified polyvinyl alcohol layer formed was 0.3 g / m ^{2 in} terms of solid content on one side, and the calendar size press was a two-roll size press. The rest is the same as in the first embodiment. Foam insulation paper containers paper substrate of Example 3 had a basis weight 300 g / ^{m 2,} a density 0.89 g / cm ^3, water content 23.4 g / ^{m 2,} air resistance per basis weight 0.93s / g / M ² . Thereafter, a high-melting point thermoplastic resin layer and a thermoplastic resin layer were formed in the same manner as in Example 1 to obtain a foam insulated paper container sheet of Example 3.

[Example 4]
In the foam insulated paper container paper base of Example 4, the grade of ethylene-modified polyvinyl alcohol was changed to Kuraray RS2117 (saponification degree: 97.5-99.0%), and the amount of ethylene-modified polyvinyl alcohol layer formed on one side was changed. The solid content was 0.6 g / m ² . Other than that is the same as Example 3. Foam insulation paper containers paper substrate of Example 4 had a basis weight 300 g / ^{m 2,} a density 0.90 g / cm ^3, water content 21.1 g / ^{m 2,} air resistance per basis weight 1.33s / g / M ² . Thereafter, a high-melting point thermoplastic resin layer and a thermoplastic resin layer were formed in the same manner as in Example 1 to obtain a foam insulated paper container sheet of Example 4.

[Example 5]
In the foam insulated paper container paper base of Example 5, the grade of ethylene-modified polyvinyl alcohol was changed to Kuraray RS2817 (saponification degree: 95.5-97.5%), and the amount of ethylene-modified polyvinyl alcohol layer formed on one side was changed. The solid content was 0.46 g / m ² . The rest is the same as in the first embodiment. The foam insulated paper container of Example 5 has a basis weight of 300 g / m ² , a density of 0.91 g / cm ³ , a moisture content of 21.5 g / m ² , and an air resistance per basis weight of 1.50 s / g. / M ² . Then, the high melting point thermoplastic resin layer and the thermoplastic resin layer were formed in the same manner as in Example 1 to obtain the foam insulated paper container sheet of Example 5.

[Comparative Example 1]
In the foam insulated paper container base material of Comparative Example 1, ethylene-modified polyvinyl alcohol was changed to unmodified polyvinyl alcohol (fully saponified polyvinyl alcohol, product name: PVA117), and the amount of unmodified polyvinyl alcohol layer formed The solid content per side was 1.0 g / m ² . The rest is the same as in the first embodiment. Foam insulation paper containers paper substrate of Comparative Example 1 had a basis weight 300 g / ^{m 2,} a density 0.90 g / cm ^3, water content 22.3 g / ^{m 2,} air resistance per basis weight 0.70s / g / M ² . Thereafter, a high-melting point thermoplastic resin layer and a thermoplastic resin layer were formed in the same manner as in Example 1 to obtain a foam insulated paper container sheet of Comparative Example 1.

[Comparative Example 2]
In the foam insulation paper container base material of Comparative Example 2, the ethylene-modified polyvinyl alcohol was changed to starch (hydrophobized starch, manufactured by Oji Cornstarch, GRS-T110), and the amount of starch layer formed was 1.0 g in solid content per side. / M ² . The rest is the same as in the first embodiment. The foam base material of Comparative Example 2 has a basis weight of 300 g / m ² , a density of 0.90 g / cm ³ , a moisture content of 25.6 g / m ² , and an air resistance per basis weight of 0.11 s / g. / M ² . Thereafter, a high-melting point thermoplastic resin layer and a thermoplastic resin layer were formed in the same manner as in Example 1 to obtain a foam insulated paper container sheet of Comparative Example 2.

The following evaluation was performed about the sheet | seat for foam heat insulation paper containers obtained by making it above. The evaluation results are shown in Table 1.
(Adhesion)
The adhesion between the foam insulating paper container paper base and the thermoplastic resin layer when the thermoplastic resin layer was simply formed in the laboratory was visually evaluated. The lamination conditions in the laboratory are as follows. The thickness of the thermoplastic resin layer was 50 μm, the melting temperature during lamination was 350 ° C., and the lamination speed was 6 m / min.
A: Adhering sufficiently.
○: Adhering.
(Triangle | delta): There exists a location with inadequate contact.

(Thermal insulation properties)
An A4 size sample was cut out from the obtained foam insulation paper container sheet. A cylinder was created with the thermoplastic resin layer on the outside. Thereafter, using a hot air, the thermoplastic resin layer outside the cylinder was foamed at a heating temperature of 120 ° C. and a heating time of 6 minutes.
The foaming ratio was calculated from the thickness before and after foaming of the obtained foam insulation paper, and evaluated according to the following criteria.
A: The expansion ratio is 21 times or more, and the heat insulation is sufficient.
○: The expansion ratio is 19 times or more and less than 21 times, and the heat insulation is sufficient.
Δ: Foaming ratio is 15 times or more and less than 19 times, and there is heat insulation.
X: The expansion ratio is less than 15 times, and the heat insulation is insufficient.

(Beautiful)
A square test piece having a side of 100 mm was cut out from the obtained sheet for foam insulated paper container. Thereafter, the hot air was used to foam the thermoplastic resin layer at a heating temperature of 120 ° C. and a heating time of 6 minutes. The surface of the thermoplastic resin layer after foaming was visually observed, and the beauty was evaluated according to the following criteria.
A: No excessive foaming is observed, the formed foam cells are small and homogeneous, and the surface is generally flat.
◯: No excessive foaming was observed, and the formed foamed cells were small and the surface was generally flat, but there was variation in the size of the foamed cells.
(Triangle | delta): Although the formed foaming cell is a little large and a size variation is seen, the unevenness | corrugation of the surface is small and overfoaming is not seen.
X: There are large irregularities on the surface such as excessive foaming.

  As can be seen from Table 1, the foamed insulated paper container sheets of Examples 1 to 5 were excellent in any of adhesion, heat insulation, and beauty. In addition, in Table 1, although the relative magnitude | size of the ethylene modification degree of ethylene modification polyvinyl alcohol was shown, the direction using polyvinyl alcohol with a high degree of ethylene modification was excellent in beauty. The sheet for the foam insulated paper container of Comparative Example 1 has an unmodified polyvinyl alcohol layer formed on the surface of the paper base material, but the permeation resistance per basis weight is slightly low, so the amount of water vapor permeated There were variations depending on the location of the foamed resin layer, and the foamed resin layer had poor foaming uniformity. Therefore, the foam insulation paper container sheet of Comparative Example 1 was slightly inferior in heat insulation and inferior in beauty. The sheet for the foam insulated paper container of Comparative Example 2 has a starch layer formed on the surface of the paper substrate, but the air resistance per basis weight is considerably small, and the amount of water vapor permeated is low. Due to variations in location, the foamed resin layer had poor foam uniformity, and was poor in heat insulation and beauty. Moreover, the sheet | seat for foam heat insulation paper containers of the comparative example 2 was also somewhat inferior to the adhesiveness of a foam heat insulation paper container paper base material and a thermoplastic resin layer.

DESCRIPTION OF SYMBOLS 1 Paper base material 2 Ethylene modified polyvinyl alcohol layer 3 Foam heat insulation paper container paper base material 4 Thermoplastic resin layer 5 Sheet for foam heat insulation paper container 6 Body member 7 Bottom plate member 8 Foam heat insulation paper container 9 Foam resin layer 10 High melting point thermoplasticity Resin layer

Claims (9)

  A foam base paper container having an ethylene-modified polyvinyl alcohol layer on at least one side of a paper base. The air-permeable resistance per basis weight is 0.3 to 2.0 s / g / m ² , The foam insulated paper container paper base material according to claim 1. The foam-insulated paper container paper base according to claim 1 or ² , wherein the amount of the ethylene-modified polyvinyl alcohol layer formed is 0.2 to 4.0 g / m ^{2 on} one side. The foam insulating paper container paper base according to any one of claims 1 to ³ , wherein the density is 0.60 to 0.99 g / m ³ . The moisture insulating paper container base material according to claim 1, wherein the moisture content is 5 to 60 g / m ² . A sheet for a foam insulated paper container having a thermoplastic resin layer on at least one side of a paper substrate,
A foam insulated paper container sheet comprising an ethylene-modified polyvinyl alcohol layer between the paper substrate and the thermoplastic resin layer.   The foamed insulated paper container sheet according to claim 6, wherein the thermoplastic resin layer has a thickness of 30 to 80 µm.   The sheet for a foam insulated paper container according to claim 6 or 7, wherein the thermoplastic resin is polyethylene. A foam insulation paper container using foam insulation paper for at least one of the body member and the bottom plate member,
The foam insulation paper has a foamed resin layer made of a thermoplastic resin on at least one side of a paper substrate,
A foam insulated paper container having an ethylene-modified polyvinyl alcohol layer between the paper substrate and the foamed resin layer.

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