JP2019108627A - Paper base material for foamed heat-insulating paper container, sheet for foamed heat-insulating paper container, and heat-insulating paper container - Google Patents

Abstract

To provide a paper base material for a foamed heat-insulating paper container which facilitates formation of a top curl part by achieving both such a tensile force as to withstand a tensile force at the time of top curl processing and easy curling-up, and a sheet for a foamed heat-insulating paper container and a heat-insulating paper container using the same.SOLUTION: A paper base material for a foamed heat-insulating paper container includes a paper base material containing cellulose pulp as a main component and a water-soluble resin layer provided on at least one surface of the paper base material, in which a Z-axis strength is 380-560 kN/m, a tensile strength in an MD direction is 15.0-35.0 kN/m, and Taber stiffness in the MD direction measured according to the Taber stiffness test machine method defined by JIS P8125:2000 is 17.0 mN m or less.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a foam insulation paper container and a foam insulation paper container sheet base used for the production thereof and a sheet for the foam insulation paper container.

  2. Description of the Related Art In fast food stores, trains, vending machines, etc., heat insulating containers are widely used as cup-shaped containers or the like for providing buyers with warm beverages such as coffee and warm foods such as soup.

As a sheet which forms the heat insulation container of such a use, there exists invention disclosed by patent document 1, for example. This is a sheet for a foam insulation paper container in which a thermoplastic resin layer such as polyethylene is laminated on at least one side of a foam insulation paper container paper base, and the foam insulation insulation paper in which the surface of the paper base is treated by a calender size press It is an invention concerning a sheet for containers.
A foam insulation paper container can save oil resources as compared to a heat insulation container made of expanded polystyrene (EPS), and has an advantage such as excellent beauty (printability) because the outer surface of the container is smooth. is there.

  The foam insulation paper container is required to have sufficient strength and ease of handling as well as heat insulation. Therefore, in the foam insulation paper container, a portion serving as a mouth (hereinafter referred to as a top curl portion) is formed by top curl processing in which the peripheral edge of the upper end opening is wound outward. In addition to the role of increasing the strength of the foam insulation paper container, the top curl portion also plays a role as a hook when the foam insulation paper container is mechanically supported by an automatic feeder or the like.

A typical automatic feeder for cup-shaped containers uses the top curl portion of the container for automatic feeding. For example, an automatic paper cup feeder in a vending machine stores a large number of paper cups stacked in the vertical direction. The paper cup automatic feeding device supports a large number of paper cups by engaging with the top curl portion of the lowermost paper cup at the time of standby, and immediately after releasing the engagement at the time of sale Engage with the top curl of the paper cup. Thus, the paper cup automatic feeding apparatus securely uses the top curl portion to drop the paper cups one by one and provides them to the user. Such an automatic feeding mechanism is also used for the automatic feeding of foam insulation paper containers.
As described above, since the top curl portion is often provided in the foam insulation paper container, the ease of making the top curl portion may be mentioned as one of the qualities required for the foam insulation paper container paper base. .

  As an example of the method of top curling of a cup-like container, for example, top curling in a paper cup is performed as follows. First, a mold for upper molding of the top curl portion and a mold for lower molding are prepared. Each mold is given a specific curled shape. A mold for upper molding is placed from the paper cup upper end opening side, and the paper cup upper end opening peripheral edge is curled outward. Next, by pushing the paper cup downward, the paper cup upper end opening peripheral edge is wound inward along the curved surface of the lower molding die set downward, and the top curled part is formed.

JP, 2012-214038, A

In the method of top curl processing described above, when forming the top curl portion, a tensile force acts on the outer side of the top curl portion and a compressive force acts on the inner side.
If the tensile force and the compressive force are appropriate, the top curled part can be formed properly. However, if an excessive tensile force acts on the outside of the top curled part, breakage or swelling may occur in the top curled part. On the other hand, if an excessive compressive force acts on the inside of the top curl portion, the top curl portion may be broken or the like. As described above, if an excessive force is applied to the top curled portion at the time of top curling, there is a risk of causing a defect in forming the top curled portion.

In addition, the foam / insulation paper container paper base requires a certain basis weight or paper thickness to secure moisture that causes the foam resin layer to foam. When the basis weight and the thickness of the paper are increased, the rigidity of the foam insulation paper container paper base becomes larger than that of the paper cup base. Paper with high stiffness is paper that requires a large amount of force to be rolled. Therefore, when top curl processing is applied to the foam insulating and heat-insulating paper container sheet base having a large rigidity, excessive force is likely to act on the top curled portion, so that formation of the top curled portion tends to be defective.
Furthermore, when an excessive tensile force acts on the outside of the top curl portion and an excessive compressive force acts on the inside, a large shear force acts on the paper layer of the foam insulation paper container paper base. Due to this shearing force, the joint portion (seam portion) of the side of the foam insulation paper container of the top curl portion may be pulled off, which may cause a problem that the seam portion may be curled up.

Since the top curl portion plays a role as described above, the foam insulation paper container in which the formation of the top curl portion has a defect does not withstand practical use.
It is conceivable to increase the tensile strength of the foam insulation paper container paper base material as one of the methods of suppressing the problem of molding of the top curl portion. If the tensile strength is high, even if a large tensile force is applied during molding, the foam insulation / heat insulating paper container sheet base is difficult to break, so that the problem of molding of the top curled part hardly occurs.

However, even if the tensile strength of the paper is increased, the problem caused by the curling of the high stiffness paper is not solved.
Furthermore, high tensile strength paper is often high compression strength paper.
Paper having a large compressive strength requires a large force to compress and roll the inside of the top curled portion during top curling, so the top curled portion is likely to be broken or the like. In particular, the bonding portion (seam portion) on the side surface of the foam insulation paper container is doubled with the foam insulation paper container paper base material, and two sheets of paper are overlapped and rolled up, so the top curl processing is the other It will be more difficult than the site. Therefore, if a foam insulation / heat insulation paper container paper base having a large compressive strength is used, the inside of the top curled part may not be properly compressed at the seam part. If the inside of the top curled part is not properly compressed, a problem (curling up of the seamed part) that a part of the top curled part is flipped up tends to occur.
Thus, the foam insulation heat insulating paper container paper base which is hard to round off has been the cause of the problem of deteriorating the yield of the foam insulation heat insulation paper container.

  From the above, there is a demand for a foam insulation paper container paper base material which is easy to form the top curled part and which is excellent in heat insulation and surface aesthetics.

  The present invention has been made in view of such a situation. That is, the subject of the present invention is a foam insulation paper container paper base material which can be easily formed into a top curled portion by making it possible to balance the tensile force enough to withstand the tensile force at the time of top curling and the ease of rounding. It is providing a sheet for foam insulation paper containers used and a foam insulation paper container.

The direction (longitudinal direction) in which the pulp slurry flows out in the process of forming the paper layer in papermaking of the paper base in the foam insulation paper container paper base is hereinafter also referred to as the MD direction.
The inventors of the present invention proceeded with a paper cup base paper having both a tensile strength enough to withstand the tensile force at the time of top curl processing and a rounding tendency. As a result, it has been found that not only the reduction in compressive strength but also the reduction in Z-axis strength (interlayer strength) is effective as a means for achieving roundness.
According to the present discovery, if the Z-axis strength and the tensile strength are within a certain range and the Taber stiffness is sufficiently small, the foam insulation without any breakage in the top curl portion and with sufficient roundness Paper container A paper substrate can be realized.
In particular, in the seam portion, the paper layer inside the top curled portion buckles and deforms following the paper layer outside, so the paper layer inside and at the tip of the seam portion It becomes difficult to produce a crack, exfoliation etc. in the meantime, and it can control turn-off of a seam part by extension.
The present invention has been completed based on such findings. That is, the present invention has the following configuration.

(1) A foam insulation paper container paper base material comprising a paper base material mainly composed of cellulose pulp and a water-soluble resin layer provided on at least one surface of the paper base material, wherein Z in the MD direction MD whose tensile strength in the MD direction is from 380 to 560 kN / m ² , tensile strength in the MD direction is from 15.0 to 35.0 kN / m, and measured according to the Taber stiffness tester defined in JIS P8125: 2000 Foam insulation paper container base material characterized in that the Taber stiffness in the direction is 17.0 mN · m or less.

(2) The foam insulation paper container sheet base material according to (1), wherein the content of softwood kraft pulp with respect to the cellulose pulp is 20% by mass or less.

(3) A foam insulation paper container sheet base material described in the above (1) or (2), characterized in that the disintegration freeness of the cellulose pulp measured in accordance with JIS P 8121: 2012 is 410 to 530 ml.

(4) The foam insulation paper container paper base material according to any one of the above (1) to (3), wherein the water-soluble resin constituting the water-soluble resin layer is polyvinyl alcohol.

(5) A sheet for a foam insulation paper container, characterized in that a thermoplastic resin layer is provided on both sides of the foam insulation paper container sheet base material according to any one of the above (1) to (4).

(6) A foam insulation paper container comprising the sheet for foam insulation paper container according to (5).

  Since the foam insulation paper container paper base material of the present invention has tensile strength and Z-axis strength in a certain range, and rigidity is sufficiently small, it is suitable for forming a top curled part and generation of curling of the seamed part It can be suppressed. The foam insulation sheet container sheet and the foam insulation sheet container of the present invention use the foam insulation sheet container sheet base, so that the top curled portion can be easily formed.

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

  Hereinafter, embodiments of the present invention will be specifically described. The description of the configuration requirements described below may be made based on typical embodiments and specific examples, but the present invention is not limited to such embodiments. In addition, the numerical range represented using "-" in this specification means the range which includes the numerical value described before and after "-" as a lower limit and an upper limit.

  FIG. 1 is a schematic cross-sectional view of a foam insulation paper container 8 according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of a portion indicated by A in FIG. As shown in FIG. 1, in this embodiment, the foam insulation paper container 8 uses foam insulation paper 20 for the body member 6 and the bottom plate member 7. The foam insulation paper 20 may be used for any one of the body member 6 and the bottom plate member 7.

  As shown in FIG. 2, the foamed heat insulating paper 20 has a foamed resin layer 9 made of a thermoplastic resin on at least one side of the paper substrate 1. The foam insulation paper 20 has a water-soluble resin layer 2 between the paper base 1 and the foam resin layer 9. In FIG. 2, the water-soluble resin layer 2 is formed on both sides of the paper substrate 1. Furthermore, the foamed heat insulating paper 20 has the foamed resin layer 9 described above on the outer wall surface side, and has the high melting point thermoplastic resin layer 10 described later on the inner wall surface side.

  FIG. 3 is a schematic cross-sectional view of the foam insulation sheet container sheet 5 according to the present embodiment. The sheet 5 for foam insulation paper container according to the present embodiment is used to manufacture the foam insulation paper 20 described above. The sheet 5 for foam insulation paper container according to the present embodiment has the thermoplastic resin layer 4 on at least one side of the paper base 1 and is water-soluble between the paper base 1 and the thermoplastic resin layer 4. It has a resin layer 2. The thermoplastic resin layer 4 is foamed by heat treatment to form a foamed resin layer 9 (see FIG. 2).

  FIG. 4 is a schematic cross-sectional view of a foam and heat insulating paper container paper base 3 according to the present embodiment. The foam and insulation paper container sheet base 3 according to the present embodiment is used to manufacture the foam and insulation paper container sheet 5 described above. The foam and heat insulating paper container paper base 3 according to the present embodiment has the water-soluble resin layer 2 on at least one side of the paper base 1. By providing the thermoplastic resin layer 4 on the water-soluble resin layer 2, the above-described foam insulation sheet container sheet 5 is formed.

  The foam and heat insulating paper container sheet 5 is used for the body member 6 and the bottom plate member 7 to form a paper container. Thereafter, by heating the paper container, the water contained in the paper base 1 and the water-soluble resin layer 2 is vaporized to be water vapor. The generated water vapor passes through the water-soluble resin layer 2 and penetrates into the heated thermoplastic resin layer 4 to foam the thermoplastic resin, and the thermoplastic resin layer 4 is converted to the foamed resin layer 9. As a result, the paper container becomes a foam insulation paper container 8 having heat insulation.

[Foam insulation paper container paper base material]
The foam insulation paper container paper base 3 has a paper base 1 and a water-soluble resin layer 2 on at least one side thereof. If the water-soluble resin layer 2 is not formed on the surface of the paper substrate 1, water vapor is directly released from the paper substrate 1 when heated. Due to this release, the amount of water vapor permeation becomes uneven depending on the location of the paper substrate 1, and in the foaming of the thermoplastic resin layer 4, there is a tendency that partial foaming tends to occur. When the over-foamed portion is present, the foam form becomes uneven and the surface is roughened, so that both the heat insulating property of the foam and insulation paper container 8 and the beauty of the surface are reduced.
Hereinafter, each member which comprises this embodiment is demonstrated.

(pulp)
Cellulose pulp (pulp) is a main component of the paper base 1 constituting the foam insulation paper container paper base 3. The cellulose pulp is not particularly limited, but it is preferable to contain a chemical pulp from the viewpoint of strength. The chemical pulp is not particularly limited, but it is preferable to contain hardwood kraft pulp (LKP) or softwood kraft pulp (NKP). The pulp may be bleached pulp or unbleached pulp. Furthermore, it is preferable to contain both LKP and NKP. Hereinafter, although LKP and NKP contain bleached pulp or unbleached pulp, respectively, unless otherwise specified, hardwood bleached kraft pulp may be referred to as LBKP, and softwood bleached kraft pulp may be referred to as NBKP.

Here, in the paper base 1, it is preferable to blend NKP at a predetermined ratio in order to increase the tensile strength. Because of the long fibers, NKP can increase the tensile strength of the machined product.
However, when the compounding amount of NKP is increased, not only tensile strength but also compressive strength tends to increase. Therefore, in order to realize the foamed insulation paper container paper base 3 excellent in the balance between the tensile strength and the compressive strength, the content of NKP is 20% by mass or less with respect to the total mass of the pulp component. The content is preferably 15% by mass or less, and more preferably 9% by mass or less.

  LKP is short in fiber and inferior in strength as compared with NKP, but excellent in texture and smoothness of paper made of paper. Since uniform formation of the thermoplastic resin layer 4 requires good texture and smoothness of the paper substrate 1, the content of LKP is 40% by mass or more with respect to the total mass of the pulp component 60 mass% is more preferable, and 80 mass% or more is more preferable.

  The pulp component may contain pulp other than the above NKP and LKP (hereinafter referred to as other pulp). Other pulps include stone ground pulp (SGP), pressed stone ground pulp (PGW), refiner ground pulp (RGP), thermoground pulp (TGP), chemiground pulp (CGP), ground pulp (GP), thermo Manufactured from mechanical pulp (TMP) and other mechanical pulp, waste paper, kraft envelope waste paper, magazine waste paper, newspaper waste paper, flyer waste paper, office waste paper, corrugated waste paper, white waste paper, white waste paper, Kent waste paper, imitation waste paper, ground paper waste paper, etc. Examples thereof include disintegrated paper pulp (DIP), and pulp chemically or mechanically produced from non-wood fibers such as kenaf, hemp, straw and the like. The content of the other pulp is preferably less than 3% by mass, more preferably less than 2% by mass, and still more preferably less than 1% by mass, based on the total mass of the pulp components.

Generally, if the freeness of the pulp component is reduced, the tensile strength of the paper-made product can be increased.
However, if the freeness is reduced, not only tensile strength but also compressive strength tends to increase. In order to realize the foam insulation paper container paper base 3 excellent in the balance between the tensile strength and the compression strength, it is preferable that the disintegration freeness (csf) of the foam insulation paper container paper base 3 is 410 to 530 ml. The disaggregation freeness (csf) is more preferably 420 to 520 ml, further preferably 430 to 510 ml.

In addition, disaggregation freeness (csf) refers to the value of the Canadian standard freeness measured using the pulp slurry obtained by disaggregating the paper base material 1. FIG.
The disaggregation freeness (csf) can be adjusted by increasing or decreasing the freeness of the cellulose pulp before papermaking. The freeness (csf) of the cellulose pulp before paper making is preferably 360 to 480 ml, more preferably 370 to 470 ml, and still more preferably 380 to 460 ml.

(Papermaking)
The paper making method of the paper base 1 and the model of the paper machine are not particularly limited, and a Fourdrinier paper machine, a twin wire paper machine, a cylinder paper machine, a gap former, a hybrid former (on top former) And the like can be selected.
The paper substrate 1 may be composed of a single layer, or may be composed of multi-layered pulping that is made up of a plurality of inlets.
The pH at the time of papermaking may be any of acidic region (acidic paper making), pseudo neutral region (pseudo neutral paper making), neutral region (neutral paper making) and alkaline region (alkaline paper making), and after paper making in acidic region, An alkaline agent may be applied to the surface of the paper substrate 1.

(Filler)
The filler compounded in making the paper substrate 1 may be any filler generally used in the papermaking field, and is not particularly limited. Examples of fillers include clay, calcined kaolin, delaminated kaolin, ground 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 micro hollow particles. These fillers can be used alone or in combination of two or more. In the case of the above-mentioned acidic papermaking, in general, those obtained by removing acid-soluble ones from these fillers are used.

  When papermaking the paper base material 1, it is also possible to make a filler non-blending. When the filler of the paper base 1 is not blended, when the thermoplastic resin layer 4 is foamed by the moisture contained in the paper base 1, the foamability is improved. On the other hand, when the filler is blended in the paper base 1, the opacity of the obtained foam insulation sheet container sheet 5 and the foam insulation sheet container 8 using the sheet is improved.

(Internal auxiliary agent)
When making the paper substrate 1, it is possible to appropriately select and use various internal additives as needed. Examples of internal additives include various internal sizing agents such as rosin, alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA), various nonionic, cationic, amphoteric retention improvers, drainage Degree improver, paper strength improver, various starches such as cationized starch, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide, polyamine resin, polyamine, polyethylene imine, plant gum, polyvinyl alcohol, latex Polyethylene oxide, dispersion of hydrophilic cross-linked polymer particles and derivatives or modified products thereof, sulfuric acid bands, aluminum chloride, sodium aluminate, basic aluminum chloride, basic aluminum compounds such as basic polyaluminum hydroxide, water Water soluble such as easily degradable alumina sol Listed are minium compounds, polyvalent metal compounds such as ferrous sulfate and ferric sulfate, silica sol, antifoaming agents, coloring dyes, coloring pigments, fluorescent whitening agents, pH adjusters, pitch control agents, slime control agents, etc. Be

(Water soluble resin)
The water-soluble resin is applied to the surface of the paper substrate 1 of the present invention to form a film (water-soluble resin layer 2). The water-soluble resin layer 2 has a role to make the foaming of the thermoplastic resin layer 4 uniform and to improve the heat insulation and the surface beauty of the foam insulation paper container 8.
A water soluble resin is a resin that dissolves in water. The water-soluble resin is not particularly limited as long as it is a water-soluble polymer having a film-forming property. As the water-soluble resin, for example, completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, polyvinyl alcohol such as modified polyvinyl alcohol, starches, polyacrylamides, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, acetyl cellulose and the like Cellulose ethers and their derivatives, and the like. These can be used alone or in combination of two or more.

(Polyvinyl alcohol)
As a water-soluble resin which forms the water-soluble resin layer 2 of the present invention, polyvinyl alcohol is preferable from the viewpoint of processability.
Polyvinyl alcohol has the formula _{[-CH 2 CH (OH) -} ] n [-CH 2 CH (OCOCH 3) -] is represented by _m, PVOH or PVA, which is called such as PVA. Polyvinyl alcohol is generally produced by saponifying a polyvinyl acetate resin obtained by polymerizing a vinyl acetate monomer. In the chemical formulae, n represents a saponified portion, and m represents an unsaponified portion.

  As polyvinyl alcohol, partially saponified polyvinyl alcohol or completely saponified polyvinyl alcohol (in this embodiment, those having a degree of saponification of 90 mol% or more) can be used. The average degree of polymerization is represented by n + m, and the degree of saponification (mol%) is represented by {n / (n + m)} × 100. The average degree of polymerization can be optionally adjusted depending on how much vinyl acetate monomer is bonded in the step of polymerizing vinyl acetate monomer. The degree of saponification can be optionally adjusted depending on how much vinyl acetate units are converted to hydroxyl groups in the step of saponifying the polyvinyl acetate resin. The average degree of polymerization and the degree of saponification can be measured according to JIS K6726-1994.

In addition, as polyvinyl alcohol, unmodified polyvinyl alcohol into which no functional group other than hydroxyl group (OH group) and acetic acid group (OCOCH ₃ group) is introduced can be used. Furthermore, as polyvinyl alcohol, the modified polyvinyl alcohol which introduce | transduced functional groups other than a hydroxyl group and an acetic acid group can also be used. As a functional group introduce | transduced into modified polyvinyl alcohol, a carboxyl group, a carbonyl group, a sulfonic acid group, a silanol group, a cation group, an alkyl group etc. are mentioned, for example. That is, as modified polyvinyl alcohol, polyvinyl alcohols, such as carboxyl modified polyvinyl alcohol, silanol modified polyvinyl alcohol, cation modified polyvinyl alcohol, terminal alkyl modified polyvinyl alcohol, etc. are mentioned.

  The reason why polyvinyl alcohol is excellent as a material of the film to be formed on the paper substrate 1 is presumed as follows. Polyvinyl alcohol forms a film firmly adhered on the paper substrate 1 because a hydrophilic functional group (hydroxyl group) and a hydrophobic functional group (acetic acid group) appropriately coexist in the polymer molecule. . The polyvinyl alcohol layer firmly adhered on the paper substrate 1 can appropriately control the permeation amount of water vapor and can suppress the variation of the permeation amount of water vapor. As a result, the foamed state of the thermoplastic resin layer 4 can be made uniform, and the heat insulation of the foam insulation paper container 8 can be improved.

  When the average polymerization degree of polyvinyl alcohol is measured based on JISK6726-1994, 300-4000 are preferable, 500-3000 are more preferable, and 1000-2000 are more preferable. By setting the average degree of polymerization to 300 or more, the film forming property is improved. Further, by setting the average degree of polymerization to 4000 or less, the solubility in water is improved, the solution viscosity is reduced, and the coating becomes easy.

  The degree of saponification of the 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 is increased and the film forming property is improved. Polyvinyl alcohol can be suitably selected and used from what is marketed.

(Starch)
As a water-soluble resin, it is also possible to use starches in addition to polyvinyl alcohol.
Examples of starches include unmodified starch, enzyme-modified starch, thermochemically modified starch, oxidized starch, esterified starch, etherified starch (for example, hydroxyethylated starch and the like), cationized starch and the like.

(Polyacrylamides)
As a water-soluble resin, it is also possible to use polyacrylamides in addition to polyvinyl alcohol.
The polyacrylamides include polyacrylamides, cationic polyacrylamides, anionic polyacrylamides, amphoteric polyacrylamides, nonionic polyacrylamides and the like. Examples of cationic polyacrylamides include polyacrylamides having functional groups such as amino groups, quaternary ammonium salts and azetidinium rings. Examples of the anionic polyacrylamide include polyacrylamides having a carboxyl group, a sulfone group and the like. As nonionic polyacrylamide, the polyacrylamide which has a hydroxyl group, an amide group, etc. is mentioned. In addition, amphoteric polyacrylamide is a polyacrylamide having both cationic and anionic functional groups.

(Water-soluble resin layer)
The water-soluble resin layer 2 of the foam / insulation paper container paper base 3 is provided on at least one side of the paper base 1. It is also possible to provide on both sides of the paper substrate 1.
By the presence of the water-soluble resin layer 2 on the surface of the paper substrate 1, the thermoplastic resin laminated on the water-soluble resin layer 2 in a later step firmly adheres to the paper substrate 1. As a result, the amount of water vapor supplied from the paper base 1 to the thermoplastic resin layer 4 at the time of foaming becomes even more, the over-foaming of the thermoplastic resin is suppressed, and the foaming form becomes uniform.
The water-soluble resin layer 2 is a layer containing a water-soluble resin as a main component, but if necessary, other resin components may be suitably contained within the range that does not hinder the effects of the invention.

(Formation amount of water-soluble resin layer)
It is preferable that it is 0.05-6.0 g / m < ² > in solid content, and, as for the formation amount per single side | surface of the water-soluble resin layer 2, it is more preferable that it is 0.08-2.0 g / m < ² >. When the formation amount of the water-soluble resin layer 2 is in this range, the thermoplastic resin layer 4 can be foamed uniformly, the foamed resin layer 9 can be thickened, and the heat insulating property is improved. When the amount of water-soluble resin layer 2 formed is in this range, the amount formed is appropriate, so that when the thermoplastic resin layer 4 is foamed, large irregularities and the like are unlikely to occur, and the aesthetics is enhanced. it can. Furthermore, when the amount of formation of the water-soluble resin layer 2 is in this range, equipment contamination in the paper making process or drying process can be reduced when the coating liquid is applied, and the contamination falls off and foreign matter in the foam insulation paper container 8 Can be prevented from becoming mixed.

If the amount of formation per one side of the water-soluble resin layer 2 is less than 0.05 g / m ² , uniform foaming can not be obtained, and as a result, irregularities may be generated on the surface, and the aesthetics may be impaired. On the other hand, when the formation amount per one side of the water-soluble resin layer 2 exceeds 6.0 g / m ² , the thermoplastic resin can not be sufficiently foamed, and the heat insulation may be insufficient.
The formation amount of the water-soluble resin layer 2 can be measured from the weight change before and after formation.

(Thickness of water-soluble resin to paper base)
When a coating solution containing a water-soluble resin is applied to the paper substrate 1, the coating solution penetrates from the surface of the paper substrate 1 to the inside. Thereafter, the coating liquid is solidified by drying to form the water-soluble resin layer 2. In the present embodiment, the water-soluble resin that has penetrated and solidified into the paper substrate 1 is also regarded as a part of the water-soluble resin layer 2.

  The penetration thickness of the water-soluble resin into the paper substrate 1 is preferably 5 to 35 μm, more preferably 10 to 30 μm, and still more preferably 15 to 25 μm. When the penetration thickness of the water-soluble resin into the paper substrate 1 is in this range, the thermoplastic resin layer 4 can be foamed uniformly, the thickness after foaming can be increased, and the heat insulation property is improved. Do. In addition, if the penetration thickness of the water-soluble resin into the paper base 1 is in this range, the permeation of water vapor generated from the paper base 1 can be appropriately barrierd, so that the dispersion of the transmission amount of water vapor can be reduced. . As a result, the foam cells can be made small and homogeneous, and the surface flatness and beauty can be enhanced.

If the permeation thickness of the water-soluble resin into the paper substrate 1 is less than 5 μm, the water-soluble resin layer 2 excessively blocks the permeation of water vapor, so that the thermoplastic resin layer 4 can be sufficiently foamed. It can not be done and there is a risk of reducing the heat insulation. On the other hand, if the penetration thickness of the water-soluble resin into the paper substrate 1 exceeds 35 μm, the water vapor transmission rate will not be uniform, the foaming will be non-uniform, and the beauty may be degraded.
The penetration thickness of the water-soluble resin into the paper substrate 1 can be appropriately adjusted depending on the pressure of the blade or rod, the size of the gap between the blade or rod and paper, the angle of the blade, the viscosity of the coating liquid, and the like. The penetration thickness of the water-soluble resin into the paper substrate 1 can be measured from an enlarged photograph of a cross section using an optical microscope, a scanning electron microscope, or the like.

(Air resistance)
The air permeation resistance (air permeation resistance / basis weight) per basis weight of the foam insulation paper container paper base 3 is preferably 1.0 to 6.0 s / g / m ² . When the air permeation resistance per grammage is in this range, the foam insulation paper container paper base 3 is supplied from the paper base 1 to the thermoplastic resin layer 4 when foaming the foam insulation paper container 8 described later. Modestly reduce the amount of water vapor. By this suppression, the foamed state of the thermoplastic resin layer 4 becomes uniform, so that the balance between the heat insulation property and the beautifulness of the foam insulation paper container 8 becomes good.
The air resistance per basis weight is more preferably 2.0 to 5.5 s / g / m ² , still more preferably 2.3 to 5.0 s / g / m ² , and particularly preferably 2.7 to 4 .5 s / g / m ² The air resistance is measured according to the Oken type testing machine method described in JIS P8117; 2009.

(Oken type smoothness)
The Oken-type smoothness of the foam insulation paper container paper base 3 is preferably 30 to 500 seconds. Wangken's smoothness is a unit that serves as an index for defining the smoothness of the paper surface. When the Oken type smoothness is 30 seconds or more, the surface property of the foam insulation paper container sheet base 3 is enhanced, and the foam insulation insulation paper container sheet 5 having a good surface quality can be obtained. Further, when the Oken type smoothness is 500 seconds or less, it is not necessary to crush the paper base 1 with a calender or the like in order to obtain high smoothness, and it is possible to suppress an extremely thin paper thickness. The molding processability of the heat insulating paper container 8 is improved.
The Oken type smoothness is measured according to JIS P8155: 2010.

(The formation index)
The formation index of the foam and heat insulating paper container paper base 3 is preferably 60 or more, more preferably 80 or more, and still more preferably 85 or more. The formation index is an index showing the uniformity of the paper (uniformity of basis weight of the micro, smoothness), and the larger the value, the better the formation. By setting the formation index to a predetermined value or more, the distribution of water content in the paper substrate 1 becomes uniform. Therefore, the permeation amount of the water vapor from the paper substrate 1 at the time of foaming becomes even more, the over-foaming is suppressed, and the foaming form becomes uniform. The formation index is obtained by measuring the transmission strength of the paper substrate 1 with a commercially available 3D sheet analyzer and quantifying the thickness variation. As a 3D sheet analyzer, for example, one manufactured by M / K Systems can be used.

(amount of water)
The water content of the foam insulation heat-insulating paper container paper base 3 is the sum of the water content contained in the paper base 1 and the water content contained in the partially saponified polyvinyl alcohol layer.
The moisture content contained in the paper substrate 1 is determined by the basis weight and the moisture content of the paper substrate 1. The moisture content of the foam insulation paper container paper base 3 is preferably 15 to 32 g / m ² , more preferably 20 to 23 g / m ² . The moisture content is measured according to JIS P8127; 2010 after humidity control.

(Basis weight)
The basis weight of the foam insulation paper container paper base 3 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 . If the basis weight is less than 100 g / m ² , foaming is likely to be insufficient due to the relationship of the water content, and heat is easily felt when the resulting foam insulation paper container 8 is gripped by hand. On the other hand, when the basis weight exceeds 400 g / m ² , the molding processability of the foam and insulation paper container 8 is lowered due to the increase of the rigidity, and the forming of the top curled part tends to be defective.

(Paper thickness)
The paper thickness of the foam insulation paper container paper base 3 is preferably 130 to 430 μm, more preferably 230 to 430 μm, and still more preferably 250 to 440 μm. If the paper thickness is less than 130 μm, foaming tends to be insufficient due to the relationship of the water content, and heat is easily felt when the resulting foam insulation paper container 8 is gripped by hand. On the other hand, if the basis weight exceeds 430 μm, the molding processability of the foam insulation paper container 8 is reduced due to the increase in rigidity, and there is a tendency for problems in the molding of the top curled part.

(density)
The density of the foam insulation paper container paper base 3 may be appropriately set according to the need, and is not particularly limited, but it is preferable to set it to 0.60 to 0.99 g / cm ³ .
When the density of the foam / insulation paper container paper base 3 is low, when foaming the thermoplastic resin layer 4, steam tends to easily pass through the paper base 1, and the foamability tends to be improved. However, if the density of the foam insulation paper container paper base ^{3 is} less than 0.60 g / cm ³ , the paper strength required for the foam insulation paper container 8 may not be obtained. On the other hand, when the density of the foam insulation paper container paper base 3 exceeds 0.99 g / cm ³ , when the thermoplastic resin layer 4 is made to foam, it is difficult for water vapor to pass through the paper base 1 and the foamability tends to decrease. There is.

(Z-axis strength)
In order to facilitate the formation of the top curled part, a foam insulation paper container sheet substrate 3 which is easily rounded is required.
The Z-axis strength refers to the strength in the direction perpendicular to the paper surface, that is, the strength between the paper layers, in other words, the internal bond strength between the paper layers. When the top curled portion is formed on the foam insulating heat-insulating paper container sheet base 3 having a small Z-axis strength, the paper layer which is the inside of the top curled portion is buckled and deformed following the paper layer which is the outside. This buckling deformation prevents the occurrence of cracking, peeling, and the like between the paper layer that is the inside and the paper layer that is the outside at the front end of the seam portion, and it is possible to suppress the curling of the seam portion.

The present inventors repeatedly studied the numerical range of the Z-axis strength which can realize the foam insulation / heat insulation paper container paper base 3 which is easy to form the top curl portion.
As a result, it was found that when the Z-axis strength is in the range of 380 to 560 kN / m ² , sufficient tensile strength can be maintained while securing sufficient roundness.
When the Z-axis strength is more than 560 kN / m ² , sufficient rounding easiness can not be secured, and there is a possibility that the seam portion may be curled up. From viewpoint of effectively suppressing curling of the seam portion, Z-axis strength is preferably not more than 540kN / ^{m 2,} and more preferably 520kN / ^{m 2} or less.
On the other hand, if the Z-axis strength is less than 380 kN / m ² , sufficient tensile strength can not be maintained, and there is a possibility that the top curled part may be broken or the like. From the viewpoint of effectively suppressing tear of the top curl portion, it is preferable that the Z-axis strength is 400 kN / ^{m 2} or more, more preferably 420kN / ^{m 2} or more.

As a method of adjusting the Z-axis strength, there is a method of appropriately increasing or decreasing the linear pressure in the pressing step in the paper making process. Other adjustment methods include a method of increasing or decreasing the NKP content relative to the pulp content, and a method of increasing or decreasing the disintegration freeness.
In addition, Z-axis strength is JAPAN TAPPI paper pulp test method No. 18-1: 2000 Paper and paperboard-Internal bond strength test method-Part 1: Measured according to the Z direction tensile test method.

(Tensile strength)
In order to facilitate the formation of the top curl portion, a foam insulation paper container sheet base 3 is required in which the paper base 1 is not broken by the tensile force at the time of top curl processing.

The present inventors repeatedly examined the numerical range of the tensile strength which can realize the foam insulation / heat insulation paper container paper base 3 which is easy to form the top curl portion.
As a result, it was found that when the tensile strength is in the range of 15.0 to 35.0 kN / m, breakage of the paper substrate 1 can be prevented during top curling.
If the tensile strength is more than 35.0 kN / m, the rigidity, the compressive force, and the like become large, and the ease of sufficient rounding can not be ensured, and there is a possibility that the seam portion may be curled up. The tensile strength is preferably 30.0 kN / m or less, more preferably 25.0 kN / m or less, from the viewpoint of effectively suppressing the curling of the seam portion.
On the other hand, if the tensile strength is less than 15.0 kN / m, the top curled part may be broken or the like. The tensile strength is preferably 15.5 kN / m or more, and more preferably 16.0 kN / m or more, from the viewpoint of effectively suppressing breakage of the top curled portion and the like.

As a method of adjusting the tensile strength, a method of increasing or decreasing the NKP compounding amount relative to the pulp compounding amount, a method of increasing or decreasing the disaggregation freeness, etc. may be mentioned.
The tensile strength was measured in accordance with the method defined in JIS P8113: 2006.

(Taber stiffness)
In order to facilitate top curling, a foam insulation paper container paper base 3 that is easy to curl, that is, has a small rigidity, is required.

The present inventors repeatedly examined the value of the Taber stiffness which can realize the foam insulation heat insulating paper container paper base material 3 which is easy to form the top curl portion.
As a result, it was found that when the Taber stiffness of the foam and insulation paper container paper base 3 is 17.0 kN · m or less, the foam and insulation paper container paper base 3 is easily rounded.
If the Taber stiffness is greater than 17.0 kN · m, sufficient rounding easiness can not be secured, and there may be a problem in the formation of the top curled portion. The taber stiffness is preferably 15.5 kN · m or less, and more preferably 14.0 kN · m or less, from the viewpoint of effectively suppressing defects in the formation of the top curled portion.
On the other hand, if the Taber stiffness is smaller than 12.0 kN · m, the foam insulation paper container 8 molded using the foam insulation paper container sheet base 3 tends to be easily deformed by the grip force. Therefore, the Taber stiffness is preferably 12.0 kN · m or more.

The Taber stiffness can be adjusted by increasing or decreasing the basis weight, paper thickness and the like.
The Taber stiffness was measured in accordance with the Taber Stiffness Tester method specified in JIS P8125: 2000.

  Here, in each case, the above-mentioned tensile strength and Taber stiffness are measured in principle in the MD direction (flow direction of the paper machine). However, when it is unclear which direction is the MD direction, the tensile strength is measured at every angle of 22.5 degrees, and the direction showing the strongest tensile strength is taken as the MD direction.

[Production method of foam insulation paper container paper base material]
The foam insulation paper container paper base 3 is manufactured by forming the water-soluble resin layer 2 on at least one side of the paper base 1. The method of forming the water-soluble resin layer 2 is not particularly limited, but a method of applying a water-soluble resin using a blade coater or a rod coater is preferable. By coating using a blade coater or a rod coater, it becomes possible to control the coating amount of the water-soluble resin and the permeation thickness to the paper substrate 1 uniformly. Then, by forming the water-soluble resin layer 2 in which the coating amount of the water-soluble resin and the penetration thickness to the paper base material 1 are within the predetermined range, the heat insulating property of the foam insulation paper container 8 and the beauty of the surface Can be improved together.

  The blade coater is an apparatus for applying a coating solution which has been applied once by a roll coater or the like by scraping it using a blade. That is, the blade coater obliquely disposes a blade (blade) having a length traversing the paper substrate 1 with respect to the paper substrate 1 so as to be disposed close to it. The blade scrapes off excess coating liquid that can not pass through the gap between the paper substrate 1 and the blade. The blade coater is a coater of a type in which the coating amount is adjusted by scraping off the coating liquid with a blade as described above.

  A rod coater is a device that applies a coating liquid that has been applied once by a roll coater etc. by scraping it using a smooth rod, a rod wound with a wire, or a rod having a large number of grooves on the surface. Yes, also called a bar coater. That is, the rod coater arranges a rod having a length traversing the paper base 1 close to the paper base 1. The said rod scrapes off the excess coating liquid which can not pass the clearance gap between the paper base material 1 and the said rod. The load coater is a coater of a type that adjusts the coating amount by scraping off the coating liquid with a rod in this manner.

  Both the blade coater and the rod coater can apply the coating solution at high speed and in a smooth manner, and can apply a high concentration coating solution thinly and uniformly. Therefore, a relatively high concentration coating liquid containing a water-soluble resin can be coated on the paper substrate 1 in a thin and uniform thickness. If it is a high concentration coating liquid containing a water-soluble resin, since the solution viscosity is high, penetration of the coating liquid into the paper base 1 after application to the paper base 1 is suppressed. Therefore, the penetration thickness of the water-soluble resin into the paper substrate 1 can be reduced. Moreover, when a high concentration coating liquid is used, the water-soluble resin concentration in the water-soluble resin layer 2 can be increased. From the above, even if the coating amount of the water-soluble resin is reduced, the water vapor generated from the paper substrate 1 can be uniformly and effectively barrierd.

  In the blade coater and the rod coater, the blade coater is preferable because the linear pressure at the time of scraping is higher than that of the rod coater, the coating amount can be precisely adjusted, and the uniformity of the film thickness is excellent.

  As coaters conventionally used, there are a calender size press and a two roll size press. In these coaters, in order to form a thin coating film, it was necessary to lower the concentration of the water-soluble resin to lower the solution viscosity. As a result, the coating liquid penetrates deeper into the paper substrate 1 and the concentration of the water-soluble resin in the water-soluble resin layer 2 is also low, and the water-soluble resin layer 2 is inferior in the ability to barrier water vapor generated from the paper substrate 1 It was formed.

  Water is usually used as a solvent for the coating liquid. If necessary, water-soluble organic solvents such as alcohol may be mixed and used. In the coating liquid, if necessary, a surfactant, an antifoaming agent, a dye, a pigment, a sizing agent, a water resistance agent, a paper strengthening agent, a dispersing agent, a plasticizer, a pH adjuster, an antifoaming agent, water retention You may use together various well-known adjuvants, such as an agent, antiseptic | preservative, a color dye, a color pigment, an ultraviolet protection agent.

  The method for drying the coating layer after applying the coating liquid is not particularly limited, and may be appropriately selected from methods used in a known paper making process or drying process. In addition, after the water-soluble resin layer 2 is formed, a smoothing treatment can be performed as needed. The smoothing process is performed on-machine or off-machine using a smoothing apparatus such as a normal super calender, a gross calendar, a soft calendar or the like.

[Sheet for foam insulation paper container]
As described above, the sheet 5 for foam insulation paper container according to the present embodiment has the thermoplastic resin layer 4 on at least one side of the paper base 1, and between the paper base 1 and the thermoplastic resin layer 4. And the water-soluble resin layer 2. The foam insulation sheet container sheet 5 is formed by providing the thermoplastic resin layer 4 on the water-soluble resin layer 2 of the foam insulation sheet container sheet base 3. Further, the heat contained in the paper base 1 and the water-soluble resin layer 2 is heated and evaporated by heat-treating the foam insulation sheet container sheet 5, and the thermoplastic resin layer 4 is formed with the foamed resin layer 9 by the generated water vapor. Become. Hereinafter, although the sheet | seat 5 for foaming insulation paper containers is demonstrated, description is abbreviate | omitted about the component demonstrated already.

(Thermoplastic resin layer)
The thermoplastic resin used for the thermoplastic resin layer 4 can be formed on the water-soluble resin layer 2 and is not particularly limited as long as it can be foamed. For the thermoplastic resin of the thermoplastic resin layer 4, any thermoplastic resin of crystalline resin and non-crystalline resin can be used.

Examples of the crystalline resin include polyolefin resins such as polyethylene, polypropylene and polymethylpentene, polyester resins, polyamide resins, polyacetal resins, polyphenylene sulfide (PPS) resins and the like.
Examples of non-crystalline resins include polystyrene, polyvinyl chloride, acrylonitrile butadiene styrene (ABS) resin, acrylic resin, modified polyphenylene ether (PPE), polycarbonate, polyurethane, polyvinyl acetate, non-crystalline polyethylene terephthalate (PET) Etc.).
In these thermoplastic resins, a single resin may be used in a single layer, a plurality of resins may be mixed and used, or two or more layers may be used.

Among the above-mentioned thermoplastic resins, polyethylene is preferred because of its excellent extrusion laminating properties and foaming properties. Polyethylene is largely linear low density polyethylene (density: 910 to 930 kg / m ³ , melting point: 102 ° C. to 122 ° C.), low density polyethylene (density: 910 to 930 kg / m ³ , melting point: 102 ° C. to 122 ° C. And medium density polyethylene (density: 930 to 942 kg / m ³ , melting point: 110 to 133 ° C.) and 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 property and foaming property.

  The thickness of the thermoplastic resin layer 4 is not particularly limited as long as the foam insulation paper container 8 having desired heat insulation is obtained, but from the viewpoint of heat insulation and processability, the thickness before foaming is 30 to 30 It is preferably 80 μm.

(High melting point thermoplastic resin layer, metal layer)
The sheet 5 for foam insulation paper container according to the present embodiment is a high melting point thermoplastic resin having a melting point higher than that of the thermoplastic resin layer 4 on the surface of the paper base 1 opposite to the surface on which the thermoplastic resin layer 4 is formed. The resin layer 10 or a metal layer such as an aluminum foil may be laminated.
Such a high melting point thermoplastic resin layer 10 and the metal layer formed the thermoplastic resin layer 4 of the paper substrate 1 when the thermoplastic resin layer 4 was foamed by heating the foam insulation sheet container sheet 5. Suppresses the evaporation of water vapor from the surface opposite to the surface. By suppressing the transpiration, sufficient steam is supplied to the thermoplastic resin layer 4 and the foamability of the thermoplastic resin layer 4 is improved.

  At this time, the melting point of the thermoplastic resin used for the high melting point thermoplastic resin layer 10 does not melt at the heating temperature at the time of heating and evaporating the water contained in the paper substrate 1 as long as it can prevent the diffusion of water vapor. Therefore, the melting point of the thermoplastic resin is not particularly limited, but is preferably 125 ° C. or more. Moreover, in order to form a metal layer on the surface of the paper base material 1, metal foil may be laminated | stacked and you may form a metal layer by vapor phase methods, such as a vapor deposition method.

  Furthermore, when the high melting point thermoplastic resin layer 10 or the metal layer is present on the inner wall surface side of at least one of the body member 6 and the bottom plate member 7 of the foam insulation paper container 8, the liquid etc. It is preferable because permeation can be suppressed.

  Alternatively, the high melting point thermoplastic resin layer 10 may be laminated on the thermoplastic resin layer 4 of the foam insulation sheet container sheet 5. When the high melting point thermoplastic resin layer 10 is laminated on the thermoplastic resin layer 4, the thermoplastic resin layer 4 is penetrated when the thermoplastic resin layer 4 is foamed by heating the foam insulation sheet container sheet 5. Transpiration of water vapor is suppressed. The suppression of the transpiration improves the foamability of the thermoplastic resin layer 4.

  In the case where the thermoplastic resin layer 4 is present on the outer wall surface side of the body member 6 of the foam and heat insulating paper container 8, generally the surface is not smooth because unevenness due to foaming occurs. When the high melting point thermoplastic resin layer 10 is laminated on the thermoplastic resin layer 4, the body surface of the foam insulation paper container 8 can be smoothed, so that the foam insulation paper container 8 having excellent beauty is obtained. be able to.

  The thermoplastic resin used for the high melting point thermoplastic resin layer 10 may be the same type as the thermoplastic resin used for the thermoplastic resin layer 4 or may be a different type. For example, consider the case where polyethylene is selected as both the thermoplastic resin used for the thermoplastic resin layer 4 and the thermoplastic resin used for the high melting point thermoplastic resin layer 10. In this case, by selecting low density polyethylene for the thermoplastic resin layer 4 and medium density polyethylene or high density polyethylene for the high melting point thermoplastic resin layer 10, the melting point of the high melting point thermoplastic resin layer 10 is thermoplastic resin. It can be higher than layer 4.

The difference between the melting points of the thermoplastic resin layer 4 and the high melting point thermoplastic resin layer 10, that is, the difference between the melting points of the thermoplastic resin used for the thermoplastic resin layer 4 and the thermoplastic resin used for the high melting point thermoplastic resin layer 10 is The temperature is preferably 5 ° C. or more.
When a plurality of types of resins are laminated and used in the thermoplastic resin layer 4 or the high melting point thermoplastic resin layer 10, the resin having the highest melting point in the thermoplastic resin layer 4 and the high melting point thermoplastic resin layer 10 It is preferable that the difference of the melting point is 5 ° C. or more for the resin having the lowest melting point.

The thickness of the high melting point thermoplastic resin layer 10 suppresses evaporation of water vapor from the surface of the paper substrate 1 opposite to the surface on which the thermoplastic resin layer 4 is laminated, or penetrates the thermoplastic resin layer 4. So long as it can suppress the evaporation of water vapor. Therefore, the thickness of the high melting point thermoplastic resin layer 10 is not particularly limited, but is preferably about 20 to 50 μm.
In particular, when the high melting point thermoplastic resin layer 10 is present on the inner wall surface side of at least one of the body member 6 and the bottom plate member 7 of the foam insulation paper container 8, the thickness of the high melting point thermoplastic resin layer 10 is 20 μm or more. Is preferred. If the thickness of the high melting point thermoplastic resin layer 10 is 20 μm or more, it is possible to effectively suppress the penetration of the liquid or the like filled in the container into the paper substrate 1.

[Production method of sheet for foam insulation paper container]
The foam and insulation paper container sheet 5 can be manufactured by forming the thermoplastic resin layer 4 on the foam and insulation paper container paper base 3 manufactured by the method described above.
Hereinafter, the sheet | seat formation process of a foam insulation paper container is demonstrated.

The method for forming the thermoplastic resin layer 4 is not particularly limited, and the thermoplastic resin layer 4 may be laminated using various methods such as an extrusion laminating method, a wet laminating method, and a dry laminating method as appropriate.
In the extrusion laminating method, a thermoplastic resin is extruded from the T die in the state of a molten resin film on the surface of the foam insulation paper container sheet substrate 3, and it is pressed while being cooled between the cooling roll and the nip roll opposed thereto. It is a method to crimp.
As a method of forming the thermoplastic resin layer 4, the adhesion between the water-soluble resin layer 2 and the thermoplastic resin layer 4 and the foamability of the thermoplastic resin layer 4 become good, and therefore the extrusion laminating method is preferable. The same applies to the method of forming the high melting point thermoplastic resin layer 10.

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

[Method for producing foam insulation paper container]
The foam and insulation paper container 8 forms the sheet 5 for foam and insulation paper container into a cup shape to produce a paper container (paper container forming step), and causes the obtained container to foam (foamed insulation paper container forming step) It can be manufactured.
Hereinafter, the paper container forming process and the foam insulating heat insulating paper container forming process will be described.

(Paper container molding process)
In the paper container forming step, the sheet 5 is used to form a paper container. The method for forming a paper container using the foam insulation sheet container sheet 5 is not particularly limited, and can be manufactured using a known method. As a specific example, there is a method of forming by a general cup forming machine described below.

  First, necessary printing is performed on a body member blank such as various patterns and bar codes at predetermined positions of the foam insulation sheet container sheet 5, and then the body member blank is punched into a predetermined shape. Positioning of the printed portion can be performed by a commonly used method.

  Next, a bottom plate member blank is prepared separately from the body member blank. The bottom plate blank can be manufactured by punching out the foam insulation sheet container sheet 5 in the same manner as the body blank. Moreover, in order to prevent that the liquid etc. with which the container was filled permeate | invade in the paper base material 1, a baseplate member blank can also be made into the structure different from the sheet | seat 5 for foam insulation paper containers of this embodiment. As the sheet used for the bottom plate member blank, for example, a sheet obtained by laminating a thermoplastic resin on a paper base 1, a sheet covered with an aluminum foil or the like can be used.

  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. When the same type of resin is used as the thermoplastic resin of the two or when both are produced from the same sheet 5 for foam insulation paper container, the body 6 and the bottom plate 7 simultaneously foam, so the foam insulation paper container is used. The heat insulation property of No. 8 is further improved. In particular, when the foam insulation paper container 8 is used outdoors, in winter, in cold regions, or when the foam insulation paper container 8 is used for a while after pouring hot water such as cup noodles, the foam insulation paper having the above-mentioned configuration The container 8 is effective.

  Next, the body member blank and the bottom plate member blank are assembled with a cup forming machine to form a container. The thermoplastic resin layer 4 may be present on one or both of the outer side and the inner side of the body member 6 when the body member blank and the bottom plate member blank are assembled into the shape of a container. Whether the thermoplastic resin layer 4 is formed on the outer side or the inner side of the body member 6 or on both sides may be appropriately determined depending on the desired heat insulation, aesthetics, touch, and the like.

(Foam insulation paper container molding process)
In the foam insulation paper container forming step, the paper container is subjected to heat treatment to form the foam insulation paper container 8. At this process, heat processing is performed with respect to the paper container shape | molded at the paper container formation process. When the heat treatment is carried out, the water contained in the body member blank of the paper container, the paper base 1 of the bottom plate member blank and the like is vaporized, and the generated water vapor causes the thermoplastic resin layer 4 to foam and becomes the foam insulation paper container 8 . The foam insulation paper container 8 uses the foam insulation paper 20 for at least one of the body member 6 and the bottom plate member 7, and the foam insulation paper 20 has a foam resin layer made of thermoplastic resin on at least one side of the paper substrate 1. It has nine.

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

  For the heat treatment, any means such as hot air, electric heat or electron beam can be used. Continuous heat treatment in a tunnel equipped with a conveyor means can produce the foam insulation paper container 8 at low cost and with high productivity.

  The thickness of the foamed resin layer 9 thus foamed is not particularly limited, but can be, for example, 800 to 1500 μm. When the thickness of the foamed resin layer 9 is 800 μm or more, sufficient heat insulation can be obtained. Moreover, when the thickness of the foamed resin layer 9 is 1500 μm or less, unevenness is unlikely to occur on the surface due to overfoaming, and there is no possibility that the beauty will be lost.

  In the foam insulation paper container 8 which concerns on this embodiment, the well-known technique in the field | area of paper containers can be applied in the range which does not impair a desired effect as needed. For example, a technique of applying a paint containing 5 to 40% by mass of a synthetic resin component to a part of the outside of the body member 6 to partially suppress foaming (Japanese Patent No. 3014629), the outside of the body member 6, ie, A technique of applying a synchronized ink to form a smooth printing surface in synchronization with foaming on the outer wall surface of the foam insulation paper container 8 (Japanese Patent No. 3408156), Forced processing of the opening upper edge of the body member 6 into a square cross section Although there is a technique (Japanese Patent Application Laid-Open No. 2001-354226) or the like in which an upper flange portion is formed and the inner winding end is polymerized on the upper portion of the flange portion to form a double structure (Japanese Patent Application Laid-Open No. 2001-354226). Moreover, in order to improve the aesthetics, an ink receiving layer containing as a main component a pigment and a binder may be provided on the outermost layer of the body member 6 which is the outer wall surface of the foam insulation paper container 8.

  Moreover, as a lid material used for the foam insulation paper container 8, what pierced the sheet | seat 5 for foam insulation paper containers can be used similarly to the said baseplate member blank. Moreover, in order to prevent that the liquid etc. with which the container was filled permeate | invade in the paper base material 1, a lid material can also be made into the structure different from the sheet | seat 5 for foam insulation paper containers which concern on this embodiment. As a sheet used for the lid, for example, a sheet obtained by laminating a thermoplastic resin on a paper base 1, a sheet covered with an aluminum foil or the like can be used.

  The foam insulation paper container 8 according to the present embodiment is a foam insulation paper container for filling hot coffee etc. used for an automatic vending machine etc., a foam insulation paper container for instant food into which hot water is injected, cooking for microwave oven Can be used as a container etc.

Examples and comparative examples are shown below. The materials, amounts used, proportions, treatment contents, treatment procedures and the like shown in the examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as limited by the specific examples shown below.
In addition, "part" and "%" in an Example and a comparative example show a "mass part" and "mass%", respectively unless it refuses.

Below, the measuring method implemented about the foam insulation paper container paper base material is shown.
Pulverization freeness (csf) was measured according to JIS P8121: 2012 for a pulp slurry obtained by disaggregating a foamed insulation paper container paper base according to JIS P8220: 2012.
The basis weight of the foam insulation paper container paper base was measured according to JIS P8124: 2011.
The paper thickness of the foam insulation paper container paper base was measured according to JIS P8118: 2014.
The density of the foam insulation paper container paper base was measured according to JIS P8118: 1998.

The tensile strength of the foam insulation paper container paper base was measured in the MD direction of the foam insulation paper container paper base according to the method defined in JIS P8113: 2006.
The Z-axis strength of the foam insulation paper container paper base is the same as the JAPAN TAPPI paper pulp test method No. 18-1: 2000 Paper and paperboard-Test method for internal bond strength-Part 1: Measured in the MD direction of the foam insulation paper container paper base according to the Z-axis direction tensile test method.
The Taber stiffness of the foam insulation paper container paper base was measured in the MD direction of the foam insulation paper container paper base according to the Taber Stiffness Tester method specified in JIS P8125: 2000.

Example 1
(Foam insulation paper container paper base material)
10 parts of NBKP and 90 parts of LBKP were mixed and refined to obtain a pulp slurry. 0.5% by mass of cationized starch, 0.1% by mass of polyacrylamide based paper strength agent (PAM based paper strength agent), alkyl ketene dimer system with respect to 100% by mass of the obtained pulp slurry (in terms of solid content) A stock slurry to which 0.30% by mass of sizing agent and 0.1% by mass of polyamidepolyamine epichlorohydrin resin (PAE-based wet paper strengthening agent) were added was subjected to one-layer paper making using a long screen paper machine.

Then, on both sides (the outermost layers of both sides) of the obtained paper substrate, an intermediate saponification type polyvinyl alcohol (PVA) (manufactured by Nippon Shokubai Bi-Poval Co., Ltd., product name: JM17, degree of saponification 96.5 mol%) ) Was coated and dried to give a solid content of 0.08 g / m ² (0.16 g / m ^{2 on} both sides) per one side, whereby a foam insulation paper container paper base material of Example 1 was obtained.
The foam insulation paper container paper base material of Example 1 has a basis weight of 303 g / m ² , a paper thickness of 341 μm, a density of 0.89 g / cm ³ , a Z axis strength of 553 kN / m ² , a tensile strength of 17.5 kN / m, and taber stiffness It was 13.8 mN · m.
The deaggregation freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Example 1 was 430 ml.

(Sheet for foam insulation paper container)
A thermoplastic resin with a high melting point (medium density polyethylene, density 940 kg / m ³ , melting point 133 ° C.) is melted at 360 ° C., lamination speed on one side of the foam insulation paper container paper base so as to be 40 μm thick It extruded at 50 m / min. Thereafter, using a cooling roll and a nip roll (JIS-A hardness: 70), pressure and pressure were applied at a linear pressure of 2 kgf / cm to form a high melting point thermoplastic resin layer.

Then, on the other side of the foam insulation paper container paper base, a thermoplastic resin (low density polyethylene, density 918 kg / m ³ , melting point 103 ° C.) is melted to a thickness of 50 μm, 360 ° C., lamination speed 50 m / It pushed out in a minute. Thereafter, using a cooling roll and a nip roll (JIS-A hardness: 70), pressing and pressure bonding are performed at a linear pressure of 2 kgf / cm to form a thermoplastic resin layer, and a sheet for foam insulation paper container of Example 1 is obtained. The

Example 2
100 parts of LBKP was beaten, and papermaking was conducted in the same manner as in Example 1; basis weight 298 g / m ² , paper thickness 331 μm, density 0.90 g / cm ³ , Z-axis strength 499 kN / m ² , tensile strength 18.3 kN / m The foam insulation paper container paper base of Taber stiffness 13.1 mN · m was obtained. The deaggregation freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Example 2 was 426 ml.
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 sheet for a foam insulation paper container of Experimental Example 2.

[Example 3]
Twenty parts of NBKP and 80 parts of LBKP are mixed and refined, and papermaking is carried out in the same manner as in Example 1; basis weight 300 g / m ² , paper thickness 335 μm, density 0.90 g / cm ³ , Z axis strength 514 kN / m ² , tensile strength 20 A foam insulation paper container paper base of 8 kN / m, Taber stiffness 14.0 mN · m was obtained. The deaggregation freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Example 3 was 520 ml.
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 sheet for a foam insulation paper container of Experimental Example 3.

Example 4
Papermaking was carried out in the same manner as in Example 1 except that starch was used as the water-soluble resin, and the basis weight was 302 g / m ² , paper thickness 341 μm, density 0.89 g / cm ³ , Z axis strength 539 kN / m ² , tensile strength A foam insulation paper container paper base of 17.4 kN / m and Taber stiffness 13.5 mN · m was obtained. The deaggregation freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Example 4 was 430 ml.
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 sheet for a foam insulation paper container of Experimental Example 4.

Comparative Example 1
100 parts of LBKP was beaten, and papermaking was conducted in the same manner as in Example 1; basis weight 300 g / m ² , paper thickness 335 μm, density 0.90 g / cm ³ , Z axis strength 376 kN / m ² , tensile strength 15.1 kN / m Thus, a foam insulation paper container paper base having a Taber stiffness of 12.9 mN · m was obtained. The disintegration freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Comparative Example 1 was 600 ml.
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 sheet for a foam insulation paper container of Comparative Example 1.

Comparative Example 2
Paper was prepared in the same manner as in Example 1; basis weight 302 g / m ² , paper thickness 341 μm, density 0.89 g / cm ³ , Z-axis strength 570 kN / m ² , tensile strength 32.6 kN / m, Taber stiffness 14.1 mN M A foam insulation paper container paper base was obtained. The deaggregation freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Comparative Example 2 was 420 ml.
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 sheet for a foam insulation paper container of Comparative Example 2.

Comparative Example 3
100 parts of LBKP was mixed and refined, and papermaking was conducted in the same manner as in Example 1; basis weight 303 g / m ² , paper thickness 342 μm, density 0.89 g / cm ³ , Z-axis strength 500 kN / m ² , tensile strength 14.5 kN / A foam insulation paper container paper base of m, Taber stiffness 13.3 mN · m was obtained. The deaggregation freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Comparative Example 2 was 540 ml.
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 sheet for a foam insulation paper container of Comparative Example 3.

Comparative Example 4
20 parts of NBKP and 80 parts of LBKP are mixed and refined, and papermaking is carried out in the same manner as in Example 1; basis weight 302 g / m ² , paper thickness 334 μm, density 0.88 g / cm ³ , Z axis strength 517 kN / m ² , tensile strength 21 A foam insulation paper container paper base of .5 kN / m and Taber stiffness of 17.7 mN · m was obtained. The deaggregation freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Comparative Example 2 was 470 ml.
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 sheet for a foam insulation paper container of Comparative Example 4.

Comparative Example 5
Papermaking was carried out in the same manner as in Example 1 except that the water-soluble resin was not used, and the basis weight was 302 g / m ² , the paper thickness 341 μm, the density 0.89 g / cm ³ , the Z axis strength 539 kN / m ² , the tension. A foam insulation paper container paper base having a strength of 17.4 kN / m and a Taber stiffness of 13.5 mN · m was obtained. The deaggregation freeness (csf) of the pulp obtained by redisintegrating the foam-insulated paper container paper base of Comparative Example 2 was 430 ml.
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 sheet for a foam and heat insulating paper container of Comparative Example 5.

[Evaluation method]
The following evaluation was performed about the sheet | seat for foam insulation paper containers obtained by making it above. The evaluation results were as described in Table 1. In addition, (circle) and (triangle | delta) are a pass, and x is a rejection.

(Formability of top curled part)
The top curled portion was visually observed when producing the obtained paper cup base paper, and was evaluated based on the following criteria.
:: No breakage, swelling, breakage, breakage, etc. observed in the top curled portion.
Fair: Some breakage, swelling, breakage, breakage, etc. are observed in the top curled part, but this is a practical level.
X: A large number of fractures, blisters, tears, breaks, etc. stand out in the top curl portion

(Cut off the seam)
The seam portion of the top curled portion was visually observed when producing the obtained paper cup base paper, and evaluation was performed based on the following criteria.
○: The seam part is not seen to curl up.
Fair: some curling up is observed at the seam portion, but this is a practical level.
X: Very many curling up at the seam portion is noticeable.

(Thermal insulation properties)
From the obtained sheet for foam insulation paper containers, a sample of A4 size was cut out. The cylinder was manufactured so that the thermoplastic resin layer was on the outside. Then, using a hot air, the thermoplastic resin layer on the outside of the cylinder was foamed at a heating temperature of 120 ° C. for 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 was evaluated based on the following criteria.
Good: Heat insulation is sufficient at an expansion ratio of 19 times or more.
B: Heat insulation is provided at an expansion ratio of 15 times or more and less than 19 times.
X: The heat insulation is insufficient at a foaming ratio of less than 15 times.

(Beauty)
From the obtained sheet for foam insulation paper containers, a square test piece of 100 mm on a side was cut out. Thereafter, using a hot air, the thermoplastic resin layer was foamed 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.
:: No over-foaming was observed, the formed foam cells were small and almost homogeneous, and the surface was also almost flat.
Δ: The formed foam cells are somewhat large, and there may be variation in size, but surface irregularities are small and no overfoaming is observed.
X: There are large irregularities on the surface, such as overfoaming.

As can be seen from Table 1, the sheets for foam insulation paper containers of Examples 1 to 4 are excellent in any of the formability of the top curled part, suppression of curling of the seamed part, heat insulating property, and beautifulness. The Moreover, it turned out that heat insulation and beauty are further excellent if PVA is used as water-soluble resin, and content of NKP is less than 10%.
The sheet for the foam insulation paper container of Comparative Example 1 had a Z-axis strength smaller than the appropriate range of the present invention, so the paper layer peeled off and the top curled part swelled and the seam part was very noticeable.
Since the sheet of the foam insulation paper container of Comparative Example 2 has a Z-axis strength greater than the appropriate range of the present invention, breakage, swelling, breakage, breakage, etc. of the top curled part is a practical level, but the curling of the seamed part is extremely high. Remarkable.
In the foam insulation paper container sheet of Comparative Example 3, since the tensile strength was smaller than the appropriate range of the present invention, breakage and the like of the top curled part was very noticeable.
The foam insulation paper container sheet of Comparative Example 4 had a Taber stiffness greater than the appropriate range of the present invention, and therefore, the top curled part was broken, and the seam part was very noticeable.
Since the sheet of the foam insulation paper container of Comparative Example 5 is not coated with the water-soluble resin on the paper base, the foam is not uniform, the surface beauty is inferior, and the sheet is not suitable for printing.

DESCRIPTION OF SYMBOLS 1 Paper base 2 Water-soluble resin layer 3 Foam insulation insulation paper container Paper base 4 Thermoplastic resin layer 5 Sheet for foam insulation paper container 6 Body member 7 Bottom plate member 8 Foam insulation paper container 9 Foam resin layer 10 High melting point thermoplastic resin Layer 20 foam insulation paper

Claims (6)

It is a foam insulation paper container paper base material comprising a paper base mainly composed of cellulose pulp and a water-soluble resin layer provided on at least one surface of the paper base,
Z-axis strength is 380 to 560 kN / m ² ,
The tensile strength in the MD direction is 15.0 to 35.0 kN / m,
A foam insulation paper container paper base material characterized by having a Taber stiffness in the MD direction of 17.0 mN · m or less measured in accordance with the Taber Stiffness Tester method specified in JIS P8125: 2000.   The foam insulation paper container paper base material according to claim 1, wherein a content of softwood kraft pulp with respect to the cellulose pulp is 20% by mass or less.   The foam insulation insulation paper container paper base material according to claim 1 or 2, characterized in that the disintegration freeness of the cellulose pulp measured in accordance with JIS P 8121: 2012 is 410 to 530 ml.   The water-soluble resin which comprises the said water-soluble resin layer is polyvinyl alcohol, Foaming insulation paper container paper base material of any one of Claims 1-3 characterized by the above-mentioned.   The sheet | seat for foam insulation paper containers which provided the thermoplastic resin layer on both surfaces of the foam insulation paper container paper base material of any one of Claims 1-4.   The foam insulation paper container which consists of a sheet | seat for foam insulation paper containers of Claim 5.

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