JP2022153685A - Method of producing barrier sheet and barrier sheet - Google Patents

Abstract

To provide a method of producing a barrier sheet excellent in gas barrier properties and flex resistance and a barrier sheet excellent in gas barrier properties and flex resistance.SOLUTION: Provided is a method of producing a barrier sheet including the steps of: bonding a base paper and a high-density cellulose sheet together by an adhesive having barrier properties; and drying the adhesive. Also provided is a barrier sheet in which a base paper, an adhesive layer having barrier properties and a high-density cellulose sheet are directly laid one over another in this order.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method for producing a barrier sheet that can be used for packaging materials and the like, and the barrier sheet.

One of the properties required for packaging materials is gas barrier properties. For example, if oxygen contained in the outside air enters the product container, the contents may deteriorate and deteriorate, shortening the shelf life. In addition, if the food or chemical product has a strong smell, the smell transferred from the product becomes a problem. Furthermore, when stored in an environment with a strong odor, odor transfer from the outside of the container to the contents becomes a problem.

Paper packaging materials are provided in which a metal foil or film is laminated on a paper substrate to impart gas barrier properties. As a material for forming the barrier layer, a metal foil or metal-deposited film made of a metal such as aluminum, a resin film such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyacrylonitrile, or a coating of these resins is used. There are films, and also ceramic vapor-deposited films obtained by vapor-depositing inorganic oxides such as silicon oxide and aluminum oxide.

Paper gas barrier materials having a gas barrier layer composed of a water-soluble polymer and an inorganic layered compound (Patent Documents 1 and 2) have been disclosed as paper packaging materials having gas barrier properties other than those described above.
Such a paper-made barrier packaging material may be bent during processing into a packaging container, transportation of a product, use, or the like, resulting in a significant deterioration in barrier properties. Therefore, there is a demand for a paper barrier packaging material with excellent flex resistance.

JP 2009-184138 A JP 2003-094574 A

An object of the present invention is to provide a method for producing a barrier sheet having excellent gas barrier properties and flex resistance, and a barrier sheet having excellent gas barrier properties and flex resistance.

Means for solving the problems of the present invention are as follows.
1. a step of laminating the base paper and the high-density cellulose sheet with an adhesive having barrier properties;
drying the adhesive;
A method for producing a barrier sheet, comprising:
2. 1. The adhesive comprises either a polyvinyl alcohol-based adhesive, cellulose nanofibers, or both. 3. The method for producing the barrier sheet according to 1.
3. 1. The high-density cellulose sheet is either glassine paper or cellulose nanofiber sheet. or 2. 3. The method for producing the barrier sheet according to 1.
4. A barrier sheet comprising a base paper, an adhesive layer having barrier properties, and a high-density cellulose sheet directly laminated in this order.
5. 4. The adhesive layer contains either a polyvinyl alcohol-based adhesive, a cellulose nanofiber, or both. The barrier sheet described in .
6. 4. The high-density cellulose sheet is either glassine paper or cellulose nanofiber sheet. or 5. The barrier sheet described in .

The method for producing a barrier sheet of the present invention can easily produce a barrier sheet having sufficient barrier properties and bending resistance through a simple process. The barrier sheet manufacturing method of the present invention enables continuous production, high productivity, and high yield.
The barrier sheet of the present invention is excellent in barrier properties and bending resistance.

The present invention provides a method for producing a barrier sheet comprising a step of laminating a base paper and a high-density cellulose sheet with an adhesive having a barrier property and a step of drying the adhesive, a base paper and an adhesive layer having a barrier property. , relates to a barrier sheet in which high-density cellulose sheets are directly laminated in that order.

"Manufacturing method of barrier sheet"
The barrier sheet manufacturing method of the present invention comprises a step of laminating a base paper and a high-density cellulose sheet with an adhesive having a barrier property, and a step of drying the adhesive.

・Base paper Base paper is obtained by making paper stock containing pulp, filler, various auxiliary agents, and the like.
As pulp, softwood bleached kraft pulp (NBKP), softwood unbleached kraft pulp (NUKP), hardwood bleached kraft pulp (LBKP), hardwood unbleached kraft pulp (LUKP), sulfite pulp (SP), etc. Wood Chemical Pulp, Ground Pulp (GP), Refiner Ground Pulp (RGP), Stone Ground Pulp (SGP), Chemi-Ground Pulp (CGP), Semi-Chemical Pulp (SCP), Thermo-Mechanical Pulp (TMP), Chemi-Thermomechanical Mechanical pulp of wood such as pulp (CTMP), non-wood pulp obtained from kenaf, bagasse, bamboo, hemp, straw, etc., waste paper pulp made from waste paper and the ink contained in waste paper is removed in the deinking process, etc. , known pulps can be appropriately mixed and used. Among these, chemical pulps such as NBKP are preferred for food contact applications.

Fillers include talc, kaolin, calcined kaolin, clay, heavy calcium carbonate, light calcium carbonate, white carbon, zeolite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, and aluminum hydroxide. , calcium hydroxide, magnesium hydroxide, zinc hydroxide, barium sulfate, inorganic fillers such as calcium sulfate, urea-formalin resins, polystyrene resins, phenolic resins, organic fillers such as fine hollow particles, etc. can be done. Note that the filler is not an essential material and may not be used.

Various auxiliaries include sizing agents such as rosin, alkylketene dimer (AKD), alkenylsuccinic anhydride (ASA), polyacrylamide-based polymers, polyvinyl alcohol-based polymers, cationized starch, various modified starches, urea, Formalin resin, dry paper strength enhancer such as melamine/formalin resin, wet paper strength enhancer, retention agent, drainage improver, coagulant, aluminum sulfate, bulking agent, dye, fluorescent whitening agent, pH adjuster, Antifoaming agents, anti-ultraviolet agents, anti-fading agents, pitch control agents, slime control agents and the like can be exemplified, and can be appropriately selected and used as necessary.

The base paper used in the present invention preferably has a weight of 25 g/m ² or more and 400 g/m ² or less. When the basis weight is within this range, it can be processed into various forms and used as a packaging material for foods, industrial materials, and the like. For example, when used as a soft packaging material that is a flexible packaging material, the basis weight is preferably 30 g/m ² or more and 110 g/m ² or less. Further, for example, when used as a rigid packaging material that can maintain a shape such as a box shape or a cylindrical shape, the basis weight is preferably 150 g/m ² or more and 350 g/m ² or less. If the basis weight is less than 150 g/m ² , the strength may be insufficient when used as a packaging material such as a box. When used for rigid packaging applications, if the basis weight exceeds 350 g/m ² , the processability may deteriorate. The basis weight of the base paper is preferably 200 g/m ² or more and 300 g/m ² or less, more preferably 210 g/m ² or more and 290 g/m ² or less, and 220 g/m ² or more and 280 g/m ² or less. It is even more preferable to have

- High-density cellulose sheet In the present invention, a high-density cellulose sheet means a sheet in which 90% by mass or more of the whole is composed of cellulose and whose density is 0.90 g/cm ³ or more. The high-density cellulose sheet used in the present invention is not particularly limited as long as it satisfies the above composition and density. Examples thereof include glassine paper, condenser paper, cellulose nanofiber sheet and the like.
A high-density cellulose sheet has an excellent gas barrier property due to its dense structure.

The cellulose nanofiber sheet, for example, has a degree of crystallinity of 70% or more, a degree of polymerization by a viscosity method using a copper ethylenediamine solution of 160 or less, and a fiber diameter of 50 nm or less, as described in JP-A-2013-256546. , a sheet containing 90% by mass or more of cellulose nanofibers, and a sheet obtained by coating a substrate with a cellulose nanofiber dispersion, drying it, and peeling it off from the substrate, as in Example 2 below. In addition, hereinafter, the cellulose nanofiber is also referred to as CNF in this specification.

Adhesive The present invention uses an adhesive having barrier properties as the adhesive. As the adhesive having a barrier property (hereinafter also referred to as a barrier adhesive), known adhesives having a barrier property can be used.・Synthetic adhesives such as acrylic, butadiene/methyl methacrylate, polyvinyl alcohol, maleic anhydride copolymer, and acrylic acid/methyl methacrylate; proteins such as casein, soybean protein, and synthetic protein; starch, oxidation starch, positive starch, etherified starch such as urea phosphate esterified starch, hydroxyethyl etherified starch, starch such as dextrin; adhesives such as cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose; can be used alone or in combination of two or more thereof. Among these, it is preferable to include either or both of polyvinyl alcohol-based adhesives such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and ethylene-copolymerized polyvinyl alcohol, and cellulose nanofibers.

As a barrier adhesive, cellulose nanofibers can be used alone or mixed with other adhesives. The cellulose nanofibers are fine fibers obtained by fibrillating cellulose-based raw materials.
The average fiber diameter of the cellulose nanofibers used in the present invention is preferably 1 to 200 nm, more preferably about 2 to 100 nm. The average fiber length of the cellulose nanofibers used in the present invention is preferably 40 to 2,000 nm, more preferably about 100 to 1,000 nm. The average fiber diameter and average fiber length of cellulose nanofibers are the fiber diameter and fiber length obtained from the results of observing 30 or more fibers using an atomic force microscope (AFM) or transmission electron microscope (TEM). can be obtained by averaging In this specification, the description "A to B (A and B are numbers)" means a numerical range including the values of A and B, that is, from A to B and below.

In the present invention, when cellulose nanofibers are used as an adhesive, it is preferable to use chemically modified cellulose nanofibers obtained by chemically modifying cellulose-based raw materials and then fibrillating them. It is more preferable to use anion-modified cellulose nanofibers such as modified cellulose.
In the case of carboxylated cellulose, the amount of carboxyl groups relative to the absolute dry weight of cellulose nanofibers is preferably 0.6 mmol/g or more, more preferably 0.8 mmol/g or more, and still more preferably 1.0 mmol/g or more. . The upper limit is preferably 2.2 mmol/g or less, more preferably 2.0 mmol/g or less, still more preferably 1.8 mmol/g or less. Therefore, it is preferably 0.6 mmol/g to 2.2 mmol/g, more preferably 0.8 mmol/g to 2.0 mmol/g, even more preferably 1.0 mmol/g to 1.8 mmol/g.

For carboxyalkylated cellulose, it is preferred that the degree of carboxyalkyl substitution per anhydroglucose unit of the cellulose is less than 0.60. Furthermore, when the anionic group is a carboxymethyl group, the degree of carboxymethyl substitution is preferably less than 0.60. If the degree of substitution is 0.60 or more, the crystallinity is lowered and the ratio of dissolved components is increased, so that the function as nanofibers is lost. Also, the lower limit of the degree of carboxyalkyl substitution is preferably 0.01 or more. Considering workability, the degree of substitution is particularly preferably 0.02 to 0.50, more preferably 0.10 to 0.30.
Phosphate-esterified cellulose is preferable as the esterified cellulose. By introducing a phosphate group or a phosphite group into cellulose, the celluloses electrically repel each other, so that the phosphate-esterified cellulose can be easily nanofibrillated. More preferably, the degree of phosphate group substitution per glucose unit of cellulose is 0.001 or more and less than 0.40. If the degree of phosphate group substitution per glucose unit is less than 0.001, sufficient nanofibrillation cannot be achieved. On the other hand, if the degree of phosphate group substitution per glucose unit is greater than 0.40, the nanofibers may not be obtained due to swelling or dissolution.

(cellulosic raw material)
Cellulosic raw materials used for the production of CNF include plants (for example, wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, waste paper, etc.), animals (e.g., sea squirts), algae, microorganisms (e.g., Acetobacter), microbial products, etc. are known, and any of them can be used in the present invention.Cellulose fibers derived from plants or microorganisms. is preferred, and plant-derived cellulose fibers are more preferred.

The barrier adhesive used in the present invention is preferably water-soluble or water-dispersible. The solid content concentration of the barrier adhesive is preferably 1.0% by mass or more and 20% by mass or less. If the solid content concentration is less than 1.0% by mass, the time required for drying may become too long. If the solid content concentration is higher than 20% by mass, the viscosity may become too high, resulting in poor handleability and coatability.
Although the coating amount of the barrier adhesive is not particularly limited, it is preferably 0.1 g/m ² or more and 10 g/m ² or less in terms of solid content. If the coating amount is less than 0.1 g/m ² , the adhesive strength and barrier properties may deteriorate. If the coating amount exceeds 10 g/m ² , the time required for drying may become too long.

The barrier adhesive can be applied to either or both of the base paper and the high density cellulose sheet using a known coating machine such as a roll coater, blade coater, air knife coater, bar coater, die coater and curtain coater. can. A known laminating apparatus can be used for laminating the base paper and the high-density cellulose sheet.
After laminating the base paper and the high-density cellulose sheet with an adhesive having a barrier property, the adhesive is dried. Drying can be performed by a known drying device such as a steam heater, gas heater, infrared heater, electric heater, hot air heater, microwave, cylinder dryer, and the like.

In the method for producing the barrier sheet of the present invention, the gas barrier property of the barrier adhesive layer can be maintained at a high level by drying the barrier adhesive after lamination. This is because when the barrier adhesive is dried with one side exposed, when the liquid dries (evaporates) from the exposed surface of the barrier adhesive layer, microscopic holes through which oxygen atoms can pass are generated. On the other hand, when the barrier adhesive layer is sandwiched between the base paper and the high-density cellulose sheet and dried, the liquid content is mainly absorbed by the base paper and dries (volatilizes) from the base paper. It is presumed that this is because there are no microscopic holes through which oxygen atoms or the like can pass.

The method for producing the barrier sheet of the present invention only needs to have the lamination step and the drying step described above, and may have other steps. For example, a lamination process in which a coating layer is provided on the side opposite to the side of the base paper coated with the barrier adhesive to provide printability, etc. It can include a laminating step of providing a thermoplastic resin layer on one surface, a creasing step of providing creasing lines (folding lines) when forming a box-shaped container by folding, and the like.

"barrier sheet"
In the barrier sheet of the present invention, a base paper, an adhesive layer having barrier properties, and a high-density cellulose sheet are directly laminated in this order. The base paper, the high-density cellulose sheet, and the adhesive having barrier properties can each be used as described above.
In the barrier sheet of the present invention, since the molecular structure of the adhesive layer having a barrier property (hereinafter also referred to as a barrier adhesive layer) and the high-density cellulose sheet are dense, oxygen atoms and the like are difficult to permeate, resulting in excellent gas barrier properties. ing. In the present invention, one of the barrier adhesive and the high-density cellulose sheet preferably contains cellulose nanofibers, and both contain cellulose nanofibers, in order to form a denser structure and prevent permeation of oxygen atoms and the like. is more preferred. Furthermore, in the barrier sheet of the present invention, the high-density cellulose sheet acts as a protective layer, and the barrier adhesive layer is less likely to crack, so the barrier sheet is excellent in flex resistance and suppresses deterioration of gas barrier properties after folding or the like. can be done. Therefore, the barrier sheet of the present invention can be used as a barrier sheet, laminated with various resins such as a coat layer and a thermoplastic resin layer, or laminated with various general-purpose films, barrier films, aluminum foil, etc., to be used as a food product. It can be used as a packaging material such as a container, a paper barrier packaging material used for packaging applications such as a cup, or a laminate used for industrial materials. Among these, it can be suitably used as a paper barrier packaging material used for packaging such as food packaging materials, containers, cups and the like.

When the barrier sheet of the present invention is used as a packaging material for food or the like, by laminating a resin layer having heat-sealing properties on one or both sides of the barrier sheet, the sealing performance of the packaging material is improved and the contents are protected from oxygen. It is possible to extend the storage period by protecting it from oxidation due to heat and deterioration due to humidity. In addition, when used as a laminate for industrial materials, it can prevent rotting and deterioration by suppressing the intrusion of oxygen and moisture. effect is expected.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. In this specification, all "%" means "% by mass" unless otherwise specified, and the numerical range includes the endpoints thereof.

(Example 1)
<Preparation of base paper>
Hardwood kraft pulp (LBKP) with a Canadian standard freeness (CSF) of 400 ml and softwood kraft pulp (NBKP) with a CSF of 450 ml were blended at a mass ratio of 20/80 to obtain raw material pulp.
0.1% of polyacrylamide (PAM) having a molecular weight of 2.5 million per absolute dry pulp weight as a dry paper strength enhancer, and 0.35% of alkyl ketene dimer (AKD) as a sizing agent per absolute dry pulp weight. %, 0.15% of polyamide epichlorohydrin (PAEH) based resin as a wet paper strength agent per absolute dry pulp mass, and polyacrylamide (PAM) with a molecular weight of 10 million as a retention agent relative to absolute dry pulp mass. After adding 0.08% per unit area, paper was made with a Fourdrinier machine to obtain a base paper with a basis weight of 250 g/m ² .

<Preparation of carboxymethylated CNF>
200 g of dry mass of bleached kraft pulp (BKP, manufactured by Nippon Paper Industries Co., Ltd.) and 111 g of sodium hydroxide are added to a stirrer capable of mixing pulp, and water is added so that the solid content of the pulp becomes 20% by mass. was added. Then, after stirring at 30° C. for 30 minutes, 216 g of sodium monochloroacetate (converted to active ingredient) was added. After stirring for 30 minutes, the temperature was raised to 70° C. and the mixture was stirred for 1 hour. After that, the reactant was discharged, neutralized, and washed to obtain a carboxymethylated pulp having a degree of carboxymethyl substitution of 0.25 per glucose unit.
Thereafter, the carboxymethylated pulp was adjusted to a solid content of 1% with water, and defibrated by a high-pressure homogenizer at 20° C. and a pressure of 150 MPa five times to obtain an aqueous dispersion of carboxymethylated CNF. The obtained carboxymethylated CNF had an average fiber diameter of 50 nm and an aspect ratio of 120.

<Preparation of Adhesive A (CNF/PVA)>
Add 1000 g of the carboxymethylated CNF aqueous dispersion (solid content 1.0%) obtained above to 100 parts of polyvinyl alcohol (trade name: PVA-105, solid content 10%, manufactured by Kuraray Co., Ltd.). After that, the mixture was kept at 25° C. with stirring to obtain a CNF/PVA adhesive having a barrier property.

<Production of Sheet 1>
On the base paper (basis weight: 250 g/m ² ) produced above, adhesive A was applied using a Meyer bar so that the coating amount (dry mass) was 1.5 g/m ² , and the adhesive dried. Before heating, it was pasted with glassine paper (basis weight: 17 g/m ² , manufactured by Nippon Paper Papylia Co., Ltd.), which is a high-density cellulose sheet, and dried at 80°C to prepare sheet 1 .

The obtained sheet 1 was evaluated as follows. Table 1 shows the results.
<Measurement of Basis Weight>
Measured according to JIS P 8124:2011.
<Measurement of air resistance of sheet>
The sheet obtained above was measured according to JIS P 8117:2009.
<Measurement of sheet air resistance after bending>
A sheet having a side of 10.0 cm was used as a test piece. A test piece folded in two with the CD axis as the folding axis is pressurized in a nip processing device consisting of metal rolls/metal rolls at a passing direction perpendicular to the folding axis, a passing speed of 50 m/min, and a nip pressure of 5 kN/m. and returned to the original square.
The obtained sheet after the bending treatment was measured according to JIS P 8117:2009.

<Measurement of oxygen permeability of sheet>
The sheet was laminated with a low-density polyethylene (LC602A manufactured by Japan Polyethylene Co., Ltd.) to a thickness of 30 μm by extrusion lamination to obtain laminated paper.
The gas permeability of this laminated paper was measured by a differential pressure method under oxygen introduction pressure of 107 kPa, 23° C. and 0% RH using a gas permeability measuring device (K-315N-03) manufactured by Tsukubarika Seiki Co., Ltd.
<Measurement of sheet oxygen permeability after bending>
The laminated paper obtained above was cut into a square having a side of 10.0 cm to obtain a test piece. A test piece folded in two with the CD axis as the folding axis is pressurized with a nip processing device consisting of metal rolls/metal rolls, with the passing direction perpendicular to the folding axis, the passing speed of 50 m/min, and the nip pressure of 50 kN/m. Then return to the original square. The laminated paper obtained after the folding treatment was measured by a differential pressure method using a gas permeability measuring device (K-315N-03) manufactured by Tsukubarika Seiki Co., Ltd. under oxygen introduction pressure of 107 kPa, 23° C., and 0% RH. did.

<Destruction evaluation of resin layer by bending in molding process>
Both sides of the postcard-sized sheet were printed in solid black with a laser beam printer (CASION N5300), and each side was laminated with a low-density polyethylene resin to a thickness of 30 μm by extrusion lamination. The obtained laminated sheet was cut into a square having a side of 10.0 cm to obtain a test piece. A test piece folded in two with the CD axis as the folding axis is pressurized with a nip processing device consisting of metal rolls/metal rolls, with the passing direction perpendicular to the folding axis, the passing speed of 50 m/min, and the nip pressure of 50 kN/m. did. After the pressure treatment, damage to the resin layer on both sides of the folding axis portion was visually observed and evaluated according to the following criteria.
A: Destruction of the resin layer is not observed.
◯: Destruction of the resin layer is slightly observed, but only one side is destructed, and there is no practical problem.
Δ: Destruction of the resin layer is observed, and the destruction extends to both surfaces.
x: Large breakage of the resin layer is observed.

(Example 2)
<Production of carboxylated (oxidized) cellulose>
500 g (absolutely dry) of bleached unbeaten kraft pulp (85% whiteness) derived from softwood is added to 500 ml of an aqueous solution of 780 mg of TEMPO (Sigma Aldrich) and 75.5 g of sodium bromide, until the pulp is uniformly dispersed. Stirred. An aqueous sodium hypochlorite solution was added to the reaction system so as to have a concentration of 6.0 mmol/g to initiate an oxidation reaction. The pH in the system decreased during the reaction, but was adjusted to pH 10 by successively adding 3M sodium hydroxide aqueous solution. The reaction was terminated when the sodium hypochlorite was consumed and the pH in the system stopped changing. The mixture after the reaction was filtered through a glass filter to separate pulp, and the pulp was thoroughly washed with water to obtain carboxylated cellulose (sodium salt). At this time, the pulp yield was 90%, the time required for the oxidation reaction was 90 minutes, and the amount of carboxyl groups was 1.45 mmol/g.

<Preparation of carboxylated CNF>
The above carboxylated cellulose was adjusted to a solid content of 1% with water, and fibrillated by treatment with an ultrahigh pressure homogenizer at 20° C. and a pressure of 150 MPa five times to obtain a dispersion of carboxymethylated CNF. The obtained carboxymethylated CNF had an average fiber diameter of 3 nm and an aspect ratio of 230.
<Creation of cellulose nanofiber sheet>
After casting the carboxylated CNF dispersion on a PET film with a Meyer bar (No. 40), drying with a hand dryer, peeling from the PET film, a cellulose nanofiber sheet with a thickness of 20 μm, which is a high-density cellulose sheet. got

<Preparation of adhesive B (PVA)>
While stirring the water, polyvinyl alcohol (trade name: PVA-105, manufactured by Kuraray Co., Ltd.) was gradually added so as to have a concentration of 10%, and the water was heated while stirring. After the temperature reached 95° C., stirring was continued for about 1 hour while maintaining the temperature. After that, the heat was turned off, the stirring was reduced, and the mixture was gradually cooled. By further diluting with water to a concentration of 5%, a PVA adhesive having barrier properties was obtained.
<Production of Sheet 2>
In the same process as in Example 1, except that the cellulose nanofiber sheet produced above was used instead of the glassine paper used in Example 1, and the adhesive B was used instead of the adhesive A for lamination. A sheet 2 was produced and each evaluation was performed. Table 1 shows the results.

(Comparative example 1)
<Preparation of adhesive C (vinyl acetate)>
To 18.2 parts of vinyl acetate (trade name: quick-drying bond for woodworking, solid content 55%, manufactured by Konishi Co., Ltd.), water was added so that the solid content was 10% concentration, and the mixture was stirred for 25 minutes. C. to obtain a vinyl acetate adhesive that does not have a barrier property.
<Create sheet 3>
A sheet 3 was produced in the same manner as in Example 1, except that the adhesive C was used instead of the adhesive A used in Example 1, and each evaluation was performed. Table 1 shows the results.

Claims (6)

a step of laminating the base paper and the high-density cellulose sheet with an adhesive having barrier properties;
drying the adhesive;
A method for producing a barrier sheet, comprising: 2. The method of manufacturing a barrier sheet according to claim 1, wherein the adhesive contains polyvinyl alcohol-based adhesive, cellulose nanofiber, or both. 3. The method for producing a barrier sheet according to claim 1, wherein the high-density cellulose sheet is either glassine paper or cellulose nanofiber sheet. A barrier sheet comprising a base paper, an adhesive layer having barrier properties, and a high-density cellulose sheet directly laminated in this order. 5. The barrier sheet according to claim 4, wherein the adhesive layer contains polyvinyl alcohol-based adhesive, cellulose nanofiber, or both. 6. The barrier sheet according to claim 4 or 5, wherein the high-density cellulose sheet is either glassine paper or cellulose nanofiber sheet.