JP2023074651A - Packaging sheet - Google Patents

Abstract

To provide a packaging sheet that has heat sealability and excels in heat distortion resistance and an oxygen barrier property.SOLUTION: A packaging sheet comprises a paper substrate, a barrier layer disposed on at least one side of the paper substrate, and a heat seal layer disposed on the outside of the barrier layer relative to the paper substrate, the barrier layer comprising inorganic laminar minerals and polyhydroxy urethane.SELECTED DRAWING: None

Description

The present invention relates to a paper-based wrapping paper having heat-sealing properties.

Due to the problem of environmental pollution caused by microplastics and the like, there are already packaging papers that use paper as the base material instead of plastic sheets. For example, at least one surface of a paper substrate has at least two or more coating layers, the outermost surface of the coating layer is a heat seal layer, and at least BACKGROUND ART A packaging paper having oxygen barrier properties is known which has a single barrier layer and is characterized in that the barrier layer contains polyhydroxyurethane (see, for example, Patent Document 1). However, in the packaging paper described in Patent Document 1, the oxygen permeability of the packaging paper was tested under test conditions of 20 ° C. and 80% in accordance with JIS K7126-1: 2006, and adhesive was applied to both sides of the packaging paper. A test piece laminated with stretched polypropylene is measured with an oxygen permeability measuring device, and an oxygen permeability of 100 cc/m ² ·day·atm or less is considered to have oxygen barrier properties.

JP 2021-138434 A

The packaging paper as described in Patent Literature 1 still has insufficient oxygen barrier properties when the packaging paper is measured.
In addition, although polyurethane such as polyhydroxyurethane is a resin having barrier properties, it undergoes large thermal deformation. Then, the barrier layer is thermally deformed, and as a result, the heat-sealed portion may be wrinkled, misaligned, and twisted, resulting in poor appearance. In particular, packaging paper, which is a paper base material, is more likely to wrinkle, shift, and twist than a packaging material whose base material is a plastic sheet. Further, although polyurethane is less harmful than conventionally known resins having barrier properties such as polyvinylidene chloride, its barrier properties are not relatively high due to its molecular structure.

SUMMARY OF THE INVENTION An object of the present invention is to provide a packaging paper having heat-sealing properties, a barrier layer containing polyurethane as the main component of the resin, and excellent resistance to heat deformation and oxygen barrier properties.

The inventors of the present invention have made intensive studies on a packaging paper that is a barrier layer containing polyurethane as the main component of the resin and that is excellent in heat deformation resistance and oxygen barrier properties. As a result, the inventors have found the configuration of the present invention and have achieved the object of the present invention.

[1] A paper substrate, a barrier layer on at least one side of the paper substrate, and a heat seal layer on the outside of the barrier layer with reference to the paper substrate, wherein the barrier layer is an inorganic layer A wrapping paper containing minerals and polyhydroxyurethane.

[2] The wrapping paper according to [1] above, wherein the inorganic layered mineral contains mica.

[3] The wrapping paper according to [2] above, wherein the mica has an aspect ratio of 100 or more.

The packaging paper of the present invention has a heat-sealing property, a barrier layer containing polyurethane as a main component of the resin, and is excellent in heat deformation resistance and oxygen barrier property.

The packaging paper has a paper substrate and a barrier layer on at least one side of the paper substrate. In addition, the packaging paper has a heat-seal layer on the outer side of the barrier layer with respect to the paper substrate. In the wrapping paper embodiment, the side of the wrapping paper that faces the package and contents is the side of the wrapping paper that has the heat seal layer and the barrier layer. In some embodiments, the wrapping paper has a barrier layer and a heat seal layer on both sides of the paper substrate. The reason for this is that it is superior in handling because it can be used regardless of the front and back. In some embodiments, when the wrapping paper has a barrier layer and a heat seal layer on only one side of the paper substrate, the paper substrate is gravure or digital printed on the opposite side of the paper substrate having these layers. It has conventionally known coating layers for printability on press or for dimensional stability. In some embodiments, the packaging paper contains pigments and resins to further improve the barrier properties between the paper substrate and the barrier layer, or to fill voids in the paper substrate. It has a conventionally known coating layer. In at least one embodiment, the packaging paper does not have a coating layer containing pigments and resins between the paper substrate and the barrier layer. The reason for this is that it is superior in terms of manufacturing cost.

The heat-sealing layer contains a resin having heat-sealing properties. The heat-sealable resin is not particularly limited, and is, for example, a conventionally known thermoplastic resin. Examples of thermoplastic resins include polyolefin-based resins such as polyethylene, modified polyolefin-based resins, ethylene-vinyl acetate-based copolymer resins, styrene-butadiene-based copolymer resins, styrene-acrylic copolymers, ethylene-acrylic copolymers, and the like. and acrylic resins. The heat seal layer has a layer structure of one layer or two or more layers. In some embodiments, the heat seal layer is one layer. The reason for this is that it is superior in terms of manufacturing cost.
In some embodiments, the wrapping paper has other conventionally known barrier layers such as a water vapor barrier layer and a gas barrier layer between the barrier layer and the heat seal layer to further improve barrier properties. In at least one embodiment, the wrapping paper has no other barrier layer between the barrier layer and the heat seal layer. The reason for this is that it is superior in terms of manufacturing cost.

The heat-sealing layer may contain conventionally known various additives as needed in addition to the heat-sealable resin. Additives include, for example, inorganic pigments, organic pigments, waxes such as paraffin wax, various resins other than resins having heat-sealing properties, polysaccharides such as starches and celluloses, surfactants, dispersants, and thickeners. , a water retention agent, an antifoaming agent, a water resistance agent, a coloring agent, an ultraviolet absorber, a fluorescent agent, and the like.

In some embodiments, the coating amount of the heat seal layer is 5 g/m ² or more and 25 g/m ² or less as dry solids per side of the paper substrate. The reason for this is that the heat sealability can be stably obtained, and layer defects that may occur in the barrier layer due to voids in the paper substrate can be closed.

The paper base material is a paper material obtained by adding various additives such as fillers, sizing agents, binders, fixing agents, retention agents, and paper strength agents to a slurry composed of wood pulp and/or non-wood pulp as necessary. , paper made by a conventionally known papermaking method under acidic, neutral or alkaline conditions, base paper obtained by size-pressing the paper with a size press liquid, base paper obtained by surface-treating the paper with a surface treatment liquid, or It is paper made from paper or plain paper obtained by subjecting the base paper to calendering. Other additives such as pigment dispersants, bulking agents, thickeners, fluidity improvers, pitch control agents, antifoaming agents, foam inhibitors, release agents, foaming agents, penetrating agents, moisturizing agents, and One or two or more selected from agents, preservatives, anti-baking agents, water resistance agents, wet paper strength agents, dry paper strength agents, etc. are added as appropriate to the extent that the desired effects of the present invention are not impaired. be able to.
In addition, examples of paper substrates include coated paper obtained by forming a coating layer on the above-mentioned paper, base paper, or plain paper, kraft paper, one-sided glossy paper, and tracing paper.

Calendering is a process in which smoothness and thickness are averaged by passing paper between rolls. Examples of calendering devices include machine calenders, soft nip calenders, super calenders, multi-stage calenders, and multi-nip calenders.

Wood pulp is conventionally known in the papermaking arts. Wood pulp includes, for example, chemical pulps such as LBKP (Leaf Bleached Kraft Pulp) and NBKP (Needle Bleached Kraft Pulp), GP (Groundwood Pulp), PGW (Pressure GroundWood pulp), RMP (Refiner Mechanical Pulp), TMP (ThermoMechanical Pulp). ), CTMP (ChemiThermoMechanical Pulp), CMP (ChemiMechanical Pulp) and CGP (ChemiGroundwood Pulp), and waste paper pulp such as DIP (DeInked Pulp).
Non-wood pulp is pulp composed of non-wood fibers conventionally known in the paper industry. Raw materials for non-wood fibers include, for example, woody basts such as paper mulberry, mitsumata and gampi, herbaceous basts such as flax, hemp and kenaf, leaf fibers such as manila hemp, abaca and sisal hemp, rice straw, wheat straw, and sugarcane. Mention may be made of monocotyledonous plants such as bacchus, bamboo and esparto, and seed hairs such as cotton and linters.
The wood pulp and/or non-wood pulp is one or more selected from the group consisting of the wood pulp and the non-wood pulp.

Fillers are pigments conventionally known in the papermaking arts. Pigments include, for example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, silica, aluminum silicate, diatomaceous earth, activated clay, alumina, and alumina water. Inorganic pigments such as hydrates, aluminum hydroxide, lithopone, zeolite, magnesium carbonate and magnesium hydroxide can be mentioned. Furthermore, organic pigments such as styrene plastic pigments, acrylic plastic pigments, polyethylene plastic pigments, urea resins, melamine resins and microcapsules can be used. The filler is one or more selected from the group consisting of the inorganic pigments and the organic pigments.
In some embodiments, the paper substrate is substantially free of fillers. The reason for this is that the oxygen barrier properties of the wrapping paper are improved. Here, "substantially free of fillers" means that the content of fillers is below the level at which the fillers increase the air permeability of the paper. For example, the filler is less than 0.5% by weight with respect to 100 parts by weight of pulp in the paper base.

In some embodiments, the paper substrate has an ash content of 3% by weight or less. The reason for this is that if the ash content of the paper base material is 3% by mass or less, the air permeability of the paper base material itself decreases, which is advantageous for the oxygen barrier properties of the resulting packaging paper. The ash content of the paper substrate is a value determined in accordance with ISO 1762:2001 "Paper, board and pulps - Determination of residue (ash) on ignition at 525 degree C".

The sizing agent is an internal sizing agent conventionally known in the papermaking art. Examples of internal sizing agents include rosin-based sizing agents for acidic paper, and alkenyl succinic anhydride, alkylketene dimers, neutral rosin-based sizing agents, and cationic styrene-acrylic sizing agents for neutral paper. be able to.
Also, the surface sizing agent used in the size press liquid is conventionally known in the papermaking field. Examples of surface sizing agents include starch-based sizing agents, cellulose-based sizing agents, polyvinyl alcohol-based sizing agents, styrene-acrylic sizing agents, olefin-based sizing agents, styrene-maleic acid-based sizing agents, and acrylamide-based sizing agents. can be done.

A size press is a sizing process using a size press apparatus conventionally known in the papermaking field. The size press equipment includes, for example, an inclined size press, a horizontal size press, a rod metering size press, a roll metering size press and a blade metering size press as film transfer methods, and a shim sizer, an optimizer and a rod metering size press as rod metering size presses. A speed sizer, a gate roll coater as a roll metering size press, a bill blade coater, a twin blade coater, a velvapa coater, a tab size press, a calendar size press, and the like can be mentioned.

The barrier layer contains an inorganic layered mineral and polyhydroxyurethane. The barrier layer can obtain excellent heat deformation resistance and oxygen barrier properties by blending the inorganic layered mineral with the barrier layer made of polyhydroxyurethane. In some embodiments, the content of the inorganic layered mineral in the barrier layer is 50 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the polyhydroxyurethane in the barrier layer. The reason for this is that the heat deformation resistance and oxygen barrier properties are improved.

Inorganic layered minerals are tabular inorganic pigments obtained from natural or synthetic minerals having a layered skeleton in which crystal planes grown in the plane direction are layered and have cleavability. Examples of inorganic layered minerals include kaolin, mica, pyrophyllite, talc, bentonite, montmorillonite, smectite, vermiculite, chlorite, septe chlorite, serpentine, stilpnomelane and alumina. Examples of inorganic pigments that do not correspond to inorganic layered minerals include those conventionally known in the field of coated paper, such as heavy calcium carbonate, light calcium carbonate and silica.

In some embodiments, the barrier layer includes at least mica as the inorganic layered mineral. In at least one embodiment, the barrier layer has a mica content of 10% by mass or more with respect to the inorganic pigment including the inorganic layered mineral in the barrier layer. The reason for these is that the heat distortion resistance and oxygen barrier properties are improved. Although the reason for exhibiting such an effect is unknown, the present inventors speculate as follows. Since mica has thermal stability and heat resistance, it has an effect on the thermal deformation resistance of the barrier layer. In addition, since mica crystals have film-like elasticity, polyhydroxyurethane easily penetrates between the layered particles of mica, and as a result, a layer having excellent oxygen barrier properties is formed.

Mica, also called mica, is a kind of mineral containing silicon as a main component, and there are natural products and synthetic products. Mica is produced by industrially refining and processing natural mica raw ore, and is produced through processes such as pulverization, washing, iron removal and classification. Mica is produced by heating and fusing raw materials such as silica sand, magnesium oxide, aluminum oxide, potassium silicofluoride, and sodium silicofluoride.
In some embodiments, the mica has an aspect ratio of 100 or greater. In at least one embodiment, the mica has an aspect ratio of 680 or greater. These reasons are because the oxygen barrier properties are improved. There is no particular upper limit to the aspect ratio of mica. In some embodiments, the mica has an aspect ratio of 2000 or less. The reason for this is that it is superior in terms of material cost and availability. Mica is commercially available from, for example, Topy Industries, Yamaguchi Mica, and the like.

In some embodiments, the packaging paper has a paper substrate, a barrier layer on at least one side of said paper substrate, and a heat seal layer on the outside of said barrier layer with respect to said paper substrate. and the barrier layer contains mica and polyhydroxyurethane. In at least one embodiment, the packaging paper has a paper substrate, a barrier layer on at least one side of the paper substrate, and a heat seal layer on the outside of the barrier layer relative to the paper substrate. and the barrier layer contains mica and polyhydroxyurethane, and the mica has an aspect ratio of 100 or more.

The aspect ratio can be calculated, for example, from the volume-based average particle diameter and the number average particle thickness. The aspect ratio is a value calculated by the following formula.
[Aspect ratio] = [volume-based average particle size (μm)] / [number average thickness (μm)]
Here, the "volume-based average particle size" is obtained by, for example, weighing 100 mg of the inorganic layered mineral, dispersing it in water, and using a laser diffraction/scattering particle size distribution measuring device (for example, laser diffraction/scattering by Nikkiso Co., Ltd.). It is determined using a type particle size distribution analyzer (Microtrac MT3300EXII). The "number-average thickness" is obtained by, for example, measuring the thickness of 10 randomly selected images of the inorganic layered mineral observed at a magnification of 2000 using a scanning electron microscope, and averaging the thicknesses.

In some embodiments, the barrier layer contains kaolin as an inorganic layered mineral other than mica. The reason for this is that the oxygen barrier properties may be improved.
Kaolin is a kind of inorganic pigment. Kaolin is produced by industrially refining and processing naturally occurring kaolin ore, and is produced through processes such as pulverization, washing, iron removal and classification, for example. In addition, highly processable kaolin, such as delaminated kaolin, which is made into a thin plate by applying shear force to improve the aspect ratio, engineered kaolin, which is adjusted to have a sharp particle size distribution, and calcined kaolin, which has increased cohesion. is also included.
In some embodiments, the kaolin has an aspect ratio of 15 or greater. The reason for this is that the oxygen barrier properties are improved. The upper limit of the aspect ratio of kaolin is not particularly limited. In some embodiments, the kaolin aspect ratio is 100 or less. The reason for this is the superiority in terms of material cost and availability. Kaolin is commercially available from, for example, BASF, Hyogo Clay, KaMinLLC and Imerys.

Polyhydroxyurethane refers to conventionally known urethane-based resins having hydroxyl groups in side chains. Polyhydroxyurethane is, for example, a urethane resin as described in JP-A-2021-146519, JP-A-2018-070841 and JP-A-2012-172144. In some embodiments, the polyhydroxyurethane has an acid value of 5 mg KOH/g or more and 100 mg KOH/g or less. The reason for this is that the oxygen barrier properties are improved. The acid value is measured by a titration method in accordance with JIS K1557-5:2007 "Plastics - Polyurethane raw material polyol test method - Part 5: Determination of color number, viscosity, acid value and pH" per 1 g of resin. It is a value representing the content of each functional group in mg equivalent of KOH.
Hydroxypolyurethanes and polyurethanes are commercially available from, for example, Mitsui Chemicals, DIC, Dainichiseika Kogyo and Toyochem.

The barrier layer can contain conventionally known various additives as needed in addition to the inorganic layered mineral and polyhydroxyurethane. Additives include, for example, inorganic pigments other than inorganic layered minerals, organic pigments, water-soluble polymers such as polyvinyl alcohol, butadiene-based copolymer resins, vinyl acetate-based copolymer resins, acrylic resins, polyester-based resins, and polyamide-based resins. various resins other than polyhydroxyurethane such as polysaccharides, polysaccharides such as starches and celluloses, surfactants, dispersants, thickeners, water retention agents, antifoaming agents, and water resistance agents.

In some embodiments, the coating weight of the barrier layer is 8 g/m ² or more and 28 g/m ² or less as dry solids per side of the paper substrate. The reason for this is that the oxygen barrier property is improved.

The method of providing the barrier layer on the paper substrate is not particularly limited. Examples of the method of providing a barrier layer on a paper base include a method of applying and drying a barrier layer coating liquid using a conventionally known coating apparatus and drying apparatus in the field of paper manufacturing. Examples of coating equipment include film press coaters, rod coaters, air knife coaters, rod blade coaters, bar coaters, blade coaters, gravure coaters, curtain coaters, E bar coaters and film transfer coaters. Examples of drying equipment include hot air dryers such as straight tunnel dryers, arch dryers, air loop dryers, sine curve air float dryers, infrared heating dryers, microwave dryers, and various other drying equipment. can be done. In a trial production in a laboratory, a method of applying a barrier layer coating solution to a paper base material with a wire bar for manual coating and drying with a simple hot air dryer can be adopted.
In the method of providing the heat seal layer on the barrier layer, the heat seal layer coating liquid is applied to the barrier layer using the same coating device and drying device as in the method of providing the barrier layer on the paper substrate. The method of processing and drying can be mentioned.

Each layer obtained by the barrier layer coating liquid containing an inorganic layered mineral and polyhydroxyurethane and the heat seal layer coating liquid containing a resin having heat-sealing properties contains an inorganic layered mineral and polyhydroxyurethane. and a resin having heat-sealing properties.

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. Here, "parts by mass" and "% by mass" respectively represent "parts by mass" and "% by mass" of the amount of dry solids and the amount of substantial components. The coating amount of the coating layer represents the dry solid content.

<Paper substrate>
The following stock was prepared.
LBKP (freeness 350 to 480 mlcsf) 50 parts by mass NBKP (freeness 350 to 480 mlcsf) 50 parts by mass Aluminum sulfate 1 part by mass Rosin-based sizing agent (CC1404, Seiko PMC) 0.4 parts by mass Paper strength agent 0.4 parts by mass 9 parts by mass

The stock having the above composition was made into paper by a Fourdrinier paper machine, and oxidized starch as a surface sizing agent was applied to each side by a size press in an amount of 1 g/m ² to obtain a base paper having a basis weight of 45 g/m ² . This was calendered using a machine calender at a temperature of 60° C. and a processing speed of 500 m/min to obtain a paper substrate. The ash content of the paper substrate was 1.5% by mass.

<Barrier layer coating liquid>
Using water as a medium, the following barrier layer coating solution was prepared.
Pigment types and parts by mass are listed in Table 1 Resin types are listed in Table 1/70 parts by mass

<Heat seal layer coating liquid>
Using water as a medium, the following heat seal layer coating solution was prepared.
Resin types are listed in Table 1/100 parts by mass

Each material appearing in Table 1 is as follows.
Kaolin: Imerys Contour Extreme, aspect ratio 35.
Mica 1: Topy Industries PDM-40L, aspect ratio 80.
Mica 2: Yamaguchi Mica A-41S, aspect ratio 100.
Mica 3: Yamaguchi Mica TM-20, aspect ratio 140;
Mica 4: Topy Industries NTO-8, aspect ratio 680.
Mica 5: Topy Industries DMA-350, aspect ratio 1000.
Mica 6: Topy Industries NTS-10, aspect ratio 1500.
Inorganic pigment: Carvirax (registered trademark) ground calcium carbonate from Imerys.
Resin 1: Polyhydroxyurethane,
Mitsui Chemicals Takelac (registered trademark) WPB-341.
Resin 2: low density polyethylene resin,
Mitsui Chemicals Chemipearl (registered trademark) M200.
Resin 3: Methyl methacrylate butyl acrylate copolymer resin.
Resin 4: Ethylene-acrylic acid-based copolymer resin.

<Barrier layer>
The barrier layer coating solution was applied to one side of the paper substrate with an air knife coater and dried with a hot air dryer. The coater conditions were adjusted so that the coating amount of the barrier layer was 15 g/m ² .

<Heat seal layer>
The heat seal layer coating solution was applied to the obtained barrier layer with a rod coater and dried with a hot air dryer. The coater conditions were adjusted so that the coating amount of the heat seal layer was 10 g/m ² .

<Wrapping paper>
As described above, the wrapping paper was prepared by providing the barrier layer on the paper substrate and the heat seal layer on the barrier layer. However, in Comparative Example 2, the heat-seal layer coating solution was applied and dried to the paper substrate without applying and drying the barrier layer.

<Oxygen barrier property>
Evaluation of oxygen barrier property is performed according to ISO15105-2:2003 "Plastics-Film and sheeting-Determination of gas-transmission rate-Part2: Equal-pressure method" (JIS K7126-2:2006 "Plastics-Films and sheets- Gas transmission degrees Test method-Part 2: Isobaric method") from the measurement results of gas permeability. Measurements were taken with the side having the barrier layer and heat seal layer facing outward. Oxygen gas was used as the measuring gas for the gas permeability. The temperature and humidity conditions were 23±0.5° C. and 85±2% relative humidity. In the present invention, if the packaging paper is evaluated as A, B or C, it is considered to be excellent in oxygen barrier properties.
A: Gas permeability is 9 ml/m ² ·day·atm or less.
B: The gas permeability is inferior to the above A, 18 ml/m ² ·day·atm or less.
C: The gas permeability is inferior to the above B, 40 ml/m ² ·day·atm or less.
D: The gas permeability is inferior to the above C, 80 ml/m ² ·day·atm or less.
E: Gas permeability exceeds 80 ml/m ² ·day·atm.

<Heat sealability>
Using two sheets of wrapping paper having the same structure, the sides having the heat-seal layer of the wrapping paper were opposed to each other and heat-sealed with a heat sealer under the conditions of a pressure of 0.5 MPa, 130° C., and 1 second.
Cut out the heat-sealed packaging paper to a width of 15 mm, leave it at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours, and then use a tensile tester to measure the peel strength at the heat-sealed portion at a tensile speed of 300 mm / min and a tensile angle of 180 degrees. The heat-sealability was evaluated by measuring. The measurement was performed with 5 samples for each wrapping paper, and the average value of the 5 copies was taken. From the measured values, the heat sealability was evaluated according to the following criteria. In the present invention, if the packaging paper is rated A, B or C, it is assumed to have heat sealability.
A: The value is 6N/15mm or more.
B: The value is 4N/15mm or more and less than 6N/15mm.
C: The value is 2 N/15 mm or more and less than 4 N/15 mm.
D: The value is less than 2N/15mm.

<Heat deformation resistance>
The heat deformation resistance was evaluated by observing the appearance of the heat-sealed portion of a flat bag in which the wrapping paper was horizontally (stitched with palms together) and vertically (stitched with an envelope) sealed. The heat-sealing conditions were the same as those for the <heat-sealing property> evaluation. The heat sealing was carried out on 20 samples of each wrapping paper. In the present invention, if the packaging paper is rated A, B or C, it is considered to be excellent in heat deformation resistance.
A: Almost no wrinkles, misalignments, and twists are observed in all 20 copies.
B: Almost no wrinkles are observed in all 20 copies.
And a slight shift and/or twist is observed in the 1st to 3rd parts.
C: Almost no wrinkles are observed in all 20 copies.
And 4 or more parts are slightly misaligned and/or twisted.
D: Almost no wrinkles are observed in all 20 copies.
And clear shift and/or twist is observed in the 1st and 2nd parts.
E: Wrinkles are observed in one or more copies.
And/or clear misalignment and/or twist is observed in 3 or more copies.

Table 1 shows the evaluation results.

From Table 1, it can be seen that Examples 1 to 13, which correspond to the present invention, have heat-sealing properties, are excellent in heat deformation resistance despite being a barrier layer containing polyurethane as the main component of the resin, and are excellent in oxygen barrier properties. I understand. On the other hand, it can be seen that Comparative Examples 1 to 3, which do not satisfy the constitution of the present invention, are packaging papers that cannot satisfy at least one of the effects of the present invention.

Mainly from the comparison with Examples 1 and 12, it can be seen that when the inorganic layered mineral of the barrier layer is mica, the thermal deformation resistance and oxygen barrier properties of the packaging paper are improved.
Mainly from the comparison between Examples 2 to 7, it can be seen that when the aspect ratio of mica is 100 or more, the packaging paper has improved oxygen barrier properties.

Claims (3)

a paper substrate; a barrier layer on at least one side of the paper substrate; A wrapping paper containing hydroxyurethane. The wrapping paper according to claim 1, wherein said inorganic layered mineral comprises mica. 3. The wrapping paper according to claim 2, wherein said mica has an aspect ratio of 100 or more.