Packaging materials

Abstract

To provide a packaging material having adhesivity of a face to be heat sealed, heat sealability and anti-blocking property.SOLUTION: A packaging material has a paper holding body and one or two or more coating layers on one surface of the paper holding body. The paper holding body has density of 0.83 g / cm3 or more and 1.03 g / cm3 or less, and 2.3 mass% or less of ash. In the packaging material, the outermost coating layer with the paper holding body as a reference in the coating layer, contains at least ionomer resin of ethylene unsaturated carboxylic acid copolymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a heat-sealable packaging material made of a paper support, and more particularly to a packaging material used for secondary packaging in the form of a bag. [Background technology]

[0002] Many confectionery and other food products displayed in retail stores are packaged in a way that consists of a primary package containing the food and a secondary package containing one or more of the primary packages. Typically, primary packaging exists to protect food, and secondary packaging exists to protect the primary packaging. Secondary packaging comes in two forms: bags and boxes. Bag-type secondary packaging is generally created by covering the primary packaging with packaging material and heat-sealing the edges of the packaging material. Therefore, the packaging material used for bag-type secondary packaging must be suitable for heat sealing.

[0003] Packaging materials suitable for heat sealing are well known. For example, packaging paper having at least one heat-sealable layer on at least one surface of a paper substrate, wherein the heat-sealable layer contains an ionomer, and the dry coating amount of the heat-sealable layer is 2 to 10 g / m² for the entire layer. 2 Packaging paper of this type is publicly known (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-117311 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In recent years, due to environmental pollution problems caused by microplastics, plastic films have been increasingly phased out in the field of packaging materials. Paper supports are a promising alternative to plastic films. Patent document 1 also discloses packaging paper that replaces plastic with paper, aiming to reduce the amount of plastic used. However, paper supports lack the smoothness of plastic films. Therefore, in order to prevent gaps from occurring at the heat-sealed areas or to ensure that the heat-sealed areas are uniform in strength, the packaging material needs to have good adhesion to the heat-sealed surfaces. On the other hand, improving the adhesion of the heat-sealed surfaces in packaging materials can cause blocking between the packaging materials.

[0006] A unique challenge with secondary packaging is the heat problem during heat sealing. Specifically, when heat-sealing packaging materials to form a bag, the heat generated during the heat sealing process can damage the food inside the primary packaging. For example, if the food is chocolate, it may melt during heat sealing. When handling food, heat sealing must be achieved at a relatively low temperature and for a short time.

[0007] Therefore, the object of the present invention is to provide a packaging material having the following qualities. (1) The surfaces to be heat-sealed must have good adhesion (adhesion). (2) The ability to heat seal at a relatively low temperature and in a short time (heat seal suitability). (3) Ability to suppress blocking between packaging materials (blocking resistance). [Means for solving the problem]

[0008] As a result of diligent research, the inventors of this invention have determined that the objective of this invention is achieved as follows.

[0009] [1] A paper support having one or more coating layers on one side of the paper support, wherein the paper support has a density of 0.83 g / cm³ 3 More than 1.03g / cm 3A packaging material having the following properties and an ash content of 2.3% by mass or less, wherein the outermost coating layer, relative to the paper support, contains at least an ionomer resin of an ethylene unsaturated carboxylic acid copolymer.

[0010] [2] The packaging material according to [1] above, wherein the outermost coating layer is a layer that substantially does not contain inorganic pigments. [Effects of the Invention]

[0011] The present invention provides a packaging material having adhesion, heat sealability, and blocking resistance. [Modes for carrying out the invention]

[0012] The packaging material comprises a paper support and one or more coating layers on one side of the paper support. In the coating layers, the outermost coating layer relative to the paper support is called the outermost coating layer. If there is only one coating layer, this coating layer is the outermost coating layer. If there are two or more coating layers, the coating layers between the base paper and the outermost coating layer are not particularly limited. In some embodiments, the coating layers between the base paper and the outermost coating layer are provided to impart various functions to the packaging material as needed. Examples of coating layers include a gas barrier layer containing a gas barrier agent, a water vapor barrier layer containing a water vapor barrier agent, an oil barrier layer containing an oil resistant agent, and an insulating layer containing an insulating material. In some embodiments, in the case of packaging materials used in secondary packaging, there is only one coating layer, including the outermost coating layer. That is, there is only one coating layer. The reason for this is that it is cost-effective to manufacture as a packaging material used in secondary packaging. Furthermore, the coating layer may be present on one or both sides of the paper support. In some embodiments, the packaging material has the outermost coating layer on only one side of the paper support. In some embodiments, the packaging material having the outermost coating layer on only one side of the paper support has a conventionally known printing coating layer or backcoat layer on the opposite side of the paper support for the purpose of improving printability or dimensional stability. As a packaging material used in a secondary packaging body, the side of the packaging material facing the contents is the side of the packaging material that has the outermost coating layer.

[0013] The paper support is a base paper produced by conventionally known papermaking methods under acidic, neutral, or alkaline conditions, using a paper stock to which various additives such as fillers, internal sizing agents, fixatives, yield agents, and paper strength agents are added as needed to a slurry consisting of wood pulp and / or non-wood pulp; a base paper obtained by calendering the said base paper; fine paper obtained by sizing the said base paper with a sizing liquid containing a surface sizing agent; or fine paper obtained by calendering the said fine paper.

[0014] In the above paper material, as other additives, one or more selected from pigment dispersants, binders, thickeners, fluidity improvers, bulking agents, defoamers, antifoaming agents, mold release agents, foaming agents, penetrants, coloring dyes, coloring pigments, fluorescent brighteners, ultraviolet absorbers, antioxidants, preservatives, mildew-proof agents, water resistance agents, etc. can be appropriately added within the range that does not impair the desired effects of the present invention.

[0015] Calendering is a process of averaging smoothness and thickness by passing paper between rolls. Examples of calendering devices include machine calenders, soft nip calenders, super calenders, multi-stage calenders, multi-nip calenders, etc.

[0016] Size press is a process of imparting water resistance to the surface of paper. The size press is performed using a size press device conventionally known in the paper manufacturing field. Examples of size press devices include in-line size presses, horizontal size presses, rod metering size presses as film transfer, roll metering size presses, blade metering size presses, shim sizars, opti sizars, and speed sizars as rod metering size presses, gate roll coaters as roll metering size presses, bill blade coaters, twin blade coaters, bell bapa coaters, tab size presses, and calendar size presses, etc.

[0017] Wood pulp is well-known in the paper-making field. Wood pulp includes, for example, chemical pulps such as LBKP (Leaf Bleached Kraft Pulp) and NBKP (Needle Bleached Kraft Pulp), mechanical pulps such as 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 pulps such as DIP (DeInked Pulp). Non-wood pulp is pulp made from non-wood fibers that are well-known in the paper-making field. Raw materials of non-wood fibers include, for example, ligneous bast fibers such as kozo, mitsumata and ganpi, herbaceous bast fibers such as flax, hemp and kenaf, leaf fibers such as manila hemp, abaca and sisal hemp, gramineous plants such as rice straw, wheat straw, sugarcane bagasse, bamboo and esparto, and seed hairs such as cotton and linter. 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.

[0018] In some embodiments, the base paper for the paper support contains at least NBKP and LBKP as pulp. In some embodiments, in the base paper for the paper support, the total content of NBKP and LBKP in the base paper is 90% by mass or more based on the pulp in the base paper. This is because the paper strength of the base paper is improved. Since the packaging material used for the secondary package includes the purpose of protecting the primary package during transportation, paper strength is important.

[0019] The filler is an inorganic pigment conventionally known in the papermaking field. Examples of inorganic pigments include 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, alumina hydrate, aluminum hydroxide, lithopone, zeolite, magnesium carbonate, and magnesium hydroxide. The filler is one or more selected from the group consisting of the above inorganic pigments. In some embodiments, the base paper for the paper support contains substantially no filler. This is because it improves the paper strength of the base paper. "Substantially no filler" means that if the amount of filler does not worsen the paper strength of the base paper, it is considered to contain no filler. In at least one implementation, the filler content in the base paper is 3% by mass or less relative to the pulp in the base paper. This is because the paper strength does not worsen if the filler content is 3% by mass or less relative to the pulp.

[0020] The sizing agent is a sizing agent that has been conventionally known in the papermaking field. Examples of internal sizing agents added to paper stock include rosin-based sizing agents for acidic paper, and alkenyl succinic anhydride, alkyl ketene dimers, neutral rosin-based sizing agents, and cationic styrene-acrylic sizing agents for neutral paper. Furthermore, the surface sizing agents used in the sizing press fluid are those 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. In some embodiments, the paper support is fine paper obtained by sizing the base paper with a sizing liquid containing a surface sizing agent. This is because it improves adhesion and heat sealability.

[0021] The fixative is a conventionally known fixative in the papermaking field. The fixative improves the fixation of the sizing agent. Examples of fixatives include inorganic salts such as aluminum sulfate.

[0022] Yield agents are conventionally known yield agents in the papermaking field. Yield agents improve the yield of various additives added to the pulp. Examples of yield agents include organic polymer electrolytes such as polyacrylamide, polyamides and polyethyleneimine, and polyethylene oxide.

[0023] Paper strength agents are those conventionally known in the papermaking field. Paper strength agents improve the paper strength of the base paper. Examples of paper strength agents include cationized starch, dialdehyde starch, plant-based gum, urea-formaldehyde resin, polyamide-polyamine-epichlorohydrin polycondensate, and glyoxal-modified polyacrylamide.

[0024] The paper support has a density of 0.83 g / cm³. 3 More than 1.03g / cm 3The following applies. The density of the paper support affects the smoothness of the paper support and thus influences the formation of the coating layer onto which the coating liquid is applied. Higher density increases smoothness, while lower density decreases smoothness. On the other hand, excessively high density of the paper support negatively affects blocking resistance. The density is measured according to ISO 534:2011 "Paper and board - Determination of thickness, density and specific volume". The density of the paper support is a parameter conventionally known in the papermaking field and can be adjusted by, for example, papermaking conditions such as press part conditions, pulp type and degree of beating, filler type and content, and the presence and condition of calendering. Generally, actions such as increasing the nip pressure of the press part, increasing pulp beating, adding fillers, performing size pressing, and calendering increase the density of the paper support. In some embodiments, the density of the paper support is adjusted by size pressing and calendering. This is because it improves the smoothness of the paper support, which has a positive effect on adhesion and heat sealability.

[0025] The paper support has an ash content of 2.3% by mass or less. The ash content of the paper support indicates the content of metal components, etc., derived from fillers and inorganic salts contained in the paper support. The ash content of the paper support is related to the permeability of the paper support and therefore affects the formation of the coating layer on which the coating liquid is applied to the paper support. Higher ash content increases permeability, while lower ash content decreases permeability. The ash content is a value measured in accordance with ISO 1762:2019 "Paper, board, pulps and cellulose nanomaterials - Determination of residue (ash content) on ignition at 525 degree C". The ash content of the paper support is a parameter conventionally known in the papermaking field and can be adjusted by, for example, the type and content of the fixative, which is a filler and / or inorganic salt. In some embodiments, the base paper for the paper support contains substantially no filler. This is because it is easy to adjust the ash content to 2.3% by mass or less.

[0026] The paper support has a density of 0.83 g / cm³. 3 More than 1.03g / cm 3 The density and ash content are 2.3% by mass or less. Paper supports with density and ash content within the above range have appropriate smoothness and permeability. The packaging material exhibits adhesion, heat sealability, and blocking resistance through the synergistic effect of the paper support having the above physical properties and the outermost coating layer described below. If the density or ash content of the packaging material falls outside the above range, at least one of the effects of the present invention cannot be satisfied.

[0027] In some embodiments, the paper support has an opacity of 70% to 85%. This is because it improves adhesion, heat sealability, and / or blocking resistance. The opacity is measured according to ISO 2471:2008 "Paper and board - Determination of opacity (paper backing) - Difuse reflectance method". The opacity of a paper support is a parameter conventionally known in the papermaking field and can be adjusted by, for example, the type and degree of pulp beating, the type and content of fillers, and the presence and condition of calendering. Generally, actions such as reducing the pulp beating, adding fillers, and performing size pressing increase the opacity of the paper support, while calendering decreases it. The opacity of a paper support indirectly represents the void state of the paper support. If voids that exhibit light scattering exist in the paper support, the opacity of the paper support increases. On the other hand, if the voids in the paper support that exhibit light scattering are crushed or filled, the opacity of the paper support decreases. Also, if the thickness of the paper support decreases, the opacity of the paper support decreases.

[0028] The outermost coating layer contains an ionomer resin of an ethylene unsaturated carboxylic acid copolymer. The ionomer resin of an ethylene unsaturated carboxylic acid copolymer is a compound represented by the following general formula.

[0029] [ka]

[0030] x, y, and z represent the composition ratios of the respective monomers in the resin. R1 and R2 represent a hydrogen atom or an alkyl group. In some embodiments, the alkyl group is an alkyl group having 1 to 4 carbon atoms. M represents a metal that forms a salt with a carboxyl group. The M is, for example, sodium, potassium, calcium, magnesium, zinc, etc. In some embodiments, the M is one or more selected from the group consisting of alkali metals and alkaline earth metals. The ionomer resin of the ethylene unsaturated carboxylic acid copolymer is commercially available from, for example, Mitsui Chemicals, Inc., Mitsui-Dow Polychemicals Co., Ltd., and Marubeni Chemical Co., Ltd.

[0031] The ionomer resin of the ethylene unsaturated carboxylic acid copolymer obtains adhesiveness due to the diffusion of the cross-linking bond of metal ions by heat, and as a result, it has excellent heat-sealing suitability. In addition, the inventors presume that the ionomer resin of the ethylene unsaturated carboxylic acid copolymer forms a microcrystalline structure with M as the core in the outermost coating layer formed by coating and drying, and the microcrystalline structure contributes to blocking resistance. And the inventors believe that the microcrystalline structure can be formed well and the blocking resistance can be exhibited in a paper support having a density of 0.83 g / cm 3 or more and 1.03 g / cm 3 or less and an ash content of 2.3 mass% or less.

[0032] The outermost coating layer may contain conventionally known resins other than ionomer resins of ethylene unsaturated carboxylic acid copolymers. Examples of resins include conjugated diene resins such as styrene-butadiene copolymer resins and acrylonitrile-butadiene copolymer resins, acrylic resins such as polymer resins of acrylic acid esters or methacrylic acid esters or methacrylic acid ester-butadiene copolymer resins, vinyl resins such as vinyl chloride resins, vinylidene chloride resins, ethylene vinyl acetate copolymer resins and vinyl chloride vinyl acetate copolymer resins, thermosetting synthetic resins such as polyurethane resins, alkyd resins, polyester resins, melamine resins and urea resins, starches such as natural rubber, starch, various modified starches and various modified starches, celluloses such as carboxymethylcellulose and hydroxyethylcellulose, natural polymer resins or derivatives thereof such as casein, gelatin and soy protein, polyvinylpyrrolidone, polyvinyl alcohol and modified polyvinyl alcohol, polypropylene glycol, and polyethylene glycol. In some embodiments, the outermost coating layer may contain various conventionally known additives in addition to the ionomer resin of the ethylene unsaturated carboxylic acid copolymer. Examples of additives include viscosity modifiers, defoamers, surfactants, leveling agents, and colorants. In some embodiments, the outermost coating layer contains 90% by mass or more of an ionomer resin of an ethylene unsaturated carboxylic acid copolymer relative to the dry solid content of the outermost coating layer. This is because it improves adhesion, heat sealability, and / or blocking resistance.

[0033] In some embodiments, the outermost coating layer is substantially free of inorganic pigments. This is because it improves heat-sealability. Here, "substantially free" refers to a range where the inorganic pigment content is 2% by mass or less relative to the dry solids content of the outermost coating layer. The inorganic pigments are those conventionally known in the papermaking field and are similar to the inorganic pigments exemplified in the fillers above.

[0034] A coating layer, including the outermost coating layer, can be provided by applying and drying a coating liquid to a paper support. Methods for coating and drying include, for example, applying and drying the coating liquid using coating and drying equipment conventionally known in the field of coated paper. Examples of coating equipment include film press 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 various drying devices such as straight tunnel dryers, arch dryers, air loop dryers, sine curve air float dryers, infrared heating dryers, and microwave dryers.

[0035] In some embodiments, the amount of ionomer resin of ethylene unsaturated carboxylic acid copolymer applied in the outermost coating layer is 3 g / m² per side of the paper support, based on dry solids. 2 That concludes the explanation. The reason for this is that adhesion and heat sealability are improved. There is no particular upper limit on the coating amount. In some embodiments, based on the relationship between adhesion, heat sealability and material cost, the upper limit of the coating amount is 8 g / m². 2 The following applies: [Examples]

[0036] 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 "mass%" represent "parts by mass" and "mass%" of the dry solids content and substantial component content, respectively. The coating amount of each layer represents the dry solids content.

[0037] <Paper support> The following paper pulp was prepared. LBKP (freeness 630mlcsf) 500 parts by mass NBKP (freeness 470mlcsf) 500 parts by mass The quantities of aluminum sulfate are listed in Table 1. The quantity of light calcium carbonate is listed in Table 1. 12 parts by mass of cationized starch Rosin-based sizing agent 5 parts by mass Polyacrylamide-based yield agent: 0.1 parts by mass The pulp mixture described above was produced using a long-screen paper machine, and the basis weight was 54 g / m² while adjusting the press part conditions of the paper machine. 2 A base paper was obtained. A sizing press was then performed using oxidized starch as a surface sizing agent. The amount of oxidized starch applied was 0.8 g / m². 2 ~1.8g / m 2 The parameters were adjusted within the specified range. Next, a paper support was obtained by performing a supercalendering process while adjusting the conditions. The density, ash content, and opacity of the obtained paper support are shown in Table 1.

[0038] <Coating liquid for the outermost coating layer> A coating solution for the outermost coating layer containing the following was prepared using water as a medium. Resin 100 parts by mass The quantity of calcium carbonate is listed in Table 1. The solid content concentration of the coating solution for the coating layer was adjusted to 28% by mass. The resins are listed in Table 1.

[0039] The resins listed in Table 1 are as follows: Resin 1: Ionomer resin of ethylene unsaturated carboxylic acid copolymer (Mitsui Chemicals, Inc., ChemiPearl® S100, average particle size 0.1 μm by microtrac method) Resin 2: Ionomer resin of ethylene unsaturated carboxylic acid copolymer (Maruyoshi Chemical Co., Ltd., MYE-30MAZ, average particle size 0.3 μm by microtrac method) Resin 3: Ionomer resin of ethylene unsaturated carboxylic acid copolymer (Mitsui Chemicals, ChemiPearl S300, average particle size 0.5 μm by microtrac method) Resin 4: Ionomer resin of ethylene unsaturated carboxylic acid copolymer (Mitsui Chemicals, ChemiPearl S500, average particle size 0.7 μm by microtrac method) Resin 5: Polyethylene resin (Sunopco, SN Coat 287) Resin 6: Ethylene methyl methacrylate copolymer resin (Sumitomo Chemical Co., Ltd., Aclift® WK307)

[0040] <Packaging materials> A packaging material with an outermost coating layer was obtained by applying the coating solution for the outermost coating layer to one side of a paper support using an air knife coater and drying it in a hot air dryer. The amount of coating is shown in Table 1.

[0041] [Table 1]

[0042] The following evaluations were performed on the obtained packaging materials.

[0043] <Adhesion> Using packaging material, the surfaces with the outermost coating layer are placed facing each other and a heat sealer is applied at a pressure of 2.0 kg / cm². 2 The product was heat-sealed at 130°C for 1 second. Ten pieces of heat-sealed packaging material were cut to a width of 15 mm and left to stand for 24 hours at 20°C and 65% RH. The edges of the packaging material were then gently pulled several times by hand to release the heat seals, and the heat-sealed areas were observed. The adhesion was evaluated based on the observation results according to the following criteria. In this invention, packaging material is considered to have good adhesion on the heat-sealed surface if it receives an evaluation of A, B, or C. A: There are no gaps in the heat-sealed area. Furthermore, the strength is uniform across the 10 heat-sealed points. B: There are no gaps in the heat-sealed area. Furthermore, there is a very slight unevenness in strength at 10 heat-sealed points. C: There are no gaps in the heat-sealed area. Furthermore, there is slight unevenness in strength at 10 heat-sealed points. D: There is a gap in the heat-sealed area. And / or the strength is uneven at 10 heat-sealed points.

[0044] <Suitability for heat sealing> Using packaging material, the surfaces with the outermost coating layer are placed facing each other and a heat sealer is applied at a pressure of 2.0 kg / cm².2 The heat seal was applied using relatively low temperatures of 90°C for 1 second. Heat-sealable packaging material was cut into 15 mm wide strips and left to stand at 20°C and 65% RH for 24 hours. The peel strength of the heat-sealed area was then measured using a tensile testing machine at a tensile speed of 200 mm / min and a tensile angle of 180 degrees to evaluate its heat-sealability. Measurements were performed on 5 samples, and the average value of these 5 samples was used. Based on the measured values, heat-sealability was evaluated according to the following criteria. In this invention, a packaging material is considered to have heat-sealability if it receives an evaluation of A or B. A: The value is 16N / 15mm or higher. B: Value is 10N / 15mm or more and less than 16N / 15mm. C: Value is 4N / 15mm or greater and less than 10N / 15mm. D: Value less than 4N / 15mm.

[0045] <Blocking resistance> The packaging material was wound into a roll (500 m in length) on a 150 mm diameter paper tube with the image recording layer facing outwards. The roll was left to stand for 24 hours at 20°C and 65% RH using two methods: direct placement and suspension. After standing, the packaging material was unwound (unwinder). At this time, the blocking state of the packaging material was visually observed. Based on the observation results, the blocking resistance was evaluated according to the following criteria. In this invention, a packaging material is considered to have blocking resistance if it receives an evaluation of A or B. A: Blocking is not observed using either direct placement or suspension. B: Very weak blocking is observed when placed directly on the surface. Blocking is not permitted using the suspended method. C: Weak blocking is observed when using the direct placement method. Blocking is not permitted using the suspended method. D: Blocking is permitted using a suspended method.

[0046] The evaluation results are shown in Table 1.

[0047] Table 1 shows that Examples 1 to 15, which correspond to the present invention, are packaging materials that have adhesion, heat sealability, and blocking resistance. On the other hand, Comparative Examples 1 to 6, which do not satisfy the configuration of the present invention, are packaging materials that cannot satisfy at least one of adhesion, heat sealability, and blocking resistance. From a comparison mainly between Examples 3, 14, and 15, it can be seen that the heat-sealability of the packaging material improves when the outermost coating layer substantially does not contain inorganic pigments. From a comparison mainly between Examples 3, 5, 6, 7, and 8 and Examples 9 and 10, it can be seen that when the opacity of the paper support is between 70% and 85%, the packaging material exhibits improved adhesion, heat sealability, and / or blocking resistance.

[0048] With regard to the embodiments of the present invention described above, the following additional information is disclosed.

[0049] <1> The device comprises a paper support and one or more coating layers on one side of the paper support, wherein the paper support has a density of 0.83 g / cm³. 3 More than 1.03g / cm 3 A packaging material having the following properties and an ash content of 2.3% by mass or less, wherein the outermost coating layer, relative to the paper support, contains at least an ionomer resin of an ethylene unsaturated carboxylic acid copolymer.

[0050] <2> The outermost coating layer is a layer that substantially does not contain inorganic pigments. <1> The packaging materials listed.

[0051] <3> The above coating layer, including the outermost coating layer, is a single layer. <1> The packaging materials listed.

[0052] <4> The outermost coating layer is a layer that substantially does not contain inorganic pigments, and the coating layer, including the outermost coating layer, is a single layer. <1> The packaging materials listed.

[0053] <5> The opacity of the above paper support is 70% or more and 85% or less. <1> or <4> The packaging materials listed.

Claims

1. The device comprises a paper support and one or more coating layers on one side of the paper support, wherein the paper support has a density of 0.83 g / cm³. ３ 1.03g / cm or more ３ A packaging material having the following characteristics and an ash content of 2.3% by mass or less, wherein the outermost coating layer, located on the paper support, contains at least an ionomer resin of an ethylene unsaturated carboxylic acid copolymer, and the opacity of the paper support is 70% or more and 85% or less.

2. The packaging material according to claim 1, wherein the inorganic pigment content is 2% by mass or less relative to the dry solid content of the outermost coating layer.

3. The packaging material according to claim 1 or 2, wherein the coating layer, including the outermost coating layer, is a single layer.

4. The packaging material according to claim 1 or 2, wherein the outermost coating layer contains 90% by mass or more of an ionomer resin of an ethylene unsaturated carboxylic acid copolymer with respect to the dry solid content.

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