Packaging material and method for manufacturing the same

Abstract

To provide a packing material with excellent adhesion, printing density, heat sealability, water vapor barrier property, water frictionality, and heat resistance.SOLUTION: A packing material having a heat seal layer, a base material, a printing layer, and a surface protective layer in this order, where the heat seal layer contains polyethylene resin and the surface protective layer contains styrene-acrylic copolymer resin (A). The 60 degree gloss value of the surface protective layer, as measured by the method described in JIS Z8741:1997, is 20 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to packaging materials and methods for producing the same. [Background technology]

[0002] In recent years, it has become common for product packaging and other wrapping materials to be printed for decoration and surface protection. Furthermore, the design, aesthetic appeal, and sense of luxury of printed materials, depending on their quality, can stimulate consumer purchasing intent and thus have significant industrial value.

[0003] Generally, plastic films are primarily used in packaging, and laminated packaging materials have been particularly common. For example, Patent Document 1 describes an invention of a laminated packaging material consisting of a base material, a printed layer, an adhesive layer, and a sealant layer, in which biomass resin is used in the printed layer and the adhesive layer. However, laminated packaging materials inherently use a large amount of plastic film made from petroleum-derived materials. Therefore, there is a demand for paper-based packaging materials that are environmentally friendly, carbon neutral, and can further reduce the amount of plastic used, and technological development is underway to address this.

[0004] For example, as an example of using a paper substrate as part of the packaging material, Patent Document 2 describes an invention relating to a paper laminate having, in sequence, a resin layer, a printed layer, a paper substrate layer, a metal vapor-deposited film layer, a gas barrier coating layer, and a heat-sealable resin layer. However, the resin layer is formed of low-density polyethylene or the like with a low glass transition temperature in order to provide heat sealability, and the toughness of the coating film is insufficient, resulting in problems with the water resistance, friction resistance, and heat resistance of the packaging material.

[0005] For example, Patent Document 3 describes an invention relating to a packaging material having a surface protection layer, a printing layer, a paper substrate layer, and a resin layer in sequence, wherein the surface protection layer contains nitrocellulose. However, since the above surface protection layer is formed solely from nitrocellulose, it lacks water resistance and toughness, resulting in problems with the water abrasion resistance and heat resistance of the packaging material.

[0006] Therefore, there is a demand for packaging materials that do not use a large amount of plastic, such as laminated packaging materials. For example, there is a demand for packaging materials using paper as a base material, but no packaging material has yet been found that satisfies the requirements for excellent water resistance, abrasion resistance, and heat resistance. Thus, in order to make paper-based packaging materials practical, in addition to solving the above problems, it is necessary to improve the adhesion, print density, heat sealability, and water vapor barrier properties required of the packaging material. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2018-051796 [Patent Document 2] Japanese Patent Publication No. 2006-256198 [Patent Document 3] Japanese Patent Publication No. 2020-55171 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The present invention aims to provide a packaging material with excellent adhesion, print density, heat sealability, water vapor barrier properties, water abrasion resistance, and heat resistance. [Means for solving the problem]

[0009] As a result of diligent research into the aforementioned problems, the inventors have found that the above problems can be solved by using the packaging material described below, and have thus come to the present invention.

[0010] In other words, the present invention is a packaging material having a heat-seal layer, a paper substrate, a printing layer, and a surface protection layer in this order, The heat seal layer contains polyethylene resin, The present invention relates to a packaging material in which the surface protective layer contains a styrene-acrylic copolymer resin (A).

[0011] The present invention also relates to the above packaging material, wherein the 60-degree gloss value of the surface protective layer measured by the method described in JIS Z8741:1997 is 20 or less.

[0012] The present invention also relates to the above packaging material, further comprising a barrier layer.

[0013] The present invention also relates to the above packaging material, wherein the printing layer contains at least one selected from the group consisting of a styrene-acrylic copolymer resin (B), a styrene-maleic acid copolymer resin, and an acrylic resin.

[0014] The present invention also relates to a packaging bag formed from the above packaging material.

[0015] The present invention also relates to a method for manufacturing a packaging material having a heat-sealing layer, a paper substrate, a printing layer, and a surface protective layer in this order, a step of forming a printing layer by flexographic printing printing ink on one side of the paper substrate, a step of forming a surface protective layer by flexographic printing an overcoat agent containing a styrene-acrylic copolymer resin on the printing layer, and a step of forming a heat-sealing layer by coating the other side of the paper substrate with molten polyethylene resin, the method for manufacturing a packaging material.

Advantages of the Invention

[0016] According to the present invention, it has become possible to provide a packaging material excellent in adhesion, printing density, heat-sealing property, water vapor barrier property, water friction resistance, and heat resistance. [[ID=3l]]

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example of an embodiment of the present invention, and the present invention is not limited to these contents unless it exceeds the gist thereof.

[0018] In the following explanation, "parts" refers to "parts by mass" unless otherwise specified, and "%" refers to "percent mass." Also, packaging material may sometimes be abbreviated as "laminated body," which is synonymous. In the following description of the present invention, "printing ink" refers to an ink containing pigments and other colorants for forming a printed layer, and "overcoat agent" refers to a coating agent that does not contain pigments and other colorants for forming a surface protective layer. However, this does not mean that small amounts of colorants that may have been unintentionally mixed in are excluded.

[0019] [Packaging material] The present invention relates to a packaging material having a heat-seal layer, a paper substrate, a printing layer, and a surface protection layer in this order, The present invention relates to a packaging material in which the heat-seal layer contains polyethylene resin and the surface protective layer contains styrene-acrylic copolymer resin (A). This configuration improves heat sealability and water abrasion resistance, and the inclusion of styrene-acrylic copolymer resin (A) in the surface protective layer improves heat resistance. The packaging material may further include a barrier layer on the paper substrate layer, and may also include an adhesive resin layer for bonding the barrier layer and the paper substrate layer.

[0020] The following are suitable examples of the laminated structure of the above-mentioned packaging material. In the following examples, " / " represents the boundary between each layer. Heat seal layer / Paper substrate layer / Printing layer / Surface protection layer Heat seal layer / Barrier layer / Paper substrate layer / Printing layer / Surface protection layer Heat seal layer / Paper substrate layer / Barrier layer / Printing layer / Surface protection layer Heat seal layer / Paper substrate layer / Printing layer / Barrier layer / Surface protection layer

[0021] [Surface protection layer] The surface protective layer contains a styrene-acrylic copolymer resin (A). In the surface protective layer, the content of styrene-acrylic copolymer resin (A) is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more, based on the total mass of the surface protective layer. When the content of styrene-acrylic copolymer resin (A) is within the above range, the toughness of the surface protective layer is increased, and the heat resistance of the packaging material is improved. Furthermore, the film thickness of the surface protective layer is preferably 0.3 to 10 μm, more preferably 1 to 7 μm, and even more preferably 3 to 5 μm.

[0022] The gloss value of the surface protective layer is preferably 20 or less, more preferably 10 or less, and even more preferably 5 or less. The above gloss value is the 60-degree gloss value (Gs(60)) measured in accordance with JIS Z 8741:1997. Note that the gloss value mentioned above does not refer to the glossiness (mirror-like reflection) of the metal layer such as the aluminum vapor-deposited layer on the inside of the packaging material, but rather to the gloss value of the outermost surface protective layer. By including a styrene-acrylic copolymer resin (A) in the surface protective layer, it becomes easier to achieve the gloss value of the surface protective layer within the above range.

[0023] <Styrene-acrylic resin (A) contained in the surface protective layer> The styrene-acrylic copolymer resin (A) is preferably an aqueous resin, and this aqueous resin may be a water-soluble resin or an aqueous emulsion resin, but it is preferably an aqueous emulsion resin.

[0024] The styrene-acrylic copolymer resin (A) preferably has acidic groups, and in that case, the acid value is preferably 20 to 200 mg KOH / g, more preferably 30 to 150 mg KOH / g, and even more preferably 80 to 120 mg KOH / g. When the styrene-acrylic copolymer resin (A) has acidic groups and its acid value is within the above range, both water resistance and adhesion can be achieved, resulting in good water abrasion resistance of the packaging material and good adhesion between the printed layer and the surface protective layer.

[0025] The weight-average molecular weight of the styrene-acrylic copolymer resin (A) is preferably 2,000 to 600,000, more preferably 50,000 to 600,000, and particularly preferably 70,000 to 600,000.

[0026] The glass transition temperature of the styrene-acrylic copolymer resin (A) is preferably -20 to 80°C, more preferably -10 to 60°C, and even more preferably 0 to 40°C.

[0027] When the weight-average molecular weight and glass transition temperature of the styrene-acrylic copolymer resin (A) are within the above range, it becomes possible to achieve both toughness and flexibility in the printed layer, resulting in good heat resistance and adhesion between the printed layer and the surface protective layer.

[0028] The above acid value represents the number of milligrams of potassium hydroxide required to neutralize the acidic groups contained in 1 gram of resin solids, and is measured in accordance with JIS K0070.

[0029] The weight-average molecular weight (Mw) can be measured, for example, by GPC (gel permeation chromatography), and can be determined as a converted molecular weight using polyethylene glycol as a standard substance. Suitable measuring instruments include the GPC apparatus Shodex GPC-401 manufactured by Showa Denko, and suitable columns include the Shodex OHpak LB-805 manufactured by Showa Denko. Suitable detectors include RI (differential refractometer), and the measurement temperature is preferably 20-50°C for the column. Suitable eluents include 0.1 N aqueous NaNO3 solutions, and the flow rate is generally 0.2-5.0 mL / min.

[0030] The above glass transition temperature can be measured, for example, using a differential scanning calorimeter (DSC measuring device, Shimadzu Corporation "DSC-60A"), and the temperature at the inflection point in the baseline shift can be used as the glass transition temperature. The measurement is preferably performed under a nitrogen atmosphere, with a measurement temperature range of -100 to 200°C and a heating rate of 1 to 5°C / min.

[0031] <Other resins included in the surface protective layer> The surface protective layer may further contain other resins. Examples of other resins include urethane resins, polylactic acid resins, polyamide resins, vinyl chloride-acrylic copolymer resins, castor oil resins, rosin resins, vinyl acetate resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, acrylic resins, urethane-acrylic resins, styrene-allyl alcohol copolymer resins, styrene-maleic acid copolymer resins, rosin-modified maleic acid resins, dammar resins, and modified resins thereof. These resins can be used individually or in mixtures of two or more.

[0032] The styrene-acrylic copolymer resin (A) included in the surface protective layer may be a commercially available product; for example, BASF's Joncryl 74J, Joncryl 537E, etc., can be used.

[0033] <Additives contained in the surface protective layer> The surface protective layer of the present invention may contain various additives as needed. For example, dispersants, waxes, extender pigments, leveling agents, defoaming agents, film-forming aids, water repellents, and release agents (silicone). Specifically, various additives can be added, such as a dispersion of wax resin fine particles including polyethylene wax to improve abrasion resistance, extender pigments such as silica, barium sulfate, resin beads, calcium carbonate, and talc to improve drying properties and film opacity, inorganic fine particles and adhesive resins (acrylic resin, vinyl acetate resin) to provide anti-slip properties, leveling agents to improve leveling properties, defoaming agents to provide anti-foaming properties, basic compounds such as sodium hydroxide and potassium hydroxide to provide resolubility, and film-forming aids.

[0034] <Overcoat agent> The surface protective layer is preferably formed by an overcoat agent. The overcoat agent is preferably an aqueous overcoat agent. The overcoat agent preferably contains a styrene-acrylic copolymer resin (A) and an aqueous medium, and may further contain resins other than the styrene-acrylic copolymer resin (A) and additives.

[0035] The solid content of the styrene-acrylic copolymer resin (A) in the overcoat agent is preferably 25 to 100% by mass, more preferably 25 to 75% by mass, and particularly preferably 25 to 45% by mass, based on the total mass of the overcoat agent.

[0036] (aqueous medium) The overcoat agent preferably contains an aqueous medium. The main component of the aqueous medium is water. While water is preferred, water-soluble organic solvents can also be used in addition to water. Specifically, depending on the printing conditions (speed, plate depth, design, drying temperature), alcohol-based organic solvents, glycol-based organic solvents, etc., can be included. The content of the aqueous medium is preferably 30% by mass or less of the total amount of the overcoat agent. In this invention, "water as the main component" means that water is the most abundant component in an aqueous medium. Furthermore, a water-soluble organic solvent refers to a solvent that is liquid at 25°C and has a solubility of 1% by mass or more in water at 25°C.

[0037] Examples of the above-mentioned alcohol-based organic solvents include methanol, ethanol, propanol, isopropanol, isobutanol, n-butanol, tertiary-butanol, hexanol, octanol, and decanol.

[0038] Examples of the glycol-based organic solvents mentioned above include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monooctyl ether, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, propylene glycol, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol, dipropyl glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, and dibutyl glycol. These can be used individually, or two or more can be used in combination.

[0039] <Method for manufacturing overcoat agent> The overcoat agent can be obtained by charging a resin solution (in which the resin is dissolved or dispersed in an organic solvent) and a solvent into a stirrer equipped with stirring blades, rotors, etc., and then mixing and stirring them. There are no particular restrictions on the stirring speed, and it can be done at 50 to 2000 rpm. Further solvents may be added as needed to improve the handling and application properties of the overcoat agent. The viscosity of the overcoat agent is preferably 50 to 300 mPa·s from the viewpoint of printability and other factors.

[0040] <Formation of surface protective layer> A surface protective layer can be formed, for example, by printing on the printed layer of a laminate, which has a printed layer on a substrate, using an overcoat agent, and then removing volatile components. A flexographic printing method is one example of a printing method, where, for instance, the overcoat agent is diluted with a diluent solvent to a viscosity and concentration suitable for flexographic printing, supplied to each printing unit either alone or in a mixture, and applied. The surface protective layer can then be obtained by fixing the film through drying in an oven or the like.

[0041] [Print layer] The printed layer is located on the paper substrate side opposite to the side with the heat-seal layer. The printed layer preferably contains an aqueous resin and a colorant.

[0042] The thickness of the printed layer is preferably 0.1 to 10 μm, more preferably 0.3 to 6 μm, and particularly preferably 0.5 to 3 μm. In this invention, not only a single printed layer but also a layer in which multiple printed layers are superimposed can be used as the printed layer, and printed layers with different hues can be arbitrarily combined.

[0043] <Water-based resin contained in the printed layer> The printed layer preferably contains an aqueous resin. Aqueous resins refer to resins that are soluble or dispersible in water, and include water-soluble resins and aqueous emulsion resins. Here, aqueous emulsion resins refer to resins that are insoluble or sparingly soluble in water, but are dispersed and stabilized in water using surfactants or the like.

[0044] The aqueous resin content is preferably 10 to 70% by mass, and more preferably 30 to 50% by mass, of the total mass of the printed layer.

[0045] Examples of water-based resins include acrylic resins, styrene-acrylic copolymer resins (B), styrene-maleic acid copolymer resins, acrylic resins, urethane resins, polylactic acid resins, polyamide resins, vinyl chloride-acrylic copolymer resins, castor oil resins, rosin resins, vinyl acetate resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, styrene-allyl alcohol copolymer resins, rosin-modified maleic acid resins, dammar resins, and modified resins thereof.

[0046] In particular, the aqueous resin preferably contains at least one selected from the group consisting of styrene-acrylic copolymer resin (B), styrene-maleic acid copolymer resin, and acrylic resin, and it is even more preferable that it contains styrene-acrylic copolymer resin (B). This is because it improves the heat resistance and water vapor barrier properties of the packaging material.

[0047] When the aqueous resin includes an aqueous emulsion resin, the average particle size of the aqueous emulsion resin is preferably 10 to 500 nm, and more preferably 30 to 200 nm. The above average particle size is the average particle size in the printing ink when printing ink is used to form the printed layer.

[0048] Furthermore, it is preferable that the aqueous resin contains both the water-soluble resin and the aqueous emulsion. The solid content ratio of the water-soluble resin and the aqueous emulsion resin is preferably 1:99 to 75:25, more preferably 1:99 to 55:45, and particularly preferably 15:85 to 35:65. In the above ratio, a good balance is achieved between the water resistance, toughness, and adhesion of the printed layer, resulting in good water abrasion resistance, heat resistance, and adhesion between the paper substrate and the printed layer in the packaging material.

[0049] Furthermore, the aqueous resin preferably has an acidic group, and it is preferable that the acidic group is neutralized with a basic compound. Examples of acidic groups include hydroxyl groups, aldehyde groups, carbonyl groups, carboxyl groups, etc., with carboxyl groups being preferred. Suitable basic compounds include, for example, amine compounds and alkali metals.

[0050] Examples of the amine compounds mentioned above include ammonia; alkylamines such as diethylamine, triethylamine, and ethylenediamine; and alkanolamines such as monoethanolamine, ethylethanolamine, diethylethanolamine, diethanolamine, and triethanolamine. Examples of the alkali metals mentioned above include sodium hydroxide and potassium hydroxide. These may be used individually or in combination of two or more.

[0051] (Styrene-acrylic copolymer resin (B)) The styrene-acrylic copolymer resin (B) may be a water-soluble styrene-acrylic copolymer resin (b1) used as a water-soluble resin, or a styrene-acrylic copolymer resin emulsion (b2) used as an aqueous emulsion resin.

[0052] (Water-soluble styrene-acrylic copolymer resin (b1)) The water-soluble styrene-acrylic copolymer resin (b1) preferably has acidic groups, and in that case, the acid value is preferably 150 to 350 mg KOH / g, and more preferably 200 to 300 mg KOH / g. When the water-soluble styrene-acrylic copolymer resin (b1) has acidic groups and its acid value is within the above range, both water resistance and adhesion can be achieved, resulting in good water friction resistance and adhesion between the printed layer and the surface protective layer.

[0053] The weight-average molecular weight of the water-soluble styrene-acrylic copolymer resin (b1) is preferably 1500 to 50000, more preferably 1500 to 30000, and particularly preferably 1500 to 8000.

[0054] The glass transition temperature of the water-soluble styrene-acrylic copolymer resin (b1) is preferably 40 to 130°C, and more preferably 60 to 100°C.

[0055] When the weight-average molecular weight and glass transition temperature of the water-soluble styrene-acrylic copolymer resin (b1) are within the above range, it becomes possible to achieve both toughness and flexibility in the printed layer, resulting in good heat resistance and adhesion between the printed layer and the surface protective layer.

[0056] The water-soluble styrene-acrylic copolymer resin (b1) may be a commercially available product; for example, GL-2439 and YL-1098 manufactured by Seikoh PMC can be used.

[0057] (Styrene-acrylic copolymer emulsion (b2)) The styrene-acrylic copolymer resin emulsion (b2) preferably has acidic groups, and in that case, the acid value is preferably 5 to 80 mg KOH / g, and more preferably 20 to 60 mg KOH / g. When the styrene-acrylic copolymer resin emulsion (b2) has acidic groups and its acid value is within the above range, both water resistance and adhesion can be achieved, resulting in good water friction resistance and adhesion between the printed layer and the surface protective layer.

[0058] The weight-average molecular weight of the styrene-acrylic copolymer resin emulsion (b2) is preferably 2,000 to 600,000, and more preferably 10,000 to 600,000.

[0059] The glass transition temperature of the styrene-acrylic copolymer resin emulsion (b2) is preferably -20 to 60°C, and more preferably 0 to 40°C.

[0060] When the weight-average molecular weight and glass transition temperature of the styrene-acrylic copolymer resin emulsion (b2) are within the above range, it becomes possible to achieve both toughness and flexibility in the printed layer, resulting in good heat resistance and adhesion between the printed layer and the surface protective layer.

[0061] The styrene-acrylic copolymer resin emulsion (b2) may be a commercially available product, such as BASF's Joncryl 662, 669, 668, 665, 667, PDX 7198, 633-E, LMV7051, 90, and HPD396.

[0062] (Styrene-maleic acid copolymer resin) Styrene-maleic acid copolymer resins preferably have acid groups, and in that case, the acid value The acid value is preferably 100-180 mgKOH / g, and more preferably 120-160 mgKOH / g. When the styrene-maleic acid copolymer resin has acid groups and its acid value is within the above range, it is possible to achieve both water resistance and adhesion, resulting in good water friction resistance and adhesion between the printed layer and the surface protective layer.

[0063] The weight-average molecular weight of the styrene-maleic acid copolymer resin is preferably 1500 to 50000, and more preferably 4000 to 30000.

[0064] The glass transition temperature of the styrene-maleic acid copolymer resin is preferably 40 to 120°C, and more preferably 60 to 100°C.

[0065] When the weight-average molecular weight and glass transition temperature of the styrene-maleic acid copolymer resin are within the above range, it becomes possible to achieve both toughness and flexibility in the printed layer, resulting in good heat resistance and adhesion between the printed layer and the surface protective layer.

[0066] The styrene-maleic acid copolymer resin may be a commercially available product; for example, M-30 from Seikoh PMC Co., Ltd. or the Alastor series from Arakawa Chemical Co., Ltd. can be used.

[0067] (Acrylic resin) The acrylic resin preferably has acidic groups, and in that case, the acid value is preferably 20 to 100 mg KOH / g, and more preferably 40 to 80 mg KOH / g. When the acrylic resin has acidic groups and its acid value is within the above range, it is possible to achieve both water resistance and adhesion, resulting in good water abrasion resistance and adhesion between the printed layer and the surface protective layer.

[0068] The weight-average molecular weight of the acrylic resin is preferably 1500 to 10000, and more preferably 4000 to 30000.

[0069] The glass transition temperature of the acrylic resin is preferably 10 to 90°C, and more preferably 30 to 70°C.

[0070] When the weight-average molecular weight and glass transition temperature of the acrylic resin are within the above range, it becomes possible to achieve both toughness and flexibility in the printed layer, resulting in good heat resistance and adhesion between the printed layer and the surface protective layer.

[0071] Commercially available acrylic resins may be used; for example, X-310, VS-1057, GL-2439, and TS-1316 from Seikoh PMC can be used.

[0072] <Colorants contained in the printed layer> The printed layer preferably contains a coloring agent. The content of the coloring agent is preferably 1 to 60% by mass, and more preferably 30 to 50% by mass, of the total mass of the printed layer.

[0073] Pigments are preferred as colorants, and either organic or inorganic pigments can be used. For organic pigments, pigments consisting of organic compounds and / or organometallic complexes are preferred. For inorganic pigments, those containing titanium dioxide are preferred.

[0074] Specific examples of organic pigments are shown using their CI numbers from the Colour Index International (CI). Preferably, CI Pigment Red 57:1, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 146, CI Pigment Red 242, CI Pigment Yellow 8 3. CI Pigment Yellow 14, CI Pigment Orange 64, CI Pigment Orange 38, CI Pigment Orange 34, CI Pigment Orange 13, CI Pigment Yellow 180, CI Pigment Yellow 139, CI Pigment Red 185, CI Pigment Red 122, CI Pigment Red 178, CI Pigment Red 149, CI Pigment Red 144, CI Pigment Red 166, CI Pigment Violet 23, CI Pigment Violet 37, CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:6, CI Pigment Green 7, CI Pigment Orange 34, CI Pigment Orange 64, CI Pigment Black 7. These may be used individually or in combination of two or more types.

[0075] (Inorganic pigments) Examples of inorganic pigments include titanium dioxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, aluminum particles, mica, bronze powder, chrome vermilion, lead yellow, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, titanium dioxide, and zinc oxide. Aluminum can be leafing or non-leafing, but the non-leafing type is preferred.

[0076] Titanium dioxide Titanium dioxide can be of any crystalline structure: anatase, rutile, or brookite. Among these, rutile titanium dioxide is preferred due to its good pigment dispersibility. In the industrial production of titanium dioxide, rutile ore or ilmenite ore (FeTiO3) is used as the raw material. There are two main manufacturing methods: the chlorine method and the sulfuric acid method, and either method may be used. Furthermore, to improve printability in flexographic printing, titanium oxide that has been surface-treated is preferable. In particular, titanium oxide that has been surface-treated with at least one metal selected from Si, Al, Zn, Zr, and their oxides is preferable.

[0077] Furthermore, the titanium dioxide preferably has an oil absorption capacity of 14-35 ml / 100g, and more preferably 17-32 ml / 100g, as measured by the method specified in JIS K5101. Also, the titanium dioxide preferably has an average particle size (median particle size) of 0.2-0.3 μm, as measured by a transmission electron microscope. The total titanium dioxide content is preferably 1-60% by mass, and more preferably 10-45% by mass, of 100% by mass of the printing ink. Multiple types of titanium dioxide may be used in combination.

[0078] <Additives contained in the printing layer> The printing layer of the present invention may contain various additives as needed. Examples include dispersants, waxes, extender pigments, leveling agents, defoaming agents, and film-forming aids. Specifically, various additives can be added, such as a dispersion of wax resin fine particles including polyethylene wax to improve abrasion resistance, extender pigments such as calcium carbonate, kaolin, barium sulfate, aluminum hydroxide, clay, and talc to improve drying properties and film opacity, inorganic fine particles and adhesive resins (acrylic resin, vinyl acetate resin) to provide anti-slip properties, leveling agents to improve leveling properties, defoaming agents to provide anti-foaming properties, basic compounds such as sodium hydroxide and potassium hydroxide, and film-forming aids to provide resolubility.

[0079] <Printing Ink> The printed layer is formed by a printing ink containing the above-mentioned colorant and the above-mentioned binder resin. preferable.

[0080] <Method of manufacturing printing ink> Printing inks used to form printed layers can be manufactured, for example, by dispersing pigments in an organic solvent using a disperser with a resin, and then mixing the resulting pigment dispersion with resin, various additives, and organic solvents. Commonly used dispersers such as roller mills, ball mills, pebble mills, attritors, and sand mills can be used. The particle size distribution of the pigment in the pigment dispersion can be adjusted by appropriately adjusting the size of the grinding media in the disperser, the filling rate of the grinding media, the dispersion processing time, the discharge speed of the pigment dispersion, and the viscosity of the pigment dispersion. The viscosity of the printing ink at 25°C is preferably in the range of 50 mPa·s or more from the viewpoint of preventing pigment sedimentation and ensuring adequate dispersion, and 300 mPa·s or less from the viewpoint of workability during ink manufacturing and printing. For example, the method described in Japanese Patent Application Publication No. 2018-158986 can be used as a method for manufacturing printing ink.

[0081] <Formation of the printed layer> The printed layer can be formed, for example, by printing on the paper substrate surface opposite the heat-seal layer using printing ink, and then removing the volatile components. Flexographic printing is preferred as the printing method. For example, the ink is diluted with a diluent solvent to a viscosity and concentration suitable for flexographic printing, supplied to each printing unit either alone or in mixtures, and applied. The printed layer can then be obtained by fixing the film by drying in an oven or the like.

[0082] [Heat seal layer] In this invention, the heat-seal layer is located on the paper substrate side opposite to the side with the printed layer. The heat-seal layer contains polyethylene resin, and as the polyethylene resin, for example, low-density polyethylene resin, linear low-density polyethylene resin, medium-density polyethylene resin, and high-density polyethylene resin can be used. The thickness of the heat-seal layer is preferably 5 to 50 μm. The melting point is preferably 90 to 150°C.

[0083] <Formation of heat seal layer> The heat-seal layer contains polyethylene resin. The heat-seal layer containing polyethylene resin can be formed, for example, by melting polyethylene resin at 300-400°C, extruding the molten polyethylene resin into a film using a slit-shaped device called a T-die, and then laminating and coating the film onto a paper substrate. The heat seal layer may have polyethylene resin as its main component, but may also contain other components. Here, "having polyethylene resin as the main component" means that polyethylene resin has the highest content in the heat seal layer. The heat seal layer preferably contains 80% by mass or more of polyethylene resin, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The thickness of the heat seal layer is preferably 10 to 100 μm, and more preferably 15 to 50 μm.

[0084] [Paper base layer] There are no particular restrictions on the paper substrate layer, and known materials can be used, such as nonwoven fabric, medium-grade paper, fine-grade paper, newsprint, Yupo paper, various coated papers, backing paper, impregnated paper, cardboard, art paper, cast paper, glossy kraft paper, bleached kraft paper, unbleached kraft paper, coated cardboard, ivory paper, card stock, cup base paper, cast paper, light-shielding paper, and paper substrates with surface treatments thereof. Furthermore, a vapor-deposited paper substrate, in which an inorganic compound such as silica, alumina, or aluminum is vapor-deposited onto the paper substrate, can also be used. An anchor layer may be used to uniformly form the vapor-deposited layer on the paper substrate, and the vapor-deposited layer may be further coated with polyvinyl alcohol or the like. In addition, a heat-treated polyethylene or the like may be applied to the vapor-deposited layer. A paper substrate with a sealing resin formed on it may be used. Alternatively, various melamine papers impregnated with melamine resin on the above paper substrate can be used. Among these, single-sided glossy kraft paper, bleached kraft paper, unbleached kraft paper, and uncoated paper without a coating layer such as a vapor-deposited layer are preferred. The paper substrate should be 50 to 150 g / m². 2 Preferably, it is 60-120 g / m² 2 It is even more preferable that the amount be 60-90 g / m².2 It is even more preferable that this be the case.

[0085] [Barrier layer] The packaging material of the present invention preferably has a barrier layer. When the packaging material has a barrier layer, the barrier layer is preferably located between the paper substrate layer and the printing layer, and an inorganic compound layer can be formed on the paper substrate by known methods such as vacuum deposition or sputtering. Alternatively, an aluminum layer can be formed as a barrier layer by laminating aluminum foil on the paper substrate by dry lamination or extrusion lamination.

[0086] The barrier layer preferably contains an inorganic compound, and while not particularly limited, examples of inorganic compounds include aluminum, alumina, and silica. The purity of the inorganic compound is preferably 99% or higher, and more preferably 99.9% or higher.

[0087] <Vacuum deposition method> Vacuum deposition is a method of depositing metals such as aluminum at 1200-1500°C using methods such as high-frequency induction heating, direct current heating, or electron beam heating. -1 ~10 -2 This method involves deposition under conditions of approximately Pa. Before vacuum deposition, the material to be deposited can be treated to improve adhesion, such as by corona discharge treatment on the surface. From the viewpoint of barrier properties, light shielding properties, and cost-effectiveness, the thickness of the metal film formed by vacuum deposition is preferably 10 to 300 nm.

[0088] <Sputtering method> The sputtering method is 10 -1 ~10 -2 This process is carried out by introducing an inert gas such as Ar under conditions of approximately Pa and applying a voltage load. From the viewpoint of barrier properties, light shielding properties, and cost-effectiveness, the thickness of the formed metal film is preferably 10 to 300 nm.

[0089] [Adhesive layer] The packaging material of the present invention may also preferably have an adhesive layer. The adhesive layer can be formed by applying the following adhesives. Suitable adhesives include, but are not limited to, two-component reactive adhesives, acrylic adhesives, anchor coating agents, and molten polyolefin resins. In particular, it is preferable to form the layer by a dry lamination method using a two-component reactive adhesive or by an extrusion lamination method using an anchor coating agent and a molten polyolefin resin.

[0090] <Dry lamination method> The dry lamination method is a method of applying a two-component reactive adhesive consisting of a polyol and a polyisocyanate. The adhesive is diluted to an appropriate viscosity with an organic solvent, applied to the printed surface of the resulting printed material, dried, and then pressed and laminated with a sealant. Examples of such adhesives include TM-250HV / CAT-RT86L-60, TM-550 / CAT-RT37, and TM-314 / CAT-14B, all manufactured by Toyo Morton Co., Ltd.

[0091] <Extrusion lamination method> Extrusion lamination is a method of extruding molten polyolefin resin into a film form through a slit-shaped device called a T-die, and laminating it onto a substrate to bond it to another substrate. For printed materials, an anchor coating agent is often applied to the printed layer before extrusion lamination. Alternatively, the molten polyolefin resin can be extruded onto the printed surface of the printed material, and a sealant can be bonded simultaneously. Imine-based, butadiene-based, and isocyanate-based anchor coating agents can be used. Specifically, Toyo Morton's EL... Examples include -420 (imine-based), EL-452 (butadiene-based), EL-530A / B (isocyanate-based), and EL-540 / CAT-RT32 (isocyanate-based). As meltable polyolefin resins, low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, etc. can be used. Specifically, examples include Novatec LD LC600A (low-density polyethylene) manufactured by Nippon Polyethylene Co., Ltd.

[0092] <Method for manufacturing packaging material> The present invention relates to a method for manufacturing a packaging material having a heat-sealing layer, a paper base material, a printing layer, and a surface protection layer in this order, comprising the steps of: forming a printing layer by flexographically printing printing ink on one side of the paper base material; forming a surface protection layer by flexographically printing an overcoat agent containing a styrene-acrylic copolymer resin on the printing layer; and forming a heat-sealing layer by coating the other side of the paper base material with molten polyethylene resin. By using the flexographic printing method, the printing ink and the overcoat agent can be printed at high speed, resulting in high productivity. The above steps can be carried out in any order, but it is preferable to form the printing layer, the surface protection layer, and the heat-sealing layer in this order.

[0093] As a method for manufacturing a packaging material, the structure of a heat-sealing layer / barrier layer / adhesive resin layer / paper base material layer / printing layer / surface protection layer will be described as an example. Note that the structure of the packaging material in the present invention is not limited to the above.

[0094] First, a dry laminating adhesive TM-250HV / CAT-RT86L-60 is applied onto a paper base material (unbleached kraft paper: kraft paper made from unbleached kraft pulp (manufactured by Nippon Paper Industries Co., Ltd., Ryoshin Kraft K, basis weight 70 g / m 2 ) at an application amount of 4 g / m 2 , and an aluminum foil is bonded thereto to form a barrier layer. A heat-sealing layer is formed by laminating molten polyethylene resin on the barrier layer. Thereafter, a printing layer is formed by flexographically printing printing ink on the side of the paper base material that does not have the barrier layer, and a surface protection layer is formed by flexographically printing an overcoat agent, thereby manufacturing a packaging material having the structure of a heat-sealing layer / barrier layer / adhesive resin layer / paper base material layer / printing layer / surface protection layer.

[0095] [Packaging Bag] The packaging material in this invention can be cut to a predetermined size, and the edges can be heat-sealed by joining the heat-seal layers together to form a packaging bag. The heat-sealing temperature is preferably 50 to 250°C, and more preferably 80 to 180°C. The heat-sealing pressure is 1 to 5 kg / cm². 2 The following conditions are acceptable. A single piece of packaging material may be folded and the edges heat-sealed, or two or more pieces of packaging material may be heat-sealed. Alternatively, the packaging bag may be made by heat-sealing all openings after the contents have been packaged. This packaging bag can be widely used as packaging for food, pharmaceuticals, and other products. [Examples]

[0096] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, parts and % refer to parts by mass and mass %, respectively, unless otherwise noted. Also, "NV." refers to the mass % of non-volatile content.

[0097] <Preparation Example 1> (Preparation of urethane resin solution PU1) In a reactor equipped with a reflux condenser, dropping funnel, gas inlet tube, stirrer, and thermometer, 227.0 parts of polyester polyol (a condensate of adipic acid and 3-methyl-1,5-pentanediol), 9.6 parts of PEG (polyethylene glycol with a number average molecular weight of 2000), 30.1 parts of 2,2-dimethylolpropanoic acid (DMPA), and 250 parts of methyl ethyl ketone (MEK) were mixed and stirred while introducing nitrogen gas. 90.6 parts of (IPDI) were added dropwise over 1 hour, and the mixture was reacted at 80°C for 4 hours to form a terminal isocyanate prepolymer, obtaining a terminal isocyanate prepolymer solution. To the obtained terminal isocyanate prepolymer solution, a mixture of 2.7 parts of 2-aminoethylethanolamine (AEA) and 150 parts of isopropanol (IPA) was gradually added at room temperature, and the mixture was reacted at 40°C for 2 hours to obtain a solvent-type polyurethane resin solution. Next, 38.1 parts of 10% aqueous ammonia and 801.4 parts of deionized water were gradually added to the solvent-type polyurethane resin solution to neutralize it and make it water-soluble. Then, 0.5 parts of an antifoaming agent was added, and MEK and IPA were removed by vacuum distillation. After that, water was added to adjust the solid content, and a urethane resin solution PU1 with a solid content of 28% and a weight-average molecular weight of 38,000 was obtained.

[0098] <Manufacturing Example 1> (Manufacturing of Printing Ink K1) A mixture of 31.6 parts water, 18 parts PigmentBlack7, 5 parts urea compound, and 15 parts styrene-acrylic copolymer resin (A) solution SAC1 (acid value: 213 mg KOH / g, weight-average molecular weight: 8000, glass transition temperature: 73°C, solids content: 28%) was kneaded and dispersed in a bead mill. Then, 27 parts styrene-acrylic copolymer resin (A) emulsion SAC2 (hydroxyl value: 36 mg KOH / g, glass transition temperature: 14°C, solids content: 40%) and 3 parts polyethylene wax were added and stirred to obtain printing ink K1.

[0099] <Manufacturing Examples 2-10> (Manufacturing of printing inks K2-10) Printing inks K2 to K10 were obtained using the same method as in Production Example 1, except that the raw materials and mixing ratios listed in Table 1 were used. The properties of the raw materials used are as follows. • Styrene-maleic acid copolymer resin solution SMA1 (X-228L, manufactured by Seikoh PMC, acid value: 140 mg KOH / g, glass transition temperature: 83°C, solids content: 28%) • Acrylic resin AC1 (AW-36H, manufactured by Seikoh PMC, Acid value: 62 mg KOH / g, Glass transition temperature: 53°C, Solids content: 28%)

[0100] <Manufacturing Example 11> (Manufacturing of Overcoat Agent V1) 4.3 parts of water, 27 parts of styrene-acrylic copolymer resin (A) emulsion SAC3 (acid value 100 mg KOH / g, glass transition temperature: 16°C, solids content 40%), and 3 parts of polyethylene wax were added and stirred to obtain overcoat agent V1.

[0101] <Manufacturing Examples 12-14, Comparative Manufacturing Examples 1 and 2> (Manufacturing of Overcoat Agents V2-6) Overcoat agents V2-6 were obtained using the same method as the manufacturing example, except that the raw materials and mixing ratios listed in Table 1 were used. The properties of the raw materials used are as follows. • Styrene-acrylic resin emulsion SAC4 (acid value: 40 mg KOH / g, glass transition temperature: 49°C, solids content: 40%) • Styrene-acrylic resin emulsion SAC5 (glass transition temperature: 22°C, solids content: 40%) • Urethane resin emulsion PU2 (WBR016U, manufactured by Taisei Fine Chemical Co., Ltd., acid value: 7 mg KOH / g, solids content: 40%) • Acrylic resin emulsion AC2 (acid value: 215 mg KOH / g, weight-average molecular weight: 8500, glass transition temperature: 85°C, solids content: 40%)

[0102] [Table 1]

[0103] <Example 1> (Manufacturing of laminate P1) Next, unbleached kraft paper: Kraft paper made using unbleached kraft pulp (manufactured by Nippon Paper Industries, double-sided kraft K, basis weight 70g / m²). 2 ) versus 250 lines / inch anilox roll, Using a small flexographic printing press equipped with a solid plate made of photosensitive resin, printing ink K1 was printed at a printing speed of 50 m / min, and then dried for 10 seconds with a 1200 W dryer to form a printed layer. On the printed layer, an overcoat agent V1 was printed using a small flexographic printing press equipped with a 200 line / inch anilox roll and a solid plate made of photosensitive resin, at a printing speed of 50 m / min, and then dried at 25°C for 12 hours to obtain an intermediate laminate p1 consisting of a paper substrate / printed layer / surface protective layer. In the intermediate laminate p1, aluminum foil was bonded to the opposite side of the printed layer of the substrate by extrusion lamination under the following conditions: adhesive resin: polyethylene (melting point: 120°C), resin temperature: 330°C, coating speed: 80 m / min, coating thickness: 10 μm. Then, polyethylene resin (melting point: 120°C) was coated onto the aluminum foil under the following conditions: resin temperature: 330°C, coating speed: 80 m / min, coating thickness: 20 μm. This resulted in a packaging material P1 consisting of a heat seal layer, a barrier layer, an adhesive resin layer, a paper substrate, a printed layer, and a surface protection layer.

[0104] <Examples 2-17, Comparative Examples 1-5> (Manufacturing of packaging materials P2-17, P'1-5) Except for the changes in composition and structure shown in Tables 2 and 3, packaging materials P2-17 and P'1-5 were prepared using the same procedure as the preparation of the above-mentioned packaging material. The properties of the raw materials used are as follows. • PP1 (Novatec PP, a polypropylene resin manufactured by Mitsubishi Chemical Corporation)

[0105] [Evaluation of packaging materials] The packaging materials P1-17 and P'1-5 obtained in Examples 1-17 and Comparative Examples 1-5 were evaluated as described below. The results are shown in Tables 2 and 3. In all examples and comparative examples except for Comparative Example 3, which lacked a surface protective layer, it was confirmed that the 60-degree gloss value of the surface protective layer, measured by the method described in JIS Z 8741:1997, was 20 or less.

[0106] <Adhesion> The obtained packaging material was then covered with 15mm wide x 200mm cellophane tape, and the condition of the printed layer when the tape was rapidly peeled off was evaluated according to the following criteria. A, B, and C represent a range that is acceptable for practical use. <Evaluation Criteria> A. The printed layer did not peel off at all. B. More than 80% of the printed layer remained. C.50 or higher, with less than 80% of the printed layer remaining. D. Less than 50% of the printed layer remained.

[0107] <Water friction resistance> The obtained packaging material was cut to a size of 25 mm x 150 mm, and its water resistance and frictional fastness were evaluated using a frictional fastness tester manufactured by Tester Industries Co., Ltd., according to the following criteria. A, B, and C represent ranges that are acceptable for practical use. 《Test Conditions》 Load: 200g, Number of passes: 2, Paper used: Kanakin cloth with 5 drops of water added. Evaluation Criteria A. The printed layer is not removed, and the exposed area ratio of the base paper is less than 1%. B. The paper has a small amount of ink adhering to it. The printed layer has been slightly removed, and the exposed area ratio of the base paper is between 1% and 5%. C. The entire surface of the paper is lightly coated with ink. The printed layer is slightly removed, and the exposed area ratio of the base paper is 5% or more but less than 10%. D. The entire surface of the paper is thinly coated with ink. The printed layer is almost completely removed, and the exposed area ratio of the base paper is 10% or more but less than 20%. E. The entire surface of the paper is heavily inked. The printed layer has been removed, and the exposed area ratio of the base paper is 20% or more.

[0108] <Heat resistance evaluation> The obtained packaging material was cut to a size of 25 mm x 150 mm, and a 25 mm x 150 mm glossy aluminum foil (thickness: 15 μm) was placed on top of the surface protective layer. After heat sealing using the following equipment and conditions, the heat resistance was evaluated according to the following criteria based on the state of the printed layer when the aluminum foil was peeled off. Note that A, B, and C are within a range that is acceptable for practical use. Heat sealing conditions Equipment: Thermal gradient heat sealer [manufactured by Toyo Seiki Co., Ltd.; TYPE HG-100] Seal width: 10mm from the bend, Heater temperature: 160℃ Seal pressure: 2 kg / cm² 2 Seal time: 1 sec Evaluation Criteria A. The printed layer is not removed, and the exposed area ratio of the base paper is less than 1%. B. The paper has a small amount of ink adhering to it. The printed layer has been slightly removed, and the exposed area ratio of the base paper is between 1% and 5%. C. The entire surface of the paper is lightly coated with ink. The printed layer is slightly removed, and the exposed area ratio of the base paper is 5% or more but less than 10%. D. The entire surface of the paper is thinly coated with ink. The printed layer is almost completely removed, and the exposed area ratio of the base paper is 10% or more but less than 20%. E. The entire surface of the paper is heavily inked. The printed layer has been removed, and the exposed area ratio of the base paper is 20% or more.

[0109] <Print density> The obtained packaging materials were evaluated for print density using a PANTONE X-Rite eXact spectrophotometer according to the following criteria. A, B, and C represent ranges that are acceptable for practical use. <Evaluation Criteria> Illuminant / Observer Field of View: D50 / 2°, Density Status: ISO Status E White density reference: The L*, a*, and b* values ​​of the printed surface were measured as absolute values. In addition, the L*, a*, and b* values ​​of the reference standard color were measured and set to 31.20, -3.20, and -22.60 respectively, and the color difference ΔE*ab was calculated using the following formula (1). Formula (1) ΔE*ab = [(ΔL*)² + (Δa*)² + (Δb*)²]¹ / ² <Evaluation Criteria> The ΔE*ab measured with the AX-Rite eXact spectrophotometer is less than 0.4. B.ΔE*ab is between 0.4 and 0.8. C.ΔE*ab is between 0.8 and 1.6. D.ΔE*ab is between 1.6 and 3.2. E.ΔE*ab is 3.2 or greater.

[0110] <Heat sealability evaluation> The obtained packaging material was cut to a size of 15 mm x 100 mm, folded so that the heat-sealed layers overlapped, and heat-sealed using the following equipment and conditions. The unsealed ends were then fixed to a small tensile testing machine to evaluate the heat-seal strength. A, B, and C represent ranges that are acceptable for practical use. Heat sealing conditions Equipment: Heat seal tester manufactured by Tester Industries Co., Ltd., seal width: from the bent part 10mm, heater temperature: 160℃, sealing pressure: 2kg / cm² Seal time: 1 sec Heat seal strength measurement conditions Equipment: Intesco small tensile testing machine (model: IM-20), specimen width: 15 mm, peel mode: 90° peel, tensile speed: 300 mm / min Evaluation Criteria A. The heat seal strength is 5.0 N or higher. B. The heat seal strength is 3.5N or more and less than 5.0N. C. The heat seal strength is 1.0 N or more and less than 3.5 N. D. The heat seal strength is less than 1.0 N.

[0111] <Water vapor barrier properties> The obtained packaging materials were subjected to moisture permeability measurements in accordance with JIS Z0208, and their water vapor barrier properties were evaluated based on the following criteria. A, B, and C represent ranges that are acceptable for practical use. Evaluation Criteria Evaluation time: 15 hours Evaluation Criteria A. Moisture permeability of 5g / m 2 • Less than 15 hours B. Moisture permeability of 5g / m 2 ·15h or more, 1000g / m 2 • Less than 15 hours C. Moisture permeability of 1000g / m 2 ·15h or more, 3000g / m 2 • Less than 15 hours D. Moisture permeability of 3000g / m 2 • It is 15 hours or longer.

[0112] [Table 2]

[0113] [Table 3]

[0114] The present invention provides a packaging material with excellent adhesion, print density, heat sealability, water vapor barrier properties, water abrasion resistance, and heat resistance. In particular, Comparative Example 2, which included polypropylene resin in the heat seal layer, did not meet the standard for heat sealability, and Comparative Example 4, which included polyurethane resin in the surface protective layer, and Comparative Example 5, which included acrylic resin, did not meet the standard for heat resistance.

Claims

1. A packaging material having a heat-seal layer, a paper substrate, a printing layer, and a surface protection layer in this order, The paper substrate and the printing layer are in contact, and the printing layer and the surface protective layer are in contact, The heat seal layer contains polyethylene resin, The surface protective layer comprises a styrene-acrylic copolymer resin (A), The printing layer comprises a styrene-acrylic copolymer resin (B) and / or a styrene-maleic acid copolymer resin. The 60-degree gloss value of the surface protective layer, measured by the method described in JIS Z 8741:1997, is 20 or less. packaging material.

2. The packaging material according to claim 1, further comprising a barrier layer located between the heat seal layer and the paper substrate layer.

3. A packaging bag formed from the packaging material described in claim 1.

4. A method for manufacturing a packaging material having a heat-seal layer, a paper substrate, a printing layer, and a surface protection layer in this order, The paper substrate and the printing layer are in contact, and the printing layer and the surface protective layer are in contact, A step of forming the printed layer on one side of the paper substrate by flexographic printing a printing ink containing styrene-acrylic copolymer resin (B) and / or styrene-maleic acid copolymer resin. A step of forming the surface protective layer by flexographic printing an overcoat agent containing a styrene-acrylic copolymer resin onto the printed layer, and The process includes a step of coating the other side of the paper substrate with molten polyethylene resin to form the heat seal layer, A method for manufacturing packaging material, wherein the 60-degree gloss value of the surface protective layer, as measured by the method described in JIS Z 8741:1997, is 20 or less.

5. A method for manufacturing a packaging material comprising a heat seal layer, a barrier layer, a paper substrate, a printing layer, and a surface protection layer in this order, The paper substrate and the printing layer are in contact, and the printing layer and the surface protective layer are in contact, A step of forming the barrier layer on one side of the paper substrate, A step of forming the printed layer on the other side of the paper substrate by flexographic printing a printing ink containing a styrene-acrylic copolymer resin (B) and / or a styrene-maleic acid copolymer resin. A step of forming the surface protective layer by flexographic printing an overcoat agent containing a styrene-acrylic copolymer resin onto the printed layer, and The process includes a step of coating the side of the paper substrate having a barrier layer with molten polyethylene resin to form a heat seal layer, A method for manufacturing packaging material, wherein the 60-degree gloss value of the surface protective layer, as measured by the method described in JIS Z 8741:1997, is 20 or less.

Images