Packaging material and method for manufacturing the same

Abstract

To provide a packing material excellent in bending resistance, wet friction resistance, blocking resistance, and heat sealability.SOLUTION: In a packing material having a heat seal layer, a paper base material, and a first surface protective layer in this order, the first surface protective layer contains an urethane resin (A) and a resin (B), the resin (B) contains a vinyl resin and / or a cellulose-based resin, and the coating amount of the first surface protective layer is in the range of 3 to 20 g / m2. Where, the resin (B) does not contain an urethane resin.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, packaging consists of packaging materials, and these materials are mainly made of plastic film. Because they are transparent, they can be used in a way that allows the contents to be seen, and laminate packaging materials have been used particularly often. For example, Patent Document 1 describes an invention of a laminate 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, laminate packaging materials inherently use a large amount of petroleum-derived plastic film. Therefore, there is a demand for packaging materials that are environmentally friendly, carbon neutral, and can further reduce the amount of plastic used, and technological development is underway to meet this need.

[0004] For example, Patent Document 2 describes an invention relating to a protective sheet having a layer containing urethane resin and vinyl resin on a paper substrate. However, the amount of this layer applied is 2.6 g / m². 2 Therefore, there are issues with its bending resistance and water abrasion resistance. In addition to solving the above issues, it is necessary to improve the blocking resistance and heat sealability required for packaging materials.

[0005] Therefore, no packaging material has yet been found that satisfies the requirements for bending resistance, water and abrasion resistance, blocking resistance, and heat sealability. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Unexamined Patent Publication No. 2018-051796 [Patent Document 2] Japanese Unexamined Patent Publication No. 2021-28168 [Summary of the Invention] [Problem to be Solved by the Invention]

[0007] An object of the present invention is to provide a packaging material that can simultaneously satisfy bending resistance, water friction resistance, blocking resistance, and heat sealability, and a method for producing the same. [Means for Solving the Problem]

[0008] As a result of intensive studies on the above problem, the present inventor has found that the above problem can be solved by using the packaging material described below, and has accomplished the present invention.

[0009] That is, the present invention is a packaging material having a heat seal layer, a paper base material, and a first surface protective layer in this order, wherein the first surface protective layer contains a urethane resin (A) and a resin (B) other than the urethane resin (A), the resin (B) contains a vinyl-based resin and / or a cellulose-based resin, the coating amount of the first surface protective layer is 3 to 20 g / m 2 , which relates to a packaging material.

[0010] The present invention also relates to the above packaging material, wherein the resin (B) other than the urethane resin (A) is a vinyl-based resin, and the vinyl-based resin is at least one selected from the group consisting of vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-acrylic copolymer resins, and polyvinyl acetal resins.

[0011] The present invention also relates to the above packaging material, wherein the elastic modulus of the first surface protective layer at 25°C measured according to JIS K 7244-4 is 1.0×10 8 to 1.5×10 9 Pa, which relates to the above packaging material.

[0012] Furthermore, the present invention relates to the above-mentioned packaging material, wherein the loss coefficient of the first surface protective layer at 25°C, as measured according to JIS K 7244-4, is 0.1 to 0.7.

[0013] Furthermore, the present invention relates to the above-mentioned packaging material, wherein the heat-seal layer comprises at least one selected from the group consisting of polyolefin resin, acrylic resin, and urethane resin (E).

[0014] Furthermore, the present invention relates to the above-mentioned packaging material in which the urethane resin (A) contains structural units derived from polyester.

[0015] Furthermore, the present invention relates to the above-mentioned packaging material, wherein the urethane resin (A) comprises a urethane resin (A1) with a total amine value (mgKOH / g) of 1 or more and less than 10, and a urethane resin (A2) with a total amine value (mgKOH / g) of 10 or more and 20 or less.

[0016] Furthermore, the present invention relates to a packaging material having a second surface protection layer, wherein the layer configuration of the packaging material is in the order of a heat seal layer, a paper substrate, a first surface protection layer, and a second surface protection layer.

[0017] Furthermore, the present invention relates to the above-mentioned packaging material wherein the second surface protective layer contains a cellulose resin.

[0018] Furthermore, the present invention relates to the above-mentioned packaging material wherein the second surface protective layer further comprises a polyamide resin.

[0019] Furthermore, the present invention relates to a method for manufacturing a packaging material having, in sequence, a heat-seal layer, a paper substrate, and a first surface protective layer. A process of forming a heat seal layer on one side of a paper substrate by gravure printing a heat seal agent, A first overcoat agent containing urethane resin (A) and a resin other than urethane resin (B) is gravure printed onto the other side of a paper substrate, with a coating amount of 3 to 20 g / m². 2 The process of forming the first surface protective layer, This relates to a method for manufacturing packaging materials, including the present invention. [Effects of the Invention]

[0020] The present invention makes it possible to provide a packaging material with excellent bending resistance, water abrasion resistance, blocking resistance, and heat sealability. [Modes for carrying out the invention]

[0021] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is merely an example of embodiments of the present invention, and the present invention is not limited to these contents unless it exceeds the gist of the invention.

[0022] In the following explanation, "parts" refers to "parts by mass" unless otherwise specified, and "%" refers to "percentage by mass." Also, packaging materials may sometimes be described as "laminated bodies," but these are synonymous. Furthermore, "printing ink" refers to ink containing pigments and other colorants for forming the printed layer. "First overcoat agent" refers to a coating agent that does not contain pigments and other colorants for forming the first surface protective layer, but does not exclude small amounts of colorants that may have been unintentionally mixed in. "Second overcoat agent" refers to a coating agent that does not contain pigments and other colorants for forming the second surface protective layer, but does not exclude small amounts of colorants that may have been unintentionally mixed in.

[0023] [Packaging material] The packaging material of the present invention is a packaging material having, in sequence, a heat-seal layer, a paper substrate, and a first surface protective layer, The first surface protective layer comprises a urethane resin (A) and a resin other than urethane resin (B) (hereinafter also referred to as resin (B)). The resin (B) includes a vinyl resin and / or a cellulose resin. The coating amount of the first surface protective layer is 3-20 g / m². 2 That is the case.

[0024] [First surface protective layer] Due to the flexibility of the urethane resin (A), the first surface protective layer used in the present application can suppress the occurrence of cracks in the coating film when the packaging material is folded, and is excellent in bending resistance. In addition, due to the toughness of the resin (B), even when the coating film is rubbed in a water-wet state, damage to the coating film can be suppressed, resulting in excellent water friction resistance. In addition, by setting the coating amount within the above range, a uniform coating film free of cracks and the like can be formed on the paper substrate, and the resulting layer is excellent in bending resistance and water friction resistance. The first surface protective layer of the present application contains urethane resin (A) and resin (B), and is located on the opposite side of the paper substrate from the side provided with the heat seal layer. The first surface protective layer can be formed from a first overcoat agent.

[0025] The coating amount of the first surface protective layer is 3 to 20 g / m 2 , more preferably 6 to 17 g / m 2 , and particularly preferably 10 to 14 g / m 2 . When the coating amount falls within the above range, good bending resistance and water friction resistance can be obtained.

[0026] At 25°C, the elastic modulus of the first surface protective layer is 1×10 8 to 1.1×10 9 Pa, more preferably 2×10 8 to 7×10 8 Pa, and still more preferably 2.5×10 8 to 5×10 8 Pa. When the elastic modulus falls within the above range, good water friction resistance can be obtained.

[0027] At 25°C, the loss factor of the first surface protective layer is preferably 0.15 to 0.65, and more preferably 0.35 to 0.55. As shown in the following formula, the loss factor represents the ratio of the viscosity modulus to the elastic modulus. The elastic modulus correlates with the toughness of the coating film, and the viscosity modulus correlates with the stretchability of the coating film. Therefore, when the loss factor falls within the above range, the toughness and stretchability of the coating film are well balanced, resulting in excellent water friction resistance and bending resistance. (Formula 1) Loss factor = (Viscosity modulus) / (Elastic modulus)

[0028] The above elastic modulus and loss coefficient are values ​​measured in accordance with JIS K 7244-4.

[0029] <Urethane resin (A)> The urethane resin (A) preferably comprises urethane resin (A1) with a total amine value (mgKOH / g) of 1 or more and less than 10, and / or urethane resin (A2) with a total amine value (mgKOH / g) of 10 or more and 20 or less. A preferred form is one comprising urethane resin (A1) and urethane resin (A2).

[0030] Measurement of amine value The above amine value represents the equivalent amount of potassium hydroxide (in mg) required to neutralize the amino groups contained in 1 g of resin, which is equivalent to the amount of hydrochloric acid needed to neutralize the amino groups. The method for measuring the amine value is as follows: [Method for measuring amine value] Weigh 5-10 g of the sample accurately (S: mass of solids in the sample (g)). Add 25 mL of toluene and 25 mL of n-butanol to the weighed sample and dissolve thoroughly. Add 30 mL of methanol and perform potentiometric titration with 0.1 mol / L hydrochloric acid aqueous solution (titer: f). The amine value can be determined using the titration volume (A mL) and the following formula.

[0031] (Formula 2) Amine value = (A × f × 0.1 × 56.108) / S [mgKOH / g]

[0032] 《Urethane resin (A1) with a total amine value (mgKOH / g) of 1 or more and less than 10》 The urethane resin (A1) contains at least one selected from the group consisting of primary amines, secondary amines, and tertiary amines. The total amine value refers to the sum of the amine values ​​of the primary amines, secondary amines, and tertiary amines in the system. The total amine value (mgKOH / g) of the urethane resin (A1) is preferably 1 or more and less than 10, more preferably 5 to 9.5 mgKOH / g, and even more preferably 7 to 9 mgKOH / g. When the value is within the above range, the flexibility of the coating film can be maintained even when a curing agent is added, thus improving bending resistance.

[0033] The total amine value of the primary and secondary amines in the urethane resin (A1) is preferably 0.5 to 7, more preferably 1 to 5, and even more preferably 1.5 to 3. When the amine value is within this range, the flexibility of the coating film can be maintained even when a curing agent is added, thus improving its bending resistance.

[0034] The total amine value of the primary and secondary amines in urethane resin (A1) was calculated using the following formula. Here, the total amine value can be obtained from formula 2.

[0035] (Formula 3)

[0036] TIFF0007920816000001.tif17161

[0037] p i : Weight (g) of the i-th polyamine contained in 1g of the finished resin solution f A3,i : Number of tertiary amino groups contained in the i-th amine m i : Molecular weight of the i-th amine W: Non-volatile content of the finished resin solution

[0038] The urethane resin (A1) can be any known urethane resin, such as polyester-based urethane resin, polyether-based urethane resin, polycarbonate-based urethane resin, or polyolefin-based urethane resin, but polyester-based urethane resin is preferred.

[0039] The hydroxyl value of the urethane resin (A1) is preferably 0.1 to 10 mg KOH / g, more preferably 0.3 to 5 mg KOH / g, and even more preferably 0.5 to 1 mg KOH / g. When it is within the above range, the water friction resistance is good.

[0040] The acid value of the urethane resin (A1) is preferably 5 mg KOH / g or less, and more preferably 3 mg KOH / g or less. The acid value is given by acidic groups such as carboxyl groups, but minimizing the acid value ensures good adhesion to the substrate.

[0041] The glass transition temperature of the urethane resin (A1) is preferably -20 to 60°C, more preferably -10 to 40°C, and even more preferably -10 to 20°C. When the temperature is within the above range, the toughness of the coating film is improved, and the water resistance and abrasion resistance are improved.

[0042] The weight-average molecular weight of the urethane resin (A1) is preferably 10,000 to 100,000, more preferably 15,000 to 85,000, and even more preferably 25,000 to 70,000. When the molecular weight is within the above range, the toughness of the coating film is improved, and the water-resistant abrasion properties are also improved.

[0043] The molecular weight distribution (Mw / Mn) of the urethane resin (A1) is preferably 2.0 to 8.0, more preferably 2.5 to 7.0, and even more preferably 3.0 to 6.0.

[0044] Measurement of hydroxyl value In this application, the hydroxyl value is calculated by acetylating the hydroxyl groups in the resin with an excess acetylating reagent, back-titrating the remaining acid with an alkali, and then converting the amount of hydroxyl groups per gram of resin to the number of milligrams of potassium hydroxide, in accordance with JIS K 0070.

[0045] 《Measurement of Acid Value》 In this application, the acid value is the number of milligrams of potassium hydroxide required to neutralize the acidic groups contained in 1 g of resin solids, and is measured in accordance with JIS K 0070.

[0046] Measurement of glass transition temperature In this application, the glass transition temperature was measured by simultaneous thermogravimetric and differential thermal analysis (TG-DTA) using a Shimadzu DTG-60A. Specifically, under conditions of a nitrogen atmosphere, a measurement temperature range of -100 to 200°C, and a heating rate of 1°C / min, the temperature at the inflection point in the baseline shift was defined as the glass transition temperature.

[0047] Measurement of weight-average molecular weight The weight-average molecular weight (weight-average molecular weight), number-average molecular weight (Mn), and molecular weight distribution (weight-average molecular weight / Mn) were measured by GPC (gel permeation chromatography) and determined as converted molecular weights using polystyrene as a standard substance. GPC device: Showa Denko Shodex GPC-104 Columns: The following columns were used, connected in series. Two Shodex LF-404 tubes manufactured by Showa Denko. Showa Denko Shodex LF-G Detector: RI (Differential Refractometer) Measurement conditions: Column temperature 40°C Eluent: Tetrahydrofuran Flow rate: 0.5mL / min

[0048] (Polyester-based urethane resin) Polyester-based urethane resin refers to a urethane resin having constituent units derived from polyester. Preferably, it has a form containing urea bonds. For example, if the following polyester polyol is used as a raw material, the urethane resin will have constituent units derived from polyester. It is preferable that the total mass of the polyester-based urethane resin contains 40% by mass or more of polyester-derived structural units, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 65% ​​by mass or more. Polyester-based urethane resins are not limited to the following, but examples include polyester-based urethane resins obtained by reacting a urethane prepolymer, which is obtained by reacting a polyisocyanate with a polyol containing a polyester polyol, with a polyamine (chain extender) and, if necessary, a reaction inhibitor. In order to obtain a urethane resin having constituent units derived from polyester, for example, the polyol in the above-mentioned method for synthesizing the urethane resin is not particularly limited.

[0049] (Polyester polyol) The number-average molecular weight of the polyester polyol described above is preferably 500 to 10,000, and more preferably 1,000 to 5,000. Here, the number-average molecular weight is calculated from the hydroxyl value, which is the amount of hydroxyl groups per gram of resin calculated by esterifying or acetylating the hydroxyl groups in the resin and back-titrating the remaining acid with an alkali, and then converting this amount to the number of milligrams of potassium hydroxide. This value was measured according to JIS K 0070. When the number-average molecular weight of the polyester polyol is 10,000 or less, it exhibits excellent blocking resistance. Furthermore, when the number-average molecular weight of the polyester polyol is 500 or more, the flexibility of the coating film is improved, and its bending resistance is good.

[0050] The polyester polyol is preferably a polyester diol, and more preferably a polyester diol that is a condensate of a diol and a dicarboxylic acid (also called a dibasic acid). The polyester polyol can be used alone or in a mixture of two or more types.

[0051] Examples of raw materials for the above polyester polyols include alkanediols, 1-monoglycerides, 2-monoglycerides, 1-monoglycerin ethers, 2-monoglycerin ethers, dimer diols, hydrogenated dimer diols, etc., and as 1,2-alkanediols, Suitable examples include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3,5-trimethylpentanediol, 2,4-diethyl-1,5-pentanediol, and 1,12-octadecanediol.

[0052] The above-mentioned diols can be classified into linear diols and branched diols. Linear diols impart crystallinity, while branched diols impart flexibility, and the balance between these two improves the heat resistance of the polyurethane resin used as a binder. It is also believed that the inclusion of branched diol structures and / or linear diol structures in the polyurethane resin is beneficial for the efficiency of packaging material recycling. As will be described later, it is more preferable for the polyurethane resin to include both branched and linear diol structures.

[0053] The linear diol mentioned above is preferably an alkylene glycol, and examples include ethylene glycol, polyethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, and 1,4-butynediol. Among these, linear diols having 8 or fewer carbon atoms, preferably 6 or fewer carbon atoms, are preferred, with ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, and the like being preferred. Furthermore, from the viewpoint of physical properties, 1,3-propanediol is particularly preferred.

[0054] Examples of the above-mentioned branched diols include 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,2-propylene glycol, 2,4-diethyl-1,5-pentanediol, 1,3-butanediol, and dipropylene glycol, with at least one branched diol selected from neopentyl glycol and 1,2-propylene glycol being particularly preferred.

[0055] When a polyester polyol contains branched diols and linear diols, from the viewpoint of lamination strength, the mass ratio of branched diols to linear diols (branched diol:linear diol) in the total diols of the polyester polyol is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0056] Furthermore, branched diol units and linear diol units may each be present in a single polyester polyol, or a mixture of polyester polyols containing only branched diol units and polyester polyols containing only linear diol units may be used as raw materials to produce a biomass urethane resin. Approximately the same effect can be obtained.

[0057] Suitable examples of the above-mentioned dicarboxylic acids include adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, glutaric acid, 1,4-cyclohexyldicarboxylic acid, dimer acid, and hydrogenated dimer acid, with adipic acid, succinic acid, and sebacic acid being particularly preferred. Furthermore, polyols having three or more hydroxyl groups and polycarboxylic acids having three or more carboxyl groups can also be used in combination as raw materials for polyester polyols.

[0058] Among these, a preferred example of a polyester polyol is one that contains both branched and linear diols, along with dicarboxylic acids such as adipic acid, succinic acid, and sebacic acid. This results in better laminate strength in the packaging material.

[0059] (Polyisocyanate) Diisocyanates are preferred as polyisocyanates in polyester-based urethane resins, and various known aromatic, aliphatic, or alicyclic diisocyanates can be used. For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzylu isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropyl diisocyanate, methylene diisocyanate, 2,2,4-tri Representative examples include methylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanate-methyl)cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanates obtained by converting the carboxyl groups of dimer acids to isocyanate groups. These can be used individually or in combination of two or more. Among these, isophorone diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and hexamethylene diisocyanate are preferred, and hexamethylene diisocyanate is preferred from the viewpoint of improving bending resistance and water friction resistance.

[0060] (Hexamethylene diisocyanate) Hexamethylene diisocyanate is preferably in the form of a dimer or trimer. Trimers exist in the form of biuret, isocyanurate, and adduct chemical structures. From the viewpoint of improving bending resistance and water friction resistance, the isocyanurate trimer and dimer are preferred, and the isocyanurate trimer is more preferred.

[0061] (Polyamines) The polyamines of this application include primary amines, secondary amines, and tertiary amines. Examples of primary and secondary amines include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 2-hydroxyethylpropyldiamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, di-2-hydroxypyropyrethylenediamine, diethylenetriamine, triethylenetetramine, N-(2-hydroxyethyl)ethylenediamine, N-(2-hydroxyethyl)propylenediamine, N-(2-hydroxypyropyrethylenediamine, iminobispropylamine:(IBPA, 3,3'-diaminodipropylamine), N-(3-aminopropyl)butane-1,4-diamine:(spermidine), 6,6-iminodihexylamine, 3,7-diazanonane-1,9-diamine, and N,N'-bis(3-aminopropyl)ethylenediamine. Examples of tertiary amines include 3-dimethylamino-1-propylamine and N,N-bis-(3-dimethylamino-1-propyl)amine. Preferably, the polyamines are isophoronediamine, 2-hydroxyethylethylenediamine, hexamethylenediamine, and iminobispropylamine. These polyamines can be used individually or in combination of two or more.

[0062] 《Urethane resin (A2) with a total amine value (mgKOH / g) of 10 to 20》 Urethane resin (A2) differs from urethane resin (A1) in its preferred amine value and weight-average molecular weight, but for other aspects, the description above for (urethane resin A1) can be applied.

[0063] The total amine value of the urethane resin (A2) is preferably 10 to 20, more preferably 10.5 to 16 mg KOH / g, and even more preferably 11 to 13 mg KOH / g. When the value is within the above range, the cohesive force of the coating film when the curing agent is added is improved, resulting in improved bending resistance and water friction resistance.

[0064] The total amine value of the primary and secondary amines in the urethane resin (A2) is preferably 3 to 13 mg KHO / g, more preferably 5 to 11 mg KOH / g, and even more preferably 7 to 9 mg KOH / g. When the value is within the above range, the cohesive force of the coating film when the curing agent is added is improved, resulting in improved bending resistance and water friction resistance.

[0065] The weight-average molecular weight of the urethane resin (A2) is preferably 10,000 to 100,000, more preferably 15,000 to 60,000, and even more preferably 20,000 to 40,000. When the molecular weight is within the above range, the cohesive strength of the coating film is improved, resulting in improved bending resistance and water friction resistance.

[0066] The mass ratio of urethane resin (A1) to urethane resin (A2) is preferably 25:75 to 85:15, more preferably 35:65 to 75:25, and even more preferably 45:55 to 65:35. When the ratio is within the above range, good bending resistance and water abrasion resistance are obtained.

[0067] <Resins other than urethane resin (A) (B)> Resin (B) includes vinyl resins and / or cellulosic resins. A preferred form of resin (B) is a vinyl resin.

[0068] Resin (B) may further include polyamide resins, rosin-based resins, acrylic resins, styrene resins, dammar resins, styrene-maleic acid copolymer resins, polyester resins, alkyd resins, terpene resins, phenol-modified terpene resins, ketone resins, cycloplastic rubbers, butyral, polyacetal resins, and modified resins thereof, and these resins may be used individually or in combination of two or more.

[0069] Vinyl resin Vinyl resins include structures formed by polymerizing monomers containing a vinyl group. Examples of vinyl resins include vinyl chloride resin, vinyl acetate resin, vinyl chloride copolymer resin, and polyvinyl acetal resin, with vinyl chloride copolymer resin and polyvinyl acetal resin being preferred. Examples of vinyl chloride copolymer resins include vinyl chloride-vinyl acetate copolymer resin and vinyl chloride-acrylic copolymer resin. More preferably, the vinyl resin is vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, or polyvinyl acetal resin, and even more preferably vinyl chloride-acrylic copolymer resin.

[0070] (Vinyl chloride-acrylic copolymer resin) Vinyl chloride-acrylic copolymer resin mainly consists of a copolymer of vinyl chloride and acrylic monomer, and the acrylic monomer is a monomer having an acrylic group or a methacrylic group, and preferably contains an acrylic monomer having a hydroxyl group. (Hereinafter, "acrylic" may be referred to as "(meth)acrylic.") The vinyl chloride-acrylic copolymer resin may be produced by block copolymerization or random copolymerization of vinyl chloride and acrylic monomer, or by graft copolymerization in which acrylic monomer is grafted onto the side chains of polyvinyl chloride.

[0071] The vinyl chloride-acrylic copolymer resin preferably has a weight-average molecular weight of 10,000 to 100,000, and more preferably 30,000 to 70,000. The glass transition temperature is preferably 50 to 90°C, more preferably 55 to 85°C, and even more preferably 65 to 80°C. The hydroxyl acid value is preferably 10 to 120 mgKOH / g, more preferably 20 to 110 mgKOH / g, even more preferably 30 to 100 mgKOH / g, and particularly preferably 40 to 80 mgKOH / g. The vinyl chloride-derived structure in the vinyl chloride-acrylic copolymer resin is preferably 70 to 95% by mass of 100% by mass of the solid content of the vinyl chloride-acrylic copolymer resin.

[0072] Examples of (meth)acrylic monomers having a hydroxyl group include hydroxyalkyl (meth)acrylates, such as hydroxyalkyl (meth)acrylate esters including 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 1,4-cyclohexanedimethanol mono(meth)acrylate; caprolactone-modified (meth)acrylate; and hydroxyethylacrylamide. Among these, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate are preferred. These can be used individually or in combination of two or more.

[0073] The (meth)acrylic monomer may also include alkyl (meth)acrylate esters. The alkyl group in the alkyl (meth)acrylate ester preferably has 1 to 20 carbon atoms. Examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, etc. Furthermore, the alkyl group may have an aromatic ring structure substituted with an aryl group or the like. These can be used individually or in combination of two or more.

[0074] Furthermore, (meth)acrylic monomers may have functional groups other than hydroxyl groups, such as carboxyl groups, amide groups, amino groups, alkylene oxide groups, and the like.

[0075] For the vinyl chloride-acrylic copolymer resin, commercially available products from the Solvine A-type series (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used.

[0076] (Vinyl chloride-vinyl acetate copolymer resin) The vinyl chloride-vinyl acetate copolymer resin is a resin copolymerized with at least vinyl chloride and vinyl acetate, and its weight-average molecular weight is preferably 5,000 to 100,000, more preferably 20,000 to 70,000. The structure derived from vinyl acetate monomer is preferably 1 to 30% by mass, and the structure derived from vinyl chloride monomer is preferably 70 to 95% by mass, in 100% by mass of the solids content of the vinyl chloride-vinyl acetate copolymer resin. Furthermore, to improve solubility in organic solvents, it is even more preferable that the resin contains hydroxyl groups derived from vinyl alcohol through saponification or copolymerization, and the hydroxyl value is preferably 20 to 200 mg KOH / g. The glass transition temperature is preferably 50°C to 90°C.

[0077] For the vinyl chloride-acrylic copolymer resin, commercially available products from the Solvine C-type series (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used.

[0078] (Polyvinyl acetal resin) Polyvinyl acetal resin is obtained by reacting polyvinyl alcohol with butyraldehyde and / or formaldehyde to form an acetal ring, and preferably contains vinyl alcohol units, vinyl acetate units, and acetal ring groups. The polyvinyl acetal resin preferably contains 60 to 90% by mass of acetal rings, 5 to 30% by mass of vinyl alcohol units, and 0.5 to 10% by mass of vinyl acetate units, and more preferably is a polyvinyl butyral resin having a butyral ring as the acetal ring. The weight-average molecular weight of the polyvinyl acetal resin is preferably 10,000 to 100,000, more preferably 10,000 to 80,000. The glass transition temperature of the polyvinyl acetal resin is preferably 50 to 80°C, more preferably 60 to 75°C.

[0079] For the polyvinyl acetal resin, commercially available products such as the S-Rec BL series (manufactured by Sekisui Chemical Co., Ltd.) can be used.

[0080] Cellulose resin Cellulose resins are resins obtained by esterification or nitration of cellulose resins derived from non-edible plants such as wood fibers and cotton. Examples include cellulose acetate resin, cellulose acetate butyrate resin, cellulose acetate resin, cellulose acetate butyrate resin, cellulose acetate propionate resin, and nitrocellulose resin. From the viewpoint of heat resistance and gloss, nitrocellulose resin is preferred. These may be used individually or in combination of two or more types.

[0081] It is preferable that the viscosity of the cellulose resin, as measured in accordance with JIS K 6703-1995, satisfies at least one of the following conditions (1) to (3). The viscosity is the time it takes for a steel ball to fall through the isopropanol solution of the cellulose resin (steel ball fall time (seconds)). (1) The viscosity at a solution concentration of 12.2% by mass is 1.5 to 16 seconds. (2) The viscosity at a solution concentration of 20% by mass is 3 to 40 seconds. (3) The viscosity at a solution concentration of 25% by mass is 0.1 to 22 seconds. In particular, the viscosity of the cellulose resin is preferably such that it satisfies the above condition (3). In the above condition (3), the viscosity at a solution concentration of 25% by mass is preferably 0.3 to 15 seconds, and more preferably 0.5 to 9 seconds. When the viscosity is within the above range, the heat resistance and blocking resistance of the first surface protective layer are good.

[0082] The weight-average molecular weight (Mw) of the cellulose resin is preferably 2,000 to 200,000, more preferably 8,000 to 100,000, and even more preferably 10,000 to 80,000. When the molecular weight is within the above range, good heat resistance and blocking resistance are obtained. Furthermore, the glass transition temperature of the cellulose resin is preferably 90°C to 200°C, more preferably 115°C to 180°C, and particularly preferably 140°C to 160°C. When the temperature is within the above range, the heat resistance and blocking resistance are good.

[0083] When the cellulose-based resin is a nitrocellulose resin, the nitrogen content of the nitrocellulose resin is preferably 10 to 13% by mass, and more preferably 10.7 to 12.2% by mass, of the total solid content of the nitrocellulose resin. When the nitrogen content is within this range, good heat resistance and blocking resistance are obtained.

[0084] The weight-average molecular weight of the nitrocellulose resin is preferably 3,000 to 40,000, more preferably 4,000 to 25,000, and even more preferably 5,000 to 15,000. When the molecular weight is within the above range, good blocking resistance is achieved. Examples of commercially available nitrocellulose resins include those manufactured by NOBEL (DHX3-5, DHX5-10, DHX8-13).

[0085] The mass ratio of urethane resin (A) to resin (B) in the first surface protective layer is preferably 20:80 to 95:5, more preferably 40:60 to 80:20, and even more preferably 55:45 to 70:30. Within the above range, excellent bending resistance and water abrasion resistance are achieved.

[0086] <Additives> The first surface protective layer may appropriately contain known additives. Examples of additives include pigment derivatives, dispersants, wetting agents, adhesion aids, leveling agents, defoamers, antistatic agents, trapping agents, antiblocking agents, waxes, isocyanate-based curing agents, and silane coupling agents. From the viewpoint of improving bending resistance and water friction resistance, it is preferable to include an isocyanate-based curing agent.

[0087] Isocyanate-based hardening agents Polyisocyanates and their modified compounds can be used as isocyanate-based curing agents. Specifically, biuret, isocyanurate, and adduct polyisocyanates are preferred, and diisocyanates are preferred as polyisocyanates, with aromatic diisocyanates such as tolylene diisocyanate; alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate and isophorone diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate; and aromatic aliphatic diisocyanates such as α,α,α',α'-tetramethylxylylene diisocyanate being preferred. Examples of commercially available isocyanate-based curing agents include 24A-100, 22A-75, TPA-100, TSA-100, TSS-100, TAE-100, TKA-100, P301-75E, E402-808, E405-70B, AE700-100, D101, D201, A201H (manufactured by Asahi Kasei), Mytec Y260A (manufactured by Mitsubishi Chemical Corporation), Coronate HX, Coronate HL, Coronate L (manufactured by Nippon Polyurethane Co., Ltd.), and Desmodul N75MPA / X (manufactured by Bayer AG). Among these, isophorone diisocyanate and hexamethylene diisocyanate are preferred, and hexamethylene diisocyanate is more preferred.

[0088] (Hexamethylene diisocyanate) As for the hexamethylene diisocyanate, the description and preferred form of (hexamethylene diisocyanate) described above in [First Surface Protective Layer] can be used by reference.

[0089] <First Overcoat Agent> The first overcoat agent contains urethane resin (A) and resin (B). From the viewpoint of increasing the cohesive strength of the coating film, it is preferable to further include the above-mentioned isocyanate-based curing agent. In addition, an organic solvent and the above-mentioned additives can be used.

[0090] The viscosity of the first overcoat agent is preferably 20 to 200 mPa·s from the viewpoint of printability and other factors.

[0091] Organic solvents Examples of organic solvents that can be used in the first overcoat agent include hydrocarbon-based solvents such as methylcyclohexane and ethylcyclohexane; ketone-based solvents such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone; ester-based solvents such as ethyl acetate, n-propyl acetate, and butyl acetate; and alcohol-based solvents such as methanol, ethanol, propanol, isopropanol (IPA), and butanol. The organic solvent may be selected appropriately considering the reduction of the amount of solvent remaining in the film after printing, and one type may be used alone or two or more types may be mixed. The content of the organic solvent is preferably 30 to 95% by mass, more preferably 50 to 90% by mass, and particularly preferably 70 to 85% by mass, based on 100% by mass of the first overcoat agent.

[0092] To improve the halftone reproduction quality during printing, it is preferable to use a glycol ether-based solvent. While there are no particular limitations on the glycol ether-based solvent, examples include ethylene glycol ether and propylene glycol ether. Among these, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether are preferred, and diethylene glycol monoethyl ether is more preferred. The glycol ether-based solvent is preferably present in an amount of 5 to 25% by mass, and particularly preferably 5 to 15% by mass, of 100% by mass of the organic solvent.

[0093] <Formation of the first surface protective layer> The first surface protective layer can be formed by printing on the paper substrate on the side opposite to the heat-seal layer using the first overcoat agent, and then removing the volatile components. Furthermore, if there is a printed layer on the paper substrate on the side opposite to the heat-seal layer, the first surface protective layer can be formed on the printed layer in the same way as when there is no printed layer. Printing methods include gravure printing, flexographic printing, and roll-kiss coating, with gravure printing being preferred. For example, in gravure printing, the first surface protective layer can be obtained by diluting the agent with a suitable viscosity and concentration as needed, supplying it to each printing unit either alone or in mixtures, applying it, and fixing the film by drying in an oven.

[0094] [Second surface protective layer] In this application, it is preferable that the packaging material further has a second surface protection layer. When a second surface protection layer is included, the layer configuration of the packaging material is in the order of heat seal layer, paper substrate, first surface protection layer, and second surface protection layer. The second surface protection layer contains resin (C) and can be formed by a second overcoat agent containing resin (C).

[0095] The application amount of the second surface protective layer is 1.5 to 12 g / m². 2 Preferably, it is 3-8.4 g / m 2 It is more preferable that the coating amount of the second surface protective layer be 1.5 g / m². 2 When the above conditions are met, the uniformity of the second surface protective layer is improved, resulting in good gloss, heat resistance, and blocking resistance, and the coating amount is 12 g / m². 2 In the following cases, the amount of residual solvent in the second surface protective layer decreases, resulting in improved blocking resistance.

[0096] <Resin (C)> The resin (C) contained in the second surface protective layer can include, for example, cellulose resins, polyamide resins, polylactic acid resins, urethane resins, vinyl chloride resins, vinyl chloride resins, vinyl chloride-acrylic copolymer resins, rosin resins, vinyl acetate resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, acrylic resins, urethane-acrylic resins, styrene resins, styrene-acrylic acid resins, styrene-allyl alcohol resins, styrene-maleic acid resins, maleic anhydride resins, maleic acid resins, rosin-modified maleic acid resins, cycloolefin resins, dammar resins, polyester resins, alkyd resins, terpene resins, phenol-modified terpene resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, polyacetal resins, silicone resins, and modified resins thereof. It is preferable that it contains cellulose resin, and more preferably that it contains both cellulose resin and polyamide resin.

[0097] Cellulose resin As for the cellulose resin, the description and preferred form of the <cellulose resin> described in the above-mentioned [First Surface Protective Layer] can be used.

[0098] Polyamide resin As described above, the second surface protective layer of the present invention preferably contains a polyamide resin in addition to a cellulose resin, from the viewpoint of improving blocking resistance. The polyamide resin is not particularly limited, but it is preferably a thermoplastic polyamide soluble in organic solvents, and polycondensates of polybasic acids and polyhydric amines are preferably used. In particular, polyamide resins containing a reaction product of an acid component containing polymerized fatty acids and aliphatic and / or aromatic polyamines are preferred, and those partially containing primary and secondary monoamines are more preferred.

[0099] The glass transition temperature of the polyamide resin is preferably 20 to 80°C, more preferably 30 to 70°C, and particularly preferably 40 to 60°C. When it is within the above range, gloss and heat resistance are improved. The weight-average molecular weight of the polyamide resin is preferably in the range of 2,000 to 70,000, and more preferably 5,000 to 30,000. When the weight-average molecular weight is 2,000 or more, heat resistance and blocking resistance are improved. When the weight-average molecular weight is 50,000 or less, gloss is good. Polyamide resins preferably have a softening point of 80 to 140°C, and more preferably 90 to 120°C. A softening point of 80°C or higher results in good heat resistance and blocking resistance. A softening point of 140°C or lower improves gloss. The softening point can be measured in accordance with JIS K 2207 (ring-ball method).

[0100] Examples of polybasic acids used as raw materials for polyamide resins include adipic acid, sebacic acid, azelaic acid, phthalic anhydride, isophthalic acid, suberic acid, glutaric acid, fumaric acid, pimelic acid, oxalic acid, malonic acid, succinic acid, maleic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid, trimellitic acid, and polymerized fatty acids. Among these, polymerized fatty acids are preferred. The polyamide resin preferably has a structure derived from polymerized fatty acids, and it is preferable that the polyamide resin contains 50% by mass or more of the structure derived from polymerized fatty acids. Here, polymerized fatty acids are those obtained by cyclization reactions of unsaturated fatty acids, and include monobasic fatty acids, dimerized polymerized fatty acids, and trimerized polymerized fatty acids. When polymerized fatty acids are used, those obtained by monobasic fatty acids containing unsaturated fatty acids or by ester polymerization thereof are preferred, and those obtained by polymerization of unsaturated fatty acids with 16 to 22 carbon atoms or their esters are preferred. Polymerized fatty acids may be used individually or two or more may be used in any proportion. Furthermore, the fatty acids constituting the polymerized fatty acids are preferably derived from natural oils such as soybean oil, palm oil, and rice bran oil, with oleic acid and linoleic acid being more preferred. Other basic acids can also be used in combination with monocarboxylic acids. Examples of monocarboxylic acids that can be used in combination include acetic acid, propionic acid, lauric acid, palmitic acid, benzoic acid, and cyclohexanecarboxylic acid.

[0101] Other amines include, for example, polyamines and primary or secondary monoamines. Examples of the polyamines mentioned above include aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, and methylaminopropylamine; aliphatic polyamines such as diethylenetriamine and triethylenetetramine; alicyclic polyamines such as cyclohexylenediamine and isophoronediamine; aromatic aliphatic polyamines such as xylylenediamine; and aromatic polyamines such as phenylenediamine and diaminodiphenylmethane. Examples of primary and secondary monoamines include n-butylamine, octylamine, diethylamine, monoethanolamine, monopropanolamine, diethanolamine, and dipropanolamine. From the viewpoint of adhesion, blocking resistance, oil resistance, and heat resistance, polyamide resins preferably have hydroxyl groups in their molecules, and it is preferable to use alkanolamines as primary or secondary monoamine components.

[0102] Commercially available polyamide resins that can be used include, for example, the Vegichem Green series (manufactured by Tsukuno Foods Co., Ltd.) and the Newmide series (manufactured by Harima Chemicals Co., Ltd.).

[0103] In the second surface protective layer, the mass ratio of cellulose resin to polyamide resin is preferably 99:1 to 15:85, more preferably 50:50 to 15:85, and particularly preferably 30:70 to 15:85. Within this range, excellent gloss, heat resistance, and blocking resistance are achieved.

[0104] <Additives> The second surface protective layer may contain any additives such as plasticizers, amide waxes, hydrocarbon waxes, and chelating crosslinking agents, and preferably contains at least one selected from the group consisting of plasticizers, amide waxes, and hydrocarbon waxes.

[0105] Plasticizer From the viewpoint of blocking resistance, the second surface protective layer of the present invention preferably further contains a plasticizer. As a plasticizer, one that has excellent compatibility with the resin contained in the second surface protective layer and has low volatility is preferably used. For example, it is preferable to include at least one selected from the group consisting of citrate esters, phthalates, phosphate esters, trimetates, aliphatic dibasic acid esters, glycol ethers, sulfonate amides, and castor oil.

[0106] Examples of citrate esters include acetyltrialkyl citrates such as triethyl citrate, acetyltriethyl citrate, tri-n-butyl citrate, acetyltri-n-butyl citrate, and acetyl-2-ethylhexyl citrate. The alkyl group preferably has 2 to 12 carbon atoms, with acetyltri-n-butyl citrate and acetyltriethyl citrate being more preferred. Examples of phthalate esters include dialkyl phthalates such as bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, and diundecyl phthalate. The alkyl group preferably has 2 to 12 carbon atoms, with diisononyl phthalate and diisodecyl phthalate being more preferred. Examples of phosphate esters include tricresyl phosphate, triphenyl phosphate, tributyl phosphate, and other phosphate esters, with tributyl phosphate being preferred. Examples of trimetate esters include trialkyl trimetates such as tri-2-ethylhexyl trimetate, trioctyl trimetate, and triisononyl trimetate. The alkyl group preferably has 2 to 12 carbon atoms, with tri-2-ethylhexyl trimetate being more preferred. As for the aliphatic dibasic acid ester, it is preferable that the alkyl group contained in the aliphatic dibasic acid ester has 2 to 12 carbon atoms, and it is more preferable that it is a fatty acid dialkyl ester. Examples of fatty acid dialkyl esters include adipic acid esters and sebacate acid esters, and it is preferable that they are bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis(2-ethylhexyl) sebacate, diisononyl sebacate, and diisodecyl sebacate. Examples of sulfonamide compounds include N-butylbenzenesulfonamide and N-ethyltoluenesulfonamide. Examples of glycol ethers include diethylene glycol monobutyl ether and diethylene glycol monoethyl ether.

[0107] In the present invention, the plasticizer content in the second surface protective layer is preferably 0.1 to 15% by mass, more preferably 3 to 12% by mass, and particularly preferably 5 to 9% by mass. When the content is within the above range, the blocking resistance is improved.

[0108] Amied Wax From the viewpoint of blocking resistance, the second surface protective layer of the present invention preferably further contains amide wax. The amide wax is a fatty acid amide, preferably one having a fatty acid residue and an amide group. It is believed that the fatty acid amide orients on the surface of the second protective layer after printing, exhibiting slipperiness and improving blocking resistance. This explanation is based on technical considerations and does not limit the invention in any way.

[0109] Suitable examples of fatty acid amides include monoamides, substituted amides, bisamides, methylolamides, and esteramides, and it is preferable that the fatty acid amide is at least one selected from the group consisting of monoamides, substituted amides, and bisamides.

[0110] The melting point of the fatty acid amide is preferably between 50°C and 150°C. Examples of monoamides with melting points between 50°C and 150°C include lauric acid amide (melting point 87°C), palmitic acid amide (melting point 100°C), stearic acid amide (melting point 101°C), behenic acid amide (melting point 110°C), hydroxystearate amide (melting point 107°C), oleic acid amide (melting point 75°C), and erucic acid amide (melting point 81°C). Substitutional amides with melting points of 50°C to 150°C include N-oleyl palmitamide (melting point 68°C), N-stearyl stearate amide (melting point 95°C), N-stearyl oleamide (melting point 67°C), N-oleyl stearate amide (melting point 74°C), and N-stearyl erucamide (melting point 69°C). Examples of bisamides with a melting point of 50°C to 150°C include methylenebisstearate (melting point 142°C), ethylenebisstearate (melting point 145°C), ethylenebishydroxystearate (melting point 145°C), ethylenebisbehenamide (melting point 142°C), hexamethylenebisstearate (melting point 140°C), hexamethylenebisbehenamide (melting point 142°C), and hexamethylenehydroxystearate ( Examples include ethylenebisoleamide (melting point 135°C), ethylenebiserucamide (melting point 119°C), ethylenebiserucamide (melting point 120°C), hexamethylenebisoleamide (melting point 110°C), N,N'-distearyladipamide (melting point 141°C), N,N'-distearylsebacinamide (melting point 136°C), N,N'-dioleyladipamide (melting point 118°C), and N,N'-dioleylsebacinamide (melting point 113°C). Examples of methylolamides with a melting point of 50°C to 150°C include methylol stearate amide (melting point 110°C). Examples of esteramides with a melting point of 50°C to 150°C include stearamidoethyl stearate (melting point 82°C). In particular, from the viewpoint of improving blocking resistance, those with a molecular weight of 200 to 800 are preferred. More preferably, those with a molecular weight of 250 to 700 are preferred.

[0111] The fatty acids constituting the fatty acid amide are preferably saturated fatty acids having 12 to 22 carbon atoms and / or unsaturated fatty acids having 16 to 25 carbon atoms, and more preferably saturated fatty acids having 16 to 18 carbon atoms and / or unsaturated fatty acids having 18 to 22 carbon atoms. Particularly preferred saturated fatty acids are lauric acid, palmitic acid, stearic acid, behenic acid, and hydroxystearic acid, and particularly preferred unsaturated fatty acids are oleic acid and erucic acid. In particular, fatty acid amides consisting of at least one fatty acid selected from the group consisting of palmitic acid, stearic acid, behenic acid, hydroxystearic acid, oleic acid, and erucic acid are preferred, at least one fatty acid amide selected from the group consisting of palmitic acid amide, erucic acid amide, and ethylenebisoleic acid amide are more preferred, and ethylenebisoleic acid amide is especially preferred.

[0112] The amide wax content is preferably 0.1 to 22.5% by mass, more preferably 0.1 to 15% by mass, and even more preferably 0.1 to 7.5% by mass. When the content is within the above range, the blocking resistance is improved.

[0113] Hydrocarbon waxes The second surface protective layer preferably contains hydrocarbon wax. The inclusion of hydrocarbon wax improves the water- and abrasion-resistant properties of the second surface protective layer. The hydrocarbon wax is preferably hydrocarbon wax particles with a hardness (penetration) of 0.5 to 12. Examples of hydrocarbon waxes include polyethylene wax, Fischer-Tropsch wax, paraffin wax, microstarin wax, and polypropylene wax. Among these, hydrocarbon wax containing polyethylene wax is preferred. In the overcoat agent, the hydrocarbon wax can be used in liquid or particulate form, but particulate form is preferred. The average particle size of the hydrocarbon wax particles is preferably 0.3 to 10 μm, and more preferably 0.8 to 7 μm. The content of hydrocarbon wax particles in the second surface protective layer is preferably 0.1 to 10% by mass, and more preferably 0.5 to 7% by mass.

[0114] Chelate crosslinking agent The second surface protective layer may contain a chelating crosslinking agent. Including a chelating crosslinking agent improves the heat resistance of the second surface protective layer. Examples of chelating crosslinking agents include titanium chelate and zirconium chelate. Examples of titanium chelates include titanium alkoxides such as tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, tetramethyl titanate, and tetrastearyl titanate, as well as triethanolamine titanate, titanium acetylacetate, titanium tetraacetylacetonate, tetraisopropoxytitanium, titanium ethylacetoacetate, titanium lactate, octylene glycol titanate, n-butyl phosphate titanium, and propanediokistitanium bis(ethylacetylacetate). Examples of zirconium chelates include zirconium propionate and zirconium acetylacetate. From the viewpoint of heat resistance, oil resistance, and PVC blocking resistance, it is preferable to use a chelating crosslinking agent that does not generate acetylacetone after the crosslinking reaction.

[0115] The content of the chelating crosslinking agent in the second surface protective layer is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass. When the content is 0.1% by mass or more, heat resistance, oil resistance, and blocking resistance are improved, and when it is 5% by mass or less, the storage stability of the second overcoat agent is excellent.

[0116] <Second Overcoat Agent> The second overcoat agent may contain resin (C), and may also contain an organic solvent and the aforementioned additives.

[0117] The viscosity of the second overcoat agent is preferably 20 to 200 mPa·s from the viewpoint of printability and other factors.

[0118] Organic solvents The organic solvent can be provided by referring to the description and preferred form of the "organic solvent" described above in the [first surface protective layer] section.

[0119] <Formation of the second surface protective layer> The second surface protective layer can be formed by printing with the second overcoat agent on the printed layer if one exists, or on the first surface protective layer if one does not exist, and then removing the volatile components. Printing methods include gravure printing, flexographic printing, and roll-kiss coating, with gravure printing being preferred. For example, in gravure printing, the second surface protective layer can be obtained by diluting the agent with a suitable viscosity and concentration as needed, supplying it to each printing unit either alone or in a mixture, applying it, and fixing the film by drying in an oven.

[0120] The packaging material may further have a printed layer coated with printing ink. In this application, "printing ink" refers to an ink containing a coloring agent such as a pigment.

[0121] [Print layer] The printed layer is located between the paper substrate and the first surface protective layer and preferably contains a colorant and a resin (D). The printed layer can be formed with a printing ink containing a colorant and a resin (D), and the formation method can be appropriately selected from known printing methods such as gravure printing and flexographic printing, with gravure printing being preferred. The viscosity of the printing ink is preferably 20 to 200 mPa·s from the viewpoint of printability and other factors.

[0122] The amount of coating applied to the printing layer is 0.1 to 12 g / m². 2Preferably, it is 0.3 to 8.4 g / m 2 It is more preferable that the amount be 0.5 to 3.6 g / m 2 It is particularly preferable that this is the case. In the present invention, not only a single printed layer but also a layer in which multiple printed layers are superimposed can be used as a printed layer, and printed layers with different hues can be arbitrarily combined.

[0123] <Resin (D)> The resin (D) content in the printed layer is preferably 10 to 70% by mass, and more preferably 30 to 50% by mass, of the total mass of the printed layer. Examples of the above resin (D) include cellulose resins, polyamide resins, polylactic acid resins, urethane resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-acrylic copolymer resins, rosin resins, vinyl acetate resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, acrylic resins, urethane-acrylic resins, styrene resins, styrene-acrylic acid resins, styrene-allyl alcohol resins, styrene-maleic acid resins, maleic anhydride resins, maleic acid resins, rosin-modified maleic acid resins, cycloolefin resins, dammar resins, polyester resins, alkyd resins, terpene resins, phenol-modified terpene resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, polyacetal resins, silicone resins, and modified resins thereof. From the viewpoint of improving water resistance and friction resistance, cellulose resins, vinyl chloride-acrylic copolymer resins, and vinyl chloride-vinyl acetate copolymer resins are preferred, but the resin is not limited to these. These may be used individually or in combination of two or more types.

[0124] <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 15 to 50% by mass, of the total mass of the printed layer.

[0125] 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.

[0126] 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 83, 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, These are 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, and CI Pigment Black 7. These may be used individually or in combination of two or more types.

[0127] (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.

[0128] <Additives> The printed layer may further contain additives such as pigment dispersants, isocyanate curing agents, chelating crosslinking agents, hydrocarbon waxes, matting agents, fine powder silica such as vapor-phase silica, wet-process silica, organically treated silica, and alumina-treated silica, fatty acid amide waxes, defoaming agents, leveling agents, plasticizers, infrared absorbers, ultraviolet absorbers, and flame retardants, to the extent that they do not impair the effects of the present invention.

[0129] Pigment dispersant From the viewpoint of colorability, the printed layer preferably contains a pigment dispersant. As the pigment dispersant, surfactants such as anionic, nonionic, cationic, and amphoteric surfactants can be used.

[0130] Chelate crosslinking agent From the viewpoint of heat resistance, the printed layer preferably contains a chelating crosslinking agent. The description of the chelating crosslinking agent in the section on "Chelate Crosslinking Agents" in the [Overcoat Agents] section above can be used as a reference. The content of the chelating crosslinking agent in the printed layer is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass. When the content is within this range, excellent heat resistance and blocking resistance are obtained.

[0131] Hydrocarbon waxes The printed layer preferably contains hydrocarbon wax from the viewpoint of blocking resistance. The hydrocarbon wax can be described in the section on "Hydrogen Wax" in the above-mentioned [Surface Protective Layer]. In the printing layer, hydrocarbon wax can be used in liquid or particulate form, but particulate form is preferred. The average particle size is preferably 0.3 to 10 μm, and more preferably 0.8 to 7 μm. The content of the hydrocarbon wax particles in the printing layer is preferably 0.1 to 10% by mass, more preferably 0.5 to 7% by mass. When the content is within the above range, excellent blocking resistance is achieved.

[0132] Plasticizer The printed layer preferably contains a plasticizer from the viewpoint of blocking resistance. The plasticizer plays a role in promoting the volatilization of organic solvents even in small amounts. The description of the plasticizer can be referred to in the section on "Plasticizers" in the above-mentioned [Surface Protective Layer]. The printed layer in the present invention preferably contains at least one plasticizer selected from the group consisting of castor oil, glycol ether, aliphatic dibasic acid ester, and tributyl acetylcitrate, with castor oil being more preferred. The plasticizer content in the printed layer is preferably 0.1 to 15% by mass, more preferably 5 to 15% by mass, and even more preferably 11 to 15% by mass. When the content is within the above range, the resistance to blocking is excellent.

[0133] <Printing Ink> The printed layer is preferably formed by a printing ink containing the above-mentioned colorant and the above-mentioned resin (C).

[0134] <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.

[0135] <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.

[0136] [Paper base material] The paper substrate is not particularly limited, and known types can be used. Examples of such paper substrates include medium-grade paper, fine-grade paper, newsprint, various coated papers, backing paper, impregnated paper, cardboard and art paper, cast paper, kraft paper, coated cardboard, ivory paper, card stock, cup paper, cast paper, light-shielding paper, and surface-treated paper substrates thereof. Furthermore, the above paper substrate may also contain a barrier resin. The basis weight of the paper substrate is preferably 50 to 150 g / m². 2 More comfortably 55-120 g / m 2 More preferably 60-90 g / m 2 That is the case.

[0137] <Barrier resin> Examples of barrier resins included in the paper substrate include cellophane, vinyl alcohol resin, ethylene-vinyl alcohol copolymer resin, paraffin resin, acrylic resin, rosin resin, and epoxy resin, with vinyl alcohol resin and ethylene-vinyl alcohol copolymer resin being preferred. These may be used individually or in combination of two or more types.

[0138] [Heat seal layer] The heat seal layer in this invention comprises at least one selected from the group consisting of acrylic resin, olefin resin, and urethane resin (E), and is located on the side of the paper substrate opposite to the side having the first surface protective layer. The heat seal layer can be formed by a heat sealant comprising at least one selected from the group consisting of acrylic resin, olefin resin, and urethane resin, and the formation method can be appropriately selected from known printing methods such as gravure printing, flexographic printing, and roll kiss coating, with gravure printing being preferred. The coating amount of the heat seal layer is 1 to 18 g / m². 2 It is 3-12 g / m 2 Preferably, it is 4-8 g / m 2 It is particularly preferable that the above range is achieved. When it is within the above range, heat sealability and blocking resistance are good.

[0139] The heat-seal layer may further contain known resins such as vinyl resin.

[0140] The resin content in the heat seal layer is preferably 80 to 100% by mass, and more preferably 90 to 100% by mass, of 100% by mass of the heat seal layer. When the content is within this range, the heat sealability is good.

[0141] <Acrylic resin> Acrylic resin is a resin containing constituent units derived from (meth)acrylic monomer. It is preferable that the acrylic resin has carboxyl groups and other acidic groups. The acid value of the acrylic resin is preferably 20 to 120 mgKOH / g, more preferably 30 to 100 mgKOH / g, and particularly preferably 40 to 80 mgKOH / g. When the acid value of the acrylic resin is 20 mgKOH / g or higher, it exhibits good recyclability, and when it is 120 mgKOH / g or lower, it exhibits good blocking resistance. The glass transition temperature of the acrylic resin is preferably -40 to 10°C, more preferably -30 to 5°C, and particularly preferably -20 to 0°C. When the glass transition temperature of the acrylic resin is within the above range, it exhibits good blocking resistance and heat sealability.

[0142] Suitable acrylic resins include homopolymers of (meth)acrylic monomers, copolymers of (meth)acrylic monomers and acid monomers, and copolymers of ethylene and (meth)acrylic monomers. From the viewpoint of blocking resistance, copolymers of ethylene and (meth)acrylic monomers are preferred.

[0143] Examples of monomers containing the (meth)acrylic monomer include alkyl ester compounds of (meth)acrylic acid such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, decyl (meth)acrylate, and lauryl (meth)acrylate. (meth)acrylamide derivatives containing at least one N-substituted methylol group, such as N-methylol(meth)acrylamide, Aminoalkyl esters of (meth)acrylic acid such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dipropylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, dipropylaminopropyl (meth)acrylate, etc. (Meth)acrylic acid mono or diesters of glycols such as diethylene glycol and dipropylene glycol, Hydroxyalkyl ester compounds of (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate. Acrylic acid, methacrylic acid, Styrene, styrene derivatives such as α-methylstyrene, Examples include vinyl compounds having acidic groups such as maleic acid and itaconic acid. From the standpoint of heat-sealability, acrylic resins having carboxyl groups and / or hydroxyl groups are preferred, and if the acrylic resin has hydroxyl groups, it is preferable that the monomer constituting the acrylic resin contains a hydroxyalkyl ester compound of (meth)acrylic acid.

[0144] Acrylic resins can be commercially available products, such as BASF's JONCRYL PDX7356, PDX-7326, PDX-7430; Seikoh PMC's PE-1126, JE-1113, KE1148; and Japan Coating Resin's AC-3100.

[0145] <Olefin resin> Examples of olefin resins include polypropylene resin, polyethylene resin, and ethylene-vinyl acetate copolymer resin, but polyethylene resin is preferred. These may be used individually or in combination of two or more types.

[0146] Polyethylene resin The minimum film-forming temperature for polyethylene resin is preferably 40 to 120°C, and more preferably 60 to 100°C. Within this range, good heat-sealability is achieved.

[0147] The glass transition temperature of polyethylene resin is preferably -60 to 20°C, more preferably -25 to 5°C, and particularly preferably -20 to -10°C. When the temperature is within the above range, the heat sealability is good.

[0148] For example, the polyethylene resin used can be the ChemiPearl series (manufactured by Mitsui Chemicals, Inc.).

[0149] Measurement of the minimum film formation temperature In this application, the minimum film formation temperature was determined in accordance with JIS K 6828-1:2003, using a TP-801MFT tester manufactured by Tester Sangyo Co., Ltd.

[0150] (Urethane resin (E)) The urethane resin (E) may be of the form and preferred range of <urethane resin (A)> as described above in [First surface protective layer].

[0151] <Additives> The heat seal layer may further contain any additives such as defoamers, emulsifiers, preservatives, plasticizers, amide waxes, hydrocarbon waxes, and chelating crosslinking agents, and it is preferable that it contains defoamers and / or emulsifiers.

[0152] <Heat sealant> The heat sealant of this application comprises an acrylic resin and / or an ethylene-vinyl acetate copolymer resin, and further comprises a solvent. It may also contain the above-mentioned additives. From the viewpoint of environmental impact, the heat sealant is preferably aqueous. From the viewpoint of printability, the viscosity of the heat sealant is preferably 20 to 200 mPa·s.

[0153] Antifoaming agent In the heat sealant of the present invention, it is preferable to include an antifoaming agent. When an antifoaming agent is included, the smoothness of the heat seal layer is improved, resulting in good heat seal strength. Examples of antifoaming agents include silicone-based antifoaming agents and non-silicone-based antifoaming agents, and from the viewpoint of antifoaming properties, silicone-based antifoaming agents are preferred. The content of the antifoaming agent in the heat seal layer is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass, and particularly preferably 0.1 to 0.3% by mass, based on 100% by mass of the heat seal layer.

[0154] A commercially available defoaming agent may be used; for example, BYK-024, BYK-025, BYK-028, etc., manufactured by BYK Corporation can be used.

[0155] "emulsifier" In the heat sealant of this application, it is preferable to include an emulsifier. When an emulsifier is included, the solubility in water is improved, which improves the long-term stability of the heat sealant. Examples of emulsifiers include vinyl alcohol resin, ethylene-vinyl alcohol copolymer resin, nonionic surfactant, cationic surfactant, anionic surfactant, etc., and from the viewpoint of long-term stability, vinyl alcohol resin and cationic surfactant are preferred. The content of the emulsifier in the heat seal layer is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass, and particularly preferably 0.1 to 0.3% by mass, based on 100% by mass of the heat seal layer.

[0156] <Formation of heat seal layer> The heat-seal layer can be formed, for example, by printing on the paper substrate surface opposite the first surface protective layer using a heat-seal agent, and then drying and removing the volatile components. Gravure printing and flexographic printing are preferred printing methods. For example, in gravure printing, the heat-seal layer can be obtained by diluting the agent with a suitable viscosity and concentration as needed, supplying it to each printing unit either alone or in a mixture, applying it, and fixing the film by drying it in an oven.

[0157] (Gravure printing) Gravure version In gravure printing, the gravure plate is a cylindrical metal plate into which recesses of each color are formed by engraving, etching, or laser. There are no restrictions on the use of engraving or laser, and the settings can be arbitrarily determined according to the design. Line screen resolutions ranging from 80 to 250 are used as appropriate, with higher line screens allowing for finer printing.

[0158] Gravure printing press In a gravure printing press, one printing unit is equipped with the gravure plate and doctor blade. There are multiple printing units, and each unit has an oven drying unit. Printing is performed by rotary press using a roll printing method. The type of plate and doctor blade are selected as appropriate, and can be chosen according to the specifications.

[0159] The packaging material may also have a barrier layer.

[0160] [Barrier layer] The barrier layer exists to control the transmission of substances that need to be blocked, such as light, magnetism, and various gases, through the packaging material, and contains barrier components. The barrier layer can be formed by vapor deposition, lamination, die-casting, or by coating and drying in liquid form using the aforementioned barrier components. Examples of barrier components include barrier resins such as aluminum, silica, alumina, polyvinylidene chloride resin, polyamide resin, polyvinyl alcohol resin, ethylene-vinyl alcohol copolymer resin, barrier nylon resin (MXD), etc., or metal compounds such as aluminum, silica, and alumina. The barrier layer may be a single layer or a multi-layer structure, and may contain two or more compounds in one layer.

[0161] The following are suitable examples of laminated packaging material configurations in this application. In the following examples, " / " represents the boundary between each layer. Heat seal layer / Paper substrate / First surface protective layer Heat seal layer / Paper substrate / First surface protection layer / Second surface protection layer Heat seal layer / Paper substrate / Printing layer / First surface protective layer Heat seal layer / Paper substrate / Printing layer / First surface protection layer / Second surface protection layer Heat seal layer / Barrier layer / Paper substrate / First surface protective layer Heat seal layer / Barrier layer / Paper substrate / First surface protection layer / Second surface protection layer Heat seal layer / Barrier layer / Paper substrate / Printing layer / First surface protective layer Heat seal layer / Barrier layer / Paper substrate / Printing layer / First surface protection layer / Second surface protection layer Heat seal layer / Paper substrate / Barrier layer / First surface protection layer Heat seal layer / Paper substrate / Barrier layer / First surface protection layer / Second surface protection layer Heat seal layer / Paper substrate / Barrier layer / Printing layer / First surface protection layer Heat seal layer / Paper substrate / Barrier layer / Printing layer / First surface protection layer / Second surface protection layer

[0162] <Amount of paper base material in packaging materials> The paper base material content in the total amount of packaging material is preferably 50 to 99% by mass or more, more preferably 65 to 95% by mass or more, and particularly preferably 80 to 90% by mass.

[0163] <Packaging bag> The packaging material in this invention is cut to a predetermined size, and the edges are heat-sealed with the heat-seal layers joined 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 packaging bag can be formed by folding a single sheet of packaging material and heat-sealing the edges, or by heat-sealing two or more sheets of packaging material. Alternatively, a packaging bag can be formed by heat-sealing all openings after packaging the contents. This type of packaging bag can be widely used as packaging for food, pharmaceuticals, and other products. [Examples]

[0164] 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.

[0165] <Synthesis Example 1> Synthesis of Urethane Resin Solution PU1 232.6 parts of a polyester polyol (number average molecular weight: 2000, hereinafter referred to as "MPOA," having two hydroxyl groups per molecule), a condensate of adipic acid and 2-methyl-1,3-propanediol, 4.2 parts of 1,4-butanediol (hereinafter referred to as "1,4-BD"), 50.5 parts of isophorone diisocyanate (hereinafter referred to as "IPDI," molecular weight: 222.29, having two NCO groups per molecule), and 71.8 parts of ethyl acetate were reacted under a nitrogen stream at 80°C for 4 hours to obtain a solution containing a prepolymer. Next, 10.2 parts of isophoronediamine (hereinafter "IPDA," molecular weight: 170.30, containing two primary amino groups per molecule), 2.5 parts of dimethylaminopropylamine (hereinafter "DMAPA," molecular weight: 102.201, containing one primary amino group and one tertiary amino group per molecule), and 628.2 parts of a mixed solvent of ethyl acetate / 2-propanol (hereinafter "IPA") = 50 / 50 (mass ratio) were mixed. The above prepolymer solution was then gradually added to this mixture at 40°C, and the mixture was reacted at 80°C for 1 hour to obtain a solution of urethane resin A1 with a non-volatile content of 30%, a total amine value of 7.5 mgKOH / g, a combined amine value of primary and secondary amines of 2.9 mgKOH / g, a hydroxyl value of 0 mgKOH / g, and a weight-average molecular weight of 52500.

[0166] <Synthesis Examples 2-8> Synthesis of Urethane Resins PU2-8 Urethane resins PU2-8 were obtained using the same method as in Synthesis 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. • NPA: A polyester polyol (number-average molecular weight: 2000) which is a condensate of adipic acid and neopentyl glycol. • PMPA: A polyester polyol (number average molecular weight: 2000) that is a condensate of adipic acid and 3-methyl-1,5-pentanediol. • PEG: Polyethylene glycol (number-average molecular weight: 1000, contains 2 hydroxyl groups per molecule) • PPG: Polypropylene glycol (number average molecular weight: 1000 and 2000; contains 2 hydroxyl groups per molecule) IBPA: Iminobispropylamine (molecular weight: 131.22, contains two primary amino groups and one secondary amino group) • 2EtAm: 2-aminoethanol (molecular weight: 61.08, containing one primary amino group and one hydroxyl group)

[0167] [Table 1]

[0168] <Preparation Example 1> Preparation of Nitrocellulose Resin Solution NC1 59.6 parts of nitrocellulose nc1 (NV. 70% (solvent: isopropyl alcohol), weight-average molecular weight: 10,000, viscosity at a solution concentration of 25% by mass: 2 seconds, glass transition temperature: 155°C) were mixed and dissolved in 33.6 parts of ethyl acetate and 33.6 parts of isopropyl alcohol to obtain an NV. 30% nitrocellulose resin solution (NC1).

[0169] <Preparation Example 2> Preparation of Nitrocellulose Resin Solution NC2 Nitrocellulose resin solution NC2 was obtained using the same method as in Preparation Example 1, except that the raw materials listed below were used. • (NC2) Nitrocellulose nc2 (NV. 70% (solvent: isopropyl alcohol), viscosity at 25% by mass solution concentration: 1.2 seconds, glass transition temperature: 147°C)

[0170] <Preparation Example 3> Preparation of Cellulose Acetate Butyrate Resin Solution CAB1 59.6 parts of cellulose acetate butyrate CAB1 (manufactured by Tomoe Engineering Co., Ltd., product name CAB-381-0.1, NV. 70% (solvent: isopropyl alcohol), glass transition temperature: 123°C, weight-average molecular weight 20,000, viscosity at a solution concentration of 25% by mass: 0.1 seconds) were mixed and dissolved in 33.6 parts of ethyl acetate and 33.6 parts of isopropyl alcohol to obtain a 30% NV cellulose acetate butyrate resin solution (CAB1).

[0171] <Preparation Example 4> Preparation of Polyamide Resin Solution PA1 Thirty parts of polyamide resin PA1 (manufactured by Tsukuno Foods Industry Co., Ltd., product name Vegichem Green 725, NV. 100%, glass transition temperature 50°C, weight-average molecular weight 8,000) and seventy parts of isopropyl alcohol were charged and dissolved under a nitrogen stream at 50°C for 2 hours to obtain a polyamide resin solution (PA1) with an NV. of 30%.

[0172] <Manufacturing Example 1> Manufacturing of the first overcoat agent X1 45 parts of ethyl acetate / isopropyl alcohol mixed solvent, 17.9 parts of urethane resin PU1, 17.9 parts of urethane resin PU4, and 19.3 parts of vinyl chloride-acrylic copolymer resin PVC1 (manufactured by Tomoe Industrial Co., Ltd., Vinnol E15 / 40A, hydroxyl value: 59 mg KOH / g, weight-average molecular weight: 45000, glass transition temperature: 69°C) were added and stirred to obtain the first overcoat agent X1.

[0173] <Manufacturing Examples 2-17, Comparative Manufacturing Examples 1 and 2> Manufacturing of the first overcoat agent X2-19 The first overcoat agents X2-19 were obtained using the same method as in Production Example 1, except that the raw materials and mixing ratios listed in Table 2 were used. The properties of the raw materials used are as follows. • Vinyl chloride-vinyl acetate copolymer resin PVC2 (manufactured by Nisshin Chemical Industry Co., Ltd., Solvine TA5R, hydroxyl value: 154 mg KOH / g, weight-average molecular weight: 28000, glass transition temperature: 78℃) • Polyvinyl butyral PVB1 (BL-5, manufactured by Sekisui Chemical Co., Ltd., weight-average molecular weight: 40,000, glass transition temperature: 65°C)

[0174] [Table 2]

[0175] <Manufacturing Examples 18-25> Second Overcoat Agent X20-27 The second overcoat agents X20-27 were obtained using the same method as in Manufacturing Example 1, except that the raw materials and mixing ratios listed in Table 3 were used.

[0176] [Table 3]

[0177] <Manufacturing Example 26> Preparation of Heat Sealant HS1 91.7 parts of olefin resin emulsion OF1 (manufactured by Mitsui Chemicals, product name Chemipearl S300, solvent: water, NV=30), 8.2 parts of water / isopropyl alcohol mixed solvent (mass ratio 1:1), and 0.1 parts of BYK-024 (manufactured by BYK, defoamer) were added and stirred to obtain heat sealant HS1.

[0178] <Manufacturing Examples 27-29> Preparation of Heat Sealant HS2-4 Heat sealants HS2-4 were obtained using the same method as in Preparation Example 19, except that the raw materials and mixing ratios listed in Table 4 were used. The properties of the raw materials used are as follows. Acrylic resin emulsion AC1 (manufactured by Seikoh PMC, JE-1113, acid value: 42 mg KOH / g, glass transition temperature: -24℃, solvent: water, NV. = 30%)

[0179] [Table 4]

[0180] The following examples illustrate how to manufacture the packaging material.

[0181] <Measurement of coating amount for each layer> From the obtained packaging material, the portion with the layered structure shown below was cut into 10 cm squares, its weight was measured, and the coating amount was calculated using the following formula. (Formula 4) Coating amount of heat seal layer (g / m²) 2 ) = (Weight of heat-sealed layer / weight of paper substrate) - (Weight of paper substrate) (Formula 5) Coating amount of the printed layer (g / m²) 2 ) = (Weight of heat-seal layer / paper substrate / printed layer) - (Weight of heat-seal layer / paper substrate) (Formula 6) Application amount of the first surface protective layer (g / m²) 2 ) = (Weight of heat-seal layer / paper substrate / printed layer / first surface protective layer) - (Weight of heat-seal layer / paper substrate / printed layer) (Formula 7) Coating amount of the second surface protective layer (g / m²) 2 ) = (Weight of heat-seal layer / paper substrate / printed layer / first surface protection layer / second surface protection layer) - (Weight of heat-seal layer / paper substrate / printed layer / first surface protection layer) Furthermore, the above formula can be applied even if the packaging material does not have a printed layer.

[0182] <Example 1> Manufacturing of packaging material P1 100 parts of printing ink (Ecocolor HR23 yellow, manufactured by Toyo Ink Co., Ltd., yellow ink; details of the contained resin are described later) were diluted with a mixed solvent of ethyl acetate:isopropyl alcohol = 7:3 (mass ratio), and the viscosity was adjusted to 15 seconds at 25°C in a Zahn Cup #3 (manufactured by Rigosha). Also, 100 parts of the second overcoat agent X15 were diluted with a mixed solvent of ethyl acetate:isopropyl alcohol = 7:3 (mass ratio), and the viscosity was adjusted to 15 seconds at 25°C in a Zahn Cup #3 (manufactured by Rigosha). Furthermore, 100 parts of the first overcoat agent X1 were diluted with a mixed solvent of ethyl acetate:isopropyl alcohol = 7:3 (mass ratio), and the viscosity of each was adjusted to 30 seconds at 25°C in a Zahn Cup #3 (manufactured by Rigosha). Then, 3 parts of curing agent 1 (hexamethylene diisocyanate, trimer, isocyanurate type, NV.=50%) were added and stirred. Kraft paper: Kraft paper made from unbleached kraft pulp (manufactured by Nippon Paper Industries, double-sided kraft K, basis weight 70g / m²) 2 A heat sealant HS1 was printed onto a roll of material (width: 100 cm) using an automatic bar coater (Matsuo Sangyo Co., Ltd., K303 Multi Coater) at a printing speed of 10 m / min and bar coater grit #4. The heat sealant layer was then formed by drying at an oven temperature of 80°C for 10 minutes to evaporate the solvent. The coating amount of the heat sealant layer was 5 g / m². 2 That was the case. Next, diluted printing ink was printed onto the opposite side of the heat-sealed layer of the paper substrate using an automatic bar coater (Matsuo Sangyo Co., Ltd., K303 Multi Coater) at a printing speed of 10 m / min and bar coater number #2. The printed layer was then formed by drying at an oven temperature of 80°C for 10 minutes to evaporate the solvent. The coating amount of the printed layer was 2 g / m². 2 That was the case. Next, a first overcoat agent, diluted and with hardener 1 added, was printed onto the printed layer using an automatic bar coater (Matsuo Sangyo Co., Ltd., K303 multi-coater) at a printing speed of 10 m / min and bar coater grit #4. The coating was then dried at an oven temperature of 80°C for 10 minutes to evaporate the solvent and form a film. Finally, the first surface protective layer was formed by printing and drying again on the film under the same conditions. The amount of the first surface protective layer applied was 12.5 g. Finally, the diluted second overcoat agent was printed onto the first surface protective layer using an automatic bar coater (Matsuo Sangyo Co., Ltd., K303 Multi Coater) at a printing speed of 10 m / min and bar coater grit #4. The second surface protective layer was formed by drying at an oven temperature of 80°C for 10 minutes to evaporate the solvent, thereby obtaining a packaging material P1 having the following configuration: heat seal layer / paper substrate / printed layer / first surface protective layer / second surface protective layer. The amount of the second surface protective layer applied was 4 g.

[0183] The resins contained in the above-mentioned Eco Color HR23 yellow printing ink are as follows: • Nitrocellulose resin solution NC3 (weight-average molecular weight: 11,000, viscosity at 25.0% solution concentration: 3 seconds) • Urethane resin solution PU7 (weight-average molecular weight: 50,000, glass transition temperature: -20°C, amine value undetectable (less than 0.1 mg KOH / g)) The non-volatile content ratio of NC3 and PU7 is NC3:PU7 = 90:10.

[0184] <Examples 2-45, Comparative Examples 1-6> Manufacturing of Packaging Materials P2-51 Except for using the heat sealant, first overcoat agent, and second overcoat agent shown in Tables 5 and 6, packaging materials P2 to 51 having the same configuration were prepared using the same procedure as in Example 1.

[0185] [Table 5]

[0186] [Table 5]

[0187] [Table 5]

[0188] [Table 6]

[0189] [Evaluation of Packaging Material] The packaging materials P1 to P51 obtained in Examples 1 to 45 and Comparative Examples 1 to 6 were evaluated according to the methods described below. The results are shown in Table 5 and Table 6. For the measurement of residual solvent content, a portion of the packaging material does not have a heat seal layer, and this portion is not used in the following evaluations.

[0190] <Folding Resistance> The obtained packaging material was cut into a 100 mm square, folded such that the heat seal layer surfaces overlapped each other, and a load was applied to the folded portion under the condition of 1 kg / m 2 for 5 seconds. The folded portion was cut into a 3 mm square, the cut cross-section was observed by SEM, and evaluation was performed according to the following criteria. Grades A, B and C are within the range with no practical problems. <<Evaluation Criteria>> A. No cracks occurred at all in the cross-section of the coating film. B. Slight cracks occurred in the cross-section of the coating film. C. Many cracks occurred in the cross-section of the coating film. D. The coating film was completely fractured.

[0191] <Water-Resistant Rubbing Resistance> The obtained packaging material was cut into a size of 25 mm×150 mm, and the following test (1) was carried out using a Gakushin-type friction fastness tester manufactured by Tester Sangyo Co., Ltd. If water impregnation into the paper base material could not be confirmed after the test, test (2) was subsequently carried out. If water impregnation into the paper base material could not be confirmed after carrying out test (2), test (3) was subsequently carried out, and water friction resistance was evaluated according to the following criteria. Note that grades A, B, and C fall within the range with no practical problems. <<Test Conditions>> Test (1): Load 200 g, 100 reciprocations, counterpart paper: a Kanakin cloth dripped with 5 drops of water Test (2): Load 500 g, 200 reciprocations, counterpart paper: a Kanakin cloth dripped with 5 drops of water Test (3): Load 1000 g, 200 reciprocations, counterpart paper: a Kanakin cloth dripped with 5 drops of water <<Evaluation Criteria>> A. After carrying out test (3), water impregnation into the paper base material could not be confirmed. B. After carrying out test (3), water impregnation into the paper base material was confirmed. C. After carrying out test (2), water impregnation into the paper base material was confirmed. D. After carrying out test (1), water impregnation into the paper base material was confirmed.

[0192] <Blocking Resistance> Two pieces of the obtained packaging material were cut into 40 mm squares, the heat seal layer surface of one packaging material piece was completely overlapped with the second surface protective layer surface of the other packaging material piece (if there is no second surface protective layer, the first surface protective layers were overlapped with each other), under conditions of a temperature of 40°C, a humidity of 80%RH, and a load of 100 N / cm 2 and compression-bonded under the environment. After standing for 24 hours, the two stacked packaging materials were peeled apart, the peeling state of the printed layer was visually observed, and evaluated according to the following criteria. Note that grades A, B, and C fall within the range with no practical problems. <<Evaluation Criteria>> A. The transfer amount of the printed layer to the heat seal layer surface is less than 5 area%. B. The transfer amount of the printed layer to the heat seal layer surface is 5 area% or more and less than 10 area%. C. The transfer amount of the printed layer to the heat seal layer surface is 10 area% or more and less than 25 area%. D. The amount of print layer transferred to the heat seal layer surface is 25% or more by area.

[0193] <Heat-sealable> 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: 10 mm from the bend, heater temperature: 160℃, seal pressure: 2 kg / cm 2 , 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: 100 mm / min Evaluation Criteria A. The heat seal strength is 3.5N or higher. B. The heat seal strength is 2.5N or more and less than 3.5N. C. The heat seal strength is 1.0 N or more and less than 2.5 N. D. The heat seal strength is less than 1.0 N.

[0194] From the results above, Comparative Examples 1 and 3 had poor heat sealability because they lacked a heat seal layer. Comparative Examples 2 and 3 had a coating amount of 3.0 g / m² for the first surface protective layer. 2 Because the amount was less than 20 g / m², the bending resistance and water abrasion resistance were poor. Comparative Example 4 had a coating amount of 20 g / m². 2 Because it was excessive, it had poor blocking resistance. Comparative Example 5 did not meet the requirements for water friction resistance and blocking resistance because the first surface protective layer did not contain resin (B). Comparative Example 6 did not contain urethane resin (A) because it had poor bending resistance and water friction resistance. On the other hand, the embodiment has a heat-seal layer, and the first surface protective layer contains urethane resin (A) and resin (B), and the coating amount of the layer is 3 to 20 g / m². 2 Therefore, it exhibited good resistance to bending, water and abrasion, blocking, and heat sealing. In particular, the heat seal layer contains polyethylene resin, and the coating amount of the heat seal layer is 4-8 g / m². 2 In the first surface protective layer, the total amine value of urethane resin (A1) is 7-9 mgKOH / g, the amine value of urethane resin (A2) is 11-13 mgKOH / g, resin (B) is vinyl chloride-acrylic copolymer resin PVC1, the mass ratio of urethane resin (A) to resin (B) is 55:45-70:30, and the coating amount of the first surface protective layer is 10-14 g / m². 2 The elastic modulus of the first surface protective layer is 2.5 × 10 8 ~5×10 8 The Pa (Pa) and loss factor are 0.35 to 0.55. The second surface protective layer contains nitrocellulose resin and polyamide resin, with a mass ratio of nitrocellulose resin to polyamide resin of 30:70 to 15:85, and the coating amount of the second surface protective layer is 3 to 8.4 g / m². 2 Examples 1, 27, 30, 39, and 40 demonstrated excellent bending resistance, water abrasion resistance, blocking resistance, and heat sealability.

Claims

1. A packaging material having, in sequence, a heat-seal layer, a paper substrate, and a first surface protective layer, The first surface protective layer comprises a urethane resin (A) and a resin other than urethane resin (A) (B), The urethane resin (A) contains structural units derived from polyester, The resin (B) includes a vinyl resin and / or a cellulose resin. The coating amount of the first surface protective layer is 3 to 20 g / m². ２ It is a packaging material.

2. The packaging material according to claim 1, wherein the resin (B) other than the urethane resin (A) is a vinyl resin, and the vinyl resin is at least one selected from the group consisting of vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, and polyvinyl acetal resin.

3. The elastic modulus of the first surface protective layer at 25°C, as measured according to JIS K 7244-4, is 1.0 × 10⁻⁶. ８ ~1.5 x 10 ９ The packaging material according to claim 1 or 2, wherein the material is Pa.

4. The packaging material according to claim 1 or 2, wherein the loss coefficient of the first surface protective layer at 25°C, as measured according to JIS K 7244-4, is 0.1 to 0.

7.

5. The packaging material according to claim 1 or 2, wherein the heat seal layer comprises at least one selected from the group consisting of polyolefin resin, acrylic resin, and urethane resin (E).

6. The packaging material according to claim 1 or 2, wherein the urethane resin (A) comprises a urethane resin (A1) with a total amine value (mgKOH / g) of 1 or more and less than 10, and a urethane resin (A2) with a total amine value (mgKOH / g) of 10 or more and 20 or less.

7. The packaging material according to claim 1 or 2, wherein the packaging material further comprises a second surface protection layer, and the layer configuration of the packaging material is in the order of a heat seal layer, a paper substrate, a first surface protection layer, and a second surface protection layer.

8. The packaging material according to claim 7, wherein the second surface protective layer comprises a cellulose resin.

9. The packaging material according to claim 8, wherein the second surface protective layer further comprises a polyamide resin.

10. A method for manufacturing a packaging material having, in sequence, a heat-seal layer, a paper substrate, and a first surface protective layer, A process of forming a heat seal layer on one side of a paper substrate by gravure printing a heat seal agent, A first overcoat agent containing urethane resin (A) and a resin other than urethane resin (B) is gravure printed onto the other side of a paper substrate, with a coating amount of 3 to 20 g / m². ２ The process of forming the first surface protective layer, Includes, A method for manufacturing a packaging material in which the urethane resin (A) contains structural units derived from polyester.

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