Resin composition, coating liquid, film, coated article, laminate, and packaging material

Abstract

The present invention relates to a resin composition comprising, with respect to 100 parts by mass of a modified starch (A), 10-40 parts by mass of a water-soluble polymer (B), and 0.05-10 parts by mass of at least one carboxylic acid compound (C) that is selected from the group consisting of acetic acid (C1), a carboxylic acid (C2) having 4-10 carbon atoms, and a metal salt (C3) of a carboxylic acid having 2-10 carbon atoms.

Description

Specification Title of the Invention: Resin Composition, Coating Liquid, Film, Coated Article, Laminate, and Packaging Material Technical Field [0001 I The present invention relates to a resin composition used for food packaging containers and the like, a coating liquid containing the resin composition, a film made of the resin composition, a laminate including a layer made of the resin composition, and a packaging material including the film or the laminate. Background Art

[0002] A resin composition containing modified starch and polyvinyl alcohol is widely used as a material for containers and the like for packaging food because it is biodegradable and has excellent gas barrier properties. For example, there are containers and the like manufactured using a coated article obtained by coating paper or a film with the resin composition, and high gas barrier properties are required for the coated article. Usually, the coated article is manufactured by coating a melt of the resin composition discharged from the die outlet of a melt extruder onto paper or a film conveyed by a take-up machine (for example, Patent Document 1). Prior Art Documents Patent Documents

[0003] Patent Document 1: International Publication No. 2019 / 03077 Summary of the Invention Problems to be Solved by the Invention

[0004] However, manufacturers who do not own melt extruders have attempted to produce these films using coating machines, which are easier to handle. However, coating solutions prepared by dissolving conventional resin compositions containing modified starch and polyvinyl alcohol in solvents such as water have very high viscosity. Therefore, even when preparing coating solutions with typical solid content concentrations, the coating properties are poor, making it difficult to form a uniformly thick coating film, and thus preventing the production of films suitable for food packaging containers. Furthermore, when preparing coating solutions with reduced solid content concentrations to achieve low viscosity and uniform coating, a coating film of sufficient thickness cannot be obtained in a single application; multiple applications are required to obtain the desired thickness. Additionally, the high water content of the coating solution leads to longer drying times after coating, posing a problem for industrial productivity. Moreover, even when manufacturing films and laminates using melt extruders, there is a demand for lower viscosity resin compositions. [0005I Accordingly, an object of the present invention is to provide a resin composition that exhibits low viscosity suitable for coating even when the solid content concentration is increased, and that can form films, laminates, etc. with excellent oxygen barrier properties by coating, and that has excellent processability. Furthermore, an object of the present invention is to provide a film made of the resin composition, a laminate including a layer made of the resin composition, and a packaging material including the film or the laminate. Means for solving the problem

[0006] As a result of diligent research to solve the above problems, the present inventors have discovered that by adding a specific amount of a specific carboxylic acid compound (C) to a resin composition consisting of modified starch (A) and a water-soluble polymer (B), the viscosity of the coating solution is significantly reduced when the resin composition is dissolved in a solvent such as water to prepare a coating solution, and a low-viscosity coating solution suitable for coating can be obtained even when the solid content concentration is increased, thus completing the present invention.

[0007] In other words, the present invention is as follows: [1] A resin composition comprising 10 to 40 parts by mass of water-soluble polymer (B) per 100 parts by mass of modified starch (A), and 0.05 to 10 parts by mass of at least one carboxylic acid compound (C) selected from the group consisting of acetic acid (C1), carboxylic acids having 4 to 10 carbon atoms (C2), and metal salts of carboxylic acids having 2 to 10 carbon atoms (C3). [2] The resin composition according to [1], wherein the average amylose content of the modified starch (A) is 50% by mass or more. [3] The resin composition according to [1] or [2], wherein the modified starch (A) is at least one selected from the group consisting of etherified starch, esterified starch, cationized starch, and crosslinked starch. [4] A resin composition according to any one of [1] to [3], wherein the water-soluble polymer (B) is a polyvinyl alcohol-based resin. [5] The resin composition according to any one of [1] to [4], wherein the carboxylic acid compound (C) comprises 0.05 to 10 parts by mass of acetic acid (C1) and / or a metal salt (C3) of a carboxylic acid having 2 to 1 carbon atoms, per 100 parts by mass of modified starch (A). [6] The resin composition according to any one of [1] to [4], wherein the carboxylic acid compound (C) contains 0.05 to 10 parts by mass of a metal salt (C3) of a carboxylic acid having 2 to 1 carbon atoms, per 100 parts by mass of modified starch (A). A coating liquid comprising a resin composition described in any of [1] to [6] and a solvent. [8] A film comprising the resin composition described in any of [1] to [6]. [9] A laminate comprising a layer comprising the resin composition described in any of [1] to [6] and one or more layers (X) different from the said layer.

[10] The laminate according to [9], wherein one or more layers (X) are selected from the group consisting of a base layer, an adhesive layer, a resin layer, a metal layer, a metal vapor deposition layer, an inorganic vapor deposition layer, a paper layer, and a sealant layer. [1 1] The laminate according to [9], wherein layer (X) includes at least a substrate layer, the substrate layer being a layer of paper or film.

[0012] A laminate according to any one of [9] to

[11] , wherein layer (X) includes at least a base layer (X1) and a further layer (X2). Packaging material comprising the film described in [1 3] [8], or the laminate described in any of [9] to [1 2]. Effects of the invention [0008I The resin composition of the present invention has a low viscosity when dissolved in a solvent such as water to prepare a coating solution. Therefore, even when the solid content concentration is increased, it exhibits a low viscosity suitable for coating and has excellent processability. Furthermore, films and laminates containing a layer made of the resin composition of the present invention have excellent oxygen barrier properties. Therefore, films, coatings, and laminates manufactured using the resin composition of the present invention can be suitably used as packaging materials for food products. Brief explanation of the drawing

[0009] [Figure 1] This is a schematic diagram of the twin-screw extruder used in the embodiment. Modes for carrying out the invention

[0010] The embodiments of the present invention will be described in detail below. However, this is not intended to limit the present invention to the following embodiments.

[0011] [Resin composition] The resin composition of the present invention is a resin composition comprising 100 parts by mass of modified starch (A), 10 to 4 parts by mass of a water-soluble polymer (B), and 5 to 1 parts by mass of at least one carboxylic acid compound (C) selected from the group consisting of acetic acid (C1), carboxylic acids having 4 to 1 carbon atoms (C2), and metal salts of carboxylic acids having 2 to 1 carbon atoms (C3).

[0012] The present inventors have found that when a resin composition contains 10 to 4 parts by mass of a water-soluble polymer (B) and 0.05 to 1 part by mass of the above-mentioned specific carboxylic acid compound (C) per 100 parts by mass of modified starch (A), the viscosity of the solution when dissolved in a solvent such as water to prepare a coating solution can be significantly reduced while maintaining excellent oxygen barrier properties, and the composition exhibits excellent processability. This is presumed to be because the above-mentioned specific carboxylic acid compound (C) has the function of weakening the interaction between modified starch (A).

[0013] Modified starch (A) > The modified starch (A) is preferably at least one selected from the group consisting of, for example, etherified starch, esterified starch, cationized starch, and cross-linked starch.

[0014] Examples of starches include those derived from cassava, maize, potatoes, sweet potatoes, sago, tapioca, sorghum, beans, bracken, lotus, water chestnut, wheat, rice, oats, arrowroot, peas, etc. Among these, starches derived from maize and cassava are preferred, and high-amylose starches derived from maize are even more preferred. Starches can be used alone or in combination of two or more types. [0015! Examples of etherified starch include alkyl etherified starch such as methyl etherified starch; carboxyalkyl etherified starch such as carboxymethyl etherified starch; and hydroxyalkyl etherified starch such as etherified starch having a hydroxyalkyl group with 2 to 6 carbon atoms. Allyl etherified starch can also be used.

[0016] Examples of esterified starches include esterified starches having structural units derived from carboxylic acids, such as esterified starches having structural units derived from acetic acid; esterified starches having structural units derived from dicarboxylic acid anhydrides, such as esterified starches having structural units derived from maleic anhydride, esterified starches having structural units derived from phthalic anhydride, and esterified starches having structural units derived from octenylsuccinic acid anhydride; and esterified starches having structural units derived from oxoacids, such as nitrate esterified starch, phosphate esterified starch, and urea phosphate esterified starch. Other examples include xanthogenic acid esterified starch and acetoacetate esterified starch.

[0017] Examples of cationized starch include reaction products of starch and 2-diethylaminoethyl chloride, and reaction products of starch and 2,3-epoxypropyltrimethylammonium chloride.

[0018] Examples of cross-linked starches include formaldehyde-cross-linked starch, epichlorohydrin-cross-linked starch, phosphate-cross-linked starch, and acrolein-cross-linked starch.

[0019] Modified starch (A) is preferably at least one selected from the group consisting of etherified starch having a hydroxyalkyl group with 2 to 6 carbon atoms and esterified starch having structural units derived from dicarboxylic acid anhydrides, from the viewpoint of film-forming properties during coating production. More preferably, it is at least one selected from the group consisting of hydroxyethyl etherified starch, hydroxypropyl etherified starch, hydroxybutyl etherified starch, esterified starch having structural units derived from maleic anhydride, esterified starch having structural units derived from phthalic anhydride, and esterified starch having structural units derived from octenyl succinic anhydride. Modified starch (A) can be used alone or in combination of two or more. In this specification, the number of carbon atoms mentioned before "starch" represents the number of carbon atoms in the group substituted for one hydroxyl group in the starch (a group formed by modifying one hydroxyl group in the starch). For example, etherified starch having a hydroxyalkyl group with 2 to 5 carbon atoms indicates that the hydroxyalkyl group formed by modifying one hydroxyl group in the starch has 2 to 5 carbon atoms. [0020I Etherified starch having a hydroxyalkyl group with 2 to 6 carbon atoms may be obtained by the reaction of starch with an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide. The average number of hydroxyl groups used for modification is preferably 0.05 to 2 per glucose unit in the starch. [0021I Modified starch (A) preferably has an average amylose content of 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and particularly preferably 70% by mass or more. When the average amylose content is above the lower limit of the above, it is easier to improve oxygen barrier properties, biodegradability and moldability. The amylose content in modified starch (A) is usually 90% by mass or less. In this specification, the amylose content can be measured, for example, by the iodine colorimetric method described in "Starch 50 No. 4158-163 (1998) J". The average amylose content refers to the amylose content of the one type of modified starch used when only one type is used, and is the weighted average of the amylose content of the two or more types of modified starches when two or more types of modified starches are used. Therefore, for example, when two or more types of modified starches are used and the average amylose content is 50% by mass or more, it is possible that modified starches with an amylose content of less than 50% by mass are included. [0022I Modified starch (A) preferably has a water content of 5 to It is 1.5% by mass.

[0023] Modified starch (A) can also be a commercially available product. Representative examples of commercially available modified starch (A) include hydroxypropyl etherified starch manufactured by ingredion, such as ECOFILM (registered trademark) and Natina I1658 (registered trademark).

[0024] Water-soluble polymer (B) > The water-soluble polymer (B) is not particularly limited as long as it is a water-soluble polymer compound, but among these, polyvinyl alcohol-based resins are preferred. Examples of polyvinyl alcohol-based resins include ethylene-vinyl alcohol copolymers, polyvinyl alcohol-based resins, and polyvinyl acetal-based resins, and among these, polyvinyl alcohol-based resins are preferred from the viewpoint of easily improving stretchability. In this specification, polyvinyl acetal-based resin refers to a resin containing 85 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more of structural units derived from vinyl acetal based on the amount of total structural units, and polyvinyl alcohol-based resin refers to a resin containing 85 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more of structural units derived from vinyl alcohol based on the amount of total structural units.

[0025] When a polyvinyl alcohol-based resin is used as the water-soluble polymer (B), the degree of saponification of the polyvinyl alcohol-based resin is preferably 80-99.8 mol%. When the degree of saponification of the polyvinyl alcohol-based resin is within the above range, the oxygen barrier properties are easily enhanced. The degree of saponification is more preferably 85 mol% or higher, and even more preferably 88 mol% or higher. In this specification, the degree of saponification refers to the mole fraction of hydroxyl groups relative to the total of hydroxyl groups and ester groups in the polyvinyl alcohol-based resin. [0026I Polyvinyl alcohol-based resins may further contain other monomer units besides vinyl alcohol units. Examples of other monomer units include monomer units derived from ethylenically unsaturated monomers.Ethylene-unsaturated monomers include ethylene, propylene, n-butene, isobutylene, 1-hexene and other α-olefins; acrylic acid and its salts; unsaturated monomers having an acrylic acid ester group; methacrylic acid and its salts; unsaturated monomers having a methacrylic acid ester group; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts (e.g., quaternary salts); methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidopropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts (e.g., quaternary salts); methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, Vinyl ethers such as dodecyl vinyl ether, stearyl vinyl ether, 2,3-diacetoxy-1-vinyloxypropane; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidenes such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid and their salts or esters; vinylsilyl compounds such as vinyltrimethoxysilane, isopropenyl acetate; vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl carlylate, vinyl laurylate, vinyl palmitate, Examples include vinyl ester monomers such as vinyl stearate, vinyl oleate, and vinyl benzoate. Furthermore, monomer units derived from unsaturated monomers that have not been saponified are also included in the aforementioned other monomer units.The content of other monomer units is preferably 10 mol% or less, and more preferably 5 mol% or less. [0027I The method for producing polyvinyl alcohol resins is not particularly limited. For example, one method involves polymerizing a vinyl alcohol monomer and optionally other monomers, and then saponifying the resulting polymer to convert it into vinyl alcohol units. Polymerization methods include batch polymerization, semi-batch polymerization, continuous polymerization, and semi-continuous polymerization. Known polymerization methods include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Known methods can be applied to saponify the polymer. For example, this can be done when the polymer is dissolved in alcohol or aqueous alcohol. The alcohol used in this case is preferably a lower alcohol such as methanol or ethanol. [0028I The polyvinyl alcohol-based resin has a viscosity of 1 mPa•s or more, more preferably 2 mPa•s or more, even more preferably 3 mPa•s or more, preferably 45 mPa•s or less, and more preferably 35 mPa•s or less, as measured in accordance with JIS Z 8803, for a 4% aqueous solution at 20 °C. When the viscosity of the polyvinyl alcohol-based resin is within the above range, it is easier to improve oxygen barrier properties and film strength during film formation. The viscosity of the polyvinyl alcohol-based resin can be measured using a viscometer, for example, by the method described in the examples. [0029I The content of water-soluble polymer (B) is 10 to 40 parts by mass per 100 parts by mass of modified starch (A). If the content of water-soluble polymer (B) is less than 10 parts by mass, the oxygen barrier properties tend to decrease, and if it exceeds 40 parts by mass, the film strength during film formation tends to decrease. The content of water-soluble polymer (B) is 10 parts by mass or more, preferably 13 parts by mass or more, and 40 parts by mass or less, preferably 35 parts by mass or less. When the content of water-soluble polymer (B) is within the above range, it is easy to increase oxygen barrier properties and film strength. [0030I Carboxylic Acid Compound (C) >The carboxylic acid compound (C) to be incorporated into the resin composition of the present invention is at least one carboxylic acid compound selected from the group consisting of acetic acid (C1), carboxylic acids having 4 to 1 carbon atoms (C2), and metal salts of carboxylic acids having 2 to 1 carbon atoms (C3). By incorporating a specific carboxylic acid compound (C), a significant decrease in viscosity can be produced when the resin composition of the present invention is dissolved in a solvent such as water to prepare a coating solution. From the viewpoint of reducing the viscosity of the coating solution containing the resin composition, the number of carbon atoms in the carboxylic acid having 4 to 1 carbon atoms (C2) is preferably 4 to 8, more preferably 4 to 6. From a similar viewpoint, the number of carbon atoms in the metal salts of carboxylic acids having 2 to 1 carbon atoms (C3) is preferably 2 to 8, more preferably 2 to 6, and even more preferably 3 to 5. Therefore, from the viewpoint of reducing viscosity when the resin composition is dissolved in a solvent such as water to prepare a coating solution, the carboxylic acid compound (C) is preferably selected from the group consisting of acetic acid (C1), carboxylic acids having 4 to 8 carbon atoms (C2), and metal salts of carboxylic acids having 2 to 8 carbon atoms (C3), more preferably selected from the group consisting of acetic acid (C1), carboxylic acids having 4 to 6 carbon atoms (C2), and metal salts of carboxylic acids having 2 to 6 carbon atoms (C3), even more preferably selected from the group consisting of acetic acid (C1) and metal salts of carboxylic acids having 2 to 8 carbon atoms (C3), and even more preferably metal salts of carboxylic acids having 2 to 8 carbon atoms (C3). The resin composition of the present invention may contain one type of carboxylic acid compound (C), two types of carboxylic acid compounds (C), or three types of carboxylic acid compounds (C). Furthermore, the resin composition of the present invention may contain only one compound as the carboxylic acid compound (C), or it may contain two or more compounds. [0031 ! Examples of carboxylic acids (C2) having 4 to 1 carbon atoms include aliphatic carboxylic acids having 4 to 1 carbon atoms, polycarboxylic acids having 4 to 1 carbon atoms, unsaturated carboxylic acids having 4 to 1 carbon atoms, and aromatic carboxylic acids having 4 to 1 carbon atoms. Examples of aliphatic carboxylic acids having 4 to 1 carbon atoms include butyric acid, valeric acid, caproic acid, enantic acid, caprylic acid, pelargonic acid, and capric acid. Examples of polycarboxylic acids having 4 to 1 carbon atoms include malonic acid, succinic acid, maleic acid, fumaric acid, adipic acid, and citric acid. Examples of unsaturated carboxylic acids having 4 to 1 carbon atoms include sorbic acid, acrylic acid, and methacrylic acid. Aromatic carboxylic acids having 4 to 1 carbon atoms include benzoic acid, phthalic acid, terephthalic acid, and isophthalic acid. [0032! The metal species of the metal salt (C3) of a carboxylic acid having 2 to 1 carbon atoms is not particularly limited, but is preferably a divalent metal such as magnesium, calcium, or zinc. Therefore, the metal salt (C3) of a carboxylic acid having 2 to 1 carbon atoms is preferably a calcium salt, magnesium salt, or zinc salt of a carboxylic acid having 2 to 1 carbon atoms, and more preferably a calcium salt or zinc salt. Examples of metal salts (C3) of carboxylic acids having 2 to 1 carbon atoms include metal salts of aliphatic carboxylic acids having 2 to 1 carbon atoms, metal salts of polyhydric carboxylic acids having 2 to 1 carbon atoms, metal salts of unsaturated carboxylic acids having 2 to 1 carbon atoms, and metal salts of aromatic carboxylic acids having 2 to 1 carbon atoms.

[0033] Examples of metal salts of aliphatic carboxylic acids having 2 to 1 carbon atoms include magnesium acetate, calcium acetate, zinc acetate, calcium propionate, magnesium propionate, zinc propionate, calcium butyrate, magnesium butyrate, calcium valerate, calcium caproate, calcium enanthinate, calcium caprylate, calcium pelargonate, and calcium caprate.

[0034] Examples of metal salts of polyvalent carboxylic acids having 2 to 10 carbon atoms include calcium oxalate, magnesium oxalate, zinc oxalate, calcium malonate, calcium succinate, calcium maleate, magnesium fumarate, calcium adipate, magnesium citrate, and the like.

[0035] Examples of metal salts of unsaturated carboxylic acids having 2 to 10 carbon atoms include calcium sorbate, magnesium acrylate, zinc acrylate, calcium methacrylate, magnesium methacrylate, and the like.

[0036] Examples of metal salts of aromatic carboxylic acids having 2 to 10 carbon atoms include calcium benzoate, zinc benzoate, calcium phthalate, zinc phthalate, calcium terephthalate, magnesium isophthalate, and the like. [0037I Carboxylic acid compound (C) is more preferably selected from the group consisting of calcium acetate, zinc acetate, calcium propionate, calcium sorbate, and citric acid, even more preferably selected from the group consisting of calcium acetate, zinc acetate, calcium propionate, and calcium sorbate, and even more preferably selected from the group consisting of zinc acetate and calcium propionate, from the viewpoint of processability such as viscosity reduction when preparing a coating solution by dissolving a resin composition in a solvent such as water. Further, carboxylic acid compound (C) is preferably a metal salt (C3) of a carboxylic acid having 2 to 10 carbon atoms from the viewpoints of safety and corrosion avoidance of manufacturing equipment.

[0038] The content of the carboxylic acid compound (C) is 0.05 to 10 parts by mass, preferably 0.1 to 10 parts by mass, more preferably 0.15 to 10 parts by mass, still more preferably 0.2 to 8 parts by mass, still more preferably 0.3 to 7 parts by mass, particularly preferably 0.4 to 6 parts by mass, and most preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the modified starch (A). When the content of the carboxylic acid compound (C) is less than 0.05 parts by mass, insufficient viscosity reduction occurs when the resin composition of the present invention is dissolved in a solvent such as water to prepare a coating solution. On the other hand, when the content exceeds 10 parts by mass, the film strength of the film or coating obtained from the resin composition of the present invention decreases. The content of acetic acid (C1), carboxylic acids having 4 to 10 carbon atoms (C2), and metal salts of carboxylic acids having 2 to 10 carbon atoms (C3) is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 10 parts by mass, still more preferably 0.15 to 10 parts by mass, still more preferably 0.2 to 8 parts by mass, still more preferably 0.3 to 7 parts by mass, and most preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the modified starch (A).

[0039] <Other components> The resin composition of the present invention may further contain oxalic acid, propionic acid, fatty acids having 11 to 22 carbon atoms, and / or their fatty acid salts, as long as the effects of the present invention are not impaired. Examples of the fatty acids having 11 to 22 carbon atoms and their fatty acid salts include stearic acid, calcium stearate, sodium stearate, palmitic acid, lauric acid, myristic acid, linoleic acid, behenic acid, etc. Among these, from the viewpoint of processability, stearic acid, calcium stearate, and sodium stearate are preferable. The fatty acids having 11 to 22 carbon atoms and their fatty acid salts can be used alone or in combination of two or more. [0040I When the resin composition of the present invention contains a fatty acid having 11 to 22 carbon atoms and / or a fatty acid salt thereof, the content in the resin composition is preferably 0.01 to 3% by mass, more preferably 0.03 to 2% by mass, and even more preferably 0.1 to 1% by mass, relative to the mass of the resin composition. When the content of fatty acids having 11 to 22 carbon atoms and / or a fatty acid salt thereof is within the above range, it tends to be advantageous in terms of processability.

[0041] The resin composition of the present invention may further contain clay, if necessary. Examples of clays include synthetic or natural layered silicate clays such as montmorillonite, bentonite, byderite, mica, hectorite, saponite, nontronite, souconite, vermiculite, reddikite, magadite, chenyaite, stevensite, and volkonskite. Clays can be used individually or in combination of two or more types.

[0042] When the resin composition of the present invention contains clay, the clay content in the resin composition is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and even more preferably 0.5 to 2% by mass, relative to the mass of the resin composition. When the clay content is within the above range, it tends to be advantageous in terms of transparency and strength.

[0043] The resin composition of the present invention may further contain, as necessary, additives such as fillers, processing stabilizers, weather-resistant stabilizers, colorants, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, flame retardants, other thermoplastic resins, lubricants, fragrances, defoamers, deodorizers, bulking agents, release agents, mold release agents, reinforcing agents, crosslinking agents, antifungal agents, preservatives, and crystallization rate retarders. [0044I In the resin composition of the present invention, the total content of modified starch (A), water-soluble polymer (B), and carboxylic acid compound (C) is preferably 60% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, and preferably 100% by mass or less, based on the total mass of the resin composition. When the total content of components (A), (B), and (C) is within the above range, the film-forming properties of the resin composition of the present invention, as well as the oxygen barrier properties and film strength of the films and laminates obtained from the resin composition, are easily enhanced.

[0045] [Method for producing resin composition] The method for producing the resin composition of the present invention is not particularly limited, but for example, it can be produced by a method comprising the steps of: (1) mixing modified starch (A), a water-soluble polymer (B), and a carboxylic acid compound (C) to obtain a mixture; (2) extruding the mixture; and (3) cooling and drying the extruded mixture.

[0046] Step (1) is a step of mixing at least the modified starch (A), the water-soluble polymer (B), and the carbon 2 to 1〇 carboxylic acid and / or carboxylic acid compound (〇), and optionally other components, such as the carbon 11 to 22 fatty acids and / or fatty acid salts thereof, the clay, and the additives, can be mixed together within a range that does not impair the effects of the present invention.

[0047] The mixing in step (1) is usually carried out using an extruder. In the extruder, each component is subjected to shear stress by a screw and heated by applying external heat to the barrel while being mixed homogeneously. Each component may be introduced directly into the extruder, or the components may be pre-mixed using a mixer or pulverizer before being introduced into the extruder.

[0048] A single-screw or twin-screw extruder can be used as the extruder. The twin-screw extruder may be either co-rotating or counter-rotating. The screw diameter may be, for example, 20 to 150 mm, and the ratio of the extruder length (L) to the screw diameter (D) (L / D ratio) may be, for example, 20 to 50. The screw rotation speed is preferably at least 80 rpm, more preferably at least 100 rpm. The extrusion pressure is preferably at least 5 bar (0.5 MPa), more preferably at least 10 bar (1.0 MPa). [0049I In step (1), a cooking process is performed by heating to a temperature preferably greater than 120°C and 180°C or less, more preferably between 160°C and 180°C or less. Here, the cooking process is a process of crushing and gelling the starch granules. Heating can be performed by applying heat from the outside to the barrel of the extruder. The target temperature can be reached by applying gradually changing temperatures to each barrel. Performing the cooking process at a temperature greater than 120°C is advantageous in terms of processability. [0050I In step (1), water may be introduced in the relatively early stages of the extruder, before the above heating temperature is reached, for example, when the temperature is below 100°C. The modified starch (A) can be cooked by a combination of moisture, heat and shear stress to gelatinize it. In addition, by introducing water separately, the water-soluble polymer (B) can be dissolved, the resin composition can be softened, and the modulus and brittleness can be reduced. [0051I By exhausting from the barrel, foaming can be prevented and moisture can be removed. Also, the residence time in the extruder can be set according to the temperature profile and screw speed, and is preferably 1 to 2.5 minutes. [0052I In step (2) extruding the mixture, the molten mixture that has been pushed through the extruder while being melt-kneaded is extruded from the die. The die temperature is preferably 85 to 300 °C, more preferably 90 to 250 °C. [0053I In step (3) of cooling and drying the extruded mixture (molten material), the extruded mixture (molten material) can be cooled and dried in any shape such as a film or pellet. [0054I When the mixture is extruded into a film, the mixture can be extruded from a film forming die and then cooled and dried while being wound up on a take-up roller. It is preferable to cool the mixture between the die and the roller to prevent it from sticking to the roller. A forming roll may be installed between the die and the roller. The forming roll may be made of, for example, rubber, resin, or metal. For drying, the roll may be heated and dehumidified air may be supplied during winding. In the case of the blown-tube method, the dehumidified air can be used to inflate the film as it exits the die. Talc can also be entrained in the airflow to prevent the film from blocking. [0055I When extruding a mixture into strands, the strands can be formed into pellets by extruding them from a multi-hole strand nozzle and cutting them with a rotary cutter. To prevent the pellets from sticking together, vibration can be applied periodically or continuously, and moisture in the pellets can be removed using hot air, dehumidified air, or an infrared heater.

[0056] The resin composition of the present invention may be in any shape, such as pellets or films. When the resin composition of the present invention is in pellet form, it is preferable because it can be used as is as a raw material when preparing a coating solution, as described below. When the resin composition of the present invention is in film form, it is preferable to crush the film before using it, as it takes time to dissolve in the solvent if used as is as a raw material when preparing a coating solution.

[0057] As described above, it is also possible to manufacture a film made from the resin composition of the present invention by extruding the molten resin composition of the present invention from a film molding die to form a film. In this case, the present invention also has the effect of reducing the melt viscosity of the resin composition, and by having a reduced melt viscosity in the extruder, effects such as reduced torque during extrusion and uniformity of the resulting film are achieved. The film manufactured in this way can be used as is as a material with excellent oxygen barrier properties to constitute packaging materials, or a laminate can be manufactured by bonding the film to a base layer and, if necessary, an adhesive layer.

[0058] This specification also discloses a resin composition (A) that is different from the resin composition of the present invention. Resin composition (A) is a resin composition that contains 10 to 4 parts by mass of a water-soluble polymer (B) and 0.05 to 1 part by mass of at least one carboxylic acid compound (YC) selected from the group consisting of oxalic acid (YC1) and propionic acid (YC2), per 100 parts by mass of modified starch (A), wherein the content of the above-mentioned carboxylic acid compound (C) is not 0.05 to 1 part by mass. The content of the carboxylic acid compound (YC) in the resin composition (A) is 0.05 to 1.0 parts by mass per 100 parts by mass of modified starch (A), preferably 0.1 to 10 parts by mass, more preferably 0.2 to 10 parts by mass, even more preferably 0.5 to 8 parts by mass, and even more preferably 1 to 5 parts by mass. [0059I The resin composition (⸫) can be applied to coating liquids (coating liquids comprising the resin composition (⸫) and a solvent), films (films made of the resin composition (⸫)), laminates (laminated comprising a layer made of the resin composition (⸫) and one or more layers (X) different from the aforementioned layer), and packaging materials (packaging materials comprising the resin composition (⸫) or the aforementioned laminate).

[0060] [Coating liquid] The present invention also provides a coating solution comprising the resin composition of the present invention described above and a solvent. The resin composition of the present invention (for example, the pellets described above) can be placed in a solvent such as water, and the coating solution can be prepared by dissolving the resin composition in the solvent, for example, by stirring while heating in a constant temperature water bath. The heating temperature (set temperature of the constant temperature water bath) is preferably 60 to 100 °C, more preferably 75 to 95 °C. Water is preferred as the solvent, but an organic solvent may also be used in combination, for example. Examples of organic solvents include alcohols such as ethanol and isopropyl alcohol. The addition of alcohols makes it easier for water to evaporate from the coating solution, which is expected to improve productivity when producing a film from the coating solution.

[0061] The stirring method is not particularly limited, but examples include placing a stirring bar in the coating liquid and stirring it with a magnetic stirrer, or rotating a motor equipped with stirring blades.

[0062] The optimal viscosity range for the coating solution varies depending on the coating method, and the viscosity of the coating solution may be adjusted as appropriate according to the coating method. For example, when using the gravure coating method adopted in the examples, the viscosity of the coating solution measured by the measurement method described in the examples is preferably 5,000 mPa-s or less, more preferably 4,500 mPa-s or less, and even more preferably 3,100 mPa■s or less. A viscosity within this range makes it easier to obtain a uniform film during coating. [0063I The solid content concentration of the coating solution is adjusted as appropriate, taking into consideration various factors such as the type of coating method and the thickness of the coating film, so that the viscosity of the coating solution falls within the viscosity range mentioned above.

[0064] [film] The present invention also provides a film made of the resin composition of the present invention described above. The film is a film made up of layers of the resin composition of the present invention. The film may be a film made up of one layer of the resin composition of the present invention, or a film made up of two or more layers of the resin composition of the present invention. If the film is made up of two or more layers of the resin composition of the present invention, the composition of each layer may be the same or different from each other.

[0065] The method for manufacturing the film of the present invention is not particularly limited, but for example, a coating liquid containing the resin composition manufactured as described above may be applied to a substrate with low adhesion to the resin composition to create a coating (laminated) in which the resin composition covers the substrate, and then the substrate may be peeled off from the resin composition layer to isolate the resin composition layer. In this case, no adhesive is applied to the substrate in order to peel off the resin composition layer. Examples of substrates with low adhesion include PET film, BOPP film, PE film, and polylactic acid film. In this specification, a film manufactured by applying a coating liquid containing the resin composition of the present invention to a substrate, drying as necessary, and peeling off the substrate as necessary is also referred to as a coated film. Alternatively, as described above, a film made of the resin composition may be manufactured by extruding a molten resin composition from a film molding die to form a film.

[0066] As described above, the film of the present invention is a film made of the resin composition of the present invention, and since the resin composition contains modified starch and polyvinyl alcohol, the inventors have confirmed that the resulting film has excellent gas barrier properties. From the viewpoint of gas barrier properties, the oxygen permeability of the film of the present invention is preferably 5.0 cc, 20 m / m², 2 days, atm or less, and more preferably 4.0 cc, 20 m / m², at conditions of 20 °C and 65 RH. 2 . day . atm or less, more preferably 3.0 cc . 2 0 / >(, m / m 2The temperature is below , day. atm. Oxygen permeability can be measured using an oxygen permeability measuring device under the above-specified temperature and humidity conditions. The measurement may be performed under the conditions described in the examples.

[0067] [Method for manufacturing laminates] The present invention also provides a laminate comprising a layer made of the resin composition of the present invention and one or more layers (X) different from the said layer. The one or more layers (X) different from the layer made of the resin composition of the present invention may be any layer depending on the application in which the laminate of the present invention will be used, and may be, for example, a layer selected from the group consisting of a base layer, an adhesive layer, a resin layer, a metal layer, a metal vapor deposition layer, an inorganic vapor deposition layer, a paper layer, and a sealant layer. Note that the resin layer as layer (X) is a resin layer that is not made of the resin composition of the present invention.

[0068] The laminate includes, for example, a laminate which is a coating obtained by coating a substrate such as paper or film with the resin composition of the present invention. The method for manufacturing the laminate of the present invention is not particularly limited, but examples include a method of coating a substrate such as paper or film with the coating solution prepared by dissolving the resin composition of the present invention in a solvent such as water.

[0069] The method of applying the coating solution is not particularly limited and may be a batch method or a continuous method. Examples include direct gravure, reverse gravure, spray coating, curtain coating, flexo coating, and methods using a brush or pen.

[0070] The method for drying the coating film formed by applying the coating liquid is not particularly limited, but it is preferable to dry it by heating using a drying oven or heater. The drying temperature is preferably 50 to 150 °C, more preferably 60 to 150 °C, and even more preferably 70 to 140 °C. The drying time is preferably 1 to 200 seconds, more preferably 2 to 180 seconds, and even more preferably 5 to 160 seconds. Drying is preferably carried out in an atmospheric atmosphere at normal pressure. [0071I When manufacturing a laminate of the present invention by coating paper with the resin composition of the present invention, or a coating liquid containing the resin composition of the present invention, the adhesive strength of the resin composition to paper is relatively high, so it may be coated directly onto the paper. On the other hand, when manufacturing a laminate of the present invention by coating a resin film with the resin composition of the present invention, the adhesive strength is generally weaker compared to coating paper, so it is preferable to coat the film with an adhesive beforehand. A general-purpose laminating adhesive can be used as the adhesive to be applied. For example, (solvent-free), aqueous, or heat-melt adhesives mainly composed of poly(ester)urethane, polyester, polyamide, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, casein, etc. can be used. Among these, polyolefin-based or urethane-based adhesives are preferred, considering heat resistance and flexibility to accommodate dimensional changes of each substrate. The adhesive layer can be applied by methods such as direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, Fontaine coating, and other methods, and the coating amount after drying is preferably 1 to 8 g / m², more preferably 2 to 7 g / m², and even more preferably 3 to 6 g / m², in order to achieve sufficient adhesion. If the coating amount is less than 1 g / m², it becomes difficult to bond the entire surface, and the adhesive strength decreases. If it exceeds 8 g / m², it takes a long time for the film to fully harden, unreacted material tends to remain, and the adhesive strength decreases. In a preferred embodiment of the present invention, the laminate of the present invention may include, as layer (X), a base layer (X1) and a further layer (X2), more preferably, the further layer (X2) may be an adhesive layer. [0072I The thickness of the layer made of the resin composition of the present invention in the laminate of the present invention is preferably 1 to 300 vm, more preferably 1 to 100 vm, and even more preferably 1 to 50 AC m. When the thickness of the layer made of the resin composition in the laminate is within the above range, good film-forming properties and oxygen barrier properties are easily obtained. When the laminate contains two or more layers made of the resin composition, it is preferable that the thickness of each layer is within the above range. [0073I The thickness of the laminate of the present invention may be set appropriately depending on the application of the laminate of the present invention, but from the viewpoint of suitability for processing into food packaging material, it is preferably 1 to 800 mm, more preferably 1 to 600 mm, and even more preferably 5 to 200 mm.

[0074] Examples of the layer configurations of the laminate of the present invention include: a layer configuration of paper / a layer made of the resin composition of the present invention; a layer configuration of film / a layer made of the resin composition of the present invention; a layer configuration of paper / a layer made of the resin composition of the present invention / adhesive / paper; a layer configuration of paper / a layer made of the resin composition of the present invention / adhesive / film; a layer configuration of film / a layer made of the resin composition of the present invention / adhesive / paper; and a layer configuration of film / a layer made of the resin composition of the present invention / adhesive / film. From the viewpoint of adhesion, it is preferable that the paper and the layer made of the resin composition of the present invention are directly adjacent to each other. Also from the viewpoint of adhesion, it is preferable that the film and the layer made of the resin composition of the present invention have an adhesive between them. In a preferred embodiment, the laminate has a layer configuration in the order of paper / a layer made of the resin composition of the present invention / adhesive / film. The type of film or paper is not particularly limited, but the film is preferably a polyethylene film. In addition, there may be other layers adjacent to the film or paper.

[0075] [Packaging material] The present invention also provides a packaging material comprising the resin composition of the present invention or the laminate of the present invention. The packaging material has high oxygen barrier properties and excellent biodegradability, and when the packaging material is a laminate, it has excellent adhesion between the layer made of the resin composition and the substrate (preferably paper or resin film), making it suitable for use as a food packaging material. Examples

[0076] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. [0077I <Evaluation Method> (1) Viscosity of the coating solution The solution viscosity of coating solutions (solid content concentration 10%) prepared using the resin compositions obtained in the examples and comparative examples was evaluated according to the following method. The coating solutions prepared using the resin compositions obtained in the examples and comparative examples were left to stand in a room at 23°C for at least one day. Next, the spindle of the following Type B viscometer (analog viscometer T, manufactured by Eiko Seiki Co., Ltd.) was inserted into the coating solution, and the torque was measured when it was rotated at 60 rpm. The torque value was converted to viscosity using a conversion table specified by the manufacturer. The conversion table allows the viscosity to be obtained by multiplying the measured torque by a coefficient determined by the jig and rotation speed used. In this example, the viscosity was obtained by multiplying the torque value by 100 based on the conversion table. When the solution viscosity of the coating solution without carboxylic acid compound (C) is A (m Pa • s) and the melt viscosity of the coating solution with carboxylic acid compound (C) is B (m Pa • s), the viscosity reduction rate was calculated using the following formula. Viscosity reduction rate (%) = [(A — B) / A] X 1 0 0

[0078] (2) Observation of the film's appearance (suitability for coating) The films obtained in the examples and comparative examples were observed visually or using an optical microscope (magnification: 20x) to assess the surface condition of the films, and their suitability for gravure coating was evaluated using the following criteria: ○, △, and X. ○: No streaks were observed under an optical microscope (magnification: 2Xx). △: Faint streaks were observed under an optical microscope (magnification: 20x), but no streaks were observed with the naked eye. X: A streaky pattern was observed visually.

[0079] (3) Viscosity of water-soluble polymer (B) In accordance with JIS Z 8 8 0 3 (Falling Ball Viscometer) and J | SK 6 7 2 6 (Test Method for Polyvinyl Alcohol), 4% aqueous solutions of polyvinyl alcohol used in the examples and comparative examples were prepared, and the viscosity at 20°C was measured using a Hebler viscometer, and this was defined as the viscosity (20°C) of the 4% aqueous solution of water-soluble polymer (B). [0080I Materials used> Modified starch (A) • (A-1): ECOFILM (registered trademark); corn starch modified with propylene oxide, amylose content 70% by mass, manufactured by 1 ngredion.

[0081] Water-soluble polymer (B) • (B-1): ELVAN 0 L (registered trademark) 71-30; polyvinyl alcohol resin, degree of saponification 99 m₀ 1% or higher, viscosity 27-33 mPa•s (20°C, 4% aqueous solution), manufactured by Kuraray Co., Ltd. • (B-2); Kuraray Poval (registered trademark) 4-98; Polyvinyl alcohol resin, degree of saponification 98 m₀ 1% or higher, viscosity 4 mPa-s (20 °C, 4% aqueous solution), manufactured by Kuraray Co., Ltd.

[0082] Carboxylic acid compounds (C) • (〇 1 - 1 ); Acetic acid; Manufactured by Fujifilm Wako Pure Chemical Industries. • (C3-1); Magnesium acetate; Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. • (C 3 - 2); Calcium acetate; manufactured by FUJIFILM Wako Pure Chemical Corporation • (C 3 - 3); Zinc acetate; manufactured by FUJIFILM Wako Pure Chemical Corporation • (C 3 - 4); Calcium propionate; manufactured by FUJIFILM Wako Pure Chemical Corporation • (C 3 - 5); Calcium sorbate; manufactured by FUJIFILM Wako Pure Chemical Corporation • (C 2 - 1); Adipic acid; manufactured by FUJIFILM Wako Pure Chemical Corporation • (C 2 - 2); Citric acid; manufactured by FUJIFILM Wako Pure Chemical Corporation • (C 4); Sodium stearate; manufactured by FUJIFILM Wako Pure Chemical Corporation

[0083] <Example 1> (Resin composition) As raw materials, ECOFILM (registered trademark) (8.70 kg), ELVANOL (registered trademark) 71 - 30 (1.21 kg), and acetic acid (90 g) were mixed in a tumbler mixer for 2 hours, and the resulting mixture was fed into a twin - screw extruder connected to a liquid pump. The schematic diagram of the twin - screw extruder used in Example 1 is shown in Figure 1, and the screw diameter, L / D ratio, rotation speed, operation mode, and temperature profile (Table 1) of the extruder are shown below.

[0084] [Table 1] Temperature profile ADC C1 C2 C3 C4 C5 C6 C7 C8 C9 CIO C11 Adapter die 4〇7〇8〇9〇120140130120120100100l〇〇100

[0085] Screw diameter: 27 mm L / D ratio: 48 Screw rotation speed 500 rpm Operating method: Co-rotation (self-wiping by interlocking) method

[0086] Specifically, the resulting mixture was fed into the barrel at a rate of 3.5 kg / hour through the gravitational feeder of the twin-screw extruder 8 shown in Figure 1, passing through the hopper 9 at C1. Water was injected into the barrel at a flow rate of 26 g / min through a liquid pump (L) at C4. The temperature range of C5–C9 is the cooking range, and complete gelatinization was completed within this range. The strand die is located from C11 onwards. The resin composition was extruded through a multi-hole strand nozzle and cut with a rotary cutter to form the strands into pellets. Since the pellets contained excess moisture, the moisture was removed with hot air while applying constant vibration to prevent sticking.

[0087] (Coating liquid) The resulting resin composition pellets and deionized water were mixed in a ratio that resulted in a solid content concentration of 10%, and the mixture was heated and stirred at 80°C for 4 hours to obtain a homogeneous solution (coating solution).

[0088] The viscosity of the obtained coating solution was measured using a Type B viscometer under conditions of a rotor rotation speed of 60 rpm and a temperature of 23 °C.

[0089] (Film, Laminate) A coating solution was gravure coated onto a PET film at a speed of 6 m / min (gravure roll: 36 lines, cell volume 150 cc / m², peripheral speed ratio: 100%). After coating, drying was performed at 80 °C to obtain a laminate having a resin composition layer and a PET film substrate layer. Subsequently, the resin composition layer was peeled off the PET film to obtain a film with a thickness of 15 Atm. [0090I The appearance of the obtained film was observed visually and with an optical microscope to evaluate its coating suitability.

[0091] Example 2 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that magnesium acetate (90 g) was used as the carboxylic acid compound (C).

[0092] Example 3 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that calcium acetate (90 g) was used as the carboxylic acid compound (C).

[0093] Example 4 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that zinc acetate (90 g) was used as the carboxylic acid compound (C).

[0094] Example 5 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that calcium propionate (90 g) was used as the carboxylic acid compound (C).

[0095] Example 6 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that calcium propionate (180 g) was used as the carboxylic acid compound (C).

[0096] Example 7 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that calcium propionate (450 g) was used as the carboxylic acid compound (C). [0097I Example 8 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that calcium sorbate (90 g) was used as the carboxylic acid compound (C).

[0098] Example 9 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that calcium sorbate (180 g) was used as the carboxylic acid compound (C).

[0099] Example 1 〇 > A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that calcium sorbate (450 g) was used as the carboxylic acid compound (C).

[0100] <Example 1 1> A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that adipic acid (90 g) was used as the carboxylic acid compound (C).

[0101] <Examples 1 & 2> A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that citric acid (90 g) was used as the carboxylic acid compound (C).

[0102] <Example 1 3> Resin compositions, coating solutions, laminates, and films were obtained in the same manner as in Example 1, except that ELVANOL (registered trademark) 71-30 (2.85 kg) was used as the water-soluble polymer (B) and calcium propionate (90 g) was used as the carboxylic acid compound (C).

[0103] <Example 1 4> A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that Kurarepoval (registered trademark) 4-98 (1.64 kg) was used as the water-soluble polymer (B) and calcium propionate (90 g) was used as the carboxylic acid compound (C). [0104I Example 1 5 > (Laminated structure) A laminate was obtained in the same manner as in Example 1, except that kraft paper (50 g / m²) was used as the coating substrate instead of PET film, and the resin composition layer was not peeled off.

[0105] Example 1 6 > (Laminated structure) In Example 1, a laminate was obtained by dry laminating a 20 jucum thick LDPE film onto the resin composition layer side of the laminate obtained in Example 5 using a polyurethane adhesive.

[0106] <Example 1 7> (packaging material) Two 10 cm square pieces were cut from the laminate obtained in Example 16, the LDPE film sides of the two pieces were placed together, and the three sides were sealed with a heat sealer at 180 °C to obtain a bag-shaped packaging material.

[0107] <Comparative Example 1> A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that ECOFILM (registered trademark) (8.70 kg) and ELVAN 0 L (registered trademark) 71-30 (1.21 kg) were used as raw materials, and no carboxylic acid compound (C) was added.

[0108] <Comparative Example 2> A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that ECOFILM (registered trademark) (8.70 kg) and ELVAN 0 L (registered trademark) 71-30 (2.85 kg) were used as raw materials, and no carboxylic acid compound (C) was added. [0109I <Comparative Example 3> A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that ECOFILM (registered trademark) (8.70 kg) and Kurarepoval (registered trademark) 4-98 (1.64 kg) were used as raw materials, and no carboxylic acid compound (C) was added.

[0110] Comparative Example 4 > The raw materials used are ECOFILM (registered trademark) (8.70 kg) and ELVAN 0 L (registered trademark) 71-30 (1.21 kg). s A resin composition, coating solution, laminate, and film were obtained in the same manner as in Example 1, except that sodium stearate (90 g) was used. [01 1 1] The evaluation results for Examples 1 to 14 and Comparative Examples 1 to 4 are shown in Table 2.

[0112] Evaluation of resin composition coating liquids Modified starch (A) Water-soluble polymer (O) Carboxylic acid compound (C) Coating Content [mass content [mass viscosity viscosity reduction rate] Type Quantity Part Type Type Carbon Number Content [Quality [mPa* s] [Parts] [Parts] [%] Suitability 1 A - 1 100 B - 1 14 C 1 - 1 2 1 3500 51. 6 △ A — 1 100 1 14 G 3 — 1 2 1 4200 2 4L 9 △ 100 B - 1 14 C 3 - 2 2 1 2000 72. 3 3 A - 1 〇 14 C 3 - 3 2 4 A - 1 100 B - 1 1 508 93. 0 〇 5 A "™ 1 100 B - 1 14 1 970 86, 6 〇 14 3 2 656 6 A — 1 100 B - 1 C 3 — 4 90, 9 〇 Actual B - 1 14 5 444 93. 9 7 A- 1 100 ○ 100 14 1 2420 66. 5 8 A- 1 1 〇 Example 9 A - 1 100 B — 1 14 C 3 — 5 6 2 1344 81. 4 〇 A- 1 100 B - 1 14 5 932 87. 1 1 〇 〇 △ 14 C 2 - 1 6 1 1 1 A — 1 100 B - 1 3740 48, 3 6 14 C 2 - 2 1 3020 58. 2 1 2 A — 1 100 B — I 〇 100 B - 1 33 2080 59. 2 1 3 A - 1 〇 C 3 - 4 3 1 A — 1 1 4 100 B - 2 19 2050 67. 7 〇 One - One — X 100 B - 1 14 7230 1 A - 1 Hiichi - - — X 100 B - 1 33 5100 2 A - 1 Comparison B ™» 2 - X 100 19 6340 3 J\, XExample B — 1 X 4 A — 1 100 14 C 4 18 1 >10000 The films obtained in the two examples and comparative example of SS NVQ03 were stored at 20 °C and 65% RH for two weeks to allow them to adjust the humidity. After that, they were attached to an oxygen permeability measuring device and the oxygen permeability was measured. The measurement conditions were as follows. Equipment: Modern Control Co., Ltd. "MOCONOX - TRAN 2 / 20 J" Temperature: 2 ○ 0 C Humidity on the oxygen supply side and carrier gas side: 65% RH Oxygen pressure: 1.0 atm Carrier gas pressure: 1.0 atm The film obtained in Example 5 was measured and found to have a viscosity of 1.0 cc.20 juc m / m². 2. day . atm, and the measurement results for the film obtained in Comparative Example 2 were 1.8 cc .2 0 (, m / m 2 The temperature was . day . atm. It is also expected that other examples using similar modified starch and water-soluble polymers, other than Example 5, will exhibit similar oxygen barrier properties.

[0114] As shown in Table 2, the 10% solid content aqueous solution (coating solution) of the resin composition of the present invention obtained in Examples 1 to 14 showed a decrease in solution viscosity of 41.9 to 93.9% compared to the 10% solid content aqueous solution (coating solution) of the resin composition that did not contain the carboxylic acid compound (C) in Comparative Examples 1 to 3, confirming an improvement in coating suitability in gravure coating. On the other hand, as in Comparative Example 4, the 10% solid content aqueous solution (coating solution) of the resin composition containing a metal salt of a long-chain carboxylic acid with 18 carbon atoms showed an increase in solution viscosity due to the inclusion of the carboxylic acid, indicating that the coating suitability was not improved at all. In Table 2, the viscosities of Examples 1 to 14 and Comparative Example 4 are the melt viscosity B (mPa•s) of the coating solution to which the carboxylic acid compound (C) was added. Also in Table 2, the viscosities of Comparative Examples 1 to 3 are the solution viscosity A (mPa■s) of the coating solution without the addition of the carboxylic acid compound (C). Explanation of the symbols

[0115] 8. Twin-screw extruder 9 Hopper ○ Liquid injection nozzle 1 Resin thermometer 2 Resin pressure gauge 3 Adapter 4 Die

Claims

1. Scope of Claims

1. A resin composition comprising 10 to 40 parts by mass of a water-soluble polymer (B) per 100 parts by mass of modified starch (A), and 0.0 5 to 10 parts by mass of at least one carboxylic acid compound (C) selected from the group consisting of acetic acid (C1), carboxylic acids having 4 to 10 carbon atoms (C2), and metal salts of carboxylic acids having 2 to 10 carbon atoms (C3).

2. The resin composition according to Claim 1, wherein the average amylose content of the modified starch (A) is 50% by mass or more.

3. The resin composition according to claim 1, wherein the modified starch (A) is at least one selected from the group consisting of etherified starch, esterified starch, cationized starch, and crosslinked starch.

4. The resin composition according to claim 1, wherein the water-soluble polymer (B) is a polyvinyl alcohol-based resin.

5. The resin composition according to claim 1, wherein the carboxylic acid compound (C) comprises 0.05 to 10 parts by mass of acetic acid (C1) and / or a carboxylic acid (C2) having 4 to 10 carbon atoms, per 100 parts by mass of modified starch (A).

6. The resin composition according to claim 1, wherein the carboxylic acid compound (C) comprises 0.05 to 10 parts by mass of a metal salt (C3) of a carboxylic acid having 2 to 1 carbon atoms, per 100 parts by mass of modified starch (A).

7. A coating liquid comprising the resin composition according to any one of claims 1 to 6 and a solvent.

8. A film comprising the resin composition according to any one of claims 1 to 6.

9. A laminate comprising a layer made of the resin composition according to any one of claims 1 to 6, and one or more layers (X) different from the said layer.

10. The laminate according to claim 9, wherein one or more layers (X) are layers selected from the group consisting of a substrate layer, an adhesive layer, a resin layer, a metal layer, a metal vapor deposition layer, an inorganic vapor deposition layer, a paper layer, and a sealant layer.

11. The laminate according to claim 9, wherein layer (X) comprises at least a substrate layer, the substrate layer being a layer of paper or film.

12. The laminate according to claim 9, wherein the layer (X) comprises at least a substrate layer (X1) and a further layer (X2).

13. A packaging material comprising the film according to claim 8, or the laminate according to claim 9.

Images