Resin composition

Abstract

A resin composition is provided with which it is possible to form coated objects having reduced adhesion to metal rolls during production and having excellent oxygen-barrier properties and from which films or sheets excellent in terms of oxygen-barrier property, low-humidity impact strength, and color tone can be formed. This resin composition comprises 50-98 parts by mass of a modified starch (A), 2-50 parts by mass of poly(vinyl alcohol) (B), 0.1-10 parts by mass of a polyoxyalkylene (C), and 0-5 parts by mass of a polyol plasticizer (D) as an optional component, the total content of the (A), (B), (C), and (D) being 100 parts by mass.

Description

Technical Field

[0001] The present invention relates to a resin composition used for food packaging containers and the like, a water-containing composition containing the resin composition, a coated product obtained by coating the water-containing composition on paper or a film and a method for producing the same, a multilayer structure containing the coated product, a film or sheet made of the resin composition, a laminate containing the film or sheet, a packaging material made of the coated product or the multilayer structure, and a packaging tray or cup made of the film or sheet or the laminate and a method for producing the same.

Background Art

[0002] Conventionally, a resin composition containing modified starch and polyvinyl alcohol has been widely used for containers for packaging food because of its excellent biodegradability (for example, Japanese Patent No. 4782284).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Among these containers for packaging food, there are many containers using, as a material, a coated product obtained by coating a water-containing composition containing the resin composition and water on paper or a film, a laminate of a film or sheet made of the resin composition and a moisture-proof resin, and a thermoformed container thereof, and high oxygen barrier properties are required for the coated product and the thermoformed container. On the one hand, the coating is produced by coating a paper or film conveyed by a take-up machine, for example, with a water-containing composition discharged from the die outlet of an extruder. However, according to the study by the present inventor, a water-containing composition capable of ensuring high oxygen barrier properties has high adhesion to metal, and thus may stick to a metal roll during conveyance by a take-up machine, resulting in damage to the coating or the like. It has also been found that the bend resistance when the coating is bent is not sufficient. In addition, in the case of a film or sheet, the color tone and impact strength under low humidity are not sufficient, which may impair the appearance of food. Moreover, there is a problem that the container breaks when it is impacted during low-humidity storage including a refrigerated environment.

[0005] Therefore, an object of the present invention is to overcome the conventional problems in the production of both molded articles of a coating, a film or a sheet. In the case of the coating, a resin composition capable of forming a coating having low adhesion to a metal roll during production and excellent oxygen barrier properties and bend resistance, a water-containing composition containing the resin composition, a coating obtained by coating the water-containing composition on paper or film, a production method thereof, a multilayer structure including the coating, and a packaging material made of the coating or the multilayer structure are provided. In addition, in the case of a film or a sheet, a resin composition capable of forming a film or a sheet excellent in oxygen barrier properties, impact strength under low humidity and color tone, a film or a sheet made of the resin composition, a laminate including the film or the sheet, and a packaging tray or cup made of the film or the sheet or the laminate and a production method thereof are provided. In the present specification, the oxygen barrier property means the oxygen barrier property of the coating, as well as the film or the sheet, unless otherwise specified.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that the resin composition containing 50 to 98 parts by mass of modified starch (A), 2 to 50 parts by mass of polyvinyl alcohol (B), 0.1 to 10 parts by mass of polyoxyalkylene (C) and optionally 0 to 5 parts by mass of polyol plasticizer (D) can solve the above problems, and completed the present invention.

[0007] [1] 50 to 98 parts by mass of modified starch (A), 2 to 50 parts by mass of polyvinyl alcohol (B), 0.1 to 10 parts by mass of polyoxyalkylene (C) and optionally 0 to 5 parts by mass of polyol plasticizer (D) A resin composition, comprising the same, and the total content of (A), (B), (C) and (D) being 100 parts by mass. [2] The resin composition according to [1], wherein the total content of (A), (B), (C) and (D) is 80% by mass or more based on the mass of the resin composition. [3] The resin composition according to [1] or [2], wherein the average amylose content of the modified starch (A) is 50% by mass or more. [4] The resin composition according to any one of [1] to [3], wherein the modified starch (A) is at least one selected from the group consisting of etherified starch, esterified starch, cationized starch and crosslinked starch. [5] The resin composition according to any one of [1] to [4], wherein the modified starch (A) is at least one selected from the group consisting of etherified starch having a hydroxyalkyl group having 2 to 6 carbon atoms and esterified starch having a structural unit derived from a dicarboxylic acid anhydride. [6] The resin composition according to any one of [1] to [5], wherein the polyvinyl alcohol (B) has a viscosity of 1 to 50 mPa·s at 20°C in a 4% aqueous solution measured in accordance with JIS Z 8803. [7] A water-containing composition containing the resin composition according to any one of [1] to [6], wherein the water content is 1 to 50% by mass. [8] A coated article obtained by coating the water-containing composition according to [7] on paper or a film. A multilayer structure comprising the coating described in [9][8] and one or more layers (X). A packaging material comprising the coating described in

[10] [8] or the multilayer structure described in [9]. A step of coating the aqueous composition described in [7] onto a film or paper conveyed by a take-up machine using an extruder (1), wherein in this step, the formula (1); Draw ratio = (take-up speed of the take-up machine) / (flow rate at the die outlet of the extruder) (1) A method for producing the coating according to [8], wherein the draw ratio represented by is 5 to 20. A film or sheet made of the resin composition described in any one of

[12] [1] to [6]. A laminate comprising the film or sheet described in

[13]

[12] and one or more layers (X). A packaging tray or cup made of the film or sheet described in

[14]

[12] or the laminate described in

[13] . A step of forming a film or sheet by molding the resin composition described in any one of [1] to [6] using an extruder (15); a step of laminating one or more layers (X) onto the obtained film or sheet by lamination to obtain a laminate; and a step of thermoforming the obtained laminate into a packaging tray or cup; A method for producing the packaging tray or cup according to

[14] , comprising. [Advantages of the Invention]

[0008] Since the resin composition of the present invention has low adhesion to a metal roll during production, it can effectively prevent sticking to the metal roll and can form a coating excellent in oxygen barrier properties and flex resistance. Further, the resin composition of the present invention can also form a film or sheet excellent in oxygen barrier properties, impact strength under low humidity, and color tone. Therefore, it can be suitably used as a material for food packaging and containers, etc. [Brief Description of the Drawings]

[0009]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0010] [Resin Composition] The resin composition of the present invention contains 50 to 98 parts by mass of modified starch (A), 2 to 50 parts by mass of polyvinyl alcohol (B), 0.1 to 10 parts by mass of polyoxyalkylene (C), and optionally 0 to 5 parts by mass of a polyol plasticizer (D), and the total content of components (A), (B), (C), and (D) is 100 parts by mass.

[0011] The present inventor has found that when the resin composition contains 0.1 to 10 parts by mass of polyoxyalkylene (C) in addition to 50 to 98 parts by mass of modified starch (A) and 2 to 50 parts by mass of polyvinyl alcohol (B), while maintaining excellent oxygen barrier properties, the adhesion to a metal roll can be significantly reduced during the production of a coating, and the flexural resistance can be improved. This is presumably because polyoxyalkylene (C) has a function of weakening the adhesive force between the hydroxyl groups of modified starch (A) and polyvinyl alcohol (B) and the metal, as well as a function of enhancing the strength. Furthermore, the present inventor has also found that with such a composition, the drawability during production is good and the maximum draw ratio can be improved. This is presumably because polyoxyalkylene (C) has a function of weakening the hydrogen bond between the hydroxyl groups of modified starch (A) and polyvinyl alcohol (B) and water in the aqueous composition. In this specification, the drawability refers to the property that when coating the aqueous composition discharged from the die outlet of the extruder onto the conveyed paper or film, the aqueous composition can be coated without tearing. When the drawability is improved or enhanced, it means that even when the paper or film is conveyed at a high speed, the aqueous composition can be coated without tearing and is easily coated. In addition, in the film or sheet made of the resin composition of the present invention, it has been found that while maintaining excellent oxygen barrier properties, the yellowness of the molded article is suppressed, and the impact strength under low humidity is improved. This is presumably because polyoxyalkylene (C) weakens the hydrogen bonds between the hydroxyl groups of modified starch (A) and polyvinyl alcohol (B) and the water in the hydrous composition, suppresses the decomposition reaction during production, and has the function of increasing the strength of the obtained film or sheet.

[0012] <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 crosslinked starch.

[0013] Examples of the starch include starch derived from cassava, corn, potato, sweet potato, sago, tapioca, sorghum, beans, bracken, rush, water chestnut, wheat, rice, oats, kudzu, and pea. Among them, starch derived from corn and cassava is preferable, and starch derived from high-amylose corn is more preferable. The starch can be used alone or in combination of two or more.

[0014] Examples of the etherified starch include alkyl etherified starch such as methyl etherified starch; carboxyalkyl etherified starch such as carboxymethyl etherified starch; hydroxyalkyl etherified starch such as etherified starch having a hydroxyalkyl group having 2 to 6 carbon atoms; and allyl etherified starch can also be used.

[0015] Examples of esterified starch include esterified starch having a structural unit derived from a carboxylic acid such as esterified starch having a structural unit derived from acetic acid; esterified starch having a structural unit derived from a dicarboxylic acid anhydride such as esterified starch having a structural unit derived from maleic anhydride, esterified starch having a structural unit derived from phthalic anhydride, and esterified starch having a structural unit derived from octenyl succinic anhydride; and esterified starch having a structural unit derived from an oxo acid such as nitrate esterified starch, phosphate esterified starch, and urea phosphate esterified starch. Other examples include xanthic acid esterified starch and acetoacetic acid esterified starch.

[0016] Examples of cationized starch include the reaction product of starch and 2-diethylaminoethyl chloride, and the reaction product of starch and 2,3-epoxypropyltrimethylammonium chloride.

[0017] Examples of crosslinked starch include formaldehyde crosslinked starch, epichlorohydrin crosslinked starch, phosphate crosslinked starch, and acrolein crosslinked starch.

[0018] As the modified starch (A), from the viewpoint of film-forming properties during the production of films or sheets and coatings, it is preferably at least one selected from the group consisting of etherified starches having a hydroxyalkyl group with 2 to 6 carbon atoms and esterified starches having a structural unit derived from a dicarboxylic anhydride. 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 a structural unit derived from maleic anhydride, esterified starch having a structural unit derived from phthalic anhydride, and esterified starch having a structural unit derived from octenyl succinic anhydride. The modified starch (A) can be used alone or in combination of two or more. In this specification, the number of carbon atoms described before "starch" represents the number of carbon atoms of the group substituted for one hydroxyl group in the starch (the group formed by modifying one hydroxyl group in the starch). For example, an etherified starch having a hydroxyalkyl group with 2 to 5 carbon atoms indicates that the number of carbon atoms of the hydroxyalkyl group formed by modifying one hydroxyl group in the starch is 2 to 5.

[0019] The etherified starch having a hydroxyalkyl group with 2 to 6 carbon atoms may be obtained, for example, by the reaction of an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide with starch. The average number of hydroxy groups used for modification is preferably 0.05 to 2 per glucose unit in the starch.

[0020] The modified starch (A) preferably has an average amylose content in the modified starch (A) of 50% by mass or more, more preferably 55% by mass or more, still 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 at or above the above lower limit, it is easy to enhance the oxygen barrier property, biodegradability, and molding processability. The amylose content in the modified starch (A) is usually 90% by mass or less. In this specification, the amylose content can be measured by the iodine colorimetric method described in, for example, "Starch 50 No.4 158-163 (1998)". Note that the average amylose content indicates the amylose content of the single type of modified starch when there is one type of modified starch, and when two or more types of modified starch are used, it is the weighted average of the amylose contents of two or more types of modified starch. Therefore, for example, when two or more types of modified starch are used and the average amylose content is 50% by mass or more, it may contain a modified starch with an amylose content of less than 50% by mass.

[0021] The modified starch (A) preferably has a moisture content in the modified starch (A) of 5 to 15% by mass.

[0022] Commercially available modified starch (A) can also be used. Examples of representative commercial products of modified starch (A) include, for example, ECOFILM (trademark) and National1658 (trademark), which are hydroxypropyl etherified starches manufactured by Ingredion.

[0023] The content of the modified starch (A) is 50 to 98 parts by mass with respect to a total of 100 parts by mass of the components (A), (B), (C), and (D). When the content of the modified starch (A) is less than 50 parts by mass or exceeds 98 parts by mass, the adhesion to the metal roll during production tends to increase, and the oxygen barrier property, drawability, maximum draw ratio, flexural resistance, impact strength under low humidity, and color tone tend to decrease. The content of the modified starch (A) is 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 80 parts by mass or more, and 98 parts by mass or less, preferably 95 parts by mass or less, more preferably 90 parts by mass or less. When the content of the modified starch (A) is within the above range, it is likely to reduce the adhesion to the metal roll during production, and it is also easy to enhance the oxygen barrier property, drawability, maximum draw ratio, flex resistance, impact strength under low humidity, and color tone. In this specification, excellent color tone means low coloring degree, for example, low b value (yellowness, YI), and an increase or improvement in color tone means a reduction in coloring degree, for example, a reduction in b value.

[0024] <Polyvinyl alcohol (B)> The polyvinyl alcohol (B) contained in the resin composition of the present invention preferably has a saponification degree of 80 to 99.8 mol%. When the saponification degree of the polyvinyl alcohol (B) is within the above range, it is easy to enhance the drawability, maximum draw ratio, and oxygen barrier property. The saponification degree is more preferably 85 mol% or more, still more preferably 88 mol% or more. In this specification, the saponification degree refers to the molar fraction of the hydroxyl group with respect to the total of the hydroxyl group and the ester group in the polyvinyl alcohol (B).

[0025] Polyvinyl alcohol (B) can further contain other monomer units in addition to vinyl alcohol units. Examples of other monomer units include monomer units derived from ethylenically unsaturated monomers. Examples of ethylenically unsaturated monomers include α-olefins such as ethylene, propylene, n-butene, isobutylene, and 1-hexene; acrylic acid and its salts; unsaturated monomers having an acrylate group; methacrylic acid and its salts; unsaturated monomers having a methacrylate 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); vinyl ethers such as 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, dodecyl vinyl ether, stearyl vinyl ether, and 2,3-diacetoxy-1-vinyloxypropane; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides 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; vinyl silyl compounds such as vinyltrimethoxysilane, isopropenyl acetate; vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl carlylate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl oleate, and vinyl benzoate. Also, monomer units derived from unsaturated monomers that have not been saponified are included in the other monomer units.The content of other monomer units is preferably 10 mol% or less, more preferably 5 mol% or less.

[0026] The production method of polyvinyl alcohol (B) is not particularly limited. For example, a method of polymerizing a vinyl alcohol monomer and optionally other monomers, and saponifying the obtained polymer to convert it into vinyl alcohol units can be mentioned. Examples of the polymerization method during polymerization include batch polymerization, semi-batch polymerization, continuous polymerization, semi-continuous polymerization, etc. Examples of the polymerization method include known methods such as bulk polymerization method, solution polymerization method, suspension polymerization method, emulsion polymerization method, etc. For the saponification of the polymer, known methods can be applied. For example, it can be carried out in a state where the polymer is dissolved in alcohol or hydrous alcohol. The alcohol that can be used at this time is preferably a lower alcohol such as methanol, ethanol, etc.

[0027] The viscosity of polyvinyl alcohol (B) at 20 °C in a 4% aqueous solution measured in accordance with JIS Z 8803 is preferably 1 mPa·s or more, more preferably 2 mPa·s or more, still more preferably 3 mPa·s or more, and preferably 45 mPa·s or less, more preferably 35 mPa·s or less. When the viscosity of polyvinyl alcohol (B) is above the above lower limit, the oxygen barrier property is likely to be improved, and when the viscosity is below the above upper limit, the drawability and the maximum draw ratio are likely to be increased. The viscosity of polyvinyl alcohol (B) can be measured using a viscometer, for example, by the method described in the examples.

[0028] The content of polyvinyl alcohol (B) is 2 to 50 parts by mass with respect to a total of 100 parts by mass of components (A), (B), (C) and (D). When the content of polyvinyl alcohol (B) is less than 2 parts by mass and more than 50 parts by mass, the adhesion to the metal roll during production tends to increase, and the oxygen barrier property, drawability, maximum draw ratio, flexural resistance and impact strength under low humidity tend to decrease. The content of polyvinyl alcohol (B) is 2 parts by mass or more, preferably 5 parts by mass or more, 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. When the content of polyvinyl alcohol (B) is at least the above lower limit, it is easy to enhance the oxygen barrier property, drawability, maximum draw ratio, flexural fatigue resistance, and impact strength under low humidity. When the content is at most the above upper limit, it is easy to reduce the adhesion to the metal roll during production.

[0029] <Polyoxyalkylene (C)> Polyoxyalkylene (C) represents polyalkylene oxide and polyalkylene glycol, and has a structural unit (also referred to as structural unit (2)) represented by the following formula (2). Polyoxyalkylene (C) may have two or more different structural units (2). [Chemical formula] [In the formula, R is an alkylene group, and n is 1 or more]

[0030] In formula (2), examples of the alkylene group include alkylene groups having 2 to 10 carbon atoms such as ethylene group, propylene group, trimethylene group, butylene group, isobutylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, and decylene group. Among these, from the viewpoints of being likely to reduce the adhesion to the metal roll during production and being likely to enhance the drawability, maximum draw ratio, flexural fatigue resistance, and impact strength under low humidity, an alkylene group having 2 to 6 carbon atoms is preferable, and an ethylene group and / or a propylene group is more preferable. When n is 2 or more, these alkylene groups can be used alone or in combination of two or more.

[0031] In formula (2), n is preferably 5 or more, more preferably 50 or more, still more preferably 100 or more, and preferably 120,000 or less, more preferably 70,000 or less. When n is within the above range, it is easy to enhance oxygen barrier properties, drawability, maximum draw ratio, flexural fatigue resistance, and impact strength under low humidity, and it is easy to reduce the adhesion to a metal roll during production. When the polyoxyalkylene (C) contains different structural units (2), the repeating number n of each structural unit may be the same or different.

[0032] Examples of the polyalkylene oxide include polymers having structural units derived from alkylene oxides having 2 to 6 carbon atoms, specifically polyethylene oxide, polypropylene oxide, polytrimethylene oxide (polyoxetane), polybutylene oxide, polyisobutylene oxide, or copolymers of monomers constituting these. Examples of the polyalkylene glycol include polymers having structural units derived from alkylene glycols having 2 to 6 carbon atoms, specifically polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polybutylene glycol, polyisobutylene glycol, or copolymers of monomers constituting these. Among these, from the viewpoint of easily reducing the adhesion to a metal roll during production and easily enhancing drawability, maximum draw ratio, flexural fatigue resistance, and impact strength under low humidity, the polyoxyalkylene (C) is preferably polyethylene oxide, polypropylene oxide, polyethylene glycol, polypropylene glycol, or a copolymer of monomers constituting these. Preferred examples of the copolymer include copolymers of ethylene oxide and propylene oxide, copolymers of ethylene glycol and propylene glycol, and the like.

[0033] Polyoxyalkylene (C) may contain structural units derived from monomers other than the structural unit (2) as long as the effects of the present invention are not impaired. When polyoxyalkylene (C) is a copolymer, the polymerization form of the copolymer is not particularly limited, and it may be any of random, block, graft, or tapered forms.

[0034] The weight average molecular weight of polyoxyalkylene (C) is preferably 10,000 or more, more preferably 50,000 or more, preferably 5,000,000 or less, and more preferably 3,000,000 or less. When the weight average molecular weight is within the above range, it is easy to enhance the oxygen barrier property, drawability, maximum draw ratio, flex resistance, and impact strength under low humidity, and it is easy to reduce the adhesion to the metal roll during production.

[0035] Commercially available polyoxyalkylene (C) can also be used. Examples of representative commercially available products of polyoxyalkylene (C) include Alcox (trademark) E-75G, Alcox (trademark) L-11, Alcox (trademark) L-6, Alcox (trademark) EP1010N manufactured by Meisei Chemical Industry Co., Ltd., Peo (trademark) PEO-1, PEO-2 manufactured by Sumitomo Seika Chemicals Co., Ltd., and the like.

[0036] The content of polyoxyalkylene (C) is 0.1 to 10 parts by mass with respect to 100 parts by mass in total of components (A), (B), (C), and (D). When the content of polyoxyalkylene (C) is less than 0.1 part by mass or more than 10 parts by mass, the adhesion to the metal roll during production tends to increase, and the oxygen barrier property, drawability, maximum draw ratio, flex resistance, and impact strength under low humidity tend to decrease. The content of polyoxyalkylene (C) is 0.1 part by mass or more, preferably 0.5 part by mass or more, 10 parts by mass or less, preferably 8 parts by mass or less, and more preferably 5 parts by mass or less. When the content of polyoxyalkylene (C) is at least the above lower limit, it is likely to reduce the adhesion to the metal roll during production, and it is easy to enhance the drawability, maximum draw ratio, flex resistance, and impact strength under low humidity. Also, when the content is at most the above upper limit, the oxygen barrier property and the impact strength under low humidity are likely to be improved.

[0037] <Polyol plasticizer (D)> The resin composition of the present invention can optionally contain 0 to 5 parts by mass of polyol plasticizer (D) based on a total of 100 parts by mass of components (A), (B), (C), and (D). That is, the resin composition of the present invention may not contain polyol plasticizer (D), or may contain it in an amount exceeding 0 and not exceeding 5 parts by mass. The polyol plasticizer (D) can be used to improve the flexibility of the resin composition, and is particularly useful for controlling hardness and softness. On the other hand, when the content of the polyol plasticizer exceeds 5 parts by mass, the oxygen barrier property, flex resistance, impact strength under low humidity, and color tone are reduced, and sufficient oxygen barrier property, flex resistance, impact strength under low humidity, and color tone cannot be achieved. Moreover, during the production of the coated article, the drawability and maximum draw ratio are also likely to decrease, and the adhesion to the metal roll is also likely to increase. Therefore, in the present invention, 0 to 5 parts by mass of polyol plasticizer (D) can be used as needed. As will be described later, since extrusion molding is possible in the present invention, the resin composition can be produced using water or the like as a plasticizer without using a polyol plasticizer.

[0038] Examples of the polyol plasticizer (D) include sorbitol, maltitol, glycerol, mannitol, xylitol, erythritol, ethylene glycol, propylene glycol, etc. The polyol plasticizer (D) can be used alone or in combination of two or more. Among these, sorbitol is preferred from the viewpoint of suppressing the reduction of the oxygen barrier property, flex resistance, impact strength under low humidity, and color tone, while easily imparting flexibility.

[0039] When the resin composition of the present invention contains a polyol plasticizer (D), its content is preferably 0.1 part by mass or more and preferably 4 parts by mass or less. When the content of the polyol plasticizer (D) is at least the above lower limit, it is easy to enhance the flexibility of the resin composition, and when it is at most the above upper limit, it is easy to enhance the oxygen barrier property, drawability, maximum draw ratio, flex resistance, impact strength under low humidity, and color tone, and it is easy to reduce the adhesion to the metal roll during production.

[0040] <Resin composition> The resin composition of the present invention contains 50 to 98 parts by mass of modified starch (A), 2 to 50 parts by mass of polyvinyl alcohol (B), 0.1 to 10 parts by mass of polyoxyalkylene (C), and optionally 0 to 5 parts by mass of polyol plasticizer (D) based on a total of 100 parts by mass of components (A), (B), (C), and (D). Therefore, a coating having low adhesion to the metal roll during the production of the coating and excellent oxygen barrier property and flex resistance can be formed. Furthermore, the drawability and maximum draw ratio during the production of the coating are also high. That is, the resin composition of the present invention can form a coating that can be produced at a high conveyance speed, does not cause damage such as sticking to the metal roll during production, suppresses the penetration of liquids, etc. even after repeated bending, and has a high oxygen barrier property. Furthermore, since the resin composition of the present invention contains the above components (A) to (D) in a predetermined ratio, a film or sheet excellent in oxygen barrier property, impact strength under low humidity, and color tone can be formed. Therefore, the resin composition of the present invention can form a film or sheet that has a high oxygen barrier property, has a good appearance, and can prevent breakage, etc. even when the molded body is impacted during low humidity storage including a refrigerated environment. Therefore, the resin composition of the present invention can be suitably used as a material for food packaging and containers, etc.

[0041] The resin composition of the present invention may further contain a fatty acid having 12 to 22 carbon atoms and / or its fatty acid salt. Examples of the fatty acid having 12 to 22 carbon atoms and its fatty acid salt include stearic acid, calcium stearate, sodium stearate, palmitic acid, lauric acid, myristic acid, linoleic acid, behenic acid, and the like. Among these, from the viewpoint of processability, stearic acid, calcium stearate, and sodium stearate are preferable. The fatty acid having 12 to 22 carbon atoms and its fatty acid salt can be used alone or in combination of two or more.

[0042] When the resin composition of the present invention contains a fatty acid having 12 to 22 carbon atoms and / or its fatty acid salt, the content in the resin composition is preferably 0.01 to 3% by mass, more preferably 0.03 to 2% by mass, and still more preferably 0.1 to 1% by mass with respect to the mass of the resin composition. When the content of the fatty acid having 12 to 22 carbon atoms and / or its fatty acid salt is within the above range, it tends to be advantageous in terms of processability.

[0043] The resin composition of the present invention may further contain clay. Examples of the clay include synthetic or natural layered silicate clays such as montmorillonite, bentonite, beidellite, mica, hectorite, saponite, nontronite, sauconite, vermiculite, rectorite, magadiite, kenyaite, stevensite, and volkonskoite. The clay can be used alone or in combination of two or more.

[0044] When the resin composition of the present invention contains clay, the content in the resin composition is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and still more preferably 0.5 to 2% by mass with respect to the mass of the resin composition. When the content of the clay is within the above range, it tends to be advantageous in terms of transparency, color tone, and strength.

[0045] The resin composition of the present invention can contain a plasticizer (E) other than the polyol plasticizer (D). Examples of the plasticizer (E) include water, glyceryl trioleate, epoxidized linseed oil, epoxidized soybean oil, tributyl citrate, acetyltriethyl citrate, glyceryl triacetate, and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate. The plasticizer (E) can be used alone or in combination of two or more. Among these plasticizers (E), water is preferred from the viewpoint of obtaining good film-forming properties and coatability.

[0046] From the viewpoint of easily enhancing the film-forming properties and oxygen barrier properties of the resin composition, the water content (moisture content) in the resin composition is preferably 3 to 20% by mass, more preferably 4 to 18% by mass, still more preferably 7 to 15% by mass, based on the mass of the resin composition. The water content can be determined, for example, by measuring at 130°C for 60 minutes using a heated drying type moisture meter.

[0047] The resin composition of the present invention can further contain additives such as fillers, processing stabilizers, weather resistance stabilizers, colorants, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, flame retardants, other thermoplastic resins, lubricants, fragrances, defoaming agents, deodorants, extenders, release agents, mold release agents, reinforcing agents, crosslinking agents, fungicides, preservatives, and crystallization rate retardants, as needed.

[0048] In the resin composition of the present invention, the total content of the modified starch (A), polyvinyl alcohol (B), polyoxyalkylene (C), and polyol plasticizer (D) is preferably 60% by mass or more, more preferably 80% by mass or more, still 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 mass of the resin composition. When the total content of the components (A), (B), (C), and (D) is within the above range, it is easy to enhance the oxygen barrier properties, drawability, maximum draw ratio, flexural resistance, impact strength under low humidity, and color tone, and it is easy to reduce the adhesion to the metal roll during production.

[0049] The resin composition of the present invention may be in the form of pellets and films or sheets. When the resin composition of the present invention is used as a film or sheet, the thickness of the film is generally 5 to 100 μm, and the thickness of the sheet is generally 100 μm to 1000 μm. Further, the film or sheet may be a single layer or a multilayer (for example, a laminate described later).

[0050] [Method for producing resin composition] The resin composition of the present invention can be produced by a method including at least step (1) of mixing at least the modified starch (A), the polyvinyl alcohol (B), and the polyoxyalkylene (C) to obtain a mixture, step (2) of extruding the mixture, and step (3) of cooling and drying the extruded mixture.

[0051] Step (1) is at least a step of mixing at least the modified starch (A), the polyvinyl alcohol (B), and the polyoxyalkylene (C), and optionally the polyol plasticizer (D) and / or other components, such as the fatty acid having 12 to 22 carbon atoms and / or its fatty acid salt, the clay, the plasticizer (E), and the additive can be mixed together.

[0052] Step (1) is usually carried out using an extruder. In the extruder, each component is given a shear stress by a screw and homogeneously mixed while being heated by applying external heat to the barrel.

[0053] As the extruder, for example, a twin-screw extruder can be used. 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), the L / D ratio, may be, for example, 20 to 50. The rotation speed of the screw is preferably 80 rpm or more, more preferably 100 rpm or more. Also, the extrusion molding pressure is preferably 5 bar (0.5 MPa) or more, more preferably 10 bar (1.0 MPa) or more. Each component can be directly introduced into the extruder. Further, a premixed product of these components using a mixer may be introduced into the extruder.

[0054] In step (1), from the viewpoint of easily enhancing the film-forming property and oxygen barrier property of the resin composition, based on the mass of the mixture, the plasticizer (E) is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 10% by mass or more, particularly preferably 15% by mass or more, and most preferably 20% by mass or more as the lower limit, and preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less as the upper limit, and it is preferable to mix preferably water. Here, the mass of the mixture indicates the total mass of the mixture containing the plasticizer (E). In step (1), the plasticizer (E) may be introduced at the initial stage of extrusion, and the plasticizer (E) can be introduced before reaching the above heating temperature, for example, when it is 100°C or lower. The modified starch (A) can be subjected to a cooking treatment by a combination of moisture, heat, and shear stress to gelatinize (gel). Further, by separately introducing a plasticizer (E), preferably water, a water-soluble polymer such as polyvinyl alcohol (B) can be dissolved, the resin composition can be softened, and the modulus and brittleness can be reduced.

[0055] In step (1), the cooking treatment is preferably carried out by heating at a temperature of more than 100°C and 150°C or lower, more preferably 115°C or higher and 140°C or lower. Here, the cooking treatment is a treatment for crushing starch granules and gelatinizing them. The heating can be carried out by externally applying heat to the barrel of the extruder. By applying gradually changed temperatures to each barrel, heating can be performed up to the target temperature. When the cooking treatment is carried out at a temperature exceeding 120°C, it is advantageous in terms of processability.

[0056] In order to prevent foaming, the cooked mixture is preferably pushed forward toward the die while the temperature is decreased to preferably 85 - 120°C, more preferably 90 - 110°C. Further, foaming can be prevented and moisture can be removed by exhausting from the barrel.

[0057] The residence time in the extruder can be set according to the temperature profile and screw speed, and is preferably 1 - 2.5 minutes.

[0058] In the step (2) of extruding the mixture, the molten mixture that has been pushed forward in the extruder while being melt-kneaded is extruded from the die. The temperature of the die is preferably 85 to 120 °C, more preferably 90 to 110 °C.

[0059] In the step (3) of cooling and drying the extruded mixture (melt), the mixture (melt) can be extruded in the form of a film, sheet or strand.

[0060] When the mixture is extruded in the form of a film or sheet, the mixture can be extruded from a die for film or sheet forming, and then cooled and dried while being wound up by a take-up roller. It is preferable to cool between the die and the roller so as to prevent the mixture from adhering to the roller. A forming roll may be installed between the die and the roller. The material of the forming roll is, for example, rubber, resin or metal. For drying, the roll may be heated or dehumidified air may be supplied during winding. The dehumidified air can be used to expand the film or sheet when it exits the die in the case of the blowing tube method. It is also possible to prevent blocking of the film or sheet by entraining talc in the air stream.

[0061] When the mixture is extruded in the form of a strand, it can be extruded from a multi-hole strand nozzle and cut with a rotary cutter to form strands into pellets. In order to prevent sticking of the pellets, vibration can be applied periodically or constantly, and moisture in the pellets can be removed by hot air, dehumidified air or an infrared heater.

[0062] [Hydrous composition] The present invention includes a water-containing composition containing the resin composition and having a water content of 1 to 50% by mass. In a preferred embodiment of the present invention, in order to enhance the film-forming property of the resin composition, when coating the resin composition on paper or a film, water is added to the resin composition to prepare a water-containing composition. In the present invention, since the resin composition is composed of the above-described composition, stickiness due to the addition of water can be suppressed, the drawability, the maximum draw ratio, and the flexural fatigue resistance during the production of the coated article can be improved, and the adhesion to the metal roll can be reduced. The water content can be determined by measuring at 130 °C for 60 minutes using a heat drying type moisture meter, and can be measured, for example, by the method described in the examples. In this specification, the water-containing composition means all those having a water content measured by the above method of 1 to 50% by mass in the resin composition containing water. That is, the water-containing composition may be prepared by adding water to the produced resin composition, or if the water content of the resin composition itself is within the above range at the time of producing the resin composition, it is included in the concept of the water-containing composition. In other words, even when the resin composition contains water, it is included in the concept of the resin composition, but among the resin compositions, the resin composition specifically specified to have a water content of 1 to 50% by mass is referred to as the water-containing composition.

[0063] The water content of the water-containing composition of the present invention is preferably 5% by mass or more, more preferably 8% by mass or more, preferably 45% by mass or less, and more preferably 40% by mass or less. When the water content is within the above range, it is easy to enhance the oxygen barrier property, drawability, maximum draw ratio, and flexural fatigue resistance, and it is easy to reduce the adhesion to the metal roll during production.

[0064] In a preferred embodiment of the present invention, the water-containing composition of the present invention can be obtained by adding water to the resin composition and, for example, stirring and mixing. In order to prevent sticking between the resin compositions and adsorb water to the entire pellet, it is preferable to perform stirring while adding water in two or more portions. Further, in order to keep the water content constant, the water-containing composition may be stored in a sealed container.

[0065] [Coated article and method for producing the same] The present invention includes a coating obtained by coating a paper or film with the aqueous composition of the present invention. Despite having excellent oxygen barrier properties and biodegradability, the coating of the present invention can achieve both high drawability during production, which is inherently difficult to reconcile, and low adhesion to a metal roll, and is also excellent in flexural strength. Therefore, the coating of the present invention has high peelability from the metal roll and can be manufactured at a high conveyance speed while suppressing damage to the coating due to sticking to the metal roll, thereby improving the yield rate and production efficiency.

[0066] When coating the aqueous composition on paper, the paper is not particularly limited, and examples include kraft paper, fine paper, imitation paper, glassine paper, parchment paper, synthetic paper, white cardboard, manila board, milk carton base paper, cup base paper, ivory paper, silver paper, tissue paper, cardboard, rayon paper, and the like. The thickness of the paper in the coating is not particularly limited, preferably 1 to 500 μm, more preferably 10 to 300 μm. When the thickness of the paper in the coating is within the above range, the draw speed during coating production can be increased, and productivity is likely to be improved.

[0067] When coating the aqueous composition on a film, the film is not particularly limited, and examples include polyethylene terephthalate (PET) film, biaxially oriented polypropylene (BOPP) film, polyethylene (PE) film (preferably low-density polyethylene (LDPE) film), and polylactic acid film. The thickness of the film in the coating is not particularly limited, preferably 1 to 500 μm, more preferably 10 to 300 μm, and even more preferably 50 to 100 μm.

[0068] The thickness of the aqueous composition in the coating of the present invention is preferably 1 to 300 μm, more preferably 5 to 100 μm, and even more preferably 10 to 50 μm. When the thickness of the resin composition in the coating is within the above range, good film-forming properties and oxygen barrier properties are easily obtained, and sticking to the metal roll during production is easily suppressed.

[0069] The maximum draw ratio during the production of the coating of the present invention, that is, the maximum draw ratio of the aqueous composition, is preferably 5 or more, more preferably 8 or more, still more preferably 10 or more, and preferably 30 or less, more preferably 25 or less, still more preferably 20 or less. When the maximum draw ratio is within the above range, a coating excellent in adhesion between paper or film and the aqueous composition, oxygen barrier property, and flex resistance can be obtained with high productivity. The maximum draw ratio is represented by the following formula. (Maximum draw ratio) = (Maximum take-up speed) / (Flow rate at the die outlet of the extruder) (Flow rate at the die outlet of the extruder) = (Discharge amount) / ((Lip opening) × (Die width)) The maximum take-up speed is when coating the paper or film conveyed by the take-up machine with the aqueous composition discharged from the die outlet of the extruder. Under the condition of a constant discharge amount, the conveying speed (take-up speed) of the paper or film is increased in increments of 1.0 m / min, and it represents the maximum speed at which the melt curtain of the aqueous composition does not tear from the end even after holding for 10 seconds. The discharge amount, lip opening, and die width of the aqueous composition from the die outlet of the extruder may be adjusted as appropriate. The maximum draw ratio can be determined, for example, by the method described in the examples. Note that the maximum draw ratio can also be said to be a specific parameter of the aqueous composition because it varies depending on the properties of the aqueous composition. Here, the unit of each item described in the above formula is (maximum take-up speed) [m / s], (flow rate at the die outlet of the extruder) [m / s], (discharge amount) [m 3 / s], (lip opening) [m], and (die width) [m], and (maximum draw ratio) is [unitless].

[0070] The oxygen permeability (mL·20μm / m 2 ·atm·24hr) of the coating of the present invention at 23°C and 50% RH is preferably 5.0 or less, more preferably 4.0 or less, still more preferably 3.0 or less, and particularly preferably 2.5 or less. When the oxygen permeability of the coating is below the above upper limit, excellent oxygen barrier properties can be exhibited. Also, the oxygen permeability (mL·20μm / m 2·atm·24 hr) is usually 0.1 or more. The oxygen permeability of the coating can be measured by an oxygen permeation amount measuring device after storing and conditioning it at 23°C and 50% RH for two weeks, and can be measured, for example, by the method described in the examples. In the present specification, an improvement or increase in oxygen barrier properties indicates a reduction in oxygen permeability, and excellent oxygen barrier properties indicate low oxygen permeability.

[0071] The coating of the present invention is excellent in flex resistance. Flex resistance refers to the property of suppressing the penetration of liquids and the like from the folded portion after repeatedly folding the coating. For example, when folding, passing through a roll, and opening as described in the examples are taken as one set, it can be evaluated using the maximum number of sets without penetration of the dye into the paper surface. When the aqueous composition is coated on a film, it can be evaluated by the penetration of the dye into the film surface. In one embodiment of the present invention, the maximum number of sets of the coating of the present invention is preferably 5 or more, more preferably 6 or more, still more preferably 7 or more, and particularly preferably 8 or more. When the maximum number of sets is equal to or greater than the above lower limit, the flex resistance is excellent.

[0072] The method for producing the coating of the present invention is not particularly limited as long as it can coat the aqueous composition on paper or a film. In a preferred embodiment, the coating of the present invention can be produced by a method including a step of coating the aqueous composition on a film or paper conveyed by a take-up machine using an extruder (referred to as step (A)).

[0073] In one embodiment of the present invention, in step (A), the aqueous composition is charged into the extruder. Examples of the extruder include a single-screw extruder and a twin-screw extruder. The screw diameter of the extruder is, for example, 20 to 150 mm, the ratio of the extruder length (L) to the screw diameter (D), i.e., the L / D ratio, is, for example, 15 to 50, and the rotational speed of the screw is preferably 80 rpm or more, more preferably 100 rpm or more. The cylinder temperature in the extruder can be, for example, 80 to 120°C, preferably 90 to 110°C.

[0074] The water-containing composition fed into the extruder is plasticized and discharged from the die outlet. On the other hand, a paper or film is conveyed by a take-up machine, preferably a roller-type take-up machine. A coating is obtained by coating the conveyed paper or film with the water-containing composition discharged from the die outlet. The obtained coating is conveyed while being pressure-bonded to the paper or film between a plurality of rolls including a metal roll, and can be wound into a roll by a winder. Examples of the plurality of rolls include a pressure roll, a cast roll, a touch roll, etc. Usually, the cast roll is a metal roll (a roll made of metal). At this time, in the present invention, since the adhesion between the coated water-containing composition and the metal roll is low, the peelability from the metal roll is high, and it is possible to effectively prevent the water-containing composition in the coating from sticking to the metal roll and causing damage or the like. The adhesion of the coating to the metal roll can be evaluated by determining the adhesion of the water-containing sheet coated with waterproof paper on one side to the metal, as described in the examples. Also, in this specification, "coating" may be referred to as "coating".

[0075] In step (A), it is preferable that the draw ratio represented by the following formula (1) is 5 to 20. When a coating is produced with such a draw ratio, productivity is improved, and a coating excellent in adhesion between the paper or film and the water-containing composition and oxygen barrier properties is easily obtained. The flow rate at the die outlet of the extruder is represented by (discharge amount) / ((lip opening)×(die width)), as described above. When the discharge amount is expressed as the mass per unit time, the discharge amount is preferably 1 to 500 kg / hr, more preferably 5 to 200 kg / hr, the lip opening is preferably 0.01 to 5 mm, more preferably 0.1 to 1 mm, and the die width is preferably 100 to 3000 mm, more preferably 200 to 2000 mm. In the present invention, during the above manufacturing process, since the water in the water-containing composition evaporates, the water content of the water-containing composition in the obtained coating is reduced compared to before manufacturing. Draw ratio = (take-up speed of the take-up machine) / (flow rate at the die outlet of the extruder) (1)

[0076] [Multilayer structure and packaging material including the coating] The present invention encompasses a multilayer structure including the coating and one or more layers (X). Examples of the layer (X) include a film, paper, or an adhesive. When there are two or more layers (X), the layers (X) may be the same or different. The multilayer structure of the present invention has a plurality of layers (X), but the number of layers is not particularly limited and may be, for example, 3 to 10 layers. Examples of the film and paper include those exemplified as the film and paper in the section of [Coating and Method for Producing the Same].

[0077] Examples of the adhesive that may be included in the multilayer structure include acrylic adhesives, urethane adhesives, epoxy adhesives, vinyl acetate adhesives, ethylene-vinyl acetate adhesives, vinyl chloride adhesives, silicone adhesives, nitrile cellulose adhesives, phenolic adhesives, polyvinyl alcohol adhesives, melamine adhesives, styrene adhesives, and the like.

[0078] In a preferred embodiment of the present invention, the multilayer structure has a layer configuration laminated in the order of film / adhesive / hydrous composition / paper / adhesive / film. In this embodiment, the type of the film or paper is not particularly limited, but the film is preferably a polyethylene film.

[0079] The present invention encompasses a packaging material comprising the coating of the present invention or the multilayer structure. Since the packaging material is excellent in oxygen barrier properties, adhesion between the hydrous composition and paper or film, biodegradability, and flexural strength, it can be suitably used as a packaging material for food.

[0080] [Film or Sheet Composed of Resin Composition and Laminate Containing the Film or Sheet] The present invention encompasses a film or sheet composed of a resin composition (sometimes referred to as a resin composition film or resin composition sheet). As described above, the film or sheet of the present invention is excellent in oxygen barrier properties, impact strength under low humidity, and color tone.

[0081] In one embodiment of the present invention, the oxygen permeability of the film or sheet of the present invention at 23°C and 50% RH can be selected from the same range as the oxygen permeability of the coating. The meaning and measurement method of the oxygen permeability are also the same as those of the oxygen permeability in the coating.

[0082] In one embodiment of the present invention, the impact strength of the film or sheet of the present invention under low humidity is preferably 13 mN / μm or more, more preferably 15 mN / μm or more, still more preferably 18 mN / μm or more, and particularly preferably 20 mN / μm or more. When the impact strength under low humidity is equal to or higher than the above lower limit, the impact strength under low humidity is excellent, and breakage due to impact is less likely to occur. The impact strength under low humidity can be measured using a film impact tester after storing the film or sheet at 20°C and 33% RH for 2 weeks, and can be measured, for example, by the method described in the examples.

[0083] In one embodiment of the present invention, the b value (yellowness, YI) of the film or sheet of the present invention is preferably 18 or less, more preferably 15 or less, still more preferably 13 or less, and preferably -10 or more. When the b value is equal to or lower than the above upper limit, the yellowness of the film or sheet is reduced, and the color tone is easily improved. The b value can be measured using a color difference meter after storing the film or sheet at 23°C and 50% RH for 2 weeks, and can be measured, for example, by the method described in the examples.

[0084] The method for producing the film or sheet of the present invention is not particularly limited, and examples thereof include a method for obtaining a film or sheet from the resin composition described in the above section [Method for producing resin composition].

[0085] The present invention includes a laminate including a film or sheet and one or more layers (X). As the layer (X), for example, the same layers (X) as those described in the section [Multilayer structure and packaging material including the coating] can be used. In a preferred embodiment of the present invention, the laminate preferably has a layer structure laminated in the order of, for example, a resin composition film or sheet / adhesive layer / base material layer. The adhesive layer is made of an adhesive, and the base material layer is made of, for example, a film.

[0086] The manufacturing method of the laminate of the present invention is not particularly limited, but it is preferably manufactured by lamination. For example, when the laminate is a laminate having a resin composition film or sheet / adhesive layer / base material layer in this order, a method including a step of co-extruding the adhesive layer and the base material layer, and then a step of coating the adhesive layer side with a resin composition film or sheet can be mentioned. Other examples include a method including a step of extruding an adhesive layer and then a step of coating the adhesive layer between a resin composition film or sheet and a base material layer, and a step of coating a solution or dispersion of an adhesive on a resin composition film or sheet, or a base material layer with a gravure roll or the like and then drying, and then a step of bringing the adhesive layer side into close contact with the other resin composition film or sheet, or base material layer on which the adhesive is not applied.

[0087] In one embodiment of the present invention, in the step of co-extruding the adhesive layer and the base material layer, for example, a two-component two-layer co-extrusion casting film production facility (extruder manufactured by Plastic Engineering Laboratory) (extruder (1) for base material layer: single screw, screw diameter 40 mm, L / D = 32, extruder (2) for adhesive layer: single screw, screw diameter 32 mm, L / D = 26) can be used. The temperature conditions of the extruder may be appropriately set according to the thermoplastic resin to be used. For example, when extruding PET (polyethylene terephthalate) with the extruder (1) for the base material layer, the cylinder temperature can be 250 to 270 ° C, the adapter temperature can be 270 ° C, and the die temperature can be 275 ° C. Also, for example, when extruding a polyolefin with the extruder (2) for the adhesive layer, the cylinder temperature can be 175 to 270 ° C, the adapter temperature can be 270 ° C, and the die temperature can be 275 ° C. Also, the absolute value of the difference between the die temperature of the extruder (1) and the die temperature of the extruder (2) is preferably within 10 ° C, and more preferably 0 ° C. For example, when the optimum die temperature is different between the resin used for the extruder (1) and the resin used for the extruder (2), it is preferable to adopt the higher optimum die temperature and adjust the die temperature.

[0088] Subsequently, in the step of coating the adhesive layer side with a resin composition film or sheet, for example, a method can be adopted in which while pulling the adhesive layer side of the co-extruded laminate onto the resin composition film or sheet, it is coated and bonded with nip rolls. The pulling speed is preferably 1 to 10 m / min. Although the preferred extruder is described above, the type of extruder, screw diameter, and L / D can be changed as appropriate.

[0089] [Packaging Container and Method for Manufacturing the Same] The present invention includes a packaging container containing the film or sheet of the present invention or the laminate of the present invention, particularly a packaging tray or cup. The packaging container may consist only of the laminate of the present invention or may be a composite with other materials. For example, the laminate of the present invention can be thermoformed into a packaging container.

[0090] In one embodiment of the present invention, the packaging container of the present invention, particularly a packaging tray or cup, can be manufactured by a method including: a step of forming the resin composition using an extruder to obtain a film or sheet; a step of laminating one or more layers (X) on the obtained film or sheet by lamination to obtain a laminate; and a step of thermoforming the obtained laminate into a packaging tray or cup.

[0091] As the step of forming the resin composition using an extruder to obtain a film or sheet, for example, the film or sheet forming method described in the section of [Method for Manufacturing Resin Composition] above can be used. As the step of laminating one or more layers (X) on the obtained film or sheet by lamination to obtain a laminate, for example, the laminate manufacturing method described in the section of [Film or Sheet Composed of Resin Composition and Laminate Containing the Film or Sheet] above can be mentioned.

[0092] In the step of thermoforming the laminate into a packaging tray or cup, the thermoforming method is not particularly limited, but common methods include vacuum forming, pressure air forming, and as applications thereof, the plug assist method in which a plug is brought into contact with one side of the laminate for forming, and the so-called multi-mold forming method in which a male and female mold pair is brought into contact with both sides of the laminate for forming. Further, as a method for heating and softening the laminate before forming, non-contact heating or direct heating can be mentioned. As non-contact heating, radiant heating by an infrared heater or the like can be mentioned. Further, as direct heating, known heating methods such as hot plate heating in which the laminate is directly brought into contact with a hot plate can be applied.

[0093] The packaging container of the present invention is excellent as a packaging container because its impact strength is maintained even when stored under low humidity conditions. In a more preferred embodiment, since it has excellent oxygen barrier properties and color tone, it can be particularly preferably used as a packaging container for food.

Examples

[0094] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[0095] <Test method> (1) Measurement of maximum draw ratio The hydrated pellets 1 obtained in the examples and comparative examples were put into the single-screw extruder 2 shown in FIG. 1 and extruded from the die 3 for film formation. Next, the hydrated composition 4 extruded from the outlet of the die 3 was coated on the paper 5 conveyed by a roller-type take-up machine (not shown). The coating 6 obtained by coating was immediately pressure-bonded to the paper 5 (base material) through a pressure roll (rubber-made) 7a, a cast roll (metal-made) 7b, and a touch roll (rubber-made) 7c, and then wound up in a roll shape by a winder (not shown). Details of the single-screw extruder and operating conditions used, and the temperature profile (Table 1) are shown below. · Single-screw extruder: Extruder manufactured by Plastic Engineering Laboratory (40 mm diameter, L / D = 25) · Set temperature:

Table 1

[0096] Under the condition of a constant discharge rate, the conveying speed of the paper was increased in increments of 1.0 m / min from 1.0 m / min, and after holding for 10 seconds, the maximum speed at which the melt curtain did not tear from the end was recorded as the maximum take-up speed. The maximum draw ratio was calculated based on the following formula. (Maximum draw ratio) = (Maximum take-up speed) / (Flow rate at the die outlet of the extruder) (Flow rate at the die outlet of the extruder) = (Discharge rate) / ((Lip opening) × (Die width)) Note that when the maximum draw ratio is 5 or more, it can be evaluated as good.

[0097] (2) Measurement of oxygen permeability The coatings and sheets obtained in the examples and comparative examples were each stored at 23°C and 50% RH for two weeks for humidity conditioning, and then attached to an oxygen permeability measuring device to measure the oxygen permeability. The measurement conditions were as follows. Device: "MOCON OX-TRAN2 / 20" manufactured by Modern Controls Temperature: 23°C Humidity on the oxygen supply side and carrier gas side: 50% RH Oxygen pressure: 1.0 atm Carrier gas pressure: 1.0 atm

[0098] When the oxygen permeability is 5 (mL·20 μm / m 2 ·atm·24 hr) or less, it can be evaluated that the oxygen barrier property is good.

[0099] (3) Adhesion of the hydrated sheet to metal The adhesion of the coating to the metal roll during production was evaluated according to the following method. The water-containing pellets obtained in the examples and comparative examples were extruded from a die for film formation using a single-screw extruder, and then sandwiched between waterproof papers conveyed by a roller-type take-up machine, and wound into a roll using a winder to produce a water-containing sheet. The moisture content of the water-containing sheet was confirmed to be 28% by mass or more and less than 32% by mass by measuring at 130 °C for 60 minutes using a heating and drying type moisture meter "HR73" manufactured by METTLER TOLEDO Co., Ltd. After peeling off the waterproof paper on one side of the water-containing sheet with the moisture content maintained by sandwiching both sides with waterproof paper, it was immediately adhered to a metal plate subjected to chrome plating treatment, and at a temperature of 95 °C and a pressure of 50 kg / cm 2 It was pressed for 60 seconds. After leaving it to stand and cool at 20 °C for 3 minutes with both sides adhered to the metal plate and the waterproof paper, the water-containing sheet with the waterproof paper coated on one side on the metal plate was cut into strips with a width of 15 mm and a length of 10 cm. Next, the sheet cut into strips with a width of 15 mm and a length of 10 cm was peeled off from the 3 cm metal plate, sandwiched between the chucks of a tensile testing machine, and the load when peeling off from the metal plate at an angle of 90° was measured. · Waterproof paper: SUN ACE KENKYUSHO TGB70 tea (silicone-coated paper, thickness 70 μm) · Metal plate: A mirror-finished metal plate with a size of 100 × 100 mm and a thickness of 5 mm, on which a chrome plating treatment conforming to JIS H8615 was performed to a thickness of 50 μm or more, center line average roughness (Ra) = 0.04 μm · Press: "180C" manufactured by Imoto Seisakusho · Tensile testing machine: "INSTRON3367" manufactured by Instron Corporation, load cell 500 N

[0100] When the adhesion between the metal of the water-containing sheet with the waterproof paper coated on one side is 3 N / 15 mm or less, it can be evaluated that the adhesion between the coated material and the metal roll is low.

[0101] (4) Method for measuring the viscosity of polyvinyl alcohol (B) In accordance with JIS Z 8803 (falling ball viscometer) and JIS K 6726 (test method for polyvinyl alcohol), 4% aqueous solutions of polyvinyl alcohol in the examples and comparative examples were prepared, and the viscosity at 20 °C was measured using a Heppler viscometer, and the viscosity (20 °C) in the 4% aqueous solution of polyvinyl alcohol (B) was used.

[0102] (5) Evaluation method for flex resistance The coatings obtained in the examples and comparative examples were stored at 23 °C and 50% RH for 2 weeks, and the coated paper was cut into 10 × 10 cm sections. The resin surface was folded so that the area was bisected with the resin surface on the inside, and a 2 kg rubber roll (width: 45 mm, rubber hardness 80 Hs, No. 450 rubber roller manufactured by Taiyu Kikai Co., Ltd.) was passed over the paper surface of the folded part at a speed of 50 mm / second, and then the folded part was opened until it became flat. The above folding, passing the roll, and opening were repeated. A toluene - heptane mixed solution (toluene: heptane = 45:55, volume ratio) in which Sudan IV dye was dissolved at a concentration of 0.1% by weight was dropped onto the resin surface of the opened folded part, and after 10 seconds, the penetration of the dye into the paper surface was visually evaluated. Taking one set of folding, passing the roll, and opening, the maximum number of sets without penetration of the dye into the paper surface was used as the evaluation index for flex resistance.

[0103] (6) Evaluation method for color tone (b value) After storing the sheets obtained in the examples and comparative examples at 23 °C and 50% RH for 2 weeks, they were cut into 10 × 10 cm sections, and the b value (yellowness, YI) was measured using a color difference meter "ZE - 2000" manufactured by Nippon Denshoku Industries Co., Ltd.

[0104] (7) Evaluation method for impact strength under low humidity After storing the sheets obtained in the examples and comparative examples at 20 °C and 33% RH for 2 weeks, they were cut into 10 × 10 cm sections, and the impact strength was measured using a film impact tester manufactured by Toyo Seiki Co., Ltd.

[0105] (8) Materials used <High amylose modified starch (A - 1)> ·ECOFILM (trademark): Corn starch modified with propylene oxide, amylose content 70% by mass, manufactured by Ingredion <Low amylose modified starch (A-2)> ·National1658 (trademark): Corn starch modified with propylene oxide, amylose content 20% by mass, manufactured by Ingredion

[0106] <Polyvinyl alcohol (B)> ·ELVANOL (trademark) 71-30: Polyvinyl alcohol resin, saponification degree 99 mol% or more, viscosity 27 - 33 mPa·s (20 °C, 4% aqueous solution), manufactured by Kuraray ·Kuraray Poval (trademark) 5-98: Polyvinyl alcohol resin, saponification degree 98 mol%, viscosity 5 mPa·s (20 °C, 4% aqueous solution), manufactured by Kuraray ·Kuraray Poval (trademark) 5-88: Polyvinyl alcohol resin, saponification degree 88 mol%, viscosity 5 mPa·s (20 °C, 4% aqueous solution), manufactured by Kuraray ·Kuraray Poval (trademark) 3-98: Polyvinyl alcohol resin, saponification degree 98 mol%, viscosity 3 mPa·s (20 °C, 4% aqueous solution), manufactured by Kuraray

[0107] <Polyoxyalkylene (C)> ·Alcox (trademark) E-75G: Polyethylene oxide resin, weight average molecular weight 2,000,000, manufactured by Meisei Chemical Industry Co., Ltd. ·Alcox (trademark) L-11: Polyethylene oxide resin, weight average molecular weight 100,000, manufactured by Meisei Chemical Industry Co., Ltd. ·Alcox (trademark) L-6: Polyethylene oxide resin, weight average molecular weight 60,000, manufactured by Meisei Chemical Industry Co., Ltd. ·Alcox (trademark) EP1010N: Polyethylene oxide - polypropylene oxide random copolymer resin, weight average molecular weight 100,000, manufactured by Meisei Chemical Industry Co., Ltd.

[0108] <Polyol plasticizer (D)> ·Sorbitol SP: Sorbitol, manufactured by Bussan Food Science Co., Ltd.

[0109] <Clay> CLOISITE (registered trademark) 20A: Natural montmorillonite modified with dimethyldi (hydrogenated tallow) quaternary ammonium chloride, manufactured by Southern Clay Industries

[0110] <Example 1> (Resin composition) As raw materials, ECOFILM (trademark) (7.28 kg), National 1658 (2.43 kg), Kuraray Poival (trademark) 5-98 (200 g), and Alcox (trademark) L-11 (100 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. Figure 2 shows a schematic diagram of the twin-screw extruder used in Example 1, and the screw diameter, L / D ratio, rotation speed, operation mode, and temperature profile (Table 2) of the extruder are shown below.

[0111]

Table 2

[0112] Screw diameter: 27 mm L / D ratio: 48 Screw rotation speed 500 rpm Operation mode: Co-rotation (meshing self-wiping) mode

[0113] Specifically, the resulting mixture was fed into the barrel through the hopper at C1 at a rate of 3.5 kg / hour via the weight feeder of the twin-screw extruder. Water was injected into the barrel at a flow rate of 26 g / min through the liquid pump (L) at C4. The temperature ranges of C5 to C9 are the cooking zones, and complete gelatinization was completed within these zones. The strand die is located after C11. The resin composition was extruded from a multi-hole strand nozzle and cut with a rotary cutter to form strands into pellet shape. Since the pellets contained excess moisture, moisture was removed with hot air while constantly applying vibration to prevent sticking.

[0114] (Hydrous composition) Water was added to the obtained pellet-shaped resin composition until it reached 35% by mass based on the mass of the resin composition. When adding water, in order to prevent adhesion between the pellets and to allow the water to be uniformly absorbed throughout the pellets, the water was added in multiple portions while stirring with a tumbler mixer for 15 minutes. After stirring, it was placed in a polyethylene bag and sealed to prevent the water from evaporating, and left standing at room temperature for 6 hours. In this way, a water-containing composition (water-containing pellets) with a water content of 35% by mass was obtained. The water content was confirmed by measuring at 130 °C for 60 minutes using a heating and drying type moisture meter "HR73" manufactured by METTLER TOLEDO.

[0115] (Coated article) Using the same method as described in the above [(1) Measurement of the maximum draw ratio], a coated article was prepared by coating the water-containing composition onto paper so that the coating thickness was 20 μm, based on the maximum draw ratio, using the obtained water-containing pellets.

[0116] <Example 2> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 1, except that ECOFILM (trademark) (6.68 kg), National 1658 (2.23 kg), Kuraray Poval (trademark) 5-98 (1.00 kg), and Alcox (trademark) L-11 (100 g) were used as raw materials.

[0117] <Example 3> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 1, except that ECOFILM (trademark) (5.18 kg), National 1658 (1.73 kg), Kuraray Poval (trademark) 5-98 (3.00 kg), and Alcox (trademark) L-11 (100 g) were used as raw materials.

[0118] <Example 4> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 2, except that ELVANOL (trademark) 71-30 was used as the polyvinyl alcohol (B).

[0119] <Example 5> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 2, except that Kuraray POVAL (trademark) 3-98 was used as the polyvinyl alcohol (B).

[0120] <Example 6> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 2, except that Kuraray POVAL (trademark) 5-88 was used as the polyvinyl alcohol (B).

[0121] <Example 7> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 1, except that ECOFILM (trademark) (6.74 kg), National 1658 (2.25 kg), Kuraray POVAL (trademark) 5-98 (1.00 kg), and Alcox (trademark) L-11 (10 g) were used as raw materials.

[0122] <Example 8> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 1, except that ECOFILM (trademark) (6.00 kg), National 1658 (2.00 kg), Kuraray POVAL (trademark) 5-98 (1.00 kg), and Alcox (trademark) L-11 (1.00 kg) were used as raw materials.

[0123] <Example 9> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 2, except that Alcox (trademark) L-6 was used as the polyoxyalkylene (C).

[0124] <Example 10> A resin composition, a water-containing composition, and a coated article were obtained in the same manner as in Example 4, except that Alcox (trademark) E-75G was used as the polyoxyalkylene (C).

[0125] <Example 11> As a raw material, except that ECOFILM (trademark) (6.45 kg), National 1658 (2.15 kg), ELVANOL (trademark) 71-30 (1.00 kg), Alcox (trademark) E-75G (100 g) and sorbitol SP (300 g) were used, a resin composition, a water-containing composition and a coating were obtained in the same manner as in Example 1.

[0126] <Example 12> As polyoxyalkylene (C), except that Alcox (trademark) EP1010N was used, a resin composition, a water-containing composition and a coating were obtained in the same manner as in Example 2.

[0127] <Comparative Example 1> As a raw material, except that ECOFILM (trademark) (6.75 kg), National 1658 (2.25 kg) and Kuraray Poival (trademark) 5-98 (1.00 kg) were used, a resin composition, a water-containing composition and a coating were obtained in the same manner as in Example 1.

[0128] <Comparative Example 2> As a raw material, except that ECOFILM (trademark) (7.43 kg), National 1658 (2.48 kg) and Alcox (trademark) L-11 (100 g) were used, a resin composition, a water-containing composition and a coating were obtained in the same manner as in Example 1.

[0129] <Comparative Example 3> As a raw material, except that ECOFILM (trademark) (6.75 kg), National 1658 (2.25 kg), Kuraray Poival (trademark) 5-98 (1.00 kg) and Alcox (trademark) L-11 (5 g) were used, a resin composition, a water-containing composition and a coating were obtained in the same manner as in Example 1.

[0130] <Comparative Example 4> As a raw material, except that ECOFILM (trademark) (5.63 kg), National 1658 (1.88 kg), Kuraray Poival (trademark) 5-98 (1.00 kg) and Alcox (trademark) L-11 (1.50 kg) were used, a resin composition, a water-containing composition and a coating were obtained in the same manner as in Example 1.

[0131] <Comparative Example 5> A resin composition, a water-containing composition, and a coating were obtained in the same manner as in Example 1, except that ECOFILM (trademark) (5.93 kg), National 1658 (1.98 kg), Kuraray POVAL (trademark) 5-98 (1.00 kg), Alcox (trademark) L-11 (100 g), and Sorbitol SP (1.00 kg) were used as raw materials.

[0132] The results of measuring the content and average amylose content of the modified starch (A), the saponification degree, viscosity (20 °C) and content in a 4% aqueous solution of polyvinyl alcohol (B), the brand, weight average molecular weight and content of polyoxyalkylene (C), the content of polyol plasticizer (D), the maximum draw ratio of the resin composition, the oxygen permeability of the coating, the adhesion of the water-containing sheet to the metal, and the maximum number of bending sets of the coating are shown in Table 3.

[0133]

Table 3

[0134] As shown in Table 3, the coatings obtained in Examples 1 to 12 had a lower oxygen permeability compared to Comparative Examples 2, 4, and 5, a lower adhesion of the water-containing sheet to the metal compared to Comparative Examples 1 and 3, and a larger maximum number of bending sets compared to Comparative Examples 1 to 5. Furthermore, it was also confirmed that the coatings obtained in Examples 1 to 12 had a high maximum draw ratio of 8 or more. Therefore, it was found that the resin composition of the present invention can form a coating with low adhesion to a metal roll during production and excellent oxygen barrier properties and flex resistance. Furthermore, it was also found that the maximum draw ratio during production was high.

[0135] <Example 13> As raw materials, ECOFILM (trademark) (6.75 kg), National 1658 (2.25 kg), ELVANOL (trademark) 71-30 (0.90 kg), and Alcox (trademark) L-11 (100 g) were used, and the resin composition was not formed into pellets but was formed into a sheet shape through a 300 mm coat hanger die and then dried by passing it over a metal roll heated to 90°C. Otherwise, a resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 1. Furthermore, 200 μm PET sheets (Novaclear A3020 manufactured by Mitsubishi Chemical Corporation) were bonded to both sides of the obtained resin composition sheet with an adhesive (a 10:1 (mass ratio) mixture of Takelac A520 and Takenate A50 manufactured by Mitsui Chemicals, Inc.) to obtain a multilayer sheet. Using a pressure air vacuum molding machine (FKS-0632-20 manufactured by Asano Laboratory), at a heater temperature of 600°C, a sheet surface temperature of 120°C, a heating time of 10 seconds, and a molding pressure of 3 kg / cm 2 The thermal molding of the multilayer sheet was carried out under these conditions to form it into a cup (inner diameter 70 mm, height 110 mm) shape. No breakage, uneven thickness, cloudiness, etc. were observed in the obtained molded body.

[0136] <Example 14> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that Kuraray Poval (trademark) 5-98 was used as the polyvinyl alcohol (B).

[0137] <Example 15> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that as raw materials, ECOFILM (trademark) (6.82 kg), National 1658 (2.27 kg), ELVANOL (trademark) 71-30 (0.90 kg), and Alcox (trademark) L-11 (10 g) were used.

[0138] <Example 16> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that ECOFILM (trademark) (6.08 kg), National 1658 (2.03 kg), ELVANOL (trademark) 71-30 (0.90 kg), and Alcox (trademark) L-11 (1.00 kg) were used as raw materials.

[0139] <Example 17> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that Alcox (trademark) L-6 was used as the polyoxyalkylene (C).

[0140] <Example 18> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that Alcox (trademark) E-75G was used as the polyoxyalkylene (C).

[0141] <Example 19> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that Alcox (trademark) EP1010N was used as the polyoxyalkylene (C).

[0142] <Example 20> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that ECOFILM (trademark) (6.53 kg), National 1658 (2.18 kg), ELVANOL (trademark) 71-30 (0.90 kg), Alcox (trademark) L-11 (100 g), and sorbitol SP (300 g) were used as raw materials.

[0143] <Comparative Example 6> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that ECOFILM (trademark) (6.83 kg), National 1658 (2.28 kg), and ELVANOL (trademark) 71-30 (0.90 kg) were used as raw materials.

[0144] <Comparative Example 7> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that ECOFILM (trademark) (6.68 kg), National 1658 (2.23 kg), ELVANOL (trademark) 71-30 (0.90 kg), and CLOISITE (registered trademark) 20A (200 g) were used as raw materials.

[0145] <Comparative Example 8> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that ECOFILM (trademark) (7.43 kg), National 1658 (2.48 kg), and Alcox (trademark) L-11 (100 g) were used as raw materials.

[0146] <Comparative Example 9> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that ECOFILM (trademark) (6.82 kg), National 1658 (2.27 kg), ELVANOL (trademark) 71-30 (0.90 kg), and Alcox (trademark) L-11 (5 g) were used as raw materials.

[0147] <Comparative Example 10> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that ECOFILM (trademark) (5.70 kg), National 1658 (1.90 kg), ELVANOL (trademark) 71-30 (0.90 kg), and Alcox (trademark) L-11 (1.50 kg) were used as raw materials.

[0148] <Comparative Example 11> A resin composition sheet with a thickness of 100 μm was obtained in the same manner as in Example 13, except that ECOFILM (trademark) (6.00 kg), National 1658 (2.00 kg), ELVANOL (trademark) 71-30 (0.90 kg), Alcox (trademark) L-11 (100 g), and Sorbitol SP (1.00 kg) were used as raw materials.

[0149] The content of modified starch (A) and its average amylose content, the saponification degree of polyvinyl alcohol (B), the viscosity (20 °C) and content in a 4% aqueous solution, the brand, weight average molecular weight and content of polyoxyalkylene (C), the content of polyol plasticizer (D), the content of viscosity, and the hue (b value), oxygen permeability and impact strength under low humidity of the resin composition sheet were measured, and the results are shown in Table 4.

[0150]

Table 4

[0151] As shown in Table 4, the resin composition sheets obtained in Examples 13 to 20 had a lower b value compared to Comparative Examples 7 and 11, a lower oxygen permeability compared to Comparative Examples 8, 10 and 11, and a higher impact strength under low humidity compared to Comparative Examples 6, 8 to 10. Therefore, it was found that the resin composition of the present invention can form a sheet excellent in oxygen barrier properties, impact strength under low humidity and color tone.

Explanation of Symbols

[0152] 1... water-containing pellet, 2... single-screw extruder, 3... die for film formation, 4... water-containing composition, 5... paper, 6... coating, 7a... pressure roll (rubber), 7b... cast roll (metal), 7c... touch roll (rubber), 8... twin-screw extruder, 9... hopper, 10... liquid addition nozzle, 11... resin thermometer, 12... resin pressure gauge, 13... adapter, 14... die

Claims

1. 50 to 97 parts by weight of modified starch (A) having an average amylose content of 50% by weight or more; 2 to 40 parts by weight of polyvinyl alcohol (B), 0.1 to 10 parts by weight of polyoxyalkylene (C) and optionally 0 to 5 parts by weight of a polyol plasticizer (D) wherein the total content of (A), (B), (C) and (D) is 100 parts by mass.

2. The resin composition according to claim 1, wherein the total content of the modified starch (A), the polyvinyl alcohol (B), the polyoxyalkylene (C) and the polyol plasticizer (D) is 80 mass% or more based on the mass of the resin composition.

3. The resin composition according to claim 1 or 2, wherein the modified starch (A) is at least one selected from the group consisting of etherified starch, esterified starch, cationic starch and crosslinked starch.

4. The resin composition according to any one of claims 1 to 3, wherein the modified starch (A) is at least one selected from the group consisting of etherified starch having a hydroxyalkyl group having 2 to 6 carbon atoms and esterified starch having a structural unit derived from a dicarboxylic acid anhydride.

5. The resin composition according to any one of claims 1 to 4, wherein the polyvinyl alcohol (B) has a viscosity of 1 to 50 mPa·s in a 4% aqueous solution at 20°C as measured in accordance with JIS Z 8803.

6. A water-containing composition comprising the resin composition according to any one of claims 1 to 5, wherein the water-containing composition has a water content of 1 to 50 mass%.

7. A coated article comprising paper or film coated with the water-containing composition according to claim 6.

8. A multi-layer structure comprising the coating of claim 7 and one or more layers (X).

9. A packaging material comprising the covering material according to claim 7 or the multilayer structure according to claim 8.

10. The water-containing composition according to claim 6 is coated on a film or paper conveyed by a take-off machine using an extruder, and in the coating process, a water-containing composition according to formula (1); Draw ratio = (take-off speed of take-off machine) / (flow rate at the die outlet of the extruder) (1) The method for producing a coating according to claim 7, wherein the draw ratio represented by is 5 to 20.

11. A film or sheet comprising the resin composition according to any one of claims 1 to 5.

12. A laminate comprising the film or sheet of claim 11 and one or more layers (X).

13. A packaging tray or cup comprising the film or sheet of claim 11 or the laminate of claim 12.

14. 14. A method for producing a packaging tray or cup according to claim 13, comprising the steps of: molding the resin composition according to any one of claims 1 to 5 using an extruder to obtain a film or sheet; laminating one or more layers (X) onto the obtained film or sheet by lamination to obtain a laminate; and thermoforming the obtained laminate into a packaging tray or cup.

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