Adhesive resin composition

Abstract

To provide an adhesive resin composition excellent in heat resistance and excellent in adhesive strength to both a polyvinyl alcohol resin layer and a biodegradable resin layer.SOLUTION: The adhesive resin composition of the present invention contains 3-24 pts.mass of a polyol (B) and 0-40 pts.mass of starch or modified starch (C) based on 100 pts.mass of a biodegradable polyester resin (A). The total amount of the polyol (B) and the starch or the modified starch (C) is 44 pts.mass or less. The biodegradable polyester resin (A) has an elongation at break of 50% or more as measured according to ISO 527-1. The polyol (B) has a glass transition temperature of -10°C or higher.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an adhesive resin composition, a laminate including an adhesive layer comprising the adhesive resin composition, and a food packaging material and a coffee capsule including the adhesive layer or the laminate. [Background technology]

[0002] Plastics are widely used as packaging materials because of their high moldability, strength, water resistance, transparency, etc. However, plastics are poorly biodegradable, and if they are dumped in the natural world after use, they may remain for a long time and cause environmental destruction. In response to this, biodegradable resins that are biodegraded or hydrolyzed in soil or water and are useful for preventing environmental pollution have been attracting attention in recent years, and packaging materials using biodegradable resin compositions have been put into practical use. For example, Patent Document 1 describes a resin composition used in packaging materials that contains a biodegradable polyester such as polylactic acid, a polysaccharide such as starch, and a polyhydric alcohol such as glycerin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-335934 A Summary of the Invention [Problem to be solved by the invention]

[0004] Such biodegradable packaging materials usually have a multi-layer structure, and a specific example thereof is a laminate including a biodegradable resin layer, an adhesive layer, and a polyvinyl alcohol-based resin layer. However, according to the study by the present inventors, when the adhesive layer is formed from a conventional resin composition, it is difficult to exhibit sufficient adhesive strength to both the biodegradable resin layer and the polyvinyl alcohol-based resin layer. Furthermore, it was found that the conventional resin composition has poor heat resistance, and coloring that may occur at high temperatures cannot be suppressed in some cases.

[0005] Therefore, an object of the present invention is to provide an adhesive resin composition which has excellent heat resistance and excellent adhesive strength to both a polyvinyl alcohol-based resin layer and a biodegradable resin layer, a laminate including an adhesive layer comprising the adhesive resin composition, and a food packaging material and a coffee capsule which include the adhesive layer or the laminate. [Means for solving the problem]

[0006] As a result of intensive research by the present inventors to achieve the above object, it was found that the above problem can be solved by setting the contents of the biodegradable polyester (A), the polyol (B), and the starch or modified starch (C) in the adhesive resin composition, and the total amount of the above (B) and (C) within specific ranges, and further, the breaking elongation of the biodegradable polyester (A) and the glass transition temperature of the polyol (B) within specific ranges, and thus the present invention was completed. That is, the present invention includes the following preferred aspects.

[0007] [1] An adhesive resin composition comprising, based on 100 parts by mass of a biodegradable polyester-based resin (A), 3 to 24 parts by mass of a polyol (B) and 0 to 40 parts by mass of starch or modified starch (C), wherein the total amount of the polyol (B) and the starch or modified starch (C) is 44 parts by mass or less, the biodegradable polyester-based resin (A) has a breaking elongation of 50% or more measured in accordance with ISO 527-1, and the polyol (B) has a glass transition temperature of -10°C or higher. [2] The adhesive resin composition according to [1], wherein the biodegradable polyester resin (A) has a melting point of 70°C or higher. [3] The adhesive resin composition according to [1] or [2], wherein the biodegradable polyester resin (A) contains an aromatic-aliphatic copolymer polyester resin. [4] The adhesive resin composition according to [3], wherein the aromatic-aliphatic copolymer polyester resin is polybutylene adipate terephthalate. [5] The adhesive resin composition according to any one of [1] to [4], wherein the polyol (B) is at least one selected from the group consisting of maltitol, sorbitol, and trehalose. [6] The adhesive resin composition according to any one of [1] to [5], which does not contain starch or modified starch (C). [7] A laminate comprising an adhesive layer comprising the adhesive resin composition according to any one of [1] to [6]. [8] The laminate according to [7], comprising a biodegradable resin layer, the adhesive layer, and a polyvinyl alcohol-based resin layer, in this order. [9] A food packaging material comprising an adhesive layer comprising the adhesive resin composition according to any one of [1] to [6], or the laminate according to [7] or [8].

[10] A coffee capsule comprising an adhesive layer comprising the adhesive resin composition according to any one of [1] to [6], or the laminate according to [7] or [8]. Effect of the Invention

[0008] The adhesive resin composition of the present invention has excellent heat resistance and excellent adhesive strength to both a polyvinyl alcohol-based resin layer and a biodegradable resin layer, and therefore can be suitably used as a packaging material for food and the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Adhesive resin composition] The adhesive resin composition of the present invention contains 100 parts by mass of biodegradable polyester (A), 3 to 24 parts by mass of polyol (B), and 0 to 40 parts by mass of starch or modified starch (C), the total amount of polyol (B) and starch or modified starch (C) is 44 parts by mass or less, the biodegradable polyester (A) has a breaking elongation of 50% or more measured in accordance with ISO 527-1, and the glass transition temperature (sometimes abbreviated as Tg) of polyol (B) is -10°C or higher. In this specification, the biodegradable polyester resin (A) may be referred to as "component (A)", the polyol (B) may be referred to as "component (B)", the starch or modified starch (C) may be referred to as "component (C)", and polyvinyl alcohol may be abbreviated as PVA. In this specification, the upper limit and the lower limit can be combined arbitrarily.

[0010] The present inventors have conducted research into the interlayer adhesion of laminates and coloring due to heat, and have surprisingly found that, in an adhesive resin composition, if the contents of components (A), (B) and (C) [sometimes abbreviated as components (A)-(C)], the total amount of components (B) and (C), the elongation at break of component (A), and the Tg of component (B) are within specific ranges, the adhesive strength to both the PVA-based resin layer and the biodegradable resin layer can be improved, and heat resistance can also be improved, and coloring at high temperatures can be suppressed. This is presumably because a specific amount of component (A) having an elongation at break of 50% or more can improve the toughness and strength of the composition itself, and can exhibit high adhesive strength to the biodegradable resin layer; a specific amount of component (B) having a Tg of -10°C or more can exhibit high adhesive strength to the PVA-based resin layer while suppressing bleed-out and a decrease in toughness; and a specific amount of component (C) can improve heat resistance while suppressing a decrease in toughness. In this specification, the adhesive strength can be evaluated by a peel test, and means the peel strength between the adhesive resin composition (adhesive layer) and other layers such as a PVA-based resin layer and a biodegradable resin layer. Here, the failure of the adhesive layer before peeling in the peel test is called "cohesive failure", and in the case of "cohesive failure", the adhesive strength is evaluated based on the strength at the time of cohesive failure. Therefore, the adhesive strength includes the adhesive strength of the adhesive resin composition to other layers, and the strength and toughness of the composition itself. In addition, in this specification, heat resistance refers to the property of being able to suppress coloration even at high temperatures, and can be evaluated, for example, by the method described in the Examples.

[0011] <Biodegradable polyester resin (A)> The adhesive resin composition of the present invention contains a biodegradable polyester resin (A) having a breaking elongation of 50% or more measured according to ISO 527-1. By containing such a biodegradable polyester resin (A), the toughness of the adhesive resin composition itself is increased while maintaining biodegradability, and the adhesive strength to the biodegradable resin layer and the PVA resin layer can be improved. Biodegradability refers to a property that can be chemically decomposed by the action of, for example, hydrolysis, enzymatic decomposition, microbial decomposition, etc., and preferably refers to a material that meets the biodegradability standard specified in EN13432 or ASTM6400. That is, a material is considered to be biodegradable if, when placed in a compost environment, 90% of the material disintegrates into particles with an average size of less than 2 mm within 12 weeks, and at least 60% of the material in the case of ASTM6400, or at least 90% of the material in the case of EN13432, decomposes into carbon dioxide and / or water after 6 months.

[0012] The biodegradable polyester resin (A) has a breaking elongation of 50% or more. If the breaking elongation is less than 50%, the toughness of the composition itself is insufficient, and the adhesive strength tends to decrease. The breaking elongation of the biodegradable polyester resin (A) is 50% or more, preferably 100% or more, more preferably 200% or more, even more preferably 400% or more, even more preferably 600% or more, particularly preferably 800% or more, and particularly preferably 900% or more. If the breaking elongation is equal to or greater than the above lower limit, the toughness increases, and therefore the adhesive strength can be improved. The upper limit of the breaking elongation is usually 5000% or less, preferably 3000% or less, and more preferably 2000% or less. If the breaking elongation is equal to or less than the above upper limit, the adhesive composition can be prevented from decreasing in elastic modulus and maximum strength, and therefore the adhesive strength can be prevented from decreasing. The breaking elongation can be measured in accordance with ISO 527-1, for example, by the method described in the Examples. When two or more biodegradable polyester resins (A) are used in combination, the breaking elongation of the mixture of the biodegradable polyester resins used is measured, and the breaking elongation obtained is regarded as the breaking elongation of the biodegradable polyester resin (A).

[0013] The biodegradable polyester resin is not particularly limited as long as it has a breaking elongation of 50% or more and has the above-mentioned biodegradability, and may be a petroleum-derived biodegradable resin or a biologically derived biodegradable resin. Examples of the biodegradable polyester resin include aliphatic polyester resins, aromatic-aliphatic copolymer polyester resins, and aromatic polyester resins. The biodegradable polyester resin preferably contains at least one selected from the group consisting of aliphatic polyester resins and aromatic-aliphatic copolymer polyester resins, and more preferably contains an aromatic-aliphatic copolymer polyester resin from the viewpoint of having high biodegradability and easily increasing adhesive strength and heat resistance.

[0014] Examples of the aliphatic polyester resin include polyalkylene monocarboxylates and polyalkylene dicarboxylates.

[0015] Examples of polyalkylene monocarboxylates include ring-opening polymers of lactones (cyclic esters), and specific examples thereof include polycaprolactone (abbreviated as PCL).

[0016] Polyalkylene dicarboxylate is a polycondensate of an aliphatic diol (or a derivative thereof) and an aliphatic dicarboxylic acid (or a derivative thereof). Examples include polybutylene succinate (abbreviated as PBS), polyethylene succinate (abbreviated as PES), poly(butylene succinate-co-butylene adipate), etc.

[0017] Aromatic-aliphatic copolymer polyester resins are polyester resins having both aromatic and aliphatic moieties, and are condensates of aliphatic or aromatic diols (or their derivatives) and aromatic or aliphatic dicarboxylic acids (or their derivatives). Examples include polybutylene adipate terephthalate (abbreviated as PBAT), polybutylene succinate terephthalate (PBST), and polyethylene adipate terephthalate (PEAT). PBAT is preferred from the viewpoint of being highly biodegradable and easily increasing adhesive strength and heat resistance. These biodegradable polyester resins may be used alone or in combination of two or more kinds.

[0018] The biodegradable polyester resin (A) may be produced by a conventional method, or a commercially available product may be used. Commercially available biodegradable polyester resin (A) includes polycaprolactone (PCL) sold by Union Carbide under the trade name Tone (e.g., Tone P-300, P-700, P-767, and P-787, each having a weight average molecular weight of about 10,000, 40,000, 43,000, and 80,000), or polycaprolactone (PCL) sold by Perstorf under the trade name CAPA 6800 and CAPA FB 100 (each having a molecular weight of 80,000 and 100,000 Daltons); Polyethylene succinate (PES) and polybutylene succinate (PBS) sold under the trade name Skygreen™ SG100 by SK Chemicals (Korea), such as Ecoflex™ by BASF (Germany), or EnPOL™ G8060 and EnPOL™ 8000 by IreChemical Ltd (Seoul), and the like.

[0019] The biodegradable polyester resin (A) may be a modified biodegradable polyester resin or an unmodified biodegradable polyester resin. The modified biodegradable polyester resin is not particularly limited, but may be, for example, a modified biodegradable polyester resin obtained by graft-modifying a biodegradable polyester resin with an unsaturated carboxylic acid and / or its derivative. The unsaturated carboxylic acid used as a modifier is not particularly limited, but examples thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, etc. Furthermore, the derivative of the unsaturated carboxylic acid is not particularly limited, but examples thereof include acid anhydrides, esters, amides, imides, metal salts, etc.

[0020] Specific examples of the derivative of an unsaturated carboxylic acid include maleic anhydride, himic anhydride, itaconic anhydride, citraconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, glycidyl acrylate, maleic acid monoethyl ester, maleic acid diethyl ester, itaconic acid monomethyl ester, itaconic acid diethyl ester, acrylamide, methacrylamide, maleic acid monoamide, maleic acid diamide, maleic acid-N-monoethylamide, maleic acid-N,N-diethylamide, maleic acid-N,N-monobutylamide, maleic acid-N,N-dibutylamide, fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monobutylamide, fumaric acid-N,N-dibutylamide, maleimide, N-butylmaleimide, N-phenylmaleimide, sodium acrylate, sodium methacrylate, potassium acrylate, and potassium methacrylate. These unsaturated carboxylic acids and / or their derivatives can be used alone or in any combination and ratio of two or more. Among these, maleic acid or its anhydride is particularly preferred because of its low electron density and high reactivity.

[0021] The content of the modifier is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, even more preferably 0.03 mass% or more, and is preferably 3.0 mass% or less, more preferably 1.0 mass% or less, even more preferably 0.2 mass% or less, relative to the mass of the modified biodegradable polyester resin.

[0022] Since the adhesive resin composition of the present invention is an alloy containing specific amounts of components (A) to (C), it can exhibit excellent adhesive strength and heat resistance to the PVA resin layer and the biodegradable resin layer without modifying the biodegradable polyester resin (A). Therefore, in a preferred embodiment of the present invention, the biodegradable polyester resin (A) is preferably an unmodified biodegradable polyester resin. When it is unmodified, it is possible to prevent a decrease in biodegradability due to modification and also to avoid the complication of production due to modification.

[0023] In a preferred embodiment of the present invention, the melting point of the biodegradable polyester resin (A) is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, even more preferably 100°C or higher, and particularly preferably 105°C or higher. When the melting point of the biodegradable polyester resin (A) is above the above lower limit, the thermoformability is more easily improved, so that the occurrence of wrinkles and the like of the obtained laminate is more easily suppressed or prevented, and the appearance is more likely to be good. The upper limit of the melting point is preferably 300°C or lower, more preferably 200°C or lower, even more preferably 150°C or lower, even more preferably 140°C or lower, and particularly preferably 130°C or lower. When the melting point is below the above upper limit, the thermoformability is more easily improved, so that the obtained laminate is easily molded into a predetermined shape. The melting point can be measured by a differential scanning calorimeter (DSC), for example, by the method described in the Examples.

[0024] In one embodiment of the present invention, the melt mass flow rate (MFR) of the biodegradable polyester resin (A) is preferably 1.0 g / 10 min or more, more preferably 3.0 g / 10 min or more, even more preferably 5.0 / 10 min or more, even more preferably 10 g / 10 min or more, and preferably 30 g / 10 min or less, more preferably 25 g / 10 min or less, and even more preferably 20 g / 10 min or less. When the MFR of the biodegradable polyester resin (A) is within the above range, it is easy to increase the adhesive strength, heat resistance, and thermoformability. The MFR can be measured in accordance with ISO1133 under conditions of 200 ° C. and 2.16 kg.

[0025] In one embodiment of the present invention, the weight average molecular weight (Mw) of the biodegradable polyester resin (A) is preferably 10,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more, and is preferably 500,000 or less, more preferably 200,000 or less, and even more preferably 100,000 or less. When the Mw of the biodegradable polyester resin (A) is within the above range, the adhesive strength, thermoformability, and heat resistance are easily improved.

[0026] In one embodiment of the present invention, the number average molecular weight (Mn) of the biodegradable polyester resin (A) is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 20,000 or more, and is preferably 200,000 or less, more preferably 100,000 or less, and even more preferably 50,000 or less. When the Mn of the biodegradable polyester resin (A) is within the above range, the adhesive strength, thermoformability, and heat resistance are easily improved. The Mw and Mn of the biodegradable polyester resin (A) can be determined by gel permeation chromatography (GPC) measurement and conversion into standard polystyrene, for example, by the method described in the Examples.

[0027] In one embodiment of the present invention, the content of the biodegradable polyester resin (A) is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and even more preferably 65% ​​by mass or more, based on the mass of the adhesive resin composition, and may be, for example, 75% by mass or more or 85% by mass or more. When the content of the biodegradable polyester resin (A) is equal to or more than the above lower limit, the adhesive strength to the biodegradable resin layer is easily increased due to the improvement of the affinity to the biodegradable resin layer. In addition, the adhesive strength to the biodegradable resin layer and the PVA-based resin layer is easily increased due to the improvement of the toughness and strength of the composition itself. The content of the biodegradable polyester resin (A) is preferably 96.5% by mass or less, more preferably 95% by mass or less, and even more preferably 92% by mass or less, based on the mass of the adhesive resin composition. When the content of the biodegradable polyester resin (A) is equal to or less than the above upper limit, the adhesive strength to the PVA-based resin layer is easily increased.

[0028] [Polyol (B)] The adhesive resin composition of the present invention contains a polyol (B). The polyol (B) contained in the adhesive resin composition has a glass transition temperature (Tg) of -10°C or higher and a content of 3 to 24 parts by mass, so that the adhesive strength and heat resistance can be improved. The polyol may be derived from an artificial or natural product, is preferably derived from a natural product, and is more preferably a sugar alcohol.

[0029] In the adhesive resin composition of the present invention, the Tg of the polyol (B) is -10°C or higher. If the Tg of the polyol (B) is less than -10°C, the polyol (B) tends to bleed out, etc., and the adhesive strength tends to decrease. The Tg of the polyol (B) is -10°C or higher, preferably -5°C or higher, more preferably 0°C or higher, even more preferably 5°C or higher, even more preferably 15°C or higher, and particularly preferably 25°C or higher. If the Tg of the polyol (B) is above the above lower limit, bleed out, etc. can be suppressed, and the adhesive strength can be increased. The Tg of the polyol (B) is preferably 150°C or lower, more preferably 130°C or lower, even more preferably 100°C or lower, even more preferably 80°C or lower, and particularly preferably 60°C or lower. Even if the Tg of the polyol (B) is below the above upper limit, the adhesive strength is easily improved. The Tg of the polyol (B) can be measured by a differential scanning calorimeter (DSC), for example, by the method described in the Examples. When two or more polyols are used in combination, the Tg of the polyol mixture used is measured, and the obtained Tg is regarded as the Tg of polyol (B).

[0030] Examples of the polyol (B) having a Tg of -10°C or higher include maltitol, sorbitol, trehalose, lactitol, and galactitol. From the viewpoint of easily increasing the adhesive strength and heat resistance, the polyol (B) is preferably at least one selected from the group consisting of maltitol, sorbitol, and trehalose, and is preferably at least one selected from the group consisting of maltitol and sorbitol, and is more preferably maltitol. In addition, these polyols may be polyol derivatives to which alkylene oxides such as ethylene oxide and propylene oxide are added, so long as they have a Tg of -10°C or higher.

[0031] The content of polyol (B) is 3 to 24 parts by mass based on 100 parts by mass of biodegradable polyester resin (A). If the content of polyol (B) is less than 3 parts by mass and exceeds 24 parts by mass, the adhesive strength tends to decrease. The content of polyol (B) is 3 parts by mass or more, preferably 4 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 6 parts by mass or more, and may be 8 parts by mass or more or 9 parts by mass or more, based on 100 parts by mass of biodegradable polyester (A). If the content of polyol (B) is equal to or more than the above lower limit, the adhesive strength to the PVA resin layer can be increased. The content of polyol (B) is 24 parts by mass or less, preferably 22 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 18 parts by mass or less, based on 100 parts by mass of biodegradable polyester (A), and may be 16 parts by mass or less, 14 parts by mass or less, or 12 parts by mass or less. When the content of the polyol (B) is equal to or less than the above upper limit, the toughness and strength of the adhesive resin composition itself tend to increase, and the adhesive strength can be improved.

[0032] [Starch or modified starch (C)] The adhesive resin composition of the present invention may contain starch or modified starch (C). That is, the adhesive resin composition of the present invention may or may not contain starch or modified starch (C).

[0033] Examples of starches include starches derived from cassava, corn, potato, sweet potato, sago, tapioca, sorghum, beans, bracken, lotus, water chestnut, wheat, rice, oats, arrowroot, peas, etc. Among these, starches derived from corn and cassava are preferred, and starches derived from corn are more preferred. The starches can be used alone or in combination of two or more kinds.

[0034] The modified starch is preferably at least one selected from the group consisting of, for example, etherified starch, esterified starch, cationized starch, crosslinked starch, and amidated starch.

[0035] Examples of the 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 having 2 to 6 carbon atoms. Other examples of the etherified starch include cetyl bromide, lauryl bromide, epoxidized soybean fatty alcohol, epoxidized linseed fatty alcohol, etherified starch having a structural unit derived from a glycidyl ether such as allyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, decane glycidyl ether, lauryl phenyl glycidyl ether, myristoyl glycidyl ether, cetyl glycidyl ether, palmityl glycidyl ether, stearyl glycidyl ether, and linolyl glycidyl ether (starch to which the glycidyl ether is bonded by etherification), and allyl etherified starch. The hydroxyalkyl etherified starch is preferably hydroxyethyl etherified starch, hydroxypropyl etherified starch, hydroxybutyl etherified starch, etc., and may be obtained by reacting starch with an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide, etc. The average number of hydroxy groups used for modification is preferably 0.05 to 2 per glucose unit in starch. The etherified starch having a structural unit derived from glycidyl ether is preferably an etherified starch having a structural unit derived from glycidyl ether having 2 to 24 carbon atoms, and more preferably an etherified starch having a structural unit derived from glycidyl ether having 6 to 24 carbon atoms.

[0036] Examples of the esterified starch 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 maleic anhydride, phthalic anhydride, and succinic anhydride; esterified starches having structural units derived from alkanoic acid carboxylic acid anhydrides, such as octanoic acid acetic anhydride, decanoic acid acetic anhydride, lauric acid acetic anhydride, and myristic acid acetic anhydride; esterified starches having structural units derived from octenylsuccinic anhydride and nonylsuccinic anhydride; Examples of the starch ester include starch esters having structural units derived from alkyl or alkenyl dicarboxylic anhydrides such as hydrates, decyl succinic anhydride, dodecenyl succinic anhydride, octenyl maleic anhydride, nonyl maleic anhydride, decyl maleic anhydride, and dodecenyl maleic anhydride; starch esters having structural units derived from oxo acids such as starch nitrate, starch phosphate, and starch urea phosphate; xanthate ester; and starch acetoacetate ester. The number of carbon atoms of the carboxylic acid, dicarboxylic anhydride, and alkyl or alkenyl dicarboxylic acid may be, for example, 2 to 24, or 2 to 6 or 7 to 24. As the alkyl or alkenyl dicarboxylic anhydride, octenyl succinic anhydride or octenyl maleic anhydride is preferable.

[0037] Examples of the cationic starch include a reaction product of starch with 2-diethylaminoethyl chloride, and a reaction product of starch with 2,3-epoxypropyltrimethylammonium chloride.

[0038] Examples of the crosslinked starch include formaldehyde crosslinked starch, epichlorohydrin crosslinked starch, phosphate crosslinked starch, and acrolein crosslinked starch.

[0039] Examples of the amidated starch include starches to which an aliphatic amine, such as n-dodecylamine, n-hexadecylamine, n-octadecylamine, cocoamine, tallow amine, hydrogenated N-tallow-1,3-diaminopropane, N-hydrogenated tallow-1,3-diaminopropane, or N-oleyl-1,3-diaminopropane, is bonded by amidation.

[0040] The starch or modified starch (C) may preferably have a moisture content of 5 to 15% by mass.

[0041] As the starch or modified starch (C), the above modified starch is preferred from the viewpoint of easily increasing the adhesive strength and heat resistance, and is preferably at least one selected from the group consisting of hydroxyalkyl etherified starch (preferably etherified starch having a hydroxyalkyl group having 2 to 6 carbon atoms), etherified starch having a structural unit derived from glycidyl ether (preferably etherified starch having a structural unit derived from glycidyl ether having 6 to 24 carbon atoms), esterified starch having a structural unit derived from dicarboxylic anhydride (preferably esterified starch having a structural unit derived from dicarboxylic anhydride having 2 to 6 carbon atoms), and esterified starch having a structural unit derived from alkyl or alkenyl dicarboxylic anhydride (preferably esterified starch having a structural unit derived from alkyl or alkenyl dicarboxylic anhydride having 6 to 24 carbon atoms). These modified starches can be used alone or in combination of two or more kinds. In this specification, the number of carbon atoms described before "starch" represents the number of carbon atoms of a group substituted with one hydroxyl group in starch (a group formed by modifying one hydroxyl group in starch). For example, an etherified starch having a hydroxyalkyl group having 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.

[0042] In one embodiment of the present invention, the starch or modified starch (C) may have an average amylose content of preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, and preferably 90% by mass or less, more preferably 70% by mass or less, even more preferably 50% by mass or less, even more preferably 40% by mass or less, and particularly preferably 30% by mass or less. When the average amylose content is within the above range, the thermoformability and adhesiveness of the starch or modified starch (C) and the adhesive resin composition itself are easily improved. The amylose content can be measured, for example, by the iodine coloring method described in "Starch 50 No.4 158-163 (1998)". In addition, when one type of starch or modified starch is used, the average amylose content indicates the amylose content of the one type of starch or modified starch, and when two or more types of starch or modified starch are used, it is the weighted average of the amylose contents of the two or more types of starch or modified starch. Moreover, the starch or modified starch (C) used may be commercially available.

[0043] In one embodiment of the present invention, the weight average molecular weight (Mw) of starch or modified starch (C) may be preferably 5,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, and may be preferably 800,000 or less, more preferably 600,000 or less, even more preferably 400,000 or less, even more preferably 200,000 or less. When the Mw of starch or modified starch (C) is within the above range, it is easy to improve the thermoformability and adhesiveness of starch or modified starch (C) and the adhesive resin composition itself. The Mw of starch or modified starch (C) can be measured, for example, using GPC (gel permeation chromatography).

[0044] The content of starch or modified starch (C) is 0 to 40 parts by mass based on 100 parts by mass of biodegradable polyester resin (A). When the content of starch or modified starch (C) exceeds 40 parts by mass, the adhesive strength and heat resistance tend to decrease. In one embodiment of the present invention, the content of starch or modified starch (C) is 40 parts by mass or less, preferably 35 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, especially more preferably 3 parts by mass or less, and especially more preferably 1 part by mass or less. When the content of starch or modified starch (C) is less than the above upper limit, it is easy to suppress the decrease in toughness of the composition itself, and it is possible to develop high adhesive strength and to suppress the decrease in heat resistance. In addition, in a preferred embodiment of the present invention, the adhesive resin composition of the present invention does not contain starch or modified starch (C). When starch or modified starch (C) is not contained, it is easy to develop excellent adhesive strength and heat resistance. In another embodiment of the present invention, the content of starch or modified starch (C) is preferably 1% by mass or more, more preferably 3% by mass or more, and preferably 35% by mass or less. The content of starch or modified starch (C) within the above range is advantageous from the viewpoints of biodegradability, adhesive strength, and heat resistance.

[0045] In the adhesive resin composition of the present invention, the total amount of polyol (B) and starch or modified starch (C) is 44 parts by mass or less based on 100 parts by mass of biodegradable polyester (A). If the total amount exceeds 44 parts by mass, the adhesive strength and heat resistance tend to decrease. The total amount of polyol (B) and starch or modified starch (C) is 44 parts by mass or less, preferably 43 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, particularly preferably 25 parts by mass or less, particularly more preferably 20 parts by mass or less, and particularly more preferably 15 parts by mass or less. If the total amount of polyol (B) and starch or modified starch (C) is less than the above upper limit, it is easy to suppress the decrease in toughness of the composition itself, and high adhesive strength can be expressed, and the decrease in heat resistance can be suppressed. The total amount of the polyol (B) and the starch or modified starch (C) is preferably 3 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 5 parts by mass or more, based on 100 parts by mass of the biodegradable polyester (A). When the total amount is equal to or more than the lower limit, the adhesive strength is easily increased.

[0046] <Adhesive resin composition> The adhesive resin composition of the present invention contains 3 to 24 parts by mass of polyol (B) and 0 to 40 parts by mass of starch or modified starch (C) based on 100 parts by mass of biodegradable polyester resin (A), the total amount of component (B) and component (C) is 44 parts by mass or less, the breaking elongation of biodegradable polyester (A) is 50% or more, and the Tg of polyol (B) is -10 ° C. or more, so that it has excellent heat resistance, and can suppress or prevent coloration even at high temperatures (for example, even when exposed to high temperatures during production or molding), and has excellent adhesive strength to both polyvinyl alcohol resin layer and biodegradable resin layer. Therefore, the adhesive resin composition of the present invention can be suitably used as a packaging material for food and the like. Furthermore, in one embodiment of the present invention, the adhesive resin composition of the present invention also has excellent thermoformability, and the obtained laminate can be easily molded into a predetermined shape.

[0047] In one embodiment of the present invention, the total amount of components (A) to (C) contained in the adhesive resin composition of the present invention may be, from the viewpoint of easily increasing adhesive strength and heat resistance, preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, even more preferably 80 mass% or more, particularly preferably 90 mass% or more, and particularly preferably 95 mass% or more, for example 97 mass% or more or 99 mass% or more, based on the mass of the adhesive resin composition. In addition, the adhesive resin composition of the present invention may be composed of a biodegradable polyester (A), a polyol (B), and starch or modified starch (C).

[0048] In one embodiment of the present invention, the adhesive strength of the adhesive resin composition of the present invention to a PVA-based resin layer is preferably 5N / 25mm or more, more preferably 10N / 25mm or more, even more preferably 15N / 25mm or more, even more preferably 20N / 25mm or more, particularly preferably 30N / 25mm or more, particularly preferably 40N / 25mm or more, and particularly preferably 50N / 25mm or more. When the adhesive strength is equal to or greater than the lower limit, the strength of the resulting laminate is easily improved. The adhesive strength to a PVA-based resin layer is usually 200N / 25mm or less. The adhesive strength to a PVA-based resin indicates the peel strength between an adhesive layer and a PVA resin layer in a multilayer sheet including an adhesive layer made of an adhesive resin composition and a PVA resin layer. The peel strength can be measured using a peel tester according to JIS K 6854-2 under conditions of a peel angle of 180°, a tensile speed of 100mm / min, and an environmental temperature of 23°C. The adhesive strength to a PVA-based resin can be determined, for example, by the method described in the Examples.

[0049] In one embodiment of the present invention, the adhesive strength of the adhesive resin composition of the present invention to the biodegradable resin layer is preferably 5N / 25mm or more, more preferably 15N / 25mm or more, even more preferably 25N / 25mm or more, even more preferably 30N / 25mm or more, particularly preferably 40N / 25mm or more, particularly preferably 50N / 25mm or more, and particularly preferably 60N / 25mm or more. When the adhesive strength is equal to or greater than the lower limit, the strength of the resulting laminate is easily improved. The adhesive strength to the biodegradable resin layer is usually 200N / 25mm or less. The adhesive strength to the biodegradable resin layer indicates the peel strength between the adhesive layer and the biodegradable resin layer in a multilayer sheet comprising an adhesive layer made of the adhesive resin composition and a biodegradable resin layer. The peel strength can be measured using a peel tester according to JIS K 6854-2 under the conditions of a peel angle of 180°, a tensile speed of 100mm / min, and an environmental temperature of 23°C. The adhesive strength to the biodegradable resin layer can be determined, for example, by the method described in the Examples.

[0050] The adhesive resin composition of the present invention may contain a biodegradable polyester other than component (A) having an elongation at break of less than 50%, as long as the elongation at break of the biodegradable polyester resin (A) in the adhesive resin composition does not fall below 50%.

[0051] The biodegradable polyester having a breaking elongation of less than 50% may be, for example, PHA. PHA is a polymer having hydroxyalkanoic acid as a monomer unit. More specifically, it may be polyglycolic acid, polylactic acid (sometimes abbreviated as PLA), poly(3-hydroxyalkanoate) (abbreviated as P3HA), poly(4-hydroxyalkanoate), etc.

[0052] P3HA is a polymer mainly composed of 3-hydroxyalkanoic acid as a monomer unit. Examples of 3-hydroxyalkanoic acid include 3-hydroxybutyrate, 3-hydroxypropionate, 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyheptanoate, and 3-hydroxyoctanoate. P3HA may be a homopolymer or a copolymer containing two or more monomer units. In addition, when P3HA is a copolymer, it may be a copolymer of two or more 3-hydroxyalkanoic acids, or a copolymer of one or more 3-hydroxyalkanoic acids and a 4-hydroxyalkanoic acid such as 4-hydroxybutyrate.

[0053] Specific examples of P3HA include poly(3-hydroxybutyrate) homopolymer (abbreviated as PHB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviated as PHBH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviated as PHBV), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviated as 3HB4HB).

[0054] The biodegradable polyester having a breaking elongation of less than 50% is not particularly limited as long as it is added in such a range that the breaking elongation of the biodegradable polyester resin (A) in the adhesive resin composition does not fall below 50%, but may be, for example, 20 mass% or less, preferably 10 mass% or less, more preferably 5 mass% or less, and preferably 0 mass% or more, for example 0.1 mass% or 1 mass% or more, relative to the mass of the adhesive resin composition.

[0055] The adhesive resin composition of the present invention may contain a polyol other than component (B) whose Tg is less than -10°C or whose Tg is not observed, so long as the Tg of the polyol (B) in the adhesive resin composition does not fall below -10°C.

[0056] Examples of polyols having a Tg of less than -10°C or no observable Tg include glycerol, xylitol, mannitol, erythritol, pentaerythritol, and dipentaerythritol.

[0057] The polyol having a Tg of less than -10°C or no observable Tg is not particularly limited as long as it is added in a range in which the Tg of the polyol (B) in the adhesive resin composition does not fall below -10°C, but may be, for example, 20 mass% or less, preferably 10 mass% or less, more preferably 5 mass% or less, and preferably 0 mass% or more, for example 0.1 mass% or 1 mass% or more, relative to the mass of the adhesive resin composition.

[0058] The adhesive resin composition of the present invention may contain additives other than component (A), component (B) and component (C) within the scope of not impairing the purpose and effect of the present invention. Examples of additives include fillers, processing stabilizers, weathering stabilizers, colorants, ultraviolet absorbers, heat stabilizers, light stabilizers, antioxidants, antistatic agents, flame retardants, plasticizers, lubricants, fragrances, foaming agents, deodorants, extenders, release agents, mold release agents, reinforcing materials, fungicides, preservatives, crystallization rate retarders, and resins other than biodegradable polyester resins. These additives can be used alone or in combination of two or more.

[0059] The filler may be added from the viewpoint of easily increasing hardness and stiffness, easily preventing blocking, etc. Examples of the filler include inorganic fillers such as mica, kaolin, kaolinite, clay, talc, acid clay, silica, alumina, diatomaceous earth, bentonite, montmorillonite, wood-bush clay, frog's eye clay, rosewood, alumite, china clay, feldspar, asbestos, perlite, calcium carbonate, magnesium hydroxide, carbon black, vermiculite, titanium oxide, mica, zirconium oxide, boron nitride, aluminum nitride, shirasu, glass, and glass fiber, and organic fillers such as urea-formalin resin and melamine-formalin resin. The fillers can be used alone or in combination of two or more.

[0060] Examples of the other resins include polyphenylene ether resins, polycarbonate resins, polyamide resins such as nylon 66 and nylon 11, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, styrene resins such as polystyrene, (meth)acrylate resins such as polymethyl methacrylate resins, etc. The other resins can be used alone or in combination of two or more.

[0061] The content of the additives is not particularly limited as long as they are added within a range that does not impair the purpose and effects of the present invention, but may be, for example, 20 mass% or less, preferably 10 mass% or less, more preferably 5 mass% or less, and preferably 0 mass% or more, for example 0.1 mass% or 1 mass% or more, relative to the mass of the adhesive resin composition.

[0062] The form of the adhesive resin composition of the present invention is not particularly limited, and may be a pellet, a sheet, or a film. That is, the adhesive resin composition may be a pellet, a sheet, or a film that contains or consists of the adhesive resin composition. The thickness of the sheet or film can be appropriately selected depending on the application, and is preferably 5 to 1000 μm, more preferably 10 to 500 μm. The thickness of the film or sheet can be measured with a thickness meter, for example, by the method described in the Examples. In addition, the adhesive resin composition of the present invention may contain a solvent and may be in the form of a solution or dispersion, and the solvent may be a known solvent in which the components in the composition can be dissolved or dispersed.

[0063] The method for producing the adhesive resin composition of the present invention is not particularly limited, but may be, for example, a method of mixing the biodegradable polyester resin (A), the polyol (B), and optionally the starch or modified starch (C) and additives. A conventional mixer, preferably a melt kneader, can be suitably used for mixing. The temperature during mixing or kneading is preferably 40°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher, and preferably 300°C or lower, more preferably 200°C or lower. The rotation speed of the kneader is preferably 20 rpm or higher, more preferably 40 rpm or higher, and usually 1000 ppm or lower, preferably 500 rpm or lower. In addition, each of these components may be premixed using a mixer or the like and then introduced into the melt kneader.

[0064] In one embodiment of the present invention, the adhesive resin composition can be obtained by melt kneading using an extruder. As the extruder, a twin screw extruder can be preferably used. The twin screw extruder may be either co-rotating or counter-rotating. The rotation speed of the screw can be selected from the same range as the rotation speed of the kneader described above. The cylinder temperature can be selected from the temperature range during mixing or kneading described above. Each component can be directly introduced into the extruder.

[0065] The molten mixture that has been forced through the extruder while being melt-kneaded is extruded from a die. The die temperature may be preferably 100 to 200° C., more preferably 100 to 150° C. The extrusion speed is preferably 1 to 10 kg / h, more preferably 2 to 5 kg / h.

[0066] The extruded mixture (melt) can be extruded into a sheet, film or strand shape, during which the mixture (melt) is cooled and dried.

[0067] When the mixture is extruded in the form of strands, it can be extruded through a strand nozzle with multiple holes and cut with a rotary cutter to form the strands into pellets. To prevent the pellets from sticking together, vibration can be applied periodically or constantly, and moisture in the pellets can be removed by hot air, dehumidified air, or an infrared heater.

[0068] When the mixture is extruded into a sheet or film, the mixture can be extruded through a film forming die and then cooled and dried while being taken up by a take-up roller. It is preferable to cool the mixture between the die and the roller so as to prevent the mixture from adhering to the roller. The solution or dispersion of the adhesive resin composition of the present invention may be formed into a sheet or film by a conventional film forming method (for example, cast film formation, etc.).

[0069] The adhesive resin composition (for example, a pellet-like adhesive resin composition) may be formed into a sheet or film by a conventional method such as extrusion molding, compression molding, or press molding.

[0070] [Laminate] The present invention encompasses a laminate comprising an adhesive layer comprising the adhesive resin composition of the present invention. The laminate of the present invention may comprise one or more adhesive layers of the present invention, and when it comprises two or more layers, the compositions of the adhesive layers may be the same or different. The form of the adhesive layer is not particularly limited, and may be, for example, a film or sheet. The laminate may comprise layers other than the adhesive layer of the present invention. Examples of the other layers include a resin layer, paper, and other adhesive layers. The resin layer is a resin layer having a different composition from the adhesive layer.

[0071] The resin constituting the resin layer is not particularly limited, and examples thereof include polyester-based resins such as polyethylene terephthalate (PET), polyolefin-based resins such as polypropylene (PP) [preferably biaxially oriented polypropylene (BOPP)] and polyethylene (PE) [preferably low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE)], ethylene-vinyl acetate copolymers, polyvinyl alcohol-based resins such as ethylene-α-olefin copolymers, biodegradable resins such as biodegradable polyester-based resins, and resins obtained by modifying these with a modifier such as maleic anhydride. The resin layer can be used alone or in combination of two or more kinds. The adhesive layer in the laminate of the present invention contains the adhesive resin composition, and therefore can exhibit excellent adhesive strength to both the biodegradable resin layer and the polyvinyl alcohol-based resin layer. Therefore, the laminate of the present invention preferably contains a biodegradable resin layer and / or a polyvinyl alcohol-based resin layer as the resin layer, and more preferably contains a biodegradable resin layer and a polyvinyl alcohol-based resin layer. Furthermore, the laminate of the present invention can improve heat resistance, biodegradability, and gas barrier properties by containing an adhesive layer.

[0072] The biodegradable resin layer is not particularly limited as long as it contains a biodegradable resin as a main component, and examples thereof include the biodegradable polyester resins described above in the section <Biodegradable polyester resin (A)>, as well as casein, modified starch, cellulose acetate, PLA, PHB, PHBV, 3HB4HB, and PHBH. Among these, from the viewpoint of easily increasing the adhesive strength with the adhesive layer and biodegradability, the biodegradable resin is preferably at least one selected from the group consisting of the biodegradable polyester resin (A), PLA, PHB, PHBV, 3HB4HB, and PHBH, and more preferably at least one selected from the group consisting of PLA, PHB, PHBV, 3HB4HB, PHBH, PBAT, PBS, and PCL.

[0073] The PVA resin layer is not particularly limited as long as it contains a PVA resin as a main component. The PVA resin is a resin containing a vinyl ester polymer or copolymer (collectively referred to as a vinyl alcohol polymer). The vinyl alcohol polymer is a polymer containing a vinyl alcohol unit as a monomer unit. The vinyl alcohol polymer is obtained by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer, which is a raw material monomer, and the vinyl alcohol polymer after saponification may contain a vinyl ester unit in addition to the vinyl alcohol unit. The vinyl alcohol polymer may be a modified vinyl alcohol copolymer containing a monomer unit other than the vinyl alcohol unit and the vinyl ester unit, obtained by saponifying a copolymer obtained by copolymerizing a vinyl ester monomer, which is a raw material monomer, with another monomer. The vinyl ester monomer used as a raw material monomer for the vinyl alcohol polymer is not particularly limited, and examples thereof include vinyl acetate and the like. The other monomers are not particularly limited, and examples thereof include α-olefins such as ethylene, propylene, n-butene, and isobutylene. The PVA-based resin preferably contains, as the vinyl alcohol-based polymer, at least one selected from the group consisting of an unmodified vinyl alcohol polymer and an α-olefin-vinyl alcohol copolymer, and more preferably contains an unmodified vinyl alcohol polymer.

[0074] In one embodiment of the present invention, the PVA-based resin layer may contain a plasticizer, for example, polyol (eg, trehalose, etc.), in addition to the PVA-based resin. In this specification, "main component" means a component that is contained in more than 50 mass % of the layer, and the amount may be, for example, 55 mass % or more, 70 mass % or more, or 90 mass % or more.

[0075] The paper is not particularly limited, and examples thereof include kraft paper, double-bleached kraft paper, wood-free paper, imitation paper, glassine paper, parchment paper, synthetic paper, white cardboard, Manila cardboard, milk carton base paper, cup base paper, ivory paper, and white silver paper.

[0076] The laminate of the present invention includes a laminate including a biodegradable resin layer / adhesive layer in this order; a laminate including a PVA-based resin layer / adhesive layer in this order; and a laminate including a biodegradable resin layer / adhesive layer / PVA-based resin layer in this order. Among these, the laminate of the present invention is preferably a laminate including a biodegradable resin layer / adhesive layer / PVA-based resin layer in this order (sometimes referred to as laminate A). These laminates may include layers other than the biodegradable resin layer and the PVA-based resin layer between or on the outside of each layer, but it is preferable that the layers do not include the other layers between each layer, that is, that each layer is adjacent to each other. For example, it is preferable that the laminate A has a biodegradable resin layer, an adhesive layer, and a PVA-based resin adjacent to each other (that is, in contact) in this order. The laminate A has excellent adhesive strength, heat resistance, and biodegradability between the biodegradable resin layer and the adhesive layer, and between the adhesive layer and the PVA-based resin layer.

[0077] The thickness of the adhesive layer in the laminate of the present invention can be appropriately selected according to the type of laminate, and is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 200 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less. When the thickness of the adhesive layer is within the above range, it is easy to increase the adhesive strength, heat resistance, biodegradability, and gas barrier property. The above thickness of the adhesive layer indicates the thickness of one layer when two or more adhesive layers are included in the laminate.

[0078] The thickness of the other layer in the laminate of the present invention can be appropriately selected depending on the type of the laminate, and is not particularly limited, but is preferably 10 to 3000 μm, more preferably 15 to 1000 μm, and even more preferably 20 to 500 μm. When the thickness of the other layer is within the above range, the adhesive strength, heat resistance, biodegradability, and gas barrier property are easily improved. When two or more other layers are included in the laminate, the thickness of the other layer indicates the thickness of one layer.

[0079] The thickness of the laminate of the present invention is not particularly limited, but is preferably 20 μm or more, more preferably 50 μm or more, even more preferably 100 μm or more, even more preferably 200 μm or more, particularly preferably 300 μm or more, and is preferably 5000 μm or less, more preferably 3000 μm or less, and even more preferably 1000 μm or less. When the thickness of the laminate is within the above range, the strength, heat resistance, biodegradability, and gas barrier property of the laminate are easily improved.

[0080] In one embodiment of the present invention, the thickness of the adhesive layer in the laminate A of the present invention is the same as the thickness of the adhesive layer described above. The thickness of the biodegradable resin layer in the laminate A is not particularly limited, but is preferably 50 μm or more, more preferably 100 μm or more, even more preferably 200 μm or more, and preferably 1000 μm or less, more preferably 500 μm or less. The thickness of the PVA-based resin layer in the laminate A is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, and preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 200 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less. When the thickness of each layer is within the above range, it is easy to increase the adhesive strength, heat resistance, biodegradability, and gas barrier property. The thickness of each layer (biodegradable resin layer, adhesive layer, and PVA-based resin layer) in the laminate A indicates the thickness of one layer when the laminate A has two or more layers of the same layer. The thickness of each layer and the thickness of the laminate can be measured using a thickness meter, for example, by the method described in the Examples.

[0081] Specific examples of the layer structure of the laminate A of the present invention are as follows. Biodegradable resin layer / adhesive layer / PVA resin layer; Biodegradable resin layer / adhesive layer / PVA resin layer / adhesive layer / biodegradable resin layer; Biodegradable resin layer / regrind layer / adhesive layer / PVA resin layer / adhesive layer / regrind layer / biodegradable resin layer; Biodegradable resin layer / adhesive layer / PVA resin layer / adhesive layer / paper.

[0082] The laminate of the present invention can be produced by laminating another layer such as a resin layer and an adhesive layer by a conventional method such as a coextrusion molding method (coextrusion lamination method, coextrusion sheet molding method, coextrusion inflation molding method, coextrusion blow molding method, etc.), a coinjection molding method, an extrusion lamination method, a dry lamination method, etc. For example, it may be a method of coextruding or laminating another layer and an adhesive layer, or a method of forming a film of an adhesive resin composition on another layer. When laminating, the adhesive resin composition may be applied to the surface of the other layer, or extrusion coated on the surface of the other layer.

[0083] The method for producing the laminate A, which is a preferred embodiment of the present invention, is not particularly limited, but is preferably a method in which a pellet-shaped adhesive resin composition, a pellet-shaped biodegradable resin (or a biodegradable resin composition) forming the biodegradable resin layer, and a pellet-shaped PVA-based resin (or a PVA-based resin composition) forming the PVA-based resin layer are co-extruded by a co-extruder. More specifically, each resin (or each resin composition) can be introduced into the hopper of each extruder, melt-kneaded, and co-extruded by a feed block die. The cylinder temperature of each extruder may be appropriately selected according to the melting temperature of the resin (or the resin composition). Although not limited, for example, the cylinder temperature of the extruder for the adhesive layer may be, for example, 120 to 300°C, preferably 150 to 250°C, the cylinder temperature of the extruder for the biodegradable resin layer may be, for example, 150 to 300°C, preferably 180 to 250°C, and the cylinder temperature of the extruder for the PVA-based resin layer may be, for example, 150 to 300°C, preferably 190 to 260°C.

[0084] In one embodiment of the present invention, the laminate of the present invention is also excellent in heat resistance, and for example, coloring at high temperatures during production or molding can be suppressed or prevented. The laminate of the present invention is also excellent in thermoformability and can be easily molded into a predetermined shape. In a preferred embodiment, even if it is thermoformed, wrinkles or the like do not occur. Therefore, the laminate of the present invention has excellent appearance. The molding method is preferably melt molding, and the melt molding method is not particularly limited, but examples thereof include extrusion molding, injection molding, extrusion film formation from a T-die, inflation film formation, compression molding, transfer molding, reinforced plastic molding, hollow molding, press molding, blow molding, calendar molding, foam molding, vacuum molding, and pressure molding. If desired, other thermoplastic resins can be laminated by methods such as co-extrusion molding and laminate molding. These methods can provide molded bodies of any shape, such as films, sheets, tubes, bottles, capsules, nonwoven fabrics, and fibers. In one embodiment of the present invention, when molding by vacuum molding, the laminate can be heated and then molded into a desired shape by a vacuum molding machine. The molding temperature is not limited and can be appropriately selected depending on the type of laminate, and is preferably 100° C. or higher, more preferably 130° C. or higher, and even more preferably 150° C. or higher, and is preferably 300° C. or lower, and more preferably 200° C. or lower. When the molding temperature is in this range, a molded product having excellent thermoformability is easily formed.

[0085] [Food packaging materials] The adhesive resin composition and laminate of the present invention are not particularly limited in use, but can be suitably used as a packaging material, particularly as a food packaging material. Therefore, the present invention includes a food packaging material, particularly a coffee capsule, that includes an adhesive layer containing the adhesive resin composition of the present invention or a laminate of the present invention. The food packaging material of the present invention is excellent in adhesive strength, heat resistance, thermoformability, biodegradability, and gas barrier properties because it includes the adhesive layer or laminate of the present invention. The food packaging material is not particularly limited, but examples thereof include containers for packaging foods such as meat, raw noodles, processed foods, black tea, coffee powder, coffee beans, and pickles. In a preferred embodiment of the present invention, the food packaging material may be a rubber bag for organic waste, a container used in various events, a black tea bag, a coffee capsule, or the like, and is particularly suitably used as a coffee capsule. EXAMPLES

[0086] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples in any way. The measurement methods and evaluation methods used in the following examples and comparative examples are shown below.

[0087] [Elongation at break] The sheet obtained by hot press molding the biodegradable polyester resin was cut into a piece having a width of 15 mm and a length of 100 mm, and the breaking elongation was measured in accordance with ISO527-1.

[0088] [Melting point] Of the resin composition pellets obtained in each Example and Comparative Example, 10 mg was sealed in an aluminum pan (manufactured by TA Instruments), heated from -30°C to 220°C at a rate of 10°C / min, then rapidly cooled to -30°C at a rate of 10°C / min, and heated again from -30°C to 220°C at a rate of 10°C / min to perform DSC measurement. The melting point Tm (°C) was determined from the apex temperature of the peak in the temperature range from the start to the end of melting during the second heating in the obtained DSC curve.

[0089] [MFR] For the biodegradable polyester resin (A), the MFR was measured at 200 °C under a load of 2.16 kg in accordance with JIS K7210:2014.

[0090] [Mw, Mn] The Mw and Mn of the biodegradable polyester resin (A) were measured using the relative molecular weight analysis method by GPC analysis shown below. <Sample preparation> Approximately 5 mg of the powder sample of the biodegradable polyester resin (A) was collected and precisely weighed. To the collected sample, hexafluoroisopropanol (HFIP) added with 1 ml of 20 mM sodium trifluoroacetate per 1 mg of the sample was added, and the mixture was heated at 40 °C for 3 hours to dissolve. Using this solution, GPC analysis was performed under the following conditions. The calculation of the relative molecular weight distribution curve was performed by converting the relative molecular weight obtained from the RI detector using the analysis software attached to the analyzer. The analysis was performed 3 times for the same sample, and the average value was taken as the analysis result.

[0091] <GPC analysis conditions> Measuring device: HLC-8320GPC (manufactured by TOSOH Corporation) Analysis software: Empower (manufactured by Waters Corporation) Sample concentration: 0.1 mg / ml Mobile phase solvent: Hexafluoroisopropanol added with 20 mM Na trifluoroacetate Injection volume: 10 μl Flow rate: 0.2 ml / min Measurement temperature: 40 °C Sample dissolution conditions: 40 °C × 3 hours Filter filtration: 0.45 μm PTFE filter Column: 2 pieces of GMMHR-H(S) (manufactured by TOSOH Corporation) Detector: RI detector attached to the device Standard sample for device calibration: PMMA (manufactured by Agilent Corporation)

[0092] [Thickness] The thickness of the sheet made of the adhesive resin composition, the laminate, and each layer in the laminate in the examples and comparative examples were measured with a digital micrometer.

[0093] [Glass transition temperature (Tg)] The Tg of the polyol (B) was evaluated by DSC measurement under nitrogen at a heating rate of 10° C. / min.

[0094] [Adhesive strength of adhesive resin composition to PVA-based resin layer] The adhesive resin composition pellets obtained in the examples and comparative examples were preheated at 180°C for 5 minutes using a compression molding machine, and then subjected to a load of 50 kgf / cm 2 The adhesive resin composition was compressed and molded for 30 seconds under the conditions described above to obtain a film (also referred to as an adhesive layer) made of the adhesive resin composition. A film made of the adhesive resin composition (length 150 mm × width 150 mm × thickness 0.3 mm), a polyimide film ("Kapton film" manufactured by Toray DuPont Co., Ltd., length 75 mm × width 150 mm × thickness 0.05 mm), and a film made of polyvinyl alcohol resin (also referred to as a PVA resin layer) ("Mobiflex C17" manufactured by Kuraray Co., Ltd., length 150 mm × width 150 mm × thickness 0.5 mm) were stacked in this order and placed at the center of a metal spacer with inner dimensions of 150 mm × 150 mm and a thickness of 0.8 mm. The stacked films and metal spacer were sandwiched between polytetrafluoroethylene sheets and further sandwiched between metal plates from the outside, and compressed at 180°C under a load of 50 kgf / cm using a compression molding machine. 2 The mixture was compressed at RT for 30 seconds to obtain a multilayer sheet including an adhesive layer and a PVA resin layer. The multilayer sheet was cut to a width of 25 mm to prepare test pieces for measuring adhesive strength, and the peel strength between the adhesive layer and the PVA resin layer was measured in accordance with JIS K 6854-2 using a peel tester (Shimadzu Corporation's "AGS-X") under conditions of a peel angle of 180°, a tensile speed of 100 mm / min, and an ambient temperature of 23°C, and this was regarded as the adhesive strength of the adhesive resin composition to the PVA resin layer.

[0095] [Adhesive strength of adhesive resin composition to PLA (polylactic acid) resin layer] The adhesive resin composition pellets obtained in the examples and comparative examples were subjected to a heat press at 150° C. and a load of 100 kgf / cm using a heat press machine ("Automatic Press SF-37" manufactured by Shinto Metal Industries Co., Ltd.). 2 The adhesive resin composition was compressed for 30 seconds under the conditions to obtain a film (also called an adhesive layer) made of the adhesive resin composition. A film made of the adhesive resin composition (length 150 mm x width 150 mm x thickness 0.5 mm), a polyimide film (UBE Corporation's "Upilex", length 75 mm x width 150 mm x thickness 0.05 mm), and a film made of PLA resin (also called a PLA resin layer) (Nature Works' "Ingeo 2003D", length 150 mm x width 150 mm x thickness 0.3 mm) were stacked in this order and placed at the center of a metal spacer with inner dimensions of 150 mm x 150 mm and a thickness of 0.8 mm. The stacked films and metal spacer were sandwiched between polytetrafluoroethylene sheets and further sandwiched between metal plates from the outside, and pressed at 180°C and a load of 50 kgf / cm using a heat press. 2 The mixture was compressed at 400° C. for 30 seconds to obtain a multilayer sheet including an adhesive layer and a PLA resin layer. The multilayer sheet was cut into a width of 25 mm to prepare test pieces for measuring adhesive strength, and the peel strength between the adhesive layer and the PLA resin layer was measured in accordance with JIS K 6854-2 using a peel tester (Shimadzu Corporation's "AGS-X") under conditions of a peel angle of 180°, a tensile speed of 100 mm / min, and an ambient temperature of 23°C, and this was regarded as the adhesive strength of the adhesive resin composition to the PLA resin layer.

[0096] The adhesive strength was evaluated according to the following criteria, and the results are shown in Table 2. ◎: Peel strength is 25N / 25mm or more ○: Peel strength is 5N / 25mm or more and less than 25N / 25mm ×: Peel strength is less than 5N / 25mm

[0097] [Heat resistance evaluation] A circular capillary (diameter: 1 mm) was attached to a capillary rheometer (CAPIROGRAPH 1C, manufactured by TOYOSEIKI CORPORATION), and the adhesive resin compositions obtained in the Examples and Comparative Examples were retained at a temperature of 200°C for 5 minutes, and then extruded at a piston speed of 10 mm / min. The coloring of the resulting strands was visually observed, and the heat resistance was evaluated using the following indices. The results are shown in Table 2. ◎: No coloring ○: Light brown coloring ×: Brown to black coloring

[0098] [Example 1] <Adhesive resin composition> As the biodegradable polyester (A), 100 parts by mass of polybutylene adipate terephthalate (BASF's "Ecoflex FBlend C1200", melting point: 118°C, elongation at break: 1102%, MFR: 15.8 g / 10 min, Mw: 72000, Mn: 24500), as the polyol (B), 10.0 parts by mass of maltitol (Itochu Sugar Co., Ltd.'s "Parisienne", Tg: 47°C), and 15.0 parts by mass of modified starch (C) (Ingredion's "Capsul (registered trademark)", corn starch modified with octenylsuccinic anhydride, weight average molecular weight 32,000, average amylose content 1% by mass) was dry blended and then melt-kneaded under the following conditions using a twin-screw extruder KZW15-45MG (D=15 mmφ, L / D=45, Technobel Corp.). The molten mixture was extruded from a strand nozzle, and the resulting strand was cooled and cut to obtain pellets of the adhesive resin composition. [Table 1] Screw rotation speed: 250 rpm Operation method: Same direction, same rotation, fully meshed type

[0099] <Laminate> A three-kind, five-layer laminate in which a biodegradable resin layer / adhesive layer / polyvinyl alcohol-based resin layer / adhesive layer / biodegradable resin layer were laminated in this order was produced by the following method. The pellets of the adhesive resin composition obtained above, the pellets of the polyvinyl alcohol resin composition (a composition obtained by kneading 100 parts by mass of ethylene-vinyl alcohol copolymer (A1) / 67 parts by mass of trehalose with a twin-screw extruder), and the pellets of polylactic acid (Natureworks, Ingeo (registered trademark), biopolymer 2003D) were each put into the hopper of a single-screw extruder (GM ENGINEERING, VGM25-28EX), and co-extruded at a flow rate of 5 kg / h using a feed block die to obtain a 20 cm wide three-type five-layer laminate. At this time, the cylinder temperatures set were as follows. (Cylinder temperature) Adhesive layer: 180°C, polyvinyl alcohol resin layer: 210°C, biodegradable resin layer: 220°C

[0100] The resulting laminate had a structure of polylactic acid layer / adhesive layer / polyvinyl alcohol-based resin layer / adhesive layer / polylactic acid layer=250 μm / 20 μm / 30 μm / 20 μm / 250 μm (thickness) from the outside.

[0101] [Examples 2 to 11 and Comparative Examples 1 to 5] An adhesive resin composition and a laminate were obtained in the same manner as in Example 1, except that the types and amounts of the biodegradable polyester resin (A), polyol (B) and modified starch (C) used in preparing the adhesive resin composition were changed as shown in Table 2. In Table 2, the PBAT and maltitol used were the same as those used in Example 1, the sorbitol was "D(-)-sorbitol" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Tg: -4°C, the trehalose was "Treha" manufactured by Hayashibara Co., Ltd., Tg: 120°C, and the glycerin was "Glycerin" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Tg: -75°C. The PBAT used in the examples and comparative examples satisfies the biodegradability standards specified in EN13432 and ASTM6400.

[0102] According to the above method, the peel strength of each adhesive resin composition obtained in the examples and comparative examples was measured for the PLA resin layer and the PVA resin layer, and the adhesive strength was evaluated. In addition, the heat resistance of each adhesive resin composition was evaluated. The results are shown in Table 2. In Table 2, "cohesive failure" indicates that the film (adhesive layer) made of the adhesive resin composition broke before peeling in the peel test. The adhesive strength of the film (adhesive layer) that had cohesive failure was evaluated based on the strength at the time of cohesive failure. The value in parentheses indicates the strength at the time of cohesive failure, and *1 indicates that the material was so fragile that the strength at the time of cohesive failure could not be measured. [Table 2]

[0103] As shown in Table 2, the adhesive resin compositions of Examples 1 to 11 were confirmed to have high evaluations of adhesive strength to both the PVA-based resin layer and the PLA resin layer, and high evaluations of heat resistance. In contrast, the adhesive resin compositions of Comparative Examples 1 to 5 were confirmed to have poor evaluations in at least one of the categories. Therefore, the adhesive resin composition of the present invention is excellent in heat resistance and adhesive strength to both the PVA-based resin layer and the biodegradable resin layer.

Claims

1. Based on 100 parts by mass of the biodegradable polyester resin (A), it contains 3 to 24 parts by mass of polyol (B) and 0 to 40 parts by mass of starch or modified starch (C), and the total amount of polyol (B) and starch or modified starch (C) is 44 parts by mass or less. The biodegradable polyester (A) has an elongation at break of 50% or more measured in accordance with ISO 527-1, and the glass transition temperature of the polyol (B) is -10°C or higher. An adhesive resin composition.

2. The melting point of the biodegradable polyester resin (A) is 70°C or higher. The adhesive resin composition according to Claim 1.

3. The biodegradable polyester resin (A) includes an aromatic-aliphatic copolyester resin. The adhesive resin composition according to Claim 1.

4. The aromatic-aliphatic copolyester resin is polybutylene adipate terephthalate. The adhesive resin composition according to Claim 3.

5. The polyol (B) is at least one selected from the group consisting of maltitol, sorbitol, and trehalose. The adhesive resin composition according to Claim 1.

6. The adhesive resin composition according to Claim 1, which does not contain starch or modified starch (C).

7. A laminate including an adhesive layer comprising the adhesive resin composition according to any one of Claims 1 to 6.

8. The laminate according to Claim 7, comprising a biodegradable resin layer, the adhesive layer, and a polyvinyl alcohol-based resin layer in this order.

9. A food packaging material including an adhesive layer comprising the adhesive resin composition according to any one of Claims 1 to 6.

10. A coffee capsule including an adhesive layer comprising the adhesive resin composition according to any one of Claims 1 to 6.