Biodegradable laminate, method for producing same, and packaging material

Abstract

This biodegradable laminate has a first layer, a second layer that is an adhesive layer, and a third layer that contains a polyvinyl alcohol-based resin in this order. The first layer contains an aliphatic polyester resin (a). The aliphatic polyester resin (a) has, as main constituent units, a first repeating constituent unit that is derived from an aliphatic diol and a second repeating constituent unit that is derived from an aliphatic dicarboxylic acid. The second repeating constituent unit contains at least a repeating constituent unit that is derived from succinic acid and a repeating constituent unit that is derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms.

Description

Biodegradable laminate, its manufacturing method, and packaging material

[0001] The present invention relates to a biodegradable laminate, a method for producing the same, and a packaging material or the like having the biodegradable laminate.

[0002] In recent years, concerns about ecosystem and environmental pollution due to the disposal of plastic products in the ocean and other areas have become apparent. Various regulations are being enacted around the world, with a view to preventing environmental pollution and other factors. For example, Europe is currently enacting regulations and laws banning the use of disposable plastic shopping bags and disposable plastic containers such as cups and plates in retail. To be exempt from the legal ban, products must be made from biomass with a minimum biomass content specified and be compostable in ordinary households (home compostable products, hereafter also referred to as "HC"). Recently, there has also been a demand for marine biodegradable plastic products, which decompose in the ocean if they are released into the ocean.

[0003] Patent Document 1 discloses an invention related to a biodegradable laminate. The invention of Patent Document 1 aims to provide a biodegradable laminate that has a fast biodegradation rate at room temperature, excellent moldability when obtaining a biodegradable laminate, properties such as impact resistance and heat resistance, and both water vapor barrier property and oxygen barrier property when made into a sheet or container. Patent Document 1 discloses that this objective is achieved by a biodegradable laminate comprising an aliphatic polyester-based resin layer and a polyvinyl alcohol-based resin layer laminated via an adhesive layer on at least one surface of the aliphatic polyester-based resin layer, the aliphatic polyester-based resin layer comprising an aliphatic polyester-based resin composition containing an aliphatic polyester resin (A) containing, as main structural units, a repeating unit derived from an aliphatic diol and a repeating unit derived from an aliphatic dicarboxylic acid, a 3-hydroxyalkanoate (B), and an inorganic filler (C).

[0004] International Publication No. 2019 / 189745 Japanese Patent Application Laid-Open No. 2006-95825

[0005] In recent years, the social trend toward stronger environmental protection has led to a demand for biodegradable resins that are completely biodegradable, rather than only partially biodegradable. Furthermore, the biodegradation environment requires not only biodegradability in an aerobic compost environment at relatively high temperatures (58°C or higher) but also biodegradability in an aerobic compost environment at room temperature (28°C). According to the inventors' studies, the biodegradable laminate disclosed in Patent Document 1 satisfies these requirements well. However, in the course of further investigation into the biodegradable laminate disclosed in Patent Document 1, the inventors have discovered a new problem to be solved. Specifically, the biodegradable laminate disclosed in Patent Document 1 is produced, for example, by multilayer coextrusion molding. The inventors discovered that there is still room for improvement in the releasability of the laminate from a cooling member such as a cooling roll when the laminate, extruded from a T-die and at least partially in a molten or semi-molten state, comes into contact with the cooling member (hereinafter also referred to as "releasing ability from the roll"). Poor roll release properties can result in poor appearance of the resulting laminate, or the molding of the laminate itself can be difficult. At least one aspect of the present invention is directed to providing a biodegradable laminate that has excellent biodegradability, preferably complete biodegradability in a home composting environment, and an excellent appearance, and a method for producing the biodegradable laminate. Also, at least one aspect of the present invention is directed to providing a packaging material or the like that has complete biodegradability in a home composting environment and an excellent appearance.

[0006] The gist of the present invention is the following [1] to

[23] . [1] A biodegradable laminate comprising, in this order, a first layer containing an aliphatic polyester resin, a second layer serving as an adhesive layer, and a third layer containing a polyvinyl alcohol resin, wherein the first layer contains an aliphatic polyester resin (a), and the aliphatic polyester resin (a) has, as main structural units, a first repeating structural unit derived from an aliphatic diol and a second repeating structural unit derived from an aliphatic dicarboxylic acid, and the second repeating structural unit contains at least a repeating structural unit derived from succinic acid and a repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms. [2] The biodegradable laminate according to claim 1, wherein the content of the aliphatic polyester resin (a) in the first layer is 1% by mass or more and 100% by mass or less. [3] The biodegradable laminate according to claim 1, wherein the content of the aliphatic polyester resin (a) in the first layer is greater than 42% by mass and less than 100% by mass. [4] The laminate according to claim 1, wherein the content of the aliphatic polyester resin (a) in the first layer is greater than 42% by mass and less than 100% by mass. [5] The biodegradable laminate according to [1] above, wherein the content of the repeating structural units derived from succinic acid is greater than 50 mol% and less than 99 mol%, based on the total number of moles of the second repeating structural units. [6] The biodegradable laminate according to any of [1] to [5] above, wherein the content of the repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms is greater than 1 mol% and less than 50 mol%, based on the total number of moles of the second repeating structural units. [7] The biodegradable laminate according to any one of [1] to [6] above, wherein the content of the repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms is greater than 3 mol% and not more than 40 mol%, based on the total number of moles of the second repeating structural units. [8] The biodegradable laminate according to any one of [1] to [7] above, wherein the content of the repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms is greater than 5 mol% and not more than 35 mol%, based on the total number of moles of the second repeating structural units.[9] The biodegradable laminate according to any one of [1] to [8] above, wherein the content of the repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms is 7 mol% or more and 35 mol% or less, based on the total number of moles of the second repeating structural units.

[10] The biodegradable laminate according to any one of [1] to [9] above, wherein the content of the repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms relative to the repeating structural units derived from an aliphatic dicarboxylic acid in the aliphatic polyester resin (a) is 10 mol% or more and 30 mol% or less.

[11] The biodegradable laminate according to any one of [1] to

[10] above, wherein the content of the repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms relative to the repeating structural units derived from an aliphatic dicarboxylic acid in the aliphatic polyester resin (a) is 11 mol% or more and 30 mol% or less.

[12] The biodegradable laminate according to any one of [1] to

[11] above, wherein the aliphatic polyester resin (a) contains, as the repeating structural unit derived from the aliphatic dicarboxylic acid, a repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 13 carbon atoms.

[13] The biodegradable laminate according to any one of [1] to

[12] above, wherein the aliphatic dicarboxylic acid having 9 to 36 carbon atoms is sebacic acid.

[14] The biodegradable laminate according to any one of [1] to

[13] above, wherein the first layer further contains a biodegradable polyester-based resin (d) different from the aliphatic polyester resin (a).

[15] The biodegradable laminate according to

[14] above, wherein the biodegradable polyester-based resin (d) has, as main structural units, a third repeating structural unit derived from an aliphatic diol and a fourth repeating structural unit derived from an aliphatic dicarboxylic acid, and the fourth repeating structural unit contains a repeating structural unit derived from succinic acid.

[16] The biodegradable laminate according to the above

[14] , wherein the biodegradable polyester resin (d) contains a polyhydroxyalkanoate containing a 3-hydroxybutyrate unit as a main structural unit.

[17] The biodegradable laminate according to any one of the above

[14] to

[16] , wherein the mass ratio of the biodegradable polyester resin (d) to the aliphatic polyester resin (a) in the first layer is 0 mass% or more and 40 mass% or less.

[18] The biodegradable laminate according to any one of [1] to

[17] above, wherein the first layer further contains an inorganic filler (e).

[19] The biodegradable laminate according to any one of

[11] to

[18] above, wherein the first layer contains an inorganic filler (e), and the mass ratio of the inorganic filler (e) in the first layer to the total amount of the aliphatic polyester resin (a) and the aliphatic polyester-based resin (d) is 0 mass% or more and 50 mass% or less.

[20] The biodegradable laminate according to any one of [1] to

[19] above, wherein the second layer contains a modified polyester-based resin (F) obtained by graft-modifying a polyester-based resin with an α,β-unsaturated carboxylic acid and / or an anhydride thereof, and the polyester-based resin mainly contains at least one selected from the group consisting of an aliphatic polyester and an aliphatic-aromatic polyester-based resin.

[21] A packaging material comprising the biodegradable laminate according to any one of [1] to

[20] above.

[22] A coffee capsule, a food container, or a food packaging film, comprising the biodegradable laminate according to any one of [1] to

[20] above.

[23] A method for producing the biodegradable laminate according to any one of [1] to

[22] above, comprising the step of contacting the first layer of a melt co-extrusion molded product having the first layer, the second layer, and the third layer in this order with a cooling member.

[0007] According to at least one aspect of the present invention, a biodegradable laminate having excellent biodegradability, particularly complete biodegradability in a home composting environment, and an excellent appearance can be obtained. Also, according to at least one aspect of the present invention, a packaging material or the like having excellent appearance and complete biodegradability in a home composting environment can be obtained.

[0008] 1 is a schematic cross-sectional view of a biodegradable laminate according to one embodiment of the present invention; 2 is a schematic cross-sectional view of a biodegradable laminate according to another embodiment of the present invention; 3 is an explanatory diagram of a manufacturing apparatus for a biodegradable laminate according to one embodiment of the present invention;

[0009] In the present invention, descriptions such as "XX or more and YY or less" and "XX to YY" that represent a numerical range mean a numerical range that includes the endpoints XX and YY, unless otherwise specified. Furthermore, when a numerical range is described in stages, any combination of the upper and lower limits of each numerical range is also disclosed. Furthermore, in the present invention, for example, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

[0010] The present inventors believe that one of the reasons why the biodegradable laminate disclosed in Patent Document 1 may stick to a chill roll during its production, resulting in poor appearance, is due to the strong interaction of the aliphatic polyester resin (A) contained in the aliphatic polyester resin layer (A) constituting the outermost layer of the biodegradable laminate with the surface (metal surface) of the chill roll. Specifically, they speculate that sticking to the chill roll occurs due to the strong interaction of the molten aliphatic polyester resin with the contact surface when it comes into contact with the chill roll. Therefore, in order to prevent sticking to the chill roll, the present inventors investigated the composition of a biodegradable aliphatic polyester resin that reduces the interaction with the chill roll surface when it comes into contact with the chill roll in a molten state. As a result, they found that by including both a repeating structural unit derived from succinic acid and a repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms as repeating structural units derived from aliphatic dicarboxylic acids in the aliphatic polyester resin, the interaction of the aliphatic polyester resin with the chill roll surface can be weakened, and as a result, sticking to the chill roll can be prevented.

[0011] That is, a biodegradable laminate according to one embodiment of the present invention has a first layer, a second layer, and a third layer containing a polyvinyl alcohol-based resin, in this order. As used herein, "having a first layer, a second layer, and a third layer in this order" means that the layers are arranged in this order, and other layers may be interposed between the layers. The first layer contains an aliphatic polyester resin (a), which has, as main structural units, a first repeating structural unit derived from an aliphatic diol and a second repeating structural unit derived from an aliphatic dicarboxylic acid. The second repeating structural unit contains at least a repeating structural unit derived from succinic acid and a repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms.

[0012] In the aliphatic polyester resin (a), the "first repeating structural unit derived from an aliphatic diol" refers to a "repeating structural unit corresponding to an aliphatic diol," i.e., a structural unit formed by the reaction of two hydroxyl groups possessed by an aliphatic diol. The "second repeating structural unit derived from an aliphatic dicarboxylic acid" refers to a "repeating structural unit corresponding to an aliphatic dicarboxylic acid," i.e., a repeating structural unit formed by the reaction of two carboxy groups possessed by an aliphatic dicarboxylic acid. Furthermore, the "repeating structural unit derived from succinic acid" refers to a "structural unit corresponding to succinic acid," i.e., a structural unit formed by the reaction of two carboxy groups possessed by succinic acid. Furthermore, the "repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms" refers to a "structural unit corresponding to an aliphatic dicarboxylic acid having 9 to 36 carbon atoms," i.e., a structural unit formed by the reaction of two carboxy groups possessed by an aliphatic dicarboxylic acid having 9 to 36 carbon atoms.

[0013] The first, second, and third layers, which are basic structural units of a biodegradable laminate according to one embodiment of the present invention, are described in detail below. [First Layer] The first layer contains at least an aliphatic polyester resin (a). The first layer may also contain any other components within the scope of the present invention. Specifically, for example, the first layer may contain, as optional components, a biodegradable polyester resin (d) different from the aliphatic polyester resin (a) and / or an inorganic filler (e). The aliphatic polyester resin (a) contained in the first layer and the optional components that may be contained in the first layer are described in detail below. <Aliphatic Polyester Resin (a)> The aliphatic polyester resin (a) has, as its main structural units, a first repeating structural unit derived from an aliphatic diol and a second repeating structural unit derived from an aliphatic dicarboxylic acid. The second repeating structural unit contains at least a repeating structural unit derived from succinic acid and a repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms.

[0014] In this specification, the term "aliphatic diol" refers to a compound having two hydroxyl groups bonded to an aliphatic hydrocarbon group. The aliphatic hydrocarbon group is usually a straight-chain aliphatic hydrocarbon group, but may have a branched structure, a cyclic structure, or multiple branched and / or cyclic structures. In this specification, the term "aliphatic dicarboxylic acid" refers to a compound having two carboxy groups bonded to an aliphatic hydrocarbon group. The aliphatic hydrocarbon group is usually a straight-chain aliphatic hydrocarbon group, but may have a branched structure, a cyclic structure, or multiple branched and / or cyclic structures. In this specification, the term "main structural unit" refers to a structural unit that is contained in the aliphatic polyester resin (a) at a ratio of 80 mol% or more, and may be 90 mol% or more. It may also be 100 mol% when no structural units other than the main structural unit are contained.

[0015] Furthermore, in this specification, the aliphatic polyester resin (a) is a polymer having repeating structural units, and each repeating structural unit may be referred to as a compound unit corresponding to the compound from which the repeating structural unit is derived. Specifically, for example, a repeating structural unit derived from an aliphatic diol is referred to as an "aliphatic diol unit (or diol unit)," and a repeating structural unit derived from an aliphatic dicarboxylic acid is referred to as an "aliphatic dicarboxylic acid unit (or dicarboxylic acid unit)."

[0016] The term "first repeating structural unit derived from an aliphatic diol" refers to a "repeating structural unit corresponding to an aliphatic diol," i.e., a structural unit formed by the reaction of two hydroxyl groups possessed by an aliphatic diol. The term "second repeating structural unit derived from an aliphatic dicarboxylic acid" refers to a "repeating structural unit corresponding to an aliphatic dicarboxylic acid," i.e., a repeating structural unit formed by the reaction of two carboxy groups possessed by an aliphatic dicarboxylic acid. The term "repeating structural unit derived from succinic acid" refers to a "structural unit corresponding to succinic acid," i.e., a structural unit formed by the reaction of two carboxy groups possessed by succinic acid. The term "repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms" refers to a "structural unit corresponding to an aliphatic dicarboxylic acid having 9 to 36 carbon atoms," i.e., a structural unit formed by the reaction of two carboxy groups possessed by an aliphatic dicarboxylic acid having 9 to 36 carbon atoms.

[0017] The aliphatic polyester resin (a) has, as its main structural units, an aliphatic diol unit as a first structural unit and an aliphatic dicarboxylic acid unit as a second repeating structural unit. The aliphatic dicarboxylic acid unit includes a repeating structural unit derived from succinic acid (hereinafter also referred to as a "succinic acid unit") and a repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms (hereinafter also referred to as an "aliphatic dicarboxylic acid unit having 9 to 36 carbon atoms").

[0018] Specifically, for example, the aliphatic polyester resin (a) according to one embodiment of the present invention has, as main repeating structural units, a first repeating structural unit and a second repeating structural unit, and the first repeating structural unit has an aliphatic diol unit represented by the following formula (1), and the second repeating structural unit has a succinic acid unit represented by the following formula (2) and an aliphatic dicarboxylic acid unit having 9 to 36 carbon atoms represented by the following formula (3). The aliphatic polyester resin (a) may also have structural units other than these structural units. -O-R １ -O- (1) -OC-CH ２ -CH ２ -CO- (2) -OC-R ２ -CO- (3)

[0019] In formula (1), R １ represents a divalent aliphatic hydrocarbon group which may have a substituent. １ As described above, may be linear or branched, or may have a ring structure.

[0020] In addition, in formula (3), R ２ represents a divalent aliphatic hydrocarbon group having 7 to 34 carbon atoms (i.e., an aliphatic dicarboxylic acid unit having 9 to 36 carbon atoms) which may have a substituent, and preferably represents a divalent aliphatic hydrocarbon group having 7 to 11 carbon atoms (i.e., an aliphatic dicarboxylic acid unit having 9 to 13 carbon atoms) which may have a substituent. ２ As described above, R may be linear or branched, or may have a ring structure. In particular, from the viewpoint of excellent biodegradability of the polyester resin composition, particularly excellent home compostability, and improved release from the roll due to an accelerated solidification rate during molding, R ２is preferably an aliphatic hydrocarbon group having 7 to 34 carbon atoms, preferably 7 to 11 carbon atoms. By introducing an aliphatic dicarboxylic acid unit having an aliphatic hydrocarbon group of appropriate length having 9 to 36 carbon atoms, particularly 9 to 13 carbon atoms, into the second repeating structural unit, the crystallinity of the aliphatic polyester resin (a) is appropriately reduced, resulting in excellent biodegradability, particularly complete biodegradability even in a HC environment. Furthermore, the presence of an aliphatic hydrocarbon group of appropriate length in the aliphatic polyester (a) reduces the polarity of the aliphatic polyester (a) and reduces the interaction between the aliphatic polyester resin (a) and metals. This makes it easier for the resin composition containing the aliphatic polyester resin (a) to be peeled from a cooling roll during molding, improving roll-release properties. As a result, it is believed that a biodegradable laminate with good appearance can be obtained.

[0021] The aliphatic diol units, succinic acid units, and aliphatic dicarboxylic acid units having 9 to 36 carbon atoms represented by the above formulas (1), (2), and (3) may be derived from compounds derived from petroleum or from compounds derived from plant raw materials, but are preferably derived from compounds derived from plant raw materials.

[0022] R １ and R ２ The types of substituents (including atoms) that R may have are not particularly limited as long as the effects of the present invention can be obtained. １ and R ２ Examples of the substituents that R may have are, independently of each other, at least one atom or group selected from the group consisting of a halogen atom, a cyano group, an amino group, an ester group, an alkylcarbonyl group, an acetyl group, a silyl group, a boryl group, a nitrile group, a thiol group, and a seleno group. １ and R ２ The hydrocarbon group in may not have a substituent.

[0023] The first repeating structural unit may contain two or more types selected from the group consisting of aliphatic diol units represented by the above formula (1), and the second repeating structural unit may contain two or more types of aliphatic dicarboxylic acid units represented by the above formula (3).

[0024] The aliphatic diol that provides the diol unit represented by formula (1) is not particularly limited, but from the viewpoint of the moldability of the polyester resin composition and the mechanical strength of the molded product, an aliphatic diol having 2 to 10 carbon atoms is preferred, and an aliphatic diol having 4 to 6 carbon atoms is particularly preferred. １ As the aliphatic diol having a linear structure, a branched structure, or a cyclic structure, for example, at least one aliphatic diol selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, etc., can be suitably used. Among these, 1,4-butanediol is particularly preferred.

[0025] The aliphatic dicarboxylic acid that provides the aliphatic dicarboxylic acid unit represented by formula (3) is not particularly limited as long as it is an aliphatic dicarboxylic acid having 9 to 36 carbon atoms, but from the viewpoint of heat resistance, an aliphatic dicarboxylic acid having 9 to 13 carbon atoms is preferred. Examples of aliphatic dicarboxylic acids having 9 to 36 carbon atoms include azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and brassylic acid. Among these, azelaic acid and sebacic acid are particularly preferred, and sebacic acid is particularly preferred.

[0026] The content of the aliphatic diol unit (first repeating structural unit) in the aliphatic polyester resin (a) is not particularly limited, but from the viewpoint of biodegradability, it is usually 25 mol% or more, preferably 30 mol% or more, more preferably 35 mol% or more, even more preferably 40 mol% or more, particularly preferably 45 mol% or more, and most preferably 47 mol% or more, and is usually 75 mol% or less, preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 60 mol% or less, particularly preferably 55 mol% or less, and most preferably 53 mol% or less, relative to the total number of moles of the repeating structural units constituting the aliphatic polyester resin (a). That is, the content of the first repeating structural unit in the aliphatic polyester resin (a) is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, even more preferably 35 to 65 mol%, particularly preferably 40 to 60 mol%, even more preferably 45 to 55 mol%, and especially preferably 47 mol% to 53 mol% relative to the total number of moles of the repeating structural units constituting the aliphatic polyester resin (a). In this specification, the number of moles of the repeating structural units of the aliphatic polyester resin (a) is counted as 1 mole of the smallest ester unit of the aliphatic polyester resin (a). Furthermore, the number of moles of the first repeating structural unit is also counted as 1 mole of the smallest ester unit.

[0027] The content of the aliphatic dicarboxylic acid unit (second repeating structural unit) in the aliphatic polyester resin (a) is not particularly limited, and from the viewpoint of biodegradability, it is usually 25 mol% or more, preferably 30 mol% or more, more preferably 35 mol% or more, even more preferably 40 mol% or more, particularly preferably 45 mol% or more, and most preferably 47 mol% or more, relative to the total number of moles of the repeating structural units constituting the aliphatic polyester resin (a), and is usually 75 mol% or less, preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 60 mol% or less, particularly preferably 55 mol% or less, and most preferably 53 mol% or less. That is, the content of the second repeating structural unit in the aliphatic polyester resin (a) is preferably 25 mol% or more and 75 mol% or less, more preferably 30 mol% or more and 70 mol% or less, even more preferably 35 mol% or more and 65 mol% or less, particularly preferably 40 mol% or more and 60 mol% or less, even more preferably 45 mol% or more and 55 mol% or less, and particularly preferably 47 mol% or more and 53 mol% or less, based on the total number of moles of the repeating structural units constituting the aliphatic polyester resin (a).

[0028] <Content of each dicarboxylic acid unit in the second repeating structural unit> (1) Content of succinic acid unit The content of succinic acid units in the aliphatic polyester resin (a) is not particularly limited, but from the viewpoint of moldability, it is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and preferably 99 mol% or less, more preferably 97 mol% or less, even more preferably 95 mol% or less, relative to the total number of moles of all repeating structural units derived from all aliphatic dicarboxylic acids in the aliphatic polyester resin (a) (second repeating structural units). From the viewpoint of biodegradation rate and surface smoothness, it is particularly preferably 91 mol% or less, and may even be 89 mol% or less. That is, the content of repeating structural units derived from succinic acid in the second repeating structural units is preferably 50 mol% or more and 99 mol% or less, particularly preferably 60 mol% or more and 97 mol% or less, more preferably 70 mol% or more and 91 mol% or less, and even more preferably 70 mol% or more and 89 mol% or less, based on the total number of moles of the second repeating structural units.

[0029] (2) Content of aliphatic dicarboxylic acid units having 9 to 36 carbon atoms The content of aliphatic dicarboxylic acid units having 9 to 36 carbon atoms in the aliphatic polyester resin (a) is not particularly limited, but from the viewpoint of biodegradation rate and moldability, it is preferably 1 mol% or more, more preferably more than 3 mol%, even more preferably 5 mol% or more, particularly preferably 7 mol% or more, even more preferably 10 mol% or more, and even more particularly preferably 11 mol% or more, relative to the total number of moles of repeating structural units (second repeating structural units) derived from all aliphatic dicarboxylic acids in the aliphatic polyester resin (a). Also, it is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, and especially preferably 30 mol% or less. That is, the content of repeating structural units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms in the second repeating structural units is preferably 1 mol% or more and 50 mol% or less, particularly preferably more than 3 mol% and 40 mol% or less, even more preferably 5 mol% or more and 35 mol% or less, still more preferably 7 mol% or more and 35 mol% or less, particularly preferably 10 mol% or more and 30 mol% or less, and even more preferably 11 mol% or more and 30 mol% or less.

[0030] When the content of succinic acid units and aliphatic dicarboxylic acid units having 9 to 36 carbon atoms in the second repeating structural units satisfies the above ranges (1) and / or (2), the flowability (moldability) of the polyester-based resin composition according to the present invention is improved, and the polyester-based resin composition can give molded articles that are excellent in strength, appearance, easy biodegradability, heat resistance, etc.

[0031] (Other Copolymerization Components) Furthermore, for the purpose of improving heat resistance and strength, controlling biodegradability, etc., the aliphatic polyester resin (a) may have other aliphatic dicarboxylic acid units other than succinic acid units and aliphatic dicarboxylic acid units having 9 to 36 carbon atoms (hereinafter, may be referred to as "other aliphatic dicarboxylic acid units"). When the aliphatic polyester resin (a) contains other dicarboxylic acid units other than succinic acid units and aliphatic dicarboxylic acid units having 9 to 36 carbon atoms, the total content of the other structural units in the aliphatic polyester resin (a) is usually 0 mol% or more and 50 mol% or less, preferably 0 mol% or more and 30 mol% or less, and more preferably 0 mol% or more and 20 mol% or less, based on the total number of moles of all dicarboxylic acid units (succinic acid units, aliphatic dicarboxylic acid units having 9 to 36 carbon atoms, and other dicarboxylic acid units) in the aliphatic polyester resin (a).

[0032] Examples of the aliphatic dicarboxylic acid component acids that provide other aliphatic dicarboxylic acid units that can be contained in the aliphatic polyester resin (a) include oxalic acid, malonic acid, and adipic acid.

[0033] The aliphatic polyester resin (a) may have a repeating structural unit (aliphatic oxycarboxylic acid unit) derived from an aliphatic oxycarboxylic acid. Specific examples of the aliphatic oxycarboxylic acid component that provides the aliphatic oxycarboxylic acid unit include aliphatic oxycarboxylic acids such as lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, and 2-hydroxyisocaproic acid, as well as derivatives of these aliphatic oxycarboxylic acids, such as lower alkyl esters and intramolecular esters. When optical isomers exist, they may be in the D-form, L-form, or racemic form. Among these, lactic acid, glycolic acid, or derivatives thereof are particularly preferred. These aliphatic oxycarboxylic acids may be used alone or as a mixture of two or more. The aliphatic oxycarboxylic acid component used as a raw material may be in the form of a solid, liquid, or aqueous solution.

[0034] When the aliphatic polyester resin (a) contains these aliphatic oxycarboxylic acid units, the content thereof is, from the viewpoint of moldability, preferably 20 mol% or less, more preferably 10 mol% or less, even more preferably 5 mol% or less, and most preferably 0 mol% (not contained, i.e., below the detection limit) relative to the total number of moles of the repeating structural units constituting the aliphatic polyester resin (a).

[0035] Furthermore, the aliphatic polyester resin (a) may contain, as dicarboxylic acid units other than the aliphatic dicarboxylic acid units, aromatic dicarboxylic acid units such as terephthalic acid or isophthalic acid, as long as the effects of the present invention are not impaired.

[0036] The aliphatic polyester resin (a) may have an increased melt viscosity by copolymerizing a tri- or higher functional aliphatic polyhydric alcohol, a tri- or higher functional aliphatic polycarboxylic acid or an acid anhydride thereof, or a tri- or higher functional aliphatic polyoxycarboxylic acid component.

[0037] Specific examples of trifunctional aliphatic polyhydric alcohols include trimethylolpropane and glycerin, and specific examples of tetrafunctional aliphatic polyhydric alcohols include pentaerythritol. These may be used alone or in combination of two or more. Specific examples of trifunctional aliphatic polycarboxylic acids or acid anhydrides thereof include propanetricarboxylic acid or its acid anhydride, and specific examples of tetrafunctional polycarboxylic acids or its acid anhydrides include cyclopentanetetracarboxylic acid or its acid anhydride. These may be used alone or in combination of two or more.

[0038] Trifunctional aliphatic oxycarboxylic acid components are divided into (i) a type having two carboxy groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxy group and two hydroxyl groups in the same molecule, and either type can be used, but from the viewpoints of moldability, mechanical strength, and the appearance of molded products, (i) a type having two carboxy groups and one hydroxyl group in the same molecule, such as malic acid, is preferred, more specifically, malic acid is preferably used.Furthermore, tetrafunctional aliphatic oxycarboxylic acid components are divided into (i) a type having three carboxy groups and one hydroxyl group in the same molecule, (ii) a type having two carboxy groups and two hydroxyl groups in the same molecule, and (iii) a type having three hydroxy groups and one carboxy group in the same molecule, and either type can be used, but those having multiple carboxy groups are preferred, more specifically, citric acid, tartaric acid, etc. These may be used alone or in combination of two or more.

[0039] When the aliphatic polyester resin (a) contains such a structural unit derived from a trifunctional or higher functional component, the content thereof, relative to the total number of moles of the repeating structural units constituting the aliphatic polyester resin (a), has a lower limit of usually 0.00 mol % or more, preferably 0.01 mol % or more, and an upper limit of usually 4.00 mol % or less, preferably 2.50 mol % or less.

[0040] <Physical Properties of Aliphatic Polyester Resin (a)> (Melt Flow Rate (MFR)) The melt flow rate (MFR) of the aliphatic polyester resin (a) is a value measured at 190°C and 2.16 kgf in accordance with Japanese Industrial Standards (JIS) K 7210 (2014). From the viewpoints of moldability and mechanical strength, it is preferably 50.0 g / 10 min or less, more preferably 30.0 g / 10 min or less, preferably 0.1 g / 10 min or more, and more preferably 0.5 g / 10 min or more. That is, the MFR of the aliphatic polyester resin (a) measured under the above conditions is preferably 0.1 g / 10 min or more and 50.0 g / 10 min or less, particularly preferably 0.5 g / 10 min or more and 30.0 g / 10 min or less. The MFR of the aliphatic polyester resin (a) can be adjusted by the molecular weight.

[0041] (Melting Point) The melting point of the aliphatic polyester resin (a) is preferably 70°C or higher, more preferably 80°C or higher, and preferably 180°C or lower, more preferably 160°C or lower, particularly preferably lower than 140°C. When there are multiple melting points, it is preferable that at least one melting point is within the above range. The glass transition temperature and melting point of the aliphatic polyester resin (a) can be measured using a differential scanning calorimeter (for example, DSC8500 (manufactured by PerkinElmer Japan)). Specifically, about 5 mg of the aliphatic polyester resin (a) is precisely weighed, heated and melted under a nitrogen gas flow at a flow rate of 40 mL / min, cooled at a rate of 10°C / min, and then the glass transition temperature and melting point (peak top) can be measured while heating at a rate of 10°C / min.

[0042] (Weight-average molecular weight (Mw)) The molecular weight of the aliphatic polyester resin (a) can be measured by gel permeation chromatography (GPC). The weight-average molecular weight (Mw) of the aliphatic polyester resin (a) using monodisperse polystyrene as the standard is usually 10,000 or more and 1,000,000 or less. However, because this is advantageous in terms of moldability and mechanical strength, it is preferably 20,000 or more and 500,000 or less, more preferably 50,000 or more and 400,000 or less, and even more preferably 100,000 or more and 300,000 or less.

[0043] [Method for producing aliphatic polyester resin (a)] The method for producing the aliphatic polyester resin (a) according to this embodiment can employ a known method for producing polyesters. In addition, the polycondensation reaction at this time can be performed under suitable conditions that have been conventionally used, and is not particularly limited. Usually, a method is employed in which the degree of polymerization is further increased by carrying out a decompression operation after the esterification reaction has progressed.

[0044] When a diol component forming diol units (also referred to as "diol component providing diol units") and a dicarboxylic acid component forming dicarboxylic acid units (also referred to as "dicarboxylic acid providing dicarboxylic acid units") are reacted during the production of aliphatic polyester resin (a), the amounts of the diol component and the dicarboxylic acid component used are set so that the aliphatic polyester resin (a) produced has the desired composition. Usually, the diol component and the dicarboxylic acid component react in substantially equimolar amounts, but the diol component is usually used in a 1 to 50 mol % excess over the dicarboxylic acid component because it is distilled off during the esterification reaction.

[0045] When the aliphatic polyester resin (a) contains components (optional components) other than the essential components such as polyfunctional component units, the corresponding compounds (monomers or oligomers) are reacted so that the polyfunctional component units also have the desired composition. In this case, there are no limitations on the timing and method of introducing the optional components into the reaction system, and they are arbitrary as long as the aliphatic polyester resin (a) suitable for the present invention can be produced.

[0046] Aliphatic polyester resin (a) is usually produced in the presence of a catalyst. As the catalyst, any catalyst that can be used in the production of known polyester resins can be selected as long as it does not significantly impair the effects of the present invention. Examples of suitable catalysts include metal compounds such as germanium, titanium, zirconium, hafnium, antimony, tin, magnesium, calcium, and zinc. Among these, titanium compounds and germanium compounds are preferred.

[0047] Examples of titanium compounds that can be used as catalysts include organic titanium compounds such as tetraalkoxytitanium compounds such as tetrapropyl titanate, tetrabutyl titanate, and tetraphenyl titanate. Among these, tetrapropyl titanate and tetrabutyl titanate are preferred in terms of price and availability.

[0048] In addition, other catalysts may be used in combination as long as the object of the present invention is not impaired. The catalysts may be used alone or in any combination and ratio of two or more.

[0049] The amount of catalyst used is arbitrary as long as it does not significantly impair the effects of the present invention, but is usually 0.0005% by mass or more, more preferably 0.001% by mass or more, and usually 3% by mass or less, preferably 1.5% by mass or less, based on the amount of monomer used. If the amount is below the lower limit of this range, the effect of the catalyst may not be exhibited, while if the amount is above the upper limit, the production cost may increase, the resulting polymer may be significantly discolored, or the hydrolysis resistance may be reduced.

[0050] The timing of introducing the catalyst is not particularly limited as long as it is before the polycondensation reaction, and it may be introduced when the raw materials are charged or when the pressure reduction is started.

[0051] The reaction conditions, such as temperature, polymerization time, and pressure, used in producing the aliphatic polyester resin (a) may be any as long as they do not significantly impair the effects of the present invention. However, the reaction temperature for the esterification reaction and / or transesterification reaction between the dicarboxylic acid component and the diol component typically has a lower limit of 150°C or higher, preferably 180°C or higher, and an upper limit of 260°C or lower, preferably 250°C or lower. That is, the reaction temperature is preferably 150 to 260°C, and particularly preferably 180 to 250°C. The reaction atmosphere is typically an inert atmosphere such as nitrogen or argon. The reaction pressure is typically atmospheric pressure to 10 kPa, with atmospheric pressure being preferred. The reaction time typically has a lower limit of 1 hour or higher and an upper limit of 10 hours or less, preferably 6 hours or less, and more preferably 4 hours or less. By maintaining the reaction temperature within the above range, excessive generation of unsaturated bonds can be more reliably prevented, gelation caused by unsaturated bonds is suppressed, and polymerization control becomes easier.

[0052] The polycondensation reaction after the esterification reaction and / or transesterification reaction between the dicarboxylic acid component and the diol component is carried out under a pressure of usually 0.01×10 ３ Pa or more, preferably 0.03 × 10 ３ Pa or more, and the upper limit is usually 1.4 × 10 ３ Pa or less, preferably 0.4 × 10 ３ It is desirable to carry out the reaction under a vacuum of 100 Pa or less. The lower limit of the reaction temperature in the reaction is usually 150°C or higher, preferably 180°C or higher, and the upper limit is usually 260°C or lower, preferably 250°C or lower. That is, the reaction temperature in the polycondensation reaction is preferably 150 to 260°C, and particularly preferably 180 to 250°C. Furthermore, the lower limit of the reaction time is usually 2 hours or higher, and the upper limit is usually 15 hours or lower, preferably 10 hours or lower. By keeping the reaction temperature in the polycondensation reaction within the above range, excessive production of unsaturated bonds can be more reliably prevented, gelation caused by unsaturated bonds can be suppressed, and polymerization can be more easily controlled.

[0053] In the production of the aliphatic polyester resin (a), a chain extension reaction step using a chain extender may be performed after the polycondensation reaction step. The type of chain extender is not particularly limited, and for example, a carbonate compound or the like can be used. Specific examples of carbonate compounds as the chain extender include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, and dicyclohexyl carbonate. In addition, carbonate compounds composed of the same or different hydroxy compounds derived from hydroxy compounds such as phenols or alcohols can also be used.

[0054] The amount of chain extender is usually 10 mol% or less, preferably 5 mol% or less, more preferably 3 mol% or less, as the proportion of carbonate bonds in the polyester resin (a) when all the structural units constituting the aliphatic polyester resin (a) are 100 mol%, and in particular, in order to more reliably prevent the decrease in biodegradability due to the presence of carbonate bonds in the aliphatic polyester resin (a), it is preferably less than 1 mol%, more preferably 0.5 mol% or less, and even more preferably 0.1 mol% or less. These amounts, when converted to 100 parts by mass of the aliphatic polyester resin (a), are preferably 0.9 parts by mass or less, more preferably 0.5 parts by mass or less, even more preferably 0.2 parts by mass or less, and particularly preferably 0.1 parts by mass or less. The carbonate bond amount in the aliphatic polyester resin (a) is １ H-NMR and １３ The chain extender can be calculated from the results of NMR measurements such as C-NMR. From the perspective of expanding into a wide range of applications, such as food packaging, it is preferable not to use diisocyanate compounds as the chain extender. Furthermore, during film formation, decomposition of urethane bonds can cause smoke and odor from the molten film exiting the die, and foaming can cause film breakage in the molten film, hindering stable molding. Other chain extenders, such as dioxazoline or silicate esters, may also be used. Specific examples of silicate esters include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxysilane. Conventional techniques can also be applied to chain extension reactions using these chain extenders (coupling agents). For example, after polycondensation is completed, the chain extender is added to the reaction system in a homogeneous molten state without a solvent and allowed to react with the polyester obtained by polycondensation.

[0055] <Biodegradable Polyester Resin (d)> The biodegradable polyester resin (d) that the first layer may contain as an optional component is not particularly limited as long as it is different from the aliphatic polyester resin (a) and is biodegradable. Examples include biodegradable polyester resins having, as main structural units, a third repeating structural unit derived from an aliphatic diol and a fourth repeating structural unit derived from an aliphatic dicarboxylic acid, wherein the fourth repeating structural unit contains a repeating structural unit derived from succinic acid, and polyhydroxyalkanoates having, as the main structural unit, a structural unit derived from 3-hydroxybutyrate (hereinafter also referred to as a "3-hydroxybutyrate structural unit").

[0056] That is, the first layer has, as the optional biodegradable polyester resin (d), as main structural units, a third repeating structural unit derived from an aliphatic diol and a fourth repeating structural unit derived from an aliphatic dicarboxylic acid, and the fourth repeating structural unit can include at least one resin selected from the group consisting of biodegradable polyester resins containing a repeating structural unit derived from succinic acid and polyhydroxyalkanoates.

[0057] [Biodegradable polyester resin having, as main structural units, a third repeating structural unit derived from an aliphatic diol and a fourth repeating structural unit derived from an aliphatic dicarboxylic acid, wherein the fourth repeating structural unit comprises a repeating structural unit derived from succinic acid] As an example of the biodegradable polyester resin (d), in a biodegradable polyester resin having, as main structural units, a third repeating structural unit derived from an aliphatic diol and a fourth repeating structural unit derived from an aliphatic dicarboxylic acid, wherein the fourth repeating structural unit comprises a repeating structural unit derived from succinic acid, the fourth repeating structural unit may or may not comprise another aliphatic dicarboxylic acid unit. When the fourth repeating structural unit comprises an aliphatic dicarboxylic acid unit other than a succinic acid unit, for example, it may comprise an aliphatic dicarboxylic acid unit having 1 to 8 carbon atoms and / or 37 or more carbon atoms. Specific examples of the biodegradable polyester resin (d) include polybutylene succinate (PBS) and polybutylene succinate adipate (PBSA).

[0058] [Polyhydroxyalkanoate] Polyhydroxyalkanoate (hereinafter sometimes referred to as PHA) is a compound represented by the general formula: [-CHR １０１ -CH ２ -CO-O-] (wherein, R １０１ is an alkyl group having 1 to 15 carbon atoms.) and contains 3-hydroxybutyrate units as a main constituent component. From the viewpoint of moldability and heat resistance, the polyhydroxyalkanoate preferably contains 80 mol % or more, and more preferably 85 mol % or more, of 3-hydroxybutyrate units as constituent units. The polyhydroxyalkanoate is preferably produced by a microorganism.

[0059] Specific examples of polyhydroxyalkanoates include poly(3-hydroxybutyrate) homopolymer resin, poly(3-hydroxybutyrate-co-3-hydroxypropionate) copolymer resin, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer resin, poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) copolymer resin, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin, poly(3-hydroxybutyrate) homopolymer resin, poly(3-hydroxybutyrate) copolymer ... Examples of suitable copolymer resins include poly(3-hydroxybutyrate-co-3-hydroxyheptanoate) copolymer resins, poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) copolymer resins, poly(3-hydroxybutyrate-co-3-hydroxynonanoate) copolymer resins, poly(3-hydroxybutyrate-co-3-hydroxydecanoate) copolymer resins, poly(3-hydroxybutyrate-co-3-hydroxyundecanoate) copolymer resins, and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer resins. From the viewpoint of moldability and the resulting biodegradable laminate, the polyhydroxyalkanoate is preferably a poly(3-hydroxybutyrate) homopolymer resin, a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer resin, a poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) copolymer resin, a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin, or a poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer resin, with a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin being particularly preferred.

[0060] In polyhydroxyalkanoates, the constituent ratio of 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) to a copolymerized comonomer such as 3-hydroxyhexanoate (hereinafter sometimes referred to as 3HH), i.e., the monomer ratio in the copolymer resin, is preferably 3-hydroxybutyrate / comonomer = 97 / 3 to 80 / 20 (mol % / mol %), and more preferably 95 / 5 to 85 / 15 (mol % / mol %), from the viewpoints of molding processability and molded product quality. Having this comonomer ratio within the above range prevents the molding temperature and the thermal decomposition temperature from becoming close to each other, making molding easier and preventing a decrease in productivity due to slow crystallization of the polyhydroxyalkanoate.

[0061] The ratio of each monomer in polyhydroxyalkanoate can be measured, for example, by gas chromatography as follows. To approximately 20 mg of dry PHA, 2 ml of a sulfuric acid / methanol mixture (15 / 85 (mass ratio)) and 2 ml of chloroform are added, the mixture is sealed, and heated at 100°C for 140 minutes to obtain the methyl ester of the PHA decomposition product. After cooling, 1.5 g of sodium bicarbonate is added little by little to neutralize the mixture, and the mixture is allowed to stand until the evolution of carbon dioxide gas stops. After adding 4 ml of diisopropyl ether and mixing thoroughly, the monomer unit composition of the PHA decomposition product in the supernatant is analyzed by capillary gas chromatography to determine the ratio of each monomer in the copolymer resin.

[0062] The weight-average molecular weight (hereinafter sometimes referred to as Mw) of polyhydroxyalkanoate is usually 200,000 or more and 2,500,000 or less, as determined by gel permeation chromatography (GPC) using monodisperse polystyrene as the standard substance. Because of advantages in terms of moldability and mechanical strength, the weight-average molecular weight (Mw) of polyhydroxyalkanoate is preferably 250,000 or more and 2,000,000 or less, more preferably 300,000 or more and 1,000,000 or less. Having a weight-average molecular weight within the above range allows for good mechanical properties to be maintained and allows for easier molding and processing.

[0063] The melt flow rate (MFR) of the polyhydroxyalkanoate is a value measured at 190°C under a load of 2.16 kg according to JIS K7210 (2014), and is preferably 1 g / 10 min or more and 100 g / 10 min or less. From the viewpoints of moldability and mechanical strength, the MFR of the polyhydroxyalkanoate is more preferably 50 g / 10 min or less, and particularly preferably 30 g / 10 min or less. The MFR of the polyhydroxyalkanoate can be adjusted by the molecular weight.

[0064] The melting point of the polyhydroxyalkanoate is preferably 120° C. or higher, more preferably 130° C. or higher, and is preferably 170° C. or lower, more preferably 160° C. or lower, and particularly preferably lower than 150° C. When there are multiple melting points, it is preferable that at least one of the melting points is within the above range.

[0065] Polyhydroxyalkanoates are produced by, for example, microorganisms such as Alcaligenes eutrophus AC32 strain, which is obtained by introducing a PHA synthase gene derived from Aeromonas caviae into Alcaligenes eutrophus (international deposit under the Budapest Treaty, international depository authority: National Institute of Advanced Industrial Science and Technology International Patent Organism Depositary (6-1 Central, 1-1 Higashi, Tsukuba, Ibaraki Prefecture, Japan), original deposit date: August 12, 1996, transferred on August 7, 1997, deposit number FERM BP-6038 (transferred from original deposit FERM P-15786)) (J. Bacteriol., 179, 4821 (1997)).

[0066] Commercially available polyhydroxyalkanoates can also be used. Commercially available polyhydroxyalkanoates containing 3-hydroxybutyrate units and 3-hydroxyhexanoate units as the main structural units include Kaneka Corporation's "Aonilex (registered trademark) X131N," "Aonilex (registered trademark) X131A," "Aonilex (registered trademark) 151A," "Aonilex (registered trademark) 151C," "PHBH (registered trademark) X331N," "PHBH (registered trademark) X131A," "PHBH (registered trademark) 151A," and "PHBH (registered trademark) 151C." These polyhydroxyalkanoates are not limited to a single type, and a blend of two or more types of polyhydroxyalkanoates differing in the type and ratio of structural units, production method, physical properties, etc. can be used.

[0067] <Inorganic Filler (e)> Examples of the inorganic filler (e) include anhydrous silica, mica, talc, mica, clay, titanium oxide, calcium carbonate, diatomaceous earth, allophane, bentonite, potassium titanate, zeolite, sepiolite, smectite, kaolin, kaolinite, glass, limestone, carbon, wollastonite, calcined perlite, silicates such as calcium silicate and sodium silicate, hydroxides such as aluminum oxide, magnesium carbonate and calcium hydroxide, and salts such as ferric carbonate, zinc oxide, iron oxide, aluminum phosphate and barium sulfate, and the like. Preferred are talc, mica, clay, calcium carbonate, and zeolite.

[0068] Some inorganic fillers, such as calcium carbonate and limestone, have soil conditioner properties. When an aliphatic polyester resin composition containing a biomass-derived aliphatic polyester resin (a) containing a particularly large amount of these inorganic fillers is used, the inorganic filler remains after biodegradation in soil and functions as a soil conditioner, thereby enhancing its usefulness as a green plastic. Inorganic fillers can also be classified by their shape. Inorganic fillers include fibrous, granular, plate-like, and needle-like fillers. Granular and plate-like fillers are preferred, with plate-like fillers being particularly preferred. Examples of plate-like fillers include talc, kaolin, mica, clay, sericite, glass flakes, synthetic hydrotalcite, various metal foils, graphite, molybdenum disulfide, tungsten disulfide, boron nitride, plate-like iron oxide, plate-like calcium carbonate, and plate-like aluminum hydroxide. From the viewpoints of ease of compounding, rigidity, injection moldability, decomposability, improved moisture permeability to water vapor and the like, and enhanced deodorizing effect, it is preferable to use talc, mica, clay, calcium carbonate, or zeolite.

[0069] For ease of handling, the inorganic filler preferably has an average particle size of 0.5 μm or more, more preferably 0.6 μm or more, even more preferably 0.7 μm or more, and particularly preferably 1.0 μm or more, while the average particle size of the inorganic filler is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

[0070] The method for measuring the average particle size of the inorganic filler is not particularly limited, and a specific example of the measuring method is a method of measuring by a laser scattering method using a Microtrac MT3300EXII manufactured by Microtrac Bell.

[0071] The inorganic filler may be used alone or in any combination of two or more kinds in any ratio.

[0072] Specific examples of talc that can be suitably used as the inorganic filler include Microace manufactured by Nippon Talc, and MG113 and MG115 manufactured by Fuji Talc Kogyo.

[0073] [Contents of Aliphatic Polyester Resin (a) and Optional Components in the First Layer] The content of the aliphatic polyester resin (a) in the first layer is not particularly limited, but from the viewpoints of its fluidity, roll release property, home compostability, and the physical properties (strength, appearance) of the molded product, it is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, particularly preferably 15% by mass or more, based on the first layer, and may be 20% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, more than 42% by mass, or even 50% by mass or more. The upper limit of the content is not particularly limited, but is, for example, 100% by mass or less. In the case where the biodegradable polyester resin (d) and / or inorganic filler is contained, it is appropriately adjusted depending on the content of these optional components. Furthermore, when recycled raw material components (recycled products) obtained by regrind, which will be described later, are used in part or all of the first layer, the recycled raw material components contain aliphatic polyester resin (a), and therefore the content of the recycled products is also appropriately adjusted according to the content of the recycled products.

[0074] Specifically, when the first layer contains an aliphatic polyester resin (a) and a biodegradable polyester-based resin (d), the mass ratio of the two components relative to the aliphatic polyester resin (a) is, for example, preferably 0% by mass or more and 40% by mass or less, particularly preferably 3% by mass or more and 35% by mass or less, and even more preferably 5% by mass or more and 30% by mass or less. When the content of the biodegradable polyester-based resin (d) in the first layer is within the above range, the biodegradable laminate according to the present invention can achieve excellent biodegradability, particularly excellent home compostability, and further improved moldability.

[0075]

[0023] When the first layer contains an aliphatic polyester resin (a), a biodegradable polyester-based resin (d), and an inorganic filler, the mass ratio of the inorganic filler (e) to the total mass of the aliphatic polyester resin (a) and the biodegradable polyester-based resin (d) is preferably 0% by mass or more and 50% by mass or less, particularly preferably 50% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less. When the content ratio of the inorganic filler is within the above range, the water vapor barrier property and oxygen barrier property due to the incorporation of the inorganic filler can be further improved, and further improvements in excellent biodegradability and moldability (roll release property) and mechanical strength such as impact resistance can be achieved.

[0076] <Other Resins> The first layer may contain resins other than the aliphatic polyester resin (a) and the optional biodegradable polyester resin (d) (hereinafter also referred to as "other resins"), as long as the effects of the present invention are not impaired. Examples of other resins include synthetic resins such as aromatic polyester resins, polycarbonate, polyamide, polystyrene, polyolefin, acrylic resin, amorphous polyolefin, ABS, AS (acrylonitrile styrene), polycaprolactone, polyvinyl alcohol, and cellulose ester, as well as biodegradable resins (for example, polylactic acid, and aliphatic-aromatic polyester resins such as polybutylene adipate terephthalate (PBAT), polybutylene succinate terephthalate (PBST), and polybutylene sebacate terephthalate (PBSeT). The other resins in the first layer may include at least one resin selected from the group consisting of the resins listed above.

[0077] In order to more reliably obtain the effects of the present invention due to the first layer containing the aliphatic polyester resin (a), the content of the other resin in the first layer is preferably 0 to 50 mass%, particularly 0 to 30 mass%, and even more preferably 0 to 20 mass%, based on the total resin components in the first layer.

[0078] <Other Components> The aliphatic polyester resin composition of the present invention may contain various additives such as lubricants, plasticizers, antistatic agents, antioxidants, light stabilizers, UV absorbers, dyes, pigments, hydrolysis inhibitors, crystal nucleating agents, antiblocking agents, light resistance agents, plasticizers, heat stabilizers, flame retardants, release agents, antifogging agents, surface wetting improvers, incineration aids, dispersing aids, various surfactants, slip agents, etc., as well as fine powders of animal or plant substances such as starch, cellulose, paper, wood flour, chitin / chitosan, coconut shell powder, and walnut shell powder, or mixtures thereof, as "other components." The aliphatic polyester resin composition of the present invention may also contain functional additives such as freshness-preserving agents and antibacterial agents. These may be added in any amount within the range that does not impair the effects of the present invention, and may be used alone or in combination of two or more.

[0079] In order not to impair the physical properties of the aliphatic polyester resin composition of the present invention, it is usually preferable that the total amount of the components to be mixed is 0.01 mass % or more and 40.00 mass % or less relative to the total amount of the aliphatic polyester resin composition of the present invention.

[0080] Among the above-mentioned other components, the antifogging agent may be kneaded into the aliphatic polyester resin composition in advance, or may be applied to the surface of the molded article after molding. Specifically, the antifogging agent used is preferably an ester surfactant of a saturated or unsaturated aliphatic carboxylic acid having 4 to 20 carbon atoms and a polyhydric alcohol.

[0081] Examples of slip agents include unsaturated and saturated fatty acid amides and unsaturated and saturated fatty acid bisamides, which are made from unsaturated and saturated fatty acids having 6 to 30 carbon atoms. Most preferred examples of slip agents include erucic acid amide, oleic acid amide, stearic acid amide, and their bisamides. These can be blended in any amount within a range that does not impair the effects of the present invention, and one type may be used alone, or two or more types may be used in combination.

[0082] Examples of the anti-blocking agent include saturated fatty acid amides having 6 to 30 carbon atoms, saturated fatty acid bisamides, methylolamide, ethanolamide, natural silica, synthetic silica, synthetic zelite, and talc.

[0083] Specific examples of the light stabilizer include bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, 2-(3,5-di-t-butyl-4-hydroxyphenyl)-2-n-butyl-bis(2,2,6,6-tetramethyl-4-piperidyl)malonate, 2-(3,5-di-t-butyl-4-hydroxyphenyl)-2-n-butyl-bis(1,2,2,6,6-pentamethyl-4-piperidyl)malonate, 2-(3,5-di-t-butyl-4-hydroxyphenyl)-2-n-butyl-bis(1,2,2,6,6-pentamethyl-4-piperidyl)malonate, 2-(3,5-di-t-butyl-4-hydroxyphenyl)- hydroxybenzyl)-2-n-butyl-bis(2,2,6,6-tetramethyl-4-piperidyl)malonate, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butyl-bis(1,2,2,6,6-pentamethyl-4-piperidyl)malonate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, mixed(2,2,6,6-tetramethyl-4-piperidyl / tridecyl)-1,2,3,4-butanetetracarboxylate tetracarboxylate, mixed (1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl)-1,2,3,4-butanetetracarboxylate, mixed {2,2,6,6-tetramethyl-4-piperidyl / β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro[5.5]undecane]diethyl}-1,2,3,4-butanetetracarboxylate, mixed {1,2,2,6,6-pentamethyl-4-piperidyl / β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro[5.5]undecane]diethyl}-1,2,3,4- butane tetracarboxylate, 1,2-bis(3-oxo-2,2,6,6-tetramethyl-4-piperidyl)ethane, 1-(3,5-di-t-butyl-4-hydroxyphenyl)-1,1-bis(2,2,6,6-tetramethyl-4-piperidyloxycarbonyl)pentane, poly[1-oxyethylene(2,2,6,6-tetramethyl-1,4-piperidyl)oxysuccinyl], poly[2-(1,1,4-trimethylbutylimino)-4,6-triazinediyl-(2,2,6,6-tetramethyl-4-piperidyl)iminohexamethylene-(2,2,6,6-tetramethyl-4-piperidyl)imino], N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate and its N-methyl compound, polycondensate of succinic acid and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, etc.

[0084] Among these, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butyl-bis(1,2,2,6,6-pentamethyl-4-piperidyl)malonate are particularly preferred.

[0085] Examples of ultraviolet absorbers include benzophenone-based, benzotriazole-based, salicylic acid-based, and cyanoacrylate-based ultraviolet absorbers. Among these ultraviolet absorbers, benzotriazole-based ultraviolet absorbers are preferred, and specific examples include 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole and 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy-phenol.

[0086] Antioxidants include BHT (dibutylhydroxytoluene), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,3',3'',5,5',5''-hexa-tert-butyl-α,α',α''-(mesitylene-2,4,6-triyl)tri-p-cresol, octadecyl-3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-xylyl)methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, calcium diethylbis[{3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl}methyl] hindered phenol-based antioxidants such as phosphonates, bis(2,2'-dihydroxy-3,3'-di-tert-butyl-5,5'-dimethylphenyl)ethane, N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl)-4-hydroxyphenyl]propionamide, tridecyl phosphite, diphenyldecyl phosphite, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diylbisphosphonite Examples of antioxidants include phosphorus-based antioxidants such as bis[2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethyl ester phosphorous acid and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, lactone-based antioxidants such as the reaction product of 3-hydroxy-5,7-di-tert-butyl-furan-2-one and xylene, sulfur-based antioxidants such as dilauryl thiodipropionate and distearyl thiodipropionate, and mixtures of two or more of these. Among these, hindered phenol-based antioxidants are preferably used.

[0087] Preferred hindered phenol-based antioxidants include Irganox 3790, Irganox 1330, Irganox 1010, Irganox 1076, Irganox 3114, Irganox 1425WL, Irganox 1098, Irganox HP2225FL, Irganox HP2341, and Irgafos XP-30 (all manufactured by BASF), and Sumilizer BBM-S (manufactured by Sumitomo Chemical Co., Ltd.). The most preferred antioxidants are Irganox 1010 (pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) and Irganox 1330 (3,3',3",5,5',5"-hexa-tert-butyl-α,α',α"-mesitylene-2,4,6-triyl)tri-p-cresol).

[0088] <Method for Producing Aliphatic Polyester Resin Composition> To form the first layer, an aliphatic polyester resin composition is produced by mixing at least the aliphatic polyester resin (a) and, if necessary, the optional components described above.

[0089] The above-mentioned mixing is carried out by mixing the aliphatic polyester resin (a) and any optional components in a predetermined ratio simultaneously or in any order using a mixer such as a tumbler, a V-type blender, a Nauta mixer, a Banbury mixer, a kneading roll, or an extruder, and preferably by melt-kneading.

[0090] The kneader used for mixing may be a melt kneader. Although there is no limitation on the type of single-screw extruder or twin-screw extruder, a twin-screw extruder is more preferable for the purpose of achieving melt kneading depending on the properties of the aliphatic polyester resin (a) and optional components used.

[0091] The temperature during melt-kneading is not particularly limited, but is preferably in the range of 120 to 220° C., and more preferably 130 to 180° C. By carrying out melt-kneading within the above temperature range, it is possible to shorten the time required for the melting reaction, prevent deterioration of color tone and thermal decomposition associated with resin degradation, and further improve practical physical properties such as impact resistance and moist heat resistance.

[0092] The melt-kneading time is preferably 20 seconds to 20 minutes, particularly preferably 30 seconds to 15 minutes, from the viewpoint of more uniformly mixing the materials to be kneaded and more reliably avoiding resin deterioration. It is preferable to set the melt-kneading temperature and time conditions so as to satisfy this melt-kneading time.

[0093] The aliphatic polyester resin composition containing at least the aliphatic polyester resin (a) may contain a recycled raw material component (recycled product) obtained by regrind. For example, the first layer may be formed from a recycled raw material component (recycled product) obtained by finely grinding or heat-melting scrap generated in the process of producing the biodegradable laminate of a preferred embodiment of the present invention and then repelletizing the scrap.

[0094] <Second Layer (Adhesive Layer)> An adhesive resin composition containing a modified polyester resin (F) that is suitably used for the second layer as an adhesive layer located between the first layer and the third layer in the biodegradable laminate of the present invention will be described.

[0095] The modified polyester resin (F) contained in the adhesive resin composition is obtained by graft-modifying a polyester resin (f) with an α,β-unsaturated carboxylic acid and / or its anhydride. The polyester resin (f) primarily contains at least one polyester resin selected from the group consisting of aliphatic polyester resins defined similarly to the aliphatic polyester resin (a) contained in the first layer, biodegradable polyester resins defined similarly to the biodegradable polyester resin (d) that may be contained in the first layer, biodegradable polyester resins having a third repeating structural unit derived from an aliphatic diol and a fourth repeating structural unit derived from an aliphatic dicarboxylic acid, wherein the fourth repeating structural unit includes a repeating structural unit derived from succinic acid, and aliphatic-aromatic polyester resins described below. The aliphatic polyester resin and biodegradable polyester resin contained in the second layer may also be referred to as "aliphatic polyester resin (a)" and "aliphatic polyester resin (d)," respectively. Here, the aliphatic polyester resin (a) and / or aliphatic polyester resin (d) used as raw materials for the modified polyester resin (F) may be exactly the same as the aliphatic polyester resin (a) and / or biodegradable polyester resin (d) contained in the first layer, or may be different within the scope of the definition of the aliphatic polyester resin (a) and the scope of the definition of the biodegradable polyester resin (d) containing the third repeating structural unit and the fourth repeating structural unit as main structural units.

[0096] With respect to the polyester-based resin (f), "mainly containing" typically refers to a component contained in the polyester-based resin (f) at a concentration of 80% by mass or more. The polyester-based resin (f) may contain other resins as long as the effects of the present invention are not impaired, as long as it primarily contains at least one polyester resin selected from the group consisting of aliphatic polyester resin (a), aliphatic polyester resin (d), and aliphatic-aromatic polyester resin. Examples of other resins that may be contained in the polyester-based resin (f) include synthetic resins such as polyhydroxyalkanoates, aromatic polyester resins, polycarbonates, polyamides, polystyrenes, polyolefins, acrylic resins, amorphous polyolefins, ABS, AS (acrylonitrile styrene), polycaprolactone, polyvinyl alcohol, and cellulose esters, as well as polylactic acid.

[0097] From the viewpoints of high biodegradability, processability and adhesiveness when used as an adhesive layer in a biodegradable laminate, the polyester resin (f) is preferably composed of only at least one polyester resin selected from the group consisting of aliphatic polyester resin (a), aliphatic polyester resin (d) and aliphatic-aromatic polyester resin.

[0098] From the viewpoint of improving the mechanical strength and adhesiveness when formed into a biodegradable resin laminate, the polyester resin (f) of the present invention preferably contains an aliphatic polyester resin (a) and an aliphatic-aromatic polyester resin (f), an aliphatic polyester resin (d) and an aliphatic-aromatic polyester resin (f), or an aliphatic-aromatic polyester resin. By containing an aliphatic-aromatic polyester resin, primary processability is improved. When the polyester resin (f) contains an aliphatic polyester resin (a) and / or an aliphatic polyester resin (d) and an aliphatic-aromatic polyester resin, the proportions of the aliphatic polyester resin (a), the aliphatic polyester resin (d), and the aliphatic-aromatic polyester resin are preferably 15 to 50 mass% in total of the aliphatic polyester resin (a) and the aliphatic polyester resin (d), and 50 to 85 mass% of the aliphatic-aromatic polyester resin, based on the total amount of the aliphatic polyester resin (a), the aliphatic polyester resin (d), and the aliphatic-aromatic polyester resin, from the viewpoint of biodegradability and processability.

[0099] Examples of the aliphatic-aromatic polyester resin contained in the polyester resin (f) include those in which at least a portion of the repeating units of the above-mentioned aliphatic polyester resin (a) and / or aliphatic polyester resin (d) have been replaced with aromatic compound units, preferably polyester resins containing aliphatic diol units, aliphatic dicarboxylic acid units, and aromatic dicarboxylic acid units as main constituent units, in which a portion of the aliphatic dicarboxylic acid units of the above-mentioned aliphatic polyester resin (a) or aliphatic polyester resin (d) have been replaced with aromatic dicarboxylic acid units.

[0100] Examples of aromatic compound units include aromatic diol units having an aromatic hydrocarbon group which may have a substituent, aromatic dicarboxylic acid units having an aromatic hydrocarbon group which may have a substituent, and aromatic oxycarboxylic acid units having an aromatic hydrocarbon group which may have a substituent. The aromatic hydrocarbon group may be a single ring, or may be one in which multiple rings are bonded to or condensed with each other. Specific examples of aromatic hydrocarbon groups include a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a dinaphthylene group, and a diphenylene group.

[0101] Specific examples of aromatic dicarboxylic acid components that provide aromatic dicarboxylic acid units include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and diphenyldicarboxylic acid. Among these, terephthalic acid is preferred. The aromatic dicarboxylic acid component may be a derivative of an aromatic dicarboxylic acid compound. For example, derivatives of the aromatic dicarboxylic acid components exemplified above are preferred, and among these, lower alkyl esters having 1 to 4 carbon atoms and acid anhydrides are mentioned. Specific examples of derivatives of aromatic dicarboxylic acid compounds include lower alkyl esters such as methyl esters, ethyl esters, propyl esters, and butyl esters of the aromatic dicarboxylic acid components exemplified above; cyclic acid anhydrides of the aromatic dicarboxylic acid components exemplified above, such as succinic anhydride; and the like. Among these, dimethyl terephthalate is preferred.

[0102] Specific examples of aromatic diol components that provide aromatic diol units include xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, and bis(4-β-hydroxyethoxyphenyl)sulfonic acid. The aromatic diol component may be a derivative of an aromatic diol compound. Alternatively, the aromatic diol component may be a compound having a structure in which a plurality of aliphatic diol compounds and / or aromatic diol compounds are dehydrated and condensed together.

[0103] Specific examples of aromatic oxycarboxylic acid components that provide aromatic oxycarboxylic acid units include p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid. The aromatic oxycarboxylic acid component may be a derivative of an aromatic oxycarboxylic acid compound. Alternatively, it may be a compound (oligomer) having a structure in which a plurality of aliphatic oxycarboxylic acid compounds and / or aromatic oxycarboxylic acid compounds are dehydrated and condensed with each other. That is, an oligomer may be used as a raw material.

[0104] When the aromatic compound component that provides these aromatic compound units has optical isomers, any of the D-isomer, L-isomer, and racemic isomer may be used. Furthermore, the aromatic compound component is not limited to the above examples, as long as it can provide an aromatic compound unit. Furthermore, the aromatic compound component may be used alone, or two or more kinds may be used in any combination and ratio.

[0105] As the aliphatic-aromatic polyester resin, it is preferable to use an aromatic dicarboxylic acid component as the component that provides the aromatic compound unit, and in this case, the content of the aromatic dicarboxylic acid unit is preferably 10 mol% or more and 80 mol% or less, and more preferably 30 mol% or more and 70 mol% or less, based on the total amount of the aliphatic dicarboxylic acid unit and the aromatic dicarboxylic acid unit (100 mol%). Furthermore, it is preferable to use terephthalic acid as the aromatic dicarboxylic acid component, and the aliphatic-aromatic polyester resin is preferably polybutylene terephthalate adipate, polybutylene terephthalate succinate, or polybutylene sebacate terephthalate resin.

[0106] The aliphatic-aromatic polyester resin can be produced in the same manner as the aliphatic polyester resin (a) described above, using at least an aromatic compound component as a raw material.

[0107] The molecular weight of the aliphatic-aromatic polyester resin used in the present invention can be measured by gel permeation chromatography (GPC), and the weight average molecular weight (Mw) using monodisperse polystyrene as the standard substance is usually 10,000 to 1,000,000. The weight average molecular weight (Mw) of the aliphatic-aromatic polyester resin is preferably 30,000 to 800,000, more preferably 50,000 to 600,000, because this is advantageous in terms of moldability and mechanical strength.

[0108] The melt flow rate (MFR) of the aliphatic-aromatic polyester resin is a value measured at 190°C under a load of 2.16 kg according to JIS K7210 (2014), and is typically 0.1 g / 10 min or more and 100 g / 10 min or less. From the viewpoint of moldability and mechanical strength, the MFR of the aliphatic-aromatic polyester resin is preferably 50 g / 10 min or less, particularly preferably 30 g / 10 min or less. The MFR of the aliphatic-aromatic polyester resin can be adjusted by the molecular weight.

[0109] The melting point of the aliphatic-aromatic polyester resin is usually 60°C or higher, preferably 70°C or higher, more preferably 80°C or higher and 150°C or lower, more preferably 140°C or lower, and particularly preferably 120°C or lower. When there are multiple melting points, it is preferable that at least one of the melting points is within the above range. The elastic modulus of the aliphatic-aromatic polyester resin is preferably 100 to 1000 MPa. When the melting point of the aliphatic-aromatic polyester resin is within the above range, better moldability can be obtained. Furthermore, when the elastic modulus of the aliphatic-aromatic polyester resin is 100 MPa or higher and 1000 MPa or lower, better moldability and impact resistance can be obtained.

[0110] The method for adjusting the melting point and elastic modulus of the aliphatic-aromatic polyester resin is not particularly limited, but for example, they can be adjusted by selecting the type of copolymerization component of the aliphatic dicarboxylic acid component other than the aromatic dicarboxylic acid component, adjusting the copolymerization ratio of each, or combining them.

[0111] In the present invention, the aliphatic-aromatic polyester resin is not limited to one type, and a blend of two or more types of aliphatic-aromatic polyester resins differing in the types and ratios of constituent units, production methods, physical properties, etc. can be used.

[0112] <Modified polyester resin (F)> The modified polyester resin (F) includes a resin obtained by graft-modifying the above-mentioned polyester resin (f) with an α,β-unsaturated carboxylic acid and / or an anhydride thereof. The polyester resin (f) is biodegradable because it contains the aliphatic polyester resin (a), the aliphatic polyester resin (d), and / or an aliphatic-aromatic polyester resin. Furthermore, the modified polyester resin (F) obtained by graft-modifying the polyester resin (f) with an α,β-unsaturated carboxylic acid and / or an anhydride thereof is also biodegradable because its basic skeleton is an aliphatic polyester or an aliphatic-aromatic polyester that has been slightly modified.

[0113] The weight average molecular weight of the polyester resin (f), as a polystyrene-equivalent value measured by GPC, is usually 5,000 to 1,000,000, preferably 20,000 to 500,000, and particularly preferably 50,000 to 400,000. When the weight average molecular weight of the polyester resin (f) is within the above range, it is possible to prevent the melt viscosity from becoming too high, which makes melt molding difficult, and it is also possible to prevent the molded product from becoming embrittled.

[0114] Examples of commercially available polyester resins (f) include "Ecoflex" manufactured by BASF, which contains a condensation polymer of adipic acid / terephthalic acid and 1,4-butanediol as the main component, and "BioPBS" manufactured by PTTMCC Biochem, which contains a condensation polymer of succinic acid / adipic acid / 1,4-butanediol as the main component. Examples of polyhydroxyalkanoates that may be contained in the polyester resin (f) as an optional component include "PHBH (registered trademark)" manufactured by Kaneka Corporation.

[0115] Specific examples of the α,β-unsaturated carboxylic acid and / or anhydride thereof used for graft-modifying the polyester resin (f) include α,β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; α,β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citrus acid, tetrahydrophthalic acid, crotonic acid, and isocrotonic acid, as well as their derivatives and anhydrides. Anhydrides of α,β-unsaturated dicarboxylic acids are preferred. These α,β-unsaturated carboxylic acids and / or anhydrides may be used singly or in combination of two or more. The method for graft-modifying the polyester resin (f) with the α,β-unsaturated carboxylic acid and / or its derivative is not particularly limited, and known methods can be used. While graft-modification can be achieved by thermal reaction alone, it is preferable to use a radical initiator to enhance reactivity. Examples of reaction methods include solution reaction, suspension reaction, and reaction in a molten state without using a solvent, among which molten reaction is preferred.

[0116] Two or more types of polyester resins (f) can be used. In this case, the polyester resins (f) can be mixed in advance and then graft-modified with an α,β-unsaturated carboxylic acid and / or a derivative thereof to form a modified polyester resin (F), or two or more types of modified polyester resins (F) can be mixed.

[0117] The modified polyester resin (F) may be mixed with one or more polyester resins (f) as long as the performance of the modified polyester resin (F) is not impaired.

[0118] Examples of the melting method include a method in which the polyester resin (f), the α,β-unsaturated carboxylic acid and / or a derivative thereof, and a radical initiator are mixed in advance and then melt-kneaded in a kneader to cause a reaction, and a method in which the α,β-unsaturated carboxylic acid and / or a derivative thereof, and a radical initiator are blended with the polyester resin (f) in a molten state in a kneader.

[0119] As a mixer used when premixing the raw materials, a Henschel mixer, a ribbon blender, or the like can be used, and as a kneader used for melt kneading, a single-screw or twin-screw extruder, a roll, a Banbury mixer, a kneader, a Brabender mixer, or the like can be used.

[0120] The temperature during melt-kneading may be set appropriately within a temperature range that is equal to or higher than the melting point of the polyester resin (f) and does not cause thermal degradation, preferably 100 to 270°C, more preferably 160 to 250°C.

[0121] The amount of α,β-unsaturated carboxylic acid and / or its derivative used is usually 0.0001 to 5 parts by mass, particularly 0.001 to 4 parts by mass, and particularly preferably 0.02 to 3 parts by mass, per 100 parts by mass of polyester resin (f). If the amount of α,β-unsaturated carboxylic acid and / or its derivative used is too small, a sufficient number of polar groups will not be introduced into polyester resin (f), and interlayer adhesion, particularly adhesion to a PVA-based resin layer, will tend to be insufficient. If the amount of α,β-unsaturated carboxylic acid and / or its derivative used is too large, ungrafted α,β-unsaturated carboxylic acid and / or its derivative may remain in the resin, which will tend to result in poor appearance and the like.

[0122] The radical initiator is not particularly limited, and known radical initiators can be used. Examples thereof include organic and inorganic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-bis(t-butyloxy)hexane, 3,5,5-trimethylhexanoyl peroxide, t-butyl peroxybenzoate, benzoyl peroxide, m-toluoyl peroxide, dicumyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, dibutyl peroxide, methyl ethyl ketone peroxide, potassium peroxide, and hydrogen peroxide; azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(isobutylamido)dihalide, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] and azodi-t-butane; and carbon radical generators such as dicumyl. These may be used alone or in combination of two or more.

[0123] The amount of radical initiator used is usually 0.00001 to 2.00000 parts by mass, particularly 0.00010 to 1.50000 parts by mass, and particularly 0.0010 to 1.00000 parts by mass per 100 parts by mass of polyester resin (f). If the amount of radical initiator used is too small, graft polymerization may not occur sufficiently, and sufficient interlayer adhesion may not be obtained. If the amount of radical initiator used is too large, the crosslinking reaction of polyester resin (f) may proceed, resulting in an unstable extrusion rate during hot melt molding, which tends to result in a poor appearance of the multilayer molded product.

[0124] The content of unsaturated carboxylic acid and / or its derivative in modified polyester resin (f) is not limited, but is usually 0.01% by mass or more, preferably 0.02% by mass or more, more preferably 0.03% by mass or more, and is usually 5.00% by mass or less, preferably 4.00% by mass or less, more preferably 3.00% by mass or less. The content of unsaturated carboxylic acid and / or its derivative in modified polyester resin (f) is preferably 0.01% by mass or more and 5.00% by mass or less, particularly preferably 0.02% by mass or more and 4.00% by mass or less, and even more preferably 0.03% by mass or more and 3.00% by mass or less. When the content of unsaturated carboxylic acid and / or its derivative in modified polyester resin (F) is within the above range, interlayer adhesion, particularly adhesion to layer A, can be strengthened, and stability during hot melt molding can be further improved. The content of unsaturated carboxylic acid and / or its derivative in modified polyester resin (F) is １ It can be determined from a spectrum obtained by H-NMR measurement.

[0125] The adhesive layer of the biodegradable laminate of the present invention may contain only one type of the modified polyester resin (F) or may contain two or more types thereof.

[0126] The third layer is a layer that provides gas barrier properties in the biodegradable laminate according to the present invention, and is laminated on at least one side of the first layer via the second layer described above. The third layer contains at least a polyvinyl alcohol (PVA) resin.

[0127] The content of the PVA-based resin in the third layer is typically 70% by mass or more, particularly 80% by mass or more, and even 90% by mass or more, relative to the mass of the third layer. There is no particular upper limit, but it is, for example, 100% by mass or less. Therefore, the content of the PVA-based resin in the third layer is preferably 70 to 100% by mass, particularly preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. By ensuring that the content of the PVA-based resin in the third layer is within the above range, the third layer can be provided with sufficient gas barrier properties.

[0128] PVA-based resins are resins primarily composed of vinyl alcohol structural units, obtained by saponifying polyvinyl ester-based resins obtained by copolymerizing vinyl ester-based monomers, and are composed of vinyl alcohol structural units and vinyl ester structural units in amounts corresponding to the degree of saponification.

[0129] Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, and vinyl versatate, with vinyl acetate being economically preferred.

[0130] The average degree of polymerization of the PVA-based resin (measured in accordance with JIS K6726 (1994)) is usually 200 to 1,800, particularly 300 to 1,500, and more preferably 300 to 1,000. When the average degree of polymerization of the PVA-based resin is within the above range, the third layer can be provided with more sufficient mechanical strength. Furthermore, when the third layer is formed by hot melt molding, the resin composition for forming the third layer can be imparted with sufficient fluidity, improving moldability and more reliably preventing thermal decomposition of the resin due to shear heat generation during molding.

[0131] The saponification degree of the PVA-based resin (measured in accordance with JIS K6726 (1994)) is usually 80 to 100 mol %, particularly 90 to 99.9 mol %, and more preferably 98 to 99.9 mol %. When the saponification degree of the PVA-based resin is within the above range, the third layer can be provided with sufficient gas barrier properties.

[0132] As the PVA-based resin, those obtained by copolymerizing various monomers during the production of a polyvinyl ester-based resin and then saponifying the copolymer, or various modified PVA-based resins obtained by post-modifying unmodified PVA to introduce various functional groups can also be used.

[0133] Monomers used for copolymerization with vinyl ester monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; hydroxyl group-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, and 3,4-dihydroxy-1-butene, as well as derivatives thereof such as acylated products; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid, as well as their salts, monoesters, or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; and diacetone acrylate. olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, methallylsulfonic acid, or salts thereof; alkyl vinyl ethers, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, glycerin monoallyl ether, vinyl compounds such as 3,4-diacetoxy-1-butene; substituted vinyl acetates such as isopropenyl acetate and 1-methoxyvinyl acetate; vinylidene chloride, 1,4-diacetoxy-2-butene, vinylene carbonate, and the like.

[0134] Examples of PVA-based resins into which functional groups have been introduced by post-reaction include those having acetoacetyl groups by reaction with diketene, those having polyalkylene oxide groups by reaction with ethylene oxide, those having hydroxyalkyl groups by reaction with epoxy compounds, etc., and those obtained by reacting PVA with aldehyde compounds having various functional groups. The content of modified species in modified PVA-based resins, i.e., structural units derived from various monomers in the copolymer, or functional groups introduced by post-reaction, cannot be generalized because the properties vary greatly depending on the modified species, but is usually preferably in the range of 1 to 20 mol %, and particularly preferably 2 to 10 mol %.

[0135] Among these various modified PVA-based resins, in the present invention, a PVA-based resin having a structural unit having a 1,2-diol structure in a side chain, represented by the following general formula (101), is preferably used because it can be easily melt-molded in the method for producing the biodegradable laminate of the present invention, which will be described later.

[0136] R in general formula (101) １ , R ２ , and R ３ each independently represents a hydrogen atom or an organic group, X represents a single bond or a bonded chain, R ４ , R ５ , and R ６ each independently represents a hydrogen atom or an organic group.

[0137]

[0138] Among them, R in the 1,2-diol structural unit represented by general formula (101) １ ~R ３ , and R ４ ~R ６ are all hydrogen atoms and X is a single bond. A PVA-based resin having a structural unit k represented by the following general formula (101a) is most preferred. A PVA-based resin having a structural unit k represented by the following general formula (101a) is commercially available, for example, as "Nichigo G Polymer" (trade name, manufactured by Mitsubishi Chemical Corporation).

[0139]

[0140] R in the structural unit represented by general formula (101) １ ~R ３ , and R ４ ~R ６ may be an organic group in an amount that does not significantly impair the resin properties, and examples of the organic group include alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. Such organic groups may have functional groups, such as halogen, hydroxyl, ester, carboxylic acid, and sulfonic acid groups, as necessary.

[0141] X in the 1,2-diol structural unit represented by general formula (101) is most preferably a single bond in terms of thermal stability and stability under high temperatures and acidic conditions, but may also be a linking chain as long as it does not impair the effects of the present invention. Examples of such linking chains include hydrocarbons such as alkylene, alkenylene, alkynylene, phenylene, and naphthylene (these hydrocarbons may be substituted with halogens such as fluorine, chlorine, and bromine), as well as -O-, -(CH ２ O)r-,-(OCH ２ ) r-, -(CH ２ O) rCH ２ -, -CO-, -COCO-, -CO(CH ２ )rCO-, -CO(C ６ H ４ )CO-, -S-, -CS-, -SO-, -SO ２ -, -NR-, -CONR-, -NRCO-, -CSNR-, -NRCS-, -NRNR-, -HPO ４ -, -Si(OR) ２ -, -OSi(OR) ２ -, -OSi(OR) ２ O-, -Ti (OR) ２ -, -OTi(OR) ２ -, -OTi(OR) ２ Examples include -O-, -Al(OR)-, -OAl(OR)-, -OAl(OR)O-, etc. (each R is independently an arbitrary substituent, preferably a hydrogen atom or an alkyl group, and r is an integer of 1 to 5). Among these, from the viewpoint of stability during production or use, an alkylene group having 6 or less carbon atoms, particularly a methylene group, or -CH ２ OCH ２ - is preferred.

[0142] The method for producing such a PVA-based resin having a 1,2-diol structure in a side chain is not particularly limited, but (i) a method of saponifying a copolymer of a vinyl ester-based monomer and a compound represented by the following general formula (103), (ii) a method of saponifying and decarboxylating a copolymer of a vinyl ester-based monomer and a compound represented by the following general formula (105), or (iii) a method of saponifying and deketalizing a copolymer of a vinyl ester-based monomer and a compound represented by the following general formula (107) can be preferably used.

[0143]

[0144] R in the above general formulas (103), (105), and (107) １ , R ２ , R ３ , X, R ４ , R ５ , and R ６ are the same as in the general formula (101). ７ and R ８ are each independently a hydrogen atom or R ９ -CO- (wherein, R ９ is an alkyl group. １０ and R １１ are each independently a hydrogen atom or an alkyl group.

[0145] As for the methods (i), (ii), and (iii), for example, the methods described in Patent Document 2 can be used. Among them, in the method (i), it is preferable to use 3,4-diacyloxy-1-butene as the compound represented by general formula (105) from the viewpoint of excellent copolymerization reactivity and industrial handleability, and 3,4-diacetoxy-1-butene is particularly preferably used.

[0146] The content of 1,2-diol structural units in PVA-based resins having 1,2-diol structures in their side chains is usually 1 to 20 mol %, preferably 2 to 10 mol %, and particularly preferably 3 to 8 mol %. When the content of 1,2-diol structural units is within the above range, the effects of the 1,2-diol structures in the side chains can be more easily obtained, and the deterioration of gas barrier properties at high humidity can be more effectively prevented.

[0147] The content of 1,2-diol structural units in a PVA-based resin can be determined from the H-NMR spectrum (solvent: DMSO-d6, internal standard: tetramethylsilane) of a completely saponified PVA-based resin. Specifically, it can be calculated from the peak areas derived from hydroxyl group protons, methine protons, and methylene protons in the 1,2-diol unit, methylene protons in the main chain, and protons of hydroxyl groups linked to the main chain.

[0148] The PVA-based resin used in the present invention may be one type or a mixture of two or more types. In the case of a mixture of two or more types, a combination of the above-mentioned unmodified PVAs, an unmodified PVA and a PVA-based resin having a structural unit represented by general formula (101), a combination of PVA-based resins having a structural unit represented by general formula (101) but differing in saponification degree, polymerization degree, modification degree, etc., a combination of unmodified PVA, or a PVA-based resin having a structural unit represented by general formula (101) and another modified PVA-based resin, etc. may be used.

[0149] [Uses] The biodegradable laminate of the present invention is suitable for a wide range of uses, such as packaging materials (packaging materials) for packaging liquid, powdery, and solid materials, such as various foods, medicines, and miscellaneous goods, as well as agricultural and construction materials. Specific uses include extrusion-molded products (e.g., packaging films, sheets, trays for fresh food, coffee capsules, fishing lines, fishing nets, vegetation nets, water-retaining sheets, etc.), blown-molded products (e.g., bottles), and injection-molded products (e.g., trays for fresh food, coffee capsules, fast-food containers, outdoor leisure products, etc.). Further examples include agricultural films, coating materials, fertilizer coating materials, laminate films, plates, stretched sheets, monofilaments, nonwoven fabrics, flat yarns, staples, crimped fibers, creased tape, split yarns, composite fibers, blown bottles, shopping bags, garbage bags, compost bags, cosmetic containers, food containers, detergent containers, bleach containers, ropes, binding materials, sanitary cover stock materials, insulated boxes, cushioning films, multifilaments, synthetic paper, medical DDS such as surgical thread, sutures, artificial bones, artificial skin, microcapsules, wound dressings, etc. Among these, more preferred examples include packaging materials such as packaging films, particularly food packaging films, bags, trays, bottles, cushioning foams, fish boxes, etc., and agricultural materials such as mulching films, tunnel films, greenhouse films, sunshades, weed control sheets, ridge sheets, germination sheets, vegetation mats, seedling beds, flower pots, etc.

[0150] [Biodegradable Laminate] The biodegradable laminate of the present invention comprises a first layer containing an aliphatic polyester resin (a) laminated on at least one surface thereof with a third layer containing a PVA-based resin via an adhesive layer (second layer), and typically has a laminate structure of 3 to 15 layers, preferably 3 to 7 layers, and particularly preferably 5 to 7 layers. The order of lamination of the first, second, and third layers in the laminate structure is not particularly limited. For example, if the first layer containing an aliphatic polyester resin is designated as a, the adhesive layer (second layer) is designated as b, and the third layer containing a PVA-based resin is designated as c, any combination is possible, such as "a / b / c," "a / b / c / b / a," or "a / c / b / c / b / c / a." Furthermore, a fourth layer distinct from the first layer (e.g., having a different composition) may be formed from a recovered raw material (recycled product) obtained by finely grinding scrap generated during the laminate manufacturing process or by repelletizing it after thermal melting. In this case, from the viewpoint of the appearance of the resulting laminate, it is preferable that the content of the aliphatic polyester resin (a) contained in the fourth layer is smaller than the content of the aliphatic polyester resin (a) contained in the first layer. The stacking order of the first, second, third, and fourth layers in this laminate structure is not particularly limited, but any combination is possible, such as "a / d / b / c" or "a / d / b / c / b / d / a," where the fourth layer is designated as "d." A particularly preferred example of a laminate structure is a laminate structure in which the first layer is at least one layer selected from the group consisting of a layer in contact with outside air and a layer in contact with moisture-containing contents, in order to prevent a decrease in gas barrier performance due to moisture absorption by the third layer (a layer containing a PVA-based resin). Furthermore, a laminate structure in which the third layer is sandwiched between the first layers directly or via another layer (e.g., the second layer) is preferred.

[0151] Fig. 1 shows a partial cross-sectional view of a biodegradable laminate according to one embodiment of the present invention. The biodegradable laminate shown in Fig. 1 is composed of five layers: an outer layer 101 in contact with the outside air, an adhesive layer 103, a barrier layer 105, another adhesive layer 103, and an inner layer 107. The outer layer 101 and the inner layer 107 are first layers containing an aliphatic polyester-based resin, the barrier layer 105 is a third layer containing a PVA-based resin, and the adhesive layer 103 is a second layer. That is, the biodegradable laminate shown in Fig. 1 has the above-mentioned "a / b / c / b / a" laminate structure. Fig. 2 shows a partial cross-sectional view of a biodegradable laminate according to another embodiment. The biodegradable laminate shown in Fig. 2 is composed of seven layers: an outer layer 101a in contact with the outside air, an optional layer 102a, an adhesive layer 103a, a barrier layer 105a, an adhesive layer 103a, an optional layer 102a, and an inner layer 107a, in which the outer layer 101a and the inner layer 107a are first layers containing an aliphatic polyester-based resin, the optional layer 102a is a fourth layer distinct from the first layer (for example, having a different blending composition), the barrier layer 105a is a third layer containing a PVA-based resin, and the adhesive layer 103a is a second layer. That is, the biodegradable laminate shown in Fig. 2 has the above-mentioned "a / d / b / c / b / d / a" laminate structure.

[0152] The thickness of the biodegradable laminate of the present invention is preferably 1 to 30,000 μm, particularly preferably 3 to 13,000 μm, further preferably 10 to 3,000 μm, and particularly preferably 30 to 2,000 μm.

[0153] Regarding the thickness of each layer constituting the biodegradable laminate, the first layer containing the aliphatic polyester resin (a) is usually 0.4 to 14,000 μm, preferably 1 to 6,000 μm, and particularly preferably 4 to 1,400 μm. By keeping the thickness of the first layer within the above range, an excessive increase in hardness and excessive embrittlement of the biodegradable laminate can be prevented.

[0154] The thickness of the third layer containing a PVA-based resin is preferably 0.1 to 1000 μm, particularly preferably 0.3 to 500 μm, and even more preferably 1 to 100 μm. When the thickness of the third layer is within the above range, sufficient barrier properties can be imparted to the biodegradable laminate and the biodegradable laminate can be prevented from becoming hard or brittle.

[0155] The thickness of the second layer, which is an adhesive layer, is usually 0.1 to 500 μm, preferably 0.15 to 250 μm, and particularly preferably 0.5 to 50 μm. By having the thickness of the second layer within the above range, the first layer and the third layer can be more reliably bonded together, and the appearance of the biodegradable laminate can be prevented from being poor.

[0156] The ratio of the total thickness of the first layer to the total thickness of the third layer is usually 1 to 100, and preferably 2.5 to 50. Here, the total thickness of the first layer refers to the sum of the thicknesses of the first layers when there are multiple first layers. The same applies to the second layer. When the ratio of the total thickness of the first layer to the total thickness of the third layer is within the above range, the barrier properties of the biodegradable laminate can be made more sufficient, and an excessive increase in hardness and excessive embrittlement of the biodegradable laminate can be prevented.

[0157] The ratio of the total thickness of the second layer to the total thickness of the biodegradable laminate is usually 0.005 to 0.5, and preferably 0.01 to 0.3. Here, the total thickness of the second layer refers to the sum of the thicknesses of the second layers when there are multiple second layers. By keeping the ratio of the total thickness of the second layer to the total thickness of the biodegradable laminate within the above range, it is possible to prevent a decrease in the appearance of the biodegradable laminate and a decrease in the adhesive strength between the layers.

[0158] The biodegradable laminate of the present invention has an excellent appearance due to the first layer containing an aliphatic polyester resin (a) that can be rapidly solidified from a molten state and has excellent roll-release properties, and also has excellent mechanical strength, flexibility, high transparency, water resistance, moisture resistance, and biodegradability (particularly, home compostability). The third layer has high mechanical strength, gas barrier properties, transparency, and biodegradability. Furthermore, the first layer and the third layer are firmly bonded by the second layer, and the second layer can also be biodegradable. Furthermore, the modified polyester resin (F) contained in the second layer has high biodegradability because its basic skeleton is the aliphatic polyester resin (a) and / or an aliphatic-aromatic polyester resin. Therefore, the biodegradable laminate of the present invention can be completely biodegradable and has high water vapor barrier properties and high oxygen barrier properties.

[0159] The biodegradable laminate of the present invention can also be subjected to various secondary processes for the purpose of imparting surface functions such as chemical functions, electrical functions, magnetic functions, mechanical functions, friction / wear / lubrication functions, optical functions, thermal functions, biocompatibility, etc. Examples of secondary processes include embossing, painting, bonding, printing, metallizing (plating, etc.), machining, and surface treatments (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.).

[0160] [Method for Producing Biodegradable Laminate] The biodegradable laminate of the present invention can be produced by a conventionally known molding method. Specifically, a melt molding method or a molding method from a solution state can be used. For example, melt molding methods include a method in which an adhesive resin and a PVA-based resin are melt-extrusion laminated sequentially or simultaneously onto an aliphatic polyester-based resin film or sheet, a method in which an adhesive resin and an aliphatic polyester-based resin are melt-extrusion laminated sequentially or simultaneously onto a PVA-based resin film or sheet, or a method in which an aliphatic polyester-based resin, an adhesive resin, and a PVA-based resin are co-extruded.

[0161] Examples of molding methods from a solution state include a method in which a solution of an adhesive resin dissolved in a good solvent is solution-coated onto a film, sheet, etc. of an aliphatic polyester resin, and after drying, an aqueous solution of a PVA resin is solution-coated.

[0162] Among these, the melt molding method is preferred, and the co-extrusion method is particularly preferred, since it can be produced in one step and can give a biodegradable laminate with excellent interlayer adhesion. When the melt molding method is used, it is preferred to use a PVA-based resin having a 1,2-diol structure in the side chain.

[0163] Examples of co-extrusion methods include inflation, T-die, multi-manifold die, feed block, and multi-slot die. Examples of the shape of the die used in such co-extrusion methods include T-dies and round dies. The melt molding temperature during melt extrusion is usually in the range of 160 to 250°C, preferably 170 to 230°C, and particularly preferably 180 to 230°C.

[0164] An example of a method for producing a three-kind, five-layer biodegradable laminate having the cross section shown in FIG. 1 , in which the first, second, and third layers are laminated in the order "a, b, c, b, a" by coextrusion, is described with reference to FIG. 3 . In FIG. 3 , 201 denotes an extruder, 203 denotes a feed block, 205 denotes a T-die, and 207-1 to 207-3 denote three cooling members (cooling rolls). From each extruder 201, melt-kneaded mixtures of an aliphatic polyester resin (a) or a resin composition containing an aliphatic polyester resin (a) for forming the first layer, a modified polyester-based resin (F) or a resin composition containing a modified polyester-based resin (F) for forming the second layer, and a PVA-based resin or a resin composition containing a PVA-based resin for forming the third layer are extruded into sheets. The three sheets are then integrated in the feed block 203 in the lamination order of "a, b, c, b, a." Next, a single sheet (melt coextrusion molded product) in which the first, second, and third layers are integrated is extruded from the discharge opening of the T-die 205, passed between cooling rolls 207-1 and 207-2, wrapped around cooling roll 207-2, and allowed to solidify sufficiently on the circumferential surface of cooling roll 207-2. The solidified sheet is then peeled off from the circumferential surface of cooling roll 207-3 to obtain a sheet-like biodegradable laminate according to the present invention. In the above-described manufacturing method, the first layer of the sheet (melt coextrusion molded product) in which the first, second, and third layers are integrated and extruded from the T-die is brought into contact with cooling roll 207-1 and cooling roll 207-2 to cool the first layer of the sheet, thereby allowing the first layer to be rapidly solidified. This prevents the sheet-like biodegradable laminate 100 from sticking to the surface of cooling roll 207-3, allowing the sheet-like biodegradable laminate 100 to be smoothly released from cooling roll 207-3. In other words, according to the above-mentioned method, the aliphatic polyester resin (a) according to the present invention exhibits excellent roll release properties, and a biodegradable laminate having an excellent surface can be obtained. In the above-mentioned extrusion molding method, the extrusion molding machine 201 is not particularly limited, but for example, a single-screw extruder, a twin-screw extruder, etc. can be used.The cylinder temperature of the extruder is not particularly limited as long as it is a temperature at which the resin or resin composition constituting the first to third layers can be melted and extruded. For example, the extruder cylinder temperature for the first layer is preferably 120 to 240°C, and particularly preferably 130 to 230°C. The extruder cylinder temperature for the second layer is preferably 160 to 240°C, and particularly preferably 180 to 230°C. The extruder cylinder temperature for the third layer is preferably 160 to 250°C, and particularly preferably 180 to 230°C. The screw rotation speed of each extruder is not particularly limited as long as it is appropriately set in relation to the screw diameter of each extruder, the width of the T-die, and the like so that the sheet is ultimately extruded from the T-die at the desired speed. For example, when the T-die width is 30 mm and the screw diameter of each extruder is 20 to 30 mm, a rotation speed of 30 to 70 rpm, and particularly 40 to 60 rpm, is preferred. Furthermore, the take-up speed by the cooling roll of the integrated sheet of the first to third layers extruded from the T-die, the surface temperature of the cooling roll, and the distance between the discharge opening of the T-die and the cooling roll may be appropriately set so that the thickness of each layer in the biodegradable laminate and / or the overall thickness of the biodegradable laminate are desired values, and are not particularly limited. For example, when a three-kind, five-layer film having layer thicknesses of 1st Layer / 2nd Layer / 3rd Layer / 2nd Layer / 1st Layer=30 μm / 10 μm / 20 μm / 10 μm / 30 μm and an overall thickness of 100 μm is obtained as the biodegradable laminate according to the present invention, it is preferable that the take-up speed is 1 to 100 m / min, particularly 3 to 50 m / min, and the surface temperature of the cooling roll is 10 to 50° C., particularly 15 to 40° C.

[0165] The biodegradable laminate of the present invention may be further subjected to a heat stretching treatment, which is expected to improve the strength and gas barrier properties. In particular, when a PVA-based resin having a 1,2-diol structure in the side chain is used as the PVA-based resin in the biodegradable laminate of the present invention, good stretchability is achieved.

[0166] For the stretching treatment, known stretching methods can be used, such as uniaxial stretching and biaxial stretching, in which both edges of the multilayer structure sheet are gripped and expanded; molding methods using a mold, such as deep drawing, vacuum forming, pressure forming, and vacuum pressure forming, in which the multilayer structure sheet is stretched using a mold; and methods in which a preformed multilayer structure such as a parison is processed by a tubular stretching method or a stretch-blow method.

[0167] As such a stretching method, when a film or sheet-like molded product is intended, it is preferable to employ a uniaxial stretching method or a biaxial stretching method.

[0168] In the case of a molding method such as deep drawing, vacuum forming, pressure forming, or vacuum pressure forming, it is preferable to uniformly heat the biodegradable laminate using a hot air oven, a heater oven, or a combination of both, and stretch it using a chuck, plug, vacuum force, compressed air force, or the like.

[0169] When a molded article such as a cup or a tray is intended in which the drawing ratio (depth of molded article (mm) / maximum diameter of molded article (mm)) is usually 0.1 to 3, it is preferable to employ a mold forming method in which a mold is used for stretching, such as deep drawing, vacuum forming, pressure forming, or vacuum pressure forming.

[0170] The biodegradable laminate of the present invention thus obtained has strong adhesive strength between both the aliphatic polyester resin layer and the adhesive layer, and between the PVA resin layer and the adhesive layer.

[0171] Hereinafter, specific embodiments of the present invention will be described in more detail using examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the present invention. The values ​​of various production conditions and evaluation results in the following examples have the meaning of preferred upper or lower limit values ​​in the embodiments of the present invention, and preferred ranges may be ranges defined by the above-mentioned upper or lower limit values ​​and the values ​​in the following examples or by combining the values ​​of the examples.

[0172] <Measurement of Melt Flow Rate (MFR) of Resin Used> Based on Japanese Industrial Standards (JIS) K7210-1 (2014), measurements were taken using a melt indexer at 190°C and a load of 2.16 kg. The unit is g / 10 min. However, for G-Polymer, measurements were taken at 210°C and a load of 2.16 kg.

[0173] <Melt Point Measurement> According to JIS K 7121 (2012), a differential scanning calorimeter (trade name: DSC8500, manufactured by PerkinElmer Japan) was used to measure a sample by heating it from 30°C to 200°C at a heating rate of 10°C / min, holding it at 200°C for 1 minute, then cooling it to 0°C at a cooling rate of 10°C / min, and then heating it again to 200°C at a heating rate of 10°C / min. The melting point was read from the peak top during the re-heating process of the thermogram.

[0174] [Raw Materials Used] The resins and other raw materials used in the Examples and Comparative Examples are as follows: "PBSSe" stands for "polybutylene succinate sebacate," "PBS" stands for "polybutylene succinate," "PBSA" stands for "polybutylene succinate adipate," "PLA" stands for "polylactic acid," "PBAT" stands for "polybutylene adipate terephthalate," and "PHBH" stands for "polyhydroxybutyrate hexanoate."

[0175] [Manufacturing Example] Preparation of Polycondensation Catalyst Solution 343.5 parts by weight of magnesium acetate tetrahydrate was placed in a reactor equipped with a stirrer, followed by 1,434 parts by weight of anhydrous ethanol (purity 99% by weight or higher). 218.3 parts by weight of ethyl acid phosphate (monoester:diester weight ratio 45:55) was then added, and the mixture was stirred at 23°C. After confirming complete dissolution of the magnesium acetate, 410.0 parts by weight of tetra-n-butyl titanate was added. Stirring was continued for an additional 10 minutes, yielding a homogeneous mixed solution. This mixed solution was concentrated under reduced pressure while maintaining a temperature below 60°C. Approximately half of the ethanol added was distilled off, leaving a translucent, viscous liquid. 1,108 parts by weight of 1,4-butanediol was added, and the mixture was further concentrated under reduced pressure while maintaining a temperature below 80°C, yielding a catalyst solution with a titanium atom content of 3.5% by weight.

[0176] Aliphatic Polyester Resin a-1: A reaction vessel equipped with a stirrer, a nitrogen inlet, a heater, a thermometer, and a pressure reducing port was charged with the following raw materials: 57.8 parts by weight of succinic acid, 12.3 parts by weight of sebacic acid, 64.4 parts by weight of 1,4-butanediol, and 0.125 parts by weight of trimethylolpropane. The molar ratio of succinic acid to sebacic acid was 89:11, and the proportion of the amount of 1,4-butanediol to the total amount of succinic acid and sebacic acid was 1.30.

[0177] While stirring the contents of the vessel, nitrogen gas was introduced into the vessel, and the system was immersed in a nitrogen atmosphere by vacuum substitution. Next, the raw materials were dissolved at 160°C. After confirming that the raw materials were completely dissolved and the distillation temperature had reached 50°C, the temperature was raised from 160 to 230°C over 1 hour while stirring the system, and the esterification reaction was continued at 230°C under normal pressure for 1 hour. Five minutes before the end of the esterification reaction, 0.60 parts by weight of a catalyst solution was added. After the esterification reaction, the temperature was raised from 230°C to 250°C over 30 minutes, and simultaneously, 0.07 x 10 ３ The pressure was reduced to a pressure of 100 Pa or less, and polymerization was continued while maintaining the heated and reduced pressure state. The polymerization was terminated when a predetermined viscosity was reached, thereby obtaining an aliphatic polyester resin a-1 (aliphatic polyester resin: diol unit amount 50 mol %, dicarboxylic acid unit amount 50 mol %, succinic acid unit amount based on total dicarboxylic acid unit amount: 89 mol %, sebacic acid unit amount: 11 mol %, MFR: 5.0 g / 10 min, melting point: 102°C).

[0178] Aliphatic Polyester Resin a-2 Aliphatic polyester resin a-2 (amount of diol units in the aliphatic polyester resin: 50 mol %, amount of dicarboxylic acid units: 50 mol %, amount of succinic acid units relative to total dicarboxylic acid units: 95 mol %, amount of sebacic acid units: 5 mol %, MFR: 5.0 g / 10 min, melting point: 108° C.) was produced in the same manner as in Production Example for Aliphatic Polyester Resin a-1, except that 62.8 parts by weight of succinic acid, 5.4 parts by weight of sebacic acid, 65.5 parts by weight of 1,4-butanediol, 0.125 parts by weight of trimethylolpropane, and 0.60 parts by weight of catalyst solution were used and the molar ratio of succinic acid to sebacic acid was changed to 95:5) was produced.

[0179] Aliphatic Polyester Resin a-3 Aliphatic polyester resin a-3 (amount of diol units in the aliphatic polyester resin: 50 mol%, amount of dicarboxylic acid units: 50 mol%, amount of succinic acid units in the total amount of dicarboxylic acid units: 80 mol%, amount of sebacic acid units: 20 mol%, MFR: 5.0 g / 10 min, melting point: 92°C) was produced in the same manner as in Production Example for Aliphatic Polyester Resin a-1, except that 50.0 parts by weight of succinic acid, 21.5 parts by weight of sebacic acid, 62.0 parts by weight of 1,4-butanediol, 0.125 parts by weight of trimethylolpropane, and 0.60 parts by weight of catalyst solution were used and the molar ratio of succinic acid to sebacic acid was changed to 80:20)

[0180] Aliphatic Polyester Resin a-4 Aliphatic polyester resin a-4 (amount of diol units in the aliphatic polyester resin: 50 mol %, amount of dicarboxylic acid units: 50 mol %, amount of succinic acid units relative to total dicarboxylic acid units: 74 mol %, amount of sebacic acid units: 26 mol %, MFR: 5.0 g / 10 min, melting point: 85° C.) was produced in the same manner as in Production Example for Aliphatic Polyester Resin a-1, except that 44.9 parts by weight of succinic acid, 27.1 parts by weight of sebacic acid, 60.2 parts by weight of 1,4-butanediol, 0.125 parts by weight of trimethylolpropane, and 0.60 parts by weight of catalyst solution were used, and the molar ratio of succinic acid to sebacic acid was changed to 74:26.

[0181] [Commercially available raw materials] <Other biodegradable resins (d)> PBS (trade name: BioPBS FZ91PM, manufactured by PTTMCC Biochem, MFR: 5.0 g / 10 min, melting point: 113°C) PBSA (trade name: BioPBS FD92PM, manufactured by PTTMCC Biochem, amount of succinic acid units in total dicarboxylic acid units: 74 mol%, MFR: 5.0 g / 10 min, melting point: 89°C) PHBH (trade name: Aonilex X131A, manufactured by Kaneka Corporation, 3HB / 3HH molar ratio: 94 / 6, MFR: 6.0 g / 10 min, melting point: 140°C) PLA (trade name: Ingeo 4032D, manufactured by NatureWorks, MFR: 3.5 g / 10 min, melting point: 170°C) PBAT (trade name: Ecoflex C1200, manufactured by BASF, MFR: 3.8 g / 10 min, melting point: 115°C)

[0182] <Inorganic filler> Talc (Micro Ace K-1, manufactured by Nippon Talc Co., Ltd., average particle size: 8 μm)

[0183] <Adhesive resin (b)> BTR (trade name: BTR8002P, manufactured by Mitsubishi Chemical Corporation, MFR: 1.1 g / 10 min, melting point: 115°C)

[0184] <Polyvinyl alcohol-based resin (c)> G-Polymer (trade name: Nichigo G-Polymer BVE8049P, manufactured by Mitsubishi Chemical Corporation, MFR: 4.0 g / 10 min, melting point: 185°C)

[0185] Examples 1-1 to 1-5, Comparative Examples 1-1 to 1-4 Manufacturing Method of Laminated Film The resins (compositions) for forming the first to third layers were dry-blended in the proportions shown in Table 1, and a three-kind, five-layer T-die molding machine (die width 350 mm, first layer extruder screw diameter 30 mm, second and third layer extruder screw diameters 20 mm) was used to produce a three-kind, five-layer laminate film consisting of first layer / second layer / third layer / second layer / first layer (first layer is the surface layer, second layer is the adhesive layer, and third layer is the intermediate layer (barrier layer)). The extrusion conditions were as follows: first layer extruder cylinder temperature 210°C, second and third layer extruder cylinder temperatures 240°C, and feed block and die section temperatures 240°C. The extruder rotation speed was 40 rpm for the first layer, 50 rpm for the second layer, and 60 rpm for the third layer. A semi-matt roll was used as the cooling roll, with a cooling roll temperature of 30°C and a cooling roll take-up speed of 5 m / min. The distance between the T-die outlet and the point where the sheet extruded from the T-die first contacted the cooling roller was 100 mm. The thickness of each layer of the film was adjusted to a total thickness of 100 μm, with a layer structure of 1st layer / 2nd layer / 3rd layer / 2nd layer / 1st layer = 30 μm / 10 μm / 20 μm / 10 μm / 30 μm. The laminated film was molded in an environment of 25°C. Regarding moldability during film production, the thermal stability and roll release properties of the molten film were evaluated using the following methods. The physical properties of the resulting laminated film were also evaluated using the following methods. The results are shown in Table 1.

[0186] <Thermal stability of the molten film> The state of the molten film was visually evaluated from the die exit. The evaluation criteria were as follows: Rank A (good): The molten film was transparent, semi-transparent, or milky white, and was in a normal state with no foreign matter, no significant filler agglomeration, and no air bubbles. There was also no resonance, making it excellent. Rank B (unacceptable): The molten film contained a lot of foreign matter or air bubbles, or the resonance was poor, making it unworkable.

[0187] <Release from Roll> The degree of adhesion to the chill roll when the laminate was released from the surface was observed. Under the same extrusion conditions, the take-up speed was gradually changed and the peeling sound and film properties were checked. The evaluation criteria were as follows: Rank A (good): When molded at a chill roll take-up speed of 5 m / min or more, the film peeled off from the chill roll without any peeling sound and the film surface was clean. Rank B (acceptable): When molded at a chill roll take-up speed of 5 m / min or more, there was a small peeling sound when the film peeled off from the chill roll, but the film surface was clean. Rank C (unacceptable): When molded at a chill roll take-up speed of 5 m / min or more, there was a loud peeling sound when the laminate peeled off from the chill roll and streaks appeared on the film surface. Or the laminate did not peel off from the chill roll, making operation impossible.

[0188] <Evaluation Method of Laminate Film> The obtained laminate film was evaluated for puncture impact strength, blocking test, adhesive strength, oxygen permeability, and biodegradation test using the following methods. The results are shown in Table 1. <Puncture Impact Strength (Impact Resistance)> Using a punching impact tester (manufactured by Toyo Seiki Seisakusho), a laminate film sample measuring 110 mm in width and 1300 mm in length was punched with an arm having a hemispherical tip with a diameter of 25 mm at 12 points to punch 50 mm diameter holes, and the puncture impact strength was measured and evaluated according to the following criteria. The higher the puncture impact strength, the more resistant the film to tearing, and therefore the better. Rank A (Good): Puncture impact strength is 2000 J / m or more. Rank B (Unacceptable): Puncture impact strength is less than 2000 J / m.

[0189] <Blocking test (blocking)> Five sheets of laminated film cut into 100 mm squares were stacked, sandwiched between press plates (weight 900 g), and placed in an oven at 80°C for 1 hour. The films were then removed and peeled one by one, and the state was evaluated based on the following criteria: Rank A (good): The films were not fused together and could be peeled off. Rank B (unacceptable): The films were fused together and deformed when peeled off, or could not be peeled off.

[0190] <Oxygen permeability> Based on JIS K7126 (2006), measurements were taken using an oxygen permeability measuring device (product name: OX-TRAN; manufactured by MOCON, USA) under conditions of a temperature of 23°C and a humidity of 65% RH, and the measured values ​​were evaluated based on the following criteria. The smaller the oxygen permeability, the higher the oxygen barrier property, which is preferable. Rank A (good): Oxygen permeability of 10 g / m ２ Rank B (unacceptable): Oxygen permeability is 10 g / m ２ ・day or more.

[0191] <Adhesive strength> The laminated sheet was cut into 15 mm wide strips, and the adhesive strength between one layer of layer a and four layers of c / b / c / a was measured using a T-peel test at a peel rate of 300 mm / min, and the measured values ​​were evaluated based on the following criteria. The higher the adhesive strength, the less likely interlayer peeling occurs, and therefore the better. Rank A (good): adhesive strength of 5 N or more. Rank B (unacceptable): adhesive strength less than 5 N.

[0192] <Biodegradation Test> [Soil Room Temperature Biodegradation Test (HC Biodegradability)] The laminate film to be evaluated was completely buried in soil (moisture content: 30%) collected from a farm in Mie Prefecture and stored at a temperature of 28±2°C for 3 months. The mass of the laminate film was then measured and the degree of decomposition was calculated. The calculated degree of decomposition was then evaluated for room temperature biodegradability in soil (HC biodegradability) based on the following criteria. The degree of decomposition was calculated using the following formula: Decomposition rate (%) = 100 - (sample weight after 3 months / sample weight before test) x 100 Rank A: Decomposition rate of 60% or more. Rank B: Decomposition rate of 40% or more but less than 60%. Rank C: Decomposition rate of less than 40%. [Seawater Biodegradation Test (Marine Decomposition)] The laminate film to be evaluated was completely immersed in seawater collected from Yokkaichi Port in Yokkaichi City, Mie Prefecture, and stored at a temperature of 28±2°C for 6 months. The mass of the laminate film was then measured and the degree of decomposition was calculated. The calculated decomposition rates were then evaluated for biodegradability in seawater (marine decomposition) according to the following criteria. The decomposition rate was calculated using the following formula: Decomposition rate (%) = 100 - (sample weight after 6 months / sample weight before test) x 100 Rank A: Decomposition rate of 60% or more. Rank B: Decomposition rate of 40% or more but less than 60%. Rank C: Decomposition rate of less than 40%. [Overall evaluation (judgment)] The evaluation results of the above soil room temperature biodegradation test (HC biodegradability) and seawater biodegradability test (marine decomposition) were evaluated for overall biodegradability according to the following criteria: Rank A (good): Good decomposition in both soil and seawater. Rank B (possible): Good decomposition in only one of soil or seawater. Rank C (unacceptable): Almost no decomposition in either soil or seawater.

[0193] [Examples 2-1 to 2-8, Comparative Examples 2-1 to 2-2] <Production of resin pellets for forming first layer> Aliphatic polyester resin (a), other biodegradable resin (d), and inorganic filler were blended in the proportions shown in Table 2, and kneaded using a twin-screw kneader (TEX30α manufactured by The Japan Steel Works, Ltd.) at a kneading temperature of 180°C, a screw rotation speed of 200 rpm, and a discharge rate of 20 kg / hour. The strand was passed through a water bath and pellets were obtained using a strand cutter. The obtained pellets were dried in a hot air dryer at 60°C for 5 hours.

[0194] <Method for manufacturing laminated film> The resins for each layer were dry-blended in the proportions shown in Table 2, and a three-kind, five-layer laminate film of first layer / second layer / third layer / second layer / first layer (A is the surface layer, B is the adhesive layer, and C is the intermediate layer (barrier layer)) was produced using a three-kind, five-layer T-die molding machine (die width 350 mm, first layer extruder screw diameter 30 mm, second and third layer extruder screw diameter 20 mm). The extrusion conditions were set to a first layer extruder cylinder temperature of 210°C, second and third layer extruder cylinder temperatures of 240°C, and feed block and die section temperatures of 240°C. The extruder rotation speed was set to 40 rpm for the first layer, 50 rpm for the second layer, and 60 rpm for the third layer. A semi-matt roll was used as the cooling roll, and the cooling roll temperature was 30°C and the cooling roll take-up speed was 5 m / min. The thickness of each layer of the film was adjusted to a total thickness of 100 μm, with a layer structure of 1st layer / 2nd layer / 3rd layer / 2nd layer / 1st layer = 30 μm / 10 μm / 20 μm / 10 μm / 30 μm. Regarding moldability during laminate film production, the thermal stability and roll release properties of the molten film were evaluated in the same manner as in Example 1-1. The physical properties (blocking and adhesive strength) and biodegradability of the resulting laminate film were also evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0195]

[0196]

[0197] Example 3-1 Manufacturing Method of Laminate Sheet Using aliphatic polyester resin a-1 for the first layer, BTR for the second layer, and G-Polymer for the third layer, a three-kind, five-layer laminate sheet of first layer / second layer / third layer / second layer / first layer (the first layer was a surface layer, the second layer was an adhesive layer, and the third layer was an intermediate layer (barrier layer)) was manufactured using the same multi-layer molding machine as in Example 1. The extrusion conditions were set to a first layer extruder cylinder temperature of 210°C, second layer and third layer extruder cylinder temperatures of 240°C, and feed block and die section temperatures of 240°C. The extruder rotation speed was set to 100 rpm for the first layer, 40 rpm for the second layer, and 40 rpm for the third layer. A semi-matt roll was used as a cooling roll, with a cooling roll temperature of 40°C and a cooling roll take-up speed of 1 m / min. The distance between the T-die outlet and the point where the sheet discharged from the T-die first contacted the cooling roller was 100 mm. In this way, the thickness of each layer of the sheet was adjusted to a total thickness of 1000 μm, with a layer structure of 1st layer / 2nd layer / 3rd layer / 2nd layer / 1st layer = 400 μm / 50 μm / 100 μm / 50 μm / 400 μm. The laminate sheet was molded in an environment of 25°C. The resulting multilayer sheet was then crushed using a sheet pelletizer to a size suitable for feeding into an extruder to obtain a recycled (regrind) raw material. The aliphatic polyester resin a-1 accounted for 80% by mass of the recycled raw material. A laminate sheet was manufactured using the same method as the sheet molding described above, except that this recycled raw material was used as the raw material for the first layer. Regarding the moldability during sheet production using the recycled raw material, the thermal stability and roll release properties of the molten film were evaluated using the following methods. The results are shown in Table 3.

[0198] <Thermal stability of the molten film> The state of the molten film was visually evaluated from the die exit. The evaluation criteria were as follows: Rank A (good): The molten film was transparent, semi-transparent, or milky white, and in a normal state with no fisheyes, aggregates, foreign matter, or ooze, and no bubbles. Rank B (unacceptable): The molten film was in a state where many fisheyes, aggregates, foreign matter, or ooze had occurred.

[0199] <Release from Roll> The degree of adhesion to the chill roll surface when the laminate was released from the roll was observed. Under the same extrusion conditions, the take-up speed was gradually changed to check the release properties and sheet properties. The evaluation criteria were as follows: Rank A (good): When molded at a chill roll take-up speed of 1 m / min or more, the center and edges of the sheet peeled off smoothly from the chill roll, and the sheet surface was clean. Rank B (acceptable): When molded at a chill roll take-up speed of 1 m / min or more, the edges of the sheet occasionally stuck to the chill roll when the center and edges peeled off from the chill roll, but the sheet surface was clean. Rank C (unacceptable): When molded at a chill roll take-up speed of 1 m / min or more, the edges of the sheet stuck to the chill roll when the center and edges peeled off from the chill roll, resulting in a roughened sheet surface. Or the laminate did not peel off from the chill roll, making the operation impossible.

[0200]

[0201] 100 and 100a: biodegradable laminate, 101 and 101a: outer layer, 102a: optional layer, 103 and 103a: adhesive layer, 105 and 105a: barrier layer, 107 and 107a: inner layer, 201: extruder, 203: feed block, 205: T-die, 207-1 to 207-3: cooling roll

Claims

1. A biodegradable laminate comprising, in this order, a first layer containing an aliphatic polyester resin, a second layer that is an adhesive layer, and a third layer containing a polyvinyl alcohol resin, wherein the first layer contains an aliphatic polyester resin (a), and the aliphatic polyester resin (a) has, as main structural units, a first repeating structural unit derived from an aliphatic diol and a second repeating structural unit derived from an aliphatic dicarboxylic acid, and the second repeating structural unit contains at least a repeating structural unit derived from succinic acid and a repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms.

2. The biodegradable laminate according to claim 1, wherein the content of the aliphatic polyester resin (a) in the first layer is 1% by mass or more and 100% by mass or less.

3. The biodegradable laminate according to claim 1, wherein the content of the aliphatic polyester resin (a) in the first layer is greater than 42% by mass and not more than 100% by mass.

4. A biodegradable laminate according to claim 1, wherein the content of the aliphatic polyester resin (a) in the first layer is 50% by mass or more and 100% by mass or less.

5. A biodegradable laminate according to claim 1, wherein the content of the repeating structural unit derived from succinic acid is 50 mol% or more and 99 mol% or less, based on the total number of moles of the second repeating structural unit.

6. A biodegradable laminate as described in claim 1, in which the content of repeating structural units derived from aliphatic dicarboxylic acids having 9 to 36 carbon atoms is 1 mol% or more and 50 mol% or less, based on the total number of moles of the second repeating structural units.

7. A biodegradable laminate according to claim 1, wherein the content of repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms is greater than 3 mol% and not more than 40 mol%, based on the total number of moles of the second repeating structural units.

8. A biodegradable laminate according to claim 1, in which the content of the repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms is 5 mol% or more and 35 mol% or less, based on the total number of moles of the second repeating structural units.

9. A biodegradable laminate according to claim 1, in which the content of repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms is 7 mol% or more and 35 mol% or less, based on the total number of moles of the second repeating structural units.

10. A biodegradable laminate according to claim 1, wherein the content of repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms relative to the repeating structural units derived from an aliphatic dicarboxylic acid in the aliphatic polyester resin (a) is 10 mol % or more and 30 mol % or less.

11. The biodegradable laminate according to claim 1, wherein the content of repeating structural units derived from an aliphatic dicarboxylic acid having 9 to 36 carbon atoms relative to the repeating structural units derived from an aliphatic dicarboxylic acid in the aliphatic polyester resin (a) is 11 mol % or more and 30 mol % or less.

12. A biodegradable laminate according to claim 1, wherein the aliphatic polyester resin (a) contains, as the repeating structural unit derived from the aliphatic dicarboxylic acid, a repeating structural unit derived from an aliphatic dicarboxylic acid having 9 to 13 carbon atoms.

13. The biodegradable laminate according to claim 1, wherein the aliphatic dicarboxylic acid having 9 to 36 carbon atoms is sebacic acid.

14. The biodegradable laminate according to claim 1, wherein the first layer further comprises a biodegradable polyester-based resin (d) different from the aliphatic polyester resin (a).

15. The biodegradable laminate according to claim 14, wherein the biodegradable polyester resin (d) has, as main structural units, a third repeating structural unit derived from an aliphatic diol and a fourth repeating structural unit derived from an aliphatic dicarboxylic acid, and the fourth repeating structural unit includes a repeating structural unit derived from succinic acid.

16. The biodegradable laminate according to claim 14, wherein the biodegradable polyester resin (d) contains a polyhydroxyalkanoate containing, as a main constituent unit, a constituent unit derived from 3-hydroxybutyrate.

17. A biodegradable laminate according to claim 14, wherein the mass ratio of the biodegradable polyester resin (d) to the aliphatic polyester resin (a) in the first layer is 0 mass % or more and 40 mass % or less.

18. The biodegradable laminate according to claim 1, wherein the first layer further comprises an inorganic filler (e).

19. The biodegradable laminate according to claim 14, wherein the first layer contains an inorganic filler (e), and the mass ratio of the inorganic filler (e) in the first layer to the total amount of the aliphatic polyester resin (a) and the aliphatic polyester-based resin (d) is 0 mass% or more and 50 mass% or less.

20. The biodegradable laminate according to claim 1, wherein the second layer comprises a modified polyester resin (F) obtained by graft-modifying a polyester resin with an α,β-unsaturated carboxylic acid and / or an anhydride thereof, and the polyester resin primarily contains at least one selected from the group consisting of aliphatic polyesters and aliphatic-aromatic polyester resins.

21. A packaging material comprising the biodegradable laminate according to any one of claims 1 to 20.

22. A coffee capsule, food container, or food packaging film comprising the biodegradable laminate according to any one of claims 1 to 20.

23. A method for producing a biodegradable laminate according to any one of claims 1 to 20, comprising the step of contacting the first layer of a melt co-extrusion molded product having the first layer, the second layer, and the third layer with a cooling member.

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