TW202513653A - β-Methyl-δ-valerolactone copolymer and resin composition - Google Patents

Abstract

A [beta]-methyl-[delta]-valerolactone copolymer is represented by general formulas (I) or (II).

Description

β-Methyl-δ-valerolactone copolymer and resin composition

The present invention relates to a β-methyl-δ-valerolactone copolymer and a resin composition containing the β-methyl-δ-valerolactone copolymer.

δ-Valerolactone polymers synthesized from δ-valerolactone are known as biodegradable materials. As environmental protection awareness increases, biodegradable materials are being used in a wide range of fields. Therefore, in order to give physical properties that are compatible with the use of biodegradable materials, improvements are being made to δ-valerolactone polymers.

For example, a technology related to (meth)acrylate is disclosed, and the (meth)acrylate is obtained by reacting (meth)acrylic acid, β-methyl-δ-valerolactone and a compound having one hydroxyl group in the molecule (Patent Document 1). Patent Document 1 states that the (meth)acrylate has a fast curing speed, and the film obtained by curing is soft and has a low glass transition point, and does not crystallize even below 0°C. Furthermore, Patent Document 1 also states that the resin composition containing the (meth)acrylate is suitable for coating optical glass fibers used for light transmission. Furthermore, an alkyl-δ-valerolactone polymer is disclosed, and the alkyl-δ-valerolactone polymer is obtained by reacting an alkyl-δ-valerolactone polymer containing a hydroxyl group with a cyclic ether (Patent Document 2). Patent document 2 states: The alkyl-δ-valerolactone polymer is a liquid derivative with relatively high thermal stability and can be used as a plasticizer. Furthermore, Reference Example 1 of Patent document 2 discloses a liquid β-methyl-δ-valerolactone polymer obtained by modifying both ends of poly(β-methyl-δ-valerolactone) diol with acetic anhydride. [Prior technical document] [Patent document]

Patent document 1: Japanese Patent Publication No. 1-258644 Patent document 2: Japanese Patent Publication No. 3-181516

[Problems to be solved by the invention]

As mentioned above, Patent Document 1 states that the film obtained by using the above-mentioned (meth)acrylate is soft and has a low glass transition point. However, when the above-mentioned (meth)acrylate is made into a resin composition mixed with a thermoplastic resin, the obtained resin composition has low plasticity. Furthermore, as in Patent Document 2, the polymer obtained by modifying the hydroxyl group at the end of poly(β-methyl-δ-valerolactone) diol as a plasticizer for thermoplastic resins still has room for improvement. Therefore, the subject of the present invention is to provide a β-methyl-δ-valerolactone copolymer that can impart good plasticity to the resin composition, and a resin composition with good plasticity and a manufacturing method. [Means for solving the problem]

The inventors of the present invention have repeatedly studied and found that the above-mentioned problem can be solved by using the β-methyl-δ-valerolactone copolymer and resin composition disclosed herein. That is, the present invention is as follows.

[1] A β-methyl-δ-valerolactone copolymer represented by the following general formula (I) or (II). [In the general formulae (I) and (II), R ¹ represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 14 carbon atoms. ^R2 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, a group represented by the following formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by the following formula (Y), a group in which one hydrogen atom bonded to at least one terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Y), or a group in which one hydrogen atom bonded to at least one carbon atom of a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Z). In the following formula (X), the bond represented by *1 is bonded to an oxygen atom. In the following formula (Y), the bond represented by *2 is bonded to the aforementioned linear alkyl group having 1 to 20 carbon atoms or the aforementioned branched alkyl group having 3 to 20 carbon atoms. In the following formula (Z), the bond represented by *3 is bonded to the aforementioned linear alkyl group having 1 to 20 carbon atoms or the aforementioned branched alkyl group having 3 to 20 carbon atoms. ^R3 represents a linear alkylene group having 2 to 20 carbon atoms or a branched alkylene group having 3 to 20 carbon atoms. A represents an oxygen atom, a sulfur atom, or an imino group. n is 2 to 1,000, m is 2 to 1,000, and p is 2 to 1,000. When there are multiple n, m, A, ^R1 , and ^R3 , they may be the same or different from each other. ] [2] The β-methyl-δ-valerolactone copolymer described in [1] above, wherein the above ^R1 is a linear alkylene group having 1 to 8 carbon atoms, a branched alkylene group having 3 to 8 carbon atoms, or an aryl group having 6 to 12 carbon atoms. [3] The β-methyl-δ-valerolactone copolymer according to [1] or [2], wherein ^R2 is a linear alkyl group having 1 to 8 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a group represented by the formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom of a linear alkyl group having 1 to 16 carbon atoms is substituted by a group represented by the formula (Y), or a group in which one hydrogen atom bonded to at least one carbon atom of a linear or branched alkyl group having 1 to 16 carbon atoms is substituted by a group represented by the formula (Z). [4] The β-methyl-δ-valerolactone copolymer according to any one of [1] to [3], wherein ^R3 is a linear alkylene group having 2 to 16 carbon atoms, or a branched alkylene group having 3 to 16 carbon atoms. [5] The β-methyl-δ-valerolactone copolymer according to any one of the above [1] to [4], wherein the number average molecular weight is 500 to 200,000. [6] The β-methyl-δ-valerolactone copolymer according to any one of the above [1] to [5], wherein in the above general formula (I), the content ratio of the block (E) represented by the following formula is 5 to 95% by mass. [7] A resin composition comprising the β-methyl-δ-valerolactone copolymer as described in any one of [1] to [6] and a thermoplastic resin. [8] The resin composition as described in [7], comprising 0.1 to 100 parts by mass of the β-methyl-δ-valerolactone copolymer per 100 parts by mass of the thermoplastic resin. [9] The resin composition as described in [7] or [8], wherein the thermoplastic resin comprises a polyester. [10] The resin composition as described in [7] or [8], wherein the thermoplastic resin comprises a biodegradable resin. [11] The resin composition as described in any one of [7] to [10] above, wherein the number average molecular weight of the resin composition is 1,000 to 1,000,000. [12] A shaped article comprising the resin composition as described in any one of [7] to [11] above. [13] A method for producing a β-methyl-δ-valerolactone copolymer, which is a method for producing a β-methyl-δ-valerolactone copolymer represented by the following general formula (I) or (II), comprising the following steps: a step (1) of reacting β-methyl-δ-valerolactone, an initiator, and a polymerization catalyst, and subjecting the β-methyl-δ-valerolactone to a ring-opening polymerization to obtain a reaction solution, and a step (2) of adding a terminal modification agent to the reaction solution to subject the terminal modification reaction to obtain the β-methyl-δ-valerolactone copolymer. [In the general formulae (I) and (II), R ¹ represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 14 carbon atoms. ^R2 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, a group represented by the following formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by the following formula (Y), a group in which one hydrogen atom bonded to at least one terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Y), or a group in which one hydrogen atom bonded to at least one carbon atom of a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Z). In the following formula (X), the bond represented by *1 is bonded to an oxygen atom. In the following formula (Y), the bond represented by *2 is bonded to the aforementioned linear alkyl group having 1 to 20 carbon atoms or the aforementioned branched alkyl group having 3 to 20 carbon atoms. In the following formula (Z), the bond represented by *3 is bonded to the aforementioned linear alkyl group having 1 to 20 carbon atoms or the aforementioned branched alkyl group having 3 to 20 carbon atoms. R ³ represents a linear alkylene group having 2 to 20 carbon atoms or a branched alkylene group having 3 to 20 carbon atoms. A represents an oxygen atom, a sulfur atom, or an imino group. n is 2 to 1,000, m is 2 to 1,000, and p is 2 to 1,000. When there are a plurality of n, m, A, p, R ¹ , R ² and R ³ , they may be the same or different from each other. ] [14] The method for producing a β-methyl-δ-valerolactone copolymer as described in [13] above, wherein the polymerization catalyst is an alkaline catalyst. [15] The method for producing a β-methyl-δ-valerolactone copolymer as described in [13] or [14] above, wherein the polymerization catalyst is butyl lithium. [16] The method for producing a β-methyl-δ-valerolactone copolymer as described in any one of the above [13] to [15], wherein the terminal modification agent is an acid anhydride or an acid halide. [17] The method for producing a β-methyl-δ-valerolactone copolymer as described in any one of the above [13] to [16], wherein the terminal modification agent is an acid anhydride. [18] The method for producing a β-methyl-δ-valerolactone copolymer as described in any one of the above [13] to [17], wherein in the above step (2), 1 to 20 molar equivalents of the terminal modification agent are added relative to the hydroxyl group of the above starting agent. [19] The method for producing a β-methyl-δ-valerolactone copolymer as described in any one of the above [13] to [18], wherein the number average molecular weight (Mn) is 500 to 200,000. [20] A method for producing a β-methyl-δ-valerolactone copolymer as described in any one of [13] to [19] above, wherein the initiator is a polyether having at least one hydroxyl group. [21] A method for producing a β-methyl-δ-valerolactone copolymer as described in any one of [13] to [20] above, wherein in the step (2), at least one selected from the group consisting of the β-methyl-δ-valerolactone, the initiator and the polymerization catalyst contained in the reaction solution is not removed, and the terminal modification agent is added to the reaction solution. [Effect of the Invention]

According to the present invention, a β-methyl-δ-valerolactone copolymer capable of imparting good plasticity to a resin composition, a resin composition having good plasticity and a manufacturing method thereof can be provided.

[Form used to implement the invention]

The following is an explanation based on an example of an implementation mode of the present invention (hereinafter sometimes referred to as "this implementation mode"). However, the implementation mode shown below is an example for concretizing the technical idea of the present invention, and the present invention is not limited to the following description. Furthermore, in this specification, the preferred form of the implementation mode is shown, but the combination of two or more preferred forms is also a preferred form. For matters expressed in numerical ranges, when there are several numerical ranges, the lower limit and upper limit values can be selectively combined as a preferred form. In addition, in this specification, when there is a description of a numerical range of "XX to YY", it means "above XX and below YY".

<β-methyl-δ-valerolactone copolymer> The β-methyl-δ-valerolactone copolymer of this embodiment is represented by the following general formula (I) or (II).

[R ¹ ] In the general formulae (I) and (II), R ¹ represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 14 carbon atoms.

Examples of the linear alkyl group having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridedecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosyl.

From the viewpoint of operability, the straight-chain alkyl group having 1 to 20 carbon atoms is preferably a straight-chain alkyl group having 1 to 16 carbon atoms, more preferably a straight-chain alkyl group having 1 to 10 carbon atoms, and further preferably a straight-chain alkyl group having 1 to 8 carbon atoms. Specifically, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-octyl and the like are preferred.

Examples of the branched alkyl group having 3 to 20 carbon atoms include isopropyl, 1-methylpropyl, 2-methylpropyl, tertiary butyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1,2-dimethylpropyl, 1-ethylpropyl, 2-ethylpropyl, 1,1-diethylpropyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,3,3-trimethylbutyl, 1-ethylbutyl, 1-ethylhexyl, 2-ethylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 5,5-dimethylhexyl, 1-ethylhexyl, 2-ethylhexyl, 3-ethylpentyl, 4-ethylpentyl, 1-propylpentyl, 2-propylpentyl, 1-butylpentyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 5,5-dimethylhexyl, 1-ethylhexyl, 2-ethylpentyl, 3-ethylpentyl, 4-ethylpentyl, 1-propylpentyl, 2-propylpentyl, 1-butylpentyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 5,5-dimethylhexyl, 1-ethylhexyl, 2 -ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 1-propylhexyl, 2-propylhexyl, 3-propylhexyl, 1-butylhexyl, 2-butylhexyl, 1-methylheptyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5-methylheptyl, 6-methylheptyl, 6,6-dimethylheptyl, 1-ethylheptyl, 2-ethylheptyl, 3-ethylheptyl, 4-ethylheptyl, 5-ethylheptyl, 1-propylheptyl, 2-propylheptyl, 3-propylheptyl, 1-methyl octyl, 2-methyloctyl, 3-methyloctyl, 4-methyloctyl, 5-methyloctyl, 6-methyloctyl, 7-methyloctyl, 7,7-dimethyloctyl, 1-ethyloctyl, 2-ethyloctyl, 3-ethyloctyl, 4-ethyloctyl, 5-ethyloctyl, 6-ethyloctyl, 1-methylnonyl, 2-methylnonyl, 3-methylnonyl, 4-methylnonyl, 5-methylnonyl, 6-methylnonyl, 7-methylnonyl, 8-methylnonyl, 3,5,5-trimethylhexyl and the like.

From the viewpoint of operability, the branched alkyl group having 3 to 20 carbon atoms is preferably a branched alkyl group having 3 to 16 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and further preferably a branched alkyl group having 3 to 8 carbon atoms. Specifically, isopropyl, 1-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 2-ethylhexyl, and the like are preferred.

As the aryl group having 6 to 14 carbon atoms, there can be mentioned: phenyl, 2-methylphenyl, 4-methylphenyl, 2,4-dimethylphenyl, 2-naphthyl, etc. The aryl group having 6 to 14 carbon atoms is preferably an aryl group having 6 to 12 carbon atoms, and more preferably a phenyl group. As the aralkyl group having 7 to 14 carbon atoms, there can be mentioned: phenylmethyl, phenylethyl, phenylpropyl, phenylbutyl, phenylpentyl, phenylhexyl, naphthylmethyl, naphthylethyl, etc. The aralkyl group having 7 to 14 carbon atoms is preferably an aralkyl group having 7 to 12 carbon atoms, and more preferably a phenylmethyl group.

From the viewpoint of operability, ^R1 is preferably a linear alkyl group having 1 to 8 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, and an aryl group having 6 to 12 carbon atoms, more preferably a linear alkyl group having 1 to 5 carbon atoms, and a branched alkyl group having 3 to 5 carbon atoms, and still more preferably a linear alkyl group having 1 to 3 carbon atoms.

[R ² ] In the general formulae (I) and (II), R ² represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, a group represented by the following formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by the following formula (Y), a group in which one hydrogen atom bonded to at least one terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Y), or a group in which one hydrogen atom bonded to at least one carbon atom of a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Z).

The "straight-chain alkyl group having 1 to 20 carbon atoms", "branched alkyl group having 3 to 20 carbon atoms", "aryl group having 6 to 14 carbon atoms", and "aralkyl group having 7 to 14 carbon atoms" ^represented by ^R2 can be exemplified in the same manner as the groups exemplified for the "straight-chain alkyl group having 1 to 20 carbon atoms", "branched alkyl group having 3 to 20 carbon atoms", "aryl group having 6 to 14 carbon atoms", and "aralkyl group having 7 to 14 carbon atoms" represented by R1 described above.

(Formula (X)) In formula (X), the bond represented by *1 is bonded to an oxygen atom. In addition, the oxygen atom is an oxygen atom bonded to ^R2 in the above general formula (I). ^R1 in the group represented by formula (X) has the same meaning as ^R1 described above. Furthermore, n in the group represented by formula (X) has the same meaning as n described below.

(Formula (Y)) In formula (Y), the bond represented by *2 is bonded to a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms. Specifically, it is bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms or a terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms. In addition, the linear alkyl group having 1 to 20 carbon atoms bonded to the bond represented by *2 is a linear alkyl group having 1 to 20 carbon atoms in a "group in which one hydrogen atom bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by formula (Y)". Furthermore, the branched alkyl group with 3 to 20 carbon atoms bonded to the bond shown in *2 is a branched alkyl group with 3 to 20 carbon atoms in "a group in which a hydrogen atom of at least one terminal carbon atom of the branched alkyl group with 3 to 20 carbon atoms is substituted by a group shown in formula (Y)".

^R1 in the group represented by formula (Y) has the same meaning as ^R1 described above. Furthermore, n and A in the group represented by formula (Y) have the same meaning as n and A described below. In the "group in which one hydrogen atom bonded to a terminal carbon atom in a linear alkyl group having 1 to 20 carbon atoms is substituted by a ^group represented by formula (Y)" represented by R2, the linear alkyl group having 1 to 20 carbon atoms can be exemplified in the same manner as the groups exemplified as the "linear alkyl group having 1 to 20 carbon atoms" represented by ^R1 described above. From the viewpoint of operability, the linear alkyl group having 1 to 20 carbon atoms is preferably a linear alkyl group having 1 to 16 carbon atoms, more preferably a linear alkyl group having 1 to 10 carbon atoms, and even more preferably a linear alkyl group having 1 to 5 carbon atoms.

In the "group in which one hydrogen atom bonded to at least one terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by formula (Y)" represented by ^R2 , the branched alkyl group having 3 to 20 carbon atoms can be exemplified in the same manner as the groups exemplified in the "branched alkyl group having 3 to 20 carbon atoms" represented by ^R1 above. From the viewpoint of operability, the branched alkyl group having 3 to 20 carbon atoms is preferably a branched alkyl group having 3 to 16 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and even more preferably a branched alkyl group having 3 to 5 carbon atoms.

(Formula (Z)) In formula (Z), the bond represented by *3 is bonded to a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms. Specifically, it is bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms and a terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms. In addition, the linear alkyl group having 1 to 20 carbon atoms or the branched alkyl group having 3 to 20 carbon atoms bonded to the bond represented by *3 is a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms in a "group in which one hydrogen atom bonded to at least one carbon atom in a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by formula (Z)".

^R1 in the group represented by formula (Z) has the same meaning as ^R1 described above. ^R3 , n, m and A in the group represented by formula (Z) have the same meaning as ^R3 , n, m and A described below. In the "group represented by ^R2 in which one hydrogen atom bonded to at least one carbon atom in a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by the group represented by formula (Z)", the linear alkyl group having 1 to 20 carbon atoms can be exemplified in the same manner as the groups exemplified in the "linear alkyl group having 1 to 20 carbon atoms" represented by ^R1 described above. From the viewpoint of operability, the straight-chain alkyl group having 1 to 20 carbon atoms is preferably a straight-chain alkyl group having 1 to 16 carbon atoms, more preferably a straight-chain alkyl group having 1 to 10 carbon atoms, and still more preferably a straight-chain alkyl group having 1 to 5 carbon atoms. In the "group in which ^one hydrogen atom bonded to at least one carbon atom in a straight-chain alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by formula (Z)" represented by R2, the branched alkyl group having 3 to 20 carbon atoms can be exemplified in the same manner as the groups exemplified as the "branched alkyl group having 3 to 20 carbon atoms" represented by ^R1 above. From the viewpoint of operability, the branched alkyl group having 3 to 20 carbon atoms is preferably a branched alkyl group having 3 to 16 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, and further preferably a branched alkyl group having 3 to 5 carbon atoms.

In the general formula (I), ^R2 is preferably a linear alkyl group having 1 to 8 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a group represented by the above formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom in a linear alkyl group having 1 to 16 carbon atoms is substituted by a group represented by the above formula (Y), and a group in which one hydrogen atom bonded to at least one carbon atom in a linear alkyl group having 1 to 16 carbon atoms or a branched alkyl group having 3 to 16 carbon atoms is substituted by a group represented by the above formula (Z), and more preferably a carbon atom a linear alkyl group having 1 to 5 carbon atoms, a branched alkyl group having 3 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a group represented by the above formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom in a linear alkyl group having 1 to 5 carbon atoms is substituted by a group represented by the above formula (Y), and one hydrogen atom bonded to at least one carbon atom in a linear alkyl group having 1 to 5 carbon atoms or a branched alkyl group having 3 to 5 carbon atoms is a group represented by the above formula (Z), and more preferably a linear alkyl group having 1 to 3 carbon atoms.

In the general formula (II), ^R2 is preferably a group represented by the above formula (X).

[R ³ ] In the general formulae (I) and (II), R ³ represents a linear alkylene group having 2 to 20 carbon atoms or a branched alkylene group having 3 to 20 carbon atoms.

Examples of the linear alkylene group having 2 to 20 carbon atoms or the branched alkylene group having 3 to 20 carbon atoms include ethylene (-(CH ₂ ) ₂ -), n-propylene (-(CH ₂ ) ₃ -), isopropylene (-CH ₂ -CH(CH ₃ )-), n-butylene (-(CH ₂ ) ₄ -), 1-methylpropylene (-CH ₂ -CH ₂ -CH(CH ₃ )-), 2-methylpropylene (-CH ₂ -CH(CH ₃ )-CH ₂ -), dimethylethylene (-CH ₂ -C(CH ₃ ) ₂ -), ethylethylene (-CH ₂ -CH(CH ₂ CH ₃ )-), n-pentylene (-(CH ₂ ) ₅ -), and 2-methylbutylene (-CH ₂ -CH ₂ -CH(CH ₃ )-CH ₂ -).

From the viewpoint of operability, ^R3 is preferably a linear alkylene group having 2 to 16 carbon atoms or a branched alkylene group having 3 to 16 carbon atoms, more preferably a linear alkylene group having 2 to 10 carbon atoms or a branched alkylene group having 3 to 10 carbon atoms, further preferably a linear alkylene group having 2 to 5 carbon atoms or a branched alkylene group having 3 to 5 carbon atoms, and further preferably a linear alkylene group having 2 to 5 carbon atoms.

[A] In general formulas (I) and (II), A represents an oxygen atom, a sulfur atom, or an imine group (-NH-). From the perspective of excellent biodegradability, A is preferably an oxygen atom.

[n, m, p] In general formula (I) and (II), n, m, and p represent the average number of repetitions. n is 2 to 1,000. In one embodiment of the present invention, n is preferably 2 to 800, more preferably 4 to 500, and further preferably 4 to 200. In other embodiments of the present invention, n is preferably 3 to 1,450, more preferably 3 to 250, further preferably 3 to 100, and further preferably 3 to 40. m is 2 to 1,000. In one embodiment of the present invention, m is preferably 2 to 400, more preferably 4 to 200, and further preferably 4 to 50. In other aspects of the present invention, m is preferably 3 to 1,450, more preferably 3 to 100, further preferably 3 to 50, further preferably 3 to 40. p is 2 to 1,000. In one aspect of the present invention, p is preferably 2 to 200, more preferably 4 to 100. In other aspects of the present invention, p is preferably 3 to 1,450, more preferably 3 to 200, further preferably 3 to 50.

m and n can be calculated from the ^1H -NMR spectrum of the β-methyl-δ-valerolactone copolymer. Specifically, when the aforementioned A is an oxygen atom, it can be calculated from the ^peak intensity of the hydrogen atom bonded to the carbon atom adjacent to the oxygen atom in the block (E) described later, and the peak intensity of the hydrogen atom bonded to the carbon atom adjacent to the oxygen atom of the ether bonded to the β-methyl-δ-valerolactone unit in the spectrum obtained by subjecting the β-methyl-δ-valerolactone copolymer to 1H-NMR measurement. The detailed calculation method of m and n can be according to the method described in the Examples. In addition, the so-called "β-methyl-δ-valerolactone unit" mentioned above means a structural unit derived from the β-methyl-δ-valerolactone unit, and means a unit repeated with an average repetition number n.

In the general formulae (I) and (II), when there are a plurality of n, m, A, p, R ¹ , R ² , and R ³ , they may be the same or different from each other.

[Examples of General Formula (I)] Here, in the general formula (I), R ² is exemplified as a structure in which R 2 represents a group represented by the above formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom in a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by the above formula (Y), a group in which one hydrogen atom bonded to at least one terminal carbon atom in a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the above formula (Y), or a group in which one hydrogen atom bonded to at least one carbon atom in a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the above formula (Z). In addition, the general formula (I) is not limited to these examples.

[Example 1] In the general formula (I), when R ² represents a group represented by the above formula (X), it is represented by the following general formula (Ia).

General formula (Ia)

[Example 2] In the general formula (I), when ^R2 represents a group in which a hydrogen atom bonded to a terminal carbon atom in a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by the above formula (Y), it is represented by the following general formula (Ib). In the general formula (Ib), R represents a linear alkylene group having 1 to 20 carbon atoms.

General formula (Ib)

[Example 3] In the general formula (I), ^R2 is a group in which a hydrogen atom bonded to at least one terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the above formula (Y), and when it represents a group in which a hydrogen atom bonded to all terminal carbon atoms of a 2-methylpropyl group is substituted by a group represented by the above formula (Y), it is represented by the following general formula (Ic).

General formula (Ic)

[Example 4] In the general formula (I), ^R2 is a group in which a hydrogen atom bonded to at least one carbon atom in a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is a group represented by the above formula (Z), and when it represents a group in which a hydrogen atom bonded to at least one carbon atom in an n-propyl group is substituted by a group represented by the above formula (Z), it is represented by the following general formula (Id).

General formula (Id)

[Example 5] In the general formula (I), ^R2 is a group in which a hydrogen atom bonded to at least one carbon atom in a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is a group represented by the above formula (Z), and when it represents a group in which a hydrogen atom bonded to at least one carbon atom in a 2-methylpropyl group is substituted by a group represented by the above formula (Z), it is represented by the following general formula (Ie).

General formula (Ie)

[Examples of Formula (II)] In the illustrated formula (II), R ² represents the structure of the group represented by the above formula (X). In addition, the formula (II) is not limited to the examples. <Example 6> In the formula (II), when R ² represents the group represented by the above formula (X), it is represented by the following formula (II-a).

General formula (II-a)

[Content ratio of block (E)] In general formula (I), the content ratio (mass %) of block (E) represented by the following formula is preferably 5 to 95 mass %. If the content ratio of block (E) is within the above numerical range, the β-methyl-δ-valerolactone copolymer can more reliably take into account the compatibility with thermoplastic resins and the plasticizing effect, and furthermore, it is preferred because the crystallization rate of the resin composition is further improved. Furthermore, the β-methyl-δ-valerolactone copolymer has a tendency to have higher compatibility with thermoplastic resins by having block (E) at a content ratio within the above numerical range, so it becomes easier to suppress bleeding. In one embodiment of the present invention, from the perspective of compatibility with thermoplastic resins and plasticizing effects, and from the perspective of improving the crystallization rate of the resin composition, the content ratio (mass %) of the block (E) represented by the following formula in the general formula (I) is preferably 5 to 50 mass%, and more preferably 10 to 40 mass%. In other embodiments of the present invention, from the perspective of compatibility with thermoplastic resins and plasticizing effects, and from the perspective of improving the crystallization rate of the resin composition, the content ratio (mass %) of the block (E) represented by the following formula in the general formula (I) is preferably 5 to 80 mass%, and more preferably 10 to 80 mass%, and more preferably 10 to 50 mass%.

Block (E)

The content ratio of block (E) is the ratio of the molecular weight of block (E) to the molecular weight of the β-methyl-δ-valerolactone copolymer. The content ratio of block (E) can be calculated from the molecular weight calculated by ¹ H-NMR measurement of the β-methyl-δ-valerolactone copolymer. Specifically, in the spectrum obtained by ¹ H-NMR measurement of the β-methyl-δ-valerolactone copolymer, the content ratio of block (E) can be calculated from the peak intensity of hydrogen atoms bonded to carbon atoms adjacent to oxygen atoms in block (E), the peak intensity of hydrogen atoms bonded to carbon atoms adjacent to oxygen atoms of ether bonded to β-methyl-δ-valerolactone units, and the peak intensity of hydrogen atoms bonded to carbon atoms at the α-position of the ester of β-methyl-δ-valerolactone units. The detailed measurement method of the content ratio of the block (E) can be based on the method described in the Examples.

<Weight average molecular weight of block (E)> In the β-methyl-δ-valerolactone copolymer represented by general formula (I), the weight average molecular weight of block (E) represented by the above formula is preferably 100 to 40,000, more preferably 100 to 10,000, further preferably 100 to 5,000, and further preferably 500 to 5,000 from the viewpoint of shortening the crystallization time. The weight average molecular weight of block (E) can be calculated from the following formula. The weight average molecular weight of block (E) in the β-methyl-δ-valerolactone copolymer represented by general formula (I) = weight average molecular weight Mw of β-methyl-δ-valerolactone copolymer × content ratio (mass %) of block (E) in general formula (I) / 100 In addition, the weight average molecular weight Mw of the β-methyl-δ-valerolactone copolymer is the weight average molecular weight converted to standard polystyrene obtained by gel permeation chromatography (GPC). The detailed measurement method can be described in the embodiment.

[Content ratio of block (F)] In general formula (II), the content ratio (mass %) of block (F) represented by the following formula is preferably 5 to 95 mass %. If the content ratio of block (F) is within the above numerical range, the β-methyl-δ-valerolactone copolymer can more reliably take into account the compatibility with thermoplastic resins and the plasticizing effect, and furthermore, it is preferred because the crystallization rate of the resin composition is further improved. Furthermore, since the β-methyl-δ-valerolactone copolymer has block (F) at the content ratio within the above numerical range, the compatibility with thermoplastic resins tends to be higher, so it becomes easy to suppress leakage.

Block (F)

The content ratio (mass %) of block (F) is the molecular weight of block (F) relative to the molecular weight of the β-methyl-δ-valerolactone copolymer. The content ratio of block (F) can be determined in the same manner as the above-mentioned block (E).

[Number average molecular weight (Mn)] The number average molecular weight of the β-methyl-δ-valerolactone copolymer is preferably 500 to 200,000, more preferably 500 to 110,000, further preferably 1,000 to 66,000, further preferably 1,000 to 33,000, further preferably 1,000 to 10,000, further preferably 1,000 to 6,000. If the number average molecular weight is within the above numerical range, the viscosity of the β-methyl-δ-valerolactone copolymer will not become too low, and the operability and productivity during molding will become good. The number average molecular weight of the β-methyl-δ-valerolactone copolymer is the number average molecular weight calculated by gel permeation chromatography (GPC) and determined in terms of standard polystyrene. The detailed measurement method can be based on the method described in the embodiment.

[Weight average molecular weight (Mw)] The weight average molecular weight of the β-methyl-δ-valerolactone copolymer is preferably 720 to 400,000, more preferably 720 to 220,000, further preferably 1,600 to 132,000, further preferably 1,600 to 66,000, further preferably 1,600 to 20,000, further preferably 1,600 to 12,000. If the weight average molecular weight is within the above numerical range, the viscosity of the β-methyl-δ-valerolactone copolymer will not become too low, and the operability and productivity during molding will become good. The weight average molecular weight of the β-methyl-δ-valerolactone copolymer is the number average molecular weight calculated by gel permeation chromatography (GPC) and determined in terms of standard polystyrene. The detailed measurement method can be based on the method described in the embodiment.

[Molecular weight distribution (Mw/Mn)] The molecular weight distribution (Mw/Mn) of the β-methyl-δ-valerolactone copolymer is preferably 1.0 to 3.0, more preferably 1.1 to 2.0, and further preferably 1.2 to 1.8. The molecular weight distribution of the β-methyl-δ-valerolactone copolymer is a value obtained from the number average molecular weight and weight average molecular weight calculated by gel permeation chromatography (GPC) in terms of standard polystyrene. The detailed method for measuring the number average molecular weight and the weight average molecular weight can be described in the examples.

[Viscosity] Depending on the application of the β-methyl-δ-valerolactone copolymer, the preferred viscosity range will vary. For example, from the perspective of operability, substrate retention, strength, and adhesion, and from the perspective of achieving a better modification effect on thermoplastic resins, the viscosity is preferably 500 to 600,000 mPa·s, more preferably 700 to 500,000 mPa·s, and further preferably 900 to 150,000 mPa·s at a measurement temperature of 30°C. From the same point of view, in other aspects of the present invention, at a measuring temperature of 30°C, it is preferably 600 to 550,000 mPa·s, more preferably 600 to 10,000 mPa·s, and further preferably 600 to 2,200 mPa·s. From the same point of view, in further other aspects of the present invention, at a measurement temperature of 60°C, it is preferably 5,000 to 600,000 mPa·s, more preferably 50,000 to 600,000 mPa·s, further preferably 100,000 to 400,000 mPa·s, further preferably 150,000 to 250,000 mPa·s, further preferably 170,000 to 220,000 mPa·s. The "viscosity" described in this specification is the viscosity of the β-methyl-δ-valerolactone copolymer measured by an E-type viscometer. The detailed measurement method can be described in the embodiment.

<Method for producing β-methyl-δ-valerolactone copolymer> The method for producing β-methyl-δ-valerolactone copolymer of the present embodiment is a method for producing β-methyl-δ-valerolactone copolymer represented by the following general formula (I) or (II). Then, it comprises: a step (1) of reacting β-methyl-δ-valerolactone, an initiator, and a polymerization catalyst, and performing a ring-opening polymerization on the β-methyl-δ-valerolactone to obtain a reaction solution, and a step (2) of adding a terminal modification agent to the reaction solution and performing a terminal modification reaction to obtain the copolymer.

In the general formulae (I) and (II), R ¹ represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 14 carbon atoms. ^R2 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, a group represented by the following formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by the following formula (Y), a group in which one hydrogen atom bonded to at least one terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Y), or a group in which one hydrogen atom bonded to at least one carbon atom of a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Z). In the following formula (X), the bond represented by *1 is bonded to an oxygen atom. In the following formula (Y), the bond represented by *2 is bonded to the aforementioned linear alkyl group having 1 to 20 carbon atoms or the aforementioned branched alkyl group having 3 to 20 carbon atoms. In the following formula (Z), the bond represented by *3 is bonded to the aforementioned linear alkyl group having 1 to 20 carbon atoms or the aforementioned branched alkyl group having 3 to 20 carbon atoms.

^R3 represents a linear alkylene group having 2 to 20 carbon atoms or a branched alkylene group having 3 to 20 carbon atoms. A represents an oxygen atom, a sulfur atom, or an imino group. n is 2 to 1,000, m is 2 to 1,000, and p is 2 to 1,000. When there are a plurality of n, m, A, p, ^R1 , ^R2 , and ^R3 , they may be the same or different from each other.

By comprising steps (1) and (2), a β-methyl-δ-valerolactone copolymer having good plasticity can be simply prepared.

[Step (1)] Step (1) is a step of reacting β-methyl-δ-valerolactone, an initiator, and a polymerization catalyst, and performing ring-opening polymerization on the β-methyl-δ-valerolactone to obtain a reaction solution. The reaction solution obtained in step (1) contains: a ring-opening polymer of β-methyl-δ-valerolactone, unreacted (not subjected to ring-opening polymerization) β-methyl-δ-valerolactone, unreacted initiator, and a polymerization catalyst. Step (1) is preferably performed under alkaline conditions.

(β-methyl-δ-valerolactone) β-methyl-δ-valerolactone can be produced by a known method. For example, it can be produced by a known method using 2-hydroxy-4-methyltetrahydropyran as a raw material (Japanese Patent Publication No. 6-53691, etc.). In addition, commercially available β-methyl-δ-valerolactone can be used, and it can be used regardless of whether it is derived from petrochemicals or from organisms. In step (1), 5 to 1,500 molar equivalents of β-methyl-δ-valerolactone are preferably added to the hydroxyl group of the starting agent, more preferably 5 to 1,200 molar equivalents, and even more preferably 10 to 600 molar equivalents.

(Initiator) As the initiator used in the present embodiment, alcohol is preferred, and polyether having at least one hydroxyl group is more preferred. From the viewpoint of obtaining a β-methyl-δ-valerolactone copolymer that can impart good plasticity, it is preferred that the carbon number in the structure of the repeating unit constituting the β-methyl-δ-valerolactone copolymer is preferably a polyether having a hydroxyl group of 2 to 20, more preferably 2 to 10, and further preferably 2 to 5. The polyether having a hydroxyl group may be linear or branched, but from the viewpoint of obtaining a β-methyl-δ-valerolactone copolymer that can impart good plasticity, a linear one is preferred. Examples of polyethers having a hydroxyl group include polyether monools and polyether polyols. Examples of polyether monools include polyoxyalkylene monol. Examples of polyether polyols include polymers obtained by using compounds having active hydrogen atoms as catalysts to perform ring-opening polymerization on cyclic ether compounds such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin, etc., either alone or in combination. Specifically, examples include polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene ether glycol (PTMG), polyhexamethylene ether glycol (PGL), etc. Among them, polyethylene glycol is preferred from the viewpoint of obtaining a β-methyl-δ-valerolactone copolymer that can impart good plasticity. In addition to the above, as initiators, for example, polyethers having at least one amine group and polyethers having at least one thiol group can be cited. As polyethers having at least one amine group, for example, triethylene glycolamine, diethylene glycol bis(3-aminopropyl) ether, poly(ethylene glycol) diamine, etc. can be cited. As polyethers having at least one thiol group, for example, poly(ethylene glycol) dithiol, etc. can be cited.

(Polymerization Catalyst) Step (1) is preferably carried out under alkaline conditions, and the polymerization catalyst that can be used in the present embodiment preferably has a catalytic effect under alkaline conditions. As the polymerization catalyst that has a catalytic effect under alkaline conditions, for example, an alkaline catalyst can be cited. The alkaline catalyst can use a known alkaline catalyst. As the above-mentioned alkaline catalyst, for example, metal catalysts such as alkali metals and alkali metal compounds, and organic alkali compounds can be cited. As the alkali metal compound, organic alkali metal compounds, alkali metal hydroxide compounds, and alkali metal hydroxide compounds can be cited, among which organic lithium compounds such as butyl lithium are also preferred. As the organic alkali compound, for example, an amine compound having an amidine skeleton or a guanidine skeleton can be cited. Furthermore, as the alkali catalyst, a metal catalyst such as an organic magnesium compound and an organic zinc compound can also be used. The polymerization catalyst can be used alone or in combination of two or more. When the alkali catalyst is used as the polymerization catalyst, it is preferred to add 0.005 to 1.5 molar equivalents of the alkali catalyst relative to the hydroxyl group of the initiator, more preferably 0.007 to 1.2 molar equivalents, further preferably 0.007 to 1.0 molar equivalents, further preferably 0.007 to 0.8 molar equivalents, further preferably 0.007 to 0.6 molar equivalents.

(Solvent) Step (1) can be carried out in the presence of a solvent that is inert to the ring-opening polymerization reaction. Examples of the solvent include: aliphatic hydrocarbons such as cyclohexane, methylcyclohexane, n-hexane, and n-pentane; and aromatic hydrocarbons such as benzene, toluene, and xylene. Among these, toluene is preferred from the viewpoint of solubility and stability (less possibility of reaction due to polymerization catalyst).

(Reaction conditions) In step (1), the method for mixing β-methyl-δ-valerolactone, the initiator, and the polymerization catalyst is not particularly limited, but from the perspective of operability, it is preferred to mix β-methyl-δ-valerolactone and the initiator, and after heating to the reaction temperature for reacting β-methyl-δ-valerolactone, the initiator, and the polymerization catalyst described below, add a solution containing a solvent inert to the ring-opening polymerization reaction and the polymerization catalyst dissolved in the solvent. By mixing in this way, the reaction state is stabilized, and the rapid reaction when the polymerization catalyst is added is suppressed, making it easy to obtain a β-methyl-δ-valerolactone copolymer with stable performance. The reaction temperature when β-methyl-δ-valerolactone, initiator, and polymerization catalyst react is preferably 20 to 100°C, more preferably 30 to 90°C, further preferably 30 to 80°C, and further preferably 40 to 80°C from the viewpoint of productivity. If it is within the above range, the reaction speed will be appropriate, and depolymerization can be suppressed, and the production efficiency will be good without reducing the raw material conversion rate. From the viewpoint of taking into account the consumption of β-methyl-δ-valerolactone and the production efficiency of β-methyl-δ-valerolactone copolymers, the reaction time is preferably 1 minute to 24 hours, more preferably 15 minutes to 12 hours, and further preferably 30 minutes to 6 hours. The reaction of β-methyl-δ-valerolactone, initiator, and polymerization catalyst is preferably carried out under an inert gas from the viewpoint of suppressing the deactivation of the polymerization catalyst. If carried out under an inert gas, the mixing of water is suppressed and the deactivation of the polymerization catalyst can be suppressed. As an inert gas, for example, nitrogen, helium, neon, argon, krypton, and carbon dioxide gas can be cited. From the viewpoint of higher availability and versatility, nitrogen is preferred.

[Step (2)] Step (2) is a step of adding a terminal modification agent to the aforementioned reaction solution to carry out a terminal modification reaction to obtain a β-methyl-δ-valerolactone copolymer. In step (2), it is preferred that the aforementioned terminal modification agent is added to the aforementioned reaction solution without removing at least one selected from the aforementioned β-methyl-δ-valerolactone, the aforementioned initiator and the aforementioned polymerization catalyst contained in the reaction solution obtained in step (1). That is, it is preferred that after the ring-opening polymerization of β-methyl-δ-valerolactone, at least one selected from the aforementioned β-methyl-δ-valerolactone, the aforementioned initiator, and the aforementioned polymerization catalyst is not taken out, or only the ring-opening polymer of β-methyl-δ-valerolactone is taken out and placed in another reaction container, and the terminal modification agent is not added to the reaction container, but the terminal modification agent is added to the reactor for the ring-opening polymerization, and the terminal modification of the ring-opening polymer of β-methyl-δ-valerolactone is performed. In this case, since the ring-opening polymerization reaction and the terminal modification reaction can be performed in one-pot, it can be manufactured in a simplified process.

(Terminal Modifier) As terminal modifiers that can be used in the present embodiment, acid anhydrides and acid halides can be cited. Among them, acid anhydrides are preferred from the viewpoint of reducing environmental load. As acid anhydrides and acid halides, for example, acid anhydrides and acid halides having at least one group selected from the group consisting of a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 14 carbon atoms can be used.

As the acid anhydride, specifically, acetic anhydride, oxalic anhydride, propionic anhydride, succinic anhydride, maleic anhydride, benzoic anhydride, phthalic anhydride, glutaric anhydride, methacrylic anhydride, butyric anhydride, isobutyric anhydride, 1,8-naphthalene dicarboxylic anhydride, trifluoroacetic anhydride, cyclohexanecarboxylic anhydride, etc. can be cited. Among them, acetic anhydride is preferred from the viewpoint of availability. As the acid halide, specifically, acetyl chloride, propionyl chloride, butyryl chloride, trifluoroacetyl chloride, benzyl chloride, 2-furoyl chloride (2-furoyl chloride), hexanoyl chloride, phenylacetyl chloride, acetyl bromide, propionyl bromide, benzyl bromide, etc. can be cited. Among them, acetyl chloride is preferred from the viewpoint of availability. In step (2), from the perspective of both reaction efficiency and production cost reduction, for the hydroxyl group of the initiator, it is preferred to add 1 to 20 molar equivalents of the terminal modifier, more preferably 1 to 10 molar equivalents, and further preferably 1 to 8 molar equivalents.

(Auxiliary catalyst) In step (2), an auxiliary catalyst may be added as needed. As the auxiliary catalyst, for example, amine compounds such as triethylamine, tributylamine, trioctylamine, imidazole, pyridine, aminopyridine, 4-dimethylaminopyridine, etc. may be used. Among them, 4-dimethylaminopyridine is preferred from the viewpoint of achieving high catalytic activity even in a small amount. In step (2), for the hydroxyl group of the initiator, it is preferred to add the auxiliary catalyst in an amount of 0.001 to 10 molar equivalents, more preferably 1 to 10 molar equivalents, and further preferably 1 to 8 equivalents.

[Step (3)] By going through the above steps (1) and (2), the β-methyl-δ-valerolactone copolymer represented by the above general formula (I) and (II) can be produced. If necessary, a step for isolating the produced β-methyl-δ-valerolactone copolymer, i.e., step (3), can also be performed. As step (3), an appropriate method can be adopted from known methods. For example, the reaction mixture containing the β-methyl-δ-valerolactone copolymer obtained in step (2) can be washed with a solvent and water, and then concentrated and purified by a method that can be used for separation and purification of ordinary organic compounds such as distillation. As a solvent, the (solvent) described in the above [step (1)] can be used.

In the method for producing the β-methyl-δ-valerolactone copolymer of the present embodiment, the details of R ¹ to R ³ , n, m, and p in the aforementioned general formulae (I) and (II), and R ¹ , R ³ , A, *1 to *3, n, and m in the aforementioned formula (X), the aforementioned formula (Y), and the aforementioned formula (Z), and preferred examples thereof are the same as those in the aforementioned "<β-methyl-δ-valerolactone copolymer>".

<Resin composition> The resin composition of this embodiment includes the above-mentioned β-methyl-δ-valerolactone copolymer and a thermoplastic resin.

[Thermoplastic resin] As the thermoplastic resin of this embodiment, polyester, biodegradable resins other than polyester, and general-purpose thermoplastic resins can be cited.

(Polyester) Thermoplastic resins may also contain polyester. Polyester includes non-biodegradable polyester and biodegradable polyester. Examples of polyesters include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polycyclohexane dimethyl terephthalate (PCT), polypropylene terephthalate (PTT), polyethylene adipate (TP26), polybutylene isophthalate (TP41), polyethylene terephthalate succinate (PETS), polyester composed of cyclohexanedimethanol and sebacic acid (TP CH10), copolyester composed of hexanediol, isophthalic acid and terephthalic acid (TP 6I/6T), copolyester composed of bisphenol A, isophthalic acid and terephthalic acid (TP BAI/BAT), copolyester composed of ethylene glycol, cyclohexanedimethanol and terephthalic acid (or its ester) (TP 2T/CHT), copolyester composed of ethylene glycol, terephthalic acid and isophthalic acid (or their esters) (TP 2T/2I), copolyester composed of ethylene glycol, 1,6-hexanediol and neopentyl glycol, terephthalic acid, isophthalic acid and adipic acid (TP 2/6/NG//T/I/6), copolyester composed of ethylene glycol and terephthalic acid and ethylene glycol and adipic acid (TP 2T/26), copolyester composed of neopentyl glycol and terephthalic acid, 1,6-hexanediol and isophthalic acid (TP NGT/6I), etc. Examples of polyester biodegradable resins include polylactic acid (PLA), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyglycolic acid (PGA), polyethylene furandicarboxylate (PEF), polyhydroxyalkanoate (PHA) [e.g. polyhydroxybutyrate (PHB), polyhydroxybutyrate hexanoate (PHBH), polyhydroxybutyrate valerate (PHBV), 3-hydroxybutyrate-3-hydroxyhexanoate copolymer polyester, etc.], starch polyester (Mater-Bi (registered trademark)), etc. Among them, polyester is preferably a biodegradable resin such as polylactic acid (PLA), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyglycolic acid (PGA), polyethylene furandicarboxylate (PEF), polyhydroxyalkanoate (PHA), etc. That is, the thermoplastic resin is preferably a biodegradable resin, and is preferably a polyester containing a biodegradable resin.

From the viewpoint of the required performance for flexibility, the thermoplastic resin is preferably a biodegradable resin, and the biodegradable resin is preferably a polylactic acid-based polymer.

(Polylactic acid polymer) In the present embodiment, the so-called polylactic acid polymer is a polymer having at least a structural unit derived from lactic acid. Examples of the polylactic acid polymer that can be used in the present embodiment include: at least one selected from the group consisting of a homopolymer of L-lactic acid, a homopolymer of D-lactic acid, a copolymer of L-lactic acid and D-lactic acid, and a cyclic dimer of lactic acid, i.e., a polymer of lactide. Furthermore, the polylactic acid polymer can also be a copolymer of lactic acid and at least one selected from the group consisting of aliphatic hydroxycarboxylic acids other than lactic acid, aliphatic dicarboxylic acids, aliphatic diols, and aromatic dicarboxylic acids. The above copolymer preferably contains structural units derived from lactic acid in an amount of preferably 70 mol% or more, more preferably 90 mol% or more. Among them, as the polylactic acid polymer, preferably a homopolymer of L-lactic acid, a homopolymer of D-lactic acid, or a copolymer of L-lactic acid and D-lactic acid, more preferably a homopolymer of L-lactic acid. In addition, when the polylactic acid polymer is a copolymer of L-lactic acid and D-lactic acid, the structural unit derived from L-lactic acid in the polylactic acid polymer is preferably 0.1 to 99.9 mass%, more preferably 1 to 99 mass%, and further preferably 2 to 98 mass%. The structural unit derived from D-lactic acid in the polylactic acid polymer is preferably 0.1 to 99.9 mass%, more preferably 1 to 99 mass%, and further preferably 2 to 98 mass%. The polylactic acid polymer may be used alone or in combination of two or more. Commercially available products may also be used as the polylactic acid polymer. Examples of commercially available products include: "INGEO series" manufactured by NatureWorks, "Luminy series" manufactured by TOTALENERGIES CORBION, "Revode" series manufactured by Zhejiang Hisun Biomaterials Co., Ltd, and "SUPLA" manufactured by SUPLA Material Technology Co., Ltd.

From the viewpoint of molding processability and compatibility with β-methyl-δ-valerolactone copolymer, the weight average molecular weight of polylactic acid polymer (PLA resin) is preferably 50,000-600,000, more preferably 100,000-400,000, and further preferably 150,000-300,000. If the weight average molecular weight of the polylactic acid resin is within the above numerical range, molding processability and compatibility with β-methyl-δ-valerolactone copolymer are good, which is preferred. The weight average molecular weight of the polylactic acid polymer (PLA resin) can be measured by gel permeation chromatography (GPC) and converted to standard polystyrene. In addition, when using commercial products, catalog values can also be used.

[Other thermoplastic resins] The thermoplastic resin may also contain other thermoplastic resins other than the above-mentioned polyester. Examples of other thermoplastic resins include biodegradable resins other than the above-mentioned biodegradable polyester resins and general-purpose thermoplastic resins.

Examples of biodegradable resins other than the above-mentioned polyester biodegradable resins include cellulose acetate (CA) and the like.

Examples of the general-purpose thermoplastic resin include thermoplastic resins and thermoplastic elastomers having a suitable processing temperature of 200°C or less. Examples of the thermoplastic resin include polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile-butadiene-styrene copolymer (ABS), and polycarbonate (PC). Examples of the thermoplastic elastomer include olefin-based, styrene-based, ester-based, urethane-based, acrylic-based, vinyl chloride-based, amide-based, and fluorine-based thermoplastic elastomers. Specific examples include polyester elastomer (TPC), thermoplastic polyurethane (TPU), and the like.

Furthermore, as the above-mentioned general-purpose thermoplastic resin, there can be cited: a thermoplastic resin having high heat resistance to a temperature exceeding 200°C (also referred to as a "high heat-resistant resin"). The above-mentioned so-called high heat-resistant resin is preferably a thermoplastic resin having a melting point exceeding 200°C. As the above-mentioned high heat-resistant resin, there can be cited, for example: polyamide (PA), polyacetal (POM), fluororesin [for example: polytetrafluoroethylene (PTFE), perfluoroalkoxy fluororesin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc.], polymethylpentene (PMP), etc.

The thermoplastic resin may be used alone or in combination of two or more. In addition, the thermoplastic resin contained in the resin composition of the present embodiment is not limited to the above-mentioned polyester, biodegradable resins other than the above-mentioned biodegradable resins which are polyesters, and general-purpose thermoplastic resins.

[Content ratio] In one embodiment of the present invention, from the viewpoint of plasticizing effect and suppression of exudation, the resin composition preferably contains 0.1 to 100 parts by mass of β-methyl-δ-valerolactone copolymer relative to 100 parts by mass of thermoplastic resin, more preferably 1 to 30 parts by mass, further preferably 1 to 15 parts by mass, and further preferably 1 to 10 parts by mass. In other aspects of the present invention, from the perspective of plasticizing effect and suppression of exudation, the resin composition preferably contains 1 to 30 parts by mass of β-methyl-δ-valerolactone copolymer relative to 100 parts by mass of thermoplastic resin, more preferably 2 to 20 parts by mass, further preferably 4 to 16 parts by mass, and further preferably 7 to 13 parts by mass.

The total content of the β-methyl-δ-valerolactone copolymer and the thermoplastic resin in the resin composition is preferably 80% by mass or more, more preferably 85% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, further preferably 98% by mass or more. Furthermore, the total content of the β-methyl-δ-valerolactone copolymer and the thermoplastic resin in the resin composition may be 100% by mass or less. If the content is the above, the effect of the present invention will be more significantly exerted.

The content ratio of block (E) in the β-methyl-δ-valerolactone copolymer represented by the above-mentioned general formula (I) in the resin composition of the present embodiment (the content ratio of block (E) in the resin composition) is preferably 0.3 to 10.0 mass%, more preferably 0.3 to 8.0 mass%, and further preferably 0.5 to 7.0 mass%. The content ratio of block (E) in the above-mentioned resin composition can be calculated from the following formula. Content ratio of block (E) in the resin composition (mass %) = content ratio of block (E) in general formula (I) (mass %) × content ratio of β-methyl-δ-valerolactone copolymer in the resin composition (mass %)/100

[Additives] The resin composition of this embodiment may contain additives in addition to the above-mentioned β-methyl-δ-valerolactone copolymer and thermoplastic resin. As additives, there can be cited: inorganic fillers, softeners, heat aging agents, antioxidants, hydrolysis inhibitors, light stabilizers, antistatic agents, release agents, flame retardants, foaming agents, pigments, dyes, whitening agents, ultraviolet absorbers, lubricants, etc. These may be used alone or in combination of two or more. When the above-mentioned additives are used, the content of the additives in the resin composition can be appropriately determined according to the desired physical properties of the resin composition.

[Number average molecular weight (Mn)] In one embodiment of the present invention, from the perspective of both tensile strength and formability, the number average molecular weight of the resin composition is preferably 1,000 to 1,000,000, more preferably 10,000 to 600,000, further preferably 30,000 to 500,000, further preferably 50,000 to 350,000, further preferably 60,000 to 250,000, further preferably 80,000 to 150,000. In other aspects of the present invention, from the same point of view, the number average molecular weight of the resin composition is preferably 500 to 300,000, more preferably 700 to 200,000, and further preferably 1,000 to 180,000. The number average molecular weight of the resin composition can be measured by gel permeation chromatography (GPC) and calculated by standard polystyrene conversion. Specifically, it is a value measured by the method described in the embodiment.

[Weight average molecular weight (Mw)] From the perspective of both tensile strength and formability, the weight average molecular weight of the resin composition is preferably 500 to 500,000, more preferably 700 to 300,000, and further preferably 1,000 to 250,000. The weight average molecular weight of the resin composition is the number average molecular weight converted to standard polystyrene determined by gel permeation chromatography (GPC). The detailed measurement method can be described in the embodiment.

[Glass transition temperature (Tg)] The β-methyl-δ-valerolactone copolymer of the present invention can lower the glass transition temperature of a thermoplastic resin. The glass transition temperature of a resin composition containing the β-methyl-δ-valerolactone copolymer of the present invention and a thermoplastic resin can be adjusted by the addition ratio of the aforementioned β-methyl-δ-valerolactone copolymer. The glass transition temperature of the resin composition is preferably reduced by 2°C or more, preferably by 70°C or less, more preferably by 65°C or less, and further preferably by 60°C or less, relative to the glass transition temperature of the thermoplastic resin, when the resin composition contains the β-methyl-δ-valerolactone copolymer in an amount of 1 to 100 parts by mass relative to 100 parts by mass of the thermoplastic resin. That is, it is preferably reduced by 2 to 70°C, more preferably by 2 to 65°C, and further preferably by 2 to 60°C. Because the glass transition temperature of the resin composition containing the β-methyl-δ-valerolactone copolymer of the present invention and the thermoplastic resin is lower than the glass transition temperature of the aforementioned thermoplastic resin, the plasticity and elongation of the aforementioned resin composition can be improved.

<Manufacturing method of resin composition> The manufacturing method of the resin composition of this embodiment is not particularly limited, and the β-methyl-δ-valerolactone copolymer, thermoplastic resin, and additives as required may be uniformly mixed. As the mixing method, there can be cited: a method of melt-kneading using a single-screw extruder, a multi-screw extruder, a Banbury mixer, a heating roll, a Brabender, various kneading machines, etc., or a method of supplying each component from a separate feed inlet and then melt-kneading, etc. Furthermore, pre-mixing may also be performed before melt-kneading. As a method for pre-mixing, there can be cited: a method using a mixer such as a Henschel mixer, a high-speed mixer, a V-type blender, a ribbon blender, a tumbler blender, or a cone blender. The temperature during melt mixing is selected in consideration of the melting point and decomposition temperature of the thermoplastic resin, and is preferably selected within the range of 140 to 220°C.

<Molded body> The molded body of this embodiment is a molded body comprising the above-mentioned resin composition. The shape of the above-mentioned molded body can be any molded body that can be produced using the resin composition of this embodiment. As molded bodies, there can be cited various shapes of molded bodies such as pellets, films, sheets, plates, pipes, tubes, bottles, fibers, rods, microparticles, particles, foams, etc. The manufacturing method of the molded body is not particularly limited, and it can be formed by various molding methods, such as injection molding, blow molding, press molding, extrusion molding, calendering, molding by a 3D printer, etc.

<Application> By preparing a resin composition in which the above-mentioned β-methyl-δ-valerolactone copolymer and a thermoplastic resin are mixed, the resin composition can have good plasticity. Therefore, the above-mentioned β-methyl-δ-valerolactone copolymer can be used as a modifier for thermoplastic resins.

The resin composition of this embodiment can be used for various purposes. Examples of the uses of the above-mentioned resin composition include: Food utensils such as food bags, food lids, food trays, straws, tableware (knives, forks and spoons), and food containers; Plugs and lid linings for containers for storing food, drinks, medicines, etc.; Single-layer or multi-layer films and sheets of electronic parts packaging materials, pharmaceutical packaging materials, food packaging materials, agricultural materials, civil engineering and construction materials, industrial materials, etc.; Fibers such as cloth and non-woven fabrics; Solvent-type, hot-melt-type, heat-stretch-type adhesives and bonding agents; Water-based, solution-type, emulsion-type, dispersion-type coating agents; 3D printer filaments; Toner for developing; Support materials for hydraulic fracturing and water loss-preventing agents for excavation; Various anti-vibration and vibration-damping components such as anti-vibration rubber, mats, sheets, buffers, damping, pads, and mounting rubber; Components such as frames of home appliances such as TVs, stereos, vacuum cleaners, and refrigerators, or mobile phone frames; Automobile interior and exterior decoration parts such as bumper parts, body panels, weather strips, grommets, instrument panels, and airbag covers; Various handles for scissors, screwdrivers, toothbrushes, ski poles, etc. [Examples]

Hereinafter, the present invention will be specifically described by way of embodiments and comparative examples, but the present invention is not limited thereto.

<Measurement and evaluation methods> Various physical properties are measured or evaluated using the following methods.

[Content ratio of block (E)] The content ratio (mass %) of block (E) in the β-methyl-δ-valerolactone copolymer is determined by ¹ H-NMR using the obtained β-methyl-δ-valerolactone copolymer (after hydroxyl end-capping) as a sample. The specific measurement method is as follows. (Measurement conditions) Apparatus: AVANCEIII400N (manufactured by Bruker Japan Co., Ltd.) Solvent: deuterated chloroform Measurement temperature: 23-25°C Cumulative number of times: 16 times Calculation method: Calculate the ¹ H-NMR spectrum obtained from the above measurement using the following method.

(Examples 1 to 9, 11, and 12, and Comparative Examples 2, 5, and 7) The obtained β-methyl-δ-valerolactone copolymer is a compound having a structure represented by the following formula (1) wherein R ³ in the above-mentioned general formula (I) is an ethylidene group (-(CH ₂ ) ₂ - ⁾ . In addition, in formula (1), * represents a bond. In the H-NMR spectrum, the sum of the peak intensity of the proton at the y position in formula (1) (3.6-3.8 ppm) and the peak intensity of the proton at the z position in formula (1) (3.6-3.7 ppm) multiplied by the molecular weight of the structural unit derived from β-methyl-δ-valerolactone (114.12) per unit is used to calculate the molecular weight of the structural unit derived from β-methyl-δ-valerolactone. The content ratio of block (E) in the β-methyl-δ-valerolactone copolymer is calculated by multiplying the sum of the molecular weight (114.12) of the structural unit of the ester per unit and the sum of the peak intensity (3.7-3.8 ppm) of the proton at the y position in the formula (1) and the peak intensity (3.6-3.8 ppm) of the proton at the z position in the formula (1) by the molecular weight (44.03) of the structural unit derived from ethylene glycol per unit. Specifically, it is calculated by the following formula. Content ratio of block (E) (mass %) = ((((peak intensity of protons derived from y position + peak intensity of protons derived from z position)/4) × molecular weight of structural unit derived from ethylene glycol per unit 44.03)/((((peak intensity of protons derived from y position + peak intensity of protons derived from z position)/4) × molecular weight of structural unit derived from ethylene glycol per unit 44.03) + ((peak intensity of protons derived from x position/2) × molecular weight of structural unit derived from β-methyl-δ-valerolactone per unit 114.12))) × 100

(Example 10 and Comparative Example 6) The β-methyl-δ-valerolactone copolymer obtained in Preparation Example 10 includes a compound represented by the following formula (2) in which R ³ in the aforementioned general formula (I) is an n-butyl group (-(CH ₂ ) ₄ -). Furthermore, the β-methyl-δ-valerolactone copolymer obtained in Comparative Preparation Example 6 also includes a compound represented by the following formula (2). In addition, in formula (2), * represents a bond. For the 1H-NMR spectrum obtained from the above measurement, the sum of the peak intensity of the proton at the v position in formula (2) (3.5-3.6 ppm) and the peak intensity of the proton at the w position in formula (2) (3.3-3.5 ppm) multiplied by the molecular weight of the structural unit derived from β-methyl-δ-valerolactone (114.12) per unit was used as the value, relative to the peak intensity of the proton at the u position in formula (2) (4.0-4.2 ppm) multiplied by the peak intensity of the proton at the β position in formula (2) (4.0-4.2 ppm) The content ratio of (E) in the β-methyl-δ-valerolactone copolymer is calculated by multiplying the sum of the molecular weight (114.12) of the structural unit of β-methyl-δ-valerolactone per unit, the peak intensity (3.5-3.6 ppm) derived from the proton at the v position in formula (2) and the peak intensity (3.3-3.5 ppm) derived from the proton at the w position in formula (2) by the sum of the molecular weight (72.11) of the structural unit derived from butanediol per unit. Specifically, it is calculated by the following formula. Content ratio of block (E) (mass %) = ((((peak intensity of protons derived from v position + peak intensity of protons derived from w position)/4) × molecular weight of structural unit derived from butanediol per unit 72.11)/((((peak intensity of protons derived from v position + peak intensity of protons derived from w position)/4) × molecular weight of structural unit derived from butanediol per unit 72.11) + ((peak intensity of protons derived from u position/2) × molecular weight of structural unit derived from β-methyl-δ-valerolactone per unit 114.12))) × 100

[m, n] (Examples 1 to 9, 11, and 12, and Comparative Examples 2, 5, and 7) m and n are calculated from the ¹ H-NMR spectrum measured when calculating the content ratio of the above block (E). m is calculated by adding 1 to the number obtained by dividing the number of protons at the z position in formula (1) (3.6-3.7 ppm) by the number of protons at the y position in formula (1) (3.7-3.8 ppm). n is calculated by subtracting the obtained content ratio of block (E) from 100, multiplying m and the molecular weight of block (E), and dividing the result by the molecular weight of the structural unit derived from β-methyl-δ-valerolactone per unit. Specifically, it is calculated by the following formula. In addition, the "y position" and "z position" in the following formula refer to the "y position" and "z position" in the above formula (1). m = ((the number of protons at the z position/4)/(the number of protons at the y position/2)) + 1 n = (m × molecular weight per unit of the structural unit derived from ethylene glycol 44.03 × (100 - the content ratio of block (E))/100) / molecular weight per unit of the structural unit derived from β-methyl-δ-valerolactone 114.12

(Example 10 and Comparative Example 6) m and n are calculated from the 1H-NMR spectrum measured when calculating the content ratio of the above block (E). m is calculated by adding 1 to the number obtained by dividing the number of protons at the w position in formula (2) (3.3-3.5ppm) by the number of protons at the v position in formula (2) (3.5-3.6ppm). n is calculated by multiplying the value obtained by subtracting the content ratio of the obtained block (E) from 100 by m and the molecular weight of the block (E), and dividing it by the molecular weight of the structural unit derived from β-methyl-δ-valerolactone per unit. Specifically, it is calculated by the following formula. In addition, "v position" and "w position" in the following formula mean "v position" and "w position" in the aforementioned formula (2). m=((number of protons at position w/4)/(number of protons at position v/2))+1 n=(m×molecular weight per unit of structural unit derived from butanediol 72.11×(100-content ratio of block (E))/100)/molecular weight per unit of structural unit derived from β-methyl-δ-valerolactone 114.12

(Comparative Examples 1, 3, and 4) n is calculated by adding 1 to the value obtained by dividing the number of protons at the t position in formula (3) (4.0-4.2ppm) by the number of protons at the s position in formula (3) (3.6-3.7ppm). Specifically, it is calculated by the following formula. In addition, "s position" and "t position" in the following formula mean "s position" and "t position" in the following formula (3). n = ((number of protons at the t position) / (number of protons at the s position)) + 1

[Number average molecular weight, weight average molecular weight, and molecular weight distribution of β-methyl-δ-valerolactone copolymers] The β-methyl-δ-valerolactone copolymers obtained in the examples and comparative examples were used as samples, and the number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) of the β-methyl-δ-valerolactone copolymers were determined by gel permeation chromatography (GPC) and standard polystyrene conversion molecular weight. The specific measurement method is as follows.

(When Mn is less than 15,000) For samples with Mn less than 15,000, Mn and Mw are determined as follows. A tetrahydrofuran (THF) solution is used as the eluent. 10 mg of the sample is measured in terms of resin and dissolved in 1 mL of the eluent. The solution is passed through a 0.2 μm membrane filter to prepare a measurement sample. The measurement conditions are set as follows. 〈Measurement conditions〉 GPC device: HLC-EcoSEC8320GPC (manufactured by Tosoh Co., Ltd.) Column: 3 columns of K-803 (manufactured by Resonac Co., Ltd.), K-802.5 (manufactured by Resonac Co., Ltd.), and K-802 (manufactured by Resonac Co., Ltd.) are connected in series. Eluent: tetrahydrofuran Flow rate: 0.9 mL/min Sample injection volume: 30 μL Column temperature: 40°C Standard polystyrene: PSt Oligomer Kit (molecular weight 589-98,900) manufactured by Tosoh Co., Ltd. was used and approximated by a cubic equation. Detector: RI detector Mw/Mn was calculated from the obtained Mn and Mw.

(When Mn is 15,000 or more) The sample with Mn of 15,000 or more is measured as follows to obtain Mn and Mw. A tetrahydrofuran solution is used as the eluent. 1.0 mg of the sample is measured in terms of resin and dissolved in 1 mL of the eluent. The solution is passed through a 0.2 μm membrane filter to prepare a measurement sample. The measurement conditions are set as follows. (Measurement conditions) GPC device: HLC-8220GPC (manufactured by Tosoh Corporation) Column: Two TSK-gel SuperHZM-M (manufactured by Tosoh Corporation) are connected in series. Eluent: tetrahydrofuran Flow rate: 0.35 mL/min Sample injection volume: 10 μL Column temperature: 40°C Standard polystyrene: Use polystyrene molecular weight standards (molecular weight 580-1,214,000) manufactured by GL Sciences Co., Ltd. and approximate with a cubic equation. Detector: RI detector Calculate Mw/Mn from the obtained Mn and Mw.

[Number average molecular weight of resin composition, weight average molecular weight of resin composition and polylactic acid polymer] The resin composition obtained in the examples and comparative examples was used as a sample, and the number average molecular weight (Mn) and weight average molecular weight (Mw) of the resin composition were calculated by gel permeation chromatography (GPC) and standard polystyrene conversion molecular weight. Furthermore, the weight average molecular weight (Mw) of polylactic acid polymer 1 was calculated by gel permeation chromatography (GPC) and standard polystyrene conversion molecular weight. The measurement conditions were set as follows. (Measurement conditions) GPC apparatus: High performance liquid chromatography LC-20A (manufactured by Shimadzu Corporation) Column: 3 columns of K-G 4A (manufactured by Resonac Co., Ltd.) (1 column) and K-806M (manufactured by Resonac Co., Ltd.) (2 columns) connected in series. Solvent: Chloroform Flow rate: 1.0 mL/min Sample injection volume: 100 μL Column temperature: 40°C Standard polystyrene: Agilent Technologies Co., Ltd. polystyrene standard (molecular weight: 2,880 to 6,570,000) was used and approximated with a fifth-order equation. Detector: RI detector

[Viscosity] The viscosity of the polymers obtained in the production examples and comparative production examples was measured in accordance with JIS K 7117-2:1999. Specifically, the viscosity (unit: mPa・s) of the β-methyl-δ-valerolactone copolymer was measured using an E-type viscometer (product name: TVE-25 type viscometer, manufactured by Toki Sangyo Co., Ltd.) at the measurement temperature shown in Table 2.

[Glass transition temperature (Tg) of resin composition] Using a differential scanning calorimeter ("DSC25" manufactured by TA Instrument), the resin composition obtained in the examples and comparative examples was heated from 30°C to 220°C at a rate of 10°C/min under a nitrogen flow rate (100 mL/min), maintained at 220°C for 5 minutes, and then cooled to -70°C at a rate of 10°C/min. The glass transition temperature was evaluated when the temperature was raised to 220°C at a rate of 10°C/min after being maintained at -70°C for 5 minutes.

[Crystallization time (crystallization rate)] Using a differential scanning calorimeter ("DSC25" manufactured by TA Instrument), the resin composition obtained in the examples and comparative examples was heated from 30°C to 220°C at a rate of 10°C/min under a nitrogen flow rate (100 mL/min), maintained at 220°C for 5 minutes, cooled to 95°C at a rate of 100°C/min, and the peak time of the crystallization peak when maintained at 95°C for 60 minutes was set as the crystallization time. It is known that the smaller the value, the faster the crystallization of the resin composition.

[Exudation Test] The resin composition obtained in the embodiment and comparative example was decompressed to -0.1 MPaG using a decompression hot press device ("IMC-183B" manufactured by Imoto Seisakusho Co., Ltd.) using an oil rotary pump, and preheated at 200°C for 5 minutes, and then pressed at 8 MPa for 3 minutes. Thereafter, a 0.5 mm thick press plate was produced by pressing at 8 MPa for 3 minutes using a cooling press device with water flow cooling. A 10 cm square test piece was punched from the obtained press plate. The surface condition of the obtained test piece stored at 80°C for more than 16 hours was evaluated visually and tactilely according to the following evaluation criteria. VG: No clear exudation or tackiness was observed. G: Although at least one of the groups consisting of slight exudation and tackiness was observed, it was a level that did not cause any problem in practical use. NG: At least one of the groups consisting of significant exudation and significant tackiness was observed, which was not suitable for practical use.

<Materials> The materials used in the embodiments and comparative examples are as follows.

[Initiator] ・CH ₃ -PEG200: Tetraethylene glycol monomethyl ether, manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Tetraethylene glycol monomethyl ether" (weight average molecular weight: 208.25) ・CH ₃ -PEG550: Polyethylene glycol monomethyl ether, manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Polyethylene glycol monomethyl ether 550" (weight average molecular weight (median value of catalog value): 550, weight average molecular weight (catalog value): 525~575))) ・CH ₃ -PEG1,000: Polyethylene glycol monomethyl ether, manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Polyethylene glycol monomethyl ether 1,000" (weight average molecular weight (median value of catalog value): 1,000, weight average molecular weight (catalog value) 950~1,050)) ・CH ₃ -PEG2,000: Polyethylene glycol monomethyl ether, manufactured by Tokyo Chemical Industry Co., Ltd., trade name "Polyethylene glycol monomethyl ether 2,000" (weight average molecular weight (median value of the catalog value): 2,000, weight average molecular weight (catalog value): 1,900 to 2,100)) ・PEG400: Polyethylene glycol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Polyethylene glycol 400" (weight average molecular weight (median value of the catalog value): 400, weight average molecular weight (catalog value): 360 to 440)) ・PEG1,000: Polyethylene glycol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Polyethylene glycol 1,000" (weight average molecular weight (median value of the catalog value): 1,000, weight average molecular weight (catalog value): 900 to 1,100))・PEG1,540: Polyethylene glycol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Polyethylene glycol 1,540" (weight average molecular weight (median value of the catalog value): 1,540, weight average molecular weight (catalog value): 1,350 to 1,650) ・PEG2,000: Polyethylene glycol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Polyethylene glycol 2,000" (weight average molecular weight (median value of the catalog value): 2,000, weight average molecular weight (catalog value): 1,800 to 2,200)・PEG20,000: Polyethylene glycol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Polyethylene glycol 20,000" (weight average molecular weight (mid-range of the catalog value): 20,000, weight average molecular weight (catalog value): 15,000 to 25,000)) ・PTMG1,000: Polytetramethylene ether glycol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Polytetramethylene oxide 1,000" (weight average molecular weight: 1,000 (mid-range of the catalog value, weight average molecular weight (catalog value): 950 to 1,100))

[Thermoplastic resin] ・Polylactic acid polymer 1: manufactured by NatureWorks, trade name "INGEO 2500HP" (weight average molecular weight: 200,000, melting point: 177°C, copolymer of L-lactic acid and D-lactic acid, content of structural units derived from L-lactic acid: 99% by mass) [Other drugs] ・n-Butyl lithium: manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., trade name "1.6 mol/L n-Butyl lithium hexane solution" ・Acetic anhydride: manufactured by Fuji Film Wako Pure Chemical Industries, Ltd. ・4-Dimethylaminopyridine: manufactured by Tokyo Chemical Industries, Ltd. ・Acrylic anhydride: manufactured by Tokyo Chemical Industries, Ltd. ・Ethylene glycol: manufactured by Tokyo Chemical Industries, Ltd. ・Toluene: manufactured by Kishida Chemical Co., Ltd. (special grade) ・Water: Ion-exchanged water (water obtained by exchanging ions with tap water using the "Pure Water Production Device Autostill WA500" (manufactured by Yamato Scientific Co., Ltd.)

[Production of β-methyl-δ-valerolactone] 5 g of copper chromium oxide catalyst (CuO-Cr ₂ O ₃ , "N203SD" manufactured by Nichiwa Catalyst Chemicals Co., Ltd.) was added to a 3 L four-necked flask, followed by 500 g of 2-hydroxy-4-methyltetrahydropyran (MHP) and 1 L of liquid paraffin, and stirred at a rotation speed of 350 rpm. It was heated with a mantle heater, and after the internal temperature reached 235°C, MHP was dripped continuously for 12 hours at a rate of 150 mL/30 minutes. 3.5 kg of β-methyl-δ-valerolactone was obtained from the solution distilled out from the distillation tube. It was confirmed that the obtained β-methyl-δ-valerolactone had a purity of more than 99%.

[Example 1] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 87.9 g of CH ₃ -PEG550 as an initiator and 268 g (2.351 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60° C. 2.6 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto and stirred at 60° C. for 60 minutes to obtain a reaction solution. Then, 19.6 g (192 mmol) of acetic anhydride as a terminal modification agent and 1.0 g (8.0 mmol) of 4-dimethylaminopyridine dissolved in 9.1 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 304 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition 100 parts by mass of polylactic acid polymer 1 and 10 parts by mass of the above-mentioned β-methyl-δ-valerolactone copolymer were put into a twin-shaft mixer ("ULTnano50" manufactured by Technovel), extruded into strands at a barrel temperature of 200°C, a screw speed of 50 rpm, and a retention time of 1 to 10 minutes. The obtained strands were cut into pellets to obtain a resin composition. The above-mentioned evaluation was performed on the obtained resin composition. The results are shown in Table 2.

[Example 2] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 37.7 g of CH ₃ -PEG200 as an initiator and 185 g (1.623 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60° C. 1.2 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto and stirred at 60° C. for 60 minutes to obtain a reaction solution. Then, 22.1 g (217 mmol) of acetic anhydride as a terminal modification agent and 1.11 g (9.1 mmol) of 4-dimethylaminopyridine dissolved in 10.3 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 185 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 3] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 74.5 g of CH ₃ -PEG1,000 as an initiator and 113 g (0.993 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 30° C. 2.1 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 30° C. for 60 minutes to obtain a reaction solution. Then, 9.2 g (90 mmol) of acetic anhydride as a terminal modification agent and 0.46 g (3.8 mmol) of 4-dimethylaminopyridine dissolved in 4.3 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 30°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 165 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 4] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 40.2 g of PEG400 as an initiator and 210 g (1.843 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60° C. 2.0 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60° C. for 60 minutes to obtain a reaction solution. Then, 24.9 g (244 mmol) of acetic anhydride as a terminal modifier and 1.23 g (10.1 mmol) of 4-dimethylaminopyridine dissolved in 11.9 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 212 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 5] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 103 g of PEG1,000 as an initiator and 150 g (1.313 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60° C. 1.3 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60° C. for 60 minutes to obtain a reaction solution. Then, 25.1 g (246 mmol) of acetic anhydride as a terminal modifier and 1.25 g (10.3 mmol) of 4-dimethylaminopyridine dissolved in 12.5 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 199 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 6] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 40.2 g of CH ₃ -PEG2,000 as an initiator and 208 g (1.818 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60° C. 1.8 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60° C. for 60 minutes to obtain a reaction solution. Then, 2.5 g (24.1 mmol) of acetic anhydride as a terminal modification agent and 0.25 g (2.0 mmol) of 4-dimethylaminopyridine dissolved in 2.5 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a vacuum dryer ("VACUUM OVEN VOS-450SD" manufactured by EYELA Tokyo Rika Instruments Co., Ltd.), thereby obtaining 202 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 7] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 14.2 g of CH ₃ -PEG2,000 as an initiator, 179 g (1.564 mol) of β-methyl-δ-valerolactone, and 73.3 g (796 mmol) of toluene were added and the temperature was raised to 30° C. 2.1 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 30° C. for 60 minutes to obtain a reaction solution. Then, 1.5 g (14.5 mmol) of acetic anhydride as a terminal modification agent and 0.04 g (0.35 mmol) of 4-dimethylaminopyridine dissolved in 0.43 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 30°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a vacuum dryer ("VACUUM OVEN VOS-450SD" manufactured by EYELA Tokyo Rika Instruments Co., Ltd.), thereby obtaining 166 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. The obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 8] (1) Preparation of β-methyl-δ-valerolactone copolymer A 1,000 mL glass 4-necked flask was substituted with nitrogen, and 63.4 g of PEG20,000 as an initiator, 150 g (1.316 mol) of β-methyl-δ-valerolactone, and 61.9 g (672 mmol) of toluene were added and heated to 30° C. 1.6 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 30° C. for 120 minutes to obtain a reaction solution. Then, 1.29 g (12.7 mmol) of acetic anhydride as a terminal modification agent and 0.04 g (0.32 mmol) of 4-dimethylaminopyridine dissolved in 0.36 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 30°C for 120 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a vacuum dryer ("VACUUM OVEN VOS-450SD" manufactured by EYELA Tokyo Rika Instruments Co., Ltd.), thereby obtaining 191 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. The obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 9] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 150 g of PEG1,540 as an initiator and 74.4 g (0.652 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 30° C. 1.8 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 30° C. for 60 minutes to obtain a reaction solution. Then, 23.9 g (234 mmol) of acetic anhydride as a terminal modification agent and 1.16 g (9.5 mmol) of 4-dimethylaminopyridine dissolved in 11.6 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 210 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 10] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 91.0 g of PTMG1,000 as an initiator and 102 g (0.896 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 30° C. 0.8 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 30° C. for 60 minutes to obtain a reaction solution. Then, 22.0 g (215 mmol) of acetic anhydride as a terminal modification agent and 1.10 g (8.98 mmol) of 4-dimethylaminopyridine dissolved in 10.7 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 30°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 178 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 11] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 87.9 g of CH ₃ -PEG550 as an initiator and 268 g (2.351 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60° C. 2.6 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60° C. for 60 minutes to obtain a reaction solution. Then, 30.4 g (192 mmol) of butyric anhydride as a terminal modification agent and 4-dimethylaminopyridine dissolved in 9.1 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 304 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Example 12] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 87.9 g of CH ₃ -PEG550 as an initiator and 268 g (2.351 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60° C. 2.6 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60° C. for 60 minutes to obtain a reaction solution. Then, 43.4 g (192 mmol) of benzoic anhydride as a terminal modifier and 4-dimethylaminopyridine dissolved in 9.1 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 304 g of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Comparative Example 1] (1) Preparation of β-methyl-δ-valerolactone polymer A 500 mL glass 4-necked flask was substituted with nitrogen, 5.6 g (90 mmol) of ethylene glycol as an initiator and 231 g (2.025 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60°C. 1.5 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60°C for 60 minutes to carry out a ring-opening polymerization reaction to obtain a reaction solution. The obtained reaction solution containing β-methyl-δ-valerolactone polymer was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 190 g of β-methyl-δ-valerolactone polymer. The above-mentioned measurements were performed on the physical properties of the obtained β-methyl-δ-valerolactone copolymer. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the following structural formula (A), and n is as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone polymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

Structural formula (A)

[Comparative Example 2] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 87.9 g of CH ₃ -PEG550 as an initiator and 268 g (2,351 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60°C. 2.6 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60°C for 60 minutes to obtain a reaction solution. Then, 24.1 g (192 mmol) of acrylic anhydride as a terminal modifier and 0.98 g (8.0 mmol) of 4-dimethylaminopyridine dissolved in 9.1 g of β-methyl-δ-valerolactone were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 304 g (0.19 mmol) of a β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. The obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone copolymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Comparative Example 3] (1) Preparation of β-methyl-δ-valerolactone polymer A 500 mL glass 4-necked flask was substituted with nitrogen, 1.1 g (17.7 mmol) of ethylene glycol as an initiator and 229 g (2,007 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60°C. 1.5 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60°C for 60 minutes to carry out a ring-opening polymerization reaction and obtain a reaction solution. The obtained reaction solution containing β-methyl-δ-valerolactone polymer was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 159 g of β-methyl-δ-valerolactone polymer. The above-mentioned measurements were performed on the physical properties of the obtained β-methyl-δ-valerolactone copolymer. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is shown in the above-mentioned structural formula (A), and n is shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone polymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Comparative Example 4] (1) Preparation of β-methyl-δ-valerolactone polymer A 4-necked glass flask with a content of 1,000 mL was substituted with nitrogen, and 1.2 g (19.3 mmol) of ethylene glycol as an initiator, 625 g (5.476 mol) of β-methyl-δ-valerolactone, and 258 g (2.796 mol) of toluene were added and heated to 30°C. 4.1 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 30°C for 60 minutes to carry out a ring-opening polymerization reaction, and a reaction solution was obtained. The obtained reaction solution containing the polymer was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 532 g of β-methyl-δ-valerolactone polymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is shown in the above structural formula (A), and n is shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone polymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Comparative Example 5] (1) Preparation of β-methyl-δ-valerolactone polymer A 500 mL glass 4-necked flask was substituted with nitrogen, 5.6 g (90 mmol) of ethylene glycol as an initiator and 231 g (2.025 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60°C. 0.79 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60°C for 60 minutes to obtain a reaction solution. Then, 22.1 g (216 mmol) of acetic anhydride as a terminal modification agent and 1.1 g (9.0 mmol) of 4-dimethylaminopyridine were placed in the reaction solution in the above-mentioned glass 4-necked flask, and stirred at 60°C for 60 minutes to obtain a reaction solution containing a β-methyl-δ-valerolactone copolymer. The above-mentioned reaction solution was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 158 g of β-methyl-δ-valerolactone polymer. The above-mentioned measurements were performed on the physical properties of the obtained β-methyl-δ-valerolactone copolymer. The results are shown in Table 2. Furthermore, the obtained β-methyl-δ-valerolactone copolymer is represented by the aforementioned general formula (I), and R ¹ , R ² , R ³ , m, n, and A are as shown in Table 1.

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone polymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Comparative Example 6] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 91.0 g of PTMG1,000 as an initiator and 102 g (0.896 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 30°C. 0.8 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 30°C for 60 minutes to obtain a reaction solution. The obtained reaction solution containing the polymer was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 170 g of β-methyl-δ-valerolactone copolymer. The above-mentioned measurements were performed on the physical properties of the obtained β-methyl-δ-valerolactone copolymer. The results are shown in Table 2. The obtained β-methyl-δ-valerolactone copolymer is represented by the following structural formula (B), and m and n are shown in Table 1. Structural formula (B)

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone polymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Comparative Example 7] (1) Preparation of β-methyl-δ-valerolactone copolymer A 500 mL glass 4-necked flask was substituted with nitrogen, 87.9 g of CH ₃ -PEG550 as an initiator and 268 g (2.351 mol) of β-methyl-δ-valerolactone were added and the temperature was raised to 60°C. 2.6 mL of n-butyl lithium (1.6 M hexane solution) as a polymerization catalyst was added thereto, and the mixture was stirred at 60°C for 60 minutes to obtain a reaction solution. The obtained reaction solution containing the polymer was extracted with toluene and water, and the volatile components were distilled off using a thin film evaporator ("Molecular Distillation Apparatus MS-300" manufactured by Shibata Scientific Co., Ltd.), thereby obtaining 300 g of β-methyl-δ-valerolactone copolymer. The physical properties of the obtained β-methyl-δ-valerolactone copolymer were measured as described above. The results are shown in Table 2. The obtained β-methyl-δ-valerolactone copolymer is represented by the following structural formula (C), and m and n are shown in Table 1. Structural formula (C)

(2) Preparation of resin composition A resin composition was obtained by the same method as in Example 1 except that the obtained β-methyl-δ-valerolactone polymer was used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[Reference Example 1] For reference, the glass transition temperature and crystallization time of the above-mentioned polylactic acid polymer 1 are shown in Table 2.

[Table 1] R ¹ R ² R ³ m n A n in formula (X) Content ratio of block (E) Embodiment 1 CH ₃ CH _{3 CH2CH2 ​} 8 10 Oxygen Atom - 23% mass Embodiment 2 CH ₃ CH _{3 CH2CH2 ​} 6 18 Oxygen Atom - 11% by mass Embodiment 3 CH ₃ CH _{3 CH2CH2 ​} 15 9 Oxygen Atom - 38% quality Embodiment 4 CH ₃ (X) _{CH2CH2 ​} 6 6 Oxygen Atom 6 16% by mass Embodiment 5 CH ₃ (X) _{CH2CH2 ​} 17 4 Oxygen Atom 4 47% quality Embodiment 6 CH ₃ CH _{3 CH2CH2 ​} 45 75 Oxygen Atom - 19% mass Embodiment 7 CH ₃ CH _{3 CH2CH2 ​} 41 97 Oxygen Atom - 8% quality Embodiment 8 CH ₃ (X) _{CH2CH2 ​} 477 195 Oxygen Atom 195 32% quality Embodiment 9 CH ₃ (X) _{CH2CH2 ​} 34 2 Oxygen Atom 2 77% quality Embodiment 10 CH ₃ (X) CH ₂ CH ₂ CH ₂ CH ₂ 15 6 Oxygen Atom 6 44% quality Embodiment 11 Positive Pr CH _{3 CH2CH2 ​} 8 10 Oxygen Atom - 23% mass Embodiment 12 Ph CH _{3 CH2CH2 ​} 8 10 Oxygen Atom - 23% mass Comparison Example 1 Structural formula (A) - 11 - - - Comparison Example 2 CH= _CH2 CH _{3 CH2CH2 ​} 7 11 Oxygen Atom - 22% mass Comparison Example 3 Structural formula (A) - 42 - - - Comparison Example 4 Structural formula (A) - 105 - - - Comparison Example 5 CH ₃ (X) _{CH2CH2 ​} 1 13 Oxygen Atom 13 4% quality Comparison Example 6 Structural formula (B) 15 6 - - 44% quality Comparative Example 7 Structural formula (C) 8 10 - - 23% mass Reference Example 1 Polylactic acid polymer 1

[Table 2] β-Methyl-δ-valerolactone copolymer Resin composition Number average molecular weight Weight average molecular weight Molecular weight distribution Viscosity (mPa・s) Viscosity measurement temperature (℃) Modifier addition amount (weight) ^*1 Number average molecular weight Weight average molecular weight Block (E) content (mass %) Resin composition Tg (℃) Crystallization time (min) Permeation test Embodiment 1 3,100 5,000 1.6 1,600 30 10 104,100 161,400 2.1 47 4 VG Embodiment 2 2,100 3,400 1.6 1,000 30 10 130,200 196,200 1.0 49 6 VG Embodiment 3 3,900 4,700 1.2 1,200 30 10 104,700 177,000 3.5 46 2 VG Embodiment 4 3,200 4,800 1.5 1,800 30 10 100,300 164,400 1.5 47 4 VG Embodiment 5 3,600 4,200 1.2 900 30 10 106,500 177,800 4.3 45 2 VG Embodiment 6 10,600 17,000 1.6 545,900 30 10 110,800 173,400 1.7 56 2 VG Embodiment 7 24,000 40,200 1.7 193,000 60 10 131,400 185,600 0.7 57 3 VG Embodiment 8 65,600 111,700 1.7 Unable to determine 80 10 137,000 192,300 2.9 59 7 VG Embodiment 9 3,200 5,300 1.7 600 30 10 109,700 176,000 7.0 43 2 VG Embodiment 10 3,600 4,700 1.3 1,400 30 10 109,200 174,800 4.0 53 2 VG Embodiment 11 3,000 5,000 1.7 1,600 30 10 101,500 163,400 2.1 49 4 VG Embodiment 12 3,100 5,000 1.6 1,500 30 10 102,600 166,600 2.1 49 4 VG Comparison Example 1 3,500 5,200 1.5 5,100 30 10 112,100 175,000 - 53 8 VG Comparison Example 2 3,200 5,100 1.6 1,700 30 10 127,400 187,400 2.0 61 9 VG Comparison Example 3 9,700 16,500 1.7 38,300 60 10 121,100 180,100 - 60 7 G Comparison Example 4 24,700 41,000 1.7 122,500 80 10 130,100 189,400 - 61 7 NG Comparison Example 5 4,200 6,500 1.5 5,700 30 10 99,100 180,800 0.4 53 7 VG Comparative Example 6 3,700 4,700 1.3 1,500 30 10 62,200 111,200 2.1 50 3 NG Comparative Example 7 2,900 4,800 1.7 1,700 30 10 60,900 108,200 2.1 44 5 NG Reference Example 1 - - - - - - 83,300 166,000 - 61 10 - *1: Indicates the amount of modifier added relative to 100 parts by mass of polylactic acid.

The symbols in Table 1 are as follows: ・In the column of R ² , "(X)" represents the aforementioned formula (X).

Comparing Examples 1 to 12 with the reference examples, it can be seen that the β-methyl-δ-valerolactone copolymer represented by the general formula (I) or (II) above significantly lowers the glass transition temperature of the thermoplastic resin, thereby imparting good plasticity to the thermoplastic resin. Furthermore, comparing Examples 1, 3 to 5, 9, and 10 with Comparative Examples 1 and 2, it can be seen that although the weight average molecular weight of the polymers is the same, the β-methyl-δ-valerolactone copolymer of the present embodiment significantly lowers the glass transition temperature of the thermoplastic resin, thereby imparting good plasticity to the thermoplastic resin. Similarly, from the comparison between Example 6 and Comparative Example 3, and Example 7 and Comparative Example 4, it can be seen that although the weight average molecular weight of the polymers is the same, the β-methyl-δ-valerolactone copolymer of this embodiment significantly reduces the glass transition temperature of the thermoplastic resin, thereby imparting good plasticity to the thermoplastic resin.

without

without.

without.

Claims (21)

A β-methyl-δ-valerolactone copolymer represented by the following general formula (I) or (II): [In the general formulae (I) and (II), ^R1 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 14 carbon atoms; R ² represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, a group represented by the following formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by the following formula (Y), a group in which one hydrogen atom bonded to at least one terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Y), or a group in which one hydrogen atom bonded to at least one carbon atom of a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Z); In the following formula (X), the bond represented by *1 is bonded to an oxygen atom; in the following formula (Y), the bond represented by *2 is bonded to the linear alkyl group having 1 to 20 carbon atoms or the branched alkyl group having 3 to 20 carbon atoms; in the following formula (Z), the bond represented by *3 is bonded to the linear alkyl group having 1 to 20 carbon atoms or the branched alkyl group having 3 to 20 carbon atoms; ^R3 represents a linear alkylene group having 2 to 20 carbon atoms or a branched alkylene group having 3 to 20 carbon atoms; A represents an oxygen atom, a sulfur atom, or an imino group; n is 2 to 1,000, m is 2 to 1,000, and p is 2 to 1,000; when there are multiple n, m, A, ^R1 and ^R3 , they may be the same or different from each other]. The β-methyl-δ-valerolactone copolymer of claim 1, wherein R ¹ is a linear alkyl group having 1 to 8 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, or an aryl group having 6 to 12 carbon atoms. The β-methyl-δ-valerolactone copolymer of claim 1 or 2, wherein ^R2 is a linear alkyl group having 1 to 8 carbon atoms, a branched alkyl group having 3 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a group represented by the formula (X), a group in which a hydrogen atom bonded to a terminal carbon atom in a linear alkyl group having 1 to 16 carbon atoms is substituted by a group represented by the formula (Y), or a group in which a hydrogen atom bonded to at least one carbon atom in a linear or branched alkyl group having 1 to 16 carbon atoms is substituted by a group represented by the formula (Z). The β-methyl-δ-valerolactone copolymer according to any one of claims 1 to 3, wherein R ³ is a linear alkyl group having 2 to 16 carbon atoms or a branched alkylene group having 3 to 16 carbon atoms. The β-methyl-δ-valerolactone copolymer according to any one of claims 1 to 4, wherein the number average molecular weight is 500 to 200,000. The β-methyl-δ-valerolactone copolymer according to any one of claims 1 to 5, wherein in the general formula (I), the content ratio of the block (E) represented by the following formula is 5 to 95 mass %: . A resin composition comprising the β-methyl-δ-valerolactone copolymer according to any one of claims 1 to 6 and a thermoplastic resin. The resin composition of claim 7 contains 0.1 to 100 parts by mass of the β-methyl-δ-valerolactone copolymer relative to 100 parts by mass of the thermoplastic resin. A resin composition as claimed in claim 7 or 8, wherein the thermoplastic resin comprises polyester. The resin composition of claim 7 or 8, wherein the thermoplastic resin comprises a biodegradable resin. The resin composition of any one of claims 7 to 10, wherein the number average molecular weight of the resin composition is 1,000 to 1,000,000. A shaped body comprising the resin composition of any one of claims 7 to 11. A method for producing a β-methyl-δ-valerolactone copolymer is a method for producing a β-methyl-δ-valerolactone copolymer represented by the following general formula (I) or (II), comprising the following steps: a step (1) of reacting β-methyl-δ-valerolactone, an initiator, and a polymerization catalyst, and subjecting the β-methyl-δ-valerolactone to a ring-opening polymerization to obtain a reaction solution, and a step (2) of adding a terminal modification agent to the reaction solution to subject the terminal modification reaction to obtain the β-methyl-δ-valerolactone copolymer: [In the general formulae (I) and (II), ^R1 represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 14 carbon atoms; R ² represents a linear alkyl group having 1 to 20 carbon atoms, a branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, a group represented by the following formula (X), a group in which one hydrogen atom bonded to a terminal carbon atom of a linear alkyl group having 1 to 20 carbon atoms is substituted by a group represented by the following formula (Y), a group in which one hydrogen atom bonded to at least one terminal carbon atom of a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Y), or a group in which one hydrogen atom bonded to at least one carbon atom of a linear alkyl group having 1 to 20 carbon atoms or a branched alkyl group having 3 to 20 carbon atoms is substituted by a group represented by the following formula (Z); In the following formula (X), the bond represented by *1 is bonded to an oxygen atom; in the following formula (Y), the bond represented by *2 is bonded to the linear alkyl group having 1 to 20 carbon atoms or the branched alkyl group having 3 to 20 carbon atoms; in the following formula (Z), the bond represented by *3 is bonded to the linear alkyl group having 1 to 20 carbon atoms or the branched alkyl group having 3 to 20 carbon atoms; R ³ represents a linear alkylene group having 2 to 20 carbon atoms or a branched alkylene group having 3 to 20 carbon atoms; A represents an oxygen atom, a sulfur atom, or an imino group; n is 2 to 1,000, m is 2 to 1,000, and p is 2 to 1,000; when there are multiple n, m, A, p, R ¹ , R ² , and R ³ , they may be the same or different from each other]. A method for producing a β-methyl-δ-valerolactone copolymer as claimed in claim 13, wherein the polymerization catalyst is an alkaline catalyst. A method for producing a β-methyl-δ-valerolactone copolymer as claimed in claim 13 or 14, wherein the polymerization catalyst is butyl lithium. The method for producing a β-methyl-δ-valerolactone copolymer according to any one of claims 13 to 15, wherein the terminal modification agent is an acid anhydride or an acid halide. A method for producing a β-methyl-δ-valerolactone copolymer according to any one of claims 13 to 16, wherein the terminal modification agent is an acid anhydride. A method for producing a β-methyl-δ-valerolactone copolymer according to any one of claims 13 to 17, wherein in step (2), 1 to 20 molar equivalents of the terminal modifier are added relative to the hydroxyl group of the initiator. The method for producing a β-methyl-δ-valerolactone copolymer according to any one of claims 13 to 18, wherein the number average molecular weight (Mn) of the copolymer is 500 to 200,000. A method for producing a β-methyl-δ-valerolactone copolymer according to any one of claims 13 to 19, wherein the initiator is a polyether having at least one hydroxyl group. A method for producing a β-methyl-δ-valerolactone copolymer as claimed in any one of claims 13 to 20, wherein in the step (2), at least one selected from the β-methyl-δ-valerolactone, the initiator and the polymerization catalyst contained in the reaction solution is not removed, and the terminal modification agent is added to the reaction solution.