Resin composition and resin modifier

Abstract

The present invention provides a resin composition containing: a block copolymer (I) containing a block structural unit (A) mainly composed of a polylactic acid unit (a) and a block structural unit (B) mainly composed of a polyester unit (b); the polyester unit (b) contains a unit derived from an aliphatic diol (b1) having an alkyl group as a branched chain and not having a quaternary carbon, and an aliphatic dicarboxylic acid (b2), the aliphatic diol (b1) having two hydroxyl groups that are primary hydroxyl groups, and the block copolymer (I) has a melting point of less than 180 DEG C.

Description

Technical Field

[0001] The present invention relates to a resin composition and a resin modifier having excellent biodegradability, hydrolysis resistance, heat resistance, and impact resistance. Background Art

[0002] From the viewpoint of environmental protection, development related to bioplastics is actively underway. Polylactic acid, as a bioplastic, is made from renewable resources such as plants like corn produced through photosynthesis and is expected to be utilized in a wide range of fields.

[0003] However, it is known that polylactic acid is more brittle compared to petroleum-based plastics, has poor impact resistance and heat resistance, and is prone to hydrolysis. Therefore, there are cases where the use of polylactic acid as a resin material is restricted. As an attempt to improve the disadvantages of polylactic acid, for example, techniques utilizing stereocomplexation of polylactic acid (for example, refer to Patent Document 1) have been studied. In addition, techniques utilizing urethane polymers having lactic acid units (for example, refer to Patent Document 2), and techniques utilizing a composition of a block copolymer obtained by copolymerizing a specific polyester with polylactic acid and polylactic acid (for example, refer to Patent Documents 3 and 4) have been studied.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2011-153275

[0007] Patent Document 2: International Publication No. 2021 / 210608

[0008] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2014-1261

[0009] Patent Document 4: Japanese Unexamined Patent Application Publication No. 2001-335623 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] For a final product made of a resin material, in order to suppress the progression of aging deterioration, hydrolysis resistance is required. Therefore, bioplastics need to have both biodegradability and hydrolysis resistance depending on the use.

[0012] In addition, for a final product made of a resin material, from the viewpoint of versatility, excellent impact resistance and heat resistance are desired.

[0013] Therefore, the present invention provides a resin composition having excellent biodegradability, hydrolysis resistance, heat resistance, and impact resistance, and a resin modifier capable of improving biodegradability, hydrolysis resistance, heat resistance, and impact resistance.

[0014] Means for Solving the Problem

[0015] In order to solve the above problems, intensive studies have been conducted. As a result, the present inventors have conceived the following present invention and found that the problems can be solved.

[0016] That is, the present invention is as follows.

[0017] [1] A resin composition containing a block copolymer (I) and an aliphatic polyester resin (II),

[0018] The above block copolymer (I) includes a block structural unit (A) mainly composed of polylactic acid units (a) and a block structural unit (B) mainly composed of polyester units (b),

[0019] The above polyester unit (b) contains units derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2),

[0020] The above aliphatic diol (b1) has an alkyl group as a side chain and does not have a quaternary carbon,

[0021] The two hydroxyl groups of the above aliphatic diol (b1) are primary hydroxyl groups,

[0022] The melting point of the above block copolymer (I) is lower than 180 °C.

[0023] [2] The resin composition according to item [1] above, wherein the above aliphatic polyester resin (II) is at least one selected from biomass resins and biodegradable resins.

[0024] [3] The resin composition according to [1] or [2] above, wherein the above aliphatic polyester resin (II) is a polylactic acid resin.

[0025] [4] The resin composition according to any one of [1] to [3] above, wherein the carbon number of the above aliphatic diol (b1) is 4 or more.

[0026] [5] The resin composition according to any one of [1] to [4] above, wherein the carbon number of the above aliphatic diol (b1) is 6 or more.

[0027] [6] The resin composition according to any one of [1] to [5] above, wherein the carbon number of the above aliphatic diol (b1) is 30 or less.

[0028] [7] The resin composition according to any one of [1] to [6] above, wherein the above side chain is a methyl group.

[0029] [8] The resin composition according to any one of [1] to [7] above, wherein the aliphatic diol (b1) is 3-methyl-1,5-pentanediol.

[0030] [9] The resin composition according to any one of [1] to [8] above, wherein the aliphatic dicarboxylic acid (b2) has 4 or more and 12 or less carbon atoms.

[0031]

[10] The resin composition according to any one of [1] to [9] above, wherein the aliphatic dicarboxylic acid (b2) is an acyclic aliphatic dicarboxylic acid.

[0032]

[11] The resin composition according to any one of [1] to

[10] above, wherein the glass transition temperature of the block copolymer (I) is -80°C or higher and -15°C or lower.

[0033]

[12] The resin composition according to any one of [1] to

[11] above, wherein the glass transition temperature of the block copolymer (I) is -80°C or higher and -45°C or lower.

[0034]

[13] The resin composition according to any one of [1] to

[12] above, wherein the melting point of the block copolymer (I) is 110°C or higher.

[0035]

[14] The resin composition according to any one of [1] to

[13] above, wherein the number average molecular weight of the block copolymer (I) is 20,000 to 400,000.

[0036]

[15] The resin composition according to any one of [1] to

[14] above, wherein the number average molecular weight of the block structural unit (B) is 10,000 to 300,000.

[0037]

[16] The resin composition according to any one of [1] to

[15] above, wherein the block structural unit (A) contains a structural unit derived from poly-L-lactic acid or a structural unit derived from poly-D-lactic acid.

[0038]

[17] The resin composition according to any one of [1] to

[16] above, wherein, relative to 100% by mass in total of the block structural unit (A) and the block structural unit (B), the block structural unit (A) is 5% by mass or more and 95% by mass or less.

[0039]

[18] A resin modifier comprising a block copolymer (I), the block copolymer (I) comprising a block structural unit (A) mainly composed of polylactic acid units (a) and a block structural unit (B) mainly composed of polyester units (b).

[0040] The above polyester unit (b) contains units derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2).

[0041] The above aliphatic diol (b1) has an alkyl group as a side chain and does not have a quaternary carbon.

[0042] The two hydroxyl groups of the above aliphatic diol (b1) are primary hydroxyl groups.

[0043] Advantages of the Invention

[0044] According to the present invention, it is possible to provide a resin composition excellent in biodegradability, hydrolysis resistance, heat resistance, and impact resistance, and a resin modifier capable of improving biodegradability, hydrolysis resistance, heat resistance, and impact resistance. Detailed Embodiments

[0045] Hereinafter, an example of an embodiment of the present invention will be described. However, the embodiments shown below are illustrative examples for embodying the technical idea of the present invention, and the present invention is not limited to the following description.

[0046] In the present specification, although preferred modes of the embodiment are given, modes obtained by combining two or more of the respective preferred modes are also preferred modes. Regarding matters represented by numerical ranges, when there are multiple numerical ranges, their lower limits and upper limits can be selectively combined as preferred modes. In addition, when there is a description of a numerical range such as "XX to YY", it means "XX or more and YY or less".

[0047] In the present specification, "~ unit" (where "~" represents a polymer) means "structural unit derived from ~". For example, "polylactic acid unit" means "structural unit derived from polylactic acid", and "polyester unit" means "structural unit derived from polyester".

[0048] In addition, in the present specification, the "main chain" of a polymer means the longest molecular chain in the polymer molecule unless otherwise specified.

[0049] [Resin Composition]

[0050] The resin composition of the present embodiment contains a block copolymer (I) and an aliphatic polyester resin (II). Moreover, the block copolymer (I) includes a block structural unit (A) mainly composed of polylactic acid units (a) and a block structural unit (B) mainly composed of polyester units (b). The polyester unit (b) contains units derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2). The aliphatic diol (b1) has an alkyl group as a side chain and does not have a quaternary carbon. The two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups. The melting point of the block copolymer (I) is lower than 180 °C.

[0051] By making the resin composition contain the block copolymer (I) having a specified constitution, the resin composition becomes a composition excellent in biodegradability, hydrolysis resistance, heat resistance, and impact resistance.

[0052] <Block copolymer (I)>

[0053] The block copolymer (I) includes a block structural unit (A) mainly composed of polylactic acid units (a) and a block structural unit (B) mainly composed of polyester units (b). Moreover, the polyester unit (b) contains units derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2). The aliphatic diol (b1) has an alkyl group as a side chain and does not have a quaternary carbon. The two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups.

[0054] By making the aliphatic diol (b1) have the above constitution, the resin composition becomes a composition having both excellent hydrolysis resistance, heat resistance, and impact resistance.

[0055] In addition, by using the block copolymer (I) that satisfies the above requirements, the resin composition exhibits good biodegradability. Although the reason is not certain, it is presumed that since the block structural unit (B) easily forms an amorphous structure, when the block copolymer (I) undergoes biodegradation, microorganisms can easily enter the polymer structure, achieving good biodegradability, and thus the resin composition also exhibits good biodegradability. In addition, it can be considered that by making the aliphatic diol (b1) have an alkyl group as a side chain, the biodegradability is further improved. On the other hand, it can be considered that when the block structural unit (B) does not form an amorphous structure, it is difficult for microorganisms to enter the polymer structure when the block copolymer (I) undergoes biodegradation, and it is considered difficult to obtain the effects of the present invention. However, the polymer having an amorphous structure is only one factor affecting biodegradability. This is because it can be considered that various factors such as whether microorganisms recognize the amorphous structure as food, whether enzymes and microorganisms can easily approach, the steric hindrance of the main chain, melting point, and crystallinity complexly affect biodegradability. Therefore, good biodegradability cannot be obtained simply because the polymer has an amorphous structure.

[0056] <<Block structural unit (A)>>

[0057] 〈Polylactic acid unit (a)〉

[0058] The block structural unit (A) has a polylactic acid unit (a) as the main component.

[0059] The above-mentioned "main component" means the unit with the highest content ratio among the units constituting the block structural unit (A).

[0060] The content ratio of the polylactic acid unit (a) in the block structural unit (A) is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 85% by mass or more, still more preferably 90% by mass or more, and may also contain 100% by mass. In addition, the upper limit of the polylactic acid unit (a) contained in the block structural unit (A) is not limited, for example, it is 100% by mass or less.

[0061] The polylactic acid constituting the polylactic acid unit (a) can be prepared by the direct condensation method of lactic acid or by the ring-opening polymerization method of lactide. For example, at least one selected from L-lactic acid, D-lactic acid, and DL-lactic acid can be used as the above-mentioned lactic acid. For example, at least one selected from L-lactide, D-lactide, DL-lactide, and meso-lactide can be used as the above-mentioned lactide.

[0062] In addition, as the polylactic acid, poly-L-lactic acid, poly-D-lactic acid, poly-DL-lactic acid, or stereocomplex polylactic acid obtained by mixing poly-L-lactic acid and poly-D-lactic acid can be used.

[0063] On the other hand, from the viewpoints of synthesis cost, complexity, and processability of the block copolymer (I), it is preferred that the polylactic acid is not stereocomplex polylactic acid.

[0064] From the viewpoints of cost and availability of raw materials, the polylactic acid is preferably at least one selected from poly-L-lactic acid, poly-D-lactic acid, and poly-DL-lactic acid, and more preferably at least one selected from poly-L-lactic acid and poly-D-lactic acid.

[0065] From the viewpoints of more excellent biodegradability and hydrolysis resistance, the block structural unit (A) preferably contains 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more of structural units derived from poly-L-lactic acid or structural units derived from poly-D-lactic acid. For example, an example of a preferred embodiment is that the block structural unit (A) is composed of structural units derived from poly-L-lactic acid or structural units derived from poly-D-lactic acid, that is, the structural units derived from poly-L-lactic acid or structural units derived from poly-D-lactic acid are 100% by mass.

[0066] <Units (a') other than the polylactic acid unit (a)>

[0067] The block structural unit (A) may or may not contain units (a') other than the polylactic acid unit (a).

[0068] The monomer serving as the constituent unit (a') is not particularly limited as long as the effects of the present invention are not impaired.

[0069] The content ratio of the unit (a') in the block structural unit (A) is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0070] <Number-average molecular weight of the block structural unit (A)>

[0071] The number-average molecular weight of the block structural unit (A) is preferably from 1,000 to 200,000, more preferably from 2,000 to 100,000, and still more preferably from 3,000 to 50,000. When within the above numerical range, there is a tendency for excellent productivity. Further, from the viewpoints of heat resistance and impact resistance, the number-average molecular weight of the block structural unit (A) is preferably 5,000 or more, more preferably 7,500 or more, and still more preferably 10,000 or more.

[0072] It should be noted that when the block copolymer (I) has a plurality of block structural units (A), the number-average molecular weight of the block structural unit (A) means the sum of all blocks.

[0073] The number-average molecular weight of the block structural unit (A) can be determined from the number-average molecular weight of the block copolymer (I) and the mass content ratio of the block structural unit (A) described later.

[0074] <<Block structural unit (B)>>

[0075] The block structural unit (B) has a polyester unit (b) as the main component.

[0076] The above "main component" means the unit with the highest content ratio among the units constituting the block structural unit (B).

[0077] The content ratio of the polyester unit (b) in the block structural unit (B) is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 85% by mass or more, particularly preferably 90% by mass or more, and may also be 100% by mass. In addition, the upper limit of the polyester unit (b) contained in the block structural unit (B) is not limited, for example, it is 100% by mass or less.

[0078] The polyester unit (b) contains units derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2). Specifically, the polyester unit (b) contains units derived from a polyester obtained by reacting an aliphatic diol (b1) with an aliphatic dicarboxylic acid (b2). The polyester unit (b) may or may not contain units derived from monomers other than the aliphatic diol (b1) and the aliphatic dicarboxylic acid (b2).

[0079] There is no particular limitation on the monomers other than the aliphatic diol (b1) and the aliphatic dicarboxylic acid (b2) within the scope that does not impair the effects of the present invention.

[0080] The total amount of the aliphatic diol (b1) and the aliphatic dicarboxylic acid (b2) in the polyester unit (b) is preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, and may be 100% by mass. In addition, there is no limit to the upper limit of the total amount of the aliphatic diol (b1) and the aliphatic dicarboxylic acid (b2) in the polyester unit (b), for example, it is 100% by mass or less.

[0081] 〈Aliphatic diol (b1)〉

[0082] The aliphatic diol (b1) has an alkyl group as a side chain and does not have a quaternary carbon. Moreover, the two hydroxyl groups possessed by the above aliphatic diol (b1) are primary hydroxyl groups.

[0083] Here, the "side chain" in the aliphatic diol (b1) refers to a partial structure branched from the "main chain" in the aliphatic diol (b1), and no hydroxyl group is bonded to its end.

[0084] Moreover, the "main chain" in the above aliphatic diol (b1) refers to a partial structure of a molecular chain formed by multiple atoms, preferably carbon atoms, connecting the two primary hydroxyl groups in the molecule as the two ends. Therefore, the two primary hydroxyl groups in the aliphatic diol (b1) are located at the two ends of the "main chain" in the aliphatic diol (b1).

[0085] Since the aliphatic diol (b1) has an alkyl side chain, the block structural unit (B) is less likely to crystallize, and in addition, the hydrolysis resistance becomes good. Therefore, the biodegradability of the block copolymer (I) containing the block structural unit (B) becomes good, and in addition, the hydrolysis resistance also becomes good. As a result, the biodegradability of the resin composition containing the block copolymer (I) also becomes good, and in addition, the hydrolysis resistance also becomes good. Furthermore, since the block structural unit (B) is less likely to crystallize, the block structural unit (B) contains an amorphous structure rich in flexibility, and as a result, the impact resistance of the resin composition becomes good.

[0086] In addition, in the aliphatic diol (b1), the number of branched chains is preferably 1 or 2, more preferably 1. In addition, the branched chains are preferably methyl, ethyl, and propyl, more preferably methyl and ethyl, and still more preferably methyl. In addition, when the aliphatic diol (b1) has a plurality of branched chains, each branched chain may be the same or different.

[0087] Since the aliphatic diol (b1) does not have a quaternary carbon, the biodegradability of the block copolymer (I) is improved, and the biodegradability of the resin composition containing the block copolymer (I) is also improved. In addition, it easily reacts with the aliphatic dicarboxylic acid (b2), and the block copolymer (I) can be easily produced.

[0088] Since the two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups, the glass transition temperature of the block copolymer (I) tends to decrease, and the impact resistance of the resin composition (especially the impact resistance at a low temperature of about -40°C to 10°C) is improved. In addition, it easily reacts with the aliphatic dicarboxylic acid (b2), and the block copolymer (I) can be easily produced.

[0089] Since the aliphatic diol (b1) has an alkyl group as a branched chain and does not have a quaternary carbon, and the two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups, the block copolymer (I) and the resin composition containing the block copolymer (I) have excellent biodegradability, hydrolysis resistance, and impact resistance.

[0090] Regarding the carbon number of the aliphatic diol (b1), from the viewpoint of exhibiting excellent hydrolysis resistance and impact resistance (especially the impact resistance at low temperatures), it is preferably 4 or more, more preferably 5 or more, still more preferably 6 or more. From the viewpoint of exhibiting more excellent biodegradability, it is preferably 30 or less, more preferably 18 or less, still more preferably 9 or less. That is, the carbon number of the aliphatic diol (b1) is preferably 4 to 30, more preferably 5 to 18, still more preferably 6 to 9.

[0091] Examples of the aliphatic diol (b1) include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 1,4-pentanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 2-ethyl-1,6-hexanediol, 2-methyl-1,8-octanediol, 2,7-dimethyl-1,8-octanediol, 2-methyl-1,9-nonanediol, etc.

[0092] The aliphatic diol (b1) is preferably at least one selected from 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2,4-diethyl-1,5-pentanediol, and more preferably 3-methyl-1,5-pentanediol.

[0093] The aliphatic diol (b1) may be used alone or in combination of two or more.

[0094] 〈Aliphatic dicarboxylic acid (b2)〉

[0095] Regarding the number of carbon atoms of the aliphatic dicarboxylic acid (b2), there is no limitation as long as the effects of the present invention are not impaired. However, from the viewpoints of exhibiting excellent hydrolysis resistance and impact resistance (especially impact resistance at low temperatures), it is preferably 4 or more, more preferably 5 or more, and further preferably 6 or more. From the viewpoint of exhibiting more excellent biodegradability, it is preferably 12 or less, more preferably 10 or less, and further preferably 8 or less. That is, the number of carbon atoms of the aliphatic dicarboxylic acid (b2) is preferably 4 to 12, more preferably 5 to 10, and further preferably 6 to 8.

[0096] Regarding the aliphatic dicarboxylic acid (b2), from the viewpoints of exhibiting excellent hydrolysis resistance and impact resistance, it is preferably an acyclic aliphatic dicarboxylic acid.

[0097] Examples of the aliphatic dicarboxylic acid (b2) include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid. It is preferably at least one selected from succinic acid, adipic acid, and sebacic acid, more preferably at least one selected from succinic acid and adipic acid, and further preferably adipic acid.

[0098] The aliphatic dicarboxylic acid (b2) may be used alone or in combination of two or more.

[0099] <Preferred combination of aliphatic diol (b1) and aliphatic dicarboxylic acid (b2)>

[0100] From the viewpoint of achieving more excellent biodegradability, hydrolysis resistance and impact resistance, the combination of 3-methyl-1,5-pentanediol and adipic acid, the combination of 3-methyl-1,5-pentanediol and succinic acid, the combination of 2-methyl-1,3-propanediol and adipic acid, the combination of 2-methyl-1,3-propanediol and succinic acid, and the combination of 2,4-diethyl-1,5-pentanediol and adipic acid are examples of preferred embodiments, and the combination of 3-methyl-1,5-pentanediol and adipic acid is an example of a more preferred embodiment.

[0101] <Ratio of aliphatic diol (b1) to aliphatic dicarboxylic acid (b2)>

[0102] The feed molar ratio [aliphatic diol (b1) / aliphatic dicarboxylic acid (b2)] when reacting aliphatic diol (b1) with aliphatic dicarboxylic acid (b2) is preferably 1.4 / 1 to 1 / 1.4, more preferably 1.2 / 1 to 1 / 1.2.

[0103] <Units (b') other than polyester unit (b)>

[0104] The block structural unit (B) may contain units (b') other than the polyester unit (b).

[0105] The monomer as the constituent unit (b') is not particularly limited as long as the effects of the present invention are not impaired.

[0106] The content ratio of the unit (b') in the block structural unit (B) is preferably 50% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, still more preferably 15% by mass or less, and particularly preferably 10% by mass or less.

[0107] <Number-average molecular weight of block structural unit (B)>

[0108] The number-average molecular weight of the block structural unit (B) is preferably 1000 to 300000, more preferably 5000 to 200000, further preferably 7000 to 150000, and can be still more preferably 9000 to 100000. If within the above numerical range, there is a tendency to easily manufacture the block copolymer (I).

[0109] In addition, from the viewpoints of heat resistance and impact resistance, the number-average molecular weight of the block structural unit (B) is preferably 10,000 or more, more preferably 15,000 or more, still more preferably 20,000 or more, and even more preferably 25,000 or more. That is, from the viewpoints of heat resistance and impact resistance, the number-average molecular weight of the block structural unit (B) is preferably 10,000 to 300,000, more preferably 15,000 to 200,000, still more preferably 20,000 to 150,000, and even more preferably 25,000 to 100,000.

[0110] The number-average molecular weight of the block structural unit (B) can be determined from the number-average molecular weight of the block copolymer (I) and the mass content ratio of the block structural unit (B) described later, and specifically, it can be measured by the method described in the examples.

[0111] ≪Structural Unit Ratio of Block Copolymer (I)≫

[0112] Based on 100% by mass of the total of the block structural unit (A) and the block structural unit (B), the block structural unit (A) is preferably 5% by mass or more and 95% by mass or less.

[0113] When the proportion of the above-mentioned block structural unit (A) is 5% by mass or more, the resin composition tends to have more excellent heat resistance. In addition, when the proportion of the above-mentioned block structural unit (A) is 95% by mass or less, the resin composition tends to have more excellent hydrolysis resistance, impact resistance, and biodegradability.

[0114] From the viewpoint of heat resistance, the proportion of the above-mentioned block structural unit (A) is more preferably 10% by mass or more, and still more preferably 15% by mass or more. In addition, from the viewpoints of hydrolysis resistance, impact resistance, biodegradability, etc., the proportion of the above-mentioned block structural unit (A) is more preferably 80% by mass or less, still more preferably 75% by mass or less, even more preferably 70% by mass or less, particularly preferably 60% by mass or less, extremely preferably 50% by mass or less, and most preferably 45% by mass or less.

[0115] The proportion of the block structural unit (A) can be determined by 1 1H-NMR, and specifically, it can be measured by the method described in the examples.

[0116] In addition, the total of the content ratios of the block structural unit (A) and the block structural unit (B) in the block copolymer (I) is preferably 90% by mass or more, more preferably 95% by mass or more, and may also be 100% by mass. In addition, there is no limit to the upper limit of the total of the content ratios of the block structural unit (A) and the block structural unit (B) in the block copolymer (I), for example, it is 100% by mass or less.

[0117] The block copolymer (I) may or may not contain units other than the block structural units (A) and the block structural units (B).

[0118] The units other than the block structural units (A) and the block structural units (B) are not particularly limited as long as the effects of the present invention are not impaired.

[0119] The content ratio of the units other than the block structural units (A) and the block structural units (B) in the block copolymer (I) is preferably 10% by mass or less, more preferably 5% by mass or less.

[0120] <<Bonding form of block copolymer (I)>>

[0121] The bonding form of the block copolymer (I) is preferably a triblock type and a diblock type, more preferably a triblock type. The block copolymer (I) may be a mixture of a triblock type and a diblock type. Specifically, the bonding form is preferably [block structural unit (A)] - [block structural unit (B)] - [block structural unit (A)].

[0122] <<Number-average molecular weight of block copolymer (I)>>

[0123] Regarding the number-average molecular weight of the block copolymer (I), from the viewpoints of hydrolysis resistance, impact resistance, and heat resistance, it is preferably 5000 or more, more preferably 10000 or more, and further preferably 15000 or more. From the viewpoints of ease of manufacture and processability, the number-average molecular weight of the block copolymer (I) is preferably 400000 or less, more preferably 200000 or less, and further preferably 100000 or less. That is, the number-average molecular weight of the block copolymer (I) is preferably 5000 to 400000, more preferably 10000 to 200000, and further preferably 15000 to 100000.

[0124] In addition, from the viewpoints of heat resistance and impact resistance, the number-average molecular weight of the block copolymer (I) is preferably 20000 or more, more preferably 25000 or more, further preferably 30000 or more, and still more preferably 35000 or more. From the viewpoints of heat resistance, impact resistance, ease of manufacture, and processability, the number-average molecular weight of the block copolymer (I) is preferably 20000 to 400000, more preferably 25000 to 200000, and further preferably 30000 to 100000.

[0125] The number-average molecular weight of the block copolymer (I) can be determined by gel permeation chromatography (GPC). Specifically, it can be measured by the method described in the examples.

[0126] <<Melting point of block copolymer (I)>>

[0127] From the viewpoint of processability such as easy melt processing, the melting point of the block copolymer (I) is lower than 180 °C, preferably 175 °C or lower, more preferably 170 °C or lower, and even more preferably 160 °C or lower.

[0128] From the viewpoint of practical heat resistance, the melting point of the block copolymer (I) is preferably 110 °C or higher, more preferably 120 °C or higher, and further preferably 125 °C or higher.

[0129] From the viewpoints of good processability and heat resistance, the melting point of the block copolymer (I) is preferably 110 °C or higher and lower than 180 °C, more preferably 120 °C or higher and 175 °C or lower, further preferably 120 °C or higher and 170 °C or lower, and even more preferably 125 °C or higher and 160 °C or lower.

[0130] The melting point of the block copolymer (I) can be determined using a differential scanning calorimeter, and specifically, it can be measured by the method described in the examples.

[0131] ≪Glass transition temperature of block copolymer (I)≫

[0132] The glass transition temperature of the block copolymer (I) is preferably -80 °C or higher and -15 °C or lower. If it is within the above numerical range, there is a tendency for the resin composition to have excellent flexibility and impact resistance.

[0133] From the viewpoints of low-temperature properties such as impact resistance at low temperatures, the glass transition temperature of the block copolymer (I) is more preferably -20 °C or lower, further preferably -25 °C or lower. In one embodiment of the present invention, it can also be -30 °C or lower, or -35 °C or lower. Additionally, in other embodiments of the present invention, the glass transition temperature of the block copolymer (I) can also be -45 °C or lower.

[0134] The lower limit value of the glass transition temperature of the block copolymer (I) is preferably low. However, in one embodiment of the present invention, for example, it can be -70 °C or higher, or -60 °C or higher, or -50 °C or higher, or -40 °C or higher. Additionally, in other embodiments of the present invention, the glass transition temperature of the block copolymer (I) can be -70 °C or higher, or -60 °C or higher, or -50 °C or higher.

[0135] The glass transition temperature of the block copolymer (I) can be determined by differential scanning calorimetry.

[0136] <Method for producing block copolymer (I)>

[0137] The method for producing the block copolymer (I) can adopt a known production method.

[0138] A known production method of the block copolymer (I) may be, for example, a method of synthesizing a polyester constituting the polyester unit (b) and subjecting the polyester to a polymerization reaction with lactide.

[0139] The above polyester can be synthesized by a known method. For example, an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2) can be reacted using an esterification catalyst (such as tin octoate, tin chloride, tin oxide) to synthesize the polyester.

[0140] When subjecting the polyester to a polymerization reaction with lactide, it is preferable to use a ring-opening polymerization catalyst (such as tin octoate, tin chloride, tin oxide). Examples of the polymerization reaction include solution polymerization, melt polymerization, interfacial polycondensation, etc., and known polymerization reaction conditions can be set for all of them.

[0141] In addition, as another known production method of the block copolymer (I), for example, it may also be a method of separately synthesizing polylactic acid constituting the polylactic acid unit (a) and a polyester constituting the polyester unit (b) and reacting the polylactic acid with the polyester.

[0142] Polylactic acid can be synthesized by a known method. For example, polylactic acid can be synthesized by reacting lactic acid using a direct condensation method, or polylactic acid can be synthesized by reacting lactide using a ring-opening polymerization method.

[0143] When subjecting polylactic acid to a polymerization reaction with a polyester, it is preferable to use an esterification catalyst (such as tin octoate, tin chloride, tin oxide). Examples of the polymerization reaction include solution polymerization, melt polymerization, interfacial polycondensation, etc., and known polymerization reaction conditions can be set for all of them.

[0144] <Aliphatic polyester resin (II)>

[0145] In the present embodiment, regarding the aliphatic polyester resin (II), from the viewpoint of biodegradability, it is preferably at least one selected from biomass resins and biodegradable resins.

[0146] As the aliphatic polyester resin (II), for example, polylactic acid (PLA), polycaprolactone (PCL), poly(ε-caprolactone / butylene succinate) (PCLBS), polybutylene succinate (PBS), poly(butylene succinate / adipate) (PBSA), poly(butylene succinate / carbonate) (PEC), poly(ethylene terephthalate / succinate) (PETS), poly(butylene adipate / terephthalate) (PBAT), poly(tetramethylene adipate / terephthalate) (PTMT), poly(ethylene succinate) (PES), polyglycolic acid (PGA), poly(ethylene furandicarboxylate) (PEF), polyhydroxyalkanoate (PHA) [such as polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), etc.] and copolymers containing them can be cited.

[0147] The aliphatic polyester resin (II) can be used alone in one kind or two or more kinds can be used in combination.

[0148] Regarding the aliphatic polyester resin (II), from the viewpoints of exhibiting more excellent hydrolysis resistance, heat resistance, impact resistance, and biodegradability, PLA, PBS, PBSA, and PBAT are preferred, and PLA and its copolymers, that is, polylactic acid-based resins, are more preferred.

[0149] When using a polylactic acid-based resin as the aliphatic polyester resin (II), as the polylactic acid-based resin, for example, at least one selected from homopolymers of L-lactic acid, homopolymers of D-lactic acid, copolymers of L-lactic acid and D-lactic acid, homopolymers of DL-lactic acid, copolymers of DL-lactic acid and L-lactic acid, copolymers of DL-lactic acid and D-lactic acid, and polymers of lactide which is a cyclic dimer of lactic acid can be cited.

[0150] In addition, the polylactic acid-based resin can also be a copolymer of lactic acid and other aliphatic hydroxycarboxylic acids, aliphatic dicarboxylic acids, aliphatic diols, aromatic dicarboxylic acids, etc. other than lactic acid. The above copolymer preferably contains 70 mol% or more of structural units derived from lactic acid, more preferably 80 mol% or more, and still more preferably 90 mol% or more.

[0151] Among them, as the polylactic acid-based resin, a homopolymer of L-lactic acid, a homopolymer of D-lactic acid, or a copolymer of L-lactic acid and D-lactic acid is preferred, and a homopolymer of L-lactic acid is more preferred.

[0152] The polylactic acid-based resin can be used alone in one kind or two or more kinds can be used in combination.

[0153] Commercially available products can also be used as the polylactic acid-based resin. As commercially available products, for example, "trade name INGEO series" manufactured by NatureWorks, "trade name Luminy series" manufactured by TOTAL CORBION, "Revode" series manufactured by Zhejiang HisunBiomaterials Co., Ltd., and "trade name SUPLA" manufactured by SUPLA Material Technology Co., Ltd. can be cited.

[0154] Regarding the weight-average molecular weight of the polylactic acid-based resin, from the viewpoints of impact resistance and heat resistance, it is preferably 50,000 or more, more preferably 100,000 or more, and further preferably 150,000 or more. From the viewpoints of moldability and compatibility with the block copolymer (I), it is preferably 600,000 or less, more preferably 550,000 or less, and further preferably 500,000 or less. That is, the weight-average molecular weight of the polylactic acid-based resin is preferably 50,000 to 600,000, more preferably 100,000 to 550,000, and further preferably 150,000 to 500,000.

[0155] The weight-average molecular weight of the polylactic acid-based resin can be determined by gel permeation chromatography (GPC) and calculated in terms of standard polystyrene conversion. In addition, when using commercially available products, the catalog values can be adopted.

[0156] <Content ratio>

[0157] In the resin composition of the present embodiment, based on 100% by mass in total of the block copolymer (I) and the aliphatic polyester-based resin (II), it preferably contains 0.5 to 50% by mass, more preferably contains 1 to 40% by mass, further preferably contains 1.5 to 30% by mass, and still more preferably contains 2 to 20% by mass of the block copolymer (I). If it is the above content ratio, a resin composition with more excellent hydrolysis resistance, heat resistance, and impact resistance can be prepared.

[0158] In the resin composition of the present embodiment, based on 100% by mass in total of the block copolymer (I) and the aliphatic polyester-based resin (II), it preferably contains 50 to 99.5% by mass, more preferably contains 60 to 99% by mass, further preferably contains 70 to 98.5% by mass, and still more preferably contains 80 to 98% by mass of the aliphatic polyester-based resin (II). If it is the above content ratio, a resin composition with more excellent hydrolysis resistance, heat resistance, and impact resistance can be prepared.

[0159] In the resin composition of the present embodiment, based on 100% by mass in total of the block copolymer (I) and the aliphatic polyester resin (II), it preferably contains 0.1 to 40% by mass, more preferably contains 0.3 to 30% by mass, still more preferably contains 0.5 to 25% by mass, and even more preferably contains 1 to 15% by mass of the block structural unit (A). If it is the above-mentioned content ratio, a resin composition with more excellent hydrolysis resistance, heat resistance and impact resistance can be prepared.

[0160] In the resin composition of the present embodiment, based on 100% by mass in total of the block copolymer (I) and the aliphatic polyester resin (II), it preferably contains 0.2 to 40% by mass, more preferably contains 0.5 to 30% by mass, still more preferably contains 1 to 20% by mass, and even more preferably contains 1.5 to 15% by mass of the block structural unit (B). If it is the above-mentioned content ratio, a resin composition with more excellent hydrolysis resistance, heat resistance and impact resistance can be prepared.

[0161] The total content ratio of the block copolymer (I) and the aliphatic polyester resin (II) in the resin composition of the present embodiment is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more. The total content ratio of the block copolymer (I) and the aliphatic polyester resin (II) in the resin composition of the present embodiment may also be 100% by mass or less. If it is the above-mentioned content ratio, the effects of the present invention can be more significantly exerted.

[0162] <Other components>

[0163] In the resin composition of the present embodiment, in addition to the block copolymer (I) and the aliphatic polyester resin (II), a plasticizer, a resin other than the above-mentioned aliphatic polyester resin (II), and other additives may also be contained.

[0164] <Plasticizer>

[0165] For the purpose of adjusting the resin composition to a viscosity suitable for molding, obtaining a molded product with a desired hardness, etc., a plasticizer may be contained. There is no particular limitation on the plasticizer, however, a plasticizer having biodegradability in any of the environments of industrial compost, domestic compost, soil and sea is preferred. For example, suitable examples include vegetable esters such as rapeseed oil and castor oil, synthetic esters such as glyceryl triacetate, diethyl phthalate, and triethyl citrate, polyhydric alcohols such as ethylene glycol and trimethylolpropane and their derivatives, and sugars such as sorbitol. They may be used alone or in combination of two or more.

[0166] <Resin other than the aliphatic polyester resin (II)>

[0167] The resin other than the aliphatic polyester resin (II) is not particularly limited, but a resin having biodegradability in any environment of industrial compost, household compost, soil, and ocean is preferred. For example, suitable examples include polyvinyl alcohol, cellulose resins such as cellulose acetate, starch and its esters, 4-nylon, etc. They can be used alone or in combination of two or more.

[0168] <Additives>

[0169] In the resin composition of the present embodiment, additives may be further contained in addition to the block copolymer (I) and the aliphatic polyester resin (II).

[0170] Examples of the additives include inorganic fillers, softeners, heat aging inhibitors, antioxidants, hydrolysis inhibitors, light stabilizers, antistatic agents, mold release agents, flame retardants, foaming agents, pigments, dyes, brighteners, ultraviolet absorbers, lubricants, etc. They can be used alone or in combination of two or more.

[0171] When using the above additives, the content of the additives in the resin composition can be appropriately determined according to the desired physical properties of the resin composition.

[0172] [Manufacturing method of resin composition]

[0173] The manufacturing method of the resin composition of the present embodiment is not particularly limited, as long as the block copolymer (I), the aliphatic polyester resin (II), and the additives used as needed are uniformly mixed.

[0174] Examples of the mixing method include a method of melt-kneading using a single-screw extruder, a multi-screw extruder, a Banbury mixer, a heating roll, a Brabender plastograph, various kneaders, etc., or a method of melt-kneading by supplying each component from different feeding ports.

[0175] In addition, pre-mixing can also be performed before melt-kneading. Examples of the pre-mixing method include a method using mixers such as a Henschel mixer, a high-speed mixer, a V-type mixer, a screw-type mixer, a drum mixer, a conical mixer, etc. Regarding the temperature during melt-kneading, considering the melting point and decomposition temperature of the block copolymer (I) and the aliphatic polyester resin (II), it can be preferably arbitrarily selected in the range of 140 to 220 °C.

[0176] [Resin modifier]

[0177] By using a resin composition obtained by mixing the block copolymer (I) and the aliphatic polyester resin (II) together, the hydrolysis resistance, heat resistance, and impact resistance can be improved.

[0178] Therefore, the present invention provides a resin modifier containing a block copolymer (I).

[0179] In addition, as a suitable embodiment, the use of the block copolymer (I) as a resin modifier for an aliphatic polyester resin (II) can be cited.

[0180] Examples

[0181] Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited to them.

[0182] The compounds used in the examples and comparative examples are as follows.

[0183] 3-Methyl-1,5-pentanediol (manufactured by Kuraray Co., Ltd.)

[0184] Adipic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0185] Tin (II) octoate (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0186] Toluene (manufactured by Kishida Chemical Co., Ltd.)

[0187] L-Lactide (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0188] D-Lactide (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0189] Methanol (manufactured by Fujifilm Wako Pure Chemical Corporation)

[0190] Succinic acid (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0191] 2-Methyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0192] 2,4-Diethyl-1,5-pentanediol (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0193] Propylene glycol (manufactured by Fujifilm Wako Pure Chemical Corporation)

[0194] For the block copolymer, polymer, and physical properties of the resin composition in the examples and comparative examples, the following methods were used for measurement or evaluation.

[0195] (1) Number average molecular weight (Mn)

[0196] Using gel permeation chromatography (GPC), the number-average molecular weight (Mn) of the block copolymer and the polymer was determined in terms of standard polystyrene. In addition, the Mn of the block structural unit (B) was determined from the Mn of the block copolymer and the mass fraction of the block structural unit (B), and the Mn of the block structural unit (B') was determined from the Mn of the block copolymer and the mass fraction of the block structural unit (B').

[0197] 〈Measurement conditions of GPC〉

[0198] Apparatus: GPC apparatus “HLC-8220” manufactured by Tosoh Corporation

[0199] Separation column: “TSKgel SuperMultipore HZ-M (column diameter = 4.6 mm, column length = 15 cm)” manufactured by Tosoh Corporation (two columns were used in series)

[0200] Eluent: Tetrahydrofuran (THF)

[0201] Eluent flow rate: 0.35 mL / min

[0202] Column temperature: 40 °C

[0203] Detection method: Differential refractive index (RI)

[0204] Injection volume: 10 μL

[0205] Concentration: 1 mg / 1 mL (block copolymer / THF)

[0206] (2) Hard ratio (mass %) (mass fraction of the block structural unit (A) mainly composed of the polylactic acid unit (a))

[0207] Using 1 1H-NMR, the hard ratio of the block copolymer and the polymer was calculated. Based on the area ratio of the signal around 5.2 ppm from the polylactic acid unit and the signal around 0.9 ppm from the structural unit (B) mainly composed of the polyester unit (b) in the obtained spectrum, the molar ratio of the block structural unit (A) to the block structural unit (B) was calculated, or based on the area ratio of the signal around 5.2 ppm from the polylactic acid unit and the signal around 0.9 ppm from the structural unit (B') mainly composed of the polyester unit (b') in the obtained spectrum, the molar ratio of the block structural unit (A) to the block structural unit (B') was calculated. By multiplying this molar ratio by the molecular weight of the block structural unit to obtain a mass ratio, and adjusting so that the sum of this mass ratio is 100, the mass ratio of the block structural unit (A) was set as the hard ratio.

[0208] 〈 1 Measurement conditions of 1H-NMR〉

[0209] Apparatus: Nuclear magnetic resonance apparatus "JNM-ECX400" manufactured by JEOL Ltd.

[0210] Solvent: Deuterated chloroform

[0211] Measurement temperature: 50 °C

[0212] Number of accumulations: 1024 times

[0213] Rate of temperature increase: 10 °C / min

[0214] (3) Melting point (°C)

[0215] The melting points of the block copolymer and the polymer were measured using a differential scanning calorimeter according to the method described in JIS K7121:2012. In the case where multiple peaks were observed, the melting point of one of the peaks on the highest temperature side was set as the melting point of the block copolymer.

[0216] Apparatus: Differential scanning calorimetry apparatus "DSC822" manufactured by Mettler Toledo GmbH

[0217] Measurement conditions: Rate of temperature increase 10 °C / min

[0218] (4) Glass transition temperature (°C)

[0219] The glass transition temperatures of the block copolymer and the resin composition were measured using a differential scanning calorimeter according to the method described in JIS K7121:2012.

[0220] Apparatus: Differential scanning calorimetry apparatus "DSC822" manufactured by Mettler Toledo GmbH

[0221] Measurement conditions: Rate of temperature increase 10 °C / min

[0222] (5) Biodegradability of the resin composition (compost)

[0223] The biodegradability of the resin composition in compost was measured according to the method based on ISO 14855-2:2018. If the decomposition rate after 15 days is 10% by mass or more, it is evaluated as A, and if it is less than 10% by mass, it is evaluated as B.

[0224] (6) Impact strength (kJ / m 2 )

[0225] <Production of test piece for impact strength measurement>

[0226] For the resin composition, using a vacuum hot pressing device ("IMC-183B" manufactured by Imoto Seisakusho Co., Ltd.), it was depressurized to -0.1 MpaG with an oil rotary pump, preheated at 200 °C for 5 minutes, and then pressed at 50 kN for 3 minutes. Subsequently, using a cooling pressing device equipped with water flow cooling at 70 kgf / cm 2 Pressed for 3 minutes to produce a pressed plate with a thickness of 3.0 mm. A strip-shaped piece of 80 × 10 mm was cut out from the obtained pressed plate and subjected to crystallization treatment in a constant temperature bath at 110 °C for 3 hours. A V-notch was processed at the center of the long side (remaining width 8 mm, tip radius 0.25 mm) to produce a notched strip-shaped test piece.

[0227] <Impact strength measurement>

[0228] The above-mentioned notched strip-shaped test piece made of the resin composition was stored for more than 24 hours under the conditions of 23 °C and a humidity of 49%. Using a Charpy impact tester ("DG-CB" manufactured by Toyo Seiki Seisakusho Co., Ltd.), the impact strength was measured under the conditions of 23 °C and a humidity of 49% with a pendulum load of 2 J. The measured value was the average of 5 times.

[0229] (7)Haze (%)

[0230] For the resin composition, using a vacuum hot pressing device ("IMC-183B" manufactured by Imoto Seisakusho Co., Ltd.), it was depressurized to -0.1 MpaG with an oil rotary pump, preheated at 200 °C for 5 minutes, and then pressed at 40 kN for 1 minute. Subsequently, using a cooling pressing device equipped with water flow cooling at 20 kgf / cm 2 Pressed for 1 minute to produce a pressed plate with a thickness of 0.125 mm. A 50 × 50 mm square piece was cut out from the obtained pressed plate. Using a "Spectral Haze Meter SH7000" manufactured by Nippon Denshoku Industries Co., Ltd. and a light source D65, the haze of the above test piece was measured according to the method based on JIS-K7136.

[0231] (8)Heat deflection temperature (°C)

[0232] <Production of test piece for heat deflection temperature>

[0233] For the resin composition, using a vacuum hot pressing device ("IMC-183B" manufactured by Imoto Seisakusho Co., Ltd.), it was depressurized to -0.1 MpaG with an oil rotary pump, preheated at 200 °C for 5 minutes, and then pressed at 50 kN for 3 minutes. Subsequently, using a cooling pressing device equipped with water flow cooling at 70 kgf / cm 2Press for 3 minutes to produce a pressed board with a thickness of 3.0 mm. Cut out a strip with a size of 80×10 mm from the obtained pressed board, and perform crystallization treatment in a constant temperature bath at 110°C for 3 hours to produce a strip test piece.

[0234] <Load Deflection Temperature Measurement>

[0235] Store the above-mentioned strip test piece made of the resin composition at 23°C and a humidity of 49% for more than 24 hours. Use a load deflection temperature tester ("S-3M" manufactured by Toyo Seiki Seisaku-sho, Ltd.) to measure the load deflection temperature when measured in a flat position with a load of 0.45 MPa. The measured value is the average of three times.

[0236] (9)Hydrolysis Resistance

[0237] <Manufacture of Test Piece for Hydrolysis Resistance>

[0238] Manufacture a test piece for hydrolysis resistance (strip test piece) using the same method as described in the above-mentioned <Manufacture of Test Piece for Load Deflection Temperature>.

[0239] <Hydrolysis Resistance Test>

[0240] Use the above-mentioned strip test piece made of the resin composition to measure the load deflection temperature (1) using the same method as described in the above-mentioned <Load Deflection Temperature Measurement>.

[0241] Then, immerse the test piece made in the same way as the strip test piece for measuring the load deflection temperature (1) in 100 mL of ion-exchanged water with a pH of 7, take it out after placing it at 50°C for 1 week, store it at 23°C and a humidity of 49% for more than 24 hours, and then use this strip test piece to measure the load deflection temperature (2) using the same method as described in the above-mentioned <Load Deflection Temperature Measurement>.

[0242] Evaluate the case where the difference between the load deflection temperature (1) and the load deflection temperature (2) is less than 5°C as A, and the case where it is 5°C or more as B.

[0243] [Manufacturing Example 1]

[0244] In a flask equipped with an apparatus capable of distilling off the generated liquid and a vacuum pump, 3-methyl-1,5-pentanediol and adipic acid are added such that the molar ratio of 3-methyl-1,5-pentanediol / adipic acid = 1.1 / 1. Further, stannous octoate is added to be 0.1% by mass relative to the total weight of 3-methyl-1,5-pentanediol and adipic acid. Under a nitrogen atmosphere and at normal pressure, it is heated at 160 °C for 3 h and then at 220 °C for 3 h while distilling off water and carrying out the reaction. Then, it is depressurized to 2000 Pa and reacted for 3 h, and then depressurized to 80 Pa, and the reaction is carried out while appropriately confirming until the number-average molecular weight reaches 9500, thereby synthesizing a polymer containing a structural unit (B') mainly composed of polyester units. After the reaction is completed, it is returned to normal pressure, cooled to 80 °C, and then toluene is added to dilute the solid content concentration to 40% by mass. Then, the above toluene solution is poured into methanol in an amount twice the total amount of the solution. The supernatant is discarded, and methanol in the same amount as the amount of the poured toluene solution is added again for washing. The supernatant is discarded, and the recovered insoluble component is dried in a vacuum dryer at 40 °C to remove the organic volatile components, thereby obtaining a polymer containing a structural unit (B') mainly composed of polyester units.

[0245] Toluene is added again to the purified polymer containing the structural unit (B'), and after diluting to a solid content concentration of 33% by mass, the temperature is raised to 140 °C, whereby 10% by weight of the added toluene is distilled off to carry out dehydration in the system.

[0246] Subsequently, it is cooled to 80 °C, and the polymer containing the structural unit (B') and L-lactide are added such that the mass ratio of the polymer containing the structural unit (B') / L-lactide = 50 / 50. Further, the toluene in the weight portion distilled off above is added to adjust the solid content concentration to 50% by mass. Subsequently, when the temperature is raised to 100 °C, stannous octoate is added to be 0.1% by mass relative to the polymer containing the structural unit (B'), and it is reacted for 4 h, thereby obtaining a toluene solution of a block copolymer containing a block structural unit (A) mainly composed of polylactic acid units (a) and a block structural unit (B) mainly composed of polyester units (b).

[0247] Toluene is added to this solution, and after diluting the solid content concentration to 40% by mass, the above toluene solution is poured into methanol in an amount twice the total amount of the solution to precipitate the solid. The supernatant methanol is discarded, and methanol in the same amount as the amount of the poured toluene solution is added again for washing. The methanol is discarded, and the recovered solid is dried in a vacuum dryer at 40 °C to remove the organic volatile components, thereby obtaining a block copolymer (I-1) containing a block structural unit (A) mainly composed of polylactic acid units (a) and a block structural unit (B) mainly composed of polyester units (b).

[0248] The above-described measurement was performed on the obtained block copolymer (I-1). The results are shown in Table 1-1.

[0249] [Production Example 2]

[0250] By adjusting the reaction time during the synthesis of the polymer containing the structural unit (B') mainly composed of the polyester unit (b) to adjust the number-average molecular weight, changing the mass ratio of the L-lactide used, and appropriately changing the dilution concentration during the synthesis to a concentration that is easy to handle, a block copolymer (I-2) containing a block structural unit (A) mainly composed of the polylactic acid unit (a) and a block structural unit (B) mainly composed of the polyester unit (b) was synthesized in the same manner as in Production Example 1, except for the above.

[0251] The above-described measurement was performed on the obtained block copolymer (I-2). The results are shown in Table 1-1.

[0252] [Production Example 3]

[0253] Using succinic acid in place of adipic acid, by adjusting the reaction time during the synthesis of the polymer containing the structural unit (B') mainly composed of the polyester unit to adjust the number-average molecular weight, changing the mass ratio of the L-lactide used, and appropriately changing the dilution concentration during the synthesis to a concentration that is easy to handle, a block copolymer (I-3) containing a block structural unit (A) mainly composed of the polylactic acid unit (a) and a block structural unit (B) mainly composed of the polyester unit (b) was synthesized in the same manner as in Production Example 1, except for the above.

[0254] The above-described measurement was performed on the obtained block copolymer (I-3). The results are shown in Table 1-1.

[0255] [Production Example 4]

[0256] Using 2-methyl-1,3-propanediol in place of 3-methyl-1,5-pentanediol, by adjusting the reaction time during the synthesis of the polymer containing the structural unit (B') mainly composed of the polyester unit to adjust the number-average molecular weight, changing the mass ratio of the L-lactide used, and appropriately changing the dilution concentration during the synthesis to a concentration that is easy to handle, a block copolymer (I-4) containing a block structural unit (A) mainly composed of the polylactic acid unit (a) and a block structural unit (B) mainly composed of the polyester unit (b) was synthesized in the same manner as in Production Example 1, except for the above.

[0257] The above-described measurement was performed on the obtained block copolymer (I-4). The results are shown in Table 1-1.

[0258] [Production Example 5]

[0259] Use 2-methyl-1,3-propanediol in place of 3-methyl-1,5-pentanediol, use succinic acid in place of adipic acid, adjust the number-average molecular weight by adjusting the reaction time during the synthesis of a polymer containing a structural unit (B') having a polyester unit as the main unit, change the mass ratio of L-lactide used, and appropriately change the dilution concentration during synthesis to a concentration that is easy to handle. Other than that, synthesize a block copolymer (I-5) containing a block structural unit (A) having a polylactic acid unit (a) as the main unit and a block structural unit (B) having a polyester unit (b) as the main unit in the same manner as in Production Example 1.

[0260] Perform the above measurements on the obtained block copolymer (I-5). The results are shown in Table 1-1.

[0261] [Production Example 6]

[0262] Use 2,4-diethyl-1,5-pentanediol in place of 3-methyl-1,5-pentanediol, adjust the number-average molecular weight by adjusting the reaction time during the synthesis of a polymer containing a structural unit (B') having a polyester unit as the main unit, change the mass ratio of L-lactide used, and appropriately change the dilution concentration during synthesis to a concentration that is easy to handle. Other than that, synthesize a block copolymer (I-6) containing a block structural unit (A) having a polylactic acid unit (a) as the main unit and a block structural unit (B) having a polyester unit (b) as the main unit in the same manner as in Production Example 1.

[0263] Perform the above measurements on the obtained block copolymer (I-6). The results are shown in Table 1-1.

[0264] [Production Examples 7 to 14]

[0265] Adjust the number-average molecular weight by adjusting the reaction time during the synthesis of a polymer containing a structural unit (B') having a polyester unit (b) as the main unit, change the mass ratio of L-lactide used, and appropriately change the dilution concentration during synthesis to a concentration that is easy to handle. Other than that, synthesize block copolymers (I-7) to (I-14) containing a block structural unit (A) having a polylactic acid unit (a) as the main unit and a block structural unit (B) having a polyester unit (b) as the main unit in the same manner as in Production Example 1.

[0266] Perform the above measurements on the obtained block copolymers (I-7) to (I-14). The results are shown in Tables 1-2 to 1-4.

[0267] [Production Example 15]

[0268] The number-average molecular weight was adjusted by adjusting the reaction time during the synthesis of the polymer containing the structural unit (B') having a polyester unit (b) as the main unit. A mixture of L-lactide and D-lactide (L-lactide:D-lactide = 95:5 (mass ratio)) was used instead of L-lactide, and the dilution concentration during the synthesis was appropriately changed to a concentration that is easy to handle. Except for this, a block copolymer (I-15) containing a block structural unit (A) having a polylactic acid unit (a) as the main unit and a block structural unit (B) having a polyester unit (b) as the main unit was synthesized in the same manner as in Production Example 1.

[0269] The above-described measurement was performed on the obtained block copolymer (I-15). The results are shown in Table 1-4.

[0270] [Production Example 16]

[0271] The number-average molecular weight was adjusted by adjusting the reaction time during the synthesis of the polymer containing the structural unit (B') having a polyester unit (b) as the main unit. The mass ratio of L-lactide to D-lactide used was set to 80:20, and the dilution concentration during the synthesis was appropriately changed to a concentration that is easy to handle. Except for this, a block copolymer (I-16) containing a block structural unit (A) having a polylactic acid unit (a) as the main unit and a block structural unit (B) having a polyester unit (b) as the main unit was synthesized in the same manner as in Production Example 15.

[0272] The above-described measurement was performed on the obtained block copolymer (I-16). The results are shown in Table 1-4.

[0273] [Comparative Production Example 1]

[0274] In a flask equipped with an apparatus capable of distilling off the generated liquid and a vacuum pump, propylene glycol and succinic acid are added such that the molar ratio of propylene glycol / succinic acid = 1.1 / 1. Further, stannous octoate is added to be 0.1% by mass based on the total weight of propylene glycol and succinic acid. Under a nitrogen atmosphere, it is heated at 160 °C for 3 h at normal pressure and then at 220 °C for 3 h while distilling off water and carrying out the reaction. Then, the pressure is reduced to 2000 Pa and reacted for 3 h, and then the pressure is reduced to 80 Pa, and the reaction is carried out while appropriately confirming until the number-average molecular weight reaches 26600, thereby synthesizing a polymer containing a structural unit (C) mainly composed of polyester units. After the reaction is completed, the pressure is restored to normal pressure, the temperature is cooled to 80 °C, toluene is added to dilute the solid content concentration to 40% by mass, and then the above toluene solution is poured into methanol in an amount twice the total amount of the solution. The supernatant is discarded, and methanol in the same amount as the amount of the poured toluene solution is added again for washing. The supernatant is discarded, and the recovered insoluble components are dried in a vacuum dryer at 40 °C to remove organic volatile components, thereby obtaining a polyester-based polymer (C-1) containing a structural unit (C) mainly composed of polyester units.

[0275] [Comparative Production Example 2]

[0276] Propylene glycol is used instead of 3-methyl-1,5-pentanediol, and succinic acid is used instead of adipic acid. By adjusting the reaction time during the synthesis of a polymer containing a structural unit (C') mainly composed of polyester units, the number-average molecular weight is adjusted, the mass ratio of the used L-lactide is changed, and the dilution concentration during synthesis is appropriately changed to a concentration easy to operate. Except for this, a block copolymer (I'-1) is synthesized in the same manner as in Production Example 1.

[0277] The above measurements are carried out on the obtained block copolymer (I'-1). The results are shown in Table 2.

[0278] [Examples 1 to 21 and Comparative Examples 2 and 3]

[0279] The block copolymers and polymers obtained in the production examples and the polylactic acid-based polymer "INGEO 2500HP" (manufactured by NatureWorks LLC) as the aliphatic polyester-based resin (II) are put into a kneader Laboplastmill (manufactured by Toyo Seiki Seisaku-sho, Ltd., product name "3S150", roll mill model "R60") according to the formulations shown in Tables 1 and 2, and melt-kneaded at a barrel temperature of 210 °C and a screw rotation speed of 50 rpm for 5 minutes to obtain a resin composition. The above measurements and evaluations are carried out on the obtained resin composition. The results are shown in Tables 1-1 to 1-4 and 2.

[0280] [Comparative Example 1]

[0281] A resin composition was obtained in the same manner as in Example 1, except that the block copolymer (I) was not used and the aliphatic polyester resin (II) was changed to the formulation shown in Table 2.

[0282] The obtained resin composition was subjected to the above-described measurement and evaluation. The results are shown in Table 2.

[0283]

[0284]

[0285]

[0286]

[0287]

[0288] The compounds represented by the abbreviated symbols in Tables 1 and 2 are as follows.

[0289] PLLA: Poly-L-lactic acid

[0290] PDLLA: Poly-DL-lactic acid

[0291] MPD: 3-Methyl-1,5-pentanediol

[0292] DEPD: 2,4-Diethyl-1,5-pentanediol

[0293] MPDiol: 2-Methyl-1,3-propanediol

[0294] AA: Adipic acid

[0295] SA: Succinic acid

[0296] PG: Propylene glycol

[0297] As shown in the examples of Table 1, regarding the resin composition of the present embodiment containing the block copolymer (I) and the aliphatic polyester resin (II), and the block copolymer (I) includes a block structural unit (A) mainly composed of polylactic acid units (a) and a block structural unit (B) mainly composed of polyester units (b) having a specific structure, excellent hydrolysis resistance can be confirmed by hydrolysis resistance evaluation. In addition, regarding the resin composition of the present embodiment, excellent impact resistance can also be confirmed by impact strength measurement, and excellent heat resistance can be confirmed by heat deflection temperature measurement. Furthermore, it is confirmed that the biodegradability and transparency of the resin composition of the present embodiment are also excellent. In addition, based on the above results, it can be said that the block copolymer (I) containing the block structural unit (A) mainly composed of polylactic acid units (a) and the block structural unit (B) mainly composed of polyester units (b) having a specific structure is suitable for use as a resin modifier.

[0298] On the other hand, the resin composition obtained in Comparative Example 1 is a resin composition with poor impact resistance because it does not contain the block copolymer (I).

[0299] In addition, the resin composition obtained in Comparative Example 2 is a resin composition with poor hydrolysis resistance, impact resistance, and transparency. It is considered that the main reason for this result is that instead of using a block copolymer, a polyester polymer obtained by reacting propylene glycol and succinic acid is used.

[0300] In addition, the resin composition obtained in Comparative Example 3 is also a resin composition with poor hydrolysis resistance and impact resistance, similar to Comparative Example 2. It is considered that the main reason for this result is that the block copolymer contains propylene glycol in which the two hydroxyl groups of the diol are not primary hydroxyl groups as a structural unit.

[0301] As shown in the results of the above examples, the biodegradability, hydrolysis resistance, impact resistance, and heat resistance of the resin composition of the present embodiment are excellent. In addition, the block copolymer (I) is suitable for use as a resin modifier. Therefore, the industrial usefulness of the resin composition and resin modifier of the present embodiment is extremely high.

Claims

1. A resin composition containing a block copolymer I and an aliphatic polyester resin II, wherein the block copolymer I includes a block structural unit A mainly composed of polylactic acid units a and a block structural unit B mainly composed of polyester units b, the polyester unit b contains units derived from an aliphatic diol b1 and an aliphatic dicarboxylic acid b2, the aliphatic diol b1 has an alkyl group as a side chain and does not have a quaternary carbon, the two hydroxyl groups of the aliphatic diol b1 are primary hydroxyl groups, the melting point of the block copolymer I is lower than 180 °C.

2. The resin composition according to claim 1, wherein the aliphatic polyester resin II is at least one selected from biomass resins and biodegradable resins.

3. The resin composition according to claim 1 or 2, wherein the aliphatic polyester resin II is a polylactic acid-based resin.

4. The resin composition according to claim 1, wherein the aliphatic diol b1 has 4 or more carbon atoms.

5. The resin composition according to claim 1, wherein the aliphatic diol b1 has 6 or more carbon atoms.

6. The resin composition according to any one of claims 1, 4, and 5, wherein the aliphatic diol b1 has 30 or less carbon atoms.

7. The resin composition according to claim 1, wherein the side chain is a methyl group.

8. The resin composition according to claim 1, wherein the aliphatic diol b1 is 3-methyl-1,5-pentanediol.

9. The resin composition according to claim 1, wherein the aliphatic dicarboxylic acid b2 has 4 or more and 12 or less carbon atoms.

10. The resin composition according to claim 1, wherein the aliphatic dicarboxylic acid b2 is an acyclic aliphatic dicarboxylic acid.

11. The resin composition according to claim 1, wherein the glass transition temperature of the block copolymer I is -80 °C or higher and -15 °C or lower.

12. The resin composition according to claim 1, wherein the glass transition temperature of the block copolymer I is -80 °C or higher and -45 °C or lower.

13. The resin composition according to claim 1, wherein the melting point of the block copolymer I is 110 °C or higher.

14. The resin composition according to claim 1, wherein the number average molecular weight of the block copolymer I is 20,000 to 400,000.

15. The resin composition according to claim 1, wherein the number average molecular weight of the block structural unit B is 10,000 to 300,000.

16. The resin composition according to claim 1, wherein the block structural unit A contains a structural unit derived from poly-L-lactic acid or a structural unit derived from poly-D-lactic acid.

17. The resin composition according to claim 1, wherein relative to a total of 100% by mass of the block structural unit A and the block structural unit B, the block structural unit A is 5% by mass or more and 95% by mass or less.

18. A resin modifier comprising a block copolymer I, wherein the block copolymer I comprises a block structural unit A mainly composed of polylactic acid units a and a block structural unit B mainly composed of polyester units b, The polyester unit b contains units derived from an aliphatic diol b1 and an aliphatic dicarboxylic acid b2, The aliphatic diol b1 has an alkyl group as a side chain and does not have a quaternary carbon, The two hydroxyl groups of the aliphatic diol b1 are primary hydroxyl groups.

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