Biodegradable polyester resins, biodegradable polyester resin compositions, and molded articles thereof

Abstract

This invention provides biodegradable polyester resins, biodegradable polyester resin compositions, and molded articles thereof that have excellent biodegradability and excellent hydrolysis resistance. These biodegradable polyester resins, biodegradable polyester resin compositions, and molded articles thereof contain structural units derived from a dicarboxylic acid component (A) and structural units derived from an aliphatic diol component (B), and satisfy at least one of the following conditions (α) and (β). • Condition (α): The dicarboxylic acid component (A) contains a first dicarboxylic acid component (A1) composed of at least one compound selected from the group consisting of aliphatic dicarboxylic acids (a1) and their derivatives as shown in Formula (I). • Condition (β): The aliphatic diol component (B) contains a first aliphatic diol (B1) composed of at least one compound selected from the group consisting of aliphatic diols (b1) as shown in Formula (II). [The symbols in Formulas (I) and (II) are as defined in this application specification.]

Description

Technical Field

[0001] This invention relates to biodegradable polyester resins, biodegradable polyester resin compositions, and molded articles thereof. Background Technology

[0002] In recent years, environmental issues, exemplified by microplastics, have garnered significant attention. Common synthetic resins present the following problems: if left in the environment, they weather and pulverize due to ultraviolet radiation, but cannot completely decompose, leading to microplasticization and marine pollution. In recent years, the development of biodegradable plastics, often referred to as green plastics, has been underway. As synthetic resins, polyesters, polyvinyl alcohol-based resins, and polyamino acid resins are known, but currently, only polyesters can be practically melt-formed.

[0003] Biodegradable polyesters include aliphatic polyester resins such as polybutylene succinate and polybutylene adipate, aliphatic hydroxycarboxylic acid resins such as polylactic acid, and aromatic aliphatic copolyester resins such as polybutylene adipate. These biodegradable polyester resins exhibit excellent biodegradability, but their high decomposition rate results in poor storage stability, with the resin decomposing during storage. This decomposition is primarily caused by the hydrolysis of the polyester resin; therefore, hydrolysis-resistant agents are typically used in combination with these resins.

[0004] For example, Patent Document 1 proposes a structure that improves hydrolysis resistance by incorporating a hydrolysis-resistant agent into a polyester resin. Furthermore, Patent Document 2 proposes a method that improves hydrolysis resistance by introducing a special structure into a polyester resin.

[0005] On the other hand, in recent years, the requirements for the environmental adaptability of synthetic resins have become increasingly stringent, leading to the development of compositions that further enhance the biodegradability of conventional polyester resins. For example, Patent Document 3 demonstrates that by compounding polyhydroxyalkanoates into aliphatic polyester resins, the biodegradation rate at room temperature can be increased.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5279352

[0009] Patent Document 2: Japanese Patent Application Publication No. 10-130377

[0010] Patent Document 3: International Publication No. 2019 / 189367 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, according to the inventors' verification, it was found that in the proposals for improving hydrolysis resistance shown in Patent Documents 1 and 2, the biodegradation rate deteriorated, and the biodegradation rate could not be obtained sufficiently depending on the environment. Furthermore, it is known that in the proposal for improving the biodegradation rate shown in Patent Document 3, problems still exist, such as the inability to ensure the storage stability of the resin due to the significant deterioration of hydrolysis resistance.

[0013] The present invention addresses the aforementioned problems and aims to provide biodegradable polyester resins, biodegradable polyester resin compositions, and molded articles thereof that have excellent biodegradability and excellent hydrolysis resistance.

[0014] Methods for solving problems

[0015] In order to solve the above problems, in-depth research was conducted, and as a result, the inventors came up with the following invention, which was found to be able to solve the problem.

[0016] That is, the present invention includes the following inventions.

[0017] [1] A biodegradable polyester resin comprising structural units derived from a dicarboxylic acid component (A) and structural units derived from an aliphatic diol component (B), wherein the resin satisfies at least one of the following conditions (α) and (β).

[0018] • Condition (α): The above dicarboxylic acid component (A) contains a first dicarboxylic acid component (A1) consisting of at least one compound selected from the group consisting of aliphatic dicarboxylic acids (a1) and their derivatives shown in the following formula (I).

[0019] • Condition (β): The above-mentioned aliphatic diol component (B) contains a first aliphatic diol component (B1) composed of at least one compound selected from the aliphatic diols (b1) shown in the following formula (II).

[0020]

[0021] In equations (I) and (II), R 1 R 2 R 5 R 6 Each independently represents a divalent hydrocarbon group with 1 to 3 carbon atoms, R 3 R 7 Each independently represents a monovalent hydrocarbon group having 1 to 3 carbon atoms, R 4 R 8 Each of these groups independently represents a hydrogen atom or a monovalent hydrocarbon group with 1 to 3 carbon atoms; m, n, x, and y each independently represent 0 or 1.

[0022] [2] According to the biodegradable polyester resin described in [1] above, wherein the dicarboxylic acid component (A) contains the first dicarboxylic acid component (A1) and the second dicarboxylic acid component (A2), the second dicarboxylic acid component (A2) is composed of a compound selected from the group consisting of a second dicarboxylic acid (a2) different from the above aliphatic dicarboxylic acid (a1) and its derivatives, and the biodegradable polyester resin satisfies the following conditions (i) or (ii).

[0023] • Condition (i): The number of carbon atoms in the dicarboxylic acid contained in the second dicarboxylic acid component (A2) and the number of carbon atoms in the aliphatic diol component (B) are both 4 or less.

[0024] • Condition (ii): The second dicarboxylic acid component (A2) mentioned above contains an aromatic dicarboxylic acid.

[0025] [3] The biodegradable polyester resin according to [2] above, wherein the second dicarboxylic acid component (A2) contains an aromatic dicarboxylic acid.

[0026] [4] The biodegradable polyester resin according to any one of [1] to [3] above, wherein the content of the aliphatic dicarboxylic acid (a1) in the dicarboxylic acid component (A) is 2 to 60 mol.

[0027] [5] The biodegradable polyester resin according to any one of [1] to [4] above, wherein R in formula (I) 1 R 2 All are methylene.

[0028] [6] The biodegradable polyester resin according to any one of [1] to [5] above, wherein R in formula (I) 3 It is methyl, R 4 It is a hydrogen atom.

[0029] [7] The biodegradable polyester resin according to any one of [1] to [6] above, wherein the content of the first aliphatic diol component (B1) in the aliphatic diol component (B) is 2 to 50 mol.

[0030] [8] The biodegradable polyester resin according to any one of [1] to [7] above, wherein R in formula (II) 5 and R 6 It is a methylene group.

[0031] [9] The biodegradable polyester resin according to any one of [1] to [8] above, wherein R in formula (II) 7 It is methyl, R 8 It is a hydrogen atom.

[0032]

[10] The biodegradable polyester resin according to any one of [1] to [9] above, wherein the dicarboxylic acid component (A) does not contain aliphatic dicarboxylic acid (a2X) having branched chains and hydroxyl groups, or the content of the aliphatic dicarboxylic acid (a2X) in the dicarboxylic acid component (A) is greater than 0 mol% and less than 3 mol%.

[0033]

[11] The biodegradable polyester resin according to any one of [1] to

[10] above, wherein the dicarboxylic acid component (A) contains the first dicarboxylic acid component (A1), the second dicarboxylic acid component (A2) and the third dicarboxylic acid component (A3), wherein the second dicarboxylic acid component (A2) is composed of a compound selected from the group consisting of a second dicarboxylic acid (a2) different from the above aliphatic dicarboxylic acid (a1) and its derivatives, and wherein the third dicarboxylic acid component (A3) is composed of a compound selected from the group consisting of a third dicarboxylic acid (a3) ​​different from the above aliphatic dicarboxylic acid (a1) and the above second dicarboxylic acid (a2) and its derivatives.

[0034]

[12] According to the biodegradable polyester resin described in

[11] above, wherein the third dicarboxylic acid (a3) ​​is methyl succinic acid.

[0035]

[13] A biodegradable polyester resin composition comprising the biodegradable polyester resin described in any one of [1] to

[12] above and a hydrolysis resistant agent (C).

[0036]

[14] The biodegradable polyester resin composition according to

[13] above, wherein the hydrolysis resistant agent (C) is a carbodiimide compound.

[0037]

[15] The biodegradable polyester resin composition according to

[13] or

[14] above, wherein the content of the hydrolysis resistant agent (C) is 0.15 to 2 parts by weight relative to 100 parts by weight of the above biodegradable polyester resin.

[0038]

[16] A molded article comprising the biodegradable polyester resin described in any one of [1] to

[12] above or the biodegradable polyester resin composition described in any one of

[13] to

[15] above.

[0039]

[17] A membrane comprising the biodegradable polyester resin described in any one of [1] to

[12] above or the biodegradable polyester resin composition described in any one of

[13] to

[15] above.

[0040]

[18] A sheet comprising the biodegradable polyester resin described in any one of [1] to

[12] above or the biodegradable polyester resin composition described in any one of

[13] to

[15] above.

[0041]

[19] A food utensil comprising the biodegradable polyester resin described in any one of [1] to

[12] above or the biodegradable polyester resin composition described in any one of

[13] to

[15] above.

[0042]

[20] A plastic modifier comprising the biodegradable polyester resin described in any one of [1] to

[12] above or the biodegradable polyester resin composition described in any one of

[13] to

[15] above.

[0043]

[21] A coating agent comprising the biodegradable polyester resin described in any one of [1] to

[12] above or the biodegradable polyester resin composition described in any one of

[13] to

[15] above.

[0044] Invention Effects

[0045] According to the present invention, it is possible to provide biodegradable polyester resins, biodegradable polyester resin compositions, and molded articles thereof that have excellent biodegradability and excellent hydrolysis resistance. Attached Figure Description

[0046] Figure 1 This is an example of a photograph showing the appearance of a polyester resin film after a compostability evaluation.

[0047] Figure 2 This is an example of the appearance of other polyester resin films after compostability evaluation.

[0048] Figure 3 This is an example of a photograph showing the appearance of a polyester resin film after a hydrolysis resistance evaluation.

[0049] Figure 4 This is an example of the appearance of other polyester resin films after hydrolysis resistance evaluation. Detailed Implementation

[0050] The following description is based on an example of an embodiment of the present invention. However, the embodiments shown below are merely illustrative examples used to concretize the technical concept of the present invention, and the present invention is not limited to the following description.

[0051] Furthermore, while preferred embodiments are shown in this specification, combinations of two or more preferred embodiments are also preferred. Regarding the numerical ranges, when there are several numerical ranges, their lower and upper limits can be selectively combined to form preferred embodiments.

[0052] It should be noted that in this specification, when a numerical range such as "XX~YY" is recorded, it means "above XX and below YY".

[0053] [Biodegradable polyester resin]

[0054] The biodegradable polyester resin of the present invention is a biodegradable polyester resin containing structural units derived from dicarboxylic acid component (A) and structural units derived from aliphatic diol component (B), and satisfies at least one of the following conditions (α) and (β).

[0055] • Condition (α): The above dicarboxylic acid component (A) contains a first dicarboxylic acid component (A1) consisting of at least one compound selected from the group consisting of aliphatic dicarboxylic acids (a1) and their derivatives shown in the following formula (I).

[0056] • Condition (β): The above-mentioned aliphatic diol component (B) contains a first aliphatic diol component (B1) composed of at least one compound selected from the aliphatic diols (b1) shown in the following formula (II).

[0057]

[0058] In equations (I) and (II), R 1 R 2 R 5 R 6 Each independently represents a divalent hydrocarbon group with 1 to 3 carbon atoms, R 3 R 7 Each independently represents a monovalent hydrocarbon group having 1 to 3 carbon atoms, R 4 R 8 Each of these groups independently represents a hydrogen atom or a monovalent hydrocarbon group with 1 to 3 carbon atoms; m, n, x, and y each independently represent 0 or 1.

[0059] The aliphatic dicarboxylic acid (a1) shown in formula (I) and the aliphatic diol (b1) shown in formula (II) above have branched structures. Therefore, it is believed that by making the dicarboxylic acid component (A) contain a first dicarboxylic acid component (A1) composed of at least one compound selected from the group consisting of the above-mentioned aliphatic dicarboxylic acid (a1) and its derivatives, or by making the aliphatic diol component (B) contain a first aliphatic diol component (B1) composed of at least one compound selected from the above-mentioned aliphatic diol (b1), the crystallinity of the obtained biodegradable polyester resin is reduced and its biodegradability is easily improved.

[0060] On the other hand, it is believed that due to the branched structure of aliphatic dicarboxylic acids (a1) and their derivatives, the branched structure of aliphatic diols (b1), or both, the decomposition reaction of the above-mentioned biodegradable polyester resin is inhibited due to steric hindrance, which can improve hydrolysis resistance while maintaining biodegradability.

[0061] It is speculated that the aforementioned biodegradable polyester resin can balance excellent biodegradability and excellent hydrolysis resistance. This biodegradable polyester resin exhibits high environmental adaptability and storage stability due to its good biodegradability and hydrolysis resistance.

[0062] In this specification, "biodegradability" refers to the property of being able to be ultimately decomposed into water and carbon dioxide by microorganisms or the like, including the observed reduction in mass when stored in a composting environment for a certain period of time. Therefore, in this specification, "biodegradability" is sometimes referred to as "compostability".

[0063] From the viewpoint of exhibiting good biodegradability, when the biodegradable polyester resin of the embodiments of the present invention is subjected to a composting test in accordance with JIS K6954:2008, the weight of the resin or resin composition before the test and 30 days later is measured. The weight retention rate after the test is preferably 85% or less, more preferably 70% or less, further preferably 50% or less, and even more preferably 40% or less. A lower limit of 0% for the weight retention rate is ideal, but even a value of 20% or more is sufficient to meet the required performance. In other words, the weight retention rate of the above-mentioned biodegradable polyester resin after the above-mentioned composting test is preferably 0 to 85%, and may also be 20 to 85%.

[0064] The biodegradable polyester resin of the preferred embodiment of the present invention is a biodegradable polyester resin as follows: the dicarboxylic acid component (A) contains the first dicarboxylic acid component (A1) and the second dicarboxylic acid component (A2), wherein the second dicarboxylic acid component (A2) is composed of a compound selected from the group consisting of a second dicarboxylic acid (a2) different from the above-mentioned aliphatic dicarboxylic acid (a1) and its derivatives, and the biodegradable polyester resin satisfies the following conditions (i) or (ii).

[0065] • Condition (i): The number of carbon atoms in the dicarboxylic acid contained in the second dicarboxylic acid component (A2) and the number of carbon atoms in the aliphatic diol component (B) are both 4 or less.

[0066] • Condition (ii): The second dicarboxylic acid component (A2) mentioned above contains an aromatic dicarboxylic acid.

[0067] The biodegradable polyester resin of the above embodiments can be easily endowed with other properties such as mechanical properties by making the dicarboxylic acid component (A) also contain the second dicarboxylic acid component (A2).

[0068] It should be noted that, as described above, compared to the case where the dicarboxylic acid component (A) is only the second dicarboxylic acid component (A2), it can also be regarded as replacing at least a portion of the second dicarboxylic acid component (A2) with the first dicarboxylic acid component (A1). Therefore, the biodegradable polyester resin of this embodiment is sometimes described as "a substance obtained by modifying the dicarboxylic acid component (A) with the first dicarboxylic acid component (A1)".

[0069] The following describes in detail the components used to obtain the above-mentioned biodegradable polyester resin, the biodegradable polyester resin and the biodegradable polyester resin composition, and their molded articles.

[0070] It should be noted that, in order to avoid the repetition of ingredient names and make the text lengthy, for example, "dicarboxylic acid component (A)" will sometimes be abbreviated as "component (A)".

[0071] <Dicarboxylic acid component (A)>

[0072] The dicarboxylic acid component (A) contains a first dicarboxylic acid component (A1) composed of an aliphatic dicarboxylic acid (a1) as shown in the above formula (I).

[0073] The preferred dicarboxylic acid component (A) contains the aforementioned first dicarboxylic acid component (A1) and second dicarboxylic acid component (A2), wherein the second dicarboxylic acid component (A2) is composed of a compound selected from the group consisting of a second dicarboxylic acid (a2) different from aliphatic dicarboxylic acids (a1) and its derivatives.

[0074] (First dicarboxylic acid component (A1))

[0075] The first dicarboxylic acid component (A1) is composed of at least one compound selected from the group consisting of aliphatic dicarboxylic acids (a1) and their derivatives as shown in formula (I) below. It should be noted that in the following description, the aliphatic dicarboxylic acid (a1) shown in formula (I) is sometimes simply referred to as "aliphatic dicarboxylic acid (a1)".

[0076]

[0077] In equation (I), R 1 R 2 Each of these groups independently represents a divalent hydrocarbon group with 1 to 3 carbon atoms.

[0078] As R 1 and R 2The divalent hydrocarbon groups representing 1 to 3 carbon atoms can be exemplified by methylene, ethylene, trimethylene, and methyl ethylene.

[0079] In equation (I), m and n independently represent 0 or 1.

[0080] From the perspective of balancing biodegradation rate and hydrolysis resistance, it is preferable that m and n are both 1, and R in equation (I) is... 1 R 2 All are methylene.

[0081] In equation (I), R 3 It represents a monovalent hydrocarbon group with 1 to 3 carbon atoms.

[0082] In equation (I), R 4 A monovalent hydrocarbon group representing 1 to 3 hydrogen or carbon atoms.

[0083] As R 3 R 4 The monovalent hydrocarbon group representing 1 to 3 carbon atoms can be methyl, ethyl, 1-propyl, or 2-propyl. Among these, methyl is preferred from the viewpoint of easily possessing moderate steric hindrance.

[0084] In one approach, R in equation (I) 3 It is methyl, R 4 The aliphatic dicarboxylic acid (a1) and its derivatives tend to exhibit moderate steric hindrance.

[0085] Examples of aliphatic dicarboxylic acids (a1) include 3-methylpentanediic acid (also known as 3-methylglutaric acid), methylsuccinic acid, methylmalonic acid, 2-methylglutaric acid, propylsuccinic acid, 3-ethylglutaric acid, 2-ethylglutaric acid, 3-propylglutaric acid, 2-propylglutaric acid, propylpropanediic acid (also known as propylmalonic acid), ethylpropanediic acid (also known as ethylmalonic acid), 2-methylhexanoic acid, and 3-methylhexanoic acid. Among these, 3-methylpentanediic acid is preferred from the viewpoint of reduced crystallinity and steric hindrance.

[0086] Examples of derivatives of aliphatic dicarboxylic acids (a1) include anhydrides of the aforementioned aliphatic dicarboxylic acids (a1), ester compounds of the aforementioned aliphatic dicarboxylic acids (a1), and acyl halides of the aforementioned aliphatic dicarboxylic acids (a1).

[0087] Examples of acid anhydrides that are aliphatic dicarboxylic acids (a1) include 3-methylpentanediic anhydride, 2-methylglutarylic anhydride, and methylsuccinic anhydride.

[0088] As the ester compound of the aforementioned aliphatic dicarboxylic acid (a1), a dialkyl ester of the aforementioned aliphatic dicarboxylic acid (a1) is preferred. As the dialkyl ester, a dimethyl ester or a diethyl ester of the aforementioned aliphatic dicarboxylic acid (a1) is preferred.

[0089] As the acyl halide of the aforementioned aliphatic dicarboxylic acid (a1), the dihalide of the aforementioned aliphatic dicarboxylic acid (a1) is preferred. As the halogen atom constituting the aforementioned acyl halide, chlorine atom and bromine atom are preferred.

[0090] The aforementioned aliphatic dicarboxylic acids (a1) and their derivatives can be used alone or in combination with more than one type. From the viewpoint of easily achieving the desired properties, it is preferred to use one type alone.

[0091] (Second dicarboxylic acid component (A2))

[0092] As described above, the dicarboxylic acid component (A) used to obtain the biodegradable polyester resin of the preferred embodiment of the present invention contains the first dicarboxylic acid component (A1) and the second dicarboxylic acid component (A2) described above, wherein the second dicarboxylic acid component (A2) is composed of a compound selected from the group consisting of a second dicarboxylic acid (a2) different from aliphatic dicarboxylic acid (a1) and its derivatives.

[0093] The aforementioned second dicarboxylic acid (a2) can be an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, or an aromatic dicarboxylic acid. More preferably, it is an aliphatic dicarboxylic acid or an aromatic dicarboxylic acid.

[0094] Examples of second dicarboxylic acids (a2) include: aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, and sebacic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Among these, succinic acid, adipic acid, and terephthalic acid are preferred.

[0095] As derivatives of the second dicarboxylic acid (a2), examples include the acid anhydrides of the aforementioned aliphatic dicarboxylic acids, the ester compounds of the aforementioned aliphatic dicarboxylic acids, the acyl halides of the aforementioned aliphatic dicarboxylic acids, the acid anhydrides of the aforementioned alicyclic dicarboxylic acids, the ester compounds of the aforementioned alicyclic dicarboxylic acids, the acyl halides of the aforementioned alicyclic dicarboxylic acids, the acid anhydrides of the aforementioned aromatic dicarboxylic acids, the ester compounds of the aforementioned aromatic dicarboxylic acids, and the acyl halides of the aforementioned aromatic dicarboxylic acids.

[0096] From the viewpoint of easily improving the softness of biodegradable polyester resin, the above-mentioned second dicarboxylic acid component (A2) preferably contains an aromatic dicarboxylic acid.

[0097] These can be used individually or in combination with more than one type.

[0098] When the dicarboxylic acid component (A) contains a second dicarboxylic acid component (A2), it is preferable that the number of carbon atoms of the dicarboxylic acid component (A2) and the number of carbon atoms of the aliphatic diol component (B) are both 4 or less, as specified in condition (i) above, or that the second dicarboxylic acid component (A2) contains an aromatic dicarboxylic acid, as specified in condition (ii) above.

[0099] As a dicarboxylic acid with 4 or fewer carbon atoms as specified in condition (i) above, examples include succinic acid, malonic acid, and oxalic acid, with succinic acid being preferred.

[0100] When the total mass of the dicarboxylic acid component (A) is set to 100% by mass, the total mass of the first dicarboxylic acid component (A1) and the second dicarboxylic acid component (A2) in the dicarboxylic acid component (A) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. There is no particular upper limit; it can be 100% by mass or less, 98% by mass or less, or 95% by mass or less. In other words, the total mass of the first dicarboxylic acid component (A1) and the second dicarboxylic acid component (A2) in the dicarboxylic acid component (A) is preferably 80 to 100% by mass.

[0101] From the viewpoint of easily improving biodegradability and hydrolysis resistance, the content (or modification rate) of the aliphatic dicarboxylic acid (a1) in the dicarboxylic acid component (A), in other words, the content (or modification rate) of the first dicarboxylic acid component (A1) in the dicarboxylic acid component (A) is preferably 2 to 80 mol%, more preferably 2 to 70 mol%, even more preferably 2 to 60 mol%, even more preferably 3 to 60 mol%, and particularly preferably 3 to 58 mol%.

[0102] From the viewpoint that biodegradable polyester resins tend to have a suitable molecular weight, the dicarboxylic acid component (A) preferably does not contain aliphatic dicarboxylic acids (a2X) having branched chains and hydroxyl groups as the second dicarboxylic acid component (A2), or the content of the aliphatic dicarboxylic acid (a2X) in the dicarboxylic acid component (A) is greater than 0 mol% and less than 3 mol%.

[0103] Examples of the aforementioned aliphatic dicarboxylic acids (a2X) include, for instance, 3-hydroxy-3-methylglutaric acid.

[0104] In the biodegradable polyester resin of a preferred embodiment of the present invention, the dicarboxylic acid component (A) may contain the first dicarboxylic acid component (A1), the second dicarboxylic acid component (A2), and the third dicarboxylic acid component (A3), wherein the third dicarboxylic acid component (A3) is composed of a compound selected from the group consisting of a third dicarboxylic acid (a3) ​​and its derivatives that are different from the above-mentioned aliphatic dicarboxylic acids (a1) and the second dicarboxylic acid (a2).

[0105] Examples of the aforementioned third dicarboxylic acid (a3) ​​include 2-methylsuccinic acid.

[0106] <Aliphatic diol component (B)>

[0107] The aliphatic diol component (B) contains a first aliphatic diol component (B1) consisting of at least one compound selected from the aliphatic diols (b1) shown in formula (I).

[0108] The preferred aliphatic diol component (B) contains the first aliphatic diol component (B1) and a second diol component (B2) composed of a compound selected from a second diol (b2) different from the aliphatic diol (b1).

[0109] (First aliphatic diol component (B1))

[0110] The first aliphatic diol component (B1) is composed of at least one compound selected from the aliphatic diols (b1) shown in formula (II) below. It should be noted that in the following description, the aliphatic diol (b1) shown in formula (II) is sometimes simply referred to as "aliphatic diol (b1)".

[0111]

[0112] In equation (I), R 5 R 6 Each of these groups independently represents a divalent hydrocarbon group with 1 to 3 carbon atoms.

[0113] As R 5 and R 6 The divalent hydrocarbon group representing 1 to 3 carbon atoms can be exemplified by methylene, ethylene, trimethylene, and methyl ethylene. R is preferred. 5 and R 6 It is a methylene group.

[0114] In equation (II), x and y each independently represent 0 or 1.

[0115] From the perspective of balancing biodegradation rate and hydrolysis resistance, it is preferable that both x and y are 1, and that R in equation (I) is... 5 R 6 All are methylene.

[0116] In equation (II), R 7 It represents a monovalent hydrocarbon group with 1 to 3 carbon atoms.

[0117] In equation (II), R 8 A monovalent hydrocarbon group representing 1 to 3 hydrogen or carbon atoms.

[0118] As R 7 R 8 The monovalent hydrocarbon group representing 1 to 3 carbon atoms can be methyl, ethyl, 1-propyl, or 2-propyl. Among these, methyl is preferred from the viewpoint of easily possessing moderate steric hindrance.

[0119] In one approach, R in equation (II) 7 It is methyl, R 8 The aliphatic diol (b1) is a hydrogen atom. In this case, the aliphatic diol (b1) tends to exhibit moderate steric hindrance.

[0120] Examples of aliphatic diols (b1) include propylene glycol, 2-methyl-1,3-propanediol, 1,3-butanediol, 2-methyl-1,4-butanediol, 2-isopropyl-1,4-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 2,7-dimethyl-1,8-octanediol, 2-methyl-1,9-nonanediol, 2,8-dimethyl-1,9-nonanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, and neopentanediol. Among these, 3-methyl-1,5-pentanediol is preferred from the viewpoint of reduced crystallinity and steric hindrance.

[0121] The aforementioned aliphatic diol (b1) can be used alone or in combination with more than one type. From the viewpoint of easily achieving the desired properties, it is preferred to use one type alone.

[0122] (Second diol component (B2))

[0123] As described above, the aliphatic diol component (B) used to obtain the biodegradable polyester resin of the preferred embodiment of the present invention contains the first aliphatic diol component (B1) and a second diol component (B2) composed of a compound selected from a second diol (b2) different from the aliphatic diol (b1).

[0124] The second diol (b2) mentioned above can be an aliphatic diol or an alicyclic diol.

[0125] Examples of the second diol (b2) include: ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and other aliphatic diols; and cyclohexanediol, etc. Ethylene glycol and 1,4-butanediol are preferred.

[0126] These can be used individually or in combination with more than one type.

[0127] When the aliphatic diol component (B) contains a second diol component (B2), it is preferable that the number of carbon atoms in the aliphatic diol (b1) as the first aliphatic diol component (B1) and the number of carbon atoms in the second diol (b2) as the second diol component (B2) are 6 or less. Furthermore, when the aliphatic diol component (B) contains a second diol component (B2) and the dicarboxylic acid component (A) contains a second dicarboxylic acid component (A2), it is preferable that the number of carbon atoms in the dicarboxylic acid component (A2) is 4 or less, as specified in condition (i) above, or that the number of carbon atoms in the dicarboxylic acid component (A2) is 6 or less, as specified in condition (ii) above.

[0128] Examples of diols with 4 or fewer carbon atoms include ethylene glycol, 1,3-propanediol, and 1,4-butanediol, with butanediol being the most preferred.

[0129] When the total mass of the aliphatic diol component (B) is set to 100% by mass, the total mass of the first aliphatic diol component (B1) and the second aliphatic diol component (B2) in the aliphatic diol component (B) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. There is no particular upper limit; it can be 100% by mass or less, 98% by mass or less, or 95% by mass or less. In other words, the total mass of the first aliphatic diol component (B1) and the second aliphatic diol component (B2) in the aliphatic diol component (B) is preferably 80 to 100% by mass.

[0130] From the viewpoint of easily improving biodegradability and hydrolysis resistance, the content (or modification rate) of the aliphatic diol (b1) in the aliphatic diol component (B), in other words, the content (or modification rate) of the first aliphatic diol component (B1) in the aliphatic diol component (B) is preferably 2 to 80 mol%, more preferably 2 to 70 mol%, even more preferably 2 to 60 mol%, even more preferably 3 to 60 mol%, and particularly preferably 2 to 50 mol%.

[0131] <Content of structural units derived from components (A) and (B) in the resin>

[0132] From the viewpoint of easily ensuring good biodegradability and hydrolysis resistance, when the mass of the biodegradable polyester resin is set to 100% by mass, the total mass content of the structural units derived from dicarboxylic acid component (A) and the structural units derived from aliphatic diol component (B) in the biodegradable polyester resin of this embodiment is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more. There is no particular upper limit; it can be 100% by mass or less, 95% by mass or less, or 90% by mass or less. In other words, the total mass ratio of the structural units derived from dicarboxylic acid component (A) and the structural units derived from aliphatic diol component (B) in the biodegradable polyester resin of this embodiment is preferably 70 to 100% by mass.

[0133] (Other ingredients)

[0134] The biodegradable polyester resin of this embodiment may contain other components.

[0135] Other components mentioned above may include inorganic fillers, softeners, heat aging resistant agents, antioxidants, light stabilizers, antistatic agents, release agents, flame retardants, foaming agents, pigments, dyes, whitening agents, ultraviolet absorbers, lubricants, plasticizers, crosslinking agents, fillers, crosslinking accelerators, crosslinking aids, adhesion promoters, bonding agents, organic fillers, nucleating agents, heat stabilizers, colorants, flame retardant additives, anti-blooming agents, thickeners, conductive additives, and flow improvers. However, the hydrolysis resistant agent (C) described later is not included among the other components that may be contained in biodegradable polyester resins.

[0136] They can be used individually or in combination of two or more.

[0137] The content of the other components mentioned above can be appropriately determined according to the desired physical properties of the biodegradable polyester resin. From the viewpoint of easily achieving the desired performance of the biodegradable polyester resin, when the biodegradable polyester resin is set to 100% by mass, it is preferably 0.001 to 30% by mass, more preferably 0.005 to 25% by mass, even more preferably 0.07 to 20% by mass, even more preferably 0.01 to 15% by mass, even more preferably 0.01 to 10% by mass, and particularly preferably 0.01 to 5% by mass.

[0138] Properties of Biodegradable Polyester Resins

[0139] (Biodegradable)

[0140] As described above, when composting tests are conducted on biodegradable polyester resins in accordance with JIS K6954:2008, the weight retention rate after the test is preferably 0 to 85% or less when measuring the weight of the resin or resin composition before and after the test.

[0141] (Number average molecular weight (Mn))

[0142] From the viewpoint of strength and operability, the Mn of the above-mentioned biodegradable polyester resin is preferably 2,000 to 100,000, more preferably 3,000 to 80,000, even more preferably 4,000 to 60,000, and even more preferably 5,000 to 50,000.

[0143] In this specification, the Mn of the biodegradable polyester resin is the number-average molecular weight converted from standard polymethyl methacrylate (PMMA) resin determined by size exclusion high performance liquid chromatography, specifically by the method described in the examples.

[0144] (weight-average molecular weight (Mw))

[0145] From the viewpoint of strength and operability, the Mw of the biodegradable polyester resin is preferably 5,000 to 200,000, more preferably 10,000 to 150,000, even more preferably 15,000 to 120,000, and even more preferably 20,000 to 100,000.

[0146] In this specification, the Mw of the biodegradable polyester resin is the number-average molecular weight converted from standard polymethyl methacrylate (PMMA) resin determined by size exclusion high performance liquid chromatography, specifically, determined by the method described in the examples.

[0147] (Intrinsic viscosity of solution (IV))

[0148] From the viewpoint of easily obtaining a suitable molecular weight, the intrinsic viscosity (IV) of the solution of the biodegradable polyester resin at 30°C is preferably 0.90 to 1.05 dl / g, more preferably 0.91 to 1.04 dl / g, and even more preferably 0.92 to 1.03 dl / g.

[0149] The IV above was determined using the method described in the examples.

[0150] (Elongation at break)

[0151] From the viewpoint of ensuring good flexibility, a high elongation at break is desirable for the biodegradable polyester resin, preferably 200% or more, more preferably 300% or more, further preferably 400% or more, and even more preferably 500% or more. There is no particular limitation on the upper limit of the above elongation at break, but from the viewpoint of strength, it is, for example, 1000% or less, 900% or less, or 800% or less. In other words, the elongation at break of the biodegradable polyester resin is preferably 200 to 1000%.

[0152] Depending on the application, if high flexibility is not required for the biodegradable polyester resin, the elongation at break of the biodegradable polyester resin may be, for example, 10–100%, 12–70%, or 13–50%.

[0153] The elongation at break was determined using the method described in the examples.

[0154] (Hydrolysis resistance)

[0155] For biodegradable polyester resins, from the viewpoint of easily improving storage stability, it is preferable to have the highest possible hydrolysis resistance, specifically the molecular weight retention rate after immersing the biodegradable polyester resin of a predetermined shape in hot water for a predetermined time. More specifically, when a material processed from biodegradable polyester resin into a film shape of a predetermined size is immersed in hot water at 80°C, the molecular weight retention rate after 4 days is preferably 76% or more, more preferably 78% or more, and even more preferably 80% or more; the molecular weight retention rate after 7 days is preferably 55% or more, more preferably 58% or more, and even more preferably 60% or more. The upper limit of the molecular weight retention rate after 4 days and 7 days can be 100%, 95%, or 90%. In other words, the hydrolysis resistance (after 4 days) of the biodegradable polyester resin is preferably 80-100%, and the hydrolysis resistance (after 7 days) is preferably 60-100%.

[0156] Hydrolysis resistance was determined using the methods described in the examples.

[0157] <Manufacturing Method of Biodegradable Polyester Resin>

[0158] The method for manufacturing the polyester of the present invention is not particularly limited, and known polyester polycondensation methods can be applied. For example, 3-methylpentanediol or its derivatives and diol components are added in a prescribed ratio, and esterification or transesterification is carried out, so that the reaction product is further polycondensed under high temperature and vacuum in the presence of a polycondensation catalyst, thereby producing a polyester with a desired molecular weight. It should be noted that a wide range of polycondensation catalysts can be used as polycondensation catalysts in the manufacture of polyester. Examples of such polycondensation catalysts include: titanium compounds such as tetramethoxytitanium, tetraethoxytitanium, tetran-propoxytitanium, tetraisopropoxytitanium, and tetrabutoxytitanium; tin compounds such as di-n-butyltin oxide, di-n-butyltin dilaurate, and dibutyltin diacetate; and combinations of acetates of magnesium, calcium, zinc, etc., with antimony oxide or the above-mentioned titanium compounds. These polycondensation catalysts are preferably used in the range of 5 to 500 ppm by mass relative to the total amount of polyester produced.

[0159] The molar ratio of the dicarboxylic acid component (A) MA to the aliphatic diol component (B) MB used in the above-mentioned polycondensation reaction is preferably 0.8:1.0 to 1.0:0.8, more preferably 0.9:1.0 to 1.0:0.9, and even more preferably 0.95:1.0 to 1.0:0.95. It should be noted that when the dicarboxylic acid component (A) and the aliphatic diol component (B) are each composed of two or more compounds, the above molar amounts are the arithmetic mean of the molar amounts of these two or more compounds.

[0160] [Biodegradable polyester resin composition]

[0161] The biodegradable polyester resin composition of the present invention contains the above-mentioned biodegradable polyester resin and a hydrolysis-resistant agent (C). By containing the hydrolysis-resistant agent (C), the hydrolysis reaction of the above-mentioned biodegradable polyester resin composition is suppressed, and good durability is easily obtained.

[0162] Relative to 100% of the total mass of the biodegradable polyester resin composition, the content of biodegradable polyester resin in the above-mentioned biodegradable polyester resin composition is preferably 35 to 99.8% by mass, more preferably 45 to 99.5% by mass, and even more preferably 50 to 99% by mass.

[0163] <Hydrolysis-resistant agent (C)>

[0164] As for hydrolysis resistant agent (C), there are no particular restrictions as long as the component has the property of preventing hydrolysis, and known hydrolysis resistant agents can be used.

[0165] As an example of the aforementioned hydrolysis-resistant agent (C), those containing, for example, [are...] Compounds with an oxolinyl group ( Compounds include zozoline compounds, compounds containing epoxy groups (epoxide compounds), and compounds containing carbodiimide groups (carbodiimide compounds). Among these, from the viewpoint of hydrolysis resistance and formability, the hydrolysis-resistant agent (C) is preferably a carbodiimide compound.

[0166] Examples of the aforementioned carbodiimide compounds include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, diphenylcarbodiimide, di-tert-butylcarbodiimide, di-β-naphthylcarbodiimide, polycarbodiimide, and cyclic carbodiimides.

[0167] The aforementioned polycarbodiimide is a compound formed by two or more carbodiimide groups bonded together by a bonding group consisting of an aliphatic group, an alicyclic group, an aromatic group, or a combination thereof.

[0168] The aforementioned cyclic carbodiimide is a compound having one or more carbodiimide groups within its molecular structure, and forming a ring structure by bonding the first nitrogen atom of the carbodiimide group to the second nitrogen atom through a bonding group composed of an aliphatic group, an alicyclic group, an aromatic group, or a combination thereof. The bonding group may contain heteroatoms or substituents.

[0169] The above-mentioned hydrolysis resistant agent (C) can be used in one or more ways.

[0170] From the viewpoint of easily improving hydrolysis resistance while maintaining good biodegradability, the content of hydrolysis resistant agent (C) is preferably 0.15 to 2 parts by mass relative to 100 parts by mass of the above-mentioned biodegradable polyester resin, more preferably 0.15 to 1.8 parts by mass, further preferably 0.18 to 1.5 parts by mass, and even more preferably 0.18 to 1.2 parts by mass.

[0171] <Other Resins>

[0172] The biodegradable polyester resin composition of the embodiments of the present invention may contain resins other than the above-mentioned biodegradable polyester resins, for example, it may contain biomass resins or biodegradable resins.

[0173] Examples of such biomass resins or biodegradable resins include polylactic acid (PLA), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene adipate succinate (PBSA), polybutylene adipate terephthalate (PBAT), polyglycolic acid (PGA), polyethylene furanate (PEF), polyhydroxyalkanoates (PHA) [e.g., polyhydroxybutyrate valerate (PHBV), 3-hydroxybutyrate-3-hydroxyhexanoate copolyester, etc.], cellulose acetate (CA), starch, and other polysaccharides. They may also contain biodegradable polymers such as 3-hydroxybutyrate-based polymers and β-methyl-δ-valerol-based polymers.

[0174] From the viewpoint of effectively obtaining the effects of the present invention, the content of the other resins in the biodegradable polyester resin composition is preferably less than 50 parts by weight, more preferably 40 parts by weight or less, and even more preferably 30 parts by weight or less, relative to a total of 100 parts by weight of the biodegradable polyester resin and the other resins. There is no particular limitation on the lower limit; for example, it is 5 parts by weight or more. In other words, the content of the other resins is preferably 5 parts by weight or more and less than 50 parts by weight, relative to a total of 100 parts by weight of the biodegradable polyester resin and the other resins.

[0175] <Other Additives>

[0176] The additives (hereinafter referred to as "other additives") that may be contained in the biodegradable polyester resin composition according to embodiments of the present invention, other than the hydrolysis resistant agent (C), may be substances listed in the other components that may be contained in the above-mentioned biodegradable polyester resin.

[0177] Regarding the content of additives other than the hydrolysis resistant agent (C) in the above-mentioned biodegradable polyester resin composition, it can be appropriately determined according to the desired physical properties of the biodegradable polyester resin composition. From the viewpoint of easily achieving the desired performance of the biodegradable polyester resin composition, when the above-mentioned biodegradable polyester resin composition is set to 100% by mass, it is preferably 0.001 to 30% by mass, more preferably 0.005 to 25% by mass, even more preferably 0.007 to 20% by mass, even more preferably 0.01 to 15% by mass, even more preferably 0.01 to 10% by mass, and particularly preferably 0.01 to 5% by mass.

[0178] <Properties of Biodegradable Polyester Resin Compositions>

[0179] The terms “biodegradability,” “elongation at break,” and “hydrolysis resistance” for the biodegradable polyester resin composition are the same as those for the various physical properties of the biodegradable polyester resin.

[0180] That is, regarding the biodegradability of the biodegradable polyester resin composition, when conducting composting tests in accordance with JIS K6954:2008, the weight retention rate after the test when measuring the weight of the resin or resin composition before and after the test is preferably 0 to 85% or less.

[0181] In addition, regarding the elongation at break of the biodegradable polyester resin composition, it is preferably 200 to 1000% when high softness is required, and for example 10 to 100% when high softness is not required.

[0182] Furthermore, regarding the hydrolysis resistance of the biodegradable polyester resin composition, the hydrolysis resistance, defined by the molecular weight retention rate after immersing the above-mentioned biodegradable polyester resin having a specified shape in hot water for a specified time, is preferably 80 to 100% (after 4 days), and more preferably 60 to 100% (after 7 days).

[0183] <Method for manufacturing biodegradable polyester resin compositions>

[0184] The method for manufacturing the biodegradable polyester resin composition of this embodiment is not particularly limited; it is sufficient to uniformly mix the biodegradable polyester resin, the hydrolysis resistant agent (C), and any necessary additives.

[0185] Examples of mixing methods include melt mixing using single-screw extruders, multi-screw extruders, Banbury internal mixers, heated rollers, Brabender mixers, various kneaders, etc., or melt mixing by supplying each component from its respective feed port.

[0186] Alternatively, premixing can be performed before melt mixing. Examples of premixing methods include using Henschel mixers, high-speed mixers, V-type mixers, ribbon mixers, drum mixers, and conical mixers.

[0187] Considering the melting point and decomposition temperature of biodegradable polyester resin, the temperature during melt mixing can preferably be arbitrarily selected within the range of 130 to 200°C.

[0188] [molded body]

[0189] The molded articles of embodiments of the present invention comprise the above-described biodegradable polyester resin or the above-described biodegradable polyester resin composition.

[0190] The shape of the molded body described above can be any shape that can be manufactured using the aforementioned biodegradable polyester resin or the aforementioned biodegradable polyester resin composition. Examples of molded bodies include granules, films, sheets, plates, pipes, hoses, bottles, fibrous bodies, rods, microparticles, granular bodies, foams, and various other shapes. There are no particular limitations on the manufacturing method of this molded body; it can be formed using various molding methods, such as injection molding, blow molding, compression molding, extrusion molding, calendering, and molding using a 3D printer, or other known methods.

[0191] When the above-mentioned molded body is a film, its thickness is, for example, 5-500 μm, 25-300 μm or 50-200 μm.

[0192] [use]

[0193] The biodegradable polyester resin, biodegradable polyester resin composition, and their molded articles according to this embodiment can be used for a variety of applications.

[0194] Examples of uses for the above-mentioned biodegradable polyester resins, biodegradable polyester resin compositions, and molded articles thereof include: Food packaging bags, bottle caps, trays, straws, tableware, food containers, coffee capsules, bottles, and other disposable or reusable food utensils; Stoppers and bottle cap liners for containers used to store food, beverages, medicine, etc. Packaging materials for electronic components, pharmaceuticals, food packaging films, agricultural materials such as multi-layer films or compost bags, civil and building materials, and industrial materials, including single-layer or multi-layer films and sheets. Daily necessities such as seedling trays, cosmetic containers, detergent containers, bleach containers, shopping bags or garbage bags; laminated films, boards, stretch sheets, sanitary covering materials, outdoor leisure products, water-retaining sheets, refrigerators, cushioning films, synthetic paper and other industrial materials. Fibers such as fishing lines, fishing nets, vegetation nets, monofilaments, flat yarns, short fibers, crimped fibers, ribbed strips, split-film yarns, ropes, binding materials, composite fibers, fabrics, and non-woven fabrics; Solvent-based, hot-melt, and thermo-stretchable adhesives and bonding agents; Water-based, solution-based, emulsion-based, and dispersion-based coatings; Medical materials such as surgical sutures, artificial bones, artificial skin, microcapsules and other DDS, and wound covering materials; 3D printer filaments; Toner for developing; Support materials used in hydraulic fracturing and leak-proof agents used during excavation; Vibration damping rubber, floor mats, seats, cushions, shock absorbers, pads, mounting rubber and other various vibration damping components; Components such as casings for household appliances such as televisions, stereos, vacuum cleaners, and refrigerators, or mobile phones; Interior and exterior automotive components such as bumper parts, body panels, windshield strips, cable guards, dashboard panels, and airbag covers; Various handles for scissors, screwdrivers, toothbrushes, ski poles, etc.; Plastic modifiers; etc.

[0195] Example

[0196] The present invention will now be described in more detail by way of examples, but the present invention is not limited to these examples in any way.

[0197] [Calculation of content]

[0198] Using the Avance600 nuclear magnetic resonance spectrometer manufactured by NEC Corporation, the determination of polyester resins was performed at 323 K using trifluoroacetic acid solvent. 1 H-NMR, calculate the content of aliphatic dicarboxylic acids (a1) and their derivatives according to the following formula (F1).

[0199] Ratio (mol%) of aliphatic dicarboxylic acids (a1) and their derivatives

[0200] =(Integral value of aliphatic dicarboxylic acid (a1) / number of protons) × 100 / [(Integral value of aliphatic dicarboxylic acid (a1) / number of protons) + (Integral value of the second dicarboxylic acid (a2) / number of protons)] … Equation (F1)

[0201] In the above formula (F1), the integral value of the aliphatic dicarboxylic acid (a1) and the integral value of the second dicarboxylic acid (a2) (i.e., a dicarboxylic acid different from the aliphatic dicarboxylic acid (a1)) are the integral values ​​of the signals within the following range. Furthermore, when using two or more second dicarboxylic acids (a2), the integral value is the sum of their integral values.

[0202] • When the aliphatic dicarboxylic acid (a1) is 3-methylpentanediic acid (also known as 3-methylglutaric acid): the integral value of the 3H signal of the methyl group at δ 1.1~1.2 ppm.

[0203] • When the aliphatic dicarboxylic acid (a1) is methylsuccinic acid: the integral value of the 3H signal of the methyl group at δ 1.4–1.5 ppm.

[0204] • When the second dicarboxylic acid (a2) is adipic acid: the integral value of the 4H signal of the methylene group at δ 2.5–2.6 ppm.

[0205] • When the second dicarboxylic acid (a2) is terephthalic acid: the integral value of the 4H signal of the aromatic ring at δ 8.0–8.5 ppm.

[0206] • When the second dicarboxylic acid (a2) is succinic acid: the integral value of the 4H signal of the methylene group at δ 2.8–3.0 ppm

[0207] It should be noted that the content of the second dicarboxylic acid (a2) is calculated as follows, except that the second dicarboxylic acid (a2) (or the sum of their integral values ​​when using two or more second dicarboxylic acids (a2)) is used as the molecule.

[0208] In addition, the content of aliphatic diol (b1) is calculated according to the following formula (F2), in the same manner as the steps above.

[0209] The ratio (molar %) of aliphatic diols (b1)

[0210] =(Integral value of aliphatic diol (b1) / number of protons) × 100 / [(Integral value of aliphatic diol (b1) / number of protons) + (Integral value of the second diol (b2) / number of protons)] … Equation (F2)

[0211] In the above formula (F2), the integral value of the aliphatic diol (b1) and the integral value of the second diol (b2) (i.e., a diol different from the aliphatic diol (b1)) are the integral values ​​of the signals within the following range. Furthermore, when using two or more second diols (b2), the integral value is the sum of their integral values.

[0212] • When the aliphatic diol (b1) is 3-methyl-1,5-pentanediol: the integral value of the 3H signal of the methyl group at δ 1.0~1.2 ppm.

[0213] • When the second diol (b2) is butanediol: the integral value of the 4H signal of the methylene group at δ 4.5–4.7 ppm.

[0214] [Determination of number-average molecular weight (Mn) and weight-average molecular weight (Mw)]

[0215] Number-average molecular weight (Mn) and weight-average molecular weight (Mw) were determined using a size-exclusion high-performance liquid chromatography (HPLC) apparatus manufactured by Shimadzu Corporation. The determination conditions are as follows.

[0216] Columns: Two HFIP series columns “GMHHR-H(S)” manufactured by Tosoh Corporation, connected in series.

[0217] Standard sample: Polymethyl methacrylate (PMMA) resin

[0218] Solvent and mobile phase: 1,1,1,3,3,3-hexafluoroisopropanol (HFIP)

[0219] Flow rate: 0.35 mL / min

[0220] Temperature: 40℃

[0221] Sample solution concentration: 0.1% by weight (filtered using a 0.45 μm aperture filter).

[0222] Injection volume: 10 μL

[0223] Detector: LC-20AD (RI detector)

[0224] [Determination of intrinsic viscosity (IV) of solutions]

[0225] (Determination Method)

[0226] Dissolve 0.200 g of polyester resin (hereinafter referred to as "sample solution") in 20 mL of a phenol / 1,1,2,2-tetrachloroethane = 50 / 50 mass % solution (hereinafter sometimes simply referred to as "solvent"). Weigh 10 mL of solvent into a dilution-type Ubbelohde viscometer IC manufactured by Asahi Seisakusho Co., Ltd. using a pipette, and immerse the viscometer in a 30°C water bath. Measure the time (t0) for the solvent level to fall naturally from the upper mark to the lower mark. After measuring t0, dry the apparatus, and similarly weigh 10 mL of sample solution into a viscosity tube for measurement (t1). After measuring t1, add 10 mL of solvent to the viscometer and perform the same measurement (t2). After measuring t2, add another 10 mL of solvent to the viscometer and perform the same measurement (t3).

[0227] (Calculation method)

[0228] η is calculated according to the following formulas (F3) and (F4). spx (x=1, 2, 3).

[0229] η rx =tx / t0 …Equation (F3)

[0230] η spx =η rx -1 …Formula (F4)

[0231] For x=1, 2, 3, the horizontal axis is set to the sample solution concentration Co. x (g / dL), with the vertical axis set to η at each concentration. spx Plot the graph and use the intercept with the vertical axis as the intrinsic viscosity (IV) of the solution.

[0232] [Production of the pressed film]

[0233] The polyester resins or resin compositions of the examples and comparative examples were pressed at 180–190°C for 60 seconds to produce pressed films with a thickness of 120–150 μm. It should be noted that the thickness of each pressed film was measured using a micrometer.

[0234] [Evaluation of compostability]

[0235] Except for the use of test cups (external dimensions: Φ96×110mm, material: PP), the tests were conducted in the same manner as JIS K6954:2008 to evaluate the compostability of the polyester resins and resin compositions of the examples and comparative examples. Simulated compost (synthetic solid waste) was prepared with the composition shown in Table 1 below.

[0236]

[0237] Cut 15mm×15mm pieces from the pressed film to make test pieces.

[0238] Weigh 90g of simulated compost into a cup. Place a test piece in the center of the simulated compost both horizontally and vertically. Cover the cup. Place the cup in a 58℃ constant temperature bath. Periodically remove the compost, add water to the initial weight, and stir the compost until the experiment ends after 30 days. At the end of the experiment, sieve the compost through a 4.75mm and 2.0mm sieve. Collect the test piece from the residue, dry it, and measure its weight. Set the initial weight as 100 and calculate the weight retention rate. Classify the weight retention rate as follows: below 30% as "A", 30-85% as "B", and above 85% as "C".

[0239] It should be noted that, for reference, the appearance photographs of the polyester resins of Example 2 and Comparative Example 1 after their compostability evaluation are shown in the figures. Figure 1 (Example 2) and Figure 2 (Comparative Example 1)

[0240] [Evaluation of hydrolysis resistance]

[0241] The membrane prepared using the method described in the "Preparation of Pressed Membrane" section was cut into strips of 20 mm × 60 mm, immersed in hot water at 80°C, and left to stand. After 7 days, the membrane was removed, a portion was cut off, and dried in a dryer at 40°C and 1.3 Pa for 20 hours. The weight-average molecular weight was then determined according to the method described above. The molecular weight retention rate was calculated when the weight-average molecular weight used for the experiment was set to 100.

[0242] Then, cases with a molecular weight retention rate of 71% or higher are designated as "A", cases with a molecular weight retention rate of 61-70% are designated as "B", and cases with a molecular weight retention rate of less than 60% are designated as "C".

[0243] It should be noted that, for reference, photographs of the polyester resins of Example 5 and Comparative Example 1 after 14 days of hydrolysis resistance evaluation are shown in the figures. Figure 3 (Example 5) and Figure 4 (Comparative Example 1)

[0244] [Comprehensive evaluation of biodegradability and hydrolysis resistance]

[0245] When the evaluations of biodegradability and hydrolysis resistance are "A" and "A", "A" and "B", and "B" and "A", the balance between the two is considered good. When any evaluation is "C" or both are "B", the balance between these properties is considered poor.

[0246] [Evaluation of Mechanical Properties]

[0247] The membranes produced using the method described in the "Preparation of Pressed Membrane" section were cut into dumbbell shapes with a width of 10 mm. After being conditioned for one week at 23°C and 50% RH, the elongation at break was measured using an Autograph (Shimadzu Corporation AG-5000B) (force sensor 1 kN, tensile speed 500 mm / min (Examples 4, 5, 6, Comparative Example 3), tensile speed 5 mm / min (Examples 1-3, 7, Comparative Examples 1, 2), clamp distance 70 mm). The elongation at break values ​​listed in Table 3 below are the average of three measurements.

[0248] [Example 1]

[0249] 5.6 parts by mass of 3-methylpentane dianhydride (a1) as an aliphatic dicarboxylic acid, 46.7 parts by mass of succinic acid (a2)-1 (a2) as a second dicarboxylic acid, 47.6 parts by mass of 1,4-butanediol (B) as an aliphatic diol, and 0.06 parts by mass of tetrabutoxytitanium (a1) as a catalyst were added to a reactor. Then, the reactor was heated to 190°C under atmospheric pressure and a nitrogen atmosphere, and the esterification reaction was carried out while the generated water was distilled off the system.

[0250] When the distillation of generated water decreases, the pressure is reduced to 0.15 mmHg using a vacuum pump, and the reaction is carried out at 200°C. Stirring is stopped when the torque reaches 90 mA under stirring conditions of 230°C and 180 rpm. Then, the molten resin is removed with a metal spatula and allowed to cool to obtain polyester resin "PES-1".

[0251] [Example 2]

[0252] The 3-methylpentane dianhydride was changed to 11.2 parts by mass, the succinic acid was changed to 41.3 parts by mass, and the 1,4-butanediol was changed to 47.4 parts by mass. Otherwise, the reaction was carried out in the same manner as in Example 1 to obtain the polyester resin "PES-2".

[0253] [Example 3]

[0254] The 3-methylpentane dianhydride was changed to 2.8 parts by mass, the succinic acid was changed to 49.4 parts by mass, and the 1,4-butanediol was changed to 47.7 parts by mass. Otherwise, the reaction was carried out in the same manner as in Example 1 to obtain the polyester resin "PES-3".

[0255] [Example 4]

[0256] Using 29.2 parts by mass of 3-methylpentane dianhydride as an aliphatic dicarboxylic acid (a1), and 29.5 parts by mass of dimethyl terephthalate as the second dicarboxylic acid (a2)-1, and changing 1,4-butanediol to 41.3 parts by mass, the reaction was carried out in the same manner as in Example 1 to obtain polyester resin "PES-4".

[0257] [Example 5]

[0258] Using 34.9 parts by mass of 3-methylpentane dianhydride as an aliphatic dicarboxylic acid (a1), using 22.7 parts by mass of dimethyl terephthalate as the second dicarboxylic acid (a2)-1, and changing 1,4-butanediol to 42.4 parts by mass, the reaction was carried out in the same manner as in Example 1 to obtain polyester resin "PES-5".

[0259] [Example 6]

[0260] Using 11.5 parts by weight of methylsuccinic acid as an aliphatic dicarboxylic acid (a1), 41.2 parts by weight of succinic acid as the second dicarboxylic acid (a2)-1, and changing 1,4-butanediol to 47.2 parts by weight, the reaction was carried out in the same manner as in Example 1 to obtain polyester resin "PES-6".

[0261] [Example 7]

[0262] 100 parts by weight of the above-mentioned PES-2 and 0.2 parts by weight of Carbodilite HMV-5CA-LC (trade name) manufactured by Nisshinbo Chemical Co., Ltd. were filled with resin for 3 minutes using Labo Plastomill (registered trademark) manufactured by Toyo Seiki Co., Ltd., and then mixed at 190°C for 5 minutes. The melt was then cooled and solidified to obtain a resin composition.

[0263] [Example 8]

[0264] A resin composition was obtained by mixing 100 parts by weight of the above-mentioned PES-4 and 0.2 parts by weight of Carbodilite HMV-5CA-LC (trade name) manufactured by Nisshinbo Chemical Co., Ltd. in the same manner as in Example 7 and then curing it.

[0265] [Comparative Example 1]

[0266] Instead of using aliphatic dicarboxylic acids (a1), 52.1 parts by mass of succinic acid were used as the second dicarboxylic acid (a2)-1 and 47.8 parts by mass of 1,4-butanediol. Otherwise, the reaction was carried out in the same manner as in Example 1 to obtain the polyester resin "PES-7".

[0267] [Comparative Example 2]

[0268] Instead of using aliphatic dicarboxylic acids (a1), 40.7 parts by mass of succinic acid as the second dicarboxylic acid (a2)-1, 12.6 parts by mass of adipic acid as the second dicarboxylic acid (a2)-2, and 46.7 parts by mass of 1,4-butanediol were used. The reaction was carried out in the same manner as in Example 1 to obtain the polyester resin "PES-8".

[0269] [Comparative Example 3]

[0270] Instead of using aliphatic dicarboxylic acids (a1), 34.8 parts by mass of terephthalic acid as the second dicarboxylic acid (a2)-1, 26.2 parts by mass of adipic acid as the second dicarboxylic acid (a2)-2, and 38.9 parts by mass of 1,4-butanediol were used. The reaction was carried out in the same manner as in Example 1 to obtain polyester resin "PES-9".

[0271] [Comparative Example 4]

[0272] A resin composition was obtained by mixing 100 parts by weight of PES-7 and 1 part by weight of Carbodilite HMV-5CA-LC (trade name) manufactured by Nisshinbo Chemical Co., Ltd. in the same manner as in Example 7 and then curing it.

[0273] [Comparative Example 5]

[0274] A resin composition was obtained by mixing 100 parts by weight of PES-9 and 1 part by weight of Carbodilite HMV-5CA-LC (trade name) manufactured by Nisshinbo Chemical Co., Ltd. in the same manner as in Example 7 and then curing it.

[0275] [Example A1]

[0276] Instead of using aliphatic dicarboxylic acids (a1), 33.9 parts by mass of dimethyl terephthalate were used as the second dicarboxylic acid (a2)-1, 25.5 parts by mass of adipic acid were used as the second dicarboxylic acid (a2)-2, 12.4 parts by mass of 3-methyl-1,5-pentanediol was used as the aliphatic diol (b1), and 28.2 parts by mass of 1,4-butanediol was used as the second diol (b2). Otherwise, the reaction was carried out in the same manner as in Example 1 to obtain the polyester resin "PES-10".

[0277] [Example A2]

[0278] Instead of using aliphatic dicarboxylic acids (a1), 33.2 parts by mass of dimethyl terephthalate were used as the second dicarboxylic acid (a2)-1, 25.0 parts by mass of adipic acid were used as the second dicarboxylic acid (a2)-2, 20.2 parts by mass of 3-methyl-1,5-pentanediol were used as the aliphatic diol (b1), and 21.6 parts by mass of 1,4-butanediol were used as the second diol (b2). Otherwise, the reaction was carried out in the same manner as in Example 1 to obtain the polyester resin "PES-11".

[0279] [Example A3]

[0280] The polyester resin “PES-12” was obtained by reacting with 11.2 parts by mass of 3-methylpentane dianhydride as aliphatic dicarboxylic acid (a1)-1, 0.06 parts by mass of methylsuccinic acid as aliphatic dicarboxylic acid (a1)-2, 41.3 parts by mass of succinic acid as second dicarboxylic acid (a2), and 47.4 parts by mass of 1,4-butanediol as second diol (b2), except that the reaction was carried out in the same manner as in Example 1.

[0281] [Example A4]

[0282] A resin composition was obtained by mixing 100 parts by weight of the above-mentioned PES-10 and 0.6 parts by weight of Carbodilite HMV-5CA-LC (trade name) manufactured by Nisshinbo Chemical Co., Ltd. in the same manner as in Example 7 and then curing it.

[0283]

[0284] As shown in Tables 2 and 3, the polyester resins of Examples 1-6 and Examples A1-A3, as well as the resin compositions of Examples 7-8 and Example A4, exhibit good hydrolysis resistance and compostability.

[0285] On the other hand, as shown in Comparative Example 1, PES-7, as polybutylene succinate, does not have sufficient compostability.

[0286] In addition, as shown in Comparative Example 2, PES-8, which contains polybutylene succinate with a structure derived from adipic acid, has good compostability but poor hydrolysis resistance.

[0287] In addition, as shown in Comparative Example 3, PES-9, as polybutylene adipate terephthalate, exhibits poor compostability and hydrolysis resistance.

[0288] Furthermore, as in Comparative Examples 4 and 5, the compostability of resin compositions using a combination of PES-7 or PES-9 and Carbodilite was insufficient.

[0289] Industrial availability

[0290] According to the present invention, it is possible to provide biodegradable polyester resins, biodegradable polyester resin compositions, and molded articles thereof that have excellent biodegradability and excellent hydrolysis resistance.

[0291] The biodegradable polyester resin, biodegradable polyester resin composition, and their molded forms are useful in applications such as agricultural multilayer films, compost bags, food packaging films, and disposable tableware.

Claims

1. A biodegradable polyester resin comprising structural units derived from a dicarboxylic acid component (A) and structural units derived from an aliphatic diol component (B), wherein the biodegradable polyester resin satisfies at least one of the following conditions (α) and (β). • Condition (α): The dicarboxylic acid component (A) contains a first dicarboxylic acid component (A1) consisting of at least one compound selected from the group consisting of aliphatic dicarboxylic acids (a1) represented by the following formula (I) and their derivatives; • Condition (β): The aliphatic diol component (B) contains a first aliphatic diol component (B1) consisting of at least one compound selected from the aliphatic diols (b1) shown in formula (II) below. In equations (I) and (II), R 1 R 2 R 5 R 6 Each independently represents a divalent hydrocarbon group with 1 to 3 carbon atoms, R 3 R 7 Each independently represents a monovalent hydrocarbon group having 1 to 3 carbon atoms, R 4 R 8 Each of the following groups independently represents a monovalent hydrocarbon group with 1 to 3 hydrogen or carbon atoms, and m, n, x, and y independently represent 0 or 1.

2. The biodegradable polyester resin according to claim 1, wherein, The dicarboxylic acid component (A) comprises the first dicarboxylic acid component (A1) and the second dicarboxylic acid component (A2), wherein the second dicarboxylic acid component (A2) is composed of a compound selected from the group consisting of a second dicarboxylic acid (a2) different from the aliphatic dicarboxylic acid (a1) and its derivatives. The biodegradable polyester resin satisfies either (i) or (ii) the following condition. • Condition (i): The number of carbon atoms in the dicarboxylic acid contained in the second dicarboxylic acid component (A2) and the number of carbon atoms in the aliphatic diol component (B) are both 4 or less; • Condition (ii): The second dicarboxylic acid component (A2) contains an aromatic dicarboxylic acid.

3. The biodegradable polyester resin according to claim 2, wherein, The second dicarboxylic acid component (A2) contains aromatic dicarboxylic acids.

4. The biodegradable polyester resin according to any one of claims 1 to 3, wherein, The content of the aliphatic dicarboxylic acid (a1) in the dicarboxylic acid component (A) is 2 to 60 moles.

5. The biodegradable polyester resin according to any one of claims 1 to 4, wherein, R in equation (I) 1 R 2 All are methylene.

6. The biodegradable polyester resin according to any one of claims 1 to 5, wherein, R in equation (I) 3 For methyl, R 4 It is a hydrogen atom.

7. The biodegradable polyester resin according to any one of claims 1 to 6, wherein, The content of the first aliphatic diol component (B1) in the aliphatic diol component (B) is 2 to 50 mol.

8. The biodegradable polyester resin according to any one of claims 1 to 7, wherein, R in equation (II) 5 and R 6 It is a methylene group.

9. The biodegradable polyester resin according to any one of claims 1 to 8, wherein, R in equation (II) 7 For methyl, R 8 It is a hydrogen atom.

10. The biodegradable polyester resin according to any one of claims 1 to 9, wherein, The dicarboxylic acid component (A) does not contain aliphatic dicarboxylic acids (a2X) with branched chains and hydroxyl groups, or the content of the aliphatic dicarboxylic acid (a2X) in the dicarboxylic acid component (A) is greater than 0 mol% and less than 3 mol%.

11. The biodegradable polyester resin according to any one of claims 1 to 10, wherein, The dicarboxylic acid component (A) contains the first dicarboxylic acid component (A1), the second dicarboxylic acid component (A2), and the third dicarboxylic acid component (A3). The second dicarboxylic acid component (A2) is composed of a compound selected from the group consisting of a second dicarboxylic acid (a2) different from the aliphatic dicarboxylic acid (a1) and its derivatives. The third dicarboxylic acid component (A3) is composed of a compound selected from the group consisting of a third dicarboxylic acid (a3) ​​different from the aliphatic dicarboxylic acid (a1) and the second dicarboxylic acid (a2) and its derivatives.

12. The biodegradable polyester resin according to claim 11, wherein, The third dicarboxylic acid (a3) ​​is methylsuccinic acid.

13. A biodegradable polyester resin composition comprising the biodegradable polyester resin according to any one of claims 1 to 12 and a hydrolysis resistant agent (C).

14. The biodegradable polyester resin composition according to claim 13, wherein, The hydrolysis resistant agent (C) is a carbodiimide compound.

15. The biodegradable polyester resin composition according to claim 13 or 14, wherein, The content of the hydrolysis resistant agent (C) is 0.15 to 2 parts by weight relative to 100 parts by weight of the biodegradable polyester resin.

16. A molded article comprising the biodegradable polyester resin of any one of claims 1 to 12 or the biodegradable polyester resin composition of any one of claims 13 to 15.

17. A membrane comprising the biodegradable polyester resin of any one of claims 1 to 12 or the biodegradable polyester resin composition of any one of claims 13 to 15.

18. A sheet comprising the biodegradable polyester resin of any one of claims 1 to 12 or the biodegradable polyester resin composition of any one of claims 13 to 15.

19. A food utensil comprising the biodegradable polyester resin of any one of claims 1 to 12 or the biodegradable polyester resin composition of any one of claims 13 to 15.

20. A plastic modifier comprising the biodegradable polyester resin of any one of claims 1 to 12 or the biodegradable polyester resin composition of any one of claims 13 to 15.

21. A coating agent comprising the biodegradable polyester resin of any one of claims 1 to 12 or the biodegradable polyester resin composition of any one of claims 13 to 15.

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