Biodegradable resin composition and molded article

Abstract

Provided is a biodegradable resin composition that has a high rate of biodegradation and a high degree of biodegradation. [Solution] The biodegradable resin composition contains a polyester resin and one or more compounds selected from nitrogen compounds represented by formula (I) and salts thereof, wherein the polyester resin is a resin having dicarboxylic acid units and diol units, and has three or more types of structural units, including at least one of succinic acid units and sebacic acid units, the nitrogen compound is a straight-chain aliphatic hydrocarbon (excluding "amino acids") containing two or more amino groups and two or more primary amino groups in the molecule, the content of the compound is 0.1% by weight or more and 70% by weight or less, the nitrogen atom concentration in the compound is 6% by weight or more, and the molecular weight of the compound is less than 10,000. JPEG2023055686000009.jpg1978 (In the formula, R, R', and R'' each independently represent a hydrogen atom or a monovalent organic group which may have substituents that do not form a ring structure with each other.)

Description

[Technical Field]

[0001] The present invention relates to a biodegradable resin composition and a molded article containing the biodegradable resin composition. [Background technology]

[0002] In modern society, plastics are used in a wide range of everyday applications, such as packaging materials, home appliance materials, and building materials, due to their light weight, electrical insulation, moldability, and durability. Plastics used for these applications include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. However, molded products made from these plastics are difficult to decompose in the natural environment and tend to remain in the ground even when buried after use. Furthermore, incineration can produce harmful gases that can damage incinerators. Therefore, in recent years, there has been a worldwide demand for products that can be composted in ordinary households (home-compostable products) in order to prevent environmental pollution.

[0003] As a means of solving the above problems, research has been conducted into biodegradable materials that can be decomposed into carbon dioxide and water by microorganisms in compost. Representative examples of biodegradable materials include biodegradable resins such as polylactic acid (hereinafter sometimes abbreviated as "PLA") (Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Polymer Degradation and Stability 98 (2013) 1089-1096 Summary of the Invention [Problem to be solved by the invention]

[0005] Furthermore, while plastic waste in the ocean has become a problem in recent years, no research has been conducted into resins that biodegrade in the ocean. In particular, there are few decomposing bacteria in seawater, so even resins that can be decomposed in compost are more difficult to decompose. Therefore, an object of the present invention is to provide a biodegradable resin composition that has a fast biodegradation rate and a high degree of biodegradation, and in particular, to provide a biodegradable resin composition that has a fast biodegradation rate and a high degree of biodegradation in the ocean. [Means for solving the problem]

[0006] The present inventors have conducted extensive research in light of the above-mentioned circumstances. Specifically, they focused on compounds containing amino groups and believed that compounds with amino groups contribute to promoting degradation. That is, they focused on the biofilm formation effect, which is thought to be necessary for degradation in seawater, and when various resins were used in combination with polyamines, they found that specific polyamines significantly promoted the biodegradation of specific polyester resins in seawater. Further research led to the discovery that specific nitrogen compounds have a significant effect of promoting the biodegradation of specific polyester resins, thereby solving the above-mentioned problems, and thus completed the present invention. That is, the gist of the present invention is as follows.

[0007] [1] A biodegradable resin composition containing a polyester resin and one or more compounds selected from nitrogen compounds represented by the following general formula (I) and salts thereof (excluding (RS)-1-methyl-2-nitro-3-[(3-tetrahydrofuryl)methyl]guanidine, compounds represented by the general formula NH2-CHR-COOH (wherein R represents hydrogen or a monovalent aliphatic hydrocarbon group), and phenylalanine), wherein the polyester resin is a resin having dicarboxylic acid units and diol units, has three or more types of structural units, and has at least one unit selected from succinic acid units and sebacic acid units, the nitrogen compound is a straight-chain aliphatic hydrocarbon (excluding "amino acids") containing two or more amino groups and two or more primary amino groups in the molecule, the content of the compound is 0.1% by weight or more and 70% by weight or less, the nitrogen atom concentration in the compound is 6% by weight or more, and the molecular weight of the compound is less than 10,000. [ka] (In the formula, R, R', and R'' each independently represent a hydrogen atom or a monovalent organic group which may have substituents that do not form a ring structure with each other.) [2] A biodegradable resin composition containing a polyester resin and one or more compounds selected from nitrogen compounds represented by the following general formula (II) and salts thereof (excluding (RS)-1-methyl-2-nitro-3-[(3-tetrahydrofuryl)methyl]guanidine), wherein the polyester resin is a resin having dicarboxylic acid units and diol units, and has three or more types of structural units, including at least one of succinic acid units and sebacic acid units; the nitrogen compound is a straight-chain aliphatic hydrocarbon (excluding "amino acids") containing two or more amino groups and two or more primary amino groups in the molecule; the content of the compound is 0.1% by weight or more and 70% by weight or less; the nitrogen atom concentration in the compound is 6% by weight or more; and the molecular weight of the compound is 90 or more and less than 10,000. [ka] (In the formula, R, R', and R'' each independently represent a hydrogen atom or a monovalent aliphatic organic group, and the aliphatic organic group may have substituents that do not mutually form a ring structure.) [3] The biodegradable resin composition according to [1] or [2] above, wherein the concentration of nitrogen atoms derived from the compound contained in the resin composition is 50 ppm by weight or more. [4] The biodegradable resin composition according to [1] or [3] above, wherein the monovalent organic group which may have a substituent is a monovalent chain aliphatic organic group having 1 to 20 carbon atoms which may have a substituent, the main chain of the organic group may contain an element of Groups 15 to 17, and the organic group may contain one or more elements selected from the group consisting of a nitrogen atom, a sulfur atom, and a phosphorus atom. [5] The biodegradable resin composition according to [2] or [3] above, wherein the monovalent aliphatic organic group which may have a substituent is a monovalent chain aliphatic organic group having 1 to 20 carbon atoms which may have a substituent, the main chain of the aliphatic organic group may contain an element of Groups 15 to 17, and the aliphatic organic group may contain one or more elements selected from the group consisting of a nitrogen atom, a sulfur atom, and a phosphorus atom. [6] The biodegradable resin composition according to any one of the above [1] to [5], wherein the compound is at least one selected from the group consisting of spermine, tetramethylenediamine, spermidine, and hydrochlorides thereof. [7] The biodegradable resin composition according to any one of the above [1] to [6], wherein the acid value of the polyester resin is 19 eq / t or more and 250 eq / t or less. [8] The biodegradable resin composition according to any one of the above [1] to [7], wherein the polyester resin is an aliphatic polyester resin or an aliphatic-aromatic polyester resin. [9] The biodegradable resin composition according to any one of the above [1] to [8], wherein the polyester resin has, as a diol unit, one or more diols selected from the group consisting of 1,4-butanediol, 1,3-propanediol, and ethylene glycol.

[10] The biodegradable resin composition according to any one of the above [1] to [9], wherein the polyester resin has, as the dicarboxylic acid unit, a dicarboxylic acid having 2 to 24 carbon atoms.

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

[10] , wherein the polyester resin is at least one selected from the group consisting of PBSA (polybutylene succinate adipate), PBSSe (polybutylene succinate sebacate), PBS (polybutylene succinate), and PBSeT (polybutylene sebacate terephthalate).

[12] A molded article comprising the biodegradable resin composition according to any one of [1] to

[11] above. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a biodegradable resin composition that has a high rate of biodegradation and a high degree of biodegradation, and this will make a significant contribution to solving environmental problems, particularly marine pollution. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described in detail. The present invention is not limited to the following description, and can be implemented by any modifications within the scope of the gist of the present invention. In this specification, when a numerical value or a physical property value is enclosed by "~", the value before and after the "~" is used to include the values ​​before and after the "~"

[0010] The present invention will be described in detail below. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents, and can be implemented in various modifications within the scope of its gist.

[0011] One embodiment of the present invention is a biodegradable resin composition containing a polyester resin and a specific nitrogen compound (hereinafter, sometimes referred to as the "biodegradable resin composition according to this embodiment" or the "resin composition of the present invention"). In this specification, "biodegradable" means a property in which a resin is decomposed by the action of microorganisms through hydrolysis or the like into low molecular weight compounds such as oligomers and monomers, which are then further decomposed into water, carbon dioxide, etc. The resin composition of the present invention is usually biodegraded in at least one of the following environments: seawater, freshwater, brackish water, soil, or compost. In particular, the amount and variety of microorganisms in seawater are small, making it difficult for resins to biodegrade. However, the resin composition of the present invention can be effective in such an environment where biodegradation is difficult. In other words, it is preferable that the resin composition of the present invention is highly biodegradable in seawater (marine biodegradable resin composition). The components, properties, production method, and uses of the biodegradable resin composition according to this embodiment will be described below.

[0012] [Nitrogen compounds and their salts] First Embodiment The biodegradable resin composition according to the first embodiment of the present invention contains one or more compounds selected from nitrogen compounds represented by the following general formula (I) (hereinafter, sometimes referred to as "nitrogen compound (I)") and salts thereof (hereinafter, sometimes referred to as "compounds such as nitrogen compound (I)").

[0013] [ka]

[0014] In the formula, R, R', and R'' each independently represent a hydrogen atom or a monovalent organic group which may have substituents that do not mutually form a ring structure. However, from compounds such as nitrogen compound (I), (RS)-1-methyl-2-nitro-3-[(3-tetrahydrofuryl)methyl]guanidine, 1 -COOH(where R 1 represents hydrogen or a monovalent aliphatic hydrocarbon group) and phenylalanine are excluded. At least one of the monovalent organic groups R, R', and R'' which may have a substituent is preferably an aliphatic organic group which may have an element of Groups 15 to 17 in the main chain or side chain, and more preferably contains at least one of a nitrogen atom, a phosphorus atom, a sulfur atom, a fluorine atom, and a chlorine atom in the main chain or side chain. Furthermore, this organic group which may have a substituent is more preferably a monovalent chain aliphatic organic group having 1 to 20 carbon atoms. At least one of R, R', and R'' is preferably a hydrogen atom, and two are more preferably hydrogen atoms.

[0015] Examples of elements of Groups 15 to 17 that the organic group may have in its main chain include nitrogen, oxygen, sulfur, phosphorus, selenium, fluorine, chlorine, and bromine. Of these, nitrogen, sulfur, and phosphorus are preferred, nitrogen and phosphorus are more preferred, and nitrogen is most preferred. The organic group may also have one or more atoms selected from the group consisting of elements of Groups 15 to 17 in its side chain. The organic group may be an aliphatic organic group or an aromatic organic group. The aliphatic organic group may be linear or cyclic. It may also have a carbon-carbon unsaturated bond. Of these, the organic group is preferably an aliphatic organic group, and among aliphatic organic groups, linear aliphatic organic groups are more preferred. It is also preferred that at least one of R, R', and R'' is an aliphatic organic group which may have a substituent.

[0016] The phrase "may contain one or more atoms selected from the group consisting of elements of Groups 15 to 17" means that the organic group may contain, as a substituent, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an astatine atom, a primary amino group, a hydroxyl group, a carboxyl group, a thiol group, an acetyl group, a carboxymethyl group, or the like. It also means that the organic group may contain, in its carbon skeleton, a linking group containing a nitrogen atom or a sulfur atom, such as a secondary amino group, a tertiary amino group, an ether bond, a carbonyl bond, or a thioether bond. Among these, preferred substituents include a primary amino group (-NH), a hydroxyl group, or a carboxyl group, or a secondary amino group (-NH-) or an ether bond, with primary amino groups or secondary amino groups being more preferred. The phrase "containing a secondary amino group in the carbon skeleton of the organic group" does not refer to a polymer containing a repeating unit having an amino group in the polymer main chain. The number of carbon atoms in the organic group is not particularly limited, and may be appropriately selected within the molecular weight range of the nitrogen compound (I) or a salt thereof, as described below. However, from the viewpoints of biodegradability-promoting effect, availability, workability, etc., the number of carbon atoms in the main chain of at least one of the organic groups is usually 1 or more, preferably 3 or more, more preferably 4 or more, and particularly preferably 5 or more. It is also usually 40 or less, preferably 20 or less, more preferably 16 or less, even more preferably 11 or less, particularly preferably 8 or less, and most preferably 6 or less. The number of carbon atoms, including any substituents, is usually 3 or more, preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more. It is also usually 45 or less, preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, and particularly preferably 6 or less. From the viewpoint of promoting the decomposition of biodegradable resins in seawater, it is preferable that compounds such as the nitrogen compound (I) are easily eluted in seawater. Here, WO2009 / 113288 discloses a method for preparing a polyester resin having a slow crystallization rate, which is prepared by using a specific crystal nucleating agent (general formula: NH2-CHR 1 -COOH(where R 1A technique using a compound represented by the formula (I) (wherein R represents hydrogen or a monovalent aliphatic hydrocarbon group) and phenylalanine) has been disclosed. However, since the nucleating agent is considered to be insoluble, the nucleating agent disclosed in WO2009 / 113288 is excluded from the compounds such as nitrogen compound (I) according to the present invention.

[0017] Second Embodiment The biodegradable resin composition according to the second embodiment of the present invention contains one or more compounds (compounds such as nitrogen compound (II)) selected from nitrogen compounds represented by the following general formula (II) (nitrogen compound (II)) and salts thereof (excluding (RS)-1-methyl-2-nitro-3-[(3-tetrahydrofuryl)methyl]guanidine). [ka] (In the formula, R, R', and R'' each independently represent a hydrogen atom or a monovalent aliphatic organic group, and the aliphatic organic group may have substituents that do not mutually form a ring structure.) From the viewpoint of promoting the decomposition of the biodegradable resin, it is preferable that the nitrogen compounds (I) etc. and (II) etc. are easily eluted in seawater. Therefore, it is preferable that the NH2 dissociation constant (pKa) of the nitrogen compounds (I) and (II) is small, since the nitrogen compounds (I) and (II) are easily eluted as ions in seawater.

[0018] Specifically, the NH2 dissociation constant (pKa) is preferably 9.75 or less, more preferably 9.60 or less, even more preferably 9.30 or less, particularly preferably 9.15 or less, and most preferably 9.00 or less. On the other hand, from the viewpoint of ease of handling, it is preferably 6.00 or more, more preferably 8.00 or more, particularly preferably 8.50 or more, even more preferably 8.80 or more, and most preferably 8.90 or more. The NH2 dissociation constant (pKa) is described in Molecular Cloning Vol. 3 Appendix 7. From the viewpoint of ease of elution in seawater, the aliphatic organic groups of the nitrogen compounds (I) and (II) preferably have a substituent other than a hydrocarbon group, and the substituent is preferably a hydrophilic group. The hydrophilic group is not particularly limited, but preferably includes an amino group, a hydroxy group, a sulfo group, a thiol group, an amide group, a carboxy group, an aldehyde group, or the like, more preferably includes an amino group, a hydroxy group, a sulfo group, a thiol group, or an amide group, even more preferably includes an amino group, a hydroxy group, a sulfo group, or a thiol group, particularly preferably includes an amino group or a hydroxy group, and most preferably includes an amino group. The hydrophilic groups are preferably one or more, more preferably two or more, even more preferably three or more, and particularly preferably four or more. The number of hydrophilic groups is typically nine or less, preferably seven or less, and even more preferably five or less. The partition coefficient logD of the nitrogen compounds (I) and (II), which indicates hydrophobicity, is preferably -3.45 or less. The partition coefficient logD is more preferably -3.60 or less, even more preferably -4.00 or less, particularly preferably -4.40 or less, even more preferably -5.00 or less, and most preferably -5.10 or less. The partition coefficient logD is preferably -10.00 or more, more preferably -8.00 or more, even more preferably -7.00 or more, particularly preferably -6.00 or more, and most preferably -5.20 or more. The partition coefficient logD can be calculated using the CAS SciFinder n(https: / / www.jaici.or.jp / sshifwinder-n / ) is calculated from the estimated value at pH 7. Furthermore, the hydrophobicity index (an index representing the water solubility) of the nitrogen compounds (I) and (II) is preferably high from the viewpoint of promoting the degradation of biodegradable resins. Specifically, it is preferably −10.0 or higher, more preferably −5.0 or higher, even more preferably −4.5 or higher, and particularly preferably −4.0 or higher. On the other hand, it is preferably 0.0 or lower, more preferably −0.5 or lower, even more preferably −2.0 or lower, particularly preferably −3.0 or lower, even more preferably −3.5 or lower, and most preferably −4.0 or lower. The hydrophobicity index is introduced in Kyte and Doolittle, J. Mol. Biol., 157, 105-132 (1982), and is calculated from hydrophilic and hydrophobic properties. The preferred ranges of the monovalent aliphatic organic groups R, R', and R'' are the same as the preferred ranges of the monovalent organic groups optionally having a substituent R, R', and R'' in the first embodiment.

[0019] Specific examples of the nitrogen compounds (I) and (II) include monoalkylamines such as propylamine, butylamine, pentylamine, hexylamine, and isobutylamine; dialkylamines such as dimethylamine and diethylamine; trialkylamines such as N-butyldimethylamine; alkylenediamines such as trimethylenediamine, tetramethylenediamine (putrescine), pentamethylenediamine (cadaverine), hexamethylenediamine, heptamethylenediamine, octamethylenediamine, and decamethylenediamine; bis(3-aminopropyl)amine, N-(3-aminopropyl)-1,3-propanediamine (norspediamin), and the like. alkylenediamines having an NH group in the alkylene skeleton, such as N,N'-bis(3-aminopropyl)-1,4-butanediamine (spermine), N-(3-aminopropyl)tetramethylenediamine (spermidine), N,N'-bis(3-aminopropyl)-1,4-butanediamine (spermine), 3,3'-diamino-N-methyldipropylamine, and N-benzyl-1,3-propanediamine; amino sugars such as glucosamine and neuraminic acid; amino sugar derivatives such as N-acetylglucosamine, muramic acid, N-acetylmuramic acid, N-acetylneuraminic acid, and N-acetylgalactosamine; imide compounds; and amide compounds such as N-butylpropionamide and N-ethylacetamide. Among these, preferred nitrogen compounds (I) and (II) include monoalkylamines such as hexylamine and isobutylamine; alkylenediamines such as trimethylenediamine, tetramethylenediamine (putrescine), pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, and octamethylenediamine; alkylenediamines having an NH group in the alkylene skeleton such as norspermidine, spermine, and spermidine; polyamines such as putrescine; and amino sugar derivatives such as N-acetylglucosamine. Among these, more preferred are pentamethylenediamine, hexamethylenediamine, butylamine, norspermidine, spermine, spermidine, and putrescine, and particularly preferred are norspermidine, spermine, spermidine, and putrescine. Furthermore, spermine, tetramethylenediamine, and the hydrochlorides thereof are preferred in terms of being environmentally friendly and easy to put into practical use in terms of cost. As the nitrogen compounds (I) etc. and (II) etc., aliphatic monoamines and aliphatic diamines are particularly preferred.

[0020] Salts of nitrogen compounds (I) and (II) include salts of inorganic acids such as hydrogen halides and sulfuric acid. Hydrogen halides are a general term for hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide, and hydrogen astatine. Of these, the inorganic acid that forms a salt with nitrogen compound (I) is preferably hydrogen chloride.

[0021] The molecular weight of the nitrogen compounds (I) and (II) is less than 10,000. When the nitrogen compounds (I) and (II) are polymers, the weight-average molecular weight is used. From the viewpoint of promoting biodegradability, the molecular weight is preferably 5,000 or less, more preferably 500 or less, even more preferably 300 or less, particularly preferably 200 or less, especially preferably 180 or less, and most preferably 175 or less. The lower limit of the molecular weight of the nitrogen compounds (I) and (II) is not particularly limited, but is usually 90 or more, more preferably 100 or more, particularly preferably 130 or more, more preferably 150 or more, and most preferably 170 or more. In other words, the nitrogen compounds (I) and (II) are preferably low-molecular-weight compounds rather than polymers of monomers (e.g., polymers with a degree of polymerization of 100 or more). The molecular weight of the nitrogen compounds (I) and (II) can be measured by GPC (gel permeation chromatography), elemental analysis, or the like. The number of nitrogen atoms contained in the nitrogen compounds (I) and (II) is usually 1 or more, preferably 2 or more, more preferably 3 or more, and particularly preferably 4 or more, and is usually 15 or less, preferably 9 or less, more preferably 7 or less, particularly preferably 5 or less, and most preferably 4 or less. The weight ratio of nitrogen to carbon contained in the nitrogen compounds (I) and (II) is usually 5 or less, preferably 2.5 or less, more preferably 1.2 or less, even more preferably 1.0 or less, particularly preferably 0.8 or less, and most preferably 0.7 or less. On the other hand, it is usually 0.01 or more, preferably 0.05 or more, more preferably 0.15 or more, even more preferably 0.30 or more, particularly preferably 0.50 or more, especially preferably 0.60 or more, and most preferably 0.70 or more. When nitrogen compounds (I) and (II) contain secondary and tertiary amines, the content thereof is preferably low. When primary, secondary, and tertiary amines are present in nitrogen compounds (I) and (II), the ratio of primary amines to secondary and tertiary amines is usually 0.1 or more, preferably 0.4 or more, and more preferably 1.0 or more. The upper limit is not particularly limited, but is usually 5 or less, preferably 2.5 or less. The nitrogen atom concentration in the nitrogen compounds (I) and (II) is preferably 6% by weight or more, more preferably 7% by weight or more, even more preferably 10% by weight or more, particularly preferably 20% by weight or more, even more preferably 25% by weight or more, and most preferably 30% by weight or more, because the biodegradation-promoting effect is easily exhibited. On the other hand, the nitrogen atom concentration is preferably 60% by weight or less, more preferably 50% by weight or less, even more preferably 40% by weight or less, and particularly preferably 35% by weight or less, because the basicity is not too high and the activity of microorganisms is not likely to decrease. It is preferable that the nitrogen compounds (I) and (II) hardly inhibit the growth of microorganisms. Also, from the viewpoint of safety, it is preferable that they are not hazardous materials or insecticides. Furthermore, since the nitrogen compounds (I) and (II) are used to promote the biodegradation of resins, it is preferable that they do not have or have only a weak function of imparting ultraviolet absorption or light resistance to resins, such as ultraviolet absorbers or light stabilizers.

[0022] The biodegradable resin composition contains nitrogen compounds (I) and (II) in an amount of 0.1% by weight or more and 70% by weight or less. The amount of nitrogen compounds (I) and (II) contained in the biodegradable resin composition can be adjusted appropriately depending on the type of resin, the type of nitrogen compounds (I) and (II), the intended use of the biodegradable resin composition, and other factors. The content of nitrogen compounds (I) and (II) is preferably 0.5% by weight or more, particularly preferably 1% by weight or more, and most preferably 5% by weight or more. On the other hand, the content is preferably 50% by weight or less, more preferably 40% by weight or less, even more preferably 20% by weight or less, and particularly preferably 10% by weight or less. By setting the content of the nitrogen compounds (I) and (II) in the biodegradable resin composition within the above range, the composition is likely to have both biodegradability and mechanical properties when processed into a molded article. The concentration of nitrogen atoms derived from the nitrogen compounds (I) and (II) contained in the biodegradable resin composition of the present invention is preferably 50 ppm by weight or more, more preferably 70 ppm by weight or more, even more preferably 100 ppm by weight or more, particularly preferably 200 ppm by weight or more, and most preferably 500 ppm by weight or more, because the biodegradation-promoting effect is easily exhibited. On the other hand, the concentration is preferably 42% by weight or less, because the basicity is not too high and the activity of microorganisms is not likely to decrease. The particle size of the nitrogen compounds (I) and (II) is usually 500 μm or less, preferably 250 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and particularly preferably 20 μm or less, from the viewpoints of easy mixing with the biodegradable resin, reducing the likelihood of poor appearance, and facilitating the biodegradation-promoting effect. Furthermore, in particular, to obtain good mechanical properties and appearance together with the biodegradation-promoting effect, the particle size is preferably 18 μm or less, more preferably 13 μm or less, and even more preferably 10 μm or less. The lower limit is not particularly limited, but from the viewpoint of workability, it is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1.0 μm or more, and particularly preferably 3.0 μm or more.

[0023] [Polyester resin] The polyester resin contained in the biodegradable resin composition according to this embodiment is a resin having a dicarboxylic acid unit and a diol unit. By using such a resin, the biodegradability is easily improved by forming a resin composition with the nitrogen compounds (I) and (II). That is, the polyester resin is preferably a biodegradable polyester resin. Specifically, PBSA (polybutylene succinate adipate), PBSSe (polybutylene succinate sebacate), PBS (polybutylene succinate) and PBSeT (polybutylene sebacate terephthalate) are preferred. The polyester resin having dicarboxylic acid units and diol units may be copolymerized with units other than dicarboxylic acid units or diol units, but the proportion of the total amount of dicarboxylic acid units and diol units in the entire resin is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 50 mol% or more, particularly preferably 60 mol% or more, even more preferably 80 mol% or more, and most preferably 100 mol%. The polyester resin may be an aliphatic polyester resin, an aromatic polyester resin, or an aliphatic-aromatic polyester resin, with aliphatic polyester resins or aliphatic-aromatic polyester resins being preferred due to their high flexibility.

[0024] The polyester resin used in the present invention may be a single type, or two or more types of polyester resins differing in the type of structural unit, the ratio of structural units, the production method, the physical properties, etc. may be used in any combination and ratio. Furthermore, other resins may be used in combination as long as the effects of the present invention are not impaired. When other resins are used in combination, it is preferable to use a biodegradable resin in combination.

[0025] The polyester resin contained in the biodegradable resin composition according to this embodiment will be described in detail below. Each repeating unit in the polyester resin is also referred to as a compound unit corresponding to the compound from which the repeating unit is derived. For example, a repeating unit derived from an aliphatic diol is also referred to as an "aliphatic diol unit," a repeating unit derived from an aliphatic dicarboxylic acid is also referred to as an "aliphatic dicarboxylic acid unit," and a repeating unit derived from an aromatic dicarboxylic acid is also referred to as an "aromatic dicarboxylic acid unit." Furthermore, the "main structural unit" in a polyester resin usually refers to a structural unit that accounts for 80% by weight or more of the polyester resin, and may not contain any structural units other than the main structural unit.

[0026] <Polyester Resin Containing Diol Units and Dicarboxylic Acid Units> The polyester resin containing a diol unit and a dicarboxylic acid unit will now be described in detail.

[0027] The diol unit contained in the polyester resin may be aliphatic or aromatic, but is preferably aliphatic because it is easily biodegradable, and a diol unit represented by the following general formula (1) is particularly preferred. -OR 1 -O- (1) In formula (1), R 1 represents an aliphatic hydrocarbon group having 2 to 20 carbon atoms.

[0028] R 1 From the viewpoints of moldability, mechanical strength, etc., the number of carbon atoms in the aliphatic hydrocarbon group represented by the formula (I) is usually 2 or more, preferably 4 or more, and usually 20 or less, preferably 16 or less, more preferably 12 or less, and even more preferably 6 or less. A particularly preferred aliphatic hydrocarbon group is an aliphatic hydrocarbon group having 4 carbon atoms. Examples of aliphatic diols that provide the aliphatic diol unit represented by formula (1) include, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and the like, more preferably 1,4-butanediol, 1,3-propanediol, and ethylene glycol, and particularly preferably 1,4-butanediol. The polyester resin may contain one type of diol unit or two or more types of units in any combination and ratio. When the polyester resin contains multiple types of diol units, the aliphatic diol units preferably account for 30 mol % or more, more preferably 50 mol % or more of the total diol units.

[0029] The diol units contained in the polyester resin may contain aromatic diol units. Specific examples of aromatic diol components that provide aromatic diol units include xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, and bis(4-β-hydroxyethoxyphenyl)sulfonic acid. The aromatic diol component may be a derivative of an aromatic diol compound. Alternatively, the aromatic diol component may be a compound having a structure in which a plurality of aliphatic diol compounds and / or aromatic diol compounds are dehydrated and condensed with each other.

[0030] The dicarboxylic acid units contained in the polyester resin may be aliphatic or aromatic. The dicarboxylic acid units contained in the polyester resin may be one type, or two or more types of units in any combination and ratio, and may contain aliphatic dicarboxylic acid units and aromatic dicarboxylic acid units. However, from the viewpoint of biodegradability, the dicarboxylic acid units preferably contain aliphatic dicarboxylic acid units. When multiple types of dicarboxylic acid units are contained in the polyester resin, the aliphatic dicarboxylic acid units preferably account for 30 mol% or more, and more preferably 40 mol% or more, of the total dicarboxylic acid units. Meanwhile, there is no particular lower limit for the aliphatic dicarboxylic acid units, but they may not be present. When aromatic dicarboxylic acid units are contained in the polyester resin, the aromatic dicarboxylic acid units preferably account for 70 mol% or less, and more preferably 60 mol% or less, of the total dicarboxylic acid units. The number of carbon atoms in the dicarboxylic acid unit is preferably 2 to 24. From the viewpoints of biodegradability, moldability, and mechanical strength, the number of carbon atoms in the dicarboxylic acid unit is more preferably 4 or more, and on the other hand, more preferably 22 or less, even more preferably 16 or less, particularly preferably 13 or less, and most preferably 10 or less. The dicarboxylic acid unit contained in the polyester resin is preferably a dicarboxylic acid unit represented by the following general formula (2) or oxalic acid. -OC-R 2 -CO- (2) In formula (2), R 2 represents a single bond, an aliphatic hydrocarbon group having 1 to 22 carbon atoms, or an aromatic hydrocarbon group or heteroaromatic group having 4 to 8 carbon atoms.

[0031] R 2 The number of carbon atoms in the aliphatic hydrocarbon group represented by formula (2) is usually 1 or more, preferably 2 or more, and on the other hand, is preferably 22 or less, more preferably 16 or less, even more preferably 12 or less, and particularly preferably 8 or less. When the polyester resin contains two or more types of aliphatic dicarboxylic acid units represented by formula (2), the combination of the aliphatic hydrocarbon groups is preferably a combination of an aliphatic hydrocarbon group having 2 carbon atoms and an aliphatic hydrocarbon group having from 4 to 10 carbon atoms.

[0032] The aliphatic dicarboxylic acid component that provides the aliphatic dicarboxylic acid unit represented by formula (2) is not particularly limited, but the number of carbon atoms is preferably 2 or more, more preferably 4 or more, and on the other hand, preferably 24 or less, more preferably 22 or less, even more preferably 13 or less, and particularly preferably 10 or less. That is, aliphatic dicarboxylic acids having from 2 to 24 carbon atoms or derivatives thereof such as alkyl esters are preferred, aliphatic dicarboxylic acids having from 2 to 22 carbon atoms or derivatives thereof such as alkyl esters are more preferred, and aliphatic carboxylic acids having from 4 to 10 carbon atoms or derivatives thereof such as alkyl esters are even more preferred. Preferred aliphatic dicarboxylic acid units include, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, brassylic acid, undecanedioic acid, and dodecanedioic acid. Among these, adipic acid, succinic acid, and sebacic acid are preferred, succinic acid and sebacic acid are more preferred, and sebacic acid is particularly preferred.

[0033] In the polyester resin, the proportion of the above-mentioned preferred dicarboxylic acid units in all dicarboxylic acid units is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 50 mol% or more, particularly preferably 64 mol% or more, and most preferably 68 mol% or more. The upper limit is 100 mol%. By setting the preferred dicarboxylic acid proportion in the polyester resin within the above range, it is possible to obtain a biodegradable resin composition that is excellent in moldability, heat resistance, and biodegradability as well.

[0034] The polyester resin preferably contains two or more aliphatic dicarboxylic acid components, and more preferably contains two or more of the above-mentioned preferred aliphatic dicarboxylic acid components. In this case, the combination of the aliphatic dicarboxylic acid components is preferably a combination of a C4 aliphatic dicarboxylic acid or a derivative thereof with a C6 to C12 aliphatic dicarboxylic acid, and more preferably a combination of a C4 aliphatic dicarboxylic acid or a derivative thereof with a C6 to C10 aliphatic dicarboxylic acid. Specifically, the combination of the aliphatic dicarboxylic acid components preferably contains at least one of succinic acid or a derivative thereof, adipic acid or a derivative thereof, azelaic acid or a derivative thereof, sebacic acid or a derivative thereof, and brassylic acid or a derivative thereof, and more preferably a combination of two or more dicarboxylic acid components from these. As the dicarboxylic acid component to be combined with succinic acid or a derivative thereof, pimelic acid, suberic acid, azelaic acid, sebacic acid, brassylic acid, undecanedioic acid, or dodecanedioic acid or a derivative thereof is preferred, a combination with adipic acid, azelaic acid, or sebacic acid or a derivative thereof is more preferred, and a combination with sebacic acid or a derivative thereof is even more preferred. Specifically, the following polyester resins are preferred. Preferred polyester resins having succinic acid units include polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene succinate sebacate (PBSSe), and polybutylene succinate azelate (PBSAz). More preferred polyester resins have two or more dicarboxylic acid units, such as polybutylene succinate adipate (PBSA), polybutylene succinate sebacate (PBSSe), polybutylene succinate azelate (PBSAz), and polybutylene succinate brassylate (PBSBr). Among these, polybutylene succinate adipate (PBSA) is even more preferred due to the availability of raw materials. Polyester resins containing sebacic acid units are preferably polybutylene succinate sebacate (PBSSe), polybutylene sebacate terephthalate (PBSeT), and polybutylene sebacate furanoate (PBSSeF), with polybutylene succinate sebacate (PBSSe) and polybutylene sebacate terephthalate (PBSeT) being more preferred, and polybutylene succinate sebacate (PBSSe) being particularly preferred. Polyester resins containing azelaic acid units are preferably polybutylene succinate azelate (PBSAz) and polybutylene azelate terephthalate (PBAzT), etc. Polyester resins containing adipic acid units are preferably polybutylene succinate adipate (PBSA) and polybutylene adipate terephthalate (PBAT). As the polyester resin having a brassylic acid unit, polybutylene succinate brassylate (PBSBr) and polybutylene brassylate terephthalate (PBBrT) are preferred.

[0035] The dicarboxylic acid units combined with succinic acid units are preferably contained in an amount of 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on the total amount of dicarboxylic acid units, and more preferably 50 mol% or less, more preferably 45 mol% or less, and even more preferably 40 mol% or less. By copolymerizing aliphatic dicarboxylic acid units other than succinic acid units within the above range, the crystallinity of the polyester resin can be reduced, and the biodegradation rate can be increased.

[0036] The aromatic dicarboxylic acid component that provides the aromatic dicarboxylic acid unit represented by formula (2) is not particularly limited, but the number of carbon atoms therein is usually 4 or more and 8 or less, and preferably 6 or more. Specific examples thereof include a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, and a 2,5-furandiyl group.

[0037] The aromatic dicarboxylic acid component that provides the aromatic dicarboxylic acid unit represented by formula (2) is not particularly limited, but is usually an aromatic dicarboxylic acid having the above-mentioned preferred number of carbon atoms or a derivative thereof. Specific examples include phthalic acid, isophthalic acid, terephthalic acid, 2,5-furandicarboxylic acid, etc., or a derivative thereof. Among these, terephthalic acid and 2,5-furandicarboxylic acid or a derivative thereof are preferred, and 2,5-furandicarboxylic acid or a derivative thereof is more preferred.

[0038] The derivatives of aromatic dicarboxylic acids include lower alkyl esters and acid anhydrides of aromatic dicarboxylic acids having 1 to 4 carbon atoms. Specific examples of the derivatives of aromatic dicarboxylic acids include lower alkyl esters such as methyl esters, ethyl esters, propyl esters, and butyl esters of the above-mentioned aromatic dicarboxylic acids; cyclic acid anhydrides of aromatic dicarboxylic acids; and the like. Among these, dimethyl terephthalate is preferred. The polyester resin having dicarboxylic acid units may be a mixture of polyester resins having different amounts of dicarboxylic acid units. For example, it is possible to blend a polyester resin containing only the above-mentioned preferred dicarboxylic acid units as dicarboxylic acid units with a polyester resin containing dicarboxylic acid units other than these, thereby adjusting the proportion of the preferred dicarboxylic acid units in the polyester resin to fall within the above range. The polyester resin is preferably an aliphatic polyester resin containing aliphatic diol units and aliphatic dicarboxylic acid units as main constituent units (hereinafter, sometimes referred to as "aliphatic polyester resin (A)"), an aliphatic-aromatic polyester resin (B) in which at least a portion of the repeating units of the aliphatic polyester resin (A) have been replaced with aromatic compound units, or an aromatic polyester resin (polyarylate) (C) in which the repeating units of the aliphatic polyester resin (A) have been replaced with aromatic compound units.

[0039] (Aliphatic polyester resin (A)) The aliphatic polyester resin (A) is a polyester resin containing an aliphatic diol unit represented by the above formula (1) and R 2 is an aliphatic hydrocarbon group, and is preferably an aliphatic polyester resin containing an aliphatic dicarboxylic acid unit represented by the above formula (2). The aliphatic diol unit represented by formula (1) and R 2 The aliphatic dicarboxylic acid unit represented by formula (2) in which is an aliphatic hydrocarbon group is as described above. Furthermore, the aliphatic polyester resin preferred as the aliphatic polyester (A) is as described above.

[0040] As the aliphatic polyester resin (A), polybutylene succinate-based resins such as polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene succinate sebacate (PBSSe), and polybutylene succinate azelate (PBSAz) are particularly preferred.

[0041] (Aliphatic-aromatic polyester resin (B)) The aliphatic-aromatic polyester resin (B) is a resin in which at least a part of the repeating units of the above-mentioned aliphatic polyester resin (A) is replaced with an aromatic compound unit. The aliphatic-aromatic polyester resin (B) is a resin in which at least a part of the repeating units of the above-mentioned aliphatic polyester resin (A) is replaced with an aromatic compound unit. 2 Aliphatic-aromatic polyester resins containing aromatic dicarboxylic acid units represented by the above formula (2), in which is an aromatic group, are preferred.

[0042] The aliphatic diol unit represented by formula (1) and R 2 The aromatic dicarboxylic acid unit represented by formula (2) in which is an aromatic hydrocarbon group is as described above. Furthermore, the aliphatic polyesters preferred as the aliphatic-aromatic polyester (B) are as described above.

[0043] The aliphatic-aromatic polyester resin (B) may contain an aromatic diol unit. That is, the aliphatic-aromatic polyester resin (B) may be a polyester resin having an aromatic diol unit and an aliphatic dicarboxylic acid unit; an aromatic diol unit, an aliphatic dicarboxylic acid unit, and an aromatic dicarboxylic acid unit; an aliphatic diol unit, an aromatic diol unit, and an aromatic dicarboxylic acid unit; or an aliphatic diol unit, an aromatic diol unit, an aliphatic dicarboxylic acid unit, and an aromatic dicarboxylic acid unit. Specific examples of the aromatic diol component are as described above.

[0044] For the aliphatic-aromatic polyester resin (B), it is preferable to use an aromatic dicarboxylic acid component as the component that provides the aromatic compound units. In this case, the content of the aromatic dicarboxylic acid units is preferably 10 mol% or more, based on the total amount of the aliphatic dicarboxylic acid units and the aromatic dicarboxylic acid units (100 mol%), and is also preferably 80 mol% or less, more preferably 60 mol% or less, even more preferably 50 mol% or less, particularly preferably 30% or less, and most preferably 20% or less.

[0045] The aromatic dicarboxylic acid unit is preferably terephthalic acid or 2,5-furandicarboxylic acid. Specifically, the aliphatic-aromatic polyester resin (B) is preferably a polybutylene terephthalate-based resin such as polybutylene adipate terephthalate (PBAT), polybutylene succinate terephthalate (PBST), polybutylene sebacate terephthalate (PBSeT), polybutylene azelate terephthalate (PBAzT), or polybutylene brassylate terephthalate (PBBrT), or a polyfurandicarboxylate-based resin such as polybutylene adipate furanoate (PBAF), polybutylene succinate furanoate (PBSF), polybutylene sebacate furanoate (PBSeF), or polybutylene succinate sebacate furanoate (PBSSeF).

[0046] The aliphatic-aromatic polyester resin (B) is preferably a resin having succinic acid, adipic acid, or sebacic acid as a dicarboxylic acid unit.Therefore, the aliphatic-aromatic polyester resin (B) is preferably a polybutylene succinate-based resin such as PBST, PBSF, or PBSSeF; a polybutylene adipate-based resin such as PBAT, PBAF, or PBASeF; a polybutylene sebacate-based resin such as PBSeT or PBSeF; or a polybutylene azelate-based resin such as PBAzT (polybutylene azelate terephthalate) or PBAzF (polybutylene azelate furanoate), and more preferably a polybutylene succinate-aromatic dicarboxylic acid-based resin such as PBST, PBSF, or PBSSeF.

[0047] (Aromatic polyester resin (C)) The aromatic polyester resin (polyarylate) (C) is a resin in which the repeating units of the above-mentioned aliphatic polyester resin (A) are replaced with aromatic compound units. The aromatic polyester resin (C) may be a polyester resin containing an aromatic diol unit and R 2an aromatic polyester resin containing an aromatic dicarboxylic acid unit represented by the above formula (2), in which R is an aromatic hydrocarbon group; an aromatic diol unit which the aliphatic-aromatic polyester resin (B) may contain, R 2 is an aromatic hydrocarbon group, and an aromatic polyester resin containing an aromatic dicarboxylic acid unit represented by the above formula (2) and an aromatic oxycarboxylic acid unit which the aliphatic-aromatic polyester resin (B) may contain.

[0048] The units contained in the aromatic polyester resin (C) are as described above. Among the aliphatic polyester resin (A), the aliphatic-aromatic polyester resin (B), and the aromatic polyester resin (C), the aliphatic polyester resin and the aliphatic-aromatic polyester resin are preferred, and the aliphatic polyester resin is more preferred, in view of ease of biodegradability.

[0049] (3 or more functional units) The polyester resin may be a resin having an increased melt viscosity obtained by copolymerizing a trifunctional or higher aliphatic polyhydric alcohol with a trifunctional or higher aliphatic polycarboxylic acid or its acid anhydride, or a trifunctional or higher aliphatic polyoxycarboxylic acid component. When using these copolymerization components, one type may be used alone, or two or more types may be used in any combination and ratio.

[0050] Specific examples of trifunctional aliphatic polyhydric alcohols include trimethylolpropane, glycerin, etc. Specific examples of tetrafunctional aliphatic polyhydric alcohols include pentaerythritol, etc. Specific examples of trifunctional aliphatic polycarboxylic acids or their acid anhydrides include propanetricarboxylic acid or its acid anhydride, and specific examples of tetrafunctional polycarboxylic acids or their acid anhydrides include cyclopentanetetracarboxylic acid or its acid anhydride.

[0051] Trifunctional aliphatic oxycarboxylic acids are broadly classified into (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxyl group and two hydroxyl groups. Either type can be used, but from the viewpoints of moldability, mechanical strength, and appearance of molded products, (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, such as malic acid, is preferred, and malic acid is more preferred. Furthermore, tetrafunctional aliphatic oxycarboxylic acid components are broadly classified into (i) a type in which three carboxyl groups and one hydroxyl group are shared in the same molecule, (ii) a type in which two carboxyl groups and two hydroxyl groups are shared in the same molecule, and (iii) a type in which three hydroxyl groups and one carboxyl group are shared in the same molecule. While any of these types can be used, those having multiple carboxyl groups are preferred, with citric acid and tartaric acid being more preferred. These may be used alone or in any combination and ratio of two or more types.

[0052] When the polyester resin contains the above-mentioned tri- or higher functional component-derived structural units, the content thereof in the total structural units constituting the polyester resin is preferably 0.01 mol% or more, and on the other hand, preferably 5 mol% or less, more preferably 2.5 mol% or less. The polyester resin does not necessarily need to contain the above-mentioned tri- or higher functional component-derived structural units.

[0053] (Method of producing polyester resin) The polyester resin containing diol units and dicarboxylic acid units can be produced by a known method for producing polyester resins. The polycondensation reaction can be carried out under suitable conditions that have been conventionally used, and is not particularly limited. Usually, the degree of polymerization is further increased by carrying out a reduced pressure operation after the esterification reaction has proceeded.

[0054] When a diol component forming a diol unit and a dicarboxylic acid component forming a dicarboxylic acid unit are reacted during the production of a polyester resin, the amounts of the diol component and the dicarboxylic acid component used are adjusted so that the polyester resin produced has the desired composition. Usually, the diol component and the dicarboxylic acid component react in substantially equimolar amounts, but the diol component is usually used in an excess of 1 mol % to 20 mol % over the dicarboxylic acid component because it is distilled off during the esterification reaction.

[0055] When components such as polyfunctional component units are copolymerized with a polyester resin, the corresponding compounds (monomers or oligomers) may be reacted to obtain the desired composition for each of the polyfunctional component units. In this case, there are no limitations on the timing or method of introducing these components into the reaction system, and any method is acceptable as long as the polyester resin can be produced.

[0056] The timing of introducing the compound that forms the polyfunctional component unit into the polyester resin may be such that it is charged simultaneously with other monomers or oligomers at the initial stage of polymerization, or may be such that it is charged after the transesterification reaction and before the pressure reduction is started. However, charging it simultaneously with other monomers or oligomers is preferred in terms of simplifying the process.

[0057] Polyester resins are usually produced in the presence of a catalyst. Any catalyst that can be used in the production of known polyester resins can be selected as the catalyst, as long as it does not significantly impair the effects of the present invention. Suitable examples of such catalysts include metal compounds of germanium, titanium, zirconium, hafnium, antimony, tin, magnesium, calcium, zinc, etc. Among these, germanium compounds and titanium compounds are preferred.

[0058] Examples of germanium compounds that can be used as catalysts include organic germanium compounds such as tetraalkoxygermanium, and inorganic germanium compounds such as germanium oxide and germanium chloride. Among these, germanium oxide, tetraethoxygermanium, tetrabutoxygermanium, and the like are preferred in terms of price, availability, and the like, with germanium oxide being particularly suitable.

[0059] Examples of titanium compounds that can be used as catalysts include organic titanium compounds such as tetraalkoxytitanium compounds such as tetrapropyl titanate, tetrabutyl titanate, tetraphenyl titanate, etc. Among these, tetrapropyl titanate, tetrabutyl titanate, etc. are preferred in terms of price, availability, etc.

[0060] In addition, other catalysts may be used in combination as long as the object of the present invention is not impaired. The catalysts may be used alone or in any combination and ratio of two or more.

[0061] The amount of catalyst used is arbitrary as long as it does not significantly impair the effects of the present invention, but is usually 0.0005% by weight or more, more preferably 0.001% by weight or more, and usually 3% by weight or less, preferably 1.5% by weight or less, based on the amount of monomer used. By setting the catalyst amount within the above range, sufficient catalytic effect can be obtained while suppressing production costs, and coloration of the obtained polymer or deterioration of hydrolysis resistance can be suppressed.

[0062] The timing of introducing the catalyst is not particularly limited as long as it is before the polycondensation reaction, and it may be introduced when the raw materials are charged or when the pressure reduction is started.

[0063] The reaction conditions, such as temperature, polymerization time, and pressure, for the esterification reaction and / or transesterification reaction between the dicarboxylic acid component and the diol component may be any as long as they do not significantly impair the effects of the present invention. The reaction temperature for the esterification reaction and / or transesterification reaction between the dicarboxylic acid component and the diol component is usually 150°C or higher, preferably 180°C or higher, and usually 260°C or lower, preferably 250°C or lower. The reaction is usually carried out under an inert atmosphere such as nitrogen or argon. The reaction pressure is usually normal pressure to 10 kPa, with normal pressure being preferred. The reaction time is usually 1 hour or longer and usually 10 hours or shorter, preferably 6 hours or shorter, and more preferably 4 hours or shorter. By setting the reaction conditions within the above ranges, gelation due to excessive formation of unsaturated bonds is suppressed, and the degree of polymerization can be controlled.

[0064] The pressure in the polycondensation reaction after the esterification reaction and / or transesterification reaction between the dicarboxylic acid component and the diol component is usually 0.01 × 10 3 Pa or more, preferably 0.03 x 10 3 Pa or more, typically 1.4 × 10 3 Pa or less, preferably 0.4×10 3 It is desirable to carry out the reaction under a vacuum of 100 Pa or less. The reaction temperature is usually 150°C or higher, preferably 180°C or higher, and usually 260°C or lower, preferably 250°C or lower. The reaction time is usually 2 hours or longer, and usually 15 hours or shorter, preferably 10 hours or shorter. By setting the reaction conditions within the above ranges, gelation due to excessive production of unsaturated bonds can be suppressed, and the degree of polymerization can be controlled.

[0065] A chain extender such as a carbonate compound or a diisocyanate compound can also be used during the production of the polyester resin. In this case, the amount of the chain extender is typically 10 mol% or less, preferably 5 mol% or less, and more preferably 3 mol% or less, as a proportion of carbonate bonds or urethane bonds relative to all structural units constituting the polyester resin. From the viewpoint of the biodegradability of the biodegradable resin composition according to this embodiment, the carbonate bond content is preferably less than 1 mol%, more preferably 0.5 mol% or less, and even more preferably 0.1 mol% or less, relative to all structural units constituting the polyester resin. The urethane bond content is preferably 0.5 mol% or less, more preferably 0.3 mol% or less, even more preferably 0.12 mol% or less, and particularly preferably 0.05 mol% or less. When this amount is converted into weight % relative to the polyester resin composition, it is preferably 0.9 wt% or less, more preferably 0.5 wt% or less, even more preferably 0.2 wt% or less, and particularly preferably 0.1 wt% or less. In particular, by setting the urethane bond amount within the above range, smoke and odor caused by decomposition of the urethane bond are suppressed in the film formation process, etc., and film breakage due to foaming in the molten film is suppressed, so that molding stability can be ensured. 1 H-NMR and 13 It can be calculated from the results of measurements using NMR (nuclear magnetic resonance spectroscopy) such as C-NMR.

[0066] Specific examples of carbonate compounds as chain extenders include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, dicyclohexyl carbonate, etc. In addition, carbonate compounds derived from hydroxy compounds such as phenols and alcohols can also be used.

[0067] Specific examples of the diisocyanate compound include known diisocyanates such as 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, 2,4,6-triisopropylphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, and tolidine diisocyanate. is shown.

[0068] Other chain extenders such as dioxazoline and silicate esters may also be used. Specific examples of silicate esters include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxysilane.

[0069] High molecular weight polyester resins using these chain extenders (coupling agents) can also be produced using conventionally known techniques. The chain extender is usually added to the reaction system in a homogeneous molten state without a solvent after the polycondensation is completed, and reacted with the polyester obtained by polycondensation.

[0070] More specifically, a polyester resin with substantially hydroxyl terminal groups, obtained by catalytically reacting a diol component with a dicarboxylic acid component, can be reacted with a chain extender to obtain a polyester resin with a higher molecular weight. Prepolymers with a weight-average molecular weight of 20,000 or more can be produced by using a small amount of chain extender without being affected by residual catalyst, even under harsh conditions such as in a molten state, and thus can produce high-molecular-weight polyester resins without forming gels during the reaction. The weight-average molecular weight (Mw) of a polyester resin is determined by gel permeation chromatography (GPC) using chloroform as the solvent at 40°C, converted into a monodisperse polystyrene equivalent.

[0071] Therefore, for example, when the polyester resin is further increased in molecular weight using the above-mentioned diisocyanate compound as a chain extender, the weight-average molecular weight of the prepolymer is preferably 20,000 or more, more preferably 40,000 or more. A high weight-average molecular weight requires only a small amount of diisocyanate compound to increase the molecular weight, making it less likely that the heat resistance will decrease. In this way, a polyester resin having urethane bonds with a linear structure linked via urethane bonds derived from the diisocyanate compound is produced.

[0072] The pressure during chain extension is preferably 0.01 MPa or more, more preferably 0.05 MPa or more, and even more preferably 0.07 MPa or more. On the other hand, the pressure during chain extension is preferably 1 MPa or less, more preferably 0.5 MPa or less, and even more preferably 0.3 MPa or less. The pressure during chain extension is most preferably normal pressure.

[0073] The reaction temperature during chain extension is preferably 100° C. or higher, more preferably 150° C. or higher, even more preferably 190° C. or higher, and particularly preferably 200° C. or higher. On the other hand, the reaction temperature during chain extension is preferably 250° C. or lower, more preferably 240° C. or lower, and even more preferably 230° C. or lower. By setting the reaction temperature within the above range, the reaction liquid is maintained at an appropriate viscosity, enabling a uniform reaction, allowing the reaction liquid to be sufficiently stirred without requiring high stirring power, and also preventing the polyester resin from gelling or decomposing.

[0074] The time for the chain extension reaction is preferably 0.1 minutes or more, more preferably 1 minute or more, and even more preferably 5 minutes or more. On the other hand, the time for the chain extension reaction is preferably 5 hours or less, more preferably 1 hour or less, even more preferably 30 minutes or less, and particularly preferably 15 minutes or less. By setting the chain extension time within the above range, it is possible to extend the chain to the desired molecular weight and also to prevent the polyester resin from gelling or decomposing.

[0075] The polyester resin contained in the biodegradable resin composition according to this embodiment may be a single constituent unit or two or more constituent units in any combination and ratio, preferably a polyester resin having three or more constituent units, more preferably a polyester resin having two or more dicarboxylic acid units and one or more diol units. The diol units and dicarboxylic acid units may be derived from compounds derived from petroleum or from compounds derived from plant raw materials, but it is preferable to use compounds derived from plant raw materials because this is environmentally friendly.

[0076] In addition, when an optical isomer exists in the aromatic compound component that provides the aromatic compound unit, any of the D-isomer, L-isomer, and racemic isomer may be used. In addition, the aromatic compound component is not limited to the above examples as long as it can provide an aromatic compound unit. One type of aromatic compound component may be used alone, or two or more types may be used in any combination and ratio.

[0077] <Physical properties of polyester resin> The glass transition temperature (Tg) of the polyester resin according to the present invention is preferably 40°C or lower. When biodegrading a polyester resin, a glass transition temperature lower than the temperature of the environment in which the polyester resin is placed, such as the ocean, loosens the crystalline structure of the polyester resin, allowing the molecular main chain to rotate and vibrate, which is thought to facilitate biodegradation. Therefore, the glass transition temperature of the polyester resin is more preferably 30°C or lower, even more preferably 25°C or lower, particularly preferably 20°C or lower, even more preferably 0°C or lower, and most preferably -20°C or lower. From the perspective of ease of molding, the lower limit is preferably -100°C or higher, more preferably -60°C or higher, and even more preferably -40°C or higher. The glass transition temperature can be measured by the following method. 10 mg of each resin was placed in an aluminum sample container to serve as a measurement sample. Next, using a DSC, the temperature was raised from -100°C to 160°C at a rate of 10°C / min under a nitrogen atmosphere to obtain a DSC chart. The glass transition temperature was determined from the baseline shift present on the lower side of the peak indicating the melting point on this chart. Specifically, the intersection of the baseline on the lower side and the inflection point was taken as the glass transition temperature.

[0078] The acid value of the polyester resin according to the present invention is preferably 250 eq / t or less. A low acid value of the polyester resin makes it less susceptible to hydrolysis and provides excellent storage stability. Therefore, the acid value of the polyester resin is more preferably 100 eq / t or less, even more preferably 80 eq / t or less, particularly preferably 50 eq / t or less, even more preferably 40 eq / t or less, and most preferably 30 eq / t or less. The acid value of the polyester resin is usually 19 eq / t or more, preferably 20 eq / t or more, more preferably 23 eq / t or more, even more preferably 26 eq / t or more, particularly preferably 28 eq / t or more, and most preferably 29 eq / t or more. The acid value can be measured by the following method. Accurately weigh out 0.4 g of resin, add 25 mL of benzyl alcohol, and dissolve by heating to 195°C and stirring. Once the resin is dissolved, cool the container containing the resin solution in an ice bath and add 2 mL of ethanol to the container. Titrate using a 0.01 N solution of sodium hydroxide in benzyl alcohol (the titer is A (ml)). Next, repeat the same measurement using only benzyl alcohol to obtain the blank value (B (ml)). Calculate the acid value using the following formula: Terminal acid value (eq / t)=(AB)×F×10 / W A (ml): Measured titer amount B (ml): Blank titration volume F: 0.01N NaOH benzyl alcohol your factor W(g): Sample weight

[0079] The reduced viscosity η of the polyester resin according to the present invention at 30°Csp / c is preferably 0.5 dL / g or more. The reduced viscosity of the polyester resin may be appropriately selected depending on the application, processing method, etc. Specifically, the reduced viscosity of the resin at 30°C is more preferably 0.8 dL / g or more, even more preferably 1.0 dL / g or more, particularly preferably 1.2 dL / g or more, even more preferably 1.5 dL / g or more, and most preferably 1.8 dL / g or more, and on the other hand, it is preferably 4.0 dL / g or less, more preferably 3.0 dL / g or less, even more preferably 2.5 dL / g or less, particularly preferably 2.3 dL / g or less, and most preferably 1.9 dL / g or less. By setting the reduced viscosity of the polyester resin within the above range, it is possible to ensure the mechanical properties when processed into a molded article, and also to ensure that the melt viscosity of the biodegradable resin composition during molding processing is at a level that does not place an excessive load on molding machines such as extruders and injection machines, thereby ensuring productivity.

[0080] The reduced viscosity of a polyester resin can usually be measured by the following method. First, the resin is dissolved in a solvent to prepare a resin solution with a concentration c (g / dL). Next, using a capillary viscometer (Ubbelohde viscometer), the passage time t0 of the solvent and the passage time t of the resin solution are measured at a temperature of 30.0°C ± 0.1°C, and the relative viscosity η is calculated based on the following formula (i): rel Then, the relative viscosity η rel From the above, the specific viscosity η is calculated based on the following formula (ii): sp Ask for. η rel =t / t0 (i) η sp =η rel -1 (ii) The obtained specific viscosity η sp Dividing by the concentration c (g / dL) gives the reduced viscosity η sp / c can be calculated. Generally, the higher this value, the larger the molecular weight.

[0081] The molecular weight of the polyester resin according to the present invention is usually measured by gel permeation chromatography (GPC). From the viewpoints of moldability and mechanical strength, the resin contained in the biodegradable resin composition according to this embodiment preferably has a weight-average molecular weight (Mw) in the following range, using monodisperse polystyrene as the standard. That is, the molecular weight of the resin is preferably 50,000 or more, more preferably 80,000 or more, even more preferably 100,000 or more, particularly preferably 150,000 or more, and most preferably 160,000 or more. On the other hand, it is preferably 1,000,000 or less, more preferably 500,000 or less, even more preferably 400,000 or less, particularly preferably 300,000 or less, particularly preferably 200,000 or less, more preferably 180,000 or less, and most preferably 170,000 or less.

[0082] The melt flow rate (MFR) of the polyester resin according to the present invention can be evaluated based on the value measured at 190°C under a load of 2.16 kg according to JIS K 7210 (1999). From the viewpoints of moldability and mechanical strength, the MFR of the resin contained in the biodegradable resin composition according to the present embodiment is preferably within the following range. That is, it is preferably 0.1 g / 10 min or more, and more preferably 1 g / 10 min or more. On the other hand, the MFR of the resin is preferably 100 g / 10 min or less, more preferably 80 g / 10 min or less, even more preferably 50 g / 10 min or less, particularly preferably 40 g / 10 min or less, and most preferably 30 g / 10 min or less. The MFR of the resin can be adjusted by the molecular weight, etc.

[0083] By setting the melting point of the polyester resin according to the present invention within the following range, good moldability can be ensured. That is, the melting point of the resin is preferably 60°C or higher, more preferably 70°C or higher, even more preferably 75°C or higher, and particularly preferably 80°C or higher, and on the other hand, it is preferably 270°C or lower, more preferably 200°C or lower, even more preferably 150°C or lower, particularly preferably 140°C or lower, even more preferably 130°C or lower, and most preferably 100°C or lower. Note that when the resin has multiple melting points, it is preferable that at least one of the melting points is within the above range. The entropy of fusion (ΔHm) of the polyester resin according to the present invention is preferably 20 mJ / mg or more, more preferably 30 mJ / mg or more, even more preferably 35 mJ / mg or more, and particularly preferably 40 mJ / mg or more, since both moldability and biodegradability can be achieved. In addition, the entropy of fusion is usually preferably 300 mJ / mg or less, more preferably 200 mJ / mg or less, and even more preferably 100 mJ / mg or less.

[0084] The tensile modulus of the polyester resin according to the present invention is preferably 30 MPa or more, more preferably 70 MPa or more, even more preferably 100 MPa or more, and particularly preferably 150 MPa or more, so as to ensure good moldability and impact strength, and is preferably 900 MPa or less, more preferably 800 MPa or less, even more preferably 600 MPa or less, particularly preferably 500 MPa or less, more preferably 300 MPa or less, and most preferably 280 MPa or less. The resin composition containing the nitrogen compounds (I) and (II) is not particularly limited, and may be a resin other than the above-mentioned preferred resins, as long as biodegradability is improved by forming it into a resin composition. The tensile modulus is measured according to JIS K 7127:1999. Specifically, a heat-pressed sheet of each resin is prepared as follows: A metal frame with a release-treated surface is placed on a 150 mm × 150 mm PTFE tape. 1.6 g of resin is weighed inside the metal frame, and a 150 mm × 150 mm PTFE tape is placed on top of it. The resin sandwiched between the PTFE tape is placed between two iron plates (160 mm × 160 mm, 3 mm thick). The resin is then heat-pressed using a heat press and then cold-pressed using a cooling press to obtain a 70 mm × 70 mm × 0.2 mm thick heat-pressed sheet. The heat press temperature is 180°C, and the heat press time is 2 minutes for preheating and 2 minutes for pressing. The cold press temperature is 20°C, and the cold press time is 2 minutes. The resulting heat-pressed sheet is punched into a No. 8 dumbbell shape to prepare a test specimen. The test piece is stretched uniaxially at a rate of 50 mm / min, and the initial slope of the resulting stress-strain curve is taken as the tensile modulus. The tensile elongation at break of the polyester resin according to the present invention is preferably 200% or more, more preferably 400% or more, even more preferably 500% or more, particularly preferably 700% or more, and most preferably 800% or more, in order to ensure good processability. In addition, in order to facilitate handling, the elongation is preferably 20,000% or less, more preferably 1,500% or less, even more preferably 1,300% or less, particularly preferably 1,000% or less, and most preferably 900% or less. The tensile elongation at break is measured by a method conforming to JIS K 7127. Specifically, similar to the measurement of tensile modulus, a test piece is punched into a No. 8 dumbbell shape to prepare a test piece, and this test piece is uniaxially elongated at a temperature of 23°C and a test speed of 50 mm / min to measure the tensile elongation at break.

[0085] [Other ingredients] The biodegradable resin composition according to this embodiment may contain other components such as various additives, such as fillers, plasticizers, antistatic agents, antioxidants, light stabilizers, ultraviolet absorbers, dyes, pigments, hydrolysis inhibitors, crystal nucleating agents, antiblocking agents, weathering agents, heat stabilizers, flame retardants, release agents, antifogging agents, surface wetting improvers, incineration aids, dispersing aids, various surfactants, slip agents, freshness-preserving agents, antibacterial agents, etc., as long as the effects of the present invention are not significantly impaired. When these components are contained, only one type of component may be contained, or two or more types may be contained.

[0086] When other components are contained in the biodegradable resin composition, the content of these components is preferably 40% by weight or less, more preferably 20% by weight or less, even more preferably 10% by weight or less, and particularly preferably 5% by weight or less, relative to the total amount of the biodegradable resin composition, from the viewpoint of not impairing the properties of the biodegradable resin composition. Note that there is no particular lower limit on the content of these other components.

[0087] [Method for producing biodegradable resin composition] The method for producing the biodegradable resin composition according to this embodiment is not particularly limited. The biodegradable resin composition according to this embodiment can be obtained by mixing a resin, a compound such as nitrogen compounds (I) and (II), and, if necessary, other resins and other components. The biodegradable resin composition can be produced, for example, by mixing or kneading the components in a predetermined ratio simultaneously or in any order using a mixer such as a tumbler, V-type blender, Nauta mixer, Banbury mixer, kneading roll, or extruder, and preferably further melt-kneading. Alternatively, the composition can be produced by dissolving or dispersing the resin and a compound such as nitrogen compounds (I) and (II) in a solvent and then removing the solvent.

[0088] From the viewpoint of improving the biodegradability and biodegradation rate of the biodegradable resin composition, particularly the initial biodegradation rate, it is preferable that the nitrogen compounds (I) and (II) are uniformly dispersed in the biodegradable resin composition. Therefore, the biodegradable resin composition is preferably produced by kneading, more preferably by melt kneading.

[0089] The kneader used for kneading may be a melt kneader. The extruder may be either a twin-screw extruder or a single-screw extruder, with a twin-screw extruder being more preferred.

[0090] When melt-kneading is carried out, the melt-kneading temperature is preferably 80° C. or higher, more preferably 100° C. or higher, and on the other hand, preferably 220° C. or lower, more preferably 210° C. or lower. Within this temperature range, melt-kneading can be carried out in a short time, deterioration of the resin and deterioration of color tone due to carbonization of the nitrogen compounds (I) and (II) are unlikely to occur, and a resin composition having better practical physical properties such as impact resistance and moist heat resistance is likely to be obtained. The melt-kneading time is not particularly limited as long as the nitrogen compounds (I) and (II) can be uniformly dispersed in the biodegradable resin, but it is also desirable to carry out the melt-kneading for a short time so that the resin is less likely to deteriorate, etc. Specifically, the melt-kneading time is preferably 10 seconds or more, more preferably 30 seconds or more, and on the other hand, preferably 20 minutes or less, more preferably 15 minutes or less.

[0091] [Biodegradability of biodegradable resin composition] The biodegradable resin composition according to this embodiment is biodegradable. It is particularly preferable that the resin composition of the present invention be biodegradable in seawater, where resins are considered difficult to biodegrade (marine biodegradable resin composition). The reason why the resin composition of the present invention exhibits biodegradability even in seawater is presumed to be as follows: Generally, the amount and variety of microorganisms in seawater is low. Therefore, it is presumed that mold and other organisms do not easily grow in seawater, and biofilm formation is important for biodegradation in seawater. Furthermore, seawater is an environment lacking in nitrogen, an element essential for sustaining life. Therefore, it is presumed that the presence of low-molecular-weight nitrogen compounds such as polyamines promotes cell proliferation and activation of microorganisms in seawater, promoting biofilm formation and enhancing biodegradability. Furthermore, when a resin is heated to a temperature above its glass transition temperature, its molecular chains become more mobile. For this reason, resins with low glass transition temperatures are presumed to be more susceptible to biodegradation. In particular, resins with a glass transition temperature of 40°C or lower are thought to be more susceptible to biodegradation in seawater by nitrogen compounds (I) and (II). In this specification, the degree of biodegradation is calculated as the ratio of biological oxygen demand (BOD) to theoretical oxygen demand (ThOD). For example, biodegradation in seawater is measured in accordance with ISO 14851:1999 (Plastics - Determination of the ultimate degree of aerobic biodegradation in aqueous media - Method by measurement of oxygen consumption using a closed respirometer); biodegradation in soil is measured in accordance with ISO 17556:2003 (Plastics - Determination of the ultimate degree of aerobic biodegradation in soil by measurement of oxygen consumption or carbon dioxide evolution using a respirometer).

[0092] The biodegradability of the biodegradable resin composition according to this embodiment, at any time point after the start of a biodegradation test, preferably exceeds 1.0 times the biodegradability of a composition obtained by excluding the nitrogen compounds (I) and (II) from the biodegradable resin composition according to this embodiment (hereinafter, this may be referred to as the "reference composition"). (Hereinafter, the increase in biodegradability relative to the biodegradability of the reference composition may be referred to as the "biodegradation improvement rate.") Specifically, on the 15th day after the start of a biodegradation test according to the above-mentioned standard, the biodegradation improvement rate of the biodegradable resin composition according to this embodiment is more preferably 1.1 times or more, even more preferably 1.6 times or more, particularly preferably 2.0 times or more, even more preferably 2.8 times or more, particularly preferably 3.4 times or more, and most preferably 10.0 times or more. In this specification, high biodegradability means that the degree of improvement in biodegradability of the biodegradable resin composition at any time point after the start of the biodegradability test is 1.6 times or more, 2.0 times or more, 2.8 times or more, 3.4 times or more, or 10.0 times or more.

[0093] [Biodegradation method for polyester resin] The method for biodegrading a polyester resin of the present invention is characterized in that the polyester resin has a glass transition temperature of 40°C or lower, and the polyester resin is biodegraded in seawater in the presence of one or more compounds selected from nitrogen compounds represented by the following general formula (I) and salts thereof, each having a molecular weight of less than 10,000:

[0094] [ka]

[0095] (In the formula, R, R', and R'' each independently represent a hydrogen atom or a monovalent organic group which may have substituents that do not form a ring structure with each other.) The polyester resin, nitrogen compound (I), and other compounds suitable for this method are as described above.

[0096] [Molded body] The biodegradable resin composition according to this embodiment can be molded by various molding methods applicable to general-purpose plastics. Examples of molding methods include compression molding (compression molding, laminate molding, stampable molding), injection molding, extrusion molding, coextrusion molding (film molding by inflation or T-die methods, laminate molding, pipe molding, wire / cable molding, molding of profiled materials), heat press molding, blow molding (various blow moldings), calendar molding, solid molding (uniaxial stretch molding, biaxial stretch molding, roll molding, stretch-oriented nonwoven fabric molding, thermoforming (vacuum forming, pressure forming), plastic processing, powder molding (rotational molding), and various nonwoven fabric moldings (dry method, adhesive method, entanglement method, spunbonding method, etc.)). Among these, injection molding, extrusion molding, compression molding, or heat press molding is preferred, and injection molding or extrusion molding is more preferred. Specific shapes of the composition are preferably sheets, films, or containers.

[0097] Furthermore, a molded article obtained by molding the biodegradable resin composition according to this embodiment can be subjected to various secondary processing steps in order to impart surface functions such as chemical functions, electrical functions, magnetic functions, mechanical functions, friction / wear / lubrication functions, optical functions, thermal functions, biocompatibility, etc. Examples of secondary processing steps include embossing, painting, bonding, printing, metallizing (plating, etc.), machining, and surface treatments (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.).

[0098] [Application] The biodegradable resin composition according to this embodiment is suitable for a wide range of applications, such as packaging materials for packaging liquid, powdered, or solid materials, such as various foods, medicines, and miscellaneous goods, as well as agricultural and construction materials. Specific applications include injection-molded articles (e.g., trays for fresh food, fast-food containers, coffee capsule containers, cutlery, outdoor leisure products, etc.), extrusion-molded articles (e.g., films, sheets, fishing lines, fishing nets, vegetation nets, sheets for secondary processing, water-retaining sheets, etc.), and blown-molded articles (e.g., bottles). Further examples include agricultural films, coating materials, fertilizer coating materials, seedling pots, laminated films, plates, stretched sheets, monofilaments, nonwoven fabrics, flat yarns, staples, crimped fibers, creased tape, split yarns, composite fibers, blown bottles, shopping bags, garbage bags, compost bags, cosmetic containers, detergent containers, bleach containers, ropes, binding materials, sanitary cover stock materials, insulated boxes, cushioning films, multifilaments, synthetic paper, and medical applications such as surgical thread, sutures, artificial bones, artificial skin, DDS such as microcapsules, wound dressings, etc. The molded article is particularly suitable as food containers such as food packaging films, trays for fresh food, fast food containers, and lunch boxes. [Example]

[0099] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. The values ​​of various production conditions or evaluation results in the following examples represent preferred upper or lower limit values ​​in the embodiments of the present invention, and preferred ranges may be defined by combining the above-mentioned upper or lower limit values ​​with the values ​​of the following examples or values ​​between the examples.

[0100] <Polyester resin> (PBSSe) 1,4-butanediol (100.1 g), succinic acid (75.0 g), sebacic acid (32.1 g), trimethylolpropane (0.34 g), and titanium tetrabutoxide (0.50 g) were heated under nitrogen at 200°C for 2 hours with stirring. The temperature was then raised to 250°C under reduced pressure, and the reaction was continued for 5 hours and 15 minutes. The resulting polymer was extracted into water in the form of a strand and cut into pellets of PBSSe. The reduced viscosity of PBSSe was measured according to the following measurement method and was found to be 1.8 dL / g. The glass transition temperature was -30°C and the acid value was 28 eq / t, both of which were also measured according to the following measurement methods. 1 The molar ratio of succinic acid units to sebacic acid units determined by 1 H-NMR (nuclear magnetic resonance spectroscopy) was 80 / 20.

[0101] (PBSA) BioPBS TM FD92PB (PTT MCC Biochem) The reduced viscosity of the PBSA was measured according to the following method and found to be 2.3 dL / g. The glass transition temperature was −40° C. and the acid value was 29 eq / t, both of which were also measured according to the following methods.

[0102] (PBSeT) 1,4-butanediol (85.10 g), sebacic acid (63.70 g), terephthalic acid (52.30 g), trimethylolpropane (0.27 g), and titanium tetrabutoxide (0.53 g) were heated under nitrogen at 220°C for 2 hours with stirring. The temperature was then raised to 240°C under reduced pressure, and the reaction continued for 3 hours and 15 minutes. The resulting polymer was extracted into water in the form of a strand and cut to obtain pellets of PBSeT. 1 The molar ratio of sebacic acid-derived units to terephthalic acid-derived units determined by H-NMR (nuclear magnetic resonance spectroscopy) was 50 / 50. The reduced viscosity, glass transition temperature, and acid value, all of which were measured according to the following methods, were 1.32 dL / g, -40°C, and 24 eq / t, respectively.

[0103] (PHBH) Kaneka's biodegradable polymer "Green Planet TM The glass transition temperature was 0°C and the acid value was 18 eq / t.

[0104] (PLA) Ingeo 4032D (NatureWorks) was evaluated. The reduced viscosity was 2.18 dL / g and the glass transition temperature was 55-60°C (catalog value).

[0105] <Nitrogen compounds (I), etc. and (II), etc.> The compounds listed in Table 1 were used.

[0106] <Other compounds> Polyethyleneimine (weight average molecular weight 66,000, nitrogen atom concentration 33% by weight) N,N'-ethylenebisoleamide (molecular weight 588, nitrogen atom concentration 5% by weight) Glucose (molecular weight 180) starch

[0107] (Method for measuring reduced viscosity) A resin solution was prepared by dissolving the resin in a 1:1 (weight ratio) mixed solvent of phenol and tetrachloroethane to a concentration of 0.5 g / dL. The reduced viscosity of the resin solution was then measured at 30°C using an Ubbelohde viscometer, and the reduced viscosity was calculated based on the results. (Method for measuring glass transition temperature) 10 mg of each resin was placed in an aluminum sample container to serve as a measurement sample. Next, using a Hitachi High-Tech Science DSC6220, the temperature was raised from -100°C to 160°C at a rate of 10°C / min under a nitrogen atmosphere to obtain a DSC chart. The glass transition temperature was determined from the baseline shift present on the lower temperature side of the peak indicating the melting point in this chart. Specifically, the intersection of the baseline on the lower temperature side and the inflection point was taken as the glass transition temperature. (Method for measuring acid value) 0.4 g of resin was weighed out, 25 mL of benzyl alcohol was added, and the mixture was heated to 195°C and stirred to dissolve. Once the resin was dissolved, the container containing the resin solution was cooled in an ice bath, and 2 mL of ethanol was added to the container. Titration was performed using a 0.01 N sodium hydroxide solution in benzyl alcohol using a Mitsubishi Chemical Corporation automatic titration device "GT100" (titration amount is A (ml)). Next, the same measurement was carried out using only benzyl alcohol, and this was used as the blank value (B (ml)). The acid value was calculated using the following formula: Terminal acid value (eq / t)=(AB)×F×10 / W A (ml): Measured titer amount B (ml): Blank titration volume F: 0.01N NaOH benzyl alcohol your factor W(g): Sample weight

[0108] <Comparative Example 1> PBSSe was pulverized to a particle size (sieving method) of 250 μm or less to obtain a pulverized resin.

[0109] <Comparative Example 4> PBSA was pulverized to a particle size (sieving method) of 250 μm or less to obtain a pulverized resin.

[0110] <Comparative Example 5> PBSeT was pulverized to a particle size (sieving method) of 250 μm or less to obtain a pulverized resin.

[0111] <Comparative Example 6> PHBH was pulverized to a particle size (sieving method) of 250 μm or less to obtain a pulverized resin.

[0112] <Example 1, Reference Examples 2 to 4, Examples 5 and 6, Reference Examples 7 to 12, Example 13, Reference Example 1, Comparative Examples 2, 3, 7 and 8> The crushed resin and the nitrogen compounds (I) and (II) were mixed in the proportions shown in Table 1 to a total of 30 mg.

[0113] <Examples 14 and 15> The ground resin and nitrogen compounds (I) and (II) were blended in the proportions shown in Table 1, then placed in a small twin-screw kneader (DSM's "Xplore MC15 Micro Compounder") and melt-kneaded at 150°C for 3 minutes under a nitrogen atmosphere. The resulting kneaded product was ground to a particle size (sieving method) of 250 µm or less, to obtain a biodegradable resin composition.

[0114] <Method for measuring biodegradability> The biodegradability of the resins or resin compositions obtained in Examples 1 to 13, Reference Example 1, and Comparative Examples 1 to 8 was measured in accordance with ISO 14851 as follows. 100 mL of a mixture of standard test culture medium and seawater prepared according to a method compliant with ISO 14851 was added to a 510 mL brown bottle containing 30 mg of sample. A pressure sensor (WTW, OxiTop (registered trademark)-C type) was attached to the brown bottle, and the test solution was stirred with a stirrer for 15 days in a constant temperature environment of 25°C. The biodegradability (%) was calculated based on the BOD measurement. The biodegradability was evaluated as the improvement (fold) in biodegradability when the nitrogen compound of the present invention was added relative to the biodegradability of the biodegradable resin. The results are shown in Table 1. In the table, simple mixing is described as "added." Furthermore, the biodegradability of the resin compositions obtained in Examples 14 and 15 was measured in accordance with ISO 14851 as in Examples 1 to 13, as follows. 100 mL of a mixture of standard test culture medium and seawater prepared according to a method compliant with ISO 14851 was added to a 510 mL brown bottle containing 30 mg of sample. A pressure sensor (WTW, OxiTop (registered trademark)-C type) was attached to the brown bottle, and the test solution was stirred with a stirrer for 20 days in a constant temperature environment of 25°C. The biodegradability (%) was calculated based on the BOD measurement. The biodegradability was evaluated as the improvement (fold) in biodegradability when the nitrogen compound of the present invention was added relative to the biodegradability of the biodegradable resin. The results are shown in Table 1. In the table, cases where the material was kneaded are indicated as "kneaded."

[0115] [Table 1]

[0116] Comparisons of Examples 1, 5, and 14 with Comparative Example 1, comparisons of Example 6 with Comparative Example 4, and comparisons of Example 13 with Comparative Example 5 confirm that the biodegradability of the resin is significantly improved by the nitrogen compounds (I) and (II). In contrast, Comparative Examples 2, 3, 7, and 8, which contained compounds other than nitrogen compounds (I) and (II), showed a decrease in biodegradability. The decrease in biodegradability with polyethyleneimine is thought to be due to the fact that polyethyleneimine has a large molecular weight, making it difficult for the polyethyleneimine itself to biodegrade and thus difficult to generate amino groups through degradation, and that polyethyleneimine present near the surface of the biodegradable resin composition inhibits contact of the resin with microorganisms. That is, nitrogen compounds (I) and (II) have a small molecular weight, making them easily biodegradable and easily generating amino groups through degradation. Therefore, nitrogen compounds (I) and (II) present near the surface of the biodegradable resin composition are unlikely to interfere with contact of the resin with microorganisms, which is thought to improve biodegradability. The decrease or low level of promotion of biodegradability with N,N'-ethylenebisoleamide and glucose is thought to be due to the fact that these compounds do not contain nitrogen atoms, or if they do contain nitrogen atoms, their concentrations are low, so they did not achieve a biodegradation promotion effect. In particular, N,N'-ethylenebisoleamide and starch, which are said to promote the biodegradability of resins in compost, were actually reduced in seawater. In particular, it was found that the biodegradable resin composition obtained by kneading resin with nitrogen compounds (I) and (II) had a significantly improved biodegradability of 3 to 5 times, as shown in Examples 14 and 15.

[0117] <Comparative Example 9> PLA was crushed to a particle size (sieving method) of 250 μm or less to obtain a crushed resin. The crushed resin was mixed with tetramethylenediamine dihydrochloride, with 10 parts by weight of tetramethylenediamine dihydrochloride per 100 parts by weight of crushed resin, to obtain a total of 30 mg. The biodegradability of the resulting resin composition was measured in the same manner as in Example 1. As a result, the biodegradability (pressure change) of the resin composition was found to have decreased only by the amount of the added tetramethylenediamine dihydrochloride.

Claims

1. A biodegradable resin composition comprising a polyester resin and one or more compounds selected from nitrogen compounds represented by the following general formula (II) and salts thereof (excluding (RS)-1-methyl-2-nitro-3-[(3-tetrahydrofuryl)methyl]guanidine), wherein the polyester resin is a resin having a dicarboxylic acid unit and a diol unit, and has three or more types of structural units, including at least one of a succinic acid unit and a sebacic acid unit; the nitrogen compound is a straight-chain aliphatic hydrocarbon (excluding "amino acids") containing two or more amino groups and two or more primary amino groups in the molecule; the content of the compound is 0.1% by weight or more and 70% by weight or less; the nitrogen atom concentration in the compound is 6% by weight or more and 40% by weight or less; and the molecular weight of the compound is 90 or more and less than 10,000. 【Chemical 1】 (In the formula, R, R', and R'' each independently represent a hydrogen atom or a monovalent aliphatic organic group, and the aliphatic organic group may have substituents that do not mutually form a ring structure.)

2. 2. The biodegradable resin composition according to claim 1, wherein the concentration of nitrogen atoms derived from the compound contained in the resin composition is 50 ppm by weight or more.

3. 3. The biodegradable resin composition according to claim 1, wherein the monovalent aliphatic organic group which may have a substituent is a monovalent chain aliphatic organic group having 1 to 20 carbon atoms which may have a substituent, the main chain of the aliphatic organic group may contain an element of Groups 15 to 17, and the aliphatic organic group may contain one or more elements selected from the group consisting of a nitrogen atom, a sulfur atom, and a phosphorus atom.

4. 4. The biodegradable resin composition according to claim 1, wherein the compound is at least one selected from the group consisting of spermine, tetramethylenediamine, spermidine, and hydrochlorides thereof.

5. The biodegradable resin composition according to any one of claims 1 to 4, wherein the acid value of the polyester resin is 19 eq / t or more and 250 eq / t or less.

6. The biodegradable resin composition according to any one of claims 1 to 5, wherein the polyester resin is an aliphatic polyester resin or an aliphatic-aromatic polyester resin.

7. The biodegradable resin composition according to any one of claims 1 to 6, wherein the polyester resin has, as a diol unit, one or more selected from the group consisting of 1,4-butanediol, 1,3-propanediol, and ethylene glycol.

8. The biodegradable resin composition according to any one of claims 1 to 7, wherein the polyester resin has a dicarboxylic acid having 2 to 24 carbon atoms as a dicarboxylic acid unit.

9. The biodegradable resin composition according to any one of claims 1 to 8, wherein the polyester resin is at least one selected from the group consisting of PBSA (polybutylene succinate adipate), PBSSe (polybutylene succinate sebacate), PBS (polybutylene succinate), and PBSeT (polybutylene sebacate terephthalate).

10. A molded article comprising the biodegradable resin composition according to any one of claims 1 to 9.

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