Masterbatch, biodegradable resin composition, molded body, and film

Abstract

The present invention provides a masterbatch comprising: a thermoplastic resin and a polyphenol compound containing, in one molecule, 4 to 50 structures in each of which one benzene ring has 1 to 5 phenolic hydroxyl groups bonded thereto.

Description

Masterbatch, biodegradable resin composition, molded article and film

[0001] The present invention relates to a masterbatch, a biodegradable resin composition, a molded article, and a film.

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

[0003] Conventionally, known biodegradable plastics (biodegradable resins) include aliphatic polyesters such as polybutylene terephthalate / adipate (hereinafter abbreviated as PBAT), polylactic acid (hereinafter abbreviated as PLA), polybutylene succinate (hereinafter abbreviated as PBS) and polybutylene succinate / adipate (hereinafter abbreviated as PBSA), and polyhydroxyalkanoates (hereinafter abbreviated as PHA). Further PHAs include poly(3-hydroxybutyrate) (hereinafter abbreviated as PHB), poly(3-hydroxybutyrate / 3-hydroxyvalerate) (hereinafter abbreviated as PHBV), poly(3-hydroxybutyrate / 3-hydroxyhexanoate) (hereinafter abbreviated as PHBH), and poly(3-hydroxybutyrate / 4-hydroxybutyrate).

[0004] These resins not only differ in the rate of biodegradation and the conditions under which they can be biodegraded individually, but also in mechanical properties such as tensile elongation at break and flexural modulus. Therefore, they are generally used in combination with other resins or mixed with other secondary materials and additives depending on the application and location of use.

[0005] Biodegradable resin products are completely biodegradable in nature and in composting equipment. However, they must maintain their usability (e.g., mechanical strength) during use. Therefore, there is a need for technology to control the biodegradation rate depending on the location, duration, and purpose of use. In particular, in agricultural, fishery, civil engineering, and other outdoor applications, the use environments are diverse. In these applications, depending on the use environment, the biodegradation of biodegradable resins may proceed too quickly, preventing them from fully achieving their intended purpose. Therefore, there has been a need for technology to slow the biodegradation rate compared to that of conventional biodegradable resins.

[0006] Patent Document 1 discloses a biodegradable agricultural plastic sheet entirely made of biodegradable plastic, with the biodegradation rate at both widthwise edges of the sheet being slower than at the center. Patent Document 2 discloses an agricultural film having a slow biodegradation rate achieved by partially thickening the film, partially coating the film with a non-biodegradable or slow-biodegradable resin, partially bonding, fusing, two-color molding, or co-extrusion molding the non-biodegradable or slow-biodegradable resin, or partially coating or adding a bactericide or antifungal agent. Patent Document 3 discloses a biodegradable resin composition having an adjusted decomposition rate, including an aliphatic polyester, starch, and an aliphatic aromatic polyester. Patent Document 4 discloses a biodegradable resin composition having an adjusted biodegradation rate due to the inclusion of an inorganic antibacterial agent. Patent Document 5 discloses a biodegradable resin composition having an adjusted biodegradation rate due to the inclusion of a naturally derived organic antibacterial agent.

[0007] Japanese Patent Laid-Open No. 9-107808 Japanese Patent Laid-Open No. 2001-17008 Japanese Patent Laid-Open No. 2008-13602 Japanese Patent Laid-Open No. 5-117507 Japanese Patent Laid-Open No. 2001-323177

[0008] According to the conventional technology of partially molding a molded body to make it thicker (Patent Documents 1 and 2), it is possible to maintain the required strength for a certain period of time, but compared to a molded body of the original thickness, physical properties such as flexibility change and the weight also increases, so there are concerns that the original performance cannot be maintained and costs will increase.

[0009] According to the technique of combining with a resin that is slowly biodegradable, as in Patent Document 3, it is possible to delay the biodegradation compared to the original biodegradable resin, but there is a risk that the mechanical properties may vary significantly because the resin is combined with a resin that has different physical properties such as flexibility.

[0010] As in Patent Document 4, the technology of compounding a bactericide or antibacterial agent makes it possible to adjust the biodegradation rate without significantly changing the physical properties. However, these bactericides and antibacterial agents release compounds that do not naturally occur in nature and heavy metals into the environment, and therefore, even after the biodegradable resin has biodegraded, these compounds remain in the soil and may have a negative impact on ecosystems, agricultural products, etc.

[0011] As in Patent Document 5, the incorporation of naturally derived antibacterial agents can adjust the biodegradation rate and minimize adverse effects on the ecosystem. However, the chitosan used in the examples does not melt at the normal melt-mixing temperature of biodegradable resins, nor is it compatible with biodegradable resins, so it remains in the composition as a particulate solid. This can lead to problems such as poor molding, particularly when molded into films or fibers, and poor texture and appearance. Furthermore, adding more than 5% by weight of chitosan, as in the examples, is not recommended because it may alter flexibility and fluidity.

[0012] One aspect of the present invention has been made in view of the above background, and aims to provide a biodegradable resin composition and a molded article thereof that are ultimately biodegradable, without significantly changing the mechanical properties and other physical properties of the biodegradable resin itself, and that adjust the biodegradation rate so that the biodegradation is delayed. Another aspect of the present invention is to provide a masterbatch that, when used together with a biodegradable resin composition, is ultimately biodegradable, without significantly changing the mechanical properties and other physical properties of the biodegradable resin itself, and that adjusts the biodegradation rate so that the biodegradation is delayed.

[0013] As a result of extensive research to solve the above problems, the inventors discovered that by blending a polyphenol compound having a specific structure with a biodegradable resin, the biodegradation rate can be adjusted so that biodegradation is delayed, leading to the present invention.

[0014] That is, the gist of the present invention resides in the following [1] to

[34] . [1] A masterbatch comprising a polyphenol compound containing, per molecule, 4 to 50 structures in which 1 to 5 phenolic hydroxyl groups are bonded to one benzene ring, and a thermoplastic resin. [2] The masterbatch according to [1], in which the polyphenol compound is contained in an amount of 0.1 parts by mass or more and 400 parts by mass or less per 100 parts by mass of the thermoplastic resin. [3] The masterbatch according to [1] or [2], in which the polyphenol compound is contained in an amount of 5 parts by mass or more and 400 parts by mass or less per 100 parts by mass of the thermoplastic resin. [4] The masterbatch according to any of [1] to [3], in which the polyphenol compound is contained in an amount of more than 10 parts by mass and 400 parts by mass or less per 100 parts by mass of the thermoplastic resin. [5] The masterbatch according to any of [1] to [4], in which the polyphenol compound has a molecular weight of 500 or more. [6] The masterbatch according to any one of [1] to [5], wherein the polyphenol compound is a polyphenol compound containing 4 to 50 structures in one molecule, each structure having 2 to 3 phenolic hydroxyl groups bonded to one benzene ring. [7] The masterbatch according to any one of [1] to [6], wherein the thermoplastic resin is a biodegradable resin. [8] The masterbatch according to [7], wherein the biodegradable resin comprises one or more biodegradable polyester resins selected from the group consisting of aliphatic polyester resins and aliphatic-aromatic polyester resins. [9] The masterbatch according to [7], wherein the biodegradable resin comprises one or more biodegradable polyester resins selected from the group consisting of aliphatic polyester resins whose main structural units are structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid, and aliphatic-aromatic polyester resins.

[10] The masterbatch according to any one of [1] to [9], wherein the polyphenol compound is tannin.

[11] The masterbatch according to

[10] , wherein the tannin is a hydrolyzable tannin.

[12] The masterbatch according to

[11] , wherein the hydrolyzable tannin is tannic acid.

[13] Use of the masterbatch according to any one of [1] to

[12] as a biodegradation retarder for delaying the biodegradation of a biodegradable resin.

[14] A method for producing a molded article, comprising a step of mixing the masterbatch according to any one of [1] to

[12] with a biodegradable resin.

[15] A biodegradable resin composition comprising one or more biodegradable resin components (T) selected from the group consisting of aliphatic polyester resins, polyhydroxyalkanoates, and aliphatic-aromatic polyester resins, whose main structural units are structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid, and a polyphenol compound containing 4 to 50 structures in one molecule, each structure having 1 to 5 phenolic hydroxyl groups bonded to one benzene ring, wherein the content of the biodegradable resin component (T) in the biodegradable resin composition is more than 20% by mass and not more than 99.999% by mass, and the polyphenol compound is contained in a ratio of 0.001 to 10 parts by mass per 100 parts by mass of the biodegradable resin component (T).

[16] The biodegradable resin composition according to

[15] , wherein the molecular weight of the polyphenol compound is 500 or more.

[17] The biodegradable resin composition according to

[15] or

[16] , wherein the polyphenol compound is a polyphenol compound containing 4 to 50 structures in one molecule, each structure having 2 to 3 phenolic hydroxyl groups bonded to one benzene ring.

[18] The biodegradable resin composition according to any one of

[15] to

[17] , wherein the polyphenol compound is a tannin.

[19] The biodegradable resin composition according to

[18] , wherein the tannin is a hydrolyzable tannin.

[20] The biodegradable resin composition according to

[19] , wherein the hydrolyzable tannin is tannic acid.

[21] The biodegradable resin composition according to any one of

[15] to

[20] , wherein the biodegradable resin component (T) comprises an aliphatic polyester resin having, as main structural units, structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid.

[22] The biodegradable resin composition according to any one of

[15] to

[21] , wherein the biodegradable resin component (T) comprises a polyhydroxyalkanoate.

[23] The biodegradable resin composition according to any one of

[15] to

[22] , wherein the biodegradable resin component (T) comprises an aliphatic-aromatic polyester resin.

[24] A molded article obtained by molding the biodegradable resin composition according to any one of

[15] to

[23] .

[25] The molded article according to

[24] , which is an agricultural and forestry material, a fishery material, or a civil engineering material.

[26] A film comprising one or more biodegradable resin components (T) selected from the group consisting of aliphatic polyester resins, polyhydroxyalkanoates, and aliphatic-aromatic polyester resins, whose main structural units are structural units derived from aliphatic diols and structural units derived from aliphatic dicarboxylic acids, and a polyphenol compound containing 4 to 50 structures in one molecule, each structure having 1 to 5 phenolic hydroxyl groups bonded to one benzene ring.

[27] The film according to

[26] , wherein the molecular weight of the polyphenol compound is 500 or more.

[28] The film according to

[26] or

[27] , wherein the polyphenol compound is a polyphenol compound containing 4 to 50 structures in one molecule, each structure having 2 to 3 phenolic hydroxyl groups bonded to one benzene ring.

[29] The film according to any one of

[26] to

[28] , wherein the polyphenol compound is tannin.

[30] The film according to

[29] , wherein the tannin is hydrolyzable tannin.

[31] The film according to

[30] , wherein the hydrolyzable tannin is tannic acid.

[32] The film according to any one of

[26] to

[31] , wherein the biodegradable resin component (T) comprises an aliphatic polyester resin having as main structural units structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid.

[33] The film according to any one of

[26] to

[32] , wherein the biodegradable resin component (T) comprises a polyhydroxyalkanoate.

[34] The film according to any one of

[26] to

[33] , wherein the biodegradable resin component (T) comprises an aliphatic-aromatic polyester resin.

[35] The film according to any one of

[26] to

[34] , wherein the film is an agricultural and forestry material, a fishery material, or a civil engineering material.

[0015] According to one aspect of the present invention, there are provided a biodegradable resin composition and a molded article thereof, which can adjust the biodegradation rate so that biodegradation is delayed without significantly changing the physical properties, such as the mechanical properties, of the biodegradable resin itself, and which ultimately biodegrade. Also, according to another aspect of the present invention, there is provided a masterbatch, which, when used together with a biodegradable resin composition, can adjust the biodegradation rate so that biodegradation is delayed without significantly changing the physical properties, such as the mechanical properties, of the biodegradable resin itself, and which ultimately biodegrades.

[0016] Graph showing the relationship between the number of days elapsed and weight retention in the home composting biodegradability test carried out in the examples. Graph showing the relationship between the number of days elapsed and weight retention in the home composting biodegradability test carried out in the examples. Graph showing the relationship between the number of days elapsed and weight retention in the home composting biodegradability test carried out in the examples. Graph showing the relationship between the number of days elapsed and weight retention in the home composting biodegradability test carried out in the examples. Graph showing the relationship between the number of days elapsed and weight retention in the home composting biodegradability test carried out in the examples. Graph showing the relationship between the number of days elapsed and weight retention in the 40°C biodegradability test carried out in the examples. Graph showing the relationship between the number of days elapsed and weight retention in the 40°C biodegradability test carried out in the examples.

[0017] The following describes embodiments of the present invention in detail. The present invention is not limited to the following description and can be modified as desired without departing from the spirit and scope of the present invention. In this specification, when a numerical value or physical property value is enclosed before and after the prefix "-", the values ​​before and after the prefix are included. Furthermore, when a numerical range expressed as "A to B" or "A or greater but B or less" is described in stages (e.g., in order of preference), the upper and lower limits of each numerical range can be arbitrarily combined. While the following describes embodiments of the present specification in detail, the configurations and their combinations in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the present specification. Furthermore, although multiple embodiments are described in this specification, various conditions in each embodiment can be applied to each other to the extent applicable. Furthermore, the expression "A or B" in this specification can be interpreted as "at least one selected from the group consisting of A and B."

[0018] <Polyphenol Compound> The polyphenol compound contained in the biodegradable resin composition, masterbatch, etc. according to one embodiment of the present invention is characterized by containing 4 to 50 structures in one molecule, each structure having 1 to 5 phenolic hydroxyl groups bonded to one benzene ring. Polyphenol compounds with such structural characteristics have many sites in one molecule that associate with proteins due to CH-π interactions, π-π interactions, and hydrophobic interactions of the benzene ring, and hydrogen bonds of the phenolic hydroxyl groups, and therefore have the effect of binding to proteins and causing their aggregation. Note that one type of polyphenol compound may be used alone, or two or more types may be used in combination.

[0019] Biodegradable resins are completely biodegraded when the polymer chains are cleaved by the action of degradative enzymes secreted by microorganisms such as bacteria and fungi in the environment, and the resulting low-molecular-weight substances are then absorbed and metabolized by the microorganisms. The polyphenol compounds form bonds with enzymes, which are a type of protein, and are thought to inhibit the enzyme's function, thereby delaying biodegradation.

[0020] The molecular weight of the polyphenol compound is preferably 500 or more. When the lower limit of the molecular weight is within this range, the binding strength with proteins is strong, and the biodegradation retarding effect can be effectively exerted. The upper limit of the molecular weight is not particularly limited, but is preferably 10,000 or less, and may be 5,000 or less, 4,000 or less, or 3,000 or less. When the upper limit of the molecular weight is within this range, the polyphenol compound is easily dispersed uniformly in the biodegradable resin, and the biodegradation retarding effect can be effectively exerted. Note that when there is variation in molecular weight and the above range is applied, it is sufficient to include a component whose molecular weight is within the above range.

[0021] The polyphenol compound preferably contains 4 to 50 structures in one molecule, each structure having two or three phenolic hydroxyl groups bonded to one benzene ring. Having two or more phenolic hydroxyl groups bonded to one benzene ring strengthens the binding strength with proteins, enabling effective biodegradation retardation. On the other hand, having three or fewer phenolic hydroxyl groups bonded to one benzene ring provides stability against heat and oxygen, suppresses deterioration during kneading and molding, and enables long-term biodegradation retardation.

[0022] [Tannin] Tannin can be suitably used as the polyphenol compound. Tannin is generally defined as a compound called polyphenol contained in plants that "forms sparingly soluble complexes with proteins, basic substances, etc." and is a substance widely contained in terrestrial plants. Since tannin is a substance widely contained in terrestrial plants, microorganisms containing enzymes such as tannase that decompose tannin are also widely present in the environment. Therefore, after temporarily inhibiting the biodegradation of a biodegradable resin, it is thought that tannins will eventually be completely biodegraded in the environment together with the biodegradable resin, and are particularly preferred because they have little adverse impact on the ecosystem.

[0023] Tannins are natural products with complex compositions, and it is difficult to uniquely identify their molecular structures, but they are broadly classified into hydrolyzable tannins and condensed tannins based on their structural characteristics. When the masterbatch, biodegradable resin composition, etc. according to this embodiment contains tannin, there are no particular limitations on the substance as long as it has the properties of tannin, but hydrolyzable tannin is preferred.

[0024] Hydrolyzable tannins have a structure consisting of aliphatic polyhydric alcohols such as glucose, with a large number (typically 3 to 12) of aromatic carboxylic acids with phenolic hydroxyl groups, such as gallic acid, bonded via ester bonds. The biodegradable resins suitable for use in this embodiment, such as aliphatic polyesters, aliphatic-aromatic polyesters, and polyhydroxyalkanoates, also contain a large number of ester bonds, making them highly compatible and forming a homogeneously mixed composition. This makes them resistant to cutting and tearing, particularly when molded into fibers or films, and facilitates the production of molded articles with excellent appearance and feel. Representative examples of hydrolyzable tannins include tannins extracted from Chinese gallnuts (galls formed on Rhus chinensis) and gall nuts (galls formed on plants in the Fagaceae family). These tannins, also known as "tannic acid," are particularly preferred due to their stable quality and ease of industrial availability. [Nishioka, Kazuo. Recent Research on Tannins.] According to [Yakugaku Zasshi, Vol. 103, No. 2, pp. 125-142 (1983)], tannic acid obtained from Chinese gallnut has an average of 8.3 gallate ester groups per molecule and an average molecular weight of 1,434, while tannic acid obtained from gallnut has an average of 5.6 gallate ester groups per molecule and an average molecular weight of 1,032.

[0025] Condensed tannins have a structure in which a large number (typically several to several tens) of flavan-3-ol compounds such as catechin are bonded via C-C bonds. Since the main chain is long and connected via C-C bonds and contains a larger amount of high molecular weight components than hydrolyzable tannins, they may not be sufficiently compatible with biodegradable resins. Condensed tannins, for example, extracted from trees such as mimosa (also known as wattle) and quebracho, are commercially available and can be used. For example, mimosa tannins obtained by extraction from mimosa are described in the literature [Liu, J.; Ando, ​​R.; Shimizu, K. et al. Steroid 5α-reductase inhibitory activity of condensed tannins from woody plants. J. Wood Sci. 54, 68-75 (2008)], the number average molecular weight is approximately 1300 to 2500, and the main constituent unit is prorobinetinidine with a formula weight of 288. Prorobinetinidine contains one benzene ring unit having one bonded phenolic hydroxyl group and one benzene ring unit having three bonded phenolic hydroxyl groups, and therefore it is estimated that one molecule contains an average of about 9 to 17 structures having one to five bonded phenolic hydroxyl groups to one benzene ring, and an average of about 5 to 9 structures having two to three bonded phenolic hydroxyl groups to one benzene ring.

[0026] <Biodegradable Resin Composition> A biodegradable resin composition according to one embodiment of the present invention (hereinafter also referred to simply as the "biodegradable resin composition") comprises, as essential components, an aliphatic polyester resin (A) (hereinafter simply referred to as the "aliphatic polyester resin (A)") having, as its main structural units, structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid; one or more biodegradable resin components (T) selected from the group consisting of an aliphatic-aromatic polyester resin (B) and a polyhydroxyalkanoate (D); and the polyphenol compound described above. Herein, the term "main structural unit" refers to a structural unit that is contained in the target resin at 80 mol% or more, and may be contained at 90 mol% or more. It may also be 100 mol% when no structural units other than the main structural unit are contained. For example, the content of the main structural unit in the expression "contains structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid as main structural units" refers to the total content of structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid.

[0027] The content of the biodegradable resin component (T) in the biodegradable resin composition is greater than 20% by mass and less than 99.999% by mass. Because enzymes that hydrolyze the biodegradable resin component (T) in a natural environment are susceptible to inhibition by the polyphenol compounds, a biodegradation retardation effect is exhibited when the content of the biodegradable resin component (T) exceeds the lower limit of this range. Furthermore, since the biodegradable resin component (T) has excellent compatibility with polyphenol compounds, a composition with excellent mechanical strength and appearance can be obtained. For the same reasons, the content of the biodegradable resin component (T) is preferably greater than 30% by mass, more preferably greater than 40% by mass, particularly preferably greater than 50% by mass, and most preferably greater than 60% by mass. The upper limit is not particularly limited, but may be 99.999% by mass or less, or may be 99% by mass or less, 95% by mass or less, 90% by mass or less, or 80% by mass or less.

[0028] The content ratio of the polyphenol compound contained in the biodegradable resin composition is 0.001 parts by mass or more and 10 parts by mass or less, preferably 0.01 parts by mass or more and 7 parts by mass or less, more preferably 0.1 parts by mass or more and 5 parts by mass or less, particularly preferably 0.3 parts by mass or more and 4 parts by mass or less, and most preferably 0.5 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the biodegradable resin component (T). When this ratio is above the lower limit of this range, the biodegradation retardation effect can be effectively exerted. Furthermore, when this ratio is below the upper limit of this range, deterioration of mechanical properties and poor appearance can be suppressed. Particularly preferably, the content ratio of the polyphenol compound having a molecular weight of 500 or more and 10,000 or less in the biodegradable resin composition is 0.001 parts by mass or more and 10 parts by mass or less, preferably 0.01 parts by mass or more and 7 parts by mass or less, more preferably 0.1 parts by mass or more and 5 parts by mass or less, particularly preferably 0.3 parts by mass or more and 4 parts by mass or less, and most preferably 0.5 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the biodegradable resin component (T).

[0029] The biodegradable resin composition may contain a biodegradable resin other than the biodegradable resin component (T) as long as the above conditions are satisfied. Examples of biodegradable resins other than the biodegradable resin component (T) include polylactic acid, polyglycolic acid, polycaprolactone, polyvinyl alcohol or a copolymer thereof, cellulose or an esterified derivative thereof, and starch or a derivative thereof. The content of the biodegradable resin other than the biodegradable resin component (T) in the biodegradable resin composition is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and most preferably 20% by mass or less.

[0030] [Biodegradable Resin] Each biodegradable resin will be described below. The aliphatic polyester resin (A), the aliphatic-aromatic polyester resin (B), and the polyhydroxyalkanoate (D) are each polymers having repeating units, and each repeating unit 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," a repeating unit derived from an aromatic dicarboxylic acid is also referred to as an "aromatic dicarboxylic acid unit," and a repeating unit derived from an aliphatic oxycarboxylic acid is also referred to as an "aliphatic oxycarboxylic acid unit." The biodegradable resins may be used alone or in combination of two or more.

[0031] [Aliphatic polyester resin (A)] The biodegradable resin component (T) preferably contains an aliphatic polyester resin (A) from the viewpoint of providing appropriate rigidity and opening properties during inflation molding. The aliphatic polyester resin (A) preferably contains succinic acid units, and the succinic acid unit content of all dicarboxylic acid units (hereinafter also referred to simply as "total dicarboxylic acid units") contained in all aliphatic polyester resins (A) contained in the biodegradable resin composition is more preferably 5 mol% or more and 100 mol% or less. The aliphatic polyester resin (A) may be a mixture of aliphatic polyester resins with different amounts of succinic acid units. For example, an aliphatic polyester resin containing no aliphatic dicarboxylic acid units other than succinic acid (containing only succinic acid units as aliphatic dicarboxylic acid units) may be blended with an aliphatic polyester resin containing aliphatic dicarboxylic acid units other than succinic acid, and the amount of succinic acid units in the aliphatic polyester resin (A) may be adjusted to fall within the above-mentioned preferred range.

[0032] More specifically, the aliphatic polyester resin (A) is a polyester resin containing an aliphatic diol unit represented by the following formula (1) and an aliphatic dicarboxylic acid unit represented by the following formula (2): １ -O- (1) -OC-R ２ -CO- (2)

[0033] In formula (1), R １ represents a divalent aliphatic hydrocarbon group. ２ represents a divalent aliphatic hydrocarbon group. The aliphatic diol unit and the aliphatic dicarboxylic acid unit represented by the above formulas (1) and (2) may be derived from a compound derived from petroleum or a compound derived from a plant raw material, but are preferably derived from a compound derived from a plant raw material.

[0034] When the aliphatic polyester-based resin (A) is a copolymer, the aliphatic polyester-based resin (A) may contain two or more types of aliphatic diol units represented by formula (1), and the aliphatic polyester-based resin (A) may contain two or more types of aliphatic dicarboxylic acid units represented by formula (2).

[0035] As mentioned above, the aliphatic dicarboxylic acid unit represented by formula (2) preferably contains a succinic acid unit, and the succinic acid unit is preferably contained in a content of 5 mol% to 100 mol% based on 100 mol% of all dicarboxylic acid units. By setting the content of succinic acid structural units in the aliphatic polyester-based resin (A) within the above-mentioned range, it is possible to obtain a biodegradable resin composition that has improved moldability and excellent heat resistance and biodegradability. For the same reason, the content of succinic acid units in the aliphatic polyester-based resin (A) is preferably 10 mol% or more, more preferably 50 mol% or more, even more preferably 64 mol% or more, and particularly preferably 68 mol% or more based on 100 mol% of all dicarboxylic acid units.

[0036] The aliphatic diol that provides the diol unit represented by formula (1) is not particularly limited, but from the viewpoint of moldability and mechanical strength, an aliphatic diol having from 2 to 10 carbon atoms is preferred, and an aliphatic diol having from 4 to 6 carbon atoms is particularly preferred. Examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol, and of these, 1,4-butanediol is particularly preferred. It is also possible to use two or more types of the above aliphatic diols.

[0037] The aliphatic dicarboxylic acid component that provides the aliphatic dicarboxylic acid unit represented by formula (2) is not particularly limited, but is preferably an aliphatic dicarboxylic acid having from 2 to 40 carbon atoms or a derivative thereof such as an alkyl ester, and particularly preferably an aliphatic dicarboxylic acid having from 4 to 12 carbon atoms or a derivative thereof such as an alkyl ester. Examples of aliphatic dicarboxylic acids having from 2 to 40 carbon atoms other than succinic acid or derivatives thereof such as an alkyl ester include adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, etc., or derivatives thereof such as alkyl esters, and among these, adipic acid or sebacic acid is preferred. Note that two or more types of the aliphatic dicarboxylic acid component can be used, and in this case, a combination of succinic acid and adipic acid, or a combination of succinic acid and sebacic acid is preferred.

[0038] The aliphatic polyester resin (A) may have a repeating unit (aliphatic oxycarboxylic acid unit) derived from an aliphatic oxycarboxylic acid. Specific examples of the aliphatic oxycarboxylic acid component that provides the aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, 6-hydroxycaproic acid, and the like, as well as derivatives thereof, such as lower alkyl esters or intramolecular esters. When optical isomers of these are present, they may be in the D-form, L-form, or racemic form, and may be in the form of a solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid, or derivatives thereof, are particularly preferred. These aliphatic oxycarboxylic acids may be used alone or as a mixture of two or more.

[0039] When the aliphatic polyester resin (A) contains these aliphatic oxycarboxylic acid units, the content thereof is preferably 20 mol % or less, more preferably 10 mol % or less, even more preferably 5 mol % or less, and most preferably 0 mol % (not contained, i.e., below the detection limit), from the viewpoint of moldability, assuming that all structural units constituting the aliphatic polyester resin (A) are 100 mol %.

[0040] The melt viscosity of the aliphatic polyester resin (A) may be increased by copolymerizing a trifunctional or higher aliphatic polyhydric alcohol, a trifunctional or higher aliphatic polycarboxylic acid or its acid anhydride, or a trifunctional or higher aliphatic polyoxycarboxylic acid component.

[0041] Specific examples of trifunctional aliphatic polyhydric alcohols include trimethylolpropane and glycerin, and specific examples of tetrafunctional aliphatic polyhydric alcohols include pentaerythritol. These may be used alone or in combination of two or more. Specific examples of trifunctional aliphatic polycarboxylic acids or acid anhydrides thereof include propanetricarboxylic acid or its acid anhydride, and specific examples of tetrafunctional polycarboxylic acids or its acid anhydrides include cyclopentanetetracarboxylic acid or its acid anhydride. These may be used alone or in combination of two or more.

[0042] Trifunctional aliphatic oxycarboxylic acids are divided 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, and either type can be used, but from the viewpoints of moldability, mechanical strength, and the appearance of molded products, (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, such as malic acid, is preferred, more specifically, malic acid is preferably used. Tetrafunctional aliphatic oxycarboxylic acid components are divided into (i) a type having three carboxyl groups and one hydroxyl group in the same molecule, (ii) a type having two carboxyl groups and two hydroxyl groups in the same molecule, and (iii) a type having three hydroxyl groups and one carboxyl group in the same molecule, and either type can be used, but those having multiple carboxyl groups are preferred, more specifically, citric acid, tartaric acid, etc. These may be used alone or in combination of two or more.

[0043] When the aliphatic polyester resin (A) contains such a structural unit derived from a trifunctional or higher functional component, the content thereof, relative to all structural units constituting the aliphatic polyester resin (A) as 100 mol %, is such that the lower limit is usually 0 mol % or more, preferably 0.01 mol % or more, and the upper limit is usually 5 mol % or less, preferably 2.5 mol % or less.

[0044] The aliphatic polyester resin (A) can be produced by a known method for producing polyesters. The polycondensation reaction can be carried out under any 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.

[0045] When a diol component forming a diol unit and a dicarboxylic acid component forming a dicarboxylic acid unit are reacted during the production of the aliphatic polyester resin (A), the amounts of the diol component and the dicarboxylic acid component used are set so that the aliphatic polyester resin (A) produced has the desired composition. Usually, the diol component and the dicarboxylic acid component react in substantially equimolar amounts, but the diol component is usually used in a 1 to 20 mol % excess over the dicarboxylic acid component because it is distilled off during the esterification reaction.

[0046] When the aliphatic polyester resin (A) contains component units (optional component units) other than the essential component units such as aliphatic oxycarboxylic acid units and polyfunctional component units, the corresponding compounds (monomers and oligomers) are reacted so that the aliphatic oxycarboxylic acid units and polyfunctional component units also have the desired compositions. In this case, there are no limitations on the timing and method of introducing the optional components into the reaction system, and they are arbitrary as long as the aliphatic polyester resin (A) can be produced.

[0047] For example, the timing and method of introducing the aliphatic hydroxycarboxylic acid into the reaction system are not particularly limited as long as it is before the polycondensation reaction between the diol component and the dicarboxylic acid component. Examples include (1) a method in which the catalyst is dissolved in an aliphatic hydroxycarboxylic acid solution in advance and mixed, and (2) a method in which the catalyst is introduced into the reaction system and mixed at the same time when the raw materials are charged.

[0048] The timing of introducing the compound that forms the polyfunctional component unit may be such that it is charged simultaneously with other monomers or oligomers at the initial stage of polymerization, or it may be charged after the transesterification reaction and before the start of decompression. However, charging it simultaneously with other monomers or oligomers is preferred from the viewpoint of simplifying the process.

[0049] The aliphatic polyester resin (A) is usually produced in the presence of a catalyst. As the catalyst, any catalyst that can be used in the production of known polyester resins can be selected as long as it does not significantly impair the effects of the present invention. Examples of the catalyst include metal compounds such as germanium, titanium, zirconium, hafnium, antimony, tin, magnesium, calcium, and zinc. Among them, germanium compounds and titanium compounds are preferred.

[0050] 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, and tetrabutoxygermanium are preferred in terms of price and availability, with germanium oxide being particularly preferred.

[0051] Examples of titanium compounds that can be used as catalysts include organic titanium compounds such as tetraalkoxytitanium compounds such as tetrapropyl titanate, tetrabutyl titanate, and tetraphenyl titanate. Among these, tetrapropyl titanate and tetrabutyl titanate are preferred in terms of price and availability.

[0052] 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.

[0053] The amount of catalyst used is arbitrary as long as it does not significantly impair the effects of the present invention, but is usually 0.0005% by mass or more, more preferably 0.001% by mass or more, and usually 3% by mass or less, preferably 1.5% by mass or less, based on 100% by mass of the monomer used. If the amount is below the lower limit of this range, the effect of the catalyst may not be exhibited, while if the amount is above the upper limit, the production cost may increase, the resulting polymer may be significantly discolored, or the hydrolysis resistance may be reduced.

[0054] 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 pressure reduction is started. When an aliphatic oxycarboxylic acid unit is introduced, it is preferably introduced simultaneously with a monomer or oligomer that forms an aliphatic oxycarboxylic acid unit, such as lactic acid or glycolic acid, when the raw materials are charged, or by dissolving the catalyst in an aqueous aliphatic oxycarboxylic acid solution and introducing it. In particular, the method of dissolving the catalyst in an aqueous aliphatic oxycarboxylic acid solution and introducing it is preferred because it increases the polymerization rate.

[0055] The reaction conditions, such as temperature, time, and pressure, for producing the aliphatic polyester resin (A) may be any as long as they do not significantly impair the effects of the present invention. However, the reaction temperature for the esterification reaction and / or transesterification reaction between the dicarboxylic acid component and the diol component is typically 150°C or higher, preferably 180°C or higher, and typically 260°C or lower, preferably 250°C or lower. The reaction atmosphere is typically an inert atmosphere such as nitrogen or argon. The reaction pressure is typically between atmospheric pressure and 10 kPa, with atmospheric pressure being preferred. The reaction time is typically 1 hour or higher, and typically 10 hours or shorter, preferably 6 hours or shorter, more preferably 4 hours or shorter. If the reaction temperature is too high, excessive unsaturated bonds may be produced, resulting in gelation caused by the unsaturated bonds, making it difficult to control the polymerization.

[0056] The polycondensation reaction after the esterification reaction and / or transesterification reaction between the dicarboxylic acid component and the diol component is carried out under a pressure of usually 0.01×10 ３ Pa or more, preferably 0.03 × 10 ３ Pa or more, with an upper limit of 1.4 x 10３ Pa or less, preferably 0.4 × 10 ３ It is desirable to carry out the reaction in an environment under a vacuum of 0.1 Pa or less. The lower limit of the reaction temperature is usually 150°C or higher, preferably 180°C or higher, and the upper limit is usually 260°C or lower, preferably 250°C or lower. The lower limit of the reaction time is usually 2 hours or higher, and the upper limit is usually 15 hours or lower, preferably 10 hours or lower. If the reaction temperature is too high, excessive generation of unsaturated bonds may cause gelation due to the unsaturated bonds, making it difficult to control the polymerization.

[0057] When producing the aliphatic polyester resin (A), a chain extender such as a carbonate compound or a diisocyanate compound can also be used. In this case, the amount of the chain extender is not particularly limited, but the chain extender can be used so that the total ratio of bonds such as carbonate bonds and urethane bonds (bonds formed by the chain extender) contained in the aliphatic polyester resin (A) is usually 10 mol % or less, preferably 5 mol % or less, and more preferably 3 mol % or less, when all structural units constituting the aliphatic polyester resin (A) are taken as 100 mol %. However, if urethane bonds or carbonate bonds exist in the aliphatic polyester resin (A), they may inhibit biodegradability, so the total ratio of one or more bonds selected from the group consisting of urethane bonds and carbonate bonds to 100 mol% of all structural units constituting the aliphatic polyester resin (A) is less than 1 mol%, preferably 0.5 mol% or less, more preferably 0.1 mol% or less, and the urethane bonds are 0.55 mol% or less, preferably 0.3 mol% or less, more preferably 0.12 mol% or less, and even more preferably 0.05 mol% or less. In particular, if the amount of urethane bonds exceeds the upper limit, in the film-forming process, etc., the decomposition of urethane bonds may cause problems such as smoke and odor from the molten film at the die outlet, and may also cause film breakage due to foaming in the molten film, making it impossible to stably mold it. Note that the amount of carbonate bonds and the amount of urethane bonds in the aliphatic polyester resin (A) are １ H-NMR and １３It can be determined by calculation from the results of NMR measurements such as C-NMR. The types of bonds contained in the aliphatic polyester resin (A) and the amount of each bond other than carbonate bonds and urethane bonds can also be determined in a similar manner.

[0058] Specific examples of carbonate compounds as the chain extender include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, dicyclohexyl carbonate, etc. In addition, carbonate compounds composed of the same or different hydroxy compounds derived from hydroxy compounds such as phenols or alcohols can also be used.

[0059] 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.

[0060] Other chain extenders that may be used include dioxazoline, silicate esters, etc. Specific examples of silicate esters include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxysilane.

[0061] High molecular weight polyester resins using these chain extenders (coupling agents) can also be produced using conventional techniques. After polycondensation is complete, the chain extender is added to the reaction system in a homogeneous molten state without a solvent, and reacted with the polyester obtained by polycondensation.

[0062] More specifically, a polyester having substantially hydroxyl terminal groups and a weight-average molecular weight (Mw) of 20,000 or more, preferably 40,000 or more, obtained by catalytically reacting a diol component with a dicarboxylic acid component, can be reacted with the chain extender to obtain a polyester resin with a higher molecular weight. A prepolymer having a weight-average molecular weight of 20,000 or more can be produced by using a small amount of chain extender without the influence of residual catalyst, even under severe conditions such as a molten state, and thus can produce a high-molecular-weight polyester resin without forming a gel during the reaction. The weight-average molecular weight (Mw) of the polyester resin is determined by gel permeation chromatography (GPC) using chloroform as the solvent at 40°C, converted into a monodisperse polystyrene value.

[0063] Therefore, when further increasing the molecular weight of a polyester resin using, for example, the above-mentioned diisocyanate compound as a chain extender, it is preferable to use a prepolymer having a weight-average molecular weight of 20,000 or more, preferably 40,000 or more. If the weight-average molecular weight is less than 20,000, the amount of diisocyanate compound used to increase the molecular weight may increase, resulting in a decrease in heat resistance. Using such a prepolymer, a polyester resin having urethane bonds with a linear structure linked via urethane bonds derived from the diisocyanate compound is produced.

[0064] The pressure during chain extension is usually 0.01 MPa or more and 1 MPa or less, preferably 0.05 MPa or more and 0.5 MPa or less, more preferably 0.07 MPa or more and 0.3 MPa or less, and most preferably normal pressure.

[0065] The lower limit of the reaction temperature during chain extension is usually 100° C. or higher, preferably 150° C. or higher, more preferably 190° C. or higher, and most preferably 200° C. or higher, and the upper limit is usually 250° C. or lower, preferably 240° C. or lower, and more preferably 230° C. or lower. If the reaction temperature is too low, the viscosity will be high, making it difficult to achieve a uniform reaction, and high stirring power will tend to be required. If the reaction temperature is too high, gelation or decomposition of the polyester resin will tend to occur concomitantly.

[0066] The lower limit of the time for chain extension is usually 0.1 minute or more, preferably 1 minute or more, more preferably 5 minutes or more, and the upper limit is usually 5 hours or less, preferably 1 hour or less, more preferably 30 minutes or less, and most preferably 15 minutes or less. If the time for chain extension is too short, the effect of adding the chain extender tends not to be exerted, and if it is too long, gelation or decomposition of the polyester resin tends to occur concomitantly.

[0067] The molecular weight of the aliphatic polyester resin (A) can be measured by gel permeation chromatography (GPC). The weight average molecular weight (Mw) of the aliphatic polyester resin (A) using monodisperse polystyrene as the standard is usually 10,000 or more and 1,000,000 or less, but is preferably 20,000 or more and 500,000 or less, more preferably 50,000 or more and 400,000 or less, because this is advantageous in terms of moldability and mechanical strength.

[0068] The melt flow rate (MFR) of the aliphatic polyester resin (A), as measured at 190°C under a load of 2.16 kg in accordance with JIS K7210 (1999), is usually 0.1 g / 10 min or more and 100 g / 10 min or less, but from the viewpoints of moldability and mechanical strength, it is preferably 50 g / 10 min or less, particularly preferably 40 g / 10 min or less. The MFR of the aliphatic polyester resin (A) can be adjusted by the molecular weight.

[0069] The melting point of the aliphatic polyester resin (A) is preferably 70°C or higher, more preferably 75°C or higher, and is preferably 170°C or lower, more preferably 150°C or lower, and particularly preferably lower than 130°C. When there are multiple melting points, it is preferable that at least one of the melting points is within the above range. Furthermore, the elastic modulus of the aliphatic polyester resin (A) is preferably 180 to 1000 MPa. If the melting point is outside the above range, moldability will be poor, and if the elastic modulus is less than 180 MPa, problems with moldability will likely occur, while if the elastic modulus exceeds 1000 MPa, impact strength will tend to be poor.

[0070] The method for adjusting the melting point and elastic modulus of the aliphatic polyester resin (A) is not particularly limited. For example, the melting point and elastic modulus can be adjusted by selecting the type of copolymerization component of the aliphatic dicarboxylic acid component other than succinic acid, adjusting the copolymerization ratio of each component, or combining these components.

[0071] The aliphatic polyester resin (A) is not limited to one type, and a blend of two or more types of aliphatic polyester resins (A) differing in the type and ratio of constituent units, production method, physical properties, etc. may be used.

[0072] [Aliphatic-aromatic polyester resin (B)] From the viewpoint of providing appropriate tensile strength and tear strength, the biodegradable resin component (T) preferably contains an aliphatic-aromatic polyester resin (B). Examples of the aliphatic-aromatic polyester resin (B) include those in which at least a portion of the repeating units of the above-mentioned aliphatic polyester resin (A) have been replaced with aromatic compound units, preferably polyester resins containing aliphatic diol units, aliphatic dicarboxylic acid units, and aromatic dicarboxylic acid units as main constituent units, in which a portion of the aliphatic dicarboxylic acid units of the above-mentioned aliphatic polyester resin (A) have been replaced with aromatic dicarboxylic acid units.

[0073] Examples of aromatic compound units include aromatic diol units having an aromatic hydrocarbon group which may have a substituent, aromatic dicarboxylic acid units having an aromatic hydrocarbon group which may have a substituent, aromatic dicarboxylic acid units having an aromatic heterocyclic group which may have a substituent, and aromatic oxycarboxylic acid units having an aromatic hydrocarbon group which may have a substituent. The aromatic hydrocarbon group and aromatic heterocyclic group may be monocyclic or may have multiple rings bonded or condensed together. Specific examples of aromatic hydrocarbon groups include a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a dinaphthylene group, and a diphenylene group. Specific examples of aromatic heterocyclic groups include a 2,5-furandiyl group.

[0074] Examples of the substituent that the aromatic hydrocarbon group or aromatic heterocyclic group may have include alkyl groups such as a methyl group, an ethyl group, or a propyl group; alkoxy groups such as a methoxy group or an ethoxy group; acyl groups such as an acetyl group or a propionyl group; a phenyl group, a benzyl group, or a phenoxy group.

[0075] Specific examples of aromatic dicarboxylic acid components that provide aromatic dicarboxylic acid units include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 2,5-furandicarboxylic acid. Among these, terephthalic acid is preferred.

[0076] The aromatic dicarboxylic acid component may be a derivative of an aromatic dicarboxylic acid compound. For example, derivatives of the aromatic dicarboxylic acid components exemplified above are preferred, and among them, lower alkyl esters containing a lower alkyl having 1 to 4 carbon atoms, acid anhydrides, etc. are mentioned. Specific examples of derivatives of aromatic dicarboxylic acid compounds include lower alkyl esters such as methyl esters, ethyl esters, propyl esters, or butyl esters of the aromatic dicarboxylic acid components exemplified above; or cyclic acid anhydrides of the aromatic dicarboxylic acid components exemplified above, such as succinic anhydride; etc. Among them, dimethyl terephthalate is preferred.

[0077] Specific examples of aromatic diol components that provide aromatic diol units include xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, and bis(4-β-hydroxyethoxyphenyl)sulfonic acid. The aromatic diol component may be a derivative of an aromatic diol compound. Alternatively, the aromatic diol component may be a compound having a structure in which a plurality of aliphatic diol compounds and / or aromatic diol compounds are dehydrated and condensed together.

[0078] Specific examples of aromatic oxycarboxylic acid components that provide aromatic oxycarboxylic acid units include p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid. The aromatic oxycarboxylic acid component may be a derivative of an aromatic oxycarboxylic acid compound. Alternatively, it may be a compound (oligomer) having a structure in which a plurality of aliphatic oxycarboxylic acid compounds and / or aromatic oxycarboxylic acid compounds are dehydrated and condensed with each other. That is, an oligomer may be used as a raw material.

[0079] When the aromatic compound component that provides these aromatic compound units has optical isomers, any of the D-isomer, L-isomer, and racemic isomer may be used. Furthermore, the aromatic compound component is not limited to the above examples, as long as it can provide an aromatic compound unit. Furthermore, the aromatic compound component may be used alone, or two or more kinds may be used in any combination and ratio.

[0080] As 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 and 80 mol% or less, based on the total amount of the aliphatic dicarboxylic acid units and the aromatic dicarboxylic acid units (100 mol%). Furthermore, it is preferable to use terephthalic acid or 2,5-furandicarboxylic acid as the aromatic dicarboxylic acid component. In this case, the aliphatic-aromatic polyester resin (B) is preferably a polybutylene terephthalate adipate and / or polybutylene terephthalate succinate resin. Furthermore, polybutylene-2,5-furandicarboxylate resins are also preferred as the aliphatic-aromatic polyester resin (B).

[0081] The aliphatic-aromatic polyester resin (B) can be produced in the same manner as the aliphatic polyester resin (A) described above, using at least an aromatic compound component as a raw material.

[0082] The molecular weight of the aliphatic-aromatic polyester resin (B) can be measured by gel permeation chromatography (GPC). The weight average molecular weight (Mw) of the aliphatic-aromatic polyester resin (B) using monodisperse polystyrene as the standard is usually 10,000 or more and 1,000,000 or less, but is preferably 30,000 or more and 800,000 or less, more preferably 50,000 or more and 600,000 or less, because this is advantageous in terms of moldability and mechanical strength.

[0083] The melt flow rate (MFR) of the aliphatic-aromatic polyester resin (B) is measured at 190°C under a load of 2.16 kg according to JIS K7210 (1999), and is usually 0.1 g / 10 min or more and 100 g / 10 min or less, but from the viewpoints of moldability and mechanical strength, it is preferably 50 g / 10 min or less, particularly preferably 30 g / 10 min or less. The MFR of the aliphatic-aromatic polyester resin (B) can be adjusted by the molecular weight.

[0084] The melting point of the aliphatic-aromatic polyester resin (B) is usually 60°C or higher, preferably 70°C or higher, more preferably 80°C or higher, and preferably 150°C or lower, more preferably 140°C or lower, and particularly preferably 120°C or lower. When there are multiple melting points, it is preferable that at least one melting point is within the above range. In addition, the elastic modulus of the aliphatic-aromatic polyester resin (B) is preferably 180 to 1000 MPa. If the melting point is outside the above range, moldability will be poor, and if the elastic modulus is less than 180 MPa, problems will likely occur in moldability, while if the elastic modulus exceeds 1000 MPa, impact strength will tend to be poor.

[0085] The method for adjusting the melting point and elastic modulus of the aliphatic-aromatic polyester resin (B) is not particularly limited, but for example, they can be adjusted by selecting the type of copolymerization component of the aliphatic dicarboxylic acid component other than the aromatic dicarboxylic acid component, adjusting the copolymerization ratio of each, or combining them.

[0086] The aliphatic-aromatic polyester resin (B) is not limited to one type, and two or more types of aliphatic-aromatic polyester resins (B) differing in the types and ratios of constituent units, production methods, physical properties, etc. can be blended and used.

[0087] [Polyhydroxyalkanoate (D)] The biodegradable resin component (T) preferably contains a polyhydroxyalkanoate (D) from the viewpoint of providing appropriate rigidity and biodegradability. The polyhydroxyalkanoate (hereinafter sometimes referred to as PHA) (D) is an aliphatic polyester containing a repeating unit represented by the following formula (4), and preferably contains a 3-hydroxybutyrate unit (i.e., R ４ is a methyl group) as the main structural unit. ４ -CH ２ —CO— (4) (In the above formula (4), R ４ represents an alkyl group having 1 to 15 carbon atoms.

[0088] From the viewpoints of moldability and thermal stability, the polyhydroxyalkanoate (D) preferably contains 80 mol% or more, and more preferably 85 mol% or more, of 3-hydroxybutyrate units relative to 100 mol% of all structural units constituting the polyhydroxyalkanoate (D). Furthermore, polyhydroxyalkanoates produced by microorganisms are preferred. Specific examples of polyhydroxyalkanoates (D) include poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resins and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) copolymer resins. In particular, from the viewpoints of moldability and the physical properties of the resulting molded articles, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resins, i.e., PHBH, are preferred.

[0089] In the polyhydroxyalkanoate (D), the composition ratio of 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) to the copolymerized comonomer such as 3-hydroxyhexanoate (hereinafter sometimes referred to as 3HH), i.e., the monomer ratio in the copolymer resin, is preferably 3 to 20 mol%, and more preferably 5 to 15 mol%, based on 100 mol% of the total units of 3-hydroxybutyrate units and comonomer units, from the viewpoints of molding processability and molded product quality. If this comonomer ratio is less than 3 mol%, molding may be difficult due to the proximity of the molding temperature and the thermal decomposition temperature. If the comonomer ratio exceeds 20 mol%, the crystallization of the polyhydroxyalkanoate (D) may be slowed, resulting in poor productivity.

[0090] The ratio of each monomer in polyhydroxyalkanoate (D) can be measured by gas chromatography as follows. 2 ml of a sulfuric acid / methanol mixture (15 / 85 (mass ratio)) and 2 ml of chloroform are added to approximately 20 mg of dry PHA, the container is sealed, and heated at 100°C for 140 minutes to obtain the methyl ester of the PHA decomposition product. After cooling, 1.5 g of sodium bicarbonate is added little by little to neutralize the mixture, and the mixture is left to stand until the evolution of carbon dioxide gas stops. 4 ml of diisopropyl ether is added and mixed well, and the monomer unit composition of the PHA decomposition product in the supernatant is analyzed by capillary gas chromatography, whereby the ratio of each monomer in the copolymer resin can be determined.

[0091] The weight-average molecular weight (hereinafter sometimes referred to as Mw) of polyhydroxyalkanoate (D) can be measured by the aforementioned gel permeation chromatography (GPC), and the weight-average molecular weight (Mw) using monodisperse polystyrene as the standard substance is usually 200,000 to 2,500,000, but is preferably 250,000 to 2,000,000, more preferably 300,000 to 1,000,000, because this is advantageous in terms of moldability and mechanical strength. If the weight-average molecular weight is less than 200,000, the mechanical properties may be poor, and if it exceeds 2,500,000, molding processing may be difficult.

[0092] The melt flow rate (MFR) of the polyhydroxyalkanoate (D), as measured at 190°C under a load of 2.16 kg in accordance with JIS K7210 (1999), is preferably 1 g / 10 min or more and 100 g / 10 min or less, but from the viewpoints of moldability and mechanical strength, is more preferably 80 g / 10 min or less, and particularly preferably 50 g / 10 min or less. The MFR of the polyhydroxyalkanoate (D) can be adjusted by the molecular weight.

[0093] The melting point of the polyhydroxyalkanoate (D) is preferably 100° C. or higher, more preferably 120° C. or higher, and preferably 180° C. or lower, more preferably 170° C. or lower, particularly preferably lower than 160° C. When there are multiple melting points, it is preferable that at least one of the melting points is within the above range.

[0094] Polyhydroxyalkanoate (D) can be produced by, for example, a microorganism such as Alcaligenes eutrophus AC32 strain (international deposit under the Budapest Treaty, international depository authority: National Institute of Advanced Industrial Science and Technology International Patent Organism Depositary (6-1 Central, 1-1 Higashi, Tsukuba, Ibaraki Prefecture, Japan), original deposit date: August 12, 1996, transferred on August 7, 1997, deposit number FERM BP-6038 (transferred from original deposit FERM P-15786)) (J. Bacteriol., 179, 4821 (1997)).

[0095] As the polyhydroxyalkanoate (D), commercially available products can also be used. Examples of commercially available polyhydroxyalkanoates (D) containing 3-hydroxybutyrate units and 3-hydroxyhexanoate units as main constituent units include "PHBH X331N," "PHBH X131A," and "PHBH X151A" manufactured by Kaneka Corporation.

[0096] [Other Components] In addition to the above-mentioned components, the biodegradable resin composition may contain components (other components) such as fillers (bulking agents), plasticizers, antistatic agents, antioxidants, light stabilizers, UV 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, or various additives such as slip agents. The biodegradable resin composition may also contain functional additives such as freshness-preserving agents or antibacterial agents as other components.

[0097] These other components can be blended as desired within the range that does not impair the effects of the present invention, and one type may be used alone, or two or more types may be used in combination.

[0098] In order not to impair the physical properties of the biodegradable resin composition, the content of these other components in the biodegradable resin composition is usually preferably such that the total content of the other components is 0.01% by mass or more and 40% by mass or less relative to the total amount of the biodegradable resin composition.

[0099] <Method for producing biodegradable resin composition> The biodegradable resin composition is produced, for example, by kneading the above-mentioned biodegradable resin and a polyphenol compound in a kneader to disperse the polyphenol compound in the biodegradable resin. In addition, other resins and other components used as needed may be mixed in the kneader together with the polyphenol compound and the biodegradable resin.

[0100] This kneading step (kneading step) can be carried out by mixing the polyphenol compound and biodegradable resin with other resins and other components used as needed in a predetermined ratio simultaneously or in any order using a mixer such as a tumbler mixer, V-type blender, Nauta mixer, Banbury mixer, kneading roll, or extruder, and is preferably carried out by further melt-kneading.

[0101] The kneader used in the kneading step 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.

[0102] The temperature during melt-kneading is preferably 70° C. or higher, more preferably 90° C. or higher, particularly preferably 110° C. or higher, and most preferably 130° C. or higher, from the viewpoint of uniformly dispersing the polyphenol compound in a short time. Furthermore, from the viewpoint of preventing decomposition or deterioration of the polyphenol compound or biodegradable resin due to heat, the temperature is preferably 200° C. or lower, more preferably 190° C. or lower, particularly preferably 180° C. or lower, and most preferably 170° C. or lower.

[0103] As for the melt-kneading time, from the viewpoint of more reliably preventing the deterioration of the polyphenol compound and the biodegradable resin, unnecessarily long times should be avoided, and it is preferably 20 seconds or more and 20 minutes or less, more preferably 30 seconds or more and 15 minutes or less. Therefore, it is preferable to set the melt-kneading temperature and time conditions so as to satisfy these melt-kneading conditions.

[0104] The biodegradable resin composition may also be a composition obtained by kneading a masterbatch described below with other components.

[0105] <Masterbatch> The polyphenol compound may be mixed with the biodegradable resin not only directly but also as a masterbatch. Another embodiment of the present invention, the masterbatch (hereinafter also simply referred to as "masterbatch"), is a masterbatch containing the above-mentioned polyphenol compound and a carrier described below. Here, the masterbatch is a mixture in which a high concentration of additives is dispersed in a carrier in advance, and is used by diluting the additives by mixing with another resin. Mixing the masterbatch containing the polyphenol compound with the biodegradable resin makes it easier to adjust the amount of additive added in the composition, and a more uniform composition can be obtained.

[0106] Since the masterbatch contains the above-mentioned polyphenol compound, when used together with the biodegradable resin composition, the biodegradation rate can be adjusted so that the biodegradation is delayed and ultimately biodegraded without significantly changing the physical properties, such as the mechanical properties, of the biodegradable resin itself.

[0107] The carrier contained in the masterbatch is not particularly limited, but examples thereof include thermoplastic resins, rubber, inorganic particles such as talc or calcium carbonate, natural polymers such as starch or cellulose or modified forms thereof, water, organic solvents, and liquid resins. Among these, thermoplastic resins are preferred because they are easy to handle and allow polyphenol compounds to be uniformly mixed into the biodegradable resin. Biodegradable resins are more preferred from the viewpoint of reducing environmental impact. As the biodegradable resin, one or more biodegradable polyester resins selected from the group consisting of aliphatic polyester resins and aliphatic-aromatic polyester resins can be preferably used. As the aliphatic polyester resin, aliphatic polyester resins having aliphatic diol-derived structural units and aliphatic dicarboxylic acid-derived structural units as main structural units are particularly preferred because of their high thermal stability, excellent biodegradability in the natural environment, and excellent compatibility with polyphenol compounds. As the aliphatic polyester resin and the aliphatic-aromatic polyester resin, for example, the aliphatic polyester resins and aliphatic-aromatic polyester resins described above in the section on biodegradable resin compositions can be used.

[0108] The shape of the masterbatch is not particularly limited, but pellets, flakes, or powder are preferred because they are easy to handle, and pellets are particularly preferred because they can be easily supplied uniformly and stably to a kneader or molding machine together with the biodegradable resin.

[0109] The size of the masterbatch is not particularly limited and can be set appropriately depending on the mode of use. For example, from the viewpoint of stable supply to a molding machine or a kneading machine, a size of 0.004 cm ３ It is preferable that the thickness is 0.006 cm or more. ３ More preferably, it is 0.008 cm or more. ３ It is more preferable that the thickness is 0.1 cm or more, and from the viewpoint of uniformly dispersing the polyphenol compound, ３ Preferably, it is 0.08 cm or less. ３ More preferably, it is 0.06 cm or less. ３ It is even more preferable that:

[0110] The content ratio of the polyphenol compound in the masterbatch can effectively exhibit the biodegradation retarding effect relative to the amount of masterbatch added, and from the viewpoint of economical excellence, it is preferably 0.1 parts by mass or more relative to 100 parts by mass of the carrier, more preferably 1 part by mass or more, even more preferably 5 parts by mass or more, particularly preferably 10 parts by mass or more, and most preferably 20 parts by mass or more. Also, from the viewpoint of uniformly distributing the concentration of the polyphenol compound in the molded body, the content ratio is preferably 400 parts by mass or less relative to 100 parts by mass of the carrier, more preferably 300 parts by mass or less, even more preferably 200 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 50 parts by mass or less. Particularly preferably, the content ratio of the polyphenol compound having a molecular weight of 500 to 10,000 in the masterbatch is preferably 0.1 parts by mass or more relative to 100 parts by mass of the carrier, more preferably 1 part by mass or more, more preferably 5 parts by mass or more, particularly preferably 10 parts by mass or more, and most preferably 20 parts by mass or more. The content is preferably 400 parts by mass or less, more preferably 300 parts by mass or less, even more preferably 200 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 50 parts by mass or less, per 100 parts by mass of the carrier.

[0111] A preferred method for producing a masterbatch is to knead a polyphenol compound with a carrier in a kneader such as a twin-screw extruder, and then shred the resulting mixture to obtain pellets. When the carrier is a thermoplastic resin, it is preferable to heat the carrier to a temperature equal to or higher than its flow initiation temperature and melt-knead it. From the viewpoint of uniformly dispersing the polyphenol compound in a short time, the kneading temperature is preferably 70°C or higher, more preferably 90°C or higher, particularly preferably 110°C or higher, and most preferably 130°C or higher. On the other hand, from the viewpoint of preventing decomposition or deterioration of the polyphenol compound or resin due to heat, the temperature is preferably 200°C or lower, more preferably 190°C or lower, particularly preferably 180°C or lower, and most preferably 170°C or lower.

[0112] In addition to the above-mentioned components, the masterbatch may contain other components such as antistatic agents, antioxidants, light stabilizers, UV 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, or various additives such as slip agents (other components). The masterbatch may also contain functional additives such as freshness-preserving agents or antibacterial agents as other components. These other components can be blended arbitrarily within a range that does not impair the effects of the present invention, and one type may be used alone, or two or more types may be used in combination.

[0113] The masterbatch and biodegradable resin may be mixed in a predetermined ratio using a mixer such as a tumbler mixer, a V-type blender, or a Nauta mixer, and then fed to a molding machine. Alternatively, they may be melt-kneaded in advance using a kneader such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, or a kneader, and then fed to a molding machine. The temperature during melt-kneading is preferably 70°C or higher, more preferably 90°C or higher, particularly preferably 110°C or higher, and most preferably 130°C or higher, from the viewpoint of uniformly dispersing the raw materials in a short period of time. Furthermore, from the viewpoint of preventing decomposition or deterioration of the polyphenol compound or resin due to heat, the temperature is preferably 200°C or lower, more preferably 190°C or lower, particularly preferably 180°C or lower, and most preferably 170°C or lower.

[0114] Another embodiment of the use of the masterbatch according to the present invention is the use of the above-mentioned masterbatch as a biodegradation retarder for delaying the biodegradation of a biodegradable resin, more specifically, the use of the masterbatch as a biodegradation retarder for delaying the biodegradation of a biodegradable resin in a mixture with the biodegradable resin.

[0115] [Molded Article] A molded article according to another embodiment of the present invention is a molded article obtained by molding the biodegradable resin composition described above, or a molded article obtained by molding a biodegradable resin composition obtained by kneading the masterbatch described above with a biodegradable resin. The biodegradable resin composition can be molded by various molding methods applicable to general-purpose plastics. Examples of such molding methods include compression molding (compression molding, laminate molding, stampable molding), injection molding, extrusion molding or co-extrusion molding (film molding by inflation molding or T-die method, laminate molding, pipe molding, electric 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 rolling 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, spunbond method, etc.). Among these, injection molding, extrusion molding, compression molding, or hot press molding, particularly extrusion molding or injection molding, is preferably applied. As specific shapes of molded articles, application to sheets, films, and fibers is preferred.

[0116] Furthermore, a biodegradable resin molded article obtained by molding a biodegradable resin composition 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, or biocompatibility. Examples of secondary processing steps include embossing, painting, bonding, printing, metallizing (plating, etc.), machining, or surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.).

[0117] The method for producing the molded body is not particularly limited, and examples thereof include a method including a step of kneading the biodegradable resin composition described above, or a method including a step of mixing (preferably kneading) the masterbatch and the biodegradable resin described above. The mixing or kneading conditions can be the same as those described in the method for producing the composition described above. In addition, the mixing or kneading can be carried out after or while further adding the polyphenol compound, biodegradable resin, or other components described above.

[0118] A film according to another embodiment of the present invention is a film-like molded article, specifically comprising one or more biodegradable resin components (T) selected from the group consisting of aliphatic polyester resins, polyhydroxyalkanoates, and aliphatic-aromatic polyester resins, whose main structural units are structural units derived from aliphatic diols and structural units derived from aliphatic dicarboxylic acids, and a polyphenol compound containing 4 to 50 structural units in one molecule, each structural unit having 1 to 5 phenolic hydroxyl groups bonded to a single benzene ring. The conditions for the biodegradable resin component (T) and the polyphenol compound, as well as the conditions for the intended use and production method of the film, can be similarly applied to the conditions for the biodegradable resin component (T) and the polyphenol compound, as well as the intended use and production method of the molded article, as described above.

[0119] The thickness of the film is not particularly limited and can be set appropriately depending on the application, but for example, from the viewpoints of strength and ease of handling, it is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more, and from the viewpoints of biodegradability and cost, it is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less. The area of ​​the film is not particularly limited and can be set appropriately depending on the application and mode of use.

[0120] [Uses] The biodegradable resin molded articles are particularly suitable for use in agricultural and forestry materials, fishing materials, civil engineering materials, and the like, which are used outdoors, underground, underwater, or in wet environments. Specific examples include extrusion-molded articles (for example, film products such as agricultural mulch films and mushroom cultivation films, sheet products such as tree protection sheets and water-retaining sheets, and textile products such as fishing lines, fishing nets, aquaculture nets, vegetation nets, and ropes), and injection-molded articles (stakes, fasteners, fishing gear, seedling pots, or cultivation containers). They are also suitable for use in compost bags and garbage bags, which are expected to be stored for a certain period of time at home, in a business, or the like.

[0121] The present invention will be described in more detail below using examples and comparative examples, but 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 and 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 a combination of the above-mentioned upper or lower limit values ​​and the values ​​in the following examples or values ​​between the examples.

[0122] <Method for evaluating compatibility> The appearance of the strand in a molten state when the melt-kneaded resin composition was taken out was evaluated according to the following criteria: Good: Shows a transparent and uniform appearance. Fairly poor: Insoluble particles are visible in the transparent resin, but no particle irregularities are visible on the surface. Poor: At least the entire composition is cloudy, or particle irregularities are visible on the surface. If the evaluation is good, the resin and additives are uniformly mixed, so that the composition has good moldability when molded into a film or fiber, and a molded product with a good appearance and feel can be obtained.

[0123] <Marine biodegradability test method> Commercially available artificial seawater powder ("Marine Art SF-1" manufactured by Tomita Pharmaceutical Co., Ltd.) was dissolved in a specified amount of ion-exchanged water to prepare artificial seawater. Meanwhile, natural seawater was collected as an inoculum source from a sandy beach in Yokkaichi Port, Yokkaichi City, Mie Prefecture (near 34.94 degrees north latitude, 136.64 degrees east longitude) and filtered through a nylon mesh with an 11 μm mesh size. In addition, sea sand was collected from the same location, and sand grains that fell under a 2 mm mesh size sieve and over a 0.3 mm mesh size sieve were selected and washed with filtered seawater to remove floating matter. The sea sand was spread to a thickness of approximately 1 cm on the bottom of a glass aquarium (width 60 cm, depth 30 cm, height 23 cm) equipped with a seawater filtration and circulation device, a temperature control device, and an air stone, and approximately 30 L of the artificial seawater (depth approximately 17 cm) and approximately 200 mL of the natural seawater were added to form a test aquarium. After measuring the weight of the sheet cut into 30 mm squares, it was placed on the sand in the aquarium, and seawater was circulated while air was blown in from the air stone, and the water temperature was maintained at 28°C and left to stand for 8 weeks. The removed test specimen was then washed with tap water, air-dried, and the weight after the test was measured. The weight loss per surface area (mg / cm) was calculated by dividing the weight loss before and after the test by the total surface area of ​​both the front and back surfaces of the test specimen. ２ The weight loss per surface area (mg / cm) was calculated using the following formula: ２ ) = (weight loss (g) x 10 ３ ) / (30 x 30 x 2 x 10 －２ )

[0124] <Home compost biodegradability test> The resin composition formed into a sheet was cut into a 50 mm x 30 mm rectangle, and the rectangle was buried in a polyethylene Tupperware container containing a mixture of 20% RH gardening soil ("Flower and Vegetable Culture Soil" manufactured by Iris Ohyama Co., Ltd.) and compost (Inoculum for Biodegradation Tests, manufactured by Yawata Bussan Co., Ltd.) at a mass ratio of 1:1. The container was then closed and allowed to stand in a thermostatic chamber at 28° C. Each test piece was periodically removed and the weight change was measured to determine the weight retention (the ratio of the weight after a specified number of days to the weight before the test) was calculated.

[0125] <Film Property Tests> (Tensile Test) Test specimens were prepared from the produced films in accordance with ISO 527-3, and the tensile modulus, yield stress, tensile breaking strength, and tensile breaking elongation of the test specimens in the MD (machine direction) and TD (transverse direction) were measured. (Elmendorf Tear Test) Test specimens were prepared from the produced films in accordance with ISO 6383-2, and the tear strength (N) of the test specimens in the MD and TD was measured, and the tear strength (N / mm) was calculated by dividing the tear strength by the thickness (mm) of the test specimen. (Puncture Impact Test) The produced film was cut into a tape shape with a width of 110 mm to serve as a test piece, and using a punching impact tester manufactured by Toyo Seiki Seisaku-sho, 12 holes with a diameter of 50 mm were punched with an arm having a hemispherical shape with a diameter of 25 mm at the tip, and the energy (J) required for each punch was divided by the thickness (mm) of the test piece to measure the average value as the puncture impact strength (J / mm).

[0126] <40°C Biodegradability Test> A test was carried out in the same manner as the home compost biodegradability test, except that the temperature at which the sample was left standing was changed to 40°C.

[0127] <Film spreading test> In a field in Tsu City, Mie Prefecture, a film was spread on a ridge, both ends were covered with soil, and left as is for a certain period of time. The test was conducted from October 16, 2023 to December 28, 2023. The part buried in the soil was dug up and evaluated according to the following criteria. Good: The film had no holes or tears and did not tear easily when pulled. Poor: The film had holes or tears and easily tore when pulled.

[0128] [Examples 1 to 7, Comparative Examples 1 to 6] (Biodegradable Resin) The following aliphatic polyester resin (A)-1 was used as the biodegradable resin. Aliphatic polyester resin (A)-1: PTTMCC Biochem's "BioPBS FD92PM" (polybutylene succinate adipate (PBSA)) (Additives) The following materials were used as polyphenol compounds and comparative additives. Hydrolyzable tannin: "Tannic acid" from Fujifilm Wako Pure Chemical Corporation (the number of structures in which 1 to 5 phenolic hydroxyl groups are bonded to one benzene ring and the molecular weight are as described above in the section "Tannic acid"). Condensed tannin: "Mimosa tannin" from Kawamura Tsusho Co., Ltd. (the number of structures in which 1 to 5 phenolic hydroxyl groups are bonded to one benzene ring and the molecular weight are as described above in the section "Condensed tannin".) Catechin: "D-(+)-catechin hydrate" from Nacalai Tesque Inc. (the number of structures in which 1 to 5 phenolic hydroxyl groups are bonded to one benzene ring = 2, molecular weight = 290). Propyl gallate: "Propyl gallate" from Tokyo Chemical Industry Co., Ltd. (the number of structures in which 1 to 5 phenolic hydroxyl groups are bonded to one benzene ring = 1, molecular weight = 212). Chitosan: "Koyo Chitosan" from Koyo Chemical Co., Ltd. SK-50" was crushed and passed through a sieve with 300 μm openings (number of structures with 1 to 5 phenolic hydroxyl groups bonded to one benzene ring = 0)

[0129] (Tannin Analysis) Mass spectrometry of the hydrolyzable tannins and condensed tannins was performed using a matrix-assisted laser desorption / ionization time-of-flight mass spectrometer under the following measurement conditions. Apparatus: JMS-S3000 (JEOL Ltd.) Laser wavelength: 349 nm Ion focusing mode: Spiral mode Detected ion: Positive ion Scanning mass range: 720-10,000 (m / z) Matrix: 2,5-dihydroxybenzoic acid A sample was dissolved in an acetonitrile / water (volume ratio 2 / 1) solution containing 0.1% trifluoroacetic acid to prepare an approximately 0.1% solution. Separately, a 1% solution was prepared by dissolving the matrix in ethanol / water (volume ratio 4 / 1). Equal volumes of the sample solution and matrix solution were mixed, and 1 μL was taken, dried on a sample plate, and subjected to measurement. For hydrolyzable tannins, a molecule in which 4 to 12 gallate ester groups are bound to glucose was used. The NaCl-containing 2,5-dihydroxybenzoic acid solution was added to the 2,5-dihydroxybenzoic acid solution. ＋ The peaks at m / z = 811, 963, 1115, 1267, 1419, 1571, 1723, 1875, and 2027 correspond to the addition of ions, and the ... ＋ Peaks at m / z = 793, 945, 1097, 1249, 1401, 1553, and 1705 were detected, which correspond to the adducts of ions. ＋ Peaks at m / z = 889, 1177, 1465, and 1753, corresponding to the ions added, peaks at m / z = 905, 1193, 1481, and 1769, corresponding to the ions in which one -H group in each molecule has been replaced with an -OH group, and peaks at m / z = 873, 1161, 1449, and 1737, corresponding to the ions in which one -OH group in each molecule has been replaced with an -H group, were detected.

[0130] The biodegradable resin and various additives were mixed in the proportions shown in Table 1, and the mixture was melt-kneaded for 4 minutes at 170°C under a nitrogen atmosphere using a small twin-screw kneader (DSM Xplore Micro 15cc Twin Screw Compounder). The resulting resin composition was then removed as a molten strand. The compatibility of the resin and additives was evaluated, and the results are shown in Table 1.

[0131]

[0132] The strand-like resin composition obtained above was allowed to cool, chopped into pellets, and then molded into sheets with a thickness of approximately 120 μm using a hot press molding machine set at 170° C. The sheets obtained from the resin compositions of Examples 1 to 3, 5 to 7 and Comparative Examples 1 to 5 were subjected to a marine biodegradability test, and the results are shown in Table 2. In addition, the sheets of Examples 1, 3, 5, and 7 and Comparative Examples 1 to 5 were subjected to a home compost biodegradability test, and the results are shown in FIGS.

[0133]

[0134] [Examples 8 to 13, Comparative Example 7] Molded articles of the resin compositions shown in Table 3 were obtained in the same manner as in the above Examples, except that the aliphatic polyester resin (A)-2 (polybutylene succinate sebacate; PBSSe) obtained in Production Example 1 below was used as the biodegradable resin. Marine biodegradability tests were conducted on these molded articles, and the results are shown in Table 3. Home compost biodegradability tests were also conducted on these molded articles, and the results are shown in Figures 4 and 5.

[0135] <Production Example 1> (Production method of PBSSe) 1,4-butanediol (100.1 g), succinic acid (83.4 g), sebacic acid (17.7 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 while reducing the pressure, and the reaction was continued for 5 hours and 15 minutes. The resulting polymer was extracted in the form of a strand into water and cut to obtain pellets of PBSSe. １ The molar ratio of succinic acid units to sebacic acid units determined by H-NMR (nuclear magnetic resonance spectroscopy) was 89 / 11.

[0136]

[0137] [Examples 14 and 15, Comparative Example 8] Molded articles of the resin compositions shown in Table 4 were obtained in the same manner as in the above Examples, except that the following polyhydroxyalkanoate (D) was used as the biodegradable resin. Marine biodegradability tests were conducted on these molded articles, and the results are shown in Table 4. Polyhydroxyalkanoate (D): Kaneka Corporation "PHBH X131A" (poly(3-hydroxybutyrate / 3-hydroxyhexanoate) (PHBH))

[0138]

[0139] [Examples 16 and 17, Comparative Example 9, Reference Examples 1 to 3] Molded articles of the resin compositions shown in Table 5 were obtained in the same manner as in the above Examples, except that the following aliphatic-aromatic polyester resin (B) and aliphatic oxycarboxylic acid resin (C) were used as the biodegradable resins. These molded articles were subjected to a 40°C biodegradability test, and the results are shown in Figures 6 and 7. Aliphatic-aromatic polyester resin (B): BASF "Ecoflex C1200" (polybutylene adipate terephthalate (PBAT)) Aliphatic oxycarboxylic acid resin (C): NatureWorks "Ingeo 4032D" (polylactic acid (PLA))

[0140]

[0141] [Examples 18 to 20, Comparative Example 10] (Production Examples of Polyphenol Compound Masterbatch) The following aliphatic polyester resin (A)-3 and the hydrolyzable tannin were fed at a mass ratio of 75:25 to a twin-screw extruder having a screw diameter of 30 mm and an L / D ratio of 52.5, melt-kneaded at a set temperature of 150°C, extruded into a strand shape, cooled in a water bath, and then shredded into pellets to produce a polyphenol compound masterbatch. Aliphatic polyester resin (A)-3: PTTMCC Biochem "BioPBS FZ91PB" (polybutylene succinate (PBS))

[0142] (Production Example of Antiblocking Agent Masterbatch) The aliphatic-aromatic polyester resin (B), talc, and erucic acid amide described below were fed to a twin-screw extruder having a screw diameter of 30 mm and an L / D ratio of 52.5 in a mass ratio of 89.6:10:0.4, melt-kneaded at a set temperature of 150°C, extruded into a strand shape, cooled in a water tank, and then shredded into pellets to produce an antiblocking agent masterbatch. Talc: "Microace K-1" manufactured by Nippon Talc Co., Ltd. Erucic acid amide: "Diamid L-200" manufactured by Mitsubishi Chemical Corporation

[0143] The raw resins and master batches were mixed in the proportions shown in Table 6, fed into an inflation molding machine equipped with a 60 mm diameter annular die, and molded at a set temperature of 160°C and a blow ratio of 2.5 to obtain films with a thickness of 18 μm. No foreign matter was observed in any of the films, and the surfaces were smooth. The proportions of resins and additives contained in the films are also shown in Table 6. The obtained films were subjected to film property tests, 40°C biodegradability tests (weight retention after 16 weeks), and film extension tests, and the results are shown in Table 6.

[0144]

[0145] Tables 2-4 and Figures 1, 2, 4-6 show that polyphenol compounds containing 4 to 50 structures in one molecule, each having 1 to 5 phenolic hydroxyl groups bonded to a single benzene ring, can be added to a biodegradable resin selected from the group consisting of aliphatic polyester resins (A), aliphatic-aromatic polyester resins (B), and polyhydroxyalkanoates (D), whose main structural units are aliphatic diol-derived structural units and aliphatic dicarboxylic acid-derived structural units, to slow biodegradation and ultimately produce a biodegradable resin composition that is almost completely biodegradable. Furthermore, Table 1 shows that hydrolyzable tannins in particular have good compatibility with biodegradable resins, and sheet-shaped molded articles obtained using biodegradable resin compositions containing hydrolyzable tannins actually had good moldability, feel, and appearance. On the other hand, Figure 7 shows that the compound does not have a sufficient biodegradation-retarding effect on polylactic acid, a biodegradable polyester resin not included in these groups. 3, catechin and propyl gallate, which have less than four structures in which one to five phenolic hydroxyl groups are bonded to one benzene ring, do not have the effect of delaying biodegradation. Furthermore, Table 6 shows that by using a masterbatch containing the polyphenol compound, it is possible to produce a film with sufficient physical properties and appearance, and the resulting film biodegrades slowly, maintaining sufficient strength for a certain period of time even in an actual field.

Claims

1. A master batch comprising a polyphenol compound having 4 to 50 structures in one molecule, each structure having 1 to 5 phenolic hydroxyl groups bonded to one benzene ring, and a thermoplastic resin.

2. The masterbatch according to claim 1, comprising 0.1 parts by mass or more and 400 parts by mass or less of the polyphenol compound per 100 parts by mass of the thermoplastic resin.

3. The masterbatch according to claim 1, comprising 5 parts by mass or more and 400 parts by mass or less of the polyphenol compound per 100 parts by mass of the thermoplastic resin.

4. The masterbatch according to claim 1, comprising more than 10 parts by mass and not more than 400 parts by mass of the polyphenol compound per 100 parts by mass of the thermoplastic resin.

5. The masterbatch according to claim 1, wherein the molecular weight of the polyphenol compound is 500 or more.

6. The master batch according to claim 1, wherein the polyphenol compound is a polyphenol compound containing, per molecule, 4 to 50 structures in which 2 to 3 phenolic hydroxyl groups are bonded to one benzene ring.

7. The masterbatch according to claim 1, wherein the thermoplastic resin is a biodegradable resin.

8. The masterbatch according to claim 7, wherein the biodegradable resin comprises one or more biodegradable polyester resins selected from the group consisting of aliphatic polyester resins and aliphatic-aromatic polyester resins.

9. The masterbatch according to claim 7, wherein the biodegradable resin comprises one or more biodegradable polyester resins selected from the group consisting of aliphatic polyester resins having as their main structural units structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid, and aliphatic-aromatic polyester resins.

10. The masterbatch of claim 1, wherein the polyphenol compound is a tannin.

11. The masterbatch of claim 10, wherein the tannin is a hydrolyzable tannin.

12. The masterbatch of claim 11, wherein said hydrolyzable tannin is tannic acid.

13. Use of the masterbatch according to any one of claims 1 to 12 as a biodegradation retarder for retarding the biodegradation of a biodegradable resin.

14. A method for producing a molded article, comprising the step of mixing the masterbatch according to any one of claims 1 to 12 with a biodegradable resin.

15. A biodegradable resin composition comprising one or more biodegradable resin components (T) selected from the group consisting of aliphatic polyester resins, polyhydroxyalkanoates, and aliphatic-aromatic polyester resins, whose main structural units are structural units derived from an aliphatic diol and structural units derived from an aliphatic dicarboxylic acid, and a polyphenol compound containing 4 to 50 structures in one molecule, each structure having 1 to 5 phenolic hydroxyl groups bonded to one benzene ring, wherein the content of the biodegradable resin component (T) in the biodegradable resin composition is more than 20 mass% and 99.999 mass% or less, and the polyphenol compound is contained in a ratio of 0.001 mass parts to 10 mass parts per 100 mass parts of the biodegradable resin component (T).

16. The biodegradable resin composition according to claim 15, wherein the molecular weight of the polyphenol compound is 500 or more.

17. The biodegradable resin composition according to claim 15, wherein the polyphenol compound is a polyphenol compound containing, per molecule, 4 to 50 structures in which 2 to 3 phenolic hydroxyl groups are bonded to one benzene ring.

18. The biodegradable resin composition according to claim 15, wherein the polyphenol compound is tannin.

19. The biodegradable resin composition according to claim 18, wherein the tannin is a hydrolyzable tannin.

20. The biodegradable resin composition according to claim 19, wherein the hydrolyzable tannin is tannic acid.

21. The biodegradable resin composition according to claim 15, wherein the biodegradable resin component (T) comprises an aliphatic polyester resin having as main structural units a structural unit derived from an aliphatic diol and a structural unit derived from an aliphatic dicarboxylic acid.

22. The biodegradable resin composition according to claim 15, wherein the biodegradable resin component (T) comprises a polyhydroxyalkanoate.

23. The biodegradable resin composition according to claim 15, wherein the biodegradable resin component (T) comprises an aliphatic-aromatic polyester resin.

24. A molded article obtained by molding the biodegradable resin composition according to claim 15.

25. The molded article according to claim 24, which is an agricultural and forestry material, a fishing material, or a civil engineering material.

26. A film comprising one or more biodegradable resin components (T) selected from the group consisting of aliphatic polyester resins having as their main structural units structural units derived from aliphatic diols and structural units derived from aliphatic dicarboxylic acids, polyhydroxyalkanoates, and aliphatic-aromatic polyester resins, and a polyphenol compound containing, per molecule, 4 to 50 structures in which 1 to 5 phenolic hydroxyl groups are bonded to one benzene ring.

27. The film of claim 26, wherein the polyphenol compound has a molecular weight of 500 or more.

28. The film according to claim 26, wherein the polyphenol compound is a polyphenol compound containing, per molecule, 4 to 50 structures in which 2 to 3 phenolic hydroxyl groups are bonded to one benzene ring.

29. The film of claim 26, wherein the polyphenol compound is a tannin.

30. The film of claim 29, wherein the tannin is a hydrolyzable tannin.

31. The film of claim 30, wherein the hydrolyzable tannin is tannic acid.

32. The film according to claim 26, wherein the biodegradable resin component (T) contains an aliphatic polyester resin having as main structural units a structural unit derived from an aliphatic diol and a structural unit derived from an aliphatic dicarboxylic acid.

33. The film of claim 26, wherein the biodegradable resin component (T) comprises a polyhydroxyalkanoate.

34. The film of claim 26, wherein the biodegradable resin component (T) comprises an aliphatic-aromatic polyester resin.

35. The film according to claim 26, which is an agricultural or forestry material, a fishing material, or a civil engineering material.

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