Resin composition

Abstract

Disclosed is a resin composition which contains a 3-hydroxyalkanoic acid-based polymer represented by formula (I) and a polyester-based polymer, wherein: the polyester-based polymer is composed of a monomer unit that comprises only a polyhydric alcohol component and a dicarboxylic acid component; at least a part of a terminal of the polyester-based polymer is blocked with a residue of a monoalcohol and / or a residue of a monocarboxylic acid; a polyhydric alcohol constituting the polyhydric alcohol component comprises 3-methyl-1,5-pentanediol (MPD) and / or trimethylolpropane (TMP); a dicarboxylic acid constituting the dicarboxylic acid component comprises adipic acid or sebacic acid; the monoalcohol is 2-ethylhexanol; and the monocarboxylic acid is acetic acid. (In formula (I), the ratio (k / p) is 70 / 30 to 99 / 1.)

Description

resin composition

[0001] The present invention relates to a resin composition.

[0002] In recent years, due to the demand for environmentally friendly, sustainable biomass resins and biodegradable resins, active development of these resins has been underway. In this context, polyhydroxyalkanoic acid polymers, which are biomass and biodegradable resins, are used in a wide range of fields, including packaging, food service, biomedical applications, and agriculture. However, polyhydroxyalkanoic acid polymers are generally known to be more brittle than petroleum-based resins and to have inferior flexibility (elongation) and impact resistance. Therefore, the use of polyhydroxyalkanoic acid polymers as resin materials is sometimes limited. In this context, attempts to improve the physical properties of biomass resins and biodegradable resins have been made, for example, to impart flexibility while suppressing bleed-out (see, for example, Patent Documents 1 and 2).

[0003] JP 2005-023091 A International Publication No. 2023 / 026758

[0004] However, Patent Documents 1 and 2 only mainly consider polylactic acid polymers as biomass resins and biodegradable resins, including in the examples, and do not specifically or sufficiently consider polyhydroxyalkanoic acid polymers, particularly 3-hydroxyalkanoic acid polymers, from the viewpoint of imparting impact resistance at low temperatures, etc.

[0005] In view of the above, an object of the present invention is to provide a resin composition having improved impact resistance at low temperatures.

[0006] As a result of intensive research to solve the above problems, the present inventors have conceived the following invention and found that the above problems can be solved.

[0007] [1] A resin composition comprising a 3-hydroxyalkanoic acid polymer represented by the following formula (I) and a polyester polymer, (In formula (I), the ratio of k to p (k / p) is 70 / 30 to 99 / 1.) The polyester polymer is composed of monomer units consisting only of a polyhydric alcohol component and a dicarboxylic acid component, and at least a portion of the ends of the polyester polymer are blocked with a residue of a monoalcohol and / or a residue of a monocarboxylic acid, and the polyhydric alcohol of the polyhydric alcohol component is MPD (3-methyl-1,5-pentanediol) and / or TMP (trimethylolpropane), and the dicarboxylic acid of the dicarboxylic acid component is adipic acid or sebacic acid, and the monoalcohol is 2-ethylhexanol, and the monocarboxylic acid is acetic acid. [2] The resin composition according to item [1] above, containing 5 to 30 parts by mass of the polyester polymer per 100 parts by mass of the 3-hydroxyalkanoic acid polymer. [3] The resin composition according to [1] or [2] above, wherein the weight-average molecular weight of the 3-hydroxyalkanoic acid polymer is 50,000 to 3,000,000. [4] The resin composition according to any one of [1] to [3] above, wherein the ratio of the molar amount of MPD to the total amount of the molar amounts of MPD and TMP contained in the polyester polymer is 0.20 to 1.00 and the ratio of the molar amount of TMP to the total amount of the molar amounts of MPD and TMP is 0 to 0.80. [5] The resin composition according to any one of [1] to [4] above, wherein the polyester polymer has a hydroxyl value of 20 mg KOH / g or less and an acid value of 15 mg KOH / g or less. [6] The resin composition according to any one of [1] to [5] above, wherein the number-average molecular weight of the polyester polymer is 300 to 4,000. [7] The resin composition according to any one of [1] to [6] above, wherein the polyhydric alcohol contained in the polyester polymer is the MPD and the TMP. [8] The resin composition according to any one of the above [1] to [6], wherein the polyhydric alcohol contained in the polyester polymer is the MPD.

[0008] According to the present invention, it is possible to provide a resin composition having improved impact resistance at low temperatures.

[0009] The following describes an embodiment of the present invention. However, the embodiment described below is merely an example for embodying the technical concept of the present invention, and the present invention is not limited to the following description. In this specification, preferred embodiments are shown, but a combination of two or more of the individual preferred embodiments is also a preferred embodiment. For matters indicated as numerical ranges, when there are several numerical ranges, the lower limit and upper limit can be selectively combined to form a preferred embodiment. Furthermore, when a numerical range is described as "XX to YY," it means "XX or more and YY or less." In this specification, "~ unit" (where "~" indicates a polymer) means "a structural unit derived from ~." For example, "monomer unit" means "a structural unit derived from a monomer."

[0010] [Resin Composition] The resin composition of the present embodiment contains a 3-hydroxyalkanoic acid polymer represented by the following formula (I) and a polyester polymer. (In formula (I), the ratio of k to p (k / p) is 70 / 30 to 99 / 1.) The polyester polymer is composed of monomer units consisting only of a polyhydric alcohol component and a dicarboxylic acid component, and at least a portion of the ends of the polyester polymer are blocked with a monoalcohol residue and / or a monocarboxylic acid residue. The polyhydric alcohol of the polyhydric alcohol component is MPD (3-methyl-1,5-pentanediol) and / or TMP (trimethylolpropane), and the dicarboxylic acid of the dicarboxylic acid component is adipic acid or sebacic acid. The monoalcohol is 2-ethylhexanol, and the monocarboxylic acid is acetic acid. After extensive investigations, the present inventors have found that a resin composition containing a 3-hydroxyalkanoic acid polymer and a specific polyester polymer can improve impact resistance at low temperatures.

[0011] The reason why the resin composition of this embodiment has good elongation and impact resistance at low temperatures is unclear, but is presumed to be as follows. Because the polyester polymer contains an ester structure, it is likely to have moderate compatibility with a 3-hydroxyalkanoic acid polymer, which also contains an ester structure. Furthermore, by ester-modifying the terminal hydroxyl groups of an amorphous, flexible polyester polymer with a low glass transition temperature Tg, compatibility with the 3-hydroxyalkanoic acid polymer is further enhanced, and elongation and impact resistance at low temperatures are thought to be improved. In the present invention, "amorphous" refers to a polyester polymer that has been melted and dried and kept at room temperature for 5 to 10 days, then cooled using a differential scanning calorimeter (DSC) to a temperature of -50°C or lower, preferably -100°C or lower, at a rate of -10°C / min or higher, and then held at that temperature for 5 to 15 minutes. After that, when the DSC is again measured at a heating rate of 10°C / min to a temperature at which melt molding is possible, preferably 150°C or higher, no peak of at least 0.5 J / 40 g is observed, other than a change in heat capacity due to glass transition. The glass transition temperature Tg of the polyester polymer is preferably −40° C. or lower, more preferably −50° C. or lower, and even more preferably −60° C. or lower.

[0012] <3-Hydroxyalkanoic Acid Polymer> The 3-hydroxyalkanoic acid polymer of this embodiment is represented by the following general formula (I).

[0013]

[0014] <k / p> The ratio of k to p (k / p) represents the ratio of each structural unit and is 70 / 30 to 99 / 1. When k / p is 70 / 30 or more, molded articles produced using the resin composition have sufficient strength and are highly practical, while when k / p is 99 / 1 or less, the resin composition exhibits good impact resistance. In this specification, "k and p" are values ​​determined by gas chromatography measurement using the following method. 2 mL of a sulfuric acid-methanol mixture (volume ratio 15:85) and 2 mL of chloroform are added to 20 mg of a 3-hydroxyalkanoic acid polymer, the mixture is sealed, and heated at 100°C for 140 minutes to obtain a methyl ester of a 3-hydroxyalkanoic acid polymer 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 carbon dioxide generation ceases. Subsequently, 4 mL of diisopropyl ether was added and mixed thoroughly, followed by centrifugation, and the monomer unit composition ratio of the polyester decomposition product in the supernatant was analyzed under the following measurement conditions: (Measurement Conditions) Apparatus: Gas chromatograph GC-17A (Shimadzu Corporation) Capillary column: NEUTRA BOND-1 (GL Sciences Inc., column length 25 m, column inner diameter 0.25 mm, liquid film thickness 0.4 μm)

[0015] <Number Average Molecular Weight (Mn)> The number average molecular weight of the 3-hydroxyalkanoic acid polymer is preferably 20,000 to 1,000,000, and more preferably 50,000 to 700,000. When the number average molecular weight is within the above range, the viscosity of the resin composition is prevented from becoming too low or too high, improving the handleability and productivity during molding.

[0016] <Weight-average molecular weight (Mw)> The weight-average molecular weight of the 3-hydroxyalkanoic acid polymer is preferably 50,000 to 3,000,000, and more preferably 100,000 to 1,500,000. When the weight-average molecular weight is within the above range, the viscosity of the resin composition is prevented from becoming too low or too high, improving the handleability and productivity during molding.

[0017] <Molecular Weight Distribution (Mw / Mn)> The molecular weight distribution (Mw / Mn) of the 3-hydroxyalkanoic acid polymer is preferably 1.0 to 3.0, more preferably 1.1 to 2.0, and even more preferably 1.2 to 1.8.

[0018] <Polyester-Based Polymer> The polyester-based polymer is composed of monomer units consisting only of a polyhydric alcohol component and a dicarboxylic acid component, and the terminals are capped with a monoalcohol residue and / or a monocarboxylic acid residue. Alternatively, the terminals are capped via at least one residue selected from the monoalcohol residue and the monocarboxylic acid residue, and a monomer unit consisting only of the polyhydric alcohol component and the dicarboxylic acid component. Specifically, for example, the terminals may be capped only with an acetic acid residue or a 2-ethylhexanol residue. Furthermore, some of the terminals may not be capped with the monoalcohol residue or the monocarboxylic acid residue.

[0019] The polyhydric alcohol of the polyhydric alcohol component is MPD (3-methyl-1,5-pentanediol) and / or TMP (trimethylolpropane).

[0020] The dicarboxylic acid of the dicarboxylic acid component is adipic acid or sebacic acid.

[0021] The monoalcohol is 2-ethylhexanol and the monocarboxylic acid is acetic acid.

[0022] In an embodiment, the polyhydric alcohol contained in the polyester polymer is preferably MPD and TMP.

[0023] In another embodiment, the polyhydric alcohol contained in the polyester polymer is preferably MPD.

[0024] In still another embodiment, from the viewpoint of exhibiting even better biodegradability, it is preferable that either only monomer units containing the above-mentioned polyhydric alcohol (MPD) component and dicarboxylic acid (adipic acid or sebacic acid) component, or monomer units containing the above-mentioned polyhydric alcohol (MPD) component and dicarboxylic acid (adipic acid or sebacic acid) component and monomer units containing the above-mentioned polyhydric alcohol (TMP) component and dicarboxylic acid (adipic acid or sebacic acid) component coexist in the polyester polymer.

[0025] It is preferable that the ratio of the molar amount of MPD to the total amount of the molar amounts of MPD and TMP contained in the polyester polymer is 0.20 to 1.00, and the ratio of the molar amount of TMP to the total amount of the molar amounts of MPD and TMP is 0 to 0.80. When the ratio of the molar amount of MPD and the molar amount of TMP are within these ranges, impact resistance at low temperatures is easily exhibited.

[0026] As an embodiment, from the viewpoint of storage stability, the acid value of the polyester polymer is preferably 15 mgKOH / g or less, more preferably 10 mgKOH / g or less, and even more preferably 5 mgKOH / g or less. The acid value of the polyester polymer is measured according to JIS K1557-1:2007. As an embodiment, from the viewpoint of compatibility, the hydroxyl value of the polyester polymer is preferably 20 mgKOH / g or less, more preferably 10 mgKOH / g or less, and even more preferably 5 mgKOH / g or less. The hydroxyl value of the polyester polymer is measured according to JIS K1557-1:2007.

[0027] From the viewpoint of achieving both storage stability and compatibility, the acid value and hydroxyl value of the polyester polymer are preferably 15 mgKOH / g or less and 20 mgKOH / g or less, more preferably 10 mgKOH / g or less and 10 mgKOH / g or less, and even more preferably 5 mgKOH / g or less and 5 mgKOH / g or less.

[0028] <Number Average Molecular Weight of Polyester Polymer> From the viewpoint of improving impact resistance at low temperatures, the number average molecular weight of the polyester polymer is preferably 300 or more, more preferably 350 or more, even more preferably 400 or more, even more preferably 450 or more, and even more preferably 500 or more. From the viewpoint of moldability and compatibility with the 3-hydroxyalkanoic acid polymer, it is preferably 4,000 or less, more preferably 3,500 or less, and even more preferably 3,000 or less. In one aspect of the present invention, the number average molecular weight of the polyester polymer is preferably 300 to 4,000, more preferably 400 to 3,500, even more preferably 450 to 3,000, and even more preferably 500 to 2,500. The number average molecular weight of the polyester polymer can be determined in terms of standard polystyrene by gel permeation chromatography (GPC). When using a commercially available product, the catalog value may be used.

[0029] The resin composition of this embodiment preferably contains 5 to 30 parts by mass, more preferably 6 to 28 parts by mass, even more preferably 7 to 25 parts by mass, and even more preferably 8 to 20 parts by mass of the polyester polymer per 100 parts by mass of the 3-hydroxyalkanoic acid polymer. If the content is within this range, the resin composition can have even better impact resistance at low temperatures.

[0030] The total content of the 3-hydroxyalkanoic acid polymer and the polyester polymer in the resin composition of this embodiment is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and even more preferably 98% by mass or more, and may be 100% by mass. The effects of the present invention are more significantly exhibited at this content.

[0031] <Additives> The resin composition of this embodiment may contain additives in addition to the 3-hydroxyalkanoic acid polymer and the polyester polymer. Examples of additives include cellulose nanofibers, natural fibers such as straw, inorganic fillers, softeners, heat aging inhibitors, antioxidants, hydrolysis resistance inhibitors, light stabilizers, antistatic agents, release agents, flame retardants, foaming agents, pigments, dyes, brighteners, UV absorbers, lubricants, and impact modifiers. These may be used alone or in combination of two or more. When using the above additives, the content of the additives in the resin composition may be determined appropriately depending on the desired physical properties of the resin composition.

[0032] <Method for Producing Resin Composition> The method for producing the resin composition of this embodiment is not particularly limited. For example, the resin composition can be produced by uniformly mixing a 3-hydroxyalkanoic acid polymer, a polyester polymer, and, if necessary, additives. Examples of mixing methods include melt-kneading using a single-screw extruder, a multi-screw extruder, a Banbury mixer, a heated roll, a Brabender, various kneaders, or the like, or melt-kneading each component by feeding it through separate inlets. Pre-blending may also be performed before melt-kneading. Examples of pre-blending methods include using a mixer such as a Henschel mixer, a high-speed mixer, a V-blender, a ribbon blender, a tumbler blender, or a conical blender. The temperature during melt-kneading is preferably limited to approximately 185°C, taking into account the melting points and decomposition temperatures of the 3-hydroxyalkanoic acid polymer and the polyester polymer. Therefore, the temperature may be, for example, approximately 100°C to 185°C, or may be selected arbitrarily within the range of 120°C to 180°C.

[0033] [Molded Article] The present invention provides a molded article made from a resin composition. The shape of the molded article may be any molded article that can be produced using the resin composition of this embodiment, and examples of the molded article include molded articles in various shapes such as pellets, films, sheets, plates, pipes, tubes, bottles, fibers, rods, fine particles, particles, and foams. The method for producing these molded articles is not particularly limited, and they can be molded by known molding methods such as injection molding, blow molding, press molding, extrusion molding, calendar molding, and molding using a 3D printer.

[0034] [Uses] A 3-hydroxyalkanoic acid polymer can improve impact resistance at low temperatures by mixing it with a polyester polymer to form a resin composition. Therefore, the present invention provides a modifier for 3-hydroxyalkanoic acid polymers, which comprises a polyester polymer. In addition, a preferred embodiment is the use of a polyester polymer as a modifier for 3-hydroxyalkanoic acid polymers.

[0035] The resin composition of this embodiment can be used for various purposes, including, but not limited to, paper, film, sheet, tube, plate, rod, container such as bottle container, food tray, bag, part, etc.

[0036] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0037] [Measurement and Evaluation Methods] Various physical properties were measured or evaluated by the following methods.

[0038] <Number Average Molecular Weight of Polyester Polymer> The polyester polymers (A-1) to (A-6) obtained in the Production Examples were used as samples, and the number average molecular weight (Mn) was determined by gel permeation chromatography (GPC) in terms of molecular weight in terms of standard polystyrene. The specific measurement method is as follows. A tetrahydrofuran (THF) solution was used as the eluent. 10 mg of the sample, calculated as resin, was weighed out and dissolved in 1 mL of the eluent. The solution was passed through a 0.2 μm membrane filter to prepare a measurement sample. The measurement conditions were as follows. (Measurement Conditions) Apparatus: HLC-EcoSEC8320GPC (manufactured by Tosoh Corporation) Column: Three columns, KF-803, KF-802.5, and KF-802 (manufactured by Showa Denko K.K.), were connected in series. Eluent: tetrahydrofuran Flow rate: 0.9 mL / min Sample injection volume: 30 μL Column temperature: 40°C Standard polystyrene: PSt Oligomer Kit (molecular weight 589 to 98,900) manufactured by Tosoh Corporation was used for quintic approximation. Detector: RI detector

[0039] <Weight-average molecular weight of 3-hydroxyalkanoic acid polymer> The weight-average molecular weight (Mw) of the 3-hydroxyalkanoic acid polymer was determined by gel permeation chromatography (GPC) in terms of standard polystyrene. The specific measurement method is as follows. (Measurement conditions) Apparatus: High-performance liquid chromatograph LC-20A (Shimadzu Corporation) Column: K-G 4A (1 column) and K-806M (2 columns) (Showa Denko K.K.) connected in series. Eluent: Chloroform Flow rate: 1.0 mL / min Sample injection amount: 100 μL Column temperature: 40°C Standard polystyrene: Polystyrene standard (molecular weight: 2,880 to 6,570,000) manufactured by Agilent Technologies Inc. was used for quintic approximation. Detector: RI detector

[0040] <Hydroxyl Value and Acid Value of Polyester Polymer> The hydroxyl value and acid value were measured by indicator titration according to Method A of JIS K 1557-1:2007.

[0041] <Impact Resistance Test> (1) Preparation of Test Pieces for Impact Resistance Test The resin compositions obtained in the examples and comparative examples were decompressed to -0.1 MPaG using a vacuum hot press (Imoto Machinery Co., Ltd. "IMC-183B") and an oil rotary pump. After preheating at 165 ° C for 5 minutes, they were pressed at 8 MPa for 3 minutes. Then, they were pressed at 8 MPa for 3 minutes using a cooling press equipped with water flow cooling to prepare a 1.0 mm thick pressed plate. A 50 × 50 mm square piece was cut out from the obtained pressed plate to serve as a test piece. (2) Impact Resistance Test The above test pieces were stored for 10 hours or more in a low-temperature constant temperature bath (ETAC Corporation "HIFLEX FL714C") adjusted to each test temperature (23 ° C, 0 ° C, -15 ° C) shown in Table 2, and the humidity was conditioned. The test specimens after humidity conditioning were subjected to measurements using a DuPont impact resistance tester (manufactured by Taiyu Kizai Co., Ltd.) according to the following steps (a) to (d) to evaluate their impact resistance. (a) Using a support rod, a 1 kg weight was set 0.5 m from the support base. (b) The test specimen was removed from the thermostatic chamber to an environment of 23°C and 49% relative humidity, and the test specimen was placed between the support base and the hammer. (c) The pressure rod was pulled out, and the weight was dropped toward the hammer. Here, the time from removing the test specimen in (b) to dropping the weight in (c) was 5 seconds or less. (d) After the weight was dropped, the test specimen was checked for "break" or "not break." The above steps (a) to (d) were performed on 20 test specimens, and the specimens were evaluated according to the following criteria. G: 10 or more test specimens did not break. NG: Fewer than 10 test specimens did not break.

[0042] [Materials] The materials used in the examples and comparative examples are as follows.

[0043] (3-Hydroxyalkanoic acid polymer) [Production Example I] Alcaligenes eutrophus AC32 (Accession No. FERM BP-6038), into which Aeromonas caviae-derived polyhydroxyalkanoic acid synthase genes had been introduced, was cultured by the method described in Example 1 of JP-A 2001-340078 to produce a 3-hydroxyalkanoic acid polymer. That is, Alcaligenes eutrophus AC32 (Accession No. FERM BP-6038) (hereinafter abbreviated as "AC32 strain") was cultured as follows. The composition of the medium was 1 w / v% meat extract, 1 w / v% Bacto-Trypton, 0.2 w / v% yeast extract, and 0.9 w / v% Na. ２ HPO4・12H ２ O, 0.15w / v% KH ２ P.O. ４ The composition of the polyester production medium was 1.1 w / v% Na ２ HPO ４ ・12H ２ O, 0.19w / v% KH ２ P.O. ４ , 0.6w / v% (NH ４ ) ２ SO ４ , 0.1w / v% MgSO ４ ・7H ２ 0, 0.5 v / v% trace metal salt solution (1.6 w / v% FeCl in 0.1 N hydrochloric acid) ３ ・6H ２ O, 1w / v% CaCl ２ ・2H ２ O, 0.02w / v% CoCl ２ ・6H ２ O, 0.016w / v% CuSO ４ ・5H ２ O, 0.012w / v% NiCl ３ ・6H ２ O, 0.01w / v% CrCl ３ ・6H ２O dissolved in water), 2 w / v% Proex AP-12 (manufactured by Banshu Seasoning Co., Ltd.), 5 x 10 －６ The culture medium was oil-based, with palm oil, palm kernel oil, or coconut oil (4 w / v%) added in three separate portions. A glycerol stock of AC32 strain was inoculated into a preculture medium and cultured for 20 hours. A 10-L jar fermenter (MD-500 model, manufactured by Marubishi Bioengineering Co., Ltd.) containing 6 L of production medium was inoculated at 1.5 v / v%. The operating conditions were a culture temperature of 30°C, an agitation speed of 400 rpm, and an aeration rate of 1.8 L / min. The pH was controlled between 6.6 and 6.8. 5N sulfuric acid and sodium hydroxide were used to control the pH. Culture was continued for up to 72 hours. The cells were collected by centrifugation, washed with methanol, and then freeze-dried. A 3-hydroxyalkanoic acid polymer was extracted from the dried bacterial cells using chloroform, and then bacterial components were removed from the chloroform solution containing the 3-hydroxyalkanoic acid polymer by filtration. Methanol was added to the filtrate to precipitate the 3-hydroxyalkanoic acid polymer. The supernatant was then removed by centrifugation, and the polymer was dried to obtain a 3-hydroxyalkanoic acid polymer. The resulting 3-hydroxyalkanoic acid polymer (hereinafter sometimes referred to as "P3HB3HH-1") was represented by the aforementioned general formula (I), had a weight-average molecular weight of 590,000, and a ratio of k to p (k / p) of 83.8 / 16.2.

[0044] (Polyester Polymer (A)) [Production Example A-1] A flask equipped with a vacuum pump and an apparatus capable of distilling off generated liquid was charged with 164 g (1.39 mol) of 3-methyl-1,5-pentanediol and 127 g (0.87 mol) of adipic acid (the molar ratio of 3-methyl-1,5-pentanediol to adipic acid was 3-methyl-1,5-pentanediol / adipic acid = 1.6 / 1), and the mixture was heated under a nitrogen atmosphere at normal pressure at 160°C for 3 hours and then at 220°C for 3 hours, while distilling off water. Next, 0.15 g (0.51 mmol; 150 μL) of tetraisopropyl titanate was added, and the mixture was reacted for 3 hours under reduced pressure to 2,000 Pa. Thereafter, the mixture was further reacted for 3 hours under reduced pressure to 80 Pa, yielding a polyester polyol having the target molecular weight. Next, 200.0 g of the obtained polyester polyol and 94.3 g of toluene were added to a 1000 mL four-neck glass flask, and 196.1 g (1.9 mol) of acetic anhydride was added to the solution. Next, 9.7 g (80 mmol) of 4-dimethylaminopyridine dissolved in 97.7 g of toluene was added, and the mixture was stirred at 40°C for 60 minutes to obtain a reaction solution with acetylated terminals. The resulting reaction solution was extracted with toluene and water and purified by distillation to obtain 210.0 g of polyester polymer (A-1).

[0045] <Ratio (molar ratio) of each constituent component of polyester-based polymer> In the production examples, the ratio of each constituent component of the obtained polyester-based polymer was １ The molar ratio was determined by H-NMR measurement. From the spectrum obtained, the molar ratio was derived from the area ratio of the signal at 4.05-4.18 ppm derived from 3-methyl-1,5-pentanediol, the signal at 4.00-4.05 ppm derived from trimethylolpropane, and the signal at 2.02-2.08 ppm derived from adipic acid and / or sebacic acid. (Measurement conditions) Apparatus: 400YH (manufactured by JEOL Ltd.) Solvent: deuterated chloroform (CDCl3) Measurement temperature: 23°C Number of accumulations: 32

[0046] [Production Example A-2] A polyester polymer (A-2) was obtained in the same manner as in Production Example A-1, except that the amounts of 3-methyl-1,5-pentanediol and adipic acid were changed to 149 g (1.26 mol) and 146 g (1.00 mol) respectively (the molar ratio of 3-methyl-1,5-pentanediol / adipic acid was 1.26 / 1).

[0047] [Production Example A-3] A polyester polymer (A-3) was obtained in the same manner as in Production Example A-1, except that the raw material charges were changed to 106 g (0.90 mol) of 3-methyl-1,5-pentanediol, 59 g (0.45 mol) of trimethylolpropane, and 131 g (0.90 mol) of adipic acid (3-methyl-1,5-pentanediol was replaced with a mixture of 3-methyl-1,5-pentanediol / trimethylolpropane in a molar ratio of 2 / 1).

[0048] [Production Example A-4] A polyester polymer (A-4) was obtained in the same manner as in Production Example A-2, except that the raw material charges were changed to 119 g (1.00 mol) of 3-methyl-1,5-pentanediol, 33.5 g (0.25 mol) of trimethylolpropane, and 147 g (1.00 mol) of adipic acid (3-methyl-1,5-pentanediol was replaced with a mixture of 3-methyl-1,5-pentanediol / trimethylolpropane in a molar ratio of 4 / 1).

[0049] [Production Example A-5] A polyester polymer (A-5) was obtained in the same manner as in Production Example A-1, except that 176 g (0.87 mol) of sebacic acid was used instead of adipic acid.

[0050] [Production Example A-6] A polyester polymer (A-6) was obtained in the same manner as in Production Example A-1, except that the raw material charges were changed to 65.6 g (0.56 mol) of 3-methyl-1,5-pentanediol, 133 g (0.91 mol) of adipic acid, and 92.4 g (0.71 mol) of 2-ethylhexanol (the molar ratio of raw material charges was 3-methyl-1,5-pentanediol / adipic acid / 2-ethylhexanol=0.61 / 1 / 0.78), and the terminal modification step was not performed.

[0051]

[0052] [Examples 1 to 12] The polyester polymers (A-1) to (A-6) obtained in Production Examples A-1 to A-6 and the 3-hydroxyalkanoic acid polymer (P3HB3HH-1) obtained in Production Example I were each charged into a twin-screw kneader (manufactured by Technovel Co., Ltd., product name "ULTnano 50") in the formulations shown in Table 2, extruded into strands at a cylinder temperature of 170°C, a screw rotation speed of 50 rpm, and a residence time of 1 minute, and the resulting strands were cut into pellets to obtain resin compositions. The resulting resin compositions were evaluated as described above. The results are shown in Table 2.

[0053] Comparative Example 1 A resin composition was obtained in the same manner as in Example 1, except that the polyester polymer (A-1) was not used. The obtained resin composition was evaluated as described above. The results are shown in Table 2.

[0054]

[0055] Comparison of Examples 1 to 12 with Comparative Example 1 reveals that the resin compositions obtained in the Examples are excellent in impact resistance, particularly at temperatures below 0°C.

Claims

1. A resin composition comprising a 3-hydroxyalkanoic acid polymer represented by the following formula (I) and a polyester polymer: (In formula (I), the ratio of k to p (k / p) is 70 / 30 to 99 / 1.) The polyester polymer is composed of monomer units consisting only of a polyhydric alcohol component and a dicarboxylic acid component, and at least a portion of the ends of the polyester polymer are blocked with a residue of a monoalcohol and / or a residue of a monocarboxylic acid, the polyhydric alcohol of the polyhydric alcohol component is MPD (3-methyl-1,5-pentanediol) and / or TMP (trimethylolpropane), the dicarboxylic acid of the dicarboxylic acid component is adipic acid or sebacic acid, the monoalcohol is 2-ethylhexanol, and the monocarboxylic acid is acetic acid.

2. The resin composition according to claim 1, which contains 5 to 30 parts by mass of the polyester polymer per 100 parts by mass of the 3-hydroxyalkanoic acid polymer.

3. The resin composition according to claim 1 or 2, wherein the weight average molecular weight of the 3-hydroxyalkanoic acid polymer is 50,000 to 3,000,000.

4. The resin composition according to any one of claims 1 to 3, wherein the ratio of the molar amount of MPD to the total amount of the molar amounts of MPD and TMP contained in the polyester polymer is 0.20 to 1.00, and the ratio of the molar amount of TMP to the total amount of the molar amounts of MPD and TMP is 0 to 0.

80.

5. A resin composition according to any one of claims 1 to 4, wherein the polyester polymer has a hydroxyl value of 20 mgKOH / g or less and an acid value of 15 mgKOH / g or less.

6. The resin composition according to any one of claims 1 to 5, wherein the polyester polymer has a number average molecular weight of 300 to 4,000.

7. A resin composition according to any one of claims 1 to 6, wherein the polyhydric alcohol contained in the polyester polymer is the MPD and the TMP.

8. A resin composition according to any one of claims 1 to 6, wherein the polyhydric alcohol contained in the polyester polymer is the MPD.

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