Resin composition and molded article

Abstract

The present invention relates to a novel resin composition containing poly(3-hydroxybutyrate) (also referred to as "PHB") and a crystallization nucleating agent, the resin composition being capable of suppressing the occurrence of burrs and warpage during injection molding. The resin composition contains PHB, a polyglycerol unsaturated fatty acid ester, and a crystallization nucleating agent.

Description

Resin composition and molded article

[0001] The present invention relates to a resin composition containing poly(3-hydroxybutyric acid) and a molded article thereof.

[0002] Poly(3-hydroxybutyric acid) (also referred to as "PHB") is known as a "marine biodegradable plastic" that exhibits biodegradability even in the ocean among "biodegradable plastics" that are finally completely decomposed into water and carbon dioxide by the action of microorganisms.

[0003] PHB is a polyester composed of 3-hydroxybutyric acid (a ketone body), which is produced from bacteria living in the sea or lakes, and is known to be accumulated as granules in the cytoplasm as an energy substrate in the bacteria. For example, in addition to rhizobia such as the genus Sinorhizobium, it can be produced relatively easily and in large quantities by various bacteria such as the genus Alcaligenes, the genus Athiorhodium, the genus Azotobacter, the genus Bacillus, the genus Nocardia, the genus Pseudomonas, the genus Rhizobium, and the genus Spirillum.

[0004] As described above, PHB has characteristics such as biodegradability and biocompatibility, and also has characteristics different from those of conventional biodegradable plastics, such as being insoluble in water, having hydrolysis resistance, and being vulnerable to moisture. In addition, while many biodegradable resins are effectively decomposed only under aerobic conditions, PHB has the characteristic of being rapidly decomposed even under anaerobic conditions such as the bottom mud of lakes and marshes. Therefore, the use of PHB for various molded articles has been studied. However, since PHB has a slow crystallization rate, it has been an obstacle in the industrial production of various molded articles. Therefore, conventionally, methods of adding a crystallization accelerator (also referred to as a "crystallization nucleating agent") to PHB to improve the crystallization rate and crystallinity have been studied.

[0005] For example, Patent Document 1 discloses a biodegradable, low-warpage molding material characterized by being obtained by melt-mixing PHB, polylactic acid, an inorganic filler, and a crystal nucleating agent. Patent Document 2 discloses a biodegradable polyester resin composition obtained by mixing PHB with a crystal nucleating agent consisting of one or more selected from polyvinyl alcohol, chitin, and chitosan. Patent Document 3 discloses adding pentaerythritol as a nucleating agent to PHB to improve the crystallization rate and thus the molding process speed, as well as miniaturizing the crystals and suppressing changes in the mechanical properties of the molded product over time. Patent Document 4 discloses culturing a predetermined microorganism in the presence of alcohol and using polyhydroxyalkanoic acid, which has a low weight-average molecular weight of 5,000 to 40,000 and is modified with a C1-6 alkyl ester at the carboxyl group terminus, as a crystal nucleating agent.

[0006] Japanese Patent Publication No. 2000-239508, Japanese Patent Publication No. 2007-77232, Japanese Patent Publication No. 2017-101256, Japanese Patent Publication No. 2015-29484

[0007] As described above, even if the crystallization rate can be accelerated by adding a crystallization nucleating agent to PHB, problems remain, such as the nucleating agent getting into the gaps between molds during injection molding, causing burrs, or the crystallization progressing after removal from the mold, resulting in warping. Therefore, the object of the present invention is to provide a new resin composition and a molded article thereof that contains PHB and a crystallization nucleating agent, and that can suppress the generation of burrs and warping during injection molding.

[0008] To solve these problems, the present invention proposes the following embodiments.

[0009] [1] A first aspect of the present invention is a resin composition comprising poly(3-hydroxybutyric acid) (also referred to as "PHB"), a polyglycerol unsaturated fatty acid ester, and a crystal nucleating agent. [2] A second aspect of the present invention is a resin composition according to the first aspect, wherein the unsaturated fatty acid ester constituting the polyglycerol unsaturated fatty acid ester is at least one of oleic acid, ricinoleic acid, and polyricinoleic acid.

[0010] [3] A third aspect of the present invention is a resin composition according to the first or second aspect, comprising 0.5 to 10 parts by mass of the polyglycerin unsaturated fatty acid ester per 100 parts by mass of PHB.

[0011] [4] A fourth aspect of the present invention is a resin composition according to any one of the first to third aspects, comprising 0.01 to 5 parts by mass of the crystal nucleating agent per 100 parts by mass of PHB. [5] A fifth aspect of the present invention is a resin composition according to any one of the first to fourth aspects, comprising 1 to 30 parts by mass of polylactic acid per 100 parts by mass of PHB.

[0012] [6] A sixth aspect of the present invention is a molded article of a resin composition according to any one of the first to fifth aspects.

[0013] The resin composition proposed by the present invention further contains polyglycerol unsaturated fatty acid esters in addition to PHB and a crystal nucleating agent, thereby suppressing the generation of burrs and warping when, for example, injection molding is performed.

[0014] An example of an embodiment of the present invention will be described below. However, the present invention is not limited to the embodiment described below.

[0015] <Resin Composition of the Present Invention> A resin composition according to an example of an embodiment of the present invention (hereinafter referred to as "the resin composition of the present invention") is a resin composition comprising poly(3-hydroxybutyric acid) (PHB), polyglycerin unsaturated fatty acid ester, and a crystal nucleating agent.

[0016] (PHB) The method of manufacturing and obtaining PHB is optional. It can be manufactured by known methods, or commercially available PHB can be used.

[0017] One method for producing PHB is a fermentation synthesis method in which microorganisms capable of producing PHB are cultured and the PHB accumulated within the microbial cells is recovered. By this method, poly(3-hydroxybutyric acid) homopolymer can be obtained. Examples of microorganisms capable of producing PHB, i.e., PHB-producing bacteria, include Bacillus megaterium, as well as Cupriavidus necator (formerly classified as Alcaligenes eutrophus, Ralstonia eutropha), and Alcaligenes latus. Among these, strains of the Methylobacterium genus, specifically Methylobacterium extorquens ATCC55366, can be cited as producing high molecular weight PHB with a mass-average molecular weight of 1 million (number-average molecular weight of 500,000) or more (Bourque, D. et al., Appl. Microbiol.). Biotechnol (1995)).

[0018] In the aforementioned fermentation synthesis method, PHB can usually be accumulated within the cells of these microorganisms by culturing them in a conventional culture medium containing a carbon source, a nitrogen source, inorganic ions, and other organic components as needed. Methods for recovering PHB from the cells include extraction with an organic solvent such as chloroform, and a method of decomposing the cell components with an enzyme such as lysozyme and then filtering off the PHB granules. Another aspect of the fermentation synthesis method is to culture microorganisms transformed by introducing recombinant DNA containing a PHB synthesis gene, and then collect the PHB produced within the cells. In this method, unlike the direct culture of Ralstonia eutropha, the microorganisms transformed by introducing recombinant DNA do not possess PHB-degrading enzymes within their cells, thus enabling the accumulation of significantly higher molecular weight PHB.

[0019] Alternatively, PHB produced by chemical synthesis may be used instead of the fermentation method described above.

[0020] The mass-average molecular weight (Mw) of PHB is not particularly limited as long as it does not interfere with molding, but it is preferably between 50,000 and 3,000,000. If the mass-average molecular weight (Mw) of PHB is 50,000 or more, the strength after molding can be maintained. From this viewpoint, the mass-average molecular weight (Mw) of PHB is preferably 50,000 or more, more preferably 100,000 or more, more preferably 150,000 or more, and more preferably 200,000 or more. On the other hand, the upper limit of the mass-average molecular weight (Mw) of PHB is not particularly limited. Usually, it can be assumed to be 3,000,000 or less. The mass-average molecular weight here can be the one measured from the polystyrene-equivalent molecular weight distribution using gel permeation chromatography (GPC) with chloroform eluent.

[0021] In the resin composition of the present invention, PHB is the main component resin, that is, the resin with the highest mass percentage among the resins constituting the resin composition of the present invention. In this invention, "resin" refers to an organic substance with a mass-average molecular weight of 10,000 or more. The PHB content in the resin composition of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more.

[0022] (Nurturing agent) The resin composition of the present invention may optionally further contain a nucleating agent (also simply referred to as "nucleating agent"). By including a nucleating agent in the resin composition of the present invention, the crystallization of the resin can be promoted or improved, the crystallization rate of the resin composition of the present invention can be further increased, and the crystallinity can be improved.

[0023] Examples of nucleating agents include inorganic substances such as boron nitride, titanium dioxide, talc, layered silicates, calcium carbonate, sodium chloride, and metal phosphates, as well as polyvinyl alcohol, chitin, chitosan, polyethylene oxide, aliphatic carboxylic acid amides, aliphatic carboxylic acid salts, aliphatic alcohols, aliphatic carboxylic acid esters, dimethyl adipate, dibutyl adipate, diisodecyl adipate, and dibutyl sebacate, erythritol, galactitol, mannitol, and arabitol, pentaerythritol, melamine cyanurate, and cellulose. However, the list is not limited to these.

[0024] The nucleating agent is preferably blended in a ratio of 0.01 to 5 parts by mass per 100 parts by mass of PHB. A blending amount of 0.01 parts by mass or more per 100 parts by mass of PHB is preferable because it increases the crystallization rate and improves moldability. From this viewpoint, the blending amount of nucleating agent is preferably 0.01 parts by mass or more per 100 parts by mass of PHB, more preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more. On the other hand, a blending amount of 5 parts by mass or less per 100 parts by mass of PHB is preferable because it allows the nucleating agent to exert its effect without impairing the smoothness of the molded surface. From this viewpoint, the blending amount of nucleating agent is preferably 5 parts by mass or less per 100 parts by mass of PHB, more preferably 4 parts by mass or less, and more preferably 3 parts by mass or less.

[0025] (Polyglycerin unsaturated fatty acid ester) The resin composition of the present invention can be plasticized without reducing the crystallization rate by further containing polyglycerin unsaturated fatty acid ester. In addition, it can suppress the generation of burrs and warping when, for example, injection molding is performed.

[0026] Polyglycerol unsaturated fatty acid esters can be any ester of polyglycerol and an unsaturated fatty acid. The unsaturated fatty acid constituting the above polyglycerol unsaturated fatty acid ester is not particularly limited as long as it is a fatty acid that contains a double bond in the bond between carbon atoms. Examples include palmitoleic acid, oleic acid, elaidic acid, linoleic acid, γ-linolenic acid, α-linolenic acid, arachidonic acid, ricinoleic acid, condensed ricinoleic acid, etc. Among these, it is preferable that it be one of oleic acid, ricinoleic acid, and polyricinoleic acid, from the viewpoint of suppressing the generation of burrs and warping when injection molding.

[0027] Examples of polyglycerol unsaturated fatty acid esters include polyglycerol oleate (polyglyceryl oleate), polyglycerol ricinoleate, and polyglycerol condensed ricinoleate.

[0028] There are no particular restrictions on the average degree of polymerization of the polyglycerin constituting the above-mentioned polyglycerin unsaturated fatty acid ester, but examples include those with an average degree of polymerization of 2 to 10, specifically diglycerin (average degree of polymerization 2), triglycerin (average degree of polymerization 3), tetraglycerin (average degree of polymerization 4), hexaglycerin (average degree of polymerization 6), octaglycerin (average degree of polymerization 8), or decaglycerin (average degree of polymerization 10).

[0029] The HLB value of the polyglycerin unsaturated fatty acid ester is preferably 3 to 9, and more preferably 6 or higher or 8 or lower. Having the HLB value of the polyglycerin unsaturated fatty acid ester within this range provides a favorable balance between lipophilicity and hydrophilicity in the resin composition.

[0030] It is preferable to blend polyglycerin unsaturated fatty acid ester in a ratio of 0.5 to 10 parts by mass per 100 parts by mass of PHB. A blending amount of polyglycerin unsaturated fatty acid ester of 0.5 parts by mass or more per 100 parts by mass of PHB is preferable because it can suppress the occurrence of burrs and warping. From this viewpoint, it is preferable that the blending amount of polyglycerin unsaturated fatty acid ester be 0.5 parts by mass or more per 100 parts by mass of PHB, more preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and more preferably 2 parts by mass or more. On the other hand, it is preferable that the blending amount of polyglycerin unsaturated fatty acid ester be 10 parts by mass or less per 100 parts by mass of PHB because it can suppress bleed-out. From this viewpoint, it is preferable that the blending amount of polyglycerin unsaturated fatty acid ester be 10 parts by mass or less per 100 parts by mass of PHB, more preferably 7 parts by mass or less, and more preferably 5 parts by mass or less.

[0031] (Biodegradable Resin) The resin composition of the present invention may further contain a biodegradable resin as needed. Examples of such biodegradable resins include polylactic acid, polycaprolactone, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polyethylene succinate, polyvinyl alcohol, polyglycolic acid, unmodified starch, modified starch, cellulose acetate, chitosan, etc. However, it is not limited to these. These may be used individually or in combination of two or more. Among these, polylactic acid (PLA) is preferred from the viewpoint of having high biodegradability and being readily available.

[0032] [PLA] Polylactic acid (PLA) can be any polyester having lactic acid as a constituent monomer. For example, a homopolymer of D-lactic acid or L-lactic acid, or copolymers thereof, can be cited. More specifically, it can be any of the following: poly(D-lactic acid) whose structural unit is D-lactic acid, poly(L-lactic acid) whose structural unit is L-lactic acid, and poly(DL-lactic acid) which is a copolymer of L-lactic acid and D-lactic acid, or a mixed resin thereof. It may also be a mixed resin of multiple copolymers having different copolymerization ratios of D-lactic acid and L-lactic acid.

[0033] The copolymer of L-lactic acid and D-lactic acid described above has a copolymerization ratio of D-lactic acid to L-lactic acid (hereinafter abbreviated as "D / L ratio") preferably of "3 / 97" to "15 / 85" or "85 / 15" to "97 / 3", more preferably of "5 / 95" to "15 / 85" or "85 / 15" to "95 / 5", even more preferably of "8 / 92" to "15 / 85" or "85 / 15" to "92 / 8", and particularly preferably of "10 / 90" to "15 / 85" or "85 / 15" to "90 / 10". It is also possible to blend polylactic acids with different D / L ratios, and blending is more preferable because it makes it easier to adjust the D / L ratio of the polylactic acid. In this case, the average value of the D / L ratios of multiple lactic acid polymers should fall within the above range. By blending two or more polylactic acids with different D / L ratios to adjust their crystallinity, it is possible to achieve a balance between heat resistance and thermal shrinkage properties, depending on the intended use.

[0034] Furthermore, as long as the essential properties of PLA are not impaired, a small amount of copolymerizing component may be copolymerized. Examples of such copolymerizing component include at least one selected from the group consisting of α-hydroxycarboxylic acids other than lactic acid, nonaliphatic dicarboxylic acids such as terephthalic acid, aliphatic dicarboxylic acids such as succinic acid, nonaliphatic diols such as ethylene oxide adducts of bisphenol A, and aliphatic diols such as ethylene glycol.

[0035] The mass-average molecular weight of PLA is preferable if the mass-average molecular weight of the polylactic acid resin is 20,000 or more, as this allows for appropriate resin cohesive force and maintains the film's elongation strength. On the other hand, if the mass-average molecular weight is 400,000 or less, the melt viscosity can be reduced, which is preferable from the viewpoint of manufacturing and productivity improvement. From this viewpoint, the mass-average molecular weight of PLA is preferably 20,000 or more, more preferably 40,000 or more, and more preferably 60,000 or more. On the other hand, it is preferable that it be 400,000 or less, more preferably 350,000 or less, and more preferably 300,000 or less.

[0036] It is preferable to blend PLA in a ratio of 1 to 30 parts by mass per 100 parts by mass of PHB. A blending amount of PLA of 1 part by mass or more per 100 parts by mass of PHB is preferable because it makes the resin composition easier to crystallize and easier to mold. From this viewpoint, it is preferable that the blending amount of PLA be 1 part by mass or more per 100 parts by mass of PHB, more preferably 4 parts by mass or more, and more preferably 6 parts by mass or more. On the other hand, it is preferable that the blending amount of PLA be 30 parts by mass or less per 100 parts by mass of PHB because it does not reduce the compatibility of the resin composition and maintains excellent moldability. From this viewpoint, it is preferable that the blending amount of PLA be 30 parts by mass or less per 100 parts by mass of PHB, more preferably 20 parts by mass or less, more preferably 10 parts by mass or less, more preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and more preferably 6 parts by mass or less.

[0037] (Other Components) The resin composition of the present invention may further contain various additives. The amount of these components added is not particularly limited as long as it does not impair the properties of the PHB molded product. Examples include plasticizers, lubricants, inorganic fillers, antioxidants, ultraviolet absorbers, colorants such as dyes and pigments, and antistatic agents. However, it is not limited to these.

[0038] <Use> Since the resin composition of the present invention contains PHB as the main component resin, it has biodegradability, biocompatibility, and hydrolysis resistance. In addition, it has the characteristic of being rapidly decomposed even under anaerobic conditions such as the bottom mud of lakes and marshes. Moreover, since the resin composition of the present invention can be plasticized without reducing the crystallization rate, various molded products can be industrially manufactured. Among them, the resin composition of the present invention is suitable as a raw material for molded products, especially injection molded products, because it can suppress the generation of burrs and warpage when injection molded, for example.

[0039] <Molded Product of the Present Invention> A molded product according to an example of an embodiment of the present invention (referred to as "the molded product of the present invention") is a molded product manufactured using the resin composition of the present invention as a raw material.

[0040] For example, the resin composition of the present invention is melt-kneaded using an extruder, kneader, Banbury mixer, roll, etc., extruded into strands and then cut to obtain pellets made of the resin composition of the present invention in particle shapes such as cylindrical, elliptical columnar, spherical, cubic, rectangular parallelepiped, etc. After sufficiently drying the pellets to remove moisture, they can be molded by a known molding method to obtain any molded product. At this time, examples of the molding method include film molding, sheet molding, injection molding, blow molding, extrusion foaming, bead foaming, etc.

[0041] As the injection molding method, for example, injection molding methods generally employed when molding thermoplastic resins, such as the injection molding method, gas assist molding method, injection compression molding method, etc., can be adopted. In addition, according to other purposes, in-mold molding method, gas press molding method, two-color molding method, sandwich molding method, PUSH-PULL, SCO-RIM, etc. can also be adopted other than the above methods. The molding temperature during injection molding is preferably 140 to 190 °C, and the mold temperature is preferably 20 to 80 °C, more preferably 30 to 70 °C.

[0042] Since the molded product of the present invention is excellent in biodegradability, it can be used, for example, for tableware, agricultural materials, OA parts, household electric appliance parts, automobile members, daily sundries, stationery, various bottle molded products, etc. However, it is not limited to these applications.

[0043] <Explanation of terms, etc.> In the present invention, when described as "α to β" (α and β are arbitrary numbers), unless otherwise specified, it includes the meaning of "α or more and β or less" and also the meaning of "preferably larger than α" or "preferably smaller than β". Further, when described as "α or more" (α is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably larger than α", and when described as "β or less" (β is an arbitrary number), unless otherwise specified, it also includes the meaning of "preferably smaller than β".

[0044] Hereinafter, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described below.

[0045] <Method for measuring physical property values and evaluation method> First, the method for measuring each physical property value shown in the examples and comparative examples, and the evaluation method will be described.

[0046] (Mass average molecular weight) The mass average molecular weight was determined as the molecular weight in terms of polystyrene using gel permeation chromatography ("HLC-8320GPC" manufactured by Tosoh Bioscience, LLC), using two styrene divinylbenzene columns ("TSKgel GMHH-R" manufactured by Tosoh Bioscience, LLC), chloroform as the mobile phase. At this time, the calibration curve was created using polystyrene with mass average molecular weights of 5,430, 37,900, 225,000, 812,000, 3,480,000, 9,760,000, and 20,600,000.

[0047] (Mold release property) The mold release property was evaluated in two steps based on the ease of removing the molded product from the injection mold. 〇 (Pass): The molded product could be removed from the injection mold without using a jig. × (Fail): The molded product could be removed from the injection mold by using a jig.

[0048] (Burrs) Burrs were evaluated to determine whether or not burrs were generated during injection molding, resulting from the shape of the mold. ○ (Pass): No burrs were present at all. △ (Fail): A small amount of burrs, about a few mm in size, was observed. × (Fail): Obvious burrs were observed.

[0049] (Warpage) Warpage was evaluated based on the warpage of the molded product after it was removed from the injection molding die. ○ (Pass): No warpage was detected at all. △ (Fail): No warpage was detected visually, but warpage was detected when the product was placed on a flat surface. × (Fail): Clear warpage was observed visually.

[0050] (Examples 1-2 and Comparative Example 1) The following raw materials were put into a melt extruder (MC15M, manufactured by Xplore Instruments) in the mass ratios shown in the table below, melted and kneaded at 175-180°C for 10 minutes, and then injection molded using an injection molding machine (IM12M, manufactured by the same company) under the conditions of a cylinder temperature of 175-180°C and a mold temperature of 55°C to produce dumbbell pieces (molded products) with a length of 50 mm and a thickness of 2 mm.

[0051] • PHB (Mw: 510,000) • Nucleating agent (talc, "FG-20" manufactured by Nippon Talc Co., Ltd., average particle size 2.0 μm, specific surface area 15 m²) 2 / g) Polyglycerin unsaturated fatty acid ester (polyglycerin oleate ester (polyglyceryl oleate), manufactured by Taiyo Kagaku Co., Ltd. "Tirabazole VR-01", degree of polymerization 10)

[0052]

[0053] (Discussion) The composition of Comparative Example 1, in which only talc was added to PHB as a crystal nucleating agent, produced burrs during molding. In contrast, Examples 1 and 2, in which PHB was blended with a crystal nucleating agent and polyglycerin oleate (polyglyceryl oleate), showed good release properties and improved burr formation. In particular, it was found that sufficient effects could be achieved by blending 1 part by mass or more of polyglycerin oleate (polyglyceryl oleate) per 100 parts by mass of PHB.

[0054] (Examples 1, 3-5 and Comparative Examples 2-3) Dumbbell pieces were prepared in the same manner as described above.

[0055] • PHB (Mw: 510,000) • Nucleating agent (talc, "FG-20" manufactured by Nippon Talc Co., Ltd., average particle size 2.0 μm, specific surface area 15 m²) ２ / g) • Polyglycerin unsaturated fatty acid ester (polyglycerin oleate ester (polyglyceryl oleate), manufactured by Taiyo Kagaku Co., Ltd. "Tirabazole VR-01", degree of polymerization 10) • Polyglycerin unsaturated fatty acid ester (polyglycerin decaoleate ester (polyglyceryl oleate), manufactured by Sakamoto Pharmaceutical Co., Ltd. "SY Glister DAO-7S", degree of polymerization 10) • Polyglycerin unsaturated fatty acid ester (polyglycerin pentaoleate ester (polyglyceryl oleate), manufactured by Sakamoto Pharmaceutical Co., Ltd. "SY Glister PO-3S", degree of polymerization 4) • Polyglycerin unsaturated fatty acid ester (polyglycerin pentaoleate ester (polyglyceryl oleate), manufactured by Sakamoto Pharmaceutical Co., Ltd. "SY Glister PO-5S", degree of polymerization 5) • Fatty acid ester (isobutyl oleate, degree of polymerization 1) • Fatty acid ester (glyceryl stearate, degree of polymerization 1)

[0056]

[0057] (Discussion) Compositions containing isobutyl oleate or glyceryl stearate (Comparative Examples 2 and 3) generated burrs during molding. In contrast, compositions containing polyglyceryl oleate, an unsaturated fatty acid polyglyceryl (Examples 1, 3, 4, and 5), did not generate burrs during molding and did not warp.

[0058] (Example 6 and Comparative Example 4) Dumbbell pieces were prepared in the same manner as described above.

[0059] • PHB (Mw: 510,000) • Nucleating agent (melamine cyanurate, Nissan Chemical Corporation "MC-6000", average particle size 2.0 μm) • Polyglycerin unsaturated fatty acid ester (polyglycerin oleate ester (polyglyceryl oleate), Taiyo Kagaku Co., Ltd. "Tirabazole VR-01", degree of polymerization 10) • Polyglycerin saturated fatty acid ester (polyglycerin stearate ester (polyglyceryl stearate), degree of polymerization 2)

[0060]

[0061] (Discussion) In the composition with polyglyceryl ester of stearic acid, a saturated fatty acid (Comparative Example 4), burrs were generated and warping of the molded product was observed. In contrast, in the composition with polyglyceryl ester of oleic acid, an unsaturated fatty acid (Example 6), it was found that molded products without burrs or warping could be produced without reducing the release properties.

[0062] (Examples 7-11) Dumbbell pieces were prepared using the same method as described above.

[0063] • PHB (Mw: 430,000) • Nucleating agent (talc, "D-600" manufactured by Nippon Talc Co., Ltd., average particle size 0.6 μm, specific surface area 24 m²) ２ / g) • Nucleating agent (talc, "D-800" manufactured by Nippon Talc Co., Ltd., average particle size 0.8 μm, specific surface area 21 m²) ２ / g) • Nucleating agent (boron nitride, MARUKA Corporation "AP-100S", average particle size 3.0 μm, specific surface area 50 m²) ２ / g) • Nucleating agent (melamine cyanurate, Nissan Chemical Corporation "MC-6000", average particle size 0.2 μm) • Polyglycerin unsaturated fatty acid ester (polyglycerin pentaoleate (polyglyceryl oleate), Sakamoto Pharmaceutical Co., Ltd. "SY Glister PO-3S", degree of polymerization 4) • Polyglycerin unsaturated fatty acid ester (polyglycerin ricinoleate (polyglyceryl ricinoleate), Sakamoto Pharmaceutical Co., Ltd. "SY Glister CRS-75", degree of polymerization 6) • Polyglycerin unsaturated fatty acid ester (polyglycerin ricinoleate (polyglyceryl ricinoleate), Taiyo Kagaku Co., Ltd. "Tirabazole D-818M", degree of polymerization 6)

[0064]

[0065] (Discussion) It was found that when polyglyceryl ricinoleate is added as an unsaturated fatty acid ester, molded products without burrs and warping can be produced. Although bleed-out is observed when the amount of polyglyceryl ricinoleate added is 4 parts by mass or more per 100 parts by mass of PHB, it does not affect the evaluation results of the desired release properties and burrs, so it can be added in excess, and it is presumed that the desired effect can be obtained even when added up to at least 10 parts by mass.

[0066] (Comparative Example 5 and Examples 12-17) The following raw materials were put into a melt extruder in the mass ratios shown in the table below, and melted and kneaded at 175°C for 10 minutes to produce pellets. The obtained pellets were dried at 120°C for 7 hours, and then injection molded using an injection molding machine (Japan Steel Works, Ltd. "J55") at a cylinder temperature of 260°C, a mold temperature of 60°C, and an injection speed of 100 mm / sec to produce 1.5 mm thick dumbbell pieces (molded products).

[0067] • PHB (Mw: 430,000) • Nucleating agent (talc, "FG-20" manufactured by Nippon Talc Co., Ltd., average particle size 2.0 μm, specific surface area 15 m²) ２ ( / g) • Polyglycerin unsaturated fatty acid ester (polyglycerin oleate ester (polyglyceryl oleate), manufactured by Taiyo Kagaku Co., Ltd. "Tirabazole VR-01", degree of polymerization 10) • PLA (polylactic acid, manufactured by Maeda Kasei Co., Ltd. "LX-175", Mw 170,000, melting point 150-160°C, Tg 55-60°C)

[0068]

[0069] (Discussion) The compositions with added PLA (Examples 12-17) showed equivalent evaluation results to the composition without PLA (Example 15), indicating that adding PLA as needed does not pose a problem to moldability.

Claims

1. A resin composition comprising poly(3-hydroxybutyric acid) (also referred to as "PHB"), polyglycerol unsaturated fatty acid ester, and a crystal nucleating agent.

2. The resin composition according to claim 1, wherein the unsaturated fatty acid ester constituting the polyglycerin unsaturated fatty acid ester is at least one of oleic acid, ricinoleic acid, and polyricinoleic acid.

3. The resin composition according to claim 1, comprising 0.5 to 10 parts by mass of the polyglycerin unsaturated fatty acid ester per 100 parts by mass of the PHB.

4. The resin composition according to claim 1, comprising 0.01 to 5 parts by mass of the crystal nucleating agent per 100 parts by mass of PHB.

5. The resin composition according to claim 1, comprising 1 to 30 parts by mass of polylactic acid per 100 parts by mass of PHB.

6. A molded article of the resin composition according to any one of claims 1 to 5.

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