JP5459111B2 - Resin composition, method for producing the resin composition, and injection-molded body - Google Patents

Description

  The present invention provides a resin composition comprising a poly-3-hydroxybutyrate polymer and / or polylactic acid and polyurethane, which is excellent in impact resistance and exhibits a high crystallization rate, and the resin composition In addition, the present invention relates to an injection-molded product comprising the resin composition.

  Since poly-3-hydroxybutyrate-based polymers and polylactic acid are obtained from plants as raw materials, they have recently attracted attention as materials with little environmental impact. However, poly-3-hydroxybutyrate-based polymers and polylactic acid have problems that the crystallization speed is slow and the molding processability is inferior and the impact resistance is also inferior. The cycle had to be lengthened, and when forming by extrusion, it was necessary to reduce the discharge amount or introduce a large apparatus with a long production line.

  As a method for solving these problems, a method of mixing polycaprolactone or polybutylene succinate resin has been proposed (for example, see Patent Documents 1 and 2).

  In addition, as a method for improving the crystallization speed of poly-3-hydroxybutyrate polymer or polylactic acid and improving the molding processability thereof, a method of adding a plasticizer or a crystal nucleating agent to the pellet has been proposed. 1) A method of adding a plasticizer such as fatty acid, aliphatic ester, aliphatic amide, or fatty acid metal salt (see, for example, Patent Document 3). 2) Adding silicon nitride as a crystal nucleating agent to increase the crystal growth rate. Method (for example, refer to Patent Document 4), 3) A method for increasing the crystal growth rate by adding ammonium chloride as a crystal nucleating agent (for example, refer to Patent Document 5).

JP-A-9-194281 JP 11-323141 A Japanese Patent Laid-Open No. 7-188573 European Published Patent No. 0291024 International Patent Publication No. 91/197559

  However, in the method of mixing the different polymers proposed in Patent Documents 1 and 2, the impact resistance effect is not sufficient. Further, in the method of adding a plasticizer proposed in Patent Document 3, the plasticizer bleeds to the product surface or the plasticizer migrates to other products, particularly to products made of polyvinyl chloride or polystyrene resins. There were problems such as rapid migration of plasticizers and contamination of production lines such as cooling rolls. Furthermore, in the method of adding the crystal nucleating agent proposed in Patent Documents 4 and 5, the crystal nucleating agent is expensive, and there are problems such as impairing the cost performance of the resin composition.

  Therefore, the present invention comprises a poly-3-hydroxybutyrate-based polymer and / or polylactic acid and polyurethane which are excellent in molding processability, productivity of a molded product and excellent in impact resistance because of a high crystallization rate. The present invention provides a resin composition, a method for efficiently producing the resin composition, and an injection-molded article obtained from the resin composition.

  As a result of intensive studies to solve the above problems, the present inventor has shown that a resin composition comprising a poly-3-hydroxybutyrate polymer and / or polylactic acid and polyurethane exhibits excellent molding processability and impact resistance. As a result, the present invention has been completed.

  That is, the present invention relates to a resin composition characterized by comprising 1 to 99% by weight of poly-3-hydroxybutyrate polymer and / or polylactic acid and 99 to 1% by weight of polyurethane.

  The present invention is described in detail below.

  The resin composition of the present invention comprises a poly-3-hydroxybutyrate polymer and / or polylactic acid 1 to 99% by weight and polyurethane 99 to 1% by weight.

  Examples of the poly-3-hydroxybutyrate polymer (hereinafter referred to as a PHB polymer) used in the present invention include other than poly-3-hydroxybutyrate homopolymer and 3-hydroxybutyrate / 3-hydroxybutyrate. Examples of the hydroxyalkanoate other than 3-hydroxybutyrate in the case of the copolymer include 3-hydroxypropionate, 3-hydroxyvalerate, 3-hydroxy Examples include hexanoate, 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxynonanoate, 3-hydroxydecanoate, 3-hydroxyundecanoate, 4-hydroxybutyrate, and hydroxylaurylate. The copolymer is particularly excellent in molding processability Since the resin composition is obtained, hydroxyalkanoate other than the 3-hydroxybutyrate is preferably one that is copolymerized than 25 mol%. In particular, poly-3-hydroxybutyrate homopolymer, 3-hydroxybutyrate / 3-hydroxyvalerate copolymer, and 3-hydroxybutyrate / 4-hydroxybutyrate copolymer are preferable because they are easily available. Moreover, since it becomes a resin composition excellent in molding processability, it is preferable that the PHB polymer is produced in a microorganism. Such a PHB polymer can be obtained as a commercial product. Moreover, as the manufacturing method, it can also obtain by the method currently disclosed by the US Patent 4477654 gazette, the international publication 94/115519 gazette, the US Patent 5502273 gazette, etc., for example. Moreover, as polylactic acid (hereinafter referred to as PLA), a commercially available product can be used without any particular limitation. For example, (trade name) Lacia (manufactured by Mitsui Chemicals, Inc.) is sold as a commercially available product. .

  In the resin composition of the present invention, it is also possible to use a mixture of a PHB polymer and PLA, and the PHB polymer / PLA weight ratio may be used in the range of 100/0 to 0/100. Among them, it is preferable to use only a PHB polymer without mixing PLA because a resin composition with little change in physical properties after molding can be obtained.

  The polyurethane used in the present invention is a high molecular weight compound having a urethane bond, and may be any urethane polymer generally referred to as a thermoplastic polyurethane elastomer, a crosslinkable polyurethane having a three-dimensional network structure, and the like. Since the resin composition is particularly excellent in impact resistance, thermoplastic polyurethane, 2,4- or 2,6-tolylene diisocyanate, m- or p-phenylene diisocyanate, 1-chlorophenylene-2,4- Diisocyanate, 1,5-naphthalene diisocyanate, methylenebisphenylene-4,4′-diisocyanate, m- or p-xylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, 4,4′-methylenebiscyclohexyl diisocyanate, isophorone diisocyanate Ne , It is preferable using method using a mixture of isocyanate compounds such as trimethylhexamethylene diisocyanate, or a crosslinkable polyurethane.

  When a crosslinkable polyurethane is used, the handling property and the production efficiency of the resin composition are excellent. Therefore, a polyol and an isocyanate compound as raw materials for the crosslinkable polyurethane are mixed with a PHB polymer and / or PLA. Then, it is preferable to heat-melt and mix under a shearing force to advance the urethanization reaction to produce a crosslinkable polyurethane to obtain a resin composition. Here, examples of the polyol include one or more polyols selected from polyester polyols, polyether polyols, polycarbonate polyols, castor oil polyols, and saponified EVA (ethylene-vinyl acetate copolymer). It is done. And if the number of functional groups of a polyol is two or more, there will be no limitation in particular. Examples of the isocyanate compound include 2,4- or 2,6-tolylene diisocyanate, m- or p-phenylene diisocyanate, 1-chlorophenylene-2,4-diisocyanate, 1,5-naphthalene diisocyanate, and methylene bisphenylene-4. , 4'-diisocyanate, m- or p-xylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, 4,4'-methylenebiscyclohexyl diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, etc., or 3 amounts thereof , 1,6,11-undecane triisocyanate, lysine ester triisocyanate, 4-isocyanate methyl-1,8-octamethyl diisocyanate Cyanates, or polyfunctional isocyanate such as polyphenyl methane polyisocyanate and the like, one or more of these can be used. In this case, the molar ratio of the isocyanate group in the isocyanate compound to the hydroxyl group in the polyol is preferably in the range of 0.5 to 1.3 because the resin composition is excellent in rigidity and processability.

  The mixing ratio of the PHB polymer and / or PLA and polyurethane in the resin composition of the present invention is 99/1 to 1/99 by weight ratio of (PHB polymer and / or PLA) / polyurethane, preferably 95/5 to 30/70, more preferably 90/10 to 50/50. When the weight ratio of polyurethane is less than 1%, the obtained resin composition is inferior in impact resistance. On the other hand, when it exceeds 99%, the resin composition obtained is inferior in moldability.

  Since the resin composition of the present invention is a resin composition that is particularly excellent in heat resistance and molding processability, the temperature is increased from room temperature to 10 ° C./min with a differential scanning calorimeter (hereinafter referred to as DSC). The crystal melting point observed when heated at a rate is preferably 130 ° C. or higher and 185 ° C. or lower, particularly 140 ° C. or higher and 185 ° C. or lower, more preferably 150 ° C. or higher and 185 ° C. or lower. The crystal melting point in the present invention refers to DSC (trade name DSC-7, manufactured by Perkin Elmer Co., Ltd.), an aluminum pan loaded with 5 mg of sample, and the temperature of the pan is increased from room temperature to 10 ° C./min. It represents the highest temperature among the peak temperatures of the heat flux based on the crystal melting observed when heated at.

  Furthermore, since the resin composition of the present invention becomes a resin composition having a high crystallization rate and excellent molded product production efficiency, the DSC is heated from room temperature to 180 ° C. at a temperature rising rate of 80 ° C./min. After maintaining at 180 ° C. for 1 minute, the crystallization temperature after cooling at a rate of temperature decrease of 10 ° C./min is preferably 100 ° C. or higher and 170 ° C. or lower, particularly preferably 110 ° C. or higher and 165 ° C. or lower, more preferably 120 ° C. or higher and 160 ° C. It is preferable that it is below ℃. The crystallization temperature refers to DSC (manufactured by Perkin Elmer, trade name DSC-7), an aluminum pan loaded with 5 mg of sample, and the pan is heated from room temperature to 180 ° C./min at 180 ° C./min. The sample is heated up to 180 ° C., held at 180 ° C. for 1 minute, then cooled at a rate of temperature drop of 10 ° C./minute, and is the highest of the peak temperatures of the heat flux observed based on the crystallization of the PHB polymer and / or PLA. Represents a high temperature.

  Since the resin composition of the present invention is a resin composition that is particularly excellent in moldability and excellent in mechanical strength when formed into a molded product, the chloroform-dissolved component is obtained by gel permeation chromatography (hereinafter referred to as GPC). The weight average molecular weight (hereinafter referred to as Mw) in terms of polystyrene when measured is preferably 20000 or more and 3000000 or less, and particularly preferably 50000 or more and 1000000 or less. In addition, Mw of the chloroform melt | dissolution component of a resin composition can also be measured by the molecular weight of the melt | dissolution part obtained by melt | dissolving a molding in 60 degreeC chloroform for 2 hours. In addition, the measurement of Mw in the present invention uses a GPC apparatus (manufactured by Tosoh Corporation, trade name HLC8020GPC) equipped with two columns (trade name TSKgel GMHHR-H, manufactured by Tosoh Corporation) and measuring solvent: chloroform. Using a standard polystyrene (manufactured by Tosoh Corporation), the column elution volume was measured at a measurement temperature of 40 ° C., a sample dissolution condition: 60 ° C., and a sample prepared at a measurement concentration of 50 mg / 50 mL in 2 hours with an injection volume of 100 μL. This was calibrated.

  Examples of the shape of the resin composition of the present invention include a pellet shape, a powder shape, a lump shape, and the like. Among them, the pellets are excellent in production efficiency at the time of manufacture and excellent in handleability at the time of molding. The shape is preferred. As a method for forming a pellet shape, for example, a strand cutting method in which a strand-shaped molten granule is cut with a strand cutter, an underwater cutting method in which a molten resin is cut in water, or the molten resin is cooled or cut by mist or the like. Examples include the hot-cut method and the sheet pelletizing method in which a sheet-shaped molten granule is cut with a sheet pelletizer. Among them, strand cutting is particularly possible because pellets with good resin bite can be obtained during injection molding and extrusion molding. Method, underwater cut method and hot cut method are preferably used.

  As the method for producing the resin composition of the present invention, PHB polymer and / or PLA and polyurethane, or PHB polymer and / or PLA and polyol and isocyanate compound are mixed, kneaded, heated and melted and mixed under shear force. Any method and apparatus may be used if possible, and among them, a resin composition having particularly good production efficiency and excellent molding processability is obtained. Therefore, the temperature of the molten resin discharged from the die of the extruder is 160 ° C. It is preferable to produce using a kneader whose temperature is set to 185 ° C. or lower. Examples of the kneader include a different-direction twin-screw extruder such as a same-direction twin-screw extruder and a conical twin-screw extruder; a batch mixer such as a Banbury mixer and a pressure kneader, and a roll kneader.

  When the resin composition of the present invention is produced, it is desirable to dry the PHB polymer and / or PLA in advance, and the drying conditions are arbitrary, for example, at a temperature of 40 to 90 ° C. for 30 minutes. It is preferable to dry for about 3 days. Further, when molding the resin composition of the present invention, it is desirable to dry the resin composition in advance, and the drying conditions are arbitrary, for example, at a temperature of 40 to 90 ° C. for 30 minutes to It is preferable to dry for about 3 days.

  The molding method of the resin composition of the present invention is arbitrary, and examples thereof include profile extrusion, film, sheet, blow, injection, foaming, extrusion coating, rotational molding, etc. Among them, the injection molding property is excellent. In the case of performing injection molding, if the temperature of the molten resin is 230 ° C. or lower, preferably 210 ° C. or lower, the time required for crystallization in the mold is small, and the molding cycle can be shortened.

  Examples of the resin composition of the present invention include calcium carbonate, mica, talc, silica, barium sulfate, calcium sulfate, kaolin, clay, pyroferrite, bentonite, sericite, zeolite, nepheline cinnite, attapulgite, wollastonite, ferrite, Inorganic fillers such as calcium silicate, magnesium carbonate, dolomite, antimony trioxide, titanium oxide, iron oxide, molybdenum disulfide, graphite, gypsum, glass beads, glass powder, glass balloon, glass fiber, quartz, quartz glass, montmorillonite Various kinds of plant fibers such as starch, cellulose fiber and kenaf; natural fillers such as wood flour, okara, fir shell, bran and organic fillers such as modified products thereof may be mixed. In particular, calcium carbonate and talc also have a function of increasing the crystallization speed, so it is desirable to add them. When a filler is added, the resin composition has an excellent balance between rigidity and impact resistance. Therefore, the filler is preferably used in an amount of 150 parts by weight or less with respect to 100 parts by weight of the resin composition of the present invention.

  Furthermore, it is also possible to add plasticizers such as fatty acids, aliphatic esters, aliphatic amides, and fatty acid metal salts to the resin composition of the present invention.

  In addition, the resin composition of the present invention may contain a crystal nucleating agent as necessary, which further increases the crystal growth rate. Examples of the crystal nucleating agent include nitrided nectar, mica, talc, alumina, calcium hydroxyapatite, and aluminum chloride. Among these, talc and silicon nitride are preferable. Further, it may contain a plasticizer such as fatty acid, aliphatic ester, aliphatic amide, fatty acid metal salt, etc., thereby further increasing the crystal growth rate.

  Furthermore, the resin composition of the present invention includes an antihydrolysis agent represented by carbodiimide, an antiblocking agent, a release agent, an antistatic agent, a slip agent, an antifogging agent, a lubricant, a heat resistance stabilizer, an ultraviolet ray, if necessary. Stabilizers, light stabilizers, weathering stabilizers, antifungal agents, rust inhibitors, ion trap agents, foaming agents, flame retardants, flame retardant aids, and the like may be included. Furthermore, other thermoplastic resins and rubbers, particularly thermoplastic resins called biodegradable resins may be blended.

  The resin composition of the present invention is used for the housing and structure of electrical products; automotive exterior parts such as bumpers, rocker moldings, side moldings, and over fenders; automotive interior parts such as carpets, head liners, door trims, sun visors, etc. For example, it is suitably used.

  Since the resin composition of the present invention has a high crystallization rate, it is excellent in molding processability, productivity of a molded product, and excellent in impact resistance.

  Hereinafter, the present invention will be described with reference to examples, but these are illustrative and the present invention is not limited to these examples.

  Various measurements in Examples and Comparative Examples are shown below.

~ Measurement of crystallization temperature ~
The crystal growth rate was measured using a differential scanning calorimeter (manufactured by Perkin Elmer, trade name DSC-7). A 5 mg sample is cut from the pellet and loaded into an aluminum pan. The pan is heated from room temperature to 180 ° C. at a heating rate of 80 ° C./min and held at 180 ° C. for 1 minute. Then, it cooled at the speed | rate of 10 degree-C / min, and measured the highest temperature among the peak temperature of the heat flux based on crystallization as crystallization temperature.

~ Measurement of crystal melting point ~
The crystal melting point was measured using a differential scanning calorimeter (trade name DSC-7, manufactured by Perkin Elmer). A 5 mg sample is cut from the pellet and loaded into an aluminum pan. The highest temperature among the peak temperatures of the heat flux based on crystal melting observed when the pan was heated from room temperature at a heating rate of 10 ° C./min was measured as the crystal melting point.

~ Measurement of weight average molecular weight ~
The molecular weight was measured by gel permeation chromatography using only the dissolved components obtained by dissolving the pellets obtained by granulation in chloroform at 60 ° C. for 2 hours. Calibration was performed using standard polystyrene (manufactured by Tosoh Corporation), and the weight average molecular weight (Mw) was determined in terms of polystyrene. The measurement conditions are shown below.
Model: Product name HLC8020GPC (manufactured by Tosoh Corporation)
Solvent: Chloroform sample dissolution conditions: 60 ° C, 2 hours temperature: 40 ° C
Measurement concentration: 50 mg / 50 mL
Injection volume: 100 μL
Column: Two trade names TSKgel GMHHR-H (manufactured by Tosoh Corporation) -Measurement of solidification time in injection molding-
Injection molding was performed using an injection molding machine (trade name IS100E, manufactured by Toshiba Machine Co., Ltd.), and the solidification time was measured. The set temperature is NH: 180 ° C., H1: 175 ° C., H2: 160 ° C., H3: 140 ° C., mold temperature: 60 ° C., injection pressure: 6.8 MPa, a total of 10 seconds of injection time and compensation time Injection molding was performed under the conditions, and after completion of the pressure-compensating step, the cooling time was increased every other second and an attempt was made to take out the molded product with an ejector pin. The minimum cooling time during which the product can be taken out by ejection with an ejector pin was measured as the minimum solidification time. In addition, the temperature of the molten resin when molding is performed under these conditions is 183 ° C.

~ Measurement of Izod impact strength ~
The Izod impact strength at 23 ° C. was measured using a notched Izod test piece obtained by injection molding.

Example 1
100 parts by weight of a polyester polyol obtained by condensation polymerization of 3-methyl-1,5-pentanediol and adipic acid (manufactured by Kuraray Co., Ltd., trade name Kurapol P2010, number average molecular weight 2000) and hexamethylene diisocyanate as an isocyanate compound Isocyanurate modified form of cyanate (polyfunctional isocyanate compound, average functional group number 3.6 / one molecule) (product name: Coronate HX, manufactured by Nippon Polyurethane Co., Ltd.) 12.9 parts by weight (NCO / OH (isocyanate index)) = 0.65) and DBTDL (dibutyltin dilaurate) 26.7 PPM as a catalyst were mixed together and left in an oven at 120 ° C. for 2 hours to prepare a polyurethane. The obtained polyurethane was made into a ribbon shape with a roll kneader to obtain a composite material.

  A poly-3-hydroxybutyrate polymer (manufactured by PHB Industrial S / A, trade name Biocycle 1000) preliminarily dried in an oven at 80 ° C. for 4 hours in advance and 70:30 (PHB polymer: Polyurethane) by weight extrusion with a bi-directional extruder (trade name: Labo Blast Mill, manufactured by Toyo Seiki Seisakusho; resin temperature 181 ° C., rotational speed 60 rpm) equipped with a circular die. The pellet was obtained by solidifying with a hot tub set at ° C. and pelletizing with a strand cutter.

  Table 1 shows the crystallization temperature, the crystal melting point, the weight average molecular weight of the chloroform-dissolved component, the solidification time in the injection molding, and the Izod impact strength of the obtained pellets.

Example 2
100 parts by weight of poly-3-hydroxybutyrate polymer (trade name Biocycle 1000, manufactured by PHB Industrial S / A) preliminarily dried in an oven at 80 ° C. for 4 hours in a Henschel mixer having an internal volume of 10 liters, and further calcium carbonate As described above, 50 parts by weight of precipitated calcium carbonate whose surface was treated with fatty acid (manufactured by Shiraishi Kogyo Co., Ltd., trade name: white glazed CCR, average particle size: 0.12 μm) was charged and stirred at a rotational speed of 950 rpm for 2 minutes. Separately, 20 parts by weight of a polyester polyol obtained by condensation polymerization of 1,4-butanediol, ethylene glycol and adipic acid (manufactured by Nippon Polyurethane Co., Ltd., trade name: Nipporan 4042, number average molecular weight 2000) is mixed. 3.8 parts by weight of hexamethylene diisocyanate trimer (trade name Coronate HX, manufactured by Nippon Polyurethane Co., Ltd.) (NCO group / OH group ratio = 0.85), and dibutyltin dilaurate as a catalyst 0.015 A part by weight was charged and mixed at room temperature.

  The powder component mixed with the Henschel mixer was put into a Banbury mixer having an internal volume of 1700 cc and a casing temperature of 160 ° C., and stirred at a constant rotational speed. Separately, liquid components mixed at room temperature were added and mixed for 3 minutes. The resin temperature immediately after mixing was 180 ° C. Immediately after the kneading, the obtained composite was put on a roll molding machine to form a sheet and cooled and solidified. Then, it was made into a pellet shape with a sheet pelletizer.

  Table 1 shows the crystallization temperature, the crystal melting point, the weight average molecular weight of the chloroform-dissolved component, the solidification time in the injection molding, and the Izod impact strength of the obtained pellets.

Example 3
100 parts by weight of a poly 3-hydroxybutyrate polymer (manufactured by PHB Industrial S / A, trade name Biocycle 1000), 10 parts by weight of polylactic acid (trade name Lacia H440, manufactured by Mitsui Chemicals), polyester as a thermoplastic polyurethane elastomer 20 parts by weight of polyurethane (manufactured by Nihon Milactolan Co., Ltd., trade name Milactolan P485), 50 parts by weight of talc (manufactured by Fuji Talc, trade name LSM # 300), hexamethylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name HDI) 3 The parts by weight were mixed with a 30 mm twin screw extruder (manufactured by Nippon Steel Works, trade name: TEX30: L / D = 42). The resin temperature was 183 ° C. The extruded strand was solidified in a hot tub set at 60 ° C., and pelletized by pelletizing with a strand cutter.

  Table 1 shows the crystallization temperature, the crystal melting point, the weight average molecular weight of the chloroform-dissolved component, the solidification time in the injection molding, and the Izod impact strength of the obtained pellets.

Comparative Example 1
Pellets were obtained in exactly the same manner as in Example 1, except that extrusion was performed only with a poly-3-hydroxybutyrate polymer (manufactured by PHB Industrial S / A, trade name Biocycle 1000).

  Table 1 shows the crystallization temperature, the crystal melting point, the weight average molecular weight of the chloroform-dissolved component, the solidification time in the injection molding, and the Izod impact strength of the obtained pellets.

  The obtained resin was inferior in Izod impact strength.

Comparative Example 2
Except not using 20 parts by weight of a polyester-based polyurethane (trade name Milactolan P485, manufactured by Nippon Milactolan Co., Ltd.) and 3 parts by weight of hexamethylene diisocyanate (trade name: HDI, manufactured by Nippon Polyurethane Co., Ltd.) as the thermoplastic polyurethane elastomer. In the same manner as in No. 3, pellets were obtained.

  Table 1 shows the crystallization temperature, the crystal melting point, the weight average molecular weight of the chloroform-dissolved component, the solidification time in the injection molding, and the Izod impact strength of the obtained pellets.

  The obtained resin is inferior in Izod impact strength.

Comparative Example 3
Except for extruding only with the polyurethane obtained in Example 1, pellets were obtained in exactly the same manner as in Example 1, but the extrudate was not formed into a strand shape and could not be granulated.

  Since the resin composition of the present invention has a high crystallization rate, it is excellent in molding processability, productivity of molded products and also in impact resistance, and is expected to be developed as various injection molded products. is there.

Claims (5)

Calcium carbonate 40.39 to 150 parts by weight or talc 40.65 to 150 parts by weight with respect to 100 parts by weight of the total amount consisting of 1 to 99% by weight of poly-3-hydroxybutyrate polymer and 99 to 1% by weight of polyurethane A resin composition comprising: The resin composition according to claim 1, wherein the resin composition satisfies the following characteristics (a) and (b).
(A) The crystal melting point observed when heated from room temperature at a heating rate of 10 ° C./min with a differential scanning calorimeter is 130 ° C. or higher and 185 ° C. or lower.
(B) The polystyrene equivalent weight average molecular weight (Mw) when the chloroform-dissolved component is measured by gel permeation chromatography is 20,000 or more and 3000000 or less. The resin composition according to claim 1, wherein the polyurethane forms a three-dimensional network structure. The poly-3-hydroxybutyrate-based polymer is mixed with a polyol and an isocyanate compound, further calcium carbonate or talc, and subjected to urethanization reaction while heating and melting and mixing under a shearing force. The manufacturing method of the resin composition in any one. A molded article obtained by injection molding the resin composition according to any one of claims 1 to 3 at 230 ° C or lower.