Method for producing poly (3-hydroxyalkanoate) - based resin composition for molding

Abstract

To provide a method for producing a poly (3-hydroxyalkanoate) - based resin composition for molding processing, in which crystallization is promoted when the poly (3-hydroxyalkanoate) - based resin composition for molding processing is produced by melt molding under shear flow, and crystallization can also be promoted when the obtained resin composition for molding processing is heated, melted and molded.SOLUTION: The poly (3-hydroxyalkanoate) - based resin composition for molding is produced by melt-molding a poly (3-hydroxyalkanoate) - based resin composition containing a poly (3-hydroxyalkanoate) - based copolymer (A) and a poly (3-hydroxybutyrate) resin (C) under the following shear flow. Shear rate: 10 to 95sec - 1, shear application time: 1 to 1, 200sec, shear application temperature: 100 to 185 °C SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding. [Background technology]

[0002] In recent years, plastic waste has become a burden on the global environment, affecting ecosystems, emitting harmful gases when burned, and contributing to global warming due to the large amount of heat generated by combustion. There has been active development of biodegradable plastics as a material that can solve these problems.

[0003] Among biodegradable plastics, biodegradable plastics produced by microorganisms using plant-derived raw materials as a carbon source, particularly aliphatic polyester resins, have attracted attention from the viewpoints of biodegradability and carbon neutrality. Among these, poly(3-hydroxyalkanoate) resins, such as poly(3-hydroxybutyrate) homopolymer resin, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer resin, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin, and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer resin, have attracted attention.

[0004] Generally, the poly(3-hydroxyalkanoate) resins, particularly copolymer poly(3-hydroxyalkanoate) resins, have a problem in that they have low processability during melt molding due to their slow crystallization rate. With regard to this problem, Patent Document 1 discloses a poly(3-hydroxyalkanoate)-based resin composition containing first and second poly(3-hydroxyalkanoate)-based resins, in which the melting point of the second polyhydroxyalkanoate is observed at a temperature lower than the melting point measured for the second polyhydroxyalkanoate alone.

[0005] Furthermore, Patent Document 2 discloses a polyester resin composition containing polyhydroxyalkanoate and low-melting-point polyhydroxybutyrate, in which the low-melting-point polyhydroxybutyrate has a weight-average molecular weight of 5,000 to 50,000. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2015 / 146194 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-227543 Summary of the Invention [Problem to be solved by the invention]

[0007] Although the compositions described in Patent Documents 1 and 2 can promote the crystallization of poly(3-hydroxyalkanoate) resins, the effect is still insufficient and further improvement is required.

[0008] Actual molding processes are governed by shear flow. When a composition containing a poly(3-hydroxyalkanoate) resin is melt-molded under shear flow to produce, for example, a pellet-shaped resin composition for molding, good crystallization is required. Furthermore, when the obtained resin composition for molding is heated and melted by extrusion molding or injection molding to form a molded article of a desired shape, good crystallization is also required.

[0009] In view of the above-described current situation, the present invention aims to provide a method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding processing, which promotes crystallization when the poly(3-hydroxyalkanoate)-based resin composition for molding processing is produced by melt molding under shear flow, and also promotes crystallization when the resulting resin composition for molding processing is heated, melted, and molded. [Means for solving the problem]

[0010] As a result of intensive research to solve the above-mentioned problems, the inventors have discovered that by melt-molding a resin composition containing a poly(3-hydroxyalkanoate) copolymer and a poly(3-hydroxybutyrate) resin under specific shear flow conditions to produce a poly(3-hydroxyalkanoate) resin composition for molding, crystallization of the resin during production can be promoted, and crystallization can also be promoted when the resulting resin composition for molding is heated, melted, and molded, thereby completing the present invention.

[0011] That is, the present invention relates to a method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding, which comprises a step of melt-molding a poly(3-hydroxyalkanoate)-based resin composition containing a poly(3-hydroxyalkanoate)-based copolymer (A) and a poly(3-hydroxybutyrate) resin (C) under the following shear flow: Shearing rate: 10~95sec -1 , Shear application time: 1 to 1,200 seconds, Shear application temperature: 100 to 185°C [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding, which promotes crystallization when the poly(3-hydroxyalkanoate)-based resin composition for molding is produced by melt molding under shear flow, and also promotes crystallization when the resulting resin composition for molding is heated, melted, and molded. According to the present invention, the crystallization rate during melt molding under shear flow is improved, and therefore a resin composition for molding can be produced stably with good productivity under practical processing conditions.

[0013] In addition, according to a preferred embodiment of the present invention, the torque during kneading can be kept relatively low, thereby suppressing heat generation due to kneading and thermal decomposition of the poly(3-hydroxyalkanoate) resin.

[0014] Furthermore, crystallization can be promoted when the resin composition for molding (e.g., pellets) obtained by the production method of the present invention is heated and melted to be molded into a molded article having a desired shape. In relation to such promotion of crystallization, the resin composition for molding obtained by the production method of the present invention can have a melt memory effect. The melt memory effect refers to a phenomenon in which, when the resin composition for molding is heated and melted, the crystallization history remains even after all the resin crystals contained in the composition have melted and disappeared, thereby promoting the crystallization of the composition. By taking advantage of this effect, it is possible to put into practical use a poly(3-hydroxyalkanoate)-based resin composition for molding that can be molded at high speed.

[0015] According to a preferred embodiment of the present invention, a molded article made from the poly(3-hydroxyalkanoate) resin composition is less likely to produce foreign matter and can exhibit a good appearance.

[0016] According to a preferred embodiment of the present invention, the range of temperature conditions that can be applied during molding, including the process of melting and cooling and solidifying a molding material containing a poly(3-hydroxyalkanoate) resin, is wide, enabling stable molding and producing molded articles with relatively uniform thickness and weight and good appearance. Moreover, productivity can be improved, enabling high-speed mass production of molded articles. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating an example of a polarizing microscope photograph showing the morphology of crystals observed in Examples or Comparative Examples, and an evaluation method thereof. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to this embodiment includes a step of melt-molding a poly(3-hydroxyalkanoate)-based resin composition containing a poly(3-hydroxyalkanoate)-based copolymer (A) and a poly(3-hydroxybutyrate) resin (C) under a specific shear flow. In the present application, the term "resin composition for molding processing" refers to a resin composition, such as pellets, that is used to form a molded article having a desired shape by heating and melting the composition and then cooling and solidifying it.

[0019] In the production method according to the present embodiment, a poly(3-hydroxyalkanoate)-based resin composition containing a poly(3-hydroxyalkanoate)-based copolymer (A) and a poly(3-hydroxybutyrate) resin (C) is used. The resin composition may be a dry blend of the components, or may be a pre-melted mixture of the components.

[0020] <Poly(3-hydroxyalkanoate) copolymer (A)> The poly(3-hydroxyalkanoate) copolymer (A) is a biodegradable aliphatic polyester (preferably a polyester not containing an aromatic ring) having at least one or more types of 3-hydroxyalkanoate units. In the present application, the poly(3-hydroxyalkanoate) copolymer is also referred to as P3HA.

[0021] The 3-hydroxyalkanoate unit is preferably represented by the following general formula (1). [-CHR-CH2-CO-O-] (1)

[0022] In the general formula (1), R is C p H 2p+1where p is an integer of 1 to 15. Examples of R include linear or branched alkyl groups such as methyl, ethyl, propyl, methylpropyl, butyl, isobutyl, t-butyl, pentyl, and hexyl. p is preferably 1 to 10, and more preferably 1 to 8.

[0023] As the poly(3-hydroxyalkanoate) copolymer (A), a poly(3-hydroxyalkanoate) copolymer produced by a microorganism is particularly preferred. In the poly(3-hydroxyalkanoate) copolymer produced by a microorganism, all of the 3-hydroxyalkanoate units are contained as (R)-3-hydroxyalkanoate units.

[0024] The poly(3-hydroxyalkanoate) copolymer (A) preferably contains 3-hydroxyalkanoate units (particularly units represented by general formula (1)) in an amount of 50 mol % or more, more preferably 60 mol % or more, and even more preferably 70 mol % or more of the total structural units (monomer units). The poly(3-hydroxyalkanoate) copolymer may contain only two or more types of 3-hydroxyalkanoate units as structural units of the polymer, or may contain other units (e.g., 4-hydroxyalkanoate units) in addition to one or more types of 3-hydroxyalkanoate units.

[0025] The poly(3-hydroxyalkanoate) copolymer (A) is preferably a copolymer containing 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) units and other hydroxyalkanoate units, and the 3-hydroxybutyrate units are preferably all (R)-3-hydroxybutyrate units.

[0026] The other hydroxyalkanoate units may be 3-hydroxyalkanoate units other than 3HB units, or may be hydroxyalkanoate units other than 3-hydroxyalkanoate units (e.g., 4-hydroxyalkanoate units). Only one type of other hydroxyalkanoate unit may be included, or two or more types may be included.

[0027] Specific examples of the poly(3-hydroxyalkanoate) copolymer (A) include poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviation: P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HH), poly(3- Examples of suitable poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxynonanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-3-hydroxyundecanoate), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviation: P3HB4HB) are listed. In particular, from the viewpoints of productivity and mechanical properties of the resin composition, P3HB3HH or P3HB4HB is preferred, with P3HB3HH being particularly preferred.

[0028] P3HA can be produced by microorganisms. Such microbially produced P3HA is typically P3HA composed solely of D-form (R-form) hydroxyalkanoic acid repeating units. Among microbially produced P3HAs, P3HB3HH, P3HB3HV, P3HB3HV3HH, and P3HB4HB are preferred because of ease of industrial production, with P3HB, P3HB3HH, P3HB3HV, and P3HB4HB being more preferred, and P3HB3HH being particularly preferred. Only one type of P3HA may be used, or two or more types with different monomer species or ratios may be used in combination.

[0029] Microorganisms that produce P3HA are not particularly limited as long as they are capable of producing P3HA. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925. Other known natural microorganisms include Cupriavidus necator (formerly Alcaligenes eutrophus, Ralstonia eutropha) and Alcaligenes latus. These microorganisms accumulate P3HB intracellularly.

[0030] Known microorganisms that produce copolymers of 3HB with other hydroxyalkanoates include Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes eutrophus, which produces P3HB4HB. In particular, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)), which has been transformed with genes encoding P3HA synthases, is preferred for increasing P3HB3HH productivity. Microorganisms such as these, which are cultured under appropriate conditions to accumulate P3HA within the cells, are used. In addition to the above, genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced may be used depending on the P3HA to be produced, or the culture conditions, including the type of substrate, may be optimized.

[0031] The weight-average molecular weight of the poly(3-hydroxyalkanoate) copolymer (A) is not particularly limited, but is preferably in the range of 100,000 to 1,000,000. By setting the weight-average molecular weight of P3HA (A) to 100,000 or more, it becomes easier to form molded articles exhibiting good physical properties. Furthermore, by using it in combination with the poly(3-hydroxybutyrate) resin (C) described below, crystallization after melting the resin composition and applying shear is promoted, allowing for the production of a resin composition for molding with high productivity. On the other hand, by setting the weight-average molecular weight of P3HA (A) to 1,000,000 or less, processability is further improved and molding becomes easier. The weight-average molecular weight of P3HA (A) is preferably 200,000 to 800,000. It may also be greater than 200,000. Furthermore, a range of 250,000 to 700,000 is more preferable, and a range of 300,000 to 600,000 is even more preferable.

[0032] The weight-average molecular weight of the poly(3-hydroxyalkanoate) copolymer (A) can be determined as a polystyrene-equivalent molecular weight using gel permeation chromatography (GPC) (Shimadzu Corporation's "High-Performance Liquid Chromatograph 20A System"), a polystyrene gel column (Showa Denko KG 4A, "K-806M"), and chloroform as the mobile phase. Calibration curves are prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. A column suitable for measuring the molecular weight can be used for the GPC.

[0033] The poly(3-hydroxyalkanoate) copolymer (A) is a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, and the content of the other hydroxyalkanoate units is preferably 1 mol% or more and 23 mol% or less. By keeping the content within this range, the poly(3-hydroxyalkanoate) resin composition can achieve both flexibility and rigidity, and productivity can also be improved. The content is more preferably 1 to 20 mol%, even more preferably 1 to 15 mol%, and particularly preferably 1 to 10 mol%. The lower limit of the content may be 2 mol% or more, or even 3 mol% or more.

[0034] The content of the other hydroxyalkanoate units refers to the molar ratio of each monomer unit to all monomer units constituting P3HA(A). When P3HA(A) is a mixture of two or more P3HAs, the content refers to the molar ratio of each monomer unit contained in the entire mixture. The monomer composition ratio in P3HA can be measured by gas chromatography or the like, and the description in WO 2014 / 020838 can be referenced, for example.

[0035] <Poly(3-hydroxybutyrate) resin (C)> The poly(3-hydroxyalkanoate) resin composition used in this embodiment further contains a poly(3-hydroxybutyrate) resin (C). This resin (C) crystallizes more easily than the poly(3-hydroxyalkanoate) copolymer (A). In addition, the molecular chains of the resin (C) are more likely to orient under melt shear, thereby inducing crystallization. Furthermore, the formation of oriented crystals by the resin (C) allows for the retention of a crystalline history even when heated to 185°C or higher, at which point the resin (C) completely melts. This melt memory effect can promote crystallization of the resin composition. Therefore, the use of this resin (C) promotes crystallization after shear application, enabling the efficient production of a resin composition for molding. Furthermore, crystallization during heating and molding of the resin composition for molding is also promoted, enabling the efficient production of molded articles.

[0036] The poly(3-hydroxybutyrate) resin (C) refers to a homopolymer of 3-hydroxybutyrate or a polymer containing, in addition to 3-hydroxybutyrate units, a small amount of hydroxyalkanoate units other than 3-hydroxybutyrate units. Specifically, the poly(3-hydroxybutyrate) resin (C) preferably contains 3-hydroxybutyrate units in a proportion of more than 99 mol % and not more than 100 mol % of all of its constituent monomers.

[0037] The hydroxyalkanoate units other than 3-hydroxybutyrate units that can be contained in the poly(3-hydroxybutyrate) resin (C) are not particularly limited as long as they are copolymerizable with 3-hydroxybutyrate units, and examples thereof include 3-hydroxyalkanoate units other than 3-hydroxybutyrate units and hydroxyalkanoate units other than 3-hydroxyalkanoate units (e.g., 4-hydroxyalkanoate units). 3-hydroxyhexanoate units are particularly preferred.

[0038] The weight-average molecular weight of the poly(3-hydroxybutyrate) resin (C) is not particularly limited, but is preferably in the range of 10,000 to 1,000,000. By making the weight-average molecular weight of the resin (C) 10,000 or more, the resin is easily oriented under melt shear, thereby inducing crystallization. Therefore, melting and applying shear promotes crystallization, allowing for the production of a resin composition for molding with high productivity. Furthermore, crystallization is also promoted when the resin composition for molding is heated and melted for molding, allowing for the production of molded articles with high productivity. The weight-average molecular weight is more preferably 100,000 or more, even more preferably 160,000 or more, even more preferably 200,000 or more, and particularly preferably 250,000 or more.

[0039] On the other hand, by setting the weight average molecular weight of resin (C) to 1,000,000 or less, foreign matter is less likely to be generated in the molded product, and further, processability is further improved, making molding easier. It is more preferably 900,000 or less, even more preferably 70 or less, still more preferably 500,000 or less, and particularly preferably 400,000 or less. The weight average molecular weight of the resin (C) can be measured in the same manner as the weight average molecular weight of the P3HA (A).

[0040] The amount of poly(3-hydroxybutyrate) resin (C) can be set as appropriate, but is preferably in the range of 0.1 to 50 parts by weight per 100 parts by weight of P3HA (A). By setting the content of resin (C) at 0.1 parts by weight or more, the crystallization-promoting effect and melt memory effect due to the use of resin (C) are easily achieved. It is more preferably 1 part by weight or more, even more preferably 3 parts by weight or more, particularly preferably 5 parts by weight or more, and most preferably more than 5 parts by weight. Furthermore, it is preferably 10 parts by weight or more, more preferably 20 parts by weight or more, even more preferably 30 parts by weight or more, and particularly preferably 40 parts by weight or more.

[0041] On the other hand, by setting the blending amount of resin (C) to 50 parts by weight or less, the torque during kneading can be kept relatively low, and heat generation due to kneading and thermal decomposition of the poly(3-hydroxyalkanoate) resin can be suppressed. It is more preferably 40 parts by weight or less, even more preferably 30 parts by weight or less, still more preferably 20 parts by weight or less, and particularly preferably 15 parts by weight or less.

[0042] The poly(3-hydroxyalkanoate)-based resin composition for molding according to this embodiment is different from the expanded resin particles disclosed in WO 2019 / 146555 or WO 2022 / 054870, and is preferably a non-expanded resin composition that does not substantially contain air bubbles inside.

[0043] The poly(3-hydroxyalkanoate)-based resin composition for molding according to this embodiment is not foamed, and therefore exhibits a relatively high density, which is 0.3 g / cm 3 It is preferable that the density exceeds 0.5 g / cm 3 More preferably, 0.7 g / cm 3 The upper limit is not particularly limited, but for example, 1.6 g / cm 3 may be less than or equal to 1.4 g / cm 3The density of the resin composition can be determined by the method described in JIS K0061 (Method for measuring density and specific gravity of chemical products) or JIS Z8807 (Method for measuring density and specific gravity of solids).

[0044] The poly(3-hydroxyalkanoate)-based resin composition for molding according to this embodiment may contain, in addition to P3HA (A) and poly(3-hydroxybutyrate) resin (C), optionally at least one selected from the group consisting of other resins, crystal nucleating agents, and lubricants.

[0045] <Other resins> The poly(3-hydroxyalkanoate)-based resin composition for molding may contain another resin that does not fall under either P3HA (A) or poly(3-hydroxybutyrate) resin (C). The other resin is not particularly limited, but it is preferable that the other resin does not significantly impair the compatibility or moldability of the poly(3-hydroxyalkanoate)-based resin composition for molding, or the mechanical properties of the resulting molded article when molding the poly(3-hydroxyalkanoate)-based resin composition for molding. Furthermore, when the resulting molded article is to be used in an application requiring biodegradability, the other resin is preferably a biodegradable resin.

[0046] Examples of the other resins include aliphatic polyesters formed by polycondensation of aliphatic diols and aliphatic dicarboxylic acids, and aliphatic-aromatic polyesters containing both aliphatic and aromatic compounds as monomers. Examples of the former include polyethylene succinate, polybutylene succinate (PBS), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (PBSA), polyethylene sebacate, and polybutylene sebacate. Examples of the latter include poly(butylene adipate-co-butylene terephthalate) (PBAT), poly(butylene sebacate-co-butylene terephthalate), poly(butylene azelate-co-butylene terephthalate), and poly(butylene succinate-co-butylene terephthalate) (PBST). The other resins may be used singly or in combination of two or more.

[0047] When the poly(3-hydroxyalkanoate)-based resin composition for molding contains the other resin, the content of the other resin is preferably 250 parts by weight or less, more preferably 100 parts by weight or less, even more preferably 50 parts by weight or less, and particularly preferably 20 parts by weight or less, per 100 parts by weight of the total of P3HA (A) and poly(3-hydroxybutyrate) resin (C). It may also be 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less. There is no particular lower limit for the content of the other resin, and it may even be 0 parts by weight.

[0048] <Nucleating agent> The poly(3-hydroxyalkanoate)-based resin composition for molding may further contain a crystal nucleating agent, which further promotes crystallization of the resin component and can improve molding speed, productivity, etc.

[0049] The crystal nucleating agent is not particularly limited, and conventionally known ones can be used. Examples of the crystal nucleating agent include inorganic substances such as pentaerythritol, boron nitride, titanium oxide, talc, layered silicates, calcium carbonate, sodium chloride, and metal phosphates; sugar alcohol compounds derived from natural products such as erythritol, galactitol, mannitol, and arabitol; polyvinyl alcohol, chitin, chitosan, polyethylene oxide, aliphatic carboxylic acid amides, aliphatic carboxylic acid salts, aliphatic alcohols, aliphatic carboxylic acid esters, dimethyl adipate, Examples of suitable nucleating agents include dicarboxylic acid derivatives such as dibutyl adipate, diisodecyl adipate, and dibutyl sebacate; cyclic compounds such as indigo, quinacridone, and quinacridone magenta, which have a functional group C=O and a functional group selected from NH, S, and O in the molecule; sorbitol derivatives such as bisbenzylidene sorbitol and bis(p-methylbenzylidene) sorbitol; compounds containing a nitrogen-containing heteroaromatic nucleus such as pyridine, triazine, and imidazole; phosphate ester compounds, bisamides of higher fatty acids, and metal salts of higher fatty acids. These nucleating agents may be used alone or in combination of two or more.

[0050] The content of the nucleating agent is not particularly limited as long as it can promote the crystallization of the resin components, but is preferably 0.05 to 12 parts by weight, more preferably 0.1 to 10 parts by weight, and even more preferably 0.5 to 8 parts by weight, per 100 parts by weight of the total of P3HA (A) and poly(3-hydroxybutyrate) resin (C). When the content of the nucleating agent is within the above range, it can be effective as a nucleating agent while suppressing deterioration in viscosity during molding and physical properties of the molded product.

[0051] However, the poly(3-hydroxyalkanoate)-based resin composition for molding may be substantially free of sugar alcohols such as pentaerythritol. "Substantially free of sugar alcohols" means that the amount of sugar alcohols is less than 0.05 parts by weight per 100 parts by weight of the total of P3HA (A) and poly(3-hydroxybutyrate) resin (C). It may also be less than 0.01 parts by weight. In this embodiment, by using poly(3-hydroxybutyrate) resin (C), the productivity of the resin composition or molded article can be improved even without substantially adding sugar alcohols, which serve as crystallization nucleating agents.

[0052] <Lubricant> The poly(3-hydroxyalkanoate)-based resin composition for molding may further contain a lubricant. The inclusion of a lubricant can improve the surface smoothness of the resulting molded article. The lubricant is not particularly limited, but it is preferable to contain at least one selected from the group consisting of behenamide, stearamide, erucamide, and oleamide. The inclusion of these lubricants can provide the resulting molded article with good lubricity (particularly external lubricity). Among these, it is preferable to contain behenamide and / or erucamide from the viewpoint of improving processability and productivity.

[0053] The lubricant may be behenamide, stearamide, erucamide, oleamide, or a combination of two or more of these. It may also be a combination of behenamide, stearamide, erucamide, or oleamide with a lubricant other than these (hereinafter referred to as "other lubricants"). Examples of other lubricants include, but are not limited to, alkylene fatty acid amides such as methylene bisstearic acid amide and ethylene bisstearic acid amide; polyethylene wax, oxidized polyester wax, glycerin monofatty acid esters such as glycerin monostearate, glycerin monobehenate, and glycerin monolaurate; organic acid monoglycerides such as succinic acid saturated fatty acid monoglycerides; sorbitan fatty acid esters such as sorbitan behenate, sorbitan stearate, and sorbitan laurate; polyglycerin fatty acid esters such as diglycerin stearate, diglycerin laurate, tetraglycerin stearate, tetraglycerin laurate, decaglycerin stearate, and decaglycerin laurate; and higher alcohol fatty acid esters such as stearyl stearate. The other lubricants may be used alone or in combination of two or more.

[0054] The content of the lubricant (when multiple lubricants are used, the total content) is not particularly limited as long as it can impart lubricity to the molded article, but is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, even more preferably 0.5 to 10 parts by weight, even more preferably 0.5 to 5 parts by weight, and particularly preferably 0.7 to 4 parts by weight, per 100 parts by weight of the total of P3HA (A) and poly(3-hydroxybutyrate) resin (C). When the content of the lubricant is within the above range, it is possible to obtain the effect as a lubricant while avoiding bleeding out of the lubricant onto the surface of the molded article.

[0055] <Other ingredients> The poly(3-hydroxyalkanoate)-based resin composition for molding may contain other components such as plasticizers, inorganic fillers, antioxidants, ultraviolet absorbers, colorants such as dyes and pigments, and antistatic agents, to the extent that the functionality of the resulting molded article is not impaired.

[0056] The plasticizer is not particularly limited, but examples thereof include modified glycerin-based compounds such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate; adipate-based compounds such as diethylhexyl adipate, dioctyl adipate, and diisononyl adipate; polyether ester-based compounds such as polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate; benzoate-based compounds; epoxidized soybean oil; epoxidized fatty acid 2-ethylhexyl; and sebacic acid monoesters. These may be used alone or in combination of two or more. Among the above plasticizers, modified glycerin-based compounds and polyether ester-based compounds are preferred due to their ease of availability and high effectiveness. These may be used alone or in combination of two or more.

[0057] The inorganic filler is not particularly limited, but examples thereof include clay, synthetic silicon, carbon black, barium sulfate, mica, glass fiber, whisker, carbon fiber, calcium carbonate, magnesium carbonate, glass powder, metal powder, kaolin, graphite, molybdenum disulfide, zinc oxide, etc. These may be used alone or in combination of two or more.

[0058] The antioxidant is not particularly limited, but examples thereof include phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, etc. These may be used alone or in combination of two or more.

[0059] The ultraviolet absorber is not particularly limited, but examples thereof include benzophenone compounds, benzotriazole compounds, triazine compounds, salicylic acid compounds, cyanoacrylate compounds, nickel complex compounds, etc. These may be used alone or in combination of two or more.

[0060] The colorants such as pigments and dyes are not particularly limited, and examples thereof include inorganic colorants such as titanium oxide, calcium carbonate, chromium oxide, cuprous oxide, calcium silicate, iron oxide, carbon black, graphite, titanium yellow, and cobalt blue, soluble azo pigments such as lake red, lithol red, and brilliant carmine, insoluble azo pigments such as dinitrile orange and fast yellow, phthalocyanine pigments such as monochlorophthalocyanine blue, polychlorophthalocyanine blue, and polybromophthalocyanine green, condensed polycyclic pigments such as indigo blue, perylene red, isoindolinone yellow, and quinacridone red, and dyes such as oracet yellow. These may be used alone or in combination of two or more.

[0061] The antistatic agent is not particularly limited, but examples thereof include low molecular weight antistatic agents such as fatty acid ester compounds, aliphatic ethanolamine compounds, and aliphatic ethanolamide compounds, and polymeric antistatic agents, etc. These may be used alone or in combination of two or more.

[0062] The content of each of the other components described above is not particularly limited as long as the effects of the invention are achieved, and can be appropriately determined by a person skilled in the art.

[0063] [Method for producing poly(3-hydroxyalkanoate)-based resin composition for molding] In the production method according to this embodiment, a poly(3-hydroxyalkanoate) resin composition for molding is produced by melting a poly(3-hydroxyalkanoate) resin composition containing at least P3HA (A) and poly(3-hydroxybutyrate) resin (C) under shear flow and then cooling and solidifying it. Specifically, the P3HA (A), poly(3-hydroxybutyrate) resin (C), and other optional components are melt-kneaded using an extruder, kneader, Banbury mixer, kneading rolls, or the like, followed by cooling and solidifying it. When melt-kneading, it is preferable to mix the components with care to avoid a decrease in molecular weight due to thermal decomposition.

[0064] In this embodiment, the following conditions are adopted when melting under shear flow. Shearing rate: 10~95sec -1 , Shear application time: 1 to 1,200 seconds, Shear application temperature: 100 to 185°C By adopting such conditions, the orientation of the molecular chains of the resin (C) is promoted, and crystallization after application of shear is promoted, allowing the resin composition for molding to be produced with high productivity. Furthermore, crystallization when the produced resin composition for molding is heated and melted for molding is also promoted, allowing molded articles to be produced with high productivity.

[0065] The upper limit of the shear rate is 90 sec -1 Less than 80 seconds is preferable. -1 On the other hand, the lower limit is 20 seconds. -1 More than 30 seconds is preferable. -1 More than 40 seconds is preferable. -1 More than 50 seconds is more preferable. -1 The above is particularly preferred.

[0066] The upper limit of the time for applying the shear force is preferably 1000 seconds or less, more preferably 800 seconds or less, while the lower limit is more preferably 10 seconds or more, even more preferably 50 seconds or more, even more preferably 100 seconds or more, particularly preferably 150 seconds or more, and most preferably 300 seconds or more.

[0067] The upper limit of the temperature when shear is applied may be 180°C or lower. The lower limit may be 110°C or higher, 120°C or higher, or 125°C or higher. The temperature when shear is applied refers to the resin temperature of the poly(3-hydroxyalkanoate) resin composition when shear is applied. The temperature when shear is applied may be a constant value or may vary within the above range.

[0068] In a preferred embodiment, the temperature at which shear is applied is preferably above the melting point of P3HA (A) but below the melting point of poly(3-hydroxybutyrate) resin (C). This embodiment further enhances the crystallization-promoting effect after shear application. Under these temperature conditions, crystallization of P3HA (A) is suppressed, while crystallization of resin (C) can proceed. Therefore, it is presumed that applying shear under these temperature conditions facilitates the formation of oriented crystals of resin (C), thereby improving the crystallization-promoting effect. The melting point of resin (C) is usually about 175°C, and the melting point of P3HA (A) varies depending on the composition ratio of the monomer units, but is generally 150°C or lower.

[0069] Specifically, the temperature at which shear is applied is preferably 155 to 175°C, more preferably 160 to 170°C. Within this temperature range, the crystallization-promoting effect after shear application can be further improved. In this embodiment, shear may be applied while maintaining the temperature constant within the range, or may be applied while decreasing the temperature within the range.

[0070] In the melt-molding step, it is preferable to melt all the crystals of the poly(3-hydroxyalkanoate) resin (C) contained in the resin composition. This can further enhance the crystallization-promoting effect due to the melt memory effect. It can also prevent foreign matter from being generated in the resin composition due to unmelted resin. In a preferred embodiment, it is preferable to melt all the crystals of the poly(3-hydroxyalkanoate) resin (C) once, and then reduce the temperature of the resin composition to a temperature below the melting point of the poly(3-hydroxybutyrate) resin (C) and apply shear.

[0071] When melt-kneading under shear flow, each component may be charged separately into an extruder, etc., or each component may be mixed in advance and then charged into an extruder, etc. When melt-kneading is performed using an extruder, the resulting poly(3-hydroxyalkanoate)-based resin composition for molding may be extruded into a strand shape and then cut to be processed into particle shapes (pellets) such as a bar shape, cylinder, elliptical cylinder, sphere, cube, or rectangular parallelepiped.

[0072] <Method of manufacturing molded body> The poly(3-hydroxyalkanoate)-based resin composition for molding obtained as described above can be heated and melted, followed by molding to produce a molded article having a desired shape. The molding method is not particularly limited as long as it includes a process of heating and melting the resin composition for molding, and then cooling and solidifying it into the desired shape. According to this embodiment, crystallization during molding of the resin composition for molding is promoted, allowing molded articles to be produced with good productivity. In particular, because the poly(3-hydroxyalkanoate)-based resin composition for molding has a melt memory effect, crystallization during molding can be promoted even if all the crystals of the poly(3-hydroxyalkanoate)-based resin contained in the resin composition are melted during the heating and melting process.

[0073] The conditions for heat-melting when producing a molded article are not particularly limited. Heat-melting may be performed while applying shear, or without applying shear. Even without applying shear, when the poly(3-hydroxyalkanoate)-based resin composition for molding obtained in this embodiment is used, crystallization is promoted, and molded articles can be produced with good productivity.

[0074] The shear rate when heating and melting while applying shear cannot be generally specified because it depends on the molding method, the size of the molding machine, the melting point and melt viscosity of the resin used, etc., but from the viewpoint of promoting crystallization by applying shear while avoiding thermal decomposition of P3HA (A) and poly(3-hydroxybutyrate) resin (C), a shear rate of 10 sec -1 It is preferable that the time is 30 seconds or more. -1More than 50 seconds is preferable. -1 The upper limit is not particularly limited, and is preferably 100,000 sec -1 may be less than 500 seconds -1 It may be the following:

[0075] The resin temperature during heating and melting when producing a molded article cannot be generally defined because it depends on the melting point and melt viscosity of the resin used. However, from the viewpoint of achieving good dispersibility while avoiding thermal decomposition of P3HA (A) and poly(3-hydroxybutyrate) resin (C), the temperature is preferably 130 to 200°C, more preferably 150 to 190°C, and even more preferably 160 to 185°C.

[0076] As described above, the poly(3-hydroxyalkanoate)-based resin composition for molding has a melt memory effect, and therefore, when heated and melted to produce a molded article, the crystallization-promoting effect can be achieved even if all the crystals of the poly(3-hydroxyalkanoate)-based resin contained in the resin composition are melted. Therefore, the resin temperature during heating and melting may be a temperature at which all the crystals of the poly(3-hydroxybutyrate) resin (C), which has a higher melting point, can melt, specifically 180°C or higher, preferably 185°C or higher. Furthermore, by melting all the crystals of the poly(3-hydroxybutyrate) resin (C) during production of the molded article, it is possible to avoid the generation of foreign matter in the molded article due to unmelted resin.

[0077] The poly(3-hydroxyalkanoate)-based resin composition for molding, or a molded article made from the composition, can be suitably used in agriculture, fisheries, forestry, horticulture, medicine, hygiene products, the food industry, clothing, non-clothing, packaging, automobiles, building materials, and other fields.

[0078] The following items list preferred aspects of the present disclosure, but the present invention is not limited to the following items. [Item 1] A method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding, comprising the step of melt-molding a poly(3-hydroxyalkanoate)-based resin composition containing a poly(3-hydroxyalkanoate)-based copolymer (A) and a poly(3-hydroxybutyrate) resin (C) under the following shear flow: Shearing rate: 10~95sec -1 , Shear application time: 1 to 1,200 seconds, Shear application temperature: 100 to 185°C [Item 2] Item 2. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to Item 1, wherein all crystals of the poly(3-hydroxybutyrate) resin (C) are melted during the melt molding. [Item 3] 3. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to item 1 or 2, wherein the weight-average molecular weight of the poly(3-hydroxyalkanoate)-based copolymer (A) (herein, the weight-average molecular weight refers to the weight-average molecular weight in terms of polystyrene as determined by gel permeation chromatography using chloroform as a solvent; the same applies hereinafter) is 100,000 or more and 1,000,000 or less. [Item 4] 4. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to any one of items 1 to 3, wherein the temperature when the shear is applied is 155 to 175°C. [Item 5] 5. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to any one of items 1 to 4, wherein the weight-average molecular weight of the poly(3-hydroxybutyrate) resin (C) is 160,000 or more and 1,000,000 or less. [Item 6] 6. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to any one of items 1 to 5, wherein the content of the poly(3-hydroxybutyrate) resin (C) is more than 5 parts by weight and not more than 50 parts by weight per 100 parts by weight of the poly(3-hydroxyalkanoate)-based copolymer (A). [Item 7] 7. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to any one of items 1 to 6, wherein the poly(3-hydroxyalkanoate)-based copolymer (A) is at least one selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate). [Item 8] 8. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to any one of items 1 to 7, wherein the poly(3-hydroxyalkanoate)-based copolymer (A) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). [Item 9] A method for producing a molded article containing a poly(3-hydroxyalkanoate) copolymer (A) and a poly(3-hydroxybutyrate) resin (C), comprising: A method for producing a molded article, comprising a step of heating and melting a resin composition for molding obtained by the method according to any one of items 1 to 8, and molding the composition. [Item 10] Item 10. The method for producing a molded article according to Item 9, wherein the resin temperature during the heat melting is 130°C or higher and 185°C or lower. [Item 11] Item 11. The method according to item 9 or 10, wherein all crystals of the poly(3-hydroxybutyrate) resin (C) are melted during the molding process. [Example]

[0079] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" are by weight. <Compounds used in Examples and Comparative Examples> <P3HA(A)> As P3HA(A), the following poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): P3HB3HH (Kaneka Corporation, Kaneka Biodegradable Polymer GreenPlanet (registered trademark)) was used. A-1: P3HB3HH in powder form with a (3-hydroxybutyrate) / (3-hydroxyhexanoate) ratio of 94.7 / 5.3 (mol% / mol%) and a weight average molecular weight Mw of 400,000 as measured by GPC. <P3HB(C)> The following was used as P3HB(C): C-1: 3-hydroxybutyrate = 100 (mol%), powdery PHB homopolymer with a weight average molecular weight Mw of 310,000 as measured by GPC. C-2: 3-hydroxybutyrate = 100 (mol%), powdery PHB homopolymer with a weight average molecular weight Mw of 830,000 as measured by GPC. C-3: 3-hydroxybutyrate = 100 (mol%), powdery PHB homopolymer with a weight average molecular weight Mw of 450,000 as measured by GPC.

[0080] The monomer composition ratio of P3HB3HH was determined as follows. Approximately 20 mg of P3HB3HH was added to 1 mL of a sulfuric acid-methanol mixture (15:85) and 1 mL of chloroform, sealed, and heated at 100°C for 140 minutes to obtain the methyl ester of the P3HB3HH decomposition product. After cooling, 0.5 mL of deionized water was added, mixed thoroughly, and allowed to stand until the aqueous and organic layers separated. The monomer unit composition of the P3HB3HH decomposition product in the separated organic layer was then analyzed by capillary gas chromatography. The ratio of 3-hydroxyhexanoate was calculated from the peak area obtained.

[0081] <Measurement of weight average molecular weight> The weight-average molecular weight of P3HB3HH and P3HB was measured by first dissolving the resin to be measured in chloroform and heating it in a hot water bath at 60°C for 0.5 hours, filtering the soluble matter through a disposable PTFE filter with a pore size of 0.45 μm, and then performing GPC measurement on the filtrate under the following conditions to determine the weight-average molecular weight. GPC measurement device: Shimadzu High Performance Liquid Chromatograph 20A System Column: Showa Denko KG 4A (1 column), K-806M (2 columns) Sample concentration: 1 mg / ml Free solution: Chloroform solution Free liquid flow rate: 1.0ml / min Sample injection volume: 100 μL Analysis time: 30 minutes Standard sample: Standard polystyrene

[0082] <Lubricant> As the lubricant, behenamide ("BNT22H" manufactured by Nippon Fine Chemicals Co., Ltd., hereinafter referred to as "BA") and erucamide ("Neutron S" manufactured by Nippon Fine Chemicals Co., Ltd., hereinafter referred to as "EA") were used.

[0083] The following evaluations were carried out for each of the Examples and Comparative Examples.

[0084] <Evaluation of torque during mixing> Each component of each Example or Comparative Example was melt-kneaded using a small kneader, Xplore series MC5, manufactured by DSM, at an extrusion temperature of 170°C and a screw rotation speed of 100 rpm, and the maximum torque during melt-kneading was evaluated.

[0085] <Evaluation of crystallization behavior when shear stress is applied in Examples and Comparative Examples in Table 1> Each component of Examples 1 to 4 or Comparative Example 1 was kneaded using a small kneader, Xplore series MC5, manufactured by DSM, at an extrusion temperature of 170°C and a screw rotation speed of 100 rpm, and then hot-pressed to a thickness of 200 μm using a compression molding machine (NSF-50) manufactured by Shinto Metal Industries, Ltd., at a temperature of 160°C and a pressure of 10 MPa to produce a film. First, in the first step (shear application step), the film was heated, sheared, and cooled under the following conditions using a polarizing microscope (Leica DM2700P) equipped with a heat shear stage (Linkam CSS450) equipped with quartz parallel plates. After further cooling to 120°C, the resin material was observed every minute for 10 minutes using a camera attached to the eyepiece while maintaining that temperature. The time when crystallization began, the crystal morphology, and the degree of crystal occupancy (whether total or partial) were evaluated. An example of a polarizing micrograph showing the morphology of the crystals observed with the polarizing microscope is shown in Figure 1. Heating temperature: 180°C (After reaching 180°C, hold at 180°C for 2 minutes) Heating rate: 30℃ / min Timing of shear application: During temperature drop from 180°C to 125°C. Shear application time: Adjusted by the rate of temperature decrease from 180°C to 125°C. When the rate of temperature decrease was 5°C / min, the time was 11 minutes, when the rate of temperature decrease was 7.5°C / min, the time was 8 minutes, and when the rate of temperature decrease was 10°C / min, the time was 6 minutes. Shearing rate: 50~100sec -1 (See Table 1)

[0086] Next, in the second step (a process for confirming the melt memory effect), the resin material, which was 120°C immediately after the first step, was heated to 185°C under the following conditions, held at that temperature, and then cooled without applying shear. After the temperature reached 110°C, the resin material was further cooled at the same rate while being observed every 10°C (every minute) using a camera attached to the eyepiece to evaluate the temperature at which crystallization began, the morphology of the crystals, and the degree to which the crystals occupied the field of view (whether total or partial) Heating temperature: 185°C (hold for 2 minutes after reaching 185°C) Heating rate: 30℃ / min Cooling rate: 10℃ / min.

[0087] Example 1 100 parts by weight of poly(3-hydroxyalkanoate) copolymer (A-1) was dry-blended with 5.3 parts by weight of poly(3-hydroxybutyrate) resin (C-1), 0.5 parts by weight of behenamide (BA), and 0.5 parts by weight of erucamide (EA). The mixture was then melt-kneaded and hot-pressed as described above at a shear rate of 50 sec. -1 The crystallization behavior was evaluated when shear was applied for 11 minutes at 100°C. The results are shown in Table 1.

[0088] Example 2 The crystallization behavior was evaluated in the same manner as in Example 1, except that the shear rate and shear application time were changed as shown in Table 1. The results are shown in Table 1.

[0089] Example 3 A poly(3-hydroxyalkanoate)-based resin composition for molding was prepared in the same manner as in Example 1, except that the amount of poly(3-hydroxybutyrate) resin (C-1) was changed as shown in Table 1. -1 The crystallization behavior was evaluated when shear was applied for 6 minutes at 100°C. The results are shown in Table 1.

[0090] Example 4 A poly(3-hydroxyalkanoate)-based resin composition for molding was prepared in the same manner as in Example 1, except that the poly(3-hydroxyalkanoate)-based copolymer (C-1) was replaced with the poly(3-hydroxyalkanoate)-based copolymer (C-2). The composition was then subjected to a shear rate of 50 sec. -1 The crystallization behavior was evaluated when shear was applied for 6 minutes at 100°C. The results are shown in Table 1.

[0091] (Comparative Example 1) 100 parts by weight of poly(3-hydroxyalkanoate) copolymer (A-1) was dry-blended with 5.3 parts by weight of poly(3-hydroxybutyrate) resin (C-1), 0.5 parts by weight of behenamide (BA), and 0.5 parts by weight of erucamide (EA), and then the mixture was melt-kneaded and hot-pressed as described above at a shear rate of 100 sec. -1 The crystallization behavior was evaluated when shear was applied for 6 minutes at 100°C. The results are shown in Table 1.

[0092] [Table 1]

[0093] As can be seen from Table 1, the poly(3-hydroxyalkanoate) resin compositions for molding in Examples 1 to 4 were subjected to a shear rate of 50 to 75 sec in the first step. -1 Crystallization after the application of shear was significantly accelerated, with a crystalline state known as "shishi" being observed throughout the sample. Crystallization also began quickly, occurring after 2 or 1 minute. In both examples, even though the poly(3-hydroxybutyrate) resin was heated to 185°C in the second step, at which point it completely melts, spherulites were observed throughout the sample, a result of the melt memory effect. The term "shishi" refers to a crystalline structure formed when the molecular chains of a resin are oriented and crystallization is induced, and refers to an extended chain crystal in which the molecular chains of the resin are crystallized in an extended state.

[0094] On the other hand, in Comparative Example 1, although a "shimmer" was observed after applying shear in the first step, crystallization began late, after 10 minutes, and the melt memory effect in the second step was limited to the appearance of partial spherulites.

[0095] From the above results, it is clear that the shear rate is 95 sec as in Comparative Example 1. -1 When the shear stress exceeds 100%, the crystallization promotion effect due to the application of shear stress in the first step is insufficient, and the melt memory effect in the second step is also low.

[0096] However, as shown in Examples 1 to 4, poly(3-hydroxyalkanoate) copolymer (A) was mixed with poly(3-hydroxybutyrate) resin (C) at a shear rate of 10 to 95 sec. -1It can be seen that when shear is applied for a time of 1 to 1,200 seconds and at a temperature of 100 to 185°C, the crystallization-promoting effect of the shear application is high, and furthermore, a poly(3-hydroxyalkanoate)-based resin composition for molding processing can be obtained that exhibits an excellent melt memory effect.

[0097] <Evaluation of crystallization behavior when shear stress is applied in Example 5 in Table 2> The components of Example 5 were mixed using a small mixer, Xplore series MC5, manufactured by DSM, at an extrusion temperature of 170°C and a screw rotation speed of 100 rpm, and then hot-pressed to a thickness of 200 μm using a compression molding machine (NSF-50) manufactured by Shinto Metal Industries, Ltd., at a temperature of 160°C and a pressure of 10 MPa to produce a film. Using a polarizing microscope (Leica DM2700P) equipped with a thermal shear stage (Linkam CSS450) equipped with quartz parallel plates, the film was first heated and cooled under the following conditions in the first step (shear application process), after which shear application was initiated. Shear application was continued at the same temperature for a set period, after which shear application was stopped and the film was cooled to 120°C. While maintaining the temperature at 120°C, the resin material was observed every minute for 10 minutes using a camera attached to the eyepiece. The time when crystallization began, the crystal morphology, and the degree of crystal occupancy (whether total or partial) were evaluated. Figure 1 shows an example of a polarizing micrograph showing the morphology of the crystals observed with the polarizing microscope. Heating temperature: 180°C (After reaching 180°C, hold at 180°C for 2 minutes) Heating rate: 30℃ / min Timing of shear application: The temperature is lowered from 180°C to 160°C, and when the temperature reaches 160°C, shear application is started. Shear application time: 6 minutes after reaching 160°C. Shearing rate: 50sec -1

[0098] Next, in the second step (a process for confirming the melt memory effect), the resin material, which was 120°C immediately after the first step, was heated to 180°C under the following conditions, held at that temperature, and then cooled without applying shear. After the temperature reached 120°C, the resin material was further cooled at the same rate while being observed every 5°C (every 0.5 minutes) using a camera attached to the eyepiece to evaluate the temperature at which crystallization began, the morphology of the crystals, and the degree to which the crystals occupied the field of view (whether total or partial) Heating temperature: 180°C (hold for 0.5 minutes after reaching 180°C) Heating rate: 30℃ / min Cooling rate: 10℃ / min.

[0099] Example 5 100 parts by weight of poly(3-hydroxyalkanoate) copolymer (A-1) was dry-blended with 5.3 parts by weight of poly(3-hydroxybutyrate) resin (C-1), 0.5 parts by weight of behenamide (BA), and 0.5 parts by weight of erucamide (EA). The mixture was then melt-kneaded and hot-pressed as described above at a shear rate of 50 sec. -1 The crystallization behavior was evaluated when shear was applied at 160°C for 6 minutes. The results are shown in Table 2.

[0100] Examples 6 and 7 The crystallization behavior was evaluated in the same manner as in Example 5, except that the amount of poly(3-hydroxybutyrate) resin (C-1) was changed as shown in Table 2. The results are shown in Table 2.

[0101] (Examples 8 to 10, 12) The crystallization behavior was evaluated in the same manner as in Example 5, except that the amount of poly(3-hydroxybutyrate) resin (C-1) was changed and further the shear rate, shear application time, or shear application temperature was changed as shown in Table 2. The results are shown in Table 2.

[0102] Example 11 The crystallization behavior was evaluated in the same manner as in Example 5, except that the poly(3-hydroxybutyrate) resin (C-1) was changed to the poly(3-hydroxybutyrate) resin (C-2). The results are shown in Table 2.

[0103] (Comparative Example 2) The crystallization behavior was evaluated in the same manner as in Example 5, except that the shear rate and shear application time were changed as shown in Table 2. The results are shown in Table 2.

[0104] [Table 2]

[0105] As can be seen from Table 2, the poly(3-hydroxyalkanoate)-based resin compositions for molding in Examples 5 to 12 were subjected to a shear rate of 50 to 95 sec in the first step. -1 Crystallization after the application of shear was significantly accelerated, with a crystalline state known as "shishi" being observed throughout the sample, and crystallization began quickly, occurring after 0 to 2 minutes. Furthermore, in all examples, despite the poly(3-hydroxybutyrate) resin being heated to 180°C in the second step, at which point it completely melts, spherulites were observed throughout the sample, due to the melt memory effect, and the temperature at which crystallization began was high, at 110°C to 120°C.

[0106] In particular, in Examples 5 to 11, in which the shear application temperature was in the range of 155 to 175°C, crystallization began sooner, after 0 to 1 minute, than in Example 12, in which the shear application temperature was 150°C, and excellent crystallization-promoting effects were obtained.

[0107] On the other hand, in Comparative Example 2, the shear rate was 100 sec -1 In the first step, crystallization was observed after shear was applied, but in the second step, only partial spherulites were observed, indicating that the melt memory effect was lower than in Examples 5 to 12.

Claims

1. A method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding, comprising the step of melt-molding a poly(3-hydroxyalkanoate)-based resin composition containing a poly(3-hydroxyalkanoate)-based copolymer (A) and a poly(3-hydroxybutyrate) resin (C) under the following shear flow: Shearing rate: 10-95sec －１ , time for applying shear: 1 to 1,200 seconds, temperature when applying shear: 100 to 185°C

2. 2. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to claim 1, wherein all crystals of the poly(3-hydroxybutyrate) resin (C) are melted during the melt molding.

3. 3. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to claim 1, wherein the temperature when the shear stress is applied is 155 to 175°C.

4. The weight average molecular weight of the poly(3-hydroxyalkanoate) copolymer (A) (here, the weight average molecular weight refers to the weight average molecular weight in terms of polystyrene, determined by gel permeation chromatography using chloroform as a solvent) 3. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to claim 1, wherein the molecular weight of the poly(3-hydroxyalkanoate)-based resin composition for molding is 100,000 or more and 1,000,000 or less.

5. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to claim 1 or 2, wherein the weight-average molecular weight of the poly(3-hydroxybutyrate) resin (C) is 160,000 or more and 1,000,000 or less.

6. 3. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to claim 1 or 2, wherein the content of the poly(3-hydroxybutyrate) resin (C) is more than 5 parts by weight and not more than 50 parts by weight per 100 parts by weight of the poly(3-hydroxyalkanoate)-based copolymer (A).

7. 3. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to claim 1 or 2, wherein the poly(3-hydroxyalkanoate)-based copolymer (A) is at least one selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate).

8. The method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding according to claim 1 or 2, wherein the poly(3-hydroxyalkanoate)-based copolymer (A) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

9. A method for producing a molded article containing a poly(3-hydroxyalkanoate) copolymer (A) and a poly(3-hydroxybutyrate) resin (C), comprising the steps of: A method for producing a molded article, comprising the step of heating and melting the resin composition for molding obtained by the method according to claim 1 or 2, and molding the composition.

10. The method for producing a molded article according to claim 9, wherein the resin temperature during the heating and melting is 130°C or higher and 185°C or lower.

11. The method according to claim 9, wherein all of the crystals of the poly(3-hydroxybutyrate) resin (C) are melted during the molding process.

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