Poly (3-hydroxyalkanoate)-based resin composition for molding and molded article thereof

Abstract

A poly (3-hydroxyalkanoate)-based resin composition for molding, which contains a poly (3-hydroxyalkanoate)-based copolymer (A) having a weight-average molecular weight of 100,000 to 1,000,000 (inclusive) and a poly (3-hydroxybutyrate) resin (C) having a weight-average molecular weight of 16,000 to 500,000 (inclusive). The content of the resin (C) is more than 5 parts by weight and 50 parts by weight or less relative to 100 parts by weight of the copolymer (A).

Description

Technical Field

[0001] The present invention relates to a poly(3-hydroxyalkanoate)-based resin composition for molding and a molded article thereof. Background Art

[0002] In recent years, plastic waste has become a burden on the global environment, with its impact on ecosystems, harmful gases produced during combustion, and global warming caused by the large amount of heat from combustion. As a material that can address these issues, the development of biodegradable plastics has been rapidly gaining momentum.

[0003] Among biodegradable plastics, those produced by microorganisms using plant-derived raw materials as a carbon source, particularly aliphatic polyester resins, are attracting attention from the perspectives of biodegradability and carbon neutrality. Among these, poly(3-hydroxyalkanoate) resins, such as poly(3-hydroxybutyrate) homopolymers, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymers, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymers, and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymers, are attracting significant attention.

[0004] Generally, the poly(3-hydroxyalkanoate)-based resins, particularly copolymerized poly(3-hydroxyalkanoate)-based resins, have a problem of low processability during melt molding due to their slow crystallization rate.

[0005] Regarding this problem, Patent Document 1 discloses a poly(3-hydroxyalkanoate)-based resin composition comprising a first and a second poly(3-hydroxyalkanoate)-based resin, wherein the melting point of the second polyhydroxyalkanoate is observed at a temperature lower than the melting point of the second polyhydroxyalkanoate measured alone.

[0006] Patent Document 2 discloses a polyester resin composition containing polyhydroxyalkanoate and low-melting-point polyhydroxybutyrate, wherein the low-melting-point polyhydroxybutyrate has a weight-average molecular weight of 5,000 to 50,000.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: International Publication No. 2015 / 146194

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2014-227543 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] The compositions described in Patent Documents 1 and 2 can promote the crystallization of poly(3-hydroxyalkanoate)-based resins, but this is not sufficient and further improvement is required.

[0013] Actual molding processes are often governed by shear flow. Under shear flow, the resin's molecular chains are oriented, which can be a major factor in promoting crystallization. Therefore, it is desirable to evaluate the crystallization rate under conditions that better reflect actual molding processes.

[0014] In view of the above-mentioned current situation, an object of the present invention is to provide a poly(3-hydroxyalkanoate)-based molding resin composition having an improved crystallization rate after application of shear, and a molded article thereof.

[0015] The present inventors have endeavored to evaluate the crystallization rate and crystal morphology using an apparatus capable of measuring crystallization after heating and shearing a molten resin, and to search for a resin composition that can achieve a significant crystallization-promoting effect under these conditions.

[0016] Solutions to the Problem

[0017] To solve the above-mentioned problems, the present inventors conducted intensive research and found that by adding a poly(3-hydroxybutyrate) resin having a weight-average molecular weight of 160,000 to 500,000 in a ratio of more than 5 parts by weight but less than 50 parts by weight to 100 parts by weight of a poly(3-hydroxyalkanoate)-based copolymer having a weight-average molecular weight of 100,000 to 1,000,000, crystallization after shearing can be promoted even when heated to 185°C or higher, at which the poly(3-hydroxybutyrate) resin is completely melted, thereby completing the present invention.

[0018] That is, the present invention relates to a poly(3-hydroxyalkanoate)-based resin composition for molding, comprising:

[0019] a poly(3-hydroxyalkanoate) copolymer (A) having a weight average molecular weight (herein, the weight average molecular weight refers to the weight average molecular weight in terms of polystyrene determined by gel permeation chromatography using a chloroform solvent. The same shall apply hereinafter) of 100,000 to 1,000,000; and

[0020] a poly(3-hydroxybutyrate) resin (C) having a weight average molecular weight of 160,000 to 500,000,

[0021] The content of the poly(3-hydroxybutyrate) resin (C) is more than 5 parts by weight and not more than 50 parts by weight relative to 100 parts by weight of the poly(3-hydroxyalkanoate) copolymer (A).

[0022] Furthermore, the present invention relates to a molded article comprising the poly(3-hydroxyalkanoate)-based molding resin composition.

[0023] In addition, the present invention also relates to a method for producing a molded body, the method comprising: -1 The step of melt-molding the poly(3-hydroxyalkanoate)-based molding resin composition under the above shear flow.

[0024] Effects of the Invention

[0025] According to the present invention, a poly(3-hydroxyalkanoate)-based resin composition for molding, in which the crystallization rate after shearing is improved, and a molded article thereof can be provided.

[0026] According to the present invention, the crystallization rate of the poly(3-hydroxyalkanoate) resin composition after shearing is increased, and therefore melt molding using the resin composition can be stably performed with good productivity under practical processing conditions.

[0027] Furthermore, since the torque during kneading can be controlled to a low value, heat generation due to kneading and thermal decomposition of the poly(3-hydroxyalkanoate)-based resin can be suppressed.

[0028] Furthermore, a molded article composed of the poly(3-hydroxyalkanoate)-based resin composition is less likely to generate foreign matter and can exhibit a good appearance.

[0029] According to a preferred embodiment of the present invention, during the molding process involving the steps of melting and cooling a molding material containing a poly(3-hydroxyalkanoate)-based resin, a wider range of applicable temperature conditions can be selected. Therefore, it is possible to produce molded articles that can be stably molded, have relatively uniform thickness and weight, and have a good appearance. Furthermore, productivity can be improved, enabling high-speed mass production of molded articles. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 These are diagrams explaining examples of polarizing microscope photographs showing the morphology of crystals observed in Examples or Comparative Examples and their evaluation methods. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0032] The resin composition of this embodiment is a resin composition mainly composed of a poly(3-hydroxyalkanoate) copolymer, which is used to form a molded article by heating and melting and then cooling and solidifying. In particular, by applying shear during heating and melting to promote crystallization, the productivity of the molded article can be improved.

[0033] The resin composition of the present embodiment is a poly(3-hydroxyalkanoate)-based resin composition comprising at least a poly(3-hydroxyalkanoate)-based copolymer (A) having a weight-average molecular weight of 100,000 to 1,000,000 and a poly(3-hydroxybutyrate) resin (C) having a weight-average molecular weight of 160,000 to 500,000.

[0034] <Poly(3-hydroxyalkanoate)-based copolymer (A)>

[0035] The poly(3-hydroxyalkanoate) copolymer (A) is a biodegradable aliphatic polyester (preferably a polyester without an aromatic ring) comprising at least one or two or more 3-hydroxyalkanoate units. In this application, the poly(3-hydroxyalkanoate) copolymer is also referred to as P3HA.

[0036] The 3-hydroxyalkanoate unit is preferably represented by the following general formula (1).

[0037] [-CHR-CH2-CO-O-] (1)

[0038] In the general formula (1), R represents C p H 2p+1 The alkyl group represented by is an integer of 1 to 15. Examples of R include linear or branched alkyl groups such as methyl, ethyl, propyl, methylpropyl, butyl, isobutyl, tert-butyl, pentyl, and hexyl. p is preferably 1 to 10, more preferably 1 to 8.

[0039] 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 3-hydroxyalkanoate units are contained as (R)-3-hydroxyalkanoate units.

[0040] 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 of all structural units (monomer units), more preferably 60 mol% or more, and even more preferably 70 mol% or more. The poly(3-hydroxyalkanoate) copolymer may contain only two or more 3-hydroxyalkanoate units as the structural units of the polymer, or may contain one or more units other than 3-hydroxyalkanoate units (e.g., 4-hydroxyalkanoate units) as the structural units of the polymer.

[0041] The poly(3-hydroxyalkanoate) copolymer (A) is preferably a copolymer containing 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) units and other hydroxyalkanoate units. The 3-hydroxybutyrate units are preferably all (R)-3-hydroxybutyrate units.

[0042] The other hydroxyalkanoate units may be 3-hydroxyalkanoate units other than 3HB units, or hydroxyalkanoate units other than 3-hydroxyalkanoate units (eg, 4-hydroxyalkanoate units). The other hydroxyalkanoate units may be comprised of one or more.

[0043] 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-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). In particular, from the viewpoints of productivity and mechanical properties of the resin composition, P3HB3HH or P3HB4HB is preferred, and P3HB3HH is particularly preferred.

[0044] P3HA can be produced by microorganisms. Such P3HA produced by microorganisms is generally composed solely of D- (R-) hydroxyalkanoic acid repeating units. Among P3HA produced by microorganisms, P3HB3HH, P3HB3HV, P3HB3HV3HH, and P3HB4HB are preferred from the perspective of ease of industrial production, with P3HB3HH, P3HB3HV, and P3HB4HB being more preferred, and P3HB3HH being particularly preferred. As P3HA, a single species may be used, or a combination of two or more species with different monomer types and ratios may be used.

[0045] P3HA-producing microorganisms are not particularly limited as long as they have the ability to produce P3HA. For example, the earliest P3HB-producing microorganism was Bacillus megaterium, discovered in 1925. Other known natural microorganisms include Cupriavidus necator (formerly classified as Alcaligenes eutrophus, Ralstonia eutropha) and Alcaligenes latus. These microorganisms accumulate P3HB in their cells.

[0046] In addition, as a producer of copolymers of 3HB and other hydroxyalkanoates, Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes eutrophus, which produces P3HB4HB, are known. In particular, with respect to P3HB3HH, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)), into which genes for the P3HA synthase group have been introduced, is preferably used to improve the productivity of P3HB3HH. Such microorganisms can be cultured under appropriate conditions to accumulate P3HA within the microbial cell. In addition to the above, genetically modified microorganisms into which various genes involved in P3HA synthesis have been introduced may be used depending on the P3HA to be produced, and the culture conditions including the type of substrate may be optimized.

[0047] The weight-average molecular weight of the poly(3-hydroxyalkanoate) copolymer (A) is within the range of 100,000 to 1,000,000. By setting the weight-average molecular weight of P3HA (A) to 100,000 or more, a molded article exhibiting excellent physical properties can be formed by cooling after melting. Furthermore, by combining it with the poly(3-hydroxybutyrate) resin (C) described below, crystallization can be promoted after the resin composition is melted and sheared, enabling the production of molded articles with good 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, making molding easier. The weight-average molecular weight of P3HA (A) is preferably 200,000 to 800,000. Alternatively, it may exceed 200,000. Furthermore, it is more preferably 250,000 to 700,000, and even more preferably 300,000 to 600,000.

[0048] The weight-average molecular weight of P3HA can be determined by gel permeation chromatography (GPC) (Shimadzu Corporation "High Performance Liquid Chromatography 20A System") using a polystyrene gel (Showa Denko KG 4A, K-806M) as a column and chloroform as the mobile phase, and the molecular weight can be determined as polystyrene-equivalent. A calibration curve is prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. Any column suitable for measuring the above-mentioned molecular weights can be used as the GPC column.

[0049] 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 setting the content within this range, the poly(3-hydroxyalkanoate) resin composition can have both flexibility and rigidity, and productivity can also be improved. The content is more preferably 1 to 20 mol%, further 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 3 mol% or more.

[0050] The content ratio of the above-mentioned 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, it refers to the molar ratio of each monomer unit contained in the entire mixture.

[0051] The monomer composition ratio in P3HA can be measured by gas chromatography or the like, and for example, reference can be made to the description of International Publication No. 2014 / 020838.

[0052] <Poly(3-hydroxybutyrate) resin (C)>

[0053] The poly(3-hydroxyalkanoate)-based molding resin composition of this embodiment further comprises a poly(3-hydroxybutyrate) resin (C). This resin (C) not only crystallizes more readily than poly(3-hydroxyalkanoate)-based copolymers, but also readily orients its molecular chains under melt shear, inducing crystallization. Therefore, even when heated to 185°C or higher, where the resin (C) is completely melted, shearing can promote crystallization of the resin composition. The use of this resin (C) promotes crystallization after shearing, enabling the production of molded articles with high productivity.

[0054] The poly(3-hydroxybutyrate) resin (C) refers to a homopolymer of 3-hydroxybutyrate, or a polymer containing a small amount of hydroxyalkanoate units other than 3-hydroxybutyrate units in addition to 3-hydroxybutyrate units. Specifically, the poly(3-hydroxybutyrate) resin (C) preferably contains 3-hydroxybutyrate units at a ratio exceeding 99 mol% and not more than 100 mol% of the total monomer content.

[0055] Hydroxyalkanoate units other than 3-hydroxybutyrate units that may be contained in the poly(3-hydroxybutyrate) resin (C) are not particularly limited as long as they are copolymerizable with the 3-hydroxybutyrate units. 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.

[0056] The weight average molecular weight of the poly(3-hydroxybutyrate) resin (C) is within the range of 160,000 to 500,000. By setting the weight average molecular weight of the resin (C) to 160,000 or more, the resin is easily oriented under melt shearing, thereby inducing crystallization. Therefore, by melting it and applying shearing, crystallization can be promoted, and a molded body can be manufactured with good productivity. On the other hand, by setting the weight average molecular weight of the resin (C) to 500,000 or less, foreign matter is less likely to be generated in the molded body, and further, processability is further improved, making molding easier. The weight average molecular weight of the resin (C) is preferably 180,000 to 480,000, more preferably 200,000 to 450,000, and particularly preferably 250,000 to 400,000.

[0057] From the viewpoint of suppressing the torque during kneading to a low value, the weight average molecular weight of the resin (C) is preferably smaller than the weight average molecular weight of P3HA (A), more preferably at least 100,000 smaller than the weight average molecular weight of P3HA (A), and even more preferably at least 150,000 smaller.

[0058] The amount of poly(3-hydroxybutyrate) resin (C) added is set within a range of more than 5 parts by weight and less than 50 parts by weight relative to 100 parts by weight of P3HA (A). Within this range, crystallization after shearing is promoted, and a molded body can be produced with good productivity. However, if the content of resin (C) is less than 5 parts by weight, it is difficult to exhibit the crystallization-promoting effect caused by the use of poly(3-hydroxybutyrate) resin (C), and since the torque during kneading becomes large, excessive heat generation is generated, which easily causes thermal decomposition of the poly(3-hydroxyalkanoate) resin. In addition, if it exceeds 50 parts by weight, foreign matter is easily generated in the molded body. The lower limit of the amount of resin (C) is preferably more than 7 parts by weight, more preferably more than 8 parts by weight, and even more preferably more than 10 parts by weight. In addition, it may also exceed 10 parts by weight, and may also be more than 15 parts by weight. The upper limit is preferably less than 40 parts by weight, more preferably less than 30 parts by weight, and particularly preferably less than 20 parts by weight.

[0059] Unlike the foamed resin particles disclosed in International Publication No. 2019 / 146555 or International Publication No. 2022 / 054870, the poly(3-hydroxyalkanoate)-based molding resin composition of this embodiment is an unfoamed resin composition, preferably a resin composition that substantially does not contain bubbles inside.

[0060] Since the poly(3-hydroxyalkanoate)-based molding resin composition of the present embodiment is not foamed, its density is relatively high, and preferably exceeds 0.3 g / cm 3 , more preferably 0.5 g / cm 3 More preferably, 0.7 g / cm 3 The upper limit is not particularly limited, and can be, for example, 1.6 g / cm 3 Below, 1.4g / cm2 is also possible 3 The density of the resin composition can be determined by the method described in JIS K0061 (Determination of density and specific gravity of chemicals) or JIS Z8807 (Determination of density and specific gravity of solids).

[0061] The poly(3-hydroxyalkanoate)-based molding resin composition of this embodiment may optionally contain at least one selected from other resins, crystal nucleating agents, and lubricants in addition to P3HA (A) and poly(3-hydroxybutyrate) resin (C).

[0062] <Other resins>

[0063] The poly(3-hydroxyalkanoate)-based molding resin composition may contain any other resin that does not correspond to P3HA (A) and poly(3-hydroxybutyrate) resin (C). While the other resin is not particularly limited, it is preferably a resin that does not significantly reduce compatibility, molding processability, or the mechanical properties of the resulting molded article when the poly(3-hydroxyalkanoate)-based molding resin composition is molded. Furthermore, when the resulting molded article is used for applications requiring biodegradability, the other resin is preferably a biodegradable resin.

[0064] Examples of the other resins include aliphatic polyesters formed by the polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid, and aliphatic aromatic polyesters containing both an aliphatic compound and an aromatic compound 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). These other resins may be used alone or in combination of two or more.

[0065] When the poly(3-hydroxyalkanoate)-based molding resin composition contains the aforementioned 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, relative to 100 parts by weight combined of the P3HA (A) and the poly(3-hydroxybutyrate) resin (C). Alternatively, the content may be 10 parts by weight or less, 5 parts by weight or less, or even 1 part by weight or less. The lower limit of the content of the other resin is not particularly limited and may be 0 parts by weight.

[0066] <Crystallization nucleating agent>

[0067] The poly(3-hydroxyalkanoate)-based molding resin composition may further contain a crystallization nucleating agent. The inclusion of a crystallization nucleating agent in the poly(3-hydroxyalkanoate)-based molding resin composition further promotes crystallization of the resin component, thereby improving molding speed, productivity, and the like.

[0068] The crystal nucleating agent is not particularly limited, and conventionally known crystal nucleating agents can be used, and examples thereof 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, and dicarboxylic acid diols. Dicarboxylic acid derivatives such as methyl ester, dibutyl adipate, diisodecyl adipate, and dibutyl sebacate; cyclic compounds containing a C=O functional group and a functional group selected from NH, S, and O within the molecule, such as indigo, quinacridone, and quinacridone carmine; sorbitol derivatives such as dibenzylidene sorbitol and bis(p-methylbenzylidene)sorbitol; compounds containing a nitrogen-containing heterocyclic aromatic nucleus such as pyridine, triazine, and imidazole; phosphate compounds, bisamides of higher fatty acids, and metal salts of higher fatty acids. These crystal nucleating agents can be used alone or in combination of two or more.

[0069] The content of the crystallization nucleating agent is not particularly limited as long as it can promote crystallization of the resin component, 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, relative to 100 parts by weight of the total of P3HA (A) and poly(3-hydroxybutyrate) resin (C). When the content of the crystallization nucleating agent is within this range, a decrease in viscosity during molding and in the physical properties of the molded article can be suppressed while achieving the effect of the crystallization nucleating agent.

[0070] However, the above-mentioned poly (3-hydroxyalkanoate) resin composition for molding processing can also be substantially free of sugar alcohols such as pentaerythritol. Substantially free of sugar alcohols means that the amount of sugar alcohols added is less than 0.05 parts by weight relative to a total of 100 parts by weight of P3HA (A) and poly (3-hydroxybutyrate) resin (C). It can also be less than 0.01 parts by weight. For the method of substantially free of sugar alcohols, the problem of sugar alcohols seeping out of the resin composition and the contamination of the manufacturing equipment caused by it can be avoided. According to this embodiment, even if sugar alcohols as crystallization nucleating agents are substantially not added, good productivity can be achieved.

[0071] <Lubricant>

[0072] The poly(3-hydroxyalkanoate) resin composition for molding can further contain a lubricant. By containing a lubricant, the surface smoothness of the resulting molded body can be improved. The lubricant is not particularly limited, but preferably contains at least one selected from behenamide, stearamide, erucamide, and oleamide. By containing these lubricants, the resulting molded body can have good lubricity (particularly, external lubricity). Among them, from the viewpoint of improving processability and productivity, it is preferred to contain behenamide and / or erucamide.

[0073] As the lubricant, behenamide, stearamide, erucamide, oleamide, or a combination of two or more thereof may be used. A combination of behenamide, stearamide, erucamide, or oleamide with a lubricant other than these (hereinafter referred to as "the other lubricant") may also be used. Examples of such other lubricants include, but are not limited to, alkylene fatty acid amides such as methylenebisstearamide and ethylenebisstearamide; monoglycerides such as polyethylene wax, oxidized polyester wax, glyceryl monostearate, glyceryl monobehenate, and glyceryl monolaurate; organic acid monoglycerides such as succinic acid saturated fatty acid monoglyceride; sorbitan fatty acid esters such as sorbitan behenate, sorbitan stearate, and sorbitan laurate; polyglycerol fatty acid esters such as diglyceryl stearate, diglyceryl laurate, tetraglyceryl stearate, tetraglyceryl laurate, decaglyceryl stearate, and decaglyceryl laurate; and higher alcohol fatty acid esters such as stearyl stearate. These other lubricants may be used alone or in combination of two or more.

[0074] The content of the lubricant (the total content when multiple lubricants are used) is not particularly limited as long as it can impart lubricity to the molded article. However, it 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, relative to 100 parts by weight of the total of P3HA (A) and poly(3-hydroxybutyrate) resin (C). When the lubricant content is within this range, the lubricant can be prevented from seeping onto the surface of the molded article while achieving its lubricant effect.

[0075] <The other ingredients>

[0076] The poly(3-hydroxyalkanoate)-based molding resin composition may contain other components such as a plasticizer, an inorganic filler, an antioxidant, an ultraviolet absorber, a colorant such as a dye or pigment, and an antistatic agent, as long as the functions of the obtained molded article are not impaired.

[0077] The plasticizers are not particularly limited, but include, for example, modified glycerin compounds such as diacetylated monolaurate, diacetylated monocaprylate, and diacetylated monocaprate; adipate compounds such as diethylhexyl adipate, dioctyl adipate, and diisononyl adipate; polyetherester compounds such as polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate; benzoate compounds; epoxidized soybean oil; epoxidized 2-ethylhexyl fatty acid; and sebacic acid monoesters. These can be used alone or in combination of two or more. Among the above plasticizers, modified glycerin compounds and polyetherester compounds are preferred due to their ease of availability and high effectiveness. These can be used alone or in combination of two or more.

[0078] The inorganic filler is not particularly limited, and examples thereof include clay, synthetic silica, 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.

[0079] The antioxidant is not particularly limited, and 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.

[0080] The ultraviolet absorber is not particularly limited, and examples thereof include benzophenone compounds, benzotriazole compounds, triazine compounds, salicylic acid compounds, cyanoacrylate compounds, nickel complex salt compounds, etc. These may be used alone or in combination of two or more.

[0081] The coloring agents such as the pigments and dyes are not particularly limited, and examples thereof include inorganic coloring agents such as titanium oxide, calcium carbonate, chromium oxide, cuprous oxide, calcium silicate, iron oxide, carbon black, graphite, titanium yellow, and cobalt blue; lake red ( ), soluble azo pigments such as Lithol Scarlet and Brilliant Carmine; insoluble azo pigments such as Dinitroaniline Orange and Fast Yellow; phthalocyanine pigments such as Monochlorophthalocyanine Blue, Polychlorophthalocyanine Blue, and Polybrominated Phthalocyanine Green; condensed polycyclic pigments such as Indigo, Perylene Red, Isoindolinone Yellow, and Quinacridone Red; dyes such as Oracet Yellow, etc. These may be used alone or in combination of two or more.

[0082] The antistatic agent is not particularly limited, and examples thereof include low-molecular antistatic agents such as fatty acid ester compounds, aliphatic ethanolamine compounds, and aliphatic ethanolamide compounds, and high-molecular antistatic agents, etc. These may be used alone or in combination of two or more.

[0083] The content of each of the other components described above is not particularly limited as long as the effects of the invention can be achieved, and can be appropriately set by those skilled in the art.

[0084] [Method for producing a poly(3-hydroxyalkanoate)-based resin composition for molding]

[0085] The poly(3-hydroxyalkanoate) resin composition for molding of the present embodiment can be manufactured by a known method. Specifically, a method of melt-kneading P3HA (A), poly(3-hydroxybutyrate) resin (C), and any other components using an extruder, a kneader, a Banbury mixer, a mixing roll, etc. can be cited. During melt-kneading, it is preferred to mix with attention to the decrease in molecular weight due to thermal decomposition. Alternatively, the poly(3-hydroxyalkanoate) resin composition for molding can be manufactured by dissolving each component in a soluble solvent and then removing the solvent.

[0086] When producing by melt kneading, the components may be fed separately into an extruder, etc., or they may be mixed in advance and then fed into an extruder, etc. When melt kneading is performed in an extruder, the obtained poly(3-hydroxyalkanoate)-based resin composition for molding can be extruded into a strip and then cut into particles in the form of rods, cylinders, elliptical cylinders, spheres, cubes, or rectangular parallelepipeds.

[0087] The resin temperature during melt kneading cannot be uniformly specified because it depends on the melting point, melt viscosity, etc. of the resin used. However, from the viewpoint of avoiding thermal decomposition of P3HA (A) and poly (3-hydroxybutyrate) resin (C) while achieving good dispersibility, it is preferably 140 to 200°C, more preferably 150 to 195°C, and even more preferably 160 to 190°C.

[0088] <Method for producing a molded article>

[0089] A molded body can be manufactured from a poly(3-hydroxyalkanoate)-based molding resin composition. The molding method is not particularly limited as long as it includes a molding method that heats the resin composition and melts it, and cools and solidifies it. According to this embodiment, since the poly(3-hydroxyalkanoate)-based resin composition is melted and the crystallization rate after shearing is increased, it is preferred that the heating and melting during molding be performed under shear flow conditions. At this point, melt molding using the resin composition can be stably implemented with good productivity under practical processing conditions.

[0090] The shear rate during molding depends on the molding method, the size of the molding machine, the melting point and melt viscosity of the resin used, and therefore cannot be uniformly specified. However, from the viewpoint of avoiding thermal decomposition of P3HA (A) and poly (3-hydroxybutyrate) resin (C) and promoting crystallization by applying shear, 10 seconds is preferred. -1 More than 30 seconds, more preferably 30 seconds -1 More than 50 seconds, more preferably -1 The upper limit is not particularly limited and can be 100,000 seconds. -1 Below, 500 seconds is also possible -1 the following.

[0091] The resin temperature during molding cannot be uniformly specified because it depends on the melting point and melt viscosity of the resin used. However, from the viewpoint of avoiding thermal decomposition of P3HA (A) and poly (3-hydroxybutyrate) resin (C) and achieving good dispersibility, it is preferably 140 to 200°C, more preferably 150 to 195°C, and even more preferably 160 to 190°C.

[0092] The poly(3-hydroxyalkanoate)-based molding resin composition or a molded article thereof can be suitably used in agriculture, fisheries, forestry, horticulture, medicine, sanitary products, food industry, clothing, non-clothing materials, packaging, automobiles, building materials, and other fields.

[0093] Preferred aspects of the present application are listed in the following items, but the present invention is not limited to the following items.

[0094] [Project 1]

[0095] A poly(3-hydroxyalkanoate)-based resin composition for molding processing, comprising:

[0096] a poly(3-hydroxyalkanoate) copolymer (A) having a weight average molecular weight (herein, the weight average molecular weight refers to the weight average molecular weight in terms of polystyrene determined by gel permeation chromatography using a chloroform solvent. The same shall apply hereinafter) of 100,000 to 1,000,000; and

[0097] a poly(3-hydroxybutyrate) resin (C) having a weight average molecular weight of 160,000 to 500,000,

[0098] The content of the poly(3-hydroxybutyrate) resin (C) is more than 5 parts by weight and not more than 50 parts by weight relative to 100 parts by weight of the poly(3-hydroxyalkanoate) copolymer (A).

[0099] [Project 2]

[0100] The poly(3-hydroxyalkanoate)-based molding resin composition according to item 1, wherein

[0101] The poly (3-hydroxyalkanoate) copolymer (A) is at least one selected from 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).

[0102] [Item 3]

[0103] The poly(3-hydroxyalkanoate)-based molding resin composition according to item 1 or 2, wherein

[0104] The poly(3-hydroxyalkanoate) copolymer (A) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0105] [Item 4]

[0106] A molded article comprising the poly(3-hydroxyalkanoate)-based molding resin composition according to any one of items 1 to 3.

[0107] [Item 5]

[0108] The molded article according to item 4, wherein

[0109] The molded body is sheared at a speed of 10 sec -1 Melt molding under shear flow above 30°C.

[0110] [Item 6]

[0111] The poly(3-hydroxyalkanoate)-based molding resin composition described in any one of items 1 to 3 is subjected to a shearing speed of 10 sec -1 The above process of melt molding under shear flow.

[0112] Example

[0113] The present invention will be described in more detail below with reference to the following examples, but the present invention is not limited to these examples. It should be noted that "parts" and "%" in the examples are by weight.

[0114] <Compounds used in Examples and Comparative Examples>

[0115] <P3HA(A)>

[0116] As P3HA (A), the following poly (3-hydroxybutyrate-co-3-hydroxyhexanoate): P3HB3HH (manufactured by Kaneka Corporation, Kaneka Biodegradable Polymer GreenPlanet (registered trademark)) was used.

[0117] A-1: (3-hydroxybutyrate) / (3-hydroxyhexanoate)=94.7 / 5.3 (mol% / mol%), powdery P3HB3HH having a weight average molecular weight Mw of 400,000 as measured by GPC.

[0118] A-2: (3-hydroxybutyrate) / (3-hydroxyhexanoate)=94.5 / 5.5 (mol% / mol%), powdery P3HB3HH having a weight average molecular weight Mw of 240,000 as measured by GPC.

[0119] <P3HB(C)>

[0120] The following P3HB was used as P3HB.

[0121] C-1: 3-Hydroxybutyrate = 100 (mol %), a powdery PHB homopolymer having a weight average molecular weight Mw of 310,000 as measured by GPC.

[0122] C-2: 3-Hydroxybutyrate = 100 (mol %), a powdery PHB homopolymer having a weight average molecular weight Mw of 200,000 as measured by GPC.

[0123] C-3: 3-Hydroxybutyrate = 100 (mol %), a powdery PHB homopolymer having a weight average molecular weight Mw of 95,000 as measured by GPC.

[0124] C-4: 3-Hydroxybutyrate = 100 (mol %), a powdery PHB homopolymer having a weight average molecular weight Mw of 600,000 as measured by GPC.

[0125] The monomer composition ratio of P3HB3HH was determined as follows. To approximately 20 mg of P3HB3HH, 1 mL of a sulfuric acid-methanol mixture (15:85) and 1 mL of chloroform were added, the mixture was 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 removed organic layer was then analyzed by capillary gas chromatography. The ratio of 3-hydroxyhexanoate was calculated from the peak area obtained.

[0126] <Measurement of Weight Average Molecular Weight>

[0127] The weight-average molecular weight of P3HB3HH and P3HB was determined as follows: First, the resin to be measured was dissolved in chloroform and heated in a 60°C warm water bath for 0.5 hours. The soluble component was filtered through a 0.45 μm pore size treated filter made of PTFE. The filtrate was then used to perform GPC measurement under the following conditions to determine the weight-average molecular weight.

[0128] GPC measurement equipment: Shimadzu Corporation High Performance Liquid Chromatography 20A system

[0129] Chromatographic columns: Showa Denko KG 4A (1 column), K-806M (2 columns)

[0130] Sample concentration: 1mg / ml

[0131] Eluent: chloroform solution

[0132] Eluent flow rate: 1.0 ml / min

[0133] Sample injection volume: 100 μL

[0134] Analysis time: 30 minutes

[0135] Standard sample: standard polystyrene

[0136] <Lubricant>

[0137] As lubricants, behenamide ("BNT22H" manufactured by Nippon Seika Co., Ltd., hereinafter referred to as "BA") and erucamide ("NEUTRON S" manufactured by Nippon Seika Co., Ltd., hereinafter referred to as "EA") were used.

[0138] In each of the Examples and Comparative Examples, the following evaluations were performed.

[0139] <Evaluation of Torque during Kneading>

[0140] The resin compositions obtained in Examples 1 to 6 or Comparative Examples 1 to 6 were melt-kneaded using a compact kneader Xplore series MC5 manufactured by DSM at an extrusion temperature of 170° C. and a screw speed of 100 rpm, and the maximum torque during melt-kneading was evaluated.

[0141] <Evaluation of Crystallization Behavior Under Shear>

[0142] After mixing the resin compositions obtained in Examples 1 to 6 or Comparative Examples 1 to 6 using a small mixer Xplore series MC5 manufactured by DSM at an extrusion temperature of 170°C and a screw speed of 100 rpm, the films were 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 films. Using a polarizing microscope (DM2700P manufactured by Leica) equipped with a heated shearing stage (CSS450 manufactured by Linkam) with a parallel plate made of quartz, the films were heated, sheared, and cooled under the following conditions. The resin material that was cooled to 125°C was observed every minute for 10 minutes using a camera installed in the eyepiece while maintaining its temperature, and the crystallization start time, crystal morphology, and the proportion of crystals in the field of view (all or part) were evaluated. An example of a polarizing microscope photograph showing the crystal morphology observed in a polarizing microscope is shown in FIG. Figure 1 .

[0143] Heating temperature: 185°C (after reaching 185°C, maintain at 185°C for 2 minutes)

[0144] Heating speed: 30℃ / min

[0145] Shearing time: 90 seconds after reaching 185°C and for 30 seconds, and during cooling from 185°C to 125°C

[0146] Shear speed: 100 sec -1

[0147] Cooling: from 185℃ to 125℃

[0148] Cooling rate: 10℃ / min

[0149] <Evaluation of Foreign Matter in Film>

[0150] To evaluate crystallization behavior, 50 mm x 50 mm samples were cut from the resulting 200 μm-thick film. Foreign particles with a major axis size of 10 μm or greater in these samples were counted using a Peak Scale Lupe (magnification: 20) manufactured by Tokai Sangyo Co., Ltd. The number of foreign particles was compared with that of the sample of Comparative Example 1, prepared without the addition of P3HB(C), and evaluated according to the following criteria.

[0151] ○: No increase in the number of foreign matter was observed compared to Comparative Example 1.

[0152] ×: Compared with Comparative Example 1, the number of foreign matter increased.

[0153] (Example 1)

[0154] 100 parts by weight of the poly(3-hydroxyalkanoate) copolymer (A-1), 10 parts by weight of the poly(3-hydroxybutyrate) resin (C-2), 0.5 parts by weight of behenamide (BA), and 0.5 parts by weight of erucamide (EA) were dry-blended, melt-kneaded, and hot-pressed by the above-described method, with a shear rate of 100 seconds. -1 The results are shown in Table 1.

[0155] (Examples 2 and 3)

[0156] A poly(3-hydroxyalkanoate)-based molding resin composition was prepared in the same manner as in Example 1 except that the amount of the poly(3-hydroxybutyrate) resin (C) was changed as shown in Table 1. The composition was subjected to a shearing rate of 100 sec. -1 The results are shown in Table 1.

[0157] (Example 4)

[0158] A poly(3-hydroxyalkanoate)-based molding resin composition was prepared in the same manner as in Example 1 except that the poly(3-hydroxyalkanoate)-based copolymer (C-2) was replaced with the poly(3-hydroxyalkanoate)-based copolymer (C-1). The shear rate was applied for 100 seconds. -1 The results are shown in Table 1.

[0159] (Examples 5 and 6)

[0160] A poly(3-hydroxyalkanoate)-based molding resin composition was prepared in the same manner as in Example 4 except that the amount of the poly(3-hydroxybutyrate) resin (C) was changed as shown in Table 1. The composition was subjected to a shearing rate of 100 sec. -1 The results are shown in Table 1.

[0161] (Comparative Examples 1 and 2)

[0162] 0.5 parts by weight of behenamide (BA) and 0.5 parts by weight of erucamide (EA) were dry-blended with 100 parts by weight of the poly(3-hydroxyalkanoate) copolymer (A-1) or (A-2), and then melt-kneaded and hot-pressed by the above-mentioned method, with a shear rate of 100 seconds. -1 The results are shown in Table 1.

[0163] (Comparative Example 3)

[0164] 5 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) were dry-blended with 100 parts by weight of poly(3-hydroxyalkanoate) copolymer (A-1), and then melt-kneaded and hot-pressed by the above-mentioned method, with a shear rate of 100 seconds. -1 The results are shown in Table 1.

[0165] (Comparative Examples 4 to 6)

[0166] A poly(3-hydroxyalkanoate)-based molding resin composition was prepared in the same manner as in Comparative Example 3 except that the type of poly(3-hydroxybutyrate) resin (C) was changed. The composition was subjected to a shearing rate of 100 sec. -1 The results are shown in Table 1.

[0167]

[0168] The following results can be seen from Table 1: The poly(3-hydroxyalkanoate)-based molding resin compositions of Examples 1 to 6 did not have excessively high torque during melt kneading. When heated to 185°C where the poly(3-hydroxybutyrate) resin was completely melted, and a shear rate of 100 seconds was applied, the torque was not too high. -1 Crystallization after shearing was also significantly promoted, with a crystalline state called "shish" observed throughout, and the start of crystallization was advanced to 3 minutes or 1 minute later. In addition, the number of foreign matter observed in the film did not increase compared to Comparative Example 1.

[0169] It should be noted that the term "shish-kebab crystals" refers to a crystalline structure formed when the molecular chains of the resin are oriented and crystallization is induced, that is, extended chain crystals in which crystallization occurs while the molecular chains of the resin are extended.

[0170] On the other hand, in Comparative Example 1, the onset of crystallization was delayed to 10 minutes after shearing, and no "shake-shake" crystals were observed, with only spherulites visible in some areas. Furthermore, in Comparative Examples 2 and 5, no crystallization after shearing was observed. Furthermore, in Comparative Examples 3, 4, and 6, a crystalline state known as "shake-shake" crystals was observed, but only in some areas. Furthermore, in Comparative Example 6, the amount of foreign matter in the film tended to increase compared to Comparative Example 1.

[0171] The above results show that, as shown in Comparative Examples 1 and 2, when no poly(3-hydroxybutyrate) resin (C) is used, crystallization after shearing is not sufficiently promoted. Furthermore, as shown in Comparative Examples 3 to 6, when the poly(3-hydroxybutyrate) resin (C) is added in an amount of 5 parts by weight, the effect of promoting crystallization after shearing is insufficient. In particular, as shown in Comparative Example 5, when a poly(3-hydroxybutyrate) resin with a weight-average molecular weight of less than 160,000 is used, crystallization after shearing is not promoted. Furthermore, as shown in Comparative Example 6, when a poly(3-hydroxybutyrate) resin with a weight-average molecular weight of more than 500,000 is used, the number of foreign matter observed in the film increases.

[0172] However, as shown in Examples 1 to 6, it can be seen that by adding a poly(3-hydroxybutyrate) resin (C) having a weight-average molecular weight of 160,000 to 500,000 in an amount exceeding 5 parts by weight to 100 parts by weight of the poly(3-hydroxyalkanoate) copolymer (A), a poly(3-hydroxyalkanoate) resin composition can be obtained in which crystallization after application of shear is greatly promoted and foreign matter is less likely to be generated in the molded article.

Claims

1. A poly(3-hydroxyalkanoate)-based resin composition for molding, comprising: a poly(3-hydroxyalkanoate) copolymer (A) having a weight average molecular weight of 100,000 to 1,000,000, and a poly(3-hydroxybutyrate) resin (C) having a weight average molecular weight of 160,000 to 500,000, in, The content of the poly(3-hydroxybutyrate) resin (C) is more than 5 parts by weight and less than 50 parts by weight relative to 100 parts by weight of the poly(3-hydroxyalkanoate) copolymer (A). The weight average molecular weight refers to a weight average molecular weight in terms of polystyrene determined by gel permeation chromatography using a chloroform solvent, and the same shall apply hereinafter.

2. The poly(3-hydroxyalkanoate)-based molding resin composition according to claim 1, wherein The poly (3-hydroxyalkanoate) copolymer (A) is at least one selected from 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).

3. The poly(3-hydroxyalkanoate)-based molding resin composition according to claim 1 or 2, wherein The poly(3-hydroxyalkanoate) copolymer (A) is poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). A molded article comprising the poly(3-hydroxyalkanoate)-based molding resin composition according to claim 1 or 2.

5. The molded article according to claim 4, wherein The molded body is sheared at a speed of 10 sec -1 Melt molding under shear flow above 30°C.

6. A method for producing a molded body, comprising: The poly(3-hydroxyalkanoate)-based molding resin composition according to claim 1 or 2 is subjected to a shearing speed of 10 sec -1 The above process of melt molding under shear flow.

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