Blow-molded body

Abstract

According to the present invention, a poly(3-hydroxyalkanoate) resin component contains: a copolymer (A) of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, wherein the content ratio of the other hydroxyalkanoate unit is from 1% by mole to 6% by mole; and a copolymer (B) of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, wherein the content ratio of the other hydroxyalkanoate unit is 24% by mole or more. In the poly(3-hydroxyalkanoate) resin component, the ratio of the copolymer (A) is from 40% by weight to 90% by weight, while the ratio of the copolymer (B) is from 10% by weight to 60% by weight. The 50% fracture energy of the molded body as determined by a Dupont impact test is 0.3 J or more.

Description

[Technical Field]

[0001] The present invention relates to a blow-molded or injection-molded article containing a poly(3-hydroxyalkanoate)-based resin component. [Background technology]

[0002] In recent years, the separate collection and composting of food waste has been promoted, particularly in Europe, and there is a demand for plastic products that can be composted together with food waste. Furthermore, with marine pollution caused by microplastics coming to the forefront, there is hope for the development of plastics that can be decomposed in seawater.

[0003] Poly(3-hydroxyalkanoate) resins are thermoplastic polyesters that are produced and accumulated as energy storage substances within the cells of many microbial species. They are also biodegradable not only in soil but also in seawater, and are therefore attracting attention as a material that can solve the above problems.

[0004] Patent Document 1 describes a bottle container made of poly(3-hydroxybutyrate) resin and having a side wall thickness of 0.1 to 5.0 mm. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2020 / 095799 Summary of the Invention [Problem to be solved by the invention]

[0006] When attempting to produce blow-molded or injection-molded articles using poly(3-hydroxyalkanoate) resins reported to date, molding has been difficult, and even if molding is possible, the impact resistance of the molded articles is insufficient, and improvements in these respects are required.

[0007] In view of the above-mentioned current situation, the present invention aims to provide a blow-molded or injection-molded article that contains a poly(3-hydroxyalkanoate)-based resin component and has good moldability and excellent impact resistance. [Means for solving the problem]

[0008] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they discovered that blow-molded or injection-molded articles containing a poly(3-hydroxyalkanoate)-based resin component, which use two types of poly(3-hydroxyalkanoate)-based resins with different constituent monomer content ratios in a specific ratio, have good moldability and excellent impact resistance, and have thus completed the present invention.

[0009] That is, the present invention provides a blow- or injection-molded article containing a poly(3-hydroxyalkanoate)-based resin component, the poly(3-hydroxyalkanoate) resin component comprises a copolymer (A) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 1 to 6 mol %, and a copolymer (B) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 24 mol % or more; In the poly(3-hydroxyalkanoate)-based resin component, the proportion of the copolymer (A) is 40 to 90% by weight, and the proportion of the copolymer (B) is 10 to 60% by weight, The present invention relates to a blow or injection molded article, wherein the 50% breaking energy of the molded article measured by the DuPont impact test is 0.3 J or more. Preferably, the average content of the other hydroxyalkanoate units in all monomer units constituting the poly(3-hydroxyalkanoate) resin component is 7 to 19 mol %. Preferably, the other hydroxyalkanoate units are 3-hydroxyhexanoate units. The blow or injection molded article may further contain a crystal nucleating agent and / or a lubricant. The blow or injection molded article may further contain 1 part by weight to 30 parts by weight of an inorganic filler relative to 100 parts by weight of the poly(3-hydroxyalkanoate) resin component. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a blow-molded or injection-molded article that contains a poly(3-hydroxyalkanoate)-based resin component and has good moldability and excellent impact resistance. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0012] One embodiment of the present invention relates to a blow-molded or injection-molded article containing a poly(3-hydroxyalkanoate)-based resin component.

[0013] (Poly(3-hydroxyalkanoate) resin component) The poly(3-hydroxyalkanoate) resin component is a mixture of at least two poly(3-hydroxyalkanoate) resins having different content ratios of constituent monomers. By using this mixture, it is possible to provide a blow-molded or injection-molded article with good moldability and excellent impact resistance.

[0014] The poly(3-hydroxyalkanoate) resin is preferably a polymer having a 3-hydroxyalkanoate unit, specifically a polymer containing a unit represented by the following general formula (1). [-CHR-CH2-CO-O-] (1)

[0015] 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.

[0016] The poly(3-hydroxyalkanoate) resin is preferably a poly(3-hydroxyalkanoate) resin produced by a microorganism, in which all 3-hydroxyalkanoate units are contained as (R)-3-hydroxyalkanoate units.

[0017] The poly(3-hydroxyalkanoate) resin 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. The poly(3-hydroxyalkanoate) resin may contain only one or more types of 3-hydroxyalkanoate units as structural units of the polymer, or may contain one or more types of 3-hydroxyalkanoate units as well as other units (e.g., 4-hydroxyalkanoate units).

[0018] The poly(3-hydroxyalkanoate) resin may be a homopolymer or copolymer containing 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) units. In particular, it is preferable that all 3-hydroxybutyrate units are (R)-3-hydroxybutyrate units. Furthermore, it is preferable that the poly(3-hydroxyalkanoate) resin is a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units.

[0019] Specific examples of poly(3-hydroxyalkanoate) resins include poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviation: P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-3-hydroxyhexanoate), and 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), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviation: P3HB4HB), etc. In particular, from the viewpoints of moldability and mechanical properties of blow-molded or injection-molded articles, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is preferred, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is more preferred.

[0020] The poly(3-hydroxyalkanoate) resin component contains at least one highly crystalline poly(3-hydroxyalkanoate) resin and at least one low-crystalline poly(3-hydroxyalkanoate) resin. Generally, highly crystalline poly(3-hydroxyalkanoate) resins have excellent moldability but poor mechanical strength, while low-crystalline poly(3-hydroxyalkanoate) resins have poor moldability but excellent mechanical properties. It is believed that when the two resins are mixed, the highly crystalline poly(3-hydroxyalkanoate) resin forms fine resin crystal particles, while the low-crystalline poly(3-hydroxyalkanoate) resin forms tie molecules that crosslink the resin crystal particles. Using these resins in combination can significantly improve the impact resistance of blow-molded or injection-molded articles while maintaining good moldability.

[0021] The highly crystalline poly(3-hydroxyalkanoate) resin is a copolymer (A) of 3-hydroxybutyrate units and other hydroxyalkanoate units. The content of 3-hydroxybutyrate units in the highly crystalline poly(3-hydroxyalkanoate) resin is preferably higher than the average content of 3-hydroxybutyrate units in all monomer units constituting the poly(3-hydroxyalkanoate) resin component. Specifically, the content of other hydroxyalkanoate units in the highly crystalline resin (A) is preferably 1 to 6 mol%, more preferably 2 to 5 mol%, and even more preferably 3 to 5 mol%.

[0022] The highly crystalline poly(3-hydroxyalkanoate) resin (A) may be any of the copolymers containing 3-hydroxybutyrate units described above, but poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is preferred, with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) being more preferred.

[0023] The low-crystalline poly(3-hydroxyalkanoate) resin is a copolymer (B) of 3-hydroxybutyrate units and other hydroxyalkanoate units. The content of 3-hydroxybutyrate units in the low-crystalline poly(3-hydroxyalkanoate) resin is preferably lower than the average content of 3-hydroxybutyrate units in all monomer units constituting the poly(3-hydroxyalkanoate) resin component. Specifically, the content of other hydroxyalkanoate units in the low-crystalline resin (B) is preferably 24 to 99 mol%, more preferably 24 to 50 mol%, even more preferably 24 to 35 mol%, and particularly preferably 24 to 30 mol%.

[0024] The low-crystalline poly(3-hydroxyalkanoate) resin (B) may be any of the copolymers containing 3-hydroxybutyrate units described above, but poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is preferred, with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) being more preferred.

[0025] The proportion of each resin used relative to the total amount of the highly crystalline poly(3-hydroxyalkanoate) resin (A) and the low crystalline poly(3-hydroxyalkanoate) resin (B) is preferably 40% by weight or more and 90% by weight or less, and 10% by weight or more and 60% by weight or less, from the viewpoints of the impact resistance, moldability, and handleability of the molded article, of the resin (A), more preferably 45% by weight or more and 85% by weight or less, and 15% by weight or more and 55% by weight or less, even more preferably 50% by weight or more and 80% by weight or less, and 20% by weight or more and 50% by weight or less, even more preferably 55% by weight or more and 75% by weight or less, and 25% by weight or more and 45% by weight or less, and particularly preferably 60% by weight or more and 70% by weight or less, and 30% by weight or more and 40% by weight or less.

[0026] The poly(3-hydroxyalkanoate) resin component may contain only the highly crystalline resin (A) and the low-crystalline resin (B), or may further contain another poly(3-hydroxyalkanoate) resin. The other poly(3-hydroxyalkanoate) resin may be a homopolymer of 3-hydroxybutyrate, or may be a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which does not fall within the definition of either resin (A) or resin (B).

[0027] From the viewpoint of achieving both impact resistance and moldability of the molded article, the average content ratio of 3-hydroxybutyrate units and other hydroxyalkanoate units in all monomer units constituting the poly(3-hydroxyalkanoate) resin component is preferably 3-hydroxybutyrate units / other hydroxyalkanoate units = 93 / 7 to 81 / 19 (mol % / mol %), more preferably 93 / 7 to 83 / 17 (mol % / mol %), even more preferably 92 / 8 to 84 / 16 (mol % / mol %), and particularly preferably 91 / 9 to 85 / 15 (mol % / mol %).

[0028] The average content ratio of each monomer unit to all monomer units constituting the poly(3-hydroxyalkanoate)-based resin component can be determined by a method known to those skilled in the art, for example, the method described in paragraph

[0047] of WO 2013 / 147139. The average content ratio means the molar ratio of each monomer unit to all monomer units in the entire poly(3-hydroxyalkanoate)-based resin component, and refers to the molar ratio of each monomer unit contained in the entire mixture of two or more poly(3-hydroxyalkanoate)-based resins constituting the poly(3-hydroxyalkanoate)-based resin component.

[0029] The weight average molecular weight of the poly(3-hydroxyalkanoate) resin component is not particularly limited, but from the viewpoint of achieving both impact resistance and moldability of the molded article, it is preferably 200,000 to 2,000,000, more preferably 250,000 to 1,500,000, and even more preferably 300,000 to 1,000,000.

[0030] The weight-average molecular weight of each poly(3-hydroxyalkanoate) resin constituting the poly(3-hydroxyalkanoate) resin component is not particularly limited. However, from the viewpoint of achieving both impact resistance and moldability of the molded article, the weight-average molecular weight of the highly crystalline poly(3-hydroxyalkanoate) resin is preferably 200,000 to 1,000,000, more preferably 220,000 to 800,000, and even more preferably 250,000 to 600,000. On the other hand, from the viewpoint of achieving both impact resistance and moldability of the molded article, the weight-average molecular weight of the low-crystalline poly(3-hydroxyalkanoate) resin is preferably 200,000 to 2,500,000, more preferably 250,000 to 2,300,000, and even more preferably 300,000 to 2,000,000.

[0031] The weight-average molecular weight of the poly(3-hydroxyalkanoate) resin or poly(3-hydroxyalkanoate) resin component can be measured in terms of polystyrene using gel permeation chromatography (HPLC GPC system manufactured by Shimadzu Corporation) using a chloroform solution. As the column for the gel permeation chromatography, a column appropriate for measuring the weight-average molecular weight may be used.

[0032] The poly(3-hydroxyalkanoate) resin component is preferably one that has not been crosslinked using a crosslinking agent such as an organic peroxide, that is, a resin component that does not have a crosslinked structure.

[0033] The method for producing poly(3-hydroxyalkanoate) resins is not particularly limited, and may be a production method using chemical synthesis or a production method using a microorganism. Among these, a production method using a microorganism is preferred. Known methods can be applied to the production method using a microorganism. For example, known bacteria that produce copolymers of 3-hydroxybutyrate and other hydroxyalkanoates include Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes eutrophus, which produces P3HB4HB. In particular, for P3HB3HH, to increase productivity of P3HB3HH, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)) or the like, into which genes encoding P3HA synthases have been introduced, is preferred. Microbial cells obtained by culturing these microorganisms under appropriate conditions and allowing P3HB3HH to accumulate within the cells, can be used. Alternatively, genetically modified microorganisms into which various poly(3-hydroxyalkanoate) resin synthesis-related genes have been introduced may be used depending on the poly(3-hydroxyalkanoate) resin to be produced, or the culture conditions, including the type of substrate, may be optimized.

[0034] The method for obtaining a blend of two or more poly(3-hydroxyalkanoate) resins is not particularly limited, and may be a method of obtaining a blend by microbial production or a method of obtaining a blend by chemical synthesis. Alternatively, a blend may be obtained by melt-kneading two or more resins using an extruder, kneader, Banbury mixer, roll, or the like, or by dissolving two or more resins in a solvent, mixing, and drying the resins.

[0035] (other resins) The blow-molded or injection-molded article according to one embodiment may contain resins other than the poly(3-hydroxyalkanoate)-based resin, provided that the effects of the invention are not impaired. Examples of such resins include aliphatic polyester-based resins such as polybutylene succinate adipate, polybutylene succinate, polycaprolactone, and polylactic acid, and aliphatic aromatic polyester-based resins such as polybutylene adipate terephthalate, polybutylene sebacate terephthalate, and polybutylene azelate terephthalate. Only one type of other resin may be contained, or two or more types may be contained.

[0036] The content of the other resin is not particularly limited, but is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 10 parts by weight or less, relative to 100 parts by weight of the total poly(3-hydroxyalkanoate) resin component. The lower limit of the content of the other resin is not particularly limited, and may be 0 part by weight.

[0037] (inorganic filler) The blow molded article or injection molded article according to one embodiment preferably contains an inorganic filler from the viewpoint of improving the strength of the molded article.

[0038] The inorganic filler is not particularly limited as long as it is an inorganic filler that can be added to a resin material for blow molding or injection molding, and examples thereof include silica-based inorganic fillers such as quartz, fumed silica, silicic anhydride, fused silica, crystalline silica, amorphous silica, fillers formed by condensing alkoxysilanes, and ultrafine amorphous silica, as well as alumina, zircon, iron oxide, zinc oxide, titanium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, glass, silicone rubber, silicone resin, titanium oxide, carbon fiber, mica, graphite, carbon black, ferrite, graphite, diatomaceous earth, clay, talc, calcium carbonate, manganese carbonate, magnesium carbonate, barium sulfate, and silver powder. These may be used alone or in combination of two or more.

[0039] The inorganic filler may be surface-treated to improve dispersibility in the resin material. Examples of the surface treatment agent include higher fatty acids, silane coupling agents, titanate coupling agents, sol-gel coating agents, and resin coating agents.

[0040] The water content of the inorganic filler is preferably 0.01 to 10% by weight, more preferably 0.01 to 5% by weight, and even more preferably 0.01 to 1% by weight, because this easily inhibits hydrolysis of the poly(3-hydroxyalkanoate) resin. The water content can be determined in accordance with JIS-K5101.

[0041] The average particle size of the inorganic filler is preferably 0.1 to 100 μm, more preferably 0.1 to 50 μm, in order to provide excellent mechanical properties and moldability of the molded body. The average particle size can be measured using a laser diffraction / scattering device such as the "Microtrac MT3100II" manufactured by Nikkiso Co., Ltd.

[0042] Among inorganic fillers, silica is preferred because it can improve the mechanical properties of the molded body.The type of silica is not particularly limited, but from the viewpoint of versatility, synthetic amorphous silica produced by a dry method or a wet method is preferred.In addition, either hydrophobic or non-hydrophobic treated silica can be used, and one type can be used alone or two or more types can be used in combination.

[0043] The amount of the inorganic filler to be added is not particularly limited, but may be 0 to 40 parts by weight per 100 parts by weight of the poly(3-hydroxyalkanoate) resin component. Although the inorganic filler need not be added, adding an inorganic filler has the advantage of improving the strength of the molded body. When an inorganic filler is added, the amount is preferably 1 to 40 parts by weight, more preferably 5 to 35 parts by weight, and even more preferably 10 to 30 parts by weight.

[0044] For the purpose of improving the dispersibility of the silica, it is preferable to use a dispersing aid in combination with the silica.

[0045] Examples of the dispersing aid include glycerin ester compounds, adipate compounds, polyether ester compounds, phthalate ester compounds, isosorbide ester compounds, and polycaprolactone compounds. Among these, modified glycerin compounds such as glycerin diacetomonolaurate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate are preferred because they have excellent affinity with resin components and are less likely to bleed; adipate compounds such as diethylhexyl adipate, dioctyl adipate, and diisononyl adipate; and polyether ester compounds such as polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate. Furthermore, those containing a large amount of biomass-derived components are particularly preferred because they can increase the biomass content of the entire composition. Examples of such dispersing aids include Riken Vitamin Co., Ltd.'s "Rikemal" (registered trademark) PL series and ROQUETTE's Polysorb series. The dispersing aids can be used singly or in combination of two or more.

[0046] The amount of the dispersing aid (total amount) is not particularly limited, but is preferably 0.1 to 20 parts by weight per 100 parts by weight of the poly(3-hydroxyalkanoate) resin components in total. However, the dispersing aid does not necessarily have to be added.

[0047] (additives) The blow molded article or injection molded article according to one embodiment may contain additives to the extent that the effects of the invention are not impaired. Examples of additives that can be used depending on the purpose include nucleating agents, lubricants, plasticizers, antistatic agents, flame retardants, conductive agents, heat insulating agents, crosslinking agents, antioxidants, UV absorbers, colorants, inorganic fillers, organic fillers, and hydrolysis inhibitors. Biodegradable additives are particularly preferred.

[0048] Examples of nucleating agents include pentaerythritol, orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, and boron nitride. Among these, pentaerythritol is preferred because of its particularly excellent effect of promoting crystallization of the poly(3-hydroxyalkanoate)-based resin component. The amount of nucleating agent used is not particularly limited, but is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, and even more preferably 0.7 to 1.5 parts by weight, per 100 parts by weight of the poly(3-hydroxyalkanoate)-based resin component. One or more types of nucleating agents may be used, and the ratio of use can be adjusted appropriately depending on the purpose.

[0049] Examples of lubricants include behenamide, oleamide, erucamide, stearamide, palmitamide, N-stearylbehenamide, N-stearylerucamide, ethylenebisstearamide, ethylenebisoleamide, ethylenebiserucamide, ethylenebislauricamide, ethylenebiscapricamide, p-phenylenebisstearamide, and polycondensates of ethylenediamine, stearic acid, and sebacic acid. Among these, behenamide and erucamide are preferred because of their particularly excellent lubricating effect on poly(3-hydroxyalkanoate)-based resin components. The amount of lubricant used is not particularly limited, but is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, and even more preferably 0.1 to 1.5 parts by weight, per 100 parts by weight of the poly(3-hydroxyalkanoate)-based resin components. Furthermore, one type of lubricant may be used, or two or more types may be used, and the ratio of use can be adjusted appropriately depending on the purpose.

[0050] Examples of plasticizers include glycerin ester compounds, citrate ester compounds, sebacate compounds, adipate compounds, polyether ester compounds, benzoate ester compounds, phthalate ester compounds, isosorbide ester compounds, polycaprolactone compounds, and dibasic acid ester compounds. Among these, glycerin ester compounds, citrate ester compounds, sebacate compounds, and dibasic acid ester compounds are preferred because of their particularly excellent plasticizing effect on poly(3-hydroxyalkanoate) resin components. Examples of glycerin ester compounds include glycerin diacetomonolaurate. Examples of citrate ester compounds include acetyl tributyl citrate. Examples of sebacate ester compounds include dibutyl sebacate. Examples of dibasic acid ester compounds include benzyl methyl diethylene glycol adipate. The amount of plasticizer used is not particularly limited, but is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, and even more preferably 3 to 10 parts by weight, per 100 parts by weight of the poly(3-hydroxyalkanoate) resin component in total. One type of plasticizer may be used, or two or more types may be used, and the usage ratio can be adjusted appropriately depending on the purpose.

[0051] The blow-molded or injection-molded article according to one embodiment has excellent impact resistance. From this perspective, the 50% breaking energy of the molded article, measured by the DuPont impact test, is preferably 0.3 J or more, more preferably 0.5 J or more, and even more preferably 1 J or more. A molded article satisfying the 50% breaking energy requirement can be obtained by mixing at least two types of poly(3-hydroxyalkanoate) resins having different content ratios of the aforementioned constituent monomers. Details of the method for measuring the 50% breaking energy are described in the Examples section. The 50% fracture energy of the blow molded article or injection molded article may be a value measured on a test piece prepared as described in the Examples section using resin pellets for producing the blow molded article or injection molded article according to the embodiment, or a value measured on a test piece prepared by cutting out a part of the blow molded article or injection molded article according to the embodiment.

[0052] The blow molded article or injection molded article according to one embodiment preferably exhibits a flexural modulus of 500 MPa or more. A molded article with a flexural modulus of 500 MPa or more has appropriate hardness and is easy to handle. A flexural modulus of 550 MPa or more is more preferable. A molded article exhibiting such a flexural modulus can be obtained by adjusting the blending ratio of the high-crystalline poly(3-hydroxyalkanoate) resin and the low-crystalline poly(3-hydroxyalkanoate) resin. Details of the method for measuring the flexural modulus are described in the Examples section. The flexural modulus of the blow molded article or injection molded article may be a value measured on a test piece prepared as described in the Examples section using resin pellets for producing the blow molded article or injection molded article according to the embodiment, or a value measured on a test piece prepared by cutting out a part of the blow molded article or injection molded article according to the embodiment.

[0053] (Method for manufacturing blow molded or injection molded articles) The blow molded article or injection molded article according to one embodiment can be produced by a known blow molding method or injection molding method after obtaining pellets as needed.

[0054] First, a poly(3-hydroxyalkanoate)-based resin component, and optional components as needed, are added and melt-kneaded using an extruder, kneader, Banbury mixer, roll, or the like to produce a resin composition, which is then extruded into strands and cut to obtain pellets with particle shapes such as cylindrical, elliptical, spherical, cubic, rectangular, etc. The produced pellets are then thoroughly dried at 40 to 80°C to remove moisture, and are then preferably subjected to blow molding or injection molding.

[0055] The temperature at which the melt-kneading is carried out cannot be generally defined because it depends on the melting point, melt viscosity, etc. of the resin used, but the resin temperature of the melt-kneaded product at the die outlet is preferably 150 to 200° C., more preferably 155 to 195° C., and even more preferably 160 to 190° C. If the resin temperature of the melt-kneaded product is less than 150° C., the poly(3-hydroxyalkanoate) resin component may remain unmelted, and if it exceeds 200° C., the poly(3-hydroxyalkanoate) resin component may undergo thermal decomposition.

[0056] The pellets thus prepared can then be subjected to blow molding or injection molding to form a blow molded or injection molded article. Blow molding is a molding method that can produce hollow molded articles such as bottles by blowing air into a plasticized resin material. Any of extrusion blow molding, multilayer extrusion blow molding, injection blow molding, stretch blow molding, etc. can be used.

[0057] Injection molding is a method in which a heated and melted resin composition is injected into a mold, the resin composition is cooled and solidified in the mold, the mold is opened, and the molded article is demolded to obtain a molded article. Injection molding methods that can be used include injection molding methods commonly used when molding thermoplastic resins, as well as gas-assisted molding, injection compression molding, and other injection molding methods. Other methods that can be used include in-mold molding, gas press molding, two-color molding, sandwich molding, push-pull molding, and scorim molding. However, usable injection molding methods are not limited to the above methods.

[0058] The uses of the blow molded article or injection molded article according to one embodiment are not particularly limited, but examples include bottles, containers, cases for beverages, liquid foods, liquid detergents, etc., toys, entertainment items, tableware, agricultural materials, office automation parts, home appliance parts, body parts for ships and aircraft, automobile components, daily necessities, stationery products, etc. [Example]

[0059] The present invention will be specifically explained below with reference to examples, but the technical scope of the present invention is not limited to these examples.

[0060] The substances used in the examples and comparative examples are shown below. [Poly(3-hydroxyalkanoate) resin] P3HB3HH-1: P3HB3HH (average content ratio of 3HB / 3HH = 95.4 / 4.6 (mol% / mol%), weight average molecular weight is 660,000 g / mol) It was produced in accordance with the method described in Example 2 of WO 2019 / 142845. P3HB3HH-2: P3HB3HH (average content ratio of 3HB / 3HH = 71.8 / 28.2 (mol% / mol%), weight average molecular weight is 660,000 g / mol) Produced in accordance with the method described in Example 9 of WO 2019 / 142845. P3HB3HH-3: X151A (Kaneka Biodegradable Polymer PHBH (registered trademark)) (average content ratio of 3HB / 3HH = 89 / 11 (mol% / mol%), weight average molecular weight is 600,000 g / mol) P3HB3HH-4: X131A (Kaneka Biodegradable Polymer PHBH (registered trademark)) (average content ratio of 3HB / 3HH = 94 / 6 (mol% / mol%), weight average molecular weight is 600,000 g / mol) P3HB3HH-5: P3HB3HH (average content ratio of 3HB / 3HH = 83.0 / 17.0 (mol% / mol%), weight average molecular weight is 590,000 g / mol) Produced in accordance with the method described in Example 7 of WO 2019 / 142845.

[0061] When a mixture of two or more poly(3-hydroxyalkanoate) resins is used as the poly(3-hydroxyalkanoate) resin component, the average HH ratio in Table 1 is the average value calculated from the HH ratio in each poly(3-hydroxyalkanoate) resin and the weight ratio of each poly(3-hydroxyalkanoate) resin.

[0062] [Additives] Additive-1: Pentaerythritol (Mitsubishi Chemical Corporation: Neuraizer P) Additive-2: Behenamide (Nippon Fine Chemical Co., Ltd.: BNT-22H) Additive 3: Erucic acid amide (Neutron-S, manufactured by Nippon Fine Chemical Co., Ltd.) The evaluation methods used in the examples and comparative examples are described below.

[0063] [Evaluation of 50% fracture energy by DuPont impact test] (Preparation of test specimens) Resin pellets dried at 60°C for 3 hours were injection molded using an injection molding machine (Toyo Seiki Kinzoku Co., Ltd.: CH150B) under the following conditions: cylinder temperature H1 = 160°C, H2 = 150°C, H3 = 140°C, nozzle temperature 160°C, mold temperature 45°C, and cooling time 30 seconds to obtain a molded body (80 mm × 80 mm × 1 mm).The molded body was then divided into four to obtain 40 mm × 40 mm × 1 mm test pieces.

[0064] (50% fracture energy evaluation) The test specimens were cured for 7 days in a constant temperature room at 25°C and then measured using a DuPont drop impact tester (manufactured by Toyo Seiki Seisakusho) in accordance with ASTM D 2794 (test specimen thickness: 1.0 mm, weight of iron ball: 0.3 to 2.0 kg, radius of impact point: 7.9 mm, measurement temperature: 25°C, number of measurements: 20, unit: J). The 50% breaking height was measured and the 50% breaking energy was calculated from this value. The higher the 50% breaking energy, the better the impact resistance, and it is an index of impact resistance. Note that when the measured 50% breaking energy exceeded 19.8 J, it was recorded as ">19.8 J."

[0065] [Bottle drop test and bottle moldability evaluation] (Bottle manufacturing using a blow molding machine) The cylinder temperature of a 40mm single-screw extruder was set to 150°C and the die temperature to 160°C. Resin pellets were added and melted, then extruded downward through the annular die into a tubular shape (parison). The parison was then clamped on both sides between molds located 20cm below the die to pinch off and fuse the bottom of the parison. Air was then blown into the inside of the parison, one end of which was closed, to form the parison, which was then cooled and solidified, resulting in a bottle container with an opening at the top, an outer diameter of 60mm, and a height of 14cm.

[0066] (Bottle drop test) The bottles were filled with 380 ml of water, capped, and dropped from a height of 1.5 m with the bottom of the container facing downwards. If the bottles did not break, they were marked with an O; if they did break, they were marked with an X. If they cracked, they were marked with a △.

[0067] (bottle molding ability) In the above-mentioned bottle production, when the parison was cooled and solidified within 30 seconds, it was marked as "good", and when it took 31 seconds or more, it was marked as "bad".

[0068] [Evaluation of flexural modulus] (Preparation of test specimens) The resin pellets were dried at 60°C for 3 hours and then injection-molded using an injection molding machine (Toyo Seiki Kinzoku Co., Ltd.: CH150B) under the following conditions: cylinder temperature H1 = 160°C, H2 = 150°C, H3 = 140°C, nozzle temperature 160°C, mold temperature 45°C, and cooling time 30 seconds, to obtain a molded body (80 mm × 10 mm × 4 mm).

[0069] (Evaluation of flexural modulus) The flexural modulus was evaluated in accordance with JIS-K7171 using a three-point bending tester (Autograph AG-10TB, manufactured by Shimadzu Corporation). The test conditions were a test speed of 2 mm / min, a distance between support stands of 64 mm, and radii of the indenter and support stand of 5.0 mm. The measurement atmosphere was 23°C and 50% RH.

[0070] Example 1 2.25 kg of P3HB3HH-1 and 2.75 kg of P3HB3HH-2 were blended to obtain the resin composition shown in Table 1, and then 50 g of additive-1, 25 g of additive-2, and 25 g of additive-3 were dry-blended. The resulting resin material (resin mixture) was fed into a φ26 mm co-rotating twin-screw extruder with a cylinder temperature set to 150°C and a die temperature set to 150°C, and extruded. The extruded resin material was passed through a water tank filled with hot water at 40°C to solidify the strands, which were then cut using a pelletizer to obtain resin composition pellets.

[0071] Test pieces for DuPont impact testing and flexural modulus evaluation were prepared from the obtained pellets using an injection molding machine. The 50% fracture energy was measured to be 19.8 J or more, and the flexural modulus was measured to be 422 MPa. Similarly, bottles were produced from the obtained pellets using a blow molding machine, and a bottle moldability evaluation and a bottle drop test were carried out. The bottle moldability was rated as "good," and the bottle did not break in the drop test, so the result was also "good." The results are summarized in Table 1.

[0072] (Examples 2 to 7, Comparative Examples 1 to 5) Resin composition pellets were prepared in the same manner as in Example 1 except that the resin formulation was changed as shown in Table 1, and evaluations were carried out in the same manner as in Example 1. The results are summarized in Table 1.

[0073] [Table 1]

[0074] The following can be seen from Table 1: Examples 1 to 7 use a combination of 45 to 85% by weight of a highly crystalline poly(3-hydroxyalkanoate) resin and 15 to 55% by weight of a low-crystalline poly(3-hydroxyalkanoate) resin, and have good moldability. The resulting molded articles have a 50% fracture energy of 0.3 J or more in the DuPont impact test and also show good results in the bottle drop test, demonstrating excellent impact resistance. Among them, the molded articles obtained in Examples 3 to 7 exhibited a flexural modulus of 500 MPa or more, and the molded articles had good handling properties.

[0075] On the other hand, the molded articles obtained in Comparative Examples 1 to 3 and 5 had a 50% breaking energy of less than 0.3 J in the DuPont impact test and also showed poor results in the bottle drop test, indicating insufficient impact resistance.Comparative Example 4 had poor bottle moldability, and a molded article could not be produced.

Claims

1. A blow-molded article containing a poly(3-hydroxyalkanoate)-based resin component, the poly(3-hydroxyalkanoate) resin component comprises a copolymer (A) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 1 to 6 mol %, and a copolymer (B) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 24 mol % or more; the other hydroxyalkanoate units are 3-hydroxyhexanoate units; In the poly(3-hydroxyalkanoate)-based resin component, the proportion of the copolymer (A) is 40 to 90% by weight, and the proportion of the copolymer (B) is 10 to 60% by weight, A blow-molded article, wherein the 50% fracture energy of the molded article measured by a DuPont impact test is 0.3 J or more and 19.8 J or less.

2. 2. The blow molded article according to claim 1, wherein the average content of the other hydroxyalkanoate units in all monomer units constituting the poly(3-hydroxyalkanoate) resin component is 7 to 19 mol %.

3. The blow-molded article according to claim 1 or 2, further comprising a crystal nucleating agent and / or a lubricant.

4. The blow molded article according to any one of claims 1 to 3, further comprising 1 part by weight or more and 30 parts by weight or less of an inorganic filler per 100 parts by weight of the poly(3-hydroxyalkanoate)-based resin component.

Images