Method for producing composition for thermal processing

Abstract

To provide a method for producing a composition for thermal processing that contains a poly(3-hydroxyalkanoate)-based resin, the composition exhibiting favorable solidification property during thermal processing, allowing production with high productivity, and enabling reduction of poor mixing of resin components.SOLUTION: A composition for thermal processing is obtained by subjecting a raw material composition containing a poly(3-hydroxyalkanoate)-based resin to melting, followed by cooling and solidification. The raw material composition comprises a resin component (I) that, in differential scanning calorimetry, exhibits a melting point peak (i) with a peak temperature of 165°C or more, and a resin component (II) that does not exhibit the melting point peak (i), and the resin component (I) includes a melt-kneaded material derived from a poly(3-hydroxyalkanoate)-based copolymer (A) and poly(3-hydroxybutyrate) (B). The melting of the raw material composition is performed under a condition such that the maximum temperature of the raw material composition is at or below the end temperature of the melting point peak (i).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a thermally processable composition containing a poly(3-hydroxyalkanoate) resin. [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 a desire to develop plastics that can decompose 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] However, poly(3-hydroxyalkanoate) resins have a slow crystallization rate, so after the resin is heated and melted during molding processing, it takes time for it to crystallize and solidify, which presents a problem of low productivity for molded bodies produced by melt processing.

[0005] As one method for addressing such problems, for example, Patent Document 1 describes that a melt-processable composition with excellent solidification properties can be produced by heating and extruding a poly(3-hydroxybutyrate) resin having a broad melting point peak under conditions of not less than the melting point peak temperature and not more than the end temperature of the melting point peak.

[0006] Patent Document 2 discloses that the crystallization rate of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) can be increased by blending 0.1 to 20 parts by weight of poly(3-hydroxyalkanoate) of a specific particle size having a melting point 20°C or more higher than that of the resin with 100 parts by weight of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2021 / 010327 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-161802 Summary of the Invention [Problem to be solved by the invention]

[0008] The technology disclosed in Patent Document 1 makes it possible to obtain a melt-processable composition having a new crystallization peak at a higher temperature than the melting peak of the raw resin. By forming such a high-melting peak, it is possible to improve the solidification property during melt processing.

[0009] However, although the technique disclosed in Patent Document 1 can produce a composition with improved solidification properties during melt processing, it is necessary to ensure a long residence time in the extruder in order to form a high-melting peak, which tends to reduce the productivity of the melt-processable composition.

[0010] The technology described in Patent Document 2 discloses that blending a high-melting-point poly(3-hydroxyalkanoate) resin with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) can increase the crystallization rate of the latter. However, this technology does not sufficiently improve solidification properties, and there are cases where the two resin components are not mixed well, resulting in poor mixing.

[0011] In view of the above-described current situation, the present invention aims to provide a method for producing a poly(3-hydroxyalkanoate)-based resin-containing thermal processing composition that exhibits good solidification properties during thermal processing, which can be produced with good productivity and can suppress poor mixing of the resin components. [Means for solving the problem]

[0012] As a result of intensive research conducted by the inventors to solve the above-mentioned problems, they discovered that when producing a heat-processable composition containing a poly(3-hydroxyalkanoate)-based resin, by using, as the raw material composition, a resin component that exhibits a high-melting peak and contains a molten blend of two specific types of resins in combination with a resin component that does not have a high-melting peak, and by melting the raw material composition under conditions that result in a temperature below the end temperature of the melting peak, it is possible to produce a heat-processable composition containing a poly(3-hydroxyalkanoate)-based resin that solidifies well during heat processing with good productivity and to suppress poor mixing of the resin components, thereby completing the present invention.

[0013] That is, the present invention provides a method for producing a thermal processing composition containing a poly(3-hydroxyalkanoate) resin, comprising: The method includes a step of melting a raw material composition containing a poly(3-hydroxyalkanoate) resin, followed by cooling and solidifying the raw material composition to obtain a composition for thermal processing, the raw material composition comprises a resin component (I) having a melting point peak (i) whose peak temperature is 165°C or higher in differential scanning calorimetry analysis, and a resin component (II) not having the melting point peak (i); The resin component (I) contains a melt-kneaded product of a poly(3-hydroxyalkanoate) copolymer (A) and a poly(3-hydroxybutyrate) (B), The method for producing a composition for thermal processing relates to the method for producing a composition for thermal processing, wherein the raw material composition is melted under conditions in which the maximum temperature of the raw material composition is equal to or lower than the end temperature of the melting point peak (i). The present invention also relates to a method for producing a molded article containing a poly(3-hydroxyalkanoate) resin, which includes a step of obtaining a composition for thermal processing by the above-mentioned production method, and then thermally processing the composition for thermal processing to produce a molded article. [Effects of the Invention]

[0014] The present invention aims to provide a method for producing a poly(3-hydroxyalkanoate)-based resin-containing thermal processing composition that exhibits good solidification properties during thermal processing, with high productivity, and that can suppress insufficient mixing of the resin components. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. The present embodiment relates to a method for producing a thermal processing composition containing a poly(3-hydroxyalkanoate) resin, which includes a step of melting a raw material composition containing a poly(3-hydroxyalkanoate) resin, followed by cooling and solidifying the composition to obtain a thermal processing composition.

[0016] [Poly(3-hydroxyalkanoate) resin] First, the poly(3-hydroxyalkanoate) resin will be described. Poly(3-hydroxyalkanoate) resin (hereinafter also referred to as P3HA) is a general term for polymers containing at least 3-hydroxyalkanoic acid as a monomer unit. The 3-hydroxyalkanoic acid constituting P3HA is not particularly limited, but examples include 3-hydroxybutanoic acid, 3-hydroxypropionic acid, 3-hydroxypentanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, and 3-hydroxyoctanoic acid. P3HA may be a homopolymer or a copolymer containing two or more types of monomer units.

[0017] Furthermore, P3HA may be a copolymer containing, as a monomer unit, at least one of the above-mentioned 3-hydroxyalkanoic acids, as well as other hydroxyalkanoic acids (for example, 4-hydroxyalkanoic acids such as 4-hydroxybutanoic acid). Only one type of P3HA may be used, or two or more types may be used in combination, but a combination of two or more types is preferred.

[0018] A raw material composition containing P3HA, or a composition for thermal processing or a molded article produced according to the present disclosure preferably contains 50% by weight or more of P3HA, more preferably 70% by weight or more, even more preferably 80% by weight or more, and even more preferably 90% by weight or more. By using P3HA as the main component, good biodegradability can be exhibited.

[0019] In this embodiment, the raw material composition containing P3HA includes at least a resin component (I) and a resin component (II). The resin component (I) contains a melt-kneaded mixture of a poly(3-hydroxyalkanoate) copolymer (A) and a poly(3-hydroxybutyrate) (B).

[0020] [Poly(3-hydroxyalkanoate) copolymer (A)] The poly(3-hydroxyalkanoate) copolymer is a copolymer having at least one or more types of 3-hydroxyalkanoate units. The 3-hydroxyalkanoate unit is preferably represented by the following general formula (1). [-CHR-CH2-CO-O-] (1)

[0021] In the general formula (1), R is C p H 2p+1 where 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.

[0022] 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.

[0023] 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 (A) 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.

[0024] 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.

[0025] 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.

[0026] 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 below. In particular, from the viewpoints of productivity and mechanical properties, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is preferred, with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) being particularly preferred.

[0027] From the viewpoint of the balance between productivity and mechanical properties, the poly(3-hydroxyalkanoate) copolymer (A) preferably contains at least two types of poly(3-hydroxyalkanoate) copolymers differing from each other in crystallinity, and more preferably contains at least two types of poly(3-hydroxyalkanoate) copolymers differing from each other in the types of constituent monomers and / or the content ratios of the constituent monomers.

[0028] Specifically, the poly(3-hydroxyalkanoate) copolymer (A) preferably contains a copolymer (A1) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 1 to 5 mol %, and a copolymer (A2) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 24 mol % or more. Such a resin composition can achieve a good balance between productivity and mechanical properties.

[0029] In addition to the copolymer (A1) and the copolymer (A2), it is preferable to further contain a copolymer (A3) of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of other hydroxyalkanoate units is 6 mol % or more but less than 24 mol %, which can improve the balance between productivity and mechanical properties.

[0030] Copolymer (A1) is a highly crystalline P3HA, while copolymer (A2) is a low-crystalline P3HA. Copolymer (A3) is a medium-crystalline P3HA whose crystallinity is intermediate between that of copolymer (A1) and copolymer (A2).

[0031] Generally, highly crystalline P3HA has excellent productivity but poor mechanical properties, while low-crystalline P3HA has poor productivity but excellent mechanical properties. By using a combination of two or three of the above-mentioned resins, a good balance between productivity and mechanical properties can be achieved.

[0032] The content of other hydroxyalkanoate units in the copolymer (A1) is 1 mol % or more and 5 mol % or less. From the viewpoint of productivity, the lower limit of this ratio is preferably 2 mol % or more, and the upper limit is preferably 4 mol % or less.

[0033] The copolymer (A1) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0034] The content of other hydroxyalkanoate units in copolymer (A2) is 24 mol% or more. From the viewpoint of mechanical properties, the lower limit of this ratio is preferably 26 mol% or more, more preferably 28 mol% or more. From the viewpoint of productivity of copolymer (A2), the upper limit of this ratio is preferably 99 mol% or less, more preferably 50 mol% or less, even more preferably 40 mol% or less, and particularly preferably 30 mol% or less.

[0035] The copolymer (A2) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0036] The proportions of copolymer (A1) and copolymer (A2) used are not particularly limited, but from the viewpoints of the productivity of copolymer (A2) and the balance between productivity and mechanical properties, the weight ratio of copolymer (A1) to copolymer (A2) is preferably 1.5 to 4.5. The lower limit of this weight ratio is preferably 2.0 or more. The upper limit is preferably 4.0 or less, more preferably 3.5 or less.

[0037] The content of other hydroxyalkanoate units in the copolymer (A3) is 6 mol% or more and less than 24 mol%. From the viewpoint of productivity, the upper limit of this percentage is preferably 20 mol% or less, more preferably 15 mol% or less. The lower limit of this percentage is preferably 8 mol% or more, more preferably 10 mol% or more.

[0038] The copolymer (A3) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0039] The proportion of copolymer (A3) relative to the total of copolymer (A1), copolymer (A2), and copolymer (A3) is preferably 5 to 45% by weight, from the viewpoint of the balance between productivity and mechanical properties. By setting the proportion of copolymer (A3) to 5% by weight or more, good productivity can be achieved. Furthermore, by setting this proportion to 45% by weight or less, good mechanical properties can be imparted. The lower limit of this proportion is preferably 10% by weight or more. Furthermore, the upper limit of this proportion is preferably 40% by weight or less, more preferably 30% by weight or less, and even more preferably 25% by weight or less.

[0040] [Poly(3-hydroxybutyrate) (B)] Poly(3-hydroxybutyrate) (B) refers to a homopolymer of 3-hydroxybutyrate, but may contain small amounts of monomer units other than 3-hydroxybutyrate units. Specifically, the content of 3-hydroxybutyrate units in the total constituent monomers of poly(3-hydroxybutyrate) (B) is preferably more than 99 mol% and 100 mol% or less. Use of this poly(3-hydroxybutyrate) (B) can improve the solidification properties of the P3HA-containing thermally processable composition during thermal processing.

[0041] The monomer units other than the 3-hydroxybutyrate units contained in the poly(3-hydroxybutyrate) (B) are not particularly limited as long as they are copolymerizable with the 3-hydroxybutyrate units, but examples thereof include 3-hydroxyalkanoate units other than the 3-hydroxybutyrate units and hydroxyalkanoate units other than the 3-hydroxyalkanoate units (e.g., 4-hydroxyalkanoate units). Specific examples include the units described above for the poly(3-hydroxyalkanoate) copolymer.

[0042] The content of poly(3-hydroxybutyrate) (B) in the raw material composition may be set as appropriate, but is preferably 5% by weight or more and 15% by weight or less, based on 100% by weight of the total of the poly(3-hydroxyalkanoate) copolymer (A) and poly(3-hydroxybutyrate) (B) contained in the raw material composition. A content of 5% by weight or more can increase the solidification rate of the entire P3HA, making it easier to improve the productivity of the thermal processing composition. The lower limit of the content is more preferably 8% by weight or more, and even more preferably 10% by weight or more. Furthermore, a content of 15% by weight or less can easily suppress poor mixing of the resin components. The upper limit is more preferably 13% by weight or less.

[0043] From the viewpoint of achieving both mechanical properties and productivity, the average content ratio of 3-hydroxybutyrate units and other hydroxyalkanoate units among all monomer units constituting the entire P3HA contained in the raw material composition is preferably 3-hydroxybutyrate units / other hydroxyalkanoates = 93 / 7 to 80 / 20 (mol % / mol %), more preferably 92 / 8 to 81 / 18 (mol % / mol %), and even more preferably 90 / 10 to 82 / 16 (mol % / mol %).

[0044] The average content ratio of each monomer unit to all monomer units constituting the entire P3HA 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 constituting the entire P3HA.

[0045] The weight average molecular weight of P3HA is not particularly limited, but from the viewpoint of achieving both mechanical properties and productivity, 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.

[0046] The weight-average molecular weights of copolymer (A1), copolymer (A2), copolymer (A3), and poly(3-hydroxybutyrate) (B) are not particularly limited. However, from the viewpoint of achieving both mechanical properties and productivity, the weight-average molecular weights of copolymer (A1) and poly(3-hydroxybutyrate) (B) are each preferably 200,000 to 1,000,000, more preferably 220,000 to 800,000, and even more preferably 250,000 to 700,000. On the other hand, from the viewpoint of achieving both mechanical properties and productivity, the weight-average molecular weights of copolymer (A2) and copolymer (A3) are each 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.

[0047] The weight-average molecular weight of P3HA, copolymer (A1), copolymer (A2), copolymer (A3), or poly(3-hydroxybutyrate) (B) 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 gel permeation chromatography, a column appropriate for measuring the weight-average molecular weight may be used.

[0048] The method for producing P3HA is not particularly limited, and may be a production method by 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 P3HA synthesis-related genes have been introduced may be used depending on the P3HA to be produced, or culture conditions, including the type of substrate, may be optimized.

[0049] The method for obtaining a blend of two or more P3HAs 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, etc., or by dissolving two or more resins in a solvent, mixing, and drying.

[0050] (other resins) The raw material composition may contain other resins besides P3HA as long as the effects of the invention are not impaired. Examples of such other resins include aliphatic polyester resins such as polybutylene succinate adipate, polybutylene succinate, polycaprolactone, and polylactic acid, and aliphatic aromatic polyester 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.

[0051] The content of the other resins in the raw material composition is not particularly limited, but is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, even more preferably 10 parts by weight or less, and particularly preferably 5 parts by weight or less, relative to 100 parts by weight of the total P3HA contained in the raw material composition. It may also be 1 part by weight or less. The lower limit of the content of the other resins is not particularly limited, and may even be 0 parts by weight.

[0052] (plasticizer) The raw material composition preferably contains a plasticizer in addition to P3HA, which can further improve productivity.

[0053] The plasticizer is not particularly limited, but from the viewpoint of compatibility with P3HA, it is preferable to use an ester compound having an ester bond in the molecule.

[0054] Examples of ester compounds that can be used as plasticizers include modified glycerin compounds, dibasic acid ester compounds, adipate compounds, polyether ester compounds, benzoate ester compounds, citrate ester compounds, isosorbide ester compounds, and polycaprolactone compounds. Among these, modified glycerin ester compounds, dibasic acid ester compounds, adipate ester compounds, polyether ester compounds, and isosorbide ester compounds are preferred. The ester compounds can be used alone or in combination of two or more. When two or more compounds are used in combination, the mixing ratio of the ester compounds can be appropriately adjusted.

[0055] As the modified glycerin compound, a glycerin ester compound is preferred. As the glycerin ester compound, any of glycerin monoesters, diesters, and triesters can be used, but from the viewpoint of compatibility with P3HA, glycerin triesters are preferred. Among glycerin triesters, glycerin diacetomonoesters are particularly preferred. Specific examples of glycerin diacetomonoesters include glycerin diacetomonolaurate, glycerin diacetomonooleate, glycerin diacetomonostearate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate. Examples of the modified glycerin compound include Riken Vitamin's "Rikemal" PL series and "BIOCIZER."

[0056] Specific examples of dibasic acid ester compounds include dibutyl adipate, diisobutyl adipate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, bis(2-ethylhexyl) azelate, dibutyl sebacate, bis(2-ethylhexyl) sebacate, diethyl succinate, and mixed-group dibasic acid ester compounds.

[0057] Examples of the adipate compounds include diethylhexyl adipate, dioctyl adipate, and diisononyl adipate.

[0058] Examples of polyether ester compounds include polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate.

[0059] As the ester compound, a modified glycerin-based compound is preferred from the viewpoints of cost, versatility, and high biomass content. In particular, from the viewpoint of food contact, a glycerin triester is more preferred, a glycerin diacetomonoester is even more preferred, and glycerin diacetomonolaurate is particularly preferred.

[0060] The amount of plasticizer contained in the raw material composition can be appropriately set taking productivity and mechanical strength into consideration, but is preferably 0.1 to 10 parts by weight per 100 parts by weight of P3HA contained in the raw material composition. The lower limit of the amount of plasticizer is preferably 1 part by weight or more, more preferably 2 parts by weight or more, and even more preferably 3 parts by weight or more. The upper limit is preferably 8 parts by weight or less, more preferably 6 parts by weight or less.

[0061] (additives) The raw material composition may contain additives as long as the effects of the invention are not impaired. Examples of additives that can be used depending on the purpose include crystallization nucleating agents, lubricants, plasticizers, antistatic agents, flame retardants, conductive agents, heat insulating agents, crosslinking agents, antioxidants, ultraviolet absorbers, colorants, inorganic fillers, organic fillers, and hydrolysis inhibitors. Biodegradable additives are particularly preferred.

[0062] Examples of crystallization nucleating agents include sugar alcohols such as pentaerythritol, galactitol, and mannitol; orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, boron nitride, etc. Among these, sugar alcohols are preferred, and pentaerythritol is particularly preferred, as they are particularly effective in promoting the crystallization of P3HA.

[0063] The amount of the crystallization nucleating agent used in the raw material composition 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, relative to 100 parts by weight of the total of P3HA contained in the raw material composition. Furthermore, one type of crystallization nucleating agent or two or more types may be used, and the usage ratio can be appropriately adjusted depending on the purpose.

[0064] However, the raw material composition may 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 0.1 parts by weight per 100 parts by weight of P3HA in total. It may even be less than 0.01 parts by weight. In an embodiment in which sugar alcohols are not added substantially, it is possible to avoid the problems of sugar alcohols bleeding out from the thermal processing composition or molded body and the resulting contamination of the manufacturing equipment.

[0065] When sugar alcohols are not substantially blended, it is preferable to blend talc and / or a fatty acid amide as a nucleating agent, and it is particularly preferable to blend both talc and a fatty acid amide. By using these nucleating agents in combination with poly(3-hydroxybutyrate) (B), the productivity of the thermal processing composition or the molded article can be improved even when sugar alcohols are not substantially blended. Specific examples of fatty acid amides are as follows: Fatty acid amides can function as both a crystal nucleating agent and a lubricant.

[0066] Examples of lubricants include behenamide, oleamide, erucamide, stearamide, palmitamide, N-stearylbehenamide, N-stearylerucamide, ethylenebisstearamide, ethylenebisoleamide, ethylenebiserucamide, ethylenebislauricamide, ethylenebiscapricamide, p-phenylenebisstearamide, polycondensates of ethylenediamine, stearic acid, and sebacic acid, etc. Among these, behenamide and erucamide are preferred because of their particularly excellent lubricating effect on P3HA.

[0067] The amount of lubricant used in the raw material composition 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, relative to 100 parts by weight of the total of P3HA contained in the raw material composition. One type of lubricant may be used, or two or more types may be used, and the usage ratio can be appropriately adjusted depending on the purpose.

[0068] [Resin component (I)] The resin component (I) contained in the raw material composition contains a melt-kneaded mixture of a poly(3-hydroxyalkanoate) copolymer (A) and a poly(3-hydroxybutyrate) (B). Hereinafter, the former may be abbreviated as copolymer (A) and the latter as PHB (B). By using a mixture of copolymer (A) and PHB (B) as resin component (I) rather than PHB (B) itself, improper mixing of the resin components in the thermal processing composition can be suppressed. Furthermore, by using a melt-kneaded product as resin component (I) rather than a blend of pellets or powder, improper mixing of the resin components can be further suppressed. Furthermore, the solidification property of the thermal processing composition during thermal processing can be improved.

[0069] The content of PHB (B) in resin component (I) is preferably 5% by weight or more and 15% by weight or less, based on 100% by weight of the total of copolymer (A) and PHB (B) contained in resin component (I). A content of 5% by weight or more can increase the solidification rate of the entire P3HA, making it easier to improve the productivity of resin component (I) or the thermal processing composition. The lower limit of the content is more preferably 8% by weight or more, and even more preferably 10% by weight or more. Furthermore, a content of 15% by weight or less can easily prevent poor mixing of the resin components. The upper limit is more preferably 13% by weight or less.

[0070] Resin component (I) may contain other resins or additives as described above. When resin component (I) contains other resins or additives, the content thereof is based on 100 parts by weight of the total P3HA contained in resin component (I), and conforms to the range of the content of other resins or additives in the raw material composition described above.

[0071] Resin component (I) preferably contains 50% by weight or more of P3HA, more preferably 70% by weight or more, even more preferably 80% by weight or more, and even more preferably 90% by weight or more.

[0072] Resin component (I) has at least a melting point peak (i) with a peak temperature of 165° C. or higher in differential scanning calorimetry. This peak indicates that resin component (I) contains a P3HA resin component with a high melting point.

[0073] Such a high-melting-point P3HA resin component is unlikely to melt completely when the raw material composition is melted, and some of it tends to remain. Therefore, when a raw material composition containing resin component (I) is melted, the raw material composition as a whole melts to a level that makes it melt-processable, but the high-melting-point P3HA resin component does not melt completely and remains. In this way, the unmelted resin component in the molten resin acts as a crystal nucleating agent during cooling and solidification, making it easier for the molten resin to crystallize and solidify. As a result, the productivity of the thermal processing composition can be improved. Furthermore, the solidification property of the thermal processing composition during thermal processing can also be improved.

[0074] The peak temperature of melting point peak (i) may be 165° C. or higher, but from the viewpoint of further improving the productivity of the thermal processing composition and its solidification property during thermal processing, it is preferably 166° C. or higher, more preferably 167° C. or higher, and even more preferably 168° C. or higher. There are no particular limitations on the upper limit of the peak temperature of melting point peak (i), but from the viewpoint of ease of production, it is preferably 180° C. or lower, more preferably 175° C. or lower, and even more preferably 172° C. or lower.

[0075] Resin component (I) preferably exhibits a crystalline fusion enthalpy of 0.6 J / g or more as calculated for melting point peak (i) in differential scanning calorimetry. This means that resin component (I) contains a reasonable amount of a high-melting-point P3HA resin component that can act as a crystal nucleating agent when the raw material composition is cooled and solidified after melting. This improves the productivity of the thermal processing composition and further enhances the solidification properties of the thermal processing composition during thermal processing.

[0076] The crystalline fusion enthalpy calculated for the melting point peak (i) of the resin component (I) is preferably as large as possible, and is preferably 1 J / g or more, more preferably 2 J / g or more, and even more preferably 3 J / g or more. The upper limit is not particularly limited, but from the viewpoint of facilitating melting of the resin component (I) and suppressing poor mixing of the resin components, it is preferably 20 J / g or less, more preferably 10 J / g or less, and even more preferably 8 J / g or less.

[0077] Resin component (I) preferably has, in addition to melting peak (i), a melting peak (ii) having a peak temperature of 140°C or higher but lower than 165°C in differential scanning calorimetry analysis. Melting peak (ii) indicates that resin component (I) contains a P3HA resin component with a melting point lower than that of melting peak (i). This low-melting-point P3HA resin component is relatively easy to melt, making it easy to melt the entire raw material composition to a level that allows it to be melt-processed.

[0078] The peak temperature of the melting point peak (ii) may be 140°C or higher and lower than 165°C, but for ease of production, it is preferably 145°C or higher and lower than 160°C, and more preferably 150°C or higher and lower than 158°C.

[0079] The difference between the peak temperature of melting peak (i) and the peak temperature of melting peak (ii) is not particularly limited, but from the viewpoint of making it easier to leave the P3HA resin component showing melting peak (i) without completely melting while the entire raw material composition is melted to a level that enables melt processing, it is preferably 5° C. or more, more preferably 10° C. or more, and even more preferably 12° C. or more. The upper limit of this temperature difference is not particularly limited, but from the viewpoint of ease of production, it is preferably 60° C. or less, more preferably 40° C. or less, and even more preferably 25° C. or less.

[0080] The differential scanning calorimetry can be carried out by the method described in detail in the Examples section. The crystalline melting enthalpy calculated for the melting point peak (i) can also be calculated as described in detail in the Examples section.

[0081] The resin component (I) exhibiting the specific melting characteristics described above is produced by melt-kneading the copolymer (A) and P3HB (B) and then cooling and solidifying the mixture. By controlling the maximum temperature experienced by the materials and the production rate when melt-kneading the copolymer (A) and P3HB (B), specific melting characteristics can be imparted to the melt-kneaded product.

[0082] To obtain a resin component (I) exhibiting the specific melting characteristics described above, it is more preferable to control the maximum temperature experienced by the material during the production of resin component (I) so that it is equal to or higher than the melting peak temperature and lower than the melting peak end temperature in differential scanning calorimetry (DSC) measured on the material of resin component (I) before heat melting. This allows some of the P3HA resin crystals to remain unmelted during the production of resin component (I), making it easier to form a new melting peak (i) higher than the melting peak of the material of resin component (I) before heat melting.

[0083] In the present application, the melting point peak temperature refers to the top temperature at which the amount of heat absorption is maximum in a DSC curve obtained by differential scanning calorimetry, and the melting point peak end temperature refers to the temperature at which the melting point peak ends on the higher side than the melting point peak temperature and no endothermic heat is observed.

[0084] The maximum temperature of the material described above does not refer to the set temperature in a processing machine such as an extruder, but refers to the maximum temperature that the material actually exhibits during heating and melting, taking into account the temperature rise due to shear heating. The maximum temperature during heating and melting can be measured, for example, for the material discharged from the die of the extruder. The maximum temperature during heating and melting can vary depending on the set temperature in the extruder (the set temperature of the cylinder or die), the screw configuration of the extruder, the rotation speed, etc., and can be controlled by appropriately adjusting these.

[0085] To control the maximum temperature during production of resin component (I) to a temperature equal to or higher than the peak melting temperature and lower than the end temperature of the peak melting temperature of the material of resin component (I) before heat melting, the P3HA contained in resin component (I) preferably has a broad melting peak in differential scanning calorimetry measured on the entire resin, and specifically, the difference between the peak melting temperature and the end temperature of the peak melting temperature is preferably 10° C. or more. P3HA with such a broad melting peak can be produced by using copolymer (A) and PHB (B) in combination.

[0086] In addition, in order to form the melting point peak (i) in the resin component (I) and increase the crystalline melting enthalpy of the melting point peak (i), it is also desirable to control the production rate of the resin component (I). If the production rate of the resin component (I) is too fast, the melting point peak (i) may not be formed or the crystalline melting enthalpy of the melting point peak (i) may not reach a sufficient value.

[0087] A general processing machine can be used to melt-knead the copolymer (A) and P3HB (B) to produce the resin component (I). Such a processing machine is not particularly limited, and known machines can be used, including, for example, a Banbury mixer, a roll mill, a kneader, and a single-screw or multi-screw extruder. The use of an extruder is particularly preferred.

[0088] The copolymer (A) and P3HB (B) are melt-kneaded, and then cooled and solidified by a conventional method to obtain the resin component (I). The shape of the resin component (I) is not particularly limited and may be, for example, pellets or powder.

[0089] [Resin component (II)] The resin component (II) contained in the raw material composition may contain P3HA. The P3HA may contain only copolymer (A), or may contain both copolymer (A) and PHB (B). Furthermore, resin component (II) may have the same composition as resin component (I).

[0090] When resin component (II) contains PHB(B), the content of PHB(B) in resin component (II) is preferably 5% by weight or more and 15% by weight or less, based on 100% by weight of the total of copolymer (A) and PHB(B) contained in resin component (II). A content of 5% by weight or more can increase the solidification rate of the entire P3HA, making it easier to improve the productivity of resin component (II) or the thermal processing composition. The lower limit of the content is more preferably 8% by weight or more, and even more preferably 10% by weight or more. Furthermore, a content of 15% by weight or less can easily prevent insufficient mixing of the resin components. The upper limit is more preferably 13% by weight or less.

[0091] Resin component (II) may contain other resins or additives as described above. When resin component (II) contains other resins or additives, the content thereof is based on 100 parts by weight of the total of P3HA contained in resin component (II), and conforms to the range of the content of other resins or each additive in the raw material composition described above.

[0092] Resin component (II) preferably contains 50% by weight or more of P3HA, more preferably 70% by weight or more, even more preferably 80% by weight or more, and even more preferably 90% by weight or more.

[0093] Resin component (II) differs from resin component (I) in that it does not have a melting point peak (i) at a peak temperature of 165°C or higher in differential scanning calorimetry. Here, "not having a melting point peak (i)" means that the crystalline melting enthalpy measured in the range of 165°C or higher is zero or extremely small. Specific numerical values ​​include the crystalline melting enthalpy being in the range of 0.1 J / g or less. However, the resin component (II) usually has a melting point peak (ii) whose peak temperature is 140°C or higher and lower than 165°C.

[0094] The resin component (II) exhibiting such melting properties may be a blend of pellets or powders of each resin component without melt-kneading them, or may be a homogenized mixture of each resin component by mixing and melt-kneading them. Alternatively, the resin component (II) may be a blend of the remaining resin components with a melt-kneaded mixture obtained by melt-kneading at least a portion of the resin components. The shape of the resin component (II) is not particularly limited, and may be, for example, pellets or powder.

[0095] When the resin component (II) is a melt-kneaded product, the melt-kneaded product can be produced without applying the production conditions described for the resin component (I). For example, the resin component (II) can be produced by melt-kneading at a temperature exceeding the end temperature of the melting point peak measured for the resin component. In other words, the resin component (II) can be produced with high productivity without the need to control the maximum temperature during melting or the production rate. The use of such a resin component (II) makes it possible to improve overall productivity, including the productivity of each resin component. Furthermore, it is preferable that the resin component (II) after melt kneading is cooled to a temperature equal to or lower than the end temperature of the melting point peak ((i)) of the resin component (I) before being used for blending with the resin component (I).

[0096] In this embodiment, by using a resin component (II) that does not have a melting point peak (i) in combination with a resin component (I) that has a melting point peak (i) and adopting the melting conditions described below, a P3HA-containing thermal processing composition that has improved solidification properties during thermal processing compared to when resin component (II) is used alone can be produced with good productivity.In this embodiment, it can also be said that the use of resin component (I) can improve the solidification properties of resin component (II) during thermal processing. Furthermore, according to this embodiment, the productivity of the thermal processable composition can be improved compared to when the resin component (I) is used alone.

[0097] The ratio of resin component (I) to resin component (II) used is not particularly limited and can be set appropriately. The higher the proportion of resin component (I), the better the solidification property of the thermal processing composition during thermal processing. However, as the proportion of resin component (I) increases, the overall productivity, including the productivity of each resin component, tends to decrease. Therefore, the content of resin component (I) per 100 parts by weight of resin component (II) is preferably 0.1 to 50 parts by weight. The lower limit is more preferably 0.5 parts by weight or more, even more preferably 1 part by weight or more, and particularly preferably 2 parts by weight or more. The upper limit 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.

[0098] The raw material composition containing P3HA may contain resin component (I) and resin component (II). It may be a blend of pellets or powders of resin component (I) and resin component (II) without melt-kneading, or may be a homogenized mixture of the resin components by mixing and melt-kneading them. Alternatively, at least a portion of resin component (I) and resin component (II) may be melted, and then the remaining portion may be added. For example, resin component (II) may be melted in an extruder, and then resin component (I) may be added from a side feeder of the extruder. The form of the raw material composition is not particularly limited, and may be, for example, pellets or powder.

[0099] [Melting process of raw material composition] According to this embodiment, the raw material composition described above is melted and then cooled and solidified to produce a thermal processing composition. A general processing machine can be used to heat and melt the raw material composition. Such a processing machine is not particularly limited, and known machines can be used, including, for example, a Banbury mixer, a roll mill, a kneader, and a single-screw or multi-screw extruder. The use of an extruder is particularly preferred.

[0100] The raw material composition is melted under conditions such that the maximum temperature experienced by the raw material composition during melting is equal to or lower than the end temperature of the melting peak (i) of the resin component (I). This allows some crystals of the high-melting-point P3HA resin component derived from the resin component (I) to remain unmelted during melting of the raw material composition. This high-melting-point resin component acts as a crystal nucleating agent during solidification by cooling, thereby improving the productivity of the thermally processed composition. Furthermore, as described below, the thermally processed composition obtained by this melting step has a melting peak (i') at a peak temperature of 165°C or higher, and the crystalline melting enthalpy associated with this peak can be large, resulting in favorable solidification during thermal processing.

[0101] The maximum temperature of the raw material composition during melting does not refer to the set temperature in a processing machine such as an extruder, but refers to the maximum temperature that the material actually exhibits during heat melting, taking into account the temperature rise due to shear heat. The maximum temperature during heat melting can be measured, for example, for the material discharged from the die of the extruder. The maximum temperature during heat melting can vary depending on the set temperature in the extruder (set temperature of the cylinder or die), the screw configuration of the extruder, the rotation speed, etc., and can be controlled by appropriately adjusting these.

[0102] The maximum temperature of the raw material composition during melting is not particularly limited as long as it is equal to or lower than the end temperature of melting point peak (i), but is preferably equal to or lower than a temperature 3°C lower than the end temperature (end temperature -3°C), more preferably equal to or lower than a temperature 5°C lower than the end temperature (end temperature -5°C), and even more preferably equal to or lower than a temperature 8°C lower than the end temperature (end temperature -8°C). As described above, the upper limit of the maximum temperature of the raw material composition is determined in relation to the end temperature of melting point peak (i) of resin component (I), and a specific numerical value is preferably equal to or lower than 175°C, more preferably equal to or lower than 170°C.

[0103] The lower limit of the maximum temperature of the raw material composition during melting is not particularly limited as long as it is equal to or higher than the temperature at which the raw material composition can be melted. However, the higher the maximum temperature, the easier it is to suppress insufficient mixing of the resin components. Specifically, it is preferably 140°C or higher, more preferably 150°C or higher, and even more preferably 160°C or higher. Note that Patent Document 1 specifies that the temperature of the material during extrusion should be controlled to be equal to or higher than the melting point peak temperature of the material, whereas in this embodiment, the maximum temperature of the raw material composition during melting does not need to be controlled to be equal to or higher than the peak temperature of the melting point peak (i).

[0104] The production method according to the present disclosure has good productivity for the thermal processable composition, and the residence time of the raw material composition in the extruder can be kept to 6 minutes or less. Because the residence time in the extruder is short, thermal degradation of the resin can be minimized. From the viewpoint of preventing insufficient mixing of the resin components and improving solidification during thermal processing, the lower limit of the residence time is preferably 30 seconds or more, more preferably 1 minute or more, even more preferably 2 minutes or more, and particularly preferably 3 minutes or more.

[0105] As described above, the raw material composition is heated and melted, and then cooled and solidified by a conventional method to obtain a composition for thermal processing. The shape of the composition for thermal processing is not particularly limited, and may be, for example, pellets or powder.

[0106] In this application, "thermal processing" refers to a process in which a resin composition is heated to melt or soften at least a portion thereof and change its shape. A "composition for thermal processing" refers to a resin composition to be used in such thermal processing.

[0107] The thermal processing composition obtained by the production method according to the present disclosure can have at least a melting point peak (i') with a peak temperature of 165°C or higher in differential scanning calorimetry. This peak indicates that the thermal processing composition contains a high-melting-point P3HA resin component. Such a high-melting-point resin component is unlikely to completely melt when the thermal processing composition is subjected to thermal processing. This unmelted resin component acts as a crystal nucleating agent during cooling and solidification after thermal processing, making it easier for the molten resin to crystallize and solidify, improving solidification properties.

[0108] The peak temperature of the melting point peak (i') may be 165°C or higher, but from the viewpoint of further enhancing solidification properties during thermal processing, it is preferably 166°C or higher, more preferably 167°C or higher, and even more preferably 168°C or higher. The upper limit of the peak temperature of the melting point peak (i') is not particularly limited, but from the viewpoint of ease of production, it is preferably 180°C or lower, more preferably 175°C or lower.

[0109] The thermal processing composition obtained by the manufacturing method according to the present disclosure can exhibit a crystalline melting enthalpy of 0.6 J / g or more calculated for the melting point peak (i') in differential scanning calorimetry. This means that the thermal processing composition contains a reasonable amount of a high-melting-point P3HA resin component that can act as a crystal nucleating agent during cooling and solidification after thermal processing. This further improves solidification properties during thermal processing.

[0110] The crystalline melting enthalpy calculated for the melting point peak (i') of the thermal processing composition is preferably as large as possible, and is preferably 0.8 J / g or more, more preferably 1 J / g or more, and even more preferably 1.2 J / g or more. The upper limit is not particularly limited, but from the viewpoint of facilitating melting or softening of the thermal processing composition, it is preferably 20 J / g or less, more preferably 10 J / g or less, and even more preferably 5 J / g or less.

[0111] The thermally processable composition obtained by the production method according to the present disclosure may usually have a melting point peak (i') having a peak temperature of 165° C. or higher, as well as a melting point peak (ii') having a peak temperature of 140° C. or higher but lower than 165° C. This allows the thermally processable composition to be melted or softened to a level that makes it thermally processable during thermal processing of the thermally processable composition.

[0112] [Thermal processing process] The composition for thermal processing obtained by the production method according to the present disclosure can be thermally processed to produce a molded product. Although not particularly limited, in this thermal processing, the composition for thermal processing can be fed into an extruder equipped with a die at its tip, heated and melted in the extruder, extruded from the die outlet, and then cooled and solidified to produce a molded product.

[0113] In this step, it is preferable to first remove moisture from the thermal processing composition by sufficiently drying it at about 40 to 80° C. Then, if necessary, any other resin or additive as described above is blended, and a known thermal processing method is applied to produce a molded product of any shape.

[0114] Examples of thermal processing methods include extrusion molding, blow molding, injection molding, press molding, vacuum molding, fiber spinning, extrusion foaming, and bead foaming.

[0115] The specific method and conditions for thermal processing are not particularly limited and can follow known information. However, the maximum temperature experienced by the thermal processing composition during thermal processing is preferably 160°C or higher, more preferably 165°C or higher. By heating under such temperature conditions, the thermal processing composition exhibiting the melting point peak (i') can be sufficiently melted or softened, allowing for the production of a molded product with high uniformity and excellent physical properties. The upper limit of the maximum temperature is not particularly limited, but from the viewpoint of avoiding resin decomposition, it is preferably 180°C or lower, more preferably 175°C or lower.

[0116] According to one aspect of this embodiment, the molded article may be a tube, which can be molded by extruding the mixture from an annular die connected to the tip of an extruder and immersing it in water to solidify it.

[0117] A tube is a hollow, elongated cylindrical molded product with a substantially uniform wall thickness and a substantially circular cross-sectional shape. The tube can be used as, but is not limited to, a straw or a pipe.

[0118] The tube used as a straw may be a tube that has not undergone secondary processing, or may be a tube that has undergone secondary processing such as the formation of a stopper portion or a bellows portion.

[0119] When the tube according to the present disclosure is subjected to secondary processing, the secondary processing may be performed at room temperature or under heating. The tube according to the present disclosure can be suitably subjected to secondary processing involving heating. The heating temperature during secondary processing can be appropriately set, and may be, for example, about 100 to 150°C.

[0120] According to one aspect of this embodiment, the molded article may be a film. Examples of methods for molding the film include T-die extrusion molding and inflation molding.

[0121] 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 thermal processing composition containing a poly(3-hydroxyalkanoate)-based resin, comprising: The method includes a step of melting a raw material composition containing a poly(3-hydroxyalkanoate) resin, followed by cooling and solidifying the raw material composition to obtain a composition for thermal processing, the raw material composition comprises a resin component (I) having a melting point peak (i) whose peak temperature is 165°C or higher in differential scanning calorimetry analysis, and a resin component (II) not having the melting point peak (i); The resin component (I) contains a melt-kneaded product of a poly(3-hydroxyalkanoate) copolymer (A) and a poly(3-hydroxybutyrate) (B), The method for producing a composition for thermal processing, wherein the raw material composition is melted under conditions such that the maximum temperature of the raw material composition is equal to or lower than the end temperature of the melting point peak (i). [Item 2] Item 2. The method for producing a composition for thermal processing according to Item 1, wherein the resin component (I) further has a melting point peak (ii) having a peak temperature of 140°C or higher but lower than 165°C in differential scanning calorimetry. [Item 3] 3. The method for producing a composition for thermal processing according to item 1 or 2, wherein the crystalline melting enthalpy calculated for the melting point peak (i) of the resin component (I) is 0.6 J / g or more. [Item 4] 4. The method for producing a composition for thermal processing according to any one of items 1 to 3, wherein the content of the resin component (I) is 0.1 to 50 parts by weight based on 100 parts by weight of the resin component (II). [Item 5] 5. The method for producing a composition for thermal processing according to any one of items 1 to 4, wherein the maximum temperature of the raw material composition during melting is 140°C or higher and 170°C or lower. [Item 6] 6. The method for producing a composition for thermal processing according to any one of items 1 to 5, wherein the residence time of the raw material composition in the extruder is 6 minutes or less. [Item 7] 7. The method for producing a composition for thermal processing according to any one of items 1 to 6, wherein the composition for thermal processing has a melting point peak (i') having a peak temperature of 165°C or higher in differential scanning calorimetry. [Item 8] 8. The method for producing a composition for thermal processing according to Item 7, wherein the crystalline melting enthalpy calculated for the melting point peak (i') of the composition for thermal processing is 0.6 J / g or more. [Item 9] The poly(3-hydroxyalkanoate) copolymer (A) is A copolymer (A1) of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of other hydroxyalkanoate units is 1 to 5 mol %, and 9. A method for producing a composition for thermal processing according to any one of items 1 to 8, comprising a copolymer (A2) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 24 mol% or more. [Item 10] The poly(3-hydroxyalkanoate) copolymer (A) is Item 10. The method for producing a thermal processing composition according to Item 9, further comprising a copolymer (A3) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 6 mol% or more and less than 24 mol%. [Item 11] A method for producing a molded article comprising a poly(3-hydroxyalkanoate) resin, the method comprising the steps of obtaining a composition for thermal processing by the production method according to any one of items 1 to 10, and then thermally processing the composition for thermal processing to produce a molded article. [Example]

[0122] 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.

[0123] The substances used in the examples and comparative examples are shown below. [Poly(3-hydroxyalkanoate) resin] PHB: Poly(3-hydroxybutyrate) (weight average molecular weight: 300,000 g / mol) It was produced according to the method described in Comparative Example 1 of WO 2004 / 041936. P3HB3HH-3: P3HB3HH (average content ratio of 3HB / 3HH = 97.1 / 2.9 (mol% / mol%), weight average molecular weight is 300,000 g / mol) Produced in accordance with the method described in WO 2019 / 142845. P3HB3HH-13: P3HB3HH (Kaneka Biodegradable Polymer PHBH (registered trademark)) (average content ratio 3HB / 3HH = 87.1 / 12.9 (mol% / mol%), weight average molecular weight 330,000 g / mol) P3HB3HH-30: P3HB3HH (average content ratio of 3HB / 3HH = 70.5 / 29.5 (mol% / mol%), weight average molecular weight is 640,000 g / mol) Produced in accordance with the method described in Example 9 of WO 2019 / 142845.

[0124] [Additives] Additive-1: BA, behenamide (Nippon Fine Chemical Co., Ltd.: BNT-22H) Additive-2: EA, erucic acid amide (Neutron-S, manufactured by Nippon Fine Chemical Co., Ltd.)

[0125] [Plasticizer] Plasticizer: Glycerin diacetomonolaurate (Riken Vitamin Co., Ltd.: BIOCIZER)

[0126] The evaluation methods used in the examples and comparative examples are described below. [Measurement of melting peak temperature and crystalline melting enthalpy in differential scanning calorimetry] The melting point peak temperature and crystalline melting enthalpy of the melt-kneaded product of resin component (I), the powder blend as a control product of resin component (I), resin component (II) (pellets), and the thermally processable resin composition were measured by the following procedure. Approximately 2 mg of the sample was weighed and subjected to thermal analysis using a differential scanning calorimeter (TA Instruments, Model DSC25). The sample was heated from -30°C to 180°C at a rate of 10°C per minute to obtain a DSC curve. In the obtained DSC curve, the temperature at which the endotherm reached a maximum was taken as the peak temperature of the melting point peak, and the temperature at which the melting point peak ended and no endotherm was observed above the peak temperature was taken as the end temperature of the melting point peak.

[0127] In addition, in the DSC curve, baselines were drawn at the temperatures before the onset and after the end of the melting peak (if there are two or more melting peaks, the baselines were drawn at the temperatures before the onset of the lowest melting peak and the temperature after the end of the highest melting peak), and this was designated as line a. The area of ​​the melting region enclosed by line a and the DSC curve (if there are two or more melting peaks, line b was drawn perpendicular to the horizontal axis (temperature axis) from the maximum point observed between the highest melting peak (i) and the adjacent melting peak on the lower side, and the area of ​​the region enclosed by the two lines a and b and the DSC curve) was calculated as the crystalline melting enthalpy (J / g) calculated for the melting peak (i) of the sample.

[0128] [Film haze evaluation] 10 mg of the heat-processable resin composition was immersed in 4 mL of chloroform and kept at 60°C for 1 hour. It has been confirmed that crystals with a melting point peak of 165°C or higher are poorly soluble in chloroform and do not completely dissolve when kept at 60°C for 1 hour. The resulting chloroform solution was poured into a 100 mm diameter glass plate and dried at room temperature for 30 minutes to obtain a cast film. The total haze of the cast film was measured using a haze meter (HZ-V3, manufactured by Suga Test Instruments Co., Ltd.) under a D65 light source in accordance with JIS K 7136. When the total haze is less than 70%, it can be said that there is little particulate foreign matter in the film and that the resin components in the heat-processable resin composition are sufficiently melted and kneaded.

[0129] The preparation of resin component (I), its control product, and resin component (II) used in the examples and comparative examples will be described below. [Preparation of resin component (I)] (Melted mixture) Resin composition (II) (pellets) prepared by the method described below was kneaded in a 26 mm diameter twin-screw extruder, and a strand-like resin material was extruded at a rate of 5 kg / hour. The extruder's cylinder and die temperatures were set to 151°C, and the screw was rotated at 30 revolutions per minute. The extruded strand-like resin material was passed through a 40°C water bath and cut with a pelletizer to obtain a molten kneaded product, which was resin component (I). The melting point peak temperature and crystalline fusion enthalpy of the resulting molten kneaded product were measured by differential scanning calorimetry, and the results are shown in Table 1.

[0130] (powder blend) A powder blend was prepared by blending 0.242 kg of PHB, 1.142 kg of P3HB3HH-3, 0.456 kg of P3HB3HH-30, and 0.16 kg of P3HB3HH-13 with 20 g of additive-1, 10 g of additive-2, and 86 g of plasticizer. The peak melting point and enthalpy of crystalline fusion of this powder blend were measured by differential scanning calorimetry, and the results are shown in Table 1.

[0131] [Preparation of Resin Composition (II) (Pellets)] To obtain the resin composition shown in Table 1, 0.242 kg of PHB, 1.142 kg of P3HB3HH-3, 0.456 kg of P3HB3HH-30, 0.16 kg of P3HB3HH-13, 20 g of Additive-1, 10 g of Additive-2, and 86 g of plasticizer were blended. The resulting blend was kneaded using a 26 mm diameter co-rotating twin-screw extruder, and strand-like resin material was extruded at a rate of 20 kg / hour. The extruder's cylinder and die temperatures were set to 150°C, and the screw was rotated at 250 revolutions per minute. The extruded strand-like resin material was passed through a 40°C water bath and cut using a pelletizer to obtain resin composition (II) (pellets). The melting point peak temperature and crystalline melting enthalpy of the resulting resin composition (II) were measured by differential scanning calorimetry, and the results are shown in Table 1.

[0132] [Table 1]

[0133] Example 1 A small kneader (DSM Xplore 5 Model 2005) was used, with the barrel temperature set to 160°C and the screw rotating at 100 rpm. According to the formulation shown in Table 2, 5.0 g of the melt-kneaded product as resin component (I) and resin component <II> (pellets) were prepared and blended. The blend was added to the small kneader over 1 minute, and 0.1 g of the melt-kneaded resin composition was obtained 1 minute after the end of raw material addition. The maximum temperature of the resin composition during melt-kneading was 160°C, as shown in Table 2. The discharged resin composition was immediately immersed in 60°C warm water for 30 seconds and then collected. The melting point peak temperature and crystalline fusion enthalpy of the obtained resin composition for heat processing, as well as the haze of the film, were measured by differential scanning calorimetry analysis. The results are shown in Table 2.

[0134] Examples 2 to 9 Resin compositions for heat processing were prepared in the same manner as in Example 1, except that the blending amounts of resin component (I) and resin component (II) or the melt molding conditions were changed according to the description in Table 2. The melting point peak temperature and crystalline melting enthalpy of the obtained resin compositions for heat processing, as well as the haze of the film, were measured in differential scanning calorimetry, and the results are shown in Table 2.

[0135] (Comparative Example 1) A heat-processable resin composition was prepared in the same manner as in Example 1, except that the powder blend was used as the resin component (I) instead of the molten kneaded product. The melting point peak temperature and crystalline fusion enthalpy of the obtained heat-processable resin composition were measured by differential scanning calorimetry, and the haze of the film was measured. The results are shown in Table 2.

[0136] (Comparative Examples 2 to 6, 10 to 12) A resin composition for heat processing was prepared in the same manner as in Comparative Example 1, except that the blending amounts of the powder blend and resin component (II) or the melt molding conditions were changed according to the description in Table 2. The melting point peak temperature and crystalline melting enthalpy of the obtained resin composition for heat processing, as well as the haze of the film, were measured by differential scanning calorimetry analysis, and the results are shown in Table 2.

[0137] (Comparative Examples 7 to 9) A resin composition for heat processing was prepared in the same manner as in Example 1, except that the melt molding conditions were changed according to the description in Table 2. The melting point peak temperature and crystalline melting enthalpy of the obtained resin composition for heat processing, as well as the haze of the film, were measured by differential scanning calorimetry analysis, and the results are shown in Table 2.

[0138] (Comparative Example 13) A heat-processable resin composition was prepared in the same manner as in Example 1, except that resin component (I) was not used. The melting point peak temperature and crystalline melting enthalpy of the obtained heat-processable resin composition were measured by differential scanning calorimetry, and the haze of the film was measured. The results are shown in Table 2.

[0139] (Comparative Examples 14 to 16) A resin composition for heat processing was prepared in the same manner as in Comparative Example 13, except that the melt molding conditions were changed according to the description in Table 2. The melting point peak temperature and crystalline melting enthalpy of the obtained resin composition for heat processing, as well as the haze of the film, were measured by differential scanning calorimetry analysis, and the results are shown in Table 2.

[0140] [Table 2]

[0141] Table 1 reveals the following. In Examples 1 to 9, the residence time in the extruder was short, i.e., the productivity was high, and thermally processable compositions containing poly(3-hydroxyalkanoate) resins were successfully produced. The produced thermally processable compositions had a melting point peak (i') with a peak temperature of 165°C or higher, and the crystalline melting enthalpy calculated for the melting point peak was relatively large, indicating that they had good solidification properties during thermal processing. Furthermore, the haze value was less than 70%, indicating that poor mixing of the resin components was also suppressed.

[0142] On the other hand, in Comparative Examples 1 to 6, in which a powder blend was used instead of the molten kneaded resin component (I) to obtain a composition for thermal processing, the haze value was 70% or more, indicating poor mixing of the resin components. Furthermore, in Comparative Examples 1 and 4 to 6, the values ​​of crystalline fusion enthalpy calculated for the melting point peak (i') were small, indicating poor solidification during thermal processing.

[0143] In Comparative Examples 7 to 12, in which compositions for thermal processing were obtained by melt processing the molten kneaded product or powder blend, which is the resin component (I), at a temperature exceeding the end temperature of the melting point peak (i), no melting point peak (i') was observed, indicating that the solidification properties during thermal processing were poor.

[0144] Furthermore, in Comparative Examples 13 to 16, in which the thermal processing composition was produced from only the resin component (II) without using the resin component (I) as the raw material composition, the value of the crystalline melting enthalpy calculated for the melting point peak (i') of the obtained thermal processing composition was small (Comparative Example 13), or the melting point peak (i') was not observed (Comparative Examples 14 to 16), indicating poor solidification properties during thermal processing.

Claims

1. A method for producing a thermal processing composition containing a poly(3-hydroxyalkanoate)-based resin, comprising: The method includes a step of melting a raw material composition containing a poly(3-hydroxyalkanoate) resin, followed by cooling and solidifying the raw material composition to obtain a composition for thermal processing, The raw material composition includes a resin component (I) having a melting point peak (i) whose peak temperature is 165°C or higher in differential scanning calorimetry analysis, and a resin component (II) not having the melting point peak (i), The resin component (I) contains a melt-kneaded mixture of a poly(3-hydroxyalkanoate) copolymer (A) and a poly(3-hydroxybutyrate) (B), The method for producing a composition for thermal processing, wherein the raw material composition is melted under conditions in which the maximum temperature of the raw material composition is equal to or lower than the end temperature of the melting point peak (i).

2. The method for producing a composition for thermal processing according to claim 1, wherein the resin component (I) further has a melting point peak (ii) having a peak temperature of 140°C or higher but lower than 165°C in differential scanning calorimetry.

3. 3. The method for producing a composition for thermal processing according to claim 1, wherein the crystalline melting enthalpy calculated for the melting point peak (i) of the resin component (I) is 0.6 J / g or more.

4. 3. The method for producing a composition for thermal processing according to claim 1, wherein the content of said resin component (I) is 0.1 to 50 parts by weight based on 100 parts by weight of said resin component (II).

5. 3. The method for producing a composition for thermal processing according to claim 1, wherein the maximum temperature of the raw material composition during melting is 140°C or higher and 170°C or lower.

6. 3. The method for producing a composition for thermal processing according to claim 1, wherein the residence time of the raw material composition in the extruder is 6 minutes or less.

7. The method for producing a composition for thermal processing according to claim 1 or 2, wherein the composition for thermal processing has a melting point peak (i') having a peak temperature of 165°C or higher in differential scanning calorimetry.

8. 8. The method for producing a composition for thermal processing according to claim 7, wherein the crystalline melting enthalpy calculated for the melting point peak (i') of the composition for thermal processing is 0.6 J / g or more.

9. The poly(3-hydroxyalkanoate) copolymer (A) is A copolymer (A1) of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of the other hydroxyalkanoate units is 1 to 5 mol %, and 3. The method for producing a composition for thermal processing according to claim 1 or 2, comprising a copolymer (A2) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 24 mol% or more.

10. The poly(3-hydroxyalkanoate) copolymer (A) is The method for producing a composition for thermal processing according to claim 9, further comprising a copolymer (A3) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 6 mol% or more and less than 24 mol%.

11. A method for producing a molded article containing a poly(3-hydroxyalkanoate) resin, comprising the steps of obtaining a composition for thermal processing by the production method according to claim 1 or 2, and then thermally processing the composition for thermal processing to produce a molded article.

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