Resin composition and molded body

Abstract

This resin composition contains a poly(3-hydroxyalkanoate) resin (A) and an inorganic filler (B). The resin (A) includes a copolymer (A3) of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit in which the content ratio of the 3-hydroxybutyrate unit is 76 mol% or less, and a copolymer (A4) of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit in which the weight average molecular weight is 700,000 or more and the content ratio of the 3-hydroxybutyrate unit is more than 76 mol% and 95 mol% or less. Of the content (X) of the resin (A) excluding the copolymer (A4), the content of the copolymer (A3) is 5-25 wt%, and the content of the copolymer (A4) is 5-30 parts by weight and the content of the inorganic filler (B) is 5-40 parts by weight relative to 100 parts by weight of the content (X).

Description

Resin composition and molded article

[0001] The present invention relates to a resin composition containing a poly(3-hydroxyalkanoate) resin and a molded article thereof.

[0002] Poly(3-hydroxyalkanoate) resins are materials that can be biodegraded even in seawater, and are therefore attracting attention as a material that can solve the problem of marine pollution caused by plastics.

[0003] Patent Document 1 describes that by blending a specific amount of a layered clay mineral with a poly(3-hydroxyalkanoate) resin containing two copolymers having a specific monomer ratio, an injection-molded article having a practical balance between elastic modulus and toughness can be produced with good productivity.

[0004] International Publication No. 2022 / 065182

[0005] According to the technique described in Patent Document 1, a practical balance between elastic modulus and toughness can be achieved by blending a layered clay mineral with a poly(3-hydroxyalkanoate) resin. However, it was found that the composition disclosed in Patent Document 1 is prone to deformation and cracking under high temperature and pressure, and has insufficient crack resistance.

[0006] In view of the above-described current situation, the present invention aims to provide a resin composition containing a poly(3-hydroxyalkanoate)-based resin, which is inhibited from deforming and cracking under high temperature and pressure conditions and has improved crack resistance, and a molded article made from the resin composition.

[0007] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that, in addition to blending an inorganic filler in a specific ratio with a poly(3-hydroxyalkanoate) resin, a resin composition can be obtained in which deformation and cracking under high temperature and pressure conditions are suppressed and cracking resistance is improved by using, in combination, a specific ratio of multiple poly(3-hydroxybutyrate) copolymers having a specific monomer composition as the poly(3-hydroxyalkanoate) resin, and setting the molecular weight of one of the copolymers to a high level, thereby achieving the present invention.

[0008] That is, the present invention provides a resin composition containing a poly(3-hydroxyalkanoate) resin (A) and an inorganic filler (B), wherein the poly(3-hydroxyalkanoate) resin (A) comprises: a copolymer (A3) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the copolymer having a 3-hydroxybutyrate unit content of 76 mol% or less; and a copolymer (A4) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the copolymer having a weight average molecular weight of 700,000 or more and a 3-hydroxybutyrate unit content of more than 76 mol% and 95 mol% or less; the content of the copolymer (A3) in the content (X) of the poly(3-hydroxyalkanoate) resin (A) excluding the copolymer (A4) is 5% by weight or more and 25% by weight or less; and the content of the copolymer (A4) per 100 parts by weight of the content (X) is 5 parts by weight or more and 30 parts by weight or less; The present invention relates to a resin composition, wherein the content of the inorganic filler (B) is 5 parts by weight or more and 40 parts by weight or less per 100 parts by weight of the content (X). The present invention also relates to a molded article comprising the resin composition.

[0009] According to the present invention, it is possible to provide a resin composition containing a poly(3-hydroxyalkanoate)-based resin, which is inhibited from deforming and cracking under high temperature and pressure conditions and has improved crack resistance, and a molded article made from the resin composition.

[0010] A graph showing the test force on the vertical axis and the displacement on the horizontal axis, obtained from a bending test to measure fracture energy

[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 is a resin composition containing a poly(3-hydroxyalkanoate)-based resin (A). The resin composition can be suitably used to produce a molded article.

[0013] (Poly(3-hydroxyalkanoate)-based resin (A)) The poly(3-hydroxyalkanoate)-based resin is a polymer having a 3-hydroxyalkanoate unit, and specifically, is preferably a polymer containing a unit represented by the following general formula (1): [—CHR—CH ２ -CO-O-] (1) 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 an integer of 1 to 10, and more preferably an integer of 1 to 8.

[0014] 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.

[0015] 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 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).

[0016] 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 of the 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.

[0017] 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 productivity and mechanical properties of 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.

[0018] In this embodiment, the poly(3-hydroxyalkanoate) resin (A) contains at least the following two types of copolymers: a copolymer (A3) of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of 3-hydroxybutyrate units is 76 mol% or less, and a copolymer (A4) of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the weight-average molecular weight is 700,000 or more and the content of 3-hydroxybutyrate units is more than 76 mol% and 95 mol% or less.

[0019] In copolymers of 3-hydroxybutyrate units and other hydroxyalkanoate units, the crystallinity generally tends to decrease as the content of 3-hydroxybutyrate units decreases. While copolymer (A3) has a low content of 3-hydroxybutyrate units and low crystallinity, copolymer (A4) has higher crystallinity than copolymer (A3). Highly crystalline poly(3-hydroxyalkanoate) resins have good strength but low toughness, while low-crystalline poly(3-hydroxyalkanoate) resins have good toughness but insufficient strength. Thus, by using a low-crystalline copolymer in combination with a copolymer with relatively high crystallinity, a balance between strength and toughness can be achieved. Furthermore, by using a high-molecular-weight copolymer as the relatively highly crystalline copolymer, deformation and cracking under high temperature and pressure can be suppressed, improving crack resistance.

[0020] In copolymer (A3), the content of 3-hydroxybutyrate units in the total of 3-hydroxybutyrate units and other hydroxyalkanoate units is 76 mol% or less. From the viewpoints of suppressing deformation and cracking and improving crack resistance, this content is preferably 74 mol% or less, and more preferably 72 mol% or less. Furthermore, from the viewpoint of productivity of copolymer (A3), the lower limit of this content is preferably 1 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, and particularly preferably 70 mol% or more.

[0021] As the copolymer (A3), the copolymers described above can be used, but 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.

[0022] The weight-average molecular weight of copolymer (A3) is not particularly limited and may be set appropriately taking into consideration the weight-average molecular weight of the entire poly(3-hydroxyalkanoate) resin (A), but from the viewpoint of achieving both mechanical properties and productivity of the molded article, it is preferably 200,000 to 2,000,000, more preferably 250,000 to 1,500,000, and particularly preferably 300,000 to 1,000,000. The weight-average molecular weight of copolymer (A3) is preferably less than 700,000, because this makes it easier to realize the effects of using the high-molecular-weight copolymer (A4), which will be described later.

[0023] In this embodiment, the content of copolymer (A3) in the content (X) of poly(3-hydroxyalkanoate) resin (A) excluding copolymer (A4) is set to a range of 5% by weight or more and 25% by weight or less. By setting the content of copolymer (A3) to 5% by weight or more, deformation and cracking under high temperature and high pressure can be suppressed, and crack resistance can be improved. Furthermore, by setting the content to 25% by weight or less, the productivity of the resin composition can be improved. The lower limit of the content is preferably 10% by weight or more. The upper limit of the content is preferably 20% by weight or less, more preferably 17% by weight or less, and even more preferably 15% by weight or less.

[0024] On the other hand, the weight average molecular weight of copolymer (A4) is 700,000 or more. By using such a copolymer with a relatively high molecular weight in combination with copolymer (A3) and the inorganic filler (B) described below, deformation and cracking under high temperature and pressure can be suppressed, and crack resistance can be improved. The molecular weight is preferably 750,000 or more, more preferably 800,000 or more, even more preferably 900,000 or more, and particularly preferably 1,000,000 or more. The upper limit is not particularly limited, but from the viewpoint of productivity, it is preferably 2,500,000 or less, more preferably 2,000,000 or less, and even more preferably 1,500,000 or less.

[0025] In the copolymer (A4), the content of 3-hydroxybutyrate units in the total of 3-hydroxybutyrate units and other hydroxyalkanoate units is more than 76 mol% and not more than 95 mol%, preferably 80 to 95 mol%, more preferably 82 to 94 mol%, even more preferably 85 to 93 mol%, and particularly preferably 87 to 92 mol%.

[0026] As the copolymer (A4), the copolymers described above can be used, but poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is preferred, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is particularly preferred.

[0027] In this embodiment, the content of copolymer (A4) relative to 100 parts by weight of the content (X) of poly(3-hydroxyalkanoate)-based resin (A) excluding copolymer (A4) is set to a range of 5 parts by weight or more and 30 parts by weight or less. By setting the content of copolymer (A4) to 5 parts by weight or more, deformation and cracking under high temperature and pressure can be suppressed, and crack resistance can be improved. Furthermore, by setting the content to 30 parts by weight or less, fluidity during melt processing can be ensured. The upper limit of the content is preferably 25 parts by weight or less, more preferably 20 parts by weight or less, even more preferably 15 parts by weight or less, even more preferably 12 parts by weight or less, and particularly preferably 10 parts by weight or less.

[0028] The poly(3-hydroxyalkanoate) resin (A) may be composed only of the copolymers (A3) and (A4). However, from the viewpoints of achieving a balance between strength and toughness, suppressing deformation and cracking under high temperature and pressure, improving crack resistance, and further improving productivity, it is preferable that the poly(3-hydroxyalkanoate) resin (A) further contains a poly(3-hydroxyalkanoate) resin different from (A3) and (A4).

[0029] Specifically, the poly(3-hydroxyalkanoate) resin (A) preferably further contains one or both of the following two types of copolymers: (A1) a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, having a weight-average molecular weight of 100,000 or more but less than 700,000 and containing more than 76 mol% and not more than 95 mol% of 3-hydroxybutyrate units; and (A2) a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, having a content of more than 95 mol% and not more than 99 mol% of 3-hydroxybutyrate units.

[0030] Copolymer (A1) exhibits crystallinity comparable to that of copolymer (A4), whereas copolymer (A2) has a high content of 3-hydroxybutyrate units and is a resin exhibiting higher crystallinity than copolymers (A1) and (A4).

[0031] By using these copolymers (A1) and / or (A2) in combination with the copolymers (A3) and (A4), a resin composition can be produced with good productivity, which has improved elongation, a good balance between strength and toughness, suppresses deformation and cracking under high temperature and pressure, and has improved crack resistance.

[0032] The weight-average molecular weight of the copolymer (A1) is 100,000 or more but less than 700,000. By using a copolymer with such a relatively low molecular weight, fluidity during melt processing can be ensured. The molecular weight is more preferably 600,000 or less, and even more preferably 500,000 or less. The lower limit is not particularly limited, but from the viewpoint of the strength of the molded product, it is preferably 200,000 or more, and more preferably 300,000 or more.

[0033] In the copolymer (A1), the content of 3-hydroxybutyrate units in the total of 3-hydroxybutyrate units and other hydroxyalkanoate units is more than 76 mol % and not more than 95 mol %, preferably 80 to 95 mol %, more preferably 85 to 95 mol %, even more preferably 90 to 95 mol %, and particularly preferably 93 to 95 mol %.

[0034] As the copolymer (A1), the copolymers described above can be used, but poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is preferred, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is particularly preferred.

[0035] When copolymer (A1) is contained, the content of copolymer (A1) in the content (X) of poly(3-hydroxyalkanoate) resin (A) excluding copolymer (A4) is preferably in the range of 50% by weight or more and 85% by weight or less. By making the content of copolymer (A1) 50% by weight or more, it is possible to improve fluidity during melt processing. Furthermore, by making the content 85% by weight or less, it is possible to suppress deformation and cracking under high temperature and pressure, and improve crack resistance. The lower limit of the content is preferably 60% by weight or more, more preferably 65% ​​by weight or more, and even more preferably 70% by weight or more. Furthermore, the upper limit of the content is preferably 80% by weight or less.

[0036] In the copolymer (A2), the content of 3-hydroxybutyrate units in the total of 3-hydroxybutyrate units and other hydroxyalkanoate units is more than 95 mol% and not more than 99 mol%. From the viewpoints of the balance between strength and toughness and productivity, the upper limit of this percentage is preferably not more than 98 mol%. The lower limit may be not less than 96 mol%.

[0037] As the copolymer (A2), the copolymers described above can be used, but 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.

[0038] The weight-average molecular weight of copolymer (A2) is not particularly limited and may be set appropriately taking into consideration the weight-average molecular weight of the entire poly(3-hydroxyalkanoate) resin (A), but from the viewpoint of achieving both mechanical properties and productivity of the molded article, it is preferably 200,000 to 2,000,000, more preferably 250,000 to 1,500,000, and particularly preferably 300,000 to 1,000,000. The weight-average molecular weight of copolymer (A2) is preferably less than 700,000, because this makes it easier to realize the effects of using high-molecular-weight copolymer (A4).

[0039] When copolymer (A2) is contained, the content of copolymer (A2) in the content (X) of poly(3-hydroxyalkanoate) resin (A) excluding copolymer (A4) is preferably in the range of 5% by weight or more and 25% by weight or less. By setting the content of polymer (A2) to 5% by weight or more, productivity can be improved. Furthermore, by setting the content to 25% by weight or less, deformation and cracking under high temperature and high pressure can be suppressed, and crack resistance can be improved. The lower limit of the content is preferably 10% by weight or more. The upper limit of the content is preferably 20% by weight or less, more preferably 17% by weight or less, and even more preferably 15% by weight or less.

[0040] When copolymer (A2) is contained, the proportion of copolymer (A2) and copolymer (A3) used is not particularly limited, but from the viewpoint of the balance between strength and toughness and productivity, in the total amount of copolymer (A2) and copolymer (A3), the proportion of copolymer (A2) is preferably 35% by weight or more and the proportion of copolymer (A3) is 65% by weight or less, more preferably the proportion of copolymer (A2) is 40% by weight or more and the proportion of copolymer (A3) is 60% by weight or less. Also, the proportion of copolymer (A2) is preferably 75% by weight or less and the proportion of copolymer (A3) is 25% by weight or more, more preferably the proportion of copolymer (A2) is 65% by weight or less and the proportion of copolymer (A3) is 35% by weight or more.

[0041] From the viewpoint of achieving both mechanical properties and productivity of a molded article, the average content ratio of 3-hydroxybutyrate units and other hydroxyalkanoate units in all monomer units constituting the poly(3-hydroxyalkanoate) resin (A) is preferably 3-hydroxybutyrate units / other hydroxyalkanoate units=98 / 2 to 65 / 35 (mol % / mol %), more preferably 96 / 4 to 75 / 25 (mol % / mol %), even more preferably 95 / 5 to 80 / 20 (mol % / mol %), and particularly preferably 96 / 6 to 85 / 15 (mol % / mol %).

[0042] The average content ratio of each monomer unit in all monomer units constituting the poly(3-hydroxyalkanoate) resin (A) or each copolymer 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 of each monomer unit in the poly(3-hydroxyalkanoate) resin (A) means the molar proportion of each monomer unit in all monomer units in the entire poly(3-hydroxyalkanoate) resin (A), and refers to the molar proportion of each monomer unit contained in the entire mixture of multiple poly(3-hydroxyalkanoate) resins constituting the poly(3-hydroxyalkanoate) resin (A).

[0043] The weight average molecular weight of the entire poly(3-hydroxyalkanoate) resin (A) is not particularly limited, but from the viewpoint of achieving both mechanical properties and productivity of the molded article, it is preferably from 50,000 to 3,000,000, more preferably from 200,000 to 2,000,000, even more preferably from 250,000 to 1,500,000, and particularly preferably from 300,000 to 800,000.

[0044] The weight-average molecular weight of the poly(3-hydroxyalkanoate) resin (A) or each copolymer can be measured in terms of polystyrene using gel permeation chromatography (HPLC GPC system manufactured by Shimadzu Corporation) using a chloroform solution. As a column for the gel permeation chromatography, a column appropriate for measuring the weight-average molecular weight may be used.

[0045] The poly(3-hydroxyalkanoate) resin (A) or each copolymer is preferably not crosslinked using a crosslinking agent such as an organic peroxide, that is, it is preferable that it does not have a crosslinked structure.

[0046] 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, with regard to P3HB3HH, in order to increase the productivity of P3HB3HH, Alcaligenes eutrophus AC32 strain (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 more preferred, and microbial cells obtained by culturing these microorganisms under appropriate conditions and allowing P3HB3HH to accumulate within the cells are used. In addition to the above, 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.

[0047] (Inorganic Filler (B)) The resin composition according to this embodiment further contains an inorganic filler (B). By using the inorganic filler (B) in combination with the low-crystalline copolymer (A3) and the high-molecular-weight copolymer (A4), deformation and cracking under high temperature and pressure can be suppressed, and crack resistance can be improved.

[0048] The inorganic filler (B) is not particularly limited, but examples thereof include layered clay minerals such as smectite, mica, talc, pyroferrite, vermiculite, chlorite, kaolinite, and serpentine, as well as silica, titanium oxide, hematite, and calcium carbonate. Only one type of inorganic filler may be used, or two or more types may be used in combination. From the viewpoints of suppressing deformation and cracking under high temperature and pressure and improving crack resistance, mica, talc, kaolinite, silica, titanium oxide, and calcium carbonate are preferred, and talc is particularly preferred.

[0049] Examples of the mica include wet-ground mica and dry-ground mica, and specific examples include mica manufactured by Yamaguchi Mica Co., Ltd. and Keiwa Rozai Co., Ltd.

[0050] Examples of the talc include general-purpose talc and surface-treated talc. Specific examples include "Microace" (registered trademark) from Nippon Talc Co., Ltd., "Talc Powder" (registered trademark) from Hayashi Kasei Co., Ltd., and talc manufactured by Takehara Chemical Industry Co., Ltd. and Maruo Calcium Co., Ltd.

[0051] Examples of the kaolinite include dry kaolin, calcined kaolin, and wet kaolin. Specific examples include "TRANSLINK" (registered trademark), "ASP" (registered trademark), "SANTINTONE" (registered trademark), and "ULTREX" (registered trademark) manufactured by Hayashi Kasei Co., Ltd., and kaolinite manufactured by Keiwa Rozai Co., Ltd.

[0052] The content of the inorganic filler (B) is set in the range of 5 parts by weight or more and 40 parts by weight or less per 100 parts by weight of the content (X) of the poly(3-hydroxyalkanoate)-based resin (A) excluding the copolymer (A4). When the content of the inorganic filler is 5 parts by weight or more, deformation and cracking under high temperature and pressure can be suppressed, and crack resistance can be improved. Furthermore, when the content is 40 parts by weight or less, the resin composition tends to have an appropriate melt viscosity and good moldability. The lower limit of the content is preferably 7 parts by weight or more, more preferably 10 parts by weight or more. Furthermore, the upper limit of the content is preferably 35 parts by weight or less, more preferably 30 parts by weight or less, even more preferably 25 parts by weight or less, and particularly preferably 20 parts by weight or less.

[0053] (Other Resins) The resin composition according to this embodiment may contain other polyester resins besides the poly(3-hydroxyalkanoate) resin (A) as long as the effects of the invention are not impaired. Examples of such other polyester resins include aliphatic aromatic polyester resins such as polybutylene adipate terephthalate resins, polybutylene sebacate terephthalate resins, and polybutylene succinate terephthalate resins, as well as aliphatic polyester resins such as polybutylene succinate adipate, polybutylene succinate, polycaprolactone, and polylactic acid. Only one type of other polyester resin may be contained, or two or more types may be contained.

[0054] The content of the other polyester resin 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 poly(3-hydroxyalkanoate) resin (A). It may even be 1 part by weight or less. The lower limit of the content of the other polyester resin is not particularly limited, and may even be 0 parts by weight.

[0055] The resin composition according to the present embodiment may contain a resin other than a polyester-based resin, but preferably contains a polyester-based resin as the main resin component. The proportion of the polyester-based resin in the total resin components contained in the resin composition according to the present embodiment is preferably 50 to 100 wt %, more preferably 70 to 100 wt %, even more preferably 80 to 100 wt %, and still more preferably 90 to 100 wt %.

[0056] (Additives) The resin composition according to this embodiment 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, UV absorbers, colorants, organic fillers, and hydrolysis inhibitors. Biodegradable additives are particularly preferred.

[0057] Examples of crystallization nucleating agents include pentaerythritol, orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, and boron nitride. Among these, pentaerythritol is preferred because it is particularly effective in promoting the crystallization of the polyester resin component. The amount of crystallization 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 total amount of the polyester resin component. Furthermore, one type of crystallization nucleating agent may be used, or two or more types may be used, and the usage ratio can be appropriately adjusted depending on the purpose.

[0058] 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 or erucamide are preferred because of their particularly excellent lubricating effect on polyester-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 total amount of polyester-based resin components. Furthermore, 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.

[0059] 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 polyester 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 total amount of polyester-based resin components. One type of plasticizer may be used, or two or more types may be used, and the usage ratio can be appropriately adjusted depending on the purpose. However, the content of the plasticizer may be 0 parts by weight or more but less than 1 part by weight, per 100 parts by weight of the total amount of polyester-based resin components. The upper limit may be less than 0.5 parts by weight, or less than 0.1 parts by weight.

[0060] The resin composition according to the present embodiment preferably exhibits good fluidity during melt processing. From this viewpoint, the resin composition preferably has a melt flow rate measured at 165°C of 3 to 12 g / 10 min, more preferably 5 to 10 g / 10 min. The melt flow rate can be measured by the method described in the Examples section.

[0061] The resin composition according to this embodiment has high strength, and therefore can be suitably used to form molded articles with good usability. The fracture energy based on ISO 178-A can be used as an index of good usability. Specifically, the resin composition according to this embodiment preferably exhibits a fracture energy of 0.76 J or more. The fracture energy of acrylonitrile / butadiene / styrene resin (ABS), a general-purpose resin known to have high strength, is 0.76 J. The fracture energy value preferably exhibits 0.8 J or more. The upper limit of the fracture energy is not particularly limited, but may be, for example, 10 J or less, or 5 J or less. The fracture energy can be measured by the method described in the Examples section.

[0062] (Method for producing resin composition) The resin composition according to this embodiment can be produced by melt-kneading each component. After melt-kneading, pelletization may be performed, or a molded product other than pellets may be produced directly without pelletization. The method will be described in detail below.

[0063] First, a polyester resin component and any additives are added and melt-kneaded using an extruder, kneader, Banbury mixer, roll, or the like to prepare a resin composition. The resin composition may be extruded into a strand shape and then cut to obtain pellets having a particle shape such as a cylindrical, elliptical cylindrical, spherical, cubic, or rectangular parallelepiped shape. The prepared pellets are desirably thoroughly dried at 40 to 80°C to remove moisture before being subjected to the next molding step.

[0064] 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 at the die outlet of the melt-kneaded product is preferably 135 to 200° C., more preferably 140 to 195° C., even more preferably 145 to 190° C., and particularly preferably 150 to 185° C. If the resin temperature of the melt-kneaded product is 135° C. or higher, the polyester-based resin component can be uniformly melted, and if it is 200° C. or lower, thermal decomposition of the polyester-based resin component can be avoided.

[0065] The resin composition according to the present embodiment can be used to produce a molded article through a molding process after melt-kneading. The molding method is not particularly limited, but examples thereof include injection molding, extrusion molding, blow molding, and calendar molding. In particular, injection molding is preferably used.

[0066] Specific examples of molded articles, particularly injection molded articles, that can be formed from the resin composition according to this embodiment include capsules for extracting beverages such as coffee capsules, three-dimensional toys, cutlery, cups, and the like.

[0067] The beverage extraction capsule is a type of container for storing beverage substances such as coffee or tea leaves, and is a container in which the beverage substance is filled into the capsule cavity.When extracting the beverage, the beverage is extracted by injecting pressurized hot water into the capsule, and this capsule is disclosed, for example, in European Patent No. 1792850.

[0068] The resin composition according to the present embodiment is suppressed from deforming and cracking under high temperature and pressure, and therefore can be suitably used to form the beverage extraction capsule. The beverage extraction capsule made from the resin composition according to the present embodiment is less likely to deform or crack during beverage extraction, and therefore can exhibit good beverage extraction properties without the beverage substance leaking out.

[0069] The capsule for extracting beverages can be produced by molding the resin composition by a known molding method, particularly injection molding.

[0070] 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 injection blow molding, gas-assisted molding, injection compression molding, and other injection molding methods. In-mold molding, gas press molding, two-color molding, sandwich molding, push-pull molding, SCORIM molding, and the like can also be used. However, the injection molding methods that can be used are not limited to the above methods.

[0071] The temperature at which the resin is cooled in the mold after injection can be determined as appropriate by a person skilled in the art, but is preferably 20 to 70°C, more preferably 25 to 60°C, even more preferably 30 to 50°C, and particularly preferably 35 to 45°C.

[0072] The resin composition or molded article according to this embodiment has a poly(3-hydroxyalkanoate) resin as its main component and therefore has good seawater degradability, and therefore can solve the environmental problems caused by dumping plastics into the ocean.

[0073] The following items list preferred aspects of the present disclosure, but the present invention is not limited to the following items. [Item 1] A resin composition containing a poly(3-hydroxyalkanoate) resin (A) and an inorganic filler (B), wherein the poly(3-hydroxyalkanoate) resin (A) comprises: a copolymer (A3) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the copolymer having a 3-hydroxybutyrate unit content of 76 mol% or less; and a copolymer (A4) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the copolymer having a weight average molecular weight of 700,000 or more and a 3-hydroxybutyrate unit content of more than 76 mol% and 95 mol% or less; wherein the content of the copolymer (A3) in the content (X) of the poly(3-hydroxyalkanoate) resin (A) excluding the copolymer (A4) is 5% by weight or more and 25% by weight or less; and the content of the copolymer (A4) per 100 parts by weight of the content (X) is 5 parts by weight or more and 30 parts by weight or less; Item 2: The resin composition according to Item 1, wherein the poly(3-hydroxyalkanoate) resin (A) further comprises a copolymer (A1) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the copolymer (A1) having a weight average molecular weight of 100,000 or more and less than 700,000, and a content of 3-hydroxybutyrate units of more than 76 mol % and 95 mol % or less, and the content of the copolymer (A1) in the content (X) is 50 wt % or more and 85 wt % or less. [Item 3] The resin composition according to Item 1 or 2, wherein the poly(3-hydroxyalkanoate) resin (A) further contains a copolymer (A2) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of 3-hydroxybutyrate units being more than 95 mol% and not more than 99 mol%, and the content of the copolymer (A2) in the content (X) is 5% by weight or more and 25% by weight or less. [Item 4] The resin composition according to any of Items 1 to 3, wherein the weight average molecular weight of the copolymer (A4) is 1,000,000 or more.[Item 5] The resin composition according to any one of items 1 to 4, wherein the other hydroxyalkanoate units are 3-hydroxyhexanoate units. [Item 6] The resin composition according to any one of items 1 to 5, wherein the inorganic filler (B) is at least one selected from the group consisting of mica, talc, kaolinite, silica, titanium oxide, and calcium carbonate. [Item 7] A molded article comprising the resin composition according to any one of items 1 to 6. [Item 8] The molded article according to item 7, wherein the molded article is an injection-molded article.

[0074] 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.

[0075] The materials used in the examples and comparative examples are as follows: [Poly(3-hydroxyalkanoate)-based resin] Copolymer (A1): P3HB3HH-1 [poly(3-hydroxybutyrate-3-hydroxyhexanoate), average content ratio 3HB / 3HH = 94.6 / 5.4 (mol% / mol%), weight-average molecular weight 360,000 g / mol] Copolymer (A2): P3HB3HH-2 [poly(3-hydroxybutyrate-3-hydroxyhexanoate), average content ratio 3HB / 3HH = 97.2 / 2.8 (mol% / mol%), weight-average molecular weight 660,000 g / mol] Produced in accordance with the method described in Example 2 of International Publication WO2019 / 142845. Copolymer (A3): P3HB3HH-3 [poly(3-hydroxybutyrate-3-hydroxyhexanoate), average content ratio 3HB / 3HH = 71.8 / 28.2 (mol% / mol%), weight average molecular weight 660,000 g / mol] was produced in accordance with the method described in Example 9 of International Publication WO 2019 / 142845. Copolymer (A4): P3HB3HH-4 [poly(3-hydroxybutyrate-3-hydroxyhexanoate), average content ratio 3HB / 3HH = 89.5 / 10.5 (mol% / mol%), weight average molecular weight 1.2 million g / mol]

[0076] [Inorganic filler (B)] Talc: Microace K-1 (Nippon Talc)

[0077] [Additives] Additive-1: Behenic acid amide (manufactured by Nippon Fine Chemical Co., Ltd.: BNT-22H) Additive-2: Pentaerythritol [manufactured by Mitsubishi Chemical Corporation: Neuraizer P]

[0078] The evaluation methods used in the examples and comparative examples are described below. (Preparation of molding blend) A 75L Super Mixer manufactured by Kawata Co., Ltd. was used to add 500 g to 1 kg (5 to 10 parts by weight) of (A4), 50 g (0.5 part by weight) of Additive-1, and 100 g (1 part by weight) of Additive-2 to a total weight of 10 kg (100% by weight) of (A1), (A2), and (A3) having the blending ratios shown in Table 2, and the mixture was stirred at 300 rpm for 3 minutes to obtain a molding blend.

[0079] (Compounding) A Toshiba Machine TEM26SS (L / D = 60) was used, with the screw configuration, auxiliary equipment, and barrel temperature settings listed in Table 1, and the screw rotation speed was set to 100 rpm. The molding blend was supplied from the base of the screw via main feed 1, and simultaneously, component (B) was supplied from main feed 2 via main feed 2, also from the base of the screw. The total supply rate of main feed 1 and main feed 2 was set to 10 kg / hr, and the respective supply rates of main feed 1 and main feed 2 were determined based on the following formula: Supply rate of main feed 2 = 10 kg / hr × parts by weight of inorganic filler (talc) ÷ total parts by weight of blended components Supply rate of main feed 1 = 10 kg / hr - supply rate of main feed 2 The strand emerging from the die tip was passed through a water tank filled with warm water at 40°C to 45°C to solidify, and then cut using a pelletizer to obtain a pellet-shaped compound.

[0080]

[0081] [Sample Preparation and Various Evaluations] <Method for Measuring Weight-Average Molecular Weight of Components (A1) to (A4)> The weight-average molecular weight of components (A1) to (A4) was measured by first dissolving the resin to be measured in chloroform and heating in a hot water bath at 60°C for 0.5 hours, filtering the soluble portion through a disposable PTFE filter with a 0.2 μm pore size, and then performing GPC measurement using the filtrate under the following conditions: GPC measurement device: Nexera manufactured by Shimadzu Corporation Columns: TSKGelGMHXL (2 columns) and TSKGuardcolumnHXL (1 column) manufactured by Tosoh Corporation Sample concentration: 3 mg / ml Free solution: chloroform solution Free solution flow rate: 1.0 ml / min Sample injection amount: 100 μL Analysis time: 30 minutes Standard sample: standard polystyrene

[0082] <Measurement of Melt Flow Rate (MFR) of Resin Composition> Based on ISO 1133-1, 5 g or more of the pellet-shaped compound was heated at 165° C. for 4 minutes using a melt indexer, and then the melt flow rate (MFR) was measured under a load of 5 kg.

[0083] <Preparation of Dumbbell Test Pieces> Using a dumbbell mold of 168 mm × 20 mm × 4 mm thick, a Toyo Machinery Metal injection molding machine Si-100V was used, with nozzle / T1 / T2 / T3 / T4 = 150 / 150 / 150 / 150 / 150°C and mold temperature set to 35°C, to obtain dumbbell test pieces (168 mm × 20 mm × 4 mm thick).

[0084] <Measurement of Tensile Modulus and Elongation at Break> After leaving the dumbbell test pieces at 23° C. for 30 days, a tensile test was carried out at 20 mm / min in accordance with ISO 527-1 and ISO 527-2 to measure the tensile modulus and elongation at break.

[0085] <Measurement of Breaking Strength at 100°C> After leaving the dumbbell test pieces at 23°C for 30 days, the dumbbell test pieces were subjected to a tensile test at 20 mm / min in a thermostatic chamber at 100°C in accordance with ISO 527-1 and ISO 527-2 to measure the breaking strength.

[0086] <Measurement of fracture energy> After leaving the dumbbell test specimen at 23°C for 30 days, a 2 mm vertical V-notch was made in the center of the dumbbell test specimen, and a bending test was carried out at 100 mm / min in accordance with ISO 178-A, to obtain a graph of test force versus displacement as shown in Figure 1. The fracture energy was measured from the area of ​​the shaded portion under the curve of the obtained graph.

[0087] <Preparation of beverage extraction capsules> A four-cavity coffee capsule mold with a pin gate and hot runner was used, and a Toyo Machinery Metal injection molding machine Si-100V was used, with nozzle / T1 / T2 / T3 = 160 / 160 / 160 / 160°C and the mold temperature set to 40°C, to obtain beverage extraction capsules (thickness 1.2 mm).

[0088] <Evaluation of deformation and cracks during beverage extraction> The obtained beverage extraction capsules were filled with Espresso-grade finely ground coffee powder and closed with aluminum lids designed specifically for capsules. Coffee was then extracted using a coffee machine, and the presence or absence of deformation and cracks in the capsules during coffee extraction was evaluated based on the following criteria: (Deformation) ◯: The capsule was not deformed. ×: The capsule was deformed. (Cracks) ◯: No cracks occurred throughout the capsule. ×: Cracks occurred in the capsule.

[0089] <Pressure resistance test at 85°C> The coffee extraction hole of the beverage extraction capsule obtained as the evaluation sample was sealed with a polyimide film and adhesive, the capsule was covered with a metal plate with an air inlet, and the air inlet was connected to a compressor. Pressurized air was then applied in an environment of 85°C, and the pressure at which the evaluation sample broke was measured.

[0090]

[0091] From Table 2, it can be seen that the resin compositions shown in Examples 1 to 8 have an elastic modulus of 1500 MPa or more and a breaking strength at 100°C higher than that of Comparative Example 1, and are therefore resistant to fracture at high temperatures while maintaining hardness, and have a balance of toughness and strength in high-temperature environments. Furthermore, the capsules for beverage extraction obtained from the resin compositions of Examples 1 to 8 have higher pressure resistance at 85°C than Comparative Examples 1 to 3, and exhibit neither deformation nor cracking during beverage extraction, indicating that deformation and cracking are suppressed under high temperature and pressure.

Claims

1. A resin composition containing a poly(3-hydroxyalkanoate) resin (A) and an inorganic filler (B), wherein the poly(3-hydroxyalkanoate) resin (A) comprises: a copolymer (A3) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the copolymer having a 3-hydroxybutyrate unit content of 76 mol% or less; and a copolymer (A4) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the copolymer having a weight average molecular weight of 700,000 or more and a 3-hydroxybutyrate unit content of more than 76 mol% and 95 mol% or less; wherein the content of the copolymer (A3) in the content (X) of the poly(3-hydroxyalkanoate) resin (A) excluding the copolymer (A4) is 5% by weight or more and 25% by weight or less; and the content of the copolymer (A4) per 100 parts by weight of the content (X) is 5 parts by weight or more and 30 parts by weight or less; A resin composition in which the content of the inorganic filler (B) is 5 parts by weight or more and 40 parts by weight or less per 100 parts by weight of the content (X).

2. The resin composition according to claim 1, wherein the poly(3-hydroxyalkanoate) resin (A) further comprises a copolymer (A1) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the copolymer (A1) having a weight-average molecular weight of 100,000 or more but less than 700,000 and a content of 3-hydroxybutyrate units of more than 76 mol% but not more than 95 mol%, and the content of the copolymer (A1) in the content (X) is 50 wt% or more but not more than 85 wt%.

3. The resin composition according to claim 1 or 2, wherein the poly(3-hydroxyalkanoate) resin (A) further contains a copolymer (A2) of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is more than 95 mol% and not more than 99 mol%; and the content of the copolymer (A2) in the content (X) is 5% by weight or more and 25% by weight or less.

4. The resin composition according to claim 1 or 2, wherein the weight average molecular weight of the copolymer (A4) is 1,000,000 or more.

5. The resin composition according to claim 1 or 2, wherein the other hydroxyalkanoate units are 3-hydroxyhexanoate units.

6. The resin composition according to claim 1 or 2, wherein the inorganic filler (B) is at least one selected from the group consisting of mica, talc, kaolinite, silica, titanium oxide, and calcium carbonate.

7. A molded article comprising the resin composition according to claim 1 or 2.

8. The molded article according to claim 7, wherein the molded article is an injection molded article.

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