Resin composition, film, layered product, and method for producing same

Abstract

This resin composition contains: a copolymer (A) of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, in which the content of the other hydroxyalkanoate unit is 24 mol% or more; a copolymer (B) of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, in which the content of the other hydroxyalkanoate unit is not less than 1 mol% and less than 5 mol%; and a copolymer (C) of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, in which the content of the other hydroxyalkanoate unit is not less than 5 mol% and less than 24 mol%. The weight average molecular weight of the copolymer (A) is 100,000-500,000. At least one of the copolymer (A), the copolymer (B) and the copolymer (C), or all of these copolymers, is a product of a reaction with an organic peroxide.

Description

Resin composition, film, laminate, and method for producing same

[0001] The present invention relates to a resin composition or film containing a poly(3-hydroxyalkanoate) resin, a laminate containing a laminate layer of the resin composition, and a method for producing the same.

[0002] Large amounts of petroleum-derived plastics are discarded every year, and the resulting lack of landfill sites and environmental pollution are becoming serious issues. Microplastics have also become a major problem in the marine environment in recent years. Biodegradable plastics, which decompose in the natural environment, are expected to become more widespread.

[0003] Various types of biodegradable plastics are known (Patent Document 1). In particular, polyhydroxyalkanoate (hereinafter, sometimes referred to as PHA)-based resins, particularly poly(3-hydroxyalkanoate) (hereinafter, sometimes referred to as P3HA)-based resins such as poly(3-hydroxybutyrate) homopolymer resin (hereinafter, sometimes referred to as P3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer resin (hereinafter, sometimes referred to as P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer resin (hereinafter, sometimes referred to as P3HB3HH), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer resin (hereinafter, sometimes referred to as P3HB4HB), have attracted attention due to their excellent seawater degradability.

[0004] Furthermore, laminates produced by laminating PHA onto a biodegradable substrate such as paper are extremely promising from the standpoint of environmental protection, since both the resin and the substrate are highly biodegradable materials. The lamination method can be selected from a method in which the PHA resin is fed into an extruder equipped with a T-die, processed into a film, and then laminated onto a substrate, or an extrusion lamination method in which a PHA resin melted using similar equipment is directly laminated onto a separately unwound substrate without first being formed into a film.

[0005] On the other hand, Patent Document 2 describes that a resin film having a reaction product of a specific amount of an organic peroxide with resin components including P3HB3HH(A) having a 3-hydroxyhexanoate unit content of 1 to 6 mol % and P3HB3HH(B) having a 3-hydroxyhexanoate unit content of 24 mol % or more has good mechanical properties and blocking resistance and can be produced with good productivity.

[0006] JP 2010-200697 A International Publication No. 2022 / 044836

[0007] The inventors have conducted studies and found that when P3HA-based resin is formed into a film using an extruder equipped with a T-die (hereinafter sometimes referred to as T-die film formation), or when extrusion lamination is performed to form a laminate layer of P3HA-based resin directly on a substrate, increasing the processing speed to improve productivity leaves room for improvement, as this results in fluctuations in the thickness of the film or laminate layer in the flow direction (hereinafter sometimes referred to as the MD direction) and the length in the TD direction (the direction perpendicular to the MD direction) becoming smaller relative to the die width (large neck-in).

[0008] In view of the above circumstances, an object of the present invention is to provide a P3HA-based resin composition that can suppress thickness variations and neck-in in the TD direction of the film or laminate layer even when the production speed is increased during T-die film formation or extrusion lamination.

[0009] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors have discovered that by forming a P3HA-based resin composition from three types of P3HB-based copolymers having specific comonomer compositions, controlling the molecular weight of the copolymer having the highest content of other hydroxyalkanoate units within a specific range, and converting at least one of the three types of P3HB-based copolymers into a reaction product with an organic peroxide, it is possible to suppress thickness variations and necking in the TD direction of the film or laminate layer when forming the P3HA-based resin composition into a T-die film or extrusion laminating, even when the production rate is increased, and have completed the present invention.

[0010] That is, the present invention relates to a resin composition containing a poly(3-hydroxyalkanoate)-based resin component, wherein the poly(3-hydroxyalkanoate)-based resin component contains: a copolymer (A) of 3-hydroxybutyrate units and other hydroxyalkanoate units, wherein the content of the other hydroxyalkanoate units is 24 mol% or more; a copolymer (B) of 3-hydroxybutyrate units and other hydroxyalkanoate units, wherein the content of the other hydroxyalkanoate units is 1 mol% or more and less than 5 mol%, and a copolymer (C) of 3-hydroxybutyrate units and other hydroxyalkanoate units, wherein the content of the other hydroxyalkanoate units is 5 mol% or more and less than 24 mol%, wherein the weight-average molecular weight of the copolymer (A) is 100,000 or more and 500,000 or less; and at least one or all of the copolymers (A), (B), and (C) are reaction products with an organic peroxide. The present invention also relates to a film containing the resin composition, and to a laminate including a laminate layer containing the resin composition and a substrate layer. The laminate may be a molded article. The present invention also relates to a method for producing a film, including a step of melt-extrusion molding the resin composition using a T-die, and a method for producing the laminate, including a step of forming the laminate layer on at least one surface of the substrate layer by extrusion lamination. The present invention also relates to a method for producing a laminate, including a step of molding the resin composition into a film, and a step of placing the film on at least one surface of the substrate layer and forming the laminate layer by any of a dry lamination method, a non-solvent lamination method, and a thermal lamination method.

[0011] According to the present invention, even when the production speed is increased during T-die film formation or extrusion lamination, thickness variations and neck-in in the TD direction of the film or laminate layer can be suppressed. Therefore, films with uniform thickness and width, or laminates having laminate layers with uniform thickness and width, can be produced with high productivity. Furthermore, by using such laminates, films or laminates with consistent quality can be produced with high yield.

[0012] Hereinafter, an embodiment of the present invention will be described, but the present invention is not limited to the following embodiment. The resin composition according to this embodiment is a resin composition containing a poly(3-hydroxyalkanoate) resin as an essential component.

[0013] [Poly(3-hydroxyalkanoate) (P3HA) Resin] The poly(3-hydroxyalkanoate) resin contained in the resin composition according to this embodiment is a biodegradable aliphatic polyester (a polyester containing no aromatic ring), and is represented by the general formula: [—CHR—CH ２ 3-hydroxyalkanoic acid repeating units represented by the formula: —CO—O— (wherein R is C ｎ H ２ｎ＋１ where n is an integer of 1 to 15. Among these, polyhydroxyalkanoates containing the repeating unit are preferred, with the repeating unit accounting for 50 mol % or more, and more preferably 70 mol % or more, of the total monomer repeating units (100 mol %).

[0014] Among P3HA-based resins, poly(3-hydroxybutyrate)-based resins (hereinafter sometimes referred to as "P3HB-based resins") can be preferably used because they are particularly easy to obtain and process.

[0015] The P3HB-based resin is an aliphatic polyester resin that can be produced from a microorganism and has 3-hydroxybutyrate (hereinafter, sometimes referred to as "3HB") as a repeating unit. The P3HB-based resin may be a poly(3-hydroxybutyrate) having only 3HB as a repeating unit, or may be a copolymer of 3-hydroxybutyrate and another hydroxyalkanoate. In this embodiment, however, the P3HB-based resin contains at least three types of copolymers having different content ratios of constituent monomers.

[0016] Specific examples of the P3HA-based resin include poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter sometimes referred to as "P3HB3HH"), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (hereinafter sometimes referred to as "P3HB3HV"), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), etc. Among these, poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) are preferred due to ease of industrial production.

[0017] Furthermore, P3HB3HH is preferred from the viewpoints that by changing the composition ratio of the repeating units, it is possible to change the melting point and crystallinity, and thereby change physical properties such as Young's modulus and heat resistance, making it possible to impart physical properties between those of polypropylene and polyethylene, and that it is easy to produce industrially and is a physically useful plastic. In particular, among P3HA-based resins that have the property of being susceptible to thermal decomposition when heated to 180°C or higher, P3HB3HH is preferred from the viewpoint that it can lower the melting point and enable molding and processing at low temperatures.

[0018] Commercially available products of P3HB3HH include Kaneka Biodegradable Polymer Green Planet (registered trademark) manufactured by Kaneka Corporation.

[0019] The melting point, Young's modulus, etc. of P3HB3HV vary depending on the ratio of the 3-hydroxybutyrate component and the 3-hydroxyvalerate component. However, since both components co-crystallize, the degree of crystallinity is high at 50% or more, and although it is more flexible than poly(3-hydroxybutyrate), the improvement in brittleness is insufficient.

[0020] With respect to the entire P3HA-based resin component contained in the resin composition according to this embodiment, the average content ratio of 3-hydroxybutyrate units and other hydroxyalkanoate units to all monomer units constituting the P3HA-based resin component is preferably 3-hydroxybutyrate units / other hydroxyalkanoate units = 99 / 1 to 80 / 20 (mol % / mol %), and more preferably 97 / 3 to 85 / 15 (mol % / mol %), from the viewpoint of achieving both strength and productivity of the laminate layer of the film or laminate.

[0021] The average content ratio of each monomer unit in all monomer units constituting the P3HA-based resin component can be determined by a method known to those skilled in the art, for example, the method described in paragraph

[0047] of WO 2013 / 147139. The average content ratio means the molar ratio of each monomer unit in all monomer units constituting the P3HA-based resin component, that is, the molar ratio of each monomer unit contained in the entire P3HA-based resin mixture.

[0022] The P3HA resin component contained in the resin composition according to this embodiment includes three types of P3HA resins having different content ratios of constituent monomers, as shown below: (A) a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content ratio of other hydroxyalkanoate units is 24 mol% or more, (B) a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content ratio of other hydroxyalkanoate units is 1 mol% or more and less than 5 mol%, and (C) a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content ratio of other hydroxyalkanoate units is 5 mol% or more and less than 24 mol%.

[0023] As described above, examples of the other hydroxyalkanoate units contained in copolymer (A), copolymer (B), and copolymer (C) include 3-hydroxyhexanoate units, 3-hydroxyvalerate units, 4-hydroxybutyrate units, 3-hydroxyoctanoate units, and 3-hydroxyoctadecanoate units. Only one type of other hydroxyalkanoate unit may be contained, or two or more types may be contained. Furthermore, the other hydroxyalkanoate units contained in copolymer (A), copolymer (B), and copolymer (C) may be the same or different. In particular, it is preferable that the other hydroxyalkanoate unit in at least one or all of copolymer (A), copolymer (B), and copolymer (C) is 3-hydroxyhexanoate.

[0024] Copolymer (A) is a low-crystalline P3HA-based resin, copolymer (B) is a high-crystalline P3HA-based resin, and copolymer (C) is a medium-crystalline P3HA-based resin whose crystallinity is intermediate between that of copolymer (A) and copolymer (B).

[0025] In general, highly crystalline P3HA-based resins have excellent productivity but poor mechanical strength, while low-crystalline P3HA-based resins have poor productivity but excellent mechanical properties. It is presumed that when both resins are used in combination, the highly crystalline P3HA-based resin forms fine resin crystal particles, while the low-crystalline P3HA-based resin forms tie molecules that crosslink the resin crystal particles. The combined use of the above three types of resins can improve the strength and productivity of the laminate layer of a film or laminate.

[0026] The use of a low-crystalline copolymer (A) can particularly improve the crack resistance of the film or laminate layer. The content of 3-hydroxybutyrate units in copolymer (A) is preferably lower than the average content of 3-hydroxybutyrate units in all monomer units constituting the P3HA-based resin component. The content of other hydroxyalkanoate units in copolymer (A) is preferably 24 mol% or more and 99 mol% or less, more preferably 24 mol% or more and 50 mol% or less, even more preferably 24 mol% or more and 35 mol% or less, and particularly preferably 24 mol% or more and 30 mol% or less.

[0027] The copolymer (A) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0028] On the other hand, the use of a highly crystalline copolymer (B) can improve the handleability of the copolymer (A). The content of 3-hydroxybutyrate units in the copolymer (B) is preferably higher than the average content of 3-hydroxybutyrate units in all monomer units constituting the P3HA-based resin component. The content of other hydroxyalkanoate units in the copolymer (B) is preferably 1 mol% or more and less than 5 mol%, more preferably 2 mol% or more and 4 mol% or less.

[0029] The copolymer (B) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0030] The proportion of each copolymer relative to the total of copolymer (A) and copolymer (B) is not particularly limited, but it is preferable that the proportion of copolymer (A) is 40% by weight or more and 90% by weight or less, and the proportion of copolymer (B) is 10% by weight or more and 60% by weight or less, and it is more preferable that the proportion of copolymer (A) is 55% by weight or more and 75% by weight or less, and the proportion of copolymer (B) is 25% by weight or more and 45% by weight or less.

[0031] Furthermore, the content of copolymer (A) relative to the total amount of P3HA-based resin components contained in the resin composition according to this embodiment is preferably 15% by weight or more and 45% by weight or less. Within this range, the effect of copolymer (A) is more easily exhibited, and even when the production rate is increased, the effect of suppressing thickness fluctuations of the film or laminate layer and neck-in in the TD direction is more easily realized. The lower limit is more preferably 20% by weight or more, even more preferably 25% by weight or more, and particularly preferably 27% by weight or more, so that thickness fluctuations and neck-in of the film or laminate layer can be further suppressed. The upper limit is more preferably 43% by weight or less.

[0032] By using copolymer (C) in addition to copolymer (A) and copolymer (B), the solidification of the P3HA resin component is accelerated, thereby increasing the production speed of T-die film formation and extrusion lamination. The content of other hydroxyalkanoate units in copolymer (C) is preferably 5 mol% or more and less than 24 mol%, more preferably 5 mol% or more and 22 mol% or less, even more preferably 6 mol% or more and 20 mol% or less, and particularly preferably 6 mol% or more and 18 mol% or less. The upper limit may be 15 mol% or less, or may be 10 mol% or less.

[0033] The copolymer (C) 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 proportion of copolymer (C) relative to the total of copolymer (A), copolymer (B), and copolymer (C) is not particularly limited, but is preferably 1% by weight or more and 99% by weight or less, more preferably 5% by weight or more and 90% by weight or less, and even more preferably 8% by weight or more and 85% by weight or less. The lower limit may be 20% by weight or more, 30% by weight or more, or 40% by weight or more. The upper limit may be 80% by weight or less, or 70% by weight or less. In order to further suppress thickness fluctuation and neck-in of the film or laminate layer, the proportion of copolymer (C) is preferably 60% by weight or less, more preferably 55% by weight or less, and even more preferably 50% by weight or less.

[0035] The method for obtaining a blend of multiple P3HA-based resins is not particularly limited, and may be a method for obtaining a blend by microbial production or a method for 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 the resins.

[0036] The weight average molecular weight of the entire P3HA-based resin component is not particularly limited, but from the viewpoint of achieving both strength and productivity of the film or laminate layer, it is preferably from 100,000 to 2,000,000, more preferably from 150,000 to 1,000,000, and particularly preferably from 200,000 to 500,000. The upper limit may be 400,000 or less, or may be 300,000 or less.

[0037] The weight-average molecular weight of the copolymer (A), which is a low-crystalline resin, is set to 100,000 or more and 500,000 or less. By limiting the weight-average molecular weight of the copolymer (A) to 500,000 or less, even if the production speed is increased during T-die film formation or extrusion lamination of the resin composition, thickness fluctuations and neck-in of the film or laminate layer can be suppressed, and high productivity can be achieved. On the other hand, by ensuring the weight-average molecular weight of the copolymer (A) to 100,000 or more, the strength of the film or laminate layer can be ensured while ensuring productivity. It is preferably 150,000 or more and 450,000 or less, more preferably 200,000 or more and 400,000 or less. The lower limit may be 250,000 or more, or 300,000 or more.

[0038] The weight-average molecular weight of each of the copolymers (B) and (C) is not particularly limited. However, the weight-average molecular weight of the copolymer (B) is preferably 200,000 or more and 1,000,000 or less, more preferably 220,000 or more and 800,000 or less, and even more preferably 250,000 or more and 600,000 or less. The upper limit may be 500,000 or less, or may be 400,000 or less.

[0039] The weight average molecular weight of the copolymer (C) is preferably from 100,000 to 2,500,000, more preferably from 150,000 to 2,000,000, and even more preferably from 200,000 to 1,500,000. The upper limit may be 1,000,000 or less, 500,000 or less, 400,000 or less, or 300,000 or less.

[0040] The weight average molecular weight of the P3HA resin described above is a value measured on the P3HA resin before it is reacted with the organic peroxide.

[0041] The weight-average molecular weight can be measured using gel permeation chromatography (GPC) (Shimadzu Corporation's "High Performance Liquid Chromatograph 20A System"), using polystyrene gel (Showa Denko K.K.'s "K-G 4A" and "K806M") as the column, and chloroform as the mobile phase, and can be determined as the molecular weight in terms of polystyrene. In this case, a calibration curve is prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. As the column for the GPC, a column appropriate for measuring the molecular weight may be used.

[0042] [Organic Peroxide] In the poly(3-hydroxyalkanoate)-based resin component contained in the resin composition according to this embodiment, at least one or all of the copolymers (A), (B), and (C) are modified by reaction with an organic peroxide. This makes it possible to suppress thickness variations and neck-in of the film or laminate layer even when the production rate is increased during T-die film formation or extrusion lamination of the resin composition, thereby achieving high productivity. In particular, since the effect of suppressing thickness variations and neck-in is significant, it is preferable that at least the copolymer (A), which is a low-crystalline resin, is a reaction product with an organic peroxide.

[0043] The copolymers (B) and (C) may be either reactants with an organic peroxide or unmodified products that have not been reacted with an organic peroxide. However, it is advantageous in terms of production of the resin composition that the copolymer (B) and the copolymer (A) are reactants with an organic peroxide.

[0044] The copolymer (C) may be either a reactant or an unmodified product. From the viewpoint of improving the crack resistance of the film or laminate layer and suppressing neck-in in the TD direction, the copolymer (C) is preferably a reactant. Furthermore, from the viewpoint of suppressing the melt viscosity of the resin composition to improve processability and more easily suppressing thickness fluctuations during high-speed production, the copolymer (C) is preferably an unreacted product.

[0045] Examples of the organic peroxides include diisobutyl peroxide, cumyl peroxyneodecanoate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, t-butylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl)peroxydicarbonate, bis(2-ethylhexyl)peroxydicarbonate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, di(3,5,5-trimethylhexanoyl)peroxide, dilauroyl peroxide, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, bis(4-t-butylcyclohexyl)peroxydicarbonate, bis(2-ethylhexyl)peroxydicarbonate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxyneoheptanoate, t-hexylperoxypivalate, t-butylperoxypivalate, di(3,5,5-trimethylhexanoyl)peroxide, dilauroyl peroxide, t-butylperoxy-2-ethylhexanoate, disuccinic acid peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxy isopropyl carbonate, 1,6-bis(t-butylperoxycarbonyloxy)hexane, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyacetate, t-butylperoxybenzoate, t-amylperoxy-3,5,5-trimethylhexanoate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 2,2-di-t-butylperoxybutane, and the like. Among these, t-butylperoxy 2-ethylhexyl carbonate, t-butylperoxy isopropyl carbonate, and t-butylperoxy 2-ethylhexanoate are preferred. The organic peroxides may be used alone or in combination of two or more.

[0046] The amount of the organic peroxide used can be appropriately set taking into consideration the effects of the invention, but the total amount of the organic peroxide used in the resin composition is preferably 1.0 part by weight or less, particularly preferably 0.8 part by weight or less, relative to 100 parts by weight of copolymer (A). The lower limit is preferably 0.1 part by weight or more, more preferably 0.2 part by weight or more, and more preferably 0.3 part by weight or more. From the viewpoint of suppressing neck-in in the TD direction and improving the crack resistance of the film or laminate layer, the amount is preferably 0.35 part by weight or more, more preferably 0.40 part by weight or more, and particularly preferably 0.50 part by weight or more.

[0047] The weight-average molecular weight of the P3HA-based resin after the reaction with the organic peroxide is preferably in the range of about 50,000 to 150,000 higher than the weight-average molecular weight of the P3HA-based resin before the reaction as described above. The method for measuring the weight-average molecular weight is as described above.

[0048] The weight average molecular weight of the copolymer (A) after reaction with the organic peroxide is preferably about 150,000 to about 650,000, more preferably about 200,000 to about 600,000, and particularly preferably about 250,000 to about 550,000. The lower limit may be 300,000 or more.

[0049] The weight-average molecular weight of the entire P3HA-based resin component including the copolymer after reaction with the organic peroxide is preferably 150,000 to 2,500,000, more preferably 200,000 to 1,500,000, and particularly preferably 250,000 to 600,000. By setting the weight-average molecular weight to 150,000 or more, the strength of the film or laminate layer tends to be further improved. On the other hand, by setting the weight-average molecular weight to 2,500,000 or less, processability tends to be further improved and molding tends to be easier.

[0050] The content of the P3HA-based resin component in the resin composition according to this embodiment is not particularly limited, but is preferably 20% by weight or more, more preferably 30% by weight or more, even more preferably 40% by weight or more, even more preferably 60% by weight or more, and particularly preferably 70% by weight or more. By making the content of the P3HA-based resin component 20% by weight or more, the biodegradability of the resin composition tends to be even better. The upper limit of the content of the P3HA-based resin component is not particularly limited, but may be 100% by weight or less, or may be 99% by weight or less.

[0051] [Other Resins] The resin composition according to this embodiment may contain a resin other than the P3HA-based resin (sometimes referred to as "other resin"). The other resin is not particularly limited as long as it does not significantly reduce compatibility, moldability, or mechanical properties during molding. However, when the resin composition is used in an application requiring biodegradability, which is a characteristic of P3HA-based resins, a biodegradable resin is preferred. Examples of other resins include aliphatic polyesters formed by polycondensation of aliphatic diols and aliphatic dicarboxylic acids, and aliphatic-aromatic polyesters containing both aliphatic and aromatic compounds as monomers. Examples of the former include polyethylene succinate, polybutylene succinate (PBS), polyhexamethylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polybutylene succinate adipate (PBSA), polyethylene sebacate, and polybutylene sebacate. Examples of the latter include poly(butylene adipate-co-butylene terephthalate) (PBAT), poly(butylene sebacate-co-butylene terephthalate), poly(butylene azelate-co-butylene terephthalate), poly(butylene succinate-co-butylene terephthalate) (PBST), etc. One type of other resin can be used alone, or two or more types can be used in combination.

[0052] The content of the other resin in the resin composition according to this embodiment is not particularly limited, but is preferably 250 parts by weight or less, more preferably 100 parts by weight or less, and even more preferably 50 parts by weight or less, relative to 100 parts by weight of the total amount of the P3HA-based resin components. It may also be 30 parts by weight or less, 10 parts by weight or less, or 5 parts by weight or less. The lower limit of the content of the other resin is not particularly limited, and may even be 0 parts by weight.

[0053] [Other Components (Additives)] The resin composition according to this embodiment may contain other components (additives). Examples of such additives include colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolite, fragrances such as vanillin and dextrin, fillers, plasticizers, antioxidants, weather resistance improvers, UV absorbers, crystal nucleating agents, lubricants, release agents, water repellents, antibacterial agents, and sliding properties improvers. Only one type of additive may be contained, or two or more types may be contained. The content of these additives can be appropriately determined by those skilled in the art depending on the intended use. Crystal nucleating agents, lubricants, fillers, and plasticizers will be described in more detail below.

[0054] (Nucleating Agent) The resin composition may also contain a nucleating agent. Examples of nucleating agents include polyhydric alcohols such as pentaerythritol, galactitol, and mannitol; orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, and boron nitride. Among these, pentaerythritol is preferred because of its particularly excellent effect of promoting the crystallization of poly(3-hydroxyalkanoate)-based resins. One or more nucleating agents may be used, and the ratio of their use can be appropriately adjusted depending on the purpose. The amount of nucleating agent used is not particularly limited, but is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, and even more preferably 0.7 to 1.5 parts by weight, per 100 parts by weight of the total amount of the P3HA-based resin components.

[0055] (Lubricant) The resin composition may also contain a lubricant. 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 is preferred because of its particularly excellent lubricating effect on P3HA-based resins. One or more types of lubricants may be used, and the usage ratio can be appropriately adjusted depending on the purpose. 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 the P3HA-based resin components.

[0056] (Filler) The resin composition may contain a filler. By including a filler, the strength of the film or laminate layer can be increased. The filler may be either an inorganic filler or an organic filler, or both may be used in combination. The inorganic filler is not particularly limited, but examples thereof include silicates, carbonates, sulfates, phosphates, oxides, hydroxides, nitrides, and carbon black. Only one type of inorganic filler may be used, or two or more types may be used in combination.

[0057] The content of the filler is not particularly limited, but is preferably 1 to 100 parts by weight, more preferably 3 to 80 parts by weight, even more preferably 5 to 70 parts by weight, and even more preferably 10 to 60 parts by weight, relative to 100 parts by weight of the total amount of the P3HA-based resin components. However, the resin composition does not have to contain a filler.

[0058] (Plasticizer) The resin composition may contain a plasticizer. The plasticizer is not particularly limited, but from the viewpoint of compatibility with the P3HA-based resin, it is preferable to use an ester compound having an ester bond in the molecule.

[0059] 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, phthalate ester compounds, citrate ester compounds, sebacate ester compounds, isosorbide ester compounds, and polycaprolactone compounds. Among these, modified glycerin compounds, dibasic acid ester compounds, adipate compounds, polyether ester compounds, citrate ester compounds, sebacate ester compounds, and isosorbide ester compounds are preferred, with modified glycerin compounds being particularly 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.

[0060] 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 the P3HA resin component, 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 Co., Ltd.'s "Rikemal" (registered trademark) PL series and "BIOCIZER" (registered trademark).

[0061] 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.

[0062] Examples of the adipate compounds include diethylhexyl adipate, dioctyl adipate, and diisononyl adipate.

[0063] Examples of polyether ester compounds include polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate.

[0064] Examples of citrate ester compounds include tributyl acetyl citrate.

[0065] Examples of the sebacate ester compounds include dibutyl sebacate.

[0066] As the ester compound, glycerin diester is preferred, glycerin diacetomonoester is more preferred, and glycerin diacetomonolaurate is more preferred, particularly from the viewpoint of compatibility with the P3HA-based resin.

[0067] The amount of plasticizer is preferably 0.1 parts by weight or more and less than 20.0 parts by weight per 100 parts by weight of the total amount of the P3HA-based resin components. By adding 0.1 parts by weight or more of plasticizer, the strength of the film or laminate layer can be improved and the laminate can be given sufficient strength for practical use. Furthermore, by adding less than 20.0 parts by weight of plasticizer, the productivity of the film or laminate can be improved. However, the resin composition does not need to contain a plasticizer. The lower limit is preferably 0.2 parts by weight or more, more preferably 0.3 parts by weight or more. The upper limit is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and even more preferably 1 part by weight or less.

[0068] [Melt Viscosity and Drawdown Time] In the present application, the melt viscosity (η) and drawdown time (t) of the resin composition according to this embodiment are defined as follows: Melt viscosity (η): measured using a capillary rheometer equipped with an orifice having a radius of 1 mm and a capillary length of 10 mm at the end of a barrel having a furnace body diameter of 0.955 mm, at a barrel setting temperature of 170°C and a volumetric flow rate of 0.716 cm ３ / min, shear rate 122 sec －１ Drawdown time (t): the time required for the resin composition discharged from the orifice to fall 20 cm when measuring the melt viscosity.

[0069] The melt viscosity (η) of the resin composition according to this embodiment may be appropriately set and is not particularly limited. However, the upper limit of the melt viscosity is preferably 1000 (Pa s) or less, more preferably 600 (Pa s) or less, and particularly preferably 500 (Pa s) or less, in order to suppress the resin pressure during T-die film formation or extrusion lamination and stabilize production. The lower limit of the melt viscosity is preferably 300 (Pa s) or more, more preferably 350 (Pa s) or more, and particularly preferably 400 (Pa s) or more, in order to increase the entanglement of molecular chains during T-die film formation or extrusion lamination and more easily suppress thickness fluctuations of the film or laminate layer and neck-in in the TD direction. The melt viscosity can be controlled within the above range by, for example, the amount of organic peroxide used, the molecular weight of each copolymer or the entire P3HA-based resin component, the proportion of each copolymer used, etc.

[0070] The drawdown time (t) of the resin composition according to this embodiment may be set appropriately and is not particularly limited. However, the upper limit of the drawdown time is preferably 45 seconds or less, more preferably 40 seconds or less, and particularly preferably 35 seconds or less. The lower limit is preferably 10 seconds or more, more preferably 14 seconds or more, and particularly preferably 20 seconds or more. By setting the drawdown time within the above range, thickness fluctuation and neck-in tend to be more easily suppressed during T-die film formation or extrusion lamination. The drawdown time can be controlled within the above range by adjusting the amount of organic peroxide used, the molecular weight of each copolymer or the entire P3HA-based resin component, the proportion of each copolymer used, and the like.

[0071] In the resin composition according to this embodiment, the ratio (t / η) of the drawdown time (t, sec) to the melt viscosity (η, Pa s) is 3.4 × 10 －２ (sec / [Pa・s]) or more 8.0×10 －２ (sec / [Pa s]) or less. The upper limit is 7.5 × 10 －２ (sec / [Pa s]) or less, and more preferably 7.0 × 10 －２(sec / [Pa s]) or less is particularly preferable. The lower limit is 3.5 × 10 －２ (sec / [Pa s]) or more, and more preferably 4.0 × 10 －２ (sec / [Pa s]) or more is more preferable, and 5.0 × 10 －２ (sec / [Pa·s]) or more is particularly preferred.

[0072] When the ratio of the drawdown time (t) to the melt viscosity (η) is within the above range, the melt viscosity and melt tension of the resin composition are properly balanced in T-die film formation or extrusion lamination, which tends to suppress thickness variation and necking-in and make it easier to produce a film or laminate layer with a uniform film thickness and width.

[0073] <Method for Producing Resin Composition> The resin composition according to this embodiment can be produced by a method including at least a step of reacting a part of the P3HA-based resin component or all of the P3HA-based resin component with an organic peroxide. Although the reason is unclear, a resin composition including a reaction product obtained by reacting at least one or all of the copolymers (A), (B), and (C) with an organic peroxide can produce a film or laminate layer that can be suitably used in a laminate.

[0074] The reaction between the P3HA resin and the organic peroxide can be carried out by melt-kneading them in an extruder (a "melt-kneading step"), or by reacting the P3HA resin with the organic peroxide in a solution or aqueous dispersion of the P3HA resin (an "in-liquid reaction step").

[0075] In the melt-kneading step, the organic peroxide can be added in various forms, such as a solid or a liquid. It may also be added in the form of a solution or dispersion of the organic peroxide diluted with a diluent or the like. In particular, when an ester compound is blended as a plasticizer, an organic peroxide in a form that can be mixed with the ester compound (particularly an organic peroxide that is liquid at room temperature (25°C)) is preferred because it can be uniformly dispersed in the P3HA-based resin and makes it easier to suppress local modification reactions in the resin composition.

[0076] The P3HA resin used in the melt-kneading step may be at least one or all of copolymer (A), copolymer (B), and copolymer (C). It is particularly preferable to use copolymer (A) and, optionally, copolymer (B) and / or (C). It is preferable to use each copolymer that has not been reacted with an organic peroxide.

[0077] In the melt-kneading step, the P3HA resin and the organic peroxide are fed into an extruder and melt-kneaded, but other components such as the crystal nucleating agent, external lubricant, filler, plasticizer, etc., as described above, may also be fed into the extruder in addition to these components and melt-kneaded. However, in this embodiment, it is preferable to perform melt-kneading without adding a crosslinking agent having two or more radically reactive functional groups (e.g., epoxy groups or carbon-carbon double bonds) as disclosed in U.S. Patent No. 9,034,989.

[0078] In the melt-kneading step, the P3HA resin, the organic peroxide, and optionally other components may be fed separately into the extruder, or the components may be mixed and then fed into the extruder. It is particularly preferred to feed the organic peroxide and the P3HA resin separately into the extruder. This feeding method improves the dispersibility of the organic peroxide, making it less likely for lumps to form in the resulting molded product, and thus facilitating stable, high-quality T-die film formation or extrusion lamination.

[0079] In the melt-kneading step, all of the P3HA-based resin component may be reacted with the organic peroxide. Alternatively, a portion of the P3HA-based resin component may be reacted with the organic peroxide to form a reaction product, and the remaining P3HA-based resin may be added to the reaction product and further melt-kneaded. In this case, the remaining P3HA-based resin added later does not react with the organic peroxide. From the viewpoints of productivity and property improvement, it is preferable to react a portion of the P3HA-based resin component with the organic peroxide and then add the remaining P3HA-based resin.

[0080] The melt-kneading in the melt-kneading step can be carried out according to a known or conventional method, and can be carried out using, for example, an extruder (single-screw extruder, twin-screw extruder), a kneader, etc. The melt-kneading conditions are not particularly limited and can be set appropriately, but it is preferable to set a resin temperature and residence time that allow the organic peroxide to complete the reaction during melt-kneading. Specifically, the upper limit of the resin temperature measured with a die thermometer is preferably 190°C or less, more preferably 180°C or less, and particularly preferably 170°C or less, and the lower limit is preferably 120°C or more, more preferably 125°C or more, and particularly preferably 130°C or more. Furthermore, the upper limit of the residence time in the extruder is preferably 700 seconds or less, more preferably 500 seconds or less, and particularly preferably 300 seconds or less, and the lower limit is preferably 40 seconds or more, more preferably 50 seconds or more, and particularly preferably 60 seconds or more.

[0081] The resin temperature and residence time are affected by the set temperature of the extruder, the screw rotation speed, and the screw configuration. For example, the residence time at a resin temperature of 180 ° C. is 20 seconds or more, or the residence time at a resin temperature of 170 ° C. is 60 seconds or more. It is preferable to provide a barrel zone where the barrel set temperature of the extruder is 150 ° C. or more and 180 ° C. or less in more than half of the extruder, and set the screw rotation speed to 80 rpm or more and 200 rpm or less. On the other hand, since deterioration of the P3HA-based resin may be accelerated when the resin temperature exceeds 180 ° C., it is preferable to set the barrel zone where the barrel set temperature of the extruder is 120 ° C. or more and 160 ° C. or less in less than half of the extruder so that the residence time at a resin temperature of 180 ° C. is not 60 seconds or more. In order to facilitate pelletization of the resin coming out of the die (for example, pelletization by strand cutting, underwater cutting, etc.), it is preferable to set the die temperature to, for example, 120 ° C. or more and 160 ° C. or less, to reduce poor cutting due to insufficient solidification and adhesion of pellets to each other.

[0082] The resin composition according to this embodiment can be further molded (molded) to obtain various molded articles (molded articles obtained by molding the lamination resin composition according to this embodiment). In particular, the resin composition according to this embodiment can be suitably used in the production of films for producing laminates, or in methods for producing laminates by directly extrusion laminating onto a substrate. Therefore, laminates produced by film attachment or extrusion lamination can be suitably produced.

[0083] <Method for Producing Laminate> The laminate produced using the resin composition according to this embodiment is not particularly limited, and can be produced, for example, by forming a resin layer (laminate layer) containing a P3HA-based resin on one or both sides of a substrate layer such as paper by a lamination method. The lamination method is a method for producing a laminate by using a pressure-bonding surface to press-bond the resin layer containing a P3HA-based resin to the substrate layer, and then peeling the resin layer containing a P3HA-based resin from the pressure-bonding surface. The pressure-bonding surface may be any surface that can press-bond the resin layer containing a P3HA-based resin to the substrate layer, and examples of the surface include a plate-like surface and the surface of a roll.

[0084] The lamination method is not particularly limited, but specific examples include an extrusion lamination method in which a resin composition containing a molten P3HA-based resin is extruded from a T-die into a film, directly laminated onto a separately unwound substrate layer such as paper, and cooled and pressed using a cooling roll; and a lamination method (specifically, a thermal lamination method, a dry lamination method, or a non-solvent lamination method) in which a film containing a P3HA-based resin that has been prepared in advance by melt extrusion molding using a T-die is placed on the surface of the substrate layer and pressed.

[0085] (Substrate Layer) The substrate layer is not particularly limited as long as it can be laminated with the resin composition according to this embodiment. From the viewpoint of enhancing the biodegradability of the entire laminate, the substrate layer is preferably a biodegradable layer. In this application, biodegradability refers to the property of the material being decomposed into water and carbon dioxide by the action of microorganisms. Examples of biodegradable substrate layers include, but are not limited to, paper (mainly composed of cellulose), cellophane, cellulose esters; polyvinyl alcohol, polyamino acids, polyglycolic acid, pullulan, etc. Paper or cellophane is preferred, with paper being particularly preferred, due to its excellent heat resistance and low cost. The type of paper is not particularly limited and can be selected appropriately depending on the application of the laminate. Specific examples include cup base paper, kraft paper with various treatments such as unbleached, bleached, and one-sided gloss, fine paper, coated paper, tissue paper, glassine paper, and paperboard. The paper may contain additives such as water-resistant agents, water-repellents, and inorganic substances, as needed.

[0086] The substrate layer may be previously subjected to a surface treatment such as a corona treatment, a plasma treatment, a flame treatment, an anchor coat treatment, etc. These surface treatments may be performed alone or in combination.

[0087] When a resin layer containing a P3HA-based resin is formed by the lamination method, the heating temperature in the lamination method (hereinafter also referred to as the lamination temperature) is preferably a temperature in the range of the resin composition according to this embodiment during lamination, which is equal to or higher than the melting point (Tm) of the resin composition and less than a temperature 30°C higher than the melting point (Tm). The melting point refers to the top temperature of the melting point peak on the highest temperature side in the crystalline melting curve obtained by differential scanning calorimetry. If the lamination temperature is lower than the melting point, the resin cannot be sufficiently fluidized, and the adhesive strength with the base material layer tends to be insufficient. Furthermore, if the lamination temperature is 30°C higher than the melting point, the solidification rate of the resin layer after lamination slows, and as a result, the peelability from the pressure-bonded surface tends to be insufficient. Specifically, the lamination temperature is preferably 160°C or higher, more preferably 165°C or higher, and particularly preferably 170°C or higher. Furthermore, the upper limit of the lamination temperature is preferably 180°C or lower. When the lamination temperature is 180° C. or less, it tends to be possible to avoid a decrease in the mechanical strength of the laminate layer due to thermal decomposition of the P3HA-based resin.

[0088] The lamination temperature may be set so that the temperature of the resin composition containing the P3HA resin is within the above range during lamination. For example, in the case of extrusion lamination, the temperature of the T-die may be adjusted, and in the case of thermal lamination, the temperature of the heating roll used to bond the films may be adjusted.

[0089] The surface temperature of the chill roll in the extrusion lamination method is not particularly limited as long as it is a temperature at which the resin layer can be cooled and pressure-bonded, and can be determined appropriately. The surface temperature of the chill roll may be, for example, 20 to 70°C, and preferably 40 to 60°C. When the surface temperature is within the above range, crystallization of the P3HA-based resin component is promoted, resulting in reduced adhesion to the chill roll and achieving solidification in a short period of time.

[0090] The thickness of the film according to this embodiment or the thickness of the laminate layer of the laminate according to this embodiment is not particularly limited, but from the viewpoint of preventing water absorption into the paper base layer while ensuring sufficient flexibility, it is preferably 5 to 300 μm, and more preferably 10 to 200 μm.

[0091] [Molded Product] A molded product (hereinafter also referred to as the present molded product) can be produced using the laminate according to this embodiment. The present molded product is formed from a laminate having a uniform thickness or width of the laminate layer, and is therefore highly productive and advantageous in a variety of applications.

[0092] The present molded article is not particularly limited as long as it contains the present laminate, and examples thereof include paper, film, sheet, tube, plate, rod, container (e.g., bottle container), bag, part, etc. From the viewpoint of measures against marine pollution, the present molded article is preferably a bag or a bottle container.

[0093] In one embodiment of the present invention, the molded article may be the laminate itself or a product obtained by secondary processing using the laminate. By processing the laminate, the molded article containing the laminate can be suitably used as various packaging container materials such as shopping bags, various bags, food and confectionery packaging materials, cups, trays, cartons, etc. (in other words, in various fields such as food, cosmetics, electronics, medicine, and pharmaceuticals). Because the laminate contains a resin composition that has high adhesion to substrates and good heat resistance, it is more suitable as a container for holding liquids, particularly hot contents, such as cups for food and beverages such as instant noodles, instant soup, and coffee, and trays for prepared meals, bento boxes, and microwaveable foods.

[0094] The various secondary processes described above can be carried out in the same manner as conventional resin-laminated paper, i.e., using various bag-making machines, filling and packaging machines, etc. Processing can also be carried out using machines such as paper cup forming machines, punching machines, box making machines, etc. In these processing machines, known techniques can be used to bond the laminate, such as heat sealing, impulse sealing, ultrasonic sealing, high-frequency sealing, hot air sealing, and frame sealing.

[0095] The heat-sealing temperature of the present laminate varies depending on the adhesion method. When a heat-sealing tester with a seal bar is used, the heat-sealing temperature of the present laminate is usually 250°C or less, preferably 200°C or less, and more preferably 180°C or less. Within the above range, melting of the resin near the sealed portion can be avoided, and an appropriate resin layer thickness and seal strength can be ensured. Furthermore, when a heat-sealing tester with a seal bar is used, the lower limit is usually 130°C or more, preferably 140°C or more, and more preferably 150°C or more. Within the above range, appropriate adhesion at the sealed portion can be ensured.

[0096] The heat-sealing pressure of the present laminate varies depending on the bonding method. When a heat-sealing tester with a seal bar is used, the heat-sealing pressure of the present laminate is usually 0.1 MPa or more, preferably 0.3 MPa or more. Within this range, appropriate adhesion at the sealed portion can be ensured. Furthermore, when a heat-sealing tester with a seal bar is used, the upper limit is usually 0.5 MPa or less, preferably 0.45 MPa or less. Within this range, thinning of the film thickness at the sealed end can be avoided, and seal strength can be ensured.

[0097] In one embodiment of the present invention, the present molded article can be composited with a molded article made of a material different from the present molded article (for example, fiber, thread, rope, woven fabric, knitted fabric, nonwoven fabric, paper, film, sheet, tube, plate, rod, container, bag, part, foam, etc.) in order to improve its physical properties. These materials are also preferably biodegradable.

[0098] Each of the following items lists 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)-based resin component, wherein the poly(3-hydroxyalkanoate)-based resin component contains: a copolymer (A) of 3-hydroxybutyrate units and other hydroxyalkanoate units, wherein the content of the other hydroxyalkanoate units is 24 mol% or more; a copolymer (B) of 3-hydroxybutyrate units and other hydroxyalkanoate units, wherein the content of the other hydroxyalkanoate units is 1 mol% or more and less than 5 mol%, and a copolymer (C) of 3-hydroxybutyrate units and other hydroxyalkanoate units, wherein the content of the other hydroxyalkanoate units is 5 mol% or more and less than 24 mol%, wherein the weight average molecular weight of the copolymer (A) is 100,000 or more and 500,000 or less; and at least one or all of the copolymers (A), (B), and (C) are reaction products with an organic peroxide. [Item 2] The resin composition according to Item 1, wherein the content of the copolymer (A) relative to the total amount of the poly(3-hydroxyalkanoate)-based resin components is 15% by weight or more and 45% by weight or less. [Item 3] The resin composition according to Item 1 or 2, wherein at least the copolymer (A) is a reaction product with the organic peroxide. [Item 4] The resin composition according to any one of Items 1 to 3, wherein the total amount of the organic peroxide used in the resin composition is 0.1 parts by weight or more and 1.0 parts by weight or less per 100 parts by weight of the copolymer (A). [Item 5] The resin composition according to any one of Items 1 to 4, wherein the resin composition has a melt viscosity [η] of 300 Pa s or more and 1,000 Pa s or less. Melt viscosity: Using a capillary rheometer having a furnace body diameter of 0.955 mm and an orifice with a radius of 1 mm and a capillary length of 10 mm attached to the end thereof, the melt viscosity [η] was measured at a barrel setting temperature of 170°C and a volume flow rate of 0.716 cm. ３ / min, shear rate 122 sec －１[Item 6] The resin composition according to any one of Items 1 to 5, wherein the resin composition has a drawdown time of 14 seconds or more and 45 seconds or less. Drawdown time: the time required for the resin composition discharged from an orifice to fall 20 cm when measuring the melt viscosity. [Item 7] The resin composition has a ratio (t / η) of the drawdown time [t] to the melt viscosity [η] of 3.4 × 10 －２ ((sec / [Pa・s]) or more 8.0×10 －２ The resin composition according to any one of items 1 to 6, wherein the melt viscosity is 0.716 cm / s or less (sec / [Pa s]) using a capillary rheometer equipped with an orifice having a radius of 1 mm and a capillary length of 10 mm attached to the end of a barrel having a furnace body diameter of 0.955 mm. ３ / min, shear rate 122 sec －１Drawdown time: the time required for a resin composition extruded from an orifice to fall 20 cm when measuring the melt viscosity. [Item 8] The resin composition according to any one of Items 1 to 7, wherein the other hydroxyalkanoate units in at least one or all of the copolymers (A), (B), and (C) are 3-hydroxyhexanoate. [Item 9] A film comprising the resin composition according to any one of Items 1 to 8. [Item 10] A laminate comprising a laminate layer comprising the resin composition according to any one of Items 1 to 8 and a substrate layer. [Item 11] The laminate according to Item 10, wherein the substrate layer is biodegradable. [Item 12] The laminate according to Item 10 or 11, wherein the substrate layer is paper. [Item 13] A molded product comprising the laminate according to any one of Items 10 to 12. [Item 14] A method for producing a film, comprising the step of melt-extrusion molding the resin composition according to any one of Items 1 to 8 using a T-die. [Item 15] A method for producing the laminate according to any one of items 10 to 12, comprising the steps of forming the laminate layer on at least one surface of the base layer by extrusion lamination. [Item 16] A method for producing the laminate according to any one of items 10 to 12, comprising the steps of forming the resin composition into a film, and disposing the film on at least one surface of the base layer and forming the laminate layer by any one of dry lamination, non-solvent lamination, or thermal lamination.

[0099] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0100] In the examples, the following raw materials were used. (P3HA-based resin powder) A-1: ​​P3HB3HH having a weight average molecular weight of 360,000 obtained by hydrolyzing poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH) having a 3-hydroxyhexanoate (3HH) composition of 26.3 mol% and a standard polystyrene-equivalent weight average molecular weight of 700,000 measured by GPC, obtained in accordance with the method described in Example 9 of WO 2019 / 142845. Note that the adjustment of the molecular weight by hydrolysis was carried out by placing P3HB3HH in a metal container, placing it in a pressure cooker tester (HAST CHAMBER EHS-221M manufactured by ESPEC Corporation), and treating it at a temperature of 190 ° C. to 200 ° C. for 1 to 2 hours.A-2: P3HB3HH having a weight average molecular weight of 330,000, obtained by hydrolyzing P3HB3HH, which has a 3HH composition of 25.8 mol% and a standard polystyrene-equivalent weight average molecular weight of 680,000 as measured by GPC, obtained in accordance with the method described in Example 9 of WO 2019 / 142845. A'-1: P3HB3HH having a 3HH composition of 25.8 mol% and a standard polystyrene-equivalent weight average molecular weight of 680,000 as measured by GPC, obtained in accordance with the method described in Example 9 of WO 2019 / 142845. B-1: P3HB3HH having a 3HH composition of 2.1 mol% and a standard polystyrene-equivalent weight average molecular weight of 700,000 as measured by GPC, obtained in accordance with the method described in Example 2 of WO 2019 / 142845, obtained by hydrolyzing P3HB3HH having a 3HH composition of 360,000. B-2: P3HB3HH having a weight average molecular weight of 330,000, obtained by hydrolyzing P3HB3HH, which has a 3HH composition of 2.0 mol% and a standard polystyrene-equivalent weight average molecular weight of 680,000 as measured by GPC, obtained in accordance with the method described in Example 2 of WO 2019 / 142845. B-3: P3HB3HH having a 3HH composition of 2.0 mol% and a standard polystyrene-equivalent weight average molecular weight of 680,000 as measured by GPC, obtained in accordance with the method described in Example 2 of WO 2019 / 142845. C-1: P3HB3HH having a weight average molecular weight of 220,000, obtained by hydrolyzing P3HB3HH, which has a 3-hydroxyhexanoate (3HH) composition of 6.0 mol% and a standard polystyrene-equivalent weight average molecular weight of 630,000 as measured by GPC, obtained in accordance with the method described in Example 1 of WO 2019 / 142845. C-2: P3HB3HH obtained in accordance with the method described in Example 1 of WO 2019 / 142845, having a 3-hydroxyhexanoate (3HH) composition of 6.0 mol% and a weight average molecular weight of 630,000 in terms of standard polystyrene measured by GPC. C-3: P3HB3HH obtained in accordance with the method described in Example 1 of WO 2019 / 142845, having a 3-hydroxyhexanoate (3HH) composition of 6.0 mol% and a weight average molecular weight of 420,000 in terms of standard polystyrene measured by GPC.

[0101] (Organic Peroxide) D-1: Perbutyl I (tributylperoxyisopropyl monocarbonate, 1-minute half-life temperature: 158.8°C) manufactured by NOF Corporation

[0102] (Plasticizer) E-1: BIOCIZER manufactured by Riken Vitamin Co., Ltd.

[0103] (Additives) F-1: Pentaerythritol (Mitsubishi Chemical Corporation: Neuraizer P) F-2: Behenic acid amide (Nippon Fine Chemicals Co., Ltd.: BNT-22H)

[0104] The evaluation methods used in the examples and comparative examples are described below. [Melt Viscosity] The melt viscosity (η) was measured using a capillary rheometer manufactured by Shimadzu Corporation, which had a barrel with a diameter of 0.955 mm and an orifice with a radius of 1 mm and a capillary length of 10 mm attached to the end of the barrel. The barrel was set at a temperature of 170°C and a volumetric flow rate of 0.716 cm ３ / min, shear rate 122 sec －１ was measured.

[0105] [Drawdown time] When measuring the melt viscosity, the time required for the molten resin discharged from the orifice to fall 20 cm was measured and defined as the drawdown time (DT). When the accurate drawdown time could not be measured due to the occurrence of melt fracture, it was stated as "measurable."

[0106] [Film Evaluation] (Film Thickness Variation Rate) The film thickness variation rate of the obtained film was measured as follows. At a certain measurement point on the film, the thickness was measured at 6 to 9 points at 5 cm intervals in the TD direction (width direction) using a constant pressure thickness gauge conforming to JIS K 2650, and the average film thickness was calculated as the arithmetic mean, and this average value was used as the MD film thickness at that measurement point. Similarly, the MD film thickness was measured at 20 points at 5 cm intervals along the MD direction. The film thickness variation rate was calculated using the following formula from the median of the measured MD film thickness and the difference between the maximum and minimum MD film thickness values ​​(ΔMax-Min). Film thickness variation rate (%) = (ΔMax-Min of MD film thickness) / (median MD film thickness) × 100

[0107] Based on the calculated value of the film thickness variation rate, the applicability to the laminate layer of the laminate was evaluated according to the following criteria: ◎: Film thickness variation rate is less than 20% (excellent applicability) ○: Film thickness variation rate is 20% or more but less than 25% (applicable) △: Film thickness variation rate is 25% or more but less than 30% (applicable, but may not be suitable depending on the application) ×: Film thickness variation rate is 30% or more (not applicable)

[0108] (Width Neck-in Ratio) The width (length in the TD direction / mm) of a film obtained using a T-die with a die lip width T = 500 mm was measured at 20 points along the MD direction at 5 cm intervals, and the neck-in ratio was calculated from the median value using the following formula: Neck-in ratio (%) = [die width (T) - median width of film] / die width (T) × 100

[0109] Based on the calculated neck-in ratio, the applicability of the laminate to the laminate layer was evaluated according to the following criteria: ◎: Neck-in ratio is 25% or less (excellent applicability) ○: Neck-in ratio is 26% to 35% (applicable) △: Neck-in ratio is 36% to 45% (applicable, but may be unsuitable depending on the application) ×: Neck-in ratio is 46% or more (not applicable)

[0110] [Evaluation of Laminates] (Crack Resistance) If there are fine cracks in the laminate layer of a laminate, the chemical agent will penetrate into the cracks, causing discoloration. Taking advantage of this, the crack resistance of the laminate was evaluated using the following method. The laminate layer of the laminate was bent 90° along the MD direction with the laminate layer facing outward to form a bent section, and Ageless Seal Check (manufactured by Mitsubishi Gas Chemical Company) was applied to the bent section at room temperature (15-25°C). After the chemical agent was applied, the bent section was thoroughly dried and observed under a microscope at 40x magnification. Evaluation was performed using the following criteria based on the degree of discoloration caused by the chemical agent penetrating into the bent section. Similarly, a bent section was formed in the TD direction and evaluated using the same criteria. ◯: Almost no discoloration was observed. △: Slight discoloration was observed. ×: Significant discoloration was observed.

[0111] Example 1 Production of P3HA-Based Resin Pellets P3HA A-2 (24 parts by weight), B-2 (16 parts by weight), organic peroxide D-1 (0.105 parts by weight), plasticizer E-1 (0.42 parts by weight), additive F-1 (1.0 part by weight), and F-2 (0.5 parts by weight) were fed from the main feeder, and C-1 (60 parts by weight) was fed from the side feeder into a co-rotating intermeshing twin-screw extruder (Toshiba Machine Co., Ltd.: TEM26SS (L / D = 60)), and melt-kneaded at a barrel temperature of 140 to 160°C, a screw rotation speed of 100 rpm, and a discharge rate of 10 kg / hr. The P3HA (A-2 and B-2) fed from the main feeder during this process was a reaction product with the organic peroxide. The strand obtained from the die was passed through a water tank filled with warm water at 40 to 45°C to solidify it, and then cut with a pelletizer to obtain P3HA-based resin pellets 1. The obtained pellets were used to evaluate melt viscosity and drawdown, and the results are shown in Table 1. Table 1 also shows the weight-average molecular weight of each P3HA or the entire P3HA-based resin component before reaction with the organic peroxide.

[0112] <Production of Laminate by Thermal Lamination Method> The P3HA resin pellets 1 were charged into a single-screw extruder equipped with a T-die, extruded through the T-die under conditions such that the resin temperature immediately after extrusion was 163 to 167°C, and taken up at a take-up speed (film processing speed) of 22 m / min or 45 m / min using a cooling roll set at 60°C to form a film, thereby obtaining a P3HA film. The films obtained at each processing speed were evaluated for film thickness variation and neck-in ratio, and the results are shown in Table 1.

[0113] Furthermore, the P3HA film obtained above and a basis weight of 210 g / m ２ The base paper was sandwiched between a heating roll on the paper side and a cooling roll on the P3HA film side, and conditions were adjusted so that the surface temperature of the P3HA film reached 170°C, yielding a laminate comprising a paper substrate and a laminate layer. The crack resistance of the resulting laminate was evaluated, and the results are shown in Table 1.

[0114] Examples 2 to 5 P3HA resin pellets 2 to 5, films, and laminates were prepared in the same manner as in Example 1, except that the formulations were changed as shown in Table 1, and the same evaluations were carried out as in Example 1. The results are summarized in Table 1.

[0115] Example 6 P3HA-based resin pellets 6, a film, and a laminate were prepared in the same manner as in Example 1, except that C-1 was fed from the main feeder instead of the side feeder, and the same evaluations as in Example 1 were carried out. The results are summarized in Table 1. Note that the P3HA (A-2, B-2, and C-1) fed from the main feeder during the melt-kneading process was a reaction product with an organic peroxide.

[0116] (Comparative Example 1) P3HA A-2 (24 parts by weight), B-2 (16 parts by weight), plasticizer E-1 (0.42 parts by weight), additive F-1 (1.0 parts by weight), F-2 (0.5 parts by weight) from the main feeder, C-1 (60 parts by weight) from the side feeder co-axial intermeshing twin screw extruder (Toshiba Machine Co., Ltd.: TEM26SS (L / D = 60)) was added, the barrel temperature was 140 to 160 ° C., the screw rotation speed was 100 rpm, and the discharge rate was 10 kg / hr. Melt-kneading was carried out. The strand obtained from the die was solidified by passing it through a water tank filled with hot water at 40 to 45 ° C., and then cut with a pelletizer to obtain P3HA resin pellets 7.

[0117] <Production of Laminate by Thermal Lamination Method> The P3HA resin pellets 7 were fed into a single-screw extruder equipped with a T-die, extruded through the T-die under conditions such that the resin temperature immediately after extrusion was 163 to 167°C, and taken up with a cooling roll set at 60°C at a take-up speed (film processing speed) of 22 m / min or 45 m / min to form a film. At a film processing speed of 22 m / min, a film could be formed, although there was significant variation in film thickness. However, at a film processing speed of 45 m / min, the film thickness variation and neck-in rate during processing were extremely large, making it impossible to continuously obtain a film-shaped molded product.

[0118] P3HA film obtained at a film processing speed of 22 m / min and a basis weight of 210 g / m ２An attempt was made to produce a laminate by sandwiching the base paper with the heating roll on the paper side and the cooling roll on the P3HA film side, but because the thickness of the P3HA film varied greatly, uniform lamination could not be performed and a good laminate could not be obtained.

[0119] (Comparative Example 2) P3HA A'-1 (36 parts by weight), B-3 (24 parts by weight), C-2 (10 parts by weight), C-3 (30 parts by weight), organic peroxide D-1 (0.8 parts by weight), plasticizer E-1 (0.42 parts by weight), additive F-1 (1.0 parts by weight), F-2 (0.5 parts by weight) were fed from the main feeder to a co-rotating intermeshing twin-screw extruder (Toshiba Machine Co., Ltd.: TEM26SS (L / D = 60)), and the barrel temperature was 140 to 160 ° C., the screw rotation speed was 100 rpm, and the melt kneading was carried out at a discharge rate of 10 kg / hr. In this process, P3HA (A'-1, B-3, C-2, C-3) was fed from the main feeder to the reaction product with the organic peroxide. The strand obtained from the die was passed through a water tank filled with warm water at 40 to 45°C to solidify it, and then cut into pellets with a pelletizer to obtain P3HA-based resin pellets 8.

[0120] <Production of Laminate by Thermal Lamination Method> The P3HA resin pellets 8 were charged into a single-screw extruder equipped with a T-die, extruded through the T-die under conditions such that the resin temperature immediately after extrusion was 163 to 167°C, and taken up with a cooling roll set at 60°C at a take-up speed (film processing speed) of 22 m / min or 45 m / min to form a film. In both cases where the film processing speed was 22 m / min or 45 m / min, the film thickness fluctuation and neck-in rate during processing were extremely large, making it impossible to continuously obtain a film-shaped molded product, and it was also impossible to obtain a good laminate.

[0121]

[0122] The following can be seen from Table 1. In Examples 1 to 6, the film thickness fluctuation and neck-in ratio were suppressed, and films and laminates with relatively uniform film thickness and width were obtained. On the other hand, in Comparative Examples 1 and 2, the film thickness fluctuation and neck-in ratio were large, and it was difficult to obtain films or laminates with relatively uniform film thickness and width.

Claims

1. A resin composition for T-die extrusion containing a poly(3-hydroxyalkanoate)-based resin component, The poly(3-hydroxyalkanoate) resin component is A copolymer (A) of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of other hydroxyalkanoate units is 24 mol% or more; A copolymer (B) of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of other hydroxyalkanoate units is 1 mol% or more and less than 5 mol%, and The copolymer (C) contains 3-hydroxybutyrate units and other hydroxyalkanoate units, and the content of the other hydroxyalkanoate units is 5 mol% or more and less than 24 mol%, The copolymer (A) has a weight average molecular weight of 100,000 or more and 500,000 or less, A resin composition for T-die extrusion, wherein at least one or all of the copolymer (A), the copolymer (B), and the copolymer (C) is a reaction product with an organic peroxide.

2. 2. The resin composition for T-die extrusion according to claim 1, wherein the content of the copolymer (A) relative to the total amount of the poly(3-hydroxyalkanoate)-based resin component is 15% by weight or more and 45% by weight or less.

3. The resin composition for T-die extrusion according to claim 1 or 2, wherein at least the copolymer (A) is a reaction product with the organic peroxide.

4. 3. The resin composition for T-die extrusion according to claim 1, wherein the total amount of the organic peroxides used in the resin composition is 0.1 parts by weight or more and 1.0 parts by weight or less per 100 parts by weight of the copolymer (A).

5. The resin composition for T-die extrusion according to claim 1 or 2, wherein the resin composition has a melt viscosity [η] of 300 Pa·s or more and 1000 Pa·s or less. Melt viscosity: Using a capillary rheometer equipped with an orifice having a radius of 1 mm and a capillary length of 10 mm at the end of a barrel having a furnace diameter of 0.955 mm, the barrel was set at a temperature of 170°C and a volumetric flow rate of 0.716 cm ３ / min, shear rate 122 sec －１ Melt viscosity measured at

6. The resin composition for T-die extrusion according to claim 1 or 2, wherein the drawdown time of the resin composition is 14 seconds or more and 45 seconds or less. Drawdown time: The time required for a resin composition discharged from an orifice to fall 20 cm when measuring melt viscosity

7. The resin composition has a ratio (t / η) of the drawdown time [t] to the melt viscosity [η] of 3.4×10 －２ ((sec / [Pa・s]) or more 8.0×10 －２ The resin composition for T-die extrusion according to claim 1 or 2, wherein the viscosity is (sec / [Pa·s]) or less. Melt viscosity: Using a capillary rheometer equipped with an orifice having a radius of 1 mm and a capillary length of 10 mm at the end of a barrel having a furnace diameter of 0.955 mm, the barrel was set at a temperature of 170°C and a volumetric flow rate of 0.716 cm ３ / min, shear rate 122 sec －１ Melt viscosity measured at Drawdown time: the time required for the resin composition discharged from the orifice to fall 20 cm when measuring the melt viscosity

8. The resin composition for T-die extrusion according to claim 1 or 2, wherein the other hydroxyalkanoate units in at least one or all of the copolymers (A), (B), and (C) are 3-hydroxyhexanoate.

9. A T-die extruded film comprising the resin composition for T-die extrusion according to claim 1 or 2.

10. A method for producing a T-die extruded film, comprising a step of melt-extrusion molding the resin composition for T-die extrusion according to claim 1 or 2 using a T-die.

11. A laminate comprising a T-die extrusion laminate layer containing the resin composition for T-die extrusion according to claim 1 or 2, and a substrate layer.

12. The laminate according to claim 11 , wherein the substrate layer is biodegradable.

13. The laminate of claim 11 , wherein the substrate layer is paper.

14. A method for producing the laminate of claim 11, comprising: A method for producing a laminate, comprising the step of forming the T-die extrusion laminate layer on at least one surface of the base material layer by extrusion lamination.

15. A method for producing the laminate of claim 11, comprising: A step of melt-extruding the resin composition into a film using a T-die; and A method for producing a laminate, comprising the steps of placing the film on at least one surface of the base layer and forming the laminate layer by any one of dry lamination, non-solvent lamination, and thermal lamination.

16. A molded article comprising the laminate of claim 11.