Polyhydroxyalkanoic acid film, packaging body, agriculture, forestry and aquaculture material, biological decomposition method, and agriculture, forestry and aquaculture raw material

Abstract

The present invention addresses the problem of providing a polyhydroxyalkanoic acid film which has biodegradability and is capable of reducing the number of pinholes generated after repeated bending. [Solution] A polyhydroxyalkanoic acid film having a puncture strength (equivalent to a thickness of 20 [mu] m) of 80 gf or more.

Description

Technical Field

[0001] The present invention relates to a polyhydroxyalkanoic acid film, a packaging body, an agricultural, forestry and fishery material, a biodegradation method and an agricultural, forestry and fishery raw material. Background Art

[0002] From the perspective of curbing global warming, countries around the world are making various efforts to achieve carbon neutrality. Plastic products, in particular, emit large amounts of CO2 during their manufacture and disposal, leading to demands for reductions in their use and disposal. Packaging plastics are particularly common among various plastic products, and many of these are disposable. Therefore, there is a demand for reductions in the use and disposal of packaging plastics, including films, as well as for recycling and conversion to plant-based materials.

[0003] Furthermore, the environmental pollution caused by plastics entering the ocean has also drawn attention in recent years. For example, there have been reports of fish, seabirds, and marine mammals dying from ingesting plastic products that drift into the ocean. Furthermore, there have been reports of microplastics, broken down by waves and ultraviolet light, bioaccumulating in the marine food chain and impacting fish and other human ingesting organisms. These problems arise from improperly disposed packaging plastics and agricultural plastics entering the ocean through rivers, or from discarded plastics used in fisheries and aquaculture that drift at sea. Therefore, to address the issue of improperly disposed packaging plastics and agricultural, forestry, and fishery plastics, there is a growing demand for biodegradable plastics.

[0004] To combat marine pollution caused by such plastics, there are hopes for the use of biodegradable plastics. However, a 2015 report compiled by the United Nations Environment Programme stated that plastics such as polylactic acid, which biodegrade in compost, cannot be expected to decompose quickly in the cold ocean, making them a poor solution to marine pollution. Among biodegradable plastics, aliphatic polyester resins are particularly attractive due to their high biodegradability, and films made from polyhydroxyalkanoic acid resins are being studied for their use in packaging materials.

[0005] As biodegradable films, sheets for preserving fruit and vegetable packaging, manufactured by the inflation method from resins such as polylactic acid, polybutylene succinate, polybutylene adipate terephthalate, 3-hydroxybutyrate-co-3-hydroxyhexanoate copolymer, and polyhydroxyalkanoic acid, have been proposed (Patent Document 1). Furthermore, a method for producing biodegradable films has been proposed in which a polyhydroxyalkanoic acid resin sheet is subjected to a primary stretching process in a temperature range between -25°C and below the sheet's melting point to partially melt-stretch the sheet, followed by a secondary stretching process (Patent Document 2). Furthermore, a method for producing polyhydroxyalkanoic acid films has been proposed in which a sheet mixed with a poly(3-hydroxybutyrate) resin is subjected to continuous biaxial stretching in both the machine direction (MD) and the orthogonal direction (TD) at a stretch ratio of 1.1 or greater during the film production process, without rolling (Patent Document 3).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2022-106249

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2003-311825

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2022-62759 Summary of the Invention

[0011] Inventions must solve problems

[0012] However, since Patent Document 1 is manufactured by a blow molding process, the molecular chains of the polyhydroxyalkanoic acid resin are insufficiently stretched, leaving room for improvement in further strength enhancement. In particular, the film of Patent Document 1 develops a significant number of pinholes after repeated bending, making it difficult to use for applications requiring high content protection. Furthermore, the films described in Patent Document 2 all achieve strength enhancement through secondary stretching, but since this involves multi-stage stretching in a uniaxial direction, the strength enhancement is limited to one direction, leaving room for improvement in the strength in directions orthogonal to the stretching direction. Furthermore, repeated bending in multiple directions produces a significant number of pinholes. The film described in Patent Document 3 utilizes a biaxial stretching method for a polyhydroxyalkanoic acid film, but the areal stretching ratio during film production is low, resulting in insufficient molecular chain stretching of the polyhydroxyalkanoic acid resin, leaving room for improvement in further strength enhancement.

[0013] Therefore, an object of the present invention is to provide a polyhydroxyalkanoic acid film that is biodegradable and can reduce the number of pinholes generated after repeated bending.

[0014] Means of solving problems

[0015] The present inventors have conducted intensive research to solve the above-mentioned problems and have finally completed the present invention described below.

[0016] [1] A polyhydroxyalkanoic acid film having a puncture strength of 80 gf or more as determined by the following measuring apparatus and measuring conditions, wherein the puncture strength is a value converted to a thickness of 20 μm. Measuring device: KATOTECH's small compression tester, HANDY-TYPE COMPRESSIONTESTER KES-G5 Measurement conditions: Sensitivity (SENS): 10 Speed: 0.20 cm / s Stroke: 20mm / 10V Needle diameter: 1.0mm

[0017] Aperture: 10.0mm .

[0018] [2] For the polyhydroxyalkanoic acid film described in [1], when the breaking strength in the direction of the main orientation axis is denoted as S1 and the breaking strength in the direction perpendicular to the main orientation axis is denoted as S2, S1 and S2 satisfy equations (1) and (2), wherein the units of S1 and S2 are both MPa, 30MPa≤S1≤280MPa Formula (1) 30MPa≤S2≤280MPa Formula (2).

[0019] [3] The polyhydroxyalkanoic acid film as described in [1] or [2], in which, in the thermal shrinkage curve obtained by a thermomechanical analyzer (TMA), the shrinkage start temperature T1 in the direction of the main orientation axis of the film and the shrinkage start temperature T2 in the direction orthogonal to the main orientation axis are both 40°C or higher and 150°C or lower, wherein the units of T1 and T2 are both °C.

[0020] [4] The polyhydroxyalkanoic acid film as described in any one of [1] to [3], wherein the refractive index at a wavelength of 1550 nm in the direction of the main orientation axis is denoted as N1 and the refractive index at a wavelength of 1550 nm in a direction perpendicular to the main orientation axis is denoted as N2, N1 and N2 satisfy the formula (3), 2.0×10 -4 ≤ㅣN1-N2ㅣ≤1.3×10 -2 Formula (3).

[0021] [5] The polyhydroxyalkanoic acid film as described in any one of [1] to [4], wherein the thermal shrinkage H1 in the main orientation axis direction of the film and the thermal shrinkage H2 in the direction perpendicular to the main orientation axis direction, obtained by heat treatment at 120°C for 15 minutes, are both greater than 0% and less than 20%, wherein the units of H1 and H2 are both %.

[0022] [6] For the polyhydroxyalkanoic acid film as described in any one of [1] to [5], when the elongation at break in the main orientation axis direction is denoted as L1 and the elongation at break in the direction perpendicular to the main orientation axis direction is denoted as L2, both L1 and L2 are greater than 10% and less than 350%, wherein the units of L1 and L2 are both %.

[0023] [7] The polyhydroxyalkanoic acid film according to any one of [1] to [6], wherein the puncture displacement determined by the following measuring apparatus and measuring conditions is 2.0 mm or more and 4.5 mm or less, Measuring device: KATOTECH's small compression tester, HANDY-TYPE COMPRESSIONTESTER KES-G5 Measurement conditions: Sensitivity (SENS): 10 Speed: 0.20 cm / s Stroke: 20mm / 10V Needle diameter: 1.0mm

[0024] Aperture: 10.0mm .

[0025] [8] The polyhydroxyalkanoic acid film according to any one of [1] to [7] satisfies formula (4) when the refractive index at a wavelength of 1550 nm in the direction of the main orientation axis is denoted as N1, the refractive index at a wavelength of 1550 nm in a direction perpendicular to the main orientation axis is denoted as N2, the refractive index at a wavelength of 1550 nm in the thickness direction is denoted as Nz, and the average value of N1 and N2 is denoted as N12. 0.002≤(N12 - Nz)≤0.015 Formula (4).

[0026] [9] In the polyhydroxyalkanoic acid film as described in any one of [1] to [8], when the peak with the highest intensity among the peaks with an orientation degree of 0.50 or more in the range of a diffraction angle 2θ of 19° or more and 21° or less is recorded as PB, the crystallite size determined from the half-peak width of PB is 5 nm or more and 60 nm or less in wide-angle X-ray diffraction in the thickness direction using CuKα rays.

[0027]

[10] The polyhydroxyalkanoic acid film as described in any one of [1] to [9], further comprising a functional layer on at least one side.

[0028]

[11] The polyhydroxyalkanoic acid film as described in any one of [1] to

[10] is used for packaging purposes.

[0029]

[12] . A packaging body comprising the polyhydroxyalkanoic acid film described in any one of [1] to

[11] .

[0030]

[13] The polyhydroxyalkanoic acid membrane as described in any one of [1] to

[11] is used in agriculture, forestry and fishery.

[0031]

[14] . An agricultural, forestry, and fishery material comprising the polyhydroxyalkanoic acid membrane described in any one of [1] to

[11] .

[0032]

[15] A biodegradation method for decomposing the polyhydroxyalkanoic acid film described in any one of [1] to

[11] using composting equipment.

[0033]

[16] A biodegradation method for decomposing the packaging body described in

[12] using composting equipment.

[0034]

[17] . A biodegradation method for decomposing the agricultural, forestry and aquaculture materials described in

[14] . using composting equipment.

[0035]

[18] . The polyhydroxyalkanoic acid film as described in any one of [1] to

[11] is a film for coating agricultural, forestry and fishery raw materials, wherein the agricultural, forestry and fishery raw materials contain one or more selected from fertilizers, feeds, seedlings and chemicals.

[0036]

[19] . A raw material for agriculture, forestry and fishery, characterized in that it is coated with the polyhydroxyalkanoic acid film described in any one of [1] to

[11] .

[0037] Effects of the Invention

[0038] The polyhydroxyalkanoic acid film obtained by the present invention is biodegradable and can reduce the number of pinholes generated after repeated bending. As a result, it can fully protect the contents and is therefore suitable for packaging and agricultural, forestry and fishery applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is an oblique plan view schematically showing the positional relationship among an X-ray source, a sample, and a diffraction image in wide-angle X-ray diffraction measurement.

[0040] Figure 2 It is from Figure 1 The diagram when viewed from the AB direction.

[0041] Figure 3 It is from Figure 1 The diagram when viewed from the BC direction. DETAILED DESCRIPTION

[0042] The polyhydroxyalkanoic acid film of the present invention is described in detail below. When the upper limit and lower limit of the preferred range are described below, the combination of the upper limit and lower limit can be arbitrary. In addition, in this specification, the polyhydroxyalkanoic acid film is sometimes referred to as a film. In addition, in the polyhydroxyalkanoic acid film of the present invention, the "thickness direction" refers to the direction perpendicular to the film surface. The "length direction" is the direction corresponding to the flow direction in the film manufacturing process (hereinafter sometimes referred to as "MD"), and the "width direction" is the direction perpendicular to the flow direction in the above-mentioned film manufacturing process within the film surface (hereinafter sometimes referred to as "TD"). When the film sample is in the shape of a reel, a roller, etc., it can be said that the film winding direction is the length direction. When the stretching direction (length direction and width direction) is unknown, the breaking strength of the fracture is measured in the tensile test described later, and the direction with the larger measured value is taken as the main orientation axis direction. Specifically, the main orientation axis direction is determined by the following method. Specifically, prepare a film, face any direction upward, and cut out a rectangular sample with a length of 150 mm and a width of 10 mm. <1> , the sample <1> The direction of the long side is defined as 0°. Next, collect samples of the same size with the long side direction rotated 15° to the right from the 0° direction. <2> In the same way, the long side of the rectangular sample is rotated 15 degrees at a time and the sample is collected in the same way. <3> ~ <12> . Next, each rectangular sample is placed on a tensile testing machine (for example, "TENSILON Universal Testing Machine" RTG-1210 manufactured by A&D) with the long side direction as the tensile direction so that the initial distance between the chucks is 30 mm, and a tensile test is performed at a tensile speed of 300 mm / min in an atmosphere of temperature and humidity of 25±5°C and 65±10% RH. At this time, the maximum load until the sample breaks is read, and the value obtained by dividing the maximum load by the cross-sectional area of ​​the sample before the test (film thickness × width) is calculated as the breaking strength, and the long side direction of the sample with the largest value is taken as the main orientation axis direction of the polyhydroxyalkanoic acid film. In addition, the direction perpendicular to the main orientation axis direction within the film surface is taken as the direction perpendicular to the main orientation axis direction of the polyhydroxyalkanoic acid film.

[0043] The polyhydroxyalkanoic acid film of the present invention preferably has a puncture strength (value converted to a thickness of 20 μm) of 80 gf or greater. A puncture strength (value converted to a thickness of 20 μm) of 80 gf or greater provides strength suitable for processing, resulting in sufficiently high puncture resistance and excellent pinhole resistance. This improves the shelf life and barrier properties of the contents when used in packaging or agricultural, forestry, and fishery applications, for example. Furthermore, a puncture strength (value converted to a thickness of 20 μm) of 1500 gf or less is preferred. This provides flexibility suitable for processing, balancing drillability with excellent pinhole resistance. This facilitates punching processes such as those for hand-tearability when used in packaging or agricultural, forestry, and fishery applications, for example. Based on this perspective, the puncture strength (value converted to a thickness of 20 μm) is more preferably 150 gf or greater, further preferably 200 gf or greater, and particularly preferably 250 gf or greater. Furthermore, from this perspective, the puncture strength (value calculated based on a thickness of 20 μm) is more preferably 1500 gf or less, further preferably 1000 gf or less, even more preferably 900 gf or less, particularly preferably 850 gf or less, and most preferably 800 gf or less. The puncture strength (value calculated based on a thickness of 20 μm) is measured using the method described in the Examples.

[0044] There is no particular limitation on the method for controlling the puncture strength within the above range. Examples include, for example, the use of a polyhydroxyalkanoic acid resin containing a specific crystal nucleating agent, adjusting the film transport speed at the longitudinal stretching entrance relative to the speed at the casting drum outlet during film formation, and performing biaxial stretching. More specifically, by using a polyhydroxyalkanoic acid resin containing one or more selected from fatty acid amides, urea derivatives, sorbitol-based compounds, boron nitride, fatty acid salts, and aromatic fatty acid salts as a crystal nucleating agent, it is possible to form more fine crystals with small crystallite sizes in the film. Subsequently, by controlling the film transport speed at the casting drum outlet and the longitudinal stretching entrance, it is possible to improve the orderliness of the molecular chain arrangement after longitudinal stretching, thereby imparting appropriate flexibility and strength. Furthermore, the higher the stretching ratio, the higher the constraint force between adjacent molecular chains due to entanglement, and further, by performing thermal crystallization by heat treatment after stretching, a synergistic effect can be exerted, the puncture strength can be improved, and a film with excellent pinhole resistance can be obtained. More specifically, this can be achieved by making the relative value of the film conveying speed at the longitudinal stretching inlet to the speed at the casting drum outlet be greater than 101% and less than 125% during film formation, and performing biaxial stretching by a sequential biaxial method to an area ratio of more than 4 times, and controlling the heat treatment temperature after biaxial stretching to be greater than 70°C and less than 150°C.

[0045] In the polyhydroxyalkanoic acid film of the present invention, when the breaking strength in the main orientation axis direction is represented by S1 (MPa) and the breaking strength in the direction perpendicular to the main orientation axis direction is represented by S2 (MPa), S1 and S2 preferably satisfy equations (1) and (2).

[0046] 30MPa≤S1≤280MPa Formula (1)

[0047] 30MPa≤S2≤280MPa Formula (2)

[0048] By setting S1 and S2 to be 30 MPa or higher, the mechanical strength of the polyhydroxyalkanoic acid film becomes sufficiently high, particularly when applying various functional layers for packaging and agricultural, forestry, and aquatic products applications, it is possible to suppress relaxation during vapor deposition and transportation, thereby preventing film breakage caused by tension. Furthermore, S1 and S2 are preferably both 280 MPa or lower. To achieve a mechanical strength exceeding 280 MPa, it is necessary to increase the stretch ratio or lower the stretching temperature during film formation to improve orientation. Therefore, from the perspective of suppressing breakage and improving productivity, S1 and S2 are both more preferably 240 MPa or lower, and more preferably 200 MPa or lower. On the other hand, from the perspective of suppressing deformation caused by tension during roll-to-roll vapor deposition or transportation, S1 and S2 are both more preferably 35 MPa or higher, and more preferably 40 MPa or higher. The breaking strength is measured using the method described in the Examples. There is no particular limitation on the method for controlling S1 and S2 within the above ranges; for example, the same method as that used to control the puncture strength is preferably used.

[0049] In the thermal shrinkage curve of the polyhydroxyalkanoic acid film of the present invention, measured using a thermomechanical analyzer (TMA), the shrinkage onset temperature T1 (°C) in the direction of the film's principal orientation axis and the shrinkage onset temperature T2 (°C) in a direction perpendicular to the principal orientation axis are preferably both 40°C to 150°C. Polyhydroxyalkanoic acid films are generally known to have a glass transition temperature near 0°C, and biaxially stretched polyhydroxyalkanoic acid films sometimes begin to shrink near the glass transition temperature of 0°C. Therefore, by setting both T1 and T2 of the polyhydroxyalkanoic acid film of the present invention to 40°C to 150°C, the dimensional stability of the polyhydroxyalkanoic acid film is sufficiently high. In particular, during vapor deposition, the polyhydroxyalkanoic acid film does not expand due to the heat generated during deposition and deforms appropriately toward the shrinking direction, avoiding excessive shrinkage. This prevents defects such as pinholes and cracks in the D layer (described later), and allows for excellent barrier properties in a laminate incorporating the D layer. In addition, in order to make T1 and T2 exceed 150°C, it is necessary to perform heat treatment at a temperature exceeding 150°C during film formation, which may cause film cracking during film formation. From the perspective of poor productivity, T1 and T2 are preferably below 150°C. From the above viewpoint, T1 and T2 are more preferably above 44°C, further preferably above 49°C, and particularly preferably above 55°C. From the above viewpoint, T1 and T2 are more preferably below 144°C, further preferably below 139°C, further preferably below 130°C, and particularly preferably below 119°C. In addition, each shrinkage start temperature is measured using the method described in the examples. There is no particular limitation on the method for controlling T1 and T2 within the above ranges. For example, the following method as described later can be cited: using a polyhydroxyalkanoic acid resin containing a specific crystal nucleating agent, adjusting the relative value of the film conveying speed at the longitudinal stretching inlet relative to the speed at the casting drum outlet during film formation, and performing heat treatment after biaxial stretching. In particular, the use of a polyhydroxyalkanoic acid resin containing a crystallization nucleating agent can produce a large number of fine crystals with small crystallite sizes in the film. Subsequently, by controlling the film feed speed at the casting drum outlet and the longitudinal stretching inlet, the orderliness of the molecular chain arrangement after longitudinal stretching can be improved. Furthermore, the higher the stretching ratio, the greater the constraint between adjacent molecular chains due to entanglement. Furthermore, thermal crystallization through post-stretching heat treatment can exert a synergistic effect, increasing the shrinkage onset temperature. More specifically, this can be achieved by setting the film feed speed at the longitudinal stretching inlet relative to the speed at the casting drum outlet to 101% or more and 125% or less during film formation, biaxially stretching to an area ratio of 4 or more using a sequential biaxial method, and controlling the heat treatment temperature after biaxial stretching to 70°C or more and 150°C or less.

[0050] In the polyhydroxyalkanoic acid film of the present invention, when N1 is the refractive index at a wavelength of 1550 nm in the main orientation axis direction and N2 is the refractive index at a wavelength of 1550 nm in a direction perpendicular to the main orientation axis direction, N1 and N2 preferably satisfy formula (3).

[0051] 2.0×10 -4 ≤ㅣN1-N2ㅣ≤1.3×10 -2 Formula (3)

[0052] |N1-N2| is 2.0×10 -4 The above indicates that the molecular chains in the plane of the polyhydroxyalkanoic acid film form a crystalline structure in a state of maximum elongation rather than a helical structure, and it is believed that the molecular chain orientation anisotropy is given, and the ester groups of the molecular chains are easily exposed, so that excellent biodegradability can be exhibited. In addition, the molecular chain orientation becomes higher in the plane direction of the film, the interaction between the molecular chains is enhanced, and the mechanical strength can be improved. As described above, by giving the molecular chain orientation anisotropy in the plane, for example, relaxation during vapor deposition processing or relaxation during transportation that may occur when used for packaging purposes or agricultural, forestry and fishery purposes can be suppressed, and film rupture caused by tension can be suppressed. In addition, when the anisotropy of the molecular chain orientation in the main orientation axis direction of the film and the direction orthogonal to the main orientation axis direction is too high, in addition to the stress during film transportation in the post-processing step causing damage to the film, when used as a packaging material or agricultural, forestry and fishery material, it sometimes becomes the starting point of partial damage such as cracks caused by protrusions of the inner package. Therefore, it is preferred to make |N1-N2| 1.3×10 -2 From the above viewpoint, |N1-N2| is more preferably 4.0×10 -4 More preferably, 6.0×10 -4 More than 1.0×10 -3 From the above viewpoint, it is more preferably 1.1×10 -2 Below, more preferably 1.0×10 -2 Below, particularly preferably 9.0×10 -3 The method for controlling |N1-N2| to fall within the above range is not particularly limited, and examples thereof include adjusting the film feed speed at the longitudinal stretching inlet relative to the speed at the casting drum outlet during film formation and performing biaxial stretching. More specifically, during film formation, the film feed speed at the longitudinal stretching inlet relative to the speed at the casting drum outlet is set to 101% or more and 125% or less, and biaxial stretching is performed using a sequential biaxial method at an area ratio of 4 or more. The refractive indices are determined by the methods described in the Examples.

[0053] The polyhydroxyalkanoic acid film of the present invention preferably has a heat shrinkage H1 (%) in the direction of the film's main orientation axis and a heat shrinkage H2 (%) in a direction perpendicular to the main orientation axis, both of which are 0% or more and 20% or less, as determined by heat treatment at 120°C for 15 minutes. This is preferred from the perspective of achieving sufficiently high dimensional stability in both the main orientation axis and the direction perpendicular to the main orientation axis, and suppressing wrinkling and sagging during high-speed processing. From this perspective, both H1 and H2 are more preferably 15% or less, further preferably 9% or less, and particularly preferably 6% or less. While there are no particular lower limits for H1 and H2, from the perspective of preventing wrinkling or sagging during high-speed processing due to thermal expansion, both H1 and H2 are more preferably 0.1% or more, and further preferably 0.3% or more. In this specification, heat shrinkage can be determined as the change (%) in film length before and after heat treatment at 120°C for 15 minutes in a specified direction. Specifically, it is measured using the method described in the Examples. There are no particular limitations on the method for controlling H1 and H2 within the above-mentioned ranges. Examples include the use of a polyhydroxyalkanoic acid resin containing a specific nucleating agent, controlling the film transport speed at the casting drum outlet and the longitudinal stretching inlet during film formation, adjusting the stretch ratio, and adjusting the conditions for the post-stretching heat treatment and relaxation treatment. In particular, by using a polyhydroxyalkanoic acid resin containing a crystallizing nucleating agent, a large number of fine crystals with small crystallite sizes can be formed in the film. Furthermore, by controlling the film transport speed at the casting drum outlet and the longitudinal stretching inlet, the orderliness of the molecular chain arrangement after longitudinal stretching can be improved. Furthermore, by performing a post-stretching heat treatment within the preferred time range described below, thermal crystallization can be achieved. By performing a relaxation treatment within the preferred speed range described below, excess tension in the molecular chains can be relaxed, thereby reducing thermal shrinkage.

[0054] In the polyhydroxyalkanoic acid film of the present invention, when the elongation at break in the direction of the principal orientation axis is represented by L1 (%) and the elongation at break in the direction perpendicular to the principal orientation axis is represented by L2 (%), both L1 and L2 are preferably 10% or greater and 350% or less. By setting both L1 and L2 to 10% or greater, appropriate flexibility can be imparted, preventing the polyhydroxyalkanoic acid film from becoming extremely deformed and making it less susceptible to breakage due to tension during vapor deposition or transportation. Furthermore, by setting both L1 and L2 to 350% or less, for example, in a structure where the D layer (described later) is laminated, cracking of the D layer during transportation or bag making can be reduced, thereby reducing the risk of impaired barrier properties. From this perspective, both L1 and L2 are more preferably 50% or greater, and even more preferably 90% or greater. Furthermore, from this perspective, both L1 and L2 are more preferably 330% or less, and even more preferably 310% or less. Elongation at break is measured using the method described in the Examples. The method for controlling L1 and L2 to fall within the above ranges is not particularly limited. For example, during film formation, the relative value of the film feed speed at the longitudinal stretching inlet relative to the speed at the casting drum outlet is adjusted, and biaxial stretching is performed. More specifically, during film formation, the film feed speed at the longitudinal stretching inlet relative to the speed at the casting drum outlet is set to 101% or more and 125% or less, and biaxial stretching is performed to an area ratio of 4 or more using a sequential biaxial method.

[0055] The polyhydroxyalkanoic acid film of the present invention preferably has a puncture displacement of 2.0 mm or more and 4.5 mm or less. By making the puncture displacement 2.0 mm or more, the flexibility of the polyhydroxyalkanoic acid film becomes sufficiently high, which can suppress the relaxation during the vapor deposition process and the relaxation during transportation, and suppress the tension from causing the film to rupture. In addition, by making the puncture displacement 4.5 mm or less, it is possible to prevent the polyhydroxyalkanoic acid film from becoming difficult to deform extremely. For example, in the structure of the D layer described later in the stacking, it is possible to reduce the situation where the D layer cracks during transportation or bag making and damages the water vapor barrier or oxygen barrier properties. From the above viewpoint, the puncture displacement is more preferably 2.2 mm or more, more preferably 2.5 mm or more, particularly preferably 3.0 mm or more, and the puncture displacement is more preferably 4.0 mm or less, more preferably 3.5 mm or less. In addition, the puncture displacement is measured using the method described in the examples. There is no particular limitation on the method for controlling the puncture displacement within the above range. For example, the same method as the method for controlling L1 and L2 can be preferably cited.

[0056] The polyhydroxyalkanoic acid film of the present invention preferably satisfies the formula (4) when the refractive index at a wavelength of 1550 nm in the thickness direction is represented by Nz and the average value of the above N1 and N2 is represented by N12.

[0057] 0.002≤(N12-Nz)≤0.015 Formula (4)

[0058] (N12-Nz) indicates that the degree of orientation in the in-plane direction relative to the thickness direction of the polyhydroxyalkanoic acid film is sufficiently high. A (N12-Nz) of 0.002 or greater indicates that the molecular chains within the film plane form a crystalline structure that is as elongated as possible, rather than a helical structure. Consequently, the ester groups of the molecular chains are easily exposed, resulting in excellent biodegradability. Furthermore, by increasing the degree of molecular chain orientation in the in-plane direction of the film, the interaction between the molecular chains is enhanced, which can improve puncture strength. As described above, by increasing the degree of in-plane molecular chain orientation, it is possible to suppress relaxation during vapor deposition processing and transportation when applying various functional layers for use in packaging or agricultural, forestry, and fishery applications, thereby preventing film rupture due to tension. Furthermore, if the film's in-plane orientation is too high, stress during film transport during post-processing can damage the film. This can also lead to partial damage such as cracking caused by protrusions from inclusions when used as packaging materials or agricultural, forestry, and fishery materials. Furthermore, the film may need to have a high areal stretch ratio during film production, which can lead to cracking and poor productivity. Therefore, (N12-Nz) is preferably 0.015 or less. From this perspective, (N12-Nz) is more preferably 0.003 or greater, and even more preferably 0.004 or greater. Furthermore, from this perspective, (N12-Nz) is more preferably 0.010 or less, even more preferably 0.009 or less, and particularly preferably 0.008 or less. There are no particular limitations on the method for controlling (N12-Nz) to fall within the above range; for example, the same methods as those described above for controlling L1 and L2 can be used.

[0059] The polyhydroxyalkanoic acid film of the present invention, in wide-angle X-ray diffraction in the thickness direction using CuKα radiation, has a crystallite size of preferably 5 nm to 60 nm, when the peak with the highest intensity among the peaks with an orientation degree of 0.50 or more in the diffraction angle 2θ range of 19° to 21° is designated as PB. These diffraction peaks originate from the crystal structure of the polyhydroxyalkanoic acid, which contributes to the puncture strength, flexibility, and biodegradability of the film. When the orientation degree is 0.50 or more, the film contains crystal structures with excellent biodegradability. Simultaneously, these crystal structures have high orientation in the planar direction, making them less likely to become the starting point of fracture during impact, thereby improving the film's flexibility. By setting the crystallite size of crystals with such an orientation degree to 5 nm or more, a crystal structure with excellent biodegradability and sufficient orientation can be formed in the film, further improving the biodegradability of the polyhydroxyalkanoic acid film. Furthermore, the film can be prevented from slackening during vapor deposition processing and transportation, which can occur when the film is used for packaging or agricultural, forestry, and fishery applications, thereby suppressing film rupture caused by tension. In addition, by making the above-mentioned crystallite size less than 60nm, the above-mentioned crystal structure can be made to exist without excessive growth during the manufacturing process, and the strength of the polyhydroxyalkanoic acid film can be prevented from decreasing. In addition, when the present film is used as, for example, packaging purposes or agricultural, forestry and aquatic products purposes, it is possible to prevent the film from extreme deformation, and it is possible to reduce the degradation of characteristics caused by cracks or cleavage of the functional layer due to vapor deposition, etc. In addition, it is also possible to make biodegradability good. From the above viewpoint, the above-mentioned crystallite size is more preferably more than 7nm, further preferably more than 9nm, and particularly preferably more than 11nm. In addition, from the above viewpoint, the above-mentioned crystallite size is more preferably less than 50nm, further preferably less than 40nm, further preferably less than 30nm, particularly preferably less than 25nm, and most preferably less than 20nm. In addition, the determination of wide-angle X-ray diffraction in the thickness direction using CuKα lines is carried out using the method described in the examples. The method for controlling the crystallite size within the above-mentioned range is not particularly limited. Examples include, for example, controlling the degree of crystal orientation using the above-mentioned method and then adjusting the stretch ratio during the stretching step during film formation, as well as the heat treatment temperature during the heat treatment and relaxation steps, as described below. More specifically, by setting the longitudinal stretch ratio to 1.5-4.2 times, the transverse stretch ratio to 1.5-4.2 times, or the area ratio to 4-18 times, the crystallite size generated during the preheating period can be controlled within the preferred range through physical tensile stress. Furthermore, by heat treating the polyhydroxyalkanoic acid resin at a temperature between (melting point (°C) - 100°C) and (melting point (°C) - 10°C) after biaxial stretching, crystal growth can be controlled. Stretching ratios below the above-mentioned range may result in coarse crystals remaining after film formation, while stretching ratios above the above-mentioned range may result in excessively small crystal sizes.When the heat treatment temperature is lower than the upper range, the crystal growth may be insufficient, while when it is higher than the above range, only coarse crystals may remain.

[0060] In addition, from the viewpoint of preventing excessive orientation of crystals from causing a decrease in strength, the above-mentioned orientation degree is more preferably 0.99 or less. From the above-mentioned viewpoint, the orientation degree is more preferably 0.75 or more, further preferably 0.90 or more, and particularly preferably 0.95 or more. In addition, from the above-mentioned viewpoint, the above-mentioned orientation degree is more preferably 0.98 or less, and particularly preferably 0.97 or less. In addition, from the viewpoint of appropriately measuring a film having a high orientation degree in a planar direction, it is preferred that when the crystal orientation degree is obtained by the method described in the embodiment, the peak position with the highest intensity in the orientation profile curve (hereinafter sometimes referred to as the orientation angle) appears within a circumferential angle of 90°±10°. There is no particular limitation on the method for controlling the orientation degree within the above-mentioned range, and examples include a method of pre-orienting the crystals generated by adjusting the conveying speed in the interval between the casting drum process and the longitudinal stretching process during film formation, and then performing biaxial stretching.

[0061] The weight average molecular weight Mw of the polyhydroxyalkanoic acid film of the present invention is not particularly limited, but is preferably 5.0×10 4 ~2.0×10 6 , more preferably 1.0×10 5 ~1.50×10 6 , and most preferably 2.5×10 5 ~1.0×10 6 .

[0062] The polyhydroxyalkanoic acid film of the present invention has a polyhydroxyalkanoic acid resin content of more than 50% by mass and less than 100% by mass, based on 100% by mass of the total mass of the film, from the viewpoint of achieving good compostability at room temperature or biodegradability in the ocean. Here, the polyhydroxyalkanoic acid resin is a polymer containing a hydroxyalkanoic acid as a constituent component, and examples thereof include a 3-hydroxyalkanoate repeating unit represented by the general formula [-CHR-CH2-CO-O-] (wherein R is C n H 2n+1 denoted by an alkyl group, where n is an integer of 1 to 15) (also referred to as P3HA), etc. The hydroxyalkanoic acid constituting the hydroxyalkanoic acid resin may be a homopolymer of a single type or a copolymer of two or more types. Furthermore, the polyhydroxyalkanoic acid resin of the present invention may be a mixture of multiple hydroxyalkanoic acid resins.

[0063] Examples of P3HA include poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxyvalerate) (P3HV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P3HB3HV3HH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) (P3HB3HO), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate) (P3HBP3HD). In addition, -co- indicates copolymerization.

[0064] P3HA can be chemically synthesized (e.g., obtained by ring-opening polymerization of the corresponding lactone) or produced by microorganisms. However, P3HA produced by microorganisms is preferred due to its ease of production using biomass raw materials such as vegetable oils. Among P3HA produced by microorganisms, P3HB, P3HV, P3HB3HH, P3HB3HV, P3HB3HV3HH, and P3HB4HB are preferably used due to their ease of industrial production.

[0065] Polyhydroxyalkanoic acid resins, such as P3HA, can adjust their melting point and crystallinity by varying the composition ratio of their repeating units. While polyhydroxyalkanoic acid resins are generally known to be susceptible to thermal decomposition, by forming copolymers of two or more hydroxyalkanoic acids, the melting point is designed to be low, enabling extrusion processing temperatures to be lowered.

[0066] The weight average molecular weight Mw of the polyhydroxyalkanoic acid resin used in the polyhydroxyalkanoic acid film of the present invention is not particularly limited, but is preferably 1.0×10 5 ~2.0×10 6 , more preferably 3.0×10 5 ~1.5×10 6 , the most preferred is 4.0×10 5 ~1.0×10 6 .

[0067] The polyhydroxyalkanoic acid film of the present invention preferably contains a crystal nucleating agent to improve the film's puncture strength and control crystallite size. A crystal nucleating agent is a nucleating agent that enhances the film's crystallinity. Examples of such agents include fatty acid amides, urea derivatives, sorbitol compounds, boron nitride, fatty acid salts, and aromatic fatty acid salts. In the present invention, polyols such as pentaerythritol, galactitol, and mannitol, or orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, and boron nitride are preferred. Pentaerythritol is particularly preferred because it promotes crystallization of the poly(3-hydroxyalkanoate) resin component. The crystal nucleating agent content is preferably 0.1% to 5% by mass based on the total mass of the polyhydroxyalkanoic acid film (100% by mass). To improve the film's puncture strength and facilitate crystallite size control, the crystal nucleating agent content is more preferably 0.3% by mass or greater, and even more preferably 0.5% by mass or greater. On the other hand, from the viewpoint of saturation of the effect as a nucleating agent or cost impact due to excessive addition, the content of the crystal nucleating agent is preferably 5% by mass or less, more preferably 3% by mass or less.

[0068] The polyhydroxyalkanoic acid film of the present invention may contain various additives such as organic particles, inorganic particles, antioxidants, heat stabilizers, lubricants, antistatic agents, antiblocking agents, fillers, viscosity modifiers, and anti-coloring agents within a range that does not impair the purpose of the present invention.

[0069] The polyhydroxyalkanoic acid film of the present invention can be widely used in various applications, such as packaging, mold release, packaging materials, packaging materials, sanitary products, agricultural, forestry and fishery products, construction products, medical products, and engineering films for the manufacture of various products. For example, when used for packaging, it does not break or deform even under the conveying tension in the processing and vapor deposition steps, and can be used as a polyhydroxyalkanoic acid film with excellent barrier properties. Because it is biodegradable, it is also suitable as a polyhydroxyalkanoic acid film for agriculture, forestry and fishery.

[0070] The thickness of the polyhydroxyalkanoic acid film of the present invention can be set accordingly depending on the intended use. For example, for general packaging, demolding, agriculture, forestry, and fishery applications in sheet form, the thickness is preferably 6 μm or more and 200 μm or less. From the perspective of handleability during processing or use, the thickness is more preferably 100 μm or less, more preferably 50 μm or less. The thickness is more preferably 8 μm or more, and even more preferably 10 μm or more. Furthermore, among various applications, for applications involving forming steps such as tray molding and applications requiring self-supporting properties, the thickness is preferably 10 μm or more and 300 μm or less from the perspective of processability and handleability. From the perspectives of cost, film forming properties, and biodegradability, the thickness is more preferably 250 μm or less, more preferably 220 μm or less. Furthermore, the thickness is more preferably 30 μm or more, and even more preferably 50 μm or more.

[0071] <Polyhydroxyalkanoic acid film with functional layer>

[0072] The polyhydroxyalkanoic acid film of the present invention is preferably provided with a corresponding functional layer according to the purpose, and the polyhydroxyalkanoic acid film with a functional layer is described below. In addition, the polyhydroxyalkanoic acid film of the present invention in which a functional layer is provided is sometimes referred to as a "laminate". As the functional layer that can be laminated on the polyhydroxyalkanoic acid film, a gas barrier layer, an adhesive layer, a heat-sealing layer, an easy-adhesive layer, a coloring layer, a printing layer, an easy-peeling layer, a release layer, an easy-slip layer, a porous layer, a non-woven fabric, etc. can be listed. The lamination method of the functional layer can be selected accordingly according to the functional layer, and can be laminated by various printing methods such as vapor deposition, sputtering, coating, gravure printing or offset printing, thermal bonding, lamination via an adhesive layer, etc. For example, when the polyhydroxyalkanoic acid film of the present invention is used for packaging purposes, it is preferred to select a coating, vapor deposition layer, or heat-sealing layer that imparts gas barrier properties as the functional layer. For example, when the polyhydroxyalkanoic acid film of the present invention is used for coating agricultural, forestry and aquatic raw materials such as fertilizers, feeds, seedlings, and medicaments, it is preferred to select an adhesive layer that imparts pressure-bonding properties or a heat-sealing layer that imparts thermal pressure-bonding properties as the functional layer that imparts adhesion. In addition, from the viewpoint of not damaging the effects of the present invention, it is preferred that the functional layer has biodegradability or low toxicity. Regarding the functional layer that can be preferably stacked, for example, when used for packaging purposes or agricultural, forestry and aquatic products, it is preferred that a coating or vapor-deposited layer that imparts gas barrier properties be used. From the viewpoint of being able to exert high gas barrier properties, the functional layer is more preferably a vapor-deposited layer.

[0073] When the polyhydroxyalkanoic acid film of the present invention is laminated with a deposited layer as a functional layer, the deposited layer is preferably laminated on at least one side of the film. Furthermore, from the perspective of gas barrier properties, the deposited layer is preferably a layer (D layer) containing a total of more than 50% by mass and less than 100% by mass of metal and inorganic compounds. Here, the term "layer containing a total of more than 50% by mass and less than 100% by mass of metal and inorganic compounds" refers to any of the following: a layer containing more than 50% by mass of metal alone, a layer containing more than 50% by mass of inorganic compounds alone, or a layer containing both metal and inorganic compounds, with the total amount exceeding 50% by mass, when all components constituting the layer are set to 100% by mass. As the metal and / or inorganic compound that can be used in the D layer, from the perspective of improving adhesion to the film, gas barrier properties when laminated to the film, and reducing environmental load, preferably aluminum, aluminum oxide, silicon oxide, germanium oxide, magnesium oxide, cerium oxide, calcium oxide, diamond-like carbon film, or a mixture thereof is used. Furthermore, from the perspective of visibility of the contents, inorganic compounds are more preferably used, particularly aluminum oxide, silicon oxide, or mixtures thereof. The thickness of the D layer in the laminate is preferably 200 nm or less, from the perspective of recyclability when the laminate is reused as a resin or film, from the perspective of preventing cracking that reduces gas barrier properties, and from the perspective of ensuring visibility of the contents when used as a packaging material. From these perspectives, the thickness of the D layer in the laminate is more preferably 110 nm or less, further preferably 50 nm or less, and particularly preferably 30 nm or less. While there is no particular lower limit, from the perspective of barrier performance, the thickness of the D layer in the laminate is preferably 1 nm or greater.

[0074] In the laminate of the present invention, a resin layer having a thickness of 1 μm or less is provided between the D layer and the surface of the polyhydroxyalkanoic acid film by coating or the like. The provision of this resin layer may sometimes provide effects such as improved adhesion between the D layer and the polyhydroxyalkanoic acid film. However, from the perspective of manufacturing costs, a configuration without this resin layer, that is, a configuration in which the D layer is directly laminated on the outermost surface of the polyhydroxyalkanoic acid film, is preferred.

[0075] Methods for forming the D layer as a laminate on the polyhydroxyalkanoic acid film of the present invention include coating, vapor deposition, and lamination. However, vapor deposition is particularly preferred because it is not humidity-dependent and can exhibit excellent gas barrier properties even with a thin film. Vapor deposition methods include physical vapor deposition methods such as vacuum vapor deposition, EB (electron beam) vapor deposition, sputtering, and ion plating, and various chemical vapor deposition methods such as plasma CVD. However, vacuum vapor deposition is particularly preferred from the perspective of productivity.

[0076] Furthermore, in the laminate of the present invention, a coating layer may be provided on the D layer from the viewpoint of improving the gas barrier properties and suppressing a decrease in the gas barrier properties due to vapor deposition defects or cracks in the D layer.

[0077] When a layer (E layer) imparting adhesion, such as an adhesive layer or a heat seal layer, is laminated on the polyhydroxyalkanoic acid film of the present invention as a functional layer, it is preferably laminated on at least one side of the film. As the resin component for the E layer, from the viewpoint of high heat seal strength, preferably used are polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-propylene random copolymer, ethylene-propylene block copolymer, ethylene-methacrylic acid copolymer, or mixtures thereof. When laminating a plurality of films, from the viewpoint of reducing the thickness of the final product, for example, ethylene-vinyl acetate copolymer (EVA)-based hot melt adhesives, olefin-based hot melt adhesives, rubber-based hot melt adhesives, polyester-based hot melt adhesives, polyamide-based hot melt adhesives, polyurethane-based hot melt adhesives, or mixtures thereof are more preferably used. From the viewpoint of improving the biodegradability of the entire laminate, for example, resin components obtained by adjusting the copolymerization components of the polyhydroxyalkanoic acid exemplified above, biodegradable resins having a softening temperature or melting point lower than that of the polyhydroxyalkanoic acid film of the present invention, such as polylactic acid, polyglycolic acid, and polybutylene succinate, or mixtures thereof are more preferably used.

[0078] From the perspective of achieving high adhesive strength, the thickness of the E layer in the laminate is preferably 0.5 μm or greater, more preferably 1.0 μm or greater, and even more preferably 3.0 μm or greater. Furthermore, from the perspective of suppressing a decrease in the biodegradability of the laminate and suppressing the thickness of the final product when multiple films are laminated, the thickness of the E layer in the laminate is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less.

[0079] In addition, in the laminate, a resin layer having a thickness of 1 μm or less is provided between the E layer and the surface of the polyhydroxyalkanoic acid film by coating or the like. The provision of this resin layer can sometimes achieve effects such as improved adhesion between the E layer and the polyhydroxyalkanoic acid film. However, from the perspective of manufacturing costs, a configuration without this resin layer (i.e., a configuration in which the E layer is directly laminated on the outermost surface of the polyhydroxyalkanoic acid film) is preferred, and a configuration in which the E layer is provided on the surface of the polyhydroxyalkanoic acid film is more preferred.

[0080] As a method for forming an E layer on the polyhydroxyalkanoic acid film of the present invention to prepare a laminate, coating or lamination is particularly preferred. As a coating method, rod coating, gravure coating, calendar coating, die coating, etc. can be used. As a lamination method, dry lamination, solventless lamination, extrusion lamination, coextrusion, etc. can be used. From the viewpoint of productivity, gravure coating, die coating, extrusion lamination, and coextrusion are more preferably used.

[0081] <Packaging materials and packaging body>

[0082] The packaging material and packaging body of the present invention are described below. The packaging material of the present invention is characterized by using at least one of the polyhydroxyalkanoic acid film of the present invention and the laminate of the present invention. The packaging material of the present invention does not crack or deform even under the conveying tension of the vapor deposition process of the vapor-deposited layer provided as a gas barrier layer, and has excellent gas barrier properties. Therefore, it is well suited for packaging substances that are easily degraded by water vapor or oxygen.

[0083] The packaging body of the present invention is characterized in that the contents are packaged using the packaging material of the present invention. There are no particular restrictions on the contents, but since the packaging material of the present invention has excellent transparency and gas barrier properties, the contents are preferably those that require external visibility and are easily degraded by water vapor or oxygen. In addition, the packaging body of the present invention is obtained by coating the contents with the packaging material of the present invention, and its form is not particularly limited. For example, a packaging body obtained by heat-sealing the packaging material of the present invention into a bag shape and placing the contents therein, a packaging body obtained by filling or placing the contents in a tray-shaped container and then sealing it with the packaging material of the present invention, etc.

[0084] <Agriculture, forestry and fishery materials>

[0085] The agricultural, forestry, and aquatic industry material of the present invention is described below. The agricultural, forestry, and aquatic industry material of the present invention is characterized by using at least one of the polyhydroxyalkanoic acid membrane of the present invention and the laminate of the present invention. The agricultural, forestry, and aquatic industry material of the present invention is characterized by being biodegradable and can be used as a material that biodegrades after use, such as a multilayer soil film, vegetation film, fumigation film, water retention film, fertilizer coating material, feed coating material, seedling coating material, drug coating material, aquaculture support film, marine biofouling inhibitory film, and environmental protection material.

[0086] <Coating films for agricultural, forestry, and fishery raw materials>

[0087] The polyhydroxyalkanoic acid film of the present invention is used to coat agricultural, forestry and fishery raw materials containing one or more selected from fertilizers, feeds, seedlings and chemicals, thereby protecting the coated agricultural, forestry and fishery raw materials and preventing deterioration and quality reduction or leakage and environmental pollution. At the same time, by biodegrading in the soil or the ocean, the fertilizers, feeds and chemicals can be diffused and scattered at an appropriate time, or biodegraded after the protection period until the seedlings are fixed and implanted, thereby preventing them from hindering their growth. The agricultural, forestry and fishery raw materials here refer to the original materials and components contained in the agricultural, forestry and fishery materials. As long as the effects of the present invention are not impaired, there is no particular limitation, and a wide range of known materials can be used. As described above, by using the polyhydroxyalkanoic acid film of the present invention with excellent biodegradability, high strength and moderate flexibility for this purpose, it is possible to prevent the agricultural, forestry and fishery raw materials as the contents from leaking from pinholes, cracks, and parts with uneven coating thickness. The diffusion and scattering speed in the soil or the ocean can be controlled by the thickness of the polyhydroxyalkanoic acid film of the present invention. In addition, two or more of the agricultural, forestry and aquatic products raw materials of fertilizers, feeds, seedlings and medicaments can be coated together. For example, by coating seedlings with the fertilizers and medicaments that they want to act on, it is possible to improve the growth of crops when they germinate, which is therefore preferred.

[0088] From this perspective, the thickness of the polyhydroxyalkanoic acid film is preferably selected within the preferred range based on the diffusion and dispersion speed in the soil or ocean. If the polyhydroxyalkanoic acid film is too thin, the strength is insufficient, the protectiveness of the contents is reduced, or it may crack during processing. In addition, if the polyhydroxyalkanoic acid film is too thick, the flexibility is insufficient, and it is sometimes difficult to process into the preferred shape described below. For example, for fast-acting fertilizers, a thin film can be selected that diffuses and disperses quickly after biodegradation, while for slow-acting fertilizers, a thick film can be selected that diffuses and disperses slowly after biodegradation. By broadcasting these coated fertilizers together, the workload of agricultural workers can be reduced.

[0089] Furthermore, the characteristics of the polyhydroxyalkanoic acid membrane of the present invention can be utilized to create a multilayer coating layer. Specifically, after coating a slow-acting fertilizer with the polyhydroxyalkanoic acid membrane of the present invention, the surrounding layer can be coated with a fast-acting fertilizer and the polyhydroxyalkanoic acid membrane of the present invention. This allows the slow-acting fertilizer and the fast-acting fertilizer to be sequentially coated with the polyhydroxyalkanoic acid membrane of the present invention to produce the same fertilizer. Furthermore, by sequentially coating seedlings with fertilizer, feed, or chemicals using the same method, it is possible to achieve the desired effect of allowing the fertilizer, feed, or chemicals to act on growing agricultural and aquatic products at the appropriate time.

[0090] As described above, agricultural, forestry, and fishery raw materials characterized by being coated with the polyhydroxyalkanoic acid membrane of the present invention can prevent accidental leakage and cause environmental pollution, while particularly improving the effectiveness of agricultural, forestry, and fishery raw materials selected from fertilizers, feeds, seedlings, and pesticides. By diffusing and scattering in the soil or the ocean at appropriate times, the efficacy can be improved and the workload of operators can be reduced, and they can be particularly well used in the agricultural, forestry, and fishery fields.

[0091] The form of fertilizers, feeds, seedlings, and pharmaceuticals characterized by being coated with the polyhydroxyalkanoic acid film of the present invention is not particularly limited as long as the effects of the present invention are not impaired, and they can be used in various forms such as pellets, granules, blocks, bags, ropes, and sheets. Specifically, for coated fertilizers for agricultural use, blocks, pellets, and granules are preferred, which are compatible with spreaders. For coated seedlings, ropes or sheets are preferred, as they can be expected to reduce workload.

[0092] <Manufacturing method>

[0093] Hereinafter, a preferred embodiment of the method for producing the polyhydroxyalkanoic acid film of the present invention will be described.

[0094] A preferred embodiment of the method for producing a polyhydroxyalkanoic acid film of the present invention sequentially comprises the following steps: a melting step of melting a polyhydroxyalkanoic acid resin, a casting step of discharging the melted polyhydroxyalkanoic acid resin from a die into a sheet, cooling and solidifying the sheet on a support, a stretching step of stretching the polyhydroxyalkanoic acid sheet in two orthogonal directions, and a heat treatment step of subjecting the film obtained by the stretching step to heat treatment and relaxation. The polyhydroxyalkanoic acid film of the present invention is not particularly limited in layer structure; for example, two types of two-layer structures (layer A / layer B), two types of three-layer structures (layer A / layer B / layer A), and three types of three-layer structures (layer A / layer B / layer C (layer C represents a layer different from layer A and layer B)) may be employed. The following description of the production method will be more specifically described using a single-layer polyhydroxyalkanoic acid film composed of layer A as an example, but the polyhydroxyalkanoic acid film of the present invention and its production method are not necessarily limited to this description.

[0095] First, a polyhydroxyalkanoic acid resin is melted using a single-screw extruder. The extrusion temperature is set at 150°C to 220°C, and the melt is extruded through a filter to remove foreign matter. The molten resin is then extruded through a slit die. To prevent degradation of the polyhydroxyalkanoic acid resin and improve the puncture strength of the film, the oxygen concentration in the raw material feed hopper is preferably controlled to 0.10% by volume or less.

[0096] Next, the molten resin sheet extruded from the slit die is cooled and solidified on a casting drum whose surface temperature is controlled at 10°C to 40°C, thereby obtaining an unstretched polyhydroxyalkanoic acid film. The molten sheet can be adhered to the casting drum by any of the following methods: electrostatic application, adhesion utilizing the surface tension of water, air knife, pressure roll, underwater casting, and air chamber methods. A combination of these methods may also be used.

[0097] Here, in the polyhydroxyalkanoic acid film of the present invention, from the viewpoint of improving the film strength after biaxial stretching, it is preferred to use a method in which the film transport speed at the longitudinal stretching inlet, which is the next step, is adjusted to be faster relative to the speed at the casting drum outlet, thereby improving the molecular chain orientation of the unstretched polyhydroxyalkanoic acid film. More specifically, it is preferred that the film transport speed at the longitudinal stretching inlet is 101% or more and 125% or less relative to the speed at the casting drum outlet. From the viewpoint of achieving a better effect of improving the puncture strength of the film, the film transport speed at the longitudinal stretching inlet is more preferably 103% or more, and more preferably 106% or more, relative to the speed at the casting drum outlet. On the other hand, with respect to the upper limit, from the viewpoint of productivity such as film rupture, the upper limit of the film transport speed at the longitudinal stretching inlet is more preferably 116% or less, and more preferably 112% or less, relative to the speed at the casting drum outlet.

[0098] Next, a uniaxially oriented film is obtained by a longitudinal stretching process. In the longitudinal stretching process, a plurality of roller groups are used for preheating for more than 1 second and less than 1000 seconds. The preheating temperature is preferably the same temperature as the casting drum temperature or more, more preferably the casting drum temperature + 10°C or more, and the preheating temperature is preferably the casting drum temperature + 50°C or less, more preferably the casting drum temperature + 40°C or less. Preheating is performed by passing between rollers maintained at a preheating temperature. At this time, by making the preheating temperature the same temperature as the casting drum temperature or more and the casting drum temperature + 50°C or less, the growth of spherulites and the spherulite phase transition before stretching can be controlled, and stable stretching can be achieved even at a high ratio. Next, before stretching, the polyhydroxyalkanoic acid film is kept at a temperature of more than 100°C and less than the melting point of the polyhydroxyalkanoic acid resin for a time of more than 0.1 second and less than 100 seconds at this temperature, and stretched in the longitudinal direction by more than 1.5 times and less than 10 times at this temperature. From the perspective of improving puncture strength and film formation stability, the stretch ratio in the longitudinal direction is preferably 1.6 times or greater, more preferably 2.1 times or greater, even more preferably 2.4 times or greater, and particularly preferably 2.6 times or greater. On the other hand, the stretch ratio is preferably 8 times or less, even more preferably 4 times or less. After longitudinal stretching, the film is cooled to room temperature to obtain a uniaxially oriented film.

[0099] Next, while the ends of the uniaxially oriented film are gripped with clips, the film is guided to a tenter. While the film ends are gripped with clips, the film is maintained at a temperature of 60°C or higher and below the melting point of the polyhydroxyalkanoic acid resin. While maintaining this temperature, the film is stretched in the width direction at a ratio of 1.5 to 10 times (transverse stretching). From the perspective of improving puncture strength and film production stability, the stretch ratio in the width direction is preferably 1.6 times or higher, more preferably 2.1 times or higher, even more preferably 2.4 times or higher, and particularly preferably 2.6 times or higher. On the other hand, the stretch ratio is preferably 8 times or lower, and even more preferably 4 times or lower.

[0100] Here, the area stretching ratio is preferably 4 times or more. By setting the area stretching ratio to 4 times or more, the molecular chain tension in the film surface is increased, the crystallite size is also reduced, the puncture strength of the film can be increased, and appropriate deformation is provided in the surface, thereby preventing expansion during heating. When the D layer is formed as a laminate by vapor deposition, defects such as pinholes or cracks in the D layer can be suppressed, that is, the so-called heat loss or wrinkling phenomenon can be suppressed. The area stretching ratio is more preferably 6 times or more, and more preferably 8 times or more. There is no particular limit on the upper limit of the area stretching ratio, but from the perspective of feasibility, the area stretching ratio is 50 times or less, more preferably 35 times or less, and more preferably 20 times or less in the case of successive biaxial stretching.

[0101] In the manufacture of the polyhydroxyalkanoic acid film of the present invention, it is preferred to perform heat treatment and relaxation treatment after transverse stretching. In the heat treatment and relaxation treatment, while the two ends in the width direction are tightly gripped with the clips of the tenter, a relaxation of 2% or more and 20% or less is applied in the width direction at a speed of 10% or more and 500% or less / min, and the treatment is preferably performed at a temperature of 50°C or more and 150°C or less for 1 second or more and 100 seconds or less. The heat treatment temperature is more preferably 55°C or more, and more preferably 60°C or more, and the heat treatment temperature is more preferably 145°C or less, and more preferably 140°C or less. The relaxation treatment speed is more preferably 350% / min or less, and more preferably 200% / min or less, and the relaxation treatment speed is more preferably 15% / min or more, and more preferably 20% / min or more. The heat treatment time is more preferably 60 seconds or less, and more preferably 45 seconds or less. The heat treatment time is more preferably 4 seconds or more, and more preferably 8 seconds or more. By performing the relaxation and heat treatment, the structural stability of the film relative to heat can be improved. When forming the D layer by vapor deposition to form a laminate, heat resistance phenomena such as defects such as pinholes and cracks in the D layer can be suppressed. As a result, the barrier properties of the laminate obtained from the polyhydroxyalkanoic acid film can be improved. During the relaxation treatment, from the perspective of improving the structural stability of the film relative to heat, the relaxation rate is more preferably 2% or more, and more preferably 4% or more. In addition, the relaxation rate is more preferably 15% or less, and more preferably 11% or less. When the relaxation rate is less than 2%, the resulting polyhydroxyalkanoic acid film may have poor dimensional stability when heated. Therefore, when forming the D layer by vapor deposition to form a laminate, the film may deform and defects such as pinholes or cracks may be generated in the D layer, resulting in a decrease in the barrier properties of the laminate with the D layer. On the other hand, when the relaxation rate exceeds 20%, the film relaxes excessively inside the tenter, resulting in wrinkles in the film after film formation, which may lead to reduced mechanical properties or unevenness during vapor deposition.

[0102] After the heat treatment, the film is guided outside a tenter frame, and the clamps at both ends of the film in the width direction are released at room temperature. During the winding process, the edges on both sides of the film are trimmed. Subsequently, the surface on which the layer containing a combined metal and inorganic compound content of greater than 50% by mass and less than 100% by mass (layer D) is to be laminated (typically the surface in contact with the casting drum) is preferably subjected to a surface modification treatment such as corona treatment inline to improve adhesion with layer D. The resulting film is wound into a roll to produce the polyhydroxyalkanoic acid film of the present invention.

[0103] Next, methods for producing fertilizers, feeds, seedlings, and pharmaceuticals coated with the polyhydroxyalkanoic acid film of the present invention will be described in more detail with reference to examples, but the present invention is not necessarily limited thereto.

[0104] The method for producing a fertilizer coated with a polyhydroxyalkanoic acid film of the present invention involves guiding the polyhydroxyalkanoic acid film obtained by the above method between upper and lower molds formed into a projectile-shaped recess. Suction is then applied to seal the film to the molds. Next, the fertilizer to be coated is spread on the film of the lower mold, and the upper mold is lowered and heated to bond the upper and lower films.

[0105] The fertilizer coated with the polyhydroxyalkanoic acid film of the present invention may be in the form of pellets, granules, powders, pastes, or liquids. However, from the perspectives of ease of film protection and conformability to mold shapes, the fertilizer is preferably in the form of granules, powders, pastes, or liquids.

[0106] In addition, from the viewpoint of adhesiveness, it is preferred to provide the heat seal layer as an adhesive layer (E layer) on the polyhydroxyalkanoic acid film of the present invention. In this case, it is more preferred to arrange the E layer on the mold so that it is located on at least one side of the surfaces where the films are in contact with each other.

[0107] Next, the fertilizer-coated film is removed from the mold, and the excess film-bonded portions are cut and removed, thereby obtaining pellet-shaped coated fertilizer. A cutting machine equipped with a cutter is preferably used for cutting. Examples of such methods include batch processing of individual films using a mold pre-equipped with a cutter, continuous cutting in one direction using a rotating cutter to form a rope, followed by periodic cutting in an orthogonal direction, and simultaneous thermocompression and cutting using a cutter mounted on the mold.

[0108] Other methods for coating agricultural, forestry, and fishery raw materials include a method of pre-preparing two rolls of the polyhydroxyalkanoic acid film of the present invention, inserting the agricultural, forestry, and fishery raw materials between them at a certain period, and laminating them; a method of coating the agricultural, forestry, and fishery raw materials by heating them while they are held on the film to cause them to heat shrink; and a method of coating the film by shrinking it under reduced pressure.

[0109] The present invention can obtain fertilizers, feeds, seeds, and medicines coated with the polyhydroxyalkanoic acid film of the present invention having excellent biodegradability, strength, and flexibility through such a production method.

[0110] <Decomposition method>

[0111] The polyhydroxyalkanoic acid film of the present invention, the packaging containing the polyhydroxyalkanoic acid film, and agricultural, forestry, and fishery materials can be biodegraded in composting equipment. Composting equipment includes commonly known equipment such as industrial composting that increases biodegradability by heating or maintaining the temperature at approximately 60°C, simple composting made by digging holes in the soil, small-scale composting such as compost containers or compost bags partially or completely buried in the soil, and composting using organisms such as earthworms or flies. If the polyhydroxyalkanoic acid film of the present invention, the packaging containing the polyhydroxyalkanoic acid film, or agricultural, forestry, and fishery materials do not have a functional layer, or if the functional layer is a biodegradable or low-toxic vapor-deposited layer, they can be decomposed by placing them in a composting equipment and subjecting them to standard treatment, such as mixing with soil or a decomposition material containing a microbial fermentation-promoting material. Furthermore, when a non-biodegradable functional layer or other layer is used, the functional layer can be removed and placed in a composting facility. If the layer is low in toxicity, such as environmental or human toxicity, even if it is non-biodegradable, it can be placed in a composting facility, and the residue can be recovered after the polyhydroxyalkanoic acid film of the present invention decomposes. The purposes of composting include waste reduction through volume reduction, composting, and biogas generation. However, the polyhydroxyalkanoic acid film, packaging, and agricultural, forestry, and fishery materials of the present invention are suitable for use in composting facilities for any purpose.

[0112] Example

[0113] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following embodiments.

[0114] <Methods for measuring characteristic values ​​and evaluating effects>

[0115] The method for measuring the characteristic values ​​and the method for evaluating the effects of the present invention are as follows.

[0116] (1) Film thickness

[0117] The thickness of the polyhydroxyalkanoic acid film was measured at five random locations using a contact-type, high-precision digital length measuring machine (LITEMATIC VL50B) manufactured by Mitutoyo at 23°C and 65% RH. The arithmetic mean of the thicknesses at the ten locations was taken as the film thickness (unit: μm).

[0118] (2) Determination of the main orientation axis direction and the direction orthogonal to the main orientation axis direction

[0119] The main orientation axis is defined as the flow direction (MD) during the film production process, and the direction (TD) perpendicular to the flow direction in the film plane is defined as the direction perpendicular to the main orientation axis. For films with unknown orientation, cut a rectangular sample with a length of 150 mm and a width of 10 mm with any direction facing upward. <1> , the sample <1> The long side direction is set to 0°. Next, collect samples of the same size with the long side direction rotated 15° to the right from the 0° direction. <2> . Similarly, the long side direction of the rectangular sample is rotated multiple times, each time by 15°, and samples <3> to <12> are collected in the same manner. Next, each rectangular sample is placed on a tensile testing machine ("TENSILON Universal Testing Machine" RTG-1210 manufactured by A & D) with the long side direction as the tensile direction, with the initial chuck distance being 30 mm, and a tensile test is performed at a tensile speed of 300 mm / min in an atmosphere of temperature and humidity of 25±5°C and 65±10%RH. At this time, the maximum load until the sample breaks is read and divided by the cross-sectional area of ​​the sample before the test (film thickness × width determined in (1)), and the resulting value is used as the breaking strength to calculate. The same measurement is performed 5 times for each sample, and the average value of the breaking strength is used as the breaking strength of the sample (unit: MPa). The long side direction of the sample with the largest value is used as the main orientation axis direction of the polyhydroxyalkanoic acid film. In addition, the direction perpendicular to it is used as the direction perpendicular to the main orientation axis direction of the polyhydroxyalkanoic acid film.

[0120] (3) Puncture strength and puncture displacement

[0121] The membrane puncture strength (Force) and strain (Strain) were measured according to JIS Z1707 (2019) under the following conditions. Five measurements were performed, and the average of the values ​​was calculated by dividing each measured value by the measured membrane thickness (μm) and multiplying by 20 (μm). The average of these values ​​was used as the puncture strength (value converted to a thickness of 20 μm). The strain was calculated by taking the shorter of the five measured values, the distance from the tip of the measuring needle contacting the membrane until a hole or tear in the membrane was formed.

[0122] Equipment: HANDY-TYPE COMPRESSION TESTERKES-G5, a small compression tester produced by KATOTECH

[0123] Measurement conditions: Sensitivity: 10 Speed: 0.20 cm / s Stroke: 20mm / 10V Needle diameter: 1.0mm

[0124] Aperture: 10.0mm .

[0125] (4) Breaking strength in the direction of the main orientation axis (S1) and the breaking strength in the direction perpendicular to the main orientation axis (S2)

[0126] Tensile tests were conducted in the main orientation axis direction and in the direction perpendicular to the main orientation axis direction using the same sample size, tensile testing machine, and measurement conditions as in (2). The measurements were performed five times, and the average value of the breaking strength at break was calculated as the breaking strength (S1) in the main orientation axis direction and the breaking strength (S2) in the direction perpendicular to the main orientation axis direction of the polyhydroxyalkanoic acid film (both units: MPa).

[0127] (5) Shrinkage start temperature T1 in the main orientation axis direction and shrinkage start temperature T2 in the direction perpendicular to the main orientation axis direction measured by thermomechanical analysis (TMA)

[0128] A rectangular sample with a width of 4 mm and a length of 50 mm was cut, with the main orientation axis and the direction perpendicular to the main orientation axis as the long sides. The sample was clamped in the metal chuck of the following thermomechanical analysis apparatus, with the test length of 10 mm. Then, the thermal shrinkage curves in the direction perpendicular to the main orientation axis and in the direction perpendicular to the main orientation axis were calculated for the film while maintaining the test length under the following temperature and load conditions. The temperatures at which the film shrinks by 1% in both the main orientation axis and the direction perpendicular to the main orientation axis were read and used as the shrinkage start temperature (T1) in the main orientation axis direction and the shrinkage start temperature (T2) in the direction perpendicular to the main orientation axis direction (both in °C).

[0129] Device: TMA / SS6000 (manufactured by Seiko Instruments Co., Ltd.)

[0130] (Temperature conditions) Temperature: Initial temperature 25°C, Maximum temperature: 160°C, Heating rate: 10°C / min Holding time after reaching maximum temperature: 10 minutes Nitrogen cooling: No (Loading conditions) Control mode: F mode (load control mode with constant load) Load: 29.4mN (constant) (6) ㅣN1-N2ㅣ is calculated from the refractive index N1 at a wavelength of 1550nm in the direction of the main orientation axis and the refractive index N2 at a wavelength of 1550nm in a direction perpendicular to the main orientation axis. The in-plane refractive index N1 in the main orientation axis direction and the in-plane refractive index N2 in a direction perpendicular to the main orientation axis direction were measured using a prism coupler, and the absolute value of the difference between them was calculated.

[0131] Device: PRISM COUPLER & LOSS MEASUREMENT SPA-4000 manufactured by SAIRON TECHNOLOGY, INC. AIR PRESSURE (propulsion pressure): 0.5MPa Prism: GGG (gadolinium gallium garnet. n = 1.965) Light source: 1550nm diode laser.

[0132] (7) Birefringence (N12-Nz)

[0133] The refractive index Nz in the thickness direction was measured by the same measurement method as (6), and the birefringence in the thickness direction was calculated by the following formula.

[0134] Birefringence (N12-Nz) = |(N1+N2) / 2-Nz|

[0135] (8) Elongation at break in the direction of the main orientation axis (L1) and in the direction perpendicular to the main orientation axis (L2)

[0136] Tensile tests were conducted in the main orientation axis direction and in the direction perpendicular to the main orientation axis direction using the same sample size, tensile testing machine, and measurement conditions as in (2). The measurements were performed five times, and the average elongation at break of the sample was calculated as the elongation at break in the main orientation axis direction (L1) and the elongation at break in the direction perpendicular to the main orientation axis direction (L2) of the polyhydroxyalkanoic acid film (both in %).

[0137] (9) Melting point of polyhydroxyalkanoic acid resin and film

[0138] Measurements and analyses were performed using a differential scanning calorimeter (Rigaku, Thermoplus EVO2 DSC vesta) in accordance with JIS K7121-1987 and JIS K7122-1987. A 5.0 mg sample was weighed, and the temperature at the top of the endothermic peak, as determined by the DSC curve when the temperature was raised from -50°C to 200°C at a rate of 20°C / minute under a nitrogen atmosphere, was used as the melting point of the polyhydroxyalkanoic acid resin and film. If multiple endothermic peaks were present, the peak with the highest endothermic value was used.

[0139] (10) Weight average molecular weight Mw of the resin

[0140] 5 mL of the measurement solvent described below was added to 10 mg of the sample and stirred at room temperature until the sample dissolved. The solution was then filtered using a 0.45 μm filter and the weight average molecular weight Mw was determined using gel permeation chromatography (GPC) under the following conditions.

[0141] Detector: Differential refractive index detector RI (Tosoh RI-8020, sensitivity 32) Chromatographic columns: TSKgel GMHHR-M (7.8 mm × 30 cm, manufactured by Tosoh), 2 Solvent: Chloroform Flow rate: 1.0 mL / min Column temperature: 40°C Injection volume: 0.200mL Standard sample: Monodisperse polystyrene manufactured by Tosoh Data processing: GPC data processing system manufactured by Toray Research Center.

[0142] (11) Crystallite size

[0143] (11-1) Acquisition of two-dimensional diffraction images

[0144] The film sample is cut into such sizes as 2 cm along the main orientation axis and 1 cm along the direction perpendicular to the main orientation axis, and several sheets with a total thickness of 100 μm or more are directly overlapped in such a manner that the main orientation axis direction is the same direction. At the center of the sample, the sample is fixed on a holder in such a manner that X-rays can be incident on the center of the sample in a direction perpendicular to the main orientation axis direction. Then, reflection measurement in the film thickness direction is performed under the following conditions to obtain a two-dimensional X-ray diffraction image.

[0145] Device: D8 DISCOVER μHR Hybrid, manufactured by Bruker AXS

[0146] X-ray source: CuKα line (using a multilayer mirror), wavelength λ = 0.15418nm

[0147] Output: 50kV, 22mA

[0148] Slit system: (X-ray source side) 1mm 2 -1mm 2-0.1mmΦ (sample side)

[0149] Detector: 2D detector (Vantec500)

[0150] Scan: 2θ = 20°

[0151] Elevation angle: ω = 10°

[0152] Camera length: 10cm

[0153] Cumulative time: 300 seconds / frame.

[0154] (11-2) Orientation profile curve

[0155] Based on the diffraction pattern obtained in (11-1), the diffraction angle (2θ) was scanned from 40° to 140° with a 0.5° scale in the range of 19° to 21°, with a circumferential angle of 90° in the thickness direction, and the results were integrated to obtain an orientation profile curve.

[0156] (11-3) Orientation angle and orientation degree

[0157] Using the minimum value of the orientation distribution obtained in (11-2) as the baseline, use a Gaussian distribution function to isolate the peak with the highest intensity among those with an orientation degree of 0.50 or greater within the diffraction angle 2θ range of 19° to 21°. The peak position at this point is the orientation angle (°). The orientation degree of PB is calculated from the peak's half-width (HWH) using the following formula.

[0158] Degree of orientation = (180-HO) / 180.

[0159] 2θ profile curve in the (11-4) orientation direction

[0160] The range of ±10° of the orientation angle obtained from (11-3) was scanned with 0.05° as a scale, and the results were integrated to obtain a 2θ profile curve.

[0161] (11-5) Crystallite size

[0162] The baseline was set using the minimum value of the 2θ profile curve obtained from (11-4). Using a Gaussian distribution function, the peak with the highest intensity among the peaks with an orientation degree of 0.50 or greater within the diffraction angle (2θ) range of 19° to 21° was separated. The crystallite size (nm) was calculated using the Scherrer equation based on the half-peak width of the separated peak. The Scherrer constant was 0.9, and the correction value for the half-peak width was determined from the Si diffraction peak (111) measured using the above-mentioned optical system using standard Si powder for X-ray diffraction produced by NIST.

[0163] (12) The thermal shrinkage H1 in the main orientation axis direction and the thermal shrinkage H2 in the direction perpendicular to the main orientation axis direction of the film were obtained by heating at 120°C for 15 minutes.

[0164] For the main orientation axis and the direction perpendicular to the main orientation axis, the film was cut into a rectangle with a length of 150 mm and a width of 10 mm. A mark was made with an oil-based marker within the central 100 mm area, and the length was measured using a multi-purpose projector to determine the initial length I0. The measured sample was then placed in a gear-type hot air oven adjusted to 120°C. A load of 2.1 g was applied to the bottom of the suspended film, and the heat treatment was performed for 15 minutes while the gears rotated. The film was then removed and cooled to room temperature. The length between the marks was measured using a multi-purpose projector to determine the thermal shrinkage IH. Based on the measured I0 and IH, the 120°C thermal shrinkage (unit: %) was calculated using the following formula (5). The same measurement was performed five times in each of the main orientation axis direction and the direction perpendicular to the main orientation axis direction for each sample. The average value in the main orientation axis direction was recorded as H1 (%), and the average value in the direction perpendicular to the main orientation axis direction was recorded as H2 (%).

[0165] Thermal yield at 120°C (%) = (I0-IH) / I0×100 Formula (5).

[0166] (13) Content of polyhydroxyalkanoic acid resin

[0167] The aliphatic polyester film was dissolved in hexafluoroisopropanol (HFIP) and 1 H-NMR and 13 The content (mass %) of the polyhydroxyalkanoic acid resin was measured by C-NMR. In the Examples and Comparative Examples, the composition was calculated based on the resin content during film production.

[0168] (14) Biodegradability

[0169] 1 L of wet synthetic compost was prepared according to JIS K6954 (2008) and placed in a 10 L polypropylene container. Next, a 5 cm x 5 cm evaluation film was placed between a polyethylene holder with a 2 cm square cut out inside, exposing the film inside the holder.

[0170] The membrane sample, secured by a retainer, was then placed in moist compost within a polypropylene container. The incubation test was conducted for 60 days in an oven maintained at 28±2°C, according to JIS K6954 (2008). During the placement of the membrane sample, the entire 2 cm square of membrane exposed within the retainer was covered by the moist compost. After the initial placement, the membrane sample was removed every two days, stirred with a shovel, and then the membrane sample was repeatedly added.

[0171] 60 days after the initial placement, the membrane sample was removed from the container and photographed with a digital camera. The photographs must have a resolution of 1200 dpi (2 million pixels) or higher. Based on the photographed image, the area of ​​the sample remaining within a 2 cm square frame inside the retainer was calculated. The breakdown area ratio (%) was calculated using the formula: (Initial sample area within the retainer - Remaining sample area within the retainer) / (Initial sample area within the retainer) × 100. A total of three retainers were evaluated in the same compost pile, and the arithmetic average of the three measured values ​​was used as the membrane sample breakdown area ratio (%). The following criteria were used for evaluation.

[0172] A: The collapse area ratio is more than 60%

[0173] B: The collapse area ratio is 40% or more and less than 60%

[0174] C: The collapse area ratio is 20% or more and less than 40%

[0175] D: The collapse area ratio is 5% or more and less than 20%

[0176] E: The collapse area ratio is less than 5%

[0177] The biodegradability of the film is preferably D or higher.

[0178] (15) The occurrence of rupture when changing the conveying speed and tension

[0179] A film 300 mm wide and 200 m long (6-inch, 350 mm long core roll) was prepared and wound (rewound) onto a 3-inch, 350 mm long core under the following conditions. Evaluation was performed based on the following criteria while increasing the feed speed and tension.

[0180] A: Even when rewinding at a speed of 10 m / min and a conveying tension of 70 N / m, no tearing occurs.

[0181] B: No cracks occurred even when the rewind was performed at a speed of 8 m / min and a feed tension of 70 N / m. However, cracks occurred when the speed was increased to 10 m / m and the feed tension was increased to 70 N / m.

[0182] C: No cracks occurred even when the rewind was performed at a speed of 5 m / min and a feed tension of 70 N / m. However, cracks occurred when the speed was increased to 8 m / min and the feed tension was increased to 70 N / m.

[0183] D: No cracks occurred even when the rewinding was performed at a speed of 5 m / min and a feed tension of 50 N / m. However, cracks occurred when the speed was increased to 5 m / min and the feed tension was increased to 70 N / m.

[0184] E: The film broke when it was unwound at a speed of 5 m / min and a conveying tension of 50 N / m.

[0185] The processability of the film is preferably D or higher.

[0186] (16) Water vapor barrier properties after Al evaporation

[0187] <Al Vapor Deposition Method>

[0188] The film was placed in a vacuum deposition apparatus equipped with a film travel device, and the film was placed in a vacuum deposition apparatus equipped with a film travel device. -2 After a highly reduced pressure of 100 Pa, the film was run on a cooled metal drum at 20°C while heating and evaporating aluminum metal, forming a vapor-deposited thin film layer on the film. The thickness of the vapor-deposited film was controlled to 100 nm. After vapor deposition, the vacuum deposition apparatus was returned to normal pressure, the wound film was rewound, and aged at 40°C for two days to produce a laminate with an Al (aluminum) vapor-deposited layer laminated on the film.

[0189] <Evaluation Method for Water Vapor Barrier Properties>

[0190] The water vapor transmission rate of the Al-deposited laminate was measured using a water vapor transmission rate measuring device "PERMATRAN-W" (registered trademark) 3 / 30 manufactured by MOCON / Modern Controls at a temperature of 40°C and a humidity of 90% RH. Five measurements were performed per sample, and the average of the obtained values ​​was calculated as the water vapor transmission rate of the film (unit: g / m 2 Based on the obtained water vapor transmission rate, the water vapor barrier properties of the laminate were evaluated according to the following criteria.

[0191] A:20 g / m 2 / day or less

[0192] B: than 20 g / m 2 / day, and 50 g / m 2 / day or less

[0193] C: 50 g / m 2 / day, and 75 g / m 2 / day or less

[0194] D: 75 g / m 2 / day and 100 g / m 2 / day or less

[0195] E: more than 100 g / m 2 / day

[0196] The barrier property of the film is preferably D or higher.

[0197] (17) Pinholes after bending test

[0198] In accordance with ASTM F-392, using a Gelbo tester with a thermostatic chamber manufactured by Tester Industrial Co., Ltd., 10 films, cut into 297 x 210 mm pieces, were subjected to 500 repetitions of a bending test at 10°C. The average number of pinholes was calculated. Content retention was evaluated according to the following criteria. The 10 test pieces were randomly cut, without specifying the direction of the main orientation axis or the direction perpendicular to the main orientation axis.

[0199] A: 0 or less than 3 pinholes were generated.

[0200] B: Three or more and less than five pinholes were generated.

[0201] C: 5 or more and less than 7 pinholes were generated.

[0202] D: 7 or more and less than 10 pinholes were generated.

[0203] E: More than 10 pinholes were generated.

[0204] The content protection of the film is preferably D or higher.

[0205] [Resin, etc.]

[0206] The following resins and the like were used to produce the polyhydroxyalkanoic acid films in the respective Examples and Comparative Examples.

[0207] (Polyhydroxyalkanoic acid resin)

[0208] A1: PHBH resin (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), crystal nucleating agent: pentaerythritol 1.0% by mass, weight average molecular weight Mw: 500,000, melting point: 153°C)

[0209] A2: PHBH resin (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), crystal nucleating agent: pentaerythritol 1.0% by mass, weight average molecular weight Mw: 600,000, melting point: 146°C)

[0210] A3: PHBH resin (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), crystal nucleating agent: behenamide 1.0% by mass, weight average molecular weight Mw: 500,000, melting point: 153°C)

[0211] A4: PHBH resin (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), crystal nucleating agent: talc 1.0% by mass, weight average molecular weight Mw: 500,000, melting point: 153°C)

[0212] A5: PHBH resin without nucleating agent (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), weight average molecular weight Mw: 500,000, melting point: 153°C)

[0213] A6: PHBV resin (poly(3-hydroxybutyrate-co-3-hydroxyvalerate), crystal nucleating agent: pentaerythritol 1.0% by mass, weight average molecular weight Mw: 450,000, melting point: 170°C)

[0214] (Example 1)

[0215] The polyhydroxyalkanoic acid resin raw material (A1) was supplied to a single-screw melt extruder. The oxygen concentration in the extruder feed hopper was controlled to 0.05% by volume. Melt extrusion was performed in each extruder at 170°C. Foreign matter was removed from the extruded molten resin using a 250μm cutoff mesh filter. The extruded molten resin was then guided to a T-die and discharged as a sheet. The discharged molten sheet was cooled and solidified on a casting drum maintained at 30°C to obtain an unstretched sheet.

[0216] Next, the unstretched sheet was directed to the MD stretching stage while the film forming speed draw ratio was multiplied by 108% during the section where it entered the casting drum and the machine direction (MD) stretching stage. In the MD stretching stage, the sheet was held at 30°C for 100 seconds on a set of rollers, then held at 152°C for 1 second. The sheet was then stretched 3.5 times in the machine direction by passing between rollers maintained at 152°C with a peripheral speed differential. The stretched film was then cooled by passing between rollers maintained at 30°C and then to room temperature to obtain a uniaxially oriented film. The resulting uniaxially oriented film was then directed to a tenter frame, preheated to 100°C while being gripped at both ends in the width direction with clips. After being stretched to 2.4 times in the width direction at 100°C, the film was then subjected to a 5% relaxation at a rate of 40% / min at 120°C in the width direction and heat treated at 120°C for 15 seconds. Then, while continuing to tightly hold both ends in the width direction with clips, the film is guided to the outside of the tenter after a cooling process at 50°C, the clips at both ends in the width direction are released, corona treatment is performed on one surface, and then the polyhydroxyalkanoic acid film with a thickness of 20 μm is taken down as a roll using a winder.

[0217] Next, the polyhydroxyalkanoic acid film was unwound from the roll, and Al was vapor-deposited on the surface subjected to the corona discharge treatment by the above-mentioned method to obtain a laminate having an Al vapor-deposited layer (D layer).

[0218] (Examples 2 to 6, 10 to 15)

[0219] A polyhydroxyalkanoic acid film and a laminate were produced in the same manner as in Example 1 except that the production conditions were changed to those shown in the table.

[0220] (Example 7)

[0221] A polyhydroxyalkanoic acid film and a laminate were produced in the same manner as in Example 1, except that A2 was used as the polyhydroxyalkanoic acid resin and the film formation conditions were changed to those shown in the table.

[0222] (Example 8)

[0223] A polyhydroxyalkanoic acid film and a laminate were prepared in the same manner as in Example 1, except that A3 was used as the polyhydroxyalkanoic acid resin and the film formation conditions were changed to those shown in the table.

[0224] (Example 9)

[0225] A polyhydroxyalkanoic acid film and a laminate were produced in the same manner as in Example 1 except that A6 was used as the polyhydroxyalkanoic acid resin, the extruder temperature was changed to 190° C., and the film forming conditions were changed to those shown in the table.

[0226] (Comparative Example 1)

[0227] A polyhydroxyalkanoic acid resin raw material (A1) was supplied to a single-screw melt extruder and melt-extruded at 170°C. After this, foreign matter was removed from the extruded molten resin using a 250μm cutoff mesh filter. Subsequently, the extruded molten resin was formed using a blow molding machine with a 60mm diameter circular die at a molding temperature of 150°C and a blow-up ratio of 2.5. After corona treatment, the blown polyhydroxyalkanoic acid film, 20μm thick, was wound into a roll using a winder. The polyhydroxyalkanoic acid film was then unwound from the roll, and Al was vapor-deposited on the corona-treated surface using the aforementioned method to produce a laminate having an Al vapor-deposited layer (layer D).

[0228] (Comparative Example 2)

[0229] A 60 μm-thick unstretched polyhydroxyalkanoic acid film and a laminate were produced in the same manner as in Example 1 except that biaxial stretching and heat treatment were not performed.

[0230] (Comparative Example 3)

[0231] A 40 μm thick polyhydroxyalkanoic acid film and laminate were prepared in the same manner as in Example 1 except that the oxygen concentration in the extruder supply hopper was controlled to 0.15 vol % and the longitudinal and transverse stretching ratios and heat treatment temperatures were changed to the conditions shown in the table.

[0232] (Comparative Example 4)

[0233] A polyhydroxyalkanoic acid film and a laminate were prepared in the same manner as in Example 1, except that A4 was used as the polyhydroxyalkanoic acid resin and the film formation conditions were changed to those shown in the table.

[0234] (Comparative Example 5)

[0235] A polyhydroxyalkanoic acid film was obtained in the same manner as in Example 1 except that A5 containing no nucleating agent was used as the polyhydroxyalkanoic acid resin and the film formation conditions were changed to those shown in the table. However, the film was cracked during the stretching step and no film could be obtained.

[0236] (Comparative Example 6)

[0237] A polyhydroxyalkanoic acid film and a laminate having a thickness of 25 μm were produced in the same manner as in Example 1, except that the stretching direction was set to be only MD and the film forming conditions were changed to those shown in the table.

[0238] (Comparative Example 7)

[0239] The polyhydroxyalkanoic acid film and laminate were prepared in the same manner as in Example 1 except that the film transport speed at the longitudinal stretching inlet relative to the casting outlet was controlled to 100% and other film forming conditions were changed to those shown in the table.

[0240] . .

[0241] .

[0242] .

[0243] .

[0244] .

[0245] . .

[0246] . .

[0247] .

[0248] Industrial availability

[0249] The present invention provides a polyhydroxyalkanoic acid film having both excellent biodegradability and excellent puncture strength. Due to the aforementioned properties, the polyhydroxyalkanoic acid film of the present invention exhibits excellent biodegradability, content protection, and barrier properties, and is therefore well suited for packaging applications or agricultural, forestry, and fishery applications.

[0250] Description of the accompanying drawings

[0251] 1: Diffraction image

[0252] 2: X-ray source

[0253] 3: Sample

[0254] 4: Thickness direction

[0255] 5: Main orientation axis direction

[0256] 6: Scan range

[0257] 7: Diffraction angle 2θ

[0258] 8: Direction perpendicular to the main orientation axis

[0259] 9: Elevation

Claims

1. A polyhydroxyalkanoic acid film having a puncture strength of 80 gf or more as determined by the following measuring apparatus and measuring conditions, wherein the puncture strength is a value calculated based on a thickness of 20 μm. Measuring device: KATOTECH's HANDY-TYPE COMPRESSION TESTERKES-G5 small compression tester Measurement conditions: Sensitivity: 10 Speed: 0.20 cm / s Stroke: 20mm / 10V Needle diameter: 1.0mm Aperture: 10.0mm .

2. The polyhydroxyalkanoic acid film according to claim 1, wherein the breaking strength in the main orientation axis direction is denoted as S1, and the breaking strength in the direction perpendicular to the main orientation axis direction is denoted as S2, S1 and S2 satisfy equations (1) and (2), wherein the units of S1 and S2 are both MPa, 30MPa≤S1≤280MPa Formula (1) 30MPa≤S2≤280MPa Formula (2).

3. The polyhydroxyalkanoic acid film according to claim 1 or 2, wherein in a thermal shrinkage curve obtained by a thermomechanical analyzer (TMA), the shrinkage start temperature T1 in the main orientation axis direction of the film and the shrinkage start temperature T2 in the direction perpendicular to the main orientation axis direction are both above 40°C and below 150°C, wherein the units of T1 and T2 are both °C.

4. The polyhydroxyalkanoic acid film according to claim 1 or 2, wherein the refractive index at a wavelength of 1550 nm in the direction of the main orientation axis is denoted as N1, and the refractive index at a wavelength of 1550 nm in a direction perpendicular to the main orientation axis is denoted as N2, and N1 and N2 satisfy the formula (3): 2.0×10 -4 ≤|N1 - N2|≤1.3×10 -2 Equation (3).

5. The polyhydroxyalkanoic acid film according to claim 1 or 2, wherein the thermal shrinkage H1 in the main orientation axis direction of the film and the thermal shrinkage H2 in the direction perpendicular to the main orientation axis direction, obtained by heat treatment at 120° C. for 15 minutes, are both greater than 0% and less than 20%, wherein the units of H1 and H2 are both %.

6. The polyhydroxyalkanoic acid film according to claim 1 or 2, wherein the elongation at break in the main orientation axis direction is denoted as L1, and the elongation at break in the direction perpendicular to the main orientation axis direction is denoted as L2, L1 and L2 are both greater than 10% and less than 350%, wherein the units of L1 and L2 are both %.

7. The polyhydroxyalkanoic acid membrane according to claim 1 or 2, wherein the puncture displacement determined by the following measuring apparatus and measuring conditions is 2.0 mm or more and 4.5 mm or less. Measuring device: KATOTECH's HANDY-TYPE COMPRESSION TESTERKES-G5 small compression tester Measurement conditions: Sensitivity: 10 Speed: 0.20 cm / s Stroke: 20mm / 10V Needle diameter: 1.0mm Aperture: 10.0mm .

8. The polyhydroxyalkanoic acid film according to claim 1 or 2, wherein the refractive index at a wavelength of 1550 nm in the main orientation axis direction is represented by N1, the refractive index at a wavelength of 1550 nm in a direction perpendicular to the main orientation axis direction is represented by N2, the refractive index at a wavelength of 1550 nm in the thickness direction is represented by Nz, and the average value of N1 and N2 is represented by N12, satisfies formula (4): 0.002≤(N12 - Nz)≤0.015 Formula (4).

9. The polyhydroxyalkanoic acid film as described in claim 1 or 2, in wide-angle X-ray diffraction in the thickness direction using CuKα rays, when the peak with the highest intensity among the peaks with an orientation degree of 0.50 or more in the range of diffraction angle 2θ of 19° or more and 21° or less is recorded as PB, the crystallite size calculated based on the half-peak width of PB is 5 nm or more and 60 nm or less.

10. The polyhydroxyalkanoic acid film according to claim 1 or 2, further comprising a functional layer on at least one side thereof.

11. The polyhydroxyalkanoic acid film according to claim 1 or 2, which is used for packaging purposes.

12. A package comprising the polyhydroxyalkanoic acid film according to claim 1 or 2.

13. The polyhydroxyalkanoic acid membrane according to claim 1 or 2, which is used in agriculture, forestry, and fisheries.

14. An agricultural, forestry, and fishery material comprising the polyhydroxyalkanoic acid membrane according to claim 1 or 2.

15. A biodegradation method comprising decomposing the polyhydroxyalkanoic acid film according to claim 1 or 2 using composting equipment.

16. A biodegradation method comprising decomposing the package according to claim 12 using composting equipment.

17. A biodegradation method comprising decomposing the agricultural, forestry, and fishery materials according to claim 14 using composting equipment.

18. The polyhydroxyalkanoic acid film according to claim 1 or 2, which is a film for coating agricultural, forestry, and fishery raw materials containing one or more selected from fertilizers, feeds, seeds, and chemicals.

19. An agricultural, forestry and aquatic raw material, characterized in that: Coated with the polyhydroxyalkanoic acid film according to claim 1 or 2.

Images