Resin composition for calendar molding, calendar molding film, and method for producing the same

Abstract

To provide a resin composition for calendaring that contains a poly (3-hydroxy butylate) resin and is suitable for producing a film by calendering.SOLUTION: A resin composition for calendaring contains: a poly (3-hydroxy butylate) resin (A) with a degree of dispersion (Mw / Mn) of 2.09 or less; and a poly (3-hydroxy butylate) resin (B) with a degree of dispersion of 2.10 or more. The total of poly (3-hydroxy butylate) resins have a weight average molecular weight of 400,000 or more and a degree of dispersion of 2.10 or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition for calendering containing a poly(3-hydroxybutyrate) - based resin, a calendered film, and a method for producing the same.

Background Art

[0002] In recent years, environmental problems caused by waste plastics have been spotlighted. In particular, it has been found that plastics that have been discarded into the ocean, especially those that have flowed into the sea via ocean dumping or rivers, are floating in large quantities in the ocean on a global scale. Since such plastics maintain their shape over a long period of time, they are pointed out to have an impact on the ecosystem, such as so-called ghost fishing that restrains and captures marine organisms, and when ingested by marine organisms, they remain in the digestive tract and cause feeding disorders.

[0003] Furthermore, it has also been pointed out that microplastics formed by the disintegration and atomization of plastics by ultraviolet rays and the like adsorb harmful compounds in seawater, and when marine organisms ingest these, harmful substances are incorporated into the food chain.

[0004] In response to such marine pollution caused by plastics, the use of biodegradable plastics is expected. However, in a report compiled by the United Nations Environment Programme in 2015, it is pointed out that plastics that are biodegradable in compost, such as polylactic acid, cannot be expected to decompose in a short period of time in the actual ocean where the temperature is low, and thus cannot be a countermeasure against marine pollution.

[0005] Under such circumstances, poly(3-hydroxybutyrate) - based resins are attracting attention as materials to solve the above problems because they can undergo biodegradation even in seawater.

[0006] Patent Document 1 describes a polyester resin composition containing two types of polyhydroxyalkanoates. Examples of its molded products include films and sheets, and it is described that a sheet with a thickness of 100 μm was produced.

[0007] In Patent Document 2, a thermoplastic resin mainly composed of polyhydroxyalkanoate is melted and formed into a film, crystallized, and then rolled at a temperature below the melting point and above the glass transition temperature of the resin for primary stretching, and further secondary stretching is performed at a temperature higher than the rolling temperature to produce a film.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] As one of the film forming methods, the calendar forming method is known. The calendar forming method refers to a technique of forming a film by sandwiching a resin raw material heated to a molten state in advance between a plurality of rolls and rolling it. When the present inventors tried to produce a film using a poly(3-hydroxybutyrate)-based resin as a constituent resin by the calendar forming method, they found that depending on the state of the poly(3-hydroxybutyrate)-based resin as a raw material, film formation by calendar forming may become difficult.

[0010] In view of the above situation, an object of the present invention is to provide a resin composition for calendar forming that contains a poly(3-hydroxybutyrate)-based resin and is suitable for producing a film by calendar forming.

Means for Solving the Problems

[0011] As a result of intensive studies to solve the above problems, the present inventors have found that a resin composition using two types of poly(3-hydroxybutyrate) resins having different degrees of dispersion and setting the weight average molecular weight and the degree of dispersion of the entire poly(3-hydroxybutyrate) resin to be not less than specific values can realize the production of a film by calender molding, and thus have completed the present invention.

[0012] That is, the present invention relates to a resin composition for calender molding, which contains a poly(3-hydroxybutyrate) resin (A) having a degree of dispersion (Mw / Mn) of 2.09 or less and a poly(3-hydroxybutyrate) resin (B) having a degree of dispersion of 2.10 or more, wherein the weight average molecular weight of the entire poly(3-hydroxybutyrate) resin is 400,000 or more and the degree of dispersion is 2.10 or more. Preferably, the weight average molecular weight of the poly(3-hydroxybutyrate) resin (A) is 400,000 or more. Preferably, the weight average molecular weight of the poly(3-hydroxybutyrate) resin (B) is 400,000 or more and is not more than the weight average molecular weight of the poly(3-hydroxybutyrate) resin (A). Preferably, the poly(3-hydroxybutyrate) resin (B) is a calender molded product. Preferably, the melt viscosity of the resin composition for calender molding is 2800 or more and 3500 poise or less. Preferably, the resin composition for calender molding further contains a filler (C). Preferably, the filler (C) is at least one selected from the group consisting of talc, silica, mica, kaolinite, montmorillonite, and smectite. Preferably, the content of the filler (C) is 0.01 to 20 parts by weight with respect to 100 parts by weight of the total amount of the poly(3-hydroxybutyrate) resin. Preferably, the melt viscosity of the resin composition for calender molding is 2800 or more and 4700 poise or less. The present invention also relates to a calender molded film containing the resin composition for calender molding. Preferably, the heat shrinkage rate of the film is 8% or more. Furthermore, the present invention relates to a method for manufacturing a calendared film, which includes a step of kneading a film raw material containing a poly(3-hydroxybutyrate) resin (A) with a dispersity (Mw / Mn) of 2.09 or less and a poly(3-hydroxybutyrate) resin (B) with a dispersity of 2.10 or more using a hot roll to obtain a resin composition for calendaring in which the weight average molecular weight of the entire poly(3-hydroxybutyrate) resin is 400,000 or more and the dispersity is 2.10 or more, and a step of rolling the resin composition for calendaring with a plurality of calendar rolls to obtain a calendared film. Preferably, the manufacturing method further includes a step of stretching the calendared film in the MD direction. Preferably, the stretching ratio in the step of stretching in the MD direction is 1.5 to 1.7 times. Preferably, the manufacturing method further includes a step of stretching the calendared film in the TD direction. Preferably, the stretching ratio in the step of stretching in the TD direction is 1.5 to 1.7 times. Preferably, the manufacturing method further includes a step of cutting out a part of the calendared film to obtain an end material. Preferably, the end material is supplied as the poly(3-hydroxybutyrate) resin (B) in the step of obtaining the resin composition for calendaring.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a resin composition for calendaring containing a poly(3-hydroxybutyrate) resin and suitable for manufacturing a film by calendaring. According to a preferred embodiment of the present invention, it is possible to recycle the end material generated by trimming the end of the calendared film and effectively use it as one kind of the film raw material to newly manufacture a calendared film. According to a preferred embodiment of the present invention, it is possible to manufacture a calendared film in which drawdown due to heating is suppressed and which can be processed into a thermoformed body having a relatively uniform wall thickness by thermoforming.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0016] This embodiment relates to a resin composition used for producing a resin film by calender molding, with a poly(3-hydroxybutyrate)-based resin as the constituent resin. The poly(3-hydroxybutyrate)-based resin is an aliphatic polyester resin that can be produced from microorganisms and is a polyester resin having 3-hydroxybutyrate as a repeating unit. The poly(3-hydroxybutyrate)-based resin may be poly(3-hydroxybutyrate) having only 3-hydroxybutyrate as a repeating unit, or a copolymer of 3-hydroxybutyrate and another hydroxyalkanoate. Further, the poly(3-hydroxybutyrate)-based resin may be a mixture of a homopolymer and one or more copolymers, or a mixture of two or more copolymers.

[0017] Specific examples of the poly(3-hydroxybutyrate) resin include poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), and the like. Among them, poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) are preferred because they are industrially easy to produce.

[0018] Furthermore, by changing the composition ratio of the repeating units, the melting point and crystallinity can be changed, and physical properties such as Young's modulus and heat resistance can be changed, and it is possible to impart physical properties between polypropylene and polyethylene. Also, from the viewpoint of being industrially easy to produce and being a physically useful plastic, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is preferred. In particular, among the poly(3-hydroxybutyrate) resins having the property of being easily thermally decomposed under heating at 180 °C or higher, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is preferred also from the viewpoint that it can lower the melting point and enables molding processing at a low temperature.

[0019] From the viewpoint of the balance between flexibility and strength, the composition ratio of the repeating units of the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is preferably such that the composition ratio of the 3-hydroxybutyrate unit / 3-hydroxyhexanoate unit is 80 / 20 to 99 / 1 (mol / mol), and more preferably 75 / 15 to 97 / 3 (mol / mol). The reason is that less than 99 / 1 is preferred from the viewpoint of flexibility, and 80 / 20 or more is preferred in that the resin has appropriate hardness.

[0020] Examples of commercially available poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) include "Kaneka Biodegradable Polymer PHBH" (registered trademark) of Kaneka Corporation.

[0021] The melting point, Young's modulus, etc. of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) vary depending on the ratio of the 3-hydroxybutyrate component and the 3-hydroxyvalerate component. However, since both components co-crystallize, the degree of crystallinity is as high as 50% or more. Compared with poly(3-hydroxybutyrate), it is flexible, but the improvement of brittleness is insufficient.

[0022] The resin composition for calendar molding according to this embodiment uses at least two types of poly(3-hydroxybutyrate) - based resins having different dispersity (Mw / Mn). The poly(3-hydroxybutyrate) - based resin (A) with a relatively small dispersity has a dispersity of 2.09 or less, and the poly(3-hydroxybutyrate) - based resin (B) with a relatively large dispersity has a dispersity of 2.10 or more.

[0023] The poly(3-hydroxybutyrate) - based resin (A) is not particularly limited as long as its dispersity is 2.09 or less, and it can be any of the various poly(3-hydroxybutyrate) - based resins described above. Among them, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is preferably used.

[0024] The dispersity of the poly(3-hydroxybutyrate) - based resin (A) is 2.09 or less, preferably 2.08 or less. Such a poly(3-hydroxybutyrate) - based resin with a relatively small dispersity is usually produced and isolated by microorganisms and has not yet had a history of melt processing. The lower limit of the dispersity of the poly(3-hydroxybutyrate) - based resin (A) is not particularly limited, but is preferably 1.70 or more, more preferably 1.80 or more, still more preferably 1.90 or more, and particularly preferably 2.00 or more.

[0025] The weight average molecular weight of the poly(3-hydroxybutyrate) resin (A) is not particularly limited, but from the viewpoint of calendar moldability, it is preferably 400,000 or more, more preferably 450,000 or more, still more preferably 500,000 or more, and particularly preferably 550,000 or more. The upper limit of the weight average molecular weight is not particularly limited, but from the viewpoint of resin productivity, it is preferably 1,000,000 or less, more preferably 800,000 or less, and still more preferably 700,000 or less.

[0026] Incidentally, as the poly(3-hydroxybutyrate) resin (A), only one type may be used, or two or more types may be used in combination.

[0027] On the other hand, the poly(3-hydroxybutyrate) resin (B) is not particularly limited as long as its dispersity is 2.10 or more, and it can be any of the various poly(3-hydroxybutyrate) resins described above. Among them, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is preferable.

[0028] The dispersity of the poly(3-hydroxybutyrate) resin (B) is 2.10 or more, preferably 2.12 or more, and more preferably 2.14 or more. The poly(3-hydroxybutyrate) resin having a relatively large dispersity usually has a history of being subjected to melt processing one or more times. The upper limit of the dispersity of the poly(3-hydroxybutyrate) resin (B) is not particularly limited, but is preferably 2.50 or less, more preferably 2.40 or less, and still more preferably 2.35 or less.

[0029] The weight average molecular weight of the poly(3-hydroxybutyrate) resin (B) is not particularly limited, but it is preferably the same as or smaller than the weight average molecular weight of the poly(3-hydroxybutyrate) resin (A). Further, from the viewpoint of calendar moldability, the weight average molecular weight of the poly(3-hydroxybutyrate) resin (B) is preferably 400,000 or more, more preferably 450,000 or more, still more preferably 500,000 or more, and particularly preferably 550,000 or more. The upper limit of the weight average molecular weight is not particularly limited, but from the viewpoint of resin productivity, it is preferably 1,000,000 or less, more preferably 800,000 or less, and still more preferably 700,000 or less.

[0030] Incidentally, as the poly(3-hydroxybutyrate) resin (B), only one type may be used, or two or more types may be used in combination. The weight average molecular weight and dispersity of each of the poly(3-hydroxybutyrate) resin (A) and the poly(3-hydroxybutyrate) resin (B) are values measured in terms of polystyrene using gel permeation chromatography with a chloroform solution.

[0031] Generally, the molecular weight of the poly(3-hydroxybutyrate) resin tends to decrease and the dispersity tends to increase due to heating during melting. As the molecular weight of the resin decreases and the dispersity increases in this way, film formation by calendar molding using the resin tends to become difficult.

[0032] On the other hand, in calendar molding, in order to align the width of the film product, a step of trimming the ends after film formation is performed, whereby end materials may be generated. Further, even after thermoforming is performed on the obtained film and the thermoformed body is punched out, end materials (also referred to as skeletons) may be generated. Since a large amount of these end materials are generated, it is desired to recycle and reuse them as the raw material resin for calendar molding.

[0033] However, since the poly(3-hydroxybutyrate)-based resin contained in such edge materials has a low molecular weight and a large dispersity due to heating during melting as described above, it tends to be difficult to form a film even when it is reused as a raw material resin for calender molding. In particular, this difficulty becomes prominent in resins with an increased number of recycling cycles.

[0034] However, since the poly(3-hydroxybutyrate)-based resin (B) in the present embodiment has a large dispersity, in the present embodiment, the edge materials generated by calender molding can be used as the poly(3-hydroxybutyrate)-based resin (B). That is, according to the present embodiment, it becomes possible to recycle the edge materials generated by calender molding and effectively use the edge materials as part of the raw material resin to newly manufacture a calender molding film.

[0035] The ratio of the poly(3-hydroxybutyrate)-based resin (A) to the poly(3-hydroxybutyrate)-based resin (B) may be appropriately determined in consideration of the weight average molecular weight and dispersity of the entire poly(3-hydroxybutyrate)-based resin described below. However, on a weight basis, it is preferably 30 to 99:1 to 70 for resin (A):resin (B), more preferably 40 to 95:5 to 60, and even more preferably 50 to 90:10 to 50.

[0036] From the viewpoint of calender moldability, the weight average molecular weight and ratio of each of the resin (A) and the resin (B) are adjusted so that the weight average molecular weight of the entire poly(3-hydroxybutyrate)-based resin contained in the calender molding resin composition according to the present embodiment is controlled to be 400,000 or more. When the weight average molecular weight is less than 400,000, it becomes difficult to form a film by calender molding. The molecular weight is preferably 420,000 or more. The upper limit of the molecular weight is not particularly limited, but is preferably 1,000,000 or less, more preferably 800,000 or less, and even more preferably 700,000 or less.

[0037] The resin composition for calendar molding according to this embodiment contains at least two types of poly(3-hydroxybutyrate) resins with different degrees of dispersion. Therefore, the degree of dispersion (Mw / Mn) of the poly(3-hydroxybutyrate) resins contained in the resin composition for calendar molding tends to be large, specifically 2.10 or more. It is preferably 2.15 or more, more preferably 2.20 or more. The upper limit of the degree of dispersion is not particularly limited, but it is preferably 2.80 or less, more preferably 2.70 or less, and even more preferably 2.60 or less.

[0038] The weight average molecular weight and the degree of dispersion of the poly(3-hydroxybutyrate) resins contained in the above resin composition for calendar molding as a whole are measured in a state where resin (A) and resin (B) are melt-kneaded to form a uniform composition. It may also be measured after melting resin (A) and resin (B) and then forming a film by calendar molding. The weight average molecular weight and the degree of dispersion are values measured by gel permeation chromatography using a chloroform solution and converted to polystyrene equivalents.

[0039] In this embodiment, since it has excellent thermoformability, the difference between the melting point peak temperature and the end temperature on the high-temperature side of the melting point peak in the differential scanning calorimetry measured for the poly(3-hydroxybutyrate) resins contained in the resin composition for calendar molding as a whole is preferably 10°C or more and 70°C or less. When the temperature difference is 10°C or more, when the poly(3-hydroxybutyrate) resin is melted, it becomes easy to leave a part of the crystals without melting. As a result, when thermoforming the calendar molding film, while performing sufficient preheating to mold the film, a uniform elongation can be realized during molding due to the tension held by the remaining crystals. Therefore, it becomes easy to provide a molded body with a relatively uniform thickness by thermoforming the film.

[0040] The temperature difference is more preferably 12 °C or higher, still more preferably 15 °C or higher, and even more preferably 18 °C or higher. The upper limit of the temperature difference is 70 °C or lower, and from the viewpoint of ease of production of the poly(3-hydroxybutyrate) resin, it is preferably 50 °C or lower, more preferably 40 °C or lower, still more preferably 35 °C or lower, and even more preferably 30 °C or lower.

[0041] The melting point peak temperature and the end temperature on the high-temperature side of the melting point peak in differential scanning calorimetry are measured as follows. 4 to 10 mg of a resin sample is filled into an aluminum pan, and using a differential scanning calorimeter, under a nitrogen stream, the temperature is raised from 30 °C to 180 °C at a rate of 10 °C / min to melt the resin sample. In the endothermic curve obtained at this time, the temperature at which the endothermic amount becomes maximum is defined as the melting point peak temperature, and the temperature at which the melting point peak ends on the high-temperature side of the melting point peak temperature and no endotherm is observed is defined as the end temperature on the high-temperature side of the melting point peak. The melting point peak temperature and the end temperature on the high-temperature side of the melting point peak are measured for the entire poly(3-hydroxybutyrate) resin contained in the resin composition for calendar molding.

[0042] As the poly(3-hydroxybutyrate) resin in which the temperature difference between the melting point peak temperature and the end temperature on the high-temperature side of the melting point peak is 10 °C or higher, a poly(3-hydroxybutyrate) resin having a broad melting point peak and containing a high melting point component can be used. Further, a combination of a poly(3-hydroxybutyrate) resin having a broad melting point peak and containing a high melting point component and another poly(3-hydroxybutyrate) resin having different melting point characteristics from the resin can also be used.

[0043] A specific production method of the poly(3-hydroxybutyrate) resin having a broad melting point peak and containing a high melting point component is described, for example, in International Publication No. 2015 / 146194.

[0044] The resin composition for calendar molding according to this embodiment preferably has a melt viscosity of 2,800 or more and 3,500 poise or less because the calendar molding becomes easy. The melt viscosity was measured by charging 7 g of a sample into a barrel with an inner diameter of 9.55 mm and a total length of 350 mm using a capillary rheometer (PMD-C, Toyo Seiki Co., Ltd.) based on the JIS K 7199 standard, heating it at 165° C. for 5 minutes, and detecting the force required to extrude the resin from the barrel into a capillary with a diameter of 1 mm and a length of 10 mm at an extrusion rate of 100 mm / min.

[0045] The resin composition for calendar molding according to this embodiment may or may not contain a filler (C). By containing the filler (C), the strength of the resulting calendar molding film can be increased.

[0046] The filler (C) may be either an inorganic filler or an organic filler, or both may be used in combination. The inorganic filler is not particularly limited, and examples thereof include silicates, carbonates, sulfates, phosphates, oxides, hydroxides, nitrides, carbon black, and the like. Only one type of filler may be used, or two or more types may be used in combination. As the filler (C), one or more selected from the group consisting of talc, silica, mica, kaolinite, montmorillonite, and smectite are preferable.

[0047] The content of the filler (C) is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, and even more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the total amount of the poly(3-hydroxybutyrate) - based resin.

[0048] When the resin composition for calendar molding according to this embodiment contains the filler (C), since the calendar molding becomes easy, the melt viscosity of the resin composition for calendar molding is preferably 2,800 or more and 4,700 poise or less.

[0049] In the resin composition for calendar molding, other resins other than poly(3-hydroxybutyrate)-based resins may be included as long as the effects of the invention are not impaired. Examples of such other resins include aliphatic polyester-based resins such as polybutylene succinate adipate, polybutylene succinate, polycaprolactone, and polylactic acid, and aliphatic aromatic polyester-based resins such as polybutylene adipate terephthalate, polybutylene sebacate terephthalate, and polybutylene azelate terephthalate. Only one kind of other resin may be included, or two or more kinds may be included.

[0050] The content of the other resin is not particularly limited, but is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 10 parts by weight or less with respect to 100 parts by weight of the total amount of the poly(3-hydroxybutyrate)-based resin. The lower limit of the content of the other resin is not particularly limited and may be 0 parts by weight or more.

[0051] Further, the resin composition for calendar molding preferably does not contain an additive that bleeds out when the resin composition or its molded body is stored at 80°C or higher. Although it has been found that a sample with pentaerythritol added in International Publication No. 2015 / 052876 does not bleed out after being stored at 23°C and a humidity of 50% or less for one month, there is a possibility of bleeding out under storage conditions of 80°C or higher. Therefore, the resin composition for calendar molding preferably does not contain pentaerythritol. Also, even without containing a nucleating agent such as pentaerythritol, by adopting the production method described later, a calendar molding film can be produced with good productivity.

[0052] Further, the resin composition for calendar molding may contain additives that can be used together with the poly(3-hydroxybutyrate) - based resin, as long as the effects of the invention are not inhibited. Such additives include colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolites, fragrances such as vanillin and dextrin, plasticizers, antioxidants, anti - oxidants, weather resistance improvers, ultraviolet absorbers, crystal nucleating agents, lubricants, mold release agents, water - repellent agents, antibacterial agents, sliding property improvers, and the like. Only one kind of additive may be contained, or two or more kinds may be contained. The content of these additives can be appropriately set by those skilled in the art according to the purpose of use.

[0053] (Calendar - formed film) One aspect of the present embodiment relates to a resin film (hereinafter also referred to as a calendar - formed film) obtained by molding the resin composition for calendar molding into a film shape by calendar molding. The calendar - formed film can be suitably used for producing a molded article (such as a container) having a predetermined shape by thermoforming.

[0054] The thickness of the calendar - formed film according to the present embodiment is not particularly limited. However, from the viewpoints of facilitating uniform pre - heating when performing thermoforming, being able to manufacture a molded article having a relatively uniform wall thickness and good appearance, and also from the viewpoints of the rigidity and lightness of the obtained molded article, it is preferably 0.1 to 1 mm. When the thickness of the film is less than the above range, appearance defects such as wrinkles and surface roughness may occur in the molded article obtained by thermoforming. On the contrary, when it is thicker, it becomes difficult to perform sufficient pre - heating to the extent that shaping is possible, and at the same time, it becomes difficult to obtain a molded article having a relatively uniform wall thickness and good appearance. The thickness of the film is preferably 0.15 to 0.8 mm, and more preferably 0.20 to 0.6 mm.

[0055] Generally, thermoforming is carried out by fixing the film ends with clamps or pins, preheating and softening the film using a far-infrared heater or the like, and then causing the film to conform to a mold by means of vacuum or compressed air. In such thermoforming, if the preheating is insufficient, the film cannot conform well to the mold, resulting in a molded article with poor so-called moldability. However, when the tension of the softened resin decreases too much after sufficient preheating, when thermoforming a molded article such as a container having a deep recess, particularly in a portion where the film is greatly stretched, there are problems such as extremely thin portions locally occurring and the strength of the molded article being impaired as a result.

[0056] In order to impart excellent thermoformability, the calendar-formed film according to the present embodiment preferably has a heat shrinkage rate in the MD direction and / or TD direction of the film, measured by heating the film to 160 °C, of 8% or more. The heat shrinkage rate is a numerical value indicating the degree of shrinkage of the resin film when the resin film is heated. When the heat shrinkage rate is 8% or more, when the resin film is softened by heating, the shrinkage of the film suppresses drawdown, and it is possible to prevent the resin film from stretching too much and becoming non-uniform in thickness before shaping. Therefore, it becomes possible to form a molded article with a relatively uniform thickness. Note that a calendar-formed film satisfying the heat shrinkage rate can be manufactured by performing a stretching process as described later.

[0057] Generally, the MD direction is also called the machine direction, the flow direction, or the longitudinal direction, and the TD direction is a direction perpendicular to the MD direction, and is also called the perpendicular direction or the width direction. In the present embodiment, only the heat shrinkage rate in the MD direction may satisfy the numerical range, only the heat shrinkage rate in the TD direction may satisfy the numerical range, or the heat shrinkage rates in both the MD direction and the TD direction may satisfy the numerical range.

[0058] The heat shrinkage rate is preferably 10% or more, more preferably 12% or more. The upper limit of the heat shrinkage rate is not particularly limited, but from the viewpoint of ease of thermoforming, it is preferably 50% or less, more preferably 40% or less, still more preferably 30% or less, and particularly preferably 25% or less.

[0059] The heat shrinkage rate is measured as follows. As shown in FIG. 1, the calendered film is cut into a size of 120 mm in the MD direction × 120 mm in the TD direction, and a mark is made in a square shape of 100 mm in the MD direction × 100 mm in the TD direction at the center thereof. The film is placed on paper coated with silica, put into a dryer set at 160° C., heated for 10 minutes, cooled to room temperature, and then the length of the side of the square in the MD direction and / or TD direction is measured, and the heat shrinkage rate is obtained by Formula 1. Formula 1: Heat shrinkage rate = ((length before heating (mm)) - (length after heating (mm))) / (length before heating (mm)) × 100

[0060] The calendered film according to this embodiment preferably has a drawdown measured by the following method of 50 mm or less. Drawdown is a numerical value indicating the degree of the sag when the heated and softened film sags by its own weight. When the drawdown is 50 mm or less, it is possible to prevent the film from stretching too much and the thickness from becoming non-uniform from when the film is softened until it is shaped when thermoforming the film. Therefore, it is possible to form a molded body with a relatively uniform thickness. Note that a calendered film that satisfies the drawdown can be manufactured by performing a stretching step as described later.

[0061] The drawdown is more preferably 40 mm or less, still more preferably 30 mm or less, and particularly preferably 25 mm or less. The lower limit of the drawdown is not particularly limited, but from the viewpoint of ease of thermoforming, it is preferably 5 mm or more, more preferably 10 mm or more, and still more preferably 15 mm or more.

[0062] The drawdown is measured as follows. A thermograph is attached to the center of a resin film measuring 13 cm in the MD direction and 13 cm in the TD direction. The resin film is fixed to a frame table measuring 13 cm in length, 13 cm in width, and 20 cm in height, which has a square opening measuring 10 cm in length and 10 cm in width at the center. The frame table is placed in an oven set at 160°C, and when the thermograph indicates 120°C, the frame table is taken out. As shown in Figure 2, the vertical distance from the fixed surface of the resin film to the lowest point is defined as the drawdown. The lowest point refers to the lowest point when the resin film sags through the opening under its own weight due to softening by heating, as shown in Figure 2.

[0063] (Method for manufacturing a calendar-formed film) The calendar-formed film according to this embodiment can be manufactured, for example, by the following procedure. First, a film raw material containing a poly(3-hydroxybutyrate) resin (A) with a dispersity of 2.09 or less and a poly(3-hydroxybutyrate) resin (B) with a dispersity of 2.10 or more is melted by an extruder, and then the melted film raw material is kneaded by a hot roll to obtain a calendar-forming resin composition in which the weight average molecular weight of the entire poly(3-hydroxybutyrate) resin is 400,000 or more and the dispersity is 2.10 or more. Thereafter, the calendar-forming resin composition is rolled by a plurality of calendar rolls to obtain a calendar-formed film.

[0064] After rolling the calendar-forming resin composition with a calendar roll, the obtained film may be cooled on one or more cooling rolls, or may be cooled by sandwiching it between two cooling rolls.

[0065] Generally, poly(3-hydroxybutyrate) resins have an extremely slow crystallization rate compared to other crystalline resins such as polypropylene. Therefore, they tend not to be sufficiently crystallized and solidified on the surface of the cooling roll and are likely to adhere to the cooling roll. Therefore, the temperature control of the cooling roll is preferably 40 to 100°C for the purpose of allowing the crystallization of the poly(3-hydroxybutyrate) resin to proceed to some extent and avoiding adhesion to the cooling roll.

[0066] In the process of cooling the calendar-formed film or the like, the film is pulled in the MD direction by making a difference in the rotational speed between the rolls, and / or the width-direction ends of the film are clamped and pulled in the TD direction, thereby preferably performing a step of stretching the film in the MD direction and / or the TD direction. By performing the stretching step, when the obtained calendar-formed film is heated, the stretched molecular chains contract, and the entire film greatly contracts. Therefore, a calendar-formed film that satisfies the numerical range of the heat shrinkage rate described above can be obtained.

[0067] From the viewpoint of the heat shrinkage rate, the stretching ratio in the stretching step is preferably 1.5 to 1.7 times or more in the MD direction and / or the TD direction.

[0068] The step of forming the film and the stretching step are preferably continuously performed. Specifically, after performing the step of forming the film, it is preferable to perform the stretching step without performing a crystallization step (specifically, a step of quenching in ice water and then annealing at 40°C for 12 hours) as described in Patent Document 2.

[0069] In this embodiment, the poly(3-hydroxybutyrate)-based resin contained during the calendar forming before the stretching step is not completely crystallized. However, some crystals remain in the film without melting, and the crystals and the melt of the resin are mixed. By performing the stretching step on such a film, a calendar-formed film that satisfies the numerical range of the heat shrinkage rate described above can be obtained, and without performing the aforementioned complicated crystallization step, during and after the stretching step, starting from the remaining crystals, the crystallization of the entire poly(3-hydroxybutyrate)-based resin easily proceeds.

[0070] From the above viewpoints, it is preferable to set the manufacturing conditions so that the temperature of the film raw material containing the poly(3-hydroxybutyrate) resin and the film ranges from 40°C to 165°C from the melting of the film raw material by an extruder to the stretching and then obtaining a calendered film. When the temperature exceeds 165°C, crystals in the poly(3-hydroxybutyrate) resin cannot be retained during the manufacturing process. As a result, the crystallization of the entire poly(3-hydroxybutyrate) resin becomes difficult to progress, and the productivity of the calendered film may decrease. Also, when it is less than 40°C, film forming or stretching at a predetermined magnification may not be sufficiently carried out, or the obtained calendered film may not satisfy the numerical range of the heat shrinkage rate described above. The temperature is more preferably from 40°C to 165°C, and even more preferably from 60°C to 160°C.

[0071] In obtaining the final product of the calendered film, for example, a step of cutting out a part of the film may be carried out by trimming the side ends of the film or the like. The end material generated by this step can be reused as the poly(3-hydroxybutyrate) resin (B). That is, the end material can be supplied as a part of the film raw material to the above-described extruder (the extruder for melting the film raw material). Thereby, it becomes possible to effectively utilize the end material generated by calendering without discarding it.

[0072] (Thermoforming) The calendered film according to the present embodiment can be used for thermoforming into a molded body having concave portions and / or convex portions, such as a container. Thermoforming can be carried out, as described above, by preheating and softening the film and then conforming it to a mold using vacuum or compressed air. Specific examples of the thermoforming include methods such as vacuum forming, pressure air forming, vacuum-pressure air forming, matched mold forming, plug assist forming, and TOM forming. However, vacuum forming and pressure air forming are preferable because they are simple and the mold cost is low.

[0073] The temperature of the film achieved by the preliminary heating can be appropriately set by those skilled in the art, but it is preferably a temperature between the melting point peak temperature in the differential scanning calorimetry of the poly(3-hydroxybutyrate) resin and the end temperature on the high temperature side of the melting point peak. By preheating the film to such a temperature, most of the poly(3-hydroxybutyrate) resin is melted, and at the same time, some crystals remain without being melted. As a result, it is possible to achieve both sufficient preheating to an extent that enables shaping and uniform elongation due to the remaining crystals, and it becomes possible to manufacture a molded body with a relatively uniform thickness.

[0074] The apparatus used for preheating the calendered film to the above temperature is not particularly limited, and examples include a far-infrared heater, a heat ray heater, a warm air heater, etc. Among these, a far-infrared heater is preferred because it can be heated uniformly quickly. When using a far-infrared heater, generally, the temperature of the heater is set higher than the target film temperature, and the temperature of the film is controlled by the distance between the heater and the film and the preheating time. For example, a method of installing a far-infrared heater set at 300 to 350 °C at a distance of 10 to 50 cm from the film and heating for 5 to 30 seconds can be mentioned. The actual temperature of the film can be measured by a non-contact thermometer using infrared rays, or by attaching a thermo label (registered trademark) whose color changes with temperature to the film to set the preheating conditions.

[0075] The molded body obtained by thermoforming the calendered film according to this embodiment is not particularly limited, and examples include a container having a concave portion in the center, a container having a partition, a container having a folded-back portion around the opening, a lid, etc.

Examples

[0076] Examples and comparative examples are shown below to more specifically explain the present invention, but the present invention is not limited to these examples at all.

[0077] (Raw materials used) PHBH(A”): Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH) (powder form) obtained according to the method described in International Publication No. WO 2013 / 147139, with a 3-hydroxyhexanoate (3HH) composition of 11.0 mol% and a weight-average molecular weight of 610,000 in terms of standard polystyrene measured by GPC PHBH(B”): P3HB3HH (powder form) obtained according to the method described in International Publication No. WO 2008 / 010296, with a 3HH composition of 5.5 mol% and a weight-average molecular weight of 550,000 in terms of standard polystyrene measured by GPC PHBH(H”): P3HB3HH (powder form) obtained according to the method described in International Publication No. WO 2008 / 010296, with a 3HH composition of 4.6 mol% and a weight-average molecular weight of 210,000 in terms of standard polystyrene measured by GPC PHBH(I”): P3HB3HH (powder form) obtained according to the method described in International Publication No. WO 2008 / 010296, with a 3HH composition of 5.4 mol% and a weight-average molecular weight of 360,000 in terms of standard polystyrene measured by GPC PHBH(K”): P3HB3HH (powder form) obtained according to the method described in International Publication No. WO 2008 / 010296, with a 3HH composition of 5.6 mol% and a weight-average molecular weight of 380,000 in terms of standard polystyrene measured by GPC PHBH(L”): P3HB3HH (powder form) obtained according to the method described in International Publication No. WO 2008 / 010296, with a 3HH composition of 11.2 mol% and a weight-average molecular weight of 570,000 in terms of standard polystyrene measured by GPC

[0078] PHBH(C”): End material of the film obtained in Reference Example 1 using PHBH(A”) and PHBH(B”) PHBH(D”): End material of the film obtained in Example 1 using PHBH(A”), PHBH(B”) and PHBH(C”) PHBH(E”): End material of the film obtained in Example 2 using PHBH(A”), PHBH(B”) and PHBH(D”) End material of the film obtained in Example 3 using PHBH(F”) : PHBH(A”) and PHBH(B”) and PHBH(E”) End material of the film obtained in Example 4 using PHBH(G”) : PHBH(A”) and PHBH(B”) and PHBH(F”)

[0079] End material of the film obtained according to Reference Example 1 by adding 60 parts by weight of PHBH(A”), 25 parts by weight of PHBH(B”), and 15 parts by weight of filler (C) to PHBH(M) End material of the film obtained according to Reference Example 1 by adding 61 parts by weight of PHBH(A”), 24 parts by weight of PHBH(B”), and 15 parts by weight of filler (C) to PHBH(N) End material of the film obtained according to Reference Example 1 by adding 61 parts by weight of PHBH(A”), 24 parts by weight of PHBH(B”), and 15 parts by weight of filler (C) to PHBH(O) End material of the film obtained according to Reference Example 1 by adding 59 parts by weight of PHBH(A”), 26 parts by weight of PHBH(B”), and 15 parts by weight of filler (C) to PHBH(V)

[0080] Filler (C) : Micro Ace K-1 (manufactured by Nippon Talc Co., Ltd.)

[0081] (Measurement method of average molecular weight) The number average molecular weight and weight average molecular weight of the poly(3-hydroxybutyrate) - based resin were first measured as follows. The poly(3-hydroxybutyrate) - based resin to be measured was dissolved in chloroform and heated in a warm water bath at 60°C for 0.5 hours. The soluble component was filtered through a PTFE disposable filter with a pore size of 0.45 μm, and then GPC measurement was performed under the following conditions using the filtrate. Also, when measuring the number average molecular weight and weight average molecular weight of the entire resin, the resin film obtained in each Example or Comparative Example was used as the measurement object. GPC measurement device: RI monitor (L - 3000) manufactured by Hitachi, Ltd. Column: K - G (1 piece) and K - 806L (2 pieces) manufactured by Showa Denko KK Sample concentration: 3 mg / ml Eluent: Chloroform solution Eluent flow rate: 1.0 ml / min Sample injection volume: 100 μL Analysis time: 30 minutes Standard sample: Standard polystyrene

[0082] (Measurement method of melt viscosity) Based on JIS K 7199 standard, using a capillary rheometer (PMD-C, Toyo Seiki Co., Ltd.), after putting 7 g of sample into a barrel with an inner diameter of 9.55 mm and a total length of 350 mm, it was heated at 165 °C for 5 minutes, and the force to extrude the resin from the barrel into a capillary with a diameter of 1 mm × length of 10 mm at an extrusion speed of 100 mm / min was detected to measure the melt viscosity.

[0083] (Evaluation method of film appearance) The surface appearance of the resin films produced in each example and comparative example was evaluated according to the following criteria. 〇: There are 10 or fewer streaks (molding marks) of 10 cm or more per 1 m on the sheet surface. △: There are 11 - 30 streaks (molding marks) of 10 cm or more per 1 m on the sheet surface. ×: There are 31 or more streaks (molding marks) of 10 cm or more per 1 m on the sheet surface.

[0084] (Evaluation of heat shrinkage rate) As shown in Figure 1, the resin film was cut into a size of 120 mm in the MD direction × 120 mm in the TD direction, and a square mark with a size of 100 mm in the MD direction × 100 mm in the TD direction was made in the center. The resin film was placed on paper coated with silica, put into a dryer set at 160 °C, heated for 10 minutes, cooled to room temperature, and then the length of the side of the square in the MD direction was measured, and the heat shrinkage rate was obtained by Equation 1. Equation 1: Heat shrinkage rate = ((Length before heating (mm)) - (Length after heating (mm))) / (Length before heating (mm)) × 100

[0085] (Evaluation of drawdown property) A thermograph was attached to the center of a resin film measuring 13 cm in the MD direction and 13 cm in the TD direction. The resin film was fixed to a frame stand measuring 13 cm in length, 13 cm in width, and 20 cm in height, which had a square opening measuring 10 cm in length and 10 cm in width at the center. The frame stand was placed in an oven set at 160°C. When the thermograph indicated 120°C, the frame stand was taken out. As shown in Figure 2, the vertical distance from the fixed surface of the resin film to the lowest point was measured to evaluate the drawdown property.

[0086] <Reference Example 1> PHBH (A”) and PHBH (B”) were put into a planetary extruder at the compounding ratio (unit: parts by weight) described in Table 1. After melting and kneading at a set temperature of 140°C, the melted resin was rolled into a film using two rolls with a roll diameter of 60 cm, a roll width of 1400 cm, a roll set temperature of 120°C, and a roll rotation speed of 10 rpm. Then, the film was cooled while being stretched in the MD direction at a draw ratio of 1.5 to 1.7 times, and the widthwise ends were slit to obtain a resin film with a width of 1000 mm and a thickness of 0.3 mm. The feasibility of calendar forming and the film appearance were evaluated at this time. The molecular weight of the obtained resin film was measured by the above method, and the dispersity was calculated as the ratio of the weight average molecular weight to the number average molecular weight. Furthermore, the heat shrinkage rate and drawdown property of the obtained resin film were evaluated by the above method.

[0087] <Example 1> A resin film was obtained by calendar forming in the same manner as in Reference Example 1, except that PHBH (A”), PHBH (B”), and the edge material of the film obtained in Reference Example 1 (PHBH (C”)) were used at the compounding ratio described in Table 1. Molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 1.

[0088] <Example 2> A resin film was obtained by calendar forming in the same manner as in Reference Example 1, except that PHBH (A”), PHBH (B”), and the edge material of the film obtained in Example 1 (PHBH (D”)) were used at the compounding ratio described in Table 1. Molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 1.

[0089] <Example 3> A resin film was obtained by calendar molding in the same manner as in Reference Example 1, except that PHBH (A”), PHBH (B”), and the edge material of the film obtained in Example 2 (PHBH (E”)) were used at the compounding ratios shown in Table 1. Molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 1.

[0090] <Example 4> A resin film was obtained by calendar molding in the same manner as in Reference Example 1, except that PHBH (A”), PHBH (B”), and the edge material of the film obtained in Example 3 (PHBH (F”)) were used at the compounding ratios shown in Table 1. Molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 1.

[0091] <Example 5> A resin film was obtained by calendar molding in the same manner as in Reference Example 1, except that PHBH (A”), PHBH (B”), and the edge material of the film obtained in Example 4 (PHBH (G”)) were used at the compounding ratios shown in Table 1. Molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 1.

[0092] <Comparative Example 1> Attempts were made to perform calendar molding in the same manner as in Reference Example 1, except that only PHBH (H”) was used, but a resin film could not be obtained. A resin film was produced by T-die extrusion molding using the same material, and molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed on the resin film. The results are shown in Table 1.

[0093] <Comparative Example 2> Attempts were made to perform calendar molding in the same manner as in Reference Example 1, except that only PHBH (I”) was used, but a resin film could not be obtained. A resin film was produced by T-die extrusion molding using the same material, and molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed on the resin film. The results are shown in Table 1.

[0094] <Comparative Example 3> At the compounding ratios described in Table 1, except for using PHBH(K”) and PHBH(L”), calendar molding was attempted in the same manner as in Reference Example 1, but a resin film could not be obtained. Incidentally, a resin film was produced by T-die extrusion molding using the same materials, and molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed on the resin film. The results are shown in Table 1.

[0095]

Table 1

[0096] From Table 1, in Examples 1 to 5, resin films could be produced by calendar molding. The appearance of each resin film was good, the drawdown property due to heating was a relatively small value, and the thermoformability was excellent. On the other hand, in Comparative Examples 1 to 3, resin films could not be produced by calendar molding. Incidentally, in all of Comparative Examples 1 to 3, the weight average molecular weight of the entire resin was less than 400,000, and in addition, in Comparative Example 2, the dispersity of the entire resin was less than 2.10.

[0097] <Example 6> At the compounding ratios described in Table 2, PHBH(A”), PHBH(B”), and filler (C) were blended, melt-kneaded with PHBH(M), which is a film molded body, using a planetary extruder, and then a resin film was obtained by calendar molding in the same manner as in Reference Example 1, and molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 2.

[0098] <Example 7> At the compounding ratios described in Table 2, PHBH(A”), PHBH(B”), and filler (C) were blended, melt-kneaded with PHBH(N), which is a film molded body, using a planetary extruder, and then a resin film was obtained by calendar molding in the same manner as in Reference Example 1, and molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 2.

[0099] <Example 8> At the compounding ratios described in Table 2, PHBH (A”), PHBH (B”), and filler (C) were blended, and after melt-kneading with a planetary extruder with PHBH (O), which is a film molded body, a resin film was obtained by calendar molding in the same manner as in Reference Example 1, and molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 2.

[0100] <Example 9> At the compounding ratios described in Table 2, PHBH (A”), PHBH (B”), and filler (C) were blended, and after melt-kneading with a planetary extruder with PHBH (V), which is a film molded body, a resin film was obtained by calendar molding in the same manner as in Reference Example 1, and molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 2.

[0101] <Example 10> At the compounding ratios described in Table 2, PHBH (A”), PHBH (B”), and filler (C) were blended, and after melt-kneading with a planetary extruder with PHBH (V), which is a film molded body, a resin film was obtained by calendar molding in the same manner as in Reference Example 1, and molecular weight measurement, heat shrinkage rate, and drawdown property evaluation were performed. The results are shown in Table 2.

[0102]

Table 2

[0103] From Table 2, in Examples 6 to 10, a resin film could be produced by calendar molding. The appearance of each resin film was good. Also, in Examples 6 to 8, the drawdown property due to heating was a relatively small value, and the thermoformability was excellent.

Explanation of Symbols

[0104] 11 Frame base 12 Resin sheet hanging down from the opening of the frame base 13 Drawdown 14 Lowest point of the resin sheet

Claims

1. A poly(3-hydroxybutyrate) resin (A) having a dispersity (Mw / Mn) of 2.09 or less, and a poly(3-hydroxybutyrate) resin (B) having a dispersity of 2.10 or more, are contained, the weight average molecular weight of the entire poly(3-hydroxybutyrate) resin is 400,000 or more, and the dispersity is 2.10 or more, A resin composition for calender molding, wherein the weight average molecular weight of the poly(3-hydroxybutyrate) resin (A) and the weight average molecular weight of the poly(3-hydroxybutyrate) resin (B) are 400,000 or more.

2. The resin composition for calender molding according to claim 1, wherein the weight average molecular weight of the poly(3-hydroxybutyrate) resin (B) is equal to or less than the weight average molecular weight of the poly(3-hydroxybutyrate) resin (A).

3. The resin composition for calender molding according to claim 1 or 2, wherein the poly(3-hydroxybutyrate) resin (B) is a calender molded product.

4. The resin composition for calender molding according to any one of claims 1 to 3, wherein the melt viscosity of the resin composition for calender molding is 2800 or more and 3500 poise or less.

5. The resin composition for calender molding according to any one of claims 1 to 3, further containing a filler (C).

6. The resin composition for calender molding according to claim 5, wherein the filler (C) is one or more selected from the group consisting of talc, silica, mica, kaolinite, montmorillonite, and smectite.

7. The resin composition for calender molding according to claim 5 or 6, wherein the content of the filler (C) is 0.01 to 20 parts by weight with respect to 100 parts by weight of the total amount of the poly(3-hydroxybutyrate) resin.

8. The resin composition for calender molding according to any one of claims 5 to 7, wherein the melt viscosity of the resin composition for calender molding is 2800 or more and 4700 poise or less.

9. A calender molding film containing the resin composition for calender molding according to any one of claims 1 to 8.

10. The calender molding film according to claim 9, wherein the heat shrinkage rate of the film is 8% or more.

11. A method for manufacturing a calender molding film, comprising: A film raw material containing a poly(3-hydroxybutyrate) resin (A) with a dispersity (Mw / Mn) of 2.09 or less and a poly(3-hydroxybutyrate) resin (B) with a dispersity of 2.10 or more is kneaded by a hot roll to obtain a calendering resin composition in which the weight average molecular weight of the entire poly(3-hydroxybutyrate) resin is 400,000 or more and the dispersity is 2.10 or more, and a step of rolling the calendering resin composition with a plurality of calender rolls to obtain a calendered film, A method for producing a calendered film, wherein the weight average molecular weight of the poly(3-hydroxybutyrate) resin (A) and the weight average molecular weight of the poly(3-hydroxybutyrate) resin (B) are 400,000 or more.

12. The method for producing a calendered film according to claim 11, further comprising a step of stretching the calendered film in the MD direction.

13. The method for producing a calendered film according to claim 12, wherein the draw ratio in the step of stretching in the MD direction is 1.5 to 1.7 times.

14. The method for producing a calendered film according to any one of claims 11 to 13, further comprising a step of stretching the calendered film in the TD direction.

15. The method for producing a calendered film according to claim 14, wherein the draw ratio in the step of stretching in the TD direction is 1.5 to 1.7 times.

16. The method for producing a calendered film according to any one of claims 11 to 15, further comprising a step of cutting out a part of the calendered film to obtain an end material.

17. The method for producing a calendered film according to claim 16, wherein the end material is supplied as the poly(3-hydroxybutyrate) resin (B) in the step of obtaining the calendering resin composition.

Images