Biodegradable film and laminate

Abstract

The present invention provides: a biodegradable film that contains a polylactic acid and a phosphite ester compound, and with which device contamination during film formation is suppressed; and a laminate in which said biodegradable film is used. The present invention also provides a biodegradable film that contains a polylactic acid, and with which device contamination is suppressed while having at least a certain level of biodegradability.　The present invention provides a biodegradable film characterized by containing (A) a polylactic acid and (B) a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule. The present invention also provides a biodegradable film containing (A) a polylactic acid, (B) an aromatic phosphite ester compound having two or more phosphorus atoms in one molecule, and (C) an aliphatic phosphite ester compound having two or more phosphorus atoms in one molecule.

Description

Biodegradable films and laminates

[0001] This invention relates to biodegradable films and laminates.

[0002] Resin films are highly functional materials with excellent properties such as moisture resistance, water resistance, and oil resistance, as well as good mechanical strength. They are widely used in various applications, including packaging materials for food and pharmaceuticals, and protective films for displays.

[0003] On the other hand, in recent years, various problems have been raised, such as the increasing amount of plastic waste and concerns that the carbon dioxide generated by the incineration of plastic materials will contribute to global warming. For this reason, biodegradable biomass plastics have attracted considerable attention from the perspective of consideration for the global environment and human health, and the development of various materials combining conventional plastic materials with biomass plastics is actively underway (see, for example, Patent Documents 1 and 2).

[0004] Furthermore, Patent Document 3 discloses a marine biodegradable polyester resin composition, a molded article made therefrom, and a method for producing the same. Specifically, it is stated that by including a specific phosphite ester-based decomposition accelerator in a polyester resin composition (such as polylactic acid), the biodegradability is improved, and a marine biodegradable polyester resin composition that decomposes rapidly even in low-temperature seawater can be provided (Claim 1, paragraph

[0019] ). Note that the phosphite ester-based decomposition accelerator shown by general formula (I) in Patent Document 3 has two phosphorus atoms in one molecule, but does not have an aromatic ring in one molecule.

[0005] International Publication No. 2008 / 23758, JP 2017-519863, International Publication No. 2023 / 190104

[0006] Improving the biodegradability of biodegradable films obtained by forming biomass plastics (especially polylactic acid) is an important issue considering various applications. However, when a phosphite ester-based decomposition accelerator disclosed in Patent Document 3 is incorporated, there is a problem that equipment contamination occurs during film formation due to decomposition products (white powder) derived from the accelerator.

[0007] A first embodiment of the present invention has been made in view of the above, and aims to provide a biodegradable film containing polylactic acid and a phosphite ester compound, wherein contamination of the equipment during film formation is suppressed, and a laminate using the biodegradable film.

[0008] Furthermore, improving the biodegradability of biodegradable films obtained by forming biomass plastics (especially polylactic acid) is an important issue considering various applications. In the course of their research, the inventors discovered that when a phosphite ester-based decomposition accelerator (aliphatic phosphite ester compound) used in Patent Document 3 is incorporated, equipment contamination occurs during film formation due to decomposition products (white powder) derived from the aforementioned decomposition accelerator. On the other hand, further research revealed that while the use of aromatic phosphite ester compounds can suppress equipment contamination, it reduces biodegradability.

[0009] A second embodiment of the present invention aims to provide a biodegradable film containing polylactic acid that has a certain level of biodegradability while suppressing contamination of equipment.

[0010] As a first embodiment of the present invention, the inventors conducted extensive research to achieve the above objective and found that a biodegradable film containing polylactic acid and a specific phosphite ester compound can achieve the above objective, thus completing the present invention.

[0011] Furthermore, as a second embodiment of the present invention, the inventors conducted extensive research in view of the above findings and problems, and found that the above problems can be solved if the biodegradable film contains (A) polylactic acid, (B) an aromatic phosphite ester compound having two or more phosphorus atoms in one molecule, and (C) an aliphatic phosphite ester compound having two or more phosphorus atoms in one molecule. Based on this finding, the inventors conducted further research and completed the present invention.

[0012] In other words, the present invention encompasses, for example, the subject matter described in the following sections: 1. A biodegradable film characterized by containing (A) polylactic acid and (B) a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule. 2. The elongation at break A of the biodegradable film at the time of test specimen preparation, measured under the following measurement conditions (I). ０ The elongation at break A of the test specimen after 48 hours of constant temperature and humidity treatment, measured according to the following measurement conditions (II): ４８ Ratio A ４８ / A ０ The biodegradable film according to claim 1, wherein the ratio is 0.8 or less; <Measurement conditions (I)> A test piece (15 mm wide, 170 mm long) is cut from the biodegradable film and subjected to a tensile test using a Tensilon universal tester (Orientec Co., Ltd. "Model number RTG-1210") at a tensile speed of 200 mm / min and a chuck distance of 100 mm, and the elongation at break (%) is measured (A ０ ). <Measurement conditions (II)> The above test piece is cut separately from the same film, left to stand for 48 hours in a constant temperature and humidity chamber set to 60°C and 95% humidity, and then subjected to the above tensile test and the elongation at break (%) is measured (A ４８ ). However, under measurement condition (II), the elongation at break of the film that breaks before being subjected to the tensile test shall be 0%. 3. The biodegradable film according to item 1 or 2 above, wherein the phosphorus atom content in the biodegradable film is 0.01 mmol / g or more. 4. The biodegradable film according to any one of items 1 to 3 above, wherein the phosphite ester compound has two phosphite ester structures in one molecule. 5. The phosphite ester compound is given by the following formula (I-I); [However, R １ and R ２) is a hydrocarbon group having the same or different aromatic rings. ] A biodegradable film according to any one of items 1 to 4 above. 6. A biodegradable film according to any one of items 1 to 5 above, wherein the biodegradable film is a stretched film. 7. A laminate comprising a biodegradable film according to any one of items 1 to 6 above and a substrate. 8. A biodegradable film containing (A) polylactic acid, (B) an aromatic phosphite compound having two or more phosphorus atoms in one molecule, and (C) an aliphatic phosphite compound having two or more phosphorus atoms in one molecule. 9. The aromatic phosphite compound and the aliphatic phosphite compound are of formula (II-I): A biodegradable film according to claim 8, having a substructure shown by . 10. A biodegradable film according to claim 8 or 9, wherein the number of phosphorus atoms in the molecules of the aromatic phosphite compound and the aliphatic phosphite compound is 2 to 10. 11. A biodegradable film according to any one of claims 8 to 10, wherein the molecular weight of the aromatic phosphite compound and the aliphatic phosphite compound is 300 to 3000. 12. A biodegradable film according to any one of claims 8 to 11, wherein the content of the aromatic phosphite compound is 0.3 to 5.0 parts by mass per 100 parts by mass of the polylactic acid. 13. A biodegradable film according to any one of claims 8 to 12, wherein the content of the aliphatic phosphite compound is 0.01 to 0.5 parts by mass per 100 parts by mass of the polylactic acid. 14. A biodegradable film according to any one of claims 8 to 13, wherein the phosphorus atom content is 0.010 mmol / g or more. 15. A stretched film, a biodegradable film according to any one of claims 8 to 14. 16. A laminate comprising a biodegradable film according to any one of claims 8 to 15 and a substrate.

[0013] The biodegradable film of the first embodiment of the present invention is characterized by containing polylactic acid and a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule. In addition to improving the biodegradability of the film by containing the phosphite ester compound, contamination of the equipment during film formation is reduced.

[0014] According to a second embodiment of the present invention, it is possible to provide a biodegradable film that contains polylactic acid, has a certain level of biodegradability, and suppresses contamination of equipment.

[0015] The embodiments of the present invention will be described in detail below. In this specification, the expressions "containing" and "including" include the concepts of "containing," "including," "substantially consisting of," and "consisting only of."

[0016] In this specification, the "~" in numerical ranges means "greater than or equal to" and "less than or equal to." That is, the notation α~β means α or greater and β or less, or β or greater and α or less, and the range includes α and β.

[0017] Where upper and lower limits are stated separately in this specification, ranges formed by any combination of the stated upper and lower limits are also disclosed in this specification.

[0018] In specifying the inventions contained herein, the components (properties, structures, functions, etc.) described in each embodiment of this disclosure may be combined in any way. That is, this disclosure encompasses all subject matter consisting of any combination of the combinatable components described herein.

[0019] <First Embodiment> The biodegradable film of the first embodiment of the present invention is characterized by containing (A) polylactic acid and (B) a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule (hereinafter, in the scope describing the biodegradable film of the first embodiment of the present invention, also referred to as "the phosphite ester compound of the present invention"). Hereinafter, in the scope describing the biodegradable film of the first embodiment of the present invention, the biodegradable film of the first embodiment of the present invention will also be referred to as "the biodegradable film of the first embodiment" or "biodegradable film".

[0020] The biodegradable film of the first embodiment of the present invention having the above characteristics is characterized by containing polylactic acid and a phosphite compound having two or more phosphorus atoms and one or more aromatic rings in one molecule. By containing the phosphite compound, in addition to the improved biodegradability of the film, the contamination of the apparatus during film formation is reduced. The reason for this is considered to be that by adopting a specific phosphite compound, the heat resistance of the phosphite compound is high while ensuring the biodegradability (hydrolyzability) of polylactic acid, and the generation of decomposition products (white powder) derived from the phosphite compound during film formation is suppressed.

[0021] 1-1. Biodegradable film The biodegradable film of the first embodiment of the present invention contains polylactic acid and a phosphite compound having two or more phosphorus atoms and one or more aromatic rings in one molecule. Polylactic acid is a kind of biodegradable aliphatic polyester resin called "biomass plastic".

[0022] (Polylactic acid) Polylactic acid is not particularly limited, and for example, well-known polylactic acid such as polylactic acid obtained by polycondensing a lactic acid component as a raw material monomer can be widely used. Polylactic acid can contain only one of the optical isomers of L-lactic acid (L-form) and D-lactic acid (D-form), or both.

[0023] When polylactic acid has L-lactic acid (L-form) as the main component, the content ratio of the D-form can be, for example, 15.0 mol% or less, preferably 10.0 mol% or less, more preferably 8.0 mol% or less, still more preferably 7.0 mol% or less, even more preferably 6.0 mol% or less, and particularly preferably 5.0 mol% or less. Among these, it is more preferably 3.0 mol% or less, still more preferably 1.0 mol% or less, and most preferably 0.01 mol% or less. Also, the lower limit of the content ratio of the D-form is preferably as small as possible, and for example, it may be 0 mol%. When polylactic acid has D-lactic acid (D-form) as the main component, the content ratio of the L-form can be, for example, 15.0 mol% or less, preferably 10.0 mol% or less, more preferably 8.0 mol% or less, still more preferably 7.0 mol% or less, even more preferably 6.0 mol% or less, and particularly preferably 5.0 mol% or less. Among these, it is more preferably 3.0 mol% or less, still more preferably 1.0 mol% or less, and most preferably 0.01 mol% or less. Also, the lower limit of the content ratio of the L-form is preferably as small as possible, and for example, it may be 0 mol%. The glass transition temperature, crystallization temperature, molecular weight, etc. of the above polylactic acid are not particularly limited.

[0024] The melting point of polylactic acid is preferably 110°C to 200°C. When the melting point of polylactic acid is within the above range, it is easy to maintain good heat resistance and productivity of the resulting biodegradable film. Also, when the biodegradable film is a stretched film, it becomes easier to adjust the stretching ratio. The melting point of polylactic acid is preferably 120°C to 190°C, more preferably 130°C to 185°C, and still more preferably 140°C to 180°C.

[0025] The glass transition temperature of polylactic acid is not particularly limited, and for example, it can be -40°C to 70°C, and 0°C to 70°C is more preferable.

[0026] In this specification, the melting point and glass transition temperature of polylactic acid are values measured using a differential scanning calorimeter (for example, an input compensation type DSC, Diamond DSC manufactured by PerkinElmer).

[0027] The melt mass flow rate (MFR) of polylactic acid is not particularly limited. Preferably, the melt mass flow rate of polylactic acid is 0.5 g / 10 min to 15 g / 10 min, more preferably 1 g / 10 min to 10 g / 10 min, and even more preferably 2 g / 10 min to 10 g / 10 min, as this allows for a suitable resin fluidity and facilitates the production of the desired biodegradable film. In this specification, the melt mass flow rate refers to the value measured at 230°C and 21.18 N in accordance with JIS K-7210 (1999).

[0028] The method for producing polylactic acid is not particularly limited, and for example, known methods for producing polylactic acid can be widely adopted. In addition, commercially available polylactic acid can also be used. Representative commercially available polylactic acid products include NatureWorks' "4032D" (melting point 163°C), Total Corbion PLA's "L175" (melting point 175°C), "LX175" (melting point 155°C), and "LX930" (melting point 130°C).

[0029] (Phosphite Ester Compounds) The phosphite ester compounds of the present invention have two or more phosphorus atoms and one or more aromatic rings in one molecule. The phosphite ester compounds of the present invention act as decomposition accelerators that promote the hydrolysis (biodegradability) of polylactic acid in biodegradable films.

[0030] When a phosphite ester compound contains only one phosphorus atom per molecule, it is difficult or impossible to achieve the hydrolytic effect of polylactic acid. Furthermore, if the compound does not contain an aromatic ring per molecule, the heat resistance of the compound itself is low, and even if it can hydrolyze polylactic acid, equipment contamination occurs during film formation due to decomposition products (white powder) derived from the compound itself. The phosphite ester decomposition accelerator shown in Patent Document 3 by general formula (I) has two phosphorus atoms per molecule, but does not contain an aromatic ring per molecule, so the heat resistance of the decomposition accelerator is low, and equipment contamination is likely to occur. Therefore, it is essential that the phosphite ester compound of the present invention contains two or more phosphorus atoms and one or more aromatic rings per molecule.

[0031] The phosphite compound of the present invention only needs to have two or more phosphorus atoms and one or more aromatic rings in one molecule. Among them, those having two phosphite structures in one molecule are preferable, and those having two phosphite structures in one molecule and two or more aromatic rings in one molecule are more preferable. Such a phosphite compound of the present invention preferably has a molecular weight of about 500 to 1000, more preferably about 550 to 950, and still more preferably about 600 to 900 in terms of molecular weight.

[0032] Examples of the phosphite compound of the present invention include the following formula (I-I); [wherein, R １ and R ２ are hydrocarbon groups having the same or different aromatic rings.]. The phosphite compound represented by this is preferable. Here, the above-mentioned "hydrocarbon group having an aromatic ring" corresponding to R １ , R ２ is preferably a hydrocarbon group having 1 to 3 aromatic rings, and each aromatic ring may have any substituent.

[0033] Specific examples of the phosphite compound of the present invention include the following formula (I-II); Compound 1-1 represented by this can be mentioned. As a commercially available product, for example, "PEP-36" manufactured by ADEKA Corporation can be used for Compound 1-1.

[0034] Further, specific examples of the phosphite compound of the present invention include the following formula (I-III); Compound 1-2 represented by this can be mentioned. As a commercially available product, for example, "pentaerythritol bis(2,4-di-tert-butylphenyl phosphite), CAS: 26741-53-7" manufactured by Tokyo Chemical Industry Co., Ltd. can be used for Compound 1-2.

[0035] Further, specific examples of the phosphite compound of the present invention include the following formula (I-IV); Compounds 1-3, shown in the formula, are examples. Compounds 1-3 can be used as commercial products, for example, "3,9-Bis(2,4-dicumylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, CAS:154862-43-8" manufactured by Merck.

[0036] In the biodegradable film of the first embodiment of the present invention, the content of the phosphite ester compound of the present invention is not limited as long as the effect of promoting the biodegradability (hydrolysis) of polylactic acid and the effect of suppressing equipment contamination during film formation are obtained. However, from the viewpoint of phosphorus atom content, it is preferable that the phosphorus atom content in the biodegradable film of the first embodiment is 0.010 mmol / g or more. Among these, 0.020 mmol / g or more is more preferable, 0.025 mmol / g or more is even more preferable, and 0.030 mmol / g or more is particularly preferable. The upper limit of the phosphorus atom content in the biodegradable film of the first embodiment is not particularly limited, but for example, it is 0.150 mmol / g, 0.100 mmol / g, 0.080 mmol / g, 0.060 mmol / g, 0.050 mmol / g, or 0.045 mmol / g.

[0037] In the biodegradable film of the first embodiment of the present invention, the content of the phosphite ester compound of the present invention relative to the polylactic acid content is not limited, but for example, the content of the phosphite ester compound of the present invention per 100 parts by mass of polylactic acid is preferably 0.3 to 5.0 parts by mass, and more preferably 1.0 to 3.0 parts by mass.

[0038] (Resin components other than polylactic acid) The biodegradable film of the first embodiment of the present invention may contain resin components other than polylactic acid (hereinafter also referred to as "other resins"), to the extent that the effects of the present invention are not impaired. The types of other resins are not limited, but include known crystalline thermoplastic resins and known thermoplastic resins that can impart heat-sealability to biodegradable films.

[0039] In this specification, a crystalline thermoplastic resin is a thermoplastic resin in which a clear melting peak appears in the DSC curve when measured using a differential scanning calorimeter (e.g., an input-compensated DSC from Perkin-Elmer, DiamondDSC) under a nitrogen flow, heated from -40°C to 300°C at a rate of 20°C / min, held at 300°C for 5 minutes, cooled to -40°C at 20°C / min, held at -40°C for 5 minutes, and then heated again to 300°C at 20°C / min. On the other hand, an amorphous thermoplastic resin is a thermoplastic resin in which a clear melting peak does not appear in the above measurement using a DSC.

[0040] Examples of crystalline thermoplastic resins include a wide range of known crystalline polyolefin resins. Examples of crystalline polyolefin resins include polymers obtained by polymerizing olefins, preferably polymers obtained by polymerizing olefins having 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 3 to 6 carbon atoms. Specifically, examples of crystalline polyolefin resins include crystalline polyethylene resin, polypropylene resin, poly(1-butene) resin, polyisobutene resin, poly(1-pentene) resin, and poly(4-methylpentene-1) resin. The crystalline polyolefin resin is preferably a crystalline polypropylene resin because it is easily miscible (compatible) with the polylactic acid. The crystalline polyolefin resin can be a single type or a mixture of two or more types.

[0041] Furthermore, thermoplastic resins that contribute to heat sealability include, for example, thermoplastic resins with a melting point of less than 150°C, and particularly those with a melting point of 60°C to 145°C. Specifically, examples include crystalline propylene-α-olefin random copolymers, and as α-olefins, ethylene or α-olefins having 4 to 20 carbon atoms. It is preferable to use ethylene, butene-1, hexene-1, octene-1, etc., and it is even more preferable to use copolymers or terpolymers using ethylene or butylene. Particularly preferred are ethylene-propylene-1-butene copolymer (5C37F, manufactured by Sun Allomer Co., Ltd., melting point 142°C), propylene-ethylene-butene random copolymer (FL6741G, manufactured by Sumitomo Chemical Co., Ltd., melting point 130°C), and propylene-1-butene copolymer (Tafmer XM7070S, manufactured by Mitsui Chemicals, Inc., melting point 75°C).

[0042] The content of other resins in the biodegradable film of the first embodiment of the present invention can be appropriately set within a range that does not impair the effects of the present invention. However, if other resins are included, for example, it is preferably about 0.1 to 20% by mass, and more preferably about 5 to 10% by mass, of 100% by mass of the resin component.

[0043] (Biodegradability of the biodegradable film of the first embodiment of the present invention) The biodegradability of the biodegradable film of the first embodiment of the present invention is measured by the elongation at break A at the time of test specimen preparation, measured under the following measurement conditions (I). ０ The elongation at break A of the test specimen after 48 hours of constant temperature and humidity treatment, measured according to the following measurement conditions (II): ４８ Ratio A ４８ / A ０ It is preferable that the value is 0.8 or less; <Measurement conditions (I)> A test piece (15 mm wide, 170 mm long) is cut from the biodegradable film and subjected to a tensile test using a Tensilon universal tester (Orientec Co., Ltd. "Model number RTG-1210") at a tensile speed of 200 mm / min and a chuck distance of 100 mm, and the elongation at break (%) is measured (A ０). <Measurement conditions (II)> The above test piece is cut separately from the same film, left to stand for 48 hours in a constant temperature and humidity chamber set to 60°C and 95% humidity, and then subjected to the above tensile test and the elongation at break (%) is measured (A ４８ ). However, under measurement condition (II), the elongation at break of the film that breaks before being subjected to the tensile test described above shall be 0%.

[0044] Ratio A of the above fracture elongation ４８ / A ０ A smaller value indicates higher hydrolysis potential of the biodegradable film (polylactic acid). The ratio is preferably 0.8 or less, more preferably 0.7 or less, even more preferably 0.6 or less, and particularly preferably 0.5 or less. While there is no practical lower limit to this ratio, it is approximately 0.1.

[0045] Furthermore, the biodegradability of the biodegradable film according to the first embodiment of the present invention can also be evaluated by specific biodegradability tests. For example, a test piece (100 mm wide, 100 mm long) can be cut from the biodegradable film, buried in leaf mold, and left to stand in a constant temperature and humidity chamber set to 58°C and 95% humidity. The biodegradability can be evaluated by the time it takes for the test piece to disintegrate. Note that "disintegration" of the test piece means that the test piece can no longer maintain its shape when lifted by hand.

[0046] According to the evaluation of the biodegradability test described above, the biodegradable film of the first embodiment of the present invention preferably has a period of 5 weeks or less before the test piece disintegrates, more preferably 4 weeks or less, and even more preferably 3 weeks or less.

[0047] (Layer structure of the biodegradable film of the first embodiment of the present invention) The biodegradable film of the first embodiment of the present invention may be a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, it may be a laminated film comprising layer a (core layer) and layers other than layer a (other layers). In the case of a multi-layer structure, it is preferable that layer a (core layer) contains (A) polylactic acid and (B) a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule.

[0048] Other layers include, for example, layer b formed of resin. That is, one embodiment of the biodegradable film of the first embodiment of the present invention includes layer b on one or both sides of layer a, and layer b contains, for example, a crystalline polyolefin resin having a melting point of 150 to 175°C. In this case, layer b can act as a so-called skin layer, making the biodegradable film smoother.

[0049] Layer b may be laminated by directly bonding it to layer a, or another layer may be interposed between layer a and layer b. From the viewpoint of reducing the haze of the biodegradable film of the present invention, it is preferable that layer b is laminated by directly bonding it to layer a.

[0050] If layer b is formed on both sides of layer a, the layers b may be made of the same components, or they may be made of different components.

[0051] The method for forming layer a, the method for laminating layer b, etc., will be explained later in the section on the method for manufacturing biodegradable film.

[0052] The biodegradable film of the first embodiment of the present invention may also include layers other than layer b, either together with or in place of layer b. For example, a heat-seal layer may be included as a layer other than layer b. In other words, the biodegradable film of the first embodiment of the present invention may have a heat-seal layer on at least one side. This can improve the heat-sealability of the biodegradable film. Here, the heat-seal layer refers to a layer other than layer b. Heat-sealability means that when two heat-seal layers are overlapped facing each other and heat-pressed, they fuse together. Furthermore, other layers c may be laminated.

[0053] As described above, the biodegradable film of the first embodiment of the present invention may have layer a as a core layer, and optionally at least one layer selected from the group consisting of layer b, a heat seal layer, and layer c laminated to it. More specifically, the biodegradable film of the first embodiment of the present invention may include a laminate (i.e., b / a / b) in which layer a is used as a core layer and layer b is directly bonded to one or both sides thereof. Alternatively, the biodegradable film of the first embodiment of the present invention may include a laminate (i.e., b / a / heat seal layer, or b / a / c) in which layer a is used as a core layer, layer b is directly bonded to one side thereof, and a heat seal layer or layer c is bonded to the opposite side. Furthermore, the biodegradable film of the first embodiment of the present invention may include a laminate (i.e., heat seal layer / a / heat seal layer) in which layer a is used as a core layer and heat seal layers are directly bonded to both sides thereof. Furthermore, the biodegradable film of the first embodiment of the present invention may include a laminate (i.e., c / a / c) in which layer a is used as a core layer and layer c is directly bonded to both sides thereof. Moreover, the biodegradable film of the first embodiment of the present invention may include a laminate (i.e., heat-seal layer / a / c) in which layer a is used as a core layer, a heat-seal layer is directly bonded to one side thereof, and layer c is bonded to the opposite side. Furthermore, the biodegradable film of the first embodiment of the present invention can be a stretched film in either a single-layer or multi-layer configuration. In the case of a stretched film, a biaxially stretched film is preferred.

[0054] As described above, the biodegradable film of the first embodiment of the present invention includes the case of a multilayer structure, but the phosphorus atom content and biodegradability in the biodegradable film mentioned above refer to the content and characteristics in layer a (core layer) containing (A) polylactic acid and (B) a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule.

[0055] (Optional Additives) The biodegradable film of the first embodiment of the present invention may optionally contain additives. Examples of additives include those used in known biodegradable films, such as heat stabilizers, antioxidants, organic and inorganic lubricants, antiblocking agents (AB agents), chlorine scavenging agents, antistatic agents, and antifogging agents.

[0056] Examples of heat stabilizers and antioxidants include phenolic, hindered amine, phosphite, lactone, and tocopherol-based heat stabilizers and antioxidants. Specifically, examples include dibutylhydroxytoluene, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (BASF Japan Ltd.'s "Irganox® 1010"), and 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxy)benzene (BASF Japan Ltd.'s "Irganox® 1330"). Among these, at least one selected from the phenolic antioxidant system or a combination thereof, or a combination of phenolic and phosphite systems, and combinations of phenolic and lactone systems, or phenolic, phosphite, and lactone systems are preferred from the viewpoint of providing chemical stability to the film.

[0057] Examples of lubricants include organic lubricants such as stearic acid amide, erucic acid amide and other aliphatic amides, lauryl acid diethanolamide, alkyldiethanolamine, aliphatic monoglycerides, aliphatic diglycerides, and silicone crosslinked polymers, as well as inorganic lubricants such as silica and alumina. However, organic lubricants that cause less contamination of printing plates are preferred for printing applications.

[0058] Examples of antiblocking agents (AB agents) include acrylic AB agents as organic AB agents, and silica AB agents as inorganic AB agents.

[0059] Examples of chlorine-scavenging agents include calcium stearate, metallic soaps, and hydrotalcite.

[0060] Examples of antistatic agents include alkylmethyl dibetaine, alkylamine diethanol and / or alkylamine ethanol ester and / or alkylamine diethanol diester. Two or more of these antistatic agents may be used in combination, and aliphatic alcohols may also be used in combination. Among these, the combination of stearyldiethanolamine monostearate and stearyldiethanolamine is preferred because it provides excellent antistatic performance and improves printability. Representative examples of commercially available antistatic agents include the Electro Stripper (registered trademark) series manufactured by Kao Corporation.

[0061] The type of antifogging agent is not particularly limited, and a wide range of antifogging agents used in general polyolefin films can be cited as examples. For example, antifogging agents include glycerin, polyethylene glycol, pentaerythritol, sorbitol, polypropylene glycol, and other polyhydric alcohols with higher fatty acids such as lauric acid, stearic acid, and oleic acid, ethylene oxide adducts of higher aliphatic amines, higher aliphatic alkanolamides, higher alcohol phosphate ester salts, and mixtures thereof.

[0062] The thickness of the biodegradable film of the first embodiment of the present invention is not particularly limited, but from the viewpoint of ensuring a certain strength, it is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 12 μm or more. From the viewpoint of transparency, the thickness is preferably 100 μm, more preferably 70 μm, even more preferably 50 μm or less, even more preferably 40 μm or less, particularly preferably 30 μm or less, and especially preferably 25 μm or less. When the biodegradable film of the present invention has the above-mentioned multilayer structure, the thickness of the biodegradable film of the present invention refers to the sum of the thicknesses of each layer. The thickness is measured by the method described in the examples of the first embodiment below.

[0063] The biodegradable film of the present invention can be suitably used for heat-sealable bags, packaging, food packaging, pharmaceutical packaging, decoration (including fashion), labels, tape substrates, printing substrates, stationery, home appliances, poster paper, thermal paper substrates, recording paper substrates, interior and exterior applications for houses, automobiles, containers, and the like.

[0064] Laminate using the biodegradable film of the first embodiment The biodegradable film of the first embodiment of the present invention is preferably used as a laminate having a biodegradable film and a substrate. That is, the present invention also includes such laminate.

[0065] Biodegradable films and substrates can be bonded together by a known lamination process such as dry lamination or melt extrusion lamination, with an adhesive layer or adhesive resin layer between them, and surface treatment such as corona treatment applied as necessary.

[0066] Examples of suitable base materials include polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), polyvinyl chloride resins, fluororesins, poly(meth)acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resins such as various types of nylon, polyimide resins, polyamide-imide resins, polyarylphthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, polyurethane resins, acetal resins, cellulose resins, and various other resin films or sheets, paper, etc. Among these, polyethylene film and uniaxially oriented polypropylene (CPP) are preferred as base materials from the viewpoint of flexibility and heat sealability. It is preferable that the base material contains biomass plastic.

[0067] The method for manufacturing the biodegradable film according to the first embodiment of the present invention is not particularly limited, and for example, known manufacturing methods can be widely employed. For example, in a preferred embodiment, when manufacturing a biaxially stretched biodegradable film, a resin raw material containing at least (A) polylactic acid and (B) a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule is extruded to obtain a resin sheet for layer a, then, for example, a lamination process for layer b and / or a heat-seal layer is performed to form a laminated sheet, and then this laminated sheet is stretched to manufacture the biodegradable film of the present invention. Such a manufacturing method is abbreviated as "manufacturing method A". The resin components constituting each layer, and the types and contents of any additives are as described above.

[0068] The method for preparing the resin raw material can be, for example, the same as known preparation methods, and includes methods such as dry blending resin pellets or powders using a batch-type mixing device such as a tumbler or mixer, or a continuous weighing-type mixing device; or supplying resin pellets or powders together with other resin pellets or powders and / or additives as needed to a kneader and melt-kneading to obtain a melt-blended resin composition. Among these, it is preferable to prepare the resin raw material by melt-kneading.

[0069] For the mixing machine used for melting and kneading, a known mixing machine can be used, and a single-screw type, a twin-screw type, or a multi-screw type with more than one screw may be used. Furthermore, in the case of a twin-screw type, either a mixing type with co-rotation or opposite rotation may be used.

[0070] The mixing temperature for melt mixing is preferably in the range of 200°C to 300°C, and more preferably in the range of 220°C to 280°C. When blending polylactic acid with other resins, using the above temperature range allows for more uniform mixing of multiple resin components. To prevent degradation of the resin during melt mixing, an inert gas such as nitrogen can be purged. The melt-mixed resin can be pelletized to an appropriate size using a generally known granulator to obtain melt-blended resin composition pellets.

[0071] In manufacturing method A, a resin sheet can be obtained using the resin raw material obtained as described above. Specifically, the resin raw material is supplied to an extruder, heated and melted, and if necessary, minute foreign matter is removed using a filter or the like. Then, the resin sheet can be obtained by melt-extruding it into a sheet shape from a T-die.

[0072] For obtaining the resin sheet, any known extruder can be widely used. There are no restrictions on the screw type of the extruder; a single-screw type, a twin-screw type, or a multi-screw type with more than one screw may be used. When the resin raw material is prepared using the dry blend described above, using a twin-screw type or a multi-screw type with more than one screw tends to provide better mixing and dispersibility. The extrusion temperature is preferably in the range of 200°C to 300°C, and more preferably in the range of 220°C to 280°C. To prevent thermal degradation of the resin during extrusion, purging with an inert gas such as nitrogen can be performed.

[0073] The melt-extruded resin sheet is formed into a sheet shape by known methods, such as by pressing it onto at least one metal drum set to a temperature of 25 to 120°C using an air knife, other rolls, or static electricity, and the resin sheet is obtained as a so-called raw material sheet. A more preferred temperature for the metal drum is 30 to 80°C.

[0074] Manufacturing method A further comprises a lamination step of laminating, for example, layer b and / or a heat-seal layer onto layer a. In the lamination step, a wide range of conventional lamination methods can be used, for example, films obtained by lamination using co-extrusion, lamination, heat-sealing, etc.

[0075] Specifically, when manufacturing a stretched film having a laminated structure, a resin sheet having a laminated structure can be obtained by co-extruding two or more dry blend and / or melt blend resin compositions (the composition of each resin composition may be different or the same), and then stretching such a resin sheet having a laminated structure. Alternatively, a stretched film having a laminated structure can also be manufactured by laminating a single-layer stretched film with another film. Furthermore, a stretched film having a laminated structure can also be manufactured by stretching a multilayer unstretched film (the composition of the resin composition constituting each layer may be different or the same) obtained by laminating two or more unstretched films extruded as single layers together.

[0076] Examples of the aforementioned co-extrusion methods include pre-die lamination, in which the molten resin is brought into contact within a feed block in front of the mold; in-die lamination, in which contact occurs within a path inside the mold, such as a multi-manifold die; and off-die lamination, in which the molten resin is extruded and brought into contact from multiple concentric lips. For example, in the in-die lamination method, a multilayer die such as a three-layer multi-manifold die can be used to create a three-layer structure consisting of a surface layer (skin layer: layer b) and a core layer (intermediate layer: layer a), such as layer b / layer a / layer b.

[0077] Lamination methods include the extrusion lamination method, which uses the equipment for the molten extrusion molding method used in the T-die method to directly extrude a film of molten resin onto another film to form a laminated film.

[0078] Heat sealing methods include external heating methods, in which a heated metal object is pressed against multiple films to be bonded together from the outside of the films, and the conducted heat melts and bonds the films, and internal heating methods, in which heat is generated in the films using high-frequency radio waves or ultrasound to bond them.

[0079] In manufacturing method A, the above lamination methods can be used individually or in combination.

[0080] In manufacturing method A, a resin sheet (raw sheet) having the above-described laminated structure is subjected to biaxial stretching. As for the stretching method, known methods such as stretching between rolls with a difference in peripheral speed, the tenter method, and the tubular method can be used. Both sequential stretching and simultaneous stretching are applicable during biaxial stretching. Of these, simultaneous biaxial stretching using the tenter method, sequential biaxial stretching using the tenter method, and sequential biaxial stretching in which the longitudinal (flow, MD) stretching is performed between rolls with a difference in peripheral speed, followed by transverse (width, TD) stretching using the tenter method are preferred because they make it easier to obtain the desired stretched film. The following describes a method for obtaining the biodegradable film (stretched film) of the present invention by sequential biaxial stretching, but is not limited thereto.

[0081] In the sequential biaxial stretching method, it is preferable to adjust the stretching temperature and stretching ratio according to the melting point and glass transition temperature of the resin used. First, the resin sheet (raw material sheet) is kept at a temperature of preferably 40 to 120°C, more preferably 50 to 100°C, and even more preferably 60 to 90°C, and stretched in the longitudinal direction by preferably 1.5 to 4 times, more preferably 1.8 to 2.5 times, by passing it between rolls with a difference in peripheral speed, or by the tenter method. Subsequently, the stretched film is stretched in the transverse direction by preferably 2 to 5 times, more preferably 2.5 to 4 times, at a temperature of preferably 40 to 120°C, more preferably 50 to 100°C, and even more preferably 60 to 90°C, using the tenter method. After that, the film is subjected to a heat treatment, which includes a relaxation treatment and a heat setting treatment, before being wound up. The wound film can be aged in an atmosphere of preferably 20 to 45°C, and then cut to the desired product width.

[0082] The wound film can be aged in an atmosphere of approximately 20 to 45°C before being cut to the desired product width. In this way, a stretched film with excellent stretchability, transparency, mechanical strength, etc., can be obtained.

[0083] A preferred embodiment of manufacturing method A includes a step of providing layer b and / or a heat seal layer on one or both sides of layer a, providing single layers made of crystalline thermoplastic resin A at both lateral ends of the obtained laminated sheet to form a resin sheet, and then gripping and stretching at least the single layers at both ends. According to this method, low-tack single layers can be provided at both lateral ends using a feed block and a single-layer T-die, and after gripping the single layers with clips using the tenter method and stretching at least in the lateral direction, a multilayer stretched film having at least layer a can be obtained by trimming the single layers. The width (on one side) of the single layer is not particularly limited, but is preferably about 1 to 30% of the total width of the unstretched resin sheet, and more preferably about 2 to 30%.

[0084] <Second Embodiment> 2-1. Biodegradable Film A second embodiment of the present invention relates to a biodegradable film (hereinafter, in the scope describing the biodegradable film of the second embodiment of the present invention, the biodegradable film of the second embodiment of the present invention will also be referred to as the "biodegradable film of the second embodiment" or simply the "biodegradable film") containing, in one embodiment, (A) polylactic acid, (B) an aromatic phosphite ester compound having two or more phosphorus atoms in one molecule (hereinafter, in the scope describing the biodegradable film of the second embodiment of the present invention, it may also be referred to as the "aliphatic phosphite ester compound of the present invention"), and (C) an aliphatic phosphite ester compound having two or more phosphorus atoms in one molecule (hereinafter, in the scope describing the biodegradable film of the second embodiment of the present invention, it may also be referred to as the "biodegradable film of the second embodiment" or simply the "biodegradable film").

[0085] The polylactic acid is not particularly limited, and known polylactic acids can be widely used, for example, polylactic acid obtained by condensation polymerization of lactic acid components as raw material monomers. The polylactic acid may contain only one optical isomer of L-lactic acid (L-isomer) and D-lactic acid (D-isomer), or both.

[0086] When polylactic acid mainly consists of L-lactic acid (L-isomer), the content of the D-isomer can be, for example, 15.0 mol% or less, preferably 10.0 mol% or less, more preferably 8.0 mol% or less, even more preferably 7.0 mol% or less, even more preferably 6.0 mol% or less, and particularly preferably 5.0 mol% or less. Among these, it is even more preferable that it be 3.0 mol% or less, even more preferably 1.0 mol% or less, and most preferably 0.01 mol% or less. Furthermore, the lower limit of the D-isomer content is preferable as much as possible, and may be, for example, 0 mol%. When polylactic acid mainly consists of D-lactic acid (D-isomer), the content of the L-isomer can be, for example, 15.0 mol% or less, preferably 10.0 mol% or less, more preferably 8.0 mol% or less, even more preferably 7.0 mol% or less, even more preferably 6.0 mol% or less, and particularly preferably 5.0 mol% or less. Among these, it is more preferable that the content be 3.0 mol% or less, even more preferable that it be 1.0 mol% or less, and most preferable that it be 0.01 mol% or less. Furthermore, the lower limit of the L-isomer content is preferable as much as possible, and may be, for example, 0 mol%. The glass transition temperature, crystallization temperature, molecular weight, etc. of the above polylactic acid are not particularly limited.

[0087] The melting point of polylactic acid is preferably 110°C to 200°C. When the melting point of polylactic acid is within this range, it is easier to maintain good heat resistance and productivity of the resulting biodegradable film. In addition, if the biodegradable film is a stretched film, it becomes easier to adjust the stretching ratio. The melting point of polylactic acid is preferably 120°C to 190°C, more preferably 130°C to 185°C, and even more preferably 140°C to 180°C.

[0088] The glass transition temperature of polylactic acid is not particularly limited and can be, for example, -40°C to 70°C, with 0°C to 70°C being more preferable.

[0089] In this specification, the melting point and glass transition temperature of polylactic acid are values ​​measured using a differential scanning calorimeter (e.g., input-compensated DSC, DiamondDSC, manufactured by Perkin-Elmer).

[0090] The melt mass flow rate (MFR) of polylactic acid is not particularly limited. Preferably, the melt mass flow rate of polylactic acid is 0.5 g / 10 min to 15 g / 10 min, more preferably 1 g / 10 min to 10 g / 10 min, and even more preferably 2 g / 10 min to 10 g / 10 min, as this allows for a suitable resin fluidity and facilitates the production of the desired biodegradable film. In this specification, the melt mass flow rate refers to the value measured at 230°C and 21.18 N in accordance with JIS K-7210 (1999).

[0091] The method for producing polylactic acid is not particularly limited, and for example, known methods for producing polylactic acid can be widely adopted. In addition, commercially available polylactic acid can also be used. Representative commercially available polylactic acid products include NatureWorks' "4032D" (melting point 163°C), Total Corbion PLA's "L175" (melting point 175°C), "LX175" (melting point 155°C), and "LX930" (melting point 130°C).

[0092] The biodegradable film of the second embodiment of the present invention contains polylactic acid as a main component. The polylactic acid content is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, particularly more preferably 97% by mass or more, particularly more preferably 98% by mass or more, and especially preferably 98.5% by mass or more, based on 100% by mass of the biodegradable film of the second embodiment of the present invention. There is no particular upper limit to the polylactic acid content, and it is, for example, 99.8% by mass or less, 99.7% by mass or less, 99.5% by mass or less, or 99.0% by mass or less, relative to 100% by mass of the biodegradable film of the second embodiment of the present invention or relative to 100% by mass of the resin components contained in the biodegradable film of the second embodiment of the present invention.

[0093] The resin component content is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 97% by mass or more, particularly preferably 98% by mass or more, and especially preferably 98.5% by mass or more, based on 100% by mass of the biodegradable film of the second embodiment of the present invention. The upper limit of the resin component content is not particularly limited and is, for example, 99.8% by mass or less, 99.7% by mass or less, 99.5% by mass or less, or 99.0% by mass or less, based on 100% by mass of the biodegradable film of the second embodiment of the present invention.

[0094] Other resins besides polylactic acid that can constitute the resin component are not particularly limited as long as they do not impair the effects of the present invention, but examples include known crystalline thermoplastic resins and known thermoplastic resins that can impart heat-sealability to biodegradable films.

[0095] In this specification, a crystalline thermoplastic resin is a thermoplastic resin in which a clear melting peak appears in the DSC curve when measured using a differential scanning calorimeter (e.g., an input-compensated DSC from Perkin-Elmer, DiamondDSC) under a nitrogen flow, heated from -40°C to 300°C at a rate of 20°C / min, held at 300°C for 5 minutes, cooled to -40°C at 20°C / min, held at -40°C for 5 minutes, and then heated again to 300°C at 20°C / min. On the other hand, an amorphous thermoplastic resin is a thermoplastic resin in which a clear melting peak does not appear in the above measurement using a DSC.

[0096] Examples of crystalline thermoplastic resins include a wide range of known crystalline polyolefin resins. Examples of crystalline polyolefin resins include polymers obtained by polymerizing olefins, preferably polymers obtained by polymerizing olefins having 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 3 to 6 carbon atoms. Specifically, examples of crystalline polyolefin resins include crystalline polyethylene resin, polypropylene resin, poly(1-butene) resin, polyisobutene resin, poly(1-pentene) resin, and poly(4-methylpentene-1) resin. The crystalline polyolefin resin is preferably a crystalline polypropylene resin because it is easily miscible (compatible) with the polylactic acid. The crystalline polyolefin resin can be a single type or a mixture of two or more types.

[0097] Furthermore, thermoplastic resins that contribute to heat sealability include, for example, thermoplastic resins with a melting point of less than 150°C, and particularly those with a melting point of 60°C to 145°C. Specifically, examples include crystalline propylene-α-olefin random copolymers, and as α-olefins, ethylene or α-olefins having 4 to 20 carbon atoms. It is preferable to use ethylene, butene-1, hexene-1, octene-1, etc., and it is even more preferable to use copolymers or terpolymers using ethylene or butylene. Particularly preferred are ethylene-propylene-1-butene copolymer (5C37F, manufactured by Sun Allomer Co., Ltd., melting point 142°C), propylene-ethylene-butene random copolymer (FL6741G, manufactured by Sumitomo Chemical Co., Ltd., melting point 130°C), and propylene-1-butene copolymer (Tafmer XM7070S, manufactured by Mitsui Chemicals, Inc., melting point 75°C).

[0098] The content of other resins in the biodegradable film of the second embodiment of the present invention can be appropriately set within a range that does not impair the effects of the present invention. For example, with respect to 100% by mass of the resin component contained in the biodegradable film of the second embodiment of the present invention, the content of other resins can be appropriately set within a range that does not impair the effects of the present invention. For example, it can be 0 to 20% by mass, preferably 0 to 10% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 2% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0 to 0.1% by mass.

[0099] The aromatic phosphite ester compounds of the present invention are not particularly limited, as long as they have two or more phosphorus atoms and one or more aromatic rings in one molecule. The aromatic phosphite ester compounds of the present invention serve as decomposition accelerators that promote the hydrolysis (biodegradability) of polylactic acid in biodegradable films.

[0100] Phosphite ester compounds that contain only one phosphorus atom per molecule either fail to hydrolyze polylactic acid or have little effect at all. The aromatic phosphite ester compounds of the present invention have a high biodegradability (hydrolysis) promoting effect on polylactic acid and, due to the presence of an aromatic ring, have high heat resistance, which in turn makes them less likely to contaminate equipment during film formation. On the other hand, the aliphatic phosphite ester compounds of the present invention, described later, do not have an aromatic ring and, due to their low heat resistance, are relatively prone to contaminating equipment during film formation, although they have a particularly high biodegradability (hydrolysis) promoting effect on polylactic acid. Therefore, by combining these, it is possible to provide a biodegradable film that contains polylactic acid, has a certain level of biodegradability, and suppresses equipment contamination.

[0101] The number of phosphorus atoms (preferably in the phosphorus ester structure) in the molecule (or repeating unit) of the aromatic phosphite ester compound of the present invention is, for example, 2 to 10, preferably 2 to 5, more preferably 2 to 3, and particularly preferably 2.

[0102] The phosphite ester structure is represented by the general formula (II-X):

[0103] The structure is represented by the formula. In the formula, R is the same or different and represents a hydrocarbon group.

[0104] The number of aromatic rings in the molecule (or repeating unit) of the aromatic phosphite compound of the present invention is, for example, 1 to 10, preferably 2 to 10, more preferably 2 to 8, even more preferably 2 to 6, even more preferably 2 to 4, particularly preferably 2 to 3, and especially preferably 2.

[0105] The aromatic ring is not particularly limited and can be, for example, a monoring or a fused ring, and can be an aromatic hydrocarbon ring or a heteroaromatic ring. The aromatic ring is preferably a monoring and preferably an aromatic hydrocarbon ring. Examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, etc., with benzene rings being particularly preferred.

[0106] The molecular weight of the aromatic phosphite ester compound of the present invention is, for example, 300 to 3000, preferably 400 to 2000, more preferably 450 to 1000, even more preferably 500 to 900, even more preferably 500 to 800, and particularly preferably 550 to 700.

[0107] The aromatic phosphite ester compound of the present invention is preferably of formula (II-I):

[0108] It has a substructure represented by . In this case, the number of such substructures in the molecule is, for example, 1 to 5, preferably 1 to 3, more preferably 1 to 2, and particularly preferably 1.

[0109] The aromatic phosphite ester compound of the present invention is preferably of general formula (II-II):

[0110] [In the formula, R １ and R ２ The same or different groups represent hydrocarbon groups having an aromatic ring. Compounds represented by ], or general formula (II-III):

[0111] [In the formula, R ３ represents a hydrocarbon group having an aromatic ring. The compound contains a repeating structure of the unit represented by ]. Among these, compounds represented by the general formula (II-II) are particularly preferred.

[0112] R １ and R ２ The hydrocarbon group shown is a monovalent hydrocarbon group, R ３ The hydrocarbon group shown is a divalent hydrocarbon group.

[0113] The hydrocarbon group in general formulas (II-II) and (II-III) is not particularly limited as long as it contains an aromatic ring, and can be, for example, an aromatic ring, a hydrocarbon chain (straight or branched), an aliphatic hydrocarbon ring, or a group formed by an appropriate combination thereof.

[0114] The number of aromatic rings contained in the hydrocarbon group in general formulas (II-II) and (II-III) is, for example, 1 to 5, preferably 1 to 3, more preferably 1 to 2, and particularly preferably 1.

[0115] The hydrocarbon chain is preferably a saturated hydrocarbon chain, and its carbon number is, for example, 1 to 12, preferably 1 to 10, more preferably 1 to 8, and even more preferably 1 to 6.

[0116] The number of carbon atoms in the hydrocarbon group in general formulas (II-II) and (II-III) is, for example, 6 to 50, preferably 8 to 30, more preferably 10 to 20, and even more preferably 12 to 18.

[0117] The hydrocarbon group in general formulas (II-II) and (II-III) is a monovalent or divalent group obtained by removing one or two ring-constituting hydrogens from a benzene ring, which may be substituted with one to three substituents (preferably alkyl groups (e.g., having 1 to 10 carbon atoms, preferably 1 to 8, more preferably 1 to 6 carbon atoms), aryl groups (preferably phenyl groups), and arylalkyl groups (preferably phenylalkyl groups (for alkyl groups, as defined above)), more preferably alkyl groups).

[0118] The melting point of the aromatic phosphite compound of the present invention is, for example, 140 to 350°C, preferably 150 to 300°C, and more preferably 160 to 260°C.

[0119] Preferred specific examples of the aromatic phosphite ester compounds of the present invention include compounds 2-1, 2-2, and 2-3 described in the examples below, with compound 2-1 being particularly preferred.

[0120] The content of the aromatic phosphite compound of the present invention is not limited as long as a biodegradable film with a certain level of biodegradability while suppressing equipment contamination can be obtained by combining it with the aliphatic phosphite compound of the present invention, but is, for example, 0.3 to 5.0 parts by mass per 100 parts by mass of polylactic acid (or a resin component containing polylactic acid). From the viewpoint of promoting biodegradability (hydrolysis), the content is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more, even more preferably 0.8 parts by mass or more, and even more preferably 0.9 parts by mass or more. In one embodiment (for example, from the viewpoint that biodegradability (hydrolysis) can be effectively promoted with a smaller content by combining it with the aliphatic phosphite compound of the present invention described later), the content is preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, even more preferably 2.0 parts by mass or less, even more preferably 1.5 parts by mass or less, particularly preferably 1.2 parts by mass or less, and especially preferably 1.0 part by mass or less.

[0121] The aliphatic phosphite ester compounds of the present invention are not particularly limited, as long as they have two or more phosphorus atoms in one molecule, do not contain an aromatic ring in the molecule, and have an aliphatic hydrocarbon group. The aliphatic phosphite ester compounds of the present invention serve as decomposition accelerators that promote the hydrolysis (biodegradability) of polylactic acid in biodegradable films.

[0122] The number of phosphorus atoms (preferably in the phosphorus ester structure) in the molecule (or repeating unit) of the aliphatic phosphite compound of the present invention is, for example, 2 to 10, preferably 2 to 5, more preferably 2 to 3, and particularly preferably 2.

[0123] The molecular weight of the aliphatic phosphite compound of the present invention is, for example, 300 to 3000, preferably 400 to 2500, more preferably 450 to 1500, even more preferably 500 to 1000, and particularly preferably 600 to 800.

[0124] The aliphatic phosphite ester compound of the present invention preferably has a substructure represented by the above formula (II-I). In this case, the number of such substructures in the molecule is, for example, 1 to 5, preferably 1 to 3, more preferably 1 to 2, and particularly preferably 1.

[0125] The aliphatic phosphite ester compound of the present invention is preferably of general formula (II-IV):

[0126] [In the formula, R ４ and R ５ These are the same or different, and represent an aliphatic hydrocarbon group. Compounds represented by ] or general formula (II-V):

[0127] [In the formula, R ６ represents an aliphatic hydrocarbon group. The compound contains a repeating structure of the unit represented by ]. Among these, compounds represented by the general formula (II-IV) are particularly preferred.

[0128] R ４ and R ５ The aliphatic hydrocarbon group shown is a monovalent aliphatic hydrocarbon group, R ６ The aliphatic hydrocarbon group shown is a divalent hydrocarbon group.

[0129] The aliphatic hydrocarbon group in general formulas (II-IV) and (II-V) is not particularly limited and can be, for example, a hydrocarbon chain (straight or branched), an aliphatic hydrocarbon ring, or a group formed by a suitable combination thereof.

[0130] The hydrocarbon chain is preferably a saturated hydrocarbon chain, and its carbon number is, for example, 1 to 50, preferably 6 to 40, more preferably 8 to 30, and even more preferably 12 to 24.

[0131] The number of carbon atoms in the aliphatic hydrocarbon group in general formulas (II-IV) and (II-V) is, for example, 1 to 50, preferably 6 to 40, more preferably 8 to 30, and even more preferably 12 to 24.

[0132] The aliphatic hydrocarbon group in general formulas (II-IV) and (II-V) is preferably a hydrocarbon chain, and particularly preferably a linear hydrocarbon chain.

[0133] The aliphatic phosphite ester compound of the present invention is preferably a solid at room temperature (20°C). The melting point or softening point of the aliphatic phosphite ester compound of the present invention is, for example, 35 to 120°C, preferably 40 to 100°C, and more preferably 45 to 80°C.

[0134] Preferred specific examples of the aliphatic phosphite ester compounds of the present invention include compounds 2-4 and 2-5 of the examples described later, with compound 2-4 being particularly preferred.

[0135] The content of the aliphatic phosphite compound of the present invention is not limited as long as a biodegradable film with a certain level of biodegradability while suppressing equipment contamination can be obtained by combining it with the aromatic phosphite compound of the present invention, but is, for example, 0.01 to 0.5 parts by mass per 100 parts by mass of polylactic acid (or a resin component containing polylactic acid). From the viewpoint of promoting biodegradability (hydrolysis), the content is preferably 0.02 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.08 parts by mass or more, even more preferably 0.1 parts by mass or more, particularly preferably 0.12 parts by mass or more, particularly more preferably 0.15 parts by mass or more, even more preferably 0.17 parts by mass or more, and especially preferably 0.18 parts by mass or more. From the viewpoint of further suppressing equipment contamination, the content is preferably 0.4 parts by mass or less, more preferably 0.3 parts by mass or less, even more preferably 0.25 parts by mass or less, and even more preferably 0.22 parts by mass or less.

[0136] The biodegradable film of the second embodiment of the present invention may optionally contain additives as components. Examples of additives include those used in known biodegradable films, such as heat stabilizers, antioxidants, organic and inorganic lubricants, antiblocking agents (AB agents), chlorine scavenging agents, antistatic agents, and antifogging agents. In one embodiment, the film of the present invention contains an antiblocking agent.

[0137] Examples of heat stabilizers and antioxidants include phenolic, hindered amine, phosphite, lactone, and tocopherol-based heat stabilizers and antioxidants. Specifically, examples include dibutylhydroxytoluene, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (BASF Japan Ltd.'s "Irganox® 1010"), and 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxy)benzene (BASF Japan Ltd.'s "Irganox® 1330"). Among these, at least one selected from the phenolic antioxidant system or a combination thereof, or a combination of phenolic and phosphite systems, and combinations of phenolic and lactone systems, or phenolic, phosphite, and lactone systems are preferred from the viewpoint of providing chemical stability to the film.

[0138] Examples of lubricants include organic lubricants such as stearic acid amide, erucic acid amide and other aliphatic amides, lauryl acid diethanolamide, alkyldiethanolamine, aliphatic monoglycerides, aliphatic diglycerides, and silicone crosslinked polymers, as well as inorganic lubricants such as silica and alumina. However, organic lubricants that cause less contamination of printing plates are preferred for printing applications.

[0139] Antiblocking agents are not particularly limited, but examples include inorganic antiblocking agents such as silica, zeolite, talc, wollastonite, kaolin, imogolite, halloysite, attapulgite, calcium carbonate, and diatomaceous earth; and organic antiblocking agents such as resin particles like acrylic resin, wax, paraffin, alkylene oxide, fatty acid soap, fatty acid amide, and silicone.

[0140] Examples of chlorine-scavenging agents include calcium stearate, metallic soaps, and hydrotalcite.

[0141] Examples of antistatic agents include alkylmethyl dibetaine, alkylamine diethanol and / or alkylamine ethanol ester and / or alkylamine diethanol diester. Two or more of these antistatic agents may be used in combination, and aliphatic alcohols may also be used in combination. Among these, the combination of stearyldiethanolamine monostearate and stearyldiethanolamine is preferred because it provides excellent antistatic performance and improves printability. Representative examples of commercially available antistatic agents include the Electro Stripper (registered trademark) series manufactured by Kao Corporation.

[0142] The type of antifogging agent is not particularly limited, and a wide range of antifogging agents used in general polyolefin films can be cited as examples. For example, antifogging agents include glycerin, polyethylene glycol, pentaerythritol, sorbitol, polypropylene glycol, and other polyhydric alcohols with higher fatty acids such as lauric acid, stearic acid, and oleic acid, ethylene oxide adducts of higher aliphatic amines, higher aliphatic alkanolamides, higher alcohol phosphate ester salts, and mixtures thereof.

[0143] The additive content can be arbitrarily adjusted to the extent that the effects of the present invention are not impaired. For example, it can be 0 to 5% by mass, preferably 0 to 1% by mass, more preferably 0 to 0.5% by mass, and even more preferably 0 to 0.2% by mass or less, relative to 100% by mass of the film of the present invention.

[0144] The biodegradable film of the second embodiment of the present invention may be a single-layer or multi-layer structure. In the case of a multi-layer structure, it may be a laminated film comprising layer a (core layer) and layers other than layer a (other layers). In the case of a multi-layer structure, it is preferable that layer a (core layer) contains polylactic acid, the aromatic phosphite ester compound of the present invention, and the aliphatic phosphite ester compound of the present invention.

[0145] Other layers include, for example, layer b formed of resin. That is, one embodiment of the biodegradable film of the second embodiment of the present invention includes layer b on one or both sides of layer a, wherein layer b contains, for example, a crystalline polyolefin resin having a melting point of 150 to 175°C. In this case, layer b can act as a so-called skin layer, making the biodegradable film smoother.

[0146] Layer b may be laminated by directly bonding it to layer a, or another layer may be interposed between layer a and layer b. From the viewpoint of reducing the haze of the biodegradable film of the second embodiment of the present invention, it is preferable that layer b is laminated by directly bonding it to layer a.

[0147] If layer b is formed on both sides of layer a, the layers b may be made of the same components, or they may be made of different components.

[0148] The method for forming layer a, the method for laminating layer b, etc., will be explained later in the section on the method for manufacturing a biodegradable film according to the second embodiment of the present invention.

[0149] The film of the present invention may also include layers other than layer b, either together with or in place of layer b. For example, a heat-seal layer may be included as a layer other than layer b. In other words, the biodegradable film of the second embodiment of the present invention may have a heat-seal layer on at least one side. This improves the heat-sealability of the biodegradable film. Here, the heat-seal layer refers to a layer other than the aforementioned layer b. Heat-sealability means that when heat-seal layers are overlapped facing each other and heat-pressed, they fuse together. Furthermore, other layers c may be laminated.

[0150] As described above, the biodegradable film of the second embodiment of the present invention may have layer a as a core layer, and optionally at least one layer selected from the group consisting of layer b, a heat seal layer, and layer c laminated to it. More specifically, the biodegradable film of the second embodiment of the present invention may include a laminate (i.e., b / a / b) in which layer a is used as a core layer and layer b is directly bonded to one or both sides thereof. Alternatively, the biodegradable film of the second embodiment of the present invention may include a laminate (i.e., b / a / heat seal layer, or b / a / c) in which layer a is used as a core layer, layer b is directly bonded to one side thereof, and a heat seal layer or layer c is bonded to the opposite side. Furthermore, the biodegradable film of the second embodiment of the present invention may include a laminate (i.e., heat seal layer / a / heat seal layer) in which layer a is used as a core layer and heat seal layers are directly bonded to both sides thereof. Furthermore, the biodegradable film of the second embodiment of the present invention may include a laminate (i.e., c / a / c) in which layer a is used as a core layer and layer c is directly bonded to both sides thereof. Moreover, the biodegradable film of the second embodiment of the present invention may include a laminate (i.e., heat-seal layer / a / c) in which layer a is used as a core layer, a heat-seal layer is directly bonded to one side thereof, and layer c is bonded to the opposite side.

[0151] The biodegradable film of the second embodiment of the present invention can be a stretched film in either a single-layer or multi-layer configuration. In the case of a stretched film, it is preferably a biaxially oriented film.

[0152] As described above, the biodegradable film of the second embodiment of the present invention includes the case of a multilayer structure, but the content of various components and biodegradability in the biodegradable film of the second embodiment of the present invention, as described later, refer to the content and characteristics in layer a (core layer) containing polylactic acid, the aromatic phosphite ester compound of the present invention, and the aliphatic phosphite ester compound of the present invention in the case of a multilayer structure.

[0153] The thickness of the biodegradable film of the second embodiment of the present invention is not particularly limited, but from the viewpoint of ensuring a certain level of strength, it is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 12 μm or more. From the viewpoint of transparency, the thickness is preferably 100 μm, more preferably 70 μm, even more preferably 50 μm or less, even more preferably 40 μm or less, particularly preferably 30 μm or less, and especially preferably 25 μm or less. When the biodegradable film of the second embodiment of the present invention has the multilayer structure described above, the thickness of the biodegradable film of the second embodiment of the present invention means the sum of the thicknesses of each layer. The thickness is measured by the method of the example (2-3-5) described below.

[0154] The phosphorus atom content in the biodegradable film of the second embodiment of the present invention is preferably 0.010 mmol / g or more. Among these, 0.020 mmol / g or more is more preferable, 0.025 mmol / g or more is even more preferable, and 0.030 mmol / g or more is particularly preferable. The upper limit of the phosphorus atom content in the biodegradable film of the second embodiment of the present invention is not particularly limited, but for example, it is 0.150 mmol / g, 0.100 mmol / g, 0.080 mmol / g, 0.060 mmol / g, 0.050 mmol / g, or 0.045 mmol / g.

[0155] The biodegradable film of the second embodiment of the present invention is biodegradable.

[0156] The film of the present invention is measured by the method (2-3-3) of the examples described below. ４８ / A ０ However, it is preferably 0.35 or less, more preferably 0.30 or less, even more preferably 0.25 or less, even more preferably 0.20 or less, particularly preferably 0.15 or less, and particularly more preferably 0.10 or less. The lower limit of this ratio is not particularly limited, but for example, it is 0.001, 0.002, or 0.005.

[0157] The biodegradable film of the second embodiment of the present invention has a period until disintegration, as measured by the method of the example (2-3-4) described below, preferably within two weeks, more preferably within one week.

[0158] The biodegradable film of the second embodiment of the present invention can be suitably used for heat-sealable bags, packaging, food packaging, pharmaceutical packaging, decoration (including fashion), labels, tape substrates, printing substrates, stationery, home appliances, poster paper, thermal paper substrates, recording paper substrates, interior and exterior applications for houses, automobiles, containers, and the like.

[0159] 2-2. Laminate using the biodegradable film of the second embodiment The film of the present invention is preferably used as a laminate having the film and a substrate. That is, the present invention also encompasses such laminates.

[0160] The biodegradable film and substrate of the second embodiment of the present invention can be bonded together by a known lamination process such as dry lamination or melt extrusion lamination, with an adhesive layer or adhesive resin layer between them, and surface treatment such as corona treatment as necessary.

[0161] Examples of suitable base materials include polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), polyvinyl chloride resins, fluororesins, poly(meth)acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resins such as various types of nylon, polyimide resins, polyamide-imide resins, polyarylphthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, polyurethane resins, acetal resins, cellulose resins, and various other resin films or sheets, paper, etc. Among these, polyethylene film and uniaxially oriented polypropylene (CPP) are preferred as base materials from the viewpoint of flexibility and heat sealability. It is preferable that the base material contains biomass plastic.

[0162] 2-3. Method for Manufacturing the Biodegradable Film of the Second Embodiment The method for manufacturing the biodegradable film of the second embodiment of the present invention is not particularly limited, and for example, known manufacturing methods can be widely employed. For example, the film of the present invention can be manufactured by extruding a resin raw material containing at least a biodegradable resin to obtain a resin sheet, and then stretching this resin sheet. Such a manufacturing method will be abbreviated as "Manufacturing Method A".

[0163] The resin raw materials used in manufacturing method A may include various additives as needed.

[0164] The method for preparing the resin raw material can be, for example, the same as known preparation methods, and includes methods such as dry blending resin pellets or powders using a batch-type mixing device such as a tumbler or mixer, or a continuous weighing-type mixing device; or supplying resin pellets or powders together with other resin pellets or powders and / or additives as needed to a kneader and melt-kneading to obtain a melt-blended resin composition. Among these, it is preferable to prepare the resin raw material by melt-kneading.

[0165] For the mixing process, any known mixing machine can be used, and a single-screw type, a twin-screw type, or a multi-screw type with more than one screw may be used. Furthermore, in the case of a twin-screw type with two or more screws, either a co-rotating or staggered rotation mixing type may be used. A twin-screw mixing machine with co-rotating screws is preferred because it facilitates the mixing of biodegradable resins.

[0166] The mixing temperature for melt mixing is preferably in the range of 170°C to 300°C, and more preferably in the range of 180°C to 240°C. To prevent deterioration of the resin during melt mixing, an inert gas such as nitrogen can be purged. The melt-mixed resin can be pelletized to an appropriate size using a generally known granulator to obtain melt-blend resin composition pellets.

[0167] In manufacturing method A, a resin sheet can be obtained using the resin raw material obtained as described above. Specifically, the resin raw material is supplied to an extruder, heated and melted, and if necessary, minute foreign matter is removed using a filter or the like. Then, the resin sheet can be obtained by melt-extruding it into a sheet shape from a T-die.

[0168] For obtaining the resin sheet, any known extruder can be widely used. There are no restrictions on the screw type of the extruder; a single-screw type, a twin-screw type, or a multi-screw type with more than one screw may be used. When the resin raw material is prepared using the dry blend described above, using a twin-screw type or a multi-screw type with more than one screw tends to provide better mixing and dispersibility. The extrusion temperature is preferably in the range of 170°C to 300°C, and more preferably in the range of 180°C to 240°C. To prevent thermal degradation of the resin during extrusion, purging with an inert gas such as nitrogen can be performed.

[0169] The melt-extruded resin sheet is formed into a sheet shape by known methods, such as by pressing it onto at least one metal drum set to a temperature of 25 to 120°C using an air knife, other rolls, or static electricity, and the resin sheet is obtained as a so-called raw material sheet. A more preferred temperature for the metal drum is 30 to 80°C, and an even more preferred temperature is 40 to 60°C.

[0170] Manufacturing method A may further include a lamination process as needed.

[0171] In the lamination process, conventional lamination methods can be widely used, for example, films obtained by lamination using methods such as co-extrusion, lamination, and heat sealing.

[0172] Specifically, when manufacturing a stretched film having a laminated structure, a resin sheet having a laminated structure can be obtained by co-extruding two or more dry blend and / or melt blend resin compositions (the composition of each resin composition may be different or the same), and then stretching such a resin sheet having a laminated structure. Alternatively, a stretched film having a laminated structure can also be manufactured by laminating a single-layer stretched film with another film. Furthermore, a stretched film having a laminated structure can also be manufactured by stretching a multilayer unstretched film (the composition of the resin composition constituting each layer may be different or the same) obtained by laminating two or more unstretched films extruded as single layers together.

[0173] Examples of the aforementioned co-extrusion methods include pre-die lamination, in which the molten resin is brought into contact within a feed block in front of the mold; in-die lamination, in which contact occurs within a path inside the mold, such as a multi-manifold die; and off-die lamination, in which the molten resin is extruded and brought into contact from multiple concentric lips. For example, in the in-die lamination method, a multilayer die such as a three-layer multi-manifold die can be used to create a three-layer structure consisting of a surface layer (heat seal layer) and a core layer (substrate layer), such as a heat seal layer / substrate layer / heat seal layer.

[0174] Lamination methods include the extrusion lamination method, which uses the equipment for the molten extrusion molding method used in the T-die method to directly extrude a film of molten resin onto another film to form the film.

[0175] Heat sealing methods include external heating methods, in which a heated metal object is pressed against multiple films to be bonded together from the outside of the films, and the conducted heat melts and bonds the films, and internal heating methods, in which heat is generated in the films using high-frequency radio waves or ultrasound to bond them.

[0176] In manufacturing method A, the above lamination methods can be used individually or in combination as needed.

[0177] In manufacturing method A, the resin sheet (raw material sheet) having the single-layer or laminated structure described above is stretched. As for the stretching method, known methods such as stretching between rolls with a difference in peripheral speed, the tenter method, and the tubular method can be used. As for the stretching direction, uniaxial stretching, biaxial stretching, and diagonal biaxial stretching are possible, and for stretching in two or more axes, both sequential stretching and simultaneous stretching are applicable. Of these, the simultaneous biaxial stretching method using the tenter method, the sequential biaxial stretching method using the tenter method, and the sequential biaxial stretching method in which the longitudinal (flow, MD) stretching is performed between rolls with a difference in peripheral speed, followed by transverse (width, TD) stretching using the tenter method are preferred because they make it easier to obtain the desired biaxially oriented film. The following describes a method for obtaining the film of the present invention by the sequential biaxial stretching method, but is not limited thereto.

[0178] In the sequential biaxial stretching method, it is preferable to adjust the stretching temperature and stretching ratio according to the melting point and glass transition temperature of the resin used. First, the resin sheet (raw material sheet) is kept at a temperature of preferably 40 to 120°C, more preferably 50 to 100°C, and even more preferably 60 to 90°C, and stretched in the longitudinal direction by preferably 1.5 to 4 times, more preferably 1.8 to 2.5 times, by passing it between rolls with a difference in peripheral speed, or by the tenter method. Subsequently, the stretched film is stretched in the transverse direction by preferably 2 to 5 times, more preferably 2.5 to 4 times, at a temperature of preferably 40 to 120°C, more preferably 50 to 100°C, and even more preferably 60 to 90°C, using the tenter method. After that, the film is subjected to a heat treatment, which includes a relaxation treatment and a heat setting treatment, before being wound up. The wound film can be aged in an atmosphere of preferably 20 to 45°C, and then cut to the desired product width.

[0179] The relaxation rate is preferably 1 to 4%, more preferably 1.5 to 3%. The heat-fixing temperature is preferably 120°C to 160°C, more preferably 130 to 150°C.

[0180] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to the embodiments of these examples. Unless otherwise specified, "parts" and "%" refer to "parts by mass" and "mass%", respectively.

[0181] (Examples of the First Embodiment) Hereinafter, examples of the first embodiment of the present invention will be described.

[0182] The resin (polylactic acid), phosphite ester compound, particles, and physical property measurement methods used in the examples and comparative examples of the first embodiment of the present invention are as follows.

[0183] (Polylactic acid) ・Resin B: Luminy® LX175 (manufactured by Total Corbion PLA, polylactic acid, D-isomer 4 mol%)

[0184] (Phosphite ester compounds) - Compound 1-1 represented by the following formula (I-II) (ADEKA "PEP-36", molecular weight 633, number of phosphorus atoms in the molecule 2, number of aromatic rings in the molecule 2)

[0185]

[0186] Compounds 1-2 represented by the following formula (I-III) (Tokyo Chemical Industries, Ltd., "Pentaerythritol bis(2,4-di-tert-butylphenyl phosphite), CAS: 26741-53-7", molecular weight 605, number of phosphorus atoms in the molecule 2, number of aromatic rings in the molecule 2)

[0187]

[0188] Compounds 1-3 represented by the following formulas (I-IV) (Merck's "3,9-Bis(2,4-dicumylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, CAS: 154862-43-8", molecular weight 853, number of phosphorus atoms in the molecule 2, number of aromatic rings in the molecule 6)

[0189]

[0190] Compounds 1-4 represented by the following formulas (I-V) (ADEKA's "PEP-8", molecular weight 733, number of phosphorus atoms in the molecule 2, comparative product)

[0191]

[0192] Compounds 1-5 represented by the following formula (I-VI) (ADEKA's "HP-10", molecular weight 583, number of phosphorus atoms in the molecule 1, number of aromatic rings in the molecule 2, comparative product)

[0193]

[0194] Compounds 1-6 represented by the following formulas (I-VII) (ADEKA "2112RG", molecular weight 647, number of phosphorus atoms in the molecule 1, number of aromatic rings in the molecule 3, comparative product)

[0195]

[0196] Compounds 1-7 represented by the following formula (I-VII) (JP318E, manufactured by Johoku Chemical Industry Co., Ltd., molecular weight 838, number of phosphorus atoms in the molecule 1, number of aromatic rings in the molecule 0, comparative product)

[0197]

[0198] (Antiblocking agents (AB agents)) - Acrylic AB agent 1-1 ("Epostor MV1002" manufactured by Nippon Shokubai Co., Ltd.) - Silica AB agent 1-1 ("Silohobic 100" manufactured by Fuji Silicia Chemical Co., Ltd.) - Silica AB agent 1-2 ("KE-P100" manufactured by Nippon Shokubai Co., Ltd.)

[0199] [Phosphorus content in biodegradable film] A 100 g sample of biodegradable film was added to a mixture of 5 ml of nitric acid and 1 ml of hydrogen peroxide, and pressurized acid decomposition was performed using a decomposition device (Milestone General "ETOS UP"), after which the volume was reduced to 20 ml. The phosphorus atom concentration [mol / g] of the solution after decomposition was measured using an ICP device (Rigaku "CIROS120").

[0200] [Contamination of the film-forming equipment] The presence or absence of contamination of the cooling drum after film formation of biodegradable film was evaluated visually. The evaluation criteria were as follows: A: No white powder adheres to the cooling drum after 1 hour of film formation. B: White powder adheres to the cooling drum after 1 hour of film formation.

[0201] [Biodegradability of Biodegradable Films] - Evaluation based on the ratio of elongation at break The elongation at break A of the biodegradable film at the time of specimen preparation is measured according to the following measurement conditions (I). ０ The elongation at break A of the test specimen after 48 hours of constant temperature and humidity treatment, measured according to the following measurement conditions (II): ４８ Ratio A ４８ / A ０The following evaluation was performed. <Measurement conditions (I)> A test piece (15 mm wide, 170 mm long) was cut from the biodegradable film and subjected to a tensile test using a Tensilon universal testing machine (Orientec Co., Ltd., model number RTG-1210) at a tensile speed of 200 mm / min and a chuck distance of 100 mm, and the elongation at break (%) was measured (A ０ ). <Measurement conditions (II)> The above test piece is cut separately from the same film, left to stand for 48 hours in a constant temperature and humidity chamber set to 60°C and 95% humidity, and then subjected to the above tensile test and the elongation at break (%) is measured (A ４８ ). However, under measurement condition (II), the elongation at break of the film that breaks before being subjected to the tensile test described above shall be 0%. ・Evaluation based on biodegradability test A test piece (100 mm wide, 100 mm long) is cut from the biodegradable film, buried in leaf litter, and left to stand in a constant temperature and humidity chamber set to 58°C and 95% humidity. The evaluation is based on the time it takes for the test piece to disintegrate. In Table 1 below, "-" indicates that the test piece has "disintegrated," meaning that the test piece cannot maintain its shape when lifted by hand.

[0202] [Film Thickness] The thickness of the biodegradable films obtained in each example and comparative example was measured in accordance with JIS-C2330 (2024) using the Citizen Seimitsu Co., Ltd. paper thickness measuring instrument "MEI-11".

[0203] (Example 1-1) 100 parts by mass of LX-175 (manufactured by Total Corbion) as polylactic acid, 1.0 part by mass of compound 1-1 as a phosphite ester compound, and 0.1 parts by mass of an acrylic AB agent as an antiblocking agent were dry blended, and the mixture was put into a screw-type extruder hopper and melted, and then extruded from a single-layer die. After obtaining a raw material sheet from the extruded resin layer on a cooling drum controlled to 50°C, it was subjected to a stretching treatment. The stretching treatment was performed at a stretching temperature of 75°C, stretching 2.10 times in the MD direction and 3.75 times in the TD direction. The heat-fixing temperature after stretching was 140°C, the relaxation rate was 2%, and a biodegradable film (stretched film) with a thickness of 20 μm was obtained.

[0204] (Examples 1-2 to 1-5, Comparative Examples 1-1 to 1-5) Biodegradable films (stretched films) were obtained in the same manner as in Example 1-1, except that the types of phosphite ester compounds and AB agents were changed as shown in Table 1-1.

[0205] Table 1-1 shows the production conditions and evaluation results for the biodegradable films obtained in each example and comparative example. The biodegradable films of the present invention (Examples 1-1 to 1-5) containing (A) polylactic acid and (B) a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule exhibit good hydrolysis (biodegradability) and suppress contamination of the film-making equipment. On the other hand, Comparative Example 1-1, which used the phosphite ester compound 1-4, which has two phosphorus atoms in one molecule but no aromatic ring, and Comparative Example 1-5, which used the phosphite ester compound 1-7, which has one phosphorus atom in one molecule and no aromatic ring, both exhibited low heat resistance of the phosphite ester compound due to the lack of an aromatic ring, and contamination of the film-making equipment was observed. Furthermore, in Comparative Examples 3 and 4, which used phosphite ester compounds 1-5 and 1-6, which have an aromatic ring in one molecule but contain only one phosphorus atom per molecule, the phosphite ester compounds had little to no ability to hydrolyze polylactic acid, resulting in the same hydrolytic properties (biodegradability) as Comparative Example 1-2, which did not contain phosphite ester compounds. In other words, although no contamination of the film-forming equipment was observed in the films of Comparative Examples 1-2 to 1-4, the films did not possess the required biodegradability.

[0206] (Example of the second embodiment) The following describes an example of the second embodiment of the present invention.

[0207] (2-1) Materials The resin (polylactic acid), phosphite ester compound, and particles used in the examples and comparative examples of the second embodiment of the present invention are as follows.

[0208] (2-1-1) Polylactic acid resin B: Luminy® LX175 (manufactured by Total Corbion PLA, polylactic acid, D-isomer 4 mol%).

[0209] (2-1-2) Phosphite ester compounds - Compound 2-1 represented by the following formula (2-1) (ADEKA "PEP-36", molecular weight 633, number of phosphorus atoms in the molecule 2, number of aromatic rings in the molecule 2, melting point 234-240°C).

[0210]

[0211] Compound 2-2, represented by the following formula (2-2) (Tokyo Chemical Industries, Ltd., "Pentaerythritol bis(2,4-di-tert-butylphenyl phosphite), CAS: 26741-53-7", molecular weight 605, number of phosphorus atoms in the molecule 2, number of aromatic rings in the molecule 2, melting point 175-179°C).

[0212]

[0213] Compound 2-3, represented by the following formula (2-3) (Merck's "3,9-Bis(2,4-dicumylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, CAS: 154862-43-8", molecular weight 853, number of phosphorus atoms in the molecule 2, number of aromatic rings in the molecule 6, melting point 229-232°C).

[0214]

[0215] Compound 2-4, represented by the following formula (2-4) (ADEKA Corporation's "PEP-8", molecular weight 733, number of phosphorus atoms in the molecule 2, melting point 50-62°C).

[0216]

[0217] Compound 2-5, represented by the following formula (2-5) (JPH3800, manufactured by Johoku Chemical Co., Ltd., number-average molecular weight 2000, number of phosphorus atoms in the molecule 9.2, melting point 90°C).

[0218]

[0219] (2-1-3) Antiblocking agents (AB agents) - Silica-based AB agent 2-1 (KE-P100 manufactured by Nippon Shokubai Co., Ltd.) - Acrylic-based AB agent 2-1 (Epostor MV1002 manufactured by Nippon Shokubai Co., Ltd.).

[0220] (2-2) Film Production (Example 2-1) 100 parts by mass of LX-175 (manufactured by Total Corbion) as polylactic acid, 1.0 part by mass of compound 2-1 as an aromatic phosphite ester compound, 0.2 parts by mass of compound 2-4 as an aliphatic phosphite ester compound, and 0.1 parts by mass of silica-based AB agent as an antiblocking agent were dry blended and put into a screw-type extruder hopper to melt, and extruded from a single-layer die. After obtaining a raw material sheet from the extruded resin layer on a cooling drum controlled to 50°C, it was subjected to a stretching treatment. The stretching treatment was performed at a stretching temperature of 75°C, stretching 2.10 times in the MD direction and 3.75 times in the TD direction. The heat-fixing temperature after stretching was 140°C, the relaxation rate was 2%, and a biodegradable film (stretched film) with a thickness of 20 μm was obtained.

[0221] (Examples 2-2 to 2-7, Reference Examples 2-1 to 2-3, Comparative Example 2-1) As shown in Table 2-1, a biodegradable film (stretched film) with a thickness of 20 μm was obtained in the same manner as in Example 2-1, except that at least one selected from the group consisting of the type of phosphite ester compound, the content of the phosphite ester compound, and the type of AB agent was changed.

[0222] (2-3) Measurement and evaluation of physical properties (2-3-1) Measurement of phosphorus atom content in biodegradable film A sample of biodegradable film, 100 g, was added to a mixture of 5 ml of nitric acid and 1 ml of hydrogen peroxide, and pressurized acid decomposition was carried out using a decomposition device (ETOS UP, manufactured by Milestone General Co., Ltd.), and the volume was adjusted to 20 ml after decomposition. The phosphorus atom concentration [mol / g] of the solution after decomposition was measured using an ICP device (CIROS120, manufactured by Rigaku Corporation).

[0223] (2-3-2) Presence or absence of contamination of the film-forming equipment The presence or absence of contamination of the cooling drum after film formation of biodegradable film was evaluated by visual inspection. The evaluation criteria were as follows: A: No white powder adheres to the cooling drum after 1 hour of film formation. B: A small amount of white powder adheres to the cooling drum after 1 hour of film formation. C: White powder adheres to the cooling drum after 1 hour of film formation.

[0224] (2-3-3) Evaluation of the biodegradability of biodegradable films 1 (Evaluation based on the ratio of elongation at break) Elongation at break A of the biodegradable film at the time of specimen preparation, measured according to the following measurement conditions (I) ０ The fracture elongation A of the test specimen after 48 hours of high-temperature constant humidity treatment, measured according to the following measurement conditions (II). ４８ Ratio A ４８ / A ０ It was evaluated by [method / method].

[0225] <Measurement Conditions (I)> A test piece (15 mm wide, 170 mm long) is cut from the biodegradable film and subjected to a tensile test using a Tensilon universal testing machine (Orientec Co., Ltd., model number RTG-1210) at a tensile speed of 200 mm / min and a chuck distance of 100 mm, and the elongation at break (%) is measured (A ０ ).

[0226] <Measurement Conditions (II)> The above test piece is cut separately from the same film, left to stand for 48 hours in a constant temperature and humidity chamber set to 60°C and 95% humidity, and then subjected to the above tensile test, and the elongation at break (%) is measured (A ４８ ).

[0227] However, under measurement condition (II), the elongation at break of the film that breaks before being subjected to the tensile test described above shall be 0%.

[0228] (2-3-4) Evaluation of the biodegradability of biodegradable film 2 (Evaluation based on biodegradability test) A test piece (100 mm wide, 100 mm long) was cut from the biodegradable film, buried in leaf mold, and left to stand in a constant temperature and humidity chamber set to 58°C and 95% humidity. The evaluation was based on the time it took for the test piece to disintegrate. "Disintegration" of the test piece means that the test piece can no longer maintain its shape when lifted by hand.

[0229] (2-3-5) Film Thickness The thickness of the biodegradable film was measured in accordance with JIS-C2330 (2024) using the MEI-11 paper thickness measuring instrument manufactured by Citizen Seimitsu Co., Ltd.

[0230] (2-4) Results The results are shown in Table 2-1.

[0231]

Claims

1. A biodegradable film characterized by containing (A) polylactic acid and (B) a phosphite ester compound having two or more phosphorus atoms and one or more aromatic rings in one molecule.

2. The elongation at break A of the biodegradable film at the time of test specimen preparation, measured according to the following measurement conditions (I). ０ The elongation at break A of the test specimen after 48 hours of constant temperature and humidity treatment, measured according to the following measurement conditions (II): ４８ Ratio A ４８ / A ０ The biodegradable film according to claim 1, wherein the ratio is 0.8 or less; <Measurement conditions (I)> A test piece (15 mm wide, 170 mm long) is cut from the biodegradable film and subjected to a tensile test using a Tensilon universal tester (Orientec Co., Ltd. "Model RTG-1210") at a tensile speed of 200 mm / min and a chuck distance of 100 mm, and the elongation at break (%) is measured (A ０ ). <Measurement conditions (II)> The above test piece is cut separately from the same film, left to stand for 48 hours in a constant temperature and humidity chamber set to 60°C and 95% humidity, and then subjected to the above tensile test and the elongation at break (%) is measured (A ４８ ). However, under measurement condition (II), the elongation at break of the film that breaks before being subjected to the tensile test described above shall be 0%.

3. The biodegradable film according to claim 1, wherein the phosphorus atom content in the biodegradable film is 0.01 mmol / g or more.

4. The biodegradable film according to claim 1, wherein the phosphite ester compound has two phosphite ester structures in one molecule.

5. The phosphite ester compound has the following formula (I-I): [However, R １ and R ２ The biodegradable film according to claim 1, represented by [ ] is a hydrocarbon group having the same or different aromatic rings.

6. The biodegradable film according to claim 1, wherein the biodegradable film is a stretched film.

7. A laminate comprising a biodegradable film according to any one of claims 1 to 6 and a substrate.

8. A biodegradable film containing (A) polylactic acid, (B) an aromatic phosphite ester compound having two or more phosphorus atoms in one molecule, and (C) an aliphatic phosphite ester compound having two or more phosphorus atoms in one molecule.

9. The aromatic phosphite compound and the aliphatic phosphite compound are of formula (II-I): The biodegradable film according to claim 8, having the substructure shown by [the symbol].

10. The biodegradable film according to claim 8, wherein the number of phosphorus atoms in the molecules of the aromatic phosphite compound and the aliphatic phosphite compound is 2 to 10.

11. The biodegradable film according to claim 8, wherein the molecular weights of the aromatic phosphite compound and the aliphatic phosphite compound are 300 to 3000.

12. The biodegradable film according to claim 8, wherein the content of the aromatic phosphite ester compound is 0.3 to 5.0 parts by mass per 100 parts by mass of the polylactic acid.

13. The biodegradable film according to claim 8, wherein the content of the aliphatic phosphite ester compound is 0.01 to 0.5 parts by mass per 100 parts by mass of polylactic acid.

14. The biodegradable film according to claim 8, wherein the phosphorus atom content is 0.010 mmol / g or more.

15. The biodegradable film according to claim 8, which is a stretched film.

16. A laminate comprising a biodegradable film according to any one of claims 8 to 15 and a substrate.

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