Thermoplastic polyolefin film

Abstract

To provide a thermoplastic polyolefin film having easy tearability, and superior heat resistance and thermal moldability.SOLUTION: A thermoplastic polyolefin film is composed of a resin composition comprising thermoplastic polyolefin as a main component, wherein, the elongation at break in the MD direction is 10.0% or more, the ratio [MD / TD] of the elongation at break in the MD direction to that in the TD direction is 2.0 to 30.0, and the storage elastic modulus E' at 270°C is 1 MPa or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a thermoplastic polyolefin film.

Background Art

[0002] Thermoplastic polyolefins such as polyethylene and polypropylene are suitable for extrusion-molded products and injection-molded products such as film products, and films formed from thermoplastic polyolefins are widely and commonly used. However, general thermoplastic polyolefins such as polyethylene and polypropylene are not suitable for use in higher temperature environments, for example, exceeding 200°C. Therefore, development of plastic films formed from thermoplastic polyolefins that can be used even in higher temperature environments has been underway. For example, Patent Document 1 discloses an unstretched film formed from a homopolymer of 3-methylbutene-1 or a copolymer of 3-methylbutene-1 and an α-olefin and / or polyene having 2 to 12 carbon atoms, having a melt viscosity measured under the conditions of 330°C and a shear rate of 0.1 (1 / sec) of 1×10 4 poise or more, and a stretched film obtained by stretching the unstretched film at a stretching ratio of 2 times or more. Further, Patent Document 3 discloses a uniaxially stretched film formed from a composition containing 5 to 95 parts by weight of a 3-methyl-1-butene polymer (A) and 5 to 95 parts by weight of a 4-methyl-1-pentene polymer (B) [the total amount of component (A) and component (B) is 100 parts by weight.], and a release film characterized in that at least one surface of the uniaxially stretched film is roughened by embossing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, in order to enable use in a higher temperature environment, better heat resistance is required for films formed from thermoplastic polyolefins. Also, for example, thermoforming films used in compression molding, pressure air molding, vacuum molding, etc.; release films for semiconductor encapsulation processes, etc., it is necessary to press or suck the film against a mold while heating the film during molding of the molded product, etc., and make the film follow the mold shape. Therefore, it is required to suppress breakage and damage, etc. even under high temperature and pressure conditions, and to have good mold formability. Therefore, from the perspective of being expected to be developed for such applications, etc., better thermoformability is also required for films formed from thermoplastic polyolefins. Also, for example, plastic films are also used as food packaging materials, pharmaceutical packaging materials, general merchandise packaging materials, adhesive tapes, etc. Therefore, from the perspective of being expected to be developed for such applications, etc., good tearability may be required for films formed from thermoplastic polyolefins. Therefore, an object of the present invention is to provide a thermoplastic polyolefin-based film having good tearability, heat resistance, and thermoformability.

Means for Solving the Problems

[0005] As a result of intensive research, the present inventors have found that the above problems can be solved by using a thermoplastic polyolefin-based film that satisfies specific requirements. That is, the present invention includes the following inventions. [1] A thermoplastic polyolefin-based film formed from a resin composition containing a thermoplastic polyolefin as a main component, having an elongation at break in the MD direction of 10.0% or more, a ratio of the elongation at break in the MD direction to the elongation at break in the TD direction [MD / TD] of 2.0 to 30.0, and a storage elastic modulus E' at 270°C of 1 MPa or more. [2] The thermoplastic polyolefin film according to [1] above, wherein the storage elastic modulus E' at 70 °C is 1,000 MPa or less. [3] The thermoplastic polyolefin film according to [1] or [2] above, wherein the storage elastic modulus E' at 150 °C is 50 to 500 MPa. [4] The thermoplastic polyolefin film according to any one of [1] to [3] above, wherein the storage elastic modulus E' at 270 °C is 1 to 100 MPa. [5] The thermoplastic polyolefin film according to [2] above, wherein the storage elastic modulus E' at 70 °C is 100 to 1,000 MPa. [6] The thermoplastic polyolefin film according to any one of [1] to [5] above, wherein the yellowness index (YI) is 3.50 or less. [7] The thermoplastic polyolefin film according to any one of [1] to [6] above, wherein the thermoplastic polyolefin is an aliphatic polyolefin. [8] The thermoplastic polyolefin film according to any one of [1] to [7] above, wherein the thermoplastic polyolefin is a 3-methyl-1-butene-based polymer. [9] The thermoplastic polyolefin film according to [8] above, wherein the 3-methyl-1-butene-based polymer is at least one selected from the group consisting of a 3-methyl-1-butene homopolymer and at least one copolymer composed of 3-methyl-1-butene and at least one selected from the group consisting of ethylene and an α-olefin having 3 to 20 carbon atoms other than 3-methyl-1-butene.

[10] The thermoplastic polyolefin film according to [8] or [9] above, wherein the content of the 3-methyl-1-butene-based polymer is 50.0 mass% or more in 100 mass% of the total amount of the resin composition.

[11] The thermoplastic polyolefin film according to any one of [1] to

[10] above, wherein the resin composition contains an antioxidant.

[12] The thermoplastic polyolefin film according to

[11] above, wherein the antioxidant is at least one selected from the group consisting of a phenolic antioxidant and a phosphorus-based antioxidant.

[13] including a step (I) of melt-extruding a resin composition containing a thermoplastic polyolefin as a main component, a method for producing a thermoplastic polyolefin-based film, which produces a thermoplastic polyolefin-based film having an elongation at break in the MD direction of 10.0% or more, a ratio [MD / TD] of the elongation at break in the MD direction to the elongation at break in the TD direction of 2.0 to 30.0, and a storage elastic modulus E' at 270 °C of 1 MPa or more.

[14] The method for producing a thermoplastic polyolefin-based film according to

[13] above, wherein during step (I), the resin composition containing the thermoplastic polyolefin as a main component is melted under an inert atmosphere or in a low oxygen state.

[15] The method for producing a thermoplastic polyolefin-based film according to

[13] or

[14] above, wherein during step (I), the resin composition containing the thermoplastic polyolefin as a main component is melted at 280 to 323 °C.

[16] including a step (II) of bringing the melt-extruded product of the resin composition containing the thermoplastic polyolefin as a main component obtained in step (I) into contact with a casting drum, and the temperature of the casting drum is 40 to 250 °C, the method for producing a thermoplastic polyolefin-based film according to any one of

[13] to

[15] above.

[17] During the step (I), the melt of the resin composition containing the thermoplastic polyolefin as a main component is extruded through a T-die, and the draft ratio [Tt / Ft], which is the ratio of the gap thickness (Tt) of the lip portion of the T-die to the thickness (Ft) of the obtained thermoplastic polyolefin-based film, is 1 to 30, the method for producing a thermoplastic polyolefin-based film according to any one of

[13] to

[16] above.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a thermoplastic polyolefin-based film having easy tearability, good heat resistance, and good thermoformability.

Embodiments for Carrying Out the Invention

[0007] Hereinafter, an example of an embodiment of the present invention (hereinafter also referred to as "one aspect of the present invention") will be described. However, each of the embodiments shown below is an exemplification for embodying the technical idea of the present invention, and the present invention is not limited to the following description. Aspects arbitrarily selected from the matters described in this specification or aspects arbitrarily combined are also included in the present invention. In this specification, although preferred forms of the embodiments are shown, those obtained by combining two or more of the individual preferred forms are also preferred forms. The stipulation of being preferred can be arbitrarily selected. For example, it can be said that a combination of the stipulations of being preferred is more preferred. In this specification, unless otherwise specified, the description of "XX to YY" as a numerical range means "XX or more and YY or less" (XX represents the lower limit value and YY represents the upper limit value). For example, when simply described as "10 to 90" as a numerical range, it represents a range of 10 or more and 90 or less. In this specification, for numerical ranges (each characteristic value, each component content, each structural unit content, each manufacturing condition, and values calculated therefrom, each characteristic, and each condition, etc.), the lower limit value and the upper limit value described stepwise can be combined independently of each other. For example, from the description of "preferably 10 to 90, more preferably 30 to 60" for the same matter, it is also possible to combine the "preferred lower limit value (10)" and the "more preferred upper limit value (60)" to obtain "10 to 60". Also, for a numerical range, for example, based on the description of "preferably 10 to 90, more preferably 30 to 60", the upper limit value can be specified only on the lower limit side as "10 or more" or "30 or more" without particularly specifying the upper limit value. Similarly, the lower limit value can be specified only on the upper limit side as "90 or less" or "60 or less" without particularly specifying the lower limit value. The same applies when the upper end of the numerical range is "less than" or the lower limit is "more than". Similarly, for example, from the descriptions of "preferably 10 or more, more preferably 30 or more" and "preferably 90 or less, more preferably 60 or less" for the same matter, it is also possible to combine the "preferred lower limit value (10)" and the "more preferred upper limit value (60)" to obtain "10 or more and 60 or less". Similarly, only the lower limit side can be defined as "10 or more" or "30 or more", and similarly, only the upper limit side can be defined as "90 or less" or "60 or less". Also, the same applies when the descriptions of "or more" and "or less" in the above description are respectively described as "exceeding" and "less than". That is, for example, based on the description of "preferably exceeding 10 and less than 90, more preferably 30 or more and 60 or less", it is also possible to combine the respective upper and lower limits to obtain "exceeding 10 and 60 or less", "30 or more and less than 90". In addition, in this specification, unless otherwise specified, the notations of "storage elastic modulus E'", "planarity (property evaluated by 'curl degree')", "yellowness index (YI)", "elongation at break point", "ease of tearing", "heat resistance", and "thermoformability" refer to the properties of the thermoplastic polyolefin film which is one aspect of the present invention. Also, these properties are specifically the properties measured and evaluated by the methods described in the examples respectively. In addition, in this specification, "ease of tearing" refers to the property that can be torn by human hands. Also, ease of tearing is only one of the properties of the thermoplastic polyolefin film which is one aspect of the present invention. Therefore, the thermoplastic polyolefin film is suitable for applications where ease of tearing is required, but thereby, the applications of the thermoplastic polyolefin film are not limited to applications where ease of tearing is required.

[0008] [Thermoplastic Polyolefin Film] A thermoplastic polyolefin-based film (hereinafter also abbreviated as "TPO-based film"), which is one aspect of the present invention, is formed from a resin composition containing a thermoplastic polyolefin as a main component (hereinafter also abbreviated as "the resin composition"), has an elongation at break in the MD direction of 10.0% or more, a ratio of the elongation at break in the MD direction to the elongation at break in the TD direction [MD / TD] of 2.0 to 30.0, and a storage modulus E' at 270 °C of 1 MPa or more. By satisfying the respective ranges of the elongation at break in the MD direction and the ratio [MD / TD] of the elongation at break, the TPO-based film can have easy tearability. Further, by satisfying the range of the storage modulus E', the TPO-based film can have good heat resistance and thermoformability. In addition, in this specification, "thermoplastic polyolefin-based film" refers to a film formed from a resin composition containing the thermoplastic polyolefin as a main component. For example, it also includes a thermoplastic polyolefin film formed when the resin composition consists of only a single thermoplastic polyolefin. In addition, in this specification, "contained as a main component" means contained as the component having the highest content on a mass basis in the resin composition.

[0009] From the viewpoint of better easy tearability, the elongation at break in the MD direction is preferably 40.0% or more, more preferably 70.0% or more, still more preferably 80.0% or more, and even more preferably 130.0% or more. Also, the elongation at break in the MD direction may be, for example, 300.0% or less, 250.0% or less, or 225.0% or less. As described above, the lower limit values and upper limit values described stepwise can be combined independently. For example, as one aspect of the TPO-based film, the elongation at break in the MD direction may be, for example, 10.0 to 300.0%, 40.0 to 300.0%, 70.0 to 300.0%, 80.0 to 300.0%, 130.0 to 300.0%, 10.0 to 250.0%, 40.0 to 250.0%, 70.0 to 250.0%, 80.0 to 250.0%, 130.0 to 250.0%, 10.0 to 225.0%, 40.0 to 225.0%, 70.0 to 225.0%, 80.0 to 225.0%, or 130.0 to 225.0%.

[0010] From the viewpoint of better tearability, the ratio of the elongation at break [MD / TD] is preferably 3.0 or more, more preferably 5.0 or more, still more preferably 6.5 or more, and even more preferably 8.0 or more. Also, from the viewpoint that the handling property during film formation and post-processing of the film becomes good, the ratio of the elongation at break [MD / TD] is preferably 32.0 or less, more preferably 28.0 or less, still more preferably 24.0 or less, and even more preferably 20.0 or less. As described above, the lower limit values and upper limit values described stepwise can be combined independently. For example, as one aspect of the TPO-based film, the ratio of the elongation at break [MD / TD] is preferably 3.0 to 32.0, more preferably 5.0 to 28.0%, still more preferably 6.5 to 24.0, and even more preferably 8.0 to 20.0.

[0011] From the viewpoint of better heat resistance, the storage elastic modulus E' at 150 °C is preferably 50 MPa or more, more preferably 70 MPa or more, still more preferably 100 MPa or more, and from the viewpoint of better heat resistance and thermoformability, even more preferably 120 MPa or more, and even more preferably 140 MPa or more. By being above the lower limit value, the thermoformability becomes better. Specifically, it is preferable because wrinkles due to drawdown of the film during thermoforming can be suppressed, and defects such as thickness unevenness of the obtained molded body can be suppressed. Also, from the viewpoints of preventing film breakage during thermoforming and easily maintaining formability with respect to a mold having a complex shape, the storage elastic modulus E' at 150°C is preferably 500 MPa or less, and may be, for example, 400 MPa or less, or 300 MPa or less. As described above, these stepwise-described lower limit values and upper limit values can be combined independently. For example, as one aspect of the TPO-based film, the storage elastic modulus E' at 150°C is preferably 50 to 500 MPa, more preferably 70 to 500 MPa, still more preferably 100 to 500 MPa, even more preferably 120 to 500 MPa, even more preferably 140 to 500 MPa, and may also be 50 to 400 MPa, 70 to 400 MPa, 100 to 400 MPa, 120 to 400 MPa, 140 to 400 MPa, 50 to 300 MPa, 70 to 300 MPa, 100 to 300 MPa, 120 to 300 MPa, or 140 to 300 MPa. When the thermoplastic polyolefin is a 3-methyl-1-butene-based polymer, the higher the storage elastic modulus E' at 150°C, the more likely the values of the elongation at break in the MD direction and the ratio [MD / TD] of the elongation at break are to be larger.

[0012] From the viewpoint of better heat resistance, the storage elastic modulus E' at 270°C is preferably 5 MPa or more, more preferably 10 MPa or more, and from the viewpoints of better heat resistance and thermoformability, still more preferably 20 MPa or more, even more preferably 25 MPa or more. Also, the storage elastic modulus E' at 270°C is preferably 100 MPa or less, and may also be 80 MPa or less. As described above, the lower and upper limits described stepwise can be combined independently of each other. For example, as one aspect of the TPO-based film, the storage elastic modulus E' at 270°C is preferably 1 to 100 MPa, more preferably 5 to 100 MPa, still more preferably 10 to 100 MPa, even more preferably 20 to 100 MPa, and even more preferably 25 to 100 MPa, and may also be 1 to 80 MPa, 5 to 80 MPa, 10 to 80 MPa, 20 to 80 MPa, or 25 to 100 MPa. Further, when the thermoplastic polyolefin is a 3-methyl-1-butene polymer, the higher the storage elastic modulus E' at 270°C, the more likely the values of the elongation at break in the MD direction and the ratio of the elongation at break [MD / TD] will be larger.

[0013] The storage elastic modulus E' of the TPO-based film at 70°C is preferably 1,000 MPa or less, more preferably 900 MPa or less, still more preferably 800 MPa or less, and even more preferably 700 MPa or less. By being below the upper limit value, for example, the film becomes more flexible, and it is possible to prevent the film from cracking during film conveyance during post-processing, etc., so the handling property of the film becomes better, which is preferable. Further, from the viewpoint of better heat resistance and better storage stability of the film even in a higher temperature environment, the storage elastic modulus E' of the TPO-based film at 70°C is preferably 100 MPa or more, more preferably 250 MPa or more, still more preferably 300 MPa or more, and even more preferably 350 MPa or more, and even more preferably 400 MPa or more from the viewpoint of better heat resistance and thermoformability. As described above, the lower and upper limits described stepwise can be combined independently of each other. For example, as one aspect of the TPO-based film, the storage elastic modulus E' at 70°C is preferably 100 to 1,000 MPa, more preferably 250 to 900 MPa, still more preferably 300 to 900 MPa, even more preferably 350 to 800 MPa, and even more preferably 400 to 700 MPa. Further, when the thermoplastic polyolefin is a 3-methyl-1-butene-based polymer, the higher the storage modulus E' at 70°C, the more likely the values of the elongation at break in the MD direction and the ratio of the elongation at break [MD / TD] will be larger. As described above, the values of the storage modulus E' at 70°C, the storage modulus E' at 150°C, and the storage modulus E' at 270°C of the TPO-based film can be specifically measured by the method described in the examples below.

[0014] Also, the storage modulus E' at 270°C, the storage modulus E' at 150°C, and the storage modulus E' at 70°C of the TPO-based film can be adjusted by, for example, the following methods. For example, each of the storage moduli E' can also be adjusted by the components contained in the resin composition. For example, when the values of the storage moduli of the thermoplastic polyolefin contained in the resin composition at each of the above temperatures are larger, each of the storage moduli E' is more likely to be larger. On the other hand, when the values of the storage moduli of the thermoplastic polyolefin contained in the resin composition at each of the above temperatures are smaller, each of the storage moduli E' is more likely to be smaller. For example, in one aspect of the present invention, when the resin composition contains an alkyl radical scavenger described later, each of the storage moduli E' is more likely to be larger than when not containing an alkyl radical scavenger. For example, in one aspect of the present invention, when the resin composition contains an antioxidant described later, each of the storage moduli E' is more likely to be larger than when not containing an antioxidant.

[0015] Also, each of the storage moduli E' can be adjusted by the molding conditions of the TPO-based film. For example, in one aspect of the present invention, when the TPO-based film is formed using the method for producing a thermoplastic polyolefin-based film, which is one aspect of the present invention described later, the temperature at which the resin composition in step (I) is melted is adjusted to a lower temperature within the temperature range where the resin composition can be sufficiently melted and film formation is possible, so that each of the storage elastic moduli E' can be more easily increased. For example, in step (I), when the resin composition is melted in an inert atmosphere or in a low oxygen state, each of the storage elastic moduli E' can be more easily increased compared to the case where these conditions are not satisfied. For example, in step (II) of the production method, the temperature of the casting drum that contacts the melt extrudate of the resin composition is adjusted to a higher temperature within the temperature range where film formation is possible, so that each of the storage elastic moduli E' can be more easily increased. For example, in the production method, when, during step (I), a melt of the resin composition containing the thermoplastic polyolefin is extruded through a T-die to form a film, the draft ratio [Tt / Ft], which is the ratio of the gap thickness (Tt) of the lip portion of the T-die to the thickness (Ft) of the resulting thermoplastic polyolefin-based film, is adjusted to a larger value within the range where film formation is possible, so that each of the storage elastic moduli E' can be more easily increased. Details regarding each component of the resin composition and each condition of the production method will be described later.

[0016] Further, the TPO-based film preferably has a yellowness index (YI) of 3.50 or less, more preferably 2.50 or less, still more preferably 1.50 or less, even more preferably 1.00 or less, and even more preferably 0.50 or less. Also, the lower limit value of the yellowness index (YI) is not particularly limited, but for example, it is preferably 0.00. In other words, in one aspect of the TPO-based film, the yellowness index (YI) is preferably from 0.00 to 3.50, more preferably from 0.00 to 2.50, still more preferably from 0.00 to 1.50, even more preferably from 0.00 to 1.00, and even more preferably from 0.00 to 0.50. As described above, the yellowness index (YI) value of the TPO-based film can be specifically measured by the method described in the examples below.

[0017] Also, the curl degree for evaluating the flatness of the TPO-based film is preferably 26 mm or less, more preferably 22 mm or less, still more preferably 18 mm or less, even more preferably 14 mm or less, even more preferably 10 mm or less, even more preferably 6 mm or less, and even more preferably 2 mm or less. Also, the lower limit value of the curl degree is not particularly limited, but for example, it is preferably 0 mm. In other words, in one aspect of the TPO-based film, the curl degree is preferably 0 to 26 mm, more preferably 0 to 22 mm, still more preferably 0 to 18 mm, even more preferably 0 to 14 mm, even more preferably 0 to 10 mm, even more preferably 0 to 6 mm, and even more preferably 0 to 2 mm. As described above, the curl degree value for evaluating the flatness of the TPO-based film can be specifically measured by the method described in the examples below.

[0018] The thickness of the TPO-based film is not particularly limited as long as the effects of the present invention are achieved, and can be appropriately set according to the use of the film. In one aspect of the present invention, the thickness of the TPO-based film is, for example, preferably 1 to 1,000 μm, more preferably 5 to 500 μm, and still more preferably 10 to 100 μm from the viewpoints of film formability and handling properties of post-processing of the film. The thickness of the TPO-based film can be specifically measured by the method described in the examples below.

[0019] <Resin composition containing thermoplastic polyolefin> The TPO-based film is formed from a resin composition containing a thermoplastic polyolefin as a main component. That is, the resin composition contains a thermoplastic polyolefin as a main component.

[0020] (Thermoplastic polyolefin) As the thermoplastic polyolefin, a thermoplastic polyolefin can be used such that the obtained TPO-based film has an elongation at break in the MD direction of 10.0% or more, a ratio [MD / TD] of the elongation at break in the MD direction to the elongation at break in the TD direction of 2.0 to 30.0, and a storage elastic modulus E' at 270°C of 1 MPa or more. As the thermoplastic polyolefin, it is preferably an aliphatic polyolefin, and from the viewpoint of more easily obtaining a TPO-based film having good heat resistance and thermoformability, it is more preferably a 3-methyl-1-butene-based polymer.

[0021] 〔3-Methyl-1-butene-based polymer〕 The 3-methyl-1-butene-based polymer (hereinafter also abbreviated as "P3MB") may be a 3-methyl-1-butene homopolymer or a copolymer of 3-methyl-1-butene and an unsaturated hydrocarbon other than 3-methyl-1-butene. Examples of the unsaturated hydrocarbon include ethylene or an α-olefin other than 3-methyl-1-butene, and from the viewpoint of good copolymerizability, it is preferably an α-olefin having 3 to 20 carbon atoms other than 3-methyl-1-butene. From the viewpoint of preferably exhibiting the physical properties of 3-methyl-1-butene, the 3-methyl-1-butene-based polymer is preferably at least one selected from the group consisting of a 3-methyl-1-butene homopolymer and a copolymer of 3-methyl-1-butene and at least one selected from the group consisting of ethylene and an α-olefin having 3 to 20 carbon atoms other than 3-methyl-1-butene. Hereinafter, in this specification, unless otherwise specified, the description of "α-olefin" refers to an α-olefin other than 3-methyl-1-butene.

[0022] When the P3MB is a copolymer of 3-methyl-1-butene and at least one selected from the group consisting of ethylene and α-olefin, from the viewpoint of more easily obtaining a TPO-based film having easy tearability and good heat resistance and thermoformability, the content ratio of the structural unit derived from at least one selected from the group consisting of ethylene and α-olefin in the copolymer is preferably more than 0 mol% and 20 mol% or less in 100 mol% of the total amount of the structural units derived from monomers. Also, from the viewpoint of preferably exhibiting the physical properties of at least one selected from the group consisting of ethylene and α-olefin, the content ratio of the structural unit derived from at least one selected from the group consisting of ethylene and α-olefin in the copolymer is more preferably 0.1 mol% or more, still more preferably 0.3 mol% or more, and even more preferably 0.5 mol% or more in 100 mol% of the total amount of the structural units derived from monomers. Also, from the viewpoint of more easily obtaining a TPO-based film having easy tearability and good heat resistance and thermoformability while easily maintaining the physical properties of 3-methyl-1-butene, the content ratio of the structural unit derived from at least one selected from the group consisting of ethylene and α-olefin in the copolymer is more preferably 15 mol% or less, still more preferably 10 mol% or less, and even more preferably 5 mol% or less in 100 mol% of the total amount of the structural units derived from monomers. As described above, these stepwise-described lower limit values and upper limit values can be combined independently. For example, from the viewpoint of more easily obtaining a TPO-based film having easy tearability and good heat resistance and thermoformability, in one aspect of the copolymer, the content ratio of the structural unit derived from at least one selected from the group consisting of ethylene and α-olefin in the copolymer is more preferably 0.1 to 15 mol%, still more preferably 0.3 to 10 mol%, and even more preferably 0.5 to 5 mol% in 100 mol% of the total amount of the structural units derived from monomers. Here, in this specification, the "total amount of structural units derived from monomers" means, for example, when polymerizing a polymer, structural units contained due to impurities in the polymerization solvent or monomers, and components necessary for polymerizing the polymer such as catalysts, polymerization initiators, chain transfer agents, coupling agents, etc., but does not include structural units derived from components other than monomers. Here, the content ratio of the structural units derived from at least one selected from the group consisting of ethylene and α-olefins in the copolymer can be determined by a Fourier transform infrared spectrophotometer (FT-IR). Specifically, it can be measured by the method described in the examples below.

[0023] When the P3MB is a copolymer of 3-methyl-1-butene and at least one selected from the group consisting of ethylene and α-olefins, from the viewpoint of making it easier to obtain a TPO-based film having easy tearability and good heat resistance and thermoformability, the content ratio of the structural units derived from 3-methyl-1-butene in the copolymer is preferably 80 mol% or more and less than 100 mol% in 100 mol% of the total amount of the structural units derived from monomers. Also, from the viewpoint of easily maintaining the physical properties of 3-methyl-1-butene and making it easier to obtain a TPO-based film having easy tearability and good heat resistance and thermoformability, the content ratio of the structural units derived from 3-methyl-1-butene in the copolymer is more preferably 85 mol% or more, still more preferably 90 mol% or more, and even more preferably 95 mol% or more in 100 mol% of the total amount of the structural units derived from monomers. Also, from the viewpoint of preferably exhibiting the physical properties of at least one selected from the group consisting of ethylene and α-olefins, the content ratio of the structural units derived from 3-methyl-1-butene in the copolymer is more preferably 99.9 mol% or less, still more preferably 99.7 mol% or less, and even more preferably 99.5 mol% or less in 100 mol% of the total amount of the structural units derived from monomers. As described above, the lower limit values and upper limit values described stepwise can be combined independently of each other. For example, from the viewpoint of making it easier to obtain a TPO-based film having easy tearability and good heat resistance and thermoformability, in one aspect of the copolymer, the content ratio of the structural unit derived from 3-methyl-1-butene in the copolymer is more preferably 85 to 99.9 mol%, still more preferably 90 to 99.7 mol%, even more preferably 95 to 99.5 mol% in 100 mol% of the total amount of the structural units derived from the monomers.

[0024] From the viewpoint of preferably exerting the physical properties of 3-methyl-1-butene, the α-olefin having 3 to 20 carbon atoms is preferably an α-olefin having 4 to 16 carbon atoms, more preferably an α-olefin having 4 to 12 carbon atoms, still more preferably an α-olefin having 4 to 10 carbon atoms. Further, the α-olefin having 3 to 20 carbon atoms may be linear or branched. Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and the like. The α-olefin having 3 to 20 carbon atoms may be used alone or in combination of two or more.

[0025] Further, from the viewpoint of the balance between the processability of the resin composition and the heat resistance and thermoformability of the obtained TPO-based film, the melting point of the P3MB is preferably 260 to 310°C, more preferably 265 to 305°C, still more preferably 270 to 300°C, even more preferably 275 to 295°C, even more preferably 280 to 290°C. Specifically, the melting point can be measured by the method described in the examples described later.

[0026] Further, from the viewpoint of the balance between the fluidity during molding of the resin composition and the mechanical strength of the resulting TPO-based film, the melt viscosity of the P3MB is preferably 10 to 9,500 Pa·s, more preferably 50 to 5,000 Pa·s, still more preferably 100 to 2,000 Pa·s, and even more preferably 200 to 1,000 Pa·s. Specifically, the melt viscosity can be measured by the method described in the examples below.

[0027] Further, the method for producing the P3MB is not particularly limited, and for example, it can be produced using well-known catalysts such as Ziegler-Natta catalysts and metallocene catalysts. Further, the P3MB can be obtained as a powder, for example, by homopolymerizing 3-methyl-1-butene or copolymerizing 3-methyl-1-butene and the above α-olefin in the presence of a catalyst as described in JP-A-61-103910. Further, the stereoregularity of the P3MB may be isotactic or syndiotactic. Further, the copolymer may be a random copolymer, a block copolymer, or an alternating copolymer.

[0028] Further, from the viewpoint of more easily obtaining a TPO-based film having easy tearability and good heat resistance and thermoformability, the content of the thermoplastic polyolefin in the resin composition is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, still more preferably 65.0% by mass or more, even more preferably 75.0% by mass or more, even more preferably 85.0% by mass or more, even more preferably 90.0% by mass or more, even more preferably 95.0% by mass or more, and even more preferably 96.0% by mass or more in 100% by mass of the total amount of the resin composition. Further, the content of the thermoplastic polyolefin in the resin composition is 100% by mass or less, preferably 99.9% by mass or less, more preferably 99.8% by mass or less, and still more preferably 99.7% by mass or less in 100% by mass of the total amount of the resin composition. As described above, the lower limit values and upper limit values described step by step can be combined independently of each other. For example, from the viewpoint of more easily obtaining a TPO-based film having easy tearability and good heat resistance and thermoformability, in one aspect of the present invention, the content of the thermoplastic polyolefin in the resin composition is preferably 50.0 to 100% by mass, more preferably 50.0 to 99.9% by mass, still more preferably 60.0 to 99.9% by mass, even more preferably 65.0 to 99.9% by mass, even more preferably 75.0 to 99.9% by mass, even more preferably 85.0 to 99.9% by mass, even more preferably 90.0 to 99.9% by mass, even more preferably 95.0 to 99.9% by mass, even more preferably 95.0 to 99.8% by mass, even more preferably 95.0 to 99.7% by mass, even more preferably 96.0 to 99.7% by mass in 100% by mass of the total amount of the resin composition.

[0029] Also, in one aspect of the TPO-based film, the content of P3MB in the resin composition is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, still more preferably 65.0% by mass or more, even more preferably 75.0% by mass or more, even more preferably 85.0% by mass or more, even more preferably 90.0% by mass or more, even more preferably 95.0% by mass or more, even more preferably 96.0% by mass or more in 100% by mass of the total amount of the resin composition from the viewpoint of more easily obtaining a TPO-based film having easy tearability and good heat resistance and thermoformability. Also, the content of P3MB in the resin composition is 100% by mass or less, preferably 99.9% by mass or less, more preferably 99.8% by mass or less, still more preferably 99.7% by mass or less in 100% by mass of the total amount of the resin composition. As described above, the lower limit values and upper limit values described step by step can be combined independently of each other. For example, from the viewpoint of making it easier to obtain a TPO-based film having easy tearability and good heat resistance and thermoformability, in one aspect of the present invention, the content of P3MB in the resin composition is preferably 50.0 to 100% by mass, more preferably 50.0 to 99.9% by mass, still more preferably 60.0 to 99.9% by mass, even more preferably 65.0 to 99.9% by mass, even more preferably 75.0 to 99.9% by mass, even more preferably 85.0 to 99.9% by mass, even more preferably 90.0 to 99.9% by mass, even more preferably 95.0 to 99.9% by mass, even more preferably 95.0 to 99.8% by mass, even more preferably 95.0 to 99.7% by mass, even more preferably 96.0 to 99.7% by mass in 100% by mass of the total amount of the resin composition.

[0030] Also, from the viewpoint of making it easier to obtain a TPO-based film having easy tearability and good heat resistance and thermoformability, the content of P3MB in the resin composition is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, still more preferably 65.0% by mass or more, even more preferably 75.0% by mass or more, even more preferably 85.0% by mass or more, even more preferably 90.0% by mass or more, even more preferably 95.0% by mass or more, even more preferably 96.0% by mass or more in 100% by mass of the total amount of the polymer in the resin composition. Also, the content of P3MB in the resin composition is 100% by mass or less in 100% by mass of the total amount of the polymer in the resin composition. In other words, in one aspect of the present invention, the content of P3MB in the resin composition is preferably 50.0 to 100% by mass, more preferably 60.0 to 100% by mass, still more preferably 65.0 to 100% by mass, even more preferably 75.0 to 100% by mass, even more preferably 85.0 to 100% by mass, even more preferably 90.0 to 100% by mass, even more preferably 95.0 to 100% by mass, even more preferably 95.0 to 100% by mass, even more preferably 95.0 to 100% by mass, even more preferably 96.0 to 100% by mass in 100% by mass of the total amount of the polymer in the resin composition. Also, the content of P3MB in the resin composition may be 100% by mass based on 100% by mass of the total amount of the polymers in the resin composition.

[0031] (Alkyl radical scavenger) The resin composition preferably contains an alkyl radical scavenger. By including an alkyl radical scavenger in the resin composition, it becomes easier to obtain a TPO-based film having easy tearability, good heat resistance, and good thermoformability. Also, from the viewpoint of further improving the flatness and yellowness index (YI) of the TPO-based film, it is preferable. In this specification, the "alkyl radical scavenger" means a compound that reacts with an alkyl radical derived from the P3MB and stabilizes the alkyl radical. By stabilizing the alkyl radical, a function of suppressing a chain carbon-carbon bond dissociation reaction starting from the alkyl radical is exhibited. The resin composition preferably contains at least one selected from the group consisting of an acrylic phenol compound and a benzofuranone compound as the alkyl radical scavenger. The alkyl radical scavenger may be used alone or in combination of two or more.

[0032] 〔Acrylic phenol compound〕 As the acrylic phenol compound, for example, a compound represented by the following general formula (I) can be used.

[0033]

Chemical formula

[0034] In general formula (I), R 1 represents a hydrogen atom or a methyl group, R 2 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R 3 , R 4 , R 5 and R 6 each independently represent an alkyl group having 1 to 9 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. The alkyl group having 1 to 9 carbon atoms may be linear or branched. Examples of the alkyl group having 1 to 9 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and an n-nonyl group. R 1 is preferably a hydrogen atom. R 2 is preferably a hydrogen atom or a methyl group, more preferably a methyl group. R 3 , R 4 , R 5 and R 6 are each independently preferably an alkyl group having 3 to 8 carbon atoms, more preferably an alkyl group having 5 carbon atoms, and still more preferably a 1,1-dimethylpropyl group.

[0035] Examples of the acrylic phenol compound represented by the general formula (I) include 2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, 2,4-di-t-butyl-6-[1-(3,5-di-t-butyl-2-hydroxyphenyl)ethyl]phenyl acrylate, and 2-t-butyl-6-[(3-t-butyl-2-hydroxy-5-methylphenyl)methyl]-4-methylphenyl acrylate. As the alkyl radical scavenger, a commercially available product may be used. Examples of the acrylic phenol compound represented by the general formula (I) include "Sumilizer (registered trademark) GS" and "Sumilizer (registered trademark) GM" manufactured by Sumitomo Chemical Company, Limited.

[0036] [Benzofuranone compound] As the benzofuranone compound, for example, a compound represented by the following general formula (II) can be used.

[0037]

Chemical formula

[0038] In the general formula (II), R 7 and R 8 each independently represent an alkyl group having 1 to 4 carbon atoms, and R 9 and R 10 each independently represent an alkyl group having 1 to 9 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, and a t-butyl group. The alkyl group having 1 to 9 carbon atoms may be linear or branched. Examples of the alkyl group having 1 to 9 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and an n-nonyl group. R 7 and R 8 are each independently preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group. R 9 and R 10 are each independently preferably an alkyl group having 1 to 4 carbon atoms, more preferably a t-butyl group.

[0039] The benzofuranone compounds represented by the general formula (II) include, for example, 5,7-di-t-butyl-3-(3,4-dimethyl-phenyl)-3H-benzofuran-2-one, 5,7-di(t-butyl)-3-(3,4-dipropyl-phenyl)-3H-benzofuran-2-one, and 4-t-butyl-2-(5-t-butyl-2-oxo-3H-benzofuran-3-yl)phenyl-3,5-di-t-butyl-4-hydroxybenzoate, etc. Commercially available products may be used as the alkyl radical scavenger. Examples of the benzofuranone compound represented by the general formula (II) include the product named "Irganox (registered trademark) HP-136" manufactured by BASF, and the product named "Revonox501" manufactured by Chitec.

[0040] From the viewpoint of making the effects of the present invention more easily exhibited, the content of the alkyl radical scavenger in the resin composition is preferably 0.01 to 1.00 parts by mass, more preferably 0.02 to 0.80 parts by mass, and still more preferably 0.05 to 0.70 parts by mass with respect to 100 parts by mass of the thermoplastic polyolefin. When the resin composition contains two or more kinds of alkyl radical scavengers, the content of the alkyl radical scavenger means the total content of the alkyl radical scavengers.

[0041] (Antioxidant) The resin composition preferably contains an antioxidant. By including an antioxidant in the resin composition, it becomes easier to obtain a TPO-based film having easy tearability, good heat resistance and thermoformability, and from the viewpoint of further improving the flatness and yellowness index (YI) of the TPO-based film, it is also preferable. The resin composition preferably contains at least one selected from the group consisting of phenolic antioxidants and phosphorus-based antioxidants as the antioxidant. The antioxidant may be used alone or in combination of two or more. In this specification, an antioxidant that also acts as the alkyl radical scavenger is regarded as the alkyl radical scavenger.

[0042] [Phenolic antioxidant] Examples of the phenolic antioxidant include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris[(4-t-butyl-3-hydroxy-2,6-xylyl)methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, thiodiethylene-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N’-hexane-1,6-diylbis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionamide], 3,3’,3’’,5,5’,5’’-hexa-t-butyl-α,α’,α’’-(mesitylene-2,4,6-triyl)tri-p-cresol, ethylenebis(oxyethylene)bis[3-(5-t-butyl-4-hydroxy-m-tolyl)propionate], hexamethylene-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,6-di-t-butyl-4-[4,6-bis(octylthio)-1,3,5-triazin-2-ylamino]phenol, 3,9-bis[2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro(5,5)undecane, 4,4’,4’’-(1-methylpropan-3-ylidene)tris(6-t-butyl-m-cresol), 6,6’-di-t-butyl-4,4’-butylidenebis-m-cresol, octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate, and benzenepropanoic acid 3,5-bis-(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl ester, etc.

[0043] Phenolic antioxidants may be commercially available products. For example, "ADEKA STAB (registered trademark) AO series" manufactured by ADEKA Corporation, "Irganox (registered trademark) series" manufactured by BASF Japan Limited, etc. can be mentioned.

[0044] [Phosphorus-based antioxidant] Examples of the phosphorus-based antioxidant include 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, tetrakis(2,4-di-t-butyl-phenyl)-4,4'-biphenylene phosphonite, 2,2-methylenebis(4,6-di-t-butylphenyl) octyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl) ethyl ester phosphite, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol-diphosphite, di-t-butyl-m-cresyl-phosphonite, diethyl [(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)methyl] phosphonate, tris(2,4-di-t-butylphenyl) phosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphonite, 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, tris(2,4-di-t-butylphenyl) phosphite, tris(nonylphenyl) phosphite, tetra-C12-15-alkyl (propane-2,2-diylbis(4,1-phenylene)) bis(phosphite), 2-ethylhexyl diphenyl phosphite, isodecyl diphenyl phosphite, trisisodecyl phosphite, triphenyl phosphite, and 3,9-bis[2,4-bis(1-methyl-1-phenylethyl)phenoxy]-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, etc.

[0045] Phosphorus-based antioxidants may be commercially available products. For example, "ADEKA STAB (registered trademark) PEP series" and "ADEKA STAB (registered trademark) HP series" manufactured by ADEKA Corporation, "Irgafos (registered trademark) series" manufactured by BASF Japan Ltd., and "HOSTANOX (registered trademark) P-EPQ" with the product name manufactured by Clariant Corporation, etc. can be mentioned.

[0046] 〔Other antioxidants〕 As long as the effects of the present invention are achieved, the resin composition may contain other antioxidants other than phenolic antioxidants and phosphorus-based antioxidants as antioxidants. Examples of other antioxidants other than phenolic antioxidants and phosphorus-based antioxidants include sulfur-based antioxidants and amine-based antioxidants, etc.

[0047] From the viewpoint of making it easier to achieve the effects of the present invention, the content of the antioxidant in the resin composition is preferably 0.01 part by mass or more, more preferably 0.10 part by mass or more, based on 100 parts by mass of the thermoplastic polyolefin. Also, from the viewpoints of suppressing the bleed-out and sublimation of the antioxidant from the film, and the viewpoint of economy, etc., the content of the antioxidant in the resin composition is preferably 1.00 part by mass or less, more preferably 0.80 part by mass or less, based on 100 parts by mass of the thermoplastic polyolefin. As described above, the lower limit values and upper limit values described stepwise can be combined independently. For example, as one aspect of the TPO-based film, the content of the antioxidant in the resin composition is preferably 0.01 to 1.00 part by mass, more preferably 0.10 to 0.80 part by mass, based on 100 parts by mass of the thermoplastic polyolefin. In addition, when the resin composition contains two or more kinds of antioxidants, the content of the antioxidant means the total content of the antioxidants.

[0048] (Other additives) The resin composition may contain an alkyl radical scavenger and other additives other than the antioxidant as long as the effects of the present invention are not impaired. Other additives include, for example, antacids, fillers, light stabilizers, antistatic agents, flame retardants, pigments, polymerization inhibitors, heavy metal inactivators, ultraviolet absorbers, nucleating agents, clarifying agents, lubricants, fluorescent brighteners, rust preventives, and sliding agents. These other additives may be used individually or in combination of two or more.

[0049] 〔Antacid〕 From the viewpoint of suppressing deterioration caused by acid components generated from residual metal components and the like during melt-kneading, the resin composition preferably contains an antacid. Examples of the antacid include barium laurate, calcium stearate, zinc stearate, magnesium stearate, aluminum stearate, zinc oleate, magnesium 12-hydroxystearate, and the like. The antacid may be used individually or in combination of two or more. When the resin composition contains an antacid, the content of the antacid in the resin composition can be appropriately determined. For example, it may be 0.01 to 200 parts by mass, 0.01 to 100 parts by mass, 0.01 to 50 parts by mass, 0.01 to 10 parts by mass, 0.01 to 1.00 parts by mass, or 0.1 to 0.80 parts by mass with respect to 100 parts by mass of the thermoplastic polyolefin.

[0050] 〔Filler〕 Examples of the filler include fibrous compounds such as glass fiber, alumina fiber, resin fiber, carbon fiber, and cellulose fiber; plate-like compounds such as mica, talc, montmorillonite, and plate-like aluminum; spherical compounds such as glass beads, shirasu balloons, and acrylic balloons; needle-like compounds such as needle-like metal titanates, wollastonite, needle-like silica, and tin oxide; powdery compounds such as powdery metal titanates, micronized wood chips, titanium oxide, calcium carbonate, silica, and alumina. These fillers may be surface-treated with, for example, a silane coupling agent. Further, a compatibilizer may be used to enhance the dispersibility of the filler. The filler may be used alone or in combination of two or more kinds. When the resin composition contains a filler, the content of the filler in the resin composition can be appropriately determined. For example, it may be 0.01 to 300 parts by mass, or 0.1 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic polyolefin.

[0051] In one aspect of the present invention, from the viewpoint of more easily obtaining a TPO-based film having easy tearability and good heat resistance and thermoformability, the total content of the thermoplastic polyolefin, the alkyl radical scavenger and the antioxidant in the resin composition is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, still more preferably 70.0% by mass or more, even more preferably 80.0% by mass or more, even more preferably 90.0% by mass or more, even more preferably 95.0% by mass or more in 100% by mass of the total amount of the resin composition. Also, the total content of the thermoplastic polyolefin, the alkyl radical scavenger and the antioxidant in the resin composition is 100% by mass or less, preferably 99.9% by mass or less in 100% by mass of the total amount of the resin composition. As described above, these stepwise-described lower and upper limit values can be combined independently. For example, from the viewpoint of more easily obtaining a TPO-based film having easy tearability and good heat resistance and thermoformability, in one aspect of the present invention, the total content of the thermoplastic polyolefin, the alkyl radical scavenger and the antioxidant is preferably 50.0 to 100% by mass, more preferably 50.0 to 99.9% by mass, still more preferably 60.0 to 99.9% by mass, even more preferably 70.0 to 99.9% by mass, even more preferably 80.0 to 99.9% by mass, even more preferably 90.0 to 99.9% by mass, even more preferably 95.0 to 99.9% by mass in 100% by mass of the total amount of the resin composition.

[0052] In one aspect of the present invention, in the resin composition, the total content of the thermoplastic polyolefin, the alkyl radical scavenger, the antioxidant, and the other additives is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, still more preferably 70.0% by mass or more, even more preferably 80.0% by mass or more, even more preferably 90.0% by mass or more, and even more preferably 95.0% by mass or more in 100% by mass of the total amount of the resin composition, from the viewpoint of more easily obtaining a TPO-based film having easy tearability, good heat resistance, and thermoformability. Also, in the resin composition, the total content of the thermoplastic polyolefin, the alkyl radical scavenger, the antioxidant, and the other additives is 100% by mass or less in 100% by mass of the total amount of the resin composition. In other words, in one aspect of the present invention, in the resin composition, the total content of the thermoplastic polyolefin, the alkyl radical scavenger, the antioxidant, and the other additives is preferably 50.0 to 100% by mass, more preferably 60.0 to 100% by mass, still more preferably 70.0 to 100% by mass, even more preferably 80.0 to 100% by mass, even more preferably 90.0 to 100% by mass, and even more preferably 95.0 to 100% by mass in 100% by mass of the total amount of the resin composition. Further, in one aspect of the present invention, in the resin composition, the total content of the thermoplastic polyolefin, the alkyl radical scavenger, the antioxidant, and the other additives may be 100% by mass in 100% by mass of the total amount of the resin composition.

[0053] Also, in one aspect of the present invention, it is preferable that the resin composition substantially does not contain a thermosetting resin. Here, "substantially does not contain" specifically means that in 100% by mass of the resin composition, the content of the thermosetting resin is 5.0% by mass or less, preferably 1.0% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less. Further, the resin composition may have a content of the thermosetting resin of 0% by mass in 100% by mass of the resin composition. In other words, in one aspect of the present invention, the content of the thermosetting resin in the resin composition is 0 to 5.0% by mass in 100% by mass of the resin composition, preferably 0 to 1.0% by mass, more preferably 0 to 0.1% by mass, still more preferably 0 to 0.05% by mass, even more preferably 0 to 0.01% by mass, and may be 0% by mass. That is, it is preferable that the TPO-based film substantially does not contain a thermosetting resin.

[0054] Also, in one aspect of the present invention, it is preferable that the resin composition substantially does not contain a cyclic polyolefin as the thermoplastic polyolefin. Here, "substantially does not contain" specifically means that in 100% by mass of the resin composition, the content of the cyclic polyolefin is 5.0% by mass or less, preferably 1.0% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less. Further, the resin composition may have a content of the cyclic polyolefin of 0% by mass in 100% by mass of the resin composition. In other words, in one aspect of the present invention, the content of the cyclic polyolefin in the resin composition is 0 to 5.0% by mass in 100% by mass of the resin composition, preferably 0 to 1.0% by mass, more preferably 0 to 0.1% by mass, still more preferably 0 to 0.05% by mass, even more preferably 0 to 0.01% by mass, and may be 0% by mass. That is, it is preferable that the TPO-based film substantially does not contain a cyclic polyolefin. The "cyclic polyolefin" refers to a polymer having an alicyclic structure (cycloolefin skeleton) in the main chain, and refers to a polymer containing at least 10 mol% or more of a structural unit derived from a monomer capable of introducing the alicyclic structure into the main chain of the polymer, based on 100 mol% of the total amount of the structural units constituting the polymer. The monomer capable of introducing the alicyclic structure into the main chain of the polymer is not particularly limited, and examples thereof include substituted or unsubstituted norbornene, substituted or unsubstituted tetracyclododecene, substituted or unsubstituted dicyclopentadiene, and the like. As an example of the cyclic polyolefin, for example, a cyclic olefin monomer such as substituted or unsubstituted norbornene is subjected to ring-opening metathesis polymerization (ROMP) to obtain a ring-opened polymer, and then a polymer obtained by hydrogenating double bonds in the polymer, and the like can be mentioned. Further, for example, a copolymer obtained by addition polymerization of the cyclic olefin monomer and an olefin such as ethylene can be mentioned. Examples of commercially available products of the cyclic polyolefin include, for example, "ZEONEX (registered trademark)", "ZEONOR (registered trademark)" manufactured by Nippon Zeon Co., Ltd.; "APEL (registered trademark)" manufactured by Mitsui Chemicals, Inc.; "ARTON (registered trademark)" manufactured by JSR Corporation; "TOPAS (registered trademark)" of Topas Advanced Polymers GmbH, and the like.

[0055] (Method for producing resin composition) The resin composition can be produced by blending and kneading other components such as the above-mentioned various additives in addition to the thermoplastic polyolefin. The blending method of each component is not particularly limited as long as the effects of the present invention are achieved, and for example, a method of melt-kneading using a twin-screw kneading extruder can be used. In addition, for example, when only a 3-methyl-1-butene-based polymer is used as the thermoplastic polyolefin and other polymers and other components such as the above-mentioned various additives are not blended, since the resin composition is composed of a 3-methyl-1-butene-based polymer, it is not necessary to go through a step of obtaining the resin composition by melt-kneading or the like. The conditions for obtaining the resin composition by melt-kneading will be described below.

[0056] 〔Melting and kneading conditions〕 The melting and kneading conditions for obtaining the resin composition by melting and kneading are not particularly limited as long as the effects of the present invention are achieved. However, it is preferable to inject an inert gas into the interior of the melting and kneading machine for melting and kneading, or to perform melting and kneading by depressurizing and degassing the interior of the melting and kneading machine. By melting and kneading in an inert atmosphere or a low-oxygen state, it is possible to suppress the deterioration of the physical properties of the resin composition due to oxygen, making it easier to obtain a TPO-based film having easy tearability, good heat resistance, and good thermoformability. Also, from the viewpoint of further improving the flatness and yellowness index (YI) of the TPO-based film, it is preferable. Here, the "low-oxygen state" refers to a state in which the oxygen concentration inside the melting and kneading machine is lower than before depressurizing and degassing by performing depressurizing and degassing inside the melting and kneading machine. Also, in the state of "in an inert atmosphere", the oxygen concentration inside the melting and kneading machine is lower than before injecting the inert gas because an inert gas is injected into the interior of the melting and kneading machine. Therefore, the concept of "low-oxygen state" may include the state of "in an inert atmosphere". In the "low-oxygen state", the oxygen concentration inside the melting and kneading machine is preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less. Also, the measurement of the oxygen concentration can be performed using an oxygen concentration meter such as a diaphragm-type galvanic type. As the oxygen concentration meter, for example, "XP-3180E" (diaphragm-type galvanic cell type) manufactured by Shin Cosmos Electric Co., Ltd. and its successor model "XP-3380II-E" (galvanic cell type) can be used.

[0057] A method of injecting an inert gas into a melt kneader and performing melt kneading may be, for example, performing melt kneading by charging each component while injecting an inert gas into the melt kneader; after charging each component into the melt kneader, preferably before starting temperature increase or before starting shearing, more preferably before starting temperature increase and before starting shearing, melt kneading may be performed by injecting an inert gas; or, after injecting an inert gas into the melt kneader, melt kneading may be performed by charging each component from a sealed supply unit. Also, during melt kneading, the inert gas may continue to be injected into the melt kneader. The method of injecting the inert gas can be carried out according to the equipment provided in each melt kneader, and it is preferable that the inert gas can be injected throughout the whole from the supply unit of the inert gas to the heating unit where melt kneading is performed, and there is no particular limitation on the injection method. For example, it may be carried out from the supply unit of a gas such as an inert gas provided in the melt kneader, it may be carried out from the supply unit of each component provided in the melt kneader, or it may be carried out from the gas vent provided in the melt kneader. Examples of the inert gas include nitrogen gas, helium gas, neon gas, argon gas, krypton gas, and carbon dioxide gas, etc. From the viewpoint of high availability and versatility, nitrogen gas is preferable.

[0058] A method of performing melt kneading by depressurizing and degassing the inside of a melt kneader may be, for example, performing melt kneading by charging each component while depressurizing and degassing the inside of the melt kneader, or after charging each component into the melt kneader, preferably before starting temperature increase or before starting shearing, more preferably before starting temperature increase and before starting shearing, melt kneading may be performed by depressurizing and degassing the inside of the melt kneader, or after depressurizing and degassing the inside of the melt kneader, melt kneading may be performed by charging each component from a sealed supply unit. Also, during melt kneading, the depressurizing and degassing inside the melt kneader may be carried out intermittently or continuously. The method of depressurizing and degassing the inside of the melt kneader can be carried out according to the equipment provided in each melt kneader, and for example, it may be carried out from a vacuum vent. For depressurizing and degassing, for example, a vacuum pump can be used. The vacuum degassing inside the melt kneader is not limited to the degassing method as long as melt kneading can be performed in an inert atmosphere or a low oxygen state. When performing vacuum degassing, the inside of the melt kneader can be set to a vacuum state of, for example, 0.1 to 50 kPa.

[0059] The melt kneader includes equipment that can inject an inert gas into the inside of the melt kneader for melt kneading, or equipment that can perform vacuum degassing inside the melt kneader for melt kneading. A single-screw extruder, a multi-screw extruder, a kneader, a Banbury mixer, etc. can be used.

[0060] The above-mentioned injection of inert gas and vacuum degassing may be used in combination. In this case, it is preferable to inject the inert gas upstream of the melt kneader before or together with the raw material, and on the other hand, perform vacuum degassing downstream of it. Further, it is more preferable to inject the inert gas upstream of the melt kneader before or together with the raw material, perform vacuum degassing downstream of it, and continue both the injection of inert gas and vacuum degassing during melt kneading.

[0061] The temperature during melt kneading is preferably 280 to 323 °C. When the temperature during melt kneading is 280 °C or higher, for example, even when using a 3-methyl-1-butene-based polymer suitable as the thermoplastic polyolefin, the 3-methyl-1-butene-based polymer can be sufficiently melted, and it becomes easier to disperse the above-mentioned various additives. When the temperature during melt kneading is 323 °C or lower, decomposition of the thermoplastic polyolefin or the above-mentioned various additives due to heat can be suppressed. From the viewpoint of sufficiently dispersing the above-mentioned various additives in the thermoplastic polyolefin, the temperature during melt kneading is more preferably 285 °C or higher, further preferably 290 °C or higher, and even more preferably 292 °C or higher. In addition, from the perspective of being able to suppress the decomposition of each component and making it easier to obtain a TPO-based film having better tearability, heat resistance, and thermoformability, and from the perspective of further improving the flatness and yellowness index (YI) of the TPO-based film, the temperature during the melt kneading is more preferably 315 °C or lower, still more preferably 305 °C or lower, even more preferably 300 °C or lower, and even more preferably 298 °C or lower. As described above, these stepwise-described lower and upper limit values can be combined independently. For example, from the perspective of sufficiently melt-kneading each component, from the perspective of making it easier to obtain a TPO-based film having better tearability, heat resistance, and thermoformability, and from the perspective of further improving the flatness and yellowness index (YI) of the TPO-based film, in one aspect of the present invention, the temperature during the melt kneading is preferably 280 to 323 °C, more preferably 285 to 315 °C, still more preferably 290 to 305 °C, even more preferably 290 to 300 °C, and even more preferably 292 to 298 °C.

[0062] The TPO-based film can be produced, for example, by an extrusion molding method such as a T-die casting method or an inflation method, and is preferably produced by a T-die casting method. Further, from the perspective of making it easier to obtain the TPO-based film, it is more preferable to produce it using the method for producing a thermoplastic polyolefin-based film, which is one aspect of the present invention described later.

[0063] [Method for producing a thermoplastic polyolefin-based film] The method for producing a thermoplastic polyolefin-based film, which is one aspect of the present invention, includes a step (I) of melt-extruding a resin composition containing a thermoplastic polyolefin as a main component, and has an elongation at break in the MD direction of 10.0% or more, a ratio [MD / TD] of the elongation at break in the MD direction to the elongation at break in the TD direction of 2.0 to 30.0, and a storage elastic modulus E' at 270 °C of 1 MPa or more. It is a method for producing a thermoplastic polyolefin-based film. The thermoplastic polyolefin-based film obtained by the manufacturing method is the same as that described in the column of the "thermoplastic polyolefin-based film" above, and its preferred embodiments are also the same. Therefore, the resin composition containing the thermoplastic polyolefin as a main component used in the manufacturing method, as well as the thermoplastic polyolefin contained in the resin composition and other respective components that the resin composition may contain, are also the same as those described above, and their preferred embodiments are also the same. Therefore, the thermoplastic polyolefin-based film, which is one embodiment of the present invention described above, is preferably a thermoplastic polyolefin-based film manufactured by the manufacturing method.

[0064] <Step (I)> Step (I) is a step of melt-extruding a resin composition containing a thermoplastic polyolefin as a main component. As a method for melt-extruding the resin composition, from the viewpoint of easily obtaining a film excellent in manufacturing ease and dimensional accuracy, it is preferable to use an extruder. As the extruder, for example, a single-screw extruder or a multi-screw extruder such as a twin-screw kneading extruder can be used. When the resin composition is at least one of a composition containing a plurality of polymers and a composition containing the various additives described above, from the viewpoint of sufficiently melt-kneading each component, it is preferable to use a multi-screw extruder such as a twin-screw kneading extruder.

[0065] During Step (I), it is preferable to melt the resin composition in an inert atmosphere or a low-oxygen state, and it is more preferable to melt it in an inert atmosphere. By melting the resin composition in an inert atmosphere or a low-oxygen state, it is possible to suppress the deterioration of the physical properties of the resin composition due to oxygen, making it easier to obtain a TPO-based film having better tearability, heat resistance, and thermoformability. Also, from the viewpoint of further improving the flatness and yellowness index (YI) of the TPO-based film, it is preferable. Further, from the viewpoint of more easily obtaining higher values for the elongation at break in the MD direction and the ratio of the elongation at break [MD / TD], it is also preferable. For example, when using an extruder in step (I), it is preferable to melt the resin composition by using at least one method selected from injecting an inert gas into the interior of the extruder to melt the resin composition and evacuating the interior of the melt kneader to melt the resin composition.

[0066] As a method of injecting an inert gas into the interior of the extruder to melt the resin composition, for example, while injecting an inert gas into the interior of the extruder, the resin composition prepared in advance by the method described above in the column of "Method for Producing Resin Composition" is charged from a raw material inlet such as a hopper, and the resin composition is melted in the extruder; or, after charging the resin composition into the interior of the extruder from a raw material inlet such as a hopper, preferably before starting the temperature rise or before starting the shear, more preferably before starting the temperature rise and before starting the shear, an inert gas is injected and then the resin composition is melted in the extruder; and the like. Also, while the resin composition is being melted, an inert gas may be continuously injected into the interior of the extruder, and it is preferable to continuously inject an inert gas into the interior of the extruder while the resin composition is being melted. The method of injecting the inert gas can be carried out according to the equipment provided in the extruder used, and it is preferable that the inert gas can be injected into the entire area from the supply part of the inert gas of the extruder to the heating part where melt kneading is carried out for melt kneading, and there is no particular limitation on the injection method. For example, it may be carried out from the supply part of a gas such as an inert gas provided in the extruder, or it may be carried out from the supply part of each component such as a hopper provided in the extruder. Examples of the inert gas include nitrogen gas, helium gas, neon gas, argon gas, krypton gas, and carbon dioxide gas, etc. From the viewpoint of high availability and versatility, nitrogen gas is preferable.

[0067] As a method of melting the resin composition by performing vacuum degassing inside the extruder, for example, while performing vacuum degassing inside the extruder, the resin composition prepared in advance by the method described above in the column of "Method for Producing Resin Composition" and the like is charged from a raw material inlet such as a hopper and melted; or, after charging the resin composition into the extruder from a raw material inlet such as a hopper, preferably before starting the temperature increase or before starting the shear, more preferably before starting the temperature increase and before starting the shear, the inside of the extruder is vacuum degassed and melted; and the like. Also, while the resin composition is being melted, the vacuum degassing inside the extruder may be performed intermittently or continuously, and it is preferable to perform the vacuum degassing continuously while the resin composition is being melted. There is no limitation on the vacuum degassing method as long as the resin composition can be melt-kneaded in an inert atmosphere or a low-oxygen state inside the extruder. For example, in one aspect of the manufacturing method, the vacuum degassing inside the extruder can be performed according to the equipment provided in the extruder used. For example, it may be performed from a vacuum vent. For vacuum degassing, a vacuum pump such as a vacuum pump can be used. Also, by performing vacuum degassing inside the extruder, it is possible to remove the moisture remaining in the resin composition and organic solvents that vaporize at the melting temperature. Therefore, when extruding the melt from a T-die or the like, it is possible to suppress foaming of the melt caused by moisture and the like, which is preferable. From such a viewpoint, the vacuum degassing is preferably performed after the resin composition is melted and before it is extruded. For example, it may be performed from a vent provided in the barrel corresponding to the shear section position of the extruder.

[0068] The above-described injection of an inert gas and vacuum degassing may be used in combination. In this case, it is preferable to inject the inert gas upstream of the extruder before charging the raw material or together with the raw material, and on the other hand, perform vacuum degassing downstream of that. Further, it is more preferable to inject the inert gas upstream of the extruder before charging the raw material or together with the raw material, and on the other hand, perform vacuum degassing downstream of that and continue both the injection of the inert gas and the vacuum degassing during the melt-kneading.

[0069] Further, as described above, the resin composition used in the step (I) may be the resin composition prepared in advance by the method described in the column of "Method for Producing Resin Composition" or the like, or, during the step (I), for example, a twin-screw kneading extruder is used as the extruder, and in the extruder, each of the above-described components is kneaded to prepare the resin composition, and a method of directly extrusion-molding the molten resin composition from the extruder may be used.

[0070] During the step (I), it is preferable to melt the resin composition containing the thermoplastic polyolefin as the main component at 280 to 323°C. During the step (I), when the temperature at which the resin composition is melted is 280°C or higher, for example, even when a 3-methyl-1-butene-based polymer suitable as the thermoplastic polyolefin is used, the resin composition can be sufficiently melted, and it is preferable because the TPO-based film is easily formed. From such a viewpoint, during the step (I), the temperature at which the resin composition is melted is more preferably 285°C or higher, still more preferably 290°C or higher, even more preferably 292°C or higher. Further, when the temperature at which the resin composition is melted is 323°C or lower, decomposition of the thermoplastic polyolefin or each of the above-described additives due to heat can be suppressed. Also, it is preferable from the viewpoint that the storage elastic modulus E' at each of the above-described temperatures is easily improved. Also, from the viewpoints of more easily obtaining a TPO-based film having better tearability, heat resistance, and thermoformability, and that the planarity and yellowness index (YI) of the TPO-based film are further improved. Also, it is preferable from the viewpoint that higher values of the elongation at break in the MD direction and the ratio of the elongation at break [MD / TD] are more easily obtained. From these viewpoints, during the step (I), the temperature at which the resin composition is melted is more preferably 315°C or lower, still more preferably 305°C or lower, even more preferably 300°C or lower, even more preferably 298°C or lower. As described above, the lower limit values and upper limit values described step by step can be combined independently of each other. For example, from the viewpoint of sufficiently melt-kneading each component, the viewpoint that the storage elastic modulus E' at each of the above temperatures is likely to improve, the viewpoint of more easily obtaining a TPO-based film having better tearability, heat resistance and thermoformability, and the balance with the viewpoint that the flatness and yellowness index (YI) of the TPO-based film are further improved, in one aspect of the present invention, during step (I), the temperature when melting the resin composition is preferably 280 to 323 °C, more preferably 285 to 315 °C, still more preferably 290 to 305 °C, even more preferably 290 to 300 °C, and even more preferably 292 to 298 °C.

[0071] In step (I), after melting the resin composition, the resin composition is extruded, for example, from a die attached to the tip of an extruder and then cooled. The die is not particularly limited as long as the TPO-based film can be produced, but from the viewpoint of easily obtaining a film excellent in production ease and dimensional accuracy, it is preferable to use a T-die. Also, the cooling method is not particularly limited as long as the TPO-based film can be produced, but it is preferable to cool using a casting drum as shown in the following step (II).

[0072] <Step (II)> The manufacturing method preferably includes step (II) of bringing the melt extrudate of the resin composition containing the thermoplastic polyolefin obtained in step (I) as a main component into contact with a casting drum. The temperature of the casting drum is not particularly limited as long as the TPO-based film can be formed, but it is preferably 40°C or higher. From the viewpoint that the storage elastic modulus E' at each of the above temperatures is likely to be improved when the temperature of the casting drum is 40°C or higher, it is also preferable. Further, when the temperature of the casting drum is 40°C or higher, from the viewpoints of more easily obtaining a TPO-based film having better tearability, heat resistance, and thermoformability, and also from the viewpoint that the flatness and yellowness index (YI) of the TPO-based film become even more excellent, it is preferable. From these viewpoints, the temperature of the casting drum is more preferably 50°C or higher, preferably 60°C or higher, still more preferably 80°C or higher, still more preferably 100°C or higher, still more preferably 120°C or higher, still more preferably 140°C or higher, and still more preferably 150°C or higher. Also, when the thermoplastic polyolefin is a 3-methyl-1-butene-based polymer, the higher the temperature of the casting drum, the more likely the values of the elongation at break in the MD direction and the ratio of the elongation at break [MD / TD] are to be larger. Also, from the viewpoint of making film formation easier, such as from the viewpoint of preventing the molten extrudate from adhering to the casting drum, the temperature of the casting drum is preferably 250°C or lower, more preferably 240°C or lower, still more preferably 230°C or lower, still more preferably 220°C or lower, still more preferably 210°C or lower, still more preferably 200°C or lower, and still more preferably 190°C or lower. As described above, the lower limit values and upper limit values described step by step can be combined independently. For example, from the viewpoint of facilitating the improvement of the storage elastic modulus E' at each of the above temperatures, the viewpoint of more easily obtaining a TPO-based film having better tearability, heat resistance, and thermoformability, the viewpoint that the flatness and yellowness index (YI) of the TPO-based film are further improved, and the balance with the viewpoint that the film formability is better, in one aspect of the present invention, during step (II), the temperature of the casting drum is preferably 40 to 250 °C, more preferably 50 to 240 °C, still more preferably 60 to 230 °C, even more preferably 80 to 220 °C, even more preferably 100 to 210 °C, even more preferably 120 to 210 °C, even more preferably 140 to 200 °C, and even more preferably 150 to 190 °C. Here, the "temperature of the casting drum" refers to the temperature of the surface of the casting drum.

[0073] The melt-extruded product that has undergone step (I) is preferably solidified by being cooled through step (II) to obtain the TPO film. Then, if necessary, it may be wound into a roll by a winder or the like. Further, if necessary, further stretching may be performed by a stretching machine or the like.

[0074] Also, as one aspect of the manufacturing method, during step (I), the melt of the resin composition containing the thermoplastic polyolefin as the main component is extruded through a T-die, and the draft ratio [Tt / Ft], which is the ratio of the gap thickness (Tt) of the lip portion of the T-die to the thickness (Ft) of the obtained thermoplastic polyolefin-based film, is preferably 1 to 30 to form the film. When the draft ratio [Tt / Ft] is 1 or more, it is also preferable from the viewpoint that the storage elastic modulus E' at each of the above temperatures is likely to be improved. Further, when the draft ratio [Tt / Ft] is 1 or more, from the viewpoint of more easily obtaining a TPO-based film having better tearability, heat resistance, and thermoformability, and from the viewpoint that the flatness and yellowness index (YI) of the TPO-based film are also more likely to be further improved. Also, within the range where the TPO-based film can be formed, the higher the draft ratio [Tt / Ft], the more likely the elongation at break in the MD direction and the ratio [MD / TD] of the elongation at break will be larger values. From these viewpoints, the draft ratio [Tt / Ft] is more preferably 2 or more, still more preferably 4 or more, even more preferably 8 or more, even more preferably 10 or more, and further, from the viewpoint of better yellowness index (YI) among the above-described characteristics, it is more preferably 14 or more. Also, from the viewpoints of preventing film breakage during film formation and post-processing, more easily suppressing film thickness unevenness, and more easily suppressing shrinkage during thermoforming of the film, etc., the draft ratio [Tt / Ft] is more preferably 28 or less, still more preferably 26 or less, even more preferably 24 or less, even more preferably 22 or less, even more preferably 20 or less. As described above, these stepwise-described lower limit values and upper limit values can be combined independently. For example, in one aspect of the present invention, the draft ratio [Tt / Ft] is preferably 1 to 30, more preferably 2 to 28, still more preferably 4 to 26, even more preferably 8 to 24, even more preferably 10 to 22, even more preferably 14 to 20.

[0075] [Use of Thermoplastic Polyolefin-Based Film] The thermoplastic polyolefin-based film according to one aspect of the present invention, and the thermoplastic polyolefin-based film obtained by the method for producing the thermoplastic polyolefin-based film have good thermoformability and heat resistance. Therefore, it can be used in various applications such as films for film capacitors, films for high-frequency circuit substrates, films for transparent substrates, insulating films, films for thermoforming, optical films, surface protection films, process films, release films, films for sanitary materials, agricultural films, building films, medical films, and the like. Since the TPO-based film is particularly excellent in thermoformability and heat resistance, among these, it can be preferably used as a film for thermoforming. Further, since the TPO-based film also has easy tearability, for example, it can also be preferably used as a film for packaging foods, pharmaceuticals, and sundries, an adhesive tape, and the like.

Examples

[0076] Hereinafter, the present embodiment will be described in more detail with reference to examples, but the present embodiment is not limited to these examples.

[0077] The physical properties of the copolymer (A) obtained in Production Example 1 were measured or evaluated by the following methods.

[0078] [Content ratio of structural units derived from comonomer (1-decene)] The content ratio of structural units derived from 1-decene (comonomer) in the copolymer (A) obtained in Production Example 1 was determined as follows by performing IR measurement by the ATR method using an FT-IR (manufactured by Agilent Technologies, model name "Cary 600 series FTIR spectrometer") as an analyzer. A 3-methyl-1-butene homopolymer and a 1-decene homopolymer were mixed at an arbitrary ratio, and the angular deformation vibration 1,461 cm -1 of the main chain methylene group of each polymer and the angular deformation vibration 727 cm of the side chain methylene group derived from 1-decene -1A calibration curve was created from the ratio to the peak area and the mixing ratio of each resin. The copolymer (A) obtained in Production Example 1 was subjected to the above IR measurement, and the obtained measured value was inserted into the calibration curve to determine the content ratio of the structural unit derived from 1-decene.

[0079] [Melting point] The copolymer (A) obtained in Production Example 1 was heated from 30 °C to 320 °C at 10 °C / min in a nitrogen atmosphere (nitrogen flow rate: 100 mL / min) using a differential scanning calorimeter ("DSC25" manufactured by TA Instruments), held at 320 °C for 5 minutes, and then cooled to -70 °C at 10 °C / min. The peak temperature when heating from -70 °C to 320 °C at 10 °C / min after holding at -70 °C for 5 minutes was measured, and this temperature was defined as the melting point.

[0080] [Melt viscosity] The melt viscosity (Pa·s) of the copolymer (A) obtained in Production Example 1 was measured using a capillary rheometer ("Capillograph (registered trademark) 1C" manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a barrel temperature of 320 °C and a shear rate of 100 sec -1 (Capillary: inner diameter 1.0 mm × length 10 mm, extrusion speed 10 mm / min).

[0081] [Preparation of catalyst] The catalyst components used in Production Example 1 were prepared by the following method. (Preparation of titanium catalyst component) 47.6 g (500 mmol) of anhydrous magnesium chloride, 250 ml of decane and 234 ml (1.5 mol) of 2-ethylhexyl alcohol were heated and reacted at 130 °C for 2 hours to obtain a homogeneous solution. After cooling the obtained homogeneous solution to room temperature (23 °C), it was dropped into 2 L (18 mol) of titanium tetrachloride maintained at -20 °C over 1 hour to obtain a mixed solution. After completion of the dropping of the homogeneous solution, the temperature of the obtained mixed solution was raised to 90 °C over 2 hours. When it reached 90 °C, 11.4 mL (80 mmol) of ethyl benzoate was added and the mixture was kept stirred at the same temperature for 2 hours. After completion of the reaction for 2 hours, the mixture was allowed to stand and then the supernatant was removed. Decane and hexane were added thereto, and the solid content was washed 3 times. Then, it was resuspended in 2 L of titanium tetrachloride and heated and reacted again at 90 °C for 2 hours. After completion of the reaction, decane and hexane were used to allow it to stand again, and the removal of the supernatant was repeated until no free titanium compound was detected in the washing solution. The obtained suspension component was dried under reduced pressure at room temperature for 6 hours to obtain a titanium catalyst component. The composition of the obtained titanium catalyst component was 4.0 mass% of titanium, 56.0 mass% of chlorine, 17.0 mass% of magnesium, 10.4 mass% of ethyl benzoate, and 12.6 mass% of a hydrocarbon solvent composed of decane and hexane.

[0082] [Production Example 1] (Production of Copolymer (A)) Into a 20 L stainless steel autoclave, 8.0 kg of 3-methyl-1-butene, 0.6 kg of 1-decene, 50 g of triethylaluminum diluted with hexane to a concentration of 1 mol / L, and 4 g of the titanium catalyst component prepared in the above [Preparation of Catalyst] were added, and a polymerization reaction was carried out at 70 °C for 4 hours. During the polymerization reaction, hydrogen was continuously supplied at a rate of 40 mL / min. After 4 hours, 200 g of 3-methyl-1-butanol was injected under pressure to stop the reaction and drive out the excess unreacted monomers. Then, 2 kg of normal heptane was introduced, and after stirring at 60 °C for 30 minutes, the solid content was filtered off with a pressure filter. After repeating this operation twice, the solvent was changed from 2 kg of normal heptane to 3 kg of 2-propanol and the same operation was repeated twice. 7.7 kg of the obtained crude polymer was placed in a 50 L container equipped with a stirrer, and then 8 kg of 1 mol / L hydrochloric acid and 16 kg of 2-propanol were added, followed by stirring for 1 hour. This suspension was filtered by vacuum filtration and washed with 10 kg of 2-propanol. The crude polymer obtained from this first washing was placed in a 50 L container equipped with a stirrer, and then 20 kg of 2-propanol was added, followed by stirring for 1 hour. This suspension was filtered by vacuum filtration and washed with 10 kg of 2-propanol. The obtained washed polymer was dried under reduced pressure at 80 °C for 2 days to obtain 3.2 kg of copolymer (A), which is a copolymer of 3-methyl-1-butene and 1-decene. When the above measurements were carried out on the obtained copolymer (A), the melting point was 286 °C and the melt viscosity was 596 Pa·s. Also, the content ratio of the structural unit derived from 1-decene, which is a comonomer, in copolymer (A) was 1.1 mol%.

[0083] [Example 1] To 100 parts by mass of the copolymer (A) obtained in Production Example 1, 0.2 part by mass of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (antioxidant “ADEKA STAB (registered trademark) AO-60”, manufactured by ADEKA CORPORATION), 0.2 part by mass of 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (antioxidant “ADEKA STAB (registered trademark) PEP-36”, manufactured by ADEKA CORPORATION), 0.1 part by mass of 2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate (alkyl radical scavenger “SUMILIZER (registered trademark) GS”, manufactured by Sumitomo Chemical Company, Limited), and 0.25 part by mass of zinc stearate (neutralizing agent) were dry blended. Then, as a measure to prevent oxygen from entering from the outside, nitrogen purge was performed using nitrogen with a purity of 99.99% from the raw material inlet, and while excluding oxygen as much as possible, the dry blended material was charged from the raw material inlet. After melting at a cylinder temperature of 295°C using a twin-screw kneading extruder with a vent “KZW15-45” (manufactured by Technovel Corporation), water was removed by vacuuming using a vacuum pump from the shearing part of the extruder, and a pellet-shaped resin composition (M1) was obtained. Using the obtained pellet-shaped resin composition (M1), molding was performed under the following film-forming conditions to obtain a thermoplastic polyolefin-based film. Specifically, as a measure to prevent oxygen from entering from the outside, nitrogen purge was performed using nitrogen with a purity of 99.99% from the raw material inlet, and while excluding oxygen as much as possible, the above pellet-shaped resin composition (M1) was charged from the raw material inlet. After melting at a cylinder temperature of 295°C using a twin-screw kneading extruder with a vent “KZW15-45” (manufactured by Technovel Corporation), water was removed by vacuuming using a vacuum pump from the shearing part of the extruder, and then melt extrusion was performed in a film form from a T-die (the gap thickness (Tt) of the lip part of the T-die: 300 μm), and solidification was carried out on a casting drum maintained at a surface temperature of 170°C to obtain a thermoplastic polyolefin-based film with a thickness (Ft) of 50 μm. The draft ratio [Tt / Ft] is 6.

[0084] [Examples 2 to 16] A thermoplastic polyolefin film was obtained in the same manner as in Example 1, except that the film-forming conditions were changed as shown in Table 1.

[0085] [Example 17] A thermoplastic polyolefin film was obtained under the same film-forming conditions as in Example 1, except that the pellet-shaped resin composition (M1) was not used and only the copolymer (A) obtained in Production Example 1 was used.

[0086] [Example 18] A thermoplastic polyolefin film was obtained in the same manner as in Example 17, except that nitrogen purging was not performed during film formation.

[0087] [Comparative Example 1] 100 parts by mass of polypropylene (product name "Novatec (registered trademark) PP MA3", manufactured by Japan Polypropylene Corporation), 0.2 parts by mass of pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate] (antioxidant "Adeka STAB (registered trademark) AO-60", manufactured by ADEKA Corporation), 0.2 parts by mass of 3,9-bis (2,6-di-t-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane (antioxidant "Adeka STAB (registered trademark) PEP-36", manufactured by ADEKA Corporation), 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate After dry-blending 0.1 parts by mass of ethyl acetate (alkyl radical scavenger "Sumilizer (registered trademark) GS", manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 parts by mass of zinc stearate (antacid), 0.1 parts by mass of ethyl acetate (alkyl radical scavenger "Sumilizer (registered trademark) GS", manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 parts by mass of zinc stearate (antacid), 0.1 parts by mass of ethyl acetate (alkyl radical scavenger "Sumilizer (registered trademark) GS", manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 parts by mass of ethyl acetate ... Using the obtained pellet-shaped resin composition (CM1), a polypropylene film was obtained by molding under the following film-forming conditions. Specifically, as a measure to prevent oxygen from entering from the outside, nitrogen purging was performed using nitrogen with a purity of 99.99% from the raw material inlet to exclude oxygen as much as possible. Then, the above pellet-shaped resin composition (CM1) was introduced from the raw material inlet. After melting at a cylinder temperature of 240 °C using a twin-screw kneading extruder with a vent "KZW15-45" (manufactured by Technovel Corporation), water was removed by vacuuming using a vacuum pump from the shearing part of the extruder. In a state where water was removed, it was melt-extruded into a film shape from a T-die (the gap thickness (Tt) of the lip part of the T-die: 166.5 μm), and solidified on a casting drum maintained at a surface temperature of 40 °C to obtain a polypropylene film with a thickness (Ft) of 50 μm. The draft ratio [Tt / Ft] was 3.33.

[0088] [Comparative Example 2] A polypropylene film was tried to be formed in the same manner as in Comparative Example 1, except that the surface temperature of the casting drum during film formation was set to 170 °C. However, the film-shaped melt extruded from the T-die fused to the surface of the casting drum, and a polypropylene film could not be formed.

[0089] [Comparative Example 3] 100 parts by mass of polymethylpentene (trade name "TPX (registered trademark) DX845" manufactured by Mitsui Chemicals, Inc.), 0.2 parts by mass of pentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate] (antioxidant "ADEKA STAB (registered trademark) AO-60" manufactured by ADEKA Corporation), 0.2 parts by mass of 3,9-bis (2,6-di-t-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane (antioxidant "ADEKA STAB (registered trademark) PEP-36" manufactured by ADEKA Corporation), 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate After dry-blending 0.1 parts by mass of ethyl acetate (alkyl radical scavenger "Sumilizer (registered trademark) GS", manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 parts by mass of zinc stearate (antacid), ... ethyl acetate (antacid), 0.1 parts by mass of ethyl acetate (alkyl radical scavenger "Sumilizer (registered trademark) GS", manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 parts by mass of ethyl acetate (antacid), 0.1 parts by mass of ethyl acetate (alkyl radical scavenger "Sumilizer (registered trademark) GS", manufactured by Sumitomo Chemical Co., Ltd.) and 0.25 parts by mass of ethyl acetate (antacid), 0.1 parts by mass of ethyl acetate (alkyl radical scavenger "Sumilizer (registered trademark) GS", manufactured by Sumitomo Chemical Co., Ltd.) The obtained pellet-like resin composition (CM2) was molded under the following film-forming conditions to obtain a polymethylpentene film. Specifically, as a measure to prevent oxygen from entering from the outside, nitrogen purging was performed using nitrogen with a purity of 99.99% from the raw material inlet, and while removing oxygen as much as possible, the pellet-like resin composition (CM2) was charged from the raw material inlet, and a vent-equipped twin-screw kneading extruder "KZW15-45" (manufactured by Technobel Co., Ltd.) was used to make it in a molten state at a cylinder temperature of 270°C, and then the shear section of the extruder was evacuated using a vacuum pump to remove moisture, and the melt was extruded into a film shape from a T-die (gap thickness (Tt) of the lip part of the T-die: 166.5 μm), and solidified on a casting drum whose surface temperature was kept at 80°C to obtain a polymethylpentene film with a thickness (Ft) of 50 μm. The draft ratio [Tt / Ft] was 3.33.

[0090] [Comparative Example 4 and Comparative Example 5] A thermoplastic polyolefin film was obtained in the same manner as in Example 18, except that the film-forming conditions were changed as described in Table 1.

[0091] [Comparative Example 6] A thermoplastic polyolefin film was obtained in the same manner as in Example 1, except that the film-forming conditions were changed as described in Table 1.

[0092] [Comparative Example 7] As the thermoplastic polyolefin film, a biaxially stretched cycloolefin polymer film (trade name "ZEONOR Film (registered trademark) L24", manufactured by Zeon Corporation) was used.

[0093] The physical properties of the films obtained in the examples and comparative examples were measured or evaluated by the following methods.

[0094] [Film Thickness] The film was cut into a size of 100 mm in the TD direction × 100 mm in the MD direction from the central part in the TD direction to obtain a film sample. Using a dial gauge type thickness gauge (conforming to JIS B7503 (2017), "PEACOCK (registered trademark) UPRIGHT DIAL GAUGE (scale 0.001 mm, measurement range 2 mm, model No. 25, measuring head 5 mmφ flat type)" manufactured by Ozaki Seisakusho Co., Ltd.), the thickness was measured at 11 points at intervals of 10 mm from both ends of the film in the TD direction, and the average value was taken as the film thickness. Note that the MD direction (abbreviation for Machine Direction) corresponds to the longitudinal direction of the film parent roll during film formation. Also, the TD direction (abbreviation for Transverse Direction) refers to the direction perpendicular to the MD direction. The same applies hereinafter.

[0095] [Storage Elastic Modulus E'] Based on JIS K7244-1:1998, the storage modulus E' of the film at each temperature (70°C, 150°C, 270°C) was determined using the dynamic viscoelasticity measuring device "Rheogel-E4000" manufactured by UBM Co., Ltd. The measurement was carried out only in the MD direction of the film under the following conditions, and the average value of the results of three measurements was taken as the storage modulus E' of the film. · Measurement method: Dynamic viscoelasticity measurement (sinusoidal wave) · Measurement mode: Temperature dependence · Chuck: Tensile · Waveform: Sinusoidal wave · Vibration type: Stop vibration · Distance between chucks: 10 mm · Width of test piece: 5 mm · Frequency: 1 Hz · Measurement temperature: From -50°C to 300°C · Heating rate: 3°C / min · Measurement atmosphere: Under air

[0096] [Heat resistance] The film was cut into a size of 100 mm × 100 mm to obtain a film sample, and the film sample was left in a state without applying a load from above under the atmospheric conditions of a temperature of 25°C and a relative humidity of 65% for 24 hours to condition the film sample. After leaving the conditioned film sample in a hot air oven at 240°C for 30 minutes and then taking it out, and leaving it for 30 minutes or more under the atmospheric conditions of a temperature of 23°C and a relative humidity of 50%, the change in the appearance of the film sample before and after being put into the hot air oven was visually evaluated according to the following evaluation criteria. The judgment result "S" is the most excellent. Also, if the judgment results are "A" or "B", it was judged that the film has good heat resistance. [Judgment: Criteria] "S": No obvious change is seen in the appearance of the film. "A": Slight changes (such as curling, unevenness, swelling, etc.) are seen in the film. "B": Changes (such as curling, unevenness, swelling, etc.) larger than those in judgment "A" are seen in the film. "C": Obvious changes (such as curling, unevenness, swelling, etc.) larger than those in judgment "B" are seen in the film. "D": A change greater than that of determination "C" is observed, such as the film melting or significantly shrinking.

[0097] [Thermoformability] In accordance with the following method specified in ASTM-D882, using a precision universal testing machine (Shimadzu Corporation, Autograph (registered trademark) "AG-2000B"), a film sample with a width of 10 mm was set so that the length between chucks was 50 mm, held in a thermostatic bath adjusted to a temperature of 210 °C in advance for 20 seconds, and then a tensile test was conducted at 210 °C and a tensile speed of 100 mm / min. The elongation at break at 210 °C was measured 5 times in the MD direction of the film, and the average of the 5 measurement results was taken as the elongation at break in the MD direction of the film, which was evaluated as an index of thermoformability at high temperatures. The judgment result "S" is the best. Also, if the judgment results are "A" or "B", it is a film with good thermoformability, and a film with a judgment result of "A" has better thermoformability than "B". 〔Measurement conditions〕 · Film sample size: width 10 mm × length 100 mm (the length direction corresponds to the MD direction) · Distance between chucks: 50 mm · Tensile speed: 100 mm / min 〔Judgment: Criteria〕 "S": Has an elongation at break of 200% or more. "A": Has an elongation at break of 100% or more. "B": Has an elongation at break of 10% or more and less than 100%. "C": Has an elongation at break of less than 10%, or measurement was difficult for the following reasons. The curl of the film sample was large and the film could not be set on the measurement chuck, or the film adhered to the measurement chuck.

[0098] [Planarity (curl degree)] The film was cut into a size of 100 mm × 100 mm to obtain a film sample, and the film sample was left for 24 hours under atmospheric conditions of a temperature of 25°C and a relative humidity of 65% without applying a load from above, and the humidity conditioning of the film sample was performed. After the humidity conditioning, the film sample was placed on a table with good flatness without being fixed at the four sides with tape (assuming the casting drum surface of the film sample is the surface in contact with the table), and the "lifting" of the film from above the table was measured to evaluate the flatness. Also, the "lifting" refers to setting the contact surface between the table and the film as 0 mm, and the height (distance) from the contact surface to the most lifted part of the film placed on the table, and this "lifting" was taken as the value (unit: mm) of the "curl degree", which is an index for evaluating flatness. The smaller the value of the curl degree, the better the flatness.

[0099] [Transmittance YI (D65)] The yellowness index (YI value) of the film was measured using a spectrophotometer "SD7000" manufactured by Nippon Denshoku Industries Co., Ltd. under the conditions of a D65 light source (viewing angle 10 degrees). After performing background measurement in the absence of a sample, the film was set in a sample holder, and the transmittance measurement for light from 380 nm to 780 nm was performed to obtain the three stimulus values (X, Y, Z). The YI value was calculated based on the following formula. Three measurements were performed, and the average of the results of each three measurements was taken as the yellowness index (YI value) of the film. This value was taken as the transmittance YI (D65) and is shown in Table 1 below. The smaller the value of the yellowness index (YI value) of the film, the better it is. YI = 100×(1.2769X - 1.0592Z) / Y

[0100] [Elongation at break and elongation ratio [MD / TD]] According to the following method specified in ASTM-D882, using a precision universal testing machine ("Autograph (registered trademark) AGS-X" manufactured by Shimadzu Corporation), a film sample with a width of 10 mm was set so that the length between chucks was 50 mm, and a tensile test was performed at a tensile speed of 100 mm / min under atmospheric conditions of a temperature of 23°C and a relative humidity of 50%. The breaking point elongation was measured five times in the MD direction of the film, and the average of the five measurement results was taken as the breaking point elongation in the MD direction. Also, the film TD direction was measured five times, and the average of the five measurement results was taken as the breaking point elongation in the TD direction. Also, using the obtained results, the ratio [MD / TD] of the breaking point elongation in the MD direction to the breaking point elongation in the TD direction was calculated. 〔Measurement conditions〕 · Film sample size: width 10 mm × length 100 mm (the length direction corresponds to the MD direction) · Distance between chucks: 50 mm · Tensile speed: 100 mm / min

[0101] [Ease of tearing of the film] The film was cut into a size of 100 mm × 100 mm to obtain a film sample. The film sample was folded in half so that a crease was formed in the MD direction, and then it was torn by hand along the crease in the MD direction of the film. The feeling of tearing by hand was judged according to the following criteria. The judgment result of "S" is the best. Also, if the judgment results are "A", "B", or "C", it is a film with good ease of tearing. Among them, the film with the judgment result of "A" has better ease of tearing than "B", and the film with the judgment result of "B" has better ease of tearing than "C". 〔Judgment: Criteria〕 "S": It could be easily torn by hand without any particular resistance. "A": There was resistance, but it could be torn. "B": There was more resistance than "A", but it could be torn with a little force. "C": There was more resistance than "B", and it could be torn with great effort. "D": It could not be torn. Or cracks occurred when it was folded in half, making it impossible to evaluate the ease of tearing of the film.

[0102]

Table 1

[0103]

Table 2

[0104] In Table 2, the notation “(*1)” indicates that the film-like melt after extrusion fused to the casting drum, making it impossible to form a film and thus unable to be evaluated. Also, in Tables 1 and 2, the following abbreviations in the “Resin Composition” column represent the following matters respectively. P3MB(100): In 100% by mass of the total polymer in the resin composition, the 3-methyl-1-butene-based polymer is 100% by mass. PP(100): In 100% by mass of the total polymer in the resin composition, polypropylene is 100% by mass. TPX(100): In 100% by mass of the total polymer in the resin composition, polymethylpentene is 100% by mass. Biaxially stretched COP(100): Biaxially stretched cycloolefin polymer film. Also, in Tables 1 and 2, “Antioxidant, etc.” refers to antioxidants, alkyl radical scavengers, and antacids. Therefore, the notation “present” for “Antioxidant, etc.” in each example indicates that each antioxidant, alkyl radical scavenger, and antacid used in Example 1 is similarly included. On the other hand, the notation “absent” for “Antioxidant, etc.” in Examples 17 and 18, and Comparative Examples 4 and 5 indicates that all of the antioxidant, alkyl radical scavenger, and antacid are not included.

[0105] From the results in Table 1, the thermoplastic polyolefin films of Examples 1 to 18 are formed from a resin composition containing a thermoplastic polyolefin as a main component, the elongation at break in the MD direction is 10.0% or more, and the ratio of the elongation at break in the MD direction to the elongation at break in the TD direction [MD / TD] is 2.0 to 30.0. Therefore, it was confirmed that they have good tearability compared to the thermoplastic polyolefin films of each comparative example. Furthermore, since the storage modulus E' at 270°C of the thermoplastic polyolefin films of Examples 1 to 18 is 1 MPa or more, it was confirmed that they exhibit good heat resistance and thermoformability as compared to the thermoplastic polyolefin films of each Comparative Example.

[0106] From the results in Table 2, the thermoplastic polyolefin films of Comparative Examples 1, 3, and 7 have a ratio of the elongation at break in the MD direction to the elongation at break in the TD direction [MD / TD] of less than 2.0. Therefore, it was confirmed that they are inferior in tearability as compared to the thermoplastic polyolefin films of each Example. Furthermore, since the storage modulus E' at 270°C of the thermoplastic polyolefin films of Comparative Examples 1, 3, and 7 is less than 1 MPa, it was confirmed that they are inferior in both heat resistance and thermoformability as compared to the thermoplastic polyolefin films of each Example. Also, for Comparative Examples 4 to 6, since the elongation at break in the MD direction is less than 10.0%, it was confirmed that they are inferior in tearability as compared to the thermoplastic polyolefin films of each Example. Furthermore, since the storage modulus E' at 270°C of the thermoplastic polyolefin films of Comparative Examples 4 to 6 is less than 1 MPa, it was confirmed that they are inferior in both heat resistance and thermoformability as compared to the thermoplastic polyolefin films of each Example. Regarding Comparative Example 2, as described above, when the surface temperature of the casting drum during film formation was set to 170°C, the film-like melt extruded from the T-die fused to the surface of the casting drum, and the film could not be formed.

Claims

1. A thermoplastic polyolefin-based film formed from a resin composition containing a thermoplastic polyolefin as a main component, having an elongation at break in the MD direction of 10.0% or more, a ratio [MD / TD] of the elongation at break in the MD direction to the elongation at break in the TD direction of 2.0 to 30.0, and a storage elastic modulus E' at 270 °C of 1 MPa or more.

2. The thermoplastic polyolefin-based film according to claim 1, wherein the storage elastic modulus E' at 70 °C is 1,000 MPa or less.

3. The thermoplastic polyolefin-based film according to claim 1 or 2, wherein the storage elastic modulus E' at 150 °C is 50 to 500 MPa.

4. The thermoplastic polyolefin-based film according to claim 1 or 2, wherein the storage elastic modulus E' at 270 °C is 1 to 100 MPa.

5. The thermoplastic polyolefin-based film according to claim 2, wherein the storage elastic modulus E' at 70 °C is 100 to 1,000 MPa.

6. The thermoplastic polyolefin-based film according to claim 1 or 2, having a yellowness index (YI) of 3.50 or less.

7. The thermoplastic polyolefin-based film according to claim 1 or 2, wherein the thermoplastic polyolefin is an aliphatic polyolefin.

8. The thermoplastic polyolefin-based film according to claim 1 or 2, wherein the thermoplastic polyolefin is a 3-methyl-1-butene-based polymer.

9. The thermoplastic polyolefin-based film according to claim 8, wherein the 3-methyl-1-butene-based polymer is at least one selected from the group consisting of a 3-methyl-1-butene homopolymer and at least one copolymer of 3-methyl-1-butene and at least one selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms other than 3-methyl-1-butene.

10. The thermoplastic polyolefin-based film according to claim 8, wherein the content of the 3-methyl-1-butene-based polymer is 50.0% by mass or more based on 100% by mass of the total amount of the resin composition.

11. The thermoplastic polyolefin-based film according to claim 1 or 2, wherein the resin composition contains an antioxidant.

12. The thermoplastic polyolefin-based film according to claim 11, wherein the antioxidant is at least one selected from the group consisting of a phenolic antioxidant and a phosphorus-based antioxidant.

13. including a step (I) of melt-extruding a resin composition containing a thermoplastic polyolefin as a main component; A method for producing a thermoplastic polyolefin-based film, which comprises producing a thermoplastic polyolefin-based film having an elongation at break in the MD direction of 10.0% or more, a ratio [MD / TD] of the elongation at break in the MD direction to the elongation at break in the TD direction of 2.0 to 30.0, and a storage elastic modulus E' at 270 °C of 1 MPa or more.

14. The method for producing a thermoplastic polyolefin-based film according to claim 13, wherein, in the step (I), the resin composition containing the thermoplastic polyolefin as a main component is melted in an inert atmosphere or in a low-oxygen state.

15. The method for producing a thermoplastic polyolefin-based film according to claim 13 or 14, wherein, in the step (I), the resin composition containing the thermoplastic polyolefin as a main component is melted at 280 to 323 °C.

16. The method for producing a thermoplastic polyolefin-based film according to claim 13 or 14, including a step (II) of bringing the melt extrudate of the resin composition containing the thermoplastic polyolefin as a main component obtained in the step (I) into contact with a casting drum, wherein the temperature of the casting drum is 40 to 250 °C.

17. The method for producing a thermoplastic polyolefin-based film according to claim 13 or 14, wherein, in the step (I), the melt of the resin composition containing the thermoplastic polyolefin as a main component is extruded through a T-die, and the draft ratio [Tt / Ft], which is the ratio of the gap thickness (Tt) of the lip portion of the T-die to the thickness (Ft) of the obtained thermoplastic polyolefin-based film, is 1 to 30.

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