JP7828762B2 - Film and method for manufacturing the same - Google Patents

Description

This invention relates to a film containing a 4-methyl-1-pentene polymer and a method for producing the same.

4-methyl-1-pentene polymers possess superior characteristics compared to polyethylene and polypropylene, including heat resistance, transparency, light weight, steam resistance, release properties, stain resistance, gas permeability, and electrical properties. They are used in a wide range of applications, including food containers, auxiliary materials for electronic and information components, laboratory equipment, stationery, crosslinking process components, release films, films for electronic and information components, food packaging, and synthetic paper.

The cast film method is a known method for producing films using 4-methyl-1-pentene polymers. However, the cast film method has several drawbacks, including the fact that it can only produce flat films or sheets, and that the thickness of the edges tends to be uneven, resulting in a low yield because the uneven portions (edges) must be trimmed off.
Therefore, there was a need for a film containing a 4-methyl-1-pentene polymer and having a uniform thickness, and in particular, an inflation film containing a 4-methyl-1-pentene polymer was in demand.

Patent Document 1 describes a method for producing an inflation film using a 4-methyl-1-pentene polymer by extruding molten resin upward from an inflation die at a temperature 25 to 65°C higher than the melting point.

Patent Document 2 proposes a technique for improving the stretchability of 4-methyl-1-pentene polymers using a resin composition containing two types of 4-methyl-1-pentene polymers with different melt flow rates (MFRs). It demonstrates that blow molding using a mold is possible with this resin composition.

Japanese Patent Publication No. 2001-62869 Japanese Patent Publication No. 2003-292704

However, since 4-methyl-1-pentene polymers generally have poor stretchability, even if the manufacturing method described in Patent Document 1 is adopted, the inflation film obtained by inflation film molding involving stretching has the problem of being prone to variations in film thickness.
Furthermore, even if blow molding is possible with the resin composition described in Patent Document 2, the bubble stability is insufficient, and further improvements are needed to form an inflation film with a uniform thickness.

The present invention aims to provide a film containing a 4-methyl-1-pentene polymer, exhibiting minimal variation in film thickness, good film thickness accuracy (thickness/thinness precision), and heat resistance. Furthermore, the present invention aims to provide a film manufacturing method by inflation molding that offers excellent bubble stability, enables stable molding, and allows for the production of thin films containing a 4-methyl-1-pentene polymer with superior film thickness accuracy.

In view of these circumstances, the inventors conducted thorough research and found that a film containing a specific 4-methyl-1-pentene polymer composition can solve the above problems, thus concluding the present invention.
The present invention relates, for example, to the following matters [1] to [9].

[1] A film characterized by containing a 4-methyl-1-pentene polymer composition (X) that satisfies the following requirements (X-1) to (X-4).
Requirement (X-1): Density measured in accordance with JIS K7112 (density gradient pipe method) is 0.82 to 0.88 g/ ^m³ .
Requirement (X-2): The melting point (Tm) measured by differential scanning calorimetry (DSC) is between 190°C and 250°C.
Requirement (X-3): Melting enthalpy ΔH is less than 35 J/g.
Requirement (X-4): The semi-crystallization time at 215°C, measured by DSC using the following measurement method, is 220 seconds or longer, or is not measured.
Method for measuring semi-crystallization time: Using a PerkinElmer DSC8500, the temperature is raised from 30°C to 280°C at a heating rate of 500°C/min, the temperature is maintained for 10 minutes, and then the temperature is lowered to 215°C at a cooling rate of 500°C/min. The semi-crystallization time at 215°C is then measured.

[2] The film according to [1], wherein the 4-methyl-1-pentene polymer composition (X) satisfies the following requirements (X-5) and (X-6).
Requirement (X-5): The content of constituent units derived from 4-methyl-1-pentene is 90.0 mol% or more and less than 100 mol%, and the content of constituent units derived from ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is greater than 0 mol% and 10.0 mol% or less.
Requirement (X-6): The intrinsic viscosity [η] measured in decalin at 135°C is 1.5 to 8.0 dl/g.

[3] The film according to [1] or [2], wherein the 4-methyl-1-pentene polymer composition (X) satisfies the following requirement (X-7).
Requirement (X-7): The melt tension (MT) measured at 260°C is 25 mN or greater.

[4] A film according to any one of [1] to [3], having an average thickness of 0.1 to 100 μm.
[5] An inflation film, the film described in any of [1] to [4].
[6] A film for packaging purposes, as described in any of [1] to [5].

[7] A method for producing a film, characterized by comprising a step of inflation molding a 4-methyl-1-pentene polymer composition (X) that satisfies the following requirements (X-1) to (X-4).
Requirement (X-1): Density measured in accordance with JIS K7112 (density gradient pipe method) is 0.82 to 0.88 g/ ^m³ .
Requirement (X-2): The melting point (Tm) measured by differential scanning calorimetry (DSC) is between 190°C and 250°C.
Requirement (X-3): Melting enthalpy ΔH is less than 35 J/g.
Requirement (X-4): The semi-crystallization time at 215°C, measured by DSC using the following measurement method, is 220 seconds or longer, or is not measured.
Method for measuring semi-crystallization time: Using a PerkinElmer DSC8500, the temperature is raised from 30°C to 280°C at a heating rate of 500°C/min, the temperature is maintained for 10 minutes, and then the temperature is lowered to 215°C at a cooling rate of 500°C/min. The semi-crystallization time at 215°C is then measured.

[8] The method for manufacturing a film according to [7], wherein the expansion ratio (bubble ratio) during inflation molding exceeds 1.0.
A method for manufacturing a film according to [7] or [8], which involves manufacturing a film according to any of [9], [1] to [6].

According to the present invention, it is possible to provide a film containing a 4-methyl-1-pentene polymer, exhibiting minimal variation in film thickness, excellent film thickness accuracy (thickness/thinness precision), and heat resistance. Furthermore, according to the present invention, it is possible to provide a film manufacturing method that offers excellent bubble stability, enables stable molding, and produces a thin film containing a 4-methyl-1-pentene polymer with excellent film thickness accuracy. In particular, it is possible to provide a film manufacturing method using inflation film molding accompanied by stretching.

The film of the present invention comprises a 4-methyl-1-pentene polymer composition (X).
<4-methyl-1-pentene polymer composition (X)>
The 4-methyl-1-pentene polymer composition (X) according to the present invention comprises at least one 4-methyl-1-pentene polymer. In the present invention, a 4-methyl-1-pentene polymer is a polymer or copolymer having a structural unit derived from 4-methyl-1-pentene, and is a homopolymer of 4-methyl-1-pentene or a copolymer of a monomer copolymerizable with 4-methyl-1-pentene. Preferably, the copolymer is a copolymer of 4-methyl-1-pentene and one or more olefins selected from ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene).

Examples of the above-mentioned α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, and 1-eicosene. Among ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene), α-olefins having 10 to 20 carbon atoms are preferred, and α-olefins having 10 to 18 carbon atoms are more preferred, from the viewpoint of obtaining polymer compositions with good moldability. Specifically, 1-decene, 1-tetradecene, 1-hexadecene, and 1-octadecene are preferred. Furthermore, for example, it is preferable to use 1-hexadecene and 1-octadecene together.

In 4-methyl-1-pentene polymers, the content ratio of constituent units derived from ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is such that the amount of constituent units in the entire 4-methyl-1-pentene polymer contained in the 4-methyl-1-pentene polymer composition (X) described later is within a desired range, and there is no need to limit the individual polymers. However, out of 100 mol% of the total constituent units constituting the 4-methyl-1-pentene polymer, the content ratio is usually 20 mol% or less, preferably 10 mol% or less, more preferably 0.1 to 10 mol%, and even more preferably 0.2 to 8 mol%.
Furthermore, the proportion of constituent units derived from 4-methyl-1-pentene in the total constituent units of the 4-methyl-1-pentene polymer is usually 80 mol% or more, preferably 90 mol% or more.

The 4-methyl-1-pentene polymer may further have constituent units derived from other polymerizable compounds other than 4-methyl-1-pentene, ethylene, and C3-20 α-olefins (excluding 4-methyl-1-pentene), to the extent that it does not impair the objectives of the present invention. Other polymerizable compounds include, for example, vinyl compounds having a cyclic structure such as styrene, vinylcyclopentene, vinylcyclohexane, and vinylnorbornane; vinyl esters such as vinyl acetate; unsaturated organic acids or their derivatives such as maleic anhydride; conjugated dienes such as butadiene, isoprene, pentadiene, and 2,3-dimethylbutadiene; 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and 7-methyl-1,6-octadiene. Examples of non-conjugated polyenes include dicyclopentadiene, cyclohexadiene, dicyclooctadiene, methylenenorbornene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, and 2-propenyl-2,2-norbornadiene.

In 4-methyl-1-pentene polymers, the content of constituent units derived from polymerizable compounds other than 4-methyl-1-pentene, ethylene, and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is usually 10 mol% or less, preferably 5 mol% or less, and more preferably 3 mol% or less, out of 100 mol% of the total constituent units constituting the copolymer.
4-methyl-1-pentene polymers can be produced, for example, by the method for producing 4-methyl-1-pentene polymers described later. Alternatively, commercially available 4-methyl-1-pentene polymers can be used alone or in combination, as long as the 4-methyl-1-pentene polymer composition (X) satisfies the properties described later.

The 4-methyl-1-pentene polymer composition (X) according to the present invention may contain one of the above-mentioned 4-methyl-1-pentene polymers alone, or it may contain two or more in combination.

Method for producing 4-methyl-1-pentene polymers The 4-methyl-1-pentene polymer constituting the 4-methyl-1-pentene polymer composition (X) can be obtained, for example, by polymerizing 4-methyl-1-pentene with ethylene and an α-olefin having 3 to 20 carbon atoms as needed, and further optionally with the other polymerizable monomers. The 4-methyl-1-pentene polymer constituting the 4-methyl-1-pentene polymer composition (X) of the present invention can be suitably produced by carrying out the polymerization in the presence of a metallocene catalyst.

Examples of metallocene catalysts include those described in International Publication No. 01/53369, International Publication No. 01/27124, Japanese Patent Publication No. 3-193796, Japanese Patent Publication No. 02-41303, International Publication No. 06/025540, or International Publication No. 2013/099876.

Examples of metallocene catalysts include,
Metallocene compound (a) and
Examples include catalysts composed of at least a support (b).

Metallocene compounds (a)
The metallocene compound (a) is represented, for example, by general formula (1) or (2).

The meanings of each symbol in general formula (1) or (2) are as follows:
^R1 to ^R14 are each independently a hydrogen atom, a hydrocarbon group, a substituted hydrocarbon group, or a silicon-containing group. Adjacent substituents ^R1 to ^R4 may bond to each other to form a ring. Adjacent substituents ^R5 to ^R12 may bond to each other to form a ring.

Y is a carbon or silicon atom.
A is a divalent hydrocarbon group having 2 to 20 carbon atoms, which may contain unsaturated bonds and/or aromatic rings. A may contain two or more ring structures, including a ring formed with Y.

M is a metal (transition metal) selected from Group 4 of the periodic table, such as titanium, zirconium, and hafnium.
Q is a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an anionic ligand, or a neutral ligand that can coordinate with a lone pair of electrons. When j is 2 or greater, each Q may be the same or different.
j is an integer between 1 and 4, preferably 2.

Examples of hydrocarbon groups in ^R1 to ^R14 include hydrocarbon groups having 1 to 20 carbon atoms, specifically alkyl groups having 1 to 20 carbon atoms, cycloalkyl groups having 3 to 20 carbon atoms, arylalkyl groups having 7 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, and alkylaryl groups having 7 to 20 carbon atoms.

The substituted hydrocarbon groups in ^R1 to ^R14 (excluding silicon-containing groups) are groups in which some or all of the hydrogen atoms contained in the hydrocarbon group are replaced by functional groups such as halogen atoms (fluorine, chlorine, bromine, iodine), hydroxyl groups, and amino groups.

Examples of silicon-containing groups in ^R1 to ^R14 include alkylsilyl groups or arylsilyl groups having 1 to 4 silicon atoms and 3 to 20 carbon atoms. Specific examples include trimethylsilyl, tert-butyldimethylsilyl, and triphenylsilyl.

Adjacent substituents ^R5 to ^R12 on the fluorene ring may bond to each other to form a ring. Examples of such substituted fluorenyl groups include benzofluorenyl, dibenzofluorenyl, octahydrodibenzofluorenyl, and octamethyloctahydrodibenzofluorenyl.

For ease of synthesis, the substituents ^R5 to ^R12 on the fluorene ring are preferably symmetrical, i.e., ^R5 = ^R12 , ^R6 = ^R11 , ^R7 = ^R10 , and ^R8 = ^R9 . The fluorene ring portion is preferably unsubstituted fluorene, 3,6-disubstituted fluorene, 2,7-disubstituted fluorene, or 2,3,6,7-tetrasubstituted fluorene. The 3, 6, 2, and 7 positions on the fluorene ring correspond to ^R7 , ^R10 , ^R6 , and ^R11 , respectively.
^R13 and ^R14 are preferably each independently a hydrogen atom, a hydrocarbon group, or a substituted hydrocarbon group.

In the case of general formula (1), R ¹³ and R ¹⁴ bond with Y, forming a substituted methylene group or a substituted silylene group as a crosslinking portion. Specific examples of substituted methylene groups and substituted silylene groups include, for example, dialkylmethylene, dicycloalkylmethylene, alkylcycloalkylmethylene, alkylarylmethylene, diarylmethylene, dialkylsilylene, dicycloalkylsilylene, alkylcycloalkylsilylene, alkylarylsilylene, diarylmethylene, and halogenated groups of these groups.

In the case of general formula (2), Y is bonded to the divalent hydrocarbon group A, forming a cycloalkylidene group or a cyclomethylenesilylene group, etc. Specific examples of cycloalkylidene and cyclomethylenesilylene groups include, for example, cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclohexylidene, cycloheptylidene, bicyclo[3.3.1]nonylidene, norbornylidene, adamantylidene, tetrahydronaphthylidene, dihydroindanylidene, cyclodimethylenesilylene, cyclotrimethylenesilylene, cyclotetramethylenesilylene, cyclopentamethylenesilylene, cyclohexamethylenesilylene, and cycloheptamethylenesilylene.

In Q, examples of halogen atoms include fluorine, chlorine, bromine, and iodine; examples of hydrocarbon groups having 1 to 20 carbon atoms include groups similar to those of the hydrocarbon groups ^R1 to ^R14 ; examples of anionic ligands include alkoxy groups, allyloxy groups, carboxylate groups, sulfonate groups, etc.; examples of neutral ligands that can coordinate with lone pairs of electrons include organophosphorus compounds such as trimethylphosphine, triethylphosphine, triphenylphosphine, and diphenylmethylphosphine, and ethers such as tetrahydrofuran, diethyl ether, dioxane, and 1,2-dimethoxyethane. Preferably, at least one of Q is a halogen atom or an alkyl group having 1 to 20 carbon atoms.

Specific examples of metallocene compounds (a) include, for example, the compounds exemplified in International Publication No. 01/27124, International Publication No. 2006/025540, or International Publication No. 2007/308607.

The metallocene compound (a) is particularly preferably the compound represented by the following general formula (3), as described in International Publication No. 2014/050817, etc.

In general formula (3), ^R1b is a hydrocarbon group, a silicon-containing group, or a halogen-containing hydrocarbon group, ^R2b to ^R12b are selected from a hydrogen atom, a hydrocarbon group, a silicon-containing group, a halogen atom, and a halogen-containing hydrocarbon group, and may be the same or different, and each substituent may be bonded to each other to form a ring. M is a transition metal of group 4 of the periodic table, n is an integer from 1 to 3, Q is the same as Q in general formula (1) or (2), and j is an integer from 1 to 4.

Examples of hydrocarbon groups in ^R1b to ^R12b include linear hydrocarbon groups such as linear alkyl groups and linear alkenyl groups; branched hydrocarbon groups such as branched alkyl groups; cyclic saturated hydrocarbon groups such as cycloalkyl groups, norbornyl groups, and adamantyl groups; cyclic unsaturated hydrocarbon groups such as aryl groups and cycloalkenyl groups; and groups such as aralkyl groups, which are formed by substituting one or more hydrogen atoms of a saturated hydrocarbon group with a cyclic unsaturated hydrocarbon group. The number of carbon atoms in the hydrocarbon group is usually 1 to 20, preferably 1 to 15, and more preferably 1 to 10.

Examples of silicon-containing groups in ^R1b to ^R12b include groups represented by the formula _-SiR3 (wherein each of the multiple Rs is independently an alkyl group having 1 to 15 carbon atoms or a phenyl group).

Examples of halogen-containing hydrocarbon groups in ^R1b to ^R12b include groups such as trifluoromethyl groups, which are formed by substituting one or more hydrogen atoms of the above-mentioned hydrocarbon group with halogen atoms.
Examples of halogen atoms in ^R2b to ^R12b include fluorine, chlorine, bromine, and iodine.

Examples of rings formed by the bonding of two substituents in general formula (3) (spiro rings, additional rings) include alicyclic rings and aromatic rings. Specifically, examples include cyclohexane rings, benzene rings, hydrogenated benzene rings, and cyclopentene rings, with cyclohexane rings, benzene rings, and hydrogenated benzene rings being preferred. Furthermore, such ring structures may have additional substituents such as alkyl groups on the ring.

^R1b is particularly preferably a substituent in which the carbon with free valence (the carbon bonded to the cyclopentadienyl ring) is a tertiary carbon. Specifically, ^R1b can be a tert-butyl group, a tert-pentyl group, a 1-methylcyclohexyl group, or a 1-adamantyl group.
The fluorene ring portion is not particularly limited as long as it is a structure obtained from known fluorene derivatives, but ^R4b and ^R5b are preferably hydrogen atoms from the viewpoint of molecular weight.

^R2b , ^R3b , ^R6b , and ^R7b are preferably hydrocarbon groups having 1 to 20 carbon atoms. Alternatively, ^R2b and ^R3b may bond to each other to form a ring, and ^R6b and ^R7b may also bond to each other to form a ring. Examples of such substituted fluorenyl groups include benzofluorenyl group, dibenzofluorenyl group, octahydrodibenzofluorenyl group, 1,1,4,4,7,7,10,10-octamethyl-2,3,4,7,8,9,10,12-octahydro-1H-dibenzo[b,h]fluorenyl group, 1,1,3,3,6,6,8,8-octamethyl-2,3,6,7,8,10-hexahydro-1H-dicyclopenta[b,h]fluorenyl group, and 1',1',3',6',8',8'-hexamethyl-1'H,8'H-dicyclopenta[b,h]fluorenyl group.

^R8b is preferably a hydrogen atom. ^R9b is preferably an alkyl group having two or more carbon atoms. Furthermore, from a synthetic standpoint, ^R10b and ^R11b are also preferably hydrogen atoms.
Alternatively, when n=1, it is more preferable that ^R9b and ^R10b are bonded to each other to form a ring, and it is particularly preferable that this ring is a six-membered ring such as a cyclohexane ring. In this case, it is preferable that ^R11b is a hydrogen atom.
^R12b is preferably an alkyl group.

M is a transition metal of Group 4 of the periodic table, such as Ti, Zr, or Hf, preferably Zr or Hf, and particularly preferably Zr.

n is an integer from 1 to 3, preferably 1 or 2, and more preferably 1. The above values for n are preferable from the viewpoint of efficiently obtaining the resulting polymer.
j is an integer from 1 to 4, preferably 2.

The compound represented by general formula (3) is particularly preferably (8-octamethylfluoren-12'-yl-(2-(adamantan-1-yl)-8-methyl-3,3b,4,5,6,7,7a,8-octahydrocyclopenta[a]indene))zirconium dichloride or (8-(2,3,6,7-tetramethylfluoren)-12'-yl-(2-(adamantan-1-yl)-8-methyl-3,3b,4,5,6,7,7a,8-octahydrocyclopenta[a]indene))zirconium dichloride. Here, octamethylfluoren refers to 1,1,4,4,7,7,10,10-octamethyl-2,3,4,7,8,9,10,12-octahydro-1H-dibenzo[b,h]fluorene.

《Carrier (b)》
The support (b) is preferably in particulate form, and the metallocene catalyst is formed by immobilizing the metallocene compound (a) on its surface and inside. Catalysts of this form are generally called metallocene-supported catalysts.
The carrier (b) mainly consists of an organoaluminum compound (b-1), an organoboron compound (b-2), or an inorganic compound (b-3), or a composite of two or more compounds selected from these.

Examples of organoaluminum compounds (b-1) include trialkylaluminum compounds such as trimethylaluminum, triethylaluminum, triisobutylaluminum, and trin-normal octylaluminum; dialkylaluminum hydrides such as diisobutylaluminum hydride; tricycloalkylaluminum; and organoaluminum oxy compounds represented by aluminoxanes. Furthermore, examples of organoaluminum compounds (b-1) include organoaluminum oxy compounds containing boron atoms, halogen-containing aluminoxanes as exemplified in International Publication No. 2005/066191 and International Publication No. 2007/131010, and ionic aluminoxanes as exemplified in International Publication No. 2003/082879.

Examples of organoboron compounds (b-2) include trialkylammonium tetraarylborate, trialkylammonium tetra(aryl halide)borate, dioctadecylmethylammonium tetraarylborate, dioctadecylmethylammonium tetra(aryl halide)borate, N,N-dialkylanilinium tetraarylborate, and N,N-dialkylanilinium tetra(aryl halide)borate.

Examples of inorganic compounds (b-3) include porous oxides, inorganic halides, clays _{, clay minerals, or ion-exchangeable layered compounds. Examples of porous oxides include oxides of SiO₂, Al₂O₃, MgO, ZrO₂, TiO₂, B₂O₃ , CaO , ZnO , BaO} , _ThO₂ , etc., or composites or mixtures containing these. Examples include natural or synthetic zeolites, _SiO₂ -MgO, _SiO₂ - _Al₂O₃ , SiO₂- _TiO₂ , _SiO₂ - _V₂O₅ , _{SiO₂ - Cr₂O₃} , _SiO₂ - _{TiO₂ -} MgO, _etc. Examples of inorganic halides include _MgCl₂ , _MgBr₂ , _MnCl₂ , _{and MnBr₂} . Inorganic halides may be used as is, or they may be used after being ground using a ball mill or vibration mill. Alternatively, an inorganic halide can be dissolved in a solvent such as alcohol, and then precipitated into fine particles using a precipitating agent.

As the support (b), a support containing aluminum atoms is preferred from the viewpoint of high activity and further suppression of the solvent-soluble portion. The aluminum atom content in support (b) is preferably 20% by mass or more, more preferably 20-60% by mass, even more preferably 30-50% by mass, and particularly preferably 35-47% by mass.

As such a carrier (b), solid aluminoxanes are preferably used, and for example, the solid aluminoxanes disclosed in International Publication No. 2010/055652, International Publication No. 2013/146337, or International Publication No. 2014/123212 are particularly preferably used.

"Solid state" means that, under the reaction environment in which solid aluminoxane is used, the aluminoxane maintains a substantially solid state. More specifically, for example, when preparing an olefin polymerization solid catalyst component by contacting the various components constituting an olefin polymerization catalyst, it refers to the aluminoxane being in a solid state under specific temperature and pressure conditions in an inert hydrocarbon medium such as hexane or toluene used in the reaction.

The solid aluminoxane preferably contains an aluminoxane having at least one constituent unit selected from the constituent units represented by the following formula (4) and the constituent units represented by the following formula (5). More preferably, it contains an aluminoxane having the constituent units represented by the following formula (4), and even more preferably, it contains a polymethylaluminoxane consisting solely of the constituent units represented by the following formula (4).

In general formula (4), Me is a methyl group.
In general formula (5), ^R1 is a hydrocarbon group having 2 to 20 carbon atoms, preferably a hydrocarbon group having 2 to 15 carbon atoms, and more preferably a hydrocarbon group having 2 to 10 carbon atoms. Examples of hydrocarbon groups include alkyl groups, cycloalkyl groups, and aryl groups.

The structure of solid aluminoxanes is not always clearly understood. It is generally presumed to have a structure in which 2 to 50 repeating units represented by formula (4) and/or formula (5) are present, but this structure is not limited to this. Furthermore, the bonding configuration of these units can vary, for example, linear, cyclic, or clustered. Aluminoxanes are generally presumed to consist of one of these configurations or a mixture thereof. Aluminoxanes may also consist solely of the units represented by formula (4) or formula (5).

As the solid aluminoxane, solid polymethylaluminoxane is preferred, and solid polymethylaluminoxane consisting only of the constituent units represented by formula (4) is more preferred.
Solid aluminoxane functions as a catalyst support. Therefore, in addition to solid aluminoxane, it is not necessary to use other solid inorganic supports such as silica, alumina, silica-alumina, or magnesium chloride, or solid organic supports such as polystyrene beads, as catalyst supports.
Solid aluminoxanes can be prepared, for example, by the methods described in International Publication No. 2010/055652 and International Publication No. 2014/123212.

《Organic compound component (c)》
The metallocene catalyst may also optionally contain an organic compound component (c). The organic compound component (c) is used, if necessary, to improve polymerization performance and the physical properties of the resulting polymer. The aforementioned organoaluminum compound (b-1) may be used as the organic compound component (c). Other examples include alcohols, phenolic compounds, carboxylic acids, phosphorus compounds, amides, polyethers, and sulfonates.

Polymerization conditions
The polymerization of 4-methyl-1-pentene, which is contained in the 4-methyl-1-pentene polymer composition (X) according to the present invention, with ethylene and, if necessary, α-olefins having 3 to 20 carbon atoms, can be carried out by either liquid-phase polymerization methods such as dissolution polymerization or suspension polymerization, or by gas-phase polymerization methods. In liquid-phase polymerization, an inert hydrocarbon solvent can be used, specifically, aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as ethylene chloride, chlorobenzene, dichloromethane, trichloromethane, and tetrachloromethane; and a mixture of two or more solvents selected from these. Furthermore, the olefin containing 4-methyl-1-pentene itself can be used as the polymerization solvent.

In the polymerization described above, the method of use and the order of addition of each component can be chosen arbitrarily, but the following method is an example. Hereafter, the metallocene compound (a), the support (b), and the organic compound component (c) will also be referred to as "components (a) to (c)," respectively.
Method (i): A method of adding component (a) and component (b) to a polymerizer in any order.
Method (ii): A method of adding a catalyst component, in which component (a) is supported on component (b), to a polymerizer.

In each of the above methods (i) to (ii), component (c) may be added at any stage. Also, at least two of each catalyst component may be in contact with each other beforehand.
Furthermore, in the solid catalyst component in which component (a) is supported on component (b), olefins such as 4-methyl-1-pentene and 3-methyl-1-pentene may be prepolymerized, and further catalyst components may be supported on the prepolymerized solid catalyst component.

When polymerizing monomers such as 4-methyl-1-pentene using a metallocene catalyst, the amounts of each component that can constitute the metallocene catalyst used are as follows. Furthermore, the content of each component in the metallocene catalyst can be adjusted as follows.

Component (a) is used in an amount such that it is usually ^10⁻¹⁰ to ^10⁻² moles, preferably ^10⁻⁸ to ^10⁻³ moles per liter of reaction volume. Component (b-1) can be used in an amount such that the molar ratio [Al/M] of aluminum atoms in component (b-1) to all transition metal atoms (M) in component (a) is usually 10 to 10000, preferably 30 to 2000, and particularly preferably 150 to 500. Component (b-2) can be used in an amount such that the molar ratio [(b-2)/M] of component (b-2) to all transition metal atoms (M) in component (a) is usually 10 to 10000, preferably 30 to 2000, and even more preferably 150 to 500. Component (b-3) can be used in an amount such that the molar ratio [(b-3)/M] of component (b-3) to the total transition metal atoms (M) in component (a) is usually 10 to 10,000, preferably 30 to 2,000, and more preferably 150 to 500.

When using component (c), if component (b) is component (b-1), it can be used in an amount such that the molar ratio of aluminum atoms in component (b-1) to component (c) [Al/(c)] is usually 0.002 to 500, preferably 0.01 to 60. If component (b) is component (b-2), it can be used in an amount such that the molar ratio of component (b-2) to component (c) [(b-2)/(c)] is usually 0.002 to 500, preferably 0.01 to 60. If component (b) is component (b-3), it can be used in an amount such that the molar ratio of component (b-3) to component (c) [(b-3)/(c)] is usually 0.002 to 500, preferably 0.01 to 60.

The polymerization temperature is typically -50 to 200°C, preferably 0 to 100°C, and more preferably 20 to 100°C. The polymerization pressure is typically atmospheric pressure to 10 MPa gauge pressure, preferably atmospheric pressure to 5 MPa gauge pressure. The polymerization reaction can be carried out using batch, semi-continuous, or continuous methods. Hydrogen can be added to the polymerization system to control the molecular weight or polymerization activity of the resulting polymer; the appropriate amount of hydrogen added is approximately 0.001 to 100 NL per kg of olefin.

As for polymerization conditions, it is also possible to employ multi-stage polymerization, which involves two or more polymerization steps with different reaction conditions. For example, by carrying out stepwise polymerization under two different conditions with different amounts of hydrogen used, or different ratios of 4-methyl-1-pentene to ethylene and α-olefins with 3 to 20 carbon atoms (excluding 4-methyl-1-pentene), it is possible to obtain polymers with a desired molecular weight distribution or composition distribution.

The 4-methyl-1-pentene polymer according to the present invention can be produced by polymerizing or copolymerizing 4-methyl-1-pentene with a polymerizable monomer such as an α-olefin, if necessary, in the presence of a polymerization catalyst such as the metallocene catalyst described above.
When the 4-methyl-1-pentene polymer composition (X) according to the present invention is a mixed composition of two types of 4-methyl-1-pentene polymers, the first 4-methyl-1-pentene polymer and the second 4-methyl-1-pentene polymer may be produced separately and mixed in a desired ratio. Alternatively, it can be produced by a multi-stage polymerization method comprising, for example, a step (1) of producing the first 4-methyl-1-pentene polymer by slurry polymerization, and a step (2) of producing the second 4-methyl-1-pentene polymer by slurry polymerization in the presence of the polymer obtained in step (1) such that the amount of the second polymer is a desired mass% when the total amount of the first and second polymers is 100% by mass.

The multi-stage polymerization method described above comprises steps (1) and (2) with different polymerization conditions. However, it may also be a two-stage polymerization of steps (1) and (2), or a three-stage or higher polymerization method that includes additional steps in addition to steps (1) and (2).

《Process (1)》
In step (1), a first 4-methyl-1-pentene polymer is produced by slurry polymerization. In step (1), the ratio of 4-methyl-1-pentene to at least one monomer selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene), which is used as needed, is set so that the amounts of constituent units derived from each are in a desired ratio.

In step (1), a slurry containing the first 4-methyl-1-pentene polymer is obtained. The slurry concentration, i.e., the concentration of the first 4-methyl-1-pentene polymer particles, is usually 0.015 to 45% by mass, preferably 0.03 to 35% by mass.

《Process (2)》
In step (2), a second 4-methyl-1-pentene copolymer is produced by slurry polymerization in the presence of the first 4-methyl-1-pentene polymer obtained in step (1). In step (2), the supply ratio of 4-methyl-1-pentene to at least one monomer selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene), which is used as needed, is set so that the amounts of constituent units derived from each are in a desired ratio.

In step (2), a second 4-methyl-1-pentene polymer is produced such that, when the total amount of the first 4-methyl-1-pentene polymer obtained in step (1) and the second 4-methyl-1-pentene polymer obtained in step (2) is set to 100% by mass, the amount of the second 4-methyl-1-pentene polymer is the desired mass percentage.

In step (2), in one embodiment, 4-methyl-1-pentene and, if necessary, at least one monomer selected from the group consisting of ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) are added to a slurry containing the first 4-methyl-1-pentene polymer, and slurry polymerization of these monomers is carried out.

In step (2), a slurry containing particles of the first 4-methyl-1-pentene polymer and the second 4-methyl-1-pentene polymer is obtained. The slurry concentration, i.e., the particle concentration, is usually 3 to 50% by mass, preferably 5 to 40% by mass.

The above multi-stage polymerization method can employ slurry polymerization. "Slurry polymerization" refers to polymerization characterized in that the polymer produced by polymerization does not substantially dissolve in the medium used during polymerization, but rather exists in a dispersed form, for example, as fine particles, within the medium. The above multi-stage polymerization is not limited to slurry polymerization as long as the 4-methyl-1-pentene polymer composition (X) of the present invention can be obtained; it can also be carried out by solution polymerization or gas-phase polymerization, for example.

《Solid-liquid separation process》
The slurry containing 4-methyl-1-pentene polymer particles, which are obtained in step (2) and contain the first 4-methyl-1-pentene polymer and the second 4-methyl-1-pentene polymer, can be separated and recovered by solid-liquid separation, for example by filtration.

Post-processing steps
For 4-methyl-1-pentene polymer particles obtained by the above multi-stage polymerization method, for example, particles obtained in the above solid-liquid separation step, post-treatment steps such as known catalyst deactivation steps, catalyst residue removal steps, and drying steps may be performed as needed after production by the above method.
As described above, a mixture of the first 4-methyl-1-pentene polymer and the second 4-methyl-1-pentene polymer can be obtained.

Additives The polymer composition (X) of the present invention may contain conventionally known additives.
Examples of additives include secondary antioxidants, heat stabilizers, weather stabilizers, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes, fillers, and hydrochloric acid absorbents. The content of additives is not particularly limited, but is usually 0 to 50 parts by mass, preferably 0 to 10 parts by mass, per 100 parts by mass of the polymer component including copolymers (A) and (B), etc.
The 4-methyl-1-pentene polymer composition (X) of the present invention may contain one or more additives.

Characteristics of the 4-methyl-1-pentene polymer composition (X) The 4-methyl-1-pentene polymer composition (X) according to the present invention possesses the excellent physical properties of conventional 4-methyl-1-pentene polymers, such as heat resistance, transparency, lightness, mold release properties, and stain resistance, while having a longer semi-crystallization time and stretchability than conventional polymer compositions containing 4-methyl-1-pentene polymers. Therefore, a film containing the 4-methyl-1-pentene polymer composition (X) according to the present invention can have a homogeneous film thickness and excellent film thickness accuracy (thickness-to-thinness accuracy).

The 4-methyl-1-pentene polymer composition (X) according to the present invention comprises one or more 4-methyl-1-pentene polymers and satisfies the following requirements (X-1) to (X-4). Furthermore, it is preferable that the 4-methyl-1-pentene polymer composition (X) also satisfies one or more of the following requirements (X-5) to (X-7).

Requirement (X-1): Density measured in accordance with JIS K7112 (density gradient pipe method) is 0.82 to 0.88 g/ ^m³ .
The density is preferably 0.82 to 0.86 g/ ^m³ , and more preferably 0.82 to 0.84 g/ ^m³ .
By having the density of the 4-methyl-1-pentene polymer composition (X) within the aforementioned range, a lightweight film can be obtained.

Requirement (X-2): The melting point (Tm) measured by differential scanning calorimetry (DSC) is between 190°C and 250°C.
The melting point (Tm) is preferably in the range of 190°C to 245°C, more preferably 200°C to 240°C, even more preferably 200°C to 235°C, even more preferably 210°C to 235°C, and particularly preferably 220°C to 235°C.
The melting point (Tm) of the 4-methyl-1-pentene polymer composition (X) being within the aforementioned range provides heat resistance.

Requirement (X-3): Melting enthalpy ΔH is less than 35 J/g.
The enthalpy of fusion ΔH was measured using a 4-methyl-1-pentene polymer composition (X) in accordance with JIS K7122.
The enthalpy of melting ΔH is preferably 5 to 30 J/g, and more preferably 8 to 27 J/g.
The effect of improving the moldability into a film is obtained when the melting enthalpy ΔH of the 4-methyl-1-pentene polymer composition (X) is within the aforementioned range.

Requirement (X-4): The semi-crystallization time (Tc1/2) at 215°C, measured by DSC using the following method, is 220 seconds or longer, or is not measured.
Method for measuring semi-crystallization time (Tc1/2): Using a DSC8500 manufactured by PerkinElmer, the temperature is raised from 30°C to 280°C at a heating rate of 500°C/min, the temperature is maintained for 10 minutes, and then the temperature is lowered to 215°C at a cooling rate of 500°C/min. The semi-crystallization time at 215°C is then measured.
The semi-crystallization time is preferably 230 seconds or longer, or not measured; more preferably 240 seconds or longer, or not measured; even more preferably 300 seconds or longer, or not measured; even more preferably 400 seconds or longer, or not measured; and particularly preferably 500 seconds or longer, or not measured.
When the semi-crystallization time of the 4-methyl-1-pentene polymer composition (X) satisfies the above conditions, the crystallization rate during melt molding is slowed, the stretchability is improved, and the moldability into a film is excellent.

Requirement (X-5): The content of constituent units derived from 4-methyl-1-pentene is 90.0 mol% or more and less than 100 mol%, and the content of constituent units derived from ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is greater than 0 mol% and 10.0 mol% or less.
The content of constituent units derived from 4-methyl-1-pentene is preferably 91.0 to 99.5 mol%, more preferably 92.0 to 99.0 mol%. The content of constituent units derived from ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is preferably 0.5 to 9.0 mol%, more preferably 1.0 to 8.0 mol%.
By ensuring that the content of the constituent units of the 4-methyl-1-pentene polymer composition (X) satisfies the above conditions, the film can be made to have excellent heat resistance, transparency, and release properties.

Requirement (X-6): The intrinsic viscosity [η] measured in decalin at 135°C is 1.5 to 8.0 dl/g. Specifically, it can be measured, for example, by the measurement method described in the examples below.
The intrinsic viscosity [η] is preferably 1.6 to 7.0 dL/g, more preferably 1.7 to 6.0 dL/g, even more preferably 1.8 to 5.0 dL/g, even more preferably 1.9 to 4.5 dL/g, and particularly preferably 2.0 to 4.0 dL/g.
The 4-methyl-1-pentene polymer composition (X) has an intrinsic viscosity that satisfies the above range, allowing it to form films by stretching methods, and is particularly suitable for inflation molding.

Requirement (X-7): The melt tension (MT) measured at 260°C is 25 mN or greater.
The melt tension is preferably 26 mN or more, more preferably 26 to 100 mN, and even more preferably 26.5 to 50 mN. The melt tension can be adjusted, for example, by controlling the molecular weight of the polymer.
The 4-methyl-1-pentene polymer composition (X) has a relatively high melt tension that satisfies the above range, allowing it to form a film by a stretching method, and is particularly suitable for inflation molding.

<Film and method for manufacturing the same>
The film of the present invention comprises the above-described 4-methyl-1-pentene polymer composition (X). Preferably, the film of the present invention is made of the above-described 4-methyl-1-pentene polymer composition (X) and is obtained by molding the above-described 4-methyl-1-pentene polymer composition (X).

The film of the present invention is not particularly limited, but its average film thickness is typically 0.1 to 1000 μm, preferably 0.1 to 100 μm, more preferably 1.0 to 300 μm, and even more preferably 5 to 200 μm.

The film of the present invention can exhibit minimal variation in film thickness and excellent accuracy. Preferably, the film of the present invention has a thickness accuracy of less than 25, more preferably 23 or less, and even more preferably 20 or less, calculated as 2σ ÷ a × 100 (%) from the average value (a) of film thickness obtained by measuring at a sufficient number of measurement points and the standard deviation (σ) of the variation in film thickness. The average value (a) and standard deviation (σ) of film thickness depend on the size of the film, etc., but can be determined, for example, from values obtained by measuring the thickness at 50 equally spaced points, as shown in the examples described later.

The film of the present invention may contain the above-described 4-methyl-1-pentene polymer composition (X), and can be manufactured by conventionally known film molding methods such as casting, extrusion, uniaxial stretching, biaxial stretching, and inflation molding. However, because the 4-methyl-1-pentene polymer composition (X) has excellent stretchability, it can be suitably manufactured by inflation molding, which provides excellent bubble stability during inflation molding and allows for stable molding. When the film of the present invention is an inflation film manufactured by inflation molding, it is easy to produce a film with a small film thickness, and moreover, it is preferable because it has little variation in film thickness and excellent film thickness accuracy. Furthermore, inflation molding is preferable because it is easy to obtain a film with uniform film thickness throughout, there is no need to remove non-uniform parts, and it is excellent in terms of yield during manufacturing.
Furthermore, the film of the present invention also exhibits excellent release properties due to the inclusion of a 4-methyl-1-pentene polymer composition (X).

Inflation Film and Inflation Molding : The film of the present invention is preferably an inflation film obtained by inflation molding.
The inflation film according to the present invention can be produced by inflation molding the above-described 4-methyl-1-pentene polymer composition (X).

Inflation molding can be carried out using conventionally known inflation molding methods capable of forming films. For example, the inflation film of the present invention can be produced by inflation molding the above-described 4-methyl-1-pentene polymer composition (X) using an inflation film molding machine. Air-cooled inflation molding is preferably employed in this process.

The conditions for inflation molding are not particularly limited, but the molding temperature is preferably above the melting point of the raw material resin used and below 300°C. Furthermore, the expansion ratio (bubble ratio) during inflation molding refers to the ratio of the maximum bubble diameter to the die diameter, and is preferably greater than 1.0, more preferably between 1.1 and 5.0, even more preferably between 1.2 and 4.5, even more preferably between 1.5 and 4.0, and particularly preferably between 1.8 and 3.0. The take-up speed is determined by the film thickness and width and the extrusion amount, and can be adjusted within a range that maintains film formation stability, but is generally preferably between 1 and 150 m/min, and more preferably between 1 and 100 m/min.

The inflation film of the present invention can be suitably used as a material for, for example, daily necessities packaging, food packaging, food containers, retort containers, protective films, cosmetic films/sheets, shrink films, infusion bags, heat-sealable films, medical containers, release films, and the like.

The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.
In the following, each physical property was measured or evaluated using the following methods.

<Content of constituent units derived from ethylene or α-olefins (excluding 4-methyl-1-pentene)>
The content of structural units derived from 4-methyl-1-pentene, and the content of ethylene or α-olefin (excluding 4-methyl-1-pentene) in the polymer composition (or each polymer) were calculated from the results of measurements by ^13C -NMR using the following apparatus and conditions.

Using a JEOL Ltd. ECP500 nuclear magnetic resonance spectrometer, the following measurements were taken: orthodichlorobenzene/deuterated benzene (80/20 vol%) mixed solvent, sample concentration 55 mg/0.6 mL, measurement temperature 120°C, observed nucleus ^13C (125 MHz), sequence single-pulse proton decoupling, pulse width 4.7 μs (45° pulse), repetition time 5.5 seconds, cumulative count over 10,000 times, and chemical shift reference value of 27.50 ppm. The content of constituent units derived from ⁴ -methyl-1-pentene and constituent units derived from ethylene or α-olefins (excluding 4-methyl-1-pentene) was quantified from the obtained 13C-NMR spectrum.

<Intrinsic viscosity [η]>
The intrinsic viscosity [η] of polymers or polymer compositions was measured at 135°C using decalin solvent. Specifically, approximately 20 mg of polymerization powder, pellets, or resin mass was dissolved in 15 mL of decalin, and the specific viscosity ηsp was measured in an oil bath at 135°C. After diluting this decalin solution by adding 5 mL of decalin solvent, the specific viscosity ηsp was measured again in the same manner. This dilution procedure was repeated two more times, and the value of ηsp/C when the concentration (C) was extrapolated to 0 was determined as the intrinsic viscosity (see formula below).
[η]=lim(ηsp/C) (C→0)

<Density>
The density was measured in accordance with JIS K7112 (density gradient pipe method).

<Melting point (Tm) and enthalpy of melting (ΔH)>
Using a DSC measuring device (DSC220C) manufactured by Seiko Instruments Inc., the exothermic and endothermic curves were determined, and the temperature at the melting peak position during heating was defined as the melting point (Tm). The area of the melting peak at the aforementioned melting peak was defined as the enthalpy of fusion (ΔH).
Calorimetry was performed as follows: Approximately 5 mg of the sample was cut from a 0.5 mm thick injection-molded test piece, placed in an aluminum pan for measurement, and heated from 20°C to 280°C at a heating rate of 10°C/min. After holding at 280°C for 5 minutes, the temperature was lowered to 20°C at a cooling rate of 10°C/min, held at 20°C for 5 minutes, and then heated again from 20°C to 280°C at a heating rate of 10°C/min, and lowered again to 50°C at a cooling rate of 50°C/min. The melting peak that appeared during the second heating was defined as the melting point (Tm).
If there are multiple melting peaks, the value with the higher peak temperature is defined as the melting point (Tm), and the peak area at the higher melting point is defined as the enthalpy of fusion (ΔH).

<Semi-crystallization time (Tc1/2)>
Using a DSC measuring device (DSC8500) manufactured by PerkinElmer Co., Ltd., the exothermic and endothermic curves were determined, and the time at which the peak area at 215°C was halved was defined as the semi-crystallization time (Tc1/2). The measurement was performed as follows: Approximately 5 mg of the sample was cut from a 0.5 mm thick injection-molded test piece, placed in an aluminum pan for measurement, heated from 30°C to 280°C at a heating rate of 500°C/min, held at 280°C for 10 minutes, and then cooled to 215°C at a cooling rate of 500°C/min for measurement.

<Melt Tension>
A Capillograph 1D device manufactured by Toyo Seiki Seisakusho was used. The sample was placed in a melting furnace (diameter 9.55 mm) set to 260°C and allowed to melt completely. Then, at an extrusion speed of 15 mm/min, the molten resin was passed through a capillary with an L/D ratio of 8/2.095 mm and an inlet angle of 180°. The molten resin was then passed through a pulley fixed 58 cm from the bottom of the capillary, and the stress on the pulley was measured when the molten resin was wound up at a speed of 15 m/min. This stress was defined as the melt tension.

<Bubble Stability>
The stability of bubbles in inflation molding was evaluated according to the following criteria.
◎: The bubbles remained stable for a long period of time, resulting in a good film.
○: Although slight movement occurred in the bubbles, stable molding was possible.
×: The bubbles fluctuated up and down, causing variations in film width, or the molding process failed.

<Film thickness, thickness accuracy>
The thickness was measured at 1 cm intervals using a thickness measuring dial gauge at 50 points, and the average value was calculated. Furthermore, the thickness accuracy was determined by dividing twice the standard deviation (σ) of the variation (2σ) by the above average value and expressing it as a percentage (×100).
Values less than 25 were marked with ○, and values 25 or greater were marked with ×.

<Surface tension>
In accordance with JIS K6768, several drops of the wetting reagent mixture were dropped onto the film, and the test mixture was immediately spread using a cotton swab. After 2 seconds, if the center of the liquid film remained in its original state without tearing, it was determined to be "wet," and if tearing occurred, it was determined to be "not wet." The surface tension (mN/m) was recorded when the mixture composition changed from one that was not wet to one that was determined to wet the film.
Surface tension is an indicator of mold release properties.

[Polymerization examples A-1 to A-4]
Following the polymerization method described in Comparative Example 1 ([0158]) of International Publication 2017/150265, the α-olefin was replaced with the α-olefin listed in Table 1, and the proportions of 4-methyl-1-pentene, α-olefin, and hydrogen were changed so that the physical properties of the resulting copolymer would be as shown in Table 1, thereby obtaining 4-methyl-1-pentene copolymers A-1 to A-4.

[Polymerization examples A-5, A-6]
By changing the proportions of 4-methyl-1-pentene, other α-olefins (a mass mixture of 1-hexadecene, 1-octadecene, etc.), and hydrogen, according to the polymerization method described in Comparative Example 9 of International Publication No. 2006/054613, 4-methyl-1-pentene polymers A-5 and A-6, as shown in Table 1, were obtained.

[Polymerization examples B-1, B-2]
Following the polymerization method described in Production Example 1 ([0182] to [0185]) of Japanese Patent Publication No. 2018-162408, α-olefins were replaced with α-olefins listed in Table 1, and the proportions of 4-methyl-1-pentene, α-olefin, and hydrogen used were changed so that the physical properties of the resulting copolymers matched the values in Table 1, thereby obtaining 4-methyl-1-pentene copolymers B-1 and B-2.

[Example 1]
Manufacturing of polymer compositions
To 70 parts by mass of polymer A-1 and 30 parts by mass of polymer B-1 obtained above, 0.5 parts by mass of n-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate was added as a heat-resistant stabilizer. The resulting mixture was then granulated using a twin-screw extruder BT-30 (screw system 30 mmφ, L/D = 46) manufactured by Plastics Engineering Laboratory Co., Ltd., under the conditions of a set temperature of 270°C, a resin extrusion rate of 60 g/min, and 200 rpm to obtain polymer composition pellets. The physical properties are shown in Table 2.

Using the pellets obtained from the production of the inflation film , a film was formed using a 20 mmφ inflation molding machine (ring die diameter 30 mmφ, lip opening 0.7 mmφ). The molding conditions were adjusted so that the extruder temperature was 285°C, the die temperature was 260°C, the take-up speed was 7 m/min, and the bubble diameter was 60 mmφ relative to the ring die diameter, i.e., the expansion ratio (bubble ratio) was 2.0. Film formation was carried out in the upward blowing direction with air cooling, aiming for a film thickness of 20 μm. The bubbles remained stable for a long time, and a good film was obtained. The physical properties of the obtained film were evaluated. The results are shown in Table 2.

[Example 2]
In Example 1, granulation and film formation were carried out in the same manner as in Example 1, except that the 4-methyl-1-pentene polymer used was changed to 32 parts by mass of polymer A-2 and 68 parts by mass of polymer B-2 obtained above. Although slight movement occurred in the bubbles, stable molding was possible. The physical properties of the obtained film were evaluated. The results are shown in Table 2.

[Example 3]
In Example 1, granulation and film formation were carried out in the same manner as in Example 1, except that the 4-methyl-1-pentene polymer used was replaced with 100 parts by mass of polymer A-3 obtained above. The bubbles remained stable for a long time, and a good film was obtained. The physical properties of the obtained film were evaluated. The results are shown in Table 2.

[Example 4]
In Example 1, granulation and film formation were carried out in the same manner as in Example 1, except that the 4-methyl-1-pentene polymer used was replaced with 100 parts by mass of polymer A-4 obtained above. The bubbles remained stable for a long time, and a good film was obtained. The physical properties of the obtained film were evaluated. The results are shown in Table 2.

[Comparative Example 1]
In Example 1, granulation and film formation were carried out in the same manner as in Example 1, except that the 4-methyl-1-pentene polymer used was replaced with 100 parts by mass of polymer A-5 obtained above. Bubbles fluctuated up and down, causing fluctuations in film width. The physical properties of the obtained film were evaluated. The results are shown in Table 2.

[Comparative Example 2]
Granulation and film formation were carried out in the same manner as in Example 1, except that the 4-methyl-1-pentene polymer used was replaced with 100 parts by mass of polymer A-6 obtained in the above production example. When attempting to expand the mixture to a bubble ratio of 2.0, the bubbles became meandering and film formation was not possible.

[Reference example 1]
In Comparative Example 2, granulation and film formation were performed in the same manner as in Comparative Example 2, except that the film was formed without expanding the bubbles, i.e., without stretching and expansion (air inflation) with a bubble ratio of 1.0. When the discharge rate was reduced to aim for a film thickness of 20 μm, the bubbles fluctuated up and down, resulting in fluctuations in the film width. When the discharge rate was adjusted to aim for a film thickness of 40 μm, the bubbles remained stable for a long time, and a good film was obtained. The physical properties of the obtained film were evaluated. The results are shown in Table 2.

As shown in Table 2 above, in Examples 1 to 4, which used a 4-methyl-1-pentene polymer composition that satisfies all requirements (X-1) to (X-4) of the present invention, it was found that inflation film molding with stretching could be performed stably, and the resulting film exhibited excellent thickness-to-thickness accuracy.

On the other hand, in Comparative Example 1, which used a 4-methyl-1-pentene polymer composition that did not satisfy requirement (X-4) of the present invention, and in Comparative Example 2, which used a 4-methyl-1-pentene polymer composition that did not satisfy requirements (X-3) and (X-4) of the present invention, it was found that the bubbles were unstable and a stable film could not be produced.

Furthermore, from Comparative Example 2 and Reference Example 1, it was found that when a 4-methyl-1-pentene polymer composition that does not satisfy requirements (X-3) and (X-4) of the present invention, has a high melting enthalpy ΔH, and a short semi-crystallization time, is used, while film molding without stretching (film molding with a bubble ratio of 1.0) is possible (see Reference Example 1), it is not suitable for film molding involving stretching and expansion (see Comparative Example 2). Therefore, the objective of the present invention, which is to provide a method for manufacturing a film by inflation film molding involving stretching, cannot be achieved.

Claims (9)

A film characterized by containing a 4-methyl-1-pentene polymer composition (X) that satisfies the following requirements (X-1) to (X-4).
Requirement (X-1): Density measured in accordance with JIS K7112 (density gradient pipe method) is 0.82 to 0.88 g/ ^m³ .
Requirement (X-2): The melting point (Tm) measured by differential scanning calorimetry (DSC) is between 190°C and 250°C.
Requirement (X-3): Melting enthalpy ΔH is less than 35 J/g.
Requirement (X-4): The semi-crystallization time at 215°C, measured by DSC using the following measurement method, is 220 seconds or longer, or is not measured.
Method for measuring semi-crystallization time: Using a PerkinElmer DSC8500, the temperature is raised from 30°C to 280°C at a heating rate of 500°C/min, the temperature is maintained for 10 minutes, and then the temperature is lowered to 215°C at a cooling rate of 500°C/min. The semi-crystallization time at 215°C is then measured. The film according to claim 1, wherein the 4-methyl-1-pentene polymer composition (X) satisfies the following requirements (X-5) and (X-6).
Requirement (X-5): The content of constituent units derived from 4-methyl-1-pentene is 90.0 mol% or more and less than 100 mol%, and the content of constituent units derived from ethylene and α-olefins having 3 to 20 carbon atoms (excluding 4-methyl-1-pentene) is greater than 0 mol% and 10.0 mol% or less.
Requirement (X-6): The intrinsic viscosity [η] measured in decalin at 135°C is 1.5 to 8.0 dl/g. The film according to claim 1 or 2, wherein the 4-methyl-1-pentene polymer composition (X) satisfies the following requirement (X-7).
Requirement (X-7): The melt tension (MT) measured at 260°C is 25 mN or greater. A film according to any one of claims 1 to 3, having an average thickness of 0.1 to 100 μm. An inflation film, as described in any one of claims 1 to 4. A film for packaging purposes, as described in any one of claims 1 to 5. A method for producing a film, characterized by comprising a step of inflation molding a 4-methyl-1-pentene polymer composition (X) that satisfies the following requirements (X-1) to (X-4).
Requirement (X-1): Density measured in accordance with JIS K7112 (density gradient pipe method) is 0.82 to 0.88 g/ ^m³ .
Requirement (X-2): The melting point (Tm) measured by differential scanning calorimetry (DSC) is between 190°C and 250°C.
Requirement (X-3): Melting enthalpy ΔH is less than 35 J/g.
Requirement (X-4): The semi-crystallization time at 215°C, measured by DSC using the following measurement method, is 220 seconds or longer, or is not measured.
Method for measuring semi-crystallization time: Using a PerkinElmer DSC8500, the temperature is raised from 30°C to 280°C at a heating rate of 500°C/min, the temperature is maintained for 10 minutes, and then the temperature is lowered to 215°C at a cooling rate of 500°C/min. The semi-crystallization time at 215°C is then measured. A method for manufacturing a film according to claim 7, wherein the expansion ratio (bubble ratio) during inflation molding exceeds 1.0. A method for manufacturing a film according to claim 7 or 8, comprising manufacturing the film according to any one of claims 1 to 6.