Method for producing film

Abstract

The present invention relates to a method for manufacturing a film, and more particularly, to a method for manufacturing a film, which comprises molding a film by extruding a composition containing a liquid crystal polyester from a die under the following conditions:-10 < = FT-set temperature (DEG C) of the die < = 30, FT: flow initiation temperature (DEG C) of the liquid crystal polyester, and the molding may be molding by an inflation method or a T-die method.

Description

Technical Field

[0001] The present disclosure relates to methods of making films.

[0002] This application claims priority based on Japanese Patent Application No. 2022-092148 filed in Japan on June 7, 2022, and the contents are incorporated herein by reference. Background Art

[0003] As a method for producing a film containing a liquid crystal polyester, a T-die method, an inflation method, and the like are known.

[0004] For example, Patent Document 1 describes that during film formation, the polymer flow path of a film forming apparatus is controlled at a temperature of the melting point of a liquid crystalline resin composition + 10° C. over the entire portion of a T-die.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2006-299254 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, according to the method for producing a film containing a liquid crystal polyester, there is still room for research on improving the surface smoothness of the produced film.

[0010] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a method for producing a film containing a liquid crystal polyester and having excellent surface smoothness.

[0011] Means for solving problems

[0012] The present disclosure has the following aspects.

[0013] (1) A method for producing a film, comprising: extruding a composition containing a liquid crystal polyester from a die under the following conditions to form a film.

[0014] -10≤FT-The set temperature of the above die (℃)≤30

[0015] FT: Flow starting temperature of the above liquid crystal polyester (°C)

[0016] (2) The method for producing a film according to (1) above, wherein the set temperature of the die further satisfies the following conditions.

[0017] -35≤Tr-The set temperature of the above die (℃)≤10

[0018] Tr: The viscosity of the above composition measured under the following measurement conditions is 1.0×10 4 Temperature in Pa·s (℃)

[0019] Determination conditions:

[0020] Device: Rotational rheometer

[0021] Cooling speed: 5℃ / min

[0022] Strain: 0.05%

[0023] Frequency: 1Hz

[0024] (3) The method for producing a film according to (1) or (2) above, wherein the liquid crystal polyester contains a liquid crystal polyester (A) having a repeating unit represented by the following formula (A1).

[0025] (A1)-O-Ar a1 -CO-

[0026] (Ar a1 represents a phenylene group, a naphthylene group or a biphenylene group,

[0027] Ar a1 The hydrogen atoms in the above groups represented may also be independently substituted by halogen atoms, alkyl groups or aryl groups.

[0028] (4) The method for producing a film according to (3) above, wherein the number of the repeating units represented by the formula (A1) exceeds 40% of the total number (100%) of all repeating units constituting the liquid crystal polyester (A).

[0029] (5) The method for producing a film according to (3) or (4) above, wherein the liquid crystal polyester (A) consists only of a repeating unit represented by the formula (A1).

[0030] (6) The method for producing a film according to any one of (3) to (5) above, wherein the liquid crystal polyester (A) contains a repeating unit represented by the following formula (A1-1).

[0031] (A1-1)-O-Ar a1-1 -CO-

[0032] (Ar a1-1 represents naphthylene,

[0033] Ar a1-1 The hydrogen atoms in the above groups represented may also be independently substituted by halogen atoms, alkyl groups or aryl groups.

[0034] (7) A method for producing a film according to (6) above, wherein the number of repeating units represented by the above formula (A1-1) is greater than 40% and less than 90% relative to the total number (100%) of repeating units conforming to the above formula (A1).

[0035] (8) The method for producing a film according to any one of (1) to (7) above, wherein the molding is performed by an inflation method or a T-die method.

[0036] (9) A film comprising a liquid crystal polyester (A) comprising a repeating unit represented by the following formula (A1): (A1)-O-Ar a1 -CO-

[0037] (Ar a1 represents a phenylene group, a naphthylene group or a biphenylene group,

[0038] Ar a1 The hydrogen atoms in the above groups represented may also be independently substituted by halogen atoms, alkyl groups or aryl groups.

[0039] The surface roughness (Ra) of the film is 1.0 μm or less.

[0040] Effects of the Invention

[0041] A method for producing a film containing a liquid crystal polyester and capable of producing a film having excellent surface smoothness can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram showing an example of the configuration of a production apparatus used in a film production method according to an embodiment of the present disclosure and an example of a film production process.

[0043] Figure 2 yes Figure 1 An enlarged view of a portion of the die of the manufacturing apparatus. DETAILED DESCRIPTION

[0044] Hereinafter, the method for producing a film and embodiments of the film disclosed herein will be described. The film of the embodiment contains a liquid crystal polyester.

[0045] 《Method for producing membrane》

[0046] The method for producing a film according to the embodiment includes extruding a composition including a liquid crystal polyester from a die under the following conditions to form a film.

[0047] -10≤FT-Die setting temperature (℃)≤30

[0048] In this specification, FT represents the flow starting temperature (° C.) of the liquid crystal polyester.

[0049] Examples of the molding include molding by an inflation method and a T-die method, and molding by an inflation method is preferred.

[0050] Hereinafter, the method for producing a film according to the embodiment will be described by taking as an example a case where a film is produced by an inflation method.

[0051] Figure 1 This is a schematic diagram showing an example of the configuration of a production apparatus 10 used in a film production method according to an embodiment using an inflation method and an example of a film production process.

[0052] First, a composition containing a liquid crystal polyester is put into the barrel 111 of the extruder 11, and heated while the screw 112 is rotated to obtain a fluid body M of the composition.

[0053] Next, the fluid M is extruded from the die 12, and air is introduced into the inside to expand the fluid M, thereby obtaining a cylindrical tubular film 2. A guide plate 14 is provided in the feeding direction of the tubular film 2, and the guide plate 14 guides the tubular film 2 to the nip roller 16. When the tubular film 2 is sandwiched by the nip roller 16, the air inside the tube of the tubular film 2 is removed, thereby obtaining a film 1. The film 1 is wound by a winder 18.

[0054] Figure 2 It is an enlarged view of a portion of the die 12 of the above-mentioned production apparatus 10. The die 12 includes a die lower portion 121, a die middle portion 122, and a die upper portion 123. The set temperature of each portion of the die can be set independently.

[0055] Like this, when the die is divided into a plurality of parts, etc. and each part can set the temperature independently, the setting temperature of each part of the die is preferably the same temperature as each other. The setting temperature of each part of the die can also be a temperature different from each other. When the setting temperature of each part of the die is different from each other, the setting temperature of the die in this specification refers to the setting temperature of the die of the part with the ejection outlet of the composition. In the die 12, the setting temperature of the die is the setting temperature of the die top 123.

[0056] In addition, when the die is not divided into a plurality of parts, or when the temperature of each part cannot be set independently, the set temperature of the entire die is the set temperature of the die.

[0057] In the film manufacturing method of the embodiment, the condition of -10≤FT-die setting temperature (° C.)≤30 is satisfied, and preferably the condition of -10≤FT-die setting temperature (° C.)≤15 is satisfied.

[0058] When the setting temperature (° C.) of the FT-die is -10 or higher, a film having excellent surface smoothness can be produced.

[0059] When the set temperature (° C.) of the FT-die is 30 or less, the liquid crystal polyester can be discharged well from the die.

[0060] It is preferable to satisfy the condition of -35≤Tr-die setting temperature (° C.)≤10, and it is more preferable to satisfy the condition of -35≤Tr-die setting temperature (° C.)≤-5.

[0061] In this specification, Tr represents the viscosity of the above composition measured under the following measurement conditions: 1.0×10 4 Temperature (°C) in Pa·s.

[0062] Determination conditions:

[0063] Device: Rotational rheometer

[0064] Cooling speed: 5℃ / min

[0065] Strain: 0.05%

[0066] Frequency: 1Hz

[0067] By setting the set temperature (° C.) of the Tr-die to -35 or higher, a film having more excellent surface smoothness can be produced.

[0068] By setting the set temperature (° C.) of the Tr-die to 10 or less, the discharge of the composition from the die becomes more favorable.

[0069] In the above, refer to Figures 1-2 The setting temperature of the die has been described by taking the die used in the inflation method as an example, but the setting temperature described above can be similarly applied to a die used in any molding method such as the T-die method.

[0070] The thickness of the film manufactured by the film manufacturing method of the embodiment may be, for example, 30 μm to 300 μm, 30 μm to 200 μm, or 50 μm to 200 μm.

[0071] The film thickness is set as the average value of values ​​measured at 9 or more locations 5 mm or more inside the outer periphery of the film. More specifically, it can be measured using a U-shaped steel plate micrometer (eg, PMU150-25MJ (Mitutoyo Corporation)).

[0072] The value of the surface roughness (Ra) of the film manufactured by the manufacturing method of the film of the embodiment is preferably 1.0 μm or less, more preferably 0.7 μm or less. The value of the surface roughness (Ra) can be 0.2 μm or more and 0.7 μm or less. The value of the surface roughness (Ra) can be 0.2 μm or more and 0.7 μm or less, 0.2 μm or more and 0.6 μm or less, 0.2 μm or more and 0.5 μm or less. The value of the surface roughness (Ra) can be 0.3 μm or more and 0.7 μm or less, 0.3 μm or more and 0.6 μm or less, 0.3 μm or more and 0.5 μm or less.

[0073] The surface roughness (Ra) of the film is set to a value obtained by measuring the arithmetic mean roughness (Ra) in the film width direction using a surface roughness meter (for example, SE600LK31 (manufactured by Kosaka Laboratory Co., Ltd.)) under the following conditions.

[0074] Stylus tip radius: 2μm

[0075] Stylus speed: 0.5mm / sec

[0076] Measuring force: 0.75mN

[0077] Measuring length: 4mm

[0078] Cut-off value: 0.8mm

[0079] (Liquid Crystal Polyester)

[0080] The composition used in the method for producing a film according to the present embodiment contains a liquid crystal polyester.

[0081] That is, the film produced by the method for producing a film according to the embodiment contains a liquid crystal polyester.

[0082] The liquid crystal polyester is a polyester that exhibits liquid crystallinity in a molten state, and is preferably a polyester that melts at a temperature of 450° C. or lower.

[0083] The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester using only aromatic compounds as raw material monomers.

[0084] Hereinafter, the liquid crystal polyester (A) preferably used in the method for producing the film of the present embodiment will be described.

[0085] The liquid crystal polyester preferably includes a liquid crystal polyester (A) including a repeating unit represented by the following formula (A1).

[0086] The liquid crystal polyester may contain 50% by mass or more of the liquid crystal polyester (A), or 80% by mass or more, based on the total mass of the liquid crystal polyester, or may consist of the liquid crystal polyester (A) alone.

[0087] The liquid crystal polyester (A) includes a repeating unit represented by the following formula (A1).

[0088] (A1)-O-Ar a1 -CO-

[0089] (Ar a1 represents a phenylene group, a naphthylene group or a biphenylene group,

[0090] Ar a1 The hydrogen atoms in the above groups represented may also be independently substituted by halogen atoms, alkyl groups or aryl groups.

[0091] As the above Ar a1 The phenylene group in the above-mentioned Ar is preferably 1,4-phenylene. a1 The naphthylene in the formula (A) is preferably 2,6-naphthylene. a1 The biphenylene group is preferably 4,4'-biphenylene.

[0092] Ar a1 It is more preferred that the hydrogen atoms in the above-mentioned groups represented are each independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0093] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0094] Examples of the alkyl group having 1 to 10 carbon atoms which may replace a hydrogen atom include methyl, ethyl, 1-propyl, isopropyl, 1-butyl, isobutyl, sec-butyl, tert-butyl, 1-hexyl, 2-ethylhexyl, 1-octyl and 1-decyl.

[0095] Examples of the aryl group having 6 to 20 carbon atoms which may replace a hydrogen atom include monocyclic aromatic groups such as phenyl, o-tolyl, m-tolyl, p-tolyl, and the like, and condensed aromatic groups such as 1-naphthyl, 2-naphthyl, and the like.

[0096] In Ar a1 When one or more hydrogen atoms in the above-mentioned group represented by is substituted with the above-mentioned halogen atom, the above-mentioned alkyl group or the above-mentioned aryl group, the number of the groups replacing the above-mentioned hydrogen atoms is preferably 1 or 2, and more preferably 1.

[0097] The repeating unit represented by the above formula (A1) is a repeating unit derived from an aromatic hydroxycarboxylic acid.

[0098] Examples of the aromatic hydroxycarboxylic acid include p-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-3-naphthoic acid, 1-hydroxy-5-naphthoic acid, 4-hydroxy-4'-carboxy diphenyl ether, or aromatic hydroxycarboxylic acids in which a portion of hydrogen atoms on the aromatic ring of these aromatic hydroxycarboxylic acids are substituted with a substituent selected from the group consisting of an alkyl group, an aryl group, and a halogen atom. The aromatic hydroxycarboxylic acid can be used alone or in combination of two or more in the manufacture of the liquid crystal polyester. As the repeating unit represented by the above formula (A1), Ar is preferably a1 is a repeating unit of 1,4-phenylene (for example, a repeating unit derived from 4-hydroxybenzoic acid) and Ar a1 The repeating unit is a 2,6-naphthylene group (for example, a repeating unit derived from 2-hydroxy-6-naphthoic acid).

[0099] In this specification, "origin" means that the chemical structure changes due to polymerization of raw material monomers, and no other structural changes occur.

[0100] The source here also includes the case where the source is a polymerizable derivative of the compound. For example, each repeating unit may be a repeating unit derived from an acylate of an aromatic hydroxycarboxylic acid.

[0101] In the liquid crystal polyester (A), as the content ratio of the repeating unit represented by the formula (A1) increases, the viscosity increase during the process of film stretching and composition cooling can be suppressed, and a film having excellent surface smoothness can be easily obtained.

[0102] Relative to the total number (100%) of all repeating units constituting the above-mentioned liquid crystal polyester (A), the number of repeating units represented by the above-mentioned formula (A1) may be greater than 40%, greater than 50%, greater than 50%, greater than 60%, greater than 60%, greater than 70%, greater than 70%, greater than 80%, greater than 80%, greater than 85%, greater than 85%, greater than 90%, greater than 90%, greater than 95%, greater than 95%, or greater than 98%, and may be composed only of repeating units represented by the above-mentioned formula (A1) (that is, the number of repeating units represented by the above-mentioned formula (A1) may be 100%).

[0103] As the liquid crystal polyester (A) listed above,

[0104] It is preferred that the repeating unit represented by the above formula (A1) contains a repeating unit represented by the following formula (A1-1).

[0105] (A1-1)-O-Ar a1-1 -CO-

[0106] (Ar a1-1 represents naphthylene,

[0107] Ar a1-1 The hydrogen atoms in the above groups represented may also be independently substituted by halogen atoms, alkyl groups or aryl groups.

[0108] The number of repeating units represented by the above formula (A1-1) is preferably greater than 40% and less than 90%, more preferably greater than 65% and less than 80%, and further preferably greater than 70% and less than 75%, relative to the total number (100%) of repeating units conforming to the above formula (A1).

[0109] In the liquid crystal polyester (A), if the content ratio of the repeating unit represented by the above formula (A1-1) is within the above numerical range, the viscosity increase caused by the temperature drop during the process of stretching the film and cooling the composition can be appropriately suppressed, so that a film with excellent surface smoothness can be easily obtained.

[0110] As the liquid crystal polyester (A) listed above, the repeating unit represented by the above formula (A1) preferably includes a repeating unit represented by the following formula (A1-1) and a repeating unit represented by the following formula (A1-2), and it is more preferably composed only of a repeating unit represented by the following formula (A1-1) and a repeating unit represented by the following formula (A1-2).

[0111] (A1-1)-O-Ar a1-1 -CO-

[0112] (A1-2)-O-Ar a1-2 -CO-

[0113] (Ar a1-1 represents naphthylene,

[0114] Ar a1-2 represents a phenylene group.

[0115] Ar a1-1 or Ar a1-2 The hydrogen atoms in the above groups represented may also be independently substituted by halogen atoms, alkyl groups or aryl groups.

[0116] As the above Ar a1-1 The naphthylene in the formula (A) is preferably 2,6-naphthylene. a1-2 The phenylene group is preferably 1,4-phenylene.

[0117] As Ar a1-1 and Ar a1-2 The halogen atom, alkyl group or aryl group in the a1 The groups exemplified in .

[0118] As the liquid crystal polyester (A) listed above, it is preferred that: it is composed only of repeating units represented by the above formula (A1), and the repeating units represented by the above formula (A1) include repeating units represented by the following formula (A1-3) and repeating units represented by the following formula (A1-4), and it is more preferred that: it is composed only of repeating units represented by the following formula (A1-3) and repeating units represented by the following formula (A1-4).

[0119] (A1-3)-O-Ar a1-3 -CO-

[0120] (A1-4)-O-Ar a1-4 -CO-

[0121] (Ar a1-3 represents 2,6-naphthylene,

[0122] Ar a1-4 It represents 1,4-phenylene.

[0123] Ar a1-3 or Ar a1-4 The hydrogen atoms in the above groups represented may be independently substituted by halogen atoms, alkyl groups having 1 to 10 carbon atoms, or aryl groups having 6 to 20 carbon atoms.

[0124] When the repeating unit represented by the above formula (A1) includes the repeating unit represented by the above formula (A1-1) and the repeating unit represented by the following formula (A1-2), relative to the total number (100%) of all repeating units constituting the above liquid crystal polyester (A), as an example,

[0125] The number of repeating units represented by the above formula (A1-1) may be more than 40% and less than 90%,

[0126] and the number of repeating units represented by the above formula (A1-2) is 10% or more and less than 60%,

[0127] The number of repeating units represented by the above formula (A1-1) may be 65% or more and 80% or less,

[0128] and the number of repeating units represented by the above formula (A1-2) is 20% or more and 35% or less,

[0129] The number of repeating units represented by the above formula (A1-1) may be 70% or more and 75% or less,

[0130] And the number of the repeating units represented by the above formula (A1-2) is 25% or more and 30% or less.

[0131] When the repeating unit represented by the above formula (A1) includes the repeating unit represented by the above formula (A1-3) and the repeating unit represented by the following formula (A1-4), relative to the total number (100%) of all repeating units constituting the above liquid crystal polyester (A), as an example,

[0132] The number of repeating units represented by the above formula (A1-3) may be more than 40% and less than 90%,

[0133] and the number of repeating units represented by the above formula (A1-4) is 10% or more and less than 60%,

[0134] The number of repeating units represented by the above formula (A1-3) may be 65% or more and 80% or less,

[0135] and the number of repeating units represented by the above formula (A1-4) is 20% or more and 35% or less,

[0136] The number of repeating units represented by the above formula (A1-3) may be 70% or more and 75% or less,

[0137] And the number of the repeating units represented by the above formula (A1-4) is 25% or more and 30% or less.

[0138] The liquid crystal polyester (A) may independently have two or more repeating units represented by the above formula (A1). In addition, the liquid crystal polyester may also have repeating units other than the repeating units represented by the above formula (A1), but the content thereof is preferably 10% or less, more preferably 5% or less relative to the total number (100%) of all repeating units constituting the liquid crystal polyester (A).

[0139] In the present specification, the number of each repeating unit refers to a value determined by the analysis method described in Japanese Patent Application Laid-Open No. 2000-19168.

[0140] Specifically, the liquid crystal polyester resin is reacted with an alcohol having 1 to 3 carbon atoms in a supercritical state to depolymerize the liquid crystal polyester resin to monomers from which its repeating units are derived. The monomers from which each repeating unit is derived, which are obtained as depolymerization products, are quantified by liquid chromatography, and the number of each repeating unit can be calculated.

[0141] The flow start temperature of the liquid crystal polyester is preferably 260°C or higher, more preferably 260°C or higher and 400°C or lower, more preferably 260°C or higher and 380°C or lower, more preferably 260°C or higher and 320°C or lower, further preferably 280°C or higher and 310°C or lower.

[0142] The flow start temperature refers to the temperature at which the liquid crystal polyester is subjected to a flow tester at 9.8 MPa (100 kg / cm 2 ) is heated at a rate of 4°C / min under a load to melt the liquid crystal polyester, and the temperature is such that the liquid crystal polyester exhibits a viscosity of 4800 Pa·s (48000 poise) when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm.

[0143] (Method for producing liquid crystal polyester)

[0144] The liquid crystal polyester is preferably produced by melt-polymerizing raw material monomers corresponding to the repeating units constituting the liquid crystal polyester and, if necessary, solid-phase polymerizing the obtained polymer.

[0145] The melt polymerization can also be carried out in the presence of a catalyst.

[0146] (Composition containing liquid crystal polyester)

[0147] The composition containing the liquid crystal polyester in the present embodiment preferably contains 80% by mass or more of the liquid crystal polyester, more preferably 90% by mass or more, and further preferably 100% by mass, based on 100% by mass of the total mass of the composition.

[0148] The above composition may further contain an optional component other than the above liquid crystal polyester.

[0149] Optional components include fillers, resins other than liquid crystal polyesters, flame retardants, conductive materials, crystal nuclei, ultraviolet absorbers, antioxidants, vibration dampers, antibacterial agents, insect repellents, deodorants, anti-coloring agents, heat stabilizers, mold release agents, antistatic agents, plasticizers, lubricants, dyes, foaming agents, foam inhibitors, viscosity modifiers, surfactants, and the like.

[0150] The composition may be in the form of powder or granules, for example.

[0151] Preferred values ​​of the flow start temperature of the composition include the numerical values ​​exemplified as the flow start temperature of the liquid crystal polyester.

[0152] The larger the difference (FT-Tr) between the temperature (°C) of FT and the temperature (°C) of Tr is, the easier it is to produce a film having a more excellent surface smoothness.

[0153] The value of FT-Tr (°C) may be 15°C or more and 30°C or less, or 18°C ​​or more and 26°C or less.

[0154] According to the film manufacturing method of the present embodiment, it is effective not to set the temperature of the die too high from the viewpoint of improving the surface smoothness of the manufactured film surface. It is believed that this is because: when the setting temperature of the die is higher than FT or Tr, the viscosity of the liquid crystal polyester when ejected from the die decreases and the tension of the film during the manufacturing process becomes insufficient, which becomes a factor that reduces the surface smoothness of the film.

[0155] <Liquid crystal polyester film>

[0156] The film of the embodiment contains a liquid crystal polyester (A) including a repeating unit represented by the following formula (A1),

[0157] (A1)-O-Ar a1 -CO-

[0158] (Ar a1 represents a phenylene group, a naphthylene group or a biphenylene group,

[0159] Ar a1 The hydrogen atoms in the above groups represented may also be independently substituted by halogen atoms, alkyl groups or aryl groups.

[0160] The value of the surface roughness (Ra) is 1.0 μm or less.

[0161] Since the film of the embodiment can be produced from a composition containing a liquid crystal polyester (A), it is excellent in surface smoothness defined by surface roughness Ra.

[0162] The surface roughness (Ra) of the film of the embodiment is 1.0 μm or less, 0.7 μm or less, 0.2 μm or more and 0.7 μm or less. The surface roughness (Ra) may be 0.2 μm or more and 0.6 μm or less, 0.2 μm or more and 0.5 μm or less, 0.3 μm or more and 0.7 μm or less, 0.3 μm or more and 0.6 μm or less, or 0.3 μm or more and 0.5 μm or less.

[0163] In the film of the embodiment, the surface roughness (Ra) value of at least one side of the film is 1.0 μm or less, can be 0.7 μm or less, can be 0.2 μm or more and 0.6 μm or less, can be 0.2 μm or more and 0.5 μm or less, can be 0.3 μm or more and 0.7 μm or more, can be 0.3 μm or more and 0.6 μm or less, can be 0.3 μm or more and 0.5 μm or less.

[0164] In the film of the embodiment, the surface roughness (Ra) value of the film on both sides can be 1.0μm or less, can be 0.7μm or less, can be 0.2μm or more and 0.7μm or less, can be 0.2μm or more and 0.6μm or less, can be 0.2μm or more and 0.5μm or less, can be 0.3μm or more and 0.7μm or less, can be 0.3μm or more and 0.6μm or less, can be 0.3μm or more and 0.5μm or less.

[0165] Examples of the liquid crystal polyester in the liquid crystal polyester film include those exemplified in the method for producing the film of the above-mentioned embodiment.

[0166] The liquid crystal polyester contained in the film of the embodiment may be composed only of the liquid crystal polyester (A).

[0167] Relative to the total number (100%) of all repeating units constituting the above-mentioned liquid crystal polyester (A), the number of repeating units represented by the above-mentioned formula (A1) can be 40% or more, more than 40%, more than 50%, more than 50%, more than 60%, more than 60%, more than 70%, more than 70%, more than 80%, more than 80%, more than 85%, more than 85%, more than 90%, more than 90%, more than 95%, more than 95%, more than 98%, or more than 98%, and can be composed only of the repeating units represented by the above-mentioned formula (A1) (that is, the number of repeating units represented by the above-mentioned formula (A1) can be 100%).

[0168] As the liquid crystal polyester (A) in the liquid crystal polyester film, it is preferred that: it is composed only of repeating units represented by the above formula (A1), and the repeating units represented by the above formula (A1) include repeating units represented by the above formula (A1-3) and repeating units represented by the above formula (A1-4), and it is more preferred that: it is composed only of repeating units represented by the above formula (A1-3) and repeating units represented by the above formula (A1-4).

[0169] The film may further contain an optional component other than the liquid crystal polyester. Examples of the optional component include the components exemplified in the method for producing the film of the above-mentioned embodiment.

[0170] Examples of the types and contents of the liquid crystal polyester contained in the liquid crystal polyester and the optional components that may be contained as desired include the same ones as exemplified in the composition of the method for producing a film according to the above-mentioned embodiment.

[0171] The thickness of the film of the embodiment may be 30 μm or more and 300 μm or less, 30 μm or more and 200 μm or less, or 50 μm or more and 200 μm or less.

[0172] The thickness of the film was set to be the average value of values ​​measured at 9 or more locations at a portion 5 mm or more inside from the outer circumference of the film.

[0173] The film of the embodiment may be a film produced by the method for producing the film of the embodiment described above.

[0174] According to the film of the embodiment, a film having excellent surface smoothness can be provided.

[0175] Example

[0176] Next, the present disclosure will be described in further detail with reference to examples, but the present disclosure is not limited to the following examples.

[0177] 《Measurement / Evaluation》

[0178] [Measurement of Flow Beginning Temperature (FT) of Liquid Crystal Polyester]

[0179] Using a flow tester CFT-500EX (manufactured by Shimadzu Corporation), about 2 g of the liquid crystal polyester was filled into a cylinder equipped with a die having a nozzle with an inner diameter of 1 mm and a length of 10 mm, and the mixture was stirred at 9.8 MPa (100 kg / cm 2 ) under a load of 4°C / min, the liquid crystal polyester was melted and extruded from the nozzle. The temperature at which the liquid crystal polyester showed a viscosity of 4800 Pa·s (48000P) was measured and the temperature was taken as the flow start temperature of the liquid crystal polyester.

[0180] [Determination of Tr of Liquid Crystal Polyester]

[0181] The viscosity of the liquid crystal polyester was measured using a rotational rheometer Discovery HR-20 (manufactured by TA Instruments Co., Ltd.) under the following conditions. The liquid crystal polyester was melted at 360°C and then cooled at a temperature drop rate of 5°C / min. The viscosity of the liquid crystal polyester was 1.0×10 4 The temperature in Pa·s is taken as Tr.

[0182] Measurement start temperature: 360°C

[0183] Cooling speed: 5℃ / min

[0184] Strain: 0.05%

[0185] Frequency: 1Hz

[0186] Use plate: 25mmφ parallel plate

[0187] 〔Film thickness〕

[0188] The film was cut into pieces having a length of 150 mm in the longitudinal direction, and a total of three lines (straight lines) were drawn at positions 5 mm away from both ends in the width direction of the film and at the center.

[0189] Similarly, a total of three lines (straight lines) were drawn at positions 5 mm from both ends and the center in the length direction. The thickness of each part was measured using a U-shaped steel plate micrometer (PMU150-25MJ (Mitutoyo Co., Ltd.)) at the nine points where these six lines intersected, and the arithmetic mean was calculated as the film thickness.

[0190] [Measurement of film surface roughness]

[0191] The arithmetic mean roughness (Ra) in the film width direction was measured using a surface roughness meter (SE600LK31 (manufactured by Kosaka Laboratory Co., Ltd.)) under the following conditions. The arithmetic mean roughness (Ra) was measured on one surface of the film.

[0192] Stylus tip radius: 2μm

[0193] Stylus speed: 0.5mm / sec

[0194] Measuring force: 0.75mN

[0195] Measuring length: 4mm

[0196] Cut-off value: 0.8mm

[0197] "manufacture"

[0198] [Production Example 1]

[0199] ·Manufacturing of Liquid Crystal Polyester

[0200] In a reactor equipped with a stirring device, a torque meter, a nitrogen inlet pipe, a thermometer, and a reflux cooler, 1511.1 g (8.03 mol) of 2-hydroxy-6-naphthoic acid, 410.2 g (2.97 mol) of p-hydroxybenzoic acid, 1291.4 g (12.65 mol) of acetic anhydride, and 0.058 g of 1-methylimidazole were added. The contents were heated from room temperature to 140° C. over 1 hour while stirring under a nitrogen stream, and then stirred at 140° C. for 1 hour.

[0201] Next, while distilling off the by-product acetic acid and unreacted acetic anhydride, the contents are heated from 140°C to 275°C over 2 hours and 50 minutes. After keeping the contents at 275°C for 3 hours, take them out of the reactor. The taken out contents are cooled to room temperature and crushed with a grinder to obtain a powdered liquid crystal polyester (a). The liquid crystal polyester (a) is heated from room temperature to 190°C in a nitrogen atmosphere for 1 hour and 10 minutes, and then heated from 190°C to 260°C for 11 hours and 40 minutes. Then, it is kept at 260°C for 10 hours to perform solid phase polymerization. The obtained solid phase polymer is cooled to room temperature to obtain a powdered liquid crystal polyester (b).

[0202] Next, the liquid crystal polyester (b) was granulated at a barrel temperature of 320° C. using a twin-screw extruder (manufactured by Ikegai Iron Works Co., Ltd., PCM-30) to obtain a granular liquid crystal polyester (c). The flow start temperature (FT) of the liquid crystal polyester (c) was 290° C. The Tr of the liquid crystal polyester (c) was 268° C.

[0203] [Example 1]

[0204] The pelletized liquid crystal polyester (c) produced above is used as a molding material to produce a film by an inflation method.

[0205] The particles (composition) of liquid crystal polyester (c) were put into the barrel of a single-screw extruder with an inner diameter of 20 mm, and kneaded under the conditions of a barrel temperature of 295°C and a screw speed of 30 rpm. The inflation method was used to extrude the composition from an annular die with an inner diameter of 20 mm and a die gap of 1.15 mm, and the film of Example 1 was manufactured with a film folding width of 80 mm.

[0206] The die is composed of three parts, and the temperature of each part can be set independently. The set temperature of each of the three-divided die parts including the annular die part having a spout for spouting the composition is set to 275°C.

[0207] [Examples 2 to 6]

[0208] In Example 1, the film of each of Examples 2 to 6 was produced in the same manner as in Example 1 except that the setting temperature of the die, the barrel temperature, the screw rotation speed, and the film folding width of the device were changed as shown in Table 1. The setting temperature of the three-divided die was set to the same temperature.

[0209] Table 1 shows the results of measuring the above-mentioned items for the liquid crystal polyester and the film.

[0210]

[0211] From the results of Examples 1 to 6, the films of Examples 1 to 6 produced to satisfy the condition of -10≤FT-die set temperature (° C.)≤30 had small values ​​of surface roughness Ra and excellent surface smoothness.

[0212] Industrial Applicability

[0213] According to the present disclosure, a film containing a liquid crystal polyester and having excellent surface smoothness can be produced.

[0214] Explanation of symbols

[0215] 1: Membrane

[0216] 2: Tubular membrane

[0217] 10: Manufacturing device

[0218] 11: Extruder

[0219] 12: Mouth mold

[0220] 14: Guide plate

[0221] 16: Clamping roller

[0222] 111: Barrel

[0223] 112: Screw

[0224] 121: Lower part of the mouth mold

[0225] 122: Middle of the die

[0226] 123: Upper part of the mouth mold

[0227] M: Flow Animal

Claims

1. A method for producing a film, comprising: The composition containing the liquid crystal polyester is extruded from a die under the following conditions to form a film, -10≤FT-The set temperature of the die (℃)≤30 FT: Flow starting temperature (° C.) of the liquid crystal polyester.

2. The method for producing a film according to claim 1, wherein: The set temperature of the die further satisfies the following conditions: -35≤Tr-The set temperature of the die (℃)≤10 Tr: The viscosity of the composition measured under the following measurement conditions is 1.0×10 4 Pa·s Temperature (℃) Determination conditions: Device: Rotational rheometer Cooling speed: 5℃ / min Strain: 0.05% Frequency: 1Hz.

3. The method for producing a film according to claim 1 or 2, wherein: The liquid crystal polyester comprises a liquid crystal polyester (A) comprising a repeating unit represented by the following formula (A1), (A1)-O-Ar a1 -WHAT- Ar a1 represents a phenylene group, a naphthylene group or a biphenylene group, Ar a1 The hydrogen atoms in the groups represented above may be independently substituted by halogen atoms, alkyl groups or aryl groups.

4. The method for producing a film according to claim 3, wherein: The number of the repeating units represented by the formula (A1) exceeds 40% with respect to the total number (100%) of all repeating units constituting the liquid crystal polyester (A).

5. The method for producing a film according to claim 3, wherein: The liquid crystal polyester (A) is composed only of the repeating unit represented by the formula (A1).

6. The method for producing a film according to claim 3, wherein: The liquid crystal polyester (A) comprises a repeating unit represented by the following formula (A1-1): (A1-1)-O-Ar a1-1 -WHAT- Ar a1-1 represents naphthylene, Ar a1-1 The hydrogen atoms in the groups represented above may be independently substituted by halogen atoms, alkyl groups or aryl groups.

7. The method for producing a film according to claim 6, wherein: The number of the repeating units represented by the formula (A1-1) is more than 40% and less than 90% relative to the total number (100%) of the repeating units corresponding to the formula (A1).

8. The method for producing a film according to claim 1 or 2, wherein: The molding is performed by inflation method or T-die method.

9. A film comprising a liquid crystal polyester (A) comprising a repeating unit represented by the following formula (A1): (A1) -O-Ar a1 -CO- Ar a1 represents a phenylene group, a naphthylene group or a biphenylene group, Ar a1 The hydrogen atoms in the groups represented by may also be independently substituted by halogen atoms, alkyl groups or aryl groups. The surface roughness (Ra) of the film is 1.0 μm or less.

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