Insulating resin sheet and manufacturing method thereof

Abstract

To provide an inexpensive insulating resin sheet which can reduce a specific dielectric constant in a frequency band of 800 MHz or more and 30 GHz or less without reducing heat resistance, and a method for manufacturing the same.SOLUTION: An insulating resin film 2 contains 100 pts.mass of a crystalline thermoplastic polyimide resin having a melting point of 300°C or higher, and 0.5 pt.mass or more and 100 pts.mass or less of a fluororesin having melt flowability, is formed by a melt extrusion molding method, and is used for insulation coating of a wire, insulation of a motor, a high frequency circuit board, a thrust washer, and various tapes. An insulating resin film 2 which is excellent in toughness, high heat resistance, high solvent resistance, weather resistance, and flame retardancy can be inexpensively obtained by formed of a crystalline thermoplastic polyimide resin. A specific dielectric constant is reduced and good insulation property can be obtained by adding a fluororesin having excellent dispersibility and melt flowability.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an insulating resin sheet used for insulating coating of electric wires, insulating motors, high-frequency circuit boards, etc., and more particularly to an insulating resin sheet having excellent low dielectric properties and the like, which is made by adding a melt-flowable fluororesin to a crystalline thermoplastic polyimide resin, and a method for producing the same. [Background technology]

[0002] Crystalline thermoplastic polyimide resins having a melting point (crystalline melting temperature) of 300°C or higher are characterized by excellent mechanical properties, heat resistance, dimensional stability, chemical resistance, low water absorption, etc. In light of this, resin films obtained from crystalline thermoplastic polyimide resins are used as substrate films for speaker diaphragms, substrate films for TAB spacer tapes and adhesive tapes, substrate films for RFID tags, various belts used in copiers, printing machines and printers, substrate films for thrust washers, substrate films for various tapes, and in the field of medical devices, for example, substrate films for laser marking labels.

[0003] However, crystalline thermoplastic polyimide resin films usually have a problem of poor insulating properties due to their high relative dielectric constant. Therefore, methods have been proposed to improve the insulating properties by improving the relative dielectric constant of polyimide resin films (see Patent Documents 1 and 2).

[0004] Examples of such methods include: (1) a method of producing a multilayer polyimide resin film by laminating a low-dielectric-constant fluororesin on at least one side of an aromatic polyimide layer via a thermocompression-bondable aromatic polyimide resin, thereby reducing the dielectric constant of the aromatic polyimide resin film (see Patent Document 3); (2) a method of using a fluorine-containing diamine component as the diamine component to reduce the dielectric constant of a polyimide resin film (see Patent Document 4); (3) a method of obtaining a low dielectric constant without impairing the inherent physical properties of a polyimide resin by using a polyimide resin that uses an aromatic diamine of a specific structure and an acid anhydride as monomer components; and (4) a method of using a low-dielectric-constant polyimide resin that is end-capped with an alicyclic dicarboxylic acid anhydride or an alicyclic monoamine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-98002 [Patent Document 2] Japanese Patent Application Laid-Open No. 2020-070359 [Patent Document 3] Patent No. 4029732 [Patent Document 4] Japanese Patent Application Laid-Open No. 2018-165346 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of method (1), although it is possible to obtain a multilayer polyimide resin film with excellent heat resistance and low dielectric properties, the polyimide resin film is produced by a solution casting method, which requires dissolving and drying processes and solvent recovery processes, as well as an imidization process. Furthermore, when multilayering with a fluororesin film, a low-pressure plasma discharge treatment process for the polyimide resin film in the presence of an organic fluorine compound is required, which makes the multilayer polyimide resin film production process very complicated and cumbersome, and also increases the size of the equipment, resulting in new problems such as the high cost of the resulting multilayer polyimide resin film.

[0007] In the case of method (2), although the use of a fluorine-containing diamine component makes it possible to obtain a polyimide resin film with excellent heat resistance, low water absorption, and dimensional stability, a further reduction in the dielectric constant is strongly desired. In addition, the fluorine-containing diamine component is extremely expensive compared to the raw materials used in existing polyimide resin films, and furthermore, new problems arise in that the handling of the fluorine-containing component is extremely difficult in each process. In the case of method (3), in addition to the excellent properties inherent to polyimide resin, thermoplastic polyimide resin can be used, which allows for hot molding. However, the dielectric constant is insufficient, and the dielectric constant in the high frequency range above 1 GHz is unknown.

[0008] In the case of method (4), the resin film obtained from the polyimide resin has good dimensional stability, but the dielectric constant reduction effect is insufficient, so further reduction is desired, and the evaluation of dielectric properties in the high-frequency range above 3 GHz is unknown. Furthermore, when producing resin films using polyimide resins, the production method requires a solution casting process, which requires a dissolving and drying process, making it difficult to produce thick resin films exceeding 50 μm. Furthermore, the need for a dehydration and ring-closing process of polyamic acid (PAA) at temperatures above 200°C makes the production process complicated and cumbersome, leading to the need for larger equipment, resulting in the high cost of the resulting resin film.

[0009] The present invention has been made in consideration of the above, and aims to provide an inexpensive insulating resin sheet that can reduce the relative dielectric constant in the frequency range of 800 MHz or more and 30 GHz or less without reducing heat resistance, and a method for manufacturing the same. [Means for solving the problem]

[0010] As a result of extensive research conducted by the present inventors to solve the above-mentioned problems, they focused on crystalline thermoplastic polyimide resin, which has the highest melting point and excellent heat resistance among thermoplastic resin materials, and fluororesin, which has the lowest relative dielectric constant among thermoplastic resins, and completed the present invention.

[0011] That is, in order to solve the above problems, the present invention provides a thermoplastic crystalline polyimide film containing 100 parts by mass of a crystalline thermoplastic polyimide resin having a melting point of 300°C or higher and 10 to 100 parts by mass of an adhesive fluororesin having melt flowability, and having a relative crystallinity of 95% to 100%. Hereinafter, an insulating resin sheet having a relative dielectric constant of 2.4 or more and 2.8 or less at a frequency of 1 GHz when measured by a cavity resonator perturbation method, and a relative dielectric constant of 2.5 or more and 2.8 or less at a frequency of 28 GHz when measured by a Fabry-Perot method, The adhesive fluororesin contains repeating units (a) based on tetrafluoroethylene and / or chlorotrifluoroethylene, repeating units (b) based on a cyclic hydrocarbon monomer having a dicarboxylic anhydride group and a polymerizable unsaturated group in the ring, and repeating units (c) based on other monomers (however, if the repeating units (a) and (b) overlap, then the repeating units (c) are excluded), and has a melting point of 150°C or higher and 320°C or lower. It is characterized by the following.

[0012] In addition, A fiber sheet can be laminated and integrated with the insulating resin sheet.

[0013] In addition, when the maximum tensile strength is measured in accordance with JIS K 7127, 50MPa or more and 500MPa or less When the tensile elongation at break is measured in accordance with JIS K 7127 100% or more and 500% or less It is preferable that: The crystalline thermoplastic polyimide resin is composed of a tetracarboxylic acid component and a diamine component, and the tetracarboxylic acid component 50 mol% of which The component exceeding this is pyromellitic acid, and the diamine component 50 mol% of which Preferably, more than one component is an aliphatic diamine.

[0014] In addition, in order to solve the above problems, the present invention Claims 1 to 4 was Relative crystallinity is between 95% and 100% A method for manufacturing an insulating resin sheet, comprising: 100 parts by mass of a crystalline thermoplastic polyimide resin having a melting point of 300°C or higher and a melt flowable Adhesive fluororesin 10 parts by mass or more and 100 parts by mass or less The method is characterized in that a molding material containing at least the above is melted and kneaded, the molding material is extruded through a die to form an insulating resin sheet, and the insulating resin sheet is cooled and wound up.

[0015] Here, the term "crystalline thermoplastic polyimide resin" as used in the claims refers to a thermoplastic polyimide resin that has a melting point. In contrast, the term "amorphous thermoplastic polyimide resin" refers to a thermoplastic polyimide resin that does not have a melting point. The melting point (referred to as "crystalline melting") of a crystalline thermoplastic polyimide resin is the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC). The term "insulating resin sheet" includes both thin insulating resin films and thick insulating resin sheets. The insulating resin sheet may be transparent, opaque, translucent, uniaxially oriented, biaxially oriented, or unoriented. The term "fiber sheet" includes both thin fiber films and thick fiber sheets. The fiber sheet is laminated to at least one of the front and back surfaces of the insulating resin sheet to form an integrated structure.

[0016] According to the present invention, an insulating resin sheet is produced using a crystalline thermoplastic polyimide resin, and therefore the insulating resin sheet can be improved in toughness, heat resistance, solvent resistance, weather resistance, flame retardancy, etc. In addition, the insulating resin sheet can be produced using a crystalline thermoplastic polyimide resin having excellent melt fluidity and dispersibility in the crystalline thermoplastic polyimide resin. Adhesive Fluorocarbon Resin Since the insulating resin sheet contains the above-mentioned compound, the relative dielectric constant of the insulating resin sheet is reduced, and good insulating properties can be expected. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an inexpensive insulating resin sheet that can reduce the relative dielectric constant in the frequency range of 800 MHz to 30 GHz without reducing heat resistance. Furthermore, the use of an adhesive fluororesin provides excellent heat resistance and improves dispersibility in the crystalline thermoplastic polyimide resin. The addition of 10 to 100 parts by mass of the adhesive fluororesin eliminates the risk of the dielectric constant of the insulating resin sheet decreasing. Furthermore, the risk of holes occurring during molding of the insulating resin sheet and a decrease in the mechanical strength of the insulating resin sheet can be eliminated. Furthermore, since the insulating resin sheet has a relative crystallinity of 95% or more and 100% or less, problems with the heat resistance of the insulating resin sheet can be prevented. Furthermore, a relative crystallinity of 95% or more is expected to ensure sufficient mechanical strength for use as an insulating resin sheet. Furthermore, the dielectric constant at a frequency of 1 GHz is 2.4 or more and 2.8 or less when measured using the cavity resonator perturbation method, and the dielectric constant at a frequency of 28 GHz is 2.5 or more and 2.8 or less when measured using the Fabry-Perot method. Since the dielectric constant at frequencies of 1 GHz and 28 GHz does not exceed 2.8, dielectric breakdown due to surge voltages can be easily prevented. Additionally, the dielectric constant can be easily reduced in the frequency range of 800 MHz to 30 GHz.

[0018] According to the invention of claim 2, the insulating resin sheet and the fiber sheet are laminated and integrated, so that lipophilicity, heat resistance, flame retardancy, etc. can be improved depending on the application.

[0020] Claim 3 According to the invention, when the maximum tensile strength is measured in accordance with JIS K 7127, 50MPa or more and 500MPa or less When the tensile elongation at break is measured in accordance with JIS K 7127 100% or more and 500% or less Therefore, sufficient toughness can be imparted to the insulating resin sheet, and therefore, for example, when the insulating resin sheet is wound around a rectangular electric wire, the risk of problems such as breakage or cracking can be eliminated, and the winding process can be made easier.

[0021] Claim 4 According to the invention, the tetracarboxylic acid component of the crystalline thermoplastic polyimide resin 50 mol% of which Since the component exceeding this is pyromellitic acid, it is possible to improve the heat resistance, secondary processability, and low water absorption of the insulating resin sheet. 50 mol% of which Since the component exceeding this is an aliphatic diamine, it is possible to improve the heat resistance, low water absorption, moldability, and secondary processability of the insulating resin sheet.

[0022] Claim 5 According to the present invention, since the insulating resin sheet is formed by melt extrusion molding, it is possible to improve the thickness accuracy, productivity, and handleability of the insulating resin sheet. Furthermore, since there is no need to adopt a solution casting method or the like for manufacturing the insulating resin sheet, simplification of manufacturing equipment can be expected. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an overall explanatory view schematically illustrating an insulating resin sheet and a manufacturing apparatus in an embodiment of a manufacturing method thereof according to the present invention; [Figure 2] FIG. 3 is a cross-sectional explanatory view schematically showing a second embodiment of an insulating resin sheet according to the present invention. [Figure 3] FIG. 3 is a cross-sectional explanatory view schematically showing a third embodiment of an insulating resin sheet according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] A preferred embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the insulating resin sheet in this embodiment is an insulating resin film 2 formed into a thin film by melt extrusion molding using a molding material 1 containing a crystalline thermoplastic polyimide resin and a fluororesin. The insulating resin sheet can be used for insulating coating of electric wires, insulating motors, high-frequency circuit boards, thrust washers, various tapes, etc., and thereby contributes to the achievement of Goal 9 of the SDGs (Sustainable Development Goals) adopted at the United Nations Summit.

[0025] The insulating resin film 2 is formed into a thin strip shape by melt extrusion molding using a molding material 1 containing at least 100 parts by mass of a crystalline thermoplastic polyimide (crystalline TPI) resin having a melting point of 300°C or higher and 0.5 to 100 parts by mass of a fluororesin having melt fluidity. The molding material 1 for this insulating resin film 2 contains 100 parts by mass of a crystalline thermoplastic polyimide resin having a melting point of at least 300°C or higher and 0.5 to 100 parts by mass of a fluororesin having excellent insulating properties and adhesiveness and having melt fluidity, and is prepared by kneading the crystalline thermoplastic polyimide resin and the fluororesin having melt fluidity.

[0026] A crystalline thermoplastic polyimide resin is used for molding material 1 because the use of an amorphous thermoplastic polyimide resin results in poor heat resistance, causing the insulating resin film 2 to deform or melt in temperatures exceeding 250°C. This crystalline thermoplastic polyimide resin for molding material 1 has excellent mechanical properties, heat resistance, dimensional stability, chemical resistance, low water absorption, and electrical properties, and is formed into powder, granules, flakes, or pellets. These resins may be used alone or in a blend of two or more types.

[0027] A specific example of the crystalline thermoplastic polyimide resin is a crystalline thermoplastic polyimide resin obtained by cyclodehydration of a polyamic acid obtained by reacting 4,4'-bis(3-aminophenoxy)biphenyl with one or more tetracarboxylic dianhydrides. Tetracarboxylic acid dianhydrides used in thermoplastic polyimide resins obtained by cyclodehydration of polyamic acids obtained by reacting 4,4'-bis(3-aminophenoxy)biphenyl with one or more tetracarboxylic acid dianhydrides include ethylene tetracarboxylic acid dianhydride, cyclopentane tetracarboxylic acid dianhydride, pyromellitic acid dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, 2,2',3,3'-benzophenone tetracarboxylic acid dianhydride, 3,3',4,4'-biphenyl tetracarboxylic acid dianhydride, 2,2',3,3'-biphenyl tetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, and 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride. Examples of suitable tetracarboxylic dianhydrides include bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, and 1,2,7,8-phenanthrenetetracarboxylic dianhydride. Among these, pyromellitic dianhydride is the most suitable. Tetracarboxylic dianhydrides can be used alone or in combination.

[0028] Examples of thermoplastic polyimide resins obtained by cyclodehydration of polyamic acids obtained by reacting 4,4'-bis(3-aminophenoxy)biphenyl with one or more tetracarboxylic dianhydrides include the thermoplastic polyimide resins described in Japanese Patent Publication No. 08-022952. Examples of such products include the Aurum series manufactured by Mitsui Chemicals, Inc.

[0029] The melting point of this crystalline thermoplastic polyimide resin is 300°C or higher, preferably 350°C or higher and 450°C or lower, more preferably 370°C or higher and 430°C or lower, and even more preferably 370°C or higher and 400°C or lower. This crystalline thermoplastic polyimide resin may be a random copolymer, alternating copolymer, block copolymer, or modified product with other copolymerizable monomers, as long as the effects of the present invention are not impaired. The form may be any form, such as powder, flakes, pellets, or blocks.

[0030] Other specific examples of crystalline thermoplastic polyimide resins include those containing a tetracarboxylic acid component and a diamine component primarily composed of an aliphatic diamine component. Examples of the tetracarboxylic acid component of such crystalline thermoplastic polyimide resins include alicyclic tetracarboxylic acids such as cyclobutane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, and cyclohexane-1,2,4,5-tetracarboxylic acid, as well as 3,3',4,4'-diphenylsulfonetetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, biphenyltetracarboxylic acid, naphthalene-1,4,5,8-tetracarboxylic acid, and pyromellitic acid. Alkyl esters of these compounds can also be used.

[0031] Among these, it is preferable that more than 50 mol% of the tetracarboxylic acid component is pyromellitic acid. This is because if the tetracarboxylic acid component is mainly pyromellitic acid, the heat resistance, secondary processability, and low water absorption of the insulating resin film 2 are improved. From this viewpoint, it is preferable that the tetracarboxylic acid component contains 60 mol% or more of pyromellitic acid, more preferably 80 mol% or more, and even more preferably 90 mol% or more. In particular, it is optimal that all (100 mol%) of the tetracarboxylic acid component is pyromellitic acid.

[0032] It is important that the diamine component of the thermoplastic polyimide resin is primarily composed of an aliphatic diamine (including an alicyclic diamine). That is, it is important that more than 50 mol% of the diamine component is an aliphatic diamine, preferably 60 mol% or more, more preferably 80 mol% or more, and particularly preferably 90 mol% or more. In particular, it is optimal that all of the diamine component (100 mol%) is an aliphatic diamine. By using an aliphatic diamine as the primary component, the insulating resin film 2 can be endowed with excellent heat resistance, low water absorbency, moldability, and secondary processability.

[0033] The aliphatic diamine contained in the diamine component is not particularly limited as long as it is a diamine component having amine groups at both ends of a hydrocarbon group. However, when heat resistance is important, it is preferable to include an alicyclic diamine having amine groups at both ends of a cyclic hydrocarbon. Specific examples of this alicyclic diamine include 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 4,4'-diaminodicyclohexylmethane, 4,4'-methylenebis(2-methylcyclohexylamine), isophoronediamine, norbornanediamine, and bis(aminomethyl)tricyclodecane. Among these, 1,3-bis(aminomethyl)cyclohexane is optimal from the viewpoint of achieving both heat resistance, moldability, and secondary processability.

[0034] When emphasis is placed on the melt extrusion moldability of the crystalline thermoplastic polyimide resin and the secondary processability of the insulating resin film 2, it is preferable that the aliphatic diamine contained in the diamine component contains a linear aliphatic diamine having amine groups at both ends of a linear hydrocarbon. This linear aliphatic diamine is not particularly limited as long as it is a diamine component having amine groups at both ends of an alkyl group, and specific examples include ethylenediamine (carbon number 2), propylenediamine (carbon number 3), butanediamine (carbon number 4), pentanediamine (carbon number 5), hexanediamine (carbon number 6), heptanediamine (carbon number 7), octanediamine (carbon number 8), nonanediamine (carbon number 9), decanediamine (carbon number 10), and undecanediamine. (carbon number 11), dodecanediamine (carbon number 12), tridecanediamine (carbon number 13), tetradecanediamine (carbon number 14), pentadecanediamine (carbon number 15), hexadecanediamine (carbon number 16), heptadecanediamine (carbon number 17), octadecanediamine (carbon number 18), nonadecanediamine (carbon number 19), eicosane (carbon number 20), triacontane (carbon number 30), tetracontane (carbon number 40), pentacontane (carbon number 50), etc.

[0035] Among these, linear aliphatic diamines having 4 to 12 carbon atoms are most suitable from the viewpoint of excellent melt extrusion moldability of the crystalline thermoplastic polyimide resin, secondary processability of the insulating resin film 2, and low moisture absorption. These linear aliphatic diamines may also have a branched structure having 1 to 10 carbon atoms.

[0036] The diamine component may contain other diamine components in addition to the aliphatic diamines, specifically, 1,4-phenylenediamine, 1,3-phenylenediamine, 2,4-toluenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, α,α'-bis(4-aminophenyl)-1,4'-diisopropylbenzene, α,α'-bis(3-aminophenyl)-1,4-diisopropylbenzene, 2,2-bis Examples of such diamines include aromatic diamine components such as [4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenyl sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,6-diaminonaphthalene, 1,5-diaminonaphthalene, p-xylylenediamine, and m-xylylenediamine; ether diamine components such as polyethylene glycol bis(3-aminopropyl)ether and polypropylene glycol bis(3-aminopropyl)ether; and siloxane diamines.

[0037] The diamine component may contain either or both of an alicyclic diamine and a linear aliphatic diamine. However, because it provides an excellent balance between heat resistance and moldability, it is preferable to contain both an alicyclic diamine and a linear aliphatic diamine. When both an alicyclic diamine and a linear aliphatic diamine are contained, the respective contents are preferably in the range of alicyclic diamine:linear aliphatic diamine=99:1 to 1:99 mol%, more preferably 90:10 to 10:90 mol%, even more preferably 80:20 to 20:80 mol%, particularly preferably 70:30 to 30:70 mol%, and optimally 60:40 to 40:60 mol%. This is because, as long as the ratio of alicyclic diamine to linear aliphatic diamine contained in the diamine component is within this range, the balance between the heat resistance of the insulating resin film 2 and the melt extrusion moldability of the crystalline thermoplastic polyimide resin can be improved.

[0038] The melting point (also referred to as melting temperature) of the crystalline thermoplastic polyimide resin is 300°C or higher, preferably 300°C or higher and 370°C or lower, more preferably 300°C or higher and 350°C or lower, and even more preferably 310°C or higher and 340°C or lower. This is because if the melting point of the crystalline thermoplastic polyimide resin is lower than 300°C, it is impossible to obtain a heat-resistant insulating resin film 2. On the other hand, if the melting point of the crystalline thermoplastic polyimide resin is higher than 400°C, there is a risk that the melt-flowable fluororesin will decompose violently during the melt extrusion molding of the insulating resin film 2.

[0039] The crystalline thermoplastic polyimide resin may be a random copolymer, an alternating copolymer, a block copolymer, or a modified product with other copolymerizable monomers, provided that the effects of the present invention are not impaired. The crystalline thermoplastic polyimide resin may be in any form, such as powder, flakes, pellets, or blocks.

[0040] The crystalline thermoplastic polyimide resin is not particularly limited, but the thermoplastic polyimide resins described in Japanese Patent Nos. 5365762, 6024859, 6037088, and 6394662 are preferred, and the thermoplastic polyimide resins described in Japanese Patent Nos. 6024859, 6037088, and 6394662 are preferred. Specific examples of this crystalline thermoplastic polyimide resin include the Surprim series (product name, manufactured by Mitsubishi Gas Chemical Company, Inc.), which has high strength, high heat resistance, high solvent resistance, crystallinity, and excellent film formability.

[0041] Such a crystalline thermoplastic polyimide resin composed of a tetracarboxylic acid component and a diamine component mainly composed of an aliphatic diamine component has a melting point of 300°C or higher, preferably 300°C or higher and 370°C or lower, and therefore can be melt extruded at a temperature lower than 400°C. Moreover, decomposition of the fluororesin during molding can be prevented, making it optimal from the standpoint of moldability.

[0042] The fluororesin is preferably a type that has melt fluidity and is solid below its melting point. This is because if it is liquid rather than solid, it will ooze out of the molded insulating resin film 2 and contaminate items that come into contact with the insulating resin film 2. The fluororesin with melt fluidity may be in any form, such as powder, flakes, pellets, or blocks.

[0043] Specific examples of fluororesins having melt flowability include polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resins (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resins, hereinafter referred to as PFA resins, maximum continuous use temperature: 260°C) having a melting point of 302 to 310°C, tetrafluoroethylene-hexafluoropropylene copolymer resins (tetrafluoroethylene-hexafluoropropylene copolymer resins, hereinafter referred to as FEP resins, maximum continuous use temperature: 205°C) having a melting point of 250 to 275°C, and tetrafluoroethylene-ethylene copolymer resins (tetrafluoroethylene-hexafluoropropylene copolymer resins, hereinafter referred to as FEP resins, maximum continuous use temperature: 205°C) having a melting point of 218 to 270°C. Examples include polymer resins (tetrafluoroethylene-ethylene copolymer resin, ETFE resin, maximum continuous use temperature: 150°C), polychlorotrifluoroethylene resins (trifluorochloroethylene resin, PCTFE resin, maximum continuous use temperature: 120°C) with a melting point of 210-216°C, polyvinylidene fluoride resins (vinylidene fluoride resin, PVdF resin, maximum continuous use temperature: 120°C) with a melting point of 160-180°C, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer resins (maximum continuous use temperature: 80-120°C) with a melting point of 120-250°C, and adhesive fluororesins.

[0044] Among these fluororesins, PFA resin, FEP resin, and adhesive fluororesin are preferred from the viewpoints of availability, ease of handling, and cost, as they have excellent heat resistance with a melting point of 250°C or higher and a maximum continuous use temperature of 200°C or higher, and adhesive fluororesin is more preferred because of its excellent dispersibility in crystalline thermoplastic polyimide resin. PFA resin and FEP resin can be used alone or in blends.

[0045] The adhesive fluororesin contains repeating units (a) based on tetrafluoroethylene (hereinafter referred to as TFE) and / or chlorotrifluoroethylene (hereinafter referred to as CTFE), repeating units (b) based on a cyclic hydrocarbon monomer having a dicarboxylic acid anhydride group and a polymerizable unsaturated group in the ring, and repeating units (c) based on other monomers (however, if repeating units (a) and (b) overlap, these monomers are excluded), in order to provide excellent dispersibility in crystalline thermoplastic polyimide resins, melt flowability, chemical resistance, heat resistance, mechanical properties, low dielectric characteristics, etc.

[0046] In such adhesive fluororesin, the repeating units (a) are 50 to 99.89 mol%, the repeating units (b) are 0.01 to 5 mol%, and the repeating units (c) are 0.1 to 49.99 mol%, based on the total molar amount of the repeating units (a), (b), and (c). Preferably, the repeating units (a) are 50 to 99.47 mol%, the repeating units (b) are 0.03 to 3 mol%, and the repeating units (c) are 0.5 to 49.97 mol%, more preferably, the repeating units (a) are 50 to 98.95 mol%, the repeating units (b) are 0.05 to 2 mol%, and the repeating units (c) are 1 to 49.95 mol%.

[0047] This is because, when the mole percentages of the repeating units (a), (b), and (c) are within the ranges, the heat resistance and chemical resistance of the adhesive fluororesin are improved. Also, when the mole percentage of the repeating unit (b) is within the ranges, the adhesiveness of the adhesive fluororesin to the crystalline thermoplastic polyimide resin is improved. Furthermore, when the mole percentage of the repeating unit (c) is within the ranges, the mechanical properties of the adhesive fluororesin, such as moldability and stress crack resistance, are improved.

[0048] The above-mentioned "cyclic hydrocarbon monomer having a dicarboxylic acid anhydride group and a polymerizable unsaturated group in the ring" (hereinafter simply referred to as "cyclic hydrocarbon monomer") refers to a polymerizable compound that is a cyclic hydrocarbon consisting of one or more five- or six-membered rings and that has a dicarboxylic acid anhydride group and a polymerizable unsaturated group in the ring.

[0049] The cyclic hydrocarbon is preferably a cyclic hydrocarbon having one or more bridged polycyclic hydrocarbons. That is, a cyclic hydrocarbon consisting of a bridged polycyclic hydrocarbon, a cyclic hydrocarbon formed by condensing two or more bridged polycyclic hydrocarbons, or a cyclic hydrocarbon formed by condensing a bridged polycyclic hydrocarbon with another cyclic hydrocarbon is preferred. Furthermore, the cyclic hydrocarbon monomer has one or more intracyclic polymerizable unsaturated groups, i.e., polymerizable unsaturated groups present between the carbon atoms constituting the hydrocarbon ring. This cyclic hydrocarbon monomer further has a dicarboxylic acid anhydride group (-CO-O-CO-), which may be bonded to two carbon atoms constituting the hydrocarbon ring or to two carbon atoms outside the ring.

[0050] The dicarboxylic acid anhydride group is preferably a carbon atom constituting the ring of the cyclic hydrocarbon and is bonded to two adjacent carbon atoms. Furthermore, a halogen atom, an alkyl group, a halogenated alkyl group, or other substituent may be bonded to the carbon atom constituting the ring of the cyclic hydrocarbon instead of a hydrogen atom. Specific examples include those represented by the following formulas (1) to (8). Here, R in formulas (2) and (5) to (8) represents a lower alkyl group having 1 to 6 carbon atoms, a halogen atom selected from a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, or a halogenated alkyl group in which a hydrogen atom in the lower alkyl group is substituted with a halogen atom.

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] The cyclic hydrocarbon monomer is preferably 5-norbornene-2,3-dicarboxylic anhydride (hereinafter referred to as NAH) represented by formula (1), cyclic hydrocarbon monomers which are acid anhydrides represented by formulas (3) and (4), and cyclic hydrocarbon monomers in which the substituent R is a methyl group in formulas (2) and (5) to (8). NAH is more preferable.

[0060] Other monomers include vinyl fluoride, vinylidene fluoride (hereinafter referred to as VdF), CTFE (except when used as repeating unit (a)), trifluoroethylene, hexafluoropropylene (hereinafter referred to as HFP), CF2=CFOR f1 (where R f1 is a perfluoroalkyl group having 1 to 10 carbon atoms which may contain an oxygen atom between the carbon atoms, CF2=CFOR f2 SO2X 1 (R f2 is a perfluoroalkylene group having 1 to 10 carbon atoms which may contain an oxygen atom between the carbon atoms, X 1 is a halogen atom or a hydroxyl group), CF2=CFOR f2 CO2X 2 (where R f2is the same as above, X 2 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), CF2=CF(CF2) p OCF=CF2 (where p is 1 or 2), CH2=CX 3 (CF2) q X 4 (where X 3 and X 4 are each independently a hydrogen atom or a fluorine atom, and q is an integer of 2 to 10), perfluoro(2-methylene-4-methyl-1,3-dioxolane), olefins having 2 to 4 carbon atoms such as ethylene, propylene, and isobutene, vinyl esters such as vinyl acetate, and vinyl ethers such as ethyl vinyl ether and cyclohexyl vinyl ether. The other monomers may be used alone or in combination of two or more.

[0061] CF2=CFOR f1 Specific examples include CF2=CFOCF2CF3, CF2=CFOCF2CF2CF3, CF2=CFOCF2CF2CF2CF3, CF2=CFO(CF2)8F, etc. Preferably, CF2=CFOCF2CF2CF3. Also, CH2=CX3(CF2) q X 4 Specific examples include CH2=CH(CF2)2F, CH2=CH(CF2)3F, CH2=CH(CF2)4F, CH2=CF(CF2)3H, CH2=CF(CF2)4H, etc. Preferred is CH2=CH(CF2)4F or CH2=CH(CF2)2F.

[0062] Other monomers are preferably VdF, HFP, CTFE (except when used as repeating unit (a)), CF═CFOR f1 , CH2=CX3(CF2) q X 4 ethylene, propylene, and vinyl acetate, and more preferably HFP, CTFE (except when used as the repeating unit (a)), CF═CF═O═F ... f1 , ethylene, and CH2=CX3(CF2) q X4 The most preferred is HFP or CF₂═CF₄OR. f1 Also, CF2=CFOR f1 As for R f1 Preferably, the group is a perfluoroalkyl group having 1 to 6 carbon atoms, more preferably a perfluoroalkyl group having 2 to 4 carbon atoms, and most preferably a perfluoropropyl group.

[0063] Specific examples of adhesive fluororesins include TFE / CF2=CFOCF2CF2CF3 / NAH copolymer, TFE / HFP / NAH copolymer, TFE / CF2=CFOCF2CF2CF3 / HFP / NAH copolymer, TFE / VdF / NAH copolymer, TFE / CH2=CH(CF2)4F / NAH / ethylene copolymer, TFE / CH2=CH(CF2)2F / NAH / ethylene copolymer, CTFE / CH2=CH(CF2)4F / NAH / ethylene copolymer, CTFE / CH2=CH(CF2)2F / NAH / ethylene copolymer, CTFE / CH2=CH(CF2)2F / NAH / ethylene copolymer, and CTFE / CH2=CH(CF2)2F / NAH / ethylene copolymer.

[0064] The melting point of the adhesive fluororesin is preferably 150° C. or higher and 320° C. or lower, and more preferably 200° C. or higher and 310° C. or lower. This melting point can be adjusted by appropriately selecting the content ratios of the repeating unit (a), the repeating unit (b), and the repeating unit (c) within the above ranges.

[0065] The adhesive fluororesin preferably has an adhesive functional group such as an ester group, carbonate group, hydroxyl group, carboxyl group, carbonyl fluoride group, acid anhydride residue, etc. as the polymer end group, since this provides excellent adhesion to crystalline thermoplastic polyimide resins other than the adhesive fluororesin. Furthermore, the polymer end group having an adhesive functional group can be introduced by appropriately selecting a radical polymerization initiator, a chain transfer agent, etc. during the production of the adhesive fluororesin.

[0066] The method for producing the adhesive fluororesin is not particularly limited, but a radical polymerization method using a radical polymerization initiator is used. Examples of this polymerization method include bulk polymerization, solution polymerization using an organic solvent such as a fluorohydrocarbon, a chlorohydrocarbon, a fluorochlorohydrocarbon, an alcohol, or a hydrocarbon, suspension polymerization using an aqueous medium and, if necessary, an appropriate organic solvent, and emulsion polymerization using an aqueous medium and an emulsifier, with solution polymerization being particularly preferred.

[0067] The adhesive fluororesin is not particularly limited, but preferred examples include the adhesive fluororesins described in Japanese Patent Nos. 4424246, 5263269, and 5365939, or JP 2019-43134 A. Examples of such adhesive fluororesins include LH-8000 (manufactured by AGC Corporation; product name), AH-5000 (manufactured by AGC Corporation; product name), AH-2000 (manufactured by AGC Corporation; product name), and EA-2000 (manufactured by AGC Corporation; product name). Among these adhesive fluororesins, EA-2000, which has excellent heat resistance, is preferred.

[0068] The apparent shear viscosity of fluororesin with melt flowability at a temperature of 350°C is 1 x 10 when a load of 50 kgf is applied. 1 Pa·s or more 1×10 5 Pa·s or less, preferably 1×10 2 Pa·s or more 7×10 4 Pa·s or less, preferably 5×10 2 Pa·s or more 5×10 4 Pa·s or less, more preferably 7×10 2 Pa·s or more 3×10 4 The apparent shear viscosity is set to be within the range of Pa·s or less. This is because, if the apparent shear viscosity is within this range, the fluororesin having melt fluidity can be uniformly dispersed in the crystalline thermoplastic polyimide resin, and it is expected that an insulating resin film 2 having excellent insulation properties, mechanical properties, and slip properties can be produced.

[0069] Conversely, the apparent shear viscosity of a fluororesin with melt flowability is 1 × 10 1If the apparent melt viscosity is less than Pa·s, the dispersibility of the fluororesin having melt fluidity in the crystalline thermoplastic polyimide resin is poor, causing the fluororesin to separate from the insulating resin film 2, resulting in the formation of porosity and a decrease in the quality of the insulating resin film 2. Also, if the apparent melt viscosity of the fluororesin having melt fluidity is less than 1×10 5 If the viscosity exceeds Pa·s, the uniform dispersion of the melt-flowable fluororesin in the crystalline thermoplastic polyimide resin will decrease, causing the melt-flowable fluororesin to form lumps in the insulating resin film 2, resulting in a decrease in insulating properties and mechanical properties.

[0070] If the apparent shear viscosity of the fluororesin having melt fluidity at a temperature of 350°C deviates from the above range, the fluororesin having melt fluidity will separate from the insulating resin film 2, causing the generation of die resin and resulting in a deterioration in the quality of the insulating resin film 2. To explain this point in more detail, when the insulating resin film 2 is molded into a film, a large amount of deposits called die resin may adhere and accumulate at the die exit (also called the die lip). If such die resin accumulates, die lines may appear on the insulating resin film 2, or the die resin may leave the die exit and become mixed into the insulating resin film 2, resulting in a deterioration in the quality of the insulating resin film 2.

[0071] Among fluororesins, polytetrafluoroethylene (PTFE) resin has the best heat resistance and the smallest dielectric constant. However, this polytetrafluoroethylene resin has very low melt fluidity, and its apparent shear viscosity at a temperature of 350°C is 1 x 10 when a load of 50 kgf is applied. 5 Since the dielectric constant of the polytetrafluoroethylene resin exceeds Pa·s or the polytetrafluoroethylene resin does not melt and flow, it cannot be measured. Furthermore, since the melt flowability is very low, when the polytetrafluoroethylene resin is added to a crystalline thermoplastic polyimide resin having a melting point of 300°C or higher and melt-kneaded at a temperature of 300°C or higher, the polytetrafluoroethylene resin melts and aggregates, forming lumps in the crystalline thermoplastic polyimide resin and preventing uniform dispersion. Therefore, it is difficult to produce an insulating resin film 2 with a uniform dielectric constant.

[0072] The amount of the melt-fluidic fluororesin added is preferably 0.5 to 100 parts by mass, preferably 2 to 70 parts by mass, more preferably 5 to 50 parts by mass, and even more preferably 10 to 30 parts by mass, per 100 parts by mass of the crystalline thermoplastic polyimide resin. This is because if the amount of the melt-fluidic fluororesin added is less than 0.5 parts by mass, the dielectric constant of the insulating resin film 2 may not be reduced. On the other hand, if the amount exceeds 100 parts by mass, the melt elongation of the molding material 1 may decrease, which may cause holes to form in the film during molding of the insulating resin film 2 or significantly reduce the mechanical strength of the insulating resin film 2. Furthermore, the molding material 1, which is composed of the molten crystalline thermoplastic polyimide resin and the melt-fluidic fluororesin, may slip within the melt extruder 10, making it impossible to feed the molding material 1 into the melt extruder 10, and as a result, it may not be possible to mold the insulating resin film 2.

[0073] The molding material 1 of the insulating resin film 2 contains a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity, and in addition, within a range that does not impair the characteristics of the present invention, may be a polyolefin resin such as polyethylene (PE) resin, polypropylene (PP) resin, polymethylpentene (PMP) resin, polystyrene (PS) resin, etc., a polyester resin such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polyethylene naphthalate (PEN) resin, etc., a polyimide resin such as polyimide (PI) resin, polyamideimide (PAI) resin, polyetherimide (PEI) resin, etc., a polyamide 4T (PA4T) resin, polyamide 6T (PA6T) resin, modified polyamide 6T (modified PA6T) resin, polyamide 9T (PA9T) resin, etc. The resin composition may contain polyamide resins such as polyamide 10T (PA10T) resin, polyamide 11T (PA11T) resin, polyamide 6 (PA6) resin, polyamide 66 (PA66) resin, and polyamide 46 (PA46) resin; polysulfone resins such as polysulfone (PSU) resin, polyethersulfone (PES) resin, and polyphenylene sulfone (PPSU) resin; polyarylene sulfide resins such as polyphenylene sulfide (PPS) resin, polyphenylene sulfide ketone resin, polyphenylene sulfide sulfone resin, and polyphenylene sulfide ketone sulfone resin; polycarbonate (PC) resin, polyarylate (PAR) resin, polyacetal (POM) resin, liquid crystal polymer (LCP), and aliphatic polyketone resin.

[0074] In addition to the above resins, the molding material 1 may also selectively contain additives such as antioxidants, light stabilizers, ultraviolet absorbers, plasticizers, lubricants, flame retardants, antistatic agents, heat resistance improvers, nucleating agents, inorganic compounds, and organic compounds, as long as the additives do not impair the properties of the present invention.

[0075] In the above, when producing the insulating resin film 2, first, a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity are prepared, and a molding material 1 is prepared from these and fed into a melt extrusion molding machine 10 for molding a resin film, to produce an insulating resin film 2 having a thickness of 1000 μm or less, for example, 1 μm or more and 1000 μm or less.

[0076] The crystalline thermoplastic polyimide resin is preferably heated and dried to reduce its moisture content before melt-kneading with the fluororesin having melt flowability. Examples of heat-drying methods include known methods such as hot air circulation drying, dehumidified hot air drying, heated vacuum drying, and microwave drying. The heat-drying temperature for the crystalline thermoplastic polyimide resin is between −50°C and +50°C, preferably between −30°C and +30°C, more preferably between −20°C and +20°C. The heat-drying time is at least 2 hours, preferably at least 4 hours, and more preferably at least 8 hours. The upper limit of the heat-drying time is not particularly limited, but 24 hours or less is appropriate.

[0077] Methods for preparing molding material 1 include: (1) a method in which a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity are stirred and mixed at room temperature (a temperature range of approximately 0°C to 50°C) to prepare molding material 1; and (2) a method in which, without stirring and mixing the crystalline thermoplastic polyimide resin and the fluororesin having melt fluidity, the fluororesin having melt fluidity is added to molten crystalline thermoplastic polyimide resin, and the mixture is melt-kneaded to prepare molding material 1.

[0078] Regarding the preparation method (1), a known agitator / mixer such as a tumbler mixer, Henschel mixer, V-type mixer, Nautary mixer, ribbon blender, or universal agitator / mixer is used to agitate and mix the crystalline thermoplastic polyimide resin and the fluororesin having melt fluidity. Also, molding material 1 consisting of a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity can be prepared by melt-kneading the agitated mixture consisting of these in a melt-kneader such as a mixing roll, pressure kneader, single-screw extruder, or multi-screw extruder (twin-screw extruder, triple-screw extruder, quadruple-screw extruder, eight-screw extruder, or the like).

[0079] When melt-kneading molding material 1 in a melt-kneader, a vacuum pump can be connected to the vent hole of the melt-kneader and driven to melt-knead molding material 1 under reduced pressure. Melt-kneading under reduced pressure can remove volatile gases such as decomposition gases and moisture contained in the crystalline thermoplastic polyimide resin and the fluororesin having melt fluidity, thereby reducing the moisture content of the crystalline thermoplastic polyimide resin and eliminating the need to heat-dry the crystalline thermoplastic polyimide resin before kneading it with the fluororesin having melt fluidity.

[0080] Furthermore, when preparing molding material 1 using a melt kneader, an inert gas such as helium gas, neon gas, argon gas, krypton gas, or nitrogen gas can be introduced into the raw material inlet of the melt kneader as needed. This effectively prevents oxidation degradation and oxygen crosslinking of the crystalline thermoplastic polyimide resin or the fluororesin having melt fluidity.

[0081] The temperature when melt-kneading the crystalline thermoplastic polyimide resin and the fluororesin having melt fluidity is preferably in the range of not less than the melting point of the crystalline thermoplastic polyimide resin, or not less than the melting point of the fluororesin having melt fluidity but less than the thermal decomposition temperature of the crystalline thermoplastic polyimide resin, or less than the thermal decomposition temperature of the fluororesin having melt fluidity.

[0082] Specifically, the temperature is preferably 280° C. or higher and lower than 400° C., preferably 300° C. or higher and 370° C. or lower, and more preferably 330° C. or higher and 360° C. This is because if the temperature is lower than the melting point of the crystalline thermoplastic polyimide resin or the melting point of the fluororesin having melt fluidity, it will be difficult to prepare molding material 1, and if the temperature is higher than the thermal decomposition temperature of the crystalline thermoplastic polyimide resin or the thermal decomposition temperature of the fluororesin having melt fluidity, there is a risk of the crystalline thermoplastic polyimide resin or the fluororesin having melt fluidity being violently decomposed.

[0083] When a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity are mixed by stirring, a predetermined amount or more of the fluororesin having melt fluidity can be dispersed in the crystalline thermoplastic polyimide resin to form a masterbatch. Furthermore, a molding material 1 consisting of a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity can be extruded into a strand or sheet shape, and then processed into a form suitable for molding into an insulating resin film 2, such as powder, granules, or pellets, using a grinder or cutter.

[0084] Next, the preparation method (2) will be explained. In this preparation method, first, a crystalline thermoplastic polyimide resin is melt-kneaded in a melt kneader such as a mixing roll, a pressure kneader, a Banbury mixer, a single-screw extruder, or a multi-screw extruder (twin-screw extruder, triple-screw extruder, four-screw extruder, eight-screw extruder, etc.), and then a fluororesin having melt fluidity is added to the crystalline thermoplastic polyimide resin and melt-kneaded to prepare a molding material 1 containing a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity.

[0085] When the molding material 1 is melt-kneaded in a melt-kneader, a vacuum pump may be connected to the vent hole of the melt-kneader, and the vacuum pump may be driven to melt-knead the molding material 1 under reduced pressure, as described above. Melt-kneading under reduced pressure can remove volatile gases such as decomposition gases and moisture contained in the crystalline thermoplastic polyimide resin and the fluororesin having melt fluidity, which is expected to reduce the moisture content of the crystalline thermoplastic polyimide resin and eliminate the need to heat-dry the crystalline thermoplastic polyimide resin before kneading it with the fluororesin having melt fluidity.

[0086] When preparing molding material 1 using a melt kneader, as described above, an inert gas such as helium gas, neon gas, argon gas, krypton gas, or nitrogen gas can be introduced into the raw material inlet of the melt kneader as needed. This introduction effectively prevents oxidative degradation and oxygen crosslinking of the crystalline thermoplastic polyimide resin and the fluororesin having melt fluidity.

[0087] The temperature when melt-kneading the crystalline thermoplastic polyimide resin and the melt-fluidic fluororesin is preferably in the range of above the melting point of the crystalline thermoplastic polyimide resin, above the melting point of the melt-fluidic fluororesin but below the thermal decomposition temperature of the crystalline thermoplastic polyimide resin, or below the thermal decomposition temperature of the melt-fluidic fluororesin. Specifically, it is 280°C or higher but below 400°C, preferably 300°C or higher but below 370°C, and more preferably 330°C or higher but below 360°C. This is because, if the temperature is lower than the melting point of the crystalline thermoplastic polyimide resin or the melting point of the melt-fluidic fluororesin, it becomes difficult to prepare the molding material 1, and if the temperature is higher than the thermal decomposition temperature of the crystalline thermoplastic polyimide resin or the melt-fluidic fluororesin, the crystalline thermoplastic polyimide resin or the melt-fluidic fluororesin may decompose violently.

[0088] When a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity are mixed by stirring, a masterbatch can be formed by dispersing a predetermined amount or more of the fluororesin having melt fluidity in the crystalline thermoplastic polyimide resin. Furthermore, a molding material 1 made of a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity can be extruded into a strand or sheet shape, and then processed into a powder, granules, pellets, or other form suitable for molding into an insulating resin film 2 using a grinder or cutter.

[0089] The moisture content (water content) of the molding material 1 before being fed into the melt extrusion molding machine 10 is adjusted to 2000 ppm or less, preferably 1000 ppm or less, and more preferably 500 ppm or less, using a hot air dryer or the like, because if the moisture content exceeds 2000 ppm, foaming of the insulating resin film 2 may occur.

[0090] When an insulating resin film 2 is produced using a molding material 1 containing a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity, known manufacturing methods such as melt extrusion, calendar molding, or casting can be used. However, from the viewpoints of improving the thickness accuracy, productivity, and handleability of the insulating resin film 2, and simplifying the equipment, the melt extrusion method, in which the insulating resin film 2 is continuously extruded into a strip, is optimal. Here, the melt extrusion method is a molding method in which the molding material 1 is melt-kneaded using a melt extruder 10, as shown in FIG. 1, and the insulating resin film 2 is continuously extruded through a die consisting of a T-shaped die 13 of the melt extruder 10.

[0091] The melt extruder 10 is, for example, a single-screw extruder or a twin-screw extruder, and functions to melt and knead the introduced molding material 1. A raw material inlet 11 for the molding material 1 is provided at the upper rear of the melt extruder 10, and an inert gas supply pipe 12 is connected to this raw material inlet 11, which supplies an inert gas such as helium gas, neon gas, argon gas, krypton gas, nitrogen gas, or carbon dioxide gas as needed. The inflow of the inert gas through this inert gas supply pipe 12 is expected to effectively prevent oxidation degradation and oxygen crosslinking of the molding material 1.

[0092] The temperature during melt kneading in the melt extruder 10 is preferably in the range of not less than the melting point of the crystalline thermoplastic polyimide resin, not less than the melting point of the fluororesin having melt fluidity and less than the thermal decomposition temperature of the crystalline thermoplastic polyimide resin, or less than the thermal decomposition temperature of the fluororesin having melt fluidity. Specifically, the temperature is preferably not less than 280°C and less than 400°C, more preferably not less than 300°C and less than 370°C, and even more preferably not less than 330°C and less than 360°C.

[0093] This is because melt extrusion molding of molding material 1 becomes difficult if the temperature is below the melting point of the crystalline thermoplastic polyimide resin or the melting point of the fluororesin having melt fluidity, and if the temperature is above the thermal decomposition temperature of the crystalline thermoplastic polyimide resin or the fluororesin having melt fluidity, there is a risk that the crystalline thermoplastic polyimide resin or the fluororesin having melt fluidity will decompose violently.

[0094] The T-die 13 is attached to the tip of the melt extruder 10 via a connecting pipe 14, and functions to continuously extrude the strip-shaped insulating resin film 2 toward a plurality of pressure rolls 16 and a cooling roll 17 located below. The temperature during extrusion through the T-die 13 is in the range of the melting point of the crystalline thermoplastic polyimide resin, or the melting point of the fluororesin having melt fluidity, but below the thermal decomposition temperature of the crystalline thermoplastic polyimide resin, or below the thermal decomposition temperature of the fluororesin having melt fluidity.

[0095] Specifically, the temperature is adjusted to 280° C. or higher and 400° C. or lower, preferably 300° C. or higher and 370° C. or lower, and more preferably 330° C. or higher and 360° C. or lower. This is also based on the same reason as above, which is that melt extrusion molding of molding material 1 may be hindered and the crystalline thermoplastic polyimide resin or the fluororesin having melt fluidity may be severely decomposed.

[0096] A gear pump 15 and a filter are preferably attached to the connecting pipe 14 upstream of the T-die 13. The gear pump 15 transfers the molding material 1 melt-kneaded by the melt extruder 10 to the downstream filter at a constant flow rate and with high precision. The filter also separates gels, foreign matter, etc. from the molten molding material 1 and transfers the molten molding material 1 to the downstream T-die 13.

[0097] The filter is made of, for example, a circle with many concentric holes, sintered metal with many holes, or a metallic mesh, and has a plurality of small openings that are 0.5 to 6 times, preferably 0.5 to 4 times, and more preferably 0.5 to 3.8 times the average thickness of the insulating resin film 2. The reason why the openings in the filter are 0.5 times or more is that if the openings are less than 0.5 times, the extrusion pressure of the molding material 1 will be too high, which could damage the filter and significantly reduce productivity.

[0098] A plurality of (pairs of) pressure rolls 16 are rotatably supported below the T-die 13 and sandwich a plurality of cooling rolls 17 lined up horizontally so as to be in sliding contact with each other. A take-up tube 19 of a winder 18 that winds up the insulating resin film 2 is rotatably installed downstream of the downstream pressure roll 16 among the plurality of pressure rolls 16, and a slit blade 20 that forms a slit in the side of the insulating resin film 2 is arranged between the pressure roll 16 and the take-up tube 19 of the winder 18 so as to be able to rise and fall. A required number of rotatable tension rolls 21 are supported between the slit blade 20 and the take-up tube 19 of the winder 18 to apply tension to the insulating resin film 2 for smooth winding.

[0099] To improve the adhesion between the insulating resin film 2 and the cooling roll 17, the peripheral surface of each pressure roller 16 is coated as needed with a rubber layer made of at least natural rubber, isoprene rubber, butadiene rubber, silicone rubber, fluororubber, or the like, and an inorganic compound such as silica or alumina is selectively added to this rubber layer. Of these, silicone rubber and fluororubber, which have excellent heat resistance, are preferably used.

[0100] A metal elastic roll with a metal surface may be used as the pressure-bonding roll 16 as needed, and when this metal elastic roll is used, it becomes possible to form an insulating resin film 2 with an excellent surface smoothness. Examples of such metal elastic roll products include a metal sleeve roll, an air roll (product name manufactured by Dymco Corporation), and a UF roll (product name manufactured by Hitachi Zosen Corporation).

[0101] Such pressure roller 16 is adjusted to a temperature of 240°C or less, preferably 50°C to 220°C, more preferably 130°C to 200°C, and even more preferably 160°C to 200°C, and is brought into sliding contact with insulating resin film 2 and pressed against cooling roller 17. The reason why the temperature of pressure roller 16 is within this range is that if the temperature of pressure roller 16 exceeds 240°C, the insulating resin film 2 during production may stick to pressure roller 16, causing the insulating resin film 2 to break or the rubber layer coated on pressure roller 16 to thermally decompose.

[0102] Conversely, it is not preferable for the temperature of the pressure roller 16 to be less than 50°C, as this will cause condensation on the pressure roller 16. Methods for adjusting the temperature or cooling the pressure roller 16 include methods using a heat medium such as air, water, or oil, or methods using an electric heater or a dielectric heating roller.

[0103] The multiple cooling rolls 17 are, for example, metal rolls with a larger diameter than the pressure roll 16, and are rotatably arranged and journaled below the T-die 13 to sandwich the extruded insulating resin film 2 between adjacent pressure rolls 16, and function to control the thickness of the insulating resin film 2 within a predetermined range while cooling it together with the pressure roll 16. Like the pressure roll 16, each cooling roll 17 is adjusted to a temperature of 240°C or less, preferably 50°C to 220°C, more preferably 130°C to 200°C, and even more preferably 160°C to 200°C, and comes into sliding contact with the insulating resin film 2.

[0104] The reason why the temperature of the cooling roll 17 is adjusted to a temperature of 50°C or higher and 240°C or lower is that if the temperature of the cooling roll 17 exceeds 240°C, the insulating resin film 2 during production may adhere to the cooling roll 17, causing breakage of the insulating resin film 2, or, in the case of a pressure roll 16 coated with an adjacent rubber layer, the rubber layer of the pressure roll 16 may thermally decompose. On the other hand, if the temperature of the cooling roll 17 is lower than 50°C, condensation will occur on the cooling roll 17, which is undesirable. As with the above, methods for adjusting the temperature of the cooling roll 17 and cooling it include methods using a heat medium such as air, water, or oil, or electric heaters or induction heating.

[0105] 1, when producing an insulating resin film 2, a molding material 1 is fed into a raw material inlet 11 of a melt extruder 10 while an inert gas is being supplied, and the molding material 1 is melt-kneaded under heat and pressure by the melt extruder 10, and a thin insulating resin film 2 is continuously extruded into a strip from a T-die 13. After the strip-shaped insulating resin film 2 is extruded in this manner, it is wound sequentially around a pair of pressure rolls 16, multiple cooling rolls 17, a tension roll 21, and a take-up tube 19 of a winder 18. After the insulating resin film 2 is cooled by the cooling roll 17, both sides of the insulating resin film 2 are cut with a slit blade 20, and the insulating resin film 2 is wound sequentially around the take-up tube 19, thereby producing the insulating resin film 2.

[0106] During the production of the insulating resin film 2, fine irregularities can be formed on the front and back surfaces of the insulating resin film 2 to a degree that does not impair the effects of the present invention, thereby reducing the coefficient of friction on both surfaces of the insulating resin film 2. Examples of methods for forming the fine irregularities include (1) a method in which the insulating resin film 2 is sandwiched between a pressure roll 16 and a cooling roll 17 that have fine irregularities to form the fine irregularities; (2) a method in which fine irregularities are formed by spraying the insulating resin film 2 with minute inorganic compounds such as zirconia, glass, or stainless steel, or organic compounds such as polycarbonate resin, polyamide resin, or plant seeds; and (3) a method in which the insulating resin film 2 is press-molded in a mold that has fine irregularities to form the fine irregularities. Of these methods, method (1) is optimal in terms of simplified equipment, accurate irregularity size, uniform irregularity formation, ease of irregularity formation, and the ability to continuously form irregularities.

[0107] To explain method (1) in more detail, there are (1-1) a method in which a stirred mixture of a crystalline thermoplastic polyimide resin and a fluororesin having melt fluidity is melt-kneaded in a melt extruder 10 to prepare a molding material 1, and this molding material 1 is extruded from a T-shaped die 13 of the melt extruder 10 onto a cooling roll 17 having fine irregularities on its peripheral surface, and this extruded material is sandwiched between a pressure roll 16 and a cooling roll 17 having fine irregularities on their peripheral surfaces, and molded simultaneously with the melt extrusion molding of an insulating resin film 2, and (1-2) a method in which the molded insulating resin film 2 is sandwiched between a pressure roll 16 and a cooling roll 17 having fine irregularities on their peripheral surfaces, and the irregularities are formed. Of these, method (1-1) is preferred from the viewpoint of simplifying the equipment.

[0108] The thickness of the insulating resin film 2 after cooling is preferably in the range of 1 μm to 1000 μm, more preferably 5 μm to 750 μm, more preferably 10 μm to 500 μm, and even more preferably 25 μm to 300 μm. This is because if the thickness of the insulating resin film 2 is less than 1 μm, the mechanical strength of the insulating resin film 2 will be significantly reduced, making it difficult to mold the insulating resin film 2.

[0109] Conversely, if the thickness of the insulating resin film 2 exceeds 1000 μm, the molding speed drops significantly, resulting in lower productivity. Furthermore, if the insulating resin film 2 exceeds 1000 μm, when the insulating resin film 2 is used as an insulating material for a motor, the occupancy rate of the conductive windings in the motor's core slot decreases, creating problems with miniaturization and high output of the motor. The thickness of this insulating resin film 2 can be measured using various contact thickness gauges.

[0110] The relative crystallinity of the insulating resin film 2 is 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 100%. This is because if the relative crystallinity of the insulating resin film 2 is less than 80%, problems will arise with the heat resistance of the insulating resin film 2. Furthermore, if the relative crystallinity is 80% or more, it is expected that the insulating resin film 2 will have sufficient mechanical strength to be usable as an insulating resin film 2. The crystallinity of the insulating resin film 2 can be expressed in terms of the relative crystallinity. The relative crystallinity of the insulating resin film 2 is calculated by the following formula based on the results of thermal analysis measured at a heating rate of 10°C / min using a differential scanning calorimeter.

[0111] Relative crystallinity (%) = {1-(ΔHc / ΔHm)} × 100 ΔHc: Heat quantity of the recrystallization peak of the insulating resin film (J / g) ΔHm: Heat of melting peak of insulating resin film (J / g)

[0112] From the viewpoint of satisfying the insulation property, slipperiness, mechanical properties, heat resistance, etc. of the insulating resin film 2, the insulation property is preferably 2.8 or less, preferably 2.6 or less, when the relative dielectric constant at a frequency of 1 GHz is measured by a cavity resonator perturbation method, and 2.8 or less, preferably 2.6 or less, more preferably 2.5 or less, and even more preferably 2.4 or less, when the relative dielectric constant at a frequency of 28 GHz is measured by a Fabry-Perot method. The lower limit of the relative dielectric constant at frequencies of 1 GHz and 28 GHz is not particularly limited, but is practically 1.1 or more.

[0113] This is because if the dielectric constant exceeds 2.8 at frequencies of 1 GHz and 28 GHz, the partial discharge breakdown voltage, which is the initial phenomenon of dielectric breakdown, cannot be increased sufficiently, making it difficult to prevent dielectric breakdown due to surge voltage. Also, it is difficult to reduce the dielectric constant in the frequency range from 800 MHz to 30 GHz.

[0114] The mechanical properties of the insulating resin film 2 can be evaluated by the maximum tensile strength, tensile elongation at break, and tensile modulus at 23°C. The maximum tensile strength of the insulating resin film 2 is 50 MPa or more, preferably 60 MPa or more, when measured in accordance with JIS K 7127. There are no particular restrictions on the upper limit of this maximum tensile strength, but it is preferably 500 MPa or less.

[0115] The tensile elongation at break of the insulating resin film 2, measured in accordance with JIS K 7127, is preferably 100% or more, preferably 150% or more, and more preferably 200% or more. There are no particular restrictions on the upper limit of this tensile elongation at break, but it is preferably 500% or less. This is because if the maximum tensile strength is less than 50 MPa and the elongation at break is less than 100%, the insulating resin film 2 does not have sufficient toughness, and there is a risk of problems such as breakage or cracking when winding the insulating resin film 2 around a rectangular electric wire, making the winding process difficult.

[0116] The tensile modulus of the insulating resin film 2 at 23°C, when measured in accordance with JIS K 7127, is optimally in the range of 1000 MPa or more and 5000 MPa or less, preferably 1250 MPa or more and 3000 MPa or less, more preferably 1500 MPa or more and 2750 MPa or less, and even more preferably 1500 MPa or more and 2500 MPa or less.

[0117] This is because if the tensile modulus of the insulating resin film 2 is less than 1000 MPa, the rigidity of the insulating resin film 2 is poor, which reduces the handling properties when winding the insulating film around the conductive wire, and causes a large deviation in the laminated state of the insulating resin film 2 when bending the conductive wire. Also, when the insulating resin film 2 is used as an insulating material for rotating electrical appliances, the insulating material for rotating electrical appliances buckles when inserted into a core slot of a rotating electrical machine. Conversely, if the tensile modulus of the insulating resin film 2 is less than 5000 N / mm 2If the bending strength exceeds 1000 MPa, the insulating resin film 2 will peel off from the conductive wires due to excessive rigidity during bending. Furthermore, if the insulating resin film 2 is used as an insulating material for rotating electrical appliances, it will crack during bending.

[0118] The sliding properties of the insulating resin film 2 can be expressed by the static friction coefficient (μs) and the dynamic friction coefficient (μk). The static friction coefficient of sliding properties, when measured in accordance with JIS K 7125-1999, is 0.5 or less, preferably 0.4 or less, and more preferably 0.3 or less. The dynamic friction coefficient, when measured in accordance with JIS K 7125-1999, is also 0.5 or less, preferably 0.4 or less, and more preferably 0.3 or less. This is because if the static friction coefficient and the dynamic friction coefficient exceed 0.5, sufficient sliding properties cannot be obtained, and the occurrence of wrinkles during winding of the insulating resin film 2 cannot be prevented. There are no particular restrictions on the lower limits of these static friction coefficients and dynamic friction coefficients, but a value of 0.01 or more is preferred.

[0119] The heat resistance of the insulating resin film 2 can be evaluated by the storage modulus (E') at 260°C. The storage modulus (E') at 260°C is 1×10 6 Pa or more, preferably 5 x 10 6 Pa or more, more preferably 1×10 7 Pa or more, more preferably 5×0 7 This means that the storage modulus is 1×10 6 If the storage modulus of the insulating resin film 2 at 260°C is less than 1 × 10 6 When the storage modulus is 1×10 Pa or more, it can be used as an insulating resin film 2 having a heat resistance class of H. The upper limit of the storage modulus of the insulating resin film 2 is not particularly limited, but is preferably 1×10 10 Pa or less is better.

[0120] The water absorption of the insulating resin film 2, measured in accordance with JIS K 7209 Method A, is less than 1.0% at 23°C, but is preferably 0.8% or less, and more preferably 0.6% or less. This is because, when the water absorption at 23°C is less than 1.0%, high electrical insulation can be maintained even in a high-temperature, humid environment. The lower the water absorption of this insulating resin film 2 at 23°C, the better, but for practical purposes it is 0% or more.

[0121] According to the above, since the insulating resin film 2 is molded by melt extrusion molding, it is possible to simplify the manufacturing process and reduce the size of the manufacturing equipment, and it is possible to provide the insulating resin film 2 at low cost. Furthermore, since the molding material 1 contains a crystalline thermoplastic polyimide resin, it is possible to obtain the insulating resin film 2 at low cost, which has excellent toughness, high heat resistance, high solvent resistance, weather resistance, flame retardancy, etc. Therefore, even if the insulating resin film 2 is used for insulating motors at temperatures of 160°C or higher, it will not deform or break.

[0122] Furthermore, by adding a fluororesin with excellent dispersibility and melt fluidity to the crystalline thermoplastic polyimide resin, the dielectric constant is reduced, making it possible to obtain good insulation. Therefore, it is possible to reduce the dielectric constant in the frequency range of 800 MHz to 30 GHz. Furthermore, the excellent dispersibility of the fluororesin provides good slip properties, and the insulating resin film 2 is less likely to wrinkle when wound up.

[0123] Next, Figure 2 shows a second embodiment of the present invention, in which a thin film-type nonwoven fabric 3, which is a fiber sheet, is directly laminated on the underside or both sides of an insulating resin film 2 by thermocompression bonding. The nonwoven fabric 3 is formed of, for example, polyaramid fiber, polyarylene ether ketone fiber, polyetherimide fiber, polyarylene sulfide fiber, polypropylene resin fiber, polyester resin fiber, fluororesin fiber, carbon fiber, etc. The nonwoven fabric 3 may be single-layered or multi-layered. The other parts are the same as those in the above embodiment, so a description thereof will be omitted.

[0124] In this embodiment, the same effects as those of the above embodiment can be expected, and it is clear that excellent lipophilicity, heat resistance, flame retardancy, filtering properties, sound absorption properties, etc. can be obtained by employing the nonwoven fabric 3. Furthermore, when the insulating resin film 2 is used for insulating a motor, it can be made to be more compatible with insulating oil.

[0125] Next, Figure 3 shows a third embodiment of the present invention, in which a thin film-type nonwoven fabric 3, which is a fiber sheet, is laminated on the underside or both sides of an insulating resin film 2 via an adhesive layer 4 made of adhesive. The adhesive layer 4 is formed by printing an adhesive such as an acrylic, urethane, epoxy, or silicone adhesive, and then drying and hardening it. The other parts are the same as those in the above embodiment, so a description thereof will be omitted.

[0126] In this embodiment, the same effects as those of the above embodiment can be expected, and it is clear that the use of adhesive layer 4 enables the insulating resin film 2 and nonwoven fabric 3 to be firmly bonded and integrated. [Example]

[0127] Examples of the insulating resin film and the method for producing the same according to the present invention will be described below together with comparative examples. Example 1 First, a commercially available thermoplastic polyimide resin (manufactured by Mitsubishi Gas Chemical Co., Inc., product name: Surprim TO65 (hereinafter abbreviated as "TO65")) was prepared as the crystalline thermoplastic polyimide resin. This thermoplastic polyimide resin was placed in a dehumidified hot air dryer heated to 160°C and dried for at least 12 hours. Then, 3 parts by mass of PFA resin (manufactured by Daikin Industries, Ltd., product name: Neoflon PFA AP-201 (hereinafter abbreviated as AP-201)), a fluororesin with melt fluidity, was weighed out per 100 parts by mass of the crystalline thermoplastic polyimide resin. The two resins were then placed in a mixer and stirred to prepare a stirred mixture. Hereinafter, this crystalline thermoplastic polyimide resin will be referred to as crystalline TPI resin.

[0128] The melting point (also called melting temperature) of the crystalline TPI resin was measured using a differential scanning calorimeter (SII NanoTechnology, product name: High Sensitivity Differential Scanning Calorimeter X-DSC7000) in accordance with JIS K7121 at a heating rate of 10°C / min. The melting point of the crystalline TPI resin was measured to be 324°C.

[0129] Once the stirred mixture was prepared, it was fed into the raw material inlet of a vented co-rotating twin-screw extruder and melted. The molten mixture was extruded into rods through the die at the end of the co-rotating twin-screw extruder. After water cooling, the extruded mixture was cut into pellets using a pelletizer to prepare pellet-shaped molding materials. The co-rotating twin-screw extruder was a φ42 mm, L / D=38 type. The stirred mixture was melt-kneaded under conditions of a cylinder temperature of 300-350°C and a die temperature of 350°C, with the vent on the raw material inlet side of the co-rotating twin-screw extruder open and the vent on the die side degassed under reduced pressure. The temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was measured to be 345°C.

[0130] The apparent shear viscosity of the crystalline TPI resin was measured using a flow tester (Shimadzu Corporation, product name: Shimadzu Flow Tester CFT-500D). 3The mixture was packed into a cylinder at 350°C attached to a die (diameter: 1 mm, length: 10 mm), and a 1.0 cm2 tube was placed on top of the cylinder. 2 After the temperature of the cylinder reached 350°C, it was preheated for 5 minutes, and immediately after this preheating, a load of 50 kgf was applied to melt and flow out the fluororesin, and its shear viscosity was measured.

[0131] The prepared molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for at least 12 hours. The dried molding material was then placed in a φ40 mm single-screw extruder equipped with a 900 mm wide T-die. The melt-kneaded molding material was continuously extruded through the T-die of the single-screw extruder to extrude an insulating resin film into a strip. The moisture content of the molding material was measured by Karl Fischer titration using a trace moisture analyzer (Mitsubishi Chemical Corporation, product name: CA-100). The moisture content of the molding material was found to be 300 ppm or less. The moisture content of this molding material was subsequently measured using the same method.

[0132] The single-screw extruder had an L / D ratio of 32, a compression ratio of 2.5, and a full-flight screw. The cylinder temperature of the single-screw extruder was adjusted to 250-350°C, the T-die temperature to 350°C, and the temperature of the connecting pipe connecting the single-screw extruder and the T-die to 350°C. A gear pump was attached to the connecting pipe, and the temperature of this gear pump was adjusted to 350°C. When the molding material was introduced into the single-screw extruder, nitrogen gas was supplied at a rate of 18 L / min. The temperature of the molten molding material was measured by measuring the resin temperature at the inlet of the T-die, which was found to be 352°C.

[0133] After the insulating resin film was formed, the continuous insulating resin film was clamped between a pressure roll and a cooling roll to cool it, and both sides of the insulating resin film were cut with a slit blade and sequentially wound onto a winding tube of a winding machine, thereby producing an insulating resin film 100 m long and 620 mm wide.

[0134] Once the insulating resin film was produced in this way, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulation, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are summarized in Table 1. The insulation properties of the insulating resin film were evaluated by the relative dielectric constant at frequencies of 1 GHz and 28 GHz, the mechanical properties by the tensile strength, tensile elongation at break, and tensile modulus, the slipperiness by the static friction coefficient (hereinafter abbreviated as "μs") and the dynamic friction coefficient (hereinafter abbreviated as "μk"), and the heat resistance by the storage modulus (E') at 260°C.

[0135] Apparent shear viscosity of fluororesin with melt flowability The apparent shear viscosity of the fluororesin having melt flowability was measured using a flow tester (Shimadzu Corporation, product name: Shimadzu Flow Tester CFT-500D). 3 The mixture was packed into a cylinder at 350°C attached to a die (diameter: 1 mm, length: 10 mm), and a 1.0 cm2 tube was placed on top of the cylinder. 2 A plunger was attached, and when the temperature of the cylinder reached 350°C, it was preheated for 5 minutes, and immediately after this preheating, a load of 50 kgf was applied, causing the fluororesin having melt fluidity to melt and flow out, and its shear viscosity was measured.

[0136] ·Insulating resin film thickness The thickness of the insulating resin film was measured using a micrometer (Mitutoyo Corporation, product name: Coolant-proof micrometer, model MDC-25PJ) at 10 random locations in the width direction of the insulating resin film (the direction perpendicular to the extrusion direction (hereinafter abbreviated as "TD")), and the average value was used as the film thickness.

[0137] Relative crystallinity of insulating resin film The relative crystallinity of the insulating resin film was measured by weighing approximately 5 mg of a measurement sample from the insulating resin film and using a differential scanning calorimeter (manufactured by SII Nanotechnologies, Inc., product name: EXSTAR7000 series X-DSC7000) at a heating rate of 10°C / min over a temperature range of 20°C to 380°C. The heat quantity (J / g) of the melting peak and the heat quantity (J / g) of the recrystallization peak obtained at this time were used to calculate the crystallinity using the following formula.

[0138] Relative crystallinity (%) = {1-(ΔHc / ΔHm)} × 100 Here, ΔHc represents the heat quantity (J / g) of the recrystallization peak of the insulating resin film when the temperature is increased at 10°C / min, and ΔHm represents the heat quantity (J / g) of the melting peak of the insulating resin film when the temperature is increased at 10°C / min.

[0139] ·Insulating properties of insulating resin film The insulating properties of the insulating resin film were evaluated by the relative dielectric constant at frequencies of 1 GHz and 28 GHz. The dielectric constant of the insulating resin film at a frequency of 1 GHz was measured using a vector network analyzer (Anritsu MS46122B+040+002) by the cavity resonator perturbation method. Measurement of the dielectric properties at 1 GHz was performed in accordance with ASTM D2520, except that the cavity resonator was changed to a 1 GHz cavity resonator (Keycom model for use around 1 GHz). The dielectric constant was measured in an environment of temperature: 23°C ± 1°C, humidity: 50% ± 5%.

[0140] The dielectric constant of the insulating resin film at a frequency of 28 GHz was measured using a vector network analyzer with the Fabry-Perot method, a type of open-type resonator method. The resonator used was an open-type resonator (Fabry-Perot resonator manufactured by Keycom). The dielectric constant was measured in an environment of temperature: 23°C ± 1°C, humidity: 50% ± 5%.

[0141] ·Mechanical properties of insulating resin film The mechanical properties of the insulating resin film were evaluated in terms of tensile strength, elongation at break, and tensile modulus. Specifically, the tensile strength was measured in accordance with JIS K7127 at an environment of 23°C and 50% RH at a pulling rate of 50 mm / min in the machine direction (MD) and the transverse direction (TD), and the maximum strength was measured as the tensile strength.

[0142] ·Slipperiness of insulating resin film The slipperiness of the insulating resin film was evaluated using μs and μk. These μs and μk were measured in accordance with JIS K7125-1999. Specifically, a surface property measuring instrument (HEDON-14, manufactured by Shinto Scientific Co., Ltd.) was used to measure under the conditions of 23°C and 50% RH, a test speed of 100 mm / min, a load of 200 g, and a contact area MD: 63.5 mm × TD: 63.5 mm. Under these conditions, the cooling roll surface of the insulating resin film was fixed to the moving table, and the pressure roll surface of the insulating resin film was fixed to the flat indenter, and a load of 200 g was applied, and μs and μk were measured at a test speed of 100 mm / min.

[0143] ·Heat resistance of insulating resin film The heat resistance of the insulating resin film was evaluated by the storage modulus (E') at 260°C. The storage modulus of this insulating resin film was measured in the MD and TD of the insulating resin film. Specifically, when measuring the storage modulus of the insulating resin film in the MD, the insulating resin film was cut into a size of MD: 60 mm × TD: 6 mm, and when measuring the storage modulus of the insulating resin film in the TD, the insulating resin film was cut into a size of MD: 6 mm × TD: 60 mm and measured.

[0144] The storage modulus was measured in tension mode using a viscoelasticity spectrometer (TS Instruments Japan, product name: RSA-G2) under the following conditions: frequency 1 Hz, strain 0.1%, heating rate 3°C / min, measurement temperature range -60°C to 360°C, and check distance 21 mm, and the storage modulus at 260°C was calculated.

[0145] -Water absorption rate of insulating resin film The water absorption rate of the insulating resin film was measured in accordance with JIS K7209 Method A. Specifically, the insulating resin film was cut into a size of MD: 6.1 cm × TD: 6.1 cm, and immersed in water at 23°C for 14 days, and the water absorption rate was calculated from the rate of change in mass before and after immersion.

[0146] · Wrinkles that occur when insulating resin film is wound up during production During the production of the insulating resin film, the insulating resin film was wound up to determine whether or not wrinkles occurred. After 100 m of the film was wound up, the film was visually inspected and marked with either ◯ or ×. ◯ indicates no wrinkles, and × indicates wrinkles.

[0147] Fisheyes that occur during the manufacturing of insulating resin films Fisheyes that occur during the production of the insulating resin film were observed by visual inspection under transmitted light after cutting a 5m length of the insulating resin film in MD, and marked with either "good" or "bad." 〇:10mm 2 If no fisheyes of this size or larger have occurred ×:10mm 2 If a fisheye of this size occurs

[0148] Example 2 The process was basically the same as in Example 1, except that the molding materials used were the crystalline TPI resin used in Example 1 and the PFA resin, a fluororesin with melt fluidity, which was changed from Neoflon PFA AP-201 to Neoflon PFA AP-210 (product name, manufactured by Daikin Industries, Ltd.; hereinafter, abbreviated as AP-210) and the PFA resin was weighed out so that it was 5 parts by weight per 100 parts by mass of the crystalline TPI resin. The two resins were then placed in a mixer and mixed at room temperature for 1 hour to prepare a stirred mixture.

[0149] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and the measurement found it to be 350°C.

[0150] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 355°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are summarized in Table 1.

[0151] Example 3 The process was basically the same as in Example 2, except that the molding materials used were the crystalline TPI resin used in Example 1 and the PFA resin, a fluororesin with melt flowability, AP-210, used in Example 2. 20 parts by weight of PFA resin was weighed out for 100 parts by mass of the crystalline TPI resin, and the two resins were then placed in a mixer and mixed at room temperature for 1 hour to prepare a stirred mixture.

[0152] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 345°C.

[0153] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 352°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are summarized in Table 1.

[0154] Example 4 The process was basically the same as in Example 1, except that the molding materials used were the crystalline TPI resin used in Example 1 and the PFA resin, a fluororesin with melt flowability, changed from Neoflon PFA AP-201 to Neoflon PFA AP-230 (product name, manufactured by Daikin Industries, Ltd.; hereinafter, abbreviated as AP-230), and the PFA resin was weighed out so that it was 10 parts by weight per 100 parts by mass of the crystalline TPI resin. The two resins were then placed in a mixer and mixed by stirring at room temperature for 1 hour to prepare a stirred mixture.

[0155] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 344°C.

[0156] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 356°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are summarized in Table 1.

[0157] [Table 1]

[0158] Example 5 The process was basically the same as in Example 1, except that the molding materials used in Example 1, the crystalline TPI resin and the PFA resin, a fluororesin with melt flowability, were changed from Neoflon PFA AP-201 to Neoflon PFA powder paint ACX31 (product name manufactured by Daikin Industries, Ltd. (hereinafter abbreviated as ACX31)).

[0159] 100 parts by mass of this crystalline TPI resin was fed into the raw material inlet of the vented rotating twin-screw extruder used in Example 1 and melted. 15 parts by weight of ACX31 was fed into the side feeder on the die side of the co-rotating twin-screw extruder so as to be melt-kneaded and dispersed relative to 100 parts by mass of the crystalline TPI resin. The molten mixture was extruded into a rod shape from the die at the tip of the co-rotating twin-screw extruder, cooled with water, and cut with a pelletizer to prepare a pellet-shaped molding material.

[0160] The stirred mixture was melt-kneaded to prepare a molding material under conditions of a cylinder temperature of 300 to 350°C and a die temperature of 350°C, with the vent on the raw material inlet side of the co-rotating twin-screw extruder open and the vent on the die side degassed under reduced pressure. The temperature during melt-kneading was measured as the temperature of the molten molding material immediately after extrusion from the die, and was found to be 343°C.

[0161] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 2.

[0162] Example 6 The process was basically the same as in Example 1, except that the molding materials used were the crystalline TPI resin used in Example 1 and the PFA resin, a fluororesin with melt flowability, which was changed from Neoflon PFA AP-201 to Fluon PFA P-63P (a product name manufactured by AGC Corporation (hereinafter abbreviated as P-63P)), and the PFA resin was weighed out so that it was 25 parts by weight per 100 parts by mass of the crystalline TPI resin.The two resins were then charged into a mixer and mixed by stirring at room temperature for 1 hour to prepare a stirred mixture.

[0163] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 344°C.

[0164] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 355°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 2.

[0165] Example 7 The process was basically the same as in Example 1, except that the molding material was changed from the crystalline TPI resin used in Example 1 to FEP resin instead of PFA resin as the melt-flowable fluororesin. The FEP resin used was Neoflon FEP NP-20 (manufactured by Daikin Industries, Ltd., product name (hereinafter abbreviated as NP-20)). The FEP resin was weighed out so that it was 10 parts by mass per 100 parts by mass of the crystalline TPI resin. The two resins were then placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0166] A molding material was prepared in the same manner as in Example 1, except that PFA AP-201 was replaced with Neoflon PFA AP-230 (a product name manufactured by Daikin Industries, Ltd. (hereinafter abbreviated as AP-230)), and the PFA resin was weighed out so that it was 10 parts by weight per 100 parts by mass of the crystalline TPI resin.The two resins were then placed in a mixer and mixed by stirring at room temperature for 1 hour to prepare a stirred mixture.

[0167] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 342°C.

[0168] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 353°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 2.

[0169] Example 8 This example was basically the same as Example 1, except that the melt-flowable fluororesin used as the molding material was changed from PFA resin to a commercially available adhesive fluororesin. The adhesive fluororesin used was EA-2000 (product name, manufactured by AGC Corporation; hereafter abbreviated as "EA-2000"). The adhesive fluororesin was weighed out so that it was 10 parts by mass per 100 parts by mass of the crystalline TPI resin. The two resins were then placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0170] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 360°C.

[0171] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 353°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 2.

[0172] [Table 2]

[0173] Example 9 The procedure was basically the same as in Example 1, except that the molding material used was the crystalline TPI resin used in Example 1, and the melt-flowable fluororesin used was EA-2000 from Example 8. The adhesive fluororesin was weighed out so that it was 20 parts by mass per 100 parts by mass of the crystalline TPI resin, and then the two resins were placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0174] Thereafter, a molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was 360° C. The temperature of the molten molding material was measured by measuring the resin temperature at the die inlet, which was 361° C.

[0175] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 3.

[0176] Example 10 The procedure was basically the same as in Example 1, but the molding material used was the crystalline TPI resin used in Example 1, and the melt-flowable fluororesin used was EA-2000, used in Example 8. The adhesive fluororesin was weighed out so that it was 40 parts by mass per 100 parts by mass of the crystalline TPI resin, and the two resins were then placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0177] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 360°C.

[0178] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 353°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 3.

[0179] Example 11 The process was basically the same as in Example 1, except that the molding material used was the crystalline TPI resin used in Example 1, and the melt-flowable fluororesin was EA-2000 (product name, manufactured by AGC Corporation; hereinafter abbreviated as "EA-2000"). The adhesive fluororesin was weighed out so that it was 90 parts by mass per 100 parts by mass of the crystalline TPI resin, and the two resins were then placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0180] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 360°C.

[0181] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 353°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 3.

[0182] [Table 3]

[0183] Comparative Example 1 First, a molding material was prepared from a crystalline TPI resin and a fluororesin with melt fluidity. The molding material was prepared by preparing 100 parts by mass of the crystalline TPI resin used in Example 1, and weighing out 0.3 parts by mass of AP-201, the fluororesin with melt fluidity used in Example 1, per 100 parts by mass of this crystalline TPI resin. The two resins were then placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0184] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 350°C.

[0185] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 355°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated. The results are summarized in Table 4.

[0186] Comparative Example 2 First, a molding material was prepared from a crystalline TPI resin and a fluororesin with melt fluidity. The molding material consisted of 100 parts by mass of the crystalline TPI resin used in Example 1, and 0.3 parts by mass of EA-2000, the fluororesin with melt fluidity used in Example 8, weighed out relative to 100 parts by mass of the crystalline TPI resin. The two resins were then placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0187] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and the measurement was 349°C.

[0188] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 355°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated. The results are summarized in Table 4.

[0189] Comparative Example 3 First, a molding material was prepared from a crystalline TPI resin and a fluororesin having melt fluidity. The molding material was prepared by preparing 100 parts by mass of the crystalline TPI resin used in Example 1, and weighing out 120 parts by mass of AP-210, the fluororesin having melt fluidity used in Example 2, for each 100 parts by mass of this crystalline TPI resin. The two resins were then placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0190] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 347°C.

[0191] The molding material was then placed in a dehumidified hot air dryer heated to 160°C and dried for 12 hours. The dried molding material was then placed in a 40mm diameter single-screw extruder equipped with a 900mm wide T-die and melt-mixed. The melt-mixed molding material was continuously extruded through the T-die of the single-screw extruder to attempt extrusion molding of an insulating film. However, the molding material slipped within the melt extruder, making it impossible to feed the molding material into the melt extruder. As a result, an insulating resin film could not be produced. Therefore, the insulating film was not evaluated.

[0192] Comparative Example 4 First, a molding material was prepared from a crystalline TPI resin and a fluororesin having melt fluidity. The molding material was prepared by preparing 100 parts by mass of the crystalline TPI resin used in Example 1 and weighing out 120 parts by mass of EA-2000, the fluororesin having melt fluidity used in Example 8, per 100 parts by mass of this crystalline TPI resin. The two resins were then placed in a mixer and stirred at room temperature for 1 hour to prepare a stirred mixture.

[0193] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 346°C.

[0194] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 355°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated. The results are summarized in Table 4.

[0195] [Table 4]

[0196] Comparative Example 5 First, a molding material was prepared from a crystalline TPI resin and a fluororesin with no melt flowability. A commercially available PTFE resin was used as a fluororesin with no melt flowability. For the molding material, 100 parts by mass of the crystalline TPI resin used in Example 1 was prepared. This 100 parts by mass crystalline TPI resin was introduced into the raw material inlet of a vented co-rotating twin-screw extruder and melted. Fluon PTFE lubricant L1743JE (manufactured by AGC Corporation; product name, hereinafter abbreviated as "L173JE") was supplied to the side feeder on the die side of the co-rotating twin-screw extruder in an amount of 10 parts by mass per 100 parts by mass of the crystalline TPI resin, melt-kneaded and dispersed. The molten mixture was extruded into a rod shape from the die at the tip of the co-rotating twin-screw extruder, cooled with water, and cut with a pelletizer to prepare a pellet-shaped molding material.

[0197] The molding material was prepared in the same manner as in Example 1, but the temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, which was found to be 393°C.

[0198] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 355°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated. The results are summarized in Table 5.

[0199] Comparative Example 6 The TPI resin was changed from a crystalline TPI resin to a polyetherimide resin (a commercially available amorphous thermoplastic polyimide resin (hereinafter abbreviated as "amorphous TPI resin") [polycondensation product of 4,4'-[isopropylidenebis(p-phenyloxy)diphthalic dianhydride and m-phenylenediamine, manufactured by SABIC, product name: ULTEM 1010-1000-NB [manufactured by SABIC: product name, (hereinafter abbreviated as "1010")]].

[0200] 100 parts by mass of 1010 was prepared and placed in a dehumidified hot air dryer heated to 160°C and dried for 12 hours or more. The apparent shear viscosity of 1010 at 350°C was measured in the same manner as for the crystalline TPI resin in Example 1. 10 parts by mass of AP-210, which was used in Example 2, was also prepared as a fluororesin having melt fluidity. After preparing these, the two resins were then placed in a mixer and stirred and mixed to prepare a stirred mixture.

[0201] After the stirred mixture was prepared, it was fed into the same co-rotating twin-screw extruder as used in Example 1, and a molding material was prepared in the same manner as in Example 1. The kneading temperature was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 348°C.

[0202] The molding material was then placed in a dehumidifying hot air dryer heated to 160°C and dried for 12 hours, and the dried molding material was extruded into a strip of insulating resin film in the same manner as in Example 1. The moisture content of the molding material was 300 ppm or less. The temperature of the molten molding material was measured by measuring the resin temperature at the entrance of a T-die, and was found to be 361°C. After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 5.

[0203] Comparative Example 7 The thermoplastic polyimide resin was changed from a crystalline thermoplastic polyimide resin to a commercially available amorphous thermoplastic polyimide resin, polyetherimide resin [a polycondensate of 4,4'-[isopropylidenebis(p-phenyloxy)diphthalic dianhydride] and p-phenylenediamine, manufactured by SABIC, product name: ULTEM CRS5001-1000-NB (hereinafter abbreviated as "CRS5001")].

[0204] 100 parts by mass of CRS5001 was prepared and dried for 12 hours in a dehumidifying dryer heated to 160°C. The apparent shear viscosity of 5001 at 350°C was measured in the same manner as for the crystalline thermoplastic polyimide resin in Example 1. 10 parts by mass of EA-2000, which was used in Example 8, was prepared as a fluororesin having melt fluidity. After preparing these, the two resins were then charged into a mixer and mixed by stirring to prepare a stirred mixture.

[0205] Once the stirred mixture was prepared, it was fed into the co-rotating twin-screw extruder used in Example 1, and a molding material was prepared in the same manner as in Example 1. The stirred mixture was melt-kneaded under conditions of a cylinder temperature of 200 to 360°C and a die temperature of 360°C to prepare a molding material. The temperature during melt-kneading was measured by measuring the temperature of the molten molding material immediately after extrusion from the die, and was found to be 364°C.

[0206] The molding material was then placed in a dehumidifying dryer heated to 160°C and dried for 12 hours or more. The dried molding material was then placed in the single-screw extruder equipped with a 900 mm wide T-die used in Example 1 and melt-kneaded. This melt-kneaded molding material was continuously extruded through the T-die to extrude an insulating resin film into a strip shape. The same single-screw extruder as in Example 1 was used. The temperature of this single-screw extruder was adjusted to 350 to 365°C, the temperature of the T-die to 365°C, and the temperature of the connecting pipe connecting the single-screw extruder and the T-die to 365°C. The temperature of the molten molding material was measured by measuring the resin temperature at the inlet of the T-die, and was found to be 372°C.

[0207] After producing the insulating resin film, the apparent shear viscosity of the melt-flowable fluororesin, the film thickness, relative crystallinity, insulating properties, mechanical properties, slipperiness, heat resistance of the insulating resin film, the occurrence of wrinkles when the produced insulating resin film was wound up, and the presence or absence of fisheyes were evaluated, and the results are shown in Table 5.

[0208] [Table 5]

[0209] 〔evaluation〕 Compared to the insulating resin films of the comparative examples, the insulating resin films of the examples have a relative dielectric constant of 2.4 to 2.8 at 1 GHz and a relative dielectric constant of 2.5 to 2.8 at 28 GHz, which suggests that they provide sufficient insulation. Furthermore, the tensile modulus is in the range of 1200 MPa to 2700 MPa, which suggests that they provide excellent adhesion to insulating materials. The maximum tensile strength is 56.4 MPa or more, and the tensile elongation at break is 127%, which suggests that they provide sufficient durability.

[0210] The water absorption rate of the insulating resin film 1 is preferably less than 1.0% at a temperature of 23°C. However, since the water absorption rate at 23°C was 0.8% or less, it is believed that high insulating properties can be maintained even in a high temperature and humidity environment. The storage modulus of the insulating resin film at 260°C was 1×10 7 Since it has a thermal resistance of 100 Pa or more, it can be expected to have high heat resistance. Therefore, it can also be used as an insulating resin film with a heat resistance classification of Class H.

[0211] In contrast, the insulating resin films of Comparative Examples 1 and 2, which contained 0.5 parts by mass or less of a fluid fluororesin, exhibited a high dielectric constant exceeding 2.8. This raised doubts about the insulating properties of the insulating resin films. Furthermore, since the water absorption rate was 1.0%, it is presumed that maintaining insulating properties in a high-temperature, humid environment would be difficult. Comparative Example 3 contained 110 parts by mass of PFA resin as a fluid fluororesin, so the molding material consisting of the molten crystalline thermoplastic polyimide resin and the fluororesin with melt fluidity slid within the melt extrusion molding machine, making it impossible to feed the molding material into the melt extrusion molding machine. As a result, it was impossible to mold or evaluate an insulating resin film.

[0212] The insulating resin film of Comparative Example 4 contained 120 parts by mass of a fluid fluororesin, so the tensile elongation at break was less than 100%, raising doubts about its toughness. Therefore, it is presumed that there is a high risk of breakage when the insulating resin film is wound. Furthermore, in Comparative Example 5, a non-fluid fluororesin was used as the fluororesin, which caused fisheyes to form in the insulating resin film, resulting in poor appearance of the insulating resin film. Additionally, the tensile elongation at break was less than 100%, raising doubts about its toughness. Therefore, it is presumed that there is a high risk of breakage when the insulating resin film is wound.

[0213] In Comparative Examples 6 and 7, amorphous thermoplastic polyimide resin was used, so no melting peak was observed, and the storage modulus at 260°C was 1 × 10 4 Pa or less, causing problems with heat resistance. [Industrial Applicability]

[0214] The insulating resin sheet and the method for producing the same according to the present invention are used in the fields of electricity, electronics, machinery, chemistry, semiconductors, and the like. [Explanation of symbols]

[0215] 1 Molding material 2. Insulating resin film 3 Nonwoven fabric (fiber sheet) 4 Adhesive layer 10. Melt extrusion molding machine 13 T Dice (Dice) 16 Crimping roll 17 Cooling roll 18 Winder 19 Winding tube

Claims

1. An insulating resin sheet comprising 100 parts by mass of a crystalline thermoplastic polyimide resin having a melting point of 300°C or higher and 10 parts by mass or more and 100 parts by mass or less of an adhesive fluororesin having melt flowability, the insulating resin sheet having a relative crystallinity of 95% or more and 100% or less, a relative dielectric constant at a frequency of 1 GHz of 2.4 or more and 2.8 or less when measured by a cavity resonator perturbation method, and a relative dielectric constant at a frequency of 28 GHz of 2.5 or more and 2.8 or less when measured by a Fabry-Perot method, The adhesive fluororesin contains a repeating unit (a) based on tetrafluoroethylene and / or chlorotrifluoroethylene, a repeating unit (b) based on a cyclic hydrocarbon monomer having a dicarboxylic anhydride group and a polymerizable unsaturated group in the ring, and a repeating unit (c) based on another monomer (however, if the repeating unit (a) or (b) overlaps with the repeating unit (a), this monomer is excluded), and is a fluororesin having a melting point of 150°C or higher and 320°C or lower.

2. 2. The insulating resin sheet according to claim 1, wherein the fiber sheets are laminated and integrated.

3. 3. The insulating resin sheet according to claim 1, wherein the maximum tensile strength is 50 MPa or more and 500 MPa or less when measured in accordance with JIS K 7127, and the tensile elongation at break is 100% or more and 500% or less when measured in accordance with JIS K 7127.

4. 4. The insulating resin sheet according to claim 1, 2, or 3, wherein the crystalline thermoplastic polyimide resin comprises a tetracarboxylic acid component and a diamine component, and more than 50 mol% of the tetracarboxylic acid component is pyromellitic acid, and more than 50 mol% of the diamine component is an aliphatic diamine.

5. A method for producing an insulating resin sheet having a relative crystallinity of 95% or more and 100% or less according to any one of claims 1 to 4, comprising: A method for producing an insulating resin sheet, comprising melt-kneading a molding material containing at least 100 parts by mass of a crystalline thermoplastic polyimide resin having a melting point of 300°C or higher and 10 to 100 parts by mass of an adhesive fluororesin having melt flowability, extruding the molding material through a die into an insulating resin sheet, and cooling and winding up the insulating resin sheet.

Images