Polyimide resin composition, polyimide varnish, and polyimide film

Abstract

A polyimide resin composition comprising: a polyimide resin (X) containing repeating units of formula (1) and formula (2); and a fluoropolymer (Y). (In formula (1), R...) 1 ~R 4 Each is independently a monovalent aliphatic group or a monovalent aromatic group, Z 1 and Z 2 Each is independently a divalent aliphatic group or a divalent aromatic group, where r is a positive integer, and R 5 It is a tetravalent alicyclic group with 4 to 39 carbon atoms. In formula (2), R 6 The group is a tetravalent alicyclic group having 4 to 39 carbon atoms, and Φ is a divalent aliphatic group, alicyclic group, aromatic group, or a combination thereof having a total of 2 to 39 carbon atoms. As a bonding group, it may optionally have at least one group selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-.

Description

Technical Field

[0001] This invention relates to polyimide resin compositions, polyimide varnishes, and polyimide films. Background Technology

[0002] Polyimide resins possess excellent mechanical properties and heat resistance, and therefore their various applications in electrical / electronic components and other fields are being researched. For example, there is a desire to replace glass substrates used in image display devices such as liquid crystal displays and OLED displays with polyimide film substrates, and to develop polyimide resins that meet the performance requirements as optical materials.

[0003] For example, Patent Document 1 discloses a polyimide copolymer obtained by reacting an acid dianhydride formed from hexahydropyromellitic anhydride and aromatic acid dianhydride with a diamine having polycyclic aromatic groups, siloxane groups, or other organic groups, for use as a peripheral component of an optical part or optical element.

[0004] Such polyimide films are typically manufactured by applying a varnish containing polyimide and solvent to a smooth metal strip or similar material and then drying and peeling it off.

[0005] Poor peelability can lead to uneven film thickness or scratches on the film surface. Therefore, research is underway to improve peelability.

[0006] For example, Patent Document 2 discloses a method for manufacturing an aromatic polyimide film by casting an aromatic polyamic acid solution containing a specific phosphate ester or the like onto a substrate into a film shape and then heating and post-heating it, with the aim of making it easy to peel the self-supporting film off the substrate.

[0007] In addition, Patent Document 3 discloses a manufacturing method for producing an extremely thin polyimide film, which includes a process of coating a polyimide resin precursor solution containing a release agent onto a substrate, a drying process, a thermosetting process, and a peeling process.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2017-222745

[0011] Patent Document 2: Japanese Patent Application Publication No. 60-244507

[0012] Patent Document 3: Japanese Patent Application Publication No. 2009-226632 Summary of the Invention

[0013] The problem the invention aims to solve

[0014] As mentioned earlier, while polyimide films can be peeled from smooth supports such as metal strips, slight breakage during peeling can be problematic in image display devices requiring high transparency and smoothness. Specifically, during film forming, the peelability of flexible polyimide resins with softness and low elastic modulus used in flexible devices tends to deteriorate from supports such as strips, thus requiring particularly high peelability.

[0015] In the aforementioned patent documents 2 and 3, release agents are used to improve peelability. However, due to their reactivity with the resin, problems such as a decrease in the molecular weight of the resin may occur, especially in high temperature and high humidity environments.

[0016] Therefore, there is a need for a polyimide resin composition that possesses the high colorless transparency required for optical materials, even when using additives such as release agents.

[0017] Therefore, the objective of this invention is to provide a polyimide resin composition that can form a film with excellent peelability from a support such as a tape, suppressed molecular weight reduction under high temperature and high humidity conditions, and excellent colorless transparency.

[0018] Solution for solving the problem

[0019] The inventors discovered that a composition containing a polyimide resin comprising specific repeating units and a fluoropolymer can solve the above-mentioned problems, and thus completed the invention.

[0020] That is, the present invention relates to the following [1] to

[14] . [1]

[0022] A polyimide resin composition comprising: a polyimide resin (X) containing repeating units of formula (1) and formula (2) below, and a fluoropolymer (Y).

[0023]

[0024] (In equation (1), R) 1 ~R 4 Each is independently a monovalent aliphatic group or a monovalent aromatic group, Z 1 and Z 2 Each is independently a divalent aliphatic group or a divalent aromatic group, where r is a positive integer, and R 5 It is a tetravalent alicyclic group with 4 to 39 carbon atoms.

[0025] In equation (2), R 6Φ is a tetravalent alicyclic group having 4 to 39 carbon atoms, and Φ is a divalent aliphatic group, alicyclic group, aromatic group, or a combination thereof having a total of 2 to 39 carbon atoms. As a bonding group, Φ may optionally have at least one group selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-. [2]

[0027] According to the polyimide resin composition described in [1], the content of fluoropolymer (Y) is 0.01 to 1 part by mass relative to 100 parts by mass of polyimide resin (X). [3]

[0029] According to the polyimide resin composition of [1] or [2], wherein the fluoropolymer (Y) is a fluoroacrylate polymer. [4]

[0031] The polyimide resin composition according to any one of [1] to [3], wherein the ratio of repeating units of the aforementioned formula (1) in the polyimide resin (X) is 10 to 50 mol%. [5]

[0033] The polyimide resin composition according to any one of [1] to [4], wherein the repeating unit shown in the aforementioned formula (1) is composed of a structural unit (A-1) derived from the compound shown in formula (a-1) and a structural unit (B-1) derived from the compound shown in formula (b-1).

[0034]

[0035] (In equation (b-1), R) 1 ~R 4 Each is independently a monovalent aliphatic group or a monovalent aromatic group, Z 1 and Z 2 Each group can be independently a divalent aliphatic group or a divalent aromatic group, where r is a positive integer. [6]

[0037] The polyimide resin composition according to any one of [1] to [5], wherein the repeating unit shown in the aforementioned formula (2) is composed of structural unit (A-1) and structural unit (B-2) derived from the compound shown in formula (a-1), said structural unit (B-2) being selected from at least one of the group consisting of structural unit (B-2-1) derived from the compound shown in formula (b-2-1), structural unit (B-2-2) derived from the compound shown in formula (b-2-2), and structural unit (B-2-3) derived from the compound shown in formula (b-2-3).

[0038] [7]

[0040] According to the polyimide resin composition of [5] or [6], wherein the ratio of structural units (A-1) derived from tetracarboxylic acid dianhydride constituting the polyimide resin (X) is 50 mol% or more. [8]

[0042] The polyimide resin composition according to any one of [5] to [7], wherein the ratio of structural units (B-1) in the diamine-derived structural units constituting the polyimide resin (X) is 10 to 50 mol%. [9]

[0044] The polyimide resin composition according to any one of [6] to [8], wherein the ratio of structural units (B-2) in the diamine-derived structural units constituting the polyimide resin (X) is 50 to 90 mol%.

[10]

[0046] The polyimide resin composition according to any one of [6] to [9], wherein the structural unit (B-2) is the structural unit (B-2-1).

[11]

[0048] The polyimide resin composition according to any one of [6] to [9], wherein the structural unit (B-2) is a structural unit (B-2-2).

[12]

[0050] The polyimide resin composition according to any one of [6] to [9], wherein the structural unit (B-2) is a structural unit (B-2-3).

[13]

[0052] A polyimide varnish, which is formed by dissolving the polyimide resin composition described in any one of [1] to

[12] in an organic solvent.

[14]

[0054] A polyimide film comprising any one of the polyimide resin compositions described in [1] to

[12] .

[0055] The effects of the invention

[0056] The present invention provides a polyimide resin composition capable of forming a film with excellent peelability from a support such as a tape, suppressed molecular weight reduction under high temperature and high humidity conditions, and excellent colorless transparency. Detailed Implementation

[0057] [Polyimide resin composition]

[0058] The polyimide resin composition of the present invention comprises: a polyimide resin (X) containing repeating units shown in formula (1) and repeating units shown in formula (2) below, and a fluoropolymer (Y).

[0059]

[0060] (In equation (1), R) 1 ~R 4 Each is independently a monovalent aliphatic group or a monovalent aromatic group, Z 1 and Z 2 Each is independently a divalent aliphatic group or a divalent aromatic group, where r is a positive integer, and R 5 It is a tetravalent alicyclic group with 4 to 39 carbon atoms.

[0061] In equation (2), R 6 Φ is a tetravalent alicyclic group having 4 to 39 carbon atoms, and Φ is a divalent aliphatic group, alicyclic group, aromatic group, or a combination thereof having a total of 2 to 39 carbon atoms. As a bonding group, Φ may optionally have at least one group selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-.

[0062] <Polyimide Resin (X)>

[0063] The polyimide resin (X) contained in the polyimide resin composition of the present invention comprises repeating units shown in formula (1) and repeating units shown in formula (2).

[0064]

[0065] (In equation (1), R) 1 ~R 4 Each is independently a monovalent aliphatic group or a monovalent aromatic group, Z 1 and Z 2 Each is independently a divalent aliphatic group or a divalent aromatic group, where r is a positive integer, and R 5 It is a tetravalent alicyclic group with 4 to 39 carbon atoms.

[0066] In equation (2), R 6 Φ is a tetravalent alicyclic group having 4 to 39 carbon atoms, and Φ is a divalent aliphatic group, alicyclic group, aromatic group, or a combination thereof having a total of 2 to 39 carbon atoms. As a bonding group, Φ may optionally have at least one group selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-.

[0067] (The repeating unit shown in equation (1))

[0068] From the viewpoint of colorless transparency and softness, polyimide resin (X) contains repeating units as shown in the aforementioned formula (1).

[0069] In the aforementioned equation (1), R 1 R 2 R 3 and R 4 Each group is independently a monovalent aliphatic group or a monovalent aromatic group, wherein at least a portion of the hydrogen atoms in these groups are optionally replaced by fluorine atoms. Examples of monovalent aliphatic groups include monovalent saturated hydrocarbon groups, monovalent unsaturated hydrocarbon groups, and monovalent hydroxyl groups. Examples of monovalent saturated hydrocarbon groups include alkyl groups having 1 to 22 carbon atoms, such as methyl, ethyl, and propyl. Examples of monovalent unsaturated hydrocarbon groups include alkenyl groups having 2 to 22 carbon atoms, such as vinyl and propenyl. Examples of monovalent hydroxyl groups include alkoxy groups having 1 to 22 carbon atoms, such as monovalent groups formed by bonding oxygen atoms to the aforementioned alkyl groups. Examples of monovalent aromatic groups include aryl groups having 6 to 24 carbon atoms, aralkyl groups having 7 to 24 carbon atoms, and aryloxy groups having 6 to 24 carbon atoms, such as phenyl and phenoxy groups. As R 1 R 2 R 3 and R 4 Methyl or phenyl is particularly preferred.

[0070] Z 1 and Z 2 Each group is independently a divalent aliphatic group or a divalent aromatic group, wherein at least a portion of the hydrogen atoms in these groups are optionally substituted with fluorine atoms. Examples of divalent aliphatic groups include divalent saturated hydrocarbon groups or divalent unsaturated hydrocarbon groups. Examples of divalent saturated hydrocarbon groups include alkylene groups having 1 to 22 carbon atoms, such as methylene, ethylene, propylene, trimethylene, tetramethylene, hexamethylene, octamethylene, decamethylene, dodecamethylene, etc. Examples of divalent unsaturated hydrocarbon groups include unsaturated hydrocarbon groups having 2 to 22 carbon atoms, such as vinyl, propenyl, and alkylene groups terminally having unsaturated double bonds. Examples of divalent aromatic groups include aryl, arylalkyl, arylalkyl, and aryloxy groups having 6 to 24 carbon atoms. In these groups, at least a portion of the hydrogen atoms constituting the aromatic ring are optionally substituted with alkyl groups. 1 and Z 2Specific examples of arylene groups having 6 to 24 carbon atoms include o-phenylene, m-phenylene, p-phenylene, 4,4'-biphenylene, and 2,6-naphthylene. Specific examples of arylene alkyl groups having 7 to 24 carbon atoms include benzylene and phenylethylene. Specific examples of arylene oxy groups having 6 to 24 carbon atoms include divalent groups formed by bonding an oxygen atom to the aforementioned arylene groups. As Z 1 and Z 2 Preferred compounds include propylene, trimethylene, tetramethylene, p-phenylene, and benzylene, with trimethylene, tetramethylene, and p-phenylene being more preferred.

[0071] Additionally, r is a positive integer, preferably an integer between 2 and 50. When r is greater than 2, multiple R... 1 and R 2 They can be the same or different.

[0072] R 5 It is a tetravalent alicyclic group with 4 to 39 carbon atoms, preferably a tetravalent alicyclic group with 4 to 8 carbon atoms, more preferably a tetravalent alicyclic group with 4 to 6 carbon atoms, and even more preferably a tetravalent alicyclic group with 6 carbon atoms.

[0073] The ratio of the repeating units shown in the aforementioned formula (1) in the polyimide resin (X) is preferably 10 to 50 mol%, more preferably 10 to 40 mol%, even more preferably 15 to 30 mol%, and particularly preferably 15 to 25 mol%.

[0074] As a polyimide resin (X), from the viewpoint of colorless transparency and softness, the repeating unit shown in the aforementioned formula (1) is preferably composed of a structural unit (A-1) derived from the compound shown in formula (a-1) below and a structural unit (B-1) derived from the compound shown in formula (b-1) below.

[0075]

[0076] (In equation (b-1), R) 1 ~R 4 Each is independently a monovalent aliphatic group or a monovalent aromatic group, Z 1 and Z 2 Each group can be independently a divalent aliphatic group or a divalent aromatic group, where r is a positive integer.

[0077] The compound shown in formula (a-1) is 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride.

[0078] By incorporating structural units (A-1) into the polyimide resin (X), the colorless transparency of the film is improved.

[0079] R in equation (b-1) 1 ~R 4 Z1 Z 2 r and r are respectively related to R in the aforementioned equation (1) 1 ~R 4 Z 1 Z 2 、r is synonymous.

[0080] Examples of compounds represented by formula (b-1) include 1,3-bis(3-aminopropyl)-1,1,2,2-tetramethyldisiloxane, 1,3-bis(3-aminobutyl)-1,1,2,2-tetramethyldisiloxane, 1,3-bis(4-aminophenoxy)tetramethyldisiloxane, 1,1,3,3-tetramethyl-1,3-bis(4-aminophenyl)disiloxane, 1,1,3,3-tetraphenoxy-1,3-bis(2-aminoethyl)disiloxane, and 1,1,3,3-tetraphenyl-1,3-bis( 2-Aminoethyl)disiloxane, 1,1,3,3-tetraphenyl-1,3-bis(3-aminopropyl)disiloxane, 1,1,3,3-tetramethyl-1,3-bis(2-aminoethyl)disiloxane, 1,1,3,3-tetramethyl-1,3-bis(3-aminopropyl)disiloxane, 1,1,3,3-tetramethyl-1,3-bis(4-aminobutyl)disiloxane, 1,3-dimethyl-1,3-dimethoxy-1,3-bis(4-aminobutyl)disiloxane, 1,1,3,3,5,5- Hexamethyl-1,5-bis(4-aminophenyl)trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethyl-1,5-bis(3-aminopropyl)trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis(4-aminobutyl)trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis(5-aminopentyl)trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis(2-aminoethyl)trisiloxane, 1, 1,5,5-Tetramethyl-3,3-dimethoxy-1,5-bis(4-aminobutyl)trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis(5-aminopentyl)trisiloxane, 1,1,3,3,5,5-hexamethyl-1,5-bis(3-aminopropyl)trisiloxane, 1,1,3,3,5,5-hexaethyl-1,5-bis(3-aminopropyl)trisiloxane, 1,1,3,3,5,5-hexapropyl-1,5-bis(3-aminopropyl)trisiloxane, etc. The compounds shown in formula (b-1) can be used alone or in combination of two or more.

[0081] Commercially available products of the compounds shown in formula (b-1) include “X-22-9409”, “X-22-1660B”, “X-22-161AS”, “X-22-161A”, and “X-22-161B” manufactured by Shin-Etsu Chemical Industry Co., Ltd.

[0082] By incorporating structural units (B-1) into the polyimide resin (X), the low elastic modulus of the film is achieved.

[0083] (The repeating unit shown in equation (2))

[0084] The polyimide resin (X) contains the repeating unit shown in the aforementioned formula (2).

[0085] In the aforementioned equation (2), R 6 It is a tetravalent alicyclic group with 4 to 39 carbon atoms, preferably a tetravalent alicyclic group with 4 to 8 carbon atoms, more preferably a tetravalent alicyclic group with 4 to 6 carbon atoms, and even more preferably a tetravalent alicyclic group with 6 carbon atoms.

[0086] Φ is a divalent aliphatic group, alicyclic group, aromatic group, or a combination thereof with a total number of carbons of 2 to 39, preferably a group having an aromatic group.

[0087] In addition, Φ is selected as a bonding group, having at least one of the following groups: -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O- and -S-. It is preferred to have -O- as the bonding group.

[0088] As a polyimide resin (X), from the viewpoint of colorless transparency, the repeating unit shown in the aforementioned formula (2) is preferably composed of structural units (A-1) and (B-2) derived from the compound shown in the aforementioned formula (a-1), wherein the structural unit (B-2) is selected from at least one of the group consisting of structural units (B-2-1) derived from the compound shown in the following formula (b-2-1), structural units (B-2-2) derived from the compound shown in the following formula (b-2-2), and structural units (B-2-3) derived from the compound shown in the following formula (b-2-3).

[0089]

[0090] The compound shown in formula (b-2-1) is 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane.

[0091] The compound shown in formula (b-2-2) is 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

[0092] The compound shown in formula (b-2-3) is 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine.

[0093] In this invention, by including structural unit (B-2) in the polyimide resin (X), the glass transition temperature of the film can be increased. In particular, structural unit (B-1) contributes to the low elastic modulus of the film, but on the other hand, it also lowers the glass transition temperature. Therefore, by including structural unit (B-2) in structural unit B, the decrease in glass transition temperature caused by structural unit (B-1) can be reduced, thereby controlling the glass transition temperature of the film. Furthermore, from the viewpoint of obtaining a film with excellent colorless transparency, it is also preferable that the polyimide resin (X) includes structural unit (B-2).

[0094] Structural unit (B-2) can be only structural unit (B-2-1), only structural unit (B-2-2), or only structural unit (B-2-3).

[0095] In addition, structural unit (B-2) can be a combination of structural unit (B-2-1) and structural unit (B-2-2), a combination of structural unit (B-2-2) and structural unit (B-2-3), or a combination of structural unit (B-2-1) and structural unit (B-2-3).

[0096] In addition, structural unit (B-2) can be a combination of structural unit (B-2-1), structural unit (B-2-2), and structural unit (B-2-3).

[0097] (Ratios of each structural unit and other structural units)

[0098] The proportion of structural unit (A-1) in the structural unit derived from tetracarboxylic dianhydride (hereinafter also referred to as "structural unit A") constituting the polyimide resin (X) is preferably 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more. There is no particular upper limit to the proportion of structural unit (A-1), i.e., it is 100 mol%. Structural unit A may also contain only structural unit (A-1).

[0099] Structural unit A may also contain structural units other than structural unit (A-1). There are no particular limitations on the tetracarboxylic dianhydrides that provide such structural units, and examples include aromatic tetracarboxylic dianhydrides such as pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride, and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride; alicyclic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride and norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic dianhydride (except for the compounds shown in formula (a-1)); and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride.

[0100] It should be noted that, in this specification, aromatic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride containing one or more alicyclic rings but not aromatic rings, and aliphatic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride containing neither aromatic rings nor alicyclic rings.

[0101] Structural unit A may contain one or more structural units other than structural unit (A-1).

[0102] In addition, as one type of polyimide resin (X), a polyimide resin in which structural unit A does not contain structural units derived from 9,9'-bis(3,4-dicarboxyphenyl)fluorene dihydride can be cited.

[0103] The ratio of structural units (B-1) in the diamine-derived structural units (hereinafter also referred to as "structural units B") constituting the polyimide resin (X) is preferably 10 to 50 mol%, more preferably 10 to 40 mol%, even more preferably 15 to 30 mol%, and particularly preferably 15 to 25 mol%.

[0104] The ratio of structural unit (B-2) in structural unit B is preferably 50-90 mol%, more preferably 60-90 mol%, even more preferably 70-85 mol%, and particularly preferably 75-85 mol%.

[0105] The total ratio of structural units (B-1) and (B-2) in structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 99 mol% or more. There is no particular upper limit to the total ratio of structural units (B-1) and (B-2), i.e., it is 100 mol%. Structural unit B may also consist only of structural units (B-1) and (B-2).

[0106] Structural unit B may also include structural units other than structural units (B-1) and (B-2). There are no particular limitations on the diamine providing such a structural unit; examples include 1,4-phenylenediamine, p-dimethylbenzylenediamine, 3,5-diaminobenzoic acid, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone, 4,4'-diaminobenzoylaniline, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis... Aromatic diamines such as (4-aminophenyl)terephthalamide, 4,4'-bis(4-aminophenoxy)biphenyl and 9,9-bis(4-aminophenyl)fluorene (excluding compounds shown in formula (b-1), (b-2-1), (b-2-2) and (b-2-3); alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine (excluding compounds shown in formula (b-1)).

[0107] It should be noted that, in this specification, aromatic diamines refer to diamines containing one or more aromatic rings, alicyclic diamines refer to diamines containing one or more alicyclic rings but not aromatic rings, and aliphatic diamines refer to diamines containing neither aromatic nor alicyclic rings.

[0108] Structural unit B may contain one or more structural units other than structural units (B-1) and (B-2).

[0109] (Properties of polyimide resin (X))

[0110] From the viewpoint of the mechanical strength of the obtained polyimide film, the number-average molecular weight of the polyimide resin (X) is preferably 5,000 to 100,000. It should be noted that the number-average molecular weight of the polyimide resin can be determined, for example, by conversion of the standard polymethyl methacrylate (PMMA) value based on gel filtration chromatography.

[0111] By using polyimide resin (X), a colorless and highly transparent film can be formed. The suitable physical properties of the film obtained by using polyimide resin (X) are as follows.

[0112] The tensile modulus of the polyimide resin (X) is preferably 2.1 GPa or less, more preferably 2.0 GPa or less, and even more preferably 1.8 GPa or less.

[0113] By setting the tensile modulus to this range, polyimide films with high flexibility, suitable for flexible displays, etc., can be obtained.

[0114] The tensile strength is preferably 40 MPa or more, more preferably 50 MPa or more, and even more preferably 60 MPa or more.

[0115] The tensile modulus and tensile strength are measured according to JIS K7127, for example, using a tensile testing machine such as the "Strograp HVG-1E" manufactured by Toyo Seiki Co., Ltd.

[0116] Regarding the total light transmittance, when forming a film with a thickness of 30 μm, it is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more.

[0117] Regarding haze, when forming a film with a thickness of 30 μm, it is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less.

[0118] For the yellow index (YI), when forming a film with a thickness of 30 μm, it is preferably 6.0 or less, more preferably 3.0 or less, and even more preferably 1.5 or less.

[0119] Total transmittance, haze, and yellowness index (YI) can be specifically determined by the methods described in the examples.

[0120] The absolute value of the thickness phase difference (Rth) is preferably 100 nm or less when forming a thin film with a thickness of 30 μm, more preferably 50 nm or less, and even more preferably 30 nm or less.

[0121] The glass transition temperature (Tg) is preferably 150–300°C, more preferably 150–280°C, and even more preferably 150–250°C.

[0122] (Manufacturing method of polyimide resin (X))

[0123] Polyimide resin (X) can be manufactured by reacting a tetracarboxylic acid component and a diamine component containing a compound providing a repeating unit as shown in formula (1) above, and a tetracarboxylic acid component and a diamine component containing a compound providing a repeating unit as shown in formula (2) above. Preferably, it is manufactured by reacting a tetracarboxylic acid component containing a compound providing a structural unit (A-1) with a diamine component containing a compound providing a structural unit (B-1) and a compound providing a structural unit (B-2).

[0124] Examples of compounds providing the structural unit (A-1) include those shown in formula (a-1), but are not limited thereto; derivatives thereof may also be provided within the range of compounds providing the same structural unit. Examples of such derivatives include tetracarboxylic acids (i.e., 1,2,4,5-cyclohexanetetracarboxylic acid) and alkyl esters of the tetracarboxylic acid corresponding to the tetracarboxylic acid dianhydride shown in formula (a-1). The compound shown in formula (a-1) (i.e., the dianhydride) is preferred as the compound providing the structural unit (A-1).

[0125] The tetracarboxylic acid component preferably comprises 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more of a compound providing the structural unit (A-1). There is no particular upper limit to the content of the compound providing the structural unit (A-1), i.e., it can be 100 mol%. The tetracarboxylic acid component may also comprise only the compound providing the structural unit (A-1).

[0126] The tetracarboxylic acid component may also include compounds other than those that provide the structural unit (A-1). Examples of such compounds include the aromatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, and aliphatic tetracarboxylic dianhydrides and their derivatives (tetracarboxylic acids, alkyl esters of tetracarboxylic acids, etc.).

[0127] The tetracarboxylic acid component may contain one or more compounds other than the compound that provides the structural unit (A-1).

[0128] Examples of compounds providing the structural unit (B-1) include those shown in formula (b-1), but are not limited thereto; derivatives thereof may also be provided within the range of compounds providing the same structural unit. Examples of such derivatives include diisocyanates corresponding to the diamine shown in formula (b-1). The compound shown in formula (b-1) (i.e., the diamine) is preferred as the compound providing the structural unit (B-1).

[0129] As the compound providing structural unit (B-2), at least one is selected from the group consisting of compounds providing structural unit (B-2-1), compounds providing structural unit (B-2-2), and compounds providing structural unit (B-2-3).

[0130] Examples of compounds providing structural unit (B-2-1), structural unit (B-2-2), and structural unit (B-2-3) include compounds represented by formula (b-2-1), (b-2-2), and (b-2-3), respectively, but are not limited thereto; derivatives thereof may also be provided within the scope of providing the same structural unit. Examples of such derivatives include diisocyanates corresponding to the diamines represented by the compound represented by formula (b-2-1), diisocyanates corresponding to the diamines represented by the compound represented by formula (b-2-2), and diisocyanates corresponding to the diamines represented by the compound represented by formula (b-2-3). As compounds providing structural unit (B-2-1), compounds providing structural unit (B-2-2), and compounds providing structural unit (B-2-3), the compounds represented by formula (b-2-1) (i.e., diamine), the compounds represented by formula (b-2-2) (i.e., diamine), and the compounds represented by formula (b-2-3) (i.e., diamine) are preferred, respectively.

[0131] As a compound providing structural unit (B-2), a compound providing structural unit (B-2-1) may be used, a compound providing structural unit (B-2-2) may be used, or a compound providing structural unit (B-2-3) may be used.

[0132] Alternatively, as a compound providing structural unit (B-2), a combination of a compound providing structural unit (B-2-1) and a compound providing structural unit (B-2-2) can be used, a combination of a compound providing structural unit (B-2-2) and a compound providing structural unit (B-2-3) can be used, or a combination of a compound providing structural unit (B-2-1) and a compound providing structural unit (B-2-3) can also be used.

[0133] In addition, as a compound providing structural unit (B-2), a combination of a compound providing structural unit (B-2-1), a compound providing structural unit (B-2-2), and a compound providing structural unit (B-2-3) may also be used.

[0134] The diamine component preferably comprises 10-50 mol%, more preferably 10-40 mol%, further preferably 15-30 mol%, and particularly preferably 15-25 mol% of a compound providing the structural unit (B-1).

[0135] The diamine component preferably comprises 50-90 mol%, more preferably 60-90 mol%, further preferably 70-85 mol%, and particularly preferably 75-85 mol% of a compound providing the structural unit (B-2).

[0136] The diamine component preferably comprises a total of 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the total content of the compounds providing structural units (B-1) and (B-2) is not particularly limited, i.e., it can be 100 mol%. The diamine component may also comprise only the compounds providing structural units (B-1) and (B-2).

[0137] The diamine component may also include compounds other than those providing structural unit (B-1) and those providing structural unit (B-2). Examples of such compounds include the aromatic diamines, alicyclic diamines, and aliphatic diamines and their derivatives (such as diisocyanates).

[0138] The diamine component may contain one or more compounds other than the compound providing structural unit (B-1) and the compound providing structural unit (B-2).

[0139] In this invention, the preferred ratio of tetracarboxylic acid component and diamine component used in the manufacture of polyimide resin (X) is 0.9 to 1.1 moles of diamine component relative to 1 mole of tetracarboxylic acid component.

[0140] In addition, in the manufacture of polyimide resin (X) of the present invention, in addition to the aforementioned tetracarboxylic acid component and diamine component, a capping agent may also be used. As a capping agent, monoamines or dicarboxylic acids are preferred. The amount of capping agent introduced is preferably 0.0001 to 0.1 mol relative to 1 mol of tetracarboxylic acid component, and particularly preferably 0.001 to 0.06 mol. Examples of monoamine capping agents include, for example, methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, and 4-methylaniline. Among these, benzylamine and aniline are suitable. As a dicarboxylic acid capping agent, dicarboxylic acids are preferred, and a portion thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, and 4-cyclohexene-1,2-dicarboxylic acid are recommended. Among these, phthalic acid and phthalic anhydride are suitable.

[0141] There are no particular limitations on the method for reacting the aforementioned tetracarboxylic acid component with the diamine component; any known method may be used.

[0142] Specific reaction methods include: (1) adding tetracarboxylic acid, diamine, and reaction solvent into a reactor, stirring at room temperature to 80°C for 0.5 to 30 hours, and then raising the temperature to carry out an imidization reaction; (2) adding diamine and reaction solvent into a reactor and dissolving them, then adding tetracarboxylic acid, stirring at room temperature to 80°C for 0.5 to 30 hours as needed, and then raising the temperature to carry out an imidization reaction; (3) adding tetracarboxylic acid, diamine, and reaction solvent into a reactor, and immediately raising the temperature to carry out an imidization reaction, etc.

[0143] The reaction solvent used in the manufacture of polyimide resin (X) can be any solvent that does not hinder the imidization reaction and can dissolve the resulting polyimide. Examples of such solvents include aprotic solvents, phenolic solvents, ether solvents, and carbonate solvents.

[0144] Specific examples of aprotic solvents include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolinone, and tetramethylurea; lactone solvents such as γ-butyrolactone and γ-valerolactone; phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphonitramide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; ketone solvents such as acetone, cyclohexanone, and methylcyclohexanone; amine solvents such as picolinone and pyridine; and ester solvents such as (2-methoxy-1-methylethyl) acetate.

[0145] Specific examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol.

[0146] Specific examples of ether-based solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, and 1,4-dioxane.

[0147] In addition, specific examples of carbonate-based solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate.

[0148] Among the above-mentioned reaction solvents, amide-based solvents or lactone-based solvents are preferred. Furthermore, the above-mentioned reaction solvents can be used alone or in combination of two or more.

[0149] In the imidization reaction, a Dean-Stark apparatus or similar device is preferred, and the reaction is carried out while removing the generated water during manufacturing. By performing this operation, the degree of polymerization and the imidization rate can be further increased.

[0150] In the above imidization reaction, known imidization catalysts can be used. Examples of imidization catalysts include base catalysts and acid catalysts.

[0151] Examples of base catalysts include organic base catalysts such as pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-dimethylpyridine, 2,6-dimethylpyridine, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, and N,N-diethylaniline, as well as inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate.

[0152] In addition, examples of acid catalysts include crotonic acid, acrylic acid, trans-3-hexanoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid. The above-mentioned imidization catalysts can be used alone or in combination of two or more.

[0153] From an operational point of view, the use of a base catalyst is preferred, the use of an organic base catalyst is more preferred, the use of triethylamine is even more preferred, and the use of a combination of triethylamine and triethylenediamine is particularly preferred.

[0154] From the viewpoint of inhibiting reaction rate and gelation, the temperature for the imidization reaction is preferably 120–250°C, more preferably 160–200°C. Furthermore, the reaction time, starting after the distillation of water begins, is preferably 0.5–10 hours.

[0155] <Fluoropolymer (Y)>

[0156] The fluoropolymer (Y) in this invention is preferably a polymer having structural units derived from fluorinated monomers, and more preferably a polymer having structural units derived from monomers containing fluorinated alkyl groups.

[0157] The fluorinated polymer (Y) in this invention is preferably a fluorinated acrylic polymer.

[0158] The aforementioned fluorinated acrylic polymer preferably contains structural units derived from fluorinated acrylic monomers, more preferably contains structural units derived from fluorinated acrylic monomers and structural units derived from acrylic monomers having hydrophilic groups.

[0159] As a fluorinated acrylic monomer, a monomer having a perfluoroalkyl group is preferred.

[0160] Examples of acrylic monomers with hydrophilic groups include acrylic acid, methacrylic acid, hydroxyalkyl (meth)acrylate, polyalkylene glycol (meth)acrylate, acrylamide, and methacrylamide.

[0161] Fluorinated acrylic polymers may also contain acrylic monomers with hydrophobic groups. Examples of acrylic monomers with hydrophobic groups include alkyl (meth)acrylates, (meth)acrylates containing organosilicon, and aryl (meth)acrylates.

[0162] The term "(meth)acrylate" here means "acrylate or methacrylate".

[0163] Fluorinated acrylic monomers can also be copolymerized with other monomers containing vinyl groups.

[0164] By using a fluorinated polymer in the polyimide resin composition of the present invention, even when using a polyimide whose polyimide backbone includes a flexible organosilicon portion that is easily hydrolyzed under high temperature and humidity conditions, the molecular weight hardly decreases, and the peelability from supports such as tapes is also good. In addition, the resulting film also has excellent transparency.

[0165] Commercially available products containing fluoropolymers (Y) include LE-605, LE-607, LE-605DM, and LE-607DM manufactured by Kyoei Chemical Co., Ltd.

[0166] In the polyimide resin composition of the present invention, the content of fluoropolymer (Y) relative to 100 parts by weight of polyimide resin (X) is preferably 0.01 to 1 part by weight, more preferably 0.05 to 0.9 parts by weight, further preferably 0.1 to 0.8 parts by weight, and even more preferably 0.2 to 0.7 parts by weight.

[0167] Properties of Polyimide Resin Compositions

[0168] By using the polyimide resin composition of the present invention, a film with excellent peelability from a support such as a tape can be formed, which also suppresses molecular weight reduction under high temperature and humidity conditions and exhibits excellent colorless transparency. The suitable physical properties of the film obtained by using the polyimide resin composition of the present invention are as follows.

[0169] Regarding the total light transmittance, when forming a film with a thickness of 30 μm, it is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more.

[0170] Regarding haze, when forming a film with a thickness of 30 μm, it is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less.

[0171] For the yellow index (YI), when forming a film with a thickness of 30 μm, it is preferably 6.0 or less, more preferably 3.0 or less, and even more preferably 1.5 or less.

[0172] Total transmittance, haze, and yellowness index (YI) can be specifically determined by the methods described in the examples.

[0173] For the absolute value of the thickness phase difference (Rth), when forming a thin film with a thickness of 30 μm, it is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less.

[0174] The glass transition temperature (Tg) is preferably 150–300°C, more preferably 150–280°C, and even more preferably 150–250°C.

[0175] In addition, the tensile modulus is preferably 2.1 GPa or less, more preferably 2.0 GPa or less, and even more preferably 1.8 GPa or less.

[0176] By setting the tensile modulus to this range, highly flexible polyimide films suitable for flexible displays and the like can be produced.

[0177] The tensile strength is preferably 40 MPa or more, more preferably 50 MPa or more, and even more preferably 60 MPa or more.

[0178] The tensile modulus and tensile strength are values ​​determined according to JIS K7127, and can be measured using, for example, a tensile testing machine such as the "StrograpHVG-1E" manufactured by Toyo Seiki Co., Ltd.

[0179] [Polyimide varnish]

[0180] The polyimide varnish of the present invention is formed by dissolving the polyimide resin composition of the present invention in an organic solvent. That is, the polyimide varnish of the present invention comprises the polyimide resin composition of the present invention and an organic solvent, and the polyimide resin composition is dissolved in the organic solvent.

[0181] The organic solvent can dissolve the polyimide resin (X) and the fluoropolymer (Y) without particular limitation. As the reaction solvent used in the manufacture of polyimide resin, it is preferable to use two or more of the above-mentioned compounds alone or in combination.

[0182] The polyimide varnish of the present invention can be a polyimide solution itself formed by dissolving polyimide resin (X) obtained by polymerization in a reaction solvent, or it can be a solution formed by further adding a diluting solvent to the polyimide solution.

[0183] The polyimide resin composition of the present invention is solvent-soluble, and therefore can be formulated into a high-concentration varnish that is stable at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40% by mass, more preferably 10 to 30% by mass of polyimide resin (X). Furthermore, relative to 100 parts by mass of polyimide resin (X), it preferably contains 0.003 to 0.3 parts by mass of fluoropolymer (Y), more preferably 0.015 to 0.3 parts by mass, further preferably 0.03 to 0.25 parts by mass, and even more preferably 0.08 to 0.2 parts by mass.

[0184] The viscosity of the polyimide varnish is preferably 1–200 Pa·s, more preferably 5–150 Pa·s. The viscosity of the polyimide varnish is the value measured using an E-type viscometer at 25°C.

[0185] In addition, without compromising the required properties of the polyimide film, the polyimide varnish of the present invention may also contain various additives such as inorganic fillers, adhesion promoters, flame retardants, ultraviolet absorbers, surfactants, leveling agents, defoamers, fluorescent whitening agents, crosslinking agents, polymerization initiators, and photosensitizers.

[0186] The manufacturing method of the polyimide varnish of the present invention is not particularly limited, and known methods can be used.

[0187] The ultraviolet absorber exemplified as the aforementioned additive can be any suitable ultraviolet absorber. Specific examples include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzoic acid ester-based ultraviolet absorbers, triazine-based ultraviolet absorbers, hindered amine-based ultraviolet absorbers, and inorganic particulate ultraviolet absorbers. Furthermore, organic ultraviolet absorbers such as oxalate aniline-based ultraviolet absorbers and malonic acid ester-based ultraviolet absorbers can also be used. Only one ultraviolet absorber may be used, or two or more may be used in combination. Benzotriazole-based and triazine-based ultraviolet absorbers are preferred, and benzotriazole-based ultraviolet absorbers are more preferred.

[0188] The amount of ultraviolet absorber added to the resin composition relative to 100 parts by weight of polyimide resin (X) is preferably 0.01 to 6 parts by weight, more preferably 0.1 to 5 parts by weight, and even more preferably 0.5 to 4 parts by weight. When the amount of ultraviolet absorber is too high, the optical properties, heat resistance, and other properties of the polyimide resin may decrease, and haze may occur in the film.

[0189] In this invention, the ultraviolet absorber can achieve the effect of an ultraviolet absorber in the resin composition. Therefore, the compound added as an ultraviolet absorber can exist in the resin composition with its original structure, or the compound can be modified by heat treatment to retain the ultraviolet absorption effect. In addition, the ultraviolet absorber is preferably uniformly mixed with the polyimide resin (X) in the resin composition.

[0190] [Polyimide film]

[0191] The polyimide film of the present invention comprises the polyimide resin composition of the present invention. Therefore, the polyimide film of the present invention exhibits excellent colorless transparency, and its molecular weight does not decrease even when placed in a high-temperature and high-humidity environment, thus demonstrating excellent storage stability.

[0192] The suitable physical properties of the polyimide film of the present invention are shown in <Characteristics of Polyimide Resin Compositions>.

[0193] The method for manufacturing the polyimide film of the present invention is not particularly limited, and known methods can be used. Examples include: coating the polyimide varnish of the present invention onto a smooth support such as a glass plate, metal plate, or plastic, or forming it into a film, removing organic solvents such as reaction solvents and diluents contained in the varnish by heating, and then peeling it off from the support. Industrially, a method is preferred where the polyimide varnish is coated onto a metallic strip, and then the organic solvents contained in the varnish are removed by heating and peeled off from the strip.

[0194] For organic solvents, it is preferable to evaporate the organic solvent at a temperature below 120°C to form a self-supporting film, and then peel it off from the support.

[0195] The polyimide resin composition of the present invention has excellent peelability from the support, so that even if the resulting self-supporting film is soft, it can be peeled off without damaging the film.

[0196] Next, the end of the self-supporting film peeled from the support is preferably fixed and dried at a temperature above the boiling point of the organic solvent used to manufacture a polyimide film. It is also preferred to dry under a nitrogen atmosphere. The pressure of the drying atmosphere can be reduced pressure, normal pressure, or pressurized pressure. The heating temperature for drying the self-supporting film to manufacture the polyimide film is not particularly limited, but is preferably 200–400°C.

[0197] The thickness of the polyimide film of the present invention can be appropriately selected according to the application, etc., preferably in the range of 1 to 250 μm, more preferably 5 to 100 μm, and even more preferably 10 to 80 μm. By making the thickness 1 to 250 μm, it can be practically used as a self-supporting film.

[0198] The thickness of the polyimide film can be easily controlled by adjusting the concentration and viscosity of the solid components in the polyimide varnish.

[0199] The polyimide film of the present invention is suitable for use as a film in various components such as color filters, flexible displays, semiconductor components, and optical components. The polyimide film of the present invention is particularly suitable for use as a substrate in image display devices such as liquid crystal displays and OLED displays.

[0200] Example

[0201] The present invention will now be specifically described using examples. However, the present invention is not limited to these examples.

[0202] The solid content concentration of the polyimide varnishes obtained in the examples and comparative examples and the various physical properties of the polyimide films were determined by the methods shown below, and the various evaluations of the polyimide films were performed.

[0203] (1) Solid component concentration

[0204] The sample was heated at 320°C for 120 minutes using a small electric furnace “MMF-1” manufactured by AS ONE CORPORATION, and the concentration of solid components was calculated based on the mass difference of the sample before and after heating.

[0205] (2) Film thickness

[0206] The film thickness was measured using a micrometer manufactured by Mitutoyo Co., Ltd.

[0207] (3) Peelability

[0208] As described in the embodiments and comparative examples, polyimide varnish was applied to an SUS substrate processed with #1000 varnish, and the substrate was kept at 100°C for 20 minutes to allow the solvent to evaporate, thereby obtaining a one-time dried film. The ability to peel the one-time dried film from the SUS substrate was evaluated. In Table 1, "able to peel" is marked as 0, and "unable to peel" is marked as ×. Here, "unable to peel" means that the adhesion between the SUS substrate and the film is strong, and a portion of the one-time dried film is damaged during peeling.

[0209] (4) Logarithmic viscosity of polyimide film

[0210] For the logarithmic viscosity of the polyimide film, the polyimide film was uniformly dissolved in N-methyl-2-pyrrolidone to prepare a solution with a concentration of 0.5 g / dL. The solution viscosity of the solution and solvent was measured at 30°C using a Cannon-Fensk viscometer and calculated using the following formula.

[0211] Logarithmic viscosity = {ln(viscosity of polyimide film preparation solution / solvent viscosity)} / solution concentration

[0212] (5) Damp and hot environment test (evaluation of molecular weight change)

[0213] The polyimide film was treated for 120 hours in a constant temperature and humidity chamber at 60°C and 90% RH. Afterwards, the logarithmic viscosity after the damp heat environment test was measured using the same method as for the logarithmic viscosity of the polyimide film in (4). The difference in logarithmic viscosity before and after the damp heat environment test was calculated to evaluate the change in molecular weight. The smaller the difference in logarithmic viscosity before and after the damp heat environment test, the more effectively the decrease in molecular weight can be suppressed.

[0214] (6) Total transmittance, yellow index (YI) and haze

[0215] Total transmittance, YI, and haze were measured using a color / turbidity simultaneous measuring instrument "COH400" manufactured by Nippon Denshoku Kogyo Co., Ltd.

[0216] Total transmittance and YI were measured according to JIS K7361-1:1997, and haze was measured according to JIS K7136:2000.

[0217] In the examples and comparative examples, the tetracarboxylic acid component and the diamine component used as raw materials for polyimide resin, and their abbreviations are as follows.

[0218] <Tetracarboxylic acid component>

[0219] HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd.; compound represented by formula (a-1))

[0220] <Diamine component>

[0221] X-22-9409: Two-terminal amino-modified silicone oil "X-22-9409" (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; compound shown in formula (b-1))

[0222] HFBAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (prepared by Seika Co., Ltd.; compound shown in formula (b-2-1)

[0223] <Example 1>

[0224] In a 0.3L five-necked round-bottom glass flask equipped with a Dean-Stark apparatus (with stainless steel crescent-shaped stirring blades, a nitrogen inlet pipe, a condenser), a thermometer, and glass end caps, 29.034g (0.056 mol) of HFBAPP, 18.76g (0.014 mol) of X-22-9409, 50g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation), and 0.039g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and 3.54g of triethylamine (manufactured by Kanto Chemical Co., Ltd.) as catalysts were added. The mixture was stirred at 200 rpm under a nitrogen atmosphere to obtain a solution. HPMDA 15.692 g (0.070 mol) and γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) 13.5 g were added to the solution, and the reaction system was heated to 200°C over approximately 20 minutes using a covered heater. The distilled-off components were collected, and the reaction system was maintained at 200°C for 3 hours. Then, N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Corporation) 78.76 g was added, and the mixture was stirred at approximately 100°C for about 1 hour to obtain a homogeneous polyimide solution with a solid content of 30% by mass.

[0225] To obtain a polyimide varnish, 0.5 parts by weight (converted from active ingredient) of a fluoropolymer (LE-607DM, manufactured by Kyoei Chemical Co., Ltd., 30% dimethylacetamide solution) were added to the obtained polyimide solution relative to 100 parts by weight of the polyimide resin.

[0226] The obtained polyimide varnish was then coated onto an SUS substrate processed with #1000 varnish and kept at 100°C for 20 minutes to allow the solvent to evaporate, thereby obtaining a self-supporting, colorless, transparent, one-time dried film. The aforementioned peelability evaluation was performed when the polyimide film was peeled off the SUS substrate. The film was then fixed to a stainless steel frame and dried at 230°C under a nitrogen atmosphere for 2 hours to remove the solvent, resulting in a film with a thickness of 66 μm. FT-IR analysis of the obtained film confirmed the disappearance of the raw material peaks and the appearance of peaks originating from the imide backbone. The peelability evaluation results and the evaluation results of the polyimide film are shown in Table 1.

[0227] <Example 2>

[0228] A polyimide film with a thickness of 54 μm was obtained by adding 0.1 parts by weight (converted to active ingredient) of LE-607DM (fluoropolymer, manufactured by Kyoei Chemical Co., Ltd.) from Example 1 to 100 parts by weight of polyimide resin, except that the addition was made using the same method as in Example 1. The evaluation results are shown in Table 1.

[0229] <Comparative Example 1>

[0230] Replacing 100 parts by weight of polyimide resin, LE-607DM (fluoropolymer, manufactured by Kyoeisha Chemical Co., Ltd.) in Example 1 was replaced with 0.2 parts by weight of phosphate ester-based release agent JP-502 (manufactured by Jōhoku Chemical Industry Co., Ltd., diethyl phosphonate: monoethyl phosphonate = 1:1 (molar ratio)). Otherwise, a polyimide film with a thickness of 47 μm was obtained using the same method as in Example 1. The evaluation results are shown in Table 1.

[0231] <Comparative Example 2>

[0232] In Example 1, LE-607DM (a fluoropolymer, manufactured by Kyoei Chemicals Co., Ltd.) was not added. Otherwise, a polyimide film with a thickness of 60 μm was obtained using the same method as in Example 1. The evaluation results are shown in Table 1.

[0233] [Table 1]

[0234] Table 1

[0235]

[0236] *1: Amount relative to 100 parts by weight of polyimide resin

[0237] As shown in Table 1, it can be seen that the polyimide films formed from the polyimide resin composition of the present invention exhibit excellent peelability, suppressed molecular weight reduction under high temperature and high humidity conditions, and excellent colorless transparency.

Claims

1. A polyimide resin composition comprising: a polyimide resin (X) containing repeating units of formula (1) and formula (2), and a fluoropolymer (Y), In equation (1), R 1 ~R 4 Each is independently a monovalent aliphatic group or a monovalent aromatic group, Z 1 and Z 2 Each is independently a divalent aliphatic group or a divalent aromatic group, where r is a positive integer, and R 5 It is a tetravalent alicyclic group with 4 to 39 carbon atoms. In equation (2), R 6 Φ is a tetravalent alicyclic group having 4 to 39 carbon atoms, and Φ is a divalent aliphatic group, alicyclic group, aromatic group, or a combination thereof having a total of 2 to 39 carbon atoms. As a bonding group, Φ may optionally have at least one selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-. The ratio of repeating units as shown in formula (1) in the polyimide resin (X) is 10 to 50 mol%. The repeating unit shown in formula (1) is composed of structural units (A-1) derived from the compound shown in formula (a-1) below and structural units (B-1) derived from the compound shown in formula (b-1) below. In equation (b-1), R 1 ~R 4 Each is independently a monovalent aliphatic group or a monovalent aromatic group, Z 1 and Z 2 Each can be independently a divalent aliphatic group or a divalent aromatic group, where r is a positive integer. The repeating unit shown in formula (2) is composed of structural units (A-1) and (B-2) derived from the compound shown in formula (a-1) below, wherein structural unit (B-2) is structural unit (B-2-1) derived from the compound shown in formula (b-2-1) below. The proportion of structural units (A-1) derived from tetracarboxylic dianhydride in the polyimide resin (X) is 50 mol% or more. The proportion of structural units (B-1) derived from diamines in the polyimide resin (X) is 10–50 mol%. The proportion of structural units (B-2) derived from diamines in the polyimide resin (X) is 50–90 mol%. The content of fluoropolymer (Y) is 0.01 to 1 part by weight relative to 100 parts by weight of polyimide resin (X). Fluoropolymer (Y) is a fluorinated acrylic polymer.

2. A polyimide varnish, which is formed by dissolving the polyimide resin composition of claim 1 in an organic solvent.

3. A polyimide film comprising the polyimide resin composition of claim 1.

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