Polyamide acid, polyamide acid composition, polyimide, polyimide film, laminate, method for producing laminate, and electronic device

Abstract

A polyamide acid according to the present invention includes a tetracarboxylic acid dianhydride residue and a diamine residue. The tetracarboxylic acid dianhydride residue includes a 3,3',4,4'- biphenyltetracarboxylic acid dianhydride residue. The diamine residue includes a p-phenylenediamine residue and a siloxane diamine residue. At least one of the tetracarboxylic acid dianhydride residue and the diamine residue further includes a residue derived from a compound in which a plurality of aromatic rings are linked via a linking group. The linking group is one or more items selected from the group consisting of ether groups and ester groups.

Description

Polyamic acid, polyamic acid composition, polyimide, polyimide film, laminate, method for producing laminate, and electronic device

[0001] The present invention relates to a polyamic acid, a polyamic acid composition, a polyimide, a polyimide film, a laminate, a method for producing a laminate, and an electronic device.

[0002] With the rapid progress of displays such as liquid crystal displays, organic ELs, and electronic papers, and electronic devices such as solar cells and touch panels, devices are becoming thinner, lighter, and more flexible. In these devices, polyimide is used as a substrate material instead of a glass substrate.

[0003] In these devices, various electronic elements, such as thin film transistors (TFTs) and transparent electrodes, are formed on the substrate, and a high-temperature process is required for the formation of these electronic elements. Since polyimide has sufficient heat resistance to withstand high-temperature processes, it is suitable as a substrate material for flexible displays and the like.

[0004] Polyimide obtained from a polyamic acid composition containing a polyamic acid and an organic solvent is used not only for applications replacing the glass substrate of electronic devices, insulating films used in semiconductor devices, protective coating agents, etc., but also as a planarization film for TFT substrates for display devices (see, for example, Patent Document 1). The above planarization film is provided, for example, on a support on which an inorganic oxide film such as a silicon oxide film is formed.

[0005] Japanese Patent Application Laid-Open No. 2021-34578

[0006] In recent years, in organic EL display devices and semiconductor devices, the process temperature may become high due to reasons such as an increase in the size of the substrate and an improvement in productivity. In such a high-temperature process, the adhesion between the polyimide film and the inorganic oxide film may decrease. Further, internal stress (hereinafter, may be simply referred to as "internal stress") generated at the interface between the support and the polyimide film tends to increase due to heating and cooling when forming a polyimide film on the support to obtain a laminate. When the internal stress increases, the obtained laminate is likely to warp, which may make it difficult to apply to electronic devices.

[0007] Using only the technology described in Patent Document 1, it is difficult to obtain a polyimide that exhibits excellent adhesion to inorganic oxide films in high-temperature processes (hereinafter sometimes referred to as "heat-resistant adhesion") and can reduce internal stress.

[0008] In view of the above, the present invention aims to provide a polyamic acid and a polyamic acid composition that can produce a polyimide with excellent heat resistance and adhesion while reducing internal stress. The present invention also aims to provide a polyimide, a polyimide film, a laminate, and an electronic device produced using the polyamic acid composition. Furthermore, the present invention also aims to provide a method for producing a laminate using the polyamic acid composition.

[0009] <Aspects of the Invention> The present invention includes the following aspects.

[0010] [1] A polyamic acid having a tetracarboxylic dianhydride residue and a diamine residue, wherein the tetracarboxylic dianhydride residue comprises a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue, the diamine residue comprises a p-phenylenediamine residue and a siloxanediamine residue, at least one of the tetracarboxylic dianhydride residue and the diamine residue further comprises a residue derived from a compound in which a plurality of aromatic rings are linked via a linking group, the linking group is one or more selected from the group consisting of an ether group and an ester group, the content of the siloxanediamine residue is 0.01 mol% or more and 0.40 mol% or less with respect to 100 mol% of the total amount of the tetracarboxylic dianhydride residue and the total amount of the diamine residue, and the content of the residue derived from a compound in which a plurality of aromatic rings are linked via a linking group is 0.5 mol% or more and 5.0 mol% or less with respect to 100 mol% of the total amount of the tetracarboxylic dianhydride residue and the total amount of the diamine residue.

[0011] [2] The polyamic acid according to [1], wherein the residue derived from the compound in which the plurality of aromatic rings are linked via a linking group is one or more selected from the group consisting of a tetravalent organic group represented by the following chemical formula (1), a tetravalent organic group represented by the following chemical formula (2), a divalent organic group represented by the following chemical formula (3), a divalent organic group represented by the following chemical formula (4), a divalent organic group represented by the following chemical formula (5), a tetravalent organic group represented by the following chemical formula (6), and a divalent organic group represented by the following chemical formula (7).

[0012]

[0013] [3] The polyamic acid according to [1] or [2], wherein the siloxanediamine residue is a divalent organic group represented by the following general formula (8).

[0014]

[0015] In the above general formula (8), R １ and R ２ Each of these independently represents a divalent hydrocarbon group, and n represents an integer between 1 and 5.

[0016] [4] A polyamic acid composition comprising the polyamic acid described in any one of [1] to [3] above and an organic solvent.

[0017] [5] The polyamic acid composition according to [4], further comprising one or more compounds selected from the group consisting of imidazole compounds and phosphorus-containing compounds.

[0018] [6] The polyamic acid composition according to [5], wherein the amount of one or more compounds selected from the group consisting of the imidazole compound and the phosphorus-containing compound is 0.1 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the polyamic acid.

[0019] [7] A polyimide which is an imide of a polyamic acid according to any one of [1] to [3] above.

[0020] [8] A polyimide film containing the polyimide described in [7] above.

[0021] [9] A laminate having a support and the polyimide film described in [8] above.

[0022]

[10] The laminate according to [9], further comprising an inorganic oxide film interposed between the support and the polyimide film, wherein the polyimide film and the inorganic oxide film are in contact.

[0023]

[11] A method for manufacturing a laminate having a support and a polyimide film, comprising: applying a polyamic acid composition according to any one of [4] to [6] onto a support to form a coating film containing the polyamic acid; and heating the coating film to imide the polyamic acid.

[0024]

[12] An electronic device having the polyimide film described in [8] above and an electronic element disposed on the polyimide film.

[0025] According to the present invention, it is possible to provide a polyamic acid and a polyamic acid composition that can produce a polyimide with excellent heat resistance and adhesion while reducing internal stress. Furthermore, according to the present invention, it is also possible to provide a polyimide, a polyimide film, a laminate, and an electronic device produced using the polyamic acid composition. Moreover, according to the present invention, it is also possible to provide a method for producing a laminate using the polyamic acid composition.

[0026] Preferred embodiments of the present invention will be described in detail below, but the present invention is not limited thereto. Furthermore, all academic and patent documents cited herein are incorporated herein by reference.

[0027] First, let's explain the terms used in this specification. A "structural unit" refers to a repeating unit that makes up a polymer. A "polyamic acid" is a polymer that contains a structural unit represented by the following general formula (9) (hereinafter sometimes referred to as "structural unit (9)").

[0028]

[0029] In general formula (9), A １ This represents a tetracarboxylic dianhydride residue (a tetravalent organic group derived from tetracarboxylic dianhydride), A ２ This represents a diamine residue (a divalent organic group derived from a diamine).

[0030] The content of structural unit (9) relative to the total structural units constituting the polyamic acid is, for example, 50 mol% or more and 100 mol% or less, preferably 60 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less, even more preferably 80 mol% or more and 100 mol% or less, even more preferably 90 mol% or more and 100 mol% or less, and may also be 100 mol%.

[0031] In the following, the term "system" may be added after a compound name to comprehensively refer to the compound and its derivatives. Furthermore, when "system" is added after a compound name to represent a polymer name, unless otherwise specified, it means that the repeating units of the polymer originate from the compound or its derivatives. Also, tetracarboxylic dianhydrides may be written as "acid dianhydrides."

[0032] Unless otherwise specified, the components and functional groups exemplified herein may be used individually or in combination of two or more.

[0033] <Preferred Embodiments of the Invention> The polyamic acid according to this embodiment (hereinafter sometimes referred to as "specific polyamic acid") has a tetracarboxylic dianhydride residue and a diamine residue. The tetracarboxylic dianhydride residue includes a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue. The diamine residue includes a p-phenylenediamine residue and a siloxanediamine residue. In other words, the specific polyamic acid includes a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue as the tetracarboxylic dianhydride residue, and includes a p-phenylenediamine residue and a siloxanediamine residue as the diamine residue. Furthermore, at least one of the tetracarboxylic dianhydride residue and the diamine residue further includes a residue derived from a compound in which a plurality of aromatic rings are linked via a linking group. The above linking group is one or more selected from the group consisting of an ether group (-O-) and an ester group (-CO-O-). In the specified polyamic acid, the content of siloxanediamine residues is 0.01 mol% to 0.40 mol% relative to the total amount of tetracarboxylic dianhydride residues and diamine residues (100 mol%). Furthermore, in the specified polyamic acid, the content of residues derived from compounds in which multiple aromatic rings are linked via linking groups is 0.5 mol% to 5.0 mol% relative to the total amount of tetracarboxylic dianhydride residues and diamine residues (100 mol%).

[0034] Hereinafter, 3,3',4,4'-biphenyltetracarboxylic dianhydride may be referred to as "BPDA". Also, p-phenylenediamine may be referred to as "PDA". Furthermore, residues derived from compounds in which multiple aromatic rings are linked via one or more linking groups selected from the group consisting of ether groups and ester groups may be referred to as "specific aromatic compound residues". Furthermore, the content of siloxanediamine residues relative to the total amount of tetracarboxylic dianhydride residues and diamine residues (100 mol%) may be referred to as "SDA residue content". Furthermore, the content of specific aromatic compound residues relative to the total amount of tetracarboxylic dianhydride residues and diamine residues (100 mol%) may be referred to as "SAC residue content".

[0035] Polyimides manufactured using specific polyamic acids exhibit excellent heat resistance and adhesion while reducing internal stress. The reason for this is presumed to be as follows:

[0036] The specific polyamic acid contains BPDA residues and PDA residues. Both BPDA and PDA residues have a rigid structure. Therefore, polyimides produced using the specific polyamic acid tend to have a smaller coefficient of thermal expansion, thus reducing internal stress. Furthermore, the specific polyamic acid contains siloxanediamine residues and has an SDA residue content of 0.01 mol% to 0.40 mol%, so polyimide films produced using this specific polyamic acid have excellent adhesion to inorganic oxide films. On the other hand, because polyimides containing BPDA and PDA residues have a rigid structure, when a laminate of a film containing this polyimide (polyimide film) and an inorganic oxide film is exposed to high temperatures, strain is usually likely to occur near the interface between the polyimide film and the inorganic oxide film. In contrast, the specific polyamic acid contains specific aromatic compound residues with a relatively flexible structure and has an SAC residue content of 0.5 mol% or more, so polyimide films produced using this specific polyamic acid can reduce strain between the film and the inorganic oxide film even at high temperatures. Therefore, polyimide films produced using specific polyamic acids can maintain their adhesion to inorganic oxide films, enhanced by siloxanediamine residues, even at high temperatures. Furthermore, because specific polyamic acids have an SAC residue content of 5.0 mol% or less, they can suppress the increase in internal stress. For these reasons, polyimides produced using specific polyamic acids exhibit excellent heat-resistant adhesion while reducing internal stress.

[0037] In this embodiment, in order to obtain a polyimide with superior heat resistance and adhesion, the SDA residue content is preferably 0.02 mol% or more and 0.40 mol% or less, more preferably 0.04 mol% or more and 0.30 mol% or less, and even more preferably 0.04 mol% or more and 0.25 mol% or less.

[0038] In this embodiment, in order to obtain a polyimide having excellent heat-resistant adhesion, the SAC residue content is preferably 0.6 mol% or more, more preferably 0.8 mol% or more, still more preferably 1.0 mol% or more, and even more preferably 1.1 mol% or more. Further, in this embodiment, in order to obtain a polyimide capable of further reducing internal stress, the SAC residue content is preferably 4.0 mol% or less, more preferably 3.0 mol% or less, and still more preferably 2.0 mol% or less.

[0039] In this embodiment, in order to obtain a polyimide having excellent heat-resistant adhesion, the number of aromatic rings of the specific aromatic compound residue is preferably 2 or 3. Further, in this embodiment, in order to obtain a polyimide having excellent heat-resistant adhesion, the aromatic ring of the specific aromatic compound residue is preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring.

[0040] In this embodiment, only one of the tetracarboxylic dianhydride residue and the diamine residue may have a specific aromatic compound residue, or both the tetracarboxylic dianhydride residue and the diamine residue may have a specific aromatic compound residue.

[0041] The specific polyamic acid may have only a residue derived from a compound in which a plurality of aromatic rings are linked via an ether group (hereinafter sometimes referred to as an "aromatic ether residue") as the specific aromatic compound residue, or may have only a residue derived from a compound in which a plurality of aromatic rings are linked via an ester group (hereinafter sometimes referred to as an "aromatic ester residue") as the specific aromatic compound residue. Further, the specific polyamic acid may have both an aromatic ether residue and an aromatic ester residue as the specific aromatic compound residue. That is, the specific polyamic acid may have at least one selected from the group consisting of an aromatic ether residue and an aromatic ester residue as the specific aromatic compound residue.

[0042] When the tetracarboxylic dianhydride residue has an aromatic ether residue, examples of the aromatic ether residue include a 4,4'-oxydiphthalic anhydride residue, a 3,4'-oxydiphthalic anhydride residue, a 4,4'-(4,4'-isopropylidenediphenoxy)bispht halic anhydride residue, a hydroquinone diphthalic anhydride residue, and the like. When the tetracarboxylic dianhydride residue has an aromatic ether residue, in order to obtain a polyimide having excellent heat-resistant adhesion, the aromatic ether residue is preferably at least one selected from the group consisting of a 4,4'-oxydiphthalic anhydride residue and a 3,4'-oxydiphthalic anhydride residue, and a 4,4'-oxydiphthalic anhydride residue is more preferable. Hereinafter, 4,4'-oxydiphthalic anhydride may be referred to as "ODPA". Further, 3,4'-oxydiphthalic anhydride may be referred to as "a-ODPA".

[0043] When a diamine residue has an aromatic ether residue, examples of such aromatic ether residues include 4,4'-oxydianiline residues, 3,4'-oxydianiline residues, 2,2-bis[4-(4-aminophenoxy)phenyl]propane residues, 1,4-bis(4-aminophenoxy)benzene residues, 1,3-bis(4-aminophenoxy)benzene residues, 1,3-bis(3-aminophenoxy)benzene residues, 4,4'-bis(4-aminophenoxy)biphenyl residues, bis[4-(4-aminophenoxy)phenyl]sulfone residues, and bis[4-(3-aminophenoxy)phenyl]sulfone residues. When a diamine residue has an aromatic ether residue, in order to obtain a polyimide with superior heat resistance and adhesion, the aromatic ether residue is preferably one or more selected from the group consisting of a 4,4'-oxydianiline residue, a 3,4'-oxydianiline residue, and a 1,3-bis(4-aminophenoxy)benzene residue, more preferably one or more selected from the group consisting of a 4,4'-oxydianiline residue and a 1,3-bis(4-aminophenoxy)benzene residue, and even more preferably a 1,3-bis(4-aminophenoxy)benzene residue. Hereinafter, 4,4'-oxydianiline may be referred to as "4,4'-ODA". Also, 3,4'-oxydianiline may be referred to as "3,4'-ODA". Also, 1,3-bis(4-aminophenoxy)benzene may be referred to as "TPE-R".

[0044] When a tetracarboxylic dianhydride residue has an aromatic ester residue, in order to obtain a polyimide with superior heat resistance and adhesion, the aromatic ester residue is preferably one or more selected from the group consisting of residues derived from p-phenylenebis(trimellitic acid monoester anhydride) and residues derived from (1,3-dioxoisobenzofuran-5-yl)1,3-dioxoisobenzofuran-5-carboxylate (hereinafter sometimes referred to as "8CI"), with the 8CI residue being more preferred.

[0045] When a diamine residue contains an aromatic ester residue, in order to obtain a polyimide with superior heat resistance and adhesion, the aromatic ester residue is preferably derived from 4-aminophenyl-4-aminobenzoate (hereinafter sometimes referred to as "4-BAAB").

[0046] To obtain a polyimide with superior heat-resistant adhesion while reducing internal stress, it is preferable that the aromatic ether residue be one or more selected from the group consisting of ODPA residues, α-ODPA residues, 4,4'-ODA residues, 3,4'-ODA residues, and TPE-R residues. Furthermore, to obtain a polyimide with superior heat-resistant adhesion while reducing internal stress, it is preferable that the aromatic ester residue be one or more selected from the group consisting of 8CI residues and 4-BAAB residues, with 4-BAAB residues being more preferable. In other words, to obtain a polyimide with superior heat-resistant adhesion while reducing internal stress, it is preferable that the specific aromatic compound residue be one or more selected from the group consisting of ODPA residues, α-ODPA residues, 4,4'-ODA residues, 3,4'-ODA residues, TPE-R residues, 8CI residues, and 4-BAAB residues.

[0047] The ODPA residue is a tetravalent organic group represented by the following chemical formula (1). The α-ODPA residue is a tetravalent organic group represented by the following chemical formula (2). The 4,4'-ODA residue is a divalent organic group represented by the following chemical formula (3). The 3,4'-ODA residue is a divalent organic group represented by the following chemical formula (4). The TPE-R residue is a divalent organic group represented by the following chemical formula (5). The 8CI residue is a tetravalent organic group represented by the following chemical formula (6). The 4-BAAB residue is a divalent organic group represented by the following chemical formula (7).

[0048]

[0049] In this embodiment, in order to obtain a polyimide with superior heat resistance and adhesion, it is preferable that the siloxanediamine residue is a divalent organic group represented by the following general formula (8).

[0050]

[0051] In general formula (8), R １ and R ２ Each of these independently represents a divalent hydrocarbon group, and n represents an integer between 1 and 5. In order to obtain a polyimide with even better heat resistance and adhesion, R １ and R ２ In each case, an alkylene group having 1 to 5 carbon atoms is preferred, and an alkylene group having 2 to 4 carbon atoms is more preferred. Furthermore, to obtain a polyimide with even better heat resistance and adhesion, n is preferably 1 to 3, and more preferably 1.

[0052] To obtain a polyimide with particularly excellent heat resistance and adhesion, a siloxanediamine residue of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (hereinafter sometimes referred to as "PAM-E") is preferred.

[0053] Other acid dianhydrides (acid dianhydrides) besides those described above may be used as acid dianhydrides for synthesizing specific polyamic acids. Examples of other acid dianhydrides include pyromellitic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, and derivatives thereof, which may be used individually or in combination of two or more.

[0054] Other diamines (other diamines) may be used as diamines for synthesizing specific polyamic acids, in addition to those mentioned above. Examples of other diamines include 2,2'-bis(trifluoromethyl)benzidine, 1,4-diaminocyclohexane, m-phenylenediamine, 9,9-bis(4-aminophenyl)fluorene, 4,4'-diaminobenzanilide, N,N'-bis(4-aminophenyl)terephthalamide, 4,4'-diaminodiphenylsulfone, m-tolidine, o-tolidine, 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'-dihydroxybiphenyl, 4,4'-methylenebis(cyclohexaneamine), and derivatives thereof, which may be used individually or in combination of two or more.

[0055] To obtain a polyimide that can further reduce internal stress, the content of BPDA residues relative to the total acid dianhydride residues (100 mol%) constituting the specific polyamic acid is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0056] To obtain a polyimide that can further reduce internal stress, the content of PDA residues relative to the total diamine residues (100 mol%) constituting the specific polyamic acid is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0057] To obtain a polyimide that can further reduce internal stress, the total content of BPDA residues and PDA residues is preferably 80 mol% or more, more preferably 90 mol% or more, and may be 91 mol% or more, 92 mol% or more, 93 mol% or more, 94 mol% or more, or 95 mol% or more, based on the total of all acid dianhydride residues and all diamine residues constituting the specific polyamic acid (100 mol%).

[0058] When a specific polyamic acid has aromatic ether residues as acid dianhydride residues, in order to obtain a polyimide with superior heat resistance and adhesion while further reducing internal stress, the content of aromatic ether residues as acid dianhydride residues is preferably 1.0 mol% to 10.0 mol%, and more preferably 1.5 mol% to 5.0 mol%, relative to the total acid dianhydride residues constituting the specific polyamic acid (100 mol%).

[0059] When a specific polyamic acid has an aromatic ether residue as a diamine residue, in order to obtain a polyimide with superior heat resistance and adhesion while further reducing internal stress, the content of the aromatic ether residue as a diamine residue is preferably 1.0 mol% to 10.0 mol%, and more preferably 1.5 mol% to 5.0 mol%, relative to the total diamine residues constituting the specific polyamic acid (100 mol%).

[0060] When a specific polyamic acid has aromatic ester residues as acid dianhydride residues, in order to obtain a polyimide with superior heat resistance and adhesion while further reducing internal stress, the content of aromatic ester residues as acid dianhydride residues is preferably 1.0 mol% to 10.0 mol%, and more preferably 1.5 mol% to 5.0 mol%, relative to the total acid dianhydride residues constituting the specific polyamic acid (100 mol%).

[0061] When a specific polyamic acid has aromatic ester residues as diamine residues, in order to obtain a polyimide with superior heat resistance and adhesion while further reducing internal stress, the content of aromatic ester residues as diamine residues is preferably 1.0 mol% to 10.0 mol%, and more preferably 1.5 mol% to 5.0 mol%, relative to the total diamine residues constituting the specific polyamic acid (100 mol%).

[0062] In order to obtain a polyimide with superior heat resistance and adhesion while further reducing internal stress, the total content of BPDA residues, PDA residues, specific aromatic compound residues, and siloxanediamine residues is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, and may also be 90 mol% or more, 95 mol% or more, 96 mol% or more, 97 mol% or more, 98 mol% or more, or 99 mol% or more, or even 100 mol%.

[0063] When a specific polyamic acid has aromatic ether residues, in order to obtain a polyimide with superior heat resistance and adhesion while further reducing internal stress, the total content of BPDA residues, PDA residues, aromatic ether residues, and siloxanediamine residues is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, and may also be 90 mol% or more, 95 mol% or more, 96 mol% or more, 97 mol% or more, 98 mol% or more, or 99 mol% or more, or even 100 mol%.

[0064] When a specific polyamic acid has aromatic ester residues, in order to obtain a polyimide with superior heat resistance and adhesion while further reducing internal stress, the total content of BPDA residues, PDA residues, aromatic ester residues, and siloxanediamine residues is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, and may also be 90 mol% or more, 95 mol% or more, 96 mol% or more, 97 mol% or more, 98 mol% or more, or 99 mol% or more, or even 100 mol%.

[0065] In order to obtain a polyimide with even better heat resistance and adhesion while further reducing internal stress, the specific polyamic acid preferably satisfies the following conditions 1 or 2, more preferably satisfies condition 3, even more preferably satisfies condition 4, and even more preferably satisfies condition 5. Condition 1: The specific polyamic acid has one or more aromatic ether residues selected from the group consisting of ODPA residues, 4,4'-ODA residues, 3,4'-ODA residues, and TPE-R residues, and the siloxanediamine residue is a PAM-E residue. Condition 2: The specific polyamic acid has a 4-BAAB residue as an aromatic ester residue, and the siloxanediamine residue is a PAM-E residue. Condition 3: The specific polyamic acid satisfies the above conditions 1 or 2, and the content of BPDA residues relative to the total acid dianhydride residues (100 mol%) constituting the specific polyamic acid is 70 mol% or more. Condition 4: The above condition 3 is met, and the content of PDA residues relative to all diamine residues (100 mol%) constituting the specific polyamic acid is 70 mol% or more. Condition 5: The above condition 4 is met, and the total content of BPDA residues, PDA residues, specific aromatic compound residues, and siloxanediamine residues is 70 mol% or more and 100 mol% or less relative to the total (100 mol%) of all acid dianhydride residues and all diamine residues constituting the specific polyamic acid.

[0066] Specific polyamic acids can be synthesized by known general methods, for example, by reacting a diamine with a tetracarboxylic dianhydride in an organic solvent. An example of a specific synthesis method for specific polyamic acids will be described below. First, a diamine solution is prepared by dissolving or dispersing the diamine in an organic solvent in an inert gas atmosphere such as argon or nitrogen. Then, the tetracarboxylic dianhydride is added to the diamine solution either dissolved or dispersed in an organic solvent, or in a solid state.

[0067] When synthesizing a specific polyamic acid using a diamine and a tetracarboxylic dianhydride, the desired specific polyamic acid (a polymer of diamine and tetracarboxylic dianhydride) can be obtained by adjusting the amount of substance of the diamine (or the amount of each diamine if multiple diamines are used) and the amount of substance of the tetracarboxylic dianhydride (or the amount of each tetracarboxylic dianhydride if multiple tetracarboxylic dianhydrides are used). The mole fraction of each residue in the specific polyamic acid is, for example, the same as the mole fraction of each monomer (each monomer corresponding to each residue) used in the synthesis of the specific polyamic acid. Furthermore, by blending two types of polyamic acids, it is also possible to obtain a specific polyamic acid containing multiple types of tetracarboxylic dianhydride residues and multiple types of diamine residues. The temperature conditions for the reaction between the diamine and the tetracarboxylic dianhydride, i.e., the synthesis reaction of the specific polyamic acid, are not particularly limited, but are, for example, in the range of 20°C to 150°C. The reaction time for the synthesis reaction of the specific polyamic acid is, for example, in the range of 10 minutes to 30 hours.

[0068] The organic solvent used in the synthesis of specific polyamic acids is preferably a solvent capable of dissolving the tetracarboxylic dianhydride and diamine used, and more preferably a solvent capable of dissolving the resulting specific polyamic acid. Examples of organic solvents used in the synthesis of specific polyamic acids include urea-based solvents such as tetramethylurea and N,N-dimethylethylurea; sulfoxide-based solvents such as dimethyl sulfoxide; sulfone-based solvents such as diphenyl sulfone and tetramethyl sulfone; N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N,N-diethylacetamide (DEF), N-methyl-2-pyrrolidone (NMP), N-butyl-2-pyrrolidone (NBP), 3-methoxy-N,N-dimethylpropanamide (MPA), and 3-butoxy-N,N-dimethylpropanamide (BPA). Examples of solvents include amide solvents such as N,N-dimethylpropionamide (DMPA) and hexamethyltriamide; ester solvents such as γ-butyrolactone; alkyl halogenated solvents such as chloroform and methylene chloride; aromatic hydrocarbon solvents such as benzene and toluene; phenolic solvents such as phenol and cresol; ketone solvents such as cyclopentanone; and etheric solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, and p-cresol methyl ether. These solvents are usually used individually, but two or more may be used in appropriate combinations as needed.

[0069] To enhance the solubility and reactivity of specific polyamic acids, the organic solvent used in the synthesis reaction of specific polyamic acids is preferably one or more solvents selected from the group consisting of amide solvents, ketone solvents, ester solvents, and ether solvents, with amide solvents being more preferable. Furthermore, the synthesis reaction of specific polyamic acids is preferably carried out under an inert gas atmosphere such as argon or nitrogen.

[0070] The polyamic acid composition according to this embodiment contains a specific polyamic acid and an organic solvent. Examples of organic solvents included in the polyamic acid composition according to this embodiment include those exemplified as organic solvents usable in the synthesis reaction of the specific polyamic acid. Preferably, one or more solvents selected from the group consisting of amide solvents, ketone solvents, ester solvents, and ether solvents are used, with amide solvents being more preferred.

[0071] When a specific polyamic acid is obtained by the method described above, the reaction solution (the solution after the reaction) itself may be used as the polyamic acid composition according to this embodiment. Alternatively, the specific polyamic acid obtained by removing the solvent from the reaction solution may be dissolved in an organic solvent to prepare the polyamic acid composition according to this embodiment. The content of the specific polyamic acid in the polyamic acid composition according to this embodiment is not particularly limited, but for example, it is 1% by weight or more and 80% by weight or less of the total amount of the polyamic acid composition.

[0072] The weight-average molecular weight of a specific polyamic acid is preferably in the range of 10,000 to 1,000,000, more preferably in the range of 20,000 to 500,000, and even more preferably in the range of 30,000 to 200,000, depending on its application. If the weight-average molecular weight is 10,000 or more, it becomes easy to form a coating film or polyimide film using the specific polyamic acid or the polyimide obtained using the specific polyamic acid. On the other hand, if the weight-average molecular weight is 1,000,000 or less, it exhibits sufficient solubility in the solvent, so a coating film or polyimide film with a smooth surface and uniform thickness can be obtained using the polyamic acid composition. The weight-average molecular weight used here refers to the polyethylene oxide equivalent value measured using gel permeation chromatography (GPC).

[0073] Furthermore, methods for controlling the molecular weight of a specific polyamic acid include using an excess of either the acid dianhydride or the diamine, or quenching the reaction by reacting it with monofunctional acid anhydrides or amines such as phthalic anhydride or aniline. To obtain a polyimide with superior adhesion to inorganic oxide films, it is preferable to polymerize with an excess of diamine. When polymerizing with an excess of either the acid dianhydride or the diamine, a polyimide film with sufficient strength can be obtained if the molar ratio of these components is between 0.95 and 1.05. The above molar ratio is the ratio of the total amount of diamine used in the synthesis of the specific polyamic acid to the total amount of acid dianhydride used in the synthesis of the specific polyamic acid (total amount of diamine / total amount of acid dianhydride). In addition, the coloration of the polyimide obtained using the specific polyamic acid can be further reduced by end-capturing with phthalic anhydride, maleic anhydride, aniline, etc.

[0074] The polyamic acid composition according to this embodiment may further contain one or more compounds selected from the group consisting of imidazole compounds and phosphorus-containing compounds (hereinafter sometimes referred to as "specific additives"). In this specification, imidazole compounds refer to compounds having a 1,3-diazole ring (1,3-diazole ring structure). In this specification, the specific additive is a compound different from the polyamic acid and the solvent. When the polyamic acid composition according to this embodiment contains a specific additive, sufficient molecular motion is imparted to the specific polyamic acid during imidation. As a result, the imidation of the specific polyamic acid proceeds rapidly, and the depolymerization of the specific polyamic acid is also suppressed, so a polyimide with superior heat resistance and adhesion can be obtained. To obtain a polyimide with even superior heat resistance and adhesion, imidazole compounds are preferred as the specific additive.

[0075] To obtain a polyimide with superior heat resistance and adhesion, the amount of the specific additive is preferably 0.1 parts by weight or more and 10 parts by weight or less, more preferably 0.1 parts by weight or more and 5 parts by weight or less, and even more preferably 0.1 parts by weight or more and 1 part by weight or less, per 100 parts by weight of the specific polyamic acid.

[0076] The imidazole compounds that can be added to the polyamic acid composition according to this embodiment are not particularly limited, but examples include 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole. Among these, 2-phenylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole are preferred, and 2-phenylimidazole, 1,2-dimethylimidazole, and 1-benzyl-2-methylimidazole are more preferred.

[0077] The phosphorus-containing compounds that can be added to the polyamic acid composition according to this embodiment are not particularly limited, but examples include phosphate compounds, phosphite compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine compounds, phosphine oxide compounds, phosphorane compounds, phosphazene compounds, and the like. The phosphorus-containing compounds may be esters or condensates thereof of the compounds listed above, may contain cyclic structures, or may form salts with amines, etc. Furthermore, some of these phosphorus-containing compounds, such as phosphite compounds and phosphonic acid compounds, are in a tautomeristic relationship, but they may exist in either state.

[0078] Specific examples of phosphate compounds include trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl) phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, diphenyl(2-ethylhexyl) phosphate, di(isopropylphenyl)phenyl phosphate, monoisodecyl phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, melamine phosphate, dimelamine phosphate, bisphenol A bis(diphenyl phosphate), tris(β-chloropropyl) phosphate, and the like.

[0079] Specific examples of phosphite compounds include triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, triethyl phosphite, triisobutyl phosphite, tris(2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, tris(tridecyl) phosphite, diphenyl phosphite, diethyl phosphite, dibutyl phosphite, dimethyl phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono(tridecyl) phosphite, trilauryl trithiophosphite, diethylhydrogen phosphite, and bis(2-ethylhexyl) phosphite. Examples include hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, diphenyl hydrogen phosphite, tetraphenyl dipropylene glycol diphosphite, bis(decyl)pentaerythritol diphosphite, bis(tridecyl)pentaerythritol diphosphite, tristearyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, triisodecyl phosphite, and 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane.

[0080] Examples of the above-mentioned condensates include condensed phosphate esters. Specific examples of condensed phosphate esters include trialkyl polyphosphates, resorcinol polyphenyl phosphates, resorcinol poly(di-2,6-xylyl) phosphates, and hydroquinone poly(2,6-xylyl) phosphates. Examples of commercially available condensed phosphate esters include "CR-733S," "CR-741," and "PX-200" from Daihachi Chemical Industry Co., Ltd., and "FP-600" from ADEKA Corporation.

[0081] Specific examples of phosphazene compounds include phenoxycyclophosphazene (FP-110, manufactured by Fushimi Pharmaceutical Co., Ltd.) and cyclic cyanophenoxyphosphazene (FP-300, manufactured by Fushimi Pharmaceutical Co., Ltd.).

[0082] The polyimide according to this embodiment is an imidized product of the specific polyamic acid described above. The polyimide according to this embodiment can be obtained by known methods, and the method of production is not particularly limited. Below, an example of a method for obtaining the polyimide according to this embodiment by imidizing the specific polyamic acid will be described. Imidization is carried out by dehydration and cyclization of the specific polyamic acid. This dehydration and cyclization can be carried out by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. Furthermore, the imidization from the specific polyamic acid to the polyimide can be any ratio of 1% to 100%. In other words, a specific polyamic acid that is partially imidized may be synthesized. In particular, when imidization is carried out by heating and increasing the temperature, the cyclization reaction from the specific polyamic acid to the polyimide and the hydrolysis of the specific polyamic acid proceed simultaneously, and the molecular weight of the resulting polyimide may be lower than the molecular weight of the specific polyamic acid. Therefore, from the viewpoint of improving mechanical properties, it is preferable to pre-imidize a portion of the specific polyamic acid in the polyamic acid composition before forming the polyimide film described later. In this specification, a polyamic acid that is partially imidized may also be referred to as "polyamic acid".

[0083] Dehydration and ring closure of the specific polyamic acid can be performed by heating the specific polyamic acid. The method of heating the specific polyamic acid is not particularly limited, but for example, the polyamic acid composition according to this embodiment described above can be applied to a support such as a glass substrate, a metal plate, or a PET film (polyethylene terephthalate film), and then the specific polyamic acid can be heat-treated at a temperature of 40°C to 500°C. This method yields a laminate according to this embodiment having a support and a polyimide film (more specifically, a polyimide film containing an imidized product of the specific polyamic acid) disposed on the support. Alternatively, the polyamic acid composition can be directly placed in a container that has been subjected to a release treatment such as a coating with a fluororesin, and the polyamic acid composition can be heated and dried under reduced pressure to perform dehydration and ring closure of the specific polyamic acid. Polyimide can be obtained by dehydration and ring closure of the specific polyamic acid using these methods. The heating time for each of the above processes varies depending on the amount of polyamic acid composition to be dehydrated and cyclized, and the heating temperature, but generally, it is preferable to set the heating time to a range of 1 minute to 300 minutes after the processing temperature reaches the maximum temperature. In addition, to shorten the heating time and achieve the desired properties, an imidizing agent and / or a dehydration catalyst may be added to the polyamic acid composition, and the polyamic acid composition to which the imidizing agent and / or dehydration catalyst have been added may be heated by the above method to imide it.

[0084] The above-mentioned imidizing agent is not particularly limited, but a tertiary amine can be used. A heterocyclic tertiary amine is preferred as the tertiary amine. Preferred specific examples of heterocyclic tertiary amines include pyridine, picoline, quinoline, isoquinoline, and 1,2-dimethylimidazole. Preferred specific examples of the above-mentioned dehydration catalyst include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride.

[0085] The amount of imidizing agent added is preferably 0.5 to 5.0 molar equivalents relative to the amide group of the specific polyamic acid, more preferably 0.7 to 2.5 molar equivalents, and even more preferably 0.8 to 2.0 molar equivalents. The amount of dehydrating catalyst added is preferably 0.5 to 10.0 molar equivalents relative to the amide group of the specific polyamic acid, more preferably 0.7 to 5.0 molar equivalents, and even more preferably 0.8 to 3.0 molar equivalents. In this specification, "amide group of specific polyamic acid" refers to the amide group produced by the polymerization reaction of a diamine and a tetracarboxylic dianhydride. When adding the imidizing agent and / or dehydrating catalyst to the polyamic acid composition, they may be added directly without dissolving them in an organic solvent, or they may be added after being dissolved in an organic solvent. In methods where the imidizing agent and / or dehydrating catalyst are added directly without dissolving them in an organic solvent, the reaction may proceed rapidly before the imidizing agent and / or dehydrating catalyst can diffuse, potentially leading to gel formation. Therefore, it is preferable to add a solution obtained by dissolving the imidizing agent and / or dehydrating catalyst in an organic solvent to the polyamic acid composition.

[0086] The polyimide film according to this embodiment (more specifically, a polyimide film containing an imidized compound of a specific polyamic acid) has a glass transition temperature (heat resistance) that can withstand the TFT manufacturing process, making it suitable as a substrate material for flexible displays. The polyimide content (more specifically, an imidized compound of a specific polyamic acid) in the polyimide film according to this embodiment is, for example, 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and may be 100% by weight, based on the total amount of the polyimide film. Examples of components other than polyimide in the polyimide film include additives (more specifically, fine particles, etc.) described later.

[0087] The electronic device according to this embodiment (for example, a flexible device) comprises a polyimide film according to this embodiment and electronic elements directly or indirectly disposed on the polyimide film. When manufacturing the electronic device according to this embodiment for use in a flexible display, first, an inorganic substrate such as glass is used as a support, and a polyimide film is formed on it. Then, an electronic device is formed on the support by arranging (forming) electronic elements such as TFTs on the polyimide film. The process of forming TFTs is generally carried out in a wide temperature range of 150°C to 650°C, but in order to actually achieve the desired performance, an oxide semiconductor layer or an a-Si layer is formed at 300°C or higher, and in some cases, the a-Si may be further crystallized with a laser or the like.

[0088] In this case, if the thermal decomposition temperature of the polyimide film is low, outgassing may occur during the formation of electronic elements, causing sublimation to adhere to the inside of the oven and contaminating the furnace, or the inorganic film (such as the barrier film described later) or electronic elements formed on the polyimide film may peel off. Therefore, the 1% weight loss temperature of the polyimide is preferably 450°C or higher, and more preferably 500°C or higher. The upper limit of the 1% weight loss temperature of the polyimide is better the higher it is, for example, 580°C. The 1% weight loss temperature can be adjusted, for example, by changing the content of residues having a rigid structure (more specifically, BPDA residues, PDA residues, etc.). To explain in more detail, before TFT formation, an inorganic film such as a silicon oxide film (SiOx film) or a silicon nitride film (SiNx film) is formed on the polyimide film as a barrier film. In this case, if the polyimide has low heat resistance, if the imidation has not progressed completely, or if there is a large amount of residual solvent, the polyimide and inorganic film may delaminate during the high-temperature process after the inorganic film lamination due to volatile components such as polyimide decomposition gases. For this reason, it is desirable that the 1% weight loss temperature of the polyimide is 450°C or higher, and that the weight loss rate when the polyimide is held isothermally within the range of 400°C to 450°C is 1% or less.

[0089] Furthermore, if the glass transition temperature (Tg) of the polyimide is significantly lower than the process temperature, misalignment may occur during the formation of electronic elements. Therefore, the Tg of the polyimide is preferably 300°C or higher, more preferably 350°C or higher, and even more preferably 400°C or higher. The upper limit of the Tg of the polyimide is better the higher it is, for example, 450°C. In addition, since the coefficient of linear expansion of glass substrates is generally smaller than that of resins, internal stress is generated between the glass substrate and the polyimide film. If the internal stress of the laminate of the glass substrate or electronic elements used as a support and the polyimide film is high, the laminate containing the polyimide film will expand in the high-temperature TFT formation process and then contract when cooled to room temperature, causing problems such as warping or breakage of the glass substrate and delamination of the polyimide film from the glass substrate. Therefore, the internal stress generated in the laminate of the polyimide film and glass substrate is preferably 30 MPa or less, more preferably 20 MPa or less, and even more preferably 10 MPa or less.

[0090] The polyimide according to this embodiment can be suitably used as a material for display substrates such as TFT substrates and touch panel substrates. When using polyimide for the above applications, as described above, an electronic device (more specifically, an electronic device in which electronic elements are formed on a polyimide film) is often formed on a support, and then the polyimide film is peeled off from the support. Alkali-free glass is suitably used as the material for the support.

[0091] Furthermore, after forming an inorganic oxide film on the support, a polyimide film may be formed on the inorganic oxide film. In other words, the laminate according to this embodiment may further include an inorganic oxide film interposed between the support and the polyimide film (more specifically, a polyimide film containing an imidide of a specific polyamic acid). In this case, the polyimide film and the inorganic oxide film may be in contact. As described above, the polyimide film containing an imidide of a specific polyamic acid has excellent heat-resistant adhesion. Therefore, even if the polyimide film and the inorganic oxide film are in contact, interlayer adhesion during high-temperature processes can be improved.

[0092] Examples of the inorganic oxide films mentioned above include silicon oxide films and aluminum oxide films. The thickness of the inorganic oxide film is not particularly limited, but is, for example, 100 nm to 1000 nm. Examples of methods for forming the inorganic oxide film include sputtering and plasma chemical vapor deposition (plasma CVD). When using a silicon oxide film as the inorganic oxide film, a film containing SiOx (where x is a real number between 1.3 and less than 2.0) is preferred. To further improve heat resistance and adhesion, a silicon oxide film containing SiOx (where x is a real number between 1.3 and less than 2.0) at a content of 90% to 100% by weight of the total film amount (hereinafter sometimes simply referred to as "SiOx film") is preferred.

[0093] Next, an example of a method for manufacturing the laminate according to this embodiment will be described in detail. First, the polyamic acid composition according to this embodiment is applied directly to a support or via an inorganic oxide film to form a coated film-containing laminate having a coated film containing a specific polyamic acid and a support. Next, the coated film-containing laminate is heated under conditions such as a temperature of 40°C to 200°C. The heating time in this case is, for example, 3 minutes to 120 minutes. Note that a multi-stage heating process may be provided, such as heating the coated film-containing laminate at 50°C for 30 minutes and then at 100°C for 30 minutes. Next, in order to promote the imidization of the specific polyamic acid in the coated film, the coated film-containing laminate is heated under conditions such as a maximum temperature of 200°C to 500°C. The heating time in this case (heating time at the maximum temperature) is, for example, 1 minute to 300 minutes. In this case, it is preferable to gradually raise the temperature from a low temperature to the maximum temperature. The heating rate is preferably 2°C / min to 10°C / min, and more preferably 4°C / min to 10°C / min. Furthermore, the maximum temperature is preferably in the range of 250°C to 470°C. If the maximum temperature is 250°C or higher, imidation proceeds sufficiently, and if the maximum temperature is 470°C or lower, thermal degradation and discoloration of the polyimide can be suppressed. Alternatively, the temperature may be maintained at any temperature for any length of time before reaching the maximum temperature. The imidation reaction can be carried out in air, under reduced pressure, or in an inert gas such as nitrogen, but to achieve higher transparency, it is preferable to carry it out under reduced pressure or in an inert gas such as nitrogen. As a heating device, known devices such as hot air ovens, infrared ovens, vacuum ovens, inert ovens, and hot plates can be used. Through these steps, the specific polyamic acid in the coated film is imidized, and a laminate having a support and a polyimide film (a film containing the imidized product of the specific polyamic acid) can be obtained (i.e., a laminate according to this embodiment). Alternatively, to shorten the heating time and achieve the desired properties, an imidizing agent or a dehydration catalyst may be added to the polyamic acid composition, and this solution may be heated by the above method to perform imidation.

[0094] A known method can be used to peel off the polyimide film from the resulting laminate. For example, it may be peeled off by hand, or it may be peeled off using mechanical devices such as drive rolls or robots. Furthermore, a method can be employed in which a release layer is provided between the support and the polyimide film, or a method can be employed in which a silicon oxide film is formed on a substrate having numerous grooves, a polyimide film is formed using the silicon oxide film as a base layer, and the polyimide film is peeled off by impregnating the substrate and the silicon oxide film with a silicon oxide etching solution. In addition, a method can be employed in which the polyimide film is separated by irradiation with laser light.

[0095] Furthermore, in a batch-type device manufacturing process in which a polyamic acid composition is applied to a support, heated to imide it, and then the polyimide film is peeled off after forming electronic elements, if the adhesion between the support and the polyimide film is low, the polyimide film may peel off from the support during the electronic element formation process, potentially adversely affecting the formation of the electronic element. In particular, for laminates in which a polyimide film is provided on a support via an inorganic oxide film (e.g., a SiOx film), it is preferable that the adhesion between the inorganic oxide film and the polyimide film is excellent. Here, adhesion refers to adhesion strength. When manufacturing electronic devices using a laminate in which a polyimide film is provided on a support via an inorganic oxide film, from the viewpoint of improving productivity, the peel strength between the polyimide film and the inorganic oxide film is preferably 0.05 N / cm or more, and more preferably 0.10 N / cm or more. In addition, to obtain a laminate with superior heat-resistant adhesion, it is preferable that the post-heat peel strength, described later, is 0.30 N / cm or more.

[0096] The polyamic acid composition and polyimide according to this embodiment may be used as is in coating and molding processes for manufacturing products and components, or they may be used as materials for further coating or other treatments on molded products formed into a film. For use in coating or molding processes, the polyamic acid composition or polyimide may be dissolved or dispersed in an organic solvent as needed, and further, a photocurable component, a thermosetting component, a nonpolymerizable binder resin, and other components may be added as needed to prepare a composition containing a specific polyamic acid or polyimide.

[0097] To impart processing characteristics and various functionalities to the polyamic acid composition and polyimide according to this embodiment, various organic or inorganic low-molecular-weight compounds or high-molecular-weight compounds may be blended into the polyamic acid composition as additives. Examples of additives include dyes, surfactants, leveling agents, plasticizers, silicones, fine particles, sensitizers, etc. Fine particles include organic fine particles made of polystyrene, polytetrafluoroethylene, etc., and inorganic fine particles made of colloidal silica, carbon, layered silicates, etc., and these may have a porous or hollow structure. Furthermore, the function and form of the fine particles are not particularly limited, and for example, they may be pigments, fillers, or fibrous particles.

[0098] Various inorganic thin films, such as metal oxide thin films or transparent electrodes, may be formed on the surface of the polyimide film according to this embodiment. The method for forming these inorganic thin films is not particularly limited and includes, for example, PVD methods such as sputtering, vacuum deposition, and ion plating, as well as CVD methods.

[0099] The polyimide film according to this embodiment is preferable for use in fields and products where these properties are beneficial, as it exhibits heat resistance, low thermal expansion, and low internal stress when forming a laminate with a glass substrate, ensuring adhesion with inorganic materials during high-temperature processes. For example, the polyimide film according to this embodiment is preferable for use in liquid crystal displays, image display devices such as organic EL and electronic paper, printed materials, color filters, flexible displays, optical films, 3D displays, touch panels, transparent conductive film substrates, solar cells, etc., and is even more preferable as a replacement material for parts where glass is currently used. In these applications, the thickness of the polyimide film is, for example, 1 μm to 200 μm, and preferably 3 μm to 100 μm. The thickness of the polyimide film can be measured using a laser hologaze.

[0100] Furthermore, the polyamic acid composition according to this embodiment can be suitably used in a batch-type device manufacturing process in which the polyamic acid composition is applied to a support, heated to imide it, an electronic element is formed, and then the polyimide film is peeled off. Accordingly, this embodiment also includes a method for manufacturing a polyimide film, in which a laminate is obtained by the method for manufacturing a laminate according to this embodiment described above, and then the polyimide film is peeled off from the support. This embodiment also includes a method for manufacturing an electronic device, in which an electronic element is formed on the polyimide film after obtaining a laminate according to the method for manufacturing a laminate according to this embodiment described above.

[0101] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0102] <Preparation of Polyamic Acid Compositions> The preparation methods for polyamic acid compositions P1 to P31 used in the examples and comparative examples are described below. In the following, compounds and reagents are referred to by the following abbreviations. Furthermore, the preparation of polyamic acid compositions P1 to P31 was carried out under a nitrogen atmosphere. NMP: N-methyl-2-pyrrolidone PDA: p-phenylenediamine 4,4'-ODA: 4,4'-oxydianiline 3,4'-ODA: 3,4'-oxydianiline TPE-R: 1,3-bis(4-aminophenoxy)benzene 4-BAAB: 4-aminophenyl-4-aminobenzoate PAM-E: 1,3-bis(3-aminopropyl)tetramethyldisiloxane BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride ODPA: 4,4'-oxydiphthalic acid anhydride 2PhI: 2-phenylimidazole

[0103] [Preparation of Polyamic Acid Composition P1] 85.0 g of NMP was placed in a 500 mL glass separable flask equipped with a stirrer fitted with a stainless steel stirring rod and a nitrogen inlet tube, as the organic solvent for polymerization. Then, under an atmosphere of 23°C, 3.870 g of PDA, 0.260 g of 4,4'-ODA, and 0.018 g of PAM-E were added to the flask and dissolved while stirring the contents. Then, under an atmosphere of 23°C, 10.852 g of BPDA was added to the contents of the flask while stirring the contents. Finally, under an atmosphere of 85°C, the contents of the flask were stirred for 3 hours to obtain polyamic acid composition P1.

[0104] [Preparation of Polyamic Acid Composition P2] A polyamic acid composition was prepared in the same manner as polyamic acid composition P1. Then, 2PhI was added to the obtained polyamic acid composition to obtain polyamic acid composition P2. The amount of 2PhI added was 0.3 parts by weight per 100 parts by weight of polyamic acid.

[0105] [Preparation of Polyamic Acid Compositions P3, P5-P8 and P10-31] Polyamic acid compositions P3, P5-P8 and P10-31 were obtained in the same manner as polyamic acid composition P1, except that the acidic dianhydrides used and their charging ratios, and the diamines used and their charging ratios were as shown in Tables 1 and 2. In all of the polyamic acid compositions P3, P5-P8 and P10-31, the total amount of substance of the acidic dianhydrides was the same as the total amount of substance of the acidic dianhydrides in polyamic acid composition P1. Also, in all of the polyamic acid compositions P3, P5-P8 and P10-31, the total amount of substance of the diamines was the same as the total amount of substance of the diamines in polyamic acid composition P1.

[0106] [Preparation of Polyamic Acid Compositions P4 and P9] Polyamic acid compositions P4 and P9 were obtained in the same manner as polyamic acid composition P2, except that the acidic dianhydride used and its charging ratio, and the diamine used and its charging ratio were as shown in Table 1. In both polyamic acid compositions P4 and P9, the total amount of substance of the acidic dianhydride was the same as the total amount of substance of the acidic dianhydride in polyamic acid composition P2. In addition, in both polyamic acid compositions P4 and P9, the total amount of substance of the diamine was the same as the total amount of substance of the diamine in polyamic acid composition P2.

[0107] Tables 1 and 2 show the acidic dianhydrides used and their proportions, the diamines used and their proportions, the amount of 2PhI added, and the SAC and SDA residue content for polyamic acid compositions P1 to P31. In Tables 1 and 2, "-" means that the component was not used. In Tables 1 and 2, the values ​​in the "Acidic Dianhydride" column represent the content of each acidic dianhydride relative to the total amount of diamine used (100 mol%) (unit: mol%). In Tables 1 and 2, the values ​​in the "Diamine" column represent the content of each diamine relative to the total amount of diamine used (100 mol%) (unit: mol%). In Tables 1 and 2, the values ​​in the "2PhI" column represent the amount of 2PhI relative to 100 parts by weight of the synthesized polyamic acid (unit: parts by weight). Furthermore, for all of the polyamic acid compositions P1 to P31, the mole fraction of each residue of polyamic acid in the prepared polyamic acid composition was consistent with the mole fraction of each monomer (each monomer corresponding to each residue) used in the synthesis of the polyamic acid.

[0108]

[0109]

[0110] <Preparation of Polyimide Films> The following describes the methods for preparing the polyimide films (laminated structures) of Examples 1 to 18 and Comparative Examples 1 to 13.

[0111] [Example 1] A SiOx film (thickness: 600 nm) was laminated onto a Corning glass substrate (product name: Eagle XG, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm) by plasma CVD. Then, a polyamic acid composition P1 was applied to the SiOx film using a spin coater to obtain a laminate. The obtained laminate was heated in air at 120°C for 30 minutes, and then heated in a nitrogen atmosphere from 23°C to 460°C at a heating rate of 7°C / min. After the atmosphere temperature reached 460°C, the laminate was heated at 460°C for 10 minutes to obtain a laminate (laminated in Example 1) in which the glass substrate, SiOx film, and polyimide film (thickness: 6 μm) were laminated in this order.

[0112] [Examples 2-18 and Comparative Examples 1-13] Laminates of Examples 2-18 and Comparative Examples 1-13 were obtained by the same method as in Example 1, except that the polyamic acid compositions shown in Table 3 were used instead of polyamic acid composition P1.

[0113] <Method for Measuring Peel Strength> [Post-Film Peel Strength] In accordance with the ASTM D1876-01 standard, a 10 mm wide cut was made in the polyimide film of each laminate obtained by the above procedure using a utility knife. Then, each laminate was left to stand for 24 hours in an environment of 23°C and 55% relative humidity to obtain a sample for measurement. Next, the average value of the peel strength was measured when the polyimide film was peeled off by 50 mm under the conditions of a temperature of 23°C and 55% relative humidity, at a tensile speed of 50 mm / min and a peeling angle of 90°, using a tensile testing machine (Strograph VES1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The obtained value was defined as the post-film peel strength.

[0114] [Peel Strength After Heating] In accordance with the ASTM D1876-01 standard, 10 mm wide cuts were made in the polyimide film of each laminate obtained by the above procedure using a utility knife. Then, each laminate was heated in a nitrogen atmosphere at a temperature of 470°C for 90 minutes. Next, each heated laminate was left to stand for 24 hours in an environment of 23°C and 55% relative humidity to obtain a sample for measurement. Next, the average peel strength of the obtained sample was measured using a tensile testing machine (Strograph VES1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.) when the polyimide film was peeled off by 50 mm under conditions of 23°C and 55% relative humidity, at a tensile speed of 50 mm / min and a peeling angle of 90°. The obtained value was defined as the peel strength after heating. If the peel strength after heating was 0.30 N / cm or higher, it was evaluated as having "excellent heat resistance and adhesion". On the other hand, if the peel strength after heating was less than 0.30 N / cm, it was evaluated as "not having good heat resistance and adhesion."

[0115] <Method for measuring internal stress> A Corning glass substrate (product name: Eagle XG, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm x 100 mm), whose warpage had been measured in advance, was coated with each polyamic acid composition obtained in the above procedure using a spin coater to obtain a laminate. The obtained laminate was heated in air at 120°C for 30 minutes, and then heated in a nitrogen atmosphere from 23°C to 460°C at a heating rate of 7°C / min. After the atmosphere temperature reached 460°C, the laminate was heated at 460°C for 10 minutes to obtain a laminate with a 10 μm thick polyimide film on the glass substrate. To eliminate the effect of water absorption by the polyimide film, the laminate was dried at 120°C for 10 minutes, and then the warpage of the laminate in a nitrogen atmosphere at 25°C was measured using a thin-film stress measuring device (FLX-2320-S, manufactured by KLA-Tencor). Then, using Stoney's formula, the internal stress generated between the glass substrate and the polyimide film was calculated from the amount of warpage of the glass substrate before polyimide film formation and the amount of warpage of the laminate. If the internal stress was 10 MPa or less, it was evaluated as "the internal stress has been reduced." On the other hand, if the internal stress exceeded 10 MPa, it was evaluated as "the internal stress has not been reduced."

[0116] <Results> Table 3 shows the polyamic acid compositions used, post-film formation peel strength, post-heat peel strength, and internal stress for Examples 1 to 18 and Comparative Examples 1 to 13. In Table 3, "Not Measurable" means that delamination occurred between the SiOx film and the polyimide film during film formation, and the peel strength could not be measured. Also in Table 3, "-" in the columns for post-film formation peel strength and post-heat peel strength means that the adhesion between the SiOx film and the polyimide film was too high, and the polyimide film could not be peeled off when measuring the peel strength. Also in Table 3, "-" in the column for internal stress means that it was not measured.

[0117]

[0118] The polyamic acid contained in the polyamic acid compositions used in Examples 1 to 18 had an SDA residue content of 0.01 mol% to 0.40 mol%. The polyamic acid contained in the polyamic acid compositions used in Examples 1 to 18 had an SAC residue content of 0.5 mol% to 5.0 mol%.

[0119] As shown in Table 3, the post-heat peel strength was 0.30 N / cm or higher in Examples 1 to 18. Therefore, the laminates obtained using the polyamic acid in Examples 1 to 18 exhibited excellent heat-resistant adhesion. In Examples 1 to 18, the internal stress was 10 MPa or less. Therefore, the laminates obtained using the polyamic acid in Examples 1 to 18 were able to reduce internal stress.

[0120] The polyamic acid contained in the polyamic acid compositions used in Comparative Examples 1-4 and 8-11 did not contain specific aromatic compound residues. The polyamic acid contained in the polyamic acid compositions used in Comparative Examples 5 and 13 had an SAC residue content exceeding 5.0 mol%. The polyamic acid contained in the polyamic acid composition used in Comparative Example 6 had an SDA residue content exceeding 0.40 mol%. The polyamic acid contained in the polyamic acid compositions used in Comparative Examples 7 and 12 did not contain siloxanediamine residues.

[0121] As shown in Table 3, in Comparative Examples 1-4, 6, and 8-12, the peel strength after heating was less than 0.30 N / cm. Therefore, the laminates obtained using the polyamic acid in Comparative Examples 1-4, 6, and 8-12 did not have excellent heat-resistant adhesion. In Comparative Example 7, delamination occurred between the SiOx film and the polyimide film during film formation, making it impossible to measure the peel strength. In Comparative Examples 5 and 13, the internal stress exceeded 10 MPa. Therefore, the laminates obtained using the polyamic acid in Comparative Examples 5 and 13 failed to reduce the internal stress.

[0122] The results above demonstrate that the present invention provides a polyamic acid capable of producing polyimides with excellent heat resistance and adhesion while reducing internal stress.

Claims

1. A polyamic acid having a tetracarboxylic dianhydride residue and a diamine residue, wherein the tetracarboxylic dianhydride residue comprises a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue, the diamine residue comprises a p-phenylenediamine residue and a siloxanediamine residue, at least one of the tetracarboxylic dianhydride residue and the diamine residue further comprises a residue derived from a compound in which a plurality of aromatic rings are linked via a linking group, the linking group is one or more selected from the group consisting of an ether group and an ester group, the content of the siloxanediamine residue is 0.01 mol% or more and 0.40 mol% or less with respect to 100 mol% of the total amount of the tetracarboxylic dianhydride residue and the total amount of the diamine residue, and the content of the residue derived from a compound in which a plurality of aromatic rings are linked via a linking group is 0.5 mol% or more and 5.0 mol% or less with respect to 100 mol% of the total amount of the tetracarboxylic dianhydride residue and the total amount of the diamine residue.

2. The polyamic acid according to claim 1, wherein the residue derived from the compound in which the plurality of aromatic rings are linked via a linking group is one or more selected from the group consisting of a tetravalent organic group represented by the following chemical formula (1), a tetravalent organic group represented by the following chemical formula (2), a divalent organic group represented by the following chemical formula (3), a divalent organic group represented by the following chemical formula (4), a divalent organic group represented by the following chemical formula (5), a tetravalent organic group represented by the following chemical formula (6), and a divalent organic group represented by the following chemical formula (7).

3. The polyamic acid according to claim 1, wherein the siloxanediamine residue is a divalent organic group represented by the following general formula (8). (In the above general formula (8), R １ and R ２ Each of these independently represents a divalent hydrocarbon group, and n represents an integer between 1 and 5.

4. A polyamic acid composition comprising the polyamic acid described in claim 1 and an organic solvent.

5. The polyamic acid composition according to claim 4, further comprising one or more compounds selected from the group consisting of imidazole compounds and phosphorus-containing compounds.

6. The polyamic acid composition according to claim 5, wherein the amount of one or more compounds selected from the group consisting of the imidazole compounds and phosphorus-containing compounds is 0.1 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the polyamic acid.

7. A polyimide which is an imidide of a polyamic acid according to claim 1.

8. A polyimide film comprising the polyimide described in claim 7.

9. A laminate having a support and a polyimide film according to claim 8.

10. The laminate according to claim 9, further comprising an inorganic oxide film interposed between the support and the polyimide film, wherein the polyimide film and the inorganic oxide film are in contact.

11. A method for producing a laminate having a support and a polyimide film, comprising: applying the polyamic acid composition described in claim 4 onto the support to form a coating film containing the polyamic acid; and heating the coating film to imide the polyamic acid.

12. An electronic device having a polyimide film according to claim 8 and an electronic element disposed on the polyimide film.

Images