Release layer-forming composition and release layer

Abstract

As a release layer-forming composition for forming a release layer which can be released without causing damage to a resin substrate of a flexible electronic device, provided is a release layer-forming composition that contains an organic solvent and a poly(amic acid) obtained by reacting an aromatic diamine having an alkylene group with 1-20 carbon atoms in a main chain segment with an aromatic tetracarboxylic acid dianhydride. Also provided is a layered product in which a base material, a release layer, and a resin substrate are layered in the stated order, and which is characterized in that the release layer has higher adhesion to the base material than to the resin substrate.

Description

Release layer-forming composition and release layer

[0001] The present invention relates to a composition for forming a release layer and a release layer.

[0002] In recent years, electronic devices have been required to have properties such as flexibility, thinness, and lightness. This has led to a demand for lightweight, flexible plastic substrates to replace the conventional heavy, fragile, and inflexible glass substrates. In particular, new-generation displays require the development of active-matrix full-color TFT display panels using lightweight, flexible plastic substrates (hereinafter referred to as "resin substrates"). It is expected that the technology related to these new-generation displays will be applicable to a variety of fields, including flexible displays, flexible smartphones, and mirror displays.

[0003] Therefore, various methods for manufacturing electronic devices using resin films as substrates have begun to be studied, and for new generation displays, studies are underway to manufacture them using processes that allow the use of existing TFT equipment. For example, Patent Documents 1, 2, and 3 disclose a method in which an amorphous silicon thin film layer is formed on a glass substrate, a plastic substrate is formed on the thin film layer, and then a laser is irradiated from the glass surface side to peel the plastic substrate from the glass substrate by hydrogen gas generated as the amorphous silicon crystallizes.

[0004] Furthermore, Patent Document 4 discloses a method for completing a liquid crystal display device by attaching a peelable layer (referred to as a "transferable layer" in Patent Document 4) to a plastic film using the techniques disclosed in Patent Documents 1 to 3.

[0005] However, the methods disclosed in Patent Documents 1 to 4, and particularly the method disclosed in Patent Document 4, have problems such as the necessity of using a highly light-transmitting substrate to transmit the laser light, the need for irradiation with a laser light of a relatively high energy sufficient to pass through the substrate and further release hydrogen contained in the amorphous silicon, and the possibility that the laser light irradiation may damage the layer to be peeled. Moreover, when the peeling layer has a large area, the laser treatment takes a long time, making it difficult to improve the productivity of device fabrication.

[0006] JP-A-10-125929 JP-A-10-125931 International Publication No. 2005 / 050754 JP-A-10-125930

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a composition for forming a release layer that can be peeled off without damaging the resin substrate of a flexible electronic device, and the release layer.

[0008] As a result of extensive research to solve the above-mentioned problems, the inventors discovered that in the manufacture of resin substrates, a release layer formed on a base can be obtained by using a release layer-forming composition containing a polyamic acid having a specific structure and an organic solvent, resulting in a release layer that has excellent adhesion to the base, as well as moderate adhesion and moderate release properties with resin substrates used as flexible electronic devices, and thus completed the present invention.

[0009] That is, the present invention provides: 1. a composition for forming a release layer, comprising a polyamic acid obtained by reacting an aromatic diamine having an alkylene group having 1 to 20 carbon atoms in the main chain portion with an aromatic tetracarboxylic dianhydride, and an organic solvent; 2. the composition for forming a release layer according to 1 above, wherein the polyamic acid has at least a structural unit represented by the following formula (1); (wherein Ar1 represents a divalent organic group having an alkylene group having 1 to 20 carbon atoms and an aromatic group, and Ar2 represents a tetravalent organic group having an aromatic group.) 3. The composition for forming a release layer according to 2 above, wherein Ar1 in the above formula (1) is a divalent organic group represented by the following formula (2): (wherein X represents an alkylene group having 1 to 20 carbon atoms; Y1 and Y2 may be the same or different and represent a single bond, an ether bond, a carbonyl bond, an ester bond, an amide bond, a urethane bond, a urea bond, a thioether bond, or a sulfonyl bond; R1 and R2 each independently represent a halogen atom or an alkyl group having 1 to 4 carbon atoms; n1 and n2 each independently represent an integer of 0 to 4; * represents a bond.) 4. A composition for forming a release layer according to 3 above, wherein Y1 and Y2 in the above formula (2) may be the same or different and represent a single bond or an ether bond; 5. A composition for forming a release layer according to any one of 1 to 4 above, wherein the content of the aromatic diamine having an alkylene group having 1 to 20 carbon atoms in the main chain portion is 50 to 100 mol % of all diamine components; 6. 6. The composition for forming a release layer according to any one of 1 to 5 above, wherein the polyamic acid is a polyamic acid represented by the following formula (3) in which both ends are capped with an aromatic monoamine, or a polyamic acid represented by the following formula (4) in which both ends are capped with an aromatic dicarboxylic acid. (wherein Ar1 represents a divalent organic group having an alkylene group and an aromatic group in the main chain portion, and Ar2 represents a tetravalent organic group having an aromatic group. Ar3 and Ar4 each independently represent an aromatic group having 6 to 30 carbon atoms, which may have a halogen atom, an alkyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 20 carbon atoms.) 7. A release layer-forming composition according to 6 above, wherein Ar3 or Ar4 is an optionally substituted benzene ring or naphthalene ring; 8. A release layer obtained from a release layer-forming composition according to any one of 1 to 7 above; 9. A release layer manufacturing method comprising a step of baking a release layer-forming composition according to any one of 1 to 7 above at a maximum temperature of less than 400°C; 10. A laminate comprising a substrate, the release layer according to 8 above, and a resin substrate laminated in this order, wherein the release layer has greater adhesion to the substrate than to the resin substrate; 11. The present invention provides: 1. a method for producing a flexible electronic device provided with a resin substrate, characterized by using the release layer described in 8 above; 12. a method for producing a flexible electronic device, comprising the steps of applying a composition for forming a resin substrate onto the release layer described in 8 above, and then baking the composition at a maximum temperature of less than 400°C to form a resin substrate; and 13. a production method described in 11 or 12 above, in which the resin substrate is a substrate made of a free-standing film.

[0010] By using the release layer-forming composition of the present invention, it is possible to reproducibly obtain a release layer that has excellent adhesion to the substrate, moderate adhesion to the resin substrate, and moderate release properties. By using the release layer-forming composition of the present invention, it is possible to separate the resin substrate together with the circuits formed thereon from the substrate in the manufacturing process of a flexible electronic device without damaging the resin substrate formed on the substrate or the circuits formed thereon. Therefore, the release layer-forming composition of the present invention can contribute to simplifying the manufacturing process of flexible electronic devices equipped with resin substrates and improving their yield.

[0011] The present invention provides a release layer-forming composition comprising a polyamic acid obtained by reacting an aromatic diamine having an alkylene group having 1 to 20 carbon atoms in the main chain with an aromatic tetracarboxylic dianhydride, and an organic solvent.

[0012] The polyamic acid is preferably a polyamic acid having at least a structural unit represented by the following formula (1): (In the formula, Ar1 represents a divalent organic group having an alkylene group having 1 to 20 carbon atoms and an aromatic group, and Ar2 represents a tetravalent organic group having an aromatic group.)

[0013] The above Ar1 is preferably a divalent organic group represented by the following formula (2). (In the formula, X represents an alkylene group having 1 to 20 carbon atoms; Y1 and Y2 may be the same or different and represent a single bond, an ether bond, a carbonyl bond, an ester bond, an amide bond, a urethane bond, a urea bond, a thioether bond, or a sulfonyl bond; R1 and R2 each independently represent a halogen atom or an alkyl group having 1 to 4 carbon atoms; n1 and n2 each independently represent an integer of 0 to 4; and * represents a bond.)

[0014] The alkylene group having 1 to 20 carbon atoms may be either linear or branched, and specific examples thereof include methylene, ethylene, propylene, trimethylene, tetramethylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, nonadecylene, and eicosanylene groups, but are not limited to these. In the present invention, alkylene groups having 2 to 6 carbon atoms are preferred, and linear alkylene groups having 2 to 6 carbon atoms are more preferred.

[0015] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0016] The alkyl group having 1 to 4 carbon atoms may be either linear or branched, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group.

[0017] The above Ar2 is preferably an aromatic group containing 1 to 5 benzene rings. The above Ar2 may contain either an ester bond or an ether bond, or both.

[0018] The polyamic acid represented by the above formula (1) can be obtained by reacting an aromatic tetracarboxylic dianhydride with an aromatic diamine having a structure in which benzene rings having amino groups are bonded to both ends of an alkylene group having 1 to 20 carbon atoms. The aromatic tetracarboxylic dianhydrides and aromatic diamines that can be used to synthesize the polyamic acid represented by the above formula (1) will be described in detail below.

[0019] In the present invention, the aromatic tetracarboxylic acid dianhydride is not particularly limited as long as it has an aromatic group and two dicarboxylic acid anhydride moieties in the molecule, but an aromatic tetracarboxylic acid dianhydride containing 1 to 5 benzene rings is preferred.

[0020] Specific examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, naphthalene-1,2,3,4-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, naphthalene-1,2,7,8-tetracarboxylic dianhydride, naphthalene-2,3,5,6-tetracarboxylic dianhydride, and naphthalene-2,3 ,6,7-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, biphenyl-2,2',3,3'-tetracarboxylic dianhydride, biphenyl-2,3,3',4'-tetracarboxylic dianhydride, biphenyl-3,3',4,4'-tetracarboxylic dianhydride, anthracene-1,2,3,4-tetracarboxylic dianhydride, anthracene-1,2,5,6-tetracarboxylic dianhydride, anthracene-1,2,6,7-tetracarboxylic dianhydride Carboxylic acid dianhydrides, anthracene-1,2,7,8-tetracarboxylic acid dianhydride, anthracene-2,3,6,7-tetracarboxylic acid dianhydride, phenanthrene-1,2,3,4-tetracarboxylic acid dianhydride, phenanthrene-1,2,5,6-tetracarboxylic acid dianhydride, phenanthrene-1,2,6,7-tetracarboxylic acid dianhydride, phenanthrene-1,2,7,8-tetracarboxylic acid dianhydride, phenanthrene-1,2,9,10-tetracarboxylic acid Examples of the dianhydride include, but are not limited to, tetracarboxylic acid dianhydrides, phenanthrene-2,3,5,6-tetracarboxylic acid dianhydride, phenanthrene-2,3,6,7-tetracarboxylic acid dianhydride, phenanthrene-2,3,9,10-tetracarboxylic acid dianhydride, phenanthrene-3,4,5,6-tetracarboxylic acid dianhydride, phenanthrene-3,4,9,10-tetracarboxylic acid dianhydride, and aromatic tetracarboxylic acid dianhydrides represented by the following formulas (B1) to (B12). These may be used alone or in combination of two or more.

[0021]

[0022] In the present invention, the diamine is not particularly limited as long as it is an aromatic diamine that provides an alkylene group having 1 to 20 carbon atoms in the main chain portion, but a diamine having a structure of the following formula (A1) is preferred. (In the formula, X represents an alkylene group having 1 to 20 carbon atoms; Y1 and Y2 may be the same or different and represent a single bond, an ether bond, a carbonyl bond, an ester bond, an amide bond, a urethane bond, a urea bond, a thioether bond, or a sulfonyl bond; R1 and R2 each independently represent a halogen atom or an alkyl group having 1 to 4 carbon atoms; and n1 and n2 each independently represent an integer of 0 to 4.)

[0023] Specific examples of the alkylene group having 1 to 20 carbon atoms, the halogen atom, and the alkyl group having 1 to 4 carbon atoms are the same as those exemplified above.

[0024] Specific examples of the diamine include the following diamines.

[0025] In the polyamic acid, the content of the aromatic diamine having an alkylene group having 1 to 20 carbon atoms in the main chain is preferably 50 to 100 mol % of the total diamine components.

[0026] The weight-average molecular weight of the polyamic acid having a monomer unit represented by formula (1) used in the present invention is preferably at least 3,000, more preferably at least 5,000, and even more preferably at least 10,000. On the other hand, the upper limit of the weight-average molecular weight of the polyamic acid used in the present invention is usually at most 2,000,000, but in consideration of preventing the viscosity of the resin composition from becoming excessively high and obtaining a highly flexible resin thin film with good reproducibility, the upper limit is preferably at most 1,000,000, and more preferably at most 200,000.

[0027] The polyamic acid used in the present invention preferably contains 50 mol % or more, more preferably 60 mol % or more, even more preferably 70 mol % or more, even more preferably 80 mol % or more, and most preferably 90 mol % or more of the monomer unit represented by formula (1). By using a polyamic acid having such a content of monomer units, a resin thin film having properties suitable for a release film can be obtained with good reproducibility.

[0028] According to a preferred embodiment of the present invention, the polyamic acid contained in the release layer-forming composition of the present invention is a polymer consisting only of monomer units represented by formula (1), i.e., a polymer containing 100 mol% of monomer units represented by formula (1). In this case, the monomer units in such a polyamic acid may be of one specific type or may be of two or more types, as long as they are represented by formula (1). In the latter case, the number of monomer units of formula (1) contained in the polyamic acid is preferably 2 to 4, more preferably 2 to 3.

[0029] The polyamic acid used in the present invention may contain other monomer units in addition to the monomer unit represented by formula (1). The content of such other monomer units must be less than 50 mol%, preferably less than 40 mol%, more preferably less than 30 mol%, even more preferably less than 20 mol%, and even more preferably less than 10 mol%.

[0030] Such other monomer units include, for example, monomer units of formula (e).

[0031] In formula (e), X 1 represents a tetravalent organic group derived from a tetracarboxylic dianhydride, Y a represents a divalent organic group derived from a diamine, and m represents a natural number.

[0032] Diamines that provide such other monomer units include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2-methyl-1,4-phenylenediamine, 5-methyl-1,3-phenylenediamine, 4-methyl-1,3-phenylenediamine, 2-(trifluoromethyl)-1,4-phenylenediamine, 2-(trifluoromethyl)-1,3-phenylenediamine and 4-(trifluoromethyl)-1,3-phenylenediamine, benzidine, 2,2'-dimethylbenzidine Benzidine, 3,3'-dimethylbenzidine, 2,3'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, 2,3'-bis(trifluoromethyl)benzidine, 4,4'-diaminophenyl ether, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminobenzanilide, 5-amino-2-(3-aminophenyl)-1H-benzimidazole, 9,9-bis(4-aminophenyl)fluorene, and the like.

[0033] Examples of the tetracarboxylic dianhydride include aromatic tetracarboxylic acids such as pyromellitic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-diphenylethertetracarboxylic acid, 3,3',4,4'-diphenylsulfonetetracarboxylic acid, and 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid, dianhydrides thereof, and derivatives thereof; 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid, and 1, Examples of the compound include alicyclic tetracarboxylic acids such as 2,3,4-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid, 2,3,5-tricarboxy-2-cyclopentaneacetic acid, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid, 2,3,4,5-tetrahydrofurantetracarboxylic acid, and 3,5,6-tricarboxy-2-norbornaneacetic acid, dianhydrides thereof, and derivatives thereof, as well as aliphatic tetracarboxylic acids such as 1,2,3,4-butanetetracarboxylic acid, dianhydrides thereof, and derivatives thereof. Further examples include compounds having a trifluoromethyl group or a hexafluoroisopropylidene group, such as 2,2-bis(3,4-dicarboxyphenyl)hexafluoroisopropylidene, 4,4'-hexafluoroisopropylidene diphthalic acid, dianhydrides thereof, and derivatives thereof, but are not limited to these compounds. Furthermore, the tetracarboxylic acid dianhydride may be one or a combination of two or more compounds selected from tetracarboxylic acids and derivatives thereof.

[0034] According to a preferred embodiment of the present invention, the polyamic acid used in the present invention can be obtained by reacting an aromatic tetracarboxylic acid dianhydride as the acid dianhydride with a diamine component containing a diamine represented by formula (A1).

[0035] In the above reaction, the molar ratio of the aromatic tetracarboxylic dianhydride to the diamine component containing the diamine represented by Formula (A1) can be appropriately set taking into consideration the molecular weight of the desired polyamic acid, the proportion of monomer units, etc., and is typically about 0.7 to 1.3, and preferably about 0.8 to 1.2, of the tetracarboxylic dianhydride component relative to the diamine component per 1. When producing an amine-terminated polyamic acid, it is sufficient to select within the above range a ratio of the tetracarboxylic dianhydride component relative to the diamine component per 1 being less than 1, and when producing a carboxylic acid-terminated polyamic acid, it is sufficient to select within the above range a ratio of the tetracarboxylic dianhydride component relative to the diamine component per 1 being greater than 1.

[0036] The organic solvent used in the above-mentioned reaction is not particularly limited as long as it does not adversely affect the reaction, and specific examples include m-cresol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropylamide, 3-ethoxy-N,N-dimethylpropylamide, 3-propoxy-N,N-dimethylpropylamide, 3-isopropoxy-N,N-dimethylpropylamide, 3-butoxy-N,N-dimethylpropylamide, 3-sec-butoxy-N,N-dimethylpropylamide, 3-tert-butoxy-N,N-dimethylpropylamide, γ-butyrolactone, etc. The organic solvents may be used alone or in combination of two or more.

[0037] In particular, the organic solvent used in the reaction is preferably at least one selected from the group consisting of amides represented by formula (S1), amides represented by formula (S2), and amides represented by formula (S3), because it dissolves the above-mentioned diamines, tetracarboxylic dianhydrides, dicarboxylic acids, polyamic acids, and polyamides well.

[0038] In the formula, R 1 and R 2 R each independently represents an alkyl group having 1 to 10 carbon atoms. 3represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. h represents a natural number, preferably 1 to 3, and more preferably 1 or 2.

[0039] Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a s-butyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, etc. Among these, an alkyl group having 1 to 3 carbon atoms is preferred, and an alkyl group having 1 or 2 carbon atoms is more preferred.

[0040] The reaction temperature may be set appropriately within the range from the melting point to the boiling point of the solvent used, and is usually about 0 to 100° C. However, in order to prevent imidization of the resulting polyamic acid and maintain a high content of polyamic acid units, the temperature is preferably about 0 to 70° C., more preferably about 0 to 60° C., and even more preferably about 0 to 50° C. The reaction time cannot be generally determined because it depends on the reaction temperature and the reactivity of the raw materials, but is usually about 1 to 100 hours.

[0041] Among the polyamic acids obtained by reacting the tetracarboxylic dianhydride component and the diamine component described above, the polyamic acid having carboxylic acid groups at both molecular chain terminals can be further reacted with an aromatic monoamine to obtain the amine-capped polyamic acid contained in the release layer-forming composition of the present invention. The aromatic monoamine used to cap both molecular chain terminals preferably has an aromatic ring containing 6 to 30 carbon atoms, more preferably an aromatic ring containing 6 to 15 carbon atoms, and even more preferably an aromatic ring containing 6 to 10 carbon atoms.

[0042] Specific examples of aromatic monoamines include aniline, 1-naphthylamine, 2-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 9-aminoanthracene, 9-aminophenanthracene, 2-aminobiphenyl, 3-aminobiphenyl, and 4-aminobiphenyl. Among these, aniline is particularly suitable in the present invention in consideration of safety, ease of handling, reactivity, and the like.

[0043] From the viewpoint of reliably capping both molecular chain terminals of the polyamic acid obtained by reacting the tetracarboxylic dianhydride component with the diamine component, the amount of aromatic monoamine charged is preferably 2 moles or more, more preferably 2 to 4 moles, and even more preferably 2 to 3 moles, per mole of the polyamic acid. The amount of aromatic monoamine added during actual synthesis may be preferably 0.1 moles or more, more preferably 0.2 to 4 moles, and even more preferably 0.2 to 3 moles, per mole of the tetracarboxylic dianhydride used in the synthesis of the polyamic acid.

[0044] Furthermore, among the polyamic acids obtained by reacting the tetracarboxylic dianhydride component and diamine component described above, the polyamic acid having amino groups at both ends of the molecular chain can be further reacted with an aromatic dicarboxylic acid to obtain the amine-capped polyamic acid contained in the release layer-forming composition of the present invention.

[0045] The aromatic dicarboxylic acid or aromatic dicarboxylic anhydride used to cap both molecular chain terminals preferably has an aromatic ring having 6 to 30 carbon atoms, more preferably has an aromatic ring having 6 to 15 carbon atoms, and even more preferably has an aromatic ring having 6 to 10 carbon atoms.

[0046] Specific examples of aromatic dicarboxylic acids or aromatic dicarboxylic anhydrides include o-phthalic acid, isophthalic acid, terephthalic acid, 5-methylisophthalic acid, 5-tert-butylisophthalic acid, 5-aminoisophthalic acid, 5-hydroxyisophthalic acid, 2,5-dimethylterephthalic acid, tetramethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 1,4-anthracene dicarboxylic acid. carboxylic acid, 1,4-anthraquinone dicarboxylic acid, 2,5-biphenyl dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, 1,5-biphenylenedicarboxylic acid, 4,4"-terphenyl dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid, 4,4'-diphenylethane dicarboxylic acid, 4,4'-diphenylpropane dicarboxylic acid, 4,4'-diphenylhexafluoropropane dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-bibenzyl dicarboxylic acid acid, 4,4'-stilbene dicarboxylic acid, 4,4'-transicarboxylic acid, 4,4'-carbonyldibenzoic acid, 4,4'-sulfonyldibenzoic acid, 4,4'-dithiodibenzoic acid, p-phenylenediacetic acid, 3,3'-p-phenylenedipropionic acid, 4-carboxycinnamic acid, p-phenylenediacrylic acid, 3,3'-[4,4'-(methylenedi-p-phenylene)]dipropionic acid, 4,4'-[4,4'-(oxydi-p-phenylene)]dipropionic acid, 4,4'-[4 ,4'-(oxydi-p-phenylene)]dibutyric acid, (isopropylidenedi-p-phenylenedioxy)dibutyric acid, and bis(p-carboxyphenyl)dimethylsilane; and aromatic dicarboxylic acid anhydrides such as phthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, and 1,8-naphthalenedicarboxylic anhydride. Among these, phthalic anhydride is particularly preferred in the present invention, taking into consideration safety, ease of handling, reactivity, and the like.

[0047] The organic solvent used for blocking both ends of the molecular chain of the polyamic acid and the reaction temperature for blocking both ends of the molecular chain of the polyamic acid are the same as those used for the reaction between the acid dianhydride and the diamine component.

[0048] The polyamic acid having both ends capped with an aromatic monoamine is preferably one represented by the following formula (3).

[0049] The polyamic acid having both ends blocked with an aromatic dicarboxylic acid is preferably one represented by the following formula (4).

[0050] In formulas (3) and (4), Ar1 represents a divalent organic group having an alkylene group and an aromatic group having 1 to 20 carbon atoms in the main chain portion, and Ar2 represents a tetravalent organic group having an aromatic group. Ar3 and Ar4 each independently represent an aromatic group having 6 to 30 carbon atoms, which may have a halogen atom, an alkyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

[0051] By the method described above, a reaction solution containing the target polyamic acid can be obtained.

[0052] In the present invention, after filtering the reaction solution, the filtrate can be used as it is, or the solution obtained by diluting or concentrating it can be used as the composition for forming a release layer of the present invention. By doing so, not only can the inclusion of impurities that may cause deterioration in the adhesion, releasability, etc. of the resulting release layer be reduced, but also the composition for forming a release layer can be obtained efficiently. The solvent used for dilution or concentration is not particularly limited, and examples thereof include the same as the specific examples of the reaction solvents used in the above reaction. They may be used alone or in combination of two or more.

[0053] Among the above specific examples, in consideration of obtaining a highly flat resin thin film with good reproducibility, the following solvents are preferred: N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone, γ-butyrolactone, ethyl lactate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cycloheptane, cyclohexane, diethylene glycol ethyl methyl ether, and ethylene glycol.

[0054] The concentration of polyamic acid relative to the total mass of the composition for forming the release layer is set appropriately taking into consideration the thickness of the thin film (release layer) to be produced, the viscosity of the composition, etc., but is usually about 0.5 to 30 mass %, preferably about 5 to 25 mass %.

[0055] The viscosity of the release layer-forming composition is appropriately set taking into consideration the thickness of the thin film to be produced, etc. However, particularly when the goal is to reproducibly obtain a resin thin film having a thickness of about 0.05 to 5 μm, the viscosity is typically about 3 to 10,000 mPa·s at 25°C, preferably about 5 to 1,000 mPa·s, and more preferably about 8 to 200 mPa·s. Here, the viscosity can be measured using a commercially available viscometer for measuring the viscosity of liquids, for example, with reference to the procedure described in JIS K7117-2, at a composition temperature of 25°C. Preferably, a cone-plate type rotational viscometer is used as the viscometer, preferably using a 1°34' x R24 standard cone rotor, and the viscosity can be measured at a composition temperature of 25°C. An example of such a rotational viscometer is the TVE-25H manufactured by Toki Sangyo Co., Ltd.

[0056] The release layer-forming composition according to the present invention may contain various components in addition to the polyamic acid and the organic solvent, such as, but not limited to, a crosslinking agent (hereinafter also referred to as a crosslinkable compound).

[0057] Examples of the crosslinkable compound include, but are not limited to, compounds containing two or more epoxy groups, melamine derivatives, benzoguanamine derivatives, and glycolurils having a group in which the hydrogen atom of an amino group is substituted with a methylol group, an alkoxymethyl group, or both.

[0058] Specific examples of crosslinkable compounds include, but are not limited to, the following: Compounds containing two or more epoxy groups include epoxy compounds having a cyclohexene structure such as Epolead GT-401, Epolead GT-403, Epolead GT-301, Epolead GT-302, Celloxide 2021, and Celloxide 3000 (all manufactured by Daicel Corporation); Epicoat 1001, Epicoat 1002, Epicoat 1003, Epicoat 1004, Epicoat 1007, Epicoat 1009, Epicoat 1010, and Epicoat 828 (all manufactured by Japan Epoxy Resins); bisphenol A type epoxy compounds such as Epikote 807 (Japan Epoxy Resins Co., Ltd. (currently Mitsubishi Chemical Corporation), jER (registered trademark) series); bisphenol F type epoxy compounds such as Epikote 152, Epikote 154 (Japan Epoxy Resins Co., Ltd. (currently Mitsubishi Chemical Corporation), jER (registered trademark) series), EPPN201, EPPN202 (all manufactured by Nippon Kayaku Co., Ltd.); cresol novolac epoxy compounds such as ECON-102, ECON-103S, ECON-104S, ECON-1020, ECON-1025, and ECON-1027 (all manufactured by Nippon Kayaku Co., Ltd.) and Epikote 180S75 (manufactured by Japan Epoxy Resins Co., Ltd. (currently manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) series)); naphthalene epoxy compounds such as V8000-C7 (manufactured by DIC Corporation); Denacol EX-252 (manufactured by Nagase ChemteX Corporation); alicyclic epoxy compounds such as CY175, CY1770, CY179, Araldite CY-182, Araldite CY-192, Araldite CY-184 (all manufactured by BASF), Epiclon 200, Epiclon 400 (all manufactured by DIC Corporation), Epicoat 871, Epicoat 872 (all manufactured by Japan Epoxy Resins Co., Ltd. (now Mitsubishi Chemical Corporation, jER (registered trademark) series)), ED-5661, ED-5662 (all manufactured by Celanese Coatings Co., Ltd.);Examples of such aliphatic polyglycidyl ether compounds include Denacol EX-611, Denacol EX-612, Denacol EX-614, Denacol EX-622, Denacol EX-411, Denacol EX-512, Denacol EX-522, Denacol EX-421, Denacol EX-313, Denacol EX-314, and Denacol EX-312 (all manufactured by Nagase ChemteX Corporation);

[0059] Examples of melamine derivatives, benzoguanamine derivatives, or glycolurils in which the hydrogen atom of an amino group is substituted with a methylol group, an alkoxymethyl group, or both include MX-750 in which an average of 3.7 methoxymethyl groups are substituted per triazine ring, and MW-30 in which an average of 5.8 methoxymethyl groups are substituted per triazine ring (both manufactured by Sanwa Chemical Co., Ltd.); methoxymethylated melamines such as Cymel 300, Cymel 301, Cymel 303, Cymel 350, Cymel 370, Cymel 771, Cymel 325, Cymel 327, Cymel 703, and Cymel 712; and methoxymethylated butoxymethylated melamines such as Cymel 235, Cymel 236, Cymel 238, Cymel 212, Cymel 253, and Cymel 254. methylolated glycoluril such as Cymel 1170; butoxymethylated glycoluril such as Cymel 1172 (all manufactured by Mitsui Cyanamid Co., Ltd. (now Nippon Cytec Industries Co., Ltd.)).

[0060] By applying the release layer-forming composition of the present invention described above to a substrate and heating it, a thin film (release layer) made of polyimide having high heat resistance, moderate flexibility, and a moderate linear expansion coefficient can be obtained.

[0061] Examples of the substrate (base material) include glass, plastic (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetyl cellulose, ABS, AS, norbornene-based resins, etc.), metal (silicon wafer, etc.), wood, paper, slate, etc., with glass or silicon wafer being preferred. In particular, glass is more preferred because the release layer obtained from the release layer-forming composition according to the present invention has sufficient adhesion to it. The substrate surface may be composed of a single material or two or more materials. Examples of embodiments in which the substrate surface is composed of two or more materials include an embodiment in which a certain area of ​​the substrate surface is composed of one material and the remaining surface is composed of another material, and an embodiment in which a material in a pattern such as a dot pattern or line and space pattern is present among the other materials across the entire substrate surface.

[0062] The application method is not particularly limited, and examples thereof include cast coating, spin coating, blade coating, dip coating, roll coating, bar coating, die coating, inkjet printing, and printing methods (relief printing, intaglio printing, lithography, screen printing, etc.).

[0063] In addition, methods for imidizing the polyamic acid contained in the release layer-forming composition of the present invention include thermal imidization, in which the composition applied to a substrate is heated as is, and catalytic imidization, in which a catalyst is added to the composition and then heated.

[0064] The catalytic imidization of polyamic acid is carried out by adding a catalyst to the release layer-forming composition of the present invention, stirring the mixture to prepare a catalyst-added composition, and then applying the composition to a substrate and heating the mixture to obtain a resin thin film (release layer). The amount of catalyst is 0.1 to 30 times by mole, preferably 1 to 20 times by mole, the amount of amide acid groups. Acetic anhydride or the like can also be added as a dehydrating agent to the catalyst-added composition, in an amount of 1 to 50 times by mole, preferably 3 to 30 times by mole, the amount of amide acid groups.

[0065] As the imidization catalyst, a tertiary amine is preferably used, and examples of the tertiary amine include pyridine, substituted pyridines, imidazole, substituted imidazoles, picoline, quinoline, and isoquinoline.

[0066] The heating temperature during thermal imidization and catalytic imidization is typically determined appropriately within the range of 50 to 550°C, but is preferably 200°C or higher and 450°C or lower. Setting the heating temperature in this manner allows the imidization reaction to proceed sufficiently while preventing the resulting film from becoming brittle. The heating time cannot be generally specified because it varies depending on the heating temperature, but is typically 5 minutes to 5 hours. The imidization rate may be in the range of 50 to 100%.

[0067] In a preferred example of the heating mode in the present invention, taking into consideration the heat resistance of the resulting resin thin film and the versatility of the equipment used, the applied composition is heated at 50 to 100°C for 1 minute to 30 minutes, then heated at 110 to 150°C for 3 minutes to 1 hour, and then the heating temperature is gradually increased to finally heat at 200 to 300°C for 10 minutes to 2 hours. In particular, heating at 80 to 120°C for 5 to 30 minutes, and then at 230 to 300°C for 30 minutes to 1 hour is preferred.

[0068] Examples of heating equipment include a hot plate, an oven, etc. The heating atmosphere may be air or an inert gas, and may be atmospheric pressure or reduced pressure.

[0069] The thickness of the release layer is usually about 0.01 to 10 μm, preferably about 0.05 to 5 μm, and the thickness of the coating film before heating is adjusted to achieve a resin thin film of the desired thickness.

[0070] The release layer described above has excellent adhesion to a substrate, particularly a glass substrate, and moderate adhesion and moderate release properties to a resin substrate. Therefore, the release layer according to the present invention can be suitably used in the manufacturing process of a flexible electronic device to release the resin substrate together with circuits and the like formed on the resin substrate from the substrate without damaging the resin substrate.

[0071] An example of a method for manufacturing a flexible electronic device using the release layer of the present invention is described below. A release layer is formed on a glass substrate by the aforementioned method using the release layer-forming composition of the present invention. A resin solution for forming a resin substrate is applied onto this release layer, and the coating is heated to form a resin substrate fixed to the glass substrate via the release layer of the present invention. In this process, the resin substrate is formed so as to completely cover the release layer and have an area larger than that of the release layer. Examples of the resin substrate include resin substrates made of polyimide resin, acrylic resin, and cycloolefin resin, which are typical resin substrates for flexible electronic devices. Examples of resin solutions for forming such substrates include polyimide solutions, polyamic acid solutions, acrylic polymer solutions, cycloolefin polymer solutions, and cycloolefin copolymer solutions. The resin substrate can be formed according to conventional methods.

[0072] Next, a desired circuit is formed on the resin substrate fixed to the base via the release layer according to the present invention, and then the resin substrate is cut, for example, along the release layer, and the resin substrate together with the circuit is peeled off from the release layer to separate the resin substrate from the base. At this time, a part of the base may be cut together with the release layer.

[0073] In this case, the object to be peeled may be a single layer or multiple layers. To fabricate various devices, multiple layers are more practical. The layer immediately above the peel layer among the layers of the object to be peeled (usually a resin substrate) depends on the peel layer to be used, but it is preferable to use a material that has good peelability with the peel layer, in other words, a material that does not have good adhesion with the peel layer to be used.

[0074] The present invention also provides the following method for producing an object to be peeled, comprising the steps of: applying the release layer-forming composition of the present invention onto a substrate and baking the composition to form a release layer; forming an object to be peeled on the release layer; and peeling the object to be peeled from the release layer.

[0075] In the above manufacturing method, the firing conditions for forming the release layer can be the same as those described above. The "object to be peeled" may be a single layer or multiple layers. The layer (usually a resin substrate) immediately above the release layer of the "object to be peeled" depends on the release layer used, but it is preferable that the layer has good releasability from the release layer, in other words, poor adhesion to the release layer used.

[0076] Furthermore, the present invention provides a laminate applicable to a flexible electronic device, comprising: a substrate; a release layer formed on the substrate; and a resin substrate formed on the release layer, wherein the release layer is formed from the release layer-forming composition of the present invention, and the adhesive strength between the resin substrate and the release layer is greater than the adhesive strength between the release layer and the substrate. Note that the magnitude of the adhesive strength can be confirmed, for example, by a cross-cut test shown in the examples described later.

[0077] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The abbreviations of the compounds used in the examples, and the methods for measuring the number average molecular weight and weight average molecular weight are as follows.

[0078] <Compound abbreviations> PMDA: Pyromellitic dianhydride ODPA: 4,4'-oxydiphthalic anhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride DA-1: 1,2-bis(4-aminophenoxy)ethane DA-2: 1,3-bis(4-aminophenoxy)propane DA-3: 1,4-bis(4-aminophenoxy)butane DA-4: 1,5-bis(4-aminophenoxy)pentane DA-5: 1,6-bis(4-aminophenoxy)hexane DA-6: 1,10-bis(4-aminophenoxy)decane DA-7: 4,4'-ethylenedianiline TFMB: 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl p-PDA: p-phenylenediamine m-PDA: m-phenylenediamine ODA: 4,4'-oxydianiline DA-4P: 1,3-bis(4-aminophenoxy)benzene An: aniline PA: phthalic anhydride NMP: N-methyl-2-pyrrolidone NEP: N-ethyl-2-pyrrolidone EL: ethyl lactate EDM: diethylene glycol ethyl methyl ether

[0079] <Measurement of Number Average Molecular Weight and Weight Average Molecular Weight> The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the polymer were measured using a GPC apparatus manufactured by JASCO Corporation (column: KD803 and KD805 manufactured by Shodex; eluent: dimethylformamide / LiBr.HO (30 mM) / HPO (30 mM) / THF (1%); flow rate: 1.0 mL / min; column temperature: 50°C; Mw: standard polyethylene oxide equivalent value) (the same applies to the following examples and comparative examples).

[0080] [1] Polymer Synthesis Polyamic acid was synthesized by the following method: The polymer was not isolated from the resulting polymer-containing reaction solution, and the reaction solution was diluted as described below to prepare a composition for forming a resin substrate or a composition for forming a release layer.

[0081] Synthesis Example 1 Synthesis of Polyamic Acid A1 2.06 g (8.4 mmol) of DA-1 was dissolved in 36 g of NEP. 1.94 g (8.9 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain Polyamic Acid A1. The Mw of Polyamic Acid A1 was 56,180, and the Mw / Mn was 1.9.

[0082] Synthesis Example 2 Synthesis of Polyamic Acid A2 2.16 g (8.86 mmol) of DA-1 was dissolved in 36 g of NMP. 1.84 g (8.42 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain Polyamic Acid A2. The Mw of Polyamic Acid A2 was 23,350, and the Mw / Mn was 2.0.

[0083] Synthesis Example 3 Synthesis of Polyamic Acid A3 1.93 g (7.88 mmol) of DA-1 and 0.16 g (1.75 mmol) of An were dissolved in 36 g of NMP. 1.91 g (8.76 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain Polyamic Acid A3. The Mw of Polyamic Acid A3 was 17,970, and the Mw / Mn was 1.8.

[0084] Synthesis Example 4 Synthesis of Polyamic Acid A4 1.98 g (7.67 mmol) of DA-2 and 0.16 g (1.71 mmol) of An were dissolved in 36 g of NMP. 1.86 g (8.53 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain polyamic acid A4. The Mw of polyamic acid A4 was 16,250, and the Mw / Mn was 1.8.

[0085] Synthesis Example 5 Synthesis of Polyamic Acid A5 2.04 g (7.47 mmol) of DA-3 and 0.16 g (1.66 mmol) of An were dissolved in 36 g of NMP. 1.81 g (8.30 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain Polyamic Acid A5. The Mw of Polyamic Acid A5 was 19,180, and the Mw / Mn was 1.8.

[0086] Synthesis Example 6 Synthesis of Polyamic Acid A6 2.08 g (7.32 mmol) of DA-4 and 0.15 g (1.63 mmol) of An were dissolved in 36 g of NMP. 1.77 g (8.13 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain Polyamic Acid A6. The Mw of Polyamic Acid A6 was 18,070, and the Mw / Mn was 1.8.

[0087] Synthesis Example 7 Synthesis of Polyamic Acid A7 2.13 g (7.10 mmol) of DA-5 and 0.15 g (1.58 mmol) of An were dissolved in 36 g of NMP. 1.72 g (7.89 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain Polyamic Acid A7. The Mw of Polyamic Acid A7 was 18,480, and the Mw / Mn was 1.9.

[0088] Synthesis Example 8 Synthesis of Polyamic Acid A8 2.30 g (6.46 mmol) of DA-6 and 0.13 g (1.44 mmol) of An were dissolved in 36 g of NMP. 1.57 g (7.17 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain polyamic acid A8. The Mw of polyamic acid A8 was 15,380, and the Mw / Mn was 1.8.

[0089] Synthesis Example 9 Synthesis of Polyamic Acid A9 2.08 g (8.5 mmol) of DA-1 was dissolved in 36 g of NEP. To the resulting solution, 1.67 g (7.7 mmol) of PMDA and 0.25 g (1.7 mmol) of PA were added, and the mixture was reacted for 24 hours at 23°C under a nitrogen atmosphere to obtain Polyamic Acid A9. The Mw of Polyamic Acid A9 was 17,050, and the Mw / Mn was 1.9.

[0090] Synthesis Example 10 Synthesis of Polyamic Acid A10 2.19 g (8.0 mmol) of DA-3 was dissolved in 36 g of NEP. To the resulting solution, 1.58 g (7.2 mmol) of PMDA and 0.24 g (1.6 mmol) of PA were added, and the mixture was allowed to react for 24 hours at 23°C under a nitrogen atmosphere to obtain polyamic acid A10. The Mw of polyamic acid A10 was 18,670, and the Mw / Mn was 1.7.

[0091] Synthesis Example 11 Synthesis of Polyamic Acid A11 1.76 g (6.4 mmol) of DA-3 and 0.13 g (1.4 mmol) of An were dissolved in 36 g of NEP. 2.10 g (7.2 mmol) of BPDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain polyamic acid A11. The Mw of polyamic acid A11 was 17,440, and the Mw / Mn was 1.9.

[0092] Synthesis Example 12 Synthesis of Polyamic Acid A12 1.77 g (7.2 mmol) of DA-1 was dissolved in 36 g of NEP. 2.02 g (6.5 mmol) of ODPA and 0.21 g (1.4 mmol) of PA were added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain polyamic acid A12. The Mw of polyamic acid A12 was 10,620, and the Mw / Mn was 1.7.

[0093] Synthesis Example 13 Synthesis of Polyamic Acid A13 1.22 g (4.5 mmol) of DA-3 and 0.83 g (8.9 mmol) of An were dissolved in 36 g of NEP. 1.95 g (9.9 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain polyamic acid A13. The Mw of polyamic acid A13 was 4,090, and the Mw / Mn was 1.6.

[0094] Synthesis Example 14 Synthesis of Polyamic Acid A14 1.78 g (6.5 mmol) of DA-3 and 0.37 g (1.6 mmol) of TFMB were dissolved in 36 g of NEP. To the resulting solution, 1.61 g (7.4 mmol) of PMDA and 0.24 g (1.6 mmol) of PA were added, and the mixture was reacted for 24 hours at 23°C under a nitrogen atmosphere to obtain polyamic acid A14. The Mw of polyamic acid A14 was 19,450, and the Mw / Mn was 2.0.

[0095] Synthesis Example 15 Synthesis of Polyamic Acid A15 1.94 g (9.1 mmol) of DA-7 was dissolved in 36 g of NEP. To the resulting solution, 1.79 g (8.2 mmol) of PMDA and 0.27 g (1.8 mmol) of PA were added, and the mixture was reacted for 24 hours at 23°C under a nitrogen atmosphere to obtain polyamic acid A15. The Mw of polyamic acid A15 was 12,710, and the Mw / Mn was 1.8.

[0096] Comparative Synthesis Example 1 Synthesis of Polyamic Acid C1 1.16 g (10.7 mmol) of p-PDA and 0.24 g (2.4 mmol) of An were dissolved in 36 g of NEP. 2.60 g (11.9 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain polyamic acid C1. The Mw of polyamic acid C1 was 11,000, and the Mw / Mn was 1.7.

[0097] Comparative Synthesis Example 2: Synthesis of polyamic acid C2 1.16 g (10.7 mmol) of m-PDA and 0.24 g (2.4 mmol) of An were dissolved in 36 g of NEP. 2.60 g (11.9 mmol) of PMDA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain polyamic acid C2. The Mw of polyamic acid C2 was 7,010, and the Mw / Mn was 1.6.

[0098] Synthesis Example F2 Synthesis of Polyamic Acid F2 9.6 g (32.8 mmol) of DA-4P was dissolved in 180 g of NMP. 10.40 g (33.5 mmol) of ODPA was added to the resulting solution, and the mixture was reacted at 23°C for 24 hours under a nitrogen atmosphere to obtain polyamic acid F2. The Mw of polyamic acid F2 was 43,910, and the Mw / Mn was 2.8.

[0099] [2] Preparation of Resin Substrate Forming Composition [Preparation Example 1] Preparation of Resin Substrate Forming Composition F1

[0049] 10 g of Zeonor (registered trademark) 1020R (a cycloolefin polymer manufactured by Zeon Corporation) and 3 g of Epolead (registered trademark) GT401 (manufactured by Daicel Corporation) were added to a recovery flask containing 100 g of EDM. The solution was stirred for 24 hours under a nitrogen atmosphere to dissolve the components, thereby preparing Resin Substrate Forming Composition F1.

[0100] Preparation Example 2 Preparation of composition F2 for forming a resin substrate The reaction liquid obtained in Synthesis Example F2 was used as it was as composition F2 for forming a resin substrate.

[0101] [3] Preparation of composition for forming release layer [Example 1-1] EL and NEP were added to the reaction liquid obtained in Synthesis Example 1, and the mixture was diluted to a polymer concentration of 5% by mass and an EL concentration of 20% by mass, thereby obtaining composition 1 for forming release layer.

[0102] [Examples 1-2 to 1-15] Compositions 2 to 15 for forming a release layer were obtained in the same manner as in Example 1-1, except that the reaction liquids obtained in Synthesis Examples 2 to 15 were used instead of the reaction liquid obtained in Synthesis Example 1.

[0103] [Comparative Examples 1-1 to 1-2] Compositions 16 to 17 for forming a release layer were obtained in the same manner as in Example 1-1, except that the reaction solutions obtained in Comparative Synthesis Examples 1 and 2 were used instead of the reaction solution obtained in Synthesis Example 1.

[0104] [4] Formation of Release Layer [Example 2-1] Using a spin coater, the release layer-forming composition obtained in Example 1-1 was applied onto a 100 mm × 100 mm glass substrate (the same applies below) as a glass base. The resulting coating film was then heated at 80°C for 2 minutes using a hot plate, then at 120°C for 5 minutes using a hot plate, and further heated at 230°C for 60 minutes using a hot plate to form a release layer with a thickness of 100 to 200 nm on the glass substrate, thereby obtaining a glass substrate with a release layer.

[0105] [Examples 2-2 to 2-15] A release layer was formed in the same manner as in Example 2-1, except that the release layer-forming compositions obtained in Examples 1-2 to 1-15 were used instead of the release layer-forming composition obtained in Example 1-1, to obtain a glass substrate with a release layer.

[0106] [Comparative Examples 2-1 to 2-2] A release layer was formed in the same manner as in Example 2-1, except that the release layer-forming compositions obtained in Comparative Examples 1-1 and 1-2 were used instead of the release layer-forming composition obtained in Example 1-1, and a glass substrate with a release layer was obtained.

[0107] [5] Formation of Resin Substrate and Evaluation of Peelability [Example 3-1] Using a spin coater, a resin substrate-forming composition was applied onto the release layer (resin thin film) on the glass substrate with a release layer obtained in Example 2-1. The resulting coating was then heated using a hot plate to form a resin substrate layer. The baking conditions for each resin substrate-forming composition are described below. Resin substrate-forming composition F1: Heated using a hot plate at 80°C for 2 minutes, then heated using a hot plate at 230°C for 30 minutes, to form a resin substrate F1 with a thickness of approximately 3 μm on the release layer. Resin substrate-forming composition F2: Heated using a hot plate at 80°C for 2 minutes, then heated using a hot plate at 120°C for 5 minutes, and then heated using a hot plate at 230°C for 60 minutes, to form a resin substrate F2 with a thickness of approximately 10 μm on the release layer.

[0108] [Examples 3-2 to 3-15, Comparative Examples 3-1 to 3-2] Polyimide substrates were formed on a release layer in the same manner as in Example 3-1, except that the glass substrates with release layers obtained in Examples 2-2 to 2-15 and Comparative Examples 2-1 and 2-2 were used instead of the glass substrate with release layer obtained in Example 2-1.

[0109] <Evaluation of Peel Strength of Resin Substrate> 25 mm x 70 mm strips were prepared from the resin substrates and glass substrates with release layers obtained in Examples 3-1 to 3-15 and Comparative Examples 3-1 to 3-2. Furthermore, Cellotape (registered trademark) (CT-24, manufactured by Nichiban Co., Ltd.) was attached, and then the tape was peeled off at a peel angle of 90° and a peel speed of 300 mm / min using an Autograph AGS-X500N (manufactured by Shimadzu Corporation) to measure the peel strength. Those that could not be peeled were deemed unpeelable. The results are shown in Table 1.

[0110] aa: Peel force of less than 0.20 N / 25 mm a: Peel force of 0.20 N / 25 mm or more and less than 0.40 N / 25 mm b: Peel force of 0.40 N / 25 mm or more and less than 0.60 N / 25 mm 1b: Peel force of 0.60 N / 25 mm or more and less than 0.80 N / 25 mm 2b: Peel force of 0.80 N / 25 mm or more and less than 1.00 N / 25 mm 3b: Peel force of 1.00 N / 25 mm or more 4b: No peeling

[0111] [6] Curability Evaluation The glass substrates with release layers obtained in Examples 2-1 to 2-15 and Comparative Examples 2-1 to 2-2 were immersed in NMP at room temperature for 5 minutes. After that, they were washed with pure water and then heated at 100°C for 2 minutes using a hot plate to dry. The film thickness was measured before and after immersion in NMP, and the residual film ratio was calculated using the following formula. The degree of curing was evaluated based on the following criteria. The results are shown in Table 1. <Formula for calculating residual film ratio> {(film thickness after immersion) / (film thickness before immersion)} x 100 <Evaluation criteria> ◎: residual film ratio ≧95% ○: residual film ratio 70-94% △: residual film ratio 50-69% ×: residual film ratio <50%

[0112]

[0113] From the results in Table 1, it was confirmed that the release layers of the Examples had excellent adhesion to the curable substrate at low temperatures and were easily peeled from the resin substrate. On the other hand, it was confirmed that the release layers of the Comparative Examples had excellent adhesion to the substrate, but were insufficiently cured at low temperatures and were difficult to peel from the resin substrate.

Claims

1. The composition includes a polyamic acid obtained by reacting an aromatic diamine having a linear alkylene group having 2 to 6 carbon atoms in the main chain with an aromatic tetracarboxylic dianhydride, and an organic solvent, The release layer-forming composition, wherein the polyamic acid has at least a structural unit represented by the following formula (1): 【Chemical 1】 [(In the formula, Ar 1 represents a divalent organic group represented by the following formula (2), and Ar 2 represents a tetravalent organic group having an aromatic group.) 【Chemistry 2】 (In the formula, X represents a linear alkylene group having 2 to 6 carbon atoms; Y 1 and Y 2 may be the same or different and represent a single bond or an ether bond; R 1 and R 2 each independently represent a halogen atom or an alkyl group having 1 to 4 carbon atoms.) n1 and n2 each independently represent an integer of 0 to 4. * represents a bond.)

2. 2. The composition for forming a release layer according to claim 1, wherein the content of the aromatic diamine having a linear alkylene group having 2 to 6 carbon atoms in the main chain portion is 50 to 100 mol % of the total diamine components.

3. 2. The composition for forming a release layer according to claim 1, wherein the polyamic acid is a polyamic acid represented by the following formula (3) in which both ends are capped with an aromatic monoamine, or a polyamic acid represented by the following formula (4) in which both ends are capped with an aromatic dicarboxylic acid. 【Chemistry 3】 【Chemistry 4】 (In the formula, Ar 1 and Ar 2 has the same definition as in formula (1). 3 and Ar 4 are each independently an aromatic group having 6 to 30 carbon atoms, which may have a halogen atom, an alkyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

4. The above Ar 3 or Ar 4 The composition for forming a release layer according to claim 3 , wherein is an optionally substituted benzene ring or naphthalene ring.

5. A release layer obtained from the composition for forming a release layer according to claim 1 .

6. A method for producing a release layer, comprising the step of firing the composition for forming a release layer according to any one of claims 1 to 4 at a maximum temperature of less than 400°C.

7. 6. A laminate comprising a base, the release layer according to claim 5, and a resin substrate laminated in that order, wherein the release layer has greater adhesion to the base than to the resin substrate.

8. A method for producing a flexible electronic device having a resin substrate, comprising using the release layer according to claim 5.

9. A method for producing a flexible electronic device, comprising the steps of applying the composition for forming a resin substrate onto the release layer according to claim 5 and then baking the composition at a maximum temperature of less than 400°C to form a resin substrate.

10. 10. The manufacturing method according to claim 8, wherein the resin substrate is a substrate made of a free-standing film.

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