JP2017203058A - Imide crosslinked resin, transparent film, and surface protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imide crosslinked resin which has good heat resistance and can be suitably used as a resin material for a surface protective film.SOLUTION: The imide crosslinked resin is obtained by crosslinking a copolymer having a cyclic olefin unit and an unsaturated dicarboxylic acid anhydride unit with a diamine. There are also provided a transparent film containing the resin and a surface protective film including the transparent film and a metal deposition layer provided on at least one surface of the film. Preferably, the cyclic olefin unit has a norbornene skeleton, and the unsaturated dicarboxylic acid anhydride unit is maleic anhydride.SELECTED DRAWING: None

Description

  The present invention relates to an imide cross-linked resin, a transparent film, and a surface protective film.

  In recent years, with the widespread use of portable information terminals and the like, the demand for surface protective films for protecting the display surface is increasing. For example, Patent Document 1 discloses an organic electroluminescence display device in which a cover window is disposed on a polarizing plate or a touch panel.

JP 2010-232162 A

  The surface protective film is produced, for example, by vapor-depositing a metal such as aluminum on one surface of the film substrate. At this time, the film substrate is required to have sufficient heat resistance.

  An object of this invention is to provide the imide bridge | crosslinking type resin which has favorable heat resistance and can be utilized suitably as a resin material for surface protection films. Another object of the present invention is to provide a transparent film that contains an imide-crosslinked resin and can be suitably used as a film substrate for a surface protective film. Furthermore, an object of this invention is to provide the surface protection film provided with the said transparent film.

  One aspect of the present invention relates to an imide crosslinked resin obtained by crosslinking a copolymer having a cyclic olefin unit and an unsaturated dicarboxylic anhydride unit with a diamine.

  In one embodiment, the cyclic olefin unit may have a norbornane skeleton.

  In one embodiment, the unsaturated dicarboxylic anhydride unit may comprise a maleic anhydride unit.

  Another aspect of the present invention relates to a transparent film containing an imide crosslinked resin.

  Still another aspect of the present invention relates to a surface protective film comprising a transparent film and a metal vapor deposition layer provided on at least one surface of the transparent film.

  ADVANTAGE OF THE INVENTION According to this invention, the imide bridge | crosslinking type resin which has favorable heat resistance and can be utilized suitably as a resin material for surface protection films is provided. Moreover, according to this invention, the surface protection film provided with the said imide bridge | crosslinking type resin and suitable as a film base material for surface protection films, and the said transparent film is provided.

  Hereinafter, preferred embodiments of the present invention will be described.

(Imide crosslinking resin)
The imide cross-linking resin according to this embodiment is a cross-linked product obtained by cross-linking a copolymer having a cyclic olefin unit and an unsaturated dicarboxylic anhydride unit with a diamine.

  In this specification, the cyclic olefin unit is a structural unit derived from a cyclic olefin, and the unsaturated dicarboxylic acid anhydride unit is a structural unit derived from an unsaturated dicarboxylic acid anhydride. That is, the copolymer can be referred to as a copolymer having a structural unit derived from a cyclic olefin and a structural unit derived from an unsaturated dicarboxylic acid anhydride, and is a monomer component containing a cyclic olefin and an unsaturated dicarboxylic acid anhydride. It can also be called a copolymer.

  The imide crosslinked resin according to this embodiment has an imide bond formed by a reaction between an acid anhydride in the copolymer and an amino group in the diamine. The imide cross-linking resin according to the present embodiment has sufficient light transmittance and good heat resistance by including a cyclic structure derived from a cyclic olefin and a cross-linked structure via an imide bond in the molecule. For this reason, the imide bridge | crosslinking type resin which concerns on this embodiment can be utilized suitably as a resin material for surface protection films.

<Copolymer>
The copolymer in the present embodiment is a polymer having a cyclic olefin unit and an unsaturated dicarboxylic anhydride unit and capable of being crosslinked by a diamine.

In the copolymer, the total amount of unsaturated dicarboxylic acid anhydride unit content C ₂ (mol) and maleimide unit content C ₃ (mol) described later relative to cyclic olefin unit content C ₁ (mol). The ratio of C ₂ + C ₃ (mol) (C ₂ + C ₃ ) / C ₁ may be, for example, 0.5 to 2.0, and preferably 0.95 to 1.05.

The ratio C ₂ / (C ₂ + C ₃ ) of the content C ₂ of unsaturated dicarboxylic anhydride units to the total amount C ₂ + C ₃ may be, for example, 0.01 or more, preferably 0.5 or more. 1 (that is, the content of maleimide units is 0).

  The number average molecular weight Mn of the copolymer may be, for example, 190 or more, preferably 1000 or more, and may be 3000 or more. By increasing the number average molecular weight Mn of the copolymer, the heat resistance of the imide crosslinked resin tends to be further improved. The number average molecular weight Mn of the copolymer may be, for example, 500,000 or less, preferably 10,000 or less, and may be 7,000 or less. By reducing the number average molecular weight Mn of the copolymer, the reaction rate of the crosslinking reaction with diamine tends to be improved.

  In the copolymer, the molecular weight distribution Mw / Mn, which is the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, may be, for example, 10 or less, and preferably 5 or less. When Mw / Mn is small, the heat resistance of the imide cross-linked resin is further improved, and the amount of volatile components in the imide cross-linked resin tends to be reduced.

In addition, in this specification, the number average molecular weight Mn and the weight average molecular weight Mw of a copolymer show the value measured on condition of the following by GPC measuring method.
Equipment: “RID-10A / CBM-20A / DGU-20A3, manufactured by Shimadzu Corporation
LC-20AD / DPD-M20A / CTO-20A "
Column: “TSKgel superHM-N” manufactured by Tosoh Corporation
Detector: Differential refractive index detector (RI detector / built-in)
Solvent: Chloroform Temperature: 40 ° C
Flow rate: 0.3 mL / min Injection volume: 20 μL
Concentration: 0.1% by weight
Calibration sample: Monodisperse polystyrene Calibration method: Polystyrene

(I) Cyclic olefin unit The cyclic olefin unit is a structural unit derived from a cyclic olefin. The cyclic olefin is a compound having a ring structure and a carbon-carbon double bond including a carbon atom constituting the ring structure, and capable of being polymerized with an unsaturated dicarboxylic acid anhydride.

  The cyclic olefin may be, for example, a compound containing a ring structure having at least one carbon-carbon double bond in the ring. Such a cyclic olefin easily undergoes a polymerization reaction with an unsaturated dicarboxylic acid anhydride. Further, according to such a cyclic olefin, since a ring structure is incorporated in the main chain of the copolymer, the shape and mobility of the main chain are limited, and the imide cross-linked resin is further excellent in heat resistance and optical characteristics. Tends to be obtained.

  The ring structure of the cyclic olefin may be a monocyclic system or a polycyclic system. Examples of the monocyclic ring structure include a cycloalkene skeleton, a cycloalkadiene skeleton, a cycloalkatriene skeleton, and the like. Examples of these ring structures include ring structures represented by the following formulas (1-1) to (1-5).

Examples of the polycyclic ring structure include a condensed ring and a bridged ring. Examples of the polycyclic ring structure include a norbornene skeleton, a norbornadiene skeleton, a bicyclo [2.2.2] oct-2-ene skeleton, a bicyclo [2.2.2] octa-2,5-diene skeleton, Cyclopentadiene skeleton, dihydrodicyclopentadiene skeleton, acenaphthylene skeleton, indene skeleton, tetrahydroindene skeleton, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodec-4-ene skeleton, and the like. Examples of these ring structures include ring structures represented by the following formulas (2-1) to (2-11).

  The ring structure of the cyclic olefin may have a substituent. In addition, the ring structure may be condensed with another ring, and may form a spiro ring with another ring.

  Examples of the cyclic olefin include compounds having structures represented by the following formulas (3-1) to (3-34).

  These cyclic olefins may have a substituent. The substituent is not particularly limited as long as it does not inhibit the polymerization reaction. The substituent may be, for example, a halogen atom, an alkyl group, a halogenated alkyl group, an alkoxy group, an aryl group, an aralkyl group, a silyl group, a carboxyl group, a hydroxy group, an amino group, or an alkoxycarbonyl group. Further, these substituents may be further substituted with other substituents.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom, a chlorine atom, or a bromine atom is preferable, and a fluorine atom is more preferable.

  The alkyl group may be linear, branched or cyclic. Carbon number of an alkyl group may be 1-30, for example, Preferably it is 1-10. Specific examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, and tert-butyl.

  The halogenated alkyl group is a group in which part or all of the hydrogen atoms of the alkyl group are substituted with halogen atoms. Examples of the alkyl group and the halogen atom are the same as described above. Examples of the halogenated alkyl group include a trifluoromethyl group, a chloromethyl group, and a bromomethyl group.

  The alkoxy group is a group represented by —OR (R represents an alkyl group), and examples of the alkyl group of R include the same examples as described above. Examples of the alkoxy group include a methoxy group, an ethoxy group, an isopropoxy group, an n-propoxy group, and a tert-butoxy group.

  The aryl group is a group having a structure in which one hydrogen atom is removed from an aromatic hydrocarbon. Examples of the aryl group include a phenyl group, a naphthyl group, and an anthracenyl group.

  An aralkyl group is a group in which part or all (preferably one) of hydrogen atoms of an alkyl group is substituted with an aryl group. Examples of the alkyl group and aryl group are the same as those described above. Examples of the aralkyl group include a benzyl group, a phenylethyl group, and a phenylpropyl group.

The silyl group is a group represented by —Si (R ′) ₃ (R ′ represents an alkyl group, an aryl group, or an aralkyl group). Examples of the alkyl group, aryl group, and aralkyl group of R ′ are as described above. The same example is given. Examples of the silyl group include a trimethylsilyl group, a dimethylphenylsilyl group, a triethylsilyl group, and a diethylphenylsilyl group.

  The alkoxycarbonyl group is a group represented by —COOR (R represents an alkyl group), and examples of the alkyl group of R include the same examples as described above. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, an isopropoxycarbonyl group, a tert-butoxycarbonyl group, and the like.

  The cyclic olefin is preferably a compound containing no hetero atom other than oxygen, nitrogen and sulfur, and more preferably a hydrocarbon containing no hetero atom.

  Specific examples of the cyclic olefin include, for example, acenaphthylene, 5-acetyl-2-norbornenebicyclo [3.2.1] oct-2-ene, and [bicyclo [2.2.1] hept-5-en-2- Yl] triethoxysilane, tert-butyl-5-norbornene-2-carboxylate, dicyclopentadiene, 5,6-dihydrodicyclopentadiene, 5-ethylidene-2-norbornene, hydroxydicyclopentadiene, 2-norbornene, 5 -Norbornene-2,3-dicarboxylic anhydride, 2,5-norbornadiene, 5-norbornene-2,2-dimethanol, methyl 5-norbornene-2-carboxylate 5-norbornene-2-carboxylate, 5-norbornene -2,3-dimethanol, cis-5-norbornene-exo- , 3-dicarboxylic anhydride, 5-norbornene-2-endo, 3-endo-dimethanol, 5-norbornene-2-exo, 3-exo-dimethanol, 5-norbornen-2-yl acetate, 5-norbornene -2-carbonitrile, 5-norbornene-2,3-dicarboximide, 5-norbornene-2-methylamine, 5-norbornene-2-methanol, N- (2-ethylhexyl) -5-norbornene-2,3 -Dicarboximide, 3a, 4,7,7a-tetrahydroindene, tetracyclo [6.2.1.13,6.02,7] dode-4-ene, 4-vinyl-1-cyclohexene, 5-vinyl Bicyclo [2.2.1] hept-2-ene, tricyclopentadiene, dimethanobenzindene, dimethanofluorene, α Pinene, beta-pinene, limonene, and the like.

  When the cyclic olefin has two or more carbon-carbon double bonds, some or all of the carbon-carbon double bonds may react in the polymerization reaction. That is, the cyclic olefin unit may be a structural unit obtained by reacting part or all of the carbon-carbon double bond of the cyclic olefin by a polymerization reaction, and part of the carbon-carbon double bond of the cyclic olefin. Alternatively, it may be a structural unit having a structure in which all are replaced by single bonds.

  In the cyclic olefin unit, at least a part of the ring structure preferably constitutes the main chain of the copolymer. Thereby, the shape and mobility of the main chain of the copolymer are controlled by the cyclic structure of the cyclic olefin unit, and an imide-crosslinked resin having further excellent heat resistance and optical properties can be obtained.

(Ii) Unsaturated dicarboxylic acid anhydride unit An unsaturated dicarboxylic acid anhydride unit is a structural unit derived from an unsaturated dicarboxylic acid anhydride. An unsaturated dicarboxylic acid anhydride is a compound formed by an unsaturated dicarboxylic acid having a carbon-carbon double bond and two carboxyl groups forming an acid anhydride by intramolecular dehydration.

  Examples of the unsaturated dicarboxylic acid anhydride include maleic anhydride, citraconic anhydride, itaconic anhydride, 2,3-dimethylmaleic anhydride, 2- (2-carboxyethyl) -3-methylmaleic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, phenylmaleic anhydride, 2,3-diphenylmaleic anhydride, allyl succinic anhydride, (2-methyl-2-propenyl) succinic anhydride, 2-buten-1-yl succinic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, bicyclo [2.2.2] oct- 5-ene-2,3-dicarboxylic acid anhydride and the like.

  The unsaturated dicarboxylic acid anhydride may be, for example, a compound having a structure represented by the following formula (4-1).

In the formula, R ¹ represents a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group or an aryl group, and the two R ^{1 s} may be the same as or different from each other.

  When the unsaturated dicarboxylic acid anhydride is a compound having a structure represented by the formula (4-1), the shape and mobility of the main chain of the copolymer are controlled by the ring structure derived from the unsaturated dicarboxylic acid anhydride. Therefore, an imide cross-linked resin having further excellent heat resistance and optical properties can be obtained.

Examples of the halogen atom for R ¹ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The halogen atom is preferably a fluorine atom, a chlorine atom or a bromine atom, and more preferably a fluorine atom.

The alkyl group for R ¹ may be linear, branched or cyclic. Carbon number of an alkyl group may be 1-30, for example, Preferably it is 1-10. Specific examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, and tert-butyl.

The halogenated alkyl group for R ¹ is a group in which part or all of the hydrogen atoms of the alkyl group are substituted with halogen atoms. Examples of the alkyl group and the halogen atom are the same as described above. Examples of the halogenated alkyl group include a trifluoromethyl group, a chloromethyl group, and a bromomethyl group.

Examples of the aryl group for R ¹ include a phenyl group, a naphthyl group, and an anthracenyl group.

R ¹ is preferably a hydrogen atom, an alkyl group or a halogenated alkyl group, more preferably a hydrogen atom or an alkyl group. Further, from the viewpoint of excellent reactivity with the cyclic olefin and facilitating the production of the copolymer, at least one of R ¹ is preferably a hydrogen atom.

  The unsaturated dicarboxylic acid anhydride unit may have, for example, a structure in which some or all of the hydrogen atoms of succinic anhydride are removed.

When the unsaturated dicarboxylic acid anhydride is a compound having a structure represented by the formula (4-1), the unsaturated dicarboxylic acid anhydride unit is a structural unit having a structure represented by the following formula (4-2) It may be. In the formula, R ¹ has the same meaning as described above.

(Iii) Maleimide-based unit The copolymer in the present embodiment may further have a structural unit (maleimide-based unit) derived from a maleimide-based compound. A maleimide-type compound is a compound which has a structure represented, for example by following formula (5-1), and a maleimide-type unit is a structural unit which has a structure represented, for example by following formula (5-2).

In the formula, R ² represents a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group or an aryl group, and two R ^{2 s} may be the same or different from each other. R ³ represents a monovalent group.

Examples of the halogen atom for R ² include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. The halogen atom is preferably a fluorine atom, a chlorine atom or a bromine atom, and more preferably a fluorine atom.

The alkyl group for R ² may be linear, branched or cyclic. Carbon number of an alkyl group may be 1-30, for example, Preferably it is 1-10. Specific examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, and tert-butyl.

The halogenated alkyl group for R ² is a group in which part or all of the hydrogen atoms of the alkyl group are substituted with halogen atoms. Examples of the alkyl group and the halogen atom are the same as described above. Examples of the halogenated alkyl group include a trifluoromethyl group, a chloromethyl group, and a bromomethyl group.

Examples of the aryl group for R ² include a phenyl group, a naphthyl group, and an anthracenyl group.

R ² is preferably a hydrogen atom, an alkyl group or a halogenated alkyl group, more preferably a hydrogen atom or an alkyl group. In addition, from the viewpoint of excellent reactivity with cyclic olefins and unsaturated dicarboxylic acid anhydrides, and easy production of the copolymer, at least one of R ² is preferably a hydrogen atom.

The monovalent group of R ³ is not particularly limited as long as it does not inhibit the polymerization reaction with the cyclic olefin. Examples of the monovalent group of R ³ include an alkyl group, a halogenated alkyl group, an aryl group, an alkoxycarbonyl group, an aralkyl group, and a silyl group. The monovalent group may further have a substituent. Examples of the substituent include a halogen atom, an alkyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, and a silyl group. Etc.

  Examples of the alkyl group, halogenated alkyl group, aryl group, aralkyl group, alkoxy group, alkoxycarbonyl group, and silyl group are the same as described above.

  The alkylthio group is a group represented by —SR (R represents an alkyl group), and examples of the alkyl group of R include the same examples as described above. Examples of the alkylthio group include a methylthio group, an ethylthio group, and a propylthio group.

  The aryloxy group and the arylthio group are groups represented by —OR ″ and —SR ″ (R ″ represents an aryl group), respectively. Can be mentioned. Examples of the aryloxy group include a phenoxy group and a naphthoxy group, and examples of the arylthio group include a phenylthio group and a naphthylthio group.

(Iv) Other structural unit The copolymer in this embodiment may further have structural units other than the above. For example, the copolymer may further have a structural unit derived from a bismaleimide compound having two maleimide groups.

  Examples of bismaleimide compounds include 4,4′-bismaleimide diphenylmethane, 1,6-bis (maleimido) hexane, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane, and 1,4-bis. (Maleimido) butane, 2,2-bis [4- (4-maleimidophenoxy) phenyl] propane, 1,2-bis (maleimido) ethane, N, N′-1,4-phenylenedimaleimide, N, N ′ Examples include -1,3-phenylene dimaleimide.

  Moreover, the copolymer may further have a structural unit derived from an olefin compound capable of alternating copolymerization with an unsaturated dicarboxylic anhydride or a maleimide compound.

  Examples of the olefin compound include styrene derivatives such as styrene, indene, α-methylstyrene, p-methylstyrene; ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl. Examples thereof include alkyl monovinyl ether derivatives such as vinyl ether.

  The copolymer in the present embodiment can be obtained, for example, by a polymerization reaction of monomer components including a cyclic olefin and an unsaturated dicarboxylic acid anhydride. The monomer component may further contain a maleimide compound and may further contain other monomers.

  The form of the polymerization reaction is not particularly limited, and may be radical polymerization, for example.

When the polymerization reaction is radical polymerization, a known radical polymerization initiator may be used as the polymerization initiator. Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide (BPO), methyl ethyl ketone peroxide, redox initiator (hydrogen peroxide and Iron (II) salt, persulfate and sodium bisulfite), triethylborane (Et ₃ B), diethyl zinc (Et ₂ Zn) and the like.

  The usage-amount of a radical polymerization initiator may be 0.1-10 mol% on the basis of the total amount of a monomer component, for example, Preferably it is 1-5 mol%.

  The polymerization reaction is preferably carried out in a solvent. Examples of the solvent include tetrahydrofuran (THF), dioxane, dioxolane, acetone, chloroform, toluene, dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), and γ-butyrolactone. , Cyclopentanone, cyclohexanone, tetramethyl urea, 1,3-dimethyl-2-imidazolidinone, glyme solvents such as diglyme, cellosolv solvents such as ethyl cellosolve, glycol ester solvents such as propylene glycol monomethyl ether acetate, Glycol ether solvents such as propylene glycol monomethyl ether can be suitably used.

  The conditions for the polymerization reaction are not particularly limited. For example, the reaction temperature may be -20 to 200 ° C, and the reaction time may be 0.1 to 100 hours.

<Crosslinked product>
The imide cross-linked resin according to this embodiment is a cross-linked product obtained by cross-linking the above copolymer with a diamine, and has an imide bond formed by a reaction between an acid anhydride in the copolymer and a diamine.

  In this embodiment, some or all of the unsaturated dicarboxylic anhydride units in the copolymer may react with diamine to form an imide bond. Based on the total amount of unsaturated dicarboxylic acid anhydride units in the copolymer, the amount of unsaturated dicarboxylic acid anhydride units remaining in the imide cross-linked resin is preferably 90 mol% or less, and 70 mol% or less. More preferably, it is more preferably 50 mol% or less.

  The diamine should just be a compound which has two amino groups which can react with the acid anhydride in a copolymer and can form an imide bond.

Examples of diamines include aromatic diamines and aliphatic diamines. In the present specification, an aromatic diamine indicates a compound having two amino groups bonded to an aromatic ring, and an aliphatic diamine indicates a compound having two amino groups bonded to an sp ³ carbon. The diamine may also be a compound having an amino group bonded to an aromatic ring and an amino group bonded to an sp ³ carbon.

  Examples of the aromatic diamine include compounds having structures represented by the following formulas (6-1) to (6-4).

In the formula, Q ¹ represents a divalent group.

  These aromatic diamines may have a substituent. The substituent is not particularly limited as long as it does not inhibit the crosslinking reaction. Substituents are, for example, halogen atoms, alkyl groups, halogenated alkyl groups, aryl groups, sulfo groups, alkoxy groups, aryloxy groups, silyl groups, hydroxy groups, thiol groups, alkylthio groups, arylthio groups, nitrile groups, ketone groups. May be a carboxyl group or the like. Further, these substituents may be further substituted with other substituents.

  Examples of the halogen atom, alkyl group, halogenated alkyl group, aryl group, alkoxy group, aryloxy group, silyl group, alkylthio group, and arylthio group are the same as described above.

  The ketone group is a group represented by —COR ′ (R ′ represents an alkyl group, an aryl group or an aralkyl group). Examples of the alkyl group, aryl group and aralkyl group of R ′ are the same as those described above. It is done. Examples of the ketone group include a methylcarbonyl group, a phenylcarbonyl group, and a benzylcarbonyl group.

The divalent group in Q ¹ is not particularly limited as long as it does not inhibit the crosslinking reaction. Specific examples of the divalent group include —O—, —S—, —CH ₂ —, —SO ₂ —, —CO—, —O—C ₆ H ₄ —O—, —NHCO—, —O—. _{C 6 H 4 -C (Me)} 2 -C 6 H 4 -O -, - O-C 6 H 4 -C (CF 3) 2 -C 6 H 4 -O -, - C (Me) 2 -C _{6 H 4 -C (Me) 2} -, - O-C 6 H 4 -C 6 H 4 -O -, - O-C 6 H 4 -SO 2 -C 6 H 4 -O -, - C 6 H _{4 -, - NHCO-C 6} H 4 -CONH -, - CONH-C 6 H 4 -NHCO -, - (Si (OMe) 2 -O) n -, - (Si (OEt) 2 -O) n - , — (Si (OPh) ₂ —O) _x — and the like. In addition, x shows an integer greater than or equal to 1, Preferably it is an integer of 1-100.

  Examples of the aliphatic diamine include compounds having structures represented by the following formulas (7-1) to (7-7).

In the formula, Q ² represents a divalent group.

  These aliphatic diamines may have a substituent. The substituent is not particularly limited as long as it does not inhibit the crosslinking reaction. Substituents are, for example, halogen atoms, alkyl groups, halogenated alkyl groups, aryl groups, sulfo groups, alkoxy groups, aryloxy groups, silyl groups, hydroxy groups, thiol groups, alkylthio groups, arylthio groups, nitrile groups, ketone groups. May be a carboxyl group or the like. Further, these substituents may be further substituted with other substituents. Examples of these groups include the same examples as described above.

The divalent group in Q ² is not particularly limited as long as it does not inhibit the crosslinking reaction. Specific examples of the divalent group include —O—, —S—, —CH ₂ —, —SO ₂ —, —CO—, —O—C ₆ H ₄ —O—, —NHCO—, —O—. _{C 6 H 4 -C (Me)} 2 -C 6 H 4 -O -, - O-C 6 H 4 -C (CF 3) 2 -C 6 H 4 -O -, - C (Me) 2 -C _{6 H 4 -C (Me) 2} -, - O-C 6 H 4 -C 6 H 4 -O -, - O-C 6 H 4 -SO 2 -C 6 H 4 -O -, - C 6 H _{4 -, - NHCO-C 6} H 4 -CONH -, - CONH-C 6 H 4 -NHCO -, - (Si (OMe) 2 -O) n -, - (Si (OEt) 2 -O) n - , — (Si (OPh) ₂ —O) _x — and the like. In addition, x shows an integer greater than or equal to 1, Preferably it is an integer of 1-100.

  The diamine may be, for example, a polysiloxane diamine having an amino group introduced at the terminal or side chain of the polysiloxane. The molecular weight of the polysiloxane diamine may be, for example, 100 to 100,000, or 200 to 50,000.

Specific examples of the diamine include 1,4-phenylenediamine, 1,3-phenylenediamine, 1,2-phenylenediamine, 4,4′-ethylenedianiline, 2,2′-ethylenedianiline, 3,3 ′. -Diaminodiphenylethane, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,2'-diaminobiphenyl, 3,4'-diaminobiphenyl, 4,4'-diamino-2,2'-dimethyl Biphenyl, 4,4′-diamino-3,3′-dimethylbiphenyl, 4,4′-diaminooctafluorobiphenyl, 2,5-dimethyl-1,4-phenylenediamine, 2,3,5,6-tetrafluoro -1,4-phenylenediamine, 2,3,5,6-tetramethyl-1,4-phenylenediamine, 2,4,5,6-tetrafluoro-1,3-phenyle Diamine, 1,3,5-tris (4-aminophenyl) benzene, 2,5-dichloro-1,4-phenylenediamine, 2,6-dibromo-1,4-phenylenediamine, 2,7-diaminofluorene, 1,5-diaminonaphthalene, 1,4-diaminonaphthalene, 2,6-diaminonaphthalene, 1,3-diaminopyrene, 1,6-diaminopyrene, 1,8-diaminopyrene, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 4,4′-diamino-3,3′-dimethyldiphenylmethane, 4,4′-methylenebis (2-chloroaniline), 4,4′-methylenebis (2-ethyl-6-methylaniline), 4,4′-methylenebis (2,6-diethylaniline), 4,4 ″ -diamino- -Terphenyl, α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene, 1,1-bis (4-aminophenyl) cyclohexane, 1,3-bis [2- (4-aminophenyl) ) -2-propyl] benzene, 4,4'-diamino-2,2'-dimethylbibenzyl, o-tolidine, m-tolidine, 3,3'-diethylbenzidine, 3,3 ', 5,5'- Tetramethylbenzidine, 2,2 ′, 5,5′-tetrachlorobenzidine, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 3,3′-dihydroxybenzidine, 1,5- Bis (4-aminophenoxy) pentane, 3,3′-diaminobenzidine, o-dianisidine, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-chloropheny) ) Fluorene, 9,9-bis (4-amino-3-fluorophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene, 9,9-bis (3-amino-4-hydroxy) Phenyl) fluorene, 2,7-diamino-9,9-di-n-octylfluorene, 2,2-bis (3-amino-4-hydroxyphenyl) propane, 4,6-diaminoresorcinol, 2,5-diamino -1,4-benzenedithiol, 4,4′-diaminobenzophenone, 3,3′-diaminobenzophenone, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 1, 4-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4 ′-[1,3-phenylenebis (1-methyl-ethylidene)] bisaniline, 4, 4 ′-[1,4-phenylenebis (1-methyl-ethylidene)] bisaniline, 4,4′-bis (4-aminophenoxy) biphenyl, 1,4-bis (4-amino-2-trifluoromethylphenoxy) ) Benzene, 4,4′-diaminodiphenylamine, 4,4′-diaminobenzanilide, 3,4′-diaminobenzanilide, bis (2-aminophenyl) sulfide, bis (4-aminophenyl) sulfide, 4,4 '-Dithiodianiline, 2,2'-dithiodianiline, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 2,2′-benzidine disulfonic acid, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis (3-amino-4-hydroxyphenyl) sulfone, 3,7-diamino-2,8-dimethyldibenzothiophene sulfone, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] Hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2-bis (3-amino-4-hydroxyphenyl) hexa Fluoropropane, 2,2′-bis (trifluoromethyl) benzidine, 4,4′-diaminostilbene, , 6-diaminocarbazole, 2,6-diaminoanthraquinone, 3,9-bis [2- (3,5-diamino-2,4,6-triazaphenyl) ethyl] -2,4,8,10-tetra Oxaspiro [5.5] undecane, benzoguanamine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2, 4-diamino-6- [2- (2-methyl-1-imidazole) ethyl] -1,3,5-triazine, 2,4-diamino-6- [2- (2-undecyl-1-imidazole) ethyl ] -1,3,5-triazine, 2,2′-diamino-4,4′-bithiazole, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5 − Diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 2-methyl-1 , 3-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1,2-diamino-2-methylpropane, 2,3-dimethyl-2,3-butanediamine, 2-methyl-1,5 -Diaminopentane, 2,2'-oxybis (ethylamine), 1,2-bis (2-aminoethoxy) ethane, 1,4-butanediol bis (3-aminopropyl) ether, diethylene glycol bis (3-aminopropyl) Ether, 1,14-diamino-3,6,9,12-tetraoxatetradecane, diethylenetriamine, triethyl Rentetraamine, 3,3′-diaminodipropylamine, 2,2′-diamino-N-methyldiethylamine, 3,3′-diamino-N-methyldipropylamine, N, N′-bis (2-amino) Ethyl) -1,3-propanediamine, N, N′-bis (3-aminopropyl) ethylenediamine, N, N′-bis (3-aminopropyl) -1,4-butanediamine, 2,2′-thiobis (Ethylamine), m-xylylenediamine, p-xylylenediamine, cis-1,3-bis (aminomethyl) cyclohexane, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, amino-modified by Shin-Etsu Chemical Silicone oils (for example, X-22-1660B-3 (Mw: 4400), X-22-161B (Mw: 3000), X-22-161A (Mw: 1600) X-22-9409 (Mw: 1340), etc.), dimethylsiloxane type diamine manufactured by Gelest (for example, DMS-A11, DMS-A12, DMS-A15, DMS-A21, DMS-A31, DMS-A32, DMS). -A35, etc.), 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, cis-1,3-cyclohexanediamine, trans-1,3-cyclohexanediamine, cis-1,4-cyclohexanediamine, trans-1, 4-cyclohexanediamine, 4,4′-methylenebis (2-methylcyclohexylamine), 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 4,4′-methylenebis (cyclohexylamine) ), Bis (aminomethyl) Ruborunan, isophorone diamine, 3 (4), 8 (9) - bis (aminomethyl) tricyclo [5.2.1.0 ^2,6] decane, 3-amino-benzylamine, 4-amino-benzylamine, and the like Can be mentioned.

  The cross-linking reaction between the copolymer and the diamine includes, for example, a first step in which a copolymer and a diamine are reacted to form a polyamic acid, and a second step in which an imide bond is formed by a dehydration reaction of the polyamic acid. May be implemented.

  The first step may be, for example, a step of obtaining a polyamic acid by reacting a copolymer and a diamine in a solvent. The reaction temperature may be, for example, -20 to 200 ° C, and the reaction time may be, for example, 0.1 to 100 hours.

  The solvent used in the first step may be any solvent that can dissolve the copolymer and diamine. Moreover, it is preferable that a solvent is a solvent which can melt | dissolve the polyamic acid to produce | generate. Examples of the solvent include dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), γ-butyrolactone, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), tetramethylurea. 1,3-dimethyl-2-imidazolidinone, phenol, p-chlorophenol, pyridine, cyclopentanone, cyclohexanone and the like can be preferably used.

  The amount of diamine to be reacted with the copolymer may be, for example, 0.05 equivalents or more, and 0.5 equivalents or more based on the content of unsaturated dicarboxylic anhydride units in the copolymer. Is more preferable. The amount of diamine may be 1.5 equivalents or less, and more preferably 1.0 equivalents or less, based on the content of unsaturated dicarboxylic anhydride units in the copolymer, for example.

  In the first step, a reaction solution containing a polyamic acid may be obtained. In one aspect, the polyamic acid may be recovered from the reaction solution, and the recovered polyamic acid may be subjected to the second step. Moreover, in another aspect, after apply | coating this reaction liquid on a board | substrate and forming the coating film of a polyamic acid, you may implement a 2nd process.

  In the second step, an imide bond is formed by dehydration reaction of polyamic acid to obtain an imide cross-linked resin.

  The dehydration reaction may be performed, for example, by heating a polyamic acid. The reaction temperature of the dehydration reaction may be, for example, 100 to 400 ° C., and the reaction time may be, for example, 0.1 to 100 hours.

  In addition, the aspect of a crosslinking reaction is not limited to the above. For example, the crosslinking reaction may be a reaction in which a copolymer and a diamine are reacted using a dehydration catalyst to form an imide bond in one step. Examples of the dehydration catalyst include pyridine, 2-hydroxypyridine, triethylamine, imidazole, N-methylpiperidine and the like. The crosslinking reaction may be performed in the presence of a dehydrating agent that traps generated water. Examples of the dehydrating agent include acetic anhydride, propionic anhydride, and trifluoroacetic anhydride.

  The imide crosslinked resin according to this embodiment has an imide bond formed by a reaction between an acid anhydride in the copolymer and an amino group in the diamine. The imide cross-linked resin according to the present embodiment has sufficient light transmittance and good heat resistance by including in the molecule a cyclic structure derived from a cyclic olefin and a cross-linked structure via an imide bond. For this reason, the imide bridge | crosslinking type resin which concerns on this embodiment can be utilized suitably as a resin material for surface protection films.

(Transparent film)
The transparent film according to this embodiment includes the imide cross-linked resin. The transparent film which concerns on this embodiment can be used suitably as a film base material for surface protection films, for example. In addition, in this specification, a transparent film shows the film whose visible light transmittance ( _T450nm ) is 60% or more.

The visible light transmittance (T _{450 nm} ) of the transparent film is preferably 80% or more, and more preferably 85% or more.

  The thickness of the transparent film is not particularly limited, and may be, for example, 1 μm or more, 10 μm or more, 500 μm or less, or 1000 μm or less.

  The transparent film may further contain components other than the imide crosslinked resin. For example, the transparent film may further contain an antioxidant, a light stabilizer, an antistatic agent, a lubricant, a flame retardant, a plasticizer, a clarifying agent, a nucleating agent, a filler, and the like.

  A preferred embodiment of the method for producing a transparent film will be described below.

  The manufacturing method of the transparent film which concerns on this aspect is a preparatory process which prepares the coating liquid containing the polyamic acid which is a reaction material of a copolymer and diamine, apply | coats a coating liquid on a board | substrate, and contains a polyamic acid The coating process which forms the coating film to perform, and the heating process of heating a coating film and obtaining the transparent film containing imide bridge | crosslinking type resin may be provided.

  In the preparation step, for example, the copolymer and diamine are reacted in a solvent to obtain a reaction solution containing polyamic acid, and the reaction solution may be used as a coating solution. Alternatively, polyamic acid may be recovered from the reaction solution, and the recovered polyamic acid may be dissolved in a solvent to obtain a coating solution.

  In the coating step, a coating solution is formed on the substrate to form a coating film. The coating method is not particularly limited, and a known coating method (for example, spin coating method, bar coater method, slit method, die coating method, etc.) may be used.

  In the coating step, the solvent may be removed after coating the coating solution. The method for removing the solvent is not particularly limited, and a known removal method (for example, heating under reduced pressure, heating under normal pressure, heating on a hot plate, heating under a hot air current, drying under an air current, far infrared heating) Etc.) may be used.

  The substrate is not particularly limited as long as it has a surface capable of forming a coating film having a desired shape. Examples of the substrate include a glass substrate; a metal foil substrate such as copper and aluminum; a metal belt substrate such as steel and stainless steel; a resin sheet substrate such as polytetrafluoroethylene, PPS, PET, acrylic resin, polyethylene, polypropylene, and polystyrene; Etc. can be used suitably.

  In the heating step, the coating film is heated to advance the dehydration reaction of the polyamic acid to obtain a transparent film containing an imide cross-linked resin. The heating temperature may be a temperature at which the dehydration reaction of the polyamic acid proceeds, and may be, for example, 100 to 400 ° C, preferably 200 to 300 ° C. The heating time may be, for example, 0.1 to 100 hours, and preferably 1 to 10 hours.

(Surface protection film)
The surface protective film which concerns on this embodiment is provided with the said transparent film and the metal vapor deposition layer provided on the at least one surface of the transparent film. The transparent film contains an imide cross-linked resin and is excellent in heat resistance. For this reason, in this embodiment, even when a metal is vapor-deposited on a transparent film, the expansion, distortion, etc. by the heat | fever of a transparent film are fully suppressed, and the surface protection film which has favorable light transmittance is obtained.

  A metal vapor deposition layer is a metal thin layer formed by vapor deposition on the transparent film. The metal may be, for example, aluminum, silicon, etc., and may be a metal oxide thereof. The vapor deposition method is not particularly limited, and a known vapor deposition method can be used.

  The thickness of the metal vapor deposition layer may be 1-1000 nm, for example, and may be 100-500 nm.

  The surface protective film which concerns on this embodiment can be used suitably for surface protection, such as a display of a portable information terminal, a touch panel, a display for personal computers, a display for television, a digital signage, for example.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to an Example.

[Example 1]
(1) Synthesis of copolymer (A-1) Copolymer (A-1) was obtained by alternating copolymerization of norbornene and maleic anhydride. The charging ratio of norbornene and maleic anhydride was 1: 1 (molar ratio), and the polymerization reaction was carried out using tetrahydrofuran (THF) with azobisisobutyronitrile (AIBN) as a radical polymerization initiator at room temperature for 24 hours. Performed under conditions. The amount of AIBN used was 1.9 mol% with respect to the total amount of monomer components.

  More specifically, 2000 mg of norbornene and 2080 mg of maleic anhydride were dissolved in 3 mL of THF, 60 mg of AIBN was added as a radical polymerization initiator, and the reaction was performed at 60 ° C. for 24 hours. After reprecipitation purification into diethyl ether, 2650 mg of copolymer (A-1) was obtained as a white powder.

The number average molecular weight Mn of the obtained copolymer (A-1) was 4.8 × 10 ³ , and the molecular weight distribution Mw / Mn was 1.7. The number average molecular weight Mn and the molecular weight distribution Mw / Mn were measured by the following methods.

<Measurement of number average molecular weight Mn and weight average molecular weight Mw>
The number average molecular weight Mn and the weight average molecular weight Mw were measured by the GPC measurement method under the following conditions.
Equipment: “RID-10A / CBM-20A / DGU-20A3, manufactured by Shimadzu Corporation
LC-20AD / DPD-M20A / CTO-20A "
Column: “TSKgel superHM-N” manufactured by Tosoh Corporation
Detector: Differential refractive index detector (RI detector / built-in)
Solvent: Chloroform Temperature: 40 ° C
Flow rate: 0.3 mL / min Injection volume: 20 μL
Concentration: 0.1% by weight
Calibration sample: Monodisperse polystyrene Calibration method: Polystyrene

(2) Production of Imide Crosslinked Resin (A-1-1) 1 mL of dimethylacetamide solution (concentration 25 mg / mL) of diamine is added to 1 mL of dimethylacetamide solution (concentration 100 mg / mL) of copolymer (A-1). The resulting mixture was stirred and reacted at room temperature for 20 hours to obtain a coating solution containing polyamic acid. As the diamine, 4,4′-diaminodiphenyl ether is used, and the addition amount of the diamine is 1 equivalent with respect to the maleic anhydride unit in the copolymer (that is, 0.5% of diamine with respect to 1 mole of maleic anhydride unit). Mol).
Next, 500 μL of the obtained coating solution was drop-cast on a 250 mm square glass substrate and dried at 100 ° C. for 1 hour to obtain a self-supporting film. The obtained self-supporting film was heated at 200 ° C. under a vacuum of 1 mmHg for 24 hours to imidize the polyamic acid to obtain a transparent film containing an imide-crosslinked resin (A-1-1).

The obtained imide crosslinked resin (A-1-1), was measured 10% weight reduction temperature _{(T 10)} in the following manner. As a _{result, T 10} is 386 ° C., high heat resistance was confirmed. Moreover, when the visible light transmittance _| permeability ( _T450nm ) of the transparent film was measured with the following method, _T450nm was 82%.

<Measurement method of 10% weight loss temperature>
A 10% weight reduction temperature was measured using a thermogravimetric analyzer (“Thermo plus Evo TG8120” manufactured by Rigaku Corporation). While flowing nitrogen gas in a nitrogen gas atmosphere, the scanning temperature was set to 30 ° C. to 500 ° C., and the rate of temperature increase was 10 ° C./min. The temperature was determined by measuring the temperature at which the weight of the sample used was reduced by 10%.

<Measurement method of light transmittance>
Using a spectrophotometer Jasco V-670 spectrophotometer as a measuring device, the transmittance of the sample with respect to light with a wavelength of 280 to 800 nm was measured, and the transmittance with respect to light with a wavelength of 450 nm was obtained.

[Example 2]
(1) Production of Imide Crosslinked Resin (A-1-2) As a diamine, except that 1.6 mL of DMAc solution (concentration 25 mg / mL) of 2,2′-bis (trifluoromethyl) benzidine was used, A transparent film containing an imide crosslinked resin (A-1-2) was produced in the same manner as in Example 1.

_{T 10} is 379 ° C. of the imide-crosslinked resin (A-1-2), _{T 450nm} transparent film was 74%.

[Example 3]
(1) Production of Imide Crosslinked Resin (A-1-3) DMAc of 3 (4), 8 (9) -bis (aminomethyl) tricyclo [5.2.1.0 ^2,6 ] decane as diamine A transparent film containing an imide-crosslinked resin (A-1-3) was produced in the same manner as in Example 1 except that 1 mL of the solution (concentration 25 mg / mL) was used.

The T _{10 of the} imide cross-linked resin (A-1-3) and the T _{450 nm} of the transparent film both showed substantially the same values as in Example 2.

[Example 4]
(1) Production of Imide Crosslinked Resin (A-1-4) To 1 mL of a THF solution (concentration 100 mg / mL) of copolymer (A-1), DMS-A12 (aminopropyl-terminated dimethylsiloxane, molecular weight) manufactured by Gelest 900 mL to 1000) of a THF solution (concentration: 37 mg / mL) was added and reacted by stirring at room temperature for 20 hours to obtain a coating solution containing polyamic acid. The amount of diamine added was about 0.45 equivalent.
Next, 1 mL of the obtained coating solution was drop-cast on a 2 cm square Teflon (registered trademark) dish and dried at room temperature for 1 hour to obtain a self-supporting film. The obtained self-supporting film was heated at 200 ° C. for 24 hours under a vacuum of 1 mmHg to imidize the polyamic acid to obtain a transparent film containing an imide-crosslinked resin (A-1-4).

_{T 10} is 352 ° C. of the imide-crosslinked resin (A-1-4), _{T 450nm} transparent film was 60%.

[Example 5]
(1) Production of Imide Crosslinked Resin (A-1-5) To 1 mL of a THF solution (concentration 100 mg / mL) of copolymer (A-1), amino-modified silicone oil X-22-9409 (Shin-Etsu Chemical Co., Ltd.) 1 mL of a THF solution (concentration 57 mg / mL) of aminophenyl-terminated dimethylsiloxane (molecular weight 1340) was added and reacted by stirring at room temperature for 20 hours to obtain a coating solution containing polyamic acid. The amount of diamine added was about 0.3 equivalent.
Next, 1 mL of the obtained coating solution was drop-cast on a 2 cm square Teflon (registered trademark) dish and dried at room temperature for 1 hour to obtain a self-supporting film. The obtained self-supporting film was heated at 200 ° C. under a vacuum of 1 mmHg for 24 hours to imidize the polyamic acid to obtain a transparent film containing an imide-crosslinked resin (A-1-5).

_{T 10} is 359 ° C. of the imide-crosslinked resin (A-1-5), _{T 450nm} transparent film was 84%.

[Example 6]
(1) Synthesis of copolymer (A-2) Copolymer (A-2) was obtained by copolymerization of norbornene, maleic anhydride and N-ethylmaleimide. The charging ratio of norbornene, maleic anhydride and N-ethylmaleimide was 3: 1: 2. The polymerization reaction was carried out in THF at room temperature for 24 hours using AIBN as a radical polymerization initiator. The amount of AIBN used was 1.6 mol% with respect to the total amount of monomer components.

  More specifically, 2000 mg of norbornene, 710 mg of maleic anhydride, and 1780 mg of N-ethylmaleimide were dissolved in 3 mL of THF, 60 mg of AIBN was added as a radical polymerization initiator, and the reaction was performed at 60 ° C. for 24 hours. After reprecipitation purification into diethyl ether, 3340 mg of copolymer (A-2) was obtained as a white powder.

The number average molecular weight Mn of the obtained copolymer (A-2) was 4.7 × 10 ³ , and the molecular weight distribution Mw / Mn was 1.7.

(2) Production of Imide Crosslinked Resin (A-2-1) To 1 mL of γ-butyrolactone solution (concentration 100 mg / mL) of copolymer (A-2), γ-butyrolactone solution of diamine (concentration 25 mg / mL) 1 mL was added and stirred at room temperature for 20 hours to react to obtain a coating solution containing polyamic acid. As the diamine, 4,4′-diaminodiphenyl ether was used, and the amount of the diamine added was 0.5 equivalent to the maleic anhydride unit in the copolymer.
Next, 500 μm of the obtained coating solution was drop cast on a 250 mm square glass substrate and dried at 130 ° C. for 1 hour to obtain a self-supporting film. The obtained self-supporting film was heated at 200 ° C. under a vacuum of 1 mmHg for 24 hours to imidize the polyamic acid to obtain a transparent film containing an imide-crosslinked resin (A-2-1).

T ₁₀ of the imide crosslinked resin (A-2-1) was 385 ° C., and T _{450 nm} of the transparent film was 81%.

  The obtained transparent film was cut into 7 mm × 25 mm to prepare a test piece, and a dynamic viscoelasticity test was performed. As a result, the storage elastic modulus of the test piece was 2.1 GPa, Tg was 299 ° C., and it was confirmed that the specimen had high thermal stability and mechanical strength.

[Reference Example 1]
(1) Synthesis of copolymer (A-3) A copolymer (A-3) was obtained by alternating copolymerization of dicyclopentadiene and maleic anhydride. The charging ratio of dicyclopentadiene and maleic anhydride was 1: 1 (molar ratio), and the polymerization reaction was carried out using azobisisobutyronitrile (AIBN) in tetrahydrofuran (THF) as a radical polymerization initiator at room temperature, 24 Performed under time conditions. The amount of AIBN used was 2.1 mol% with respect to the total amount of monomer components.

  More specifically, 2000 mg of dicyclopentadiene and 1490 mg of maleic anhydride were dissolved in 3 mL of THF, 60 mg of AIBN was added as a radical polymerization initiator, and the reaction was performed at 60 ° C. for 24 hours. After reprecipitation purification into diethyl ether, 1100 mg of copolymer (A-3) was obtained as a white powder.

The number average molecular weight Mn of the obtained copolymer (A-3) was 3.3 × 10 ³ , and the molecular weight distribution Mw / Mn was 1.8. It was confirmed that the obtained copolymer (A-3) was crosslinked with diamine in the same manner as in Examples 1-6.

[Reference Example 2]
(1) Synthesis of copolymer (A-4) Copolymer (A-4) was obtained by alternating copolymerization of ethenylnorbornene and maleic anhydride. The charging ratio of ethenylnorbornene and maleic anhydride was 1: 1 (molar ratio), and the polymerization reaction was carried out using azobisisobutyronitrile (AIBN) in tetrahydrofuran (THF) as a radical polymerization initiator at room temperature, 24 Performed under time conditions. The amount of AIBN used was 2.3 mol% with respect to the total amount of monomer components.

  More specifically, 2000 mg of ethenylnorbornene and 1640 mg of maleic anhydride were dissolved in 3 mL of THF, 60 mg of AIBN was added as a radical polymerization initiator, and the reaction was performed at 60 ° C. for 24 hours. After reprecipitation purification into diethyl ether, 3030 mg of copolymer (A-4) was obtained as a white powder.

The number average molecular weight Mn of the obtained copolymer (A-4) was 6.6 × 10 ³ , and the molecular weight distribution Mw / Mn was 2.0. It was confirmed that the obtained copolymer (A-4) was crosslinked with diamine in the same manner as in Examples 1-6.

[Comparative Example 1]
The copolymer obtained in Example 1 (A-1) results subjected to T ₁₀ measured without crosslinking with diamines, T ₁₀ was 144 ° C.. Thereby, it was confirmed that the heat resistance is remarkably improved by crosslinking with diamine.

Claims (5)

  An imide crosslinked resin obtained by crosslinking a copolymer having a cyclic olefin unit and an unsaturated dicarboxylic anhydride unit with a diamine.   The imide crosslinked resin according to claim 1, wherein the cyclic olefin unit has a norbornane skeleton.   The imide crosslinked resin according to claim 1 or 2, wherein the unsaturated dicarboxylic anhydride unit includes a maleic anhydride unit.   The transparent film containing the imide bridge | crosslinking type resin as described in any one of Claims 1-3. The transparent film according to claim 4,
A metal vapor deposition layer provided on at least one surface of the transparent film;
A surface protective film.