JP6707741B2 - Imide cross-linking resin, transparent film and surface protection film - Google Patents

Description

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

In recent years, with the spread of portable information terminals and the like, there is an increasing demand for a surface protection film that protects the display surface. For example, Patent Document 1 discloses an organic light emitting display device in which a cover window is arranged on a polarizing plate or a touch panel.

JP, 2010-232162, A

The surface protection 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 the present invention is to provide an imide cross-linking type resin which has good heat resistance and can be suitably used as a resin material for a surface protection film. Another object of the present invention is to provide a transparent film which contains an imide cross-linking resin and can be suitably used as a film substrate for a surface protection film. Another object of the present invention is to provide a surface protection film provided with the transparent film.

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

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

In one aspect, the unsaturated dicarboxylic acid anhydride units may include maleic anhydride units.

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

Yet another aspect of the present invention relates to a surface protective film including 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 transparent film which contains the said imide bridge|crosslinking type resin and is suitable as a film base material for surface protection films, and the surface protection film provided with the said transparent film are provided.

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

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

In the present 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 said to be a copolymer having a structural unit derived from a cyclic olefin and a structural unit derived from an unsaturated dicarboxylic acid anhydride, and a monomer component containing a cyclic olefin and an unsaturated dicarboxylic acid anhydride. It can be said that it is a copolymer.

The imide cross-linking resin according to the present embodiment has an imide bond formed by the reaction between the acid anhydride in the copolymer and the amino group in the diamine. The imide cross-linking resin according to the present embodiment has sufficient light transmittance and good heat resistance by having a cyclic olefin-derived ring structure and a cross-linking structure via an imide bond in the molecule. Therefore, the imide cross-linking resin according to this embodiment can be suitably used as a resin material for a surface protection film.

<Copolymer>
The copolymer in the present embodiment is a polymer that has a cyclic olefin unit and an unsaturated dicarboxylic acid anhydride unit and is crosslinkable with a diamine.

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

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

The number average molecular weight Mn of the copolymer may be, for example, 190 or more, preferably 1000 or more, and 3000 or more. Increasing the number average molecular weight Mn of the copolymer tends to further improve the heat resistance of the imide crosslinkable resin. The number average molecular weight Mn of the copolymer may be, for example, 500,000 or less, preferably 10,000 or less, and 7,000 or less. By decreasing the number average molecular weight Mn of the copolymer, the reaction rate of the crosslinking reaction with the 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-linking resin is further improved, and the volatile content in the imide cross-linking resin tends to be reduced.

In addition, in this specification, the number average molecular weight Mn and weight average molecular weight Mw of a copolymer show the value measured on condition of the following by a GPC measuring method.
Equipment: Shimadzu RID-10A/CBM-20A/DGU-20A3
LC-20AD/DPD-M20A/CTO-20A"
Column: "TSK gel super HM-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 containing carbon atoms constituting the ring structure, and is polymerizable 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 the ring structure is incorporated in the main chain of the copolymer, the shape and motility of the main chain are limited, and the imide cross-linking resin further excellent in heat resistance and optical properties. 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 norbornene skeleton, norbornadiene skeleton, bicyclo[2.2.2]oct-2-ene skeleton, bicyclo[2.2.2]octa-2,5-diene skeleton, diene 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. Moreover, 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 a structure 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 hinder 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, an alkoxycarbonyl group, or the like. 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, and 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. The alkyl group may have, for example, 1 to 30 carbon atoms, and preferably 1 to 10 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, tert-butyl and the like.

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

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 aromatic hydrocarbon. Examples of the aryl group include a phenyl group, a naphthyl group, an anthracenyl group and the like.

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

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

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, and a tert-butoxycarbonyl group.

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

Specific examples of the cyclic olefin include, for example, acenaphthylene, 5-acetyl-2-norbornene bicyclo[3.2.1]oct-2-ene, and [bicyclo[2.2.1]hept-5-ene-2-. Il]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-2,3-dicarboxylic acid 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]do De-4-ene, 4-vinyl-1-cyclohexene, 5-vinylbicyclo[2.2.1]hept-2-ene, tricyclopentadiene, dimethanobenzindene, dimethanofluorene, α-pinene, β- Examples include pinene and limonene.

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 constituent unit obtained by reacting part or all of the carbon-carbon double bond of the cyclic olefin in a polymerization reaction, and a 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 with single bonds.

It is preferable that at least a part of the ring structure of the cyclic olefin unit constitutes the main chain of the copolymer. Thereby, the shape and mobility of the main chain of the copolymer are controlled by the ring structure of the cyclic olefin unit, and an imide cross-linking resin having more excellent heat resistance and optical properties can be obtained.

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

Examples of unsaturated dicarboxylic acid anhydrides include maleic anhydride, citraconic anhydride, itaconic anhydride, 2,3-dimethylmaleic anhydride, 2-(2-carboxyethyl)-3-methylmaleic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, phenyl maleic anhydride, 2,3-diphenyl maleic anhydride, allyl succinic anhydride, (2-methyl-2-propenyl) succinic anhydride, 2-buten-1-ylsuccinic anhydride, cis-4-cyclohexene-1,2-dicarboxylic acid anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, bicyclo[2.2.2]oct- Examples thereof include 5-ene-2,3-dicarboxylic acid anhydride.

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 two R ¹ may be the same 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. As a result, an imide cross-linking resin having more 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 of R ¹ may be linear, branched or cyclic. The alkyl group may have, for example, 1 to 30 carbon atoms, and preferably 1 to 10 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, tert-butyl and the like.

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

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

R ¹ is preferably a hydrogen atom, an alkyl group or a halogenated alkyl group, and more preferably a hydrogen atom or an alkyl group. Further, from the viewpoint of excellent reactivity with a cyclic olefin and facilitating the production of a 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 contained in succinic anhydride are removed.

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

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

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 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 of R ² may be linear, branched or cyclic. The alkyl group may have, for example, 1 to 30 carbon atoms, and preferably 1 to 10 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, tert-butyl and the like.

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

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

R ² 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 the unsaturated dicarboxylic acid anhydride and facilitating the 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 hinder 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, and 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 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, a propylthio group and the like.

The aryloxy group and the arylthio group are groups represented by —OR″ and —SR″ (R″ represents an aryl group), respectively. As the aryl group of R″, the same examples as described above can be used. 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 according to the present embodiment may further have a structural unit other than the above. For example, the copolymer may further have a structural unit derived from a bismaleimide-based compound having two maleimide groups.

Examples of the bismaleimide-based compound include 4,4′-bismaleimide diphenylmethane, 1,6-bis(maleimide)hexane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, 1,4-bis. (Maleimide)butane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 1,2-bis(maleimido)ethane, N,N′-1,4-phenylene dimaleimide, N,N′ -1,3-Phenylene dimaleimide etc. are mentioned.

Moreover, the copolymer may further have a structural unit derived from an olefin compound capable of alternating copolymerization with an unsaturated dicarboxylic acid 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 a monomer component containing 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, for example, radical polymerization.

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, and redox initiator (hydrogen peroxide and Examples thereof include iron (II) salts, persulfates and sodium hydrogen sulfite, triethylborane (Et ₃ B), diethyl zinc (Et ₂ Zn) and the like.

The amount of the radical polymerization initiator used may be, for example, 0.1 to 10 mol% and preferably 1 to 5 mol% based on the total amount of the monomer components.

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), γ-butyrolactone. , Cyclopentanone, cyclohexanone, tetramethylurea, 1,3-dimethyl-2-imidazolidinone, glyme solvent such as diglyme, cellosolve solvent such as ethyl cellosolve, glycol ester solvent such as propylene glycol monomethyl ether acetate, A glycol ether solvent such as propylene glycol monomethyl ether can be preferably used.

The conditions of the polymerization reaction are not particularly limited, and 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-linking resin according to the present embodiment is a cross-linking product obtained by cross-linking the above copolymer with a diamine, and has an imide bond formed by the reaction between the acid anhydride and the diamine in the copolymer.

In the present embodiment, some or all of the unsaturated dicarboxylic acid anhydride units in the copolymer may react with the 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 crosslinking resin is preferably 90 mol% or less, and 70 mol% or less. It is more preferable that the amount is 50 mol% or less.

The diamine may be a compound having two amino groups capable of reacting with the acid anhydride in the copolymer to form an imide bond.

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

Examples of the aromatic diamine include compounds having a structure 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 hinder the crosslinking reaction. The substituent is, for example, a halogen atom, an alkyl group, a halogenated alkyl group, an aryl group, a sulfo group, an alkoxy group, an aryloxy group, a silyl group, a hydroxy group, a thiol group, an alkylthio group, an arylthio group, a nitrile group, a ketone group. It 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 those mentioned above.

The ketone group is a group represented by -COR' (R' represents an alkyl group, an aryl group or an aralkyl group), and the alkyl group, the aryl group and the aralkyl group of R'include the same examples as described above. Be done. Examples of the ketone group include a methylcarbonyl group, a phenylcarbonyl group, a benzylcarbonyl group and the like.

The divalent group for Q ¹ is not particularly limited as long as it does not hinder the crosslinking reaction. Specific examples of the divalent _{group, -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 a structure 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 hinder the crosslinking reaction. The substituent is, for example, a halogen atom, an alkyl group, a halogenated alkyl group, an aryl group, a sulfo group, an alkoxy group, an aryloxy group, a silyl group, a hydroxy group, a thiol group, an alkylthio group, an arylthio group, a nitrile group, a ketone group. It 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 above.

The divalent group in Q ² is not particularly limited as long as it does not hinder the crosslinking reaction. Specific examples of the divalent _{group, -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.

Further, the diamine may be, for example, a polysiloxane-based diamine having an amino group introduced at the terminal or side chain of polysiloxane. The molecular weight of the polysiloxane-based 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-phenylenediamine, 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-methyl) Aniline), 4,4'-methylenebis(2,6-diethylaniline), 4,4''-diamino-p-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)fluore ,9,9-bis(4-amino-3-chlorophenyl)fluorene, 9,9-bis(4-amino-3-fluorophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl) Fluorene, 9,9-bis(3-amino-4-hydroxyphenyl)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-phenylene bis(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'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 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)hexafluoropropane, 2,2′ -Bis(trifluoromethyl)benzidine, 4,4'-diaminostilbene, 3,6-diaminocarbazole, 2,6-diaminoanthraquinone, 3,9-bis[2-(3,5-diamino-2,4,4) 6-Triazaphenyl)ethyl]-2,4,8,10-tetraoxaspiro[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, triethylenetetraamine, 3,3′ -Diaminodipropylamine, 2,2'-diamino-N-methyldiethylamine, 3,3'-diamino-N-methyldipropylamine, N,N'-bis(2-aminoethyl)-1,3-propane Diamine, N,N'-bis(3-aminopropyl)ethylenediamine, N,N'-bis(3-aminopropyl)-1,4-butanediamine, 2,2'-thiobis(ethylamine), m-xylylenediene Amine, p-xylylenediamine, cis-1,3-bis(aminomethyl)cyclohexane, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, Shin-Etsu Chemical amino-modified silicone oil (for example, X-22 -1660B-3 (Mw: 4400), X-22-161B (Mw: 3000), X-22-161A (Mw: 1600) X-22-9409 (Mw: 1340), etc.), Gelest dimethylsiloxane type diamine (for example, DMS-A11, DMS-A12, DMS-A15, DMS-A21, DMS-A31, DMS-A32, DMS-A35), 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)norbornane, isophoronediamine, 3(4),8(9)-bis( Aminomethyl)tricyclo[5.2.1.0 ^2,6 ]decane, 3-aminobenzylamine, 4-aminobenzylamine, and the like.

The crosslinking reaction between the copolymer and the diamine, for example, by the first step of reacting the copolymer and the diamine to form a polyamic acid, and the second step of forming an imide bond by the dehydration reaction of the polyamic acid, May be implemented.

The first step may be, for example, a step of reacting a copolymer and a diamine in a solvent to obtain a polyamic acid. 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 the diamine. Further, the solvent is preferably a solvent capable of dissolving the generated polyamic acid. Examples of the solvent include dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), γ-butyrolactone, N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), tetrahydrofuran (THF), and tetramethylurea. , 1,3-dimethyl-2-imidazolidinone, phenol, p-chlorophenol, pyridine, cyclopentanone, cyclohexanone and the like can be preferably used.

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

In the first step, a reaction solution containing polyamic acid may be obtained. In one embodiment, the polyamic acid may be recovered from this reaction solution and the recovered polyamic acid may be subjected to the second step. In another aspect, the second step may be carried out after applying the reaction solution onto the substrate to form a coating film of polyamic acid.

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

The dehydration reaction may be carried out, for example, by heating the 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.

The mode of the crosslinking reaction is not limited to the above. For example, the crosslinking reaction may be a reaction in which the copolymer and the 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. Further, the crosslinking reaction may be carried out in the presence of a dehydrating agent that traps the generated water, and examples of the dehydrating agent include acetic anhydride, propionic anhydride, trifluoroacetic anhydride and the like.

The imide cross-linking resin according to the present embodiment has an imide bond formed by the reaction between the acid anhydride in the copolymer and the amino group in the diamine. The imide cross-linking resin according to the present embodiment has a ring structure derived from a cyclic olefin and a cross-linking structure via an imide bond in the molecule, and thus has sufficient light transmittance and good heat resistance. Therefore, the imide cross-linking resin according to this embodiment can be suitably used as a resin material for a surface protection film.

(Transparent film)
The transparent film according to this embodiment contains the imide cross-linking resin. The transparent film according to the present embodiment can be suitably used, for example, as a film base material for a surface protection film. In addition, in this specification, a transparent film refers to a film having a visible light transmittance (T _{450 nm} ) of 60% or more.

The visible light transmittance (T _450nm ) of the transparent film is preferably 80% or more, 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, and 500 μm or less or 1000 μm or less.

The transparent film may further contain components other than the imide crosslinkable 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.

One suitable aspect of the method for producing a transparent film will be described below.

The method for producing a transparent film according to the present embodiment, a preparatory step of preparing a coating liquid containing a polyamic acid that is a reaction product of a copolymer and a diamine, and coating the coating liquid on a substrate, containing a polyamic acid. And a heating step of heating the coating film to obtain a transparent film containing an imide cross-linking resin.

In the preparation step, for example, the copolymer and the diamine may be reacted in a solvent to obtain a reaction liquid containing a polyamic acid, and the reaction liquid may be used as a coating liquid. Further, the coating solution may be obtained by recovering the polyamic acid from the reaction solution and dissolving the recovered polyamic acid in a solvent.

In the coating step, the coating liquid is coated 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 liquid. The method of removing the solvent is not particularly limited, and known removal methods (for example, heating under reduced pressure, heating under normal pressure, heating with a hot plate, heating under a hot air stream, drying under an air stream, far infrared heating). Etc.) may be used.

The substrate is not particularly limited as long as it has a surface on which a coating film having a desired shape can be formed. 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; And the like can be preferably used.

In the heating step, the coating film is heated to promote the dehydration reaction of the polyamic acid to obtain a transparent film containing the imide cross-linking 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, preferably 1 to 10 hours.

(Surface protection film)
The surface protection film according to the present embodiment includes the transparent film and a metal vapor deposition layer provided on at least one surface of the transparent film. The transparent film contains an imide cross-linking resin and has excellent heat resistance. Therefore, in the present embodiment, even when a metal is vapor-deposited on the transparent film, expansion and distortion of the transparent film due to heat are sufficiently suppressed, and a surface protective film having good light transmittance can be obtained.

The metal vapor deposition layer is a thin metal layer formed by vapor deposition on a transparent film. The metal may be, for example, aluminum or silicon, or may be a metal oxide of these. 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, for example, 1 to 1000 nm, or 100 to 500 nm.

The surface protective film according to the present embodiment can be suitably used for surface protection of, for example, a display of a personal digital assistant, a touch panel, a display for personal computers, a display for television, a digital signage, and the like.

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

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the examples.

[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 set to 1:1 (molar ratio), and the polymerization reaction was carried out at room temperature for 24 hours by using azobisisobutyronitrile (AIBN) as a radical polymerization initiator in tetrahydrofuran (THF). I went under the 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 carried out at 60° C. for 24 hours. After reprecipitation purification with 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: Shimadzu RID-10A/CBM-20A/DGU-20A3
LC-20AD/DPD-M20A/CTO-20A"
Column: "TSK gel super HM-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 cross-linking resin (A-1-1) 1 mL of a dimethylacetamide solution of diamine (concentration 25 mg/mL) was added to 1 mL of a dimethylacetamide solution (concentration 100 mg/mL) of the copolymer (A-1). The mixture was added and reacted by stirring at room temperature for 20 hours to obtain a coating solution containing polyamic acid. As the diamine, 4,4′-diaminodiphenyl ether was used, and the addition amount of the diamine was 1 equivalent to the maleic anhydride unit in the copolymer (that is, 0.5 mol of the diamine relative to 1 mol of the maleic anhydride unit). Mol).
Next, 500 μL of the obtained coating liquid 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 free-standing 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 the imide cross-linking resin (A-1-1).

The 10% weight loss temperature (T ₁₀ ) of the obtained imide crosslinked resin (A-1-1) was measured by the following method. As a result, T ₁₀ was 386° C., and high heat resistance was confirmed. Moreover, when the visible light transmittance (T _450nm ) of the transparent film was measured by the following method, T _450nm was 82%.

<Method of measuring 10% weight loss temperature>
The 10% weight loss temperature was measured using a thermogravimetric analyzer (“Thermo plus Evo TG8120” manufactured by Rigaku Corporation). In a nitrogen gas atmosphere, while flowing nitrogen gas, the scanning temperature was set to 30°C to 500°C, and the heating rate was 10°C/min. It was obtained by measuring the temperature at which the weight of the sample used was reduced by 10% by heating under the conditions of.

<Measuring method of light transmittance>
A spectrophotometer Jasco V-670 spectrophotometer was used as a measuring device to measure the transmittance of the sample for light having a wavelength of 280 to 800 nm, and the transmittance for light having a wavelength of 450 nm was obtained.

[Example 2]
(1) Production of imide cross-linking resin (A-1-2) Except that 1.6 mL of 2,2′-bis(trifluoromethyl)benzidine in DMAc (concentration 25 mg/mL) was used as the diamine, A transparent film containing the imide cross-linking resin (A-1-2) was produced in the same manner as in Example 1.

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

[Example 3]
(1) Production of imide cross-linked resin (A-1-3) As diamine, DMAc of 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0 ^2,6 ]decane A transparent film containing the imide cross-linking 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-linking resin (A-1-3) and the T _{450 nm} of the transparent film both showed almost the same values as in Example 2.

[Example 4]
(1) Production of imide cross-linked resin (A-1-4) 1 mL of a THF solution (concentration 100 mg/mL) of the copolymer (A-1) was added to Gelest DMS-A12 (aminopropyl-terminated dimethylsiloxane, molecular weight). 1 mL of a THF solution (concentration 37 mg/mL) of 900 to 1000) was added, and the mixture was stirred and reacted at room temperature for 20 hours to obtain a coating solution containing a polyamic acid. The amount of diamine added was about 0.45 equivalent.
Next, 1 mL of the obtained coating liquid was drop-cast on a Teflon (registered trademark) plate having a 2 cm square bottom surface and dried at room temperature for 1 hour to obtain a free-standing film. The obtained free-standing 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 the imide cross-linking resin (A-1-4).

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

[Example 5]
(1) Production of imide cross-linking resin (A-1-5) 1 mL of a THF solution (concentration 100 mg/mL) of the copolymer (A-1) was added to Shinetsu Chemical's amino-modified silicone oil X-22-9409 ( 1 mL of a THF solution (concentration 57 mg/mL) of aminophenyl-terminated dimethylsiloxane, molecular weight 1340) was added, and the mixture was stirred and reacted at room temperature for 20 hours to obtain a coating solution containing a polyamic acid. The amount of diamine added was about 0.3 equivalent.
Next, 1 mL of the obtained coating liquid was drop-cast on a Teflon (registered trademark) plate having a 2 cm square bottom surface and dried at room temperature for 1 hour to obtain a free-standing film. The obtained free-standing 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 the imide cross-linking resin (A-1-5).

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

[Example 6]
(1) Synthesis of Copolymer (A-2) Copolymer (A-2) was obtained by copolymerizing 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 carried out at 60° C. for 24 hours. After purification by reprecipitation in 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) Manufacture of imide cross-linking resin (A-2-1) 1 g of γ-butyrolactone solution (concentration 100 mg/mL) of copolymer (A-2) was added to γ-butyrolactone solution of diamine (concentration 25 mg/mL). 1 mL was added and reacted by stirring at room temperature for 20 hours to obtain a coating solution containing a polyamic acid. As the diamine, 4,4'-diaminodiphenyl ether was used, and the amount of the diamine added was 0.5 equivalent with respect to the maleic anhydride unit in the copolymer.
Next, 500 μm of the obtained coating liquid 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 free-standing 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 the imide cross-linking resin (A-2-1).

T ₁₀ of the imide cross-linking 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 and Tg was 299° C., and it was confirmed that the test piece had high thermal stability and mechanical strength.

[Reference Example 1]
(1) Synthesis of Copolymer (A-3) A copolymer (A-3) was obtained by alternate copolymerization of dicyclopentadiene and maleic anhydride. The charge ratio of dicyclopentadiene and maleic anhydride was set to 1:1 (molar ratio), and the polymerization reaction was carried out by using azobisisobutyronitrile (AIBN) as a radical polymerization initiator in tetrahydrofuran (THF) at room temperature and 24 I went under the condition of time. 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 carried out at 60° C. for 24 hours. After reprecipitation purification with 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 a diamine as in Examples 1 to 6.

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

More specifically, ethenyl norbornene 2000 mg and maleic anhydride 1640 mg were dissolved in THF 3 mL, 60 mg of AIBN was added as a radical polymerization initiator, and the reaction was carried out at 60° C. for 24 hours. After reprecipitation purification with 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 a diamine as in Examples 1 to 6.

[Comparative Example 1]
As a result of subjecting the copolymer (A-1) obtained in Example 1 to T ₁₀ measurement without crosslinking with diamine, T ₁₀ was 144° C. From this, it was confirmed that the heat resistance was significantly improved by the crosslinking with the diamine.

Claims (5)

Cyclic olefin emissions及 beauty Ri Na crosslinked with diamine copolymer of a monomer component containing an unsaturated dicarboxylic acid anhydride,
During the copolymer, the total amount of content of the cyclic olefin unit _C 1 for (mol), the content of the unsaturated dicarboxylic acid anhydride unit _C 2 (mol) and the content _C 3 of the maleimide based unit (mol) C _An imide cross-linking resin in which the ratio (C ₂ +C ₃ )/C _{1 of 2} +C ₃ (mol) is 0.5 to 2.0 . The cyclic olefin units having a norbornene Ne emissions skeleton, imide cross-linked resin according to claim 1. The imide cross-linking resin according to claim 1 or 2, wherein the unsaturated dicarboxylic acid anhydride unit includes a maleic anhydride unit. A transparent film containing the imide cross-linking resin according to claim 1. 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 comprising.