JP7621751B2 - Protective film and photosensitive resin composition for obtaining same - Google Patents

Description

The present invention relates to a protective film as a component of a panel such as a display or wiring board, for example, a protective film that can also be used as a condition setting for carrying out a subsequent process such as flattening after forming RGB pixels of a color filter, as necessary, and a photosensitive resin composition for obtaining the same. The protective film of the present invention is particularly effective when used in applications that involve bending during use, such as flexible displays.

Conventionally, display devices such as liquid crystal display devices, organic EL devices, and touch panels have been used as components of various displays, including large displays such as televisions and small displays such as mobile phones, personal computers, and smartphones. These components are laminates in which various functional layers such as TFTs, electrodes, and light-emitting layers are formed on a glass substrate. By replacing this glass substrate with a resin substrate, components that use conventional glass substrates can be made thinner, lighter, and more flexible. It is expected that this can be used to obtain flexible devices such as flexible displays.

The film can be widely used not only in display devices and displays, but also in transparent films and protective films formed for the purpose of surface protection and hard coating of lenses. As demand for thinner, lighter, and more flexible films grows, there is an increasing demand for various protective films to be resistant to bending.

Here, the use of resins has been promoted in place of the glass that has been used traditionally, but resins are inferior to glass in terms of dimensional stability, transparency, heat resistance, moisture resistance, film strength, etc., and various studies are being conducted. As such a resin material, polyimide has been widely studied so far due to its excellent heat resistance and dimensional stability (see Patent Documents 1 to 3).

Patent No. 6640223 Patent No. 6648076 JP 2018-193569 A

In the field of semiconductor device manufacturing, alkali-soluble resins having a fluorene skeleton have been used as photosensitive resins when forming resists or light-shielding films by photolithography. Such alkali-soluble resins having a fluorene skeleton have provided photosensitive resin compositions that are excellent in heat resistance, low gas generation, chemical resistance, and developability, particularly fine line formability. However, the cured product of the composition is relatively poor in flexibility, and it has been found that it is necessary to devise a photosensitive resin composition for applications requiring flexibility and toughness, such as color filters and touch panels for flexible displays.

The present invention was completed based on the new discovery that it is possible to form a protective film that exhibits elongation and toughness suitable for use as a protective film for color filters and touch panels of flexible displays, for example, by utilizing the advantages of alkali-soluble resins having a fluorene skeleton while improving their relatively disadvantageous points such as flexibility.

（ここで、Ｒ_１、Ｒ_２、Ｒ_３及びＲ_４は、独立に、水素原子、炭素数１～６のアルキル基、ハロゲン原子又はフェニル基である。Ｒ_５は炭素数２～２０の２価の脂肪族又は芳香族の炭化水素基であり、Ｒ_６は炭素数２～２２の２価のアルキレン基又はアルキルアリーレン基であり、Ｒ_７は水素原子又はメチル基である。ｐは０～６０の数である。Ｘは９，９－フルオレンジイル基であり、ｍは０～１０の数である。）
〔２〕膜厚が０．１～１００μｍであることを特徴とする〔１〕に記載の保護膜。
〔３〕前記〔１〕又は〔２〕に記載の保護膜であって、２個の重合性不飽和基を有する光重合性モノマーを１０質量％以上含有し、伸度が２％以上であることを特徴とする保護膜。
〔４〕伸度が１．５％以上の保護膜を形成するための感光性樹脂組成物であって、
（Ａ）以下の（Ａ－１）および／又は（Ａ－２）を１０～８８質量％〔ここで、（Ａ－１）は、下記一般式（１）で表されるエポキシ化合物に、（メタ）アクリル酸、下記一般式（２）で表される化合物又は下記一般式（３）で表される化合物を反応させて得られるエポキシ(メタ)アクリレート化合物であり、（Ａ－２）は、当該エポキシ(メタ)アクリレート化合物に、さらに多価カルボン酸又はその酸無水物を反応させて得られるエポキシ（メタ）アクリレート酸付加物である。〕、
（Ｂ）２個の重合性不飽和基を有する光重合性モノマーを１０～８８質量％、及び
（Ｃ）光重合開始剤を含有し、
前記Ａ成分とＢ成分との合計量１００質量部に対して、Ｃ成分が１～６０質量部含有されることを特徴とする感光性樹脂組成物。

（ここで、Ｒ_１、Ｒ_２、Ｒ_３及びＲ_４は、独立に、水素原子、炭素数１～６のアルキル基、ハロゲン原子又はフェニル基である。Ｒ_５は炭素数２～２０の２価の脂肪族又は芳香族の炭化水素基であり、Ｒ_６は炭素数２～２２の２価のアルキレン基又はアルキルアリーレン基であり、Ｒ_７は水素原子又はメチル基である。ｐは０～６０の数である。Ｘは９，９－フルオレンジイル基であり、ｍは０～１０の数である。）
〔５〕前記〔４〕に記載の感光性樹脂組成物を硬化させた保護膜を含む表示装置。 That is, the gist of the present invention is as follows.
[1] A protective film containing 5 mass % or more of the following (A-1) and/or (A-2) and having an elongation of 1.5% or more.
[Here, (A-1) is an epoxy (meth)acrylate compound obtained by reacting an epoxy compound represented by the following general formula (1) with (meth)acrylic acid, a compound represented by the following general formula (2) or a compound represented by the following general formula (3), and (A-2) is an epoxy (meth)acrylate acid adduct obtained by further reacting the epoxy (meth)acrylate compound with a polyvalent carboxylic acid or its acid anhydride.]

(wherein R ₁ , R ₂ , R ₃ and R ₄ are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom or a phenyl group; R ₅ is a divalent aliphatic or aromatic hydrocarbon group having 2 to 20 carbon atoms; R ₆ is a divalent alkylene group or alkylarylene group having 2 to 22 carbon atoms; R ₇ is a hydrogen atom or a methyl group; p is a number from 0 to 60; X is a 9,9-fluorenediyl group; and m is a number from 0 to 10.)
[2] The protective film according to [1], characterized in that the film thickness is 0.1 to 100 μm.
[3] The protective film according to [1] or [2], characterized in that it contains 10% by mass or more of a photopolymerizable monomer having two polymerizable unsaturated groups and has an elongation of 2% or more.
[4] A photosensitive resin composition for forming a protective film having an elongation of 1.5% or more,
(A) 10 to 88 mass % of the following (A-1) and/or (A-2) (wherein (A-1) is an epoxy (meth)acrylate compound obtained by reacting an epoxy compound represented by the following general formula (1) with (meth)acrylic acid, a compound represented by the following general formula (2) or a compound represented by the following general formula (3), and (A-2) is an epoxy (meth)acrylate acid adduct obtained by further reacting the epoxy (meth)acrylate compound with a polyvalent carboxylic acid or an acid anhydride thereof),
(B) 10 to 88% by mass of a photopolymerizable monomer having two polymerizable unsaturated groups, and (C) a photopolymerization initiator;
A photosensitive resin composition comprising 1 to 60 parts by mass of component C relative to 100 parts by mass of the total amount of components A and B.

(wherein R ₁ , R ₂ , R ₃ and R ₄ are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom or a phenyl group; R ₅ is a divalent aliphatic or aromatic hydrocarbon group having 2 to 20 carbon atoms; R ₆ is a divalent alkylene group or alkylarylene group having 2 to 22 carbon atoms; R ₇ is a hydrogen atom or a methyl group; p is a number from 0 to 60; X is a 9,9-fluorenediyl group; and m is a number from 0 to 10.)
[5] A display device comprising a protective film formed by curing the photosensitive resin composition according to [4] above.

The present invention provides a protective film that is heat-resistant, low-gassing, chemical-resistant, and developable, as well as being flexible and tough. For example, it can be used as a protective film for color filters and touch panels of flexible displays, and can also be used for display devices that require flexibility. Furthermore, it can be used in a wide range of applications as a component of various components such as optical members, optical device members, and electric and electronic parts that require properties such as transparency, heat resistance, flexibility, and toughness.

[Protective Film]
The protective film of the present invention is not particularly limited, but is preferably used as a protective film that protects the base of a panel such as a display or a wiring board in a display device such as a liquid crystal display device, an organic EL device, or a touch panel, and has high transparency and does not have an optical effect. In addition to this protective application, the film can also be used for applications such as protective coatings for the purpose of hard coatings on flexible films, plastic lenses, etc.

The protective film of the present invention has an elongation of 1.5% or more. Preferably, it is 2.0% or more. Because of such elongation characteristics, the protective film of the present invention is useful as a protective film that is a component of a color filter, a touch panel, etc., particularly in a flexible display. The elongation refers to the elongation measured by a tensile test, as exemplified in the examples described later, and is preferably measured by a method conforming to JIS K7161, for example. In addition, the thickness of the protective film varies depending on the application and the design of the structural member, but the protective film of the present invention can be used at a thickness of 0.1 to 100 μm. It is preferable that the protective film of the present invention has the above-mentioned elongation characteristics at least when converted into a thickness of 50 μm.

The protective film of the present invention is formed using a photosensitive resin composition described later, and in particular contains, as component (A), a specific epoxy (meth)acrylate compound (A-1) and/or an epoxy (meth)acrylate acid adduct (A-2) having a fluorene skeleton (hereinafter collectively referred to as "fluorene type resin (A)" or the like), and the fluorene type resin (A) is contained in an amount of 5 mass% or more in the solid content of the protective film. Preferably, the fluorene type resin (A) is contained in the protective film in an amount of 10 mass% or more. The upper limit of the fluorene type resin (A) is preferably 90 mass% or less, more preferably 80 mass% or less. By containing 5 mass% or more of these components in the protective film, the properties of the fluorene type resin (A), such as heat resistance, can be expressed.

Here, the above fluorene type resin (A) is produced as follows: That is, it is an epoxy (meth)acrylate compound (A-1) obtained by reacting an epoxy compound represented by the following general formula (1) having two glycidyl ether groups obtained by reacting a bisphenol with epichlorohydrin or the like with (meth)acrylic acid, a (meth)acrylic acid derivative represented by the following general formula (2), or a (meth)acrylic acid derivative represented by the following general formula (3), or it is an epoxy (meth)acrylate acid adduct (A-2) obtained by further reacting the obtained epoxy (meth)acrylate compound with a polyvalent carboxylic acid or its acid anhydride, and one or both of these compounds are included.

In the above general formula (1), R ₁ , R ₂ , R ₃ and R ₄ are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom or a phenyl group, preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a phenyl group, more preferably a hydrogen atom. X is a 9,9-fluorenediyl group, and m is a number from 0 to 10. Furthermore, in the general formulae (2) and (3), R ₅ is a divalent aliphatic or aromatic hydrocarbon group having 2 to 20 carbon atoms, R ₆ is a divalent alkylene group or alkylarylene group having 2 to 22 carbon atoms, and R ₇ is a hydrogen atom or a methyl group. p represents a number from 0 to 60.

ここで、Ｒ_１、Ｒ_２、Ｒ_３及びＲ_４、Ｘ、並びにｍは、上記の記述と同様である。Ｇは、（メタ）アクリル酸残基であるか、又は以下の一般式（２’）若しくは（３’）で表される置換基である。

The reaction of such an epoxy compound with (meth)acrylic acid or a (meth)acrylic acid derivative can be carried out by a known method, and for example, it is advantageous in terms of production to use about 2 moles of (meth)acrylic acid or a (meth)acrylic acid derivative per mole of the epoxy compound. The epoxy (meth)acrylate compound (A-1) obtained by this reaction is preferably represented by the following general formula (4).

Here, R ₁ , R ₂ , R ₃ and R ₄ , X, and m are the same as those described above. G is a (meth)acrylic acid residue or a substituent represented by the following general formula (2′) or (3′).

Preferred examples of bisphenols that give the epoxy compound of general formula (1) include 9,9-bis(4-hydroxyphenyl)fluorene having a 9,9-fluorenyl group, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(4-hydroxy-3-chlorophenyl)fluorene, 9,9-bis(4-hydroxy-3-bromophenyl)fluorene, 9,9-bis(4-hydroxy-3-fluorophenyl)fluorene, 9,9-bis(4-hydroxy-3,5-dimethylphenyl)fluorene, 9,9-bis(4-hydroxy-3,5-dichlorophenyl)fluorene, and 9,9-bis(4-hydroxy-3,5-dibromophenyl)fluorene.

The epoxy (meth)acrylate compound (A-1) of the fluorene-type resin (A) can be obtained from an epoxy compound derived from such a bisphenol. Here, there is no problem with the performance of the present invention as long as the average value of m in the general formula (1) is in the range of 0 to 10, preferably 0 to 2.

Next, among the compounds to be reacted with the epoxy compound of general formula (1), the (meth)acrylic acid derivatives represented by the above general formulas (2) and (3) and the substituents of general formulas (2') and (3') due to them will be described.
These have a polymerizable unsaturated group and at least one or more ester bonds, and first, _R6 represents an alkylene group or an alkylarylene group having 2 to 22 carbon atoms. The alkylene group may be either linear or branched, and examples thereof include ethylene, propylene, isopropylene, n-butylene, isobutylene, sec-butylene, t-butylene, pentylene, hexylene, heptylene, octylene, nonene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, nonadecylene, didecyl, henikosilene, and docosilene groups. The alkylarylene group may be an unsubstituted arylene group as long as it is within the range of the carbon number, and examples thereof include -Ph-Ph- (2,2'-biphenylene group), -Ph-Ph-Ph- (triphenylene group), -Ph-C( _CH3 ) ₂ -Ph- (residue such as bisphenol A) [Ph represents a phenylene group], o-, m-, or p-phenylene-substituted toluylene, cresylene, ethylphenylene, n-propylphenylene, isopropylphenylene, linear or branched butylphenylene, pentylphenylene, hexylphenylene, heptylphenyl, octylphenylene, nonylphenylene, decylphenylene, undecylphenylene, dodecylphenylene, tridecylphenylene, tetradecylphenylene, heptadecylphenylene, and hexadecylphenylene groups. Furthermore, the aforementioned alkylarylene group may be substituted di- to tetra-ally as long as the number of carbon atoms does not exceed the range, and the alkylene moiety may be interrupted by an unsaturated bond, an ether bond, an ester bond, an amide bond or a urethane bond.

Furthermore, _R5 represents an aliphatic or aromatic hydrocarbon group having 2 to 20 carbon atoms. For example, the aliphatic hydrocarbon group may be either linear or branched, and examples thereof include ethylene, propylene, isopropylene, n-butylene, isobutylene, sec-butylene, t-butylene, pentylene, hexylene, heptylene, octylene, nonene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, nonadecylene, and didecyl groups. The aromatic hydrocarbon group may be unsubstituted within the range of the carbon number, and examples thereof include -Ph-Ph- (2,2'-biphenylene group), -Ph-Ph-Ph- (triphenylene group), -Ph-C( _CH3 ) ₂ -Ph- (residues such as bisphenol A), o-, m-, or p-phenylene-substituted toluylene, cresylene, ethylphenylene, n-propylphenylene, isopropylphenylene, linear or branched butylphenylene, pentylphenylene, hexylphenylene, heptylphenylene, octylphenylene, nonylphenylene, decylphenylene, undecylphenylene, dodecylphenylene, tridecylphenylene, and tetradecylphenylene groups, but may be 2-4 substituted as long as the range of the carbon number is not exceeded, and the alkylene moiety may be interrupted by an unsaturated bond, an ether bond, an ester bond, an amide bond, or a urethane bond.

In addition, p represents a number between 0 and 60, but depending on the compound, there is concern that the distribution may be so wide that it may reduce the resin performance or may not provide sufficient hardening as a cured product, so a range of 0 to 40 is preferable, and 0 to 20 is even more preferable, as this will maintain the performance of the resin of the present invention.

As the polyvalent carboxylic acid or its anhydride to be reacted with the obtained epoxy (meth)acrylate compound (A-1), it is preferable to use a tetracarboxylic acid or its dianhydride (a), or a dicarboxylic acid or tricarboxylic acid or their monoanhydride (b), which can react with the hydroxyl group in the epoxy (meth)acrylate compound (A-1). These acid components are effective whether they are saturated or unsaturated.

Here, as the tetracarboxylic acid or its dianhydride (a), a chain-type hydrocarbon tetracarboxylic acid or its dianhydride, an alicyclic tetracarboxylic acid or its dianhydride, or an aromatic polyvalent carboxylic acid or its dianhydride is used. Examples of the chain-type hydrocarbon tetracarboxylic acid or its dianhydride include butane tetracarboxylic acid, pentane tetracarboxylic acid, hexane tetracarboxylic acid, etc., and may further include a chain-type hydrocarbon tetracarboxylic acid or its dianhydride having an arbitrary substituent introduced therein. Examples of the alicyclic tetracarboxylic acid or its dianhydride include cyclobutane tetracarboxylic acid, cyclopentane tetracarboxylic acid, cyclohexane tetracarboxylic acid, cycloheptane tetracarboxylic acid, norbornane tetracarboxylic acid, etc., and may further include an alicyclic tetracarboxylic acid or its dianhydride having an arbitrary substituent introduced therein. Examples of the aromatic tetracarboxylic acid or its dianhydride include pyromellitic acid, benzophenone tetracarboxylic acid, biphenyl tetracarboxylic acid, biphenyl ether tetracarboxylic acid, or its dianhydride, and may further include an aromatic tetracarboxylic acid or its dianhydride having an arbitrary substituent introduced therein. Two or more of these tetracarboxylic acids or their dianhydrides (a) can also be used in combination.

As the dicarboxylic acid, tricarboxylic acid or their monoanhydrides (b), chain hydrocarbon dicarboxylic acid or tricarboxylic acid or their monoanhydrides, alicyclic dicarboxylic acid or tricarboxylic acid or their monoanhydrides, or aromatic dicarboxylic acid or tricarboxylic acid or their monoanhydrides are used. Examples of the chain hydrocarbon dicarboxylic acid or tricarboxylic acid or their monoanhydrides include succinic acid, acetylsuccinic acid, maleic acid, adipic acid, itaconic acid, azelaic acid, citramalic acid, malonic acid, glutaric acid, citric acid, tartaric acid, oxoglutaric acid, pimelic acid, sebacic acid, suberic acid, and diglycolic acid, and may further include chain hydrocarbon dicarboxylic acid or tricarboxylic acid or their monoanhydrides having any substituent introduced therein. In addition, the alicyclic dicarboxylic acid or tricarboxylic acid or its monoanhydride may be, for example, a compound such as cyclobutanedicarboxylic acid, cyclopentanedicarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, or norbornanedicarboxylic acid, and may further be an alicyclic dicarboxylic acid or tricarboxylic acid or its monoanhydride having an arbitrary substituent introduced therein. In addition, the aromatic dicarboxylic acid or tricarboxylic acid or its monoanhydride may be, for example, a compound such as phthalic acid, isophthalic acid, or trimellitic acid, and may further be an aromatic dicarboxylic acid or tricarboxylic acid or its monoanhydride having an arbitrary substituent introduced therein. These dicarboxylic acids or tricarboxylic acids or their monoanhydrides (b) may be used in combination of two or more kinds.

The method of reacting such an epoxy (meth)acrylate compound (A-1) with a polyvalent carboxylic acid or its acid anhydride is not particularly limited, and for example, a known method can be adopted in which the reaction is carried out at a reaction temperature of 90 to 140°C. It is preferable to quantitatively react the epoxy (meth)acrylate compound (A-1), tetracarboxylic acid or its acid dianhydride (a), dicarboxylic acid or tricarboxylic acid or its acid monoanhydride (b) so that the terminal of the compound is a carboxylic acid group, and the molar ratio of (A-1):(a):(b) is 1:0.1 to 0.5:0.001 to 1.0. It is more preferable to quantitatively react (A-1)/[(a)+(b)]=1 to 5, (a)/(b)=1 to 40. By making (I)/[(a)+(b)] 1 or more, the terminals of the epoxy (meth)acrylate compound do not become acid anhydrides, and unreacted acid anhydrides do not remain and become foreign matter, so that the resin can exhibit the expected performance. In addition, by making (A-1)/[(a)+(b)] 5 or less, the stability over time is not reduced by unreacted epoxy (meth)acrylate compound (A-1). In addition, by making (a)/(b) = 1 to 40, the molecular weight of the resin can be set in an appropriate range. Here, it is preferable that the reaction temperature is 90 to 130°C to uniformly dissolve the charged raw materials and react, and then react and mature at 40 to 80°C.

（ここで、Ｗは下記一般式（１’）で表されるビスフェノール類誘導体を示し、Ｙは４価のカルボン酸残基を示す。Ｇは（メタ）アクリル酸残基であるか又は上記一般式（２’）若しくは（３’）で表される置換基を示し、Ｚは水素原子または一般式（６）で表される置換基である。ｎは１～２０の数を表す。）

（ここで、Ｒ_１、Ｒ_２、Ｒ_３及びＲ_４、Ｘ、並びにｍは、上記の記述と同様である。）

（ここで、Ｌは２又は３価のカルボン酸残基、ｑは１又は２である。） The epoxy (meth)acrylate acid adduct (A-2) obtained by reacting the epoxy (meth)acrylate compound (A-1) with a polyvalent carboxylic acid or an acid anhydride thereof can be preferably represented by the following general formula (5).

(W represents a bisphenol derivative represented by the following general formula (1'), Y represents a tetravalent carboxylic acid residue, G represents a (meth)acrylic acid residue or a substituent represented by the above general formula (2') or (3'), Z is a hydrogen atom or a substituent represented by the general formula (6), and n represents a number from 1 to 20.)

(wherein R ₁ , R ₂ , R ₃ and R ₄ , X, and m are as defined above.)

(wherein L is a di- or tri-carboxylic acid residue, and q is 1 or 2.)

In addition, the number average molecular weight of the resulting epoxy (meth)acrylate compound (A-1) or epoxy (meth)acrylate acid adduct (A-2) in terms of polystyrene, as measured by gel permeation chromatography (GPC), is preferably 1000 or more. If the molecular weight is smaller than this, film formation cannot be performed properly, the alkali resistance of the photosensitive resin composition using (A-2) is insufficient, the pattern is chipped by alkaline development following photocuring, and the reproducibility of the fine line pattern is significantly reduced. Furthermore, the weight average molecular weight (Mw) is preferably in the range of 2000 to 50,000, and more preferably between 2000 and 7000. If the weight average molecular weight (Mw) is less than 2000, film formation cannot be performed properly, the adhesion of the pattern during development of the photosensitive resin composition using (A-2) cannot be maintained, and pattern peeling occurs, and if the weight average molecular weight (Mw) exceeds 50,000, the remaining film in the unexposed area is likely to remain during development. Furthermore, it is desirable for the acid value of (A-2) to be in the range of 30 to 200 mgKOH/g. If this value is less than 30 mgKOH/g, the alkaline development of the photosensitive resin composition using these compounds will not go well, or special development conditions such as strong alkali will be required, while if it exceeds 200 mgKOH/g, the penetration of the alkaline developer into the photosensitive resin composition using these compounds will be too rapid, causing peeling development, so neither is preferable. Note that the (A-1) and (A-2) components can be used alone or in a mixture of two or more.

In addition to the above-mentioned fluorene-type resin (A), the protective film of the present invention preferably contains a photopolymerizable monomer (B) having two polymerizable unsaturated groups (hereinafter simply referred to as "photopolymerizable monomer (B)"). More preferably, the photopolymerizable monomer (B) has an aromatic group or an alicyclic hydrocarbon group. In this case, the content of the photopolymerizable monomer (B) in the solid content is preferably 10% by mass or more. By containing a predetermined amount of such photopolymerizable monomer (B), it is preferable that the elongation of the protective film can be improved. In this case, the elongation is preferably 2.0% or more.

Examples of such photopolymerizable monomers (B) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, tetramethylene glycol di(meth)acrylate, glycerol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,5-pentanediol di(meth)acrylate. Examples of the di(meth)acrylate include 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, di(meth)acrylate of neopentyl glycol ethylene oxide adduct, di(meth)acrylate of neopentyl glycol propylene oxide adduct, di(meth)acrylate of ethylene oxide adduct of bisphenol A, di(meth)acrylate of propylene oxide adduct of bisphenol A, di(meth)acrylate of ethylene oxide adduct of hydrogenated bisphenol A, di(meth)acrylate of propylene oxide adduct of hydrogenated bisphenol A, tricyclo[5.2.1.0 ^2,6 ]decanedimethanol di(meth)acrylate, 1,3-adamantanediol di(meth)acrylate, 1,3,5-adamantanetriol di(meth)acrylate, etc. Among these, compounds having an aromatic group or an alicyclic group can be preferably used.
Depending on the properties required for the protective film, a polyfunctional monomer having a total of three or more groups selected from the group consisting of acryloyl groups and/or methacryloyl groups can be added in addition to the photopolymerizable monomer (B). For example, (meth)acrylic acid esters such as trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, glycerol tri(meth)acrylate, sorbitol penta(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, 1,3,5-adamantanetriol tri(meth)acrylate, alkylene oxide-modified hexa(meth)acrylate of phosphazene, and caprolactone-modified dipentaerythritol hexa(meth)acrylate, and dendritic polymers having a (meth)acrylic group as a compound having an ethylenic double bond are included. These polyfunctional monomers may be used alone or in combination of two or more thereof. Note that the component (B) and the polyfunctional monomer do not have a free carboxy group.

An example of a dendritic polymer having a (meth)acrylic group as a compound having an ethylenic double bond is a dendritic polymer obtained by adding a polyvalent mercapto compound to a part of the carbon-carbon double bond in the (meth)acrylate group of a polyfunctional (meth)acrylate compound. Specifically, it includes a dendritic polymer obtained by reacting the (meth)acrylate of a polyfunctional (meth)acrylate compound of general formula (7) with a polyvalent mercapto compound of general formula (8).

Here, R ₁₀ represents a hydrogen atom or a methyl group, R ₁₁ represents the remaining portion of R ₈ (OH) _s where one of the s hydroxyl groups is donated to the ester bond in the formula, and preferred R ₈ (OH) _s is a polyhydric alcohol based on a non-aromatic linear or branched hydrocarbon skeleton having 2 to 8 carbon atoms, a polyhydric alcohol ether formed by linking multiple molecules of the polyhydric alcohol via ether bonds by dehydration condensation of the alcohol, or an ester of such a polyhydric alcohol or polyhydric alcohol ether with a hydroxy acid. s and t independently represent integers of 2 to 20, provided that s is greater than or equal to t.

Here, R ₉ is a single bond or a divalent to hexavalent C1 to C6 hydrocarbon group, r is 2 when R ₉ is a single bond, and r is an integer from 2 to 6 when R ₉ is a divalent to hexavalent group.

Specific examples of polyfunctional (meth)acrylate compounds represented by general formula (7) include (meth)acrylic acid esters such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide modified trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone modified pentaerythritol tri(meth)acrylate. These compounds may be used alone or in combination of two or more.

Specific examples of polyvalent mercapto compounds represented by general formula (8) include trimethylolpropane tri(mercaptoacetate), trimethylolpropane tri(mercaptopropionate), pentaerythritol tetra(mercaptoacetate), pentaerythritol tri(mercaptoacetate), pentaerythritol tetra(mercaptopropionate), dipentaerythritol hexa(mercaptoacetate), dipentaerythritol hexa(mercaptopropionate), etc. These compounds may be used alone or in combination of two or more.

In the protective film of the present invention, the blending ratio of the above-mentioned (A) and (B) components [(A)/(B)] is preferably 100/0 to 5/95. If the blending ratio of the (A) component is low, the cured product after the photocuring reaction becomes brittle, and when developed, the acid value of the coating film in the unexposed areas is low, so that the solubility in an alkaline developer decreases, resulting in problems such as the pattern edges becoming loose and not sharp. Conversely, if the blending ratio of the (A) component is higher than the above range, the proportion of photoreactive functional groups in the photoreactive components ((A) component + (B) component) is low, and the formation of a crosslinked structure by the photocuring reaction may be insufficient.

The protective film of the present invention is preferably produced from a photosensitive resin composition having the following components and contents:
(A) 10 to 88% by mass of the above fluorene type resin,
(B) 10 to 88% by mass of the above-mentioned photopolymerizable monomer, and (C) 1 to 60 parts by mass of a photopolymerization initiator per 100 parts by mass of the total amount of the (A) component and the (B) component.

(C) Examples of photopolymerization initiators include acetophenones such as acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, dichloroacetophenone, trichloroacetophenone, and p-tert-butylacetophenone; benzophenones such as benzophenone, 2-chlorobenzophenone, and p,p'-bisdimethylaminobenzophenone; benzoin ethers such as benzyl, benzoin, benzoin methyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; α-aminoalkylphenones such as 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1; 2-(o-chlorophenyl)-4,5-phenylbiimidazole, 2-(o-chlorophenyl)-4,5-phenylbiimidazole, biimidazole compounds such as 2-(o-chlorophenyl)-4,5-diphenylbiimidazole, 2-(o-methoxyphenyl)-4,5-diphenylbiimidazole, 2-(o-methoxyphenyl)-4,5-diphenylbiimidazole, and 2,4,5-triarylbiimidazole; 2-trichloromethyl-5-styryl-1,3,4-oxadiazole, 2-trichloromethyl-5-(p-cyanostyryl)-1,3, halomethylthiazole compounds such as 4-oxadiazole and 2-trichloromethyl-5-(p-methoxystyryl)-1,3,4-oxadiazole; 2,4,6-tris(trichloromethyl)-1,3,5-triazine, 2-methyl-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-phenyl-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-chlorophenyl)-4,6-bis (trichloromethyl)-1,3,5-triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(3,4,5-trimethoxystyryl)-4,6-bis(trichloromethyl) halomethyl-S-triazine compounds such as 2-(4-methylthiostyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine; 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime), 1-(4-phenylsulfanylphenyl)butane-1,2-dione-2-oxime-O-benzoate, 1-(4-methylsulfanylphenyl)butane-1,2-dione-2-oxime-O-benzoate, 1-(4-methylsulfanylphenyl)butane-1,2-dione-2-oxime-O-benzoate, O-acyloxime compounds such as 1-(4-methylsulfanylphenyl)butane-1-one oxime-O-acetate and 1-(4-methylsulfanylphenyl)butan-1-one oxime-O-acetate; sulfur compounds such as benzyl dimethyl ketal, thioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2-methylthioxanthone, and 2-isopropylthioxanthone; anthraquinones such as 2-ethylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, and 2,3-diphenylanthraquinone; organic peroxides such as azobisisobutylnitrile, benzoyl peroxide, and cumene peroxide, thiol compounds such as 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, and 2-mercaptobenzothiazole; and tertiary amines such as triethanolamine and triethylamine. These photopolymerization initiators may be used alone or in combination of two or more. The photopolymerization initiator of the present invention contains a sensitizer.

[Other ingredients]
The photosensitive resin composition for obtaining the protective film of the present invention may contain other optional components as necessary. For example, epoxy compounds (including epoxy resins), fillers, resins other than component A, dendritic polymers and epoxy resins, additives, etc. may be contained. Here, examples of fillers include silica, titania, zirconia, etc., examples of other resins include vinyl resins, polyester resins, polyamide resins, polyimide resins, polyurethane resins, polyether resins, melamine resins, etc., and examples of additives include dispersants, surfactants, silane coupling agents, viscosity modifiers, wetting agents, defoamers, polymerization inhibitors and antioxidants, ultraviolet absorbers, thermal radical initiators, etc. As these optional components, known compounds can be used without any particular restrictions.

Examples of coupling agents that can be used include silane coupling agents (such as 3-(glycidyloxy)propyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-ureidopropyltriethoxysilane), titanium-based coupling agents, and aluminum-based coupling agents. Examples of thermal radical initiators include azo-based initiators such as 2,2-azobisisobutyronitrile, dimethyl 2,2-azobis 2-methylpropionate, and 1,1'-azobis(1-acetoxy-1-phenylethane), and peroxides such as benzoyl peroxide.

In addition, surfactants (fluorine-based surfactants, silicone-based surfactants, etc.) may be used. As the surfactant, known surfactants such as silicone-based and fluorine-based surfactants can be used without any particular limitation. Examples of silicone-based surfactants include side chain modified polydimethylsiloxane, both end modified polydimethylsiloxane, one end modified polydimethylsiloxane, side chain both end modified polydimethylsiloxane, etc. Examples of fluorine-based surfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chains. In addition, only one of these surfactants may be used alone, or two or more of them may be used in combination. Surfactants are used, for example, to adjust the surface tension when a solution of a photosensitive resin composition is applied, and the amount added ranges from 0.001 to 0.1% by mass in the photosensitive resin composition. The amount added varies depending on the type of surfactant, and is usually in the range of 0.001 to 0.01% by mass for silicone-based surfactants and 0.01 to 0.1% by mass for fluorine-based surfactants.

In addition, known compounds can be used as the solvent. For example, ester-based solvents (butyl acetate, cyclohexyl acetate, etc.), ketone-based solvents (methyl isobutyl ketone, cyclohexanone, etc.), ether-based solvents (diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, etc.), alcohol-based solvents (3-methoxybutanol, ethylene glycol mono-t-butyl ether, etc.), aromatic solvents (toluene, xylene, etc.), aliphatic solvents, amine-based solvents, and amide-based solvents can be used without particular restrictions. From the viewpoint of safety, ester-based and ether-based solvents having a propylene glycol skeleton, such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol diacetate are preferred. Also preferred are 3-methoxybutyl acetate, 3-methoxy-3-methylbutyl acetate, and 1,3-butylene glycol diacetate, which have a similar structure.

Epoxy compounds can be used when it is desired to improve the functions of the protective film, such as chemical resistance. Examples of epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol fluorene type epoxy compounds, phenol novolac type epoxy compounds, cresol novolac type epoxy compounds, phenol aralkyl type epoxy compounds, phenol novolac compounds containing a naphthalene skeleton (e.g., "NC-7000L" manufactured by Nippon Kayaku Co., Ltd.), naphthol aralkyl type epoxy compounds, trisphenol methane type epoxy compounds, tetrakisphenol ethane type epoxy compounds, glycidyl ethers of polyhydric alcohols, glycidyl esters of polycarboxylic acids, and copolymers of methacrylic acid and glycidyl methacrylate (methacrylic acid copolymers). ) copolymers of monomers having a (meth)acrylic group containing glycidyl acrylate as a unit, alicyclic epoxy compounds represented by 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, polyfunctional epoxy compounds having a dicyclopentadiene skeleton (e.g., "HP-7200 series" manufactured by DIC Corporation), 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (e.g., "EHPE3150" manufactured by Daicel Corporation), epoxidized polybutadiene (e.g., "NISSO-PB.JP-100" manufactured by Nippon Soda Co., Ltd.), epoxy compounds having a silicone skeleton, and the like. The epoxy compounds may be used alone or in combination of two or more kinds.
In addition, when an epoxy compound is blended, a curing agent for the epoxy compound selected from the group consisting of polycarboxylic acids, anhydrides of polycarboxylic acids, and thermally decomposable esters of polycarboxylic acids, or a known compound for promoting curing known as a curing accelerator, curing catalyst, or latent curing agent for the epoxy compound can be used as necessary.

In addition, there is no particular restriction on the solid content concentration of the solution when the photosensitive resin composition of the present invention is used for coating and forming a film. For example, for use as a protective film for a color filter, the solid content concentration, which is the total amount of components other than the solvent, is generally adjusted to a range of 10 to 30 mass%. In addition, in order to improve the flatness of the protective film for the color filter, it is preferable to control the drying property of the photosensitive resin composition by using 40 to 90 mass% of a solvent having a boiling point of less than 150°C at normal pressure and 10 to 60 mass% of a solvent having a boiling point of 150°C or more at normal pressure in combination. In addition, it is desirable that the solid content excluding the solvent (solid content includes monomers that become solid content after curing) contains a total of 80 mass% of components (A) to (C), preferably 90 mass% or more. The amount of solvent varies depending on the target viscosity, but it is preferable that the amount of solvent is in the range of 70 to 90 mass% in the photosensitive resin composition.

The protective film in the present invention can be formed by curing the above-mentioned photosensitive resin composition by the following photolithography method. First, the photosensitive resin composition is applied onto a glass substrate, a plastic substrate, or a substrate on which a pixel pattern of a color filter or an electrode pattern for pixel driving of a TFT or the like is formed, and then the solvent is dried (prebaked). After that, a photomask is placed on the film thus obtained, and the exposed parts are cured by irradiating with ultraviolet light. Development is then performed using an alkaline aqueous solution to dissolve the unexposed parts to form a pattern, and post-baking (thermal firing) is further performed as a post-curing method.

Examples of transparent substrates onto which the solution of the photosensitive resin composition is applied include glass substrates and transparent films (e.g., polycarbonate, polyethylene terephthalate, polyethersulfone, etc.) on which transparent electrodes such as ITO or gold are vapor-deposited or patterned. As a method for applying the solution of the photosensitive resin composition, any method such as the well-known solution immersion method, spray method, and methods using a roller coater, land coater, or spinner machine can be used. After applying the solution to the desired thickness by these methods, the solvent is removed (prebaking) to form a film. Prebaking is performed by heating in an oven, hot plate, etc. The heating temperature and heating time in prebaking are appropriately selected depending on the solvent used, and are performed for example at a temperature of 60 to 110°C for 1 to 5 minutes.

The exposure performed after pre-baking is performed using an ultraviolet exposure device, and only the resist in the area corresponding to the pattern is exposed by exposing through a photomask. The exposure device and its exposure irradiation conditions are appropriately selected, and exposure is performed using a light source such as an ultra-high pressure mercury lamp, high pressure mercury lamp, metal halide lamp, or far ultraviolet lamp, to photocure the photosensitive resin composition in the coating film.

After exposure, alkaline development is carried out in order to remove the unexposed portions of the resist, and the desired pattern is formed by this development. Examples of developers suitable for this alkaline development include aqueous solutions of carbonates of alkali metals or alkaline earth metals, and aqueous solutions of hydroxides of alkali metals. In particular, it is preferable to use a weakly alkaline aqueous solution containing 0.05 to 3 mass % of carbonates such as sodium carbonate, potassium carbonate, or lithium carbonate at a temperature of 23 to 28°C, and fine images can be precisely formed using a commercially available developing machine or ultrasonic cleaner.

After development, a heat treatment (post-baking) is preferably performed at a temperature of 80 to 250°C (set so as not to exceed the heat resistance temperature of the substrate) for 20 to 90 minutes. This post-baking is performed for the purpose of increasing the adhesion between the patterned resin film and the substrate. As with the pre-baking, this is performed by heating in an oven, hot plate, or the like. More preferred ranges for the heat treatment conditions for post-baking are a temperature of 180 to 230°C and a heating time of 30 to 60 minutes. The patterned resin film of the present invention is formed through each of the steps of the photolithography method described above.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these. We will start with a preparation example of the photosensitive resin composition of the present invention, and then explain the evaluation results of the coating film formed using the photosensitive resin composition.

First, a synthesis example of the fluorene-based resin (A) will be described. The resin in the synthesis example was evaluated as follows.
[Solid content]
1 g of the resin solution obtained in Synthesis Example was impregnated into a glass filter (weight: _W0 (g)), weighed [ _W1 (g)], and the weight after heating at 160°C for 2 hours [ _W2 (g)] was calculated from the following formula.
Solid content concentration (wt%) = 100 x (W ₂ - W ₀ )/(W ₁ - W ₀ )

[Acid value]
The resin solution was dissolved in dioxane and titrated with a 1/10N KOH aqueous solution using a potentiometric titrator (manufactured by Hiranuma Sangyo Co., Ltd., product name COM-1600) to determine the content.

[Molecular weight]
Measurement was performed using gel permeation chromatography (GPC) [manufactured by Tosoh Corporation, product name: HLC-8220GPC, solvent: tetrahydrofuran, columns: TSKgelSuperH-2000 (2 columns) + TSKgelSuperH-3000 (1 column) + TSKgelSuperH-4000 (1 column) + TSKgelSuper-H5000 (1 column) [manufactured by Tosoh Corporation], temperature: 40° C., rate: 0.6 ml/min], and the weight average molecular weight (Mw) was calculated as a value converted into a standard polystyrene [PS-oligomer kit manufactured by Tosoh Corporation].

The abbreviations used in the synthesis examples are as follows.
BPFE: Bisphenol fluorene type epoxy compound [a reaction product of 9,9-bis(4-hydroxyphenyl)fluorene and chloromethyloxirane. Epoxy equivalent: 250 g/eq]
AA: Acrylic acid PGMEA: Propylene glycol monomethyl ether acetate TEAB: Tetraethylammonium bromide BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride THPA: Tetrahydrophthalic anhydride MAA: Methacrylic acid MMA: Methyl methacrylate CHMA: Cyclohexyl methacrylate AIBN: Azobisisobutyronitrile GMA: Glycidyl methacrylate TPP: Triphenylphosphine TBPC: 2,6-di-tert-butyl-p-cresol

<Synthesis of fluorene-type resin (A)>
[Synthesis Example 1]
114.4g (0.23 mol) of BPFE, 33.2g (0.46 mol) of AA, 157g of PGMEA and 0.48g of TEAB were charged into a 500ml four-neck flask equipped with a reflux condenser, and the mixture was stirred for 20 hours under heating at 100 to 105 ° C. to react. Next, 35.3g (0.12 mol) of BPDA and 18.3g (0.12 mol) of THPA were charged into the flask and stirred for 6 hours at 120 to 125 ° C. to obtain a fluorene-type resin (A1). The solid content concentration of the obtained resin solution was 56.1% by mass, the acid value (solid content equivalent) was 103 mgKOH/g, and the Mw by GPC analysis was 3600.

[Synthesis Example 2]
In a 1 L four-neck flask equipped with a reflux condenser, 219.9 g (0.45 mol) of BPFE, 64.9 g (0.9 mol) of AA, 0.45 g of TPP, and 294 g of PGMEA were charged and stirred for 12 hours under heating at 100 to 105° C. to obtain a reaction product.
Next, 94.15 g (0.32 mol) of BPDA and 3.04 g (0.02 mol) of THPA were added to the reaction product and stirred for 6 hours under heating at 115 to 120° C. to obtain a fluorene-type resin (A2). The solid content of the resulting resin solution was 56.5% by mass, the acid value (solid content equivalent) was 97 mgKOH/g, and the Mw by GPC analysis was 5,500.

<Synthesis of Acrylic Polymer>
[Synthesis Example 3]
The acrylic polymer used in the comparative examples described below was synthesized according to the following procedure.
In a 1000 ml four-neck flask equipped with a nitrogen inlet tube and a reflux condenser, 51.65 g (0.60 mol) of MAA, 36.04 g (0.36 mol) of MMA, 40.38 g (0.24 mol) of CHMA, 5.91 g of AIBN, and 360 g of PGMEA were charged, and the mixture was polymerized by stirring for 8 hours under a nitrogen stream at 80 to 85 ° C. Further, 61.41 g (0.43 mol) of GMA, 2.27 g of TPP, and 0.086 g of TBPC were charged in the flask, and the mixture was stirred for 16 hours at 80 to 85 ° C. to obtain a resin solution. The solid content concentration of the obtained resin solution was 35.7 mass%, the acid value (solid content equivalent) was 50 mg KOH / g, and the Mw by GPC analysis was 19600.

(Preparation of Photosensitive Resin Composition)
The components were mixed according to the composition shown in Table 1, and the solid components were dissolved in the solvent by stirring and mixing at room temperature for 3 hours to prepare photosensitive resin compositions. The numerical values of the compositions are parts by mass.

The components used in the photosensitive resin compositions of the Examples , Reference Examples and Comparative Examples are shown below.
<(A) Fluorene-type resin>
A1: Resin obtained in Synthesis Example 1 A2: Resin obtained in Synthesis Example 2 <Acrylic polymer>
Resin obtained in Synthesis Example 3
<(B) Photopolymerizable Monomer>
B1: EO (ethylene oxide) modified bisphenol A di(meth)acrylate (manufactured by Kyoeisha Chemical Co., Ltd., product name: Light Acrylate BP-4EAL)
B2: Tricyclo[ ^5.2.1.02,6 ]decane dimethanol diacrylate (manufactured by Kyoeisha Chemical, product name: Light Acrylate DCP-A)
<Polyfunctional Monomer>
Mixture of dipentaerythritol pentaacrylate and hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., product name: KAYARAD DPHA)
<(C) Photopolymerization initiator>
Ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(0-acetyloxime) (BASF Japan, product name Irgacure OXE02)
<Coupling Agent>
KBE-585: 3-ureidopropyltrialkoxysilane <surfactant>
SH3775M: Polyether modified silicone (manufactured by The Dow Chemical Company)
<Solvent>
PGMEA: Propylene glycol monomethyl ether acetate DMDG: Diethylene glycol dimethyl ether EDM: Diethylene glycol ethyl methyl ether

The evaluation was carried out as follows.
[Elastic modulus (Young's modulus) and elongation]
Each photosensitive resin composition in Table 1 was applied to an alkali-free glass substrate (thickness 0.7 mm) using a spin coater, and dried on a hot plate at 90 ° C for 2 minutes to prepare a test piece. At this time, the application conditions (spin rotation speed) were adjusted so that a cured film with a film thickness of 50 μm was obtained. Next, an ultra-high pressure mercury lamp with an i-line illuminance of 30 mW / cm ² was irradiated with ultraviolet light of 50 mJ / cm ² to perform a photocuring reaction. Thereafter, the test piece was baked in a hot air oven at 230 ° C for 30 minutes, and peeled off from the alkali-free glass substrate to obtain a cured film. Using this cured film 8 mm × 80 mm as a sample, a tensile test was performed at a tensile speed of 10 mm / min using a Tensilon universal testing machine (manufactured by A & D, product name MCT-2150), and the elastic modulus (Young's modulus) (MPa) and tensile elongation (%) were obtained. The results are shown in Table 2 below.

(Flexibility)
Each photosensitive resin composition in Table 1 was applied to Kapton 100H (manufactured by Toray DuPont Co., Ltd., thickness 25 μm) using a spin coater, and dried on a hot plate at 90 ° C for 2 minutes to prepare a test piece. At this time, the coating conditions (spin rotation speed) were adjusted so that a cured film with a film thickness of 10 μm was obtained. Next, a photocuring reaction was performed by irradiating ultraviolet rays of 50 mJ / cm ² from an ultra-high pressure mercury lamp with an i-line illuminance of 30 mW / cm ^2. Thereafter, the test piece was baked in a hot air oven at 230 ° C for 30 minutes to obtain a cured film. This cured film 8 mm × 80 mm was used as a sample, and the Kapton 100H side of the sample was wrapped around a SUS cylinder with a diameter of 3 mm Φ until the bending angle became 180 degrees (U-shaped), and the occurrence of cracks in the coating film was visually observed.
○: No cracks occurred △: Cracks occurred ×: Cracks (large cracks) occurred during winding

(Hygroscopicity)
A sample of 8 mm x 80 mm was prepared in the same manner as in the evaluation of the elastic modulus. Next, this sample was left to stand for 24 hours in a constant temperature chamber device (Espec environmental tester SH-221) at 85 ° C. and 85% RH for moisture absorption. Then, 10 mg of this cured film was scraped off and sampled, and the weight loss amount when this was heated from room temperature to 150 ° C. at 10 ° C./min in a nitrogen atmosphere and held at 150 ° C. for 20 minutes was measured as the weight change due to moisture absorption of the film using a thermogravimetric analyzer (product name: Rigaku Corporation differential thermobalance Thermo plus EVO2), and three-level evaluation was performed according to the following criteria.
◎: Weight loss is less than 0.5%. ○: Weight loss is 0.5% or more and less than 2%. △: Weight loss is 2% or more and less than 3%. ×: Weight loss is 3% or more.

(Gas generation)
A cured film was prepared in the same manner as in the evaluation of the elastic modulus. 10 mg of the cured film was scraped off to obtain a sample, which was heated from room temperature to 120° C. at a rate of 10° C./min under air flow, held at 120° C. for 30 minutes, and then heated from 120° C. to 230° C. at a rate of 10° C./min and held at 230° C. for 3 hours. The weight loss was measured using a thermogravimetric analyzer (product name: Thermo plus EVO2, differential thermobalance, manufactured by Rigaku Corporation), and evaluated in three stages according to the following criteria.
◎: Weight loss is less than 5%. ○: Weight loss is 5% or more but less than 7%. △: Weight loss is 7% or more but less than 10%. ×: Weight loss is 10% or more.

Claims (6)

A protective film characterized in that it contains, in its solid content, 9.78 to 88.06 mass % of the following (A-1) and/or (A-2) and 9.78 to 88.06 mass % of a photopolymerizable monomer having two polymerizable unsaturated groups , and has an elongation of 2.0 % or more.
[Here, (A-1) is an epoxy (meth)acrylate compound obtained by reacting an epoxy compound represented by the following general formula (1) with (meth)acrylic acid, a compound represented by the following general formula (2) or a compound represented by the following general formula (3), and (A-2) is an epoxy (meth)acrylate acid adduct obtained by further reacting the epoxy (meth)acrylate compound with a polyvalent carboxylic acid or its acid anhydride.]

(wherein R ₁ , R ₂ , R ₃ and R ₄ are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom or a phenyl group; R ₅ is a divalent aliphatic or aromatic hydrocarbon group having 2 to 20 carbon atoms; R ₆ is a divalent alkylene group or alkylarylene group having 2 to 22 carbon atoms; R ₇ is a hydrogen atom or a methyl group; p is a number from 0 to 60; X is a 9,9-fluorenediyl group; and m is a number from 0 to 10.) The protective film according to claim 1, characterized in that the film thickness is 0.1 to 100 μm. 3. The protective film according to claim 1, which does not contain a polyfunctional monomer having a total of three or more groups selected from the group consisting of acryloyl groups and/or methacryloyl groups. 4. The protective film according to claim 1, wherein the solid content of the protective film contains 25 mass % or more of the (A-1) and/or the (A-2). A photosensitive resin composition for forming a protective film having an elongation of 2.0 % or more , comprising:
(A) 9.78 to 88.06 mass % of the following (A-1) and/or (A-2) (wherein (A-1) is an epoxy (meth)acrylate compound obtained by reacting an epoxy compound represented by the following general formula (1) with (meth)acrylic acid, a compound represented by the following general formula (2) or a compound represented by the following general formula (3), and (A-2) is an epoxy (meth)acrylate acid adduct obtained by further reacting the epoxy (meth)acrylate compound with a polyvalent carboxylic acid or an acid anhydride thereof),
(B) 9.78 to 88.06 % by mass of a photopolymerizable monomer having two polymerizable unsaturated groups, and (C) a photopolymerization initiator;
A photosensitive resin composition comprising 1 to 60 parts by mass of component C relative to 100 parts by mass of the total amount of components A and B.

(wherein R ₁ , R ₂ , R ₃ and R ₄ are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom or a phenyl group; R ₅ is a divalent aliphatic or aromatic hydrocarbon group having 2 to 20 carbon atoms; R ₆ is a divalent alkylene group or alkylarylene group having 2 to 22 carbon atoms; R ₇ is a hydrogen atom or a methyl group; p is a number from 0 to 60; X is a 9,9-fluorenediyl group; and m is a number from 0 to 10.) A display device comprising a protective film formed by curing the photosensitive resin composition according to claim 5 .