WO2018169036A1 - Photosensitive resin composition - Google Patents

Abstract

Disclosed is a photosensitive resin composition which has rapid developability and good curability with respect to active energy rays, and which provides a cured product that exhibits excellent elastic modulus recovery ratio with respect to external forces. This resin composition contains: (A) a polymerizable (meth)acrylic polymer which contains, as constituent elements, a monomer unit (1) that has a branched side chain having 2 to 3 ends which are respectively terminated with radically polymerizable substituents, a monomer unit (2) that has a bifurcated side chain having an end which is terminated with a carboxyl group and another end which is terminated with a radically polymerizable substituent, and optionally a monomer unit (3) that has a side chain having one end which is terminated with a radically polymerizable substituent; (B) a polyfunctional (meth)acrylate monomer; and (C) a photopolymerization initiator.

Description

Photosensitive resin composition

The present invention relates to a (meth) acrylic resin composition, and more particularly to a photosensitive resin composition, and particularly to a photosensitive resin composition used for a photospacer or the like.

In a display device such as a liquid crystal display (LCD), a structural unit including a plurality of (meth) acryloyloxy groups and a carboxyl group are used as a cured film such as a spacer for maintaining a constant thickness of an insulating film, a protective film, and a liquid crystal layer. A curable resin composition containing a polymer having a structural unit and a basic compound is known (Patent Document 1).

In the manufacture of a liquid crystal display (LCD), it is required to highly control the thickness of the liquid crystal layer (gap between the front and rear alignment films) to be constant, and the success or failure is directly related to the quality of the image quality. For this reason, spacers are used, and in recent years, column-like photospacers (PS) have been formed on color filters and the like. Since the photospacer is formed by photolithography, a resist having good photosensitivity is necessary as a material for producing the photospacer. At the same time, from the viewpoint of the efficiency of the production process, it is required that rapid developability, that is, unnecessary portions can be removed quickly by a developer after exposure of the resist. Furthermore, when an external force is applied to the display screen with a finger or the like, the external force is concentrated especially on the columnar photospacer. It is important that the resist used provides a cured product with an excellent elastic recovery rate so that recovery is possible.

Japanese Unexamined Patent Publication No. 2016-16393

An object of the present invention is to provide a cured product having good photosensitivity (curability) to active energy rays, rapid developability after exposure, and an excellent elastic recovery rate against deformation caused by external force. An active energy ray-curable resin composition is provided.

As a result of research in line with the above-mentioned purpose, the present inventors have found that a monomer having a branched side chain having radically polymerizable substituents at a plurality of ends, and a carboxyl group and radically polymerizable at a plurality of ends. A polymerizable resin composition comprising a polymerizable resin comprising a monomer having a branched side chain provided with a substituent as a constituent unit, and a polyfunctional (meth) acrylate monomer, It was found that when this was photocured, it had excellent photosensitivity, showed rapid developability into an alkaline solution after exposure, and the resulting cured product had an excellent elastic recovery rate. The present invention has been completed based on the findings and further studies. That is, the present invention provides the following.

1. Monomer units (1) each having a branched side chain with 2 to 3 ends ending in radically polymerizable substituents, 2 having ends ending with carboxyl groups and ends ending with radically polymerizable substituents A monomer unit (2) with a branched side chain, or a monomer unit (3) with a side chain having one end ending with a radically polymerizable substituent, A photosensitive resin composition comprising a polymerizable (meth) acrylic polymer (A), a polyfunctional (meth) acrylate monomer (B), and a photopolymerization initiator (C).
2. In the polymerizable (meth) acrylic polymer (A), the radical polymerizable substituent in the monomer unit (1) is a hydrocarbon chain comprising 3 to 5 carbon atoms forming a part of a side chain ( L), and the radical polymerizable substituent in the monomer unit (2) is substituted on a hydrocarbon chain (M) comprising 3 to 5 carbon atoms forming a part of the side chain. In addition, the carboxyl group is bonded to the hydrocarbon chain (M) via a group —OC (O) —Z—, and the group —Z— forming a part of the group has a carbon number 2 to 7 saturated or unsaturated chain or cyclic hydrocarbon skeleton or benzene ring, and the radical polymerizable substituent in the monomer unit (3) is a side chain Substituted on a hydrocarbon chain comprising 3 to 5 carbon atoms forming a part of In it, the first resin composition of.
3. The resin according to 1 or 2 above, wherein two bonding positions of the group -Z- in the monomer unit (2) are present on two adjacent carbon atoms among the carbon atoms constituting the group. Composition.
4). 4. The resin composition according to any one of 1 to 3 above, wherein the radical polymerizable substituents are each independently a (meth) acryloyloxy group.
5). The monomer unit (1) is composed of a monomer unit (1a) having an acryloyloxy group as the radical polymerizable substituent and a monomer unit (1b) having a methacryloyloxy group as the radical polymerizable substituent. The resin composition according to any one of 1 to 4 above.
6). The molar ratio between the monomer units constituting the polymerizable (meth) acrylic polymer (A) is as follows: monomer unit (1): monomer unit (2): monomer unit (3) = 20 to 80: 5 to 50: The resin composition according to any one of 1 to 5, which is 0 to 30.
7). The polymerizable (meth) acrylic polymer (A) has the following general formula:

 

 

[In the formula, each R ₁ independently represents a hydrogen atom or a methyl group, and X ₁ , X ₂ , X ₃ and X ₄ each independently represent a substituent represented by the following general formula (1) Represents

 

 

(Wherein R ₂ represents a hydrogen atom or a methyl group, and “*-” represents a single bond),
R ₃ represents any of the substituents represented by the following structural formula,

 

 

l, m and n represent the molar ratio of each monomer unit in the form of a ratio l: m: n. ] The resin composition as described in any one of 1 to 5 above.
8). 8. The resin composition as described in 7 above, wherein in the polymerizable (meth) acrylic polymer (A), the ratio l: m: n = 20 to 80: 5 to 50: 0 to 30.
9. In the general formula of the polymerizable (meth) acrylic polymer (A), the following formula:

 

 

The monomer unit (1) represented by the formula (1) comprises a monomer unit (1a) in which both X ₁ and X ₂ are acryloyloxy groups, and a monomer unit (1b) in which both X ₁ and X ₂ are methacryloyloxy groups The resin composition as described in 7 or 8 above.
10. The polymerizable (meth) acrylic polymer (A) has the following formula:

 

 

 

 

 

 

The composition according to any one of the above 7 to 9, which is represented by any of the above:
11. The polyfunctional (meth) acrylate monomer (B) is dipentaerythritol hexaacrylate, dipentaerythritol polyacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, tritriol. 11. The resin composition according to any one of 1 to 10 above, which is selected from the group consisting of methylolpropane triacrylate, ethoxylated isocyanuric acid triacrylate, and ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate.

12 The polymerizable (meth) acrylic polymer (A) further comprises a monomer unit (4) different from any of the monomer units (1), (2), and (3). The resin composition according to any one of 5.

According to the present invention, a resin composition that cures with good reactivity to active energy rays (in the present invention, it is collectively referred to as “photosensitivity”) and has rapid developability with respect to an alkaline developer after exposure. You can get things. Further, the resin composition of the present invention can give a cured product exhibiting an excellent elastic recovery rate against deformation caused by an external force load.

In the present invention, “active energy rays” refer to ionizing radiation such as ultraviolet rays, electron rays, α rays, β rays, and γ rays. Among these, for example, ultraviolet rays are convenient for handling, and a high-pressure mercury lamp or an ultrahigh-pressure mercury lamp can be easily used for irradiation.

In the present invention, the term “(meth) acrylic” comprehensively means a compound based on acrylic acid and methacrylic acid without distinguishing both. The same applies to the term “(meth) acrylate”.

In the present invention, the polymerizable (meth) acrylic polymer (A) comprises monomer units (1) and (2), or further comprises monomer units (3), each of these monomer units being (meth) Acrylic monomer unit. In the present invention, when the structure of each monomer unit is referred to as “side chain”, it means a part constituting a side chain with respect to a main chain formed by addition polymerization of a (meth) acrylate moiety that they have in common.

The monomer unit (1) has branched side chains with 2-3 ends, each ending in a radically polymerizable substituent. These radically polymerizable substituents are preferably substituted on the hydrocarbon chain (L), respectively, and the hydrocarbon chain (L) is preferably bonded to the main chain of the polymer via the group —COO—. is doing. The number of carbon atoms constituting the hydrocarbon chain (L) is preferably 3 to 5, more preferably 3 or 4, and particularly preferably 3.

The monomer unit (2) has two branched side chains having a terminal end ending with a carboxyl group and a terminal end ending with a radical polymerizable substituent. Here, the radical polymerizable substituent is preferably substituted on the hydrocarbon chain (M), and the hydrocarbon chain (M) is preferably connected to the main chain of the polymer via the group —COO—. Is bound to. The number of carbon atoms constituting the hydrocarbon chain (M) is preferably 3 to 5, more preferably 3 or 4, and particularly preferably 3. On the other hand, the carboxyl group is substituted on the hydrocarbon chain (M) via the group —OC (O) —Z—. Here, the group -Z-, which forms part of the group, has 2 to 7 carbon atoms and comprises a saturated or unsaturated chain or cyclic hydrocarbon skeleton or benzene ring. In the group -Z-, it is more preferable that the two bonding positions exist on two carbon atoms adjacent to each other among the carbon atoms constituting the group. The monomer unit (2) preferably has a molecular weight of less than 1000.

The monomer unit (3) has a side chain with one end that ends with a radically polymerizable substituent. The radical polymerizable substituent is preferably substituted on the hydrocarbon chain (N), and the hydrocarbon chain (N) is preferably bonded to the main chain of the polymer via the group —COO—. ing. The number of carbon atoms constituting the hydrocarbon chain (N) is preferably 3 to 5, more preferably 3 or 4, and particularly preferably 3.

In the monomer units (1) to (3), the “radical polymerizable substituent” is preferably a (meth) acryloyloxy group. The monomer unit (1) comprises a monomer unit (1a) having an acryloyloxy group as the radical polymerizable substituent and a monomer unit (1b) having a methacryloyloxy group as the radical polymerizable substituent. May be.

The polymerizable (meth) acrylic polymer (A) can be composed of monomer units (1) and (2) without including the monomer unit (3). In that case, there is no clear limit on the molar ratio of the monomer unit (1) to the monomer unit (2) in the polymer, but it is generally preferable that the monomer unit (1): monomer unit (2) = 20 to 80: 5. -50, more preferably 50-70: 10-30.

When the polymerizable (meth) acrylic polymer (A) is composed of the monomer unit (3), there is no clear limit on the molar ratio of the monomer units (1) to (3). In general, monomer unit (1): monomer unit (2): monomer unit (3) = 20 to 80: 5 to 50: 0 to 30, more preferably 50 to 70:10 to 30: 0 to 10 It is.

Further, from the viewpoint of increasing the elastic recovery rate of the photospacer, the polymerizable (meth) acrylic polymer (A) preferably has a double bond equivalent of 100 to 270. Here, “double bond equivalent” means the number of grams of the resin composition relative to 1 mol of acryloyl groups. The “gram number of the resin composition” means the mass of the entire resin composition (excluding the solvent).

The polymerizable (meth) acrylic polymer (A) may further contain additional monomer units other than the monomer units (1) to (3) as long as the object of the present invention is not violated. Such additional monomer units can be used for the purpose of adjusting physical properties such as glass transition point (Tg) and hydrophobicity of the photosensitive resin composition of the present invention, if desired. When the additional monomer unit “monomer unit (4)” is included, the molar ratio of each monomer unit constituting the polymerizable (meth) acrylic polymer (A) is not clearly limited, but generally preferably the monomer Unit (1): Monomer unit (2): Monomer unit (3): Monomer unit (4) = 20 to 80: 5 to 50: 0 to 30: 0 to 40, more preferably 50 to 70:10 to 30: 0 to 10: 0 to 30.

Examples of the additional monomer unit include, but are not limited to, polymerizable (meth) acrylic monomers. Specific examples of polymerizable (meth) acrylic monomers include dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentanyl acrylate, benzyl acrylate, and nonylphenoxy polyethylene glycol acrylate. , Nonylphenoxypolyethylene glycol acrylate, nonanediol diacrylate, polypropylene glycol acrylate, 1,4-butanediol dimethacrylate, dicyclopentenyloxyethyl methacrylate, dicyclopentanyl methacrylate, pentamethylpiperidyl methacrylate, tetra Methyl piperidyl methacrylate, methoxypolyethylene glycol methacrylate, benzyl methacrylate, neopentyl glycol dimethacrylate, poly Chi glycol dimethacrylate, and the like, but not limited thereto.

The polymerizable (meth) acrylic polymer (A) is particularly preferably represented by the following general formula:

 

 

[In the formula, each R ₁ independently represents a hydrogen atom or a methyl group, and X ₁ , X ₂ , X ₃ and X ₄ each independently represent a substituent represented by the following general formula (1) Represents

 

 

(Wherein R ₂ represents a hydrogen atom or a methyl group, and “*-” represents a single bond),
R ₃ represents any of the substituents represented by the following structural formula,

 

 

L, m, and n represent the molar ratio of each monomer unit in the form of l: m: n. ] Is shown.

In the above, in the general formula of the polymerizable (meth) acrylic polymer (A), the following formula

 

 

The monomer unit (1) represented by the formula (1) comprises a monomer unit (1a) in which both X ₁ and X ₂ are acryloyloxy groups, and a monomer unit (1b) in which both X ₁ and X ₂ are methacryloyloxy groups. It may be.

In the above, preferably the ratio l: m: n = 20 to 80: 5 to 50: 0 to 30, more preferably 50 to 70:10 to 30: 0 to 10.

Examples of the polyfunctional (meth) acrylate monomer (B) that is one of the constituent elements of the active energy ray-curable resin composition of the present invention include dipentaerythritol hexaacrylate, dipentaerythritol polyacrylate, pentaerythritol tris. Acrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, trimethylolpropane triacrylate, ethoxylated isocyanuric acid triacrylate, and ε-caprolactone modified tris- (2-acryloxyethyl) isocyanurate For example, but not limited to. Of these, dipentaerythritol hexaacrylate is one of the particularly preferred ones. In the resin composition of the present invention, the polyfunctional (meth) acrylate monomer (B) is preferably 50 to 350 parts by weight with respect to 100 parts by weight of the solid content of the polymerizable (meth) acrylic polymer (A). Preferably 80 to 300 parts by weight, more preferably 100 to 250 parts by weight are contained.

In the present invention, as the radical polymerization initiator, a conventional one can be appropriately used. Examples include, but are not limited to, photopolymerization initiators Irgacure 907, Irgacure 379, Irgacure 819, Irgacure OXE-01, Irgacure OXE-02, and the like.

Hereinafter, although the present invention will be described in more detail with reference to examples, it is not intended that the present invention be limited to these examples.

[Production Example 1] Production of acrylic resin (A-1) (X: Y = 80: 20)

 

 

A glass flask equipped with a heating / cooling / stirring device, a reflux condenser, and a nitrogen inlet was charged with 100 g of glycidyl methacrylate and 150 g of propylene glycol monomethyl ether acetate. After substituting the gas phase portion in the system with nitrogen, 8.7 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added, heated to 80 ° C., and reacted at the same temperature for 8 hours.
To the resulting solution were further added g of acrylic acid anhydride, 15 g of acrylic acid, 2 g of tetrabutylammonium chloride, 0.3 g of hydroquinone, and 173 g of propylene glycol monomethyl ether acetate and allowed to react at 70 ° C. for 12 hours. Thereafter, 14 g of succinic anhydride was added to the solution after the reaction and reacted at 70 ° C. for 6 hours to obtain a 40% solution of the target polymer (A-1).
The acid value in terms of solid content of this acrylic resin was 37.4. The weight average molecular weight (Mw) by GPC was 24,000.

[Production Example 2] Production of acrylic resin (A-2) (X: Y = 80: 20)

 

 

A glass flask equipped with a heating / cooling / stirring device, a reflux condenser, and a nitrogen inlet was charged with 100 g of glycidyl methacrylate and 150 g of propylene glycol monomethyl ether acetate. After the gas phase portion in the system was replaced with nitrogen, 8.7 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added, heated to 80 ° C., and reacted at the same temperature for 8 hours.
To the resulting solution, 87 g of methacrylic anhydride, 15 g of acrylic acid, 2 g of tetrabutylammonium chloride, 0.3 g of hydroquinone and 190 g of propylene glycol monomethyl ether acetate were added and reacted at 70 ° C. for 12 hours. Thereafter, 14 g of succinic anhydride was further added to the solution and reacted at 70 ° C. for 6 hours to obtain a 40% solution of the desired polymer (A-2).
The acid value in terms of solid content of this acrylic resin was 34.8. The weight average molecular weight (Mw) by GPC was 21,000.

[Production Example 3] Production of acrylic resin (A-3) (X: Y: Z = 40: 40: 20)

 

 

A glass flask equipped with a heating / cooling / stirring device, a reflux condenser, and a nitrogen inlet was charged with 100 g of glycidyl methacrylate and 150 g of propylene glycol monomethyl ether acetate. After substituting the gas phase portion in the system with nitrogen, 8.7 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added, heated to 80 ° C., and reacted at the same temperature for 8 hours.
Further, 35 g of acrylic acid anhydride, 43 g of methacrylic acid, 15 g of acrylic acid, 2 g of tetrabutylammonium chloride, 0.3 g of hydroquinone and 180 g of propylene glycol monomethyl ether acetate were added to the resulting solution and reacted at 70 ° C. for 12 hours. . Thereafter, 14 g of succinic anhydride was further added to the solution and reacted at 70 ° C. for 6 hours to obtain a 40% solution of the desired polymer (A-3).
The acid value in terms of solid content of this acrylic resin was 36.2. The weight average molecular weight (Mw) by GPC was 22,000.

[Production Example 4] Production of acrylic resin (A-4) (X: Y = 80: 20)

 

 

A glass flask equipped with a heating / cooling / stirring device, a reflux condenser, and a nitrogen inlet was charged with 100 g of glycidyl methacrylate and 150 g of propylene glycol monomethyl ether acetate. After the gas phase portion in the system was replaced with nitrogen, 8.7 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added, heated to 80 ° C., and reacted at the same temperature for 8 hours.
To the obtained solution, 51 g of acrylic acid, 2 g of tetrabutylammonium chloride, 0.3 g of hydroquinone and 110 g of propylene glycol monomethyl ether acetate were further added and reacted at 100 ° C. for 12 hours. Thereafter, 14 g of succinic anhydride was further added to the solution and reacted at 70 ° C. for 6 hours to obtain a 40% solution of the desired polymer (A-4).
The acid value in terms of solid content of this acrylic resin was 46.2. The weight average molecular weight (Mw) by GPC was 17,000.

[Production Example 5] Production of acrylic resin (A-5) (X: Y = 80: 20)

 

 

A glass flask equipped with a heating / cooling / stirring device, a reflux condenser, and a nitrogen inlet was charged with 100 g of glycidyl methacrylate and 150 g of propylene glycol monomethyl ether acetate. After the gas phase portion in the system was replaced with nitrogen, 8.7 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added, heated to 80 ° C., and reacted at the same temperature for 8 hours.
To the obtained solution, 51 g of acrylic acid, 2 g of tetrabutylammonium chloride, 0.3 g of hydroquinone and 240 g of propylene glycol monomethyl ether acetate were further added and reacted at 100 ° C. for 12 hours. After the reaction, 87 g of Karenz MOI was added and reacted at 70 ° C. for 10 hours. Thereafter, 14 g of succinic anhydride was further added to the solution and reacted at 70 ° C. for 6 hours to obtain a 40% solution of the target polymer (A-5).
The acid value in terms of solid content of this acrylic resin was 30.0. The weight average molecular weight (Mw) by GPC was 28,000.

[Production Example 6] Production of acrylic resin (A-6) (W: X: Y: Z = 20: 56: 16: 8)

 

 

100 g of glycidyl methacrylate, 39 g of dicyclopentanyl methacrylate, and 208 g of propylene glycol monomethyl ether acetate were charged into a glass flask equipped with a heating / cooling / stirring device, a reflux condenser, and a nitrogen introduction tube. After the gas phase portion in the system was replaced with nitrogen, 7.2 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added, heated to 80 ° C., and reacted at the same temperature for 8 hours.
To the obtained solution, 76 g of methacrylic anhydride, 15 g of acrylic acid, 2 g of tetrabutylammonium chloride, 0.3 g of hydroquinone and 160 g of propylene glycol monomethyl ether acetate were further added and reacted at 70 ° C. for 12 hours. Thereafter, 14 g of succinic anhydride was added to the resulting solution and reacted at 70 ° C. for 6 hours to obtain a 40% solution of the target polymer (A-6).
The acid value in terms of solid content of this acrylic resin was 32.3. The weight average molecular weight (Mw) by GPC was 25,000.

[Examples 1 to 14, Comparative Examples 1 to 8]
(1) Preparation of Photospacer Resist According to the composition shown in Table 1, 35.7 g of polymer (A-1), dipentaerythritol hexaacrylate (KAYARAD DPHA) (B-1 as polyfunctional acrylate monomer (B) ) 14.3 g, 1.5 g of photopolymerization initiator Irgacure 907 (C-1), and 48.5 g of propylene glycol monomethyl ether acetate were mixed in the dark to prepare a photospacer resist of Example 1. Examples 2 to 14 and Comparative Examples 1 to 8 in the table were similarly prepared. B-2 in the table is pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Co., Ltd., product name: PET3A).

 

 

(2) Production of Photospacer On the 10 cm × 10 cm square glass substrate, the resists of Examples and Comparative Examples were applied by a spin coater and dried to form a coating film having a dry film thickness of 3 μm. This coating film was heated on a hot plate at 90 ° C. for 2 minutes. The resulting relative coating light in the ultra-high pressure mercury lamp through a mask of photo-spacer formed with a plurality of openings was irradiated 100 mJ / cm ² (illuminance 20 mW / ^cm 2 in terms of i-line). Note that the exposure (exposure gap) between the mask and the substrate was 100 μm. Thereafter, alkali development was performed using a 0.3% K ₂ CO ₃ aqueous solution. After washing with water, post-baking was performed at 230 ° C. for 30 minutes to produce a photospacer with a thickness of 3 μm. A photo spacer having a bottom diameter of 7 μm was prepared by adjusting the mask opening diameter.

(3) Measurement of development speed It apply | coated with the spin coater on the 10 cm x 10 cm square glass substrate, it dried, and the coating film with a dry film thickness of 3 micrometers was formed. This coating film was heated on a hot plate at 90 ° C. for 2 minutes. The coating film obtained using 0.3% K ₂ CO ₃ aqueous solution was alkali-developed, and the development time until the resist residue disappeared from the substrate was measured. The results are shown in Table 2.

(4) Measurement of elastic recovery rate The elastic recovery property of the photospacer can be evaluated by the “elastic recovery rate” when a certain pressure defined by the following formula (1) is applied. The higher the elastic recovery rate (%), the better the elastic recovery characteristics.
A micro hardness tester (manufactured by Fischer Instruments; “Fischer Scope H-100”) and a planar indenter with a square cross section (50 μm × 1) are used for one photo spacer selected arbitrarily from among photo spacers formed on a glass substrate. 50 μm) was used to measure the amount of deformation when a load was applied and when it was returned. At this time, a load of 20 mN was applied over 10 seconds at a load speed of 2 mN / second and held for 5 seconds. The amount of deformation from the initial position of the photospacer in a state where a load was applied was measured. The amount of change at this time is defined as a total deformation amount T0 (μm). Next, the load was released to 0 over 10 seconds at an unloading speed of 2 mN / second, and kept in that state for 5 seconds. The deformation amount of the photo spacer at this time is defined as a plastic deformation amount T1 (μm).
From the T0 and T1 measured as described above, the elastic recovery rate was calculated using the following formula (1). The results are shown in Table 2.
Elastic recovery rate (%) = [(T0−T1) / T0] × 100 (1)

 

 

As can be seen from Table 2, the photoresist of the example takes 8 to 13 seconds until the development is completed, and the development speed is remarkably faster than that of the comparative example of 15 to 60 seconds. In the photoresists of the examples, 5 cases with an elastic recovery rate of 80% or more (42% of the whole), 4 cases with 75% to less than 80% (33% of the whole), 70% to less than 75% Compared to 3 cases (25% of the total), the photoresists of the comparative examples had no more than 80% (0% of the total), and 1 case (total of 75% to less than 80%) 13%), 2 cases with 70% to less than 75% (25% of the whole), 4 cases with 65% to less than 70% (50% of the whole), 1 case with 60% to less than 65% (whole) The photoresist of the example is remarkably excellent as a whole by the comparative example. In the resists of the comparative examples, those having an elastic recovery rate of 70 or more have development speeds of 50 seconds (Comparative Example 2), 60 seconds (Comparative Example 6), and 20 seconds (Comparative Example 8), which are particularly long. Development time is required. These results indicate that the resist of the example achieves both rapid development and excellent elastic recovery.

INDUSTRIAL APPLICABILITY The present invention can provide a cured product that exhibits good photosensitivity to active energy rays, rapid developability to an alkaline developer after exposure, and an excellent elastic recovery rate against deformation caused by external force. As useful.

Claims (12)

Monomer units (1) each having a branched side chain with 2 to 3 ends ending in radically polymerizable substituents, 2 having ends ending with carboxyl groups and ends ending with radically polymerizable substituents A monomer unit (2) with a branched side chain, or a monomer unit (3) with a side chain having one end ending with a radically polymerizable substituent, A photosensitive resin composition comprising a polymerizable (meth) acrylic polymer (A), a polyfunctional (meth) acrylate monomer (B), and a photopolymerization initiator (C). In the polymerizable (meth) acrylic polymer (A), the radical polymerizable substituent in the monomer unit (1) is a hydrocarbon chain comprising 3 to 5 carbon atoms forming a part of a side chain ( L), and the radical polymerizable substituent in the monomer unit (2) is substituted on a hydrocarbon chain (M) comprising 3 to 5 carbon atoms forming a part of the side chain. In addition, the carboxyl group is bonded to the hydrocarbon chain (M) via a group —OC (O) —Z—, and the group —Z— forming a part of the group has a carbon number 2 to 7 saturated or unsaturated chain or cyclic hydrocarbon skeleton or benzene ring, and the radical polymerizable substituent in the monomer unit (3) is a side chain Is substituted on a hydrocarbon chain comprising 3 to 5 carbon atoms forming a part of Those, the resin composition according to claim 1. The two bonding positions of the group -Z- in the monomer unit (2) are present on two adjacent carbon atoms among the carbon atoms constituting the group. Resin composition. The resin composition according to any one of claims 1 to 3, wherein the radical polymerizable substituents are independently (meth) acryloyloxy groups. The monomer unit (1) is composed of a monomer unit (1a) having an acryloyloxy group as the radical polymerizable substituent and a monomer unit (1b) having a methacryloyloxy group as the radical polymerizable substituent. The resin composition according to any one of claims 1 to 4. The molar ratio between the monomer units constituting the polymerizable (meth) acrylic polymer (A) is as follows: monomer unit (1): monomer unit (2): monomer unit (3) = 20 to 80: 5 to 50: 6. The resin composition according to claim 1, wherein the resin composition is 0-30. The polymerizable (meth) acrylic polymer (A) has the following general formula:

[In the formula, each R ₁ independently represents a hydrogen atom or a methyl group, and X ₁ , X ₂ , X ₃ and X ₄ each independently represent a substituent represented by the following general formula (1) Represents

(Wherein R ₂ represents a hydrogen atom or a methyl group, and “*-” represents a single bond),
R ₃ represents any of the substituents represented by the following structural formula,

l, m and n represent the molar ratio of each monomer unit in the form of a ratio l: m: n. 6. The resin composition according to claim 1, which is represented by the following formula: The resin composition according to claim 7, wherein in the polymerizable (meth) acrylic polymer (A), the ratio is l: m: n = 20 to 80: 5 to 50: 0 to 30. In the general formula of the polymerizable (meth) acrylic polymer (A), the following formula:

The monomer unit (1) represented by the formula (1) comprises a monomer unit (1a) in which both X ₁ and X ₂ are acryloyloxy groups, and a monomer unit (1b) in which both X ₁ and X ₂ are methacryloyloxy groups The resin composition according to claim 7 or 8, wherein The polymerizable (meth) acrylic polymer (A) has the following formula:

The composition according to any one of claims 7 to 9, which is represented by any one of the above. The polyfunctional (meth) acrylate monomer (B) is dipentaerythritol hexaacrylate, dipentaerythritol polyacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, tritriol. 11. The resin composition according to claim 1, which is selected from the group consisting of methylolpropane triacrylate, ethoxylated isocyanuric acid triacrylate, and ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate. . The polymerizable (meth) acrylic polymer (A) further comprises a monomer unit (4) different from any of the monomer units (1), (2), and (3). The resin composition according to any one of 5 to 5.