JP2017161681A - Photosensitive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition whose cured product has high reflectance, less yellowness, high resolution, and excellent adhesion.SOLUTION: The alkali-developable photosensitive resin composition is used which contains a hydrophilic resin (A) having a radically polymerizable group, a polyfunctional (meth)acrylate monomer (B), a photopolymerization initiator (C), and titanium oxide (D) as essential components. The titanium oxide (D) contains titanium oxide (D1) having a primary particle diameter of 10 nm or more and 100 nm or less and titanium oxide (D2) having a primary particle diameter of 100 nm or more and 500 nm or less.SELECTED DRAWING: None

Description

The present invention relates to a photosensitive resin composition.
Specifically, the present invention relates to a photosensitive resin composition for an opaque touch panel member such as a touch panel bezel or a backlight member such as a reflector.

In recent years, the use of touch panels has become common. In particular, the commercialization and rapid development of smartphones and tablet computers have led to the popularization and development of touch panels. In addition to the concept of touching and inputting, the touch panel device includes a concept that reflects the user's intuitive experience in the interface and further diversifies feedback for touch. In addition to being able to save space, touch panel devices can improve operability and simplicity, can easily change specifications, and are highly recognized by users. There are many advantages of being easily linked.

Due to such advantages, electronic devices can be used easily and quickly using a touch panel, and thus are widely used in various fields such as industry, transportation, service, medical care, and mobile. Such a touch panel device has been thinned in recent years, and for example, a front light-shielding layer called a bezel has also been thinned (Patent Document 1).

When a coating composition with a light color such as white or pink with low light shielding is used as the coating material for the bezel, the interior of the display is easily exposed through the bezel, so that sufficient light shielding is obtained. In addition, a method of adding a step of thickening a film has been developed (Patent Document 2). However, since this method adds an extra step, it is not suitable for a normal touch panel manufacturing process and the coating film becomes yellow. There is a problem.
Therefore, it is difficult for the conventional method to reduce both the yellowness of the coating film and improve the light hiding ratio indicated by the whiteness.

JP 2012-145699 A JP 2013-152039 A

  An object of the present invention is to provide a photosensitive resin composition in which a cured product has a high reflectance, a little yellowishness, a high resolution, and excellent adhesion.

The inventors of the present invention have reached the present invention as a result of studies to achieve the above object.
That is, the present invention contains a hydrophilic resin (A) having a radical polymerizable group, a polyfunctional (meth) acrylate monomer (B), a photopolymerization initiator (C), and titanium oxide (D) as essential components. A photosensitive resin composition comprising titanium oxide (D1) having a primary particle volume average particle diameter of 10 nm or more and less than 100 nm and titanium oxide (D2) having a primary particle diameter of 100 nm or more and 500 nm or less as titanium oxide (D). A photosensitive resin composition capable of alkali development.

  Since the photosensitive resin composition of the present invention uses titanium oxide having a large particle size and titanium oxide having a small particle size in combination, it has a high reflectance and therefore has a whiteness (L * value) and a low yellowness (b * value). ), And a pattern with high adhesion and high resolution can be formed.

The alkali-developable photosensitive resin composition of the present invention comprises a radically polymerizable organic group-containing hydrophilic resin (A), a polyfunctional (meth) acrylate monomer (B), a photopolymerization initiator (C), and titanium oxide. (D) is contained as an essential component. At that time, at least two or more kinds of titanium oxide (D1) having a volume average diameter of primary particles of 10 nm or more and less than 100 nm and titanium oxide (D2) having a volume average diameter of primary particles of 100 nm to 500 nm are different. Titanium oxide (D) is used in combination.

In this specification, “(meth) acrylate” means “acrylate or methacrylate”, “(meth) acrylic acid” means “acrylic acid or methacrylic acid”, and “(meth) acrylic resin” means “ “Acrylic resin or methacrylic resin”, “(meth) acryloyl group” means “acryloyl group or methacryloyl group”, and “(meth) acryloyloxy group” means “acryloyloxy group or methacryloyloxy group”.

  The term “alkaline developable” means that the uncured portion can be removed with an alkaline aqueous solution of the developer in the step of removing the uncured portion using a developer.

Below, (A)-(D) which is an essential structural component of the photosensitive resin composition of this invention is demonstrated in order.

The hydrophilicity index in the hydrophilic resin (A) having a radically polymerizable group, which is the first essential component in the present invention, is defined by HLB. Generally, the larger this value, the higher the hydrophilicity.
The HLB value of the hydrophilic resin (A) of the present invention is preferably 4 to 19, more preferably 5 to 19, and particularly preferably 6 to 19. When it is 4 or more, the developing property is further improved when developing the photospacer, and when it is 19 or less, the water resistance of the cured product is further improved.

Here, “HLB” is an index indicating a balance between hydrophilicity and lipophilicity, and is described in, for example, “Introduction to Surfactants” (published by Sanyo Chemical Industries, Ltd., 2007, Takehiko Fujimoto), page 212. It is known as the calculated value by the Oda method, not the calculated value by the Griffin method.
The HLB value can be calculated from the ratio between the organic value and the inorganic value of the organic compound.
The organic value and the inorganic value for deriving HLB = 10 × inorganic / organic HLB can be calculated by using the values in the table described in “Introduction of Surfactant” on page 213.

Further, the solubility parameter (hereinafter referred to as SP value) [(unit is (cal / cm ³ ) ^1/2 ]) of the hydrophilic resin (A) is preferably 7 to 14, more preferably 8 to 13, particularly preferably. Is from 9 to 13. If it is 7 or more, the developability can be further improved, and if it is 14 or less, the water resistance of the cured product is further improved.

The SP value in the present invention is calculated by the method described in the following document proposed by Fedors et al.
"POLYMER ENGINEERING AND SCIENCE, February, 1974, Vol. 14, No. 2, Robert F. Fedors (pp. 147-154)"

  The hydrophilic resin (A) of the present invention has a radical polymerizable group in the molecule, and the radical polymerizable group is preferably a (meth) acryloyl group, a vinyl group or an allyl group from the viewpoint of photocurability. More preferably, it is a (meth) acryloyl group.

  In addition, the functional group contributing to the hydrophilicity contained in the molecule of the hydrophilic resin (A) having a radical polymerizable group of the present invention is a carboxyl group, an epoxy group, a sulfonic acid group, a phosphorus group from the viewpoint of alkali developability. An acid group is preferable, and a carboxyl group is more preferable.

Examples of the hydrophilic resin (A) having a radical polymerizable group of the present invention include a hydrophilic epoxy resin (A1) and a hydrophilic acrylic resin (A2).
The hydrophilic epoxy resin (A1) can be synthesized by reacting a commercially available epoxy resin with a compound having a radical polymerizable group and further reacting with a compound having a hydrophilic functional group such as a carboxyl group. .
For example, it is produced by reacting (meth) acrylic acid with a novolak type epoxy resin having an epoxy group in the molecule, and further reacting polycarboxylic acid such as phthalic acid or phthalic anhydride or polycarboxylic acid anhydride. A method is mentioned.

  The hydrophilic acrylic resin (A2) can be obtained by polymerizing a (meth) acrylic acid derivative by an existing method and further reacting a compound having a radical polymerizable group.

  As a method for producing the hydrophilic (meth) acrylic resin (A2), radical polymerization is preferable, and a solution polymerization method is preferable because the molecular weight can be easily adjusted.

  Examples of the monomer used for producing the hydrophilic (meth) acrylic resin (A2) include (meth) acrylic acid (a21) and (meth) acrylic acid ester (a22).

  Examples of the (meth) acrylate ester (a22) include methyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylate-2-ethylhexyl, hydroxyethyl (meth) acrylate, isobornyl (meth) acrylate, and the like. Preferably, it is methyl (meth) acrylate.

  As a monomer constituting the hydrophilic (meth) acrylic resin (A2), an aromatic ring-containing vinyl compound (a23) is used in combination with (a21) and (a22) from the viewpoint of elastic recovery characteristics of the photosensitive resin composition. May be. Examples of such (a23) include styrene.

  In the hydrophilic (meth) acrylic resin (A2), it is preferable to introduce a (meth) acryloyl group into a side chain or a terminal as necessary for the purpose of further improving the elastic recovery property of the photospacer.

  Examples of the method for introducing a (meth) acryloyl group into the side chain include the following methods (1) and (2).

(1) A polymer is produced using a monomer having a group capable of reacting with an isocyanate group (such as a hydroxyl group or a primary or secondary amino group) in at least a part of (a21) or (a22); A method of reacting a compound [(meth) acryloyloxyethyl isocyanate etc.] having a (meth) acryloyl group and an isocyanate group.

(2) A polymer using a monomer having a functional group capable of reacting with an epoxy group (hydroxyl group, carboxyl group, primary or secondary amino group, etc.) in at least a part of (a21) or (a22) A method of producing and then reacting a compound having a (meth) acryloyl group and an epoxy group (such as glycidyl (meth) acrylate).

The number average molecular weight of the hydrophilic resin (A) of the present invention is 1,000 to 100,000, preferably 2,000 to 50,000.

  The content of the hydrophilic resin (A) in the photosensitive resin composition of the present invention is 5 to 62% by weight, preferably 15 based on the total weight of (A) to (D) from the viewpoint of resolution. ~ 60% by weight.

The polyfunctional (meth) acrylate monomer (B) which is the second essential component of the present invention is not particularly limited as long as it is a monomer having two or more (meth) acryloyl groups.
As such polyfunctional (meth) acrylate monomer (B), bifunctional (meth) acrylate (B1), trifunctional (meth) acrylate (B2), 4-6 functional (meth) acrylate (B3) and 7- A 10 functional (meth) acrylate (B4) is mentioned.
On the other hand, when the polyfunctional (meth) acrylate monomer (B) is not contained, or when a monofunctional (meth) acrylate monomer is used instead of (B), the resolution deteriorates.

Examples of the bifunctional (meth) acrylate (B1) include esterified products of polyhydric alcohol and (meth) acrylic acid [for example, di (meth) acrylate of glycol, di (meth) acrylate of glycerin, dimethyl methacrylate). (Meth) acrylate, di (meth) acrylate of 3-hydroxy-1,5-pentanediol, di (meth) acrylate of 2-hydroxy-2-ethyl-1,3-propanediol]; alkylene oxide of polyhydric alcohol Adducts and esterified products of (meth) acrylic acid [for example, di (meth) acrylate of trimethylolpropane ethylene oxide adduct, di (meth) acrylate of glycerin ethylene oxide adduct]; OH group-containing both-end epoxy acrylate; Polyhydric alcohol and (meth) acryl Esters of acids and hydroxy carboxylic acids [e.g. hydroxypivalic acid neopentyl glycol di (meth) acrylate], and the like.
In addition, it is not necessary to make all the hydroxyl groups of a polyhydric alcohol react with (meth) acrylic acid, an alkylene oxide adduct, etc., and unreacted hydroxyl groups may remain.

Trifunctional (meth) acrylate (B2) includes tri (meth) acrylate of glycerol, tri (meth) acrylate of trimethylolpropane, tri (meth) acrylate of pentaerythritol; and trioxide of ethylene oxide adduct of trimethylolpropane. (Meth) acrylate etc. are mentioned.

Examples of tetra to hexafunctional (meth) acrylate (B3) include pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate; dipentaerythritol ethylene oxide addition Tetra (meth) acrylate of a product, penta (meth) acrylate of an ethylene oxide adduct of dipentaerythritol, penta (meth) acrylate of a propylene oxide adduct of dipentaerythritol, and the like.

  Examples of 7-10 functional (meth) acrylate compounds (B4) include diisocyanate compounds and hydroxyl group-containing polyfunctional (meth) acrylate compounds such as compounds obtained by reaction of dipentaerythritol penta (meth) acrylate and hexamethylene diisocyanate. It can obtain by reaction of.

  Of the polyfunctional (meth) acrylate monomer (B), from the viewpoint of curability, it is preferably a trifunctional or higher functional (meth) acrylate monomer, and more preferably a trifunctional or higher functional group having a glycerin, pentaerythritol or dipentaerythritol skeleton. It is a (meth) acrylate monomer.

  The content of the polyfunctional (meth) acrylate monomer (B) in the photosensitive resin composition of the present invention is preferably 5 to 62% by weight based on the total weight of (A) to (D) from the viewpoint of curability. Is 20 to 60% by weight.

As the photoinitiator (C) which is the third essential component of the present invention, polymerization of the polymerizable unsaturated compound is initiated by exposure to radiation such as visible light, ultraviolet light, far infrared light, charged particle beam and X-ray. Any component that can generate a free radical may be used.

As the photopolymerization initiator (C), α-hydroxyalkylphenone type (C-1) (for example, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, etc.); α-aminoalkylphenone type (C-2) (for example, (2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1 -(4-morpholinophenyl) -butanone-1 etc.); thioxanthone compound type (C-3) (eg, (isopropylthioxanthone, diethylthioxanthone etc.); phosphate ester type (C-4) (eg, (2, 4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine Oxides); acyloxime type (C-5) (for example, 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], ethanone, 1- [9- Ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime) etc.); benzyldimethyl ketal type (C-6) etc .; benzophenone type (C-7) (For example, benzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, etc.).

It is preferable that at least one of the photopolymerization initiators (C) has absorbance at a wavelength of 400 nm or more from the viewpoint of curability. For example, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one [Irgacure 369 (manufactured by BASF, extinction coefficient at 405 nm: 280)], bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide [Irgacure 819 (manufactured by BASF, extinction coefficient at 405 nm: 899)], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide [lucillin TPO (manufactured by BASF, Extinction coefficient at 405 nm: 165)], 1,2-octanedione 1- [4- (phenylthio)-, 2- (O-benzoyloxime)] [Irgacure OXE01 (manufactured by BASF, extinction coefficient at 405 nm: 102 )] And the like.

  Of these, from the viewpoint of curability of the cured product, a phosphate ester type initiator is preferable, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-) is more preferable. Trimethylbenzoyl) -phenylphosphine oxide.

  The usage-amount of a photoinitiator (C) is 3-20 weight% from a viewpoint of sclerosis | hardenability and coloring of hardened | cured material based on the sum total of (A)-(D), Preferably it is 5-15 weight%.

  Titanium oxide (D), which is the fourth essential component in the photosensitive resin composition of the present invention, is an essential component from the viewpoint of whiteness for increasing the reflectance.

Since titanium oxide has different whiteness depending on its production method, it is preferable to select titanium oxide having high whiteness in order to improve reflectivity. Impurities of heavy metals and metal oxides mixed during the purification of titanium oxide have an adverse effect on whiteness, and coloring with Fe, Cr, Cu, Mn, V, Nb, etc. is particularly harmful. Therefore, it is preferable to limit heavy metal and metal oxide impurities to 0.1 wt% or less as impurities.

  Titanium oxide having an impurity content of 0.1% by weight or less can be prepared by surface-treating rutile titanium oxide preferably made by a chlorine method with alumina, silica, zirconia, titania, organic matter, or the like.

In the present invention, titanium oxide (D) is a combination of titanium oxide (D1) having a primary particle volume average diameter of 10 nm or more and less than 100 nm and titanium oxide (D2) having a primary particle diameter of 100 nm or more and 500 nm or less. The primary particle diameter of titanium oxide (D1) is further preferably 30 nm or more and less than 100 nm, while the primary particle diameter of titanium oxide (D2) is more preferably 100 nm or more and 400 nm or less.

Only titanium oxide (D1) with a primary particle diameter of 10 nm or more and less than 100 nm has insufficient concealment, so whiteness has not been achieved. Whiteness is achieved only with titanium oxide (D2) with a primary particle diameter of 100 nm or more and 500 nm or less. If you do, the yellowness will not be achieved.
In addition, this primary particle diameter measures the single particle diameter when observed using an electron microscope (VE-9800, Keyence Corporation make), and calculates the volume average particle diameter with image analysis software.

Examples of the chlorinated titanium oxide include Taipur R900 and R920 (manufactured by DuPont), Taipaque CR50, CR58, CR67, PFC-105 and PFC-107 (manufactured by Ishihara Sangyo).

Based on the total weight of (A) to (D) in the photosensitive resin composition of the present invention, the total content of (D) of titanium oxides (D1) and (D2) is 30 to 87% by weight, preferably Is 35 to 85% by weight.
If it is 30% by weight or more, the reflectance is good, and if it is 90% by weight or less, the handling property during coating can be further improved.

Further, the content ratio of (D1) and (D2) in titanium oxide (D) is preferably 1/99 to 50/50 in weight ratio (D1) / (D2) from the viewpoint of whiteness and yellowness. Is 2/98 to 45/55.
If the weight ratio (D1) / (D2) is less than 1/99, the yellowness deteriorates, and if it exceeds 50/50, the whiteness deteriorates.

The photosensitive resin composition according to the present invention may further contain other components as necessary.
Other components include monofunctional (meth) acrylates (E) other than (A) and (B), leveling agents (F), antioxidants (G), extender pigments (barium sulfate and tie), sensitizers , Polymerization inhibitors, solvents, pigment dispersants, thickeners and other additives (for example, fluorescent brighteners and yellowing inhibitors).

The monofunctional (meth) acrylate (E) in the present invention is preferably a (meth) acrylate having a phosphate group, a carboxyl group or a hydroxyl group, more preferably a (meth) having a phosphate group, from the viewpoint of adhesion. Acrylate.
Examples of the (meth) acrylate containing a hydroxyl group include hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, and examples of the (meth) acrylate having a phosphate group include 2- (meth) acryloyloxyethyl acid. A phosphate etc. are mentioned.

  The content of the monofunctional (meth) acrylate (E) is preferably 0 to 20% by weight based on the total weight of (A) to (D) in the photosensitive resin composition of the present invention, more preferably 0.8. 5 to 15% by weight, particularly preferably 1 to 10% by weight.

  Examples of the leveling agent (F) include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, fluorine surfactants, and silicon surfactants. Of these, fluorine surfactants and silicon surfactants are preferable from the viewpoint of coatability, and surfactants having an oxyalkyl chain are preferable from the viewpoint of compatibility.

  Examples of the antioxidant (G) include phenol-based antioxidants, sulfur-based antioxidants, and amine-based antioxidants. Among these, from the viewpoint of photocurability and antioxidant ability, phenolic antioxidants are preferable, and 2,6-di-t-butyl-4-methylphenol (BHT) and 2-t-butyl are particularly preferable. -6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl]- 4,6-di-t-pentylphenyl acrylate, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate (Irganox 1076), thiodiethylene bis [3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate (Irganox 1035), ethylenebis (oxyethylene) bis [3- (5-tert Butyl-4-hydroxy-m-tolyl) propionate] (Irganox 245), hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 259), pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (Irganox 1010).

  Solvents include ketone solvents (such as cyclohexanone), ether solvents (including ether ester solvents and ether alcohol solvents) (such as propylene glycol monomethyl ether acetate and methoxybutyl acetate), ester solvents (such as butyl acetate), ether solvents (ether ester) Solvents, ether alcohol solvents, etc.), alcohol solvents (including ketone alcohol solvents) (1.3-butylene glycol and diacetone alcohol, etc.), ester solvents (ethyl lactate, etc.), ketone solvents (acetone, methyl ethyl ketone, etc.), etc. It is done.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

Production Example 1 [Production of hydrophilic epoxy resin (A-1) having a radical polymerizable organic group]
A glass Kolben equipped with a heating / cooling / stirring device, a reflux condenser, a dropping funnel and a nitrogen introduction tube, cresol novolac type epoxy resin “EOCN-102S” (Epoxy equivalent 200 from Nippon Kayaku Co., Ltd.) and propylene 245 parts of glycol monomethyl ether acetate was charged and heated to 110 ° C. to dissolve uniformly. Subsequently, 76 parts of acrylic acid (1.07 mol part), 2 parts of triphenylphosphine and 0.2 part of p-methoxyphenol were charged and reacted at 110 ° C. for 10 hours.
The reaction product was further charged with 91 parts (0.60 mole part) of tetrahydrophthalic anhydride, reacted at 90 ° C. for 5 hours, and then the hydrophilic resin content was adjusted to 50% by weight with propylene glycol monomethyl ether acetate. Dilution was performed to obtain a 50% propylene glycol monomethyl ether acetate solution of a carboxyl group-containing cresol novolac epoxy resin (A-1) as a hydrophilic resin having an acryloyl group and a carboxyl group of the present invention. The SP value was 11.3 and the HLB value was 6.4.

Production Example 2 [Production of hydrophilic acrylic resin (A-2) having radical polymerizable organic group]
172 parts of propylene glycol monomethyl ether acetate was charged into a glass Kolben equipped with a heating / cooling / stirring device, a reflux condenser, a dropping funnel, and a nitrogen introduction tube, and heated to 90 ° C. A solution in which 177 parts of methacrylic acid, 13 parts of methyl methacrylate, 395 parts of styrene, and 207 parts of propylene glycol monomethyl ether acetate were uniformly mixed, and dimethyl-2,2′-azobis (2-methylpropionate) 5 A solution in which 12 parts of propylene glycol monomethyl ether acetate were uniformly mixed was dropped, and radical polymerization was performed in glass Kolben to obtain an acrylic resin.
The acrylic resin was further charged with 19 parts of glycidyl methacrylate, reacted at 90 ° C. for 5 hours, and then diluted with propylene glycol monomethyl ether acetate so that the hydrophilic resin content was 30% by weight. A 30% propylene glycol monomethyl ether acetate solution of an acrylic resin (A-2) having a group was obtained.
The SP value of this resin was 10.5, and the HLB value was 5.8.

Comparative Production Example 1 [Production of hydrophilic acrylic resin (A′-1) having no radically polymerizable organic group]
172 parts of propylene glycol monomethyl ether acetate was charged into a glass Kolben equipped with a heating / cooling / stirring device, a reflux condenser, a dropping funnel, and a nitrogen introduction tube, and heated to 90 ° C. A solution in which 177 parts of methacrylic acid, 13 parts of methyl methacrylate, 395 parts of styrene, and 207 parts of propylene glycol monomethyl ether acetate were uniformly mixed, and dimethyl-2,2′-azobis (2-methylpropionate) 5 Part of the solution and 12 parts of propylene glycol monomethyl ether acetate were added dropwise, and radical polymerization was performed in glass Kolben. Thereafter, the resin is diluted with propylene glycol monomethyl ether acetate so that the hydrophilic resin content is 30% by weight, and 30% propylene glycol of an acrylic resin (A′-1) having no radical polymerizable group used in the comparative example. A monomethyl ether acetate solution was obtained.
The SP value of this resin was 11.0, and the HLB value was 6.1.

Production Example 3 [Production of Titanium Oxide (D1-1) Dispersion with Volume Average Particle Diameter of 40 nm]
A SUS flask equipped with a stirrer was charged with 500 parts of propylene glycol monomethyl ether acetate and 80 parts of phosphoric acid polyester (trade name: DISPERBYK-111, manufactured by Big Chemie Japan Co., Ltd.) as a dispersing agent. Here, 420 parts of titanium oxide having a primary particle diameter of 40 nm (trade name: TTO-55, volume average particle diameter of primary particles according to catalog values 40 nm, manufactured by Ishihara Sangyo Co., Ltd.) was charged and stirred and dispersed.
This dispersed liquid was transferred to a 250 mL plastic container, and zirconia beads having a particle size of 0.5 mm were further charged therein and dispersed for 1 hour using a paint shaker.
After the completion of dispersion, zirconia beads were removed by filtration through 300 mesh to obtain a 50% dispersion of titanium oxide (D-1).

Production Example 4 [Production of Titanium Oxide (D2-1) Dispersion with Volume Average Particle Diameter of 250 nm]
The titanium oxide of Production Example 4 was converted to titanium oxide having a primary particle diameter of 250 nm (trade name: CR-57, volume average particle diameter of primary particles: 250 nm, manufactured by Ishihara Sangyo Co., Ltd.), and phosphoric acid polyester (trade name: A 50% dispersion of titanium oxide (D-2) was obtained in the same manner as in Production Example 3, except that the solvent was changed to Solsperz 36000, manufactured by Lubrizol Corporation.

Production Example 5 [Production of a dispersion of titanium oxide (D2-2) having a volume average particle diameter of 280 nm]
Except for changing the titanium oxide of Production Example 4 to titanium oxide having a primary particle size of 280 nm (trade name: PFC-105, primary particle size of 280 nm, manufactured by Ishihara Sangyo Co., Ltd.), the same method as in Production Example 3, A 50% dispersion of titanium oxide (D-3) was obtained.

Example 1
According to the number of parts (parts by weight) in Table 1, a 50% propylene glycol monomethyl ether acetate solution of the hydrophilic epoxy resin (A-1) produced in Production Example 1 in a glass container, (B-1), Irgacure 819 ( C-1), titanium oxide (D1-1) dispersion produced in Production Example 3, titanium oxide (D2-2) dispersion produced in Production Example 4, light acrylate P-1A (E-1), leveling agent As a polyether-modified polydimethylsiloxane “KF-352A” (F-1) as an antioxidant and Irganox 1010 (G-1) as an antioxidant, followed by stirring at 25 ° C. for 2 hours, and additional solvent (propylene glycol) Monomethyl ether acetate) was added and stirred for 30 minutes to obtain a photosensitive resin composition of Example 1.

Examples 2-6 and Comparative Examples 1-6
By the same operation as Example 1, the photosensitive resin composition of Examples 2-6 and Comparative Examples 1-6 was obtained by the mixing | blending part number of Table 1.

The details of the abbreviated chemicals in Table 1 are as follows.
(B-1): “Neomer DA-600” (dipentaerythritol pentaacrylate: manufactured by Sanyo Chemical Industries, Ltd .; 6 functional groups)
(B-2): “Neomer EA-300” (pentaerythritol tetraacrylate: Sanyo Chemical Industries, Ltd .; 4 functional groups)
(B′-1): “Light acrylate PO-A” (phenoxyethyl acrylate: manufactured by Kyoeisha Chemical Co., Ltd .; one functional group)
(C-1): “Irgacure 819” (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide: manufactured by BASF Corporation))
(C-2): “Irgacure 907” (2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one: manufactured by BASF Corporation)
(C-3): “Lucirin TPO” ((2,4,6-trimethylbenzoyl) -diphenylphosphine oxide: manufactured by BASF Corporation))
(E-1): “Light acrylate P-1A” (2-acryloyloxyethyl acid phosphate: manufactured by Kyoeisha Chemical Co., Ltd.)
(E-2): “KBM-5103” (acrylic-modified alkoxysilane: manufactured by Shin-Etsu Chemical Co., Ltd.)
(F-1): Polyether-modified polydimethylsiloxane (“KF-352A”: manufactured by Shin-Etsu Chemical Co., Ltd.)
(F-2): Polyether-modified fluorine compound (“Megafac TF-2066”: manufactured by DIC Corporation)
(G-1): Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (“Irganox 1010”: manufactured by BASF Japan Ltd.)

Hereinafter, a method for evaluating the whiteness, yellowness, adhesion, and resolution of the cured product will be described.

<Evaluation of whiteness and yellowness>
[Creation of substrates for measuring whiteness and yellowness]
It apply | coated with the spin coater on the 10 cm x 10 cm square glass substrate, and the coating film with a dry film thickness of 20 micrometers was formed. This coating film was completely dried under reduced pressure and then heated on a hot plate at 80 ° C. for 3 minutes.
The obtained coating film was irradiated with light of an ultrahigh pressure mercury lamp at 100 mJ / cm ² (illuminance 22 mW / cm ^{2 in} terms of i-line), and further heated at 230 ° C. for 30 minutes to measure whiteness and yellowness. The board of was made.

Using a spectrocolorimeter ("Konica Minolta" CM3700d ", light source C is used) used for measuring the object color in accordance with JIS Z 8722, the above cured product is measured for whiteness (L *) and yellowness ( b *) was measured.
In order to be used for the bezel portion of the touch panel, the whiteness under this evaluation condition is generally required to be 90 or more and the yellowness is 0 or less.

<Evaluation of adhesion>
In accordance with JIS K 5600-5-6, the cured product whose whiteness is measured is cut into a 1 mm width with a cutter knife so as to form 100 (10 × 10) cells, and the resin adhesion is measured.
The measurement result is expressed as “the grid remaining on the base film after the test / 100”.
In this evaluation condition, 100/100 is generally required.

[Preparation of resolution confirmation cured pattern]
A 10 cm × 10 cm square glass substrate was coated with a spin coater and dried to form a coating film having a dry film thickness of 5 μm. This coating film was heated on a hot plate at 80 ° C. for 3 minutes to completely evaporate the solvent.
The obtained dried coating film was irradiated with light of an ultrahigh pressure mercury lamp at 100 mJ / cm ² through a plurality of line forming masks having an opening having a length of about 2 cm and a width of 50 μm every 100 μm (i-line conversion) Illuminance of 22 mW / cm ² ).
In addition, the exposure (exposure gap) between the mask and the substrate was 100 μm.
Thereafter, alkali development was performed using a 0.05% aqueous KOH solution. After washing with water, post-baking was performed at 230 ° C. for 30 minutes, and 100 rectangular patterns of 2 cm × 50 μm were formed on a glass substrate every 100 μm.
A rectangular pattern having a desired width can be formed by adjusting the mask opening diameter.

<Evaluation of resolution>
As the touch panel has become narrower, high-definition patterns can be formed. That is, patterning with a resolution of 50 μm or less has been required.
That is, the higher the resolution, the better the performance of forming a pattern having the same size as the mask opening diameter even if the mask opening diameter is reduced.
Therefore, the resolution was evaluated by setting the opening diameter of the mask to 50 μm and measuring the width of the pattern when the pattern was formed by the above method.
The smaller the bottom diameter, the higher the resolution. In this evaluation method and conditions, generally 80 μm or less is preferable.

As shown in Table 1, the photosensitive resin compositions of Examples 1 to 6 of the present invention are excellent in all points of whiteness, yellowness, adhesion, and resolution.
On the other hand, in Comparative Example 1 in which the hydrophilic resin (A) having a radical polymerizable group of the present invention is not used, adhesion and resolution are not satisfied. Moreover, the comparative example 2 which does not use a polyfunctional acrylate (B) and the comparative example 3 which uses a monofunctional acrylate instead of a polyfunctional acrylate (B) do not satisfy resolution. Furthermore, in Comparative Examples 4 and 5 in which titanium oxide (D1) having a primary particle size of 10 nm to 100 nm is not used, whiteness and yellowness are deteriorated, and titanium oxide (D2) having a primary particle size of 100 nm to 500 nm is used. In Comparative Example 6, the whiteness deteriorates

  The photosensitive resin composition of the present invention is excellent in whiteness and yellowness after curing, adhesion and resolution, so that it is an opaque touch panel member such as a touch panel bezel or a flexible display bezel, or a reflector used in a display It can be suitably used as a backlight member.

Claims (6)

  Photosensitivity containing, as essential components, a hydrophilic resin (A) having a radical polymerizable organic group, a polyfunctional (meth) acrylate monomer (B), a photopolymerization initiator (C), and titanium oxide (D). It is a resin composition, and titanium oxide (D1) whose primary particles have a volume average particle diameter of 10 nm or more and less than 100 nm and titanium oxide (D2) whose primary particle diameter is 100 nm or more and 500 nm or less are used in combination as titanium oxide (D). A photosensitive resin composition capable of alkali development.   The photosensitive resin composition according to claim 1, wherein the content of titanium oxide (D) is 30 to 87% by weight based on the total weight of (A) to (D). The photosensitive resin composition according to claim 1 or 2, wherein the weight ratio (D1) / (D2) of titanium oxide (D1) to titanium oxide (D2) is 1/99 to 50/50.   The photosensitive resin composition according to any one of claims 1 to 3, wherein at least one of the photopolymerization initiators (C) is a photopolymerization initiator having absorbance at a wavelength of 400 nm or more. The photosensitive resin composition according to any one of claims 1 to 4, wherein the content of the photopolymerization initiator (C) is 3 to 20% by weight based on the total weight of (A) to (D). The photosensitive resin composition according to claim 1, wherein the content of the hydrophilic resin (A) is 5 to 62% by weight based on the total weight of (A) to (D).