JP2011132349A - Inkjet ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide inkjet ink which has excellent jetting properties and photocurability of the ink, of which the cured film has excellent adhesion to a substrate, and which forms a microlens array exhibiting high transmittance and high strength. <P>SOLUTION: A photocurable inkjet ink contains a specific trifunctional (meth)acrylic acid ester (A), a monofunctional (meth)acrylate (B), and a photopolymerization initiator (C). The cured film (film thickness of 5 μm) obtained from the ink has transmittance at 400 nm of 96% or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an ink-jet ink that is suitably used for manufacturing an optical apparatus such as a liquid crystal display or a display panel. More specifically, the present invention relates to an inkjet ink suitable for a microlens array used in a backlight device.

For some time, transmissive or transflective LCDs that display using backlight light have been used for liquid crystal display elements such as liquid crystal displays. Such a transmissive or transflective LCD has a structure in which an opening is provided in a reflection plate inside the LCD and backlight is transmitted through the opening to display. Thus, a light guide plate in which a microlens array is arranged between a liquid crystal display panel and a backlight has been proposed in order to eliminate luminance unevenness when transmitting backlight light. (For example, Unexamined-Japanese-Patent No. 2003-107505 (patent document 1)).
Conventionally, in the injection molding method that has been performed as a method for manufacturing such a light guide plate, it is necessary to produce a plurality of molds, which requires much time and cost. Moreover, when it manufactures using the said manufacturing method, the patterning precision of a resin lens is bad, and a brightness nonuniformity tends to generate | occur | produce.

  In order to solve these problems, a method of forming a microlens array by applying a photosensitive material directly on a substrate using an ink jet method has been developed in recent years (for example, JP-A-5-303017 (patent) Document 2), JP 2000-180605 A (Patent Document 3), JP 2004-240294 A (Patent Document 4)). As described above, the resin lens manufacturing method using the ink jet method can easily control patterning with electronic data such as a personal computer without producing a conventional mold. However, there is an expectation from the point that the manufacturing cost can be suppressed.

  In addition, various ink compositions have been proposed as photosensitive materials used in the inkjet method (for example, Japanese Patent Application Laid-Open No. 2004-117955 (Patent Document 5) and Japanese Patent Application Laid-Open No. 2005-340467 (Patent Document 6)). ), Japanese Patent Application Laid-Open No. 2006-208734 (Patent Document 7) and Japanese Patent Application Laid-Open No. 2007-24970 (Patent Document 8)), and the microlens array formed with these inks has sufficient photocurability and adhesion to the substrate. Performance, high transmittance and high strength are not satisfied.

On the other hand, various inks have been proposed as photosensitive materials having excellent photocurability and adhesion to a substrate (for example, JP-A-2-6562 (Patent Document 9), JP-A-7-53895 ( Patent Document 10), Japanese Patent Application Laid-Open No. 7-70472 (Patent Document 11), Japanese Patent Application Laid-Open No. 2003-192934 (Patent Document 12), Japanese Patent Application Laid-Open No. 2005-162882 (Patent Document 13), and WO 2006-129530 ( Patent Document 14), Japanese Patent Application Laid-Open No. 2007-231231 (Patent Document 15) and Japanese Patent Application Laid-Open No. 2007-231233 (Patent Document 16)).
However, JP-A-2-6562 (Patent Document 9), JP-A-7-53895 (Patent Document 10), and JP-A-7-70472 (Patent Document 11) are cured films estimated from examples. Although the transmittance of is high, it does not have sufficient strength.

  Furthermore, JP 2003-192943 A (Patent Document 12), JP 2005-162882 A (Patent Document 13), WO 2006-129530 pamphlet (Patent Document 14), JP 2007-233131 A (Patent Document 15). ), JP-A-2007-231233 (Patent Document 16) has a low transmittance because colorants such as dyes and pigments are added to any of the compositions. Even when an additive-free composition is used, it is presumed that the transmittance is low and it does not have sufficient performance.

JP 2003-107505 A JP-A-5-303017 JP 2000-180605 A JP 2004-240294 A JP 2004-117955 A JP 2005-340467 A JP 2006-208734 A JP 2007-24970 A JP-A-2-6562 JP-A-7-53895 JP-A-7-70472 JP 2003-192943 A Japanese Patent Laid-Open No. 2005-162882 International Publication No. 2006-129530 Pamphlet JP 2007-231231 A JP 2007-231233 A

  Under the circumstances described above, an object of the present invention is to provide an ink-jet ink that is capable of forming a microlens array having excellent photocurability and adhesion to a substrate and exhibiting high transmittance and strength. There is.

The present inventors have disclosed that a photocurable inkjet ink containing a (meth) acrylic acid ester represented by the formula (1), a monofunctional (meth) acrylate, and a photopolymerization initiator is photocurable, The inventors have found that a microlens array having excellent adhesion, high transmittance, and high strength can be formed, and the present invention has been completed based on this finding. Furthermore, the present invention provides a microlens array obtained from such an inkjet ink and uses of the microlens array.
That is, the present invention includes the following items.

（式中、Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４はそれぞれ独立に水素又は炭素数が１〜６のアルキルであり、Ｒ^５、Ｒ^６、Ｒ^７及びＲ^８はそれぞれ独立に炭素数が１〜６のアルキレンであり、ｋは０又は１であり、ｌ、ｍ、及びｎはそれぞれ独立に１〜１０の整数である。） [1] A photocurable inkjet ink containing a (meth) acrylic acid ester (A) represented by the formula (1), a monofunctional (meth) acrylate (B), and a photopolymerization initiator (C). A photocurable inkjet ink in which the cured film (film thickness: 5 μm) obtained from the ink has a transmittance of 96% or more at 400 nm.

(In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or alkyl having 1 to 6 carbon atoms, and R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently carbon number. Is alkylene of 1-6, k is 0 or 1, and l, m, and n are each independently an integer of 1-10.)

[2] 30 to 70% by weight of (meth) acrylic acid ester (A) represented by formula (1), 20 to 60% by weight of monofunctional (meth) acrylate (B), based on the total weight of the ink, The inkjet ink according to [1], containing 1 to 20% by weight of the photopolymerization initiator (C).

[3] The inkjet ink according to [1] or [2], wherein in formula (1), R ⁵ , R ⁶ , and R ⁷ are each independently alkylene having 2 or 3 carbon atoms.

[4] The inkjet ink according to any one of [1] to [3], wherein in formula (1), R ¹ is hydrogen and k is 0.

[5] The inkjet ink according to any one of [1] to [4], wherein in formula (1), l, m, and n are 1.

[6] The inkjet ink according to any one of [1] to [5], wherein the monofunctional (meth) acrylate (B) is a monofunctional (meth) acrylate having an alkyl having 1 to 6 carbon atoms.

[7] Monofunctional (meth) acrylate (B) is cyclohexyl (meth) acrylate, n-hexyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate, The inkjet ink according to any one of [1] to [6], which is at least one selected from the group consisting of ethyl (meth) acrylate or methyl (meth) acrylate.

[8] The inkjet ink according to any one of [1] to [7], wherein the photopolymerization initiator (C) is an α-hydroxylalkylphenone-based or acylphosphine oxide-based photopolymerization initiator.

[9] The inkjet ink according to any one of [1] to [8], further containing a polymerization inhibitor.

[10] Ethylene oxide-modified glycerol triacrylate (ethylene oxide modification: 3 mol) as (meth) acrylic acid ester (A) represented by formula (1), n-butyl (monofunctional (meth) acrylate (B) as The inkjet ink according to [9], which contains (meth) acrylate, 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator (C), and phenothiazine as a polymerization inhibitor.

[11] A cured film obtained by curing the inkjet ink according to any one of [1] to [10].

[12] A microlens array obtained from the cured film according to [11].

[13] An optical apparatus having the microlens array according to [12].

  The inkjet ink of the present invention is excellent in jetting and photocurability of the coating film of the ink, the cured film obtained from the ink is excellent in adhesion to the substrate, and the microlens array obtained from the cured film is high. Transmittance and high strength.

（式中、Ｒ^１、Ｒ^２、Ｒ^３、及びＲ^４はそれぞれ独立に水素又は炭素数が１〜６のアルキルであり、Ｒ^５、Ｒ^６、Ｒ^７及びＲ^８はそれぞれ独立に炭素数が１〜６のアルキレンであり、ｋは０又は１であり、ｌ、ｍ、及びｎはそれぞれ独立に１〜１０の整数である。） [1. Ink for inkjet of the present invention]
The ink-jet ink of the present invention (hereinafter also simply referred to as “the ink of the present invention”) comprises (meth) acrylic acid ester (A) represented by formula (1) in an amount of 30 to 70% by weight based on the total weight of the ink. A photocurable inkjet ink containing monofunctional (meth) acrylate (B) in an amount of 20 to 60% by weight based on the total weight of the ink and a photopolymerization initiator (C) in an amount of 1 to 20% based on the total weight of the ink. Then, the photocurable ink-jet ink was obtained by forming a 3 cm square coating film by photo-curing the 3 cm square coating film by applying the ink to the central part on a 4 cm square glass substrate. This is a photocurable inkjet ink that exhibits a transmittance of 96% or more at 400 nm of a glass substrate having a cured film (film thickness: 5 μm).

(In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or alkyl having 1 to 6 carbon atoms, and R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently carbon number. Is alkylene of 1-6, k is 0 or 1, and l, m, and n are each independently an integer of 1-10.)

  The ink of the present invention may be colorless or colored. Colorless is preferable from the viewpoint of transmittance, but a colored compound may be contained as long as the effects of the invention are not hindered. Further, for example, a colorant may be included in order to facilitate identification from the substrate when the state of the cured film is inspected.

  In this specification, “(meth) acrylate” is used to indicate both or one of acrylate and methacrylate.

In addition, the ink of the present invention contains a phenol resin, a melamine resin, an epoxy resin, an epoxy curing agent, a surfactant, another compound having a radical polymerizable double bond, a solvent, a polymerization inhibitor, and the like as necessary. be able to. Here, the “compound having another radical polymerizable double bond” is a compound other than the (meth) acrylic acid ester (A) and the monofunctional (meth) acrylate (B) represented by the formula (1). is there.
Hereinafter, the viscosity of each of the above components and the ink of the present invention will be described.

<1.1. Viscosity of Inkjet Ink of the Present Invention>
The viscosity of the inkjet ink of the present invention at 25 ° C. measured with an E-type viscometer is preferably 200 mPa · s or less, and more preferably 1 to 200 mPa · s. When the pressure is 1 to 200 mPa · s, the jetting characteristics of the ink jet apparatus are good. The viscosity of the ink of the present invention at 25 ° C. is more preferably 2 to 150 mPa · s, and particularly preferably 3 to 100 mPa · s.

  In addition, the viscosity of the ink of the present invention at a temperature (preferably 10 to 120 ° C.) when ejected by an ink jet coating apparatus is preferably 1 to 30 mPa · s, and more preferably 2 to 25 mPa · s. 3 to 20 mPa · s is particularly preferable.

  When an ink having a viscosity at 25 ° C. exceeding 30 mPa · s is used, the ink jet head is heated to lower the viscosity of the ink at the time of ejection, thereby enabling more stable ejection. When jetting by heating the inkjet head, the viscosity of the inkjet ink at the heating temperature (preferably 40 to 120 ° C.) is preferably 1 to 30 mPa · s, and preferably 2 to 25 mPa · s. Further preferred is 3 to 20 mPa · s.

  When heating the inkjet head, it is preferable to use an ink containing no solvent.

<1.2. (Meth) acrylic acid ester (A) represented by formula (1)>
By using the (meth) acrylic acid ester (A) represented by the formula (1), the ink of the present invention is excellent in photocurability. The cured film formed from the ink of the present invention is excellent in adhesion to the substrate and exhibits high transmittance and high strength. Furthermore, the microlens array obtained from the cured film has excellent adhesion to the substrate, and exhibits high transmittance and high strength.

In the formula (1), R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or alkyl having 1 to 6 carbon atoms, and R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently Is alkylene having 1 to 6 carbon atoms, k is 0 or 1, and l, m, and n are each independently an integer of 1 to 10.

Among them, when R ¹ is hydrogen, CH ₃ , or CH ₂ CH ₃ and k is 0, the photocurability of the ink of the present invention is good, and the obtained cured film has a high transmittance, It is preferable because it shows high strength. Furthermore, it is preferable that R ¹ is hydrogen because the transmittance of the cured film becomes higher. R ² , R ³ , and R ⁴ are preferably hydrogen or CH ₃ from the viewpoint of photocurability, and more preferably hydrogen. R ⁵ , R ⁶ , and R ⁷ are preferably ethylene, propylene, or butylene, and more preferably ethylene, from the viewpoint of the balance between the transmittance and strength of the cured film obtained from the ink.

  Specific examples of the (meth) acrylic acid ester represented by the formula (1) include trimethylolpropane PO-modified (3 mol) triacrylate, trimethylolpropane PO-modified (6 mol) triacrylate, trimethylolpropane PO-modified ( 9 mol) Triacrylate, trimethylolpropane EO modified (3 mol) triacrylate, trimethylolpropane EO modified (6 mol) triacrylate, trimethylolpropane EO modified (9 mol) triacrylate, PO modified (3 mol) glycerin tri Acrylate, PO-modified (6 mol) glycerin triacrylate, PO-modified (9 mol) glycerin triacrylate, EO-modified (3 mol) glycerin triacrylate, EO-modified (6 mol) glycerin triacrylate, EO-modified (9 mol) glycerin Triacrylate. “EO modification” represents ethylene oxide modification and “PO modification” represents propylene oxide modification, and the number of moles in parentheses indicates the number of ethylene oxide or propylene oxide added per molecule.

  Among these, in particular, when trimethylolpropane PO-modified (3 mol) triacrylate and EO-modified (3 mol) glycerin triacrylate are used, the ink of the present invention is not only excellent in photocurability, but also has a high transmittance and substrate. A cured film having a good balance between adhesion and strength can be obtained, and among them, when EO-modified (3 mol) glycerin triacrylate is used, the cured film has the highest transmittance and is excellent.

  The (meth) acrylic acid ester (A) represented by the formula (1) may be one kind of compound selected from the above-mentioned compounds or the like, or may be a mixture of two or more kinds thereof.

  As described above, the (meth) acrylic acid ester (A) represented by the formula (1) described above can be produced by a known method, and is also commercially available. For example, trimethylolpropane PO-modified (3 mol) triacrylate (M-310: trade name; manufactured by Toagosei Co., Ltd.), trimethylolpropane PO-modified (6 mole) triacrylate (M-320: trade name; Toagosei) Co., Ltd.), trimethylolpropane EO-modified (3 mol) triacrylate (M-350: trade name; manufactured by Toagosei Co., Ltd.), trimethylolpropane EO-modified (6 mol) triacrylate (M-360: product) Name: manufactured by Toagosei Co., Ltd.), EO-modified (3 mol) glycerin triacrylate (A-GLY-3E: trade name; manufactured by Shin-Nakamura Chemical Co., Ltd.), EO-modified (9 mol) glycerin triacrylate (A -GLY-9E: commercial name; made by Shin-Nakamura Chemical Co., Ltd.)

  When the content of the (meth) acrylic acid ester (A) represented by the formula (1) in the ink of the present invention is 30 to 70% by weight, it is not only excellent in photocurability but also formed from the ink of the present invention. It is preferable because it has a good balance between the transmittance of the cured film, the adhesion to the substrate, and the strength, more preferably 40 to 65% by weight, still more preferably 45 to 60% by weight, and particularly preferably 50 to 60%. % By weight.

<1.3. Monofunctional (meth) acrylate (B)>
The monofunctional (meth) acrylate (B) does not affect the jetting property and photocurability of the ink of the present invention, and the adhesion, transmittance, and strength of the cured film obtained from the ink, and It is a compound that can lower the viscosity of the ink of the present invention.
Moreover, the adhesiveness, the transmittance | permeability, and intensity | strength with respect to a board | substrate required for the microlens array obtained from this cured film can be maintained by using monofunctional (meth) acrylate (B).

  The monofunctional (meth) acrylate (B) is not particularly limited as long as the above properties are satisfied, but a monofunctional (meth) acrylate having an alkyl moiety is preferable, and more preferably an alkyl moiety having 1 to 6 carbon atoms. Monofunctional (meth) acrylate, more preferably monofunctional (meth) acrylate having an alkyl moiety having 2 to 4 carbon atoms, and particularly preferably monofunctional (meth) having an alkyl moiety having 4 carbon atoms. Acrylate.

  Specific examples of the monofunctional (meth) acrylate (B) include cyclohexyl (meth) acrylate, n-hexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopenta Nyl (meth) acrylate, isobornyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2 -Adamantyl (meth) acrylate, 3,5-dimethyl-7-hydroxyadamantyl (meth) acrylate, 3-hydroxy-1-methacryloxyadamantane, 3-hydroxy-1-adamantyl (meth) acrylate, ethylcyclope Til (meth) acrylate, 3,5-dihydroxy-1-methacryloxyadamantane, methacryloyloxynorbornane methacrylate, tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, N-acryloyloxyethyl hexahydrophthalimide, Cyclic trimethylolpropane formal acrylate, γ-butyrolactone (meth) acrylate, mevalonolactone (meth) acrylate, cyclic imide acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, methylphenoxyethyl (meth) acrylate, 2-phenoxyethyl (Meth) acrylate, 2-phenoxyethyl (meth) acrylate ethylene oxide and / or propylene Lenoxide addition monomer, 4-t-butylcyclohexyl (meth) acrylate, cyclohexyldimethanol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) ) Acrylate, isoamyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, Isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) a Relate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,4-cyclohexanedimethanol mono ( (Meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethoxyethoxyethyl (meth) Acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, dipropylene glycol (meth) acrylate, Tildiglycol (meth) acrylate, glycerol mono (meth) acrylate, trifluoroethyl (meth) acrylate, glycidyl (meth) acrylate, 3,4-epoxycyclohexyl (meth) acrylate, methyl glycidyl (meth) acrylate, 3-methyl -3- (meth) acryloxymethyl oxetane, 3-ethyl-3- (meth) acryloxymethyl oxetane, 3-methyl-3- (meth) acryloxyethyl oxetane, 3-ethyl-3- (meth) acryloxy Ethyl oxetane, p-vinylphenyl-3-ethyloxetane-3-ylmethyl ether, 2-phenyl-3- (meth) acryloxymethyloxetane, 2-trifluoromethyl-3- (meth) acryloxymethyloxetane, 4 -Trifluoromethyl-2 (Meth) acryloxymethyl oxetane, (3-ethyl-3-oxetanyl) methyl (meth) acrylate, ω-carboxypolycaprolactone mono (meth) acrylate, succinic acid mono [2- (meth) acryloyloxyethyl], malee Acid mono [2- (meth) acryloyloxyethyl] and 2- (meth) acryloyloxyethyl acid phosphate, and (meth) acrylic acid.

  Among these, cyclohexyl (meth) acrylate, n-hexyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate, ethyl (meth) acrylate, or methyl (meth) When acrylate is used, the balance of jetting and photocuring properties, and the transmittance of the cured film obtained from the ink, adhesion to the substrate, and high strength are improved. From these viewpoints, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate, and ethyl (meth) acrylate are more preferable, and n-butyl (meth) acrylate and t are more preferable. -Butyl (meth) acrylate.

  The monofunctional (meth) acrylate (B) may be a single compound or a mixture of two or more compounds.

  The content of the monofunctional (meth) acrylate (B) is preferably 20 to 60% by weight of the total amount of the ink of the present invention because the viscosity of the ink can be adjusted according to the intended use. Considering the balance, it is more preferably 25 to 50% by weight, further preferably 30 to 45% by weight, and particularly preferably 30 to 40% by weight.

<1.4. Photoinitiator (C)>
The inkjet ink of the present invention contains a photopolymerization initiator (C). The photopolymerization initiator (C) is not particularly limited as long as it is a compound capable of generating radicals upon irradiation with ultraviolet rays or visible light, but is not limited to an α-hydroxylalkylphenone-based or acylphosphine oxide-based photopolymerization initiator. Among them, acylphosphine oxide compounds are particularly preferable from the viewpoints of photocurability and transmittance of a cured film obtained from the ink.
Further, from the viewpoint of the transmittance of the microlens array obtained from the cured film, acylphosphine oxide compounds are particularly preferable.

Specific examples of the photopolymerization initiator (C) include benzophenone, Michler's ketone, 4,4′-bis (diethylamino) benzophenone, xanthone, thioxanthone, isopropylxanthone, 2,4-diethylthioxanthone, 2-ethylanthraquinone, acetophenone, 2 -Hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-4'-isopropylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, isopropyl benzoin ether, isobutyl benzoin ether, 2,2-diethoxyacetophenone, 2 , 2-dimethoxy-2-phenylacetophenone, camphorquinone, benzanthrone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzi 2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 4,4′-di (t-butylperoxycarbonyl) benzophenone, 3,4,4′-tri (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t -Hexylperoxycarbonyl) benzophenone, 3,3'-di (methoxycarbonyl) -4,4'-di (t-butylperoxycarbonyl) benzophenone, 3,4'-di (methoxycarbonyl) -4,3'-di (T-butylperoxycarbonyl) benzophenone, 4,4′-di (methoxycarbonyl) -3,3′-di (t-butylpe) Ruoxycarbonyl) benzophenone, 2- (4′-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (3 ′, 4′-dimethoxystyryl) -4,6-bis (trichloro) Methyl) -s-triazine, 2- (2 ′, 4′-dimethoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2′-methoxystyryl) -4,6-bis ( Trichloromethyl) -s-triazine, 2- (4′-pentyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 4- [p-N, N-di (ethoxycarbonylmethyl)]- 2,6-di (trichloromethyl) -s-triazine, 1,3-bis (trichloromethyl) -5- (2′-chlorophenyl) -s-triazine, 1,3-bis (trichloromethyl) ) -5- (4′-methoxyphenyl) -s-triazine, 2- (p-dimethylaminostyryl) benzoxazole, 2- (p-dimethylaminostyryl) benzthiazole, 2-mercaptobenzothiazole, 3,3 ′ -Carbonylbis (7-diethylaminocoumarin), 2- (o-chlorophenyl) -4,4 ', 5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis (2-chlorophenyl) -4,4 ', 5,5'-tetrakis (4-ethoxycarbonylphenyl) -1,2'-biimidazole, 2,2'-bis (2,4-dichlorophenyl) -4,4', 5,5 '-Tetraphenyl-1,2'-biimidazole, 2,2'-bis (2,4-dibromophenyl) -4,4', 5,5'-tetraphenyl-1,2'-biimidazole, 2 , 2'-bi (2,4,6-trichlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 3- (2-methyl-2-dimethylaminopropionyl) carbazole, 3, 6-bis (2-methyl-2-morpholinopropionyl) -9-n-dodecylcarbazole, 1-hydroxycyclohexyl phenyl ketone, bis (η ⁵ -2,4-cyclopentadien-1-yl) -bis (2,6 -Difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide Can do.

  Among these, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-4′-isopropylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, bis (2,4,6-trimethylbenzoyl) phenyl More preferred are phosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

  The photopolymerization initiator (C) may be a single compound or a mixture of two or more compounds.

  When the content of the photopolymerization initiator (C) is 1 to 20% by weight of the total amount of the ink of the present invention, the ink of the present invention is particularly excellent in photocurability with respect to ultraviolet rays and can maintain high transmittance. Preferably, it is 2 to 15% by weight, more preferably 3 to 10% by weight.

<1.5. Other ingredients>
The ink-jet ink of the present invention may contain other components such as a phenol resin, a melamine resin, an epoxy resin, an epoxy curing agent, a surfactant, a colorant, and a polymerization inhibitor in order to improve various properties.

(1.5.1. Phenolic resin)
In order to improve the strength of the cured film obtained from the ink, the inkjet ink of the present invention may contain a phenol resin.

  Phenol resins include novolak resins obtained by condensation reaction of aromatic compounds having phenolic hydroxyl groups and aldehydes, vinylphenol homopolymers (including hydrogenated products), and vinylphenols and copolymers with these. Vinylphenol copolymers (including hydrogenated products) with various compounds are preferably used.

  Specific examples of the aromatic compound having a phenolic hydroxyl group include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, and m-butylphenol. P-butylphenol, o-xylenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, 3, 4,5-trimethylphenol, p-phenylphenol, resorcinol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, bisphenol A, bisphenol F, terpene skeleton-containing diphenol, gallic acid, gallic acid ester, α-naphthol and β-naphthol For example.

  Specific examples of aldehydes include formaldehyde, paraformaldehyde, furfural, benzaldehyde, nitrobenzaldehyde and acetaldehyde.

  Specific examples of the compound copolymerizable with vinylphenol include (meth) acrylic acid or a derivative thereof, styrene or a derivative thereof, maleic anhydride, vinyl acetate and acrylonitrile.

  Specific examples of the phenolic resin include Resitop PSM-6200 (manufactured by Gunei Chemical Co., Ltd.), Shonor BRG-555 (manufactured by Showa Polymer Co., Ltd.), Marca Linker MS-2P, Marca Linker CST70 and Marca Linker. PHM-C (manufactured by Maruzen Petrochemical Co., Ltd.).

  The phenol resin used in the ink of the present invention may be a single compound or a mixture of two or more compounds.

  It is preferable that the content of the phenol resin is 0.5 to 20% by weight of the total amount of the ink of the present invention because the strength of the cured film obtained from the ink is improved, and more preferable in consideration of the balance with other characteristics. Is 0.5 to 10% by weight, more preferably 0.5 to 7% by weight.

(1.5.2. Melamine resin)
The inkjet ink of the present invention may contain a melamine resin in order to improve the strength of the cured film obtained from the ink.

  The melamine resin is not particularly limited as long as it is a resin produced by polycondensation of melamine and formaldehyde. Specific examples thereof include methylol melamine, etherified methylol melamine, benzoguanamine, methylol benzoguanamine, etherified methylol benzoguanamine and their condensation. Among them, methylol melamine is preferable.

  Specific examples of commercially available melamine resins include Nicalac MW-30, MW-30HM, MW-390, MW-100LM, MX-750LM (manufactured by Sanwa Chemical Co., Ltd.).

  The melamine resin used in the ink of the present invention may be a single compound or a mixture of two or more compounds.

  When the content of the melamine resin is 0.5 to 20% by weight of the total amount of the ink of the present invention, it is preferable because the strength of the cured film obtained from the ink is improved, and more preferable in consideration of the balance with other characteristics. Is 0.5 to 10% by weight, more preferably 0.5 to 7% by weight.

(1.5.3. Epoxy resin)
The ink jet ink of the present invention may contain an epoxy resin in order to improve the strength of the cured film obtained from the ink.

The epoxy resin is a compound having a structure derived from an epoxide represented by formula (2-1) or formula (2-2) (hereinafter also simply referred to as “epoxy structure”) in one molecule. There is no particular limitation.

  Specific examples of the epoxy resin include, for example, novolak type (phenol novolak type and cresol novolak type), bisphenol A type, bisphenol F type, hydrogenated bisphenol A type, hydrogenated bisphenol F type, bisphenol S type, and trisphenol methane type. , Tetraphenolethane type, bixylenol type, biphenol type, alicyclic and heterocyclic epoxy compounds, and epoxy compounds having dicyclopentadiene skeleton or naphthalene skeleton, preferably novolak type, bisphenol A type and bisphenol F-type epoxy compounds, more preferably bisphenol A-type and bisphenol F-type epoxy compounds among them.

Epoxy resins can be produced by known methods and are also commercially available. Examples of commercially available products include Epicoat 828, 834, 1001, 1004 (manufactured by Japan Epoxy Resin Co., Ltd.), Epicron 840, 850, 1050, 2055, (DIC Corporation), Epototo YD -011, YD-013, YD-127, YD-128 (manufactured by Tohto Kasei Co., Ltd.), D.E.R.317, 331, 661, 664 (Dow Chemical Japan) ), Araldide 6071, 6084, GY250, GY260 (manufactured by Ciba Japan Co., Ltd.), Sumi-Epoxy ESA-011, ESA-014, ELA-115, ELA-128 (Sumitomo Chemical ( E.R. 330, 331, 661, 664 (manufactured by Asahi Kasei E-Materials Co., Ltd.); 152, 154 (manufactured by Japan Epoxy Resin Co., Ltd.), D.E.R.431, 438 (manufactured by Dow Chemical Japan Co., Ltd.), Epicron N-730, N-770, N-865 (DIC) Epototo YDCN-701, YDCN-704 (Toto Kasei Co., Ltd.), Araldide ECN1235, ECN1273, ECN1299 (Ciba Japan Co., Ltd.), XPY307, EPPN-201, EOCN- 1025, EOCN-1020, EOCN-104S, RE-306 (manufactured by Nippon Kayaku Co., Ltd.), Sumi-epoxy ESCN-195X, ESCN-220 (manufactured by Sumitomo Chemical Co., Ltd.), A.E.R. Novolak type epoxy compounds such as ECN-235 and ECN-299 (manufactured by Asahi Kasei E-Materials Co., Ltd.); Epicron 830 (DI Co., Ltd.), JER807 (Japan Epoxy Resin Co., Ltd.), Epototo YDF-170 (Toto Kasei Co., Ltd.), YDF-175, YDF-2001, YDF-2004, Araldide XPY306 (Ciba Japan Co., Ltd.) Bisphenol F type epoxy compounds such as Epototo ST-2004, ST-2007, ST-3000 (manufactured by Tohto Kasei Co., Ltd.), etc .; Celoxide 2021P (Daicel Chemical Industries, Ltd.) Alicyclic epoxy compounds such as Araldide CY175 and CY179 (Ciba Japan); YL-933 (Japan Epoxy Resin), EPPN-501, EPPN-502 (Dow) Trihydroxyphenylmethane type epoxy compounds such as Chemical Japan Products; YL-6056, YX-4000, YL-6121 (manufactured by Japan Epoxy Resin Co., Ltd.) and other bixylenol type or biphenol type epoxy compounds or mixtures thereof; EBPS-200 (manufactured by Nippon Kayaku Co., Ltd.), Bisphenol S type epoxy compounds such as EPX-30 (manufactured by ADEKA) and EXA-1514 (manufactured by DIC);
Bisphenol A novolac type epoxy compound such as JER157S (Japan Epoxy Resin Co., Ltd.); tetraphenylolethane type such as YL-931 (Japan Epoxy Resin Co., Ltd.), Araldide 163 (Ciba Japan Co., Ltd.) Epoxy compounds;
Heterocyclic epoxy compounds such as Araldide PT810 (manufactured by Ciba Japan Co., Ltd.), TEPIC (manufactured by Nissan Chemical Industries, Ltd.); HP-4032, EXA-4750, EXA-4700 (manufactured by DIC Corporation), etc. Examples include naphthalene group-containing epoxy compounds; epoxy compounds having a dicyclopentadiene skeleton such as HP-7200, HP-7200H, and HP-7200HH (manufactured by DIC Corporation); xylylene bisoxetane.

The epoxy resin used in the ink of the present invention may be a single compound or a mixture of two or more compounds.
It is preferable that the content of the epoxy resin is 0.5 to 20% by weight of the total amount of the ink because the strength of the cured film obtained from the ink of the present invention is improved, and more preferably 0.5 to 10% by weight. More preferably, it is 0.5 to 7% by weight.

(1.5.4. Epoxy curing agent)
When the inkjet ink of the present invention contains an epoxy resin, an epoxy curing agent may be further added to improve the strength of the cured film. As the epoxy curing agent, an acid anhydride curing agent, an amine curing agent, a catalytic curing agent, and the like are preferable.

  Specific examples of the acid anhydride curing agent include maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrotrimellitic anhydride, phthalic anhydride, anhydrous Trimellitic acid, pyromellitic anhydride, methyltetrahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, hexachloroendomethylenetetrahydrophthalic anhydride, methyl-3,6-endomethylenetetrahydrophthalic anhydride and styrene A maleic anhydride copolymer is mentioned.

  Specific examples of the amine curing agent include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dicyandiamide, polyamidoamine (polyamide resin), ketimine compound, isophoronediamine, m-xylenediamine, m-phenylenediamine, 1,3- Bis (aminomethyl) cyclohexane, N-aminoethylpiperazine, 4,4′-diaminodiphenylmethane, 4,4′-diamino-3,3′-diethyldiphenylmethane and diaminodiphenylsulfone.

  Specific examples of the catalyst-type curing agent include tertiary amine compounds and imidazole compounds.

  The epoxy curing agent used in the ink of the present invention may be a single compound or a mixture of two or more compounds.

  When the content of the epoxy curing agent is 0.5 to 20% by weight of the total amount of the ink of the present invention, the strength of the cured film obtained from the ink of the present invention is improved, and more preferably 0.5 to 10%. % By weight, more preferably 0.5 to 7% by weight.

(1.5.5. Surfactant)
The inkjet ink of the present invention may contain a surfactant in order to improve, for example, wettability to a base substrate and film surface uniformity of a cured film obtained from the ink. As the surfactant, a silicon surfactant, an acrylic surfactant, a fluorine surfactant, or the like is used.

  Specific examples of the surfactant include silicon surfactants such as Byk-300, 306, 335, 310, 341, 344, and 370 (by Big Chemie Japan Co., Ltd.), Byk- Acrylic surfactants such as 354, 358, and 361 (Bic Chemie Japan Co., Ltd.), DFX-18, Footage 250, or 251 (manufactured by Neos Co., Ltd.) and Megafax F-475, Fluorine-based surfactants such as F-477, F-553, and F-554 (manufactured by DIC Corporation) can be exemplified.

  The surfactant used in the ink of the present invention may be a single compound or a mixture of two or more compounds.

  It is preferable that the surfactant content is 0.001 to 1% by weight of the total amount of the ink of the present invention because the uniformity of the surface of the cured film obtained from the ink is improved, and the balance with other properties is taken into consideration. Then, it is more preferably 0.001 to 0.1% by weight, and still more preferably 0.001 to 0.05% by weight.

(1.5.6. Other compounds having a radical polymerizable double bond)
The inkjet ink of the present invention is not limited to the (meth) acrylic acid ester (A) and monofunctional (meth) acrylate (B) represented by the formula (1). In addition, the compound having another radical polymerizable double bond may be added as long as the adhesiveness, transmittance, and strength of the cured film obtained from the ink are not impaired.

  Specific examples of compounds having other radical polymerizable double bonds include bis (hydroxymethyl) tricyclodecane di (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, bisphenol F EO modified di (meth). Acrylate, bisphenol A EO modified di (meth) acrylate, polypropylene glycol di (meth) acrylate, isocyanuric acid EO modified di and tri (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, Ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanedi Di (meth) acrylate, neopentyl glycol di (meth) acrylate, or trimethylolpropane trioxyethyl (meth) acrylate, (meth) acrylic acid dimer, crotonic acid, α-chloroacrylic acid, cinnamic acid, maleic acid, Fumaric acid, N-vinylformamide, and polymethyl methacrylate macromonomer, N-cyclohexylmaleimide, N-phenylmaleimide, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide may be mentioned.

  The other compound having a radical polymerizable double bond used in the ink of the present invention may be a single compound or a mixture of two or more compounds.

  When the content of the other compound having a radical polymerizable double bond is 0.1 to 20% by weight of the total amount of the ink of the present invention, the photocurability, the adhesion of the cured film to the substrate, the transmittance, and the strength It is preferable because the balance is good, more preferably 0.1 to 10% by weight, still more preferably 0.1 to 5% by weight.

(1.5.7. Solvent)
The inkjet ink of the present invention is added with a solvent within a range that does not impair the jetting and photocuring properties of the ink of the present invention and the adhesion, transmittance, and strength of the cured film obtained from the ink. May be.

As a solvent that can be used in the present invention, a solvent having a boiling point higher than the temperature at which the inkjet head is heated, more specifically, a solvent having a boiling point of 100 to 300 ° C. is preferable from the viewpoint of jetting characteristics. When heating an inkjet head to high temperature (for example, 70-120 degreeC), the solvent whose boiling point is 200-300 degreeC is preferable.
However, when heating the ink jet head, it is basically preferable not to include a solvent in the ink of the present invention.

  Specific examples of the solvent having a boiling point of 100 to 300 ° C. include butyl acetate, butyl propionate, ethyl lactate, methyl oxyacetate, ethyl oxyacetate, butyl oxyacetate, methyl methoxyacetate, ethyl methoxyacetate, butyl methoxyacetate, ethoxy Methyl acetate, ethyl ethoxyacetate, methyl 3-oxypropionate, ethyl 3-oxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, 2 -Methyl oxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, methyl 2-ethoxypropionate, 2- Et Ethyl cypropionate, methyl 2-oxy-2-methylpropionate, ethyl 2-oxy-2-methylpropionate, methyl 2-methoxy-2-methylpropionate, ethyl 2-ethoxy-2-methylpropionate, pyrubin Methyl acetate, ethyl pyruvate, propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl 2-oxobutanoate, ethyl 2-oxobutanoate, dioxane, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tri Propylene glycol, 1,4-butanediol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl Ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether acetate, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether Acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol Examples include recall methyl ethyl ether, toluene, xylene, anisole, γ-butyrolactone, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and dimethylimidazolidinone.

  The solvent used in the ink of the present invention may be a single compound or a mixture of two or more compounds.

  It is preferable that the content of the solvent is 0.1 to 20% by weight of the total amount of the ink of the present invention because the nozzle is difficult to dry during jetting. Considering the balance with other characteristics, it is more preferably 0.1 to 10% by weight, and further preferably 0.1 to 5% by weight.

(1.5.8. Polymerization inhibitor)
The inkjet ink of the present invention may contain a polymerization inhibitor in order to improve storage stability. Specific examples of the polymerization inhibitor include 4-methoxyphenol, hydroquinone and phenothiazine. Among these, phenothiazine is preferable because the change (increase) in the viscosity of the ink is small even during long-term storage.

  The polymerization inhibitor used in the ink of the present invention may be a single compound or a mixture of two or more compounds.

  It is preferable that the content of the polymerization inhibitor is 0.01 to 1% by weight of the total amount of the ink of the present invention because the change in viscosity is small even during long-term storage, and more preferable in consideration of the balance with other characteristics. Is 0.01 to 0.5% by weight, more preferably 0.01 to 0.1% by weight.

<1.6. Method for Preparing Photocurable Ink for Ink of the Present Invention>
The ink-jet ink of the present invention can be prepared by mixing each component as a raw material by a known method.
In particular, the ink of the present invention is preferably prepared by mixing the components (A) to (C) and other components as necessary, and filtering and degassing the resulting solution. The ink of the present invention thus prepared is excellent in jetting properties. For the filtration, for example, a fluororesin membrane filter is used.

<1.7. Storage of Inkjet Ink of the Present Invention>
When the ink-jet ink of the present invention is stored at -20 to 25 ° C, the viscosity change (increase) during storage is small, and the storage stability is good.

[2. Application of inkjet ink by inkjet method]
The inkjet ink of the present invention can be applied using a known inkjet application method. As an inkjet coating method, for example, a method in which mechanical energy is applied to ink to eject (apply) the ink from an inkjet head (so-called piezo method), and a coating method in which thermal energy is applied to ink to apply the ink (so-called piezo method) So-called bubble jet (registered trademark) system.

  By using the inkjet coating method, the inkjet ink can be applied in a predetermined pattern.

  As an inkjet head, what has the heat generating part liquid contact surface containing a metal and / or a metal oxide is mentioned, for example. Specific examples of the metal and / or metal oxide include metals such as Ta, Zr, Ti, Ni, and Al, and oxides of these metals.

  As a preferable coating apparatus for performing coating using the ink of the present invention, for example, energy corresponding to a coating signal is given to ink in a room of an ink jet head having an ink storage section in which ink is stored, and the energy An apparatus that performs application (drawing) corresponding to the application signal while generating ink droplets can be used.

  The ink jet coating apparatus is not limited to one in which the ink jet head and the ink container are separated, and may be one in which they are integrated so as not to be separated. The ink container is integrated with the ink jet head in a separable or non-separable manner and mounted on the carriage, and is provided at a fixed portion of the apparatus so that the ink is supplied to the ink jet head through an ink supply member, for example, a tube. It may be in the form of supplying.

  As described above, the heating temperature of the ink jet head is preferably 40 to 120 ° C., and the viscosity of the ink of the present invention at the heating temperature is preferably 1 to 30 mPa · s.

[3. Formation of cured film]
The cured film of the present invention can be obtained by applying the ink jet ink of the present invention described above to the substrate surface by an ink jet method, and then irradiating the ink with light such as ultraviolet rays or visible light to cure the coating film.

When irradiating ultraviolet rays or visible light, etc., the amount of exposure to be irradiated depends on the composition of the ink, but is measured with an integrating light meter UIT-201 equipped with a photoreceiver UVD-365PD manufactured by USHIO INC. preferably about 100~5,000mJ / cm ^2, more preferably about 200~4000mJ / cm ^2, about 300~3000mJ / cm ² is more preferred. Moreover, 200-500 nm is preferable and, as for wavelengths, such as an ultraviolet-ray and visible light to irradiate, 300-450 nm is more preferable.
In addition, the UV exposure amount described below is a value measured by an integrating light meter UIT-201 equipped with a photoreceiver UVD-365PD manufactured by USHIO INC.

  The exposure apparatus is not particularly limited as long as it is an apparatus that mounts a high-pressure mercury lamp lamp, an ultra-high pressure mercury lamp lamp, a metal halide lamp, a halogen lamp, or the like and irradiates ultraviolet rays or visible rays in the range of 250 to 500 nm.

  In addition, if necessary, the cured film cured by light irradiation may be further heated and baked, and the cured film is cured more firmly by heating and baking at 80 to 250 ° C. for 10 to 60 minutes. Can be made.

  The “substrate” to which the ink of the present invention is applied, which can be used in the present invention, is not particularly limited as long as it can be a target to which the ink of the present invention is applied, and the shape is not limited to a flat plate shape, but a curved surface shape. It may be.

  The material of the substrate is not particularly limited. For example, polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride, fluorine resin, acrylic resin, Plastic films such as polyamide, polycarbonate and polyimide, cellophane, acetate, metal foil, laminated film of polyimide and metal foil, glassine paper, parchment paper with sealing effect, polyethylene, clay binder, polyvinyl alcohol, starch or carboxy Mention may be made of paper and glass treated with methylcellulose (CMC) or the like.

  The substances constituting these substrates may further include an antioxidant, a deterioration inhibitor, a filler, an ultraviolet absorber, an antistatic agent and / or an electromagnetic wave preventing agent as long as the effects of the present invention are not adversely affected. An additive may be contained. Also, part of the surface of the substrate may be subjected to easy adhesion treatment such as water repellent treatment, corona treatment, plasma treatment, or blast treatment if necessary, or the surface may be subjected to an easy adhesion layer, a color filter protective film, or a hard coat film. May be provided.

  Although the thickness of a board | substrate is not specifically limited, Usually, it is about 10 micrometers-2 mm, Although it adjusts suitably by the objective to use, 15 micrometers-1.5 mm are preferable, and 20 micrometers-1 mm are more preferable.

  The use of the substrate is not particularly limited, but the cured film obtained from the ink-jet ink of the present invention has excellent adhesion to the substrate, and exhibits high transmittance and high strength. It is preferable to use for manufacture of this.

  The dot diameter of the cured film of the present invention that functions as a microlens array used in such a backlight device is not particularly limited, but is preferably 10 to 100 μm, more preferably 20 to 60 μm, and particularly preferably 30 to 50 μm. preferable. Moreover, although it does not specifically limit also about the height of a dot, Usually, 0.5-10 micrometers is preferable, 1-8 micrometers is more preferable, and 2-6 micrometers is especially preferable.

  By mounting the backlight manufactured using the cured film of the present invention as described above, for example, a liquid crystal display for a liquid crystal display element can be manufactured.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited by these.

<Preparation of inkjet ink and production of cured film pattern formation substrate>
First, the inkjet ink according to Examples 1 to 6 and Comparative Examples 1 to 4 and the cured film pattern forming substrate obtained therefrom will be described.

[Example 1]
As the (meth) acrylic acid ester (A) represented by the formula (1), A-GLY-3E (manufactured by Shin-Nakamura Chemical Co., Ltd.) which is EO-modified (3 mol) glycerin triacrylate, and monofunctional (meta ) N-butyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) as acrylate (B), and DAROCUR TPO (trade name; 2,4,6-trimethylbenzoyldiphenylphosphine oxide) as photopolymerization initiator (C). Ciba Japan Co., Ltd.) and phenothiazine (manufactured by Tokyo Chemical Industry Co., Ltd.) as a polymerization inhibitor were mixed and dissolved in the following composition ratios, filtered through a 1 μm PTFE membrane filter, and used for inkjet. Ink 1 was prepared.
(A) A-GLY-3E 350.00 g
(B) n-butyl methacrylate 200.00 g
(C) DAROCUR TPO 55.00g
(Others) Phenothiazine 0.28g
It was 12 mPa · s as a result of measuring the viscosity of ink-jet ink 1 at 25 ° C. using an E-type viscometer (TV-22 manufactured by Toki Sangyo Co., Ltd., hereinafter the same).

  Prepare two 4 cm square glass substrates (thickness: 0.7 mm), inject the inkjet ink 1 into the inkjet cartridge, and attach it to an inkjet apparatus (DMP-2831 manufactured by FUJIFILM Dimatix Inc.). A dot pattern with a design value of 40 μm in diameter is drawn on one glass substrate under the discharge conditions (piezo voltage) 16 V, head temperature 30 ° C., drive frequency 5 kHz, and the number of times of application once. A square pattern with a 3 cm piece was drawn in the center on the other glass substrate.

Two substrates on which a dot pattern and a square pattern are drawn using ink-jet ink 1 are irradiated with ultraviolet rays at a UV exposure amount of 2000 mJ / cm ² using a UV irradiation device (J-CURE 1500 manufactured by JATEC Corporation). As a result, a substrate 1a on which dots having a dot diameter of 40 μm and a height of 5.0 μm were formed and a substrate 1b on which a square pattern having a piece of 3 cm and a thickness of 5.0 μm was formed were obtained.

[Example 2]
M-350 (manufactured by Toagosei Co., Ltd.), which is trimethylolpropane EO-modified (3 mol) triacrylate, was used as the (meth) acrylic acid ester (A) represented by the formula (1), with the following composition ratios. Except for the above, ink jet ink 2 was prepared in the same manner as Example 1.
(A) M-350 350.00 g
(B) n-butyl methacrylate 200.00 g
(C) DAROCUR TPO 55.00g
(Others) Phenothiazine 0.28g
As a result of measuring the viscosity of the inkjet ink 2 at 25 ° C. using an E-type viscometer, it was 10 mPa · s.

  A substrate 2a on which a dot pattern with a dot diameter of 40 μm and a height of 4.9 μm was formed, and a square pattern with a piece of 3 cm and a thickness of 4.8 μm was formed using the ink-jet ink 2 in the same manner as in Example 1. A substrate 2b was obtained.

[Example 3]
Inkjet ink 3 was prepared in the same manner as in Example 1 except that ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the monofunctional (meth) acrylate (B) and the following composition ratio was used.
(A) A-GLY-3E 350.00 g
(B) Ethyl methacrylate 200.00g
(C) DAROCUR TPO 55.00g
(Others) Phenothiazine 0.28g
As a result of measuring the viscosity of the ink-jet ink 3 at 25 ° C. using an E-type viscometer, it was 9 mPa · s.

  A substrate 3a on which a dot pattern with a dot diameter of 39 μm and a height of 4.8 μm was formed and a square pattern with a piece of 3 cm and a thickness of 4.8 μm were formed using the ink-jet ink 3 in the same manner as in Example 1. A substrate 3b was obtained.

[Example 4]
Inkjet ink 4 was prepared in the same manner as in Example 1 except that n-hexyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the monofunctional (meth) acrylate (B) and the following composition ratio was used.
(A) A-GLY-3E 350.00 g
(B) n-hexyl methacrylate 200.00 g
(C) DAROCUR TPO 55.00g
(Others) Phenothiazine 0.28g
As a result of measuring the viscosity of the ink-jet ink 4 at 25 ° C. using an E-type viscometer, it was 14 mPa · s.

  A substrate 4a on which a dot pattern with a dot diameter of 41 μm and a height of 5.1 μm was formed, and a square pattern with a piece of 3 cm and a thickness of 5.1 μm were formed using the inkjet ink 4 in the same manner as in Example 1. A substrate 4b was obtained.

[Example 5]
An inkjet ink 5 was prepared in the same manner as in Example 1 except that A-GLY-3E, which is the (meth) acrylic ester (A) represented by the formula (1), was increased to the following composition ratio. did.
(A) A-GLY-3E 600.00 g
(B) n-butyl methacrylate 200.00 g
(C) DAROCUR TPO 80.00g
(Other) Phenothiazine 0.40g
As a result of measuring the viscosity of the ink-jet ink 5 at 25 ° C. using an E-type viscometer, it was 87 mPa · s.

  A substrate 5a on which a dot pattern having a dot diameter of 40 μm and a height of 5.3 μm was formed in the same manner as in Example 1 except that the inkjet head 5 was used and the head temperature was set to 70 ° C. A substrate 5b on which a 3 μm square pattern was formed was obtained.

[Example 6]
A-GLY-3E which is (meth) acrylic acid ester (A) represented by the formula (1) is reduced, and M-309 which is trimethylolpropane triacrylate as another component instead (Toagosei Co., Ltd.) Ink jet ink 6 was prepared in the same manner as in Example 1 except that the following composition ratio was added.
(A) A-GLY-3E 200.00 g
(Others) M-309 150.00g
(B) n-butyl methacrylate 200.00 g
(C) DAROCUR TPO 55.00g
(Others) Phenothiazine 0.28g
As a result of measuring the viscosity of the inkjet ink 6 at 25 ° C. using an E-type viscometer, it was 10 mPa · s.

  A substrate 6a on which a dot pattern with a dot diameter of 40 μm and a height of 4.9 μm was formed, and a square pattern with a piece of 3 cm and a thickness of 5.0 μm was formed in the same manner as in Example 1 using the inkjet ink 6. A substrate 6b was obtained.

[Comparative Example 1]
A-GLY-3E which is (meth) acrylic acid ester (A) represented by formula (1) is further reduced, and M-309 which is trimethylolpropane triacrylate as another component is added instead. Inkjet ink 7 was prepared in the same manner as in Example 1 except that the composition ratio was changed.
(A) A-GLY-3E 100.00 g
(Others) M-309 250.00g
(B) n-butyl methacrylate 200.00 g
(C) DAROCUR TPO 55.00g
(Others) Phenothiazine 0.28g
As a result of measuring the viscosity of the ink-jet ink 7 at 25 ° C. using an E-type viscometer, it was 10 mPa · s.

  A substrate 7a on which a dot pattern having a dot diameter of 40 μm and a height of 4.9 μm was formed and a square pattern having a thickness of 3 cm and a thickness of 5.0 μm were formed by using the inkjet ink 7 in the same manner as in Example 1. A substrate 7b was obtained.

[Comparative Example 2]
Example 1 except that M-309, which is trimethylolpropane triacrylate as another component, was added in place of the (meth) acrylic acid ester (A) represented by the formula (1) to obtain the following composition ratio. In the same manner, inkjet ink 8 was prepared.
(Others) M-309 350.00g
(B) n-butyl methacrylate 200.00 g
(C) DAROCUR TPO 55.00g
(Others) Phenothiazine 0.28g
As a result of measuring the viscosity of the ink-jet ink 8 at 25 ° C. using an E-type viscometer, it was 9 mPa · s.

  A substrate 8a on which a dot pattern having a dot diameter of 39 μm and a height of 4.8 μm was formed, and a square pattern having a thickness of 3 cm and a thickness of 4.9 μm was formed using the inkjet ink 8 in the same manner as in Example 1. A substrate 8b was obtained.

[Comparative Example 3]
Instead of the (meth) acrylic acid ester (A) represented by the formula (1), SR-9003 (manufactured by Sartomer Japan), which is a propylene oxide-modified neopentyl diacrylate as another component, is added and An inkjet ink 9 was prepared in the same manner as in Example 1 except that the composition ratio was changed.
(Others) SR-9003 600.00g
(B) n-butyl methacrylate 200.00 g
(C) DAROCUR TPO 60.00g
(Others) Phenothiazine 0.30g
As a result of measuring the viscosity of the inkjet ink 9 at 25 ° C. using an E-type viscometer, it was 6 mPa · s.

  An attempt was made to produce a patterned substrate using the inkjet ink 9 in the same manner as in Example 1. However, a dot pattern and a cured film could not be obtained due to poor curability.

[Comparative Example 4]
SR which is propylene oxide modified neopentyl diacrylate of A-GLY-3E which is (meth) acrylic acid ester (A) represented by formula (1), monofunctional (meth) acrylate (B), and other components Inkjet ink 10 was prepared in the same manner as in Example 1 except that −9003 was added to obtain the following composition ratio.
(A) A-GLY-3E 200.00 g
(Others) SR-9003 200.00g
(B) n-butyl methacrylate 100.00 g
(C) DAROCUR TPO 50.00g
(Others) Phenothiazine 0.25g
As a result of measuring the viscosity of the inkjet ink 10 at 25 ° C. using an E-type viscometer, it was 13 mPa · s.

  A substrate 10a on which a dot pattern having a dot diameter of 40 μm and a height of 5.1 μm was formed and a square pattern having a thickness of 3 μm and a thickness of 5.2 μm were formed using the inkjet ink 10 in the same manner as in Example 1. A substrate 10b was obtained.

<Evaluation of inkjet ink and patterned cured film>
Subsequently, the jetting properties, the photocurability, the adhesion of the cured film to the substrate, the transmittance of the cured film, and the strength of the inkjet ink obtained above were evaluated. Each test method is as follows, and the evaluation results are shown in Tables 1 and 2.

(Ink jetting test)
The dot pattern on the substrates (1a to 10a, 1b to 10b) obtained in each of the examples and comparative examples, and the 3 cm square square pattern disturbance and printing fading were observed to evaluate the ink jetting properties. did. The evaluation criteria are as follows.
○: No pattern disturbance or print fading at all Δ: Pattern disorder or print faint many ×: Ink cannot be ejected (that is, pattern cannot be formed).

(Photocurability test)
The surface of the square pattern substrate (1b to 10b) of 3 cm square obtained in each Example and Comparative Example was touched, and the surface state of the cured film was observed with a microscope. The evaluation criteria are as follows.
○: No finger marks remain on the surface of the cured film.
Δ: Slight finger marks remain on the surface of the cured film.
X: The finger touch remains completely on the surface of the cured film.

(Measurement of transmittance of cured film)
Using a transmittance measuring device V-670 (manufactured by JEOL Ltd.), the transmittance at a wavelength of 400 nm was measured using a 3 cm square square pattern substrate (1b to 10b) obtained in each example and comparative example. did. As a reference, a 4 cm square glass substrate (thickness: 0.7 mm) on which no cured film was formed was used.

(Adhesion test of cured film to substrate)
Adhesive tape (Sumitomo 3M Co., Ltd. “Polyester tape No. 56: Adhesive strength; 5.5 N / cm”) was applied to the dot pattern substrates (1a to 10a) obtained in each Example and Comparative Example, and then The adhesion of the cured film to the substrate was evaluated by observing the state of the dot pattern remaining on the substrate when peeled. The evaluation criteria are as follows.
○: No change in dot pattern △: Some dots were peeled ×: All dots were peeled

(Strength measurement)
Using the 3 cm square square pattern substrates (1b to 10b) obtained in each of Examples and Comparative Examples, the pencil hardness was measured according to JIS 5400, and the strength was examined.

The above evaluation results are shown in Tables 1 and 2 below.

  As is apparent from the results shown in Table 1, the substrates 1a to 10a and 1b to 10b obtained using the ink-jet ink according to the present invention do not show pattern disturbance or print blurring, and have jetting characteristics. Was good.

  Subsequently, when the photocurability of the ink was evaluated in the substrates 1b to 10b, all the substrates other than the substrate 9b out of the evaluated substrates were satisfactory with no finger marks remaining on the surface of the cured film. .

  On the other hand, in the substrate 9b, finger touch marks were completely left on the surface of the cured film and the curability was poor, so the subsequent test was interrupted.

  Moreover, when the transmittance | permeability of a 400-nm light beam was measured using the board | substrates 1b-8b and 10b, the transmittance | permeability was high in order of the board | substrate 1b> board | substrate 3b> board | substrate 4b> board | substrate 10b> board | substrate 2b> board | substrate 6b. On the other hand, the transmittance of the substrates 7b and 8b was as low as 96% or less.

  Furthermore, when the adhesiveness of the cured film was evaluated using the substrates 1a to 8a and 10a, the dot patterns of the substrates 1a to 6a and 10a were not changed at all, and the adhesiveness was good. On the other hand, in the substrates 7a to 8a, some of the dots were peeled off, and the adhesion was reduced.

  Finally, when the strength was measured using the substrates 1b to 8b and 10b, the cured films of the substrates 1b to 8b exhibited 3H pencil hardness. On the other hand, the cured film of the substrate 10b exhibited a pencil hardness of H, and the strength was low.

  As described above, according to the present invention, an ink jet that is excellent in ink jetting property, photocurability, adhesion of a cured film to a substrate, and can form a cured film exhibiting high transmittance and high strength. Can be obtained, and can be suitably used for producing optical devices such as liquid crystal displays and display panels.

Claims (13)

A photocurable inkjet ink containing a (meth) acrylic acid ester (A) represented by formula (1), a monofunctional (meth) acrylate (B), and a photopolymerization initiator (C), A photocurable inkjet ink in which a cured film (film thickness: 5 μm) obtained from the ink has a transmittance of 96% or more at 400 nm.

(In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or alkyl having 1 to 6 carbon atoms, and R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently carbon number. Is alkylene of 1-6, k is 0 or 1, and l, m, and n are each independently an integer of 1-10.)   30 to 70% by weight of the (meth) acrylic acid ester (A) represented by the formula (1), 20 to 60% by weight of the monofunctional (meth) acrylate (B) based on the total weight of the ink, and photopolymerization starts The inkjet ink according to claim 1, comprising 1 to 20% by weight of the agent (C). The inkjet ink according to claim 1 or 2, wherein in the formula (1), R ⁵ , R ⁶ and R ⁷ are each independently alkylene having 2 or 3 carbon atoms. The inkjet ink according to claim 1, wherein in formula (1), R ¹ is hydrogen and k is 0.   The inkjet ink according to claim 1, wherein in formula (1), l, m, and n are 1.   The inkjet ink according to any one of claims 1 to 5, wherein the monofunctional (meth) acrylate (B) is a monofunctional (meth) acrylate having an alkyl having 1 to 6 carbon atoms.   Monofunctional (meth) acrylate (B) is cyclohexyl (meth) acrylate, n-hexyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate, ethyl (meth) The inkjet ink according to any one of claims 1 to 6, which is at least one selected from the group consisting of acrylate) and methyl (meth) acrylate.   The inkjet ink according to any one of claims 1 to 7, wherein the photopolymerization initiator (C) is an α-hydroxylalkylphenone-based or acylphosphine oxide-based photopolymerization initiator.   Furthermore, the inkjet ink in any one of Claims 1-8 containing a polymerization inhibitor.   Ethylene oxide modified glycerin triacrylate (ethylene oxide modified: 3 mol) as (meth) acrylic acid ester (A) represented by formula (1), n-butyl (meth) acrylate as monofunctional (meth) acrylate (B) The inkjet ink according to claim 9, further comprising 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator (C) and phenothiazine as a polymerization inhibitor.   The cured film obtained by hardening the ink for inkjets in any one of Claims 1-10.   A microlens array obtained from the cured film according to claim 11.   An optical apparatus comprising the microlens array according to claim 12.