TWI461446B - Ink for in inkjet - Google Patents

Description

Inkjet ink

The present invention relates to an inkjet ink suitable for use in the manufacture of optical devices such as liquid crystal displays or display panels. More specifically, the present invention relates to an inkjet ink suitable for use in a microlens array or the like used in a backlight device.

Conventionally, a liquid crystal display element such as a liquid crystal display has used a transmissive or semi-transmissive liquid crystal display (LCD) which is displayed by using backlight light. Such a transmissive or semi-transmissive LCD is formed by providing an opening in a reflecting plate inside the LCD, and transmitting the backlight light from the opening. In this way, a light guide plate in which a microlens array is disposed between a liquid crystal display panel and a backlight in order to eliminate luminance unevenness is proposed (for example, Japanese Laid-Open Patent Publication No. 2003-107505 (Patent Document 1) )).

Conventionally, in the injection molding method performed as a method of manufacturing such a light guide plate, it is necessary to produce a plurality of molds, which requires a large amount of time and cost. Further, in the case of production by the above-described production method, the patterning accuracy of the resin lens is poor, and luminance unevenness is likely to occur.

In order to solve such problems, a method of forming a microlens array by directly applying a photosensitive material to a substrate by an inkjet method has been developed in recent years (for example, Japanese Patent Laid-Open No. Hei 5-303017 (Patent Document 2), Japanese Patent No. JP-A-2000-180605 (Patent Document 3) and JP-A-2004-240294 (Patent Document 4)). In this way, the method of manufacturing a resin lens using an inkjet method can easily control the pattern by using electronic data such as a personal computer without forming a mold as in the prior art. Therefore, it is possible to suppress the manufacturing cost and the like in a small number of varieties. It is expected to be.

In addition, various ink compositions have been proposed as the photosensitive material for the inkjet method (for example, Japanese Patent Laid-Open Publication No. 2004-117955 (Patent Document 5), Japanese Patent Laid-Open No. Hei No. 2005-340467 (Patent Document 6) Japanese Patent Laid-Open No. 2006-208734 (Patent Document 7) and Japanese Patent Laid-Open No. 2007-24970 (Patent Document 8)), but the microlens array formed of the inks does not have sufficient light. Performance of all properties such as hardenability, adhesion to the substrate, high transmittance, and high strength.

On the other hand, various types of inks have been proposed as photosensitive materials having excellent light-curing properties and adhesion to substrates (for example, Japanese Patent Laid-Open No. Hei 2-6562 (Patent Document 9), Japanese Patent Laid-Open No. Hei 7-53895 Japanese Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. Japanese Patent Publication No. 2007-231231 (Patent Document 15) and Japanese Patent Laid-Open No. 2007-231233 (Patent Document 16)).

However, Japanese Patent Laid-Open No. Hei 2-6562 (Patent Document No. 9), Japanese Patent Laid-Open No. Hei 7-53895 (Patent Document No. 10), and Japanese Patent Laid-Open No. Hei 7-70472 (Patent Document 11) The cured film has a high transmittance but does not have sufficient strength.

In addition, Japanese Patent Laid-Open Publication No. 2003-192943 (Patent Document 12), Japanese Patent Laid-Open No. Hei. No. 2005-162882 (Patent Document 13), WO2006-129530 (Patent Document 14), and Japanese Patent Laid-Open No. 2007-231231 It is estimated that a coloring agent such as a dye or a pigment is added to any of the compositions, and the transmittance is low, and even if it is used, it is estimated that the coloring agent is used in any one of the compositions (Patent Document No. JP-A-2007-231233). The composition of the example in which no colorant is added has a low transmittance and does not have sufficient performance.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-107505

[Patent Document 2] Japanese Patent Laid-Open No. Hei 5-303017

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2000-180605

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2004-240294

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2004-117955

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2005-340467

[Patent Document 7] Japanese Patent Laid-Open Publication No. 2006-208734

[Patent Document 8] Japanese Patent Laid-Open Publication No. 2007-24970

[Patent Document 9] Japanese Patent Laid-Open No. Hei 2-6562

[Patent Document 10] Japanese Patent Laid-Open No. Hei 7-53895

[Patent Document 11] Japanese Patent Laid-Open No. Hei 7-70472

[Patent Document 12] Japanese Patent Laid-Open Publication No. 2003-192943

[Patent Document 13] Japanese Patent Laid-Open Publication No. 2005-162882

[Patent Document 14] International Publication No. 2006-129530

[Patent Document 15] Japanese Patent Laid-Open Publication No. 2007-231231

[Patent Document 16] Japanese Patent Laid-Open Publication No. 2007-231233

Under the circumstances described above, an object of the present invention is to provide an inkjet ink which is excellent in photocurability and excellent in adhesion to a substrate, and which can form a microlens array which exhibits high transmittance and high strength.

The present inventors have found that a photocurable inkjet ink containing a (meth) acrylate, a monofunctional (meth) acrylate, and a photopolymerization initiator represented by the formula (1) is photocurable, and The substrate is excellent in adhesion, and a microlens array exhibiting high transmittance and high strength can be formed, and the present invention has been completed based on this knowledge. Further, the present invention provides a use of a microlens array obtained by such an inkjet ink and a microlens array thereof.

That is, the present invention includes the following items.

[1] A photocurable inkjet ink comprising (meth) acrylate (A) represented by formula (1), a monofunctional (meth) acrylate (B), and a photopolymerization initiator ( C), the transmittance of the cured film (film thickness: 5 μm) obtained from the ink at a light wavelength of 400 nm is 96% or more,

(wherein R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms; and R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a carbon number of 1 The alkyl group of ～6, k is 0 or 1, and l, m and n are each independently an integer of from 1 to 10).

[2] The ink for inkjet according to [1], wherein the ink for inkjet contains 30% by weight (% by weight) to 70% by weight of (methyl) represented by the formula (1) with respect to the total weight of the ink. ) acrylate (A), 20 wt% to 60 wt% of a monofunctional (meth) acrylate (B), and 1 wt% to 20 wt% of a photopolymerization initiator (C).

[3] The ink for inkjet according to [1], wherein, in the formula (1), R ⁵ , R ⁶ and R ⁷ are an alkylene group having a carbon number of 2 or 3, respectively.

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

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

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

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

The inkjet ink according to any one of [1] to [7] wherein the photopolymerization initiator (C) is an α-hydroxyl alkylphenone system, or Acyl phosphine oxide is a photopolymerization initiator.

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

[10] The ink for inkjet according to [9], which comprises an ethylene oxide-modified glycerin triacrylate (ethylene oxide) as the (meth) acrylate (A) represented by the formula (1). Modification: 3 moles), n-butyl (meth)acrylate as monofunctional (meth) acrylate (B), 2,4,6-trimethylbenzene as photopolymerization initiator (C) 2,4,6-trimethyl benzoyl diphenyl phosphine oxide, 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 by the cured film according to [11].

[13] An optical machine comprising the microlens array according to [12].

[Effects of the Invention]

The inkjet ink of the present invention is excellent in ejectability and photocurability of the coating film of the ink, and 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.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

[1. Inkjet ink of the present invention]

The inkjet ink of the present invention (hereinafter also referred to simply as "the ink of the present invention") contains (meth) acrylate (A) represented by the formula (1) in an amount of 30% by weight to 70% by weight based on the total weight of the ink. a photo-curable spray of a monofunctional (meth) acrylate (B) in an amount of from 20% by weight to 60% by weight based on the total weight of the ink, and a photopolymerization initiator (C) in an amount of from 1% by weight to 20% by weight based on the total weight of the ink Ink ink was applied by ink-jet coating the photocurable inkjet ink to a central portion of a glass substrate of 4 cm square to form a square coating film of 3 cm square, and the coating film was cured by light. The transmittance of the obtained glass substrate of the cured film (film thickness: 5 μm) at a light wavelength of 400 nm was 96% or more.

(wherein R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms; and R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a carbon number of 1 ~6 alkylene, k is 0 or 1, l, m and n are each independently an integer from 1 to 10.)

The ink of the present invention may be colorless or colored. From the viewpoint of the transmittance, the ink of the present invention is preferably colorless, and may contain a colored compound in a range that does not impair the effects of the invention. Further, for example, when the state of the cured film is inspected, a coloring agent may be contained in order to facilitate the discrimination between the cured film and the substrate.

In the present specification, "(meth) acrylate" is used to mean either or both of an acrylate and a methacrylate.

Further, the ink of the present invention may contain a phenol resin, a melamine resin, an epoxy resin, an epoxy curing agent, or a surface active agent as needed. Other compounds having a radical polymerizable double bond, a solvent, a polymerization inhibitor, and the like. Here, the "other compound having a radical polymerizable double bond" means a compound other than the (meth) acrylate (A) represented by the formula (1) and the monofunctional (meth) acrylate (B). .

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 inkjet ink of the present invention preferably has a viscosity at 25 ° C as measured by an E-type viscosity meter of 200 mPa ̇s or less, and more preferably 1 mPa ̇ s to 200 mPa ̇ s. When the viscosity is 1 mPa ̇ s to 200 mPa ̇ s, the ejection characteristics by the ink jet apparatus become good. The viscosity of the ink of the invention at 25 ° C is particularly preferably from 2 mPa ‧ to 150 mPa ‧ , particularly preferably from 3 mPa ‧ to 100 mPa ‧ s.

Further, the viscosity of the ink of the present invention at a temperature at which the inkjet coating device is ejected (preferably 10 to 120 ° C) is preferably 1 mPa ‧ to 30 mPa ‧ , more preferably 2 mPa ‧ s 25 mPa‧s, especially 3 mPa‧s to 20 mPa‧s.

When the ink having a viscosity of more than 30 mPa ‧ at 25 ° C is used, the viscosity of the ink at the time of ejection can be lowered by heating the ink jet head, and the ink can be ejected more stably. In the case where the ink jet head is heated and sprayed, the viscosity of the ink for inkjet at a heating temperature (preferably 40 ° C to 120 ° C) is preferably 1 mPa ‧ to 30 mPa ‧ , particularly preferably 2 mPa ‧s to 25 mPa‧s, especially 3 mPa‧s to 20 mPa‧s.

In the case of heating the ink jet head, it is preferred to use a solvent-free ink.

<1.2. (Meth)acrylate (A) represented by the formula (1)>

The ink of the present invention is excellent in photocurability by using the (meth) acrylate (A) represented by the formula (1). The cured film formed of the ink of the present invention is excellent not only in adhesion to the substrate but also in high transmittance and high strength. Further, the microlens array obtained from the cured film is excellent not only in adhesion to the substrate but also in high transmittance and high strength.

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

Wherein, in particular when R ¹ is hydrogen, CH _3, or CH ₂ CH _3, and k is 0, since the light-curable ink of the present invention is good, and the resulting cured film exhibits a high transmittance, high strength, and therefore more good. Further, when R ¹ is hydrogen, the transmittance of the cured film becomes higher, which is preferable. From the viewpoint of photocurability, R ² , R ³ and R ^{4 are} preferably hydrogen or CH ₃ , and particularly preferably hydrogen. From the viewpoint of the balance between the transmittance and the strength of the cured film obtained from the ink, R ⁵ , R ⁶ and R ^{7 are} preferably an ethyl group, a propyl group or a butyl group, and more preferably an ethyl group.

Specific examples of the (meth) acrylate represented by the formula (1) include trimethylolpropane propylene oxide (PO) modified (3 mol) triacrylate, and trimethylolpropane PO. Modified (6 moles) triacrylate, trimethylolpropane PO modified (9 moles) triacrylate, trimethylolpropane ethylene oxide (EO) modified (3 moles) Triacrylate, trimethylolpropane EO modified (6 moles) triacrylate, trimethylolpropane EO modified (9 moles) triacrylate, PO modified (3 moles) triglyceride , PO modified (6 moles) glycerol triacrylate, PO modified (9 moles) glycerol triacrylate, EO modified (3 moles) glycerol triacrylate, EO modified (6 moles) glycerol Acrylate, EO modified (9 moles) glycerol triacrylate. In addition, "EO modification" means modification of ethylene oxide, "PO modification" means modification of propylene oxide, and the number of moles in parentheses means ethylene oxide or propylene oxide added per molecule. quantity.

Among the (meth) acrylates, especially if trimethylolpropane PO modified (3 mole) triacrylate, EO modified (3 mole) glycerin triacrylate is used, the ink of the present invention is not only It is excellent in photocurability, and obtains a cured film having good transmittance, adhesion to a substrate, and strength. Further, when EO-modified (3 mol) glycerin triacrylate is used, the transmittance of the cured film is the highest. good.

The (meth) acrylate (A) represented by the formula (1) may be one selected from the above compounds, or a mixture of two or more kinds of these compounds.

The (meth) acrylate (A) represented by the formula (1) described above can be produced by a known method, and is also commercially available. For example, it is commercially available as trimethylolpropane PO modified (3 mole) triacrylate (M-310: trade name, manufactured by East Asia Synthetic Co., Ltd.), and trimethylolpropane PO modified (6 mole). Acrylate (M-320: trade name, manufactured by East Asia Synthetic Co., Ltd.), trimethylolpropane EO modified (3 mol) triacrylate (M-350: trade name, manufactured by East Asia Synthetic Co., Ltd.), Trimethylolpropane EO modified (6 mole) triacrylate (M-360: trade name, manufactured by East Asia Synthetic Co., Ltd.), EO modified (3 mole) glycerin triacrylate (A-GLY-3E) : Trade name, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., EO modified (9 mol) glycerin triacrylate (A-GLY-9E: trade name, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.).

When the content of the (meth) acrylate (A) represented by the formula (1) in the ink of the present invention is 30% by weight to 70% by weight, not only the photocurability is excellent, but also the transmission of the cured film formed by the ink of the present invention. The ratio, the adhesion to the substrate, and the balance of the strength are good, so it is preferably 40 wt% to 65 wt%, more preferably 45 wt% to 60 wt%, particularly preferably 50 wt% to 60 wt%.

<1.3. Monofunctional (meth) acrylate (B)>

Monofunctional (meth) acrylate (B) is not sprayed on the ink of the present invention The compound and the photocurability, and a compound which is affected by the adhesion, transmittance, and strength of the cured film obtained from the ink and which can reduce the viscosity of the ink of the present invention.

Further, by using the monofunctional (meth) acrylate (B), the adhesion to the substrate, the transmittance, and the strength necessary for the microlens array obtained from the cured film can be maintained.

The monofunctional (meth) acrylate (B) is not particularly limited as long as it satisfies the above characteristics, and is preferably a monofunctional (meth) acrylate having an alkyl group, and more preferably having a carbon number of 1 to 6. a monofunctional (meth) acrylate having an alkyl moiety, particularly preferably a monofunctional (meth) acrylate having an alkyl moiety having 2 to 4 carbon atoms, particularly preferably an alkyl moiety having a carbon number of 4. Monofunctional (meth) acrylate.

Specific examples of the monofunctional (meth) acrylate (B) include cyclohexyl (meth) acrylate, n-hexyl (meth) acrylate, and dicyclopentenyl (meth) acrylate. ), dicyclopentenyloxy ethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isopropionate (meth)acrylate (isobornyl (meth)acrylate), 4-butyl cyclohexyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate (2- Methyl-2-adamantyl(meth)acrylate), 2-ethyl-2-adamantyl(meth)acrylate, (meth)acrylic acid 3,5- 3,5-dimethyl-7-hydroxy adamantyl (meth)acrylate, 3-hydroxy-1-methacryloxy adamantane (3-hydroxy-1-methacryloxy) Adamantane), 3-hydroxy-1-adamantyl (meth)acrylate, ethyl cyclopentyl (meth)acrylate , 3,5-dihydroxy-1-methylpropenyloxy gold (3,5-dihydroxy-1-methacryloxy adamantane), methacryloyloxy norbornane methacrylate, tetrahydrofurfuryl (meth)acrylate, Caprolactone modified (tetramethyl methacrylate), N-acryloyloxy ethyl hexahydrophthalimide, cyclic trimethylol Propane acrylate, γ-butyrolactone (meth) acrylate, mevalonolactone (meth) acrylate, cyclic oxime Amine acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, methyl phenoxyethyl (meth) acrylate Phenoxy ethyl (meth)acrylate), 2-phenoxy ethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate ethylene oxide and / Or propylene oxide addition monomer, 4-t-butyl cyclohexyl (meth)acrylate, cyclohexene Cyclohexyl dimethanol mono(meth)acrylate, 2-hydroxy-3-phenoxy propyl acrylate, (meth) acrylate Ester, ethyl (meth) acrylate, isopropyl (meth) acrylate, isoamyl (meth) acrylate, isobutyl (meth) acrylate , n-butyl (meth)acrylate, tert-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)acrylate, lauryl (meth)acrylate, stearyl(meth)acrylate, (A) 2-hydroxyethyl acrylate (2-hydroxy ethyl(meth)acrylate), 2-hydroxy propyl(meth)acrylate, 4-hydroxybutyl(meth)(meth) Acrylate), 1,4-cyclohexanedimethanol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-Ethyloxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate , ethoxy diethylene glycol (meth)acrylate, methoxy dipropylene glycol (meth)acrylate, dipropylene glycol (methyl) Dipropylene glycol (meth)acrylate, ethyl diglycol (meth)acrylate, glycerol mono(meth)acrylate, Trifluoroethyl (meth)acrylate, glycidyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, (A) Acrylic acid Glycidyl ester, 3-methyl-3-(meth)acryloxymethyl oxetane, 3-ethyl-3-(A) Acryloxymethyloxycyclobutane, 3-methyl-3-(methyl)propenyloxyethyloxycyclobutane, 3-ethyl-3-(methyl)propenyloxy Ethyloxycyclobutane, p-vinylphenyl-3-ethyloxocyclobutane-3-ylmethyl ether, 2-phenyl-3-(methyl)propenyloxymethyloxycyclobutane, 2-trifluoromethyl-3-(methyl)propenyloxymethyloxycyclobutane, 4-trifluoromethyl-2-(methyl)propenyloxymethyloxycyclobutane, (A (3-ethyl-3-oxetanyl)methyl acrylate, ω-carboxypolycaprolactone mono(meth) acrylate, succinic acid mono[2-(methyl) propylene oxy ethoxylate Ester, maleic acid mono [2-(methyl) propylene methoxyethyl] ester and 2-(meth) acryloxy acid phosphate ), and (meth)acrylic acid.

Among these monofunctional (meth)acrylates, cyclohexyl (meth)acrylate, n-hexyl (meth)acrylate, n-butyl (meth)acrylate, and tert-butyl (meth)acrylate are used. (isopropyl) (meth)acrylate, ethyl (meth)acrylate, or methyl (meth)acrylate, sprayability and photocurability, and transmittance of the cured film obtained from the ink, and adhesion to the substrate The balance of sexuality and intensity has become good. From these viewpoints, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, isopropyl (meth)acrylate, ethyl (meth)acrylate, and more preferably N-butyl methacrylate, tert-butyl (meth)acrylate.

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

When the content of the monofunctional (meth) acrylate (B) is from 20% by weight to 60% by weight based on the total amount of the ink of the present invention, the ink can be adjusted to have a viscosity in accordance with the use used, and therefore it is preferred. More preferably, it is 25 wt% to 50 wt%, particularly preferably 30 wt% to 45 wt%, particularly preferably 30 wt% to 40 wt%, in consideration of balance with other characteristics.

<1.4. Photopolymerization initiator (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 can generate a radical by irradiation with ultraviolet light or visible light, and is preferably an α-hydroxyalkylphenone or a fluorenylphosphine oxide. The photopolymerization initiator, in particular, the fluorenyl phosphine oxide-based compound is more preferable from the viewpoint of photocurability and transmittance of the cured film obtained from the ink.

Further, from the viewpoint of the transmittance of the microlens array obtained from the cured film, a fluorenylphosphine oxide-based compound is particularly preferable.

Specific examples of the photopolymerization initiator (C) include benzophenone, Michler's ketone, and 4,4'-bis(diethylamino)benzophenone (4). , 4'-bis(diethylamino)benzophenone), xanthone, 9-thioxanthone, isopropyl xanthone, 2,4-diethyl-9-thioxan 2,4-diethyl thioxanthone, 2-ethyl anthraquinone, acetophenone, 2-hydroxy-2-methyl propiophenone , 2-hydroxy-2-methyl-4'-isopropyl propiophenone, 1-hydroxy cyclohexyl phenyl ketone , isopropyl benzoin ether, isobutyl benzoin ether, 2,2-diethoxy acetophenone, 2,2-dimethoxy 2,2-dimethoxy-2-phenyl acetophenone, camphorquinone, benzantrone, 2-methyl-1-[4-(methylsulfide) Phenyl]-2-morpholinylpropan-1-one (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopro Pan-1-one), 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone-1 (2-benzyl-2-dimethylamino-1-(4-) Morpholinophenyl)-butan one-1), ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 4,4'-2,4'-di(t-butyl peroxycarbonyl)benzophenone, 3,4,4'-tris(t-butylperoxycarbonyl)diphenyl Methyl ketone, 3,3',4,4'-tetrakis(t-butylperoxycarbonyl)benzophenone, 3,3',4,4'-tetra(trihexylperoxycarbonyl)benzol Ketone, 3,3'-bis(methoxycarbonyl)-4,4'-bis(t-butylperoxycarbonyl)benzophenone, 3,4'-bis(methoxycarbonyl)-4, 3'-bis(t-butylperoxycarbonyl)benzophenone, 4,4'-bis(methoxycarbonyl)-3,3'-di(t-butylperoxycarbonyl)benzophenone 2-(4'-methoxystyryl)-4,6-bis(trichloromethyl)-s-trimethylmethyl-(3-(4'-methoxy styryl)-4,6-bis(trichloromethyl)- S-triazine), 2-(3',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(2',4'-dimethyl Oxystyryl)-4,6- Bis(trichloromethyl)-s-triazine, 2-(2'-methoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4'-pentyloxy Styryl)-4,6-bis(trichloromethyl)-s-triazine, 4-[p-N,N-bis(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-dimethylamino styryl)benzoxazole, 2-(p-dimethylamine) 2-(p-dimethylamino styrylbenzothiazole), 2-mercapto benzothiazole, 3,3'-carbonyl bis(7-diethylamine coumarin (3,3'-carbonyl bis(7-diethyl amino)coumarin), 2-(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole ( 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'-four Phenyl-1,2'-biimidazole, 2,2'-bis(2,4-dibromophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4,6-trichlorophenyl)- 4,4',5,5'-tetraphenyl-1,2'-biimidazole, 3-(2-methyl-2-dimethylaminopropionyl)carbazole (3-(2-methyl) -2-dimethylamino propionyl)carbazole), 3,6-bis(2-methyl-2-morpholinylpropionyl)-9-n-dodecylcarbazole, 1-hydroxycyclohexyl phenyl ketone, double (η ⁵ -2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium (bis(η ⁵ -2) ,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyr rol-1-yl)-phenyl)titanium), bis(2,4,6-trimethylbenzhydrazide) Phenylphosphine oxide and 2,4,6-trimethyl benzhydryldiphenylphosphine oxide.

Among the photopolymerization initiators, particularly preferred are 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-4'-isopropylpropiophenone, and 1-hydroxycyclohexyl phenyl ketone. , bis(2,4,6-trimethylbenzylidene)phenylphosphine oxide and 2,4,6-trimethylbenzimidyldiphenylphosphine oxide.

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

When the content of the photopolymerization initiator (C) is from 1% by weight to 20% by weight based on the total amount of the ink of the present invention, the ink of the present invention is particularly excellent in ultraviolet light curability and can maintain high transmittance, so that Preferably, it is preferably from 2 wt% to 15 wt%, more preferably from 3 wt% to 10 wt%.

<1.5. Other ingredients>

In order to improve various characteristics, the inkjet 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.

(1.5.1. Phenolic resin)

In the inkjet ink of the present invention, a phenol resin may be contained in order to increase the strength of the cured film obtained from the ink.

The phenol resin is preferably a phenol resin obtained by a condensation reaction of an aromatic compound having a phenolic hydroxyl group with an aldehyde, a homopolymer of a vinyl phenol (including a hydride), and a vinyl phenol copolymerizable therewith. A vinyl phenol-based copolymer (including a hydride) of the compound.

Specific examples of the aromatic compound having a phenolic hydroxyl group include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol. (o-ethyl phenol), m-ethyl phenol, p-ethyl phenol, o-butyl phenol, m-butyl phenol , p-butyl phenol, o-xylenol, 2,3-xylenol, 2,4-xylenol ), 2,5-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3 , 5,3,5-trimethyl phenol, 3,4,5-trimethyl phenol, p-phenyl phenol, Resorcinol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, bisphenol A, bisphenol F), a diphenol containing a terpene skeleton, gallic acid, gallic acid ester, α-naphthol, and β-naphthol.

Specific examples of the aldehydes include formaldehyde (formaldehyde), para-formaldehyde, furfural, benzaldehyde, nitrobenzaldehyde, and acetaldehyde.

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

Specific examples of the phenol resin include Resitop PSM-6200 (manufactured by QunRong Chemical Co., Ltd.), Shonol BRG-555 (manufactured by Showa Polymer Co., Ltd.), Maruka Lyncur M S-2P, Maruka Lyncur CST70, and Maruka Lyncur PHM. -C (made by Maruzen Petrochemical Co., Ltd.).

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

When the content of the phenol resin is from 0.5% by weight to 20% by weight based on the total amount of the ink of the present invention, the strength of the cured film obtained from the ink is improved, so that it is preferable to consider the balance with other characteristics. 0.5 wt% to 10 wt%, particularly preferably 0.5 wt% to 7 wt%.

(1.5.2. Melamine resin)

In the inkjet ink of the present invention, in order to increase the strength of the cured film obtained from the ink, a melamine resin may be contained.

The melamine resin is not particularly limited as long as it is a resin produced by polycondensation of melamine and formaldehyde, and specific examples thereof include methylol melamine, etherified methylol melamine, and benzoguanamine. And hydroxymethyl benzoguanamine, etherified hydroxymethyl benzoguanamine and condensates of the melamines, of which hydroxymethyl melamine is preferred.

Further, specific examples of the commercial product of the melamine resin include Nikalac MW-30, MW-30HM, MW-390, MW-100LM, MX-750LM (manufactured by Chemicals Co., Ltd.).

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

When the content of the melamine resin is from 0.5% by weight to 20% by weight based on the total amount of the ink of the present invention, the strength of the cured film obtained from the ink is improved, so that it is preferable to consider the balance with other characteristics. 0.5 wt% to 10 wt%, particularly preferably 0.5 wt% to 7 wt%.

(1.5.3. Epoxy resin)

In the inkjet ink of the present invention, an epoxy resin may be contained in order to increase the strength of the cured film obtained from the ink.

The epoxy resin is a compound having at least one structure derived from the epoxide represented by the formula (2-1) or the formula (2-2) in one molecule (hereinafter also simply referred to as "epoxy structure"). , there is no special limit.

Specific examples of the epoxy resin include a novolac type (phenol novolac type and cresol novolak type), a bisphenol A type, a bisphenol F type, a hydrogenated bisphenol A type, a hydrogenated bisphenol F type, and a double Phenol S type, triphenol methane type, tetraphenol ethane type, bixylenol type, biphenol type, alicyclic type and heterocyclic epoxy compound, An epoxy compound having a dicyclopentadiene skeleton or a naphthalene skeleton, preferably a phenolic type, a bisphenol A type, and a bisphenol F type epoxy compound, of which a bisphenol A type and a bisphenol F type epoxy compound are particularly preferable. .

The epoxy resin can be produced by a known method, and is also commercially available. Examples of the commercially available product include Epikote 828, Epikote 834, Epikote 1001, Epikote 1004 (manufactured by Nippon Epoxy Co., Ltd.), Epicron 840, Epicron 850, Epicron 1050, Epicron 2055 (manufactured by DIC), and Epotohto. YD-011, Epotohto YD-013, Epotohto YD-127, Epotohto YD-128 (manufactured by Tohto Kasei Co., Ltd.), DER317, DER331, DER661, DER664 (manufactured by Dow Chemical Japan), Araldite 6071 , Araldite 6084, Araldite GY250, Araldite GY260 (manufactured by Ciba Japan), Sumi-Epoxy ESA-011, Sumi-Epoxy ESA-014, Sumi-Epoxy ELA-115, Sumi-Epoxy ELA-128 (Sumitomo Chemical Industry ( Manufacture of bisphenol A type epoxy compound such as AER330, AER331, AER661, AER664 (manufactured by Asahi Kasei E-Materials); Epikote 152, Epikote 154 (made by Japan Epoxy Resin Co., Ltd.) ), DER431, DER438 (manufactured by Dow Chemical Japan), Epicron N-730, Epicron N-770, Epicron N-865 (manufactured by DIC), Epotohto YDCN-701, Epotohto YDCN-704 (East Capital) Chemical (share) manufacturing), Araldite ECN1235, Araldite ECN1273, Araldite ECN1299 (Ciba Japan) Manufacture, XPY307, EPPN-201, EOCN-1025, EOCN-1020, EOCN-104S, RE-306 (manufactured by Nippon Kayaku Co., Ltd.), Sumi-Epoxy ESCN-195X, Sumi-Epoxy ESCN-220 (Sumitomo Chemical Phenolic epoxy compound such as AERECN-235, AERECN-299 (manufactured by Asahi Kasei E-Materials); Epicron 830 (manufactured by DIC), JER807 (Japanese epoxy resin) (manufacturing), bisphenol F-type epoxy compound such as Epotohto YDF-170 (manufactured by Tohto Kasei Co., Ltd.), YDF-175, YDF-2001, YDF-2004, Araldite XPY306 (manufactured by Ciba Japan Co., Ltd.); Hydrogenated bisphenol A epoxy compounds such as Epotohto ST-2004, Epotohto ST-2007, Epotohto ST-3000 (manufactured by Dongdu Chemical Co., Ltd.); Celloxide 2021P (manufactured by Daicel Chemical Industry Co., Ltd.), Araldite CY175, Araldite CY179 ( An alicyclic epoxy compound such as Ciba Japan (manufactured by Ciba Japan); a trihydroxyphenyl group such as YL-933 (manufactured by Nippon Epoxy Resin Co., Ltd.), EPPN-501, and EPPN-502 (manufactured by Dow Chemical Japan Co., Ltd.) Methane type epoxy compound; YL-6056, YX-4000, YL-6121 (manufactured by Nippon Epoxy Resin Co., Ltd.) and the like, or a bisphenol type or a biphenol type epoxy compound or the like Compound; bisphenol S type epoxy compound such as EBPS-200 (manufactured by Nippon Kayaku Co., Ltd.), EPX-30 (manufactured by ADEKA), EXA-1514 (manufactured by DIC); JER157S (Japanese ring) Oxygen resin (manufactured by oxy-resin), bisphenol A phenolic epoxy compound; YL-931 (made by Nippon Epoxy Resin Co., Ltd.), Araldite 163 (manufactured by Ciba Japan Co., Ltd.), etc. Ethylene epoxy compound; heterocyclic epoxy compound such as Araldite PT810 (manufactured by Ciba Japan), TEPIC (manufactured by Nissan Chemical Industries Co., Ltd.); HP-4032, EXA-4750, EXA-4700 (DIC( Ethylene compound-containing epoxy compound; HP-7200, HP-7200H, HP-7200HH (manufactured by DIC), etc.; epoxy compound having a dicyclopentadiene skeleton; benzodimethyl peroxide Xylylene bisoxetane.

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

If the content of the epoxy resin is from 0.5% by weight to 20% by weight based on the total amount of the ink, the strength of the cured film obtained from the ink of the present invention is improved, so that it is preferably from 0.5% by weight to 10% by weight, more preferably 0.5 wt% to 7 wt%.

(1.5.4. Epoxy hardener)

When the inkjet ink of the present invention contains an epoxy resin, an epoxy hardener may be further added in order to increase the strength of the cured film. The epoxy curing agent is preferably an acid anhydride curing agent, an amine curing agent, or a catalyst type curing agent.

Specific examples of the acid anhydride-based curing agent include maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrotrimellitic anhydride, and o Phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, methyltetrahydrophthalic anhydride, 3,6-endomethylene tetrahydrophthalic anhydride , hexachloromethylenetetrahydrophthalic anhydride, methyl-3,6-endomethylenetetrahydrophthalic anhydride, and styrene-maleic anhydride copolymer.

Specific examples of the amine-based curing agent include diethylene triamine, triethylene tetramine, tetraethylene pentamine, dicyandiamide, and polyfluorene. Polyamide amine (polyamide resin), ketimine compound, isophorone diamine, m-xylene diamine, m-phenylenediamine (m) -phenylene diamine), 1,3-bis(aminomethyl)cyclohexane, N-amino ethyl piperazine, 4,4'-diaminodiphenylmethane, 4 4'-Diamino-3,3'-diethyldiphenylmethane and diamino diphenyl sulfone.

Specific examples of the catalyst type curing agent include a tertiary amine compound and an imidazole compound.

The epoxy hardener used in the ink of the present invention may be one compound or a mixture of two or more compounds.

If the content of the epoxy curing agent is from 0.5% by weight to 20% by weight based on 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, so that it is preferably from 0.5% by weight to 10% by weight. %, especially preferably 0.5 wt% to 7 wt%.

(1.5.5. Surfactant)

For example, the inkjet ink of the present invention may contain a surfactant in order to improve the wettability to the base substrate or the film surface uniformity of the cured film obtained from the ink. The surfactant is a ruthenium-based surfactant, an acrylic surfactant, a fluorine-based surfactant, or the like.

Specific examples of the surfactant include, for example, Byk-300, Byk-306, Byk-335, Byk-310, Byk-341, Byk-344, and Byk-370 (manufactured by BYK-Chemie Japan). Surfactant; acrylic surfactant such as Byk-354, Byk-358, and Byk-361 (manufactured by BYK-Chemie Japan Co., Ltd.); DFX-18, Ftergent 250, or Ftergent 251 (manufactured by Neos) And a fluorine-based surfactant such as Megafac F-475, F-477, F-553, and F-554 (manufactured by DIC).

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

When the content of the surfactant is from 0.001% by weight to 1% by weight based on the total amount of the ink of the present invention, the uniformity of the film surface of the cured film obtained from the ink is improved, and therefore, in consideration of balance with other characteristics, More preferably, it is 0.001 wt% to 0.1 wt%, and particularly preferably 0.001 wt% to 0.05 wt%.

(1.5.6. Other compounds having a radical polymerizable double bond)

In addition to the (meth) acrylate (A) and the monofunctional (meth) acrylate (B) represented by the formula (1), the inkjet ink of the present invention can also impair the ejection of the ink of the present invention. The compound having a radical polymerizable double bond is added to the range of the adhesion, the transmittance, and the strength of the cured film obtained from the ink to the substrate.

Specific examples of the other compound having a radical polymerizable double bond include bis(hydroxymethyl)tricyclodecane di(meth)acrylate and tricyclodecane dimethylol di(meth)acrylate. Bisphenol F EO modified di(meth) acrylate, bisphenol A EO modified di(meth) acrylate, polypropylene glycol di(meth) acrylate, isomeric cyanuric acid EO modified di(methyl Acrylate and tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol II (Meth) acrylate, polyethylene glycol di(meth) acrylate, 1,4-butanediol di(meth) acrylate, 1,6-hexanediol di(meth) acrylate, new Pentanediol di(meth)acrylate, or trimethylolpropane trioxyethyl (meth) acrylate, (meth) acrylate dimer, crotonic acid, alpha chloro acrylate , cinnamic acid, maleic acid, fumaric acid, N-vinylformamide, and polymethyl methacrylate macromonomer, N-cyclohexylmethyleneimine, N-benzene Isobutene diimide, (a Acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dimethylaminopropyl (methyl) And acrylamide, N-isopropyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide.

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

When the content of the other compound having a radical polymerizable double bond is from 0.1% by weight to 20% by weight based on the total amount of the ink of the present invention, the photocurability and the adhesion of the cured film to the substrate, the transmittance, and the strength are balanced. It is preferably, preferably, more preferably from 0.1 wt% to 10 wt%, particularly preferably from 0.1 wt% to 5 wt%.

(1.5.7. Solvent)

The inkjet ink of the present invention can also be added with a solvent in a range that does not impair the inkjettability and photocurability of the ink of the present invention, and the adhesion, transmittance, and strength of the cured film obtained from the ink to the substrate.

The solvent which can be used in the present invention is preferably a solvent having a boiling point higher than a temperature at which the ink jet head is heated, and more specifically a solvent having a boiling point of from 100 ° C to 300 ° C from the viewpoint of ejection characteristics. In the case where the ink jet head is heated to a high temperature (for example, 70 ° C to 120 ° C), a solvent having a boiling point of 200 ° C to 300 ° C is preferable.

Among them, in the case of heating the ink jet head, it is preferred that the ink of the present invention contains substantially no solvent.

Specific examples of the solvent having a boiling point of 100 ° C to 300 ° C include butyl acetate, butyl propionate, ethyl lactate, methyl oxyacetate, ethyl oxyacetate, butyl oxyacetate, methyl methoxyacetate, Ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate, methyl 3-oxopropionate, ethyl 3-oxopropionate, 3-methoxypropane Methyl ester, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 2-oxopropionate, ethyl 2-oxopropionate, Propyl 2-oxopropionate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, methyl 2-ethoxypropionate, 2- Ethyl ethoxypropionate, methyl 2-oxo-2-methylpropanoate, ethyl 2-oxo-2-methylpropanoate, methyl 2-methoxy-2-methylpropionate, 2 - Ethoxy-2-methylpropionic acid ethyl ester, methyl pyruvate, ethyl pyruvate, propyl pyruvate, methyl ethyl acetate, ethyl acetate, ethyl 2-oxobutanoate, 2-sided oxybutyric acid ethyl ester, dioxane, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, ethylene 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 Ethyl ether, toluene, xylene, anisole, γ-butyrolactone, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and two Methyl imidazolidinone.

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

If the content of the solvent is from 0.1% by weight to 20% by weight based on the total amount of the ink of the present invention, the nozzle is not easily dried at the time of spraying, which is preferable. More preferably, it is 0.1 wt% to 10 wt%, and particularly preferably 0.1 wt% to 5 wt%, in consideration of balance with other characteristics.

(1.5.8. Polymerization inhibitor)

In order to improve storage stability, the inkjet ink of the present invention may further contain a polymerization inhibitor. Specific examples of the polymerization inhibitor include 4-methoxyphenol, hydroquinone, and thiodiphenylamine. Among these polymerization inhibitors, thiodiphenylamine is preferred because the viscosity (increase) of the ink during long-term storage is small.

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

When the content of the polymerization inhibitor is from 0.01 wt% to 1 wt% based on the total amount of the ink of the present invention, the change in viscosity during long-term storage is small, so that it is preferably 0.01 in consideration of balance with other characteristics. From wt% to 0.5 wt%, particularly preferably from 0.01 wt% to 0.1 wt%.

<1.6. Method for Producing Photocurable Inkjet Ink of the Present Invention>

The inkjet ink of the present invention can be prepared by mixing the components which are raw materials by a known method.

The ink of the present invention is preferably prepared by mixing the above components (A) to (C) and optionally other components, and filtering and degassing the resulting solution. The ink of the present invention prepared in this manner is excellent in ejectability. For the above filtration, for example, a membrane filter made of a fluororesin is used.

<1.7. Storage of Inkjet Ink of the Present Invention>

When the ink for inkjet of the present invention is stored at -20 ° C to 25 ° C, the viscosity change (increased) during storage is small, and the storage stability is good.

[2. Coating of ink for inkjet using an inkjet method]

The inkjet ink of the present invention can be applied by a known inkjet coating method. The inkjet coating method includes, for example, a method in which mechanical energy is applied to the ink to eject (coat) the ink from the inkjet head (so-called piezoelectric method), and a coating method in which thermal energy is applied to the ink to apply the ink. (so-called bubble jet (registered trademark) method).

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

Examples of the ink jet head include an ink jet head having a liquid contact surface of a heat generating portion containing a metal and/or a metal oxide. Specific examples of the metal and/or metal oxide include metals such as Ta, Zr, Ti, Ni, and Al, and oxides of these metals.

The coating apparatus which is suitable for the application of the ink of the present invention is, for example, an apparatus that supplies energy corresponding to a coating signal to ink in a chamber of an ink jet head having an ink containing portion in which ink is contained. Coating (drawing) corresponding to the above coating signal is performed while generating ink droplets by the above energy.

The inkjet coating device is not limited to a device in which the inkjet head is separated from the ink containing portion, and an apparatus in which the inkjet head and the ink containing portion are inseparable from each other can be used. Further, the ink accommodating portion may be integrally mounted on the cradle separately or inseparably from the ink jet head, or may be provided at a fixed portion of the device, and may supply ink to the ink jet head via an ink supply member such as a tube. Shape.

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

[3. Formation of hardened film]

The cured film of the present invention is obtained by applying the above-described inkjet ink of the present invention to the surface of a substrate by an inkjet method, and then irradiating the ink with light such as ultraviolet rays or visible rays to cure the coating film.

In the case of irradiating ultraviolet rays, visible rays, or the like, the amount of exposure to be irradiated is determined by the cumulative light meter UIT-201 on which the light receiver UVD-365PD is mounted, which is manufactured by Ushio Electric Co., Ltd., based on the composition of the ink. It is preferably from about 100 mJ/cm ² to about 5,000 mJ/cm ² , more preferably from about 200 mJ/cm ² to about 4,000 mJ/cm ² , and more preferably from about 300 mJ/cm ² to about 3,000 mJ/cm ² . Further, the wavelength of the ultraviolet ray or the visible ray to be irradiated is preferably from 200 nm to 500 nm, more preferably from 300 nm to 450 nm.

In addition, the UV exposure amount described below is a value measured by an integrated photometer UIT-201 equipped with a light receiver UVD-365PD manufactured by Ushio Electric Co., Ltd.

In addition, the exposure machine is not particularly limited as long as it is a device that is irradiated with ultraviolet light or visible light in a range of 250 nm to 500 nm, such as a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, or a halogen lamp.

Further, if necessary, the cured film which is cured by irradiation with light may be further heated and calcined, and heated and calcined at 80 to 250 ° C for 10 minutes to 60 minutes to cure the cured film more firmly.

The "substrate" to which the ink of the present invention is applied, which is 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 thereof is not limited to a flat plate shape, and may be a curved shape.

Further, the material of the substrate is not particularly limited, and examples thereof include polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and polycondensation. Polyolefin resin such as ethylene and polypropylene, plastic film such as polyvinyl chloride, fluororesin, acrylic resin, polyamide, polycarbonate, and polyimide, cellophane, acetate, metal foil, and poly a laminate of bismuthmine and metal foil, a glasse paper with a filling effect, a parchment paper, and a polyethylene, a clay binder, a polyvinyl alcohol, a starch or a carboxymethyl cellulose. Paper and glass subjected to filling treatment such as (carboxy methyl cellulose, CMC).

Among the substances constituting the substrate, additives such as an antioxidant, an anti-deterioration agent, a filler, an ultraviolet absorber, an antistatic agent, and/or an anti-electromagnetic wave agent may be further added in a range that does not adversely affect the effects of the present invention. In addition, a part of the surface of the substrate may be subjected to water repellent treatment, corona treatment, plasma treatment, or blast treatment, etc., or may be subjected to an easy-adhesion layer or a protective film for a color filter or a hard coat. membrane.

The thickness of the substrate is not particularly limited, but is usually about 10 μm to 2 mm, and is appropriately adjusted depending on the purpose to be used, and is preferably 15 μm to 1.5 mm, and more preferably 20 μm to 1 mm.

The use of the substrate is not particularly limited, and the cured film obtained by the inkjet ink of the present invention is excellent in adhesion to the substrate and exhibits high transmittance and high strength. Therefore, it is particularly preferably used for manufacturing a backlight device. Microlens array.

The spot diameter of the cured film of the present invention which functions as a microlens array or the like used in such a backlight device is not particularly limited, but is usually preferably 10 μm to 100 μm, and particularly preferably 20 μm to 60 μm. It is preferably 30 μm to 50 μm. Further, the height of the dots is not particularly limited, but is usually preferably 0.5 μm to 10 μm, more preferably 1 μm to 8 μm, and particularly preferably 2 μm to 6 μm.

A liquid crystal display for a liquid crystal display element can be produced by mounting a backlight manufactured by using the cured film of the present invention as described above.

[Example]

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

<Preparation of Inkjet Ink and Preparation of Cured Film Pattern Forming Substrate>

First, the inkjet inks of Examples 1 to 6 and Comparative Examples 1 to 4 and the cured film pattern forming substrate obtained by the inkjet ink will be described.

[Example 1]

EO-modified (3 mol) glycerin triacrylate A-GLY-3E (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a (meth) acrylate (A) represented by the formula (1), as a monofunctional (Meth) acrylate (B) n-butyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 2,4,6-trimethylbenzhydryl 2 as a photopolymerization initiator (C) Phenylphosphine oxide DAROCUR TPO (trade name, manufactured by Ciba Japan Co., Ltd.), and thiodiphenylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) as a polymerization inhibitor are mixed and dissolved in the following composition ratio, and then 1 μm of PTFE is used. The membrane filter was filtered to prepare an inkjet ink 1.

(A) A-GLY-3E 350.00 g

(B) n-butyl methacrylate 200.00 g

(C) DAROCUR TPO 55.00 g

(other) thiodiphenylamine 0.28 g

The viscosity of the inkjet ink 1 at 25 ° C was measured using an E-type viscometer (TV-22 manufactured by Toki Sangyo Co., Ltd., the same applies hereinafter) and found to be 12 mPa·s.

Two glass substrates of 4 cm square (thickness: 0.7 mm) were prepared, and inkjet ink 1 was injected into an inkjet cartridge, which was mounted on an inkjet device (DMP-2831 manufactured by FUJIFILM Dimatix Inc.). The nozzle for 10 p1 draws a design value of 40 μm on a glass substrate with a discharge voltage (piezo voltage) of 16 V, a nozzle temperature of 30 ° C, a drive frequency of 5 kHz, and a number of times of application. Pattern, and a 3 cm square pattern is drawn on the center of the other glass substrate.

For two substrates on which a dot pattern and a square pattern were drawn using the inkjet ink 1, a UV irradiation device (J-CURE 1500 manufactured by Jatec) was used, and ultraviolet rays were irradiated at a UV exposure amount of 2000 mJ/cm ² . A substrate 1a having dots having a spot diameter of 40 μm and a height of 5.0 μm and a substrate 1b formed with a square pattern of 3 cm and a thickness of 5.0 μm were obtained.

[Example 2]

In addition to using trimethylolpropane EO-modified (3 mol) triacrylate M-350 (manufactured by Toagos Corporation) as the (meth) acrylate (A) represented by the formula (1), and set An inkjet ink 2 was prepared in the same manner as in Example 1 except for the following composition ratio.

(A) M-350 350.00 g

(B) n-butyl methacrylate 200.00 g

(C) DAROCUR TPO 55.00 g

(other) thiodiphenylamine 0.28 g

The viscosity of the inkjet ink 2 at 25 ° C was measured using an E-type viscometer and found to be 10 mPa ‧ s.

Using the inkjet ink 2, a substrate 2a having a dot pattern having a spot diameter of 40 μm and a height of 4.9 μm and a substrate 2b formed with a square pattern of 3 cm and a thickness of 4.8 μm were obtained by the same method as in Example 1.

[Example 3]

An inkjet ink 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. 3.

(A) A-GLY-3E 350.00 g

(B) Ethyl methacrylate 200.00 g

(C) DAROCUR TPO 55.00 g

(other) thiodiphenylamine 0.28 g

The viscosity of the inkjet ink 3 at 25 ° C was measured using an E-type viscometer and found to be 9 mPa ‧ s.

Using the inkjet ink 3, a substrate 3a having a dot pattern having a spot diameter of 39 μm and a height of 4.8 μm and a substrate 3b formed with a square pattern of 3 cm and a thickness of 4.8 μm were obtained by the same method as in Example 1.

[Example 4]

An inkjet ink 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). 4.

(A) A-GLY-3E 350.00 g

(B) n-hexyl methacrylate 200.00 g

(C) DAROCUR TPO 55.00 g

(other) thiodiphenylamine 0.28 g

The viscosity of the inkjet ink 4 at 25 ° C was measured using an E-type viscometer and found to be 14 mPa ‧ s.

Using the inkjet ink 4, a substrate 4a having a dot pattern having a spot diameter of 41 μm and a height of 5.1 μm and a substrate 4b formed with a square pattern of 3 cm and a thickness of 5.1 μm were obtained by the same method as in Example 1.

[Example 5]

The inkjet ink 5 was prepared in the same manner as in Example 1 except that the amount of the (meth) acrylate (A) A-GLY-3E represented by the formula (1) was increased and the composition ratio was as follows.

(A) A-GLY-3E 600.00 g

(B) n-butyl methacrylate 200.00 g

(C) DAROCUR TPO 80.00 g

(other) thiodiphenylamine 0.40 g

The viscosity of the inkjet ink 5 at 25 ° C was measured using an E-type viscometer and found to be 87 mPa ‧ s.

A substrate 5a having a dot pattern having a spot diameter of 40 μm and a height of 5.3 μm and a sheet having a thickness of 3 cm were formed by the same method as in Example 1 except that the inkjet ink 5 was used. A 5.3 μm square patterned substrate 5b.

[Example 6]

In addition to reducing the amount of (meth) acrylate (A) A-GLY-3E represented by formula (1), trimethylolpropane triacrylate M-309 (others synthesized) is added instead of other components. Inkjet ink 6 was prepared in the same manner as in Example 1 except that the following composition ratio was used.

(A) A-GLY-3E 200.00 g

(Other) M-309 150.00 g

(B) n-butyl methacrylate 200.00 g

(C) DAROCUR TPO 55.00 g

(other) thiodiphenylamine 0.28 g

The viscosity of the inkjet ink 6 at 25 ° C was measured using an E-type viscometer and found to be 10 mPa ‧ s.

Using the inkjet ink 6, a substrate 6a having a dot pattern having a spot diameter of 40 μm and a height of 4.9 μm and a substrate 6b formed with a square pattern of 3 cm and a thickness of 5.0 μm were obtained by the same method as in Example 1.

[Comparative Example 1]

In addition to further reducing the amount of (meth) acrylate (A) A-GLY-3E represented by the formula (1), trimethylolpropane triacrylate M-309 of other components was added instead of this, and An inkjet ink 7 was prepared in the same manner as in Example 1 except for the composition ratio.

(A) A-GLY-3E 100.00 g

(Other) M-309 250.00 g

(B) n-butyl methacrylate 200.00 g

(C) DAROCUR TPO 55.00 g

(other) thiodiphenylamine 0.28 g

The viscosity of the inkjet ink 7 at 25 ° C was measured using an E-type viscometer and found to be 10 mPa ‧ s.

Using the inkjet ink 7, a substrate 7a having a dot pattern having a spot diameter of 40 μm and a height of 4.9 μm and a substrate 7b formed with a square pattern of 3 cm and a thickness of 5.0 μm were obtained by the same method as in Example 1.

[Comparative Example 2]

The same procedure as in Example 1 was carried out except that trimethylolpropane triacrylate M-309 having another component was added instead of the (meth) acrylate (A) represented by the formula (1), and the following composition ratio was used. The inkjet ink 8 was prepared in a manner.

(Other) M-309 350.00 g

(B) n-butyl methacrylate 200.00 g

(C) DAROCUR TPO 55.00 g

(other) thiodiphenylamine 0.28 g

The viscosity of the inkjet ink 8 at 25 ° C was measured using an E-type viscometer and found to be 9 mPa ‧ s.

Using the inkjet ink 8, a substrate 8a having a dot pattern having a spot diameter of 39 μm and a height of 4.8 μm and a substrate 8b formed with a square pattern of 3 cm and a thickness of 4.9 μm were obtained by the same method as in Example 1.

[Comparative Example 3]

In addition to the (meth) acrylate (A) represented by the formula (1), propylene oxide-modified neopentyl diacrylate (manufactured by Sartomer Japan Co., Ltd.) containing other components was added, and was set as follows. An inkjet ink 9 was prepared in the same manner as in Example 1 except for the composition ratio.

(Other) SR-9003 600.00 g

(B) n-butyl methacrylate 200.00 g

(C) DAROCUR TPO 60.00 g

(other) thiodiphenylamine 0.30 g

The viscosity of the inkjet ink 9 at 25 ° C was measured using an E-type viscometer and found to be 6 mPa ‧ s.

Using the inkjet ink 9, an attempt was made to produce a pattern substrate by the same method as in Example 1. However, a dot pattern and a cured film were not obtained due to poor curability.

[Comparative Example 4]

In addition to the addition of the (meth) acrylate (A) A-GLY-3E represented by the formula (1), the monofunctional (meth) acrylate (B), and other components of propylene oxide modified neopentyl acrylate In the same manner as in Example 1, SR-9003 was prepared in the same manner as in Example 1.

(A) A-GLY-3E 200.00 g

(Other) SR-9003 200.00 g

(B) n-butyl methacrylate 100.00 g

(C) DAROCUR TPO 50.00 g

(other) thiodiphenylamine 0.25 g

The viscosity of the inkjet ink 10 at 25 ° C was measured using an E-type viscometer and found to be 13 mPa ‧ s.

Using the inkjet ink 10, a substrate 10a having a dot pattern having a spot diameter of 40 μm and a height of 5.1 μm and a substrate 10b formed with a square pattern of 3 cm and a thickness of 5.2 μm were obtained by the same method as in Example 1.

<Evaluation of inkjet ink and patterned cured film>

Next, the inkjet ink obtained by the above-described inkjet ink, the photocurability, the adhesion of the cured film to the substrate, and the transmittance and strength of the cured film were evaluated. Each test method is as follows, and the evaluation results are shown in Tables 1 and 2.

(Injection test of ink)

The dot pattern on the substrates (1a to 10a, 1b to 10b) obtained in each of the examples and the comparative examples, and the disorder of the square pattern of 3 cm square, and the whiteness of printing were observed, and the ejection property of the ink was evaluated. The evaluation criteria are as follows.

○: There is no pattern confusion, and printing is white.

△: The pattern is confusing, and the printing is white.

×: The ink cannot be ejected (that is, the pattern cannot be formed).

(photohardenability test)

The surface of the square pattern substrate (1b to 10b) of 3 cm square obtained in each of the examples and the comparative examples was touched with a finger, and the surface state of the cured film was observed with a microscope. The evaluation criteria are as follows.

○: The finger touch marks did not remain on the surface of the cured film at all.

△: The finger touch trace slightly remained on the surface of the cured film.

×: The finger touch trace completely remains on the surface of the cured film.

(Measurement of transmittance of cured film)

Using a transmittance measuring apparatus V-670 (manufactured by JEOL Ltd.), a square pattern substrate (1b to 10b) of 3 cm square obtained in each of the examples and the comparative examples was used, and the transmittance at a light wavelength of 400 nm was measured. Using a 4 cm square glass substrate (thickness: 0.7 mm) without a cured film For reference.

(Test of adhesion of the cured film to the substrate)

Adhesive tapes ("Polyester tape No. 56: adhesive force, 5.5 N/cm" manufactured by Sumitomo 3M Co., Ltd.) were attached to the dot pattern substrates (1a to 10a) obtained in the respective examples and comparative examples, and then The state of the dot pattern remaining on the substrate at the time of peeling was observed, whereby the adhesion of the cured film to the substrate was evaluated. In addition, the evaluation criteria are as follows.

○: The dot pattern is completely unchanged.

△: A part of the spots peeled off.

×: All points are peeled off.

(strength measurement)

The pencil hardness was measured in accordance with JIS 5400 using the square pattern substrate (1b to 10b) of 3 cm square obtained in each of the examples and the comparative examples, thereby checking the strength.

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

As a result of the results shown in Table 1, it was found that the patterns 1a to 10a and 1b to 10b obtained by using the inkjet ink of the present invention did not show any disorder of the pattern and whitening of the printing, and the ejection characteristics were good.

Next, the photocurability of the ink was evaluated on the substrates 1b to 10b. As a result, in all the substrates other than the substrate 9b, the finger touch marks did not remain on the surface of the cured film, which was good.

On the other hand, on the substrate 9b, the finger touch marks completely remained on the surface of the cured film, and the hardenability was poor, so that the subsequent test was interrupted.

In addition, the transmittance of the light of 400 nm was measured using the substrates 1b to 8b and 10b, and as a result, the transmittance of the substrate 1b>substrate 3b>substrate 4b>substrate 10b>substrate 2b>substrate 6b was increased. On the other hand, the transmittance of the substrate 7b and the substrate 8b is as low as 96% or less.

Furthermore, the adhesion of the cured film was evaluated using the substrates 1a to 8a and 10a, and as a result, the dot patterns of the substrates 1a to 6a and 10a did not change at all, and the adhesion was good. On the other hand, some of the dots on the substrates 7a to 8a are peeled off, and the adhesion is lowered.

Finally, the strength was measured using the substrates 1b to 8b and 10b, and as a result, the cured film of the substrates 1b to 8b showed a pencil hardness of 3H. On the other hand, the cured film of the substrate 10b exhibits a pencil hardness of H and has low strength.

[Industrial availability]

As described above, according to the present invention, it is possible to obtain an inkjet ink which is excellent in ejectability, photocurability, and adhesion of a cured film to a substrate, and can form a cured film having high transmittance and high strength. It can be suitably used for manufacturing an optical device such as a liquid crystal display or a display panel.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

Claims (13)

A photocurable inkjet ink comprising (meth) acrylate (A) represented by formula (1), a monofunctional (meth) acrylate (B), and a photopolymerization initiator (C), Further, the transmittance of the cured film (film thickness: 5 μm) obtained from the ink at a light wavelength of 400 nm is 96% or more. (wherein R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms; and R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a carbon number of 1 ~6 alkylene, k is 0 or 1, l, m and n are each independently an integer from 1 to 10). The ink for inkjet according to claim 1, wherein the inkjet ink contains 30% by weight to 70% by weight of the (meth) acrylate represented by the formula (1) with respect to the total weight of the ink. (A), 20% by weight to 60% by weight of the monofunctional (meth) acrylate (B), and 1% by weight to 20% by weight of the photopolymerization initiator (C). The inkjet ink according to the first or second aspect of the invention, wherein, in the formula (1), R ⁵ , R ⁶ and R ⁷ are each independently an alkylene group having 2 or 3 carbon atoms. The inkjet ink according to any one of the items 1 to 2, wherein, in the formula (1), R ¹ is hydrogen and k is 0. The inkjet ink according to any one of the items 1 to 2, wherein, in the formula (1), l, m and n are 1. The inkjet ink according to any one of claims 1 to 2, wherein the monofunctional (meth) acrylate (B) is a monofunctional group having an alkyl group having 1 to 6 carbon atoms. (Meth) acrylate. The inkjet ink according to any one of the preceding claims, wherein the monofunctional (meth)acrylate (B) is selected from the group consisting of cyclohexyl (meth)acrylate, (a) N-hexyl acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, isopropyl (meth) acrylate, ethyl (meth) acrylate, or methyl (meth) acrylate At least one of the group consisting of. The inkjet ink according to any one of the preceding claims, wherein the photopolymerization initiator (C) is an α-hydroxyalkylphenone or a mercaptophosphine oxide photopolymerization. Starting agent. The inkjet ink according to any one of the items 1 to 2, further comprising a polymerization inhibitor. An inkjet ink according to claim 9, which contains an ethylene oxide-modified glycerin triacrylate (ethylene oxide) as the (meth) acrylate (A) represented by the formula (1). Modified: 3 moles), as a single official N-butyl (meth)acrylate capable of (meth) acrylate (B), 2,4,6-trimethylbenzimidyldiphenylphosphine oxide as a photopolymerization initiator (C), and Thioaniline as a polymerization inhibitor. A cured film obtained by hardening an ink for inkjet according to claim 9 of the patent application. A microlens array obtained by a cured film as described in claim 11 of the patent application. An optical machine comprising the microlens array of claim 12 of the patent application.