JP2022136510A - Inkjet ink composition - Google Patents

Abstract

To provide an inkjet ink composition which secures adhesiveness to various base materials or a coated film and can be cured with high curability.SOLUTION: There is provided an inkjet ink composition which comprises s silane compound and/or a polymerizable compound having a hydroxyl group, a polymerizable compound having a heterocyclic skeleton and a photopolymerization initiator, wherein when the amount (mass%) of a monofunctional polymerizable compound contained in ink composition is defined as A and the amount (mass%) of a polyfunctional polymerizable compound contained in the ink composition is defined as B, 0.03≤B/A≤0.30 and 50 mass%≤A+B≤95 mass%.SELECTED DRAWING: None

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet ink composition, and more particularly to an inkjet ink composition that ensures adhesion to various substrates and coating films and that is highly curable.

Inkjet ink is used to decorate substrates such as paper and building boards. In recent years, active energy ray-curable inks, which have a short curing time and excellent productivity, have attracted attention. ing.

International Publication No. 2012/133667 (Patent Document 1) discloses a method for producing a multilayer coating film in which an undercoat film layer, an active energy ray-curable ink layer, and a topcoat film layer are formed on a base material. By setting the surface free energy of the film layer, the surface tension of the active energy ray-curable ink, and the surface free energy of the top coat within specific ranges, the surface has a highly designed pattern, adhesion, and water resistance. and that a veneer for building interiors and exteriors having excellent weather resistance can be obtained. Patent Literature 1 describes that a preferable form of active energy ray-curable ink contains 50 to 90% by mass of a monomer having an ethylenically unsaturated group.

Japanese Patent Application Laid-Open No. 2016-65200 (Patent Document 2) describes an invention relating to an active energy ray-curable inkjet ink composition capable of forming a printed matter having excellent adhesion to a substrate, wherein the radically polymerizable monomer is It is described that the use of a specific (meth)acrylic acid ester compound having a hydroxyl group can improve the adhesion of the printed layer to the substrate.

Japanese Patent Application Laid-Open No. 2020-55901 (Patent Document 3) discloses an active energy ray-curable inkjet that has excellent adhesion to a substrate such as a glass substrate, has sufficient hardness, and can form a scratch-resistant printed layer. An invention for the purpose of providing an ink composition is described, specifically, an alicyclic monofunctional (meth)acrylate having a specific glass transition temperature and a hydroxyl group-containing monofunctional Active energy ray curing comprising a (meth)acrylate and a trifunctional or higher polyfunctional (meth)acrylate having a specific (meth)acrylic equivalent, wherein the amount of the polyfunctional (meth)acrylate is within a specific range A type inkjet ink composition invention is described.

Japanese Patent Application Laid-Open No. 2019-217680 (Patent Document 4) describes an invention relating to a printed material obtained by laminating an ink layer made of an active energy ray-curable ink and a surface protective layer on a substrate, where the ink layer is It is described that by setting the monomer diffusion rate and the monomer diffusion rate of the surface protective layer within a certain range, it is possible to provide a printed material with less diffusion of unreacted monomers.

WO2012/133667 Japanese Patent Application Laid-Open No. 2016-65200 Japanese Patent Application Laid-Open No. 2020-55901 Japanese Patent Application Laid-Open No. 2019-217680

As for the polymerizable compound used in the active energy ray-curable ink composition, by blending a monofunctional polymerizable compound, it becomes easier to obtain a printed film with excellent adhesion to the substrate and flexibility of the cured film. The functional polymerizable compound alone cannot form a crosslinked structure, resulting in weak film strength and poor curability. On the other hand, polyfunctional polymerizable compounds tend to form a printed film with high film strength due to the formation of a crosslinked structure. If the compound is used alone, there is a problem with adhesion due to the effects of cure shrinkage. Therefore, the ratio of the monofunctional polymerizable compound to the polyfunctional polymerizable compound is important for obtaining good film properties.

However, simply adjusting the ratio of the monofunctional polymerizable compound and the polyfunctional polymerizable compound is inadequate when considering adhesion to various substrates, adhesion to undercoat and topcoat films, and ink curability. It is enough.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an inkjet ink composition that ensures adhesion to various substrates and coating films and that is highly curable.

As a result of intensive studies to achieve the above object, the present inventors have determined that the amounts of the monofunctional polymerizable compound and the polyfunctional polymerizable compound contained in the ink composition are specified in a specific ratio, and the silane compound and/or Alternatively, the inventors have found that by using a polymerizable compound having a hydroxyl group, adhesion to various substrates and coating films can be ensured. Furthermore, the inventors have also found that the curability of the ink can be improved by using a polymerizable compound having a heterocyclic skeleton as the polymerizable compound contained in the ink composition.

Therefore, the first aspect of the present invention comprises a silane compound and / or a polymerizable compound having a hydroxyl group, a polymerizable compound having a heterocyclic skeleton, and a photopolymerization initiator,
When A is the amount (% by mass) of the monofunctional polymerizable compound contained in the ink composition and B is the amount (% by mass) of the polyfunctional polymerizable compound contained in the ink composition, 0.03≦ An inkjet ink composition characterized in that B/A≦0.30 and 50% by mass≦A+B≦95% by mass.

In a preferred example of the inkjet ink composition of the present invention, the average functional group number of the polymerizable compound contained in the ink composition is 1.2 or less.

In another preferred embodiment of the inkjet ink composition of the present invention, the polymerizable compound having a heterocyclic skeleton is a nitrogen-containing polymerizable compound.

In another preferred embodiment of the inkjet ink composition of the present invention, the polymerizable compounds contained in the ink composition include 1 to 20% by mass of a bifunctional polymerizable compound having a molecular weight of 300 to 1,500 and a monofunctional polymerizable compound. Contains 55 to 80% by mass.

In another preferred embodiment of the inkjet ink composition of the present invention, P.I. I. I. The weighted average of the values is less than 2.00.

ADVANTAGE OF THE INVENTION According to this invention, the adhesiveness to various base materials and a coating film is ensured, and the inkjet ink composition which can be hardened|cured with high curability can be provided.

The present invention will be described in detail below.

One aspect of the invention is an inkjet ink composition comprising a polymerizable compound and a photoinitiator. This inkjet ink composition is also referred to herein as the "ink composition of the present invention." An inkjet ink means an ink used in an inkjet printing method.

Since the inkjet ink composition of the present invention contains a polymerizable compound and is an ink composition that can be cured by irradiation with active energy rays such as ultraviolet rays, visible rays, and electron beams, it is an active energy ray-curable ink composition. It is suitable as

The polymerizable compound undergoes a polymerization reaction via a functional group that exhibits radical polymerizability (for example, a photopolymerizable unsaturated group such as a carbon-carbon double bond that constitutes an acryloyl group, a methacryloyl group, a vinyl group, or an allyl group). It is a compound that causes A carbon-carbon double bond that exhibits radical polymerizability is also referred to as an "ethylenically unsaturated double bond". A polymerizable compound may be used individually by 1 type, and may be used in combination of 2 or more types.

Polymerizable compounds are classified as monofunctional polymerizable compounds or multifunctional polymerizable compounds. Here, the monofunctional polymerizable compound includes a monofunctional polymerizable monomer having one radically polymerizable functional group (for example, a monofunctional polymerizable monomer having one polymerizable unsaturated group) or a radically polymerizable compound. A monofunctional polymerizable oligomer having one functional group (for example, a monofunctional polymerizable oligomer having one polymerizable unsaturated group) and the like can be mentioned. As the polyfunctional polymerizable compound, a polyfunctional polymerizable monomer having two or more radically polymerizable functional groups (for example, a polyfunctional polymerizable monomer having two or more polymerizable unsaturated groups) or a radically polymerizable Polyfunctional polymerizable oligomers having two or more functional groups (for example, polyfunctional polymerizable oligomers having two or more polymerizable unsaturated groups), and the like.

In the ink composition of the present invention, A is the amount (% by mass) of the monofunctional polymerizable compound contained in the ink composition, and B is the amount (% by mass) of the polyfunctional polymerizable compound contained in the ink composition. , 0.03≦B/A≦0.30 and 50% by mass≦A+B≦95% by mass. The present inventors found that in an ink composition in which the total amount of polymerizable compounds is 50 to 95% by mass, by setting the ratio of the polyfunctional polymerizable compound to the monofunctional polymerizable compound to 0.30 or less, curing shrinkage of the film can be suppressed, and the adhesion of the film itself can be improved. This makes it possible to ensure adhesion to various substrates and coating films. Furthermore, curability and film strength can be ensured by adjusting the amounts of the monofunctional polymerizable compound and the polyfunctional polymerizable compound contained in the ink composition to the above-specified ratio. Here, B/A is preferably 0.10 to 0.30. Also, A+B is preferably 60 to 95% by mass.

The polymerizable compound contained in the ink composition of the present invention preferably has an average functional group number of 1.2 or less, more preferably 1.05 to 1.2. The present inventors have investigated the optimum number of reaction points and crosslink density in order to reduce curing shrinkage by reducing the number of reaction points in the entire system and ensure film strength by providing an appropriate crosslink structure. When the average functional group number of the polymerizable compound contained in the product is 1.2 or less, particularly 1.05 to 1.2, the effect of suppressing curing shrinkage of the film is high, and the adhesion of the film itself is greatly improved. It was found that the film strength can be maintained. As a result, adhesion to various substrates and coating films and film strength can be ensured.

In this specification, the average number of functional groups of the polymerizable compound contained in the ink composition can be calculated as follows.
Average functional group number=[total number of ethylenically unsaturated double bonds contained in polymerizable compound]/[total number of molecules in polymerizable compound] Formula (1)
Here, for the "total number of ethylenically unsaturated double bonds contained in the polymerizable compound" in the calculation formula (1), the number of ethylenically unsaturated double bonds per molecule of the polymerizable compound It is calculated by multiplying the total number of molecules of the chemical compound. When multiple types of polymerizable compounds are blended in the ink, the number of ethylenically unsaturated double bonds is calculated for each type, and the total number of ethylenically unsaturated double bonds is defined as To tell.
(Example of how to obtain the average number of functional groups of a polymerizable compound)
The total amount of the polymerizable compound is 100 parts by mass.
Polymerizable compound A: Number of ethylenically unsaturated double bonds = 1, molecular weight X _A , 30 parts by mass Polymerizable compound B: Number of ethylenically unsaturated double bonds = 2, molecular weight X _B , 70 parts by mass Average number of functional groups = {(1×30/X _A )+(2×70/X _B )}/{(30/X _A )+(70/X _B )}

It is useful to use a polyfunctional polymerizable compound having a large ethylenically unsaturated double bond equivalent in order to obtain an average functional group number of 1.05 to 1.2. The ethylenically unsaturated double bond equivalent is a value obtained by dividing the molecular weight by the number of ethylenically unsaturated double bonds contained in one molecule. When the ethylenically unsaturated double bond is derived from a (meth)acryloyl group, it is also called "acrylic equivalent". Generally, the larger this value, the wider the space between cross-linking points and the lower the cross-linking density. As a result, it can contribute to the reduction of curing shrinkage.

The polymerizable compound contained in the ink composition of the present invention preferably contains 55 to 80% by mass of a monofunctional polymerizable compound. Adhesiveness and flexibility can be improved as the amount of the monofunctional polymerizable compound is 55% by mass or more relative to the total polymerizable compound. In addition, if the ratio of the monofunctional polymerizable compound is too high, the film strength and the curability are lowered. More preferably, the amount of the monofunctional polymerizable compound with respect to the total polymerizable compound is 55 to 75% by mass.

The polymerizable compound contained in the ink composition of the present invention preferably contains 1 to 20% by weight, particularly 3 to 20% by weight of a bifunctional polymerizable compound having a molecular weight of 300 to 1,500. From the viewpoint of achieving both adhesion and curability, it is preferable to use a polymerizable compound having two functional groups exhibiting radical polymerizability (bifunctional polymerizable compound). Moreover, from the viewpoint of suppressing cure shrinkage, it is preferable to use a polymerizable compound having a relatively high molecular weight. More preferably, the amount of the bifunctional polymerizable compound having a molecular weight of 300 to 1500 is 5 to 20% by mass based on the total polymerizable compound.

In this specification, when the polymerizable compound is an oligomer, its molecular weight can be measured as a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography.

Bifunctional polymerizable compounds include bifunctional polymerizable monomers and bifunctional polymerizable oligomers. In the ink composition of the invention, the amount of the bifunctional polymerizable compound is preferably 3 to 20% by mass, more preferably 5 to 20% by mass.

The ink composition of the invention preferably contains a polymerizable compound having a heterocyclic skeleton. Curability can be improved by using a polymerizable compound having a heterocyclic skeleton. Moreover, the polymerizable compound having a heterocyclic skeleton is preferably a nitrogen-containing polymerizable compound, and more preferably a polymerizable compound in which the heterocyclic skeleton contains a nitrogen atom. In particular, a nitrogen-containing polymerizable compound as a polymerizable compound having a heterocyclic skeleton is highly effective in reducing polymerization inhibition due to oxygen during curing, and can improve the curability of the ink. In the ink composition of the invention, the amount of the polymerizable compound having a heterocyclic skeleton is preferably 1 to 10% by mass.

The ink composition of the invention preferably contains a polymerizable compound having a hydroxyl group. By using a polymerizable compound having a hydroxyl group, adhesion to a substrate and film strength can be improved by hydrogen bonding or chemical bonding via the hydroxyl group. In addition, like the polymerizable compound having a heterocyclic skeleton, it has the effect of reducing oxygen inhibition during curing, and an improvement in curability can be expected. In one embodiment of the present invention, the ink composition contains at least one of a polymerizable compound having a hydroxyl group and a silane compound described below, and preferably contains both the polymerizable compound having a hydroxyl group and the silane compound. In the ink composition of the invention, the amount of the polymerizable compound having a hydroxyl group is preferably 1 to 10% by mass.

〔式（１）中、ｎは１～３であり、Ｙはメトキシ基またはエトキシ基であり、ＲはＣ３より選ばれるアルキレン基であり、Ｚは（メタ）アクリロキシ基である。〕 The ink composition of the present invention preferably contains a polymerizable compound having a silicon atom, and more preferably contains a polymerizable compound represented by the following formula (1). Adhesion to the substrate can be improved by using a polymerizable compound having a silicon atom as the silane compound. In particular, the polymerizable compound represented by formula (1) is excellent in the effect of improving adhesion. In the ink composition of the invention, the amount of the polymerizable compound having a silicon atom is preferably 1 to 5% by mass.

[In the formula (1), n is 1 to 3, Y is a methoxy group or an ethoxy group, R is an alkylene group selected from C3, and Z is a (meth)acryloxy group. ]

The polymerizable compound contained in the ink composition of the present invention is P.I. I. I. It is preferred that the weighted average of the values be less than 2.00. P. I. I. is an abbreviation for Primary Irritation Index, which is translated as primary skin irritation index and the like.
The higher the primary skin irritation (P.I.I.), the more chemically irritating the skin, and the easier it is for symptoms such as rashes to occur. As such, it can be dangerous and cumbersome for the work environment and personnel. In addition, monomers with high primary skin irritation may remain in the coating film even after the curing process, which may pose a problem. Therefore, P.I. I. I. A safe ink design with low The Antimicrobial Product Technology Council (SIAA) cites as a safety standard that no irritation reaction is observed or that the degree of irritation is weak (P.I.I. (Primary Irritation Index): less than 2.00). It is
of the polymerizable compound contained in the ink composition. I. I. The method for obtaining the weighted average of the values is as follows.
Polymerizable compound A: P.I. I. I. = P _A , mass ratio = T _A
Polymerizable compound B: P.I. I. I. = P _B , mass ratio = T _B
P. I. I. Weighted average = P _A × T _A + P _B × T _B Calculation formula (2)

Specific examples of monofunctional polymerizable monomers include isoamyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, ) acrylate, stearyl (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, ethyl carbitol (meth) acrylate, 2-(2′-vinyloxyethoxy) ethyl (meth) ) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4- t-butylcyclohexyl (meth)acrylate, cyclohexyl (meth)acrylate, N-(meth)acryloylmorpholine, tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl) Methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, γ-butyrolactone (meth)acrylate, N-vinylcaprolactam, N-(meth)acryloyloxyethylhexahydrophthalimide, 1-(meth)acryloylpyrrolidine- 2-one, 1-(meth)acryloylpiperidin-2-one, N-vinyl-2-pyrrolidone, N-vinylimidazole, dimethylacrylamide, hydroxyethyl (meth)acrylamide, diethylacrylamide, isopropylacrylamide, dimethylaminopropyl (meth) ) acrylamide, diacetone acrylamide, Nn-butoxymethyl acrylamide, N-isobutoxymethyl acrylamide, N-methoxymethyl acrylamide, N-methylol acrylamide, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, benzyl (meth) ) acrylate, neopentyl glycol (meth) acrylic acid benzoate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, γ- (meth)acryloxypropyl Trimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyl Dipropoxysilane, γ-(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, γ-(meth)acryloxypropyldiethylmethoxysilane β-(meth)acryloxyethyltrimethoxysilane , β-(meth)acryloxyethyltriethoxysilane, polyoxyethylene mono(meth)acrylate, polyoxypropylene mono(meth)acrylate, polyoxybutylene mono(meth)acrylate, etc., and those modified with alkylene glycol is mentioned. Among these, a monofunctional polymerizable monomer having an extended alkyl chain or alkylene glycol chain is preferable because the odor is reduced due to the increase in molecular weight compared to before the chain extension.

Among polyfunctional polymerizable monomers, specific examples of polyfunctional polymerizable monomers having two functional groups exhibiting radical polymerizability (bifunctional polymerizable monomers) include 1,3-butylene glycol di(meth)acrylate, 1 ,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8 -octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 2-butyl-2 -ethyl-1,3-propanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, diethylene glycol di(meth)acrylate meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxy Neopentyl glycol pivalate di(meth)acrylate, PO (propylene oxide)-modified neopentyl glycol di(meth)acrylate, cyclohexanedimethanol diacrylate, tricyclodecanedimethanol diacrylate, dimethylol-tricyclodecane di(meth)acrylate , dicyclopentanyl diacrylate, bisphenol A di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate and the like.

Specific examples of polyfunctional polymerizable monomers having three or more functional groups exhibiting radical polymerizability (trifunctional or higher polyfunctional polymerizable monomers) include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri( meth)acrylates, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, EO-modified diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, EO-modified dipentaerythritol hexa(meth)acrylate, glycerin tri (Meth)acrylate and the like.

As used herein, the term (meth)acrylate means methacrylate or acrylate. For example, 2-hydroxyethyl (meth)acrylate is 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate. In addition, when a prefix indicating a plurality of (meth)acrylates such as di(meth)acrylate and tri(meth)acrylate is attached to each (meth)acrylate, each (meth)acrylate may be the same or different. good.

The polymerizable oligomer is preferably an acrylic oligomer. An acrylic oligomer is an oligomer having an acryloyl group or a methacryloyl group as a radically polymerizable functional group.

The polymerizable oligomer is preferably a polyfunctional polymerizable oligomer, more preferably a polyfunctional acrylic oligomer. The number of functional groups of the polymerizable oligomer is preferably 2-6, and the molecular weight of the polymerizable oligomer is preferably 800-20,000. The molecular weight of the polymerizable oligomer is the weight average molecular weight in terms of polystyrene.

Specific examples of acrylic oligomers include polyurethane acrylic oligomer [acrylic oligomer having multiple urethane bonds (-NHCOO-)], polyester acrylic oligomer [acrylic oligomer having multiple ester bonds (-COO-)], polyamino acrylic oligomer [amino group (-NH ₂ )], polyepoxy acrylic oligomer [acrylic oligomer having multiple epoxy groups], silicone acrylic oligomer [acrylic oligomer having multiple siloxane bonds (-SiO-)], polybutadiene acrylic oligomer [butadiene unit acrylic oligomer having a plurality of] and the like.

Further, the following are known as acrylic oligomers.
beam set 502H, beam set 505A-6, beam set 550B, beam set 575, beam set AQ-17 (manufactured by Arakawa Chemical Industries),
AH-600, UA-306H, UA-306T, UA-306I, UA-510H, UF-8001G (manufactured by Kyoeisha Chemical Co., Ltd.),
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U-2PPA, U-6LPA, U-10HA, U-10PA, UA-1100H, U-15HA, UA-53H, UA-33H, U-200PA, UA-200PA, UA-160TM, UA-290TM, UA- 4200, UA-4400, UA-122P (manufactured by Shin-Nakamura Chemical Co., Ltd.),
New Frontier R-1235, R-1220, RST-201, RST-402, R-1301, R-1304, R-1214, R-1302XT, GX-8801A, R-1603, R-1150D (Daiichi Kogyo Seiyaku Co., Ltd.) company),
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UV-1700B, UV-6300B, UV-7550B, UV-7600B, UV-7605B, UV-7610B, UV-7630B, UV-7640B, UV-7650B, UV-6630B, UV-7000B, UV-7510B, UV- 7461TE,
UV-2000B, UV-2750B, UV-3000B, UV-3200B, UV-3300B, UV-3310B, UV-3700B, UV6640B (manufactured by Nippon Synthetic Chemical Co., Ltd.),
Art resin UN-333, UN-350, UN-1255, UN-2600, UN-2700, UN-5590, UN-6060PTM, UN-6200, UN-6202, UN-6300, UN-6301, UN-7600, UN-7700, UN-9000PEP, UN-9200A, UN-3320HA, UN-3320HC, UN-904, UN-906S (manufactured by Negami Kogyo Co., Ltd.),
Aronix M-6100, M-6250, M-6500, M-7100, M-7300K, M-8030, M-8060, M-8100, M-8530, M-8560, M-9050 (manufactured by Toagosei Co., Ltd.)

Specific examples of polymerizable compounds having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6 - hydroxyhexyl (meth) acrylate, polyoxyethylene mono (meth) acrylate, polyoxypropylene mono (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, caprolactone-modified hydroxyethyl acrylate, etc. mentioned. In addition, polymerizable compounds having hydroxyl groups include polymerizable compounds that generate hydroxyl groups by thermal decomposition, such as N-methylolacrylamide. Moreover, the polymerizable compound having a hydroxyl group may be synthesized and used, or a commercially available product may be used.

Specific examples of polymerizable compounds having silicon atoms include γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, β-(meth)acryloxyethyltrimethoxysilane, β -(meth)acryloxyethyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ -(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, γ-(meth)acryloxypropyldiethylmethoxysilane and the like. Among these, the polymerizable compound represented by formula (1) includes γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyldimethylmethoxysilane, and the like. .

Specific examples of polymerizable compounds having a heterocyclic skeleton include N-acryloylmorpholine, N-methacryloylmorpholine, γ-butyrolactone (meth)acrylate, N-vinylcaprolactam, N-acryloyloxyethylhexahydrophthalimide, N-methacryloyloxy Ethylhexahydrophthalimide, 1-acryloylpyrrolidin-2-one, 1-methacryloylpyrrolidin-2-one, 1-acryloylpiperidin-2-one, 1-methacryloylpiperidin-2-one, N-vinyl-2-pyrrolidone, N -Vinylimidazole, tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, etc. be done. Among these, nitrogen content is good, and N-acryloylmorpholine is particularly preferred.

The photopolymerization initiator has the effect of initiating the polymerization of the polymerizable compound described above when irradiated with active energy rays. The amount of the photopolymerization initiator in the ink composition is preferably 1 to 15% by mass, more preferably 1 to 12% by mass, even more preferably 1 to 10% by mass. If the content of the polymerization initiator is less than 1% by mass, the film may be poorly cured, and if it exceeds 15% by mass, precipitates may occur at low temperatures, resulting in unstable ink ejection. Furthermore, in order to accelerate the initiation reaction of the polymerization initiator, it is also possible to use an auxiliary agent such as a photosensitizer together.

Examples of photopolymerization initiators include benzophenone-based compounds, acetophenone-based compounds, thioxanthone-based compounds, and acylphosphine oxide-based compounds. It is preferred that the wavelengths overlap as much as possible. In particular, the photopolymerization initiator preferably contains an acylphosphine oxide-based initiator from the viewpoint of coloring during curing and curability when forming a thick film. A photoinitiator may be used individually by 1 type, and may be used in combination of 2 or more types.

As for the photopolymerization initiator, it is preferable to use two or more initiators with different wavelength ranges. Thereby, the polymerizability of the compound can be improved. Further, by combining one with two cleavage points and one with one cleavage point, the starting radical concentration is increased, and the polymerizability and degree of curing can be improved.

As the acylphosphine oxide initiator, it is preferable to use a monoacylphosphine oxide initiator and a bisacylphosphine oxide initiator in combination. Here, the mass ratio (C:D) of the monoacylphosphine oxide initiator (C) and the bisacylphosphine oxide initiator (D) is particularly preferably 1:1 to 5:1.

Specific examples of photopolymerization initiators include:
2,2-dimethoxy-1,2-diphenylethan-1-one,
1-hydroxy-cyclohexyl-phenyl-ketone,
2-hydroxy-2-methyl-1-phenylpropan-1-one,
benzophenone,
1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one,
2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]-phenyl}-2-methyl-propan-1-one,
phenylglyoxylic acid methyl ester,
2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one,
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone,
2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one,
bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide,
bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide,
2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide,
1,2-octanedione, 1-[4-(phenylthio)-2-(O-benzoyloxime)],
Ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime),
2,4-diethylthioxanthone,
2-isopropylthioxanthone,
2-chlorothioxanthone and the like.

Among these, from the viewpoint of ink curability, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl -Phosphine oxide and 2,4-diethylthioxanthone are preferred, and from the viewpoint of coloring during curing and curability when thick, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis (2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide are preferred, 2,4,6-trimethylbenzoyl-diphenyl - phosphine oxides are particularly preferred.

〔式（２）中、ｎは１～３であり、Ｙはメトキシ基またはエトキシ基であり、ＲはＣ３より選ばれるアルキレン基であり、Ｘはグリシドキシ基またはエポキシシクロヘキシル基である。〕
なお、エポキシシクロヘキシル基とは、シクロヘキシル環を構成する２つの炭素原子と酸素原子でエポキシ基を形成しているシクロヘキシル基であり、エポキシ環とシクロヘキシル環の縮合環構造を有する基である。 The ink composition of the present invention preferably contains a silane coupling agent, and more preferably contains a silane coupling agent represented by the following formula (2). By using a silane coupling agent as the silane compound, adhesion to the substrate can be improved. In addition, the silane compound represented by formula (2) is also excellent in pigment dispersibility, and can improve the storage stability of the ink. The amount of the silane coupling agent in the ink composition of the invention is preferably 1 to 10% by mass. A silane coupling agent may be used individually by 1 type, and may be used in combination of 2 or more types.

[In the formula (2), n is 1 to 3, Y is a methoxy group or an ethoxy group, R is an alkylene group selected from C3, and X is a glycidoxy group or an epoxycyclohexyl group. ]
The epoxycyclohexyl group is a cyclohexyl group in which two carbon atoms and an oxygen atom constituting a cyclohexyl ring form an epoxy group, and is a group having a condensed ring structure of an epoxy ring and a cyclohexyl ring.

Specific examples of silane coupling agents include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, γ-glycid. xypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycidoxypropylmethyldimethoxysilane Cydoxypropyl(ethyl)dimethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, β-3,4-epoxycyclohexylethyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 8-glycidoxy Epoxy group-containing silane coupling agents such as octylmethyldimethoxysilane, 8-glycidoxyoctylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane , N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane isopropoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane Methoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-8-aminooctyltrimethoxysilane, γ-triethoxysilyl-N-(1,3-dimethyl-butylidene) Examples thereof include amino group-containing silane coupling agents such as propylamine.

Among these, silane coupling agents represented by formula (2) include γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethylmethoxysilane. etc.

The ink composition of the invention preferably contains a silane compound. By using a silane compound, the adhesion to the substrate and the dispersibility of the pigment can be improved. In one embodiment of the present invention, the ink composition contains at least one of the silane compound and the polymerizable compound having a hydroxyl group, and preferably contains both the silane compound and the polymerizable compound having a hydroxyl group. The amount of the silane compound in the ink composition of the invention is preferably 0.5 to 10% by mass. A silane compound may be used individually by 1 type, and may be used in combination of 2 or more types.

The silane compound includes, for example, a polymerizable compound having a silicon atom, preferably a polymerizable compound represented by formula (1), a silane coupling agent, preferably a silane coupling agent represented by formula (2), and the like. mentioned.

The ink composition of the present invention preferably contains, as a silane compound, at least one of a polymerizable compound represented by formula (1) and a silane coupling agent represented by formula (2). It is more preferable to contain both the polymerizable compound represented by formula (2) and the silane coupling agent represented by formula (2). When the polymerizable compound represented by the formula (1) and the silane coupling agent represented by the formula (2) are used in combination, the polymerizable compound represented by the formula (1) (E) and the formula (2) The mass ratio (E:F) to the silane coupling agent (F) used is particularly preferably 1:2 to 2:1.

The ink composition of the present invention may contain a coloring material such as a dye or a pigment, but in that case, it preferably contains a pigment, particularly an inorganic pigment, from the viewpoint of weather resistance. The content of the coloring material is, for example, 1 to 20% by mass in the ink composition. The coloring materials may be used singly or in combination of two or more.

Specific examples of coloring materials include:
C. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 14, 15, 16, 17, 24, 32, 34, 35, 36, 37, 41, 42, 43, 49, 53, 55, 60, 61, 62, 63, 65, 73, 74, 75, 77, 81, 83, 87, 93, 94, 95, 97, 98, 99, 100, 101, 104, 105, 106, 108, 109, 110, 111, 113, 114, 116, 117, 119, 120, 123, 124, 126, 127, 128, 129, 130, 133, 138, 139, 150, 151, 152, 153, 154, 155, 165, 167, 168, 169, 170, 172, 173, 174, 175, 176, 179, 180, 181, 182, 183, 184, 185, 191, 193, 194, 199, 205, 206, 209, 212, 213, 214, 215, 219,
C. I. Pigment Orange 1, 2, 3, 4, 5, 13, 15, 16, 17, 19, 20, 21, 24, 31, 34, 36, 38, 40, 43, 46, 48, 49, 51, 60, 61, 62, 64, 65, 66, 67, 68, 69, 71, 72, 73, 74, 81,
C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 21, 22, 23, 31, 32, 38, 41, 48, 48:1, 48:2, 48:3, 48:4, 48:5, 49, 52, 52:1, 52:2, 53:1, 54, 57:1, 58, 60:1, 63, 64:1, 68, 81:1, 83, 88, 89, 95, 101, 104, 105, 108, 112, 114, 119, 122, 123, 136, 144, 146, 147, 149, 150, 164, 166, 168, 169, 170, 171, 172, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 187, 188, 190, 193, 194, 200, 202, 206, 207, 208, 209, 210, 211, 213, 214, 216, 220, 220, 221, 224, 226, 237, 238, 239, 242, 245, 247, 248, 251, 253, 254, 255, 256, 257, 258, 260, 262, 263, 264, 266, 268, 269, 270, 271, 272, 279,
C. I. Pigment Violet 1, 2, 3, 3:1, 3:3, 5:1, 13, 15, 16, 17, 19, 23, 25, 27, 29, 31, 32, 36, 37, 38, 42, 50,
C. I. Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, 16, 17:1, 24, 24:1, 25, 26, 27, 28, 29, 36, 56, 60, 61, 62, 63, 75, 79, 80,
C. I. Pigment Green 1, 4, 7, 8, 10, 15, 17, 26, 36, 50,
C. I. Pigment Brown 5, 6, 23, 24, 25, 32, 41, 42,
C. I. Pigment Black 1, 6, 7, 9, 10, 11, 20, 26, 28, 31, 32, 34,
C. I. Pigment White 1, 2, 4, 5, 6, 7, 11, 12, 18, 19, 21, 22, 23, 26, 27, 28,
Examples include aluminum flakes, glass flakes, pearl pigments and hollow particles.

Among these, from the viewpoint of weather resistance and color reproducibility of the obtained film,
C. I. Pigment Black 7,
C. I. Pigment Blue 15:3, C.I. I. Pigment Blue 15:4, C.I. I. Pigment Blue 28,
C. I. Pigment Red 101, C.I. I. Pigment Red 122, C.I. I. Pigment Red 202, C.I. I. Pigment Red 254, C.I. I. Pigment Red 282,
C. I. Pigment Violet 19,
C. I. Pigment White 6,
C. I. Pigment Yellow 42, C.I. I. Pigment Yellow 120, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 139, C.I. I. Pigment Yellow 150, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 155, C.I. I. Pigment Yellow 184, C.I. I. Pigment Yellow 213 is preferred.

The ink composition of the present invention may further contain a pigment dispersant as necessary to disperse the pigment. The content of the pigment dispersant is, for example, 0.1 to 5% by mass in the ink composition. Pigment dispersants may be used singly or in combination of two or more.

Specific examples of pigment dispersants include:
ANTI-TERRA-U, ANTI-TERRA-U100,
ANTI-TERRA-204, ANTI-TERRA-205,
DISPERBYK-101, DISPERBYK-102,
DISPERBYK-103, DISPERBYK-106,
DISPERBYK-108, DISPERBYK-109,
DISPERBYK-110, DISPERBYK-111,
DISPERBYK-112, DISPERBYK-116,
DISPERBYK-130, DISPERBYK-140,
DISPERBYK-142, DISPERBYK-145,
DISPERBYK-161, DISPERBYK-162,
DISPERBYK-163, DISPERBYK-164,
DISPERBYK-166, DISPERBYK-167,
DISPERBYK-168, DISPERBYK-170,
DISPERBYK-171, DISPERBYK-174,
DISPERBYK-180, DISPERBYK-182,
DISPERBYK-183, DISPERBYK-184,
DISPERBYK-185, DISPERBYK-2000,
DISPERBYK-2001, DISPERBYK-2008,
DISPERBYK-2009, DISPERBYK-2020,
DISPERBYK-2025, DISPERBYK-2050,
DISPERBYK-2070, DISPERBYK-2096,
DISPERBYK-2013, DISPERBYK-2150,
DISPERBYK-2155, DISPERBYK-2163,
DISPERBYK-2164,
BYK-P104, BYK-P104S, BYK-P105,
BYK-9076, BYK-9077, BYK-220S, BYKJET-9150, BYKJET-9151 (manufactured by BYK-Chemie Japan),
Solsperse 3000, Solsperse 5000,
Solsperse 9000, Solsperse 11200,
Solsperse 13240, Solsperse 13650,
Solsperse 13940, Solsperse 16000,
Solsperse 17000, Solsperse 18000,
Solsperse 20000, Solsperse 21000,
Solsperse 24000SC, Solsperse 24000GR,
Solsperse 26000, Solsperse 27000,
Solsperse 28000, Solsperse 32000,
Solsperse 32500, Solsperse 32550,
Solsperse 32600, Solsperse 33000,
Solsperse 34750, Solsperse 35100,
Solsperse 35200, Solsperse 36000,
Solsperse 36600, Solsperse 37500,
Solsperse 38500, Solsperse 39000,
Solsperse 41000, Solsperse 54000,
Solsperse 55000, Solsperse 56000,
Solsperse 71000, Solsperse 76500,
Solsperse J180, Solsperse J200,
Solsperse X300 (manufactured by Lubrizol),
Disparlon DA-7301, Disparlon DA-325, Disparlon DA-375, Disparlon DA-234 (manufactured by Kusumoto Kasei Co., Ltd.),
Floren AF-1000, Floren DOPA-15B, Floren DOPA-15BHFS, Floren DOPA-17HF, Floren DOPA-22, Floren DOPA-33, Floren G-600, Floren G-700, Floren G-700AMP, Floren G-700DMEA, Floren G-820, Floren G-900, Floren GW-1500, Floren KDG-2400, Floren NC-500, Floren WK-13E (manufactured by Kyoeisha Chemical Co., Ltd.),
TEGO Dispers610, TEGO Dispers610S,
TEGO Dispers 630, TEGO Dispers 650,
TEGO Dispers 652, TEGO Dispers 655,
TEGO Dispers662C, TEGO Dispers670,
TEGO Dispers 685, TEGO Dispers 700,
TEGO Dispers710, TEGO Dispers740W,
LIPOTIN A, LIPOTIN BL,
LIPOTIN DB, LIPOTIN SB (manufactured by Evonik Degussa),
PB821, PB822, PN411, PA111 (manufactured by Ajinomoto Fine-Techno Co., Inc.),
Texahall 963, Texahall 964, Texahall 987, Texahall P60, Texahall P61, Texahall P63, Texahall 3250, Texahall SF71, Texahall UV20, Texahall UV21 (manufactured by Cognis),
BorchiGenSN88, BorchiGen0451 (above, manufactured by Bosius) and the like.

The ink composition of the present invention may further contain a surface modifier from the viewpoint of improving wettability. As used herein, a surface modifier means a substance that has a hydrophilic site and a hydrophobic site in its molecular structure and that can be added to adjust the surface tension of the ink composition.

Specific examples of surface modifiers that can be used in the ink composition of the present invention include anionic surface modifiers such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene nonionic surface conditioners such as alkylallyl ethers, acetylene glycols, and polyoxyethylene/polyoxypropylene block copolymers; cationic surface conditioners such as alkylamine salts and quaternary ammonium salts; acrylic surface conditioners; Examples include silicon-based surface conditioners and fluorine-based surface conditioners. In particular, silicon-based surface conditioners and acrylic-based surface conditioners are preferred, and commercially available products such as BYK-Chemie, Evonik, and Dow Corning Toray can be used. Furthermore, in the case of a silicone-based surface conditioner, it is preferably a polyether-modified silicone oil and has an HLB of 7.6 to 12.

The amount of the surface modifier can be appropriately selected depending on the purpose of use, but is preferably 0.01 to 1% by mass in the ink composition, for example. The surface conditioners may be used singly or in combination of two or more.

Specific examples of surface conditioners include:
BYK-300, BYK-302, BYK-306, BYK-307, BYK-310, BYK-313, BYK-315N, BYK-320, BYK-322, BYK-323, BYK-325, BYK-326, BYK- 330, BYK-331, BYK-333, BYK-342, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-350, BYK-354, BYK-355, BYK-356, BYK-358N, BYK-361N, BYK-370, BYK-375, BYK-377, BYK-378, BYK-381, BYK-392, BYK-394, BYK-399, BYK-3440, BYK-3441, BYK- 3455, BYK-3550, BYK-3560, BYK-3565, BYK-3760, BYK-DYNWET 800N, BYK-SILCLEAN 3700, BYK-SILCLEAN 3701, BYK-SILCLEAN 3720, BYK-UV3500, BYK-UV3503, BYK-UV10YK- BYK-UV3530, BYK-UV3535, BYK-UV3570, BYK-UV3575, BYK-UV3576 (manufactured by BYK-Chemie Japan),
ＴＥＧＯ Ｆｌｏｗ ３００、ＴＥＧＯ Ｆｌｏｗ ３７０、ＴＥＧＯ Ｆｌｏｗ ４２５、ＴＥＧＯ Ｆｌｏｗ ＡＴＦ ２、ＴＥＧＯ Ｆｌｏｗ ＺＦＳ ４６０、ＴＥＧＯ Ｇｌｉｄｅ １００、ＴＥＧＯ Ｇｌｉｄｅ １１０、ＴＥＧＯ Ｇｌｉｄｅ １３０、ＴＥＧＯ Ｇｌｉｄｅ ４０６、ＴＥＧＯ Ｇｌｉｄｅ ４１０、ＴＥＧＯ Ｇｌｉｄｅ ４１１、ＴＥＧＯ Ｇｌｉｄｅ ４１５、 TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Glide 482, TEGO Glide A 115, TEGO Glide B 1484, TEGO Glide ZG 400 (manufactured by Evonik Japan),
501W ADDITIVE, FZ-2104, FZ-2110, FZ-2123, FZ-2164, FZ-2191, FZ-2203, FZ-2215, FZ-2222, FZ-5609, L-7001, L-7002, L-7604 , OFX-0193, OFX-0309 FLUID, OFX-5211 FLUID, SF 8410 FLUID, SH3771, SH 3746 FLUID, SH 8400 FLUID, SH 8700 FLUID, Y-7006 (manufactured by Dow Corning Toray Co., Ltd.),
KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-640, KF-642, KF-643, KF-644, KF-945, KF-6004, KF- 6011, KF-6012, KF-6015, KF-6017, KF-6020, KF-6204, X-22-2516, X-22-4515 (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

The ink composition of the invention may contain an ultraviolet absorber. The ultraviolet absorber has the action of absorbing ultraviolet rays and preventing deterioration due to ultraviolet rays. Examples of ultraviolet absorbers include cyanoacrylate compounds, benzophenone compounds, benzoate compounds, benzotriazole compounds, hydroxyphenyltriazine compounds, benzylidene camphor compounds, inorganic fine particles, and the like.

Specific examples of UV absorbers include:
2,4-dihydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone,
2-hydroxy-4-methoxybenzophenone-5-sulfonic acid,
2-hydroxy-4-octoxybenzophenone,
2-hydroxy-4-dodecyloxybenzophenone-2-hydroxy-4-benzyloxybenzophenone,
bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane,
2,2′-dihydroxy-4-methoxybenzophenone,
2,2′-dihydroxy-4,4′-dimethoxybenzophenone,
2,2′,4,4′-tetrahydroxybenzophenone,
2-hydroxy-4-methoxy-2'-carboxybenzophenone,
2-(2'-hydroxy-5'-methylphenyl)benzotriazole 2-[2'-hydroxy-3',5'-bis(α,α-(dimethylbenzyl)phenyl]benzotriazole,
2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole,
2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole,
2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole,
2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole,
2-(2′-hydroxy-5′-t-octylphenyl)benzotriazole,
2,2′-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-(2N-benzotriazol-2-yl)phenol],
condensation products of methyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate and polyethylene glycol;
2-(2-hydroxyphenyl)benzotriazole,
2-(2′-hydroxy-5′-methylphenyl)benzotriazole,
2,6-di-t-butylphenyl-3′,5′-di-t-butyl-4′-hydroxybenzoate,
hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate and the like.

In the ink composition of the present invention, the amount of the ultraviolet absorber is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 to 5% by mass. . If the amount of UV absorber is too high, the film may not cure sufficiently. The UV absorbers may be used singly or in combination of two or more, but the UV absorbers preferably contain at least two UV absorbers. By using a plurality of types of ultraviolet absorbers having different structures, the effects of the ultraviolet absorbers can be maintained longer.

The ink composition of the invention may contain a radical scavenger. A radical scavenger can scavenge free radicals and the like to improve photostability. Radical scavengers also include substances that react with free radicals and have the function of preventing polymerization reactions (so-called polymerization inhibitors).

Examples of radical scavengers include hindered amine compounds, hydroquinone compounds, phenol compounds, phenothiazine compounds, nitroso compounds, N-oxyl compounds, etc. Hindered amine light stabilizers (HALS) are particularly preferred.

Specific examples of radical scavengers include bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1-{2-(3-(3,5-di-t-butyl-4- hydroxyphenyl)propionyloxy)ethyl}-2,2,6,6-tetramethylpiperidine, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro {4. 5} Hindered amine compounds such as decane-2,4-dione, phenol, o-, m- or p-cresol, 2-t-butyl-4-methylphenol, 6-t-butyl-2,4-dimethylphenol , 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4- Phenolic compounds such as t-butyl-2,6-dimethylphenol, hydroquinone, hydroquinone monomethyl ether, methylhydroquinone, 2,5-di-t-butylhydroquinone, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone , trimethylhydroquinone 4-methylbenzcatechin, t-butylhydroquinone, 3-methylbenzcatechin, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, benzoquinone, t-butyl-p -benzoquinone, hydroquinone compounds such as 2,5-diphenyl-p-benzoquinone, phenothiazine compounds such as phenothiazine, N-nitroso-N-phenylhydroxylamine ammonium, nitroso such as N-nitroso-N-phenylhydroxylamine aluminum salt compound, 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-methoxy-2 , 2,6,6-tetramethyl-piperidine-N-oxyl and other N-oxyl compounds.

In the ink composition of the present invention, the amount of the radical scavenger is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less. Too much radical scavenger may cause poor curing. The lower limit of the content of the radical scavenger is, for example, 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. A radical scavenger may be used individually by 1 type, and may be used in combination of 2 or more types.

The ink composition of the invention may contain a resin. The resin has a role of capturing solid components such as pigments and forming a film on the base material, and contributes to improving the adhesion of the ink composition to the base material.

Specific examples of resins include polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride resin, chlorinated rubber, chlorinated polyethylene resin, chlorinated polypropylene resin, chlorinated ethylene-vinyl acetate resin, acrylic resin, and polystyrene resin. , Polyamide resin, polyurethane resin, polyolefin resin, silicone resin, fluorine resin, epoxy resin, polyester resin, ketone resin, phenol resin, polyvinyl alcohol, polyvinyl alcohol derivatives (anion-modified polyvinyl alcohol, etc.), cellulose, cellulose derivatives (hydroxymethyl cellulose, hydroxyethyl cellulose, cellulose acetate, etc.), rosin-based resins, alkyd resins, alginic acid, alginic acid derivatives (propylene glycol alginic acid, etc.), and the like. Modified products of these resins are also included. For example, in the case of a resin having a hydroxyl group, modifications such as hydroxyalkyl ether modification and carboxylic acid modification can be mentioned.

In the ink composition of the present invention, the amount of resin is preferably 25% by mass or less, particularly 10% by mass or less, and more preferably 8% by mass or less. Too much resin may cause poor curing. The lower limit of the resin content is, for example, 1% by mass or more, preferably 3% by mass or more. The resin may be used singly or in combination of two or more.

Other components of the ink composition of the present invention include antioxidants, plasticizers, rust inhibitors, solvents, antibacterial agents, antiviral agents, viscosity modifiers, fillers, antifoaming agents, charge control agents, and stress relaxation agents. Additives such as agents, penetrating agents, light guide materials, luster materials, magnetic materials, and phosphors may be used as necessary.

The ink composition of the present invention can be prepared by mixing various components appropriately selected as necessary. In addition, it is preferable to filter the ink composition using a filter for the purpose of preventing nozzle clogging of the head due to impurities or the like.

The ink composition of the present invention preferably has a viscosity at 40° C. of 5 to 25 mPa·s, more preferably 5 to 20 mPa·s. If the ink viscosity at 40° C. is within the specified range, good ejection stability can be obtained. Ink viscosity can be measured using a cone-plate viscometer. The temperature at which the ink is ejected is preferably 30.degree. C. to 50.degree.

The ink composition of the present invention preferably has a surface tension at 25° C. of 20 to 35 mN/m, more preferably 23 to 33 mN/m. If the surface tension of the ink at 25° C. is within the specified range, good ejection stability can be obtained. Ink surface tension can be measured by the plate method.

Printing with the ink composition of the present invention is performed by an inkjet printing method. For inkjet printing, various inkjet printers can be used. Examples of inkjet printers include inkjet printers that eject an ink composition by a charge control method or a piezo method. In addition, a large-sized inkjet printer, as a specific example, an inkjet printer for the purpose of printing on articles produced on an industrial line can also be suitably used.

A layer formed by printing using the ink composition of the present invention is cured by irradiation with active energy rays such as ultraviolet rays. A high-pressure mercury lamp, a metal halide lamp, an LED lamp, or the like can be used as a light source for active energy rays. The wavelength of the active energy ray irradiated to cure this layer preferably overlaps with the absorption wavelength of the photopolymerization initiator, and the dominant wavelength of the active energy ray is preferably 350 to 400 nm. It is preferable that the integrated amount of active energy rays is in the range of 100 to 2000 mJ/cm ² .

The ink composition of the present invention can be subjected to surface finishing such as gloss tone and matte tone by appropriately selecting ejection conditions for inkjet printing and subsequent curing conditions. For example, if the ink composition spreads and then cures after a period of time, it will have a gloss finish, and if the ink droplets remain in the form of a lens and harden, it will have a matte finish.

The substrate to be printed with the ink composition of the present invention is not particularly limited, and examples thereof include paper, coated paper, plastic materials, building boards and the like. The shape of the substrate includes, for example, a film shape, a sheet shape, a plate shape, and the like. Examples of materials for the substrate include plastics such as epoxy resin, ABS resin, polycarbonate, polyvinyl chloride, polystyrene, acrylic resin, particularly polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polypropylene (PP), etc. Metals such as iron, stainless steel, aluminum, copper, titanium and their alloys, wood, cement, concrete, gypsum, calcium silicate, calcium carbonate, marble, artificial marble, glass, ceramics, etc., and two of these materials. A combination of the above may also be used. The surface of the base material may be subjected to pretreatment such as degreasing treatment, chemical conversion treatment, polishing, sealer, primer coating, or the like. The substrate surface may be smooth, uneven, or three-dimensional. Specific examples of the base material include plastic materials such as vinyl chloride sheets, tarpaulin, plastic cardboard (plastic cardboard), and acrylic plates; coated paper (specifically, resin-coated paper), art paper, cast paper, lightly coated paper, Wood-based building materials such as veneer, plywood, particle board, and medium density fiberboard (MDF); ceramic siding boards, flexible boards, calcium silicate boards, Inorganic building materials such as gypsum slag barite board, wood chip cement board, pulp cement board, precast concrete board, lightweight aerated concrete (ALC) board, gypsum board; metal building materials such as aluminum, iron and stainless steel, tiles, glass boards, etc. be done.

The base material may have a layer (for example, a coating film or a printed film) formed on part or the entire surface thereof. For example, a coating film formed of paint, a printed film formed of ink, a printed film formed of powder toner, or the like may be formed on the substrate. The layer formed on the base material includes resins, coloring materials such as dyes and pigments, ultraviolet absorbers, radical scavengers, antioxidants, plasticizers, rust inhibitors, fillers, charge control agents, light guide materials, Luminescent materials, magnetic materials, phosphors, waxes, and the like can be included.

Paints and inks used to form a layer on a substrate include organic solvent-based paints and inks using organic solvents as the main solvent, water-based paints and inks using water as the main solvent, and light-based paints using polymerizable compounds. Various paints and inks such as curable paints and inks, powder paints, and the like are included. Here, the components that can be used in the case of the photocurable ink include the components that can be used in the ink composition of the present invention described above.

A means for forming a layer on a substrate is not particularly limited. For example, in the case of paint, various coating means such as air spray, airless spray, roll coater, flow coater and electrostatic coating can be used. In the case of ink, various printing means such as gravure printing, offset printing, flexographic printing, screen printing, coater printing, and inkjet printing can be used. In the case of a powder toner, an electrophotographic printing means (specifically, an image forming apparatus such as a copying machine or a laser printer) can be used.

Another layer (for example, a coating film or a printed film) may be formed on the layer formed by printing using the ink composition of the present invention. For example, a coating film formed of paint, a printed film formed of ink, or the like may be formed. Other layers that can be placed on the layer formed from the ink composition of the present invention include resins, colorants such as dyes and pigments, ultraviolet absorbers, radical scavengers, antioxidants, plasticizers, antirust agents, Anti-algae agents, anti-mold agents, antibacterial agents, antiviral agents, fillers, charge control agents, light guide materials, luster materials, magnetic materials, phosphors, waxes, and the like can be included.

As paints and inks used to form another layer on the layer formed from the ink composition of the present invention, organic solvent-based paints and inks using an organic solvent as the main solvent and water as the main solvent are used. Water-based coatings and inks, photocurable coatings and inks using polymerizable compounds, various coatings and inks such as powder coatings, and the like can be mentioned. Here, the components that can be used in the case of the photocurable ink include the components that can be used in the ink composition of the present invention described above.

A means for forming another layer on the layer formed from the ink composition of the present invention is not particularly limited. For example, in the case of paint, various coating means such as air spray, airless spray, roll coater, flow coater and electrostatic coating can be used. In the case of ink, various printing means such as gravure printing, offset printing, flexographic printing, screen printing, coater printing, and inkjet printing can be used.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

An inkjet ink was prepared by obtaining a mixture according to the formulations shown in Tables 1 to 7, kneading it in a bead mill to homogenize it, and filtering it using a filter.
The evaluation results of the obtained inkjet ink are shown in Table 8.

Notes in the table are as follows.
a) Caprolactone-modified hydroxyethyl acrylate Plaxel FA2D
(manufactured by Daicel Allnex)
b) Aminoacrylate EBECRYL 7100 (manufactured by Daicel Allnex)
c) Aliphatic urethane acrylate EBECRYL 8402
(manufactured by Daicel Allnex)
d) Pigment dispersant BYKJET-9151 (manufactured by BYK-Chemie Japan)
In addition, in the item of "the number of ethylenically unsaturated double bonds (A) = 1, (B) ≥ 2 (B)/(A)" in the table, the monofunctional polymerizable compound contained in the ink composition The B/A value is shown where A is the amount (% by mass) of and B is the amount (% by mass) of the polyfunctional polymerizable compound contained in the ink composition. The item "ink composition PII value" in the table shows the P.I.I. value of the polymerizable compound contained in the ink composition. I. I. A weighted average of the values is shown.

Evaluation methods and evaluation criteria for curability, adhesiveness, and pencil hardness are described below.
An ink composition that exhibits favorable evaluation results in all of curability, adhesiveness, and pencil hardness can be said to be practical.

<Curability>
After the ink composition was applied onto the acrylic resin substrate using a bar coater #5, it was cured by irradiation with active energy rays, and the curability of the ink was evaluated. Using a metal halide lamp as a light source, 100 mJ/cm ² of active energy rays with a dominant wavelength of 360 to 425 nm were irradiated, and then the cured ink film was wiped dry with a waste cloth. It was visually confirmed whether there was any color transfer to the waste cloth, and the above irradiation and dry wiping were repeated until no color transfer occurred. Curing of the ink composition was considered to be completed when there was no color transfer, and the curability was evaluated based on the cumulative amount of light required until completion. Evaluation criteria are as follows. Table 8 shows the results. In practical terms, an evaluation result of Δ or higher is preferable, an evaluation result of ◯ or higher is more preferable, and an evaluation result of ⊚ indicates that the ink composition has extremely high curability.
A: No color transfer at 100 mJ/cm ² .
◯: No color transfer at 200 mJ/cm ² .
Δ: No color transfer at 300 to 1000 mJ/cm ² .
x: Color transfer occurs even when irradiated at 1000 mJ/cm ² or more (does not cure completely).

<Adhesion>
A cured film of the ink was prepared in the same manner as in the above curability test, and adhesion was evaluated. As the base material, in addition to an acrylic resin base material, polycarbonate, ABS resin, and polyvinyl chloride base materials were used. The adhesion test was conducted according to JIS K-5600-1-6 and evaluated according to the following criteria. Table 8 shows the results. The smaller the number, the higher the grade. The grade of 2 or more indicates a level sufficiently suitable for practical use. The grade of 1 is more preferable, and the ink composition of 0 has high adhesiveness. It can be said.
0: The edges of the cut are perfectly smooth, and no peeling occurs on any grid mesh.
1: Small delamination of coating at intersection of cuts. The crosscut part is affected by clearly no more than 5%.
2: The coating is peeling along the edges of the cut and/or at the intersections. The crosscut portion is clearly affected by more than 5%, but not more than 15%.
3: The coating is partially or totally detached along the edge of the cut and/or is partially or totally detached in various parts of the eye. The cross-cut part is affected clearly more than 15%, but not more than 35%.
4: The coating film is partially or wholly peeled off along the edge of the cut, and/or partially or wholly peeled off at several spots. No more than 65% are clearly affected in the crosscut portion.
5: Some degree of peeling that cannot be classified even in Class 4.

<Pencil hardness>
The cured ink film obtained by the verification of <curability> was evaluated for pencil hardness by scratch hardness (pencil method) according to JIS K-5600-5-4. Table 8 shows the results. F or more is preferable, and if it is H or more, it can be said that the ink composition has high film strength.

Claims (5)

A silane compound and / or a polymerizable compound having a hydroxyl group, a polymerizable compound having a heterocyclic skeleton, and a photopolymerization initiator,
When A is the amount (% by mass) of the monofunctional polymerizable compound contained in the ink composition and B is the amount (% by mass) of the polyfunctional polymerizable compound contained in the ink composition, 0.03≦ An inkjet ink composition, wherein B/A≦0.30 and 50% by mass≦A+B≦95% by mass. 2. The inkjet ink composition of claim 1, wherein the polymerizable compound contained in the ink composition has an average functional group number of 1.2 or less. 3. The inkjet ink composition according to claim 1, wherein the polymerizable compound having a heterocyclic skeleton is a nitrogen-containing polymerizable compound. 1. The polymerizable compound contained in the ink composition contains 1 to 20% by mass of a bifunctional polymerizable compound having a molecular weight of 300 to 1,500 and 55 to 80% by mass of a monofunctional polymerizable compound. 4. The inkjet ink composition according to any one of 1 to 3. P. in the polymerizable compound contained in the ink composition. I. I. 5. The inkjet ink composition of any one of claims 1 to 4, wherein the weighted average of the values is less than 2.00.