JP2007137923A - Cationic curable reactive diluent, colorant dispersion, inkjet ink, and printed matter using the inkjet ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cationic curable reactive diluent and an ink-jet ink having high safety while maintaining dilution performance and curing performance.
A cationic curable reactive diluent containing a vinyl ether compound and limonene dioxide as an acid polymerizable compound that polymerizes in the presence of an acid. Furthermore, a colorant dispersion in which a color component is blended with the cationic curing type reactive diluent. An ink-jet ink containing the colorant dispersion and a photoacid generator, an epoxy compound, a photosensitizer, a thickener and the like.
[Selection figure] None

Description

  The present invention relates to a cationic curable reactive diluent, a colorant dispersion, an inkjet ink, and a printed matter using the inkjet ink.

  Epoxy resins are used in a wide range of fields such as paints, printing inks, semiconductor-related sealants, and adhesives. Among epoxy resins, a typical one is a bisphenol A type epoxy resin, and various resins using bisphenol A as a raw material have been made and used according to each application. Even if this bisphenol A type epoxy resin is of a relatively low molecular weight type, it has a high viscosity of about 10000 mPa · s at room temperature, and is usually handled with an appropriate viscosity adjusted using a diluent.

  Diluents are roughly classified into reactive diluents and non-reactive diluents (organic solvents). Diluents are required to have low viscosity and a diluting effect, good drying (curing) properties, high safety, low odor, low flammability, and the like. Since reactive diluents have a low environmental load, application to various uses has been attempted, and various reactive diluents have been proposed.

  Typical reactive diluents include various monoepoxy compounds and glycidyl ethers of polyhydric alcohols, and butyl glycidyl ether (BGE) has been mainly used. BGE has a high dilution performance capable of adjusting the viscosity with a small amount of addition, and a certain degree of curing performance can be obtained. For example, the toxicity of BGE is low as compared with low molecular diluents such as methyl glycidyl ether and allyl glycidyl ether. However, in general, glycidyl ethers have a big problem with respect to toxicity centering on mutagenicity, and most compounds are positive in a test using Salmonella. BGE is also toxic, and a compound with reduced toxicity has been proposed (for example, see Patent Document 1). However, such a compound has a trade-off relationship between toxicity and reactivity, and is difficult to achieve both. .

  A reactive diluent having a low chlorine content, an excellent dilution effect, and a small decrease in physical properties such as Tg has been proposed (see, for example, Patent Document 2). In addition, a reactive diluent that gives a coating film having low viscosity and excellent corrosion resistance, chemical resistance, curability, and adhesion has been proposed (see, for example, Patent Document 3). However, these compounds still have problems with mutagenicity.

  Aliphatic epoxy compounds are known as relatively safe reactive diluents. Among them, an epoxy compound obtained using a natural product skeleton such as a terpene as a starting material tends to be much less mutagenic than the glycidyl ether compound described above. Specific examples include limonene dioxide, but such compounds are actually positive in the mutagenicity test and still have problems in distribution and processing.

  Conventionally, printing presses using plates have been used to produce printed materials that require a certain number of copies, such as regional advertisements, corporate distribution materials, and large posters. In recent years, on-demand printing presses capable of quickly responding to diversifying needs and capable of compressing inventory are being used in place of such conventional printing presses. As such an on-demand printer, an electrophotographic printer using toner or liquid toner and an inkjet printer capable of high-speed and high-quality printing are expected.

  On-demand printing machines use solvent-based inks and solvent-based liquid toners containing pigments and organic solvents, as with printing machines that use plates. In this technique, when a certain number of copies are printed, a non-negligible amount of organic solvent volatilizes. Therefore, there is a problem of atmospheric pollution due to the volatilized organic solvent, and an exhaust facility and a solvent recovery mechanism must be provided.

  On the other hand, in an ink jet printer, solvent-based ink can be handled in a closed system until it is discharged onto a printing surface. Therefore, the problem of atmospheric pollution can be reduced to some extent by taking appropriate exhaust measures. However, unlike ink used in a printing machine using a plate, ink used in an ink jet printer must have fluidity necessary for ejection. Therefore, the ink used must have a sufficiently high solvent concentration, and even with this technique, it is essentially difficult to solve the problem of atmospheric contamination caused by organic solvents.

  In addition, when solvent-based ink is used, the printing surface has a great influence on the image quality. For example, bleeding tends to occur on a permeable printing surface, and fixing of an image is difficult on a non-permeable printing surface. Furthermore, since it takes a certain amount of time for the ink layer formed on the printing surface to dry, when a dark image is formed on a wide printing surface, the ink layer is liable to be crushed due to its fluidity. In addition, when solvent-based ink is used, the printing surface may be deteriorated as the ink layer is dried. That is, it is not always easy to obtain a high-quality printed matter with this technique.

  As an effective technique for the solvent problem, photosensitive ink and a printer system using the same have begun to attract attention. The photosensitive ink used is typically one containing a radically polymerizable monomer, a photopolymerization initiator, and a pigment (see, for example, Patent Document 4 and Patent Document 5), and was discharged onto the printing surface. The photosensitive ink is quickly photocured.

  According to this technique, since the ink layer can be made non-fluidized by light irradiation, a printed matter having a relatively high quality can be obtained. However, the photosensitive ink contains many carcinogenic components such as a radical generator, and the volatile acrylic acid derivative used as the radical polymerizable monomer has a large skin irritation and odor. That is, such photosensitive ink requires attention in handling. Furthermore, radical polymerization is significantly inhibited by the presence of oxygen in the air, and exposure light is absorbed by the pigment contained in the ink. As a result, since the exposure amount tends to be insufficient at the deep part of the ink layer, the conventional radical polymerizable ink has low sensitivity to light. Therefore, in order to obtain a high-quality printed matter with this technique, a very large exposure system is required.

  As an ink having a relatively small influence of oxygen, a photo-cation polymerizable photosensitive ink has been proposed (for example, see Patent Document 6). However, since this type of conventional ink contains a solvent, the problem of solvent release to the environment is inevitable. In addition, the cured product is easily cured, and the head is easily clogged because it is insoluble. Further, a cationic curable photosensitive composition for coating CD-ROM that can be ejected by inkjet has been proposed (see, for example, Patent Document 7). The composition that can be actually ejected by ink jet is mainly composed of vinyl ether and bisphenol A type epoxy having a carcinogenicity problem, and the problem of release to the environment is also great.

  Furthermore, an inkjet ink containing a cationic curable monomer having a specific composition ratio has been proposed (see, for example, Patent Document 8). Such an ink also has a similar problem because it contains a specific vinyl ether compound having very high volatility as an essential component. Moreover, the usual vinyl ether compound as described in the above document has a problem of poor polymerizability when it is provided in combination with a pigment.

  In addition, a photosensitive inkjet ink containing a polyvalent vinyl ether compound and an alicyclic epoxy compound is disclosed (for example, see Patent Document 9). The vinyl ether disclosed in this document has the above-described problems of poor polymerizability and carcinogenicity peculiar to the bisphenol A skeleton, and the combination with an alicyclic epoxy having high solubility and dark reactivity. There were problems with storage stability and resistance of printed materials to solvents.

  In particular, when the printing surface is an absorbing medium, the conventional acrylic photocurable inkjet ink has a problem that it is difficult to be cured inside the absorbing paper surface.

The conventional photocation curable ink jet ink has a problem that its viscosity change is severe. This is due to the fact that once an acid is generated due to changes over time, it is difficult to deactivate and there are many dark reactions of ink. In the case of inkjet ink, this problem is extremely serious because if the viscosity changes, the flying shape of the ink will be disturbed, the print reproducibility will be reduced, and in the worst case, it will easily fall into a fatal state such as ejection failure or ink clogging. It was.
JP-A-2-135213 JP 2003-26766 A JP-A-9-110847 JP-A-8-62841 JP 2001-272529 A Japanese Patent Publication No. 2-47510 (EUP-0071345-A2) Japanese Patent Laid-Open No. 9-183928 JP 2001-220526 A U.S. Pat. No. 5,888,084

  An object of the present invention is to provide a cationic curable reactive diluent having high safety while maintaining dilution performance and curing performance.

  In addition, the present invention is highly safe, does not require an organic solvent, and is excellent in ink-jet ink capable of forming a high-quality printed matter without a large exposure system, a colorant dispersion for obtaining such ink, and excellent adhesion. The purpose is to provide printed materials.

  The cationically curable reactive diluent according to one embodiment of the present invention is characterized by containing a vinyl ether compound and limonene dioxide as an acid polymerizable compound that is polymerized in the presence of an acid.

  A color material dispersant according to one embodiment of the present invention includes the above-described cationic curable reactive diluent and a color component.

An ink-jet ink according to an aspect of the present invention is an ink-jet ink containing the above-described color material dispersion, and the cationic curable reactive diluent in the color material dispersion is described below as a part of the acid-polymerizable compound. It contains a vinyl ether compound represented by the general formula (1) and contains 1% by weight or more and 10% by weight or less of a photoacid generator based on the whole acid polymerizable compound.

(In the general formula (1), R ¹ is selected from the group consisting of a vinyl ether group, a group having a vinyl ether skeleton, an alkoxy group, a hydroxyl group-substituted product, and a hydroxyl group, and at least one has a vinyl ether group or a vinyl ether skeleton. ² is a p + 1 valent group having a substituted or unsubstituted cyclic skeleton or aliphatic skeleton, and p is a positive integer including 0.)
The printed matter according to one embodiment of the present invention includes a cured product obtained by curing the above-described inkjet ink.

  According to the aspect of the present invention, a cationically curable reactive diluent having high safety while maintaining dilution performance and curing performance is provided. Further, according to the aspect of the present invention, an inkjet ink that is high in safety, does not require an organic solvent, and can form a high-quality printed matter without a large exposure system, a colorant dispersion for obtaining such an ink, In addition, a printed matter having excellent adhesion is provided.

  Embodiments of the present invention will be described below.

  The cationic curing reactive diluent according to the embodiment of the present invention contains an acid polymerizable compound containing a vinyl ether compound and limonene dioxide. Limonene dioxide has good curability as an epoxy monomer and has excellent adhesion to various media. Moreover, the viscosity at room temperature is as low as about 7 mPa · s, and the compatibility with various resin components is also good. Thus, limonene dioxide has the requirement as a diluent. As a low-viscosity monomer, limonene dioxide has a low level of toxicity for skin irritation and mutagenicity and is at a slightly positive level. Specific examples of limonene dioxide include C3000 (Daicel Chemical Industries), for example.

On the other hand, as the vinyl ether compound, a vinyl ether compound represented by the following general formula (1) is preferably used.

In the general formula (1), R ¹ is selected from the group consisting of a vinyl ether group, a group having a vinyl ether skeleton, an alkoxy group, a hydroxyl group-substituted product, and a hydroxyl group, and at least one has a vinyl ether group or a vinyl ether skeleton. R ² is a p + 1 valent group having a substituted or unsubstituted cyclic skeleton or aliphatic skeleton, and p is a positive integer including 0.

p is 0, when the cyclohexane ring skeleton is introduced as R ^2, from the viewpoint of volatility, it is more preferable that the R ² contains oxygen. Specifically, at least one carbon atom contained in the ring skeleton is preferably a structure having a ketone structure, a structure substituted with an oxygen atom, or a structure having an oxygen-containing substituent.

The number of vinyl ether groups introduced into R ¹ is preferably larger from the viewpoint of curability and is not particularly limited. However, considering solubility as a diluent, it is preferably at most about 2 to 3.

Examples of the (p + 1) -valent organic group R ² include a (p + 1) -valent organic group derived from an aliphatic skeleton and a (p + 1) -valent group including an aromatic ring. Examples of the aliphatic skeleton include alkylene glycol skeletons such as a diethylene glycol skeleton and a triethylene glycol skeleton in addition to an ethane skeleton and a butane skeleton. Moreover, as an aromatic ring, a benzene ring, a naphthalene ring, a biphenyl ring etc. are mentioned, for example. At least one hydrogen atom of the aliphatic skeleton or aromatic ring as described above is substituted with a substituent such as an ether or ester such as a methoxy group, a methoxyethoxy group, an alkoxy group, an acetoxy group or an alkyl ester group. Also good.

Alternatively, a (p + 1) -valent group derived from an alicyclic skeleton can be introduced as R ² . Examples of the alicyclic skeleton include a cycloalkane skeleton, a norbornane skeleton, an adamantane skeleton, a tricyclodencan skeleton, a tetracyclododecane skeleton, a terpenoid skeleton, and a cholesterol skeleton. When the alicyclic skeleton has a crosslinked structure, the hardness of the cured product is increased, which is more desirable. Furthermore, it is more desirable that the alicyclic skeleton contains oxygen from the viewpoint of volatility. Specifically, a structure in which a part of carbon in the cyclic skeleton has a ketone structure, a structure in which an oxygen atom is substituted, a structure having an oxygen-containing substituent, or the like.

  The viscosity of the compound represented by the general formula (1) is usually about 1 mPa · sec to 30 mPa · sec. Therefore, by using these vinyl ether compounds, it is possible to ensure the low viscosity and solubility required for the cationically curable reactive diluent. Furthermore, many of these vinyl ether compounds are extremely safe and negative in toxicity related to skin irritation and mutagenicity.

  Therefore, by combining the vinyl ether compound represented by the general formula (1) and limonene dioxide, a highly safe cationic curable reactive diluent can be obtained without impairing the dilutability. The mixing ratio of the vinyl ether compound and limonene dioxide is preferably in the range of 20:80 to 50:50 by weight. If it is in this range, safety | security and dilution property can be improved further.

Specific examples of the compound represented by the general formula (1) in which a (p + 1) -valent group having an aliphatic skeleton is introduced into R ² are shown below. For example, triethylene glycol divinyl ether (Rapi-CureDVE3: ISP), diethylene glycol divinyl ether (Rapi-CureDVE2: ISP), dodecyl vinyl ether (Rapi-CureDDVE: ISP), 4-hydroxybutyl vinyl ether (Rapi-CureHBVE: ISP) ), Butanediol-1,4-divinyl ether (Rapi-CureDVB1D: ISP), tripropylene glycol divinyl ether (Rapi-CureDPE3: ISP), dipropylene glycol divinyl ether (Rapi-CureDPE2: ISP), hexane Diol divinyl ether (Rapi-CureHDDVE: ISP), 2-hydroxyethyl vinyl ether (HEVE: manufactured by Maruzen Petrochemical), O Fine diethylene glycol mono vinyl ether (DEGV: manufactured by Maruzen Petrochemical Co.), and the like.

Specific examples of those in which R ² is a (p + 1) -valent group having a substituted or unsubstituted cyclic skeleton are shown below. Specific examples of the vinyl ether compound include compounds in which the hydroxyl group in the following alcohol compound is substituted with vinyl ether or propenyl ether. Examples of the alcohol compound include cumene alcohol, vinyloxybenzene, hydroquinone, 1-carbomethoxy-4-vinyloxybenzene, 2-hydroxynaphthalene, 1-tertbutyl-4-vinyloxybenzene, bisphenol A, 1-octyl- Examples include 4-vinyloxybenzene, 1-hydroxy-3,5 dimethylbenzene, 4-hydroxycumylphenol, and 3-isopropylphenol.

Specific examples of the vinyl ether compound are shown in the following chemical formulas Aro1 to Aro11.

  When the cyclic compound is an alicyclic skeleton, it is more preferable than aromatic vinyl ether from the viewpoint of odor and safety. As the vinyl ether compound having such an alicyclic skeleton, a monocyclic ring having a 4- to 6-membered ring skeleton, or an alicyclic skeleton having a bridge structure formed by bonding them is desirable. For example, the compound etc. which substituted the hydroxyl group in the following alicyclic alcohol compounds with vinyl ether or propenyl ether are mentioned. Examples of the alicyclic alcohol include cyclopentane mono (di) ol, cyclopentane mono (di) methanol, cyclohexane (di) ol, cyclohexane mono (di) methanol, norbornane mono (di) ol, and norbornane monool monomethanol. Norbornane mono (di) methanol, tricyclodecane mono (di) ol, tricyclodecane mono (di) methanol, adamantane mono (di) ol, and the like can be used.

More specifically, such an alicyclic skeleton is represented by the following general formula (VE1-a) or (VE1-b).

(In the above general formula, X1 and Z1 are alkylene groups having 1 to 5 atoms, Y1 is an alkylene group having 1 to 2 atoms, and k is 0 or 1.)
Specific examples of the vinyl ether compound having an alicyclic skeleton as described above include compounds in which the hydroxyl group in the following alcohol compound is substituted with vinyl ether or propenyl ether. Examples of the alcohol compound include 4-cyclohexanediol, dicyclopentadienemethanol, isoborneol, 1-tertbutyl-4-vinyloxycyclohexanol, trimethylcyclohexanol, dihydroxyoctahydrophenyl, hydroxytricyclodecane monoene, menthol, 1 , 3 dihydroxycyclohexane, decahydro-2-naphthalenol, vinyloxycyclododecanol, norbornanediol and the like.

More specific examples of vinyl ether compounds are shown in the following chemical formulas Ali1 to Ali14.

  Among these compounds, when the alicyclic skeleton has a bridged structure, the hardness of the obtained cured product is more preferable. Further, RAPI-CURE CHVE: cyclohexane dimethanol divinyl ether, RAPI-CURE CHMVE: cyclohexane dimethanol monovinyl ether, and the like manufactured by ISP Japan are also included.

  When the compound having an alicyclic skeleton has an oxygen-containing structure, it is desirable in terms of volatility and pigment dispersibility. Examples of such a structure include a structure in which a part of carbons in the ring is substituted with an oxygen atom, or an oxygen-containing substituent.

  Examples of the vinyl ether compound having a ring structure having an oxygen-containing substituent include the following compounds. For example, it is a compound in which a hydroxyl group is substituted with a specific substituent in an alcohol compound having a monocyclic ring composed of 4 to 6 members or an alicyclic skeleton having a bridge structure in which they are bonded. For example, at least one hydroxyl group is substituted with an ether or ester such as methoxy group, methoxyethoxy group, alkoxy group, acetoxy group or alkyl ester group, and the remaining hydroxyl group is a compound substituted with vinyl ether or propenyl ether. Can be mentioned. Specifically, the alcohol compound includes cyclopentanediol, cyclohexanedi (tri) ol, cyclohexanedi (tri) methanol, norbornanedi (tri) ol, norbornanemono (di) olmono (di) methanol, norbornanedi ( Examples include tri) methanol, tricyclodecanedi (tri) ol, tricyclodecanedi (tri) methanol, and adamantanedi (tri) ol.

More specifically, a vinyl ether compound having an oxygen-containing substituent represented by the following chemical formula is most desirable.

On the other hand, when an oxygen atom is contained in the alicyclic skeleton, the viscosity stability is further improved, which is more desirable. Examples of such a compound include compounds represented by the following general formula (VE2-a) or (VE2-b).

(In the above general formula, any one of X 2, Y 2 and Z 2 contains at least one oxygen atom, and X 2 and Z 2 are an alkylene group having 1 to 5 atoms or a divalent organic group containing an oxygen atom as an ether bond. Y2 represents an oxygen atom, an alkylene group having 1 to 2 atoms or a divalent organic group containing an oxygen atom as an ether bond, and k is 0 or 1.)
Such a compound exhibits safety of the alicyclic skeleton and excellent curing performance, and a cyclic hydrocarbon skeleton having an oxygen atom as a ring constituent atom exhibits high surface tension. For this reason, it has high solubility and dispersibility.

  As the vinyl ether compound having an alicyclic skeleton having such a structure, a compound having a cyclic ether skeleton having a 4- to 6-membered cyclic skeleton is desirable. For example, the compound etc. which substituted the hydroxyl group in the following alcohol compounds with vinyl ether or propenyl ether are mentioned. Specifically, substituted or unsubstituted oxetane monool, substituted or unsubstituted oxetane monomethanol, oxapentane mono (di) ol, oxacyclohexane mono (di) ol, isosorbitol, mannitol, oxanorbornane mono (di) ) Ol, oxanorbornane monool monomethanol, oxanorbornane mono (di) methanol, oxatricyclodecane mono (di) ol, oxaadamantane mono (di) ol, and dioxolanmentanol.

  Among these compounds, in the structure of the cyclic skeleton portion represented by the general formula (VE2-a) or (VE2-b), the ratio of the number of oxygen atoms to the number of carbon atoms (number of oxygen atoms / number of carbon atoms) is: It is preferable to exceed 0.08. When such a vinyl ether compound is used, an ink exhibiting characteristics with physical properties related to polarity such as solubility and wettability with a printing medium can be obtained. (Number of oxygen atoms / number of carbon atoms) is preferably 0.15 or more, and more preferably 0.25 or more.

Specific examples of vinyl ether compounds include CasNo. 22214-12-6 and CasNo. 20191-85-9. Like these compounds, compounds having a distorted cyclic ether structure such as an oxetane ring and a hydrofuran ring are desirable because the reactivity is also improved. Of these, the hydrofuran ring is desirable from the viewpoint of volatility. Such a cyclic structure is more desirable when it has a bridged structure because the hardness of the cured product is further increased. More specifically, vinyl ethers shown below are most desirable.

  The series of vinyl ether compounds described above are disclosed in, for example, J. Org. Chem. Soc. 1965 (2) 1560-1561 and J.A. Am. Chem. Soc. Vol. 124, no. 8, 1590-1591 (2002) and the like. When such a method is used, the corresponding aromatic alcohol or alicyclic alcohol compound is used as a starting material, and an acetate of vinyl ether or propenyl ether is allowed to act under a catalyst such as iridium halide. As a result, the intended vinyl ether or propenyl ether compound can be easily obtained. For example, menthol vinyl ether (MTVE) can be obtained by heating and stirring menthol and vinyl acetate in a toluene mixed solution of sodium carbonate using an iridium compound as a catalyst under an argon atmosphere.

  Such a synthesis method can be suitably used in the synthesis of any compound exemplified in the present specification.

  As described above, the acid polymerizable compound contained in the cationic curing reactive diluent according to the embodiment of the present invention includes a vinyl ether compound and limonene dioxide as essential components. In addition to these, a third acid-polymerizable compound may be further contained within a range that does not impair the performance as a diluent. By blending the third acid polymerizable compound, curability can be further enhanced. In addition, properties such as adhesion and flexibility of the cured product can be further enhanced. The amount of the third acid polymerizable compound added is desirably 20% by weight or less of the total amount of the acid polymerizable compound. If it is added in excess of 20% by weight, the original performance as a reactive diluent may be impaired. In addition, when a compound positive for skin irritation and mutagenicity is used, safety may be reduced.

  The third acid-polymerizable compound is generally known as an acid-polymerizable compound, and includes a relatively safe compound. For example, a compound having a cyclic ether group such as an epoxy group, an oxetane group, and an oxolane group, an acrylic or vinyl compound having the above-described substituent in the side chain, a carbonate compound, a low molecular weight melamine compound, vinyl carbazoles, Among the monomers with cationically polymerizable vinyl bonds, such as styrene derivatives, alpha-methylstyrene derivatives, vinyl alcohol esters such as vinyl alcohol and acrylic, methacrylic ester compounds, etc. A positive or negative one, a skin irritation PII = 2 or less, and the like are preferable.

  Examples of the epoxy compound having a vinyl group include C2000 (manufactured by Daicel Chemical Industries, Ltd.), and examples of the α-olefin epoxide include AOEX24 (manufactured by Daicel Chemical Industries, Ltd.). Moreover, as an epoxidized vegetable oil, ELSO (made by Daicel Chemical Industries Ltd.) is mentioned, for example. These compounds are particularly suitable as the third acid-polymerizable compound in view of curability and safety.

  The cationic curing reactive diluent according to the embodiment of the present invention may contain a polymerization inhibitor (basic compound). Cationic curable reactive diluents generally tend to have a high viscosity increase over time and cannot be said to have sufficiently high storage stability. By further blending at least one of a basic compound and a compound expressing basicity as a polymerization inhibitor, an increase in viscosity can be suppressed. As a result, the performance can be maintained for a long time.

  As the basic compound, any inorganic base and organic base that can be dissolved in a compound that is polymerized with an acid as described above can be used, and an organic base is desirable from the viewpoint of solubility. Examples of the organic base include ammonia and ammonium compounds, substituted or unsubstituted alkylamines, substituted or unsubstituted aromatic amines, and organic amines having a heterocyclic skeleton such as pyridine, pyrimidine, and imidazole. More specifically, n-hexylamine, dodecylamine, aniline, dimethylaniline, diphenylamine, triphenylamine, diazabicyclooctane, diazabicycloundecane, 3-phenylpyridine, 4-phenylpyridine, lutidine, 2,6 -Di-t-butylpyridine, 4-methylbenzenesulfonyl hydrazide, 4,4'-oxybis (benzenesulfonyl hydrazide), and sulfonyl hydrazides such as 1,3-benzenedisulfonyl hydrazide.

As the basic compound, an ammonium compound can also be used. A preferred ammonium compound is a quaternary ammonium salt represented by the following general formula (3).

(In the above general formula (3), Ra, Rb, Rc and Rd may be the same or different and each is an alkyl, cycloalkyl, alkylaryl or aryl group. (The above aliphatic CH ₂ group may be replaced by an oxygen atom, and X 3 is a basic anion.)
In the compound represented by the general formula (3), Ra to Rd are each methyl, ethyl, propyl, isopropyl, butyl, dodecyl, phenyl, benzyl, X3- is a hydroxide ion, -OR is C1- Anions represented by C4 alkyl base, -OCOR '(R' is alkyl, aryl, alkylaryl), OCOO-, OSOO- are preferably used. Particularly preferred are tetramethylammonium hydroxide and tetrabutylammonium hydroxide. These basic compounds can be used alone or in combination of two or more.

  Although depending on the type of compound used, generally, the effect of a polymerization inhibitor can be obtained if it is blended at a ratio of several hundreds to several thousand ppm with respect to the acid polymerizable compound.

  A color component is contained in the cationic curable reactive diluent as described above to obtain the color material dispersion according to the embodiment of the present invention. The colorant dispersion according to the embodiment of the present invention can be applied not only to a diluent / colorant for an epoxy resin, but also to various paints and printing inks. An ink-jet ink according to an embodiment of the present invention is obtained by blending a photoacid generator into the color material dispersion.

  Examples of the color component contained in the color material dispersion include pigments and / or dyes. However, in the ink-jet ink according to the embodiment of the present invention, as described above, a photoacid generator is mixed and an acid is used for the polymerization mechanism. For this reason, when preparing an ink-jet ink, it is desired to prepare a colorant dispersion using a pigment rather than a dye that easily fades with acid.

  The pigment that can be used as the color component is not particularly limited as long as it has an optical coloring and coloring function required for the pigment, and any pigment can be used. The pigment used here may further exhibit other properties such as magnetism, fluorescence, conductivity, or dielectricity in addition to color development / coloring properties. In this case, various functions can be given to the image. Moreover, you may add the powder which can improve heat resistance and physical strength.

  Examples of usable pigments include light-absorbing pigments. Examples of such pigments include carbon pigments such as carbon black, carbon refined, and carbon nanotubes, metal oxide pigments such as iron black, cobalt blue, zinc oxide, titanium oxide, chromium oxide, and iron oxide, From sulfide pigments such as zinc sulfide, phthalocyanine pigments, pigments composed of salts of metals such as sulfates, carbonates, silicates and phosphates, and metal powders such as aluminum powders, bronze powders, and zinc powders The pigment which becomes is mentioned.

  Further, for example, dye chelates, nitro pigments, aniline black, nitroso pigments such as naphthol green B, azo pigments such as Bordeaux 10B, Lake Red 4R, and chromoftal red (azo lakes, insoluble azo pigments, condensed azo pigments, chelate azos) ), Rake pigments such as peacock blue lake and rhodamine lake, phthalocyanine pigments such as phthalocyanine blue, polycyclic pigments (perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, Organic pigments such as isoindolinone pigments, quinofuranone pigments), selenium pigments such as thioindigo red and indatron blue, quinacridone pigments, quinacridine pigments, and isoindolinone pigments. It is also possible to.

  Examples of pigments that can be used in black ink include Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, manufactured by Colombia, Regal 400R, Regal 330R, Regal 660R, Mogul L, manufactured by Cabot. Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, No. 1 manufactured by Mitsubishi Chemical Corporation. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, No2200B, Degussa Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S150, Color Black S150, Color Black FW200, Color Black FW200, Color Black FW200, Color Black FW200 Carbon blacks such as U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, and Special Black 4 may be mentioned.

  Examples of pigments that can be used in yellow ink include Yellow 128, C.I. I. Pigment Yellow 129, C.I. I. Pigment Yellow 139, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 150, C.I. I. Pigment Yellow 154, C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14C, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 73, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 75, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 98, C.I. I. Pigment Yellow 114, Pigment Yellow 180, and the like. Among these yellow pigments, Pigment Yellow 180, which causes little color deterioration with respect to acid, is preferably used.

  Examples of pigments that can be used in magenta ink include C.I. I. Pigment Red 123, C.I. I. Pigment Red 168, C.I. I. Pigment Red 184, C.I. I. Pigment Red 202, C.I. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 57: 1, C.I. I. Pigment Violet 19 and C.I. I. Pigment Red 112 and the like.

  Further, examples of pigments that can be used in cyan ink include C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15:34, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 60, C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Vat Blue 4, and C.I. I. Vat Blue 60 etc. are mentioned.

  White pigments such as natural clay, lead white, zinc oxide and metal carbonates such as magnesium carbonate, and metal oxides such as barium and titanium are also useful as color components. Ink-jet inks containing a white pigment can be used not only for white printing but also for printing correction and overlaid correction by overwriting.

As the pigment exhibiting fluorescence, either an inorganic phosphor or an organic phosphor may be used. Examples of the inorganic phosphor material include MgWO ₄ , CaWO ₄ , (Ca, Zn) (PO ₄ ) ₂ : Ti ⁺ , Ba ₂ P ₂ O ₇ : Ti, BaSi ₂ O ₅ : Pb ²⁺ , Sr _2. Examples include inorganic acid salts such as P ₂ O ₇ : Sn ²⁺ , SrFB ₂ O _3.5 : Eu ²⁺ , MgAl ₁₆ O ₂₇ : Eu ²⁺ , tungstate and sulfurate.

  Moreover, the following are mentioned as a material of organic fluorescent substance. For example, cyanines such as acridine orange, aminoacridine, quinacrine, anilinonaphthalene sulfonic acid derivatives, anthroyloxystearic acid, auramine O, chlorotetracycline, merocyanine, 1,1′-dihexyl-2,2′-oxacarbocyanine Pigments, dansylsulfoamide, dansylcholine, dansylgalacside, dansyl tolidine, dansyl chloride derivatives such as dansyl chloride, diphenylhexatriene, eosin, ε-adenosine, ethidium bromide, fluorescein, fomycin, 4-benzoylamide-4 '-Aminostilbene-2,2'-sulfonic acid, β-naphthyl triphosphate, oxonol dye, parinaric acid derivative, perylene, N-phenylnaphthylamine, pyrene, safranine O, fluorescamine, fluorescein isocyanate, 7-chloronitrobenzo-2-oxa-1,3-diazole, dansylaziridine, 5- (iodoacetamidoethyl) aminonaphthalene-1-sulfonic acid, 5-iodoacetamidofluorescein, N -(1-anilinonaphthyl 4) maleimide, N- (7-dimethyl-4-methylcumanyl) maleimide, N- (3-pyrene) maleimide, eosin-5-iodoacetamide, fluorescein mercury acetate, 2- (4'- (2 ″ -iodoacetamide)) aminonaphthalene-6-sulfonic acid, eosin, rhodamine derivative, organic EL dye, organic EL polymer, crystal, dendrimer and the like.

  Examples of the powder that can improve the heat resistance and physical strength of the ink layer include aluminum, silicon oxide or nitride, filler, silicon carbide, and the like. In order to impart conductivity to the ink layer, powders such as conductive carbon pigment, carbon fiber, copper, silver, antimony, and noble metals may be added. Iron oxide and ferromagnetic powder are suitable for imparting magnetism, and metal oxide powder such as tantalum and titanium having a high dielectric constant can also be blended.

  In the ink-jet ink according to the present embodiment, it is possible to add a dye as an auxiliary component of the pigment. For example, dyes with low acidity and basicity and high solubility in solvents, such as azoic dyes, sulfur (building materials) dyes, disperse dyes, fluorescent brighteners, and oil-soluble dyes, are usually used. Oil-soluble dyes such as azo, triarylmethane, anthraquinone and azine are preferably used. For example, C.I. I. Slovent Yellow-2, 6, 14, 15, 16, 19, 21, 33, 56, 61, 80, etc., Diresin Yellow-A, F, GRN, GG, etc., C.I. I. Solvent Violet-8, 13, 14, 21, 27, etc., C.I. I. Disperse Violet-1, Sumiplast Violet RR, C.I. I. Solvent Blue-2, 11, 12, 25, 35, etc., Diresin Blue-J, A, K, N etc., Orient Oil Blue-IIN, # 603 etc., Sumiplast Blue BG, etc. can be mentioned.

  The pigments and dyes described above may be used alone or as a mixture of two or more. In addition, pigments and dyes can be used in combination in order to enhance light absorbency, saturation, color feeling, and the like. Furthermore, in order to improve the dispersibility of the pigment, bonding with a polymer binder or microencapsulation treatment may be performed.

  The content of the color component is desirably blended in an amount of 1 to 25% by weight. If it is less than 1% by weight, it is difficult to ensure a sufficient color density. On the other hand, if it exceeds 25% by weight, the ink ejection performance is lowered. The content of the color component is more preferably in the range of 2% by weight to 8% by weight.

  Further, the content of the powder component is preferably 1 to 50% by weight. When the content of the powder component is less than 1% by weight, effects such as an increase in sensitivity are insufficient, and when it exceeds 50% by weight, resolution and sensitivity may be lowered.

  In an inkjet ink, it is desirable that the average particle size of color components and powders be as small as possible. In general, the particle size of the color component and the powder is usually 1/3 or less, more preferably about 1/10 or less of the opening diameter of the nozzle that discharges the inkjet ink. This size is typically 10 μm or less, preferably 1 μm or less. In consideration of sedimentation due to poor dispersion, the particle size suitable as a printing inkjet ink is 0.35 μm or less, and usually has an average particle size of 0.1 to 0.3 μm.

  The ink-jet ink according to the embodiment of the present invention contains a photoacid generator that generates an acid by light irradiation. Examples of the photoacid generator include onium salts, diazonium salts, quinonediazide compounds, organic halides, aromatic sulfonate compounds, bisulfone compounds, sulfonyl compounds, sulfonate compounds, sulfonium compounds, sulfamide compounds, iodonium compounds, sulfonyldiazomethane compounds, And mixtures thereof can be used.

  Specific examples of these compounds include, for example, triphenylsulfonium triflate, diphenyliodonium triflate, 2,3,4,4-tetrahydroxybenzophenone-4-naphthoquinone diazide sulfonate, 4-N-phenylamino- 2-methoxyphenyldiazonium sulfate, 4-N-phenylamino-2-methoxyphenyldiazonium p-ethylphenyl sulfate, 4-N-phenylamino-2-methoxyphenyldiazonium 2-naphthyl sulfate, 4-N-phenyl Amino-2-methoxyphenyldiazonium phenylsulfate, 2,5-diethoxy-4-N-4'-methoxyphenylcarbonylphenyldiazonium-3-carboxy-4-hydroxyphenylsulfate, 2-methoxy -4-N-phenylphenyldiazonium-3-carboxy-4-hydroxyphenyl sulfate, diphenylsulfonylmethane, diphenylsulfonyldiazomethane, diphenyldisulfone, α-methylbenzoin tosylate, pyrogallol trimesylate, benzoin tosylate, manufactured by Midori Chemical Co., Ltd. MPI-103 (CAS.NO. (87709-41-9)), Midori Kagaku BDS-105 (CAS.NO. (145612-66-4)), Midori Kagaku NDS-103 (CAS.NO. (110098-97-0)), MDS-203 (CAS.NO. (127855-15-5)) manufactured by Midori Chemical Co., Ltd., Pyrogallol tritosylate (CAS.NO. (20032-64-8)) manufactured by Midori Chemical Co., Ltd. Green chemistry DTS-102 (CAS.NO. (75482-18-7)), Midori Chemical DTS-103 (CAS.NO. (71449-78-0)), Midori Chemical MDS-103 (CAS.NO) (127279-74-7)), MDS-105 (CAS.NO. (116808-67-4)) manufactured by Midori Chemical Co., Ltd., MDS-205 (CAS.NO. (81416-37-7) manufactured by Midori Chemical Co., Ltd.) ), BMS-105 (CAS.NO. (149934-68-9)) manufactured by Midori Chemical Co., Ltd. TMS-105 (CAS.NO. (127820-38-6) manufactured by Midori Chemical Co., Ltd.), NB- manufactured by Midori Chemical Co., Ltd. 101 (CAS.NO. (20444-09-1)), Midori Kagaku NB-201 (CAS.NO. (4450-68-4)), Midori Kagaku DNB-10 (CAS. NO. (114719-51-6)), Midori Chemical Co., Ltd. DNB-102 (CAS.NO. (131509-55-2)), Midori Chemical Co., Ltd. DNB-103 (CAS.NO. (132898-35-2)) DNB-104 (CAS.NO. (132898-36-3)), Midori Chemical Co., Ltd., DNB-105 (CAS.NO. (132898-37-4)), Midori Chemical Co., Ltd., DAM-101 (CAS.NO. (1886-74-4)), Midori Kagaku DAM-102 (CAS.NO. (28343-24-0)), Midori Kagaku DAM-103 (CAS.NO. (14159-)) 45-6)), DAM-104 (CAS.NO. (130290-80-1), CAS.NO. (130290-82-3)), Midori Chemical DAM-201 (CAS.NO. (2832-50-1)), CMS-105, Midori Chemical Co., Ltd., DAM-301 (CAS. No. (138529-81-4)), Midori Chemical Co., Ltd. SI-105 (CAS. No. (34694-40-7)), Midori Chemical Co., Ltd. NDI-105 (CAS. No. (133710-62-0)), Midori Chemical Co., Ltd. EPI-105 (CAS. No. (135133-12-9)), and UVACURE1591 manufactured by Daicel UCB.

  The content of such a photoacid generator is usually 1 to 10% by weight of the total amount of the acid polymerizable compound. When the amount is less than 1% by weight, the effect cannot be sufficiently obtained. On the other hand, when the content exceeds 10% by weight, there is a possibility that inconvenience such as deterioration of storage stability may occur. However, when a photosensitizer as described later is used in combination, it can be reduced to about 60% or less with respect to the content of the photoacid generator when no photosensitizer is contained.

A photosensitizer can be blended in the inkjet ink according to the embodiment of the present invention. Examples of the photosensitizer include an anthracene diether compound represented by the following general formula (2).

(In the general formula (2), R ¹⁰ is a monovalent organic group having 1 to 5 carbon atoms, R ¹¹ and R ¹² may be the same or different, a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, An alkylsulfonyl group or an alkoxy group.)
Examples of the monovalent organic group that can be introduced as R ¹⁰ in the general formula (2) include an alkyl group, an aryl group, a benzyl group, a hydroxyalkyl group, an alkoxyalkyl group, and a vinyl group.

  Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, and i-pentyl group. Etc. Examples of the aryl group include a phenyl group, a biphenyl group, an o-tolyl group, an m-tolyl group, and a p-tolyl group. Examples of the hydroxyalkyl group include a 2-hydroxyethyl group and a 3-hydroxypropyl group. Group, 2-methyl-2-hydroxyethyl group, 2-ethyl-2-hydroxyethyl group and the like. Examples of the alkoxyalkyl group include a 2-methoxyethyl group, a 3-methoxypropyl group, a 2-ethoxyethyl group, and a 3-ethoxypropyl group. Furthermore, an allyl group, 2-methylallyl group, benzyl group, vinyl group or the like may be introduced. Such a compound can be synthesized by a method as shown in, for example, (J. Am. Chem. Soc., Vol. 124, No. 8 (2002) 1590).

The R ¹⁰ O group in the general formula (2) is preferably a group that is polymerized by an acid. Examples of such R ¹⁰ O groups include vinyl ether groups, propenyl ether groups, epoxy groups, oxetane groups, and oxolane groups. Such an acid-polymerizable group is incorporated into the polymerization reaction product because the photosensitizer itself participates in the polymerization during the polymerization reaction with an acid. Further, when the R ¹⁰ O group is a group that dissociates with an acid or heat to generate an OH group, it is similarly incorporated into the polymerization reaction product. Examples of such R ¹⁰ O groups include a tert-butyl group, a tert-butoxycarbonyl group, an acetal group, and a silicone-containing group.

That is, when the R ¹⁰ group itself in the general formula (2) is polymerized, this photosensitizer becomes a part of the polymerization product. Alternatively, when an OH group generated by acid or heat in the photosensitizer is bonded to the acid polymerizable compound, the photosensitizer becomes part of the polymerization product. As a result, the degree of polymerization of the polymerization reaction can be further advanced, and the final curing performance (hardness) can be improved. Therefore, by using the inkjet ink according to the embodiment of the present invention, the polymerization reaction can be obtained. The durability of the printed material obtained can also be improved.

In the general formula (2), R ¹¹ and R ¹² represent a hydrogen atom, a C1-C3 alkyl group, an alkylsulfonyl group or an alkoxy group. Any group may be used as long as these groups are used, but there is no problem even if R ¹¹ and R ¹² are both hydrogen atoms in view of the ease of synthesis.

  Examples of the compound represented by the general formula (2) include 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, and 2-ethyl-9. Dialkoxyanthracene such as 1,10-diethoxyanthracene (2,3-diethyl-9,10-diethoxyanthracene), 9,10-diphenoxyanthracene, 9,10-diallyloxyanthracene, 9,10- Examples include di (2-methylallyloxy) anthracene, 9,10-divinyloxyanthracene, 9,10-di (2-hydroxyethoxy) anthracene, and 9,10-di (2-methoxyethoxy) anthracene. Any of these compounds exerts a sufficient effect, but in consideration of the cost of obtaining the compound or its synthesis raw material and the safety of the compound, 9,10-dibutoxyanthracene and 9,10-divinyl Oxyanthracene is particularly preferred.

  Depending on the type of compound used, in general, if the photosensitizer is blended at a ratio of about 10 to 50% with respect to the weight of the photoacid generator, it will exert its effect. Can do.

A thickener for adjusting to an optimum viscosity value as an inkjet ink may be added to the inkjet ink according to the embodiment of the present invention.
Any thickener can be used as long as it is soluble in the ink-jet ink solvent of the present invention and does not affect performance such as ejection performance and storage stability. Examples thereof include resin components (including oligomers) and metal soaps.

  More specifically, natural resins such as rosin, gilsonite, zein and derivatives thereof, and synthetic resins include phenol resins, rosin-modified phenol resins, xylene resins, urea resins, melamine resins, petroleum resins, terpene resins, alkyd resins, Examples thereof include polyamide resins, acrylic resins, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer resins, polyvinyl acetate, polyvinyl butyral, epoxy resins, polyurethane, and cellulose derivatives.

  Oil thickeners such as hydrogenated castor oil, metal soaps such as aluminum stearate and aluminum octoate, aluminum chelates, organic bentonite, polyethylene oxide, long-chain polyaminoamides, polycarboxylic acid alkylamines, etc. are also used as thickeners. Can be used.

  The weight average molecular weight of these resin components is preferably 100,000 or less. When the weight average molecular weight exceeds 100,000, there is a possibility that the discharge performance of the inkjet ink is deteriorated. The lower limit of the weight average molecular weight is not particularly limited, but is usually about 1000. The weight average molecular weight of the resin component can be measured by a technique such as GPC (Gel Permeation Chromatography).

  The inkjet ink according to the embodiment of the present invention is applied to, for example, an inkjet recording apparatus used for printing. In such a recording apparatus, the print heads are usually arranged in a line for speeding up, and printing is performed in one pass on the print surface. Therefore, an ejection error results in a linear print defect (missing) on the printing surface. It is indispensable to eliminate such errors as much as possible, and the ink used is required to have very high printing accuracy and ejection stability.

  The inkjet ink according to the embodiment of the present invention is a cationic polymerization type and has high reactivity. For this reason, the change in physical properties such as the viscosity is essentially large and unstable. This is due to the fact that once an active species is generated for some reason (for example, heat), it is not easily deactivated, and there are many dark reactions of ink.

  Furthermore, recent research has shown that in order to increase the stability of these inks, it is necessary to stabilize the ink state not only in the macro but also in the micro. For example, in general, the smaller the particle diameter and the higher the dispersion stability of an ink, the fewer printing errors. Inks containing ionic substances (such as polymerization initiators and surfactants) including inks such as cationic polymerization types generally tend to cause aggregation over time due to an action similar to salting out in a colloidal dispersion system. For this reason, there existed a problem that it was inferior to storage stability. If the components react to change viscosity, surface tension, elastic force, etc., the flying shape of the ink will be disturbed, the print reproducibility will be reduced, and in the worst case, it will easily fall into a fatal state such as ejection failure or ink clogging. The problem was extremely serious.

  That is, if a component having a large weight average molecular weight is contained, it may cause gelation of the acid polymerizable compound. In addition, the coarse particles generated from the aggregation of the resin component itself and the color material may be a factor that hinders the discharge performance. Therefore, it is desirable to use a resin component having a low molecular weight as much as possible within a range in which the viscosity of the ink can be adjusted. In order to avoid a decrease in discharge performance as much as possible, the weight average molecular weight is more preferably 100,000 or less.

  The addition amount of the thickener can be appropriately determined according to the weight average molecular weight of the resin component used. For example, in the case of a thickener having a molecular weight of about 20,000, the effect can be obtained if it is blended at a ratio of about 1 to 3% by weight with respect to the acid polymerizable compound.

  The inkjet ink according to the embodiment of the present invention may further contain a small amount of a dispersant such as a nonionic or ionic surfactant or a charging agent in order to enhance dispersibility of pigments and the like. Polymeric dispersants such as acrylic and vinyl alcohol having similar properties are also preferably used. However, when a cationic dispersant is used as the dispersant, it is desirable to select a compound having a lower acidity than the carboxylic acid. This is because some cationic dispersants promote the curing dark reaction of the ink. In addition, a dispersant or a pigment having a strong basicity may not only lower the sensitivity of the ink but also accelerate the curing dark reaction. Therefore, as such a dispersant, it is desirable to use a neutral or nonionic compound.

  Specifically, as the polymer dispersant, for example, Solsperse 24000, Solsperse 32000 (both manufactured by Avicia) and the like can be used. If such a polymer dispersant is blended at a ratio of about 5 to 30% of the weight of the pigment, the effect can be exhibited.

  Next, a printing method using the inkjet ink of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram schematically showing a typical recording apparatus for performing recording using the ink jet ink as described above. The illustrated inkjet recording apparatus 1 includes a transport mechanism 3 that transports a recording medium 2. From the upstream side to the downstream side along the moving direction of the transport mechanism 3,
An ink jet recording head 4, a light source 5, and a heater as a heating mechanism 6 are sequentially arranged.

  The recording medium (or printed material) 2 is not particularly limited as long as it is a printable medium. As the recording medium 2, for example, paper, an OHP sheet, a resin film, a nonwoven fabric, a porous film, a plastic plate, a circuit board, a metal substrate, and the like can be used.

  For example, the transport mechanism 3 transports the medium 2 so that the recording medium 2 sequentially passes through the front surface of the recording head 4, the light source 5, and the heater 6. Here, the transport mechanism 3 transports the recording medium 2 from the right side to the left side in the drawing. The transport mechanism 3 can be configured by, for example, a belt and / or roller that moves the recording medium 2 and a drive mechanism that drives the belt and / or roller. The transport mechanism 3 may further be provided with a guide member that assists in moving the recording medium 2.

  The recording head 4 discharges inkjet ink onto the recording medium 2 in response to the image signal to form an ink layer. As the recording head 4, for example, a serial scanning type head mounted on a carriage or a line scanning type head having a width equal to or larger than the width of the recording medium 2 can be used. From the viewpoint of high-speed printing, the latter is usually more advantageous than the former. There is no particular limitation on the method of ejecting ink jet ink from the recording head 4. For example, ink droplets can be ejected using the pressure of vapor generated by the heat of the heating element. Alternatively, ink droplets may be ejected using a mechanical pressure pulse generated by a piezoelectric element.

  The light source 5 irradiates the ink layer on the recording medium 2 with light to generate an acid in the ink layer. Examples of the light source 5 include a mercury lamp such as a low, medium, and high pressure mercury lamp, a tungsten lamp, an arc lamp, an excimer lamp, an excimer laser, a semiconductor laser, a YAG laser, a laser system that combines a laser and a nonlinear optical crystal, A high frequency induced ultraviolet ray generator, an electron beam irradiation device, an X-ray irradiation device, or the like can be used. Among these, since the system can be simplified, it is desirable to use a high frequency induced ultraviolet ray generator, a high / low pressure mercury lamp, a semiconductor laser, or the like. The light source 5 may be provided with a condensing mirror and a running optical system as necessary.

  The heater as the heating mechanism 6 heats the ink layer on the recording medium 2 and promotes a crosslinking reaction using an acid as a catalyst. Specifically, as the heater, for example, an infrared lamp, a roller (heat roller) with a built-in heating element, warm air or a blower that blows hot air can be used.

Using such an apparatus 1, printing can be performed on a recording medium by the following method, for example.
First, the recording medium 2 is transported from the right side to the left side in the drawing by the transport mechanism 3. The conveyance speed of the recording medium 2 can be set within a range of 0.1 m / min to several hundreds m / min, for example.

  When the recording medium 2 is conveyed to the front of the recording head 4, the recording head 4 ejects the above-described inkjet ink corresponding to the image signal. Thereby, a predetermined ink layer (not shown) is formed on the recording medium 2.

The recording medium 2 having an ink layer is conveyed to the front of the light source 5. When the recording medium 2 passes in front of the light source 5, the light source 5 emits light toward the ink layer formed on the recording medium 2 to generate an acid in the ink layer. The irradiation light intensity at the position of the ink layer surface varies depending on the wavelength of the light source used, but can usually be in the range of several mW / cm ^{2 to 1} kW / cm ² . The exposure amount to the ink layer can be appropriately set according to the sensitivity of the inkjet ink, the moving speed of the printing surface (conveying speed of the recording medium 2), and the like.

  Subsequently, the recording medium 2 is conveyed into or near the heater 6. When the recording medium 2 passes through or in the vicinity of the heater 6, the heater 6 heats the ink layer formed on the recording medium 2 and promotes a crosslinking reaction in the ink layer. In the apparatus 1 shown in FIG. 1, the heating time by the heater 6 is usually relatively short, from several seconds to several tens of seconds. Accordingly, when the ink layer is cured almost completely by the heater 6, the maximum temperature reaches, for example, about 200 ° C. or less, preferably 60 ° C. to 200 ° C. or preferably about 80 ° C. to 180 ° C. Heat to.

Thereafter, the recording medium 2 is conveyed into a stocker (or container) (not shown). Thus, printing is completed.
The heating mechanism for heating the ink layer is not limited to the heater 6 disposed downstream of the light source as shown in FIG. For example, when the ink layer is exposed, the light source 5 can be used as a heat source by bringing the light source 5 close to the recording medium 2 to the extent that the printing surface is not damaged. By not providing a heat removal mechanism such as a cold mirror in the light source, the light source may be similarly used as a heat source. In the case of a high-power valve of several hundred watts, since it has a cooling mechanism at the same time, it is only necessary to change a part of the exhaust heat mechanism and provide a mechanism for intentionally reducing the heat to the paper surface. . Accordingly, the ink layer can be heated by the heat generated from the light source.

  For example, a light source with an output of 100 w or more having a mechanism used for heating by re-introducing an air stream that has cooled the light source into a paper surface or a transport / holding mechanism. The temperature reached by the recording medium due to the reduction of the heat of the light source may be a temperature at which the same effect as the heating by the heater described above is obtained. The preferred temperature depends on the heating time, but is usually at least 60 ° C. or higher, more preferably 80 ° C. to 100 ° C. In addition, when the exposure speed is as high as several m / second, it may be heated to about 180 ° C. because it is heated instantaneously.

  For example, when a light source 5 that can generate infrared light in addition to visible light is used, heating can be performed simultaneously with light irradiation. In this case, since hardening can be accelerated | stimulated, it is preferable.

  When the ink layer is irradiated with light, the ink layer is heated by the heat generated from the light source 5, so that the heating mechanism is not necessarily provided as an independent member like the heater 6. However, it takes a long time to completely cure the ink layer by allowing it to stand at room temperature only with heat from the light source 5. Therefore, it is desirable that the standing at room temperature is applied to an application that can secure a sufficiently long time until complete curing. For example, a printed matter such as a newspaper announcement distributed the next day can secure a long time of about one day and night until it is cured, so that it can be completely cured even at room temperature.

  An image (printed material) formed by such a recording method and ink has high curing performance as well as print quality, and can be excellent in all of hardness, adhesion, light resistance, and safety. In addition to almost no radiation of harmful substances, printing after curing can be suppressed to within 10% even in weight reduction during exposure. For this reason, the scattered matter in the printing atmosphere is reduced as much as possible, which is desirable. By curing the inkjet ink according to the embodiment of the present invention, a printed matter having excellent characteristics can be obtained.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

Example 1
CHVE and DVE3 were prepared as vinyl ether compounds (VE), and C3000 was prepared as limonene dioxide (LOX). The vinyl ether compound and limonene dioxide were mixed at various blending ratios (weight ratios) to prepare the cationic polymerization type reactive diluent of this example. Specifically, the blending ratio of the vinyl ether compound and limonene dioxide was changed between the weight ratios of 10:90 to 60:40. That is, the content of the vinyl ether compound relative to the total amount of the vinyl ether compound and limonene dioxide was varied between 10 and 60% by weight.

The safety concerning the mutagenicity of the obtained cationic polymerization type reactive diluent was evaluated by a reverse mutation test using bacteria (Ames test). For comparison, the case where limonene dioxide and vinyl ether were used alone was also examined. The results are summarized in Table 1 below, with positive (×), fine positive (Δ), and negative (◯). If it is slightly positive, there is no safety problem.

  Further, the resin was diluted with each cationic polymerization type reactive diluent, and the viscosity of the obtained diluted solution was measured to examine the dilution effect. Specifically, bisphenol A type epoxy resin (Adeka Resin EP-4100, Asahi Denka Kogyo Co., Ltd.) was used as an epoxy resin, and mixed with each diluent at a blending ratio of 50% by weight. That is, the weight ratio between the bisphenol A type epoxy resin and the diluent is 1: 1.

  Using BGE (butyl glycidyl ether) as a diluent, the same epoxy resin was mixed at a blending ratio of 50% by weight to prepare a diluent. With reference to the viscosity of this BGE diluted solution, the ratio (target diluted solution / BGE diluted solution) was determined for each diluted solution and evaluated according to the following criteria.

Less than 1: ◎ (good)
1 to less than 2: ○ (slightly good)
2 or more: △ (somewhat bad)
The results obtained are summarized in Table 2 below. For comparison, the case where limonene dioxide and vinyl ether were used alone was also examined.

  From the results of Table 1 above, it can be seen that when the content of the vinyl ether compound is 20% by weight or more, the safety is further improved. Moreover, it turns out that the dilution effect improves more by making the content of a vinyl ether compound into 50 weight% or less from the result of Table 2. From the above results, the weight ratio (VE: LOX) between the vinyl ether compound and limonene dioxide is preferably in the range of 20:80 to 50:50.

  Moreover, the diluent which mix | blended CHVE and C3000 as a vinyl ether compound with the weight ratio of 30:70 was prepared, and the dilution property with respect to various resin was evaluated similarly to the above. Examples of the resin include bisphenol F type epoxy resin, bisphenol AD type epoxy resin, polyvinyl butyral (BL-1, ESREC), terminal hydroxy polyester (PLACCEL), polyisoprene rubber (KL-613), and xylene resin (HP-70, Nicanol) was used. For any of the resins, it was confirmed that the diluent of this example exhibited good dilution performance.

  Further, a diluent was prepared in the same manner as described above except that the vinyl ether compound was changed to DVE3, and the dilutability with respect to various resins was examined. As a result, similar results were obtained for all the resins.

(Example 2)
CHVE as a vinyl ether compound and C3000 were blended at a weight ratio of 30:70 to prepare a cationic polymerization type reactive diluent. Furthermore, C2000 as a 3rd acid polymeric compound was mixed, and the diluent of the present Example was obtained. The blending amount of the third acid polymerizable compound was 10 to 40% by weight of the total acid polymerizable compound. The viscosity of these diluents was measured in the same manner as in Example 1, and the dilution performance was examined in comparison with the BGE diluent. The results are summarized in Table 3 below. Moreover, the diluent was prepared by the same prescription except having changed the vinyl ether compound into DVE3, and evaluated similarly.

  As shown in Table 3 above, when the content of the third acid polymerizable compound is 20% by weight or less of the total acid polymerizable compound, a good dilution effect is maintained. Therefore, the blending amount of the third acid polymerizable compound is preferably 20% by weight or less of the total acid polymerizable compound.

  Further, a diluted solution was prepared in the same manner as described above except that the third acid polymerizable compound was changed to AOEX24 or ELSO. When the dilution characteristics were evaluated in the same manner as described above, the same results as in the case of C2000 were obtained.

(Example 3)
Using the diluent prepared in Example 1, a light irradiation type cationic curable reactive diluent was prepared. Specifically, triphenylsulfonium triflate as a photoacid generator (PAG) is added in a proportion of 4% by weight with respect to the total amount of the acid-polymerizable compound, and stirred and mixed to produce light irradiation type cationic curing. A mold reactive diluent was prepared. The obtained reactive dilution was applied to a PET film with a bar coater to a thickness of about 5 μm to form a coating film, and UV light was irradiated from a UV irradiation device. Further, it was placed on a hot plate and subjected to a heat treatment at 80 ° C. for 3 minutes to cure the reactive diluent in the coating film to form a cured film.

The obtained cured film was subjected to a cross-cut tape peeling test, and the adhesion was evaluated by the ratio of the area where the cured film was peeled off. The case where the peeled area was less than 5% of the whole was extremely good (A), and the case where the area was less than 10% was good (O). The results are summarized in Table 4 below.

  From the results of Table 4 above, it can be seen that the diluent containing DVE3 as the vinyl ether compound has better adhesion than the diluent containing CHVE. Even when compared with other vinyl ether compounds, it was confirmed that the diluent using DVE3 generally has a good tendency in adhesion. When importance is attached to the curing performance, it can be said that DVE3 is suitable as the vinyl ether compound.

Example 4
Among the diluents prepared in Example 1, a polymerization inhibitor-containing diluent was prepared using a vinyl ether compound content of 30% by weight. Specifically, pyridine as a polymerization inhibitor was added at a ratio of 2% by weight with respect to the photoacid generator, and the mixture was stirred and mixed to prepare a polymerization inhibitor-containing diluent. This diluent was stored at 50 ° C. for 2 weeks, and the viscosity before storage and the viscosity after storage were measured to determine the rate of increase in viscosity. The storage performance was evaluated with an increase rate of less than 3% being good (）) and 3% or more being slightly good (○), and the results are summarized in Table 5 below.

  From the results shown in Table 5 above, it was found that the storage stability of the diluent was improved by adding a polymerization inhibitor. Therefore, by adding a polymerization inhibitor, handling of the diluent, handling, storage and transportation becomes easier.

  Similar results were obtained when the same amounts of dimethylaniline and methoquinone were added as polymerization inhibitors.

(Example 5)
A pigment dispersion was blended as a color component to prepare a colorant dispersion, and its storage performance was examined. The black pigment carbon black was used as the pigment, and the following treatment was performed together with the dispersant.

10% by weight of pigment
Dispersant (Avicia Solsperse 32000) 3% by weight
Dispersant (Abyssia Solsperse 22000) 0.3% by weight
C3000 / DVE3 diluent prepared in Example 1 86.7 wt%
The vinyl ether content in the diluent used is 30% by weight.

  The mixed solution containing these was filled with 0.3 mm diameter beads in a circulating sand mill, and subjected to a dispersion treatment for about 1 hour. For the comparative example, a colorant dispersion was prepared by carrying out a dispersion treatment in the same manner as described above except that C3000 alone and DVE3 alone were used as diluents.

The obtained color material dispersion was subjected to a storage test under the same conditions as in Example 4, and the storage performance was evaluated from the increase rate of the viscosity and the particle diameter of the pigment. Concerning the viscosity, as in Example 4 above, the rate of increase after storage for 2 weeks is less than 3% is good (◎), 3% or more is slightly good (◯), and 10% or more is slightly bad ( Δ). Regarding the particle diameter, an increase rate of 10% or less was good (◎), and if it exceeded 10%, it was judged as slightly bad (◯). The results obtained are summarized in Table 6.

  As shown in Table 6 above, in the dispersion using the diluent of the example containing C3000 and DVE3, an increase in the particle diameter of the pigment is suppressed. Moreover, the rate of increase in viscosity is extremely small. In contrast, an increase in viscosity was observed in the dispersion using DVE3 alone. The colorant dispersion using C3000 alone has relatively good storage stability, but it is desired to use it together with a vinyl ether compound in view of safety. Since it was provided with storage stability and safety, it was confirmed that the dispersion liquid in which the coloring material was dispersed in the diluent of the example was the most excellent.

  Similar results were obtained for the colorant dispersion prepared with the same formulation except that the pigment was changed. Specifically, even when PY-180 is used as the yellow pigment, PR-122 is used as the magenta pigment, and PB-15: 3 is used as the cyan pigment, the dispersion prepared using the diluent of the example has a viscosity of And the increase in particle size was suppressed.

(Example 6)
First, an acid polymerizable compound was blended according to the formulation shown in Table 7 below to prepare diluted solutions of Examples and Comparative Examples.

  BGE and SR-2EG used in the comparative examples are butyl glycidyl ether and ethylene glycol diglycidyl ether, respectively.

  An inkjet ink was prepared by mixing the obtained diluent, a colorant dispersion and a photoacid generator, and the characteristics thereof were examined. As the colorant dispersion, the dispersion prepared in Example 6 was used, and UVACURE1591 was used as the photoacid generator, and an inkjet ink was prepared according to the following formulation.

Diluent 50% by weight
Color material dispersion 50% by weight
Photoacid generator 8% by weight
These components were mixed and stirred for about 6 hours using a homogenizer or the like. Next, the obtained mixture was filtered through a 5 μm membrane filter to obtain an inkjet ink.

Each ink was applied to a PET film with a bar coater to a thickness of about 5 μm to form a coating film, and irradiated with UV light from a UV irradiation device. Further, it was placed on a hot plate and subjected to heat treatment at 80 ° C. for 3 minutes to form a cured film. About the cured film obtained in this way, pencil hardness was measured and the adhesiveness by crosscut was investigated. Further, the storage stability was evaluated by the same method as in Example 5, and the safety was evaluated by the same method as in Example 1. The results obtained are summarized in Table 8 below.

  As shown in Table 8 above, the inks of the examples are superior to the comparative inks in terms of curing hardness and safety. In addition, the inks of the examples all had good ejection performance from the inkjet head and could be ejected without any problem.

  Furthermore, the cured film was formed on the metal medium using the ink of the Example, and adhesiveness was evaluated. When stainless steel, aluminum, and copper were used as the metal medium, it was confirmed that the metal medium had good adhesion performance for any metal.

Further, ink was prepared by changing the amount of the photoacid generator added to the ink (Ink-A2), and the curability and storage stability were evaluated. The results are summarized in Table 9 below.

  As shown in Table 9 above, when the amount of the photoacid generator is less than 1% by weight, the ink is not cured. On the other hand, when it exceeds 10 weight% and it adds excessively, it exists in the tendency for preservability to fall. In addition, when an excessive amount of the photoacid generator is added, it may be a factor for promoting corrosion in the ink jet head. Furthermore, the molecular weight of the polymer of the acid polymerizable compound cannot be sufficiently increased due to the influence of excess acid. Therefore, in order to achieve both the hardness of the cured film and the storage stability of the ink, the content of the photoacid generator is preferably in the range of 1 to 10% by weight of the acid polymerizable compound.

(Example 7)
A photosensitizer was blended with the ink Ink-A2 to prepare an ink (Ink-A2-1). 9,10-dibutoxyanthracene was used as the photosensitizer, and the amount added was 35% by weight with respect to the amount of the photoacid generator. The photosensitizer was previously dissolved in a diluent and then mixed with the colorant dispersion. The ink curability was evaluated and the results are summarized in Table 10.

  Table 10 shows that by blending the photosensitizer, a hardness of 2B can be obtained even when the content of the photoacid generator is 0.5% by weight. Thus, it was confirmed that the curing performance is improved.

(Example 8)
Inks Ink-A1-2 to Ink-A10-2 were prepared by adding a thickener to the inks Ink-A1 to Ink-A10. As a thickener, polyvinyl acetal resin (BL-1) was used, and the amount added was 2% by weight or less based on the acid polymerizable compound. The weight average molecular weight of the resin (BL-1) used here is about 20,000.

  The thickener was added in advance with a predetermined amount to the diluent to reliably dissolve the resin component, and then mixed with the colorant dispersion and the photoacid generator. It is more preferable to use a solution obtained by filtering a mixed solution in which a thickener is dissolved in a diluent with a PTFE filter having a film thickness of 1 μm.

  Images were formed using these inks, and the printed image was visually confirmed to evaluate the ejection performance. As a result, there was no omission when any ink was used, and the ejection performance was extremely good. It was found that by adding (BL-1), the viscosity can be adjusted without deteriorating the discharge performance.

  Further, the ink Ink-A1-3 to Ink-A10-3 was prepared by changing the thickener to polyvinyl acetal resin (BX-3), and the ejection performance was similarly evaluated. The weight average molecular weight of the resin (BX-3) exceeds 100,000.

  An image was formed using the obtained ink, and the printed image was evaluated in the same manner. As a result, several missing points were confirmed. From this result, it is understood that a resin component having a weight average molecular weight of 100,000 or less is preferable as the thickener. In addition, by adding an appropriate amount of other thickeners, it is possible to more easily control the viscosity of the ink in accordance with the ejection conditions of the inkjet head.

Example 9
Inks Ink-A1-4 to Ink-A10-4 were prepared by blending ink dispersants Ink-A1 to Ink-A10 with a polymer dispersant. As a polymer dispersant, Ajisper PB711 (manufactured by Ajinomoto Fine Techno) was used and added at a ratio of 30% of the weight of the pigment. This was mixed and stirred for about 1 day to obtain the desired ink. In preparing the ink, it is more preferable to mix the colorant dispersion after mixing the polymer dispersant and the photoacid generator in the diluent.

  Using these inks, storage stability was evaluated in the same manner as in Example 6. As a result, in any of the inks, the rate of increase in viscosity after storage for 4 weeks was 10% or less, and the rate of increase in particle diameter was 10% or less. Thus, it was shown that by adding the polymer dispersant, it is possible to suppress the increase rate of the viscosity while maintaining the stability of the particle diameter and to further improve the storage stability.

1 is a schematic view of a recording apparatus that can use an inkjet ink according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus; 2 ... Recording medium; 3 ... Conveyance mechanism,
4 ... Inkjet recording head; 5 ... Light source; 6 ... Heater.

Claims (13)

  A cationically curable reactive diluent comprising a vinyl ether compound and limonene dioxide as an acid polymerizable compound that is polymerized in the presence of an acid.   2. The cationically curable reactive diluent according to claim 1, wherein the vinyl ether compound and the limonene dioxide are contained in a weight ratio of 20:80 to 50:50.   3. The cation-curable reactive diluent according to claim 1, wherein the total amount of the vinyl ether compound and the limonene dioxide is 80% by weight or more of the total acid polymerizable compound.   4. The cationically curable reactive diluent according to any one of claims 1 to 3, wherein the vinyl ether compound is triethylene glycol divinyl ether.   The cationic curable reactive diluent according to any one of claims 1 to 4, further comprising a polymerization inhibitor.   A colorant dispersion comprising the cationic curable reactive diluent according to any one of claims 1 to 5 and a color component. An inkjet ink comprising the colorant dispersion according to claim 6,
The cationically curable reactive diluent in the colorant dispersion contains a vinyl ether compound represented by the following general formula (1) as a part of the acid polymerizable compound, and is 1% by weight or more of the total acid polymerizable compound. An ink-jet ink comprising 10% by weight or less of a photoacid generator.

(In the general formula (1), R ¹ is selected from the group consisting of a vinyl ether group, a group having a vinyl ether skeleton, an alkoxy group, a hydroxyl group-substituted product, and a hydroxyl group, and at least one has a vinyl ether group or a vinyl ether skeleton. ² is a p + 1 valent group having a substituted or unsubstituted cyclic skeleton or aliphatic skeleton, and p is a positive integer including 0.)   The inkjet according to claim 7, further comprising at least one selected from the group consisting of vinylcyclohexene monooxide 1,2-epoxy-4-vinylcyclohexane, α-olefin epoxide, and epoxidized vegetable oil. ink. The inkjet ink according to claim 7 or 8, further comprising a photosensitizer represented by the following general formula (2).

(In the general formula (2), R ¹⁰ is a monovalent organic group having 1 to 5 carbon atoms, R ¹¹ and R ¹² may be the same or different, a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, An alkylsulfonyl group or an alkoxy group.)   The inkjet ink according to claim 7, further comprising a thickener.   The inkjet ink according to claim 10, wherein the thickener is a resin component having a weight average molecular weight of 100,000 or less.   The inkjet ink according to claim 7, further comprising a polymer dispersant.   A printed matter comprising a cured product obtained by curing the inkjet ink according to any one of claims 7 to 12.

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