JP2005325155A - Actinic-radiation-curing composition, actinic-radiation-curing ink, actinic-radiation-curing inkjet recording ink, and image formation method and print using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actinic-radiation-curing inkjet recording ink which can give a cured film having high strength, excellent adhesion to substrate, and crack-freeness and can therefore give a good image. <P>SOLUTION: The actinic-radiation-curing composition is an actinic-radiation-curing composition comprising a cationically polymerizable compound and a photo acid generator, wherein the cured film just after being cured by irradiation with an actinic radiation has a logarithmic decrement peak temperature of 120 to 180°C as measured with a pendulum viscoelastometer. The actinic-radiation-curing inkjet recording ink using the same is also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an actinic ray curable composition, and more particularly to an image forming method and printed matter using the composition as an ink for ink jet recording.

  The actinic radiation curable ink using the actinic radiation curable composition has advantages such as excellent quick-drying, no need for a drying process by heat, and no environmental pollution because it is solvent-free. It is becoming used. Such actinic ray curable compositions can be used not only for printing inks, but also for coating materials such as cans, plastics, paper, and wood, adhesives, and optical three-dimensional molded article preparation materials.

  There are a radical polymerization type and a cation polymerization type as the actinic ray curable composition, but the cation polymerization type is not affected by oxygen polymerization inhibition, and ionic polymerizable monomers such as oxetane and epoxy have a small odor, It has attracted attention because of its advantages such as low cure shrinkage.

As the polymerizable monomer used in the cationic polymerizable composition, an epoxy compound, an oxetane compound, a vinyl ether compound, or the like is mainly used.

  Of these, epoxy compounds, particularly alicyclic epoxy compounds, are advantageous in terms of reactivity and are often used as essential components.

  However, cationically polymerizable compounds generally have a problem that the curing rate is slow and the strength of the cured film is weak, and that they are easily affected by humidity, as compared with radically polymerizable compounds.

In recent years, inkjet recording methods can be used to produce images easily and inexpensively, so they have been applied to various printing fields such as photographs and various printing, as well as special printing such as marking and color filters. In view of the fact that recording on a recording medium having no quick drying and no ink absorption is possible, an ink jet method using an ink comprising an actinic ray curable composition is drawing attention. (For example, see Patent Documents 1 and 2.)
Also in these actinic radiation curable inkjet inks, an actinic radiation curable composition and an inkjet ink containing a cationically polymerizable compound are disclosed as inks having good curability and good ejection stability (for example, patents). As described above, however, there are problems in the curability under high humidity and the strength of the cured film, the adhesion to the substrate, the solvent resistance, and the water resistance.

In addition, the ink jet recording method using an organic pigment as a colorant has a great advantage over the ink jet recording method using a dye particularly in terms of light resistance, so indoor and outdoor posters, large signs, cars, glass, elevators, Application to wall and building decorations, as well as printing on fabrics, is expected, but when used in such applications, stronger film strength, adhesion to substrates, solvent resistance and water resistance Sex is required.
WO99 / 29787 Special Table 2000-504778 JP-A-8-143806 JP 2001-220526 A JP 2002-188025 A JP 2002-317139 A JP 2003-55449 A

  An object of the present invention is to provide an actinic ray curable ink for ink jet recording, which has high cured film strength, excellent adhesion to a substrate, is free from cracks, and provides a good image.

  The above problem could be solved by the following configuration.

(Claim 1)
In an actinic ray curable composition containing a cationic polymerizable compound and a photoacid generator, the peak temperature of the logarithmic decay rate measured with a pendulum viscoelasticity measuring device of a cured film immediately after curing by irradiation with actinic rays Is an actinic ray curable composition characterized in that the temperature is 120 ° C. or higher and 180 ° C. or lower.

(Claim 2)
The logarithmic decay rate at the peak temperature of the logarithmic decay rate is Δmax, and the logarithmic decay rate at 25 ° C. is Δ25 ° C., and 0.03 ≦ (Δmax−Δ25 ° C.) ≦ 0.2. The actinic ray curable composition as described.

(Claim 3)
The actinic ray curable composition according to claim 1 or 2, wherein at least one of the cationic polymerizable compounds is an alicyclic epoxy compound represented by the following general formula (A).

(Wherein, R ₁₀₀ represents a substituent, m0 is .L ₀ is r0 + 1 of which may from 1 to 15 carbon atoms include an oxygen atom or a sulfur atom in the main chain that represents a 1-3 .r0 representing 0-2 Represents a valent linking group or a single bond.)
(Claim 4)
The alicyclic epoxy compound represented by the general formula (A) is selected from at least one of the alicyclic epoxy compounds represented by the following general formula (I) or (II): The actinic ray curable composition according to any one of claims 1 to 3.

(Wherein, R ₁₀₁ represents a substituent, m1 represents 1 to 3 .r1 representing a 0 to 2 .L ₁ is r1 + 1 of which may from 1 to 15 carbon atoms include an oxygen atom or a sulfur atom in the main chain Represents a valent linking group or a single bond.)

(Wherein, R ₁₀₂ represents a substituent, m2 represents 1 to 3 .r2 representing a 0 to 2 .L ₂ is r2 + 1 of which may from 1 to 15 carbon atoms include an oxygen atom or a sulfur atom in the main chain Represents a valent linking group or a single bond.)
(Claim 5)
The actinic ray curable composition according to any one of claims 1 to 4, further comprising an oxetane compound.

(Claim 6)
An actinic radiation curable ink comprising a pigment in the actinic radiation curable composition according to any one of claims 1 to 5.

(Claim 7)
An actinic ray curable ink for ink jet recording, wherein the actinic ray curable ink according to claim 6 is used in an image forming method by an ink jet method.

(Claim 8)
An actinic ray curable ink jet recording ink according to claim 7 is jetted onto a recording material from an ink jet recording head, and printing is performed on the recording material, wherein the actinic ray curable ink is landed. After that, an actinic ray is irradiated for 0.001 to 1.0 seconds.

(Claim 9)
A printed matter produced by the image forming method according to claim 8.

  As a result of intensive studies on the conditions under which images and printed materials prepared using an ink comprising an actinic ray curable composition containing a cationic polymerizable compound and a photoacid generator can withstand various situations, Since the logarithmic decay rate peak temperature of the cured film cured by irradiating with actinic rays is 120 ° C. or higher and 180 ° C. or lower, the cured film has excellent strength and adhesion to the substrate, and is free from cracks. Has been found to be obtained.

  It was possible to provide an ink for ink jet recording, which is excellent in cured film strength and adhesiveness to a substrate, has no cracks, and provides a good image.

  Hereinafter, the present invention will be described in detail.

  The logarithmic decay rate peak temperature in the present invention is a numerical value representing the softening point of the resin matrix in the cured film, and more specifically, when the resin matrix transitions from a glass state in a low temperature region to a rubber state in a high temperature region. It represents the transition temperature. In addition, this peak temperature can be measured in the state where the cured film is laminated on the substrate, so that the adhesiveness between the substrate and the cured film is different from the dynamic viscoelasticity measurement measured only with the cured film. In addition, measurement in a thin film state is also possible, and the physical properties are closer to the actual configuration.

  The logarithmic decay rate peak temperature is considered to have a correlation with the bridge state of the main chain structure after crosslinking the above-mentioned cured layer, and if the logarithmic decay rate peak temperature is high, the bridge amount is high and the structure is hard. Moreover, if the logarithmic decay rate peak temperature is low, it is suggested that the bridge amount is low and the structure is brittle. In other words, when the main chain structure is hard, movement hardly occurs due to heat, and the logarithmic decay rate peak temperature becomes high.

  Therefore, the cured layer film cured by irradiating the actinic ray curable composition containing the cationic polymerizable compound and the photoacid generator in the present invention with an actinic ray is a logarithm measured using a rigid pendulum type physical property measuring instrument. It is necessary that the decay rate peak temperature is 120 ° C. or higher and 180 ° C. or lower. When the logarithmic decay rate peak temperature is lower than 120 ° C., the curing is insufficient, the cured film is brittle, and the substrate adhesion cannot be obtained. When the temperature is higher than 180 ° C., the cured film is hard and flexibility cannot be obtained, and cracking tends to occur when the curvature is applied.

  In the present invention, when the maximum logarithmic decay rate is Δmax and the logarithmic decay rate at 25 ° C. is Δ25 ° C., 0.03 ≦ (Δmax−Δ25 ° C.) ≦ 0.2 is preferable. The value of the logarithmic decay rate represents the crosslinked state of the cured product. As the temperature increases, the structure begins to move, causing a change in viscosity and increasing the logarithmic decay rate. The more moving structures, that is, the denser the bridge density, the higher the logarithmic decay rate and the higher the viscosity. When the logarithmic decay rate is higher than 0.2, the amount of crosslinking is dense and the viscosity is high and the handling is poor, and when it is lower than 0.03, the crosslinking density of polymerization is low and brittle.

  The logarithmic decay rate peak temperature is measured using a commercially available pendulum type viscoelasticity measuring apparatus. For the measurement in the present invention, for example, a rigid pendulum type physical property tester RPT-3000W, which is a pendulum type viscoelasticity measuring device manufactured by A & D, is used, FRB-100 is used as a rigid pendulum frame, and a round bar type cylinder is used as a measurement unit. Edge RBP-040 is used. As a measurement sample, a cured film provided with an arbitrary film thickness on a 50 μm-thick PET film is prepared, placed on a heating / cooling block, and RBP-040 is placed on the surface of the cured film. Next, while heating the measurement sample at a temperature rising temperature of 10 ° C./min to 20 to 200 ° C., vibration of the pendulum is started, the period of the free vibration of the pendulum is analyzed, and a logarithmic decay rate for each measurement temperature is obtained. . From this result, the temperature at which the logarithmic decay rate shows the maximum value is taken as the logarithmic decay rate peak temperature. In addition, when the peak temperature does not appear under these conditions, the measurement conditions can be arbitrarily changed.

  As the cationic polymerizable compound in the present invention, various known cationic polymerizable monomers can be used. For example, JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, JP-A-2001-220526 Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

  A preferable aromatic epoxide is a di- or polyglycidyl ether produced by the reaction of a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof and epichlorohydrin, such as bisphenol A or an alkylene oxide thereof. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or alkylene oxide adducts thereof, and novolak type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  The alicyclic epoxide can be obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. Cyclohexene oxide or cyclopentene oxide-containing compounds are preferred.

  Preferred aliphatic epoxides include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or Diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or its alkylene oxide adduct, polyethylene glycol or its alkylene oxide adduct Of polyalkylene glycols such as diglycidyl ether, polypropylene glycol or diglycidyl ether of its alkylene oxide adduct Glycidyl ether, and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  Among these epoxides, in view of fast curability, aromatic epoxides and alicyclic epoxides are preferable, and alicyclic epoxides are particularly preferable.

  Such an alicyclic epoxide has a structure represented by the general formula (A), (I) or (II).

In the general formula (A), (I) or (II), R ₁₀₀ , R ₁₀₁ , R ₁₀₂ represent a substituent. Examples of the substituent include a halogen atom (for example, a chlorine atom, a bromine atom, a fluorine atom, etc.), an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Etc.), an alkoxy group having 1 to 6 carbon atoms (for example, methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, tert-butoxy group, etc.), acyl group (for example, acetyl group) , Propionyl group, trifluoroacetyl group, etc.), acyloxy group (for example, acetoxy group, propionyloxy group, trifluoroacetoxy group, etc.), alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group, tert-butoxycarbonyl group, etc.) ), And the like. As the substituent, an alkyl group, an alkoxy group, and an alkoxycarbonyl group are preferable.

  m0, m1, and m2 represent 0 to 2, and 0 or 1 is preferable.

L ₀ is an r0 + 1 valent linking group or single bond having 1 to 15 carbon atoms which may contain an oxygen atom or a sulfur atom in the main chain, and L ₁ is a carbon number 1 to 1 which may contain an oxygen atom or a sulfur atom in the main chain. 15 represents an r1 + 1-valent linking group or a single bond, and L ₂ represents an R2 + 1-valent linking group or a single bond having 1 to 15 carbon atoms which may contain an oxygen atom or a sulfur atom in the main chain.

Examples of the divalent linking group having 1 to 15 carbon atoms which may contain an oxygen atom or a sulfur atom in the main chain include the following groups, and these groups and —O— group, —S— group, —CO— group, Examples include groups formed by combining a plurality of —CS— groups.
A methylene group [—CH ₂ —],
An ethylidene group [> CHCH ₃ ],
Isopropylidene [> C (CH ₃ ) ₂ ],
1,2-ethylene group [—CH ₂ CH ₂ —],
1,2-propylene group [—CH (CH ₃ ) CH ₂ —],
1,3-propanediyl group [—CH ₂ CH ₂ CH ₂ —],
2,2-dimethyl-1,3-propanediyl group [—CH ₂ C (CH ₃ ) ₂ CH ₂ —],
2,2-dimethoxy-1,3-propanediyl group [—CH ₂ C (OCH ₃ ) ₂ CH ₂ —],
2,2-dimethoxymethyl-1,3-propanediyl group [—CH ₂ C (CH ₂ OCH ₃ ) ₂ CH ₂ —],
1-methyl-1,3-propanediyl group [—CH (CH ₃ ) CH ₂ CH ₂ —],
1,4-butanediyl group [—CH ₂ CH ₂ CH ₂ CH ₂ —],
1,5-pentanediyl group [—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ —],
An oxydiethylene group [—CH ₂ CH ₂ OCH ₂ CH ₂ —],
A thiodiethylene group [—CH ₂ CH ₂ SCH ₂ CH ₂ —],
3-oxothiodiethylene group [—CH ₂ CH ₂ SOCH ₂ CH ₂ —],
3,3-dioxothiodiethylene group [—CH ₂ CH ₂ SO ₂ CH ₂ CH ₂ —],
1,4-dimethyl-3-oxa-1,5-pentanediyl group [—CH (CH ₃ ) CH ₂ O—CH (CH ₃ ) CH ₂ —],
3-oxopentanediyl group [—CH ₂ CH ₂ COCH ₂ CH ₂ —],
1,5-dioxo-3-oxapentanediyl group [—COCH ₂ OCH ₂ CO—],
4-oxa-1,7-heptanediyl group [—CH ₂ CH ₂ CH ₂ OCH ₂ CH ₂ CH ₂ —],
3,6-dioxa-1,8-octanediyl group [—CH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ —],
1,4,7-trimethyl-3,6-dioxa-1,8-octanediyl group [—CH (CH ₃ ) CH ₂ O—CH (CH ₃ ) CH ₂ OCH (CH ₃ ) CH ₂ —],
5,5-dimethyl-3,7-dioxa-1,9-nonanediyl group [—CH ₂ CH ₂ OCH ₂ C (CH ₃ ) ₂ CH ₂ OCH ₂ CH ₂ —],
5,5-dimethoxy-3,7-dioxa-1,9-nonanediyl group [—CH ₂ CH ₂ OCH ₂ C (OCH ₃ ) ₂ CH ₂ OCH ₂ CH ₂ —],
5,5-dimethoxymethyl-3,7-dioxa-1,9-nonanediyl group [—CH ₂ CH ₂ OCH ₂ C (CH ₂ OCH ₃ ) ₂ CH ₂ OCH ₂ CH ₂ —],
4,7-dioxo-3,8-dioxa-1,10-decandiyl group [—CH ₂ CH ₂ O—COCH ₂ CH ₂ CO—OCH ₂ CH ₂ —],
3,8-dioxo-4,7-dioxa-1,10-decandiyl group [—CH ₂ CH ₂ CO—OCH ₂ CH ₂ O—COCH ₂ CH ₂ —],
1,3-cyclopentanediyl group [-1,3-C ₅ H ₈ —],
1,2-cyclohexanediyl group [-1,2-C ₆ H _10- ],
1,3-cyclohexanediyl group [-1,3-C ₆ H _10- ],
1,4-cyclohexanediyl group [-1,4-C ₆ H _10- ],
2,5-tetrahydrofurandiyl group [2,5-C ₄ H ₆ O—],
p- phenylene _{[-p-C 6 H 4 -} ],
m- phenylene group _{[-m-C 6 H 4 -} ],
α, α′-o-xylylene group [—o—CH ₂ —C ₆ H ₄ —CH ₂ —],
α, α′-m-xylylene group [—m—CH ₂ —C ₆ H ₄ —CH ₂ —],
α, α′-p-xylylene group [—p—CH ₂ —C ₆ H ₄ —CH ₂ —],
Furan-2,5-diyl - bismethylene group _{[2,5-CH 2 -C 4 H} 2 O-CH 2 -],
A thiophene-2,5-diyl-bismethylene group [2,5-CH ₂ —C ₄ H ₂ S—CH ₂ —],
Isopropylidenebis -p- phenylene group _{[-p-C 6 H 4 -C} (CH 3) 2 -p-C 6 H 4 -].

  Examples of the trivalent or higher linking group include groups formed by removing as many hydrogen atoms as necessary from the divalent linking groups listed above, and an —O— group, —S— group, —CO— group, Examples include groups formed by combining a plurality of —CS— groups.

L ₀ , L ₁ and L ₂ may have a substituent. Examples of the substituent include a halogen atom (for example, a chlorine atom, a bromine atom, a fluorine atom, etc.), an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Etc.), an alkoxy group having 1 to 6 carbon atoms (for example, methoxy group, ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, tert-butoxy group, etc.), acyl group (for example, acetyl group) , Propionyl group, trifluoroacetyl group, etc.), acyloxy group (for example, acetoxy group, propionyloxy group, trifluoroacetoxy group, etc.), alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group, tert-butoxycarbonyl group, etc.) ), And the like. As the substituent, an alkyl group, an alkoxy group, and an alkoxycarbonyl group are preferable.

L ₀ , L ₁ and L ₂ are preferably divalent linking groups having 1 to 8 carbon atoms which may contain an oxygen atom or a sulfur atom in the main chain, and the main chain having 2 to 1 carbon atoms having only carbon. A valent linking group is more preferred.

  The molecular weight of the alicyclic epoxy compound used in the present invention is preferably in the range of 250 to 600. If the molecular weight is excessively large, the viscosity becomes high when ink is used, which is not suitable.

  Specific examples of preferred alicyclic epoxides represented by general formula (A), (I) or (II) are shown below, but the present invention is not limited thereto.

  As addition amount of an alicyclic epoxy compound, it is preferable to contain 10-80 mass%. If it is less than 10% by mass, the curability is remarkably changed depending on the curing environment (temperature, humidity). When it exceeds 80 mass%, the film | membrane physical property after hardening is weak, and is unpreferable. In the present invention, one type of alicyclic epoxy compound may be used alone, or two or more types may be used in appropriate combination.

  These alicyclic epoxy compounds may be produced by any method, for example, see Maruzen KK Publishing, 4th Edition Experimental Chemistry Course 20 Organic Synthesis II, 213, 1992, Ed. by Alfred Hasfner, The Chemistry of Heterocyclic compounds, Vol. 30, Advertisement, Small Ring Heterocycles part3, Oxilanes, John & Wiley and Sons, An Inc. No. 5, 42, 1986, Yoshimura, Adhesion, Vol. 30, No. 7, 42, 1986, JP-A No. 11-100388, JP-A No. 4-36263, JP-A No. 4-69360 and the like.

  These alicyclic epoxy compounds have higher safety (AMES, sensitization test, etc.) than conventional alicyclic epoxy compounds, and are excellent in sensitivity, photopolymerization initiator solubility, storage stability, and the like.

  In the present invention, alicyclic epoxy compounds other than the above general formula can be added to the extent that safety, reactivity, and storage are not impaired.

  Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl Pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -o- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

  Among these vinyl ether compounds, in consideration of curability, adhesion, and surface hardness, di- or trivinyl ether compounds are preferable, and divinyl ether compounds are particularly preferable. In the present invention, one of the above vinyl ether compounds may be used alone, or two or more thereof may be used in appropriate combination.

  In the present invention, it is preferable to contain at least one oxetane compound as a photopolymerizable compound for the purpose of suppressing shrinkage of the recording material during ink curing.

  The oxetane compound according to the present invention is a compound having an oxetane ring, and any known oxetane compound as introduced in JP-A Nos. 2001-220526 and 2001-310937 can be used.

  In the oxetane compound according to the present invention, when a compound having 5 or more oxetane rings is used, the viscosity of the ink composition becomes high, so that handling becomes difficult, and the glass transition temperature of the ink composition becomes high. The resulting cured product will not be sufficiently sticky. The compound having an oxetane ring used in the present invention is preferably a compound having 1 to 4 oxetane rings.

  Hereinafter, specific examples of preferable oxetane compounds according to the present invention will be described, but the present invention is not limited thereto.

  An example of the compound having one oxetane ring is a compound represented by the following general formula (1).

In the general formula (1), R ¹ is a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group or other alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, or an aryl group. , A furyl group or a thienyl group, particularly preferably a group having an aromatic ring such as a phenyl group, a benzyl group, a fluorobenzyl group, a methoxybenzyl group, or a phenoxyethyl group. R ² is an alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 2-methyl- C2-C6 alkenyl group such as 2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group, phenoxyethyl group, etc. A group having an aromatic ring, an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethylcarbonyl group, a propylcarbonyl group, and a butylcarbonyl group, an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethoxycarbonyl group, a propoxycarbonyl group, and a butoxycarbonyl group; Alkoxycarbonyl group, ethylcarbamoyl group, propylcarbamoyl group, butylcarbamoyl group, pentylcarbamoyl The number, etc. 2-6 N- alkylcarbamoyl group having a carbon etc., particularly preferably a phenyl group, a benzyl group, fluorobenzyl group, a group having an aromatic ring such as methoxybenzyl group or a phenoxyethyl group.

  As the oxetane compound used in the present invention, it is particularly preferable to use a compound having one oxetane ring because the resulting composition has excellent tackiness, low viscosity and excellent workability.

  An example of a compound having two oxetane rings includes a compound represented by the following general formula (2).

In the general formula (2), R ¹ is the same group as that in the general formula (1). R ³ is, for example, a linear or branched alkylene group such as an ethylene group, a propylene group or a butylene group, a linear or branched poly (alkyleneoxy) such as a poly (ethyleneoxy) group or a poly (propyleneoxy) group. ) Group, propenylene group, methylpropenylene group, butenylene group or other linear or branched unsaturated hydrocarbon group, alkylene group containing carbonyl group or carbonyl group, alkylene group containing carboxyl group, alkylene containing carbamoyl group A group having an aromatic ring such as a phenyl group, a benzyl group, a fluorobenzyl group, a methoxybenzyl group, or a phenoxyethyl group.

R ³ is a polyvalent group selected from the groups represented by the following general formulas (3), (4) and (5), particularly preferably represented by the following general formula (3) or (4). It is a compound.

In the general formula (3), R ⁴ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. An alkoxy group having 1 to 4 carbon atoms, a halogen atom such as a chlorine atom or a bromine atom, a nitro group, a cyano group, a mercapto group, a lower alkyl carboxyl group, a carboxyl group, or a carbamoyl group.

In the general formula (4), R ⁵ represents an oxygen atom, a sulfur atom, a methylene group, NH, SO, SO ₂ , C (CF ₃ ) ₂ , or C (CH ₃ ) ₂ .

In General formula (5), R < ⁶ > is a C1-C4 alkyl group, such as a methyl group, an ethyl group, a propyl group, a butyl group, or an aryl group. n is an integer of 0-2000. R ⁷ is a methyl group, an ethyl group, a propyl group, a butyl group having 1 to 4 carbon atoms, or an aryl group. R ⁷ may further include a group selected from the group represented by the following general formula (6).

In General formula (6), R < ⁸ > is a C1-C4 alkyl group, such as a methyl group, an ethyl group, a propyl group, a butyl group, or an aryl group. m is an integer of 0-100.

  An example of a compound having 3 to 4 oxetane rings is a compound represented by the following general formula (7).

In general formula (7), R ¹ has the same meaning as R ¹ in the general formula (1). As R ⁹ , for example, a branched alkylene group having 1 to 12 carbon atoms such as groups represented by the following A to C, a branched poly (alkyleneoxy) group such as a group represented by the following D, or the following E And branched polysiloxy groups such as those shown. j is 3 or 4.

In A above, R ¹⁰ is a lower alkyl group such as a methyl group, an ethyl group or a propyl group. Moreover, in said D, p is an integer of 1-10.

  Preferable specific examples of the oxetane compound used in the present invention include the following compounds.

  The production method of each compound having an oxetane ring described above is not particularly limited, and may be a conventionally known method, for example, Pattison (DB Pattison, J. Am. Chem. Soc., 3455, 79). (1957)) discloses a method for synthesizing an oxetane ring from a diol.

  In the present invention, it is preferable that a photoacid generator is contained in the cationically polymerizable composition.

  In the present invention, the blending amount of the photoacid generator is preferably in the range of 3.0 to 10.0% by mass based on the whole cationic polymerizable composition.

  As the photoacid generator, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), 187. To page 192). Examples of compounds suitable for the present invention are listed below.

First, B (C ₆ F ₅ ) ⁴⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salts of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, phosphonium, etc. be able to.

  Specific examples of onium compounds that can be used in the present invention are shown below.

  Secondly, sulfonated substances that generate sulfonic acid can be mentioned, and specific compounds thereof are exemplified below.

  Thirdly, halides that generate hydrogen halide can also be used, and specific compounds thereof are exemplified below.

  Fourthly, an iron allene complex can be mentioned.

In the present invention, among the above onium compounds, a photoacid generator of the triarylsulfonium salt type is particularly preferable because of its good storage stability, and the sulfonium salt is “active” as a compound taking into account the safety of its decomposition product. A sulfonium salt compound that does not generate benzene after irradiation with light is preferred. The sulfonium salt compound satisfies the above condition if it has a substituent on the benzene ring bonded to S ⁺ .

“Does not generate benzene after irradiation with actinic rays” means that benzene is not substantially generated. Specifically, an ink containing 5% by mass of a sulfonium salt (photoacid generator) in the ink composition is included. The amount of benzene generated when an image of a thickness of 15 μm and about 100 m ² is printed and the photoacid generator is sufficiently decomposed while the ink film surface is kept at 30 ° C. is irradiated. It means that there is very little or less than 5 μg.

  Preferred triarylsulfonium salts are represented by the following general formulas [1] to [4].

In the formula, R _{1 to} R ₁₇ each represent a hydrogen atom or a substituent, R _{1 to} R ₃ do not simultaneously represent a hydrogen atom, R _{4 to} R ₇ do not simultaneously represent a hydrogen atom, and R _{8 to} R ₁₁ do not represent hydrogen atoms at the same time, and R _{12 to} R ₁₇ do not represent hydrogen atoms at the same time. X represents a non-nucleophilic anionic residue.

The substituent represented by R _{1 to} R ₁₇ is preferably an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, or a hexyl group, Alkoxy groups such as methoxy group, ethoxy group, propyl group, butoxy group, hexyloxy group, decyloxy group, dodecyloxy group, acetoxy group, propionyloxy group, decylcarbonyloxy group, dodecylcarbonyloxy group, methoxycarbonyl group, ethoxycarbonyl Group, carbonyl group such as benzoyloxy group, phenylthio group, halogen atom such as fluorine, chlorine, bromine and iodine, cyano group, nitro group and hydroxy group.

X represents a non-nucleophilic anion residue, for example, a halogen atom such as F, Cl, Br, or I, B (C ₆ F ₅ ) ₄ , R ₁₈ COO, R ₁₉ SO ₃ , SbF ₆ , AsF ₆ , PF ₆ , BF _{4 and the} like. However, R ₁₈ and R ₁₉ are each an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group, a halogen atom such as fluorine, chlorine, bromine or iodine, a nitro group, a cyano group, a methoxy group or an ethoxy group. Represents an alkyl group or a phenyl group which may be substituted with an alkoxy group or the like. Among these, B (C ₆ F ₅ ) ₄ and PF ₆ are preferable from the viewpoint of safety.

  The above compounds can be obtained from THE CHEMICAL SOCIETY OF JAPAN Vol. 71 no. 11, 1998, as well as the photoacid generator described in “Organic Materials for Imaging”, edited by Organic Electronics Materials Research Group, Bunshin Publishing (1993), can be easily synthesized by a known method.

  In the present invention, the sulfonium salt represented by the general formulas [1] to [4] is particularly preferably at least one of the sulfonium salts selected from the following formulas [5] to [13]. X represents a non-nucleophilic anion residue and is the same as described above.

Examples of the compound include the following compounds in addition to X ⁻ being PF ₆ ^{— in} the formulas [5] to [13].

  Moreover, although the ink composition of the present invention is cured by irradiation with ultraviolet rays, a photosensitizer can be used in combination in order to perform the curing reaction more efficiently. Examples of such a photosensitizer include triethanolamine, methyldiethanolamine, triisopropanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, benzoic acid ( 2-dimethylamino) ethyl, 4-dimethylaminobenzoic acid (n-butoxy) ethyl, amines such as 4-dimethylaminobenzoic acid 2-ethylhexyl, cyanine, phthalocyanine, merocyanine, porphyrin, spiro compound, ferrocene, fluorene, fulgide , Imidazole, perylene, phenazine, phenothiazine, polyene, azo compound, diphenylmethane, triphenylmethane, polymethine acridine, coumarin, ketocoumarin, quinacridone, indigo, styryl, pyriri Compounds, pyromethene compounds, pyrazolotriazole compounds, benzothiazole compounds, barbituric acid derivatives, thiobarbituric acid derivatives, and the like, and further, European Patent No. 568,993, US Patent No. 4,508,811, The compounds described in JP-A-5,227,227, JP-A-2001-125255, JP-A-11-271969 and the like can also be used. The usage-amount of a photosensitizer has the preferable range of 0.01-10.00 mass% in actinic-light curable composition.

  In addition, radical polymerization compositions such as radical polymerizable or crosslinkable monomers, oligomers and polymers, radical polymerization initiators, and the like are used in combination with the above cationic polymerizable composition, In this case, as the radically polymerizable compound, known monomers, oligomers and polymers such as (meth) acrylate compounds and maleimide compounds can be used.

  In the present invention, an ink for ink jet recording can be formed by adding a coloring material to the photopolymerizable composition containing an alicyclic epoxy compound and a photoacid generator.

  When the photopolymerizable composition containing the alicyclic epoxy compound of the present invention and a photoacid generator is used as the ink for ink jet recording, the viscosity at 50 ° C. is obtained in order to obtain stable ejection properties as the ink for ink jet recording. It is preferable to set it as 10 mPa * s or less. In the case of 10 mPa · s or more, in order to obtain stable ejection, it is necessary to further heat the temperature of the recording head, and there is a possibility that deterioration with time due to head load and ink heating may occur. In order to adjust to such a viscosity, it is preferable to use the 3-position substituted oxetane compound as a low-viscosity reaction diluent. Furthermore, it is preferable that the alicyclic epoxy compound of the present invention is 50% by mass or less of the total ink.

  An acid multiplication agent can be added to the photopolymerizable composition of the present invention. Since the acid is further generated by the action of the acid by the photoacid generator, photopolymerization can be promoted.

  An acid proliferating agent is a compound that is substituted with a relatively strong acid residue and generates an acid by causing an elimination reaction relatively easily. Therefore, this elimination reaction can be greatly activated by an acid catalyzed reaction, which is stable in the absence of an acid, but can easily generate an acid in the presence of an acid. It is decomposed by an acid catalyst reaction to generate an acid (ZOH in the following general formula) again. One or more acids are increased in one reaction, and the reaction proceeds at an accelerated rate as the reaction proceeds. Since the generated acid itself induces self-decomposition, the strength of the acid generated here is 3 or less, particularly 2 or less, as an acid dissociation constant (pKa). A weaker acid cannot cause autolysis. Examples of such acids include dichloroacetic acid, trichloroacetic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, and triphenylphosphonic acid. Specifically, the following compounds can be exemplified. First, organic acid ester compounds represented by the following general formula [III] can be mentioned.

In the formula, A ₁ represents a C1 to C6 alkyl group or aryl group, A ₂ represents a C1 to C6 alkyl group, A ₃ represents a bis (p-alkoxyphenyl) methyl group, 2-alkyl-2 -A propyl group, a 2-aryl-2-propyl group, a cyclohexyl group or a tetrahydropyranyl group, and Z represents an acid residue represented by ZOH having an acid dissociation constant (pKa) of 3 or less.

  When an acid acts on this compound, the ester group is decomposed into a carboxylic acid, which further causes decarboxylation, and the acid (ZOH) is easily eliminated. Specific compounds are shown below.

  Secondly, organic acid esters having an acetal group or a ketal group represented by the following general formula [IV] can be mentioned.

In the formula, Z has the same meaning as described above, A ₄ is a hydrogen atom, an alkyl group or an aryl group, A ₅ and A _{6 form} a methyl group or an ethyl group, or both form an ethylene group or a propylene group, A ₇ represents a hydrogen atom or a methyl group.

  In this compound, acetal or ketal is decomposed by the action of an acid to form β-aldehyde or ketone, from which ZOH is easily eliminated. Specific compounds are shown below.

  Thirdly, organic acid esters represented by the following general formula [V] can be mentioned.

In the formula, Z has the same meaning as described above, D ₁ and D ₂ represent a hydrogen atom, a C1 to C6 alkyl group or an aryl group, D ₂ and D ₃ represent a C1 to C6 alkyl group, or both Represents an alkylene group or a substituted alkylene group which forms an alicyclic structure.

  It is presumed that this compound generates ZOH after the hydroxyl group is eliminated by an acid catalyst to form a carbocation and hydrogen moves. Specific compounds are shown below.

  Other examples include organic peroxides, such as ketone peroxides such as methyl ethyl ketone peroxide and methylcyclohexanone peroxide, acyl peroxides such as octanoyl peroxide and benzoyl peroxide, cumene hydroperoxide, and diisopropylbenzene hydroperoxide. Hydroperoxide etc. are also mentioned.

(Pigments, dispersants, various additives)
In the present invention, as a color material used for mixing with the photopolymerizable composition to form an actinic ray curable inkjet ink, a color material that can be dissolved or dispersed in the main component of the photopolymerizable compound can be used. From the viewpoint of weather resistance, a pigment is preferable.

  The pigments that can be preferably used in the present invention are listed below.

C. I. Pigment Yellow-1, 3, 12, 13, 14, 17, 42, 81, 83, 87, 95, 110, 109, 120, 128, 138, 151, 180, 185,
C. I. Pigment Orange-16, 36, 38,
C. I. Pigment Red-5, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 1, 63: 1, 122, 144, 146, 185, 101,
C. I. Pigment Violet-19, 23,
C. I. Pigment Blue-15: 1, 15: 3, 15: 4, 18, 60, 27, 29,
C. I. Pigment Green-7, 36,
C. I. Pigment White-6, 18, 21,
C. I. Pigment Black-7,
In the present invention, it is preferable to use white ink in order to improve the color concealment property on a transparent substrate such as a plastic film. In particular, in soft packaging printing and label printing, it is preferable to use white ink. However, from the viewpoints of the above-described ejection stability and the occurrence of curling and wrinkling of the recording material, the amount used is naturally limited.

  For the dispersion of the pigment, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, or the like can be used. It is also possible to add a dispersant when dispersing the pigment. As the dispersant, a polymer dispersant is preferably used, and examples of the polymer dispersant include Solsperse series manufactured by Avecia. Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. The dispersion medium is a solvent or a polymerizable compound. The actinic ray curable ink for ink jet recording used in the present invention is preferably solventless because it reacts and cures immediately after ink landing. If the solvent remains in the cured image, the solvent resistance deteriorates and the VOC of the remaining solvent arises. Therefore, it is preferable in view of dispersibility that the dispersion medium is not a solvent but a polymerizable compound, and among them, a monomer having the lowest viscosity is selected.

  The pigment is preferably dispersed so that the average particle diameter of the pigment particles is 0.08 to 0.5 μm, and the maximum particle diameter is 0.3 to 10 μm, preferably 0.3 to 3 μm. The selection of the dispersion medium, the dispersion conditions, and the filtration conditions are appropriately set. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

  In the ink according to the present invention, the color material concentration is preferably 1% by mass to 10% by mass of the entire ink.

  In the ink according to the present invention, various additives other than those described above can be used. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, and waxes can be added. In order to improve the adhesion with the recording medium, it is also effective to add a trace amount of organic solvent. In this case, it is effective to add in the range where the solvent resistance and VOC problems do not occur, and the amount used is in the range of 0.1 to 5%, preferably 0.1 to 3%. Further, a radical-cation hybrid actinic ray curable ink can be obtained by combining a radical polymerizable monomer and an initiator.

  In the present invention, a basic compound is preferably used. By containing the basic compound, not only the ejection stability becomes good, but also the generation of wrinkles due to curing shrinkage is suppressed even under low humidity.

  As the basic compound, any known compounds can be used, and typical examples include basic alkali metal compounds, basic alkaline earth metal compounds, and basic organic compounds such as amines.

  Examples of the basic alkali metal compound include alkali metal hydroxides (lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.), alkali metal carbonates (lithium carbonate, sodium carbonate, potassium carbonate, etc.), alkali metals. Alcoholate (sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, etc.).

  As the basic alkaline earth metal compound, alkaline earth metal hydroxides (magnesium hydroxide, calcium hydroxide, etc.), alkaline earth metal carbonates (magnesium carbonate, calcium carbonate, etc.), Examples include alkaline earth metal alcoholates (magnesium methoxide, etc.).

  Examples of the basic organic compound include amines and nitrogen-containing heterocyclic compounds such as quinoline and quinolidine. Among these, amines are preferable from the viewpoint of compatibility with the photopolymerization monomer, for example, octylamine, naphthylamine, Xylenediamine, dibenzylamine, diphenylamine, dibutylamine, dioctylamine, dimethylaniline, quinuclidine, tributylamine, trioctylamine, tetramethylethylenediamine, tetramethyl-1,6-hexamethylenediamine, hexamethylenetetramine and triethanolamine, etc. Is mentioned.

  The concentration when the basic compound is present is preferably in the range of 10 to 1000 ppm by mass, particularly 20 to 500 ppm by mass relative to the total amount of the photopolymerizable monomer. In addition, a basic compound may be used individually or may be used in combination of multiple.

  As a recording material that can be used in the present invention, in addition to ordinary uncoated paper, coated paper, etc., various non-absorbable plastics and films used for so-called soft packaging can be used. Examples thereof include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. As other plastics, polycarbonate, acrylic resin, ABS, polyacetal, PVA, rubbers and the like can be used. Moreover, it is applicable also to metals and glass. Among these recording materials, the structure of the present invention is effective particularly when an image is formed on a PET film, an OPS film, an OPP film, an ONy film, or a PVC film that can be shrunk by heat. These substrates are not only susceptible to curling and deformation of the film due to ink curing shrinkage and heat generation during the curing reaction, but also the ink film is difficult to follow the substrate shrinkage.

The surface energies of these various plastic films differ greatly, and it has been a problem in the past that the dot diameter after ink landing varies depending on the recording material. In the configuration of the present invention, high definition is good for a wide range of recording materials having a surface energy of 35 to 60 × 10 ⁻³ N / m, including OPP films having a low surface energy, OPS films, and PET having a relatively large surface energy. An image can be formed.

  In the present invention, it is more advantageous to use a long (web) recording material in terms of the cost of the recording material such as packaging cost and production cost, the production efficiency of the print, and the ability to cope with printing of various sizes. is there.

  In the image forming method of the present invention, the ink composition is ejected and drawn on a recording material by an ink jet recording method, and then the ink is cured by irradiation with an actinic ray such as ultraviolet rays.

  As the ink ejection conditions, it is preferable from the viewpoint of ejection stability that the recording head and ink are heated to 35 to 100 ° C. and ejected. Actinic radiation curable ink has a large viscosity fluctuation range due to temperature fluctuations, and the viscosity fluctuations directly affect the droplet size and droplet ejection speed, causing image quality degradation. It is necessary to keep. The control range of the ink temperature is set temperature ± 5 ° C., preferably set temperature ± 2 ° C., more preferably set temperature ± 1 ° C.

  Moreover, in this invention, it is preferable that the droplet amount discharged from each nozzle is 2-40 pl. In order to form a high-definition image, it is necessary for the amount of droplets to be in this range. However, when discharging with this amount of droplets, the aforementioned discharge stability becomes particularly severe, and an acid proliferation agent is essential. Become.

  In the image recording method of the present invention, the irradiation condition of the generated light is preferably actinic light irradiation within 0.001 to 2.0 seconds after ink landing, and more preferably 0.001 to 1.0. Seconds. In order to form a high-definition image, it is particularly important that the irradiation timing is as early as possible.

  As a method for irradiating actinic rays, the basic method is disclosed in JP-A-60-132767. According to this, the light source is provided on both sides of the recording head unit, and the recording head and the light source are scanned by the shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In US Pat. No. 6,145,979, as an irradiation method, a method using an optical fiber or a method of applying a collimated light source to a mirror surface provided on the side surface of a recording head unit and irradiating the recording unit with UV light is disclosed. ing. Any of these irradiation methods can be used in the image forming method of the present invention.

  In addition, irradiation with actinic rays is divided into two stages. First, actinic rays are irradiated by the above-described method within 0.001 to 2.0 seconds after ink landing, and further, actinic rays are irradiated after all printing is completed. The method is also a preferred embodiment. By dividing the irradiation of actinic rays into two stages, it is possible to further suppress the shrinkage of the recording material that occurs during ink curing.

In the present invention, the peak (maximum) intensity in the effective wavelength range for curing is 0.1 mW / cm ² or more, it is preferable to use actinic rays low illuminance of less than 1000 mW / cm ^2.

  Examples of light sources used in actinic ray irradiation include low pressure mercury lamps, high pressure mercury lamps, metal halide lamps, electrodeless UV lamps, excimer lasers, UV lasers, xenon flash lamps, insect traps, black lights, germicidal lamps, cold cathode tubes, There is a light emitting diode (LED), but the invention is not limited to these.

In the present invention, the peak irradiance in the effective wavelength range for curing is 50 mW / cm ² or more, it is also effective to use a 3000 mW / cm ² or less of active ray.

  Next, an ink jet recording apparatus (hereinafter simply referred to as a recording apparatus) that can be used in the present invention will be described.

  Hereinafter, a recording apparatus according to the present invention will be described with reference to the drawings as appropriate. Note that the recording apparatus in the drawings is only one aspect of the recording apparatus that can be preferably used in the present invention, and the present invention is not limited to the drawing of the recording apparatus exemplified here.

  FIG. 1 is a front view showing an example of a configuration of a main part used in a serial printing method in an ink jet recording apparatus that can be used in the present invention. The recording apparatus 1 includes a head carriage 2, a recording head 3, an irradiation unit 4, a platen unit 5, and the like. In the recording apparatus 1, the platen unit 5 is installed under the base material P. The platen unit 5 has a function of absorbing ultraviolet rays, and absorbs excess ultraviolet rays that have passed through the substrate P. As a result, a high-definition image can be reproduced very stably.

  The base material P is guided by the guide member 6 and moves from the near side to the far side in FIG. 1 by the operation of the conveying means (not shown). A head scanning unit (not shown) scans the recording head 3 held by the head carriage 2 by reciprocating the head carriage 2 in the Y direction in FIG.

  The head carriage 2 is installed on the upper side of the substrate P, and stores a plurality of recording heads 3 to be described later according to the number of colors used for image printing on the substrate P, with the discharge ports arranged on the lower side. The head carriage 2 is installed with respect to the main body of the recording apparatus 1 in such a manner that it can reciprocate in the Y direction in FIG. 1, and reciprocates in the Y direction in FIG. 1 by driving the head scanning means.

  In FIG. 1, the head carriage 2 is illustrated as accommodating the recording heads 3 of yellow (Y), magenta (M), cyan (C), and black (K). The number of colors of the recording head 3 housed in the head carriage 2 can be determined as appropriate.

  The recording head 3 directs the actinic ray curable ink supplied by the ink supply means (not shown) from the discharge port toward the substrate P by the operation of a plurality of discharge means (not shown) provided therein. To discharge. The actinic ray curable ink ejected by the recording head 3 is composed of a coloring material and the photopolymerizable composition (that is, containing an alicyclic epoxy compound, a photoacid generator, an initiator, etc.), It has the property of being cured by a cationic polymerization reaction when irradiated with ultraviolet rays.

  The recording head 3 has a certain region (landing possible region) on the substrate P during scanning of moving from one end of the substrate P to the other end of the substrate P in the Y direction in FIG. ), Actinic ray curable ink is ejected as ink droplets, and the ink droplets are landed on the landable area.

  The above scanning is performed as many times as necessary, and actinic ray curable ink is ejected toward one landable area, and then the substrate P is appropriately moved from the front to the back in FIG. While scanning by the scanning unit, the recording head 3 discharges actinic ray curable ink to the next landable area adjacent to the rearward direction in FIG.

  By repeating the above operation and ejecting the actinic ray curable ink from the recording head 3 in conjunction with the head scanning unit and the conveying unit, an image composed of an aggregate of actinic ray curable ink droplets is formed on the substrate P. Is done.

  The irradiation unit 4 includes an ultraviolet lamp that emits ultraviolet light in a specific wavelength region with stable exposure energy and a filter that transmits ultraviolet light of a specific wavelength. Here, as the ultraviolet lamp, those mentioned above can be applied, and a strip-shaped metal halide lamp, a cold cathode tube, a mercury lamp or a black light is preferable.

  The irradiation range by the irradiation unit 4 is substantially the same as the maximum range that can be set by the recording apparatus 1 among the landable regions in which the recording head 3 ejects actinic ray curable ink by a single scan driven by the head scanning unit. It is preferable to have a shape larger than the landable area.

  The irradiating means 4 is fixed on both sides of the head carriage 2 so as to be substantially parallel to the substrate P. When ink is ejected from the recording head as the head carriage 2 scans in the Y direction, the ink droplets ejected on the substrate are sequentially irradiated with ultraviolet rays by the irradiation means on the side opposite to the carriage moving direction. It is cured by receiving. In order to prevent the ink from being irradiated and cured before landing on the substrate, as described above, the illuminance of the ink ejecting section is designed to shield the entire recording head 3 or, in addition, the irradiation means 4 and the substrate P. The distance h2 between the ink discharge portion 31 of the recording head 3 and the substrate P is made smaller than the distance h1 (h1> h2), or the distance d between the recording head 3 and the irradiation means 4 is made larger (d is increased). It is effective to make adjustments. Further, it is more preferable to provide a bellows structure 7 between the recording head 3 and the irradiation means 4.

  Here, the wavelength of the ultraviolet rays irradiated by the irradiation means 4 can be changed as appropriate by replacing the ultraviolet lamp or filter provided in the irradiation means 4.

  As described above, in the serial printing method, the ink ejected from the recording head is 0.001 to 2.0 seconds after ink landing from the irradiation means attached to the carriage by scanning in the Y direction of the carriage, more preferably Actinic rays are irradiated between 0.001 and 1.0 seconds. In order to form a high-definition image, it is important that the irradiation timing is as early as possible. In addition, in the case of high-speed printing (printing), the carriage moves quickly, so that sufficient irradiation energy cannot be obtained. Insufficient curing.

  As described above, the serial printing method has been described as an example in FIG. 1, but in addition, a line head type ink jet recording apparatus as shown in FIG. 2 can be used.

  In FIG. 2, FIG. 2 shows a method (line head method) in which the recording head 19 is arranged in the width direction of the substrate 20 and actinic rays are irradiated from the printing and irradiation means 24 while conveying the recording medium.

  The present invention will be specifically illustrated by the following examples, but is not limited thereto.

<Actinic ray curable composition>
Actinic ray curable compositions 1 to 6 were prepared according to Table 1. The amount added represents parts by mass. Furthermore, the pigment dispersion and the following additives were added to each to obtain an actinic ray curable ink (cyan 1C to cyan 6C). Below, the mass part of the other composition added with respect to the actinic-light curable composition 100 is shown. The pigment dispersion was prepared by adding a high-concentration dispersion with oxetane (OXT221). At this time, OXT 221 added excessively was previously reduced so that the composition ratio of the polymerizable composition in the case of ink was not changed.

Actinic ray curable composition 100 parts by mass Pigment (Pigment Blue 15: 4) 3.5 parts by mass Pigment dispersant (PB822; manufactured by Ajinomoto Fine-Techno Co., Ltd., Ajisper PB822)
0.5 parts by mass Surfactant (F178K; manufactured by Dainippon Ink, MegaFuck F178K)
0.01 parts by weight Leveling agent (F1405; manufactured by Dainippon Ink, MegaFuck F1405)
0.01 part by weight Polymerization inhibitor (amine; N-ethyldiethanolamine) 0.15 part by weight

Celoxide 2021P: manufactured by Daicel Chemical Industries, epoxy resin OXT221: manufactured by Toa Gosei Co., Ltd., oxetane compound E4030: manufactured by Nippon Nippon Chemical Co., Ltd., epoxidized vegetable oil UVI6992: manufactured by Dow Chemical, triarylsulfonium salt (mixture of monocation and dication, active ingredient 50%. )
On the PET (polyethylene terephthalate) film, the cyan ink was applied with a wire bar so as to have a thickness of 3 μm, and the applied film was respectively subjected to a high-pressure mercury lamp (Integration Co., Ltd.) in an environment of 27 ° C. and 80% RH. (Made by: Vzero085, 140 W / cm setting) was passed 4 times at 400 mm / s and completely cured, and the following evaluation was performed.

<Logarithmic decay rate>
For the obtained cured film, the logarithmic decay rate immediately after curing was measured under the following conditions to obtain the logarithmic decay rate Δ25 ° C. at 25 ° C., the maximum value Δmax and the temperature at that time.

Measuring instrument: Rigid pendulum type physical property tester RPT-3000W
Frame type: FRB-100
Frame mass: 13g
Measuring part shape: Round bar type cylinder edge RBP-040
Inertia rate: 600gcm
Measurement temperature: 20-200 ° C
Temperature increase rate: + 10 ° C / min
<Film strength evaluation>
The surface of the obtained cured film was measured for scratch strength with a scratch strength tester HEIDON-18 (manufactured by HEIDON) using a 0.8 mmR sapphire needle as a measuring needle. For the measurement, a 10 cm scratch test at a constant load was performed three times, a limit load at which there was no scratched part to the support was defined as a scratch strength, and the strength of the film was evaluated from the measured values according to the following criteria.

○: Scratch strength is 200 g or more Δ: Scratch strength is 100 to less than 200 g ×: Scratch strength is less than 100 g <Evaluation of substrate adhesion>
About the obtained cured film, in accordance with JIS K 5400, 11 cuts were made vertically and horizontally at intervals of 1 mm on the printed surface, and 1 mm square grids were obtained. 100 samples were prepared, cellophane tape was applied on each cured film surface, quickly peeled off at an angle of 90 degrees, and the state of the cured film or grid remaining without peeling was evaluated according to the following criteria. .

○: No peeling of the printed image is observed even in the cross-cut test. Easily peel off with cello tape (registered trademark) <Evaluation of bending resistance>
The obtained cured film was evaluated for bending resistance according to the following criteria.

○: Can be bent following the substrate △: Cracks occur when bent ×: Film peels off from the crack surface <Image evaluation by inkjet>
In addition, the actinic ray curable composition No. 1 was used, and the pigments and the pigment dispersant were changed to the following, and inks of respective colors were produced in the same manner to obtain an inkjet ink set 1.

Yellow: Pigment yellow 180, 4 parts by mass, pigment dispersant RB822, 0.6 parts by mass (ink 1Y)
Magenta; Pigment Red 122, 4 parts by mass, pigment dispersant RB822, 0.3 parts by mass (ink 1M)
Black; carbon black, 3 parts by mass, pigment dispersant, RB822, 0.4 parts by mass (ink 1K)
Next, the above-described ink jet ink set 1 is loaded into the ink jet recording apparatus having the configuration shown in FIG. 1 provided with a piezo type ink jet nozzle, and full color image recording is performed on a PET film and synthetic paper (manufactured by YUPO Corporation, YUPO). Went. The ink supply system was composed of an ink tank, a supply pipe, a front chamber ink tank just before the head, a pipe with a filter, and a piezo head. The ink was insulated from the front chamber tank to the head portion and heated at 50 ° C. The piezo head was driven so that 2 to 15 pl multi-size dots could be ejected at a resolution of 720 × 720 dpi, and each ink was ejected continuously. After landing, it is cured instantaneously (less than 0.5 seconds after landing) by the lamp units on both sides of the carriage. The high pressure mercury lamp mentioned above was used as a light source. After recording, the total ink film thickness was measured and found to be in the range of 2.3 to 13 μm. In the present invention, dpi represents the number of dots per 2.54 cm. The inkjet image was formed in an environment of 27 ° C. and 80% RH according to the above method.

  The results are shown in Table 2.

  The sample of the present invention had good scratch resistance and substrate adhesion, and a good printed matter was obtained in which cracking did not occur even when bending or curvature was applied.

It is a front view which shows an example of a structure of the principal part of the inkjet recording device using a serial printing system. It is a figure which shows the printing system of the inkjet recording device using an in-line printing system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording device 2 Head carriage 3,19 Recording head 4,24 Irradiation means 5 Platen part 6 Guide member 7 Bellows structure P, 20 Base material

Claims (9)

In an actinic ray curable composition containing a cationic polymerizable compound and a photoacid generator, the peak temperature of the logarithmic decay rate measured with a pendulum viscoelasticity measuring device of a cured film immediately after curing by irradiation with actinic rays Is an actinic ray curable composition characterized in that the temperature is 120 ° C. or higher and 180 ° C. or lower. The logarithmic decay rate at the peak temperature of the logarithmic decay rate is Δmax, and the logarithmic decay rate at 25 ° C. is Δ25 ° C., and 0.03 ≦ (Δmax−Δ25 ° C.) ≦ 0.2. The actinic ray curable composition as described. The actinic ray curable composition according to claim 1 or 2, wherein at least one of the cationic polymerizable compounds is an alicyclic epoxy compound represented by the following general formula (A).

(Wherein, R ₁₀₀ represents a substituent, m0 is .L ₀ is r0 + 1 of which may from 1 to 15 carbon atoms include an oxygen atom or a sulfur atom in the main chain that represents a 1-3 .r0 representing 0-2 Represents a valent linking group or a single bond.) The alicyclic epoxy compound represented by the general formula (A) is selected from at least one of the alicyclic epoxy compounds represented by the following general formula (I) or (II): The actinic ray curable composition according to any one of claims 1 to 3.

(Wherein, R ₁₀₁ represents a substituent, m1 represents 1 to 3 .r1 representing a 0 to 2 .L ₁ is r1 + 1 of which may from 1 to 15 carbon atoms include an oxygen atom or a sulfur atom in the main chain Represents a valent linking group or a single bond.)

(Wherein, R ₁₀₂ represents a substituent, m2 represents 1 to 3 .r2 representing a 0 to 2 .L ₂ is r2 + 1 of which may from 1 to 15 carbon atoms include an oxygen atom or a sulfur atom in the main chain Represents a valent linking group or a single bond.) The actinic ray curable composition according to any one of claims 1 to 4, further comprising an oxetane compound. An actinic radiation curable ink comprising a pigment in the actinic radiation curable composition according to any one of claims 1 to 5. An actinic ray curable ink for ink jet recording, wherein the actinic ray curable ink according to claim 6 is used in an image forming method by an ink jet method. An actinic ray curable ink jet recording ink according to claim 7 is jetted onto a recording material from an ink jet recording head, and printing is performed on the recording material, wherein the actinic ray curable ink is landed. After that, an actinic ray is irradiated for 0.001 to 1.0 seconds. A printed matter produced by the image forming method according to claim 8.

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