JP2010174093A - Cationic polymerizable composition, actinic ray-curable inkjet ink and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cationic polymerizable composition which is excellent in curing sensitivity and weatherability of a formed image and exhibits good ejection stability from a recording head, and to provide actinic ray-curable inkjet ink and an image forming method using the same. <P>SOLUTION: The cationic polymerizable composition contains a hindered phenol-based compound (B) in a cationic polymerizable composition including a cationic polymerizable monomer and a photopolymerization initiator (A), wherein the content of the photopolymerization initiator (A) relative to the total mass is 1.0-2.5 mass% and the mass ratio of the photopolymerization initiator (A) to the hindered phenol-based compound (B), (A/B), is 1.0-5.0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel cationic polymerizable composition that is cured by irradiation with an actinic ray, an actinic ray curable inkjet ink containing the composition, and an image forming method using the same.

  Conventionally, curable compositions that are cured by active energy rays such as ultraviolet rays and electron beams or heat are various kinds of paints such as plastics, paper, woodwork and inorganic materials, adhesives, printing inks, printed circuit boards, and electrical insulation relations. It has been put to practical use. In recent years, printing inks, paints, adhesives and the like have been desired to further improve weather resistance and adhesion. Ink jet inks using these include photo-curable inks that are cured with actinic rays such as ultraviolet rays. The ink jet system using this photocurable ink has been attracting attention in recent years because it has a relatively low odor and can be recorded on a recording medium having no quick drying and no ink absorption. For example, JP-A-6-200204. In Japanese Patent Publication No. 2000-504778, an ultraviolet curable inkjet ink is disclosed.

  As these ultraviolet curable inks, inks using radically polymerizable compounds and inks using cationically polymerizable compounds are being studied because they do not suffer from the inhibition of polymerization by oxygen (for example, (See Patent Documents 1 to 4).

  Among the ultraviolet curable inks, inks containing a cationic curable compound are excellent in thin film curability and are used as coating agents, adhesives, and the like. Recently, it has begun to be used rapidly as an ink-jet ink.

  In image formation using an ultraviolet curable inkjet ink, an ultraviolet light source such as a high pressure mercury lamp or a halogen lamp is mainly used as an irradiation light source. On the other hand, in recent years, an LED light source as an ultraviolet light source with low irradiation energy is used as a light source for curing when forming an image on a recording material with low heat resistance because it has a long life and generates less heat rays. Being started. Furthermore, fluorescent lamps and low-pressure mercury lamps are attracting attention because they generate less heat rays. However, since these LEDs, fluorescent lamps, and low-pressure mercury lamps have lower light intensity than conventional high-pressure mercury lamps, the time required for curing tends to be long, so the high sensitivity of the inkjet ink containing the cation-curable compound to be applied. Is desired.

  On the other hand, in order to prevent unpleasant odor in the actinic ray curable composition and to improve abrasion resistance, bending resistance, bleed resistance, and storage stability, together with a photopolymerizable compound and a photopolymerization initiator, An actinic ray curable composition containing an odorant, a fragrance, or an antioxidant is disclosed (for example, see Patent Document 5). More specifically, by including an antioxidant together with a photopolymerizable compound and a photopolymerization initiator, an illegal polymerization reaction caused by oxygen or the like during storage can be achieved even when stored in a container with high water or air permeability. By preventing the progress, viscosity fluctuations and the like can be suppressed. The method described in Patent Document 5 is used only for the purpose of improving the weather resistance of the actinic ray curable composition during long-term storage, as described above, and the amount of addition of the antioxidant. However, as a range that does not affect the actinic ray curable composition, it remains in a very small amount range of 1.0% by mass or less from the viewpoint of improving the curing sensitivity of the actinic ray curable composition. No mention is made of the approach.

JP 2001-220526 A JP 2002-188025 A JP 2002-317139 A JP 2003-55449 A JP 2006-124636 A

  The present invention has been made in view of the above problems, and its purpose is a cationic polymerizable composition excellent in curing sensitivity and weather resistance of a formed image and having good emission stability from a recording head, and actinic ray curing. Another object is to provide an ink jet ink and an image forming method using the same.

  The above object of the present invention is achieved by the following configurations.

  1. In the cationically polymerizable composition containing the cationic polymerizable monomer and the photopolymerization initiator (A), the hindered phenol compound (B) is contained, and the content of the photopolymerization initiator (A) is 1 with respect to the total mass. The mass ratio (A / B) of the photopolymerization initiator (A) to the hindered phenol compound (B) is 1.0 mass% or more and 2.5 mass% or less. A cationically polymerizable composition, which is 0 or less.

  2. 2. The cationically polymerizable composition as described in 1 above, wherein the hindered phenol compound is a compound represented by the following general formula (1).

[Wherein R ¹ represents an alkyl group. R ² represents a hydrogen atom, an alkyl group or an acylamino group. R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a substituent capable of substituting on the benzene ring. ]
3. 3. The cationically polymerizable composition as described in 1 or 2 above, wherein the content of the hindered phenol compound (B) is 1.05% by mass or more and 2.0% by mass or less.

  4). Content of the said photoinitiator (A) is 2.0 mass% or more and 2.5 mass% or less, The cationically polymerizable composition of any one of said 1 to 3 characterized by the above-mentioned. .

  5. Any one of 1 to 4 above, wherein a mass ratio (A / B) of the photopolymerization initiator (A) to the hindered phenol compound (B) is 2.0 or more and 4.0 or less. The cationically polymerizable composition according to item 1.

  6). 6. The cationically polymerizable composition as described in any one of 1 to 5 above, which contains a pigment as a coloring material.

  7). An active energy ray-curable inkjet ink that is cured by irradiation with an actinic ray, which comprises the cationic polymerizable composition according to any one of 1 to 6 above.

  8). In the inkjet recording method, the actinic ray curable inkjet ink described in 7 above is ejected onto a recording medium, and then the actinic ray is irradiated to the emitted actinic ray curable inkjet ink to form a cured image. Image forming method.

  According to the present invention, there are provided a cationic polymerizable composition excellent in curing sensitivity and weather resistance of a formed image and having good emission stability from a recording head, an actinic ray curable inkjet ink, and an image forming method using the same. I was able to.

1 is a front view illustrating an example of a configuration of a main part of an ink jet recording apparatus applicable to the present invention.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventor contains a hindered phenol compound (B) in a cationic polymerizable composition containing a cationic polymerizable monomer and a photopolymerization initiator (A), The content of the photopolymerization initiator (A) with respect to the total mass is 1.0% by mass or more and 2.5% by mass or less, and the photopolymerization initiator (A) and the hindered phenol compound (B) Curing sensitivity of an image formed by a cationically polymerizable composition characterized by having a mass ratio (A / B) of 1.0 or more and 5.0 or less and an actinic ray curable inkjet ink using the same, and The present inventors have found that a cationically polymerizable composition having excellent weather resistance and good emission stability from a recording head, an actinic ray curable inkjet ink, and an image forming method using the same can be realized. It is.

  That is, in general, the curing sensitivity of the image formed by the cationic polymerizable composition or the actinic ray curable ink jet ink using the actinic ray is determined by the type of irradiation light source to be irradiated, the irradiation energy intensity associated therewith, and the irradiation time. It is governed by the type of cationically polymerizable compound, the amount of photopolymerizable compound added, and the like. However, when printing is performed on a thin plastic film, if irradiation energy necessary for curing is applied, deformation or the like occurs due to heat or the like, which limits the usable irradiation light source. For such a situation, a method using an LED, a fluorescent lamp, a low-pressure mercury lamp or the like as a low irradiation energy irradiation light source has been studied. However, it has been found that it is difficult to sufficiently cure the formed image to a desired degree of curing with these low irradiation energy light sources. As one method, a method of increasing the addition amount of the photopolymerizable compound was also conceived. However, as a result of the study by the present inventors, in the cationic polymerizable composition, only the photopolymerizable compound was simply increased. It was found that the desired degree of curing of the coating film could not be obtained.

  Based on the above situation, the present inventor has investigated the constitutional conditions of the cationic polymerizable composition capable of achieving a curing sensitivity capable of obtaining a sufficient cured film even using a low energy irradiation light source. In addition, by using an antioxidant having a specific structure, which is known to be used in a conventional cationic polymerizable composition, specifically, a hindered phenol compound in a specific range, It has been found that the curing sensitivity can be remarkably improved.

  Conventionally, the use of an antioxidant in a cationically polymerizable composition is described in, for example, Japanese Patent Application Laid-Open No. 2006-124636 (Patent Document 5). This is to prevent deterioration of the cationically polymerizable composition due to, and so on. In the present invention, the amount of the photopolymerization initiator that has been widely used in the past is kept in the range of 1.5 to 2.5 mass, and a hindered phenol compound is used as an antioxidant, and 0.2 of the photopolymerization initiator. By using it in the range of -1.0 times, for example, even if a low energy irradiation light source is used, the curing sensitivity of the cationic polymerizable composition can be sufficiently increased.

  Hereinafter, details of the cationic polymerizable composition and the actinic ray curable inkjet ink of the present invention will be described.

<Cationically polymerizable compound>
In the ink according to the present invention, various known cationic polymerizable monomers can be used as the cationic polymerizable compound (also referred to as a cationic polymerizable monomer), and among them, an epoxy compound and a compound having an oxetane ring are used. It is preferable to further contain a vinyl ether compound in addition to them.

[Epoxy compound]
As the epoxy compound according to the present invention, any of a monomer having an epoxy group and an oligomer thereof can be used. Specific examples include conventionally known aromatic epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. Hereinafter, the epoxy compound means a monomer or an oligomer thereof. As the oligomer in the present invention, a low molecular weight compound is preferable, and an oligomer having a molecular weight of less than 1000 is more preferable.

  A preferable aromatic epoxy compound 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, for example, bisphenol A or its Examples thereof include di- or polyglycidyl ethers of alkylene oxide adducts, hydrogenated bisphenol A or di- or polyglycidyl ethers of alkylene oxide adducts thereof, and novolak-type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the alicyclic epoxy compound, cyclohexene oxide 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. Alternatively, a cyclopentene oxide-containing compound is preferable, and specific examples include the compounds shown below.

  Preferred examples of the aliphatic epoxy compound include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include diglycidyl ether of ethylene glycol and diglycidyl ether of propylene glycol. Or polyglycidyl ether of polyhydric alcohol such as diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, glycerin or alkylene oxide adduct thereof, polyethylene glycol or alkylene oxide thereof Diglycidyl ether, poly (alkylene glycol) such as polypropylene glycol or diglycidyl ether of alkylene oxide adducts thereof Include diglycidyl ether of. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  In addition to these compounds, monoglycidyl ethers of aliphatic higher alcohols and monoglycidyl ethers of phenol and cresol, which are monomers having one oxirane ring in the molecule, can also be used. Among these epoxy compounds, in view of fast curability, aromatic epoxy compounds and alicyclic epoxy compounds are preferable, and alicyclic epoxy compounds are particularly preferable. In the present invention, one of the above epoxy compounds may be used alone, but two or more may be used in appropriate combination. When two or more alicyclic epoxy compounds are used in combination, the alicyclic epoxy compounds represented by the following general formulas (A), (B), and (C) substituted with a methyl group at the α-position or β-position And an alicyclic epoxy compound in which the α-position or β-position is unsubstituted are preferably used in combination.

  The alicyclic epoxy compound suitably used as the epoxy compound according to the present invention will be described.

  As an alicyclic epoxy compound applicable to this invention, the alicyclic epoxy compound represented by the following general formula (A), (B) or (C) can be mentioned.

In the general formula _{(A), R 100} represents a substituent, m0 represents 0-2. r0 represents 1-3. L ₀ represents a C 1-15 r 0 + 1 valent linking group or single bond that may contain an oxygen atom or a sulfur atom in the main chain.

In the general formula _{(B), R 101} represents a substituent, m1 represents 0-2. r1 represents 1-3. L ₁ represents a C 1-15 r 1 + 1 valent linking group or single bond which may contain an oxygen atom or a sulfur atom in the main chain.

In the general formula _{(C), R 102} represents a substituent, m2 represents 0-2. r2 represents 1-3. L ₂ represents a linking group or a single bond r2 + 1 valent oxygen atoms or from 1 to 15 carbon atoms which may contain a sulfur atom in the main chain.

In the general formulas (A), (B), and (C), R ₁₀₀ , R ₁₀₁ , and R ₁₀₂ represent a substituent. Examples of the substituent include a halogen atom (for example, chlorine atom, bromine atom, fluorine Atoms), an alkyl group having 1 to 6 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, 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, t-butoxy group, etc.), acyl group (for example, acetyl group, propionyl group, trifluoroacetyl group, etc.), acyloxy group (for example, acetoxy group, propionyl group) Oxy group, trifluoroacetoxy group, etc.), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, t-butoxycarbonyl) Group). As the substituent, an alkyl group, an alkoxy group, and an alkoxycarbonyl group are preferable.

  m0, m1, and m2 represent an integer of 0 to 2, and 0 or 1 is preferable. M0, m1, and m2 may be different within the same molecule.

L ₀ is an r0 + 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, 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 r1 + 1 valent connecting group or a single bond of, L ₂ represents a linking group or a single bond r2 + 1 valent oxygen atoms or from 1 to 15 carbon atoms which may contain 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. , A group formed by combining a plurality of —CS— groups.

Methylene group; [—CH ₂ —]
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; [- 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 —]
Oxydiethylene group; [—CH ₂ CH ₂ OCH ₂ CH ₂ —]
Thiodiethylene group; [—CH ₂ CH ₂ SCH ₂ CH ₂ —]
3-oxo thiodiethylene _{group; [- CH 2 CH 2 SOCH} 2 CH 2 -]
3,3-dioxo-thiodiethylene _{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-dimethoxy-methyl-3,7-dioxa-1,9-Nonanjiiru _{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-cyclopentane-diyl _{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; [- 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 —]
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 a group formed by removing as many hydrogen atoms as necessary from the divalent linking groups listed above, an —O— group, an —S— group, and a —CO— group. , A group formed by combining a plurality of —CS— groups.

L ₀ , L ₁ and L ₂ may each have a substituent. Examples of the substituent include a halogen atom (for example, chlorine atom, bromine atom, fluorine atom, etc.), an alkyl group having 1 to 6 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, 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, t-butoxy group, etc.), acyl group (for example, acetyl group, Propionyl group, trifluoroacetyl group, etc.), acyloxy group (eg, acetoxy group, propionyloxy group, trifluoroacetoxy group, etc.), alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group, t-butoxycarbonyl group, etc.), etc. Can be mentioned. As the substituent, an alkyl group, an alkoxy group, and an alkoxycarbonyl group are preferable. L ₀ , L ₁ and L ₂ are each preferably a divalent linking group 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 1 to 5 carbon atoms consisting only of carbon. The divalent linking group is more preferable.

  In the present invention, a photopolymerizable compound includes a compound having an oxetane ring and an alicyclic epoxy compound having two or more ester bonds. A compound represented by any one of the following general formulas (D) and (E) is preferable.

In the above general formula (D), R ₂₀₀ represents an aliphatic group other than the α and β positions of the oxirane ring, and m3 represents 0 to 2. X ₁ represents — (CH ₂ ) _n0 — or — (O) _n0 —, and n0 represents 0 or 1. p1 and q1 each represents 0 or 1 and are not 0 at the same time. r3 represents 1-3. L ₃ represents a linking group or a single bond having an r3 + 1 valent branched structure having 1 to 15 carbon atoms, which may contain an oxygen atom or a sulfur atom in the main chain.

In the above general formula (E), R ₂₀₁ represents an aliphatic group other than the α and β positions of the oxirane ring, and m4 represents 0 to 2. X ₂ represents — (CH ₂ ) _n1 — or — (O) _n1 —, and n1 represents 0 or 1. p2 and q2 each represent 0 or 1, and are not 0 at the same time. r4 represents 1-3. L ₄ represents a linking group or a single bond having an r4 + 1-valent branched structure having 1 to 15 carbon atoms, which may contain an oxygen atom or a sulfur atom in the main chain.

In said formula, _R200 , _R201 represents an aliphatic group. Examples of the aliphatic group include an alkyl group having 1 to 6 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, etc.), and a cycloalkyl group having 3 to 6 carbon atoms (for example, cyclopropyl group). Group, cyclobutyl group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group having 1 to 6 carbon atoms (for example, vinyl group, 1-propenyl group, 2-propenyl group, 2-butenyl group, etc.), carbon number 1 To 6 alkynyl groups (for example, acetylenyl group, 1-propynyl group, 2-propynyl group, 2-butynyl group, etc.). Preferably it is a C1-C3 alkyl group, and a methyl group and an ethyl group are more preferable.

  m3 and m4 represent 0 to 2, and preferably 1 or more.

X ₁ represents — (CH ₂ ) _n0 — or — (O) _n0 —, and X ₂ represents — (CH ₂ ) _n1 — or — (O) _n1 —. n0 and n1 represent 0 or 1, and when n0 and n1 are 0, it represents that X ₁ and X ₂ do not exist.

  m3 + n0 or m4 + n1 is preferably 1 or more.

L ₃ may include a linking group or a single bond having an R3 + 1-valent branched structure having 1 to 15 carbon atoms which may contain an oxygen atom or a sulfur atom in the main chain, and L ₄ may contain an oxygen atom or a sulfur atom in the main chain A linking group or a single bond having an r4 + 1 valent branched structure having 1 to 15 carbon atoms is represented. 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. , A group formed by combining a plurality of —CS— groups.

Ethylidene group; [> CHCH ₃ ]
Isopropylidene; [> C (CH ₃ ) 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-dimethyl-3-oxa-1,5-pentanediyl group; [—CH (CH ₃ ) CH ₂ OCH (CH ₃ ) CH ₂ —]
1,4,7-trimethyl-3,6-dioxa-1,8-octanediyl group; [—CH (CH ₃ ) CH ₂ OCH (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 —]
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 a group formed by removing as many hydrogen atoms as necessary from the divalent linking groups listed above, an —O— group, an —S— group, and a —CO— group. , A group formed by combining a plurality of —CS— groups.

L ₃ and L ₄ may each have a substituent. Examples of the substituent include a halogen atom (eg, chlorine atom, bromine atom, fluorine atom, etc.), an alkyl group having 1 to 6 carbon atoms (eg, methyl group, ethyl group, propyl group, isopropyl group, 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, t-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 (for example, methoxycarbonyl group, ethoxycarbonyl group, t- Butoxycarbonyl group, etc.). As the substituent, a halogen atom, an alkyl group, and an alkoxy group are preferable.

  An example of the alicyclic epoxy compound represented by the general formulas (A), (B), (C), (D), and (E) is shown below.

  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 changes remarkably depending on the curing environment (temperature, humidity) and cannot be used. If it exceeds 80% by mass, the film properties after curing are weak and cannot be used. 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. 5, No. 5, Advertisement, Small Ring Heterocycles Part 3, Oxilanes, John & Wiley and Sons, An Inc. 42, 1986, Yoshimura, Adhesion, Vol. 30, No. 7, 42, 1986, Japanese Patent Application Laid-Open No. 11-1000037, Japanese Patent No. 2906245, Japanese Patent No. 2926262, and the like.

  In the cationically polymerizable composition of the present invention, an epoxidized fatty acid ester or an epoxidized fatty acid glyceride can also be contained as an epoxy compound.

  By using epoxidized fatty acid ester or epoxidized fatty acid glyceride in combination with oxetane compound / alicyclic epoxy compound system, it is not only preferable from the viewpoint of safety and environment such as AMES and sensitization, skin irritation, odor, etc. Conventional problems such as generation of wrinkles due to curing shrinkage and poor curability and dischargeability can be solved depending on the curing environment (temperature, humidity).

  The epoxidized fatty acid ester and epoxidized fatty acid glyceride that can be used in the present invention are not particularly limited as long as an epoxy group is introduced into the fatty acid ester or fatty acid glyceride.

  The epoxidized fatty acid ester is produced by epoxidizing an oleic acid ester, and examples thereof include methyl epoxy stearate, butyl epoxy stearate, octyl epoxy stearate and the like. Similarly, epoxidized fatty acid glyceride is produced by epoxidizing soybean oil, linseed oil, castor oil and the like, and epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil and the like are used.

[Compound having oxetane ring]
As a compound having an oxetane ring applicable to the cationic polymerizable composition of the present invention, examples of monofunctional oxetane include, for example, 3-ethyl-3-hydroxymethyloxetane, 3- (meth) allyloxymethyl-3 -Ethyloxetane, (3-ethyl-3-oxetanylmethoxy) methylbenzene, 4-fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, 4-methoxy- [1- (3-ethyl- 3-oxetanylmethoxy) methyl] benzene, [1- (3-ethyl-3-oxetanylmethoxy) ethyl] phenyl ether, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3- Ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl-3-io) Cetanylmethyl) ether, 2-ethylhexyl (3-ethyl-3-oxetanylmethyl) ether, ethyldiethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclo Pentenyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromophenyl (3 -Ethyl-3-oxetanylmethyl) ether, 2-tetrabromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether, tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2 Tribromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl (3-ethyl-3-oxetanylmethyl) ether, butoxyethyl (3-ethyl-3-oxetanylmethyl) ether, pentachlorophenyl (3-ethyl-3-oxetanylmethyl) ether, pentabromophenyl (3-ethyl-3-oxetanylmethyl) ether, bornyl (3-ethyl-3-oxetanyl) Methyl) ether and the like.

  Examples of the polyfunctional oxetane include 3,7-bis (3-oxetanyl) -5-oxa-nonane, 3,3 ′-(1,3- (2-methylenyl) propanediylbis (oxymethylene)) bis. -(3-ethyloxetane), 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, 1, 3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenylbis (3-ethyl-3-oxetanylmethyl) ether, tri Ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol bis (3-ethyl) -3-oxetanylmethyl) ether, tricyclodecanediyldimethylene (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris (3-ethyl-3-oxetanylmethyl) ether, 1,4-bis (3- Ethyl-3-oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis (3-ethyl-3 -Oxetanylmethyl) ether, polyethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol pentakis (3-ethyl) 3-oxetanylmethyl) ether, dipentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol pentakis ( 3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropanetetrakis (3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, PO-modified bisphenol A bis ( 3-ethyl-3-oxetanylmethyl) ether, EO-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, PO-modified hydrogenated bisphenol A bis (3-ethyl) And polyfunctional oxetanes such as ru-3-oxetanylmethyl) ether and EO-modified bisphenol F (3-ethyl-3-oxetanylmethyl) ether.

  In the present invention, a monofunctional oxetane compound or a bifunctional oxetane compound is preferable from the viewpoint of reducing the viscosity of the cationic polymerizable composition. Moreover, it is preferable to use together the said alicyclic epoxy compound and oxetane compound as a cation polymerizable monomer.

[Vinyl ether compound]
Any known vinyl ether compound can be used in combination as the compound having a vinyl ether structure applicable to the cationically polymerizable composition of the present invention.

  Examples of monofunctional vinyl ethers used in the present invention include, for example, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, Cyclohexylmethyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether , Methoxy polyethylene Recall vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, Examples include chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, and the like.

  Examples of polyfunctional vinyl ethers include, for example, ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide. Divinyl ethers such as divinyl ether; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hex Vinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide-added penta And polyfunctional vinyl ethers such as erythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.

  As a cation polymerizable monomer composition in the cation polymerizable composition of the present invention, the alicyclic epoxy compound is in the range of 10 to 50% by mass and the compound having an oxetane ring is 40 to 80% by mass with respect to the total mass of the cation polymerizable monomer. %, Other cationically polymerizable monomers such as vinyl ether compounds are preferably used in the range of 0 to 40% by mass.

<< Photopolymerization initiator: Cationic polymerization initiator >>
In the present invention, as the photopolymerization initiator, all known photopolymerization initiators described in “Application and Market of UV / EB Curing Technology” (CMC Publishing Co., Ltd., edited by Yoneho Tabata / edited by Radtech Research Association), etc. Can be used.

  In the present invention, it is preferable to use a photoacid generator as a photopolymerization initiator. 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, diazonium, ammonium, iodonium, sulfonium, aromatic onium compounds such as phosphonium ^{_{B (C 6 F 5) 4}} -, PF 6 -, AsF 6 -, SbF 6 -, CF 3 SO 3 - and salts be able to. The onium salt is preferably a sulfonium salt or an iodonium salt.

  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 particular, in the cationically polymerizable composition of the present invention, the photoacid generator is preferably a compound containing a triarylsulfonium salt.

  The content of the photoacid generator is characterized by being added in the range of 1.0% by mass to 2.5% by mass with respect to the total mass of the cationic polymerizable composition of the present invention, more preferably 2. It is 0 mass% or more and 2.5 mass% or less.

《Hindered phenol compounds》
In the cationically polymerizable composition of the present invention, the hindered phenol compound is contained together with the photopolymerization initiator, and the mass ratio (A / B) of the photopolymerization initiator (A) and the hindered phenol compound (B). Is in the range of 1.0 or more and 5.0 or less, preferably the mass ratio (A / B) is 1.5 or more and 4.0 or less.

  Moreover, as content of the hindered phenol type compound with respect to the total mass of a cationically polymerizable composition, it is preferable to add with comparatively high concentration of 1.05 mass% or more and 2.0 mass% or less.

  As described above, a relatively high concentration of a hindered phenol compound is added, and the concentration of the photopolymerization initiator is 1.0% by mass or more and 2.5% by mass or less. With this configuration, sufficient curing sensitivity can be obtained even if a relatively low-energy LED, fluorescent lamp, low-pressure mercury lamp, or the like is used as the irradiation light source, so a high-definition image can be obtained even for a thin film with low heat resistance. Can be formed. Therefore, in the present invention, it has been found that a hindered phenol compound can exhibit a synergistic effect as a curing accelerator in addition to a conventionally known antioxidant.

  Hereinafter, the details of the hindered phenol compound according to the present invention will be described.

  The hindered phenolic compound as used in the present invention has a substituent other than a hydrogen atom at both of two ortho positions, or at least one of the two ortho positions is a hydrogen atom, and the other one shows steric hindrance. It is a phenol compound having a substituent.

  In the present invention, the hindered phenol compound is preferably a compound represented by the general formula (1). Hereinafter, the detail of the hindered phenol type compound represented by General formula (1) is demonstrated.

In the general formula (1), R ¹ represents an alkyl group. R ² represents a hydrogen atom, an alkyl group or an acylamino group. R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a substituent that can be substituted on the benzene ring.

In the general formula (1), when R ² is a substituent other than a hydrogen atom, R ¹ represents an alkyl group. As an alkyl group, a C1-C30 alkyl group is preferable, and the alkyl group may be unsubstituted or may have a substituent. Specific examples of the unsubstituted alkyl group include methyl group, ethyl group, butyl group, octyl group, isopropyl group, tert-butyl group, tert-octyl group, tert-amyl group, sec-butyl group, cyclohexyl group, 1- A methyl-cyclohexyl group and the like are preferable, and a group sterically larger than the isopropyl group (for example, isopropyl group, isononyl group, tert-butyl group, tert-amyl group, tert-octyl group, cyclohexyl group, 1-methyl-cyclohexyl group) , 1-benzylcyclohexyl group, adamantyl group, etc.), among which a tertiary alkyl group is more preferable. When R ¹ has a substituent, examples of the substituent include a halogen atom, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, an acyloxy group, and an oxycarbonyl. Group, carbamoyl group, sulfamoyl group, sulfonyl group, phosphoryl group.

R ² is a hydrogen atom, an alkyl group or an acylamino group having 1 to 30 carbon atoms having 1 to 30 carbon atoms, the alkyl group has the same meaning as the alkyl groups described in R ^1. The acylamino group may be unsubstituted or substituted, and specific examples include an acetylamino group, an alkoxyacetylamino group, and an aryloxyacetylamino group. R ² is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms, and specific examples include a methyl group, an isopropyl group, and a t-butyl group. R ³ represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, and the alkyl group has the same meaning as the alkyl group described for R ¹ . R ³ is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms, and specific examples include a methyl group, an isopropyl group, and a t-butyl group. Further, it is preferable that one of R ² or R ³ is a hydrogen atom.

R ⁴ represents a group that can be substituted on the benzene ring, and is a halogen atom, an alkyl group having 1 to 30 carbon atoms, an aryl group having 6 to 36 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, or an acylamino having 1 to 30 carbon atoms. Group, C 0-30 sulfonamido group, C 1-30 acyl group, C 1-30 carbamoyl group, C 0-30 sulfamoyl group, C 2-30 alkoxycarbonyl group, carbon Examples thereof include sulfonyl groups of 1 to 30. R ⁴ is preferably a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms or an oxycarbonyl group having 2 to 30 carbon atoms, and more preferably an alkyl group having 1 to 24 carbon atoms. Examples of the substituent of the alkyl group include an aryl group, an amino group, an alkoxy group, an oxycarbonyl group, an acylamino group, an acyloxy group, an imide group, and a ureido group, and more preferable examples include an aryl group, an amino group, an oxycarbonyl group, and an alkoxy group. preferable.

  Hereinafter, although the specific example of the hindered phenol type compound which concerns on this invention is shown, the compound which can be used by this invention is not limited to these.

  In addition to the above-mentioned compounds, the hindered phenol compounds applicable to the present invention include European Patent No. 803764, Japanese Patent Laid-Open No. 50-22135, Japanese Patent Laid-Open No. 50-36110, Japanese Patent Laid-Open No. Examples thereof include compounds described in JP-A-52-84727 and JP-A-6-3793.

<Pigment>
In the cationically polymerizable composition according to the present invention, it is preferable to contain a pigment as a coloring material.

  Examples of pigments applicable to the present invention are listed below.

C. I Pigment Yellow-1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 109, 114, 120, 128, 129, 138, 150, 151, 154, 155, 180, 185, 213
C. I Pigment Orange-16, 36, 38,
C. I Pigment Red-5, 7, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 1, 63: 1, 101, 112, 122, 123, 144, 146, 168, 184, 185, 202,
C. I Pigment Violet-19, 23,
C. I Pigment Blue-1, 2, 3, 15: 1, 15: 2, 15: 3, 15: 4, 18, 22, 27, 29, 60,
C. I Pigment Green-7, 36,
C. I Pigment White-6, 18, 21,
C. I Pigment Black-7, and the like.

  In the present invention, the colorant concentration is preferably 1% by mass to 10% by mass of the entire cationic polymerizable composition.

  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.

  Further, a dispersing agent can be added when dispersing the pigment. As the dispersant, a polymer dispersant is preferably used, and examples of the polymer dispersant include Avecia's Solsperse series and Ajinomoto Fine-Techno's PB series.

  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 formed using a solvent or a cationic polymerizable compound. However, the cationic polymerizable composition of the present invention is preferably solvent-free 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 0.2 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 of the pigment particles, clogging of nozzles in the ink jet recording head can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

《Other additives》
For the cationic polymerizable composition or actinic ray curable inkjet ink of the present invention, for example, a surfactant, a leveling additive, a matting agent, a slipping agent, a polyester resin for adjusting film physical properties, Polyurethane resins, vinyl resins, acrylic resins, rubber resins, and waxes can be added. In addition, for the purpose of improving storage stability, any known basic compound can be used, but representative examples include basic alkali metal compounds, basic alkaline earth metal compounds, amines and other basic organic compounds. Etc.

[Basic compounds]
In the present invention, a basic compound can be used from the viewpoint of improving ejection stability.

  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.

  Basic alkali metal compounds include alkali metal hydroxides (lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.), alkali metal carbonates (lithium carbonate, sodium carbonate, potassium carbonate, etc.), alkali metal alcoholates. (Sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, etc.).

  Similarly, basic alkaline earth metal compounds include alkaline earth metal hydroxides (magnesium hydroxide, calcium hydroxide, etc.), alkali metal carbonates (magnesium carbonate, calcium carbonate, etc.), and alkali 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, 2- (methyl And amino) ethanol and triethanolamine.

  The concentration when the basic compound is present is preferably in the range of 10 to 50000 ppm by mass, particularly 100 to 5000 ppm by mass, based on the total amount of the cationic polymerizable monomer. In addition, a basic compound may be used individually or may be used in combination of multiple.

[Sensitizer]
The cationic polymerizable composition of the present invention is selected from a hydroxyl group as a substituent, a polycyclic aromatic compound having at least one aralkyloxy group or an alkoxy group which may be substituted, a carbazole derivative, a phenothiazine derivative, and a thioxanthone derivative. At least one compound can be contained as a sensitizer. By containing these, the dischargeability and curability due to changes in the environment (temperature, humidity) are stabilized, and a high-definition image can be stably formed.

  As the polycyclic aromatic compound that can be used in the present invention, naphthalene derivatives, anthracene derivatives, chrysene derivatives, and phenanthrene derivatives are preferable. As an alkoxy group which is a substituent, a C1-C18 thing is preferable and a C1-C8 thing is especially preferable.

  As the aralkyloxy group, those having 7 to 10 carbon atoms are preferable, and benzyloxy groups and phenethyloxy groups having 7 to 8 carbon atoms are particularly preferable.

  Specific examples include 1-naphthol, 2-naphthol, 1-methoxynaphthalene, 1-stearyloxynaphthalene, 2-methoxynaphthalene, 2-dodecyloxynaphthalene, 4-methoxy-1-naphthol, glycidyl-1-naphthyl ether. 2- (2-naphthoxy) ethyl vinyl ether, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,7-dimethoxynaphthalene, 1,1 ′ -Thiobis (2-naphthol), 1,1'-bi-2-naphthol, 1,5-naphthyl diglycidyl ether, 2,7-di (2-vinyloxyethyl) naphthyl ether, 4-methoxy-1-naphthol ESN-175 (Epoxy resin manufactured by Nippon Steel Chemical Co., Ltd.) The series, naphthalene derivatives such as condensates of naphthol derivatives and formalin, 9,10-dimethoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, 2-tbutyl-9,10-dimethoxyanthracene, 2,3- Dimethyl-9,10-dimethoxyanthracene, 9-methoxy-10-methylanthracene, 9,10-diethoxyanthracene, 2-ethyl-9,10-diethoxyanthracene, 2-tbutyl-9,10-diethoxyanthracene 2,3-dimethyl-9,10-diethoxyanthracene, 9-ethoxy-10-methylanthracene, 9,10-dipropoxyanthracene, 2-ethyl-9,10-dipropoxyanthracene, 2-tbutyl-9 , 10-dipropoxyanthracene, 2,3-dimethyl 9,10-dipropoxyanthracene, 9-isopropoxy-10-methylanthracene, 9,10-dibenzyloxyanthracene, 2-ethyl-9,10-dibenzyloxyanthracene, 2-tbutyl-9,10-di Benzyloxyanthracene, 2,3-dimethyl-9,10-dibenzyloxyanthracene, 9-benzyloxy-10-methylanthracene, 9,10-di-α-methylbenzyloxyanthracene, 2-ethyl-9,10- Di-α-methylbenzyloxyanthracene, 2-tbutyl-9,10-di-α-methylbenzyloxyanthracene, 2,3-dimethyl-9,10-di-α-methylbenzyloxyanthracene, 9- (α -Methylbenzyloxy) -10-methylanthracene, 9,10-di (2-hydro) Ciethoxy) anthracene, anthracene derivatives such as 2-ethyl-9,10-di (2-carboxyethoxy) anthracene, 1,4-dimethoxychrysene, 1,4-diethoxychrysene, 1,4-dipropoxychrysene, 1, Examples include chrysene derivatives such as 4-dibenzyloxychrysene and 1,4-di-α-methylbenzyloxychrysene, and phenanthrene derivatives such as 9-hydroxyphenanthrene, 9,10-dimethoxyphenanthrene, and 9,10-diethoxyphenanthrene. .

  Among these derivatives, 9,10-dialkoxyanthracene derivatives which may have an alkyl group having 1 to 4 carbon atoms as a substituent are particularly preferable, and the alkoxy group is preferably a methoxy group or an ethoxy group.

  Examples of the carbazole derivative include the following compounds. N-methylcarbazole, N-ethylcarbazole, N-propylcarbazole, N-butylcarbazole, N-vinylcarbazole, 1,3,6,8,9-pentamethylcarbazole, 1,4,5,8,9-penta Methylcarbazole (hereinafter referred to as “NMPC”), 3-formyl-N-ethylcarbazole, N-phenylcarbazole, N-ethyl-3,6-bis (benzoyl) -carbazole (hereinafter referred to as “NEBC”), 9,9′-diethyl-3,3′-dicarbazole (hereinafter referred to as “NEDC”).

  Examples of the phenothiazine derivatives include 2-methoxyphenothiazine, 2-chlorophenothiazine, 2-cyanophenothiazine, 2-acetylphenothiazine, 2-trifluoromethylphenothiazine, 2-methylthiophenothiazine, 2-dimethylaminosulfanylphenothiazine, and the like. .

  Examples of the thioxanthone derivative include thioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone 2-chlorothioxanthone, and the like.

[Surfactant]
Examples of the surfactant that can be used in the cationic polymerizable composition of the present invention include anionic surfactants such as sodium dodecylbenzene sulfonate, sodium lauryl sulfate, sodium dodecyl diphenyl ether disulfonate, sodium dialkyl ester sulfonate succinate and the like. Agents, nonionic surfactants such as polyoxyethylene alkyl esters and polyoxyethylene alkyl aryl ethers, or alkylbetaine type salts such as lauryl betaine and stearyl betaine salts, lauryl-β-alanine, lauryl di (aminoethyl) glycine And both amino acid type surfactants such as octyldi (aminoethyl) glycine.

  Moreover, in the cationically polymerizable composition of the present invention, for example, a silicon-based surfactant, a fluorine-based surfactant, an acetylene-based surfactant, or the like can be used.

  The silicon surfactant is preferably a dimethylpolysiloxane whose side chain or terminal is polyether-modified (polyether-modified polysiloxane compound). For example, KF-351A and KF-642 manufactured by Shin-Etsu Chemical Co., Ltd. and Big Chemie BYK347, BYK348 and the like.

  In addition, the fluorine-based surfactant means a compound in which a part or all of the surfactant is substituted with fluorine in place of hydrogen bonded to carbon of a hydrophobic group of a normal surfactant. Of these, those having a perfluoroalkyl group in the molecule are preferred.

  Some of the fluorosurfactants are commercially available, for example, under the trade name Megafac F from Dainippon Ink Chemical Co., Ltd. and under the trade name Surflon from Asahi Glass Co., Ltd. EI Dupont Nemeras and Company, Inc. under the trade name Fluorad FC from Minnesota Mining and Manufacturing Company, and Monfloor from Imperial Chemical Industry Are sold under the trade name Zonyls, and under the trade name Licobet VPF from Farbeberke Hoechst.

  Examples of nonionic fluorosurfactants include Megafax 144D manufactured by Dainippon Ink and Surflon S-141 and 145 manufactured by Asahi Glass Co., and amphoteric fluorosurfactants. Examples of the agent include Surflon S-131 and 132 manufactured by Asahi Glass Co., Ltd.

  The acetylene surfactant that can be used in the present invention is an acetylene glycol surfactant, which has a triple bond in the molecule, a hydroxyl group and an alkyl group on the adjacent carbon atom, and In other words, a symmetrical structure is preferable. The acetylene glycol compound and acetylene alcohol compound that can be used in the present invention can be obtained as commercially available products, such as Surfynol, Orphine manufactured by Nissin Chemical Industry Co., Ltd., and acetylenol manufactured by Kawaken Fine Chemical Co., Ltd. It is done.

<Image forming method>
Next, an image forming method using the actinic ray curable inkjet ink of the present invention will be described.

  In the image forming method of the present invention, a method is preferred in which the actinic radiation curable inkjet ink of the present invention is ejected and drawn on a recording material by an inkjet recording method, and then the ink is cured by irradiation with an actinic ray such as ultraviolet rays.

(Total ink film thickness after ink landing)
In the present invention, the total ink film thickness after the ink has landed on the recording material and cured by irradiation with actinic rays is preferably 2 to 20 μm. In the actinic ray curable inkjet recording in the screen printing field, the total ink film thickness currently exceeds 20 μm, but in the flexible packaging printing field where the recording material is often a thin plastic material, the recording material described above is used. In addition to the problem of curling and wrinkles, there is a problem in that the entire printed material is changed in its strain and texture.

  Here, the “total ink film thickness” means the maximum value of the film thickness of the ink drawn on the recording material, and it is a single color or other two-color overlay (secondary color), three-color overlay, four colors Even when recording is performed by the overlapping (white ink base) inkjet recording method, the meaning of the total ink film thickness is the same.

(Ink ejection conditions)
When forming an image using the ink of the present invention, it is preferable from the viewpoint of ejection stability that the recording head and the ink are heated to 35 to 100 ° C. and ejected as the ink ejection conditions.

  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.

(Light irradiation conditions after ink landing)
In the image forming method of the present invention, the actinic ray is preferably irradiated for 0.001 second to 1.0 second after the ink landing, more preferably 0.001 second to 0. .5 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 head unit, and the 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 of the head unit and irradiating the recording unit with UV light is disclosed. Yes. Any of these irradiation methods can be used in the image forming method of the present invention.

(Inkjet recording device)
An ink jet recording apparatus (hereinafter simply referred to as a recording apparatus) applicable to the image forming method of the present invention will be described.

  Hereinafter, a recording apparatus applicable to the present invention will be described with reference to the drawings as appropriate. Note that the recording apparatus shown in the figure is merely an example of a recording apparatus that can be applied to the present invention, and the recording apparatus is not limited to this drawing.

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

  The recording 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 recording material 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 recording material 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 white (W), yellow (Y), magenta (M), cyan (C), black (K), light yellow (Ly), light magenta (Lm), and light cyan (Lc). Although the drawing is carried out assuming that the recording heads 3 of light black (Lk) and white (W) are accommodated, the number of colors of the recording heads 3 accommodated in the head carriage 2 is determined as appropriate. Is.

  The recording head 3 is operated by an operation of an ejection unit (not shown) provided with a plurality of actinic ray curable inkjet inks (for example, ultraviolet curable ink) supplied by an ink supply unit (not shown). The ink is discharged from the discharge port toward the recording material P. The ultraviolet curable ink ejected by the recording head 3 is composed of a coloring material, a polymerizable monomer, an initiator, and the like. Upon receiving the ultraviolet irradiation, the photopolymerization initiator and the hindered phenol compound serve as a catalyst. It has the property of being cured by crosslinking and polymerization reaction of the monomer accompanying the action.

  During the scanning in which the recording head 3 moves from one end of the recording material P to the other end of the recording material P in the Y direction in FIG. 1 by driving the head scanning means, a certain area (landing possible area) in the recording material P On the other hand, actinic ray curable inkjet ink is ejected as ink droplets, and the ink droplets are landed on the landable area.

  The above-described scanning is performed as many times as necessary, and after the ultraviolet curable ink is discharged toward one landable area, the recording material P is appropriately moved from the front to the back in FIG. While performing scanning according to the above, the recording head 3 discharges the ultraviolet curable ink to the landing possible area adjacent to the back in FIG.

  By repeating the above-described operation and discharging the ultraviolet curable ink from the recording head 3 in conjunction with the head scanning means and the conveying means, an image composed of an aggregate of ultraviolet curable ink droplets is formed on the recording material P. .

  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, a conventionally known ultraviolet irradiation lamp can be exemplified, and in particular, a low-pressure mercury lamp having a low irradiation energy, an LED (light emitting diode), and the like are applicable.

  The irradiation means 4 is the largest one that can be set by the recording apparatus (ultraviolet curable ink jet printer) 1 among the landable areas in which the recording head 3 ejects the ultraviolet curable ink by one scan driven by the head scanning means. The shape is almost the same or larger than the landable area.

  The irradiation means 4 is fixed on both sides of the head carriage 2 so as to be substantially parallel to the recording material P.

  As described above, as a means for adjusting the illuminance of the ink discharge portion, not only the entire recording head 3 is shielded, but in addition, the ink discharge of the recording head 3 is determined from the distance h1 between the irradiation means 4 and the recording material P. It is effective to increase the distance h2 between the portion 31 and the recording material P (h1 <h2), or to increase the distance d between the recording head 3 and the irradiation means 4 (d is increased). Further, it is more preferable that a bellows structure 7 is provided between the recording head 3 and the irradiation means 4.

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

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Preparation of pigment dispersion >>
The pigment was dispersed with the following composition.

PB824 (manufactured by Ajinomoto Fine Techno Co., Ltd., polymer dispersant) 9 parts by mass OXT-221 (Oxetane compound, manufactured by Toagosei Co., Ltd.) 71 parts by mass The above two compounds are put in a stainless beaker and heated at 65 ° C. Heating, stirring and dissolving for 1 hour while heating above.

  Next, after cooling to room temperature, C.I. I. 20 parts by weight of Pigment Blue 15: 4 (manufactured by Dainichi Seika Co., Ltd., Chromofine Blue 6332JC) was placed in a glass bottle together with 200 g of zirconia beads having a diameter of 0.5 mm, and dispersed with a paint shaker for 9 hours. The zirconia beads were removed to obtain a cyan pigment dispersion.

<Preparation of ink>
[Preparation of Ink 1]
Ink 1 was prepared by sequentially adding, stirring, and dissolving the following common additives and specific additives, followed by filtration through a Teflon (registered trademark) 3 μm membrane filter manufactured by ADVATEC.

<Common additives>
Cyan pigment (solid content of cyan pigment in cyan pigment dispersion) 3.0% by mass
Dispersant: Solid content of dispersant in PB824 cyan pigment dispersion) 1.0% by mass
Oxetane compound: OXT221 (manufactured by Toagosei Co., Ltd., bifunctional, di [1-ethyl (3-oxetanyl)] methyl ether, including OXT221 amount in cyan pigment dispersion)
54.0% by mass
Oxetane compound: OXT101 (manufactured by Toagosei, monofunctional, 3-ethyl-3-hydroxymethyloxetane) 3.0% by mass
Oxetane compound: OXT212 (manufactured by Toagosei, monofunctional, 3-ethyl-3- (2-ethylhexyloxymethyl)) 7.0% by mass
Epoxy compound: Celoxide 2021P (manufactured by Daicel Chemical Industries, Ltd., bifunctional alicyclic epoxy compound) 23.7% by mass
Epoxy compound: Vikoflex 7010 (manufactured by ATOFINA, epoxidized soybean oil (epoxidized fatty acid glyceride)) 5.0 mass%
Basic compound: Tributylamine 1.0% by mass
Surfactant: KF-351, silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1% by mass
Ion exchange water 1.0% by mass
<Specific additives>
Photopolymerization initiator: CPI-100P: 50% propylene carbonate solution of triallylsulfonium salt, 1.2% by mass manufactured by San Apro
Antioxidant: Hindered phenol compound not added [Preparation of inks 2-39]
In the preparation of the ink 1, the addition amount of the photopolymerization initiator (CPI-100P), which is the specific additive, and the kind and addition amount of the hindered phenol compound were respectively changed as shown in Table 1, and were the same. Thus, inks 2 to 39 were prepared. In addition, the addition amount of OXT221 which is an oxetane compound was adjusted suitably so that the total amount might be 100 mass% with the addition amount change of a specific additive.

<Recording images>
A serial type ink jet recording apparatus having the structure shown in FIG. 1 having a piezo-type recording head is loaded with the ink shown in Table 1 to a PVC (polyvinyl chloride) film having a width of 600 mm, a length of 20 m, and a thickness of 100 μm. The liquid was discharged under the following conditions. The ink supply system was composed of an ink tank, a supply pipe, a front chamber ink tank immediately 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 head is heated in accordance with the viscosity of each ink, and is driven so that it can be ejected at a resolution of 720 × 720 dpi (dpi represents the number of dots per 2.54). Continuous discharge was performed, and a solid image was printed. The recording material was adjusted to 40 ° C. with a surface heater and a cooling device. After landing, an active energy ray was irradiated from the following LED light source and cured instantaneously (less than 0.5 seconds after landing). The ink discharge amount was printed with a minimum droplet amount of 4 pl and a maximum appropriate liquid amount of 80 pl. Further, the inkjet image was formed at a temperature of 23 ° C. and a humidity of 30%.

LED light source: LEDZero 395 (manufactured by INTEGRATION, peak wavelength: 395 nm, illuminance: 1 to 2.5 W / cm ² )
<< Evaluation of ink and formed image >>
[Outgoing stability]
After each ink was ejected continuously for 30 minutes from the ink jet recording apparatus, the state of ink shortage was visually observed, and the emission stability was evaluated according to the following criteria.

○: Ink missing is observed with nozzles of less than 0.5%, but good level Δ: Ink missing is recognized with nozzles of 0.5% or more and less than 2.0%, but is acceptable for image formation Quality x: Insufficient ink level with nozzles of 2.0% or more, unacceptable level [Evaluation of curability]
About each formed image, the image printing surface immediately after actinic ray irradiation was touched with the finger | toe, and sclerosis | hardenability was evaluated according to the following reference | standard.

A: The surface of the formed image has no stickiness and is completely cured. ○: The surface of the formed image has no stickiness and is sufficiently cured. Δ: A slightly sticky feeling is recognized on the surface of the formed image. However, the surface of the formed image has a sticky feeling and the curing is insufficient. XX: The formed image does not cure and flows. [Evaluation of weather resistance]
Each formed image was irradiated with a xenon lamp (50 W / m ² ) at 60 ° C. and 55% RH for 8 hours using a low-temperature xenon fade meter XL75 manufactured by Suga Test Instruments Co., Ltd., and then irradiated with light. However, it was allowed to rain for 5 minutes in the cabinet, and then the lamp was turned off and left in an environment of 50 ° C. and 95% RH for 4 hours. This total processing was defined as one cycle, and the density variation rate with respect to the unprocessed solid image was determined for images processed continuously for 168 cycles (2030 hours), and the weather resistance was evaluated according to the following criteria.

A: Image density reduction rate is 3% or less B: Image density reduction rate is 4% or more, 8% or less Δ: Image density reduction rate is 9% or more, 15% or less X: Image density reduction rate Is 16% or more and 25% or less. XX: Image density reduction rate is 26% or more Table 1 shows the results obtained.

  As is apparent from the results shown in Table 1, the ink of the present invention containing the photopolymerization initiator and the hindered phenol compound at the ratio specified in the present invention is more stable than the comparative example. It can be seen that the film has excellent properties and the formed image has excellent curability and weather resistance.

Example 2
<Preparation of ink>
In the preparation of inks 1 to 39 described in Example 1, inks 40 to 40 were prepared in the same manner except that the photopolymerization initiator was replaced with CPI-100P and Example Compound S-5 was used as shown in Table 2. 78 was prepared.

《Image recording and evaluation》
In the same manner as in the method described in Example 1, image recording and ink and formed image were evaluated, and the results obtained are shown in Table 2.

  As is apparent from the results shown in Table 2, the ink of the present invention containing the photopolymerization initiator and the hindered phenol compound at the ratio specified in the present invention is more stable than the comparative example. It can be seen that the film has excellent properties and the formed image has excellent curability and weather resistance.

Example 3
In Example 1, the active energy ray irradiation light source was replaced with the LED, and the same evaluation was performed using a low-pressure mercury lamp and a fluorescent lamp. As a result, the same effects as those shown in Table 1 were confirmed.

DESCRIPTION OF SYMBOLS 1 Recording apparatus 2 Head carriage 3 Recording head 31 Ink ejection port 4 Irradiation means 5 Platen part 6 Guide member 7 Bellows structure 8 Irradiation light source P Recording material

Claims (8)

  In the cationically polymerizable composition containing the cationic polymerizable monomer and the photopolymerization initiator (A), the hindered phenol compound (B) is contained, and the content of the photopolymerization initiator (A) is 1 with respect to the total mass. The mass ratio (A / B) of the photopolymerization initiator (A) to the hindered phenol compound (B) is 1.0 mass% or more and 2.5 mass% or less. A cationically polymerizable composition, which is 0 or less. The cationic polymerized composition according to claim 1, wherein the hindered phenol compound is a compound represented by the following general formula (1).

Wherein, R ¹ represents an alkyl group. R ² represents a hydrogen atom, an alkyl group or an acylamino group. R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a substituent that can be substituted on the benzene ring. ]   Content of this hindered phenol type compound (B) is 1.05 mass% or more and 2.0 mass% or less, The cationically polymerizable composition of Claim 1 or 2 characterized by the above-mentioned.   4. The cationically polymerizable composition according to claim 1, wherein the content of the photopolymerization initiator (A) is 2.0% by mass or more and 2.5% by mass or less. object.   The mass ratio (A / B) of the photopolymerization initiator (A) and the hindered phenol compound (B) is 2.0 or more and 4.0 or less, any one of claims 1 to 4 The cationically polymerizable composition according to claim 1.   The cationically polymerizable composition according to any one of claims 1 to 5, further comprising a pigment as a coloring material.   An actinic ray curable inkjet ink, which comprises the cationic polymerizable composition according to any one of claims 1 to 6, wherein the actinic ray curable inkjet ink is cured by irradiation with actinic rays.   The actinic ray curable inkjet ink according to claim 7 is ejected onto a recording medium by an inkjet recording method, and then the actinic ray is irradiated to the ejected actinic ray curable inkjet ink to form a cured image. An image forming method.

Images