JP2012219203A - White inkjet ink composition and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active energy ray-curable white inkjet ink composition which can allow a cured film formed therefrom to be restrained from being deteriorated or yellowed with time even after preserved as an ink over a long period of time and which is excellent in discharge stability and to provide an inkjet recording method by using the active energy ray-curable white inkjet ink composition.SOLUTION: The active energy ray-curable white inkjet ink composition contains a titanium oxide pigment as a white pigment, and a polymerizable compound. Rutile-type titanium dioxide accounts for ≥50 mass% of the titanium oxide pigment and the white inkjet ink composition further contains a hindered amine compound having a piperidine structure.

Description

  The present invention relates to a novel active energy ray-curable white ink composition for inkjet and an inkjet recording method using the same.

  Known inkjet inks include water-based inkjet inks, solvent-based inkjet inks, and active energy ray-curable inkjet inks. The active energy ray-curable ink-jet ink containing no solvent is characterized by its quick-drying property because it does not require drying of water or an organic solvent during ink-jet recording. Also, it has the characteristic that the formed image is relatively close to the substrate without the ink absorbing layer, and it is used mainly in the field of printing on rigid substrates such as hard plastics, metals and ceramics. It has been put into practical use.

  In recent years, in sign and display applications, in addition to color inks such as yellow, magenta, cyan, and black, white can be expressed on various substrates such as transparent substrates, color substrates, and metal substrates. Ink (white ink) is used. White ink not only expresses white on a substrate other than white, but also improves the color development of the color ink printed on it by printing a white solid image as the base of the color ink. Also have.

  Examples of the color material for white ink include inorganic white pigments such as barium sulfate, calcium carbonate, titanium oxide, and zinc oxide, or organic white pigments such as hollow polymer fine particles. From the viewpoint of whiteness, concealment, and cost. Titanium oxide pigments are commonly used. For example, a cationic polymerization type ultraviolet curable ink-jet ink using a white pigment such as titanium oxide is disclosed (for example, see Patent Document 1). The active energy ray curable inkjet ink forms a cured film by polymerizing a polymerizable compound in the ink with active energy rays. The formed cured film gradually deteriorates due to ultraviolet rays, heat, moisture, oxygen in the air and air pollutants, and cracks, choking (the surface becomes powdery), discoloration, and peeling from the substrate occur. To do. The active energy ray-curable white ink containing a titanium oxide pigment is inferior in weather resistance to that of a normal color material, and particularly choking occurs remarkably. It is considered that the titanium oxide used as the white pigment also functions as a photocatalyst, and the generated active oxygen or OH radical decomposes the cured film component (resin component). Titanium oxide used as a white pigment uses a rutile type with a low activity compared to an anatase type with a high photochemical activity, and further suppresses the activity by coating the surface with alumina or silica, but with an ink with a high pigment concentration, The suppression effect was insufficient.

  As a technique for preventing deterioration of the polymer over time, a method of adding a stabilizer (antioxidant) is known. However, general phenolic antioxidants have the problem of yellowing over time due to coexistence with titanium oxide. In particular, white ink is problematic because yellowing is more visually noticeable than color ink. In addition, when an image was formed using a white ink stored for a long time, the weather resistance of the formed cured film was insufficient.

  On the other hand, a photocurable inkjet ink composition containing at least a photoradical polymerization initiator, a compound having a functional group containing active hydrogen, and a hindered amine compound is disclosed (for example, see Patent Document 2). It is described that the hindered amine compound is effective in improving the storage stability of the ink because it functions as a polymerization inhibitor in the radical polymerization type ultraviolet curable inkjet ink. However, in the examples described in Patent Document 2, anatase-type titanium dioxide is used as a white pigment, and there is no suggestion regarding the weather resistance of the formed cured film.

JP 2004-59627 A JP 2009-132864 A

  The present invention has been made in view of the above problems, and its purpose is to have an activity that can suppress deterioration with time and yellowing of a formed cured film even after being stored as an ink for a long period of time, and has excellent emission stability. An object of the present invention is to provide an energy ray curable white ink composition for inkjet and an inkjet recording method using the same.

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

  1. In the active energy ray-curable inkjet white ink composition containing a titanium oxide pigment and a polymerizable compound as a white pigment, 50% by mass or more of the titanium oxide pigment is rutile titanium dioxide, and has a piperidine structure. A white ink composition for inkjet, comprising a hindered amine-based compound.

  2. 2. The white ink composition for inkjet according to 1, wherein the hindered amine compound has a piperidine structure that is not a free radical.

  3. 3. The white ink composition for inkjet according to 1 or 2, wherein the hindered amine compound has a piperidine structure in which a nitrogen atom is substituted with a substituted or unsubstituted alkoxy group.

  4). 4. The hindered amine compound according to any one of 1 to 3, wherein the hindered amine compound has a substituent at the 4-position of the piperidine structure, and the substituent includes an ester group, an ether group, or an amino group. White ink composition for inkjet.

  5). 5. The white ink composition for inkjet according to any one of items 1 to 4, further comprising an ultraviolet absorber.

  6). 6. The white ink composition for inkjet according to 5, wherein the ultraviolet absorber is a triazine compound.

  7). 7. The white ink composition for inkjet according to any one of 1 to 6, wherein a sodium ion concentration is 200 ppm or less.

  8). 8. The inkjet white ink composition according to any one of 1 to 7 above is applied onto a substrate, and an image is formed by irradiating the inkjet white ink composition with active energy rays. Inkjet recording method.

  9. At least on an image formed by applying the white ink composition for inkjet according to any one of 1 to 7 on a substrate and irradiating the white ink composition for inkjet with active energy rays, An inkjet recording method, further comprising applying an inkjet color ink composition containing a colorant and a polymerizable compound.

  According to the present invention, an active energy ray-curable white ink composition for inkjet which can suppress deterioration with time and yellowing of a formed cured film even after being stored as an ink for a long period of time and has excellent emission stability, and An ink jet recording method using the can be provided.

It is a front view which shows an example of a structure of the principal part of the inkjet recording device used for the inkjet recording method of this invention. It is a top view which shows another example of a structure of the principal part of the inkjet recording device used for the inkjet recording method of this 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 has found that an active energy ray-curable ink-jet white ink composition containing a titanium oxide pigment and a polymerizable compound as a white pigment, 50% by mass or more of rutile-type titanium dioxide and a hindered amine compound having a piperidine structure containing a hindered amine compound, a cured film formed even after being stored as an ink for a long period of time As a result, it has been found that an active energy ray-curable white ink composition for inkjet that can suppress deterioration with time and yellowing of the ink and has excellent emission stability can be realized.

  That is, the hindered amine compound having a piperidine structure exists stably for a long time even in an ink containing a polymerizable compound in combination with a rutile-type titanium dioxide pigment, and is affected by ultraviolet rays, heat, moisture, oxygen, etc. after forming a cured film. Therefore, even if active oxygen or OH radicals are generated from the titanium oxide pigment, it is considered that these can be continuously trapped to prevent deterioration of the cured film. In particular, by adding a hindered amine compound that is not a free radical, it can exist more stably in the ink, and after forming a cured film, it exhibits a radical trap function for a longer period of time, and the effect of the present invention is more remarkable. It is thought that.

<White ink composition for inkjet>
Hereinafter, the details of the white ink composition for inkjet according to the present invention will be described.

  The ink-jet white ink composition of the present invention (hereinafter also referred to as white ink or white ink) comprises 50% by mass or more of a titanium oxide pigment containing rutile titanium dioxide, a polymerizable compound, and a hindered amine having a piperidine structure. A system compound is contained.

[White pigment]
The white ink of the present invention contains a titanium oxide pigment as a white pigment, and is characterized in that 50% by mass or more of the titanium oxide pigment is rutile type titanium dioxide, and preferably 80% by mass or more of the titanium oxide pigment. Is the configuration of rutile titanium dioxide. The titanium oxide pigment applicable to the present invention is preferably surface-treated with alumina, silica, zinc, zirconia, organic matter or the like.

  The surface-treated titanium oxide pigment may contain sodium ions, and in the white ink of the present invention, the sodium ion concentration in the white ink is preferably adjusted to 200 ppm or less, more preferably 50 ppm or less containing 0 ppm. is there.

  In the present invention, as a means for adjusting the sodium ion concentration in the white ink to the range specified above, a method of reducing the amount of sodium salt used for the surface treatment, a method of washing the titanium oxide pigment by a known method, or the like. Can be mentioned.

  As an average particle diameter of the titanium oxide pigment which concerns on this invention, it is preferable that it is 50-500 nm, and it is more preferable that it is 100-300 nm. By adjusting the average particle size of the titanium oxide pigment to the range specified above, the effect of the present invention is remarkably exhibited, and the nozzle clogging in the inkjet head is suppressed, and the storage stability of the white ink composition for inkjet ( In particular, it is preferable in that the suppression of sedimentation) and the concealability with respect to the printed substrate can be sufficiently exhibited.

  The titanium oxide pigment applicable to the present invention can also be obtained as a commercial product, for example, CR-50, CR-57, CR-58, CR-67, CR-Super- manufactured by Ishihara Sangyo Co., Ltd. 70, CR-80, CR-90, CR-90-2, CR-93, CR-95, CR-EL, R-550, R-580, R-630, R-670, R-680, R- 780, R-820, R-830, R-850, R-930, R-980, PF-736, PF-737, PF-742, SR-41, R-5N, R- manufactured by Sakai Chemical Industry Co., Ltd. 7E, R-11P, R-21, R-25, R-32, R-42, R-44, R-45M, R-62N, R-310, R-650, TCR-52, GTR-100, D-918, FTR-700, etc. are mentioned.

  The addition amount of titanium oxide in the white ink of the present invention is preferably in the range of 5.0% by mass to 35% by mass with respect to the total mass of the ink, and more preferably in the range of 10% by mass to 20% by mass. By adjusting the addition amount of titanium oxide in the white ink of the present invention to the range specified above, it is effective in achieving both storage stability (particularly, suppression of sedimentation) of the white ink composition for inkjet and shielding properties against the print substrate. Can be expressed.

  A known white pigment other than the titanium oxide according to the present invention may be used in combination with the white ink of the present invention as necessary. Examples of other white pigments applicable to the present invention include inorganic white pigments, organic white pigments, and white hollow polymer fine particles.

  Examples of inorganic white pigments include alkaline earth metal sulfates such as barium sulfate, alkaline earth metal carbonates such as calcium carbonate, silicas such as finely divided silicic acid and synthetic silicates, calcium silicate, alumina, alumina Hydrates, zinc oxide, talc, clay and the like can be mentioned.

  Examples of the organic white pigment include organic compound salts disclosed in JP-A No. 11-129613 and alkylene bismelamine derivatives disclosed in JP-A Nos. 11-14365 and 2001-234093.

  Specific examples of commercially available white pigments include Shigenox OWP, Shigenox OWPL, Shigenox FWP, Shigenox FWG, Shigenox UL, and Shigenox U (all trade names manufactured by Hackol Chemical Co., Ltd.).

  Examples of the white hollow polymer fine particles include fine particles showing thermoplasticity substantially made of an organic polymer disclosed in US Pat. No. 4,089,800. White pigments may be used alone or in combination.

  Moreover, in order to adjust the color tone of the white ink composition for inkjet according to the present invention, a small amount of other colored material (for example, dye, pigment, etc.) can be added as required.

  For the dispersion of the white pigment according to the present invention, 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 white pigment. As the dispersant, a polymer dispersant is preferably used. Examples of the polymer dispersant include Avecia's Solsperse series and Ajinomoto Fine-Techno's PB series. Furthermore, the following are mentioned.

  Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a salt of a long chain polyaminoamide and a polar acid ester, a high molecular weight unsaturated acid ester, Polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl Examples thereof include phenyl ether, stearylamine acetate, and pigment derivatives.

  Specific examples include “Anti-Terra-U (polyaminoamide phosphate)”, “Anti-Terra-203 / 204 (high molecular weight polycarboxylate)” manufactured by BYK Chemie, “Disperbyk-101 (polyaminoamide phosphate). And acid ester), 107 (hydroxyl group-containing carboxylic acid ester), 110 (copolymer containing an acid group), 130 (polyamide), 161, 162, 163, 164, 165, 166, 170 (polymer copolymer) ”,“ 400 ”,“ Bykumen ”(high molecular weight unsaturated acid ester),“ BYK-P104, P105 (high molecular weight unsaturated acid polycarboxylic acid) ”,“ P104S, 240S (high molecular weight unsaturated acid polycarboxylic acid and Silicone ”),“ Lactimon (long chain amine, unsaturated acid polycarboxylic acid and Corn) "and the like.

  Also, “Efka CHEMICALS” “Efka 44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71, 701, 764, 766”, “Efka Polymer 100 (modified polyacrylate), 150 (aliphatic) System modified polymer), 400, 401, 402, 403, 450, 451, 452, 453 (modified polyacrylate), 745 (copper phthalocyanine system) "; Kyoei Chemical Co., Ltd." Floren TG-710 (urethane oligomer) "," “Flonon SH-290, SP-1000”, “Polyflow No. 50E, No. 300 (acrylic copolymer)”; “Disparon KS-860, 873SN, 874 (polymer dispersing agent), # 2150, manufactured by Enomoto Kasei Co., Ltd. (Aliphatic polyvalent carboxylic acid), # 7004 (polyether ester type) " It is.

  Furthermore, “Demol RN, N (Naphthalenesulfonic acid formalin condensate sodium salt), MS, C, SN-B (aromatic sulfonic acid formalin condensate sodium salt), EP”, “Homogenol L-18 (made by Kao Co., Ltd.) Polycarboxylic acid type polymer) "," Emulgen 920, 930, 931, 935, 950, 985 (polyoxyethylene nonylphenyl ether) "," acetamine 24 (coconut amine acetate), 86 (stearyl amine acetate) "; "Solspers 5000 (phthalocyanine ammonium salt type), 13240, 13940 (polyesteramine type), 17000 (fatty acid amine type), 24000, 32000" manufactured by Nikko Chemical Co., Ltd. "Nikkor T106 (polyoxyethylene sorbitan monooleate), MY" -IEX (polyoxyethylene monostearate), Hexagline4-0 (hexaglyceryl ruthenate Huwei rate) ", and the like.

  These pigment dispersants are preferably contained in the white ink in the range of 0.1 to 20% by mass. Moreover, it is also possible to use a synergist according to various white 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 white pigment. The dispersion medium is used using a solvent or a polymerizable compound. However, the white ink of the present invention is preferably solvent-free because it is reacted and cured after printing. 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, particularly a monomer having a low viscosity.

[Hindered amine compounds]
The ink-jet white ink composition of the invention contains a hindered amine compound having a piperidine structure.

  Furthermore, the hindered amine compound preferably has a piperidine structure that is not a free radical. The piperidine structure that is not a free radical in the present invention means that the nitrogen atom contained in piperidine and the atom directly bonded to the nitrogen atom do not adopt a radical structure.

  In the present invention, the hindered amine compound according to the present invention preferably has a tertiary amine piperidine structure. Furthermore, it is a preferable embodiment that the hindered amine compound has a piperidine structure in which a nitrogen atom is substituted with a substituted or unsubstituted alkoxy group.

  The hindered amine compound having a piperidine structure according to the present invention is not particularly limited, but is preferably a compound having a piperidine structure represented by the following general formula (1).

In the general formula (1), Z represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, or O. (oxygen atom radical). R ₁ and R ₁₀ each represent an alkyl group having 1 to 4 carbon atoms, R ₂ and R ₉ each represent a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, and R _{3 to} R ₈ each represent a hydrogen atom. Or represents a substituent.

  In the above general formula (1), Z is preferably an optionally substituted alkyl group or alkoxy group, and particularly preferably the N substituent is a substituted or unsubstituted alkoxy group. The alkyl group and alkoxy group represented by Z each include a cyclic structure.

In the general formula _(1), the R _{1, R 10} are each an alkyl group having 1 to 4 carbon _atoms, R 2, _{R 9} are each a hydrogen atom, it represents an alkyl group having 1 to 4 carbon atoms, _{R 1} , R ₂ , R ₉ and R ₁₀ are preferably methyl groups.

  The hindered amine compound according to the present invention preferably has a substituent at the 4-position of the piperidine structure, and the substituent has an ester group, an ether group or an amino group. Specific examples include compounds represented by the following general formula (2) to general formula (5).

Wherein, R ₁₁ represents an alkyl group, a cycloalkyl group or an alkenyl group having 1 to 30 carbon atoms, Z has the same definition as Z in the general formula (1).

_{Wherein, R 12} represents a divalent linking group having 1 to 30 carbon atoms, Z has the same definition as Z in the general formula (1).

In the formula, each of R _{31 to} R ₃₄ represents an alkyl group having 1 to 30 carbon atoms, a cycloalkyl group, an alkenyl group, or a group represented by the following general formula (6), and at least one of R _{31 to} R ₃₄ Is a group represented by the general formula (6).

  Z is synonymous with Z in the general formula (1).

In the formula, R ₄₁ represents a substituent having the partial structure of the general formula (6). R ₄₂ and R ₄₃ represent a hydrogen atom or a substituent, and the substituent may include a partial structure of the general formula (6).

  Specific examples of the compound represented by the general formula (1) include the following compounds.

  Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, poly {[6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4 -Diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]}, tetrakis (2,2 , 6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, 2,2,6,6-tetramethyl-4-piperidinylbenzoate, (mixed 2,2 , 6,6-tetramethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, mixed {2,2,6,6-tetramethyl-4-piperidyl / β, β, β ', β'-tetramethyl -3-9- [2,4,8,10-tetraoxaspiro (5.5) undecane] diethyl} -1,2,3,4-butanetetracarboxylate, poly {[6-N-morpholyl-1] , 3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) ) Imino]}, [N- (2,2,6,6-tetramethyl-4-piperidyl) -2-methyl-2- (2,2,6,6-tetramethyl-4-piperidyl) imino] propion Amides etc.

  In addition, hindered amine compounds having a piperidine structure are commercially available, for example, LA-77, LA-57, LA-67 manufactured by ADEKA, or TINUVIN 111 FDL, TINUVIN 123, TINUVIN 144, TINUVIN manufactured by BASF Japan. 152, TINUVIN 292, TINUVIN 765, TINUVIN 770 DF, and the like.

  Below, an example of the structure of the hindered amine-type compound which has the typical piperidine structure marketed is shown.

  The addition amount of the compound represented by the general formula (1) is preferably 0.1% by mass or more and 4.0% by mass or less with respect to the total mass of the white ink of the present invention. When the content is 0.1% by mass or more, the weather resistance improvement effect is large, and when the content is 4.0% by mass or less, practical curability can be obtained. Especially preferably, it is 0.2 mass% or more and 3.0 mass% or less.

(Polymerizable compound)
The white ink of the present invention is characterized by containing a polymerizable compound having a property of being cured by irradiation with active energy rays together with a titanium oxide pigment and a hindered amine compound having a piperidine structure.

  Hereinafter, the photopolymerizable compound that is cured by active energy rays applicable to the present invention will be described.

  Examples of the active energy ray in the present invention include electron beam, ultraviolet ray, α ray, γ ray, X ray, etc., but the danger to the human body and easy handling are widespread in industrial use. UV light or electron beam is preferred. In the present invention, it is particularly preferable to use ultraviolet rays.

  In the present invention, the photopolymerizable compound that is crosslinked or polymerized by irradiation with active energy rays can be used without particular limitation, and among them, it is preferable to use a cationic polymerizable compound or a radical polymerizable compound.

(Cationically polymerizable compound)
As the cationic polymerizable monomer applicable to 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 Epoxy compounds, vinyl ether compounds, oxetane compounds and the like exemplified in each of the above publications.

  In the present invention, at the time of curing the white ink, the photopolymerizable compound is selected from at least one oxetane compound, an epoxy compound, and a vinyl ether compound for the purpose of suppressing shrinkage of the substrate (hereinafter also referred to as a substrate). It is preferable to contain at least one compound.

<Epoxy compound>
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 thereof. Examples thereof include di- or polyglycidyl ethers of oxide 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.

  As the alicyclic epoxide, cyclohexene oxide or cyclopentene obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with an appropriate oxidizing agent such as hydrogen peroxide or peracid. 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. In the present invention, one of the epoxides may be used alone, or two or more may be used in appropriate combination.

<Vinyl ether compound>
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.

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

  The compound having an oxetane ring used in the present invention is preferably a compound having 1 to 4 oxetane rings from the viewpoints of the viscosity of the ink composition, the flexibility of the cured composition, and the adhesion to the substrate.

  Examples of the compound having an oxetane ring that can be preferably used in the present invention include compounds represented by general formula (1) described in paragraph No. (0089) of JP-A-2005-255821, and the same publication. The general formula (2), the general formula (7) of the paragraph number (0107), the general formula (8) of the paragraph number (0109), and the general formula of the paragraph number (0166) described in the paragraph number (0092) of The compound represented by (9) etc. can be mentioned.

  Specific examples thereof include the exemplified compounds 1 to 6 described in paragraph numbers (0104) to (0119) and the compounds described in paragraph number (0121) of the publication.

(Radically polymerizable compound)
Next, the radical polymerizable compound will be described.

  The radical polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, and may be any compound as long as it has at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. , Oligomers, polymers and the like having a chemical form. Only one kind of radically polymerizable compound may be used, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve desired properties.

  Examples of compounds having an ethylenically unsaturated bond capable of radical polymerization include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid and their salts, esters, urethanes, amides. And radically polymerizable compounds such as various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides and unsaturated urethanes.

  Examples of the radically polymerizable compound applicable to the present invention include all known (meth) acrylate monomers and / or oligomers. The term “and / or” as used in the present invention means that it may be a monomer, an oligomer, or both. The same applies to the items described below.

  As the compound having a (meth) acrylate group, for example, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate 2-acryloyloxyethyl hexahydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2- Hydroxyethyl acrylic 2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl-phthalate Monofunctional monomers such as acid, lactone-modified flexible acrylate, t-butylcyclohexyl acrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1, 4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, Bifunctional monomers such as methylol-tricyclodecane diacrylate, PO adduct diacrylate of bisphenol A, neopentyl glycol diacrylate hydroxypivalate, polytetramethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, penta Trifunctional or more polyfunctional such as erythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxytriacrylate, caprolactone-modified trimethylolpropane triacrylate, pentaerythritol ethoxytetraacrylate, caprolactam-modified dipentaerythritol hexaacrylate Monomer. In addition, polymerizable oligomers can be blended in the same manner as the monomer. Examples of the polymerizable oligomer include epoxy acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, polyester acrylate, and linear acrylic oligomer. More specifically, Yamashita Shinzo, “Cross-linking agent handbook” (1981 Taiseisha); Kato Kiyosumi, “UV / EB curing handbook (raw material)” (185, Polymer publication society); Study Group, “Application and Market of UV / EB Curing Technology”, page 79 (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun) Commercially available products or radically polymerizable or crosslinkable monomer oligomers and polymers known in the industry can be used.

  Among the above monomers, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomyristyl acrylate are particularly preferred from the viewpoints of sensitization, skin irritation, eye irritation, mutagenicity, toxicity, etc. , Isostearyl acrylate, ethoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, isobornyl acrylate, lactone-modified flexible acrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, dipentaerythritol Hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin Po carboxymethyl triacrylate, caprolactone modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, caprolactam modified dipentaerythritol hexaacrylate preferred.

  Furthermore, among these, stearyl acrylate, lauryl acrylate, isostearyl acrylate, ethoxydiethylene glycol acrylate, isobornyl acrylate, tetraethylene glycol diacrylate, glycerin propoxy triacrylate, cowprolactone-modified trimethylolpropane triacrylate, caprolactam-modified dipenta Erythritol hexaacrylate is particularly preferred.

  The amount of the radical polymerizable compound added is preferably 1.0 to 97% by mass, more preferably 30 to 95% by mass based on the total mass of the white ink.

  In addition, a polymerizable compound (for example, maleimide derivative) having an electron accepting group and a polymer having an electron donating group described in Japanese Patent Nos. 3353020, 11-124403, and 2003-213171. A charge transfer complex polymerization compound used in combination with an organic compound (for example, vinyl ether derivative) may be used.

  Examples of the polymerizable compound having an electron accepting group include vinylene dicarboxylic anhydride, vinylene imide compound, vinylene dicarboxylic acid, vinylene dicarboxylic acid ester, vinylene monocarboxylic acid amide monocarboxylic acid, vinylene monocarboxylic acid amide monocarboxylic acid ester, Vinylene dicarboxylic acid amide, vinylene nitrile compound substituted with nitrile group at both ends of vinylene skeleton, vinyl halide compound substituted with halogen group at both ends of vinylene skeleton, vinylene ketone compound substituted with carbonyl at both ends of vinylene skeleton, vinylene dithiocarboxylic acid anhydride , Vinylene thioimide compound, vinylene dithiocarboxylic acid, vinylene dithiocarboxylic acid ester, vinylene monothiocarboxylic acid amide monothiocarboxylic acid, vinylene monothiocarboxylic acid amide mono Okarubon esters, vinyl range thio carboxylic acid amide, compounds pyridyl group which is substituted vinylene backbone ends, but such compounds structure pyrimidyl group is substituted on vinylene skeleton ends include, but are not limited to. Among these, vinylene dicarboxylic acid anhydride, vinylene imide such as maleimide and citraconic imide, vinylene dicarboxylic acid such as maleic acid and fumaric acid, vinylene dicarboxylic acid ester such as maleic acid ester and fumaric acid ester and the like are preferable. .

  Examples of the polymerizable compound having an electron donor group include alkenyl ethers such as vinyl ether and propenyl ether, alkenyl thioethers such as vinyl thioether and propenyl thioether, alkenyl sulfoxides such as vinyl sulfoxide and propenyl sulfoxide, and oxygen atoms of carboxylic acid esters. Vinyl esters with a vinyl group bonded to them, vinylamines with a vinyl group bonded to the nitrogen atom of the amino group, vinylamides with a vinyl group bonded to the nitrogen atom of the amide group, vinyl with a vinyl group bonded to the nitrogen atom of the imidazole ring Examples thereof include imidazole, vinyl carbazole in which a vinyl group is bonded to a nitrogen atom of a carbazole ring, a cyclic 5-membered ring containing a vinylene skeleton and an oxygen atom in the ring, and a cyclic 6-membered ring compound.

  Specific examples of the vinyl ether include compounds listed as vinyl ether compounds described in the cationic polymerizable compound.

[Photopolymerization initiator group]
Examples of the additive constituting the photopolymerization initiator group according to the present invention include radical polymerization initiators, cationic polymerization initiators, initiation assistants, and sensitizers. The amount of these photopolymerization initiators added to the ink is preferably 0.5 to 10 parts by mass of the total ink.

  Various known compounds can be used for the photopolymerization initiator group according to the present invention, and the photopolymerization initiator group is selected from those soluble in the polymerizable compound.

(Photopolymerization initiator)
<Radical polymerization initiator>
As the radical photopolymerization initiator applicable to the ink composition of the present invention, those of molecular cleavage type or hydrogen abstraction type are suitable for the present invention. Specific examples include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzyl, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1- (4-morpholino Phenyl) -butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and the like are preferably used. Further, other molecular cleavage types include 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4- Isopropyl fe ) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 1- [4- (2-hydroxyethoxy)- Phenyl] -2-hydroxy-2-methyl-1-propan-1-one or the like may be used in combination, and hydrogen abstraction type photopolymerization initiators such as benzophenone, 4-phenylbenzophenone, isophthalphenone, 4- Benzoyl-4'-methyl-diphenyl sulfide, a metallocene type polymerization initiator bis (2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) ) -Phenyl) titanium, an oxime ester type polymerization initiator, 1,2-octanedione, 1- (4- (phenylthio) -, 2- (O-benzoyloxime)), ethanone, 1- (9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl)-, 1- (O-acetyloxime) and the like Can be used. Further, α-aminoacetophenone compounds, acylphosphine oxide compounds, α-hydroxyacetophenone compounds, oxime ester compounds and the like described in JP-A-2008-208321 can be mentioned.

  In addition, as a sensitizer for the photo radical polymerization initiator, for example, trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, A radical polymerizable compound such as N, N-dimethylbenzylamine and 4,4′-bis (diethylamino) benzophenone can be used in combination with an amine that does not cause an addition reaction.

  These polymerization initiators are preferably contained in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the compound having an ethylenically unsaturated bond capable of radical polymerization.

<Cationic polymerization initiator>
The photocurable ink according to the present invention preferably contains a cationic polymerization initiator as a photopolymerization initiator together with the cationic polymerizable compound.

  Specific examples of the cationic polymerization initiator include a photoacid generator and the like. For example, a chemical amplification type photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “ Organic materials for imaging ", Bunshin Publishing (1993), see pages 187-192). 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.

  Specific examples of the onium compound that can be used in the present invention include compounds described in paragraph No. (0132) of JP-A No. 2005-255821.

  Second, specific examples of the sulfonated compound that generates sulfonic acid include compounds described in paragraph No. (0136) of JP-A No. 2005-255821.

  Thirdly, a halide that generates hydrogen halide can also be used, and specific examples thereof include the compounds described in paragraph No. (0138) of JP-A No. 2005-255821. it can.

  Fourthly, an iron allene complex described in paragraph No. (0140) of JP-A-2005-255821 can be mentioned.

(Sensitizer)
In the white ink of the present invention, a sensitizer having ultraviolet spectrum absorption at a wavelength longer than 300 nm can be used. For example, at least one hydroxyl group, optionally substituted aralkyloxy group or alkoxy group can be substituted. Polycyclic aromatic compounds, carbazole derivatives, thioxanthone derivatives, and the like.

  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.

  Examples of these sensitizers that can be used in the present invention include carbazole derivatives, naphthalene derivatives such as condensates of naphthol derivatives and formalin, anthracene derivatives, chrysene derivatives, phenanthrene derivatives, and the like. 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 methoxy group and ethoxy group are preferable as the alkoxy group.

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

(Starting aid)
An initiator is a substance that acts as a sensitizing dye that improves the radical or acid generation efficiency of an initiator by donating energy to the initiator by light irradiation, electron donation, electron attraction, heat generation, etc. Yes, applied in combination with initiator.

  Examples of the initiation assistant include xanthene, thioxanthone dye, ketocoumarin, thioxanthene dye, 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, pyrylium compound, pyromethene compound, pyrazolotriazole compound, benzothiazole compound, barbituric acid derivative, thiobarbituric acid derivative and the like can be applied.

  In addition to the above-mentioned compounds, it is well known that the initiator acts as a sensitizing dye in documents such as “Development technology of polymer additives” (CMC Publishing Co., Ltd., supervised by Junichi Daikatsu). The substance may be applied. The initiation assistant can also be regarded as a component that forms part of the photopolymerization initiator.

  Examples of a combination of a radical polymerization initiator and an initiator aid applied to a radical polymerizable compound include a peracid ester that is a radical polymerization initiator and xanthene, thioxanthone dye, ketocoumarin, and thiopyrylium salt as initiator initiators. Combinations and combinations of onium salts such as diphenyliodonium salts that are cationic polymerization initiators and thioxanthene dyes that are initiation assistants are well known.

[Ultraviolet absorber]
The white ink of the present invention preferably contains an ultraviolet absorber in addition to the structure defined in the present invention, and more preferably, the ultraviolet absorber is a triazine compound.

  As the ultraviolet absorber applicable to the present invention, conventionally known compounds can be used. For example, inorganic ultraviolet absorbers such as cerium oxide described in JP-A-9-157560, JP-A-9-279075, JP-A-2001-181528, JP-A-46-2784, JP-A-5 Benzophenone ultraviolet absorbers, salicylic acid ester ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, JP-A-58-185777, JP-A-61-190537, JP-A-2-19483, etc. Benzotriazole-based ultraviolet absorbers described in JP-A No. 782, JP-A-5-97075, JP-A-9-34057, etc., JP-A-4-298503, JP-A-8-53427, and JP-A-8-239368. Triazine UV absorption described in JP-A-10-182621, JP-A-8-501291, etc. Organic UV absorbers and the like.

<Inorganic UV absorber>
The inorganic ultraviolet absorber according to the present invention is mainly a metal oxide pigment, and is a compound having a function of reducing the light transmittance in the UV-B region (290-320 nm) region to 10% or less. Examples of inorganic ultraviolet absorbers applicable to the present invention include zinc oxide, iron oxide, zirconium oxide, cerium oxide, and mixtures thereof.

  Moreover, it is preferable that the inorganic ultraviolet absorber which concerns on this invention is an inorganic ultraviolet absorber fine particle whose surface-coated average particle diameter is 10 nm or more and 100 nm or less. Surface-coated inorganic ultraviolet absorbers as used herein include amino acids, beeswax, fatty acids, fatty alcohols, anionic surfactants, lecithin, fatty acid sodium salts, potassium salts, zinc salts, iron salts or aluminum salts, metal alkoxides Chemical, electronic, mechanochemical or mechanical, with compounds such as titanium (aluminum), polyethylene, silicone, protein (collagen, elastin), alkanolamine, silicon oxide, metal oxide or sodium hexametaphosphate An inorganic ultraviolet absorber that has undergone a surface treatment by one or more means of special nature.

<Organic UV absorber>
In the white ink of the present invention, it is particularly preferable to use an organic ultraviolet absorber as the ultraviolet absorber.

  Examples of the organic ultraviolet absorber applicable to the present invention include the benzophenone series, benzotriazole series, phenyl salicylate series, and triazine series.

  Examples of benzophenone-based ultraviolet absorbers include 2,4-dihydroxy-benzophenone, 2-hydroxy-4-methoxy-benzophenone, 2-hydroxy-4-n-octoxy-benzophenone, 2-hydroxy-4-dodecyloxy-benzophenone, 2-hydroxy-4-octadecyloxy-benzophenone, 2,2'-dihydroxy-4-methoxy-benzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-benzophenone, 2,2 ', 4,4' -Tetrahydroxy-benzophenone and the like.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5-methylphenyl) benzotriazole and 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole. 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) benzotriazole and the like.

  Examples of the phenyl salicylate ultraviolet absorber include phenylsulcylate, 2-4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, and the like.

  Examples of triazine ultraviolet absorbers include 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy- 4-ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy- 4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- ( 2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5- Riazine, 2,4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-benzyloxyphenyl)- 1,3,5-triazine and the like can be mentioned.

  In the present invention, among the above ultraviolet absorbers, triazine-based ultraviolet absorbers are preferably used. Triazine-based ultraviolet absorbers are commercially available, and examples thereof include TINUVIN 400, TINUVIN 405, TINUVIN 460, TINUVIN 479, and TINUVIN 1577 FF manufactured by BASF Japan.

[Other additives]
In addition to the above description, various additives can be used for the white ink of the present invention as long as the object effects of the present invention are not impaired. 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 addition, any known basic compound can be used for the purpose of improving storage stability. Typical examples include basic organic compounds such as basic alkali metal compounds, basic alkaline earth metal compounds, and amines. Etc.

<Color ink composition for inkjet>
In the ink jet recording method of the present invention, the above-described white ink composition for ink jet (white ink) of the present invention described above is applied onto a substrate, and the white ink composition for ink jet is irradiated with active energy rays to form an image. It is characterized by forming. Furthermore, after forming a white image on a base material, an ink containing a color material is formed by further applying an ink-jet color ink composition containing at least a color material and a polymerizable compound on the white image. This is preferable because it has an effect on the weather resistance of an image formed by the above method.

  The basic structure of the ink-jet color ink composition (hereinafter also referred to as colored ink) according to the present invention is the same as the above-described ink-jet white ink composition (white ink) of the present invention and the type of color material used. Except for this, almost the same configuration can be adopted.

[Color material]
As the coloring material, colored pigments and dyes such as yellow, magenta, cyan, and black can be used, but pigments that have good dispersion stability with respect to colored ink components and excellent weather resistance can be used. preferable.

(Pigment)
Although it does not necessarily limit as a pigment, For example, the organic or inorganic pigment of the following number described in a color index can be used for this invention.

Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, and 53: 1. 57: 1, 57: 2, 58: 4, 63: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 88, 104, 108, 112, 122, 123, 144, 146 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13 16, 20, 36,
As the blue or cyan pigment, Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17-1, 22, 27, 28, 29, 36, 60 ,
Examples of green pigments include Pigment Green 7, 26, 36, 50,
As the yellow pigment, Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138 139, 150, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193,
As the black pigment, Pigment Black 7, 28, 26 and the like can be used according to the purpose.

  Specific product names include, for example, chromo fine yellow 2080, 5900, 5930, AF-1300, 2700L, chromo fine orange 3700L, 6730, chromo fine scarlet 6750, chromo fine magenta 6880, 6886, 6891N, 6790, 6887. , Chromofine Violet RE, Chromofine Red 6820, 6830, Chromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, Chromofine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Black Fine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400 (B), 2500, 2600, ZAY-260, 2700 (B), 2770, Seika Fast Red 8040, C405 (F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmine 6B1476T-7, 1383LT, 3840, 3870, Seika Fast Bordeaux 10B-430, Seika Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C7 8, A612, cyanine blue 4933M, 4933GN-EP, 4940, 4973 (manufactured by Dainichi Seika Kogyo), KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301, 302 , 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (large Nippon Ink Chemical Co., Ltd.), Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pi ment Yellow 1705, Colortex Orange 202, Colortex Red 101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C USN, Colortex Maroon 601, Colortex Brown B610N, Colortex violet 600, Pigment Red 122, Colortex Blue 516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403B, Col. , Lionol B lue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink), Toner Magenta E02, Permanent RubinF6B, Toner Yellow HG, Permanent Yellow GG-02, HosteBem G2 , Hostaperm Pink E, Hostaperm Blue B2G (manufactured by Clariant), carbon black # 2600, # 2400, # 2350, # 2200, # 1000, # 990, # 980, # 970, # 960, # 950, # 850, MCF88, # 750, # 650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77, # 52, # 50, # 47, # 45, # 45L, # 40, # 33, # 32, # 30, # 25, # 20, # 10, # 5, # 44, CF9 (Mitsubishi Chemical) Can be mentioned.

  With respect to the dispersion method of each pigment or the applicable dispersant, the method and the dispersant used in the preparation of the white pigment in the above-described white ink of the present invention can be similarly applied.

(dye)
In the colored ink according to the present invention, a conventionally known dye, preferably an oil-soluble dye can be used. Specific examples of oil-soluble dyes that can be used in the present invention are given below, but the present invention is not limited to these.

<Magenta dye>
MS Magenta VP, MS Magenta HM-1450, MS Magenta HSo-147 (manufactured by Mitsui Toatsu Co., Ltd.), AIZENSOT Red-1, AIZEN SOT Red-2, AIZEN SOTRed-3, AIZEN SOT Pink-1, SPERON Red GE SPECIAL (above, manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN Red FB 200%, MACROLEX Red Violet R, MACROLEX ROT5B (above, manufactured by Bayer Japan), KAYASET Red B, KAYASET Red 130, KAYASET Red Japan 802 ), PHLOXIN, ROSE BENGAL, ACID Red (above, made by Daiwa Kasei), HSR-31, DIARESIN Red K (below) , Manufactured by Mitsubishi Kasei Co., Ltd.), Oil Red (manufactured by BASF Japan Co., Ltd.).

<Cyan dye>
MS Cyan HM-1238, MS Cyan HSo-16, Cyan HSo-144, MS Cyan VPG (manufactured by Mitsui Toatsu Co., Ltd.), AIZEN SOT Blue-4 (manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN BR. Blue BGLN 200%, MACROLEX Blue RR, CERES Blue GN, SIRIUS SUPRATURQ. Blue Z-BGL, SIRIUS SUTRA TURQ. Blue FB-LL 330% (above, Bayer Japan), KAYASET Blue FR, KAYASET Blue N, KAYASET Blue 814, Turq. Blue GL-5 200, Light Blue BGL-5 200 (above, Nippon Kayaku Co., Ltd.), DAIWA Blue 7000, Oleosol Fast Blue GL (above, Daiwa Kasei), DIARESIN Blue P (Mitsubishi Kasei), SUDAN Blue 670, NEOPEN Blue 808, ZAPON Blue 806 (above, manufactured by BASF Japan).

<Yellow dye>
MS Yellow HSm-41, Yellow KX-7, Yellow EX-27 (Mitsui Toatsu), AIZEN SOT Yellow-1, AIZEN SOT YellowW-3, AIZEN SOT Yellow-6 (above, manufactured by Hodogaya Chemical Co., Ltd.), MACROLEX Yellow 6G, MACROLEX FLUOR. Yellow 10GN (above, manufactured by Bayer Japan), KAYASET Yellow SF-G, KAYASET Yellow 2G, KAYASET Yellow AG, KAYASET Yellow EG (above, manufactured by Nippon Kayaku), DAIWA YELLOW 330H HSY-68 (manufactured by Mitsubishi Kasei Co., Ltd.), SUDAN Yellow 146, NEOPEN Yellow 075 (above, manufactured by BASF Japan).

<Black dye>
MS Black VPC (Mitsui Toatsu Co., Ltd.), AIZEN SOT Black-1, AIZEN SOT Black-5 (above, Hodogaya Chemical Co., Ltd.), RESORIN Black GSN 200%, RESOLIN Black BS (above, Bayer Japan Co., Ltd.), KAYASET Black A-N (manufactured by Nippon Kayaku Co., Ltd.), DAIWA Black MSC (manufactured by Daiwa Kasei Co., Ltd.), HSB-202 (manufactured by Mitsubishi Kasei Co., Ltd.), NEPTUNE Black X60, NEOPEN Black X58 (manufactured by BASF Japan) .

  The addition amount of the pigment or oil-soluble dye is preferably 0.1 to 20% by mass, more preferably 0.4 to 10% by mass, based on the total mass of the colored ink. If it is 0.1% by mass or more, good image quality can be obtained, and if it is 20% by mass or less, an appropriate ink viscosity in ink ejection can be obtained. Also, two or more kinds of color materials can be mixed and used in a timely manner for color adjustment.

"Base material"
The substrate applicable to the ink jet recording method of the present invention is not particularly limited. In addition to a substrate having a high ink absorbing ability such as plain paper, coated paper, ink jet exclusive paper, and fabric, the ink absorbing ability is low or Examples of the non-absorbing base material that does not have ink absorbing ability include the non-absorbing base material that has a low ink absorbing ability or has no ink absorbing ability in the inkjet recording method of the present invention. It is more effective when it is a substrate.

  These non-absorbing substrates are substrates whose surfaces are composed of resin components, specifically, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride, acrylic resin, polyolefin, A resin plate such as polycarbonate, vinyl chloride, polyethylene terephthalate (PET), plastic film, synthetic paper, or a material in which these plastic films are pasted on a base material such as paper. It is a substrate. Substrates and coated papers whose surface is composed of a resin component have poor ink absorbability, and the surface energy of the substrate is low. Therefore, ink is not absorbed even when printing with water-based inkjet ink, and the ink is not The image is distorted, the drying property is poor, and the adhesiveness of the ink is low, so the image durability is poor, but by applying the inkjet recording method of the present invention, even these substrates, An image excellent in image uniformity, white spot resistance and abrasion resistance can be obtained. Furthermore, it can be applied to a base material such as metal or ceramic.

<Inkjet recording method>
The ink jet recording method of the present invention is characterized in that an image is formed by applying the white ink composition for ink jet of the present invention onto a substrate and irradiating the white ink composition for ink jet with active energy rays. Furthermore, at least a colorant and a polymerizable compound are formed on an image formed by applying the white ink composition for inkjet of the present invention onto a substrate and irradiating the white ink composition for inkjet with active energy rays. It is preferable to further provide an inkjet color ink composition containing

  Hereinafter, the ink jet recording method of the present invention will be described.

  In the ink jet recording method of the present invention, an ink jet head used for forming an image by discharging the white ink composition for ink jet of the present invention or the color ink composition for ink jet of the present invention onto a substrate is on-demand. Either the method or the continuous method may be used. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, thermal ink jet) Any ejection method such as a mold, a bubble jet (registered trademark) mold, or the like may be used.

(White ink and colored ink ejection conditions)
As a discharge condition of the white ink of the present invention and the colored ink according to the present invention (hereinafter also simply referred to as “each ink”), the recording head and each ink are heated to 35 to 100 ° C. and discharged. This is preferable in terms of ejection stability. Each ink composition has a large viscosity fluctuation range due to temperature fluctuations, and the viscosity fluctuation greatly affects the ink droplet size and ink droplet ejection speed to fly, causing image quality degradation. Must be kept constant. The control range of each ink temperature is set temperature ± 5 ° C., preferably set temperature ± 2 ° C., and more preferably set temperature ± 1 ° C.

(Light irradiation conditions after landing on each ink substrate)
In the ink jet recording method of the present invention, as the irradiation condition of the active energy ray, it is preferable that the active energy ray is irradiated for 0.001 to 2.0 seconds after each ink has landed on the substrate. More preferably, it is 0.001 to 1.0 seconds. In order to form a high-definition image, it is particularly important to make the irradiation timing as early as possible.

  As a method for irradiating active energy rays, a basic method is disclosed in Japanese Patent Application Laid-Open No. 60-132767. According to this, the active energy ray irradiation light source is provided on both sides of the head unit, and the recording head and the active energy ray irradiation light source are scanned by the shuttle method. Irradiation is performed after a certain period of time after each ink has landed on the substrate. Furthermore, the curing can be 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 irradiating an image forming unit with ultraviolet light by applying a collimated light source to a mirror surface provided on the side of the head unit is disclosed. Has been. Any of these irradiation methods can be used in the inkjet recording method of the present invention.

  Also, the irradiation of active energy rays is divided into two stages. As the first stage, after each ink has landed on the substrate, the active energy rays are irradiated by the above-described method for 0.001 to 2.0 seconds. As a second stage, a method of further irradiating active energy rays after the completion of all printing is also one of preferred embodiments. By dividing the irradiation of active energy rays into two stages, it becomes possible to suppress the shrinkage of the base material that occurs during ink curing.

  Conventionally, in the UV inkjet method, a light source with high illuminance in which the total power consumption of the light source exceeds 1 kW · hr is usually used to suppress dot spread and bleeding after the ink has landed on the substrate. It was. However, when these light sources are used, particularly in printing on a shrink label or the like, the shrinkage of the substrate is so large that it cannot be practically used.

  In the present invention, even when a light source with an hourly power consumption of 1 kW or less is used, a high-definition image can be formed, and the shrinkage of the substrate can be kept within a practically acceptable level. Examples of light sources that consume less than 1 kW per hour include, but are not limited to, fluorescent tubes, cold cathode tubes, LEDs, and the like.

(Total ink film thickness after ink landing)
In the inkjet recording method of the present invention, the total ink film thickness after each ink has landed on the substrate and cured by irradiation with active energy rays is 2 to 20 μm. This is preferable in terms of changes in material texture.

  The “total ink film thickness” here means the maximum value of the film thickness of the ink drawn on the base material, and even for a single color, other two color layers (secondary colors), three color layers, Even when recording is performed using a four-color overlapping (white ink base) inkjet recording method, the meaning of the total ink film thickness is the same.

(Ink ejection conditions)
The amount of ink droplets ejected from the nozzles is preferably 2 to 50 pl from the viewpoint of recording speed and image quality. In the case of white ink, since solid printing is mainly used, a discharge amount larger than that of color ink expressing gradation is preferable.

(Inkjet recording device)
Next, an ink jet recording apparatus (hereinafter simply referred to as a recording apparatus) that can be used in the ink jet recording method of the present invention will be described with reference to the drawings as appropriate.

  FIG. 1 is a front view showing a configuration of a main part of the ink jet recording apparatus.

  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 white (W), yellow (Y), magenta (M), cyan (C), black (K), light yellow (Ly), light magenta (Lm), and light cyan (Lc). ), Light black (Lk), and white (W) are drawn as being housed. However, the number of colors of the print head 3 housed in the head carriage 2 is appropriately determined in the implementation. It is what In the recording head, the white ink of the present invention is ejected from white (W). The recording head 3 discharges each ink supplied by an 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. .

  In the ink jet recording method of the present invention, as a first step, the recording head 3 is moved from one end of the substrate P to the other end of the substrate P in the Y direction in FIG. In the meantime, white ink is ejected as ink droplets from white (W), which is the recording head, to a certain region (landable region) on the substrate P, and the ink droplets are landed on the landable region. Next, the white ink droplets landed on the substrate are cured by irradiating with active energy rays from the irradiation means 4.

  The irradiation unit 4 includes, for example, 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 mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a hot cathode tube, a germicidal lamp, a black light, an LED (light emitting diode) and the like can be applied, and a strip-shaped metal halide is applicable. Lamps, cold cathode tubes, germicidal lamps, mercury lamps or LEDs are preferred. In particular, the LED has a small size, a long lifetime, high efficiency, and low cost, and is expected as a light source for photo-curable ink jet. It is preferable to use an LED having a peak wavelength at 350 to 420 nm.

  The irradiating means 4 has substantially the same shape as the maximum one that can be set by the recording apparatus (UV inkjet printer) 1 among the landable areas in which the recording head 3 ejects each ink by one scan driven by the head scanning means. , Having 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.

  As described above, as 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 substrate P. It is effective to increase the distance h2 between the portion 31 and the substrate 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.

  Next, as a second stage of the ink jet recording method of the present invention, after white ink is ejected on the substrate and cured, scanning is performed as appropriate in the same manner as above, toward one landable area, Color inks from yellow (Y), magenta (M), cyan (C), black (K), light yellow (Ly), light magenta (Lm), light cyan (Lc), and light black (Lk) recording heads Is discharged. In the case of a transparent substrate, the color ink may be ejected first and cured, and then the white ink may be ejected. The above operation is repeated, and each color ink is ejected from the recording head 3 in conjunction with the head scanning means and the conveying means, and then the active energy rays are irradiated from the irradiation means 4 in the same manner as described above, whereby the substrate P is irradiated. A desired image is formed.

  Each recording head can be arranged so as to be shifted with respect to the conveyance direction of the base material P (the direction from the front to the back in FIG. 1) depending on the color (so-called staggered arrangement). In particular, by disposing the white (W) recording head with respect to the conveyance direction of the recording heads of the other colors and the base material P, the white ink and the color ink are transferred to the base material P by one scan of the head carriage 2. The color ink can be landed efficiently on the image formed with the white ink.

  FIG. 2 is a top view illustrating another example of the configuration of the main part of the ink jet recording apparatus.

  The ink jet recording apparatus shown in FIG. 2 is called a line head system, and a plurality of ink jet recording heads 3 of each color are fixedly arranged on the head carriage 2 so as to cover the entire width of the substrate P. ing.

  On the other hand, on the downstream side of the head carriage 2, that is, the rear portion of the head carriage 2 in the direction in which the base material P is conveyed, the entire width of the base material P is also covered so as to cover the entire ink printing surface. Arranged irradiation means 4 are provided.

  As the ultraviolet lamp used in the illuminating means 4, the same one as described in FIG. 1 can be used.

  In this line head system, the head carriage 2 and the irradiation unit 4 are fixed, and only the base material P is transported, and ink ejection and curing are performed to form an image.

  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 white pigment dispersion>
[Preparation of white pigment dispersion 1]
After mixing each of the following additives, a white pigment dispersion 1 having a titanium oxide content of 25% by mass was dispersed using a sand grinder manufactured by Imex Co., which was filled with 50% by volume of 0.5 mm zirconia beads. Was prepared.

Titanium oxide pigment 1: rutile type titanium dioxide, average particle diameter: 250 nm, TiO ₂ content: 95% by mass, TiO ₂ particle surface treated with Al ₂ O ₃ 25 parts by mass Pigment dispersant: PB824 (Azisper PB824, polymer pigment Dispersant, manufactured by Ajinomoto Fine Techno Co., Ltd.) 5.0 parts by mass Dispersion medium: OX221 (Oxetane 221, di [1-ethyl (3-oxetanyl)] methyl ether, manufactured by Toagosei Co., Ltd.) 70 parts by mass [White pigment dispersion 2 Preparation of ~ 6]
In preparing the white pigment dispersion 1, white pigment dispersions 2 to 6 were prepared in the same manner except that the type of titanium oxide pigment and the type of dispersion medium were changed to the combinations shown in Table 1.

  In addition, the detail of each additive described with the abbreviation in Table 1 is as follows.

<Titanium oxide pigment>
Rutile type: rutile type titanium dioxide, average particle size: 250 nm, TiO ₂ content: 95% by mass, TiO ₂ particle surface treated with Al ₂ O ₃ anatase type: anatase type titanium dioxide, average particle size: 160 nm, TiO ₂ particles Surface treated with Al ₂ O ₃ <Pigment dispersant>
PB824: Azisper PB824, polymer pigment dispersant, manufactured by Ajinomoto Fine-Techno Co., Ltd. <Dispersion medium>
OX221: oxetane 221, di [1-ethyl (3-oxetanyl)] methyl ether, manufactured by Toagosei Co., Ltd. TEGDVE: triethylene glycol divinyl ether TeEGDA = tetraethylene glycol diacrylate << Preparation of white ink >>
[Preparation of white ink 1-1]
While stirring 48.0 parts of the prepared white pigment dispersion 1 (rutile titanium dioxide), the following additives were sequentially added to prepare a white ink having a total amount of 100 parts. Subsequently, it filtered with a 0.8 micrometer filter, and prepared the cationic polymerizable white ink 1-1 whose ratio of a rutile type titanium dioxide with respect to the titanium oxide pigment total mass is 100 mass%. The sodium ion content in the white ink 1-1 was 50 ppm or less.

White pigment dispersion 1 (rutile-type titanium dioxide) 48.0 parts by mass Oxetane compound (manufactured by Toagosei Co., Ltd., OXT-221) 14.0 parts by mass 1,2: 8,9 diepoxy limonene 10.0 parts by mass 3, 4-Epoxycyclohexenylmethyl-3 ', 4'-epoxycyclohexenecarboxylate 20.0 parts by weight Propylene carbonate 1.5 parts by weight Photopolymerization initiator: di (4-methoxyphenyl) mono (4-methylphenyl) sulfonium hexa Fluorophosphate 2.5 parts by mass Sensitizer: 9,10-diethoxyanthracene 2.5 parts by mass Additive A: Hindered amine compound, TINUVIN123 (manufactured by BASF Japan, see the above structural formula) 0.5 parts by mass UV Absorbent: TINUVIN479 (manufactured by BASF Japan) 1.0 parts by mass

[Preparation of white ink 1-2]
While stirring 38.4 parts of white pigment dispersion 1 (rutile titanium dioxide) prepared above and 9.6 parts of white pigment dispersion 2 (anatase type titanium dioxide), the following additives were sequentially added. Thus, a white ink having a total amount of 100 parts was prepared. Next, the mixture is filtered through a 0.8 μm filter to obtain a cationic polymerizable white ink 1-2 in which the ratio of rutile titanium dioxide to the total mass of the titanium oxide pigment is 80 mass% and the ratio of anatase titanium dioxide is 20 mass%. Prepared. The sodium ion content in this white ink 1-2 was 50 ppm or less.

White pigment dispersion liquid 1 (rutile type titanium dioxide) 38.4 parts by mass White pigment dispersion liquid 2 (anatase type titanium dioxide) 9.6 parts by mass Oxetane compound (manufactured by Toagosei Co., Ltd., OXT-221) 14.0 parts by mass 1 , 2: 8,9 diepoxy limonene 10.0 parts by weight 3,4-epoxycyclohexenylmethyl-3 ', 4'-epoxycyclohexene carboxylate 20.0 parts by weight propylene carbonate 1.5 parts by weight Photopolymerization initiator: Di (4-methoxyphenyl) mono (4-methylphenyl) sulfonium hexafluorophosphate 2.5 parts by mass Sensitizer: 9,10-diethoxyanthracene 2.5 parts by mass Additive A: Hindered amine compound, TINUVIN 123 (BASF) Made by Japan Co., Ltd. (see previous structural formula) 0.5 parts by weight UV absorber: INUVIN479 (BASF Japan Co., Ltd., see supra structural formula)
1.0 part by mass [Preparation of white ink 1-3 to 1-5]
In the preparation of the white ink 1-2, mass ratios of rutile titanium dioxide and anatase titanium dioxide in the titanium oxide pigment (total amount: 48.0 parts by mass) were 50:50, 40:60, and 30:70, respectively. Cationic polymerizable white inks 1-3 to 1-5 were prepared in the same manner except that the mass ratio was changed.

[Preparation of white ink 1-6 to 1-8]
In the preparation of the above white inks 1-1, 1-3, and 1-5, as additive A, TINUVIN123 (BASF Japan), which is a hindered amine compound, was used in the same amount of TINUVIN152 (BASF Japan, previously mentioned structure). Cationic polymerizable white inks 1-6 to 1-8 were prepared in the same manner except that the formula was changed.

[Preparation of white ink 1-9 to 1-11]
In the preparation of the above white inks 1-1, 1-3, and 1-5, as additive A, TINUVIN123 (BASF Japan), which is a hindered amine compound, was used in the same amount as TINUVIN292 (BASF Japan, previously mentioned structure). Cationic polymerizable white inks 1-9 to 1-11 were prepared in the same manner except that the formula was changed.

[Preparation of white ink 1-12]
In the preparation of the white ink 1-1, a cation polymerizable white was similarly prepared except that TINUVIN123 (BASF Japan), which is a hindered amine compound, was changed to the same amount of the following compound HA-1 as the additive A. Ink 1-12 was prepared.

[Preparation of white ink 1-13]
In the preparation of the above white ink 1-1, except that TINUVIN123 (BASF Japan), which is a hindered amine compound, was changed to the same amount of IRGASTAB UV10 (BASF Japan, * 1) as additive A. Cationic polymerizable white ink 1-13 was prepared.

* 1: IRGASTAB UV10 (a free radical-containing hindered amine compound having a 2,2,6,6-tetramethylpiperidine group)
[Preparation of white ink 1-14]
In the preparation of the white ink 1-1, as the additive A, TINUVIN123 (BASF Japan) which is a hindered amine compound and IRGANOX1076 (BASF Japan, * 2) which is the same amount of hindered phenolic antioxidant are used. A cationically polymerizable white ink 1-14 was prepared in the same manner except that it was changed to.

* 2: IRGANOX 1076 (hindered phenol antioxidant, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate)
[Preparation of white ink 1-15]
Cationic polymerizable white ink 1-15 was prepared in the same manner as in the preparation of white ink 1-1 except that TINUVIN123 (manufactured by BASF Japan), which is a hindered amine compound, was excluded.

[Preparation of white ink 1-16]
While stirring 48.0 parts of the above-prepared white pigment dispersion 3 (rutile titanium dioxide), the following additives were sequentially added to prepare a white ink having a total amount of 100 parts. Subsequently, it filtered with a 0.8 micrometer filter, and prepared the cationic polymerizable white ink 1-16 whose ratio of a rutile type titanium dioxide with respect to the titanium oxide pigment total mass is 100 mass%. The sodium ion content in this white ink 1-16 was 50 ppm or less.

White pigment dispersion 1 (rutile titanium dioxide) 48.0 parts by weight Triethylene glycol divinyl ether 12.5 parts by weight Diethylene glycol divinyl ether 15.0 parts by weight Ethylene oxide-modified trimethylolpropane triacrylate trivinyl ether
10.0 parts by mass Propylene carbonate 3.0 parts by mass Photopolymerization initiator: (4-phenylthiophenyl) diphenylsulfonium hexafluorophosphate 2.5 parts by mass Sensitizer: 9,10-diethoxyanthracene 2.5 parts by mass Hindered amine compound: TINUVIN123 (manufactured by BASF Japan, see the above structural formula) 0.5 part by mass Ultraviolet absorber: TINUVIN479 (manufactured by BASF Japan, see the above structural formula)
1.0 part by mass [Preparation of white ink 1-17]
While stirring 24.0 parts of White Pigment Dispersion Liquid 3 (rutile titanium dioxide) and 24.0 parts of White Pigment Dispersion Liquid 4 (anatase type titanium dioxide), the following additives were sequentially added. Thus, a white ink having a total amount of 100 parts was prepared. Subsequently, the mixture was filtered through a 0.8 μm filter, and a cationic polymerizable white ink 1-17 having a rutile type titanium dioxide ratio of 50% by mass and anatase type titanium dioxide ratio of 50% by mass with respect to the total mass of the titanium oxide pigment was obtained. Prepared. The sodium ion content in this white ink 1-17 was 50 ppm or less.

White pigment dispersion 3 (rutile titanium dioxide) 24.0 parts by weight White pigment dispersion 4 (anatase type titanium dioxide) 24.0 parts by weight Triethylene glycol divinyl ether 12.5 parts by weight Diethylene glycol divinyl ether 15.0 parts by weight Ethylene oxide modified trimethylolpropane triacrylate trivinyl ether
10.0 parts by mass Propylene carbonate 3.0 parts by mass Photopolymerization initiator: (4-phenylthiophenyl) diphenylsulfonium hexafluorophosphate 2.5 parts by mass Sensitizer: 9,10-diethoxyanthracene 2.5 parts by mass Hindered amine compound: TINUVIN123 (manufactured by BASF Japan, see the above structural formula) 0.5 part by mass Ultraviolet absorber: TINUVIN479 (manufactured by BASF Japan, see the above structural formula)
1.0 part by mass [Preparation of white ink 1-18]
In the preparation of white ink 1-17, the mass ratio of rutile titanium dioxide (white pigment dispersion 3) and anatase titanium dioxide (white pigment dispersion 4) in the titanium oxide pigment (total amount: 48.0 parts by mass) In the same manner, except that the ratio was changed to 30:70 (mass ratio), cationically polymerizable white ink 1-18 was prepared.

[Preparation of white ink 1-19]
In preparation of the white ink 1-16, the same except that TINUVIN123 (made by BASF Japan), which is a hindered amine compound, was changed to TINUVIN292 (made by BASF Japan, see the above structural formula) as the additive A in the same manner. Thus, cationically polymerizable white ink 1-19 was prepared.

[Preparation of white ink 1-20]
Cationic polymerizable white ink 1-20 was prepared in the same manner as in the preparation of white ink 1-16 except that TINUVIN123 (manufactured by BASF Japan), which is a hindered amine compound, was excluded.

[Preparation of white ink 1-21]
While stirring 48.0 parts of the above-prepared white pigment dispersion 5 (rutile titanium dioxide), the following additives were sequentially added to prepare a white ink having a total amount of 100 parts. Subsequently, it filtered with a 0.8 micrometer filter, and prepared the radically polymerizable white ink 1-21 whose ratio of a rutile type titanium dioxide with respect to the titanium oxide pigment total mass is 100 mass%. The sodium ion content in this white ink 1-21 was 50 ppm or less.

White pigment dispersion 5 (rutile titanium dioxide) 48.0 parts by mass Tetraethylene glycol diacrylate 13.4 parts by mass ε-caprolactone-modified dipentaerythritol hexaacrylate 5.0 parts by mass Phenoxyethyl methacrylate 25.0 parts by mass Polymerization prohibited Agent: Irganox 1076 (manufactured by BASF Japan) 0.1 parts by mass Photopolymerization initiator: Speedcure TPO (manufactured by LAMBSON) 6.0 parts by mass Sensitizer: Speedcure ITX (manufactured by LAMBSON) 1.0 part by mass Hindered amine compound : TINUVIN123 (manufactured by BASF Japan, see above structural formula) 0.5 parts by mass UV absorber: TINUVIN479 (manufactured by BASF Japan, see above structural formula)
1.0 part by mass [Preparation of white ink 1-22]
While stirring 24.0 parts of White Pigment Dispersion Liquid 5 (rutile titanium dioxide) and 24.0 parts of White Pigment Dispersion Liquid 6 (anatase type titanium dioxide), the following additives were sequentially added. Thus, a white ink having a total amount of 100 parts was prepared. Next, the mixture is filtered through a 0.8 μm filter, and radical polymerizable white ink 1-22 having a rutile type titanium dioxide ratio of 50% by mass and anatase type titanium dioxide ratio of 50% by mass with respect to the total mass of the titanium oxide pigment is obtained. Prepared. The sodium ion content in this white ink 1-22 was 50 ppm or less.

White pigment dispersion 5 (rutile titanium dioxide) 24.0 parts by weight White pigment dispersion 6 (anatase type titanium dioxide) 24.0 parts by weight Tetraethylene glycol diacrylate 13.4 parts by weight ε-caprolactone modified dipentaerythritol hexa Acrylate 5.0 parts by weight Phenoxyethyl methacrylate 25.0 parts by weight Polymerization inhibitor: Irganox 1076 (manufactured by BASF Japan) 0.1 part by weight Photopolymerization initiator: Speedcure TPO (manufactured by LAMBSON) 6.0 parts by weight Sensitizer : Speedcure ITX (manufactured by LAMBSON) 1.0 part by mass Hindered amine compound: TINUVIN123 (manufactured by BASF Japan, see the above structural formula) 0.5 part by mass Ultraviolet absorber: TINUVIN479 (manufactured by BASF Japan, (See previous structural formula)
1.0 part by mass [Preparation of white ink 1-23]
In the preparation of white ink 1-22, the mass ratio of rutile titanium dioxide (white pigment dispersion 5) and anatase titanium dioxide (white pigment dispersion 6) in the titanium oxide pigment (total amount: 48.0 parts by mass) , Radically polymerizable white ink 1-23 was prepared in the same manner except that the ratio was changed to 30:70 (mass ratio).

[Preparation of white ink 1-24]
In the preparation of the above white ink 1-22, the same except that TINUVIN123 (BASF Japan), which is a hindered amine compound, was changed to TINUVIN292 (BASF Japan, see above structural formula) in the same amount as additive A. Thus, radically polymerizable white ink 1-24 was prepared.

[Preparation of white ink 1-25]
Radical polymerizable white ink 1-25 was prepared in the same manner as in the preparation of white ink 1-22, except that TINUVIN123 (manufactured by BASF Japan), which is a hindered amine compound, was excluded.

  In addition, the detail of each additive described by the abbreviation in Table 2 is as follows.

<Additive A>
TI-123: TINUVIN123 (manufactured by BASF Japan)
TI-152: TINUVIN152 (manufactured by BASF Japan)
TI-292: TINUVIN292 (manufactured by BASF Japan)
TI-144: TINUVIN 144 (manufactured by BASF Japan)
UV10: IRGASTAB UV10 (manufactured by BASF Japan)
Irg1076: IRGANOX1076 (manufactured by BASF Japan)
<Evaluation of white ink>
Each of the prepared white inks was evaluated as follows.

[Evaluation of choking resistance]
Each prepared white ink was filled in a light-shielded glass sample bottle and sealed, and then stored at 70 ° C. for 1 week.

Subsequently, the white ink after preservation | save was apply | coated with the wire bar # 3 on the transparent acrylic base material, and it was made to harden | cure by irradiating LED-UV light (main wavelength: 385 nm, irradiation light quantity: 200 mJ / cm < ² >). Next, white solid image obtained by repeating the application and curing of the white ink three times was obtained. This white solid image was subjected to xenon light irradiation (cycle treatment) using a xenon fade meter (test conditions are described below) for a total of 600 hours under various environmental conditions, and then the surface of the taken out white solid image was rubbed with a finger. The degree of powder generation was visually observed, and the choking resistance was evaluated according to the following evaluation rank.

<Irradiation conditions with a xenon fade meter>
Lamp: Xenon arc 52W / cm ² (300-400nm)
Irradiation cycle (1) Light irradiation for 8 hours under high temperature conditions of 60 ° C and 55% RH
(2) Light irradiation for 10 minutes under rain conditions
(3) Light irradiation for 50 minutes under high temperature and high humidity conditions of 50 ° C. and 95% RH For the irradiation cycles (1) to (3), the following combination is defined as one cycle (12 hours), and a total of 600 hours (50 cycles) The cycle process was performed.

1 cycle = (1) + [(2) + (3)] × 4 times = 12 hours <Evaluation rank>
◎: Even if the white solid image surface is rubbed, no white powder adheres to the finger. ○: When the white solid image surface is rubbed, white powder slightly adheres to the finger. White powder adheres x: When the white solid image surface is rubbed, the coating film is peeled off from the acrylic substrate [Evaluation of coloring resistance]
The degree of coloring of the white solid image obtained by the xenon light irradiation produced in the evaluation of the above choking resistance for 600 hours was visually observed, and the coloring resistance was evaluated according to the following criteria.

○: Almost no coloration is observed in the white solid image Δ: Some coloration (especially yellowing) is observed in the white solid image ×: Clear coloring (especially yellowing) is observed in the white solid image [Evaluation of output stability]
Each prepared white ink was sealed in a light-shielded glass sample bottle and stored at 70 ° C. for 1 week. Next, each of the white inks subjected to the storage process was loaded into an inkjet printing apparatus equipped with a drop-on-demand piezo inkjet head (nozzle number: 512, ink droplet amount: 42 pl). Assuming that the light leakage from the UV light source is applied to the nozzle surface of the inkjet head for a long period of time, irradiating the head portion with an illuminance of 0.01 mW / cm ² for 1 hour while irradiating LED-UV light with a wavelength of 385 nm The nozzles were continuously ejected, and the occurrence of nozzle missing or ink ejection bending at each nozzle was visually observed and evaluated according to the following criteria.

◎ No nozzle missing after 1 hour continuous ejection, no bent ink ejection is observed ○: After 1 hour continuous ejection, the number of nozzle missing is within 2 nozzles, and there is no noticeable ink No occurrence of bent emission is observed. Δ: Nozzle missing occurs in 3 to 10 nozzles after continuous emission for 1 hour, and occurrence of bent emission of ink is recognized in a plurality of nozzles. X: Continuous emission is within 30 minutes. Table 2 shows the results obtained as described above, in which nozzle missing of 3 to 10 nozzles was generated and the ink was bent and emitted by a plurality of nozzles.

  As is clear from the results shown in Table 2, it can be seen that the white ink having the configuration defined in the present invention is superior in choking resistance, coloring resistance (yellowing resistance) and emission stability to the comparative example. .

Example 2
<Preparation of white ink>
[Preparation of white inks 2-1 to 2-3]
In the preparation of the white ink 1-1 described in Example 1, in place of TINUVIN479 (manufactured by BASF Japan) which is a hydroxyphenyltriazine-based ultraviolet absorber, the same amount of hydroxyphenyltriazine-based ultraviolet absorber “TINUVIN400 (BASF Japan) White ink 2-1 to 2-3 in the same manner, except that the benzotriazole ultraviolet absorber “TINUVIN384-2” (BASF Japan) and “TINUVIN928” (BASF Japan) were changed. Was prepared.

[Preparation of white ink 2-4]
White ink 2-4 was prepared in the same manner as in the preparation of white ink 1-1 described in Example 1, except that TINUVIN479 (manufactured by BASF Japan), which is a hydroxyphenyltriazine-based ultraviolet absorber, was excluded.

<Evaluation of white ink>
For the white inks 2-1 to 2-4 prepared above and the white ink 1-1 prepared in Example 1, evaluation of choking resistance, coloring resistance and emission stability was performed in the same manner as in Example 1. Table 3 shows the results obtained.

  As is clear from the results shown in Table 3, in the white ink of the present invention, the addition of an ultraviolet absorber, particularly the inclusion of a triazine-based ultraviolet absorber, makes the objective effect of the present invention more prominent. It can be seen that it is expressed.

Example 3
<< Preparation of White Pigment Dispersions 3-1 to 3-5 >>
By appropriately adjusting the cleaning method of the titanium oxide pigment (rutile titanium dioxide, average particle size: 250 nm, TiO ₂ content: 95 mass%, TiO ₂ particle surface treated with Al ₂ O ₃ ), the sodium ion content is 1830 ppm, 1590 ppm, 820 ppm, 390 ppm, and 120 ppm of titanium oxide pigments 3-1 to 3-5 were prepared.

  Next, in the preparation of the white pigment dispersion 1 described in Example 1, the same procedure was performed except that the titanium oxide pigments 3-1 to 3-5 having different sodium ion contents were used instead of the titanium oxide pigment 1. White pigment dispersions 3-1 to 3-5 were prepared.

<< Preparation of white inks 3-1 to 3-5 >>
In the preparation of the white ink 1-1 described in Example 1, in place of the white pigment dispersion 1, the same procedure was used except that the prepared white pigment dispersions 3-1 to 3-5 were used. White inks 3-1 to 3-5 having amounts of 220 ppm, 190 ppm, 98 ppm, 47 ppm, and 14 ppm, respectively, were prepared.

<Evaluation of white ink>
The white inks 3-1 to 3-5 prepared above were evaluated for choking resistance, coloring resistance and emission stability in the same manner as in the method described in Example 1, and the results obtained are shown in Table 4.

  As is clear from the results shown in Table 4, it can be seen that the objective effect of the present invention is more remarkably exhibited in the white ink of the present invention in which the sodium ion content in the ink is 200 ppm or less.

Example 4
<< Color ink composition for inkjet: Preparation of yellow ink >>
[Preparation of Yellow Pigment Dispersion 1]
Each of the following additives was mixed, and then dispersed using a sand grinder manufactured by Imex Co., which was filled with 0.5% zirconia beads at a volume ratio of 50% to prepare Yellow Pigment Dispersion Liquid 1.

Pigment: C.I. I. Pigment Yellow 150 20.0 parts by mass Dispersant: Addisper PB824 (Ajinomoto Fine Techno Co., Ltd.) 7.0 parts by mass Dispersion medium: Oxetane compound (OXT-221 manufactured by Toagosei Co., Ltd.) 73.0 parts by mass [Preparation of Yellow Ink 1] ]
A cationically polymerizable yellow ink 1 having the following composition was prepared.

Yellow Pigment Dispersion 1 17.5 parts by weight Oxetane compound (OXT-221 manufactured by Toagosei Co., Ltd.) 46.0 parts by weight 1,2: 8,9 diepoxy limonene 10.0 parts by weight 3,4-epoxycyclo 1. Hexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate 20.0 parts by weight Propylene carbonate 1.5 parts by weight Photopolymerization initiator: di (4-methoxyphenyl) mono (4-methylphenyl) sulfonium hexafluorophosphate 5 parts by mass Sensitizer: 9,10-diethoxyanthracene 2.5 parts by mass << Evaluation Method >>
The white ink 1-1 (invention) and the white ink 1-15 (comparative example) prepared in Example 1 were each filled in a light-shielded glass sample bottle and sealed, and the sample bottle was then sealed at 70 ° C. Stored for 1 week.

Into an inkjet printing apparatus equipped with a drop-on-demand piezo inkjet head (nozzle number: 512, ink droplet amount: 42 pl), the stored white ink 1-1, 1-15 and the yellow ink 1 prepared above were used. Loaded. Next, a solid image was formed by applying each white ink to a transparent acrylic substrate, and cured with LED-UV light (main wavelength: 385 nm, irradiation light amount: 200 mJ / cm ² ) to form a white solid image. After that, yellow ink 1 was applied on the white solid image to form a yellow solid image, and then cured with LED-UV light (same as above) to produce laminated solid images 1 and 2.

  After irradiating xenon light for 600 hours using a xenon fade meter (irradiation conditions are the same as the evaluation conditions described in Example 1) on each of the stacked solid images obtained by laminating the yellow image on the white image formed as described above. The choking resistance of the surface of the laminated solid image taken out was evaluated according to the same criteria as in the method described in Example 1, and the obtained results are shown in Table 5.

  As is clear from the results shown in Table 5, a laminated solid image formed by applying a polymerizable yellow ink containing a yellow color material on a white image formed with a white ink having a configuration defined in the present invention. Also, it can be seen that an effect excellent in choking resistance after image storage is exhibited.

DESCRIPTION OF SYMBOLS 1 Recording device 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 Base material

Claims (9)

  In the active energy ray-curable inkjet white ink composition containing a titanium oxide pigment and a polymerizable compound as a white pigment, 50% by mass or more of the titanium oxide pigment is rutile titanium dioxide, and has a piperidine structure. A white ink composition for inkjet, comprising a hindered amine-based compound.   The white ink composition for inkjet according to claim 1, wherein the hindered amine compound has a piperidine structure that is not a free radical.   The white ink composition for inkjet according to claim 1 or 2, wherein the hindered amine compound has a piperidine structure in which a nitrogen atom is substituted with a substituted or unsubstituted alkoxy group.   4. The hindered amine compound has a substituent at the 4-position of the piperidine structure, and the substituent includes an ester group, an ether group, or an amino group. White ink composition for inkjet.   The white ink composition for inkjet according to any one of claims 1 to 4, further comprising an ultraviolet absorber.   The white ink composition for inkjet according to claim 5, wherein the ultraviolet absorber is a triazine compound.   The white ink composition for inkjet according to any one of claims 1 to 6, wherein a sodium ion concentration is 200 ppm or less.   An image is formed by applying the white ink composition for inkjet according to any one of claims 1 to 7 on a substrate and irradiating the white ink composition for inkjet with active energy rays. Inkjet recording method.   On an image formed by applying the white ink composition for inkjet according to any one of claims 1 to 7 on a substrate and irradiating the white ink composition for inkjet with active energy rays, An inkjet recording method, further comprising applying an inkjet color ink composition containing at least a colorant and a polymerizable compound.

Images