JP4071244B2 - Method for producing powder dispersion, method for producing pigment dispersion, and method for producing inkjet ink - Google Patents

Description

  The present invention relates to a method for producing a powder dispersion, a method for producing a pigment dispersion, and a method for producing an inkjet ink, and in particular, a powder dispersion and a pigment dispersion from which an inkjet ink excellent in inkjet ejection stability can be obtained. The present invention relates to a manufacturing method and a manufacturing method of such an inkjet ink.

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

  It is known that an on-demand printer uses a solvent-based ink or a solvent-based liquid toner containing a pigment and an organic solvent, similarly to a printer using a plate. In this technique, when a certain number of copies are printed, a non-negligible amount of organic solvent volatilizes. Therefore, there is a problem of atmospheric pollution due to the volatilized organic solvent, and a strict exhaust facility and a solvent recovery mechanism must be provided.

  On the other hand, in an ink jet printer, solvent-based ink can be handled in a closed system until it is discharged onto the printing surface. Moreover, since there is little wasted ink, the problem of atmospheric contamination can be reduced by selecting a relatively safe solvent or by taking appropriate exhaust measures.

  Furthermore, photosensitive ink-jet ink and ink-jet printer systems using the same have begun to attract attention. Typical examples of the photosensitive ink include those containing a radical polymerizable monomer, a photopolymerization initiator, and a pigment (see, for example, Patent Document 1 and Patent Document 2), and the photosensitive ink discharged onto the printing surface. Lightly cure the ink quickly. In addition, photopolymerizable photosensitive inks containing a cation polymerizable monomer, a photo cation generator, and a pigment have been proposed (see, for example, Patent Documents 3, 4, 5, 6, and 7). Since the ink layer can be instantly non-fluidized by light irradiation, a safe and high-quality printed matter can be obtained.

  Ink jet recording apparatuses used for such fast-dry printing applications usually have a print head arranged in a line for printing at a high speed, and printing is performed in one pass on the printing surface. This results in a linear print defect (missing) on the printing surface. Therefore, it is essential to make such errors as zero as possible. That is, the ink used in this way is required to have a material stability for achieving very high printing accuracy and ejection stability.

  The above-mentioned cationic polymerization type ink has been proposed in order to improve the adhesion of the radical polymerization type ink and to improve the low sensitivity due to the reason of the inhibition of curing due to oxygen, and the demand will increase in the future. I think that. However, since these inks have high reactivity, changes in physical properties such as viscosity are essentially large and unstable. This is due to the fact that once an active species is generated for some reason (for example, heat), it is difficult to deactivate and there are many dark reactions of ink.

Further, recent studies have shown that in order to stabilize these inks, it is necessary to stabilize not only the macro but also the micro state. For example, in general, the smaller the particle diameter and the higher the dispersion stability of an ink, the fewer printing errors. Inks containing ionic substances (such as polymerization initiators and surfactants) including inks such as cationic polymerization types generally tend to cause aggregation over time due to an action similar to salting out in a colloidal dispersion system. For this reason, there existed a problem that it was inferior to storage stability. If the components react to change viscosity, surface tension, elastic force, etc., the flying shape of the ink will be disturbed, the print reproducibility will be reduced, and in the worst case, it will easily fall into a fatal state such as ejection failure or ink clogging. The problem was extremely serious.
JP-A-8-62841 JP 2001-272529 A Japanese Patent Publication No. 2-47510 (EUP-0071345-A2) Japanese Patent Laid-Open No. 9-183928 JP 2001-220526 A JP 2000-44857 A Japanese Patent Laid-Open No. 10-250052

  An object of the present invention is to provide a method for producing a powder dispersion suitable for use in inkjet ink for on-demand printing, in particular, having a small viscosity change, stable components, and few problems of dispersion degradation such as pigment aggregation. And Another object of the present invention is to provide a method for producing a pigment dispersion that is suitable for use in inkjet inks for on-demand printing. And It is another object of the present invention to provide a method for producing an ink-jet ink for on-demand printing that has a small change in viscosity, is stable in components, and has few problems of dispersion degradation such as pigment aggregation.

A method for producing a powder dispersion including a powder having an average particle size of 300 nm or less according to one embodiment of the present invention includes a step of adding a powder to the dispersion medium in an amount of 2 parts by weight or more and 60 parts by weight or less.
Adding a first resin dispersant to the dispersion medium in an amount of 1% to 30% with respect to the weight of the powder, and dispersing and coating the powder with the resin;
Adding a second resin dispersant containing a resin having a basic end to 2% to 30% of the powder weight to further disperse the resin-coated powder; and the second resin dispersant. A step of adding 0.01 to 40 parts by weight of the onium salt compound to the dispersion medium to which is added.
A method for producing a powder dispersion containing a powder having an average particle diameter of 300 nm or less according to another embodiment of the present invention is a step of adding a powder in an amount of 2 parts by weight or more and 60 parts by weight or less to a low boiling point organic solvent,
A step of adding a first resin dispersant to the low-boiling organic solvent in an amount of 1% or more and 30% or less with respect to the weight of the powder, and dispersing and coating the powder with a resin to obtain a dispersion precursor. ,
Adding a dispersion medium containing a polymerizable compound to the dispersion precursor, and removing the low-boiling organic solvent;
Adding a second resin dispersant containing a resin having a basic terminal to the dispersion medium in an amount of 2% to 30% based on the weight of the powder to further disperse the resin-coated powder; and The method comprises adding 0.01 parts by weight or more and 40 parts by weight or less of an onium salt compound to the dispersion medium to which the second resin dispersant is added.

A method for producing a pigment dispersion containing a pigment having an average particle diameter of 200 nm or less according to one aspect of the present invention includes a step of adding a pigment to the dispersion medium in an amount of 2 parts by weight or more and 30 parts by weight or less.
Adding a first resin dispersant to the dispersion medium in an amount of 10% or more and 60% or less based on the weight of the pigment, and dispersing and coating the pigment with a resin;
A step of adding a second resin dispersant containing a resin having a basic end to 1% to 30% of the pigment weight to further disperse the resin-coated pigment; and the second resin dispersant added. A step of adding 0.01 parts by weight or more and 20 parts by weight or less of an onium salt compound to the dispersion medium is provided.
A method for producing a pigment dispersion containing a pigment having an average particle diameter of 200 nm or less according to another embodiment of the present invention includes a step of adding a pigment in an amount of 2 to 30 parts by weight to a low boiling point organic solvent,
Adding a first resin dispersant to the low-boiling organic solvent in an amount of 10% or more and 60% or less based on the weight of the pigment, and dispersing and coating the pigment with a resin to obtain a dispersion precursor;
Adding a dispersion medium containing a polymerizable compound to the dispersion precursor, and removing the low-boiling organic solvent;
Adding a second resin dispersant containing a resin having a basic terminal to the dispersion medium in an amount of 1% to 30% based on the pigment weight to further disperse the resin-coated pigment; and The method comprises adding 0.01 parts by weight or more and 20 parts by weight or less of an onium salt compound to the dispersion medium to which the resin dispersant 2 is added.

A method for producing an inkjet ink comprising a pigment having an average particle diameter of 200 nm or less according to one embodiment of the present invention is as follows.
Adding a pigment to the dispersion medium in an amount of 2 to 30 parts by weight;
Adding a first resin dispersant to the dispersion medium in an amount of 10% or more and 60% or less based on the weight of the pigment, and dispersing and coating the pigment with a resin;
A step of adding a second resin dispersant containing a resin having a basic end to 1% to 30% of the pigment weight to further disperse the resin-coated pigment; and the second resin dispersant added. A step of adding 0.01 parts by weight or more and 20 parts by weight or less of an onium salt compound to the dispersion medium is provided.
According to another aspect of the present invention, a method for producing an inkjet ink containing a pigment having an average particle size of 200 nm or less is a step of adding a pigment in an amount of 2 to 30 parts by weight to a low boiling point organic solvent,
Adding a first resin dispersant to the low-boiling organic solvent in an amount of 10% or more and 60% or less based on the weight of the pigment, and dispersing and coating the pigment with a resin to obtain a dispersion precursor;
Adding a dispersion medium containing a polymerizable compound to the dispersion precursor, and removing the low-boiling organic solvent;
Adding a second resin dispersant containing a resin having a basic terminal to the dispersion medium in an amount of 1% to 30% based on the pigment weight to further disperse the resin-coated pigment; and The method comprises adding 0.01 parts by weight or more and 20 parts by weight or less of an onium salt compound to the dispersion medium to which the resin dispersant 2 is added.

  According to the present invention, there is provided a method for producing a powder dispersion that is small in viscosity change, stable in components, has few problems of dispersion deterioration such as pigment aggregation, and is particularly suitable for inkjet ink for on-demand printing. . In addition, according to the present invention, there is provided a method for producing a pigment dispersion that is suitably used for inkjet ink for on-demand printing, particularly with low viscosity change, stable components, and less problems of dispersion degradation such as pigment aggregation. . Furthermore, the present invention provides a method for producing an ink-jet ink for on-demand printing, which has a small viscosity change, a stable component, and less dispersion degradation problems such as pigment aggregation.

  Embodiments of the present invention will be described below.

  The powder dispersion produced by the method according to the embodiment of the present invention is obtained by dispersing a powder in a dispersion medium containing an ionic compound with a specific resin dispersant. Also in the pigment dispersion produced by the method according to the embodiment of the present invention, the pigment is dispersed in the same dispersion medium by a specific resin dispersant.

  The powder contained in the powder dispersion is not particularly limited as long as it has a required optical coloring and coloring function, and any powder can be used. The pigment may further exhibit other properties such as magnetism, fluorescence, conductivity, dielectricity, etc. in addition to coloring / coloring properties. In this case, various functions can be given to the image. Furthermore, a powder capable of improving heat resistance and physical strength can be added.

As the powder exhibiting fluorescence, either an inorganic phosphor or an organic phosphor may be used. Examples of the inorganic phosphor material include MgWO ₄ , CaWO ₄ , (Ca, Zn) (PO ₄ ) ₂ : Ti ⁺ , Ba ₂ P ₂ O ₇ : Ti, BaSi ₂ O ₅ : Pb ²⁺ , Sr _2. Examples include inorganic acid salts such as P ₂ O ₇ : Sn ²⁺ , SrFB ₂ O _3.5 : Eu ²⁺ , MgAl ₁₆ O ₂₇ : Eu ²⁺ , tungstate and sulfurate. Examples of organic phosphor materials include acridine orange, aminoacridine, quinacrine, anilinonaphthalenesulfonic acid derivatives, anthroyloxystearic acid, auramine O, chlorotetracycline, merocyanine, 1,1′-dihexyl-2, Cyanine dyes such as 2'-oxacarbocyanine, dansylsulfoamide, dansylcholine, dansylgalacside, dansyltrizine, dansyl chloride derivatives such as dansyl chloride, diphenylhexatriene, eosin, ε-adenosine, ethidium bromide, fluorescein Fomycin, 4-benzoylamide-4′-aminostilbene-2,2′-sulfonic acid, β-naphthyl triphosphate, oxonol dye, parinaric acid derivative, perylene, N-phenylnaphthy Amine, pyrene, safranine O, fluorescamine, fluorescein isocyanate, 7-chloronitrobenzo-2-oxa-1,3-diasol, dansylaziridine, 5- (iodoacetamidoethyl) aminonaphthalene-1-sulfonic acid, 5- Iodoacetamidofluorescein, N- (1-anilinonaphthyl4) maleimide, N- (7-dimethyl-4-methylcoumanyl) maleimide, N- (3-pyrene) maleimide, eosin-5-iodoacetamide, fluorescein mercury acetate, 2 -(4 '-(2 "-iodoacetamido)) aminonaphthalene-6-sulfonic acid, eosin, rhodamine derivatives, organic EL dyes, organic EL polymers and crystals, and dendrimers.

  Examples of the powder capable of improving the heat resistance and physical strength of the ink layer include aluminum and silicon oxides or nitrides, fillers, and silicon carbide. Further, in order to impart conductivity to the ink layer, powders or nanoparticles such as conductive carbon pigments, carbon fibers, copper, silver, antimony, and noble metals may be added. Iron oxide and ferromagnetic powder are suitable for imparting magnetism, and metal oxide powders such as tantalum and titanium having a high dielectric constant can also be blended.

Furthermore, powders such as natural clay, lead white, zinc white and metal carbonates such as magnesium carbonate, and metal oxides such as barium and titanium are also useful as functional color materials.
The powder as described above is added to the dispersion medium in an amount of 2 wt% to 60 wt% of the total dispersion medium. When the content of the powder is less than 2% by weight, the effect of imparting functionality becomes insufficient, and when it exceeds 60% by weight, the stability of the dispersion is extremely lowered.

  It is desirable that the average particle size of the powder described above be as small as possible so that inkjet discharge can be performed and functions can be expressed. The particle diameter of such a powder is at least 1/3 or less of the opening diameter of the nozzle that discharges the inkjet ink, and more preferably about 1/10. This size is typically 10 μm or less, preferably 5 μm or less. The average particle size of the powder suitable as the inkjet ink for printing is a size of 0.3 μm or less, and usually has an average particle size of several nm to 0.2 μm.

  On the other hand, the method for producing a pigment dispersion according to an embodiment of the present invention can basically obtain an effect by using any pigment, and in particular, in a blue pigment, a black pigment, and a yellow pigment. Is preferred. The average particle diameter of such pigment particles is generally 200 nm or less.

  Examples of blue pigments include metal oxide pigments such as cobalt blue, phthalocyanine pigments, bronze powders, and pigments made of metal powders such as zinc powders. Moreover, a phthalocyanine pigment such as phthalocyanine blue, a selenium pigment such as indatron blue, or an organic pigment can also be used.

  More specifically, examples of pigments that can be used in cyan ink include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15-15: 2, C.I. I. Pigment Blue 15: 3-15: 4, Pigment Blue 15: 5, C.I. I. Pigment Blue 15:34, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 17, C.I. I. Pigment Blue 20, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 25, C.I. I. Pigment Blue 45, C.I. I. Pigment Blue 60, C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Acid Blue 45, C.I. I. Vat Blue 4, and C.I. I. Vat Blue 60 etc. are mentioned. Among these cyan pigments, phthalocyanine pigments that cause little color deterioration with respect to acids are particularly desirable. Furthermore, Pigment Blue 15: 3 is most desirable from the viewpoints of dispersion stability and colorability.

  Moreover, in order to adjust a color, dye can also be added as an auxiliary component of a pigment. For example, dyes having low acidity and basicity and high solubility in solvents, such as azoic dyes, sulfur (building materials) dyes, disperse dyes, fluorescent brighteners, and oil-soluble dyes, are usually used. Of these, oil-soluble dyes such as azo, triarylmethane, anthraquinone, and azine are preferably used. For example, C.I. I. Solvent Blue-2, 11, 12, 25, 35, etc., Diresin Blue-J, A, K, N etc., Orient Oil Blue-IIN, # 603 etc., and Sumiplast Blue BG, etc. can be mentioned.

  The above-mentioned pigments (and dyes) can be used alone or as a mixture of two or more kinds in order to enhance the light absorbency, saturation, color feeling and the like.

  The blue pigment is added to the dispersion medium in an amount of 2% to 30% of the weight of the dispersion medium. If it is less than 2% by weight, a sufficient color density cannot be ensured when it is used as a coloring material in the subsequent processing. On the other hand, if it exceeds 30% by weight, the stability is lowered. Preferably, the content of the blue pigment is in the range of 3% to 27% of the weight of the dispersion medium.

  Examples of black pigments include carbon pigments such as carbon black, carbon refined, and carbon nanotubes, and metal oxide pigments such as iron black, titanium black, and iron oxide. Specifically, carbon black pigments that can be suitably used as the black ink are, for example, Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 1255, manufactured by Cabot Corporation manufactured by Columbia. Regal 400R, Regal 330R, Regal 660R, Mogu L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, No. 1 manufactured by Mitsubishi Chemical Corporation. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B, Color Black FW1, Color Black FW2V, Color Black FW18, Color Black FW18, Color Black FW150, Color Black S150, Color Black S150, Color Black S160, Color Black S160, Color Black FW160, manufactured by Degussa Mention may be made of pigments such as Special Black 6, Special Black 5, Special Black 4A, Special Black 4, and Special Black 250.

  The black pigment is added to the dispersion medium in an amount of 2% to 30% of the weight of the dispersion medium. If it is less than 2% by weight, a sufficient color density cannot be ensured when it is used as a coloring material in the subsequent processing. On the other hand, if it exceeds 30% by weight, the stability is lowered. Preferably, the content of the black pigment is in the range of 3% to 27% of the weight of the dispersion medium. Further, in order to adjust the color, a dye may be added as an auxiliary component as in the case of a cyan pigment.

  Examples of yellow pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, benzimidazolone monoazo pigments), polycyclic pigments (perinone pigments, isoindolinone pigments, isoindoline pigments, It is also possible to use organic pigments such as quinophthalone pigments, and metal complex pigments.

  Examples of pigments that can be used in yellow ink include C.I. I. Yellow 128, C.I. I. Pigment Yellow 129, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 154, C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14C, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 73, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 75, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 98, C.I. I. Pigment Yellow 114, C.I. I. Pigment Yellow 139, C.I. I. Pigment Yellow 180, and C.I. I. Pigment Yellow 150 and the like. Among these yellow pigments, nickel azo pigments or isoindoline pigments are particularly desirable, and Pigment Yellow 150 and Pigment Yellow 139 having excellent dispersion stability are particularly desirable.

  In order to adjust the color, a dye may be added as an auxiliary component as in the case of a cyan pigment. For example, C.I. I. Slope Yellow-2,6,14,15,16,19,21,33,56,61,80 etc., Diresin Yellow-A, F, GRN etc. can be mentioned. In addition, the magenta ink is not as effective as the above-described pigment, but has an effect of suppressing the formation of gel aggregates, and a quinacridone pigment or the like can be preferably used.

  The above-mentioned pigments (and dyes) can be used alone or as a mixture of two or more kinds in order to enhance the light absorbency, saturation, color feeling and the like.

  The yellow pigment is added to the dispersion medium in an amount of 2% to 30% of the weight of the dispersion medium. If it is less than 2% by weight, a sufficient color density cannot be ensured when it is used as a coloring material in the subsequent processing. On the other hand, if it exceeds 30% by weight, the stability is lowered. Preferably, the content of the yellow pigment is in the range of 3% to 27% of the weight of the dispersion medium.

In order to uniformly disperse the powder or pigment as described above in a predetermined amount in the dispersion medium, in the method for producing a dispersion according to the embodiment of the present invention, the first resin dispersant is added to the pigment. After the resin coating is dispersed, a second resin dispersant is added.
The first resin dispersant adsorbs or binds to the surface of the pigment particles, for example, and serves as a barrier for aggregation to prevent aggregation of the pigment particles. Such a pigment can be referred to as a coated pigment coated with a first resin dispersant. Further, the first resin dispersant has an effect of increasing affinity for the dispersion medium and suppressing the precipitation of the pigment particles. Basically, any resin having good affinity for the dispersion medium and steric separation that prevents aggregation of the pigments can be used as the first resin dispersant. For example, at least one selected from vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, fluorine-containing polymers, and epoxy resins. The thing made into a component is mentioned.

In order to act as a dispersant, in such a polymer, the polymer terminal preferably has a binding property or affinity for the pigment. That is, it is desirable that one polymer main chain has an affinity for a solvent and further a physical repulsive force or an electrostatic repulsive force that inhibits recondensation with other pigment particles. For example, it has a solubility parameter equivalent to the dispersion medium (about ± 5 MPa ^1/2 ), has a molecular weight of several hundred to several tens of thousands, a polymerization degree of about 10 to 200, and a Tg of 10 ° C. or more and 200 ° C. or less. The polymer which has is preferable. Furthermore, a polymer having a high affinity for the pigment by having a relatively strong chemical bond (covalent bond, electrostatic force, etc.) at the other end is desirable. Usually, such a composite function can be imparted by using a copolymer of two or several monomers. As such a polymer, a block copolymer can also be suitably used.

  The end of the polymer as described above does not necessarily need to be a single end, but can generally be introduced into a graft copolymerized tip, a tip of a comb polymer, or the like. Such a polymer has a strong bond and easily forms steric hindrance that suppresses reaggregation of pigments.

  Examples of the monomer for synthesizing such a polymer include styrene and substituted styrene, (meth) acrylic acid esters, (meth) acrylic acid, (meth) acrylic amides, maleic acid, maleic anhydride, Mention may be made of maleic acid esters, itaconic acid and its ester compounds, hydroxystyrene and its hydrogen atom-substituted derivatives. A monomer having a long-chain alkyl, a polyether, a polycarbonate, a polyester chain, or the like in the ester side chain is advantageous in forming the aforementioned comb polymer.

  Moreover, the following can also be used as a polymer. For example, polyester compounds obtained by dehydration condensation of dihydroxy compounds such as poly (oxyphthaloyloxymethylene-1,4-phenylenemethylene) and poly (1,4-cyclohexylenedimethylene succinate) and dicarboxylic acids; diamines and dicarboxylic acids such as adipic acid and hexamethylenediamine Polyamides obtained by condensation with acid; Polyamides obtained by ring opening of cyclic lactone such as ε-caprolactam; Comparison among polyamides obtained by condensation of tetracarboxylic acid such as pyromellitic acid and aliphatic diamine Low Tg polymer; polyurethane resin in which aliphatic diisocyanate such as isophorone dicyanate reacts with dihydroxy compound; polyvinylpyridine compound; polydimethylsiloxane and its ladder polymer; polyvinyl alcohol and vinyl ether compound; And relatively rigid polyether oxirane compounds are polymerized with backbone polymers and the like.

  It is preferable that the terminal of these polymers is capped with a compound having a functional group having an affinity for a pigment such as an amino group or a phosphate group. In this case, the adsorptivity to the pigment particle surface is further improved.

  Furthermore, a polymer compound obtained by polymerizing a polymerizable surfactant having a polymerizable group and an amphiphilic property and a crosslinkable monomer and / or a monofunctional monomer is also preferably used as the first resin dispersant. . The polymerizable group in the polymerizable surfactant is preferably an unsaturated hydrocarbon group, and examples thereof include a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, a propenyl group, a vinylidene group, and a vinylene group. These may be used alone or in combination of two or more. The hydrophilic group in the polymerizable surfactant can be selected according to the dispersion medium. When the dispersion medium is aqueous, at least one of a sulfone group, a sulfonic acid group, a carboxyl group, a carbonyl group, a hydroxyl group, and a salt thereof is preferably used. On the other hand, when the dispersion medium is oily, examples thereof include carboxyl groups and esters thereof, lactone compounds, carbonyl groups, and hydroxyl groups.

In order to improve the dispersion stability of the pigment, the surface of the pigment may be modified. This is performed for the purpose of enhancing the binding between the first resin dispersant and the pigment particles. For example, when a carboxyl group having a strong bond with the amino group at the end of a typical dispersant or a sulfonic acid group is partially formed on the surface of the pigment particle, the dispersion stability of the pigment is dramatically improved. Is possible. For example, the pigment surface can be modified with such functional groups by oxidizing the surface of the pigment particles with a suitable oxidizing agent. Or you may employ | adopt the method of making a sulfonating agent etc. act on a pigment particle. Examples of the sulfonating agent that can be used include sulfuric acid, fuming sulfuric acid, SO ₂ , SO ₃ alone or derivatives such as halogenated sulfonic acid. Furthermore, a combination of a catalyst with a rare earth, a highly reactive compound such as an organometallic or vinyl compound having a sulfonic acid group may be used as the sulfonating agent. Furthermore, Strecker's Reaction, which causes a salt such as sodium sulfide to act on the pigment particles that have been subjected to the halogenation treatment, can also be suitably used for the surface modification of the pigment particles.

  On the other hand, when a sulfone-modified pigment (synergist) having a high physical adsorption power to the pigment is adsorbed on the pigment surface, the same surface modification effect may be obtained. Usually, a surface-modified pigment whose surface is directly modified with a sulfonating agent is preferable because it has a better binding force between the pigment and the sulfonic acid group than a synergist and has good dispersion stability. However, even if a synergist is used from the viewpoint of ease of synthesis and cost, there is no problem as long as the stability can be maintained.

  In order to achieve a more powerful surface modification, it is more preferable to perform a microencapsulation treatment in addition to the above-described covalent bond formation between the resin dispersant and the pigment. The microencapsulated pigment can be produced by a known method. For example, phase separation method (coacervation), submerged drying method (interface precipitation method), spray drying method, pan coating method, submerged curing coating method, interfacial polymerization method, in situ method, ultrasonic method, etc. It can be used without particular limitation. More specifically, a method for producing an anionic microencapsulated pigment described in JP-A-9-151342 and a method described in JP-A-10-316909 can be employed.

  In addition, the modification rate by the functional group can be directly measured by a surface spectroscopic analysis method such as EDX when the modifying element contains a sulfur atom, phosphorus or the like, and the target element content is the surface composition of the pigment. It is desirable that it is about 0.1% or more. However, if the modification rate is too large, the acidity of the pigment becomes too strong and reacts with the dispersion medium, which may accelerate aggregation and thickening. Therefore, it may be limited to about 30% at the maximum. preferable. Modification rate such as carboxylic acid which is difficult to obtain by EDX, etc. and resin coverage, surface area determined by adsorption method etc., number of modification groups estimated by titration method, etc., or thermogravimetric analysis to the extent that pigment does not decompose It is possible to estimate from (TG) or the like.

  The first resin dispersant is added in an amount of 1% to 30% with respect to the weight of the powder. In the case of a pigment dispersion, the amount of the first resin dispersant added varies depending on the type of pigment. For example, in the case of a yellow pigment dispersion, it is added in a proportion of 10% to 60% with respect to the pigment weight. In the case of a blue pigment dispersion and a black pigment dispersion, the first resin dispersant Is added in an amount of 10% to 30% with respect to the pigment weight. In any case of the powder dispersion and the pigment dispersion, if the amount of the first resin dispersant added is too small, it is difficult to obtain a sufficient effect. On the other hand, when the amount of the first resin dispersant added is too large, the viscosity of the ink jet dispersion is remarkably increased, or the stability of the dispersion is lowered and reaggregation is likely to occur.

By using the first resin dispersant in an appropriate amount of addition, a resin-coated pigment is produced.
The resin-coated pigment thus obtained can be dispersed in a dispersion medium using a second resin dispersant, and an ionic compound can be added to obtain a stable dispersion by the method according to the embodiment of the present invention. it can.

  The second resin dispersant is a resin having a basic group such as an amino group at its terminal, and preferably has a certain degree of affinity for the first resin dispersant described above. As the second resin dispersant, those capable of generating dispersion stability such as repulsion over the entire pigment particle and the first resin dispersant surrounding the pigment particle by adsorption or interaction of an ionic compound described later are more preferable. desirable.

  The second resin dispersant having such conditions cannot be generally defined by the combination with the first resin dispersant described above, but usually, a polyolefin having an amino terminus, a polyester having an amino terminus, and an amino terminus. And epoxy resin. More specifically, the amine value obtained by reacting a linear polymer having a carboxyl group at one end with a number average molecular weight of 500 to 50,000 and an organic amino compound having one secondary amino group is 5 to 5. Examples include polyepoxy compounds having a number average molecular weight in the range of 1,000 to 100,000 at 200 mg KOH / g. Moreover, a cocondensate of polyester and amide having a free carboxyl group, a cocondensate of polyamide and amide having a free carboxyl group (polyesteramide), and a cocondensate of polyester and amide (polyesteramide) A polyallylamine derivative obtained by reacting one or more compounds selected from the three kinds of compounds with polyallylamine can also be used.

  Furthermore, the following compounds are also included. An amine value obtained by reacting a compound having a carboxyl group at one end with a number average molecular weight of 500 to 50,000 and a compound having one secondary amino group is 5 to 200 mg KOH / g, and the number average molecular weight is 1000 to 100,000. A polyester-based polymer having an amino group in the range: a tertiary amino group and / or an amine polymer obtained by reacting an acrylic polymer having a basic nitrogen-containing heterocyclic ring with polyester, 10 to 200 mgKOH / g, Polyester polymers having amino groups with a number average molecular weight in the range of 1,000 to 100,000.

  Examples of the polyepoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol. And polyglycidyl ether compounds such as polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, and sorbitol polyglycidyl ether. Furthermore, the glycidyl ester group containing acrylic polymer etc. which are obtained by the copolymerization of glycidyl (meth) acrylate and other polymerizable vinyl monomers are mentioned. In this case, methyl methacrylate, styrene, or the like can be used as the polymerizable vinyl monomer.

  The second resin dispersant is added in an amount of 2% to 30% of the powder weight. When deviating from this range, a powder dispersion having an appropriate viscosity cannot be obtained in a stable dispersion state. Specifically, when the content of the second resin dispersant is small, the dispersion stability is remarkably impaired. On the other hand, when the second resin dispersant is too much, the dispersion becomes viscous. In particular, ejection stability is impaired in inkjet applications. The more preferable range of the resin weight may cause a slight difference depending on the type of pigment or powder. For example, in the case of a blue pigment and a black pigment, they are added in an amount of 5% to 30%, more preferably 10% to 20%, based on the pigment weight. In the case of a yellow pigment, it is added in an amount of 1% to 30% with respect to the pigment weight. In the case of the pigment dispersion as well, as in the case of the powder dispersion, if the amount of the second resin dispersant is too small, the dispersion stability is significantly impaired. On the other hand, when there is too much 2nd resin dispersing agent, a dispersion becomes viscous and discharge stability is impaired.

  After the second resin dispersant is thus added, an ionic compound is further added. For example, an ionic compound containing a polyvalent salt has an action of destabilizing (salting out or aggregating) the colloidal dispersion system. When such an ionic compound containing a polyvalent salt is added directly to the pigment coated with the first resin dispersant described above, the dispersion stability of the pigment particles is significantly reduced. In contrast, in the method according to the embodiment of the present invention, since the second resin dispersant is already added in addition to the first resin dispersant, the ionic compound is dispersed in the second resin dispersion. Acts with agents. As a result, a stable charge can be generated on the pigment surface, and a stable dispersion can be obtained.

  Examples of such ionic compounds include the following compounds that can be used for stabilizing inks, thickeners, anti-drip agents, antifoaming agents, and the like. Specifically, organic compounds soluble salts and organic salts such as metal salts and carbonates, organic-inorganic salts such as metal soaps as surfactants and dispersion aids, and ammonium compounds such as alkyl ammonium typified by organic electrolytes Fluoroborate anion, hexafluoroantimonate anion, hexafluoroarsenate anion, trifluoromethanesulfonate anion, paratoluenesulfonate anion, perchlorate anion, halogen anion, sulfonate anion-containing compound, carboxylate anion-containing compound, etc. Salts selected from organic solvent-soluble ammonium salts and the like.

  When producing a powder dispersion, the ionic compound is added in a proportion of 0.01% to 40% of the total weight of the dispersion medium. In the case of a pigment dispersion, the ionic compound is dispersed. It is added at a ratio of 0.01% to 20% of the total weight of the medium. More preferably, it is 1% or more and 20% or less. In any case, when the content of the ionic compound is too small, the effect cannot be sufficiently exhibited. On the other hand, when the content of the ionic compound is too large, the stability of the dispersion deteriorates and reaggregation tends to occur.

  The dispersion produced by the method according to the embodiment of the present invention is applied to a photocurable liquid ink. In this ink, an onium salt compound is suitably used as a photoacid generator that generates an acid by light irradiation. It is done. Since the onium salt compound is a typical organic salt, it can be suitably used as an ionic compound in the dispersion.

  Examples of onium salts that can be used include fluoroborate anion, hexafluoroantimonate anion, hexafluoroarsenate anion, trifluoromethanesulfonate anion, paratoluenesulfonate anion, and paranitrotoluenesulfonate anion, halogen anion, sulfonate anion. And diazonium salts, phosphonium salts, sulfonium salts, and iodonium salts having a carboxylic acid anion and a sulfate anion as a counter ion. Among these, from the viewpoint of the stability of the color material and environmental considerations, the anion species preferably does not contain boron, antimony, arsenic, etc., and among them, the fluoroborate anion is most desirable.

  More specific examples of such onium salt compounds include, for example, compounds represented by the following chemical formula.

  Examples of commercially available onium salt compounds include MPI-103 (CAS.NO. (87709-41-9) manufactured by Midori Chemical Co., Ltd.) and BDS-105 (CAS.NO. (145612-66-4) manufactured by Midori Chemical Co., Ltd.). ), NDS-103 (CAS.NO. (110098-97-0)), Midori Chemical Co., Ltd., MDS-203 (CAS.NO. (127855-15-5)), Midori Chemical Co., Ltd., DTS- 102 (CAS.NO. (75482-18-7)), Midori Chemical Co., Ltd. DTS-103 (CAS.NO. (71449-78-0)), Midori Chemical Co., Ltd. MDS-103 (CAS.NO. (127279) -74-7)), MDS-105 (CAS.NO. (116808-67-4)) manufactured by Midori Chemical Co., Ltd., MDS-205 (CAS.N manufactured by Midori Chemical Co., Ltd.) (81416-37-7)), BMS-105 (CAS.NO. (149934-68-9)) manufactured by Midori Chemical Co., Ltd., and TMS-105 (CAS.NO. (127820-38-6) manufactured by Midori Chemical Co., Ltd.) ), UVACURE 1591 and 1590 manufactured by Daicel UCB, UVI-6992 and 6976 manufactured by Dow Chemical Company, ESACURE-1064 manufactured by Lamberti, and IRGACURE 250 manufactured by Ciba Geigy.

  Among the onium salts described above, sulfonium salts and iodonium salts are excellent in stability. However, due to the production process, it is usually inevitable that a monovalent salt (a salt of a monovalent cation and a single anion) and a salt of a bivalent or higher (for example, a divalent cation) up to about 75%. It is known to include mixtures with salts with two anions. In general, commercially available products are also in the state of such a mixture, and this tendency is particularly noticeable with sulfonium salts. It is known that when a polyvalent salt is contained in the ink, the photosensitive wavelength shifts to the long wavelength side, and generally the sensitivity becomes high. In order to ensure such advantages, a divalent or higher salt may be intentionally mixed. For example, commercially available products such as UVACURE1591 and 1590 manufactured by Daicel UCB, UVI-6992 and 6976 manufactured by Dow Chemical Company, and ESACURE-1064 manufactured by Lamberti are applicable. However, polyvalent salts have a significant effect on the aggregation stability of ink jet pigment dispersions that in particular require fine particles. Specifically, the polyvalent salt also has a disadvantage that it causes a weak bond between the pigment particles and the dispersant, thereby causing a gel or an aggregate. For this reason, usually, suppressing the presence of these polyvalent salts as much as possible leads to an improvement in the dispersion stability of the pigment particles and the ejection performance of the ink jet.

  The content of the polyvalent onium salt is usually preferably 20 parts by weight or less of the total amount of the onium salt. The content of the polyvalent onium salt is more preferably 5 parts by weight or less, and most preferably it is not contained.

  Among the onium salt compounds described above, an arylsulfonium fluorophosphate salt or an aryliodonium fluorophosphate salt is desirable because the aggregation stability of the color pigment is remarkably excellent. Moreover, even if it is a monovalent onium salt, when a dispersing agent is insufficient, it has the effect | action which gradually substitutes the terminal amine resin which is a dispersing agent with time. For this reason, it is desirable that the onium salt has a structure that is as difficult to approach as possible to the bonding portion between the pigment surface and the end of the dispersant. This is possible by using an onium salt compound having a relatively large substituent in the structure. Furthermore, in order to reduce ion adsorption on the pigment surface due to steric hindrance, the benzene ring in the onium salt preferably has an organic group having 1 to 20 carbon atoms. More preferably, 50 mol% or more of the benzene rings have an organic group having 4 to 20 carbon atoms. In this case, in addition to dispersion stability, the safety of the product is improved because the decomposition products are prevented from scattering into the air during the photoreaction. Since such a compound has high solubility in a solvent, a phenomenon such as precipitation of a salt in the ink can be suppressed. As a result, the generation of several micron-sized particles that tend to cause ejection failure is also reduced, which is very desirable.

  When a monovalent onium salt is used, the sensitivity wavelength tends to shift to the short wavelength side, so that the sensitivity tends to decrease. It is desirable that an aromatic substituent having a VI element such as sulfur or oxygen in the heterocyclic ring or as a linking group is included in the structure, since such inconvenience can be avoided.

  Furthermore, as shown in the following general formula (1) or (2), in the case of an onium salt containing a relatively large organic group in the structure, it has an advantage of high dissolution stability and good dispersion stability. Have

Here, A ⁻ is a fluorophosphate anion. At least one of R ₁ , R ₂ , and R ₃ is an organic group having 4 to 20 carbon atoms, and the rest is an organic group having 1 to 20 carbon atoms including a hydrogen atom. R ₄ represents a divalent aromatic substituent or a divalent aromatic substituent containing a VI atom in the structure.

Examples of organic groups that can be introduced as R ₁ to R ₃ include alkyl groups having 4 to 20 carbon atoms such as propyl group, butyl group, hexyl group, heptyl group, octyl group, nonyl group, and decanyl group, and propyloxy group. , A butyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decanyloxy group, etc., an alkyloxy group having 4 to 20 carbon atoms, and a polyethylene oxide skeleton having a polyethylene oxide skeleton obtained by dehydration condensation of ethylene glycol. And the like.

Examples of the divalent aromatic substituent that can be introduced as R ₄ include groups having phenylene such as phenylene and biphenylene; groups having a phenylene sulfide skeleton such as phenylene sulfide and phenylene disulfide; benzothiophenylene, thio And groups having a thiophene skeleton such as phenylene and bithiophenylene groups; and groups having a furan skeleton such as furanylene and benzofuranylene.

  It is also known that the above-described onium salt suppresses the generation of harmful by-products such as benzene in the process of photoreaction. By using a dispersion containing such an onium salt as an inkjet ink, it can be desirable because of its high environmental and safety effects.

  A powder or pigment as described above is added to the dispersion medium in a predetermined amount, and a predetermined amount of the first resin dispersant is added to disperse the resin. Thereafter, a predetermined amount of the second resin dispersant is added and further dispersed, and a predetermined amount of the ionic compound is added, and a powder dispersion or a pigment dispersion is produced by the method according to the embodiment of the present invention. . Such a dispersion is diluted with an inkjet ink solvent, an additive or the like is added, and an inkjet ink is manufactured by the method according to the embodiment of the present invention. The dispersion medium for preparing the dispersion is desirably the same as the solvent for preparing the inkjet ink. In some cases, a low boiling point solvent or the like may be used as a dispersion medium of the dispersion, and after adding a solvent for adjusting the ink jet ink, the low boiling point dispersion medium may be removed. The inkjet ink solvent may be a general oil-based ink solvent or a radical polymerization type ink solvent, but when it is a cationic polymerization type (chemical amplification type) solvent, a photoacid generator and an ionic compound are used together. This is desirable.

  Here, “inkjet ink” means an ink having fluidity at room temperature. Specifically, the ink has a viscosity at 25 ° C. of 50 cp (= mPa · s), more preferably 30 mPa · sec or less, and is used for inkjet applications. In addition, when the temperature of the ink jet head can be adjusted, it is more preferable that the ink has a viscosity of 5 to 20 mPa · sec at the temperature adjustment temperature of the head.

  In the following, the dispersion medium of the dispersion is basically described, but an explanation as a solvent for inkjet ink is also described. The dispersion medium is most preferably a compound that polymerizes in the presence of an acid used in a photocurable cationic inkjet ink, but other photocurable inkjet inks, solvents used as general oil-based inkjet inks, and solid inkjets. Even when an ink or many organic solvents (intermediate solvents) used in an intermediate process of ink processing are used, a suitable dispersion in which pigment particles are stably dispersed can be obtained. Oil-based inks prepared using such a dispersion are desirable because of less ejection errors. Examples of the intermediate solvent include low boiling point organic solvents such as methyl ethyl ketone, acetone, and xylene. As the solvent for the oil-based ink, an ink that has a certain degree of solubility in an organic salt compound and has an ink viscosity in the range of 5 to 20 mPa · sec at the temperature control temperature of the head (usually 35 to 60 ° C.) is desirable. The solid ink-jet ink desirably has a certain degree of solubility in organic salt compounds and has a fluidity of about 100 mPa · s or less at 50 ° C. or less.

  Such compounds include monohydric or polyhydric alcohols having a relatively large carbon number, ester / etherified compounds thereof, and terminal alcohols such as adducts of ethylene glycol and propylene glycol such as poly (ethylene glycol). And polyether compounds, aliphatic compounds having a relatively large number of carbon atoms, and esters such as lactic acid esters.

  More specifically, decanol, dodecanol, oleyl alcohol, stearoyl alcohol, hexadecanol, eicosanol), polyhydric alcohol (eg, ethylene glycol, alcohol, diethylene glycol (DEG), triethylene glycol, propylene glycol, tetraethylene glycol, Polyethylene glycol, glycerol, 2-methyl-2,4-pentanediol, 2-ethyl-2-hydroxymethyl-1,3-propanediol (EHMP), 1,5-pentanediol, 1,2-hexanediol, 1 , 2,6-hexanetriol, and thioglycol), lower alkyl monoethers or diethers derived from alkylene glycols (eg, monomethyl ether of ethylene glycol or Monoethyl ether, monomethyl ether or monoethyl ether of diethylene glycol, monomethyl ether or monoethyl ether of propylene glycol, monomethyl ether or monoethyl ether of triethylene glycol, dimethyl ether or diethyl ether of diethylene glycol, monobutyl ether of polyethylene glycol (PEGMBE), And diethylene glycol monobutyl ether (DEGMBE)), nitrogen-containing compounds (eg urea, 2-pyrrolidinone, N-methyl-2-pyrrolidinone, and 1,3-dimethyl-2-imidazolidinone), and sulfur-containing compounds (eg , Dimethyl sulfoxide and tetramethylene sulfone).

  As the paraffin hydrocarbon solvent, normal paraffin hydrocarbons such as octane, nonane, decane and dodecane; isoparaffin hydrocarbons such as isooctane, isodecane and isododecane; cycloparaffin hydrocarbons such as cyclohexane, cyclooctane, cyclodecane and decalin Etc. Commercially available products include, for example, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M, Exol D130, Exol D140 (all of which are manufactured by Exxon Chemical), Shellsol (manufactured by Shell Oil), Saltol ( Philips Petroleum), Vegasol (Mobil Petroleum), IP Solbend 2835 (Idemitsu Petrochemical), Moresco White P-40, Moresco White P-55 (all of which are manufactured by Matsumura Oil Research Co., Ltd.) , Liquid paraffin No. 40-S, and liquid paraffin No. 55-S (all of which are manufactured by Chuo Kasei Co., Ltd.).

  As the solvent-based ink, those having a relatively low boiling point are used, and as the oil-based ink, those having a low volatility having a boiling point of 200 ° C. or more are preferably used. In the solid inkjet ink, among the above-described compounds, those having extremely small fluidity at room temperature can be used.

  Depending on the printing medium to which the ink is applied, the following penetrating solvent or a highly volatile solvent may be further added. For example, low molecular alcohols (eg, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, s-butyl alcohol, t-butyl alcohol, isobutyl alcohol, furfuryl alcohol, and tetrahydrofurfuryl alcohol) , Ketones or keto alcohols (eg, acetone, methyl ethyl ketone, and diacetone alcohol), ethers (eg, tetrahydrofuran and dioxane), and esters (eg, ethyl lactate, ethylene carbonate, and propylene carbonate), and the like. Such a solvent can also be added in the case of a solvent-based ink.

  As described above, since the photoacid generator and the ionic compound among the constituent components can be used together, the dispersion medium is most preferably a compound that polymerizes in the presence of an acid. When such a compound is used, printed matter imparted with high photosensitivity and high adhesion can be produced. Therefore, the dispersion medium may be substantially composed of a polymerizable compound having such characteristics. “The dispersion medium consists essentially of a polymerizable compound” means that “the dispersion medium consists only of a polymerizable compound” and “consists of a trace amount of impurities inevitably mixed with the polymerizable compound”. Include. Further, “a trace amount of impurities inevitably mixed” can be present in the entire dispersion medium at a concentration of 10% by weight or less. Preferably, it is usually 5% by weight or less. If the concentration of impurities exceeds 10% by weight, the remaining dispersion medium is substantially scattered in the air, which may reduce safety. Moreover, there exists a possibility that it may remain inside hardened | cured material and hardening performance may fall.

  The polymerizable compound that polymerizes in the presence of an acid desirably has a fluidity of about 100 mPa · s or less at 50 ° C. or less. Examples of such compounds include compounds having a molecular weight of 1000 or less having cyclic ether groups such as epoxy groups, oxetane groups, oxolane groups, acrylic or vinyl compounds having the above-mentioned substituents in the side chain, carbonate compounds, low molecular weights. Monomers having a vinyl bond capable of cationic polymerization such as melamine compounds, vinyl ethers and vinyl carbazoles, styrene derivatives, alpha-methyl styrene derivatives, vinyl alcohol esters including vinyl alcohol and acrylic, methacrylic ester compounds, etc. Can be used together.

  The powder dispersion and the pigment dispersion produced by the method according to the embodiment of the present invention may have any viscosity. In particular, for application to inkjet applications, as a practical viscosity that can be used by diluting until the viscosity of the ink at the temperature control temperature of the head is in the range of 5 to 20 mPa · sec, the viscosity at 25 ° C. is several hundred mPa. -It is desirable that it be less than s.

  In the embodiment of the present invention, the dispersion medium may have any viscosity. In particular, in order to apply to inkjet applications in which low viscosity is important, the main component is a compound having a viscosity at 25 ° C. of 300 mPa · s or less and a boiling point of 150 ° C. or more at 1 atm even in a mixture. It is desirable to do. Here, the main component means that 70% or more, more desirably 80% or more of the total amount of the dispersion medium is the property. By defining the upper limit of the viscosity of the dispersion medium, the dispersibility of the pigment particles can be improved and sufficient fluidity can be imparted. Moreover, by defining the lower limit of the boiling point, it is possible to reduce harmful volatile components contained in the dispersion as much as possible. When the viscosity of the dispersion medium exceeds 300 mPa · sec, the stability of the dispersion deteriorates, and in particular, when processed as an inkjet ink, normal ink ejection becomes difficult.

  When the polymerizable compound that polymerizes in the presence of an acid has an aliphatic skeleton or an alicyclic skeleton, when used together with the other components described above, the transparency of the ink-jet ink at the time of exposure is enhanced, and the ink after curing Appropriate thermoplasticity and re-solubility can be imparted to the layer. Therefore, the performance such as sensitivity, fixability, transferability, and maintainability is improved. In particular, when the polymerizable compound is an epoxy compound having an alicyclic skeleton, in addition to reactivity, a certain degree of high boiling point and low viscosity can be achieved.

  When the acid polymerizable compound is an epoxy compound, for example, at least one terminal of a hydrocarbon group having a divalent aliphatic skeleton or alicyclic skeleton having about 1 to 15 carbon atoms is bonded to an epoxy group or an alicyclic group. The compound which has an epoxy group can be mentioned. In addition, a compound having an epoxy group or an alicyclic epoxy group at at least one terminal of a divalent group having an aliphatic chain or an alicyclic skeleton in part can also be used.

  If the epoxy compound having such conditions is contained in the solvent at a concentration of at least 40% by weight, the effect can be exhibited. In the case where the solvent is composed of only the epoxy compound, the content is preferably 30% by weight or more, more preferably 40% by weight or more based on the entire liquid ink. If it is less than 30% by weight, there is a possibility that nozzle clogging may occur.

  The number of epoxy groups introduced into the molecular skeleton as described above is not particularly limited, but in order to impart flexibility and re-solubility to the ink layer after curing, a valence of about 2 to 3 at most. It is desirable to do. As such an epoxy compound, the compound represented by the following general formula (3) or (4) can be mentioned, for example.

In the above general formulas (3) and (4), R ²¹ , R ²² and R ²³ each represents an epoxy group or an epoxy group having an alicyclic skeleton, and A ²¹ and A ²² represent a functional group.

The viscosity of the compound represented by the general formula (3) or (4) is usually about 1 mPa · sec to 300 mPa · sec.
The epoxy compound represented by the general formula (3) or (4) may be used together with the epoxy compound represented by the following general formula (5). The epoxy compound represented by the following general formula (5) is usually a high viscosity compound having a viscosity of about 20 mPa · sec to 1000 mPa · sec. Therefore, the use of this compound is effective for imparting flexibility or ultimate hardness to the ink layer after curing.

In the general formula (5), R ²⁴ and R ²⁵ each represents an epoxy group or an epoxy group having an alicyclic skeleton, and A ²³ represents an k + 1-valent functional group having at least an alkylene group and / or an alicyclic skeleton. (K is a natural number).

  For example, 40 parts by weight to 90 parts by weight of an epoxy compound having a low viscosity (15 mPa · sec or less) and 10 parts by weight to 50 parts by weight of a compound having a high viscosity epoxy (15 mPa · sec or more) with respect to 100 parts by weight of the liquid ink. When blended at a ratio of 1, it is advantageous for realizing the minimum fluidity required for ejection (viscosity of 50 mPa · sec or less at 50 ° C.). In particular, the weight ratio of the low viscosity epoxy compound to the high viscosity compound is preferably about 1: 1 to 10: 1. As a result, it is possible to obtain a liquid ink having all the characteristics of viscosity, photocurability, thermoplasticity, and redissolvability suitable for ejection.

  If the amount is small, a compound having a relatively high molecular weight, for example, a solid such as a solid at room temperature, may be contained in the dispersion medium to constitute a part of the dispersion medium. By containing such components, it is possible to improve the flexibility of the ink layer after curing and the dispersibility of the pigment. Further, when a highly reactive compound having a large valence is used, the hardness and solvent resistance of the cured product can be increased. Examples of such a compound include a compound having a molecular weight of 5000 or less having a cyclic ether group such as an epoxy group, an oxetane group or an oxolane group bonded by a long chain alkylene group; Acrylic or vinyl compounds; carbonate compounds; low molecular weight melanin compounds; vinyl alcohol esters such as vinyl ethers, vinyl carbazoles, styrene derivatives, alpha-methyl styrene derivatives, ester compounds of vinyl alcohol with acrylic, methacryl, etc. A monomer having a cationically polymerizable vinyl bond and an oligomer obtained by polymerizing at least one of the monomers.

  In addition to the above-mentioned compounds, the dispersion medium may be a vinyl alcohol homopolymer or copolymer; molecular weight 5000 having acid-reactive / dehydrating-condensable OH groups, COOH groups, acetal groups, etc. such as casein and cellulose. The following resins; Polycarbonate resins having a molecular weight of 5000 or less; Copolymers of polyamic acid, polyamino acid or acrylic acid and vinyl compounds having acid-polymerizable double bonds in the side chains; A compound selected from the group consisting of a copolymer with a vinyl compound having a heavy bond; and a methylolated melamine compound, a polymer having a terminal hydroxyl group (ester oligomer) and the like may further be contained.

  In particular, when preparing an inkjet ink having the following specific composition, at least 50 parts by weight of the solvent has an alicyclic skeleton having a viscosity of 20 mPa · s or less at normal temperature and pressure and a boiling point of 150 ° C. or more. And / or an acid-polymerizable compound having an aliphatic skeleton. Specifically, the content of the photoacid generator in the ink is 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the solvent that is polymerized in the presence of an acid, and a pigment is used as a color component It is. In this case, some of the carbon atoms of the aliphatic skeleton and / or the alicyclic skeleton may be oxidized or substituted with oxygen.

  As described above, the number of epoxy groups introduced into the molecular skeleton of the acid-polymerizable compound having an alicyclic skeleton and / or an aliphatic skeleton is not particularly limited. In order to impart solubility, a valence of about 2 to 3 is desirable. Usually, these are a mixture of compounds having a viscosity equal to or higher than a low-viscosity compound having a viscosity of about 1 mPa · s to 30 mPa · s. However, if the low-viscosity compound is excessively contained, there is a possibility that the ejection of the ink jet may be disturbed or the volatility may be increased. Therefore, it is desirable that the upper limit of the content be 90% by weight.

  On the other hand, from the viewpoint of safety, in the case of an aliphatic epoxy compound, an epoxy compound having an alicyclic skeleton having a relatively low mutagenicity is desirable because it has a higher carbon number and a higher molecular weight because the mutagenicity is lower. It is desirable to use it at the center.

  Examples of the alicyclic epoxy compound include limonene (di) oxide, oxabicycloheptane, α-pinene oxide, (3,4'-epoxycyclohexane) methyl 3,4-epoxycyclohexanecarboxylate, 4-vinylcyclohexene-1, 2 epoxide and the like and substituted compounds thereof. Examples of the epoxy compound having an aliphatic skeleton include compounds having one or more glycidyl ether groups in an aliphatic skeleton having 2 or more carbon atoms. For example, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, glycerol di (tri) glycidyl ether, 1,6-hexanediol diglycidyl ether, decane glycidyl ether, and the like. Also included are hydrogenated bisphenol A, novolac, and glycidyl etherified compounds of biphenol. Since such a compound generally has a high viscosity, it is desired to use it together with a lower viscosity epoxy compound.

  More specifically, as a trade name, Daicel Chemical's Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2081, Celoxide 2000, Celoxide 3000, and a (meth) acrylate compound having an epoxy group are exemplified. A cyclomer A200, a cyclomer M100, a methacrylate having a methyl glycidyl group such as MGMA, a low molecular weight epoxy compound glycidol, β-methylepicholorhydrin, α-pinene oxide, a C12 to C14 α-olefin mono Epoxides, C16-C18 alpha-olefin monoepoxides, epoxidized soybean oil such as Daimac S-300K, epoxidized linseed oil such as Daimac L-500, Epolide GT301, and Or the like can be mentioned a multifunctional epoxy such as Epolead GT401.

  Furthermore, Cyracure (American Dow Chemical Co., Ltd., alicyclic epoxy compound), hydrogenated and aliphatic low-molecular-weight phenol compounds substituted with hydroxyl groups at the end of epoxy groups, ethylene glycol, glycerin, neopentyl Use glycidyl ether compounds such as polyhydric aliphatic alcohols / alicyclic alcohols such as alcohol, hexanediol, trimethylolpropane, glycidyl esters of hexahydrophthalic acid, and glycidyl esters of hydrogenated aromatic polycarboxylic acids. be able to.

  Further, in order to improve the chemical resistance of the image, a transparent liquid epoxy resin having high weather resistance and high Tg may be added. Examples of such resins include epoxidized polybutadiene such as Epolide PB3600 and PB3600M manufactured by Daicel Chemical Industries, EHPE3150, and EHPE3150CE. Alternatively, in addition to these, a lactone-modified alicyclic epoxy resin may be used in combination. Examples thereof include Plaxels GL61, GL62, G101, G102, G105, G401, G402, and G403X manufactured by Daicel Corporation.

  Among these, compounds obtained by modifying Celoxide 2000, Celoxide 3000, α-pinene oxide, ethylene glycol, glycerin, neopentyl alcohol or hexanediol alcohol to glycidyl ether are desirable from the viewpoints of viscosity and volatility. In particular, limonene dioxide (product name: Celoxide 3000) and α-pinene oxide starting from natural products are desirable in terms of viscosity and reactivity.

  In addition, the characteristic requested | required of printed matter changes according to the use. For example, when the printed material is used for the exterior of a can or a plastic bottle or the exterior of a container made of an oily material, the printed image is required to have solvent resistance and high adhesion. In such a case, in addition to the alicyclic epoxy compound and the aliphatic epoxy compound, a compound having a phenolic hydroxyl group as described above, for example, a glycidyl ether compound of bisphenol A, phenol novolac, polyhydroxystyrene, and the like An appropriate amount of a phenolic oligomer glycidyl ether compound or a general aromatic epoxy compound such as styrene oxide can be added.

  Furthermore, when resistance to a solvent is required at the same time as printing at a high speed of, for example, several tens of meters per minute, this can be achieved by using an oxetane compound as a solvent polymerized with an acid. However, when an aromatic oxetane compound is used as the main component of the solvent, the viscosity of the inkjet ink is significantly increased. In order to avoid this, it is desirable to add an aliphatic or cycloaliphatic oxetane compound. Such oxetane may be a (poly) alkylene oxide or oxolane structure containing an ether bond in a part of its aliphatic chain or alicyclic structure. Considering viscosity suitability, the content of the aromatic oxetane compound is preferably in the range of 0 to 40 parts by weight.

  However, when the printed material is required to have resistance to a solvent having higher solubility, the content of the aromatic oxetane compound can be increased beyond the above-described range. In that case, since an increase in viscosity is caused, it is desirable to use a low-viscosity epoxy compound, a compound having an oxetane in the acrylic side chain, or a low-viscosity compound such as a vinyl ether compound in combination.

  Examples of the divalent or higher valent aliphatic or alicyclic oxetane compound include (di [1-ethyl (3-oxetanyl)] methyl ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, [( 1 or more alicyclic rings such as 1-ethyl-3-oxetanyl) methoxy] cyclohexane, bis [(1-ethyl-3-oxetanyl) methoxy] cyclohexane and bis [(1-ethyl-3-oxetanyl) methoxy] norbornane In addition, a compound in which an oxetane-containing group is introduced may be used, and an oxetane-containing alcohol such as 3-ethyl-3-hydroxymethyloxetane may be dehydrated into an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol, or neopentyl alcohol. Condensed ether compounds can also be used.

  Examples of the oxetane compound containing an aromatic skeleton include 1,4-bis ((1-ethyl-3oxetanyl) methoxy) benzene, 1,3-bis ((1-ethyl-3oxetanyl) methoxy) benzene, 4, 4'-bis ((3-ethyl-3oxetanyl) methoxy) biphenyl, and phenol novolac oxetanes.

  Among these compounds, [1-ethyl (3-oxetanyl)] methyl ether is preferably used because of its low viscosity. When an acrylic compound or a methacrylic compound having an oxetane group in the side chain is used, in addition to suppressing an increase in viscosity, the same curing acceleration effect as that of the oxetane compound can be obtained.

  In the case where further reduction in viscosity and improvement in curing hardness are required in addition to improvement in the curing speed and solvent resistance of the printed image, a vinyl ether compound represented by the following general formula (6) is similarly blended in the inkjet ink. It is preferable to do. Such vinyl ether compounds can be used alone or in combination.

In the general formula (6), at least one R ¹³ is a group having a vinyl ether skeleton, and represents a substituent selected from a vinyl ether group and a hydroxyl group. R ¹⁴ is a p + 1 valent group selected from an alicyclic skeleton, a cyclic ether compound, a terpenoid skeleton, or an aromatic skeleton, and p is a positive integer including 0.

  In general, vinyl ether compounds bonded to methylene groups such as aliphatic glycol derivatives and cyclohexanedimethanol are generally well known. Such a polymerization reaction of the vinyl ether compound is remarkably inhibited by the pigment and has a relatively high viscosity, so far it has been difficult to blend it as an ink component. In the vinyl ether compound represented by the general formula (6), at least one vinyl ether group is directly bonded to the alicyclic skeleton, the cyclic ether compound, the terpenoid skeleton, or the aromatic skeleton, and may be contained together with the pigment. Excellent curing performance.

  Such a vinyl ether compound can be used in combination with the aforementioned epoxy compound or oxetane compound. Or you may comprise the whole quantity of the acid polymerizable compound as a solvent with this vinyl ether compound.

In the general formula (6), examples of the (p + 1) -valent organic group R ¹⁴ include a (p + 1) -valent group including a benzene ring, a naphthalene ring, and a biphenyl ring, a cycloalkane skeleton, a norbornane skeleton, an adamantane skeleton, And (p + 1) -valent groups derived from bridged alicyclic compounds such as a cyclodencan skeleton, a tetracyclododecane skeleton, a terpenoid skeleton, and a cholesterol skeleton.

  More specifically, cyclohexane (poly) ol, norbornane (poly) ol, tricyclodecane (poly) ol, adamantane (poly) ol, benzene (poly) ol, naphthalene (poly) ol, anthracene (poly) ol, Examples thereof include alicyclic polyols such as biphenyl (poly) ol, and compounds in which a hydrogen atom of a hydroxyl group in a phenol derivative is substituted with a vinyl group. Moreover, the compound etc. which substituted the hydrogen atom of the hydroxyl group in polyphenol compounds, such as polyvinyl phenol and a phenol novolak, by the vinyl group can also be used. The compound as described above has no problem even if a part of the hydroxyl group remains, or a part of the methylene atom of the alicyclic skeleton is oxidized or substituted with a ketone group, a lactone, an oxygen atom or the like. In such a case, volatility is reduced, which is desirable.

  In particular, since a cyclohexyl monovinyl ether compound is rich in volatility, when a cyclohexyl monovinyl ether compound is used, it is desirable that the cyclohexane ring is oxidized to at least a cyclohexanone ring or the like.

  Among such compounds, a cyclic ether compound having a substituent containing a vinyl ether structure is more preferable. In terms of curability and safety, a cyclic ether skeleton containing a five-membered ring skeleton containing an oxygen atom and simultaneously having a bridged structure and a spiro structure is most suitable. Such a vinyl ether compound is obtained by replacing the alcohol with vinyl ether using a corresponding alcohol compound and a vinyl ether source such as vinyl acetate or propenyl ether as starting materials, for example, using a catalyst such as iridium chloride (J. Am. Chem.Soc.Vol124, No8, 1590-1591 (2002)).

  Among the above-described compounds, epoxy compounds, oxetane compounds, and vinyl ether compounds having a naturally occurring skeleton such as a terpenoid skeleton and a norbornane skeleton are favorable in terms of cost.

  In the method according to the embodiment of the present invention, as a dispersion medium for preparing a dispersion, a radical polymerizable solvent can be used in addition to a general oil-based ink solvent or a cationic polymerizable solvent. The radical polymerizable solvent can also be applied as a solvent for a photocurable inkjet ink by blending a photoradical generator.

  Examples of the radical polymerizable solvent include generally known mono-polyol acrylic or methacrylic ester compounds. Since monoacrylate has high safety, an acrylate or methacrylate compound having a terpenoid skeleton in the ester side chain is preferably used. For example, an acrylic compound as disclosed in JP-A-08-82925 is preferably used as the monomer. For example, terpene doubles having unsaturated bonds such as myrcene, carene, osymene, pinene, limonene, camphene, terpinolene, tricyclene, terpinene, fenchen, ferrandlene, sylvestrene, sabinene, dipentene, bornene, isopulegol, or carvone. An ester compound in which the bond is epoxidized and acrylic acid or methacrylic acid is added is exemplified. Or citronellol, pinocamphetol, geraniol, fentil alcohol, nerol, borneol, isoborneol, linalool, menthol, terpineol, twill alcohol, citronellal, yonon, iron, cinerol, citral, pinol, cyclocitral, carbomenton, ascari Terpenes such as Dole, Safranal, Piperitol, Mentenmonool, Dihydrocarvone, Carveol, Sclareol, Manol, Hinokiol, Ferguinol, Totarol, Sugiol, Farnesol, Patchouliol, Nerolidol, Carotol, Casinol, Lanceol, Eudesmol or Phytol Ester compounds of alcohol derived from acrylic acid or methacrylic acid may be used . In addition, general acrylates and methacrylate compounds such as alkyl acrylates, hydroxyethyl acrylates, and acrylates having an alicyclic epoxy in the side chain can be exemplified for improving adhesion and the like.

  Moreover, in order to improve the reactivity of the monomer mentioned above, polyfunctional acrylates can also be used. For example, a polyacrylate compound of a polyhydric alcohol compound, a polyacrylate compound of a polyvalent aromatic alcohol, a polyacrylate compound of a polyvalent alicyclic alcohol, and a styrene compound having a substituent may be mentioned. Examples of such monomers include ethylene glycol, polyethylene glycol, propylene glycol, glycerin, neopentyl alcohol, trimethylol propane, pentaerythritol, di-polyacrylate compounds such as vinyl alcohol oligomers, urethane acrylate compounds, phenol and cresol. , Naphthol, bisphenol, and their novolak condensation compounds and di-polyacrylate compounds of vinylphenol oligomers, and hydrogenated cyclohexane, hydrogenated bisphenol, decahydronaphthalene alicyclic ring, and terpene alicyclic ring And dicyclopentane and tricyclodecane alicyclic di-polyhydroxy compound di-polyacrylate compound. A compound in which the acrylate moiety of such a compound is substituted with a group containing vinyl ether can also be suitably used.

  Specific examples of divalent or higher acrylate compounds include the following. For example, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, 2-n-butyl-2-ethyl-1,3-propanediol diacrylate, dipropylene Glycol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, triethylene glycol diacrylate, 3-methyl-1,5-pentanediol diacrylate, 2-methyl-1,8-octanediol acrylate and 1,9 -Nonanediol diacrylate mixture, dimethylol tricyclodecane diacrylate, hydroxypivalate neopentyl glycol diacrylate, polytetramethylene glycol diacrylate, trimethylol propane tri Chryrate, pentaerythritol triacrylate, pentaerythritol triacrylate, trimethylolpropane EO adduct triacrylate, EO-modified trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, glycerin PO-added triacrylate, glycerin propoxytriacrylate, trisacryloyl Examples thereof include oxyethyl phosphate, pentaerythritol tetraacrylate, pentaerythritol ethoxytetraacrylate, polyethylene glycol diacrylate, and urethane acrylates.

  Furthermore, V # 195, V # 230, V # 260, V # 265, V # 310HP, V # 335HP, V # 295, V # 300, V # 360, V of Osaka Organic Chemical Industry Co., Ltd. #GPT, V # 3PA, V # 400, Daicel UCB's HDODA, DPGDA, TPGDA, PEG300DA, PEG400DA, Ebecryl11, IRR214, TMPTA, PETIA, Ebecryl160, Ebecryl2047, OTA480, EbecrylLite, 40 Acrylate 1.6HX-A, Light acrylate 1.9ND-A, Light acrylate BEPG-A, Light acrylate 3EG-A, Light acrylate 4EG-A, Light acrylate 9EG-A, Light acrylate 14EG-A, Light acrylate NP-A, Light acrylate MPD-A, Light acrylate MOD-A, Light acrylate DCP-A, Light acrylate HPP-A, Light acrylate PTMGA-250, Light acrylate TMP-A, Light acrylate PE -3A, light acrylate TMP-3EO-A, light acrylate TMP-6EO-A, and light acrylate PE-4A.

  In addition to the compounds described above, a compound having an olefin structure as a substituent can also be used as the radical polymerizable compound. In general, an aliphatic compound having an olefin in its structure is particularly suitably used when it has a poor polymerization property and has an olefin skeleton or a styrene skeleton having a highly distorted ring structure such as a 5-membered ring as a substituent. For example, the above-described series of alcohols and monomer compounds having maleic acid or norbornene skeleton, or monomers in which some hydrogen atoms of styrene or hydroxystyrene are converted to substituents having other aliphatic hydrocarbons such as terpenoid skeleton Etc. are desirable.

When the radically polymerizable compound as described above is used as a solvent, it is desirable that the inkjet ink further contains a photoradical generator. As the photoradical generator, for example, a photoradical polymerization initiator such as Michler's ketone or benzophenone known by trade names Irgacure or Darocur (Nagase Sangyo) can be used. More specifically, for example, benzophenone, acetophenone derivatives such as α-hydroxy- or α-aminocetophenone, 4-aroyl-1,3-dioxolane, benzyl ketal, 2,2-diethoxyacetophenone, p-dimethyl Aminoacetophene, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, pp'-dichlorobenzophene, pp'-bisdiethylaminobenzophenone, Michler's ketone, benzyl, benzoin, benzyldimethyl ketal, tetramethylthiuram monosulfide, thioxanthone 2-chlorothioxanthone, 2-methylthioxanthone, azobisisobutyronitrile, benzoin peroxide, di-tert-butyl peroxide, 1-hydroxycyclohexane Silphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, methylbenzoyl formate, zoin isopropyl Ether, benzoin methyl ether, benzoin ethyl ether, ben ether, benzoin isobutyl ether, benzoin n-butyl ether, benzoin alkyl ethers and esters such as benzoin n-propyl, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-benzyl- 2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,1-hydroxy-cyclohexyl-phenyl-ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, bis (η ⁵ -2,4-cyclo Pentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2- Methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur 1173), bis (2,6 -Dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one monoacyl Phosphine oxide, bisacylphosphine oxide or titanocene, fluorescene, anthraquinone, thioxanthone or Xanthone, lophine dimer, trihalomethyl compound or dihalomethyl compound, activated ester compound, and an organic boron compound, and the like.

  Specific product names include, for example, IRGACURE 379, IRGACURE 127, IRGACURE 369, and IRGACURE 907 manufactured by Ciba Geigy. In addition to these compounds, polymerization promoting additives such as diethanolamines may be contained.

  The dispersion produced by the method according to the embodiment of the present invention is diluted with a solvent as described above, and further, if necessary, a photopolymerization initiator such as a photoacid generator or a photoradical generator, an additive, etc. Ink jet ink is prepared by the method according to the embodiment of the present invention.

  As the photoacid generator, the onium salts described above can be used. The content of the photoacid generator in the inkjet ink can be set according to the acid generation efficiency of the photoacid generator used, the content of the pigment, and the like. From the viewpoint of photosensitivity, the photoacid generator is usually 2 to 10 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of all solvents polymerized with acid in the ink jet. Preferably, it is added at a ratio of 2 to 6 parts by weight.

  In particular, when a sensitizer is blended at the same time, the amount of photoacid generator added can be reduced to about 1 to 4 parts by weight. As a result, corrosion of metal members such as pipes and head members is reduced, which is more desirable. In addition, when a photoradical generator is included at the same time, in many cases, a sensitizing action for photoradical generation can also be imparted at the same time. Examples of the sensitizing dye include acridine compounds, benzoflavins, perylenes, anthracenes, thioxanthone compounds, and laser dyes. Among them, a compound in which a hydrogen atom of dihydroxyanthracene is substituted with an organic group, a thioxanthone derivative, and the like are desirable because they are contained and have high effects. The addition amount of the sensitizing dye is usually 20% by weight to 100% by weight, and more preferably 30% by weight to 60% by weight with respect to the photopolymerization initiator.

  When the ratio of the photopolymerization initiator to 100 parts by weight of the solvent in the ink-jet ink is less than 1 part by weight, the sensitivity of the ink-jet ink is lowered. On the other hand, when the amount exceeds 10 parts by weight, the viscosity of the ink over time increases due to dispersion deterioration and dark polymerization of the solvent, and the coating properties and the hardness of the ink film after photocuring may decrease. Further, corrosion of piping and head members of the recording apparatus may occur.

  As the photoacid generator, a nonpolar photoacid generator that generates another relatively strong acid can be blended at the same time. As such a compound, a photoacid generator selected from any of sulfonyl compounds, sulfonate compounds, sulfamide compounds, and organic halogen compounds is desirable. Of these, compounds that generate strong fluoromethanesulfonic acid, hydrochloric acid, and bromic acid are desirable as the photoacid generator.

  Specifically, examples of the nonpolar photoacid generator include organic halogenated compounds such as sulfamide compounds such as trifluoromethanesulfonic acid imide of N-hydroxynaphthalimide and halogenated triazine compounds. For example, it is preferable to mix 0.3 to 2 parts by weight of the onium salt compound and 2 to 10 parts by weight of the nonpolar photoacid generator with respect to 100 parts by weight of the solvent.

  The inkjet ink produced by the method according to the embodiment of the present invention can be applied to inkjet recording. In the case of oil-based ink, the recording medium is mainly an absorbing medium, and a residual image is formed on the absorbing medium and used as it is as a printed matter. Further, when a solvent having a drying property is used, the solvent evaporates to form an ink layer on the recording medium.

  In the case of the photosensitive inkjet ink, when the obtained ink layer is irradiated with light, radicals or acids are generated from the photopolymerization initiator, and these function as an initiator for a chain reaction of a polymerizable compound and a catalyst for a crosslinking reaction. In the photosensitive inkjet ink, the above-described polymerizable compound is used as at least a part of the solvent, and typically almost the entire amount of the solvent is composed of the polymerizable compound. If the ratio of the polymerizable compound to the entire solvent is sufficiently high, the organic solvent hardly volatilizes during printing. Therefore, it is possible to prevent the problem of atmospheric pollution caused by the volatilization of the organic solvent, and an exhaust facility and a solvent recovery mechanism are not required.

  The acid generated in the latter chemically amplified ink diffuses in the ink layer and functions as a catalyst. The acid diffusion and acid-catalyzed crosslinking reaction can be accelerated by heating, and this crosslinking reaction is not inhibited by the presence of oxygen, unlike radical polymerization. Therefore, a plurality of cross-linking reactions can be caused by one photon, and high sensitivity can be obtained. In addition, since the crosslinking reaction proceeds rapidly even in the deep part of the ink layer or inside the absorbent recording medium, the obtained ink layer is also excellent in adhesion compared to the radical polymerization system.

  Therefore, when such an ink-jet ink is used, the ink layer can be quickly non-fluidized by performing light irradiation and slight heating after ejecting the ink onto the printing surface. That is, a high-quality printed material can be obtained without requiring a large-scale exposure system. The obtained non-flowable film desirably exhibits thermoplasticity (it is reflowable by heat, and the property duration may be short).

  In addition, unlike such ink jet inks that utilize radical polymerization, such ink jet inks do not require the use of radical polymerizable monomers that have great skin irritation and odor. Therefore, the inkjet ink manufactured by the method according to the present embodiment is easy to handle.

  As described above, the chemically amplified ink does not need to use an organic solvent, and can quickly make the ink layer non-fluid. As a result, it is possible to easily fix an image with almost no blurring on various printing surfaces having different properties. In addition, it is difficult for the printed surface to deteriorate due to the drying of the ink layer. Furthermore, since the inkjet ink manufactured by the method according to the present embodiment can contain a pigment as a color component at a high concentration, it is possible to form a clear print pattern with excellent weather resistance.

Among the ink-jet inks produced by the method according to the embodiment of the present invention, the chemically amplified ink is basically a photosensitive ink that needs to be heated. Therefore, the volatility of the ink from the viewpoint of safety and odor. Is desired to be low. Specifically, the volatilization rate after exposure and at 80 ° C. is desirably 0.2 mg / cm ² · min or less. The volatilization amount here indicates the volatilization amount (mg) per minute when a container having an opening area of 10 cm ² is heated, for example. This value depends on the opening of the container, but is usually defined as a value when 4 g of ink is contained in a petri dish having a diameter of 6 cm and heated under normal pressure. Ink with a composition that deviates from this range has a too high volatilization rate at the time of heating, which impairs safety and causes a significant odor problem. On the other hand, in the case of ink with extremely low volatility, for example, 0.00001 mg / cm ² · min or less, the viscosity is usually high and ink jet ejection is often difficult.

As described above, the inkjet ink produced by the method according to the embodiment of the present invention has a fluidity of 5 to 20 mPa · sec at the head temperature, at least 50 mPa · sec at room temperature, more preferably 30 mPa · sec. It is desirable to have it. In order to ensure such fluidity, when n kinds of acid polymerizable compounds are mixed and contained, η _t represented by the following formula (1) is 3 (mPa · s) or more and 30 (mPa · s). The composition is preferably within the range of 5 (mPa · s) to 20 (mPa · s) at the head temperature.

_{χ 1, χ 2, χ 3} , ···, it is chi _n, the weight composition ratio of each _{component, η 1, η 2, η} 3 ···, η n is a normal temperature and pressure of each component alone Of the viscosity.
If it deviates from this range, the ejection of the ink becomes extremely difficult, or the image is liable to be disturbed due to the ejection disorder.

  The ink-jet ink produced by the method according to the embodiment of the present invention is cured by irradiating light to form an ink layer. If the cured ink layer has sufficient thermoplasticity and re-solubility, the liquid ink is ejected onto the image carrier to form an ink layer, which is then transferred onto the recording medium. can do. That is, ink jet ink is ejected onto the image carrier to form an ink layer, and the ink layer is cured by light irradiation and heating. Further, by applying pressure or pressure and heat while the recording medium is in contact with the ink layer, it can be reflowed or plasticized and transferred onto the recording medium.

  In addition, when the inkjet ink is directly discharged onto the recording medium, the ink layer formed on the recording medium is cured or precured by irradiating light and heating. Further, the ink layer can be permanently cured by applying heat to be fixed on the recording medium.

  The inkjet ink produced by the method according to the embodiment of the present invention is desired to have high stability of inkjet ejection, but generally there is a tendency that viscosity increase with time tends to be high, and performance may not be maintained over a long period of time. is there. In such a case, it is desirable to further blend at least one of a basic compound and a compound expressing basicity as a viscosity stabilizer. The basic compound also has the effect of significantly reducing corrosion from acid in the ink jet head of the recording apparatus and the metal portion of the ink pipe. For this reason, it is preferable to add a basic compound to the general inkjet ink manufactured by the method concerning embodiment of this invention.

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

An ammonium compound can also be used as the basic compound. Preferred ammonium compounds include quaternary ammonium salts. For example, as a substituent of the ammonium atom, methyl, a ethyl, propyl, isopropyl, butyl, dodecyl, phenyl, benzyl, etc., the counterion is hydroxide ion, ^- a OR (R is an alkyl of 1 to 4 carbon atoms ^group), - OCOR '(R' is alkyl, aryl, ^alkylaryl), OCOO ^-, OSOO - anion represented by is preferably used. Particularly preferable examples include tetramethylammonium hydroxide and tetrabutylammonium hydroxide salt. These basic compounds can be used alone or as a mixture of two or more.

  When a very strong basic compound such as imidazole is blended, there is a possibility that, for example, polymerization with time will occur, or side reactions such as decomposition of the photoacid generator may occur. On the other hand, if the compound is too low in basicity, it will be difficult to obtain a sufficient viscosity stabilizing effect by addition. For example, a basic compound having a base dissociation constant pKb of 4 or more at a temperature of 25 ° C. in a suitable aqueous solution is desirable, and a compound having a pKb of more than 11 shows little effect. As the compound satisfying such conditions, for example, pyridine derivatives, aniline derivatives, aminonaphthalene derivatives, other nitrogen-containing heterocyclic compounds and derivatives thereof are suitable.

  Examples of the pyridine derivative include 2-fluoropyridine, 3-fluoropyridine, 2-chloropyridine, 3-chloropyridine, 3-phenylpyridine, 2-benzylpyridine, 2-formylpyridine, and 2- (2′-pyridyl). Examples thereof include pyridine, 3-acetylpyridine, 2-bromopyridine, 3-bromopyridine, 2-iodopyridine, 3-iodopyridine, and 2,6-di-tert-butylpyridine.

  Examples of aniline derivatives include aniline, 4- (p-aminobenzoyl) aniline, 4-benzylaniline, 4-chloro-N, N-dimethylaniline, 3-5-dibromoaniline, 2,4-dichloroaniline, N , N-dimethylaniline, N, N-dimethyl-3-nitroaniline, N-ethylaniline, 2-fluoroaniline, 3-fluoroaniline, 4-fluoroaniline, 2-iodoaniline, N-methylaniline, 4-methylthio Aniline, 2-bromoaniline, 3-bromoaniline, 4-bromoaniline, 4-bromo-N, N-dimethylaniline, 2-chloroaniline, 3-chloroaniline, 4-chloroaniline, 3-chloro-N, N -Dimethylaniline, 3-nitroaniline, 4-nitroaniline, 2-methoxyaniline, 3 Methoxyaniline, diphenylamine, 2-biphenylamine, o-toluidine, m-toluidine, p-toluidine, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, and 4,4'-bis (4- And aminophenoxy) diphenylsulfone.

  Examples of aminonaphthalene derivatives include 1-amino-6-hydroxynaphthalene, 1-naphthylamine, 2-naphthylamine, diethylaminonaphthalene, and N-methyl-1-naphthylamine.

  Examples of other nitrogen heterocyclic compounds and derivatives thereof include, for example, sinoline, 3-acetylpiperidine, pyrazine, 2-methylpyrazine, methylaminopyrazine, pyridazine, 2-aminopyrimidine, 2-amino-4,6-dimethylpyrimidine, 2-amino-5-nitropyrimidine, 2,4,6-triamino-1,3,5-triazine, pyrrole, pyrazole, 1-methylpyrazole, 1,2,4-triazole, indazole, benzotriazole, quinazoline, quinoline 3-aminoquinoline, 3-bromoquinoline, 8-carboxyquinoline, 3-hydroxyquinoline, 6-methoxyquinoline, 5-methylquinoline, quinoxaline, thiazole, 2-aminothiazole, 3,4-diazaindole, purine, 8-azapurine, indole And it can be exemplified India such as lysine.

Among these, when the basic compound is an aniline derivative, it is particularly desirable in terms of viscosity stability, volatility, basicity, and low side reactivity.
However, since an aniline compound has low basicity, it is generally not desirable in combination with an oxetane compound in which the compound itself has basicity. As the oxetane compound, a compound having higher basicity is desirable, for example, a compound having a pKb at 25 ° C. of 7 or less and 3 or more. More specifically, a basic compound such as an amine having an aliphatic skeleton or an amine having an alicyclic skeleton can be preferably used.

  Moreover, when the basic compound as described above forms a salt with an anion and the acidity of the anion is low, the compound itself can act as a weak base and can be used in the same manner.

  Since the inkjet ink produced by the method according to the embodiment of the present invention basically requires post-exposure heating, it is desirable that the basic compound as described above is also as low in volatility as possible. Specifically, the boiling point of the basic compound is desirably 150 ° C. or higher, more preferably 180 ° C. or higher at normal temperature.

  The blending amount of the basic compound or the compound that expresses basicity is desirably 30 mol% or less and 1 mol% or more with respect to the total molar amount of the photoacid generator. More preferably, it is 15 mol% or less and 2 mol% or more with respect to the total number of moles of the photoacid generator. When the compounding amount of such a compound is too large, the sensitivity is remarkably lowered, and when the compounding amount is too small, the viscosity stabilizing effect may not be sufficiently obtained.

When a photosensitive basic compound that is decomposed by irradiation with light or radiation is used, a decrease in sensitivity due to the addition of a base can be reduced, which is desirable.
As the photosensitive basic compound, a sulfonium compound or an iodonium compound can be preferably used. Examples of the sulfonium compound include compounds represented by the following general formulas (SS1), (SS2), (SS3), and (SS4).

(Wherein R ³¹ , R ³² and R ³³ are each an alkyl group, aryl group, heteroaryl group, or alkyl group, alkylaryl group, halogen atom, alkoxy group, phenoxy group, thiophenol group, phenylsulfonyl group. Or an aryl group substituted by a phenylsulfenyl group, and Y is CH ₂ , O, or S. R ³⁴ , R ³⁵ , R ³⁶ , and R ³⁷ are each an alkyl group, an alkoxy group, or a halogen atom in and, X1 ^- represents a basic anion).
R ³¹ , R ³² and R ³³ are preferably methyl, ethyl, propyl, isopropyl, butyl, phenyl, biphenyl, tolyl, xylyl, chlorophenyl, bromophenyl, methoxy Examples include phenyl group, ethoxyphenyl group, propyloxyphenyl group, butyloxyphenyl group, tert-butyloxyphenyl group, phenoxyphenyl group, thiophenoxyphenyl group, phenoxyphenyl group, thiophenoxyphenyl group, and phenylsulfonylphenyl group. .

R ³⁴ , R ³⁵ , R ³⁶ and R ³⁷ are preferably an alkyl group, a methoxy group, an ethoxy group, a chlorine atom or a bromine atom.

X1 ^- The, hydroxyl ^ion, - OR (alkyl group R is ^{C1~C4), - OCOR '(R} ' is an alkyl group, an aryl group or an alkyl aryl ^group), OCOO ^-, OSOO - anion represented by the Can be mentioned.

  As the iodonium compound, compounds represented by the following general formulas (IS1), (IS2), (IS3), and (IS4) are preferable.

In the above general formula, R ³⁸ and R ³⁹ are each an alkyl group, aryl group, heteroaryl group, or alkyl group, aryl group, halogen atom, alkoxy group, phenoxy group, thiophenol group, phenylsulfonyl group or phenylsulfenyl group. An aryl group mono-, di- or tri-substituted by a group. Y is CH ₂ , O or S, R ⁴⁰ , R ⁴¹ , R ⁴² and R ⁴³ are each an alkyl group, an alkoxy group or a halogen atom, n is 5 or 6, and X 2 ⁻ is a basic group. Anion.

R ³⁸ and R ³⁹ are preferably methyl, ethyl, propyl, isopropyl, butyl, phenyl, biphenyl, tolyl, xylyl, chlorophenyl, bromophenyl, methoxyphenyl, ethoxy Examples include phenyl group, propyloxyphenyl group, butyloxyphenyl group, tert-butyloxyphenyl group, phenoxyphenyl group, thiophenoxyphenyl group, phenoxyphenyl group, thiophenoxyphenyl group, and phenylsulfonylphenyl group.

R ⁴⁰ , R ⁴¹ , R ⁴² and R ⁴³ are preferably an alkyl group, a methoxy group, an ethoxy group, a chlorine atom or a bromine atom.

X2 ^- as preferably hydroxyl ^ion, - OR is C1~C4 alkyl ^base, - OCOR '(R' is an alkyl group, an aryl group, alkylaryl ^group), OCOO ^-, OSOO - include anions represented by .

  Particularly preferable examples of the sulfonium compound and the iodonium compound include triphenylsulfonium acetate, triphenylsulfonium hydroxide, triphenylsulfonium phenolate, tris- (4-methylphenyl) sulfonium hydroxide, and tris- (4-methyl). Phenyl) sulfonium acetate, tris- (4-methylphenyl) sulfonium phenolate, diphenyliodonium hydroxide, diphenyliodonium acetate, diphenyliodonium phenolate, bis- (4-t-butylphenyl) iodonium hydroxide, bis- (4- t-butylphenyl) iodonium acetate, bis- (4-t-butylphenyl) iodonium phenolate, thiophenyl substituted triphenylsulfonium acetate DOO, and triphenyl sulfonium hydroxide and the like, which is thiophenyl substituted.

  In addition to the basic compounds described above, other basic compounds can also be added. In order to obtain good results in terms of sensitivity and storage stability, it is preferable that the photoacid generator and the basic compound are the same kind of compounds, such as sulfonium compounds and iodonium compounds.

  Alternatively, when a compound that is not basic in nature is decomposed with time to produce a basic compound, it is desirable because the acid that is gradually generated can be neutralized. As such a compound, a compound that generates a base by heat can be used. For example, NBC-101 (trade name: manufactured by Midori Chemical Co., Ltd.) and α, α-dimethyl-3,5-dimethoxybenzylcarbamate. And carbamate compounds.

  Furthermore, in order to adjust the surface tension and the like, a small amount of a low molecular additive such as a nonionic or ionic surfactant or charging agent is added to the inkjet ink produced by the method according to the embodiment of the present invention. can do. When a cationic additive is used as the low molecular additive, it is desirable to select a compound having a lower acidity than the carboxylic acid. This is because some cationic additives promote the curing dark reaction of the ink. Further, low molecular additives and pigments having strong basicity may not only lower the sensitivity of the ink, but also promote the curing dark reaction. In order to avoid such inconvenience, it is desirable that the low molecular additive is near neutral or nonionic.

  When the printing surface is strongly basic, the ink-jet ink produced by the method according to the embodiment of the present invention can reduce the influence thereof by, for example, further blending the above-mentioned radical polymerizable compound. . This is applicable even when the pigment or the printing surface is easily affected by acid. Examples of the radical polymerizable compound include acrylic or methacrylic monomers, styrene monomers, and compounds having a plurality of vinyl polymerizable groups thereof. Moreover, when it contains a vinyl ether compound, it can be combined with an acrylic monomer or can be radically polymerized alone. Similarly, a compound having both cationic polymerizable and radical polymerizable properties, such as CEL2000 manufactured by Daicel Chemical Industries, epoxy cyclohexyl (meth) acrylate, glycidyl methacrylate, vinyl alcohol derivatives and acrylic, methacrylic ester compounds, etc. When added, the advantages of radical polymerizability and cationic polymerizability are obtained. In this case, a photoradical polymerization initiator such as Michler's ketone or benzophenone known by the above-mentioned trade name Irgacure and a photocrosslinking radical generator such as bisazide can be contained at the same time. Such a method can also be applied when it is desired to impart higher chemical resistance to the cured ink layer.

  The ink-jet ink produced by the method according to this embodiment is usually desired to contain as little volatile components as water or an organic solvent as much as possible. However, among the above-mentioned general organic solvents, for example, organic solvents and moisture used in the preparation of raw materials such as methyl ethyl ketone, propylene glycol solvent, ethyl lactate, xylene, water, etc. are inevitable if they are in trace amounts. It may be mixed in. For example, when an exhaust mechanism and a solvent recovery mechanism are provided, a small amount of an organic solvent may be contained for the purpose of obtaining a desired printed matter. In this case, from the viewpoint of safety, it is desirable to use components such as water, alcohols, isoper and terpene.

  Among the ink-jet inks produced by the method according to the present embodiment, those that depend on the chemical amplification mechanism for the image forming ability generate an acid from the photoacid generator by exposure, and the acid diffuses by heating. It functions as a catalyst for crosslinking reaction or decomposition reaction. For this reason, in this ink-jet ink, the presence of significant basic ions causes a decrease in sensitivity. Therefore, it is desirable to take care not to mix a large amount of basic ions not only in the preparation process of the liquid ink but also in the manufacturing process of each component.

  Next, with reference to the drawings, a printing method and a recording method with a heating mechanism that can be used for the chemically amplified ink among the above-described recording apparatuses using the inkjet ink will be described.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  As described above, the pigment used in the inkjet ink as described above has other properties such as magnetism, fluorescence, conductivity, dielectricity, and electromagnetic heat generation in addition to coloring and coloring properties. May be further indicated. When an inkjet ink containing such a pigment is used, various functions can be imparted to the printed matter. Some examples are shown below.

First, an ink-jet ink containing a pigment having magnetism will be described.
First, an ink-jet ink containing magnetic powder as a pigment is prepared. This ink-jet ink can basically be prepared by the same method as described above. That is, a dispersion is prepared by the same method except that the pigment is changed to magnetic powder, and this is diluted to obtain an inkjet ink. As the magnetic powder, for example, iron, cobalt, nickel, and alloys and oxides thereof can be used.

  Next, the inkjet ink is ejected onto a recording medium to draw a pattern such as a barcode pattern. Immediately after ink ejection, the ink layer is irradiated with light such as ultraviolet rays. The irradiation amount at this time can be set according to the pigment content in the ink-jet ink, its photosensitivity, and the like, and is usually about several hundred mJ to several thousand mJ. Even when the ink layer is in a state immediately after light irradiation, the tackiness and fluidity of the ink layer are lost, but the ink layer can be completely cured by maintaining the temperature in the stocker at room temperature to 60 ° C. Since the cured ink layer has magnetism, secondary information other than image information can be read by a magnetic detection mechanism such as a magnetic head.

Next, an inkjet ink containing a conductive pigment will be described.
First, an inkjet ink containing conductive powder as a pigment is prepared. In order to prepare this inkjet ink, a dispersion containing a conductive pigment is prepared. Examples of the conductive pigment include silver, gold, copper, aluminum, carbon, nickel, iron, cobalt, lead, tin, antimony, an alloy powder of any combination thereof, and a composite of these and organic matter. It is done. That is, an inkjet ink containing a conductive pigment can be produced by the same method as described above except that such a conductive pigment is used. For the purpose of reducing the resin content in the finally obtained ink layer and increasing the conductivity, the content of the polymerizable compound in the inkjet ink may be reduced, and an organic solvent may be added to the inkjet ink.

  The obtained ink-jet ink is discharged onto a recording medium such as an insulating substrate to draw a pattern such as a line pattern. Immediately after ink ejection, the ink layer is irradiated with light such as ultraviolet rays. The irradiation amount at this time can be set according to the content of the pigment in the ink-jet ink and its photosensitivity, and is usually about several hundred mJ to several hundreds mJ. Even when the ink layer is in a state immediately after light irradiation, the adhesiveness and fluidity of the ink layer are lost, but the ink layer can be completely cured by maintaining the temperature in the stocker at room temperature to 60 ° C. Further, when heat and pressure are applied to the ink layer, the conductivity is further increased. Furthermore, when an alloy powder having a relatively low melting point is used as the conductive pigment, the conductive layer can be obtained by heating the ink layer to its flow temperature. Since the printed pattern thus obtained has conductivity, it can be used as a circuit pattern or a resistance pattern.

  Furthermore, when an inkjet ink containing a dielectric powder such as barium lead, bismuth, iridium, ruthenium, tantalum, platinum, titanium, strontium, chromium, or an oxide thereof, or a ceramic powder is used, It is also possible to form a dielectric layer of a capacitor or an inductor. In this case, the characteristics may be improved by baking after pattern formation. In addition, when an inkjet ink containing a pigment having a photocatalytic function and a bactericidal ability such as titanium oxide powder is used, it is possible to form a printed pattern having such a function. Examples of the electromagnetic wave heat generating powder include electromagnetic wave heat generating ceramics and silicon resin. These can be used for purposes such as selectively heating a print portion by irradiating electromagnetic waves. Such a powder can be used for improving the electromagnetic wave heating property of the inkjet ink as described above.

  In addition, it is possible to form an overprint or a relatively thick print pattern using such an ink. In other words, an image having a raised portion capable of partial correction of printing and tactile image recognition by repeating ejection of inkjet ink and curing of the ink layer obtained thereby in a predetermined area of the recording medium a plurality of times. For example, a print pattern for handicap users such as Braille, a print pattern such as a topographic map with the thickness changed corresponding to the contour line, and a part of a device having a thickness of several tens of μm or more are formed. It is also possible to do.

Hereinafter, embodiments of the present invention will be described in detail with specific examples.
Various pigment dispersions were produced using a blue pigment, a black pigment, and a yellow pigment.

The blue pigment dispersion was produced by the following two methods using Pigment Blue 15: 3 as a pigment.

(C-2)
Pigment Blue 15: 3, a polyester resin having a terminal amino group as a first resin dispersant (Abyssia: Solsperse 32000), and 1/10 amount of synergist (Abyssia, Solsperse 5000) with respect to the polyester resin. And added to MEK as a preliminary dispersion medium. The obtained mixture was pre-dispersed with a homogenizer. Then, the surface coating pigment MEK solution (dispersion precursor) was obtained by circulating treatment with 0.1 mm zirconia beads and a bead mill (Shinmaru Enterprises Co., Ltd.) at a circumference of 8 m / sec for 2 hours. Various MEK solutions were prepared in the same manner except that the ratio of the first resin dispersant to the pigment was changed.

  When this dispersion precursor was dried and observed using a TEM (transmission electron microscope), it was confirmed that a film made of a polyester resin was formed on the surface of the pigment. Although some polyester resins were found to remain without adsorbing on the pigment surface, the exact resin coverage was identified as follows. That is, re-dispersion by centrifugation-decantation and ultrasonic waves (24 KHz 300 W) was repeated. As a result, a pigment dispersion in which excess resin was washed away was produced. The exact resin coating amount was identified by thermal analysis (TG) of the pigment in this dispersion, and is shown in Table 1 below.

  An equivalent amount of a solvent as the present dispersion medium was added to each dispersion precursor. After stirring this for 1 hour, it was heated for 1 hour while stirring at 50 ° C. and 50 mmHg, and further heated for 3 hours at 5 mmHg to remove MEK. Thus, various pigment dispersions as shown in Table 1 below were produced.

(C-3)
Permajet Blue B2G (Clariant) was added to MEK and pre-dispersed with a homogenizer. Thereafter, circulation was performed with 0.1 mm zirconia beads and a bead mill at a circumference of 8 m / sec for 2 hours to obtain a MEK solution (dispersion precursor) of a surface-coated pigment.

  When this dispersion precursor was dried and observed with a TEM (transmission electron microscope), it was confirmed that a film made of a vinyl chloride / vinyl acetate copolymer was formed on the surface of the pigment. Although it was found that some of the resins (copolymers) were detached from the pigment surface, the exact resin coating amount was identified as follows. That is, re-dispersion by centrifugation-decantation and ultrasonic waves (24 KHz 300 W) was repeated. As a result, a pigment dispersion in which excess resin was washed away was produced. The exact resin coating amount was identified by subjecting the pigment in this dispersion to thermal analysis (TG) and described in Table 1 below.

  An equivalent amount of a solvent as the present dispersion medium was added to each dispersion precursor. After stirring this for 1 hour, it was heated for 1 hour while stirring at 50 ° C. and 50 mmHg, and further heated for 3 hours at 5 mmHg to remove MEK. Thus, various pigment dispersions as shown in Table 1 below were produced.

The black pigment dispersion was produced by the following method using Special Black 250 (Degussa: carbon black) as a pigment.
Special Black 250 (Degussa: carbon black), a polyester resin having a terminal amino group as a first resin dispersant (Abyssia: Solsperse 32000), and 1/10 amount of synergist (Abyssia) with respect to this polyester resin Co., Ltd., Solsperse 5000) was added to MEK as a pre-dispersion medium at various dispersant resin ratios with respect to the pigment, and pre-dispersion treatment was performed with a homogenizer. Thereafter, using a 0.1 mm zirconia bead and a bead mill (Shinmaru Enterprises Co., Ltd.), circulation treatment was performed at a circumference of 8 m / sec for 2 hours to obtain a MEK solution (dispersion precursor) of a surface-coated pigment. Various MEK solutions were prepared in the same manner except that the ratio of the first resin dispersant to the pigment was changed.

  When this dispersion precursor was dried and observed using a TEM (transmission electron microscope), it was confirmed that a film made of a polyester resin was formed on the surface of the pigment. Although some polyester resins were found to remain without adsorbing on the pigment surface, the exact resin coverage was identified as follows. That is, re-dispersion by centrifugation-decantation and ultrasonic waves (24 KHz 300 W) was repeated. As a result, a pigment dispersion in which excess resin was washed away was produced. The exact resin coating amount was identified by thermal analysis (TG) of the pigment in this dispersion, and is shown in Table 2 below.

  An equivalent amount of a solvent as the present dispersion medium was added to each dispersion precursor. After stirring this for 1 hour, it was heated for 1 hour while stirring at 50 ° C. and 50 mmHg, and further heated for 3 hours at 5 mmHg to remove MEK. In this way, various pigment dispersions as shown in Table 2 below were produced. Examples of the dispersion medium include C3000: Celoxide 3000 (Limonene Dioxide: Daicel Chemical), SR-NPG (Neopentylglycol diglycidyl ether: Sakamoto Yakuhin Kogyo), OXT-221 ([1-ethyl (3-oxetanyl)] methyl. Ether: Toagosei Co., Ltd.), ethyl lactate, DVE-3 (triethylene glycol divinyl ether, ISP Japan), ONB-DVE (oxanorbornane compound having two vinyl ether-containing groups: from Daicel Chemical Industries, Ltd.) Obtained), ISB-DVE (divinyl ether of isosorbitol: obtained from Daicel Chemical Industries, Ltd.), or IBA (isobornyl acrylate, Aldrich) was used.

  In some cases, methyl ethyl ketone is used as it is without converting the solvent.

  The yellow pigment dispersion is described below using any one of Pigment Yellow 150 (manufactured by Clariant), Pigment Yellow 139 (manufactured by Clariant: Graphtol Yellow H2R), and Pigment Yellow 180 (manufactured by Clariant: Toner Yellow HG). Manufactured by two methods.

(Y-1)
First, Pigment Yellow 150 (Clariant), Pigment Yellow 139 (Clariant: Graphtol Yellow H2R), and Pigment Yellow 180 (Clariant: Toner Yellow HG) were prepared. Next, a polyester resin having a terminal amino group as a first resin dispersant (Avicia: Solsperse 32000) and a synergist in an amount of 1/10 (Avicia, Solsperse 22000) with respect to the polyester resin are preliminarily used. It added to MEK as a dispersion medium, and the preliminary dispersion process was performed with the homogenizer. Thereafter, using a 0.1 mm zirconia bead and a bead mill (Shinmaru Enterprises Co., Ltd.), circulation treatment was performed at a circumference of 8 m / sec for 2 hours to obtain a MEK solution (dispersion precursor) of a surface-coated pigment. Various MEK solutions were prepared in the same manner except that the ratio of the first resin dispersant to the pigment was changed.

  When this dispersion precursor was dried and observed using a TEM (transmission electron microscope), it was confirmed that a film made of a polyester resin was formed on the surface of the pigment. Although some polyester resins were found to remain without adsorbing on the pigment surface, the exact resin coverage was identified as follows. That is, re-dispersion by centrifugation-decantation and ultrasonic waves (24 KHz 300 W) was repeated. As a result, a pigment dispersion in which excess resin was washed away was produced. The exact resin coating amount was identified by thermal analysis (TG) of the pigment in this dispersion, and is described in the table below.

An equivalent amount of a solvent as the present dispersion medium was added to each dispersion precursor. After stirring this for 1 hour, it was heated for 1 hour while stirring at 50 ° C. and 50 mmHg, and further heated for 3 hours at 5 mmHg to remove MEK. Thus, various pigment dispersions as shown in the following table were produced. Examples of the dispersion medium include C3000: Celoxide 3000 (Limonene Dioxide: Daicel Chemical), SR-NPG (Neopentylglycol diglycidyl ether: Sakamoto Yakuhin Kogyo), OXT-221 ([1-ethyl (3-oxetanyl)] methyl. Ether: Toagosei Co., Ltd.), ethyl lactate, DVE-3 (triethylene glycol divinyl ether, ISP Japan), ONB-DVE (oxanorbornane compound having two vinyl ether-containing groups: from Daicel Chemical Industries, Ltd.) Obtained) or IBA (isobornyl acrylate, Aldrich).
In some cases, methyl ethyl ketone is used as it is without converting the solvent.

(Y-2)
Permajet Yellow HG (manufactured by Clariant) was added to MEK and pre-dispersed with a homogenizer. Then, using a 0.1 mm zirconia bead and a bead mill, it was circulated for 2 hours at a circumference of 8 m / sec to obtain a MEK solution (dispersion precursor) of a surface-coated pigment.

  When this dispersion precursor was dried and observed using a TEM (transmission electron microscope), it was confirmed that a film made of a vinyl chloride / vinyl acetate copolymer was formed on the surface of the pigment. At this time, since it was observed that a part of the resin was detached from the pigment surface, centrifugation-decantation and redispersion by ultrasonic waves (24 KHz 300 W) were repeated. As a result, surplus resin was washed away, and three types of dispersion precursors with a resin coating amount were obtained. About this dispersion | distribution precursor, the coating amount of each resin calculated | required by the thermal analysis method (TG) was also described in the following table | surface.

  An equivalent amount of a solvent as the present dispersion medium was added to each dispersion precursor. After stirring this for 1 hour, it was heated for 1 hour while stirring at 50 ° C. and 50 mmHg, and further heated for 3 hours at 5 mmHg to remove MEK. Thus, various yellow pigment dispersions as shown in the following table were produced.

  DA or DB was added as a second resin dispersant to the pigment dispersion prepared as described above. Dispersant DA is a polyallylamine compound in which an aromatic polyester having an amine value of 45 is bonded to the amine end, and Dispersant DB is a polyallylamine in which an aliphatic polyester having an amine value of 38 is bonded to the amine end. A compound. Further, the ionic compound was added at a ratio of 2.5% by weight with respect to the dispersion medium. When the concentration of the ionic compound in the dispersion was less than 1% by weight, the effect was small, but good stability was exhibited in the range of 1 to 10% by weight. Therefore, in this example, the ionic compound was blended at a concentration of 2.5 to 3.5% by weight. The ionic compounds used here are the following compounds (C1) to (C4) or (C5) (tetrabutylammonium hexafluorophosphate).

Thereafter, redispersion / dispersion stabilization was performed with a dispersion head (Nippon Seiki: 24 KHz, 600 W) for 1 hour at 40 ° C. or lower while cooling.
As a result of TEM, it was observed that the added second resin dispersant was adsorbed to the pigment together with the first resin dispersant at a ratio of 90% or more. The exact resin coating amount was identified as follows. First, a pigment dispersion in which excess resin was washed away was prepared by repeating centrifugation-decantation and redispersion using ultrasonic waves (24 KHz, 300 W). An accurate resin coating amount was identified by thermal analysis (TG) of the pigment of this dispersion, and is described in Tables 5 to 8 below. For each pigment, a dispersion of Comparative Example (Rf) was prepared by the method of Comparative Example in which the second resin dispersant was not added. Tables 5 and 6 show a blue pigment dispersion and a black pigment dispersion, respectively. Tables 7 and 8 show a yellow pigment dispersion.

  In Tables 5 to 8, the content of the second resin dispersant is% relative to the pigment weight, and the content of the ionic compound indicates% by weight relative to the total solvent amount.

The pigment dispersions shown in Tables 5 to 8 were each allowed to stand at 65 ° C. for 10 days for an acceleration test, and then the particle diameter (d ₁ ) of the pigment particles was examined. It is the Z average particle size obtained by measuring the particle size after dilution with an HPPS measuring instrument (manufactured by Malvern). The particle size after the thermal acceleration test is the particle after the thermal acceleration test after storage at 65 ° C. for 10 days Is the diameter.
The dispersion stability was evaluated as follows from the increase rate (S _A ) of the particle size from the initial particle size (d ₀ ).

(After acceleration test) S _A = ((d ₁ −d ₀ ) / d ₀ )
A: S _A <1.05
B: 1.05 ≦ S _A <1.3
C: S _A ≧ 1.3
The obtained results are summarized in Tables 9 to 12 below. Tables 9 and 10 show the results of the blue pigment dispersion and the black pigment dispersion, respectively. Tables 11 and 12 show the results of the yellow pigment dispersion.

  As shown in Tables 9 to 12, in any of the pigments, the dispersion produced by the method of the comparative example in which the second resin dispersant is not added is inferior in the dispersion stability of the pigment.

  Several types were selected from the dispersions shown in Tables 5 to 8, and the addition amount of the second resin dispersant was changed. The compositions are summarized in Tables 13 to 16 below. Tables 13 and 14 show the blue pigment dispersion and the black pigment dispersion, respectively. Tables 15 and 16 show the yellow pigment dispersion.

  The stability of each dispersion was evaluated by the same method as described above, and the results are summarized in Tables 17 to 20 below. Tables 17 and 18 show the results of the blue pigment dispersion and the black pigment dispersion, respectively. Tables 19 and 20 show the results of the yellow pigment dispersion.

  As shown in Tables 17 to 20, basically, any pigment has a stability of B or more.

  Ink jet inks were prepared according to the formulations shown in Tables 21 to 23 below using some of the dispersions shown in Tables 5 to 8 and 13 to 16. Tables 21, 22, and 23 below show inks using a blue pigment dispersion, a black pigment dispersion, and a yellow pigment dispersion, respectively.

  In the following table, OXT-221 blended as dispersion medium 2 is the above-mentioned oxetane compound (di [1-ethyl (3-oxetanyl)] methyl ether: trade name: OXT221 manufactured by Toagosei Co., Ltd.), and DVE-3 is vinyl ether. Compound (triethylene glycol divinyl ether, ISP Japan), C2021P is an epoxy compound (Daicel Chemical Company, Celoxide 2021P), TMPTA is trimethylolpropane triacrylate (Aldrich, 5% Irgacure 365 (Ciba Geigy) is included), EL is Indicates ethyl lactate. Moreover, as an ionic compound or a photo-acid generator, the same thing as a dispersion was used, and it adjusted so that it might become the density | concentration with respect to all the solvents in a table | surface.

  Furthermore, an inkjet ink (LL-Rf) was prepared by the method of the comparative example using the dispersions of the comparative examples described in Tables 5, 6, and 8.

  The amount of photoacid generator in Table 22 includes dibutoxyanthracene added as a sensitizer, and this sensitizer was used in an amount of 30% by weight of the photoacid generator.

Next, the performance test of each inkjet ink was performed using the inkjet recording apparatus 1 shown in FIG.
Ink-jet inks prepared with the formulations shown in Tables 21 to 23 were prepared by filtration through a 1 micron membrane filter. A normal glossy paper is used as the recording medium 2, an ultrahigh pressure mercury lamp with an output of 230 W is used as the light source 5, and an exposure amount is 500 mJ / cm ² (however, LL-C5, LL-B5, and LL). -Y5 was not irradiated with light). The four temperatures of the recording head were kept at 45 ° C., and an infrared ceramic heater with an output of 600 W was used as the heating mechanism 6.

The formed ink layer was evaluated for pencil hardness, printing stability, solvent resistance, and printing image quality as follows.
The printing stability is indicated by the discharge error frequency (number of times) per 24 hours.
The solvent resistance was evaluated as follows by examining resistance to three kinds of solvents, water, ethanol, and acetone. Those having resistance only to water were set to “1”, and those having resistance to water and ethanol were set to “2”. Those that are resistant to water, ethanol and acetone are all designated as “3”.
The image quality was judged by visual observation, and the situation was noted for those with problems. In addition, some disturbances (such as misdirection shots) of the image are slightly observed, but if the details are not examined in detail, the level at which the miss shot is not noticed is “good”, and the case where no error shot is observed is “excellent”. did. If the misdirection shot is conspicuous, but it is at a level that does not hinder the interpretation of the print, it was determined as “OK”.

  The obtained results are summarized in the following Tables 24 to 26 together with the acceleration test evaluation of each ink. Table 24 below shows the results for the blue ink. In addition, since what uses EL as a solvent is not a curable ink, hardness and solvent tolerance were not measured.

As shown in Table 24 above, all the blue inks produced by the methods of the examples have stable acceleration tests and printing, and the images obtained have excellent image quality. On the other hand, it can be seen that the ink produced by the method of the comparative example has an increased particle size and lacks ejection stability, and the image quality is also mediocre with some misdirection observed.
From the above results, it can be seen that when the blue pigment is contained in a proportion of 2 to 30 parts by weight with respect to the total weight of the dispersion medium, the color and dispersion stability are good. It can also be seen that the optimum resin amount of the first resin dispersant is 10% or more and 30% or less, and the addition amount of the second resin dispersant is 5% or more and 30% or less with respect to the pigment weight. When the content of the resin dispersant is too small, the color sensation and dispersion stability are poor. On the other hand, when the content is too large, problems such as viscosity and dispersion stability increase.

  Table 25 below shows the results for black ink.

As shown in Table 25 above, all the black inks produced by the methods of the examples have stable acceleration tests and printing, and the image quality obtained is excellent. On the other hand, it can be seen that the ink produced by the method of the comparative example has an increased particle size and lacks ejection stability, and the image quality is also mediocre with some misdirection observed.
From the above results, it can be seen that when the black pigment is contained in a proportion of 2 to 30 parts by weight with respect to the total weight of the dispersion medium, the color and dispersion stability are good. Further, it is understood that the optimum resin amount of the first resin dispersant is 10% or more and 30% or less, and the addition amount of the second resin dispersant is 5% or more and 30% or less with respect to the pigment weight. . When the content of the resin dispersant is too small, the color sensation and dispersion stability are poor. On the other hand, when the content is too large, problems such as viscosity and dispersion stability increase.

  Table 26 below shows the results for yellow ink.

As shown in Table 26 above, all the yellow inks produced by the method of the examples have stable acceleration tests and printing, and the image quality obtained is excellent. On the other hand, it can be seen that the ink produced by the method of the comparative example lacks ejection stability, and the image quality is mediocre with some misdirection observed.
From the above results, it can be seen that when the yellow pigment is contained in a proportion of 2 to 30 parts by weight with respect to the total weight of the dispersion medium, the color and dispersion stability are good. Further, it is understood that the optimum resin amount of the first resin dispersant is 10% or more and 60% or less, and the addition amount of the second resin dispersant is 1% or more and 30% or less with respect to the pigment weight. . When the content of the resin dispersant is too small, the color sensation and dispersion stability are poor. On the other hand, when the content is too large, problems such as viscosity and dispersion stability increase.

  In any of the pigments, it was confirmed that the ink jet ink produced by the comparative method in which the pigment was directly dispersed in the dispersion medium without using the second resin dispersant increased in size by an acceleration test. It was. As a result, it was confirmed that the number of errors in ejection was nearly one digit higher than that of the ink of the example.

  Next, several types of dispersions were produced using dispersion media having different viscosities, and the influence of the viscosity of the solvent used as the dispersion medium was examined. Solvents include SR-NPG, SR-16H (1,6-hexanediol diglycidyl ether: Sakamoto Yakuhin Kogyo), SR-TPG (tripropylene glycol diglycidyl ether: Sakamoto Yakuhin Kogyo), SR-4PG (polypropylene glycol di). Glycidyl ether: Sakamoto Pharmaceutical Co., Ltd.) and SR-8EGS (polyethylene glycol diglycidyl ether: Sakamoto Pharmaceutical Co., Ltd.) were prepared. Each of these dispersion media has a boiling point of 150 ° C. or more at 1 atmosphere.

  Pigment Yellow 139 was used as the pigment, and the concentration was 25% based on the total solvent weight. Also, five types of yellow pigment dispersions were prepared by the same method as in the case of I-Y1 (25) 15s-b described above except that the dispersant resin content was 20% with respect to the pigment weight. did.

  A pigment dispersion was prepared by adding DA as the second resin dispersant and (C2) as the ionic compound to the obtained pigment dispersion. The DA content was 20%, and the (C2) content was 3.75% by weight with respect to the solvent. Finally, C3000 was added as a diluent solvent (dispersion medium 2) to produce an inkjet ink. In the ink, the pigment concentration in the ink was 4%, and the ratio of the dispersion medium 1 and the dispersion medium 2 was 1: 1 by weight.

  The viscosity of the obtained pigment dispersion and ink was measured with an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.) and is shown in Table 27 below together with the viscosity of the dispersion medium. Further, each ink-jet ink was subjected to a performance test by the ink-jet recording apparatus shown in FIG. 1 to evaluate the printing stability and image quality of the ink. The obtained results are also shown in Table 27 below.

  From the results shown in Table 27, it was found that the ink using the dispersion medium having a viscosity of 30 mPa · s (25 ° C.) or less is excellent in printing stability and printing image. Further, the ink produced using a dispersion medium having a viscosity exceeding 30 mPa · s has a high frequency of ejection errors, and misdirection is also observed in the image quality. From this, it is understood that a dispersion medium having a viscosity of 30 mPa · sec or less is more preferably used as the dispersion medium used for the pigment dispersion.

1 is a schematic view of an ink jet recording apparatus using an ink jet ink manufactured by a method according to an embodiment of the present invention.

Explanation of symbols

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

Claims (17)

A method for producing a powder dispersion containing a powder having an average particle size of 300 nm or less,
Adding powder to the dispersion medium in an amount of 2 to 60 parts by weight;
Adding a first resin dispersant to the dispersion medium in an amount of 1% to 30% with respect to the weight of the powder, and dispersing and coating the powder with the resin;
A step of adding 2% to 30% of a second resin dispersant containing a resin having a basic terminal to further disperse the resin-coated powder, and the second resin dispersant. A method for producing a powder dispersion, comprising adding 0.01 parts by weight or more and 40 parts by weight or less of an onium salt compound to the dispersion medium to which is added. A method for producing a powder dispersion containing a powder having an average particle size of 300 nm or less,
Adding powder to the low boiling point organic solvent in an amount of 2 parts by weight or more and 60 parts by weight or less;
A step of adding a first resin dispersant to the low-boiling organic solvent in an amount of 1% or more and 30% or less with respect to the weight of the powder, and dispersing and coating the powder with a resin to obtain a dispersion precursor. ,
Adding a dispersion medium containing a polymerizable compound to the dispersion precursor, and removing the low-boiling organic solvent;
Adding a second resin dispersant containing a resin having a basic terminal to the dispersion medium in an amount of 2% to 30% based on the weight of the powder to further disperse the resin-coated powder; and A method for producing a powder dispersion, comprising the step of adding 0.01 to 40 parts by weight of an onium salt compound to the dispersion medium to which the second resin dispersant is added. A method for producing a pigment dispersion containing a pigment having an average particle size of 200 nm or less,
Adding a pigment to the dispersion medium in an amount of 2 to 30 parts by weight;
Adding a first resin dispersant to the dispersion medium in an amount of 10% or more and 60% or less based on the weight of the pigment, and dispersing and coating the pigment with a resin;
A step of adding a second resin dispersant containing a resin having a basic end to 1% to 30% of the pigment weight to further disperse the resin-coated pigment; and the second resin dispersant added. A method for producing a pigment dispersion, comprising the step of adding 0.01 to 20 parts by weight of an onium salt compound to the dispersion medium. A method for producing a pigment dispersion containing a pigment having an average particle size of 200 nm or less,
Adding a pigment to the low boiling point organic solvent in an amount of 2 to 30 parts by weight;
Adding a first resin dispersant to the low-boiling organic solvent in an amount of 10% or more and 60% or less based on the weight of the pigment, and dispersing and coating the pigment with a resin to obtain a dispersion precursor;
Adding a dispersion medium containing a polymerizable compound to the dispersion precursor, and removing the low-boiling organic solvent;
Adding a second resin dispersant containing a resin having a basic terminal to the dispersion medium in an amount of 1% to 30% based on the pigment weight to further disperse the resin-coated pigment; and A method for producing a pigment dispersion, comprising adding 0.01 parts by weight or more and 20 parts by weight or less of an onium salt compound to a dispersion medium to which the resin dispersant 2 is added. The second resinous dispersing agent, the production method of a pigment dispersion according to claim 3 or 4, wherein that you have attracted to the first dispersant. The method for producing a pigment dispersion according to any one of claims 3 to 5, wherein the second resin dispersant adsorbs and / or ion-bonds a part of the onium salt compound . The pigment is a phthalocyanine pigment, the amount of the first resin dispersant is 10% to 30% with respect to the weight of the pigment, and the amount of the second resin dispersant is the pigment the manufacturing method of a pigment dispersion according to any one of claims 3 to 6, the said der Rukoto 30% less than 5% by weight. The pigment is a carbon black pigment, the amount of the first resin dispersant is 10% or more and 30% or less with respect to the weight of the pigment, and the amount of the second resin dispersant is The method for producing a pigment dispersion according to any one of claims 3 to 6 , wherein the content is 5% or more and 30% or less with respect to the weight of the pigment. The pigment manufacturing method of a pigment dispersion according to any one of claims 3 to 6, characterized in that • The amber pigments der. Wherein the pigment is a manufacturing method of a pigment dispersion according to claim 9, wherein PY139 or PY150 der Rukoto. The method for producing a pigment dispersion according to any one of claims 3 to 10 , wherein the dispersion medium contains a cationically polymerizable compound . The dispersion medium is a 300 mPa · s or less in viscosity at 25 ° C., the pigment dispersion according to claim 11, wherein to Rukoto main component a compound having the property of not lower than the boiling point 0.99 ° C. at one atmosphere pressure Production method. A method for producing an inkjet ink containing a pigment having an average particle size of 200 nm or less,
Adding a pigment to the dispersion medium in an amount of 2 to 30 parts by weight;
Adding a first resin dispersant to the dispersion medium in an amount of 10% or more and 60% or less based on the weight of the pigment, and dispersing and coating the pigment with a resin;
A step of further dispersing the resin-coated pigment by adding a second resin dispersant containing a resin having a basic end to 1% to 30% based on the pigment weight; and
Adding 0.01 to 20 parts by weight of an onium salt compound to the dispersion medium to which the second resin dispersant is added
A method for producing an inkjet ink, comprising : A method for producing an inkjet ink containing a pigment having an average particle size of 200 nm or less,
Adding a pigment to the low boiling point organic solvent in an amount of 2 to 30 parts by weight;
Wherein the low-boiling organic solvent, the first resinous dispersing agent, the pigment coated with resin-dispersed in an amount of 60% or less than 10% by weight of the pigment, Ru obtain a dispersion precursor step,
Adding a dispersion medium containing a polymerizable compound to the dispersion precursor, and removing the low-boiling organic solvent;
Adding a second resin dispersant containing a resin having a basic terminal to the dispersion medium in an amount of 1% to 30% based on the pigment weight to further disperse the resin-coated pigment; and A method for producing an ink-jet ink comprising the step of adding 0.01 parts by weight or more and 20 parts by weight or less of an onium salt compound to a dispersion medium to which the resin dispersant 2 is added. The method for producing an inkjet ink according to claim 13 or 14, wherein the dispersion medium contains a cationically polymerizable compound . The method for producing an inkjet ink according to claim 15 , wherein the cationically polymerizable compound contains a vinyl ether compound . The method for producing an inkjet ink according to claim 16, wherein the vinyl ether compound includes a cyclic ether compound having a substituent containing a vinyl ether structure .

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