JP2009172971A - Inkjet recording ink set, inkjet recording method and recorded matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording ink set which can settle considerations such as coloring nature of paper and gloss irregularities of glossy paper. <P>SOLUTION: This inkjet recording ink set is composed of a clear ink which contains a polymer particulate and a water-insoluble organic compound, and contains no coloring matter, and a color ink which contains a pigment as a coloring matter, a polymer particulate and the water-insoluble organic compound for dispersing the pigment and does not react with the clear ink. The polymer particulate is a water-insoluble polymer particle which can be obtained by copolymerizing a monomer mixture containing (1) a salt forming group-containing monomer, (2) a macromer and/or (3) a hydrophobic monomer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink set for ink jet recording, an ink jet recording method, and a recorded matter, and more specifically, an ink set for ink jet recording, an ink jet recording method, and a recorded matter that eliminate color development on plain paper and gloss unevenness on glossy paper. About.

  The ink jet recording method is a printing method in which printing is performed by ejecting small droplets of ink from a fine nozzle head so that the ink droplets are ejected and adhered to a recording medium such as paper. This method is characterized in that a high-resolution and high-quality image can be printed at a high speed with a relatively inexpensive apparatus. Ink jet recording apparatuses using this method are widely accepted commercially due to good print quality, low cost, relatively quiet operation and graphic forming ability. Among them, thermal (bubble jet (registered trademark)) and piezoelectric drop-on-demand printers have been particularly successful in the market and have been widely used as printers for personal computers in offices and homes.

  Conventionally, in such an ink jet recording method, a technique for achieving high-performance print image quality using clear ink and color ink has been proposed. For example, techniques described in Patent Documents 1 to 7 and the like can be mentioned.

  Among them, Patent Document 1 aims to easily provide a recorded material that has excellent weather resistance and greatly reduced gloss unevenness without increasing costs, changing the ink jet recording apparatus, or increasing the size. An inkjet recording method for recording on a recording medium by discharging a pigment ink (color ink) composition and a clear ink composition containing a resin component, wherein the gloss on the entire recording surface of the recording medium after recording is substantially An inkjet recording method is disclosed in which the discharge amount of the pigment ink composition and / or the discharge amount of the clear ink composition is adjusted so as to be uniform.

  In Patent Document 2, for the purpose of reducing graininess, a diluted ink (clear ink) containing at least water and a water-soluble organic solvent and substantially free of a colorant, and at least a colorant, water and a water-soluble substance are used. Using a water-based ink set for inkjet recording, which is composed of one or more kinds of colored inks (color inks) containing an organic solvent, and the dynamic surface tension of the diluted ink is higher than the dynamic surface tension of the colored ink. An inkjet recording method characterized by overprinting with colored ink, and further, an inkjet recording method for overprinting colored ink on a portion where diluted ink is recorded are disclosed.

  Further, in Patent Document 3, for the purpose of obtaining a multi-order color excellent in glossiness and image clarity and composite black, an ink set comprising two or more different color inks, the ink, An ink set for inkjet recording, which is an ink containing a water-insoluble organic compound, polymer particles, and a colorant, is disclosed.

  However, with the ink sets that have been used so far, the improvement in color development of printed images on plain paper and the reduction in uneven glossiness of printed images on glossy paper have not been satisfied at the same time. Therefore, a technology capable of eliminating the color developability of plain paper and the gloss unevenness of glossy paper has been desired.

Table 2002/088786 JP 2006-232933 A JP 2006-316246 A Japanese Patent No. 3912212 JP 2006-272934 A JP 2003-286428 A JP 2005-532924 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink set for ink-jet recording that eliminates color developability on plain paper and gloss unevenness on glossy paper.

  Acquired the knowledge that an ink set for ink-jet recording comprising a clear ink having a specific polymer together with a water-insoluble organic compound, and a color ink containing a pigment in addition to these, can achieve the above-mentioned object, and the present invention It came.

That is, the present invention has the following configuration.
1. A clear ink containing fine polymer particles and a water-insoluble organic compound and containing no colorant, a pigment as a colorant, a fine polymer particle for dispersing the pigment and a water-insoluble organic compound, and reacting with the clear ink An ink set for ink-jet recording comprising:
An ink set for ink jet recording, wherein the polymer fine particles are water-insoluble polymer particles obtained by copolymerizing a monomer mixture containing 1) a salt-forming group-containing monomer, 2) a macromer and / or 3) a hydrophobic monomer.

2. The water-insoluble organic compound is i) an ester or ether compound having two or more ester or ether bonds in the molecule, and / or ii) one or more ester or ether bonds in the molecule, a carboxy group, 2. The ink set for inkjet recording according to 1 above, which is an ester or ether compound having at least one functional group selected from the group consisting of a sulfonic acid group, a phosphoric acid residue, a carbonyl group, an epoxy group and a hydroxyl group. .

3. 3. The ink set for inkjet recording according to 1 or 2, wherein the color ink is at least one ink selected from magenta ink, yellow ink, and cyan ink.

4). The clear ink and the color ink both contain trialkanolamine, and the content of trialkanolamine in the clear ink is larger than the content of trialkanolamine in the color ink, The ink set for inkjet recording as described in 2.

5). 5. An ink jet recording method for forming a print image by ejecting droplets of the clear ink and the color ink in the ink set for ink jet recording according to any one of 1 to 4 above onto a recording medium.

6). A recorded matter printed by the ink set for inkjet recording according to any one of 1 to 4 above.

  According to the present invention, it is possible to provide an ink set for ink-jet recording, an ink-jet recording method, and a recorded matter that eliminate color development on plain paper and gloss unevenness on glossy paper.

Next, the present invention will be described in more detail based on preferred embodiments thereof.
As described above, the ink set for inkjet recording of the present invention includes a clear ink containing fine polymer particles and a water-insoluble organic compound, and does not contain a colorant, a pigment as a colorant, and a polymer for dispersing the pigment. An ink set for ink-jet recording comprising a fine particle and a color ink that contains a pigment as a water-insoluble organic compound and does not react with the clear ink, wherein the polymer fine particle comprises 1) a salt-forming group-containing monomer, and 2) Macromer and / or 3) Water-insoluble polymer particles obtained by copolymerization of a monomer mixture containing a hydrophobic monomer.

Since the present invention is configured as described above, it is possible to eliminate color development on plain paper and gloss unevenness on glossy paper.
In this specification, gloss unevenness means that when pigment ink is printed on a glossy recording medium, there is a large difference in glossiness between a portion where the amount of pigment ink applied per unit area is large and a portion where the amount is small. It means a state of feeling uncomfortable visually. Actually, it means a state in which a difference in 20 ° specular glossiness of a printed image formed with the color ink composition and / or the clear ink composition is large. The 20 ° specular gloss is measured by a gloss meter.
Further, in this specification, the ink ejection amount is defined by (the number of dots applied per unit area) × (weight per dot).

  As the pigment contained in the color ink, an inorganic pigment and an organic pigment can be used, and each can be used alone or in a mixture of plural kinds. As the inorganic pigment, for example, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. Examples of the organic pigment include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments), and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, Quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, or quinofullerone pigments), dye chelates (for example, basic dye-type chelates or acidic dye-type chelates), nitro pigments, nitroso pigments, or aniline black Can be used.

  Further specific examples of the pigment will be described below. First, preferable pigments for the yellow ink composition include, for example, 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 14, 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 109, C.I. I. Pigment Yellow 110, C.I. I. Pigment Yellow 114, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 129, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 150, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 154, C.I. I. Pigment Yellow 155, C.I. I. Pigment Yellow 180, C.I. I. Pigment Yellow 185 and the like. Among these, pigments that can be particularly preferably used include C.I. I. Pigment Yellow 74, 110, 128, and the like.

  Examples of preferable pigments for the magenta ink composition include C.I. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 112, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 168, C.I. I. Pigment Red 184, C.I. I. Pigment Red 202, C.I. I. Pigment Violet 19 and the like. Among these, C.I. I. Pigment Red 122, C.I. I. Pigment Vioret 19 and the like.

  Preferred pigments for the cyan ink composition include C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4, C.I. I. Pigment Blue 15:34, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 60, C.I. I. Vat Blue 4, C.I. I. Vat Blue 60 can be mentioned, and among these, C.I. I. Pigment Blue 15: 3, C.I. I. And CI Pigment Blue 15: 4.

  A preferred pigment for the black ink composition is carbon black. 2300, no. 900, MCF88, No. 33, no. 40, no. 52, MA7, MA8, MA100, no. Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc. manufactured by Columbia, such as 2200B, Regal 400R, Regal 400R, Regal 1660R, Mull 1, Monch 800, MonMarch 800, Monarch 800, Monarch 800, Monarch 800, Monarch 800 Color Black FW1, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black FW200, Color Black FW200, Color Black FW200, Color Black FW200, Color Black FW200, Color Black FW200, Color Black FW200, Color Black FW200 , Mention may be made of Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, the Special Black 4 and the like.

The polymer fine particles used in the color ink and the clear ink are water-insoluble polymer particles obtained by copolymerizing a monomer mixture containing 1) a salt-forming group-containing monomer, 2) a macromer and / or 3) a hydrophobic monomer. This water-insoluble polymer has 1) a structural unit derived from the component, 2) a structural unit derived from the component, and / or 3) a structural unit derived from the component.
In the present invention, the polymer particles are used to easily contain a water-insoluble organic compound, which will be described later, and to improve printing density, glossiness, and image clarity by interacting with the polymer particles.

The salt-forming group-containing monomer 1) is used from the viewpoint of enhancing the dispersion stability of the resulting dispersion. Examples of the salt-forming group include a carboxy group, a sulfonic acid group, a phosphoric acid group, an amino group, and an ammonium group.
Examples of the salt-forming group-containing monomer include a cationic monomer and an anionic monomer. Examples thereof include those described in JP-A-9-286939, page 5, column 7, line 24 to column 8, line 29.

  Representative examples of the cationic monomer include unsaturated amine-containing monomers and unsaturated ammonium salt-containing monomers. Among these, N, N-dimethylaminoethyl (meth) acrylate, N- (N ′, N′-dimethylaminopropyl) (meth) acrylamide and vinylpyrrolidone are preferable.

Representative examples of anionic monomers include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers, and the like.
Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid. Examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconic acid ester, and the like. Examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxy Examples thereof include ethyl phosphate.
Among the anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid and methacrylic acid are more preferable from the viewpoints of dispersion stability and ejection stability.

The macromer of 2) is used from the viewpoint of enhancing the dispersion stability of the polymer particles, particularly when the polymer particles contain a colorant. The macromer includes a macromer which is a monomer having a polymerizable unsaturated group having a number average molecular weight of 500 to 100,000, preferably 1,000 to 10,000. 2) The number average molecular weight of the macromer is measured using polystyrene as a standard substance by gel chromatography using 1 mmol / L dodecyldimethylamine-containing chloroform as a solvent.
2) Among the macromers, from the viewpoint of dispersion stability of polymer particles and the like, styrene-based macromers and aromatic group-containing (meth) acrylate-based macromers having a polymerizable functional group at one end are preferable.

  Examples of the styrenic macromer include a styrene monomer homopolymer or a copolymer of a styrene monomer and another monomer. Examples of the styrene monomer include styrene, 2-methylstyrene, vinyl toluene, ethyl vinyl benzene, vinyl naphthalene, chlorostyrene, and the like.

Examples of the aromatic group-containing (meth) acrylate-based macromer include a homopolymer of an aromatic group-containing (meth) acrylate or a copolymer thereof with another monomer. As an aromatic group-containing (meth) acrylate, an arylalkyl having 7 to 22 carbon atoms, preferably 7 to 18 carbon atoms, more preferably 7 to 12 carbon atoms, which may have a substituent containing a hetero atom. (Meth) acrylate having an aryl group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, which may have a group or a substituent containing a hetero atom In addition, examples of the substituent containing a hetero atom include a halogen atom, an ester group, an ether group, and a hydroxy group. Examples include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, and benzyl (meth) acrylate is particularly preferable.
The polymerizable functional group present at one end of the macromer is preferably an acryloyloxy group or a methacryloyloxy group, and the other monomer to be copolymerized is preferably acrylonitrile.
The content of the styrene monomer in the styrene macromer or the aromatic group-containing (meth) acrylate in the aromatic group-containing (meth) acrylate macromer is preferably 50% by weight from the viewpoint of increasing the affinity with the pigment. Above, more preferably 70% by weight or more.

  2) Styrenic macromers that are commercially available as components include, for example, trade names of Toa Gosei Co., Ltd., AS-6 (S), AN-6 (S), HS-6 (S), and the like. .

  3) Hydrophobic monomers are used from the viewpoint of improving printing density, glossiness, and image clarity. Examples of the hydrophobic monomer include alkyl (meth) acrylates and aromatic group-containing monomers.

As the alkyl (meth) acrylate, those having an alkyl group having 1 to 22 carbon atoms, preferably 6 to 18 carbon atoms are preferable. For example, methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meta) ) Acrylate, (iso or tertiary) butyl (meth) acrylate, (iso) amyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) Examples include decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, and (iso) stearyl (meth) acrylate.
In the present specification, “(iso or tertiary)” and “(iso)” mean both the case where these groups are present and the case where these groups are not present. Indicates. “(Meth) acrylate” indicates acrylate, methacrylate, or both.

  As the aromatic group-containing monomer, a vinyl monomer having an aromatic group having 6 to 22 carbon atoms, preferably 6 to 12 carbon atoms, which may have a substituent containing a hetero atom, is preferable. Examples thereof include styrene monomers (3-1 component) and the above-mentioned aromatic group-containing (meth) acrylate (3-2 component). The above-mentioned thing is mentioned as a substituent containing a hetero atom.

  Among the components 3), styrenic monomers (3-1 components) are preferable from the viewpoint of improving glossiness and printing density, and examples of the styrenic monomers include those described above, and styrene and 2-methylstyrene are particularly preferable. . The content of the component (3-1) in the component 3) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving printing density and glossiness.

  Examples of the aromatic group-containing (meth) acrylate (3-2) component include those described above, and benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and the like are preferable. The content of the component (3-2) in the component (3) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving glossiness. Moreover, it is also preferable to use together (3-1) component and (3-2) component.

The monomer mixture may further contain 4) a hydroxyl group-containing monomer (hereinafter sometimes referred to as “4) component”). 4) A hydroxyl group-containing monomer exhibits an excellent effect of enhancing dispersion stability.
4) As components, for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, polyethylene glycol (n = 2 to 30, n represents the average number of moles of oxyalkylene group added. .) (Meth) acrylate, polypropylene glycol (n = 2 to 30) (meth) acrylate, poly (ethylene glycol (n = 1-15) / propylene glycol (n = 1-15)) (meth) acrylate, and the like. It is done. Among these, 2-hydroxyethyl (meth) acrylate, polyethylene glycol monomethacrylate, and polypropylene glycol methacrylate are preferable.

The monomer mixture may further contain 5) a monomer represented by the following formula (11) (hereinafter also referred to as “5) component”).
^{_{CH 2 = C (R 7)}} COO (R 8 O) p R 9 (11)
Wherein R ⁷ is a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ⁸ is a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, and R ⁹ is , A monovalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, p means an average added mole number, and represents a number of 1 to 60, preferably 1 to 30. )
5) The component exhibits an excellent effect of improving the printing density, glossiness, and image clarity of the ink.
In the formula (11), examples of the hetero atom include a nitrogen atom, an oxygen atom, a halogen atom, and a sulfur atom.
Preferable examples of R ⁷ include a methyl group, an ethyl group, and an (iso) propyl group.
Preferable examples of the R ⁸ O group include an oxyethylene group, an oxy (iso) propylene group, an oxytetramethylene group, an oxyheptamethylene group, an oxyhexamethylene group, and a combination of two or more of these oxyalkylenes having 2 carbon atoms. -7 oxyalkylene groups.
Preferable examples of R ⁹ include aliphatic alkyl groups having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, alkyl groups having 7 to 30 carbon atoms having an aromatic ring, and 4 to 30 carbon atoms having a heterocyclic ring. Of the alkyl group.

  5) As specific examples of the component, methoxypolyethylene glycol (1-30: the value of p in formula (11) is shown. The same applies hereinafter) (meth) acrylate, methoxypolytetramethylene glycol (1-30) (meta ) Acrylate, ethoxy polyethylene glycol (1-30) (meth) acrylate, octoxy polyethylene glycol (1-30) (meth) acrylate, polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether, (iso) propoxy Polyethylene glycol (1-30) (meth) acrylate, butoxypolyethylene glycol (1-30) (meth) acrylate, methoxypolypropylene glycol (1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol) Polymerization) (1 to 30, ethylene glycol therein: 1-29) (meth) acrylate. Among these, octoxypolyethylene glycol (1-30) (meth) acrylate and polyethylene glycol (1-30) (meth) acrylate 2-ethylhexyl ether are preferable.

  Specific examples of commercially available 4) and 5) components include Shin-Nakamura Chemical Co., Ltd. polyfunctional acrylate monomer (NK ester) M-40G, 90G, and 230G, and Blend of Nippon Oil & Fat Co., Ltd. Mer series, PE-90, 200, 350, PME-100, 200, 400, 1000, PP-500, 800, 1000, AP-150, 400, 550, 800, 50 PEP -300, 50POEP-800B etc. are mentioned.

The above 4) to 5) components can be used alone or in admixture of two or more.
Composition derived from components 1) to 5) in the monomer mixture of the above 1) to 5) in the production of the water-insoluble polymer (content as an unneutralized amount; the same shall apply hereinafter) The content of the unit is as follows.
1) The content of the component is preferably 2 to 40% by weight, more preferably 2 to 30% by weight, and particularly preferably 3 to 20% by weight from the viewpoint of dispersion stability of the resulting dispersion.
2) The content of the component is preferably 1 to 25% by weight, more preferably 5 to 20% by weight, particularly from the viewpoint of enhancing the interaction with the colorant.
3) The content of the component is preferably 5 to 98% by weight, more preferably 10 to 60% by weight from the viewpoints of glossiness and image clarity.

  The weight ratio (1) / [2) +3)]) of the components 1), 2) and 3) in the water-insoluble polymer is preferably 0.01 to 1, more preferably from the viewpoint of glossiness and image clarity. It is 0.02-0.67, More preferably, it is 0.03-0.50.

4) The content of the component is preferably 5 to 40% by weight, more preferably 7 to 20% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
5) The content of the component is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
The total content of [1) component + 4 component] in the monomer mixture is preferably 6 to 60% by weight, more preferably 10 to 50% by weight, from the viewpoint of dispersion stability of the resulting dispersion. The total content of [1) component + 5) component] is preferably 6 to 75% by weight, more preferably 13 to 50% by weight, from the viewpoint of dispersion stability of the resulting dispersion. The total content of [1) component + 4) component + 5) component] is preferably 6 to 60% by weight, more preferably 7 to 50% by weight, from the viewpoint of dispersion stability of the resulting dispersion.

(Manufacture of polymers)
The polymer used in the present invention is produced by copolymerizing a monomer mixture by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable.
The solvent used in the solution polymerization method is not particularly limited, but a polar organic solvent is preferable. When the polar organic solvent is miscible with water, it can be used by mixing with water. Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and the like. Among these, methanol, ethanol, acetone, methyl ethyl ketone, or a mixed solvent of one or more of these and water is preferable.

  In the polymerization, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), t-butyl peroxyoctate, dibenzoyl oxide, etc. Known radical polymerization initiators such as organic peroxides can be used. The amount of the radical polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture. In the polymerization, a known polymerization chain transfer agent such as mercaptans such as octyl mercaptan and 2-mercaptoethanol and thiuram disulfide may be further added.

Since the polymerization conditions of the monomer mixture vary depending on the type of radical polymerization initiator, monomer, and solvent used, it cannot be determined unconditionally. Usually, the polymerization temperature is preferably 30 to 100 ° C, more preferably 50 to 80 ° C, and the polymerization time is preferably 1 to 20 hours. The polymerization atmosphere is preferably a nitrogen gas atmosphere or an inert gas atmosphere such as argon.
After completion of the polymerization reaction, the produced polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained polymer can be purified by repeating reprecipitation or by removing unreacted monomers and the like by membrane separation, chromatographic method, extraction method and the like.

The weight average molecular weight of the polymer obtained as described above is preferably from 5,000 to 500,000, more preferably from 10,000 to 400,000, from the viewpoints of dispersion stability of the colorant, water resistance and dischargeability. 000 to 300,000 is particularly preferred.
In addition, the weight average molecular weight of a polymer is measured using polystyrene as a standard substance by gel chromatography using dimethylformamide containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent.

  The water-insoluble polymer used in the present invention is 1) neutralized with a neutralizing agent when it has a salt-forming group derived from a salt-forming group-containing monomer. As the neutralizing agent, an acid or a base can be used depending on the type of the salt-forming group in the polymer. For example, hydrochloric acid, acetic acid, propionic acid, phosphoric acid, sulfuric acid, lactic acid, succinic acid, glycolic acid, gluconic acid, glyceric acid and other acids, lithium hydroxide, sodium hydroxide, potassium hydroxide ammonia, methylamine, dimethyl Examples include bases such as amine, trimethylamine, ethylamine, diethylamine, trimethylamine, triethanolamine, and tributylamine.

The degree of neutralization of the salt-forming group is preferably 10 to 200%, more preferably 20 to 150%, and particularly preferably 50 to 150%.
Here, the degree of neutralization can be determined by the following formula when the salt-forming group is an anionic group.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [acid value of polymer (KOH mg / g) × polymer weight (g) / (56 × 1000)]} × 100
When the salt-forming group is a cationic group, the degree of neutralization can be determined by the following formula.
[[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [amine value of polymer (HCL mg / g) × weight of polymer (g) / (36.5 × 1000)]] × 100
The acid value and amine value can be calculated from the structural unit of the polymer. Alternatively, it can also be determined by a method in which a polymer is dissolved in a suitable solvent (for example, methyl ethyl ketone) and titrated.

  The water-insoluble organic compound used in the color ink and the clear ink is a compound that imparts plasticity that can be contained at least in part in the polymer fine particles to improve the flexibility of the polymer fine particles. The water-insoluble organic compound imparts flexibility to the polymer particles, so that the polymer particles in one ink ejected from the sol of the ink jet recording apparatus are easily fused with the polymer particles of the other ink on the recording paper. Therefore, it is considered that the glossiness and image clarity of the obtained multi-colored color or composite black printed matter (including printed matter, hereinafter the same) are improved.

The water-insoluble organic compound preferably has a molecular weight of 100 to 2,000, more preferably a molecular weight of 100 to 1,000, from the viewpoint of the glossiness of the printed matter.
The amount of water-soluble organic compound dissolved in 100 g of water (20 ° C.) is 5 g or less, preferably 3 g or less, more preferably 1 g or less.

The water-insoluble organic compound is preferably an ester compound, an ether compound, or a sulfonic acid amide compound so that the water-insoluble organic compound can be easily contained in the polymer particles. I) An ester or an ester having two or more ester or ether bonds in the molecule Ether compound and / or ii) one or more selected from the group consisting of one or more ester or ether bonds in the molecule and a carboxy group, sulfonic acid group, phosphoric acid residue, carbonyl group, epoxy group and hydroxyl group An ester or ether compound having at least one functional group is more preferable. i) The number of ester or ether bonds of the compound is preferably 2 to 3. ii) The number of ester or ether bonds of the compound is preferably 1 to 3. The number of functional groups is preferably 1 to 3. A phosphoric acid residue means the remaining phosphoric acid group in which a part of phosphoric acid was esterified or etherified.
Among these, an ester obtained from a monovalent carboxylic acid or a salt thereof and a polyhydric alcohol, an ester obtained from a polyvalent acid (polycarboxylic acid, phosphoric acid) or a salt thereof and a monohydric alcohol, or a polyhydric alcohol Ether compounds are preferred, and it is more preferred to have two aliphatic or aromatic carboxylic acid ester groups or three phosphoric acid ester groups. Examples of the salt include alkali metal salts, alkanolamine salts, ammonium salts and the like.

  As the monovalent carboxylic acid, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, Linear aliphatic carboxylic acids such as palmitic acid, branched aliphatic carboxylic acids such as pivalic acid, unsaturated aliphatic carboxylic acids such as acrylic acid and methacrylic acid), and aromatic carboxylic acids having 6 to 12 carbon atoms (for example, As the polyvalent acid, an aliphatic carboxylic acid having 2 to 12 carbon atoms such as maleic acid, fumaric acid, itaconic acid, succinic acid, adipic acid and sebacic acid; phthalic acid and trimellitic acid C6-C12 aromatic carboxylic acid, phosphoric acid, etc. are mentioned.

  The monohydric alcohol is a linear or branched aliphatic alcohol having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, ethyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, decyl alcohol, dodecyl alcohol). , Aromatic alcohols having 6 to 12 carbon atoms (for example, phenol), and polyhydric alcohols having 2 to 12 carbon atoms such as ethylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, and glycerin. A polyhydric alcohol is mentioned. A saturated or unsaturated fatty acid or alcohol can be used.

Specific examples of the water-insoluble organic compound include (1) aliphatic carboxylic acid ester, (2) aromatic carboxylic acid ester, (3) phosphoric acid ester, (4) cycloalkane (ken) carboxylic acid ester, (5) Oxyacid ester, (6) glycol ester, (7) epoxy ester, (8) sulfonamide, (9) polyester, (10) glyceryl alkyl ether, (11) glyceryl alkyl ester, (12) glycol alkyl ether, ( 13) glycol alkyl ester, (14) ether or ester of trimethylolpropane, (15) ether or ester of pentaerythritol, and the like.
Among these, from the viewpoint of image clarity and gloss, the compounds of (1) to (3), (5), (8) and (10) are preferable, and (1) aliphatic di- or tricarboxylic acid ester, It is preferably at least one selected from the group consisting of (2) aromatic carboxylic acid esters and (3) phosphoric acid esters, (1) aliphatic dicarboxylic acid esters, (2) aromatic di- or tricarboxylic acid esters And (3) it is most preferably at least one selected from the group consisting of phosphate esters.

  (1) The aliphatic carboxylic acid ester is preferably an aliphatic di- or tricarboxylic acid ester from the viewpoint of image clarity. The aliphatic dicarboxylic acid ester is preferably a compound represented by the following formula (1).

（式（１）中、Ｒ¹及びＲ²はそれぞれ、水素原子、炭素数１〜１８の直鎖、分岐鎖又は環状の炭化水素基、炭素数７〜２２のアラルキル基、炭素数６〜２２のアリール基、又は炭素数２〜１０のグリコールエーテル基を示す。Ｒ¹及びＲ²は同一でも異なっていてもよい。Ｒ³は炭素数１〜１８の、不飽和基を有していてもよい、２価の脂肪族炭化水素基を示す。Ｒ¹〜Ｒ³は置換基を有していてもよい。ｎは０〜２０の平均付加モル数を示し、ＡＯはアルキレンオキシ基を示す。）

(In formula (1), R ¹ and R ² are each a hydrogen atom, a linear, branched or cyclic hydrocarbon group having 1 to 18 carbon atoms, an aralkyl group having 7 to 22 carbon atoms, and 6 to 22 carbon atoms. R ¹ and R ² may be the same or different, and R ³ may have an unsaturated group having 1 to 18 carbon atoms. A divalent aliphatic hydrocarbon group, R ^{1 to} R ³ may have a substituent, n represents an average addition mole number of 0 to 20, and AO represents an alkyleneoxy group. )

R ¹ and R ² are preferably a linear or branched alkyl group or alkenyl group having 2 to 18 carbon atoms, more preferably 4 to 12 carbon atoms, from the viewpoint of improving glossiness and image clarity of printed matter. Specific examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, hexyl group, 2-ethylhexyl group, octyl group, dodecyl group, cetyl group and the like. The same applies to the following equations.
R ³ is preferably an alkylene group or an alkenylene group, and specifically includes an ethylene group, a propylene group, a trimethylene grave, a butylene group, a hexylene group, a 2-ethylhexylene group, an octylene group, a dodecylene group, and the like. Is an alkylene group having 2 to 15 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms. The same applies to the following equations.
n is preferably 0 to 15, more preferably 0 to 12, and particularly preferably 2 to 10.
AO is an alkyleneoxy group having 2 to 4 carbon atoms such as ethyleneoxy group (EO), propyleneoxy group (PO), or butyleneoxy group (BO). When n is 2 or more, AO is the same or different. If they are different, AO may be added in blocks or randomly.
Examples of the substituent that can be bonded to R ^{1 to} R ³ include halogen atoms such as fluorine, chlorine and bromine atoms, and carbon atoms of 1 to 3 such as methyl, ethyl, propyl, isopropyl, isobutyl, t-butyl, hexyl and lauryl. 12 alkyl groups, cycloalkyl groups such as cyclohexyl groups, aryl groups such as phenyl groups, alkoxy groups having 1 to 12 carbon atoms such as methoxy, ethoxy and isopropoxy groups, aryloxy groups such as phenyloxy groups, methoxycarbonyl groups Examples include alkoxycarbonyl groups such as acetyl, acyl groups such as acetyl and benzoyl groups, acyloxy groups such as acetyloxy groups, cyano groups, nitro groups, hydroxyl groups, carboxy groups, oxo groups, epoxy groups, ether groups, and ester groups. . These substituents may be one or a combination of two or more.

(1) Specific examples of the aliphatic dicarboxylic acid ester include dimethyl adipate, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis (butyldiethylene glycol) adipate, dimethyl sebacate And aliphatic dibasic acid esters such as diethyl sebacate, dibutyl sebacate, bis (2-ethylhexyl) sebacate, diethyl succinate and bis (2-ethylhexyl) azelate. Among these, diethyl adipate, dibutyl adipate, diisobutyl adipate, bis (butyldiethylene glycol) adipate, bis (octoxypolyethylene glycol) adipate (R ¹ and R ² are both 2-ethylhexyl, AO = EO, average added mole number n = 4, 6 or 8), diesters of aliphatic dibasic acids having 6 to 10 carbon atoms such as diethyl sebacate, dibutyl sebacate and diisobutyl sebacate are particularly preferred. Examples of the aliphatic tricarboxylic acid ester include an ester of citric acid.

  (2) The aromatic carboxylic acid ester is preferably a (di or tri) carboxylic acid ester represented by the following formula (2).

(In formula (2), R ¹ and R ² are the same as described above. R ¹ and R ² may be the same or different.)

  (2) Specific examples of the aromatic carboxylic acid ester include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, bis (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, octyl benzyl Phthalate esters such as phthalate, nonylbenzyl phthalate, stearyl benzyl phthalate, octyl decyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, bis (dimethylcyclohexyl) phthalate, bis (t-butylcyclohexyl) phthalate, ethyl phthalyl ethyl glycolate, dibutyl tri Trimellitic acid esters such as melitrate, diisobutyl trimellitate, tris (2-ethylhexyl) trimellitate And the like. Among these, 3 carbon atoms such as phthalic acid diester having an aliphatic alcohol residue having 1 to 5 carbon atoms such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, octyl benzyl phthalate, nonyl benzyl phthalate, stearyl benzyl phthalate Particularly preferred are benzyl phthalate having an alkyl group of -18, and trimellitic acid diester having an aliphatic alcohol residue of 3 to 5 carbon atoms such as dibutyl trimellitate and diisobutyl trimellitate. The aromatic carboxylic acid ester is preferably an aromatic di- or tricarboxylic acid ester.

  (3) The phosphate ester is preferably a compound represented by the following formula (3).

(In formula (3), R ¹ and R ² are the same as described above. R ¹ and R ² may be the same or different.)

(3) Specific examples of phosphate esters include tributyl phosphate, tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2 -Ethylhexyl diphenyl phosphate and the like. Among these, phosphate esters having a C5-C9 alkoxyalkyl group such as tris (butoxyethyl) phosphate, phosphate esters having a C4-12 aliphatic hydrocarbon group such as tributyl phosphate, tris ( Butoxyethyl) phosphates, tricresyl phosphates, trixylenyl phosphates, cresyl diphenyl phosphates, and other phosphate esters having an aromatic hydrocarbon group of 7 to 12 carbon atoms are particularly preferred. The phosphoric acid ester is preferably a phosphoric acid di- or triester.

(4) The cycloalkane (ken) carboxylic acid ester includes a cyclic hydrocarbon group having 3 to 8 carbon atoms, which may have one unsaturated group, and is represented by the following formula (4). Cyclohexane (cene) dicarboxylic acid ester is preferred.

(In formula (4), R ¹ and R ² are the same as above. R ¹ and R ² may be the same or different.)
(4) Specific examples of cycloalkane (ken) dicarboxylic acid esters include cyclohexane esters such as 1,2-cyclohexanedicarboxylic acid dibutyl ester, 1,2-cyclohexanedicarboxylic acid diisononyl ester, and dibutyl 3,4-cyclohexene dicarboxylate. Examples include esters and cyclohexene esters such as 3,4-cyclohexenecarboxylic acid diisononyl ester.

(5) The oxyacid ester is preferably a compound represented by the following formula (5).

(In formula (5), R ¹ , R ² and R ³ are the same as described above. R ¹ and R ² may be the same or different.)
(5) Specific examples of oxyacid esters include triethyl acetylcitrate, tributyl acetylcitrate, and methyl acetylricinoleate.

(6) The glycol ester is preferably a compound represented by the following formula (6).

(In formula (6), R ¹ , R ² and R ³ are the same as described above. R ¹ and R ² may be the same or different.)
(6) Specific examples of glycol esters include diethylene glycol dibenzoate, triethylene glycol di (2-ethylhexoate), and the like.

(7) The epoxy ester is preferably a compound represented by the following formula (7).

(In Formula (7), R ¹ is the same as above. R ⁴ and R ⁵ are each independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and R ⁶ is an alkylene group having 1 to ⁶ carbon atoms. Show.)
(7) Specific examples of the epoxy ester include butyl epoxy stearate and octyl epoxy stearate.

(8) The sulfonamide is preferably a compound represented by the following formula (8).

(In formula (8), R ¹ and R ² are the same as described above. R ¹ and R ² may be the same or different.)
(8) Specific examples of the sulfonamide include o- and p-toluenesulfonamide, N-butylbenzenesulfonamide and the like.

(9) The polyester is preferably a compound represented by the following formula (9).

(In the formula (9), R ¹ , R ² and R ³ are the same as above. R ¹ and R ² and each R ³ may be the same or different. M is 1 to 18, preferably 1 to 1. Represents the number 10)
(9) Specific examples of polyester include poly (1,2-butanediol adipate), poly (1,3-butanediol adipate) and the like.

(10) Specific examples of the glyceryl alkyl ether include glyceryl monoether, glyceryl diether, and glyceryl triether. In these, the glyceryl monoether which has a C8-C30 linear or branched alkyl group is preferable. The alkyl group has 8 to 30 carbon atoms, preferably 8 to 22 carbon atoms, and more preferably 8 to 14 carbon atoms. Examples of the alkyl group include 2-ethylhexyl, (iso) octyl, (iso) decyl, (iso) dodecyl, (iso) myristyl, (iso) cetyl, (iso) stearyl, and (iso) behenyl groups. There is no restriction | limiting in particular about the position of an alkyl group, Either 1-alkyl glyceryl monoether and 2-alkyl glyceryl monoether may be sufficient.

(11) Specific examples of the glyceryl alkyl ester include glyceryl monoalkyl ester, glyceryl dialkyl ester, and glyceryl trialkyl ester.
Among these, a linear or branched aliphatic carboxylic acid having 1 to 18 carbon atoms, preferably 2 to 10 carbon atoms (for example, acetic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, palmitic acid) Linear aliphatic carboxylic acids such as branched aliphatic carboxylic acids such as pivalic acid) esters are preferred. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.
More specifically, glyceryl triacetate, glyceryl diacetate, glyceryl monoacetate and the like can be mentioned.

(12) Specific examples of glycol alkyl ether include glycol monoalkyl ether and glycol dialkyl ether.
(13) Specific examples of glycol alkyl esters include glycol monoalkyl esters and glycol dialkyl esters.
Examples of the glycols (12) and (13) include ethylene glycol and neopentyl glycol, and examples of the alkyl group include linear or branched alkyl groups having 1 to 22 carbon atoms. The total carbon number of the alkyl group is preferably 6 or more, and more preferably 8 or more.
Said water-insoluble organic compound (1)-(15) can be used individually or in mixture of 2 or more types.
As the water contained in the color ink and the clear ink, pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water can be used. In particular, the use of water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide is preferable in that the clear ink composition can be stored for a long period of time by preventing the generation of mold and bacteria.
In addition, the color ink and the clear ink can contain an organic solvent from the viewpoints of control of penetration and drying on the recording medium, prevention of nozzle clogging, and the like. As the organic solvent, compounds that are usually contained in the ink composition can be used without any particular limitation. For example, glycerin, 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, 2-butene-1,4-diol 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-hexanediol, 1,2-pentanediol, 1,5-pentanediol Polyhydric alcohols such as 4-methyl-1,2-pentanediol; glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, sorbitol, maltose, cellobiose, lacto Sugars such as sugar, sucrose, trehalose, maltotriose; sugar alcohols; hyaluronic acids; so-called solid wetting agents such as trimethylolethane, trimethylolpropane, urea, urea derivatives (dimethylurea, etc.); ethanol, methanol, butanol, C1-C4 alkyl alcohols such as propanol and isopropanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n -Propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol monobutyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol Monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n- Glycols such as propyl ether and dipropylene glycol mono-iso-propyl ether Ethers; 2-pyrrolidone, N-methyl-2-pyrrolidone; 1, -dimethyl-2-imidazolidinone; formamide, acetamide; dimethyl sulfoxide; sorbitol, sorbitan; acetin, diacetin, triacetin; 1 type (s) or 2 or more types can be used.
It is preferable that the color ink and the clear ink further contain a pH adjusting agent. As the pH adjuster, alkali hydroxides such as lithium hydroxide, potassium hydroxide and sodium hydroxide and / or alkanolamines such as ammonia, triethanolamine, tripropanolamine, diethanolamine and monoethanolamine can be used. . In particular, it is preferably adjusted to pH 6 to 10 including at least one pH adjusting agent selected from alkali metal hydroxide, ammonia, triethanolamine, and tripropanolamine. If the pH is out of this range, the material constituting the ink jet printer will be adversely affected, and the clogging recoverability will deteriorate.
As the surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant and a nonionic surfactant can be contained. A nonionic surfactant is particularly preferable from the viewpoint of obtaining an ink composition with less foaming and foaming.
Further specific examples of nonionic surfactants include acetylene glycol surfactants, acetylene alcohol surfactants, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl Ethers such as allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether; polyoxyethylene oleic acid, polyoxyethylene oleic acid ester, polyoxyethylene distearic acid ester , Sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxy Esters such as ethylene monooleate and polyoxyethylene stearate; polyether-modified siloxane surfactants such as dimethylpolysiloxane; other fluorine-containing surfactants such as fluorine alkyl esters and perfluoroalkyl carboxylates Can be mentioned. The nonionic surfactant can be used alone or in combination of two or more.
Among the above nonionic surfactants, acetylene glycol surfactants and polyether-modified siloxane surfactants are particularly preferable in that they are less foamed and have excellent antifoaming performance.
Further specific examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol. 3,5-dimethyl-1-hexyne-3ol and the like, but are also commercially available, for example, Surfynol 104, 82, 465, 485, T, manufactured by Air Products, manufactured by Nisshin Chemical Co., Ltd. Olfin STG, Olfin E1010 and the like. Specific examples of the polyether-modified siloxane surfactant include BYK-345, BYK-346, BYK-347, BYK-348, UV3530, and the like manufactured by Big Chemie Japan.

Among these organic solvents, the color ink contains trialkanolamine together with the clear ink described later. In general, trialkanolamine is used as a gloss-imparting agent, but at the same time it reduces color development on plain paper, so the amount added to color ink is limited, but clear ink is not used on plain paper, so it is more Addition can increase glossiness.
Further, the color ink and the clear ink may further contain various auxiliary agents such as preservatives, antifungal agents, dissolution aids, antioxidants, surface tension adjusting agents, and / or dielectric constant adjusting agents as necessary. You can also.
In preparing the ink in the present invention, it is preferable to remove coarse particles from the viewpoint of preventing nozzle clogging. The coarse particles are removed by, for example, filtering the ink obtained by mixing the above components using a filter such as a membrane filter or a mesh filter, and removing particles of preferably 10 μm or more, more preferably 5 μm or more. Done.

In addition, the color ink and the clear ink preferably have a viscosity at 20 ° C. of 10 mPa · s or less from the viewpoint of ejection stability. Examples of the method for adjusting the viscosity within the above range include addition of a thickener and a pH adjuster, adjustment of the solid content concentration, and adjustment of the molecular weight of the polymer component.
As described above, the color ink used in the present invention is only required to contain at least a pigment and polymer fine particles. However, when a particularly preferable form is mentioned, the pigment is preferably 0.1 to 15% by weight, More preferably, it is contained in an amount of 0.5 to 8% by weight, the fine polymer particles are preferably contained in an amount of 0.1 to 30% by weight, more preferably 0.5 to 15% by weight. It is preferable to contain the organic solvent from the viewpoint of color developability and reliability of the ink composition.
The clear ink that can be used in the recording method of the present invention does not contain a colorant. However, depending on other components such as the organic solvent and the polymer fine particles in the clear ink used, the color may be slightly white or yellow.
The clear ink contains the polymer fine particles in an amount of preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight with respect to the total weight of the clear ink composition. By making the content of the fine polymer particles within the above range, a film sufficient for preventing uneven gloss and improving weather resistance without reducing the discharge stability from the printer head, quick drying, and handling safety. Can be formed on a recording medium.

  The surface tensions of the color ink and clear ink used in the ink set of the present invention are both 20 mN / m to 35 mN / m. When the surface tension of the color ink and the clear ink is in such a range, unnecessary color mixing of the clear ink and the color ink can be prevented. Further, compared with ink having a surface tension of 35 mN / m or more, the permeation speed on the recording medium is high and the drying property is excellent.

  Among the recording media used in the present invention, glossy paper is preferably a recording medium that can leave pigment particles on the surface of the recording medium. As such a recording medium, for example, a recording medium in which an ink receiving layer is provided on a substrate can be used. The ink receiving layer may be the uppermost layer of the recording medium, or may be an intermediate layer having, for example, a glossy layer thereon. Examples of such a recording medium include a so-called absorption type (also referred to as void type) recording medium containing a porous pigment and a binder polymer in the ink receiving layer, and casein, modified PVA, gelatin in the ink receiving layer. Or a so-called swelling type recording medium containing a polymer such as modified urethane is known, and any recording medium can be used in the present invention.

  Examples of the porous pigment contained in the ink receiving layer of the absorption-type recording medium include silica-based such as precipitation method, gel type, or gas-phase method, alumina hydrate such as pseudoboehmite, and silica / alumina hybrid sol. , Smectite clay, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, kaolin, clay, talc, magnesium silicate, calcium silicate, and the like, and one or more of these can be used.

  The binder polymer contained in the ink receiving layer of the absorption recording medium is not particularly limited as long as it is a compound that has a binding ability and can increase the strength of the ink receiving layer. For example, polyvinyl alcohol , Silanol-modified polyvinyl alcohol, vinyl acetate, starch, cellulose derivatives such as carboxymethyl cellulose, casein, gelatin, conjugated diene copolymer latex such as styrene-butadiene copolymer, vinyl copolymer such as ethylene-vinyl acetate copolymer, etc. An acrylic copolymer latex such as a polymer latex and a polymer of acrylic acid and methacrylic acid can be used.

  The ink receiving layer may be a fixing agent, a fluorescent whitening agent, a water-proofing agent, a fungicide, if necessary, in the case of an ink receiving layer of an absorption type recording medium or an ink receiving layer of a swelling type recording medium. Various additives such as an agent, an antiseptic, a dispersant, a surfactant, a thickener, a pH adjuster, an antifoaming agent, and / or a water retention agent can also be contained.

Examples of the substrate on which each of the ink receiving layers is provided include paper (including sized paper); resin-coated paper obtained by coating polyethylene, polypropylene, or polyester on paper; baryta paper; polyethylene terephthalate, polyethylene, or polypropylene. And a thermoplastic resin film such as synthetic paper; a sheet-like material formed of synthetic fibers.
As described above, the recording medium used in the present embodiment is not particularly limited as long as it has the ink-receiving layer on the base material. However, a particularly preferable aspect is the base material and the uppermost layer provided thereon. A recording medium having an ink receiving layer.

  According to the present invention, there is provided an ink jet recording method for forming a print image by ejecting droplets of the clear ink and the color ink in the ink jet recording ink set described above onto a recording medium. According to such a recording method, it is possible to efficiently improve color developability on plain paper and eliminate gloss unevenness on glossy paper.

  In particular, an ink jet recording method for performing recording by discharging droplets of color ink, discharging droplets of color ink, and attaching these droplets to a recording medium, wherein the clear ink and the color ink The surface tension is both 20 mN / m to 35 mN / m, and the time difference between the droplets of the clear ink and the color ink is 100 μs to 60 seconds. Is preferable in that it can be solved efficiently. For example, in the case of a printer that prints while the inkjet head scans in the main scanning direction, only clear ink is ejected in the forward scanning, and only color ink is ejected in the backward scanning without feeding the paper in the sub scanning direction. This can be achieved. In addition to this method, any method can be used as long as the color ink is discharged after the clear ink is discharged.

  In the present invention, it is preferable that the arrangement of the clear ink is determined with priority from the position overlapping the color ink with reference to the arrangement of the color ink.

  In addition, the discharge amount per unit area of the clear ink is minimized when the discharge amount per unit area of the color ink is the maximum, and the discharge amount per unit area of the clear ink is reduced per unit area of the color ink. It is preferable that the maximum amount is obtained when the discharge amount is minimum. For example, a color to be ejected onto a recording medium is detected via software such as a driver, and the pigment ink corresponding to the color is output to a printer as a signal converted into a combination of ink ejection amounts. At this time, when the amount of pigment ink applied is low, adjustment is made so that the discharge amount of the clear ink increases. On the other hand, when the amount of pigment ink applied is large, adjustment is made so that the amount of clear ink discharged is small. The clear ink discharge amount is also adjusted by the driver. In other words, the discharge amount of the clear ink composition is determined as described above based on the amount of the pigment ink applied corresponding to the color detected by the driver. Then, the determined discharge amount of the clear ink is output to the printer as a signal converted into a combination of driving amounts.

  In the present invention, the dots formed by discharging the clear ink droplet onto the recording medium are smaller than the dots formed by discharging the color ink droplet onto the recording medium. Preferably there is. For example, a method of ejecting ink droplets of different sizes from nozzles of the same diameter using a plurality of drive pulses in an inkjet head drive device, and a nozzle diameter of a clear ink row smaller than that of a color ink row in an inkjet head This can be realized by a method of ejecting ink droplets having different sizes. The present invention is not limited to this method, and any method may be used as long as the clear ink dots are smaller than the color ink dots.

  According to the present invention, there is provided a recorded matter printed by the ink jet recording ink set described above. Such recorded matter is excellent in color developability as plain paper, and gloss unevenness is eliminated as glossy paper.

Preparation of color ink composition (preparation of polymer)
Polymer synthesis examples 1 to 3
In a reaction vessel, 20 parts of methyl ethyl ketone, 0.03 part of a polymerization chain transfer agent (2-mercaptoethanol), and 10% of 200 parts of each monomer shown in Table 1 were mixed and thoroughly replaced with nitrogen gas. A mixed solution was obtained.

  On the other hand, the remaining 90% of the monomers shown in Table 1 were charged into a dropping funnel, and 0.27 part of the polymerization chain transfer agent, 60 parts of methyl ethyl ketone and a radical polymerization initiator (2,2′-azobis (2,4-dimethyl) were added. Valeronitrile)) 1.2 parts were added and mixed, and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.

  Under a nitrogen atmosphere, the mixed solution in the reaction vessel was heated to 65 ° C. while stirring, and the mixed solution in the dropping funnel was gradually dropped over 3 hours. After 2 hours at 65 ° C. from the end of dropping, a solution obtained by dissolving 0.3 part of the radical polymerization initiator in 5 parts of methyl ethyl ketone was added, and further aged at 65 ° C. for 2 hours and 70 ° C. for 2 hours to obtain a polymer solution. It was. The weight average molecular weight of the obtained polymer was measured by the above method. The results are shown in Table 1.

The details of the compounds shown in Table 1 are as follows.
(B) Styrene macromer:
Styrene macromer, manufactured by Toa Gosei Co., Ltd., trade name: AS-6 (S), number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group (d) PP-800:
Polypropylene glycol monomethacrylate (average number of moles of propylene oxide added = 13, terminal: hydroxy group): manufactured by NOF Corporation, trade name: BLEMMER PP-800
(D) 50POEP-800B:
Octoxy polyethylene glycol polypropylene glycol monomethacrylate (average added mole number of ethylene oxide = 8, average added mole number of propylene oxide = 6, terminal: 2-ethylhexyl group): manufactured by NOF Corporation, trade name: BLEMMER 50POEP-800B

Ink production example 1
30 parts of a polymer obtained by drying the polymer solution obtained in Synthesis Example 1 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and a neutralizer (5N aqueous sodium hydroxide solution) was neutralized in 60 parts.
% And 230 parts of ion-exchanged water were added to neutralize the salt-forming group, and dimethylquinacridone pigment (CI Pigment Violet 19 [PV19], manufactured by Clariant Japan Co., Ltd.) as a magenta pigment 70 parts of product name: HosterpermRed E5B02) was added and mixed with a disper blade at 20 ° C. for 1 hour. The obtained mixture was subjected to 10-pass dispersion treatment with a microfluidizer (trade name, manufactured by Microfluidics) at a pressure of 200 MPa.
After adding 250 parts of ion-exchanged water to the obtained dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, a part of water was further removed, and a 5 μm filter (acetylcellulose membrane, outer diameter: The pigment-containing graft polymer particles having a solid content concentration of 20% are removed by filtering with a 25-mL needleless syringe (Terumo Corporation) attached with 2.5 cm, manufactured by Fuji Photo Film Co., Ltd., and removing coarse particles. An aqueous dispersion was obtained.
According to the composition shown in Table 2 below, the aqueous dispersion was mixed with solvents and ultrapure water and stirred for 2 hours. Subsequently, it was filtered using a membrane filter (trade name) (manufactured by Nippon Millipore Limited) having a pore diameter of about 8 μm to prepare a magenta ink. In Table 2, the amount of each composition added is% by weight. Furthermore, the “remaining amount” of ultrapure water means that ultrapure water is added so that the total amount of the ink composition becomes 100% by weight.

Ink production example 2
35 parts of a polymer obtained by drying the polymer solution obtained in Synthesis Example 2 under reduced pressure, and a diazo pigment (CI Pigment Yellow 74 [P.Y.74], manufactured by Sanyo Dye Co., Ltd.) as a yellow pigment, Product name: FY7413) Except for using 65 parts, the same procedure as in Production Example 1 was carried out to obtain an aqueous dispersion of pigment-containing graft polymer particles having a solid content concentration of 20%. According to the composition shown in Table 2, this water dispersion was mixed with solvents and ultrapure water to prepare a yellow ink in the same manner as in Ink Production Example 1.

Ink production example 3
40 parts of a polymer obtained by drying the polymer solution obtained in Synthesis Example 3 under reduced pressure, and a phthalocyanine pigment (CI Pigment Blue 15: 4 [P.B.15: 4], Toyo Ink as a cyan pigment) Manufactured by Seisakusho Co., Ltd., trade name: LIONOGEN BLUE BGJ) Except that 60 parts were used, the same procedure as in Production Example 1 was performed to obtain an aqueous dispersion of pigment-containing graft polymer particles having a solid content concentration of 20%. According to the composition shown in Table 2, this water dispersion was mixed with solvents and ultrapure water to prepare a cyan ink in the same manner as in Ink Production Example 1.

Ink production example 4
The aqueous dispersion of pigment-containing graft polymer particles having a solid content concentration of 20% obtained in Ink Production Example 1 and dibutyl sebacate were mixed according to the amounts shown in Table 2 below, and stirred to dibutyl sebacate as a polymer. It was contained in the particles. A magenta ink was prepared from this mixed solution according to the composition shown in Table 2 in the same manner as in Ink Production Example 1.

Ink production example 5
The aqueous dispersion of pigment-containing graft polymer particles having a solid content concentration of 20% obtained in Ink Production Example 2 and dibutyl sebacate were mixed according to the amounts shown in Table 2 below, and the mixture was stirred to polymerize dibutyl sebacate. It was contained in the particles. According to the composition shown in Table 2, a yellow ink was prepared in the same manner as in ink production example 2.

Ink production example 6
The aqueous dispersion of pigment-containing graft polymer particles having a solid content concentration of 20% obtained in Ink Production Example 3 and dibutyl sebacate were mixed according to the amounts shown in Table 2 below and stirred to dibutyl sebacate as a polymer. It was contained in the particles. A cyan ink was prepared from this mixed solution according to the composition shown in Table 2 in the same manner as in Ink Production Example 3.

Ink production examples 7 to 9
Color inks shown in Table 2 were prepared in the same manner as in Ink Production Examples 4 to 6 except that dibutyl sebacate was changed to benzyl octyl phthalate.

Ink production example 10
The polymer obtained by drying the polymer solution obtained in Synthesis Example 3 under reduced pressure was mixed with solvents and ultrapure water according to the composition shown in Table 3 below, and stirred for 2 hours. Then, it filtered using the membrane filter (brand name) (made by Nippon Millipore Limited) with a hole diameter of about 8 micrometers, and prepared the clear ink.

Ink production example 11
The polymer obtained by drying under reduced pressure on the polymer solution obtained in Synthesis Example 3 and dibutyl sebacate were mixed according to the amounts shown in Table 3 and stirred to incorporate dibutyl sebacate in the polymer particles. A clear ink was prepared from this mixed solution according to the composition shown in Table 3 in the same manner as in Ink Production Example 10.

Ink production examples 12 to 13
Clear inks shown in Table 3 were prepared in the same manner as Ink Production Example 11 except that the solvents were changed.

Ink production example 14
Clear inks shown in Table 3 were prepared in the same manner as in Ink Production Example 13 except that dibutyl sebacate was changed to benzyl octyl phthalate.

Examples 1-8 and Comparative Examples 1-4
The ink compositions prepared as described above were combined as shown in Table 4 to prepare ink sets of Examples 1 to 8 and ink sets of Comparative Examples 1 to 3. As Comparative Example 4, magenta, yellow, cyan and clear inks described in Example 2 of Japanese Patent No. 3912212 were used. Further, printing was carried out according to the following printing method 1 or printing method 2.

Printing method 1
Inkjet printer PX-A650 (manufactured by Seiko Epson) was equipped with a yellow ink composition in the yellow row, a magenta ink composition in the magenta row, a cyan ink composition in the cyan row, and a clear ink composition in the black row. Printing was performed without controlling the placement position and order of each color ink and clear ink except that the amount of each color ink and clear ink was changed according to each evaluation.

Printing method 2
As with printing method 1, in addition to changing the amount of each color ink and clear ink applied according to each evaluation, each color ink and clear ink are placed so that the places where the color ink and clear ink are applied are as much as possible. One second after printing by scanning, color ink was printed by backward scanning.

(A) Evaluation of Glossiness Using magenta ink, solid printing of 50 mm × 50 mm was performed on a PM photographic paper / gloss (manufactured by Seiko Epson; trade name) with a driving amount of ² mg / cm ² . Then, it was dried at 25 ° C. for 24 hours. The gloss of the obtained printed matter was measured with a gloss meter GM-268 (manufactured by Konica Minolta; trade name). As for the glossiness, specular reflection at 20 ° was measured. Similarly, yellow ink and cyan ink were printed, and the glossiness was measured in the same manner. The obtained glossiness was evaluated based on the following criteria.
A: The average value of 20 ° glossiness of magenta, yellow, and cyan inks is 60 or more. B: The average value of 20 ° glossiness of magenta, yellow, and cyan inks is 60 or less.

(B) Evaluation of gloss unevenness Using magenta ink, solid printing of 50 mm × 50 mm was performed on a PM photo paper / gloss (made by Seiko Epson; trade name) with an impact amount of ² mg / cm ² or 0.5 mg / cm ^2. went. Then, it was dried at 25 ° C. for 24 hours. The gloss of the printed matter was measured with a gloss meter GM-268 (manufactured by Konica Minolta; trade name). As for the glossiness, specular reflection at 20 ° was measured. At this time, the glossiness was higher at ² mg / cm ² in any of the experimental examples and comparative examples. Next, clear ink is also printed on magenta ink of 0.5 mg / cm ² , and the clear ink necessary to obtain the same glossiness as that of 2 mg / cm ² of magenta ink (not printing clear ink) is used. The amount of driving was confirmed. Similarly, yellow ink and cyan ink were printed, and the required amount of clear ink was confirmed. The average value of the obtained results was evaluated based on the following criteria.

AA: Required clear ink placement amount is 1.0 mg / cm ² or less A: Necessary clear ink placement amount is 1.0 mg / cm ² or more and 1.5 mg / cm ² or less B: Required clear ink placement amount 1.5 mg / cm ² or more C: No matter how much the clear ink is applied, the glossiness of the color ink is not obtained when the applied amount is 2.0 mg / cm ^2. there were.

(C) Evaluation of Coloring on Plain Paper Using magenta ink, a solid print of 50 mm × 50 mm was performed on a XEROX 4200 (manufactured by XEROX; trade name) with a driving amount of 1 mg / cm ² . Then, it was dried at 25 ° C. for 24 hours. The OD value of the obtained printed matter was measured with Spectrolino (manufactured by Gretag Macbeth; trade name). Similarly, yellow ink and cyan ink were printed, and the OD value was measured in the same manner. The obtained OD value was evaluated based on the following criteria.
A: Average OD value of magenta, yellow and cyan inks is 1.0 or more B: Average OD value of magenta, yellow and cyan inks is 1.0 or less The results are shown in Table 4.

  INDUSTRIAL APPLICABILITY The present invention has industrial applicability as an ink set for ink jet recording, an ink jet recording method, and a recorded matter that eliminate color development on plain paper and gloss unevenness on glossy paper.

Claims (6)

A clear ink containing polymer fine particles and a water-insoluble organic compound and not containing a colorant, a pigment as a colorant, a polymer fine particle for dispersing the pigment and a water-insoluble organic compound, and not reacting with the clear ink An ink set for inkjet recording comprising color inks,
An ink set for ink jet recording, wherein the polymer fine particles are water-insoluble polymer particles obtained by copolymerizing a monomer mixture containing 1) a salt-forming group-containing monomer, 2) a macromer and / or 3) a hydrophobic monomer.   The water-insoluble organic compound is i) an ester or ether compound having two or more ester or ether bonds in the molecule, and / or ii) one or more ester or ether bonds in the molecule, a carboxy group, The ink for inkjet recording according to claim 1, which is an ester or ether compound having at least one functional group selected from the group consisting of a sulfonic acid group, a phosphoric acid residue, a carbonyl group, an epoxy group and a hydroxyl group. set.   The ink set for inkjet recording according to claim 1 or 2, wherein the color ink is at least one ink selected from magenta ink, yellow ink, and cyan ink.   The clear ink and the color ink both contain trialkanolamine, and the content of trialkanolamine in the clear ink is greater than the content of trialkanolamine in the color ink. An ink set for ink-jet recording according to claim 1.   An inkjet recording method for forming a printed image by ejecting droplets of the clear ink and the color ink on the recording medium in the inkjet recording ink set according to claim 1.   The recorded matter printed by the ink set for inkjet recording in any one of Claims 1-4.