JP6471026B2 - Inkjet recording method - Google Patents

Description

  The present invention relates to an ink jet recording method.

The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording medium and attaching them. This method is widely spread because it is easy to make full color and is inexpensive, and has many advantages such as the ability to use plain paper as a recording medium and non-contact with the substrate.
On the other hand, printing on recording media for commercial printing using low water-absorbing coated paper such as offset-coated paper or films of non-water-absorbing resin such as polyvinyl chloride resin, polypropylene resin, and polyester resin is required. It is coming.
When printing is performed on these low water-absorbing and non-water-absorbing recording media by the ink jet recording method, the liquid component absorbs slowly or does not absorb, so it takes time to dry, and solid image beading (adjacent dots) It is known that the phenomenon of spotting unevenness in the image density).

In order to solve these problems, recording with a slow absorption of the liquid component is performed by adhering the ink containing the colorant after the pretreatment for adhering the component that aggregates the colorant contained in the ink on the recording medium in advance. An ink jet recording method using a medium has been proposed.
In Cited Document 1, for the purpose of providing an ink composition, an ink set, and an image forming method using the same, which are excellent in ultraviolet curability, and also in scratch resistance and drawing properties, a water-soluble polymerizable compound and And an ink composition comprising a pigment coated with a polymer having a crosslinked structure.
For the purpose of providing an ink set and an image forming method capable of ensuring long-term ejection reliability and capable of forming an image excellent in image gloss, scratch resistance, and the like. An ink composition containing a pigment coated with a water-insoluble polymer obtained by copolymerizing a monomer mixture containing a styrenic macromonomer, polymer particles, a water-soluble organic solvent, and water is disclosed.
Cited Document 3 provides a water-based ink or the like that can perform stable ink jet recording regardless of the printing environment, can form a substantially uniform image having abrasion resistance, and can provide a high-quality image. For this purpose, an aqueous ink satisfying a specific condition is disclosed that includes a reaction liquid containing a polyvalent metal and a pigment dispersion in which the pigment is dispersed at least by an anionic polymer dispersant.

JP 2011-178895 A JP 2011-38025 A JP 2005-298809 A

However, although the techniques described in Patent Documents 1 to 3 are used as an inkjet recording method, beading is suppressed to some extent, but the scratch resistance is insufficient, and from the viewpoint of achieving both suppression of beading and scratch resistance. There is a need for further improvement in ink composition.
The present invention suppresses beading in a recording medium (hereinafter also referred to as “low-water-absorbing recording medium”) having a water absorption of 10 g / m ² or less and 0 g / m ² or more at a contact time of 100 msec with pure water. It is an object of the present invention to provide an ink jet recording method capable of satisfying both scratch resistance and scratch resistance.
In this specification, “low water absorption” is a concept including non-water absorption, and the water absorption amount of the recording medium at a contact time of 100 msec between the recording medium and pure water is 10 g / m ² or less and 0 g / m. ^It refers to ^two or more.

  The present inventors have prepared a pretreatment liquid (hereinafter referred to as “pretreatment liquid”) containing a flocculant for aggregating components in a water-based ink for ink jet recording (hereinafter also referred to as “water-based ink”) on a low water-absorbing recording medium. In the ink jet recording method in which the water-based ink containing polymer particles containing a colorant as a component is attached to the portion of the recording medium to which the pretreatment liquid is attached. It has been found that the above-mentioned problems can be solved by adding a specific amount of a structural unit derived from a monomer having a crosslinked structure and having a specific structure to the anionic polymer constituting the polymer particles.

That is, the present invention is an ink jet recording method for recording on a low water-absorbing recording medium using an aqueous ink for ink jet recording, comprising the following steps 1 and 2, wherein the aqueous ink contains a colorant: This is an ink jet recording method containing Ax particles (hereinafter also referred to as “colorant-containing polymer Ax particles”).
Step 1: A step of attaching a pretreatment liquid containing a flocculant that aggregates the particles of the polymer Ax of the water-based ink to the recording medium. Step 2: A portion of the recording medium obtained in Step 1 where the pretreatment liquid is attached. Step of adhering the water-based ink by an ink jet recording method Polymer Ax: having a cross-linked structure, and among all the structural units of the polymer Ax, 17% by mass or more and 40% by mass of the structural unit derived from the monomer a1 represented by the formula (1) % Anionic polymer containing 3 mass% or more and 40 mass% or less of a structural unit derived from anionic monomer a2.

(In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is an ethanediyl group, R ³ is an alkanediyl group having 3 to 4 carbon atoms, R ⁴ is a hydrogen atom, and a hydrocarbon group having 1 to 9 carbon atoms. And m and n represent the average number of added moles, m is 3 or more and 40 or less, and n is 0 or more and 10 or less, and the structural unit represented by R ² O and R ³ O is: Any sequence order is possible.)

  According to the present invention, it is possible to provide an ink jet recording method capable of achieving both suppression of beading and scratch resistance.

2 is a digital microscopic image of a printed matter obtained in Example 2. FIG. 7 is a digital microscopic image of a printed matter obtained in Reference Example 5. 7 is a digital microscope image of the printed matter obtained in Reference Example 6. 7 is a digital microscopic image of a printed matter obtained in Comparative Example 6.

[Inkjet recording method]
The ink jet recording method of the present invention is an ink jet recording method for recording on a low water-absorbing recording medium using a water-based ink for ink-jet recording, comprising the following steps 1 and 2, wherein the water-based ink contains a colorant. The following polymer Ax particles are contained.
Step 1: A step of attaching a pretreatment liquid containing a flocculant that aggregates the particles of the polymer Ax of the water-based ink to the recording medium. Step 2: A portion of the recording medium obtained in Step 1 where the pretreatment liquid is attached. Step of adhering the water-based ink by an ink jet recording method Polymer Ax: having a cross-linked structure and out of all the structural units of the polymer Ax, the structural unit derived from the monomer a1 represented by the formula (1) is 17% by mass or more and 40% % Anionic polymer containing 3 mass% or more and 40 mass% or less of a structural unit derived from anionic monomer a2.

(In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is an ethanediyl group, R ³ is an alkanediyl group having 3 to 4 carbon atoms, R ⁴ is a hydrogen atom, and a hydrocarbon group having 1 to 9 carbon atoms. And m and n represent the average number of added moles, m is 3 or more and 40 or less, and n is 0 or more and 10 or less, and the structural unit represented by R ² O and R ³ O is: Any sequence order is possible.)

According to the ink jet recording method of the present invention, it is possible to achieve both suppression of beading and scratch resistance. The reason is not clear, but it is thought as follows.
In the ink jet recording method of the present invention, the colorant-containing polymer contained in the water-based ink is obtained by adhering the pretreatment liquid to the low water-absorbing recording medium and then adhering the water-based ink to the portion where the pretreatment liquid is adhered. Ax particles agglomerate in contact with the aggregating agent in the pretreatment liquid. With respect to the anionic polymer constituting the colorant-containing polymer Ax particles, by containing a specific amount of a structural unit having a crosslinked structure and a specific structure in the polymer, rapid aggregation is reduced, Thus, the liquid component in the water-based ink quickly permeates and evaporates, whereby a strong film is formed on the recording medium, and the formation of a brittle film containing the liquid component is suppressed. Therefore, even if the recording medium has low water absorption, it is considered that beading is suppressed by controlling the above-described aggregation behavior, and a strong film is formed, and thus the scratch resistance is excellent.
“Anionic” means that when a non-neutralized substance of 1% by weight with respect to pure water is dispersed or dissolved in pure water, the supernatant or solution of the dispersion has a pH of less than 7 at 20 ° C. Or when the substance is insoluble in pure water and the pH cannot be measured clearly, the zeta potential of the dispersion dispersed in pure water is negative.
In this specification, the term “colorant” refers to pigments, dyes, and the like.

<Water-based ink for inkjet recording>
The water-based ink in the inkjet recording method of the present invention contains the colorant-containing polymer Ax particles, the polymer Ax has a crosslinked structure, and the monomer a1 represented by the formula (1) in all the structural units of the polymer Ax. It is an anionic polymer containing 17% by mass or more and 40% by mass or less of a structural unit derived from and 3% by mass or more and 40% by mass or less of a structural unit derived from an anionic monomer a2.

(Coloring agent)
The colorant is contained in the water-based ink as the colorant-containing polymer Ax particles from the viewpoint of achieving both suppression of beading and scratch resistance.
The colorant contained in the colorant-containing polymer Ax particles is preferably a pigment from the viewpoint of imparting weather resistance and water resistance to the printed matter.
The pigment may be either an inorganic pigment or an organic pigment. If necessary, they can be used in combination with extender pigments.
Examples of inorganic pigments include carbon black and metal oxides, and carbon black is preferred for black ink. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.
Examples of organic pigments include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments. As the organic pigment, any of chromatic pigments such as red, yellow, blue, orange and green can be used.
Specific examples of preferred organic pigments include C.I. I. Pigment yellow, C.I. I. Pigment Red, C.I. I. Pigment orange, C.I. I. Pigment violet, C.I. I. Pigment blue, and C.I. I. One or more types of products selected from Pigment Green are listed.

In the present invention, a self-dispersing pigment can also be used as a colorant. The self-dispersing pigment means a pigment that can be dispersed in an aqueous medium without using a surfactant or a resin by bonding a hydrophilic functional group directly or through another atomic group to the surface of the pigment. . Examples of the hydrophilic functional group include one or more selected from an anionic group such as a carboxy group and a sulfo group, and a cationic group such as a quaternary ammonium group, and the dispersion stability of the colorant-containing polymer Ax particles. From this viewpoint, an anionic group is preferable. Examples of the other atomic groups include alkanediyl groups having 2 to 12 carbon atoms, phenylene groups, and naphthylene groups. In order to make the pigment a self-dispersing pigment, for example, a necessary amount of the hydrophilic functional group may be chemically bonded to the pigment surface by a conventional method.
The amount of the hydrophilic functional group is preferably 100 μmol or more and 3,000 μmol or less per 1 g of the self-dispersing pigment. When the hydrophilic functional group is a carboxy group, it is preferably 200 μmol or more and 700 μmol or less per 1 g of the self-dispersing pigment.
The above pigments can be used alone or in admixture of two or more at any ratio.

(Polymer Ax)
The polymer Ax used for the colorant-containing polymer Ax particles is used for dispersing the colorant in an aqueous medium and maintaining the dispersion stably. From the viewpoint of achieving both suppression of beading and scratch resistance, the crosslinked structure And the structural unit derived from the monomer a1 represented by the following formula (1) in the total structural unit of the polymer Ax is contained in an amount of 17% by mass to 40% by mass, and the structural unit derived from the anionic monomer a2 3 to 40% by mass is contained.
The polymer Ax is preferably a crosslinked product of the polymer An from the viewpoint of ease of production, and the polymer An contains 17% by mass or more of the structural unit derived from the monomer a1 represented by the following formula (1) in all the structural units. More preferably, the anionic polymer contains 40% by mass or less and contains 3% by mass or more and 40% by mass or less of the structural unit derived from the anionic monomer a2.
From the viewpoint of ease of production, the polymer Ax contains a vinyl monomer (vinyl compound, vinylidene compound) containing the monomer a1 in an amount of 17% by mass to 40% by mass and the anionic monomer a2 in an amount of 3% by mass to 40% by mass. More preferably, the polymer An obtained by copolymerizing a mixture of vinylene compounds) (hereinafter also referred to as “monomer mixture”) is crosslinked by a crosslinking agent.

[Monomer a1]
The polymer Ax is a monomer a1 represented by the formula (1) (hereinafter also referred to as “monomer a1”) from the viewpoint of relieving the aggregation of the colorant-containing polymer Ax particles and achieving both suppression of beading and scratch resistance. Contains derived structural units.
R ¹ is a hydrogen atom or a methyl group, and is preferably a methyl group from the viewpoint of ease of production of the polymer Ax.
R ² is an ethanediyl group from the viewpoint of achieving both suppression of beading and scratch resistance.
R ³ is an alkanediyl group having 3 to 4 carbon atoms. The number of carbon atoms of R ³ is 3 or more and 4 or less, and preferably 3 from the viewpoint of relaxing aggregation of the colorant polymer Ax particles and achieving both suppression of beading and scratch resistance.
m is 3 or more, preferably 5 or more, and 40 or less, preferably 35 or less, from the viewpoint of relaxing aggregation of the colorant-containing polymer Ax particles and achieving both suppression of beading and scratch resistance. Preferably it is 30 or less, More preferably, it is 25 or less, More preferably, it is 20 or less, More preferably, it is 15 or less, More preferably, it is 10 or less.
n is 0 or more and 10 or less, preferably 7 or less, more preferably 5 or less, from the viewpoint of relieving the aggregation of the colorant-containing polymer Ax particles and achieving both suppression of beading and scratch resistance. More preferably, it is 3 or less, and more preferably 0.
R ⁴ is one or more selected from a hydrogen atom and a hydrocarbon group having 1 to 9 carbon atoms. R ⁴ is preferably one or more selected from a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, and a phenyl group in which the hydrogen atom may be substituted with an alkyl group having 1 to 3 carbon atoms. Preferably, it is at least one selected from alkyl groups having 1 to 9 carbon atoms and phenyl groups in which hydrogen atoms may be substituted with alkyl groups having 1 to 3 carbon atoms, more preferably 1 to 9 carbon atoms. It is an alkyl group.
The number of carbon atoms of R ⁴ which is an alkyl group is 1 or more, and 9 or less, preferably 8 from the viewpoint of relieving aggregation of the colorant-containing polymer Ax particles and achieving both suppression of beading and scratch resistance. Hereinafter, it is more preferably 5 or less, further preferably 3 or less, and still more preferably 1.

Monomer a1 is preferably polyethylene glycol mono (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, ethoxy from the viewpoint of alleviating the aggregation of the colorant-containing polymer Ax particles and achieving both suppression of beading and scratch resistance. One selected from polyethylene glycol mono (meth) acrylate, propoxypolyethylene glycol mono (meth) acrylate, butoxypolyethylene glycol mono (meth) acrylate, octoxypolyethylene glycol mono (meth) acrylate, and phenoxypolyethylene glycol mono (meth) acrylate More preferably, methoxypolyethylene glycol mono (meth) acrylate, butoxypolyethylene glycol mono (meth) acrylate, octoxy One or more selected from reethylene glycol mono (meth) acrylate and phenoxypolyethylene glycol mono (meth) acrylate, more preferably one selected from methoxypolyethylene glycol mono (meth) acrylate and phenoxypolyethylene glycol mono (meth) acrylate As described above, methoxypolyethylene glycol mono (meth) acrylate is more preferable.
In the present specification, “(meth) acrylate” means one or more selected from acrylate and methacrylate.
As commercially available monomer a1, NK ester M-20G, 40G, 60G, 90G, NK ester M-230G, NK ester EH4E, NK ester PHG6G (above, Shin Nakamura Chemical Co., Ltd.) , MPG-130MA, MA-80 (manufactured by Nippon Emulsifier Co., Ltd.), light ester 041MA (manufactured by Kyoeisha Chemical Co., Ltd.) and the like.

[Anionic monomer a2]
The polymer Ax contains the dispersion stability of the colorant aqueous dispersion and the water-based ink used in the production of “an aqueous dispersion of the colorant-containing polymer Ax particles” (hereinafter also referred to as “colorant aqueous dispersion”). From the viewpoint of improving storage stability, it contains a structural unit derived from an anionic monomer a2 (hereinafter also referred to as “monomer a2”).
Examples of the monomer a2 include a carboxylic acid monomer, a sulfonic acid monomer, and a phosphoric acid monomer.
Examples of the 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 sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and 3-sulfopropyl (meth) acrylate.
Examples of the phosphoric acid monomer include vinyl phosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, and the like.
The anionic monomer is preferably a carboxylic acid monomer, more preferably acrylic acid and methacrylic acid, and still more preferably methacrylic acid, from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion and the storage stability of the water-based ink. is there.

[Aromatic monomer a3]
The polymer Ax preferably further contains a structural unit derived from the aromatic monomer a3 from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion and the storage stability of the aqueous ink.
The aromatic monomer a3 (hereinafter also referred to as “monomer a3”) is preferably at least one selected from styrene monomers, aromatic group-containing (meth) acrylates, and styrene macromonomers.
The styrene monomer is preferably styrene or 2-methylstyrene, and more preferably styrene, from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, the storage stability of the water-based ink, and the scratch resistance.
As the aromatic group-containing (meth) acrylate, benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are used from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, the storage stability of the water-based ink, and the scratch resistance. Is preferred, and benzyl (meth) acrylate is more preferred.

The styrenic macromonomer is a compound having a polymerizable functional group at one end and a number average molecular weight of 500 to 100,000, the dispersion stability of the colorant aqueous dispersion, the storage stability of the water-based ink, and the scratch resistance. From the viewpoint of improving the viscosity, it is preferably 1,000 or more and 10,000 or less. The number average molecular weight is a value measured using polystyrene as a standard substance by gel permeation chromatography using chloroform containing 1 mmol / L dodecyldimethylamine as a solvent.
Examples of commercially available styrenic macromonomers include AS-6 (S), AN-6 (S), HS-6 (S) (trade name of Toagosei Co., Ltd.), and the like.

  The aromatic monomer a3 is preferably selected from aromatic group-containing (meth) acrylates and styrenic macromonomers from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, the storage stability of the water-based ink, and the scratch resistance. More preferably, it is a combined use of an aromatic group-containing (meth) acrylate and a styrenic macromonomer, and more preferably a combined use of benzyl (meth) acrylate and a styrenic macromonomer.

The polymer Ax used in the present invention is a monomer other than the monomer a1, the anionic monomer a2, and the aromatic monomer a3 represented by the formula (1) (hereinafter referred to as “a”) within the range not impairing the effects of the present invention. It may also contain structural units derived from other monomers ”.
Other monomers include alkyl (meth) acrylates having 1 to 22 carbon atoms such as methyl (meth) acrylate and 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and 3-hydroxypropyl (meth) acrylate. And the like, and silicone-based macromonomers such as organopolysiloxane having a polymerizable functional group at one end, and the like.

[Content of each structural unit]
The content of the structural unit derived from the monomer a1 in all the structural units of the polymer Ax is 17% by mass or more, preferably 18% by mass or more, and more preferably 19% by mass from the viewpoint of achieving both suppression of beading and scratch resistance. % Or more, and 40% by mass or less, preferably 35% by mass or less, more preferably 30% by mass or less, and still more preferably 25% by mass or less.
From the viewpoint of improving the dispersion stability of the colorant aqueous dispersion and the storage stability of the water-based ink, the content of the structural unit derived from the monomer a2 in all the structural units of the polymer Ax is 3% by mass or more, preferably 5% by mass. % Or more, more preferably 8% by mass or more, and 40% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less.
The content of the structural unit derived from the monomer a3 in all the structural units of the polymer Ax is from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, the storage stability of the water-based ink, and the scratch resistance. It is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less. is there.
When using a styrenic macromonomer as the monomer a3, the content of the structural unit derived from the styrenic macromonomer in all the structural units of the polymer Ax improves the dispersion stability of the colorant aqueous dispersion and the storage stability of the aqueous ink. From the viewpoint of improving the scratch resistance and the scratch resistance, it is preferably 5% by mass or more, more preferably 8% by mass or more, and preferably 15% by mass or less, more preferably 12% by mass or less.

The polymer Ax is obtained by crosslinking a polymer An obtained by copolymerizing a monomer mixture containing the monomer a1, the anionic monomer a2, and the aromatic monomer a3 represented by the formula (1) by a known addition polymerization method with a crosslinking agent. It is preferable to obtain it.
The contents of the monomers a1, a2 and a3 (contents as unneutralized amounts; the same applies hereinafter) in the monomer mixture at the time of polymer An production are as follows.
The content of the monomer a1 is 17% by mass or more, preferably 18% by mass or more, more preferably 19% by mass or more, and 40% by mass or less from the viewpoint of achieving both suppression of beading and scratch resistance. Preferably it is 35 mass% or less, More preferably, it is 30 mass% or less, More preferably, it is 25 mass% or less.
The content of the monomer a2 is 3% by mass or more, preferably 5% by mass or more, more preferably 8% by mass or more from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion and the storage stability of the water-based ink. And it is 40 mass% or less, Preferably it is 25 mass% or less, More preferably, it is 20 mass% or less, More preferably, it is 15 mass% or less.
The content of the monomer a3 is preferably 30% by mass or more, more preferably 40% by mass or more, from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, the storage stability of the water-based ink, and the scratch resistance. The amount is preferably 50% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, and still more preferably 70% by mass or less.
When using a styrenic macromonomer as the monomer a3, the content is preferably 5% by mass or more from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, the storage stability of the aqueous ink, and the scratch resistance. More preferably, it is 8 mass% or more, and preferably 15 mass% or less, More preferably, 12 mass% or less.

[Production of Polymer An]
The polymer An is preferably obtained by copolymerizing the monomer mixture by a known addition polymerization method. As the polymerization method, a solution polymerization method is preferable.
Although there is no restriction | limiting in the organic solvent used by a solution polymerization method, From a viewpoint of improving productivity of manufacture of the coloring agent aqueous dispersion mentioned later, 1 type chosen from C4-C8 ketone, alcohol, ether, and ester The above compounds are preferable, ketones having 4 to 8 carbon atoms are more preferable, and methyl ethyl ketone is more preferable.
In the polymerization, a polymerization initiator or a polymerization chain transfer agent can be used. As the polymerization initiator, an azo compound is more preferable, and 2,2′-azobis (2,4-dimethylvaleronitrile) is more preferable.
As the polymerization chain transfer agent, mercaptans are preferable, and 2-mercaptoethanol and the like are more preferable.

Although preferable polymerization conditions vary depending on the type of polymerization initiator and the like, the polymerization temperature is preferably 50 ° C. or higher and 90 ° C. or lower, and the polymerization time is preferably 1 hour or longer and 20 hours or shorter. 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. From the obtained polymer, unreacted monomers and the like can be removed by reprecipitation, membrane separation, chromatographic methods, extraction methods and the like.
From the viewpoint of improving the productivity of the colorant aqueous dispersion, the polymer An is used as an organic solvent for obtaining an aqueous dispersion described later without removing the solvent used in the polymerization reaction. It is preferably used as a solution.
From the viewpoint of improving the productivity of the colorant aqueous dispersion, the solid content concentration of the polymer An solution is preferably 30% by mass or more, more preferably 40% by mass or more, and preferably 60% by mass or less, and 50% by mass. % Or less is more preferable.

[Polymer An]
The polymer An is a polymer before crosslinking of the polymer Ax, and is preferably a water-insoluble polymer from the viewpoint of dispersion stability in the production of the colorant aqueous dispersion described later. Here, the “water-insoluble polymer” refers to a polymer that has been dried at 105 ° C. for 2 hours and has reached a constant weight and dissolved in 100 g of water at 25 ° C., and its dissolved amount is 10 g or less. The dissolved amount is preferably 5 g or less, more preferably 1 g or less. In the case of an anionic polymer, the dissolution amount is the dissolution amount when the anionic group of the polymer is neutralized 100% with sodium hydroxide.
The content of the structural unit derived from the monomer a1 among all the structural units of the polymer An is 17% by mass or more, preferably 18% by mass or more, more preferably 19% by mass from the viewpoint of achieving both suppression of beading and scratch resistance. % Or more, and 40% by mass or less, preferably 35% by mass or less, more preferably 30% by mass or less, and still more preferably 25% by mass or less.
From the viewpoint of improving the content of the structural unit derived from the monomer a2, the dispersion stability of the colorant aqueous dispersion, and the storage stability of the water-based ink in all the structural units of the polymer An, 3% by mass or more, preferably 5% by mass Above, more preferably 8% by mass or more, and 40% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less.
The content of the structural unit derived from the monomer a3 in all the structural units of the polymer An is from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion and the storage stability of the water-based ink, and from the viewpoint of improving the scratch resistance. It is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less. is there.
When a styrene macromonomer is used as the monomer a3, the content of the structural unit derived from the styrene macromonomer in all the structural units of the polymer An improves the dispersion stability of the colorant aqueous dispersion and the storage stability of the aqueous ink. From the viewpoint of improving the scratch resistance and the scratch resistance, it is preferably 5% by mass or more, more preferably 8% by mass or more, and preferably 15% by mass or less, more preferably 12% by mass or less.

  The weight average molecular weight of the polymer An used in the present invention is preferably 10,000 or more, more preferably 15,000 or more, from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion and the storage stability of the water-based ink. More preferably, it is 20,000 or more. The weight average molecular weight of the polymer An used in the present invention is preferably from the viewpoint of reducing the ink viscosity when the organic solvent is volatilized, increasing the dot diameter when printing on a low water-absorbing recording medium, and improving the printing density. Is 150,000 or less, more preferably 100,000 or less, still more preferably 60,000 or less, and still more preferably 40,000 or less. The weight average molecular weight of the polymer An can be measured by the method described in Examples.

(Production of colorant aqueous dispersion)
From the viewpoint of improving the productivity of the water-based ink, the colorant-containing polymer Ax particles are preferably blended with the water-based ink for inkjet recording as an aqueous dispersion (colorant water dispersion) of the colorant-containing polymer Ax particles.
The colorant aqueous dispersion can be preferably obtained by a method having the following steps p1 to p3.
Step p1: A step of dispersing a mixture containing polymer An, an organic solvent, a colorant, and water (hereinafter also referred to as “colorant mixture”) to obtain dispersion p1 Step p2: obtained in step p1 Step of removing the organic solvent from dispersion p1 to obtain dispersion p2 Step p3: Mixing dispersion p2 obtained in step p2 with a crosslinking agent to crosslink polymer An to form polymer Ax, coloring For obtaining a colorant aqueous dispersion (colorant aqueous dispersion) which is an aqueous dispersion of the agent-containing polymer Ax particles

[Step p1]
Step p1 is a step of obtaining a dispersion p1 by dispersing a mixture (colorant mixture) containing polymer An, an organic solvent, a colorant, and water.
In step p1, it is preferable to obtain a colorant mixture by mixing polymer An, an organic solvent, a colorant, water, and, if necessary, a neutralizer, a surfactant and the like. From the viewpoint of obtaining a uniform colorant mixture, first, the polymer An and the organic solvent are mixed to obtain the mixture 1, then the mixture 1, the neutralizing agent, and water are mixed to obtain the mixture 2, and the mixture 2 and the color are further colored. More preferably, a colorant mixture is obtained by mixing the colorant.

(Organic solvent)
As the organic solvent, aliphatic alcohols having 1 to 3 carbon atoms, ketones having 4 to 8 carbon atoms, ethers, esters and the like are preferable, wettability to a colorant, solubility of polymer An, and polymer From the viewpoint of improving the adsorptivity of An to the colorant, a ketone having 4 to 8 carbon atoms is more preferable, methyl ethyl ketone and methyl isobutyl ketone are more preferable, and methyl ethyl ketone is still more preferable. When the polymer An is synthesized by solution polymerization, the solvent used in the polymerization may be used as it is.
The mass ratio of the polymer An to the organic solvent [polymer An / organic solvent] is preferably 0.10 or more, more preferably from the viewpoint of improving the wettability to the colorant and the adsorptivity of the polymer An to the colorant. It is 0.15 or more, more preferably 0.20 or more, and preferably 0.90 or less, more preferably 0.80 or less, and further preferably 0.70 or less.

(Neutralizer)
In the present invention, a neutralizing agent can be used from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, the storage stability of the water-based ink, and the dischargeability. When a neutralizing agent is used, neutralization is preferably performed so that the pH of the dispersion p1 is preferably 7 or more, more preferably 7.5 or more, and the pH is preferably 11 or less, more preferably 9. It is preferable to neutralize to 5 or less.
Examples of the neutralizing agent include alkali metal hydroxides, ammonia, and organic amines.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide, and sodium hydroxide is preferable.
Examples of the organic amine include trimethylamine, ethylamine, diethylamine, triethylamine, and triethanolamine.
The neutralizing agent is preferably used as an aqueous neutralizing agent solution from the viewpoint of sufficiently and uniformly promoting neutralization. From the above viewpoint, the concentration of the neutralizing agent aqueous solution is preferably 3% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, more preferably 30% by mass or less, and preferably 25% by mass or less. More preferred.
You may use a neutralizing agent and neutralizing agent aqueous solution individually or in mixture of 2 or more types.

The mass ratio of the aqueous neutralizing agent solution to the organic solvent [neutralizing aqueous solution / organic solvent] promotes the adsorptivity of the polymer An to the colorant and the neutralization of the polymer An to improve the dispersion stability of the colorant aqueous dispersion and From the viewpoint of improving the storage stability of the water-based ink, the reduction of coarse particles, and the dischargeability of the water-based ink, it is preferably 0.01 or more, more preferably 0.05 or more, and still more preferably 0.10 or more, and Preferably it is 0.50 or less, More preferably, it is 0.30 or less, More preferably, it is 0.20 or less.
The neutralization degree of the polymer An is preferably 10 mol% or more from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, the storage stability of the water-based ink, the reduction of coarse particles, and the dischargeability of the water-based ink. More preferably, mol% or more is more preferable, 30 mol% or more is more preferable, 300 mol% or less is preferable, 200 mol% or less is more preferable, and 150 mol% or less is still more preferable.
Here, the degree of neutralization is obtained by dividing the molar equivalent of the neutralizing agent by the molar amount of the anionic group of the polymer An.

(Content of each component)
The content of the colorant is the dispersion stability of the colorant aqueous dispersion, the viewpoint of improving the productivity of the colorant water dispersion, and the viewpoint of achieving both suppression of beading and scratch resistance, in the colorant mixture, Preferably it is 10 mass% or more, More preferably, it is 12 mass% or more, More preferably, it is 15 mass% or more, Preferably it is 30 mass% or less, More preferably, it is 25 mass% or less, More preferably, it is 20 mass% or less. is there.
The content of the polymer An is preferably 2.0% by mass or more in the colorant mixture, from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion, and from the viewpoint of achieving both suppression of beading and scratch resistance. Preferably it is 4.0 mass% or more, More preferably, it is 5.0 mass% or more, Preferably it is 20 mass% or less, More preferably, it is 15 mass% or less, More preferably, it is 12.0 mass% or less.
The content of the organic solvent is preferably 10% by mass or more, more preferably in the colorant mixture, from the viewpoint of improving the dispersion stability of the colorant water dispersion and improving the productivity of the colorant water dispersion. It is 12% by mass or more, more preferably 15% by mass or more, and preferably 35% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass.
The water content is preferably 40% by mass or more, more preferably 45% in the colorant mixture from the viewpoint of improving the dispersion stability of the colorant water dispersion and from the viewpoint of improving the productivity of the colorant water dispersion. It is at least mass%, more preferably at least 50 mass%, and preferably at most 75 mass%, more preferably at most 70 mass%, still more preferably at least 65 mass%.

  The mass ratio of the colorant to the polymer An [colorant / polymer An] is preferably 20/80 or more, more preferably 30/70 or more, and still more preferably 35 from the viewpoint of achieving both suppression of beading and scratch resistance. / 65 or more, and preferably 80/20 or less, more preferably 70/30 or less, and still more preferably 65/35 or less.

(Dispersion of colorant mixture)
In step p1, the colorant mixture is further dispersed to obtain dispersion p1. In the dispersion method for obtaining the dispersion p1, the average particle diameter of the polymer An particles containing the colorant (hereinafter also referred to as “colorant-containing polymer An particles”) is atomized until the desired particle diameter is obtained in one dispersion. Preferably, after the colorant mixture is preliminarily dispersed, this dispersion is further performed by applying a shearing stress, and the average particle size of the colorant-containing polymer An particles is controlled to a desired particle size.
The preferable range of the average particle diameter of the colorant-containing polymer An particles is the same as the preferable range of the average particle diameter of the colorant-containing polymer Ax particles described later.
The temperature in the preliminary dispersion in step p1 is preferably 0 ° C. or higher, and preferably 40 ° C. or lower, more preferably 30 ° C. or lower, still more preferably 20 ° C. or lower, and the dispersion time is preferably 0.5 ° C. It is not less than time, more preferably not less than 1 hour, and preferably not more than 30 hours, more preferably not more than 10 hours, and further preferably not more than 5 hours.
When preliminarily dispersing the colorant mixture, a commonly used mixing and stirring device such as an anchor blade or a disper blade can be used. Among the mixing and stirring devices, a high-speed stirring and mixing device is preferable.

The temperature in the main dispersion in step p1 is preferably 0 ° C. or higher, and preferably 40 ° C. or lower, more preferably 30 ° C. or lower, and further preferably 20 ° C. or lower.
Examples of means for imparting the shear stress of this dispersion include a kneader such as a roll mill and a kneader, a high-pressure homogenizer such as a microfluidizer (manufactured by Microfluidics), a media-type disperser such as a paint shaker and a bead mill. Examples of commercially available media type dispersers include Ultra Apex Mill (manufactured by Kotobuki Industries Co., Ltd.), Pico Mill (manufactured by Hirota Iron Works Co., Ltd.), and the like. A plurality of these devices can be combined. Among these, it is preferable to use a high-pressure homogenizer from the viewpoint of reducing the particle size of the colorant.
When this dispersion is performed using a high-pressure homogenizer, the colorant can be controlled to have a desired particle size by controlling the processing pressure and the number of passes.
The processing pressure is preferably 60 MPaG or more, more preferably 100 MPaG or more, further preferably 130 MPaG or more, more preferably 200 MPaG or less, more preferably 180 MPaG or less, and still more preferably 160 MPaG or less, from the viewpoint of productivity and economy.
The number of passes is preferably 3 or more, more preferably 10 or more, still more preferably 15 or more, and is preferably 30 or less, more preferably 25 or less.

[Process p2]
Step p2 is a step of obtaining the dispersion p2 by removing the organic solvent from the dispersion p1 obtained in the step p1. The removal of the organic solvent can be performed by a known method.
From the viewpoint of suppressing the generation of aggregates in the process of removing the organic solvent and improving the dispersion stability of the colorant aqueous dispersion, before removing the organic solvent, the dispersion p1 obtained in the step p1 is added to the dispersion p1. It is preferable to adjust the mass ratio [organic solvent / water] of the organic solvent to water by adding water.
The mass ratio of [organic solvent / water] is preferably 0.08 or more, more preferably 0.10 or more, and preferably 0.40 or less, more preferably 0.20 or less.
The non-volatile component concentration (solid content concentration) of dispersion p1 after adjusting the mass ratio [organic solvent / water] is based on the viewpoint of suppressing the generation of aggregates in the process of removing the organic solvent, and the colorant aqueous dispersion. From the viewpoint of improving productivity, it is preferably 5% by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, More preferably, it is 16 mass% or less. A part of the water contained in the dispersion p1 may be removed simultaneously with the organic solvent.

Examples of the organic solvent removing device used in the step p2 include a batch simple distillation device, a vacuum distillation device, a thin film distillation device such as a flash evaporator, a rotary distillation device, and a stirring evaporation device. From the viewpoint of efficiently removing the organic solvent, a rotary distillation apparatus and a stirring evaporation apparatus are preferable. When removing an organic solvent from a small amount of a dispersion treatment of 5 kg or less at a time, a rotary distillation apparatus is preferable. When removing the organic solvent from a large amount of the dispersion processed product exceeding 5 kg, a stirring type evaporator is preferable. Among the rotary distillation apparatuses, a rotary vacuum distillation apparatus such as a rotary evaporator is preferable. Among the stirring type evaporators, a stirring tank thin film type evaporator and the like are preferable.
The temperature of the dispersion-treated product when removing the organic solvent can be appropriately selected depending on the type of the organic solvent to be used, but it is preferably 20 ° C. or higher, more preferably 25 ° C. or higher, more preferably 30 ° C. or higher, under reduced pressure. And preferably it is 80 degrees C or less, More preferably, it is 70 degrees C or less, More preferably, it is 65 degrees C or less.
The pressure at this time is preferably reduced pressure, and as absolute pressure, preferably 0.01 MPa or more, more preferably 0.02 MPa or more, further preferably 0.05 MPa or more, and preferably 0.1 MPa or less, More preferably, it is 0.09 MPa or less.
The time for removing the organic solvent is preferably 30 minutes or longer, more preferably 1 hour or longer, more preferably 2 hours or longer, and preferably 24 hours or shorter, more preferably 12 hours or shorter, still more preferably. 10 hours or less.
The removal of the organic solvent is preferably carried out until the solid content concentration is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 35% by mass or less, more preferably 30% by mass or less. Is preferably performed.

The organic solvent is removed as described above, and the resulting concentrate is preferably subjected to a centrifugal separation process to be separated into a liquid layer portion and a solid layer portion, and the liquid layer portion is recovered. The recovered liquid layer portion is mainly a dispersion in which the colorant-containing polymer An particles are dispersed in water, and the solid layer portion is a component mainly composed of coarse particles generated due to poor dispersion or aggregation. Therefore, the dispersion p2 can be obtained from this liquid layer portion.
The obtained dispersion p2 is preferably added with a moisturizing agent such as glycerin, an antiseptic, an antifungal agent or the like from the viewpoint of preventing drying and preventing spoilage. The organic solvent in the obtained dispersion p2 is preferably substantially removed, but may remain as long as the object of the present invention is not impaired. The amount of the residual organic solvent is preferably 0.1% by mass or less, and more preferably 0.01% by mass or less.
The nonvolatile component concentration (solid content concentration) of the obtained dispersion p2 is preferably 10% by mass or more from the viewpoint of improving the dispersion stability of the colorant aqueous dispersion and facilitating the preparation of the water-based ink. Preferably it is 15 mass% or more, Preferably it is 30 mass% or less, More preferably, it is 25 mass% or less.

[Process p3]
Step p3 is a step in which the dispersion p2 obtained in step p2 and the crosslinking agent are mixed, and the polymer An is crosslinked with the crosslinking agent to form a polymer Ax to obtain a colorant aqueous dispersion. When the anionic polymer Ax has a cross-linked structure, aggregation of the colorant-containing polymer Ax particles can be alleviated and scratch resistance can be improved.

(Crosslinking agent)
As the crosslinking agent, a compound having a functional group that reacts with the anionic group of the polymer An constituting the colorant-containing polymer An particle is preferable, and a compound having the functional group in the molecule of 2 or more, preferably 2 or more and 6 or less. More preferred.
Preferred examples of the crosslinking agent include one or more compounds selected from a compound having two or more epoxy groups in the molecule, a compound having two or more oxazoline groups in the molecule, and a compound having two or more isocyanate groups in the molecule. Among these, compounds having two or more epoxy groups in the molecule are preferable, and compounds having two or three epoxy groups in the molecule are more preferable.
As a compound having two or more epoxy groups in the molecule, glycidyl ether of polyhydric alcohol is preferable, and trimethylolpropane polyglycidyl ether is more preferable.

The amount of the crosslinking agent used is preferably 1/300 or more, more preferably 1/250 or more, in terms of the mass ratio to the polymer An [crosslinking agent / polymer An] from the viewpoint of achieving both suppression of beading and scratch resistance. More preferably, it is 1/200 or more, and preferably 1/50 or less, more preferably 1/80 or less, and further preferably 1/100 or less.
The crosslinking rate of the crosslinked polymer Ax is preferably 1 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more, and preferably 50 mol% or less, more preferably 40 mol%. Hereinafter, it is more preferably 30 mol% or less. The crosslinking rate is obtained by dividing the number of moles of reactive groups of the crosslinking agent by the number of moles of anionic groups of the polymer An.

The obtained colorant aqueous dispersion is obtained by dispersing the solid content of the colorant and the polymer Ax in water as a main medium. As a form of the colorant-containing polymer Ax particles, it is sufficient that the particles are formed by at least the colorant and the polymer Ax. Examples of the form include a particle form in which the colorant is included in the polymer Ax, a particle form in which the colorant is uniformly dispersed in the polymer Ax, a particle form in which the colorant is exposed on the surface of the polymer Ax particle, and the like. Mixtures of these are also included.
The average particle diameter of the colorant-containing polymer Ax particles in the colorant aqueous dispersion is a viewpoint that improves the dispersion stability of the colorant aqueous dispersion by promoting the adsorptivity of the polymer Ax to the colorant and neutralizing the polymer. As a result, from the viewpoint of reducing coarse particles, lowering the ink viscosity during solvent volatilization, and achieving both suppression of beading and scratch resistance, preferably 40 nm or more, more preferably 60 nm or more, and even more preferably 75 nm or more. And preferably 150 nm or less, more preferably 120 nm or less, still more preferably 115 nm or less, and still more preferably 110 nm or less.
The average particle diameter of the colorant-containing polymer Ax particles is measured by the method described in the examples.
The average particle size of the colorant-containing polymer Ax particles in the water-based ink is the same as the average particle size in the colorant water dispersion, and the preferred average particle size is the average particle size in the colorant water dispersion. This is the same as the preferred embodiment.

(Amount and content of water-based ink for inkjet recording)
The blending amount of the colorant aqueous dispersion in the water-based ink is preferably from the viewpoint of increasing the drying property on the paper surface when printing on a low water-absorbing recording medium, and achieving both suppression of beading and scratch resistance. 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, and preferably from the viewpoint of reducing the viscosity of the ink at the time of volatilization of the solvent and achieving both suppression of beading and scratch resistance. Is 80% by mass or less, more preferably 75% by mass or less, and still more preferably 70% by mass or less.

  The content of the colorant in the water-based ink is preferably 1% by mass from the viewpoint of quick drying on the paper surface when printing on a low water-absorbing recording medium, and achieving both suppression of beading and scratch resistance. More preferably, it is 3% by mass or more, more preferably 5% by mass or more, and preferably 15% by mass from the viewpoint of reducing the viscosity of the ink when the solvent is volatilized and achieving both suppression of beading and scratch resistance. % Or less, more preferably 12% by mass or less, and still more preferably 10% by mass or less.

  The content of the polymer Ax in the water-based ink is preferably 1% by mass or more, more preferably 3% by mass or more, and still more preferably 5% from the viewpoint of improving the scratch resistance of a printed matter printed on a low water-absorbing recording medium. From the viewpoint of reducing the viscosity of the ink when the solvent is volatilized and achieving both suppression of beading and scratch resistance, it is preferably 12% by mass or less, more preferably 10% by mass or less, and still more preferably. It is 8 mass% or less.

  The content of the colorant-containing polymer Ax particles in the water-based ink is preferably from the viewpoint of increasing the drying property on the paper surface when printing on a low water-absorbing recording medium, and achieving both suppression of beading and scratch resistance. Is 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and from the viewpoint of reducing the viscosity of the ink at the time of solvent volatilization and achieving both suppression of beading and scratch resistance. Preferably it is 25 mass% or less, More preferably, it is 20 mass% or less, More preferably, it is 15 mass% or less.

(Organic solvent)
The aqueous ink for inkjet recording used in the present invention preferably contains an organic solvent from the viewpoint of achieving both suppression of beading and scratch resistance.

  Organic solvents used in water-based inks are ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4 butanediol, and 3-methyl. -1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, 1,2,4-butanetriol Polyhydric alcohols such as 1,2,3-butanetriol and petriol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol Monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoisobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol mono Polyhydric alcohol alkyl ethers such as butyl ether; nitrogen-containing heterocyclic compounds such as N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam; formamide, N-methylformamide, N, Amides such as N-dimethylformamide; monoethanolamine, diethanolamine, triethanolamine, triethanolamine Examples include amines such as ethylamine.

A plurality of polyhydric alcohols included in the concept of a polyhydric alcohol can be mixed and used, and a plurality of polyhydric alcohol alkyl ethers can also be mixed and used.
The organic solvent used in the water-based ink is preferably one or more selected from polyhydric alcohols and polyhydric alcohol alkyl ethers, more preferably from the viewpoint of achieving both storage stability of the water-based ink and suppression of beading and scratch resistance. Is a polyhydric alcohol, more preferably one or more selected from ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, and polypropylene glycol, and still more preferably from ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol. One or more selected, and still more preferably a combination of propylene glycol and diethylene glycol.

  The content of the organic solvent in the water-based ink is preferably 15% by mass or more, more preferably 20% by mass or more, and further preferably 25% by mass or more, from the viewpoint of achieving both suppression of beading and scratch resistance. And preferably it is 50 mass% or less, More preferably, it is 40 mass% or less, More preferably, it is 30 mass% or less.

  The total content of propylene glycol and diethylene glycol in the aqueous ink is preferably 15% by mass or more, more preferably 20% by mass or more, and further preferably 25% by mass from the viewpoint of achieving both suppression of beading and scratch resistance. The amount is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less.

(water)
The water content is preferably 20% by mass or more, more preferably 30% by mass or more, and still more preferably 40% by mass or more in the water-based ink for inkjet recording from the viewpoint of achieving both suppression of beading and scratch resistance. Yes, and preferably 70% by mass or less, more preferably 65% by mass or less, and still more preferably 60% by mass or less.

(Other ingredients)
Commonly used wetting agents, penetrants, dispersants, surfactants, viscosity modifiers, antifoaming agents, antiseptics, antifungal agents, rust inhibitors, and the like can be added to the water-based ink for inkjet recording.

[Method for producing water-based ink for inkjet recording]
The water-based ink for inkjet recording can be obtained by mixing and stirring a colorant aqueous dispersion, water, an organic solvent, and a surfactant as necessary. From the viewpoint of suppressing aggregation of the colorant-containing polymer Ax particles at the time of mixing, preferably after previously obtaining a mixture of water, an organic solvent and, if necessary, a surfactant or the like, the mixture and the colorant aqueous dispersion are used. Mix.

(Ink properties)
The viscosity at 32 ° C. of the water-based ink for inkjet recording is preferably 2.0 mPa · s or more, more preferably 3.0 mPa · s or more, and still more preferably 5. from the viewpoint of achieving both suppression of beading and scratch resistance. 0 mPa · s or more, and preferably 12 mPa · s or less, more preferably 9.0 mPa · s or less, and even more preferably 7.0 mPa · s or less.

  The pH of the water-based ink for inkjet recording is preferably 7.0 or more, more preferably 8.0 or more, still more preferably 8.5 or more, from the viewpoint of achieving both suppression of beading and scratch resistance. From the viewpoint of member resistance and skin irritation, it is preferably 11.0 or less, more preferably 10.0 or less, and still more preferably 9.5 or less.

<Inkjet recording method>
The ink jet recording method of the present invention is an ink jet recording method for recording on a low water-absorbing recording medium, comprising the following steps 1 and 2, wherein the aqueous ink contains colorant-containing polymer Ax particles.
Step 1: A step of attaching a pretreatment liquid containing a flocculant that aggregates the particles of the polymer Ax of the water-based ink to the recording medium. Step 2: A portion of the recording medium obtained in Step 1 where the pretreatment liquid is attached. Step of attaching the water-based ink by the ink jet recording method By performing step 1 before step 2, it is possible to achieve both suppression of beading and scratch resistance. In this case, the time from when the pretreatment liquid is adhered to the recording medium to when the water-based ink is adhered to the recording medium is not particularly limited. However, from the viewpoint of suppressing bleeding and beading, the pretreatment liquid of step 1 is used. It is preferable to have a drying step after adhering to the recording medium and before adhering the water-based ink of step 2 to the recording medium.
The ink jet recording method of the present invention can record an image by flying a water-based ink on an ink jet recording medium and printing using a known ink jet recording apparatus.

(Pretreatment liquid)
The pretreatment liquid preferably does not contain a colorant such as a pigment or a dye, and contains one or more aggregating agents (hereinafter also simply referred to as “aggregating agent”) capable of forming an agglomerate when contacted with the aqueous ink. .
When the flocculant comes into contact with the water-based ink on the low water-absorbing recording medium, the colorant-containing polymer Ax particles that are stably dispersed in the water-based ink come into contact with the flocculant in the pretreatment liquid and are colored. Aggregation of the agent-containing polymer Ax particles is promoted and has a function of showing a viscosity increasing effect.
The flocculant used in the present invention is preferably at least one selected from a cationic polymer and an organic acid or salt thereof from the viewpoint of suppression of beading.
The content of the flocculant is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, with respect to the total amount of the pretreatment liquid, from the viewpoint of suppression of beading. Preferably, it is 50 mass% or less, More preferably, it is 40 mass% or less, More preferably, it is 30 mass% or less.

[Cationic polymer]
The cationic polymer is preferably a polymer having a cationic group such as a primary to tertiary amino group, a quaternary ammonium group, or hydrazine, and the cationic polymer is a homopolymer of a monomer having a cationic group or other polymers. A copolymer with a monomer or a condensation polymer is preferred.
“Cationic” of a cationic polymer means that when an unneutralized polymer is dispersed or dissolved in pure water, the pH is higher than 7, and in the case of a polymer having a quaternary ammonium group or the like, When ions are dispersed or dissolved in pure water as hydroxide ions, the pH becomes higher than 7, or the polymer or the like is insoluble in pure water, and the pH cannot be measured clearly. This means that the zeta potential of the dispersed dispersion becomes positive.
The cationic polymer is preferably a water-soluble polymer. Here, the “water-soluble polymer” is a polymer in which the cationic polymer is dried at 105 ° C. for 2 hours, and when the polymer that has reached a constant weight is dissolved in 100 g of water at 25 ° C., the dissolved amount exceeds 10 g. The dissolution amount is preferably 20 g or more, more preferably 100 g or more.

Among the above cationic polymers, a cationic polymer having an amino group or a quaternary ammonium base is preferable from the viewpoint of achieving both suppression of beading and scratch resistance and improving the storage stability of the pretreatment liquid. .
The cationic polymer, preferably polyethylene imine, polyallylamine or an acid neutralization thereof, polydiallyl dimethyl ammonium chloride, diallyl dimethyl ammonium chloride -SO ₂ copolymer, dimethylaminoethyl methacrylate polymer or acid neutralized product thereof , Polymethacryloyloxyethyltrimethylammonium chloride, and an amine-epichlorohydrin copolymer, more preferably an amine-epichlorohydrin copolymer. These can be used alone or in combination of two or more.
The weight average molecular weight of the cationic polymer is preferably 1,000 or more, more preferably 3,000 or more, and still more preferably 4,000, from the viewpoint of suppressing beading due to good aggregation with the colorant-containing polymer Ax particles. More preferably, it is 300,000 or less, more preferably 100,000 or less, and still more preferably 40,000 or less.

  The content of the cationic polymer is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably from the total amount of the pretreatment liquid from the viewpoint of achieving both suppression of beading and scratch resistance. It is 15% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less.

[Organic acids and their salts]
The organic acid or a salt thereof can generate an aggregate by changing the pH of the water-based ink. At this time, the pH (25 ° C.) of the pretreatment liquid is preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and preferably 6 or less, from the viewpoint of the aggregation rate of the water-based ink. Preferably it is 5 or less. When the pretreatment liquid contains an organic acid or a salt thereof, the pH (25 ° C.) of the water-based ink is preferably 7.5 or more, more preferably 8 or more.
In the present invention, from the viewpoint of achieving both suppression of beading and scratch resistance, the pH (25 ° C.) of the water-based ink is 7.5 or more, and the pH (25 ° C.) of the pretreatment liquid is 1 or more and 5 or less. It is preferable that

Examples of the organic acid include a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfo group, a sulfinic acid group, a compound having a carboxyl group, or a salt thereof (for example, a polyvalent metal salt). Among these, the organic acid is preferably a compound having a phosphate group or a carboxyl group, more preferably a compound having a carboxyl group, from the viewpoint of achieving both suppression of beading and scratch resistance. The compound having a carboxyl group includes polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid. One or more selected from pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, and salts thereof are preferable.
The content of the organic acid is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass with respect to the total amount of the pretreatment liquid from the viewpoint of achieving both suppression of beading and scratch resistance. %, And preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less.

The pretreatment liquid may contain a wetting agent, a penetrating agent, a dispersing agent, a viscosity modifier, an antifoaming agent, an antifungal agent, an antirust agent and the like that are usually used for water-based inks for inkjet recording.
The pretreatment liquid can be obtained, for example, by adding a cationic polymer and an organic acid to water stirred by a stirring blade, and further adding and mixing the above additives.
The pretreatment liquid of the present invention preferably further contains an aqueous solvent such as water in addition to the cationic polymer and the organic acid or salt thereof.

In step 1, as a method of attaching the pretreatment liquid to the recording medium, spray coating, brush coating, roller coating, an ink jet method, and the like can be given, preferably a roller coating or an ink jet method, and an ink jet method is more preferable. In the case of applying the ink jet method, it is preferable to use a piezo ink jet printer.
When adopting the inkjet method, the surface tension (25 ° C.) of the pretreatment liquid is preferably 20 mN / m or more, more preferably 25 mN / m or more, from the viewpoint of achieving both beading suppression and scratch resistance. And preferably it is 45 mN / m or less, More preferably, it is 40 mN / m or less, More preferably, it is 35 mN / m or less. The viscosity (20 ° C.) of the pretreatment liquid is preferably 1.0 mPa · s or more, more preferably 1.2 mPa · s or more, and preferably 12 mPa · s or less, more preferably 10 mPa · s or less. .

(recoding media)
The recording medium used in the present invention has a water absorption amount of 10 g / m ² or less and 0 g / m ² or more at a contact time of 100 msec with pure water. The water absorption is measured by the method described in the examples.

As the recording medium, coated paper and film having low water absorption are preferably used.
As coated paper, general-purpose glossy paper “OK Top Coat Plus” (manufactured by Oji Paper Co., Ltd., basis weight 104.7 g / m ² , water absorption at a contact time of 100 milliseconds (the following water absorption is the same) 4.9 g / m ^2), multicolored foam gloss paper (manufactured by Oji paper Co., Ltd., basis weight 104.7 g / ^{m 2,} the water absorption amount ^{5.2g / m 2), UPM Finesse} gloss (UPM Co., basis weight 115 g / ^{m 2,} water 3.1 g / m ² ), UPM Finesse Matt (manufactured by UPM, basis weight 115 g / m ² , water absorption 4.4 g / m ² ), TerraPress Silk (manufactured by Stora Enso, basis weight 80 g / m ² , water absorption Amount 4.1 g / m ² ) and the like.

Examples of the film include a polyester film, a vinyl chloride film, a polypropylene film, a polyethylene film, and a nylon film. These films may be subjected to surface treatment such as corona treatment as necessary.
Examples of the film include Lumirror T60 (manufactured by Toray Industries, Inc., polyethylene terephthalate, water absorption 2.3 g / m ² ), PVC80BP (manufactured by Lintec Corporation, vinyl chloride, water absorption 1.4 g / m ² ), and the like.

(1) Measurement of weight average molecular weight Gel chromatography method [Tosoh Corporation] was prepared by using a solution obtained by dissolving phosphoric acid and lithium bromide in N, N-dimethylformamide so as to have concentrations of 60 mmol / L and 50 mmol / L, respectively. It measured using monodispersed polystyrene as a standard substance with the GPC apparatus (HLC-8120GPC) by a corporation | Co., Ltd., the column (TSK-GEL, (alpha) -Mx2 piece) by Tosoh Corporation, and a flow rate: 1 mL / min].

(2) Measurement of average particle diameter Cumulant analysis was performed using a laser particle analysis system “ELS-8000” (manufactured by Otsuka Electronics Co., Ltd.) to measure the average particle diameter of the colorant-containing polymer Ax particles. The measurement conditions were a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and the number of integrations of 100. The refractive index of water (1.333) was input as the refractive index of the dispersion solvent. The measurement concentration was 5 × 10 ⁻³ mass% (in terms of solid content concentration). Uniform Microparticles (average particle size: 204 nm) manufactured by Celadin was used as a standard substance.

(3) Measurement of solid content concentration Weigh 10.0 g of sodium sulfate constant in a desiccator into a 30 mL polypropylene container (φ = 40 mm, height = 30 mm), and add about 1.0 g of sample to it. After mixing, the sample was accurately weighed and maintained at 105 ° C. for 2 hours to remove volatile components, and further left in a desiccator for 15 minutes to measure the mass. The mass of the sample after removal of the volatile matter was taken as the solid content and divided by the mass of the added sample to obtain the solid content concentration.

(4) Measurement of water absorption when the contact time of the recording medium with pure water is 100 milliseconds Using an automatic scanning absorption meter (KM500win, manufactured by Kumagai Riki Kogyo Co., Ltd.) under the conditions of 23 ° C. and 50% relative humidity. Then, the amount of transition of pure water at a contact time of 100 ms was measured to obtain a water absorption amount of 100 ms. The measurement conditions are shown below.
"SpiralMethod"
Contact Time: 0.010〜1.0 (sec)
Pitch (mm): 7
Length Per Sampling (degree): 86.29
Start Radius (mm): 20
End Radius (mm): 60
Min Contact Time (ms): 10
Max Contact Time (ms): 1000
Sampling Pattern (1-50): 50
Number of Sampling Points (> 0): 19
"SquareHead"
Slit Span (mm): 1
Slit Width (mm): 5
General-purpose glossy paper “OK Top Coat Plus” (Oji Paper Co., Ltd.) was 4.9 g / m ² , and plain paper “4200” (Fuji Xerox Co., Ltd.) was 14.0 g / m ² .

The raw materials used in the following synthesis examples are as follows.
MAA: Methacrylic acid (Wako Pure Chemical Industries, Ltd.)
BzMA: benzyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)
AS-6S: Styrene macromonomer (“AS-6 (S)” manufactured by Toagosei Co., Ltd .; effective concentration 50 mass%, number average molecular weight 6000)

MPEGMA2: Methoxypolyethylene glycol monomethacrylate (m = 2) (“NK Ester M-20G” manufactured by Shin-Nakamura Chemical Co., Ltd.)
MPEGMA4: Methoxypolyethylene glycol monomethacrylate (m = 4) (“NK Ester M-40G” manufactured by Shin-Nakamura Chemical Co., Ltd.)
MPEGMA6: Methoxypolyethylene glycol monomethacrylate (m = 6) (“NK Ester M-60G” manufactured by Shin-Nakamura Chemical Co., Ltd.)
MPEGMA9: Methoxypolyethylene glycol monomethacrylate (m = 9) (“NK Ester M-90G” manufactured by Shin-Nakamura Chemical Co., Ltd.)
MPEGMA13: Methoxypolyethylene glycol monomethacrylate (m = 13) (“MPG-130MA” manufactured by Nippon Emulsifier Co., Ltd.)
MPEGMA 23: Methoxypolyethylene glycol monomethacrylate (m = 23) (“NK Ester M-230G” manufactured by Shin-Nakamura Chemical Co., Ltd.)
MPEGMA30: Methoxypolyethylene glycol monomethacrylate (m = 30) (“Kyoeisha Chemical Co., Ltd.“ Light Ester 041MA ”)
MPEGMA45: Methoxypolyethylene glycol monomethacrylate (m = 45) (“NK Ester M-450G” manufactured by Shin-Nakamura Chemical Co., Ltd.)
OcPEGMA8: Octoxy polyethylene glycol monomethacrylate (m = 8) (“NK Ester EH4E” manufactured by Shin-Nakamura Chemical Co., Ltd.)
HPEGMA8: Polyethylene glycol monomethacrylate (m = 8) (“MA-80” manufactured by Nippon Emulsifier Co., Ltd.)
PhPEGMA6: Phenoxypolyethylene glycol monomethacrylate (m = 6) (“NK Ester PHG6G” manufactured by Shin-Nakamura Chemical Co., Ltd.)
MPAGMA12: Methoxypolyoxythiethylenepolyoxypropylene glycol monomethacrylate (m = 6, n = 6) (“Blemmer 43PMEP650B” manufactured by NOF Corporation)
LPEGMA4: Lauroxy polyethylene glycol monomethacrylate (m = 4) (“Blemmer PLE-200” manufactured by NOF Corporation)

MEK: Methyl ethyl ketone (Wako Pure Chemical Industries, Ltd.)
V-65: 2,2′-azobis (2,4-dimethylvaleronitrile) (“V-65” manufactured by Wako Pure Chemical Industries, Ltd.)
2-ME: 2-mercaptoethanol (Wako Pure Chemical Industries, Ltd.)

Synthesis Example 1 (Production of polymer An1)
Into the reaction vessel, 11.9 g of MPEGMA9, 42.0 g of BzMA, 14.0 g of AS-6S, 0.4 g of 2-ME and 15.8 g of MEK were added as “initially charged monomer solution”, and the inside of the reaction vessel was stirred. Nitrogen gas replacement was performed, and the temperature was raised to 77 ° C. While maintaining the inside of the reaction vessel at 77 ° C. with stirring, as “Drip monomer solution 1”, MPEGMA9 95.2 g, MAA 72.8 g, BzMA 336.0 g, AS-6S 126.0 g, V-65 5.6 g, A liquid mixture of 2-ME 2.4 g and MEK 173.3 g was dropped into the reaction vessel over 3 hours under a nitrogen atmosphere. Next, as “Drip monomer solution 2”, a mixed solution of MPEGMA9 11.9 g, MAA 18.2 g, BzMA 42.0 g, V-65 1.4 g 2-ME 0.7 g and MEK 126.0 g was added under a nitrogen atmosphere. Was added dropwise to the reaction vessel over 2 hours, and the mixture was further stirred at 77 ° C. for 0.5 hour. Next, as a “ripening step”, a mixed solution of 1.1 g of V-65 and 47.3 g of MEK was added to the reaction vessel, and stirred at 77 ° C. for 0.5 hour. The aging step was repeated a total of 6 times. Next, the inside of the reaction vessel was stirred at 80 ° C. for 1 hour, and MEK was added to the reaction vessel so that the solid content concentration was 45.0% by mass to obtain a solution of polymer An1. Table 5 shows the composition and weight average molecular weight of the obtained polymer An1.

Synthesis Examples 2 to 19 (production of polymers An2 to 19)
Except that the compositions of “initial charged monomer solution”, “dropped monomer solution 1”, and “dropped monomer solution 2” were changed according to the descriptions in Tables 1 to 4, respectively, A solution was obtained. Table 5 shows the compositions and weight average molecular weights of the polymers An2 to 19 obtained.

Production Example 1-1 (Production of Colorant Water Dispersion 1)
(Process p1)
222.2 g of the polymer An1 solution (solid content concentration 45.0%) obtained in Synthesis Example 1 was mixed with 39.79 g of methyl ethyl ketone (MEK) to obtain a MEK solution of polymer An.
A MEK solution of the polymer An obtained in a disper with a volume of 2 L was added, and while stirring at 1400 rpm, 471.60 g of ion-exchanged water and 23.28 g of 5N sodium hydroxide aqueous solution were added, and sodium hydroxide was added. The mixture was adjusted to have a neutralization degree of 65% and stirred at 1400 rpm for 15 minutes while cooling with a 0 ° C. water bath.
Next, 150 g of a cyan pigment “TGR-SD” (manufactured by Toyo Ink Co., Ltd.) was added, and the mixture was stirred at 4500 rpm for 3 hours. The obtained pigment mixture was subjected to 15-pass dispersion treatment at a pressure of 150 MPaG using a microfluidizer “M-110EH-30XP” (manufactured by Microfluidics) to obtain dispersion p1. In the dispersion treatment, water was added to adjust the solid content concentration of the dispersion p1 to 25% by mass.

(Process p2)
600.0 g of dispersion p1 obtained in step p1 was put in a 2 L eggplant flask, 400.0 g of ion-exchanged water was added (solid content concentration 15.0% by mass), and a vacuum distillation apparatus “Rotary evaporator N-1000S” (Tokyo) Rika Kikai Co., Ltd.) was used for 3 hours at an absolute pressure of 0.09 MPa in a warm bath adjusted to 32 ° C. at a rotation speed of 50 rpm to remove the organic solvent. Furthermore, the warm bath was adjusted to 62 ° C., the absolute pressure was reduced to 0.07 MPa, and the solid content concentration was concentrated to 25% by mass.
The obtained concentrate was put into a 500 mL angle rotor, and centrifuged at 7000 rpm for 20 minutes using a high-speed cooling centrifuge “himac CR22G” (manufactured by Hitachi Koki Co., Ltd., set temperature: 20 ° C.). The mixture was filtered through a 5 μm membrane filter “Minisart” (Sartorius).
Ion exchange water was added to 300 g of the filtrate to obtain a dispersion p2 adjusted to a solid content concentration of 22.0% by mass.

(Process p3)
To 100 g of the dispersion p2 adjusted to a solid content concentration of 22.0% by mass obtained in the step p2, 10.74 g of ion-exchanged water and a crosslinking agent Denacol EX-321 (manufactured by Nagase ChemteX Corporation, epoxy equivalent 140) 19 g of the mixed solution was added and stirred at 70 ° C. for 5 hours. After cooling to 25 ° C., the mixture was filtered through the 5 μm filter to obtain a colorant aqueous dispersion 1 having a solid content concentration of 20.0% by mass and a crosslinking rate of 10 mol% shown in Table 6.

Production Examples 1-2 to 1-15 (Production of Colorant Water Dispersions 2 to 15)
Colorant water dispersions 2 to 15 shown in Table 6 were obtained in the same manner as in Production Example 1-1 except that the solution of polymer An1 used at the time of pigment dispersion was changed to the solutions of polymers An2 to 15 shown in Table 6.

Production Example 1-16 (Production of Colorant Aqueous Dispersion 16 with a Crosslink Rate of 5 mol%)
A colorant aqueous dispersion 16 shown in Table 6 was obtained in the same manner as in Production Example 1-1 except that 0.09 g of the crosslinking agent in Production Example 1-1 and 10.37 g of ion-exchanged water were changed.

Production Example 1-17 (Production of Colorant Water Dispersion 17 with a Crosslink Rate of 15 mol%)
A colorant water dispersion 17 shown in Table 6 was obtained in the same manner as in Production Example 1-1 except that the crosslinking agent in Production Example 1-1 was changed to 0.28 g and the ion exchange water was changed to 10.37 g.

Production Example 1-18 (Production of Colorant Aqueous Dispersion 18 with a Crosslinking Rate of 20 mol%)
A colorant water dispersion 18 shown in Table 6 was obtained in the same manner as in Production Example 1-1 except that the crosslinking agent in Production Example 1-1 was changed to 0.37 g and the ion exchange water was changed to 11.48 g.

Production Example 1-19 (Production of Colorant Aqueous Dispersion 19 with a Crosslink Rate of 25 mol%)
A colorant water dispersion 19 shown in Table 6 was obtained in the same manner as in Production Example 1-1 except that the crosslinking agent in Production Example 1-1 was changed to 0.47 g and ion-exchanged water was changed to 11.86 g.

Production Examples 1-20 to 1-23 (Production of Comparative Colorant Water Dispersions 20-23)
Except having changed the solution of polymer An1 used at the time of pigment dispersion into the solution of polymer An16-19, the colorant water dispersions 20-23 shown in Table 6 were obtained similarly to manufacture example 1-1.

Production Example 1-24 (Production of Colorant Aqueous Dispersion 24 without Crosslinking Structure)
A colorant water dispersion 24 was obtained in the same manner as in Production Example 1-1 and Table 6 except that the crosslinking agent in Production Example 1-1 was changed to 0 g and the ion exchange water was changed to 10.00 g.

Production Example 2-1 (Production of Ink 1)
66.67 g of the colorant aqueous dispersion 1 obtained in Production Example 1-1, 4.13 g of ion-exchanged water, 10.00 g of propylene glycol (Wako Pure Chemical Industries, Ltd.), diethylene glycol (Wako Pure Chemical Industries, Ltd.) ) 15.00 g, Surfynol 104PG50 (manufactured by Nissin Chemical Industry Co., Ltd.) 1.00 g, and Emulgen 120 (manufactured by Kao Corporation) 2.00 g were mixed, and the resulting mixture was filtered through the 5 μm filter to obtain ink. 1 was obtained.

Production Examples 2-2 to 2-19 (Production of Inks 2 to 19)
Inks 2 to 19 were obtained in the same manner as in Production Example 2-1, except that the colorant aqueous dispersion 1 used in Production Example 2-1 was changed to the colorant aqueous dispersion described in Table 7.

Comparative production examples 1 to 5 (production of inks C1 to C5)
Inks C1 to C5 were obtained in the same manner as in Production Example 2-1, except that the colorant aqueous dispersion 1 used in Production Example 2-1 was changed to the colorant aqueous dispersion described in Table 7.

Preparation Example 1 (Preparation of Pretreatment Solution 1)
(1) Synthesis of amine-epichlorohydrin copolymer 95.1 g of water and 58% trimethylamine hydrochloride aqueous solution 131. In a 500 ml four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube. 8 g (0.8 mol) was charged, and 74.0 g (0.8 mol) of epichlorohydrin was added dropwise over 3 hours while cooling so as not to exceed 40 ° C. while introducing nitrogen gas. After completion of the dropwise addition, the temperature was raised to 80 ° C. and the reaction was performed for 1 hour. Thereafter, the mixture was cooled to 30 ° C., 36.1 g (0.4 mol) of 50% dimethylamine aqueous solution and 14.8 g (0.2 mol) of calcium hydroxide were added, the temperature was raised to 80 ° C., and the reaction was performed over 1 hour. I let you. Thereafter, the reaction solution was adjusted with hydrochloric acid and water so as to have a pH of 4.0 and a solid content concentration of 50% to obtain an amine-epichlorohydrin copolymer.

(2) Preparation of Pretreatment Liquid 1 After blending with the following composition, stirring for 1 hour and mixing uniformly, a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm (Durapore SVLPO 4700 manufactured by Yamato Scientific Co., Ltd.) The pretreatment liquid 1 was prepared by filtration under pressure to remove coarse particles and dust. The physical properties of Pretreatment Liquid 2 were a surface tension of 20.6 mN / m and a pH of 6.44.
[Composition of pretreatment liquid 1]
Amine-epichlorohydrin copolymer obtained in Preparation Example 1 (1) 20.0%
3-methyl-1,3-butanediol 10.0%
Glycerin 20%
2-ethyl-1,3-hexanediol 1.0%
2,4,7,9-tetramethyldecane-4,7-diol 0.1%
Fluorocarbon surfactant _{(C 4 F 9 -CH 2 CH} (OH) CH 2 O- (CH 2 CH 2 O) 25 -C 12 H 25) 0.2%
Proxel GXL 0.05%
1,2,3-benzotriazole 0.05%
Ion exchange water 48.6%

Preparation Example 2 (Preparation of Pretreatment Solution 2)
After blending with the following composition, stirring for 1 hour and mixing uniformly, pressure filtration was performed with a polyvinylidene fluoride membrane filter having an average pore size of 5.0 μm (“Durapore SVLPO 4700” manufactured by Yamato Scientific Co., Ltd.) Coarse particles and dust were removed to prepare a pretreatment liquid 2. The physical properties of the pretreatment liquid 2 were a surface tension of 37.3 mN / m and a pH of 1.6.
[Composition of pretreatment liquid 2]
Malonic acid (divalent carboxylic acid, manufactured by Wako Pure Chemical Industries, Ltd.) 15.0%
Diethylene glycol monomethyl ether (Wako Pure Chemical Industries, Ltd.) 20.0%
Surfactant (N-oleoyl-N-methyltaurine sodium) 1.0%
Ion exchange water 64.0%

Example 1
(Process 1)
The pretreatment liquid 1 obtained in Preparation Example 1 was applied to printing paper (“OK Top Coat Plus” manufactured by Oji Paper Co., Ltd.) using a table coater (“TC-1” manufactured by Mitsui Denki Seiki Co., Ltd.). The precoated paper 1 was obtained by coating at a temperature of 8 g / m ² and drying at 23 ° C. for 24 hours.
(Process 2)
A commercially available inkjet printer “GX-5500” (Ricoh Co., Ltd., Piezo Method) was filled with the water-based ink 1 obtained in Production Example 2-1, and the pre-coated paper 1 was placed at 23 ° C. and a relative humidity of 50%. A4 solid image (single color) was printed, dried for 3 minutes on an analog hot plate (NINOS) NA-2 (manufactured by ASONE Co., Ltd.) heated to 80 ° C. immediately after printing, and then 23 ° C. relative Printed matter was obtained by storing overnight at a humidity of 50%.

Examples 2 to 4, 7 to 10, and 13 to 19, Comparative Examples 1 to 5 , Reference Examples 5, 6, 11, and 12
Example 1 is the same as Example 1 except that the water-based ink 1 obtained in Production Example 2-1 was changed to those obtained in Production Examples 2-2 to 2-19 and Comparative Production Examples 1 to 5. A printed matter was obtained.

Example 20
(Process 1)
Using the wire bar coater ("ROD No. 2" manufactured by Tester Sangyo Co., Ltd.) on the printing paper ("OK Topcoat Plus" manufactured by Oji Paper Co., Ltd.) It was applied so that the amount was 4.0 g / m ^2. Immediately after the application, “HOT PLATE HI-1000” manufactured by ASONE was used and dried at 50 ° C. for 2 seconds to obtain precoated paper 2.
(Process 2)
Except for changing the aqueous ink 1 obtained in Production Example 2-1 to the ink 2 obtained in Production Example 2-2 on the precoated paper 2 obtained in Step 1, the same as in Step 2 of Example 1. A printed material was obtained.

Comparative Example 6
In Example 2, a printed matter was obtained in the same manner as in Example 2 except that the precoated paper 1 in Step 2 was changed to an OK topcoat that was not pretreated without going through Step 1.

[Evaluation of scratch resistance]
Using the clock meter QC-621A (manufactured by Imoto Seisakusho Co., Ltd.), the printed matter obtained is rubbed five times (five reciprocations) using coated paper (“OK Top Coat” manufactured by Oji Paper Co., Ltd.) as a friction material. Thus, a scratch test of the printed matter was performed. The printing density of the ink transferred to the OK top coat used as the friction material after the test was measured with an optical spectrophotometer “SpectroEye” of Sakata Inx Engineering Co., Ltd. The results are shown in Table 7. The smaller the transfer density, the less ink transfer and the better the scratch resistance.

[Evaluation of beading]
About the obtained printed matter, using a digital microscope (manufactured by Trek Japan Co., Ltd., handy type image evaluation system “PIAS-II (Low resolution module)”), the state of beading is visually observed based on the following evaluation criteria. evaluated. The results are shown in Table 7.
(Evaluation criteria)
Rank A: The printed matter obtained in Example 2 shown in FIG.
Rank ◯: The printed matter obtained in Reference Example 5 shown in FIG.
Rank Δ: The printed matter obtained in Reference Example 6 shown in FIG.
Rank x: The printed matter obtained in Comparative Example 6 shown in FIG.

From Table 7, Examples 1-4, 7-10, and 13-20 are more resistant to scratching while suppressing beading when printed on a low water-absorbing recording medium as compared with Comparative Examples 1-6. It turns out that it is excellent.

Claims (8)

An inkjet recording method for recording on a recording medium using a water-based ink for inkjet recording and having a water absorption of 10 g / m ² or less and 0 g / m ² or more at a contact time of 100 msec with pure water, comprising the following steps 1 and 2 An ink jet recording method in which the water-based ink contains particles of the following polymer Ax containing a colorant.
Step 1: A step of attaching a pretreatment liquid containing a flocculant that aggregates the particles of the polymer Ax of the water-based ink to the recording medium. Step 2: A portion of the recording medium obtained in Step 1 where the pretreatment liquid is attached. Step of adhering the water-based ink by an ink jet recording method Polymer Ax: having a cross-linked structure, and among all the structural units of the polymer Ax, 17% by mass to 30 % by mass of the structural unit derived from the monomer a1 represented by the formula (1) % containing less contains a constitutional unit derived from a anion monomers a2 3 mass% to 40 mass%, and a constitutional unit derived from an aromatic monomer a3 anionic polymer containing 80 wt% or less than 30 wt% Yes, the mass ratio [colorant / polymer An] of the colorant to the polymer An before crosslinking of the polymer Ax is 20/80 or more and 70/30 or less.

(Wherein, ^{R 1} represents a hydrogen atom or a methyl group, ^{R 2} is ethanediyl group, ^{R 3} is alkanediyl group having 3 carbon atoms, ^{R 4} is a hydrogen atom, carbon number 1 to 5 alkyl groups, and a hydrogen atom It is at least one selected from phenyl groups optionally substituted with an alkyl group having 1 to 3 carbon atoms , m and n represent the average number of added moles, m is 3 to 25 and n is 0 to 10 (The structural units represented by R ² O and R ³ O may have any arrangement order.) The inkjet recording method according to claim 1 , wherein the aromatic monomer a3 is at least one selected from a styrene monomer, an aromatic group-containing (meth) acrylate, and a styrene macromonomer. The inkjet recording method according to claim 1 or 2 , wherein m is 5 or more and 25 or less. R ⁴ is an alkyl group having 1 to 5 carbon atoms, an ink jet recording method according to any one of claims 1-3. The inkjet recording method according to any one of claims 1 to 4, wherein the aqueous ink for inkjet recording contains an organic solvent, and the content of the organic solvent in the aqueous ink is 15% by mass or more and 50% by mass or less.   The inkjet recording method according to any one of claims 1 to 5, wherein the flocculant is at least one selected from a cationic polymer, an organic acid or a salt thereof. The weight average molecular weight of Po Rimmer An is 10,000 or more to 150,000 or less, the ink jet recording method according to any one of claims 1 to 6. Polymer An contains 17% by mass or more and 30 % by mass or less of the structural unit derived from monomer a1 represented by formula (1) among all the structural units of polymer An, and 3% of the structural unit derived from anionic monomer a2. The inkjet recording method according to any one of claims 1 to 7 , which is an anionic polymer containing from 30% to 40% by mass and containing from 30% by mass to 80% by mass of a structural unit derived from the aromatic monomer a3 .