JP7779177B2 - Liquid composition, ink and liquid composition set, and image forming method - Google Patents

Description

The present invention relates to a liquid composition, a set of ink and liquid composition, and an image forming method.

Inkjet printers have advantages such as low noise, low running costs, and easy color printing, making them widely used in ordinary households as digital signal output devices. In recent years, inkjet imaging technology has been developed for packaging materials such as food, beverages, and daily necessities. As a result, inkjet printers are no longer only used for home use, but are now also being used for packaging materials. Examples of substrates for packaging applications include cardboard.

Printing methods for cardboard can be broadly divided into two methods: the preprint method, in which an image is recorded with printing ink on the base cardboard paper (surface liner paper) and then the corrugator is used to attach the core and back liner paper to produce cardboard; and the postprint method, in which an image is recorded with printing ink on the surface liner paper of the already attached cardboard.

Inkjet printing is a non-contact method of recording images on a printing medium, making it easy to post-print on thick corrugated cardboard, and since the box-making process can begin immediately after printing, it is possible to meet short delivery times. Therefore, demand for inkjet printing in corrugated cardboard printing is on the rise.

Printing on corrugated board has traditionally been done using offset printing, flexography, gravure printing, and other printing methods. However, all of these involve contacting a plate or blanket with the printing medium and applying printing pressure to transfer the ink. As a result, post-printing methods are prone to uneven density due to the unevenness (fluting) of the corrugated board surface, making post-printing particularly difficult on thick corrugated board. On the other hand, while the pre-printing method solves printing issues, it has the problem of requiring a time-consuming lamination process after printing, meaning that the box cannot be made immediately after printing.

When printing on corrugated board, which has a very high water absorption rate, using the inkjet method, it is common to perform pretreatment to prevent ink bleeding, etc. However, if the liquid composition (pretreatment liquid) is applied using analog coating such as roll coating in the pretreatment process, the entire surface is coated, resulting in a lot of liquid loss and high printing costs.On the other hand, if the liquid composition (pretreatment liquid) is applied using digital coating such as the inkjet method, there are issues such as the amount applied being too small and discharge problems such as discharge disturbances.
For example, Patent Document 1 proposes printing by depositing, by an inkjet method, a receiving solution containing one or more surfactants selected from divalent or higher metal salts, silicone surfactants, and acetylene glycol surfactants.
However, the proposal does not disclose anything about the structure of the silicone surfactant, and does not use two types of silicone surfactants in combination, making it difficult to ensure ejection performance while sufficiently suppressing ink bleeding even when a small amount is applied.

The present invention was made in light of this current situation, and aims to provide a liquid composition that can sufficiently suppress ink bleeding even when applied in small amounts, while ensuring ejection performance.

The liquid composition of the present invention as a means for solving the above-mentioned problems contains water, a polyvalent metal salt, a compound represented by the following general formula (I), and a compound represented by the following general formula (II), and the content of the polyvalent metal salt is 15 mass% or more:
In the general formula (I), m represents an integer of 0 or more and 6 or less, and n represents an integer of 2 or more and 19 or less.
In the general formula (II), m represents an integer of 0 or more and 4 or less, and n represents an integer of 3 or more and 15 or less.

This invention makes it possible to provide a liquid composition that can sufficiently suppress ink bleeding while ensuring ejection performance even when applied in small amounts.

FIG. 1 is a schematic diagram showing an example of an image forming apparatus used in the image forming method of the present invention. FIG. 2 is a flowchart showing the image forming method of the present invention. FIG. 3 is a schematic diagram showing an example of the configuration of the control means in the image forming apparatus of the present invention. FIG. 4 is a photograph showing the state of the composition liquid with an ejection stability evaluation of A. FIG. 5 is a photograph showing the state of the composition liquid that was evaluated as B in terms of ejection stability. FIG. 6 is a photograph showing the state of the composition liquid that was evaluated as C in terms of ejection stability. FIG. 7 is a photograph showing the state of the composition liquid that was evaluated as D in terms of ejection stability.

The present invention is described in detail below.

The inventors have conducted extensive research into a liquid composition that can suppress ink bleeding when applied in small amounts while still ensuring ejection performance, and as a result have found that in order to achieve the desired effect when applied in small amounts (including by inkjet methods), it is necessary to add a large amount of polyvalent metal salt. However, when a large amount of polyvalent metal salt is added, the surfactant that helps the liquid composition to sufficiently wet and spread on the substrate begins to separate, making the ejection state from the head extremely unstable.
Furthermore, the addition of a hydrophilic surfactant with a similar structure to the hydrophobic surfactant that ensures the wetting and spreading of the liquid composition and that is well compatible with the system improved the ejection state. Two types of surfactants with similar structures can exist stably in the system by forming mixed micelles with the hydrophobic surfactant on the inside and the hydrophilic surfactant on the outside. It was found that the stable presence of the surfactant in the liquid composition through the above mechanism can stabilize the ejection state of the liquid composition.

In the present invention, it is preferable that the pigment and resin contained in the ink applied after the composition liquid has an anionic charge, as this provides a strong effect in preventing the ink from bleeding.

(composition liquid)
The liquid composition of the present invention contains water, a polyvalent metal salt, a compound represented by the following general formula (I), and a compound represented by the following general formula (II), and may further contain other components as necessary. The liquid composition may also be referred to as a "treatment liquid," a "pre-treatment liquid," a "pre-coating liquid," etc.

In the general formula (I), m represents an integer of 0 or more and 6 or less, and n represents an integer of 2 or more and 19 or less.
In the general formula (II), m represents an integer of 0 or more and 4 or less, and n represents an integer of 3 or more and 15 or less.

<Polyvalent metal salts>
The polyvalent metal salt reacts with the pigment in the ink to quickly aggregate the pigment after the ink is deposited, thereby suppressing color bleeding and improving color development.
Examples of the polyvalent metal compound include titanium compounds, chromium compounds, copper compounds, cobalt compounds, strontium compounds, barium compounds, iron compounds, aluminum compounds, calcium compounds, magnesium compounds, and salts thereof (polyvalent metal salts). These may be used alone or in combination of two or more. Among these, calcium compounds, magnesium compounds, and nickel compounds are preferred because they can effectively aggregate pigments, and alkaline earth metals such as calcium and magnesium are more preferred. The polyvalent metal compound is preferably ionic. In particular, when the polyvalent metal compound is a calcium salt, the stability of the reaction solution is improved.
Examples of the polyvalent metal salt include calcium carbonate, calcium nitrate, calcium chloride, calcium acetate, calcium sulfate, magnesium chloride, magnesium acetate, magnesium sulfate, barium sulfate, zinc sulfide, zinc carbonate, aluminum lactate, aluminum silicate, calcium silicate, magnesium silicate, and aluminum hydroxide. These may be used alone or in combination of two or more. Among these, magnesium acetate, calcium nitrate, and aluminum lactate are preferred.

The polyvalent metal salt must be present in an amount of 15% by mass or more of the total liquid composition in order to obtain a bleed-free image even on highly absorbent substrates, and preferably 20% by mass or more in order to obtain a more bleed-free image or to be compatible with a variety of substrates.

<<Compounds Represented by General Formula (I) and General Formula (II)>>
The liquid composition of the present invention contains a compound represented by the following general formula (I) and a compound represented by the following general formula (II): While the purpose of adding these compounds is not particularly limited, the addition of the compound represented by the general formula (I) significantly improves the wettability of the liquid composition to a substrate, and the addition of the compound represented by the general formula (II) ensures ejection stability when a large amount of polyvalent metal salt is added.

In the general formula (I), m represents an integer of 0 or more and 6 or less, and n represents an integer of 2 or more and 19 or less.
In the general formula (II), m represents an integer of 0 or more and 4 or less, and n represents an integer of 3 or more and 15 or less.
In the compound of the general formula (I) and the general formula (II), all terminals extending from silicon, unless otherwise specified, are methyl groups.
The compound represented by the general formula (I) suppresses ink bleeding in the surface direction of the recording medium, and the compound represented by the general formula (II) suppresses ink bleeding in the depth direction of the recording medium. Since the compound represented by the general formula (I) alone cannot suppress ink bleeding in the depth direction, and the compound represented by the general formula (II) alone cannot suppress ink bleeding in the surface direction, by containing both, ink bleeding can be efficiently suppressed in both the surface direction and the depth direction, and an ink bleeding suppression effect can be obtained even with a small amount of application.
Therefore, when the mass ratio of the compound represented by the general formula (I) to the compound represented by the general formula (II) is 1:2 to 1:4, the applied composition liquid spreads particularly uniformly, thereby suppressing color bleeding. This is particularly preferable because it enables printing on various absorbent recording media and provides stable ejection.
The content of the compound represented by the general formula (I) and the compound represented by the general formula (II) is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less, based on the total amount of the composition liquid.

The compound represented by the general formula (I) and the compound represented by the general formula (II) may be commercially available products or may be appropriately synthesized.
Commercially available products of the compound represented by the general formula (I) include, for example, WET-270 and WET-280 (manufactured by Evonik), and SAG-002 (manufactured by Nissin Chemical Industry Co., Ltd.). Commercially available products of the compound represented by the general formula (II) include, for example, WET-240 (manufactured by Evonik), BYK-345, and BYK-348 (manufactured by BYK-Chemie).
The synthesis method of the compound represented by the general formula (I) and the compound represented by the general formula (II) is not particularly limited and can be appropriately selected depending on the purpose, and reference can be made to the descriptions in, for example, Japanese Patent No. 5101598, Japanese Patent No. 5032325, and Japanese Patent No. 5661229. Specifically, the compounds can be synthesized by subjecting (A) a polyether and (B) an organohydrogensiloxane to a hydrosilylation reaction.

<<Method for analyzing the structure of general formula (I) and general formula (II)>>
The structures of the compounds represented by the general formula (I) and the general formula (II) can be confirmed by IR or NMR. The weight average molecular weight and n of the compound represented by the general formula (I) can be measured using the following apparatus and conditions.

Analyzer: Mass spectrometer (MALDI-TOFMS Bruker Daltonics, autoflex III)
- Preparation of sample solution -
The compound to be evaluated is dissolved in methanol to a concentration of 1,000 ppm.
- Preparation of matrix solution -
A 10 mg/mL 2,5-dihydroxybenzoic acid (DHB) TA solution was prepared by mixing a 0.1% by mass aqueous solution of trifluoroacetic acid and acetonitrile in a 2:1 (volume ratio).
-Preparing the measurement solution-
The sample solution, matrix solution, and saturated ethanol solution of NaCl are mixed in a volume ratio of 1:4:1.
-Measurement method-
1 μL of the measurement solution is dropped onto a MALDI plate, dried, and then subjected to MALDI measurement.
Detected ion: cation Furthermore, the abundance ratio of the general formulae (I) and (II) can be calculated from the peak intensity ratio of the MALDI-TOF mass spectrum of a calibration curve standard solution in which the general formulae (I) and (II) are mixed and the composition solution after obtaining a specimen, or can be quantified from the area value of the calibration curve standard solution of the general formulae (I) and (II) and the composition solution using a liquid chromatography analysis method under analysis conditions that allow the components of the general formulae (I) and (II) to be quantified.

<<Organic solvents>>
The liquid composition of the present invention may further contain a separate organic solvent, if necessary.
The organic solvent used in the present invention is not particularly limited, and any water-soluble organic solvent can be used, including, for example, polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, and 1,4-pentanediol. Examples of such hexanediol include 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol.
Examples of polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether.
Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone.
Examples of amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide.
Examples of the amines include monoethanolamine, diethanolamine, and triethylamine.
Examples of sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol.
Other organic solvents include propylene carbonate and ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250° C. or less, since it not only functions as a wetting agent but also provides good drying properties.
In particular, from the viewpoint of ensuring ejection stability from an inkjet head, it is preferable to contain at least one polyhydric alcohol, and it is particularly preferable to use any one of 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol.

<Water>
As the water, for example, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water can be used.
The water content in the ink is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of the drying properties and ejection reliability of the ink, however, the water content is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass to 60% by mass.

<<Other additives>>
The liquid composition of the present invention may contain other additives such as an antifoaming agent, an antiseptic/fungal agent, and an antirust agent.

<<Antifoaming agent>>
The defoaming agent is not particularly limited, and examples thereof include silicone-based defoaming agents, polyether-based defoaming agents, and fatty acid ester-based defoaming agents. These may be used alone or in combination of two or more. Among these, silicone-based defoaming agents are preferred because of their excellent foam-breaking effect.

＜＜Preservative and fungicide＞＞
The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<<Rust inhibitor>>
The rust inhibitor is not particularly limited, and examples thereof include acid sulfites and sodium thiosulfate.

The liquid composition of the present invention can be prepared by adding the above-mentioned components to an aqueous solvent and, if necessary, stirring and mixing. Stirring and mixing can be performed using a mixer with a conventional stirring blade, a magnetic stirrer, a high-speed disperser, etc.

(Ink and liquid composition set)
The ink and liquid composition set of the present invention includes an ink containing a pigment and a resin, and the liquid composition of the present invention.

<Ink>
The organic solvent, water, coloring material, resin, additives, etc. used in the ink will be described below.

<<Organic solvents>>
The organic solvent used in the present invention is not particularly limited, and any water-soluble organic solvent can be used, including, for example, polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, and 1,4-pentanediol. , 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, petriol, and the like.
Examples of polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether.
Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone.
Examples of amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide.
Examples of the amines include monoethanolamine, diethanolamine, and triethylamine.
Examples of sulfur-containing compounds include dimethyl sulfoxide, sulfolane, and thiodiethanol.
Other organic solvents include propylene carbonate and ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250° C. or less, since it not only functions as a wetting agent but also provides good drying properties.

As the organic solvent, polyol compounds having 8 or more carbon atoms and glycol ether compounds are also suitably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of glycol ether compounds include polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Polyol compounds having 8 or more carbon atoms and glycol ether compounds can improve the permeability of ink when paper is used as the recording medium.

There are no particular restrictions on the content of organic solvent in the ink and it can be selected appropriately depending on the purpose. However, from the viewpoint of the drying properties and ejection reliability of the ink, it is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

＜＜Water＞＞
The water content in the ink is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of the drying property and ejection reliability of the ink, however, the water content is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

<<Colorants>>
The coloring material is not particularly limited, and pigments and dyes can be used.
The pigment may be an inorganic pigment or an organic pigment. These may be used alone or in combination of two or more. Mixed crystals may also be used as the pigment.
Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments.
As inorganic pigments, titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used.
In addition, examples of organic pigments that can be used include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments), dye chelates (e.g., basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, and aniline black. Of these pigments, those with good affinity for the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
Specific examples of pigments for black include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron (C.I. Pigment Black 11), and titanium oxide; and organic pigments such as aniline black (C.I. Pigment Black 1).
Furthermore, for color, C.I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101 (Red Iron), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38, C.I. Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63, C.I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.

The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone, or two or more types may be used in combination.
Examples of dyes include C.I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. Acid Red 52, 80, 82, 249, 254, 289, C.I. Acid Blue 9, 45, 249, C.I. Acid Black 1, 2, 24, 94, C.I. Food Black 1, 2, C.I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. Direct Red 1, 4, 9, 80, 81, 225, 227, C.I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. Reactive Red 14, 32, 55, 79, 249, C.I. Reactive Black 3, 4, 35, etc.

The content of colorant in the ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, from the viewpoints of improving image density, good fixation, and ejection stability.

Methods for dispersing a pigment to obtain an ink include a method of introducing a hydrophilic functional group into a pigment to make it a self-dispersing pigment, a method of dispersing the pigment by coating the surface of the pigment with a resin, and a method of dispersing the pigment using a dispersant.
As a method for introducing a hydrophilic functional group into a pigment to make it a self-dispersible pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (e.g., carbon) to make it dispersible in water can be mentioned.
One method for dispersing a pigment by coating its surface with a resin is to encapsulate the pigment in microcapsules to make it dispersible in water. This can be rephrased as a resin-coated pigment. In this case, it is not necessary for all of the pigments blended into the ink to be coated with resin; uncoated or partially coated pigments may be dispersed in the ink, provided that the effects of the present invention are not impaired.
Examples of the method for dispersing using a dispersant include a method for dispersing using a known low molecular weight dispersant or a high molecular weight dispersant, such as a surfactant.
As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used depending on the pigment.
As the dispersant, RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used.
The dispersants may be used alone or in combination of two or more.

<<Pigment dispersion>>
Ink can be obtained by mixing a pigment with water, an organic solvent, or other materials. Alternatively, ink can be produced by mixing a pigment with other materials such as water and a dispersant to form a pigment dispersion, and then mixing the resulting mixture with water, an organic solvent, or other materials.
The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and optionally other components, and adjusting the particle size. Dispersion is preferably performed using a disperser.
Although there are no particular restrictions on the particle size of the pigment in the pigment dispersion, the maximum frequency, calculated as the maximum number, is preferably 20 nm or more and 500 nm or less, and more preferably 20 nm or more and 150 nm or less, in order to improve the dispersion stability of the pigment and to enhance the image quality such as ejection stability and image density. The particle size of the pigment can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of obtaining good ejection stability and increasing image density, the content is preferably 0.1% by mass or more and 50% by mass or less, and more preferably 0.1% by mass or more and 30% by mass or less.
It is preferable to filter out coarse particles from the pigment dispersion using a filter, a centrifugal separator or the like, and degas the dispersion, if necessary.

<<Resin>>
The type of resin contained in the ink is not particularly limited and can be appropriately selected depending on the purpose. Examples include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic styrene resin, and acrylic silicone resin.
Resin particles made of these resins may also be used. The resin particles may be dispersed in water as a dispersion medium to form a resin emulsion, which may be mixed with materials such as a coloring material and an organic solvent to obtain an ink. The resin particles may be appropriately synthesized or commercially available. These may be used alone or in combination of two or more types of resin particles.

The volume average particle size of the resin particles is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of obtaining good fixing properties and high image hardness, the volume average particle size is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 100 nm or less.
The volume average particle size can be measured, for example, using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

There are no particular restrictions on the resin content, and it can be selected appropriately depending on the purpose. However, from the standpoint of fixation and ink storage stability, it is preferably 1% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, of the total amount of ink.

There are no particular restrictions on the particle size of the solids in the ink, and it can be selected appropriately depending on the purpose. To improve image quality, such as ejection stability and image density, the maximum frequency of particle sizes of the solids in the ink, calculated in terms of maximum number, is preferably 20 nm or more and 1000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solids include resin particles, pigment particles, etc. Particle size can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

It is particularly preferable that the pigment and resin have an anionic charge and are dispersed in the system, as this provides excellent reactivity with the polyvalent metal salt contained in the liquid composition, thereby efficiently preventing image bleeding.

<<Additives>>
If necessary, surfactants, antifoaming agents, antiseptic and antifungal agents, rust inhibitors, pH adjusters, etc. may be added to the ink.

<<Surfactants>>
As the surfactant, any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants and anionic surfactants can be used.
The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Among them, those that do not decompose even at high pH are preferred. Examples of silicone surfactants include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end modified polydimethylsiloxane of the side chain. Those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as the modifying group are particularly preferred because they exhibit good properties as aqueous surfactants. Furthermore, polyether-modified silicone surfactants can also be used as silicone surfactants, and examples thereof include compounds in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane.
As fluorine-based surfactants, for example, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chain are particularly preferred because of their low foaming properties. Examples of perfluoroalkyl sulfonic acid compounds include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate salts. Examples of perfluoroalkyl carboxylic acid compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylate salts. Examples of polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chain include sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups on the side chain, and salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups on the side chain. Counter ions of _the salts in these fluorine-based surfactants include _Li , Na, K _{, NH4} , _NH3CH2CH2OH , _{NH2 ( CH2CH2OH} ) ₂ , NH( _CH2CH2OH ) ₃ , and the like.
Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohol.
Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzenesulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates.
These may be used alone or in combination of two or more.

The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include side-chain-modified polydimethylsiloxane, both-end-modified polydimethylsiloxane, one-end-modified polydimethylsiloxane, and both-end-modified side-chain polydimethylsiloxane. Polyether-modified silicone surfactants having polyoxyethylene groups or polyoxyethylene-polyoxypropylene groups as modifying groups are particularly preferred because they exhibit good properties as aqueous surfactants.
Such surfactants may be synthesized appropriately or commercially available products, such as those available from BYK Corporation, Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.
The polyether-modified silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include surfactants represented by general formula (S-1), in which a polyalkylene oxide structure is introduced into the Si moiety side chain of dimethylpolysiloxane.

(In the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R′ represents an alkyl group.)
As the polyether-modified silicone surfactant, commercially available products can be used, and examples thereof include KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX (Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Dow Corning Toray Silicone Co., Ltd.), BYK-33, BYK-387 (BYK-Chemie Co., Ltd.), TSF4440, TSF4452 (Nichisyo Sangyo Co., Ltd.), and the like.

As the fluorine-based surfactant, a compound having 2 to 16 fluorine-substituted carbon atoms is preferred, and a compound having 4 to 16 fluorine-substituted carbon atoms is more preferred.
Examples of fluorine-based surfactants include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group on the side chain. Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group on the side chain are preferred because they have low foaming properties, and fluorine-based surfactants represented by general formula (F-1) and general formula (F-2) are particularly preferred.

In the compound represented by the above general formula (F-1), m is preferably an integer of 0 to 10, and n is preferably an integer of 0 to 40 in order to impart water solubility.

In the compound represented by the general formula (F-2), Y is H, or C _m F _2m+1 where m is an integer from 1 to 6, or CH ₂ CH(OH)CH ₂ -C _m F _2m+1 where m is an integer from 4 to 6, or C _p H _2p+1 where p is an integer from 1 to 19. n is an integer from 1 to 6. a is an integer from 4 to 14.

Commercially available fluorine-based surfactants may be used. Examples of such commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, and FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F-1405, and F-474 (all manufactured by DIC Corporation); and Zonyl TBS, FSP, FSA, FSN-100, and FS N, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours Corporation); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Corporation), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (all manufactured by Omnova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), and the like. Among these, Chemours FS-3100, FS-34, and FS-300, Neos FT-110, FT-250, FT-251, FT-400S, FT-150, and FT-400SW, Omnova Polyfox PF-151N, and Daikin Industries, Ltd. Unidyne DSN-403N are particularly preferred because they provide excellent print quality, particularly improved color development, paper penetration, wettability, and dye leveling.

There are no particular restrictions on the content of surfactant in the ink and it can be selected appropriately depending on the purpose, but from the viewpoint of achieving excellent wettability and ejection stability as well as improved image quality, a content of 0.001% by mass or more and 5% by mass or less is preferred, and 0.05% by mass or more and 5% by mass or less is even more preferred.

As for other ingredients, those used in the above composition solution can be suitably used.

(Image forming apparatus and image forming method)
The image forming method of the present invention includes a liquid composition application step of applying the liquid composition of the present invention to an absorbent recording medium, and preferably includes an ink application step of applying an ink containing a pigment and a resin to the absorbent recording medium to which the liquid composition has been applied, and may further include other steps as necessary.

The ink and treatment liquid set of the present invention can be suitably used in various ink jet recording devices, such as printers, facsimile machines, copying machines, printer/fax/copier combination machines, and three-dimensional modeling devices.
In the present invention, the image forming apparatus and image forming method refer to an apparatus capable of ejecting ink, various treatment liquids, etc. onto a recording medium, and a method of recording using such an apparatus. The recording medium refers to a medium to which ink or various treatment liquids can be applied, even temporarily. Furthermore, this recording apparatus also includes desktop image forming apparatuses and wide-format image forming apparatuses capable of printing on A0-size recording media, such as continuous feed printers that can use continuous paper wound into a roll as the recording medium.

FIG. 1 shows an example of an image forming apparatus.
In the image forming method of the present invention, the step of applying the ink and the step of applying the pretreatment liquid may be carried out by the same printing machine, or may be carried out by different printing machines.

1 includes a liquid composition (pretreatment liquid) applying unit 110, an ink applying unit 120, a control unit 160, and a storage unit 170, and may also include a post-treatment liquid applying unit 130, a drying unit 140, and a transport unit 150, as necessary. The liquid composition (pretreatment liquid) applying unit 110 applies a liquid composition (pretreatment liquid) to a recording medium M.
Any known method can be used without any particular limitation as the coating method in the composition liquid (pretreatment liquid) application unit 110. Examples include inkjet coating, blade coating, gravure coating, gravure offset coating, bar coating, roll coating, knife coating, air knife coating, comma coating, U comma coating, AKKU coating, smoothing coating, microgravure coating, reverse roll coating, four-roll coating, five-roll coating, dip coating, curtain coating, slide coating, and die coating. Of these, inkjet coating is particularly preferred from the viewpoint of uniformly applying a small amount of liquid to a desired location.

The ink application unit 120 applies inkjet ink to the surface of the recording medium M to which the composition liquid (pretreatment liquid) has been applied.
As the ink applying unit 120, for example, a known inkjet head can be used.
The ink application unit 120 may be a head that ejects ink of any color, and for example, a head that ejects ink of the colors Y (yellow), M (magenta), C (cyan), K (black), and W (white) may be provided as needed.

The storage unit 170 is, for example, a HDD, and stores data such as images to be printed, etc. The control means 160 of the image forming apparatus is, for example, a CPU, and issues instructions to the storage unit 170 and each control unit.
The composition liquid deposition control unit 161 controls the driving of the composition liquid deposition unit 110 in response to instructions from the control means 160 .
The ink application control unit 162 controls the driving of the ink application unit 120 in response to instructions from the control means 160 .
The drying control unit 163 controls the driving of the drying unit 140 in response to instructions from the control means 160 .

The post-treatment liquid application unit 130 is only required to be able to apply the post-treatment liquid to the area on the surface of the recording medium M to which the inkjet ink has been applied, and for example, in addition to an inkjet head, a spray, a roller, or the like can be used.
The post-treatment liquid application unit 130 may be omitted.

The method for applying the post-treatment liquid is not particularly limited, but examples include inkjet coating, roller coating, blade coating, gravure coating, gravure offset coating, bar coating, roll coating, knife coating, air knife coating, comma coating, U-comma coating, AKKU coating, smoothing coating, microgravure coating, reverse roll coating, four- or five-roll coating, dip coating, curtain coating, slide coating, and die coating.

The image forming apparatus of the present invention may have a drying section 140 that dries the recording medium M to which the composition liquid (pretreatment liquid) and ink have been applied. If necessary, a drying step may be included after the application of other liquids, including a posttreatment liquid, or before or after the application of each liquid. Many known devices can be used for heating. Examples include devices using hot air heating, radiant heating, conduction heating, high-frequency drying, microwave drying, and fixing rollers. These may be used alone or in combination of two or more. The drying intensity is preferably set according to the thermal shrinkage characteristics, such as the thickness and material of the substrate. Since efficient removal of volatile components after ink deposition further improves the setting properties of the image, it is preferable to use at least one of hot air drying and IR drying in the drying process.
The drying section 140 may be omitted.

The conveying section 150 conveys the recording medium M.
The conveying unit 150 is not particularly limited as long as it is capable of conveying the recording medium M, but examples thereof include a conveying belt and a platen.
The transport unit 150 may be omitted if necessary.

When a desktop printer is used as an image forming apparatus, one embodiment of the pre-treatment liquid application unit and post-treatment liquid application unit is to add a liquid storage unit containing the pre-treatment liquid or post-treatment liquid and a liquid ejection head, and eject the pre-treatment liquid or post-treatment liquid using an inkjet recording method, as in the case of inks such as black (K), cyan (C), magenta (M), yellow (Y), and white (W).

<Example of Operation of Image Forming Apparatus 100>
The operation of the image forming apparatus 100 will now be described with reference to a flowchart shown in FIG.

When the image forming device 100 receives an instruction to start image formation, it begins image formation operations.

In step S1, the transport unit 150 of the image forming apparatus 100 transports the recording medium M, and the composition liquid deposition unit 110 deposits the composition liquid onto the recording medium M. At this time, the composition liquid deposition unit 110 may deposit the composition liquid only onto the portion where an image is to be formed, or may deposit the composition liquid onto the entire surface of the recording medium.
When the composition liquid application unit 110 applies the composition liquid only to the area where an image is to be formed, the application range is determined in accordance with instructions from the composition liquid application control unit 161 or the control means 160, and the composition liquid is applied to the recording medium M.
When the composition liquid application unit 110 applies the composition liquid to the entire surface of the recording medium, the composition liquid is applied to the entire surface of the recording medium in accordance with instructions from the composition liquid application control unit 161 or the control means 160 .

In step S2, the ink applying unit 120 ejects ink onto the recording medium M that has been conveyed by the conveying unit 150 and onto which the composition liquid has been applied. At this time, the ink applying unit 120 may eject ink only onto the portion onto which the composition liquid has been ejected, or onto the entire surface of the recording medium. However, in the present invention, it is preferable that the ink applying unit 120 ejects ink onto the portion onto which the composition liquid has been applied.
When ink is ejected only onto the portion where an image is to be formed, the ejection range is determined in accordance with instructions from the ink application control unit 162 or the control means 160, and the ink application unit 120 ejects the ink.
When the ink application unit 120 ejects ink onto the entire surface of the recording medium, the ink is ejected onto the entire surface of the recording medium in accordance with instructions from the ink application control unit 162 and the control means 160 .

The image forming apparatus 100 may be provided with a sensor that recognizes the position and location of the recording medium. By providing such a sensor that recognizes the position and location of the recording medium, the liquid composition application unit 110 and the ink application unit 120 can more efficiently apply the liquid composition and ink to the recording medium in steps S1 and S2.

In step S3, the recording medium coated with the composition liquid and ink is transported by the transport unit 150 to the drying unit 140, where it is dried. Step S3 and the drying unit 140 are not essential for the image forming method and image forming apparatus of the present invention, but are more preferably included.
The drying time and drying temperature may be constant or may be adjusted depending on the amounts of the liquid composition and ink applied, and are more preferably adjusted depending on the amounts of the liquid composition and ink applied.
When adjusting the drying time or drying temperature, the drying time or drying temperature is determined in accordance with instructions from the drying control unit 163 or the control means 160, and the recording medium is dried.
When the drying time and drying temperature are constant, the recording medium is dried in accordance with instructions from the drying control unit 163 and the control means 160 .

The image forming apparatus 100 may be provided with a sensor that recognizes the amount of the liquid composition and ink applied to the recording medium. By providing the sensor, it becomes possible to set and adjust the drying time and drying temperature according to the amount of the liquid composition and ink applied to the recording medium, allowing the drying unit 140 to dry the recording medium more efficiently in step S3.
The sensor that recognizes the amount of applied liquid composition and ink may be one that recognizes the amount of liquid actually attached to the recording medium, or may be one that measures and recognizes the amount ejected onto the recording medium at each application unit.

After the recording medium has been dried, the image formation process using the image forming device is complete, but if necessary, there may be a step of removing the recording medium from the image forming device or a step of transporting the recording medium.

<<Recording Media>>
The recording medium used for recording in the present invention is not particularly limited, and can be plain paper, glossy paper, special paper, cloth, film, OHP sheet, general-purpose printing paper, etc., but the liquid composition, ink and liquid composition set, and image forming method of the present invention are particularly effective on absorbent recording media. Absorbent recording media refer to recording media that are permeable to the liquid composition or ink, and include, for example, plain paper, general-purpose printing paper, cardboard, and fabric. In the configuration of the present invention, particularly high-quality recordings can be obtained when cardboard (liner paper) is used.
Fiber materials used in the manufacture of liner paper include bleached hardwood or softwood kraft pulp, unbleached hardwood or softwood kraft pulp, sulfite hardwood or softwood pulp, etc. Also usable are chemically treated pulp, pulp chemically treated using kenaf, hemp, reed, etc., virgin pulp such as ground pulp, chemi-ground pulp, and semi-chemical pulp, and recycled paper such as cardboard, newspapers, magazines, and flyers.

In addition, in the present invention, the terms image formation, recording, printing, printing, etc. are all synonymous.
Recording medium, media, and printed material are all synonymous terms.

The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to these examples.

(Preparation Examples 1 to 14 of Composition Solutions)
- Preparation of composition solutions 1 to 14 -
The compositions and amounts shown in Tables 1 and 2 were mixed and stirred, and filtered through a polypropylene filter with an average pore size of 0.2 μm to prepare composition solutions 1 to 14.

The materials used in Tables 1 and 2 are as follows:
Compound (1)-1: In the above general formula (I), m = 0, n = 2 to 18 (manufactured by Nissin Chemical Industry Co., Ltd., Silface SAG-002)
Compound (1)-2: In the above general formula (I), m=2, n=3 to 14 (manufactured by Evonik, TEGO WET-270)
Compound (1)-3: In the above general formula (I), m=7, n=5 to 20 (Synthesis Example 1)
Compound (2)-1: In the above general formula (II), m = 0 to 4, n = 3 to 15 (manufactured by Nissin Chemical Industry Co., Ltd., Silface SAG-503A)
Compound (2)-2: In the above general formula (II), m = 2 to 4, n = 4 to 12 (BYK-348, manufactured by BYK-Chemie Corporation)
Compound (2)-3: In the above general formula (II), m = 5, n = 2 to 17 (Synthesis Example 2)
Proxel LV (manufactured by Avecia)

The synthesis methods of Synthesis Examples 1 and 2 are shown below.
<Synthesis Example 1>
A five-neck flask equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube was charged with 450 parts by mass of allylated polyether (UNIOX PKA-5008, manufactured by NOF Corporation) and 0.01 parts by mass of H ₂ PtCl _{6.6H 2} O hexachloroplatinic (IV) acid hexahydrate (manufactured by Tokyo Chemical Industry Co., Ltd.), and nitrogen substitution was performed. The mixture was heated to 70 ° C., and 220 parts by mass of heptamethyltrisiloxane (manufactured by Aldrich) was added dropwise over 1 hour, after which the reaction vessel was heated to 110 ° C. and reacted for 4 hours. After the reaction, unreacted materials were distilled off under reduced pressure to obtain compound (1)-3.

<Synthesis Example 2>
Compound (2)-3 was obtained in the same manner as in Synthesis Example 1, except that 200 parts by mass of an allylated polyether (UNIOX PKA-5001, manufactured by NOF Corporation) was used instead of 450 parts by mass of the allylated polyether (UNIOX PKA-5008, manufactured by NOF Corporation).

(Ink Set Preparation Example 1)
<Preparation of Black Ink 1>
Carbon black was premixed in the following mixing ratio, and then circulated and dispersed for 7 hours in a disk-type bead mill (KDL model, manufactured by Shinmaru Enterprises Co., Ltd., media: zirconia balls with a diameter of 0.3 mm) to obtain black pigment dispersion K1.
Carbon black (manufactured by Tokai Carbon Co., Ltd., SEAEST SP (SRF-LS)): 15 parts by mass Anionic surfactant (manufactured by Takemoto Oil & Fat Co., Ltd., Pionin A-51-B): 2 parts by mass Ion-exchanged water: 83 parts by mass

Next, the compositions and amounts were mixed and stirred, and filtered through a 0.2 μm polypropylene filter to obtain black ink 1.
Black pigment dispersion K1: 20 parts by mass Superflex 460 (anionic urethane dispersion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 15 parts by mass Softanol EP-5035 (manufactured by Nippon Shokubai Co., Ltd.): 2 parts by mass 1,2-propanediol: 20 parts by mass Diethylene glycol n-butyl ether: 10 parts by mass Antiseptic and antifungal agent Proxel LV (manufactured by Avecia): 0.1 parts by mass Ion-exchanged water: 32.9 parts by mass

<Preparation of Cyan Ink 1>
Pigment Blue 15:3 was premixed in the following mixing ratio, and then circulated and dispersed for 7 hours in a disk-type bead mill (manufactured by Shinmaru Enterprises Co., Ltd., KDL model, media: zirconia balls with a diameter of 0.3 mm) to obtain cyan pigment dispersion C1.
Pigment Blue 15:3 (Dainichiseika Color & Chemicals Mfg. Co., Ltd., Chromofine A-220JC): 15 parts by mass; Anionic surfactant (Takemoto Yushi Co., Ltd., Paionin A-51-B): 2 parts by mass; Ion-exchanged water: 83 parts by mass

Next, the compositions and amounts were mixed and stirred, and filtered through a 0.2 μm polypropylene filter to obtain cyan ink 1.
Cyan pigment dispersion C1: 20 parts by mass Superflex 460 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., anionic urethane dispersion): 15 parts by mass Softanol EP-5035 (manufactured by Nippon Shokubai Co., Ltd.): 2 parts by mass 1,2-propanediol: 20 parts by mass Diethylene glycol n-butyl ether: 10 parts by mass Antiseptic and antifungal agent Proxel LV (manufactured by Avecia): 0.1 parts by mass Ion-exchanged water: 32.9 parts by mass

<Preparation of Magenta Ink 1>
Pigment Red 122 was premixed in the following mixing ratio, and then circulated and dispersed for 7 hours in a disk-type bead mill (manufactured by Shinmaru Enterprises Co., Ltd., KDL model, media: zirconia balls with a diameter of 0.3 mm) to obtain Magenta Pigment Dispersion M1.
Pigment Red 122 (manufactured by BASF, Cinquasia Magenta D4550J): 15 parts by mass; Anionic surfactant (manufactured by Takemoto Oil & Fat Co., Ltd., Paionin A-51-B): 2 parts by mass; Ion-exchanged water: 83 parts by mass

Next, the compositions and blending amounts were mixed and stirred, and filtered through a 0.2 μm polypropylene filter to obtain magenta ink 1.
Magenta pigment dispersion M1: 20 parts by mass Superflex 460 (anionic urethane dispersion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 15 parts by mass Softanol EP-5035 (manufactured by Nippon Shokubai Co., Ltd.): 2 parts by mass 1,2-propanediol: 20 parts by mass Diethylene glycol n-butyl ether: 10 parts by mass Antiseptic and antifungal agent Proxel LV (manufactured by Avecia): 0.1 parts by mass Ion-exchanged water: 32.9 parts by mass

<Preparation of Yellow Ink 1>
Pigment Yellow 74 was premixed in the following mixing ratio, and then circulated and dispersed for 7 hours in a disk-type bead mill (KDL model, manufactured by Shinmaru Enterprises Co., Ltd., media: zirconia balls with a diameter of 0.3 mm) to obtain Yellow Pigment Dispersion Y1.
Pigment Yellow 74 (Seika First 6270AJC, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.): 15 parts by mass; Anionic surfactant (Paionin A-51-B, manufactured by Takemoto Oil & Fat Co., Ltd.): 2 parts by mass; Ion-exchanged water: 83 parts by mass

Next, the compositions and amounts were mixed and stirred, and filtered through a 0.2 μm polypropylene filter to obtain Yellow Ink 1.
Yellow pigment dispersion Y1: 20 parts by mass Superflex 460 (anionic urethane dispersion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 15 parts by mass Softanol EP-5035 (manufactured by Nippon Shokubai Co., Ltd.): 2 parts by mass 1,2-propanediol: 20 parts by mass Diethylene glycol n-butyl ether: 10 parts by mass Antiseptic and antifungal agent Proxel LV (manufactured by Avecia): 0.1 parts by mass Ion-exchanged water: 32.9 parts by mass

As a result of the above, ink set 1 consisting of black ink 1, cyan ink 1, magenta ink 1, and yellow ink 1 was prepared.

(Ink Set Preparation Example 2)
-Method of preparing ink set 2-
Black pigment dispersion K2 was obtained in the same manner as in preparation of black pigment dispersion K1, except that a nonionic surfactant (Disparlon DN-900, manufactured by Kusumoto Chemicals Co., Ltd.) was used as the dispersant instead of the anionic surfactant (Paionin A-51-B, manufactured by Takemoto Yushi Co., Ltd.).
For cyan, magenta, and yellow, pigment dispersions of each color (C2 to Y2) were prepared in the same manner as in the preparation of black pigment dispersion K2, except that the pigment type was changed.
Thereafter, the following blending amounts were mixed and stirred with Black Pigment Dispersion K2, and filtered through a 0.2 μm polypropylene filter to obtain Black Ink 2.
Black pigment dispersion K2: 20 parts by mass Superflex 460 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., anionic urethane dispersion): 15 parts by mass Softanol EP-5035 (manufactured by Nippon Shokubai Co., Ltd.): 2 parts by mass 1,2-propanediol: 20 parts by mass Diethylene glycol n-butyl ether: 10 parts by mass Antiseptic and antifungal agent Proxel LV (manufactured by Avecia): 0.1 parts by mass Ion-exchanged water: 32.9 parts by mass The preparation of the cyan ink, magenta ink, and yellow ink was carried out in the same manner as for black ink 2, except that the pigment dispersions were changed to C2 to Y2, and ink set 2 consisting of black ink 2, cyan ink 2, magenta ink 2, and yellow ink 2 was prepared.

(Ink Set Preparation Example 3)
<Method of preparing ink set 3>
Black ink 3 was obtained by mixing and stirring the following blending amounts using the black pigment dispersion K1 used in preparing black ink 1 and filtering through a 0.2 μm polypropylene filter.
Black pigment dispersion K1: 20 parts by mass Superflex 500M (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., nonionic urethane dispersion): 15 parts by mass Softanol EP-5035 (manufactured by Nippon Shokubai Co., Ltd.): 2 parts by mass 1,2-propanediol: 20 parts by mass Diethylene glycol n-butyl ether: 10 parts by mass Antiseptic and antifungal agent Proxel LV (manufactured by Avecia): 0.1 parts by mass Ion-exchanged water: 32.9 parts by mass The preparation of the cyan ink, magenta ink, and yellow ink was carried out in the same manner as for black ink 3, except that the pigment dispersions were changed to C1 to Y1, and ink set 3 consisting of black ink 3, cyan ink 3, magenta ink 3, and yellow ink 3 was prepared.

(Ink Set Preparation Example 4)
<Method of preparing ink set 4>
Black ink 4 was obtained by mixing and stirring the following blending amounts using the black pigment dispersion K2 used in preparing black ink 2 and filtering through a 0.2 μm polypropylene filter.
Black pigment dispersion K2: 20 parts by mass Superflex 500M (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., nonionic urethane dispersion): 15 parts by mass Softanol EP-5035 (manufactured by Nippon Shokubai Co., Ltd.): 2 parts by mass 1,2-propanediol: 20 parts by mass Diethylene glycol n-butyl ether: 10 parts by mass Antiseptic and antifungal agent Proxel LV (manufactured by Avecia): 0.1 parts by mass Ion-exchanged water: 32.9 parts by mass The preparation of the cyan ink, magenta ink, and yellow ink was carried out in the same manner as for black ink 4, except that the pigment dispersions were changed to C2 to Y2, and ink set 4 consisting of black ink 4, cyan ink 4, magenta ink 4, and yellow ink 4 was prepared.

(Examples 1 to 11 and Comparative Examples 1 to 6)
Next, images were formed using the combinations of liquid compositions and ink sets shown in Tables 3 and 4, and evaluations were carried out as follows. The evaluation results are shown in Tables 3 and 4.

<Color boundary bleeding evaluation 1>
A modified inkjet printer (device name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.) filled with each of the prepared liquid compositions was prepared, and the ink was applied to cardboard liner paper (product name: NPK Liner TF, manufactured by Nippon Paper Industries Co., Ltd.). Thereafter, each of the prepared ink sets was filled into another inkjet printer (device name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.), and printing was performed on the liner paper. The color boundary bleeding of the obtained image was visually evaluated according to the following evaluation criteria. Note that a grade of B or higher is a practical level.
[Evaluation criteria]
A: No color bleeding at all at any color boundary B: Slight bleeding is observed between some colors C: Slight bleeding is observed between most colors D: Severe bleeding is observed, degrading image quality

<Color boundary bleeding evaluation 2>
Except for changing the printing substrate in the above Color Boundary Bleeding Evaluation 1 to a cardboard liner paper (product name: NPKG, manufactured by Nippon Paper Industries Co., Ltd.), color boundary bleeding of the image was evaluated in the same manner as in the above Color Boundary Bleeding Evaluation 1. The evaluation criteria were also the same as those in the above Color Boundary Bleeding Evaluation 1.
The substrates used in the evaluation of the above two types of color boundary bleeding have different water absorbencies, with Cobb water absorbencies according to JIS P 8140 being NPK liner TF: 56 g/m ² and NPKF: 27 g/m ² (contact time of 120 seconds in both cases).
The test was carried out on two types of substrates, as substrates with good water absorption may cause the liquid composition to be absorbed into the substrate, preventing the liquid composition from working properly and resulting in ink bleeding, while substrates with poor water absorption may cause the ink to remain on the surface for a long time, resulting in bleeding.
Therefore, the fact that good image quality can be obtained with both indicates that good image quality can be obtained regardless of the substrate.

<Evaluation of ejection stability>
A dye (Food Blue No. 1, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to each composition liquid to color it, and the liquid was filled into an inkjet printer (device name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.). A chart with dots arranged every other nozzle was printed on plain paper (product name: My Paper, manufactured by Ricoh Co., Ltd.), and the landing positions of the droplets were observed with a microscope (VHX-7000, manufactured by Keyence Corporation) and evaluated according to the following criteria. Note that a grade of B or higher is considered to be at a practical level.
[Evaluation criteria]
A: No missing dots or bent dots were observed. B: A few dots were confirmed to have deviated landing positions due to bent ejection. C: Missing dots due to non-ejection were observed, or many bent dots were confirmed. D: Many missing dots due to non-ejection were confirmed.

The mixture was mixed and stirred for 30 minutes using a magnetic stirrer, and the state of the liquid composition was visually observed immediately after stirring was stopped. The results are shown in Figures 4 to 7. Figure 4 shows the state of the liquid composition with a discharge stability evaluation of A, Figure 5 shows the state of the liquid composition with a discharge stability evaluation of B, Figure 6 shows the state of the liquid composition with a discharge stability evaluation of C, and Figure 7 shows the state of the liquid composition with a discharge stability evaluation of D.
As shown in Figures 4 to 7, when the evaluation of ejection stability is good (B or higher), the contents of the composition liquid remain stable without precipitating, whereas when the evaluation of ejection stability is poor (C or lower), the contents of the composition liquid precipitate, and it is visually apparent that the contents in the composition liquid are not present stably.

The results in Tables 3 and 4 show that Examples 1 to 11 have superior properties compared to Comparative Examples 1 to 6.

REFERENCE SIGNS LIST 100 Liquid application device 110 Composition liquid application section 120 Ink application section 130 Post-treatment liquid application section 140 Drying section 150 Conveying section 160 Control means 161 Composition liquid application control section 162 Ink application control section 163 Drying control section 170 Storage section

Patent No. 5828784

Claims (8)

The composition contains water, a polyvalent metal salt, a compound represented by the following general formula (I), and a compound represented by the following general formula (II),
A liquid composition characterized in that the content of the polyvalent metal salt is 15 mass % or more.
In the general formula (I), m represents an integer of 0 or more and 6 or less, and n represents an integer of 2 or more and 19 or less.
In the general formula (II), m represents an integer of 0 or more and 4 or less, and n represents an integer of 3 or more and 15 or less. The liquid composition according to claim 1, wherein the mass ratio of the compound represented by general formula (I) to the compound represented by general formula (II) is 1:2 to 1:4. The liquid composition according to any one of claims 1 and 2, wherein the content of the polyvalent metal salt is 20% by mass or more. The composition according to any one of claims 1 to 3, wherein the polyvalent metal salt is at least one of magnesium acetate, calcium nitrate, and aluminum lactate. an ink containing a pigment and a resin;
An ink and liquid composition set comprising the liquid composition according to any one of claims 1 to 4. The ink and liquid composition set described in claim 5, wherein the pigment and the resin have an anionic charge. An image forming method comprising a liquid composition application step of applying the liquid composition described in any one of claims 1 to 4 to an absorbent recording medium. 8. The image forming method according to claim 7, further comprising an ink applying step of applying an ink containing a pigment and a resin to the absorbent recording medium to which the liquid composition has been applied.