JP7515779B2 - Image forming method and image forming apparatus - Google Patents

Description

The present invention relates to an image forming method and an image forming device.

Inks using coloring materials such as pigments are known for use in applications requiring water resistance and light resistance, such as posters. When such inks are ejected by inkjet recording onto a low-absorbency recording medium, such as coated paper used in commercial printing, adjacent droplets coalesce on the recording medium, causing image defects (beading). A known method for eliminating this type of beading is to apply a treatment liquid containing a polyvalent metal salt that acts to aggregate the coloring materials in the ink to the recording medium before ejecting the ink.

For example, a treatment liquid for inkjet recording has been proposed that contains water, glycerin, and a polyvalent metal salt such as calcium nitrate or magnesium nitrate, in which the content of glycerin in the treatment liquid is 10% by mass to 50% by mass, and the content of the polyvalent metal salt in the treatment liquid is 0.8 mol/L to 2.0 mol/L (see, for example, Patent Document 1).

However, the invention of Patent Document 1 reduces the gloss of the image surface. In addition, when a liquid composition with a high glycerin content is applied to a low-absorbency recording medium such as thick paper or cardboard, and an image is formed by ejecting the ink from a head without heating the recording medium, the abrasion resistance is reduced.

The present invention aims to provide an image forming method that suppresses the occurrence of beading, suppresses the decrease in gloss caused by the treatment liquid, and achieves excellent abrasion resistance even when applying a liquid composition to a low-absorbency recording medium such as cardboard or paperboard and forming an image without heating.

As a means for solving the above problems, the image forming method of the present invention comprises the steps of:
a liquid composition applying step of applying a liquid composition to a surface of a recording medium;
an ink applying step of applying ink to the surface of the recording medium to which the liquid composition has been applied, without heating the recording medium to which the liquid composition has been applied;
The liquid composition contains a polyvalent metal salt, water, an organic solvent, and a compound represented by the following general formula (1):
The compound represented by the following general formula (1) is characterized in that m/(m+n) is 0.63 or more and 1.00 or less, and m+n is 100 or more and 270 or less.

The present invention provides an image forming method that suppresses the occurrence of beading, suppresses the loss of gloss caused by the treatment liquid, and achieves excellent abrasion resistance even when applying a liquid composition to a low-absorbency recording medium such as cardboard or paperboard and forming an image without heating.

FIG. 1 is a schematic diagram showing an example of an image forming apparatus used in the image forming method of the present invention.

(Image forming method and image forming apparatus)
The image forming method of the present invention as a means for solving the above-mentioned problems includes a liquid composition applying step of applying a liquid composition to a surface of a recording medium, and an ink applying step of applying an ink to the surface of the recording medium to which the liquid composition has been applied, without heating the recording medium to which the liquid composition has been applied, wherein the liquid composition contains a polyvalent metal salt, water, an organic solvent, and a compound represented by the following general formula (1), and the compound represented by the following general formula (1) has m/(m+n) of 0.63 or more and 1.00 or less, and m+n of 100 or more and 270 or less.

The image forming apparatus of the present invention comprises: a liquid composition applying means for applying a liquid composition to a surface of a recording medium;
an ink applying means for applying ink to the surface of the recording medium to which the liquid composition has been applied, without heating the recording medium to which the liquid composition has been applied;
The image forming apparatus is characterized in that the liquid composition contains a polyvalent metal salt, water, an organic solvent, and a compound represented by the above general formula (1), and in the compound represented by the above general formula (1), m/(m+n) is 0.63 or more and 1.00 or less, and m+n is 110 or more and 270 or less.

The image forming method of the present invention can be suitably carried out by the image forming apparatus of the present invention, and the liquid composition application step can be carried out by a liquid composition application means, the ink application step can be carried out by an ink application means, and the other steps can be carried out by other means.

By using the image forming method of the present invention, it is possible to suppress a decrease in the gloss of the image surface. In addition, when a liquid composition is applied to a low-absorbency recording medium such as cardboard or paperboard, and an image is formed by ejecting ink from a head without heating the recording medium, it is possible to suppress a decrease in abrasion resistance.

<Liquid composition application step and liquid composition application means>
The liquid composition applying step is a step of applying a liquid composition onto the surface of a recording medium, and is carried out by a liquid composition applying means.
The method of applying the liquid composition to the recording medium may be either a roller coating method in which the liquid composition is applied to the recording medium by a roller, or a liquid ejection method in which the liquid composition is applied by a head. The liquid composition includes a polyvalent metal salt, water, an organic solvent, and a compound represented by the above general formula (1). The compound represented by the above general formula (1) has m/(m+n) of 0.63 or more and 1.00 or less, and m+n of 110 or more and 270 or less, so that when the liquid composition is applied to the recording medium and then the ink is applied to form a solid image, the gloss of the image surface can be suppressed from decreasing. In addition, when the liquid composition is applied to a low-absorbency recording medium such as cardboard or paperboard, and the ink is ejected from a head to form an image without heating the recording medium, the abrasion resistance can be suppressed from decreasing.
The state of the liquid composition on the recording medium before the ink is applied is preferably such that the amount of the remaining solvent in the liquid composition is 10% by mass or more.
In the present invention, the liquid composition contains a compound represented by the above general formula (1), and when the liquid composition is in a wet state, the ink is applied to improve the beading, gloss, and abrasion resistance. Although the mechanism by which such effects are obtained is not clear, it has been found that in the present invention, the liquid composition contains a compound represented by the above general formula (1), and when the liquid composition is in a wet state, the ink is applied to improve the beading, gloss, and abrasion resistance.

<Ink application step and ink application unit>
The ink application process is a process of applying ink to the surface of a recording medium without heating the recording medium to which the liquid composition has been applied, and is carried out by an ink application means. One example of the ink application process is an ink ejection process in which ink is ejected as droplets, and is carried out by an ink ejection means, which is one example of an ink application means.
The ink is ejected onto the recording medium after the liquid composition has been applied, and more preferably, the ink is applied onto the area of the recording medium onto which the liquid composition has been applied.
The method for ejecting ink onto a recording medium is preferably an ink-jet method.
As the ink, the ink used in the present invention, which will be described in detail below, can be used.

<Other steps and other means>
The other steps include, for example, a control step.
The other means may be, for example, a control means.

(Liquid Composition)
The liquid composition of the present invention contains a polyvalent metal salt, water, an organic solvent, and a compound represented by the following general formula (1), in which m/(m+n) is 0.63 or more and 1.00 or less, and m+n is 100 or more and 270 or less, and contains other components as necessary.

<Polyvinyl alcohol>
The liquid composition of the present invention contains polyvinyl alcohol represented by the above general formula (1), in which m/(m+n) is 0.63 or more and 1.00 or less, and m+n is 110 or more and 270 or less.
By using the above liquid composition, when the liquid composition is applied to a recording medium, and then ink is applied to form a solid image, it is possible to suppress the deterioration of the gloss of the image surface.In addition, when the liquid composition is applied to a low-absorbency recording medium such as cardboard or paperboard, and the ink is ejected from a head to form an image without heating the recording medium, it is possible to suppress the deterioration of abrasion resistance.

The polyvinyl alcohol represented by the above general formula (1) preferably has m/(m+n) of 0.63 or more and 0.81 or less, and more preferably has m+n of 200 or more and 270 or less.

As the polyvinyl alcohol represented by the above general formula (1), a suitably synthesized product may be used, or a commercially available product may be used. Examples of the commercially available product include JMR-3HH (manufactured by Nippon Vinyl Acetate & Poval Corporation), JMR-10HH (manufactured by Nippon Vinyl Acetate & Poval Corporation), JMR-3H (manufactured by Nippon Vinyl Acetate & Poval Corporation), JMR-10H (manufactured by Nippon Vinyl Acetate & Poval Corporation), JMR-3M (manufactured by Nippon Vinyl Acetate & Poval Corporation), JMR-8M (manufactured by Nippon Vinyl Acetate & Poval Corporation), and JMR-10M (manufactured by Nippon Vinyl Acetate & Poval Corporation). These may be used alone or in combination of two or more types. Among these, JMR-10H (manufactured by Nippon Vinyl Acetate & Poval Corporation), JMR-8M (manufactured by Nippon Vinyl Acetate & Poval Corporation), and JMR-10M (manufactured by Nippon Vinyl Acetate & Poval Corporation) are particularly preferred.

The content of polyvinyl alcohol represented by the above general formula (1) is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the liquid composition. When the content of polyvinyl alcohol represented by the above general formula (1) is 0.1% by mass or more and 10% by mass or less, the liquid composition can be applied uniformly to a recording medium without unevenness, and further, when the liquid composition is applied to a low-absorbency recording medium such as cardboard or paperboard, and the ink is ejected from a head to form an image without heating the recording medium, a decrease in abrasion resistance can be suppressed.

<Polyoxyethylene alkyl ether compound>
The liquid composition of the present invention preferably contains a polyoxyethylene alkyl ether compound represented by the following general formula (2).

（一般式（２）中、ｎは３～１１の整数である。）

(In general formula (2), n is an integer from 3 to 11.)

By using a liquid composition containing a polyoxyethylene alkyl ether compound represented by the above general formula (2), the dots of the ejected liquid composition spread more widely on the recording medium, the organic solvent in the ink evaporates and dries more easily, and the ink also has improved permeability into the recording medium. When the ink lands as droplets on the surface of the recording medium, the amount of organic solvent remaining in the ink is reduced, and the collapse of the dot shape can be suppressed.

In the polyoxyethylene alkyl ether compound represented by the above general formula (2), n is an integer of 3 to 11, preferably an integer of 6 to 9, and more preferably an integer of 6 to 8. When n is 3 to 11, when a liquid composition containing a high boiling point solvent such as glycerin is applied to a recording medium, the liquid composition spreads well on the recording medium, promoting the penetration and evaporation of the liquid composition into the recording medium, and the ink that lands after the liquid composition is applied is dried well, making the ink film stronger and improving the abrasion resistance. When n is 6 to 9, the abrasion resistance is further improved. When n is 6 or more, the storage stability of the liquid composition is improved.

As the polyoxyethylene alkyl ether compound of the above general formula (2), a compound appropriately synthesized or a commercially available product may be used. Examples of the commercially available product include TRITON HW-1000 (manufactured by Dow Chemical Co.), TERGITOL TMN-3 (manufactured by Dow Chemical Co.), TERGITOL TMN-6 (manufactured by Dow Chemical Co.), TERGITOL TMN-100X (manufactured by Dow Chemical Co.), and TERGITOL TMN-10 (manufactured by Dow Chemical Co.). These may be used alone or in combination of two or more types. Among these, TRITON HW-1000 (manufactured by Dow Chemical Co.) and TERGITOL TMN-6 (manufactured by Dow Chemical Co.) are particularly preferred.

The content of the polyoxyethylene alkyl ether compound of the above general formula (2) is preferably 0.0005% by mass or more and 1.6% by mass or less, and more preferably 0.001% by mass or more and 0.2% by mass or less, based on the total amount of the liquid composition. When the content of the polyoxyethylene alkyl ether compound of the above general formula (2) is 0.0005% by mass or more and 1.6% by mass or less, it is possible to improve abrasion resistance while suppressing the occurrence of beading.

<Polyvalent metal salt>
The liquid composition contains a polyvalent metal salt. The polyvalent metal salt associates with the colorant in the ink due to an electric charge action, forms an aggregate of the colorant, separates the colorant from the liquid phase, and promotes fixation to the recording medium. By containing a polyvalent metal salt in the liquid composition, when the liquid composition is used as a treatment liquid, the occurrence of beading can be suppressed even when a recording medium with low ink absorbency is used, and a high-quality image can be formed.

The polyvalent metal salt is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include salts of titanium compounds, chromium compounds, copper compounds, cobalt compounds, strontium compounds, barium compounds, iron compounds, aluminum compounds, calcium compounds, magnesium compounds, zinc compounds, nickel compounds, etc. These may be used alone or in combination of two or more. Among these, salts of calcium compounds, magnesium compounds, and nickel compounds are preferred, and alkaline earth metal salts such as calcium and magnesium are more preferred, from the viewpoint of effectively flocculating coloring materials such as pigments.
The polyvalent metal salt is preferably an ionic salt, and more preferably a magnesium salt or a calcium salt.

The magnesium compound is not particularly limited and can be appropriately selected depending on the purpose. Examples of the magnesium compound include magnesium chloride, magnesium acetate, magnesium sulfate, magnesium nitrate, and magnesium silicate.
The calcium compound is not particularly limited and can be appropriately selected depending on the purpose. Examples of the calcium compound include calcium carbonate, calcium nitrate, calcium chloride, calcium acetate, calcium sulfate, and calcium silicate.
The barium compound is not particularly limited and can be appropriately selected depending on the purpose. For example, barium sulfate is included.
The zinc compound is not particularly limited and can be appropriately selected depending on the purpose. Examples of the zinc compound include zinc sulfide and zinc carbonate.
The aluminum compound is not particularly limited and can be appropriately selected depending on the purpose. Examples of the aluminum compound include aluminum silicate and aluminum hydroxide.
Among these, magnesium nitrate, calcium nitrate, magnesium sulfate, etc. are preferred in terms of solubility in a solvent. When a liquid composition containing these polyvalent metal salts is used as a treatment liquid, the aggregation function of the polyvalent metal salt with respect to the coloring material in the ink is improved, and beading is suppressed.

The content of the polyvalent metal salt is preferably 0.8 mol/kg or more and 1.4 mol/kg or less based on the total amount of the liquid composition. By having a polyvalent metal salt content of 0.8 mol/kg or more, the occurrence of beading can be suppressed even when a recording medium with low ink absorbency is used, and a high-quality image can be formed. Furthermore, by having a polyvalent metal salt content of 1.4 mol/kg or less, the storage stability of the liquid composition is improved.

In addition, when the liquid composition contains glycerin, which is a high boiling point solvent, the mass ratio of the content of glycerin in the liquid composition to the content of the polyvalent metal salt in the liquid composition is preferably 1.05 or more, and more preferably 1.2 or more. When the liquid composition containing the polyvalent metal salt is used as a treatment liquid, the mass ratio of 1.05 or more suppresses the precipitation of crystals of the polyvalent metal salt, and abnormal images (uneven image density) caused by the precipitation of crystals can be suppressed.

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

The content of the organic solvent 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, based on the total amount of the liquid composition, from the viewpoint of drying property.

<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 is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of drying property, the water content is preferably from 10% by mass to 90% by mass, and more preferably from 20% by mass to 60% by mass, based on the total amount of the liquid composition.

The liquid composition may contain a surfactant. The surfactant reduces the surface tension of the liquid composition, and when the liquid composition is used as a treatment liquid, it has the effect of improving the wettability of various recording media, allowing the treatment liquid to be applied evenly. The surfactant can increase the penetration speed of the treatment liquid into various recording media by making it appropriately easy for the treatment liquid to wet the recording media. By increasing the penetration speed of the treatment liquid, excessive aggregation of coloring materials contained in the ink applied to the recording medium to which the treatment liquid has been applied can be suppressed.

<Surfactant>
As the surfactant, any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used.
Silicone surfactant is not particularly limited and can be appropriately selected according to purpose, but it is preferable that it does not decompose even at high pH. Examples of silicone surfactants include side chain modified polydimethylsiloxane, both end modified polydimethylsiloxane, one end modified polydimethylsiloxane, side chain both end modified polydimethylsiloxane, etc. Those having polyoxyethylene group or polyoxyethylene polyoxypropylene group as modified group are particularly preferable because they show good properties as aqueous surfactants. In addition, polyether modified silicone surfactants can also be used as silicone surfactants, and examples thereof include compounds in which polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane.
As the fluorine surfactant, for example, perfluoroalkyl sulfonic acid compound, perfluoroalkyl carboxylic acid compound, perfluoroalkyl phosphate compound, perfluoroalkyl ethylene oxide adduct and polyoxyalkylene ether polymer compound having perfluoroalkyl ether group in the side chain are particularly preferred because they have low foaming properties.As the perfluoroalkyl sulfonic acid compound, for example, perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, etc. can be mentioned.As the perfluoroalkyl carboxylic acid compound, for example, perfluoroalkyl carboxylic acid, perfluoroalkyl carboxylate, etc. can be mentioned.As the polyoxyalkylene ether polymer compound having perfluoroalkyl ether group in the side chain, for example, sulfate ester salt of polyoxyalkylene ether polymer having perfluoroalkyl ether group in the side chain, salt of polyoxyalkylene ether polymer having perfluoroalkyl ether group in the side chain, etc. can be mentioned. Counter ions _of the salts in these fluorosurfactants 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 the anionic surfactant include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, and polyoxyethylene alkyl ether sulfates.
These may be used alone or in combination of two or more.

The silicone surfactant is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, side-chain both-end modified polydimethylsiloxane, etc. Among these, polyether-modified silicone surfactants having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferred because they exhibit good properties as an aqueous surfactant.
Such surfactants may be appropriately synthesized or commercially available products, such as those available from BYK-Chemie Co., Ltd., 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. For example, it can be one in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylpolysiloxane, as represented by the following general formula (S-1).
(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, for example, KF-618, KF-642, KF-643 (manufactured by Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX (manufactured by Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (manufactured by Dow Corning Toray Silicone Co., Ltd.), BYK-33, BYK-387 (manufactured by BYK-Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (manufactured by Toshiba Silicon Co., Ltd.), and the like.

The fluorosurfactant is preferably a compound having 2 to 16 fluorine-substituted carbon atoms, and more preferably a compound having 4 to 16 fluorine-substituted carbon atoms.
Examples of fluorosurfactants include perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chains, etc. Among these, polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chains are preferred because they have low foaming properties, and fluorosurfactants represented by the following general formulas (F-1) and (F-2) are more 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 above 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.
As the fluorosurfactant, commercially available products may be used. Examples of the 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 Three Industries Co., Ltd.). Megafac F-470, F-1405, F-474 (all manufactured by DIC Corporation); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chem Ours); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omnova Co., Ltd.), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), etc. Among these, FS-3100, FS-34, and FS-300 manufactured by Chemours Corporation, FT-110, FT-250, FT-251, FT-400S, FT-150, and FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omnova, and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferred.

The content of the surfactant is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.001% by mass or more and 5% by mass or less, and more preferably 0.05% by mass or more and 5% by mass or less, based on the total amount of the liquid composition.

<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.

<Anti-septic and anti-fungal agents>
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 sulfite and sodium thiosulfate.

<pH Adjuster>
There are no particular limitations on the pH adjuster, so long as it is capable of adjusting the pH to 7 or higher, and examples of the pH adjuster include amines such as diethanolamine and triethanolamine.

<Method of producing liquid composition>
The liquid composition can be obtained by dispersing or dissolving the components in an aqueous medium, and further stirring and mixing as necessary. Stirring and mixing can be performed using a stirrer with a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like.

<Physical Properties of Liquid Composition>
The physical properties of the liquid composition are not particularly limited, and the viscosity, surface tension, pH, etc. can be appropriately selected depending on the purpose.
The viscosity of the liquid composition is preferably 0.5 mPa·s or more and 30 mPa·s or less at 25° C. Here, the viscosity can be measured, for example, using a viscometer (device name: RE-550L, manufactured by Toki Sangyo Co., Ltd.).
The surface tension of the liquid composition at 25° C. is preferably 45 mN/m or less, and more preferably 40 mN/m or less.
The pH of the liquid composition is, for example, preferably 4 or more and 12 or less, and more preferably 6 or more and 10 or less.

<Uses of the liquid composition>
The liquid composition of the present invention is used as a treatment liquid for a recording medium in an image forming method.
The treatment liquid is a liquid that has the effect of aggregating the coloring material in the ink, and is applied to a recording medium, thereby, for example, aggregating the coloring material in the ink that is applied later to the recording medium to which the treatment liquid has been applied.

<Ink>
The ink used in the present invention preferably has a static surface tension of 25 mN/m or less. The organic solvent, water, coloring material, resin, additives, etc. used in the ink will be described below.

<Organic Solvent>
The organic solvent used in the ink is not particularly limited, and any water-soluble organic solvent can be used, such as 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, 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 the 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, ethylene carbonate, and the like.
It is preferable to use an organic solvent having a boiling point of 250° C. or less, since this not only functions as a wetting agent but also provides good drying properties.

The content of the organic solvent in the ink is not particularly limited and can be selected appropriately depending on the purpose, but from the viewpoint of the drying property 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>
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 is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of the drying property and ejection reliability of the ink, the water content is preferably from 10% by mass to 90% by mass, and more preferably from 20% by mass to 60% by mass, of the total amount of the ink.

<Coloring material>
The coloring material is not particularly limited, and pigments and dyes can be used.
As the pigment, an inorganic pigment or an organic pigment can be used. These pigments can be used alone or in combination of two or more. Also, mixed crystals can 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.
As organic pigments, azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye type chelates, acid dye type chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. can be used. Among these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
Specific examples of pigments for black colors 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).
Further, 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 ochre), 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, and the like.

The dye is not particularly limited, and an acid dye, a direct dye, a reactive dye, or a basic dye can be used. One type of dye may be used alone, or two or more types may be used in combination.
As dyes, for example, 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. Direct 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 and the like.

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 in which a hydrophilic functional group is introduced into the pigment to make it a self-dispersing pigment, a method in which the surface of the pigment is coated with a resin and then dispersed, and a method in which a dispersant is used to disperse the pigment.
As a method for making a pigment self-dispersible by introducing a hydrophilic functional group into the pigment, for example, a method for making the pigment dispersible in water by adding a functional group such as a sulfone group or a carboxyl group to the pigment (e.g., carbon) can be mentioned.
A method for dispersing a pigment by coating its surface with a resin includes a method for encapsulating the pigment in a microcapsule to make it dispersible in water. This can be called a resin-coated pigment. In this case, it is not necessary for all of the pigments blended in the ink to be coated with a resin, and uncoated or partially coated pigments may be dispersed in the ink as long as 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 polymeric 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 Oil 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>
It is possible to obtain ink by mixing a pigment with materials such as water or an organic solvent, or it is also possible to manufacture ink by mixing a pigment with other materials such as water and a dispersant to prepare a pigment dispersion, and then mixing the resulting mixture with materials such as water or an organic solvent.
The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. Dispersion is preferably performed using a dispersing machine.
Although there is no particular restriction on the particle size of the pigment in the pigment dispersion, the maximum frequency in terms of 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 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. From the viewpoints 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 or a centrifugal separator, and degas the pigment 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 of the resin 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 be used. The resin particles may be dispersed in water as a dispersion medium to form a resin emulsion, and the resin particles may be mixed with materials such as coloring materials and organic solvents to obtain an ink. The resin particles may be appropriately synthesized or may be 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 property 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 limitations on the resin content, and it can be selected appropriately depending on the purpose, but 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, based on the total amount of ink.

<Solid content in ink>
The particle size of the solid content in the ink is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of improving image quality such as ejection stability and image density, the maximum frequency of the particle size of the solid content in the ink is preferably 20 nm or more and 1,000 nm or less, and more preferably 20 nm or more and 150 nm or less, calculated as the maximum number of particles. The solid content includes resin particles, pigment particles, etc. The particle size can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

<Other ingredients>
The ink may contain other components such as a surfactant, an antifoaming agent, an antiseptic/antifungal agent, an antirust agent, a pH adjuster, etc., as necessary, and the other components are the same as those in the liquid composition described above.

<Ink manufacturing method>
The ink can be obtained by dispersing or dissolving the components in an aqueous medium, and further stirring and mixing as necessary. Stirring and mixing can be performed using a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like.

<Ink properties>
The physical properties of the ink are not particularly limited and can be appropriately selected depending on the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc. are within the following ranges.
The viscosity of the ink at 25°C is preferably 5 mPa·s or more and 30 mPa·s or less, and more preferably 5 mPa·s or more and 25 mPa·s or less, in terms of improving the print density and character quality and obtaining good ejection properties. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L, manufactured by Toki Sangyo Co., Ltd.). The measurement conditions are 25°C, a standard cone rotor (1°34'×R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.
The static surface tension of the ink is preferably 25 mN/m or less, and more preferably 22 mN/m or less at 25° C., in order to ensure that the ink is appropriately leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably 7 or more and 12 or less, and more preferably 8 or more and 11 or less, from the viewpoint of preventing corrosion of metal members that come into contact with the ink.

<Recording media>
The recording medium is not particularly limited and may be plain paper, glossy paper, special paper, cloth, or the like, but is particularly suitable for use with low permeability substrates (low absorbency substrates).
The low permeability substrate means a substrate having a surface with low water permeability, absorbency, or adsorption, and includes materials that have many cavities inside but are not open to the outside. Examples of low permeability substrates include recording media such as coated paper used in commercial printing and paperboard with a surface coating of recycled paper pulp blended in the middle layer and back layer. When a low permeability recording medium is used in this way, the dot shape is easily distorted in the dots formed by the ink applied to the recording medium after the treatment liquid is applied. Therefore, it is preferable to use a low absorbency recording medium in combination with the treatment liquid of the present invention, since the distorted dot shape can be suppressed.

<Low permeability substrate>
Examples of low-permeability substrates include recording media such as coated paper having a support and a surface layer provided on at least one side of the support, and further having other layers as necessary.

In a recording medium having a support and a surface layer, the amount of pure water transferred to the recording medium in a contact time of 100 ms, as measured with a dynamic scanning absorptiometer, is preferably 2 mL/ ^m2 or more and 35 mL/ ^m2 or less, and more preferably 2 mL/ ^m2 or more and 10 mL/ ^m2 or less.

If the amount of ink and pure water transferred during a contact time of 100 ms is too small, beading may occur more easily, and if it is too large, the ink dot diameter after image formation may be smaller than the desired diameter.

The amount of pure water transferred to the recording medium in a contact time of 400 ms measured by a dynamic scanning absorptiometer is preferably 3 mL/m ² or more and 40 mL/m ² or less, and more preferably 3 mL/m ² or more and 10 mL/m ² or less.

If the amount of transfer at a contact time of 400 ms is small, the drying will be insufficient, and if the amount is too large, the gloss of the image area after drying may be prone to decrease. The amount of pure water transferred to the recording medium at contact times of 100 ms and 400 ms can both be measured on the side of the recording medium that has the surface layer.

The dynamic scanning absorptometer (DSA, Journal of the Paper and Pulp Technology Association, Vol. 48, May 1994, pp. 88-92, Shigenori Kuga) is a device that can accurately measure the amount of absorbed liquid in an extremely short time. The dynamic scanning absorptometer automates the measurement by directly reading the absorption speed from the movement of the meniscus in the capillary, scanning the absorption head in a spiral over a disk-shaped sample, automatically changing the scanning speed according to a preset pattern, and measuring the required number of points on one sample.

The liquid supply head for the paper sample is connected to the capillary via a Teflon (registered trademark) tube, and the position of the meniscus in the capillary is automatically read by an optical sensor. Specifically, the amount of transferred pure water or ink can be measured using a dynamic scanning absorptiometer (K350 series D type, manufactured by Kyowa Seiko Co., Ltd.).

The transfer amounts at contact times of 100 ms and 400 ms can be calculated by interpolation from the measured values of the transfer amounts at contact times adjacent to each contact time.

<Recording medium to which liquid composition has been applied>
The recording medium is applied with the liquid composition, and in the present invention, the recording medium to which the liquid composition has been applied is referred to as a "recording medium to which the liquid composition has been applied." The recording medium to which the liquid composition has been applied is one that is not heated and is in a wet state, and may also be one to which ink has been further applied.
The recording medium to which the liquid composition has been applied contains the polyvalent metal salt, which is a component of the liquid composition, and the polyvinyl alcohol represented by the general formula (1). Note that, since the liquid composition applied to the recording medium is not heated, these components remain in the recording medium to which the liquid composition has been applied.

Here, an embodiment of an image forming apparatus will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing an example of an image forming apparatus.

The image forming device 1 shown in FIG. 1 is a device that forms an image on a recording medium 2 by applying the above-mentioned treatment liquid and ink to the recording medium 2. The image forming device 1 includes a paper feed means 3, a treatment liquid application means 4, an ink application means 5, a first heating means 6-1 and a second heating means 6-2 as heating means, and a winding means 7.

The paper feed means 3 is a means for feeding the recording medium 2 to a position where the treatment liquid application means 4 and the ink application means 5 apply the treatment liquid and ink. In the example shown in FIG. 1, continuous paper is used as the recording medium 2. Continuous paper is a recording medium that is continuous in the transport direction during image formation and is longer than the length of a print unit (one page) in the transport direction. As the continuous paper, for example, rolled rolled paper can be used. In the example shown in FIG. 1, the paper feed means 3 is a paper feed roller, and the recording medium 2 rolled up in a roll is set in the paper feed means 3.

The treatment liquid application means 4 is a means for applying a treatment liquid to the fed recording medium 2 to process the surface of the recording medium 2. The treatment liquid application means 4 is preferably a means for applying the treatment liquid by an inkjet recording method. In the case of a means for applying the treatment liquid by an inkjet recording method, it is preferable that the means has one ejection head corresponding to the treatment liquid.

The ink application means 5 is a means for applying ink to the recording medium 2 to which the treatment liquid has been applied, thereby forming an image. The ink application means 5 is preferably a means for applying ink by an inkjet recording method. In the case of a means for applying ink by an inkjet recording method, it is preferable that the ink application means has four ejection heads corresponding to black (K), cyan (C), magenta (M), and yellow (Y).

The inkjet recording method is a method in which a stimulus is applied to a liquid composition to eject the liquid composition. There are no particular limitations on the stimulus, and it can be appropriately selected depending on the purpose. Examples of the stimulus include heat (temperature), pressure, vibration, and light. One type of stimulus may be used alone, or two or more types may be used in combination. Of these, heat and pressure are preferably used.

Examples of the liquid composition ejection mode used in the liquid composition include a so-called piezo method, in which a piezoelectric element is used as a pressure generating means for pressurizing the liquid composition in the liquid composition flow path to deform a vibration plate forming the wall of the liquid composition flow path, thereby changing the internal volume of the liquid composition flow path and ejecting liquid composition droplets; a so-called thermal method, in which a heating resistor is used to heat the liquid composition in the liquid composition flow path to generate bubbles; and an electrostatic method, in which a vibration plate forming the wall of the liquid composition flow path and an electrode are arranged opposite each other, and the vibration plate is deformed by electrostatic force generated between the vibration plate and the electrode, thereby changing the internal volume of the liquid composition flow path and ejecting liquid composition droplets.

The size of the droplets of the liquid composition to be ejected is preferably, for example, 3.0 pL or more and 4.5 pL or less, the ejection speed is preferably 5 m/s or more and 20 m/s or less, the drive frequency is preferably 1 kHz or more, and the resolution is preferably 300 dpi or more.

The above-mentioned ejection heads may each be provided with a container (one example of a container means) such as a sub-tank that contains the liquid composition. The liquid composition contained in the ejection head may be supplied from another container as a main tank. Examples of the other container include a cartridge or bottle that contains the liquid composition and is casing made of resin or the like. In the cartridge, the liquid composition may be contained in an aluminum pouch with an inner bag made of resin such as polyethylene.

The image forming apparatus 1 in FIG. 1 is provided with a first heating means 6-1 and a second heating means 6-2 as heating means. The first heating means 6-1 is not particularly limited as long as it heats the surface of the recording medium 2 on which the treatment liquid has been applied, and examples thereof include a hot air device that blows hot air onto the recording medium 2, or an infrared ray irradiation device that irradiates infrared rays. The second heating means 6-2 is not particularly limited as long as it heats the opposite surface of the recording medium 2 on which the treatment liquid has been applied, and an example thereof is a heating roller. The heating roller may have a heater provided in the roller portion, or a heater that heats the roller portion may be provided outside the roller portion.

The winding means 7 is a means for winding up the recording medium 2 that has been fed by the paper feeding means 3, has had treatment liquid applied by the treatment liquid application means 4, has had ink applied by the ink application means 5, and has been heated by the heating means. When the winding means 7 winds up the recording medium 2, the recording medium 2 is transported in the transport direction indicated by the arrow A in FIG. 1. Note that, although the example shown in FIG. 1 shows a case where roll paper is used as the recording medium, the recording medium used in the present invention is not limited to this.

The recording medium may also be continuous paper that is not wound into a roll, such as continuous paper folded at predetermined intervals or continuous forms with cuttable perforations formed at predetermined intervals. In this way, when a recording medium other than roll paper is used, there is no need to wind up the recording medium, so the winding means 7 shown in Figure 1 can be omitted.

In addition, in the image forming apparatus according to this embodiment, cut paper may be used as the recording medium, not limited to continuous paper. Cut paper is an independent recording medium for each print unit (one page) in the transport direction during image formation.

In addition to the above-mentioned means, the image forming apparatus 1 may also be equipped with a post-processing device that performs post-processing using a post-processing liquid or the like on the recording medium after the image portion has been formed.

Furthermore, each of the means such as the treatment liquid application means 4, the ink application means 5, and the winding means 7 is not limited to being provided in the image forming apparatus 1 which is a single device, but for example, each of the means such as the treatment liquid application means 4, the ink application means 5, and the winding means 7 may be distributed and present in separate devices.
The image forming apparatus is not limited as long as it forms an image area on a recording medium by ejecting the above-mentioned treatment liquid, ink, and any liquid composition as necessary. Examples of the image forming apparatus include a printer, a facsimile machine, a copying machine, a printer/facsimile/copying machine combination machine, and a three-dimensional modeling apparatus.

The following describes examples of the present invention, but the present invention is not limited to these examples. Note that the following examples and comparative examples show examples in which a liquid composition is used as a treatment liquid.

(Preparation Example of Pigment Coating Resin)
-Synthesis of styrene-acrylic copolymer A-
A stirring device, a dropping device, a temperature sensor, and a reaction vessel equipped with a reflux device having a nitrogen introduction device at the top of the reaction vessel of an automatic polymerization reaction apparatus (Todoroki Sangyo Co., Ltd., polymerization tester DSL-2AS type) were charged with 550 g of methyl ethyl ketone, and the inside of the reaction vessel was replaced with nitrogen while stirring. After heating to 80 ° C. while maintaining the inside of the reaction vessel in a nitrogen atmosphere, a mixed solution of 75.0 g of 2-hydroxyethyl methacrylate, 77.0 g of methacrylic acid, 80.0 g of styrene, 150.0 g of butyl methacrylate, 98.0 g of butyl acrylate, 20.0 g of methyl methacrylate, and 40.0 g of "Perbutyl (registered trademark) O" (manufactured by NOF Corporation) was dropped over 4 hours by the dropping device. After the dropwise addition was completed, the reaction was continued for a further 15 hours at the same temperature to obtain a methyl ethyl ketone solution of an anionic group-containing styrene-acrylic copolymer A having an acid value of 100 mgKOH/g, a weight average molecular weight of 21,000 and a glass transition temperature Tg (calculated value) of 31°C.
After the reaction was completed, a portion of the methyl ethyl ketone was distilled off under reduced pressure to obtain a solution of an anionic group-containing styrene-acrylic copolymer A in which the non-volatile content was adjusted to 50% by mass.

(Preparation Example of Pigment Dispersion)
--Preparation of Pigment Dispersion 1--
Into a mixing tank equipped with a cooling jacket, 1,000 g of copper phthalocyanine (SEIKALIGHT BLUE A612, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), 800 g of the anionic group-containing styrene-acrylic copolymer A solution, 143 g of a 10% by mass aqueous sodium hydroxide solution, 100 g of methyl ethyl ketone, and 1,957 g of water were charged and mixed with stirring.
The resulting mixture was passed through a dispersing device (manufactured by Nippon Coke & Engineering Co., Ltd., SC Mill SC100) filled with zirconia beads having a diameter of 0.3 mm, and dispersed for 6 hours by a circulation method (a method in which the dispersion liquid coming out of the dispersing device is returned to the mixing tank). The rotation speed of the dispersing device was 2,700 rpm, and cold water was passed through the cooling jacket so that the temperature of the dispersion liquid was kept below 40 ° C. After the dispersion was completed, the stock dispersion liquid was extracted from the mixing tank, and then the mixing tank and the dispersing device flow path were washed with 10,000 g of water, and the diluted dispersion liquid was obtained by combining with the stock dispersion liquid. The diluted dispersion liquid was placed in a glass distillation apparatus, and the entire amount of methyl ethyl ketone and a part of the water were distilled off. After cooling to room temperature, 10% by mass hydrochloric acid was dropped while stirring to adjust the pH to 4.5, and the solid content was filtered with a Nutsche type filtration device (manufactured by Nippon Chemical Machinery Co., Ltd., pressure filter) and washed with water. The cake was placed in a container, and 200 g of a 20 mass % aqueous potassium hydroxide solution was added, followed by dispersion using a Disper (TK Homo Disper, manufactured by Primix Corporation). Water was further added to adjust the non-volatile content, thereby obtaining Pigment Dispersion 1 in which copper phthalocyanine with a non-volatile content of 20 mass % was dispersed in an aqueous medium as composite particles coated with a carboxyl group-containing styrene-acrylic copolymer neutralized in potassium hydroxide.

--Preparation of Pigment Dispersion 2--
Pigment Dispersion 2 was obtained in the same manner as in Pigment Dispersion Preparation Example 1, except that in the preparation of Pigment Dispersion 1, copper phthalocyanine was changed to carbon black (product name: Raven 1080, manufactured by Columbian Carbon Japan Co., Ltd.).

(Ink Preparation Example)
--Preparation of Ink 1--
22.0% by mass of glycerin, 11.0% by mass of 1,3-butanediol, 2.0% by mass of 1,3-octanediol, 2.0% by mass of a surfactant (product name: E1010, manufactured by Nissin Chemical Industry Co., Ltd.), and ion-exchanged water were stirred for 1 hour to uniformly mix, and 2.0% by mass of rosin-modified maleic acid resin (Harima Chemical Co., Ltd., Harimac R-100) was added and stirred for an additional hour to uniformly mix, after which the above-mentioned pigment dispersion 1 was added so that the solid content was 8.0% by mass, and stirred for an additional hour to uniformly mix. This mixture was pressure-filtered using a polyvinylidene fluoride membrane filter having an average pore size of 0.8 μm to remove coarse particles and dust, thereby obtaining ink 1.

- Preparation of Ink 2 and Ink 3 -
Inks 2 and 3 were obtained in the same manner as in the preparation of ink 1, except that the composition of the ink was changed to the composition in Table 1 below. Note that the unit of each numerical value of the composition in Table 1 is "mass %".

Next, the static surface tension of each of the resulting inks was measured as follows. The results are shown in Table 1.

<Static surface tension>
Measurements were performed using the plate method with an automatic surface tensiometer DY-300 manufactured by Kyowa Interface Science Co., Ltd., using a platinum plate (width 23.85 mm, thickness: 0.15 mm) manufactured by Kyowa Interface Science Co., Ltd., and a hot/cold water circulator 4VT manufactured by Kyowa Interface Science Co., Ltd. to adjust the temperature of each ink to 25° C., and a stage speed of 0.2 mm/s.

(Example of varnish preparation)
- Preparation of Varnish 1 -
25% by mass of polyvinyl alcohol represented by the general formula (1) (product name: JMR10H [m+n: 270, m/(m+n): 0.81], manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.) and 75% by mass of ion-exchanged water were mixed with stirring at room temperature for 2 hours to obtain varnish 1.

- Preparation of varnishes 2 to 4, 7, and 8 -
Varnishes 2 to 4, Varnish 7, and Varnish 8 were obtained in the same manner as in the preparation of Varnish 1, except that the compound represented by the general formula (1) was replaced with one shown in Table 2 below.

- Preparation of Varnish 5 -
25% by mass of polyvinyl alcohol represented by the general formula (1) (product name: JMR3HH [m+n: 100, m/(m+n): 0.985], manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.) and 75% by mass of ion-exchanged water were mixed with stirring at room temperature for 1 hour, and then heated to 90° C. and stirred for another 1 hour. The mixture was then allowed to cool to room temperature, thereby obtaining varnish 5.

- Preparation of varnishes 6 and 9 -
Varnish 6 and Varnish 9 were obtained in the same manner as in the preparation of Varnish 5, except that the compound represented by the general formula (1) was replaced with one shown in Table 2 below.

(Example of preparation of processing solution)
--Preparation of Processing Solution 1--
12% by mass of varnish 1, 0.1% by mass of a polyoxyethylene alkyl ether compound represented by the general formula (2) (trade name: TRITON HW-1000, manufactured by Dow Chemical Company), 25.6% by mass of magnesium nitrate hexahydrate (manufactured by Showa Chemical Co., Ltd.), and 29.6% by mass of glycerin were added and stirred for 1 hour to uniformly mix. Further, 32.7% by mass of ion-exchanged water was added to make the total 100% by mass, and the mixture was stirred for 1 hour to uniformly mix, thereby obtaining treatment liquid 1.

--Preparation of Processing Solutions 2 to 17--
Treatment solutions 2 to 17 were obtained in the same manner as in Treatment Solution Preparation Example 1, except that in the preparation of Treatment Solution 1, the composition of the treatment solution was changed to the composition in Tables 3-1 to 3-3 below. Note that the unit of each number for the composition in Tables 3-1 to 3-3 is "mass %".

Details of each component in Tables 3-1 to 3-3 are as follows.
-Polyoxyethylene alkyl ether compound of general formula (2)-
*TMN-3: Trade name: TERGITOL TMN-3, manufactured by Dow Chemical Company, n=3 in general formula (2)
*HW-1000: Trade name: TRITON HW-1000, manufactured by Dow Chemical Company, n=6 in general formula (2)
*TMN-6: Trade name: TERGITOL TMN-6, manufactured by Dow Chemical Company, n=8 in general formula (2)
*TMN-100X: Trade name: TERGITOL TMN-100X, manufactured by Dow Chemical Company, n=9 in general formula (2)
*TMN-10: Trade name: TERGITOL TMN-10, manufactured by Dow Chemical Company, n=11 in general formula (2)

-Surfactants-
*Unidyne DSN-403N: Polyoxyethylene perfluoroalkyl ether, manufactured by Daikin Industries, Ltd. *Unisafe A-LY: Nonionic surfactant, manufactured by NOF Corporation

- Polyvalent metal salts -
*Magnesium nitrate hexahydrate, manufactured by Showa Chemical Co., Ltd. *Calcium nitrate tetrahydrate, manufactured by Showa Chemical Co., Ltd.

<Treatment liquid and ink set>
Next, treatment liquids 1 to 17 prepared in the above treatment liquid preparation examples and inks 1 to 3 prepared in the above ink preparation examples were combined as shown in Table 4 below to form treatment liquid and ink sets of Examples 1 to 17 and Comparative Examples 1 to 5.

Next, the image quality characteristics and the liquid characteristics of the treatment liquid were evaluated using a set of treatment liquid and ink as follows. The results are shown in Table 4.

<Beading>
Using the image forming apparatus shown in Figure 1, the treatment liquid was applied to a recording medium (NEW-DV, manufactured by Hokuetsu Corporation, basis weight: 400 gsm) so that the application amount was 0.9 g/ ^m2 , and then the ink was ejected onto the recording medium to obtain a print sample. Note that a 3 cm square solid image formed with a dot pattern was used as the print chart. Next, the solid portion of the 3 cm square solid image formed with a dot pattern was visually observed, and "beading" was evaluated based on the following evaluation criteria. Note that a rating of B or higher was evaluated as being usable.
As the ink application means of the image forming apparatus, a head mounted on an image forming apparatus (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) was used.
[Evaluation criteria]
A: No beading is visible. B: Some beading is visible, but not problematic. C: Beading is visible and clearly noticeable to the naked eye.

<Gloss Difference>
Using the image forming apparatus shown in FIG. 1, the treatment liquid was applied to a recording medium (Oji Paper: OK top coat + [basis weight: 127.8 gsm]) so that the application amount was 0.9 g/ ^m2 , and then ink was ejected onto the recording medium to obtain a print sample on which the treatment liquid was applied. Next, a print sample on which the treatment liquid was not applied was obtained without applying the treatment liquid to the recording medium (Oji Paper: OK top coat + [basis weight: 127.8 gsm]). Note that a solid image of 3 cm square formed with a dot pattern was used as the print chart. Next, the 60° gloss of each of the print sample on which the treatment liquid was applied and the print sample on which the treatment liquid was not applied was measured with a gloss meter (product name: Micro-Tri-Gloss μ, manufactured by Toyo Seiki Seisakusho), and "beading" was evaluated based on the following evaluation criteria. Note that a rating of B or higher was evaluated as being practical.
As the ink application means of the image forming apparatus, a head mounted on an image forming apparatus (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) was used.
[Evaluation criteria]
A: The difference in gloss between the print sample to which the treatment liquid was applied and the print sample to which the treatment liquid was not applied was less than 2.
B: The difference in gloss between the print sample to which the treatment liquid was applied and the print sample to which the treatment liquid was not applied was less than 5.
C: The difference in gloss between the print sample to which the treatment liquid is applied and the print sample to which the treatment liquid is not applied is 5 or more.

<Abrasion resistance (nail scratches)>
Using the image forming apparatus shown in FIG. 1, the treatment liquid was applied to a recording medium (NEW-DV, manufactured by Hokuetsu Corporation, basis weight: 400 gsm) so that the application amount was 0.9 g/ ^m2 , and then the ink was ejected onto the recording medium to obtain a print sample. The print chart used was a 3 cm square solid image formed with a dot pattern. Next, the image quality after rubbing the solid portion of the 3 cm square solid image with a fingernail was visually observed, and the "abrasion resistance (nail scratch)" was evaluated based on the following evaluation criteria. A rating of B or higher was evaluated as being usable.
As the ink application means of the image forming apparatus, a head mounted on an image forming apparatus (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) was used.
[Evaluation criteria]
A: No damage was caused by scratching with a fingernail, and almost no change in image density was observed.
B: No damage occurs when scratched with a fingernail, and the image density changes. C: A small amount of damage occurs when scratched with a fingernail.
D: Scratching with a fingernail clearly caused scratches.

<Storage stability>
Each treatment liquid was placed in a 20 mL glass bottle and stored in a thermostatic chamber at 60° C. for 2 weeks. Next, using a viscometer (device name: SV-10, manufactured by A&D Co., Ltd.) at 25° C., the initial viscosity before and after 2 weeks of storage were measured, and the difference between the initial viscosity before and after 2 weeks of storage (viscosity increase level (viscosity change rate)) was calculated, and the "storage stability" was evaluated based on the following evaluation criteria. Note that cases with an evaluation of B or higher were evaluated as being usable for practical use.
[Evaluation criteria]
A: The rate of change in viscosity from the initial viscosity is less than 1%. B: The rate of change in viscosity from the initial viscosity is 1% or more but less than 5%. C: The rate of change in viscosity from the initial viscosity is 5% or more, or aggregates have occurred in the treatment liquid.

（２）前記インク付与工程において、前記記録媒体上に付与された前記液体組成物の溶媒残存量が１０質量％以上である前記録媒体表面にインクを付与する、上記（１）に記載の画像形成方法。
（３）前記一般式（１）で表される化合物は、ｍ／（ｍ＋ｎ）が０．６３以上０．８１以下であり、ｍ＋ｎが２００以上２７０以下である、上記（１）又は（２）に記載の画像形成方法。
（４）前記液体組成物が、下記一般式（２）で表されるポリオキシエチレンアルキルエーテルを含む、上記（１）乃至（３）のいずれか１項に記載の画像形成方法。

（一般式（２）中、ｎは３～１１の整数である。）
（５）前記一般式（２）で表される化合物におけるｎが６～８である、上記（４）に記載の画像形成方法。
（６）前記多価金属塩が、硝酸マグネシウム及び／又は硝酸カルシウムである、上記（１）乃至（５）のいずれか１項に記載の画像形成方法。
（７）前記インクの静的表面張力が、２５ｍＮ／ｍ以下である、上記（１）乃至（６）のいずれか１項に記載の画像形成方法。
（８）記録媒体表面に液体組成物を付与する液体組成物付与手段と、
前記液体組成物が付与された記録媒体を加熱せずに、前記液体組成物が付与された記録媒体表面にインクを付与するインク付与手段と、を含み、
前記液体組成物が、多価金属塩、水、有機溶剤、及び、下記一般式（１）で表される化合物を含み、下記一般式（１）で表される化合物は、ｍ／（ｍ＋ｎ）が０．６３以上１．００以下であり、ｍ＋ｎが１００以上２７０以下であることを特徴とする画像形成装置。

For example, aspects of the present invention are as follows.
(1) a liquid composition applying step of applying a liquid composition to a surface of a recording medium;
an ink applying step of applying ink to the surface of the recording medium to which the liquid composition has been applied, without heating the recording medium to which the liquid composition has been applied;
The liquid composition contains a polyvalent metal salt, water, an organic solvent, and a compound represented by the following general formula (1):
An image forming method, wherein the compound represented by the following formula (1) has m/(m+n) of 0.63 or more and 1.00 or less, and m+n is 100 or more and 270 or less:

(2) The image forming method according to (1) above, wherein in the ink application step, the ink is applied to a surface of the recording medium in which the remaining solvent amount of the liquid composition applied to the recording medium is 10 mass % or more.
(3) The image forming method according to (1) or (2), wherein the compound represented by the general formula (1) has m/(m+n) of 0.63 or more and 0.81 or less, and m+n of 200 or more and 270 or less.
(4) The image forming method according to any one of (1) to (3) above, wherein the liquid composition contains a polyoxyethylene alkyl ether represented by the following general formula (2):

(In general formula (2), n is an integer from 3 to 11.)
(5) The image forming method according to the above (4), wherein n in the compound represented by formula (2) is 6 to 8.
(6) The image forming method according to any one of (1) to (5) above, wherein the polyvalent metal salt is magnesium nitrate and/or calcium nitrate.
(7) The image forming method according to any one of (1) to (6) above, wherein the static surface tension of the ink is 25 mN/m or less.
(8) a liquid composition applying means for applying a liquid composition to a surface of a recording medium;
an ink applying means for applying ink to the surface of the recording medium to which the liquid composition has been applied, without heating the recording medium to which the liquid composition has been applied;
the liquid composition comprises a polyvalent metal salt, water, an organic solvent, and a compound represented by the following general formula (1), wherein m/(m+n) is 0.63 or more and 1.00 or less, and m+n is 100 or more and 270 or less:

The image forming methods described in (1) to (7) and the image forming apparatus described in (8) can solve the problems of the prior art and achieve the object of the present invention.

REFERENCE SIGNS LIST 1 Image forming apparatus 2 Recording medium 3 Paper supply means 4 Treatment liquid applying means 5 Ink applying means 6-1 First heating means 6-2 Second heating means 7 Winding means

Patent No. 5346751

Claims (9)

a liquid composition applying step of applying a liquid composition to a surface of a recording medium;
an ink applying step of applying ink to the surface of the recording medium to which the liquid composition has been applied, without heating the recording medium to which the liquid composition has been applied;
The liquid composition contains a polyvalent metal salt, water, an organic solvent, and a compound represented by the following general formula (1):
The compound represented by the following general formula (1) has m/(m+n) of 0.63 or more and 1.00 or less, and m+n of 100 or more and 270 or less,
The image forming method according to the present invention is characterized in that the liquid composition contains a polyoxyethylene alkyl ether represented by the following general formula (2):

(In general formula (2), n is an integer from 3 to 11.) The image forming method according to claim 1, wherein the content of the compound represented by the general formula (1) is 0.1% by mass or more and 3% by mass or less with respect to the total amount of the liquid composition. The image forming method according to claim 1 or 2, wherein the content of the polyoxyethylene alkyl ether represented by the general formula (2) is 0.0005% by mass or more and 0.2% by mass or less with respect to the total amount of the liquid composition. 4. The image forming method according to claim 1, wherein in the ink applying step, the ink is applied to a surface of the recording medium in which a remaining amount of the solvent in the liquid composition applied onto the recording medium is 10% by mass or more. The image forming method according to any one of claims 1 to 4, wherein the compound represented by the general formula (1) has m/(m+n) of 0.63 or more and 0.81 or less, and m+n of 200 or more and 270 or less. The image forming method according to any one of claims 1 to 5, wherein n in the compound represented by the general formula (2) is 6 to 8. The image forming method according to any one of claims 1 to 6, wherein the polyvalent metal salt is magnesium nitrate and/or calcium nitrate. The image forming method according to any one of claims 1 to 7, wherein the static surface tension of the ink is 25 mN/m or less. A liquid composition applying means for applying a liquid composition onto a surface of a recording medium;
an ink applying means for applying ink to the surface of the recording medium to which the liquid composition has been applied, without heating the recording medium to which the liquid composition has been applied;
the liquid composition comprises a polyvalent metal salt, water, an organic solvent, and a compound represented by the following general formula (1), wherein m/(m+n) is 0.63 or more and 1.00 or less, and m+n is 100 or more and 270 or less,
The image forming apparatus is characterized in that the liquid composition contains a polyoxyethylene alkyl ether represented by the following general formula (2):

(In general formula (2), n is an integer from 3 to 11.)

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