JP7139759B2 - Image forming set, image forming apparatus and image forming method - Google Patents

Description

The present invention relates to an image forming set, an image forming apparatus and an image forming method.

The inkjet recording method is a method of recording characters and images by ejecting small ink droplets from fine nozzles and depositing them on a recording medium such as paper. Therefore, it is widely used as a home printer.

In recent years, the inkjet recording method has been expanding as a commercial printing method because of its advantages such as variable printing and compatibility with a wide range of media. In commercial printing, printing is performed on a wide variety of papers, which are broadly classified into plain paper and coated paper. However, securing the optical density (OD) of plain paper and securing the glossiness of coated paper require different ink functions. Therefore, in image formation, color reproducibility of images, abrasion resistance, durability, light resistance, drying properties of images, bleeding of characters (feathering), bleeding of color borders (color bleeding), beading, double-sided printing properties, ejection It is very difficult to satisfy all the required properties such as stability, and the inks to be used are selected according to the characteristics prioritized according to the application.

Therefore, it is possible to increase the image density and chroma even on plain paper and coated paper by previously applying a treatment liquid having a function of aggregating the coloring material onto the recording medium and jetting the ink onto that portion for printing. An inkjet recording method capable of
For example, in Patent Document 1 below, for the purpose of preventing the occurrence of cockling of a recording material, etc., a treatment liquid having a specific viscosity is applied to a coated paper by the Bristow method. An ink jet recording method is disclosed in which ink is ejected onto the coated paper after application by a roll coating method based on the index of the amount of transfer Vi at the inflection point where the value of the coefficient changes.

However, in the method disclosed in Patent Document 1, the treatment liquid does not spread evenly on the roller and the coated paper, and the coagulant contained in the treatment liquid is unevenly present on the coated paper, resulting in poor image quality. Also, there is a problem that unevenness is visible.

In addition to the technique disclosed in Japanese Patent Application Laid-Open No. 2002-200001, a recording medium having a surface coated with a white pigment or a water-soluble polymer has been proposed. However, this proposal is expensive because it requires special processing on the recording medium, and is limited to special applications such as photographic image output, and has not yet spread widely.

On the other hand, according to the studies of the present inventors, it has been found that when the treatment liquid and the ink permeate into the inside of the recording medium, color development deteriorates and beading occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming set capable of suppressing the occurrence of beading and preventing the occurrence of curling.

The above problem is solved by the following configuration 1).
1) An image forming set comprising a recording medium and a treatment liquid applied to the recording medium, wherein the treatment liquid contains a polyvalent metal salt and a surfactant and has a dynamic surface tension of 15 ms. The relationship between (A) and static surface tension (B) satisfies the relationships 59 ≥ A ≥ 50 mN / m, 27 ≤ B ≤ 38 mN / m, 2.1 ≥ A / B ≥ 1.5, and the recording The medium and the treatment liquid satisfy the relationship of 1.5≦(Vi/Vr)≦2.5 as the relationship between the roughness index Vr obtained by the Bristow method and the liquid absorption amount Vi at 20 ms ^0.5 . wherein the surfactant contained in is 0.0001% by mass or more and 0.0010% by mass or less .

According to the present invention, it is possible to provide an image forming set capable of suppressing the occurrence of beading and preventing the occurrence of curling.

FIG. 1 is a perspective explanatory view showing an example of an inkjet recording apparatus. FIG. 2 is a perspective explanatory view showing an example of a main tank in the inkjet recording apparatus.

As a result of extensive studies, the inventors of the present invention have found that the degree of permeation of the treatment liquid into the recording medium greatly affects beading, curling, and cockling of the recording medium. It is effective to set the type of coagulant in the treatment liquid, the relationship between the dynamic surface tension and the static surface tension of the treatment liquid, the roughness of the recording medium, and the amount of the treatment liquid absorbed by the recording medium within specific ranges. I found that

Based on the above findings, the image forming set of the present invention must have a recording medium and a treatment liquid to be applied to the recording medium, and satisfy all of the following conditions (1) to (3).
(1) The treatment liquid contains a polyvalent metal salt.
(2) The treatment liquid has a relationship between dynamic surface tension (A) and static surface tension (B) at 15 ms, 59≧A≧50 mN/m, 27≦B≦38 mN/m, and 2.1≧A/m. It satisfies the relationship B≧1.5.
(3) The recording medium and the treatment liquid satisfy the relationship of 1.5≦(Vi/Vr)≦2.5 as the relationship between the roughness index Vr obtained by the Bristow method and the liquid absorption amount Vi at 20 ms ^0.5 .

The image forming set of the present invention satisfies all of the above conditions (1) to (3), thereby ensuring a sufficient amount of the treatment liquid immediately after being applied onto the surface of the recording medium, and increasing the amount of the treatment liquid over time. can suppress the penetration of the ink, increase the cohesiveness of the coloring material of the ink with a small amount of application, and suppress the occurrence of beading. In addition, since the aggregation of the coloring material of the ink is completed before the treatment liquid permeates the recording medium, curling and cockling of the recording medium can be suppressed.

The treatment liquid used in the present invention contains a polyvalent metal salt as a flocculating agent. The treatment liquid preferably contains an organic solvent and water, and may contain a surfactant, an antifoaming agent, a pH adjuster, an antiseptic antifungal agent, an antirust agent, and the like, if necessary. Organic solvents, surfactants, antifoaming agents, pH adjusters, antiseptic antifungal agents, and anticorrosive agents can be the same materials as those used in the ink described below, and are also used in known treatment liquids. material can be used.

In particular, when the treatment liquid contains a water-soluble organic solvent, the effects of suppressing evaporation of water and deposition of metal salts are exhibited. In this embodiment, the content of the water-soluble organic solvent contained in the treatment liquid is preferably 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 40% by mass or less.

Moreover, when the treatment liquid contains a surfactant, it is possible to uniformly apply the treatment liquid onto the recording medium. In this embodiment, the content of the surfactant contained in the treatment liquid is preferably 5% by mass or less at which the surfactant does not separate.

The polyvalent metal salt can be composed of specific polyvalent metal ions having a valence of 2 or more and anions that bind to these polyvalent metal ions. Salts include calcium salts, magnesium salts, nickel salts, aluminum salts, boron salts, zinc salts and the like, preferably calcium salts and magnesium salts, more preferably magnesium salts. The polyvalent metal salt contained in the treatment liquid does not have to be of one type, and may be composed of two or more types.
Specific examples of polyvalent metal salts include the following inorganic metal salts and organic acid metal salts.

Examples of inorganic metal salts include calcium chloride, magnesium chloride, calcium bromide, magnesium bromide, calcium nitrate, magnesium nitrate, magnesium sulfate and the like.
Examples of organic acid metal salts include calcium salts and magnesium salts of pantothenic acid, propionic acid, ascorbic acid, acetic acid, and lactic acid.

The content of the polyvalent metal salt in the treatment liquid is, for example, 10 to 40% by mass, preferably 15 to 30% by mass.

In the treatment liquid of the present invention, the relationship between dynamic surface tension (A) and static surface tension (B) at 15 ms is 59≧A≧50 mN/m, 27≦B≦38 mN/m, and 2.1≧A/B. It satisfies the relationship ≧1.5. By setting the dynamic surface tension (A) at 15 ms to 50 mN/m or more, it is possible to suppress the permeation of the treatment liquid into the recording medium. allows for even application.
In addition, by setting the static surface tension (B) to 27 mN/m or more, it is possible to uniformly leave the coagulant component on the recording medium, and by setting it to 38 mN/m or less, it is possible to spread the treatment liquid on the recording medium. spreads evenly and can be applied.

15 ms dynamic surface tension (A) is a value measured by the maximum bubble pressure method at a temperature of 25 ° C. and a bubble lifetime of 15 ms, for example, measured using a dynamic surface tension meter SITA DynoTester (manufactured by Eiko Seiki Co., Ltd.). can do.
Also, the static surface tension (B) can be measured at a temperature of 25° C. using a surface tensiometer DY300 (manufactured by Kyowa Interface Co., Ltd.).

Although the method for adjusting the dynamic surface tension (A) in the treatment liquid is not particularly limited, it can be controlled to a desired value, for example, by appropriately changing the type and amount of surfactant added to the treatment liquid.
In addition, the method for adjusting the static surface tension (B) in the treatment liquid is not particularly limited. can be controlled to

Further, the recording medium and the processing liquid in the present invention must satisfy the relationship of 1.5≦(Vi/Vr)≦2.5 as the relationship between the roughness index Vr obtained by the Bristow method and the liquid absorption amount Vi at 20 ms ^0.5 . be. By setting (Vi/Vr) to 1.5 or more, it becomes possible to suppress the absorption of the treatment liquid regardless of the type of the recording medium and leave the aggregation component on the recording medium. , it is possible to suppress the intrusion of excess processing liquid into the inside of the recording medium, thereby preventing curling and cockling.

Bristow method is JAPAN TAPPI paper pulp test method No. 51-87, "Test Method for Liquid Absorbency of Paper and Paperboard", and is known. Both the roughness index and the amount of liquid absorption by the Bristow method are measured using the recording medium to be printed and the processing liquid to be used.

From the viewpoint of improving the effect of the present invention, the relationship between the roughness index Vr obtained by the Bristow method and the liquid absorption amount Vi at 20 ms ^0.5 is preferably 1.8 ≤ (Vi / Vr) ≤ 2.5, and 1.9 ≤ ( More preferably, Vi/Vr)≦2.2.

In order to adjust the relationship between the roughness index Vr and the liquid absorption amount Vi within the range described above, there is a method of adjusting the amounts of the water-soluble organic solvent and surfactant used.
The amount of the pretreatment liquid applied to the recording medium is, for example, 10 mg to 80 mg/A4, preferably 20 mg to 60 mg/A4.

The imaging set of the present invention can comprise ink. The inks used in the present invention are described below.

<Ink>
Organic solvents, water, coloring materials, resins, additives, and the like used in the ink are described below.

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

Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably 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 alkyls 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. Ethers; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, and the like.

A polyol compound having 8 or more carbon atoms and a glycol ether compound can improve ink permeability when paper is used as a recording medium.

The content of the organic solvent in the ink is not particularly limited and can be appropriately selected according to the purpose. 20% by mass or more and 60% by mass or less is more preferable.

<Water>
The content of water in the ink is not particularly limited and can be appropriately selected according to the purpose. % to 60% by mass is more preferred.

<Color material>
The coloring material is not particularly limited, and pigments and dyes can be used.
An inorganic pigment or an organic pigment can be used as the pigment. These may be used individually by 1 type, and may use 2 or more types together. Mixed crystals may also be used.
Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy color pigments such as gold and silver, and metallic pigments.
As inorganic pigments, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, carbon black produced by known methods such as contact method, furnace method, thermal method, etc. can be used.
Organic pigments 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, quinoflurone pigments, etc.). , dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like. 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 include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black and channel black, or copper and iron (C.I. Pigment Black 11). , metals such as titanium oxide, and organic pigments such as aniline black (C.I. Pigment Black 1).
Further, for color, C.I. 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. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 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 red), 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. I. Pigment Violet 1 (rhodamine lake), 3, 5:1, 16, 19, 23, 38, C.I. 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. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.
As dyes, acid dyes, direct dyes, reactive dyes, and basic dyes can be used without particular limitation, and may be used singly or in combination of two or more.
Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9,45,249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. I. Direct Red 1, 4, 9, 80, 81, 225, 227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. and Reactive Black 3,4,35.

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

In order to disperse the pigment in the ink, a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of coating the surface of the pigment with a resin and dispersing it, a method of dispersing using a dispersant, etc.
As a method of making a self-dispersing pigment by introducing a hydrophilic functional group into a pigment, for example, a self-dispersing pigment that is dispersible in water by adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon). can be used.
As a method for dispersing the pigment by coating the surface of the pigment with a resin, a method in which the pigment is encapsulated in microcapsules and dispersible in water can be used. This can be rephrased as a resin-coated pigment. In this case, all the pigments mixed in the ink need not be coated with a resin, and uncoated pigments or partially coated pigments may be dispersed in the ink as long as the effects of the present invention are not impaired. may be
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low-molecular-weight dispersant and high-molecular-weight dispersant typified by surfactants.
As the dispersant, it is possible to use, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. depending on the pigment.
RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used as a dispersant.
A dispersing agent may be used individually by 1 type, or may use 2 or more types together.

<Pigment dispersion>
Inks can be obtained by mixing materials such as water and organic solvents with coloring materials. Ink can also be produced by mixing a pigment, water, a dispersant, and the like to form a pigment dispersion, and then mixing materials such as water and an organic solvent.
The pigment dispersion is obtained by dispersing water, a pigment, a pigment dispersant, and optionally other components, and adjusting the particle size. Dispersion should be carried out using a disperser.
The particle diameter of the pigment in the pigment dispersion is not particularly limited, but the dispersion stability of the pigment is improved, and the image quality such as ejection stability and image density is improved. 500 nm or less is preferable, and 20 nm or more and 150 nm or less is more preferable. The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected according to the purpose. % or more and 50 mass % or less is preferable, and 0.1 mass % or more and 30 mass % or less is more preferable.
The pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifugal separator, or the like, if necessary.

<Resin>
The type of resin contained in the ink is not particularly limited and can be appropriately selected according to the purpose. resins, styrene-butadiene-based resins, vinyl chloride-based resins, acrylic-styrene-based resins, acrylic-silicone-based resins, and the like.
Resin particles made of these resins may also be used. Ink can be obtained by mixing resin particles in a resin emulsion state in which water is dispersed as a dispersion medium with a material such as a coloring material or an organic solvent. As the resin particles, appropriately synthesized ones may be used, or commercially available products may be used. Moreover, these may be used individually by 1 type, or may be used in combination of 2 or more types of resin particles.

The volume average particle diameter of the resin particles is not particularly limited and can be appropriately selected according to the intended purpose. 200 nm or less is more preferable, and 10 nm or more and 100 nm or less is particularly preferable.
The volume average particle diameter can be measured, for example, using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The content of the resin is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of fixability and storage stability of the ink, the content is 1% by mass or more and 30% by mass or less based on the total amount of the ink. is preferable, and 5% by mass or more and 20% by mass or less is more preferable.

<Additive>
Surfactants, antifoaming agents, antiseptic antifungal agents, anticorrosive agents, pH adjusters, etc. may be added to the ink as necessary.

<Surfactant>
Any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used as surfactants.
The silicone-based 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 preferable. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferred because they exhibit good properties as water-based surfactants. As the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include compounds in which a polyalkylene oxide structure is introduced into the side chain of the Si portion of dimethylsiloxane.
Examples of fluorine-based surfactants include perfluoroalkylsulfonic acid compounds, perfluoroalkylcarboxylic acid compounds, perfluoroalkylphosphoric acid ester compounds, perfluoroalkylethylene oxide adducts, and perfluoroalkyl ether groups in side chains. Polyoxyalkylene ether polymer compounds are particularly preferred due to their low foaming properties. Examples of the perfluoroalkylsulfonic acid compound include perfluoroalkylsulfonic acid and perfluoroalkylsulfonate. Examples of the perfluoroalkylcarboxylic acid compounds include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. As the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain, a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in a side chain, and a perfluoroalkyl ether group in a side chain Examples thereof include salts of polyoxyalkylene ether polymers. Counter ions of salts in these _{fluorosurfactants} include Li, Na, K, _NH4 , _NH3CH2CH2OH , _{NH2 ( CH2CH2OH} ) ₂ , and _{NH ( CH2CH2OH} ). ₃ and the like.
Examples of amphoteric surfactants include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, lauryldihydroxyethylbetaine and the like.
Nonionic surfactants include, for example, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan Examples include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates.
These may be used individually by 1 type, or may use 2 or more types together.

The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the intended purpose. Examples include polydimethylsiloxane modified at both chain ends, and polyether-modified silicone-based surfactants having polyoxyethylene groups or polyoxyethylene-polyoxypropylene groups as modifying groups exhibit excellent properties as water-based surfactants. preferable.
As such a surfactant, an appropriately synthesized one may be used, or a commercially available product may be used. Commercially available products are available from, for example, BYK Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nihon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd., and the like.
The above polyether-modified silicone-based surfactant is not particularly limited and can be appropriately selected according to the purpose. Examples include those introduced into the side chain of the Si portion of siloxane.

(However, m, n, a, and b in general formula (S-1) represent integers. R and R' represent an alkyl group and an alkylene group.)
Commercially available products can be used as the above polyether-modified silicone-based surfactants. 1906EX (Japan 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 Corporation), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.) and the like.

The content of the surfactant in the ink is not particularly limited and can be appropriately selected according to the purpose. % or more and 5 mass % or less is preferable, and 0.05 mass % or more and 5 mass % or less is more preferable.

<Antifoaming agent>
The antifoaming agent is not particularly limited, and examples thereof include silicone antifoaming agents, polyether antifoaming agents, and fatty acid ester antifoaming agents. These may be used individually by 1 type, or may use 2 or more types together. Among these, silicone-based antifoaming agents are preferred because of their excellent foam breaking effect.

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

<Antirust agent>
The rust inhibitor is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

<pH adjuster>
The pH adjuster is not particularly limited as long as it can adjust the pH to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and can be appropriately selected depending on the intended purpose. For example, viscosity, surface tension, pH and the like are preferably 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, more preferably 5 mPa·s or more and 25 mPa·s or less, from the viewpoint of improving the print density and character quality and obtaining good ejection properties. more preferred. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.). Measurement conditions are 25° C., standard cone rotor (1°34′×R24), sample liquid volume 1.2 mL, rotation speed 50 rpm, 3 minutes.
The surface tension of the ink is preferably 35 mN/m or less, more preferably 32 mN/m or less at 25° C., from the viewpoint 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 from 7 to 12, more preferably from 8 to 11, from the viewpoint of preventing corrosion of metal members in contact with the liquid.

<Recording medium>
The recording medium used for recording is not particularly limited, but includes plain paper, glossy paper, special paper, cloth, film, OHP sheet, general-purpose printing paper, and the like.

<Image forming method and image forming apparatus>
An image forming method of the present invention comprises a step of applying the treatment liquid onto a recording medium, and a step of applying ink to the recording medium to which the treatment liquid has been applied. It comprises means for applying a treatment liquid onto a recording medium, and means for applying ink to the recording medium to which the treatment liquid has been applied.
A known pretreatment device can be used to apply the treatment liquid of the present invention onto the recording medium. For example, as one aspect of the pretreatment device, a liquid container having a pretreatment liquid and a liquid ejection head, as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y) is added, and the pretreatment liquid is ejected by an inkjet recording method.
As another aspect of the pretreatment device, there is an aspect in which a pretreatment device using a blade coating method, a roll coating method, or a spray coating method other than the ink jet recording method, for example, is provided.
Next, a recording apparatus and a recording method for the ink (also referred to as the ink of the present invention) will be described.

<Recording device, recording method>
The ink of the present invention can be suitably used for various inkjet recording apparatuses, such as printers, facsimile machines, copiers, printer/facsimile/copier complex machines, stereolithography machines, and the like.
In the present application, a recording apparatus and a recording method refer to a device capable of ejecting ink, various processing liquids, and the like onto a recording medium, and a method of performing recording using the device. A recording medium means a medium to which ink or various processing liquids can adhere even temporarily.
This recording apparatus can include not only a head portion for ejecting ink, but also means for feeding, conveying, and discharging a recording medium, and other devices called pre-processing devices and post-processing devices. .
The recording apparatus and recording method may have heating means used in the heating process and drying means used in the drying process. The heating means and drying means include, for example, means for heating and drying the printing surface and the back surface of the recording medium. The heating means and drying means are not particularly limited, but for example, hot air heaters and infrared heaters can be used. Heating and drying can be performed before, during, or after printing.
Also, the recording apparatus and recording method are not limited to those that visualize significant images such as characters and graphics with ink. For example, it includes those that form patterns such as geometric patterns, and those that form three-dimensional images.
In addition, unless otherwise specified, the recording apparatus includes both a serial type apparatus in which the ejection head is moved and a line type apparatus in which the ejection head is not moved.
Furthermore, this recording device can be used not only as a desktop type, but also as a wide recording device that can print on A0 size recording media, and for example, can use continuous paper wound into a roll as a recording medium. A continuous feed printer is also included.
An example of a recording apparatus will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank. An image forming apparatus 400 as an example of a recording apparatus is a serial image forming apparatus. A mechanical unit 420 is provided inside the exterior 401 of the image forming apparatus 400 . Each ink container 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packed with, for example, an aluminum laminated film. It is made up of members. The ink containing portion 411 is housed, for example, in a container case 414 made of plastic. Thus, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided on the far side of the opening when the cover 401c of the apparatus main body is opened. A main tank 410 is detachably attached to the cartridge holder 404 . As a result, each ink discharge port 413 of the main tank 410 communicates with the ejection head 434 for each color via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 onto the printing medium.

In the present invention, the terms image formation, recording, printing, and printing are all synonymous.

Examples and comparative examples of the present invention are shown below, but the present invention is not limited to these. The amount (%) of each component described in the examples is based on solid content and mass unless otherwise specified.

(Preparation of treatment liquid)
Each component was mixed and stirred in proportions (by mass) shown in Tables 1 and 2 below to obtain various treatment liquids.

(Measurement of dynamic surface tension (A) and static surface tension (B) of treatment liquid)
The dynamic surface tension (A) and static surface tension (B) of the treatment liquid were measured by the method described above. Results are shown in Tables 1 and 2.

(Measurement of roughness index Vr and liquid absorption Vi)
The roughness index Vr and liquid absorption Vi of the treatment liquid were measured by the methods described above. Results are shown in Tables 1 and 2.
Before printing, the treatment liquid was applied to the recording medium using a wire bar (winding diameter: 0.02 mm) manufactured by Kobayashi Seisakusho Co., Ltd. in an amount of 40 mg/A4. Oven drying was performed.
Immediately after drying in the oven, printing was performed using the ink, and the following tests were performed.

The ink formulation is as follows.

(Preparation Example 1)
-Preparation of black pigment dispersion-
90 g of carbon black (Mitsubishi Chemical MA100) was added to 3,000 mL of a 2.5N sodium sulfate solution, stirred at a temperature of 60° C. and a speed of 300 rpm, and reacted for 10 hours for oxidation treatment. The resulting reaction solution was filtered, and the filtered carbon black was neutralized with a sodium hydroxide solution and subjected to ultrafiltration. The obtained carbon black was washed with water, dried, and dispersed in pure water so that the pigment concentration was 20%. As described above, a black pigment dispersion of Preparation Example 1 was prepared.

(Preparation Example 2)
-Preparation of yellow pigment dispersion-
As a yellow pigment, C.I. I. Pigment Yellow 128 was subjected to low-temperature plasma treatment to prepare a yellow pigment in which a carboxylic acid group was introduced. This was dispersed in ion-exchanged water and desalted and concentrated by an ultrafiltration membrane to obtain a yellow pigment dispersion of Preparation Example 2 having a pigment concentration of 15%.

(Preparation Example 3)
-Preparation of Magenta Pigment Dispersion-
C. I. Pigment Yellow 128 instead of C.I. I. A surface-modified magenta pigment was prepared in the same manner as in Preparation Example 2, except that Pigment Red 122 was used. This was dispersed in ion-exchanged water and desalted and concentrated by an ultrafiltration membrane to obtain a magenta pigment dispersion of Preparation Example 3 having a pigment concentration of 15%.

(Preparation Example 4)
-Preparation of cyan pigment dispersion-
C. I. Pigment Yellow 128 instead of C.I. I. A surface-modified cyan pigment was prepared in the same manner as in Preparation Example 2, except that Pigment Cyan 15:3 was used. This was dispersed in ion-exchanged water and desalted and concentrated by an ultrafiltration membrane to obtain a cyan pigment dispersion of Preparation Example 4 having a pigment concentration of 15%.

An ink composition having the following formulation was prepared and then filtered through a membrane filter having an average pore size of 0.8 μm to prepare each ink.
[Ink composition]
- 20.00% pigment dispersion obtained in each preparation example
・ 1,3-butanediol 23.00%
・Glycerin 8.00%
・2-ethyl-1,3-hexanediol 2.00%
・ Proxel LV 0.20% (manufactured by Avecia, antifungal agent)
・ 2-amino-2-ethyl-1,3-propanediol 0.30%
・Super Flex (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin) 10.00%
・Capstone FS-30 (manufactured by Dupont) 1.00% (0.80% for black)
・Remaining amount of deionized water (total: 100%)

<Evaluation>
<Beading>
IPSIO GXe5500 manufactured by Ricoh Co., Ltd. was used as the image forming device, Lumi Art Gross130 manufactured by Stora Enso was used as the recording medium, glossy paper - beautiful mode, no color correction was selected, a solid image was printed, and density unevenness (beading) was printed. was visually determined.
[Evaluation criteria]
AA: None at all.
A: Density unevenness can be slightly observed from a distance of 15 cm.
B: Density unevenness can be slightly observed from a distance of 30 cm.
C: Density unevenness can be observed even from a distance of 1 m.
D: Density unevenness can be observed even from a distance of 1.5 m or more.

<Curl>
The treatment liquid was applied to Lumi Art Gross 130, placed on a horizontal table without drying, and after 30 seconds, the warp height of the paper at the maximum vertical distance from the table was measured.
[Evaluation criteria]
A: 0-3 mm.
B: Higher than 3 mm and 5 mm or less.
C: Higher than 5 mm and 10 mm or less.
D: Higher than 10 mm.

The beading evaluation is B or higher, and the curl evaluation is B or higher, which is at a level that poses no problem in actual use.
Results are shown in Tables 1 and 2.

In Tables 1 and 2, Himax SC-506 is a polyalkylamine-based cationic polymer manufactured by Hymo Co., Ltd., Capstone-FS3100 and Capstone-FS34 are nonionic fluorine-containing surfactants manufactured by Chemours Co., Ltd. LS-106 is a polyoxyalkylene alkyl ether manufactured by Kao Corporation, and WET-270 is a polyether-modified silicone surfactant manufactured by Shin-Etsu Chemical Co., Ltd.

From the results in Tables 1 and 2, the treatment liquid of each example contains a polyvalent metal salt, and the relationship between dynamic surface tension (A) and static surface tension (B) at 15 ms is 59≧A≧50 mN/ m, 27≦B≦38 mN/m, and 2.1≧A/B≧1.5, and the recording medium and the treatment liquid have a roughness index Vr determined by the Bristow method and a roughness index Vr of ^0.5 for 20 ms. Since the relationship of 1.5≦(Vi/Vr)≦2.5 is satisfied as the relationship of the amount of liquid absorption Vi, the occurrence of beading is suppressed and curling occurs at the same time as compared with the treatment liquid of the comparative example. shown to be preventable.

400 Image forming apparatus 401 Exterior of image forming apparatus 401c Cover of apparatus main body 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For black (K), cyan (C), magenta (M), and yellow (Y) main tank 411 ink storage unit 413 ink discharge port 414 storage container case 420 mechanism unit 434 ejection head 436 supply tube

Japanese Patent No. 5513031

Claims (7)

An image forming set comprising a recording medium and a treatment liquid to be applied to the recording medium, wherein the treatment liquid contains a polyvalent metal salt and a surfactant and has a dynamic surface tension (A ) and the static surface tension (B) satisfy the following relationships: 59≧A≧50 mN/m, 27≦B≦38 mN/m, and 2.1≧A/B≧1.5, and the recording medium and The treatment liquid satisfies the relationship of 1.5≦(Vi/Vr)≦2.5 as the relationship between the roughness index Vr obtained by the Bristow method and the liquid absorption amount Vi at 20 ms ^0.5 ,
An image forming set , wherein the surfactant contained in the treatment liquid is 0.0001% by mass or more and 0.0010% by mass or less . 2. The image forming set according to claim 1, wherein the polyvalent metal salt in the treatment liquid contains either magnesium salt or calcium salt. 3. The image forming set according to claim 1, wherein the content of the polyvalent metal salt in the treatment liquid is 10% by mass or more and 40% by mass or less. 4. Any one of claims 1 to 3, wherein the treatment liquid contains a water-soluble organic solvent, and the content of the water-soluble organic solvent contained in the treatment liquid is 10% by mass or more and 50% by mass or less. The set for image formation according to claim 1. 5. The image forming set according to claim 1 , further comprising an ink containing a colorant, a water-soluble organic solvent, a resin and a surfactant. An image forming method comprising the steps of: applying a treatment liquid onto a recording medium; and applying ink to the recording medium to which the treatment liquid has been applied,
The treatment liquid contains a polyvalent metal salt and a surfactant, and the relationship between dynamic surface tension (A) and static surface tension (B) at 15 ms is 59≧A≧50 mN/m and 27≦B≦ 38 mN/m and 2.1≧A/B≧1.5, and the recording medium and the processing liquid have a roughness index Vr determined by the Bristow method and a liquid absorption Vi at 20 ms ^0.5 . satisfying the relationship 1.5 ≤ (Vi / Vr) ≤ 2.5,
An image forming method , wherein the surfactant contained in the treatment liquid is 0.0001% by mass or more and 0.0010% by mass or less . An image forming apparatus comprising means for applying a treatment liquid onto a recording medium and means for applying ink to the recording medium to which the treatment liquid has been applied,
The treatment liquid contains a polyvalent metal salt and a surfactant, and the relationship between dynamic surface tension (A) and static surface tension (B) at 15 ms is 59≧A≧50 mN/m and 27≦B≦ 38 mN/m and 2.1≧A/B≧1.5, and the recording medium and the processing liquid have a roughness index Vr determined by the Bristow method and a liquid absorption Vi at 20 ms ^0.5 . satisfying the relationship 1.5 ≤ (Vi / Vr) ≤ 2.5,
An image forming apparatus , wherein the surfactant contained in the treatment liquid is 0.0001% by mass or more and 0.0010% by mass or less .

Images