JP7110959B2 - SETTING OF TREATMENT LIQUID AND INK, IMAGE FORMING METHOD AND IMAGE FORMING APPARATUS - Google Patents

Description

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

The inkjet recording method is a method of recording characters and images by ejecting a small amount of ink droplets from fine nozzles and depositing them on a recording medium such as paper. Widely used as home printers.

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 paper, and the paper can be roughly divided into plain paper and coated paper. In reserve, the function of the ink required is different. For this reason, image color reproducibility, abrasion resistance, durability, light resistance, image drying, character bleeding (feathering), color boundary bleeding (color bleeding), beading, double-sided printing performance, ejection stability, etc. It is very difficult to satisfy all the required properties, and the inks to be used are selected in consideration of the features that are prioritized according to the application.

Conventionally, a recording medium coated with a material for fixing the colorant in the ink when an image is formed on the surface of the recording medium, or a recording medium coated with a white pigment or a water-soluble polymer on the surface. is proposed.
However, since it is expensive because it requires special processing, it is limited to special uses such as photographic image output, and has not spread widely.

Therefore, in order to be compatible with general recording media, a treatment liquid having cohesiveness of coloring material is sprayed or applied in advance onto the recording medium, and ink is jetted to that portion to print, so that it can be printed on plain paper or the like. An inkjet recording method has been proposed that can increase the image density and chroma even on coated printing paper.

The type, amount, and physical properties of the coagulant contained in the treatment liquid must be selected according to the polarity and dispersion method of the coloring material in the ink. For example, when a colorant pigment is dispersed in an anionic water-soluble resin, cationic polymers, cationic fine particles, organic acids, and polyvalent metal salts exhibit cohesion.
However, if the agglomeration reaction occurs too quickly, the ink droplets agglomerate before they penetrate the surface of the recording medium and spread. ) can be effectively suppressed, the density and saturation of the image may rather be lowered. Conversely, if the aggregation reaction is too slow, in the case of a recording medium without a surface coat layer such as plain paper, the ink may permeate into the interior, resulting in poor color development or beading.

In addition, if the reactivity of the coagulant contained in the treatment liquid is made too strong, the application member such as a roller for applying the treatment liquid may be deteriorated or rusted. or the method of extremely lowering the pH is not preferable.

Various methods have been proposed for this purpose. For example, in order to suppress color bleeding and feathering, Patent Document 1 discloses that a receiving solution containing a specific metal salt and a resin having one or more hydrophilic groups and/or a specific resin emulsion is adhered, and the adherence is performed. Part discloses a method of printing using an ink-jet ink comprising a water-based solvent having a phosphorus-containing group in one of a pigment and an anionic resin emulsion.

Although Patent Document 1 considers suppression of color bleeding and feathering, it does not take into account blocking caused by winding after printing or stacking of printed matter, which is a problem in a high-speed continuous feeder. Clearly, blocking occurs from configuration. In addition, no study has been made on fixability.

In view of the above, the present invention provides a set of a treatment liquid and ink that can suppress the occurrence of color bleeding, have good fixability, and suppress the occurrence of blocking due to winding and stacking after image formation. intended to provide

In order to solve the above problems, a treatment liquid and ink set of the present invention includes a treatment liquid to be applied to a recording medium, and an ink to be applied to the recording medium to which the treatment liquid has been applied. contains a polyvalent metal salt, the ink contains a urethane resin, a styrene acrylic resin and a pigment, and the static surface tension (B) of the ink and the static surface tension (C) of the treatment liquid are
0.5≦(B)/(C)≦0.7
and the 15 ms dynamic surface tension (D) of the treatment liquid and the 1500 ms dynamic surface tension (E) of the treatment liquid are:
0.5≦(E)/(D)≦0.9
35 [mN/m] ≤ (E) ≤ 55 [mN/m]
is characterized by satisfying

ADVANTAGE OF THE INVENTION According to the present invention, there is provided a set of a treatment liquid and an ink that can suppress the occurrence of color bleeding, have good fixability, and can suppress the occurrence of blocking due to winding and stacking after image formation. be able to.

1 is a perspective explanatory view of an example of an image forming apparatus according to the present invention; FIG. It is a perspective explanatory view of a main tank. FIG. 3 is a schematic diagram of another example of the image forming apparatus according to the present invention; It is an example of a print pattern for evaluating color bleeding.

Hereinafter, a set of treatment liquid and ink, an image forming method, and an image forming apparatus according to the present invention will be described with reference to the drawings. In addition, the present invention is not limited to the embodiments shown below, and can be changed within the scope of those skilled in the art, such as other embodiments, additions, modifications, deletions, etc. is also included in the scope of the present invention as long as the functions and effects of the present invention are exhibited.

The inventors of the present invention have studied the effects on beading, color bleeding, and blocking caused by differences in resins and wettability contained in treatment liquids and inks. As a result, by making the surface tension of the ink lower than the surface tension of the treatment liquid, regardless of whether or not the treatment liquid is dried, it spreads on the paper while maintaining the aggregation effect, resulting in high image density and color. It was found that the beading and color bleeding were improved. In addition, it was found to be effective in suppressing blocking while improving fixability.

According to the present invention, it is possible to suppress the occurrence of color bleeding, provide good fixability, and suppress the occurrence of blocking due to winding and stacking after image formation. In addition, the present invention is particularly effective for low-absorption recording media such as offset coated paper and impermeable recording media. Moreover, according to the present invention, excellent effects such as suppression of beading and improvement of storage stability can be obtained.

(Set treatment liquid and ink)
The treatment liquid and ink set of the present invention includes a treatment liquid to be applied to a recording medium and an ink to be applied to the recording medium to which the treatment liquid has been applied, the treatment liquid containing a polyvalent metal salt, The ink contains a urethane resin, a styrene acrylic resin, and a pigment, and the static surface tension (B) of the ink and the static surface tension (C) of the treatment liquid are
0.5≦(B)/(C)≦0.7
and the 15 ms dynamic surface tension (D) of the treatment liquid and the 1500 ms dynamic surface tension (E) of the treatment liquid are:
0.5≦(E)/(D)≦0.9
35 [mN/m] ≤ (E) ≤ 55 [mN/m]
is characterized by satisfying
Details will be described below.
A set of treatment liquid and ink may be simply referred to as an “ink set”.

<Surface tension>
In the ink set of the present invention, the static surface tension (B) of the ink and the static surface tension (C) of the treatment liquid are
0.5≦(B)/(C)≦0.7
By satisfying the condition, when the ink is applied to the recording medium to which the treatment liquid has been applied, the ink can be uniformly wetted and spread, and the image quality can be further improved.
In addition, since the static surface tension (B) of the ink is lower than the static surface tension (C) of the treatment liquid, regardless of whether or not the treatment liquid is dried, the effect of aggregating the treatment liquid is maintained while maintaining the effect on the recording medium. It can be spread wet. As a result, the occurrence of beading and color bleeding can be suppressed by the balance of wetting and spreading of the ink itself.

When (B)/(C) is less than 0.5, the first coating liquid spreads quickly, but the ink spreads poorly, resulting in deterioration of image quality such as white spots, resulting in (B)/(C). is more than 0.7, the pre-coating liquid does not wet and spread, and the ink spreads quickly, resulting in a difference in cohesion and a tendency to cause density unevenness.

In order for the static surface tension (B) of the ink and the static surface tension (C) of the treatment liquid to satisfy the above relationship, for example, the components contained in the ink and the treatment liquid and their contents are controlled.

The static surface tension (B) of the ink is preferably 35 mN/m or less, more preferably 32 mN/m or less at 25° C., because the ink is suitably leveled on the recording medium and the drying time of the ink is shortened. more preferred.

Also, the 15 ms dynamic surface tension (D) of the treatment liquid and the 1500 ms dynamic surface tension (E) of the treatment liquid are
0.5≦(E)/(D)≦0.9
35 [mN/m] ≤ (E) ≤ 55 [mN/m]
By satisfying the above, the treatment liquid can be uniformly applied to the recording medium. The method of applying the treatment liquid can be changed as appropriate, but by satisfying the above relationship, the treatment liquid can be applied uniformly and evenly even when applied by roller coating.

When (E)/(D) is less than 0.5, the penetration into the paper surface deteriorates and uneven coating occurs, and when (E)/(D) exceeds 0.9, the penetration into the paper surface becomes It goes too far, and the desired aggregation effect cannot be obtained.
In addition, if (E) is less than 35 [mN/m], it will penetrate too much into the paper, the aggregation effect of the first coating will decrease and the image quality will deteriorate, and (E) exceeds 55 [mN/m]. As a result, the coating cannot be applied uniformly on the paper surface, resulting in uneven coating.

In order for the 15 ms dynamic surface tension (D) of the treatment liquid and the 1500 ms dynamic surface tension (E) of the treatment liquid to satisfy the above relationship, for example, the components contained in the treatment liquid and their contents are controlled.

Also, the 15 ms dynamic surface tension of the ink (A) and the static surface tension of the ink (B) are
1.5≦(A)/(B)≦2
is preferably satisfied. In this case, there is an advantage that the ink spreads quickly on the paper surface and penetrates.

As a means for satisfying the above relationship between the 15 ms dynamic surface tension (A) of the ink and the static surface tension (B) of the ink, for example, the components contained in the ink and the treatment liquid and their contents are controlled. Things are mentioned.

The dynamic surface tension of the treatment liquid and ink is measured using a portable surface tension meter (SITA DynoTester, manufactured by Eiko Seiki Co., Ltd.) under conditions of temperature: 25° C. and bubble life time: 15 msec. The static surface tension of the treatment liquid and ink is measured at a temperature of 25° C. using a surface tensiometer (DY300, manufactured by Kyowa Kaimen Co., Ltd.). The units of (A) to (E) above are [mN/m].

<Ink>
The ink of the present invention contains resin (urethane resin, styrene-acrylic resin) and pigment, and if necessary, organic solvent, water, additive, surfactant, antifoaming agent, antiseptic antifungal agent, antirust agent, pH Including other ingredients such as modifiers, etc.

<<Resin>>
The ink of the present invention contains a urethane resin and a styrene-acrylic resin, and by containing the urethane resin and the styrene-acrylic resin, it is possible to obtain high fixability and high image quality on coated paper.

-Urethane resin-
By including a urethane resin in the ink of the present embodiment, it is possible to improve scratch resistance and fixability.
The volume average particle size of the urethane resin is preferably 10 nm or more and 30 nm or less. When the thickness is 10 nm or more and 30 nm or less, the urethane resin can enter into the gaps between the styrene-acrylic resin and the pigment, and the adhesion between the pigment and the resin can be improved, and the abrasion resistance and fixability can be improved.
The molecular weight is not particularly limited and can be selected depending on the purpose.

The urethane resin is preferably contained in the ink in an amount of 1.0% by mass or more and 5.0% by mass or less. By setting the amount within the above range, fixability can be secured and image quality can be improved. In addition, by making it 1.0% by mass or more, it is possible to improve the adhesion in the ink layer and between the ink layer and the recording medium, thereby improving the abrasion resistance. By making it 5.0% by mass or less, the occurrence of blocking can be suppressed and the storage stability of the ink can be ensured.

Moreover, it is preferable that the glass transition temperature Tg of the urethane resin is 60° C. or lower. In this case, since the adhesion between the pigment, the resin and the paper is enhanced, the fixability is improved.

-Styrene acrylic resin-
By including the styrene-acrylic resin in the ink of the present embodiment, improvement in image quality and improvement in abrasion resistance can be obtained. Furthermore, the effect of the styrene-acrylic resin can further suppress the occurrence of blocking due to winding or stacking after printing.

The volume average particle size of the styrene-acrylic resin is preferably 40 nm or more and 60 nm or less. When the thickness is 40 nm or more and 60 nm or less, unevenness of the printed surface can be suppressed, and the surface can be smoothed to improve gloss, and OD (optical density) and chroma can be improved. Further, by setting the amount within the above range, not only can high image quality be obtained, but also fixability can be improved.
The molecular weight is not particularly limited and can be selected depending on the purpose.

From the viewpoint of ensuring fixability and improving image quality, the styrene acrylic resin is preferably contained in the ink in an amount of 1.0% by mass or more and 10.0% by mass or less, and 1.5% by mass or more and 10.0% by mass or less. More preferably included. Moreover, by making it 1.0% by mass or more, the effect of suppressing surface unevenness is obtained, and the effect of improving scratch resistance is also obtained. By making it 10.0% by mass or less, the occurrence of blocking can be further suppressed.

Moreover, as for the content in the ink, it is preferable that the styrene-acrylic resin is contained in a larger amount than the urethane resin. When the styrene-acrylic resin is contained more than the urethane resin, blocking and beading can be further suppressed, and image quality and fixability can be further improved.

－Other resins－
In addition to urethane resins and styrene-acrylic resins, other resins can be added depending on the purpose. For example, polyester resins, acrylic resins, vinyl acetate resins, styrene resins, butadiene resins, styrene-butadiene resins, vinyl chloride resins , acrylic silicone 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.

The volume average particle diameter of the other resin is not particularly limited and can be appropriately selected according to the purpose. It is more preferably 10 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 100 nm or less.

-Measurement of volume average particle size-
The volume average particle diameter can be measured, for example, using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

<<Pigments>>
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 as pigments.
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, quinophthalone 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.

Dyes can be used as coloring materials other than pigments.
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.
As a dye, for example, 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 pigment in the ink is preferably 0.1% by mass or more and 25% by mass or less, more preferably 1% by mass or more and 20% by mass or less, from the viewpoints of improving image density, good fixability, and ejection stability. is.

<<Method of Dispersing Pigment>>
As a method of dispersing the pigment to obtain an 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 the pigment, and a method of dispersing the pigment using a dispersant. method, etc.
As a method of making a self-dispersing pigment by introducing a hydrophilic functional group into a pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon) to make it dispersible in water. is mentioned.
As a method of coating the surface of a pigment with a resin and dispersing it, there is a method of encapsulating the pigment in microcapsules to make it dispersible in water. 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.
As a dispersant, 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.

<<Preparation of pigment>>
Inks can be obtained by mixing materials such as water and organic solvents with pigments. 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 mixing and 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. 50% by mass or less is preferable, and 0.1% by mass or more and 30% by mass or less is more preferable.
It is preferable to filter coarse particles with a filter, a centrifugal separator, or the like, and deaerate the pigment dispersion, if necessary.

<<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 polyhydric alcohols 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- 1,3-pentanediol, petriol and the like.
Examples of polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether and the like.
Examples of polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Nitrogen-containing heterocyclic compounds include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone and the like. mentioned.
Amides include formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide and the like.
Amines include monoethanolamine, diethanolamine, triethylamine, and the like.
Examples of sulfur-containing compounds include dimethylsulfoxide, sulfolane, thiodiethanol and the like.
Other organic solvents include propylene carbonate and ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250° C. or less because it not only functions as a wetting agent but also provides good drying properties.

As the organic solvent, polyol compounds having 8 or more carbon atoms and glycol ether compounds are also 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. % or more and 60 mass % or less is more preferable.

<<Additives>>
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 preferred. Examples of silicone-based surfactants include side chain-modified polydimethylsiloxane, both-end-modified polydimethylsiloxane, single-end-modified polydimethylsiloxane, and side-chain both-end-modified polydimethylsiloxane. Those having a polyoxyethylene group or a polyoxyethylene-polyoxypropylene group as a modifying 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 perfluoroalkylsulfonic acid compounds include perfluoroalkylsulfonic acids, perfluoroalkylsulfonates, and the like. Examples of perfluoroalkylcarboxylic acid compounds include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. Examples of polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains include sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in side chains, and polyoxyalkylene ether polymers having perfluoroalkyl ether groups in side chains. Examples thereof include salts of oxyalkylene 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 ends, and polyether-modified silicone surfactants having polyoxyethylene groups or polyoxyethylene polyoxypropylene groups as modifying groups are particularly preferred because they exhibit good properties as water-based surfactants. .
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, in 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.)
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 (Momentive Japan) and the like.

As the fluorosurfactant, a fluorine-substituted compound having 2 to 16 carbon atoms is preferable, and a fluorine-substituted compound having 4 to 16 carbon atoms is more preferable.
Examples of fluorine-based surfactants include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain is preferable because of its low foamability, and in particular, fluorine-based compounds represented by general formulas (F-1) and (F-2) Surfactants are preferred.

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

In the compound represented by the general formula (F-2), Y is H, or C _m F _2m+1 and m is an integer of 1 to 6, or CH ₂ CH(OH)CH ₂ —C _m F _2m+1 and m is An integer from 4-6, or CpH _2p+1 where p is an integer from 1-19. n is an integer of 1-6. a is an integer from 4 to 14;
Commercially available products may be used as the fluorosurfactant. Examples of 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.); Fleurard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (both manufactured by Sumitomo 3M); Megafac F-470, F -1405, F-474 (both manufactured by Dainippon Ink and Chemicals); 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 Chemours); 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), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.) Among these, Chemours FS-3100, FS-34, FS- 300, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omnova Co., Ltd., and Unidyne DSN- manufactured by Daikin Industries, Ltd. 403N is particularly preferred.

A fluorine-based surfactant represented by the following general formula (1) is particularly preferable as the surfactant contained in the ink. Note that n is an integer from 1 to 40.

By using the surfactant represented by the general formula (1), the wettability to the recording medium can be further improved, and more uniform ink wettability can be imparted to the recording medium. A more robust image quality can be obtained.

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.

<< Defoamer >>
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.

<< Antiseptic 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.

<<Physical properties of ink>>
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 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.

<Processing liquid>
The treatment liquid of the present invention contains a polyvalent metal salt and, if necessary, water, an organic solvent, a surfactant, an antifoaming agent, a pH adjuster, an antiseptic antifungal agent, an antirust agent and the like. Water, organic solvents, surfactants, antifoaming agents, pH adjusters, antiseptic antifungal agents, and antirust agents can be the same materials as those used for ink, and other materials used for known treatment liquids can be used. can.

<<Polyvalent metal salt>>
Polyvalent metal salts are composed of specific polyvalent metal ions having a valence of 2 or more and anions that bind to these polyvalent metal ions. The polyvalent metal salt used in this embodiment can function as an aggregating agent and has an action of aggregating solids.

Examples of polyvalent metal salts include magnesium salts, calcium salts, nickel salts, aluminum salts, boron salts, zinc salts and the like. Among them, magnesium salts and calcium salts are preferred, and magnesium salts are particularly preferred.
Calcium salts and magnesium salts include calcium chloride, magnesium chloride, calcium bromide, magnesium bromide, calcium nitrate, magnesium nitrate and magnesium sulfate.

In addition to the above, it may contain an organic acid metal salt.
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 polyvalent metal salt is preferably contained in the treatment liquid in an amount of 10% by mass or more and 40% by mass or less. When the content is 10% by mass or more, the effect of aggregating the solid content can be obtained, and the effect of suppressing color bleeding and beading is improved. By adjusting the content to 40% by mass or less, it is possible to suppress precipitation of polyvalent metal salts during evaporation of water.

<<Other physical properties>>
Further, in the present invention, the initial viscosity (X) of the treatment liquid and the viscosity (Y) of the treatment liquid at 10% water evaporation are
1.5≦(Y)/(X)≦4
is preferably satisfied. In this case, it is possible to suppress the fluctuation of defects due to the increase in viscosity caused by the evaporation factor.
Viscosity can be measured using, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.).

(recoding media)
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.

(recorded matter)
A recorded matter obtained by the present invention is formed on a recording medium using the ink set of the present invention.
A recorded matter can be obtained by recording with an inkjet recording apparatus and an inkjet recording method.

(Recording device, recording method)
The image forming method of the present invention includes a treatment liquid application step of applying the treatment liquid to a recording medium, and an ink application step of applying ink to the area of the recording medium to which the treatment liquid has been applied. Further, the image forming apparatus of the present invention has a treatment liquid application unit that applies the treatment liquid to the recording medium, and an ink application unit that applies ink to the areas of the recording medium to which the treatment liquid has been applied.
The ink set of the present invention can be suitably used for various recording apparatuses using an inkjet recording system, such as printers, facsimile machines, copiers, printer/fax/copier complex machines, stereolithography machines, and the like.
In the present invention, a recording apparatus and a recording method refer to an apparatus capable of ejecting ink, various treatment liquids, and the like onto a recording medium, and a method of performing recording using the apparatus. 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.

This recording apparatus can include not only a portion that ejects ink, but also devices called pre-processing devices and post-processing devices.
As an aspect of the pre-treatment device and the post-treatment device, it has a pre-treatment liquid and a post-treatment liquid in the same manner as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y). There is a mode in which a liquid container and a liquid ejection head are added, and the pretreatment liquid and the posttreatment liquid are ejected by an inkjet recording method.
As another aspect of the pre-treatment device and the post-treatment device, there is an aspect in which a pre-treatment device and a post-treatment device using a method other than the inkjet recording method, such as a blade coating method, a roll coating method, and a spray coating method, are provided.

It should be noted that the method of using the ink set is not limited to the ink jet recording method, and can be widely used. Other than the inkjet recording method, for example, blade coating method, gravure coating method, bar coating method, roll coating method, dip coating method, curtain coating method, slide coating method, die coating method, spray coating method and the like can be used.

The use of the ink set of the present invention is not particularly limited and can be appropriately selected according to the intended purpose. Furthermore, it can be used not only as an ink to form two-dimensional characters and images, but also as a three-dimensional modeling material for forming a three-dimensional three-dimensional image (three-dimensional object).
A known three-dimensional modeling apparatus for forming three-dimensional objects can be used, and is not particularly limited. be able to. The three-dimensional object includes a three-dimensional object obtained by applying ink repeatedly. It also includes a molded product obtained by processing a structure obtained by applying ink onto a base material such as a recording medium. Molded processed products are, for example, products obtained by subjecting recorded matter or structures formed in the form of sheets or films to molding processes such as heat stretching and punching. It is suitably used for applications where molding is performed after the surface is decorated, such as electronic devices, meters of cameras, and operation panels.

In the present invention, the terms image formation, recording, printing, and printing are all synonymous. The terms recording medium, medium, and printed material are all synonymous.

Next, one embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram of an inkjet recording apparatus to which the present invention is applied, which is an example of a line type apparatus.

An inkjet recording apparatus 300 to which the present invention is applied includes a recording medium conveying unit 301, a processing unit 302 that applies a treatment liquid to a recording medium 203, and a post-processing drying unit 303 that dries the recording medium 203 to which the treatment liquid has been applied. It has an image forming process section 304 with an ink containing section 310 . If necessary, post-treatment may be performed. Post-treatment step 305 applies post-treatment liquid to the recording medium after the image forming process, and post-treatment drying is performed to dry the recording medium 203 to which the post-treatment liquid has been applied. 306 may be provided.

The recording medium conveying unit 301 includes a paper feeding device 307 , a plurality of conveying rollers, and a winding device 308 . The recording medium 203 shown in FIG. 3 is a roll of continuous paper (roll paper). The recording medium 203 is unwound from a paper feeding device by a conveying roller, conveyed on a platen, and wound by a winding device. be taken.

The processing liquid is applied to the recording medium 203 conveyed from the recording medium conveying unit 301 by the processing unit 302 in FIG. By applying a treatment liquid that has the function of aggregating ink before forming an image on a recording medium, bleeding, density, color tone, and show-through can be prevented even when forming images on media other than dedicated inkjet paper. etc. are avoided, image fastness such as water resistance and weather resistance is excellent, and image quality can be improved.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Examples 1 to 18, Comparative Examples 1 to 7)
The following evaluations were performed using the inks and treatment liquids (ink sets) shown in the table below. In the table, the numerical values in the columns of ink and treatment liquid represent "% by mass".
For evaluation, before printing (before applying ink), the treatment liquid was applied to the recording medium using a wire bar (winding diameter: 0.02 mm) manufactured by Kobayashi Seisakusho Co., Ltd., and dried in an oven at 90° C. for 30 seconds. Immediately thereafter, printing (ink application) was performed.

Examples 1 to 10 are examples of a set of monochromatic inks of yellow, magenta, cyan, and black and a treatment liquid, and each ink is evaluated. On the other hand, Examples 11 to 17 are examples of a set of four color inks of yellow, magenta, cyan, and black and a treatment liquid, and are evaluated as a set of four color inks and a treatment liquid. In addition, Example 18 is an example of a set of three color inks of yellow, cyan, and black and a treatment liquid, and is evaluated as a set of three color inks and a treatment liquid. Comparative Examples 1 to 7 are comparative examples of a set of monochromatic inks of yellow, magenta, cyan, and black and treatment liquid, and each ink is evaluated.

In the following evaluation, when evaluating a set of four color inks and treatment liquids, when printing a solid image, the printing area is divided into four equal parts and each ink is applied to form a solid image. . Similarly, for a set of three color inks, a solid image is formed by dividing the printing area into three equal parts.

In the table, those shown below were used.
Pascal AD1: manufactured by Meisei Chemical Industry Co., Ltd. (volume average particle size: 15 nm, urethane resin, glass transition temperature Tg: about 50 ° C.)
・ Superflex 150: Daiichi Kogyo Seiyaku Co., Ltd. (volume average particle size: 100 nm, urethane resin, glass transition temperature Tg: 40 ° C.)
Movinyl 5450: manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (volume average particle size: 50 nm, styrene acrylic resin)
・ Movinyl 6969D: manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (volume average particle size of about 100 nm, styrene acrylic resin)
・ Capstone-FS3100: manufactured by Chemours (surfactant represented by the general formula (1))
・Capstone-FS34: manufactured by Chemours ・Surfinol 465: manufactured by Shin-Etsu Chemical Co., Ltd. ・Himax SC-506: manufactured by Hymo (cationic polymer)

(measurement)
<Dynamic surface tension>
The dynamic surface tension of each ink was measured using a portable surface tension meter (SITA DynoTester, manufactured by Eiko Seiki Co., Ltd.) under conditions of temperature: 25° C. and bubble life time: 15 msec.

<Static surface tension>
The static surface tension of each ink was measured at a temperature of 25° C. using a surface tensiometer (DY300, manufactured by Kyowa Kaimen Co., Ltd.).

(evaluation)
<Color Bleed>
Using a modified GXe5500 serial printer (manufactured by Ricoh Co., Ltd.), Lumi Art Gross 130 was selected for glossy paper, fine mode, and no color correction, solid images were printed, and color bleeding was visually determined.
For the evaluation of color bleeding, the patches shown in FIG. 4 were printed as a solid image, and bleeding at the boundary between adjacent inks of each color was evaluated. Single color ink sets or multiple color ink sets are evaluated depending on whether the focus is on each color or on the whole.

[Evaluation criteria]
A: Not at all.
B: Color bleeding can be confirmed from a distance of 30 cm.
C: Color bleeding can be confirmed even from a distance of 1 m.
D: Color bleeding can be confirmed even from a distance of 1.5 m or more.

<Beading>
Using GXe5500, Lumi Art Gloss 130 was selected as glossy paper, fine mode, and no color correction, a solid image was printed, and density unevenness (beading) 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.

<Ink Storage Stability>
Using E-550L (manufactured by Toki Sangyo Co., Ltd.: Cone 1°34' x R24), the viscosity (initial viscosity) before storage and the viscosity measured after storage at 70 ° C. for 14 days in a sealed container were stored. Stability was obtained according to the following formula, and the obtained values were evaluated based on the following criteria.
Storage stability = (viscosity after storage/initial viscosity) x 100

[Evaluation criteria]
A: within 100±5% B: over 100±5% to within ±7% C: over 100±7% to within ±10% D: over 100±10%

<Fixability>
A 6 cm square solid image was printed on Lumi Art Gross 130 using a printer (GXe5500) at a duty of 100, and 24 hours or more elapsed after printing. After that, the Lumi Art Gloss was attached to a crockmeter (manufactured by Toyo Seiki Co., Ltd.), and this was reciprocated 10 times against the solid portion obtained as described above. OD (optical density) was measured and evaluated according to the following criteria.

[Evaluation criteria]
A: Transfer OD is less than 0.05 B: Transfer OD is 0.05 or more and less than 0.15 C: Transfer OD is 0.15 or more and less than 0.20 D: Transfer OD is 0.20 or more

<Blocking>
A printer (GXe5500) was used on Lumi Art Gross 130 to carry out solid printing of 6 cm square, followed by oven drying at 90° C. for 30 seconds. Next, the printed surfaces were overlapped and sandwiched between ^two 10 cm x 10 cm square glass plates. I left it. Evaluation was made according to the following criteria.

[Evaluation criteria]
A: No blocking B: Slightly blocking (a slight transfer portion is confirmed on the interleaving paper)
C: Considerable blocking (Transfer part is clearly confirmed on the interleaving paper)
D: Completely blocking (adhesion is difficult to peel off)

<Acceptance Criteria>
The obtained evaluation results were A for color bleeding, B or higher for beading, A for storage stability, and B or higher for fixability and blocking, which are at a level that poses no problems in actual use.

203 recording medium 300 inkjet recording device 301 recording medium conveying unit 302 processing unit 303 post-processing drying unit 304 image forming unit 305 post-processing unit 306 post-processing drying unit 307 paper feeding device 308 winding device 310 ink storage unit 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 Black (K), cyan (C), magenta (M), 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. 5480446

Claims (14)

a treatment liquid to be applied to a recording medium and ink to be applied to the recording medium to which the treatment liquid has been applied;
The treatment liquid contains a polyvalent metal salt,
The ink contains urethane resin, styrene-acrylic resin and pigment,
The static surface tension (B) of the ink and the static surface tension (C) of the treatment liquid are
0.5≦(B)/(C)≦0.7
The filling,
The 15 ms dynamic surface tension (D) of the treatment liquid and the 1500 ms dynamic surface tension (E) of the treatment liquid are
0.5≦(E)/(D)≦0.9
35 [mN/m] ≤ (E) ≤ 55 [mN/m]
A set of treatment liquid and ink characterized by filling 2. The set of treatment liquid and ink according to claim 1, wherein the urethane resin has a volume average particle size of 10 nm or more and 30 nm or less. 3. The set of treatment liquid and ink according to claim 1, wherein the styrene acrylic resin has a volume average particle size of 40 nm or more and 60 nm or less. 4. The set of treatment liquid and ink according to claim 1, wherein the polyvalent metal salt is one or more selected from magnesium salts and calcium salts. 5. The set of treatment liquid and ink according to claim 1, wherein the polyvalent metal salt is contained in the treatment liquid in an amount of 10% by mass or more and 40% by mass or less. 6. The set of treatment liquid and ink according to claim 1, wherein the urethane resin is contained in the ink in an amount of 1.0% by mass or more and 5.0% by mass or less. 7. The treatment liquid and ink set according to claim 1, wherein the styrene-acrylic resin is contained in the ink in an amount of 1.0% by mass or more and 10.0% by mass or less. 8. The set of treatment liquid and ink according to claim 1, wherein the ink contains a surfactant represented by the following general formula (1).

(In general formula (1), n represents an integer of 1 to 40.) The set of treatment liquid and ink according to any one of claims 1 to 8, wherein the urethane resin has a glass transition temperature Tg of 60°C or less. The 15 ms dynamic surface tension of the ink (A) and the static surface tension of the ink (B) are
1.5≦(A)/(B)≦2
10. The set of treatment liquid and ink according to any one of claims 1 to 9, wherein: The initial viscosity (X) of the treatment liquid and the viscosity (Y) at 10% moisture evaporation of the treatment liquid are
1.5≦(Y)/(X)≦4
11. The set of treatment liquid and ink according to any one of claims 1 to 10, wherein: 12. The treatment liquid and ink set according to any one of claims 1 to 11, wherein the ink is composed of three or more colors of ink including black ink, cyan ink and yellow ink. a treatment liquid application step of applying the treatment liquid to the recording medium;
an ink applying step of applying ink to the area of the recording medium to which the treatment liquid has been applied;
The treatment liquid contains a polyvalent metal salt,
The ink contains urethane resin, styrene-acrylic resin and pigment,
The static surface tension (B) of the ink and the static surface tension (C) of the treatment liquid are
0.5≦(B)/(C)≦0.7
The filling,
The 15 ms dynamic surface tension (D) of the treatment liquid and the 1500 ms dynamic surface tension (E) of the treatment liquid are
0.5≦(E)/(D)≦0.9
35 [mN/m] ≤ (E) ≤ 55 [mN/m]
An image forming method characterized by satisfying a processing liquid;
ink and
a treatment liquid applying means for applying the treatment liquid to a recording medium;
an ink applying means for applying the ink to the area of the recording medium to which the treatment liquid has been applied;
The treatment liquid contains a polyvalent metal salt,
The ink contains urethane resin, styrene-acrylic resin and pigment,
The static surface tension (B) of the ink and the static surface tension (C) of the treatment liquid are
0.5≦(B)/(C)≦0.7
The filling,
The 15 ms dynamic surface tension (D) of the treatment liquid and the 1500 ms dynamic surface tension (E) of the treatment liquid are
0.5≦(E)/(D)≦0.9
35 [mN/m] ≤ (E) ≤ 55 [mN/m]
An image forming apparatus characterized by satisfying

Images