JP7081634B2 - Recording method - Google Patents

Description

The present invention relates to an ink set and a recording method using the ink set.

The inkjet recording method is a relatively simple device that can record high-definition images, and is rapidly developing in various fields. For example, Patent Document 1 describes for inkjet printing for the purpose of image formation such as ink jet characteristics and realization of formation of a white image having high concealing property when forming a white image by using an inkjet recording method. It is disclosed that recording is performed using an ink composition containing titanium dioxide sol and a reaction solution containing magnesium sulfate on an OHP sheet.

Japanese Unexamined Patent Publication No. 2002-103783

However, when recording is performed on a non-absorbent recording medium or a low-absorbency recording medium using the inkjet recording method described in Patent Document 1, a color image is recorded on a white image using color ink. , There is a problem that bleeding of color ink occurs.

Further, in order to suppress bleeding, a method of heating the recording medium instead of using the reaction solution can be considered. However, if the recording medium is heated without using the reaction solution, high heating energy is required and there is a problem that clogging occurs.

The present invention has been made to solve at least a part of the above-mentioned problems, and when a plurality of inks are superimposed and recorded on a non-absorbent recording medium or a low-absorbability recording medium, those of them are recorded. It is an object of the present invention to provide an ink set that can prevent bleeding between inks and is less likely to be clogged.

The present inventors have diligently studied to solve the above problems. As a result, they have found that the above problems can be solved if the ink set contains a predetermined pretreatment liquid separately from the plurality of inks for the non-absorbent recording medium or the low absorption recording medium. The present invention has been completed.

That is, the present invention is as follows.
[1]
A reaction liquid containing a flocculant, a first ink containing a coloring material, and a second ink containing a coloring material are provided.
It is used for recording on a non-absorbent recording medium or a low-absorbency recording medium.
The reaction solution, the first ink, and the second ink are applied to the recording medium in this order and used.
Ink set.
[2]
At least one of the first ink and the second ink is a color ink containing a color material or a black ink containing a black color material.
The ink set described in the previous item [1].
[3]
The other of the first ink and the second ink is a white ink containing a white color material or a metallic ink containing a metallic color material.
The ink set described in the previous section [2].
[4]
The flocculant comprises at least one selected from the group consisting of polyvalent metal salts and organic acids.
The ink set according to any one of the above items [1] to [3].
[5]
The ratio (coloring material) of the number of moles (unit: mol) of the polyvalent metal salt contained in the reaction solution to the total mass (unit: g) of the coloring material contained in the first ink and the second ink. : Polyvalent metal salt) is 1000: 1 to 31000: 1.
The ink set described in the previous section [4].
[6]
The ratio of the number of moles (unit: mol) of the organic acid contained in the reaction solution to the total mass (unit: g) contained in the coloring materials of the first ink and the second ink (coloring material: organic acid). ) Is 800: 1 to 5500: 1.
The ink set according to the preceding item [4] or [5].
[7]
The first ink is a white ink containing a white color material or a metallic ink containing a metallic color material.
The second ink is a color ink containing a color material or a black ink containing a black color material.
The ink set according to any one of the above items [1] to [6].
[8]
The surface tension of the reaction solution is 55 mN / N or less at 25 ° C.
The ink set according to any one of the above items [1] to [7].
[9]
The reaction solution further contains a component that becomes a receiving layer of the ink to be applied next to the reaction solution, and at least one selected from the group consisting of a cationic resin.
The ink set according to any one of the above items [1] to [8].
[10]
At least one selected from the group consisting of the receiving layer component contained in the reaction solution and the cationic resin (unit: g), and the coloring material (unit: g) contained in the first ink. The mass ratio with and (color material: at least one selected from the group) is 7: 1 to 70: 1.
The ink set described in the previous section [9].
[11]
The recording method using the ink set according to any one of the above items [1] to [10].
A reaction solution applying step of applying the reaction solution contained in the ink set to a non-absorbent recording medium or a low-absorbency recording medium, and a reaction liquid application step.
The first step of applying the first ink contained in the ink set to the region to which the reaction solution is applied, and
A second step of applying the second ink contained in the ink set to the area to which the first ink is applied, and
The recording method.
[12]
Volatilization of the volatile components contained in the reaction solution and the first ink on the non-absorbable recording medium or the low-absorbing recording medium after the first step and before the second step. The amount is 95% by mass or less with respect to 100% by mass of the total mass of the volatile components contained in the reaction solution and the first ink before application.
The recording method according to the preceding paragraph [11].
[13]
The number of moles (unit: mol) of the polyvalent metal salt contained in the reaction solution per unit area of the non-absorbable recording medium or the low-absorbing recording medium, and the first ink and the second ink. The ratio (color material: polyvalent metal salt) to the total mass (unit: g) of the color material contained in is 1000: 1 to 31000: 1.
The recording method according to the preceding paragraph [11] or [12].
[14]
The number of moles (unit: mol) of the organic acid contained in the reaction solution per unit area of the non-absorbable recording medium or the low-absorbing recording medium, and the first ink and the second ink. The ratio (coloring material: organic acid) to the total mass (unit: g) of the coloring material is 800: 1 to 5500: 1.
The recording method according to any one of the preceding paragraphs [1] to [13].
[15]
From the components of the reaction solution, which are the receiving layers of the first ink and the second ink, and the cationic resin per unit area of the non-absorbable recording medium or the low-absorbing recording medium. The ratio of the mass (unit: g) of at least one selected from the group to the mass (unit: g) of the coloring material contained in the first ink (coloring material: at least one selected from the group) is 7: 1 to 70: 1,
The recording method according to any one of the preceding paragraphs [11] to [14].

It is a side view which shows the whole outline of the example of the inkjet recording apparatus which can be used in this embodiment.

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary, but the present invention is not limited thereto. Various modifications are possible within the range that does not deviate from the gist. In the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. Unless otherwise specified, the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown.

[Ink set]
The ink set according to the present embodiment includes a reaction solution containing a flocculant, a first ink containing a coloring material, and a second ink containing a coloring material, and is a non-absorbable recording medium or a low-absorbent recording medium. It is used for recording on a medium (hereinafter collectively referred to as “recorded medium”), and the reaction solution and the first ink are placed on the non-absorbable recorded medium or the low-absorbent recorded medium. , And the second ink are applied in this order. Hereinafter, the first ink and the second ink are collectively referred to as "ink".

[Reaction solution]
The reaction solution contains a flocculant. By using such a reaction solution, a high-quality recorded material can be obtained without heating the recording medium, and clogging of the nozzle due to drying of the nozzle due to heating of the recording medium is suppressed. be able to. Specifically, by containing the flocculant, the pigment contained in the first ink and the pigment contained in the second ink can be aggregated without heating, and the bleeding of the second ink can be prevented. This makes it possible to prevent the first ink from being stuck, and it is possible to obtain a high-quality recorded material.

(Coagulant)
The flocculant is not particularly limited, but preferably contains at least one selected from the group consisting of polyvalent metal salts and organic acids.

(Multivalent metal salt)
The polyvalent metal salt is not particularly limited, but for example, a polyvalent metal salt of an inorganic acid or a polyvalent metal salt of an organic acid is preferable. Such polyvalent metal salts are not particularly limited, but are, for example, group 2 alkaline earth metals in the periodic table (for example, magnesium and calcium) and group 3 transition metals in the periodic table (for example, lanterns). , Salts of Group 13 earth metals (eg, aluminum), lanthanides (eg, neodymium), of the Periodic Table. Suitable salts of these polyvalent metals include carboxylates (such as formic acid, acetic acid and benzoate), sulfates, nitrates, chlorides and thiocyanates. Among them, preferably, calcium salt or magnesium salt of carboxylic acid (calcium, acetic acid, benzoate, etc.), calcium salt or magnesium salt of sulfuric acid, calcium salt or magnesium salt of nitrate, calcium chloride, magnesium chloride, and thiosian acid. Calcium salt or magnesium salt can be mentioned. The polyvalent metal and the salt constituting the polyvalent metal salt may be any combination thereof, or may be a hydrate. The polyvalent metal salt may be used alone or in combination of two or more.

The content of the polyvalent metal salt is preferably 0.5 to 5% by mass, more preferably 0.5 to 4% by mass, still more preferably 1 to 4% by mass, based on 100% by mass of the total mass of the reaction solution. .. When the content of the polyvalent metal salt is within the above range, the bleed resistance of the obtained recorded material tends to be better.

(Organic acid)
The organic acid is not particularly limited, and examples thereof include phosphoric acid, oxalic acid, malonic acid, succinic acid, citric acid, and acetic acid. Of these, monovalent or divalent or higher carboxylic acids are preferable. By including such a carboxylic acid, the bleed resistance of the obtained recorded material tends to be better. The organic acid may be used alone or in combination of two or more. Further, the organic acid may be in the form of a salt. The organic acid salt is not particularly limited, and examples thereof include the salt of the organic acid (however, it does not overlap with the polyvalent metal salt). The salt of the organic acid is not particularly limited, and examples thereof include sodium acetate and the like. The organic acid salt may be used alone or in combination of two or more.

The content of the organic acid is preferably 1 to 15% by mass, more preferably 1 to 14% by mass, still more preferably 1 to 7% by mass, based on 100% by mass of the total mass of the reaction solution. When the content of the organic acid is within the above range, the bleed resistance of the recorded material obtained tends to be more excellent.

Further, at least one selected from the group consisting of a component in which the reaction solution serves as a receiving layer for at least one of the first ink and the second ink (hereinafter, also simply referred to as “receptive layer component”) and a cationic resin. It is preferable to include it.

(A component that serves as a receiving layer for at least one of the first ink and the second ink)
Since the reaction solution contains the receptive layer component, it tends to be more excellent in bleeding resistance and color development property of the obtained recorded material. The receiving layer component is not particularly limited, and examples thereof include inorganic fine particles and solid fine particles in a liquid containing resin fine particles solid in the liquid. Examples of such particles include cationic particles, nonionic particles, and anionic particles. Among these, those in which gaps remain between the fine particles in a state of being adhered to the recording medium to form a coating film are preferable. The “gap” refers to a void in a state where the coating film of the reaction solution is dry. When the reaction solution is applied to the recording medium to form a coating film, gaps are formed in the coating film due to the components that serve as the receiving layer, and at least the ink applied next to the reaction solution is absorbed by the gaps, resulting in bleeding. Is more preferable in that The component to be the receiving layer is usually at least a component to be a receiving layer of the first ink, and may be a receiving layer of the second ink to be applied next.

Since the particles are cationic, they have the effect of forming a layer for receiving the first ink and the second ink and imparting aggregation. The cationic particles are not particularly limited, and examples thereof include Snowtech ST-AK (trade name manufactured by Nissan Chemical Industries, Ltd.).

The anionic or nonionic nature of the particles forms a layer that receives the first and second inks. The anionic particles or nonionic particles are not particularly limited, and examples thereof include anionic colloidal silica. Examples of commercially available products include Snowtex ZL (trade name manufactured by Nissan Chemical Industries, Ltd.).

The content of the receiving layer component is preferably 0.1 to 10% by mass, more preferably 0.1 to 6% by mass, based on 100% by mass of the total mass of the reaction solution. When the content of the receptive layer component is within the above range, the obtained recorded material tends to be more excellent in bleeding resistance and color development. The receiving layer component may be used alone or in combination of two or more.

(Cationic resin)
Since the reaction solution contains a cationic resin, the bleeding resistance and color development property of the obtained recorded material tend to be superior. The cationic resin is not particularly limited, and examples thereof include a resin soluble in a reaction solution and a resin showing a dispersed state in a solution such as a resin emulsion. The cationic resin acts as an auxiliary agent for the flocculant rather than the flocculant because the interaction with the pigment contained in the first ink and the second ink is relatively weak as compared with the above-mentioned flocculant. A resin that is soluble in the reaction solution is preferable because of its excellent interaction.

The resin soluble in the reaction solution is not particularly limited, and examples thereof include amine-based resins, and examples thereof include polyallylamine and polyallylamine derivatives.

The resin emulsion is not particularly limited, and examples thereof include polyolefin-based resins, urethane-based resins, acrylic-based resins, and polyester-based resins. For example, a resin emulsion that can be contained in an ink described later can be mentioned, and examples of commercially available products include Arrow Base CD-1200 (trade name manufactured by Unitika, polyolefin-based resin), which is preferable.

The content of the cationic resin is preferably 0.1 to 10% by mass, more preferably 0.1 to 6% by mass, based on 100% by mass of the total mass of the reaction solution. When the content of the cationic resin is within the above range, the recorded material tends to be more excellent in bleeding resistance and color development. The cationic resin may be used alone or in combination of two or more.

In addition to the above, the reaction solution can contain a solvent, a surfactant, and the like.

〔solvent〕
The reaction solution in the present embodiment preferably further contains a solvent. The solvent is not particularly limited, but for example, an organic solvent or water can be used.

Examples of the water include pure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, and distilled water, and ultrapure water from which ionic impurities have been removed as much as possible. Further, when water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide or the like is used, it is possible to prevent the growth of mold and bacteria when the reaction solution is stored for a long period of time. This tends to further improve storage stability.

The water content is preferably 80 to 95 parts by mass, more preferably 85 to 95 parts by mass with respect to 100 parts by mass of the reaction solution. When the water content is within the above range, the viscosity tends to be lower.

As the organic solvent, a volatile water-soluble organic solvent is more preferable. The organic solvent is not particularly limited, but specifically, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,2. -Pentylene diol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol Mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monobutyl ether, diethylene glycol mono-t-butyl ether, propylene glycol monomethyl ether, propylene glycol Monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol Mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol ethylmethyl ether, diethylene glycol butylmethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dipropylene Glycol dimethyl ether, dipropylene glycol diethyl ether, tripropylene glycol dimethyl ether, methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2 -Alcohols or glycols such as pentanol, 3-pentanol, and tert-pentanol, N, N-dimethylformamide, N, N-dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, 2- Oxazoridone, 1,3-dimethyl-2-imidazolidinone, dimethylsulfoxide, Sulfolane and 1,1,3,3-tetramethylurea can be mentioned.

The organic solvent may be used alone or in combination of two or more. The content of the organic solvent is not particularly limited and can be appropriately determined as needed. Among these, it is preferable to use one or more selected from the group consisting of 1,2-hexanediol, triethylene glycol monobutyl ether, and dipropylene glycol monopropyl ether.

The content of the organic solvent is preferably 1 to 10% by mass with respect to 100% by mass of the total mass of the reaction solution.

[Surfactant]
The reaction solution used in this embodiment preferably contains a surfactant. The surfactant is not particularly limited, but for example, at least one selected from the group consisting of an acetylene glycol-based surfactant and a polysiloxane-based surfactant is preferable.

Among these, a polysiloxane-based surfactant is more preferable because the solubility in the reaction solution becomes large and foreign matter is less likely to be generated in the reaction solution.

The above-mentioned acetylene glycol-based surfactant is not particularly limited, but for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-. Select from 5-decyne-4,7-diol alkylene oxide adducts and 2,4-dimethyl-5-decyne-4-ol and 2,4-dimethyl-5-decyne-4-ol alkylene oxide adducts. One or more of them is preferable. These are E series such as Orfin 104 series and Orfin E1010 (trade name manufactured by Air Products Japan, Inc.), Orfin PD-002W, Surfinol 465 and Surfinol 61 (Nissin). It is available as a commercial product such as (trade name) manufactured by Chemical Industry CO., Ltd.).

The polysiloxane-based surfactant is not particularly limited, and examples thereof include BYK-347 and BYK-348 (trade names manufactured by BYK Japan KK).

The content of the above-mentioned surfactant is preferably 0.1 to 3% by mass with respect to 100% by mass of the total mass of the reaction solution.

The surface tension of the reaction solution is preferably 55 mN / N or less, more preferably 40 mN / N or less at 25 ° C. When the surface tension is within the above range, the reaction solution can be uniformly applied when recording on the recording medium. The lower limit of the surface tension of the reaction solution is not particularly limited, but is preferably 1 mN / N or more at 25 ° C. The surface tension can be measured by the method described in Examples.

[First ink]
The first ink contains a coloring material. The content of the coloring material in the first ink is preferably 15 to 2% by mass, more preferably 13 to 3% by mass, based on 100% by mass of the total mass of the first ink. When the content of the coloring material is within the above range, the bleeding resistance and the color developing property of the obtained recorded material tend to be more excellent.

[Second ink]
The second ink contains a coloring material. The content of the coloring material in the second ink is preferably 15 to 2% by mass, more preferably 13 to 3% by mass, based on 100% by mass of the total mass of the second ink. When the content of the coloring material is within the above range, the bleeding resistance and the color developing property of the obtained recorded material tend to be more excellent.

[Color material]
The color materials that can be contained in the first ink and the second ink will be described below. The first ink and the second ink may contain one kind of coloring material alone or two or more kinds of each. Further, the coloring material may be a dye or a pigment.

Examples of the black color material used for the black ink include carbon black, and the black color material is not particularly limited. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No. 2200B, etc. (above, manufactured by Mitsubishi Chemical Corporation), Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. Rega1 330R, Rega1 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. , Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color B1ack S150, Color Black S160, Color Black Def Examples thereof include Black 4A and Special Black 4 (all manufactured by Degussa).

The coloring material used for the white ink (white ink) is not particularly limited, but for example, C.I. I. Pigment Whites 6, 18 and 21. Other pigments used in white ink include sulfates of alkaline earth metals such as barium sulfate, carbonates of alkaline earth metals such as calcium carbonate, silicas such as fine powder silicic acid and synthetic silicates, and the like. Examples include metal compounds such as calcium silicate, alumina, alumina hydrate, titanium dioxide, and zinc oxide, as well as talc and clay.

The coloring material used for the yellow ink is not particularly limited, but for example, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, 180 can be mentioned.

The color material used for magenta ink is not particularly limited, but for example, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 , 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, or C.I. I. Pigment Violet 19, 23, 32, 33, 36, 38, 43, 50.

The coloring material used for the cyan ink is not particularly limited, but for example, C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16, 18, 22, 25, 60, 65, 66, C.I. I. Bat blue 4, 60 can be mentioned.

The color material other than magenta, cyan, and yellow is not particularly limited, but, for example, C.I. I. Pigment Green 7,10, C.I. I. Pigment Brown 3, 5, 25, 26, C.I. I. Pigment Orange 1,2,5,7,13,14,15,16,24,34,36,38,40,43,63.

Examples of the metallic coloring material used for the metallic ink include metallic pigments, and metal fine particles can be used, and examples of the metal include aluminum, aluminum alloy, and silver. The metallic ink is an ink in which the pattern applied to and formed on the recording medium has a metallic luster, and the metallic pigment is a pigment that develops a metallic luster.

It is preferable that at least one of the first ink and the second ink is a color ink containing a color material or a black ink containing a black color material. Further, one of the first ink and the second ink is a color ink containing a color material or a black ink containing a black color material, and the other of the first ink and the second ink is a white ink containing a white color material. It is more preferable to have. With such an ink set, when recording is performed on a non-absorbent recording medium or a low-absorbency recording medium, color development can be obtained with respect to a recording medium other than white. For example, transparent, color, metallic media and the like are preferably used.

It is preferable that the first ink is a white ink containing a white color material and the second ink is a color ink containing a color color material or a black ink containing a black color material. With such an ink set, when recording is performed on a non-absorbent recording medium or a low-absorbency recording medium, color development can be obtained with respect to a recording medium other than white. For example, transparent, color, metallic media and the like are preferably used.

The ratio A of the number of moles of the flocculant contained in the reaction solution (unit: mol) to the total mass (unit: g) of the coloring material contained in the first ink and the second ink is 100: 1 to 5000: 1. Is preferable, and 500: 1 to 4000: 1 is more preferable. When the ratio A is 100: 1 or more, precipitation of the reaction solution, cloudiness due to the reaction solution, stickiness, and generation of odor can be prevented. Further, when the ratio A is 5000: 1 or less, bleeding at the time of ink superposition can be suppressed.

The ratio B of the number of moles of the polyvalent metal salt contained in the reaction solution (unit: mol) to the total mass (unit: g) of the coloring material contained in the first ink and the second ink is 300: 1 to 5000. 1 is preferable, and 500: 1 to 5000: 1 is more preferable. When the ratio B is 300: 1 or more, precipitation of the polyvalent metal salt, cloudiness due to the polyvalent metal salt, stickiness, and generation of odor can be prevented. Further, when the ratio B is 5000: 1 or less, bleeding at the time of ink superposition can be suppressed.

The ratio C of the number of moles of organic acid (unit: mol) contained in the reaction solution to the total mass (unit: g) contained in the coloring materials of the first ink and the second ink is 100: 1 to 800: 1. Is preferable, and 100: 1 to 700: 1 is more preferable. When the ratio C is 100: 1 or more, precipitation of organic acid, cloudiness due to organic acid, stickiness, and generation of odor can be prevented. Further, when the ratio C is 800: 1 or less, bleeding at the time of ink superposition can be suppressed.

The mass (unit: g) of at least one selected from the group consisting of the receiving layer component and the cationic resin contained in the reaction solution, and the mass (unit: g) of the coloring material contained in the first ink. The ratio D is preferably 1: 1 to 10: 1, more preferably 1: 1 to 5: 1. When the ratio D is 1: 1 or more (the former), the function of suppressing the bleeding of the flocculant is more assisted, so that the bleeding tends to be further suppressed. Further, when the ratio D is 10: 1 or less (the former), it tends to be more excellent in storage stability of the reaction solution and clogging reliability when applied by inkjet.

As is clear from Table 2, in each of the above ratios, the ratio A is the ratio (coloring material: flocculant), the ratio B is the ratio (coloring material: polyvalent metal salt), and the ratio C is the ratio (coloring material: organic acid). ), The ratio D is a ratio (coloring material: at least one selected from the above group), and the ratios A to C are those in the reaction solution having a unit mass, the first ink having a unit mass, and the second ink having a unit mass. The ratio D is for the reaction solution having a unit mass and the first ink having a unit mass.

When a pigment is used as the coloring material, the pigment is a self-dispersing surface obtained by dispersing it in water with a dispersant or by using a chemical reaction on the surface of pigment particles to introduce a hydrophilic group. It is preferable to add it to the ink as a pigment dispersion obtained by dispersing the treated pigment in water or by dispersing the pigment coated with the polymer in water.

The dispersant is not particularly limited, and for example, a polymer dispersant (niwa, gelatin, casein, albumin proteins, arabic rubber, tragant rubber natural rubbers, saponin glucosides, alginic acid and propylene glycol ester, alginic acid). Triethanolamine, alginate fermented product of ammonium alginate, methyl cellulose, carboxylmethyl cellulose, cellulose derivative of ethyl hydroxy cellulose, polyvinyl alcohols, polypyrrolidones, polyacrylic acid, acrylic acid-acrylic nitrile copolymer, potassium acrylic acid-acrylic nitrile Polymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer acrylic resin, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid Ester copolymer, styrene-m-methylstyrene-acrylic acid copolymer styrene-acrylic resin, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-acrylic acid copolymer, acetic acid Vinyl acetate-based copolymer of vinyl-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-croton copolymer, vinyl acetate-acrylic acid copolymer And their salts) and polymers (various anionic surfactants, nonionic polymers, amphoteric polymers) can be used.

The self-dispersion type surface treatment pigment into which the above hydrophilic group is introduced can be dispersed or dissolved in water without a dispersant by surface treatment such that a carboxyl group and a salt thereof are directly bonded to the surface of the pigment. Is. Specifically, it can be obtained by grafting a functional group or a molecule containing a functional group onto the surface of a pigment by physical treatment of vacuum plasma or chemical treatment using an oxidizing agent of sodium hypochlorite or ozone. Can be done. The functional group grafted on one pigment particle may be single or multiple kinds. The type and degree of the functional group to be grafted may be appropriately determined in consideration of the dispersion stability in the ink, the color density, and the drying property on the front surface of the inkjet head.

The pigment coated with the polymer is not particularly limited, but for example, a monomer (copolymerizable monomer) that is copolymerizable with the dispersant after the pigment is dispersed using a dispersant having a polymerizable group. And, it can be obtained by carrying out emulsion polymerization in water using a photoradical polymerization initiator. Among this polymer, a monomer or oligomer having at least one selected from the group consisting of an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group as a double bond is according to a known polymerization method using a photoradical polymerization initiator. The polymerized one can be preferably used. The above emulsion polymerization can use a general method, and the polymerization proceeds by free radicals generated by thermal decomposition of a water-soluble photoradical polymerization initiator in the presence of an emulsifier.

The pigment and the dispersant constituting the pigment dispersion may be used alone or in combination of two or more.

[Resin emulsion]
When the ink used in this embodiment contains a pigment as a coloring material, it is preferable that the ink further contains a resin emulsion. By using the resin emulsion, as the ink dries, the resins in the resin emulsion, the resin, and the pigment are fused to each other to fix the pigment to the recording medium. The scratch resistance and adhesion can be further improved. Among the resin emulsions, urethane resin emulsions and acrylic resin emulsions are preferable, and urethane resin emulsions are more preferable. As a result, the fixing property of the ink becomes excellent, so that both the scratch resistance and the adhesion of the recorded material are excellent.

When the resin emulsion is contained in the ink, the resin emulsion forms a resin film on the recording medium to sufficiently fix the ink on the recording medium and improve the abrasion resistance of the recorded material. .. Therefore, it is preferable that the resin emulsion contains a thermoplastic resin. In particular, the urethane resin emulsion has a high degree of freedom in design, so that it is easy to obtain desired film physical properties.

Anionic resin emulsions are also preferred. The resin contained in the anionic resin emulsion is not particularly limited, and for example, (meth) acrylic acid, (meth) acrylic acid ester, acrylonitrile, cyanoacrylate, acrylamide, olefin, styrene, vinyl acetate, vinyl chloride, and the like. Examples include homopolymers or copolymers of vinyl alcohol, vinyl ether, vinyl pyrrolidone, vinyl pyridine, vinyl carbazole, vinyl imidazole, and vinylidene chloride, fluororesins, and natural resins. Among them, at least one selected from the group consisting of (meth) acrylic resin and styrene- (meth) acrylic acid copolymer resin is preferable, and it is selected from the group consisting of acrylic resin and styrene-acrylic acid copolymer resin. At least one is more preferable, and a styrene-acrylic acid copolymer resin is even more preferable. The above-mentioned copolymer may be in any form of a random copolymer, a block copolymer, an alternate copolymer, and a graft copolymer.

As the resin emulsion, one obtained by a known material and a production method may be used, or a commercially available product may be used. The commercial product is not particularly limited, but for example, Movinyl 966A (trade name manufactured by Nippon Synthetic Chemical Industry Co., Ltd., acrylic resin emulsion), Microgel E-1002, Microgel E- 5002 (trade name, manufactured by Nippon Paint Co., Ltd), Boncoat 4001, Boncoat 5454 (trade name, manufactured by DIC), SAE1014 (trade name, manufactured by Zeon Corporation), Cybinol SK-200 (trade name, manufactured by SAIDEN CHEMICAL INDUSTRY CO., LTD.), John Krill 7100, John Krill 390, John Krill 711, John Krill 511, John Krill 7001, John Krill 632, John Krill 741, John Krill 450, John Krill 840, John Krill 62J, John Krill 74J, John Krill HRC-1645J, John Krill 734, John Krill 852, John Krill 7600, John Krill 775, John Krill 537J, John Krill 1535, John Krill PDX-7630A, John Krill 352J, John Krill 352D, John Krill PDX-7145, John Krill 538J, John Krill 7640, John Krill 7641, John Krill 631, John Krill 790, John Krill 780, John Krill 7610 BASF), NK binder R-5HN (trade name manufactured by Shin-Nakamura Chemical Co., Ltd., acrylic resin emulsion, solid content 44%). Among these, mobile 966A, which is an acrylic resin emulsion, is preferable in order to sufficiently satisfy the preferable physical properties of the resin emulsion described above.

The resin emulsion may be used alone or in combination of two or more.

The resin content of the resin emulsion is preferably 3 to 15% by mass, more preferably 7 to 14% by mass, still more preferably 8 to 13% by mass, based on 100% by mass of the total mass of each ink. Within the above range, the adhesion and scratch resistance of the recorded material tend to be more excellent, the long-term storage stability of the ink is excellent, and the viscosity of the ink can be reduced in particular. It is in.

〔solvent〕
The ink in this embodiment preferably further contains a solvent. The solvent is not particularly limited, but for example, an organic solvent or water can be used.

Examples of the water include pure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, and distilled water, and ultrapure water from which ionic impurities have been removed as much as possible. Further, when water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide or the like is used, it is possible to prevent the growth of mold and bacteria when the ink is stored for a long period of time. This tends to further improve storage stability.

As the organic solvent, a volatile water-soluble organic solvent is more preferable. The organic solvent is not particularly limited, but specifically, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,2. -Pentylene diol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol Mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monobutyl ether, diethylene glycol mono-t-butyl ether, propylene glycol monomethyl ether, propylene glycol Monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol Mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol ethylmethyl ether, diethylene glycol butylmethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dipropylene Glycol dimethyl ether, dipropylene glycol diethyl ether, tripropylene glycol dimethyl ether, methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2 -Alcohols or glycols such as pentanol, 3-pentanol, and tert-pentanol, N, N-dimethylformamide, N, N-dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, 2- Oxazoridone, 1,3-dimethyl-2-imidazolidinone, dimethylsulfoxide, Sulfolane and 1,1,3,3-tetramethylurea can be mentioned.

The organic solvent may be used alone or in combination of two or more. The content of the organic solvent is not particularly limited and can be appropriately determined as needed. Among these, it is preferable to use one or more selected from the group consisting of 1,2-hexanediol, triethylene glycol monobutyl ether, and dipropylene glycol monopropyl ether.

[Surfactant]
The ink used in this embodiment preferably contains a surfactant. The surfactant is not particularly limited, but for example, at least one selected from the group consisting of an acetylene glycol-based surfactant and a polysiloxane-based surfactant is preferable. When the ink contains these surfactants, the drying property of the ink adhering to the recording medium is further improved, and high-speed recording becomes possible.

Among these, a polysiloxane-based surfactant is more preferable because the solubility in the ink becomes high and foreign matter is less likely to be generated in the ink.

The above-mentioned acetylene glycol-based surfactant is not particularly limited, but for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-. Select from 5-decyne-4,7-diol alkylene oxide adducts and 2,4-dimethyl-5-decyne-4-ol and 2,4-dimethyl-5-decyne-4-ol alkylene oxide adducts. One or more of them is preferable. These are E series such as Orfin 104 series and Orfin E1010 (trade name manufactured by Air Products Japan, Inc.), Orfin PD-002W, Surfinol 465 and Surfinol 61 (Nissin). It is available as a commercial product such as (trade name) manufactured by Chemical Industry CO., Ltd.).

The polysiloxane-based surfactant is not particularly limited, and examples thereof include BYK-347 and BYK-348 (trade names manufactured by BYK Japan KK).

[Moisturizer]
The ink used in this embodiment preferably further contains a moisturizer (wetting agent). As the moisturizer, any moisturizer generally used for inkjet ink can be used without particular limitation. The boiling point of the moisturizer is preferably 180 ° C. or higher, more preferably 200 ° C. or higher. When the boiling point is within the above range, good water retention and wettability can be imparted to the ink.

Specific examples of the high boiling point moisturizer are not particularly limited, but are limited to ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, and 2-ethyl-1. , 3-Hexenediol, 2-Methyl-2,4-Pentanediol, Tripropylene glycol, Polyethylene glycol with a number average molecular weight of 2000 or less, 1,3-Propylene glycol, Isopropylene glycol, Isobutylene glycol, Glycerin, Mesoerythritol, and Pentaerythritol can be mentioned.

The moisturizer may be used alone or in combination of two or more. Since the ink contains a moisturizer having a high boiling point, it is possible to obtain an ink that can maintain fluidity and redispersibility for a long time even if the pigment ink is left in contact with air in an open state. Further, such ink is less likely to cause clogging of the nozzle during restarting during recording using the recording device or after interruption, so that the ink ejection stability is excellent.

[Other ingredients]
The ink used in this embodiment has a dissolution aid, a viscosity regulator, and a pH in order to maintain good storage stability and ejection stability from the head, to improve clogging, or to prevent deterioration of the ink. Various additives such as regulators, antioxidants, preservatives, fungicides, corrosion inhibitors, and chelating agents for capturing metal ions that affect dispersion can also be added as appropriate. The ink used in this embodiment is preferably a water-based ink containing the largest amount of water among the volatile components, from the viewpoint of safety.

[Recorded medium]
The ink set according to this embodiment is used for recording on a non-absorbent recording medium or a low-absorbency recording medium. The absorbent recordable medium is inferior in water resistance and scratch resistance, and in the case of the absorbent recordable medium having an ink receiving layer provided on the surface, the cost may be high, whereas the absorbent recordable medium is non-absorbent. The recordable medium or the low-absorbency recordable medium is superior in terms of water resistance, scratch resistance, and low cost as the absorbent recordable medium having an ink receiving layer on the surface, but has low absorption and further. The more non-absorbent, the more likely it is that bleeding will occur, and it will be difficult to achieve both bleeding and printing speed. Therefore, it is advantageous to use the ink set according to this embodiment, and the non-absorbent recording medium is even more advantageous. be.

Here, the "low-absorbing recording medium" or "non-absorbable recording medium" refers to a recording medium having a water absorption amount of 10 mL / m ² or less from the start of contact to 30 msec in the Bristow method. .. This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Technical Association of the Pulp and Paper (JAPAN TAPPI). For details of the test method, refer to the standard No. of "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition". 51 "Paper and Paperboard-Liquid Absorption Test Method-Bristow Method".

The non-absorbent recording medium or the low-absorbability recording medium can also be classified according to the wettability of the recording surface with water. For example, 0.5 μL of water droplets are dropped on the recording surface of the recording medium, and the reduction rate of the contact angle (comparison between the contact angle at 0.5 msec and the contact angle at 5 seconds after landing) is measured. The medium can be characterized. More specifically, as a property of the recording medium, the non-absorbability of the "non-absorbable recording medium" means that the above-mentioned reduction rate is less than 1%, and the low absorption of the "low absorption recording medium". Gender refers to the above-mentioned reduction rate of 1% or more and less than 5%. Further, the absorbability means that the above-mentioned reduction rate is 5% or more. The contact angle can be measured using a portable contact angle meter PCA-1 (manufactured by Kyowa Interface Science Co., Ltd.) or the like.

The low-absorbency recording medium is not particularly limited, and examples thereof include coated paper provided with a coating layer for receiving oil-based ink on the surface. Specifically, it is a paper in which a paint is applied to the surface to improve the aesthetic appearance and smoothness, and is classified as a coated paper for printing in the "Production Dynamics Statistics Classification" of the Ministry of Economy, Trade and Industry. Examples of the paint include those made by mixing a white pigment, which is an inorganic compound such as clay (kaolin) or calcium carbonate, with an adhesive (binder) such as starch. The amount of the paint applied is preferably about 10 to 40 g / m ² . The coated paper is not particularly limited, and examples thereof include recording paper such as art paper, coated paper, and matte paper.

The non-absorbent recording medium is not particularly limited, but for example, a plastic film having no ink absorbing layer, a medium having a plastic coated on a substrate such as paper, or a medium having a plastic film adhered to the substrate. And so on. Examples of the plastic referred to here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, polyacrylic acid and the like.

Further, in addition to the above-mentioned recording medium, a plate of metals such as iron, silver, copper and aluminum, and an ink non-absorbent or low-absorbing recording medium such as glass can also be used.

〔Recording method〕
The recording method according to the present embodiment includes a reaction solution applying step of applying a reaction solution onto a non-absorbable recording medium or a low-absorbency recording medium using the above ink set, and a first ink from above the reaction solution. It has a first step of applying the ink and a second step of applying the second ink from above the first ink.

FIG. 1 is a side view showing an overall outline of an example of an inkjet recording apparatus 1 that can be used in the present embodiment. As shown in FIG. 1, the inkjet recording device 1 includes a feeding unit 10, a transport unit 20, a recording unit 30, a drying device 90, and a discharging unit 70 of the recording medium. Further, the inkjet recording device 1 also includes a preheater (not shown), and the recording medium F may be heated from the beginning.

Of these, the drying device 90 has a first drying unit 40 that performs a drying step of the recording medium, and a second drying unit 50 that dries the recorded material obtained by the recording method according to the present embodiment.

Further, the feeding unit 10 is provided so that the recorded medium F can be fed to the transporting unit 20. Specifically, the feeding unit 10 has a roll medium holder 11, and the roll medium holder 11 holds the recorded medium F. Then, by rotating the recorded medium F, the recorded medium F can be fed to the transport unit 20 on the downstream side in the feeding direction Y. The recording medium F is not limited to a roll shape.

Further, the transport unit 20 is provided so that the recorded medium F sent from the feed unit 10 can be transported to the recording unit 30. Specifically, the transport unit 20 has a first feed roller 21 and is configured to be able to further transport the transmitted recorded medium F to the recording unit 30 on the downstream side in the feed direction Y.

Further, the recording unit 30 is provided so that the reaction liquid can be applied to the recording medium F sent from the transport unit 20 and ink can be ejected for recording. Specifically, the recording unit 30 includes a head 31 for performing a reaction liquid application step, a head 32 for performing a first step, a recording head 33 for performing a second step, and a platen 34 as a medium support portion. .. The method of applying the reaction liquid and the ink is not limited to inkjet, and the reaction liquid may be applied by roller coating, spray coating, or the like. Inkjet is preferable because it is possible to apply the application position and the application amount to a required area with high accuracy.

Of these, the platen 34 is provided so that the recording medium F can be supported from the back surface. Further, the platen 34 is provided with a reaction liquid applied to the recording medium F and a first drying unit 40 for drying the ink ejected to the recording medium F. Further, a second feed roller 43 is provided on the downstream side of the platen 34 in the feed direction Y. The second feed roller 43 is configured to be able to feed the recorded recorded medium F to the second drying unit 50 on the downstream side in the feed direction Y.

Further, the second drying unit 50 is configured so that the reaction liquid applied to the recording medium F and the ink ejected to the recording medium F can be further dried. Further, a third feed roller 65 is provided in the vicinity of the outlet 64 of the second drying portion 50. The third feed roller 65 is arranged so as to be in contact with the back surface of the recorded medium F, and is configured to be able to feed the recorded medium F to the discharge unit 70 on the downstream side in the feed direction Y.

Further, the discharge unit 70 is provided so that the recorded medium F sent from the second drying unit 50 can be further sent downstream in the feed direction Y and discharged to the outside of the inkjet recording device 1. Specifically, the discharge unit 70 includes a fourth feed roller 71, a fifth feed roller 72, a sixth feed roller 73, a seventh feed roller 74, and a take-up roller 75. Of these, the fourth feed roller 71 and the fifth feed roller 72 are arranged so as to be in contact with the surface of the recording medium F. Further, the sixth feed roller 73 and the seventh feed roller 74 are arranged so as to form a roller pair. The recorded medium F discharged by the 6th feed roller 73 and the 7th feed roller 74 is provided so as to be wound by the take-up roller 75.

[Reaction solution applying step]
The reaction solution application step is a step of applying the reaction solution onto the non-absorbable recording medium or the low absorption recording medium. The applying means is not particularly limited, but for example, roller coating, spray coating, and inkjet coating can be used. It should be noted that the step of drying at least a part of the reaction solution applied to the recording medium during the reaction solution application step or after the reaction solution application step may be further provided.

The amount of the reaction solution to be applied to the recording medium is preferably 1 to 10 mg / inch ² , more preferably 1 to 5 mg / inch ² . When the amount of the reaction solution applied is within the above range, the bleed resistance of the obtained recorded material tends to be better.

The amount of the flocculant applied to the recording medium is preferably 0.5 × 10 ^-4 to 15 × 10 ^-4 mmol / inch ² (50 to 1500 nmol / inch ² ), preferably 0.65 × 10 ^-4 mmol / inch. ² or more is more preferable, 1 × 10 ^-4 mmol / inch ² or more is further preferable, 1.5 × 10 ^-4 mmol / inch ² or more is more preferable, and 2 × 10 ^-4 mmol / inch ² or more is further preferable. 3, 10 ^-4 mmol / inch ² or more is particularly preferable. Further, the imparting amount is more preferably 10.8 × 10 ^-4 mmol / inch ² or less, further preferably 10 × 10 ^-4 mmol / inch ² or less, and particularly preferably 5 × 10 ^-4 mmol / inch ² or less. When the amount of the flocculant applied is as described above, the image quality of the recorded material is further excellent, and it is preferable that the values of the ratio F to the ratio H described later are easily obtained. The amount of the reaction solution or coagulant applied is the amount of the reaction solution or coagulant applied per unit area in the region where the first ink and the second ink are applied in an overlapping manner.

[First step]
The first step is a step of applying the first ink from above the reaction solution. At this time, since the reaction solution and the first ink directly react with each other, the first ink can be rapidly aggregated, and the reaction solution does not have to be completely dried. Since the reaction solution does not have to be completely dried and the reaction solution does not have to be dried, the application of the first ink can be started early, and the recording speed can be increased. It should be noted that the step of drying at least a part of the reaction solution and the first ink applied to the recording medium during or after the first step may be further included.

The amount of the first ink applied in the first step is preferably 2 to 20 mg / inch ² , more preferably 15 to 5 mg / inch ² . When the amount of the first ink applied is within the above range, the obtained recorded matter tends to be more excellent in bleeding resistance, clogging reliability, and stickiness.

[Second step]
The second step is a step of applying the second ink from above the first ink. At this time, the reaction solution and the first ink do not have to be completely dried. By applying the second ink in a state where the first ink is not completely dried, the reaction liquid and the second ink can react even from above the first ink, and the reaction can occur. Even if the liquid and the first ink are not completely dried, the second ink can be applied while suppressing bleeding, and the recording speed can be increased. Prior to the second step, there may be a step of drying at least a part of the reaction solution and the first ink applied to the recording medium, and the step is to dry a part without completely drying. Is preferable. Further, it may have a step of drying the second ink applied to the recording medium during or after the second step.

The amount of the second ink applied in the second step is preferably 2 to 20 mg / inch ² , more preferably 15 to 5 mg / inch ² . When the amount of the first ink applied is within the above range, the obtained recorded matter tends to be more excellent in bleeding resistance, clogging reliability, and stickiness.

In the first step and the second step, the total amount (total mass) of the coloring materials contained in the first ink and the second ink per unit area in the region where the first ink and the second ink are superposed is determined. 0.5 to 3 mg / inch ² is preferable, 1 mg / inch ² or more is preferable, 1.5 mg / inch ² or more is more preferable, and 2.5 mg / inch ² or less is more preferable.

Further, in the first step, the total amount of the coloring material contained in the first ink applied per unit area in the region where the first ink and the second ink are applied in an overlapping manner is 0.1 to 2.5 mg / inch ² . Is preferable, 0.2 mg / inch ² or more is more preferable, 0.5 mg / inch ² or more is further preferable, 1 mg / inch ² or more is particularly preferable, and 2 mg / inch ² or less is more preferable. When each of the applied amounts is the above, the image quality of the recorded material and the like are further excellent, and it is preferable that the values of the ratios E to H, which will be described later, can be easily obtained.
The amount of each coloring material applied in the first and second steps, the total amount of coloring material applied, the amount of coagulant applied in the reaction liquid application step, and the ratios E to H described later are the first ink and the second ink. It is preferable that the area in which the total amount of the coloring material is applied is the area in which the total amount of the coloring material is applied in the area in which the above-mentioned materials are applied in an overlapping manner, in that the image quality of the recorded material can be further improved.

In the first step and the second step, the first ink or the second ink can be ejected from the nozzle of the line head or the serial head by the inkjet method and adhered to the recording medium. In the line method using a line head, the head is fixed and the recorded medium is moved along the sub-scanning direction (vertical direction and transport direction of the recorded medium), and in conjunction with this movement, from the nozzle opening of the head. An image can be recorded on the recording medium by ejecting ink droplets. Further, in the serial method using a serial head, the head is moved along the main scanning direction (horizontal direction and width direction of the recording medium), and ink droplets are ejected from the nozzle opening of the head in conjunction with this movement. This makes it possible to record an image on the recording medium.

In the second step, the volatile amount of the reaction liquid and the volatile components contained in the first ink at the time of applying the second ink to the non-absorbable recording medium or the low-absorbing recording medium is before the application. It is preferably 95% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less, based on 100% by mass of the total mass of the volatile components contained in the reaction solution and the first ink. Further, 60% by mass or less is even more preferable, 50% by mass or less is further particularly preferable, and 30% by mass or less is even more preferable in that the clogging reliability is excellent and the recording speed is also excellent. On the other hand, in terms of further excellent bleeding suppression, 5% by mass or more is preferable, 10% by mass or more is more preferable, 50% by mass or more is particularly preferable, and 60% by mass or more is even more preferable. Here, the “reaction solution before application” means the reaction solution of the reaction solution applied to the recording medium in the reaction solution application step before the reaction solution is applied, and is “the first ink before application”. Means the first ink of the first ink applied to the recording medium in the first step before the first ink is applied. When the volatile amount of the volatile component is 95% by mass or less, the reaction liquid and the second ink can efficiently react with each other, so that the recording speed can be increased. The amount of volatile components volatile can be determined by the method described in Examples.

The number of moles (unit: mol) of the flocculant contained in the reaction solution per unit area in the region where the first ink and the second ink are applied in an overlapping manner on the non-absorbable recording medium or the low-absorbing recording medium. The ratio E to the total mass (unit: g) of the coloring materials contained in the first ink and the second ink is preferably 800: 1 to 31000: 1, more preferably 800: 1 to 16000: 1, and 1600. 1 to 5100: 1 is more preferable. When the ratio E is 800: 1 or more, precipitation of the reaction solution, cloudiness due to the reaction solution, stickiness, and generation of odor can be prevented. When the ratio E is 31000: 1 or less, bleeding at the time of ink superposition can be suppressed. The ratio E can be controlled by the amount of the first ink, the second ink, and the reaction solution applied.

The number of moles (unit: mol) of the polyvalent metal salt contained in the reaction solution per unit area of the above-mentioned region of the non-absorbable recording medium or the low-absorbing recording medium, and the first ink and the second ink. The ratio F with the total mass (unit: g) of the coloring material is preferably 1000: 1 to 31000: 1, more preferably 1000: 1 to 15000: 1, and even more preferably 1000: 1 to 5100: 1. When the ratio F is 1000: 1 or more, precipitation of the polyvalent metal salt, cloudiness due to the polyvalent metal salt, stickiness, and generation of odor can be prevented. When the ratio F is 31000: 1 or less, bleeding at the time of ink superposition can be suppressed. The ratio F can be controlled by the amount of the first ink, the second ink, and the reaction solution applied.

The number of moles of organic acid (unit: mol) contained in the reaction solution and the color contained in the first ink and the second ink per unit area of the above-mentioned region of the non-absorbable recording medium or the low-absorbing recording medium. The ratio G to the total mass (unit: g) of the material is preferably 800: 1 to 5500: 1, more preferably 800: 1 to 1700: 1, and even more preferably 1000: 1 to 1700: 1. When the ratio G is 800: 1 or more, precipitation of organic acid, cloudiness due to organic acid, stickiness, and generation of odor can be prevented. When the ratio G is 5500: 1 or less, bleeding at the time of ink superposition can be suppressed. The ratio G can be controlled by the amount of the first ink, the second ink, and the reaction solution applied.

At least one mass (unit) selected from the group consisting of the receiving layer component contained in the reaction solution and the cationic resin per unit area of the above-mentioned region of the non-absorbable recording medium or the low-absorbing recording medium. : G) and the mass (unit: g) of the coloring material contained in the first ink are preferably 7: 1 to 70: 1, more preferably 7: 1 to 50: 1. When the ratio H is 7: 1 or more (the former), the bleeding suppression tends to be further excellent. When the ratio H is 70: 1 or less (the former), it tends to be more excellent in the application efficiency of the reaction solution. The ratio H can be controlled by the amount of the first ink and the reaction solution applied.

As is clear from Tables 3 to 5, in each of the above ratios, the ratio E is the ratio (coloring material: flocculant), the ratio F is the ratio (coloring material: polyvalent metal salt), and the ratio G is the ratio (coloring material:). Organic acid) and ratio H are ratios (coloring material: at least one selected from the above group).

In the recording method according to the present embodiment, the surface temperature of the recording medium in the first step and / or the second step is preferably 10 ° C. or higher and 65 ° C. or lower. Further, 50 ° C. or lower is more preferable, and 40 ° C. or lower is further preferable, in terms of further excellent clogging reliability. On the other hand, in terms of further excellent recording speed, 20 ° C. or higher is more preferable, 40 ° C. or higher is further preferable, and 50 ° C. or higher is particularly preferable. When the surface temperature of the recording medium is within the above range, clogging reliability and recording speed tend to be particularly excellent.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

[Materials for reaction liquids and inks]
The main materials for the reaction solution and ink used in the following examples and comparative examples are as follows.
[Pigment]
Titanium dioxide: Metal oxide NanoTek (R) Slurry Cyan pigment manufactured by C.I. Kasei Co., Ltd .: C.I. I. Pigment Blue 15: 3
[Multivalent metal salt]
Magnesium sulfate heptahydrate (molecular weight 246.47 g / mol)
Calcium acetate monohydrate (molecular weight 176.18 g / mol)
Calcium nitrate tetrahydrate (molecular weight 164.09 g / mol)
[Organic acid]
Succinic acid (molecular weight 118.09 g / mol)
[Surfactant]
BYK348 (Silicone-based surfactant, manufactured by Big Chemie Japan)
[Resin emulsion]
John Krill 62J (Acrylic styrene resin, manufactured by BASF)
[Receptive layer component]
Anionic colloidal silica ("Snowtex ZL" manufactured by Nissan Chemical Industries, Ltd.)
[Cationic resin]
Cationic resin emulsion (Unitika "Arrow Base CD-1200")
〔Organic solvent〕
1,2 hexanediol [moisturizer]
Propylene glycol

[Preparation of reaction solution and ink]
Each material was mixed in the composition (% by mass) shown in Table 1 below and sufficiently stirred to obtain a reaction solution, a first ink, and a second ink, respectively.

[Measurement method of surface tension]
The surface tension of the reaction solution was measured at a liquid temperature of 25 ° C. by the Wilhelmy method using a surface tension meter (manufactured by Kyowa Surface Science Co., Ltd., surface tension meter CBVP-Z, etc.).

[Preparation of ink set]
The obtained reaction solution, the first ink, and the second ink were combined as shown in Table 2 to obtain ink sets.

[Examples 1 to 18, Comparative Examples 1 to 5]
A modified machine of PX-G930 (manufactured by Epson) was used. The modification is that a heater is attached to the platen so that the recording medium can be heated. The nozzle pitch is 180 dpi. The ink set prepared above is ejected from each head in the order of the reaction solution, the first ink, and the second ink by the inkjet method under the recording conditions shown in Tables 1 to 3, and PET manufactured by Toray Industries, Inc., which is a non-absorbable recording medium. A solid pattern was adhered to the film "Lumirror S10" (trade name, thickness 100 μm) or NP coated paper (manufactured by Lintec), which is a low-absorbency recording medium. At this time, a pattern 1 to which only the reaction solution was applied, a pattern 2 to which only the reaction solution and the first ink were applied, and a pattern 3 to which the reaction solution, the first ink, and the second ink were applied to each other were formed. The patterns 2 and 3 were formed at the same time so as to be in contact with each other.

Specifically, in the case of forming the pattern 3, a pattern (sub) consisting of the reaction liquid is applied after adjusting the temperature of the recording medium with a heater so as to have the temperature in Tables 3 to 5 in advance. A pattern) is formed, then the first ink is applied onto the sub-pattern composed of the reaction solution to form a sub-pattern composed of the first ink, and then the sub-pattern composed of the first ink is composed of the second ink. A sub-pattern was formed to form pattern 3. The temperature of the recording medium was adjusted with a platen heater so that the temperatures shown in Tables 3 to 5 were maintained even during the application of the reaction solution, the first ink, and the second ink. Further, after the first step and before the start of the second step (at the start), the contents of the reaction liquid on the recording medium and the volatile components of the first ink are adjusted to be the values in Tables 3 to 5, and the second step is performed. The process was performed. The recording resolution was set to 720 × 720 dpi, and the amount of reaction liquid and the amount of ink per dot were adjusted so as to be the amount given in the table.

[Volatile amount of reaction liquid and volatile components of the first ink before the second step]
The volatile amounts of the reaction solution and the volatile components of the first ink in pattern 3 after the first step and before the second step (when the recording medium is conveyed to a position facing the second ink head) are as follows. Calculated in. Here, Af is the total amount (mg) of the reaction solution and the first ink to be applied to the recording medium in an overlapping manner. Further, Ae is the total residual amount of the reaction liquid and the first ink on the recording medium in a state where the reaction liquid and the first ink are dried (volatilized) to a state sufficient for using the recorded material. Further, A is the total mass of the reaction solution and the first ink on the recording medium immediately before the second step.
Volatile amount% of volatile components = ((Af-A) / (Af-Ae)) × 100

Af can be obtained from the ejection data of the printer and the mass per dot as the amount of the reaction liquid and the first ink applied in the pattern 3. A can be obtained by measuring the mass of the recorded medium at the time when the second ink is applied and the mass of the recorded medium before the reaction liquid application step and taking a difference. When measuring the volatile amount of the volatile component, it is convenient to use the recording medium prepared for the measurement. The measurement was performed by an electronic balance. At the time of measurement, the relationship between the drying time and the amount of volatilization when the reaction solution and the first ink are applied and then dried by heating with a platen is set. When recording with the recording device, the time from the application of the reaction solution and the first ink to the application of the second ink is defined as any time of the relationship between the drying time and the volatile amount obtained above. This makes it possible to obtain a desired volatile amount.

[evaluation]
[Bleed during superposition recording of the first ink and the second ink]
The amount of the second ink applied in the pattern 3 was changed between 30 and 200% with the values shown in Tables 3 to 5 as 100%, and recorded materials were obtained. The bleeding at the time of superposition recording of the first ink and the second ink was evaluated by visually observing the contact portion between the pattern 3 and the pattern 2 of the obtained recorded matter and evaluating them according to the following evaluation criteria. In addition, "200%" is a value assuming the maximum amount of the total of the inks of a plurality of colors when recording the colors of the secondary color or more by using the color inks of a plurality of colors. If it is A or AA according to the following evaluation criteria, it can be said that a recorded material in which bleeding is suppressed can be obtained even when a plurality of color inks are used.
(Evaluation criteria)
AA: There is no color mixing even when the amount of the second ink applied is 200%.
A: If the amount of the second ink applied is up to 100%, there is no color mixing.
B: If the amount of the second ink applied is up to 50%, there is no color mixing.
C: Color mixing occurs even when the amount of the second ink applied is 30%.

[Precipitation of reaction solution on the recording medium]
The precipitation of the reaction solution on the recording medium was evaluated by visually observing pattern 1 and using the following evaluation criteria.
(Evaluation criteria)
A: No precipitation is observed.
B: Precipitation is observed, but no cloudiness is observed.
C: Precipitation is observed and cloudiness is observed.

[White turbidity of the image part]
The white turbidity of the ink-applied portion (image portion) was evaluated by visually observing the pattern 3 and using the following evaluation criteria.
(Evaluation criteria)
A: No cloudiness is observed.
B: White turbidity is observed.

[Betamura of the first ink on the recording medium]
For Betamura of the first ink on the recording medium, pattern 2 was visually observed and evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: No uneven aggregation is observed in the first ink.
B: Some uneven aggregation is observed in the first ink.
C: A considerable amount of uneven aggregation is observed in the first ink.

[Odor of recorded material]
The odor of the recorded material was evaluated by sensory evaluation of pattern 3 according to the following evaluation criteria.
(Evaluation criteria)
A: There is no odor.
B: There is a slight odor.
C: Very odorous.

[Stickiness of recorded material]
The stickiness of the recorded material was evaluated by the following evaluation criteria by superimposing the pattern 3 on the printed surfaces.
(Evaluation criteria)
A: There is no sticking even if the two printed surfaces are left on top of each other for one day. (No stickiness)
B: If two printed surfaces are left on top of each other for one day and one is lifted, the two will stick to each other, but they will come off within one minute. (Slightly sticky,)
C: If two printed surfaces are left on top of each other for one day and one is lifted, the two will stick to each other, but they will not come off even after one minute or more. (It is sticky.)

[Recording speed]
The recording speed was evaluated according to the following evaluation criteria based on the recording speed at which pattern 3 was obtained.
(Evaluation criteria)
A: It can be recorded on one A4 size recording medium in less than 30 seconds.
B: It can be recorded on one A4 size recording medium in 30 seconds to 1 minute.
C: Recording can be performed on one A4 size recorded medium for more than 3 minutes.

[Clogged reliability]
The clogging reliability was evaluated by visually observing the nozzle after recording the pattern 3 on 50 A4 size recording media and using the following evaluation criteria.
(Evaluation criteria)
A: Nozzle omission and nozzle bending do not occur even if 50 sheets are recorded on the recording medium.
B: When 50 sheets are recorded on the recording medium, nozzle omission does not occur, but nozzle bending occurs.
C: When 50 sheets are recorded on the recording medium, nozzle omission and nozzle bending occur.

From the comparison between Examples and Comparative Examples 1 to 3, it was found that the ink set in which the reaction solution did not contain the flocculant was inferior in the effect of suppressing the bleeding of the second ink. Further, as a result of comparison between Examples and Comparative Example 4, when the reaction solution did not contain a flocculant, the effect of suppressing the bleeding of the second ink was improved by heating the recording medium to 70 ° C. It turned out to be clogged and inferior in reliability.

From Examples 1 to 4, it was found that bleeding was suppressed as the amount of the polyvalent metal salt used increased. It was also found that the smaller the amount of the multivalent metal salt used, the more the precipitation of the reaction solution on the recording medium and the white turbidity of the recorded material were suppressed. Further, from Examples 5 to 11, it was shown that there is a similar tendency even when other polyvalent metal salts or organic acids are used.

Furthermore, it was found from Examples 12 and 13 that bleeding was further suppressed by using a component serving as a receiving layer and a cationic resin. Further, by comparing Example 14 with other Examples and Comparative Examples 2 and 4, it was found that the lower the heat assist temperature, the better the clogging and reliability. Further, from Examples 2 and 14 to 16, it was found that bleeding tends to be suppressed when the volatile amount of the volatile component is high, but bleeding is suppressed when the volatile amount is not too high. It is presumed that this is because if the amount of volatilization is too high, the flocculant contained in the reaction solution cannot be sufficiently mixed onto the first ink, and the reaction between the second ink and the flocculant becomes difficult. .. It was also found that the lower the volatilization amount, the better the recording speed and the clogging reliability.

From Example 17, it was shown that the effect of the present invention is obtained even if the colors and whites of the first ink and the second ink are reversed. Further, from Examples 9 and 18, it was shown that the effect of the present invention can be obtained even with other recording media. When a low-absorbency recording medium was used, the bleeding tended to be more excellent, but on the other hand, the non-absorbent recording medium was more excellent in water resistance and abrasion resistance, so that the non-absorbable recording medium was more excellent. The present invention has been found to be more useful when used as a recording medium. Further, as a result of comparison between Example 19 and other examples, the higher the content of the surfactant in the reaction solution and the lower the surface tension, the more bleeding, the precipitation of the reaction solution on the recording medium, and the recorded matter. It was found that cloudiness was suppressed.

In the above example, recording is performed using a serial printer, but recording can also be performed using a line printer as shown in FIG. In this case, the time from when the reaction liquid and the first ink are applied by the reaction liquid application head and the first ink application head until the second ink is applied after being conveyed to the position facing the second ink head. It is possible to control the amount of volatilization of the recording medium by adjusting the speed at which the recording medium is conveyed.

Claims (15)

A reaction solution applying step of applying a reaction solution containing a flocculant to a non-absorbable recording medium or a low-absorbability recording medium, and a reaction solution application step.
The first step of applying the first ink containing the coloring material to the region to which the reaction solution is applied, and
The second step of applying the second ink containing the coloring material to the region to which the first ink is applied, and
Have,
The first ink is a white ink containing a white color material , and the second ink is a color ink containing a color color material or a black ink containing a black color material.
The reaction solution further contains a component serving as a receiving layer of the first ink and at least one selected from the group consisting of a cationic resin.
The component serving as the receiving layer of the first ink is anionic, inorganic fine particles or resin fine particles, and the cationic resin is a cationic resin emulsion.
The mass ratio of at least one selected from the group consisting of the component serving as the receiving layer of the first ink and the cationic resin contained in the reaction solution and the coloring material contained in the first ink (coloring material: from the group). At least one selected) is 1.96: 1 to 10: 1.
The content of at least one selected from the group consisting of the component serving as the receiving layer of the first ink and the cationic resin contained in the reaction solution is 0.1 to 6% by mass with respect to the total mass of the reaction solution. ,
Recording method. The first ink and the second ink contain a pigment as a coloring material.
The recording method according to claim 1. The ratio of the number of moles (unit: mol) of the aggregating agent contained in the reaction solution to the total mass (unit: g) of the coloring material contained in the first ink and the second ink (coloring material: agglomeration). Agent) is 100: 1 to 5000: 1.
The recording method according to claim 1 or 2. The flocculant comprises at least one selected from the group consisting of polyvalent metal salts and organic acids.
The recording method according to any one of claims 1 to 3. The ratio (coloring material) of the number of moles (unit: mol) of the polyvalent metal salt contained in the reaction solution to the total mass (unit: g) of the coloring material contained in the first ink and the second ink. : Polyvalent metal salt) is 1000: 1 to 31000: 1.
The recording method according to claim 4. The ratio of the number of moles (unit: mol) of the organic acid contained in the reaction solution to the total mass (unit: g) contained in the coloring materials of the first ink and the second ink (coloring material: organic acid). ) Is 800: 1 to 5500: 1.
The recording method according to claim 4 or 5. The content of the white color material is 3 to 15% by mass with respect to the total mass of the first ink.
The recording method according to any one of claims 1 to 6. The surface tension of the reaction solution is 55 mN / m or less at 25 ° C.
The recording method according to any one of claims 1 to 7. The recording method according to any one of claims 1 to 8, wherein the reaction solution contains anionic inorganic fine particles as a component to be a receiving layer of the first ink. At least one selected from the group consisting of the receiving layer component contained in the reaction solution and the cationic resin (unit: g), and the coloring material (unit: g) contained in the first ink. The mass ratio with and (color material: at least one selected from the group) is 7: 1 to 70: 1.
The recording method according to any one of claims 1 to 9. When the reaction solution contains a polyvalent metal salt as the flocculant, the content of the polyvalent metal salt is 0.5 to 5% by mass with respect to the total mass of the reaction solution, and when it contains an organic acid, it is organic. The acid content is 1-7% by weight based on the total mass of the reaction solution.
The recording method according to any one of claims 1 to 10. Volatilization of the volatile components contained in the reaction solution and the first ink on the non-absorbable recording medium or the low-absorbing recording medium after the first step and before the second step. The amount is 95% by mass or less with respect to 100% by mass of the total mass of the volatile components contained in the reaction solution and the first ink before application.
The recording method according to any one of claims 1 to 11. The number of moles (unit: mol) of the polyvalent metal salt contained in the reaction solution per unit area of the non-absorbable recording medium or the low-absorbing recording medium, and the first ink and the second ink. The ratio (color material: polyvalent metal salt) to the total mass (unit: g) of the color material contained in is 1000: 1 to 31000: 1.
The recording method according to any one of claims 1 to 12. The number of moles (unit: mol) of the organic acid contained in the reaction solution per unit area of the non-absorbable recording medium or the low-absorbing recording medium, and the first ink and the second ink. The ratio (coloring material: organic acid) to the total mass (unit: g) of the coloring material is 800: 1 to 5500: 1.
The recording method according to any one of claims 1 to 13. From the components of the reaction solution, which are the receiving layers of the first ink and the second ink, and the cationic resin per unit area of the non-absorbable recording medium or the low-absorbing recording medium. The ratio of the mass (unit: g) of at least one selected from the group to the mass (unit: g) of the coloring material contained in the first ink (coloring material: at least one selected from the group) is 7: 1 to 70: 1,
The recording method according to any one of claims 1 to 14.

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