JP2021066864A - Ink set, inkjet printing device, and inkjet printing method - Google Patents

Abstract

To provide an ink set that achieves excellent image quality even when color ink is printed on a white ink layer forming part just after printing and also achieves high white concealability.SOLUTION: An ink set contains a pre-processing fluid comprising a multivalent metal ion, a first ink and a second ink, wherein the first ink and the second ink each have a surface tension of 35 mN/m or greater at 25°C and a life time of 150 ms, and the second ink is a white ink.SELECTED DRAWING: Figure 1

Description

The present invention relates to ink sets, inkjet printing devices and inkjet printing methods.

Inkjet printers have advantages such as low noise, low running cost, and easy color printing, so they are widely used in general households as digital signal output devices.
In recent years, not only for household use, but also for slow-penetrating media such as coated paper, non-absorbent media such as plastic film, and fabrics such as woven fabrics and knitted fabrics, the image quality comparable to that of conventional analog printing has been achieved by the inkjet recording method. It is now required to acquire.
For example, in the so-called flexible packaging field, small lots and a wide variety of printing jobs are rapidly increasing, and demand for variable printing is also increasing. For example, inkjet-based, polyester-based, polyamide-based, etc. An inkjet recording system compatible with flexible packaging films is desired.

On the other hand, as in the flexible packaging field, in the printing field, the market size of the so-called DTG (Direct to Garment) field, which prints directly on clothing such as T-shirts, is expanding year by year, and the personal recommendation business in the apparel industry in recent years. Demand for inkjet recording systems that can form images with excellent color development and various robustness for fabrics is increasing due to trends such as the rise of the product and the active collaboration with fine art recognized in the field of interior textiles. It's on the way.
As inks for such fabrics, the development of water-based inks is most active from the viewpoint of low VOC and safety.

In the DTG field, conventionally, in dark-colored fabrics, it has been common to form a color ink layer on a white ink layer 30 seconds to 1 minute after forming a white ink layer. However, in recent years, due to the increasing demand for high productivity, technological development for shortening the time from the formation of the white ink layer to the formation of the color ink layer in the dark color fabric has been actively carried out.

For example, Patent Document 1 describes a printing inkjet ink containing a pigment, a water-dispersible resin, water, and a water-soluble organic solvent, wherein the water-dispersible resin has a film elongation of 400 to 1000% and a tensile strength of 20 to 20. An anionic resin having an absolute value of 50 N / mm 2 and a zeta potential (mV) of 40 or more; the content of the anionic resin is in the range of 0.5 to 2.5 with respect to pigment 1 by weight. Yes; and the surface tension of the ink is 30 to 50 mN / m. By using the ink for printing inkjet, the washing fastness and the friction fastness are good, and even when it is used for a dark-colored cloth or the like. It is said that good concealment can be achieved.

However, the method disclosed in Patent Document 1 achieves both excellent image quality and high white concealment even when color ink is printed on the white ink layer forming portion immediately after printing white ink. It couldn't be realized. That is, when the color ink is printed on the white ink layer in a short time without being dried after printing the white ink, the color ink bleeds, so that the image quality of the color printing portion and the excellent white hiding property are excellent. It was difficult to achieve both.

Therefore, an object of the present invention is to provide an ink set capable of achieving both excellent image quality and high white concealment even when color ink is printed on the white ink layer forming portion immediately after printing. There is.

The above problem is solved by the following configuration 1).
1) An ink set including a pretreatment liquid containing multivalent metal ions, a first ink, and a second ink.
The first ink and the second ink have a surface tension of 35 mN / m or more at 25 ° C. and a life time of 150 ms.
An ink set characterized in that the second ink is white ink.

According to the present invention, it is possible to provide an ink set capable of achieving both excellent image quality and high white concealment even when color ink is printed on a white ink layer forming portion immediately after printing. Can be done.

It is a perspective explanatory drawing which shows an example of an inkjet recording apparatus. It is a perspective explanatory view which shows an example of the main tank in an inkjet recording apparatus.

The present invention relates to the above 1), but also includes the following 2) to 9) as embodiments.
2) The ink set according to 1) above, wherein the surface tension of the first ink at 25 ° C. and a life time of 150 ms is equal to or higher than the surface tension of the second ink at 25 ° C. and a life time of 150 ms. ..
3) The ink set according to 1) or 2) above, wherein the difference in surface tension between the first ink and the second ink at 25 ° C. and a life time of 150 ms is 10 mN / m or less.
4) The above 1) to 3), wherein the difference in surface tension between the first ink and the second ink at 25 ° C. and a life time of 150 ms is 5 mN / m or less. Ink set.
5) The ink set according to any one of 1) to 4) above, wherein the pretreatment liquid contains 0.001% by mass or more and 1.000% by mass or less of a silicone-based surfactant.
6) The ink set according to any one of 1) to 5) above, wherein the surface tension of the second ink at 25 ° C. and a life time of 150 ms is 40 mN / m or more.
7) The ink set according to any one of 1) to 6) above, wherein the first ink contains a silicone-based surfactant.
8) In an inkjet printing apparatus having a means for applying a pretreatment liquid and an ejection means for ejecting ink, the inkjet printing apparatus has the ink set according to any one of 1) to 7) above. ..
9) In an inkjet printing method having a step of applying a pretreatment liquid and a step of ejecting ink, the step of applying the pretreatment liquid is to apply a pretreatment liquid containing polyvalent metal ions on a recording medium. The step of ejecting the ink is a step of ejecting the first ink and the second ink to the portion to which the pretreatment liquid is applied. An inkjet printing method in which the surface tension at 25 ° C. and a life time of 150 ms is 35 mN / m or more, and the second ink is white ink.

The ink set of the present invention includes a pretreatment liquid containing polyvalent metal ions, a first ink, and a second ink, and the first ink and the second ink have a life time of 150 ms at 25 ° C. The surface tension of the second ink is 35 mN / m or more, and the second ink is white ink.

(Pretreatment liquid)
The pretreatment liquid used in the present invention contains polyvalent metal ions.
The multivalent metal ion can be appropriately selected from known ones, and examples thereof include calcium ion, magnesium ion, and aluminum ion. These may be used alone or in combination of two or more.

The polyvalent metal ion can be contained in the pretreatment liquid by dissolving a water-soluble polyvalent metal salt.
The polyvalent metal salt can be appropriately selected from known ones, and for example, carboxylates (acetic acid, lactic acid, etc.), sulfates, nitrates, chlorides, and thiocyanates are suitable. The polyvalent metal salt may be used alone or in combination of two or more. Among these, carboxylates, sulfates, nitrates, and chlorides, which have good solubility in water and organic solvents, have white hiding properties and the viewpoint of image quality during color ink printing in a short time after printing with white ink. Is preferable.

The content of the multivalent metal ion in the pretreatment liquid is preferably 2 g / L or more and 40 g / L or less, more preferably 4 g / L or more and 30 g / L or less, from the viewpoint of white hiding property and suppression of bleeding. , 8 g / L or more and 20 g / L are more preferable.

The pretreatment liquid preferably contains a silicone-based surfactant from the viewpoint of white hiding property and image quality during color ink printing in a short time after printing with white ink.
The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose, but it is preferable to use a compound represented by the following general formula (2) from the viewpoint of white hiding property and suppression of bleeding.

In the general formula (2), R represents a hydrogen atom or a methyl group, m1 and m2 represent an integer of 0 to 6, and n represents an integer of 2 to 20.

R in the general formula (2) is preferably a hydrogen atom from the viewpoint of storage stability and uniformity, and R is preferably a methyl group from the viewpoint of suppressing bleeding, and both are used in combination. It is more preferable to do so.

Examples of the silicone-based surfactant include 71ADDITIVE, 74ADDITIVE, 57ADDITIVE, 8029ADDITIVE, 8054ADDITIVE, 8211ADDITIVE, 8019ADDITIVE, 8526ADDITIVE, FZ-2123, FZ-2191 (all manufactured by TORAY Dow Corning Co., Ltd. TSF4446, TSF4450, TSF4452, TSF4460 (all manufactured by Momentive Performance Materials); Silface SAG002, Silface SAG003, Silface SAG005, Silface SAG013, Silface SAG503A, Silface SAG008, Silface SJM003 (all are manufactured by Momentive Performance Materials). Nisshin Kagaku Kogyo Co., Ltd.); TEGO Wet KL245, TEGO Wet 240, TEGO Wet 250, TEGO Wet 260, TEGO Wet 265, TEGO Wet 270, TEGO Wet 280 (all manufactured by Ebonic); BYK-345, BYK- 347, BYK-348, BYK-349, BYK-375, BYK-377 (all manufactured by Big Chemie Japan Co., Ltd.) and the like can be mentioned.
Among these, examples of the silicone-based surfactant represented by the general formula (2) include BYK-345, 347, 348, 349 (all manufactured by Big Chemie Japan), TEGO Wet240, TEGO Wet270, and TEGO. Examples include Wet280 (all manufactured by Evonik Industries), Silface SAG002, Silface SAG013, and Silface SAG503A (all manufactured by Nisshin Kagaku Kogyo Co., Ltd.).

The content of the silicone-based surfactant in the pretreatment liquid is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of white hiding property and bleeding suppression, 0.001% by mass or more and 1.000% by mass. % Or less is preferable, 0.005% by mass or more and 0.500% by mass or less is more preferable, and 0.010% by mass or more and 0.200% by mass or less is more preferable.

The method for applying the pretreatment liquid is not particularly limited, and can be appropriately selected from known ones such as roller coating, dipping, spray coating, and inkjet coating, depending on the intended purpose.

^{The amount of the pretreatment liquid applied per unit area is 0.02 mg / cm 2} from the viewpoint of high white concealment and excellent image quality even when color ink is printed on the white ink layer forming portion immediately after printing. It is preferably 200 mg / cm ^{2 or more.} Furthermore, when applied in a spray or roller, more preferably 10 mg / cm ² or more 100 mg / cm ² or less, when the coating is ejected by an inkjet is 0.04 mg / cm ² or more 4.0 mg / cm ² It is more preferable that it is as follows.

The pretreatment liquid preferably contains a resin from the viewpoint of robustness. The resin can be appropriately selected from known ones, and is a nonionic resin such as polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, a urethane resin having a structural unit represented by the general formula (1), an acrylic resin, and the like. Polyester resin and the like are preferable.
− (CH ₂ CH ₂ O) n− General formula (1)
However, n is 5 or more and 100 or less.

The content of the resin in the pretreatment liquid is, for example, preferably 0.01 to 30% by mass, more preferably 0.1 to 15% by mass.

The pretreatment liquid may contain an organic solvent, an antifoaming agent, an antifungal agent, an anticorrosive agent, and the like, depending on the intended use. Details of these components will be described later.

In the present invention, the first ink and the second ink have a surface tension of 35 mN / m or more, more preferably 40 mN / m or more, still more preferably 45 mN / m or more at 25 ° C. and a life time of 150 ms. .. If the surface tension at 25 ° C. and a life time of 150 ms is less than 35 mN / m, bleeding of the color ink is likely to occur, and the image quality is deteriorated when the color ink is printed on the white ink layer forming portion immediately after printing. Further, when the surface tension of the second ink at a life time of 150 ms is 40 mN / m or more, the white hiding property is further improved.

As described above, the second ink is a white ink, and the first ink is a normal color ink.

Further, the first ink can be of a plurality of types including different coloring materials, and in this case, all the first inks have a surface tension of 35 mN / m or more at 25 ° C. and a life time of 150 ms. Is preferable.

In the present invention, it is preferable that the surface tension of the first ink at 25 ° C. and a life time of 150 ms is equal to or higher than the surface tension of the second ink at 25 ° C. and a life time of 150 ms. As a result, bleeding and feathering of the first ink are further suppressed.

Further, in the present invention, the difference in surface tension between the first ink and the second ink at 25 ° C. and a life time of 150 ms is preferably 10 mN / m or less. As a result, bleeding and feathering of the first ink are further suppressed. Further, when the difference is 5 mN / m or less, the bleeding / feathering of the first ink is further suppressed.

The pigment used in the second ink is not particularly limited and may be appropriately selected depending on the intended use, but titanium oxide is particularly preferable.

The pigment used in the first ink is not particularly limited and may be appropriately selected depending on the intended use. Details of these components will be described later.

The first ink preferably contains a silicone-based surfactant from the viewpoint of color development. As a result, the image quality (color development) is further improved.
The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose, but it is preferable to use a compound represented by the following general formula (2) from the viewpoint of color development.

In the general formula (2), R represents a hydrogen atom or a methyl group, m1 and m2 represent an integer of 0 to 6, and n represents an integer of 2 to 20.

R in the general formula (2) is preferably a hydrogen atom from the viewpoint of storage stability and uniformity, and R is preferably a methyl group from the viewpoint of suppressing bleeding, and both are used in combination. It is more preferable to do so.

Examples of the silicone-based surfactant include 71ADDITIVE, 74ADDITIVE, 57ADDITIVE, 8029ADDITIVE, 8054ADDITIVE, 8211ADDITIVE, 8019ADDITIVE, 8526ADDITIVE, FZ-2123, FZ-2191 (all manufactured by TORAY Dow Corning Co., Ltd. TSF4446, TSF4450, TSF4452, TSF4460 (all manufactured by Momentive Performance Materials); Silface SAG002, Silface SAG003, Silface SAG005, Silface SAG013, Silface SAG503A, Silface SAG008, Silface SJM003 (all are manufactured by Momentive Performance Materials). Nisshin Kagaku Kogyo Co., Ltd.); TEGO Wet KL245, TEGO Wet 240, TEGO Wet 250, TEGO Wet 260, TEGO Wet 265, TEGO Wet 270, TEGO Wet 280 (all manufactured by Ebonic); BYK-345, BYK- 347, BYK-348, BYK-349, BYK-375, BYK-377 (all manufactured by Big Chemie Japan Co., Ltd.) and the like can be mentioned.
Among these, examples of the silicone-based surfactant represented by the general formula (2) include BYK-345, 347, 348, 349 (all manufactured by Big Chemie Japan), TEGO Wet240, TEGO Wet270, and TEGO. Examples include Wet280 (all manufactured by Evonik Industries), Silface SAG002, Silface SAG013, and Silface SAG503A (all manufactured by Nisshin Kagaku Kogyo Co., Ltd.).

The content of the silicone-based surfactant in the first ink is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of color development, 0.01% by mass or more and 0.50% by mass or less is preferable. , 0.02% by mass or more and 0.30% by mass or less is more preferable.

In the present invention, the first ink and the second ink have a surface tension of 35 mN / m or more at 25 ° C. and a life time of 150 ms. Here, the surface tension means a dynamic surface tension. The dynamic surface tension can be controlled by the type and amount of the surfactant added.
The dynamic surface tension can be measured by a well-known and conventional method, but in the present invention, it is preferably measured by the maximum foam pressure method. A measuring instrument for dynamic surface tension by the maximum hydraulic pressure method is commercially available, and examples thereof include DynoTeter (manufactured by SITA).
The maximum foam pressure method is a method in which bubbles are discharged from the tip portion of a probe immersed in a liquid to be measured, and the surface tension is obtained from the maximum pressure required to release the bubbles.
When the radius of the bubble becomes equal to the radius of the probe tip, the maximum pressure is shown, and the dynamic surface tension σ of the ink at this time is expressed by the following equation.

σ = (ΔP · r) / 2
(Here, r is the radius of the probe tip, and ΔP is the difference between the maximum pressure applied to the bubble and the minimum value.)

Further, the life time referred to in the present invention means the time from when the bubbles are separated from the probe and a new surface is formed to the next maximum bubble pressure in the maximum bubble pressure method.

Next, the details of the pretreatment liquid, the first ink and the second ink (hereinafter, may be simply referred to as ink) in the present invention will be described.

<Ink>
Hereinafter, the organic solvent, water, coloring material, resin, additive, etc. used for the ink will be described.

<Organic solvent>
The organic solvent used in the present invention is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include ethers such as polyhydric alcohols, polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol , 2,4-Pentanediol, 1,5-Pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, Glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl- Polyhydric alcohols such as 1,3-pentanediol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl Polyhydric alcohol alkyl ethers such as ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone. , 1,3-Dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone and other nitrogen-containing heterocyclic compounds, formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, N- Amidos such as dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine and triethylamine, sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol, propylene carbonate and ethylene carbonate. And so on.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or lower because it not only functions as a wetting agent but also has good drying properties.

Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of the polyol compound 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 and ethylene glycol monobenzyl ether can be mentioned.

The content of the organic solvent in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 60% by mass or less from the viewpoint of ink drying property and ejection reliability. More preferably, it is 20% by mass or more and 60% by mass or less.

<Water>
The content of water in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of ink drying property and ejection reliability, it is preferably 10% by mass or more and 90% by mass or less, and 20% by mass. % To 60% by mass is more preferable.

<Color material>
The coloring material is not particularly limited, and pigments and dyes can be used.
As the pigment, an inorganic pigment or an organic pigment can be used. These may be used alone or in combination of two or more. Moreover, you may use a mixed crystal.
As the pigment, for example, a black pigment, a yellow pigment, a magenta pigment, a cyan pigment, a white pigment, a green pigment, an orange pigment, a glossy color pigment such as gold or silver, a metallic pigment, or the like can be used.
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, and thermal method. Can be used.
Examples of organic pigments include azo pigments and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.). , Dye chelate (for example, basic dye type chelate, acidic dye type chelate, etc.), nitro pigment, nitroso pigment, aniline black and the like can be used. Among these pigments, those having a good affinity with a solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
As a specific example of the pigment, for black, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron (CI pigment black 11) , Metals such as titanium oxide, and organic pigments such as aniline black (CI 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 (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 (Bengara), 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 Greens 1, 4, 7, 8, 10, 17, 18, 36, etc.
The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone or two or more types may be used in combination.
As the 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. Hood 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. Dilekdo Black 19,38,51,71,154,168,171,195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, 35 can be mentioned.

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

In order to disperse the pigment to obtain an ink, a method of introducing a hydrophilic functional group into the pigment to obtain a self-dispersing pigment, a method of coating the surface of the pigment with a resin and dispersing it, and a method of dispersing using a dispersant are used. The method, etc. can be mentioned.
As a method of introducing a hydrophilic functional group into a pigment to obtain a self-dispersing 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) so that the pigment can be dispersed in water. Can be mentioned.
Examples of the method of coating the surface of the pigment with a resin and dispersing the pigment include a method of encapsulating the pigment in microcapsules so that the pigment can be dispersed in water. This can be rephrased as a resin coating pigment. In this case, it is not necessary that all the pigments blended in the ink are coated with the resin, and the uncoated pigments and the partially coated pigments are 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 a high molecular weight dispersant represented by a surfactant.
As the dispersant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant and the like can be used depending on the pigment.
RT-100 (nonionic surfactant) manufactured by Takemoto Oil & Fat Co., Ltd. and a naphthalene sulfonate Na formalin condensate can also be suitably used as a dispersant.
One type of dispersant may be used alone, or two or more types may be used in combination.

<Pigment dispersion>
It is possible to obtain an ink by mixing a material such as water or an organic solvent with a pigment. It is also possible to produce an ink by mixing a material such as water or an organic solvent with a pigment dispersion obtained by mixing a pigment and other water or a dispersant.
The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. It is preferable to use a disperser for dispersion.
The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency is 20 nm or more in terms of the maximum number because the dispersion stability of the pigment is good and the image quality such as ejection stability and image density is also high. It is preferably 500 nm or less, more preferably 20 nm or more and 150 nm or less. The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good ejection stability and increasing the image density, 0.1 mass is used. % Or more and 50% by mass or less are preferable, and 0.1% by mass or more and 30% by mass or less are more preferable.
If necessary, the pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifuge, or the like.

<Resin>
The type of resin contained in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, etc. Examples thereof include resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, and acrylic silicone resins.
Resin particles made of these resins may be used. It is possible to obtain ink by mixing resin particles with a material such as a coloring material or an organic solvent in the state of a resin emulsion in which water is dispersed as a dispersion medium. As the resin particles, those synthesized as appropriate may be used, or commercially available products may be used. Further, these may be used alone or in combination of two or more kinds of resin particles.

The volume average particle diameter of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good fixability and high image hardness, 10 nm or more and 1,000 nm or less are preferable. More than 200 nm is more preferable, and 10 nm or more and 100 nm or less is particularly preferable.
The volume average particle size can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

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

The particle size of the solid content in the ink is not particularly limited and can be appropriately selected according to the purpose, but from the viewpoint of improving image quality such as ejection stability and image density, the maximum frequency in terms of the maximum number of inks. Is preferably 20 nm or more and 1000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solid content includes resin particles, pigment particles, and the like. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

<Additives>
If necessary, a surfactant, a defoaming agent, an antiseptic / antifungal agent, a rust preventive, a pH adjuster, or the like may be added to the ink.

<Surfactant>
As the surfactant, any of a silicone-based surfactant, a fluorine-based surfactant, an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant can be used.
The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose.
Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, single-ended modified polydimethylsiloxane, side chain double-ended modified polydimethylsiloxane, and the like. Those having an oxyethylene group and a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. Further, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include a compound in which a polyalkylene oxide structure is introduced into the Si portion side chain of dimethylsiloxane.
Examples of the fluorine-based surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. A polyoxyalkylene ether polymer compound is particularly preferable because it has a low foaming property. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonic acid salt. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salt. The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a perfluoroalkyl ether group in the side chain. Examples thereof include salts of polyoxyalkylene ether polymers. The counterions of the salts in these fluorine-based surfactants are Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH). ₃ etc. can be mentioned.
Examples of the amphoteric tenside agent include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, and lauryldihydroxyethylbetaine.
Examples of the nonionic surfactant include polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, and polyoxyethylene sorbitan. Examples thereof include a fatty acid ester and an ethylene oxide adduct of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, and polyoxyethylene alkyl ether sulfate salt.
These may be used alone or in combination of two or more.

As the fluorine-based surfactant, a compound having 2 to 16 carbon atoms substituted with fluorine is preferable, and a compound having 4 to 16 carbon atoms substituted with fluorine is more preferable.
Examples of the fluorine-based surfactant include a perfluoroalkyl phosphate compound, a perfluoroalkylethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is preferable because it has low foaming property, and is particularly a fluorine-based compound represented by the general formula (F-1) and the general formula (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.
General formula (F-2)
C _n F _{2n + 1-} CH ₂ CH (OH) CH ₂ −O− (CH ₂ CH ₂ O) _a− Y
In the compound represented by the above general formula (F-2), Y is H or CmF _{2m + 1} and m is an integer of 1 to 6, or CH ₂ CH (OH) CH _2- CmF _{2m + 1} and m is 4 to 6. It is an integer, or CpH _{2p + 1} and p is an integer of 1-19. n is an integer of 1-6. a is an integer of 4 to 14.
Commercially available products may be used as the above-mentioned fluorine-based surfactant. Examples of this commercially available product 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.); Full Lard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Co., Ltd.); Megafuck F-470, F -1405, F-474 (all manufactured by Dainippon Ink and Chemicals Co., Ltd.); 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 The Chemours Company); 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 Omniova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.) Among these, FS-3100, FS-34, FS- of The Chemours Co., Ltd., from the viewpoint of remarkably improving good print quality, particularly color development, penetrability to paper, wettability, and leveling property. 300, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omninova, and Unidyne DSN-manufactured by Daikin Industries, Ltd. 403N is particularly preferable.

The content of the surfactant in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of excellent wettability and ejection stability and improvement in image quality, 0.001 mass is used. % Or more and 5% by mass or less are preferable, and 0.05% by mass or more and 5% by mass or less are more preferable.

<Defoamer>
The defoaming agent is not particularly limited, and examples thereof include a silicone-based defoaming agent, a polyether-based defoaming agent, and a fatty acid ester-based defoaming agent. These may be used alone or in combination of two or more. Among these, a silicone-based defoaming agent is preferable because it has an excellent defoaming effect.

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

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

<pH adjuster>
The pH adjusting agent is not particularly limited as long as the pH can be adjusted to 7 or more, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical characteristics of the ink are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the viscosity, surface tension, pH and the like are preferably in the following ranges.
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, 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, for the viscosity, for example, a rotary viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used. As the measurement conditions, it is possible to measure at 25 ° C. with a standard cone rotor (1 ° 34'× R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN / m or less, more preferably 32 mN / m or less at 25 ° C. from the viewpoint that the ink is preferably leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably 7 to 12, more preferably 8 to 11, from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

<Post-treatment liquid>
The post-treatment liquid is not particularly limited as long as it is possible to form a transparent layer. The post-treatment liquid is obtained by selecting and mixing organic solvents, water, resins, surfactants, antifoaming agents, pH adjusters, antiseptic and antifungal agents, rust preventives and the like, if necessary. Further, the post-treatment liquid may be applied to the entire area of the recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

The recording medium is not limited to that used as a general recording medium, and wallpaper, floor materials, building materials such as tiles, cloth for clothing such as T-shirts, textiles, leather and the like can be appropriately used. Further, ceramics, glass, metal, or the like can be used by adjusting the configuration of the path for transporting the recording medium.

<Recorded material>
The ink recording material of the present invention comprises an image formed by using the ink of the present invention on a recording medium.
It can be recorded by an inkjet recording device and an inkjet recording method to obtain a recorded material.

The inkjet printing apparatus of the present invention includes means for applying a pretreatment liquid and ejection means for ejecting ink, and the inkjet printing apparatus has the ink set of the present invention.
Further, the inkjet printing method of the present invention includes a step of applying a pretreatment liquid and a step of ejecting ink, and the step of applying the pretreatment liquid applies the pretreatment liquid of the present invention on a recording medium. The step of ejecting the ink is a step of ejecting the first ink and the second ink in the present invention to the portion to which the pretreatment liquid is applied. For example, after ejecting the second ink (white ink), the first ink is preferably ejected at that location.

<Recording device, recording method>
The ink of the present invention can be suitably used for various recording devices by an inkjet recording method, for example, a printer, a facsimile device, a copying device, a printer / fax / copier multifunction device, a three-dimensional modeling device, and the like.
In the present invention, the recording device and the recording method are devices capable of ejecting ink, various processing liquids, and the like to a recording medium, and a method of recording using the device. The recording medium means a medium to which ink and various treatment liquids can adhere even temporarily.
This recording device can include not only a head portion for ejecting ink, but also means related to feeding, transporting, and discharging paper of a recording medium, and other devices called pretreatment devices and posttreatment devices. ..
The recording device and recording method may include a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, means for heating and drying the print surface and the back surface of the recording medium. The heating means and the drying means are not particularly limited, but for example, a hot air heater and an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like.
Further, the recording device and the recording method are not limited to those in which significant images such as characters and figures are visualized by ink. For example, those that form patterns such as geometric patterns and those that form a three-dimensional image are also included.
Further, the recording device includes both a serial type device that moves the discharge head and a line type device that does not move the discharge head, unless otherwise specified.
Further, as this recording device, it is possible to use not only a desktop type but also a wide recording device capable of printing on an A0 size recording medium, or, for example, continuous paper wound in a roll shape as a recording medium. A continuous line printer is also included.
An example of the recording device will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank. The image forming apparatus 400 as an example of the recording apparatus is a serial type image forming apparatus. A mechanical unit 420 is provided in 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 packaged with, for example, an aluminum laminate film. It is formed of members. The ink container 411 is housed in, for example, a plastic container case 414. As a result, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided behind 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 ejection port 413 of the main tank 410 and the ejection head 434 for each color communicate with each other via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 to the recording medium.

The method of using the ink is not limited to the inkjet recording method, and can be widely used. In addition to the inkjet recording method, examples thereof include a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method, and a spray coating method.

The use of the ink of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it can be applied to printed matter, paints, coating materials, base materials and the like. Further, 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 model).
A known three-dimensional modeling device can be used for modeling the three-dimensional object, and the device is not particularly limited, and for example, an device provided with ink accommodating means, supply means, ejection means, drying means, and the like is used. be able to. The three-dimensional model includes a three-dimensional model obtained by overcoating with ink. In addition, a molded product obtained by processing a structure in which ink is applied on a base material such as a recording medium is also included. The molded product is, for example, a recorded material or structure formed in a sheet shape or a film shape, which has been subjected to molding processing such as heat stretching or punching, and is, for example, an automobile, an OA equipment, or an electric machine. -Suitably used for molding after decorating the surface of electronic devices, meters of cameras, panels of operation parts, etc.

In addition, image formation, recording, printing, printing, etc. in the terms of the present invention are all synonymous.

Recording media, media, and printed matter are all synonymous.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Parts indicate mass parts.

(Preparation Example 1 of Pigment Dispersion)
<Preparation of black pigment dispersion>
After premixing the following formulation mixture, it is circulated and dispersed for 7 hours in a disc type bead mill (manufactured by Simmal Enterprises Co., Ltd., KDL type, media: using zirconia balls with a diameter of 0.3 mm) to obtain a black pigment dispersion (pigment concentration). : 15% by mass) was obtained.
-Carbon black pigment (trade name: Monarch800, manufactured by Cabot)
・ ・ ・ 15 parts ・ Anionic surfactant (trade name: Pionin A-51-B, manufactured by Takemoto Oil & Fats Co., Ltd.)
・ ・ ・ 2 parts ・ Ion-exchanged water ・ ・ ・ 83 parts

<Preparation of white pigment dispersion liquid 1>
Mix 40 parts of titanium oxide (trade name: JR-405, manufactured by Teika Co., Ltd.), 5 parts of pigment dispersant (trade name: TEGO Dispers 651, manufactured by Ebonic), 55 parts of water, and bead mill (trade name: Research Lab, Zirconia beads of 0.3 mmΦ were dispersed at a filling rate of 60% and 8 m / s for 5 minutes at Simmal Enterprises Co., Ltd. to obtain a white pigment dispersion liquid 1.
The volume average particle size D50 of the white pigment dispersion liquid 1 was measured using Nanotrack Nanotrac Wave-EX1500 (manufactured by Microtrac Bell Co., Ltd.) and found to be 210 nm.

[Manufacturing of resin particle dispersion]
The resin particle dispersion liquid 1 was synthesized by the following procedure. First, 31 parts of PEG-2000 (polyethylene glycol (manufactured by Sanyo Kasei, number average molecular weight 2000)) and T5651 (polycarbonate diol, manufactured by Asahi Kasei Chemicals) were placed in a 500 mL separable flask equipped with a stirrer, a thermometer, and a reflux tube. ) 73 parts, 32 parts of isophorone diisocyanate, and 90 parts of acetone dehydrated by a molecular sieve are charged, the temperature is raised to 70 ° C. under a nitrogen stream, 200 ppm of tin 2-ethylhexanoate is added, and the isocyanate concentration in the system is added. Was reacted at 70 ° C. for 3 to 10 hours while measuring. Next, the temperature in the system was lowered to 40 ° C., triethylamine was added as necessary, 270 parts of ion-exchanged water was added while stirring at a speed of 300 rpm, and after stirring for 1 hour, 2-methyl-1,5 was added. -4.5 parts of pentanediamine was added, and the mixture was stirred for 3 to 6 hours. Then, the mixture is cooled to room temperature, the solvent is distilled off with an evaporator, and the solid content is adjusted to 30% with ion-exchanged water to obtain a urethane resin particle dispersion having a structural unit represented by the general formula (1). I got 1.

The resin particle dispersion liquid 2 was synthesized by the following procedure. First, 52 parts of PCL 210 (polycaprolactone diol (manufactured by Daicel)), 7 parts of dimethylolpropionic acid, 30 parts of isophorone diisocyanate, and molecular as polyol in a 500 mL separable flask equipped with a stirrer, a thermometer, and a reflux tube. 90 parts of acetone dehydrated by a sieve was charged, the temperature was raised to 70 ° C. under a nitrogen stream, 200 ppm of tin 2-ethylhexanoate was added, and the isocyanate concentration in the system was measured for 3 hours at 70 ° C. It was allowed to react for 10 hours. Next, the temperature in the system was lowered to 40 ° C., triethylamine was added as necessary, 270 parts of ion-exchanged water was added while stirring at a speed of 300 rpm, and after stirring for 1 hour, 2 parts of diethylenetriamine was added and 3 Stir for hours to 6 hours. Then, the resin particle dispersion liquid 2 was obtained by cooling to room temperature, distilling off the solvent with an evaporator, and adjusting the solid content to 30% with ion-exchanged water.

The resin particle dispersion liquid 3 was synthesized by the following procedure. First, 70.0 parts of ion-exchanged water was placed in a 300 mL flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, and a reflux tube, the temperature was raised to 70 ° C. under a nitrogen stream, and the temperature was maintained for 2 hours. On the other hand, 21.6 parts of methyl methacrylate, 44 parts of 2-ethylhexyl acrylate, 7.6 parts of methoxypolyethylene glycol methacrylate (manufactured by Nichiyu, n = 23), 2.5 parts of vinyltriethoxysilane, and aqualon. 1.2 parts of HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 34.4 parts of ion-exchanged water were mixed to prepare an emulsified solution emulsified with a homomixer. Next, after adding 2.1 parts of a 10% aqualon HS-10 aqueous solution 3.0% and a 5% ammonium persulfate aqueous solution into the flask, the emulsion was continuously added dropwise over 2.5 hours. In addition, 0.4 part of a 5% ammonium persulfate aqueous solution was added every hour from the start of dropping until 3 hours had elapsed. After completion of the dropping, the mixture was aged at 70 ° C. for 2 hours, cooled to room temperature, adjusted to pH 7 to 8 with 28% aqueous ammonia and 30% solid content with ion-exchanged water to obtain a resin particle dispersion liquid 3.

The resin particle dispersion liquid 4 was synthesized by the following procedure. 60 parts of polycarbonate polyol (Duranol T5651, manufactured by Asahi Kasei Chemicals) with a number average molecular weight (Mn) of 1000 and 8 parts of dimethylol propionic acid in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube. , 48 parts of dicyclohexylmethane diisocyanate, and 112 parts of acetone dehydrated by a molecular sieve are added, the temperature is raised to 70 ° C. under a nitrogen stream, 200 ppm of tin 2-ethylhexanoate is added, and the isocyanate concentration in the system is measured. The reaction was carried out at 70 ° C. for 3 to 10 hours. Next, the temperature in the system was lowered to 40 ° C., triethylamine was added as necessary, 360 parts of ion-exchanged water was added while stirring at a speed of 300 rpm, and after stirring for 1 hour, 2 parts of diethylenetriamine was added and 3 Stir for hours to 6 hours. Then, the resin particle dispersion liquid 4 was obtained by cooling to room temperature, distilling off the solvent with an evaporator, and adjusting the solid content to 30% with ion-exchanged water.

(Example)
Preparation of Pretreatment Liquid and Ink The materials were mixed according to the formulations shown in Tables 1 to 3, stirred for 1 hour, and then pressure-filtered with a 1.2 μm cellulose acetate membrane filter to obtain a pretreatment liquid and ink. Ion-exchanged water was added so that the total amount was 100 parts.

As for the dynamic surface tension of the inks in the table, the dynamic surface tension at a surface life of 150 msec by the maximum foam pressure method was measured by SITA_DynoTester (manufactured by SITA) at 25 ° C. and 50% RH.

The materials in the table are as follows.
-SAG503A: Silicone surfactant represented by the general formula (2) (Silface SAG503A manufactured by Nisshin Kagaku Kogyo Co., Ltd.)
-BYK348: Silicone surfactant represented by the general formula (2) (BYK-348 manufactured by Big Chemie Japan)
・ Surfinol 465: Acetylene glycol-based surfactant (manufactured by Nisshin Kagaku Kogyo Co., Ltd.)

<Printing method 1>
A cotton T-shirt (white) manufactured by TOM'S was dried for 5 seconds by a heat press set at 160 ° C. Next, a pressed cotton T-shirt (white) manufactured by Tom's Co., Ltd. was set in Ri6000 (manufactured by Ricoh Co., Ltd.), and the inkjet printer was filled with white ink and Bk ink. Bk ink was printed with an adhesion amount of 2.0 mg / cm ² to form a 1 cm × 1 cm Bk solid image portion. This printing method 1 was applied to the following color development test.

<Printing method 2>
The pretreatment liquid was spray-applied to a cotton T-shirt (black) manufactured by TOM'S at a coating amount of 20 g / A4, and then dried by a heat press set at 160 ° C. for 1 minute.
Next, a cotton T-shirt (black) manufactured by Tom's Co., Ltd., which had been treated with a pretreatment liquid, was set in Ri6000 (manufactured by Ricoh Co., Ltd.), and the inkjet printer was filled with white ink and Bk ink. After a white ink was printed solid image adhered amount 20.0 mg / cm ² in 2 cm × 3 cm, the Bk ink deposition amount 2.0 mg / cm ² after the white ink printing starts after 5 seconds over the white ink layer A 1 cm × 1 cm Bk solid image portion was formed by printing on. This printing method 2 was applied to the following white concealment and bleeding tests.

<Color development>
A solid Bk image printed on a cotton T-shirt (white) manufactured by TOM'S was color-measured using X-rite exact to obtain an OD.
〔Evaluation criteria〕
A: OD is 1.30 or more
B: OD is 1.25 or more
C: OD is 1.20 or more
D: OD is less than 1.20 A to C pass.

<White concealment>
A solid image of only the white ink layer printed on a cotton T-shirt (black) manufactured by TOM'S was color-measured using X-rite exact, and the white hiding property was calculated by the following formula.
White concealment = (OD of original fabric-OD of solid image) / OD of original fabric x 100 (%)
〔Evaluation criteria〕
A: White concealment is 93% or more
B: White concealment is 88% or more and less than 93%
C: White hiding property is 85% or more and less than 88%
D: White concealment is 80% or more and less than 85%
E: White concealment is 70% or more and less than 80% A to C pass.

<Blur>
The boundary between the solid image portion of only the white ink layer and the Bk solid image portion on the white ink layer was evaluated by the following formula.
〔Evaluation criteria〕
A: No disturbance of the boundary is observed
B: There are 1 or 2 disturbances at the boundary.
C: Disturbances are observed in 3 to 4 places at the boundary
D: Disturbances are found in 5 or more places at the boundary. A to C are acceptable.

The results are shown in Tables 3 and 4.

From the results in Tables 3 and 4, each example passed the color development property, the white hiding property and the bleeding, but in the comparative example, both the white hiding property and the bleeding could reach the passing level. There wasn't.

400 Image forming device 401 Image forming device exterior 401c Device body cover 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For each color of black (K), cyan (C), magenta (M), yellow (Y) Main tank 411 Ink storage unit 413 Ink discharge port 414 Storage container case 420 Mechanical unit 434 Discharge head 436 Supply tube

Japanese Unexamined Patent Publication No. 2009-30014

Claims (9)

An ink set including a pretreatment liquid containing multivalent metal ions, a first ink, and a second ink.
The first ink and the second ink have a surface tension of 35 mN / m or more at 25 ° C. and a life time of 150 ms.
An ink set characterized in that the second ink is white ink. The ink set according to claim 1, wherein the surface tension of the first ink at 25 ° C. and a life time of 150 ms is equal to or higher than the surface tension of the second ink at 25 ° C. and a life time of 150 ms. The ink set according to claim 1 or 2, wherein the difference in surface tension between the first ink and the second ink at 25 ° C. and a life time of 150 ms is 10 mN / m or less. The ink set according to any one of claims 1 to 3, wherein the difference in surface tension between the first ink and the second ink at 25 ° C. and a life time of 150 ms is 5 mN / m or less. The ink set according to any one of claims 1 to 4, wherein the pretreatment liquid contains 0.001% by mass or more and 1.000% by mass or less of a silicone-based surfactant. The ink set according to any one of claims 1 to 5, wherein the surface tension of the second ink at 25 ° C. and a life time of 150 ms is 40 mN / m or more. The ink set according to any one of claims 1 to 6, wherein the first ink contains a silicone-based surfactant. In an inkjet printing apparatus having a means for applying a pretreatment liquid and an ejection means for ejecting ink, the inkjet printing apparatus is an inkjet printing apparatus having the ink set according to any one of claims 1 to 7. In an inkjet printing method having a step of applying a pretreatment liquid and a step of ejecting ink, the step of applying the pretreatment liquid is a step of applying a pretreatment liquid containing polyvalent metal ions on a recording medium. The step of ejecting the ink is a step of ejecting the first ink and the second ink to the portion to which the pretreatment liquid is applied, and the temperature of the first ink and the second ink is 25 ° C. An inkjet printing method in which the surface tension at a life time of 150 ms is 35 mN / m or more, and the second ink is white ink.

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