JP7019954B2 - Ink set, ink cartridge set, recording device, and recording method - Google Patents

Description

The present invention relates to an ink set, an ink cartridge set, a recording device, and a recording method.

Patent Document 1 uses an ink containing a pigment having a volume average particle size of 100 nm or more and 400 nm or less, and having a dynamic contact angle of 30 ° or more and 60 ° or less 50 seconds after dropping 3 μl on plain paper. When the ejection amount per drop is 1 ng or more and 2 ng or less, the ink droplets are ejected to the recording medium by the ejection head that ejects the ink droplets by heat, and the ink droplets adhere to the recording medium. Ink recording method for recording. ”Is disclosed.

Patent Document 2 states that "a recording paper having a basis weight of 60 to 75 g / m ² having a coating layer on at least the recording surface of the base material, and the coating layer contains a polyvinyl alcohol-based polymer as a binder. , Precipitated silica is contained as a fine particle filler, the density of the coating layer is 0.9 to 2.0 g / cm ³ , and the Clark rigidity (lateral direction) according to JIS P 8143 is 15 to 30 cm. An inkjet recording method for recording by applying ink to recording paper which is ^3/100 and has a dynamic contact angle of 5 to 30 degrees 1 second after dropping of non-aqueous ink. " ..

In Patent Document 3, "a recording head having a resolution of 1600 dpi or more, a number of nozzles of 1600 or more, and a heat generating resistor layer composed of a Ta layer is used, and the ink is directly applied to the ink from the heat generating resistor layer. An inkjet recording method in which heat energy is applied and the ink is ejected from the nozzle to record an image on a recording medium. The ink contains water, a water-soluble organic solvent, and a coloring material, and is described above. An inkjet recording method in which the dynamic contact angle with respect to the Ta layer as a heat generation resistor layer after 0.1 s is 20 to 40 degrees is disclosed.

Patent Document 4 states that "an ink containing at least water, a coloring material, an organic solvent and a vinyl polymer polymer having an acid value of 200 KOH mg / g or more, and the viscosity (V1) of the ink at 25 ° C. is 4 mPa · s <. An inkjet recording method using a water-based ink in which V1 <20 mPa · s and the value at 10 mS when the dynamic surface tension is measured at 25 ° C. is 35 mN / m or less is disclosed. "

Patent Document 5 states that "a pure water recording medium having a one-layer or multi-layer pigment layer on at least one surface of a support containing cellulose pulp as a main component and measured by a dynamic scanning liquid absorbent meter is used. At least one pigment as a coloring material on the recording medium having a transfer amount of 1 ml / m ² or more and 15 ml / m ² or less at a contact time of 100 ms and 2 ml / m ² or more and 20 ml / m ² or less at a contact time of 400 ms. An ink composition containing at least one resin particle, at least one water-soluble organic solvent, and water and having a surface tension of 30 mN / m or more and 40 mN / m or less is ejected by an inkjet method to record an image. An ink-ink recording method comprising at least an image recording step and a heating step of heating the recorded image. ”Is disclosed.

Japanese Unexamined Patent Publication No. 2012-096511 Japanese Unexamined Patent Publication No. 2011-205447 Japanese Unexamined Patent Publication No. 2005-205648 Japanese Unexamined Patent Publication No. 2014-224248 Japanese Unexamined Patent Publication No. 2011-042150

An object of the present invention is to provide a plurality of color water-based inks containing a colorant, polymer particles, water, and a water-soluble organic solvent, having a static surface tension of 30 mN / m or less and a dynamic surface tension of 34 mN / m or less. It is an ink set that has a dynamic contact angle of water-based ink after 2 msec, and is non-penetrating compared to an ink set in which the difference between the dynamic contact angles of water-based inks of multiple colors exceeds 2 °. It is an object of the present invention to provide an ink set for recording an image in which intercolor bleeding is suppressed for a recording medium.

The above problem is solved by the following means.

< 1 >
It has multiple color water-based inks that contain colorants , polymer particles, water, and water-soluble organic solvents and are different in color from each other.
The static surface tensions of the water-based inks of the plurality of colors are 30 mN / m or less, respectively.
When the dynamic surface tension was measured by the maximum foam pressure method, it was the dynamic surface tension of the water-based ink after 5 msec, and the dynamic surface tension of the water-based inks of the plurality of colors was 34 mN / m or less, respectively.
When 2 μl of water-based ink is dropped on a recording medium having a transfer amount of pure water to a recording medium of 3 to 15 ml / m ² at a contact time of 100 msec measured by a dynamic scanning liquid absorber, the dynamic of the water-based ink after 2 msec. An ink set having a contact angle in which the difference between the dynamic contact angles of the water-based inks of a plurality of colors is within 2 °.

< 2 >
When 2 μl of water-based ink is dropped on a recording medium having a transfer amount of pure water to a recording medium of 3 to 15 ml / m ² at a contact time of 100 msec measured by a dynamic scanning liquid absorber, the dynamic of the water-based ink after 2 msec. The ink set according to < 1 > , which has a contact angle and a dynamic contact angle of each of the plurality of colors of water-based ink is 54 ° or less.

< 3 >
When 2 μl of water-based ink is dropped on a recording medium having a transfer amount of pure water to a recording medium of 3 to 15 ml / m ² at a contact time of 100 msec measured by a dynamic scanning liquid absorber, the dynamic of the water-based ink after 1 sec. The ink set according to < 1 > or < 2 > , which is a contact angle and the dynamic contact angles of the water-based inks of the plurality of colors are 14 ° or more, respectively.

< 4 >
The ink set according to any one of < 1 > to < 3 > , wherein the difference between the dynamic surface tensions of the water-based inks of a plurality of colors is within 3 mN / m.

< 5 >
The ink set according to any one of < 1 > to < 4 > , wherein the static surface tensions of the water-based inks of the plurality of colors are 25 mN / m or more, respectively.

< 6 >
An ink cartridge set that houses each water-based ink of the ink set according to any one of < 1 > to < 5 > .

< 7 >
An ejection head that accommodates each water-based ink of the ink set according to any one of < 1 > to < 5 > and ejects each of the water-based inks onto a non-permeable recording medium.
A drying device for drying each of the water-based inks ejected onto the impermeable recording medium, and a drying device.
A recording device equipped with.

< 8 >
The ejection process of ejecting each water-based ink of the ink set according to any one of < 1 > to < 5 > onto a non-permeable recording medium, and
A drying step of drying each of the water-based inks ejected onto the impermeable recording medium, and
Recording method having.

According to the invention according to < 1 > , a plurality of colors containing a colorant, polymer particles, water, and a water-soluble organic solvent, having a static surface tension of 30 mN / m or less and a dynamic surface tension of 34 mN / m or less. Compared to ink sets that have water-based inks and the difference in "dynamic contact angle after 2 msec" of multiple colors of water-based inks exceeds 2 °, for non-permeable recording media. , An ink set that realizes image recording with suppressed intercolor blurring is provided.
According to the invention according to < 2 > , intercolor bleeding was suppressed for a non-permeable recording medium as compared with the case where the "dynamic contact angle after 2 msec" of the water-based inks of a plurality of colors exceeded 54 °. An ink set that realizes image recording is provided.
According to the invention according to < 3 > , the ejection failure of the water-based ink that occurs when continuously recording is suppressed as compared with the case where the "dynamic contact angle after 1 sec" of the water-based inks of a plurality of colors is less than 14 °. An ink set is provided.
According to the invention according to < 4 > , intercolor bleeding is suppressed for a non-permeable recording medium as compared with the case where the difference between the dynamic surface tensions of the water-based inks of a plurality of colors exceeds 3 mN / m. An ink set that realizes the recording of the image is provided.
According to the invention according to < 5 > , there is an ink set that suppresses ejection defects of the water-based ink that occurs when continuously recording, as compared with the case where the static surface tension of the water-based inks of a plurality of colors is less than 25 mN / m. Provided.
According to the invention according to < 6 > , < 7 > , or < 8 > , it contains a colorant, polymer particles, water, and a water-soluble organic solvent, and has a static surface tension of 30 mN / m or less and a dynamic surface tension. An ink set having a plurality of colors of water-based ink having a value of 34 mN / m or less, which is a dynamic contact angle of the water-based ink after 2 msec, and the difference between the dynamic contact angles of the water-based inks of a plurality of colors is 2 An ink cartridge set, a recording device, or a recording method that realizes recording of an image in which intercolor bleeding is suppressed is provided for an impermeable recording medium as compared with the case where an ink set exceeding ° is applied.

It is a schematic block diagram which shows the recording apparatus which concerns on this embodiment.

Hereinafter, embodiments that are an example of the present invention will be described in detail.

<Ink set>
The ink set according to the present embodiment includes a colorant, polymer particles, water, and an aqueous organic solvent, and has a plurality of colors of aqueous ink having different colors from each other. Hereinafter, "water-based ink" is also referred to as "ink".
Each of the water-based inks of a plurality of colors has a static surface tension of 30 mN / m or less, and when the dynamic surface tension is measured by the maximum foam pressure method, the dynamic surface tension after 5 msec is 34 mN / m or less.
Then, when 2 μl of the water-based ink was dropped onto the recording medium having a transfer amount of pure water to the recording medium at a contact time of 100 msec measured by a dynamic scanning liquid absorbent meter of 3 to 15 ml / m ² , the water-based ink after 2 msec was dropped. It is a dynamic contact angle, and the difference between the dynamic contact angles of the water-based inks of a plurality of colors is within 2 °.

Here, when ink is ejected to a non-penetrating recording medium, the ink that has landed on the recording medium does not penetrate or is difficult to penetrate into the recording medium, so that the ink droplets are high on the surface of the recording medium even when the ink droplets land. It remains with the ink. Therefore, the ink is difficult to dry on the non-permeable recording medium, and the fixability of the colorant is lowered. In particular, when an image is recorded with inks of a plurality of colors, the inks are difficult to dry and the fixability of the colorant is lowered. Therefore, as a characteristic of each ink of a plurality of colors, an ink having a characteristic of being easily dried quickly on a non-permeable recording medium and having high fixability has been studied.

One of them is a method of blending polymer particles in the ink to improve the fixability of the colorant, and reducing the static surface tension and the dynamic surface tension of the ink to make it easier for the ink to wet and spread on the recording medium. A method for increasing the drying efficiency of ink is known.

However, when the wettability and spreadability of the ink increases, intercolor bleeding may occur. This is a phenomenon in which when the ink droplets that landed first and spread wet on the recording medium are adjacent to the ink droplets that landed first and spread wet, they are attracted to the ink that landed first and spread wet and spread, and are mixed with each other. Is thought to occur. When this phenomenon occurs, it is considered that the ink is wetted and spreads away from the landing position of the subsequent ink droplets, and intercolor bleeding occurs.

Therefore, in the ink set according to the present embodiment, the static surface tension and the dynamic surface tension of each of the inks of a plurality of colors are set in the above range, and the dynamic contact angle of the inks of the plurality of colors (dynamic contact after 2 msec) is set. The difference between the corners) is also within the above range.

An ink having a static surface tension and a dynamic surface tension in the above range has a small static surface tension and a dynamic surface tension, and exhibits an ink having a property of rapidly wetting and spreading on a non-permeable recording medium. Since this ink quickly wets and spreads on a non-permeable recording medium, quick drying is realized even when the ink does not penetrate or is difficult to penetrate into the recording medium. Moreover, since it contains polymer particles, the fixing property of the colorant is also high.

Then, if the difference between the dynamic contact angles of the inks of multiple colors (dynamic contact angles after 2 msec) is reduced within the above range, the ink droplets that first land on the recording medium and spread wet are adjacent to each other. Then, when the ink droplets that landed later wet and spread, it becomes difficult to be attracted to the ink that landed first and spread wet. And it becomes difficult to mix with each other. It is considered that this is because when the dynamic contact angles of the ink that landed first and the ink that landed later are close, the force of coalescence weakens even if they come into contact with each other. As a result, it is considered that the subsequent ink droplets stay at the landing position and easily get wet and spread.

From the above, it is presumed that the ink set according to the present embodiment suppresses intercolor bleeding.
Further, in the ink set according to the present embodiment, it is presumed that the subsequent ink droplets stay at the landing position and wet and spread easily, so that image omission is suppressed and the graininess of the image is enhanced.

Examples of the non-permeable recording medium include coated paper and resin film. Specifically, the non-permeable recording medium is a recording medium in which ink does not permeate or does not easily permeate, and the maximum amount of pure water absorbed within a contact time of 500 msec measured by a dynamic scanning liquid absorbent meter is It means a recording medium having a temperature of 15 ml / m ² or less.

In the ink set according to the present embodiment, the static surface tension of each ink is 30 mN / m or less, preferably 28 mN / m or less. On the other hand, the static surface tension of each ink is preferably 21 mN / m or more, more preferably 25 mN / m or more, from the viewpoint of suppressing ink ejection defects that occur when continuously recording (from the viewpoint of ejection stability). ..

Here, the static surface tension of the ink is a value measured in an environment of 23 ° C. and 55% RH using a Wilhelmy type surface tension meter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.).

The dynamic surface tension of each ink is 34 mN / m or less, preferably 32 mN / m or less. On the other hand, the dynamic surface tension of each ink is preferably 24 mN / m or more, more preferably 30 mN / m or more, from the viewpoint of suppressing ink ejection defects that occur when continuously recording (from the viewpoint of ejection stability). ..

The difference in the dynamic surface tension of each ink is preferably within 3 mN / m, more preferably within 2 mN / m, from the viewpoint of intercolor bleeding and graininess. The difference between the dynamic surface tensions of each ink is most preferably 0 mN / m (that is, it is most preferable that there is no difference). The difference in the fluctuation range of the dynamic surface tension is an absolute value.

Here, the dynamic surface tension of the ink is the dynamic surface tension of the ink after 5 msec when the dynamic surface tension is measured by the maximum foam pressure method. Specifically, the dynamic surface tension of the ink is a value measured in an environment of 23 ° C. and 55% RH using a maximum foam pressure method dynamic surface tension meter MPTC (manufactured by LAUDA).
The value of the dynamic surface tension of the ink after 5 msec is the value of the dynamic surface tension when the maximum bubble pressure is reached in 5 msec after the new interface is formed at the tip of the capillary.

The difference between the "dynamic contact angles after 2 msec" of each ink is within 2 °, and more preferably within 1.5 ° from the viewpoint of intercolor bleeding and graininess. The difference between the "dynamic contact angles after 2 msec" of each ink is most preferably 0 ° (that is, it is most preferable that there is no difference). The difference in the dynamic contact angle is an absolute value.

The "dynamic contact angle after 2 msec" of each ink is preferably 54 ° or less, more preferably 52 ° or less, from the viewpoint of intercolor bleeding and graininess. On the other hand, the "dynamic contact angle after 2 msec" of each ink is preferably 48 ° or more, preferably 50 ° or more, from the viewpoint of suppressing ink ejection defects that occur during continuous recording (from the viewpoint of ejection stability). More preferred.

The "dynamic contact angle after 1 sec" of each ink is preferably 21 ° or less, more preferably 20 ° or less, from the viewpoint of intercolor bleeding and graininess. On the other hand, the "dynamic contact angle after 1 sec" of each ink is preferably 14 ° or more, preferably 15 ° or more, from the viewpoint of suppressing ink ejection defects that occur when continuously recording (from the viewpoint of ejection stability). Is more preferable.

Here, the "dynamic contact angle after 2 msec" of the ink is set to a recording medium in which the amount of pure water transferred to the recording medium at a contact time of 100 msec measured by a dynamic scanning liquid absorber is 3 to 15 ml / m ² . This is the dynamic contact angle after 2 msec when 2 μl of the water-based ink is dropped.
On the other hand, the "dynamic contact angle after 1 sec" of the ink is water-based in the recording medium in which the transfer amount of pure water to the recording medium at the contact time of 100 msec measured by the dynamic scanning liquid absorber is 3 to 15 ml / m ² . This is the dynamic contact angle after 1 sec when 2 μl of ink is dropped.

The "dynamic contact angle after 2 msec" and "dynamic contact angle after 1 sec" of the ink were measured in an environment of 23 ° C. and 55% RH using a dynamic contact angle tester 1100DAT (manufactured by Fibro System AB). It is the value that was set.
The "dynamic contact angle after 2 msec" and "dynamic contact angle after 1 sec" of the ink are calculated as follows. First, 2 μl of ink is dropped on the recording medium, and the ink droplets are imaged when 2 msec or 1 sec has elapsed from the time when the ink droplets come into contact with the recording medium. Then, from the captured image, the diameter of the surface where the ink droplets are in contact with the recording medium and the height of the ink droplets are analyzed, the forward contact angle is obtained, and this forward contact angle is used as each dynamic contact angle.

On the other hand, the amount of pure water transferred to the recording medium at a contact time of 100 msec was measured in an environment of 23 ° C. and 55% RH using a dynamic scanning liquid absorption meter (DSA) manufactured by Kyowa Seiko Co., Ltd. The value.

Here, as a method of adjusting the static surface tension and the dynamic surface tension in the above range in each ink, for example, a method of adjusting with a surfactant (type and amount thereof) can be mentioned.
For example, as a surfactant, the desired static surface tension can be obtained by combining the amount of the surfactant having an HLB (hydrophilic group / hydrophobic group balance “Hydrophile-Lipophile Balance”) of 14 or less. Further, among the surfactants having an HLB of 14 or less, it is possible to adjust to the dynamic surface tension by using a plurality of types of surfactants having different HLBs. Specifically, for example, by mixing a surfactant having an HLB of 11 or more and 14 or less and a surfactant having an HLB of 4 or more and less than 11, the desired dynamic surface tension can be obtained.
By way of example, increasing the amount of Orphine E1004 (HLB = 7-9) tends to reduce the static surface tension. Also, along with Orfin E1004 (HLB = 7-9), Orfin E1010 (HLB = 13-14) and EXP. When used in combination with at least one of 4123 (HLB = 11-14), the compatibility of Orfin E1004 (HLB = 7-9) tends to increase and the dynamic surface tension tends to decrease.

Further, as a method for adjusting the dynamic contact angle within the above range in each ink, for example, in addition to the surfactant (type and amount thereof), the amount of solid content and dispersibility (mainly the amount of polymer particles and the amount) Dispersibility) can be mentioned.
For example, the dynamic contact angle can be adjusted by adding an amount of a surfactant containing polyether-modified silicone as a main component. By way of example, when the amount of SAG002 (HLB = 12) added is reduced, the dynamic contact angle tends to increase.
At the same time, as the amount of solids in the ink increases, the dynamic contact angle tends to increase. When the dispersibility of the solid content in the ink is low, the dynamic contact angle tends to be high.
Furthermore, increasing the rate of increase in viscosity of the ink during evaporation tends to increase the dynamic contact angle. To increase the viscosity increase rate of the ink, for example, 1) a method using a moisturizing solvent such as glycerin, 2) a method of adjusting the amount of solid components added such as polymer particles, and 3) adjusting the molecular weight of the polymer. There are methods and so on.

Here, in the ink set according to the present embodiment, the plurality of color inks are, for example, black ink, cyan ink, magenta ink, yellow ink, and at least two kinds of plurality of colors selected from intermediate color inks other than these colors. Consists of ink. The ink set includes black ink, inks of a plurality of colors other than black (for example, cyan ink, magenta ink, and yellow ink, and inks of at least two kinds of multiple colors selected from intermediate color inks other than these colors). ), And preferably composed of black ink and three color inks of cyan ink, magenta ink, and yellow ink.

Next, the composition and characteristics of each ink in the ink set according to the present embodiment will be described in detail.

Each ink in the ink set according to the present embodiment contains colorants having different colors from each other. In addition to the colorant, each ink contains polymer particles, water, and an aqueous organic solvent.

(Colorant)
Next, the colorant will be described.
As the colorant, an agent corresponding to the water-based ink having a target hue may be used, and specific examples thereof include pigments. Examples of the pigment include organic pigments and inorganic pigments.

Specific examples of the black pigment (black pigment) include Raven7000, Raven5750, Raven5250, Raven5000 ULTRAII, Raven3500, Raven2000, Raven1500, Raven1250, Raven1200, Raven1190, Raven1190, Raven1190, Raven1190, Raven1190, Raven1 ) Regal400R, Regal330R, Regal660R, Mogul L, Black Pearls L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1300, Monarch 1300, FW2, Color Black FW2V, Color Black 18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex35, PrintEx U, PrintEx Special Black4 (all manufactured by Orion Engineered Carbons), No. 25, No. 33, No. 40, No. 47, No. 52, No. 900, No. 2300, MCF-88, MA600, MA7, MA8, MA100 (all manufactured by Mitsubishi Chemical Corporation) and the like can be mentioned, but the present invention is not limited thereto.

Specific examples of the cyan pigment include C.I. I. Pigment Blue-1, -2, -3, -15, -15: 1, -15: 2, -15: 3, -15: 4, -16, -22, -60 and the like. Not limited.
Specific examples of magenta color pigments include C.I. I. Pigment Red-5, -7, -12, -48, -48: 1, -57, -112, -122, -123, -146, 168, -177, -184, -202, C.I. I. Pigment Violet-19 and the like, but are not limited thereto.
Specific examples of the yellow pigment include C.I. I. Pigment Yellow-1, -2, -3, -12, -13, -14, -16, -17, -73, -74, -75, -83, -93, -95, -97, -98, Examples thereof include, but are not limited to, -114, -128, -129, -138, -151, -154, and -180.

Here, when a pigment is used as the colorant, it is preferable to use a pigment dispersant together. Examples of the pigment dispersant used include polymer dispersants, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants and the like.

As the polymer dispersant, a polymer having a hydrophilic structure portion and a hydrophobic structure portion is preferably used. As the polymer having a hydrophilic structure portion and a hydrophobic structure portion, for example, a condensation polymer and an addition polymer are used. Examples of the condensation-based polymer include known polyester-based dispersants. Examples of the addition polymer include a monomer addition polymer having an α, β-ethylenically unsaturated group. The desired high level is achieved by combining and copolymerizing a monomer having an α, β-ethylenically unsaturated group having a hydrophilic group and a monomer having an α, β-ethylenically unsaturated group having a hydrophobic group. A molecular dispersant is obtained. Further, a homopolymer of a monomer having an α, β-ethylenically unsaturated group having a hydrophilic group is also used.

Examples of the monomer having an α, β-ethylenic unsaturated group having a hydrophilic group include a monomer having a carboxyl group, a sulfonic acid group, a hydroxyl group, a phosphoric acid group and the like, for example, acrylic acid, methacrylic acid and croton. Acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bis Examples thereof include methacryloxyethyl phosphate, methacrylooxyethylphenyl acid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate and the like.

Examples of the monomer having an α, β-ethylenically unsaturated group having a hydrophobic group include styrene derivatives such as styrene, α-methylstyrene and vinyltoluene, vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives and acrylic acid alkyl esters. , Methacrylic acid alkyl ester, methacrylic acid phenyl ester, methacrylic acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl ester, maleic acid dialkyl ester and the like.

Examples of preferred copolymers as polymer dispersants include styrene-styrene sulfonic acid copolymers, styrene-maleic acid copolymers, styrene-methacrylic acid copolymers, styrene-acrylic acid copolymers, and vinylnaphthalene-. Maleic acid copolymer, vinyl naphthalene-methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, acrylic acid alkyl ester-acrylic acid copolymer, methacrylic acid alkyl ester-methacrylic acid copolymer, styrene-methacrylic acid Alkyl ester-methacrylic acid copolymer, styrene-acrylic acid alkyl ester-acrylic acid copolymer, styrene-methacrylic acid phenyl ester-methacrylic acid copolymer, styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer, or these. Examples include the salt of the polymer. Further, these polymers may be copolymerized with a monomer having a polyoxyethylene group and a hydroxyl group.

The weight average molecular weight of the polymer dispersant is, for example, 2,000 or more and 50,000 or less.

These polymer dispersants may be used alone or in combination of two or more. The content of the polymer dispersant varies greatly depending on the pigment and cannot be unequivocally determined, but it is preferably 0.1% by mass or more and 100% by mass or less with respect to the pigment.

Examples of the pigment include a pigment that self-disperses in water (hereinafter referred to as a self-dispersion type pigment).
The self-dispersing pigment refers to a pigment that has a solubilizing group for water on the surface of the pigment and is dispersed in water even in the absence of a polymer dispersant. The self-dispersion pigment can be obtained, for example, by subjecting the pigment to surface modification treatments such as acid / base treatment, coupling agent treatment, polymer graft treatment, plasma treatment, and oxidation / reduction treatment.

As the self-dispersion type pigment, in addition to the pigment obtained by subjecting the above pigment to a surface modification treatment, Cab-o-jet-200, Cab-o-jet-300, and Cab-o-jet-400 manufactured by Cabot Co., Ltd. , IJX-157, IJX-253, IJX-266, IJX-273, IJX-444, IJX-55, Cab-o-jet-250C, Cab-o-jet-260M, Cab-o-jet-270Y, Cab -O-jet-450C, Cab-o-jet-465M, Cab-o-jet-470Y, Cab-o-jet-480M, Microjet Black CW-1, CW-2, etc. manufactured by Orient Chemical Co., Ltd. Dispersed pigments and the like can also be mentioned.

The self-dispersion pigment is preferably a pigment having at least a sulfonic acid, a sulfonic acid salt, a carboxylic acid, or a carboxylic acid salt as a functional group on the surface thereof. More preferably, it is a pigment having at least a carboxylic acid or a carboxylic acid salt as a functional group on the surface.

Here, examples of the pigment include pigments coated with a resin. This is called a microcapsule pigment, and there are commercially available microcapsule pigments manufactured by DIC Corporation, Toyo Ink Corporation, and the like. The microcapsule pigment is not limited to the commercially available microcapsule pigment, and a microcapsule pigment produced according to the purpose may be used.
Further, examples of the pigment include a resin-dispersed pigment in which a polymer compound is physically adsorbed or chemically bonded to the pigment.
In addition to the three primary color pigments of black, cyan, magenta, and yellow, specific color pigments such as red, green, blue, brown, and white, metallic glossy pigments such as gold and silver, and colorless or light-colored constitutions are used as pigments. Pigments, plastic pigments and the like can also be mentioned.
Further, examples of the pigment include particles having silica, alumina, or a polymer bead as a core and a dye or pigment adhered to the surface thereof, an insoluble rake of the dye, a colored emulsion, a colored latex, and the like.

Coloring agents include, in addition to pigments, hydrophilic anionic dyes, direct dyes, cationic dyes, reactive dyes, polymer dyes and other dyes such as oil-soluble dyes, dye-colored wax powders and resin powders. Alternatively, emulsions, fluorescent dyes, fluorescent pigments and the like can also be mentioned.

The volume average particle size of the colorant is, for example, 10 nm or more and 1000 nm or less.
The volume average particle size of the colorant means the particle size of the colorant itself or, when an additive such as a dispersant is attached to the colorant, the particle size to which the additive is attached.
The volume average particle size is measured by the Microtrac UPA particle size analyzer UPA-UT151 (manufactured by Microtrac). The measurement is performed by putting a 1000-fold diluted water-based ink into a measurement cell. As the input value at the time of measurement, the viscosity of the aqueous ink diluent is used as the viscosity, and the refractive index of the colorant is used as the refractive index of the particles.

The content (concentration) of the colorant is, for example, preferably 1% by mass or more and 25% by mass or less, and more preferably 2% by mass or more and 20% by mass or less with respect to the water-based ink.

(Polymer particles)
The polymer particles will be described.
The polymer particles are components that enhance the fixing property of an image by a water-based ink on a recording medium.
The polymer particles are obtained by granulating a polymer compound and are different components from the above-mentioned polymer dispersant.

As the polymer particles, polymer particles having a glass transition temperature Tg of 35 ° C. or higher and 65 ° C. or lower are applied. When the glass transition temperature Tg of the polymer particles is set in the above range, the generation of latency is suppressed and the fixability of the water-based ink is easily improved (that is, the scratch resistance of the image is improved).
The glass transition temperature of the polymer particles is obtained from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, in the method of obtaining the glass transition temperature of JIS K7121-1987 "Method for measuring the transition temperature of plastics". It is determined by the described "external glass transition start temperature".

Examples of the polymer particles include styrene-acrylic acid copolymer, styrene-acrylic acid-sodium acrylate copolymer, styrene-butadiene copolymer, polystyrene, acrylonitrile-butadiene copolymer, and acrylic acid ester copolymer. , Polyurethane, polyester, silicon-acrylic acid copolymer, acrylic modified fluororesin and other particles (latex particles).
Examples of the polymer particles include core-shell type polymer particles having different compositions at the central portion and the outer edge portion of the particles.

The polymer particles may be dispersed in the water-based ink using an emulsifier, or may be dispersed in the water-based ink without using an emulsifier.
The emulsifier has a polymer having a hydrophilic group such as a surfactant, a sulfonic acid group, and a carboxyl group (for example, a polymer having a hydrophilic group graft-bonded, a monomer having hydrophilicity, and a hydrophobic portion. Polymers obtained from monomers).

The volume average particle size of the polymer particles is preferably 10 nm or more and 300 nm or less, more preferably 10 nm or more and 200 nm or less, from the viewpoint of glossiness and scratch resistance of the image.
The volume average particle size of the polymer particles is measured by the Microtrac UPA particle size analyzer UPA-UT151 (manufactured by Microtrac). The measurement is performed by putting a 1000-fold diluted water-based ink into a measurement cell. As the input value at the time of measurement, the viscosity of the aqueous ink diluent is adopted as the viscosity, and the refractive index of the polymer particles is adopted as the refractive index of the particles.

The content of the polymer particles is preferably 0.1% by mass or more and 10% by mass or less, preferably 0.5% by mass, with respect to the water-based ink from the viewpoint of enhancing the fixability of the image, ejection stability, and film forming property. More preferably, it is 5% by mass or less.

(water)
Explain water.
Preferred examples of the water include ion-exchanged water, ultrapure water, distilled water, and ultra-filtered water from the viewpoint of preventing the contamination of impurities or the generation of microorganisms.

The water content is, for example, preferably 10% by mass or more and 95% by mass or less, and more preferably 30% by mass or more and 90% by mass or less with respect to the water-based ink.

(Aqueous organic solvent)
The aqueous organic solvent will be described.
Examples of the aqueous organic solvent include polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, sulfur-containing solvents and the like. Examples of the aqueous organic solvent include propylene carbonate, ethylene carbonate and the like.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2-hexanediol, 1,2,6-hexanetriol, glycerin and the like. ..

Examples of the polyhydric alcohol derivative include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and diglycerin. Examples include ethylene oxide adducts.

Examples of the nitrogen-containing solvent include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, triethanolamine and the like.
Examples of the alcohol include ethanol, isopropyl alcohol, butyl alcohol, benzyl alcohol and the like.
Examples of the sulfur-containing solvent include thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide and the like.

The aqueous organic solvent may be used alone or in combination of two or more.

The content of the aqueous organic solvent is preferably 1% by mass or more and 60% by mass or less, and more preferably 1% by mass or more and 40% by mass or less with respect to water.

(Surfactant)
The surfactant will be described.
The water-based ink preferably contains, for example, a surfactant having an HLB (hydrophilic / hydrophobic group balance "Hydrophile-Lipophile Barance") of 14 or less as a surfactant. As described above, by adjusting the amount of the surfactant having an HLB of 14 or less, or by using a plurality of different HLB surfactants, the static surface tension and the dynamic surface tension of the water-based ink can be adjusted. And the dynamic contact angle can be easily adjusted.

The HLB (hydrophilic / hydrophobic group balance "Hydrophile-Lipophile Balance") is defined by the following formula (Griffin method).
・ HLB = 20 × (total formula weight of hydrophilic part / molecular weight)

Examples of such a surfactant include at least one selected from the group consisting of an ethylene oxide adduct of acetylene glycol and a polyether-modified silicone.

The ethylene oxide adduct of acetylene glycol is, for example, an —O- (CH ₂ CH ₂ O) n—H structure in which ethylene oxide is added to at least one hydroxyl group of acetylene glycol (for example, n is 1 or more and 30 or less. A compound with (indicating an integer),
Examples of commercially available products of ethylene oxide adducts of acetylene glycol (values in parentheses indicate HLB catalog values) include Orfin E1004 (7 to 9), Orfin E1010 (13 to 14), and Orfin EXP. 4001 (8-11), Orfin EXP. 4123 (11-14), Orfin EXP. Examples thereof include 4300 (10 to 13), Surfinol 104H (4), Surfinol 420 (4), Surfinol 440 (4), Dynol 604 (8) [above, Nissin Chemical Industry Co., Ltd.].

The polyether-modified silicone is, for example, a compound in which a polyether group is bonded in a graft shape or a compound in which a polyether group is bonded in a block shape to a silicone chain (polysiloxane main chain). Examples of the polyether group include a polyoxyethylene group and a polyoxypropylene group. The polyether group may be, for example, a polyoxyalkylene group in which an oxyethylene group and an oxypropylene group are added in a block shape or at random.
Commercially available products of polyether-modified silicone (values in parentheses indicate HLB catalog values) include Silface SAG002 (12), Silface SAG503A (11), and Silface SAG005 (7) [above, Nisshin. Chemical Industry Co., Ltd.] and the like.

Other surfactants other than the ethylene oxide adduct of acetylene glycol and the polyether-modified silicone may be used as the water-based ink.
Examples of other surfactants include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants and the like, preferably anionic surfactants and nonionic surfactants. be.

Anionic surfactants include alkylbenzene sulfonates, alkylphenylsulfonates, alkylnaphthalene sulfonates, higher fatty acid salts, higher fatty acid ester sulfates, higher fatty acid ester sulfonates, higher alcohol ether sulfates. Examples thereof include ester salts and sulfonates, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates and the like.
Among these, as the anionic surfactant, dodecylbenzene sulfonate, isopropylnaphthalene sulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, monobutylbiphenylsulfonate, dibutylphenylphenol Disulfonate or the like is preferable.

Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, and poly. Examples thereof include oxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, alkylalkanolamide, polyethylene glycol polypropylene glycol block copolymer, and acetylene glycol.
Among these, examples of the nonionic surfactant include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, and poly. Oxyethylene sorbitan fatty acid ester, fatty acid alkyrrole amide, polyethylene glycol polypropylene glycol block copolymer, and acetylene glycol are preferable.

Other nonionic surfactants include silicone-based surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers. Agents; biosurfactants such as spicrysporic acid, ramnolipide, lysolecithin; and the like.

The hydrophilic / hydrophobic balance (HLB) of other surfactants is preferably in the range of 3 or more and 20 or less in consideration of solubility and the like.

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

The total content of the surfactant is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, and 0.2% by mass or more and 3% by mass with respect to the water-based ink. More preferably, it is by mass or less.

(Other additives)
Other additives will be described.
The water-based ink may contain other additives.
Other additives include ink ejection improvers (polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethyl cellulose, carboxymethyl cellulose, etc.) and conductivity / pH regulators (potassium hydroxide, sodium hydroxide, lithium hydroxide). Alkali metal compounds such as), reactive diluting solvent, penetrant, pH buffer, antioxidant, antifungal agent, viscosity regulator, conductive agent, chelating agent, ultraviolet absorber, infrared absorber, etc. Can be mentioned.

(Other physical characteristics of water-based ink)
Other suitable physical characteristics of the water-based ink will be described.
The pH of the water-based ink is preferably in the range of 4 or more and 10 or less, and more preferably in the range of 5 or more and 9 or less.
Here, the pH of the water-based ink is 23 ± 0.5 ° C. and 55 ± 5% humidity. H. In the environment, the value measured by the pH / conductivity meter (MPC227 manufactured by METTLER TOLEDO) is adopted.

The conductivity of the water-based ink is, for example, in the range of 0.01 S / m or more and 0.5 S / m or less (preferably in the range of 0.01 S / m or more and 0.25 S / m or less, more preferably 0.01 S / m or more and 0). .20 S / m or less range).
The conductivity is measured by MPC227 (pH / Conductivity Meter, manufactured by METTLER TOLEDO).

(Recording device / recording method)
The recording apparatus according to the present embodiment accommodates each water-based ink of the ink set according to the present embodiment, and discharges each water-based ink onto a non-permeable recording medium, and a discharge head on the non-permeable recording medium. It is a recording device including a drying device for drying each ejected water-based ink.
According to the recording apparatus according to the present embodiment, the ejection step of ejecting each water-based ink of the ink set onto the impermeable recording medium and the drying of each aqueous ink ejected onto the impermeable recording medium are dried. A recording method having a process is realized.

The recording device according to the present embodiment may include an ink cartridge set that accommodates each water-based ink of the ink set according to the present embodiment and is made into a cartridge so as to be attached to and detached from the recording device.

[Recording device / Recording method]
Hereinafter, an example of the recording device and the recording method according to the present embodiment will be described with reference to the drawings. In the following description, ejecting water-based ink (to a target region) to a recording medium may be referred to as "image formation" or "image formation", and water-based ink to a recording medium. It may be referred to as "recording", "image recording", or "recording an image" that the ink is discharged, dried, and fixed.

FIG. 1 is a schematic configuration diagram showing a recording device according to the present embodiment.
The recording device 100 according to the present embodiment is composed of an image recording unit 10 for recording an image on the recording medium P, a preprocessing unit 20 for accommodating the recording medium P supplied to the image recording unit 10, and a preprocessing unit 20. It includes a buffer unit 30 for adjusting the amount of transport of the recording medium P supplied to the image recording unit 10. The buffer unit 30 is arranged between the image recording unit 10 and the preprocessing unit 20.

Further, the recording device 100 adjusts the transport amount of the post-processing unit 40 that accommodates the recording medium P discharged from the image recording unit 10 and the recording medium P discharged from the image recording unit 10 to the post-processing unit 40. The buffer unit 50 and the like are provided. The buffer unit 50 is arranged between the image recording unit 10 and the post-processing unit 40.

Further, the recording device 100 is provided between the image recording unit 10 and the buffer unit 50, and includes a cooling unit 60 for cooling the recording medium P carried out from the image recording unit 10.

The image recording unit 10 is, for example, a roll member (reference numeral omitted) that guides the recording medium P along the transport path R of the recording medium P, and the surface of the recording medium P that is conveyed along the transport path R of the recording medium P. The ejection head (first ejection head) 12A for ejecting water-based ink (droplets of water-based ink) and the ejection head 12A form the first image on the surface of the recording medium P, and the ejection head 12B performs the first image formation. A second image formation is performed on the back surface of the recording medium P after the image formation.

In the ejection heads 12A and 12B, for example, the effective recording area (the area where the nozzle for ejecting the water-based ink is arranged) is equal to or larger than the width of the recording medium P (the length in the direction intersecting (for example, orthogonal to) the conveying direction of the recording medium P). It is a long discharge head.
The ejection heads 12A and 12B are not limited to this, and are ejection heads that are shorter than the width of the recording medium P and move in the width direction of the recording medium P to eject water-based ink (so-called carriage method). ) May be the discharge head.

The ejection heads 12A and 12B may be a so-called thermal method in which droplets of water-based ink are ejected by heat, or may be a so-called piezoelectric method in which droplets of water-based ink are ejected by pressure, and are known. Things apply.

The ejection heads 12A and 12B include, for example, the ejection heads 12KA and 12KB that eject water-based ink onto the recording medium P to form a K (black) color image, and the ejection heads 12YA and 12YA that form a Y (yellow) color image. It has 12YB, discharge heads 12MA and 12MB for forming an M (magenta) color image, and discharge heads 12CA and 12CB for forming a C (cyan) color image, respectively. The ejection heads 12KA and 12KB, the ejection heads 12YA and 12YB, the ejection heads 12MA and 12MB, and the ejection heads 12CA and 12CB are in this order in the transport direction of the recording medium P (hereinafter, simply referred to as "paper transport direction"). (May be described), they are arranged from the upstream side to the downstream side so as to face the recording medium P. When K, Y, M, and C are not distinguished in the notation of the discharge head, K, Y, M, and C attached to the reference numerals are omitted.

The ejection heads 12KA, 12YA, 12MA, 12CA, 12KB, 12YB, 12MB, and 12CB are connected to the ink cartridges (not shown) of each color attached to and detached from the recording device 100 through the supply pipe (not shown), and the ink is ink. Ink of each color is supplied from the cartridge to each ejection head 12KA, 12YA, 12MA, 12CA, 12KB, 12YB, 12MB, 12CB.

The discharge heads 12A and 12B are not limited to the form in which the four discharge heads corresponding to each of the above four colors are arranged, and the discharge heads 12A and 12B are not limited to the form in which the four discharge heads corresponding to each of the above four colors are arranged. It may be in the form of arranging the discharge head.

Here, the ejection heads 12A and 12B include, for example, a low-resolution ejection head (for example, a 600 dpi ejection head) that ejects water-based ink in a range of ink droplet amount lpl or more and 15 pl or less, and an ink droplet amount of less than 10 pl. It may be any of high-resolution ejection heads (for example, 1200 dpi ejection heads) that eject water-based ink. Further, as the discharge heads 12A and 12B, both a discharge head for low resolution and a discharge head for high resolution may be provided.
The amount of ink droplets from the ejection heads 12A and 12B is in the range of the maximum amount of water-based ink droplets. In addition, dpi means "dot per inch".

Here, each of the discharge heads 12B (12KA, 12YA, 12MA, 12CA) and 12B (12KB, 12YB, 12MB, 12CB) has a heater (temperature control) for controlling the temperature of the head (temperature of the discharge surface). Example of device) 13A (13KA, 13YA, 13MA, 13CA), 13B (13KB, 13YB, 13MB, 13CB) are built-in. Then, the discharge heads 12A and 12B are adjusted to a target temperature by the heaters 13A and 13B, respectively, and the water-based ink is discharged.
The temperature control device for controlling the temperature of the head (the temperature of the discharge surface) is not limited to the heater, and any well-known temperature control device such as a device for blowing warm air may be used. Further, the temperature control device is not limited to the mode built in the discharge head, and may be provided outside the discharge head.

For example, the back surface of the recording medium P is wound around the image recording unit 10 on the downstream side in the paper transport direction with respect to the ejection head 12A, and the image of the front surface of the recording medium is imaged while being driven to rotate in contact with the recording medium P. A drying drum 14A (an example of a drying device) for drying (ink) is arranged.
Similarly, for example, the surface of the recording medium P is wound around the image recording unit 10 on the downstream side in the paper transport direction with respect to the ejection head 12B, and the surface of the recording medium P is in contact with the recording medium P for recording while driven rotation. A drying drum 14B (an example of a drying device) for drying an image (ink) on the back surface of the medium is arranged.
A transport roller 18 that comes into contact with the surface of the recording medium P is arranged on the downstream side of the drying drum 14A in the paper transport direction and on the upstream side of the discharge head 12B in the paper transport direction.

A heating source (for example, a halogen heater or the like: not shown) is built in the drying drums 14A and 14B. The drying drum 14A dries the image (ink) of the front surface of the recording medium P by heating with a heating source, and the drying drum 14B dries the image (ink) of the back surface of the recording medium P by heating with a heating source.

Around the drying drums 14A and 14B, warm air blowers 16A and 16B (an example of the drying device) for drying the image (ink) on the recording medium P are arranged, respectively. The image (ink) of the surface of the recording medium P wound around the drying drum 14A by the warm air from the warm air blower 16A is wound around the drying drum 14B by the warm air from the warm air blower 16B. The image (ink) on the back surface of the recording medium P is dried.

When a drying device that performs heat drying as described above is used, the drying conditions are preferably as follows.
That is, for example, the temperature of the heating source of the drying drum and the temperature of the hot air of the hot air blower are 40 ° C. or higher and 120 ° C. or lower from the viewpoint of accelerating the drying of the water-based ink and suppressing the deformation of the recording medium P. It is preferably in the range, more preferably in the range of 60 ° C. or higher and 100 ° C. or lower.
The drying temperature conditions may be the same for the drying drum 14A and the drying drum 14B, and may be the same for the hot air blower 16A and the warm air blower 16B, or may be different.

Here, the drying device in the image recording unit 10 has the same configuration for the front surface of the recording medium P (drying drum 14A, warm air blower 16A) and for the back surface of the recording medium P (drying drum 14B, warm air blower 16B). However, the configuration is not limited to this, and different configurations may be used.

The image recording unit 10 has a near-infrared heater (not shown) and a laser on the downstream side of the ejection heads 12A and 12B in the paper transport direction to dry the image (ink) on the base layer of the recording medium P. Other drying devices such as an irradiation device may be arranged. Other drying devices such as near-infrared heaters, laser irradiators, etc. may be arranged in place of at least one of the drying drums 14A, 14B and the warm air blower 16A, 16B, or the drying drums 14A, 14B and the temperature. It may be arranged in addition to the air blowers 16A and 16B.

The preprocessing unit 20 includes a supply roll 20A around which a recording medium P supplied to the image recording unit 10 is wound, and the supply roll 20A is rotatably supported by a frame member (not shown).

In the buffer unit 30, for example, a first pass roller 30A, a dancer roller 30B, and a second pass roller 30C are arranged along the paper transport direction. The dancer roller 30B adjusts the tension of the recording medium P conveyed to the image recording unit 10 and the amount of the recording medium P conveyed by moving up and down in FIG.

The post-processing unit 40 includes a winding roll 40A as an example of a transport unit that winds the recording medium P on which an image is recorded. The take-up roll 40A receives a rotational force from a motor (not shown) and rotates, so that the recording medium P is conveyed along the transfer path R.

In the buffer unit 50, for example, a first pass roller 50A, a dancer roller 50B, and a second pass roller 50C are arranged along the paper transport direction. The dancer roller 50B adjusts the tension of the recording medium P discharged to the post-processing unit 40 and the amount of the recording medium P conveyed by moving up and down in FIG.

A plurality of cooling rollers 60A are arranged in the cooling unit 60. The recording medium P is cooled by transporting the recording medium P between the plurality of cooling rollers 60A.

Here, the recording speed in the recording device 100, that is, the transport speed of the recording medium is not particularly limited, but is high speed of 10 m / min or more because the drying device for drying the water-based ink ejected to the recording medium is provided. May be.

Next, the operation (recording method) by the recording device 100 will be described.
In the recording device 100 according to the present embodiment, first, the recording medium P is conveyed from the supply roll 20A of the preprocessing unit 20 to the image recording unit 10 through the buffer unit 50.
Next, in the image recording unit 10, water-based ink is ejected from each ejection head 12A to the surface of the recording medium P. Then, the image (ink) on the front surface of the recording medium P is dried by the drying drum 14A from the back surface side of the recording medium P (the surface opposite to the ink ejection surface from the ejection head 12A). Then, the ink (image) ejected on the surface of the recording medium P is dried by the warm air blower 16A from the surface side of the recording medium P (the ink ejection surface side from the ejection head 12A). That is, the water-based ink discharged on the surface of the recording medium P is dried by the drying drum 14A and the warm air blower 16A.
Then, the image recorded on the surface of the recording medium P comes into contact with the transport roller 18 to eliminate static electricity from the recording medium P through the image.
Subsequently, in the image recording unit 10, water-based ink is ejected from each ejection head 12B to the back surface of the recording medium P. Then, the image (ink) on the back surface of the recording medium P is dried by the drying drum 14B from the front surface side of the recording medium P (the surface opposite to the ink ejection surface from the ejection head 12B). Then, the ink (image) ejected to the back surface of the recording medium P is dried by the warm air blower 16B from the back surface side (ink ejection surface side from the ejection head 12B) of the recording medium P. That is, the water-based ink discharged to the back surface of the recording medium P is dried by the drying drum 14B and the warm air blower 16B.
Next, in the cooling unit 60, the recording medium P on which the image is recorded is cooled by the cooling roller 60A.
Next, through the buffer unit 50, the post-processing unit 40 winds up the recording medium P on which the image is recorded on the surface by the winding roll 40A.

Through the above steps, an image with water-based ink is recorded on both sides of the recording medium P.
If necessary, the recording medium P including the image recorded as described above is cut to a target size through a cutting step.

The recording device 100 has described a configuration including a ejection head 12A for ejecting water-based ink on the front surface of the recording medium P and an ejection head 12B for ejecting water-based ink on the back surface of the recording medium P. I can't. For example, the recording device 100 does not include the ejection head 12B, and after ejecting the water-based ink onto the surface of the sheet of paper as the recording medium P by the ejection head 12A, the recording medium P is inverted by a mechanism for inverting the recording medium P, and then again. The ejection head 12A may be configured to eject water-based ink to the back surface of the recording medium P.

In the recording apparatus 100, a method of directly ejecting a droplet of water-based ink onto the surface of the recording medium P by the ejection heads 12A and 12B has been described, but the present invention is not limited to this, and the droplet of water-based ink is ejected to, for example, an intermediate transfer body. Later, a method may be used in which the droplets of the water-based ink on the intermediate transfer body are transferred to the recording medium P.

The recording device 100 includes a recording device for the front surface of the discharge head 14A and the recording medium P (drying drum 14A, warm air blower 16A), and a recording device for the back surface of the discharge head 14B and the recording medium P (drying drum 14B, The hot air blower 16B) was configured to be all in the same image recording unit 10, but the configuration is not limited to this. For example, the recording device 100 has two image recording units, one of which is provided with a discharge head 14A and a recording device (drying drum 14A, warm air blower 16A) for the surface of the recording medium P, and the other is a discharge head. A recording device (drying drum 14B, warm air blower 16B) for the back surface of the recording medium P and 14B may be provided.

In the recording apparatus 100, a method of ejecting water-based ink onto a roll-shaped recording medium P (so-called continuous paper) and recording an image after drying has been described. For example, the water-based ink is applied to a sheet of paper of a target size. A method may be used in which an image is recorded after being discharged and dried.

It goes without saying that the above-described embodiment is not limited to that embodiment and is realized within a range that satisfies the requirements of the present invention.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

<Example 1>
(Cyan ink; written as "C ink")
・ C. I. Pigment Blue 15: 3 (colorant): 4% by mass
-Styrene / acrylic acid copolymer sodium neutralized product: 2.5% by mass
(Water-soluble resin: weight average molecular weight = 30,000)
-Propylene glycol: 10% by mass
・ Diethylene glycol: 5% by mass
-Water: Remaining After sufficiently mixing the above components, the following components were added to the mixture.
-TOCRYL W-4627: 2.5% by mass (solid content)
(Polymer particles: "Acrylic emulsion" manufactured by Toyochem Co., Ltd., volume average particle size = 0.12 μm, glass transition temperature = 45 ° C.)
-Surfactant ("Orfin E1010" Nissin Chemical Industry Co., Ltd.): 1.0% by mass
-Surfactant ("Orfin EXP.4123" Nissin Chemical Industry Co., Ltd.): 1.0% by mass
Surfactant ("Silface SAG002" Nissin Chemical Industry Co., Ltd.): 0.1% by mass
Then, the obtained mixture was filtered through a 5 μm filter to obtain a water-based ink (C ink).

(Magenta ink; written as "M ink")
As a colorant, C.I. I. Pigment Red 122: M ink is obtained in the same manner as C ink except that 5% by mass is used and the amount of surfactant (“Orfin E1010” Nissin Chemical Industry Co., Ltd.) is changed to 1.2% by mass. rice field.

(Yellow ink; Y ink ")
As a colorant, C.I. I. Pigment Yellow 74: Y ink was obtained in the same manner as C ink except that 4% by mass was used.

(Ink set)
The obtained C ink, M ink, and Y ink were used as the ink set of Example 1.

<Examples 2 to 5, Comparative Examples 1 to 5>
According to Tables 1 and 2, the type and amount (mass%) of the surfactant and the amount (solid content: mass%) of the polymer particles (TOCRYL W-4627 “acrylic emulsion” manufactured by Toyochem Co., Ltd.) were changed. Except for the above, an ink set was prepared in the same manner as in Example 1.

<Evaluation>
(Measurement of physical properties of each ink)
The physical characteristics of each ink in each example were measured according to the method described above. The results are shown in Tables 1 to 3.

(Preparation of recording device)
A recording device including a 600 dpi piezo head (maximum ink droplet amount 12 pl) piezo head as an ink ejection head and a near infrared heater as a drying device was prepared. The details of the prepared recording device are as follows.
-Details of recording device-
-Recording speed (recording medium transport speed): 100 m / min
・ Set temperature of near infrared heater: 60 ℃

Then, the ink of each color of the ink set of each example was filled in the ink tank of each color of the recording device. The following image recording (hereinafter referred to as "printing") was performed using this recording device.

(Evaluation of intercolor bleeding and uneven density)
Using each recording device, a person image including an image in which a solid print pattern with 100% coverage of each color partially overlaps on a non-penetrating recording medium (sheet sheet: Oji Paper "OK Top Coat +") and a shadow. The print chart in which the above was placed was printed. Then, the obtained chart was visually evaluated according to the following evaluation criteria.
G1: No intercolor bleeding between print patterns by each ink and inconspicuous density unevenness G2: No intercolor bleeding between print patterns by each ink and slight density unevenness can be seen G3: Between print patterns by each ink Color bleeding is slightly seen in, and density unevenness is also seen slightly. G4: Color bleeding and density unevenness are severe between print patterns by each ink.

(Evaluation of continuous discharge stability)
Using each recording device, a chart with a print coverage of 8% for each color in one page was printed 4000 m on a non-penetrating recording medium (continuously printed paper: Nippon Paper Industries "NPiform Next-IJ70"). The state of occurrence of streaks was visually evaluated according to the following evaluation criteria.
G1: In printing with each ink, the state of streaks has not changed from the initial stage. G2: Streaks become slightly noticeable in printing with each ink. G3: New streaks are slightly generated in printing with each ink. G4: In printing with each ink, streaks are conspicuous and many new streaks are generated.

From the above results, it can be seen that the ink set of this example has less intercolor bleeding with respect to the impermeable recording medium than the ink set of the comparative example. It can also be seen that there is little unevenness in density.
It can be seen that the ink set of Example 1 and the like having a high “dynamic contact angle after 1 sec” of each ink has higher ejection stability than the ink set of Example 4. That is, it can be seen that the ejection failure of the water-based ink that occurs when continuously recording is suppressed.
It can be seen that the ink set of Example 1 and the like in which the difference between the dynamic contact angles of the inks is small has less intercolor bleeding than the ink set of Example 3. It can also be seen that there is little unevenness in density.
From the comparison of the ink sets of Example 1 and the like with Comparative Example 4 and the comparison of the ink sets of Comparative Example 3 and Comparative Example 4, the ink set having a high static surface tension of each ink has high ejection stability. You can see that. That is, it can be seen that the ejection failure of the water-based ink that occurs when continuously recording is suppressed.

The details of the abbreviations and the like in Tables 1 to 3 are as follows.
-Ethylene oxide adduct of acetylene glycol (Nissin Chemical Industry Co., Ltd.)-
-Orfin E1004 (HLB = 7-9)
-Orfin E1010 (HLB = 13-14)
・ Orfin EXP. 4001 (HLB = 8-11)
・ Orfin EXP. 4123 (HLB = 11-14)
・ Orfin EXP. 4300 (HLB = 10-13)
-Polyether-modified silicone (Nisshin Kagaku Kogyo Co., Ltd.)-
・ Silface SAG002 (HLB = 12)
・ Silface SAG503A (HLB = 11)

10 Image recording unit 12A, 12KA, 12YA, 12MA, 12CA Discharge head 12B, 12KB, 12YB, 12MB, 12CB Discharge head 14A Dry drum 14B Dry drum 16A Hot air blower 16B Hot air blower 20 Pretreatment unit 20A Supply roll 30 Buffer unit 30A 1st pass roller 30B Dancer roller 30C 2nd pass roller 40 Post-processing unit 40A Take-up roll 50 Buffer unit 50A 1st pass roller 50B Dancer roller 50C 2nd pass roller 60 Cooling unit 60A Cooling roller 100 Recording device P Recording medium R Conveyance path

Claims (6)

It has multiple color water-based inks that contain colorants, polymer particles, water, and water-soluble organic solvents and are different in color from each other.
The multicolor water-based inks each contain an ethylene oxide adduct of two or more acetylene glycols and a surfactant containing a polyether-modified silicone.
Only two or more and four or less ethylene oxide adducts of acetylene glycol having an HLB of 14 or less and one type of polyether-modified silicone having an HLB of 14 or less are used as the surfactant.
The static surface tensions of the water-based inks of the plurality of colors are 30 mN / m or less, respectively.
When the dynamic surface tension was measured by the maximum foam pressure method, it was the dynamic surface tension of the water-based ink after 5 msec, and the dynamic surface tension of the water-based inks of the plurality of colors was 34 mN / m or less, respectively.
When 2 μl of water-based ink is dropped on a recording medium having a transfer amount of pure water to a recording medium of 3 to 15 ml / m ² at a contact time of 100 msec measured by a dynamic scanning liquid absorber, the dynamic of the water-based ink after 2 msec. The contact angle is such that the difference between the dynamic contact angles of the water-based inks of the plurality of colors is within 2 °.
When 2 μl of water-based ink is dropped on a recording medium having a transfer amount of pure water to a recording medium of 3 to 15 ml / m ² at a contact time of 100 msec measured by a dynamic scanning liquid absorber, the dynamic of the water-based ink after 2 msec. The contact angle is such that the dynamic contact angles of the water-based inks of the plurality of colors are 48 ° or more and 54 ° or less, respectively.
When 2 μl of water-based ink is dropped on a recording medium having a transfer amount of pure water to a recording medium of 3 to 15 ml / m ² at a contact time of 100 msec measured by a dynamic scanning liquid absorber, the dynamic of the water-based ink after 1 sec. An ink set having a contact angle of 14 ° or more and 21 ° or less, respectively, in which the dynamic contact angles of the water-based inks of the plurality of colors are 14 ° or more and 21 ° or less. The ink set according to claim 1, wherein the difference between the dynamic surface tensions of the water-based inks of a plurality of colors is within 3 mN / m. The ink set according to claim 1 or 2, wherein the static surface tensions of the water-based inks of the plurality of colors are 25 mN / m or more, respectively. An ink cartridge set containing each water-based ink of the ink set according to any one of claims 1 to 3. An ejection head that accommodates each water-based ink of the ink set according to any one of claims 1 to 3 and ejects each of the water-based inks onto a non-permeable recording medium.
A drying device for drying each of the water-based inks ejected onto the impermeable recording medium, and a drying device.
A recording device equipped with. A ejection step of ejecting each water-based ink of the ink set according to any one of claims 1 to 3 onto a non-permeable recording medium.
A drying step of drying each of the water-based inks ejected onto the impermeable recording medium, and
Recording method having.

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