JP2022048513A - Printing method, printer, and ink set - Google Patents

Abstract

To provide a printer that can give a printed material having good uniformity in gloss between color ink layers of different colors and having a good gloss.SOLUTION: A printer includes color ink application means for applying a color ink containing at least one colorant onto a recording medium to form a color ink layer, and clear ink applying means for applying a clear ink containing at least polymer particles onto the color ink layer. The clear ink has a wet energy of 40 mJ/m2 or more on the color ink layer.SELECTED DRAWING: None

Description

The present invention relates to a printing method, a printing apparatus, and an ink set.

In recent years, in an inkjet recording method, an image having high resolution and high color development as realized by silver halide photography and offset printing has been desired.

In such an inkjet recording method, a water-based color ink in which a pigment as a coloring material and other additives are dispersed in water is generally used. Since the pigment has a composition similar to that of a coloring material used in general commercial printing inks, it is expected that the texture of printed matter will be closer to that of commercial printing. However, when recording on coated paper for commercial printing or publishing printing using a water-based color ink, the coloring material exists as particles in the solvent, so that it is difficult to penetrate into the recording medium and the pigment remains on the surface of the recording medium. There is a problem that it is easy.
In this case, in an inkjet recording device, full color is often expressed by combining four color inks of Y (yellow), M (magenta), C (cyan), and K (black), but the image density and color are changed. In addition to the amount of pigment used in the ink differs depending on the amount of pigment used, the pigment remains on the surface of the recording medium in the printed matter, so that the surface smoothness differs depending on the image density and color, and diffused reflection of light occurs, resulting in uneven gloss. There is a problem that it arises.

Here, the gloss unevenness means a state in which a region having a high glossiness (gloss region) and a region having a low glossiness (matte region) coexist in the printed matter. When gloss unevenness occurs, a gloss region and a matte region coexist in the same image, and in particular, in the case of a photographic image, it is visually recognized as an image defect.

In order to solve the problem of uneven gloss, it has been attempted to use a substantially colorless and transparent ink (hereinafter, may be referred to as "clear ink") that does not affect the color reproducibility. For example, it has been proposed to improve the glossiness of a non-printed portion and a low duty portion of a color ink image by using a clear ink containing a cationic resin and polymer particles having a specific structure (see, for example, Patent Document 1). ).
Further, it has been proposed to adjust the dot diameter of the clear ink by controlling the ejection amount of the clear ink to improve the glossiness (see, for example, Patent Document 2).

In addition, we have proposed an inkjet recording method that can obtain high-gloss image quality close to that of silver halide photography by using color ink with high permeability and clear ink in combination with a recording medium with high surface gloss and low ink permeability. (See, for example, Patent Document 3).

An object of the present invention is to provide a printing apparatus capable of obtaining a printed matter having excellent gloss uniformity between color ink layers of each color and having excellent gloss.

The printing apparatus of the present invention as a means for solving the above-mentioned problems includes a color ink applying means for forming a color ink layer by applying a color ink containing at least one kind of color material on a recording medium, and the color. It has a clear ink applying means for applying clear ink containing at least polymer particles on the ink layer, and the clear ink has a wetting energy of 40 mJ / m ² or more with respect to the color ink layer.

According to the present invention, it is possible to provide a printing apparatus capable of obtaining a printed matter having excellent gloss uniformity between color ink layers of each color and having excellent gloss.

FIG. 1 is a perspective explanatory view showing an example of a printing apparatus. FIG. 2 is a perspective explanatory view showing an example of a main tank in a printing apparatus. FIG. 3 is a diagram illustrating the wetting energy of the clear ink with respect to the color ink layer. FIG. 4 is a diagram illustrating the measurement of the contact angle between a solid and a liquid. FIG. 5 is an explanatory diagram of a method of obtaining the surface free energy of a color ink layer (solid) based on the Fowkes-Owens model. FIG. 6 is a diagram illustrating a method for measuring the static surface tension of a liquid sample by the Wilhelmy method. FIG. 7 is an image including a solid image of four colors of each color used for forming the color image in the embodiment.

(Printing method and printing equipment)
The printing apparatus of the present invention contains a color ink applying means for applying a color ink containing at least one kind of color material on a recording medium to form a color ink layer, and at least polymer particles on the color ink layer. It has a clear ink applying means for applying clear ink, and the clear ink has a wetting energy of 40 mJ / m ² or more with respect to the color ink layer, and further has other means as needed.

The printing method of the present invention includes a color ink applying step of applying a color ink containing at least one kind of color material on a recording medium to form a color ink layer, and a color ink applying step of applying at least polymer particles on the color ink layer. A clear ink applying step of applying clear ink is included, and the clear ink has a wetting energy of 40 mJ / m ² or more with respect to the color ink layer, and further includes other steps as necessary.

The printing method of the present invention can be suitably carried out by the printing apparatus of the present invention, the color ink applying step can be performed by the color ink applying means, and the clear ink applying step can be performed by the clear ink applying means. , Other steps can be performed by other means.

In the prior art described in Patent Document 1 (Patent No. 4096158) and Patent Document 2 (Japanese Patent Laid-Open No. 2004-306557), the surface tension of the clear ink is reduced by the surfactant from the viewpoint of ejection stability. Since the clear ink is promoted to penetrate into the recording medium, a polymer film cannot be formed on the surface of the recording medium, and uniform gloss cannot be obtained.
Further, in the conventional technique described in Patent Document 3 (Japanese Patent No. 509603), the wettability of the clear ink with respect to the color ink layer is not optimized, so that even if the clear ink is dropped on the color ink layer. Repelling occurs, the clear ink does not get wet and spread, and after drying, fine irregularities are formed by the polymer particles contained in the clear ink, resulting in a printed matter having uneven gloss.

In the present invention, the clear ink is adjusted so that the wetting energy with respect to the color ink layer is 40 mJ / m ² or more, preferably 40 mJ / m ² or more and 65 mJ / m ² or less, and thereby the color ink layers of each color. Excellent gloss uniformity, excellent gloss, and image quality printed matter with a texture close to that of silver salt photographs can be obtained.
Further, in the present invention, preferably, the color ink has at least black ink, yellow ink, magenta ink, and cyan ink, and the surface free energy of the color ink layer of each color formed by the color ink. When the dispersion component of is γ _s ^d and the polar component of the surface free energy of the color ink layer of each color is γ _s ^p , the maximum difference of the dispersion component γ _s ^d between the color ink layers of each color is 0.3 mJ / m ² or more. By designing so that the maximum difference of the polar component γ sp in the color ink layer of each color is 5 ^mJ / _m ² or less, the uneven gloss between the color ink layers of each color is eliminated, and the texture is close to that of a silver salt photograph. Image quality prints are obtained.
Further, since the type and content of the pigment contained in the color ink differs depending on the image density and color, even if the gloss uniformity is lowered between the color ink layers of each color, the clear ink has high wettability to the color ink layer. By applying clear ink to the color ink layer, the glossiness of the image can be significantly improved.

When discussing the wettability of a clear ink with respect to a color ink layer of each color, prior art documents have adopted static surface tension and / or dynamic surface tension of the color ink and the clear ink in their respective liquid states. However, even if the physical property values of the color ink and / or the clear ink in the liquid state were controlled, when the image was actually formed, a uniform high-gloss image could not be obtained.
Therefore, as a result of diligent studies by the present inventors, the concept of wet energy for each color ink layer of clear ink was introduced, and a printing technique having excellent gloss uniformity was found based on a new design concept. It led to the invention.

In order for the polymer particles contained in the clear ink to cover the surface of the color ink layer and form a uniform glossy surface, the clear ink must completely wet the surface of the color ink layer of each color. In the present invention, how much energy the clear ink adheres to the surface of the color ink layer, conversely, the adhesive energy (= adhesive work) that can be rephrased as the energy required to separate the adhesive interface. The study was conducted using the peeling energy (= peeling work) as an index.

First, the adhesive energy Wa will be described with reference to FIG.
When the liquid column and the solid column are separated, the liquid surface and the solid surface are born, and the surface always has surface free energy. Therefore, the energy in the system after the separation is the surface free energy γ _L of the liquid and the surface free energy of the solid. It is the sum of the energy γ _S. Since the energy existing in the system before separation is the interface energy γ _LS possessed by the interface between the solid and the liquid, the sum of the surface free energy γ _L of the liquid and the surface free energy γ _S of the solid shows that the solid and the liquid. The value obtained by subtracting the interfacial energy γ _LS is the adhesion energy Wa (Work of adhesion) required for peeling, and this relationship is shown by the Dupre equation of the following equation (1).
Here, the adhesion energy or the peeling energy is treated as "wetting energy" Wa in the system of the solid surface and the droplet.

ただし、前記式（１）中、γ_Ｓはカラーインク層の表面自由エネルギー、γ_Ｌはクリアインクの表面自由エネルギー、γ_ＬＳはカラーインク層に着滴させたクリアインクの界面エネルギー、θはクリアインク液滴の接線とカラーインク層とのなす角度である。

However, in the above formula (1), γ _S is the surface free energy of the color ink layer, γ _L is the surface free energy of the clear ink, γ _LS is the interface energy of the clear ink dropped on the color ink layer, and θ is clear. It is the angle formed by the tangent line of the ink droplet and the color ink layer.

Here, the surface free energy γ _L of the liquid is synonymous with the static surface tension of the liquid, and can be measured by using, for example, an automatic surface tensiometer. However, a method for measuring the interface energy γ _LS at the interface between a solid and a liquid has not yet been established.

On the other hand, when the substances are a solid and a liquid, assuming that the droplets reach equilibrium on the surface of the solid while maintaining the contact angle θ as shown in FIG. 4, the Young equation represented by the following equation (2) holds.

By combining the above Dupre equation (1) and the above Young (2), it is shown by the following equation (3), which consists of the static surface tension of the liquid and the contact angle θ at which the droplet reaches equilibrium on the solid surface. Since the Young-Dupre equation is obtained, the wetting energy Wa can be obtained.

Here, the wet energy Wa in the present invention can be obtained by the following method.

The image of the color ink was formed by using IPSiO GX e5500 (manufactured by Ricoh Co., Ltd.) under environmental conditions of 23 ° C. ± 0.5 ° C. and 50 ± 5% RH. In advance, a single color 5 cm x 20 cm rectangular solid image is printed on Super Fine paper (manufactured by Epson Corporation), which is an inkjet paper, with a resolution of 1,200 dpi and an ink adhesion amount of 0.96 mg / cm ² (600 mg / A4 size). ), The drive voltage of the piezo element is changed to print, and the amount of ink adhered is adjusted. At this time, each color ink of each color is individually set so that the amount of ink adhered is the same. The amount of ink adhered can be obtained by measuring the mass of the Super Fine paper before and after printing the rectangular solid image. As the print mode, select "Paper type: Glossy paper", "Print quality: Beautiful", and "Color matching: No" according to the user settings of the driver attached to the printer.
Next, coated paper (OK top coat +, basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.) is set under the above-mentioned set conditions, and is produced by Microsoft Word 2016 (manufactured by Microsoft). As shown in FIG. 7, a solid image consisting of one set of four colors was printed at a resolution of 1,200 dpi, and then the internal temperature was set to 90 ° C. after printing the four-color image as one image. Dry in a constant temperature bath for 30 seconds.
Arithmetic mean height of a color ink image printed on coated paper (OK top coat +, basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd .): Ra is 1.50 μm to 1.65 μm. The arithmetic mean roughness Ra is measured using a shape analysis laser microscope (VK-9510, manufactured by KEYENCE CORPORATION) at a magnification of 50. The average value when 5 points are measured for the same sample is adopted as the value of Ra.

<Method of finding the contact angle θ of clear ink>
The method of obtaining the contact angle θ of the clear ink landed on the surface of the color ink image will be described in detail below.
Here, after printing a color solid image of each color created by Microsoft Word 2016 (manufactured by Microsoft) under the printing conditions set above, clear ink is dropped on the color solid image, and the contact angle is set after the drops. The value at 1,000 ms is adopted.
A contact angle meter (DMo-501, manufactured by Kyowa Interface Science Co., Ltd.) was used for measuring the contact angle. In this contact angle meter, a droplet of a measurement sample (clear ink) can be dropped on the surface of a color image, and the contact angle of the clear ink can be measured from the image of the dropped droplet.
The contact angle is measured in an environment of 25 ° C. A drop of clear ink to be dropped is formed on the needle tip of a syringe, and the amount of the drop is adjusted to 2.0 μL. Gently raise the sample table on which the color ink image is placed, drop it on the surface of the color ink image, capture the image 1,000 msec after the droplets formed on the surface of the color ink image, and analyze the attached device. The contact angle is obtained by the θ / 2 method using the software "FAMAS (interFace Imagement & Analysis System". The number of measurements is 3 times or more, and the average value is used as the contact angle in the sample.

<Method of determining the static surface tension of a liquid>
The method for measuring the static surface tension of a liquid will be described in detail below.
Here, the static surface tension γ _L of the liquid decreases as the temperature of the liquid rises. This is because when the temperature of the liquid rises, the intramolecular distance of the liquid increases due to the thermal motion of the liquid, and the intramolecular aggregation energy decreases. The measurement conditions for the static surface tension of clear ink are shown below. The static surface tension of clear ink is measured in a fully automatic mode of an automatic surface tension meter (DY-300, manufactured by Kyowa Interface Science Co., Ltd.) in an environment of 25 ° C. Detailed measurement conditions are shown in Table A below.

Hereinafter, a method for measuring the static surface tension of a liquid will be described in detail.
The surface tension of a liquid is a method of creating a sample droplet at the tip of a needle and calculating the surface tension by image analysis from the state of the liquid itself's limit size droplet (pendant drop method (suspension method)). A ring method that calculates surface tension by immersing a ring in a liquid and measuring the force applied to the balance when it is released. There is a Wilhelmy method (plate method) that calculates the surface tension by measuring the force to be applied with a balance that is a weight sensor.
In the present invention, an automatic surface tension meter (DY-300, manufactured by Kyowa Interface Science Co., Ltd.) is used, and the static surface tension of a liquid sample: γL is calculated by the following mathematical formula (i) by the Wilhelmy method.

ただし、前記数式（ｉ）中、γＬは液体サンプルの静的表面張力（ｍＮ／ｍ）、Ｆは白金プレートに働く力（ｍＮ）、Ｌは白金プレートの周囲の長さ（ｍ）、θは白金プレートと液体サンプルとの接触角を表す。

However, in the above formula (i), γL is the static surface tension (mN / m) of the liquid sample, F is the force acting on the platinum plate (mN), L is the length around the platinum plate (m), and θ is Represents the contact angle between the platinum plate and the liquid sample.

Since most liquids are sufficiently wet with the platinum plate, it can be assumed that the contact angle θ = 0 °, that is, cos θ = 1, and the surface tension is as shown in the following formula (ii).

ただし、前記数式（ｉｉ）中、Ｆは白金プレートに働く力（ｍＮ）、Ｌは白金プレートの周囲の長さ（ｍ）を表す。

However, in the above formula (ii), F represents the force acting on the platinum plate (mN), and L represents the length around the platinum plate (m).

As mentioned above, when calculating the surface tension assuming that the contact angle between the platinum plate and the liquid sample is zero, the platinum plate needs to be completely wet, but in reality, the wetting may not be sufficient. Therefore, after immersing the platinum plate once (pre-wet), the operation of pulling it up again was performed.
Under 25 ° C environmental conditions, put 10 mL of each color ink in a petri dish with a diameter of 40 mm, adjust the zero point, and then immerse the platinum plate, which is a stylus, in the liquid sample in the petri dish once (pre-wet). , All of the series of operations to start the measurement are automatically performed (see FIG. 6).
Static surface tension: For γ _L , the average value of 5 times is adopted, and the contaminants on the plate surface are removed by washing the platinum plate with distilled water and washing with red heat for about 30 seconds for each measurement. use.

In the present invention, examples of the method for controlling the numerical range of the wet energy Wa include the type of the surfactant, the amount of the surfactant added, and the adjustment of the mixing ratio of the plurality of types of the surfactant.

Next, the color ink has at least black ink, yellow ink, magenta ink, and cyan ink, and the dispersion component of the surface free energy of the color ink layer of each color formed by the color ink is γ _s ^{d. Assuming} that the polar component of the surface free energy of the color ink layer of each color is γ _{sp, the maximum difference of the dispersion component γ s d} ^between the color ink layers of each color is 0.3 mJ / m ² or more, and the color ink of each color It is preferable that the maximum difference of the polar component γ sp in the layer is 5 ^mJ / _m ² or less.
Here, the dispersion component γ _S ^d and the polar component ^γ _SP of the surface free energy in the color ink layer of each color can be measured as follows.

The wetting energy (adhesive work) Wa represented by the above formula (3) can be expressed as a root mean square between a solid and a liquid as shown by the following formula (4).

Therefore, from the above formula (3) and the above formula (4), the formula of Young-Dupre represented by the following formula (5) can be obtained.

Here, the Young-Dupre equation of the above equation (5) can be modified as shown in the following equation (6) by dividing both sides by 2√γ _L ^d .

From the above equation (6), the surface free energy γ _S of the color ink layer of each color can be obtained. This point will be described with reference to FIG.
First, as the probe liquid, two types of probe liquids whose surface free energy dispersion component and polar component are known, which are shown in Table B, are used, and the contact angle on the color ink layer of each color is measured.
In the present invention, pure water having a high polar component of surface free energy and methylene iodide having a high dispersion component of surface free energy were used as the two types of probe liquids.
Below, Table B shows the values of each component of the surface free energy of pure water and methylene iodide.

Next, based on the above formula (6), the dispersion component γ _S ^d of the surface free energy of the color ink layer can be obtained from the intercept of the graph of FIG. From the slope of the graph of FIG. 5, the polar component _γ ^SP of the surface free energy of the color ink layer can be obtained.
Then, the surface free energy γ _S of the color ink layer can be obtained as the sum of the obtained dispersion component ^γ _S ^d and the polar component γ _Sp .

Hereinafter, the clear ink, the color ink, and the ink set used in the printing apparatus of the present invention and the printing method of the present invention will be described.

<Clear ink>
The clear ink means a colorless and transparent ink that does not substantially contain a coloring material. Here, the fact that the coloring material is not substantially contained means that the content of the coloring material is 0.5% by mass or less, and may be contained as long as it contains impurities.
The clear ink contains at least polymer particles, preferably an organic solvent, water, and a surfactant, and further contains other components as needed.

-Polymer particles-
The polymer particles used in the color ink are dispersed in a solvent as a polymer emulsion, and may contain a dispersant or the like, if necessary.
The polymer emulsion is not particularly limited and may be appropriately selected depending on the intended purpose. For example, acrylic resin, urethane resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, etc. Examples thereof include vinyl chloride resin, acrylic-styrene resin, acrylic-silicone resin and the like.
As the polymer emulsion, an appropriately synthesized one may be used, or a commercially available product may be used. Further, these may be used alone or in combination of two or more kinds of resin particles.

The cumulative 50% volume particle diameter (D ₅₀ ) of the polymer particles is preferably 0.5 μm (= 500 nm) or more, preferably no coarse particles of 0.5 μm (= 500 nm) or more, more preferably 30 nm or more and 200 nm or less, still more preferably 50 nm or more and 100 nm or less.
When the cumulative 50% volume particle diameter (D ₅₀ ) is 200 nm or less, the ejection stability of the clear ink is good. Further, when the polymer particles in the polymer emulsion have a crosslinked structure, the polymer particles are in the process of forming a film after the clear ink is applied to the recording medium, while the aqueous medium in the clear ink permeates the recording medium. May not fuse with each other and good gloss may not be obtained.
The cumulative 50% volume particle diameter (D ₅₀ ) is a particle diameter corresponding to 50% of the volume distribution cumulative amount of the particle size distribution curve obtained by the dynamic light scattering method.
Specifically, the polymer emulsion can be diluted to a solid content of 0.01% by mass or more and 0.1% by mass or less, and measured using "Microtrac UPA" (manufactured by Leeds & Northrup).

The content of the polymer particles in the clear ink [content of the polymer particles in the clear ink (solid content)] is preferably 10% by mass or more and 30% by mass or less, and more preferably 10% by mass or more and 20% by mass or less.
When the content of the polymer particles is 10% by mass or more, gloss can be imparted to the image. Further, when it is 30% by mass or less, the ejection stability of the clear ink is good. If the content of the polymer particles exceeds 30% by mass, the inkjet nozzle may be clogged depending on the emulsion, which may cause a problem in ejection reliability.
The content of the polymer particles in the polymer emulsion is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 70% by mass or less.

-Surfactant-
Since the content of the surfactant is adjusted so that the wetting energy of the clear ink with respect to the color ink layer is 40 mJ / m ² or more, it can be appropriately adjusted according to the type of the surfactant.
The surfactant preferably contains a polyether-modified siloxane compound.
By using the polyether-modified siloxane compound as a surfactant, the ink is hard to get wet with the ink-repellent layer of the nozzle plate of the ink head, the ejection failure due to the adhesion of the ink nozzle is prevented, and the ejection stability is improved.
The polyether-modified siloxane compound has the following general formula (I) from the viewpoints of not impairing dispersion stability depending on the type of coloring material and the combination of the organic solvent, low dynamic surface tension, permeability, and leveling property. It is preferably at least one selected from the compounds represented by (IV).

ただし、前記一般式（Ｉ）中、ｍは０～２３の整数を示し、ｎは１～１０の整数を示す。ａは１～２３の整数を示し、ｂは０～２３の整数を示す。Ｒは水素原子又は炭素数１～４のアルキル基を表す。

However, in the general formula (I), m represents an integer of 0 to 23, and n represents an integer of 1 to 10. a indicates an integer of 1 to 23, and b indicates an integer of 0 to 23. R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

ただし、前記一般式（ＩＩ）中、ｍは１～８の整数を示し、ｃ及びｄは１～１０の整数を示す。Ｒ_２及びＲ_３は、水素原子又は炭素数１～４のアルキル基を表す。

However, in the general formula (II), m indicates an integer of 1 to 8, and c and d indicate an integer of 1 to 10. R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

ただし、前記一般式（ＩＩＩ）中、ｅは１～８の整数を示し、Ｒ_４は水素原子又は炭素数１～４のアルキル基を表す。

However, in the general formula (III), e represents an integer of 1 to 8, and _R4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

ただし、前記一般式（ＩＶ）中、ｆは１～８の整数を示す。Ｒ_５は、下記一般式（Ａ）で表されるポリエーテル基を表す。

ただし、前記一般式（Ａ）中、ｇは０～２３の整数を示し、ｈは０～２３の整数を示し、ｇ及びｈが同時に０となることはない。Ｒ_６は、水素原子又は炭素数１～４のアルキル基を表す。

However, in the general formula (IV), f represents an integer of 1 to 8. R ₅ represents a polyether group represented by the following general formula (A).

However, in the general formula (A), g indicates an integer of 0 to 23, h indicates an integer of 0 to 23, and g and h do not become 0 at the same time. R ₆ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

As the polyether-modified siloxane compound, an appropriately synthesized compound may be used, or a commercially available product may be used.
The method for synthesizing the polyether-modified siloxane compound is not particularly limited and may be appropriately selected depending on the intended purpose. Can be referred to.
Specifically, it can be synthesized by subjecting (A) a polyether and (B) an organohydrogensiloxane to a hydrosilylation reaction.

The polyether of the component (A) indicates a polyoxyalkylene copolymer represented by-(Cn H _2n O)-(where _n is 2 to 4 in the formula).
The polyoxyalkylene copolymer unit is preferably an oxyethylene unit- (C ₂ H ₄ O)-, an oxypropylene unit- (C ₃ H ₆ O)-, an oxybutylene unit- (C ₄ H ₈ O)-,. Or they can include mixed units thereof.
The oxyalkylene unit may be arranged in any way and may form either a block or a random copolymer structure, but preferably forms a random copolymer group.
More preferably, the polyoxyalkylene contains both oxyethylene units (C ₂ H ₄ O) and oxypropylene units (C ₃ H ₆ O) in the random copolymer.

The organohydrogensiloxane of the component (B) is an organopolysiloxane containing at least one hydrogen-bonded hydrogen (SiH) per molecule.
Examples of the organopolysiloxane include (R ₃ SiO _0.5 ), (R ₂ SiO), (RSiO _1.5 ), (SiO ₂ ) (however, in the formula, R is an organic group or a hydrocarbon independently. Any number or combination of hydrocarbon units) (which is a hydrogen group) can be mentioned.
When R of (R ₃ SiO _0.5 ), (R ₂ SiO), and (RSiO _1.5 ) of the organopolysiloxane is a methyl group, the syroxy units are M, D, and T units, respectively. Shown, on the other hand, the (SiO ₂ ) siroxy unit is shown as the Q unit.
The organohydrogensiloxane has a similar structure but has at least one SiH present on the siroxy unit.
The methyl syloxy unit in the organohydrogensiloxane is " ^MH " syroxy unit (R ₂ HSiO _0.5 ), " ^DH " syroxy unit (RHSiO), "TH" ^syroxy unit (HSiO _1.5 ). Can be shown as including.
The organohydrogensiloxane may contain any number of M, ^MH , D, ^DH , T, TH, or Q ^syloxy units, provided that at least one syloxy unit contains SiH.

The component (A) and the component (B) are reacted by a hydrosilylation reaction.
The hydrosilylation reaction is not particularly limited and may be appropriately selected depending on the intended purpose, but it is preferably carried out by adding a hydrosilylation catalyst.
The hydrosilylation catalyst is not particularly limited and may be appropriately selected depending on the intended purpose. For example, platinum, rhodium, ruthenium, palladium, osmium, or iridium metal, or an organic metal compound thereof, or a combination thereof. And so on.
The content of the hydrosilylation catalyst is preferably 0.1 ppm or more and 1,000 ppm or less, and more preferably 1 ppm or more and 100 ppm or less, based on the masses of the component (A) and the component (B).
The hydrosilylation reaction can be carried out without dilution or in the presence of a solvent, but is preferably carried out in the presence of a solvent.

Examples of the solvent include alcohols (eg, methanol, ethanol, isopropanol, butanol, or n-propanol), ketones (eg, acetone, methyl ethyl ketone, or methyl isobutyl ketone); aromatic hydrocarbons (eg, benzene, toluene, etc.). Or xylene); aliphatic hydrocarbons (eg, heptane, hexane, or octane); glycol ethers (eg, propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol n-butyl ether, propylene glycol n-propyl ether, or ethylene. Glycol n-butyl ether), halogenated hydrocarbons (eg, dichloromethane, 1,1,1-trichloroethane, or methylene chloride, chloroform), dimethylsulfoxide, dimethylformamide, acetonitrile, tetrahydrofuran, volatile oils, mineral spirits, or naphtha. Can be mentioned. These may be used alone or in combination of two or more.

The amounts of the component (A) and the component (B) used in the hydrosilylation reaction are not particularly limited and can be appropriately adjusted according to the intended purpose, and can be appropriately adjusted with the total unsaturated group in the component (A). , Represented by the molar ratio of the component (B) to the SiH content.
It is preferable to use a polyether unsaturated group amount of 20 mol% or less with respect to the SiH molar amount of the organohydrogensiloxane, and it is more preferable to use a polyether unsaturated group amount of 10 mol% or less. preferable.
The hydrosilylation reaction is not particularly limited and can be carried out by any known batch method, semi-continuous method or continuous method, for example, a continuous method using a plug flow reactor.

Examples of commercially available products of the polyether-modified siloxane compound include 71ADDITIVE, 74ADDITIVE, 57ADDITIVE, 8029ADDITIVE, 8054ADDITIVE, 8211ADDITIVE, 8019ADDITIVE, 8526ADDITIVE, FZ-2123, and FZ-2191 (all manufactured by TORAY Dow Corning Co., Ltd.). , TSF4441, TSF4445, TSF4446, TSF4450, TSF4452, TSF4460 (all manufactured by Momentive Performance Materials); (Made by Nisshin Kagaku Kogyo Co., Ltd.); TEGO Wet KL245, 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-375, BYK-377 (all manufactured by Big Chemie Japan Co., Ltd.) and the like can be mentioned. These may be used alone or in combination of two or more. Among these, TEGO Wet 270 (manufactured by Evonik Industries) and Silface SAG503A (manufactured by Nisshin Kagaku Kogyo Co., Ltd.) are preferable.

As the surfactant, in addition to the above-mentioned polyether-modified siloxane compound, a fluorine-based surfactant, a silicone-based surfactant, an acetylene glycol, an acetylene alcohol-based surfactant, or the like may be used in combination.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Of these, those that do not decompose even at high pH are preferable. Examples of the silicone-based surfactant include side chain modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, single-ended modified polydimethylsiloxane, and side chain double-ended modified polydimethylsiloxane. Those having a polyoxyethylene group and a polyoxyethylene polyoxypropylene group as the modifying 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 compounds 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 ester compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. Polyoxyalkylene ether polymer compounds are particularly preferred because they have low foaming properties. 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. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain include a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a poly having a perfluoroalkyl ether group in the side chain. Examples thereof include salts of oxyalkylene ether polymers. The counter ions of the salts in these fluorine-based surfactants include Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , and NH (CH ₂ CH ₂ OH). ₃ etc. can be mentioned.

Examples of the amphoteric tenside include laurylaminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.

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 an acetylene alcohol.

Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, polyoxyethylene alkyl ether sulfate salt and the like.
These may be used alone or in combination of two or more. Among these, fluorine-based surfactants are preferable.

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 fluorosurfactant include a perfluoroalkyl phosphate ester compound, a perfluoroalkylethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain. Among these, the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is preferable because it has less 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.

上記一般式（Ｆ－１）で表される化合物において、水溶性を付与するためにｍは０～１０の整数が好ましく、ｎは０～４０の整数が好ましい。 [General formula (F-1)]

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 C _m F _{2 m + 1} and m is an integer of 1 to 6, or CH ₂ CH (OH) CH ₂ -C _m F _{2 m + 1} and m is An integer of 4 to 6 or an integer of CpH _{2p + 1} and p is an integer of 1 to 19. n is an integer of 1 to 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 DIC Corporation); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Chemours). , 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.) and the like. Among these, FS-3100, FS-34, FS-300, Neos Co., Ltd. manufactured by The Chemours Company, from the viewpoint of remarkably improving good print quality, especially color development, permeability to paper, wettability, and leveling property. FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by FT-110, Polyfox PF-151N manufactured by Omninova, and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferable.

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

-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.
Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 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-butanediol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3 -Pentanediol, petriol, etc. can be mentioned.
Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. ..
Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone. And so on.
Examples of the amides include formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide and the like.
Examples of amines include monoethanolamine, diethanolamine, triethylamine and the like.
Examples of the sulfur-containing compound include dimethyl sulfoxide, sulfolane, and thiodiethanol.
Examples of other organic solvents include propylene carbonate and ethylene carbonate.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or lower because it not only functions as a wetting agent but also has good drying properties.

As the organic solvent, a polyol compound having 8 or more carbon atoms and a glycol ether compound 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 the glycol ether compound 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; Examples thereof include polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

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

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

-water-
The water is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include ion-exchanged water, ultra-filtered water, reverse osmosis water, pure water such as distilled water, and ultrapure 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. % Or more and 60% by mass or less are more preferable.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected as needed, and examples thereof include antifoaming agents, pH adjusters, antiseptic and antifungal agents, and rust preventives.

－－Antifoaming agent －－
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.
Further, as the defoaming agent, a compound represented by the following general formula (a) is preferably used.

ただし、前記一般式（ａ）中、Ｒ_４及びＲ_５は、独立に炭素原子３～６個を有するアルキル基であり、Ｒ_６及びＲ_７は、独立に炭素原子１～２個を有するアルキル基であり、ｎは１～６の整数である。

However, in the general formula (a), R ₄ and R ₅ are alkyl groups having 3 to 6 carbon atoms independently, and R ₆ and R ₇ are alkyl groups having 1 to 2 carbon atoms independently. It is a group, and n is an integer of 1 to 6.

Examples of the compound represented by the general formula (a) include 2,4,7,9-tetramethyldecane-4,7-diol and 2,5,8,11-tetramethyldodecane-5,8-. Examples include diol.
Among these, 2,5,8,11-tetramethyldodecane-5,8-diol is preferable because of its antifoaming effect and high compatibility with clear ink.
The content of the defoaming agent is preferably 0.01% by mass or more and 10% by mass or less, and more preferably 0.1% by mass or more and 5% by mass or less with respect to the total amount of clear ink.

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

--anti-rust--
The rust preventive is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

--PH regulator ---
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.

<Manufacturing method of clear ink>
The clear ink is produced by dispersing or dissolving the organic solvent, the polymer particles, the surfactant, and if necessary, the other components in water, and stirring and mixing them.
The stirring and mixing can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, a stirrer using a stirring blade, a magnetic stirrer, a high-speed disperser, or the like.

-Clear ink physical characteristics-
The physical properties of the clear 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 clear ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, and 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 performance. Is more preferable. Here, for the viscosity, for example, a rotary viscometer (manufactured by Toki Sangyo Co., Ltd., RE-80L) 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 clear ink is preferably 35 mN / m or less, and 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 clear ink is preferably 7 to 12, more preferably 8 to 11, from the viewpoint of preventing corrosion of the metal member that comes into contact with the liquid.

<Color ink>
The color ink contains at least one coloring material, preferably contains an organic solvent, water, a surfactant, and polymer particles, and further contains other components as necessary.

-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. Further, a mixed crystal may be used as the pigment.
As the pigment, for example, black pigment, yellow pigment, magenta pigment, cyan pigment, white pigment, green pigment, orange pigment, glossy color pigment such as gold or silver, metallic pigment and the like can be used.
As inorganic pigments, carbon black produced by known methods such as contact method, furnace method, thermal method, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow. 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, acid 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, etc., 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 Carmin 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 Green 1, 4, 7, 8, 10, 17, 18, 36 and the like.

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 a dye, for example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52,80,82,249,254,289, C.I. I. Acid Blue 9,45,249, C.I. I. Acid Black 1,2,24,94, C.I. I. 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 and the like can be mentioned.

The content of the coloring material in the color ink is preferably 0.1% by mass or more and 15% by mass or less, preferably 1% by mass or more and 10% by mass or less, from the viewpoint of improving the image density, good fixing property, and ejection stability. Is more preferable.

As a method of dispersing the pigment to obtain an ink, a method of introducing a hydrophilic functional group into the pigment to obtain a self-dispersible 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, by adding a functional group such as a sulfone group or a carboxyl group to the pigment (for example, carbon), the pigment can be dispersed in water. The method 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-coated 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 effect of the present invention is not impaired. May be.
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low-molecular-weight dispersant and high-molecular-weight dispersant 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.
As the dispersant, RT-100 (nonionic surfactant) manufactured by Takemoto Oil & Fat Co., Ltd. and a naphthalene sulfonic acid Na formalin condensate can also be suitably used as the dispersant.
The dispersant may be used alone or in combination of two or more.

-Pigment dispersion-
It is possible to obtain an ink by mixing a material such as water or an organic solvent with the 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 cumulative 50% volume particle diameter (D ₅₀ ) of the pigment in the pigment dispersion is not particularly limited and may be appropriately selected depending on the intended purpose. However, the dispersion stability of the pigment becomes good, and the ejection stability and the image From the viewpoint of improving image quality such as density, it is preferably 10 nm or more and 200 nm or less, and more preferably 50 nm or more and 150 nm or less.
The cumulative 50% volume particle diameter ( _D50 ) of the pigment can be measured using, for example, a particle size distribution measuring device (Nanotrack UPA-EX150 manufactured by Nikkiso 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, but is 0.1% by mass from the viewpoint of obtaining good ejection stability and increasing the image density. 50% by mass or more is preferable, and 0.1% by mass or more and 30% by mass or less is more preferable.
It is preferable to degas the pigment dispersion by filtering the coarse particles with a filter, a centrifuge, or the like, if necessary.

-Polymer particles-
The types of polymer particles, the cumulative 50% volume particle diameter, and the like are the same as those of the polymer particles in the above clear ink.
The content of the polymer particles is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 8% by mass or less, based on the total amount of the color ink.

Since the water, surfactant, organic solvent, and other components in the color ink are the same as the water, surfactant, organic solvent, and other components in the clear ink, the description thereof will be omitted.

(Ink set)
The ink set of the present invention includes a color ink containing at least one color material and a clear ink containing at least polymer particles, and the clear ink is wetted with a color ink layer formed by the color ink. The energy is 40 mJ / m ² or more.

The color ink preferably contains at least one ink selected from cyan ink, magenta ink, yellow ink, and black ink.
As the color inks constituting the ink set, a plurality of inks having the same hue as the above color inks and having different pigment contents may be used.
Examples of the combination of the plurality of inks include, but are not limited to, inks having a black hue such as black, light black, gray, and light gray.

<Pretreatment liquid>
The pretreatment liquid contains a flocculant, an organic solvent, and water, and may contain a surfactant, an antifoaming agent, a pH adjuster, an antiseptic / antifungal agent, an anticorrosive agent, and the like, if necessary.
As the organic solvent, surfactant, defoaming agent, pH adjuster, antiseptic and antifungal agent, and rust preventive, the same materials as those used for ink can be used, and other materials used for known treatment liquids can be used. ..
The type of flocculant is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, and polyvalent metal salts.

<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, defoamers, pH adjusters, antiseptic and antifungal agents, rust preventives and the like, if necessary. Further, the post-treatment liquid may be applied to the entire recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

<Recording medium>
The recording medium is not particularly limited, and plain paper, glossy paper, special paper, cloth, or the like can be used, but good image formation is possible even if a non-permeable base material is used.
The non-permeable base material is a base material having a surface having a low water permeability and absorbability, and includes a material that does not open to the outside even if there are many cavities inside, and more quantitatively, A substrate having a water absorption of 10 mL / m ² or less from the start of contact to 30 msec ^1/2 in the Bristow method.
As the impermeable substrate, for example, a plastic film such as a vinyl chloride resin film, a polyethylene terephthalate (PET) film, a polypropylene film, a polyethylene film, or a polycarbonate film can be preferably used.

The recording medium is not limited to that used as a general recording medium, and wallpaper, flooring, 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.

<Printed matter>
The printed matter of the present invention is formed by forming a color ink layer on a recording medium and forming a clear ink layer on the color ink layer.
The arithmetic average roughness Ra in the printed matter is preferably 1.9 μm or less, more preferably 0.5 μm or more and 1.5 μm or less.
The arithmetic mean roughness Ra is _a value measured using a shape analysis laser microscope (VK-9510, manufactured by Keyence Corporation), and five arbitrary 100 μm × 100 μm regions were selected in the image region. Specific measurement conditions are lens magnification: 10 times, filter: none, Z measurement pitch: 0.5 μm, and measurement mode: surface shape.

The maximum difference in glossiness between colors in each printed matter formed by using each ink of the ink set is preferably 7 or less, and more preferably 5 or less.
The difference in glossiness between colors can be obtained by measuring the measurement of the 60 ° glossiness of each printed matter formed by using each ink of the ink set, and determining the value at which the difference in glossiness between the printed matter is maximized.

The glossiness was measured at an input / reflection angle of 60 degrees using a glossiness meter (micro-TRI-gloss, manufactured by BYK) in accordance with JIS (Japanese Industrial Standards) Z 8741. The higher the glossiness, the larger the value of the glossiness, and the unit is dimensionless.
Six images formed on A4 size paper were measured 5 times each in the transport direction of the printed matter and in the direction perpendicular to the transport direction, and the average gloss value measured 10 times in total was adopted. There was no difference between the glossiness in the transport direction and the glossiness in the direction perpendicular to the transport direction of the printed matter, and there was no difference in the glossiness in the in-plane direction of the solid image.

<Ink cartridge>
The ink cartridge used in the present invention comprises an ink contained in a container, and further has other members and the like appropriately selected as necessary.
The container is not particularly limited, and its shape, structure, size, material and the like can be appropriately selected according to the purpose.

(Printing method and printing equipment)
The printing apparatus of the present invention has a color ink applying means and a clear ink applying means, and further has other means as needed.

The printing method of the present invention includes a color ink applying step and a clear ink applying step, and further includes other steps as necessary.

-Color ink application process and color ink application means-
The color ink applying step is a step of applying a color ink containing at least one kind of coloring material to form a color ink layer, and is carried out by a color ink applying means.
The method for applying color ink is not particularly limited, and is an inkjet method, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, an air knife coating method, a comma coating method, and U. Comma coat method, AKKU coat method, smoothing coat method, micro gravure coat method, reverse roll coat method, 4-roll coat method, 5-roll coat method, dip coat method, curtain coat method, slide coat method, die coat method, etc. Can be mentioned. Among these, the inkjet method is preferably used.
The color ink applying means is not particularly limited, and examples thereof include an inkjet head.
It is preferable that at least a part of the liquid chamber portion, the fluid resistance portion, the diaphragm, and the nozzle member of the inkjet head is formed of a material containing at least one of silicon and nickel.
The nozzle diameter of the inkjet nozzle is preferably 30 μm or less, more preferably 1 μm or more and 20 μm or less.

-Clear ink applying process and clear ink applying means-
The clear ink applying step is a step of applying clear ink containing at least polymer particles on the color ink layer, and is carried out by the clear ink applying means.
The method for applying clear ink is not particularly limited, and is an inkjet method, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, an air knife coating method, a comma coating method, and U. Comma coat method, AKKU coat method, smoothing coat method, micro gravure coat method, reverse roll coat method, 4-roll coat method, 5-roll coat method, dip coat method, curtain coat method, slide coat method, die coat method, etc. Can be mentioned. Among these, the inkjet method is preferably used.
The clear ink applying means is not particularly limited, and examples thereof include an inkjet head.

The mode of ink flight is not particularly limited and differs depending on the type of the stimulus and the like. For example, when the stimulus is "heat", heat energy corresponding to the recording signal is applied to the ink in the recording head. For example, a method of applying the ink using a thermal head or the like, generating bubbles in the ink by the heat energy, and ejecting the ink as droplets from the nozzle hole of the recording head by the pressure of the bubbles can be mentioned. ..
When the stimulus is "pressure", for example, by applying a voltage to the piezoelectric element adhered to a position called a pressure chamber in the ink flow path in the recording head, the piezoelectric element bends and the volume of the pressure chamber is reduced. Then, a method of ejecting the ink as droplets from the nozzle hole of the recording head and the like can be mentioned.

<Recording device, recording method>
The color ink and clear ink used in 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 for 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, a pretreatment device, a device called a posttreatment device, and the like. ..
The recording device and the recording method may have 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 printed 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 three-dimensional images 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 book 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 mechanism portion 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, for example, an aluminum laminated film or the like. It is formed of packaging 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.
In the present invention, clear ink may be additionally used in addition to the above four types of ink. If additional ink is used, a liquid reservoir and liquid ejection head with the additional ink are added to the recording device.
On the other hand, a cartridge holder 404 is provided behind the opening when the cover 401c of the main body of the apparatus 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.

This recording device can include not only a portion for ejecting ink but also a device called a pretreatment device, a posttreatment device, and the like.
As one aspect of the pretreatment apparatus and the posttreatment apparatus, it has a pretreatment liquid and a posttreatment liquid as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y). There is an embodiment in which a liquid accommodating portion and a liquid discharge head are added, and a pretreatment liquid or a posttreatment liquid is discharged by an inkjet recording method.
As another aspect of the pretreatment device and the posttreatment device, there is a mode in which a pretreatment device and a posttreatment device by, for example, a blade coating method, a roll coating method, and a spray coating method are provided other than the inkjet recording method.

The uses of the color ink, clear ink, and ink set of the present invention are not particularly limited and can be appropriately selected according to the purpose, and can be applied to, for example, printed matter, paint, coating material, base material, and the like. Is. 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 stereoscopic image (three-dimensional model).
As the three-dimensional modeling apparatus for modeling the three-dimensional object, a known one can be used, and is not particularly limited, but for example, an apparatus 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. Further, 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. It is suitably used for molding after decorating the surface of electronic devices, meters of cameras, panels of operation parts, and the like.

Further, in the terms of the present invention, image formation, recording, printing, printing, etc. are all synonymous.
Recording media, media, and printed matter are all synonymous.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

(Preparation Example 1 of Pigment Dispersion Liquid)
<Preparation of resin-coated black pigment dispersion>
-Synthesis of polymer solution A-
After sufficient nitrogen gas replacement in a 1 L flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas introduction tube, a reflux tube, and a dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, and lauryl methacrylate 12. 0 g, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer, and 0.4 g of mercaptoethanol were mixed and heated to 65 ° C.
Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxylethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, and azobismethylvalero. A mixed solution of 2.4 g of nitrile and 18 g of methyl ethyl ketone was added dropwise into the flask over 2.5 hours. After the dropping, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobismethylvaleronitrile was added, and the mixture was further aged for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added into the flask to obtain 800 g of the polymer solution A having a concentration of 50% by mass.

-Preparation of pigment-containing polymer particle dispersion-
After sufficiently stirring 28 g of the above polymer solution A, 42 g of carbon black (FW100 manufactured by Degussa), 13.6 g of a 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 13.6 g of ion-exchanged water, a roll mill was used. Kneaded using. The obtained paste was put into 200 g of pure water, stirred sufficiently, and then methyl ethyl ketone and water were distilled off using an evaporator, and this dispersion was subjected to polyvinylidene flow having an average pore size of 5.0 μm in order to remove coarse particles. Pressure filtration was performed with a ride membrane filter to obtain a resin-coated black pigment dispersion liquid containing 15% by mass of carbon black and having a solid content concentration of 20% by mass.
The cumulative 50% particle diameter ( _D50 ) of the resin-coated black pigment particles in the obtained resin-coated black pigment dispersion was measured and found to be 104 nm.
The volume-based cumulative 50% particle size (D ₅₀ ) was measured using a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 2 of Pigment Dispersion Liquid)
<Preparation of resin-coated cyan pigment dispersion>
Resin-coated cyan pigment dispersion in the same manner as in Preparation Example 1 of the pigment dispersion, except that carbon black was changed to a phthalocyanine pigment (CI Pigment Blue 15: 3) in Preparation Example 1 of the pigment dispersion. Was prepared.
The cumulative 50% particle diameter (D ₅₀ ) of the resin-coated cyan pigment particles in the obtained resin-coated cyan pigment dispersion was 93 nm as a result of measuring in the same manner as in Preparation Example 1 of the pigment dispersion. ..

(Preparation Example 3 of Pigment Dispersion Liquid)
<Preparation of resin-coated magenta pigment dispersion>
A resin-coated magenta pigment dispersion was prepared in the same manner as in Preparation Example 1 of the pigment dispersion except that carbon black was changed to a magenta pigment (CI Pigment Red 122) in Preparation Example 1 of the pigment dispersion. did.
The cumulative 50% particle diameter ( _D50 ) of the resin-coated magenta pigment particles in the obtained resin-coated magenta pigment dispersion based on the volume was measured in the same manner as in Preparation Example 1 of the pigment dispersion, and the result was 127 nm. ..

(Preparation Example 4 of Pigment Dispersion Liquid)
<Preparation of resin-coated yellow pigment dispersion>
In Preparation Example 1 of the pigment dispersion liquid, carbon black is used as a monoazo yellow pigment (CI.
A resin-coated yellow pigment dispersion was prepared in the same manner as in Preparation Example 1 of the pigment dispersion except that the pigment was changed to Pigment Yellow 74).
The cumulative 50% particle diameter ( _D50 ) of the resin-coated yellow pigment particles in the obtained resin-coated yellow pigment dispersion based on the volume was measured in the same manner as in Preparation Example 1 of the pigment dispersion, and the result was 76 nm. ..

(Manufacturing example 1 of color ink)
-Making color ink 1-
After premixing the mixture of the following formulation, filter with a needleless syringe with a capacity of 25 mL equipped with a filter (acetyl cellulose membrane, outer diameter 2.5 cm, manufactured by Fuji Film Co., Ltd.) with an average pore size of 5.0 μm, and coarse particles. Was removed to obtain color ink 1.
[Prescription of color ink 1]
-The resin-coated black pigment dispersion: 4.0% by mass
-TOCRYL W-6109 (acrylic resin emulsion, manufactured by Toyochem Co., Ltd.): 3.0% by mass (converted to resin amount)
-Takelac W-6110 (urethane resin emulsion, manufactured by Mitsui Chemicals, Inc.): 3.0% by mass (converted to resin amount)
-3-Methyl-3-methoxybutanol: 4.0% by mass
-3-Methyl-1,3-butanediol: 4.0% by mass
・ 1,2-Propanediol: 20% by mass
-2-Ethyl-1,3-hexanediol: 1.5% by mass
-TEGO WET-270 (polyether modified siloxane copolymer, manufactured by Evonik): 1.0% by mass
-Proxel GXL (antifungal agent, manufactured by Abyssia): 0.05% by mass
-2,4,7,9-Tetramethyldecane-4,7-diol: 0.4% by mass
-2-Amino-2-ethyl-1,3-propanediol: 0.3% by mass
-Pure water: remaining amount (total: 100% by mass)

(Manufacturing examples 2 to 11 of color ink)
-Making color inks 2 to 11-
Color inks 2 to 11 were prepared in the same manner as in Production Example 1 of color ink, except that the formulations shown in Tables 1 and 2 below were changed in Production Example 1 of color ink. Regarding the resin, the amount of the added resin is described.

Next, for each of the obtained color inks, the static surface tension was measured by the Wilhelmy method (plate method, vertical plate method) in the same manner as in the above <method for determining the surface tension of the liquid>. The results are shown in Tables 1 and 2.

(Manufacturing example of clear ink 1)
-Making clear ink 1-
After premixing the mixture of the following formulations, filter with a needleless syringe with a capacity of 25 mL equipped with a filter (acetyl cellulose membrane, outer diameter 2.5 cm, manufactured by Fuji Film Co., Ltd.) with an average pore size of 5.0 μm, and coarse-grained. Clear ink 1 was obtained by removing the particles.
[Prescription of clear ink 1]
-TOCRYL W-6109 (acrylic resin emulsion, manufactured by Toyochem Co., Ltd.): 15% by mass (converted to resin amount)
-3-Methyl-3-methoxybutanol: 4.0% by mass
-3-Methyl-1,3-butanediol: 4.0% by mass
・ 1,2-Propanediol: 20% by mass
-2-Ethyl-1,3-hexanediol: 1.5% by mass
-TEGO WET-270 (polyether modified siloxane copolymer, manufactured by Evonik): 1.0% by mass
-Proxel GXL (antifungal agent, manufactured by Abyssia): 0.05% by mass
-2,4,7,9-Tetramethyldecane-4,7-diol: 0.4% by mass
-2-Amino-2-ethyl-1,3-propanediol: 0.3% by mass
-Pure water: remaining amount (total: 100% by mass)

(Manufacturing examples 2 to 3 of clear ink)
-Making clear inks 2-3-
In Clear Ink Production Example 1, clear inks 2 to 3 were prepared in the same manner as in Clear Ink Production Example 1 except that the clear ink formulations shown in Table 3 were changed. Regarding the resin, the amount of the added resin is described.

<Measurement of static surface tension>
Next, for each of the obtained clear inks, the static surface tension was measured in the same manner as in the above <How to obtain the static surface tension of the liquid>. The results are shown in Table 3.

Details of each component in the color inks and clear inks shown in Tables 1 to 3 are as follows.

-resin-
TOCRYL W-6109: Acrylic resin emulsion (cumulative 50% volume particle diameter (D ₅₀ ) 80 nm, solid content concentration 41.1% by mass, manufactured by Toyochem Co., Ltd.)
TOCRYL W-4568: Acrylic resin emulsion (cumulative 50% volume particle diameter (D ₅₀ ) 103 nm, solid content concentration 40.1% by mass, manufactured by Toyochem Co., Ltd.)
TOCRYL W-4657: Acrylic resin emulsion (cumulative 50% volume particle diameter (D ₅₀ ) 53 nm, solid content concentration 40.3 mass%, manufactured by Toyochem Co., Ltd.)
Takelac W-6110: Urethane resin emulsion (cumulative 50% particle size (D ₅₀ ) 47 nm, solid content concentration 30.9 mass%, manufactured by Mitsui Chemicals, Inc.)

-Surfactant-
-TEGO WET-270: Polyether-modified siloxane copolymer (manufactured by Evonik)
-Silface SAG503A: Polyether-modified siloxane compound (manufactured by Nissin Chemical Industry Co., Ltd.)
-TRITON (registered trademark) HW-1000: Polyoxyethylene alkyl ether (manufactured by Dow Chemical Co., Ltd.)

-Antifungal agent-
・ Proxel GXL (manufactured by Abyssia)

(Examples 1 to 3 and Comparative Examples 1 to 3)
<Color image formation>
For the image formation of the color ink, IPSiO GX e5500 (manufactured by Ricoh Co., Ltd.) was used under the environmental conditions of 23 ° C. ± 0.5 ° C. and 50 ± 5% RH based on the description in Table 5. In advance, a single color 5 cm x 20 cm rectangular solid image is printed on Super Fine paper (manufactured by Epson Corporation), which is an inkjet paper, with a resolution of 1,200 dpi and an ink adhesion amount of 0.96 mg / cm ² (600 mg / A4 size). ) Was varied in the drive voltage of the piezo element to print, and the amount of ink adhered was adjusted. At this time, each color ink of each color was individually set so that the amount of ink adhered was the same. The amount of ink adhered can be obtained by measuring the mass of the Super Fine paper before and after printing the rectangular solid image. As the print mode, "Paper type: Glossy paper", "Print quality: Beautiful", and "Color matching: No" were selected according to the user settings of the driver attached to the printer.
Next, under the conditions set above, a coated paper (OK top coat +, basis weight: 127.9 gsm, manufactured by Oji Paper Co., Ltd.) was set, and a set of 4 colors created by Microsoft Word 2016 (manufactured by Microsoft) was used. As shown in FIG. 7, a solid image is printed as a single image at a resolution of 1,200 dpi, and then placed in a constant temperature bath set to an internal temperature of 90 ° C. for 30 seconds. It was dry.
The arithmetic mean roughness of the color ink image printed on coated paper (OK top coat +, basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.): Ra was 1.50 μm to 1.65 μm.
The arithmetic mean roughness Ra was measured using a shape analysis laser microscope (VK-9510, manufactured by KEYENCE CORPORATION) at a magnification of 50. The average value when 5 points were measured for the same sample was adopted as the value of Ra. Specific measurement conditions are lens magnification: 10 times, filter: none, Z measurement pitch: 0.5 μm, and measurement mode: surface shape.

Next, the dispersion component γ _S ^d and the polar component γ _SP of the surface free energy of the surface free energy of each color ink layer are measured as ^follows , and the maximum difference of the dispersion component γ _s ^d between the layers of each color ink is determined. And the maximum difference of the ^polar component γ _sp between the layers of each color ink was determined. The results are shown in Table 4.

< ^Measurement of dispersion component γ _S ^d and polar component γ _SP of surface free energy of color ink layer>
For the printed matter after drying, two kinds of liquids (pure water and methylene iodide) whose surface free energy values are known are used, and the printed matter is contacted in the same manner as the above <method for obtaining the contact angle θ of the clear ink>. The angle is measured, and the dispersion component γ _S ^d and the polar component γ SP of the surface free energy of each color ink layer are obtained from the _Fowkes ^- Owens model, and the maximum difference of the dispersion component γ _s ^d between the layers of each color ink and the maximum difference of the dispersion component γ s d between the layers of each color ink. The maximum difference in the ^polar component γ _sp was calculated.

<Formation of clear ink image>
Next, according to the combinations shown in Table 5, each clear ink produced in Production Examples 1 to 3 of clear ink was printed on each of the above color ink layers. For the image formation of the clear ink, IPSiO GX e5500 (manufactured by Ricoh Co., Ltd.) was used under environmental conditions of 25 ° C. ± 0.5 ° C. and 50 ± 5% RH. The clear ink layer was printed on a solid image chart created by Microsoft Word 2016 (manufactured by Microsoft) at a resolution of 600 dpi, and then dried in a constant temperature bath set to an internal temperature of 1000 ° C. for 120 seconds. The amount of clear ink adhered was adjusted to 0.80 mg / cm ² (500 mg / A4 size) by the same method as the amount of adhered color ink. As the print mode, "Paper type: Plain paper", "Print quality: Beautiful", and "Color matching: No" were selected from the user settings of the driver attached to the printer. After forming clear ink on the surface of a solid image of color ink formed on coated paper (OK top coat +, basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.) as a recording medium, the inside It was dried for 120 seconds in a constant temperature bath set to a temperature of 100 ° C. The color image at this time is the image shown in FIG. 7 described above.

Next, the wet energy Wa for the color ink layer of the clear ink was obtained as follows. The results are shown in Table 5.

<Calculation of wet energy Wa>
With the combinations shown in Table 5, clear ink was dropped on the color solid image, and the contact angle θ of the clear ink with respect to the color ink layer was measured in the same manner as described above. On the other hand, the static surface tension γ _L of the clear ink was measured in the same manner as above. From these results, the wetting energy Wa was obtained by the Young-Dupre formula represented by the following formula (3).

Next, for each of the obtained images, the 60 ° glossiness and the arithmetic mean roughness Ra were evaluated as follows. In addition, the ejection stability of each clear ink was evaluated as follows. The results are shown in Table 5.

<Measurement of 60 ° gloss>
The glossiness was measured at an input / reflection angle of 60 degrees using a glossiness meter (micro-TRI-gloss, manufactured by BYK) in accordance with JIS (Japanese Industrial Standards) Z 8741. The higher the glossiness, the larger the value of the glossiness, and the unit is dimensionless.
Six images formed on A4 size paper were measured 5 times each in the transport direction of the printed matter and in the direction perpendicular to the transport direction, and the average gloss value measured 10 times in total was adopted. There was no difference between the glossiness in the transport direction and the glossiness in the direction perpendicular to the transport direction of the printed matter, and there was no difference in the glossiness in the in-plane direction of the solid image.

<Measurement of Arithmetic Mean Roughness Ra>
Each of the obtained images was a value measured using a shape analysis laser microscope (VK-9510, manufactured by KEYENCE CORPORATION), and five arbitrary 100 μm × 100 μm regions were selected in the image region. The average value of these was calculated and used as the arithmetic mean roughness Ra. Specific measurement conditions are lens magnification: 10 times, filter: none, Z measurement pitch: 0.5 μm, and measurement mode: surface shape. The smaller the arithmetic mean roughness Ra, the higher the surface smoothness of the image.

<Clear ink ejection stability (intermittent ejection evaluation)>
For each of the obtained clear inks, a solid image created by Microsoft Word 2016 (manufactured by Microsoft) and arranged so as to have an area ratio of 5% on A4 size paper is coated with coated paper (OK top coat +, basis weight:). 200 sheets were continuously punched into 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.), and the ejection turbulence of each nozzle after the punching was visually observed and evaluated according to the following criteria. In addition, B or more is a level that can be actually used.
The print mode used was a driver attached to the printer, which was modified from the user settings for plain paper to "glossy paper-clean" mode and "no color correction".
[Evaluation criteria]
A: No discharge turbulence B: Slight discharge turbulence C: There is discharge turbulence or there is a part that does not discharge

From the results of Tables 4 and 5, in Examples 1 to 3, compared with Comparative Examples 1 to 3, the printed matter having excellent gloss uniformity between the color ink layers of each color, high surface smoothness, and excellent gloss is obtained. It turned out to be obtained.

ただし、前記一般式（Ｉ）中、ｍは０～２３の整数を示し、ｎは１～１０の整数を示す。ａは１～２３の整数を示し、ｂは０～２３の整数を示す。Ｒは水素原子又は炭素数１～４のアルキル基を表す。
＜８＞ 前記カラーインク及び前記クリアインクの２５℃での静的表面張力が、２０ｍＮ／ｍ以上３５ｍＮ／ｍ以下である、前記＜１＞から＜７＞のいずれかに記載の印刷装置である。
＜９＞ インクジェット用である前記＜１＞から＜８＞のいずれかに記載の印刷装置である。
＜１０＞ 記録媒体上に少なくとも１種の色材を含有するカラーインクを付与してカラーインク層を形成するカラーインク付与工程と、
前記カラーインク層上に少なくともポリマー粒子を含有するクリアインクを付与するクリアインク付与工程と、を含み、
前記クリアインクは、前記カラーインク層に対する濡れエネルギーが４０ｍＪ／ｍ^２以上であることを特徴とする印刷方法である。
＜１１＞ 少なくとも１種の色材を含有するカラーインクと、
少なくともポリマー粒子を含有するクリアインクと、を有し、
前記クリアインクは、前記カラーインクによって形成したカラーインク層に対する濡れエネルギーが４０ｍＪ／ｍ^２以上であることを特徴とするインクセットである。 Examples of aspects of the present invention are as follows.
<1> A color ink applying means for forming a color ink layer by applying a color ink containing at least one kind of color material on a recording medium.
It has a clear ink applying means for applying a clear ink containing at least polymer particles on the color ink layer.
The clear ink is a printing apparatus characterized in that the wetting energy for the color ink layer is 40 mJ / m ² or more.
<2> The printing apparatus according to <1>, wherein the clear ink has a wetting energy of 40 mJ / m ² or more and 65 mJ / m ² or less with respect to the color ink layer.
<3> The color ink has at least black ink, yellow ink, magenta ink, and cyan ink.
Assuming that the dispersion component of the surface free energy of the color ink layer of each color formed by the color ink is γ _s ^d and the polar component of the surface free energy of the color ink layer of each color is γ _s ^p , the dispersion between the color ink layers of each color is assumed. The maximum difference of the component γ _s ^d is 0.3 mJ / m ² or more, and the maximum difference of the polar component γ _s ^p in the color ink layer of each color is 5 mJ / m ² or less. The printing apparatus according to any one.
<4> The printing apparatus according to any one of <1> to <3>, wherein the content of the polymer particles is 10% by mass or more and 20% by mass or less.
<5> The printing apparatus according to any one of <1> to <4>, wherein the cumulative 50% volume particle diameter (D ₅₀ ) of the polymer particles is 50 nm or more and 100 nm or less.
<6> The printing apparatus according to any one of <1> to <5>, wherein the clear ink contains a surfactant.
<7> The printing apparatus according to <6>, wherein the surfactant is a polyether-modified siloxane compound represented by the following general formula (I).

However, in the general formula (I), m represents an integer of 0 to 23, and n represents an integer of 1 to 10. a indicates an integer of 1 to 23, and b indicates an integer of 0 to 23. R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
<8> The printing apparatus according to any one of <1> to <7>, wherein the static surface tension of the color ink and the clear ink at 25 ° C. is 20 mN / m or more and 35 mN / m or less. ..
<9> The printing apparatus according to any one of <1> to <8> for inkjet.
<10> A color ink applying step of applying a color ink containing at least one kind of color material on a recording medium to form a color ink layer, and a process of applying the color ink.
A clear ink applying step of applying a clear ink containing at least polymer particles on the color ink layer is included.
The clear ink is a printing method characterized in that the wetting energy for the color ink layer is 40 mJ / m ² or more.
<11> A color ink containing at least one color material and
With, with, at least a clear ink containing polymer particles,
The clear ink is an ink set characterized in that the wetting energy for the color ink layer formed by the color ink is 40 mJ / m ² or more.

According to the printing apparatus according to any one of <1> to <9>, the printing method according to <10>, and the ink set according to <11>, the conventional problems are solved and the present invention is made. Can achieve the purpose of.

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 Patent No. 4096158 Japanese Unexamined Patent Publication No. 2004-306557 Japanese Patent No. 5509603

Claims (11)

A color ink applying means for forming a color ink layer by applying a color ink containing at least one kind of color material on a recording medium.
It has a clear ink applying means for applying a clear ink containing at least polymer particles on the color ink layer.
The clear ink is a printing apparatus having a wetting energy of 40 mJ / m ² or more with respect to the color ink layer. The printing apparatus according to claim 1, wherein the clear ink has a wetting energy with respect to the color ink layer of 40 mJ / m ² or more and 65 mJ / m ² or less. The color ink has at least black ink, yellow ink, magenta ink, and cyan ink.
Assuming that the dispersion component of the surface free energy of the color ink layer of each color formed by the color ink is γ _s ^d and the polar component of the surface free energy of the color ink layer of each color is γ _s ^p , the dispersion between the color ink layers of each color is assumed. According to any one of claims 1 to 2, the maximum difference of the component γ _s ^d is 0.3 mJ / m ² or more, and the maximum difference of the polar component γ _s ^p in the color ink layer of each color is 5 mJ / m ² or less. The printing device described. The printing apparatus according to any one of claims 1 to 3, wherein the content of the polymer particles is 10% by mass or more and 20% by mass or less. The printing apparatus according to any one of claims 1 to 4, wherein the cumulative 50% volume particle diameter (D ₅₀ ) of the polymer particles is 50 nm or more and 100 nm or less. The printing apparatus according to any one of claims 1 to 5, wherein the clear ink contains a surfactant. The printing apparatus according to claim 6, wherein the surfactant is a polyether-modified siloxane compound represented by the following general formula (I).

However, in the general formula (I), m represents an integer of 0 to 23, and n represents an integer of 1 to 10. a indicates an integer of 1 to 23, and b indicates an integer of 0 to 23. R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The printing apparatus according to any one of claims 1 to 7, wherein the static surface tension of the color ink and the clear ink at 25 ° C. is 20 mN / m or more and 35 mN / m or less. The printing apparatus according to any one of claims 1 to 8, which is for inkjet. A color ink applying step of applying a color ink containing at least one kind of color material on a recording medium to form a color ink layer, and a color ink applying step.
A clear ink applying step of applying a clear ink containing at least polymer particles on the color ink layer is included.
The clear ink is a printing method characterized in that the wetting energy for the color ink layer is 40 mJ / m ² or more. Color inks containing at least one colorant,
With, with, at least a clear ink containing polymer particles,
The clear ink is an ink set characterized in that the wetting energy for the color ink layer formed by the color ink is 40 mJ / m ² or more.

Images