JP6896530B2 - Inkjet recording method and inkjet recording device - Google Patents

Description

The present invention relates to an inkjet recording method and an inkjet recording device.

In the inkjet recording method, an image is formed by directly or indirectly applying a liquid composition (ink) containing a coloring material onto a recording medium such as paper. At this time, curling or cockling may occur due to excessive absorption of the liquid component in the ink by the recording medium.

Therefore, in order to quickly remove the liquid component in the ink, a method of drying the recording medium by means such as infrared rays or a method of forming an image on the transfer body and then removing the liquid component contained in the image on the transfer body. There is a method of transferring an image to a recording medium such as paper after drying with heat energy or the like.

Further, as a means for removing the liquid component contained in the image on the transfer body, a method in which a roller-shaped porous body is brought into contact with the ink image to absorb and remove the liquid component from the ink image without using thermal energy. Have been proposed (Patent Documents 1 to 3).

JP-A-2009-45551 Japanese Unexamined Patent Publication No. 2001-179959 Japanese Unexamined Patent Publication No. 2005-271401

According to the studies by the present inventors, it has been found that the method for removing the solvent described in Patent Documents 1 to 3 may cause the coloring material to adhere to the porous body used for removing the solvent.

Patent Document 1 describes a metal porous body that is arranged so as to be in contact with the recording surface to remove the solvent on the recording surface. Patent Document 2 describes a liquid solvent absorber that absorbs the liquid solvent of the ink, covers at least a part of the surface of the liquid solvent absorber, has releasability from the colorant of the ink, and is a liquid of the ink. An ink absorber having a release member that transmits a medium is described. In Patent Document 3, the surface of the ink that comes into contact with the excess liquid is hydrophilic, and the hydrophilic surface has an absorber having a recovery rate of 90% or more when fine particles having an average particle size of 5 μm are filtered. The liquid absorbing means to have is described.

However, it cannot be said that the porous bodies and absorbers described in Patent Documents 1 to 3 have both suppression of colorant adhesion and absorption of liquid components of ink at a high level, and further improvement is required. It turned out that there was.

Therefore, an object of the present invention is to provide an inkjet recording method and an inkjet recording apparatus capable of both suppressing adhesion of a coloring material and absorbing liquid components contained in an image at a high level.

The above object is achieved by the following invention.

That is, in the inkjet recording method according to the present invention, an ink containing a color material and a reaction liquid that agglomerates the color material are applied to a discharge medium, and a liquid component and an agglomerate containing the color material are applied. And the process of forming an ink image with
A step of bringing the first surface of the porous body of the liquid absorbing member into contact with the ink image on the ejected medium to remove at least a part of the liquid component from the ink image.
It is an inkjet recording method having
The porous body has a hydrophilic porous layer and a water-repellent porous layer on the hydrophilic porous layer.
The first surface is the surface on the side where the water-repellent porous layer is present.
The average pore diameter of the water-repellent porous layer is equal to or greater than the average pore diameter of the hydrophilic porous layer and equal to or less than the dot diameter of the agglomerates formed by one drop of ink droplets of the agglomerates. And
The thickness of the water-repellent porous layer is T (μm), the porosity of the water-repellent porous layer is A (%), and the thickness of the agglomerates formed by the single drop of ink is D (μm). When the ratio of the liquid component of the agglomerate formed by the one drop of ink is P (%), the T, the A, the D, and the P satisfy the relationship of the following formula (1). And.
T <D × P / A formula (1)

Further, the inkjet recording apparatus according to the present invention includes a ejected medium and
A reaction liquid applying device that applies a reaction liquid that agglutinates the coloring material contained in the ink onto the ejection medium, and
An ink application device having an inkjet head that ejects ink containing a coloring material onto the ejected medium, and an ink applying device.
A liquid having a porous body that comes into contact with the reaction liquid and an ink image having an agglomerate containing a liquid component and a coloring material formed by the ink and absorbs at least a part of the liquid component from the ink image. Absorbent member and
Inkjet recording device with
The porous body has a hydrophilic porous layer and a water-repellent porous layer on the hydrophilic porous layer.
The liquid absorbing member is arranged so that the first surface of the porous body in contact with the ink image is the surface on the side where the water-repellent porous layer exists.
The average pore diameter of the water-repellent porous layer is equal to or greater than the average pore diameter of the hydrophilic porous layer and equal to or less than the dot diameter of the agglomerates formed by one drop of ink droplets of the agglomerates. And
The thickness of the water-repellent porous layer is T (μm), the porosity of the water-repellent porous layer is A (%), and the thickness of the agglomerates formed by the single drop of ink is D (μm). When the ratio of the liquid component of the agglomerate formed by the one drop of ink is P (%), the T, the A, the D, and the P satisfy the relationship of the following formula (1). And.
T <D × P / A formula (1)

According to the present invention, it is possible to provide an inkjet recording method and an inkjet recording apparatus capable of both suppressing adhesion of a coloring material and absorbing liquid components contained in an image at a high level.

It is a schematic diagram which shows the state when the porous body which concerns on this invention comes into contact with an ink image. It is a schematic diagram which enlarged the cross section near the surface of the porous body when the porous body which concerns on this invention comes into contact with an ink image. It is a schematic diagram which shows an example of the structure of the transfer type inkjet recording apparatus in one Embodiment of this invention. It is a schematic diagram which shows an example of the structure of the direct drawing type inkjet recording apparatus in one Embodiment of this invention. It is a block diagram which shows the control system of the whole apparatus in the inkjet recording apparatus shown in FIGS. It is a block diagram of the printer control part in the transfer type inkjet recording apparatus shown in FIG. It is a block diagram of the printer control part in the direct drawing type inkjet recording apparatus shown in FIG.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

In the present invention, when the compound is a salt, the salt is dissociated into ions and exists in the ink, but for convenience, it is expressed as "containing a salt". Further, the ink for inkjet may be simply referred to as "ink". Unless otherwise specified, the physical property values are values at normal temperature (25 ° C.) and normal pressure (1 atm).

The present inventors have diligently studied a method for removing a liquid component contained in an ink image by bringing a porous body into contact with the ink image. As a result, the present inventors suppress the adhesion of the coloring material and the liquid component contained in the image by satisfying a specific relationship between the physical characteristics of the agglomerates formed by the ink and the reaction liquid and the physical characteristics of the porous body. We have found that it is possible to achieve both high levels of absorbency, and have arrived at the present invention. The mechanism by which the effect of the present invention is obtained has not been clarified at present, but the present inventors speculate as follows.

FIG. 1 is a schematic view showing a state when the porous body of the liquid absorbing member comes into contact with the ink image. The roller-shaped porous body 1 has a water-repellent porous layer 2 and a hydrophilic porous layer 3. Then, by contacting the ink image 4 formed on the ejected medium 5 such as a transfer body or a recording medium that temporarily holds the ink image, the porous body 1 removes the liquid component contained in the ink image 4. By absorbing, the liquid component is removed from the ink image.

FIG. 2 is a schematic view of an enlarged cross section of the vicinity of the surface of the porous body when the porous body comes into contact with the ink image. Note that FIG. 2 shows the pores of the hydrophilic porous layer and the hydrophobic porous layer as images of capillaries in order to show how the capillary force is generated, and is not necessarily the actual form.

When the ink comes into contact with the reaction liquid applied to the ejection medium, the dispersibility of the coloring material (pigment) contained in the ink is lowered, and the coloring material is aggregated. An ink image is formed by the agglomerates containing this coloring material. The ink contains a liquid component (mainly water) in addition to the coloring material. Further, the reaction solution may also contain a liquid component. The liquid components contained in the ink and the reaction liquid are also contained in the ink image. Then, in order to remove the liquid component 6 contained in the ink image, the porous body has a hydrophilic porous layer 3. However, since the hydrophilic porous layer easily absorbs agglomerates containing a coloring material as well as a liquid component, the coloring material tends to adhere to the porous body. In response to this problem, in the porous body according to the present invention, the water-repellent porous layer 2 is formed on the hydrophilic porous layer 3. Further, even when the water-repellent porous layer 2 is formed, the liquid component 6 reaches the position of the pores of the hydrophilic porous layer 3, and the hydrophilic porous layer 3 holds the liquid component 6. The present inventors examined the composition for absorption. As a result, the average pore diameter of the water-repellent porous body is equal to or larger than the average pore diameter of the hydrophilic porous body and equal to or smaller than the dot diameter of the agglomerates, and the relationship of the following formula (1). We have found that it is important to meet.
T <D × P / A formula (1)

In this formula (1), T is the thickness of the water-repellent porous layer (μm), A is the porosity (%) of the water-repellent porous layer, and D is the thickness of the agglomerate formed by one drop of ink. (Μm), P is the proportion (%) of the liquid component of the agglomerate formed by one drop of ink.

When the average pore size of the water-repellent porous body is equal to or larger than the average pore size of the hydrophilic porous body, the porous body is in contact with the agglomerate (particularly, in contact with pressure). The liquid component contained in the water-repellent porous layer easily passes through the pores of the water-repellent porous layer. As a result, the capillary force of the pores in the hydrophilic porous layer facilitates absorption of the liquid. Further, if the average pore diameter of the water-repellent porous layer is equal to or smaller than the dot diameter of the agglomerates formed by one drop of ink, the liquid can be absorbed even from a single dot.

Further, when the thickness T of the water-repellent porous layer of the porous body satisfying the above formula (1), the liquid component of the ink image easily passes through the water-repellent porous layer, and the ink image becomes hydrophilic. The capillary force of the pores in the porous layer facilitates absorption of liquid.

In the formula (1), the thickness D of the agglomerate formed by one drop of ink is the thickness of the ink droplet that has landed on the ejected medium. The thickness of a single dot corresponds to the height of a cylinder having a circle formed by the dot diameter of the droplet as the bottom surface. When droplets such as a solid printing portion are connected, it corresponds to the recording density of printing dots, and when printing one droplet per pixel, the value obtained by dividing the droplet volume by the area of one pixel is the thickness. The dot diameter of the ink droplet is N = 1.6 to 2.0 when the magnification of the formed dot diameter is expressed as the bleeding rate N with respect to the ink ejection droplet diameter.

In the formula (1), the ratio P of the liquid component before the liquid absorption of the agglomerate can be obtained from the ratio of the liquid component such as water or organic solvent contained in the ink and the reaction liquid.

The inkjet recording apparatus according to the embodiment of the present invention will be described below with reference to the drawings.

In the inkjet recording apparatus of the present embodiment, ink is ejected onto a transfer body as an ejection medium to form an ink image, and the ink image after liquid absorption from the ink image by the liquid absorbing member is transferred to the recording medium. Examples thereof include an inkjet recording device and an inkjet recording device that forms an ink image on a recording medium such as paper or cloth as a discharge medium and absorbs liquid from the ink image on the recording medium by a liquid absorbing member. In the present invention, the former inkjet recording device is hereinafter referred to as a transfer type inkjet recording device for convenience, and the latter inkjet recording device is hereinafter referred to as a direct drawing type inkjet recording device for convenience.

Each inkjet recording device will be described below.

(Transfer type inkjet recording device)
FIG. 3 is a schematic view showing an example of a schematic configuration of the transfer type inkjet recording apparatus 100 of the present embodiment. This recording device is a single-wafer inkjet recording device that produces a recorded material by transferring an ink image to a recording medium 108 via a transfer body 101. In the present embodiment, the X direction, the Y direction, and the Z direction indicate the width direction (total length direction), the depth direction, and the height direction of the inkjet recording apparatus 100, respectively. The recording medium P is conveyed in the X direction.

As shown in FIG. 3, the transfer type inkjet recording device 100 of the present invention is a reaction liquid applying device 103 that applies a transfer body 101 supported by a support member 102 and a reaction liquid that reacts with color ink on the transfer body 101. An ink application device 104 equipped with an inkjet head that applies colored ink onto the transfer body 101 to which the reaction solution is applied and forms an ink image that is an image of the ink on the transfer body, and an ink application device 104 on the transfer body. It has a liquid absorbing device 105 that absorbs a liquid component from an ink image, and a transfer pressing member 106 for transferring an ink image on a transfer body from which the liquid component has been removed onto a recording medium 108 such as paper. Further, the transfer type inkjet recording apparatus 100 may have a transfer body cleaning member 109 that cleans the surface of the transfer body 101 after transfer, if necessary. As a matter of course, the transfer body 101, the reaction liquid application device 103, the inkjet head of the ink application device 104, the liquid absorption device 105, and the transfer body cleaning member 109 each correspond to the recording medium 108 used in the Y direction. Has a length of

The transfer body 101 rotates about the rotation axis 102a of the support member 102 in the direction of arrow A in FIG. The rotation of the support member 102 causes the transfer body 101 to move. The reaction solution and the ink are sequentially applied by the reaction solution applying device 103 to the moving transfer body 101, and an ink image is formed on the transfer body 101. The ink image formed on the transfer body 101 is moved to a position where it comes into contact with the liquid absorption member 105a of the liquid absorption device 105 by the movement of the transfer body 101.

The transfer body 101 and the liquid absorbing device 105 move in synchronization with the rotation of the transfer body 101. The ink image formed on the transfer body 101 goes through a state of being in contact with the moving liquid absorbing member 105a. During this time, the liquid absorbing member 105a removes the liquid component from the ink image on the transfer body. It is particularly preferable that the liquid absorbing member 105a is pressed against the transfer body 101 with a predetermined pressing force in this contacted state from the viewpoint of effectively functioning the liquid absorbing member 105a.

Explaining the removal of the liquid component from a different viewpoint, it can also be expressed as concentrating the ink constituting the image formed on the transfer body. Concentrating the ink means that the liquid component contained in the ink is reduced, so that the content ratio of the solid content such as the coloring material and the resin contained in the ink to the liquid component is increased.

Then, the ink image after the liquid removal from which the liquid component has been removed is in a state where the ink is concentrated as compared with the ink image before the liquid removal, and the recording medium is further conveyed by the transfer body 101 by the recording medium transfer device 107. It is moved to the transfer unit 111 that comes into contact with 108. While the ink image after removing the liquid is in contact with the recording medium 108, the pressing member 106 presses the transfer body 101, so that the ink image is transferred onto the recording medium 108. The post-transfer ink image transferred onto the recording medium 108 is an inverted image of the ink image before liquid removal and the ink image after liquid removal.

In the present embodiment, since the reaction liquid is applied onto the transfer body and then the ink is applied to form an image, the reaction liquid does not react with the ink in the non-image region where the image by the ink is not formed. Remaining. In this apparatus, the liquid absorbing member 105a is in contact with not only the image but also the unreacted reaction liquid, and the liquid component of the reaction liquid is also removed.

Therefore, in the above, it is expressed and explained that the liquid component is removed from the image, but it does not mean that the liquid component is removed only from the image, and at least the liquid component should be removed from the image on the transfer body. It is used in the sense that it should be good.

The liquid component is not particularly limited as long as it does not have a constant shape, has fluidity, and has a substantially constant volume.

For example, water, an organic solvent, etc. contained in an ink or a reaction liquid can be mentioned as liquid components.

Each configuration of the transfer type inkjet recording apparatus of this embodiment will be described below.

<Transcribing body>
The transfer body 101 has a surface layer including an image forming surface. As the surface layer member, various materials such as resin and ceramic can be appropriately used, but a material having a high compressive elastic modulus is preferable in terms of durability and the like. Specific examples thereof include an acrylic resin, an acrylic silicone resin, a fluorine-containing resin, and a condensate obtained by condensing a hydrolyzable organosilicon compound. In order to improve the wettability, transferability, etc. of the reaction solution, it may be used after being surface-treated. Examples of the surface treatment include frame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, active energy ray irradiation treatment, ozone treatment, surfactant treatment, silane coupling treatment and the like. A plurality of these may be combined. Further, any surface shape can be provided on the surface layer.

Further, the transfer material preferably has a compression layer having a function of absorbing pressure fluctuations. By providing the compression layer, the compression layer absorbs the deformation, disperses the fluctuation against local pressure fluctuations, and can maintain good transferability even during high-speed printing. Examples of the member of the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, silicone rubber and the like. At the time of molding the rubber material, it is preferable that a predetermined amount of a vulcanizing agent, a vulcanization accelerator or the like is blended, and further, a foaming agent, hollow fine particles or a filler such as salt is blended as necessary to make the rubber material porous. As a result, since the bubble portion is compressed with a volume change in response to various pressure fluctuations, deformation in directions other than the compression direction is small, and more stable transferability and durability can be obtained. As the porous rubber material, there are a continuous pore structure in which each pore is continuous with each other and an independent pore structure in which each pore is independent. In the present invention, any structure may be used, and these structures may be used in combination.

Further, the transfer material preferably has an elastic layer between the surface layer and the compression layer. As the member of the elastic layer, various materials such as resin and ceramic can be appropriately used. Various elastomer materials and rubber materials are preferably used in terms of processing characteristics and the like. Specifically, for example, the common weight of fluorosilicone rubber, phenylsilicone rubber, fluororubber, chloroprene rubber, urethane rubber, nitrile rubber, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, and ethylene / propylene / butadiene. Combined, nitrile butadiene rubber and the like can be mentioned. In particular, silicone rubber, fluorosilicone rubber, and phenylsilicone rubber are preferable in terms of dimensional stability and durability because they have a small compression set. In addition, the change in elastic modulus with temperature is small, which is preferable in terms of transferability.

Various adhesives or double-sided tape may be used between the layers (surface layer, elastic layer, compression layer) constituting the transfer body to fix and hold them. Further, a reinforcing layer having a high compressive elastic modulus may be provided in order to suppress lateral elongation when mounted on the device and to maintain elasticity. Further, the woven fabric may be used as a reinforcing layer. The transfer body can be produced by arbitrarily combining each layer made of the above-mentioned material.

The size of the transfer body can be freely selected according to the target print image size. The shape of the transfer body is not particularly limited, and specific examples thereof include a sheet shape, a roller shape, a belt shape, and an endless web shape.

<Support member>
The transfer body 101 is supported on the support member 102. As a method of supporting the transfer body, various adhesives or double-sided tape may be used. Alternatively, by attaching an installation member made of metal, ceramic, resin, or the like to the transfer body, the transfer body may be supported on the support member 102 by using the installation member.

The support member 102 is required to have a certain level of structural strength from the viewpoint of transport accuracy and durability. As the material of the support member, metal, ceramic, resin or the like is preferably used. Above all, in addition to rigidity and dimensional accuracy that can withstand the pressure during transfer, aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, in order to reduce inertia during operation and improve control responsiveness, Polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, and alumina ceramics are preferably used. It is also preferable to use these in combination.

<Reaction solution applying device>
The inkjet recording device of the present embodiment includes a reaction solution applying device 103 that applies the reaction solution to the transfer body 101. When the reaction liquid comes into contact with the ink, the fluidity of the ink and / or a part of the ink composition on the ejected medium can be reduced, and bleeding and beading during image formation by the ink can be suppressed. it can. Specifically, the reactant contained in the reaction solution (also referred to as an ink thickening component) chemically reacts when it comes into contact with a coloring material, a resin, or the like that is a part of the composition constituting the ink. Or physically adsorb. This causes an increase in the viscosity of the entire ink and a local increase in viscosity due to agglutination of some of the components constituting the ink such as a coloring material, resulting in a partial fluidity of the ink and / or the ink composition. Can be reduced. The reaction solution application device 103 of FIG. 3 has a reaction solution accommodating portion 103a for accommodating the reaction solution and reaction solution application members 103b and 103c for applying the reaction solution in the reaction solution accommodating unit 103a onto the transfer body 101. The case of a roller is shown. The amount of the reaction solution to be applied is preferably ^{0.5 g / m 2} or more and 5 g / m ^{2 or less.}

The reaction solution applying device may be any device capable of applying the reaction solution onto the discharge medium, and various conventionally known devices can be appropriately used. Specific examples thereof include a gravure offset roller, an inkjet head, a die coating device (die coater), and a blade coating device (blade coater). The reaction liquid may be applied by the reaction liquid application device before the ink is applied or after the ink is applied, as long as it can be mixed (reacted) with the ink on the ejected medium. Preferably, the reaction solution is applied before applying the ink. By applying the reaction liquid before applying the ink, bleeding in which the adjacently applied inks are mixed with each other during image recording by the inkjet method, and bee in which the ink landed first is attracted to the ink landed later. It is also possible to suppress the ding.

<Reaction solution>
Hereinafter, each component constituting the reaction solution applied to the present embodiment will be described in detail.

(Reactant)
The reaction solution agglomerates components having anionic groups (resins, self-dispersing pigments, etc.) in the ink when it comes into contact with the ink, and contains a reactant. Examples of the reactant include a cationic component such as a polyvalent metal ion and a cationic resin, and an organic acid.

Examples of the polyvalent metal ion include divalent metal ions ^{such as Ca 2+} , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ^{2+ , Fe 3+} , Cr ³⁺ , Y ³⁺ and Al ^3+. The trivalent metal ion of is mentioned. In order to contain the polyvalent metal ion in the reaction solution, a polyvalent metal salt (which may be a hydrate) formed by bonding the polyvalent metal ion and the anion can be used. Examples of anions include Cl ⁻ , Br ⁻ , I ⁻ , ClO ⁻ , ClO ₂ ⁻ , ClO ₃ ⁻ , ClO ₄ ⁻ , NO ₂ ⁻ , NO ₃ ⁻ , SO ₄ ^2- , CO ₃ ^2- , and HCO ₃ Inorganic anions such as ⁻ , PO ₄ ^3- , HPO ₄ ^2- , and H ₂ PO ₄ ^{− ; HCOO −} , (COO ⁻ ) ₂ , COOH (COO ⁻ ), CH ₃ COO ⁻ , C ₂ H ₄ (COO ⁻⁾ ) ₂ , C ₆ H ₅ COO ⁻ , C ₆ H ₄ (COO ⁻ ) ₂ and CH ₃ SO ₃ ⁻ and other organic anions can be mentioned. When polyvalent metal ions are used as the reactant, the content (mass%) in terms of polyvalent metal salt in the reaction solution is 1.00% by mass or more and 20.00% by mass or less based on the total mass of the reaction solution. It is preferable to have.

The reaction solution containing an organic acid has a buffering ability in an acidic region (pH less than 7.0, preferably pH 2.0 to 5.0), so that the anionic group of the component present in the ink is made into an acid type. It agglomerates. Examples of organic acids include formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrolcarboxylic acid, furancarboxylic acid, picolinic acid, nicotinic acid, thiophenecarboxylic acid, levulinic acid, coumarin acid and the like. Monocarboxylic acids and salts thereof; dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, tartaric acid, and the like. Examples thereof include salts and hydrogen salts; tricarboxylic acids such as citric acid and trimellitic acid and salts thereof and hydrogen salts; tetracarboxylic acids such as pyromellitic acid and salts and hydrogen salts thereof. The content (mass%) of the organic acid in the reaction solution is preferably 1.00% by mass or more and 50.00% by mass or less.

Examples of the cationic resin include a resin having a structure of a primary amine and a resin having a structure of a quaternary ammonium salt. Specific examples thereof include resins having structures such as vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, and guanidine. In order to increase the solubility in the reaction solution, the cationic resin and the acidic compound can be used in combination, or the cationic resin can be quaternized. When a cationic resin is used as the reactant, the content (mass%) of the cationic resin in the reaction solution is 1.00% by mass or more and 10.00% by mass or less based on the total mass of the reaction solution. preferable.

(Ingredients other than reactants)
As the component other than the reactant, the same components as those mentioned above as those that can be used for ink, such as an aqueous medium and other additives, can be used.

<Ink application device>
The inkjet recording device of this embodiment has an ink applying device 104 that applies ink to the transfer body 101. The reaction liquid and the ink are mixed on the transfer body, an ink image is formed by the reaction liquid and the ink, and a liquid component is further absorbed from the ink image by the liquid absorbing device 105.

In this embodiment, an inkjet head is used as an ink applying device for applying ink. The inkjet head includes, for example, a form in which a film is boiled in the ink by an electric-heat converter to form bubbles to eject the ink, a form in which the ink is ejected by an electric-mechanical converter, and an ink jet head using static electricity. Examples thereof include a discharge form. In this embodiment, a known inkjet head can be used. Among them, those using an electric-heat converter are preferably used from the viewpoint of high-speed and high-density printing. Drawing receives an image signal and applies the required amount of ink to each position.

In the present embodiment, the inkjet head is a full-line head extended in the Y direction, and nozzles are arranged in a range covering the width of the image recording area of the maximum usable recording medium. The inkjet head has an ink ejection surface having a nozzle opened on its lower surface (transfer body 1 side), and the ink ejection surface faces the surface of the transfer body 1 with a minute gap (about several millimeters). ..

The amount of ink applied can be expressed by the density value of image data, the thickness of ink, etc., but in this embodiment, the amount of ink applied (g / g /) is the average value obtained by multiplying the mass of each ink dot by the number of ink dots applied and dividing by the print area. It was set to m ² ). The maximum amount of ink applied in the image region is the amount of ink applied in an area of at least 5 mm ² or more in the area used as information of the ejected medium from the viewpoint of removing the liquid component in the ink. Shown.

The ink applying device 104 may have a plurality of inkjet heads in order to apply color inks of each color on the ejected medium. For example, when forming each color image using yellow ink, magenta ink, cyan ink, and black ink, the ink applying device has four inkjet heads for ejecting the above four types of ink onto the ejected medium. become. Then, these four types of inks are arranged so as to be arranged in the X direction.

Further, the ink applying device may include an inkjet head that does not contain a coloring material, or even if it contains a coloring material, the proportion thereof is very low, and a substantially transparent clear ink is ejected. Then, this clear ink can be used to form an ink image together with the reaction liquid and the color ink. For example, this clear ink can be used to improve the glossiness of an image. It is advisable to appropriately adjust the resin components to be blended so that the transferred image has a glossy appearance, and further control the ejection position of the clear ink. Since it is desirable that the clear ink is on the surface layer side of the color ink in the final recorded matter, in the transfer body type recording device, the clear ink is applied onto the transfer body 1 before the color ink. Therefore, the inkjet head for clear ink can be arranged on the upstream side of the inkjet head for color ink in the moving direction of the transfer body 1 facing the ink applying device 104.

In addition to the glossy image, it can be used to improve the transferability of the image from the transfer body 1 to the recording medium. For example, a clear ink can be used as a transferability improving liquid to be imparted onto the transfer body 1 by containing a larger amount of a component exhibiting adhesiveness than the color ink and applying this to the color ink. For example, in the moving direction of the transfer body 1 facing the ink applying device 104, the inkjet head for clear ink for improving transferability is arranged on the downstream side of the inkjet head for color ink. Then, after the color ink is applied to the transfer body 101, the clear ink is applied on the transfer body after the color ink is applied, so that the clear ink is present on the outermost surface of the ink image. In the transfer of the ink image to the recording medium by the transfer unit 111, the clear ink on the surface of the ink image adheres to the recording medium 108 with a certain degree of adhesive force, whereby the ink image after liquid removal moves to the recording medium 108. It will be easier to do.

<Ink>
Hereinafter, each component constituting the ink applied to the present embodiment will be described in detail.

(Color material)
As the coloring material, pigments and dyes can be used. The content of the coloring material in the ink is preferably 0.5% by mass or more and 15.0% by mass or less, and 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink. Is more preferable.

Specific examples of the pigment include inorganic pigments such as carbon black and titanium oxide; and organic pigments such as azo, phthalocyanine, quinacridone, isoindolenone, imidazolone, diketopyrrolopyrrole, and dioxazine.

As a pigment dispersion method, a resin-dispersed pigment using a resin as a dispersant, a self-dispersing pigment in which a hydrophilic group is bonded to the particle surface of the pigment, or the like can be used. Further, a resin-bonded pigment in which an organic group containing a resin is chemically bonded to the surface of the pigment particles, a microcapsule pigment in which the surface of the pigment particles is coated with a resin or the like can be used.

As the resin dispersant for dispersing the pigment in the aqueous medium, it is preferable to use a resin dispersant capable of dispersing the pigment in the aqueous medium by the action of an anionic group. As the resin dispersant, a resin as described later can be preferably used, and more preferably a water-soluble resin can be used. The pigment content (% by mass) is preferably 0.3 times or more and 10.0 times or less in terms of mass ratio to the content of the resin dispersant (pigment / resin dispersant).

As the self-dispersing pigment, an anionic group such as a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group is used, which is bonded to the particle surface of the pigment directly or via another atomic group (-R-). be able to. The anionic group may be of either an acid type or a salt type, and when it is a salt type, it may be in a state in which a part thereof is dissociated or a state in which the whole is dissociated. Examples of the cation that becomes a counter ion when the anionic group is a salt type include alkali metal cations; ammonium; organic ammonium; and the like. Specific examples of the other atomic group (-R-) include a linear or branched alkylene group having 1 to 12 carbon atoms; an arylene group such as a phenylene group or a naphthylene group; a carbonyl group; an imino group; an amide group. A sulfonyl group; an ester group; an ether group and the like can be mentioned. Moreover, you may make a group which combined these groups.

As the dye, it is preferable to use a dye having an anionic group. Specific examples of the dye include dyes such as azo, triphenylmethane, (aza) phthalocyanine, xanthene, and anthrapyridone.

(resin)
The ink can contain a resin. The content (mass%) of the resin in the ink is preferably 0.1% by mass or more and 20.0% by mass or less, and 0.5% by mass or more and 15.0% by mass or less, based on the total mass of the ink. Is more preferable.

The resin can be added to the ink for the reasons of (i) stabilizing the dispersed state of the pigment, that is, (ii) improving various characteristics of the recorded image as the above-mentioned resin dispersant and its auxiliary. it can. Examples of the form of the resin include block copolymers, random copolymers, graft copolymers, and combinations thereof. Further, the resin may be in a state of being dissolved as a water-soluble resin in an aqueous medium, or may be in a state of being dispersed as resin particles in the aqueous medium. The resin particles do not have to contain a coloring material.

In the present invention, the fact that the resin is water-soluble means that when the resin is neutralized with an acid value and an equivalent amount of alkali, particles whose particle size can be measured by a dynamic light scattering method are not formed. To do. Whether or not the resin is water-soluble can be determined according to the method shown below. First, a liquid (resin solid content: 10% by mass) containing a resin neutralized with an alkali (sodium hydroxide, potassium hydroxide, etc.) equivalent to an acid value is prepared. Next, the prepared liquid is diluted 10-fold (volume basis) with pure water to prepare a sample solution. Then, when the particle size of the resin in the sample solution is measured by the dynamic light scattering method, if the particles having the particle size are not measured, it can be determined that the resin is water-soluble. The measurement conditions at this time can be set, for example, SetZero: 30 seconds, the number of measurements: 3 times, and the measurement time: 180 seconds. As the particle size distribution measuring device, a particle size analyzer (for example, trade name “UPA-EX150”, manufactured by Nikkiso Co., Ltd.) by a dynamic light scattering method can be used. Of course, the particle size distribution measuring device and the measuring conditions to be used are not limited to the above.

The acid value of the resin is preferably 100 mgKOH / g or more and 250 mgKOH / g or less in the case of a water-soluble resin, and 5 mgKOH / g or more and 100 mgKOH / g or less in the case of resin particles. The weight average molecular weight of the resin is preferably 3,000 or more and 15,000 or less in the case of a water-soluble resin, and preferably 1,000 or more and 2,000,000 or less in the case of resin particles. The volume average particle diameter measured by the dynamic light scattering method of the resin particles (measurement conditions are the same as described above) is preferably 100 nm or more and 500 nm or less.

Examples of the resin include acrylic resins, urethane resins, and olefin resins. Of these, acrylic resins and urethane resins are preferable.

The acrylic resin preferably has a hydrophilic unit and a hydrophobic unit as constituent units. Of these, a resin having a hydrophilic unit derived from (meth) acrylic acid and a hydrophobic unit derived from at least one of a monomer having an aromatic ring and a (meth) acrylic acid ester-based monomer is preferable. In particular, a resin having a hydrophilic unit derived from (meth) acrylic acid and a hydrophobic unit derived from at least one monomer of styrene and α-methylstyrene is preferable. Since these resins are likely to interact with pigments, they can be suitably used as resin dispersants for dispersing pigments.

The hydrophilic unit is a unit having a hydrophilic group such as an anionic group. The hydrophilic unit can be formed, for example, by polymerizing a hydrophilic monomer having a hydrophilic group. Specific examples of the hydrophilic monomer having a hydrophilic group include an acidic monomer having a carboxylic acid group such as (meth) acrylic acid, itaconic acid, maleic acid, and fumaric acid, and anions such as anhydrides and salts of these acidic monomers. Examples include sex monomers. Examples of the cation constituting the salt of the acidic monomer include ions such as lithium, sodium, potassium, ammonium and organic ammonium. A hydrophobic unit is a unit that does not have a hydrophilic group such as an anionic group. The hydrophobic unit can be formed, for example, by polymerizing a hydrophobic monomer having no hydrophilic group such as an anionic group. Specific examples of the hydrophobic monomer include monomers having an aromatic ring such as styrene, α-methylstyrene, and benzyl (meth) acrylate; methyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylate 2. -Examples include (meth) acrylic acid ester-based monomers such as ethylhexyl.

The urethane-based resin can be obtained, for example, by reacting a polyisocyanate with a polyol. Further, the chain extender may be further reacted. Examples of the olefin resin include polyethylene and polypropylene.

(Aqueous medium)
The ink may contain water or an aqueous medium which is a mixed solvent of water and a water-soluble organic solvent. As the water, it is preferable to use deionized water or ion-exchanged water. The water content (mass%) in the water-based ink is preferably 50.0% by mass or more and 95.0% by mass or less based on the total mass of the ink. The content (mass%) of the water-soluble organic solvent in the water-based ink is preferably 3.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. As the water-soluble organic solvent, any solvent that can be used for ink jet ink such as alcohols, (poly) alkylene glycols, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds can be used.

(Other additives)
In addition to the above components, various inks such as defoamers, surfactants, pH adjusters, viscosity regulators, rust inhibitors, preservatives, fungicides, antioxidants, antioxidants, etc. Additives may be included.

<Liquid absorber>
In the present embodiment, the liquid absorbing device 105 has a liquid absorbing member 105a and a liquid absorbing pressing member 105b that presses the liquid absorbing member 105a against the ink image on the transfer body 101. The shapes of the liquid absorbing member 105a and the pressing member 105b are not particularly limited. For example, as shown in FIG. 3, the pressing member 105b has a cylindrical shape, the liquid absorbing member 105a has a belt shape, and the cylindrical pressing member 105b presses the belt-shaped liquid absorbing member 105a against the transfer body 101. It may be a configuration. Further, the pressing member 105b has a cylindrical shape, the liquid absorbing member 105a has a cylindrical shape formed on the peripheral surface of the cylindrical pressing member 105b, and the cylindrical pressing member 105b has a cylindrical liquid absorbing member 105a. May be pressed against the transfer body.

In the present embodiment, the liquid absorbing member 105a is preferably in the shape of a belt in consideration of the space in the inkjet recording apparatus and the like.

Further, the liquid absorbing device 105 having such a belt-shaped liquid absorbing member 105a may have a tensioning member for stretching the liquid absorbing member 105a. In FIG. 3, 105c is a tension roller as a tension member. In FIG. 3, the pressing member 105b is also a roller member that rotates in the same manner as the tension roller, but the present invention is not limited to this.

In the liquid absorbing device 105, the liquid absorbing member 105a having a porous body is pressed against the ink image by the pressing member 105b and brought into contact with the liquid absorbing member 105a, so that the liquid component contained in the ink image is absorbed by the liquid absorbing member 105a and the liquid component is absorbed. Reduce. As a method of reducing the liquid component in the ink image, in addition to this method of contacting the liquid absorbing member, various other conventionally used methods such as a method of heating, a method of blowing low humidity air, a method of reducing the pressure, etc. May be combined. Further, these methods may be applied to the ink image after removing the liquid in which the liquid component is reduced to further reduce the liquid component.

<Liquid absorption member>
In the present embodiment, at least a part of the liquid component is removed from the ink image before the liquid removal by contacting with a liquid absorbing member having a porous body to absorb the liquid component, and the content of the liquid component in the ink image is reduced. Let me. The contact surface of the liquid absorbing member with the ink image is set as the first surface, and the porous body is arranged on the first surface. The liquid absorbing member having such a porous body moves in conjunction with the movement of the ejected medium, and after contacting with the ink image, circulates to recontact with another ink image before liquid removal at a predetermined cycle. It is preferable that the ink has a shape capable of absorbing liquid. For example, a shape such as an endless belt shape or a drum shape can be mentioned.

(Porous medium)
The porous body in the present embodiment has a hydrophilic porous layer and a water-repellent porous layer on the hydrophilic porous layer. The surface (first surface) on the side where the water-repellent porous layer of the porous body exists is the surface that comes into contact with the ink image on the ejected medium.

The average pore diameter of the water-repellent porous layer is not less than or equal to the average pore diameter of the hydrophilic porous layer and less than or equal to the dot diameter of the agglomerates formed by one drop of ink droplets among the agglomerates. For example, there are no particular restrictions.

Specifically, the average pore diameter of the hydrophilic porous layer is preferably 0.1 μm or more and 5.0 μm or less from the viewpoint of absorption of liquid components. The average pore size of the water-repellent porous layer is preferably 0.1 μm or more and 10.0 μm or less from the viewpoint of absorption of liquid components. The average pore diameter of the hydrophilic porous layer and the average pore diameter of the water-repellent porous layer can both be measured by a mercury press-fitting method or the like.

The porosity of the hydrophilic porous layer is preferably 20% or more and 90% or less, preferably 40% or more and 80% or more, based on the total volume of the hydrophilic porous layer from the viewpoint of absorption of liquid components. More preferably, it is less than%. Further, the porosity of the hydrophobic porous body is preferably 20% or more and 90% or less, preferably 40%, based on the total volume of the water-repellent porous layer from the viewpoint of absorption of liquid components. More preferably, it is 80% or more and 80% or less. Both the porosity of the hydrophilic porous layer and the porosity of the water-repellent porous layer can be measured by a mercury intrusion method or the like.

The contact angle of water on the surface of the hydrophilic porous layer is less than 90 °. The contact angle of water on the surface of the water-repellent porous layer is 90 ° or more. The contact angle of these waters can be measured according to the technique described in "6. Static method" of JIS R3257. The materials constituting the hydrophilic and water-repellent porous layers are not particularly limited as long as they each exhibit the above-mentioned contact angle of water. Examples of the material constituting the hydrophilic porous layer include a single material such as cellulose and polyacrylamide, a composite material thereof, and a metal or ceramics such as alumina. From the viewpoint of durability, metals such as alumina and ceramics are preferable.

Examples of the material constituting the water-repellent porous layer include fluororesin and the like. Specific examples of the fluororesin include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), vinyl fluoride (PVF), perfluoroalkoxyfluororesin (PFA), and four. Examples thereof include ethylene fluoride / propylene hexafluoride copolymer (FEP), ethylene / ethylene tetrafluoride copolymer (ETFE), and ethylene / chlorotrifluoroethylene copolymer (ECTFE).

The thickness T of the water-repellent porous layer of the porous body in the formula (1) is not particularly limited as long as the relationship of the formula (1) is satisfied. From the viewpoint of the permeability of the water-repellent porous layer of the liquid component, the thickness T is preferably equal to or less than the average pore diameter of the water-repellent porous layer. Specifically, the thickness T is preferably 4.5 μm or less, and more preferably 0.001 μm or more and 4.5 μm or less. The thickness T of the water-repellent porous layer can be measured from a microscope image such as an SEM image of a cross section of the porous body. Further, the water-repellent porous layer does not necessarily cover the entire surface of the hydrophilic porous layer, but may cover at least a part of the surface of the hydrophilic porous layer.

Further, it is preferable that the pores of the water-repellent porous layer communicate with the pores of the hydrophilic porous layer. By satisfying the above formula (1) by communicating the pores with each other, the liquid component passes through the water-repellent porous body and easily comes into contact with the pores of the hydrophilic porous layer. As a result, the liquid component separated from the ink agglomerates by pressure slides in the pores of the water-repellent porous layer, and can be absorbed by the capillary force of the hydrophilic porous layer.

The surface roughness Ra of the first surface of the porous body, which is the surface in contact with the ink image, is preferably 0.2 μm or less from the viewpoint of suppressing adhesion of the coloring material. The surface roughness Ra is an arithmetic mean roughness and can be measured by a known method.

It is preferable that the porous body is in contact with the agglomerate while applying pressure. The pressure at this time is preferably 1 kgf / cm ² or more because the liquid component contained in the agglomerate can be solid-liquid separated and the liquid component can be efficiently absorbed. Further, the action time of this pressure is preferably 50 ms or less, and more preferably 10 to 20 ms in order to suppress the influence on the ink image as much as possible.

(Manufacturing method of porous body)
The method for forming a porous body by laminating a water-repellent porous layer and a hydrophilic porous layer is not particularly limited. They may simply be superposed or bonded to each other using methods such as adhesive laminating or thermal laminating. From the viewpoint of breathability, thermal lamination is preferable in this embodiment. For example, a part of the first layer or the second layer may be melted by heating and adhered and laminated. Further, a fusion material such as hot melt powder may be interposed between the first layer and the second layer and adhered and laminated to each other by heating. When laminating the third layer or more, they may be laminated at once or sequentially, and the stacking order is appropriately selected.

In the heating step, a laminating method in which the porous body is heated by sandwiching the porous body with heated rollers and pressurizing the porous body is preferable.

Further, the water-repellent porous layer may be formed by subjecting the surface of the hydrophilic porous layer to a water-repellent treatment. For example, the surface of the hydrophilic porous layer is thinned by so-called SAM (self-assembled monolayer) treatment or DLC (diamond-like carbon) treatment with a material containing low surface energy such as fluorine. It is preferable to form a water repellent layer.

Hereinafter, various conditions and configurations of the liquid absorbing device 105 will be described in detail.

(Pressurization condition)
If the pressure of the liquid absorbing member at the time of contact with the ink image on the transfer body is 2.9 N / cm ² (0.3 kgf / cm ² ) or more, the liquid component in the ink image is solidified in a shorter time. It is preferable because the liquid can be separated and the liquid component can be removed from the ink image. The pressure of the liquid absorbing member in the present specification indicates the nip pressure between the discharged medium and the liquid absorbing member, and is a surface pressure distribution measuring instrument (“I-SCAN”, manufactured by Nitta Co., Ltd.). The surface pressure was measured using the above, and the weight in the pressurized region was divided by the area to calculate the value.

(Time of action)
The action time for bringing the liquid absorbing member 105a into contact with the ink image is preferably 50 ms or less in order to further suppress the coloring material in the ink image from adhering to the liquid absorbing member. The action time in the present specification is calculated by dividing the pressure sensing width in the moving direction of the discharged medium in the above-mentioned surface pressure measurement by the moving speed of the discharged medium. Hereinafter, this action time will be referred to as a liquid absorption nip time.

In this way, the liquid component is absorbed on the transfer body 101, and an ink image in which the liquid component is reduced is formed. The ink image after removing the liquid is then transferred onto the recording medium 108 by the transfer unit 111. The apparatus configuration and conditions at the time of transfer will be described.

<Pressing member for transfer>
In the present embodiment, the ink image after removing the liquid on the transfer body 101 is transferred onto the recording medium 108 conveyed by the recording medium conveying means 107 by contacting the ink image on the transfer body 101 with the recording medium 108 by the transfer pressing member 106. By removing the liquid component contained in the ink image on the transfer body 101 and then transferring the liquid component to the recording medium 108, it is possible to obtain a recorded image in which curling, cockling, and the like are suppressed.

The pressing member 106 is required to have a certain level of structural strength from the viewpoint of transport accuracy and durability of the recording medium 108. As the material of the pressing member 106, metal, ceramic, resin or the like is preferably used. Above all, in addition to rigidity and dimensional accuracy that can withstand the pressure during transfer, aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, in order to reduce inertia during operation and improve control responsiveness, Polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, and alumina ceramics are preferably used. Moreover, you may use these in combination.

There is no particular limitation on the pressing time for the pressing member 106 to press the transfer body in order to transfer the ink image after removing the liquid on the transfer body 101 to the recording medium 108. The pressing time is preferably 5 ms or more and 100 ms or less so that the transfer is performed well and the durability of the transferred product is not impaired. The pressing time in the present embodiment indicates the time during which the recording medium 108 and the transfer body 101 are in contact with each other, and a surface pressure distribution measuring device (“I-SCAN”, manufactured by Nitta Co., Ltd.) is used. The surface pressure was measured, and the length of the pressurized region in the transport direction was divided by the transport speed to calculate the value.

Further, there is no particular limitation on the pressure at which the pressing member 106 presses the transfer body 101 in order to transfer the ink image after removing the liquid on the transfer body 101 to the recording medium 108. ^{The pressure is 9.8 N / cm 2} (1 kg / cm ² ) or more and 294.2 N / cm ² (30 kg / cm ² ) so that the transfer is performed well and the durability of the transfer material is not impaired. The following is preferable. The pressure in the present embodiment indicates the nip pressure between the recording medium 108 and the transfer body 101, the surface pressure is measured using a surface pressure distribution measuring device, and the load in the pressure region is divided by the area. The value is calculated.

The temperature when the pressing member 106 is pressing the transfer body 101 in order to transfer the ink image after removing the liquid on the transfer body 101 to the recording medium 108 is also not particularly limited, but the resin component contained in the ink is not particularly limited. It is preferably at least the glass transition point or at least the softening point. Further, for heating, it is preferable to include a heating means for heating the second image on the transfer body 101, the transfer body 101, and the recording medium 108.

The shape of the transfer means 106 is not particularly limited, and examples thereof include a roller shape.

<Recording medium and recording medium transfer device>
In the present embodiment, the recording medium 108 is not particularly limited, and any known recording medium can be used. Examples of the recording medium include long ones wound in a roll shape and single-striped ones cut to a predetermined size. Examples of the material include paper, plastic film, wooden board, corrugated cardboard, metal film and the like.

Further, in FIG. 3, the recording medium transporting device 107 for transporting the recording medium 108 is composed of the recording medium feeding roller 107a and the recording medium winding roller 107b, but it is sufficient if the recording medium can be conveyed, and this configuration is particularly important. It is not limited to.

<Control system>
The transfer type inkjet recording device in the present embodiment has a control system that controls each device. FIG. 5 is a block diagram showing a control system of the entire device in the transfer type inkjet recording device shown in FIG.

In FIG. 5, 301 is a recording data generation unit such as an external print server, 302 is an operation control unit such as an operation panel, 303 is a printer control unit for executing a recording process, and 304 is a recording medium for transporting a recording medium. The transfer control unit, 305, is an inkjet device for printing.

FIG. 6 is a block diagram of a printer control unit in the transfer type inkjet recording apparatus of FIG.

401 is a CPU that controls the entire printer, 402 is a ROM for storing the control program of the CPU 401, and 403 is a RAM for executing the program. Reference numeral 404 is an integrated circuit (Application Specific Integrated Circuit: ASIC) for a specific application, which incorporates a network controller, a serial IF controller, a head data generation controller, a motor controller, and the like. Reference numeral 405 is a liquid absorbing member transport control unit for driving the liquid absorbing member transport motor 406, which is command controlled from the ASIC 404 via the serial IF. Reference numeral 407 is a transfer body drive control unit for driving the transfer body drive motor 408, which is also command-controlled from the ASIC 404 via the serial IF. Reference numeral 409 is a head control unit, which generates final ejection data of the inkjet device 305, generates a driving voltage, and the like.

(Direct drawing type inkjet recording device)
Another embodiment of the present embodiment is a direct drawing type inkjet recording apparatus. In the direct drawing type inkjet recording apparatus, the ejection medium is a recording medium on which an image should be formed.

FIG. 4 is a schematic view showing an example of a schematic configuration of the direct drawing type inkjet recording apparatus 200 according to the present embodiment. Compared with the transfer type inkjet recording device, the direct drawing type inkjet recording device does not have the transfer body 101, the support member 102, and the transfer body cleaning member 109, and transfers the image except that the image is formed on the recording medium 208. It has the same means as the type inkjet recording device.

Therefore, the ink image is formed by the reaction liquid applying device 203 that applies the reaction liquid to the recording medium 208, the ink applying device 204 that applies ink to the recording medium 208, and the liquid absorbing member 205a that comes into contact with the ink image on the recording medium 208. The liquid absorbing device 205 for absorbing the liquid component contained in the above has the same configuration as the transfer type inkjet recording device, and the description thereof will be omitted.

In the direct drawing type inkjet recording apparatus of the present embodiment, the liquid absorbing device 205 has a liquid absorbing member 205a and a pressing member 205b for liquid absorption that presses the liquid absorbing member 205a against the ink image on the recording medium 208. .. The shapes of the liquid absorbing member 205a and the pressing member 205b are not particularly limited, and those having the same shape as the liquid absorbing member and the pressing member that can be used in the transfer type inkjet recording device can be used. Further, the liquid absorbing device 205 may have a tensioning member for tensioning the liquid absorbing member. In FIG. 4, 205c, 205d, 205e, 205f, 205g are tension rollers as tension members. The number of tension rollers is not limited to the five in FIG. 4, and the required number may be arranged according to the device design. Further, the ink applying unit that applies ink to the recording medium 208 by the ink applying device 204 and the liquid component removing unit that contacts the liquid absorbing member 205a with the ink image on the recording medium to remove the liquid component are provided with a recording medium. A recording medium support member (not shown) may be provided to support the ink from below.

<Recording medium transfer device>
In the direct drawing type inkjet recording apparatus of the present embodiment, the recording medium conveying device 207 is not particularly limited, and the conveying means in the known direct drawing type inkjet recording apparatus can be used. As an example, as shown in FIG. 4, a recording medium conveying device having a recording medium feeding roller 207a, a recording medium winding roller 207b, and a recording medium conveying roller 207c, 207d, 207e, 207f can be mentioned.

<Control system>
The direct drawing type inkjet recording device in the present embodiment has a control system for controlling each device. The block diagram showing the control system of the entire device in the direct drawing type inkjet recording device shown in FIG. 4 is as shown in FIG. 5, similar to the transfer type inkjet recording device shown in FIG.

FIG. 7 is a block diagram of a printer control unit in the direct drawing type inkjet recording apparatus of FIG. It is the same as the block diagram of the printer control unit in the transfer type inkjet recording apparatus shown in FIG. 6 except that the transfer body drive control unit 407 and the transfer body drive motor 408 are not provided.

That is, 501 is a CPU that controls the entire printer, 502 is a ROM for storing the control program of the CPU, and 503 is a RAM for executing the program. Reference numeral 504 is an ASIC having a built-in network controller, serial IF controller, head data generation controller, motor controller, and the like. Reference numeral 505 is a liquid absorbing member transport control unit for driving the liquid absorbing member transport motor 506, which is command controlled from the ASIC 504 via the serial IF. Reference numeral 509th is a head control unit, which generates final ejection data of the inkjet device 305, generates a drive voltage, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the description of the following examples, the term "part" is based on mass unless otherwise specified.

(Example 1)
<Preparation of resin particles>
18.0 parts of butyl methacrylate, polymerization initiator (2,2'-azobis (2-methylbutyronitrile)) 2.0 in a four-necked flask equipped with a stirrer, a reflux cooling device, and a nitrogen gas introduction tube. A portion and 2.0 parts of n-hexadecane were added, nitrogen gas was introduced into the reaction system, and the mixture was stirred for 0.5 hours. 78.0 parts of a 6.0% aqueous solution of an emulsifier (NIKKOL BC15, manufactured by Nikko Chemicals Co., Ltd.) was added dropwise to this flask, and the mixture was stirred for 0.5 hours. The mixture was then emulsified by irradiating the mixture with ultrasonic waves for 3 hours with an ultrasonic irradiator. Then, the polymerization reaction was carried out at 80 ° C. for 4 hours in a nitrogen atmosphere. After cooling the reaction system to 25 ° C., the components are filtered and an appropriate amount of pure water is added to prepare an aqueous dispersion of resin particles 1 having a resin particle 1 (solid content) content of 20.0%. did.

Further, an aqueous dispersion of the resin particles 2 having a resin particle 2 (solid content) content of 20.0% was prepared by the same procedure as the preparation of the resin particles 1 except that butyl methacrylate was changed to ethyl methacrylate. did.

<Preparation of aqueous resin solution>
A styrene-ethyl acrylate-acrylic acid copolymer (resin 1) having an acid value of 150 mgKOH / g and a weight average molecular weight of 8,000 was prepared. 20.0 parts of resin 1 is neutralized with potassium hydroxide having an acid value equal to that of the resin 1, an appropriate amount of pure water is added, and an aqueous solution of resin 1 having a resin (solid content) content of 20.0%. Was prepared.

Further, the resin 1 was changed to a styrene-butyl acrylate-acrylic acid copolymer (resin 2) having an acid value of 132 mgKOH / g, a weight average molecular weight of 7,700, and a glass transition temperature of 78 ° C. Except for this, an aqueous solution of resin 2 having a resin (solid content) content of 20.0% was prepared in the same procedure as the preparation of the aqueous solution of resin 1.

<Preparation of reaction solution>
Each of the following components was mixed and sufficiently stirred, and then pressure filtration was performed with a cellulose acetate filter (manufactured by Advantech) having a pore size of 3.0 μm to prepare a reaction solution.
・ Levulinic acid: 40.0 parts ・ Glycerin: 5.0 parts ・ Megafuck F444: 1.0 parts (surfactant, manufactured by DIC)
・ Ion-exchanged water: 54.0 parts <Ink preparation>
(Preparation of pigment dispersion)
10.0 parts of pigment (carbon black), 15.0 parts of an aqueous solution of resin 1, and 75.0 parts of pure water were mixed. This mixture and 200 parts of 0.3 mm diameter zirconia beads were placed in a batch type vertical sand mill (manufactured by Imex) and dispersed for 5 hours while cooling with water. Then, it is centrifuged to remove coarse particles, and pressure-filtered with a cellulose acetate filter (manufactured by Advantech) having a pore size of 3.0 μm to obtain a pigment content of 10.0% and a resin dispersant (resin 1). A pigment dispersion K having a content of 3.0% was prepared.

(Ink preparation)
Each component shown in Table 1 below was mixed, and after sufficient stirring, pressure filtration was performed with a cellulose acetate filter (manufactured by Advantech) having a pore size of 3.0 μm to prepare a black ink. Acetylenol E100 is a surfactant manufactured by Kawaken Fine Chemicals.

<Preparation of porous body>
As the porous body, a roller-shaped hydrophilic alumina porous layer (average pore diameter of 0.5 μm) was water-repellent by depositing fluorinated diamond-like carbon on the surface. This water-repellent treated portion constitutes a water-repellent porous layer. Since the average pore diameter of the water-repellent porous layer was treated on the surface of the porous body, it was 0.5 μm, which was the same as that of the hydrophilic porous layer. The porosity of the hydrophilic and water-repellent porous layers was 40%. The thickness of the water-repellent porous layer was 4.5 μm. The contact angle of water on the surface of the water-repellent porous layer was 90 ° or more. The surface roughness Ra of the first surface of the porous body, which is the surface in contact with the ink image, was set to 0.2 μm.

<Inkjet recording device and image formation>
In the transfer type inkjet recording device shown in FIG. 3, an image was formed by changing the liquid absorbing device 105 to the above-mentioned liquid absorbing member having a roller-shaped porous body as the inkjet recording device. Table 2 shows the average pore diameter, porosity A, thickness T, water contact angle, and surface roughness of the water-repellent porous layer of the porous body used.

As the transcript 101, the one having the following constitution was used.

A sheet obtained by coating a PET sheet having a thickness of 0.5 mm with silicone rubber (KE12 manufactured by Shin-Etsu Chemical Co., Ltd.) to a thickness of 0.3 mm was used as the elastic layer of the transfer body. Further, glycidoxypropyltriethoxysilane and methyltriethoxysilane were mixed at a molar ratio of 1: 1 to prepare a mixture of a condensate obtained by heating and refluxing and a photocationic polymerization initiator (SP150 manufactured by ADEKA). Atmospheric pressure plasma treatment was performed so that the contact angle of water on the surface of the elastic layer was 10 degrees or less, and the mixture was applied onto the elastic layer. The mixture applied on the elastic layer is subjected to UV irradiation (high pressure mercury lamp, integrated exposure amount of 5000 mJ / cm ² ), and further heat (150 ° C., 2 hours) is applied to cure the mixture, and the elastic layer is formed. A transfer body 101 having a surface layer having a thickness of 0.5 μm formed therein was prepared.

In this configuration, although not shown for the sake of brevity, a double-sided tape was used to hold the transfer body 101 between the transfer body 101 and the support member 102.

Further, in this configuration, the temperature of the surface of the transfer body 101 is adjusted to 60 ° C. by a heating means (not shown).

The amount of the reaction solution applied by the reaction solution application device 103 was 0.5 g / m ² .

The ink application device 104 used an inkjet recording head of a type that uses an electric-heat conversion element to eject ink in an on-demand manner. The amount of the ink applied in the image formation was 20 g / m ² .

The recording medium 108 is conveyed by the recording medium feeding roller 107a and the recording medium winding roller 107b. In this example, the transport speed was 0.1 m / s, and Aurora coated paper (manufactured by Nippon Paper Industries, Ltd., basis weight 104 g / m ² ) was used as the recording medium 108.

<Ink droplet ejection amount and agglomerate thickness>
The amount of ink droplets ejected from the inkjet recording head was 3 pl ink droplets. The thickness D and the dot diameter of the formed agglomerates were measured. Further, the liquid ratio P of the agglomerates was calculated from the liquid components of the ink and the reaction liquid.

<Conditions for contact of the porous body of the liquid absorbing member with agglomerates>
Table 2 shows the contact conditions (pressure, action time) of the porous body of the liquid absorbing member with the agglomerates.

<Fixing>
Then, the final printed matter was obtained by thermocompression bonding to the ejected medium using a fixing roller.

(Example 2)
As the porous body, a roller-shaped hydrophilic alumina porous layer (average pore diameter of 0.2 μm) was water-repellent by depositing fluorinated diamond-like carbon on the surface. A printed matter was obtained in the same manner as in Example 1 except that the contact conditions of the water-repellent porous layer, the agglomerates, and the porous body were adjusted as shown in Table 2.

(Example 3)
As the porous body, a roller-shaped hydrophilic alumina porous layer (average pore diameter of 0.5 μm) was water-repellent by depositing fluorinated diamond-like carbon on the surface. A printed matter was obtained in the same manner as in Example 1 except that the physical characteristics of the water-repellent porous layer, the physical characteristics of the agglomerates, and the contact conditions of the porous body were adjusted as shown in Table 2.

(Example 4)
As the porous body, a roller-shaped hydrophilic alumina porous layer (average pore diameter of 1.0 μm) was water-repellent by depositing fluorinated diamond-like carbon on the surface. Further, the thickness of the agglomerates and the dot diameter were adjusted by setting the ejection amount of the ink droplets to 15 pl. A printed matter was obtained in the same manner as in Example 1 except that the physical characteristics of the water-repellent porous layer, the physical characteristics of the agglomerates, and the contact conditions of the porous body were adjusted as shown in Table 2.

(Example 5)
As the porous body, a roller-shaped hydrophilic alumina porous layer (average pore diameter of 0.2 μm) was water-repellent by depositing fluorinated diamond-like carbon on the surface. A printed matter was obtained in the same manner as in Example 1 except that the physical characteristics of the water-repellent porous layer, the physical characteristics of the agglomerates, and the contact conditions of the porous body were adjusted as shown in Table 2.

(Comparative Example 1)
As a porous body, the surface of a roller-shaped hydrophilic alumina porous layer (average pore diameter 0.2 μm) is hydrophilized with a thickness of 20.0 μm (average pore diameter 0.5 μm). Was used. The porosity of this hydrophilic PTFE porous layer was 40%. Further, the contact angle of water on the surface of the hydrophilic PTFE porous layer was less than 90 °. The surface roughness Ra of the first surface of the porous body, which is the surface in contact with the ink image, was set to 0.2 μm. Further, the ejection amount of the ink droplet was set to 15 pl, and the thickness of the aggregate and the dot diameter were adjusted. A printed matter was obtained in the same manner as in Example 1 except that the physical characteristics of the water-repellent porous layer, the physical characteristics of the agglomerates, and the contact conditions of the porous body were adjusted as shown in Table 2. In Table 2, the physical properties are described in the column of the water-repellent porous layer, which is the physical properties of the hydrophilic PTFE porous layer.

(Comparative Example 2)
As the porous body, a roller-shaped hydrophilic alumina porous layer (average pore diameter of 500 μm) was water-repellent by depositing fluorinated diamond-like carbon on the surface. A printed matter was obtained in the same manner as in Example 1 except that the physical characteristics of the water-repellent porous layer, the physical characteristics of the agglomerates, and the contact conditions of the porous body were adjusted as shown in Table 2.

(Comparative Example 3)
As the porous body, a roller-shaped hydrophilic alumina porous layer (average pore diameter of 1.0 μm) was water-repellent by depositing fluorinated diamond-like carbon on the surface.

A printed matter was obtained in the same manner as in Example 1 except that the physical characteristics of the water-repellent porous layer, the physical characteristics of the agglomerates, and the contact conditions of the porous body were adjusted as shown in Table 2.

[Evaluation]
The curl / cockling, color transfer property, and image flow of the printed matter obtained by using the above-mentioned porous materials were evaluated as follows. The evaluation results are shown in Table 3. In the present invention, the evaluation criteria A to B of each of the following evaluation items are set to preferable levels, and C is set to an unacceptable level.

(Evaluation of curls and cock rings)
A solid image was separately printed on the recording medium to prepare a printed matter. The obtained printed matter was evaluated using the following evaluation criteria. A solid image is an image in which one drop of ink is added to one pixel of 1200 dpi.

The evaluation criteria for curls and cock rings are as follows. The deformation rate is the ratio of the change in the length of the surface of the recording medium due to the expansion of the recording medium after the ink is applied to the recording medium before the ink is applied, and is a so-called cockling index.
A: The average floating of the four corners of the printed matter was less than 2 mm, and the cock ring was not visible (deformation rate within 50 ppm).
B: The average floating of the four corners of the printed matter was less than 5 mm, and the cock ring was visible but acceptable (deformation rate within 100 ppm).
C: The average floating of the four corners of the printed matter was 5 mm or more, or cockling was observed (deformation rate of 100 ppm or more).

(Evaluation of color material adhesion)
After forming the printed matter, the adhesion state of the coloring material on the surface of the porous body was observed, and the adhesion rate of the coloring material was calculated. For this evaluation, the following printed matter was produced. First, 20 dots were printed on the transfer body. Let this number of dots be A. Then, the number of dots B remaining on the transfer body after the ink image is transferred to the recording medium is counted, a calculation is performed based on the following formula (2), and the obtained value is defined as the color material adhesion rate. did.

Color material adhesion rate (%) = 100-((AB) / A) x 100 formula (2)
The evaluation criteria for color material adhesion are as follows. In Table 2, when the liquid component is difficult to penetrate and the image is distorted, it is described as "-".
A: Color material adhesion rate ≤ 10%
C: Color material adhesion rate> 10%
(Evaluation of image flow)
The amount of movement of the coloring material at the edge of the image after the liquid is removed under the conditions of the above-mentioned Examples and Comparative Examples is shown, and the smaller the amount of movement, the higher the image quality and the more preferable. The evaluation criteria are as follows.
A: No image flow occurred even after repeated use.
B: There was a slight image flow, but it was a level that was not noticeable.
C: Image flow has occurred.

Further, instead of the transfer type inkjet recording apparatus, the same experiment was conducted using the direct drawing type inkjet recording apparatus shown in FIG. 4 in which the reaction solution was directly applied to the recording medium and the ink was applied. In the image evaluation in the direct drawing type inkjet recording apparatus shown in FIG. 4, Gloria Pure White paper basis weight 210 g / m ² (manufactured by Gojo Paper Manufacturing Co., Ltd.) was used as the recording medium.

The reaction liquid composition, the reaction liquid applying means 203, the ink composition, the ink applying means 204, the transport speed of the recording medium, and the liquid removing means 205 other than the recording medium have the same conditions as those of the transfer type inkjet recording apparatus used in Example 1. It has become.

As a result, it was confirmed that good results were obtained as in the case of the transfer type inkjet recording apparatus evaluated in the above example.

100 Transfer type inkjet recording device 101 Transfer member 105 Liquid absorption device 105a Liquid absorption member 105b Pressing member 108 Recording medium 200 Direct drawing type inkjet recording device 205 Liquid absorption device 205a Liquid absorption member 205b Pressing member 208 Recording medium

Claims (12)

A step of applying an ink containing a coloring material and a reaction liquid that agglomerates the coloring material to a medium to be ejected to form an ink image having a liquid component and agglomerates containing the coloring material.
A step of bringing the first surface of the porous body of the liquid absorbing member into contact with the ink image on the ejected medium to remove at least a part of the liquid component from the ink image.
It is an inkjet recording method having
The porous body has a hydrophilic porous layer and a water-repellent porous layer on the hydrophilic porous layer.
The first surface is the surface on the side where the water-repellent porous layer is present.
The average pore diameter of the water-repellent porous layer is equal to or greater than the average pore diameter of the hydrophilic porous layer and equal to or less than the dot diameter of the agglomerates formed by one drop of ink droplets of the agglomerates. And
The thickness of the water-repellent porous layer is T (μm), the porosity of the water-repellent porous layer is A (%), and the thickness of the agglomerates formed by the single drop of ink is D (μm). When the ratio of the liquid component of the agglomerate formed by the one drop of ink is P (%), the T, the A, the D, and the P satisfy the relationship of the following formula (1). Ink recording method.
T <D × P / A formula (1) The inkjet recording method according to claim 1, wherein D is 4.5 μm or less. The inkjet recording method according to claim 1 or 2, wherein T is equal to or smaller than the average pore diameter of the water-repellent porous layer. The inkjet recording method according to any one of claims 1 to 3, wherein the surface roughness Ra of the first surface is 0.2 μm or less. The inkjet recording method according to any one of claims 1 to 4, wherein the porous body is in contact with the agglomerate while applying pressure. Any of claims 1 to 5, wherein the ejected medium is a transfer body that temporarily holds the ink image, and has a step of transferring the ink image from which the liquid component has been removed from the transfer body to a recording medium. The inkjet recording method according to claim 1. Discharge medium and
A reaction liquid applying device that applies a reaction liquid that agglutinates the coloring material contained in the ink onto the ejection medium, and
An ink application device having an inkjet head that ejects ink containing a coloring material onto the ejected medium, and an ink applying device.
A liquid having a porous body that comes into contact with the reaction liquid and an ink image having an agglomerate containing a liquid component and a coloring material formed by the ink and absorbs at least a part of the liquid component from the ink image. Absorbent member and
Inkjet recording device with
The porous body has a hydrophilic porous layer and a water-repellent porous layer on the hydrophilic porous layer.
The liquid absorbing member is arranged so that the first surface of the porous body in contact with the ink image is the surface on the side where the water-repellent porous layer exists.
The average pore diameter of the water-repellent porous body is equal to or larger than the average pore diameter of the hydrophilic porous layer and equal to or smaller than the dot diameter of the aggregate formed by one drop of ink droplets among the aggregates. And
The thickness of the water-repellent porous layer is T (μm), the porosity of the water-repellent porous layer is A (%), and the thickness of the agglomerates formed by the single drop of ink is D (μm). When the ratio of the liquid component of the agglomerate formed by the one drop of ink is P (%), the T, the A, the D, and the P satisfy the relationship of the following formula (1). Ink recording device.
T <D × P / A formula (1) The inkjet recording apparatus according to claim 7, wherein D is 4.5 μm or less. The inkjet recording apparatus according to claim 7 or 8, wherein T is equal to or smaller than the average pore diameter of the water-repellent porous layer. The inkjet recording apparatus according to any one of claims 7 to 9, wherein the surface roughness Ra of the first surface is 0.2 μm or less. The inkjet recording apparatus according to any one of claims 7 to 10, further comprising a pressing member for absorbing a liquid that brings the porous body into contact with the agglomerate while applying pressure. 7. A claim 7 in which the ejected medium is a transfer body that temporarily holds the ink image, and has a transfer pressing member that transfers the ink image from which the liquid component has been removed from the transfer body to a recording medium. The inkjet recording apparatus according to any one of items 11 to 11.

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