JP2023019460A - Inkjet recording device - Google Patents

Abstract

To solve such the problem that contact pressure varies in a liquid absorption part because of permanent set of a transfer body due to thermal expansion or long-term use.SOLUTION: An inkjet recording device includes pressing means for pressing a liquid absorption member, which is provided with an elastic function, thereby preferably removing liquid even when the thickness of a transfer body varies.SELECTED DRAWING: Figure 9

Description

The present invention relates to an inkjet recording apparatus.

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 and cockling may occur due to excessive absorption of liquid components in the ink by the recording medium.

Therefore, in order to quickly remove the liquid component in the ink, there is a method of drying the recording medium, an image is formed on the transfer body, and then the liquid component contained in the image on the transfer body is dried by heat energy or the like. , a method of transferring an image to a recording medium such as paper.

Furthermore, as means for removing the liquid component contained in the image on the transfer member, there has been proposed a method of absorbing and removing the liquid component from the ink image by bringing a porous member into contact with the ink image without using thermal energy. (Patent Document 1). Another invention discloses a method of changing the position of an absorbing means for removing a liquid component contained in an ink image according to the type of recording medium determined by a recording medium determining means (Patent Reference 2).

JP 2009-213849 A JP 2006-306079 A

In order to remove the liquid component from the ink image, it is necessary to press the absorbing member against the recording medium on which the ink image is formed under appropriate pressure conditions. If the pressure is too low, the liquid component will not be sufficiently removed from the ink image. Conversely, if the pressure is too high, the ink image will be distorted or the coloring material will transfer to the absorbing member, resulting in image defects. Pressure fluctuations are caused by changes in the thickness of the recording medium, deformation of the recording medium and absorption member supporting means, thermal expansion, and the like. Therefore, the pressure must be controlled within an appropriate pressure range so as not to cause these problems.

Japanese Patent Application Laid-Open No. 2002-200002 includes a medium determination unit that determines the type of medium to be used, and changes the distance between the absorbing member and the recording medium according to the determined type of medium. However, this method requires a separate media determination sensor, and has problems such as excessive pressure being applied when multiple sheets of paper are fed. In addition, in the configuration provided with a heating mechanism, the distance between the absorbing member and the recording medium fluctuates due to thermal expansion in various parts of the apparatus, and unexpected pressure is applied.

The present invention has been made in view of such background art. An object of the present invention is to stabilize the level of pressure applied to a recording medium when removing liquid components from an ink image using a liquid absorbing member, and to continuously remove an appropriate amount of liquid components. and

The present invention comprises applying means for applying a liquid containing a coloring material to a recording medium to form an ink image, and a porous body for contacting the recording medium and absorbing at least part of the liquid from the ink image. a liquid absorbing member; pressing means for pressing a first surface formed of a porous body of the liquid absorbing member against a surface of the recording medium facing the first surface; and a conveying unit for conveying a recording medium. When the recording medium conveyed by the conveying unit is nipped by the liquid absorbing member, the ink image is brought into contact with the ink image by the pressing unit. An inkjet recording apparatus for pressing the first surface of the porous body against the surface of the recording medium, wherein the pressing means includes at least two pressing members having different hardness, A first pressing member and a second pressing member of at least two or more pressing members having different hardnesses are arranged on a side facing the transport unit, and the second pressing member is applied toward the transport unit. a fixing member arranged in the order of the member and the first pressing member, and fixing the supporting member so as to keep the distance between the supporting member supporting the two or more pressing members of the pressing means and the transport unit constant; The inkjet recording apparatus is characterized by further comprising:

According to the present invention, when removing liquid components from an ink image using a liquid absorbing member, it is possible to continuously remove an appropriate amount of liquid components.

1 is a schematic diagram showing an example of the configuration of a transfer-type inkjet recording apparatus according to an embodiment of the present invention; FIG. 1 is a schematic diagram showing an example of the configuration of a direct drawing type inkjet recording apparatus according to an embodiment of the present invention; FIG. 3 is a block diagram showing a control system for the entire apparatus in the inkjet printing apparatus shown in FIGS. 1 and 2; FIG. 2 is a block diagram of a printer control unit in the transfer-type inkjet recording apparatus shown in FIG. 1; FIG. 3 is a block diagram of a printer control section in the direct drawing type inkjet recording apparatus shown in FIG. 2; FIG. 1 is a perspective view of a first example of pressing means; FIG. It is the result of the structural analysis simulation regarding the first example of the pressing means. It is the result of the structural analysis simulation regarding the first example of the pressing means. 1 is a perspective view of a first example of pressing means; FIG. It is the result of the structural analysis simulation regarding the first example of the pressing means. It is the result of the structural analysis simulation regarding the first example of the pressing means.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to preferred embodiments.

An inkjet recording apparatus according to an embodiment will be described below with reference to the drawings.

The inkjet recording apparatus of the embodiment forms an ink image by ejecting ink onto a transfer body as an ejection receiving medium, and transfers the ink image after liquid absorption from the ink image by a liquid absorbing member to a recording medium. There is a recording device. Another example is an inkjet recording apparatus that forms an ink image on a recording medium such as paper or cloth as a medium to be ejected, and absorbs liquid from the ink image on the recording medium with a liquid absorbing member. In the present invention, the former ink jet recording apparatus is hereinafter referred to as a transfer type ink jet recording apparatus for convenience, and the latter ink jet recording apparatus is hereinafter referred to as a direct drawing type ink jet recording apparatus for convenience.

Each inkjet recording apparatus will be described below.

(Transfer type inkjet recording device)
FIG. 1 is a schematic diagram showing an example of the schematic configuration of a transfer-type inkjet recording apparatus 100 of this embodiment. This recording apparatus is a sheet-fed type inkjet recording apparatus that manufactures recorded matter by transferring an ink image onto a recording medium 108 via a transfer body 101 . In the present embodiment, the X direction, Y direction, and Z direction indicate the width direction (full length direction), depth direction, and height direction of the inkjet recording apparatus 100, respectively. The recording medium P is conveyed in the X direction.

As shown in FIG. 1, the transfer type inkjet recording apparatus 100 has a transfer body 101 supported by a support member 102 and a reaction liquid application device 103 that applies a reaction liquid that reacts with color ink onto the transfer body 101 . Furthermore, an ink applying device 104 is provided, which has an inkjet head for applying colored ink onto the transfer body 101 to which the reaction liquid has been applied, and forming an ink image, which is an ink image, on the transfer body. A liquid absorbing device 105 for absorbing a liquid component from the ink image on the transfer body, and a transfer pressure member 106 for transferring the ink image on the transfer body from which the liquid component has been removed onto a recording medium 108 such as paper. and Further, the transfer-type inkjet recording apparatus 100 may have a transfer body cleaning member 109 for cleaning the surface of the transfer body 101 after transfer, if necessary. Of course, the transfer body 101, the reaction liquid applying device 103, the inkjet head of the ink applying device 104, the liquid absorbing 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 member 101 rotates in the direction of arrow A in FIG. The rotation of the support member 102 causes the transfer member 101 to move. A reaction liquid applying device 103 applies a reaction liquid and an ink applying device 104 applies ink sequentially onto the moving transfer body 101 , forming an ink image on the transfer body 101 . The ink image formed on the transfer body 101 is moved by the movement of the transfer body 101 to a position where it comes into contact with the liquid absorbing member 105 a of the liquid absorbing device 105 .

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 member 101 is brought into 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 member. In this contact state, it is particularly preferable that the liquid absorbing member 105a is pressed against the transfer body 101 with a predetermined pressing force in order to effectively function the liquid absorbing member 105a.

Describing the removal of the liquid component from a different point of view, it can also be expressed as concentrating the ink forming the image formed on the transfer member. Concentrating the ink means that the liquid component contained in the ink is reduced, thereby increasing the content ratio of the solid content such as the coloring material and resin contained in the ink to the liquid component.

The ink image after liquid removal from which the liquid component has been removed is in a state in which the ink is more concentrated than the ink image before liquid removal. 108 is moved to the transfer station 111 in contact with the transfer station 111 . While the ink image after liquid removal is in contact with the recording medium 108 , the pressing member 106 presses the transfer body 101 to transfer the ink image onto the recording medium 108 . The post-transfer ink image transferred onto the recording medium 108 is a reverse image of the ink image before liquid removal and the ink image after liquid removal.

In the present embodiment, since the image is formed by applying the ink to the transfer body after the reaction liquid is applied, the reaction liquid does not react with the ink in the non-image area where the ink image is not formed. Remaining. In this apparatus, the liquid absorbing member 105a contacts not only the image but also the unreacted reaction liquid, and removes the liquid component of the reaction liquid as well.

Therefore, in the above description, the liquid component is described as being removed from the image, but the meaning is not limited to removing the liquid component only from the image, but at least the liquid component is removed from the image on the transfer body. It is used in the sense that it is good.

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

Examples of liquid components include water, organic solvents, and the like contained in ink and reaction liquids.

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

<Transfer>
The transfer member 101 has a surface layer including an image forming surface. Various materials such as resins and ceramics can be appropriately used as the member of the surface layer, but materials having a high compressive elastic modulus are preferable from the viewpoint of durability and the like. Specific examples include acrylic resins, acrylic silicone resins, fluorine-containing resins, condensates obtained by condensing hydrolyzable organosilicon compounds, and the like. In order to improve the wettability, transferability, etc. of the reaction liquid, it may be used after being subjected to surface treatment. Examples of surface treatment include flame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, active energy ray irradiation treatment, ozone treatment, surfactant treatment, and silane coupling treatment. A plurality of these may be combined. Also, the surface layer can be provided with an arbitrary surface shape.

Also, the transfer member preferably has a compression layer that has a function of absorbing pressure fluctuations. By providing the compression layer, the compression layer absorbs deformation and disperses local pressure fluctuations, so that good transferability can be maintained even during high-speed printing. Examples of the member of the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, and silicone rubber. It is preferable to add a predetermined amount of a vulcanizing agent, a vulcanization accelerator, etc. at the time of molding the rubber material, and further add a filler such as a foaming agent, hollow fine particles, or salt as necessary to make the rubber material porous. As a result, the bubble portion is compressed with a change in volume in response to various pressure fluctuations, so deformation in directions other than the direction of compression is small, and more stable transferability and durability can be obtained. Porous rubber materials include those having a continuous pore structure in which each pore is continuous with each other and those having 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.

Furthermore, the transfer body preferably has an elastic layer between the surface layer and the compression layer. Various materials such as resins and ceramics can be appropriately used as the member of the elastic layer. Various elastomer materials and rubber materials are preferably used in terms of processability and the like. Specific examples include fluorosilicone rubber, phenylsilicone rubber, fluororubber, chloroprene rubber, urethane rubber, nitrile rubber, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, and butadiene rubber. Also included are ethylene/propylene/butadiene copolymers, nitrile butadiene rubbers, and the like. In particular, silicone rubber, fluorosilicone rubber, and phenylsilicone rubber are preferable in terms of dimensional stability and durability because of their low compression set. In addition, the change in elastic modulus due to temperature is small, which is preferable in terms of transferability.

Various adhesives or double-sided tapes may be used between the layers (surface layer, elastic layer, compression layer) constituting the transfer member to fix and hold them. In addition, a reinforcing layer having a high compression modulus may be provided in order to suppress lateral stretching when attached to a device and to maintain stiffness. Moreover, it is good also considering a woven fabric as a reinforcement layer. The transfer member can be produced by arbitrarily combining layers made of the above materials.

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

<Support member>
A transfer body 101 is supported on a support member 102 . As a method for supporting the transfer member, 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 using the installation member.

The support member 102 is required to have a certain degree of structural strength from the viewpoints of transportation accuracy and durability. Metals, ceramics, resins, and the like are preferably used as materials for the supporting member. Among them, aluminum, iron, stainless steel, acetal resin, and epoxy resin are particularly preferable in order to reduce inertia during operation and improve control responsiveness in addition to rigidity and dimensional accuracy that can withstand pressure during transfer. Also, polyimide, polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, and alumina ceramics are preferably used. It is also preferable to use these in combination.

<Reaction liquid application device>
The inkjet recording apparatus of this embodiment has a reaction liquid applying device 103 that applies a reaction liquid to the transfer body 101 . The reaction liquid application device 103 of FIG. 1 has a reaction liquid storage section 103a that stores the reaction liquid, and reaction liquid deposition members 103b and 103c that apply the reaction liquid in the reaction liquid storage section 103a onto the transfer body 101. The case of rollers is shown.

The reaction liquid application device may be any device capable of applying the reaction liquid onto the medium to be ejected, and conventionally known various devices can be appropriately used. Specifically, a gravure offset roller, an inkjet head, a die coating device (die coater), a blade coating device (blade coater), and the like are included. Application of the reaction liquid by the reaction liquid application device may be performed before or after application of the ink, as long as the reaction liquid can be mixed (reacted) with the ink on the medium to be ejected. Preferably, the reaction liquid is applied before applying the ink. By applying the reaction liquid before applying the ink, during image recording by the inkjet method, bleeding occurs when adjacent applied inks are mixed together, and beading occurs when ink that hits earlier is attracted to ink that hits later. ding can also be suppressed.

<Reaction solution>
The reaction liquid contains a component that increases the viscosity of the ink (ink viscosity increasing component). Increasing the viscosity of the ink means that the coloring material, resin, etc., which are part of the composition that constitutes the ink, chemically reacts or physically adsorbs when they come into contact with the ink viscosity-increasing component. This includes cases where an increase in the viscosity of the ink as a whole is recognized. It also includes a case in which viscosity increases locally due to agglomeration of some of the components that make up the ink, such as the coloring material. This ink-viscosity-increasing component has the effect of reducing the fluidity of the ink and/or the ink composition on a medium to be ejected, thereby suppressing bleeding and beading during image formation with the ink. Known substances such as polyvalent metal ions, organic acids, cationic polymers, and porous fine particles can be used as such ink viscosity increasing components. Among them, polyvalent metal ions and organic acids are particularly suitable. In addition, it is also preferable to contain a plurality of types of ink viscosity-enhancing components. The content of the ink viscosity increasing component in the reaction liquid is preferably 5 mass % or more with respect to the total mass of the reaction liquid.

Examples of polyvalent metal ions 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⁺ . and trivalent metal ions.

Examples of organic acids include oxalic acid, polyacrylic acid, formic acid, acetic acid, propionic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, levulinic acid, succinic acid, glutaric acid, glutamic acid, and fumaric acid. , citric acid, tartaric acid, and lactic acid. Also included are pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, nicotinic acid, oxysuccinic acid, dioxysuccinic acid and the like.

The reaction liquid can contain an appropriate amount of water or a low-volatility organic solvent. The water used in this case is preferably deionized water by ion exchange or the like. Moreover, the organic solvent that can be used in the reaction solution applied to the present invention is not particularly limited, and known organic solvents can be used.

Further, the reaction liquid can be used by adding a surfactant or a viscosity modifier to appropriately adjust its surface tension and viscosity. Materials to be used are not particularly limited as long as they can coexist with the ink viscosity increasing component. Acetylene glycol ethylene oxide adducts ("Acetylenol E100", trade name manufactured by Kawaken Fine Chemicals Co., Ltd.), perfluoroalkyl ethylene oxide adducts ("Megafac F444", trade name manufactured by DIC Corporation), and the like.

<Ink application device>
The inkjet recording apparatus of this embodiment has an ink application 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 the liquid component is absorbed from the ink image by the liquid absorption device 105 .

<Ink application device>
In this embodiment, an inkjet head is used as an ink application device that applies ink. As an inkjet head, for example, an electro-thermal transducer causes film boiling in ink to form air bubbles to eject ink, an electro-mechanical transducer ejects ink, and an ink is ejected using static electricity. Examples include a form of discharging. In this embodiment, a known inkjet head can be used. Among them, from the viewpoint of high-speed and high-density printing, those using an electro-thermal converter are preferably used. For drawing, an image signal is received and the required amount of ink is applied to each position.

In this embodiment, the inkjet head is a full-line head extending in the Y direction, and nozzles are arranged in a range that covers the width of the image recording area of the maximum size recording medium that can be used. The inkjet head has an ink ejection surface with nozzles on its lower surface (on the transfer body 1 side), and the ink ejection surface faces the surface of the transfer body 1 with a minute gap (of the order of several millimeters). .

The amount of applied ink can be expressed in terms of image density (duty) or ink thickness. ² ). From the viewpoint of removing the liquid component in the ink, the maximum ink application amount in the image area is the ink application amount that is applied in an area of at least 5 mm ² or more in the area used as the information of the ejection receiving medium. show.

The ink applying device 104 may have a plurality of inkjet heads to apply each color ink onto the ejection receiving medium. For example, when yellow ink, magenta ink, cyan ink, and black ink are used to form respective color images, the ink application device should have four inkjet heads that respectively eject the four types of ink onto the ejection receiving medium. become. In that case, they are arranged side by side in the X direction.

Further, the ink application device may include an inkjet head that ejects a substantially transparent clear ink that does not contain a coloring material, or contains a coloring material in a very low proportion. This clear ink can be used together with the reaction liquid and the color inks to form an ink image. For example, this clear ink can be used to improve the glossiness of images. It is preferable to appropriately adjust the resin component to be blended and further control the discharge position of the clear ink so that the image after the transfer has a glossy feeling. Since it is desirable that the clear ink is on the surface layer side of the final printed material, the clear ink is applied to the transfer body 1 prior to the color ink in a transfer body type recording apparatus. Therefore, in the moving direction of the transfer body 1 facing the ink applying device 104, the inkjet head for clear ink can be arranged upstream from the inkjet head for color ink.

In addition to glossiness, it can be used to improve transferability of an image from the transfer body 1 to a recording medium. For example, the clear ink can be used as a transfer property improving liquid to be applied onto the transfer body 1 by including a component that develops stickiness more 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 upstream from the inkjet head for color ink. After the color ink is applied to the transfer body 101, clear ink is applied to the transfer body to which the color ink has been applied, so that the clear ink exists on the outermost surface of the ink image. When the ink image is transferred 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. easier to do.

<Ink>
Each component of the ink applied to this embodiment will be described.

(colorant)
A pigment or a mixture of a dye and a pigment can be used as the coloring material contained in the ink applied to this embodiment. The type of pigment that can be used as a coloring material is not particularly limited. Specific examples of pigments include inorganic pigments such as carbon black; and organic pigments such as azo-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, imidazolone-based, diketopyrrolopyrrole-based, and dioxazine-based pigments. One or more of these pigments may be used as necessary.

The type of dye that can be used as the coloring material is not particularly limited. Specific examples of dyes include direct dyes, acid dyes, basic dyes, disperse dyes, and food dyes, and dyes having anionic groups can be used. Specific examples of dye skeletons include azo skeletons, triphenylmethane skeletons, phthalocyanine skeletons, azaphthalocyanine skeletons, xanthene skeletons, and anthrapyridone skeletons.

The content of the pigment in the ink is preferably 0.5% by mass or more and 15.0% by mass or less, more preferably 1.0% by mass or more and 10.0% by mass or less, relative to the total mass of the ink. .

(dispersant)
As a dispersant for dispersing the pigment, a known dispersant used for inkjet ink can be used. Above all, in the aspect of the present embodiment, it is preferable to use a water-soluble dispersant having both a hydrophilic portion and a hydrophobic portion in its structure. In particular, a pigment dispersant comprising a resin obtained by copolymerizing at least a hydrophilic monomer and a hydrophobic monomer is preferably used. Each monomer used here is not particularly limited, and known monomers are preferably used. Specifically, hydrophobic monomers include styrene and other styrene derivatives, alkyl (meth)acrylates, benzyl (meth)acrylates, and the like. Examples of hydrophilic monomers include acrylic acid, methacrylic acid, and maleic acid.

The acid value of the dispersant is preferably 50 mgKOH/g or more and 550 mgKOH/g or less. Moreover, the weight average molecular weight of the dispersant is preferably 1,000 or more and 50,000 or less. The mass ratio of pigment and dispersant (pigment:dispersant) is preferably in the range of 1:0.1 to 1:3.

It is also suitable in the present embodiment to use a so-called self-dispersing pigment that is made dispersible by modifying the surface of the pigment itself without using a dispersant.

(resin fine particles)
The ink applied to this embodiment can be used by containing various kinds of fine particles that do not have a coloring material. Among them, fine resin particles are preferable because they are sometimes effective in improving image quality and fixability.

The material of the resin fine particles that can be used in this embodiment is not particularly limited, and known resins can be appropriately used. Specific examples include homopolymers such as polyolefin, polystyrene, polyurethane, polyester, polyether, polyurea, polyamide, polyvinyl alcohol, poly(meth)acrylic acid and its salts, polyalkyl(meth)acrylate, and polydiene. be done. Alternatively, a copolymer obtained by polymerizing a combination of a plurality of monomers for producing these homopolymers may be mentioned. The weight average molecular weight (Mw) of the resin is preferably in the range of 1,000 or more and 2,000,000 or less. The amount of the fine resin particles in the ink is preferably 1% by mass or more and 50% by mass or less, more preferably 2% by mass or more and 40% by mass or less, relative to the total mass of the ink.

Furthermore, in the aspect of the present embodiment, it is preferable to use a resin fine particle dispersion in which the resin fine particles are dispersed in a liquid. The method of dispersion is not particularly limited, but a so-called self-dispersing resin fine particle dispersion in which a resin obtained by homopolymerizing or copolymerizing a monomer having a dissociable group is used is suitable. The dissociative group includes carboxyl group, sulfonic acid group, phosphoric acid group and the like, and the monomer having the dissociative group includes acrylic acid, methacrylic acid and the like. Also, a so-called emulsified dispersion type resin fine particle dispersion in which resin fine particles are dispersed with an emulsifier can also be suitably used in the present embodiment. As the emulsifier referred to herein, a known surfactant is preferable regardless of whether it has a low molecular weight or a high molecular weight. The surfactant is preferably a nonionic surfactant or a surfactant having the same electric charge as the fine resin particles.

The fine resin particle dispersion used in the aspect of the present embodiment preferably has a dispersed particle size of 10 nm or more and 1000 nm or less, and more preferably has a dispersed particle size of 100 nm or more and 500 nm or less.

It is also preferable to add various additives for stabilization when preparing the fine resin particle dispersion used in the aspect of the present embodiment. Examples of the additive include n-hexadecane, dodecyl methacrylate, stearyl methacrylate, chlorobenzene, dodecyl mercaptan, blue dye (bluing agent), polymethyl methacrylate and the like.

(Surfactant)
The ink that can be used in this embodiment may contain a surfactant. Specific examples of surfactants include acetylene glycol ethylene oxide adducts (acetylenol E100, manufactured by Kawaken Fine Chemicals Co., Ltd.) and the like. The amount of surfactant in the ink is preferably 0.01% by mass or more and 5.0% by mass or less with respect to the total mass of the ink.

(Water and water-soluble organic solvent)
The ink used in this embodiment can contain water and/or a water-soluble organic solvent as a solvent. The water is preferably deionized water such as by ion exchange. Also, the content of water in the ink is preferably 30% by mass or more and 97% by mass or less with respect to the total mass of the ink.

The type of water-soluble organic solvent to be used is not particularly limited, and any known organic solvent can be used. Specific examples include glycerin, diethylene glycol, polyethylene glycol, polypropylene glycol, ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, and thiodiglycol. Also included are hexylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, 2-pyrrolidone, ethanol, methanol, and the like. Of course, two or more kinds selected from these can be mixed and used.

Moreover, the content of the water-soluble organic solvent in the ink is preferably 3% by mass or more and 70% by mass or less with respect to the total mass of the ink.

(Other additives)
Ink that can be used in the present embodiment includes pH adjusters, rust inhibitors, preservatives, anti-mold agents, antioxidants, anti-reduction agents, water-soluble resins and their neutralizers, in addition to the above components, if necessary. It may contain various additives such as agents and viscosity modifiers.

<Liquid absorber>
In this embodiment, the liquid absorbing device 105 has a liquid absorbing member 105 a and a pressing member 105 b for liquid absorption that presses the liquid absorbing member 105 a against the ink image on the transfer body 101 . There are no particular restrictions on the shapes of the liquid absorbing member 105a and the pressing member 105b. For example, as shown in FIG. 1, the pressing member 105b is cylindrical, the liquid absorbing member 105a is belt-shaped, and the belt-shaped liquid absorbing member 105a is pressed against the transfer member 101 by the cylindrical pressing member 105b. It may be a configuration. The pressing member 105b has a cylindrical shape, and the liquid absorbing member 105a has a cylindrical shape formed on the peripheral surface of the cylindrical pressing member 105b. may be pressed against the transfer body.

In this embodiment, the liquid absorbing member 105a is preferably belt-shaped in consideration of the space in the inkjet recording apparatus.

Further, the liquid absorbing device 105 having such a belt-shaped liquid absorbing member 105a may have a stretching member for stretching the liquid absorbing member 105a. In FIG. 1, 105c is a tension roller as a tension member. In FIG. 1, the pressing member 105b is also a roller member that rotates like the tension roller, but it is not limited to this.

In the liquid absorbing device 105, the liquid absorbing member 105a having a porous material is pressed against the ink image by the pressing member 105b to make the liquid absorbing member 105a absorb the liquid component contained in the ink image. Decrease. As a method for reducing the liquid component in the ink image, in addition to the present method of contacting the liquid absorbing member, various conventional methods such as heating, blowing low-humidity air, reducing pressure, etc. may be combined. Further, these methods may be applied to the ink image after liquid removal from which the liquid component has been reduced to further reduce the liquid component.

<Liquid absorbing member>
In this embodiment, at least part of the liquid component is removed from the ink image before the liquid is removed by being brought into contact with a liquid absorbing member having a porous material to absorb the liquid component, thereby reducing the content of the liquid component in the ink image. Let The contact surface of the liquid absorbing member with the ink image is defined as a first surface, and the porous body is arranged on the first surface. The liquid absorbing member having such a porous material moves in conjunction with the movement of the ejection receiving medium, contacts the ink image, and then re-contacts another ink image before liquid removal at a predetermined cycle. It is preferable to have a shape capable of absorbing liquid. For example, shapes such as an endless belt shape and a drum shape can be mentioned.

(Porous body)
The porous body of the liquid absorbing member according to this embodiment preferably has a smaller average pore size on the first surface side than the average pore size on the second surface side facing the first surface. In order to prevent the coloring material in the ink from adhering to the porous body, the pore size is preferably small. preferable. In the present embodiment, the average pore size means the average diameter on the surface of the first surface or the second surface, and is measured by known means such as mercury porosimetry, nitrogen adsorption, SEM image observation, etc. It is possible.

In addition, it is preferable to reduce the thickness of the porous body in order to obtain uniformly high air permeability. The air permeability can be indicated by the Gurley value specified in JIS P8117, and the Gurley value is preferably 10 seconds or less.

However, if the porous body is made thin, it may not be possible to secure a sufficient capacity for absorbing the liquid component, so it is possible to make the porous body a multi-layered structure. In the liquid absorbing member, the layer in contact with the ink image may be porous, and the layer not in contact with the ink image may not be porous.

Next, an embodiment in which the porous body has a multi-layer structure will be described. Here, the first layer on the side in contact with the ink image, and the layer laminated on the surface opposite to the contact surface with the ink image of the first layer will be described as the second layer. Furthermore, the structure of multiple layers is also described in order of lamination from the first layer. In addition, in this specification, the first layer may be referred to as an "absorbent layer", and the layers subsequent to the second layer may be referred to as a "support layer".

In this embodiment, the material of the first layer is not particularly limited, and both a hydrophilic material with a contact angle to water of less than 90° and a water-repellent material with a contact angle of 90° or more are used. be able to.

The hydrophilic material is preferably selected from single materials such as cellulose and polyacrylamide, composite materials thereof, and the like. Moreover, the surface of the following water-repellent material can be hydrophilized before use. The hydrophilization treatment includes methods such as sputter etching, radiation or H2O ion irradiation, and excimer (ultraviolet) laser light irradiation.

In the case of hydrophilic materials, it is more preferable that the contact angle with water is 60° or less. Hydrophilic materials have the effect of sucking up liquids, especially water, due to capillary forces.

On the other hand, the material of the first layer is preferably a water-repellent material with a low surface free energy, particularly a fluororesin, in order to suppress the adhesion of the coloring material and to improve the cleanability. Specific examples of the fluororesin include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and perfluoroalkoxy fluororesin (PFA). be done. Further, ethylene tetrafluoride/propylene hexafluoride copolymer (FEP), ethylene/tetrafluoroethylene copolymer (ETFE), ethylene/chlorotrifluoroethylene copolymer (ECTFE) and the like are included. One or two or more of these resins may be used as necessary, and a structure in which a plurality of films are laminated in the first layer may be employed. In the case of a water-repellent material, there is almost no effect of sucking up the liquid by capillary force, and it may take time to suck up the liquid when it comes into contact with the image for the first time. Therefore, it is preferable to impregnate the first layer with a liquid having a contact angle of less than 90° with the first layer. This liquid can be impregnated into the first layer by applying it from the first surface of the liquid absorbing member. This liquid is preferably prepared by mixing water with a surfactant or a liquid having a low contact angle with the first layer.

In this embodiment, the film thickness of the first layer is preferably 50 μm or less. The film thickness is more preferably 30 μm or less. In the examples of the present embodiment, the film thickness was obtained by measuring the film thickness at arbitrary 10 points with a linear micrometer OMV_25 (manufactured by Mitutoyo) and calculating the average value.

The first layer can be produced by a known method for producing a thin porous membrane. For example, it can be obtained by forming a sheet of a resin material by extrusion molding or the like, and then stretching it to a predetermined thickness. Alternatively, a porous film can be obtained by adding a plasticizer such as paraffin to the material during extrusion molding and removing the plasticizer by heating or the like during stretching. The pore size can be adjusted by appropriately adjusting the amount of the plasticizer to be added, the draw ratio, and the like.

[Second layer]
In this embodiment, the second layer is preferably a breathable layer. Such a layer may be a non-woven fabric of resin fibers or a woven fabric. The material of the second layer is not particularly limited, but the contact angle with the first liquid is equal to or greater than that of the first layer so that the absorbed liquid does not flow back to the first layer side. Low material is preferred. Specific examples include polyolefins (polyethylene (PE), polypropylene (PP), etc.), polyamides such as polyurethane and nylon, and polyesters (polyethylene terephthalate (PET), etc.). Also, it is preferably selected from a single material such as polysulfone (PSF), or a composite material thereof. Also, the second layer preferably has a larger pore size than the first layer.

[Third layer]
In this embodiment, the porous body having a multilayer structure may have a structure of three or more layers, and is not limited. From the standpoint of rigidity, nonwoven fabrics are preferable for the layers after the third layer (also referred to as the third layer). The material used is the same as that of the second layer.

[Other materials]
The liquid absorbing member may have a reinforcing member that reinforces the side surface of the liquid absorbing member, in addition to the porous body having the laminated structure. Moreover, it may have a joining member for connecting the longitudinal ends of the long sheet-shaped porous body to form a belt-shaped member. As such a material, a non-porous tape material or the like can be used, and it may be arranged at a position or period not in contact with the image.

[Method for producing porous body]
A method for laminating the first layer and the second layer to form a porous body is not particularly limited. They may be simply overlapped or adhered to each other using methods such as adhesive lamination or heat lamination. Thermal lamination is preferred in this embodiment from the viewpoint of breathability. Further, for example, a part of the first layer or the second layer may be melted by heating for adhesion lamination. Alternatively, a fusing material such as hot-melt powder may be interposed between the first layer and the second layer, and the layers may be adhered and laminated together by heating. When the third layer or more are laminated, they may be laminated at once or sequentially, and the order of lamination is appropriately selected.

In the heating step, a lamination method is preferred in which the porous body is heated while being pressed between heated rollers.

Various conditions and configurations of the liquid absorption device 105 will be described in detail below.

(Preprocessing)
In this embodiment, before the liquid absorbing member 105a having a porous body is brought into contact with the ink image, pretreatment is performed by pretreatment means (not shown in FIGS. 1 and 2) for applying a treatment liquid to the liquid absorbing member. is preferred. The treatment liquid used in this embodiment preferably contains water and a water-soluble organic solvent. The water is preferably deionized water such as by ion exchange. The type of water-soluble organic solvent is not particularly limited, and any known organic solvent such as ethanol or isopropyl alcohol can be used. In the pretreatment of the liquid absorbing member used in the present embodiment, the applying method is not particularly limited, but immersion or droplet dropping is preferable.

(pressurization conditions)
If the pressure of the liquid absorbing member when contacting the ink image on the transfer member is 0.2 MPa or more, the liquid component in the ink image can be solid-liquid separated in a short time, and the liquid component can be removed from the ink image. It is preferable because it can be removed. Further, when the pressure of the liquid absorbing member is 0.4 MPa or less, the liquid component can be removed without the coloring material in the ink image adhering to the liquid absorbing member. Therefore, it is preferable to use the pressure of the liquid absorbing member within the range of 0.2 MPa to 0.4 MPa. The pressure of the liquid absorbing member in this specification indicates the nip pressure between the medium to be discharged and the liquid absorbing member, and is measured by a surface pressure distribution measuring instrument (“I-SCAN” manufactured by Nitta Co., Ltd.). is used to measure the surface pressure, and the weight in the pressurized area is divided by the area to calculate the value.

(action time)
The action time for bringing the liquid absorbing member 105a into contact with the ink image is preferably within 50 ms in order to further prevent 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 direction of movement of the medium to be ejected in the surface pressure measurement described above by the speed of movement of the medium to be ejected. This action time is hereinafter referred to as liquid absorption nip time.

(Pressing member)
The transfer body undergoes permanent deformation and becomes thin due to long-term use. Also, when the transfer body is heated, the thickness increases due to the transfer body and thermal expansion. If there is such a change, the distance between the transfer member and the liquid absorbing member will change, and the pressure range of the liquid absorbing member will be outside the preferred range, and sufficient liquid absorbing performance cannot be exhibited. In order to keep the pressure of the liquid absorbing member within an appropriate range even when the distance between the transfer body and the absorbing member varies, it is effective to provide the pressing member with an elastic function. Although there are various actual configurations, examples include a configuration in which the pressing member on the side in contact with the liquid absorbing member is made of rubber, and a configuration in which the pressing member in contact with the liquid absorbing member is supported by an elastic body such as a spring or rubber. be done.

FIG. 6 is an example of the pressing means. The pressing means 600 has a structure in which rubber 601 is laminated on a metal roller 602 . The ends of the metal roller 602 are supported by bearings 603a and 603b, which are supporting members of the pressing means 600. As shown in FIG. The bearing 603a is connected to the pressing fixing member 604a, and the bearing 603b is connected to the pressing fixing member 604b. The relative positions of the pressing means 600 and the transport unit 607 in the z-direction are fixed by pressing fixing members 604a and 604b. Then, the pressing means 600 presses the liquid absorbing member 605 against the recording medium 606 conveyed by the conveying unit 607 to remove the liquid from the ink image. By fixing the bearings 603a and 604b by the pressing fixing members 604a and 604b, the range of displacement of the rubber 601 accompanying the deformation of the transfer body is regulated.

A contact analysis was performed on the structure shown in FIG. 6 using numerical simulation for structural analysis. The outer shape of the pressing means 600 is 80 mm, and the thickness of the rubber 601 is 5 mm. The recording medium 606 is used by modeling the deformation characteristics of the transfer body used in this embodiment. In the analysis, rubber 601 pressing fixing member 604
The elastic system coefficient E was varied, and the contact pressure and width with respect to the pushing amount by the pressing and fixing member 604 were evaluated assuming that the displacement in the state where the liquid absorbing member 605 started contacting the recording medium 606 was 0 mm.

FIG. 7 shows the relationship between the displacement (position) of the pressing fixing member 604 on the horizontal axis and the average contact pressure on the recording medium 606 on the vertical axis. The smaller the elastic modulus E of the rubber, the smaller the inclination, and the larger the permissible fluctuation range Δz allowed for the displacement from 0.2 MPa to 0.4 MPa, which is the preferred pressure range.

FIG. 8 shows the relationship between the elastic modulus E, the allowable variation width Δz (left vertical axis), and the maximum nip width dmax (right vertical axis) at the maximum allowable pressure (0.4 MPa). It can be confirmed that the smaller the modulus of elasticity, the larger the allowable fluctuation width Δz and the larger the maximum nip width dmax at that time. A small elastic modulus is desirable for use in a suitable pressure range, but if the nip width is too wide, the possibility of the coloring material in the ink image adhering to the liquid absorbing member increases, so the elastic modulus is unnecessarily small. is not desirable. For example, if the nip width exceeds 20 mm when the moving linear velocity of the liquid absorbing member and the transport unit is 0.4 m/s, the action time for bringing the liquid absorbing member into contact with the ink image exceeds 50 ms. In order to prevent the coloring material from adhering to the liquid absorbing member in this way, it is necessary to design the elastic modulus of the rubber and the conveying speed within a range in which the action time does not exceed 50 ms.

FIG. 9 shows an example of another form of pressing means. The pressing means 900 has a structure in which a rubber 902 and a base metal member 903 as a supporting member are laminated on a pressing metal member 901 . The pressing metal member 901 preferably has a configuration capable of highly absorbing and removing liquid from the ink image without disturbing the image. Moreover, it is desirable that the pressing metal member 901 be configured to move only in one direction when the rubber 902 is deformed. If the direction of displacement is not restricted, the contact angle of the pressing metal member 901 to the recording medium 906 becomes unstable due to the transportation of the recording medium 906 and the liquid absorbing member 905 . If the elastic modulus of the rubber is large, the contact angle fluctuation is small, but if the elastic modulus of the rubber is small, the contact angle tends to become unstable. It is preferable to have a configuration that In this embodiment, a slide bush (not shown) is used to constrain the displacement direction of the pressing metal member 901 in the z-direction in order to avoid the contact angle from becoming unstable. Note that the constraining direction is not limited to the z-direction in the drawing, and a direction inclined from the z-axis may be used as long as it is constrained in one direction. The base metal member 903 is connected with the press fixing member 904 . By controlling the spatial arrangement of the pressing means 900 in the z-direction with the pressing and fixing member 904, the liquid absorbing member 905 is pressed against the recording medium 906 conveyed by the conveying unit 907 to remove the liquid from the ink image. By fixing the base metal member 903 by the pressing fixing member 904, the range of displacement of the rubber 902 accompanying the deformation of the transfer member is regulated. It is also possible to use a spring instead of the rubber 902 .

FIG. 10 shows the relationship between the displacement (position) of the press fixing member 904 and the average contact pressure, as in FIG. The smaller the elastic modulus E of the rubber, the smaller the inclination, and the larger the permissible fluctuation range Δz allowed for the displacement from 0.2 MPa to 0.4 MPa, which is the preferred pressure range.

FIG. 11 shows the relationship between the allowable fluctuation width Δz (left vertical axis) with respect to the elastic modulus E of the rubber 902 and the maximum nip width dmax (right vertical axis) at the maximum allowable pressure (0.4 MPa), as in FIG. . As in FIG. 8, the allowable fluctuation width Δz increases as the elastic modulus decreases, but the maximum nip width dmax is substantially constant. That is, unlike the configuration of FIG. 6, there is a feature that the nip width does not fluctuate even if rubber with a small elastic modulus is used.

In this manner, the liquid component is absorbed on the transfer body 101, and an ink image with a reduced liquid component is formed. The ink image from which the liquid has been removed is then transferred onto the recording medium 108 in the transfer section 111 . The apparatus configuration and conditions for transfer will be described.

<Pressing member for transfer>
In this 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 bringing the pressure member 106 for transfer into contact with the recording medium 108 . By removing the liquid component contained in the ink image on the transfer body 101 and then transferring it 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 degree of structural strength from the viewpoint of conveying accuracy of the recording medium 108 and durability. Metal, ceramic, resin, or the like is preferably used as the material of the pressing member 106 . In particular, in order to reduce inertia during operation and improve control responsiveness, in addition to rigidity and dimensional accuracy that can withstand pressure during transfer, aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, Polyethylene and polyethylene terephthalate are preferably used. Also, 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 during which the pressing member 106 presses the transfer body in order to transfer the ink image on the transfer body 101 from which the liquid has been removed to the recording medium 108 . However, the time is preferably 5 ms or more and 100 ms or less in order to ensure good transfer without impairing the durability of the transfer body. The pressing time in this embodiment indicates the time during which the recording medium 108 and the transfer body 101 are in contact, and is measured using a surface pressure distribution measuring device ("I-SCAN" manufactured by Nitta Co., Ltd.). A value was calculated by measuring the surface pressure on the pressurized area and dividing the length of the pressurized area in the conveying direction by the conveying speed.

Further, the pressure with which the pressing member 106 presses the transfer body 101 to transfer the ink image on the transfer body 101 after removing the liquid onto the recording medium 108 is not particularly limited. Do not impair the endurance of the body. For this reason, the pressure is preferably 9.8 N/cm ² (1 kg/cm ² ) or more and 294.2 N/cm ² (30 kg/cm ² ) or less. 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 instrument, and the load in the pressurized area is divided by the area. value is calculated.

The temperature at which the pressing member 106 presses the transfer body 101 in order to transfer the ink image on the transfer body 101 after removing the liquid onto the recording medium 108 is not particularly limited, but it depends on the resin component contained in the ink. It is preferably above the glass transition point or above the softening point. In addition, it is preferable to provide heating means for heating the second image on the transfer body 101 , the transfer body 101 and the recording medium 108 .

Although the shape of the transfer means 106 is not particularly limited, for example, a roller shape can be used.

<Recording medium and recording medium conveying device>
In this embodiment, the recording medium 108 is not particularly limited, and any known recording medium can be used. Examples of the recording medium include a long object wound into a roll or a sheet cut into a predetermined size. Materials include paper, plastic film, wood board, cardboard, and metal film.

In FIG. 1, the recording medium conveying device 107 for conveying the recording medium 108 is composed of the recording medium feeding roller 107a and the recording medium take-up roller 107b. is not limited to

<Control system>
The transfer-type inkjet recording apparatus in this embodiment has a control system that controls each device. FIG. 3 is a block diagram showing a control system for the entire apparatus in the transfer type ink jet recording apparatus shown in FIG.

In FIG. 3, reference numeral 301 denotes a print data generation unit such as an external print server; 302, an operation control unit such as an operation panel; and 303, a printer control unit for executing a printing process. Also, 304 is a recording medium conveyance control unit for conveying a recording medium, and 305 is an inkjet device for printing.

FIG. 4 is a block diagram of a printer control section in the transfer type ink jet recording apparatus of FIG.

A CPU 401 controls the entire printer, a ROM 402 stores a control program for the CPU 401, and a RAM 403 executes the program. Reference numeral 404 denotes an application-specific integrated circuit (ASIC) containing a network controller, a serial IF controller, a head data generation controller, a motor controller, and the like. Reference numeral 405 denotes a liquid absorbing member transport control unit for driving a liquid absorbing member transport motor 406, which is command-controlled from the ASIC 404 via a serial IF. Reference numeral 407 denotes a transfer member drive control unit for driving a transfer member drive motor 408, which is similarly command-controlled from the ASIC 404 via the serial IF. A head control unit 409 generates final ejection data and drive voltage for the inkjet device 305 .

(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 ink jet recording apparatus, an ejection receiving medium is a recording medium on which an image is to be formed.

FIG. 2 is a schematic diagram showing an example of a schematic configuration of a direct drawing type inkjet recording apparatus 200 according to this embodiment. Unlike the above-described transfer type inkjet recording apparatus, the direct drawing type inkjet recording apparatus does not have the transfer member 101, the support member 102, and the transfer member cleaning member 109, and forms an image on the recording medium 208. It has the same means as the transfer type inkjet recording device. A reaction liquid applying device 203 for applying the reaction liquid to the recording medium 208 and an ink applying device 204 for applying ink to the recording medium 208 have the same configuration as that of the transfer type inkjet recording apparatus. The liquid absorbing device 205, which absorbs the liquid component contained in the ink image by means of the liquid absorbing member 205a in contact with the ink image on the recording medium 208, also has the same configuration as that of the transfer-type inkjet recording apparatus, and the description thereof is omitted. do.

In the direct drawing type inkjet recording apparatus of this embodiment, the liquid absorbing device 205 has a liquid absorbing member 205a and a pressure member 205b for liquid absorption that presses the liquid absorbing member 205a against the ink image on the recording medium 208. . On the opposite side of the recording medium 208 to the liquid absorbing member 205, there is a conveying unit 209 that clamps and conveys the recording medium 208. As shown in FIG. The conveying unit 209 is a metal roller with an outer diameter of 100 mm, and is rotated by a driving source (not shown). The shapes of the liquid absorbing member 205a and the pressing member 205b are not particularly limited, and the same shapes as those of the liquid absorbing member and pressing member that can be used in the transfer type ink jet recording apparatus can be used. Further, the liquid absorbing device 205 may have a stretching member for stretching the liquid absorbing member. In FIG. 2, 205c, 205d, 205e, 205f and 205g are tension rollers as tension members. The number of tension rollers is not limited to five in FIG. 4, and a necessary number may be arranged according to the design of the apparatus. Further, an ink application unit that applies ink to the recording medium 208 by the ink application device 204 may be provided.

<Recording medium conveying device>
In the direct drawing type inkjet recording apparatus of this embodiment, the recording medium conveying device 207 is not particularly limited, and a known conveying means in a direct drawing type inkjet recording apparatus can be used. As an example, as shown in FIG. 2, there is a recording medium conveying device having a recording medium feeding roller 207a, a recording medium take-up roller 207b, and conveying rollers 207c, 207d, 207e, and 207f for conveying the recording medium.

<Control system>
The direct drawing type ink jet recording apparatus in this embodiment has a control system for controlling each device. A block diagram showing the control system of the entire apparatus in the direct drawing type ink jet recording apparatus shown in FIG. 2 is as shown in FIG. 3, like the transfer type ink jet recording apparatus shown in FIG.

FIG. 5 is a block diagram of a printer control section in the direct drawing type ink jet recording apparatus of FIG. The block diagram of the printer control section in the transfer type ink jet recording apparatus in FIG.

That is, 501 is a CPU for controlling the entire printer, 502 is a ROM for storing control programs for the CPU, and 503 is a RAM for executing the programs. An ASIC 504 incorporates a network controller, a serial IF controller, a head data generation controller, a motor controller, and the like. Reference numeral 505 denotes a liquid absorbing member transport control unit for driving a liquid absorbing member transport motor 506, which is command-controlled from the ASIC 504 via a serial IF. A head control unit 509 generates final ejection data and drive voltage for the inkjet device 305 .

EXAMPLES Hereinafter, the present embodiment will be described in further detail using examples and comparative examples. The present invention is by no means limited by the following examples, as long as the gist thereof is not exceeded. In the description of the following examples, "parts" are based on mass unless otherwise specified.

(Example 1)
In this example, the transfer type ink jet recording apparatus shown in FIG. 1 was used. A transfer body 101 is fixed to a support member 102 with an adhesive. A sheet obtained by coating a PET sheet having a thickness of 0.5 mm with a silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE12) to a thickness of 0.3 mm was used as an elastic layer of the transfer member. As a heat insulating layer between the support member 102 and the elastic body, a 0.5 mm-thick foamed silicone rubber containing air bubbles was used as the lower layer of the elastic layer. Further, glycidoxypropyltriethoxysilane and methyltriethoxysilane were mixed at a molar ratio of 1:1, and a mixture of a condensate obtained by heating under reflux and a photocationic polymerization initiator (manufactured by ADEKA, trade name: SP150) was prepared. bottom. 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. Then, a film is formed by UV irradiation (high-pressure mercury lamp, cumulative exposure amount 5000 mJ/cm ² ) and thermal curing (150° C. for 2 hours) to form a transfer body 101 having a surface layer with a thickness of 0.5 μm formed on the elastic body. made. In this configuration, a double-faced tape is used to hold the transfer body 101 between the transfer body 101 and the support member 102, although illustration is omitted for simplicity of explanation. A double-faced tape was also used between the elastic layer and the heat insulating layer of the transfer body 101 to hold the elastic layer.

The reaction liquid applied by the reaction liquid applying device 103 had the following composition, and the applied amount was 1 g/m ² .
・Levulinic acid: 40.0 parts ・Glycerin: 5.0 parts ・Megafac F444 (trade name): 1.0 parts (surfactant, manufactured by DIC)
• Ion-exchanged water: 54.0 parts Ink was prepared as follows.

<Ink preparation>
<Preparation of resin particles>
18.0 parts of butyl methacrylate and 2.0 of polymerization initiator (2,2'-azobis(2-methylbutyronitrile)) are added to a four-necked flask equipped with a stirrer, a reflux condenser, and a nitrogen gas inlet tube. and 2.0 parts of n-hexadecane. Then, nitrogen gas was introduced into the reaction system and stirred for 0.5 hour. Into this flask, 78.0 parts of a 6.0% aqueous solution of an emulsifier (trade name: NIKKOL BC15, manufactured by Nikko Chemicals) was added dropwise and stirred for 0.5 hour. Then, the mixture was emulsified by applying ultrasonic waves for 3 hours using an ultrasonic irradiation machine. After that, a 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 content of resin particles 1 (solid content) of 20.0%. bottom.

<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 equimolar acid value, and an appropriate amount of pure water is added to prepare an aqueous solution of resin 1 having a resin (solid content) content of 20.0%. was prepared.

(Preparation of pigment dispersion)
10.0 parts of a 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 zirconia beads having a diameter of 0.3 mm were placed in a batch-type vertical sand mill (manufactured by Imex) and dispersed for 5 hours while cooling with water. Thereafter, centrifugal separation is performed to remove coarse particles, and pressure filtration is performed through a cellulose acetate filter (manufactured by Advantec) with 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 with a content of 3.0% was prepared.

(Ink preparation)
After each component shown below was mixed and sufficiently stirred, pressure filtration was performed with a cellulose acetate filter (manufactured by Advantec) having a pore size of 3.0 μm to prepare each ink. Acetylenol E100 is a surfactant manufactured by Kawaken Fine Chemicals.

(Composition of ink)
・Pigment dispersion liquid K: 20.0% by mass
Aqueous dispersion of resin particles 1: 50.0% by mass
・ Aqueous solution of resin 1: 5.0% by mass
・Glycerin: 5.0% by mass
・Diethylene glycol: 7.0% by mass
・Acetylenol E100: 0.5% by mass
・Pure: 12.5% by mass
As the ink application device 104, an inkjet device having an inkjet head of a type that uses an electro-thermal conversion element to eject ink in an on-demand system was used, and the amount of ink applied was 20 g/m ² .

<Pressing Means, Pressing Control Means>
The pressing means and pressing member used in this embodiment are those shown in FIG. The pressing means 600 has an outer diameter of 80 mm, a rubber thickness of 5 mm, and an elastic modulus of 2 MPa. The initial displacement z of the pressing means by the pressing control means was set to z=0.52 mm so that the average pressure P was 0.3 MPa. Here, the displacement z relates to the displacement when the pressing means 600 is moved. Let z>0. In this embodiment, the position before the start of the printing operation is used as a reference, and the contact start displacement between the recording medium 606 and the liquid absorbing member 605 is set to z=0.

In order to heat the ink image on the transfer body 101 from which the liquid has been removed to a temperature above the softening point of the resin component contained in the ink, the ink image contacts the liquid absorbing member 105 until it contacts the recording medium 108. , heating with an infrared lamp was performed (not shown). The heated transfer body 101 reaches a temperature of about 120° C. just before it contacts the recording medium 108, and is operated at an average temperature of about 60 to 100° C. per revolution. The heated transfer body becomes thicker by about 0.14 mm due to thermal expansion than in the room temperature state before operation, and the average contact pressure P of the pressing means 600 increases by the thermal expansion. In addition, the transfer member 101 undergoes permanent deformation due to long-term use, the thickness is reduced by a maximum of about 0.15 mm during the designed service life, and the average contact pressure is lower than the initially set value. That is, the thickness of the transfer body 101 increases by 0.14 mm due to thermal expansion in the initial period of use, and the thickness decreases by 0.1 mm due to permanent deformation and thermal expansion during long-term use. There will be an average contact pressure change when changing by 0.15 mm. In order to achieve good liquid absorption characteristics, it is necessary to keep the average contact pressure within the preferred pressure range as shown in FIG. 7 even when the displacement z varies by 0.15 mm. Referring to FIG. 8, when the elastic modulus of the rubber corresponding to this configuration is 2 MPa, the allowable variation range is Δz=0.3 mm, and even if thermal expansion and permanent deformation of the transfer body 101 occur, the preferable pressure range (0 .2 to 0.4 MPa).

(Comparative example 1)
As Comparative Example 1 with respect to Example 1, a case where a metal roller having an outer diameter of 80 mm is used as the pressing means 600 is shown. It should be noted that the configuration of the pressing means 600 is the same as that of the first embodiment. The displacement of the pressing member was set to z=0.18 mm and the average contact pressure was set to 0.3 MPa in the room temperature state before the start of operation. From FIG. 7, the allowable fluctuation width of the metal roller structure (corresponding to rubber elastic modulus E=∞) of this comparative example is Δz=0.11, and the thickness fluctuation width, which is the sum of thermal expansion and permanent deformation of the transfer member, is 0.11. 14 mm cannot be absorbed. When the transfer body is not permanently strained, the average contact pressure becomes 0.42 MPa due to thermal expansion, and the coloring material in the ink image adheres to the liquid absorbing member to disturb the image. In addition, due to long-term use, permanent deformation occurred in the transfer member, resulting in an average contact pressure of 0.18 MPa, resulting in insufficient liquid absorption from the ink image.

(Example 2)
<Pressing Means, Pressing Control Means>
The configuration of this embodiment is generally the same except for the pressing means and the pressing control means. The pressing means and pressing member used in this embodiment are those shown in FIG. The elastic modulus of the rubber 902 is 5 MPa, and the size is 25 mm in the x direction and 20 mm in the z direction. It was made to have a uniform cross section except for the bush (not shown) portion. The displacement of the pressing metal member 901 is restricted in the z-axis direction by a slide bush. The initial displacement z of the pressing means by the pressing control means was set to z=0.38 mm so that the average pressure P was 0.3 MPa. Here, the displacement z relates to the displacement when the pressing means 900 is moved. Let z>0. Also in this embodiment, the position before the start of the printing operation is used as a reference, and the contact start displacement between the recording medium 906 and the liquid absorbing member 905 is set to z=0.

Also in this embodiment, the thickness of the transfer member 101 varies by 0.15 mm due to thermal expansion and permanent deformation. Referring to FIG. 10, when the elastic modulus of the rubber corresponding to this configuration is 5 MPa, the allowable fluctuation range is Δz=0.34 mm, and even if thermal expansion and permanent deformation of the transfer body 101 occur, the preferable pressure range (0 .2 to 0.4 MPa).

(Comparative example 2)
As Comparative Example 2 with respect to Example 2, a case where the rubber 902 of the pressing means 900 is made of metal and the pressing metal member 901 and the base metal member 903 are integrally formed will be shown. The configuration other than the configuration of the pressing means 900 is the same as that of the second embodiment. In the room temperature state before starting the operation, the displacement of the pressing member was set to z=0.21 mm, and the average contact pressure was set to 0.3 MPa. From FIG. 10, the allowable variation width of the configuration of this comparative example (equivalent to rubber elastic modulus E=∞) is Δz=0.14, and the thickness variation width, which is the sum of the thermal expansion and permanent deformation of the transfer body, is 0.15. cannot be absorbed. When the transfer body is not permanently strained, the average contact pressure becomes 0.52 MPa due to thermal expansion, and the coloring material in the ink image adheres to the liquid absorbing member, resulting in disturbance of the image. In addition, the average contact pressure was 0.08 MPa due to permanent deformation of the transfer body due to long-term use, and the amount of liquid absorbed from the ink image was insufficient.

(Example 3)
In this example, the direct-drawing ink jet recording apparatus shown in FIG. 2 was used, and the same pressing means and pressing member as in Example 2 were used as shown in FIG. The recording medium was coated paper cut into B2 size and had a thickness of about 130 μm. The initial displacement z of the pressing means by the pressing control means was set to z=0.69 mm so that the average pressure P was 0.3 MPa.

Paper may be double-fed during continuous printing. If the recording medium is double-fed, the contact pressure between the liquid absorbing member and the recording medium during liquid absorption increases, causing color transfer of the ink image to the liquid absorbing member. In this case, the thickness of one sheet of paper changes when multiple sheets are fed, which is substantially equivalent to an increase in the displacement z of 130 μm. At this time, the average contact pressure is MPa, and even if multiple feeding of the recording medium occurs, it can be used within a suitable pressure range (0.2 to 0.4 MPa).

Claims (8)

applying means for applying a liquid containing a coloring material to a recording medium to form an ink image;
a liquid absorbing member having a porous body that contacts the recording medium and absorbs at least part of the liquid from the ink image;
pressing means for pressing the first surface formed of the porous material of the liquid absorbing member against the surface of the recording medium facing the first surface;
a pressing control means for controlling pressing of the pressing means;
a transport unit that transports a recording medium;
wherein, when the recording medium conveyed by the conveying unit is nipped by the liquid absorbing member, the first surface of the porous body in contact with the ink image is brought into contact with the recording medium by the pressing means. An inkjet recording device that presses toward a surface,
The pressing means has at least two or more pressing members with different hardness,
A first pressing member and a second pressing member of the at least two or more pressing members having different hardness are arranged on the side facing the transport unit, and the second pressing member is arranged toward the transport unit. The pressing member and the first pressing member are arranged in this order,
The inkjet recording apparatus further comprises a fixing member for fixing the supporting member so as to keep the distance between the supporting member supporting the two or more pressing members of the pressing means and the conveying unit constant. 2. An ink jet recording apparatus according to claim 1, wherein displacement of said second pressing member is regulated by a fixing member and a supporting member. 3. The inkjet recording apparatus according to claim 1, wherein at least one of said second pressing members has a higher elastic modulus than said first pressing member. 4. An inkjet recording apparatus according to claim 3, wherein said second pressing member is made of rubber. 2. An inkjet recording apparatus according to claim 1, wherein the elastic modulus of said second pressing member is smaller than the elastic modulus of said first pressing member. 6. An ink jet recording apparatus according to claim 5, wherein one of said second pressing members is made of rubber. 6. An inkjet recording apparatus according to claim 5, wherein one of said second pressing members is a spring. 6. An ink jet recording apparatus according to claim 5, further comprising restraining means for displacing said second pressing member only in a predetermined direction.

Images