JP2018034438A - Image formation method and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer body which can be applied to the characteristics in nip part formation required in each step even when there is a large nip pressure difference between a liquid absorption step of absorbing an aqueous liquid component from an image using a nip part between the transfer body and a liquid adsorption member and a transfer step of transferring the image to a recording medium by using the nip part by a transfer member, and an image formation method and image formation apparatus using the same.SOLUTION: As a transfer body in an image formation method including: a liquid absorption step of absorbing an aqueous liquid component by using a nip part between a transfer body and a liquid adsorption member from an image with aqueous ink; and a transfer step of transferring the image to a recording medium by using the nip part by a transfer member, the transfer body which includes a surface layer and a plurality of compression layers having different compressive elasticity moduli, and has a crush amount in accordance with a nip pressure region that can be applied to each of the characteristics in nip part formation required in the liquid absorption step and transfer step is used.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming method and an image forming apparatus.

In image formation using water-based ink, the recording medium may curl or cockling due to excessive absorption of the water-based liquid component applied as a component of the ink. Further, when a fibrous recording medium such as paper is used, feathering may occur in which aqueous ink spreads along the fibers of the recording medium. These phenomena may cause a decrease in image quality, which is a problem to be solved.
As one of means for solving the above problems, a transfer type image forming method is known.
Patent Document 1 discloses an ink jet recording apparatus that transfers a recording image formed by ink received in a transfer body onto a recording sheet. In Patent Document 1, the transfer efficiency of a recorded image is improved by reducing the time T ₀ required for ink absorption of the recording sheet (T ₀ <T ₁ ) than the contact time T ₁ between the transfer body and the recording sheet at the time of transfer. It is supposed to improve.
On the other hand, in the transfer-type image forming method, the aqueous liquid component is removed from the image formed with the aqueous ink on the transfer body, thereby further suppressing the occurrence of curling, cockling and further feathering of the recording medium. It becomes easy.
Patent Document 2 discloses a method of removing a liquid component from an image on a transfer body using a solvent removal roller composed of a porous material as a liquid absorbing member that absorbs the liquid component contained in the image on the transfer body. Has been.
Patent Document 3 discloses a method for manufacturing a blanket for high-speed offset printing, which includes a step of stacking a large number of compressed layers having different compressive stresses. In Patent Document 3, a large number of compression layers having different compressive stresses can be stacked to achieve both durability and low compressive stress, and the force applied to the blanket surface even in the case of malfunction such as folding of printing paper or overlapping of two or more sheets. It is disclosed that the life of the surface layer can be improved by relaxing absorption.

JP-A-4-69247 JP 2009-45851 A JP 59-14997 A

As in Patent Document 2, in an image forming method including a liquid absorption process and a transfer process, the processing effect of each process can be improved by applying pressure to the image in the liquid absorption process and the transfer process. The pressure on the image can be applied as a nip pressure by a nip portion formed on the image forming surface of the transfer body.
On the other hand, the characteristics required for forming the nip portion required for the transfer body may be greatly different in each of the liquid absorption process and the transfer process.
According to the study by the present inventors, in the liquid absorption process, the liquid absorption efficiency can be increased by increasing the nip pressure. However, if the nip pressure is too high, the color material included in the image on the transfer body. A color transfer may occur in which part of the liquid adheres to the liquid absorbing member. In addition, even at a low nip pressure that can achieve both liquid absorption efficiency and prevention of color transfer, the nip portion is formed so that a uniform nip pressure is applied to the entire nip portion. Absorption is possible. On the other hand, in the transfer process, it is possible to prevent image transfer residue on the transfer body side by increasing the nip pressure. Furthermore, even at a high nip pressure, the nip portion is formed so that a uniform nip pressure is applied to the entire nip portion, so that uniform image transfer by the entire nip portion is possible.
In the image forming method including the liquid absorption process and the transfer process, even when a large nip pressure difference is set between the liquid absorption process and the transfer process, it is necessary to form the nip portion required in each process in order to further improve the image quality. It is required that the transfer body can cope with the characteristics.
However, the cited documents 1 and 2 do not disclose the above-described technical problem and means for achieving it.
Further, the blanket disclosed in the cited document 3 is for offset printing, and there is no disclosure about the above-described technical problem and means for achieving it in the transfer type image forming method using water-based ink.
Therefore, the present invention provides an aqueous ink transfer body that can cope with different characteristics required for forming the nip portion required in each process even when the nip pressure difference between the liquid absorption process and the transfer process is large, and an image using the same. An object is to provide a forming method and an image forming apparatus.

An image forming method according to the present invention includes:
An image forming step of forming a first image containing an aqueous liquid component and a coloring material by applying aqueous ink to the image forming surface of the transfer body;
The first image is pressed by the first nip pressure by the surface including the porous body in the first nip portion formed by the surface including the porous body of the liquid absorbing member and the image forming surface. A liquid absorption step in which at least a part of the aqueous liquid component is absorbed by the porous body to form a second image;
A transfer step of bringing the second image and the recording medium into contact with each other at a second nip formed by the image forming surface and the transfer member, and applying a second nip pressure to transfer the image to the recording medium;
An image forming method comprising:
The transfer body includes a compression layer having a plurality of compression elastic moduli and a surface layer including the image forming surface, and against a nip pressure when a nip portion is formed by pressurization from the image forming surface side. It has the maximum value in the second derivative of the function indicating the change in the amount of squashing,
(I) The crushing amount due to the first nip pressure is smaller than the crushing amount that takes the maximum value in the second derivative of the function,
(II) The crushing amount due to the second nip pressure is larger than the crushing amount that takes the maximum value in the second derivative of the function.
An image forming apparatus according to the present invention includes:
A transcript,
An image forming unit having an ink applying unit for applying a water-based ink to an image forming surface of the transfer body to form a first image including an aqueous liquid component and a coloring material;
A surface including a porous body that forms a first nip portion with the image forming surface, and the first image is formed by a surface including the porous body in the first nip portion by a first nip pressure. A liquid absorbing member that pressurizes and absorbs at least a part of the aqueous liquid component by the porous body to form a second image;
A second nip portion is formed by the image forming surface and the transfer member, the second image and the recording medium are brought into contact with each other at the second nip portion, and the recording medium is pressurized by a second nip pressure. A transfer unit for transferring to
An image forming apparatus comprising:
The transfer body includes a compression layer having a plurality of compression elastic moduli and a surface layer including the image forming surface, and against a nip pressure when a nip portion is formed by pressurization from the image forming surface side. It has the maximum value in the second derivative of the function indicating the change in the amount of squashing,
(I) The crushing amount due to the first nip pressure is smaller than the crushing amount that takes the maximum value in the second derivative of the function,
(II) The crushing amount due to the second nip pressure is larger than the crushing amount that takes the maximum value in the second derivative of the function.

The transfer body according to the present invention is:
A transfer material for transfer type image formation using water-based ink,
Nip pressure at the time of forming a nip portion by pressurization from the image forming surface side, having a compression layer having a plurality of compression moduli and a surface layer including an image forming surface for image formation with aqueous ink It has a maximum value in the second derivative of the function indicating the change in the amount of crushing with respect to
(I) The amount of crushing due to the pressure in the range of 0.5 to ³ kg / cm ² is smaller than the amount of crushing taking the maximum value in the second derivative of the function,
(Ii) The amount of crushing due to pressure in the range of 5 to 30.0 kg / cm ² is larger than the amount of crushing that takes the maximum value in the second derivative of the function.

  According to the present invention, even when the nip pressure difference between the liquid absorption process and the transfer process is large, the image forming method and the image forming apparatus using the transfer body that can correspond to each of the characteristics related to the nip portion formation required in each process. An apparatus can be provided.

It is a schematic diagram which shows an example of a structure of a transfer type inkjet recording device. FIG. 2 is a block diagram illustrating a control system for the entire apparatus in the ink jet recording apparatus illustrated in FIG. 1. FIG. 2 is a block diagram of a printer control unit in the transfer type inkjet recording apparatus shown in FIG. 1. It is a cross-sectional schematic diagram of the blanket used in Example 1. FIG. 3 is a relationship diagram between a crushing amount of a blanket used in Example 1 and a nip pressure. FIG. 3 is a relationship diagram between a crushing amount of a blanket used in Example 1 and a second derivative value of nip pressure.

With respect to the technical problems in the prior art described above, the present inventor diligently investigated a transfer body that can be applied even when a large nip pressure difference is set in these processes in an image forming method having a liquid absorption process and a transfer process. .
The nip pressure in the liquid absorption step can be selected from a low pressure range of 0.5 to ³ kg / cm ² in order to achieve both desired liquid absorption efficiency and prevention of color transfer to the liquid absorption member. On the other hand, the nip pressure for transferring the image in the transfer step to the recording medium can be selected from a high pressure range of 3 to 30 kg / cm ² . Thus, when each pressure is selected from these pressure ranges, these ratios may be three times or more.
If there is such a difference in the nip pressure between the liquid absorption process and the transfer process, for example, if the compression layer suitable for the low nip pressure in the liquid absorption process is used to achieve the nip pressure in the transfer process, the compression layer is completely crushed. End up. In the state where the compressed layer is completely crushed, the effect of the compressed layer cannot be obtained in the transfer process, and a uniform nip pressure cannot be obtained in the nip portion. There are cases where image distortion or deformation occurs during image transfer.
On the other hand, if the compression layer suitable for the high nip pressure used in the transfer process is used to achieve the nip pressure in the liquid absorption process, it is necessary to adjust the nip pressure in a range where the crushing amount is 0.1 μm or less. Since it is difficult to suppress the variation in the thickness of the surface of the transfer member within the range of several tens of μm, the same amount of variation occurs in the amount of crushing in the surface of the transfer member when the pressure is applied. It is very difficult to control the amount of crushing in units of 01 mm. If the squeezing amount varies widely within the surface, the nip pressure varies depending on the squeezing amount, so that a uniform nip pressure cannot be obtained at the nip portion. When trying to cope with an image forming method having both a liquid absorption process and a transfer process using a transfer body having a compression layer having a single compression modulus, if the difference in nip pressure between the two processes is large, There are cases where the nip pressure of both processes cannot be handled.
As a blanket for offset printing, Patent Document 3 discloses a blanket manufacturing method in which multiple compression layers having different compression stresses are stacked in order to efficiently absorb and relieve normal printing pressure and excessive printing pressure applied suddenly. Has been proposed. However, the compressive stress of each compression layer having a multilayer structure of the blanket described in Patent Document 3 is selected in order to achieve both durability for offset printing and low compressive stress. Therefore, the cited document 3 does not describe or suggest any configuration of the compression layer that can correspond to the characteristics required in each of these steps in the image forming method using the aqueous ink having the liquid absorption step and the transfer step. .

The inventors of the present invention provide a transfer body having both a squeezing amount change region in a nip pressure range suitable for a liquid absorption process and a squeezing amount change region in a nip pressure range suitable for a transfer process. We obtained new knowledge that it is applicable even when the nip pressure difference is large. The present inventors have further completed the present invention by obtaining new knowledge that the characteristics relating to the nip portion can be achieved by using a compression layer having a plurality of compression elastic moduli.
The image forming method according to the present invention includes an image forming process, a liquid absorption process, and a transfer process.
In the image forming process, ink is applied to the image forming surface of the transfer body. A water-based ink containing water is used as the ink, and a first image containing a water-based liquid component and a color material is formed on the image forming surface of the transfer body.
In the liquid absorption process, the surface including the porous body of the liquid absorbing member contacts the first image formed on the image forming surface of the transfer body under pressure, so that at least the aqueous liquid component included in the first image is present. A part of the liquid absorbing member absorbs part of the liquid, and a second image in which the liquid content is removed or reduced is formed.
In the transfer process, the recording medium comes into contact with the second image on the image forming surface of the transfer body under pressure, and the image adhering to the recording medium is transferred to the recording medium side by being separated from the image forming surface of the transfer body. The
In the liquid absorption step, the contact of the liquid absorbing member with the first image under pressure forms a nip portion by the surface including the porous body of the absorbing member and the image forming surface of the transfer member. This is done by applying a nip pressure to the first image.
In the transfer process, the second image is contacted with the recording medium under pressure by forming a nip portion with the image forming surface of the transfer member and the transfer member, and in contact with the second image and the recording medium in the nip portion. This is done by applying a nip pressure. At the nip portion, the image sandwiched between the image forming surface of the transfer body and the recording medium pressed by the transfer member is attached to the recording medium by the nip pressure, and attached to the recording medium by pulling the recording medium away from the transfer body. The image is transferred to the recording medium side.
Hereinafter, the nip portion and nip pressure in the liquid absorption process are referred to as “first nip portion” and “first nip pressure”, and the nip portion and nip pressure in the transfer step are referred to as “second nip portion” and “second nip portion”. The nip pressure ”.

The transfer body has a compression layer having a plurality of compression elastic moduli and a surface layer including image formation.
Since the transfer body has a plurality of compression layers having compression elastic moduli, a function indicating a change in the squeezing amount with respect to the nip pressure when the nip portion is formed by pressurization from the image forming surface side is a second derivative. Indicates the maximum value.
The crushing amount indicates the penetration depth of the pressure member from the image forming surface when no pressure is applied when the nip portion is formed by pressing the image forming surface with the pressure member.
As characteristics relating to the formation of the nip portion by the transfer member, the first squashing amount at the first nip pressure and the second squashing amount at the second nip pressure are set as follows.
(I) The crushing amount by the first nip pressure is smaller than the crushing amount that takes the maximum value in the second derivative of the above-described function.
(II) The crushing amount by the second nip pressure is larger than the crushing amount that takes the maximum value in the second derivative of the function.
By selectively using a crushing amount area that is lower than the maximum crushing amount and a high crushing area in the liquid absorption process and the transfer process, both characteristics required for nip formation required in each process are obtained. It is possible to provide a transfer body that can be used. In other words, the area of the squashing amount lower than the above-mentioned squashing amount that takes the maximum value is used as a region that can achieve both absorption of the liquid component from the first image and prevention of color transfer, and the squashing amount that takes the maximum value mentioned above. A high squashing area is used in the transfer process.

FIG. 5 shows an example of a function indicating the change in the amount of crushing with respect to the nip pressure when the compression layer has two compression moduli E ₁ and E ₂ (E ₁ <E ₂ ). Further, FIG. 6 shows the change of the second derivative value of this function. These figures show graphs in which the vertical axis represents the nip pressure and the horizontal axis represents the crushing amount. The maximum value α in the second derivative of the crushing amount with respect to the nip pressure in this example is at a point where the crushing amount is 0.4 mm.
The compression layer of the transfer member having the characteristics shown in FIG. 5 includes a region having a relatively small compression modulus, that is, a relatively soft region, and a region having a relatively large compression modulus, that is, a relatively hard region. Have When a nip pressure is applied to the compressed layer, first, a crushing amount due to deformation of a relatively soft region is obtained. When the nip pressure applied to the relatively soft area becomes larger than a certain value, this area is completely crushed and the further deformation is almost impossible. The point at which this relatively soft area is not deformed is the maximum value α of the second derivative of the squashing amount. A relatively hard region is deformed to cope with a nip pressure at which a crushing amount larger than the maximum value α is obtained. In a relatively soft region, the change in the squeezing amount with respect to the nip pressure is small, that is, the inclination in the graph of FIG. 5 is small, and the control of the squeezing amount necessary for nip formation at a low pressure becomes easy. On the other hand, in the relatively hard region, the change in the crushing amount with respect to the nip pressure is large, that is, the inclination in the graph of FIG. 5 is large, and a high nip pressure can be obtained even with a small crushing amount. Therefore, in the present invention, a compression layer is formed so as to satisfy the above-mentioned specific (I) and (II) related to the maximum value α, and the compression elastic modulus corresponding to the low nip pressure divided by the maximum value α is obtained. The area of compression modulus corresponding to the area and high nip pressure is properly used. Even when three or more different compression elastic moduli are used for the compression layer, the present invention aims to configure the regions (or layers) having these compression elastic moduli to have the characteristics shown in FIG. A compressed layer can be obtained.
Therefore, in the case of the transfer body having the characteristics shown in FIG. 5, the nip pressure in the liquid absorption process is selected from the area of the crushed amount smaller than 0.4 mm, and the transfer process from the area of the crushed amount larger than 0.4 mm. Nip pressure is selected. The physical characteristics related to the change in the crushing amount with respect to the nip pressure shown in FIG. 5 can be obtained by providing a plurality of compression layers having different compression elastic moduli below the surface layer. That is, it is necessary for each of the processes of the nip pressure and the squeezing amount satisfying the characteristics of both the absorption of the liquid component by the liquid absorbing member and the prevention of color transfer, and the nip pressure and the squeezing amount satisfying the characteristics for image transfer. The characteristics relating to the formation of the nip portion can be realized by one transfer body. Furthermore, even when the second nip pressure is three times or more the first nip pressure, it is possible to provide good processing conditions in each of the liquid absorption process and the transfer process.
Each layer constituting the transfer body will be further described in the section <Transfer body> described later.

In the image forming step, in addition to the ink, a reaction liquid containing an ink thickening component can be used. By forming the first image from the ink and the reaction liquid, it is more effective to bleed the ink applied adjacently and the beading that the ink that landed first is attracted to the ink that landed later. Can be suppressed.
The ink and the reaction liquid are applied to the image forming surface of the transfer body so that at least a part thereof overlaps. The order of applying the ink and the reaction liquid to the transfer body is not particularly limited. From the viewpoint of promoting the fixing of the coloring material of the first image and more effectively suppressing the occurrence of bleeding and beading, it is preferable to apply the ink after applying the reaction liquid to the transfer body.

An image forming apparatus that can be used in the above-described image forming method includes a transfer body, an image forming unit, a liquid absorbing member, and a transfer unit.
The transfer body has the above-described configuration.
The image forming unit includes an ink applying unit that applies ink to an image forming surface of the transfer body and forms a first image including an aqueous liquid component and a color material applied by the ink.
The liquid absorbing member has a surface including a porous body that forms an image forming surface of the transfer body and a first nip portion. In the first nip portion, the first image is pressed by the first nip pressure by the surface including the porous body, and at least a part of the aqueous liquid component contained in the first image is absorbed by the porous body. A second image is formed.
The transfer unit forms a second nip portion by the image forming surface of the transfer body and the recording medium, and presses the second image with the recording medium by the second nip pressure in the second nip portion to form the recording medium. Transfer the image.
The image forming unit can have a reaction liquid applying unit that applies the reaction liquid containing the ink viscosity increasing component described above to the transfer body.

Hereinafter, embodiments of the present invention will be described. In the following, “reaction liquid application device” is used as the reaction liquid application unit, “ink application device” is used as the ink application unit, and “liquid absorption device” is used as the liquid absorption unit having the liquid absorption member.
<Reaction solution applying apparatus>
In the case of forming the first image with the ink and the reaction liquid, the reaction liquid applying apparatus may be any apparatus that can apply the reaction liquid onto the transfer body, and various conventionally known apparatuses can be appropriately used. .
Specific examples include a gravure offset roller, an inkjet head, a die coating device (die coater), a blade coating device (blade coater), and the like. The application of the reaction liquid by the reaction liquid application device may be performed before application of the ink or after application of the ink as long as the reaction liquid can be mixed (reacted) with the ink on the transfer body. Preferably, the reaction liquid is applied before applying the ink. By applying the reaction liquid before applying ink, bleeding that mixes ink applied adjacent to each other at the time of image recording and beading that ink that has landed first is attracted to ink that has landed later are more effective. Can also be suppressed.

<Reaction solution>
The reaction liquid contains an ink thickening component. The increase in viscosity of the ink includes at least one of the following (a) and (b).
(A) A color material, resin, or the like, which is a part of the composition constituting the ink, chemically reacts or physically adsorbs by coming into contact with the ink viscosity increasing component. When an increase in viscosity is observed.
(B) A case where a viscosity rises locally due to agglomeration of a part of components constituting the ink such as a color material.
This ink viscosity increasing component reduces the fluidity of a part of the ink on the recording medium, and has the effect of suppressing bleeding and beading during the first image formation. As such an ink viscosity increasing component, known ones such as polyvalent metal ions, organic acids, cationic polymers, and porous fine particles can be used. Of these, polyvalent metal ions and organic acids are particularly suitable. It is also preferable to include a plurality of types of ink thickening components. The content of the ink viscosity increasing component in the reaction liquid is preferably 5% by mass or more based on the total mass of the reaction liquid.
Examples of the 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+. Of the 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, lactic acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, oxysuccinic acid, dioxysuccinic acid and the like.
The reaction liquid can contain an appropriate amount of water or a low-volatile organic solvent as an aqueous liquid medium. The water used in this case is preferably water deionized by ion exchange or the like. It does not specifically limit as an organic solvent which can be used for a reaction liquid, A well-known organic solvent can be used.
The reaction liquid can be used by appropriately adjusting the surface tension and viscosity by adding a surfactant or a viscosity modifier. The material used is not particularly limited as long as it can coexist with the ink thickening component. Specifically used surfactants include acetylene glycol ethylene oxide adduct (“acetylenol E100” (trade name) manufactured by Kawaken Fine Chemical Co., Ltd.), perfluoroalkyl ethylene oxide adduct (“Megafac F444” (trade name) DIC). Fluorine-based surfactants such as “Capstone FS-3100” (trade name) The Chemours Company LLC, Zonyl FS3100 (trade name) manufactured by DuPont, etc., and polyether-modified polydimethylsiloxane adducts (“BYK 349” (trade name) And silicone surfactants such as BYK).

<Ink application device>
The ink applying device for applying ink to the transfer body is not particularly limited as long as it can form a first image by applying aqueous ink to the image forming surface of the transfer body. Application of water-based ink to the transfer body can be performed by an ink-jet method, and an ink-jet device having an ink-jet head by an ink-jet method can be used as the ink application device.
As an inkjet head, there exist the following forms, for example.
A form in which ink is ejected by causing film boiling in the ink by an electro-thermal converter to form bubbles.
A mode in which ink is ejected by an electromechanical converter.
-A mode of discharging ink using static electricity.
As the ink jet head to be mounted on the ink applicator, a known ink jet head can be used. Among these, those using an electro-thermal converter are preferably used from the viewpoint of high-speed and high-density printing. Drawing receives an image signal and applies a necessary ink amount to each position.
The ink application amount can be expressed by the image density (duty) and the ink thickness. The average value obtained by multiplying the mass of each ink dot by the number of application and dividing by the printing area is defined as the ink application amount (g / m ² ). . Note that the maximum ink application amount in the image region indicates the ink application amount applied in an area of at least 5 mm ² or more in the region used as information of the transfer body from the viewpoint of removing the liquid component in the ink. .
The ink jet device may have a plurality of ink jet heads in order to apply ink of each color onto the transfer body. For example, when each color image is formed using yellow ink, magenta ink, cyan ink, and black ink, the ink jet device has four ink jet heads that respectively eject the four types of ink onto the transfer body.
In addition, the ink application device may include an inkjet head that ejects ink (clear ink) that does not contain a color material.

<Ink>
Each component of the ink will be described.
(Color material)
As the color material contained in the ink, a pigment, a dye, or a mixture thereof can be used. The kind of pigment that can be used as the color material is not particularly limited. Specific examples of the pigment include inorganic pigments such as carbon black; organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole, and dioxazine. These pigments can be used alone or in combination of two or more as required.
The kind of dye that can be used as the color material is not particularly limited. Specific examples of the dye include direct dyes, acid dyes, basic dyes, disperse dyes, food dyes, and the like, and dyes having an anionic group can be used. Specific examples of the dye skeleton include an azo skeleton, a triphenylmethane skeleton, a phthalocyanine skeleton, an azaphthalocyanine skeleton, a xanthene skeleton, and an anthrapyridone skeleton.
The content of a coloring material such as a pigment 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 with respect to the total mass of the ink. It is more preferable.

(Dispersant)
As the dispersant for dispersing the pigment in the ink, known dispersants used for water-based inks, especially for inkjet inks can be used. As the dispersant, it is preferable to use a water-soluble dispersant having both a hydrophilic part and a water-repellent part in the structure. In particular, a pigment dispersant made of a resin obtained by copolymerizing at least a hydrophilic monomer and a water repellent monomer is preferably used. There is no restriction | limiting in particular about each monomer used here, A well-known thing is used suitably. Specifically, examples of the water repellent monomer include styrene and other styrene derivatives, alkyl (meth) acrylate, and benzyl (meth) acrylate. Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, maleic acid and the like.
The acid value of the dispersant is preferably 50 mgKOH / g or more and 550 mgKOH / g or less. Moreover, it is preferable that the weight average molecular weights of this dispersing agent are 1000 or more and 50000 or less. The mass ratio of pigment to dispersant (pigment: dispersant) is preferably in the range of 1: 0.1 to 1: 3.
In addition, it is also preferable in the present invention to use a so-called self-dispersing pigment that can be dispersed by surface modification of the pigment itself without using a dispersant.

(Resin fine particles)
The ink can be used by containing various fine particles having no coloring material. Among these, resin fine particles are preferable because they may be effective in improving image quality and fixability.
The material of the resin fine particles is not particularly limited, and a known resin can be appropriately used. Specifically, a homopolymer such as polyolefin, polystyrene, polyurethane, polyester, polyether, polyurea, polyamide, polyvinyl alcohol, poly (meth) acrylic acid and its salt, poly (meth) acrylate alkyl, polydiene, or the like And a copolymer obtained by polymerizing a plurality of monomers for producing these homopolymers. The weight average molecular weight (Mw) of the resin is preferably in the range of 1,000 to 2,000,000. Further, the amount of the resin fine 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 with respect to the total mass of the ink.
The resin fine particles are preferably used as a resin fine particle dispersion dispersed in a liquid. A dispersion method is not particularly limited, but a so-called self-dispersing resin fine particle dispersion in which a monomer having a dissociable group is homopolymerized or a resin obtained by copolymerizing a plurality of types is preferably used. Here, examples of the dissociable group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and examples of the monomer having this dissociable group include acrylic acid and methacrylic acid. 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 invention. As the emulsifier, a known surfactant is preferable regardless of the low molecular weight or high molecular weight. The surfactant is preferably a nonionic surfactant or a surfactant having the same charge as the resin fine particles.
The resin fine particle dispersion preferably has a dispersed particle diameter of 10 nm to 1000 nm, and more preferably has a dispersed particle diameter of 100 nm to 500 nm.
In preparing the resin fine particle dispersion, it is also preferable to add various additives for stabilization. Examples of the additive include n-hexadecane, dodecyl methacrylate, stearyl methacrylate, chlorobenzene, dodecyl mercaptan, blue dye (bluing agent), and polymethyl methacrylate.

(Surfactant)
The ink may contain a surfactant. Specific examples of the surfactant include acetylene glycol ethylene oxide adducts (acetylene E100, manufactured by Kawaken Fine Chemical Co., Ltd.). The amount of the 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 solvents)
Water-based ink is used as the ink. The water-based ink includes a color material and an aqueous liquid medium. The aqueous liquid medium is a liquid medium containing at least water. As an ink containing an aqueous liquid medium, that is, an aqueous ink, an aqueous pigment ink containing at least a pigment as a coloring material can be used.
The aqueous liquid medium can further contain a water-soluble organic solvent as required. The water is preferably water deionized by ion exchange or the like. Further, the water content 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.
Moreover, the kind of water-soluble organic solvent to be used is not particularly limited, and any known organic solvent can be used. Specifically, glycerin, diethylene glycol, polyethylene glycol, polypropylene glycol, ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, thiodiglycol, hexylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, 2-pyrrolidone, ethanol , Methanol, and the like. Of course, it is also possible to use a mixture of two or more selected from these.
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)
In addition to the above components, the ink that can be used in the present invention is a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, an anti-reduction agent, a water-soluble resin, and a neutralizer thereof, as necessary In addition, various additives such as a viscosity modifier may be contained.

<Liquid absorbing member>
By contacting the first image and the surface including the porous body of the liquid absorbing member, at least a part of the aqueous liquid component is absorbed by the porous body from the first image. This reduces the amount of liquid in the first image. The surface for contacting the first image of the surface including the porous body of the liquid absorbing member functions as a liquid absorbing surface.
(Porous body)
The porous body preferably has a small pore diameter in order to suppress coloring material adhesion from the first image, that is, ink transfer, and at least the pore diameter of the porous body on the side in contact with the image is 10 μm or less. preferable. On the other hand, in order to improve the absorbability of the liquid component in the porous body, it is preferable that the average pore diameter of the porous body at least on the contact surface side with the image is 0.05 μm or more.
In the present invention, the pore diameter means an average diameter, and can be measured by a known means such as a mercury intrusion method, a nitrogen adsorption method, or an SEM image observation.
Further, it is preferable to reduce the thickness of the porous body in order to obtain a uniform high air permeability. The air permeability can be indicated by a Gurley value defined by JIS P8117, and the Gurley value is preferably 10 seconds or less. The shape of the liquid absorbing member having a porous body is not particularly limited, and examples thereof include a roller shape, a belt shape, an endless belt shape, and a sheet shape.
When the liquid absorbing member such as a roller has rigidity capable of forming the first nip portion, the first nip portion can be formed by the liquid absorbing member and the transfer body. If the belt-shaped liquid absorbing member does not have rigidity capable of forming the first nip portion, the liquid absorbing member is pressurized with a pressure member of an appropriate shape and the first nip is formed between the belt and the transfer member. The part can be formed.
When the porous body is thinned, the capacity necessary for absorbing the aqueous liquid component contained in the first image may not be sufficiently secured, so that the porous body can have a multilayer structure. In the liquid absorbing member, the layer in contact with the image on the transfer body may be a porous body, and the layer not in contact with the image on the transfer body may not be a porous body.
Moreover, there is no restriction | limiting in particular about the manufacturing method of a porous body, All the manufacturing methods widely used conventionally are applicable. As an example, Japanese Patent No. 1114482 discloses a method for producing a porous body obtained by biaxially stretching a resin containing polytetrafluoroethylene.

In the present invention, the material for forming the porous body is not particularly limited, and both a hydrophilic material having a contact angle with respect to water of less than 90 ° and a water repellent material having a contact angle of 90 ° or more are used. be able to.
In the case of a hydrophilic material, the contact angle with water is more preferably 40 ° or less. In the case of a hydrophilic material, there is an effect of sucking up liquid by capillary force.
Examples of the hydrophilic material include polyolefin (polyethylene (PE) and the like), polyurethane, nylon, polyamide, polyester (polyethylene terephthalate (PET) and the like), polysulfone (PSF) and the like.
The porous body preferably has water repellency from the viewpoint of obtaining the releasability of the color material contained in the first image. The water repellent porous body preferably has a contact angle of 90 ° or more with pure water. As a result of intensive studies by the present inventors, it has been found that by using a porous body having a contact angle with pure water of 90 ° or more, ink color material adhesion to the porous body can be suppressed. In this specification, the contact angle is an angle formed by dropping the measurement liquid onto the object and forming the surface of the object at the portion where the liquid droplet is in contact with the object and the tangent of the liquid droplet. Although there are several types of measurement techniques, the present inventor measured water repellency according to the technique described in “6. Static Method” of JIS R3257.
The material of the water repellent porous material is not particularly limited as long as the contact angle with the ink is 90 ° or more, but is preferably made of a water repellent resin material. Furthermore, the water repellent resin material is preferably a fluororesin. Specific examples of fluororesins include polytetrafluoroethylene (hereinafter PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxy fluororesin (PFA), Examples thereof include tetrafluoroethylene / hexafluoropropylene copolymer (FEP), ethylene / tetrafluoroethylene copolymer (ETFE), and ethylene / chlorotrifluoroethylene copolymer (ECTFE). These resins may be used singly or in combination of two or more as required, and may have a structure in which a plurality of films are laminated. Of these, polytetrafluoroethylene is preferred.

<Multilayer configuration>
Next, an embodiment in which the porous body has a multilayer structure will be described. Here, the first layer on the side in contact with the first image and the layer laminated on the surface of the first layer opposite to the contact surface with the first image will be described as the second layer. Further, the multilayer structure is also expressed in the order of stacking from the first layer.
[First layer]
The first layer can be formed from the porous body described above in the section “(Porous body)”.
From the viewpoint of suppressing coloring material adhesion and improving the cleaning property, it is preferable to use a porous body made of the above-described water-repellent material for the first layer. The resin as the water repellent material may be used alone or in combination of two or more as required, and may have a structure in which a plurality of films are laminated in the first layer.
When a porous body made of a water repellent material is used, it is preferable to perform a pretreatment described later.
The film thickness of the first layer is preferably 50 μm or less, and more preferably 30 μm or less. The film thickness can be obtained by measuring the film thickness at any 10 points with a straight-forward 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 film porous membrane. For example, a porous film for the first layer can be obtained by obtaining a sheet-like material from a resin material by a method such as extrusion molding and then stretching the resin material to a predetermined thickness. Further, a porous film for the first layer can be obtained by adding a plasticizer such as paraffin to the material at the time of extrusion molding and removing the plasticizer by heating at the time of stretching. The pore diameter can be adjusted by appropriately adjusting the amount of plasticizer to be added, the draw ratio, and the like.

[Second layer]
In the present invention, 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 aqueous liquid component absorbed from the image is the same for the first layer so that the liquid absorbed to the first layer side does not flow backward. It is preferable that the material is lower than that. Specifically, a single material such as polyolefin (polyethylene (PE), polypropylene (PP), etc.), polyurethane, nylon, polyamide, polyester (polyethylene terephthalate (PET), etc.), polysulfone (PSF), or these It is preferably selected from composite materials and the like. The second layer is preferably a layer having a larger pore size than the first layer.
[Third layer]
In the present invention, the porous body having a multilayer structure may be composed of three or more layers, and is not limited. The third and subsequent layers (third layer) and subsequent layers are preferably nonwoven fabrics from the viewpoint of rigidity. The same material as the second layer is used.
[Other materials]
The liquid absorbing member may include a reinforcing member that reinforces the side surface of the liquid absorbing member in addition to the porous body having the above-described laminated structure. Moreover, you may have a joining member at the time of connecting the longitudinal direction edge part of a elongate sheet-shaped porous body to make 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 a period not in contact with the image.

[Method for producing porous body]
The method for forming the porous body by laminating the first layer and the second layer is not particularly limited. They may be simply overlapped or may be bonded together using a method such as adhesive lamination or heat lamination. From the viewpoint of air permeability, thermal lamination is preferred in the present invention. Further, for example, a part of the first layer or the second layer may be melted and laminated by heating. Alternatively, a fusing material such as hot melt powder may be interposed between the first layer and the second layer and bonded together by heating. When the third layer or more are stacked, they may be stacked at once or sequentially, and the stacking order is appropriately selected.
In the heating step, a laminating method is preferred in which the porous body is heated while sandwiching and pressing the porous body with a heated roller.

Next, an embodiment of the image forming apparatus of the present invention will be described.
FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of a transfer type inkjet recording apparatus 100 according to the present embodiment.
The illustrated transfer type inkjet recording apparatus 100 includes a transfer unit having an image forming transfer body 101 supported by a support member 102, a reaction liquid applying apparatus 103, an ink applying apparatus 104, a liquid absorbing apparatus 105, and a transfer member 106. . Application of the reaction liquid onto the transfer body 101 is performed by the reaction liquid application apparatus 103, and ink is applied from the ink application apparatus 104 onto the transfer body 101 to which the reaction liquid has been applied, and a first image is formed on the transfer body. It is formed. The first image on the transfer body becomes a second image used for forming a transfer image on the recording medium by absorption of at least a part of the aqueous liquid component by the liquid absorbing device 105. The second image on the transfer body is transferred by a transfer unit having a transfer member 106 on a recording medium 108 such as paper. Thus, the first image and the second image obtained by absorbing and removing at least part of the aqueous liquid component from the first image are temporarily held on the image forming surface of the transfer body. The image transferred to the recording medium becomes a final image corresponding to the intended use.
Further, the transfer type inkjet recording apparatus 100 may include a transfer body cleaning member 109 that cleans the surface of the transfer body 101 after the transfer as necessary.
The support member 102 rotates around the rotation shaft 102a in the direction of the arrow in FIG. The transfer body 101 is moved by the rotation of the support member 102. In synchronization with the movement of the transfer body 101, each device provided around the transfer body operates.
As the transfer body 101 moves, the reaction liquid application device 103 and the ink application apparatus 104 sequentially apply the reaction liquid on the transfer body 101 and form a first image on the transfer body 101. . The first image formed on the transfer body 101 is moved to a position in contact with the liquid absorbing member 105 a included in the liquid absorbing device 105 by the movement of the transfer body 101.
The transfer body 101 and the liquid absorbing device 105 move in synchronization with each other, and the first image passes through a state in which the first image is in contact with the liquid absorbing member 105a. During this time, the liquid absorbing member 105a removes the aqueous liquid component from the first image.
In the first image, most of the aqueous liquid component is removed by going through the state in contact with the liquid absorbing member 105a. At this time, the first image and the liquid absorbing member 105a are in contact with each other with a predetermined pressure (first nip pressure) in the first nip formed by the surface layer of the transfer body 101 and the pressure member 105b. Therefore, the liquid absorbing member 105a can function effectively.

If the removal of the aqueous liquid component is described 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 content ratio with respect to the solid aqueous liquid component such as the coloring material or resin contained in the ink increases as the aqueous liquid component contained in the ink decreases.
Then, the image from which the aqueous liquid component has been removed is moved to the transfer unit in contact with the recording medium 108 by the movement of the transfer body 101, and is pressed against the recording medium 108 conveyed to the transfer unit by the recording medium conveying device 107. Thus, an image is formed on the recording medium. The image transferred onto the recording medium 108 is a reverse image of the second image.
In this embodiment, since the reaction liquid is applied to the transfer body 101 and then ink is applied to form an image, the reaction liquid remains in the non-image area without reacting with the ink. In the apparatus according to the present embodiment, the liquid absorbing member 105a is in contact (pressure contact) with not only the image but also the unreacted reaction liquid, and the reaction liquid itself or the liquid component contained in the reaction liquid is also removed.
Therefore, in the above, it is expressed and explained that the aqueous liquid component is removed from the image, but this is not a limited meaning of removing the aqueous liquid component from only the image. When the reaction liquid is used in combination, at least on the transfer body. It is used in the sense that the liquid component only needs to be removed from the image.
The liquid component is not particularly limited as long as it does not have a certain shape, has fluidity, and has a substantially constant volume.
For example, the water or organic solvent contained in the ink, the reaction liquid itself, or the water or organic solvent contained in the reaction liquid can be cited as the liquid component. When the reaction liquid is used in combination, at least these liquid components are used. A part is removed from the transfer member by the liquid absorbing member.

Each configuration of the transfer type inkjet recording apparatus of this embodiment will be described below.
<Transfer>
The transfer body 101 has a compression layer and a surface layer provided on the compression layer and including an image forming surface.
As a member constituting the surface layer, various materials such as a resin and a ceramic can be used as appropriate, but a material having a high compression elastic modulus is preferable in terms of durability. Specific examples include condensates obtained by condensing acrylic resins, acrylic silicone resins, fluorine-containing resins, and hydrolyzable organosilicon compounds. In order to improve the wettability and transferability of the reaction solution, surface treatment may be performed. Examples of the 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. Moreover, arbitrary surface shapes can also be provided in the surface layer.
The thickness of the surface layer is set so as not to impair the strength and surface characteristics necessary for forming the image forming surface and further the function of the compression layer. The thickness of the surface layer is preferably 0.05 to 0.5 mm. From such a viewpoint, it is preferable that the thickness is smaller than the thickness of the compression layer. Moreover, it is preferable that the compression elastic modulus of a surface layer is set higher than the lowest compression elastic modulus which a compression layer has.
The compression layer has a function of absorbing pressure fluctuations. By providing the compression layer, the compression layer absorbs deformation, disperses the fluctuation with respect to the local pressure fluctuation, and can maintain good transferability even during high-speed printing. Examples of the member forming the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, and silicone rubber. In molding the rubber material, a predetermined amount of a vulcanizing agent, a vulcanization accelerator, and the like are blended, and a filler such as a foaming agent, hollow fine particles, or salt is blended as necessary to make it porous. Thereby, since the bubble part is compressed with a volume change with respect to various pressure fluctuations, deformation in the direction other than the compression direction is small, and more stable transferability and durability can be obtained. The porous rubber material includes a continuous pore structure in which the pores are continuous with each other and an independent pore structure in which the pores are independent from each other. In the present invention, any structure may be used, and these structures may be used in combination.

The compression layer has a plurality of different compression moduli. The number of different compression moduli and the value of each compression moduli are selected so as to satisfy the characteristics (I) and (II) related to the nip formation in the intermediate transfer member mentioned above.
When the compression layer has two different compression elastic moduli, the first compression elastic modulus E ₁ and the second compression elastic modulus E ₂ (E ₁ <E ₂ ), the nip pressure collapse in the liquid absorption process. the amount mainly set based on the E ₁ a, it is preferable to mainly set based on the E ₂ the nip圧及crushing amount in the transfer process. These E ₁ and E ₂ correspond to two areas divided by the maximum value α of the squashing amount in the second derivative, and can be set according to the nip pressure used in the liquid absorption process and the transfer process. it can. For example, a first nip pressure in the liquid absorption step from the scope of 0.5~3kg / cm ^2, the second nip pressure in the transfer step, when selected, respectively from the range of 3 to 30 kg / cm ² is It is preferable to select E ₁ from 3 MPa or less, preferably from 0.1 to 3 MPa, and E ₂ from 1.0 to 30.0 MPa. The difference between E ₁ and _{E 2} is preferably selected such that 2.0～20.0MPa. Difference in compression modulus and the second compression modulus _{E 2} of the surface layer is preferably 5.0～100MPa.
The compressed layer is preferably formed of a material having voids such as the porous body described above in order to improve the responsiveness of absorbing pressure. If the porosity is too low, the structure of the layer cannot be maintained, and if it is too high, the pressure may not be sufficiently absorbed. Therefore, it is preferably used in the range of 10 to 90%.
The thickness of the entire compression layer is preferably selected from the range of 0.2 to 2.0 mm in order to balance the absorption of pressure and the amount of deformation during pressure application. In the case of a configuration having two compression layers, the thickness of the first compression layer is preferably 0.1 to 1.0 mm, and the thickness of the second compression layer is preferably 0.1 to 1.5 mm.
In order to achieve a uniform nip pressure in the liquid absorption process in the transfer body, in order to sufficiently absorb the pressure even at a low pressure, the compression elastic modulus corresponding to the low nip pressure is a compression corresponding to the high nip pressure. It is preferable to be located closer to the surface layer side of the transfer body than the elastic modulus.
The compression layer can have a single layer configuration or a multi-layer configuration of two or more layers. When a compression layer consists of a single layer, the area | region which has several compression elastic modulus which differs in the layer thickness direction is formed. When a plurality of compression layers are used, each layer is formed such that at least one combination of layers having different compression moduli exists in the plurality of layers.
When the compression layer has a plurality of layers, it is preferably two layers or three layers. In one layer, the effect of the present invention cannot be obtained, and in the case of four layers or more, the configuration becomes complicated and the difficulty in production increases. When three compression layers are used, three compression elastic moduli of E ₁ , E _{2 and} E ₃ are obtained. For example, when two pressure members are used in the liquid absorption process and the nip has two nips, three nip portions are provided together with the transfer process. Even in the case of such a configuration using three nip portions, it can be set according to the nip pressure used in the two nip portions in the liquid absorption process and the nip portion in the transfer process. In such a configuration, the first nip pressure in the liquid absorption step is in the range of 0.5 to 3 kg / cm ² , the second nip pressure is in the range of 1 to 5 kg / cm ² , and the nip pressure in the transfer step is changed. In the case of selecting from the range of 3 to 30 kg / cm ² , E ₁ is in the range of 0.1 to 3 MPa, E ₂ is in the range of 1.0 to 5.0 MPa, and E ₃ is in the range of 3.0 to It is preferable to select from the range of 30.0 MPa. In this case, E ₁ and E ₂ correspond to the lower nip pressure region divided by the maximum value α of the squashing amount in the second derivative, and E ₃ corresponds to the higher nip pressure region.
Further, the transfer body preferably has an elastic layer between the surface layer and the compression layer. As a member for forming the elastic layer, various materials such as resin and ceramic can be used as appropriate. Various elastomer materials and rubber materials are preferably used in terms of processing characteristics and the like. Specifically, for example, fluorosilicone rubber, phenyl silicone rubber, fluoro rubber, chloroprene rubber, urethane rubber, nitrile rubber, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, ethylene / propylene / butadiene copolymer, A nitrile butadiene rubber etc. are mentioned.
In particular, silicone rubber, fluorosilicone rubber, and phenyl silicone rubber are preferable in terms of dimensional stability and durability because they have a small compression set. In addition, these rubber materials have a small change in elastic modulus with temperature, and are preferable in terms of transferability.
Various adhesives and double-sided tapes may be used between each layer (surface layer, elastic layer, compression layer) constituting the transfer body in order to fix and hold them.
The thickness and elastic modulus of the elastic layer, or the adhesive layer and the double-sided tape are selected within a range in which the desired function can be obtained by providing the elastic layer without impairing the characteristics required for the transfer body according to the present invention. be able to.
In addition, a reinforcing layer having a high compression elastic modulus may be provided on the surface opposite to the surface layer, in the present embodiment, on the surface on the support 102 side, in order to suppress lateral elongation when the device is mounted and to maintain stiffness. . A woven fabric may be used as the reinforcing layer. The transfer body can be produced by arbitrarily combining the layers made of the above materials.

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 include a sheet shape, a roller shape in which the support member and the transfer body are integrated, a belt shape, and an endless web shape.
When the transfer body such as a roller has rigidity capable of forming the nip portion, the nip portion can be formed by the transfer body itself. When the belt-like transfer body does not have the rigidity capable of forming the nip portion, the transfer body can be pressed by an appropriate-shaped transfer body pressing member to form the nip portion.
FIG. 4 shows a schematic partial cross-sectional view of an example of a four-layered transfer body. The transfer body shown in FIG. 4 has a structure in which a second compression layer 42, a first compression layer 41, and a surface layer 40 are laminated in this order on a support layer 43 made of a support member. Each layer is bonded by an adhesive.
The first compression layer 41 and the second compression layer 42 have the first compression elastic modulus E ₁ and the second compression elastic modulus E _{2 described above} , respectively.
The compression modulus of the surface layer is preferably smaller than the second compression modulus.

<Supporting member>
The transfer body 101 is supported on a support member 102. Various adhesives and double-sided tapes may be used as a method for supporting the transfer body. Alternatively, the transfer member may be supported on the support member 102 using the installation member by attaching an installation member made of metal, ceramic, resin, or the like to the transfer member.
The support member 102 is required to have a certain degree of structural strength from the viewpoint of conveyance accuracy and durability. For the material of the support member, metal, ceramic, resin or the like is preferably used. In particular, in addition to rigidity and dimensional accuracy that can withstand pressure during transfer, and to reduce control inertia and improve control responsiveness, aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, 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 apparatus>
The ink jet recording apparatus according to the present embodiment includes a reaction liquid applying device 103 that applies a reaction liquid to the transfer body 101. 1 is a gravure offset having a reaction solution storage unit 103a that stores a reaction solution, and reaction solution application members 103b and 103c that apply the reaction solution in the reaction solution storage unit 103a onto the transfer body 101. The case of a roller is shown.
<Ink application device>
The ink jet recording apparatus according to this embodiment includes an ink applying device 104 that applies ink to the transfer body 101 to which the reaction liquid is applied. The reaction liquid and the ink are mixed to form a first image, and the next liquid absorbing device 105 absorbs the aqueous liquid component from the first image.

<Liquid absorber>
In the present embodiment, the liquid absorbing device 105 includes a liquid absorbing member 105 a and a pressure member 105 b that presses the liquid absorbing member 105 a against the first image on the transfer body 101. Further, the liquid absorbing member 105a has a first surface as a liquid absorbing surface made of a porous body and a second surface facing the first surface.
The pressure member 105b is actuated to pressurize the second surface of the liquid absorbing member 105a, thereby bringing the first surface into contact with the outer peripheral surface of the transfer body 101, thereby forming a first nip portion. By passing the first image and the liquid absorbing member 105a in contact with the first image through the first nip portion, the liquid absorption processing from the first image can be performed. An area that allows the liquid absorbing member 105a to come into pressure contact with the outer peripheral surface of the transfer body 101 is used as a liquid absorption processing area.
The position of the pressing member 105b with respect to the transfer body 101 and the pressurization to the transfer 101 can be adjusted by position control and a pressurizing mechanism (not shown). For example, the liquid can be reciprocated in the direction of arrow A shown in FIG. The liquid absorbing member 105a can be brought into contact with the outer peripheral surface of the transfer body 101 at a timing when processing is required, and can be separated from the outer peripheral surface.
In addition, there is no restriction | limiting in particular about the shape of the liquid absorption member 105a and the pressurization member 105b. For example, as shown in FIG. 1, the pressure member 105 b has a cylindrical shape, the liquid absorbing member 105 a has a belt shape, and the belt-shaped liquid absorbing member 105 a is transferred to the transfer body 101 by the cylindrical pressure member 105 b. The structure which presses may be sufficient. Further, the pressure member 105b has a columnar shape, and the liquid absorbing member 105a has a cylindrical shape formed on the peripheral surface of the columnar pressure member 105b, and the columnar pressure member 105b has a cylindrical shape. The structure which presses the absorption member 105a against a transfer body may be sufficient.
In the present invention, the liquid absorbing member 105a is preferably belt-shaped in consideration of the space in the ink jet recording apparatus.
Further, the liquid absorbing device 105 having such a belt-shaped liquid absorbing member 105a may have a stretching member that stretches the liquid absorbing member 105a. In FIG. 1, 105c, 105d, and 105e are tension rollers as tension members. These rollers and a belt-shaped liquid absorbing member 105a stretched around these rollers constitute a transport unit that transports a porous body that performs liquid absorption processing from the first image. By this transport unit, it is possible to carry in, carry out, and retransmit the porous body into the liquid absorption processing region.
In FIG. 1, the pressing member 105b is also a roller member that rotates in the same manner as the stretching roller, but is not limited to this.
In the liquid absorbing device 105, the liquid absorbing member 105a having a porous body is pressed against the first image by the pressurizing member 105b, so that the liquid absorbing member 105a absorbs the aqueous liquid component contained in the first image, Remove the aqueous liquid component from the first image. As a method of removing the aqueous liquid component in the first image, in addition to the present method of pressing the liquid absorbing member, various other conventionally used methods, for example, a method by heating, a method of blowing low-humidity air, a pressure reduction You may combine a method etc.

Hereinafter, various conditions and configurations in the liquid absorbing device 105 will be described in detail.
(Preprocessing)
Before the liquid absorbing member having a porous body is brought into contact with the image, it is preferable to perform pretreatment by a pretreatment device (not shown) that applies a treatment liquid to the liquid absorbing member. The treatment liquid preferably contains water and a water-soluble organic solvent. The water is preferably water deionized by ion exchange or the like. The type of the 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 invention, the application method is not particularly limited, but immersion or droplet dropping is preferable.

(Pressure condition)
The first nip pressure of the first nip portion formed by the image forming surface of the transfer body 101 and the pressure member 105b allows the liquid in the image to be separated into a solid and liquid in a shorter time and removes the aqueous liquid component from the image. In order to remove, it is preferably 0.3 kg / cm ² or more. Further, since the transfer body 101 has the characteristics (I) and (II) described above, the first nip pressure is 0.5 which is suitable for both good absorption of the aqueous liquid and prevention of ink transfer. It can be set in the range of ˜3 kg / cm ² .
The first nip pressure is measured with a surface pressure distribution measuring device (I-SCAN manufactured by Nitta Co., Ltd.) for the nip formed by the image forming surface of the transfer member and the liquid absorbing member. Then, the weight in the pressurization region was divided by the area to calculate the value.
(Action time)
The working time for bringing the liquid absorbing member 105a into contact with the first image is preferably within 50 ms in order to further suppress adhesion of the coloring material in the image to the liquid absorbing member. In addition, it is preferable that the action time be 3 ms or longer because the liquid absorbing member 105a can be stably brought into contact with the first image. The operation time in the present invention is calculated by dividing the pressure sensing width in the moving direction of the transfer body 101 in the surface pressure measurement described above by the moving speed of the transfer body 101.
(Method for removing liquid from the liquid absorbing member)
The aqueous liquid component absorbed in the liquid absorbing member from the image can be removed from the liquid absorbing member 105a by a known means. Examples include a method by heating, a method of blowing low-humidity air, a method of reducing pressure, and a method of squeezing a porous body.

  In this way, the aqueous liquid component is absorbed from the first image on the transfer body 101, and a second image with a reduced liquid content is formed. The second image is then transferred onto the recording medium 108 at the transfer portion. The apparatus configuration and conditions during transfer will be described below.

<Transfer unit>
In the present embodiment, there is provided means for transferring the second image on the transfer body 101 onto the recording medium 108 conveyed by the recording medium conveying device 107 by being brought into pressure contact with the recording medium 108 by the transfer member 106. By removing the aqueous liquid component contained in the first 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. In the present embodiment, the transfer unit is configured to include a transfer member 106 and a cylindrical support member 102, that is, a transfer body 101 supported by the outer peripheral surface of the cylindrical support.
A second nip portion is formed by the transfer member 106 and the transfer body 101, and the second image is brought into close contact with the recording medium by passing the second nip portion through the recording medium in contact with the second image. Then, the image is transferred onto the recording medium 108 by pulling the recording medium 108 away from the transfer body 101.
The transfer member 106 is required to have a certain degree of structural strength from the viewpoint of conveyance accuracy and durability of the recording medium 108. The material of the transfer member 106 is preferably a metal, ceramic, resin, or the like. In particular, in addition to rigidity and dimensional accuracy that can withstand pressure during transfer, and to reduce control inertia and improve control responsiveness, aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, Polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, and alumina ceramics are preferably used. Moreover, you may use combining these.
The shape of the transfer member 106 is not particularly limited, and can be selected from various shapes as long as transfer onto a target recording medium is possible. A roller-shaped transfer member as illustrated is suitable for performing high-speed transfer processing in a compact apparatus configuration.
(Action time)
There is no particular limitation on the time for which the second image on the transfer body 101 is pressed against the recording medium 108, but 5 ms or more and 100 ms or less in order to perform transfer well and not impair the durability of the transfer body. It is preferable that The pressure contact time in the present invention indicates the time during which the recording medium 108 and the transfer body 101 are in contact with each other, and the surface pressure is measured with a surface pressure distribution measuring instrument (I-SCAN manufactured by Nitta Co., Ltd.). Then, the length in the conveyance direction of the pressurizing region was divided by the conveyance speed to calculate a value.
(Pressure condition)
The second nip pressure that presses the second image on the transfer body 101 against the recording medium 108 is not particularly limited, but the transfer is performed satisfactorily and the durability of the transfer body is not impaired. Since the transfer body 101 has the characteristics (I) and (II) described above, the second nip pressure is set to a range of 3 to 30.0 kg / cm ² , preferably 5 to 30.0 kg / cm ^2. Further, in this nip pressure range, the second nip pressure can be set to be larger than the first nip pressure, in particular, three times or more the first nip pressure.
The second nip pressure is measured with a surface pressure distribution measuring device for the nip formed by the surface layer of the transfer member and the transfer member, and the weight in the pressurizing region is divided by the area. The value is calculated.
The temperature at which the second image on the transfer body 101 is pressed against the recording medium 108 is not particularly limited, but is preferably at least the glass transition point or the softening point of the resin component contained in the ink. In addition, the heating preferably includes a heating device that heats the second image on the transfer body 101, the transfer body 101, and the recording medium 108.

<Recording medium and recording medium conveying apparatus>
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 a long product wound in a roll shape, or a single sheet cut into a predetermined size. Examples of the material 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 constituted by a recording medium feeding roller 107a and a recording medium take-up roller 107b. It is not limited to.
<Control system>
The transfer type inkjet recording apparatus in the present embodiment has a control system that controls each apparatus. FIG. 2 is a block diagram showing a control system of the entire apparatus in the transfer type ink jet recording apparatus shown in FIG.
In FIG. 2, 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 performing a recording process, and 304 is a recording medium for conveying the recording medium. A conveyance control unit 305 is an inkjet device for printing.
FIG. 3 is a block diagram of a printer control unit in the transfer type inkjet recording apparatus of FIG.
A CPU 401 controls the entire printer, a ROM 402 stores a control program for the CPU, and a RAM 403 executes the program.
Reference numeral 404 denotes an application specific integrated circuit (ASIC) that includes a network controller, a serial IF controller, a head data generation controller, a motor controller, and the like. Reference numeral 405 denotes a liquid absorption member conveyance control unit for driving the liquid absorption member conveyance motor 406, which is command-controlled from the ASIC 404 via the serial IF. Reference numeral 407 denotes a transfer body drive control unit for driving the transfer body drive motor 408, which is similarly command-controlled from the ASIC 404 via the serial IF. Reference numeral 409 denotes a head controller that performs final ejection data generation, drive voltage generation, and the like of the inkjet device 305.

Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following examples as long as the gist thereof is not exceeded. In the description of the following examples, “part” is based on mass unless otherwise specified.
Example 1
In this embodiment, the transfer type ink jet recording apparatus shown in FIG. 1 was used.
<Transfer>
The transfer body 101 in this embodiment is fixed to the support member 102 with an adhesive.
As the transfer body 101, a blanket having an outer peripheral portion having a four-layer structure shown in FIG. 4 was used. The transfer body shown in FIG. 4 has a structure in which a second compressed layer 42, a first compressed layer 41, and a surface layer 40 are laminated on a support layer 43 in this order. Each layer is bonded by an adhesive.
The surface layer 40 was formed of silicone rubber (KE12 manufactured by Shin-Etsu Chemical Co., Ltd.) having a compression elastic modulus of 2 MPa and a thickness of 0.15 mm.
For the first compression layer 41, a foamed urethane rubber having a compression elastic modulus of 0.6 MPa corresponding to the nip pressure in the liquid absorption process and having a thickness of 0.2 mm (Clara foam manufactured by Kurashiki Boseki Co., Ltd.) was used. For the second compression layer 42, foamed urethane rubber (Clara foam manufactured by Kurashiki Boseki Co., Ltd.) having a thickness of 0.3 mm and having a compression elastic modulus of 5 MPa corresponding to the nip pressure in the transfer process was used.
Each compressed layer can be formed by a known material and method. For example, it is possible to use a foaming method in which a foaming agent is blended in a urethane rubber compound for forming a compression layer, molded into a desired sheet shape, and foamed to porous using a foaming agent. The compression elastic modulus of the foamed urethane rubber can be controlled by the material composition, the degree of cure, the firing rate, and the like.
The blanket nip pressure-crush amount curve used in this example is as shown in FIG. 5, and its second derivative is as shown in FIG. The crushing amount at the point α that takes the maximum value when second-order differentiation was performed was 0.4 mm, and the nip pressure was about 4 kg / cm ² .
<Reaction solution>
The composition of the reaction liquid applied to the transfer body 101 by the reaction liquid application device 103 is as follows, and the application amount was 1 g / m ² .
Reaction solution composition:
・ Glutaric acid: 21.0 parts ・ Glycerin: 5.0 parts ・ Surfactant (product name: Megafac F444, manufactured by DIC Corporation): 5.0 parts ・ Ion-exchanged water: remainder <Preparation of ink>
The ink was prepared according to the following procedure.
(1) Preparation of Pigment Dispersion A mixture of the following components was charged into a batch type vertical sand mill (manufactured by IMEX).
Carbon black (product name: Monac 1100, manufactured by Cabot) 10 partsResin aqueous solution (styrene-ethyl acrylate-acrylic acid copolymer, acid value 150, weight average molecular weight (Mw) 8,000, resin content 20.0% by mass aqueous solution neutralized with potassium hydroxide aqueous solution): 15 parts / pure water 75 parts The mixture thus obtained was filled with 200 parts of 0.3 mm diameter zirconia beads and cooled with water. Time dispersion processing was performed. This dispersion was centrifuged to remove coarse particles, and then a black pigment dispersion having a pigment content of 10.0% by mass was obtained.
(2) Preparation of resin particle dispersion 20 parts of ethyl methacrylate, 3 parts of 2,2′-azobis- (2-methylbutyronitrile) and 2 parts of n-hexadecane were mixed and stirred for 0.5 hour. This mixture was added dropwise to 75 parts of an 8% aqueous solution of a styrene-butyl acrylate-acrylic acid copolymer (acid value: 130 mgKOH / g, weight average molecular weight (Mw): 7,000) and stirred for 0.5 hour. did. Next, the ultrasonic wave was irradiated for 3 hours with the ultrasonic irradiation machine. Subsequently, a polymerization reaction was performed in a nitrogen atmosphere at 80 ° C. for 4 hours, and after cooling at room temperature, filtration was performed to prepare a resin particle dispersion having a resin content of 25.0% by mass.
(3) Preparation of ink The resin particle dispersion and the pigment dispersion obtained above were mixed with the following components. The balance of ion-exchanged water is such that the total of all components constituting the ink is 100.0% by mass.
Black pigment dispersion (coloring material content is 10.0% by mass): 40.0% by mass
-Resin particle dispersion: 20.0 mass%
・ Glycerin: 7.0% by mass
Polyethylene glycol (number average molecular weight (Mn): 1,000): 3.0% by mass
Surfactant [acetylene E100 (manufactured by Kawaken Fine Chemical Co., Ltd.)]: 0.5% by mass
-Ion-exchanged water: remainder After the obtained mixture was sufficiently stirred and dispersed, pressure filtration was performed with a micro filter (manufactured by Fuji Film Co., Ltd.) having a pore size of 3.0 µm to prepare a black ink.

<Image formation>
An image was transferred onto a recording medium using the following image forming conditions to obtain a printed matter.
The surface of the transfer body 101 is set to 60 ° C. by a heating means (not shown).
As the ink application device 104, an ink jet device of an ink discharge type using an electro-thermal conversion element was used, and a solid image was formed with an ink application amount of 20 g / m ² .
The liquid absorbing member 105a is adjusted to have a speed equivalent to the moving speed of the transfer body 101 by conveying rollers 105c, 105d, and 105e that convey the liquid absorbing member while stretching it. Further, the recording medium 108 is conveyed by the recording medium feeding roller 107a and the recording medium take-up roller 107b so that the speed is equal to the moving speed of the transfer body 101. In this example, the conveyance speed was 0.5 m / s, and aurora-coated paper (manufactured by Nippon Paper Industries Co., Ltd., basis weight 104 g / m ² ) was used as the recording medium 108.
The nip pressure between the transfer member 101 and the liquid absorbing member 105a is applied to the liquid absorbing member 105b so that the average pressure is 2 kg / cm ² . Further, the pressure member 105b in the liquid absorbing device was a roller having a diameter of 200 mm.
As the liquid absorbing member 105a, a hydrophilic PTFE film having an average pore diameter of 0.2 μm was used. The absorbing member had a galee of 8 seconds.
In the liquid absorption process, the blanket was crushed in an amount of 0.2 mm, and the nip pressure at that time was about 2 kg / cm ² . In the transfer process, the blanket was used at a crushing amount of 0.7 mm, and the nip pressure at that time was about 15 kg / cm ² . As described above, the liquid removal step was performed in a range where the squeezing amount was smaller than the point α that had the maximum value when second-order differentiation was performed in the nip pressure-squeezing amount curve, and the transfer step was performed in the range where the squeezing amount was large.
(Reference Example 1)
Using the blanket described in Example 1, the blanket collapse amount is set to 0.2 mm in the liquid absorption process, the nip pressure is about 2 kg / cm ² , and the blanket collapse amount is 0.3 mm in the transfer process. The pressure was used at about 3 kg / cm ² . That is, both the liquid removal step and the transfer step were performed in a range where the crushed amount was smaller than the point α of the blanket nip pressure-crush amount curve shown in FIG. Otherwise, a printed material was obtained in the same manner as in Example 1.
(Reference Example 2)
The blanket described in Example 1 was used, the blanket collapse amount was set to 0.5 mm in the liquid absorption process, the nip pressure at that time was about 8 kg / cm ² , and the blanket collapse amount was 0.7 mm in the transfer process. The nip pressure was about 15 kg / cm ² . That is, both the liquid removal step and the transfer step were performed in a range where the crushed amount was larger than the point α of the blanket nip pressure-crush amount curve shown in FIG. Otherwise, a printed material was obtained in the same manner as in Example 1.
(Reference Example 3)
A printed matter was obtained in the same manner as in Example 1 except that a silicone rubber having a compression modulus of 10 MPa was used for the surface layer.

[Evaluation]
The color material adhesion (color transfer) from the image on the transfer body to the porous body as the liquid absorbing member was evaluated by the area of the area where the color material adhered on the surface of the porous body immediately after the liquid absorption treatment. As an index at that time, a coloring material adhesion rate calculated by the following Equation 1 was used.
Color material adhesion rate (%) = 100 − ((A−B) / A) × 100 (Expression 1)
In Equation 1, A is the area of the first image printed on the blanket, and B is the color material adhesion area on the porous body surface.
Regarding the coloring material adhesion, the criteria for ◯ × are as follows.
○ Color material adhesion rate ≤ 10%
× Color material adhesion rate> 10%
The transferability of the image onto the recording medium was evaluated by the transfer area of the image on the recording medium. As an index at that time, the transfer rate calculated by the following formula 2 was used.
Transfer rate (%) = (D / C) × 100 (Equation 2)
In Equation 2, C is the area printed on the blanket, and D is the area of the image transferred to the recording medium.
For transferability, the criteria for ◯ × were as follows.
○ ... Transfer rate ≧ 90%
× ・ ・ ・ Transfer rate <90%
The printed materials obtained in Example 1 and Reference Examples 1 to 3 were evaluated for colorant adhesion and transferability. The obtained results are shown in Table 1.

That is, from the evaluation results shown in Table 1, in Reference Example 1, since the region of the compression layer having a low compression elastic modulus was used in the transfer process, a sufficient nip pressure was not obtained, and the transfer rate was low. It was. Further, in Reference Example 2, since the region of the compression layer having a high compression elastic modulus was used in the liquid absorption process, the nip pressure became too large, resulting in a large color material adhesion rate. In Reference Example 3, it is assumed that the surface layer cannot sufficiently contact the surface of the recording medium because the compression elastic modulus of the surface layer is large, and a high transfer rate was not obtained in the transfer process.
On the other hand, in Example 1, it is possible to carry out both processes at a suitable nip pressure in the liquid absorption process and the transfer process, and realize an ink jet recording method having both a liquid absorption process with a low color material adhesion rate and a transfer process with a high transfer rate. did it. Therefore, according to the present invention, it is possible to provide an ink jet recording method that realizes a uniform nip pressure for obtaining a high-quality printed matter in both the liquid removal step and the transfer step.

DESCRIPTION OF SYMBOLS 101 Transfer body 102 Support member 104 Ink application apparatus 105 Liquid absorption apparatus 105a Liquid absorption member 105b Pressure member 106 Transfer member 108 Recording medium 40 Surface layer 41 First compression layer 42 Second compression layer 43 Support layer

Claims (23)

An image forming step of forming a first image containing an aqueous liquid component and a coloring material by applying aqueous ink to the image forming surface of the transfer body;
The first image is pressed by the first nip pressure by the surface including the porous body in the first nip portion formed by the surface including the porous body of the liquid absorbing member and the image forming surface. A liquid absorption step in which at least a part of the aqueous liquid component is absorbed by the porous body to form a second image;
A transfer step of bringing the second image and the recording medium into contact with each other at a second nip formed by the image forming surface and the transfer member, and applying a second nip pressure to transfer the image to the recording medium;
An image forming method comprising:
The transfer body includes a compression layer having a plurality of compression elastic moduli and a surface layer including the image forming surface, and against a nip pressure when a nip portion is formed by pressurization from the image forming surface side. It has the maximum value in the second derivative of the function indicating the change in the amount of squashing,
(I) The crushing amount due to the first nip pressure is smaller than the crushing amount that takes the maximum value in the second derivative of the function,
(II) The image forming method, wherein the squashing amount due to the second nip pressure is larger than the squashing amount that takes the maximum value in the second derivative of the function.   The image forming method according to claim 1, wherein the second nip pressure is three times or more the first nip pressure.   3. The image forming method according to claim 1, wherein the plurality of compression elastic moduli of the compression layer includes a first compression elastic modulus and a second compression elastic modulus.   The image forming method according to claim 3, wherein the first compression elastic modulus is 3 MPa or less.   The compression elastic modulus of the surface layer has a third compression elastic modulus smaller than the second compression elastic modulus of the compression layer, and the thickness of the surface layer is smaller than the thickness of the compression layer. The image forming method according to any one of claims 1 to 4.   The transfer body has a cylindrical support and the compression layer and the surface layer on the outer peripheral surface of the cylindrical support, and the image forming step, the liquid are synchronized with the rotation of the cylindrical support. The image forming method according to claim 1, wherein an absorption step and the transfer step are performed.   The image forming method according to claim 1, wherein the water-based ink is applied to the image forming surface of the transfer body by an ink jet method.   The image forming method according to any one of claims 1 to 7, wherein the first image is formed by a reaction liquid containing the water-based ink and a component for increasing the viscosity of the water-based ink. A transcript,
An image forming unit having an ink applying unit for applying a water-based ink to an image forming surface of the transfer body to form a first image including an aqueous liquid component and a coloring material;
A surface including a porous body that forms a first nip portion with the image forming surface, and the first image is formed by a surface including the porous body in the first nip portion by a first nip pressure. A liquid absorbing member that pressurizes and absorbs at least a part of the aqueous liquid component by the porous body to form a second image;
A second nip portion is formed by the image forming surface and the transfer member, the second image and the recording medium are brought into contact with each other at the second nip portion, and the recording medium is pressurized by a second nip pressure. A transfer unit for transferring to
An image forming apparatus comprising:
The transfer body has a compression layer having a plurality of compression elastic moduli and a surface layer including the image forming surface, and against a nip pressure when a nip portion is formed by pressing from the image forming surface side. It has the maximum value in the second derivative of the function indicating the change in the amount of squashing,
(I) The crushing amount due to the first nip pressure is smaller than the crushing amount that takes the maximum value in the second derivative of the function,
(II) The image forming apparatus characterized in that the squashing amount due to the second nip pressure is larger than the squashing amount that takes the maximum value in the second derivative of the function.   The image forming apparatus according to claim 9, wherein the second nip pressure is three times or more the first nip pressure.   11. The image forming apparatus according to claim 9, wherein the plurality of compression elastic moduli of the compression layer includes a first compression elastic modulus and a second compression elastic modulus.   The image forming apparatus according to claim 11, wherein the first compression elastic modulus is 3 MPa or less.   The compression elastic modulus of the surface layer has a third compression elastic modulus smaller than the second compression elastic modulus of the compression layer, and the thickness of the surface layer is smaller than the thickness of the compression layer. The image forming apparatus according to claim 9.   The transfer body has a cylindrical support, and the compression layer and the surface layer on an outer peripheral surface of the cylindrical support, and the image forming unit, the liquid are synchronized with the rotation of the cylindrical support. The image forming apparatus according to claim 9, wherein the absorbing member and the transfer unit operate.   The image forming apparatus according to claim 9, wherein the ink applying unit is an ink applying unit using an ink jet method.   16. The image forming unit according to claim 9, wherein the image forming unit includes a reaction liquid applying unit that applies a reaction liquid containing a viscosity increasing component of the water-based ink to the image forming surface. Image forming apparatus. A transfer material for transfer type image formation using water-based ink,
Nip pressure at the time of forming a nip portion by pressurization from the image forming surface side, having a compression layer having a plurality of compression moduli and a surface layer including an image forming surface for image formation with aqueous ink It has a maximum value in the second derivative of the function indicating the change in the amount of crushing with respect to
(I) The amount of crushing due to the pressure in the range of 0.5 to ³ kg / cm ² is smaller than the amount of crushing taking the maximum value in the second derivative of the function,
(Ii) A transfer body, wherein a crushing amount due to a pressure in a range of 5 to 30.0 kg / cm ² is larger than a crushing amount that takes a maximum value in the second derivative of the function.   The transfer body according to claim 17, wherein the plurality of compression elastic moduli of the compression layer includes a first compression elastic modulus and a second compression elastic modulus.   The transfer body according to claim 18, wherein the first compression elastic modulus is 3 MPa or less.   The compression elastic modulus of the surface layer has a third compression elastic modulus smaller than the second compression elastic modulus of the compression layer, and the thickness of the surface layer is smaller than the thickness of the compression layer. The transfer body according to any one of claims 17 to 19.   The transfer body according to any one of claims 17 to 20, further comprising the compression layer and the surface layer on an outer peripheral surface of a cylindrical support.   The transfer body according to any one of claims 17 to 21, wherein the image formation with the water-based ink is performed by an inkjet method.   The transfer body according to any one of claims 17 to 22, wherein the image formation is performed by a reaction liquid containing the water-based ink and a viscosity-increasing component of the water-based ink.

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