JP2023143154A - Manufacturing method of liquid absorption member - Google Patents

Abstract

To provide a manufacturing method of a liquid absorption member which can suppress deformation of an ink image even if there is a portion with the low liquid permeable property in a porous body.SOLUTION: There is provided a manufacturing method of a liquid absorption member, the liquid absorption member including a porous body 10 in which a plurality of porous layers are laminated, the porous body 10 including a first surface 10a, and liquid permeating in a first direction crossing each porous layer from the first surface 10a. The manufacturing method comprises steps of: forming the porous body 10 including a blocking part 11 in an i (2≤i≤N)-th porous layer when the layer number of the porous layers is N(>2) and the porous layer constituting the first surface 10a is a first porous layer; and applying peeling liquid to the porous body 10, making the peeling liquid enter a region opposed to the blocking part 11 of an interface in at least one interface between the respective porous layers from the first porous layer to the i-th porous layer, applying heat and pressure and forming a peeling region 12 in which the interface is partially peeled in the region.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing a liquid absorbing member that absorbs liquid components from an image made of a liquid composition containing a coloring material.

In the inkjet recording method, an ink image is formed by directly or indirectly applying a liquid composition containing a coloring material (hereinafter also referred to as ink) onto a recording medium such as paper. Curling or cockling may occur if the recording medium absorbs too much of the liquid component in the ink image.
As a method for suppressing excessive liquid absorption into a recording medium, Patent Document 1 describes a method in which a roller-shaped porous body is brought into contact with an ink image to absorb liquid components from the ink image.

Japanese Patent Application Publication No. 2009-45851

In the method described in Patent Document 1, if there are areas in the porous body through which liquid is difficult to pass (areas with low liquid permeability), the ink image is deformed when absorbing the liquid component, resulting in image defects. There are cases. Causes of deterioration of the liquid permeability of a porous body include non-uniform density of the porous body and contamination of foreign matter. Porous bodies having such defects are used while avoiding the defective parts, resulting in poor efficiency.

An object of the present invention is to provide a method for manufacturing a liquid absorbing member that can suppress deformation of an ink image even if there is a portion with low liquid permeability in a porous body.

According to one aspect of the present invention, the porous body has a plurality of laminated porous layers, the porous body has a first surface that absorbs liquid, and each porous layer is formed from the first surface. A method for manufacturing a liquid absorbing member in which a liquid permeates in a first direction that crosses the forming the porous body as a first porous layer, the i-th (2≦i≦N) porous layer having a closing portion that blocks the flow of liquid in the first direction; A stripping liquid is applied to the porous body, and at least one of the interfaces between each porous layer from the first porous layer to the i-th porous layer is opposed to the closed part of the interface. A method for manufacturing a liquid absorbing member, comprising the steps of: infiltrating the stripping liquid into a region where the stripping liquid is applied, and applying heat and pressure to form a stripping region in which the interface is partially stripped in the region. is provided.

According to another aspect of the present invention, the porous body has a plurality of laminated porous layers, the porous body has a first surface that absorbs liquid, and the porous body has a first surface that absorbs liquid. A method for manufacturing a liquid absorbing member in which a liquid permeates in a first direction across the layers, the method comprising: inspecting a porous layer other than a porous layer constituting the first surface; detecting a blockage that blocks the flow of liquid; stacking the plurality of porous layers by applying heat and pressure; A liquid absorption method comprising the step of: forming an internal liquid path by partially peeling off the interface in a region facing the blocking part at least one of the interfaces located on the side of the surface of the liquid absorber. A method of manufacturing a member is provided.

According to the present invention, even if there is a portion with low liquid permeability in a porous body, deformation of an ink image can be suppressed.

FIG. 1 is a schematic diagram showing an example of a schematic configuration of a transfer type inkjet recording device. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining a method for manufacturing a liquid absorbing member, which is an embodiment of the present invention. FIG. 3 is a schematic diagram showing an example of a method for forming a peeled region. FIG. 7 is a schematic diagram showing another example of a method for forming a peeled region. FIG. 7 is a schematic diagram showing yet another example of a method for forming a peeled region. FIG. 3 is a cross-sectional view of a liquid absorbing member that does not have a closed portion and a peeled region. FIG. 2 is a cross-sectional view of a liquid absorbing member in which a closed portion is present in a porous body. FIG. 2 is a schematic diagram showing an example of a liquid absorbing member having a closing portion and a peeling region. FIG. 7 is a schematic diagram showing another example of a liquid absorbing member having a closing portion and a peeling region. FIG. 7 is a schematic diagram showing yet another example of a liquid absorbing member having a closing part and a peeling region. FIG. 1 is a block diagram showing the configuration of a control system for a transfer inkjet recording apparatus. FIG. 2 is a block diagram showing the configuration of a printer control section of the transfer type inkjet recording device. FIG. 1 is a schematic diagram showing an example of a schematic configuration of a direct writing inkjet recording apparatus. FIG. 2 is a block diagram showing the configuration of a printer control section of the direct drawing inkjet recording device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the components described in the embodiments are merely examples, and the scope of the present invention is not intended to be limited thereto.

Examples of inkjet recording apparatuses to which the method of manufacturing a liquid absorbing member of the present invention is applied include the following two types. One is an inkjet recording apparatus that forms an ink image on a transfer body as an ejection target medium, absorbs the liquid component of the ink image using a liquid absorbing member, and then transfers the ink image to a recording medium. The other is an inkjet recording apparatus that forms an ink image on a recording medium such as paper or cloth as a medium to be ejected, and uses a liquid absorbing member to absorb the liquid component of the ink image. In the following description, for convenience, the former inkjet recording device will be referred to as a transfer type inkjet recording device, and the latter inkjet recording device will be referred to as a direct drawing type inkjet recording device.
In the following, first, the configuration of a transfer type inkjet recording apparatus, as well as the configuration and manufacturing method of a liquid absorbing member that is an embodiment of the present invention will be specifically explained, and then the configuration of a direct drawing type inkjet recording apparatus will be explained. do.

<Transfer type inkjet recording device>
FIG. 1 is a schematic diagram showing an example of a schematic configuration of a transfer type inkjet recording apparatus. The inkjet recording apparatus 100 is a sheet-fed inkjet recording apparatus that produces a recorded matter by transferring an ink image onto a recording medium 108 via a transfer body 101. In FIG. 1, the X direction, Y direction, and Z direction indicate the width direction (total length direction), depth direction, and height direction of the inkjet recording apparatus 100, respectively. The recording medium 108 is conveyed in the direction of arrow C (corresponding to the X direction).

The inkjet recording apparatus 100 includes a reaction liquid applying device 103 , an ink applying device 104 , a liquid absorbing device 105 , a pressing member 106 , and a recording medium conveying device 107 . The transfer body 101 is supported by a support member 102 and rotates in the direction of arrow A around a rotation axis 102a of the support member 102. The reaction liquid applying device 103 , the ink applying device 104 , the liquid absorbing device 105 , the pressing member 106 , and the recording medium conveying device 107 are arranged along the outer periphery of the transfer body 101 .

The reaction liquid application device 103 applies a reaction liquid that reacts with color ink onto the transfer body 101 . The ink applying device 104 applies colored ink onto the transfer body 101 to which the reaction liquid has been applied. The liquid absorption device 105 absorbs liquid components from the ink image on the transfer body 101. The pressing member 106 presses the surface of the transfer body 101 on which the ink image is formed toward a recording medium 108 such as paper. When the pressing member 106 presses the transfer body 101, the ink image is transferred onto the recording medium 108. The ink image transferred onto the recording medium 108 is an inverted image of the ink image on the transfer body 101.

Further, the inkjet recording apparatus 100 may include a transfer body cleaning member 109 that cleans the surface of the transfer body 101 as necessary. The transfer body 101, the reaction liquid application device 103, the ink application device 104, the liquid absorption device 105, and the transfer body cleaning member 109 each have a width in the Y direction equal to the width of the recording medium 108 (recordable width). handle.

Each configuration of the inkjet recording apparatus 100 will be described below.
<Transfer body 101>
The transfer body 101 has a surface layer including an image forming surface on which an ink image is formed. As the material for the surface layer, resin, ceramic, etc. can be used as appropriate. From the viewpoint of durability and the like, it is preferable to form the surface layer using a material having a high compressive modulus. Examples of materials having a high compressive modulus include acrylic resins, acrylic silicone resins, fluorine-containing resins, and condensates obtained by condensing hydrolyzable organosilicon compounds. In order to improve the wettability, transferability, etc. of the reaction solution, it may be used after surface treatment. 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, silane coupling treatment, and the like. A plurality of these processes may be combined. Further, the surface layer can also be provided with an arbitrary surface shape.

Furthermore, the transfer body 101 may include a compression layer that has a function of absorbing pressure fluctuations. By absorbing deformation, the compressed layer can disperse local pressure fluctuations. Thereby, good transferability can be maintained during high-speed printing.
Further, the transfer body 101 may include an elastic layer or a reinforcing layer having a high compressive elastic modulus between the surface layer and the compressed layer. As the material of the elastic layer, resin, ceramic, etc. can be used as appropriate. A woven fabric may be used for the reinforcing layer.
The transfer body 101 may be freely produced by combining the above-mentioned layers in any manner according to the size of the intended print image. Each layer (surface layer, elastic layer, compression layer) may be fixed using adhesive or double-sided tape. Examples of the shape of the transfer body 101 include, but are not limited to, a sheet shape, a roller shape, a belt shape, an endless web shape, and the like.

<Support member 102>
The material of the support member 102 is metal, ceramic, resin, etc. Specific examples include aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, alumina ceramics, and the like. It is preferable to form the support member 102 by combining these members.
The transfer body 101 may be fixed to the support member 102 using various adhesives or double-sided tape. Further, the transfer body 101 may be fixed to the support member 102 using an installation member. The installation member is, for example, metal, ceramic, resin, or the like.

<Reaction liquid application device 103>
The reaction liquid application device 103 includes a reaction liquid storage section 103a that stores a reaction liquid, and reaction liquid application members 103b and 103c that apply the reaction liquid stored in the reaction liquid storage section 103a to the transfer body 101. The reaction liquid application device 103 only needs to be capable of applying the reaction liquid onto the transfer body 101, and various conventionally known devices may be used. Specifically, 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 reaction liquid applying device 103 shown in FIG. 1 is a gravure offset roller.

Application of the reaction liquid by the reaction liquid application device 103 may be performed before or after application of the ink, as long as it can be mixed (reacted) with the ink on the transfer body 101. Preferably, the reaction liquid is applied before the ink is applied. By applying a reaction liquid before ink application, during inkjet image recording, problems such as bleeding where adjacently applied inks mix with each other and beads that land first and are attracted to later inks can be avoided. It is possible to suppress the

<Reaction solution>
The reaction liquid contains a component that increases the viscosity of the ink (ink viscosity increasing component). Increasing the viscosity of the ink includes cases where an increase in the viscosity of the entire ink is observed and cases where the viscosity increases locally. The ink viscosity increasing component reduces the fluidity of part of the ink and/or ink composition on the transfer body 101, and therefore has the effect of suppressing bleeding and beading during image formation with the ink.
The reaction liquid may contain multiple types of ink viscosity increasing components. Further, the reaction solution can contain an appropriate amount of water or a low-volatility organic solvent. Furthermore, the reaction solution can be used by adding a surfactant or a viscosity modifier to adjust its surface tension and viscosity as appropriate.

<Ink application device 104>
The ink application device 104 includes an inkjet head that ejects ink. The inkjet head may have any form as long as it can eject ink. Examples of inkjet head formats include, for example, one that uses an electro-thermal converter to cause film boiling in the ink to form bubbles to eject ink, one that uses an electro-mechanical converter to eject ink, and one that uses static electricity to eject ink. Examples include a form in which ink is ejected by From the viewpoint of realizing high-speed, high-density printing, it is preferable to use a form that utilizes an electro-thermal converter.
In this embodiment, the inkjet head is a full-line head extending in the Y direction, and the ejection ports are arranged in a range that covers the width of the image recording area of the maximum usable recording medium 108. . The inkjet head has an ejection surface in which ejection ports are opened on the lower surface (the surface on the transfer body 101 side). The ejection surface faces the surface of the transfer body 101 with a small gap (on the order of several millimeters).

The ink application device 104 may have a plurality of inkjet heads in order to apply color inks of a plurality of colors onto the transfer body 101. For example, when forming images of each color using yellow ink, magenta ink, cyan ink, and black ink, the ink applying device 104 has four inkjet heads corresponding to each color. These inkjet heads are arranged along the X direction.
Further, the ink applying device 104 may include an inkjet head that does not contain a coloring material, or even if it does contain a coloring material, the proportion thereof is very low and that discharges substantially transparent clear ink. The clear ink can be used together with the reaction liquid and color ink to form an ink image. For example, clear ink can be used to improve the gloss of an image. In addition to gloss, clear ink may also be used to improve the transferability of images from the transfer body 101 to the recording medium 108.

<Ink>
The components of the ink will be explained.
<Color material>
As the coloring material contained in the ink, a pigment or a mixture of a dye and a pigment can be used. The type of pigment used as a coloring material is not particularly limited. Specific examples of pigments include inorganic pigments such as carbon black, and organic pigments such as azo-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, imidazolone-based, diketopyrrolopyrrole-based, and dioxazine-based pigments. These pigments can be used alone or in combination of two or more, if necessary.

The type of dye used as the coloring material is not particularly limited. Specific examples of the dye include direct dyes, acid dyes, basic dyes, disperse dyes, and food dyes, and dyes having anionic groups 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, an anthrapyridone skeleton, and the like.
The pigment content in the ink is preferably 0.5% by mass or more and 15.0% by mass or less, more preferably 1.0% by mass or more and 10.0% by mass or less based on the total mass of the ink. .

<Dispersant>
As the dispersant for dispersing the pigment, known dispersants used in inkjet inks can be used. For example, a water-soluble dispersant having both a hydrophilic part and a hydrophobic part can be used. Further, a pigment dispersant made of a copolymerized resin containing at least a hydrophilic monomer and a hydrophobic monomer may be used. Note that there are no particular limitations on each monomer, and known monomers can be suitably used. Specifically, examples of the hydrophobic monomer include styrene and other styrene derivatives, alkyl (meth)acrylate, benzyl (meth)acrylate, and the like. Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, and maleic acid.

The acid value of the dispersant is preferably 50 mgKOH/g or more and 550 mgKOH/g or less. The weight average molecular weight of the dispersant is preferably 1,000 or more and 50,000 or less. The mass ratio of the pigment to the dispersant (pigment:dispersant) is preferably in the range of 1:0.1 to 1:3.
Alternatively, a so-called self-dispersing pigment, which is made dispersible by surface modification of the pigment itself, may be used without using a dispersant.

<Resin fine particles>
The ink may contain various fine particles without coloring material. In particular, fine resin particles are preferably included in the ink in order to improve image quality and fixing properties.
The material of the resin fine particles is not particularly limited, and any known resin can be used as appropriate. Specifically, homopolymers such as polyolefin, polystyrene, polyurethane, polyester, polyether, polyurea, polyamide, polyvinyl alcohol, poly(meth)acrylic acid and its salts, poly(meth)alkyl acrylate, polydiene, or , and copolymers obtained by polymerizing a combination of 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 or more and 2,000,000 or less. Further, the amount of 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, based on the total mass of the ink.

Further, a resin particle dispersion in which resin particles are dispersed in a liquid may be used. There are no particular restrictions on the method of dispersion. A so-called self-dispersing resin fine particle dispersion, which is obtained by dispersing a resin made by homopolymerizing or copolymerizing a plurality of monomers having a dissociable group, is preferable. Examples of dissociable groups include carboxyl groups, sulfonic acid groups, phosphoric acid groups, and the like. Examples of monomers having such a dissociable group include acrylic acid and methacrylic acid. Furthermore, a so-called emulsion-dispersion type resin fine particle dispersion in which fine resin particles are dispersed with an emulsifier can also be used. As the emulsifier, known surfactants are preferred, regardless of whether they have a low molecular weight or a 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 size of 10 nm or more and 1000 nm or less, more preferably 100 nm or more and 500 nm or less.
When producing the resin fine particle dispersion, various additives may be added for stabilization. Examples of additives include n-hexadecane, dodecyl methacrylate, stearyl methacrylate, chlorobenzene, dodecyl mercaptan, blue dye (bluing agent), polymethyl methacrylate, and the like.

<Surfactant>
The ink may also include a surfactant. Examples of the surfactant include acetylene glycol ethylene oxide adduct (Acetylenol E100, manufactured by Kawaken Fine Chemical Co., Ltd.). The amount of surfactant in the ink is preferably 0.01% by mass or more and 5.0% by mass or less based on the total mass of the ink.

<Water and water-soluble organic solvent>
The ink can contain water and/or a water-soluble organic solvent as a solvent. Water deionized by ion exchange or the like may also be used. The content of water in the ink is preferably 30% by mass or more and 97% by mass or less based on the total mass of the ink.
The type of water-soluble organic solvent 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, and ethanol. , methanol, etc. Two or more types selected from these may be used in combination.
Further, the content of the water-soluble organic solvent in the ink is preferably 3% by mass or more and 70% by mass or less based on the total mass of the ink.

<Other additives>
In addition to the above ingredients, the ink may also contain pH adjusters, rust preventives, antiseptics, antifungal agents, antioxidants, antireduction agents, water-soluble resins and their neutralizing agents, viscosity modifiers, etc., as necessary. It may contain various additives.

<Liquid absorption device 105>
The liquid absorbing device 105 includes a liquid absorbing member 105a, a pressing member 105b, and a plurality of tension rollers 105c. The liquid absorbing member 105a is manufactured using a method for manufacturing a liquid absorbing member that is an embodiment of the present invention. The liquid absorbing member 105a is made of a porous material and absorbs liquid components from the ink image. The liquid absorbing member 105a is shaped like an endless belt, and a plurality of tension rollers 105c are in contact with the front and back surfaces of the belt. The liquid absorbing member 105a rotates in the direction of arrow B.

The tip of the pressing member 105b has a hemispherical shape. The tip of the pressing member 105b comes into contact with the back surface of the liquid absorbing member 105a. In this state, the pressing member 105b presses the liquid absorbing member 105a toward the transfer body 101. The liquid absorbing member 105a is pressed against the ink image on the transfer body 101 by the pressure of the pressing member 105b.
Note that the shapes of the liquid absorbing member 105a and the pressing member 105b are not limited to the shapes shown in FIG. For example, the pressing member 105b may be a roller member that rotates like a tension roller. In this case, the pressing member 105b has a cylindrical shape, and the liquid absorbing member 105a is formed on the outer peripheral surface of the pressing member 105b. The liquid absorbing member 105a formed on the pressing member 105b is pressed against the transfer body 101. However, from the viewpoint of effectively utilizing the space within the inkjet recording apparatus 100, it is preferable that the liquid absorbing member 105a has a belt shape.

In the liquid absorption device 105, the liquid absorption member 105a is pressed against the ink image by the pressing member 105b, and the liquid component contained in the ink image is absorbed by the liquid absorption member 105a. The ink image after the liquid removal, in which the liquid component has been removed, has more concentrated ink than the ink image before the liquid removal. The state in which the ink is concentrated means that as the liquid component contained in the ink decreases, the content ratio of solid components such as coloring materials and resins contained in the ink to the liquid component increases.
The liquid absorbing member 105a moves in conjunction with the movement of the transfer body 101, comes into contact with an ink image, and then comes into contact with another ink image again at a predetermined period. As a method for reducing the liquid component in the ink image, in addition to the liquid absorbing member 105a, various conventionally used methods, such as a heating method, a method of blowing low-humidity air, a method of reducing pressure, etc., may be combined. For example, after reducing the liquid component in the ink image using the liquid absorbing member 105a, various conventional methods are applied to further reduce the liquid component in the ink image.

<Press member 106>
The pressing member 106 has a roller shape and presses the recording medium 108 conveyed by the recording medium conveying means 107 toward the transfer body 101 . Due to the pressing action of the pressing member 106, the ink image on the transfer body 101 is brought into contact with the recording medium 108. As a result, the ink image is transferred to the recording medium 108. From the viewpoint of conveyance accuracy and durability of the recording medium 108, it is preferable to use metal, ceramic, resin, or the like as the material of the pressing member 106. Specific examples include aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, alumina ceramics, and the like. You may use these in combination.

The pressing time during which the pressing member 106 presses the transfer body 101 is preferably, for example, 5 ms or more and 100 ms or less. The pressing time indicates the time during which the recording medium 108 and the transfer body 101 are in contact with each other. The pressure with which the pressing member 106 presses the transfer body 101 is preferably, for example, 0.1 MPa or more and 3 MPa or less. This pressure corresponds to the nip pressure between the recording medium 108 and the transfer body 101. The temperature at which the pressing member 106 presses the transfer body 101 is preferably higher than the glass transition point or higher than the softening point of the resin component contained in the ink. Note that the shape of the pressing member 106 is not limited to the roller shape.

<Recording medium 108 and recording medium transport device 107>
The recording medium transport device 107 includes a feed roller 107a and a take-up roller 107b. The recording medium 108 is wound into a roll, and is attached to a feeding roller 107a. The recording medium 108 fed out from the feeding roller 107a is wound up by the winding roller 107b.
The recording medium 108 is not limited to being wound into a roll. The recording medium 108 may be in the form of sheets cut into predetermined dimensions. In this case, the recording medium conveying device 107 is configured to be able to convey a sheet of recording medium 108.
Examples of the material of the recording medium 108 include paper, plastic film, wood board, cardboard, and metal film.
The above is the explanation of each component of the transfer type inkjet recording apparatus.

Next, a method for manufacturing the liquid absorbing member 105a, which is an embodiment of the present invention, will be described. Below, first, the structure of the liquid absorbing member 105a manufactured by this manufacturing method will be explained, and then the manufacturing procedure of the liquid absorbing member 105a will be specifically explained.
<Liquid absorbing member 105a>
FIG. 2 is a schematic diagram showing the configuration of the liquid absorbing member 105a. Referring to FIG. 2, the liquid absorbing member 105a includes a porous body 10 in which a plurality of porous layers are laminated. The porous body 10 includes a first surface 10a that absorbs liquid, and is configured such that the liquid permeates from the first surface 10a in a first direction (arrow A) across each porous layer. . The first surface 10a is a surface that comes into contact with the ink image on the transfer body 101.

The number of porous layers is N (>2), and the porous layer forming the first surface 10a is the first porous layer. The i-th (2≦i≦N) porous layer has a closing portion 11 that blocks the flow of liquid in the first direction (arrow A). N can be expressed as a natural number of 2 or more. In a region of the interface 10c between the first porous layer and the second porous layer that faces the closed portion 11, there is a peeled area 12 where the interface 10c is partially peeled off.
When the porous body 10 is viewed from a direction perpendicular to the first surface 10a, the peeled region 12 preferably overlaps at least a portion of the closed portion 11, and preferably overlaps the entire closed portion 11. is more preferable. Note that the interface forming the peeling region 12 is not limited to the interface 10c between the first porous layer and the second porous layer. The peeling region 12 may be formed at at least one of the interfaces between the respective porous layers from the first porous layer to the i-th porous layer.

<Porous body 10>
In the porous body 10, it is preferable that the average pore diameter of the pores on the first surface 10a side is smaller than the average pore diameter of the pores on the second surface 10b side, which is the surface opposite to the first surface 10a. The second surface 10b corresponds to the surface of the Nth porous layer. For example, among the porous layers constituting the porous body 10, the average pore diameter of the first porous layer is made the smallest. In order to prevent the coloring material in the ink from adhering to the porous body 10, the pore diameter of the porous body 10 is preferably small, and the average pore diameter at least on the first surface 10a side is preferably 10 μm or less. . In this embodiment, the average pore diameter refers to the average diameter of each pore on the first surface 10a or the surface of the porous layer. The average diameter of each pore can be measured by known means, such as mercury intrusion method, nitrogen adsorption method, and SEM image observation.

The reason why the average pore diameter on the first surface 10a side is made smaller than the average pore diameter on the second surface 10b side will be briefly explained below. The following three functions are mainly required for the first surface 10a.
(1) To absorb the liquid component from the ink image on the transfer body 101 in a short time (2) To prevent the ink image on the transfer body 101 from deteriorating (deforming) (3) To reduce cleaning, the first surface 10a In order for the porous body 10 to quickly absorb the liquid component of the ink image in a short time, it is preferable that the pore diameter of the porous body 10 be large. However, when the pore diameter of the porous body 10 is increased, the surface roughness of the first surface 10a of the porous body 10 increases, so that ink tends to adhere to the first surface 10a of the porous body 10. As a result, problems such as an increase in the frequency of cleaning the first surface 10a of the porous body 10 arise. On the other hand, if the pore diameter of the porous body 10 is made small, it becomes difficult to absorb the liquid component of the ink image in a short time. As a result, since the first surface 10a of the porous body 10 is brought into contact with the ink image in which the liquid component has not been sufficiently removed while being pressurized, the image is likely to deteriorate (deform).
Considering the above characteristics, in order to prevent the ink image from deteriorating and to reduce the frequency of cleaning, the average pore diameter of the first surface 10a is made small, and in order to quickly absorb the liquid component from the ink image, It is preferable to increase the average pore diameter of the second surface 10b.

Further, in order to obtain uniform high air permeability throughout the porous body 10, it is preferable to reduce the thickness of the porous body 10. Air permeability can be expressed by the Gurley value defined in JIS P8117. The Gurley value of the porous body 10 is preferably 10 seconds or less.
However, if the porous body 10 is made too thin, it may not be possible to sufficiently secure the capacity necessary to absorb the liquid component. Therefore, in this embodiment, the porous body 10 is a laminate of N layers, and the first porous layer is formed thinner than the other porous layers. In other words, among the porous layers constituting the porous body 10, the first porous layer has the thinnest thickness. Note that the liquid absorbing member 105a may include members other than the porous body 10.

Next, each porous layer of the porous body 10 will be explained in detail. Below, the first porous layer, the second porous layer, and the third porous layer when the number of layers N is 3 will be explained in order. Note that in this specification, the first porous layer may be referred to as an "absorption layer", and the second and subsequent porous layers may be referred to as a "support layer".

<First porous layer>
The material of the first porous layer is not particularly limited, and either a hydrophilic material with a contact angle of less than 90° to water or a water-repellent material with a contact angle of 90° or more may be used. I can do it.
The hydrophilic material is preferably selected from a single material such as cellulose or polyacrylamide, or a composite material thereof. Furthermore, the following water-repellent materials can also be used after the surface is treated to make them hydrophilic. Examples of the hydrophilic treatment include methods such as sputter etching, radiation or H2O ion irradiation, and excimer (ultraviolet) laser light irradiation.
In the case of a hydrophilic material, it is more preferable that the contact angle with respect to water is 60° or less. By using a hydrophilic material, it is possible to obtain the effect of sucking up liquid, especially water, by capillary force.

On the other hand, in order to suppress adhesion of coloring material and improve cleaning performance, the first porous layer is preferably formed of a water-repellent material with low surface free energy, particularly a resin containing fluorine. Examples of resins containing fluorine include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxyfluororesin (PFA), and polyvinylidene fluoride (PVDF). Examples include fluorinated ethylene/hexafluorinated propylene copolymer (FEP), ethylene/tetrafluoroethylene copolymer (ETFE), and ethylene/chlorotrifluoroethylene copolymer (ECTFE). These resins can be used alone or in combination of two or more, if necessary. In this case, a plurality of membranes may be laminated in the first porous layer.

When a water-repellent material is used, it has little effect of sucking up liquid due to capillary force, so it may take some time to suck up the liquid when it comes into contact with an ink image for the first time. For this reason, it is preferable to impregnate the first porous layer with a liquid having a contact angle of less than 90° with the first porous layer before contacting the ink image. This liquid can be applied to the first surface 10a to penetrate into the first porous layer. The liquid to be impregnated into the first porous layer may be prepared by mixing water with a surfactant or a liquid having a low contact angle with the first porous layer.
The thickness of the first porous layer is preferably 50 μm or less, more preferably 30 μm or less. The film thickness of the first porous layer can be obtained, for example, by measuring the film thickness at ten arbitrary points using a linear micrometer OMV_25 (manufactured by Mitutoyo) and calculating the average value.

The first porous layer can be formed by a known thin porous membrane manufacturing method. For example, the first porous layer can be obtained by forming a sheet-like material made of a resin material by extrusion molding or the like and stretching it to a predetermined thickness. Alternatively, the first porous layer may be formed by adding a plasticizer such as paraffin during extrusion molding and removing the plasticizer by heating or the like during stretching. The pore diameter of the first porous layer can be adjusted by appropriately adjusting the amount of plasticizer added, the stretching ratio, etc.

<Second porous layer>
Preferably, the second porous layer has air permeability. The second porous layer may be made of a nonwoven fabric made of resin fibers or a woven fabric. The material of the second porous layer is not particularly limited. However, the second porous layer needs to be configured so that the liquid absorbed by the first porous layer does not flow back. For example, it is preferable that the second porous layer is formed of a material that has a contact angle with respect to the liquid that is equal to or lower than that of the first porous layer.

Examples of materials for the second porous layer include polyolefins (polyethylene (PE), polypropylene (PP), etc.), polyurethane, polyamides such as nylon, polyesters (polyethylene terephthalate (PET), etc.), polysulfone (PSF), etc. Examples include single materials such as, and composite materials thereof. From the viewpoint of air permeability, the average pore diameter of the second porous layer is preferably larger than the average pore diameter of the first porous layer.

<Third porous layer>
The third porous layer is preferably made of nonwoven fabric from the viewpoint of rigidity. As the material for the third porous layer, the same material as that for the second porous layer can be used.
Note that when forming the fourth and subsequent porous layers, the fourth and subsequent porous layers have the same structure as the third porous layer.

<Other materials>
In addition to the porous body 10, the liquid absorbing member 105a may include a reinforcing member that reinforces the side surface of the liquid absorbing member 105a. Alternatively, a belt-like liquid absorbing member 105a may be formed by connecting the ends of the sheet-shaped porous body 10 in the longitudinal direction using a joining member. As a material for the joining member, a non-porous tape material or the like can be used. The bonding member is arranged at a position where it does not come into contact with the ink image, or arranged at such a period that it does not come into contact with the ink image.

<Method for manufacturing liquid absorbing member 105a>
When forming the porous body 10 consisting of N (>2) layers shown in FIG. 2, the porous layers are bonded to each other using a method such as adhesive lamination or thermal lamination. From the viewpoint of air permeability, thermal lamination is preferred. In thermal lamination, for example, a plurality of porous layers are sandwiched and pressed between two heated rollers, and each porous layer is heated.
For example, a portion of each porous layer may be melted and bonded together by heating. Alternatively, the porous layers may be bonded to each other and laminated by interposing a fusing material such as hot melt powder between the porous layers and heating them. The third and subsequent porous layers may be laminated all at once, or may be laminated one layer at a time. The stacking order can be determined as appropriate.

Before laminating the porous layers, the porous layers excluding the porous layer constituting the first surface 10a are inspected to detect the blockage portion 11. If there are many occluded parts 11, the occluded parts 11 may be automatically detected using a digital camera. Heat and pressure are then applied to laminate each porous layer. Next, at least one of the interfaces of each porous layer located closer to the first surface 10a than the blocking part 11 is peeled off by partially peeling the interface in a region facing the blocking part 11. A region 12 is formed. The internal space formed around the peeling region 12 constitutes an internal liquid path. In this internal flow path, the liquid flowing from the first surface 10a toward the closure part 11 flows in the in-plane direction so as to bypass the closure part 11.

<Method for forming peeling region 12>
After laminating a plurality of porous layers by thermal lamination, a peeling region 12 is formed at a desired interface between the porous layers using a peeling liquid. In a porous body in which two porous layers A and B are bonded together, when a stripping liquid is permeated and heat and pressure are applied, the material forming porous layer A or porous layer B, or both, melts due to the heat. and exhibits fluidity. If the wettability of the stripping solution to porous layer A, porous layer B, or both is higher than the wettability of porous layer A and porous layer B when melted, the stripping solution will be applied to porous layer A. , B flows between the layers, causing the adhesive force between these layers to be lost. The peeled region 12 can be formed using this principle.

Specifically, a porous body 10 made of N (>2) layers shown in FIG. 2 is formed. Next, at least one of the interfaces between the respective porous layers from the first porous layer to the i-th porous layer is closed in the direction perpendicular to the first surface 10a of the porous body 10. A stripping liquid is allowed to enter the area facing the portion 11. In this embodiment, a stripping liquid is allowed to enter a region of the interface 10c between the first porous layer and the second porous layer that faces the closed portion 11. Specifically, the stripping liquid is applied from the first surface 10a of the porous body 10, and penetrates into the first porous layer and the second porous layer in order. During this infiltration process, the stripping liquid also infiltrates the region of the interface 10c that faces the closed portion 11. After applying the stripping liquid, heat and pressure are applied to form a stripping region 12 in which the interface 10c is partially peeled off in a region facing the closed portion 11.
The method of applying the stripping liquid is not particularly limited, and any method may be used to apply the stripping liquid as long as the stripping liquid can be infiltrated into the porous body 10. For example, a Rubicel Stick (product name of As One Corporation) may be made to absorb a stripping liquid and brought into contact with the porous body 10. Alternatively, the stripping liquid may be applied without contact using a dropper or syringe. However, if the peeling liquid is peeled off more than necessary, the strength of the liquid absorbing member 105a may decrease, so a method of applying the peeling liquid that allows fine control of the area to which the peeling liquid is applied (or permeation area) is preferable.

It is preferable that at least one of the porous layers (here, the first porous layer and the second porous layer) constituting the interface where the peeling region 12 is formed is made of a resin containing fluorine. Further, the temperature at the time of application of heat and pressure, specifically, the temperature at the interface 10c where the peeling region 12 is formed, is a temperature equal to or higher than the lower melting point of the porous layer forming the interface 10c. It is preferable that Further, it is preferable that the equivalent circle diameter of the peeled region 12 when the porous body 10 is viewed from a direction perpendicular to the first surface 10a is larger than the larger average pore diameter of the porous layer constituting the interface 10c. . This allows the liquid to flow reliably in the in-plane direction. Here, the equivalent circle diameter indicates the diameter of a circle equivalent to the arbitrarily shaped region (a perfect circle having the same area as the arbitrarily shaped region).

Application of the stripping liquid and application of heat and pressure may be performed from the same side of the porous body 10. For example, a stripping liquid may be permeated through the first surface 10a of the porous body 10, and heat and pressure may be applied from the first surface 10a of the porous body 10. Thereby, the peeling region 12 can be precisely formed at the interface between the first porous layer and the second porous layer.

Hereinafter, a method for forming the peeling region 12 will be specifically explained using the three-layer porous body 10 as an example.
FIG. 3 is a schematic diagram for explaining an example of a method of forming a peeling region 12 in a three-layer porous body 10. FIG. 3(a) is a cross-sectional view of the porous body 10 including the closing portion 11. The upper part of FIG. 3(a) shows a projection area 21 in which the closure part 11 is projected in a direction perpendicular to the first surface 10a. FIG. 3(b) is a cross-sectional view showing the permeation region 13 of the stripping liquid that has permeated the porous body 10. The upper part of FIG. 3(b) shows a projected region 22 in which the permeation region 13 is projected in a direction perpendicular to the first surface 10a. FIG. 3(c) is a cross-sectional view showing how the stainless steel probe 14 that applies heat and pressure is brought into contact with the porous body 10. The upper part of FIG. 3(c) shows a projection area 23 in which the contact surface 14a of the probe 14 that contacts the first surface 10a of the porous body 10 is projected in a direction perpendicular to the first surface 10a. ing.

Referring to FIG. 3(a), the porous body 10 is composed of a laminate in which three porous layers 601 to 603 are laminated. Porous layer 601 is the first porous layer that constitutes first surface 10a shown in FIG. Porous layer 602 has closed portions 11 .
First, as shown in FIG. 3(b), a stripping solution is applied from the first surface 10a of the porous body 10 (see arrow A) to form a penetration region 13 of the stripping solution inside the porous body 10. do. The stripping liquid permeation region 13 includes the entire blockage 11 , and the stripping liquid penetrates into a region facing the blockage 11 at the interface between the porous layer 601 and the porous layer 602 . The projection area 22 of the penetration area 13 encompasses the entire projection area 21 of the closure portion 11 .

Next, as shown in FIG. 3(c), the contact surface 14a of the probe 14 is brought into contact with the first surface 10a of the porous body 10, and heat and pressure are applied from the first surface 10a. The projection area 23 of the abutting surface 14a of the probe 14 includes the entire projection area 21 of the occlusion part 11. As a result, heat and pressure are applied to all areas of the interface 10c between the porous layer 601 and the porous layer 602 that face the closed portion 11.
The temperature of the region heated by the probe 14 (specifically, the temperature at the interface 10c) is equal to or higher than the lower melting point of the porous layer 601 and the porous layer 602. When the materials of the porous layers 601 and 602 are melted by heat and exhibit fluidity, the stripping liquid flows between the porous layers 601 and 602, and the adhesive force between the layers is lost. As a result, the interface 10c between the porous layer 601 and the porous layer 602 is partially separated in a region facing the closed portion 11, and a separated region 12 is formed.

In the example of FIG. 3C, the projection area 21 of the closure part 11, the projection area 22 of the penetration area 13, and the projection area 23 of the contact surface 14a of the probe 14 overlap each other. The relationship between the areas of these projection areas 21 to 23 is projection area 22>projection area 23>projection area 21. In this case, the peeling region 12 is formed in a region of the interface 10c between the porous layer 601 and the porous layer 602 that faces the closed portion 11. At the interface 10c, a region where the peeling region 12 is formed corresponds to a region where the projection region 22 of the penetration region 13 and the projection region 23 of the contact surface 14a of the probe 14 overlap. When the porous body 10 is viewed from a direction perpendicular to the first surface 10a, the peeled region 12 overlaps with the entire closed portion 11.
According to the separation region 12 shown in FIG. 3(c), most of the liquid directed from the first surface 10a toward the closure part 11 can be made to flow in the in-plane direction so as to bypass the closure part 11.
Note that the position of the contact surface 14a of the probe 14 with respect to the closed portion 11 may be misaligned. FIG. 4 is a schematic diagram showing a state in which the center of the contact surface 14a of the probe 14 is shifted from the center of the closure part 11. The projection area 22 of the penetration area 13 includes both the projection area 21 of the closure part 11 and the projection area 23 of the contact surface 14a of the probe 14. However, unlike the example in FIG. 3(c), the projection area 23 overlaps a part of the projection area 21. In other words, when the porous body 10 is viewed from a direction perpendicular to the first surface 10a, the peeled region 12 overlaps a part of the closed portion 11. With this structure as well, the liquid flowing from the first surface 10a toward the closure part 11 can be made to flow in the in-plane direction so as to bypass the closure part 11.

In the example of FIG. 3(c), the projection area 23 of the contact surface 14a of the probe 14 is larger than the projection area 21 of the occlusion part 11, but since the size of the occlusion part 11 is not constant, the projection area 21 may be larger than the projection area 23.
FIG. 5 is a schematic diagram showing a state in which the closing portion 11 is larger than the contact surface 14a of the probe 14. The projection area 22 of the penetration area 13 includes both the projection area 21 of the closure part 11 and the projection area 23 of the contact surface 14a of the probe 14, but the projection area 23 is included by the projection area 21. The relationship between the areas of the projection areas 21 to 23 is projection area 22>projection area 21>projection area 23. In this case, when the porous body 10 is viewed from a direction perpendicular to the first surface 10a, the central part of the closed part 11 overlaps with the peeled area 12, but the outer peripheral part of the closed part 11 overlaps with the peeled area 12. do not overlap. With this structure as well, it is possible to cause the liquid heading from the first surface 10a toward the closure part 11 to flow in the in-plane direction so as to bypass the closure part 11. That is, when the porous body 10 is viewed from a direction perpendicular to the first surface 10a, it is preferable that the peeled region 12 overlaps all of the closed portion 11, but even if it overlaps only a portion, the present invention will not be applied. Effects can be obtained.

In all of the above methods, the stripping liquid is applied and the heat and pressure are supplied from the first surface of the porous body 10. A stripping liquid may be applied from one side, and heat and pressure may be applied from the other side. For example, in the example of FIG. 3, the stripping liquid may be applied from the second surface 10b, and the heat and pressure may be applied from the first surface 10a. Conversely, the stripping liquid may be applied from the first surface 10a, and the heat and pressure may be applied from the second surface 10b. However, from the viewpoint of ensuring that the stripping liquid enters the region facing the closing portion 11 at the interface between the porous layers, which is located closer to the first surface 10a than the closing portion 11, the stripping liquid is It is preferable to apply from the surface 10a of the first side.

According to the above method, it is possible to form the peeled region 12 at the interface of any porous layer. For example, in the porous body 10 of FIG. 2, a stripping liquid is applied from the first surface 10a to separate the j-th (2≦j≦i)-th porous layer and the j-1-th porous layer. Penetrate to the interface. Thereafter, heat and pressure are applied from the second surface 10b to partially peel off the interface between the j-th porous layer and the j-1-th porous layer in the region facing the closure part 11. . Thereby, a peeling region 12 can be formed at the interface between the j-th porous layer and the j-1-th porous layer. The heat and pressure applied to the second surface 10b reach a temperature at which the interface between the j-th porous layer and the j-1th porous layer can be peeled off, and the temperature on the first surface 10a side is increased. The temperature at the interface is adjusted so that it does not reach a temperature that would allow peeling.

<Removal liquid>
The stripping liquid may be any material as long as it has high wettability with respect to the material of which the stripping region 12 is to be formed (porous layer, etc.). For example, in the porous body 10 shown in FIG. Composed of PE fiber mass. In this case, a fluorine-based surfactant or fluorine-based oil that easily wets the first porous layer (PTFE) is suitable as the stripping liquid. Examples of the fluorine-based surfactant include Capstone (TM) FS-3100 (trade name of Chemours Corporation). Examples of the fluorine-based oil include DEMNUM S-20 (trade name of Daikin Industries, Ltd.).

<Effects of the blocked part 11 and its solution>
During the manufacturing process of nonwoven fabrics, the fibers that make up the nonwoven fabrics may become unevenly distributed and form fiber clumps. If paper is made as a fiber mass, the fiber density will be high in that part, resulting in a region with low air permeability. In addition, if foreign matter such as dust or abrasion powder gets mixed in, areas with low ventilation may locally occur. For example, when creating a liquid absorbing member by laminating porous materials, foreign matter such as dust and abrasion powder from mechanical equipment can get mixed in between the layers, blocking the pores and locally reducing air permeability. be. These fiber lumps and foreign matter form the closed portion 11 .

Although it depends on the recording process, the liquid absorbing member needs to absorb a large amount of liquid from the ink image in a short time, and if this is not possible, the ink image may be deformed. The performance of the liquid absorbing member is mainly determined by the contact pressure between the ink image and the liquid absorbing member, the flow rate determined by the flow resistance of each layer and the flow resistance of the interface between each layer, and the liquid volume of each layer. If these balances are disrupted, the absorption performance of the liquid absorbing member may deteriorate and the ink image may be deformed. For example, when the contact pressure between the ink image and the liquid absorbing member increases, the liquid absorbing member deforms, resulting in a change in flow resistance and liquid volume. In particular, since the flow resistance increases in the portion where the blockage portion 11 exists, the liquid absorption cannot keep up in that portion, and the ink image is deformed.

In the following, the influence of the closed portion 11 and its solution will be specifically explained using a four-layered porous body as an example.
FIG. 6 is a cross-sectional view of a liquid absorbing member that does not have a closing portion 11 and a peeling region 12. The liquid absorbing member is made of a porous body in which four porous layers 601 to 604 are laminated. A porous layer 601 forms the first surface 10a in contact with the ink image. The liquid is absorbed from the first surface 10a of the porous layer 601 and permeates across the porous layers 601-604 in order. In this liquid absorbing member, since the porous body has uniform air permeability over the entire body, a phenomenon in which the flow of liquid becomes poor in some parts does not occur. Therefore, when the liquid absorbing member is brought into contact with the ink image, the ink image will not be deformed.

FIG. 7 is a cross-sectional view of a liquid absorbing member in which a closing portion 11 is present in a porous body. Porous layers 601-604 are the same as those shown in FIG. Porous layer 602 has closed portions 11 . The liquid is absorbed from the first surface 10a of the porous layer 601 and permeates in the Z direction across the porous layers 601 to 604 in order, but the blocking portion 11 blocks the flow of the liquid. Therefore, the portion of the liquid absorbing member where the closing portion 11 is present cannot sufficiently absorb liquid from the ink image, and as a result, the ink image is deformed. In some cases, the coloring material transfers to the liquid absorbing member. The larger the closed portion 11 is, the larger the deformed part of the ink image becomes, and the higher the visibility of the defective part of the image becomes. On the other hand, the smaller the closed portion 11 is, the smaller the deformed part of the ink image becomes, and the visibility of the defective part of the image becomes lower. For the closed portion 11 that is large enough to cause visual recognition of image defects, measures must be taken so as not to impede the flow of the liquid.

FIG. 8 is a diagram showing an example of a liquid absorbing member having a closing portion 11 and a peeling region 12. Porous layers 601-604 are the same as those shown in FIG. Porous layer 602 has closed portions 11 . The peeling region 12 is provided in a region facing the closed portion 11 at the interface between the porous layer 601 and the porous layer 602. When the porous body is viewed from a direction perpendicular to the first surface 10a, the peeled region 12 overlaps the entire closed portion 11. This structure can be manufactured using the formation method shown in FIG. 3, for example.
Even if a closed portion 11 with low air permeability exists in the porous body, the liquid flowing from the first surface 10a toward the closed portion 11 flows in the in-plane direction of the interface in the peeling region 12, and closes the closed portion 11. It flows in a detour. Therefore, the liquid can be sufficiently absorbed from the ink image even in the portion of the liquid absorbing member where the closing portion 11 is present, as in other portions. Thereby, deformation of the ink image can be suppressed.

FIG. 9 is a diagram showing another example of a liquid absorbing member having a closing portion 11 and a peeling region 12. Porous layers 601-604 are the same as those shown in FIG. Porous layer 602 has closed portions 11 . The peeling region 12 is provided in a region facing the closed portion 11 at the interface between the porous layer 601 and the porous layer 602. When the porous body is viewed from a direction perpendicular to the first surface 10a, the peeled region 12 overlaps a part of the closed portion 11. This structure can be manufactured using the formation method shown in FIG. 4, for example.

Part of the flow of the liquid flowing from the first surface 10a toward the closure part 11 is blocked by the closure part 11, but the remaining part flows in the in-plane direction of the interface in the separation region 12, and flows through the closure part 11. It flows in a detour. Therefore, in the portion of the liquid absorbing member where the closing portion 11 is present, the peeling region 12 can sufficiently absorb liquid from the ink image in the same manner as other portions. Therefore, deformation of the ink image can be suppressed, and the area where defects occur in the image can be made smaller compared to the structure of FIG.

FIG. 10 is a schematic diagram showing yet another example of a liquid absorbing member having a closing portion 11 and a peeling region 12. Porous layers 601-604 are the same as those shown in FIG. Porous layer 603 has closed portions 11 . The peeling region 12 is provided in a region facing the closed portion 11 at the interface between the porous layer 601 and the porous layer 602. Similar to the structure of FIG. 8, when the porous body is viewed from the direction perpendicular to the first surface, the peeled region 12 overlaps the entire closed portion 11. This structure can be manufactured using the formation method shown in FIG. 3, for example.
In the structure of FIG. 10 as well, like the structure of FIG. 8, the liquid flowing from the first surface 10a toward the closing portion 11 flows around the closing portion 11, so that deformation of the ink image can be suppressed.

Note that, from the viewpoint of causing the liquid to flow so as to bypass the closure part 11, it is preferable that the separation region 12 is provided at the interface closest to the closure part 11. For example, in the structure of FIG. 10, the peeling region 12 may be provided in a region of the interface between the porous layer 602 and the porous layer 603 that faces the closed portion 11. By providing the peeling region 12 at the interface closest to the closure part 11, the liquid can be effectively caused to flow around the closure part 11, and as a result, deformation of the ink image can be further suppressed.
On the other hand, the influence of the closed portion 11 on the ink image is greatest on the first surface 10a side, and decreases as the distance from the first surface 10a increases. When the speed in the recording process (rotational speed of the transfer body 101) is high and the contact time between the ink image and the liquid absorbing member is short, it is preferable that the peeling region 12 be formed at an interface close to the first surface 10a side. From this point of view, when the rotational speed of the transfer body 101 is high, the structure shown in FIG. 10 is suitable.
Further, in the example of FIG. 10, the peeling region 12 may be provided at both the interface between the porous layer 601 and the porous layer 602 and the interface between the porous layer 602 and the porous layer 603. This structure also allows the liquid to flow so as to effectively bypass the closing portion 11.

Note that since an ink image is formed on the transfer body 101 by applying the reaction liquid and then ink, the reaction liquid remains in the non-image area where the ink image is not formed without reacting with the ink. There is. The liquid absorbing member 105a absorbs not only the ink image but also the unreacted reaction liquid. In this way, liquid removal by the liquid absorbing member 105a is not limited to liquid component removal from an ink image. Note that the liquid component to be absorbed by the liquid absorbing member 105a is not particularly limited as long as it does not have a fixed shape, has fluidity, and has a substantially constant volume. Examples of liquid components include water, organic solvents, and the like contained in ink and reaction liquid.

Next, the operation and various conditions of the liquid absorption device 105 will be described in detail.
<Pretreatment>
Before bringing the liquid absorbing member 105a into contact with the ink image, it is preferable to perform a pretreatment of applying a treatment liquid to the liquid absorbing member 105a. 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 water-soluble organic solvent is not particularly limited. As the water-soluble organic solvent, known organic solvents such as ethanol and isopropyl alcohol may be used. In the pretreatment of the liquid absorbing member 105a, the method of applying the treatment liquid is not particularly limited. For example, the treatment liquid may be applied using immersion or droplet dropping.

<Pressure conditions>
If the contact pressure between the liquid absorbing member 105a and the ink image on the transfer body 101 is 0.2 MPa or more, the liquid component in the ink image can be separated into solid and liquid in a shorter time, and the liquid component can be removed from the ink image. Therefore, it is preferable. Here, the contact pressure refers to the nip pressure between the transfer body 101 and the liquid absorbing member 105a. For example, the surface pressure is measured using a surface pressure distribution measuring device ("I-SCAN", manufactured by Nitta Co., Ltd.), and the value obtained by dividing the load in the pressurized region by the area is taken as the contact pressure.

<Action time>
The action time (contact time) for bringing the liquid absorbing member 105a into contact with the ink image is preferably within 50 ms. Thereby, it is possible to suppress the coloring material in the ink image from adhering to the liquid absorbing member 105a. Note that the action time can be calculated as a value obtained by dividing the pressure sensing width in the moving direction of the transfer body 101 by the moving speed of the transfer body 101 in the above-mentioned surface pressure measurement. This action time is sometimes called liquid absorption nip time.
In this way, the liquid component is absorbed on the transfer body 101, and an ink image with a reduced amount of liquid component is formed. The ink image after this liquid is removed is transferred onto the recording medium 108.

<Control system>
Next, a control system for the transfer type inkjet recording apparatus will be explained. FIG. 11 is a block diagram showing the configuration of the control system. Referring to FIG. 11, the control system includes a print data generation section 301, an operation control section 302, a printer control section 303, a print medium conveyance control section 304, and an inkjet device 305. The recording data generation unit 301 is an external print server or the like. The operation control unit 302 is an operation panel or the like. The printer control unit 303 implements the recording process. A recording medium conveyance control unit 304 conveys the recording medium. Inkjet device 305 performs printing.

FIG. 12 is a block diagram showing the configuration of the printer control unit 303. Referring to FIG. 12, the printer control unit 303 includes a CPU 401 that controls the entire printer. The CPU 401 is connected to a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, and an ASIC (Application Specific Integrated Circuit) 404 via an internal bus. ROM402 stores a control program for CPU401. RAM 403 is a memory for executing programs. The ASIC 404 is an integrated circuit for specific applications that includes a network controller, a serial IF controller, a head data generation controller, a motor controller, and the like.

The ASIC 404 is connected to the operation control section 302, the printer control section 303, and the recording medium conveyance control section 304. The ASIC 404 is further connected to a liquid absorbing member conveyance control section 405, a transfer body drive control section 407, and a head control section 409. The liquid absorbing member transport control unit 405 drives the liquid absorbing member transport motor 406 and is controlled by commands from the ASIC 404 via the serial IF. The transfer body drive control unit 407 drives the transfer body drive motor 408 and is controlled by commands from the ASIC 404 via the serial IF. The head control unit 409 generates final ejection data, drive voltage, etc. for the inkjet device 305.

Next, a direct writing type inkjet recording apparatus will be explained.
<Direct drawing type inkjet recording device>
FIG. 13 is a schematic diagram showing an example of a schematic configuration of a direct writing inkjet recording apparatus. This inkjet recording apparatus 200 is similar to the above-described transfer type inkjet recording apparatus, except that it does not have a transfer body 101, a support member 102, and a transfer body cleaning member 109, and forms an image on a recording medium 208. be.

The inkjet recording apparatus 200 includes a reaction liquid application device 203 , an ink application device 204 , a liquid absorption device 205 , and a recording medium transport device 207 . The reaction liquid applying device 203 applies a reaction liquid to the recording medium 208 . The ink applying device 204 applies ink to the recording medium 208. The liquid absorbing device 205 brings the liquid absorbing member 205a into contact with the ink image on the recording medium 208 to absorb liquid components contained in the ink image. These reaction liquid applying device 203, ink applying device 204, and liquid absorbing device 205 have the same configuration as described in the above-mentioned transfer type inkjet recording device, so a detailed description of their configuration will be omitted here. do.

The reaction liquid application device 203 includes a reaction liquid storage section 203a and reaction liquid application members 203b and 203c. The reaction liquid storage section 203a and the reaction liquid application members 203b and 203c are the same as those described in the transfer type inkjet recording apparatus.
The liquid absorbing device 205 includes a liquid absorbing member 205a and a pressing member 205b that presses the liquid absorbing member 205a against the ink image on the recording medium 208. There are no particular restrictions on the shapes of the liquid absorbing member 205a and the pressing member 205b, and shapes similar to those described for the transfer type inkjet recording apparatus can be used. The liquid absorption device 205 may include a tension member that stretches the liquid absorption member 205a. A plurality of tension rollers 205c, 205d, 205e, 205f, and 205g are provided as tension members. Note that the number of tension rollers is not limited to five, and may be arranged as required depending on the device design.

The ink applying device 204 and the liquid absorbing device 205 are arranged to face the surface of the recording medium 208 on which the ink image is formed. A recording medium support member (not shown) that supports the recording medium 2008 from below may be provided at a position facing each of the ink applying device 204 and the liquid absorbing device 205 with the recording medium 208 interposed therebetween.
The recording medium conveying device 207 includes a recording medium feeding roller 207a, a recording medium winding roller 207b, and recording medium conveying rollers 207c, 207d, 207e, and 207f. The recording medium 208 fed out from the recording medium feeding roller 207a is conveyed by the recording medium conveying rollers 207c, 207d, 207e, and 207f, and is wound up by the recording medium winding roller 207b. The recording medium conveying device 207 is not limited to the configuration shown in FIG. 13, and a conveying means of a known direct drawing inkjet recording device may be applied.

<Control system>
The control system of the direct writing inkjet recording apparatus has the same configuration as the control system shown in FIG. has.
FIG. 14 is a block diagram showing the configuration of the printer control unit 303. This printer control unit 303 has the same configuration as that shown in FIG. 12 except that it does not include a transfer body drive control unit 407 and a transfer body drive motor 408.
The printer control unit 303 shown in FIG. 14 includes a CPU 501, a ROM 502, a RAM 503, an ASIC 504, a liquid absorbing member transport control unit 505, a liquid absorbing member transport motor 506, and a head control unit 509. These are the same as those shown in FIG. 12 and perform similar operations.

Next, an example of a transfer-type inkjet recording device to which the method of manufacturing a liquid-absorbing member of the present invention is applied will be described, and a transfer-type inkjet recording device equipped with an existing liquid-absorbing member will be cited as a comparative example. The comparison results will be explained. In the following description, "parts" are based on mass unless otherwise specified.

(Example 1)
In this example, the transfer type inkjet recording apparatus shown in FIG. 1 was used. As the elastic layer of the transfer body 101, a sheet obtained by coating a 0.5 mm thick PET sheet with silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE12) to a 0.3 mm thickness was used. A heat insulating layer made of foamable silicone rubber containing air bubbles and having a thickness of 0.5 mm was provided below the elastic layer. The elastic layer was fixed to the heat insulating layer using double-sided tape.

In addition, a mixture of a condensate obtained by mixing glycidoxypropyltriethoxysilane and methyltriethoxysilane at a molar ratio of 1:1 and heating under reflux and a photocationic polymerization initiator (manufactured by ADEKA, product name: SP150) was prepared. Created. Atmospheric pressure plasma treatment was performed so that the contact angle of water on the surface of the elastic layer was 10 degrees or less, and the mixture was applied onto the elastic layer. Then, a film was formed by UV irradiation (high-pressure mercury lamp, cumulative exposure amount 5000 mJ/cm ² ) and thermosetting (150° C. for 2 hours) to form a surface layer with a thickness of 0.5 μm on the elastic layer.
The transfer body 101 formed as described above was fixed to the support member 102 using double-sided tape.

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

<Preparation of resin particles>
A four-necked flask equipped with a stirrer, a reflux condenser, and a nitrogen gas inlet tube was prepared. Into this flask were placed 18.0 parts of butyl methacrylate, 2.0 parts of a polymerization initiator (2,2'-azobis(2-methylbutyronitrile)), and 2.0 parts of n-hexadecane, and nitrogen was added to the reaction system. Gas was introduced and stirred for 0.5 hour. Furthermore, 78.0 parts of a 6.0% aqueous solution of an emulsifier (trade name: NIKKOL BC15, manufactured by Nikko Chemicals) was added dropwise to the flask and stirred for 0.5 hour. Next, the mixture was emulsified by irradiating it with ultrasonic waves for 3 hours using an ultrasonic irradiator. Thereafter, a polymerization reaction was carried out at 80° C. for 4 hours under a nitrogen atmosphere. After cooling the reaction system to 25°C, the components were filtered and an appropriate amount of pure water was added to prepare an aqueous dispersion of resin particles 1 with a content of resin particles 1 (solid content) of 20.0%. did.

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

<Preparation of pigment dispersion>
10.0 parts of pigment (carbon black), 15.0 parts of an aqueous solution of Resin 1, and 75.0 parts of pure water were mixed. This mixture and 200 parts of zirconia beads with a diameter of 0.3 mm were placed in a batch type vertical sand mill (manufactured by Imex) and dispersed for 5 hours while cooling with water. Thereafter, coarse particles were removed by centrifugation, and filtered under pressure using a cellulose acetate filter (manufactured by Advantech) with a pore size of 3.0 μm. A pigment dispersion K having a content of 3.0% was prepared.

<Preparation of ink>
Each component shown below was mixed and thoroughly stirred, followed by pressure filtration using a cellulose acetate filter (manufactured by Advantech) with a pore size of 3.0 μm to prepare each ink. Acetylenol E100 is a surfactant manufactured by Kawaken Fine Chemicals.

<Ink composition>
・Pigment dispersion liquid K: 20.0% by mass
・Aqueous dispersion of resin particles 1: 50.0% by mass
・Aqueous solution of resin 1: 5.0% by mass
・Glycerin: 5.0% by mass
・Diethylene glycol: 7.0% by mass
・Acetylenol E100: 0.5% by mass
・Pure: 12.5% by mass

As the ink application device 104, an inkjet device having an inkjet head of a type that discharges ink on demand using an electrothermal conversion element was used. The amount of ink applied was 20 g/m ² .

<Liquid absorption member>
As the liquid absorbing member 105a, a three-layer porous body manufactured by the procedure shown in FIGS. 3(a) to 3(c) was used. For the porous layer 601 on the side that contacts the ink image, porous PTFE with an average pore diameter of 0.3 μm was used. For the porous layer 602, a porous membrane made of fibers made of polypropylene (PP) coated with polyethylene (PE) was used. As the porous layer 603, a porous membrane made of polyphenyl sulfide was used. In the porous layer 602, the fibers constituting the pores formed a mass, creating a region (occluded portion 11) that closed the pores of the porous layer. The occluded portion 11 was visually distinguishable. Image analysis was performed on the area of the occluded portion 11 using a microscope (VHX-5000 (trade name), manufactured by Keyence Corporation). As a result of image analysis, the closed portion 11 was a site where the fibers were solidified, and the gap necessary for liquid permeation had disappeared. Further, the area of the projected region of the closed portion 11 projected in the direction perpendicular to the surface of the liquid absorbing member 105a was approximately 2 mm ² .

Capstone (TM) FS-3100 (manufactured by Chemours Co., Ltd.), which is a fluorosurfactant, was used as a stripping liquid. A stripping solution was applied to the porous layer 601 using Rubicel Stick (product name of As One Corporation). At this time, it was visually confirmed that the permeation region 13 of the stripping liquid had expanded greatly to include the closed portion 11 and that the projected region 22 of the permeated region 13 included the projected region 21 of the closed portion 11 . The contact surface 14a of the probe 14 heated to 145° C. was pressed against the first surface 10a for 60 seconds to form a peeling region 12 in the region facing the closed portion 11 at the interface between the porous layer 601 and the porous layer 602. .
The liquid absorbing member in which the peeling region 12 was formed was immersed in a treatment liquid consisting of 95 parts of ethanol and 5 parts of water, and after the liquid was allowed to permeate, the liquid was replaced with a liquid consisting of 100 parts of water, and then used for liquid removal. Through this liquid replacement step, the stripping solution in the permeation region 13 was washed away, and an internal space was formed around the stripping region 12. As the pressing member 105b, a roller having a diameter of 200 mm was used.
The transport speed of the liquid absorbing member 105a was adjusted to be equal to the moving speed of the transfer body 101. Aurora coated paper (trade name, manufactured by Nippon Paper Industries Co., Ltd., basis weight 104 g/m ² ) was used as the recording medium 108. The conveyance speed of the recording medium 108 was 0.6 m/s.

The liquid component was absorbed from the ink image on the transfer body 101 using the liquid absorbing member 105a of this example. The liquid was able to be absorbed from the ink image even in the portion including the closed portion 11, and an image was obtained at a level that could not be recognized as an image defect.

(Example 2)
The basic configuration and operation of this embodiment are the same as those of the first embodiment. However, unlike Example 1, in this example, the peeled region 12 was formed as shown in FIG. Specifically, the following process was performed to provide a peeled region on the closed portion 11 existing in the porous layer 602 of the liquid absorbing member 105a.
(1) Detection of blockage 11 (2) Application of stripping liquid to blockage 11 (3) Application of heat and pressure

The process of "detection of the closed portion 11" was performed visually. If there are many occluded parts 11, the occluded parts 11 may be automatically detected using a digital camera.
In the process of "applying stripping liquid to the closed portion 11", Capstone (TM) FS-3100 (manufactured by Chemours Co., Ltd.) was used as the stripping liquid. A stripping solution was applied to the porous layer 601 using Rubicel Stick (product name of As One Corporation). The stripping liquid permeated from the porous layer 601 to the porous layer 602. The region to which the stripping solution is applied by the Rubicel stick is the penetration region 13 of the stripping solution. The area of the projected region 21 of the closed portion 11 was 2 mm ² , and the amount of the stripping liquid applied calculated from the weight change was about 100 ng.

In the "application of heat and pressure" process, the contact surface 14a of the probe 14 heated to 145° C. is pressed against the first surface 10a for 60 seconds, and the closed portion 11 at the interface between the porous layer 601 and the porous layer 602 is A peeling region 12 was formed in a region facing the. The projection area 23 of the contact surface 14a of the probe 14 overlaps a part (70% area) of the projection area 21 of the occlusion part 11. As a result, a liquid absorbing member 105a having a structure in which the peeling region 12 overlaps a part of the closing portion 11 as shown in FIG. 9 was manufactured.
The liquid component was absorbed from the ink image on the transfer body 101 using the liquid absorbing member 105a of this example. Although some deformation of the ink image occurred in the portion including the closed portion 11, the amount of deformation was small and within an allowable range.

(Example 3)
The basic configuration and operation of this embodiment are the same as those of the first embodiment. However, unlike Example 1, in this example, the peeled region 12 was formed as shown in FIG. In this embodiment, the projection area 23 of the abutting surface 14a of the probe 14 is smaller than the projection area 21 of the occlusion part 11. For this reason, at the interface between the porous layers, it was not possible to peel off the entire region facing the closed portion 11, but only the central portion could be peeled off.
The liquid component was absorbed from the ink image on the transfer body 101 using the liquid absorbing member 105a of this example. Although some change in the ink image was observed in the portion that was not peeled off, including the closed portion 11, the amount of deformation was small and within an acceptable range.

(Comparative example 1)
The basic configuration and operation of this comparative example are the same as those of the first embodiment. Absorbent members were produced by visually selecting those having a closed portion having an area comparable to that of Example 1, and applying heat and pressure in the same manner as in Example 1. However, in this comparative example, polyethylene glycol was used as the stripping liquid. As a result, the adhesive force between the porous layers was not lost, and the peeling region 12 could not be formed in the region facing the closed portion 11 at the interface between the porous layers.
The liquid component of the ink image on the transfer body 101 was absorbed using the liquid absorbing member of this comparative example. In the portion including the blockage part 11, the ink image was significantly deformed because no liquid flow bypassed the blockage part 11. It was confirmed that this amount of deformation was at an unacceptable level and caused image defects.

(Comparative example 2)
The basic configuration and operation of this comparative example are the same as those of the first embodiment. However, in this comparative example, the heating temperature of the probe when producing the liquid absorbing member was 100°C. For this reason, when applying heat and pressure, it is not possible to apply a sufficient amount of heat to the liquid absorbing member, and as a result, the adhesive force between the porous layers is not lost, and the adhesive force between the porous layers is not lost. It was not possible to form the peeling area 12 in the area where the peeling area 12 was removed.
The liquid component of the ink image on the transfer body 101 was absorbed using the liquid absorbing member of this comparative example. As in Comparative Example 1, the ink image was significantly deformed because no liquid flow that bypassed the closing portion 11 occurred in the portion including the closing portion 11. It was confirmed that this amount of deformation was at an unacceptable level and caused image defects.

10 Porous body 10a First surface 11 Closure part 12 Peeling region 105a Liquid absorbing member

Claims (12)

The porous body has a plurality of porous layers laminated together, the porous body has a first surface that absorbs liquid, and the porous body absorbs liquid in a first direction that crosses each porous layer from the first surface. A method for manufacturing a liquid absorbing member in which the liquid permeates,
The number of layers of the porous layer is N (>2), the porous layer constituting the first surface is the first porous layer, and the i-th (2≦i≦N)-th porous layer. forming the porous body including a closing portion that blocks the flow of liquid in the first direction;
A stripping liquid is applied to the porous body, and at least one of the interfaces between each porous layer from the first porous layer to the i-th porous layer is opposed to the closed part of the interface. A method for manufacturing a liquid absorbing member, comprising the steps of: infiltrating the stripping liquid into a region where the stripping liquid is applied, and applying heat and pressure to form a stripping region in which the interface is partially stripped in the region. . 2. The method of manufacturing a liquid absorbing member according to claim 1, wherein the application of the stripping liquid and the application of the heat and pressure are performed from the same surface of the porous body. The liquid absorber according to claim 2, wherein the stripping liquid is applied from the first surface of the porous body, and the heat and pressure are applied from the first surface of the porous body. Method of manufacturing parts. 4. The method for manufacturing a liquid absorbing member according to claim 3, wherein the peeling region is formed at an interface between the first porous layer and the second porous layer. The liquid according to claim 1, characterized in that the stripping liquid is applied from one side to two mutually opposing sides of the porous body, and the heat and pressure are applied from the other side. Method for manufacturing an absorbent member. The stripping liquid is applied from the first surface of the porous body, and the heat and pressure are applied from a second surface of the porous body opposite to the first surface. The method for manufacturing a liquid absorbing member according to claim 5. Any one of claims 1 to 6, wherein the peeled region overlaps at least a portion of the closed portion when the porous body is viewed from a direction perpendicular to the first surface. 1. A method for manufacturing a liquid absorbing member according to item 1. Any one of claims 1 to 6, characterized in that, when the porous body is viewed from a direction perpendicular to the first surface, the peeled region overlaps the entirety of the closed portion. A method for manufacturing a liquid absorbing member according to. 9. The method for manufacturing a liquid absorbing member according to claim 1, wherein at least one of the porous layers constituting the interface where the peeling region is formed is made of a fluorine-containing resin. 10. The method for manufacturing a liquid absorbing member according to claim 9, wherein the stripping liquid is a fluorine-based surfactant or a fluorine-based oil. The temperature at the interface where the peeled region is formed when the heat and pressure are applied is a temperature equal to or higher than the lower melting point of the two porous layers forming the interface. A method for manufacturing a liquid absorbing member according to any one of claims 1 to 10. The porous body has a plurality of porous layers laminated together, the porous body has a first surface that absorbs liquid, and the porous body absorbs liquid in a first direction that crosses each porous layer from the first surface. A method for manufacturing a liquid absorbing member in which the liquid permeates,
inspecting the porous layers other than the porous layer constituting the first surface to detect a blockage that blocks the flow of liquid in the first direction;
applying heat and pressure to laminate the plurality of porous layers;
Among the interfaces of each of the porous layers, at least one of the interfaces located closer to the first surface than the closure part is partially peeled off in a region facing the closure part to form an internal layer. A method of manufacturing a liquid absorbing member, the method comprising: forming a liquid path.

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