JP2021037620A - Method for manufacturing porous body for an inkjet recording device - Google Patents

Abstract

To provide a method for producing a porous body for an inkjet recording device capable of suppressing image flow and enhancing the adhesiveness of laminated porous layers.SOLUTION: A method for producing a porous body which adjusts a heating temperature in a heat treatment process to a specific range and perform a specific surface treatment in a surface treatment process, wherein the method for producing a porous body for an inkjet recording device comprises of steps of a the heat treatment process of forming a laminate by heating in a state where a first porous layer having a first resin and a second porous layer having a second resin are overlapped with each other, the surface treatment process that applies surface treatment on a surface of the first porous layer and a surface of the second porous layer on a side where the first porous layer and the second porous layer are in contact with each other in the laminate.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a porous body for an inkjet recording device.

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

Therefore, in order to remove the liquid component in the ink, a method of drying the recording medium by means such as warm air or infrared rays, or a method of drying the liquid component contained in the ink image formed on the transfer body by thermal energy or the like. A method of transferring an ink image to a recording medium such as paper after drying is known.

Further, as a means for removing the liquid component, Patent Document 1 proposes a method of absorbing and removing the liquid component from the ink image by using a porous body instead of thermal energy such as infrared rays and bringing it into contact with the ink image. Has been done.

However, the porous body used for removing the liquid has a liquid absorbency that absorbs the liquid component from the ink image and a filtering property that absorbs the liquid component without passing the solid content such as a pigment contained in the ink image. Further improvement is required in order to achieve both at a high level.

In the field of air filter filter media used for removing dust, a configuration in which a filtering layer having a small pore diameter and high flow resistance is thinned and a breathable support material is laminated is known as a method for achieving both air permeability and filtering property. There is. However, there is a problem that the adhesiveness between the filtering layer and the breathable support tends to be insufficient, and the filtering layer is easily peeled off during processing or use of the filter filter medium.

In response to this problem, in Patent Document 2, two layers of breathable heat-sealing members having different heat softening points are arranged between the polytetrafluoroethylene membrane and the breathable support material, and heat treatment is performed. , A method of improving adhesiveness without impairing air permeability has been proposed.

Further, Patent Document 3 proposes a method of applying plasma treatment as a treatment for forming a film on the surface of a non-woven fabric to improve the adhesiveness between the non-woven fabric and the film.

Japanese Unexamined Patent Publication No. 2005-161610 Japanese Unexamined Patent Publication No. 2006-150275 Japanese Unexamined Patent Publication No. 2003-13357

However, according to the study by the present inventors, when a laminated porous body in which a film-like porous body is laminated by heat laminating or adhesive laminating is used as the porous body described in Patent Document 1, the material at the time of laminating is used. The holes were sometimes blocked due to melting or adhesion of adhesive. If the vacancies are blocked, the liquid absorbency will decrease. Due to this decrease in liquid absorbency, the liquid component cannot be sufficiently absorbed within the contact time between the porous body and the ink image, and the liquid component in the ink image moves to the rear end side with respect to the moving direction of the ink image. It was found that "image flow", which is swept away, is likely to occur.

Further, in the filter filter medium described in Patent Document 2, since the fiber diameter of the blended fibers constituting the breathable support is large, the area of the adhesion point with the filtering layer is large, and the breathability may be lowered. Do you get it. Further, it was found that since the fiber diameter is large, the distance between the adhesive points becomes wide and the filtering layer may be peeled off from the breathable support.

Further, in the method of applying plasma treatment to the surface of the non-woven fabric described in Patent Document 3, although the adhesiveness between the surface of the porous film and the film is high, the adhesive area between the fibers constituting the porous film is small, so that the fibers are bonded to each other. It was found that the adhesiveness of the material was insufficient.

Therefore, an object of the present invention is to provide a method for producing a porous body for an inkjet recording device, which can suppress image flow and enhance the adhesiveness of laminated porous layers.

The above object is achieved by the following invention. That is, the method for producing a porous body for an inkjet recording apparatus according to the present invention is a state in which a first porous layer having a first resin and a second porous layer having a second resin are superposed. In the heat treatment step of forming a laminate by heating with, and the first porous layer on the side where the first porous layer and the second porous layer in the laminate are in contact with each other. A method for producing a porous body for an inkjet recording apparatus, which comprises a surface treatment step of applying a surface treatment to the surface and the surface of the second porous layer, wherein the first resin and the second resin are used. Of these, a resin having the lowest melting point (Tm) or glass transition point (Tg) as compared with the melting point (Tm) in the case of a crystalline resin and the glass transition point (Tg) in the case of a non-crystalline resin. When the resin (A) is used as the resin (A), the heating temperature in the heat treatment step is Tm or more and Tm + 30 ° C. or less when the resin (A) is a crystalline resin, and the resin (A) is a non-crystalline resin. In the case of Tg or more and Tg + 30 ° C. or less, the surface treatment step is performed on the side where the first porous layer and the second porous layer in the laminate are not in contact with each other. It is a step of performing a surface treatment of either plasma treatment or corona treatment from the surface of the quality layer or the surface of the second porous layer.

According to the present invention, it is possible to provide a method for producing a porous body for an inkjet recording device, which can suppress image flow and enhance the adhesiveness of laminated porous layers.

It is a schematic diagram which shows an example of the structure of the electrospinning apparatus used in a fiber forming process. It is a schematic diagram which shows an example of the structure of the transfer type inkjet recording apparatus. It is a schematic diagram which shows an example of the structure of the direct drawing type inkjet recording apparatus.

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

The method for producing a porous body for an inkjet recording device of the present invention includes the following steps (i) and (ii).
(I) A heat treatment step of forming a laminate by heating a first porous layer having a first resin and a second porous layer having a second resin in a superposed state.
(Ii) The surface of the first porous layer and the surface of the second porous layer on the side where the first porous layer and the second porous layer are in contact with each other in the laminate. A surface treatment process that applies surface treatment to the material.

Each step in the production method of the present invention will be described below.

<Heat treatment process>
In the heat treatment step, the first porous layer having the first resin and the second porous layer having the second resin are superposed and heated to form a laminate.

The heating temperature in this heat treatment step is adjusted as follows.

Of the first resin and the second resin, the lowest Tm or Tg is compared at the melting point (Tm) when it is a crystalline resin and at the glass transition point (Tg) when it is a non-crystalline resin. The resin to have is referred to as resin (A). The heating temperature is Tm or more and Tm + 30 ° C. or less when the resin (A) is a crystalline resin, and Tg or more and Tg + 30 ° C. or less when the resin (A) is a non-crystalline resin. is important.

When the heating temperature is less than Tm when the resin (A) is a crystalline resin and less than Tg when the resin (A) is a non-crystalline resin, the resin (A) does not soften and is first porous. The quality layer and the second porous layer are not adhered to each other, and it becomes difficult to improve the adhesiveness between the first porous layer and the second porous layer. On the other hand, when the heating temperature exceeds Tm + 30 ° C. when the resin (A) is a crystalline resin and exceeds Tg + 30 ° C. when the resin (A) is a non-crystalline resin, the resin melts. It's going too far. Then, the molten resin clogs the pores (voids) of the first porous layer and the second porous layer, so that the absorption of the liquid component of the porous body becomes insufficient and image flow occurs. It will be easier to do. On the other hand, in the present invention, when the resin (A) is a crystalline resin, the temperature is Tm or more and Tm + 30 ° C. or less, and when the resin (A) is a non-crystalline resin, the temperature is Tg or more and Tg + 30 ° C. or less. It is heated in. Thereby, the adhesiveness between the first porous layer and the second porous layer can be enhanced in a state where the pores of the first porous layer and the second porous layer are not easily clogged.

The heating temperature is preferably Tm or more and Tm + 20 ° C. or less when the resin (A) is a crystalline resin, and Tg or more and Tg + 20 ° C. or less when the resin (A) is a non-crystalline resin.

In the present invention, the crystalline resin refers to a resin having Tg and Tm, and the non-crystalline resin refers to a resin having only Tg without having Tm. The Tg and Tm of the resin can be measured by differential scanning calorimetry (DSC) defined by JIS K7121.

In addition, in order to increase the number of bonding points between the first porous layer and the second porous layer and further enhance the adhesiveness between the first porous body and the second porous body, the first porous layer And the second porous layer are preferably heat-treated while being pressurized. That is, the heat treatment step is preferably a heat pressurization treatment step. By pressurizing, the contact area and contact point between the first porous layer and the second porous layer increase, so that the adhesion becomes easier. The pressure in the heating and pressurizing treatment step is preferably at 0.1 kg / cm ² or more 5 kg / cm ² or less, more preferably 0.1 kg / cm ² or more 3 kg / cm ² or less.

As the heating device for performing the heat treatment, a hot air dryer, an oven, an IR heating device, a microwave heating device, or the like can be used. When further pressurizing, a flat plate press with a heating mechanism, a roll press, a laminating device, a calender device, or the like can be appropriately used.

The first resin contained in the first porous layer and the second resin contained in the second porous layer are not particularly limited, but are, for example, polyethylene, polypropylene, polyacrylic nitrile, polycarbonate, and the like. Polyethylene oxide, polyethylene glycol, polyethylene terephthalate, polyethylene naphthalate, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, polymethacrylic acid, polymethylmethacrylate, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, Polyvinyl alcohol, polyvinylpyrrolidone, polyallylate, polyacetal, polystyrene, polysulfone, polyethersulfone, polyphenylsulfone, polyphenylene sulfide, polyamide, polyimide, polyamideimide, aramid, polyimidebenzazole, polybenzoimidazole, nylon, polyurethane, polyglycolic acid , Polylactic acid, fluororesin, cellulose compounds and the like.

As these resins, one kind or two or more kinds may be used as needed, and resins other than these examples can also be used.

Further, the porous body in the present invention absorbs at least a part of the liquid component from the ink image by bringing the ink into contact with the ink image formed by applying the ink to a medium to be ejected such as a recording medium or a transfer medium. It is used for. From the viewpoint of suppressing adhesion of the coloring material when in contact with the ink image and improving the cleanability of the porous body, the first resin contained in the first porous layer in contact with the ink image is fluorine having a low surface free energy. It is preferably a resin.

Examples of the fluororesin include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride (PVF), perfluoroalkoxyfluororesin (PFA), and tetrafluoride. Ethylene-tetrafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), poly (vinylidene fluoride-co-hexafluoropropylene) ) (PVDF-HFP), ethylene tetrafluoride-propylene hexafluoride-vinylidene fluoride copolymer (TFE-HFP-VDF) and the like. Among them, polytetrafluoroethylene (PTFE) is preferable because it can maintain a low surface free energy even immediately after the surface treatment step described later.

<Surface treatment process>
In the surface treatment step, the first porous layer and the second porous layer in the laminate having the first porous layer and the second porous layer heated in the heat treatment step come into contact with each other. Surface treatment is applied to the surfaces of the first and second porous layers on the side of the surface. Then, this surface treatment is performed on the surface of the first porous layer or the second porous layer on the side where the first porous layer and the second porous layer in the laminated body are not in contact with each other. It is carried out by performing plasma treatment and corona treatment from the surface of the layer. By this surface treatment, the adhesiveness between the first porous layer and the second porous layer can be further enhanced. Although the details of the reason why the adhesiveness is improved are unknown, the present inventors chemically change the resin existing on the surfaces of the first porous layer and the second porous layer by plasma treatment or corona treatment. It is speculated that the hydrophilic groups generated in the above contribute to the improvement of adhesiveness. Specifically, it is said that the hydrophilicity of the surface of the porous layer forms a large number of hydrogen bonds between the first porous layer and the second porous layer, so that the adhesiveness is improved. Conceivable.

Further, local heat generation generated during the surface treatment causes local fusion on the surface where the first porous layer and the second porous layer come into contact with each other, which also contributes to the improvement of adhesiveness. It may be.

The surface treatment step is performed on the surface of the first porous layer or the second porous layer on the side where the first porous layer and the second porous layer in the laminate are not in contact with each other. This is a step of performing a surface treatment of either plasma treatment or corona treatment from the surface of the above. Since the first porous layer and the second porous layer have pores (voids), ions, electrons, etc. generated by plasma treatment or corona treatment generated by plasma treatment pass through these pores. The contact portion between the first porous layer and the second porous layer can be reached.

When the surface treatment step is first performed and then the heat treatment step is performed, the adhesiveness between the first porous layer and the second porous layer cannot be sufficiently enhanced. This is because the contact area between the fibers is small and sufficient adhesiveness cannot be obtained only by superimposing the first porous layer and the second porous layer. On the other hand, as in the present invention, by first performing the heat treatment step, the first porous layer and the second porous layer are preliminarily adhered to increase the contact area, and then the surface. By performing the treatment step, the adhesiveness between the first porous layer and the second porous layer can be sufficiently enhanced.

This surface treatment may be performed to such an extent that hydrophilic groups are generated on the surface of the porous layer, and the treatment apparatus and treatment conditions when each treatment method is used can be appropriately selected. Whether or not hydrophilic groups can be generated on the porous surface by the above surface treatment depends on, for example, the presence or absence of detection of hydroxyl groups (-OH), carboxyl groups (-COOH), etc. in the measurement of the infrared absorption spectrum on the surface of the porous layer. You can judge. It can also be determined by the permeation rate when liquids having different surface free energies are dropped on the laminated body subjected to this surface treatment. Further, the contact angle of the water of the resin itself constituting the laminated body is measured, and it can be determined by whether or not the contact angle decreases after this surface treatment. Further, it can be determined by using the plasma indicator PLAZMARK (manufactured by Sakura Color Products Corporation), which is an indicator for confirming the plasma processing effect. This plasma indicator can be used not only for atmospheric pressure plasma processing but also for corona processing.

When performing plasma processing, low-pressure plasma processing, atmospheric pressure plasma processing, etc. are used, but the processing time can be shortened because a vacuum device such as a vacuum container or an exhaust device is not required, and the complicated large shape. Atmospheric pressure plasma treatment is preferable because it is effective for treating the parts of the above. Further, since the atmospheric pressure plasma treatment has a larger amount of raw material gas molecules than the low pressure plasma treatment, it is possible to generate a very high density plasma, and a high speed treatment process can be expected. Examples of the plasma processing apparatus using the atmospheric pressure plasma include the atmospheric pressure plasma surface treatment apparatus AP-T05-S440 (manufactured by Sekisui Chemical Co., Ltd.). There are two types of plasma processing methods, a direct method and a remote method, which can be appropriately selected according to the resin type and the processing time. The amount of discharge discharged between the electrodes when generating plasma is preferably 300 to 1000 W from the viewpoint of generating a sufficient amount of plasma. The plasma processing speed is preferably 1 to 500 mm / sec. The irradiation distance is preferably 0.5 to 10 mm in order to stably secure a distance that does not interfere with the processed article.

Further, as an example of the corona processing apparatus using the corona treatment, for example, the corona surface modification evaluation apparatus TEC-4AX (manufactured by Kasuga Electric Works Ltd.) and the like can be mentioned. The corona processing speed is preferably 1 to 500 mm / sec. The irradiation distance is preferably 0.5 to 10 mm in order to stably secure a distance that does not interfere with the processed article. The amount of corona discharge is preferably 1 to 100 W · min / m ^2.

When the surface of the first porous layer having a fluororesin as the first resin is subjected to surface treatment by plasma treatment or corona treatment, the surface treatment may temporarily make the surface hydrophilic. When the first porous layer is brought into contact with the ink image to absorb the liquid component in the ink image, if the surface of the first porous layer is in a hydrophilic state, it is found in the ink image. Since the coloring material easily adheres to the first porous layer, the image quality may deteriorate. Therefore, when the porous material produced by the production method of the present invention is used in an inkjet recording device, it is necessary to wait for the water repellency of the fluororesin to recover. Whether or not the water repellency is restored can also be determined by the above-mentioned IR spectrum measurement and water contact angle measurement.

Further, when the surface of the porous layer is temporarily hydrophilized by the surface treatment, it is preferable to perform a water repellent treatment on the surface-treated porous layer. As a water repellent treatment method, there is a method of coating a porous layer with a water repellent agent. The water repellent used for this water repellent treatment preferably contains a fluororesin or a silicone resin, and among them, those containing a fluororesin having particularly high water repellency are more preferable.

Examples of the water-repellent treatment method other than the water-repellent agent include a method of exposing to a reactive fluorine gas atmosphere and a fluorine plasma treatment during the above-mentioned plasma treatment. The method of applying the fluorine plasma treatment at the time of the plasma treatment is preferable because the water repellent treatment can be performed at the same time as improving the adhesiveness.

In the surface treatment step, the surface treatment may be performed from the side of the first porous layer and the second porous layer having a low galley value measured by a galley tester specified by JIS P8117. preferable. The lower the galley value, the higher the breathability. Due to the high air permeability of the porous layer, electrons, ions, radicals, etc. generated by plasma treatment or corona treatment can be emitted from the surface side of the first porous layer or the second porous layer to the inside of these porous layers. And easily reach the interface between the first porous layer and the second porous layer. As a result, as described above, the adhesion at the interface between the first porous layer and the second porous layer is strengthened.

Further, it is more preferable that the porous layer gullet value on the side to be surface-treated is 5 seconds or less. If the galley value is 5 seconds or less, the air permeability is higher, and the above electrons, ions, radicals, etc. can reach the interface between the first porous layer and the second porous layer more, and the first This is because the adhesion at the interface between the first porous layer and the second porous layer is further strengthened.

Factors that determine the galley value of the porous layer include fiber diameter, pore diameter, thickness, and porosity. By adjusting these requirements, the galley value can be controlled.

The porous body in the present invention is used to absorb at least a part of a liquid component from an ink image by bringing the ink into contact with an ink image formed by applying the ink to a medium to be ejected such as a recording medium or a transfer medium. It is something that can be done. From the viewpoint of suppressing adhesion of the coloring material when in contact with the ink image, the fiber diameter of the first porous layer in contact with the ink image is preferably 0.05 μm or more and 1 μm or less, and 0.05 μm or more and 0.5 μm or more. The following is more preferable. The pore size of the first porous layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.1 μm or more and 0.6 μm or less. The thickness of the first porous layer is preferably 30 μm or less, more preferably 20 μm or less, still more preferably 10 μm or less. The porosity of the first porous layer is preferably 40% or more, more preferably 60% or more. In the present invention, the fiber diameter was determined by measuring the diameters of 10 fibers that can be clearly identified by the SEM photograph and calculating the average value. The pore size was measured by a pore distribution measuring device, Polymer 3Gz (manufactured by Kantachrome). The thickness of the porous layer was determined by measuring the thickness of any 10 points with a straight-ahead micrometer CLM1-15QM (manufactured by Mitutoyo) and calculating the average value.

A known method such as an electrospinning method or a melt blow method can be used to form the first porous layer. Among them, the electrospinning method capable of forming a porous layer composed of fine fibers is preferable. This is because the smaller the fiber diameter, the better the filtering property in the porous body. The electrospinning method also has a solution type and a melt type, but the solution type capable of forming finer fibers is more preferable.

The spinning method based on this solution-type electrospinning method is a method in which a resin solution is stretched and made into fibers by applying an electric field to the resin solution supplied from a resin solution supply unit such as a nozzle to the spinning space.

Hereinafter, the fiber forming step of forming fibers by the electrospinning method will be described with reference to a schematic diagram showing an example of the configuration of the electrospinning apparatus of FIG.

The electrospinning device, which is the fiber manufacturing device of FIG. 1, is a resin solution supply device 1 that supplies the resin solution 3 to the nozzle 2, a nozzle 2 that discharges the resin solution 3, and a fiber that is discharged from the nozzle 2 and stretched by an electric field. A grounded collector 4 capable of collecting 9 is provided. Further, in this manufacturing apparatus, in order to form an electric field between the nozzle 2 and the grounded collector 4, a voltage applying device 5 capable of applying a voltage to the nozzle 2 and a spinning space are surrounded by a spinning container 6 and a spinning container. 6 is provided with an intake port 7 and an exhaust port 8 for exhausting the evaporated solvent. Further, in this manufacturing apparatus, an air conditioner (not shown) may be attached to the intake port 7 in order to adjust the temperature and humidity inside the spinning container 6.

When forming the fiber 9 using such a manufacturing apparatus, first, a resin solution 3 is prepared. This resin solution 3 is a solution in which an electrospinning resin is dissolved in a solvent.

The weight average molecular weight of the resin contained in the resin solution is preferably 10,000 to 1,000,000, and more preferably 100,000 to 500,000. When the weight average molecular weight of the resin is 10,000 or more, the resin solution discharged from the nozzle tends to become fibrous instead of bead-like, and when the weight average molecular weight is 1 million or less, the resin solution 3 becomes It is easy to be stretched and easily becomes fibrous.

The solvent constituting the resin solution 3 may be any solvent that can dissolve the resin, and is not particularly limited. For example, water, acetone, methyl isobutyl ketone, diisobutyl ketone, acetophenone, ethyl acetate, butyl acetate. , Methanol, ethanol, propanol, isopropanol, hexafluoroisopropanol, tetrahydrofuran, dimethyl sulfoxide, 1,4-dioxane, pyridine, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, acetonitrile, Examples thereof include formic acid, toluene, benzene, cyclohexane, cyclohexanone, carbon tetrachloride, methylene chloride, chloroform, trichloroethane, ethylene carbonate, diethyl carbonate, propylene carbonate and the like. In addition, these solvents can be used alone or in mixture.

Further, salts such as lithium chloride, lithium bromide, and sodium chloride, a surfactant, and the like may be added to the resin solution 3 as additives.

The resin solution 3 is obtained by dissolving the above-mentioned resin in the above-mentioned solvent. The resin concentration in the resin solution may be appropriately adjusted depending on the composition of the resin, the molecular weight of the resin, the solvent, etc., but is preferably 1% by mass or more and 50% by mass or less from the viewpoint of applicability to electrospinning. When the resin concentration in the resin solution is 1% by mass or more, the solvent tends to evaporate and the spinning raw material discharged from the nozzle tends to become fibrous. Further, when the resin concentration is 50% by mass or less, the spinning stock solution discharged from the nozzle is likely to be stretched and become fibrous without lowering the solubility of the resin.

Further, the resin solution 3 is supplied to the nozzle 2 by the resin solution supply device 1. The supplied resin solution 3 is extruded from the nozzle 2 and is subjected to a stretching action by an electric field between the grounded collector 4 and the nozzle 2 applied by the voltage applying device 5, and is fiberized toward the collector 4. Be jetted. Then, the injected fibers 9 are accumulated on the collector 4 to form an aggregate 10 of the fibers. The resin solution supply device 1 is not particularly limited, but for example, a syringe pump, a tube pump, a dispenser, or the like can be used.

The diameter of the nozzle 2 varies depending on the fiber diameter of the fiber 9 to be obtained, and is not particularly limited. For example, the diameter (inner diameter) is preferably 0.1 to 2.0 mm.

Further, the nozzle 2 may be made of metal or non-metal. If the nozzle 2 is made of metal, the nozzle 2 can be used as one of the electrodes by applying a voltage from the voltage applying device 5. When the nozzle 2 is made of non-metal, an electrode is installed inside the nozzle 2 or in the supply pipe from the spinning resin solution supply device 1 to the nozzle 2, and a voltage is applied to this electrode from the voltage application device 5. , An electric field can be applied to the extruded resin solution 3.

In FIG. 1, a voltage is applied to the nozzle 2 by the voltage applying device 5 and an electric field is formed by grounding the collector 4. However, the electric field is formed by grounding the nozzle 2 and applying a voltage to the collector 4. May be formed. Further, although the voltage is applied to both the nozzle 2 and the collector 4, the electric field may be formed by applying the voltage so as to provide a potential difference.

The voltage applying device 5 is not particularly limited, but for example, a DC high voltage generator or a Van de Graaff generator can be used. The applied voltage is not particularly limited, but is preferably 5 to 50 kV.

The collector 4 in FIG. 1 is a drum, but it is not particularly limited as long as it can accumulate fibers 9. For example, a non-woven fabric, a woven fabric, a knitted fabric, a net, a flat plate, or a belt made of a conductive material made of metal, carbon, or the like or a non-conductive material made of an organic polymer can be used as the collector 4.

The distance from the tip of the nozzle 2 to the collector 4 varies depending on the fiber diameter of the fiber 9 to be obtained and the amount of the residual solvent, and is not particularly limited, but may be, for example, 5 to 30 cm. preferable.

Further, the resin material can be obtained by obtaining a sheet-like material by a method such as extrusion molding and then stretching it to a predetermined thickness. Further, a porous film can be obtained by adding a plasticizer such as paraffin to the material at the time of extrusion molding and removing the plasticizer by heating or the like at the time of stretching. The pore size can be adjusted by appropriately adjusting the amount of the plasticizer to be added, the draw ratio, and the like.

The fiber diameter can be measured by SEM observation from the surface, or SEM observation after forming a cross section with an ion milling device, a focused ion beam device (FIB), or the like. In the present invention, the fiber diameter was calculated by measuring the diameters of 10 fibers that can be clearly identified by the SEM photograph and calculating the average value. The pore size was measured by a pore distribution measuring device, Composer 3 Gz (manufactured by Kantachrome). The thickness of the porous layer was obtained by measuring the thickness of any 10 points with a straight-ahead micrometer CLM1-15QM (manufactured by Mitutoyo) and calculating the average value. The porosity can be calculated from the volume, density and mass as follows. That is, it can be calculated by porosity (%) = (actual measured mass-volume of porous layer x density of resin) / (volume of porous layer x density of resin) x 100.

Further, it is preferable that the second porous layer has a larger capacity than the first porous layer so that more liquid components absorbed from the ink image can be taken in. Therefore, it is preferable that the fiber diameter of the second porous layer is larger than the fiber diameter of the first porous layer. Specifically, the fiber diameter of the second porous layer is preferably 1 μm or more and 10 μm or less, and more preferably 1 μm or more and 6 μm or less. Similarly, the pore size of the second porous layer is preferably larger than the pore size of the first porous layer. Specifically, the pore size of the second porous layer is preferably 1 μm or more and 100 μm or less, and more preferably 1 μm or more and 50 μm or less. The thickness of the second porous layer is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. The porosity of the second porous layer is preferably 40% or more, more preferably 60% or more. These measuring methods were carried out in the same manner as in the first porous layer.

As a method for producing the second porous layer, after forming a fleece by a dry method, a wet method, a spunbond method, a melt blow method, an electrosbinning method, etc., a chemical bond method, a thermal bond method, a needle punch method, and a water flow method are used. Examples thereof include a method of joining fibers by an entanglement method or the like. Among them, the electrospinning method is preferable as in the case of the first porous layer.

Regarding the air permeability of the porous body formed through the above steps, it is preferable that the galley value measured by the galley testing machine defined by JIS P8117 is 12 seconds or less. When the gullet value is 12 seconds or less, the image flow can be further suppressed.

(Inkjet recording device)
Next, an inkjet recording device that removes a liquid component from an ink image on an ejection medium using the porous body produced as described above will be described.

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

Each inkjet recording device will be described below.

(Transfer type inkjet recording device)
FIG. 2 is a schematic view showing an example of a schematic configuration of the transfer type inkjet recording device 100. This recording device is a single-wafer inkjet recording device that produces a recorded material by transferring an ink image to a recording medium 108 via a transfer body 101. In the present embodiment, the X direction, the Y direction, and the Z direction indicate the width direction (total length direction), the depth direction, and the height direction of the inkjet recording device 100, respectively. The recording medium P is conveyed in the X direction.

As shown in FIG. 2, the transfer-type inkjet recording device 100 reacts with a transfer body 101 supported by a support member 102 and a reaction solution application device 103 that applies a reaction solution that reacts with color ink on the transfer body 101. An ink application device 104 equipped with an inkjet head that applies colored ink onto the transfer body 101 to which the liquid has been applied and forms an ink image that is an image of the ink on the transfer body 101, and ink on the transfer body 101. It has a liquid absorbing device 105 that absorbs a liquid component from an image, and a transfer pressing member 106 for transferring an ink image on a transfer body 101 from which the liquid component has been removed onto a recording medium 108 such as paper. Further, the transfer type inkjet recording device 100 may have a transfer body cleaning member 109 that cleans the surface of the transfer body 101 after transfer, if necessary. As a matter of course, the transfer body 101, the reaction liquid application device 103, the inkjet head of the ink application device 104, the liquid absorption device 105, and the transfer body cleaning member 109 each correspond to the recording medium 108 used in the Y direction. Has a length of

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

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

Explaining the removal of the liquid component from a different viewpoint, it can also be expressed as concentrating the ink constituting the image formed on the transfer body 101. Concentrating the ink means that the liquid component contained in the ink is reduced, so that the content ratio of the solid content such as the coloring material and the resin contained in the ink to the liquid component is increased.

Then, the ink image after the liquid removal from which the liquid component has been removed is in a state where the ink is concentrated as compared with the ink image before the liquid removal, and the recording medium is further conveyed by the transfer body 101 by the recording medium transfer device 107. It is moved to the transfer unit 110 that comes into contact with 108. While the ink image after removing the liquid is in contact with the recording medium 108, the pressing member 106 presses the transfer body 101, so that the ink image is transferred onto the recording medium 108. The post-transcriptional ink image transferred onto the recording medium 108 is an inverted image of the ink image before liquid removal and the ink image after liquid removal.

In the present embodiment, since the reaction liquid is applied onto the transfer body 101 and then the ink is applied to form an image, the reaction liquid reacts with the ink in the non-image region where the image by the ink is not formed. It remains without. In this apparatus, the liquid absorbing member 105a is in contact with not only the image but also the unreacted reaction liquid, and the liquid component of the reaction liquid is also removed.

Therefore, in the above, it is expressed and explained that the liquid component is removed from the image, but it does not mean that the liquid component is removed only from the image, and at least the liquid component is removed from the image on the transfer body 101. It is used in the sense that it should be done.

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

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

Each configuration of the transfer type inkjet recording apparatus 100 of this embodiment will be described below.

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

Further, the transfer material 101 preferably has a compression layer having a function of absorbing pressure fluctuations. By providing the compression layer, the compression layer absorbs the deformation, disperses the fluctuation against local pressure fluctuations, and can maintain good transferability even during high-speed printing. Examples of the member of the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, silicone rubber and the like. At the time of molding the rubber material, it is preferable that a predetermined amount of a vulcanizing agent, a vulcanization accelerator or the like is blended, and further, a foaming agent, hollow fine particles or a filler such as salt is blended as necessary to make the rubber material porous. As a result, since the bubble portion is compressed with a volume change in response to various pressure fluctuations, deformation in directions other than the compression direction is small, and more stable transferability and durability can be obtained. As the porous rubber material, there are a continuous pore structure in which each pore is continuous with each other and an independent pore structure in which each pore is independent. In the present invention, any structure may be used, and these structures may be used in combination.

Further, the transfer body 101 preferably has an elastic layer between the surface layer and the compression layer. As the member of the elastic layer, various materials such as resin and ceramic can be appropriately used. Various elastomer materials and rubber materials are preferably used in terms of processing characteristics and the like. Specifically, for example, the common weight of fluorosilicone rubber, phenylsilicone rubber, fluororubber, chloroprene rubber, urethane rubber, nitrile rubber, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, and ethylene / propylene / butadiene. Combined, nitrile butadiene rubber and the like can be mentioned. In particular, silicone rubber, fluorosilicone rubber, and phenylsilicone rubber are preferable in terms of dimensional stability and durability because they have a small compression set. In addition, the change in elastic modulus with temperature is small, which is preferable in terms of transferability.

Various adhesives or double-sided tape may be used between the layers (surface layer, elastic layer, compression layer) constituting the transfer body 101 to fix and hold them. Further, a reinforcing layer having a high compressive elastic modulus may be provided in order to suppress lateral elongation when mounted on the device and to maintain elasticity. Further, the woven fabric may be used as a reinforcing layer. The transfer body 101 can be produced by arbitrarily combining the layers made of the above materials.

The size of the transfer body 101 can be freely selected according to the target print image size. The shape of the transfer body 101 is not particularly limited, and specific examples thereof include a sheet shape, a roller shape, a belt shape, and an endless web shape.

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

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

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

The reaction solution applying device 103 may be any device capable of applying the reaction solution onto the discharge medium, and various conventionally known devices can be appropriately used. Specific examples thereof include a gravure offset roller, an inkjet head, a die coating device (die coater), and a blade coating device (blade coater). The reaction solution is applied by the reaction solution application device 103 before the ink is applied or after the ink is applied, as long as it can be mixed (reacted) with the ink on the ejected medium. Preferably, the reaction solution is applied before applying the ink. By applying the reaction solution before applying the ink, bleeding in which the adjacently applied inks are mixed with each other during image recording by the inkjet method, and bee in which the ink that has landed first is attracted to the ink that has landed later. It is also possible to suppress the ding.

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

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

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

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

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

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

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

In this embodiment, an inkjet head is used as the ink applying device 104 that applies ink. Examples of the inkjet head include a form in which a film is boiled in the ink by an electric-heat converter to form bubbles to eject the ink, a form in which the ink is ejected by an electric-mechanical converter, and an ink using static electricity. Examples thereof include a discharge form. In this embodiment, a known inkjet head can be used. Among them, those using an electric-heat converter are preferably used from the viewpoint of high-speed and high-density printing. Drawing receives an image signal and applies the required amount of ink to each position.

In the present embodiment, the inkjet head is a full-line head extended in the Y direction, and nozzles are arranged in a range covering the width of the image recording area of the maximum usable recording medium. The inkjet head has an ink ejection surface having a nozzle opened on its lower surface (transfer body 101 side), and the ink ejection surface faces the surface of the transfer body 101 with a minute gap (about several millimeters). ..

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

The ink applying device 104 may have a plurality of inkjet heads in order to apply color inks of each color on the ejected medium. For example, when forming each color image using yellow ink, magenta ink, cyan ink, and black ink, the ink applying device 104 has four inkjet heads for ejecting the above four types of ink onto the ejected medium. It will be. These inkjet heads are arranged so as to line up in 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 contains a coloring material, the proportion thereof is very low, and a substantially transparent clear ink is ejected. Then, this clear ink can be used to form an ink image together with the reaction liquid and the color ink. For example, this clear ink can be used to improve the glossiness of an image. It is advisable to appropriately adjust the resin components to be blended so that the transferred image has a glossy appearance, and further control the ejection position of the clear ink. Since it is desirable that the clear ink is on the surface layer side of the color ink in the final recorded matter, in the transfer body type recording device, the clear ink is applied on the transfer body 101 before the color ink. Therefore, the inkjet head for clear ink can be arranged on the upstream side of the inkjet head for color ink in the moving direction of the transfer body 101 facing the ink applying device 104.

In addition to the glossy image, it can be used to improve the transferability of the image from the transfer body 101 to the recording medium 108. For example, the clear ink can be used as a transferability improving liquid to be imparted onto the transfer body 101 by containing a larger amount of a component that exhibits adhesiveness than the color ink and applying this to the color ink. For example, in the moving direction of the transfer body 101 facing the ink applying device 104, an inkjet head for clear ink for improving transferability is arranged on the downstream side of the inkjet head for color ink. Then, after the color ink is applied to the transfer body 101, the clear ink is applied on the transfer body 101 after the color ink is applied, so that the clear ink is present on the outermost surface of the ink image. In the transfer of the ink image to the recording medium 108 by the transfer unit 110, the clear ink on the surface of the ink image adheres to the recording medium 108 with a certain degree of adhesive force, whereby the ink image after liquid removal is transferred to the recording medium 108. It will be easier to move.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

<Liquid absorber>
In the present embodiment, the liquid absorbing device 105 has a liquid absorbing member 105a and a liquid absorbing pressing member 105b that presses the liquid absorbing member 105a against the ink image on the transfer body 101. The liquid absorbing member 105a moves in the direction of arrow B in FIG. The shapes of the liquid absorbing member 105a and the pressing member 105b are not particularly limited. For example, as shown in FIG. 2, the pressing member 105b has a cylindrical shape, the liquid absorbing member 105a has a belt shape, and the cylindrical pressing member 105b presses the belt-shaped liquid absorbing member 105a against the transfer body 101. It may be a configuration. Further, the pressing member 105b has a cylindrical shape, the liquid absorbing member 105a has a cylindrical shape formed on the peripheral surface of the cylindrical pressing member 105b, and the cylindrical pressing member 105b has a cylindrical liquid absorbing member 105a. May be pressed against the transfer body.

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

Further, the liquid absorbing device 105 having such a belt-shaped liquid absorbing member 105a may have a stretching member for stretching the liquid absorbing member 105a. In FIG. 2, 105c is a tension roller as a tension member. In FIG. 2, the pressing member 105b is also a roller member that rotates in the same manner as the tension roller, but the present invention is not limited to this.

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

<Liquid absorption member>
In the present embodiment, at least a part of the liquid component is removed from the ink image before the liquid removal by contacting with the liquid absorbing member 105a having a porous body to absorb the liquid component, and the content of the liquid component in the ink image is reduced. Reduce. The contact surface of the liquid absorbing member 105a with the ink image is set as the first surface, and the porous body is arranged on the first surface. The liquid absorbing member 105a having such a porous body moves in conjunction with the movement of the ejected medium, comes into contact with the ink image, and then re-contacts another ink image before removal of the liquid at a predetermined cycle. It is preferable that the ink has a shape capable of absorbing the liquid. For example, a shape such as an endless belt shape or a drum shape can be mentioned.

(Porous medium)
As the porous body of the liquid absorbing member 105a, a porous body for an inkjet recording device produced by the above-mentioned production method is used. The shape of the porous body is not particularly limited, and examples thereof include a film shape (also referred to as a porous membrane) and a roll shape. In the present embodiment, the first porous layer containing the fluororesin of the porous body is arranged so as to be in contact with the ink image.

Further, the liquid absorbing member 105a has, in addition to the above-mentioned porous body, a support member for supporting the second surface side of the above-mentioned porous body and a reinforcing member for reinforcing the side surface of the liquid absorbing member 105a. May be good. Further, it may have a joining member for connecting the longitudinal end portions of a long sheet-shaped porous body to form a belt-shaped member. As such a material, a non-porous tape material or the like can be used, and it may be arranged at a position or a period that does not come into contact with the image. The method of laminating the porous body and the support member or the reinforcing member to form the liquid absorbing member 105a is not particularly limited, but may be simply laminated, or may be adhesive laminated or heat laminated. They may be adhered to each other by using a method such as.

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

(Preprocessing)
In the present embodiment, before the liquid absorbing member 105a having a porous body is brought into contact with the ink image, the pretreatment is performed by a pretreatment means (not shown in FIGS. 2 and 3) for applying the treatment liquid to the liquid absorbing member 105a. It is preferable to apply. The treatment liquid used in this embodiment preferably contains water and a water-soluble organic solvent. The water is preferably water that has been deionized by ion exchange or the like. The type of water-soluble organic solvent is not particularly limited, and any known organic solvent such as ethanol or isopropyl alcohol can be used. In the pretreatment of the liquid absorbing member 105a used in the present embodiment, the application method is not particularly limited, but immersion or dropping of droplets is preferable.

(Pressurization condition)
If the pressure of the liquid absorbing member 105a at the time of contact with the ink image on the transfer body 101 is 2.9 N / cm ² (0.3 kgf / cm ² ) or more, the liquid component in the ink image can be used for a shorter time. It is preferable because it can be solid-liquid separated and the liquid component can be removed from the ink image. The pressure of the liquid absorbing member 105a in the present specification indicates the nip pressure between the discharge medium and the liquid absorbing member, and is a surface pressure distribution measuring instrument (“I-SCAN”, manufactured by Nitta Co., Ltd.). ) Was used to measure the surface pressure, and the weight in the pressurized region was divided by the area to calculate the value.

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

In this way, the liquid component is absorbed on the transfer body 101, and an ink image in which the liquid component is reduced is formed. The ink image after removing the liquid is then transferred onto the recording medium 108 by the transfer unit 110. The apparatus configuration and conditions at the time of transfer will be described.

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

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

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

Further, the pressure at which the pressing member 106 presses the transfer body 101 in order to transfer the ink image after removing the liquid on the transfer body 101 to the recording medium 108 is not particularly limited, but the transfer is performed well and the transfer is performed. The durability of the body 101 is not impaired. Therefore, the pressure ^{is preferably 9.8 N / cm 2} (1 kg / cm ² ) or more and 294.2 N / cm ² (30 kg / cm ² ) or less. The pressure in the present embodiment indicates the nip pressure between the recording medium 108 and the transfer body 101, the surface pressure is measured using a surface pressure distribution measuring device, and the load in the pressure region is divided by the area. The value is calculated.

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

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

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

Further, in the transfer type inkjet recording device 100 of the present embodiment, the recording medium 108 is conveyed by the recording medium conveying device 107 in the direction of the arrow C. In FIG. 2, the recording medium transport device 107 for transporting the recording medium 108 is composed of a recording medium feeding roller 107a and a recording medium winding roller 107b, but it is only necessary to be able to transport the recording medium, and the configuration is particularly limited to this configuration. It is not something that is done.

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

FIG. 3 is a schematic view showing an example of a schematic configuration of the direct drawing type inkjet recording device 200. Compared with the transfer type inkjet recording device 100 described above, the direct drawing type inkjet recording device 200 does not have the transfer body 101, the support member 102, and the transfer body cleaning member 109, and forms an image directly on the recording medium 208. Except for the point, it has the same means as the transfer type inkjet recording device 100.

Therefore, the ink image is formed by the reaction liquid applying device 203 that applies the reaction liquid to the recording medium 208, the ink applying device 204 that applies ink to the recording medium 208, and the liquid absorbing member 205a that comes into contact with the ink image on the recording medium 208. The liquid absorbing device 205 that absorbs the liquid component contained in the above has the same configuration as the transfer type inkjet recording device 100, and the description thereof will be omitted.

The reaction solution application device 203 of FIG. 3 has a reaction solution accommodating unit 203a for accommodating the reaction solution, and reaction solution application members 203b and 203c for applying the reaction solution in the reaction solution accommodating unit 203a onto the recording medium 208. The case of a gravure offset roller is shown.

Further, the liquid absorbing device 205 of FIG. 3 shows a case where the liquid absorbing member 205a and the pressing member 205b for liquid absorbing which presses the liquid absorbing member 205a against the ink image on the recording medium 208 are provided. The shapes of the liquid absorbing member 205a and the pressing member 205b are not particularly limited, and those having the same shape as the liquid absorbing member and the pressing member that can be used in the transfer type inkjet recording device 100 can be used. Further, the liquid absorbing device 205 may have a tensioning member for tensioning the liquid absorbing member 205a. In FIG. 3, 205c, 205d, 205e, 205f, and 205g are tension rollers as tension members, and the liquid absorption member moves in the direction of arrow B. The number of tension rollers is not limited to the five in FIG. 3, and the required number may be arranged according to the device design. Further, recording is performed on the ink applying unit that applies ink to the recording medium 208 by the ink applying device 204 and the liquid component removing unit that contacts the liquid absorbing member 205a with the ink image on the recording medium 208 to remove the liquid component. A recording medium support member (not shown) that supports the medium 208 from below may be provided.

<Recording medium and recording medium transfer device>
In the present embodiment, the recording medium 208 can be the same as that used in the transfer type inkjet recording device.

In the direct drawing type inkjet recording device 200 of the present embodiment, the recording medium 208 is conveyed by the recording medium transfer device 207 in the direction of arrow A. The recording medium transfer device 207 is not particularly limited, and a transfer means in a known direct drawing type inkjet recording device can be used. As an example, as shown in FIG. 3, a recording medium transfer device having a recording medium feeding roller 207a, a recording medium winding roller 207b, and a recording medium transfer roller 207c, 207d, 207e, 207f can be mentioned.

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

<Preparation of porous body>
As the first porous layer, porous layers a-1 to a-3 and b-1 having the fluororesins, Tg, Tm, fiber diameter, thickness, pore diameter, and galley value shown in Table 1 below are prepared. did. The method for producing the first porous layer is as follows.

As the first resin contained in the first porous layer, an ethylene tetrafluoride-propylene hexafluoride-vinylidene difluoride (TFE-HFP-VDF) copolymer and polytetrafluoroethylene (PTFE) were prepared. The values of Tm and Tg of these resins were measured by a differential scanning calorimetry machine (DSC) defined by JIS K7121.

In the first porous layer a-1, first, a 20 mass% dimethylacetamide / methyl isobutyl ketone (mass ratio: 5/5) solution of the TFE-HFP-VDF copolymer was prepared. A resin solution 1 was prepared by adding 0.01% by mass lithium chloride to this solvent. Then, this resin solution 1 was set in the resin solution supply device 1 of the electrospinning device shown in FIG. A stainless steel nozzle having an inner diameter of 0.22 mm was used. An aluminum collector was used as the collector 4, and the distance between the nozzle 2 and the collector 4 was set to 15 cm. Next, a voltage was applied from the voltage applying device 5 in the range of 20 to 30 kV to start spinning. The supply amount of the resin solution 1 at this time was set to 1 ml / h. The fiber aggregate 10 thus obtained was peeled off from the collector 4. The obtained fiber aggregate 10 is heat-treated at 122 ° C. using a clean oven DES-82 (manufactured by Yamato Scientific Co., Ltd.), and is the first porous material having the fiber diameter, pore diameter, thickness, and gullet value shown in Table 1. A layer was formed. Further, in the first porous layers a-2 and a-3, the supply amount of the resin solution 1 of the porous layer a-1 is adjusted to satisfy the fiber diameter, pore diameter, thickness, and galley value shown in Table 1. It was prepared in the same manner as the porous layer a-1 except that it was adjusted.

The first porous body b-1 is a stretched membrane made of PTFE. This was produced by compression-molding the crystallized PTFE emulsified polymer particles, stretching them at a temperature below the melting point, and then subjecting them to a thermal pressure calendar treatment to obtain a fibrillated porous layer.

The fiber diameter was determined by measuring the diameters of 10 fibers that can be clearly identified in the SEM photograph and calculating the average value. The pore size was measured by a pore distribution measuring device, Composer 3 Gz (manufactured by Kantachrome). The thickness of the porous layer was obtained by measuring the thickness of any 10 points with a straight-ahead micrometer CLM1-15QM (manufactured by Mitutoyo) and calculating the average value. Further, the galley value of the porous layer was measured by a galley testing machine defined by JIS P8117.

Next, as the second porous layer, the porous layers c-1 to c-3 and d-1 having the resins, Tg, Tm, fiber diameter, thickness, pore diameter, and galley value shown in Table 2 below. Was produced. The method for producing the second porous layer is as follows.

Polyethylene (PE) and polystyrene (PS) were prepared as the second resin contained in the second porous layer.

The second porous layer c-1 to c-3 is a porous layer obtained by a melt blow method of polyethylene (PE). These are formed by extruding fibers from a nozzle while blowing hot air onto the molten polyethylene to form fibers and entangle them, and then further apply a thermal pressure calendar treatment to obtain the fiber diameters, pore diameters, thicknesses, and galley values shown in Table 2. It was prepared so as to be a porous layer having.

Further, for the second porous layer d-1, first, a resin solution 2 in which 0.05 mass% lithium chloride was added to a polystyrene (PS) 18 mass% N, N-dimethylformamide solution was prepared, and a resin supply device was prepared. It was set to 1. A stainless steel nozzle having an inner diameter of 0.22 mm was used. An aluminum collector was used as the collector 4, and the distance between the nozzle 2 and the collector 4 was set to 15 cm. Next, a voltage was applied from the voltage applying device 5 in the range of 15 to 25 kV to start spinning. The supply amount of the resin solution 2 at this time was set to 1 ml / h. The fiber aggregate 10 thus obtained was peeled off from the collector 4. The obtained fiber aggregate 10 was heat-treated at 100 ° C. using a clean oven DES-82 (manufactured by Yamato Scientific Co., Ltd.), and the second porous material having the fiber diameter, pore diameter, thickness, and gullet value shown in Table 1 was obtained. A layer was formed. The physical property values of the second porous layer were measured by the same method as that of the first porous layer described above. Further, PS is a non-crystalline resin and is a resin having no melting point.

In the combination of the first porous layer and the second porous layer shown in Table 3, the first porous layer and the second porous layer were superposed and heated to form a laminate. .. Then, surface treatment is applied to the surface of the first porous layer and the surface of the second porous layer on the side where the first porous layer and the second porous layer are in contact with each other in the laminate. , Examples 1 to 17 and Comparative Examples 1 to 5, respectively, were prepared.

Table 3 shows the production conditions of the porous body in Examples 1 to 17 and Comparative Examples 1 to 5 and the galley value of the obtained porous body. The galley value was measured using a galley testing machine according to JIS P8117.

In the heat treatment step of heating the first porous layer and the second porous layer in a superposed state, when only the heat treatment is performed, a clean oven DES-82 (manufactured by Yamato Scientific Co., Ltd.) is used for heat and pressure treatment. Labpress T15 (manufactured by Toyo Seiki Seisakusho) was used. Table 3 shows the heating temperature and pressure during the heat treatment and the heat pressurization treatment.

Further, in the surface treatment step after the heat treatment step, when plasma treatment is performed on the laminate of the first porous layer and the second porous layer, the atmospheric pressure plasma surface treatment apparatus AP-T05 -S440 (manufactured by Sekisui Chemical Co., Ltd.) was used. The plasma treatment at this time was performed under the conditions of a direct method, an irradiation distance of 1.0 mm, a power of 380 W, a frequency of 10 kHz, and a processing speed of 100 mm / min. The IR spectrum of the surface of the plasma-treated porous layer was measured, and it was confirmed that the porous layer had a hydrophilic group.

Similarly, when the corona treatment was performed, a corona surface modification evaluation device TEC-4AX (manufactured by Kasuga Electric Works Ltd.) was used. The corona treatment at this time was performed under the conditions that the irradiation speed was 500 mm / min, the irradiation distance was 1 mm, and the corona discharge amount was 50 W · min / m ^2. Similarly, the IR spectrum of the surface of the corona-treated porous layer was measured, and it was confirmed that the porous layer had a hydrophilic group.

The "direction of surface treatment" in Table 3 indicates which side of the surface of the first porous layer or the surface of the second porous layer when the surface treatment is performed on the laminated body after the heat treatment. Indicates whether the process was performed from.

Further, "water repellent treatment" in Table 3 indicates the presence or absence of water repellent treatment after the surface treatment step. When the water repellent treatment was performed after the surface treatment step, the water repellent treatment was performed by applying a fluorine-based water repellent agent Novec1720 (manufactured by 3M Japan Ltd.) as a water repellent to the surface of the first porous layer.

<Inkjet recording device and image formation>
Next, the liquid absorbing member 105a having the porous body produced above was image-recorded using the transfer-type inkjet recording device 100 of FIG.

The transfer body 101 in this embodiment is fixed to the support member 102 with an adhesive.

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

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

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

The reaction solution given by the reaction solution giving means 103 had the following composition, and the amount given was 1 g / m ² . The balance of the ion-exchanged water is an amount in which the total of all the components constituting the reaction solution is 100.0 parts by mass.
・ 21.0 parts by mass of glutaric acid ・ 2.0 parts by mass of potassium hydroxide ・ 5.0 parts by mass of glycerin ・ Surfactant (Product name: Megafuck F444, 5.0 parts by mass manufactured by DIC Corporation ・ Remaining ion-exchanged water The ink was prepared as follows.

(Preparation of pigment dispersion)
Carbon black (product name: Monac 1100, manufactured by Cabot), 10 parts of resin aqueous solution (styrene-ethyl acrylate-acrylic acid copolymer, acid value 150, weight average molecular weight (Mw) 8,000, resin content 20 15 parts of 0.0% by mass aqueous solution neutralized with potassium hydroxide aqueous solution) and 75 parts of pure water were mixed and charged into a batch type vertical sand mill (manufactured by IMEX), and 200 parts of 0.3 mm diameter zirconia beads were added. The dispersion treatment was carried out for 5 hours while being filled and cooled with water. After centrifuging this dispersion to remove coarse particles, a black pigment dispersion having a pigment content of 10.0% by mass was obtained.

(Preparation of resin particle dispersion)
20 parts of ethyl methacrylate, 3 parts of 2,2'-azobis- (2-methylbutyronitrile) and 2 parts of n-hexadecane were mixed and stirred for 0.5 hours. This mixture was added dropwise to 75 parts of an 8% aqueous solution of a styrene-butyl acrylate-acrylic acid copolymer (acid value: 130 mgKOH / g, weight average molecular weight (Mw): 7,000), and the mixture was stirred for 0.5 hours. did. Next, ultrasonic waves were irradiated with an ultrasonic irradiator for 3 hours. Subsequently, a polymerization reaction was carried out at 80 ° C. for 4 hours in a nitrogen atmosphere, and the mixture was cooled to room temperature and then filtered to prepare a resin particle dispersion having a resin content of 25.0% by mass.

(Ink preparation)
The resin particle dispersion and the pigment dispersion obtained above were mixed with the following components. The balance of the ion-exchanged water is an amount in which the total of all the components constituting the ink is 100.0 parts by mass.
-Pigment dispersion (content of coloring material is 10.0% by mass) 40.0 parts by mass-Resin particle dispersion 20.0 parts by mass-Glycerin 7.0 parts by mass-Polyethylene glycol (number average molecular weight (Mn): 1,000) 3.0 parts by mass, surfactant acetylenol E100 (manufactured by Kawaken Fine Chemicals Co., Ltd.) 0.5 parts by mass, ion-exchanged water balance After sufficiently stirring and dispersing this, a microfilter with a pore size of 3.0 μm Black ink was prepared by pressure filtration with (manufactured by Fujifilm Co., Ltd.).

The ink applying means 104 used an inkjet head of a type that ejects ink by an on-demand method using an electric-heat conversion element, and the amount of ink applied was 20 g / m ² .

The liquid absorbing member 105a is adjusted to have a speed equivalent to the moving speed of the transfer body 101 by a transport roller 105c that transports the liquid absorbing member while stretching it. Further, the recording medium 108 is conveyed by the recording medium feeding roller 107a and the recording medium winding roller 107b so as to have a speed equivalent to the moving speed of the transfer body 101. In this example, the transport speed was 0.5 m / s, and Aurora-coated paper (manufactured by Nippon Paper Industries, Ltd., basis weight 104 g / m ² ) was used as the recording medium 108.

In this example, the liquid absorbing member 105a was immersed in a treatment liquid consisting of 95 parts of ethanol and 5 parts of water, permeated, replaced with a liquid consisting of 100 parts of water, and then used for removing the liquid.

Further, the nip pressure between the transfer body 101 and the liquid absorbing member 105a is applied to the liquid absorbing member 105a by the liquid absorbing pressing member 105b so that the ^{average pressure is 2 kg / cm 2.}

[Evaluation]
The porous body obtained above was evaluated by the following evaluation method. The evaluation results are shown in Table 4. In this example, AA to B of the evaluation criteria of each of the following evaluation items were set as preferable levels, and C was set as an unacceptable level.

<Image flow>
The amount of movement of the coloring material at the edge of the image after the liquid is removed under the above-mentioned conditions is shown, and the smaller the amount of movement, the higher the image quality, which is preferable. The amount of image flow is affected by the flow resistance, and it is preferable that the galley value of the liquid absorbing member is low. The evaluation criteria are as follows.

AA: No image flow was observed even after repeated use 100 times.

A: No image flow was observed after one use.

B: There was a slight image flow, but it was a level that was not noticeable.

C: The image flow was large.

<Adhesiveness>
After removing the liquid, observe the presence or absence of delamination between the first porous layer and the second porous layer of the porous body, and adhere the first porous layer to the second porous layer. Gender was evaluated. The evaluation criteria are as follows.

A: No peeling between layers occurred even after repeated use 100 times.

B: No peeling between layers occurred after one use.

C: Peeling occurred between the layers.

Table 4 shows a list of the above evaluation results.

1 Resin solution supply device 2 Nozzle 3 Resin solution 4 Collector 5 Voltage application device 6 Spinning container 7 Intake port 8 Exhaust port 9 Fiber 10 Fiber aggregate

Claims (8)

A heat treatment step of forming a laminate by heating a first porous layer having a first resin and a second porous layer having a second resin in a state of being overlapped with each other.
Surface treatment on the surface of the first porous layer and the surface of the second porous layer on the side where the first porous layer and the second porous layer are in contact with each other in the laminate. Surface treatment process and
It is a method for producing a porous body for an inkjet recording device having the above.
Of the first resin and the second resin, the lowest melting point (Tm) in the case of a crystalline resin and the glass transition point (Tg) in the case of a non-crystalline resin (the lowest). When the resin having Tm) or the glass transition point (Tg) is the resin (A), the heating temperature in the heat treatment step is
When the resin (A) is a crystalline resin, it is Tm or more and Tm + 30 ° C. or less.
When the resin (A) is a non-crystalline resin, it is Tg or more and Tg + 30 ° C. or less.
In the surface treatment step, the surface of the first porous layer or the second porous layer on the side where the first porous layer and the second porous layer in the laminate are not in contact with each other. A method for producing a porous body for an inkjet recording apparatus, which comprises a step of performing a surface treatment of either plasma treatment or corona treatment from the surface of the layer. The method for producing a porous body for an inkjet recording device according to claim 1, wherein the heat treatment step is a heat and pressure treatment step. The heating temperature in the heat treatment step is
When the resin (A) is a crystalline resin, it is Tm or more and Tm + 20 ° C. or less.
The method for producing a porous body for an inkjet recording device according to claim 1 or 2, wherein when the resin (A) is a non-crystalline resin, the temperature is Tg or more and Tg + 20 ° C. or less. The surface treatment according to any one of claims 1 to 3, wherein the surface treatment is applied from the surface of the first porous layer and the second porous layer on the porous layer side having a low galley value. A method for producing a porous body for an inkjet recording device. The surface treatment is any one of claims 1 to 4 applied from the surface of the first porous layer and the second porous layer on the porous layer side having a galley value of 5 seconds or less. The method for producing a porous body for an inkjet recording device according to the item. The method for producing a porous body for an inkjet recording device according to any one of claims 1 to 5, wherein the first resin is a fluororesin. The method for producing a porous body for an inkjet recording device according to any one of claims 1 to 6, wherein the fluororesin is polytetrafluoroethylene. In the surface treatment step, the surface treatment is applied from the surface of the first porous layer having the fluororesin.
After the surface treatment step, the surface on the side of the first porous layer on the side where the first porous layer and the second porous layer in the laminate are not in contact with each other is water repellent. The method for producing a porous material for an inkjet recording apparatus according to claim 6 or 7, wherein the processing step is performed.

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