JP2009000915A - Ink jet recording device and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely eliminate a solvent without causing a deviation of a color material. <P>SOLUTION: This ink jet recording device comprises a processing solution applying section for applying a processing solution onto an intermediate transfer body; an image forming section that discharges ink to the intermediate transfer body from an ink jet type recording head; a solvent eliminating section having at least two solvent eliminating rollers arranged in sequence along the conveyed direction of the intermediate transfer body, and bringing the solvent eliminating rollers into contact with the surface of the intermediate transfer body while rotating the solvent eliminating rollers to eliminate the solvent; and an image transfer section for transferring an image formed on the intermediate transfer body, to a recording medium. The first solvent eliminating roller arranged upstream in the conveyed direction of the intermediate transfer body is a porous body roller composed of a first porous body at least on the surface, or a plane roller with no pore formed on the surface, and the pore diameter or numerical aperture of a second porous body is formed to be smaller compared with the first porous body. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and a recording method, and in particular, an ink jet recording apparatus and a recording apparatus that perform image transfer from an intermediate transfer body to a recording medium after forming an image on an intermediate transfer body using an ink jet recording head. Regarding the method.

  2. Description of the Related Art Conventionally, an ink jet recording apparatus that performs image recording on a recording medium by ejecting ink droplets from a large number of nozzles formed on an ink jet recording head (ink jet head) is known. 2. Description of the Related Art Inkjet recording apparatuses are widely used because they are excellent in low noise performance, have low running costs, and can record high-quality images on a wide variety of recording media.

  Ink used in an inkjet recording head is generally composed of a liquid solvent (hereinafter simply referred to as “solvent”) as a main component, and therefore, after ink droplets ejected from the recording head have landed on the recording medium, If the solvent contained in the ink is not removed sufficiently, it may cause a setback to another recording medium, or the recording medium may absorb the solvent and cause curling or cockle. .

  Many techniques for removing the solvent on the recording medium have been proposed so far. For example, methods using means such as heating and ventilation are known, but these methods are unsuitable for high-speed recording because it takes time to remove the solvent, resulting in a large amount of power consumption and an increase in the size of the apparatus. . Further, in the method of absorbing the solvent by bringing the absorbing member typified by so-called “absorbing paper” into contact with the surface of the intermediate transfer member, the coloring material is also absorbed together with the solvent, which causes deterioration of image quality. Become.

  Therefore, in order to solve such a problem, Japanese Patent Application Laid-Open No. H10-260260 covers the ink coloring material and a member having a releasability (release member) for the purpose of absorbing only the solvent on the recording medium. A technique is disclosed in which the absorber is made to absorb only the solvent through the release member by bringing the absorbent body close to the recording medium portion to which the ink has adhered.

In Patent Document 2, as an improved technique of Patent Document 1, a hydrophilic absorption layer is formed on the surface of the absorber, and only the solvent is passed through the hydrophilic absorption layer without degrading the image quality. A technique for absorbing water is disclosed.
JP 2001-179959 A JP 2005-271400 A

  In order to realize high-quality image formation in an ink jet recording apparatus, regardless of the type of recording medium, an image is formed on the intermediate transfer member by discharging ink from the recording head to the intermediate transfer member. Some employ an image transfer method (intermediate transfer method) for transferring an image from an intermediate transfer member to a recording medium.

  In such an intermediate transfer type inkjet recording apparatus, it is necessary to sufficiently remove the solvent on the intermediate transfer member before image transfer from the intermediate transfer member to the recording medium. If solvent removal before image transfer is insufficient, an image containing a large amount of solvent is transferred to a recording medium, which causes the same problem as when ink is directly ejected onto a recording medium.

  In particular, a treatment liquid (color material aggregation liquid) containing a component that aggregates the color material in the ink is applied before (or after) ink droplets have landed on the intermediate transfer body, and the ink and In the case of a system (two-liquid reaction system) in which the colorant is aggregated by forming a reaction by mixing the processing liquid to form an image on the intermediate transfer member and then transferring the image to the recording medium (two-liquid reaction system). Since the solvent contained in the medium is also added on the intermediate transfer member, the total amount of the solvent on the intermediate transfer member increases, and the above problem becomes a more serious problem.

  According to the study of the present inventor, the solvent was removed by contacting the solvent on the intermediate transfer member while rotating the solvent removing roller (porous member) having a porous surface. However, when the intermediate transfer body is transported at high speed, the pore diameter of the porous body is small. If too much, the solvent could not be absorbed by the porous body and squeezed, thereby causing color material misalignment. On the other hand, if the pore size of the porous body is too large, the solvent is left behind in the coloring material, and the solvent cannot be sufficiently removed from the intermediate transfer member.

  In this specification, “squeeze” means a state in which the solvent overflows in the vicinity where the solvent removal roller and the intermediate transfer member are in contact with each other without absorbing the solvent. “Color material misalignment” means that when a solvent is absorbed by a porous body having a small pore diameter, the absorption power is strong, so that the force to tear the 1-dot color material to try to absorb the solvent inside the color material. In addition, the coloring material is displaced or torn off by the force, and the coloring material moves together with the solvent overflowed when squeezing occurs.

  In the techniques disclosed in Patent Documents 1 and 2, the above-described viewpoints are not taken into consideration at all, and it is difficult to reliably remove the solvent without causing color material displacement.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an ink jet recording apparatus and a recording method capable of reliably removing a solvent without causing a color material shift.

  In order to achieve the above object, the invention according to claim 1 is directed to an ink and a treatment liquid containing a component that agglomerates the coloring material in the ink on the intermediate transfer member while conveying the intermediate transfer member. In the ink jet recording apparatus, the color material is agglomerated to form an image on the intermediate transfer member by transferring the mixture, and the image is transferred from the intermediate transfer member to a recording medium. At least two solvents along the transport direction of the intermediate transfer body, a processing liquid application section that is applied onto the intermediate transfer body, an image forming section that discharges ink from the inkjet recording head to the intermediate transfer body, and A removal roller is arranged in order, and while rotating the solvent removal roller, a solvent removal unit that contacts the surface of the intermediate transfer member to remove the solvent from the intermediate transfer member, and a shape on the intermediate transfer member An image transfer unit that transfers the image to the recording medium, and the first solvent removal roller disposed on the upstream side in the transport direction of the intermediate transfer body has at least a surface formed of a first porous body. The second solvent removal roller disposed on the downstream side is a porous roller having at least a surface made of the second porous body, or a flat roller having no hole formed on the surface, and is the first roller. Provided is an ink jet recording apparatus characterized in that the second porous body has a smaller pore diameter or aperture ratio than a porous body.

  According to the present invention, the first solvent removal roller (porous roller) disposed on the upstream side in the conveyance direction of the intermediate transfer body absorbs the solvent around the color material and stabilizes the color material, and then the downstream side. In addition to the residual solvent on the intermediate transfer member, the second solvent removal roller (porous roller or flat roller) arranged in the above can remove the solvent inside the color material by pushing it out. That is, it is possible to reliably remove the solvent on the intermediate transfer member while suppressing color material deviation.

  In addition, since the solvent inside the color material is pushed out after the color material is stabilized, the cohesive force of the color material is increased, the transfer rate to the recording medium is improved, and curling of the recording medium and image quality are improved. .

  The invention according to claim 2 is the ink jet recording apparatus according to claim 1, wherein the conveyance speed of the intermediate transfer body is 200 to 500 mm / s, and the pore diameter of the first porous body is 10 to 100 μm. It is characterized by being.

  A third aspect of the present invention is the ink jet recording apparatus according to the second aspect, wherein the first solvent removal roller is a solvent corresponding to 50 to 70% of the amount of ink applied to the intermediate transfer member. Solvent removal is performed so that the amount remains.

  A fourth aspect of the present invention is the ink jet recording apparatus according to any one of the first to third aspects, wherein the pore diameter of the first porous body is determined by ink droplets ejected from the recording head. It is 1/3 or more of the diameter of the dot formed by landing on the intermediate transfer member.

  In order to achieve the above object, the invention according to claim 5 provides a method invention. That is, according to the present invention, while the intermediate transfer member is conveyed, the ink and the treatment liquid containing a component that aggregates the coloring material in the ink are mixed and reacted on the intermediate transfer member, whereby the color is obtained. An ink jet recording method for aggregating materials to form an image on the intermediate transfer member, and transferring the image from the intermediate transfer member to a recording medium, the porous member having at least a surface composed of a first porous member A first solvent removing step of removing the solvent from the intermediate transfer member by contacting the surface of the intermediate transfer member while rotating the first solvent removing roller, which is a roller, and the transport direction of the intermediate transfer member A porous body roller disposed at the downstream side of the first solvent removal roller and having at least a surface made of a second porous body having a pore diameter or an aperture ratio smaller than that of the first porous body, or a hole is formed on the surface. Absent And a second solvent removal step of removing the solvent from the intermediate transfer member by contacting the surface of the intermediate transfer member while rotating the second solvent removal roller which is a surface roller. Inkjet recording method.

  According to the present invention, the first solvent removal roller (porous roller) disposed on the upstream side in the conveyance direction of the intermediate transfer body absorbs the solvent around the color material and stabilizes the color material, and then the downstream side. In addition to the residual solvent on the intermediate transfer member, the second solvent removal roller (porous roller or flat roller) arranged in the above can remove the solvent inside the color material by pushing it out. That is, it is possible to reliably remove the solvent on the intermediate transfer member while suppressing color material deviation.

  In addition, since the solvent inside the color material is pushed out after the color material is stabilized, the cohesive force of the color material is increased, the transfer rate to the recording medium is improved, and curling of the recording medium and image quality are improved. .

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

  In the ink jet recording apparatus according to the embodiment of the present invention, the ink and the processing liquid are mixed and reacted on the intermediate transfer member to aggregate the color materials contained in the ink and form an image (ink image) on the intermediate transfer member. This is an intermediate transfer type recording apparatus that forms and transfers an image from an intermediate transfer member to a recording medium.

  FIG. 1 is a schematic diagram showing the configuration of an ink jet recording apparatus according to an embodiment of the present invention. As shown in FIG. 1, the inkjet recording apparatus 10 of the present embodiment includes a processing liquid application unit 14 that applies a processing liquid to the intermediate transfer body 12, and a printing unit that performs ink ejection on the intermediate transfer body 12 (image formation). Part) 16, a solvent removing part 18 for removing the solvent on the intermediate transfer body 12, and an image transfer part 22 for transferring an image from the intermediate transfer body 12 to the recording medium 20.

  In this example, an ink containing a pigment or a dye as a color material (colorant) and a component that reacts with the ink to aggregate (undisperse or insolubilize) the color material (pigment or dye) contained in the ink. The processing liquid contained is used. In addition, since a well-known thing should just be used regarding an ink and a process liquid, it abbreviate | omits about detailed description.

  The intermediate transfer body 12 is composed of an endless belt member and has a structure wound around a plurality of rollers 24 (two rollers 24A and 24B in this example). At least a portion of the intermediate transfer body 12 facing the nozzle surface of the printing unit 16 is configured to form a horizontal surface (flat surface) as a region (image forming region) where ink ejected from the printing unit 16 lands.

  The power of the motor is transmitted to at least one of the plurality of rollers 24 (24A, 24B) around which the intermediate transfer body 12 is stretched, whereby the intermediate transfer body 12 is driven in the clockwise direction in FIG. Is done. The conveyance speed of the intermediate transfer body 12 is controlled by the conveyance control unit 50 shown in FIG.

  The entire intermediate transfer body 12 or at least a part of the surface (recording surface) including an image forming area on which ink ejected from the printing unit 16 lands is not penetrable by ink such as resin, metal, rubber, etc. (non-permeable) ).

  Preferred materials used for the surface of the intermediate transfer body 12 include, for example, a polyimide resin, a silicon resin, a polyurethane resin, a polyester resin, a polystyrene resin, a polyolefin resin, a polybutadiene resin, a polyamide resin, and a polychlorinated resin. Known materials such as vinyl resins, polyethylene resins, and fluorine resins can be used.

  The surface tension of the surface layer of the intermediate transfer body 12 is desirably 10 mN / m or more and 40 mN / m or less. If the surface tension is greater than 40 mN / m, there will be no difference in surface tension with the recording medium 20, and the transferability of the ink image (ink aggregate) will deteriorate. On the other hand, if the surface tension is less than 10 mN / m, considering the wettability of the treatment liquid, the surface tension of the treatment liquid needs to be smaller than the surface tension of the surface layer, and the surface tension of the treatment liquid is 10 mN / m or less. It is difficult to do, and the degree of freedom of design is narrowed.

  Further, it is desirable that the surface layer of the intermediate transfer body 12 has irregularities with a surface roughness (Ra) of about 0.3 μm, which has the effect of suppressing the movement of the color material.

  In the treatment liquid application unit 14, the treatment liquid is applied to the surface (recording surface) of the intermediate transfer body 12. In the present embodiment, the treatment liquid application unit 14 is provided with an application roller 26. The application roller 26 is rotated and brought into contact with the surface of the intermediate transfer body 12 to rotate the application roller 26 to the intermediate transfer body 12. A treatment liquid is applied to the surface. The treatment liquid is supplied to the surface of the application roller 26 by the treatment liquid supply means 28.

  The thickness (application thickness) of the treatment liquid applied to the intermediate transfer body 12 is preferably set in the range of 3 to 10 μm. This is because if the thickness of the treatment liquid applied by the application roller 26 is too thin, application unevenness occurs, whereas if the thickness is too large, the burden of removing the solvent increases. In particular, the thickness of the treatment liquid is preferably thicker than the thickness of the ink applied by the printing unit 16 on the downstream side in the conveyance direction of the intermediate transfer body 12. This is because when the treatment liquid is applied so as to be thinner than the thickness of the ink, an interface is formed between the ink droplet surface and the air layer, and droplet coalescence (landing interference) occurs due to surface tension.

  The application roller 26 is preferably a porous material or a material with irregularities on the surface, and for example, a gravure roll can be used.

  In the processing liquid application unit 14 of the present embodiment, the processing liquid is applied onto the intermediate transfer body 12 by applying the processing liquid using the application roller 26, but the present invention is particularly limited to this example. Instead, a method of applying a treatment liquid using a blade, a method of applying a treatment liquid using a spray or an inkjet head, and the like can be appropriately applied. In particular, when an inkjet head is used, the treatment liquid can be accurately applied in a pattern according to the recorded image.

  The printing unit 16 is disposed on the downstream side of the processing liquid application unit 14 with respect to the conveyance direction of the intermediate transfer body 12. After the processing liquid is applied on the intermediate transfer body 12 by the processing liquid application unit 14, the image data Ink is discharged based on the above. When the treatment liquid and the ink are mixed and reacted on the intermediate transfer body 12, the color materials in the ink aggregate and an image (ink image) composed of the color material aggregates (ink aggregates) is formed on the intermediate transfer body 12. The

  The printing unit 16 may be disposed on the upstream side of the treatment liquid application unit 14. In this case, application is performed on the intermediate transfer body 12 in the order of ink and processing liquid, and an ink image is formed on the intermediate transfer body 12 as described above.

  In the printing unit 16, an ink jet recording head (ink jet head) 30 is provided at a position facing the surface of the intermediate transfer body 12. The printing unit 16 may be provided with a plurality of recording heads 30. For example, recording heads corresponding to cyan (C), magenta (M), yellow (Y), and black (K) inks are sequentially arranged from the upstream side in the conveyance direction of the intermediate transfer body 12. Also good. Of course, the configuration is not limited to the standard color (four colors) of CMYK, and light ink, dark ink, and other color inks may be added as necessary. For example, it is possible to add a recording head that discharges light-colored ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

  The recording head 30 has a length corresponding to the maximum width of the image forming area of the intermediate transfer body 12 and is constituted by a full line type head in which a plurality of ink discharge ports (nozzles) are arranged over the entire width of the image forming area. The The recording head 30 is fixedly installed so as to extend in a direction orthogonal to the conveyance direction of the intermediate transfer body 12. An ink image can be formed on the intermediate transfer body 12 by ejecting ink from the recording head 30 while transporting the intermediate transfer body 12.

  In this way, according to the configuration in which the full line head having the nozzle row covering the entire width of the image forming area of the intermediate transfer body 12 is provided, the intermediate transfer body 12 and the recording head 30 are relative to each other in the transport direction of the intermediate transfer body 12. It is possible to record an image on the image forming area of the intermediate transfer body 12 only by performing the movement operation once (that is, by one sub-scan). High-speed printing is possible as compared with the case of using a serial type head that reciprocates in the direction (main scanning direction) orthogonal to the conveyance direction of the intermediate transfer body 12, and print productivity can be improved.

  In the present embodiment, as an example, a mode in which the printing unit 16 is configured with a full line head has been illustrated. However, the present invention is not particularly limited, and the printing unit 16 is configured with a serial head. Of course it is also good.

  As the ink ejection method of the recording head 30, a piezoelectric method that ejects ink by using the displacement of the piezoelectric element, a thermal method that ejects ink by using the thermal energy generated by the heating element, and other various methods are adopted as appropriate. Can do.

  An ink storage / loading unit (not shown) for storing ink to be supplied to the recording head 30 is provided with an ink tank. The ink tank communicates with the recording head 30 via a required flow path. The ink storage / loading unit includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors.

  The solvent removal unit 18 is disposed downstream of the printing unit 16 with respect to the conveyance direction of the intermediate transfer body 12. The solvent removal unit 18 is provided with a plurality of solvent removal rollers 32 along the conveyance direction of the intermediate transfer body 12. The solvent removal roller 32 is a porous roller having at least a surface made of a porous material. In the example shown in FIG. 1, solvent removal rollers 32 </ b> A and 32 </ b> B are sequentially arranged from the upstream side in the conveyance direction of the intermediate transfer body 12. The pore diameters of the porous bodies constituting each of the solvent removal rollers 32A and 32B are different from each other. Specifically, the solvent removal rollers (porous body rollers) on the downstream side are different from the solvent removal rollers (porous body) 32A on the upstream side. ) The pore size of the porous body of 32B is small. The solvent removing unit 18 removes the solvent on the intermediate transfer body 12 by sucking it into the porous body by contacting the surface of the intermediate transfer body 12 while rotating the solvent removal rollers 32 (32A, 32B). .

  In order to maintain the solvent absorption performance of the solvent removal roller (porous body roller) 32, it is preferable to provide a recovery mechanism for the solvent absorbed inside the porous body. For example, as shown in FIG. 2, there is a mode in which the solvent is collected in the collection container 42 by sucking the solvent inside the porous body from the surface side of the solvent removal roller 32 by the suction pump 40. In the illustrated example, the suction opening 44 that opens to the solvent removal roller 32 side is provided with a rubber-like contact portion 46 for the purpose of protecting the porous body, and the rubber-like contact portion 46 of the suction opening 44 is used as a solvent. By bringing the suction pump 40 into contact with the porous body of the removing roller 32 and sealing the inside of the suction opening 44, the solvent is efficiently recovered. The solvent recovery by the suction pump 40 is not performed while the solvent removal by the solvent removal roller 32 is being performed (that is, during the recording operation), and is performed in a state where the recording operation is paused or stopped.

  The solvent removal roller 32 (32A, 32B) is not limited to the above-described configuration, and the aperture ratio of the porous body of the downstream solvent removal roller 32B is smaller than that of the upstream solvent removal roller 32A. Also good. The solvent removal roller 32B on the downstream side may be a flat roller (aperture ratio 0%) in which no hole is formed on the surface. In the case where the downstream solvent removal roller 32B is configured by a flat roller, the solvent is removed from the intermediate transfer member 12 by attaching a solvent to the roller surface.

  In the solvent removal unit 18, the solvent on the intermediate transfer body 12 is removed by the solvent removal roller 32 (32 </ b> A, 32 </ b> B), so that a large amount of processing liquid is transferred onto the intermediate transfer body 12 in the upstream side processing liquid application unit 14. Even in such a case, a large amount of solvent (dispersion medium) is not transferred to the recording medium 20 by the image transfer unit 22 arranged on the downstream side of the solvent removal unit 18. Therefore, even when paper is used as the recording medium 20, problems characteristic to aqueous solvents such as curls and cockles do not occur.

  By removing the excess solvent from the ink aggregate by the solvent removing unit 18, the aggregate can be concentrated and the internal aggregating force can be further increased. Further, by concentrating the ink aggregates by removing the solvent, fixability and glossiness can be imparted to the image even after transfer to the recording medium 20.

  Note that it is not always necessary to remove all the solvent by the solvent removing unit 18. If the ink aggregate is excessively removed by excessive removal, the adhesion force of the ink aggregate to the intermediate transfer body 12 becomes too strong, and an excessive pressure is required for transfer, which is not preferable. Rather, in order to maintain viscoelasticity suitable for transferability, it is desirable to leave a small amount. As an effect obtained by leaving a small amount of the solvent, since the aggregate is hydrophobic and the solvent component that hardly volatilizes (mainly organic solvent such as glycerin) is hydrophilic, the ink aggregate and the residual solvent component are solvent. A thin liquid layer composed of residual solvent components is formed between the ink aggregate and the intermediate transfer body 12 after separation. Accordingly, the adhesive force of the ink aggregate to the intermediate transfer body 12 becomes weak, which is advantageous for improving transferability.

  The image transfer unit 22 is disposed downstream of the solvent removal unit 18 in the conveyance direction of the intermediate transfer body 12, and after the solvent is removed from the intermediate transfer body 12, an image from the intermediate transfer body 12 to the recording medium 20 is obtained. Transcription is performed.

  The image transfer unit 22 of this example has a structure in which one end (the lower end in FIG. 1) of an endless transport belt 34 that transports the recording medium 20 is wound around a transfer roller (nip roller) 36. The recording medium 20 transported to the intermediate transfer body 12 side by the transport belt 34 is pressurized at a predetermined pressure (nip pressure) to the intermediate transfer body 12 side by the transfer roller 36, and an ink image on the intermediate transfer body 12 is recorded. Transferred to the medium 20. After the image transfer, the recording medium 20 peeled from the intermediate transfer body 12 is transported to a discharge unit (not shown) by the transport belt 34.

  After the image transfer to the recording medium 20 is performed in the image transfer unit 22, a residue (for example, a coloring material) may remain on the surface of the intermediate transfer body 12 due to transfer failure or the like. If the above-described steps are repeatedly performed in the state where the residue remains on the intermediate transfer body 12, it causes deterioration in image quality. For this reason, it is preferable that a cleaning unit 52 for removing residues on the surface of the intermediate transfer body 12 is provided on the downstream side of the image transfer unit 22 in the conveyance direction of the intermediate transfer body 12. For example, there is an aspect in which a roller-like or belt-like cleaning member is brought into sliding contact with the surface of the intermediate transfer body 12 to remove the residue.

  Next, the solvent removal unit 18 which is a characteristic part of the present invention will be described in more detail.

  As described above, the solvent removing unit 18 of the present embodiment is provided with solvent removing rollers (porous rollers) 32A and 32B having at least a surface formed of a porous body in order along the conveyance direction of the intermediate transfer body 12. The pore diameter of the porous body of the downstream solvent removal roller 32B is smaller than that of the upstream solvent removal roller 32A.

  According to the study of the present inventor, when removing the solvent on the intermediate transfer member using only one solvent removal roller (porous roller) having a porous surface, the intermediate transfer member has a low speed (for example, , 50 mm / s), the solvent can be absorbed regardless of the pore size of the porous body, but when the intermediate transfer body is transported at a high speed (for example, 500 m / s). If the pore size of the porous material is small, the solvent is squeezed and color material deviation occurs. On the other hand, if the pore size of the porous material is large, the solvent remains on the intermediate transfer member, and the solvent is also left inside the color material. I understood that.

  Therefore, as a result of extensive investigations, the present inventor has found that in order to surely remove the solvent on the intermediate transfer member without causing color material displacement, a plurality of components are provided along the conveyance direction of the intermediate transfer member. It is effective to arrange a solvent removal roller (porous roller) and make the pore diameter of the porous body of the downstream solvent removal roller (porous roller) smaller than that of the upstream solvent removal roller (porous roller). I found out.

  Also, when the aperture ratio of the porous body of the downstream solvent removal roller (porous roller) is smaller than that of the upstream solvent removal roller (porous body roller), or when the downstream solvent removal roller is on the surface It has also been found that the same effect as described above can be obtained even in the case of a flat roller having no hole (opening ratio 0%).

  According to the configuration in which a plurality of solvent removal rollers are provided as described above, the upstream side solvent removal roller absorbs the solvent without squeezing the color material, and the downstream side solvent removal roller suppresses the color material displacement. The solvent can be removed while extruding the solvent inside.

  In order to confirm that the effects of the present invention can be obtained, an evaluation experiment was conducted on the solvent removal when the pore diameter of the porous body of the upstream solvent removal roller (porous roller) was changed (evaluation experiment). 1) An evaluation experiment was conducted on solvent removal when the pore diameter or opening ratio of the porous body of the downstream solvent removal roller (porous roller) was changed (Evaluation Experiment 2). Moreover, in the evaluation experiment 2, the evaluation experiment was also performed for the case where the downstream solvent removal roller was constituted by a flat roller.

  In these evaluation experiments 1 and 2, an evaluation apparatus having an apparatus configuration equivalent to that of the ink jet recording apparatus 10 of the present embodiment is used. The material of the porous body of the upstream solvent removal roller (porous roller) was silicon carbide, and the material of the porous body of the downstream solvent removal roller (porous roller) was polyethylene. Further, the pressure of each solvent removal roller against the intermediate transfer member was set to 0.1 MPa.

  In each of the evaluation experiments 1 and 2, in order to facilitate the measurement of the amount of solvent absorbed by the porous body of the solvent removal roller (absorption amount) and the amount of solvent remaining on the intermediate transfer member (residual amount), The absorption amount and the residual amount were measured by the method as described above. That is, first, a recording medium (non-penetrable medium; for example, OHP sheet) of a predetermined size is placed on the intermediate transfer member, and immediately after applying the treatment liquid and ink (before the upstream side solvent removal roller), the intermediate transfer is performed. After stopping the transport of the body, the OHP is taken out and the weight thereof is measured, whereby the total applied amount (film thickness) of the treatment liquid and the ink is converted from the weight. If the specific gravity of the treatment liquid or ink is 1, for example, if the weight is 0.03 g in OHP having a size of 30 × 100 mm, the film thickness is equivalent to 0.03 / 30/100 × 106 = 10 μm. Then, after reloading the OHP just before the upstream solvent removal roller, the intermediate transfer body is resumed, and the intermediate transfer body immediately after the upstream solvent removal roller and immediately after the downstream solvent removal roller, respectively. Is stopped, the weight of OHP is measured, and converted into a film thickness. For example, if the weight is 0.01 g, the film thickness is equivalent to 0.01 / 30/100 × 106 = 3.3 μm. The absorption amount at this time is 10−3.3 = 6.7 μm, and the remaining amount is determined to be 3.3 μm. By such a method, the absorption amount and residual amount of the solvent in each of the evaluation experiments 1 and 2 were measured.

[Evaluation Experiment 1]
In the evaluation experiment 1, first, as a basic condition, the total application amount (total film thickness) of the treatment liquid and ink is 15 μm (however, the application amount (film thickness) of the treatment liquid is 5 μm, and the application amount (film thickness) of the ink is 10 μm), the color material concentration in the ink is 5%, the dot diameter formed by the ink droplets deposited on the intermediate transfer body (actually OHP) is 30 μm, and the conveyance speed of the intermediate transfer body is 500 mm. The amount of solvent (absorption amount) absorbed by the porous body of the upstream solvent removal roller and the intermediate transfer body at that time while changing the pore diameter of the porous body of the upstream solvent removal roller while setting the conditions to / s (OHP) measures the amount of solvent remaining (residual amount), whether or not squeeze or color material misalignment occurs at the position where the upstream solvent removal roller is disposed, and further downstream process (downstream solvent Solvent removal with removal roller For the presence or absence of effects on and image transfer process, etc.) were evaluated. The evaluation results are shown in Table 1.

  As can be seen from Table 1, when the solvent is removed under the basic conditions, the pore diameter of the porous body of the upstream solvent removal roller is preferably in the range of 20 to 100 μm. At this time, the remaining amount of the solvent with respect to the ink application amount is 50 to 70%. In such a range, there is no influence on squeeze, color material deviation, and downstream processes.

  On the other hand, when the pore diameter of the porous body is 1 to 5 μm, solvent absorption by the porous body is not in time, and squeeze and color material deviation occur. In addition, when the pore size of the porous body is 10 μm, it is not squeezed, but the amount of solvent absorbed by the porous body is large, and color material deviation occurs.

  Further, when the pore size of the porous body is 200 μm, the residual amount of the solvent is too large, which adversely affects the downstream process. In such a situation, when the downstream solvent removing roller is a porous roller or a flat roller having a smaller hole diameter than the upstream solvent removing roller, the solvent is absorbed (or adhered) on the downstream side. Without this, squeeze and color material deviation occur. Further, when the solvent removal roller on the downstream side is a porous roller having a relatively large hole diameter, even if squeezing does not occur, the residual amount of the solvent on the intermediate transfer member increases, and in this state the recording medium When image transfer to is performed, there is an adverse effect that the transfer rate is lowered by the residual solvent.

  Next, in order to confirm the relationship with the conveyance speed of the intermediate transfer member, an evaluation experiment similar to Table 1 was performed by changing the conveyance speed of the intermediate transfer member among the basic conditions. Table 2 shows the evaluation results when the conveyance speed of the intermediate transfer member is 200 mm / s, and Table 3 shows the evaluation results when the conveyance speed is 50 mm / s.

  As can be seen from Tables 1 to 3, as the conveyance speed of the intermediate transfer member decreases, squeeze and color material displacement do not occur, and the pore diameter of the porous member that does not affect downstream processes becomes wider. In particular, when the conveyance speed of the intermediate transfer member is 50 mm / s, the pore diameter of the porous member of the upstream solvent removal roller is preferably in the range of 5 to 200 μm. When the intermediate transfer member is conveyed at low speed, the solvent can be absorbed without squeezing even if the pore size of the porous member is small. In addition, even if the pore diameter of the porous body is large, it is possible to absorb the solvent located in the portion where the pore does not exist if the transport speed is low.

  As is clear from Tables 1 and 2, it was found that similar evaluation results can be obtained when the conveyance speed of the intermediate transfer member is in the range of 200 to 500 mm / s.

  Next, in order to confirm the relationship between the total application amount (total film thickness) of the treatment liquid and ink to the intermediate transfer member, the application amount (film thickness) of the treatment liquid or ink is changed among the basic conditions. Evaluation experiment similar to 1 was performed. Table 4 shows the evaluation results when the application amount of the treatment liquid is 10 μm and the total application amount of the treatment liquid and ink is 20 μm.

  Table 5 shows the evaluation results when the applied amount of ink is 20 μm and the total applied amount of treatment liquid and ink is 25 μm. The applied amount of ink is 5 μm and the total applied amount of treated liquid and ink is 10 μm. Table 6 shows the evaluation results when

  As can be seen from Tables 1 and 4, even when the amount of treatment liquid applied is large, there is no difference in the residual amount of solvent when the pore size of the porous body is large. This can be said that there is still room for the solvent absorption capacity.

  On the other hand, as can be seen from Tables 1, 5, and 6, as the applied amount of ink increases, the residual amount of solvent tends to increase. Conversely, when the applied amount of ink decreases, the residual amount of solvent decreases. This is considered that the residual solvent increases due to the influence of the ink that has reacted with the treatment liquid.

  Next, in order to confirm the relationship with the color material concentration in the ink, the same evaluation experiment as in Table 1 was performed by changing the color material concentration in the ink among the basic conditions. Table 7 shows the evaluation results when the color material concentration in the ink is 2.5%, and Table 8 shows the evaluation results when the color material concentration is 10%.

  As can be seen from Tables 1, 7, and 8, the remaining amount of the solvent does not change regardless of the color material concentration in the ink. This can be presumed to be because the dot diameter is almost the same regardless of the color material concentration in the ink, and the factor that inhibits solvent absorption depends on the size of the two-liquid reacted dot.

  Next, in order to confirm the relationship with the dot diameter, the same evaluation experiment as in Table 1 was performed by changing the dot diameter among the basic conditions. Table 9 shows the evaluation results when the dot diameter is 60 μm.

  As can be seen from Tables 1 and 9, when the dot diameter increases, color material misalignment occurs when the pore diameter of the porous body is small. This is presumably because when the dots completely block the pores of the porous body, the capillary force increases the pulling force of the color material, and color material displacement occurs. In addition, when the hole of the porous body is not completely blocked with dots, an excessive force is not applied to the color material because the solvent and air are sucked.

  From the above, it is assumed that the pore diameter of the porous body of the upstream solvent removal roller (porous roller) is 20 to 100 μm (preferably the dot diameter or more), the conveyance speed of the intermediate transfer member is 200 to 500 mm / s, It has been found that it is effective to remove the solvent so that 30 to 47% of the total applied amount of ink (corresponding to 50 to 70% of the applied amount of ink) remains.

[Evaluation Experiment 2]
In the evaluation experiment 2, as the downstream solvent removal roller, an evaluation experiment 1 was performed using a porous roller or a flat roller having a pore diameter and an opening ratio different from those of the upstream solvent removal roller (porous roller). The same conditions as in the above were set, and the presence or absence of an influence on squeeze, color material deviation, and downstream process (image transfer process, etc.) at the position where the downstream solvent removal roller is arranged was evaluated. The evaluation results are shown in Table 10. The table also shows the conditions and evaluation results of the upstream solvent removal roller used at this time.

  As can be seen from Table 10, as the downstream solvent removal roller, a porous roller having a larger pore diameter than that of the upstream solvent removal roller (porous roller) is used. More solvent can be removed than when using. Further, even when a porous roller having a smaller aperture ratio of the porous body than that of the upstream solvent removal roller (porous roller) or when using a flat roller having a larger number of flat portions, a large amount of solvent can be removed. And the remaining amount of the solvent on the intermediate transfer member can be reduced.

  According to an aspect in which a porous roller or a flat roller having a smaller aperture ratio (that is, having a larger number of flat portions) than the upstream solvent removing roller is used as the downstream solvent removing roller, the color material on the intermediate transfer member is crushed. In addition to extruding the solvent inside the color material, the cohesive force of the color material increases as a result of the solvent being extruded, and the color material is transferred without crying when transferring the color material to the recording medium. Can be improved.

  On the other hand, if the solvent inside the color material is not removed and the transfer is performed with the solvent inside the color material, the scratches may be reduced due to the effect of the solvent while remaining inside the color material. This solvent moves to the recording medium, and the recording medium curls.

  Further, in order to suppress the height of the color material, it is effective to crush the color material with a flat roller before the transfer. If the color material is transferred without being crushed, it may not be able to be properly suppressed at the time of transfer due to the unevenness of the recording medium. If a raised color material is present, the quality of the image deteriorates. In this way, crushing the color material at the stage before transfer has various effects.

  In addition, in the portion where there is no color material, a slight amount of the solvent remaining on the intermediate transfer member remains, and in order to remove the solvent, the solvent is not applied to the surface of the solvent removal roller. It is better to use the physical phenomenon of attaching and removing. This is because a solvent sandwiched between planes of similar surface energy separates at about 50:50. However, if there are pores in the porous body, the solvent cannot adhere to those parts, but all of them are flat. This is because approximately half of the solvent can be removed. Therefore, where there is little residual solvent, using a flat roller can remove the solvent more than a porous body that relies on absorption.

  Also, if the porous body has a smaller pore diameter than the upstream side, it will be pulled with a stronger capillary force against the slight amount of solvent that could not be removed by the upstream side porous roller, so that the solvent is absorbed more in the same way. Can be removed.

  Next, FIG. 3 shows an arrangement configuration example of the solvent removal roller to which the present invention is applied.

  FIG. 3A shows a configuration similar to that of the solvent removing unit 18 of the ink jet recording apparatus 10 shown in FIG. 1, and is along the transport direction of the intermediate transfer member (the direction indicated by the arrow in the figure). Two solvent removal rollers 60 and 62 are sequentially arranged from the upstream side. Each of the solvent removal rollers 60 and 62 is a porous roller having at least a surface formed of a porous body, and is a porous body of a solvent removal roller (porous body roller) downstream from the upstream solvent removal roller (porous body roller) 60. The hole diameter is small. Moreover, the opening ratio of the porous body of the solvent removal roller (porous body roller) on the downstream side of the upstream solvent removal roller (porous body roller) 60 may be configured to be small.

  FIG. 3B shows a solvent removal roller (planar roller) 64 having no hole at the surface in place of the solvent removal roller (porous roller) 62 on the downstream side shown in FIG. It is the example of arrangement | positioning. As described above, the solvent removal roller (porous roller) 60 on the upstream side sucks and removes the solvent on the intermediate transfer body while suppressing color material displacement without squeezing, and then the solvent removal roller on the downstream side. While the solvent in the color material is pushed out by the (flat roller) 64, the solvent can be attached to the surface of the flat roller for removal. Thereby, effects such as improvement in transfer rate, prevention of curling of the recording medium, and improvement in image quality can also be obtained.

  FIG. 3C shows a configuration example in which a solvent removal roller (planar roller) 64 is arranged on the downstream side of the solvent removal roller (porous roller) 62 shown in FIG. FIG. 3D shows a configuration example in which a solvent removal roller (porous roller) 62 is arranged on the downstream side of the solvent removal roller (planar roller) 64 shown in FIG. According to the aspect in which the solvent removal roller (porous roller) 62 and the solvent removal roller (planar roller) 64 are arranged on the downstream side of the solvent removal roller (porous roller) 60, either one of the solvent removal rollers 62, 64 is provided. Solvent inside the coloring material, which is difficult to remove by itself, can be reliably removed by the capillary force of the porous body and the crushing effect of the coloring material by the flat roller. In addition, effects such as improvement in transfer rate, prevention of curling of the recording medium, and improvement in image quality can be obtained.

  In the practice of the present invention, the arrangement order of the solvent removal rollers 62 and 64 arranged on the downstream side of the solvent removal roller 60 is not particularly limited, but the effect (color) of crushing the color material as described above From the viewpoint of improvement in material cohesive force, scratchability, curl, and color material height), the configuration example shown in FIG.

  Further, the number of solvent removal rollers arranged on the downstream side of the solvent removal roller 60 is not limited to the configuration example shown in FIGS. 3C and 3D, and more solvent removal rollers are provided in the middle. Of course, the solvent may be removed stepwise by these solvent removal rollers which are sequentially arranged along the transfer direction of the transfer body.

  FIG. 3E shows a configuration example in which a plurality (two in this example) of solvent removal rollers 60 are arranged upstream of the solvent removal roller (porous roller) 62 shown in FIG. FIG. 3F shows a configuration example in which a plurality of (two in this example) solvent removal rollers 60 are arranged upstream of the solvent removal roller (planar roller) 64 shown in FIG. 3B. . In this way, the upstream side may also be removed by absorbing the solvent in a stepwise manner using a plurality of solvent removal rollers 60.

  Next, FIG. 4 shows an arrangement configuration example (comparative example) of the solvent removal roller when the present invention is not applied.

  FIG. 4A shows a configuration example in which the solvent removal roller (porous roller) 60 shown in FIG. In this case, since the pore diameter of the porous body is large, the solvent cannot be sufficiently absorbed and removed.

  FIG. 4B is a configuration example in which the solvent removal roller (porous roller) 62 shown in FIG. In this case, since the pore diameter of the porous body is small, the absorption rate of the solvent is slow and the capillary force is strong.

  FIG. 4C is a configuration example in which a plurality of solvent removal rollers (porous rollers) 60 are arranged. In this case, there is a problem similar to the configuration example shown in FIG.

  FIG. 4D is a configuration example in which a plurality of solvent removal rollers (porous rollers) 62 are arranged. In this case, there is a problem similar to the configuration example shown in FIG.

  FIG. 4E shows a configuration example in which the solvent removal roller (planar roller) 64 shown in FIG. In this case, there is a problem that the color material is squeezed.

  As described above, a plurality of solvent removal rollers are sequentially arranged along the conveyance direction of the intermediate transfer member, and the solvent removal roller (porous roller) on the downstream side from the solvent removal roller (porous roller) on the upstream side is arranged. However, if the pore size or aperture ratio of the porous body is small, or the downstream solvent removal roller is constituted by a flat roller, the upstream side solvent removal roller (porous body roller) does not squeeze the color material deviation. The remaining solvent can be reliably removed by sucking and removing the solvent on the intermediate transfer member while suppressing it and then extruding the solvent in the coloring material with the downstream solvent removing roller (porous roller or flat roller). it can.

  Although the ink jet recording apparatus and the recording method of the present invention have been described in detail above, the present invention is not limited to the above examples, and various improvements and modifications can be made without departing from the spirit of the present invention. Of course it is good.

Schematic showing the configuration of the inkjet recording apparatus Partial enlarged view of solvent removal section The figure which showed the example of arrangement | positioning structure of the solvent removal roller in case this invention is applied The figure which showed the example of arrangement | positioning structure of the solvent removal roller in case this invention is not applied

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 12 ... Intermediate transfer body, 14 ... Processing liquid application part, 16 ... Printing part, 18 ... Solvent removal part, 20 ... Recording medium, 22 ... Image transfer part, 26 ... Application roller, 30 ... Recording head, 32 (32A, 32B) ... Solvent removal roller, 36 ... Transfer roller, 50 ... Conveyance control unit

Claims (5)

While the intermediate transfer body is being conveyed, the color material is agglomerated by mixing and reacting the ink and the treatment liquid containing a component that agglomerates the color material in the ink on the intermediate transfer body. An inkjet recording apparatus that forms an image on a body and performs image transfer from the intermediate transfer body to a recording medium,
A treatment liquid application unit for applying the treatment liquid onto the intermediate transfer member;
An image forming unit that ejects ink from an inkjet recording head to the intermediate transfer member;
At least two solvent removal rollers are sequentially arranged along the conveyance direction of the intermediate transfer member, and the solvent removal roller is rotated and brought into contact with the surface of the intermediate transfer member to remove the solvent from the intermediate transfer member. A solvent removal unit to perform,
An image transfer unit that transfers an image formed on the intermediate transfer member to the recording medium,
The first solvent removal roller disposed on the upstream side with respect to the conveyance direction of the intermediate transfer body is a porous body roller having at least a surface formed of the first porous body, and the second solvent removal roller disposed on the downstream side is at least A porous roller having a surface made of a second porous body, or a flat roller having no hole formed on the surface;
An ink jet recording apparatus, wherein the second porous body has a smaller pore diameter or aperture ratio than the first porous body. The conveyance speed of the intermediate transfer member is 200 to 500 mm / s,
The inkjet recording apparatus according to claim 1, wherein the pore diameter of the first porous body is 10 to 100 μm.   The inkjet according to claim 2, wherein the first solvent removing roller removes the solvent so that a solvent amount corresponding to 50 to 70% of an ink amount applied on the intermediate transfer member remains. Recording device.   The hole diameter of the first porous body is 1/3 or more of a diameter of a dot formed by landing an ink droplet ejected from the recording head on the intermediate transfer body. The ink jet recording apparatus according to claim 3. While the intermediate transfer body is being conveyed, the color material is agglomerated by mixing and reacting the ink and the treatment liquid containing a component that agglomerates the color material in the ink on the intermediate transfer body. An inkjet recording method for forming an image on a body and transferring an image from the intermediate transfer body to a recording medium,
A first solvent removing roller from the intermediate transfer member is brought into contact with the surface of the intermediate transfer member while rotating a first solvent removing roller which is a porous roller having at least a surface formed of the first porous member. A solvent removal step;
A porous roller that is disposed downstream of the first solvent removal roller in the transport direction of the intermediate transfer body, and at least a surface of which is composed of a second porous body having a pore diameter or an aperture ratio smaller than that of the first porous body, or A second solvent removal step of removing the solvent from the intermediate transfer member by rotating the second solvent removal roller, which is a flat roller having no hole on the surface, while contacting the surface of the intermediate transfer member When,
An ink jet recording method comprising:

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