JP2010188568A - Pretreatment apparatus of recording medium and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve set-off which is a problem occurring when image quality is improved by an image quality improvement treating solution, without using a means requiring much energy such as a heater. <P>SOLUTION: In an image forming apparatus, an ink composition containing at least a color material is ejected by using an inkjet recording means to form an image on a recording medium (42). Further the image forming apparatus has a first processing section (70) for promoting water absorptivity of the recording medium and a second processing section (80) for imparting the image quality improvement treating solution containing a coagulant for coagulating the ink composition to the recording medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an ink jet system such as a copying machine or a printer, and more particularly relates to a preprocessing apparatus for a recording medium (recording material) in the image forming apparatus, and an image forming apparatus provided with the same. Therefore, it can be applied to a copying machine, a facsimile, a printer, and the like using an ink jet system.

  Inkjet recording technology is a technology that uses a pressurized on-demand method, a charge control method, etc. to form ink droplets through micro nozzles and attach them to recording media such as paper according to image information. Printers, facsimiles, and copying It is suitably used for an image forming apparatus such as a printer. Since such an ink jet recording technique can form an image by directly attaching ink to a recording medium, it can be recorded with a simple apparatus configuration compared to indirect recording using a photoconductor such as electrophotographic recording. Further development is expected as an image recording method for recording media.

Here, the ink jet recording technique will be described with reference to FIG.
As shown in FIG. 12 (a), an ink jet ink droplet 163 in which a coloring material 162 made of pigment or dye is dispersed in a vehicle 161 mainly composed of water is used, and the ink droplet is made by an ink jet head. As shown in FIG. 12 (b), the vehicle 161 and the color material 162 are formed on the pulp fibers of the paper as shown in FIG. 12 (b) when the 163 is caused to fly and adhere to a recording medium 164 such as high-quality paper or rough paper. Along the inside of the paper. For this reason, since ink flows along the pulp fibers on the paper surface, a lateral flow such as jaggy occurs in ink dots called feathering.
In addition, when a first color ink droplet layer is formed on paper as in a color image and the second color ink droplet is attached before the first color is dried on the paper, the shape of the second color ink dot is disturbed. Ink flows on the paper surface, causing dot bleeding called color bleeding.

Furthermore, since most of the color material 162 penetrates into the paper, a decrease in image density and an increase in density on the back side of the paper (this is referred to as image back-through) occur. When the ink droplet 163 comes into contact with another ink droplet before penetrating the inside of the paper on the paper surface, the ink droplets coalesce to form a dot larger than a desired dot diameter called beading. As a result, a noticeable graininess may occur.
That is, ink penetrates to the back side of the recording medium due to ink droplets adhering to the recording medium 164 such as paper or resin film, and in continuous printing, ink is deposited on the back surface of the recording medium due to the overlapping of the recording media 164. Adhering set-off, feathering, beading, color bleeding, and mottling, which is uneven density of ink droplets on the recording medium 164, occur.

  Therefore, conventionally, Japanese Unexamined Patent Application Publication No. 2006-205465 ("Processing Liquid, Ink Set, Recorded Material, Recording Method, Ink Tank, and Recording Apparatus", Japanese Patent Application Laid-Open No. 2001-301138 ("Recording"). As described in “Recording method and apparatus for printing using two liquids on medium”, Patent Document 2), or Japanese Patent Application Laid-Open No. 64-9279 (“Inkjet recording method”, Patent Document 3). Immediately before the ink droplets adhere to the high-quality paper or rough paper, an ink processing liquid having a function of fixing ink, that is, an image quality improving processing liquid is applied to prevent feathering and color bleeding.

Hereinafter, the conventional technique will be described in detail with reference to FIG.
When high-quality paper or a resin film is used as the recording medium 164, an ink droplet 163 is attached as shown in FIG. 13A in order to form a high-quality image on the recording medium by the flying of the ink droplet 163. Before this, a liquid for fixing the ink coloring material 162 in advance, a so-called image quality improvement processing liquid 165 is formed on the surface of the recording medium 164. Then, as shown in FIG. 13B, when the ink droplet 163 is attached to the image quality improvement processing liquid layer, the color material 162 in the ink aggregates and adheres as shown in FIG. 13C. The pulp fibers cannot pass and the color material 162 stops on the paper surface. On the other hand, since the vehicle 161 penetrates into the paper, it is possible to prevent feathering, color bleeding, image density reduction, and image see-through. The same applies to the case where the recording medium is a resin film. Although the vehicle 161 stops on the film surface, the color material 162 is agglomerated but cannot move, and beading can be prevented.

  In order to agglomerate the color material 162 in the ink as described above, first, the color material 162 in the ink needs to be charged negatively or positively. The dye is ionized positively or negatively in water by itself. In the case of a pigment, in a self-dispersing pigment, the pigment itself is ionized positively or negatively in water. When a pigment dispersant is used, the dispersant adsorbs to the pigment in water and ionizes positively or negatively, and as a result, the pigment itself ionizes positively or negatively. Generally, the color material 162 is negatively ionic and dispersed in the ink.

As shown in FIG. 14 (a), the first principle of the image quality improvement process is that the ink in which the color material 162 is negatively ionized in water is dispersed in water as shown in FIG. 14 (b). When contacted with an image quality improvement processing solution that is acidic and contains a large amount of protons (positive charge), as shown in FIG. 14C, a large amount of protons in the image quality improvement processing solution are negatively ionic. The principle is that they are electrostatically coupled to each other and these coloring materials are aggregated.
As shown in FIG. 15A, the second principle of the image quality improvement processing is that the ink in which the color material 162 is negatively ionized in water is dispersed in water as shown in FIG. 15B. When contacted with the image quality improvement processing liquid containing a positively charged cationic member, as shown in FIG. 15C, the negative colorant 162 is negatively charged between the cationic members in the image quality improvement processing liquid. The principle is that these color materials are aggregated by electrical coupling.
Further, as shown in FIG. 16A, the third principle of the image quality improvement processing is that the ink in which the color material 162 is negatively ionized in water is dispersed as shown in FIG. When contacted with the image quality improvement processing liquid containing metal ions having a positive charge in water, as shown in FIG. 16C, the color materials 162 having negative ionicity to the metal ions in the image quality improvement processing liquid are statically exchanged. The principle is that these color materials are aggregated by electrical coupling.

By aggregating the color material 162 in the ink with the image quality improving treatment liquid as described above, a great effect can be obtained for show-through, feathering, beading, and color bleeding. On the other hand, the reverse of the ink that adheres to the back surface of the recording medium due to the overlap between the media is lowered and the effect cannot be obtained. This is considered to be because the color material 162 aggregated by the image quality improvement processing liquid forms a film on the surface of the paper, thereby inhibiting the ink vehicle component from being absorbed by the paper. Such a phenomenon is particularly noticeable for paper with poor water absorption, in which a large amount of sizing agent is used. In a high-speed image forming apparatus, a step of drying with a heater or the like is required to prevent this. ing.
Inkjet recording technology has a significant advantage in terms of energy consumption compared to an electrophotographic method in which toner is melted by heat and fixed on paper, but a heater is used to dry the ink. If used, its superiority is impaired.

  Therefore, the technical problem of the present invention is that, in order to solve the above-described conventional problems in an inkjet image forming apparatus, a back-off that becomes a problem when image quality is improved by an image quality improvement processing liquid It is to devise so that it can be improved without using means that require a great deal of energy.

Below, the means taken in order to solve the above problems will be described together with the action.
(1) An image forming apparatus according to the present invention (corresponding to claim 1) is premised on an image forming apparatus that forms an image on a recording medium by ejecting an ink composition containing at least a colorant using an ink jet recording unit. As
A first processing unit that promotes water absorption of the recording medium; and a second processing unit that applies an image quality improvement processing liquid containing an aggregating agent that aggregates the ink composition to the recording medium.

  With this configuration, the water absorption promotion process for the recording medium is performed in the first processing unit, and the image quality improvement process is performed on the recording medium in the second processing unit. Therefore, when an image is formed by the inkjet recording unit In addition, it is possible to obtain a high-quality image by preventing ink bleeding. Further, it is possible to promote the permeation and drying of the ink into the recording medium, and it is possible to prevent the set-off from occurring even when the transfer paper has poor absorbability or during high-speed printing.

(2) In the image forming apparatus of (1), the first processing unit can be arranged upstream of the second processing unit in the recording medium conveyance path. (Corresponding to claim 2)
With such a configuration, after the water absorption promotion process is performed in the first processing unit, the image quality improvement process is performed in the second processing unit. Therefore, if the ink contacts the surface of the recording medium during image formation, The condensing agent in the ink aggregates the coloring material in the ink. This condensation reaction occurs immediately on the surface of the recording medium, and aggregation occurs before the ink starts to penetrate into the recording medium. The effect of improving image quality is increased.

(3) In the image forming apparatus according to (1) or (2), the first processing unit may be configured by a processing liquid applying apparatus that applies a hydrophilic treatment liquid. (Corresponding to claim 3)
With such a configuration, since the hydrophilic treatment liquid is applied to the recording medium in the first processing unit, it is possible to obtain a high-quality image by preventing ink bleeding and to penetrate and dry the ink on the recording medium. It is possible to prevent the set-off from occurring even during transfer paper with poor absorbability or high-speed printing.
In addition, by applying a hydrophilic treatment liquid to the water absorption promotion process in the first processing unit, the pigment component in the ink is aggregated by applying the image quality improvement processing liquid in the second processing unit. It becomes possible to prevent the set-off due to the deterioration of the drying property.

(4) In the image forming apparatus according to (1) or (2), the first processing unit may be constituted by one of a plasma irradiation device, a corona discharge device, and a charging roller device. (Corresponding to claim 4)
With such a configuration, in the first processing unit, the water absorption of the recording medium is promoted by one of the plasma irradiation device, the corona discharge device, and the charging roller device, whereby the image forming apparatus according to (3) above. Produces the same effect.
In addition, if the water absorption promotion process in the first processing unit is performed by the plasma irradiation apparatus, it is possible to perform the process by a non-contact means without using the liquid, and thus problems such as liquid supply and liquid spillage. There is no need to consider. However, the device is relatively complex and large. Therefore, if it is performed by a corona discharge device, it cannot be performed as strong as a plasma irradiation device, but it can be performed by a simple device while being non-contact. Similar to the discharge device, it is possible to perform the hydrophilic treatment by a relatively simple mechanism.

(5) In the image forming apparatus according to any one of (1) to (4), the first processing unit may include an adjusting unit that adjusts the degree of processing for promoting water absorption of the recording medium. Good. (Corresponding to claim 5)
With such a configuration, it is possible to perform water absorption promotion processing in consideration of the water absorption characteristics of a recording medium such as paper, and it is possible to prevent unnecessary processing such as applying a hydrophilic treatment liquid more than necessary. it can.

(6) The image forming apparatus according to any one of (1) to (5) may further include a switching unit that switches presence / absence of processing in the second processing unit. (Corresponding to claim 6)
With such a configuration, it is possible to perform image quality improvement processing in consideration of characteristics of a recording medium such as paper, and it is possible to prevent application of useless processing liquid.

(7) In the image forming apparatus according to any one of the above (1) to (6), the flocculant contained in the image quality improvement processing liquid applied by the second processing unit includes a polyvalent metal salt, an organic acid, and It may be one or more selected from polyamines. (Corresponding to claim 7)
With such a configuration, the flocculant contained in the image quality improvement processing liquid contains one or more compounds selected from polyvalent metal salts, organic acids, and polyamines. The dispersed state of the material components can be made unstable and aggregated, and the aggregated color material components are less likely to permeate the interior of the transfer paper and along the fibers, so that image bleeding can be prevented.

(8) The image forming method according to the present invention (corresponding to claim 8) is premised on an image forming method in which an ink composition containing at least a coloring material is ejected by using an ink jet recording means to form an image on a recording medium. As
In the first processing unit that promotes the water absorption of the recording medium, after promoting the water absorption of the surface of the recording medium, an image quality improving treatment liquid is applied in the second processing unit, and then the ink composition according to the image data An image is formed by ejecting an object.

With this configuration, after performing the water absorption promotion process of the recording medium in the first processing unit, the image processing process is performed on the recording medium in the second processing unit, and then an image is formed using the ink composition. Therefore, it is possible not only to prevent ink bleeding but to obtain a high-quality image, but also to promote the penetration and drying of the ink into the recording medium. It is possible to prevent set-off.
In addition, when the ink contacts the surface of the recording medium during image formation, the coloring material in the ink immediately aggregates. Therefore, aggregation occurs before the ink starts to penetrate into the recording medium, and prevention of bleeding due to promotion of ink permeation drying. Degradation of function can be suppressed as much as possible. Accordingly, the effect of suppressing bleeding is strong, and it is possible to sufficiently prevent bleeding with a small amount of image quality improvement processing liquid, and the effect of improving the image quality is great.

(9) In the image forming method of (8), the degree of processing by the first processing unit that promotes water absorption of the recording medium may be adjusted by information input according to the type of the recording medium. it can. (Corresponding to claim 9)
With such a configuration, water absorption promotion treatment can be performed in consideration of the water absorption characteristics of a recording medium such as paper, and therefore it is possible to prevent wasteful treatment such as applying a hydrophilic treatment liquid more than necessary. It is.

(10) Further, in the image forming method of (8), only when the image quality improvement processing liquid is applied in the second processing unit, the water absorption promotion processing is performed in the first processing unit, and the image quality improvement processing is performed. When the liquid is not applied, the hydrophilic treatment may not be performed. (Corresponding to claim 10)
With such a configuration, processing can be performed in consideration of water absorption characteristics of a recording medium such as paper and agglomeration characteristics for aggregating the ink composition, so that a hydrophilic treatment liquid or an image quality improvement treatment liquid is wasted. Unnecessary processing can be prevented.

(11) A recording medium pretreatment apparatus according to the present invention (corresponding to claim 11) is a method in which an ink composition containing at least a colorant is ejected using an ink jet recording means to form an image on a recording medium. And a pre-processing device for processing the recording medium,
A first processing unit that promotes water absorption of the recording medium; and a second processing unit that applies an image quality improvement processing liquid containing an aggregating agent that aggregates the ink composition to the recording medium.

  With this configuration, the first processing unit in the recording medium pre-processing apparatus performs the water absorption promotion processing of the recording medium and the second processing unit performs the image quality improvement processing on the recording medium. When an image is formed on a recording medium by ink jet recording means, it is possible to prevent ink bleeding and obtain a high quality image. Further, it is possible to promote the permeation and drying of the ink into the recording medium, and it is possible to prevent the set-off from occurring even when the transfer paper has poor absorbability or during high-speed printing.

The effects of the present invention are summarized as follows.
Since the first processing unit performs water absorption promotion processing of the recording medium and the second processing unit performs image quality improvement processing, it is possible to prevent ink bleeding and obtain a high-quality image. Further, it is possible to promote the permeation and drying of the ink into the recording medium, and it is possible to prevent the set-off from occurring even when the transfer paper has poor absorbability or during high-speed printing.
Furthermore, after the water absorption promotion treatment is performed in the first processing section, the image quality improvement processing is performed in the second processing section, so that when the ink contacts the surface of the recording medium during image formation, the color material in the ink is immediately aggregated. Therefore, aggregation occurs before the ink begins to penetrate into the inside of the recording medium. As a result, it is possible to obtain an image with higher image quality, with the bleeding suppressed strongly.
Since processing can be performed in consideration of the characteristics of the recording medium, useless processing can be prevented.

FIG. 3 is a perspective view of the image forming apparatus viewed from the front side. FIG. 3 is a schematic configuration diagram of a mechanism unit of the image forming apparatus as viewed from above. FIG. 3 is a schematic configuration diagram of a mechanism unit of the image forming apparatus viewed from the side. FIG. 3 is an enlarged plan view of a recording head unit. FIG. 3 is an enlarged front view of a recording head unit. FIG. 4 is an explanatory diagram of components constituting the recording head, in which (a) is an enlarged view of a main part of the tip, (b) is an enlarged side view, and (c) is an enlarged plan view. These are the schematic diagrams explaining the structure of the 1st process part which promotes the water absorption of a recording medium, and the 2nd process part which provides an image quality improvement process liquid. FIG. 4 is a schematic diagram illustrating the configuration of a first processing unit that promotes water absorption of a recording medium and a second processing unit that applies an image quality improvement processing liquid, and the first processing unit includes a plasma irradiation apparatus. Show the case. These are the schematic diagrams explaining the structure of the 1st process part which promotes the water absorption of a recording medium, and the 2nd process part which provides an image quality improvement process liquid, and a 1st process part consists of a corona discharge device. Show the case. FIG. 4 is a schematic diagram illustrating the configuration of a first processing unit that promotes water absorption of a recording medium and a second processing unit that applies an image quality improvement processing liquid, and the first processing unit includes a charging roller device. Show the case. These show the result of having measured the water absorption of various recording media (transfer paper) with the JIS P 8122 paper's Steech human size test method. These are the schematic diagrams of the pressure adjustment mechanism between rollers which controls the application amount of a process liquid. These are the schematic diagrams explaining the structure of the path | route switching means which switches the conveyance path to a 1st process part and a 2nd process part. FIG. 4 is a schematic diagram for explaining an ink jet recording technique, where (a) shows a state in which ink droplets fly and adhere to a recording medium (paper), and (b) shows a vehicle or color material in the ink being a recording medium. Shows penetration into the interior. FIG. 4 is a schematic diagram for explaining a conventional ink jet recording technique, in which (a) shows a recording medium (paper) formed with an image quality improving treatment liquid on the surface, and (b) shows an image quality improving treatment liquid layer on the surface of the recording medium. (C) shows a state in which the color material in the ink is aggregated and fixed on the surface of the recording medium, and the vehicle penetrates into the recording medium. FIG. 4 is a schematic diagram for explaining the first principle of image quality improvement processing, where (a) shows ink in which a coloring material is negatively ionized and dispersed in water, and (b) shows acidity in water and a large amount. The image quality improvement processing liquid containing protons (positive charge) is shown. (C) shows a state where the negatively ionic coloring materials are electrostatically bonded to and aggregated with a large amount of protons in the image quality improvement processing liquid. Show. FIG. 4 is a schematic diagram for explaining a second principle of image quality improvement processing, where (a) shows an ink in which a coloring material is negatively ionized and dispersed in water, and (b) shows a cation having a positive charge in water. FIG. 4C shows a state in which negative ionic coloring materials are electrostatically bonded to and aggregated with the cationic member in the image quality improvement processing liquid. FIG. 4 is a schematic diagram for explaining a third principle of image quality improvement processing, where (a) shows an ink in which a coloring material is negatively ionized and dispersed in water, and (b) shows a metal having a positive charge in water. An image quality improvement treatment liquid containing ions is shown, and (c) shows a state in which color materials having negative ionic properties are electrostatically bonded to and aggregated with metal ions in the image quality improvement treatment liquid.

  The present invention achieves the object of improving the set-off of the ink adhering to the back surface of the recording medium without requiring a large amount of energy when improving the image quality formed on the recording medium with the image quality improving treatment liquid. Is.

[Configuration of image forming apparatus]
First, an example of an image forming apparatus including a liquid applying apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a perspective view of the image forming apparatus as viewed from the front side.
This image forming apparatus includes an apparatus main body 1, a paper feed tray 2 for loading paper (recording medium) mounted on the apparatus main body 1, and a paper mounted on the apparatus main body 1 on which an image is recorded (formed). And a discharge tray 3 for stocking, and further, on one end portion side of the front surface 4 of the apparatus main body 1, a cartridge loading portion 6 that protrudes forward from the front surface 4 and is lower than the upper surface 5. An operation unit 7 such as operation keys and a display is arranged on the upper surface of the cartridge loading unit 6.
A main tank (hereinafter referred to as “ink cartridge”) 10 that is a liquid storage tank as a liquid replenishing unit is replaceably mounted on the cartridge loading unit 6, and has a front cover 8 that can be opened and closed. Yes.

Next, the mechanism of this image forming apparatus will be described with reference to FIGS. FIG. 2 is a schematic configuration diagram of the mechanism section viewed from above the apparatus main body, and FIG. 3 is a schematic configuration diagram of the mechanism section viewed from the side of the apparatus main body.
In FIG. 2, a carriage 33 is slidably held in the main scanning direction by a guide rod 31 and a stay 32, which are guide members horizontally mounted on the left and right side plates 21A and 21B constituting the frame 21, and a main scanning motor (not shown). 2 to move and scan in the direction indicated by the arrow in FIG. 2 (carriage scanning direction: main scanning direction).
The carriage 33 is provided with a plurality of recording heads 35 including ink jet heads that are droplet discharge heads for discharging recording liquid droplets (ink droplets) in a direction in which the plurality of nozzles intersect the main scanning direction. They are arranged and mounted with the ink droplet discharge direction facing downward.

Here, the recording head 35 includes, for example, a recording head 35y that discharges yellow (Y) droplets, a recording head 35m that discharges magenta (M) droplets, and a recording head 35c that discharges cyan (C) droplets. And a recording head 35k for discharging black (Bk) droplets. Of course, color inks other than the four colors exemplified here may be used.
The “recording head 35” does not distinguish between colors. Further, the head configuration is not limited to these examples, and it may be configured by using one or a plurality of recording heads having one or a plurality of nozzle rows that eject droplets of one or a plurality of colors.
The droplet discharge head constituting the recording head 35 includes a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a metal phase caused by a temperature change. A shape memory alloy actuator using a change or an electrostatic actuator using an electrostatic force can be used as an energy generating means for discharging a droplet.

Also, the carriage 33 is equipped with sub tanks 34y, 34m, 34c, and 34k for each color for supplying each color recording liquid to each recording head 35 (referred to as "sub tank 34" if the colors are not distinguished). Yes. The sub-tank 34 is supplied with the recording liquid from the ink cartridges 10 of the respective colors (referred to as “ink cartridges 10y, 10m, 10c, and 10k” when different colors are distinguished) through the recording liquid supply tubes 37 of the respective colors. It is supposed to be.
As shown in FIG. 2, the ink cartridge 10 is stored in the cartridge loading unit 6, and the cartridge loading unit 6 is provided with a supply pump unit 23 for feeding the recording liquid in the ink cartridge 10. Yes. Further, the recording liquid supply tube 37 from the ink cartridge loading unit 6 to the sub tank 34 is fixedly held by the main body side holder 25 on the rear plate 21C constituting the frame 21 in the middle of scooping. Further, it is fixed on the carriage 33 by the fixing rib 26. Reference numeral 22 denotes a signal cable for driving the recording head.

On the other hand, as shown in FIG. 3, a sheet (recording medium) 42 from the sheet stacking unit 41 serves as a sheet feeding unit for feeding sheets 42 stacked on the sheet stacking unit (bottom plate) 41 of the sheet feeding tray 2. A sheet feeding roller (half-moon roller) 43 that separates and feeds the sheets one by one and a separation pad 44 made of a material having a large friction coefficient facing the sheet feeding roller 43 are provided. Is biased to the side.
A first processing unit 70 that performs processing for promoting water absorption of the paper fed from the paper feeding unit, and a processing liquid that improves image quality by preventing ink bleeding. The processed paper 42 is conveyed to the recording head section through the second processing section 80 for applying the above. As a transport unit for transporting the paper 42 below the recording head 35, a transport belt 51 for transporting the paper 42 by electrostatic adsorption is provided. Further, a charging roller 56 which is a charging unit for charging the surface of the transport belt 51 is provided.

The transport belt 51 is an endless belt, and is configured to be looped around the transport roller 57 and the tension roller 58 in the belt transport direction of FIG. The charging roller 56 is arranged so as to contact the surface layer of the conveyor belt 51 and rotate following the rotation of the conveyor belt 51, and 2.5N is applied to both ends of the shaft as a pressing force.
In addition, a guide member 61 is disposed on the back side of the conveyance belt 51 so as to correspond to a printing area by the recording head 35. The upper surface of the guide member 61 protrudes closer to the recording head 35 than the tangent line of the two rollers (the conveyance roller 57 and the tension roller 58) that support the conveyance belt 51. Thereby, since the conveyance belt 51 is pushed up and guided by the upper surface of the guide member 61 in the printing region, it is possible to maintain high-precision flatness.

Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 35, a separation claw 63 for separating the paper 42 from the transport belt 51, a paper discharge roller 64, and a paper discharge roller 65 are provided. The paper discharge tray 3 is provided below the paper discharge roller 64. Here, the height from the space between the paper discharge roller 64 and the paper discharge roller 65 to the paper discharge tray 3 is increased to some extent in order to increase the amount that can be stored in the paper discharge tray 3.
3 is a signal cable, 54 is a conveyance guide, and 55 is a pressure roller.

In addition, as shown in FIG. 2, in a non-printing region on one side (right side in FIG. 2) of the carriage 33 in the scanning direction, a liquid ejection device that is a device for maintaining and recovering the nozzle state of the recording head 35 Maintenance / recovery device (hereinafter also referred to as “sub-system”) 91 is arranged.
The subsystem 91 includes cap members 92a to 92d for capping each nozzle surface of the recording head 35 (referred to as “cap member 92” when not distinguished), and a blade member for wiping the nozzle surface. When performing an idle discharge for discharging a certain wiper blade 93 and a droplet that does not contribute to recording in order to discharge the thickened recording liquid, an empty discharge receiver 94 for receiving the droplet, and the empty discharge receiver 94 are integrally formed. The wiper cleaner 95, which is a cleaning member for removing the recording liquid adhering to the wiper blade 93, and the cleaner roller 96 constituting the cleaner means for pressing the wiper blade 93 against the wiper cleaner 95 side when the wiper blade 93 is cleaned. It has.
In addition, as shown in FIG. 2, in the non-printing area on the other side (left side in FIG. 2) of the carriage 33 in the scanning direction, liquid droplets that do not contribute to recording because the recording liquid thickened during recording or the like is discharged. When performing the idle ejection for ejecting droplets, an idle ejection receiver 98 for receiving droplets is disposed, and the idle ejection receiver 98 is provided with an opening 99 along the nozzle row direction of the recording head 35 and the like.

[Operation of image forming apparatus]
In the ink jet recording apparatus configured as described above, as shown in FIGS. 2 and 3, the sheets (recording medium) 42 are separated and fed one by one from the sheet feeding tray 2, and the first processing unit 70 and the first processing unit 70. Guided to the conveyor belt 51 through the liquid applicator of the second processing unit 80.
At this time, an alternating voltage in which a positive output and a negative output are alternately repeated is applied from the high voltage power source to the charging roller 56 by a control circuit (not shown), whereby the conveying belt 51 has an alternating charging voltage pattern, that is, a rotating direction. In the sub-scanning direction, plus and minus are alternately charged in a band shape with a predetermined width. When the paper 42 is fed onto the conveyance belt 51 charged with the plus and minus alternately, the paper 42 is electrostatically attracted to the conveyance belt 51 and conveyed in the sub-scanning direction by the circumferential movement of the conveyance belt 51. Is done.

Therefore, by driving the recording head 35 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to perform recording for one line, and then the paper 42 is loaded. After carrying a predetermined amount, the next line is recorded. When a recording end signal or a signal that the trailing edge of the paper 42 reaches the recording area is received, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.
During printing (recording) standby, the carriage 33 is moved to the subsystem 91 side, the recording head 35 is capped by the cap member 92, and the nozzles are kept in a wet state, thereby preventing ejection failure due to ink drying. To do. Further, a recovery operation is performed in which the recording liquid is sucked (referred to as “nozzle suction” or “head suction”) from the nozzle while the recording head 35 is capped by the cap member 92 and the thickened recording liquid or bubbles are discharged. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 35 can be maintained.

[Recording head unit and recording head]
The recording head unit will be described with reference to FIGS. 4 and 5 are a plan view and a front view of the recording head unit.
As shown in FIG. 4, the recording head unit is fixed to the carriage 33. The recording head 35y ejects yellow (Y) droplets, the recording head 35m ejects magenta (M) droplets, The recording head unit is configured by the recording head 35c that discharges cyan (C) droplets and the recording head 35k that discharges black (Bk) droplets. Also, sub-tanks 34y, 34m, 34c, and 34k for each color for supplying the recording liquids of the respective colors to the respective recording heads 35 (referred to as “sub-tanks 34” when colors are not distinguished) are mounted.
As shown in FIG. 5, electric wiring (FPC: flexible printed wiring) 103 is mounted on both sides of the sub tank 34, and an image signal for operating the recording head 35 is transmitted through the wiring. An ink supply port 102 is mounted on the sub tank 34, and the ink passes through the recording liquid supply tube 37 and is replenished into the sub tank 34 from the ink supply port 102.

Next, components constituting the recording head will be described with reference to FIG.
As shown in FIG. 6, a nozzle plate 104 is affixed on the base member 105 to the front end surface of the recording head 35, and the nozzle plate 104 has many fine ink discharge ports (nozzles). Is formed. The recording head 35 mainly includes a nozzle plate 104, a base member 105, and a frame 106, and a sub tank 34 is attached to a surface opposite to the nozzle plate 104 of the recording head. In addition, an electrical wiring 103 for transmitting an electrical signal is attached to the recording head 35.

[Explanation about ink]
In the recording liquid (ink) used in the image forming apparatus of the present invention, either a pigment or a dye can be used as the color material, or a mixture of these can be used.
<Face>
Although there is no limitation in particular as a pigment used for the said recording liquid, For example, the pigments listed below are used suitably. Moreover, you may use these pigments in mixture of multiple types.
Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. It is done.
Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

  These pigments preferably have a particle size of 0.01 to 0.30 μm. If the particle size is 0.01 μm or less, the particle size approaches that of the dye, and light resistance and feathering deteriorate. On the other hand, if it is 0.30 μm or more, clogging of the discharge port or clogging with a filter in the printer occurs, and it is not possible to obtain discharge stability.

The carbon black used in the black pigment ink is carbon black produced by the furnace method or channel method, the primary particle size is 15 to 40 millimicrons, the specific surface area by the BET method is 50 to 300 square meters / g, DBP oil absorption Those having an amount of 40 to 150 ml / 100 g, a volatile content of 0.5 to 10% and a pH value of 2 to 9 are preferred.
For example, No. 2300, No. 900, MCF-88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No. 2200B (Mitsubishi, Chemical), Raven700, 5750, 5250, 5000, 3500, 1255 (above Colombia), Regal400R, 330R, 660R, MululL, Monarch700, 800, 880, 900, 1000 1100, 1300, Monarch 1400 (above, manufactured by Cabot), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4 A, 4 (made by Degussa) or the like can be used, but is not limited thereto.

Specific examples of color pigments are listed below.
Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. It is done. Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

Specific examples according to color are as follows.
Examples of pigments that can be used in yellow ink include, for example, C.I. Pigment Yellow 1, 2, 2, 3, 12, 14, 16, 17, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 129, 151, 154, etc., but are not limited thereto.
Examples of pigments that can be used in magenta ink include, for example, C.I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 123, 168, 184, 202, etc. However, it is not limited to these.
Examples of pigments that can be used for cyan ink include, for example, C.I. Pigment Blue 1, 2, 3, 15, 15: 3, 15:34, 16, 22, 22, 60, C.I. Examples thereof include, but are not limited to, Bat Blue 4 and 60.

Further, the pigment contained in each ink used in the image forming apparatus of the present invention may be newly produced for the present invention.
The pigments listed above can be made into an ink jet recording liquid by dispersing them in an aqueous medium using a polymer dispersant or a surfactant. As a dispersant for dispersing such organic pigment powder, a normal water-soluble resin or a water-soluble surfactant can be used.

  Specific examples of water-soluble resins include styrene, styrene derivatives, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itacon. Examples thereof include block copolymers consisting of at least two monomers selected from acids, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, etc., random copolymers, or salts thereof. These water-soluble resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved. Among them, a resin having a weight average molecular weight of 3000 to 20000 is used as a dispersion when used in an inkjet recording liquid. It is particularly preferred because of the advantages that it can be reduced in viscosity and can be easily dispersed.

The simultaneous use of the polymer dispersant and the self-dispersing pigment is a preferable combination because an appropriate dot diameter can be obtained. The reason is not clear, but it is thought as follows.
By containing the polymer dispersant, the penetration into the recording paper (recording medium) is suppressed. On the other hand, since the aggregation of the self-dispersing pigment is suppressed by containing the polymer dispersant, the self-dispersing pigment can smoothly spread in the lateral direction. Therefore, it is considered that the dots spread widely and thinly and ideal dots can be formed.

  Moreover, the following are mentioned as a specific example of the water-soluble surfactant which can be used as a dispersing agent. For example, anionic surfactants include higher fatty acid salts, alkyl sulfates, alkyl ether sulfates, alkyl ester sulfates, alkyl aryl ether sulfates, alkyl sulfonates, sulfosuccinates, alkyl allyls and alkyl naphthalene sulfonic acids. Examples thereof include salts, alkyl phosphates, polyoxyethylene alkyl ether phosphate esters, and alkyl allyl ether phosphates. Examples of the cationic surfactant include alkylamine salts, dialkylamine salts, tetraalkylammonium salts, benzalkonium salts, alkylpyridinium salts, imidazolinium salts, and the like. Furthermore, examples of the amphoteric surfactant include dimethylalkyl lauryl betaine, alkyl glycine, alkyl di (aminoethyl) glycine, imidazolinium betaine and the like. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, sucrose ester, glycerin ester polyoxyethylene ether, sorbitan Examples thereof include polyoxyethylene ethers of esters, polyoxyethylene ethers of sorbitol esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, amine oxides, and polyoxyethylene alkylamines.

Further, the pigment can be provided with dispersibility by coating with a resin having a hydrophilic group and encapsulating the pigment.
As a method for coating a water-insoluble pigment with an organic polymer and microencapsulating, all conventionally known methods can be used. Conventionally known methods include chemical production methods, physical production methods, physicochemical methods, mechanical production methods, and the like. In particular,
(1) Interfacial polymerization method (a method in which two kinds of monomers or two kinds of reactants are dissolved separately in a dispersed phase and a continuous phase, and both substances are reacted at the interface between them to form a wall film)
(2) In-situ polymerization method (a method in which a liquid or gaseous monomer and catalyst, or two reactive substances are supplied from either one of the continuous phase core particles to cause a reaction to form a wall film)
(3) Liquid-cured coating method (method of forming a wall film by insolubilizing droplets of a polymer solution containing core material particles in a liquid with a curing agent)
(4) Coacervation (phase separation) method (a method in which a polymer dispersion in which core material particles are dispersed is separated into a coacervate (concentrated phase) having a high polymer concentration and a dilute phase to form a wall membrane)
(5) In-liquid drying method (preparing a liquid in which a core substance is dispersed in a solution of a wall membrane material, placing the dispersion in a liquid in which the continuous phase of this dispersion is not miscible to form a composite emulsion, Method of forming a wall film by gradually removing the dissolved medium)
(6) Melt-dispersed cooling method (using a wall film material that melts into a liquid state and solidifies at room temperature when heated, this material is heated and liquefied, core material particles are dispersed therein, and it is cooled into fine particles. A method of forming a wall film)
(7) Air suspension coating method (powder core material particles are suspended in the air by a fluidized bed, and the wall membrane material coating solution is sprayed and mixed while suspended in the air stream to form a wall membrane. Method)
(8) Spray drying method (method of spraying the encapsulated stock solution and bringing it into contact with hot air to evaporate and dry the volatile matter to form a wall film)
(9) Acid precipitation method (by neutralizing at least a part of the anionic group of the organic polymer compound containing an anionic group with a basic compound, thereby providing water solubility and an aqueous medium together with the colorant. After kneading with, neutralize or acidify with an acidic compound, deposit organic compounds and fix them on the colorant, then neutralize and disperse)
(10) Phase inversion emulsification method (a mixture containing an anionic organic polymer having dispersibility in water and a colorant is used as an organic solvent phase, and water is added to the organic solvent phase or water And the like).

  Examples of organic polymers (resins) used as the material constituting the microcapsule wall membrane material include polyamide, polyurethane, polyester, polyurea, epoxy resin, polycarbonate, urea resin, melamine resin, phenol resin, and polysaccharide. , Gelatin, gum arabic, dextran, casein, protein, natural rubber, carboxypolymethylene, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, cellulose, ethyl cellulose, methyl cellulose, nitrocellulose, hydroxyethyl cellulose, acetic acid Cellulose, polyethylene, polystyrene, (meth) acrylic acid polymer or copolymer, (meth) acrylic acid ester polymer or copolymer, (meth) acrylic acid- (me ) Acrylic acid ester copolymer, styrene - (meth) acrylic acid copolymer, styrene - maleic acid copolymer, sodium alginate, fatty acids, paraffin, beeswax, water wax, hardened beef tallow, carnauba wax, and albumin.

  Among these, organic polymers having an anionic group such as a carboxylic acid group or a sulfonic acid group can be used. Examples of the nonionic organic polymer include polyvinyl alcohol, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate, or a (co) polymer thereof, and a cationic ring-opening polymer of 2-oxazoline. Is mentioned. In particular, a completely quark of polyvinyl alcohol is particularly preferred because it has low water solubility and is easy to dissolve in hot water but difficult to dissolve in cold water.

  The amount of the organic polymer constituting the wall film material of the microcapsule is 1% by weight or more and 20% by weight or less with respect to a water-insoluble colorant such as an organic pigment or carbon black. By setting the amount of the organic polymer within the above range, the content of the organic polymer in the capsule is relatively low, so that the color development property of the pigment caused by the organic polymer covering the pigment surface is reduced. It is possible to suppress the decrease. If the amount of the organic polymer is less than 1% by weight, it is difficult to exert the effect of encapsulation. Conversely, if the amount exceeds 20% by weight, the color developability of the pigment is significantly reduced. In consideration of other characteristics, the amount of the organic polymer is preferably in the range of 5 to 10% by weight based on the water-insoluble colorant.

  That is, since a part of the color material is exposed without being substantially covered, it is possible to suppress a decrease in color developability, and conversely, a part of the color material is not exposed and is substantially not exposed. Therefore, the effect of the pigment coating can be exhibited at the same time. The number average molecular weight of the organic polymers used in the present invention is preferably 2000 or more from the viewpoint of capsule production. Here, “substantially exposed” means not the partial exposure associated with defects such as pinholes and cracks, but a state where it is intentionally exposed.

Furthermore, if an organic pigment or a self-dispersing carbon black, which is a self-dispersing pigment, is used as a colorant, the dispersibility of the pigment is improved even when the content of the organic polymer in the capsule is relatively low. In addition, since sufficient storage stability of the ink can be secured, it is more preferable for the present invention.
It is preferable to select an organic polymer suitable for the microencapsulation method. For example, in the case of interfacial polymerization, polyester, polyamide, polyurethane, polyvinyl pyrrolidone, epoxy resin and the like are suitable. In the case of using the in-situ polymerization method, a polymer or copolymer of (meth) acrylic acid ester, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, Polyvinyl chloride, polyvinylidene chloride, polyamide and the like are suitable. In the case of the liquid curing method, sodium alginate, polyvinyl alcohol, gelatin, albumin, epoxy resin and the like are suitable. In the case of the coacervation method, gelatin, celluloses, casein and the like are suitable. In addition, in order to obtain a fine and uniform microencapsulated pigment, it is of course possible to use all conventionally known encapsulation methods other than those described above.

  When the phase inversion method or the acid precipitation method is selected as the microencapsulation method, anionic organic polymers are used as the organic polymers constituting the wall membrane material of the microcapsules. The phase inversion method is a composite or composite of an anionic organic polymer having self-dispersibility or solubility in water and a colorant such as a self-dispersion organic pigment or self-dispersion carbon black, or a self-dispersion method. A mixture of a colorant such as a dispersible organic pigment or self-dispersing carbon black, a curing agent, and an anionic organic polymer is used as an organic solvent phase, and water is added to the organic solvent phase or the organic solvent is submerged in water. In this method, a solvent phase is introduced and microencapsulated while self-dispersing (phase inversion emulsification). In the above phase inversion method, there is no problem even if the organic solvent phase is mixed with a recording liquid vehicle or additives. In particular, it is more preferable to mix a liquid medium of a recording liquid because a dispersion liquid for recording liquid can be directly produced.

  On the other hand, in the acid precipitation method, a part or all of the anionic group of the anionic group-containing organic polymer is neutralized with a basic compound, a colorant such as a self-dispersing organic pigment or self-dispersing carbon black, A water-containing cake obtained by a production method comprising a step of kneading in an aqueous medium and a step of neutralizing and acidifying an acidic compound to precipitate an anionic group-containing organic polymer and fixing the pigment to a pigment, This is a method of microencapsulation by neutralizing part or all of an anionic group using a compound. By doing in this way, the aqueous dispersion containing the anionic microencapsulated pigment which is fine and contains many pigments can be manufactured.

Examples of the solvent used for microencapsulation as described above include alkyl alcohols such as methanol, ethanol, propanol and butanol; aromatic hydrocarbons such as benzol, toluol and xylol; methyl acetate Esters such as ethyl acetate and butyl acetate; Chlorinated hydrocarbons such as chloroform and ethylene dichloride; Ketones such as acetone and methyl isobutyl ketone; Ethers such as tetrahydrofuran and dioxane; Cellosolves such as methyl cellosolve and butyl cellosolve Etc. The microcapsules prepared by the above method are once separated from these solvents by centrifugation or filtration, and then stirred and redispersed with water and the necessary solvent, and used for the intended present invention. A recording liquid that can be used is obtained. The average particle diameter of the encapsulated pigment obtained by the above method is preferably 50 nm to 180 nm.
By coating the resin in this way, the pigment adheres firmly to the printed material, whereby the scratching property of the printed material can be improved.

<Dye>
The dye used in the recording liquid of the image forming apparatus of the present invention is a dye classified into an acid dye, a direct dye, a basic dye, a reactive dye, and a food dye in the color index, and has excellent water resistance and light resistance. Is used. These dyes may be used as a mixture of a plurality of types, or may be used as a mixture with other color materials such as pigments as necessary. These colorants are added as long as the effects of the present invention are not inhibited.

(A) Acid dyes and food dyes CI Acid Yellow 17, 23, 42, 44, 79, 142
C.I. Acid Red 1,8,13,14,18,26,27,35,37,42,52,82,87,89,92,97,106,111,114,115,134,186,249,254 289
C.I. Acid Blue 9, 29, 45, 92, 249
C.I. Acid Black 1, 2, 7, 24, 26, 94
C.I. Food Yellow 3, 4
C.I. Food Red 7, 9, 14
C.I. Food Black 1, 2

(B) As a direct dye C.I. Direct yellow 1,12,24,26,33,44,50,86,120,132,142,144
C.I. Direct Red 1,4,9,13,17,20,28,31,39,80,81,83,89,225,227
C.I. Direct orange 26, 29, 62, 102
C.I. Direct blue 1,2,6,15,22,25,71,76,79,86,87,90,98,163,165,199,202
C.I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171

(C) As a basic dye C.I. Basic yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 64, 65 67, 70, 73, 77, 87, 91
C.I. Basic Red 2,12,13,14,15,18,22,23,24,27,29,35,36,38,39,46,49,51,52,54,59,68,69,70 73, 78, 82, 102, 104, 109, 112
C.I. Basic blue 1,3,5,7,9,21,22,26,35,41,45,47,54,62,65,66,67,69,75,77,78,89,92,93 , 105, 117, 120, 122, 124, 129, 137, 141, 147, 155
C.I. Basic Black 2,8

(D) As a reactive dye, C.I. Reactive Black 3, 4, 7, 11, 12, 17
C.I. Reactive Yellow 1,5,11,13,14,20,21,22,25,40,47,51,55,65,67
C.I. Reactive Red 1,14,17,25,26,32,37,44,46,55,60,66,74,79,96,97
C.I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95, etc. can be used.

<Additives and physical properties common to dyes and pigments>
In order to make the recording liquid used in the image forming apparatus of the present invention have desired physical properties or to prevent clogging of the nozzles of the recording head due to drying, a water-soluble organic solvent is used in addition to the coloring material. Is preferred. This water-soluble organic solvent includes a wetting agent and a penetrating agent.
The wetting agent is added for the purpose of preventing clogging of the nozzles of the recording head due to drying. Specific examples of this wetting agent include the following.
Ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 1,2,4-butanetriol, 1, Polyhydric alcohols such as 2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene Polyhydric alcohol alkyl ethers such as ethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; N-methyl-2 Nitrogen-containing heterocyclic compounds such as pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; formamide, N-methylformamide, formamide, N, N-dimethyl Amides such as formamide; amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine, dimethyl sulfoxide, And sulfur-containing compounds such as sulfolane and thiodiethanol, propylene carbonate, ethylene carbonate, and γ-butyrolactone. These solvents are used alone or in combination with water.

  Further, the penetrant is added for the purpose of improving the wettability between the recording liquid and the recording medium (recording material) and adjusting the penetration speed. As the penetrant, those represented by the following formulas (I) to (IV) are preferable. Namely, a polyoxyethylene alkylphenyl ether surfactant of formula (I), an acetylene glycol surfactant of formula (II), a polyoxyethylene alkyl ether surfactant of formula (III), and a formula (IV) Since the polyoxyethylene polyoxypropylene alkyl ether type surfactant can reduce the surface tension of the recording liquid, it can improve wettability and increase the penetration rate.

(R is an optionally branched hydrocarbon chain having 6 to 14 carbon atoms, k is 5 to 20)

(M and n are 0 to 40)

(R is a C6-C14 hydrocarbon chain which may be branched, n is 5-20)

(R is a hydrocarbon chain having 6 to 14 carbon atoms, m and n are numbers of 20 or less)

  Other than the compounds of the above formulas (I) to (IV), for example, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene Alkyl and aryl ethers of polyhydric alcohols such as glycol chlorophenyl ether, nonionic surfactants such as polyoxyethylene polyoxypropylene block copolymers, fluorosurfactants, lower alcohols such as ethanol and 2-propanol Although it can be used, diethylene glycol monobutyl ether is particularly preferable.

The surface tension of the recording liquid used in the image forming apparatus of the present invention is preferably 20 to 60 dyne / cm. From the viewpoint of achieving both wettability with the recording medium and droplet formation, 30 to 50 dyne / cm. More preferably.
The viscosity of the recording liquid used in the image forming apparatus of the present invention is preferably 1.0 to 20.0 cP, and more preferably 3.0 to 10.0 cP from the viewpoint of ejection stability.
Further, the pH of the recording liquid used in the image forming apparatus of the present invention is preferably 3 to 11, and more preferably 6 to 10 from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

The recording liquid used in the image forming apparatus of the present invention can contain an antiseptic / antifungal agent. By containing the antiseptic / antifungal agent, the growth of bacteria can be suppressed, and the storage stability and the image quality stability can be improved. Examples of antiseptic / antifungal agents include benzotriazole, sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, isothiazoline-based compounds, sodium benzoate, and sodium pentachlorophenol.
The recording liquid used in the image forming apparatus of the present invention can contain a rust inhibitor. By containing a rust preventive agent, it is possible to form a film on the metal surface in contact with the recording head or the like and prevent corrosion. As the rust inhibitor, for example, acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like can be used.

  The recording liquid used in the image forming apparatus of the present invention can contain an antioxidant. By containing an antioxidant, even when a radical species causing corrosion is generated, the antioxidant can be prevented by eliminating the radical species. Representative examples of the antioxidant include phenolic compounds and amine compounds.

  Examples of phenolic compounds include compounds such as hydroquinone and gallate, 2,6-di-tert-butyl-p-cresol, stearyl-β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert) -Butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-) -Tert-4-hydroxybenzyl) benzene, tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, tetrakis [meth Down -3 (3 ', 5'-di -tert- butyl-4-hydroxyphenyl) propionate] hindered phenol compounds such as methane and the like.

  Examples of amine compounds include N, N′-diphenyl-p-phenylenediamine, phenyl-β-naphthylamine, phenyl-α-naphthylamine, N, N′-β-naphthyl-p-phenylenediamine, N, N′-. Examples include diphenylethylenediamine, phenothiazine, N, N′-di-sec-butyl-p-phenylenediamine, 4,4′-tetramethyl-diaminodiphenylmethane, and the like.

  The recording liquid used in the image forming apparatus of the present invention can contain a pH adjuster. Examples of the pH adjuster include hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, lithium carbonate, Examples include alkali metal carbonates such as sodium carbonate and potassium carbonate, amines such as diethanolamine and triethanolamine, boric acid, hydrochloric acid, nitric acid, sulfuric acid, and acetic acid.

[First processing unit and second processing unit]
Next, the image quality is improved by aggregating a first processing unit 70 for applying a processing liquid for promoting water absorption of a recording medium such as transfer paper that is not non-absorbing, and an ink composition containing at least a coloring material. The 2nd process part 80 which provides the process liquid for improvement is demonstrated referring FIG. FIG. 7 is a schematic diagram illustrating the configuration of the first processing unit and the second processing unit.
The first processing unit 70 is a liquid application device (liquid coating device) for applying a treatment liquid for hydrophilizing the surface of the recording medium to promote water absorption, and includes a surfactant. A tank 71 for storing the liquid, a supply roller 72 installed so that at least a part of the water absorption promoting treatment liquid in the tank 71 is in contact with the liquid, and the cylindrical surface of the supply roller 72 is parallel to the rotation axis. The coating roller 73 provided in this manner and the opposing roller 74 provided so that the rotation axis is parallel to the coating roller 73 and the cylindrical surface is in contact with the coating roller 73. The supply roller 72 pumps up the processing liquid in the tank 71 and supplies it to the application roller 73. The water absorption promoting treatment liquid may be separately provided with a storage tank and replenished from the storage tank to the tank 71 as necessary.

  The supply roller 72 and the application roller 73 are in contact with each other so as to have a substantially uniform pressure in the axial direction, and a certain amount of the processing liquid pumped up by the supply roller 72 passes through the nip between both rollers, and the application roller 73. A liquid film of the processing liquid is formed on the cylindrical surface. If necessary, a plurality of supply rollers may be provided, or an intermediate roller may be further provided between the application roller 73. The rotation of the supply roller 72 and the application roller 73 may be constant or may have a linear velocity difference. If the configuration can form an average uniform amount of liquid film on the application roller 73, It is not limited to this. In the example shown in FIG. 7, the supply roller 72 and the counter roller 74 are arranged at positions facing each other with the application roller 73 interposed therebetween, but this positional relationship is not limited to this. The processing liquid on the surface of the application roller 73 is configured to be applied to the surface of the recording medium when the recording medium passes between the opposing roller 74.

The second processing unit 80 is a liquid application device that applies a processing liquid for preventing ink bleeding and improving the image quality. Like the first processing unit 70, the tank 81 that stores the processing liquid is used. , A supply roller 82, an application roller 83, and a counter roller 84, and the processing liquid in the tank 81 becomes an image quality improvement processing liquid containing an aggregating agent that aggregates the ink composition containing the color material. This treatment liquid can be applied to the surface of the recording medium.
Although the example of the roll coater with which thin layer application | coating is easy was shown as a liquid provision apparatus in said 1st process part and 2nd process part, it is not restricted to this, Even if it is a spray coater, a slit coater, etc. I do not care. Moreover, the structure which provides a process liquid to the recording-medium surface by an inkjet system may be sufficient.

In the first processing unit 70, the water absorption of the recording medium is improved by applying a processing liquid containing a surfactant to the surface of the recording medium and making the surface hydrophilic.
In general, a sizing agent is applied to a recording medium (transfer paper) used in an image forming apparatus for the purpose of improving resistance to water. In addition to starch, there are many sizing agents such as carboxymethyl cellulose, polyvinyl alcohol, alginic acid, polyacrylamide (PAM), and ketene dimer. A starch-containing surface sizing agent in which starch is polymerized with styrene and an acrylic polymer (which is considered to have some chemical bond) has also been developed. This sizing agent has both resistance and receptivity to inkjet water-based ink, has good dispersion of the sizing agent, and improves printing quality. Due to the effect of the sizing agent, the inherently hydrophilic pulp fiber becomes water repellent, and the water absorption of the recording medium is lowered.
Therefore, the water absorption of the recording medium can be improved by applying a surfactant to the surface to make it hydrophilic.

  Examples of such surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl sorbitan esters, polyoxyethylene alkyl amines, glycerin fatty acids. Nonionic surfactants such as esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, polyoxyethylene glycol fatty acid esters; alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl ether acetic acid solutions, alkylbenzenes Anionic surfactants such as sulfonates, N-acylamino acid salts, alkylsulfosuccinates and alkylphosphates; 4 such as benzalkonium salts Cationic surfactants such as amines; perfluoroalkyl phosphoric acid esters, perfluoroalkyl carboxylic acid salts, and fluorine-based surfactants such as perfluoroalkyl betaines, and the like.

Among these, more specific and preferred penetrants are diethylene glycol monobutyl ether, diethylene glycol monophenyl ether, propylene glycol monobutyl ether, and a fluorosurfactant, which have a large effect of increasing permeability.
One or more aqueous solutions of these surfactants may be applied, and the amount of these surfactants to be added varies depending on the type, but 0.05 to 10% by mass is about 10 to 200 mg / A4. It is preferable to give. When the application amount increases, it causes the recording medium (recording paper) to be curled or wavy due to the moisture of the treatment liquid. Therefore, the application amount is preferably suppressed to about 10 to 100 mg / A4.
Furthermore, for preventing volatilization, for example, polyethylene glycol, polypropylene glycol, ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, thiodiglycol, hexylene glycol, diethylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, glycerin, etc. The water-soluble organic solvent may be added as appropriate.

  As a first processing unit 70 that promotes water absorption of a recording medium such as transfer paper that is not non-absorbable, as shown in FIGS. 8-1 to 8-3, a processing liquid application apparatus (processing liquid coating apparatus) is used. Instead, there is a method of irradiating energy by plasma discharge, corona discharge, or charging by providing the plasma irradiation device 111, the corona discharge device 112, or the charging roller device 113. As the plasma irradiation apparatus 111, if an atmospheric pressure plasma discharge apparatus that performs processing under atmospheric pressure without reducing pressure is used, an apparatus for reducing pressure is unnecessary, and the apparatus can be incorporated in an image forming apparatus. The corona discharge device 112 and the charging roller device 113 are used for charging a photosensitive member of an electrophotographic image forming apparatus, and are small in size and can be easily incorporated into an image forming apparatus as in the present invention. .

  In the second processing unit 80, an image quality improvement processing liquid containing an aggregating agent that aggregates a coloring material such as a pigment contained in the ink is applied. When an image is formed on the ink jet system, the pigment in the ink aggregates due to the action of the treatment liquid, and an image without bleeding can be obtained. During this aggregation, the vehicle component of the ink is separated, and the pigment aggregated and formed into a film on the surface of the recording medium (transfer paper), which causes problems such as setback due to delayed penetration into the recording medium. However, since the surface of the recording medium is made hydrophilic in advance in the first processing unit 70, the penetration of the vehicle component separated from the pigment into the recording medium is promoted, thereby causing problems such as set-off. Only the image quality can be improved.

  As such an aggregating agent, a compound for aggregating or precipitating the coloring material contained in the ink is contained. It is not particularly limited as long as it has this function, but it is one or more compounds selected from organic acids, polyvalent metal salts, and polyamines from the viewpoints of solubility and ink storage stability. Is preferred.

-Organic acid-
Specific examples of the organic acid include 2-pyrrolidone-5-carboxylic acid, 4-methyl-4-pentanolide-3-carboxylic acid, furan carboxylic acid, 2-benzofuran carboxylic acid, 5-methyl-2-furan carboxylic acid, 2,5-dimethyl-3-furancarboxylic acid, 2,5-furandicarboxylic acid, 4-butanolide-3-carboxylic acid, 3-hydroxy-4-pyrone-2,6-dicarboxylic acid, 2-pyrone-6 Carboxylic acid, 4-pyrone-2-carboxylic acid, 5-hydroxy-4-pyrone-5-carboxylic acid, 4-pyrone-2,6-dicarboxylic acid, 3-hydroxy-4-pyrone-2,6-dicarboxylic acid Thiophenecarboxylic acid, 2-pyrrolecarboxylic acid, 2,3-dimethylpyrrole-4-carboxylic acid, 2,4,5-trimethylpyrrole-3-propionic acid, 3-hydroxy-2-y Dolecarboxylic acid, 2,5-dioxo-4-methyl-3-pyrroline-3-propionic acid, 2-pyrrolidinecarboxylic acid, 4-hydroxyproline, 1-methylpyrrolidine-2-carboxylic acid, 5-carboxy-1- Methylpyrrolidine-2-acetic acid, 2-pyridinecarboxylic acid, 3-pyridinecarboxylic acid, 4-pyridinecarboxylic acid, pyridinedicarboxylic acid, pyridinetricarboxylic acid, pyridinepentacarboxylic acid, 1,2,5,6-tetrahydro-1- Methylnicotinic acid, 2-quinolinecarboxylic acid, 4-quinolinecarboxylic acid, 2-phenyl-4-quinolinecarboxylic acid, 4-hydroxy-2-quinolinecarboxylic acid, 6-methoxy-4-quinolinecarboxylic acid, phthalic acid, citric acid And compounds such as acid, tartaric acid, lactic acid, derivatives of these compounds, or salts thereof These also have functions such as pH adjustment.
Among the above organic acids, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, citric acid, succinic acid, tartaric acid, lactic acid, phthalate An acid, a derivative of these compounds, or a salt thereof.

-Multivalent metal salt-
Polyvalent metal salts include aluminum ions, barium ions, calcium ions, copper ions, iron ions, magnesium ions, manganese ions, nickel ions, tin ions, titanium ions, zinc ions, and other polyvalent metal ions, hydrochloric acid, and odorous acid. , Hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, boric acid, thiocyanic acid, and organic carboxylic acids such as acetic acid, succinic acid, lactic acid, fumaric acid, fumaric acid, citric acid, salicylic acid, phthalic acid, benzoic acid, and organic Examples include sulfonic acid salts.
Specific examples include aluminum chloride, aluminum bromide, aluminum sulfate, aluminum nitrate, sodium aluminum sulfate, potassium aluminum sulfate, aluminum acetate, barium chloride, barium bromide, barium iodide, barium oxide, barium nitrate, barium thiocyanate, Calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, calcium salicylate, calcium tartrate, calcium lactate, calcium fumarate, citric acid Calcium, copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetate, iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, iron oxalate, iron lactate, iron fumarate, iron citrate, chloride Magnesium, Magnesium bromide Cium, magnesium iodide, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium lactate, manganese chloride, manganese sulfate, manganese nitrate, manganese dihydrogen phosphate, manganese acetate, manganese salicylate, manganese benzoate, manganese lactate, nickel chloride, odor And salts of polyvalent metals such as nickel fluoride, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate, titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, zinc thiocyanate, and zinc acetate.

-Polyamines-
Examples thereof include diallyldimethylammonium chloride polymers, diallylamine polymers, monoallylamine polymers, onium salts such as sulfonium salts and phosphonium salts of these compounds, and phosphate esters.

In the present invention, the flocculant may be used alone or in combination of two or more. Further, the addition amount of the flocculant in the treatment liquid composition is preferably 5% by mass or more and 30% by mass or less from the viewpoint of solubility. The amount of the treatment liquid applied to the recording medium is 10 to 10%. About 200 mg / A4 is preferable. More preferably, it is preferable to apply about 10 to 100 mg / A4 of a treatment liquid containing 10 to 20% by mass of a flocculant.
When the application amount of the treatment liquid is increased, the recording medium (transfer paper) may be curled or wavy due to the moisture of the treatment liquid, and when it is less, it is difficult to apply the treatment liquid uniformly. When the amount of the flocculant added in the processing liquid is less than 5% by mass, the aggregation of the pigment becomes insufficient when the ink and the processing liquid contact and mix on the recording medium, and the image density, bleeding, color On the other hand, there is a case where the interfacial blur is deteriorated. On the other hand, even if the addition amount exceeds 30% by mass, the improvement effect on the image quality does not change so much and is wasted.

  An invention having a configuration similar to that of the present invention is described in Japanese Patent Application Laid-Open No. 2004-90596 (“Image Forming Method and Image Forming Apparatus”). In the present invention, an intermediate transfer member made of a non-absorbing material is hydrophilized, and then a reaction solution containing a metal salt is applied as an aggregating agent. Thereafter, an image is formed by an ink jet method, and this is transferred to a transfer paper. (Recording medium). In the present invention, when an image is formed on a non-absorbing material by an ink jet method, the ink is repelled. Therefore, hydrophilic treatment is performed to prevent this, and the object of the present invention is also effective. Is also different. This invention is similar to the present invention in that the color material in the ink is aggregated by the aggregating agent to improve the image quality, but the water absorption is improved even if the non-absorbing member is hydrophilized. There is no effect, and a configuration in which the vehicle component separated by agglomeration is quickly absorbed into a recording medium having a hydrophilic surface and improved water absorption performance as in the present invention is not easily conceivable.

In the present invention, as shown in FIG. 7, after the surface of the recording medium is hydrophilized by the first processing unit 70 to improve the water absorption from the surface, the second processing unit 80 uses the ink. In this image forming apparatus, a treatment liquid containing an aggregating agent for aggregating a pigment, which is a coloring material therein, is applied, and then an ink is applied by an inkjet method to form an image.
The first processing unit 70 may be before or after the second processing unit 80, but it is preferable to perform processing by the second processing unit 80 after processing by the first processing unit 70. The reason is that the processing liquid applied by the second processing unit 80 is such that the flocculant in the processing liquid comes into contact with the ink and causes the coloring material in the ink to aggregate. Bleeding is less likely to occur in That is, it is desirable that this agglomeration reaction occurs between the time when the ink comes into contact with the surface of the recording medium and the time when the ink starts to penetrate inside. If the ink penetrates into the interior and then aggregates in contact with the processing liquid, the ink coloring material has already penetrated to some extent inside the recording medium, and bleeding has occurred in the previous penetration process. This is because it occurs.

  On the other hand, when the second processing unit 80 has applied the image quality improving treatment liquid and then the first processing unit 70 performs the process of applying a surfactant that promotes water absorption, the second processing unit 80 Since the water absorption promoting treatment liquid is applied so as to cover the applied image quality improvement treatment agent, the ink color material is recorded on the recording medium until the ink color material contacts and aggregates with the flocculant of the image quality improvement treatment liquid. Since it will begin to penetrate inside, the effect of suppressing bleeding and improving image quality will be weakened.

As described in Japanese Patent No. 2675001 (Japanese Patent Laid-Open No. 63-299970, “Inkjet Recording Method”), a surfactant may be contained in the image quality improving treatment liquid. In many cases, a surfactant is generally used to uniformly apply the image quality improving treatment liquid to the surface of the recording medium. Even if it does in this way, it will be effective in improving the permeability of the ink to a recording medium, will contribute also to penetration of the vehicle component after aggregation, and it will also have the effect of improving dryness.
However, as in the case where the image quality improvement processing liquid is applied previously, the color material of the ink is recorded on the recording medium by the surfactant in the processing liquid until the color material is aggregated by the coagulant in the image quality improvement processing liquid. The effect of the image quality improvement processing liquid is weakened. For this reason, the amount of the flocculant in the image quality improvement processing liquid is increased beyond the necessary amount, which is wasted. Further, depending on the combination with the flocculant, there is a problem that the effect of the flocculant is weakened or precipitated. For example, when a polyvalent metal salt is used as the flocculant, the ionic surfactant reacts with the metal salt and precipitates, or when an organic acid is used as the flocculant, the cationic surfactant There are restrictions such as the inability to use surfactants.

The recording medium used in the apparatus of the present invention is selected by the user according to the purpose, and there are many types. There is a large difference in water absorption performance depending on the recording medium. If the same processing is performed on all of these recording media, sufficient processing cannot be performed or the processing liquid is wasted. FIG. 9 shows the water absorption of various recording media (transfer papers) measured by the JIS P 8122 paper's Steecht sizing test method.
As described above, the process for promoting the water absorption of the recording medium is performed by reducing the hydrophobic effect of the sizing agent used for the purpose of imparting water resistance to the recording medium. If a surfactant is applied as an agent, the effect of promoting water absorption can be controlled by adjusting the applied amount.

In the roll coater type treatment liquid application apparatus shown in FIG. 7, the amount of the treatment liquid to be applied is determined by the amount of the treatment liquid passing through the nip portion between the supply roller 72 and the application roller 73, and passes through the nip portion. If the surfaces of the supply roller 72 and the application roller 73 are smooth, the amount of the processing liquid to be determined is determined by the viscosity of the processing liquid and the pressure at the nip between the rollers. Since the viscosity of the processing liquid is determined by the processing liquid, the amount of the processing liquid passing through the nip portion can be controlled by adjusting the pressure at the nip between the rollers.
FIG. 10 shows an adjustment mechanism 75 that adjusts the pressure at the nip between the rollers. The adjustment mechanism 75 can control the amount of treatment liquid applied. The supply roller 72 is pressed against the application roller 73 by a pressure spring 77 via a pressure lever 76. By adjusting the pressing force of the pressure spring 77 with the adjusting cam 78, the pressure between the rollers can be adjusted. By providing the pressure levers 76 at both ends of the supply roller 72, the pressure can be uniformly applied in the axial direction. The adjustment mechanism 75 is not limited to this, and the pressing force of the pressure spring 77 can be adjusted by rotating a screw.

Also, the application amount of the treatment liquid can be adjusted by changing the speed ratio between the supply roller 72 and the application roller 73.
According to the elastohydrodynamic lubrication theory, the amount of liquid that passes through the nip between the rollers is proportional to the average speed of the rollers of 0.6. Therefore, by changing the speed of the supply roller while keeping the speed of the application roller constant, The amount of liquid passing through the nip can be controlled. (See "Offset Printing Machine", edited by Mihara Seisakusho, Mitsubishi Heavy Industries, Ltd., written by Osamu Yorikei, published by Nihon Printing Shimbun, p. 91)
Further, the first processing unit 70 that promotes water absorption of a recording medium such as transfer paper that is not non-absorbable is a means such as plasma discharge, corona discharge, or charging roller (see FIGS. 8-1 to 8-3). In the case of the reference, the ratio of promoting water absorption can be controlled by adjusting the applied voltage or current to adjust the intensity of the irradiated energy.

Such adjustment means can be adjusted according to the input information from the operation unit of the image forming apparatus or the setting screen of a connected PC (Personal Computer), and the user can select according to the type of recording medium. It is supposed to be. Further, data that is automatically selected according to the type of recording medium selected in advance may be set. In any case, the processing state can be adjusted according to the recording medium.
As a result, it is possible to perform an appropriate process according to the water absorption of the recording medium without wastefully processing a special coated paper having a layer having good water absorption.

With coated paper that has been subjected to anti-bleeding treatment exclusively for inkjet, no image quality improving treatment liquid is required. Therefore, the second processing unit 80 may be provided with a mechanism that can switch the presence / absence of application of the image quality improvement processing liquid. In the treatment liquid applying apparatus using the roll coater shown in FIG. 7, it is preferable that the coating roller 83 is separated from the facing roller 84 to provide a gap so that the recording medium passes therethrough. The same effect can be obtained even when the supply roller 82 is stopped or separated from the application roller 83. Further, as shown in FIG. 11, by providing a path switching unit 68 in the recording medium conveyance path and switching it, the first processing unit 70 or the second processing unit 80 is not passed to the image forming unit. The recording medium may be directly conveyed.
For example, when using coated paper that has been subjected to blur prevention treatment exclusively for inkjet, the image quality improvement processing liquid is unnecessary, and therefore it can be prevented from being applied by this path switching means. Such switching may be performed from the operation unit or may be operated from the printer setting screen of the connected PC. Further, when a paper cassette is provided, a switch for designating the type of recording medium (paper type) can be provided in the paper cassette, and this can be automatically detected and switched.

  Since the dedicated paper that does not require the image quality improvement processing also has water absorption performance, if the processing in the first processing unit 70 for promoting water absorption performance is not performed in conjunction with this, There is no need to perform useless processing.

Examples of the present invention will be described below.
◇ Treatment liquid formulation to promote water absorption Diluent: 88% by weight of ion exchange water
Surfactant: Cytec Aerosol A196 2wt%
Thickener: Propylene glycol 10wt%
After all materials were mixed in water, the mixture was slowly stirred for 10 minutes to obtain a treatment solution.
◇ Image quality improvement treatment liquid formulation Diluent: Ion-exchanged water 60wt%
Flocculant: Lactic acid 20wt%
Thickener: Propylene glycol 20wt%
After all materials were mixed in water, the mixture was slowly stirred for 10 minutes to obtain an image quality improving treatment solution.

After applying the treatment liquid for promoting water absorption at 100 mg / A4 or 150 mg / A4, the image improvement treatment liquid is applied at 50 mg / A4, and further, 150 dpi at the ink discharge portion of the inkjet printer IPSIO GX5000 (manufactured by Ricoh). The isolated dot image is printed, and after 0.4 seconds after printing, the roll around which the transfer paper (EPSON super fine paper) is wound is pressed with a linear pressure of 1 N / cm, and the dryness of the image is offset from the transfer paper. The image quality was judged from the dot shape.
The transfer paper was My Paper (manufactured by NBS Ricoh), My Recycle Paper (manufactured by NBS Ricoh), and Super Fine Paper (EPSON).

The evaluation results are shown in the following Tables 1 to 3.

Judgment was made in four stages from the state of offset to the transfer paper wound around the roll.
◎: None at all ○: If you look closely △: There is an acceptable range ×: There are many offsets

It was possible to solve the dryness which became worse by using the image improving processing liquid by promoting the water absorption of the transfer paper by the processing liquid. Even with my recycled paper that originally has poor water absorption, as shown in Table 2, the drying property can be improved by the amount of the treatment liquid. In addition, as shown in Table 3 above, there is no difference in the super fine paper that has been subjected to the bleeding prevention process, and there is no need to perform the process.
When the flocculant in the image quality improvement treatment liquid formulation was replaced with calcium nitrate and the same evaluation was performed, the same result was obtained.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus main body 2 ... Paper feed tray 3 ... Paper discharge tray 6 ... Cartridge loading part 10, 10y, 10m, 10c, 10k ... Ink cartridge 33 ... Carriage 34, 34y, 34m, 34c, 34k ... Sub tank 35, 35y , 35 m, 35 c, 35 k... Recording head 42... Recording medium (paper)
DESCRIPTION OF SYMBOLS 43 ... Feed roller 51 ... Conveying belt 64 ... Discharge roller 68 ... Path | route switching means 70 ... 1st process part 80 ... 2nd process part 71, 81 ... Tank 72, 82 ... Supply roller 73, 83 ... Coating roller 74, 84 ... opposite roller 111 ... plasma irradiation device 112 ... corona discharge device 113 ... charging roller device 161 ... vehicle 162 ... color material 163 ... ink droplet 164 ... recording medium (paper) 165 ... image quality improvement processing liquid

JP 2006-205465 A JP 2001-301138 A Japanese Unexamined Patent Publication No. 64-9279

Claims (11)

In an image forming apparatus for ejecting an ink composition containing at least a colorant using an ink jet recording unit and forming an image on a recording medium,
A first processing section for promoting water absorption of the recording medium;
A second processing section for applying to the recording medium an image quality improving treatment liquid containing a flocculant for aggregating the ink composition;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the first processing unit is disposed upstream of the second processing unit in a conveyance path of the recording medium.   The image forming apparatus according to claim 1, wherein the first processing unit includes a processing liquid applying device that applies a hydrophilic treatment liquid.   The image forming apparatus according to claim 1, wherein the first processing unit includes one of a plasma irradiation device, a corona discharge device, and a charging roller device.   The image forming apparatus according to claim 1, wherein the first processing unit includes an adjusting unit that adjusts a degree of processing for promoting water absorption of the recording medium.   6. The image forming apparatus according to claim 1, further comprising switching means for switching presence / absence of processing in the second processing section.   The flocculant contained in the image quality improving treatment liquid applied in the second processing section is one or more selected from polyvalent metal salts, organic acids, and polyamines. The image forming apparatus according to claim 6. In an image forming method of forming an image on a recording medium by discharging an ink composition containing at least a coloring material using an ink jet recording unit,
In the first processing unit that promotes the water absorption of the recording medium, after promoting the water absorption of the surface of the recording medium, an image quality improving treatment liquid is applied in the second processing unit, and then ink is added according to the image data. An image forming method comprising forming an image by discharging a composition.   The image forming method according to claim 8, wherein the degree of processing by the first processing unit that promotes water absorption of the recording medium is adjusted by information input according to the type of the recording medium.   Only when the image quality improving treatment liquid is applied in the second processing section, the water absorption promoting process is performed in the first processing section, and when the image quality improving processing liquid is not applied, the hydrophilic treatment is not performed. The image forming method according to claim 8. A pre-processing apparatus that performs processing of a recording medium before forming an image on the recording medium by discharging an ink composition containing at least a coloring material using an inkjet recording unit,
A first processing section for promoting water absorption of the recording medium;
A second processing section for applying to the recording medium an image quality improving treatment liquid containing a flocculant for aggregating the ink composition;
A pre-processing apparatus for a recording medium, comprising: