JP2006110987A - Ink jet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an environmental-measure-conscious ink jet recording apparatus which can reduce generation of problems in the apparatus due to mist even under the condition that a large amount of mist is generated during ink jet recording and can prolong the life of a mist collecting means. <P>SOLUTION: The ink jet recording apparatus records an image on a recording medium by ejecting at least ink droplets from the nozzle of a recording head. The ink jet recording apparatus has a mist collecting means for collecting mist that does not impact on the recording medium and a catalytic decomposing means for decomposing organic components in the mist by a catalyst. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus that performs recording by discharging ink droplets from a recording head onto a recording medium.

  In recent years, the spread of color documents in offices is remarkable, and various output devices have been proposed. In particular, low-priced inkjet recording apparatuses that can be miniaturized are used in various output devices.

  In an ink jet recording apparatus including an ink jet recording head that discharges ink droplets from nozzles and records on recording paper (recording medium), ink mist (mist) is generated. The ink mist is a micro droplet separated from the final region of the ink droplet when ejecting the ink droplet from the nozzle, or a micro droplet generated by rebound after the ink droplet collides with the recording paper. There is a problem that the ink mist irregularly moves along a path different from the ink droplets that land on the recording paper, and is scattered in the ink jet recording apparatus, thereby contaminating the recording paper or the ink jet recording apparatus. .

  Recently, as a technique for improving the water resistance of images and suppressing bleeding between different colors to improve image quality, a head that discharges treatment liquid containing a substance that insolubilizes and aggregates the colorant in the ink is separated from ink discharge. Although a proposed machine configuration has been proposed (see, for example, Patent Documents 1 and 2), satellite components (associated with main droplets) that are formed along with the main droplets when droplets are ejected in association with such high speed and high image quality (see FIG. Ink and processing liquid generated by rebounding ink droplets on the recording medium and the recording medium adhere to the linear encoder for detecting the position information of the droplet discharge port and the carriage, resulting in ejection failure and position detection failure. It has become a big problem as a cause of troubles such as.

  For these problems, a cover plate is provided in the vicinity of the discharge port, and a method of controlling the mist adhering surface by rebounding with an air flow generated by scanning (for example, see Patent Document 3) or a reaction liquid discharge head and an ink discharge head. A method for reducing the mixing of ink and processing liquid by separating the relative distance (see, for example, Patent Document 4) has been proposed.

However, with these methods alone, sufficient effects cannot be obtained when the amount of mist generation is large, such as a printer equipped with a plurality of ejection openings over the entire width of the high-speed, large-volume printing and recording area, etc. The problem with mist collection has not been solved.
JP-A-8-72234 Japanese Patent Laid-Open No. 8-281931 JP-A-9-216352 JP 2000-141713 A

The object of the present invention is to solve the above-mentioned problems of the prior art.
That is, the present invention can reduce the occurrence of troubles in the apparatus due to mist even under conditions where a large amount of mist is generated during ink jet recording, and can extend the life of the mist collecting means as well as environmental measures. An object of the present invention is to provide an ink jet recording apparatus that takes into account the above.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1> An inkjet recording apparatus that records an image on a recording medium by discharging at least ink droplets from a nozzle of a recording head,
An ink jet recording apparatus comprising: a mist collecting unit that collects mist that has not landed on the recording medium; and a catalyst decomposing unit that decomposes an organic component in the mist with a catalyst.

<2> The inkjet recording apparatus according to <1>, wherein the catalyst is an optical semiconductor catalyst.

<3> The inkjet recording apparatus according to <1>, wherein the mist collecting unit includes an air suction unit.

<4> The inkjet recording apparatus according to <1>, wherein the mist collecting unit includes a collector that collects mist.

<5> The inkjet recording apparatus according to <4>, wherein the collector includes the catalyst.

<6> The inkjet recording apparatus according to <1>, wherein the catalyst decomposition unit includes a light irradiation unit.

<7> The inkjet recording apparatus according to <1>, wherein the recording head includes a nozzle over the entire width of the recording region.

<8> A droplet of a treatment liquid containing at least a component that insolubilizes, aggregates, and / or thickens the ink droplet in addition to the ink droplet is ejected from the nozzle of the recording head < 1>.

  According to the present invention, it is possible to reduce the occurrence of troubles in the apparatus due to mist even under conditions where a large amount of mist is generated during ink jet recording, and it is possible to extend the life of the mist collecting means and to take environmental measures. It is possible to provide an inkjet recording apparatus that takes into account the above.

Hereinafter, the present invention will be described in detail.
The present invention is an ink jet recording apparatus for recording an image on a recording medium by discharging at least ink droplets from a nozzle of a recording head, the mist collecting means for collecting mist that has not landed on the recording medium, And a catalytic decomposition means for decomposing an organic component in the mist with a catalyst.

  That is, according to the configuration of the present invention, not only the mist generated during ink jet recording can be recovered, but also organic components in the recovered mist can be decomposed in the apparatus, so that high speed and high image quality can be achieved. Accordingly, even if a large amount of mist is generated in ink jet recording, the mist can be stably recovered over a long period of time, and the occurrence of ejection failure and image quality failure can be prevented.

Hereinafter, the ink jet recording apparatus of the present invention will be specifically described with reference to the drawings.
FIG. 1 shows a main part of an ink jet printer as an example of the ink jet recording apparatus of the present invention.

This ink jet printer is provided with a fixed recording head 20, and the recording head 20 includes five heads 10. The nozzle surfaces 10a to 10e (see FIG. 2) provided with nozzle rows (not shown) of the head 10 are mounted so as to face the recording paper (recording medium) 40. The nozzle rows on the nozzle surfaces 10a to 10e are arranged over the entire width of the recording paper 40 in the direction of arrow B (the entire width of the recording area), and the paper conveying belt 32 in which the recording paper 40 is stretched between two rolls 30 and 31. As a result, ink droplets are ejected according to image information onto the recording paper 40 conveyed from the recording head 20 at the same time as being conveyed in the direction of arrow A, thereby recording an image on the recording paper 40.
Note that the recording head in the present invention is not limited to the above, but may be a recording head that scans in the width direction of the recording paper 40 as will be described later.

The ink jet printer shown in FIG. 1 uses a two-component ink set configured to include ink ejected as ink droplets and a treatment liquid having an action of aggregating the pigment of the ink. However, the present invention includes a mode in which only ink droplets that do not use the treatment liquid are ejected. Details of the ink and the treatment liquid will be described later.
In this example, the recording paper 40 is used as the recording medium. However, the recording paper 40 is not limited to this and may be a film or an OHP sheet. The recording paper 40 may be a roll or a strip, and is not limited.

  A recording body 51 that collects mist and a black light (light irradiation means) 52 that irradiates the collection body 51 with near-ultraviolet light on the downstream side (right side in the drawing) of the recording head 20 in the recording paper conveyance direction. The mist collection | recovery means 50 provided with these is provided.

  FIG. 2 is a side view of the main part of the ink jet printer shown in FIG. 1 as viewed from the axial direction of the rolls 30 and 31. 2 shows the recording head 20 shown in FIG. 1 and the nozzle surfaces 10a, 10b, 10c, 10d, and 10e of the recording head 20 that are arranged facing the inner side of the drawing in the nozzle surface. Only the transporting means for transporting in one direction in the direction orthogonal to the nozzle row (not shown) and the mist collecting means are shown, and the other configurations are omitted. In FIG. 2, 16 is a recording head body portion, 30 and 31 are rolls, 32 is a paper conveying belt, 40 is a recording medium, 50 is a mist collecting means, and other symbols and symbols are shown in FIG. It is the same as that.

  Conveying means for conveying the recording medium 40 in a state of facing the nozzle surfaces 10 a to 10 e is provided on the nozzle surfaces 10 a to 10 e side of the recording head 20, and this conveying means is upstream in the air flow direction F. , A roll 31 positioned downstream in the airflow direction F, and an endless paper transport belt 32 stretched around these two rolls 30, 31, and the paper is driven by driving means (not shown). The conveyor belt 32 can rotate in the direction of arrow R.

  Here, the recording medium 40 is fed by a sheet supply unit (not shown) on the outer peripheral surface of the sheet conveying belt 32 on the side where the recording head 20 is disposed on the roll 30 side. It is conveyed from the roll 30 side to the roll 31 side by rotation in the direction. In this conveyance process, various printing liquids corresponding to image information are appropriately ejected from the nozzle rows of the nozzle surfaces 10a to 10e onto the surface (front surface) of the recording medium 40 on the recording head 20 side. Is formed (printed), and the recording medium 40 after the image is formed is discharged from the roll 31 side to the outside of the apparatus.

  The nozzle row only needs to be composed of a plurality of nozzles arranged in series for discharging the same printing liquid. Further, the printing liquid discharged from the nozzle array is supplied from a printing liquid supply source such as an ink tank provided on the upper part of the recording head 20, for example. As a method for ejecting the printing liquid, a known method can be used. For example, a so-called piezo ink jet method using a piezoelectric element or a so-called thermal ink jet method in which droplets are formed by applying thermal energy to perform recording can be cited. it can.

  In addition, two or more nozzle rows may be provided in parallel with each other on one nozzle surface. For example, when four nozzle rows (four nozzle surfaces) are provided, cyan, magenta, yellow, and black ink can be ejected from each nozzle row, and five nozzle rows are provided. In addition to the cyan, magenta, yellow, and black inks, the processing liquid can be discharged from each nozzle row.

  In the example shown in FIG. 2, for example, the nozzle row provided on the nozzle surface 10a is the processing liquid, the nozzle row provided on the nozzle surface 10b is black ink, the nozzle row provided on the nozzle surface 10c is cyan ink, and the nozzle surface. The nozzle row provided in 10d can discharge magenta ink, and the nozzle row provided in the nozzle surface 10e can discharge yellow ink.

  In such a configuration, when the recording medium 40 is transported, the same air flow (in the direction of arrow F) as the recording medium 40 is transported between the recording medium 40 and the nozzle surfaces 10 a to 10 e of the recording head 20. appear. In addition to ejecting ink and processing liquid from the nozzle array during printing, mist (droplets that did not land on the recording medium) is generated in addition to the main droplets that contribute to image formation (droplets that land on the recording medium). Resulting in.

  However, in the ink jet printer shown in FIG. 2, since the mist collecting means 50 is provided on the downstream side of the recording head 20 in the airflow direction (arrow F direction), the generated mist is efficiently collected and recorded. Deterioration of the image quality of the image formed on the surface of the medium 40, contamination of the ink jet recording apparatus such as the nozzle surfaces 10a to 10e and the outer peripheral surface of the paper conveying belt 32 due to mist adhesion / accumulation, and secondary troubles (discharging) Defects etc.) can also be prevented.

  In other words, the mist generated below the nozzle surfaces 10a to 10e in the drawing on the recording paper 40 is sucked into the mist suction port 53 of the mist collecting means 50 along the air flow in the direction of arrow F, and the mist is collected. Proceeds in the direction of arrow G through the means 50 and is then absorbed by the collector 51. The air in which the mist is collected is exhausted in the direction of arrow H from the exhaust port 54 of the mist collecting means 50.

  As described above, there is no particular problem as long as the mist generated in the printing area of the recording head 20 is always efficiently collected by the mist collecting means 50, but as described above, the mechanism for improving the image quality and speeding up. When the amount of mist generated increases due to the above, the collection capacity of the collection body 51 is quickly reduced, and the collection body 51 has to be frequently replaced. This causes internal and external contamination and poor image quality, and further, mist is not collected by the mist collecting means 50 but is discharged to the outside of the apparatus as it is.

In the present invention, in order to cope with the above problem, a catalyst decomposing means for decomposing an organic component in the mist collected by the collector 51 with a catalyst is provided. Thereby, since the collected organic substance component can be decomposed | disassembled one by one, since the collection body 51 can always be refreshed and collection ability does not fall, it can collect | recover mist stably.
Here, the organic component in the mist means not only an organic solvent contained in the ink but also an organic component containing a vehicle such as a resin component or a dispersant component.

The configuration of the catalyst decomposing means is not particularly limited as long as the catalyst can exhibit a decomposing action, but in the ink jet printer shown in FIG. 2, titanium oxide (TiO ₂ ), which is a photo semiconductor catalyst, is used as the catalyst in the collector 51. The collector 51 is irradiated with light in the absorption wavelength region of titanium oxide (about 400 nm or less) by a black light (light irradiation means, center wavelength: 352 nm) to decompose the organic component in the collector 51. Yes. Therefore, in this case, the catalyst decomposing means is included in the mist collecting means 50.

The catalyst decomposing means in the present invention is not limited to the above configuration. For example, the organic component absorbed by the collector 51 is separated from the collector 51 by some means in the apparatus, and the separated organic component is separated. You may decompose | disassemble by light irradiation in the decomposition | disassembly space coated with the provided titanium oxide.
Further, the timing and time of the light irradiation are not particularly limited, but for example, it is sufficient to perform light irradiation only during the printing. Details of the collector, catalyst, near infrared irradiation means, etc. will be described later.

  The mist collecting means 50 may be provided with an air suction means so that the air current in the direction of arrow F including the mist can be efficiently sucked. As this air suction means, for example, a configuration in which a fan (not shown) is provided in the exhaust port 54 of the mist collecting means 50 may be employed. When the fan is driven to generate an air flow, mist can be collected more effectively from the suction port 53 facing the print area.

  The installation location of the fan is not particularly limited as long as it is in the ink jet printer, and the exhaust port 54 may be routed to exhaust air from behind the ink jet printer (the back side of the drawing). Further, a plurality of fans may be installed to adjust the suction amount.

The position at which the mist collecting means 50 (including the catalyst decomposing means in some cases) is not particularly limited, but it is preferably installed on the downstream side of the airflow containing mist as shown in FIG.
Regarding the direction of air flow generation during printing, so-called one-pass equipped with a fixed recording head (full line head) having a width substantially equal to the length (printing area) of the recording medium in the direction orthogonal to the conveying direction of the recording medium. In the ink jet recording apparatus of the type, since the recording medium is conveyed in one direction with respect to the nozzle surface, an air flow in which air flows in one direction with respect to the nozzle surface is generated on a macro scale.

On the other hand, in a so-called multi-pass inkjet recording apparatus having a scanning recording head capable of scanning in a direction perpendicular to the conveyance direction of the recording medium, the nozzle surface moves bidirectionally with respect to the surface of the recording medium. Therefore, on a macro scale, an airflow in which air flows in one direction or the opposite direction to the nozzle surface is generated.
That is, the airflow generated on the nozzle surface during printing is formed in a direction parallel to the nozzle surface on a macro scale.

  Accordingly, when the mist collecting means in the present invention is applied to a so-called one-pass type ink jet recording apparatus, if the mist collecting means is fixedly attached to the ink jet recording apparatus so that the mist collecting means is located downstream in the recording medium conveyance direction, Mist generated in the outer nozzle row located downstream in the recording medium conveyance direction can also be efficiently collected.

Further, when the mist collecting means in the present invention is applied to a multi-pass type ink jet recording apparatus, if the mist collecting means is attached to the ink jet recording apparatus so as to be positioned on both sides in the scanning direction of the recording head, the recording head Mist generated in the outer nozzle rows located at both ends in the scanning direction can also be efficiently collected.
When the one-pass method and the multi-pass method are compared, the one-pass method in which the recording head is fixed is more flexible in the place where the mist collecting means is installed because the air flow is not disturbed by the scanning of the recording head. Is preferable because of a large value.

The configuration and shape of the mist collecting means in the present invention are not limited to the examples shown in FIGS. 1 and 2, and may be the configurations and shapes as shown in FIGS. 3 and 4, for example.
FIG. 3 is a schematic diagram showing another example of the configuration / shape of the mist collecting means 60, and FIG. 3 (A) is a view seen from the upper side (upper side in FIG. 1) with respect to the airflow. 3 (B) is a view as seen from the lateral direction (front side in FIG. 1) with respect to the airflow.

  In FIG. 3, 61 represents a collector, 62 represents a black light, and 65 represents a fan. In the configuration shown in FIG. 3, the collector 61 is a windmill type whose surface is coated with titanium oxide as a photocatalyst. By making the collector 61 in such a shape, the mist can be efficiently recovered while constantly changing the position of the collection portion with a wide collection area without disturbing the air flow in the direction of arrow G generated by the fan 65. Can do.

  Further, a black light 62 is provided on the downstream side of the collecting body 61. The black light 62 is turned on at the same time as the collecting body 61 rotates during printing, and the collecting body 61 is irradiated with light. By this light irradiation, titanium oxide on the surface of the collector 61 acts as a catalyst, and decomposes organic components in the mist present on the surface of the collector 61. In this case, since the collector 61 is rotating in a windmill type as described above, the light irradiation is performed uniformly and uniformly, so that the organic component is also efficiently decomposed.

  The mist collecting means 60 shown in FIG. 4 is basically the same as the mist collecting means shown in FIG. 3 except that the arrangement position of the black light 62 is changed. 4A and 4B (the direction in which the mist collecting means is viewed) is the same as in FIGS. 3A and 3B.

  In the mist collecting means 60 shown in FIG. 4, the black light 62 is not located in the airflow direction as shown in FIG. 3, but is installed directly above the collector 61 (above in FIG. 4B). The black light 62 is preferably arranged closer to the collector 61 from the viewpoint of sufficient light irradiation to the titanium oxide of the collector 61, but the black light 62 is in the middle of the airflow as shown in FIG. Then, the black light 62 is contaminated by the mist that cannot be collected by the collector 61, and the amount of irradiation light decreases.

  For this reason, in the configuration shown in FIG. 4, the black light 62 is installed immediately above the collecting body 61, and a cover 64 is provided so that airflow does not enter. With such a configuration, it is possible to irradiate light in a state close to the collector 61, and it is possible to avoid contamination of the black light 62 with mist by continuous use.

Next, the mist collection means, the collector in the catalyst decomposition means, the catalyst, the near infrared irradiation means, etc. will be described.
The collector in the mist collecting means may have a structure in which the airflow (air) cannot pass, but preferably has a structure in which the airflow (air) can pass. In the latter case, the collection body may be composed of, for example, a porous body or fibers. However, the pore size and porosity of the porous body, the void size and fiber diameter between the fibers, etc. are not allowed to pass through the mist, or the inside or the surface of the collecting body in which the mist is composed of the porous body or fibers. It is necessary to have a size that can be collected.

The material constituting the collector is not particularly limited, and known materials such as natural or synthetic resins, rubbers, felt materials, metals, ceramics, paper, etc. can be used, but they are water-absorbing materials. preferable.
However, when a catalyst such as titanium oxide is supported on the collector as described above, the collector itself is preferably a material that is not decomposed by titanium oxide or the like. For example, a metal such as SUS, ceramics, polyester, acrylic Etc. are preferable.

  Further, the shape and form of the collecting body are not particularly limited as long as it is a shape that can be collected without passing through the collecting body when the mist approaches the collecting body. In addition to the shape, a film shape, a fiber shape, or a shape obtained by combining these may be used. Moreover, even when it is set as the said various shape, it is preferable that the collection body has spread over the whole passage area of the airflow in a mist collection | recovery means so that mist can be collected from the sucked airflow without omission.

The catalyst used in the catalyst decomposing means in the present invention is not particularly limited as long as it is a catalyst capable of decomposing organic components, but an optical semiconductor catalyst is used from the viewpoint that the decomposition action is exhibited only by light irradiation and the decomposition efficiency is high. It is preferable.
Here, the photo-semiconductor catalyst generally refers to a substance that is excited by light irradiation to generate electron / hole pairs and reacts adsorbed molecules by diffusion of the electron / hole pairs. The semiconductor catalyst decomposes the organic component adsorbed on the surface by photoexcitation into water and carbon dioxide.

  Examples of the optical semiconductor catalyst include titanium oxide, strontium titanate, zinc oxide, copper, and the like. Among these, titanium oxide is particularly preferable in that it has a large ability to decompose organic matter against light irradiation. Among titanium oxides, anatase-type titanium oxide has higher activity than rutile and amorphous titanium oxide, and is more preferable.

  The degree to which the organic component is decomposed with respect to the same light irradiation amount in the present invention is considered to be proportional to the photoexcitation efficiency of the photocatalytic substance. Generally, the photoexcitation efficiency increases as the particle size of the photo-semiconductor catalyst decreases and the specific surface area increases. , Decomposition ability is increased. The average particle size of the photo-semiconductor catalyst used in the present invention is preferably in the range of 4 to 180 nm, and more preferably in the range of 6 to 30 nm. When the average particle size is less than 4 nm, not only is the production difficult, but handling properties may become a problem. When the average particle diameter exceeds 180 nm, the activity as a photo semiconductor catalyst may not be sufficient.

Incidentally, the specific surface area is intended to substantially inversely proportional to the average particle size, in the present invention is preferably in the range of 9~350m ² / g, and more preferably in the range of 50~260m ² / g .
Moreover, the said optical semiconductor catalyst may be used independently, and 2 or more types of optical semiconductor catalysts may be mixed and used for it.

  When using the photo-semiconductor catalyst, the photo-semiconductor catalyst must be fixed to the surface of the substrate by some method, whether it is supported on the collector as described above or in the decomposition space. I must. As the immobilization method, various methods such as coating using a binder resin, high-temperature baking, and vapor deposition can be used, but coating using a binder resin is preferable in terms of ease of production.

  The binder resin is not limited as long as it can uniformly disperse the photo semiconductor catalyst, but it should be difficult to decompose with active oxygen due to photo excitation of the photo semiconductor catalyst. From this viewpoint, the binder resin is preferably a fluororesin, a silicone resin, or the like.

  As the coating liquid, a sol slurry obtained by dispersing the photo-semiconductor catalyst having the average particle diameter in water, alcohol, toluene or the like may be used. A dispersed one may be used. Further, the coating liquid can be used by mixing the binder resin and other inorganic components, and can also be used by mixing other binders, surfactants, coupling agents, and the like. .

As a coating method, a normal coating method such as a spray method, a dipping method, or a spin coating method can be used. Moreover, after coating, it may be dried at room temperature or may be heat-dried at 100 to 140 ° C. Furthermore, a protective layer may be formed before the coating to prevent deterioration due to a primer layer for improving adhesion and a photocatalyst.
In addition, it is preferable that the layer thickness of the photo-semiconductor catalyst layer after drying is the range of 0.1-10 micrometers.

  Since the surface of the photo-semiconductor catalyst layer formed in this way is that the photo-semiconductor catalyst directly controls the decomposability of the organic component, if the surface of the photo-semiconductor catalyst is covered with a binder or the like, The photocatalytic action is reduced according to the broken ratio. Therefore, it is necessary that the photo-semiconductor catalyst is exposed on the outermost surface of the charging member at a certain ratio, and the ratio is preferably 50% or more as an area ratio in the entire surface.

  The light irradiation means in the present invention is necessary particularly when a photocatalyst such as the above-mentioned photo-semiconductor catalyst is used as a catalyst. As the light irradiation means, since the wavelength range of light to be photoexcited varies depending on the photocatalytic substance, it is necessary that the light to be irradiated includes a wavelength at which a photocatalyst such as the photo-semiconductor catalyst is excited.

  Since most of the exemplified photo-semiconductor catalysts have an absorption wavelength region at a wavelength of 400 nm or less, the light irradiation means in the present invention is preferably one that can irradiate ultraviolet light from near-ultraviolet light of 400 nm or less. . As such light irradiation means, a xenon lamp, a high-pressure mercury lamp, a black light, a sterilization lamp, or the like can be used.

In addition, in order to obtain a sufficient decomposition efficiency in the short time of the light irradiated as an optical intensity, preferably in the range of 0.01~10mJ / cm ² · s, the range of 0.2~1mJ / cm ² · s More preferably.

Next, the ink and the treatment liquid that can be used in the present invention will be described.
As the printing liquid discharged from the nozzles of the recording head, it is preferable to use a colored ink containing at least a pigment, a water-soluble solvent, and water, and a treatment liquid having an action of aggregating the pigment of the ink. In this embodiment, as described above, the treatment liquid is used separately from the ink, but may be used as an ink (for example, yellow ink) by containing a pigment.

The ink includes at least a pigment, a water-soluble solvent, and water.
As the pigment, any of organic pigments and inorganic pigments can be used. Examples of black pigments include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. In addition to black, cyan, magenta, and yellow primary pigments, specific color pigments such as red, green, blue, brown, and white, metallic luster pigments such as gold and silver, colorless or light color extender pigments, plastic pigments, etc. May be used. In addition, a newly synthesized pigment may be used for the present invention.

Specific examples of black pigments include Raven7000, Raven5750, Raven5250, Raven5000 ULTRAII, Raven3500, Raven2000, Raven1500, Raven1250, Raven1200, Raven1190, Raven1125, Raven1125, Raven1170, Raven1125
Regal 400R, Regal 330R, Regal 660R, Mogul L, Black Pearls L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400 (manufactured by Cabot Corporation)
Color Black FW1, Color Black FW2, Color Black FW2V, Color Black 18, Color Black FW200, Color Black S150, Color Black S160, Color Black S160, Color Black 35P, PrintP35P, Color Black SFW, Color Black S160, Color Black S160, Color Black S160, Color Black Black 5, Special Black 4A, Special Black 4 (manufactured by Degussa),
No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (Mitsubishi Chemical Corporation)
However, it is not limited to these.

For cyan, C.I. I. Pigment Blue-1, -2, -3, -15, -15: 1, -15: 2, -15: 3, -15: 4, -16, -22, -60, and the like. It is not limited.
For magenta color, C.I. I. Pigment Red-5, -7, -12, -48, -48: 1, -57, -112, -122, -123, -146, -168, -184, -202, and the like. It is not limited.
For yellow, C.I. I. Pigment Yellow-1, -2, -3, -12, -13, -14, -16, -17, -73, -74, -75, -83, -93, -95, -97, -98, -114, -128, -129, -138, -151, -154, and the like, but are not limited thereto.

  A pigment that can be self-dispersed in water can also be used as the pigment. A pigment that can be self-dispersed in water is a pigment that has many water-solubilizing groups on the pigment surface and can be stably dispersed in water without the presence of a polymer dispersant. Specifically, for example, by applying a surface modification treatment such as acid / base treatment, coupling agent treatment, polymer graft treatment, plasma treatment, oxidation / reduction treatment, etc. to a normal so-called pigment, A dispersible pigment is obtained.

  As pigments that can be self-dispersed in water, in addition to pigments that have been surface-modified to the above pigments, Cab-o-jet-200, Cab-o-jet-300, IJX-253, manufactured by Cabot Corporation, Commercially available self-dispersing pigments such as IJX-266, IJX-444, IJX-273, IJX-55, Microjet Black CW-1, CW-2 manufactured by Orient Chemical Co., etc. can also be used.

  The pigment is used in the range of 0.5 to 20% by mass, preferably 1 to 10% by mass, based on the ink mass. When the amount of pigment in the ink is less than 0.5% by mass, a sufficient optical density may not be obtained, and when the amount of pigment is more than 20% by mass, the ink ejection characteristics are unstable. There was a case.

  A polymer dispersant may be added to the ink to disperse the pigment. In addition, a polymer dispersant may be added as a polymer substance when a pigment that can be self-dispersed in water is used. As the polymer dispersant, a nonionic compound, an anionic compound, a cationic compound, an amphoteric compound and the like can be used. For example, a copolymer of a monomer having an α, β-ethylenically unsaturated group can be used.

  Specifically, as a monomer having an α, β-ethylenically unsaturated group, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid mono Ester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bismethacryloxyethyl phosphate, methacryloxyethyl phenyl acid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, styrene, α -Styrene derivatives such as methylstyrene and vinyltoluene, vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylate, acrylic acid Glycol ester, methacrylic acid alkyl esters, methacrylic acid phenyl ester, methacrylic acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl esters, maleic acid dialkyl ester and the like.

  A copolymer obtained by copolymerizing a single monomer or a plurality of monomers having the α, β-ethylenically unsaturated group is used as a polymer dispersant. Specifically, polyvinyl alcohol, polyvinyl pyrrolidone, styrene-styrene sulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer. Polymer, vinyl naphthalene-methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, alkyl acrylate ester-acrylic acid copolymer, alkyl methacrylate-methacrylic acid, styrene-alkyl methacrylate-methacrylic acid copolymer Examples thereof include a polymer, a styrene-alkyl acrylate ester-acrylic acid copolymer, a styrene-methacrylic acid phenyl ester-methacrylic acid copolymer, and a styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer.

  The polymer dispersant is preferably added in the range of 0.1 to 3% by mass with respect to the ink. When the amount added exceeds 3% by mass, the ink viscosity increases and the ink ejection characteristics sometimes become unstable. On the other hand, when the addition amount was less than 0.1% by mass, there was a case where the dispersion stability of the pigment was lowered. More preferably, it is 0.15-2.5 mass% as addition amount as a polymer dispersing agent, More preferably, it is 0.2-2 mass%.

  Examples of the water-soluble organic solvent contained in the ink include polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, and sulfur-containing solvents. Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, and glycerin. Examples of polyhydric alcohol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and diglycerin. Examples include ethylene oxide adducts. Examples of nitrogen-containing solvents include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, and triethanolamine. Examples of alcohols include alcohols such as ethanol, isopropyl alcohol, butyl alcohol, and benzyl alcohol. Thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide and the like. In addition, propylene carbonate, ethylene carbonate, or the like can also be used.

  It is preferable to use at least one water-soluble organic solvent. The content of the water-soluble organic solvent is 1 to 60% by mass, preferably 5 to 40% by mass. When the amount of the water-soluble organic solvent in the ink is less than 1% by mass, a sufficient optical density may not be obtained. Conversely, when the amount is more than 60% by mass, the ink viscosity increases. In some cases, the ink ejection characteristics become unstable.

  The ink may contain a surfactant. As the surfactant, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used. An anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant Any of the agents may be used. Moreover, the said polymer dispersing agent can also be used as surfactant.

  Among these, a nonionic surfactant is preferable from the viewpoint of dispersion stability of the pigment. From the viewpoint of permeability control, acetylene glycol, oxyethylene adduct of acetylene glycol, polyoxyethylene alkyl ether and the like are particularly preferable.

  The addition amount of the surfactant is preferably less than 10% by mass with respect to the ink, more preferably 0.01 to 5% by mass, and still more preferably 0.01 to 3% by mass. When the addition amount was 10% by mass or more, there were cases where the optical density and the storage stability of the pigment ink were deteriorated.

  In addition, for the purpose of controlling properties such as improving ink ejection properties, the ink includes polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethylcellulose, carboxymethylcellulose, etc., and potassium hydroxide, Alkali metal compounds such as sodium hydroxide and lithium hydroxide, and other pH buffering agents, antioxidants, fungicides, viscosity modifiers, conductive agents, ultraviolet absorbers, chelating agents, etc. Can be added.

  Any treatment liquid may be used as long as it contains a component that aggregates the pigment in the ink. Specifically, for example, for an ink containing a pigment having an anionic group, an electrolyte or a cationic compound may be contained in the treatment liquid. Examples of the electrolyte that can be effectively used in the present invention include alkali metal ions such as lithium ions, sodium ions, and potassium ions, and aluminum ions, barium ions, calcium ions, copper ions, iron ions, magnesium ions, manganese ions, nickel ions, Multivalent metal ions such as tin ion, titanium ion, zinc ion, hydrochloric acid, odorous acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, thiocyanic acid, and acetic acid, oxalic acid, lactic acid, fumaric acid, fumaric acid, citric acid Examples thereof include organic carboxylic acids such as acids, salicylic acid and benzoic acid, and salts of organic sulfonic acids.

  Specific examples include lithium chloride, sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, sodium sulfate, potassium nitrate, sodium acetate, potassium oxalate, sodium citrate, potassium benzoate and the like. Alkali metal salts and 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, thioan Barium acid, calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, calcium salicylate Cium, calcium tartrate, calcium lactate, calcium fumarate, calcium citrate, copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetate, iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, oxalic acid Iron, iron lactate, iron fumarate, iron citrate, magnesium chloride, magnesium bromide, 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, nickel bromide, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate, titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, thiocyanate Examples thereof include salts of polyvalent metals such as zinc acid and zinc acetate.

  On the other hand, examples of the cationic compound include primary, secondary, tertiary and quaternary amines and salts thereof. Specific examples include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, polyamines, etc., for example, isopropylamine, isobutylamine, t-butylamine, 2-ethylhexylamine. , Nonylamine, dipropylamine, diethylamine, trimethylamine, triethylamine, dimethylpropylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, diethanolamine, diethylethanolamine, triethanolamine, tetramethylammonium chloride, tetraethylammonium Bromide, dihydroxyethyl stearylamine, 2-heptadecenyl-hydroxyethyl Imidazoline, lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridinium chloride, diallyldimethylammonium chloride polymers, diallylamine polymers include monoallylamine polymer and the like.

  Preferred electrolytes include aluminum sulfate, calcium chloride, calcium nitrate, calcium acetate, magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium acetate, tin sulfate, zinc chloride, zinc nitrate, zinc sulfate, zinc acetate, aluminum nitrate, monoallylamine heavy Examples thereof include a polymer, a diallylamine polymer, and a diallyldimethylammonium chloride polymer.

  On the other hand, for an ink containing a pigment having a cationic group on the surface, an anionic compound or the like may be contained in the treatment liquid. Examples of the anion compound that can be effectively used in the present invention include organic carboxylic acids or organic sulfonic acids, and salts thereof. Specifically, examples of the organic carboxylic acid include acetic acid, succinic acid, lactic acid, fumaric acid, citric acid, salicylic acid, benzoic acid, and the like, and an oligomer or polymer having a plurality of these basic structures may be used. Examples of the organic sulfonic acid include compounds such as benzene sulfonic acid and toluene sulfonic acid, and oligomers and polymers having a plurality of these basic structures may be used.

In the treatment liquid, the above compounds may be used alone or in combination of two or more. Moreover, as said compound content in a process liquid, 0.1-15 mass% is preferable, More preferably, it is used at 0.5-10 mass%.
The treatment liquid may contain a surfactant in the same manner as the ink. About this surfactant, the thing similar to what was mentioned above is mentioned.

  The ink jet recording apparatus of the present invention may be provided with a maintenance unit for maintaining the recording head in order to maintain / recover the discharge property or the like at the time of non-printing. The maintenance unit generally has at least a cap that receives and collects the printing liquid discharged from the recording head by discharge with a dummy jet or suction using a pump or the like on the inner surface. .

  Further, from the viewpoint of speeding up, the higher the recording medium conveyance speed is, the better. However, when the recording medium speed is too high, the flow of airflow generated on the nozzle surface becomes faster and mist is likely to be scattered. However, according to the present invention, the above-described one-pass inkjet recording apparatus is also provided with the mist collecting means provided with the catalyst decomposing means on the downstream side of the recording head. Also, it is possible to suppress mist scattering. Therefore, even in a high speed region where the recording medium is transported at a speed of 100 mm / s or higher, mist scattering can be suppressed, and image degradation and contamination in the apparatus can be suppressed.

Furthermore, from the viewpoint of high image quality (high definition), it is more preferable that the amount of liquid per drop of the printing liquid ejected from the recording head is small. However, when the ejected droplets become smaller, the generated mist is expected to become finer. In this case, the mist staying property is improved, so that the mist is easily scattered.
However, in the above-described ink jet recording apparatus of the present invention, since the mist collecting means including the catalyst decomposing means is provided on the downstream side of the recording head, the mist is scattered even if the amount of liquid per drop is reduced. Can be suppressed. Therefore, even when the amount of liquid per drop is 10 pl or less, which is suitable for high image quality, it is possible to suppress mist scattering and to suppress image degradation and contamination in the apparatus.

In the present embodiment, the ink jet type ink jet printer has been described. However, the ink jet method is not limited to a thermal ink jet method, a piezo ink jet method, a continuous flow ink jet method, an electrostatic suction ink jet method, or the like.
Furthermore, the ink to be used may be any of water-based ink, oil-based ink, so-called solid ink solid at room temperature, solvent ink, and the like. The coloring material in the ink may be any pigment or dye.

Hereinafter, the present invention will be specifically described with reference to examples.
<Preparation of inkjet ink set>
Appropriate amounts of a colorant solution, a water-soluble organic solvent, a surfactant, ion-exchanged water, and the like were added to obtain a predetermined composition, and the mixed solution was mixed and stirred. The obtained liquid was passed through a 5 μm filter to obtain each desired liquid.

(Inkjet ink set 1)
-Ink 1 (black ink)-
・ Cabojet-300 (carboxylic acid group / Cabot) 4% by mass
Styrene-acrylic acid copolymer (acid value 100 / neutralization degree 95%) 1% by mass
・ Diethylene glycol 15% by mass
・ Thiodiglycol 2.5% by mass
・ Diethylene glycol monobutyl ether 2.5% by mass
・ Acetylene glycol ethylene oxide adduct 0.2% by mass
・ Ion exchange water balance

-Ink 2 (cyan ink)
・ C. I. Pigment Blue 15: 3 (sulfonic acid group) 4% by mass
・ Diethylene glycol 20% by mass
・ Propylene glycol 2.5% by mass
・ Diethylene glycol monobutyl ether 2.5% by mass
・ Acetylene glycol ethylene oxide adduct 1% by mass
-Furancarboxylic acid 1% by mass
・ Sodium hydroxide 0.2% by mass
・ Ion exchange water balance

-Ink 3 (magenta ink)
・ C. I. Pigment Red 122 (sulfonic acid group) 4% by mass
・ Diethylene glycol 15% by mass
・ Triethylene glycol 5% by mass
・ Sulfolane 2.5% by mass
・ Diethylene glycol monobutyl ether 2.5% by mass
・ Acetylene glycol ethylene oxide adduct 1% by mass
・ Ion exchange water balance

-Ink 4 (yellow ink)
・ C. I. Pigment Yellow 128 (sulfonic acid group) 4% by mass
・ Diethylene glycol 20% by mass
・ Diethylene glycol monobutyl ether 5% by mass
・ Acetylene glycol ethylene oxide adduct 1% by mass
・ Ion exchange water balance

-Treatment liquid-
・ Diethylene glycol 25% by mass
・ Magnesium nitrate hexahydrate 5% by mass
・ Acetylene glycol ethylene oxide adduct 1% by mass
・ Ion exchange water balance

<Printing conditions>
For printing, an evaluation prototype thermal ink jet recording apparatus having a full line head as shown in FIG. 1 in which five nozzle surfaces of 600 dpi and 4960 nozzles are arranged for each color is used as a recording head. The inks 1 to 4 and the treatment liquid were loaded in the same order as described above.

In addition, a windmill-shaped titanium oxide coat collector using a ceramic as a base material (titanium oxide particle size: 25 nm, specific surface area: 150 m ² / g, binder resin: fluororesin, titanium oxide coat amount: 50 g / m ² ) A provided mist collecting mechanism A (removable on the downstream side of the recording head of the ink jet recording apparatus) was prepared. On the other hand, a similar mist recovery mechanism B was also prepared except that titanium oxide was not coated as a collector. In addition, a fan for air suction was provided at the exhaust port of these mist collecting means. When this fan was driven, the airflow velocity at the suction port of the mist collecting mechanism was about 20 mm / sec.

Further, the mist collecting mechanism A is provided with a black light as a light irradiation means at a position above the collecting body as shown in FIG. 4B, and the collecting body emits light with a light intensity of about 1 mJ / cm ² · s. I was able to irradiate. The light irradiation was set to be performed only during the printing operation of the apparatus.

As a recording medium, multi-ace paper (manufactured by Fuji Xerox Co., Ltd.) or the like was used. The discharge amount is about 10 pl, the ink shot amount is about 0.03 ml / m ² , the mass ratio of the processing liquid to the ink for forming pixels (processing liquid / ink) is 1/2, and printing is 5% for each color of A4. In the coverage pattern, the printing speed (paper conveyance speed) was set to 105 mm / sec. Printing was performed under a general environment (temperature: 23 ± 0.5 ° C., humidity: 55 ± 5% RH).

<Examples and comparative examples>
Under the above printing conditions, a printing test was conducted on up to about 60,000 sheets for each of the following three specifications of the inkjet recording apparatus.
(1) Printing is performed by mounting the mist collecting mechanism A and driving the fan (specifications of the present invention).
(2) Printing is performed by installing the mist collecting mechanism B and driving the fan.
(3) Printing without installing a mist collecting mechanism.

In addition, in printing of each specification, an HG coated paper (manufactured by Fuji Xerox Co., Ltd.) is applied to the back surface of the cover of the ink jet recording apparatus, and the optical density meter (manufactured by X-Rite, X-Rite 540) is used for every 1000 prints. The optical density OD _PV of the coated paper was measured. Then, the change from the initial optical density OD _IN (0.1 in this example) was examined by ΔOD represented by the following formula (1).
ΔOD = OD _PV −OD _IN (1)
Changes in ΔOD with respect to the number of printed sheets are collectively shown in FIG.

  As shown in FIG. 5, when there is no conventional mist collection mechanism (specification (3) above) and when a normal mist collection mechanism is provided (specification (2) above), the initial ΔOD The increase is improved, but the increase in the number of printed sheets cannot be suppressed. In contrast, it can be seen that the mist recovery mechanism (specification (1)) provided with the catalyst decomposing means of the present invention can suppress an increase in ΔOD up to a high number of printed sheets.

It is the schematic which shows an example of the principal part of the inkjet recording device of this invention. 1 is a schematic diagram illustrating an example of a main part of an ink jet recording apparatus of the present invention. It is a schematic diagram which shows an example of arrangement | positioning form and shape of a mist collection | recovery means and a catalyst decomposition | disassembly means, (A) is the figure seen from the upper direction of the flow direction of airflow, (B) is seen from the horizontal direction of the flow direction of airflow. It is a figure. It is a schematic diagram which shows another example of arrangement | positioning form and shape of a mist collection | recovery means and a catalyst decomposition | disassembly means, (A) is the figure seen from the upper direction of the flow direction of airflow, (B) is the horizontal direction of the flow direction of airflow. It is the figure seen from. FIG. 6 is a diagram illustrating a relationship between the number of printed sheets and ΔOD (dirt).

Explanation of symbols

10 Head 10a, 10b, 10c, 10d, 10e Nozzle surface 16 Recording head main body portion 20 Recording head 30, 31 Roll 32 Paper transport belt 40 Recording medium 50, 60 Mist collection means 51, 61 Collection body 52, 62 Black light (light Irradiation means)
53 Suction port 54 Exhaust port 64 Cover 65 Fan (air suction means)

Claims (8)

An inkjet recording apparatus that records an image on a recording medium by discharging at least ink droplets from a nozzle of a recording head,
An ink jet recording apparatus comprising: a mist collecting unit that collects mist that has not landed on the recording medium; and a catalyst decomposing unit that decomposes an organic component in the mist with a catalyst.   The inkjet recording apparatus according to claim 1, wherein the catalyst is a photo semiconductor catalyst.   The inkjet recording apparatus according to claim 1, wherein the mist collecting unit includes an air suction unit.   The inkjet recording apparatus according to claim 1, wherein the mist collecting unit includes a collector that collects mist.   The inkjet recording apparatus according to claim 4, wherein the collector includes the catalyst.   The inkjet recording apparatus according to claim 1, wherein the catalyst decomposition unit includes a light irradiation unit.   The inkjet recording apparatus according to claim 1, wherein the recording head includes a nozzle over the entire width of the recording area.   2. A droplet of a treatment liquid containing at least a component that insolubilizes or aggregates and / or thickens the ink droplet, in addition to the ink droplet, is ejected from a nozzle of the recording head. The ink jet recording apparatus described.