JP2006240164A - Inkjet recording head and inkjet recorder using the head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute an ejection opening-formed face wherein decrease in precision of ejection is prevented in an inkjet recording head equipped with ejecting parts capable of making ejection by switching a first ink and a second ink with different characteristics. <P>SOLUTION: Whether the ejection opening-formed face is made a non water-repellent face or a water-repellent face is selected by taking suitability to not only each of the first ink and second ink but the mixture of them into account. For example, when a photo black ink and a mat black ink are switched to be used, the non water-repellent face 1001 is employed as the ejection opening-formed face. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording head and an ink jet recording apparatus using the head.

  In general, an ink jet recording apparatus includes a carriage on which a recording head, which is a recording unit, can be mounted, a transport unit that transports a recording medium, and a control unit that controls these. Then, while ejecting ink as, for example, droplets from a plurality of ejection openings formed in the recording head, the carriage is serially scanned in the main scanning direction, and the recording medium is set in a sub-scanning direction perpendicular to the main scanning direction. Images are sequentially formed on a recording medium by intermittently conveying them in an amount.

  This recording method is a recording method in which ink is ejected in accordance with a recording signal and the ejected ink is landed on a recording medium, and recording is performed. Therefore, many recording apparatuses such as printers, copiers, facsimiles, word processors and the like to which the ink jet recording method is applied have been put into practical use. In addition, since this recording method does not require a complicated mechanism for implementation, it is relatively easy to reduce the size and color of the apparatus. In particular, in recent years, a color recording apparatus using a plurality of colors of ink has been used. Many applied products have been put into practical use. In such an ink jet recording apparatus, there are various methods for ejecting ink. For example, as a typical example, a heating element such as an electrothermal conversion element is provided in an ink path in the vicinity of an ejection port for ejecting ink, and film boiling occurs in the ink by the heat energy generated by the heating element. There is a method of discharging ink by the rapid generation pressure of bubbles due to film boiling.

  FIG. 13 is a conceptual view showing a general ink jet recording head employed in the above-described serial scan type ink jet recording apparatus from the direction in which ink is ejected. Here, a plurality of ejection units 205 capable of ejecting inks having different color tones (including colors and densities) are juxtaposed on the recording head 203 in the main scanning direction indicated by the arrows. In each of the ejection units 205, 1280 ejection ports (nozzles) 207 are arranged at a pitch of about 20 μm, and a configuration capable of recording a color image with a recording density of 1200 dpi (dot / inch; reference value) at high speed. It has become. In addition, the site | part of the discharge part in which the discharge outlet was formed is called a face surface below.

  Here, as the ink to be used, there are generally an ink containing a pigment component and an ink containing a dye component (hereinafter referred to as pigment ink and dye ink, respectively). Dye inks are excellent in color developability but inferior in image fastness, while pigment inks are excellent in image fastness and are difficult to fade even when the printed matter is left outdoors for a long time. Recently, inkjet recording devices have been used in many applications, especially pigment inks with high image robustness, which are used to create office-use printers that require document reliability and large format posters for outdoor exhibitions. It is often applied to printers. As described above, ink having an appropriate property is used in accordance with various forms and uses of the recording apparatus.

  It is known that ink adheres to the face surface of the recording head. This is because a large amount of small ink droplets (hereinafter referred to as “mist”) is ejected in addition to the original ink droplets (main droplets) for recording purposes when ink is ejected from the nozzles. Since the mist generated in a large amount has a small mass, the mist drifts in the space between the recording head and the recording medium, and may come back and adhere to the face surface of the recording head. There is also a mist in which a main droplet has landed on the surface of the recording medium, but a part of the droplet rebounds and reattaches to the face surface.

  Such mist stains the face surface, and particularly when it adheres around the ejection port, pulling the main droplet from which the adhered ink is ejected reduces the ink ejection direction from the nozzle (this phenomenon is It is sometimes called "Yoroi" because it is called. Further, in severe cases, non-ejection may occur.

  It is known that the adverse effect caused by the mist adhering to the face surface, that is, the decrease in ejection accuracy, differs depending on the color material in the ink. For example, in dye ink, ink adhering to the vicinity of the face surface is relatively easy to remove. On the other hand, in the case of pigment ink, it has been found that ink attached to the face surface is relatively difficult to remove.

  Measures for appropriately determining the properties of the face surface may be employed against such stains on the face surface caused by ink. For example, Patent Document 1 discloses a technique for forming a hydrophilic face surface for a nozzle that discharges a pigment. Further, for example, in Patent Document 2, a nozzle that discharges dye ink is used to make the face surface evenly wetted by applying hydrophilic treatment to the face surface of the nozzle that discharges pigment ink. A technique is disclosed in which the face surface is kept clean by making it a highly water-repellent face surface. For example, Patent Document 3 discloses a technique for changing the shape of the water-repellent region and the shape of the hydrophilic region on the face according to the difference in the type of ink.

  Here, in order to obtain a recording head having a water-repellent face surface, it is common to perform a process of coating the face surface with a water repellent. In addition, a recording head having a hydrophilic face surface can be made as a non-water-repellent face surface by directly applying the material constituting the nozzle or the discharge section, or actively subjected to a hydrophilic treatment on the face surface. There is what I did.

Japanese Patent Laid-Open No. 11-334074 JP 2004-147553 A Japanese Patent Application No. 8-39805

  Recently, with the diversification of uses of ink jet recording apparatuses, the inks used have also diversified. For example, with regard to pigment inks, glossiness is also achieved for inks that can achieve high glossy recording on highly glossy recording media (glossy paper) and for recording media that do not have glossiness (matte paper). There are inks that achieve recording without any problems. There are also pigment inks that are particularly excellent in color developability and pigment inks that are particularly excellent in fastness. Each of these various inks has not only different components such as a color material, a solvent, and an activator in the ink, but also various dispersion forms of the color material in the ink. For example, the ink that achieves the above-mentioned high glossy recording forms a stable dispersion state in the ink by covering the pigment color material with a polymer dispersing material, and the ink that realizes the recording without glossiness is In general, a stable dispersion state is formed by the functional group of the pigment itself.

  Such diversification of ink leads to the necessity of an ink jet recording head and an ink jet recording apparatus that are optimal for each ink. That is, for example, as described above, the face surface of the recording head desirably has a form suitable for each ink (whether it has water repellency or hydrophilicity).

  In addition, with such diversification of inks, products that can eject a plurality of types of ink using a single nozzle row are commercially available. In this case, any ink can be selectively ejected by replacing ink ejected from one nozzle row as necessary. For example, ink that realizes high glossy recording on the above-mentioned glossy paper (such ink is suitable for photographic images, and hereinafter referred to as “photo ink”), and matte paper without glossiness As the ink suitable for the ink (hereinafter referred to as “matte ink”), one of the two types of ink may be selected according to the type of the recording medium selected as the recording target. There is no need to prepare. That is, one nozzle row can be used for these two types of ink. In such an ink exchange configuration (hereinafter referred to as an “ink exchange system”), the number of nozzle rows of the print head can be reduced, thereby reducing the cost and size of the print head and thus the printing apparatus main body. Is possible. In order to apply such an ink exchange system, it is considered desirable to adopt a configuration of a recording apparatus and a head in a form suitable for both inks.

  However, as a result of intensive studies, the present inventor has found that it is not sufficient to adopt such a configuration suitable for both inks. Next, the reason will be described.

  The inventor has tried to apply a photo glossy ink having a strong gloss and a matte black ink suitable for matte paper as the black ink used in the ink exchange system. Since both of these two can stably discharge onto a highly water-repellent face surface, a discharge surface for these inks that uses a highly water-repellent face surface was used. . However, when the two inks were replaced and used, the water-repellent performance of the face surface was significantly deteriorated, and the ink ejection performance was severely distorted for both inks.

  As described above, the present inventor has a problem that cannot be dealt with by simply adopting a head and a recording apparatus suitable for each ink for a new system called an ink exchange system in a situation where ink is diversified. I found out.

  Accordingly, an object of the present invention is to provide a configuration that can always exhibit desirable ink ejection performance for an ink replacement system.

Therefore, the present invention provides an ink jet recording head having an ejection unit that can eject by exchanging the first ink and the second ink having different characteristics.
The portion of the discharge portion where the ink discharge port is provided corresponds to all of the first ink, the second ink, and the mixed ink obtained by mixing the first ink and the second ink. Thus, the discharge characteristic is maintained.

Here, regarding at least one ink of the first ink, the second ink, and a mixed ink obtained by mixing the first ink and the second ink,
In the case where the affinity for the water repellent surface is relatively high, the part is configured not to exhibit water repellency, or
In the case where the affinity for the water-repellent surface is relatively high when evaporation of the solvent occurs, the part is configured not to exhibit water repellency, or
When the surface tension is relatively low, the part can be configured to exhibit water repellency.

  Furthermore, the present invention is an ink jet recording apparatus that performs recording using the ink jet recording head, wherein the first ink and the second ink are switched and selectively supplied to the ejection unit. It is characterized by comprising the following means.

  According to the present invention, in a system in which ink is used after replacement, the suitability for the mixed ink is considered in accordance with the conditions of the first ink, the second ink, and the mixed ink, that is, not only each of the single ink but also the individual ink. By selecting an appropriate face surface configuration, it is possible to maintain discharge accuracy and perform high-quality image recording.

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

(1) Mechanical Configuration of Inkjet Recording Apparatus (1-1) Outline of Apparatus FIG. 1 shows an appearance of an inkjet recording apparatus (hereinafter also referred to as a printer) according to an embodiment of the present invention. This is a so-called serial scan type printer, which forms an image by scanning (main scanning) the recording head in a direction (main scanning direction) orthogonal to the conveyance direction of the recording medium P.

  The configuration of this printer and the outline of the operation during recording will be described with reference to FIG. First, the recording medium P is transported by a paper feed roller 6 driven via a gear by a paper feed motor (not shown). On the other hand, the carriage unit 2 is scanned along a guide shaft 8 extending in a direction orthogonal to the conveyance direction by a carriage motor (not shown) at a predetermined conveyance position. In the course of this scan, the nozzle 7 is caused to perform an ejection operation from an ink ejection port (nozzle) of a recording head (described later) that is detachably attached to the carriage unit 2 at a timing based on a position signal obtained by the encoder 7. Record a certain bandwidth corresponding to the array range. Thereafter, the recording medium is transported and recording is performed for the next bandwidth. In such a printer, there is a case where the recording medium is transported for the bandwidth between each scan, and if necessary, the transport for the bandwidth is not performed for each scan, and the transport is performed after performing a plurality of scans. In addition, after recording data thinned out by a predetermined mask every scan, paper feeding around 1 / n band is performed, and scanning is performed again. There is a case where a method of completing an image (so-called multi-pass recording) is performed by a plurality of scans and conveyances with different nozzles involved in recording.

  A flexible wiring board 19 for supplying a signal pulse for ejection driving, a head temperature adjustment signal, and the like is attached to the recording head. The other end of the flexible substrate is connected to a control circuit (described later) having a control circuit for executing control of the printer. As will be described later with reference to FIGS. 2 and 5, the recording head mounted on the carriage unit 2 receives ink from an ink tank that stores six colors of ink independently from each other via an ink supply tube 45. Supplied. Further, a recovery system unit (FIG. 7) for performing recovery processing of the recording head is provided in a part of the movable range of the carriage unit 2, for example, at the home position of the recording head.

  A carriage belt can be used to transmit the driving force from the carriage motor to the carriage unit 2. However, instead of the carriage belt, for example, a lead screw that is rotationally driven by a carriage motor and extends in the main scanning direction, and an engagement portion that is provided in the carriage unit 2 and engages with a groove of the lead screw, etc. Other driving methods can also be used.

  The fed recording medium P is nipped and conveyed between a paper feed roller 6 and a pinch roller (not shown) and guided to a recording position on the platen 4 (main scanning area of the recording head). Since the face surface of the recording head is capped in the normal resting state, the cap is opened prior to recording, and the recording head or carriage unit 2 is brought into a scannable state. After that, when data for one scan is accumulated in the buffer, the carriage unit 2 is scanned by the carriage motor 3 and recording is performed as described above.

(1-2) Configuration of Recording Head FIG. 2 is a schematic perspective view showing the recording head mounted on the carriage unit 2 of the printer from the direction in which ink is ejected. Here, the recording head 9 includes inks of different tones (including color and density) in the main scanning direction S, such as black (Bk), light cyan (Lc), cyan (C), light magenta (Lm), and magenta. A plurality of ejection units 11 to 16 capable of ejecting (M) and yellow (Y) inks are juxtaposed. Ink is supplied from the ink introduction unit 23 to each ejection unit via an ink flow path inside the recording head. Ink is introduced into the ink introduction part 23 from a later-described ink tank through a tube.

FIG. 3 is a schematic perspective view of each discharge unit.
Each ejection unit uses, for example, thermal energy that causes film boiling in the ink in response to energization as energy used for ejecting the ink, and heat generated by the heating unit 52 formed at a predetermined pitch. It has a substrate 51 in which two rows are arranged in parallel. An ink supply port 56 that communicates with the ink flow path is provided between the heating unit rows of the substrate 51. For the substrate 51, a member (orifice plate) 54 in which a nozzle 55 corresponding to the heat generating portion 52 and an ink path 59 for supplying ink from the ink supply port 56 corresponding to each of the nozzles 55 are formed. Are joined to form a discharge section.

  In each row, the heat generating portion 52 and the nozzle 55 are arranged with a half pitch shift to achieve a desired recording resolution. Here, the same recording density and the same number of nozzles may be used for each of the ejection units 11 to 16, or different recording densities and the number of nozzles may be used. In this embodiment, 640 nozzles are arranged at a density of about 245 nozzles per cm in the Bk ejection unit 11, and the density of about 490 nozzles per cm for each color in the other color ink ejection units 11-15. 1280 nozzles are arranged.

  FIG. 4 is a schematic longitudinal sectional view of the recording head 9. The recording head 9 has a liquid chamber portion 91 that communicates with the ink tank via a supply tube or the like, which will be described later, and stores the supplied ink. A filter 93 is inserted to prevent bubbles and the like from entering. Here, even if dust or the like smaller than the cross section of the nozzle 52 passes through the filter 93, the possibility of passing through the nozzle is also high. Therefore, in order to prevent the nozzle 52 from being clogged with dust, it is usual that the cross-sectional area of the hole of the filter 93 is designed to be smaller than the cross-sectional area of the nozzle. 95 is a rubber damper, for example, that defines a part of the ink storage space of the liquid chamber portion 93, and absorbs a sudden change in internal pressure (pressure increase, etc.) inside the ink storage space due to environmental changes, Prevent ink from leaking from the nozzles.

  In this example, the heating unit 52 uses a discharge unit that discharges ink in a direction perpendicular to the substrate 51. However, a discharge unit that discharges ink in a parallel direction may be used.

(1-3) Ink Supply System FIG. 5 shows a configuration example of an ink supply system for the recording head or the ejection unit. FIG. 6 is an explanatory diagram showing the internal configuration of the ink supply system for one color. Although FIG. 6 shows a supply system corresponding to black ink, the supply systems for inks of other colors are similarly configured.

  Here, there are mainly two methods for supplying ink to the recording head or ejection unit. One is to mount an ink tank for holding ink on the carriage and to supply ink directly to the recording head. This is a supply method that is widely applied in home printers and printers that are easy to carry because the main unit can be configured relatively simply. The other uses a tube called a supply tube to supply ink by connecting an ink tank arranged at a fixed portion of the apparatus and a recording head mounted on a carriage. Since this does not assume that an ink tank is mounted on the carriage, it is possible to use a relatively large-capacity ink tank, and it is often used in office and professional use printers with a large print volume. In this embodiment, this method is adopted.

  Ink tanks 39Bk, 39Lc, 39C, 39Lm, 39M and 39Y have different black (Bk), light cyan (Lc), cyan (C), light magenta (Lm), magenta (M) and yellow (Y) inks, respectively. Is stored. The ink supply tube 45 connected to each color ink tank has flexibility that can follow the movement (scanning) of the carriage unit 2 or the recording head 9. Reference numeral 46 denotes a joint mounted on the carriage unit 2 together with the recording head. The other end of each supply tube 45 is connected to the joint 46 and has an ink outlet tube 45A coupled to the ink introduction portion 23 of the recording head 9.

  Each ink tank is molded by resin such as PP or PE by injection blow or the like, and is assembled using techniques such as ultrasonic welding, thermal welding, adhesion, and fitting. In FIG. 4, an example in which the tank exterior functions as an ink chamber as it is is illustrated, and the joint rubber 44 is disposed at the bottom thereof, while the hollow needle 43 provided at the end of the supply tube 45 penetrates the joint rubber 44. The ink supply is received by entering the ink chamber. Further, an atmospheric communication pipe 41 is connected to each ink tank through a hollow needle 42, and air for the consumed ink is supplied into the ink chamber through the ink tank, thereby keeping the internal pressure substantially constant. The negative pressure acting on the recording head is generated by a water head difference between the nozzle 52 and the meniscus formed at the opening 48 of the hollow needle 42. In this embodiment, the negative pressure is set to −90 mmAq. A buffer chamber 41 </ b> A is inserted in the atmosphere communication pipe 41. This fulfills the function of absorbing a change in pressure in the ink chamber due to an environmental change or the like so as not to affect the supply tube 45 and thus the recording head 9 side. For example, it functions to temporarily hold ink that overflows from the inside of the ink tank due to expansion of the air in the ink tank.

  Reference numeral 49 shown in FIG. 6 is a valve that is inserted in a communication pipe 45B that connects the hollow needle 43 and the supply tube 45 in the middle of the ink supply path. Closed during transportation.

  Note that the configuration of the ink tank is not limited to the above-described one. For example, the ink tank has an ink bag filled with ink, and the inside is filled with a porous material so as to be impregnated and retained, and the ink discharge of the recording head is performed. A negative pressure for holding the ink meniscus formed at the outlet may be generated. Further, as a form of the tank having such a negative pressure generating mechanism, a flexible bag for storing ink is provided, and the inner volume of the bag is expanded by a spring mechanism or the like provided inside or outside the bag. It may be one that is energized.

(1-4) Recovery System Unit The carriage unit 2 stops at the home position as necessary before or during recording. A recovery system unit including a cap and a wiper blade is disposed near the home position.

  FIG. 7 is a schematic perspective view showing a configuration example of the recovery system unit. The cap 27 is supported by an elevating mechanism (not shown) so as to be movable up and down. In the raised position, for example, capping is performed for each face surface of the three ejection units to protect or recover the suction during a non-recording operation or the like. Can be done. During the recording operation, it is set at a lowered position that avoids interference with the recording head 9, and can receive preliminary ejection by facing the face surface.

  Wiper blades 21 and 22 made of an elastic member such as rubber are fixed to the wiper holder 25. The wiper holder 25 is movable along the guide 24 in the front-rear direction of the drawing indicated by the arrow W (the direction in which the discharge ports are arranged in the discharge unit). When the recording head 9 reaches the home position, the wiper holder 25 moves in the direction of the arrow W, so that wiping is possible. When the wiping operation is completed, the carriage is retracted out of the wiping area and then returned to a position where the wiper does not interfere with the face surface or the like. In this example, there are two wiper blades 21 that perform wiping for each face surface of the three discharge units, and a wiper blade 22 that wipes the entire surface of the recording head 9 including the discharge surfaces of the discharge units 11 to 16. Is provided.

  The suction pump 29 joins the cap 27 to the face surface and generates a negative pressure in a state where a sealed space is formed therein, so that the ink is filled from the ink tank into the recording head or the discharge unit, or the discharge port or It is possible to suck and remove dust, fixed matter, bubbles, etc. existing in the inner ink path. In the illustrated example, a suction pump 29 in the form of a tube pump is used, which includes a member formed with a curved surface for holding (at least a part of) a tube 28 having flexibility, and a member It is possible to have a roller capable of pressing the flexible tube toward the surface and a roller support portion that can rotate while supporting the roller. That is, by rotating the roller support portion in a predetermined direction, the roller rolls while crushing the flexible tube on the curved surface forming member. Along with this, negative pressure is generated in the sealed space formed by the cap 7 and the ink is sucked from the discharge port and drawn from the cap 27 to the tube or the suction pump, while the drawn ink further includes an appropriate member (waste ink). It is transferred toward the absorber.

  Further, the suction pump 29 can be operated not only for such suction recovery, but also for discharging ink received in the cap 27 by a preliminary ejection operation performed with the cap 27 facing the face surface. . That is, by operating the suction pump 29 when the preliminarily ejected ink held in the cap 27 reaches a predetermined amount, the ink held in the cap 27 is passed through the tube 28 to the waste ink absorber. Can be transported.

(2) Ink Next, ink that can be used in the printer having the above configuration will be described.

(2-1) Yellow ink
Preparation pigment for dispersion [C. I. Pigment Yellow 74 (product name: Hansa Brilliant Yellow 5GX (manufactured by Clariant))], 10 parts of anionic polymer P-1 [styrene / butyl acrylate / acrylic acid copolymer (copolymerization ratio (weight ratio) = 30 / 40/30), acid value 202, weight average molecular weight 6500, aqueous solution having a solid content of 10%, neutralizer: 30 parts of potassium hydroxide and 60 parts of pure water were mixed, and the materials shown below were batch-type vertical The mixture was charged into a sand mill (manufactured by IMEX), filled with 150 parts of 0.3 mm diameter zirconia beads, and dispersed for 12 hours while cooling with water. Further, this dispersion was centrifuged to remove coarse particles. As a final preparation, Pigment Dispersion 1 having a solid content of about 12.5% and a weight average particle size of 120 nm was obtained. By using the obtained pigment dispersion, an ink was prepared as follows.

Preparation of ink The following components were mixed, sufficiently stirred and dissolved / dispersed, followed by pressure filtration with a microfilter (manufactured by Fuji Film) having a pore size of 1.0 μm to prepare a yellow ink.
-Pigment dispersion 1 obtained above 40 parts-Glycerol 9 parts-Ethylene glycol 6 parts-Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 1 part-1,2-hexanediol 3 parts-Polyethylene glycol (molecular weight) 1000) 4 parts Water 37 parts.

(2-2) Magenta ink
Preparation of dispersion First, using benzyl acrylate and methacrylic acid as raw materials, an AB type block polymer having an acid value of 300 and a number average molecular weight of 2500 is prepared by a conventional method, further neutralized with an aqueous potassium hydroxide solution, and ion-exchanged water. Diluted to make a homogeneous 50 wt% polymer aqueous solution.

  100 g of the polymer solution, C.I. I. 100 g of Pigment Red 122 and 300 g of ion-exchanged water were mixed and mechanically stirred for 0.5 hour.

  The mixture was then processed using a microfluidizer by passing it through the interaction chamber 5 times under a liquid pressure of about 70 MPa.

  Furthermore, the dispersion obtained above was centrifuged (12,000 rpm, 20 minutes) to remove the non-dispersion containing coarse particles to obtain a magenta dispersion. The obtained magenta dispersion had a pigment concentration of 10% by mass and a dispersant concentration of 5% by mass.

Ink preparation The ink was prepared using the above magenta dispersion, and the following components were added to this to a predetermined concentration. After these components were sufficiently mixed and stirred, a microfilter (Fuji Film) with a pore size of 2.5 μm was used. And a pigment ink having a pigment concentration of 4% by mass and a dispersant concentration of 2% by mass was prepared.
・ Magenta dispersion 40 parts ・ Glycerin 10 parts ・ Diethylene glycol 10 parts ・ Acetylene glycol EO adduct
(Manufactured by Kawaken Fine Chemicals) 0.5 part ・ 39.5 parts of ion-exchanged water.

(2-3) Light magenta ink
Preparation of dispersion 100 g of polymer solution used in magenta ink, C.I. I. 100 g of Pigment Red 122 and 300 g of ion-exchanged water were mixed and mechanically stirred for 0.5 hour.

  The mixture was then processed using a microfluidizer by passing it through the interaction chamber 5 times under a liquid pressure of about 70 MPa.

  Furthermore, the dispersion obtained above was centrifuged (12,000 rpm, 20 minutes) to remove the non-dispersion containing coarse particles to obtain a magenta dispersion. The obtained magenta dispersion had a pigment concentration of 10% by mass and a dispersant concentration of 5% by mass.

Ink preparation The ink was prepared using the above magenta dispersion, and the following components were added to this to a predetermined concentration. After these components were sufficiently mixed and stirred, a microfilter (Fuji Film) with a pore size of 2.5 μm was used. And a pigment ink having a pigment concentration of 4% by mass and a dispersant concentration of 2% by mass was prepared.
・ Magenta dispersion 8 parts ・ Glycerin 10 parts ・ Diethylene glycol 10 parts ・ Acetylene glycol EO adduct (manufactured by Kawaken Fine Chemicals) 0.5 part ・ Ion-exchanged water 71.5 parts.

(2-4) Cyan ink
Preparation of dispersion First, using benzyl acrylate and methacrylic acid as raw materials, an AB type block polymer having an acid value of 250 and a number average molecular weight of 3000 is prepared by a conventional method, further neutralized with an aqueous potassium hydroxide solution, and ion-exchanged water. Diluted to make a homogeneous 50 wt% polymer aqueous solution.

  180 g of the above polymer solution, C.I. I. 100 g of CI Pigment Blue 15: 3 and 220 g of ion-exchanged water were mixed and mechanically stirred for 0.5 hour.

  The mixture was then processed using a microfluidizer by passing it through the interaction chamber 5 times under a liquid pressure of about 70 MPa.

  Furthermore, the dispersion obtained above was centrifuged (12,000 rpm, 20 minutes) to remove non-dispersed materials containing coarse particles to obtain a cyan dispersion. The obtained cyan dispersion had a pigment concentration of 10% by mass and a dispersant concentration of 10% by mass.

Preparation of ink Ink preparation uses the above-mentioned cyan dispersion liquid, and the following components are added to this to a predetermined concentration, and after these components are sufficiently mixed and stirred, a microfilter (Fuji Film) with a pore size of 2.5 μm is prepared. To prepare a pigment ink having a pigment concentration of 2% by mass and a dispersant concentration of 2% by mass.
-20 parts of the above-mentioned cyan dispersion liquid-10 parts of glycerin-10 parts of diethylene glycol-0.5 part of acetylene glycol EO adduct (manufactured by Kawaken Fine Chemicals)-53.5 parts of ion-exchanged water.

(2-5) Light cyan ink
Preparation of dispersion 180 g of polymer solution prepared with cyan ink, C.I. I. 100 g of CI Pigment Blue 15: 3 and 220 g of ion-exchanged water were mixed and mechanically stirred for 0.5 hour.

  The mixture was then processed using a microfluidizer by passing it through the interaction chamber 5 times under a liquid pressure of about 70 MPa.

  Furthermore, the dispersion obtained above was centrifuged (12,000 rpm, 20 minutes) to remove non-dispersed materials containing coarse particles to obtain a cyan dispersion. The obtained cyan dispersion had a pigment concentration of 10% by mass and a dispersant concentration of 10% by mass.

Preparation of ink Ink preparation uses the above-mentioned cyan dispersion liquid, and the following components are added to this to a predetermined concentration, and after these components are sufficiently mixed and stirred, a microfilter (Fuji Film) with a pore size of 2.5 μm is prepared. To prepare a pigment ink having a pigment concentration of 2% by mass and a dispersant concentration of 2% by mass.
-4 parts of the above cyan dispersion liquid-10 parts of glycerin-10 parts of diethylene glycol-0.5 part of acetylene glycol EO adduct (manufactured by Kawaken Fine Chemicals)-69.5 parts of ion-exchanged water.

(2-6) Matte black ink
After DBP oil absorption produced a surface area of at 230 m ² / g of the dispersion was well mixed carbon black 10g and p- amino -N- acid 3.41g of 70 ml / 100 g of water 72 g, this nitrate 1.62g The solution was added dropwise and stirred at 70 ° C. A few minutes later, a solution prepared by dissolving 1.07 g of sodium nitrite in 5 g of water was added, and the mixture was further stirred for 1 hour. The obtained slurry was filtered with a filter paper (trade name: Toyo Filter Paper No. 2; manufactured by Advantis Co., Ltd.), and the pigment particles collected by filtration were thoroughly washed with water and dried in an oven at 90 ° C. Was added to prepare an aqueous pigment solution having a pigment concentration of 10% by weight.

Preparation of ink The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a micro filter (manufactured by Fuji Film) having a pore size of 3 μm to prepare a black ink.
-Pigment dispersion 1 30 parts-Potassium sulfate 1 part-Trimethylolpropane 6 parts-Glycerin 6 parts-Diethylene glycol 6 parts-Acetylene glycol ethylene oxide adduct 0.2 parts (trade name: acetylenol EH; Kawaken Fine Chemicals Co., Ltd.) (Made by company)
-50.8 parts of water.

(2.7) Photo black ink
Preparation of dispersion 100 g of the polymer solution used in yellow ink, 100 g of carbon black and 300 g of ion-exchanged water were mixed and mechanically stirred for 0.5 hour. The mixture was then processed using a microfluidizer by passing it through the interaction chamber 5 times under a liquid pressure of about 70 MPa.

  Furthermore, the dispersion obtained above was centrifuged (12,000 rpm, 20 minutes) to remove non-dispersed materials containing coarse particles to obtain a black dispersion. The resulting black dispersion had a pigment concentration of 10% by mass and a dispersant concentration of 6% by mass.

Preparation of ink Ink preparation uses the above black dispersion liquid, and the following components are added to this to a predetermined concentration, and after these components are sufficiently mixed and stirred, a microfilter (Fuji Film) with a pore size of 2.5 μm is prepared. And a pigment ink having a pigment concentration of 5% by mass and a dispersant concentration of 3% by mass was prepared.
・ Black dispersion 50 parts ・ Glycerin 10 parts ・ Triethylene glycol 10 parts ・ Acetylene glycol EO adduct 0.5 parts (manufactured by Kawaken Fine Chemicals)
-25.5 parts of ion exchange water.

(3) Configuration Example of Control System FIG. 8 shows a configuration example of a printer control circuit used in this embodiment. In FIG. 8, reference numeral 101 denotes a programmable peripheral interface (hereinafter referred to as PPI), which receives a command signal (command) sent from the host computer 100 and a recording information signal including recording data and transfers it to the MPU 102. The printer status information is sent to the host computer 100 as necessary. In addition, input / output is performed with respect to a console 106 having a setting input unit for a user to make various settings for the printer and a display unit for displaying a message to the user. A signal input from a sensor group 107 including a home position sensor for detecting the home position and a capping sensor is received.

  The MPU (microprocessing unit) 102 is configured so that each unit in the printer is in accordance with a normal recording processing procedure stored in the control ROM 105 and a control program corresponding to the processing procedure described later with reference to FIG. To control. Reference numeral 103 denotes a RAM that stores received signals or is used as a work area for the MPU 102 and temporarily stores various data. A font generation ROM 104 stores pattern information such as characters and records corresponding to the code information, and outputs various pattern information corresponding to the input code information. Reference numeral 121 denotes a print buffer for storing the recording data expanded in the RAM 103 or the like, and has a capacity for recording M rows. In addition to the above control program, the control ROM 105 stores fixed data corresponding to data used in the control process described later (for example, data for determining the necessity of wiping execution according to the main part of this embodiment). Can be kept. These units are controlled by the MPU 102 via the address bus 117 and the data bus 118.

  Reference numeral 113 denotes a capping motor which serves as a drive source for raising and lowering the cap 27, moving the wiper holder 25 and operating the pump 29. Reference numerals 114, 115, and 116 denote motor drivers for driving the capping motor 113, the carriage motor 3, and the paper feed motor 5 according to the control of the MPU 102, respectively. Reference numeral 149 denotes a driver for opening and closing a valve 49 provided in an ink supply path from the ink tank.

  A sheet sensor 109 detects the presence or absence of a recording medium, that is, whether or not the recording medium is supplied to a position where recording by the recording head is possible. Reference numeral 111 denotes a driver for driving the heat generating portion 52 of the recording head 9 in accordance with the recording information signal. A power supply unit 124 supplies power to the above-described units, and includes an AC adapter and a battery as a drive power supply device.

  In the recording system including the printer and the host computer 100 that supplies the recording information signal to the printer, when the recording data is transmitted from the host computer 100 via a parallel port, an infrared port, a network, or the like, it is required at the head portion The command is added. The commands include, for example, the type of recording medium on which recording is performed (the type of plain paper, OHP sheet, glossy paper, etc., and the type of special recording medium such as transfer film, cardboard, banner paper, etc.), medium size ( A0 size, A1 size, A2 size, B0 size, B1 size, B2 size, etc.), recording quality (draft, high quality, medium quality, specific color enhancement, monochrome / color type, etc.), paper feed path (printer It is determined according to the form and type of recording medium feeding means provided (for example, ASF, manual feed, paper feed cassette 1, paper feed cassette 2, etc.) and whether or not an object is automatically identified. In addition, when a configuration for applying a treatment liquid for improving the fixability of ink on a recording medium is employed, information for determining the presence or absence of the application may be transmitted as a command.

  In accordance with these commands, the printer reads data necessary for recording from the ROM 105 described above, and performs recording based on these data. The data includes, for example, data for determining the number of printing passes when performing the above-described multi-pass printing, the ink ejection amount per printing medium unit area, the printing direction, and the like. In addition, the type of data thinning mask applied when performing multi-pass printing, the driving conditions of the recording head (for example, the shape of the driving pulse applied to the heat generating portion 52, the application time, etc.), the dot size, and the recording medium There are also conveyance conditions, carriage speed, and the like.

(4) Ink Replacement Sequence This embodiment relates to a replacement system for mat black ink and photo black ink. Specifically, in the ink supply system shown in FIGS. 5 and 6, a black ink tank is used. 39Bk is configured such that a matte black ink containing one and a photo black ink containing one can be exchanged and selectively mounted.

  FIG. 9 and FIGS. 10A to 10D show an example of a sequence and an exchange mode when the ink tank is exchanged, respectively.

  The procedure shown in FIG. 9 can be started, for example, when the user specifies the ink type or ink tank to be used, when the recording medium type is specified, or when the recording mode such as glossiness is specified. The designation may be performed using a console 106 provided in the printer main body, or may be performed using a setting screen of a printer driver operating on the host computer 100. Furthermore, it is possible to determine whether or not an ink tank that stores ink that conforms to the designation as described above is mounted, and to start in the case of a negative determination. Here, information can be presented from the ink tank side in order to determine whether an ink tank according to the designation is attached. In this case, for example, the ink tank may be provided with storage means for storing information on the type of ink stored therein. Then, the presented information can be received and the contents thereof can be determined by the MPU 102, or the contents can be determined by the host computer 100 by communicating the information via the PPI 101.

  When the procedure of FIG. 9 is started, first, in step S801, the valves 49 inserted in the ink supply paths from the ink tanks 39Bk to 39Y for all colors are closed, and the ink supply path is closed. Further, the cap 27 is raised to perform capping. At this time, the black ink tank to be replaced is indicated by reference numeral 39Bk in FIG. 11A (for matte black ink or for photo black ink), and the black ink tank to be mounted instead is shown in FIG. In (a), it is assumed that it is indicated by reference numeral 39Bk ′ (for photo black ink or matte black ink).

  In step S802, the user is requested to remove the black ink tank Bk to be replaced. This request may be made through the display unit of the console 106 provided in the printer main body, or may be made through a setting screen of a printer driver operating on the host computer 100.

  Then, the pump 29 is driven for a predetermined time (for example, 30 seconds) in the state of FIG. 10B in which the ink tank Bk is removed (and the ink tank Bk ′ is not attached) (step S803). As a result, the suction process is performed with the valve 49 closed, so that all the discharge sections or the ink supply path are decompressed.

  In step S804, the valve 49 is opened only in the black ink supply path. As a result of this operation, the black ink remaining in the supply path flows into the pressure-reduced black discharge section 11, while air flows into the supply path because the tank is removed. Then, by repeating the suction operation in step S803 and the valve opening operation in step S804 a predetermined number of times (for example, 7 times), air enters the discharge section 11 and the ink supply system is almost filled with air. This state is shown in FIG.

  Subsequently, in step S807, a request is made to install an ink tank 39Bk 'different from the ink tank 39Bk so far. From this state, the same process as in steps S803 and S804 is repeated seven times in step S808, so that new ink is filled in the ink supply system including the ejection unit 11. This state is shown in FIG.

  After that, all the valves 49 are opened in step S809, the pump 29 is driven for a predetermined time (for example, 5 seconds) in step S810, the suction operation is executed, the wiping process is executed in step S811, and finally the step In step S812, preliminary ejection is executed, and the ink tank replacement sequence ends.

  In this embodiment, the ink exchange system is replaced by replacing the ink tank. However, two ink tanks are provided in advance and the ink supply path is switched to support the ink replacement system. It may be.

(5) Configuration of Face Surface In the present embodiment, an ink exchange system between matte black ink and photo black ink is used. Any of these inks (described in the above (2.6) and (2.7)) can be stably ejected to a highly water-repellent face surface. As the ink discharge section 11, an ink discharge section 11 having a highly water-repellent face surface was used. However, when the two inks are replaced and used as described above, the water-repellent performance of the face surface is remarkably deteriorated, and the ink ejection performance causes severe kinking for either ink. It was. In the following, this cause is clarified and a desirable face performance selection is presented.

  First, using the ink set described above, a wiping durability test of the recording head was performed for each ink.

  FIG. 11 shows an embodiment of such a wiping durability test. First, in step S901, the recording head 9 is moved onto the cap 27 to perform preliminary ejection. This causes ink to adhere to the face surface and wet the face surface. In step 902, wiping is executed. Then, by repeating these processes a predetermined number of times (for example, 2000 times) (step S903), it becomes possible to wet the face surface in an accelerated manner corresponding to actual use. When the face surface gets wet by carrying out this wiping durability test, the discharge accuracy decreases due to this.

  This durability test was conducted on the above seven types of ink including two types of black ink. In addition, the durability test was performed on both the water repellent surface and the non-water repellent surface of the head face at this time.

  Table 1 below shows the resulting wetness of the face surface and the state of deterioration (cracking) of the discharge accuracy.

Evaluation criteria for wetting Evaluation criteria for wetting ◎: No wetting ◎: No wetting ○: Wetting slightly ○: Wetting slightly △: Wetting uniformly ×: Wetting intensely ×: Wetting intensely-: Undecidable

  As is clear from this table, there was no problem with respect to both the water repellent surface and the non-water repellent surface except for the yellow ink. In the yellow ink, only the ink having a low surface tension is used in this embodiment, and it was confirmed that the ink overflows with respect to the non-water-repellent surface. For other inks, water repellency was maintained when the water-repellent surface was used, and for the non-water-repellent surface, the face surface could be applied uniformly, so wetting of the face surface occurred but no kinking occurred. .

  In particular, when the matte black ink and the photo black ink were used exclusively, when the water repellent surface was used, slight wetting and twisting were confirmed, but this was not at a level causing problems in practical use.

However, the present embodiment relates to an ink exchange system between matte black ink and photo black ink, and even if the exchange is performed according to the sequence shown in FIG. 9, that is, after the ink tank 39Bk is removed, the ink tank 39Bk. Even if the ink supply system including the discharge unit 11 is almost filled with air before mounting ', the ink supplied from the ink tank 39Bk cannot be completely removed from the ink supply system including the discharge unit 11 and replaced. Later, the ink may be newly mixed with ink supplied from the ink tank 39Bk ′. Therefore, even for such mixed ink, the face surface of the discharge section 11 should be able to maintain discharge accuracy. For this purpose, the present inventors created three types of ink with different mixing ratios for the matte black ink and the photo black ink applied to the ink exchange system, and the face surface of the ejection unit for the three types of ink. The durability test as described above was performed on both the water repellent surface and the non-water repellent surface. Table 2 below shows the results.

Evaluation criteria for wetting Evaluation criteria for wetting ◎: No wetting ◎: No wetting ○: Wetting slightly ○: Weighing slightly △: Wetting uniformly △: Wetting ×: Wetting intensely and unevenly ×: Weighing intensely

  As is apparent from this table, it was confirmed that even when two types of inks that do not substantially warp by themselves are mixed, the water-repellent surface is wetted by mixing them, and severe warping occurs. The mechanism of the wetting of the face surface by this mixing is not yet clear, but it is thought that the ink became unstable due to the mixing of both inks and violently aggregated on the face surface.

  For this reason, the non-water-repellent surface is adopted as the face surface of the ejection unit that uses the mat black ink and the photo black ink for performing the ink replacement sequence. The reason for this is that, even after the ink replacement sequence as described above, some ink before replacement remains in the ink supply system, and the wettability (affinity) of the mixed ink with respect to the face surface becomes a problem.

  From the above, in the case of the present embodiment, either the water-repellent or non-water-repellent face surface may be selected for each of the light cyan, light magenta, magenta, and cyan ink ejection portions that do not perform ink replacement. It was concluded that the water-repellent surface is desirable, and that the non-water-repellent surface is preferable for the discharge part used by replacing the matte black ink and the photo black ink.

  FIG. 12 is a schematic diagram showing a face surface configuration for each ejection portion of the recording head 9 of the present embodiment adopted based on this. Here, the discharge portion 11 for black ink has a non-water-repellent surface 1001 (the non-water-repellent surface may be formed by applying the material constituting the discharge portion as it is, or may be positively subjected to a hydrophilic treatment. ), And the other face surfaces of the discharge portions 12 to 16 are water-repellent surfaces 1002. In particular, with respect to the yellow ink, the water repellent surface is positively employed because the ink overflows on the non-water repellent surface as described above. Any remaining color may be used, but the water-repellent surface is known to have less ink color mixing during cleaning, and therefore the water-repellent surface was adopted.

(6) Others In the present invention, in the system in which the first and second inks are exchanged and used, the ejection characteristics for all of the first ink, the second ink, and the mixed ink obtained by mixing them. The main feature is to have a face surface configuration that does not damage the surface. In the above-described embodiment, in the ink exchange system between the photo black ink and the matte black ink, when the wettability (affinity) regarding the face surface of the mixed ink becomes a problem and the ejection accuracy deteriorates, the ink exchange system The non-water-repellent surface is used on the face surface that uses, so that the discharge accuracy is maintained.

  However, as a matter of course, it is possible to appropriately select a face surface configuration that does not impair the ejection characteristics with respect to other conditions and ink types.

  For example, as other conditions, for at least one ink of the first ink, the second ink, and a mixed ink in which these are mixed, the affinity for the water-repellent surface when solvent evaporation occurs is relatively The case is expensive. For example, if ink adheres to the face surface, solvent evaporation may proceed. Further, when performing the recovery process using the recovery system unit shown in FIG. 7, particularly when wiping is performed, ink adheres to the wiper blade 21, and the ink whose solvent has progressed advances to the face surface by the next wiping. May be retransferred. Therefore, there is a possibility that ink before replacement and ink after replacement may be mixed. Therefore, in such a case, the face surface can be configured so as not to exhibit water repellency under the condition that the affinity for the water repellent surface is relatively high.

  Further, the present invention is not limited to the above-described embodiment, and the tone number and type such as the color and density of the ink to be used can be determined as appropriate. A face surface configuration can be adopted.

  For example, when the surface tension is relatively low with respect to at least one of the first ink, the second ink, and the mixed ink obtained by mixing them, the face surface is configured to exhibit water repellency. You can also. This is because if at least one of these inks has a low surface tension, a phenomenon of ink overflowing to the non-water-repellent surface occurs.

  Further, there are various ink ejection methods applied to the printer, and as described above, an electrothermal conversion element that generates thermal energy that causes film boiling in ink when energized is used. Alternatively, a device provided with an electromechanical energy conversion element such as a piezo element may be used.

  In addition, in the above example, the case where the present invention is applied to a so-called serial type printer has been described. However, the present invention relates to a so-called full-line type ink jet recording head in which nozzles are arranged over a range corresponding to the entire width of the recording medium. This is also effective for the printer to be used.

1 is a schematic perspective view showing an appearance of an ink jet recording apparatus (printer) according to an embodiment of the present invention. FIG. 2 is a schematic perspective view showing a recording head mounted on a carriage unit of the printer of FIG. 1 from a direction in which ink is ejected. FIG. 3 is a schematic perspective view of an ejection unit provided in the recording head of FIG. 2. FIG. 3 is a schematic longitudinal sectional view of the recording head of FIG. 2. FIG. 3 is a schematic perspective view illustrating a configuration example of an ink supply system to the recording head of FIG. 2. It is explanatory drawing for demonstrating the internal structure of the ink supply system corresponding to the ink of 1 color. FIG. 3 is a schematic perspective view illustrating a configuration example of a recovery unit for the recording head of FIG. 2. FIG. 2 is a block diagram illustrating a configuration example of a printer control circuit used in an embodiment of the present invention. It is a flowchart which shows the example of the ink replacement sequence by embodiment of this invention. (A)-(d) is explanatory drawing for demonstrating the replacement | exchange aspect of an ink tank. It is a flowchart for demonstrating the aspect of a wiping durability test. FIG. 3 is a schematic diagram illustrating a face surface configuration with respect to each ejection unit of the recording head of the embodiment. FIG. 3 is a schematic diagram illustrating a configuration of a general recording head.

Explanation of symbols

2 Carriage unit 3 Carriage motor 5 Paper feed motor 9 Recording head 11-16 Ejection part 21, 22 Wiper blade 23 Ink introduction part 25 Wiper holder 27 Cap 29 Suction pump 39Bk, 39Bk ', 39Lc, 39C, 39Lm, 39M, 39Y Ink tank 45 Supply tube 49 Valve 52 Heating section 55 Nozzle 100 Host computer 102 MPU
103 RAM
105 ROM
121 Print buffer 1001 Non-water-repellent surface 1002 Water-repellent surface

Claims (7)

In an ink jet recording head having an ejection part capable of ejecting by exchanging the first ink and the second ink having different characteristics,
The portion of the discharge portion where the ink discharge port is provided corresponds to all of the first ink, the second ink, and the mixed ink obtained by mixing the first ink and the second ink. And an ink jet recording head configured to maintain ejection characteristics.   When at least one of the first ink, the second ink, and the mixed ink obtained by mixing the first ink and the second ink has a relatively high affinity for the water repellent surface The ink jet recording head according to claim 1, wherein the portion is configured so as not to exhibit water repellency.   With respect to at least one ink of the first ink, the second ink, and the mixed ink obtained by mixing the first ink and the second ink, the water repellent surface when the solvent has evaporated is generated. 2. The ink jet recording head according to claim 1, wherein when the affinity is relatively high, the portion is configured not to exhibit water repellency.   The ink jet recording head according to claim 2, wherein the portion is configured so as not to exhibit the water repellency by performing a hydrophilic treatment.   When at least one of the first ink, the second ink, and the mixed ink obtained by mixing the first ink and the second ink has a relatively low surface tension, The ink jet recording head according to claim 1, wherein the portion is configured to exhibit water repellency.   An inkjet recording apparatus that performs recording using the inkjet recording head according to claim 1, wherein the first ink and the second ink are switched with respect to the ejection unit. An ink jet recording apparatus comprising means for selectively supplying. The ink jet recording apparatus according to claim 6, further comprising means for removing ink to be replaced from an ink supply system including the ejection unit at the time of the switching.

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