JP4854550B2 - Cap member for ink jet recording apparatus and ink jet recording apparatus - Google Patents

Description

  The present invention relates to a cap member for an ink jet recording apparatus that covers a nozzle surface in a state where a contact portion is in contact with a nozzle surface of an ink jet recording head that discharges liquid.

  An ink jet recording apparatus includes an ink jet recording head (hereinafter referred to as a recording head) that discharges recording ink that is liquid, and ejects ink from a nozzle surface to a recording medium through fine nozzles in the recording head. It is necessary to prevent ink from adhering to or remaining on the nozzle surface so that the discharged ink lands on the recording medium stably and accurately. For this reason, the nozzle surface is generally water-repellent. Further, the ink jet recording apparatus needs to prevent the ink in the nozzles from being dried during the non-recording operation, and generally includes a cap member that covers the nozzle surface during the non-recording operation.

  When covering the nozzle surface, the cap member seals the space formed by the recess and the nozzle surface by bringing the contact portion around the recess into contact with the nozzle surface, thereby drying the nozzle surface. To prevent.

  In order to seal the space formed by the concave portion of the cap member and the nozzle surface, the cap member needs to be formed of an elastic material so as not to allow gas to pass therethrough and to easily adhere to the nozzle surface. . For this reason, the conventional cap member was formed with synthetic rubbers, such as chlorinated butyl rubber with low gas permeability (for example, refer to patent documents 1).

  In addition, when covering the nozzle surface with the cap member, in order to further prevent the nozzle surface from drying, a predetermined amount of ink is ejected in advance into the concave portion of the cap member, and the concave portion of the cap member is maintained at a substantially saturated vapor pressure. The For this reason, the cap member is always in contact with the ink.

By the way, in order to improve the color reproducibility of image recording and to improve fading resistance, diversification of ink materials is progressing. In addition, as ink jet recording apparatuses are increasingly used for production apparatuses, ink solvents that can dissolve synthetic rubber as described above may be used. For this reason, the cap member needs to be formed of a material having chemical resistance.
Japanese Patent Laid-Open No. 5-131539

  However, materials with higher chemical resistance tend to have higher water repellency. Further, when ink is ejected into the recess of the cap member, the ink may adhere to the contact portion of the cap member. The ink adhering to the contact portion also adheres to the nozzle surface when the cap member covers the nozzle surface.

  Since the conventional cap member has high water repellency, the difference in height between the water repellency of the cap member and the water repellency of the nozzle surface is small, and ink may remain on the nozzle surface after the cap member is separated. If ink remains on the nozzle surface, the ink landing accuracy decreases.

  An object of the present invention is to provide a cap member for an ink jet recording apparatus that suppresses a decrease in the landing accuracy of liquid ejected from a recording head by suppressing the liquid from remaining on the nozzle surface of the recording head. is there.

  The cap member of the ink jet recording apparatus of the present invention includes a recess and a contact portion around the recess, and ink jet recording that covers the nozzle surface in a state where the contact portion contacts the nozzle surface of the ink jet recording head that discharges the liquid. It is a cap member of the apparatus, and the contact portion is formed of a rubber member having chemical resistance and subjected to a hydrophilic treatment.

  In this configuration, since the abutting portion that abuts the nozzle surface is hydrophilized, the liquid adheres to the cap member and does not remain on the nozzle surface when the cap member is separated from the state of covering the nozzle surface.

  The rubber member may be a rubber member crosslinked with a peroxide. According to this configuration, since the contact portion has chemical resistance, even when ink adheres to the contact portion, the contact portion is inhibited from being eluted into the ink.

  The rubber member may be fluororubber. According to this configuration, the chemical resistance of the contact portion is further increased.

  At least the contact portion may be coated with a hydrophilic metal film. According to this configuration, the liquid adheres to the contact portion and does not remain on the nozzle surface.

  All portions to which the liquid adheres may be covered with a metal film. According to this configuration, since the contact portion has hydrophilicity, the liquid adheres to the contact portion and does not remain on the nozzle surface. Moreover, since all the parts to which the liquid adheres are covered with a metal film, a material with low chemical resistance can be used for the base of the metal film by covering with a metal film having high chemical resistance.

  According to this invention, since the contact portion of the cap member is subjected to a hydrophilic treatment, it is possible to prevent the liquid from remaining on the nozzle surface after the cap member is separated from the state where the cap surface is covered. . Therefore, it is possible to suppress a decrease in the landing accuracy of the liquid ejected from the recording head.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a front view showing a schematic configuration of an ink jet recording apparatus including a cap member 10 according to an embodiment of the present invention.

  The ink jet recording apparatus 1 includes a gantry 2, a head unit 3, a suction disk 4, a head lower limit sensor 5, and a cap member 10.

  The gantry 2 is movable in the direction of arrow X in FIG. The head unit 3 is supported by the gantry 2. The head unit 3 has an ink jet recording head 6 mounted at the bottom. The recording head 6 has a nozzle surface 61 on the lower surface. In the recording head 6, nozzles to which the ink which is the liquid of the present invention is supplied are formed, and one end of the nozzle is opened in the nozzle surface 61. The ink is ejected from the nozzle surface 61 through the nozzle.

  The nozzle surface 61 is made of polyimide, and the entire surface of the nozzle surface 61 is subjected to water repellent treatment. Generally, when the contact angle between the ink adhering to the nozzle surface 61 and the nozzle surface 61 is 80 degrees or more, the ink adhering to the nozzle surface 61 is wiped when the nozzle surface 61 is wiped using a rubber blade or the like. Removed without wiping. In this embodiment, the contact angle between the nozzle surface 61 and the ink is set to 100 degrees by subjecting the nozzle surface 61 to water repellent treatment.

  The suction disk 4 is arranged so that the upper surface is located below the nozzle surface 61 of the recording head 6. A recording medium is disposed on the upper surface of the suction disk 4. In this embodiment, paper P is disposed as a recording medium. When the ink jet recording apparatus 1 is used as a production apparatus, a liquid crystal filter substrate, for example, is disposed as a recording medium.

  The cap member 10 is disposed at a position facing the nozzle surface 61 in a state where the head unit 3 is at a predetermined standby position that is out of the recording position on the suction disk 4. The cap member 10 is movable up and down by a motor 8.

  The cap member 10 rises and comes into contact with the nozzle surface 61 when capping to cover the nozzle surface 61. The cap member 10 is lowered and separated from the nozzle surface 61 during the recording operation in which the recording head 6 ejects ink onto the paper P. During the recording operation, the gantry 2 moves above the suction plate 4 and performs a predetermined recording operation by ejecting ink from the nozzle surface 61 of the recording head 6.

  The head lower limit sensor 5 detects the height of the nozzle surface 61 of the recording head 6 in the middle of the path along which the gantry 2 moves from the standby position onto the suction disk 4. When the head lower limit sensor 5 detects that the nozzle surface 61 is less than or equal to a predetermined height, the ink jet recording apparatus 1 immediately stops because the nozzle surface 61 may abut or collide with the paper P. In this embodiment, a displacement sensor using laser light is used as the head lower limit sensor 5. Specifically, in this embodiment, the height of the recording head 6 is set so that the distance in the height direction between the nozzle surface 61 and the paper P is 0.5 mm. It is set to detect whether or not the distance in the height direction between the surface 61 and the paper P is 0.3 mm or less.

  FIG. 2 is a front view showing the configuration of the cap member 10.

  The cap member 10 includes a cap main body 11, an ink absorber 12, and an ink discharge pipe 13.

  The cap body 11 is formed in a cup shape, and includes a recess 111 and a contact portion 112 that is a portion around the recess 111 and a portion that contacts the nozzle surface 61. The cap body 11 is held by the cap holding member 9 so that the recess 111 faces the nozzle surface 61. The cap holding member 9 is moved up and down by the motor 8. The ink absorber 12 is disposed in the recess 111 of the cap body 11. The ink discharge pipe 13 discharges the ink stored in the ink absorber 12 to the outside of the cap body 11.

  The cap member 10 is raised during the non-recording operation of the recording head 6 and during the recovery operation of performing the idle ejection or the preliminary ejection in order to eliminate clogging of the nozzles, so that the contact portion 112 contacts the nozzle surface 61. Capping the nozzle surface 61 in contact.

  When the cap member 10 caps the nozzle surface 61, the cap body 11 and the nozzle surface 61 are formed by bringing the contact portion 112 of the cap body 11 into close contact with the nozzle surface 61 in order to prevent ink in the nozzle from drying. The space in the recessed portion 111 to be sealed is sealed. At the time of capping, a predetermined amount of ink is ejected in advance into the recess 112, and the interior of the recess 112 is maintained at a substantially saturated vapor pressure. The contact portion 112 is in close contact with the nozzle surface 61 by elastic deformation.

  The cap body 11 is formed of a rubber member having chemical resistance. In this embodiment, the cap body 11 is formed of Kalrez (manufactured by DuPont) made of a fluororesin perfluoroelastomer. Kalrez is fully fluorinated and has excellent heat and chemical resistance. The contact portion 112 of the cap body 11 is subjected to a hydrophilic treatment. In this embodiment, a metal film by Ni (nickel) plating is formed on the contact portion 112. The contact angle of the ink at the contact portion 112 is 80 degrees in the state of Kalrez before the metal film is formed, but is 30 degrees when the metal film is formed. .

  FIG. 3 is a diagram showing an experimental result of examining the degree of ink remaining on the nozzle surface 61 due to the difference in water repellency of the contact portion 112.

  In this experiment, the setting is changed so that the head lower limit sensor 5 detects that the distance in the height direction between the nozzle surface 61 and the paper P is 0.45 mm or less. Further, after the nozzle surface 61 is wiped by the rubber blade, the nozzle surface 61 is once capped by the cap member 10 and the cap member 10 is moved away from the nozzle surface 61, and then the head unit 3 is moved to the recording position. This process was repeated 500 times to confirm whether there was ink remaining on the nozzle surface 61.

  In addition, under the same conditions, Example 2 in which the above-described metal film was formed on all the portions of the cap body 11 where the ink can be adhered, and the metal film was not formed on the abutting portion 112 and the Kalrez remained as it was. Whether or not there is ink remaining on the nozzle surface 61 was also confirmed for the comparative example of the state. Furthermore, the height fluctuation of the nozzle surface 61 before and after each experiment was confirmed by a micro gauge, and it was confirmed that there was no difference in the height of the nozzle surface 61 before and after the experiment.

  The number of detections shown in FIG. 3 is the number of times that the head lower limit sensor 5 detects residual ink having a height of 0.05 mm or more on the nozzle surface 61. As shown in FIG. 3, in Example 1 in which the metal film was formed only on the contact portion 112, the ink remaining on the nozzle surface 61 was not detected, and good results were obtained. Also, in the actual recording operation, the occurrence of non-ejection was reduced and the ink landing accuracy was maintained high. Similarly good results were obtained for Example 2. On the other hand, in the comparative example in which the contact portion is not subjected to the hydrophilic treatment, the ink remaining on the nozzle surface 61 may be detected.

  From this experimental result, in the state where the ink Q is attached to the contact portion 112 of the cap member 10 as shown in FIG. 4A, the cap member 10 moves the nozzle surface 61 as shown in FIG. Even when capping, since the contact portion 112 is subjected to a hydrophilic treatment, the ink Q adheres to the contact portion 112 and the ink Q is prevented from remaining on the nozzle surface 61 as shown in FIG. I can confirm that I can do it.

  In Example 1, Kalrez was used as the material of the cap body 11, but a rubber member that has been crosslinked with a peroxide can also be used. According to this, since the cap main body 11 has chemical resistance, even when the ink adheres to the cap main body 11, the cap main body 11 is suppressed from being eluted into the ink. If fluororubber is used as the material of the cap body 11, the chemical resistance of the cap body 11 becomes higher among the rubber members that are crosslinked by peroxide.

  In the configuration of Example 1, when Viton (manufactured by DuPont) made of fluororubber is used as the material of the cap body 11, the chemical resistance to ink is slightly inferior to that of Kalrez. The contact angle was 75 degrees, and there was almost no difference from Example 1. This is presumably because there is no difference in the hydrophilicity of the contact portion 112 because a metal film is formed on the contact portion 112. For this reason, if there is chemical resistance to the ink, PTFE (polytetrafluoroethylene) or a silicon-based material can be used as the material of the cap body 11.

  Also in Example 2, the ink remaining on the nozzle surface 61 was not detected, and good results were obtained. This is considered to be because the hydrophilicity of the contact portion 112 is the same as that of the first embodiment.

  As in the second embodiment, the above-described metal film is formed on all the portions of the cap body 11 where the ink can adhere, so that even a material having low chemical resistance can be used as the material of the cap body 11. . Considering the adhesion with the nozzle surface 61 at the time of capping, it is preferable to use a material having a low hardness in the rubber member. Therefore, a material having a rubber hardness lower than that of a fluorine-based material can be selected.

  However, in the ink jet recording apparatus 1, the cap body 11 repeatedly abuts on the nozzle surface 61 and elastically deforms during capping, so that the rubber member is exposed due to wear or peeling of the metal film after long-term use. In consideration of the above, it is preferable to use a peroxide-crosslinked rubber member as the material of the cap body 11 in an apparatus that requires high reliability such as a production apparatus or an apparatus that is difficult to maintain over a long period of time. Long-term reliability is ensured by using a fluorine-type material with excellent chemical resistance.

  Ethers and amines, which are difficult to use with conventional fluororubbers having carbon-hydrogen bonds in part, especially when a fully fluorinated fluororubber such as perfluoroelastomer is used as the material of the cap body 11 It is highly versatile because it exhibits stability to most chemicals such as ketones, oxidants, organic solvents, fuels, acids, alkalis, etc. and has the elasticity of rubber.

  As the material for the metal film, other materials can be selected as long as they have hydrophilicity and chemical resistance instead of Ni (nickel). However, when the thickness of the metal film is less than 5 μm, the durability is inferior, and when it exceeds 20 μm, elastic deformation during capping becomes difficult, so that it is preferably 5 μm or more and 20 μm or less.

  As the hydrophilization treatment of the contact portion 112 of the cap body 11, instead of the configuration in which a metal film is formed, the contact portion 112 may be immersed in the ink for a predetermined time after the plasma treatment. According to this configuration, the ink contact angle at the contact portion 112 can be set to about 40 degrees, and in the same experiment as the above-described experiment using the head lower limit sensor 5, it is confirmed that the ink remains on the nozzle surface 61. There wasn't.

  As another means for hydrophilizing the contact portion 112, the surface of the contact portion 112 can be roughened by sandblasting. In this case, it is difficult to measure the contact angle, but the contact angle is substantially close to 0 degree, and no ink remains on the nozzle surface 61. In this case, as the sandblasting material to be used, one having a smaller particle diameter is preferable, and for example, one having # 2000 to 4000 (average diameter 2.6 μm to 7.3 μm) is used. In addition, since the nozzle surface 61 is damaged when the polishing material remains in the contact portion 112, it is preferable to use calcium carbonate or baking soda as the polishing material for sandblasting.

  The means for hydrophilizing the contact portion 112 can be selected depending on the material of the cap body 11, the interval at which the inkjet recording apparatus 1 is subjected to maintenance, the required high ink landing accuracy, and the like.

  Finally, the description of the above-described embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

1 is a front view illustrating a schematic configuration of an ink jet recording apparatus including a cap member according to an embodiment of the present invention. It is a front view which shows the structure of a cap member. It is a figure which shows the experimental result investigated about the residual degree of the ink to the nozzle surface by the difference in the water repellency of a contact part. (A) shows a state before the cap member covers the nozzle surface, (B) shows a state where the cap member covers the nozzle surface, and (C) shows a state after the cap member is separated from the nozzle surface. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Gantry 3 Head unit 4 Suction board 5 Head lower limit sensor 6 Inkjet recording head 7, 8 Motor 10 Cap member 11 Cap main body 12 Ink absorber 13 Ink discharge pipe 61 Nozzle surface 111 Concave portion 112 Contact portion P Paper ( recoding media)

Claims (7)

A cap member for an ink jet recording apparatus, comprising a recess and a contact portion around the recess, and covering the nozzle surface in a state where the contact portion is in contact with a nozzle surface of an ink jet recording head that discharges liquid. ,
The abutting portion is a cap member of an ink jet recording apparatus that is formed of a rubber member having chemical resistance and is subjected to a hydrophilic treatment.   The cap member for an ink jet recording apparatus according to claim 1, wherein the rubber member is a rubber member crosslinked with a peroxide.   The cap member of the ink jet recording apparatus according to claim 2, wherein the rubber member is fluororubber.   The cap member of the ink jet recording apparatus according to claim 1, wherein at least the contact portion is covered with a hydrophilic metal film.   The cap member of the ink jet recording apparatus according to claim 4, wherein all portions to which the liquid adheres are covered with the metal film. The contact portion is formed in a cup shape having the recess and the contact portion,
The cap member of the ink jet recording apparatus according to claim 1, wherein the contact portion is in close contact with the nozzle surface by being elastically deformed when contacting the nozzle surface. A cap member according to any one of claims 1 to 6;
An ink jet recording head for discharging liquid;
An ink jet recording apparatus comprising: a motor that moves the cap member in a direction in which the cap member is separated from or contacting the nozzle surface of the ink jet recording head.

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