WO2006075477A1 - Ink jet head and image forming method - Google Patents

Ink jet head and image forming method Download PDF

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Publication number
WO2006075477A1
WO2006075477A1 PCT/JP2005/023118 JP2005023118W WO2006075477A1 WO 2006075477 A1 WO2006075477 A1 WO 2006075477A1 JP 2005023118 W JP2005023118 W JP 2005023118W WO 2006075477 A1 WO2006075477 A1 WO 2006075477A1
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Prior art keywords
ink
image forming
forming method
chamber
jet head
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PCT/JP2005/023118
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French (fr)
Japanese (ja)
Inventor
Ai Kondo
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Konica Minolta Medical & Graphic, Inc.
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Publication of WO2006075477A1 publication Critical patent/WO2006075477A1/en

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01Ink jet
    • B41J2/135Nozzles
    • B41J2/14Structure thereof only for on-demand ink jet heads
    • B41J2/14201Structure of print heads with piezoelectric elements
    • B41J2/14209Structure of print heads with piezoelectric elements of finger type, chamber walls consisting integrally of piezoelectric material

Definitions

  • the present invention relates to an inkjet head and an image forming method using the same.
  • the ink jet head is imparted with energy to the ink supplied to the ink flow path by a piezoelectric member or the like, as is well known, and the tip of the ink flow path
  • a piezoelectric member or the like As is well known, and the tip of the ink flow path
  • various types such as those that eject ink droplets (drop-on-demand type).
  • FIG. 1 is a perspective view showing a structure of a conventional shear mode type ink jet head
  • FIG. 2 is a side sectional view at that time.
  • 1 is a piezoelectric ceramic substrate
  • 2 is a nose plate
  • 3 is a nose plate
  • 4 is an ink channel (groove)
  • 5 is a side wall
  • 6 is a cover plate
  • 7 is a common ink chamber
  • 8 is ink. Supply port.
  • the piezoelectric ceramic substrate 1 is cut by a diamond blade or the like, and a plurality of ink flow paths (grooves) 4 are all formed in parallel with the same shape. 5 is divided in the direction of the arrow.
  • a metal electrode 9 is formed on the inner surface of the ink flow path (groove) 4 by sputtering or the like.
  • the cover plate 6 is formed of a ceramic material or a resin material, and an ink supply port 8 and a common ink chamber 7 are formed by grinding or cutting. Then, the surface of the piezoelectric ceramic substrate 1 where the ink flow path (groove) 4 is processed and the surface of the cover plate 6 where the common ink chamber 7 is processed are bonded with an epoxy adhesive or the like. A flow path is formed.
  • Ink supply source ink tank force not shown in the supply ink chamber 7 Ink flows through the ink supply port 8, and each ink flow path 4 is filled with ink.
  • a drive voltage is applied to the metal electrode, and the side wall 5 is suddenly deformed. This deformation reduces the volume of the ink flow path (groove) 4.
  • the ink pressure rapidly increases, a pressure wave is generated, and ink droplets are ejected from the nozzle 3 communicating with the ink flow path (groove) 4.
  • the side wall 5 gradually returns to the position before the deformation, so that the ink pressure in the ink flow path (groove) gradually decreases. Then, ink is supplied from the ink supply source to the ink flow path (groove) 4 through the ink supply port 8 and the common ink chamber 7.
  • the inkjet head configured as described above uses a piezoelectric element, which is a functional material, as a flow path substrate, and the flow path substrate itself serves as a piezoelectric generating means, so that the flow path and the nozzle density are increased. Let's make it possible.
  • Some inkjet heads are provided with openings at both ends of the manifold for the purpose of improving the efficiency of cleaning in the head during production (for example, see Patent Document 7). These are the inlet and outlet, which are different from the purpose of stably ejecting ink from the nozzle.
  • the actinic ray curable inkjet ink is used to make a transparent recording having no ink absorbability.
  • white ink When printing on recording media, it is desirable to use white ink to ensure visibility, and the power to use inorganic white pigments such as titanium oxide as white ink pigments. It has the characteristic of being easily settled.
  • inorganic white pigments such as titanium oxide as white ink pigments. It has the characteristic of being easily settled.
  • supplying such ink to the ink head if there is a dead flow area in the ink chamber, a liquid pool will be generated, and the precipitate will easily accumulate. Uniformity cannot be maintained.
  • Patent Document 1 JP-A-6-234216
  • Patent Document 2 W ⁇ 99 / 29787
  • Patent Document 3 Japanese Patent Publication No. 2000-504778
  • Patent Document 4 Japanese Patent Laid-Open No. 2001-220526
  • Patent Document 5 Japanese Unexamined Patent Application Publication No. 2002-188025
  • Patent Document 6 Japanese Unexamined Patent Publication No. 2003-55449
  • Patent Document 7 Japanese Unexamined Patent Application Publication No. 2004-90469
  • Patent Document 8 Japanese Patent No. 3507169
  • the present invention has been made in view of the above problems, and an object of the present invention is to supply high-viscosity ink by supplying ink so that a liquid pool does not occur in a common ink chamber in an inkjet head.
  • Ink jet head that can prevent ink discharge failure and contamination during ink replacement even when ink with high sedimentation property is used, ink supply is quick, and high-speed recording is possible, and image forming method using the same Is to provide.
  • one aspect of the present invention includes a plurality of nozzles that eject ink, and a plurality of ink streams that communicate with the plurality of nozzles and that are provided as grooves in the piezoelectric ceramic.
  • An inkjet head having a path and a common ink chamber for distributing and filling ink in the ink flow path.
  • An ink jet head and an image forming method using the ink jet head are provided with at least two ink supply ports for supplying ink to the common ink chamber.
  • FIG. 1 is a perspective view showing the structure of a conventional shear mode type ink jet head.
  • FIG. 2 is a side sectional view showing the structure of the shear mode type ink jet head of FIG.
  • FIG. 3 is a cross-sectional view showing a conventional shear-type inkjet head.
  • FIG. 4 is an explanatory diagram showing the flow of ink in the common ink chamber when the ink supply port 8 is only on one side.
  • FIG. 5 is a cross-sectional view showing an example of an embodiment of an ink jet head of the present invention in which ink supply ports are provided at two locations on both side surfaces of a common ink chamber.
  • FIG. 6 is a cross-sectional view showing an example of the form of the ink jet head of the present invention in which two ink supply ports are provided on the surface of the ink chamber facing the nozzle surface.
  • FIG. 7 is a cross-sectional view showing an example of the form of the ink jet head of the present invention in which two ink supply ports are provided on the upper surface of the cover plate 6.
  • an image forming method for forming an image on a recording medium by using an ink jet head having an ink chamber an ink supply port for supplying ink from an ink supply source to the common ink chamber is provided.
  • An image forming method comprising: forming an image on a recording medium by ejecting an ink jet head provided at a plurality of positions, and ejecting an ink having a viscosity of 7 to 10 OmPa's at 25 ° C.
  • an image forming method for forming an image on a recording medium by using an ink jet head having an ink chamber an ink supply port for supplying ink from an ink supply source to the common ink chamber is provided.
  • An image forming method comprising: forming an image on a recording medium by ejecting ink containing a pigment having a specific gravity of 2.0 or more using an ink jet head provided at more than one location.
  • An inkjet head of the present invention includes a plurality of nozzles that eject ink, a plurality of ink channels that communicate with the plurality of nozzles, and that are provided as grooves in a piezoelectric ceramic, and ink that flows into the ink channels.
  • the ink supply source for the common ink chamber should be provided with two or more ink supply ports for supplying ink.
  • the ink supply port is characterized by being provided at two or more locations, and more preferably at 2 to 4 locations. If there are more than four locations, there is a concern that the configuration of the head is complex and difficult to handle. Further, the installation location is preferably set so that there is no dead flow area, and for example, it is more preferable to install near the corner of the head where the dead flow area is easily formed.
  • FIG. 3 is a diagram showing a conventional shear-type ink jet head, and is common when the ink supply port 8 is at one central position, and FIG. 4 is common when the ink supply port 8 is only on one side.
  • FIG. 5 is an explanatory diagram showing the flow of ink in the ink chamber.
  • the ink flows into the ink flow path 4 while spreading radially.
  • a dead flow area with almost no flow velocity is created in the corner (A) of the opposite surface to the ink flow path 4 of the common ink chamber, and a liquid pool is generated. Air bubbles, impurities, and sediment accumulate here, and if they are used for a long time, they gather together and flow into the ink flow path 4 and cause discharge failure.
  • the ink remaining in the liquid reservoir is not completely removed even if the ink is sufficiently washed at the time of ink replacement, and flows out little by little in the process of repeating ejection / stop. come. This phenomenon is particularly noticeable when the ink is changed from low-brightness ink such as cyan or black to high-brightness white-yellow ink.
  • ink supply ports are provided at two locations on both sides of the common ink chamber, and by supplying ink, the dead flow area disappears, and the liquid reservoir Is also canceled.
  • the distance and time until ink is supplied to each ink flow path 4 is shortened, and even when ink with high viscosity is used, ink can be supplied quickly. High speed recording is possible.
  • FIG. 6 shows another embodiment of the ink jet head according to the present invention, in which two ink supply ports are provided on the surface facing the nozzle surface of the ink chamber.
  • the ink supply port when the ink supply port is provided, it is more preferable to provide the ink supply port at a location closer to the corner where the liquid pool easily occurs.
  • it is also effective to eliminate the liquid pool by providing two ink supply ports on the upper surface of the cover plate 6.
  • the ink used in the present invention is not particularly limited as long as it is a known ink-jet ink, but can be printed on a non-ink-absorbing substrate, which is difficult to form an image with a conventional ink-jet ink. This is particularly effective when actinic ray curable ink, which has been attracting attention as an ink, is used.
  • Such actinic ray curable ink is an ultraviolet curable ink (hereinafter also referred to as UV ink) having a property of being cured by irradiation with actinic rays such as ultraviolet rays, for example. It contains a polymerizable compound, a photopolymerization initiator, and a colorant.
  • UV ink ultraviolet curable ink
  • the UV ink is roughly classified into a radically polymerizable ink containing a radically polymerizable compound and a cationically polymerizable ink containing a cationically polymerizable compound as a polymerizable compound.
  • the present invention can be applied as a UV ink used in the present invention, and a hybrid UV ink in which a radical polymerizable ink and a cationic polymerizable ink are combined may be applied as a UV ink used in the present invention.
  • the cationic polymerizable ink which has less or no inhibition of the polymerization reaction by oxygen, has a higher curing sensitivity and is more versatile. Therefore, in the present invention, a cationic polymerizable ink is particularly used. It is preferable.
  • the cationically polymerizable ink used in the present invention specifically includes at least a cationically polymerizable compound such as an oxetane compound, an epoxy compound, and a butyl ether compound, a photopower thione polymerization initiator, and a colorant. As mentioned above, it is a mixture that has the property of being cured by irradiation with ultraviolet rays.
  • the ink in the present invention preferably has a viscosity of 7-: lOOmPa's at 25 ° C.
  • lOOmPa's a viscosity of 7-: lOOmPa's at 25 ° C.
  • the present invention can be particularly suitably applied when using an ink containing a pigment having a specific gravity of 2.0 or more, and examples of such a pigment include inorganic pigments.
  • the inorganic white pigment used in the present invention is only required to make the ink composition white.
  • examples of such inorganic white pigment include sulfates of alkaline earth metals such as barium sulfate, calcium carbonate, and the like.
  • examples thereof include silicas such as alkaline earth metal carbonates, finely divided key acids, and synthetic silicates, calcium silicates, anoremina, alumina hydrates, titanium oxides, zinc oxides, talc, and trays.
  • titanium oxide is preferable as a white pigment having good concealability, colorability, and dispersed particle size.
  • the ink jet recording head of FIG. 1 (this is a comparative example) is used, and the UV ink is ejected as droplets on the substrate and drawn. Thereafter, the ink is cured by irradiating with ultraviolet rays.
  • the ink emission conditions it is preferable from the viewpoint of the emission stability that the ink is heated to 35 to: 100 ° C, and the ink viscosity is lowered and emitted.
  • Actinic ray curable inks are generally more viscous than common water-based inks, and are therefore susceptible to viscosity fluctuations due to temperature fluctuations. This variation in viscosity greatly affects the droplet size and droplet ejection speed as they are, and causes image quality degradation. Therefore, it is necessary to keep the ink temperature as constant as possible.
  • the thermal recording head preferably has a working valve as described in JP-A-9323420 for emission.
  • the heads described in European Patent A277, 703, European Patent A278, 590 and the like can be used.
  • the inkjet head preferably has a temperature control function so that the temperature of the ink can be controlled.
  • the emission temperature is set so that the viscosity at the time of emission is 5 to 30 mPa's, and to control the ink temperature so that the fluctuation range of the viscosity is within ⁇ 5%.
  • the drive frequency is preferably 5 to 500 kHz.
  • the ink droplet amount in order to obtain a high-definition image, it is preferable to set the ink droplet amount to 2 to 20 pl. Since the ink of the present invention has good emission characteristics, even if the amount of droplets is small, a good image can be obtained without causing nozzle clogging, dot bending, satellites, or the like.
  • a light source that generates ultraviolet rays or visible rays having a wavelength of 180 to 500 nm is effective.
  • Metal halide lamps chemical lamps, black light lamps, mercury-xenon lamps, excimer lamps, short arc lamps, helium 'power dominium lasers, argon lasers, excimer lasers and sunlight. It is also possible to cure using two types of light sources with different light sources and illuminance.
  • a light source having a peak illuminance at an absorption wavelength of ink of 1 to 500 mW / cm 2 is preferable. Since such a light source can perform a sufficient curing reaction, it is relatively inexpensive and a small ultraviolet irradiation device can be used, which is advantageous in terms of cost.
  • Epoxy resin (Celoxide 2021P: manufactured by Daicel Chemical Co., Ltd.) 18.1 parts by mass Oxetane compound (OXT221: manufactured by Toa Gosei) 72.5 parts by mass Pigment (Pigment Blue 15: 4) 2.5 parts by mass
  • Pigment dispersant (Ajisper PB822: Ajinomoto Fine Techno) 1.0 part by weight Surfactant (KF351: Shin-Etsu Silicone) 0.8 part by weight
  • Epoxy resin (Celoxide 2021P: manufactured by Daicel Chemical Co., Ltd.) 15 ⁇ 6 parts by mass Oxetane compound (OXT221: manufactured by Toa Gosei) 62. 3 parts by mass Pigment (anatase type titanium oxide) 15 parts by mass Pigment dispersant (Ajisper PB822: Ajinomoto Fine Techno) 1.2 parts by weight Surfactant (KF351: Shin-Etsu Silicone) 0.8 parts by weight
  • the actinic radiation curable cyan ink (hereinafter referred to as cyan ink) was loaded into an ink jet printer equipped with the inkjet head shown in FIG. 5 (the present invention) and FIG. 4 (comparative), and continuous emission was performed (image formation). ).
  • the ink supply system of the ink jet printer has an ink tank, a supply pipe, a front chamber ink tank immediately before the head, a pipe with a filter, an ink jet head force, and heat insulation from the front chamber tank to the head portion.
  • the inkjet head was driven to discharge at a resolution of 720 x 720dpi (dpi represents the number of dots per 54cm).
  • the cyan ink was removed and replaced with the above-mentioned actinic ray curable white ink (hereinafter referred to as white ink). After the white ink was sufficiently flowed, emission was performed in the same manner (image formation).

Abstract

An ink jet head provided with a plurality of nozzles for jetting an ink, a plurality of ink flow paths which communicate with the plurality of nozzles and are arranged as grooves on a piezoelectric ceramic, and a common ink chamber for distributing the ink to the ink flow paths and filling the ink flow paths with the ink is characterized in that two or more ink supply ports are provided for supplying the common ink chamber with the ink from an ink supplying source.

Description

明 細 書  Specification
インクジェットヘッドおよび画像形成方法  Ink jet head and image forming method
技術分野  Technical field
[0001] 本発明は、インクジェットヘッド、およびそれを用いた画像形成方法に関する。  The present invention relates to an inkjet head and an image forming method using the same.
背景技術  Background art
[0002] 近年、インクジェットヘッドおよびそれを用いた画像形成方法において、インクジエツ トヘッドには、周知の通り圧電部材などによりインク流路に供給されたインクにェネル ギーを付与して、インク流路の先端に設けられたノズル力 インク滴を吐出させるもの (ドロップ.オン.デマンド型)など種々の形式のものがある。  In recent years, in an ink jet head and an image forming method using the same, the ink jet head is imparted with energy to the ink supplied to the ink flow path by a piezoelectric member or the like, as is well known, and the tip of the ink flow path There are various types such as those that eject ink droplets (drop-on-demand type).
[0003] その中でも最近は、圧電材料そのものにインク流路を形成し、インク流路の隔壁を 振動させることによって、ノズル力 インク滴を吐出させるようにしたせん断モード型の インクジェットヘッドが提案されており、小型化や高速化に有利である(例えば、特許 文献 1参照)。  [0003] Among these, recently, there has been proposed a shear mode type ink jet head in which an ink flow path is formed in the piezoelectric material itself and the partition wall of the ink flow path is vibrated to eject nozzle force ink droplets. Therefore, it is advantageous for miniaturization and high speed (for example, see Patent Document 1).
[0004] 図 1は従来のせん断モード型インクジェットヘッドの構造を示す斜視図で、図 2はそ の時の側断面図である。図 1、図 2において 1は圧電性セラミック基板、 2はノズノレプレ ート、 3はノズノレ、 4はインク流路(溝)、 5は側壁、 6はカバープレート、 7は共通インク 室、 8はインク供給口である。  FIG. 1 is a perspective view showing a structure of a conventional shear mode type ink jet head, and FIG. 2 is a side sectional view at that time. 1 and 2, 1 is a piezoelectric ceramic substrate, 2 is a nose plate, 3 is a nose plate, 4 is an ink channel (groove), 5 is a side wall, 6 is a cover plate, 7 is a common ink chamber, and 8 is ink. Supply port.
[0005] 圧電性セラミック基板 1にはダイヤモンドブレード等により切削加工され、複数のイン ク流路 (溝) 4が全て同じ形状で平行に形成され、インク流路 (溝) 4の側面となる側壁 5には矢印方向に分局されている。インク流路 (溝) 4の内面には、金属電極 9がスパ ッタリング等によって形成されている。カバープレート 6はセラミック材料又は樹脂材 料等から形成され、研削または切削加工等によってインク供給口 8及び共通インク室 7が形成されている。そして、圧電性セラミック基板 1のインク流路 (溝) 4が加工された 面とカバープレート 6の共通インク室 7が加工された面とがエポキシ系接着剤等で接 合されることにより、インク流路が形成される。供給インク室 7には図示していなレ、イン ク供給源 (インクタンク)力 インク供給口 8を介してインクが流れ、各インク流路 4にィ ンクが満たされる。 [0006] インク流路 (溝) 4からインクを出射するにあたり、金属電極に駆動電圧が印加され 側壁 5が急激に変形し、ここの変形によってインク流路 (溝) 4の容積が減少してインク 圧力が急速に増大し、圧力波が発生して、インク流路 (溝) 4に連通するノズル 3から インク滴が噴射される。駆動電圧の印加が停止されると、側壁 5が変形前の位置に徐 々に戻るため、インク流路 (溝)内のインク圧力が徐々に低下する。そしてインク供給 源からインク供給口 8および共通インク室 7を通してインク流路 (溝) 4にインクが供給 される。 The piezoelectric ceramic substrate 1 is cut by a diamond blade or the like, and a plurality of ink flow paths (grooves) 4 are all formed in parallel with the same shape. 5 is divided in the direction of the arrow. A metal electrode 9 is formed on the inner surface of the ink flow path (groove) 4 by sputtering or the like. The cover plate 6 is formed of a ceramic material or a resin material, and an ink supply port 8 and a common ink chamber 7 are formed by grinding or cutting. Then, the surface of the piezoelectric ceramic substrate 1 where the ink flow path (groove) 4 is processed and the surface of the cover plate 6 where the common ink chamber 7 is processed are bonded with an epoxy adhesive or the like. A flow path is formed. Ink supply source (ink tank) force not shown in the supply ink chamber 7 Ink flows through the ink supply port 8, and each ink flow path 4 is filled with ink. When ejecting ink from the ink flow path (groove) 4, a drive voltage is applied to the metal electrode, and the side wall 5 is suddenly deformed. This deformation reduces the volume of the ink flow path (groove) 4. The ink pressure rapidly increases, a pressure wave is generated, and ink droplets are ejected from the nozzle 3 communicating with the ink flow path (groove) 4. When the application of the drive voltage is stopped, the side wall 5 gradually returns to the position before the deformation, so that the ink pressure in the ink flow path (groove) gradually decreases. Then, ink is supplied from the ink supply source to the ink flow path (groove) 4 through the ink supply port 8 and the common ink chamber 7.
[0007] 上記の構成のインクジェットヘッドは機能性材料である圧電素子を流路基板として 用いるものであり、流路基板自身が圧電発生手段となっているため、流路ならびにノ ズノレの高密度化を可能にしてレ、る。  [0007] The inkjet head configured as described above uses a piezoelectric element, which is a functional material, as a flow path substrate, and the flow path substrate itself serves as a piezoelectric generating means, so that the flow path and the nozzle density are increased. Let's make it possible.
[0008] また、近年インクジェット用インクとして、速乾性、滲み防止、インク吸収性の無い記 録媒体への記録が出来る点等で、活性光線硬化型組成物から成るインクを用いたィ ンクジェット方式が注目されつつある。 (例えば、特許文献 1〜6参照。)  [0008] In recent years, as an inkjet ink, an ink jet method using an ink comprising an actinic ray curable composition in that it can be recorded on a recording medium having fast drying, prevention of bleeding, and no ink absorption. Is getting attention. (For example, see Patent Documents 1 to 6.)
し力しながら、このような活性光線硬化型インクジェット用インクに用いられる素材は 比較的粘度が高いため、インク供給源力 共通インク室内にインクを供給する場合、 一箇所からの供給では死流域 (流れが淀む点)が多くなつたり、流速が遅いためイン ク供給口から最も遠いノズノレへのインク補充時間が長くなり高速記録の障害になって しまう。  However, since the material used for such actinic radiation curable ink jet ink has a relatively high viscosity, when supplying ink into the common ink chamber, it is a dead flow area ( As the flow becomes stagnant) and the flow speed is slow, the ink replenishment time to the nozzle farthest from the ink supply port becomes long, which hinders high-speed recording.
[0009] インクジェットヘッドにおいてマ二ホールドの両端に開口部を設け、生産時のヘッド 内洗浄の効率化を目的としたもの(例えば、特許文献 7参照)があるが、この開口部 は洗浄液の流入口と排出口であり、ノズルからインクを安定に出射させる目的とは異 なる。  Some inkjet heads are provided with openings at both ends of the manifold for the purpose of improving the efficiency of cleaning in the head during production (for example, see Patent Document 7). These are the inlet and outlet, which are different from the purpose of stably ejecting ink from the nozzle.
[0010] インクヘッドにインクの出入り口を 2箇所設けヘッド内のインクをインク循環通路の内 外に移動させインクの均一化を図っているもの(例えば、特許文献 8参照)があるが、 これもインクを通過させることを目的としており、共通インク室から各ノズルへ安定にィ ンクを供給し難い。また高粘度インクを用レ、た場合は、循環の流路が長くある分、負 荷も大きくなる。  [0010] There are two ink inlets / outlets provided in the ink head to move the ink in the head into and out of the ink circulation path to make the ink uniform (for example, see Patent Document 8). The purpose is to allow ink to pass through, and it is difficult to stably supply ink from the common ink chamber to each nozzle. In addition, when high viscosity ink is used, the longer the circulation path, the greater the load.
[0011] また、活性光線硬化型インクジェット用インクを用いて、インク吸収性の無い透明記 録媒体へ印字する場合、視認性の確保から白インクの使用が望まれ、白インクの顔 料として酸化チタンのような無機白色顔料が用いられる力 これらは比重が重ぐイン ク化したときに沈降しやすい特徴を有している。そのようなインクをインクヘッドに供給 する場合、インク室内で死流域があると液溜りが発生し、沈殿物が溜まりやすくなつて しまい、長時間の使用において稼動 Z停止を繰り返すうちに顔料濃度の均一性が保 てなくなってしまう。 [0011] In addition, the actinic ray curable inkjet ink is used to make a transparent recording having no ink absorbability. When printing on recording media, it is desirable to use white ink to ensure visibility, and the power to use inorganic white pigments such as titanium oxide as white ink pigments. It has the characteristic of being easily settled. When supplying such ink to the ink head, if there is a dead flow area in the ink chamber, a liquid pool will be generated, and the precipitate will easily accumulate. Uniformity cannot be maintained.
[0012] 従って、インクジェットヘッドにおいて共通インク室に液溜りが発生しないようにイン クを供給することで、高粘度インクや沈降性の高いインクを用いた場合でもインクの吐 出不良やインク交換時のコンタミが防止でき、また、インク供給が迅速になり、高速記 録が可能になるインクジェットヘッドおよびそれを用いた画像形成方法の開発が要望 されていた。  [0012] Therefore, by supplying ink so that liquid pool does not occur in the common ink chamber in the inkjet head, even when high viscosity ink or ink with high sedimentation property is used, ink discharge failure or ink replacement There has been a demand for the development of an inkjet head and an image forming method using the inkjet head that can prevent the contamination of the ink jet ink, and can supply the ink quickly and enable high-speed recording.
特許文献 1 :特開平 6— 234216号公報  Patent Document 1: JP-A-6-234216
特許文献 2 :W〇99/29787号  Patent Document 2: W〇99 / 29787
特許文献 3:特表 2000— 504778号公報  Patent Document 3: Japanese Patent Publication No. 2000-504778
特許文献 4:特開 2001— 220526号公報  Patent Document 4: Japanese Patent Laid-Open No. 2001-220526
特許文献 5 :特開 2002— 188025号公報  Patent Document 5: Japanese Unexamined Patent Application Publication No. 2002-188025
特許文献 6 :特開 2003— 55449号公報  Patent Document 6: Japanese Unexamined Patent Publication No. 2003-55449
特許文献 7:特開 2004— 90469号公報  Patent Document 7: Japanese Unexamined Patent Application Publication No. 2004-90469
特許文献 8 :特許第 3507169号公報  Patent Document 8: Japanese Patent No. 3507169
発明の開示  Disclosure of the invention
[0013] 本発明は、上記課題に鑑みなされたものであり、本発明の目的は、インクジェットへ ッドにおいて共通インク室に液溜りが発生しないようにインクを供給することで、高粘 度インクや沈降性の高いインクを用いた場合でもインクの吐出不良やインク交換時の コンタミが防止でき、また、インク供給が迅速になり、高速記録が可能になるインクジ エツトヘッドおよびそれを用いた画像形成方法を提供することにある。  [0013] The present invention has been made in view of the above problems, and an object of the present invention is to supply high-viscosity ink by supplying ink so that a liquid pool does not occur in a common ink chamber in an inkjet head. Ink jet head that can prevent ink discharge failure and contamination during ink replacement even when ink with high sedimentation property is used, ink supply is quick, and high-speed recording is possible, and image forming method using the same Is to provide.
[0014] 上記目的を達成するための、本発明の一つの態様は、インクを吐出する複数のノズ ルと、該複数のノズルに連通し、圧電性セラミックに溝として設けられた複数のインク 流路と、該インク流路にインクを分配充填する共通インク室を有するインクジェットへッ ドにおレ、て、該共通インク室にインク供給源力 インクを供給するインク供給口を 2箇 所以上設けることを特徴とするインクジェットヘッドとそれを用いた画像形成方法にあ る。 [0014] In order to achieve the above object, one aspect of the present invention includes a plurality of nozzles that eject ink, and a plurality of ink streams that communicate with the plurality of nozzles and that are provided as grooves in the piezoelectric ceramic. An inkjet head having a path and a common ink chamber for distributing and filling ink in the ink flow path. An ink jet head and an image forming method using the ink jet head are provided with at least two ink supply ports for supplying ink to the common ink chamber.
図面の簡単な説明  Brief Description of Drawings
[0015] [図 1]従来のせん断モード型インクジェットヘッドの構造を示す斜視図。  FIG. 1 is a perspective view showing the structure of a conventional shear mode type ink jet head.
[図 2]図 1のせん断モード型インクジェットヘッドの構造を示す側断面図。  2 is a side sectional view showing the structure of the shear mode type ink jet head of FIG.
[図 3]従来のせん断型インクジェットヘッドを示す断面図。  FIG. 3 is a cross-sectional view showing a conventional shear-type inkjet head.
[図 4]インク供給口 8が片側面のみにある場合、の共通インク室内でのインクの流れを 示す説明図。  FIG. 4 is an explanatory diagram showing the flow of ink in the common ink chamber when the ink supply port 8 is only on one side.
[図 5]インク供給口を共通インク室の両側面の 2箇所に設けた本発明のインクジェット ヘッドの形態の一例を示す断面図。  FIG. 5 is a cross-sectional view showing an example of an embodiment of an ink jet head of the present invention in which ink supply ports are provided at two locations on both side surfaces of a common ink chamber.
[図 6]インク室のノズノレ面と対向する面に 2箇所インク供給口を設けた本発明のインク ジェットヘッドの形態の一例を示す断面図。  FIG. 6 is a cross-sectional view showing an example of the form of the ink jet head of the present invention in which two ink supply ports are provided on the surface of the ink chamber facing the nozzle surface.
[図 7]カバープレート 6の上面に 2箇所インク供給口を設けた本発明のインクジェットへ ッドの形態の一例を示す断面図。  FIG. 7 is a cross-sectional view showing an example of the form of the ink jet head of the present invention in which two ink supply ports are provided on the upper surface of the cover plate 6.
符号の説明  Explanation of symbols
[0016] 1 圧電性セラミック基板 [0016] 1 Piezoelectric ceramic substrate
2 ノズルプレート  2 Nozzle plate
3 ノズル  3 nozzles
4 インク流路 (溝)  4 Ink channel (groove)
5 側壁  5 Side wall
6 カバープレート  6 Cover plate
7 共通インク室  7 Common ink chamber
8 インク供給口  8 Ink supply port
9 金属電極  9 Metal electrode
10 接着剤等  10 Adhesive etc.
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0017] 本発明の上記目的は、下記の構成により達成される。 [0018] (1)インクを吐出する複数のノズルと、該複数のノズノレに連通し、圧電性セラミックに 溝として設けられた複数のインク流路と、該インク流路にインクを分配充填する共通ィ ンク室を有するインクジェットヘッドにおいて、該共通インク室にインク供給源からイン クを供給するインク供給口を 2箇所以上設けることを特徴とするインクジェットヘッド。 The above object of the present invention is achieved by the following configurations. [0018] (1) A plurality of nozzles that eject ink, a plurality of ink channels that communicate with the plurality of nozzles, and are provided as grooves in the piezoelectric ceramic, and a common ink that distributes and fills the ink channels An inkjet head having an ink chamber, wherein the common ink chamber is provided with two or more ink supply ports for supplying ink from an ink supply source.
[0019] (2)インクを吐出する複数のノズルと、該複数のノズノレに連通し、圧電性セラミックに 溝として設けられた複数のインク流路と、該インク流路にインクを分配充填する共通ィ ンク室を有するインクジェットヘッドを用レ、、インクを吐出し、被記録媒体上に画像を 形成する画像形成方法において、該共通インク室にインク供給源からインクを供給す るインク供給口を 2箇所以上設けるインクジェットヘッドを用レ、、 25°Cで粘度が 7〜: 10 OmPa ' sのインクを吐出し、被記録媒体上に画像を形成することを特徴とする画像形 成方法。  [0019] (2) A plurality of nozzles that eject ink, a plurality of ink channels that communicate with the plurality of nozzles, and are provided as grooves in the piezoelectric ceramic, and a common ink that distributes and fills the ink channels In an image forming method for forming an image on a recording medium by using an ink jet head having an ink chamber, an ink supply port for supplying ink from an ink supply source to the common ink chamber is provided. An image forming method comprising: forming an image on a recording medium by ejecting an ink jet head provided at a plurality of positions, and ejecting an ink having a viscosity of 7 to 10 OmPa's at 25 ° C.
[0020] (3)インクを吐出する複数のノズルと、該複数のノズノレに連通し、圧電性セラミックに 溝として設けられた複数のインク流路と、該インク流路にインクを分配充填する共通ィ ンク室を有するインクジェットヘッドを用レ、、インクを吐出し、被記録媒体上に画像を 形成する画像形成方法において、該共通インク室にインク供給源からインクを供給す るインク供給口を 2箇所以上設けるインクジェットヘッドを用い、比重が 2. 0以上の顔 料を含有したインクを吐出し、被記録媒体上に画像を形成することを特徴とする画像 形成方法。  [0020] (3) A plurality of nozzles that eject ink, a plurality of ink channels that communicate with the plurality of nozzles, and are provided as grooves in the piezoelectric ceramic, and a common ink that distributes and fills the ink channels In an image forming method for forming an image on a recording medium by using an ink jet head having an ink chamber, an ink supply port for supplying ink from an ink supply source to the common ink chamber is provided. An image forming method comprising: forming an image on a recording medium by ejecting ink containing a pigment having a specific gravity of 2.0 or more using an ink jet head provided at more than one location.
[0021] (4)前記比重が 2. 0以上の顔料が、無機白色顔料であることを特徴とする項 3に記 載の画像形成方法。  [0021] (4) The image forming method according to item 3, wherein the pigment having a specific gravity of 2.0 or more is an inorganic white pigment.
[0022] (5)前記比重が 2. 0以上の顔料を含有したインク力 25°Cで粘度が 7〜100mPa ' sであることを特徴とする項 3または 4に記載の画像形成方法。  [0022] (5) The image forming method according to item 3 or 4, wherein the ink strength is 25 ° C. and the viscosity is 7 to 100 mPa ′s containing a pigment having a specific gravity of 2.0 or more.
[0023] 以下、本発明を実施するための最良の形態について説明するが、本発明はこれら に限定されない。 [0023] The best mode for carrying out the present invention will be described below, but the present invention is not limited thereto.
[0024] 本発明のインクジェットヘッドは、インクを吐出する複数のノズノレと、該複数のノズノレ に連通し、圧電性セラミックに溝として設けられた複数のインク流路と、該インク流路 にインクを分配充填する共通インク室を有するインクジェットヘッドにおいて、該共通 インク室にインク供給源力 インクを供給するインク供給口を 2箇所以上設けることを 一つの特徴とする。 [0024] An inkjet head of the present invention includes a plurality of nozzles that eject ink, a plurality of ink channels that communicate with the plurality of nozzles, and that are provided as grooves in a piezoelectric ceramic, and ink that flows into the ink channels. In an inkjet head having a common ink chamber for distributing and filling, the ink supply source for the common ink chamber should be provided with two or more ink supply ports for supplying ink. One feature.
[0025] 本発明において、インク供給口は 2箇所以上設けることが特徴であり、 2〜4箇所に 設けることがより好ましい。 4箇所より多いとヘッドの構成が複雑で取り扱いが難しくな る懸念がある。また、設置場所としては、死流域ができないように設けることが好ましく 、例えば、死流域の出来やすいヘッドの隅などの近くに設置することがより好ましい。  In the present invention, the ink supply port is characterized by being provided at two or more locations, and more preferably at 2 to 4 locations. If there are more than four locations, there is a concern that the configuration of the head is complex and difficult to handle. Further, the installation location is preferably set so that there is no dead flow area, and for example, it is more preferable to install near the corner of the head where the dead flow area is easily formed.
[0026] 以下、本発明の実施の形態を図面を参照しながら詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0027] 図 3は従来のせん断型インクジェットヘッドを示す図であり、インク供給口 8が中心の 1箇所にある場合、また、図 4はインク供給口 8が片側面のみにある場合、の共通イン ク室内でのインクの流れを示す説明図である。これらの場合、インク供給口 8からイン クが供給されると、インクは放射状に広がりながらインク流路 4へ流れていく。この時、 共通インク室のインク流路 4と対向面の隅 (A)に、殆ど流速のない死流域ができ液溜 りが発生する。ここには気泡や不純物、沈殿物が溜まりやすぐ長時間使用している とあるきつかけでそれらがまとまってインク流路 4に流れ出し吐出不良を起こしてしまう FIG. 3 is a diagram showing a conventional shear-type ink jet head, and is common when the ink supply port 8 is at one central position, and FIG. 4 is common when the ink supply port 8 is only on one side. FIG. 5 is an explanatory diagram showing the flow of ink in the ink chamber. In these cases, when ink is supplied from the ink supply port 8, the ink flows into the ink flow path 4 while spreading radially. At this time, a dead flow area with almost no flow velocity is created in the corner (A) of the opposite surface to the ink flow path 4 of the common ink chamber, and a liquid pool is generated. Air bubbles, impurities, and sediment accumulate here, and if they are used for a long time, they gather together and flow into the ink flow path 4 and cause discharge failure.
[0028] また、 1つのヘッドを数色で兼用する場合、インク交換時に充分、洗浄を行っても、 液溜りに残留したインクが除き切れず、出射/停止を繰り返す過程で少しずつ流出 してくる。この現象はシアンやブラックなどの明度の低いインクから明度の高い白ゃィ エローのインクに交換したときに、特に目立ち色濁りの原因となる。 [0028] Also, when one head is used in several colors, the ink remaining in the liquid reservoir is not completely removed even if the ink is sufficiently washed at the time of ink replacement, and flows out little by little in the process of repeating ejection / stop. come. This phenomenon is particularly noticeable when the ink is changed from low-brightness ink such as cyan or black to high-brightness white-yellow ink.
[0029] これに対し、本発明においては、例えば、図 5に示すようにインク供給口を共通イン ク室の両側面の 2箇所に設け、インクを供給することで死流域がなくなり、液溜りも解 消される。また、 2箇所力 供給することにより、各インク流路 4にインクが供給されるま での距離および時間が短くなり、粘度の高レ、インクを用いた場合でも、迅速にインク 供給ができ、高速記録が可能となる。  On the other hand, in the present invention, for example, as shown in FIG. 5, ink supply ports are provided at two locations on both sides of the common ink chamber, and by supplying ink, the dead flow area disappears, and the liquid reservoir Is also canceled. In addition, by supplying force at two points, the distance and time until ink is supplied to each ink flow path 4 is shortened, and even when ink with high viscosity is used, ink can be supplied quickly. High speed recording is possible.
[0030] また、図 6は本発明におけるインクジェットヘッドの別の形態を示し、インク室のノズ ル面と対向する面にインク供給口を 2箇所設けた。本発明におレ、てインク供給口を設 ける場合、液溜りが起きやすい隅により近い個所に設けることがより望ましい。また、 図 7に示すようにカバープレート 6の上面にインク供給口を 2箇所設けることも液溜り 解消には有効である。 [0031] 本発明に用いられるインクとしては、公知のインクジェット用インクであれば特に限 定されなレ、が、従来のインクジェットインクでは画像形成が難しかったインク吸収性の ない基材にも印字可能として注目を集めている活性光線硬化型インクを用いた場合 、特に有効である。 FIG. 6 shows another embodiment of the ink jet head according to the present invention, in which two ink supply ports are provided on the surface facing the nozzle surface of the ink chamber. In the present invention, when the ink supply port is provided, it is more preferable to provide the ink supply port at a location closer to the corner where the liquid pool easily occurs. In addition, as shown in FIG. 7, it is also effective to eliminate the liquid pool by providing two ink supply ports on the upper surface of the cover plate 6. [0031] The ink used in the present invention is not particularly limited as long as it is a known ink-jet ink, but can be printed on a non-ink-absorbing substrate, which is difficult to form an image with a conventional ink-jet ink. This is particularly effective when actinic ray curable ink, which has been attracting attention as an ink, is used.
[0032] そのような活性光線硬化型インクは、例えば紫外線のような活性光線の照射により 硬化する性質を具備する紫外線硬化性インク(以下、 UVインクともいう)であり、主成 分として、少なくとも重合性化合物と、光重合開始剤と、着色剤とを含むものである。  [0032] Such actinic ray curable ink is an ultraviolet curable ink (hereinafter also referred to as UV ink) having a property of being cured by irradiation with actinic rays such as ultraviolet rays, for example. It contains a polymerizable compound, a photopolymerization initiator, and a colorant.
[0033] 上記 UVインクは、重合性化合物として、ラジカル重合性化合物を含むラジカル重 合性インクとカチオン重合系化合物を含むカチオン重合性インクとに大別されるが、 その両系の UVインクが本発明に用いられる UVインクとしてそれぞれ適用可能であり 、ラジカル重合性インクとカチオン重合性インクとを複合させたハイブリッド型 UVイン クを本発明に用いられる UVインクとして適用してもよレ、。  [0033] The UV ink is roughly classified into a radically polymerizable ink containing a radically polymerizable compound and a cationically polymerizable ink containing a cationically polymerizable compound as a polymerizable compound. The present invention can be applied as a UV ink used in the present invention, and a hybrid UV ink in which a radical polymerizable ink and a cationic polymerizable ink are combined may be applied as a UV ink used in the present invention.
[0034] し力 ながら、酸素による重合反応の阻害が少ない又は無いカチオン重合性インク のほうが、硬化感度が高ぐ機能性'汎用性に優れるため、本発明では特に、カチォ ン重合性インクを用いることが好ましい。  [0034] However, the cationic polymerizable ink, which has less or no inhibition of the polymerization reaction by oxygen, has a higher curing sensitivity and is more versatile. Therefore, in the present invention, a cationic polymerizable ink is particularly used. It is preferable.
[0035] なお、本発明に用いられるカチオン重合性インクは、具体的に、少なくともォキセタ ン化合物、エポキシ化合物、ビュルエーテル化合物等のカチオン重合性化合物と、 光力チオン重合開始剤と、着色剤を含む混合物であり、上記の通り、紫外線の照射 により硬化する性質を具備するものである。  [0035] The cationically polymerizable ink used in the present invention specifically includes at least a cationically polymerizable compound such as an oxetane compound, an epoxy compound, and a butyl ether compound, a photopower thione polymerization initiator, and a colorant. As mentioned above, it is a mixture that has the property of being cured by irradiation with ultraviolet rays.
[0036] 本発明におけるインクは粘度が 25°Cにおいて 7〜: lOOmPa' sであることが好ましい 。これにより、吸収性のある基材でもインクの浸透を防ぎ、未硬化の重合性化合物の 低減や臭気低減が可能となり、着弾時のドット滲みを抑えることが出来る。また、高粘 度インクを用いることで表面張力の違う基材間でも同じようなドットが形成されるため、 同じような画質が得られる。該粘度が 7mPa' s未満では、滲み防止効果が小さい懸 念がある。一方、 lOOmPa' sより大きいと、インク液の供給に問題が生じる懸念がある  [0036] The ink in the present invention preferably has a viscosity of 7-: lOOmPa's at 25 ° C. As a result, ink penetration can be prevented even with an absorbent substrate, uncured polymerizable compounds can be reduced and odors can be reduced, and dot bleeding upon landing can be suppressed. In addition, by using high viscosity ink, similar dots are formed between substrates with different surface tensions, so that similar image quality can be obtained. If the viscosity is less than 7 mPa's, there is a concern that the effect of preventing bleeding is small. On the other hand, if it is larger than lOOmPa's, there is a concern that a problem may occur in the supply of ink liquid.
[0037] 本発明は、比重が 2. 0以上の顔料を含有したインクを使用する場合に特に好適に 適用されることが出来、そのような顔料としては無機顔料が挙げられる。 [0038] また、本発明に用いられる無機白色顔料はインク組成物を白色にするものであれ ばよぐそのようなものとしては、硫酸バリウム等のアルカリ土類金属の硫酸塩、炭酸 カルシウム等のアルカリ土類金属の炭酸塩、微粉ケィ酸、合成ケィ酸塩等のシリカ類 、ケィ酸カルシウム、ァノレミナ、アルミナ水和物、酸化チタン、酸化亜鉛、タルク、タレ ィ等が挙げられる。特に酸化チタンは隠蔽性および着色性、分散粒径が好ましい白 色顔料として好ましい。 [0037] The present invention can be particularly suitably applied when using an ink containing a pigment having a specific gravity of 2.0 or more, and examples of such a pigment include inorganic pigments. [0038] The inorganic white pigment used in the present invention is only required to make the ink composition white. Examples of such inorganic white pigment include sulfates of alkaline earth metals such as barium sulfate, calcium carbonate, and the like. Examples thereof include silicas such as alkaline earth metal carbonates, finely divided key acids, and synthetic silicates, calcium silicates, anoremina, alumina hydrates, titanium oxides, zinc oxides, talc, and trays. In particular, titanium oxide is preferable as a white pigment having good concealability, colorability, and dispersed particle size.
[0039] 次いで、画像形成方法の実施形態を説明するが、本発明の態様はこれに限定され ない。  Next, an embodiment of the image forming method will be described, but the aspect of the present invention is not limited to this.
[0040] 本発明における画像形成方法の実施形態の一例としては、例えば、図 1のインクジ エツト記録ヘッド(これは比較例)を用い、基材上に上記 UVインクを液滴として出射、 描画した後、紫外線を照射してインクを硬化させる。  As an example of the embodiment of the image forming method in the present invention, for example, the ink jet recording head of FIG. 1 (this is a comparative example) is used, and the UV ink is ejected as droplets on the substrate and drawn. Thereafter, the ink is cured by irradiating with ultraviolet rays.
[0041] インクの出射条件としては、インクを 35〜: 100°Cに加熱し、インク粘度を下げて出射 すること力 出射安定性の点で好ましい。活性光線硬化型インクは、概して一般の水 性インクより粘度が高いため、温度変動による粘度変動を受けやすい。この粘度変動 は、そのまま出射される液滴サイズ、液滴出射速度に大きく影響を与え、画質劣化を 引き起こすため、インク温度をできる限り一定に保つことが必要である。  [0041] As the ink emission conditions, it is preferable from the viewpoint of the emission stability that the ink is heated to 35 to: 100 ° C, and the ink viscosity is lowered and emitted. Actinic ray curable inks are generally more viscous than common water-based inks, and are therefore susceptible to viscosity fluctuations due to temperature fluctuations. This variation in viscosity greatly affects the droplet size and droplet ejection speed as they are, and causes image quality degradation. Therefore, it is necessary to keep the ink temperature as constant as possible.
[0042] 本発明に用いられるインクジェットヘッドのタイプは、公知のものを用いることができ 、コンティニァスタイプ、ドットオンデマンドタイプが使用可能である。ドットオンデマン ドタイプのうち、サーマル型記録ヘッドでは、出射のため、特開平 9 323420号に 記載されているような稼動弁を持つタイプが好ましい。また、ピエゾ型記録ヘッドでは 、例えば、欧州特許 A277, 703号、欧州特許 A278, 590号などに記載されている ヘッドを使うことができる。インクジェットヘッドは、インクの温度が管理できるよう温調 機能を持つものが好ましい。出射時の粘度は、 5〜30mPa' sとなるよう出射温度を設 定し、粘度の変動幅が ± 5%以内になるようインク温度を制御することが好ましい。ま た、駆動周波数としては、 5〜500kHzで稼動することが好ましい。  As the type of the ink jet head used in the present invention, a known type can be used, and a continuous type and a dot on demand type can be used. Among the dot-on-demand types, the thermal recording head preferably has a working valve as described in JP-A-9323420 for emission. In the piezo-type recording head, for example, the heads described in European Patent A277, 703, European Patent A278, 590 and the like can be used. The inkjet head preferably has a temperature control function so that the temperature of the ink can be controlled. It is preferable to set the emission temperature so that the viscosity at the time of emission is 5 to 30 mPa's, and to control the ink temperature so that the fluctuation range of the viscosity is within ± 5%. The drive frequency is preferably 5 to 500 kHz.
[0043] 本発明においては、高精細な画像を得るため、インク液滴量を 2〜20plとすること が好ましい。本発明のインクは、出射特性が良好なため、液滴量が小さくても、ノズル 詰まりやドットの曲がり、サテライト等を生じることなく良好な画像を得ることができる。 [0044] 本発明で用いることのできる活性光線の光源としては、波長 180〜500nmの紫外 線又は可視光線を発生する光源が有効であり、例えば、低圧水銀ランプ、高圧水銀 ランプ、超高圧水銀ランプ、メタルハライドランプ、ケミカルランプ、ブラックライトランプ 、水銀一キセノンランプ、エキシマーランプ、ショートアーク灯、ヘリウム '力ドミニゥムレ 一ザ一、アルゴンレーザー、エキシマーレーザー、太陽光が挙げられる。なお、光源 や照度の異なる 2種類の光源を用いて硬化することも可能である。 [0043] In the present invention, in order to obtain a high-definition image, it is preferable to set the ink droplet amount to 2 to 20 pl. Since the ink of the present invention has good emission characteristics, even if the amount of droplets is small, a good image can be obtained without causing nozzle clogging, dot bending, satellites, or the like. [0044] As an active light source that can be used in the present invention, a light source that generates ultraviolet rays or visible rays having a wavelength of 180 to 500 nm is effective. For example, a low-pressure mercury lamp, a high-pressure mercury lamp, or an ultrahigh-pressure mercury lamp. , Metal halide lamps, chemical lamps, black light lamps, mercury-xenon lamps, excimer lamps, short arc lamps, helium 'power dominium lasers, argon lasers, excimer lasers and sunlight. It is also possible to cure using two types of light sources with different light sources and illuminance.
[0045] 本発明において、紫外線による照射を行う場合、インクの吸収波長におけるピーク 照度が l〜500mW/cm2である光源が好ましい。この様な光源は、十分な硬化反応 を行うことができるため、比較的安価で、小型の紫外線照射装置を用いることができ、 コスト的にも有利である。 In the present invention, when irradiation with ultraviolet rays is performed, a light source having a peak illuminance at an absorption wavelength of ink of 1 to 500 mW / cm 2 is preferable. Since such a light source can perform a sufficient curing reaction, it is relatively inexpensive and a small ultraviolet irradiation device can be used, which is advantageous in terms of cost.
実施例  Example
[0046] 以下、実施例を挙げて本発明を詳細に説明するが、本発明はこれらに限定されな レ、。実施例 1  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. Example 1
〈活性光線硬化型シアンインクおよび活性光線硬化型白インクの作製〉 以下の組成からなる活性光線硬化型シアンインクおよび活性光線硬化型白インク を作製し、インクジェットヘッドの評価に用いた。  <Preparation of actinic ray curable cyan ink and actinic ray curable white ink> An actinic ray curable cyan ink and an actinic ray curable white ink having the following compositions were produced and used for evaluation of an inkjet head.
[0047] 〈活性光線硬化型シアンインク〉 <Actinic ray curable cyan ink>
エポキシ樹脂(セロキサイド 2021P :ダイセルィ匕学製) 18. 1質量部 ォキセタン化合物(OXT221 :東亜合成製) 72. 5質量部 顔料(ピグメントブルー 15 : 4) 2. 5質量部  Epoxy resin (Celoxide 2021P: manufactured by Daicel Chemical Co., Ltd.) 18.1 parts by mass Oxetane compound (OXT221: manufactured by Toa Gosei) 72.5 parts by mass Pigment (Pigment Blue 15: 4) 2.5 parts by mass
顔料分散剤(アジスパー PB822 :味の素ファインテクノ製) 1. 0質量部 界面活性剤 (KF351:信越シリコーン製) 0. 8質量部  Pigment dispersant (Ajisper PB822: Ajinomoto Fine Techno) 1.0 part by weight Surfactant (KF351: Shin-Etsu Silicone) 0.8 part by weight
重合禁止剤(ァミン:トリイソプロパノールァミン) 0. 10質量部 光酸発生剤(SP152 :旭電化工業製) 5質量部  Polymerization inhibitor (Amine: Triisopropanolamine) 0.1 part by mass Photoacid generator (SP152: manufactured by Asahi Denka Kogyo) 5 parts by mass
〈活性光線硬化型白インク〉  <Actinic ray curable white ink>
エポキシ樹脂(セロキサイド 2021P :ダイセルィ匕学製) 15· 6質量部 ォキセタン化合物(OXT221 :東亜合成製) 62. 3質量部 顔料 (アナターゼ型酸化チタン) 15質量部 顔料分散剤(アジスパー PB822 :味の素ファインテクノ製) 1. 2質量部 界面活性剤 (KF351:信越シリコーン製) 0. 8質量部 Epoxy resin (Celoxide 2021P: manufactured by Daicel Chemical Co., Ltd.) 15 · 6 parts by mass Oxetane compound (OXT221: manufactured by Toa Gosei) 62. 3 parts by mass Pigment (anatase type titanium oxide) 15 parts by mass Pigment dispersant (Ajisper PB822: Ajinomoto Fine Techno) 1.2 parts by weight Surfactant (KF351: Shin-Etsu Silicone) 0.8 parts by weight
重合禁止剤(ァミン:トリイソプロパノールァミン) 0. 10質量部 光酸発生剤(SP152 :旭電化工業製) 5質量部 Polymerization inhibitor (Amin: Triisopropanolamine) 0.1 part by mass Photoacid generator (SP152: manufactured by Asahi Denka Kogyo) 5 parts by mass
〈インクジェットヘッドを用いた画像形成〉 <Image formation using inkjet head>
図 5 (本発明)および図 4 (比較)に示したインクジェットヘッドを搭載したインクジエツ トプリンタに、上記活性光線硬化型シアンインク(以下、シアンインクという)を装填し、 連続出射を行った(画像形成)。  The actinic radiation curable cyan ink (hereinafter referred to as cyan ink) was loaded into an ink jet printer equipped with the inkjet head shown in FIG. 5 (the present invention) and FIG. 4 (comparative), and continuous emission was performed (image formation). ).
[0048] 尚、インクジェットプリンタのインク供給系は、インクタンク、供給パイプ、ヘッド直前 の前室インクタンク、フィルター付き配管、インクジェットヘッド力、らなり、前室タンクか らヘッド部分まで断熱して 50°Cの加温を行レ、、インクジェットヘッドは、 12plサイズド ットを 720 X 720dpi (dpiとは 2. 54cm当たりのドット数を表す)の解像度で吐出でき るように駆動した。 [0048] The ink supply system of the ink jet printer has an ink tank, a supply pipe, a front chamber ink tank immediately before the head, a pipe with a filter, an ink jet head force, and heat insulation from the front chamber tank to the head portion. The inkjet head was driven to discharge at a resolution of 720 x 720dpi (dpi represents the number of dots per 54cm).
[0049] その後、シアンインクを抜き、上記活性光線硬化型白インク(以下、白インクという) に入れ替え、白インクを充分に流した後、同様に出射を行った(画像形成)。  [0049] Thereafter, the cyan ink was removed and replaced with the above-mentioned actinic ray curable white ink (hereinafter referred to as white ink). After the white ink was sufficiently flowed, emission was performed in the same manner (image formation).
[0050] その結果、図 4のインクジェットヘッド(比較)を用いた場合では出射直後は白インク が出ていたが、途中から色濁りが発生した。これはヘッド内の共通インク室の隅に残 留していたシアンインクが流速の変動で本流に混ざり込んだためと考えられる。これ に対し、図 5のインクジェットヘッド(本発明)を用いた場合には最後まで色濁りのない 良好な白インクが出射されたことが確認された。  As a result, in the case of using the inkjet head of FIG. 4 (comparative), white ink appeared immediately after emission, but color turbidity occurred midway. This is thought to be because the cyan ink remaining in the corner of the common ink chamber in the head was mixed into the main stream due to fluctuations in the flow velocity. On the other hand, it was confirmed that when the ink jet head shown in FIG. 5 (the present invention) was used, good white ink without color turbidity was emitted to the end.
[0051] 以上、説明したように、本発明(2箇所以上にインク供給口を設けること)によれば、 インクジェットヘッドにおいて共通インク室に液溜りが発生しないようにインクを供給す ることで、高粘度インクや沈降性の高いインクを用いた場合でもインクの吐出不良や インク交換時のコンタミが防止でき、また、インク供給が迅速になり、高速記録が可能 になることがわかる。  [0051] As described above, according to the present invention (providing ink supply ports at two or more locations), by supplying ink so that liquid pool does not occur in the common ink chamber in the inkjet head, It can be seen that even when high viscosity ink or ink with high sedimentation is used, ink ejection failure and contamination during ink replacement can be prevented, ink supply is quick, and high speed recording is possible.
[0052] これにより、高粘度インクや沈降性の高いインクを用いた場合でもインクの吐出不良 やインク交換時のコンタミが防止でき、また、インク供給が迅速になり、高速記録が可 能になるインクジェットヘッドおよびそれを用いた画像形成方法を提供することができ る。 [0052] This makes it possible to prevent ink ejection failure and contamination during ink replacement even when high viscosity ink or highly settled ink is used, and ink supply is quick and high-speed recording is possible. Ink jet head and image forming method using the same can be provided The

Claims

請求の範囲 The scope of the claims
[1] インクを吐出する複数のノズノレと、該複数のノズノレに連通し、圧電性セラミックに溝と して設けられた複数のインク流路と、該インク流路にインクを分配充填する共通インク 室を有するインクジェットヘッドにぉレ、て、該共通インク室にインク供給源力もインクを 供給するインク供給口を 2箇所以上設けることを特徴とするインクジェットヘッド。  [1] A plurality of nozzles that eject ink, a plurality of ink channels that communicate with the plurality of nozzles and are provided as grooves in a piezoelectric ceramic, and a common ink that distributes and fills ink in the ink channels An ink-jet head comprising two or more ink supply ports for supplying ink to the common ink chamber as well as an ink supply source, in comparison with an ink-jet head having a chamber.
[2] インクを吐出する複数のノズノレと、該複数のノズノレに連通し、圧電性セラミックに溝と して設けられた複数のインク流路と、該インク流路にインクを分配充填する共通インク 室を有するインクジェットヘッドを用い、インクを吐出し、被記録媒体上に画像を形成 する画像形成方法において、該共通インク室にインク供給源からインクを供給するィ ンク供給口を 2箇所以上設けるインクジェットヘッドを用いることを特徴とする画像形 成方法。 [2] A plurality of nozzles that eject ink, a plurality of ink channels that communicate with the plurality of nozzles and are provided as grooves in the piezoelectric ceramic, and a common ink that distributes and fills the ink channels with ink In an image forming method for forming an image on a recording medium by using an ink jet head having a chamber, an ink jet having two or more ink supply ports for supplying ink from an ink supply source to the common ink chamber An image forming method using a head.
[3] 前記インクは 25°Cで粘度が 7〜100mPa ' sであることを特徴とする請求の範囲第 2 項に記載の画像形成方法。  3. The image forming method according to claim 2, wherein the ink has a viscosity of 7 to 100 mPa ′s at 25 ° C.
[4] 前記インクは比重が 2. 0以上の顔料を含有したインクであることを特徴とする請求の 範囲第 2項に記載の画像形成方法。 4. The image forming method according to claim 2, wherein the ink is an ink containing a pigment having a specific gravity of 2.0 or more.
[5] 前記比重が 2. 0以上の顔料が、無機白色顔料であることを特徴とする請求の範囲第[5] The pigment having a specific gravity of 2.0 or more is an inorganic white pigment.
4項に記載の画像形成方法。 Item 5. The image forming method according to Item 4.
[6] 前記比重が 2. 0以上の顔料を含有したインク力 25°Cで粘度が 7〜100mPa ' sであ ることを特徴とする請求の範囲第 4項に記載の画像形成方法。 6. The image forming method according to claim 4, wherein the viscosity is 7 to 100 mPa's at an ink force of 25 ° C containing a pigment having a specific gravity of 2.0 or more.
PCT/JP2005/023118 2005-01-12 2005-12-16 Ink jet head and image forming method WO2006075477A1 (en)

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