JP2008023988A - Introducing liquid for ink-jet head, ink-jet head, and ink-jet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an introducing liquid for an ink-jet head and the ink-jet head capable of preventing defective discharge and ensuring discharge stability when ink is discharged by an ink-jet recording method by suppressing bubbles from remaining in an ink channel. <P>SOLUTION: The introducing liquid for the ink-jet head is an introducing liquid that fills the ink-jet head prior to introduction of the ink into the ink-jet head. The liquid has a surface tension that satisfies an expression (1): 6 mN/m<(surface tension in 10 msec of life)-(surface tension in 1,000 msec of life)<16 mN/m. The contact angle with respect to an ink channel member of the applied ink-jet head is 25 degrees or less. The ink-jet head of this invention is filled with the introducing liquid of this invention. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inkjet head introduction liquid used when an ink is introduced into an inkjet head in an inkjet recording method, an inkjet head using the same, and an inkjet recording apparatus.

  In the ink jet recording method, ink is ejected by an ink jet head to form ink droplets, and a part or all of these are adhered to a recording material such as paper to perform recording. In such an ink jet recording method, an ink that can perform stable ejection without causing clogging in the nozzle portion of the ink jet head or the ink flow path, and can record a sufficiently high density with a clear color tone is required.

  By the way, the ink jet head is roughly divided into a thermal method and a piezo method, and a continuous jet type recording apparatus includes an electrostatic type in which discharged ink droplets are controlled by an electric field. Specifically, in the thermal system, ink is instantaneously heated with a heater to generate bubbles, and ink droplets are ejected using the force at this time. In the piezo method, ink droplets are ejected by applying force to ink by vibrating a piezoelectric element. There are two methods for applying a force to ink with a piezo method: a method of applying a force to ink with a piezoelectric element that vibrates vertically, and a method of applying a force to ink with a piezoelectric element that flexibly vibrates. In these methods, piezoelectric elements are stacked. As a result, the force applied to the ink can be improved. Among such piezo methods, in order to achieve high density and mass productivity, it is better to use a piezoelectric element that flexibly vibrates, and it is better not to use lamination.

  In order to fully demonstrate the ink performance in the ink jet recording method, especially when using a piezo ink jet head, it is necessary to minimize the loss of pressure waves caused by vibration and to transmit the force efficiently to the nozzle part. It is important to create a completely ink-filled state without leaving bubbles in the inkjet head. If bubbles remain in the inkjet head, the ejection force is not sufficiently transmitted to the ink, causing problems such as non-ejection and jet bending, and the performance required for inkjet recording is not satisfied. Therefore, it can be said that the ink filling state of the ink jet head is an important factor that affects the performance of ink jet recording.

So far, as a method of filling ink without leaving bubbles in the inkjet head, the bubble height immediately after foaming by the Ross Miles method is 2 mm or less, the bubble height after 5 minutes is 0 mm, It has been proposed to fill an inkjet head with an introduction liquid containing a water-soluble organic solvent having a surfactant activity and a lower volatility than water (see Patent Document 1). ).
JP 2000-94707 A

  However, since the ink jet head is formed of members made of various materials, and there are steps and minute gaps at each member bonding portion, even when the introduction liquid described in Patent Document 1 is introduced, the ink flow is reduced. Bubbles may remain in the path, and as a result, it is difficult to completely remove the bubbles when filling with ink.

  Therefore, the main problem of the present invention is to suppress the remaining bubbles in the ink flow path, thereby preventing ejection defects and ensuring ejection stability when ejecting ink in the ink jet recording method. An ink jet head introduction liquid, an ink jet head, and an ink jet recording apparatus are provided.

In order to solve the above problems, the inventors of the present invention conducted intensive studies with the aim of improving the wettability of the introduced liquid before filling the inkjet head with the introduced liquid before introducing the ink into the inkjet head. As a result, in general, surface tension at a lifetime of 1000 msec or more measured by the Wilhelmi method or the like has been paid attention as a measure of wettability, but the difference between the surface tension at a lifetime of 10 msec and the surface tension at a lifetime of 1000 msec is specified It was found that the introduction liquid in the range effectively acts to suppress the residual bubbles in the ink flow path. That is, the surface tension when the surface life is short greatly affects the wettability in the ink flow path. If the difference between the surface tension at the lifetime of 10 msec and the surface tension at the lifetime of 1000 msec is within the range of the present application, the introduction of the introduction liquid is performed. Sometimes it can be introduced without introducing bubbles. Therefore, even if the ink is replaced, bubbles do not remain in the ink flow path, and thereafter it is possible to ensure ejection defects and ink ejection stability.
Furthermore, depending on the material of the ink flow path member of the ink jet head to be applied, it is also possible to use an introduction liquid having a contact angle with respect to the ink flow path member of 25 degrees or less to suppress the remaining bubbles in the ink flow path. I found it important to do. Then, the present invention has been completed by finding that the introduction solution having these requirements can solve the above-mentioned problems all at once.

を満足する表面張力を有し、適用するインクジェットヘッドのインク流路部材に対する接触角が２５度以下となる、ことを特徴とするインクジェットヘッド用導入液。
（２）水、界面活性剤および水溶性有機溶剤からなり、前記水溶性有機溶剤は、炭素数６〜８のジオール、および有機性値（ＯＶ）が１５０以上の多価アルコールアルキルエーテルから選ばれる少なくとも一種を含有する（１）に記載のインクジェットヘッド用導入液。
（３）前記水溶性有機溶剤は、その含有量が導入液全重量に対して、０．１〜３５重量％である、（２）に記載のインクジェットヘッド用導入液。
（４）前記インク流路部材が、エポキシ樹脂、ステンレス鋼、ニッケル合金、ポリイミド樹脂、ポリカーボネート樹脂、およびシリコーン樹脂からなる群より選ばれる少なくとも１種からなる（１）に記載のインクジェットヘッド用導入液。
（５）（１）〜（４）のいずれかに記載の導入液が充填されてなる、インクジェットヘッド。
（６）（１）〜（４）のいずれかに記載の導入液が充填されたインクジェットヘッドを備えてなることを特徴とするインクジェット記録装置。
（７）（１）〜（４）のいずれかに記載の導入液をインクジェットヘッドのインク流路内に充填する工程と、インク流路内に充填された前記導入液をインクと置換する工程とを含むインクジェットヘッドへのインク導入方法。
（８）（１）〜（４）のいずれかに記載の導入液をインクジェットヘッドのインク流路内に充填する工程と、インク流路内に充填された前記導入液をインクと置換する工程と、置換したインクをノズルから記録媒体の表面に吐出させる工程とを含むインクジェット記録方法。 That is, the present invention has the following configuration.
(1) An introduction liquid filled in the ink jet head prior to the introduction of the ink into the ink jet head, the following formula (1)

An ink-jet head introduction liquid characterized by having a surface tension satisfying the above conditions and having a contact angle of the ink-jet head applied to the ink flow path member of 25 degrees or less.
(2) It consists of water, a surfactant and a water-soluble organic solvent, and the water-soluble organic solvent is selected from diols having 6 to 8 carbon atoms and polyhydric alcohol alkyl ethers having an organic value (OV) of 150 or more. The introduction liquid for inkjet heads according to (1), containing at least one kind.
(3) The ink-jet head introduction liquid according to (2), wherein the content of the water-soluble organic solvent is 0.1 to 35% by weight with respect to the total weight of the introduction liquid.
(4) The ink-jet head introduction liquid according to (1), wherein the ink flow path member is at least one selected from the group consisting of epoxy resin, stainless steel, nickel alloy, polyimide resin, polycarbonate resin, and silicone resin. .
(5) An inkjet head filled with the introduction liquid according to any one of (1) to (4).
(6) An ink jet recording apparatus comprising an ink jet head filled with the introduction liquid according to any one of (1) to (4).
(7) A step of filling the introduction liquid according to any one of (1) to (4) into the ink flow path of the inkjet head, and a step of replacing the introduction liquid filled in the ink flow path with ink. A method for introducing ink into an inkjet head comprising:
(8) A step of filling the introduction liquid according to any one of (1) to (4) into the ink flow path of the ink jet head, and a step of replacing the introduction liquid filled in the ink flow path with ink. And a step of discharging the substituted ink from the nozzle onto the surface of the recording medium.

  ADVANTAGE OF THE INVENTION According to this invention, when discharging ink in an inkjet recording method, there exists an effect that a discharge defect can be prevented and discharge stability can be aimed at.

  The introduction liquid for an inkjet head of the present invention (hereinafter simply referred to as “introduction liquid of the present invention”) is an introduction liquid filled in the inkjet head prior to the introduction of the ink into the inkjet head. That is, the introduction liquid of the present invention fills the ink jet head before introducing the ink into the ink jet head, and then introduces the ink into the ink jet head to replace the introduction liquid with the ink. The ink can be filled without leaving bubbles. As a result, the ink can be ejected with good ejection stability without causing ejection defects.

  The method for replacing the introduction liquid of the present invention filled in the ink jet head with ink is not particularly limited. For example, in the state where the ink cartridge containing the ink is connected to the ink jet head, the ink jet head is disposed on the ejection port side. Adopting a method such as sucking ink with a pump with a cap, transporting ink using a pump, or extruding and transporting ink by pressurizing a cartridge or sub tank with air Can do.

  That is, the method for introducing ink into the ink jet head of the present invention includes filling the ink into the ink flow path of the ink jet head, and then substituting the ink introduced into the ink flow path with ink to form the ink jet head. This is a method of introducing ink.

を満足する表面張力を有することが重要である。好ましくは、下記式（２）

を満足する表面張力を有するのがよい。（寿命１０ｍｓｅｃにおける表面張力−寿命１０００ｍｓｅｃにおける表面張力）の値が１６ｍＮ／ｍ以上であると、充分な濡れ性が得られず、インク流路内の気泡を残留するのを抑制することができない。他方、インクジェットヘッドに充填される、水と水溶性有機溶剤とを含有してなる通常の導入液において、（寿命１０ｍｓｅｃにおける表面張力−寿命１０００ｍｓｅｃにおける表面張力）の値が６ｍＮ／ｍ以下である導入液を得ることは、界面活性剤等を入れた場合、有機溶剤の水への溶解性のため、実質的に困難である。 The introduction liquid of the present invention has the following formula (1):

It is important to have a surface tension that satisfies Preferably, the following formula (2)

The surface tension should satisfy If the value of (surface tension at a lifetime of 10 msec−surface tension at a lifetime of 1000 msec) is 16 mN / m or more, sufficient wettability cannot be obtained, and it is not possible to suppress the remaining bubbles in the ink flow path. On the other hand, in a normal introduction liquid containing water and a water-soluble organic solvent filled in the ink jet head, the value of (surface tension at a lifetime of 10 msec−surface tension at a lifetime of 1000 msec) is 6 mN / m or less. It is substantially difficult to obtain a liquid when a surfactant or the like is added due to the solubility of the organic solvent in water.

  In the present invention, the surface tension with respect to the surface lifetime, that is, the surface tension at a lifetime of 10 msec and the surface tension at a lifetime of 1000 msec are measured by a dynamic surface tension measurement method using a capillary as represented by the bubble pressure method. It is. Specifically, bubbles are generated in the liquid from the capillary, the surface tension is measured from the pressure applied to the bubbles, and the dynamic surface tension is measured by changing the bubble frequency (for example, 0.01 to 10 Hz). can do.

  It is important that the introduction liquid of the present invention has a contact angle of 25 degrees or less with respect to the ink flow path member of the applied inkjet head. Preferably, the contact angle with respect to the ink flow path member is 20 degrees or less. If the contact angle with respect to the ink flow path member exceeds 25 degrees, sufficient wettability cannot be obtained, and it is not possible to suppress the bubbles remaining in the ink flow path. When the ink jet head is composed of a plurality of ink flow path members made of different materials, it is important that the contact angles with respect to all the ink flow path members are within the above range. In such a case, the adhesive used to bond the members is also one of the ink flow path members.

  In the present invention, the contact angle with respect to the ink flow path member can be measured using a contact angle meter (for example, “CA-X type” manufactured by Kyowa Interface Science Co., Ltd.).

The introduction liquid of the present invention preferably contains water, a surfactant and a water-soluble organic solvent as essential components.
As water as an essential component, it is desirable to use deionized water (pure water). The water content is preferably 65 to 95% by weight based on the total weight of the introduced liquid.

  The surfactant that is an essential component includes a cationic surfactant, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, and the like. Among these, an anionic surfactant is particularly preferable. Or a nonionic surfactant is preferable. The content of the surfactant is preferably 0.1 to 5.0% by weight with respect to the total weight of the introduced liquid. In addition, only 1 type may be sufficient as surfactant, and 2 or more types may be sufficient as it.

  The water-soluble organic solvent which is an essential component is at least one of a diol having 6 to 8 carbon atoms or a polyhydric alcohol alkyl ether having an organic value (OV) of 150 or more (hereinafter sometimes referred to as “specific solvent component”). It is preferable to contain. The diol having 6 to 8 carbon atoms may have any hydroxyl group, and the hydroxyl group is effective in all combinations. Specific examples of the polyhydric alcohol alkyl ether having an organic value (OV) of 150 or more include diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monobutyl ether. The ratio of the specific solvent component with respect to the total weight of the introduced liquid is not particularly limited, but is preferably 0.1 to 35% by weight. Two or more types of the specific solvent component may be used. In this case, the ratio of the specific solvent component to the total weight of the introduced liquid is preferably 0.1 to 35% by weight. The water-soluble organic solvent may contain a solvent other than the specific solvent component. In that case, the content of the other solvent is within the above range. It is desirable to be within the range.

  The content of the water-soluble organic solvent that is an essential component is preferably 0.1 to 35% by weight, more preferably 0.5 to 25% by weight, based on the total weight of the introduced liquid. When the content of the water-soluble organic solvent is less than 0.1% by weight, it often becomes difficult to achieve a contact angle of 25 degrees or less with respect to the ink flow path member, while it exceeds 35% by weight. In addition, since the viscosity of the introduction liquid becomes high, it may be difficult to fill the introduction liquid itself.

  In addition to the essential components described above, the introduction liquid of the present invention may contain various additives such as a viscosity adjusting agent, a pH adjusting agent, an antiseptic and antifungal agent, as necessary, as long as the effects of the present invention are not impaired. It can be included. For colorants such as water-soluble dyes, foaming tends to be high when present in large amounts, so it is better not to contain them basically. It is possible to add a small amount for the purpose of obtaining properties.

  In the present invention, the ink flow path member is preferably made of at least one selected from the group consisting of epoxy resin, stainless steel (SUS), nickel alloy, polyimide resin, polycarbonate resin, and silicon resin. . If the ink flow path member is made of a material selected from the above group, and the introduced liquid has a surface tension in the above-described range, the contact angle between them is easily 25 degrees or less. Of course, the ink flow path member in the present invention is not limited to one selected from the above group.

  The ink jet head filled with the introduction liquid of the present invention is not particularly limited. However, if the ink jet head has 400 nozzles or more per one head, the effect of the present invention appears more remarkably. It is.

  The ink jet head of the present invention is preferably filled with the introduction liquid of the present invention described above. As described above, the introduction liquid fills the inkjet head before introducing the ink into the inkjet head. In filling the introduction liquid, as shown in FIG. 1, the introduction liquid is supplied to the inkjet head 21 via a pipe from an introduction liquid cartridge (not shown) and a joint portion 11 for connecting the pipe. A pump (not shown) is disposed between the cartridge and the joint portion 11 so that the introduced liquid can be transported. The pump can be used according to the purpose, such as a tube pump, a gear pump, or an electromagnetic pump.

  The inkjet head of the present invention filled with the introduction liquid has a cap on the discharge side (discharge nozzle hole and the like) and a valve and a plug on the ink entrance / exit so as to eliminate the place of communication with the atmosphere. Leakage and evaporation may be prevented. In addition, the ink jet head of the present invention can be transported independently by removing it from the ink cartridge or cap in a state where the introduction liquid is filled. It may be covered with a cover such as an adhesive tape or rubber to suppress leakage or evaporation of the introduced liquid.

  FIG. 1 shows an example of an ink jet head according to the present invention in a state before a piezoelectric actuator including a laminated piezoelectric element 8 and individual electrodes 9 is attached. The ink jet head 21 in the illustrated example has a plurality of dot forming portions including a pressurizing chamber 2 and a nozzle 3 communicating therewith arranged on a single substrate 1.

  2A is an enlarged partial cross-sectional view showing one dot forming portion in a state where the piezoelectric actuator AC is attached in the inkjet head 21 of the above example, and FIG. FIG. FIG. 3 is an enlarged view of the vicinity of the nozzle 3 in FIG. The nozzles 3 of the dot forming section are arranged in a plurality of rows in the main scanning direction (printing medium conveyance direction) indicated by white arrows in FIG. In the example shown in the figure, the lines are arranged in four rows, the pitch between the dot forming portions in the same row is 150 dpi, and the ink jet head 21 as a whole realizes 600 dpi.

  Each dot forming section includes a pressurizing chamber 2 having a flat plate shape formed on the upper surface side of the substrate 1, a nozzle 3 on the lower surface side of the substrate 1, and a nozzle channel 4 for communicating these. The pressurizing chamber 2 has ends at the center in the width direction of the rectangular portion, the diameter is equal to the width length, and the horizontal cross-sectional shape is semicircular at both ends in the longitudinal direction of the rectangular portion. ing. The pressurizing chamber 2 communicates with the common flow path 6 via a cylindrical supply port 5 having the same center as the semicircle of the end portion on the other end side of the pressurizing chamber 2. The nozzle 3 has a truncated cone shape with the same center as the semicircle of the end portion on the one end side of the pressurizing chamber 2. The nozzle channel 4 has a cylindrical shape having the same diameter and the same center as the semicircle of the end. The common flow path 6 is formed in the substrate 1 so as to communicate with each dot forming portion. The ink flow path described above includes at least the common flow path 6, the pressurizing chamber 2, and the nozzle flow path 4.

  In the example shown in the figure, each of the above parts includes a first substrate 1a in which the pressurizing chamber 2 is formed, a second substrate 1b in which an upper portion 4a of the nozzle channel 4 and a supply port 5 are formed, and a lower portion 4b of the nozzle channel 4. The third substrate 1c on which the common flow path 6 is formed and the fourth substrate 1d on which the nozzle 3 is formed as a nozzle plate are stacked and integrated in this order.

  In addition, as shown in FIG. 3, the nozzle 3 has an opening 30 at the tip on the ink droplet ejection side formed in a circle on the lower surface 1e of the fourth substrate 1d, which is the lower surface side of the substrate 1. At the same time, the nozzle 3 is formed in a tapered shape (conical shape) so that the opening 30 on the distal end side is smaller than the opening 31 on the pressurizing chamber 2 side.

  As shown in FIG. 1, the first substrate 1 a and the second substrate 1 b are connected to a common flow path 6 formed in the third substrate 1 c with piping from an ink cartridge (not shown) on the upper surface side of the substrate 1. The through-hole 11a for comprising the joint part 11 for doing is formed. Furthermore, each board | substrate 1a-1d consists of resin, a metal, etc., for example, and is formed with the plate-shaped body which has the through-hole used as said each part by the etching etc. which used the photolithographic method, and has predetermined thickness.

  On the upper surface side of the substrate 1, a piezoelectric actuator AC is configured by laminating a laminated piezoelectric element 8 having a planar shape and a transverse vibration mode, and individual electrodes 9 having the same substantially rectangular shape in this order. It is. The laminated piezoelectric element 8 is approximately the same size as the substrate 1 and has a common electrode 7 therein. The individual electrodes 9 are individually provided at positions overlapping the central portion of the pressurizing chamber 2 of each dot forming portion.

Both the common electrode 7 and the individual electrode 9 are formed of a metal foil excellent in conductivity such as gold, silver, platinum, copper, and aluminum, a plating film made of these metals, a vacuum deposition film, or the like.
As a piezoelectric material for forming the piezoelectric element 8, for example, lead zirconate titanate (PZT) or one or more oxides of lanthanum, barium, niobium, zinc, nickel, manganese, etc. are added to the PZT. Examples thereof include PZT-based piezoelectric materials such as PLZT. In addition, lead magnesium niobate (PMN), lead nickel niobate (PNN), lead zinc niobate, lead manganese niobate, lead antimony stannate, lead titanate, barium titanate, etc. You can also.

  The piezoelectric element 8 is formed by, for example, bonding and fixing a chip having a predetermined planar shape obtained by sintering a sintered body formed by sintering the above piezoelectric material into a thin plate shape at a predetermined position, or a so-called sol-gel method. (Or by the MOD method), a paste formed from an organometallic compound that is the basis of the piezoelectric material is printed in a predetermined plane shape, and is formed through drying, pre-baking, and baking processes. Alternatively, the piezoelectric material can be formed by forming a thin film of a piezoelectric material into a predetermined planar shape by a vapor phase growth method such as a reactive sputtering method, a reactive vacuum deposition method, or a reactive ion plating method.

  The surface roughness of the piezoelectric element 8 can be obtained by accelerating particle growth under firing conditions, surface processing using mechanical polishing, etching, or the like. The surface roughness of the piezoelectric element 8 is measured using, for example, an optical interference type surface roughness measuring device (Wyko NT1100 manufactured by Veeco) and can be evaluated as an average surface roughness Ra.

  In order to drive the piezoelectric element 8 in the transverse vibration mode, for example, the polarization direction of the piezoelectric material is oriented in the thickness direction of the piezoelectric element 8, more specifically in the direction from the individual electrode 9 to the common electrode 7. For this purpose, conventionally known polarization methods such as a high temperature polarization method, a room temperature polarization method, an alternating electric field superposition method, and an electric field cooling method can be employed. Moreover, you may age-treat the piezoelectric element 8 after polarization.

  The piezoelectric element 8 in which the polarization direction of the piezoelectric material is oriented in the above-described direction contracts in a plane orthogonal to the polarization direction by applying a positive drive voltage from the individual electrode 9 with the common electrode 7 grounded. To do. For this reason, the force when the bending occurs is transmitted to the ink in the pressurizing chamber 2 as a pressure wave, and the ink in the supply port 5, the pressurizing chamber 2, the nozzle flow path 4, and the nozzle 3 is transmitted by this pressure wave. Causes vibration. As a result of the vibration speed going outward from the nozzle 3, the ink meniscus in the nozzle 3 is pushed out from the opening 30 at the tip on the ink droplet ejection side to form an ink column. The vibration speed will eventually go in the nozzle, but the ink column will continue to move in the outward direction, so it will be separated from the ink meniscus and gathered into one or two ink drops that will fly in the direction of the paper. To form dots on the paper.

  The amount of ink that has decreased due to the flying ink droplets is reduced from the ink cartridge by the ink meniscus surface tension in the nozzle 3, the piping of the ink cartridge, the joint portion 11, the common flow path 6, the supply port 5, and the pressure chamber 2, and the nozzle 3 is refilled via the nozzle flow path 4.

  On the lower surface 1e of the fourth substrate 1d, which is the lower surface side of the substrate 1, as described above, an area A1 having a predetermined planar shape that is not subjected to water repellent treatment is provided at the tip of the nozzle 3 on the ink droplet ejection side. It is provided so as to overlap with the circular opening 30. That is, the water repellent layer 12 is laminated on the surface 1e other than the region A1 to perform water repellent treatment. In the region A1, the water repellent layer 12 is not formed, and the surface of the fourth substrate 1d is exposed, so that the water repellent treatment is not performed.

  Although the thickness of the water repellent layer 12 is not specifically limited, It is preferable that it is 0.5-2 micrometers. If the thickness of the water-repellent layer 12 is less than this range, the water repellency is lowered, and there is a possibility that ink droplet ejection failure due to ink adhesion may occur. Further, the water repellent layer 12 having a film thickness exceeding 2 μm is not easily formed, and even if it can be formed, there is a possibility that no further effect can be obtained.

  The inkjet head 21 of the present invention may be driven by either a driving method of a pulling type or a pressing type. In the pulling type, the ink meniscus in the nozzle is drawn by deforming the piezoelectric element 8 in the direction of expanding the capacity of the pressurizing chamber 2 immediately before the dot formation. Thereafter, the piezoelectric element 8 is deformed in the direction in which the capacity of the pressurizing chamber 2 is reduced, whereby ink droplets are separated from the ink meniscus and ejected. In the punching type, the ink meniscus in the nozzle 3 is pushed out by deforming the piezoelectric element 8 in the direction of reducing the capacity of the pressurizing chamber 2 at the time of dot formation. Next, by deforming the piezoelectric element in the direction of expanding the capacity of the pressurizing chamber 2, the ink meniscus is drawn, and the ink droplet is separated from the ink meniscus and ejected.

  In the ink jet recording apparatus of the present invention, in order to achieve high speed printing, the ink jet head 21 preferably has 600 nozzles or more, and the drive frequency thereof is 15 kHz or more. Two or more, preferably 2-8, more preferably 2-4, inkjet heads 21 may be arranged perpendicular to the recording medium conveyance direction and in the horizontal direction. In addition, by arranging a plurality of recording media that are larger than the width of the recording medium, it can also be used as a line head.

  In the ink jet recording method of the present invention, the introduction liquid is filled into the ink flow path 4 of the ink jet head 21, and then the introduction liquid filled in the ink flow path is replaced with ink. This is a recording method for discharging onto the surface of a recording medium.

  When performing color printing, the ink is combined with the inkjet head 21 to form a multicolor set, and usually an ink set including four colors of yellow, magenta, cyan, and black is formed. An ink jet recording apparatus in which ink and an ink jet head 21 are combined is preferable.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to a following example.
Each physical property of the introduced liquid was measured by the following method.

<Surface tension>
Using an automatic surface tension meter (“BP-D4” manufactured by Kyowa Interface Science Co., Ltd.), the surface tension is measured at 25 ° C. according to JIS K 3362, and the surface tension A at a lifetime of 10 msec and the surface tension B at a lifetime of 1000 msec are obtained. The difference (AB) was calculated.
<Contact angle>
Using a contact angle meter (“CA-X type” manufactured by Kyowa Interface Science Co., Ltd.), in a normal temperature (25 ° C.) environment, 5 μL of the introduced droplet to be measured is transferred from the syringe to the inner surface of the ink supply tube as a constituent member. Measured on the surface.

(Preparation of inkjet head)
The ink-jet head 21 is a system that applies a force to ink with a piezo that vibrates and vibrates, can be driven in a frequency range of 1 to 40 kHz, a drive voltage of 10 to 30 V, has 400 nozzles or more, and has an ink flow path. A member made of stainless steel (SUS) was used. The ink jet head 21 has the structure shown in FIGS. 1 and 2A and 2B, and the dimensions thereof are as follows: the area of the pressurizing chamber 2 is 0.2 mm ² , the width is 200 μm, and the depth is 100 μm. The diameter of the nozzle flow path 4 is 200 μm, the length is 800 μm, the diameter of the supply port 5 is 30 μm, the length is 40 μm, the length of the nozzle 3 is 30 μm, the ink discharge side opening 30 and the pressure chamber 2 side opening. The shape of 31 is a circle having a radius of 10 μm and 20 μm, respectively, and 166 dot forming portions composed of these portions are arranged on the substrate 1, and 664 dot forming portions in total (4 rows) are arranged on the substrate 1. The inkjet head 21 was used.
The pitch between the dot forming portions in the same row was 150 dpi, and the adjacent rows were shifted by ½ pitch to make 600 dpi as a whole.

(Examples 1-4 and Comparative Examples 1-5)
The components shown in Table 1 were sufficiently mixed and stirred, and then filtered through a 1.0 μm membrane filter to obtain an introduction solution. In addition, among each component shown in Table 1, “EO adduct of acetylenic diol” is an adduct obtained by adding 10 mol of ethylene oxide to acetylenic diol (“Surfinol 465” manufactured by Air Products). Moreover, among each component shown in Table 1, the organic value (OV) of ethylene glycol monobutyl ether is 120, and the organic value (OV) of triethylene glycol monobutyl ether is 200. Table 1 shows the physical properties of the obtained introduction liquids.
Next, the inkjet liquid 21 was filled with the obtained introduction liquid. Then, after being left for 1 month in an environment of 25 ° C. and 50% RH, an ink cartridge is mounted, the ink is transported by a pump, and the introduced liquid is replaced with ink (“ICC31” manufactured by Epson). Was evaluated. The results are shown in Table 1.

[Discharge stability (1)] When the nozzles are ejected continuously for 48 hours at a frequency of 20 kHz and a drive voltage of 20 V, the ink flying state is arbitrarily selected and photographed with a high-speed camera to print a line. This line was visually observed. The ejection stability was evaluated according to the following criteria.
A: The discharge speed is 8 m / s or more, and the line is not interrupted.
Δ: The discharge speed is 8 m / s or more, but the line is interrupted.
X: The discharge speed is less than 8 m / s.

[Discharge stability (2)] The ink droplet discharge state when 48 hours of continuous discharge was performed at a frequency of 20 kHz and a drive voltage of 20 V was arbitrarily selected from 50 nozzles and photographed with a high-speed camera for 1 hour. An ink landing accuracy check pattern was printed every time, and ejection stability was evaluated according to the following criteria.
A: The discharge speed is 8 m / s or more, and the landing accuracy is within ± 10 μm.
Δ: The discharge speed is 8 m / s or more, but the landing accuracy is worse than ± 10 μm.
X: The discharge speed is less than 8 m / s, and the landing accuracy is ± 10 μm or more.

[Discharge Defect] A nozzle check pattern was printed on glossy paper at a frequency of 20 kHz and a drive voltage of 20 V, and the discharge defect was evaluated according to the following criteria.
◯: There is no non-ejection nozzle, and the landing accuracy is within ± 10 μm.
Δ: There is no non-ejection nozzle, but the landing accuracy is worse than ± 10 μm.
X: There is a non-ejection nozzle.

  As shown in Table 1, Examples 1 to 4 in which the surface tension and the contact angle of the introduced liquid are within the range of the present invention have good discharge stability, no discharge nozzles were generated, and no discharge defects occurred. . On the other hand, Comparative Examples 1 to 5 in which the surface tension and the contact angle of the introduced liquid are outside the scope of the present invention have poor ejection stability or non-ejection nozzles.

It is a top view which shows embodiment of the inkjet head which concerns on this invention. (A) is a partially enlarged longitudinal sectional view of the inkjet head according to the present invention, and (b) is a bottom view of (a). It is an enlarged view of the nozzle part of Fig.2 (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Pressurization chamber 3 Nozzle 4 Nozzle flow path 5 Supply port 6 Common flow path 7 Common electrode 8 Piezoelectric element 9 Individual electrode 11 Joint part 12 Water repellent layer 30 Opening A1 area | region AC Piezoelectric actuator

Claims (8)

An introduction liquid filled in the ink jet head prior to the introduction of ink into the ink jet head, the following formula (1)

An ink-jet head introduction liquid characterized by having a surface tension satisfying the above conditions and having a contact angle of the ink-jet head applied to the ink flow path member of 25 degrees or less.   It consists of water, a surfactant and a water-soluble organic solvent, and the water-soluble organic solvent is at least one selected from diols having 6 to 8 carbon atoms and polyhydric alcohol alkyl ethers having an organic value (OV) of 150 or more. The ink-jet head introduction liquid according to claim 1, which is contained.   The ink-jet head introduction liquid according to claim 2, wherein the content of the water-soluble organic solvent is 0.1 to 35% by weight based on the total weight of the introduction liquid.   2. The liquid for introducing an ink jet head according to claim 1, wherein the ink flow path member is made of at least one selected from the group consisting of epoxy resin, stainless steel, nickel alloy, polyimide resin, polycarbonate resin, and silicone resin.   An ink jet head, which is filled with the introduction liquid according to claim 1.   An ink jet recording apparatus comprising an ink jet head filled with the introduction liquid according to claim 1.   To an inkjet head, comprising: a step of filling the introduction liquid according to claim 1 into an ink flow path of an inkjet head; and a step of replacing the introduction liquid filled in the ink flow path with ink. Ink introduction method.   A step of filling the introduction liquid according to any one of claims 1 to 4 into an ink flow path of an ink jet head, a step of replacing the introduction liquid filled in the ink flow path with ink, and a replacement ink And an ink jet recording method including a step of discharging the nozzle onto the surface of the recording medium.

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