JP5314854B2 - Evaluation method of piezoelectric element - Google Patents

Description

  The present invention relates to an ink jet recording system having excellent ink filling properties and a recording apparatus using the same.

In recent years, ink jet recording technology has advanced remarkably, and it has become possible to obtain high-definition and extremely similar images. As a result, ink jet recording has been used in many fields. Accordingly, in addition to obtaining high-definition images, it has been desired to improve the printing speed. In order to improve the printing speed, there is a method of increasing the number of nozzles and ejecting more ink droplets per unit time of one head. In this method, a drive frequency of 15 kHz or more is desired, and the ink used per unit time of one head must be supplied from the ink cartridge without excess or deficiency.
However, in an ink jet head, if the wettability of the ink flow path provided in the head is poor, there is a risk that bubbles are generated in the ink flow path when the ink is filled. Further, the bubbles are firmly attached to the wall surface of the flow path, and cannot be easily discharged even if a discharging operation by ink suction is performed. If air bubbles remain in the ink flow path, specifically, there are problems such as inability to eject, troubles such as missing dots and disordered printing, and deterioration of printing quality.

  In order to solve the above problems, conventionally, a filler that has been imparted hydrophilicity by acid treatment or plasma treatment or has been imparted hydrophilicity by acid treatment in order to improve the wettability of a head component using a resin material. There have been proposed a method of containing selenium (see, for example, Patent Document 1). On the other hand, in order to increase the toughness strength of the piezoelectric element, a method has been proposed in which each layer is baked and formed in a laminated piezoelectric element (see, for example, Patent Document 2). However, in a configuration in which the ink and the piezoelectric element are in direct contact as shown in Patent Document 1, the hydrophilic treatment causes the piezoelectric element to corrode and deteriorate. Further, since the piezoelectric element disclosed in Patent Document 2 is a fired member such as ceramic, the surface has a fine uneven structure and is not easily filled with ink. If ink is not filled on the surface of the piezoelectric element that generates pressure and air bubbles remain, the generated pressure is not sufficiently transmitted to the ink, causing the ink to bend, cause the ejection speed to decrease, or cause ejection failure such as non-ejection.

Japanese Patent No. 3454514 JP 2004-114308 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording system that improves ink filling and has high reliability in an ink jet recording system including an ink jet recording head in which a part of a pressure chamber wall surface is composed of a piezoelectric element. It is in.

  As a result of intensive studies to solve the above problems, the present inventor has found that the average inclination of the surface of the piezoelectric element and the surfactant concentration in the ink are within a predetermined range, and the average inclination of the piezoelectric element and the interface in the ink The relational expression with the concentration of the activator is within a predetermined range, so that the speed of filling the ink jet recording head with ink is improved, and a highly reliable ink jet recording system that does not cause defective ejection nozzles can be realized. As a result, the present invention has been completed.

（２）前記インクジェット記録ヘッドは、複数のドット形成部からなり、該ドット形成部は前記加圧室とそれに連通する前記ノズルを有し、前記加圧室は基板と内部に共通電極が形成された前記圧電素子とから構成されており、前記圧電素子に駆動電圧を印加するための個別電極が前記圧電素子の前記加圧室に対向する位置に配設されていることを特徴とする前記（１）に記載のインクジェット記録システム。
（３）前記インクは、少なくとも、水、着色剤、水溶性有機溶剤および界面活性剤からなることを特徴とする前記（１）に記載のインクジェット記録システム。
（４）前記着色剤は、顔料からなることを特徴とする前記（３）に記載のインクジェット記録システム。
（５）前記（１）〜（４）のいずれかに記載のインクジェット記録ヘッドはノズルを５００個以上有し、前記記録ヘッドを記録媒体の搬送方向に対して直交する水平方向に２個以上配置してなるインクジェット記録システムを用いたことを特徴とする記録装置。 That is, the inkjet recording system of the present invention and the recording apparatus using the same have the following configuration.
(1) A part of the wall surface of the pressurizing chamber provided with the nozzle is formed of a piezoelectric element, and the piezoelectric element is actuated and deformed to cause a pressure wave to act on the ink in the pressurizing chamber. An ink jet recording system including an ink jet recording head for ejecting ink droplets from the surface, wherein the average inclination Δa of the surface of the piezoelectric element is 0.1 to 1.0 rad, and the ink contains a surfactant, An ink jet recording system, wherein the activator concentration C is in the range of 0.01 to 1.0 times the critical micelle concentration CMC in the vehicle and satisfies the following formula (1).

(2) The ink jet recording head includes a plurality of dot forming sections, and the dot forming section includes the pressurizing chamber and the nozzle communicating with the pressurizing chamber, and the pressurizing chamber has a common electrode formed inside the substrate. The piezoelectric element, and an individual electrode for applying a driving voltage to the piezoelectric element is disposed at a position facing the pressurizing chamber of the piezoelectric element. An ink jet recording system according to 1).
(3) The ink jet recording system according to (1), wherein the ink includes at least water, a colorant, a water-soluble organic solvent, and a surfactant.
(4) The inkjet recording system according to (3), wherein the colorant is made of a pigment.
(5) The ink jet recording head according to any one of (1) to (4) has 500 or more nozzles, and two or more recording heads are arranged in a horizontal direction perpendicular to the conveyance direction of the recording medium. A recording apparatus using the ink jet recording system.

  According to the present invention, the average inclination Δa of the piezoelectric element surface and the surfactant concentration in the ink are in a predetermined range, and the relational expression between the average inclination Δa of the piezoelectric element surface and the surfactant concentration in the ink is predetermined. Therefore, it is possible to obtain a highly reliable ink jet recording head in which the ink jet recording head is quickly filled with ink and does not cause defective ejection nozzles.

The ink jet recording system according to the present invention will be described in detail below.
In the ink jet recording system of the present invention, a part of the wall surface of the pressurizing chamber provided with the nozzle is formed of a piezoelectric element, and this piezoelectric element is actuated and deformed to apply a pressure wave to the ink in the pressurizing chamber. An ink jet recording system comprising an ink jet recording head for ejecting ink droplets from the nozzle, wherein the average inclination Δa of the surface of the piezoelectric element is 0.1 to 1.0 rad, and the ink is a surfactant. The concentration of the surfactant is in the range of 0.01 to 1.0 times the critical micelle concentration in the vehicle, and further satisfies the above formula (1).

  According to the present invention, it has been found that the ink filling property of the ink jet recording head is related to the average inclination of the surface of the piezoelectric element that directly contacts the ink and generates the pressure wave. That is, when the average inclination Δa of the surface of the piezoelectric element is smaller than 0.1 rad, a sufficient amount of strain cannot be obtained even when a voltage is applied to the piezoelectric element, and the original function as a piezoelectric element cannot be achieved. . On the other hand, when the average inclination Δa is larger than 1.0 rad, the time required for the ink to reach a desired filling rate becomes longer and the filling rate decreases. This is considered that when the average inclination Δa is large, it takes time for the ink to enter the fine deep structure. Further, it is presumed that the ink cannot enter the fine deep structure on the surface of the piezoelectric element, and air remains as fine bubbles on the surface of the piezoelectric element, so that the filling rate is lowered. Within the scope of the present invention, the time required to reach the desired filling rate is shortened, and the filling rate is improved. Here, the filling rate refers to the ratio of the number of nozzles capable of printing to the total number of nozzles of the ink jet recording head.

  It was also found that the ink filling property is related to the surfactant concentration in the ink. That is, when the concentration of the surfactant is less than 0.01 times the critical micelle concentration (CMC), the wettability with respect to the surface of the piezoelectric element decreases, and the filling rate decreases. Further, when the concentration of the surfactant exceeds CMC, nozzle clogging or the like occurs, which causes a practical problem. This is presumably because when the concentration of the surfactant exceeds CMC, the micelles themselves become large and the abundance thereof increases. Here, the critical micelle concentration is the concentration of the surfactant at the time when a cloud point is generated when the surfactant is added to the vehicle excluding the color material at 25 ° C.

  In addition, the filling rate of the ink is rapidly increased when the average inclination Δa of the surface of the piezoelectric element and the concentration of the surfactant satisfy the above formula (1). If it is out of the range of the above formula (1), it takes time to increase the filling rate. This is because Δa is related to the area where the ink gets wet, and the surfactant concentration is related to the wettability of the ink with respect to the surface of the piezoelectric element. It can be said.

(ink)
The ink in the present invention comprises at least water, a colorant, a water-soluble organic solvent, and a surfactant, and in addition, a pH adjuster, an antiseptic and fungicide can be added as necessary.

As the colorant, any of direct dyes, acid dyes, basic dyes and other dyes and pigments can be used. In the present invention, a pigment is preferably used from the viewpoints of high optical density, water resistance, light resistance and the like.
As pigment components, colorant pigment components such as insoluble azo pigments, soluble azo pigments, phthalocyanine blue, isoindolinone, quinacridone, dioxazine violet, organic pigments such as verinone / betalin, and inorganic pigments such as carbon black and titanium dioxide And extender pigments such as white clay, talc, clay, diatomaceous earth, calcium carbonate, barium sulfate, titanium oxide, alumina white, silica, kaolin, and aluminum hydroxide.
Specific organic pigments are exemplified below. Examples of magenta pigments include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment Red 16, CI Pigment Red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.
As content with respect to the whole liquid medium of a pigment, 1-10 wt (mass)% is preferable, More preferably, it is 3-7 wt%.

In addition, a water-soluble resin is used to disperse the pigment in the ink solvent, and preferably a styrene-acrylic-acrylic acid alkyl ester copolymer, a styrene-acrylic acid copolymer, a styrene-maleic acid copolymer, a styrene- Maleic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-alkyl methacrylate ester copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene -A water-soluble resin such as a maleic acid copolymer.
As content with respect to the whole liquid medium of water-soluble resin, 0.1-10 wt% is preferable, More preferably, it is 1-5 wt%. Two or more of these water-soluble resins can be used in combination.

As a method for dispersing the pigment, a ball mill, a sand mill, a roll mill, an agitator, an ultrasonic homogenizer, a wet jet mill, a paint shaker, or the like can be used.
The pigment dispersion of the present invention is preferably subjected to filtration using a centrifugal separator or a filter in order to remove foreign matters, dust, coarse particles and the like during dispersion.

  The average particle size of the pigment particles in the present invention is preferably 30 to 300 nm, more preferably 50 to 150 nm. The average particle size can be measured using, for example, a dynamic light scattering type particle size distribution measuring device (LB-550, manufactured by HORIBA).

  Examples of the surfactant used in the ink in the present invention include nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene / polyoxypropylene block copolymers. Is preferably used.

  The water-soluble organic solvent in the present invention is ethylene glycol monobutyl ether, triethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monomethyl ether, triethylene glycol, hexylene glycol, octanediol, thiodiglycol, 2-butyl-2- Ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-methyl-1,3-propanediol, 2,4-pentanediol, 1,5-pentanediol, 2 , 2-dimethyl-1,3-propanediol trimethylolpropane, 2-methyl-1,3-propanediol, diethylene glycol, propylene glycol, butanediol, ethylene glycol, glycerin, 2-pyrrole Don and the like.

(Inkjet recording head)
In an example of the ink jet recording head of the present invention, FIG. 1 shows a state before a piezoelectric actuator including a laminated piezoelectric element 8 and individual electrodes 9 is attached.
The ink jet recording head 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 cross-sectional view showing one dot forming portion in a state where the piezoelectric actuator is attached in the ink jet recording head of the above example, and FIG. 2B is a diagram showing one dot forming portion. It is a perspective view which shows the overlapping state of each part which comprises. 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 600 dpi is realized as a whole of the ink jet recording head.
Each dot forming portion is formed on the upper surface side of the substrate 1 in FIG. 2A and has a center at the center in the width direction of the rectangular portion, the diameter is equal to the width length, and the horizontal sectional shape is semicircular. The pressurizing chamber 2 having a flat plate shape with the end portions being at both ends in the longitudinal direction of the rectangular portion, and the semicircle and center of the end portion on the one end side of the pressurizing chamber 2 on the lower surface side of the substrate 1 Are connected to each other through a cylindrical nozzle passage 4 having the same diameter and the same center as the semicircle of the end portion, and the end on the other end side of the pressurizing chamber 2. The pressure chamber 2 is formed in the substrate 1 so as to communicate with each dot forming portion via a cylindrical supply port 5 having the same center as the semicircle of the portion (see FIG. 1). (Shown by a broken line).

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, the laminated piezoelectric element 8 having a planar shape and a transverse vibration mode having a common electrode 7 having the same size as that of the substrate 1, and the addition of each dot forming portion. The piezoelectric actuator AC is configured by laminating individual electrodes 9 having the same plane shape, which are substantially rectangular and are individually provided at positions overlapping the central portion of the pressure chamber 2 in this order.

  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 planar shape, and formed through drying, pre-baking, and firing steps, or a reactive sputtering method, It 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 vacuum deposition method or a reactive ion plating method.

  The average inclination of the surface of the piezoelectric element 8 can be obtained by subjecting the surface to growth by promoting grain growth under firing conditions, mechanical polishing, etching, or the like. The average inclination of the surface of the piezoelectric element 8 can be measured by using, for example, an optical interference type surface roughness measuring device (Wyko NT1100 manufactured by Veeco) to obtain the average inclination Δa.

  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 other surface 1e except the region A1, and the surface of the fourth substrate 1d is exposed without forming the water repellent layer 12 in the region A1. Thus, 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 ink jet recording head of the present invention draws the ink meniscus in the nozzle by deforming the piezoelectric element 8 in the direction of expanding the capacity of the pressurizing chamber 2 immediately before the dot formation, and then reduces the capacity of the pressurizing chamber 2. By deforming the piezoelectric element 8 in the direction of reduction, the piezoelectric element 8 is deformed in the direction of reducing the capacity of the pressurizing chamber 2 when the ink droplet is separated from the ink meniscus and ejected, and at the time of dot formation. Thus, the ink meniscus in the nozzle 3 is pushed out, and then the piezoelectric element is deformed in the direction of expanding the capacity of the pressurizing chamber 2, thereby drawing the ink meniscus and separating the ink droplets from the ink meniscus and ejecting them. It may be driven by any driving method of the push type.

In the recording apparatus of the present invention, in order to achieve high-speed printing, the recording head has 500 or more nozzles, preferably 1000 to 3000 nozzles, the driving frequency is 15 kHz or more, and the recording head performs recording. Two or more, preferably 2-8, more preferably 2-4, may be connected in the horizontal direction perpendicular to the medium transport direction. Moreover, it can be used as a line head by connecting a plurality more than the width of the recording medium.
In the initial filling of the ink into the ink jet recording head, as shown in FIG. 1, the ink is pumped (not shown) between a pipe from an ink cartridge (not shown) and a joint portion 11 for connecting the pipe. The recording head is supplied through the joint portion 11. The pump can be used according to the purpose, such as a tube pump, a gear pump, or an electromagnetic pump.

  In the case of color printing, the ink is combined with the recording head to form a multi-color set, and normally an ink set including four colors of yellow, magenta, cyan, and black is formed. It is preferable that the recording apparatus is a combination of the ink and the recording head.

  Hereinafter, the ink jet recording system and the recording apparatus of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited only to the following examples.

(Production of vehicle)
The vehicle according to the present invention was prepared according to the following formulation.
Glycerin 10% by mass
2-Pyrodrine 5% by mass
85% by weight of water
The ethylene oxide adduct of 2-ethyl-2-butyl-1,3-propanediol represented by the following formula was added as a surfactant to the obtained vehicle, and the cloud point was determined to be 1.50. When it reached mass%, a cloud point was shown. That is, the critical micelle concentration of the vehicle was 1.50% by mass.

(Preparation of ink)
The ink according to the present invention is ink no. A to E were prepared according to the formulation shown in Table 1. The manufacturing method is as follows. Each material shown in Table 1 was put into a beaker so that the total amount was 200 g, stirred with a stirrer at 800 rpm for 30 minutes, and then filtered with a 10 μm membrane filter. As the surfactant, an ethylene oxide adduct of 2-ethyl-2-butyl-1,3-propanediol was used.

(Preparation of inkjet recording head)
1 and 2 (a) and 2 (b). The dimensions are as follows: the area of the pressurizing chamber 2 is 0.2 mm ² , the width is 2200 μm, the depth is 100 μm, and the nozzle channel 4 The diameter 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, and the shapes of the ink discharge side opening 30 and the pressure chamber 2 side opening 31 are radii. An ink jet recording head having a circular shape of 10 μm and 20 μm, and 166 dot forming portions composed of these portions per row and 664 dot forming portions in total (4 rows) arranged on the substrate 1 is provided. Using.
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.
The average inclination of the surface of the used piezoelectric element, the surfactant concentration (C / CMC) with respect to the critical micelle concentration in the ink and vehicle were as shown in Table 2.

(Evaluation method)
Using the ink and the inkjet recording head obtained above, and a recording apparatus equipped with these, ink droplets were ejected after ink filling, and the ejection state was examined. Evaluation was performed as follows. That is, the ink Nos. Any one of A to E is pressure-filled at a pressure of 200 kPa using a gear pump from an ink tank into an ink jet recording head in which any piezoelectric element having an average inclination Δa shown in Table 2 is incorporated, and 25 ° C., 50%. Under an RH environment, the ink was discharged at a driving voltage of 20 V and a driving frequency of 15 kHz, and ink was ejected 5 seconds later to evaluate the filling rate. The filling rate was defined as the ratio of the number of nozzles that could be printed out of 664 nozzles.
As the evaluation criteria, a sample having a filling rate of 1 (100%) after 5 seconds was considered good.

  The average inclination Δa of the surface of the piezoelectric element in this example was measured using an optical interference type surface roughness measuring device (Wyko NT1100 manufactured by Veeco).

(Evaluation results)
As shown in Table 2, when the concentration ratio of the surfactant to the critical micelle concentration (C / CMC) is outside the range of the present invention, the filling rate is as low as 0.81 to 0.90 (Comparative Example 1, 2). Even when the concentration ratio of the surfactant to the average gradient and the critical micelle concentration is within the range of the present invention, when the value of the above formula (1) is outside the range of the present invention, the filling rate is as low as 0.94 (comparison) Example 3). Moreover, when the average inclination was outside the range of the present invention, the filling rate was as low as 0.86 (Comparative Example 4).
On the other hand, when the average gradient, the ratio of the surfactant to the critical micelle concentration (C / CMC) and the above formula (1) are within the range of the present invention, the filling rate becomes 1.0 and good results are obtained. Shown (Examples 1-5).

1 is a plan view showing an embodiment of a piezoelectric ink jet recording head according to the present invention. (A) is a partially enlarged longitudinal sectional view of the piezoelectric ink jet recording 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 Ink 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 (4)

A part of the wall surface of the pressurizing chamber provided with the nozzle is formed of a piezoelectric element, and the piezoelectric element is operated and deformed to cause a pressure wave to act on the ink in the pressurizing chamber. An evaluation method of a piezoelectric element in an inkjet recording system including an inkjet recording head for discharging
The average slope Δa of the surface of the piezoelectric element is 0.1 to 1.0 rad, the ink contains a surfactant, and the surfactant concentration C is 0.01 to 1 of the critical micelle concentration CMC in the vehicle. when Ru der within 2.0 times,
Evaluation method of a piezoelectric element characterized by Assess the ink filling property possessed by the piezoelectric element by the following formula (1).

The ink jet recording head includes a plurality of dot forming portions, and the dot forming portion includes the pressurizing chamber and the nozzle communicating with the pressurizing chamber, and the pressurizing chamber includes the substrate and the piezoelectric having a common electrode formed therein. 2. The device according to claim 1, wherein an individual electrode for applying a driving voltage to the piezoelectric element is disposed at a position facing the pressurizing chamber of the piezoelectric element. Evaluation method of piezoelectric element . 2. The method for evaluating a piezoelectric element according to claim 1, wherein the ink comprises at least water, a colorant, a water-soluble organic solvent, and a surfactant. 4. The method for evaluating a piezoelectric element according to claim 3, wherein the colorant comprises a pigment.

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