JP2007000832A - Liquid ejection method and liquid ejection apparatus - Google Patents

Abstract

Disclosed is a droplet discharge method capable of quantitatively and stably discharging a highly viscous liquid, which has been impossible in the past, and capable of discharging with good controllability from minute discharge to large volume discharge.
When discharging a droplet, the droplet holding surface is opened at the same time as the droplet leaves the droplet holding surface. Further, the droplet holding surface is a cylindrical nozzle, and at the same time the droplet is separated from the cylindrical nozzle, the cylindrical nozzle is divided and opened. If the liquid droplets before being discharged are held in the cylindrical nozzle, it is possible to attach importance to the quantitativeness of the liquid volume as in the case of the conventional inkjet nozzle. That is, a desired liquid volume to be ejected can be designed in advance from the nozzle diameter and height.
[Selection] Figure 1

Description

  The present invention relates to a method and a discharge device for discharging a small amount of a liquid such as a reagent or a chemical solution. The present invention also relates to a fine liquid pattern coating technique in the industrial liquid coating field.

  In recent years, as a method for forming a fine pattern film of a functional material, there is an increasing number of cases where an ink jet technique capable of directly pattern-applying a solution or dispersion of the film material is used.

  However, in the conventional inkjet technology, a liquid tank, a liquid flow path, and a discharge nozzle are connected, and the liquid flows continuously through the connected passage and is discharged from the discharge port. In other words, the ejected droplets were ejected by ejecting each droplet at the same time as the liquid column ejected from the ejection port was torn off in a natural or spontaneous manner. For this reason, since it is difficult for the liquid droplets to be separated from the discharge port, the viscosity of the liquid that can be discharged must always be low, and normally there is an upper limit of about 15 mPa · s, and a higher viscosity liquid is discharged. It was impossible to do. This phenomenon has been a big problem for the need to apply a fine pattern of a liquid made of a functional material as an industrial inkjet technique.

  In addition, since the liquid discharge port has a cylindrical shape, when the liquid near the discharge port is dried, solids contained in the liquid remain in and around the discharge port, and the discharge port is easily clogged. It was. Furthermore, since the clogged discharge port has a small diameter, physical cleaning such as brush cleaning is difficult. Therefore, the clogged inkjet head has to be discarded.

  In order to solve the above-described problem, there has been a technique for ejecting droplets using the inertial force by moving the entire cylindrical discharge port forward and backward in the discharge direction.

  That is, in Patent Document 1, an example in which the discharge port is configured to have an opening facing the external atmosphere and a minute hole having a smaller cross-sectional area than the opening, and the liquid holding member is moved forward and backward along the discharge direction. was there. According to this technology, there is an advantage that the discharge port is not easily clogged because the diameter facing the atmosphere is large.

Further, in Patent Document 2, in addition to the conventional ink jet method using piezo drive, there has been a proposal to increase the discharge volume by using the inertial force by moving the entire discharge port forward and backward.
JP 2002-116205 A JP-A-8-309976

  However, in Patent Document 1, once clogging occurs, cleaning is difficult because the discharge port has a cylindrical shape. In addition, only the liquid tearing method using only the inertial force has a limit to the controllability of the viscosity of the liquid that can be discharged and the discharge amount.

  Further, in Patent Document 2, it was possible to increase the discharge amount somewhat as compared with the normal ink jet system by an auxiliary action of inertia force, but this range has a limit, and further increases. However, there was a problem that another ink jet head having a large discharge port shape had to be prepared.

  Further, when the liquid near the discharge port was dried, solids contained in the liquid remained in and around the discharge port, and the discharge port was easily clogged. Further, since the discharge port has a cylindrical shape, it is difficult to cleanly clean the clogged discharge port. Also, since this method is a liquid tearing method, there is a limit to the viscosity of the liquid that can be discharged.

  An object of the present invention is to provide a droplet discharge method capable of quantitatively and stably discharging a high-viscosity liquid, which has been impossible in the past, and enabling discharge with good controllability from minute discharge to large-volume discharge. There is.

  In order to achieve the above object, the invention described in claim 1 is characterized in that, when a droplet is ejected, the droplet holding surface is opened at the same time as the droplet leaves the droplet holding surface.

  In the above method, when a droplet is ejected, first, a part of the droplet is ejected from the droplet holding surface (ejection port) into a semicircular shape, and then the semicircular droplet head is first placed inside the ejection port. The liquid is pulled out into a cylindrical shape. At this time, as the center of gravity of the droplet moves away from the droplet holding surface, the liquid in the latter half of the droplet loses momentum to discharge, and tends to return to the droplet holding surface side by the action of the surface tension of the droplet holding surface material. However, by simultaneously opening the holding surface at the same time, the liquid holding surface (discharge port surface) can be moved away from the droplets, so that the force that the droplets are pulled to the discharge port side by surface tension can be eliminated. That is, the ejected droplets cannot be returned and almost all the droplet amount is ejected.

  The timing for opening the droplet holding surface is preferably a time period immediately after the leading edge of the droplet jumps out of the holding surface and before the droplet tail (droplet trailing edge) is torn off.

  The opening speed of the droplet holding surface is preferably larger than the speed at which the droplets pop out. This is because if the speed is slow, a force for returning the droplets in the lateral direction (holding surface side) may be generated by the action of the surface tension of the droplet holding surface material.

  Further, the distance for opening the droplet holding surface is preferably at least twice the initial holding surface distance (or nozzle diameter).

  The invention according to claim 2 is characterized in that the droplet holding surface is a cylindrical nozzle, and the cylindrical nozzle is divided and opened at the same time when the droplet is separated from the cylindrical nozzle.

  If the liquid droplets before being discharged are held in the cylindrical nozzle, it is possible to place importance on the liquid volume quantification similar to the conventional ink jet nozzle. That is, a desired liquid volume to be ejected can be designed in advance from the nozzle diameter and height.

  According to the third aspect of the present invention, the droplet holding surface is composed of two or more close droplet holding surfaces, and at the same time the droplet held between the holding surfaces is separated from the droplet holding surface, the droplet holding surface is It is characterized by opening.

  In this case, since the portion corresponding to the peripheral length of the discharge port of the conventional inkjet nozzle is divided and shortened, the surface tension of the action of returning the liquid immediately after the discharge starts to the discharge surface side is Since it is originally small, it is characterized by being able to eject droplets with a smaller force.

  Since it can be divided as a part until it has a mechanism for opening the liquid holding surface, the liquid holding surface which is a discharge port can be disassembled and cleaned.

  In the invention according to claim 4, after the liquid is brought into contact with the tip of the droplet holding portion having two or more close droplet holding surfaces and the droplet is held between the holding surfaces by capillary action, the holding portion In the method of ejecting droplets with the inertial force of the droplets by moving the droplets forward in the droplet ejection direction and suddenly stopping or retreating the droplets, the droplets are separated from the droplet holding surface and held at the same time. It is characterized by opening the surface.

  In the above configuration, for example, when there are two liquid holding surfaces, the distance between the holding surfaces is set in advance to a distance range in which the liquid capillary phenomenon occurs. Next, when the tip of the droplet holder is brought into contact with the liquid, the droplet is held between the holding surfaces by capillary action. When the surface energy of the holding surface and the distance between the holding surfaces are determined, the appropriate amount of liquid to be held is naturally determined. Next, when the entire holding unit is advanced in the discharge direction and suddenly stopped or retreated, the held liquid jumps out from between the holding surfaces in the discharge direction and is discharged by the inertial force. Furthermore, by opening the liquid holding surface immediately after the ejection, the droplets fly off the holding surface more smoothly.

  The droplet discharge speed at this time increases as the forward movement speed at the tip of the liquid droplet holder increases and the forward distance increases to some extent. In addition, the discharge speed of the liquid droplets varies depending on the holding surface surface energy, the holding area, the opening speed of the holding surface, and the like. Therefore, in order to obtain an appropriate amount of liquid and a desired discharge speed, it is necessary to appropriately determine the advance speed, the advance distance, the holding surface surface energy, the holding area, the distance between the holding faces, and the opening speed of the holding face. For example, when the two holding surfaces are 30 × 30 μm and the distance between the holding surfaces is 30 μm, the appropriate amount of the holding liquid is about 27 pl. When the two holding surfaces are 10 × 10 μm and the distance between the holding surfaces is 10 μm, the appropriate amount of the holding liquid is about 1 pl.

  For example, if the liquid holding member is made of high-grade steel, the holding member can be disassembled for brush cleaning or ultrasonic cleaning when the tip is contaminated with liquid residue. It is. The material of the liquid holding member may be any material such as metal, plastic, ceramics, etc., but it is preferable that the liquid holding member has excellent workability to improve the shape accuracy of the tip and is chemically resistant to the liquid. . For example, stainless materials, engineering plastics, easily processable ceramics and the like can be mentioned.

  The invention described in claim 5 is characterized in that the liquid droplets are ejected in a liquid solvent atmosphere. If the above-described discharge operation is performed in a liquid solvent atmosphere, the liquid is difficult to dry, so that the amount of liquid does not change during the operation, and the discharge amount is stabilized. At the same time, liquid residue contamination of the holding member due to drying is eliminated.

  In order to make it specifically in the solvent atmosphere, for example, an enclosure that covers the entire ejection device is provided, and liquid vapor is sprayed therein. Alternatively, a means such as installing a liquid container having an open upper surface may be used.

  According to the sixth aspect of the present invention, it is possible to discharge a desired discharge droplet amount by setting the interval between the holding surfaces composed of two or more droplet holding portions to a desired interval by the adjusting mechanism. It is characterized by that.

  When the tip of the liquid holding part is composed of two, the liquid holding tip on one side is installed so as to be movable in the holding surface direction with a micrometer or the like. Next, the position of the holding surface may be determined while moving the micrometer while observing the holding surface with a microscope and measuring the distance between the holding surfaces with a microscope monitor.

  By this means, the volume of liquid entering by capillary action can be set freely. In other words, it is possible to control the discharge amount over a wide range with one discharge member. The invention according to claim 7 includes two or more droplet holders, an up-and-down driving means for driving the holding parts up and down, an opening and closing drive means for opening and closing the tip of the liquid holding part, a liquid tank, It consists of the connected liquid supply container.

  A holding member whose distance between the holding surfaces is set in advance so as to hold a desired droplet amount is attached to the vertical driving means, and is lowered by the driving means, so that the liquid surface filled in the liquid supply container connected to the liquid tank Make contact. After a certain time, after the liquid is held at the tip of the liquid holding unit, the holding member is then raised. Next, the holding member is moved horizontally to the substrate on which the droplet is to be landed. Next, the holding member is lowered at a high speed in the substrate direction, and the holding member is suddenly stopped in front of the substrate surface. The droplet is discharged from the holding member due to inertia. Immediately after the droplet jumps out of the holding member, that is, about several microseconds to several milliseconds after the sudden stop, the liquid holding unit tip is opened by the opening / closing driving means. The liquid droplets smoothly land on the substrate away from the front end of the holding unit.

  According to the first aspect of the present invention, even a highly viscous liquid that has been impossible in the past can be quantitatively and stably discharged with a slight force. In addition, it is possible to perform discharge with good controllability from minute discharge to large volume discharge. Furthermore, since the discharge port is easy to disassemble and clean, it is always clean and stable discharge with a long life is possible.

  According to the invention described in claim 2, in addition to the invention described in claim 1, it is possible to discharge liquid more quantitatively.

  According to the third aspect of the present invention, it is possible to perform liquid discharge with good liquidity and easier disassembly and cleaning of the discharge port. In addition, a liquid discharge mechanism with a simple structure is made possible.

  According to the fourth aspect of the present invention, the liquid can be discharged as a more specific process by the liquid supply method and the discharge operation method.

  According to the fifth aspect of the present invention, it is possible to prevent the liquid droplets from being dried during the discharge operation, thereby enabling more stable liquid discharge.

  According to the sixth aspect of the present invention, it is possible to discharge a wide range of droplet amounts from one discharge port.

  According to the seventh aspect of the invention, the liquid discharge can be performed automatically and continuously.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
A material for the liquid holding tip 1 as shown in FIG. 1A was prepared by leaving only the tip of one side of a 2 mm square stainless steel rod by a cutting method. Next, the tip part of the liquid holding tip part 1 of the present invention having a cross-sectional shape as shown in FIG. Individually produced.

  Separately, a driving and adjusting device is manufactured, and the two liquid holding tips 1 are attached to the driving and adjusting device with the liquid holding surface 2 facing each other, so that the distance between the liquid holding surfaces 2 is 50 μm. Was set accurately.

  The driving and adjusting device is provided with adjusting means 10 shown in FIG. 7 that can be adjusted by a micrometer mechanism for accurately adjusting the distance between the pair of liquid holding surfaces 2.

  Further, this driving and adjusting device opens and closes the liquid holding tip 1 shown in FIG. 5 for vertically moving the liquid holding tip 1 composed of a high-speed fine movement stage and the liquid holding tip 1 to which an electromagnetic on-off valve mechanism is applied. For this purpose, an opening / closing driving means 9 shown in FIG. 6 is provided. Furthermore, a control board and a computer for controlling each driving means are provided, and the vertical speed, the movement start position, the movement stop position, the opening / closing timing of the holding tip 1 are set in advance by them. Can be done.

  Liquid 3 is a silver paste / ink having a surface tension of 51 dyne / cm and a viscosity of 60 mPa · s consisting of 15 parts of alcohol-soluble silver colloid paste (manufactured by Nippon Paint), 2 parts of polyacrylic acid, 5 parts of ethylene glycol, and 35 parts of water. Prepared.

  Next, a petri dish having a diameter of 50 mm was prepared as the liquid supply container 4 shown in FIG. 1A, and the liquid 3 was filled in the petri dish. A liquid holding tip 1 was placed above the petri dish. Next, the liquid holding tip 1 was slightly brought into contact with the liquid 3 as shown in FIG. At this time, the liquid 3 entered between the liquid holding surfaces 2 by capillary action. Immediately as shown in FIG. 1C, the liquid holding tip 1 was pulled upward. At this time, it was confirmed that the holding liquid 5 entered between the liquid holding surfaces 2 as shown in the figure. Immediately, the liquid holding tip 1 was moved horizontally and moved onto a blue glass substrate having a thickness of 1.1 mm as the substrate 7 in FIG. Next, as shown in FIG. 1E, the liquid holding tip 1 is moved 5 mm downward at a speed of 300 mm / second by the up-and-down moving mechanism to make a sudden stop, and at the same time, the liquid holding tip 1 is not shown. The opening / closing drive means 9 opened the surface to a distance of 150 μm.

  The ejected droplets 6 were ejected by the inertial force, and were forcibly separated from the liquid holding tip 1 and landed on the surface of the substrate 7 as shown in FIG. A silver paste ink having a viscosity of 60 mPa · s was discharged well and landed on the substrate. At this time, the humidity of the environmental atmosphere was 55%, and it took about 5 seconds from liquid contact to landing.

  When the shape of the ejected droplet 6 was measured from a photograph by microscopic observation photography equipped with a high-speed shutter camera, the shape after ejection (after the droplet left the liquid holding surface) was 500 s in shape, and its diameter was spherical. By measuring the discharge amount (volume), it was confirmed that it was 120 pl (picoliter).

  When this liquid discharge operation was performed 20 times and the amount of each discharged liquid was measured, the variation was ± 10.3%.

<Embodiment 2>
The three liquid holding tip portions 1 of the first embodiment are manufactured, and the three liquid holding surfaces 2 as shown in FIG. Attached to. Furthermore, it was accurately set so that one side of an equilateral triangle composed of a line connecting the centers of the liquid holding surfaces 2 was 50 μm.

  Under the same conditions as in the first embodiment, the holding liquid 5 is held between the liquid holding surfaces 2 and is moved downward and suddenly stopped. At the same time, the liquid holding tip 1 is not shown in FIG. 2B. It was opened by the opening / closing drive means 9.

  When the discharge amount was converted by the same method as in the first embodiment, it was confirmed that the volume of the discharged droplet 6 was 175 pl (picoliter). When this liquid discharge operation was performed 20 times and the amount of each discharged liquid was measured, the variation was ± 9.1%.

  By increasing the holding surface, the accuracy of droplet quantification was improved.

<Embodiment 3>
A material for the liquid holding front end portion 1 as shown in FIG. 1A of Embodiment 1 was prepared, and nickel was electroplated on the front end portion to a thickness of about 100 μm. Further, the present invention comprises a holding surface 2 having a trapezoidal cross section as shown in FIG. 3 (a), a semicircular shape with an R of 20 .mu.m and a groove having a length direction of 50 .mu.m at the tip by a precision cutting method. Two liquid holding tips 1 were prepared.

  Two liquid holding tip portions 1 were produced, and attached to a mechanical fixing control mechanism (not shown) so that the liquid holding surface 2 was opposed. Further, the liquid holding surface 2 was brought into close contact as shown in FIG. 3A, and was set to have a cylindrical nozzle shape with a diameter of 40 μm and a length of 50 μm.

  In the same manner as in the first embodiment, the same liquid as in the first embodiment is held between the liquid holding surfaces 2 as shown in FIG. As shown in FIG. 3C, the liquid holding tip 1 was opened by an unshown opening / closing drive means 9 to perform droplet discharge.

  When the discharge amount was converted by the same method as in the first embodiment, it was confirmed that the volume of the discharged droplet 6 was 70 pl (picoliter). When this liquid discharge operation was performed 20 times and the amount of each discharged liquid was measured, the variation was ± 8.5%.

  Similar to the second embodiment, by making the holding surface cylindrical, the quantitative accuracy of the droplets was improved.

<Embodiment 4>
The side view shape of the shape of the liquid holding tip 1 is not limited to that shown in FIG. For example, if it is made into the shape of FIG.4 (b), it will be easy to process. If photolithographic processing is used instead of mechanical cutting, the shape becomes simple as shown in (b), and the liquid holding surface 2 can be accurately formed to about 5 to 20 μm. If this method is used, it is possible to discharge a small amount of fine liquid droplets of several pl.

  Further, the shape as shown in FIG. 4C makes it difficult for the retained liquid 5 to fall, which is convenient when a large amount of liquid is retained.

  4D, when the liquid holding tip 1 is slightly in contact with the liquid 3 in the process of FIG. 1B, only the holding surface is in contact with the liquid. There are few cases where excess liquid adheres to the bottom surface of the liquid holding tip 1. Liquid retention failure can be reduced.

  The cross-sectional shape of the shape of the liquid holding tip 1 is not limited to that shown in FIG.

  For example, if the shape shown in FIG. If photolithographic processing is used instead of mechanical cutting, the shape becomes simple as shown in (b), and the liquid holding surface 2 can be accurately formed to about 5 to 20 μm.

  Further, if the shape is as shown in FIG. 4G, the liquid can easily enter the recess, and the quantitativeness of the retained liquid 5 is improved by the same effect as in FIG.

<Embodiment 5>
Exactly the same discharge operation as in the first embodiment was performed in an environment with a humidity of 95% by placing the apparatus of the first embodiment in a constant humidity container.

  When the shape of the discharge droplet 6 was measured by microscopic photography equipped with a high-speed shutter camera, the shape after 500 μsec after discharge was spherical, and when the discharge amount was converted by measuring its diameter, the discharge droplet was The volume of 6 was confirmed to be 128 pl (picoliter).

  When this liquid discharge operation was performed 20 times and the amount of each discharged liquid was measured, the variation was ± 7.6%. By discharging in a constant humidity environment, drying of the retained liquid 5 can be prevented, and variations in the discharge amount can be reduced.

<Embodiment 6>
Two liquid holding tips 1 according to the first embodiment are prepared, and the distance between the liquid holding surfaces 2 can be adjusted by a micrometer as shown in FIG. Attached to the adjusting device. The distances between the liquid holding surfaces 2 are set to 90 μm, 70 μm, 50 μm, 30 μm, and 15 μm, respectively, as shown in FIGS. 5A and 5B, and then the same method as in the first embodiment at each distance. Then, droplet discharge was performed.

  When the respective discharge amounts were converted by the same method as in the first embodiment, the discharge droplet 6 had a volume of 222 pl when the distance between the holding surfaces was 90 μm, 166 pl when it was 70 μm, 120 pl when it was 50 μm, It was confirmed that it was 75 pl at 30 μm and 40 pl at 15 μm. By this method, it was possible to change the discharge amount from 40 to 222 pl with one liquid discharge head.

<Embodiment 7>
The liquid holding tip 1 of the first embodiment is manufactured, and the driving and adjusting device provided with the vertical driving means 8 and the opening / closing means 9 with the liquid holding surface 2 facing each other is shown in FIG. It was attached as follows.

  A silver paste ink similar to that of the first embodiment was prepared and injected into the liquid tank 11. The silver ink, which is a liquid, always flows from the liquid tank 11 through the liquid supply path 12 to the liquid supply container 4 having a liquid amount adjusting mechanism (not shown). Further, as shown in FIG. 8A, a partition wall 13 is provided around the apparatus, and the atmosphere in the partition wall is set to an atmosphere of solvent vapor by the volatilization of the liquid solvent from the liquid supply container 4.

  A glass substrate 7 was placed on a moving stage (not shown) in an open portion on the lower surface of the apparatus. Next, the liquid holding tip 1 is brought into contact with the liquid in the liquid supply container from the position of FIG. 8A, the liquid holding surface 2 holds the liquid, and the liquid holding tip 1 is immediately raised. It was moved horizontally to the position 8 (b). Next, the liquid holding front end 1 was moved downward by 3 mm at a speed of 200 mm / second to open the liquid holding surface 2 simultaneously with a sudden stop. As shown in FIG. 8C, the ejected droplet 6 was ejected by the inertial force and landed on the surface of the substrate 7. Next, the liquid holding tip 1 was returned to the position shown in FIG. 8A, and one cycle was completed in about 3 seconds.

  Continuous liquid discharge was possible by repeatedly performing the liquid discharge in one cycle while moving the substrate on the moving stage. Further, it was possible to discharge liquid even with a silver paste ink having a viscosity of 60 mPa · s, which was impossible with the conventional ink jet.

It is a figure which shows one example of the liquid discharge method of this invention. It is a figure which shows another example of a shape of the liquid holding | maintenance front-end | tip part of the liquid discharge method of this invention. It is a figure which shows another example of a shape of the liquid holding | maintenance front-end | tip part of the liquid discharge method of this invention. It is a figure which shows another example of a shape of the liquid holding | maintenance front-end | tip part of the liquid discharge method of this invention. It is a figure which shows the vertical drive means of the liquid holding front-end | tip of the liquid discharge method of this invention. It is a figure which shows the opening / closing drive means of the liquid holding front-end | tip of the liquid discharge method of this invention. It is a figure which shows the example of the adjustment method between the liquid holding tips of the liquid discharge method of this invention. It is a figure which shows one example of the liquid discharge apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid holding | maintenance front-end | tip part 2 Liquid holding surface 3 Liquid 4 Liquid supply container 5 Holding liquid 6 Discharge droplet 7 Substrate 8 Vertical drive means 9 Opening / closing drive means 10 Control means 11 Liquid tank 12 Liquid supply path 13 Partition

Claims (7)

  A droplet discharge method, wherein when a droplet is discharged, the droplet holding surface opens at the same time as the droplet leaves the droplet holding surface.   The droplet discharge method according to claim 1, wherein the droplet holding surface is a cylindrical nozzle, and at the same time the droplet is separated from the cylindrical nozzle, the cylindrical nozzle is divided and opened.   The droplet holding surface is composed of two or more close droplet holding surfaces, and the droplet held between the holding surfaces opens the droplet holding surface at the same time as it leaves the droplet holding surface. Item 2. A droplet discharge method according to Item 1.   A liquid is brought into contact with the tip of a droplet holding portion having two or more close droplet holding surfaces, and after holding a droplet between the holding surfaces by capillary action, the holding portion is advanced in the droplet discharge direction, A method for ejecting a liquid droplet by applying an inertial force to the liquid droplet by abruptly stopping or retreating, wherein the liquid droplet is separated from the liquid droplet holding surface and simultaneously the liquid droplet holding surface is opened. Item 2. A droplet discharge method according to Item 1.   The droplet discharge method according to claim 1, wherein the droplet is discharged in a liquid solvent atmosphere.   2. A desired discharge droplet amount can be discharged by setting an interval between the holding surfaces including two or more droplet holding portions to a desired interval by an adjusting mechanism. Droplet discharge method.   It comprises two or more droplet holders, a vertical drive means for driving the holder up and down, an open / close drive means for opening and closing the tip of the liquid holder, a liquid tank, and a liquid supply container connected to the liquid tank. A liquid discharge apparatus characterized by that.

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