JPS60209210A - Device for removing oxygen dissolved in ink - Google Patents

Abstract

PURPOSE:To remove dissolved oxygen in an ink by sudden change of pressure at the stage of ejection of the ink by ejecting the ink from a nozzle in the atmosphere of inactive gas. CONSTITUTION:When raw materials for ink are ejected by opening a valve V1 and opening simultaneously the valves V3 and V4, the materials are mixed and during mixing, the mixture is ejected from a nozzle 5 by the pressure of inactive gas from a gas source 9. After a specified amt. of the ink 2 is fed to an ink tank 1, the valves V3 and V4 are closed and the tank 2 in the ink tank is circulated and ejected from a nozzle 5. Simultaneously, the air in the ink tank 1 is discharged from the valve V1 by the inactive gas ejected from the nozzle 5 together with the ink 2. It is preferred that the pressure difference of the ink 2 before and after ejection from the nozzle 5 is >=0.1kg/cm<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ink dissolved oxygen removal device that removes dissolved oxygen contained in ink during ink production.

[Field of Application of the Invention] The present invention can be used, for example, to manufacture ink for writing instruments such as felt pens and fountain pens. It is useful when used in the production of water-based ink used in recording methods that perform recording by ejecting ink from an ejection orifice.

[Background of the invention and problems] Not only is it extremely difficult to isolate all processes from air during ink production, but the ink also contains dissolved oxygen because the ink raw materials already contain dissolved oxygen. This is an unavoidable situation.

However, when a large amount of dissolved oxygen is present in the ink, the dissolved oxygen oxidizes the components of the ink, resulting in the ink deteriorating in quality within a short period of time after production. This deterioration of ink does not simply cause changes in the color of the ink, but also especially in inkjet recording systems, which have extremely dense structures because minute amounts of ink are ejected at high speeds thousands of times per second. This can clog the recording head and cause it to malfunction.

Conventionally, in order to reduce the amount of dissolved oxygen in the ink that causes such problems as much as possible, ink that tends to increase dissolved oxygen is stirred and mixed in a nitrogen atmosphere. That is, in some cases, the stirring tank is a closed system, and the ink is stirred and mixed using a stirring device that can supply nitrogen gas to the inside. However, this ink stirring device only prevents the ink from coming into contact with air and increasing new dissolved oxygen when stirring and mixing the ink, but it also removes the dissolved oxygen originally contained in each ink raw material to be mixed. It's not possible. Therefore, if the existing amount of dissolved oxygen in each ink raw material is large, problems similar to those described above will occur.

[Object of the Invention] An object of the present invention is to make it possible to remove dissolved oxygen already dissolved in ink.

[Summary of the Invention] According to the present invention, dissolved oxygen in the ink can be removed by ejecting ink from a nozzle in an atmosphere of a non-reactive gas and by rapid pressure fluctuations during ink ejection.

[Configuration and operation of the invention] Features of the configuration of the present invention include an ink tank, a nozzle for ejecting ink in the ink tank into the space inside the ink tank, and a non-reactive gas atmosphere inside the ink tank. The present invention is a dissolved oxygen removal device having a gas source.

In the present invention, any nozzle that applies pressure to ink to eject it is sufficient. In addition, the non-reactive gas refers to a gas that does not react with the ink, such as nitrogen, argon, and helium. Then, when ink is ejected from a nozzle into an ink tank placed in this non-reactive gas atmosphere, dissolved oxygen in the ink is promoted to be released due to a sudden change in pressure applied to the ink at the time of ejection.

[Embodiment] An embodiment of the present invention will be described with reference to FIG. 1. In the figure, reference numeral 1 denotes an ink tank, which has a heating means 3 for heating the ink 2 in the ink tank l. Although the heating means 3 may be, for example, an electric heater, steam heating is preferable in order to prevent the ink 2 from burning due to excessive heating. At the top of the ink tank l,
A valve VI is connected to naturally release the gas in the ink tank l. A valve v2 is provided at the bottom of the ink tank l for taking out the ink 2 that has been processed. Further, a temperature sensor sl for sensing the temperature of the ink 2 is provided in the ink tank l. This temperature sensor S
1 is connected to a temperature measuring device 4, and a temperature sensor S
The temperature of the ink 2 can be detected by a temperature measuring device 4 based on the signal from L. A controller C0 is connected to the temperature measuring device 4, and this controller C1 controls the heating means 3 based on a signal from the temperature measuring device 4.

Inside the ink tank 1, a nozzle 5 is provided that projects upward from the bottom of the ink tank 1, for spouting the ink 2 into a space inside the ink tank 1 in the form of a fountain. At the base of this nozzle 5, raw material containers 6.7 containing raw materials for the ink 2 are provided with valves v3 and 7, respectively.
．． V4 and a flow meter 8. Valve V
3, V4 and flow meter 8 are connected to controller C2.

Based on the signal from the flow meter 8, the controller C2 controls the valve v3 so that each ink raw material is supplied at a predetermined mixing ratio.
The opening degree of +V4 is controlled and both valves v3 and v4 are closed after supplying a constant flow rate. Nozzle 5
The ink raw material sent in this way is ejected into the ink tank 1 by the gas pressure of the non-reactive gas from the gas source 9 such as a liquefied gas cylinder, and the ink 2 in the ink tank 1 is also circulated. It is something that makes you squirt.

On the other hand, a dissolved oxygen sensor S2 that senses dissolved oxygen in the ink 2 is provided in the ink tank 1. This dissolved oxygen sensor S2 is connected to the dissolved oxygen measuring device 10, and the dissolved oxygen concentration in the ink 2 is detected by the dissolved oxygen measuring device 10 based on a signal from the dissolved oxygen sensor s2. The dissolved oxygen measuring device 10 includes a controller c.
3 is connected, and this controller C3 controls the opening and closing of the valve V2 based on the signal from the dissolved oxygen measuring device 1o. In addition, a normal dissolved oxygen meter (D, 0. meter), etc. can be used as the dissolved oxygen sensor S2 and the dissolved oxygen measuring device 1O for detecting dissolved oxygen.Next, to explain its operation, the valve v1 is When opening, valve v3. When V4 is opened and ink raw materials are supplied, they are mixed and ejected from the nozzle 5 by the gas pressure of the non-reactive gas from the gas source 9. After a predetermined amount of ink 2 is supplied to the ink tank 1, the valve V3. v4
is closed, but the ink 2 in the ink tank 1 is circulated and ejected from the nozzle 5. At the same time, the air in the ink tank 1 is expelled from the valve V1 by the non-reactive gas ejected from the nozzle 5 together with the ink 2.

As mentioned above, the ink tank l is under a non-reactive gas atmosphere.
When the ink 2 is ejected from the nozzle 5 within the ink 2, dissolved oxygen in the ink 2 is released due to pressure fluctuations that act rapidly on the ink 2 when the ink 2 is ejected. That is, the ink 2, which is under pressure in the nozzle 5 due to the non-reactive gas pressure, is released from this pressure the moment it is ejected from the nozzle 5, and this pressure fluctuation promotes the release of dissolved oxygen.

The released oxygen is then discharged from the valve V1 together with the ink 2 and the non-reactive gas ejected from the nozzle 5.

In order to improve the effect of promoting the release of dissolved oxygen, it is preferable that the pressure difference between the ink 2 before and after being ejected from the nozzle 5 is as large as possible. Specifically, the pressure difference between the ink 2 before and after ejecting from the nozzle 5 is O, 1 kg/cm2.
As mentioned above, it is optimally preferably 0.3 kg/cW2 or more.

Although the heating means 3 is not necessarily necessary, if the heating means 3 is provided to heat the ink 2, it is possible to create an atmosphere in which gas is difficult to dissolve in the liquid due to the temperature, and the ink 2
This is preferable because it can promote the release of dissolved oxygen inside.

In this case, the heating temperature must be within a range that does not alter the quality of the ink 2, and although it varies depending on the type of ink, it is generally about 35 to 80°C. temperature sensor sl
may be a device that senses the temperature of the space inside the ink tank 1 or the temperature of the heating means 3, but it is preferable that the device directly senses the temperature of the ink 2 in order to ensure accurate temperature control. .

In this way, the dissolved oxygen removal process in the ink 2 continues, and when it is confirmed via the dissolved oxygen sensor S2 that the dissolved oxygen concentration has fallen below a predetermined level, the controller C3 opens the valve v2. This is to send the ink 2 to the next process. Therefore, the dissolved oxygen concentration in the ink 2 can be reliably kept below a predetermined level. The permissible level of dissolved oxygen varies depending on the composition of the ink, but
Especially in the case of ink for inkjet recording method, 15pp
It is preferable that it is below m.

The nozzle 5 in this embodiment is configured to spray the ink 2 up in a fountain shape using the non-reactive gas pressure from the gas source 9, but the ink 2 may be sprayed or sprayed from the top of the ink tank l in a shower shape. It may be something. Also,
The ink 2 may be ejected from the nozzle 5 by a pump or the like, and the non-reactive gas may be supplied by separately connecting a gas source 9 to the ink tank 1.

In this embodiment, the valve vl simply opens the inside of the ink tank l to the outside.

This valve v1 can also be further connected to exhaust means (not shown) such as a pump. In particular, if an exhaust means is provided, not only will air be more reliably removed from the ink tank 1, but if the inside of the ink tank 1 is depressurized by the exhaust means, the dissolved oxygen in the ink 2 will also be released due to this reduced pressure atmosphere. It has the advantage of being able to encourage Furthermore, in this embodiment, the ink raw materials are supplied to the nozzle 5 at a predetermined mixing ratio, and the ink 2 is simultaneously stirred and mixed in the ink tank l. Of course, it may be supplied.

Next, an experimental example of the apparatus according to the present invention will be explained.

10 fL of the premixed ink was supplied to the apparatus as described in FIG. 1, and the process was continued for 120 minutes to eject the ink from the nozzle at a rate of 0.217 minutes without applying heat. The non-reactive gas is nitrogen gas, and the pressure difference between the ink before and after it is ejected from the nozzle is approximately 1.0 kg.
/cm2. The ink used was an inkjet recording ink whose composition components were water-soluble dye, water, and glycols, and the experiment was conducted at atmospheric pressure. 52 tmt
The test was carried out under aHg and room temperature of 18°C.

As a result, the dissolved oxygen concentration in the ink before treatment was 21 ppm.
However, it decreased to 8 ppm after treatment.

[Effects of the Invention] According to the present invention, dissolved oxygen in the ink is released by rapid pressure fluctuations applied to the ink by ejecting the ink from a nozzle in a non-reactive gas atmosphere. Even if the ink itself contains a large amount of dissolved oxygen, the dissolved oxygen concentration in the ink can be made extremely low. Therefore, there is little concern that the ink will deteriorate due to oxidation of the ink composition components due to dissolved oxygen, and good ink storage stability can be obtained over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of an ink dissolved oxygen removal device according to the present invention. 1: ink tank, 2: ink, 3: heating means, 4: temperature measuring device, 5: nozzle, 6.7: raw material container, 8: flow meter, 9: gas source. lO: Dissolved oxygen measuring device, ■, ~V4: Valve, Sl
: Temperature sensor, S2: Dissolved oxygen sensor, 01-C3: Controller. Applicant Canon Co., Ltd. Agent Yutaka 1) Yoshio

Claims (1)

[Claims] l) An ink dissolved oxygen removal device comprising an ink tank, a nozzle for ejecting ink in the ink tank into a space inside the ink tank, and a gas source for creating a non-reactive gas atmosphere inside the ink tank.