JPS60210680A - Ink production device - Google Patents

Abstract

PURPOSE:To obtain ink which does not cause precipitation of any solid, by adjusting the pH of an aq. dye soln. and the pH of a solvent for ink to thereby keep the pH constant over a long period of time, thus keeping good dispersibility and thermal stability. CONSTITUTION:The pH of an aq. dye soln. 2 in a liquid tank 1 and the pH of a solvent 6 in a solvent tank 5 are detected by pH detectors 3, 7. The detected values are fed through A/D converters 18, 20 to a control device 10 and judged whether they are within the range of preset values. When they are out of the optimum pH range preset, valves 13, 16 for pH adjustor feed means 4, 8 are opened by the control device 10 to feed a pH adjustor 9. When they are within the optimum pH range preset, discharge valves 17, 19 are opened by the control device 10 to feed the dye soln. 2 and the solvent 6 to a ink preparing tank 21 where they are mixed with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field J] The present invention relates to an ink manufacturing apparatus, and more particularly to an ink manufacturing apparatus suitable for preparing recording liquid (generally referred to as ink) suitable for inkjet recording, writing instruments, and the like.

[Prior Art] Conventionally, ink used in an inkjet recording method in which recording is performed by ejecting ink in a recording tray V from an ejection orifice using vibrations caused by a piezo vibrator, etc., has been made by mixing various dyes and pigments with water or other materials. Those dissolved or dispersed in a liquid medium made of an organic solvent are known. It is also known that similar inks are used in writing instruments such as felt bezos and fountain pens.

Examples of general basic configurations of such ink are: 1.
The main ingredients include a water-soluble dye, water as its solvent, and the king of glycols as an anti-drying agent.

Conventionally, the pH of such inks is often adjusted to around neutrality in order to prevent adverse effects on the components of the recording device. However, such conventional inks can print at high speeds. Its physical properties were too poor to be used in recording devices.

In order to be used in a recording device that can print at high speeds, it is necessary that the ink ejection nozzle and other parts of the recording device do not become clogged or have solid matter deposited or adhered to them.
For this purpose, it is necessary that the dispersibility of the dye in the ink is stable over a long period of time, and that the ink has good thermal stability. However, from this point of view, little is known about the influence that the method of adjusting pH has on the properties of ink in the ink manufacturing process.

In the course of our research, the inventor found that depending on which stage of the ink manufacturing process the pH is adjusted, the dispersion of the pH 5 dye in the ink may occur over a long period of time even if the ink has the same pH immediately after manufacturing. It was found that they exhibited different behavior in terms of stability and thermal stability.

In other words, if the ink is adjusted once and then the pH is adjusted using a pH adjuster such as acid or alkali, the pH will change significantly after a long period of time, which will affect the dispersibility of the dye in the ink.
The thermal stability of the ink decreases. However, if the pH is adjusted before adjusting the ink and then the pH-adjusted dye aqueous solution and the pH-adjusted ink solvent are mixed,
It has been found that this ink is an excellent ink with small PH changes and the like.

The cause of the above phenomenon is unknown, but it may be due to the difference in the order of addition of the pH adjuster, the hydration state of water and glycol, the distribution state of the ink solvent around the dye molecules, and other factors. I imagine that there are.

[Objective of the Invention] The object of the present invention is to provide an ink discharge nozzle and other components of a recording device that does not change significantly in pH even after a long period of time has passed after ink adjustment, has excellent physical properties, and is capable of high-speed printing. It is an object of the present invention to provide an ink manufacturing device capable of manufacturing excellent ink that does not cause precipitation or adhesion of solids if it becomes clogged.

According to the present invention, there is provided a pH detecting means for detecting the pH of the dye aqueous solution and a pH detecting means for detecting the pH of the dye aqueous solution;
A dye aqueous solution tank equipped with an H adjuster supply means, a pH detecting means for detecting the pH of the ink solvent, and a pH detecting means for detecting the pH of the ink solvent.
There is provided an ink manufacturing apparatus characterized by comprising an ink solvent tank equipped with a pH adjuster supply means for supplying an H adjuster.

[Example] Next, the present invention will be described in detail with reference to examples shown in the drawings.

FIG. 1 is a schematic diagram showing an embodiment of an ink manufacturing apparatus according to the present invention. In FIG. 1, l is a dye aqueous solution tank, 2 is a dye aqueous solution, 3 is a pH detection means for the dye aqueous solution, and 4 is a dye aqueous solution tank.
5 is an ink solvent tank; 6 is an ink solvent; 7 is an ink solvent pH detection means; 8
9 is a pH adjuster supply means for the ink solvent; 9 is a pH adjuster;
lO is a control means.

The aqueous dye solution tank 1 stores an aqueous dye solution 2 prepared in advance to a certain concentration, and is equipped with a stirring means 11 for uniformly mixing the pH adjuster when it is added.

The pH adjusting agent supply means 4 adjusts the pH under the control of the control means IO.
It is for supplying the conditioning agent 9 into the dye aqueous solution 2, and has a storage section 12 and a supply valve 13.

The PH detection means 3 detects P)I of the dye aqueous solution 2 and transmits this data to the control means IO. 14 is a dye aqueous solution discharge means.

The ink solvent tank 5 stores an ink solvent 6 such as glycols or a mixture of glycols and water, and includes a stirring means 23 for uniformly mixing the pH adjuster 9 when it is added. We are prepared.

The pH adjuster supply means 8 adjusts the pH under the control of the control means 10.
This is for supplying the adjusting agent 9 into the ink solvent 6.

The pH detection means 7 detects the pH of the ink solvent and transmits this data to the control means 10. 15 is an ink-solvent discharge means.

The control means 10 includes the pg detection means 3. p) Connected to l regulator supply means 4 and dye aqueous solution discharge means 14, and dye aqueous solution 2
If the pH is not within a certain range, the valve 1B of the pH adjuster supply means 4 is automatically opened to control the pH within a certain range, and if the pH is within a certain range, the dye aqueous solution is discharged. Pulp of means 14! Open 7 and dye aqueous solution 2
It is something that discharges.

Further, the control means IO includes a pH detection means 7, a pH adjuster supply means 8. It is connected to the ink solvent discharge means 15, and when the pH of the ink solvent 6 is not within a certain range, the valve 18 of the pH adjusting agent supply means 8 is automatically opened to control the pH within a certain range, and the pH is If it is within a certain range, the valve 19 of the ink solvent discharge means 15 is opened to discharge the ink solvent 2. A flowchart of the control program is shown in FIG.

An aqueous dye solution 2 of a constant concentration prepared in advance is placed in an aqueous dye solution tank 1. First, the pH detection means 3 detects p)l of the dye aqueous solution. p) An analog signal is output from the I detection means 3, converted into a digital signal via the A/D converter 18, and then supplied to the control means IO.

Determine whether the A/D converter output is within a certain set level range (that is, determine whether it is within a predetermined pHti range), and if it is out of the set optimum pH range, control is performed. Under the control of the means 10, the valve 13 of the PH adjuster supply means 4 is opened, and the PH adjuster 9 is supplied to the dye aqueous solution 2.

If the pH is within the set optimum pH range, the control means 10
Under this control, the dye aqueous solution discharge valve 17 is opened and the dye aqueous solution 2 is supplied to the ink preparation tank 21. A timer (not shown) is started at the same time as the dye aqueous solution discharge valve 17 is opened, and when a predetermined time has elapsed (when the dye aqueous solution tank becomes empty), the dye aqueous solution discharge valve 17 is closed and the dye aqueous solution is supplied. An aqueous dye solution is supplied to the tank 1 by means (not shown), and a series of operations similar to those described above are repeated to adjust the pH of the aqueous dye solution.

On the other hand, the ink solvent tank 5 is filled with an ink solvent 6 in advance. First, the pH of the ink solvent 6 is determined by the pH detection means 7.
is detected. An analog signal is output from the pH detection means 7, converted into a digital signal via the A/D converter 2o, and then supplied to the control means 10. determining whether the A/D converter output is within a certain set level (i.e., determining whether it is within a predetermined pH range);
If the pH is out of the set optimum pH range, the valve 1 of the pH adjuster supply means 8 is controlled by the control means IO.
8 is opened and p)l regulator is supplied to the ink solvent 6.

If the pH is within the set optimum pH range, the control means lO
Under this control, the ink solvent discharge valve 19 is opened and the ink solvent 6 is supplied to the ink mixing tank 21. A timer (not shown) is started at the same time as the ink solvent discharge valve 18 is opened, and when a predetermined time has elapsed (when the ink solvent tank becomes empty), the ink solvent discharge valve 19 is closed to supply ink solvent. The ink solvent is supplied to the ink solvent tank 5 by means (not shown), and the same series of operations as described above are repeated to adjust the pH of the ink solvent.

After the pH is adjusted to within a predetermined range as described above, the dye aqueous solution supplied to the ink preparation tank 21 and the ink solvent are mixed and prepared. Mixing is done by stirring means 22. After blending, if necessary, the ink is filtered through a membrane filter or the like.

The pH adjuster is preferably a basic compound, such as ammonia, sodium hydroxide, sodium carbonate, potassium carbonate, potassium hydroxide, jetanolamine, triethanolamine, and the like. These are used as such or in solution.

Although a stirring blade is used as the stirring means 11.22 in FIG. 1, it is also possible to spray the raw material in a fountain shape, to shake the tanks 1 and 5.21, or to use ultrasonic waves. Furthermore, any combination of these is also possible.

Next, an experimental example will be given.

Experimental Example 1 Glycerin 5 Ethylene Glycol 20 Ion-exchanged water 70 Sodium carbonate When preparing an ink with an appropriate composition, the dye and ion-exchanged water are mixed in the dye aqueous solution tank 1, stirred for 3 hours, and then added to the pH adjuster supply means 4. Sodium carbonate was added as a pi:lJ adjuster to adjust the pH to 9.5. On the other hand, the solvent (glycerin and ethylene glycol) and ion-exchanged water were mixed in the ink solvent tank 5 and stirred for 3 hours, and sodium carbonate as a pH adjuster was added by the P)I adjuster supply means 8.
The po was adjusted to 8.5.

Next, the pH-adjusted dye aqueous solution and the pH-adjusted ink solvent were discharged into the ink preparation tank 21 from the discharge valve 17.19, mixed, and stirred for 3 hours. Q. The ink was completed by filtration with a 331L membrane filter (not shown). An ink with pH=9.3 was obtained.

As a comparative example, the above composition was mixed except for sodium carbonate, and stirred for 9 hours. Sodium carbonate was appropriately added thereto to adjust the pH to 9.3. Finally, the ink was completed by filtration through a 0.331 L membrane filter.

When the above two types of ink were stored at 75°C, the results were as follows.

As described above, the ink obtained by the apparatus of the present invention has a pH of
It was found that the stability over time was good.

Experimental Example 2 °6'' composition,, 96 7 artrazine [Daiwa Kasei @] 4-isolated triethylene glycol 20 Ethylene glycol lO Ion exchange water 86 Sodium hydroxide When creating an ink with an appropriate or higher composition, in the dye aqueous solution tank l The dye and ion-exchanged water were mixed and stirred for 2 hours, and sodium hydroxide was added as a pH adjuster using the pH adjuster supply means 4 to adjust the pH to 8.5.Meanwhile, in the ink solvent tank 5, Mix the solvent (triethylene glycol and ethylene glycol) and ion exchange water, stir for 2 hours, and
Sodium hydroxide as a pH adjuster was added by the H adjuster supply means 8 to adjust the pH to 8.5. Next, the dye aqueous solution and pH adjusted by the discharge valve 17゜lθ were added.
The adjusted ink solvent was discharged into the ink solvent tank 21, mixed, and stirred for 1 to 3 hours. 0.33. The ink was completed by filtration through a membrane filter (not shown).
An ink with pH=9.3 was obtained.

As a comparative example, the above composition was mixed except for sodium hydroxide, stirred for 6 hours, and sodium hydroxide was appropriately added thereto to adjust the pH to 9.3. Finally, the ink was completed by filtration through a 0.331 L membrane filter.

When the above two types of ink were stored at 75°C, the results were as follows.

It was found that pH stability over time was good.

[Effects of the Invention] According to the apparatus of the present invention, even after a long period of time has elapsed after ink preparation, p.
H does not change significantly, the dispersibility of the dye in the ink and the thermal stability of the ink do not deteriorate, and therefore high speed printing is possible. Excellent ink that does not cause precipitation or adhesion can be easily produced.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an ink manufacturing apparatus according to the present invention, and FIG. 2 is a flowchart of a control program of the control means in FIG. 1. l...Dye aqueous solution tank 2...Dye aqueous solution 3...P)l detection means 4 for the dye aqueous solution...pHafli agent supply means 5 for the dye aqueous solution...
・Ink solvent tank. 6... Ink solvent 7... In-1 solvent pH detection means 8... Ink solvent pi adjuster supply means 9... pH
Adjustment agent 10...control means 11...stirring means 12...reservoir 13...supply valve 14...dye aqueous solution discharge means 15...ink solvent discharge means 1B...pH adjuster supply Valve 17... Dye aqueous solution discharge valve 18... A/D converter 19... Ink solvent discharge valve 20... A/El converter 21... Ink preparation tank 22... Stirring means 23. ...Stirring means applicant Yutaka, agent of Canon Co., Ltd. 1) Yu Yoshio Figure 1 0

Claims (1)

[Claims] A dye aqueous solution tank equipped with a pH detection means for detecting the pH of the dye aqueous solution and a pH adjuster supply means for supplying a pH adjuster to the dye aqueous solution, and a P for detecting the pH of the ink solvent.
Supplying pH adjuster to H detection means and ink solventp)l
An ink manufacturing apparatus comprising an ink solvent tank equipped with a regulating agent supply means.