GB2140021A

GB2140021A - Ink manufacturing system

Info

Publication number: GB2140021A
Application number: GB08408462A
Authority: GB
Inventors: Masahiro Haruta; Kunitaka Ozawa; Takashi Hamamoto
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1983-04-04
Filing date: 1984-04-02
Publication date: 1984-11-21
Also published as: DE3412426A1; HK71991A; FR2543450A1; DE3412426C2; GB2140021B; GB8408462D0; FR2543450B1

Abstract

An ink manufacturing system is provided with a dyestuff solution manufacturing section for manufacturing a dyestuff solution in which the concentration of inorganic salts is controlled, and an ink preparing section for preparing ink from the dyestuff solution supplied from the manufacturing section.

Description

SPECIFICATION Ink manufacturing system This invention relates to an ink manufacturing system, and more particularly, to an ink manufacturing system suitable for the preparation of recording liquid (generally referred to as ink) suited for ink jet recording or the like.

Ink to be used for an ink jet recording system which implements recording of information by ejecting ink within a recording head through an ejection orifice by means of vibrations transmitted from a piezo-electric vibrator or other expedients, employs various dyestuffs and pigments which are dissolved or dispersed in a liquid medium such as water or other (e.g. organic) solvent. Similar ink is used in writing implements such as felt pens, fountain pens, etc.

Such ink may comprise the following three chief components: water soluble dyestuff, water as the solvent for the dyestuff, and glycols as a desication-preventive agent.

The water-soluble dyestuff can contain a large amount of inorganic salts such as sodium chloride and sodium sulfate either as byproducts of the dye-synthesis, or as added salting-out agents, diluents, or level-dyeing agents.

We have discovered that when recording ink is prepared with use of dyestuff containing such inorganic salts, problems can arise: the inorganic salts can lower the solution stability of the dyestuff in the ink to bring about agglomeration and sedimentation of the dyestuff. Further, in the ink jet recording heads and writing implements, if and when the ink is evaporated in the vicinity of the ejection orifice causing the liquid composition to change, deposition of the inorganic salts can be induced. These phenomena cause clogging to take place at the discharge orifice which is highly undesirable.

We have found that by controlling the inorganic salt concentration within a predetermined maximum when producing the ink (in general, limited to 0.5 wt.% or less with respect to the total ink composition) these problems can be avoided. We have found such control to be indispensable when dyestuff available on the general market, which contains therein inorganic salts as impurities, is used for preparation of ink for the ink jet recording as well as for use in writing implements.

According to one aspect of the present invention, there is provided an ink manufacturing system characterized by the provision of a dyestuff solution manufacturing section for manufacturing a dyestuff solution in which the concentration of inorganic salts is controlled, and an ink preparing section for preparing ink from the dyestuff solution supplied from said manufacturing section.

According to another aspect of the present invention, there is provided an ink manufacturing system characterized by the provision of a dyestuff solution supply section having.

manufacturing means for manufacturing a dyestuff solution, dyestuff concentration control means for controlling the dyestuff concentration of the manufactured dyestuff solution, and inorganic salts concentration control means for controlling the inorganic salts concentration of said dyestuff solution, and an ink preparing section for preparing ink from the dyestuff solution supplied from said dyestuff solution supply section.

According to a further aspect of the present invention, there is provided an ink manufacturing system characterized by the provision of a dyestuff solution manufacturing section for manufacturing a dyestuff solution in which the concentration of inorganic salts is controlled, an ink preparing section for preparing ink from the dyestuff solution supplied from said manufacturing section, and dyestuff concentration detecting means in said preparing section.

According to still a further aspect of the present invention, there is provided an ink manufacturing system characterized by the provision of a dyestuff solution manufacturing section for manufacturing a dyestuff solution in which the concentration of inorganic salts is controlled, an ink preparing section for preparing ink from the dyestuff solution supplied from said manufacturing section, and inorganic salts concentration detecting means in said preparing section.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an embodiment of the system according to the present invention.

Fig. 2 is a schematic view showing the dyestuff refining section in the system of Fig.

1.

Fig. 3 is composed of Figs. 3A and 3B.

Figs. 3A and 3B are block diagrams showing the control unit of the system shown in Fig. 1.

Fig. 4 is composed of Figs. 4A and 4B.

Figs. 4A and 4B are flow charts showing the operation of the dyestuff refining section shown in Fig. 2.

DESCRIPTION OF THE PREFERRED EMBODI MENT The present invention will hereinafter be described in detail by reference to the drawings.

Figure 1 shows an embodiment of the ink manufacturing system according to the present invention. In Figure 1, reference numeral 1 designates an ink preparation tank to which aqueous solution of refined dyestuff is supplied from a dyestuff refining section 2 through a valve 3, as will later be described.

A water-soluble organic solvent and an additive are supplied from a reservoir 4 and a reservoir 5, respectively, to the preparation tank 1 through valves 6 and 7, respectively.

Further, pure water is supplied to the preparation tank 1 through a valve 8. These supplied materials are agitated by an agitator 9 to prepare an ink.

The quantity of ink manufactured in the preparation tank 1 is detected by a liquid quantity sensor 10. Also, the dyestuff concentration and the inorganic salts concentration in the ink prepared in the preparation tank 1 are detected by a dyestuff concentration sensor 11 and an inorganic salts concentration sensor 12, respectively. The final property control (lot control) of the prepared ink is effected on the basis of the outputs of these two sensors.

The ink whose components have been prepared to desired values is discharged through a discharge valve 13, as required.

Figure 2 shows the construction of the dyestuff refining section in the apparatus of Figure 1.

In Figure 2, a reference numeral 21 designates a dyestuff feeding section storing therein dyestuff powder 22. The dyestuff powder 22 is fed from this dyestuff feeding section 21 into a preparation tank 24 through a dyestuff feeding valve 23. Also, into this preparation tank 24, pure water is supplied through a pure feeding pipe 26 having a pure water valve 25 interposed in one part thereof.

In this preparation tank 24, aqueous solution of dyestuff is prepared by mixing and dissolving the dyestuff powder 22 and the pure water by means of an agitator 27 installed in the preparation tank 24. The liquid quantity of the aqueous solution of dyestuff staying in the preparation tank 24 is detected by a liquid quantity sensor 28 set in the preparation tank. The aqueous solution of dyestuff obtained in the preparation tank contains therein, as the residue, particles of the dyestuff powder which have not been dissolved in the pure water. This residual dyestuff powder is removed by a filter 29. For the filter 29, there may be used ordinary filter paper or "FLUOROPORE" (a trade name of a product of Sumitomo Denko K.K., Japan, which is made up of polytetrafluoroethylene as the principal constituent), and so forth.The aqueous solution of dyestuff, from which the residual particles, etc. have been removed through the filter 29, is forwarded to a feeding tank 31.

The aqueous solution of the dyestuff sent into the feeding tank 31 stays therein so far as a feeding valve 32 is in a closed state. A liquid level controlling valve 33 is disposed in this feeding tank 31 to maintain the quantity of the aqueous solution of dyestuff to be stored in it to a certain definite level or below.

A reference numeral 41 designates a refining section where the inorganic salts are removed from the aqueous solution of dyestuff..

In this refining section 41, a reference numeral 42 designates a salt-stripping tank, a numeral 43 refers to a saltstripping filter, and a numeral 44 represents a discharged salt storing tank. The aqueous solution of dyestuff is fed into the salt-stripping tank 42 through the feeding valve 32. The thus fed dyestuff solution is agitated by an agitator 45 set in the salt-stripping tank 42 to homogenize the aqueous solution, after which concentration of the inorganic salts therein is detected by a sensor 46 for the inorganic salts concentration. This detection of the inorganic salts concentration is carried out by, for example, the ion-chromatographic method. Further, concentration of the dyestuff in the aqueous solution is detected by use of a sensor 47 for the dyestuff concentration. This detection of the dyestuff concentration is carried out by, for example, the spectrophotometry.As will be described later, when the concentration of the inorganic salts is found to be above a predetermined value (e.g., 5 wt % with respect to the dyestuff), a circulation pump 48 is operated to circulate the aqueous solution of dyestuff in the salt-stripping tank 42 through the salt-stripping filter 43. For the salt-stripping filter, there may be used, for example, an ultraffilter, a reverse osmotic filter and so forth. By passage of the dyestuff solution through the saltstripping filter 43, the inorganic salts such as sodium chloride, sodium sulfate, etc. contained in it are filtered out in the form of aqueous solution of these salts, and discharged into the salt-storing tank 44. As the result of this salt removal, a part of the water as the solvent for the dyestuff is also discharged into this salt-storing tank 44 along with the inorganic salts.In order, therefore, to replenish water for the portion as discharged and to maintain a desired concentration for the dyestuff solution in the saltstripping tank 42, pure water is supplied into this salt-stripping tank 42 through a valve 49.

In the above-described manner, there can be obtained the aqueous dyestuff solution in the saltstripping tank 42 with the concentration of both inorganic salts and dyestuff being in their predetermined range. By the way, the quantity of the aqueous solution of dyestuff in the salt-stripping tank 42 is detected by a sensor 50 for the liquid quantity in the saltstripping tank.

Thereafter, the aqueous solution of dyestuff which has been refined (stripped off its salts content) in the above-described manner is discharged into a refined dyestuff storing tank 52 through a storage valve 51, and stored in it. The dyestuff aqueous solution in the storage tank 52, as shown in Figure 1, is supplied to the preparation tank 1 by the opening-closing control of the valve 3 and used for the preparation of ink.

Figure 3 shows the control system of the system shown in Figure 1.

In Figure 3, reference numeral 61 designates a controller which governs the driving and control of various sections. Reference numeral 62 denotes a read-only memory (ROM) in which is stored the control program such as the operation procedure shown in Figure 4. Reference numeral 63 designates a random access memory (RAM) in which various data are temporally stored.

In the present embodiment, analog signals are put out from the inorganic salts concentration sensors 12, 46 and the dyestuff concentration sensors 11, 47 and are converted into digital signals through A/D converters 64, 65 and 66, 67, respectively, whereafter they are supplied to the controller 61 through an input buffer circuit 68. On the other hand, digital signals are put out from the ink preparation tank liquid quantity sensor 10, the preparation tank liquid quantity sensor 28, and the salt-stripping tank liquid quantity sensor 50, and are supplied to the controller 61 through the input buffer circuit 68.

Reference numerals 71-84 designate drive circuits for driving the aforementioned valves 3, 6, 7, 8, 13, 23, 25, 49, 32, and 51, the agitators 9, 27, and 45, and the circulation pump 48, respectively. These drive circuits 71-84 are "ON-OFF" controlled by drive signals supplied from the controller 61 through an output buffer circuit 85.

Reference numerals 86 and 87 denote a dyestuff concentration range setting switch and an inorganic salts concentration range setting switch, respectively. Signals corresponding to the concentration ranges set by these switches are supplied to the controller 61 through a console input-output buffer circuit 88. Reference numerals 89 and 90 designate dyestuff concentration display devices, and reference numerals 91 and 92 denote inorganic salts concentration display devices.

The dyestuff concentration value and the inorganic salts concentration value in the dyestuff aqueous solution being refined are displayed by the display devices 89 and 91, respectively. As a result, the operator of the ink manufacturing system can readily know the quality of the ink during its production. Also, the dyestuff concentration value and the inorganic salts concentration value in the ink as the final product obtained in the ink preparation tank 1 are displayed by the display devices 90 and 92, respectively. Thus, the operator can carry out the property control (lot control) of the ink manufactured.

The set values of the dyestuff concentration range and the inorganic salts concentration range by the switches 86 and 87, respectively, are temporally stored in the RAM 63.

The detection concentration values of the inorganic salts and dyestuff of the dyestuff aqueous solution during the refining operation, as detected by the inorganic salts concentration sensor 46 and the dyestuff concentration sensor 47, respectively, are compared with the set values in a comparison section 611 of the controller 61 and, on the basis of the result of the comparison, driving of various loads such as the circulation pump 48 is controlled as will later be described.

Reference numeral 93 designates a printer adapted to be switched on or off by a drive circuit 95 controlled by the controller 61 through an output buffer circuit 94 and to print out the concentration values detected by the dyestuff concentration sensors 11, 47 and the inorganic salts concentration sensors 12, 46, at predetermined time intervals.

Figure 4 shows the operation flow of the dyestuff refining system 2 shown in Figure 2.

In Figure 4, steps ST1-ST4 are for maintaining the dyestuff aqueous solution in the preparation tank 24 at a constant quantity. In more detail, at the step ST1, the detection is performed with an output from the sensor 28 for the liquid quantity in the preparation tank as to whether the liquid level of the aqueous solution of dyestuff in the preparntion tank 24 is above a lower position defining a predetermined set range of the liquid level. If the liquid level is below the lower position, the operational sequence proceeds to the step ST2; otherwise, to the step ST3. At the step ST2, the dyestuff feeding valve 23 and the pure water feeding valve 25 are opened to fill the preparation tank 24 with predetermined quantities of the dyestuff powder and the pure water.In the preparation tank 24, since the agitator 27 is in constant operation, the dyestuff powder as charged is dissolved into the pure water to be the aqueous solution of dyestuff. At the step ST3, detection is performed with an output from the liquid quantity sensor 28 as to whether the liquid surface level in the preparation tank 24 is above an upper position defining the predetermined set range, or not. If above the upper position, the operational sequence proceeds to the step ST4, and, if not, to the step ST5. At the step ST4, the dyestuff feeding valve 23 and the pure water feeding valve 25 in their open condition are closed to thereby stop feeding of the dyestuff powder and the pure water.

At a step ST5, a dyestuff concentration value of the dyestuff solution in the saltstripping tank 42 as detected by the dyestuff concentration sensor 47 is displayed on the display device 90. In the same manner, at a step ST6, an inorganic salts concentration value as detected by the inorganic salts concentration sensor 46 is displayed on the display device 92.

At a step ST7, determination is made as to whether the dyestuff concentration as detected by the detector 47 is within the range of the dyestuff concentration set by the switch 86, or not. If it is within the set range, the operational sequence proceeds to a step ST8, and, if not, to a step ST9. At the step ST8, determination is made as to whether the inorganic salts concentration as detected by the sensor 46 is within the range of values set by the switch 87, or not. If it is within the set range, the operational sequence proceeds to a step ST10, and, if not, to the step ST9.

At the step ST9, determination is made as to whether the liquid surface level in the saltstripping tank 42 as detected by the sensor 50 is above the upper position defining the set range, or not. If it is below the upper position, the operational sequence proceeds to a step ST11, and, if not, to a step ST12. At the step STl 1, the feeding valve 32 and the pure water feeding valve 49 are subjected to open-and-close controls, thereby feeding the aqueous solution of dyestuff and the pure water into the salt-stripping tank 42, thereby regulating the dyestuff concentration of the aqueous dyestuff solution in the salt-stripping tank 42 to be in the range set by the switch 86 as mentioned in the foregoing. After this, the operational sequence proceeds to a step ST13.On the other hand, closing operations of the feeding valve 32 and the pure water feeding valve 49 are carried out at the step ST12.

At the step ST13, the circulation pump 48 is operated to circulate the aqueous solution of dyestuff in the salt-stripping tank 42 through the saltstripping filter 43 to thereby perform elimination of the inorganic salts from the aqueous solution of dyestuff.

As stated above, when the dyestuff concentration and the inorganic salts concentration are outside the set ranges, routine operations are repeated through the steps ST11 and ST13 or the steps Sty 2 and ST13 so as to bring the dyestuff concentration and the inorganic salts concentration within their set ranges. After these two concentration values have been put in the set ranges, the operational sequence proceeds to the Step ST10.

At the step ST10, determination is made as to whether the liquid surface level in the saltstripping tank 42 as detected by the sensor 50 is above the lower position defining the set range, or not. If it is above the lower position, the operational sequence proceeds to a step 14, and, if not, to a step ST15. At the step ST14, the operation of the circulation pump 48 is stopped and the opening operation of the storing valve 51 is carried out. As the result of this, a predetermined quantity of the refined aqueous dyestuff solution obtained in the salt-stripping tank 42 is supplied into the storage tank 52.

At the step ST15, there are effected the closing operation of the storing valve 51 and the opening operations of the feeding valve 32 and the pure water feeding valve 49, thereby completing supply of the refined solution to the storage tank 52 and increasing the quantity of the aqueous dyestuff solution in the salt-stripping tank 42 so as to bring the liquid surface level within the set range.

Thereafter, the routine operations are again repeated through the steps ST11 and Sty 3 or through the steps ST12 and ST13 as mentioned in the foregoing, thereby obtaining in the salt-stripping tank 42 a predetermined quantity of aqueous solution of dyestuff with the dyestuff concentration and the inorganic salts concentration thereof being within the set ranges. After this, the operational sequence proceeds to the step ST14.

As described above, in the present embodiment, the dyestuff aqueous solution is refined for every certain definite quantity in the refining section 41 and therefore, the refined dyestuff aqueous solution can be continuously supplied from the dyestuff refining section 2 to the preparation tank 1 and ink can be continuously made from the refined dyestuff aqueous solution in the preparation tank 1.

In the above-described embodiment, design is made such that the detected value of the dyestuff concentration is printed and output at predetermined time intervals, whereas the present invention is not restricted thereto. For example, the detected value may be stored in the RAM so that it may be printed and output at a desired period by operation of a print command key provided in the operating section.

Also, in the above-described embodiment, design is made such that the detected value of the inorganic salts concentration is printed and output at predetermined time intervals, whereas the present invention is not restricted thereto. For example, the detected value may be stored in the RAM so that it may be printed and output at a desired period by operation of a print command key provided in the operating section.

Further, in the above-described embodiment, design is made such that the detected value of the dyestuff concentration is displayed at all times and printed and output at predetermined time intervals, whereas the present invention is not restricted thereto. For example, a change-over key may be disposed in the operating section so that one of the display of the detected value and the printingoutputting of the detected value can be effected as required.

Furthermore, in the above-described embodiment, design is made such that the detected value of the inorganic salts concentration is displayed at all times and printed and output at predetermined time intervals, whereas the present invention is not restricted thereto. For example, a change-over key may be disposed in the operating section so that one of the display of the detected value and the printing-outputting of the detected value can be effected as required.

As described above, the system of the present invention has the following effect.

Ink stable in quality when used for ink jet recording or the like can be continuously and automatically manufactured.

The final product can be effected on the basis of the result cf the detection, and ink stable in quality when used for ink jet recording or the like can be prepared.

The property of the ink which is the final product can be controlled on the basis of the display, and ink stable in quality when used for ink jet recording or the like can be prepared.

The property of the ink which is the final product can be controlled by the recording, and ink stable in quality when used for ink jet recording or the like can be prepared.

The current control of the property of the ink which is the final product can be effected by the displayed value and the state of the ink varied with time can be confirmed by the recorded value, and ink stable in quality when used for ink jet recording or the like can be prepared.

Claims

1. An ink manufacturing system characterized by the provision of a dyestuff solution manufacturing section for manufacturing a dyestuff solution in which the concentration of inorganic salts is controlled, and an ink preparing section for preparing ink from the dyestuff solution supplied from said manufacturing section.

2. An ink manufacturing system according to Claim 1, wherein dyestuff refining means for eliminating the inorganic salts in the dyestuff solution is disposed in said dyestuff solution manufacturing section.

3. An ink manufacturing system according to Claim 1, wherein means for detecting the concentration of inorganic salts is disposed in said dyestuff solution manufacturing section.

4. An ink manufacturing system characterized by the provision of a dyestuff solution supply section having manufacturing means for manufacturing a dyestuff solution, dyestuff concentration control means for controlling the dyestuff concentration of the manufactured dyestuff solution and inorganic salts concentration control means for controlling the inorganic salts concentration of said dyestuff solution, and an ink preparing section for preparing ink from the dyestuff solution supplied from said dyestuff solution supply section.

5. An ink manufacturing system characterized by the provision of a dyestuff solution manufacturing section for manufacturing a dyestuff solution in which the concentration of inorganic salts is controlled, an ink preparing section for preparing ink from the dyestuff solution supplied from said manuffacturing section, and dyestuff concentration detecting means in said preparing section.

6. An ink manufacturing system according to Claim 5, further provided with display means for displaying the detection output of said detecting means.

7. An ink manufacturing system according to Claim 5, further provided with recording means for recording the detection output of said detecting means.

8. An ink manufacturing system characterized by the provision of a dyestuff solution manufacturing section for manufacturing a dyestuff solution in which the concentration of inorganic salts is controlled, an ink preparing section for preparing ink from the dyestuff solution supplied from said ink manufacturing section, and inorganic salts concentration detecting means in said preparing section.

9. An ink manufacturing system according to Claim 8, further provided with display means for displaying the detection output of said detecting means.

10. An ink manufacturing system according to Claim 8, further provided with recording means for recording the detection output of said detecting means.

11. A system according to any preceding claim wherein the control means includes a salt stripping filter, and means for circulating the dyestuff solution through the filter when the detecting means indicates a specified salt concentration.

1 2. A system according to Claim 11 including means for detecting the concentration of dyestuff in the solution and means for replenishing water or other solvent removed by the filter to maintain the dyestuff concentration within a determined range.

1 3. An ink manufacturing system substantially as described herein with reference to the accompanying drawings.