JP2011005717A - Liquid jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printer that can equalize densities of settling materials having density differences in a short period of time in the inkjet printer, that intermittently supplies liquid including the settling materials such as a colorant to ink via an ink supply pipe.SOLUTION: This inkjet printer includes an agitating container having an ink agitating means that is inserted into the ink supply pipe at a portion in the vicinity of a print head, the ink supply pipe coupling an ink tank to the print head. The agitating container is provided with an ink blocking means for blocking flow-in of ink from the ink supply pipe, and an ink supply means that opens the blocking means and supplies ink to the agitating container through the ink supply pipe when an amount of ink in the agitating container becomes lower than a predetermined value.

Description

The present invention relates to a liquid jet printer in which supply of a liquid having a reduced concentration due to precipitation to a print head is reduced by installing a liquid stirring means on the carriage.

FIG. 11 shows an ink jet printing apparatus equipped with a conventional ink supply mechanism, and the following configuration is known as a print mechanism of the ink jet printer (arrangement relationship between an ink tank, a print head, and an ink supply tube). (See Patent Document 1)
In FIG. 11, an ink jet printing apparatus 1 is provided inside a printing mechanism and provided on a carriage 11 on which a printing head (not shown) is mounted, and is provided outside a printing mechanism and a pressure adjusting unit 12 made of a diaphragm. An ink tank 15 for storing ink to be supplied to a print head mounted on the carriage 11 via the pressure adjustment unit 13, the pressure adjustment unit 13, the ink supply tube 14, and the pressure adjustment unit 12, and the print head and pressure adjustment unit 12 are mounted. A carriage drive belt 17 for driving the carriage 11 along the carriage guide 16, a carriage drive motor 18 for driving the carriage drive belt 17, and a print sheet conveyance guide portion 19 for conveying the print sheet to the print position. It is configured.

The carriage drive motor 18 is driven by a control signal from a host device (not shown) and the carriage drive belt 17 is driven, so that the carriage 11 on which the print head and the pressure adjusting unit 12 are mounted follows the carriage guide 16. Printing is performed on the printing paper conveyed from the printing paper conveyance guide unit 19 by reciprocating to a predetermined printing position.

At that time, the ink supply tube 1 connected to the pressure adjustment unit 12 mounted on the carriage 11.
4 bends flexibly with the moving carriage 11. There is a difference in the size of the pressure adjusting units 12 and 13, the pressure adjusting unit 12 provided on the carriage 11 is light and small, and the pressure adjusting unit 13 is large and maximizes the effect of suppressing pressure fluctuation. It has a structure that can be taken.

In recent years, in outdoor printing, it has become the mainstream to use pigment inks that are more durable than dye inks. For example, in the conventional printing apparatus (inkjet printer) shown in FIG. 11, a supply tube (capillary tube) is used to supply ink from an ink tank containing a color material such as a pigment to the print head. Although both are connected via, the supply tube was normally arrange | positioned in the state extended flatly so that the space | interval of both might be tied as short as possible.
Inkjet printers may not be used continuously but may be used intermittently after several days or more of rest periods, but if there is a gap, they are used for inkjet printers. There is a problem that color material ink (for example, white ink) settles, causing non-uniform print density, ejection failure, nozzle clogging, and the like. In particular, in the case of an inorganic color material such as titanium oxide used as a color material for white ink, there is a problem that the ink tends to settle during a period in which the ink does not flow (rest period).

In the latter case, that is, in the case of the special color ink such as white ink or metallic luster, it is general that the color material component particles are heavy and the dispersion type ink tends to settle. In particular, in the case of such a dispersion type ink, when the ink jet apparatus does not operate for several hours, precipitation may be manifested in an ink supply cartridge mounted in the ink jet apparatus, and ejection failure may occur. The following are known to prevent this. (See Patent Document 2)
“(1) An ink cartridge that stores ink that is cured by irradiation of active energy, and includes the stored ink stirring member inside the stored ink.
(2) The ink cartridge according to (1), wherein the stored ink stirring member is a magnetic rotor.
(3) An active energy curable ink jet recording apparatus that forms an image of ink that is cured by irradiation of active energy on a recording medium by ink jet, the image recording unit having an ink jet head that discharges the ink onto the recording medium; An ink cartridge having a stirring member inside the stored ink is detachable; a cartridge mounting portion for supplying the ink to the ink jet head when the ink cartridge is mounted; and the ink jet recording corresponding to the stirring member when the cartridge is mounted An active energy curable ink jet recording apparatus provided with an agitating member driving unit that is disposed on the apparatus side and that can operate the agitating member at a predetermined timing. "

JP2001-80088 JP 2006-326929 A

The one described in Patent Document 2 stirs the precipitation of ink (white ink or metallic glossy ink) in the cartridge, and is an ink arranged horizontally between the ink tank (cartridge) and the print head. In fact, no consideration has been given to the sediment deposited in the supply pipe.

FIG. 6 shows the problem when the color material (titanium oxide in this example) settles in the ink supply pipe.
Will be described.
FIG. 6A schematically shows a state where the ink tank (cassette) 1 and the ink head 2 are connected by a thin tube (ink supply tube) 3 disposed horizontally.

As shown in FIG. 6A, when the ink jet printer is in a resting state for a long period, the color material contained in the ink is settled as shown in 3a of FIG. 6A.
In the upper part of the thin tube 3, the ink 3b having a thin color material is in a supernatant state.

Here, when the ink jet printer is put into an operating state from a long period of inactivity and the ink is discharged (discharged) from the ink head 2, the ink in the state where the color material density in the upper portion in the narrow tube 3 is low for a while. 3b is mainly discharged (discharged).
Thereafter, as the ink 3b having a low color material concentration is discharged and the agitated ink is supplied from the ink tank, the portion in contact with the settled color material is gradually agitated. It takes a lot of time to mix with the ink and reach the desired colorant density.
If this is seen from the print result of the medium, since the printing with a light density that is not the intended color material density continues for a predetermined time, the printing state is not preferable, and this period (the desired color material density is obtained). During the period until the ink state is recovered, there is a problem that ink must be shot and discharged.

As a countermeasure against the sedimentation of the color material ink used in the ink jet printer, there is a countermeasure to mix the settled color material by vibrating the ink tank containing the ink or stirring the inside of the tank. No effective measures have been taken so far for the sedimentation of the pigment in the ink supply pipe between the ink tank and the print head.

  The applicant of the present application can level the difference in concentration of the sedimentary substance in an ink jet printer that intermittently supplies ink containing a sedimentary substance such as a coloring material via an ink supply tube. The following reference example (Japanese Patent Application No. 2008-286320) has been filed as an inkjet printer.

  An ink jet printer according to a reference example is an ink jet printer that records an image on a print medium by moving a carriage mounted with a print head back and forth in the main scan direction and moving the print medium in a direction perpendicular to the main scan direction. An ink agitation means inserted in the vicinity of the print head side of an ink supply pipe connecting the print head and the print head is installed in the carriage.

Further, the stirring means is a stirring container containing a stirring ball movable in the container, and stirs the ink precipitate as the carriage reciprocates.
Further, the stirring container is installed in an ink supply pipe corresponding to the color material ink.

Further, the ink supply tube is formed in a spiral shape or a circular shape as a region portion having a height difference in a direction in which the liquid is supplied and having a width larger than the inner diameter of the tube in at least a part of the tube. Features.
In addition, the ink supply pipe has a sign-like shape as a region (D) having a height difference in the direction of supplying the liquid having a width (H) larger than the inner diameter (r) of the pipe in at least a part of the pipe. Alternatively, it is formed in a wave shape.
The wave shape includes a sine wave (monotone wave) formed by a single frequency component and a composite wave formed by a plurality of frequency components.
It is desirable that the curved portion or the wavy slope is steeper in the descending direction than in the ascending direction of the liquid.
The inclination along the flow direction of the liquid is the upward direction (downward direction) means the inclination of the capillary tube when the liquid goes up or down when passing through the curved part or the wavy part. It gradually rises at the wavy part and falls abruptly.
Further, the liquid color material includes titanium oxide.

  An ink jet printer according to a reference example is an ink jet printer that records an image on a print medium by moving a carriage mounted with a print head back and forth in the main scan direction and moving the print medium in a direction perpendicular to the main scan direction. Since the ink agitating means inserted in the vicinity of the print head side of the ink supply pipe connecting the print head and the print head is installed in the carriage, the agitating means acts by the reciprocating movement of the carriage to agitate the ink. It is possible to reduce the time until the settled color material is uniformly mixed and reaches a normal color material density after a long rest period, and it is possible to reduce unnecessary ink consumption.

FIG. 3 is an external view showing an ink jet printer equipped with an ink supply mechanism of a reference example, showing the print mechanism of the ink jet printer (relation between an ink tank, a print head, and ink agitation means inserted in an ink supply path). It is.
In FIG. 3, the ink jet printing apparatus 1 includes a print head mounted on a carriage 11 via an ink supply tube 14 provided on a carriage 11 provided inside a printing mechanism and mounted with a print head (not shown). Ink tank 15 for storing ink to be supplied to
A carriage driving belt 17 for driving the carriage 11 on which the print head and the pressure adjusting unit 12 are mounted along the carriage guide 16; a carriage driving motor 18 for driving the carriage driving belt 17; and for transporting the printing paper to the printing position. Printing paper transport guide 1
9 is comprised.

The carriage drive motor 18 is driven by a control signal from a host device (not shown) and the carriage drive belt 17 is driven, so that the carriage 11 on which the print head and the pressure adjusting unit 12 are mounted follows the carriage guide 16. Printing is performed on the printing paper conveyed from the printing paper conveyance guide unit 19 by reciprocating to a predetermined printing position.

In FIG. 3, an ink agitation means 4, which is a characteristic part of the present invention, is installed (fixed) in the vicinity of the print head side (not shown) of the ink supply path 14 along the reciprocating direction of the carriage.
The ink stirring means is, for example, a laterally long container (stirring container) whose input and output ports are connected to the ink supply path, and a stirring ball that is movable inside the container fixed to the carriage. One or more are incorporated.
The ink in the container of the agitation means is agitated and the ink density is made uniform by moving the agitation sphere built in as the carriage reciprocates.

Next, a detailed example of the stirring container 4 of FIG. 3 will be described with reference to FIG.
In FIG. 4, 4 is an ink stirring container (stirring means) inserted in the vicinity of the print head side of the ink supply pipe 14 connecting the ink tank and the print head 2 (not shown). -2 are incorporated in a movable manner (not necessarily two).
It is desirable that the stirring ball be moved along the bottom of the stirring container because the precipitate of ink accumulates in the lower part of the container.

FIG. 5 is a graph for explaining the effect of mounting the ink stirring means (stirring container) of the reference example.
In FIG. 5, the vertical axis represents the whiteness of the ink ejected from the head, and the whiteness in a normal use state is assumed to be 0, and the whiteness reduction rate is shown.
The horizontal axis indicates the ink consumption until the whiteness of normal ink is achieved.
White triangles are those without conventional ink stirring means (stirring containers).
A black circle is a case where the ink stirring means (stirring container) of the present invention is mounted on a conventional printer.

In FIG. 5, a titanium oxide color material having a strong sedimentation is used for the ink, and after 10 days of rest, printing is performed on a transparent medium, and the L * value (whiteness) of the printed matter is measured.
The measurement conditions in FIG. 5 are as follows.
Printer used EPSON PX-G930
Media used: KOKUYO OHP film Ink composition for inkjet printers:
Titanium dioxide (average particle size 200nm) 10% by mass
Dispersant (styrene-acrylic acid copolymer) 2% by mass
1,2-hexanediol 5% by mass
Glycerin 10% by mass
Triethanolamine 0.9% by mass
BYK-348 (Big Chemie Japan Co., Ltd.) 0.5% by mass
Ultra pure water remaining
100% by mass

Evaluation method Solid ink is printed on a transparent medium with Duty 100% using a printer. After drying for 2 hours or more, the color is measured with a colorimeter (Spectrolino (GretagMacbeth)). The color measurement method is below the printed material.
This was done using EPSON PM-A700 with black paper with black solid printing on EPSON photo paper <Chrispia>. The L * value obtained by the color measurement is defined as the whiteness value, and the L * value is used as a reference value. Thereafter, the printer was left unused and the ink coloring material was allowed to settle, and after 10 days, printing and colorimetry were performed in the same manner. Then, the reduction rate of the L * value was obtained and evaluated for each ink consumption of the printed matter.
The results are shown in Table 1.

As shown in Table 1, in the case where there is no conventional stirring vessel, the maximum decrease rate of whiteness is reduced to 13%, whereas in the case where the stirring vessel of the reference example is mounted, as shown in the figure, It can be understood that the maximum decrease rate of the whiteness is 7%, and the deviation from the normal whiteness is small.

Next, in order to reduce the maximum reduction rate of the whiteness due to the difference in the concentration of the sedimentary substance in the ink jet printer that intermittently supplies the ink containing the sedimentary substance such as a coloring material via the ink supply pipe. As another method, another reference example that can be used in combination with the mounting of the above-described ink stirring means (stirring container) will be described in detail below.

Another reference example is shown below.
6 (a) and 6 (b), it is possible to shorten the time until the settled color material is uniformly dispersed and reaches the normal color material density after the rest period of the ink jet printer as another reference example. The principle of realizing the color material density leveling will be described.

FIG. 6B is the same configuration as that in FIG. 6A in which the ink tank (cassette) 1 and the head 2 are connected by the thin tubes 3 arranged horizontally, and is different from FIG. 6A. In FIG. 6 (b), the thin tubes are arranged horizontally, whereas the thin tubes are curved three times in a vertical direction (to the ground) (not necessarily three times). ).
The narrow tube in FIG. 6 (b) has a diameter of 2 mm, and the diameter of the helix (circular) is preferably 5 cm or less, preferably larger than the diameter of the narrow tube.

In FIG. 6 (b), the sediment 3a in FIG. 6 (b) is arranged so that the thin tube 3 is spirally rotated with respect to the ground. Sediment to close.
Further, the ink in a thin state of the color material is present on the upper part of the spiral tubule.
Therefore, in the thin tube, between the ink tank 1 and the head 2, an ink portion having a low color material concentration and a color material portion that has settled are alternately arranged.

In this state, when the ink jet printer is changed from a long rest state to an operating state and the ink is discharged from the ink head 2, the settled color material portion is first pushed out and stirred by the ink portion having a low color material concentration. Therefore, it is possible to reduce the amount of ink consumed until all of the settled color material melts into the ink and reaches the normal color material density after the rest period of the ink jet printer.

It will be described in detail with reference to the graph of FIG. 7 that the amount of ink consumed until all the settled color material melts into the ink and reaches the normal color material density can be reduced.
FIG. 7 is a graph for explaining the effect of another reference example.

In FIG. 7, the vertical axis represents the whiteness of the ink ejected from the head, and the whiteness in a normal use state is 0, and the whiteness reduction rate is shown.
The horizontal axis indicates the ink consumption until the whiteness of normal ink is achieved.
A white triangle is a conventional thin tube (tube) (flat channel) arranged in a flat shape, and the length of the thin tube is 240 cm.
The black circle is the case of the circular flow channel of the present invention, and the length of the tube is also 240 cm.

In FIG. 7, a titanium oxide color material having a strong sedimentation is used for the ink, and after 10 days of rest, printing is performed on a transparent medium, and the L * value (whiteness) of the printed matter is measured.
The measurement conditions in FIG. 7 are the same as those in the first embodiment of the present invention and are as follows.
Printer used EPSON PX-G930
Media used: KOKUYO OHP film Ink composition for inkjet printers:
Titanium dioxide (average particle size 200nm) 10% by mass
Dispersant (styrene-acrylic acid copolymer) 2% by mass
1,2-hexanediol 5% by mass
Glycerin 10% by mass
Triethanolamine 0.9% by mass
BYK-348 (Big Chemie Japan Co., Ltd.) 0.5% by mass
Ultra pure water remaining
100% by mass

Evaluation method Solid ink is printed on a transparent medium with Duty 100% using a printer. After drying for 2 hours or more, the color is measured with a colorimeter (Spectrolino (GretagMacbeth)). The color measurement method is below the printed material.
This was done using EPSON PM-A700 with black paper with black solid printing on EPSON photo paper <Chrispia>. The L * value obtained by the color measurement is defined as the whiteness value, and the L * value is used as a reference value. Thereafter, the printer was left unused and the ink coloring material was allowed to settle, and after 10 days, printing and colorimetry were performed in the same manner. Then, the reduction rate of the L * value was obtained and evaluated for each ink consumption of the printed matter.
The results are shown in Table 2.

As shown in Table 2, in the conventional flat flow path, the maximum decrease rate of whiteness is reduced to 30.4%, and about 7 ml of ink is wasted before the normal whiteness is restored. .
On the other hand, in the circular channel of another reference example, when the length of the thin tube is the same 240 cm, as shown in the figure, the maximum decrease rate of whiteness is 8.3%, It can be understood that there is little divergence from the ink and wasteful ink consumption is small.
As shown in FIG. 6 (b), the color material that settles in the narrow tube settles in a form that divides into the lower portions of the plurality of spiral portions and closes the narrow tube, and the ink is ejected from the head after the rest. At the same time, since the agitated so as to extrude the settled color material, it can be assumed that the whiteness close to that of normal ink is obtained from the time of resumption.

In addition, the thin tube is formed of a flexible material, and is fixed to the printer main body so as to be capable of weak vibration along with the movement of the head. By adopting a configuration in which the stirring action of the ink with respect to the precipitated color material is generated, it is possible to obtain the color material concentration of a normal ink in a shorter time.

Next, another reference example and its operation will be shown below.
As another form of another reference example, for example, in addition to the downward spiral tubule shown in FIG. 6B, for example, the following one shown in FIG. 8 may be used.
-As shown in Fig. 8 (a), the height difference in the vertical direction in the length direction of the capillary is greater than the inner diameter of the capillary.
A large number of continuous circular tubes.
A large number of continuous sine-shaped or corrugated tubules as shown in FIG. 8 (c), in which the vertical height difference in the length direction of the tubule is greater than the inner diameter of the tubule.
A capillary that is curved into a large number of continuous triangles or rectangles as shown in FIG. 8 (b) or (d), in which the vertical height difference in the length direction of the capillary is greater than the inner diameter of the capillary.
-Any combination of the above spiral or substantially circular shapes, sine shapes, corrugations, triangles or rectangles.
8 (a) to 8 (d), the ink tank (cassette) and the head are arranged horizontally, but when the ink jet printer is installed, the ink tank and the head are arranged with a height difference in the vertical direction. The ink supply pipe may be connected vertically or obliquely between the two as shown in FIG. 8 (e) or (f).
As described above, the configuration is not limited to the above-described configuration as long as the flow rate of flowing in the narrow tube can be supplied while providing a stirring effect by installing the resistance portion so as to change in the same narrow tube.

FIG. 8C shows a second embodiment of another reference example, which is the same as the state in which the ink tank (cassette) 1 and the head 2 in FIG. The configuration differs from FIG. 6 (b) in that in FIG. 8 (c) the thin tubes are horizontally arranged, whereas the thin tubes are curved in a wave shape in the vertical direction. .
The narrow tube in FIG. 8 (c) has a diameter of 2 mm, and the wavy top and bottom difference is 3 cm or less.

Next, the action of leveling the concentration difference of the sedimentation substance in a liquid supply system that intermittently supplies the liquid containing the sedimentation substance in another reference example via a thin tube will be described with reference to FIG. explain.

In FIG. 8 (c), as in FIG. 6 (b), since the thin tube 7 is arranged in a wavy shape with respect to the ground, the settled substance 7a closes the flow path of the thin tube at the lower part of the wavy portion of the thin tube. To settle.
In addition, the ink with a thin color material is present in the upper portion of the wavy tubule.
Accordingly, in FIG. 9A as well as in FIG. 6B, between the ink tank 1 and the head 2 not shown in the flow path of the thin tube, the ink portion having a low color material concentration and the settled color material portion alternate. It is in the state where it is arranged.

In this state, when the ink jet printer is put into an operating state from a long resting state and the ink is discharged from the ink head 2, the ink portion having a low color material density is initially shown in FIG.
As shown in (b) and FIG. 9 (c), the settled color material portion is pushed up.
When the ink is further discharged from this state, as shown in FIG. 9 (d), the color material portion diffuses and diffuses as it descends from the top of the wavy portion of the thin tube 7, thereby causing the color It is possible to level out the difference in concentration of the sedimentary substance that is the material portion in a short time.

In this way, since the pushed-up color material portion utilizes the diffusion when descending from the apex of the tubules arranged in a wave shape, the wave shape is inclined along the liquid flow direction. It is desirable that the descending direction is steeper than the ascending direction. (Even if the wavy rising part is steep, it helps to diffuse the colorant, but the rising part is not suitable because it works as a push-up resistance.)

The wavy flow path in the second embodiment consumes less ink than the circular flow path in the first embodiment until all of the settled color material melts into the ink and reaches a normal pigment concentration. What can be done will be described in detail with reference to the graph of FIG.
FIG. 10 is a graph for explaining the effect of another reference example.

In FIG. 10, as in FIG. 7, the vertical axis represents the whiteness of the ink ejected from the head, and the whiteness in a normal use state is set to 0, indicating the rate of decrease in whiteness.
The horizontal axis indicates the ink consumption until the whiteness of normal ink is achieved.
The open triangle is the same circular channel as in FIG. 5, and the length of the tube is 480 cm.
A black circle is the case of the wavy channel in the second embodiment, and the length of the tube is 210 cm because it is wavy.

In FIG. 10, similarly to FIG. 7, a titanium oxide color material that is heavily settled is used for the ink, and after 10 days of rest, printing is performed on a transparent medium, and the L * value (whiteness) of the printed matter is measured.
The measurement conditions in FIG. 10 are the same as in FIG.
Printer used EPSON PX-G930
Media used: KOKUYO OHP film Ink composition for inkjet printers:
Titanium dioxide (average particle size 200nm) 10% by mass
Dispersant (styrene-acrylic acid copolymer) 2% by mass
1,2-hexanediol 5% by mass
Glycerin 10% by mass
Triethanolamine 0.9% by mass
BYK-348 (Big Chemie Japan Co., Ltd.) 0.5% by mass
Ultra pure water remaining
100% by mass

Evaluation method Solid ink is printed on a transparent medium with Duty 100% using a printer. After drying for 2 hours or more, the color is measured with a colorimeter (Spectrolino (GretagMacbeth)). The color measurement method is below the printed material.
This was done using EPSON PM-A700 with black paper with black solid printing on EPSON photo paper <Chrispia>. The L * value obtained by the color measurement is defined as the whiteness value, and the L * value is used as a reference value. Thereafter, the printer was left unused and the ink coloring material was allowed to settle, and after 10 days, printing and colorimetry were performed in the same manner. Then, the reduction rate of the L * value was obtained and evaluated for each ink consumption of the printed matter.
The results are shown in Table 3.

As shown in Table 3, in the circular flow path, the maximum decrease rate of whiteness decreases to 8.3%, and about 22 ml of ink is wasted before the normal whiteness is restored.
On the other hand, in the wavy channel, when the length of the narrow tube is 210 cm, as shown in the figure, the maximum decrease rate of whiteness is 5.0%, and there is little deviation from normal whiteness, It can be understood that the wasteful ink consumption is as small as 13 ml.

In order to reduce the maximum decrease rate of the whiteness due to the difference in the concentration of the sedimentary substance in the ink jet printer that intermittently supplies the ink containing the sedimentary substance such as a coloring material via the ink supply pipe, FIG. The ink stirring means (stirring container) shown in FIG. 4 and the height difference with respect to the direction in which the liquid is supplied to the at least part of the ink supply pipe, which is larger than the inner diameter of the pipe. As a region having, it should be formed in a spiral shape or a circular shape ”or“ a width difference larger than the inner diameter of the ink supply tube to at least a part of the ink supply tube, and a height difference with respect to the direction of supplying the liquid as a center reference ” The combined use of “the region portion having a sign shape or wave shape” provides a synergistic effect that cannot be obtained alone.

  As described above, the applicant of the present invention smoothes out the concentration difference of the sedimentary substance in an ink jet printer that intermittently supplies ink containing a sedimentary substance such as a colorant via an ink supply pipe. Although various reference examples have been studied as an inkjet printer capable of this, as shown in the graphs of FIGS. 5, 7, and 10, it is still impossible to level out the concentration difference of the sedimentary substance in a short time. Was the current situation.

  An object (object) of the present invention is to equalize a concentration difference of the sedimentary substance in a liquid jet printer that intermittently supplies a liquid containing a sedimentary substance such as a coloring material via a liquid supply pipe in a shorter time. It is to realize a liquid jet printer that can be realized.

  The liquid jet printer of the present invention is a liquid jet printer including a stirring container having a liquid stirring means connected to a liquid tank and a liquid supply pipe to supply a liquid to a print head, and the liquid is provided in the stirring container. A liquid blocking means for blocking inflow of liquid from the supply pipe; and when the amount of liquid in the stirring container falls below a predetermined value, the liquid blocking means is opened and the liquid inside the stirring container is opened via the liquid supply pipe. And a liquid replenishing means for replenishing the liquid.

The agitation container is mounted on a carriage that reciprocates the print head, has a built-in agitation sphere that can move in the agitation container, and stirs the liquid sediment as the carriage reciprocates. And
The agitation container is arranged in the vicinity of a line head in which the print medium is arranged in a direction perpendicular to the scanning direction, and the agitation means in the agitation container is driven at least during a printing operation to agitate the liquid sediment. It is characterized by doing.
The liquid replenishing means is a suction pump provided in the stirring vessel or a pressure pump provided in a liquid tank.
-The capacity | capacitance of the said stirring container is larger than the liquid quantity in the said liquid supply pipe | tube.
The liquid is a white ink containing a settling colorant.
-The coloring material is titanium oxide.

  According to the present invention, the concentration difference of the sedimentary substance in a liquid jet printer that intermittently supplies a liquid containing a sedimentary substance such as a coloring material via a liquid supply pipe can be leveled in a shorter time. Is possible.

It is a figure which shows the structure of the inkjet printer provided with the ink stirring container and ink replenishing means of this invention. 6 is a graph for explaining that the amount of ink consumed until all of the color material settled in the present invention is melted into ink and reaches a normal color material concentration can be reduced. FIG. 6 is a diagram schematically illustrating a state in which a color material has settled in a conventional example in which an ink tank and a head 2 are connected by a thin tube (ink supply tube) disposed horizontally. It is a figure which shows the detailed example of the stirring container 4 of this invention. FIG. 6 is a diagram for explaining the principle of realizing the color material density leveling that can shorten the time until the settled color material reaches the normal color material density after the rest period of the inkjet printer in the present invention. It is a figure which shows embodiment of the ink supply pipe | tube of a reference example. It is a graph explaining that the consumed amount of ink can be reduced until all the settled color material is melted into ink and reaches a normal color material density. It is a figure which shows another embodiment of the ink supply pipe | tube of a reference example. It is a figure explaining the effect | action which equalizes the density | concentration difference of the sedimentation substance in the 2nd Embodiment of this invention in a short time. In a 2nd embodiment, it is a graph explaining that the amount of consumption of ink can be decreased until all the settled coloring materials are melted in ink and reach a normal pigment concentration. It is a figure which shows the arrangement | positioning relationship between an ink tank, a head, and an ink supply tube in the inkjet printing apparatus carrying the conventional ink supply mechanism.

In addition, the ink containing a sedimenting substance in the present invention refers to a liquid (ink) having a large specific gravity difference between a solvent and a color material as compared with a general color material ink. Specifically, the dispersion solvent (water has a specific gravity of 1
The specific gravity of carbon black or organic color material, which is a general color material, is about 1 to 1.3, while titanium oxide is 3.7 to 4.2. A liquid (ink) having a specific gravity difference of 1 or more between the solvent and the coloring material.
In the present invention, not only titanium oxide but also white color materials such as zinc, lead, barium, titanium, antimony and other oxides, sulfates and carbonates, and metallic color materials such as aluminum and aluminum alloys (an example) JP 2008-174712) can also be used.
In addition, although the ink of the present application has been described using water-based ink as an example, it can also be applied to ultraviolet curable ink. Further, the medium may be water, a solvent, or a polymerizable monomer as long as it contains a sedimenting substance.

When the ink of the present invention contains the white color material of the present invention, the content of the particles of the present invention (
The solid content) is preferably 5 to 20% by mass, more preferably 8 to 15% by mass, based on the total mass of the ink composition. When the content (solid content) of white particles exceeds 20% by mass,
Reliability such as clogging of the ink jet recording head may be impaired. On the other hand, 5% by mass
If it is less than 1, the whiteness tends to be insufficient. In order to improve dispersibility, the particle size of the colorant is preferably 2.0 μm or less, more preferably 0.2 μm or less.

The ink composition of the present invention contains a resin for fixing the color material of the present invention. As such resin,
Examples thereof include acrylic resins (for example, Almatex (manufactured by Mitsui Chemicals)) and urethane resins (for example, WBR-022U (manufactured by Taisei Fine Chemical Co., Ltd.)).
The content of these fixing resins is preferably 0.5 to 1 with respect to the total mass of the ink composition.
It is 0 mass%, More preferably, it is 0.5-3.0 mass%.

The ink composition of the present invention preferably contains at least one selected from alkanediols and glycol ethers. Alkanediols and glycol ethers
It is possible to increase the wettability of a recording surface such as a recording medium and improve the ink permeability.

Examples of alkanediol include 1,2-butanediol, 1,2-pentanediol, 1
1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol and the like are preferably 1,2-alkanediols having 4 to 8 carbon atoms. Of these, 1,2-hexanediol, 1,2-heptanediol, and 1,2-octanediol having 6 to 8 carbon atoms are more preferred because of their particularly high permeability to recording media.

As glycol ethers, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol Mention may be made of lower alkyl ethers of polyhydric alcohols such as monomethyl ether, triethylene glycol monobutyl ether and tripropylene glycol monomethyl ether. Among these, when triethylene glycol monobutyl ether is used, good recording quality can be obtained.

The content of at least one selected from these alkanediols and glycol ethers is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, based on the total mass of the ink composition.

The ink composition of the present invention preferably contains an acetylene glycol surfactant or a polysiloxane surfactant. Acetylene glycol surfactants or polysiloxane surfactants can increase the wettability of a recording surface such as a recording medium to increase the ink permeability.

Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3, 5-dimethyl-1-hexyne-3ol, 2,4-dimethyl-5-hexyne-3-
Examples include all. Moreover, a commercial item can also be utilized for acetylene glycol type-surfactant, for example, Orphine E1010, STG, Y (above, Nissin Chemical Co., Ltd.), Surfinol 104, 82, 465, 485, TG (above , Air Products
and Chemicals Inc. Manufactured).

Commercially available products can be used as the polysiloxane surfactant, such as BYK.
-347, BYK-348 (manufactured by Big Chemie Japan) and the like.

Furthermore, the ink composition of the present invention can also contain other surfactants such as an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant.
The content of the surfactant is preferably 0.01 to 5 with respect to the total mass of the ink composition.
It is mass%, More preferably, it is 0.1-0.5 mass%.

The ink composition of the present invention preferably contains a polyhydric alcohol. When the ink composition of the present invention is applied to an ink jet recording apparatus, the polyhydric alcohol can suppress ink drying and prevent ink clogging in the ink jet recording head portion.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol,
Examples include hexylene glycol, glycerin, trimethylol ethane, and trimethylol propane.

The content of the polyhydric alcohol is preferably 0.1 to the total mass of the ink composition.
It is 3.0 mass%, More preferably, it is 0.5-20 mass%.

The ink composition of the present invention contains water as a solvent. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltered water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be suppressed over a long period of time.

Furthermore, the ink composition of the present invention may be prepared by using a fixing agent such as a water-soluble rosin, an antifungal agent / preservative such as sodium benzoate, an antioxidant / ultraviolet absorber such as allophanates,
Additives such as chelating agents and oxygen absorbers can be contained. These additives are 1
One species can be used alone, and of course, two or more species can be used in combination.

An embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a schematic diagram showing a relationship between an ink tank and an ink supply pipe connecting a print head of an ink jet printer of the present invention.
In FIG. 1, 1 is an ink tank, 2 is a print head, 3 is an ink supply pipe, 4 is a stirring container (sub tank), and the stirring container (sub tank) is mounted together with the print head on a carriage that drives the print head. Yes.

  In the stirring container (sub tank) 4, an ink blocking means (shutoff valve) 6, an ink replenishing means (suction pump) 5, and a stirring means (stirring ball) 4-1 for blocking the supply of ink from the ink supply pipe are provided. 4-2 is arranged.

The ink replenishing means 5 draws out the ink in the ink supply pipe 3 at a stroke and stores it in the stirring container (sub tank) when the ink in the stirring container (sub tank) falls below a predetermined amount.
By sucking out the ink in the ink supply pipe 3 at a stretch, it becomes possible to transfer a precipitate such as titanium dioxide that has settled in the ink supply pipe to the stirring container (sub tank) together with the ink.
The ink shut-off means (shut-off valve) is normally closed, and is opened when the ink in the stirring container (sub tank) falls below a predetermined amount, and the ink in the ink supply pipe 3 is sucked out at a stroke and the stirring container ( It is closed after storing in the sub tank.
The colorant such as titanium dioxide accumulated in the stirring vessel (sub tank) is moved along the bottom of the stirring vessel by the stirring ball as the carriage moves to drive the print head. Therefore, it is possible to reduce the decrease in whiteness from the start of printing.

  In FIG. 1, the ink replenishing means 5 is arranged in the stirring container 4, but it can also be arranged in the ink tank 1 as an extrusion pump.

  Although it is possible to detect that the ink in the agitation container (sub tank) has fallen below a predetermined amount, which triggers the operation of the ink replenishing means 5, it is possible to count the ejection amount of ink droplets from the print head. Another method may be used to detect that the amount of ink in the stirring container (sub tank) has fallen below a predetermined amount. For example, a liquid amount detection sensor may be provided.

In FIG. 1, the print head is mounted on a carriage and driven at the time of printing. However, in the case of an inkjet printer having a line print head equal to the print width as a print head, Although it is arranged in the vicinity of the stirring vessel (sub tank), the stirring effect of the precipitate by the stirring sphere cannot be expected. Therefore, it is necessary to provide stirring means driven by a motor or the like in the stirring vessel (sub tank) at least during printing operation.
Even in the case of a printer in which the print head is mounted on a carriage, stirring means driven by a motor or the like instead of stirring by a stirring ball may be provided.

FIG. 2 is a graph for explaining the effect of the embodiment of the present invention.
In FIG. 2, the vertical axis represents the whiteness of the ink ejected from the head, and the whiteness in a normal use state is set to 0, and the whiteness reduction rate is shown.
The horizontal axis indicates the ink consumption until the whiteness of normal ink is achieved.

A white square is a conventional thin tube (tube) (flat channel) arranged in a flat shape, and the length of the ink channel is 240 cm (7.4 ml) without a sub tank.
White triangles are conventional thin tubes (tubes) (flat channels) arranged in a flat shape, with a sub-tank and an ink channel length of 240 cm (7.4 ml).
A black circle is a thin tube (tube) (flat channel) according to the present invention having a sub-tank and a suction pump provided in the sub-tank. The length of the ink channel is 240 cm (7 4 ml).

In FIG. 2, a titanium oxide color material having a strong sedimentation is used for the ink, and after 10 days of rest, printing is performed on a transparent medium, and the L * value (whiteness) of the printed matter is measured.
The measurement conditions in FIG. 2 are as follows.
Printer used EPSON PX-G930
Media used: KOKUYO OHP film Ink composition for inkjet printers:
Titanium dioxide (average particle size 200nm) 10% by mass
Dispersant (styrene-acrylic acid copolymer) 2% by mass
1,2-hexanediol 5% by mass
Glycerin 10% by mass
Triethanolamine 0.9% by mass
BYK-348 (Big Chemie Japan Co., Ltd.) 0.5% by mass
Ultra pure water remaining
100% by mass

Evaluation method Solid ink is printed on a transparent medium with Duty 100% using a printer. After drying for 2 hours or more, the color is measured with a colorimeter (Spectrolino (GretagMacbeth)). The color measurement method is below the printed material.
This was done using EPSON PM-A700 with black paper with black solid printing on EPSON photo paper <Chrispia>. The L * value obtained by the color measurement is defined as the whiteness value, and the L * value is used as a reference value. Thereafter, the printer was left unused and the ink coloring material was allowed to settle, and after 10 days, printing and colorimetry were performed in the same manner. Then, the reduction rate of the L * value was obtained and evaluated for each ink consumption of the printed matter.
The results are shown in Table 4.

As shown in Table 4, in the conventional white square, the maximum decrease rate of whiteness is reduced to 30.4%, and about 7 ml of ink is wasted before the normal whiteness is restored. The
Further, in the conventional white triangle, when the length of the narrow tube is the same 240 cm, as shown in the figure, the maximum decrease rate of whiteness is 8.3%, and the deviation from the normal whiteness is small, and the whiteness is white. Consumption of wasted ink is less than that of a square with a blank.
On the other hand, in the black circle of the present invention, in the case where the length of the narrow tube is the same 240 cm, as shown in the figure, the maximum decrease rate of the whiteness is almost zero, and there is little deviation from the normal whiteness, which is wasteful. It can be understood that the consumption of ink is almost gone.

In the present invention, in the stirring container (sub tank) 4 of FIG. 1, an ink blocking means (shutoff valve) 6 for blocking the supply of ink from the ink supply pipe, an ink replenishing means (suction pump) 5, and a stirring are provided. The means (stirring balls) 4-1 and 4-2 are described as having a configuration in which they are arranged as a main part, but they are combined with the ink supply tube configuration shown as a reference example in FIGS. 6 and 8. It is also possible to configure.
In addition, by making the capacity of the stirring container larger than the capacity of the ink supply pipe, even if ink has settled in the ink supply pipe when the ink supply pipe is shut off, the ink is supplied to the stirring container once by refilling the ink. This is preferable because non-uniformity of the ink components can be reduced. In particular, it is preferable that the amount of ink replenished in the stirring container with one ink replenishment is larger than the capacity of the ink supply pipe.
In the above embodiment, the present invention is embodied as an ink jet printer that prints ink from a print head as a liquid. However, any printer that prints by discharging liquid from a print head may be used. For example, a liquid crystal material or an organic EL material may be used. It is also possible to provide a printer that manufactures a display panel by discharging from a print head. Further, in addition to the liquid having the property that the liquid component settles, it is also effective in the case of a liquid in which the liquid component becomes non-uniform in a stationary state.

1: Ink tank (ink pack)
2: Head (printing head)
3: Supply pipe (narrow pipe)
4: Stirring container (sub tank)
4-1,4-2: Stirring ball 5: Pump 6: Ink blocking means (valve)

Claims (7)

A liquid jet printer comprising a stirring container connected with a liquid tank and a liquid supply pipe and having a liquid stirring means for supplying a liquid to a print head,
A liquid blocking means for blocking liquid inflow from the liquid supply pipe in the stirring vessel;
Liquid replenishing means for opening the liquid blocking means and replenishing the liquid into the stirring container via the liquid supply pipe when the amount of liquid in the stirring container falls below a predetermined value;
A liquid jet printer comprising:   The agitation container is mounted on a carriage that reciprocates a print head, has a built-in agitation sphere that is movable in the agitation container, and agitates liquid sediment as the carriage reciprocates. The liquid jet printer according to claim 1.   The stirring container is disposed in the vicinity of a line head in which a printing medium is disposed in a direction perpendicular to the scanning direction, and the stirring means in the stirring container is driven at least during a printing operation to stir the liquid sediment. The liquid jet printer according to claim 1.   4. The liquid jet printer according to claim 1, wherein the liquid replenishing means is a suction pump provided in the stirring container or a pressure feed pump provided in a liquid tank. 5. 5. The liquid jet printer according to claim 1, wherein a capacity of the stirring container is larger than a capacity in the liquid supply pipe.   The liquid jet printer according to claim 1, wherein the liquid is a white ink containing a settling color material. The liquid jet printer according to claim 6, wherein the color material is titanium oxide.

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