JP2010184424A - Inkjet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer capable of uniformizing a difference in concentration of the sedimentary substance in an ink jet printer using an ink with a liquid containing a sedimentary substance such as a pigment.
In an inkjet printer that reciprocates a carriage having a print head in a main scanning direction and moves a print medium in a direction perpendicular to the main scanning direction to record an image on the print medium, the carriage reciprocates. And at least one stirring ball (4-1, 4-2) that is movable together with the stirring means (4), and the stirring ball moves along with the movement of the carriage, and contains a precipitating substance. An ink jet printer that stirs ink.

[Selection] Figure 2

Description

  The present invention relates to an ink jet printer that reduces the supply of ink having a reduced density due to precipitation to a print head by installing an ink stirring means on the carriage.

FIG. 4 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. 4, 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, which is 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 14 connected to the pressure adjustment unit 12 mounted on the carriage 11 is flexibly bent along 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 (ink jet printer) shown in FIG. 4, a supply tube (capillary tube) is used to supply ink from an ink tank containing ink containing a color material such as 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 pigment ink (for example, white ink) settles, causing nonuniform printing density, ejection failure, and nozzle clogging. In particular, in the case of an inorganic pigment such as titanium oxide used as a pigment for white ink, there is a problem that the ink tends to settle during a period when the ink is not flowing (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 device does not operate for several hours, it is possible to prevent the occurrence of ejection failure due to the occurrence of precipitation in the ink supply cartridge installed in the ink jet device. The following are known. (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 on a recording medium by ink jetting ink that is cured by irradiation of active energy, the image recording unit having an ink jet head that discharges the ink onto the recording medium; An ink cartridge provided with 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, comprising: an agitation member driving unit disposed on the apparatus side and capable of operating the agitation 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 in an ink supply pipe disposed between the ink tank (cartridge) and the print head. In fact, no consideration has been given to the sediments precipitated in the process.
Moreover, in the thing of patent document 2, there existed a problem that the stirring apparatus became complicated and large, such as requiring the stirring member drive part which consists of a magnetic rotor as an ink stirring apparatus.

When the effect of precipitation of inorganic pigments such as titanium oxide used as the pigment is seen from the print result on the medium, a print with reduced whiteness at a low density, not the intended pigment density, will continue for a predetermined time. Therefore, the printing state is not preferable.
This decrease in whiteness was unfavorable, reaching 9.2% at the beginning of printing.

  The subject (object) of this invention is related with the inkjet printer which can equalize | homogenize the density | concentration difference of the said sedimentation substance in the inkjet printer which uses ink for the liquid containing sedimentation substances, such as a pigment.

  In order to solve the above problems, an ink jet printer according to the present invention reciprocates a carriage having a print head in the main scanning direction, and moves the print medium in a direction perpendicular to the main scan direction so that an image is printed on the print medium. An ink jet printer for recording, comprising: an agitation unit including at least one agitation sphere movable along with the reciprocation of the carriage, wherein the agitation sphere moves along with the movement of the carriage and includes an ink containing a precipitating substance Is agitated.

The stirring means is a sub-tank provided between the ink tank and the print head, and the stirring ball is movably mounted on the carriage.
Further, the agitation means is constituted by a movable agitation sphere built in an ink cartridge mounted on the carriage.
The ink has a specific gravity difference of 1 or more between the solvent and the pigment.

The stirring ball is made of a material having a specific gravity of 2.5 g / cm ³ or more.
The stirring sphere is made of glass or zirconia.
The liquid pigment may contain titanium oxide.

In addition, the ink containing a sedimenting substance in the present invention indicates a liquid (ink) having a large specific gravity difference between a solvent and a pigment as compared with a general pigment ink. Specifically, the specific gravity of carbon black or organic pigment, which is a general pigment, is about 1 to 1.3 with respect to the dispersion solvent (water has a specific gravity of 1 and organic solvent of 1 or less). 3.7 to 4.2, and indicates a liquid (ink) having a specific gravity difference of 1 or more between the solvent and the pigment.
In the present invention, not only titanium oxide but also white pigments such as oxides such as zinc, lead, barium, titanium and antimony, sulfates and carbonates, and metallic pigments such as aluminum and aluminum alloys (specially as an example) Kai 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.

  In the ink of the present invention, when it is contained as the white pigment of the present invention, the content (solid content) of the particles of the present invention is preferably 5 to 20% by mass, more preferably based on the total mass of the ink composition. Is 8 to 15% by mass. When the content (solid content) of the white particles exceeds 20% by mass, reliability such as clogging of the ink jet recording head may be impaired. On the other hand, when it is less than 5% by mass, 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 pigment of the present invention. Examples of such resins 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 10% by mass and more preferably 0.5 to 3.0% by mass with respect to the total mass of the ink composition.

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

  Examples of the alkanediol include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 2-Alkanediol is preferred. 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.

  The glycol ethers include 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-hexyn-3-ol, 2,4-dimethyl-5-hexyn-3-ol and the like can be mentioned. 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.).

  Commercially available products can be used as the polysiloxane surfactant, and examples thereof include BYK-347, BYK-348 (manufactured by BYK Japan).

  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% by mass and more preferably 0.1 to 0.5% by mass with respect to the total mass of the ink composition.

  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, hexylene glycol, glycerin, and trimethylolethane. And trimethylolpropane.

  The content of the polyhydric alcohol is preferably 0.1 to 3.0% by mass, more preferably 0.5 to 20% by mass with respect to the total mass of the ink composition.

  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.

  In addition, the ink composition of the present invention may contain a fixing agent such as a water-soluble rosin, an antifungal agent / preservative such as sodium benzoate, an antioxidant / ultraviolet absorber such as allophanates, a chelating agent, if necessary. Additives such as oxygen absorbers can be included. These additives can be used alone or in combination of two or more.

  According to the present invention, in order to solve the above-described problems, the ink jet printer of the present invention stirs ink by agitating balls of the agitating means mounted on the carriage by the reciprocating movement of the carriage. The pigment that has settled later is uniformly mixed, and in the case of white ink, it is possible to reduce the decrease in whiteness in the printing result on the medium.

1 is an external view showing an ink jet printer equipped with an ink supply mechanism of the present invention, showing a print mechanism of the ink jet printer (a relationship between a print head mounted on a carriage and an ink stirring means (sub tank)). It is a figure which shows the detailed example of the stirring means (stirring container) 4 of this invention. It is a table | surface for demonstrating the stirring effect (prevention of a fall of whiteness) at the time of the printing after the rest period of an inkjet printer by this invention. 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.

FIG. 1 is an external view showing an ink jet printer equipped with an ink supply mechanism of the present invention and showing a print mechanism of the ink jet printer (relationship between a print head mounted on a carriage and an ink stirring means (sub tank)). .
In FIG. 1, an ink jet printing apparatus 1 includes a carriage 11 provided inside a printing mechanism and mounted with a print head (not shown), and ink supplied to the print head mounted on the carriage 11 via an ink supply tube 14. An ink tank 15 to be stored, a carriage drive belt 17 for driving the carriage 11 on which the print head is mounted along the carriage guide 16, a carriage drive motor 18 for driving the carriage drive belt 17, and a sheet for transporting the printing paper to the printing position. The printing paper conveyance guide unit 19 is included.

  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 is mounted moves to a predetermined print position along the carriage guide 16. Printing is performed on the printing paper conveyed from the printing paper conveyance guide unit 19 by reciprocating.

In FIG. 1, an ink agitation means (subtank) 4, which is a characteristic part of the present invention, is installed (fixed) in the carriage 11 along the reciprocating direction of the carriage 11.
The ink agitation means 4 is, for example, a laterally long container (sub tank) in which the input and output ports are connected to the ink supply path, and the agitation is movable inside the container fixed to the carriage 11. Contains one or more spheres.
The ink in the sub-tank of the agitation unit 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 means (sub tank) 4 in FIG. 1 will be described with reference to FIG.
In FIG. 2, reference numeral 4 denotes a sub tank (stirring means) disposed 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). Two 4-2s (not necessarily two) are built in to be movable.
The stirring sphere is preferably moved along the bottom of the sub-tank because ink precipitates accumulate in the lower part of the sub-tank.

  The table of FIG. 3 is a table for explaining the stirring effect by mounting the ink stirring means (stirring container) of the present invention.

In the table of FIG. 3, the titanium oxide pigment 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 the table of FIG. 3 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 was carried out by placing a black sheet of black solid printed on EPSON photographic paper <Krispia> using EPSON PM-A700 under the printed matter. 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, the ink pigment was allowed to settle, and printing and colorimetry were similarly performed after 10 days. Then, the reduction rate of the L * value was obtained and evaluated for each ink consumption of the printed matter.
According to the evaluation results,

  As shown in Table 1, in the case without the conventional sub-tank (stirring means) (that is, without the stirring sphere), the maximum decrease rate of the whiteness is decreased to 9.2%. In the case where a sub-tank with a built-in stirring ball is mounted, the maximum decrease rate of whiteness is 1.3% to 8.4% as shown in the figure.

  Next, it will be described in detail below that the maximum decrease rate of the whiteness changes according to the material (specific gravity) of the stirring sphere when the sub-tank including the stirring sphere is mounted on the carriage of the present application.

First, the specific gravity of the stirring balls For 1.4 g / cm ³ of POM (polyacetal), the maximum rate of decrease in whiteness was 8.4%.
Further, in the case of Teflon (registered trademark) having a specific gravity of the stirring sphere of 2.1 g / cm ³ , the maximum decrease rate of whiteness was 6.6%.

Further, in the case of a glass having a specific gravity of a stirring sphere of 2.5 g / cm ³ , the maximum decrease rate of whiteness was 1.3%.
In the case of zirconia having a specific gravity of a stirring sphere of 6 g / cm ³ , the maximum decrease rate of whiteness was 3%.

From this, it can be understood that when the stirring ball is a heavy stirring ball having a specific gravity of 2.5 g / cm ³ or more, the stirring effect is further enhanced by the action of scraping the sedimentary substance precipitated on the bottom of the sub tank.
Further, in the case of zirconia having a specific gravity of 6 g / cm ³ for the stirring sphere, the maximum decrease rate of whiteness is 3% as compared with the case of glass, and the stirring effect is slightly reduced. It can be understood that this is not a tendency.

  In the above description, the stirrer is described as stirring the precipitating substance in the sub tank provided between the ink tank and the print head. However, the ink jet of the type in which the ink cartridge is directly attached to the carriage. In the printer, at least one stirring ball may be built in the ink cartridge without providing the sub tank.

  In the above description, an example of an ink jet printer using pigment ink is described. However, the present invention does not necessarily need to be a pigment of ink as a sedimentary substance, and a liquid containing a sedimentary substance is placed in a tube. Needless to say, the present invention can be applied to other uses as long as the liquid supply system supplies intermittently through the liquid supply system.

1: Ink tank 2: Head (printing head)
3, 7, 14: Ink supply tube (narrow tube)
3a, 7a: Precipitating substances (pigments)
4: Stirring means (sub tank)
4-1, 4-2: Stir ball

Claims (7)

In an inkjet printer that reciprocates a carriage mounted with a print head in the main scanning direction and moves the print medium in a direction perpendicular to the main scan direction to record an image on the print medium.
Comprising stirring means incorporating at least one stirring ball movable with reciprocation of the carriage;
An ink jet printer, wherein the stirring ball moves with the movement of the carriage to stir ink containing a precipitating substance.   2. The ink jet printer according to claim 1, wherein the stirring means is a sub tank provided between an ink tank and a print head, and the stirring ball is movably mounted on the carriage.   2. The ink jet printer according to claim 1, wherein the agitation unit is constituted by a movable agitation ball built in an ink cartridge mounted on the carriage.   The ink jet printer according to any one of claims 1 to 3, wherein the ink has a specific gravity difference of 1 or more between a solvent and a pigment. The ink jet printer according to claim 1, wherein the stirring sphere is made of a material having a specific gravity of 2.5 g / cm ³ or more.   The inkjet printer according to claim 1, wherein the stirring sphere is made of glass or zirconia.   The inkjet printer according to claim 1, wherein the liquid pigment includes titanium oxide.

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