JP2013059892A - Inkjet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus in which stable ejection is allowed without causing a filter clogging even in a long term use.SOLUTION: An ink supplying unit for supplying ink containing at least water, a pigment and a water soluble organic solvent, includes a filter formed of a stainless steel in which Al and Si occupy 5% or less in total, in a composition of a surface element of the filter. The pigment of the ink is prepared by dispersing the pigment with a dispersant that includes an ethylene oxide chain as a hydrophilic group in the structure of the dispersant and is contained in the ink by an amount corresponding to 5.0-40.0 wt% relative to the pigment.

Description

  The present invention relates to an inkjet head for inkjet recording, an inkjet recording apparatus, and particularly, a so-called durable inkjet head that has excellent ejection ability even when using a pigment ink and does not clog even when used for a long period of time, and The present invention relates to an inkjet recording apparatus including the same.

Inkjet printers have recently gained rapid popularity as digital signal output devices because they have advantages such as low noise, low running cost, and easy color printing.
A dye-based ink in which various water-soluble dyes are dissolved in water or a mixture of water and an organic solvent is used, but the dye-based ink is excellent in color tone sharpness but inferior in light resistance. Inks using pigments that have drawbacks and are superior to those of dyes in terms of water resistance and weather resistance are used.

However, unlike dye ink, pigment ink contains many pigment particles with unstable dispersion in the ink, causing aggregates of pigment particles, clogging of nozzles, and hindering normal ejection. It was sometimes done. In order to solve such a problem, it has been proposed to provide a filter between the ink supply unit and the ink discharge unit.
However, in an ink jet printer, there is a great demand for higher image quality and higher speed, and in order to achieve this, there is a tendency for the diameter of the nozzle that is the ink flying means to be reduced.
For this reason, the diameter of the filter is also considerably smaller than the conventional filter diameter.
As a result, the filter is likely to be clogged, the pressure loss when the ink reaches the nozzle becomes large, and the problem remains that the ejection becomes unstable.

On the other hand, various proposals have been made regarding filters in order to ensure long-term reliability.
For example, Japanese Patent Application Laid-Open No. 9-187955 of Patent Document 1 uses a method of using a sintered nonwoven fabric made of metal fibers, and Japanese Patent Application Laid-Open No. 9-109411 of Patent Document 2 is formed by twilling metal fibers. As a method of using a filter, Japanese Patent Application Laid-Open No. 2005-324444 of Patent Document 3 proposes a method of using a filter formed by penetrating many fine holes through a flat metal plate.

  On the other hand, as a device on the ink side, for example, Japanese Patent Application Laid-Open No. 2006-070105 of Patent Document 4 describes that the dispersion stability of a pigment is improved by adding aminopropanediol to the ink. Japanese Patent Application Laid-Open No. 2004-204075 describes that a preservative having a specific structure is added to prevent the generation of foreign matters in the ink. Japanese Patent Application Laid-Open No. 2009-173829 of Japanese Patent Application Laid-Open No. An ink that does not cause clogging of a filter by defining the type of organic solvent contained and the content of a water-soluble resin is disclosed.

  However, there is still a problem that the problem that the filter clogs with time due to long-term use and the pressure loss increases is not solved.

For example, in Japanese Patent Application Laid-Open No. 2005-288810 of Patent Document 7, the filter life can be extended, high image quality can be maintained over a long period of time, and the filter is downsized to arrange the filter in a multi-nozzle, multi-color, high-density head. For the purpose of providing an ink jet printer that makes it easy to perform, an ink jet printer provided with a sintered filter in which stainless steel fibers are sintered with respect to dye ink, and a twill mat filter in which stainless fibers are twilled into pigment ink is provided. Is disclosed.
The present invention is similar to the present invention in that a filter is certainly provided to achieve long-term discharge stability.
However, in Patent Document 7, even if it is a pigment ink, if it is a twill woven filter, it is said that stable ejection can be achieved without clogging in the long term. According to the property evaluation experiment, it was found that even if a twill woven filter was used, sufficient discharge could not be achieved.
In addition, with the ejection stability verified in the embodiment of the above publication, it has only been confirmed that the pressure loss does not increase with respect to the ink flow amount of 512 ch × 10 kHz × 10 pl × 300 sec≈200 g. We believe that this is an inadequate level for considering the filter life for printer life.
In addition, the twilled woven filter has a uniform pore shape and can be filtered with high accuracy. However, the porosity is low, so the initial pressure loss is high, and the rigidity and cost of the filter itself are reduced. Since there are many disadvantages compared with the binding filter, a method that can ensure good liquid permeability regardless of the filter shape has been desired.
Since there has never been a discussion about the surface composition of the filter and the ink corresponding to it, as described above, ink jet recording capable of stable ejection without causing clogging for an extremely long time regardless of the filter shape. The problem that the device is not obtained has not been solved.

  An object of the present invention is to provide an ink jet recording apparatus capable of stable ejection without clogging a filter even when used for a long period of time.

There has been no discussion about the surface composition of the filter and the ink corresponding thereto, and as described above, there is an inkjet recording apparatus capable of stable ejection without causing clogging for an extremely long time regardless of the filter shape. In the process of diligently studying to improve the point that the problem of not being able to be solved, the present inventors cannot stably discharge for a long time, i.e., the filter is clogged during long-term use. It was discovered that the filter itself is clogging in a stainless steel filter that has excellent long-term durability.
For this reason, in order to ensure long-term reliability, both an appropriate filter and an appropriate ink are required. Therefore, efforts were made to improve the surface condition of the stainless steel filter, particularly the composition state of the surface. The filter has been completed.
In addition, it is essential that one of the inks does not contain a material that sticks to the filter, and it is essential that the pigment in the ink has a very stable dispersion. Is optimal for surfactant-dispersed pigments, especially those that use a surfactant with an ethylene oxide chain as a hydrophilic group as a dispersant, because it is easy to attract water molecules, making it easier to obtain stable dispersion. Furthermore, in order to achieve the dispersion stability required by the present invention, it was determined that the addition amount of 5.0 to 40.0 wt% with respect to the pigment was essential, and the ink in the present invention was completed. It came.
Thus, the above-mentioned problems are solved by the following “ink supply unit”, “inkjet recording apparatus”, “inkjet recording method”, “inkjet recording ink”, and “inkjet recorded matter”. This is solved by the present invention including:
(1) “An ink supply unit that supplies ink containing at least water, a pigment, and a water-soluble organic solvent, the ink supply unit including a stainless steel filter, and the filter has a surface element composition of Al, Si Is a pigment in which the pigment of the ink is dispersed by a dispersant, and the dispersant has an ethylene oxide chain as a hydrophilic group in the structure, An ink supply unit comprising an amount corresponding to 5.0 to 40.0 wt% ”.
(2) “Ink supply unit according to item (1), wherein the dispersant is a nonionic surfactant”.
(3) “The ink supply unit according to item (1) or (2), wherein the surfactant has a structure represented by the following general formula (1)”.

（式中、Ｒは炭素数１〜２０のアルキル基、アリル基またはアラルキル基を表し、ｌは０〜７の整数を表し、ｎは２０〜２００の整数を表す。）

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, an allyl group, or an aralkyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200.)

(4) “The ink supply unit according to any one of (1) to (3) above, wherein the stainless steel constituting the filter is SUS316 or SUS316L”.
(5) “The ink supply unit according to any one of items (1) to (4), wherein the filter is a sintered filter in which stainless steel fibers are laminated in a felt shape and sintered”.
(6) The ink supply unit according to any one of (1) to (5), wherein the filter is a twill woven filter formed by twilling a stainless fiber.
(7) “Inkjet recording apparatus including the ink supply unit according to any one of (1) to (6)”.
(8) “A plurality of pressurized liquid chambers, nozzles having a pore diameter of 35 μm or less communicating with the pressurized liquid chambers and an ink supply path, electric pressure converting means or electrothermal converting means for discharging ink, filters and ink for generating negative pressure The inkjet recording apparatus according to item (7) having a tank.
(9) “An ink jet recording method comprising forming an image on a recording medium by continuously ejecting ink droplets using the ink jet recording apparatus according to item (7) or (8)”.
(10) “An ink recorded matter comprising an image formed by the ink jet recording method according to item (9)”.
The present invention also includes “inkjet recording ink” as described in the following items (11) to (13).
(11) “Ink that contains at least water, a pigment, and a water-soluble organic solvent, and is supplied to an ink supply unit for inkjet recording, wherein the pigment is dispersed by a dispersant, and the dispersant has a structure. It has an ethylene oxide chain as a hydrophilic group, and is contained in an amount corresponding to 5.0 to 40.0 wt% with respect to the pigment. The ink supply unit includes a stainless steel filter. An ink supply unit characterized in that the proportion of Al and Si in the composition is 5% or less in total.
(12) “Ink for inkjet recording according to item (11), wherein the dispersant is a nonionic surfactant”.
(13) “Ink for inkjet recording according to item (11) or (12), wherein the surfactant has a structure represented by the following general formula (1)”.

  As will be well understood from the following detailed and specific description, according to the present invention, the "ink supply unit", "stable discharge can be performed without clogging for a very long time regardless of the shape of the filter," The extremely excellent effect of providing an “inkjet recording apparatus”, “inkjet recording method”, “inkjet recording ink” and “inkjet recording product” is exhibited.

It is an element enlarged view of an ink jet head to which the present invention is applied. It is a principal part expanded sectional view of the direction between channels of the inkjet head to which this invention is applied. It is a perspective exploded block diagram which shows an inkjet head part periphery structure. It is a perspective exploded view which shows the structural example of a subtank. It is a schematic explanatory drawing which shows an example of the inkjet recording device of this invention. It is a schematic explanatory drawing which shows an example of the internal structure of the inkjet recording device of FIG. It is a schematic plan view which shows the internal structure of the inkjet recording device of FIG.

The present invention will be described in detail below.
As described above, the present invention relates to a combination of “the specific ink supply unit” and “specific ink”, that is, an ink supply unit that supplies ink containing at least water, a pigment, and a water-soluble organic solvent. The ink supply unit includes a stainless steel filter, and the filter has a surface element composition in which the proportion of Al and Si is 5% or less in total, and the pigment of the ink is a dispersant. An ink having an ethylene oxide chain as a hydrophilic group in the structure and contained in an amount corresponding to 5.0 to 40.0 wt% with respect to the pigment. A supply unit is provided, but in addition to the background of the present invention in advance, the filter is based on the elemental composition of its surface. l, The total proportion of Si must be 5% or less, and the stainless steel filter is made of very fine stainless steel fine wires. Silica or alumina powder is often used as an agent.
For this reason, silica and alumina may remain on the filter surface, and the remaining silica and alumina deteriorate the ink liquid permeability to the filter for the following reasons.
1. Since unevenness is given to the fiber of the filter, the surface property becomes rough and the flow of ink is disturbed.
2. Since silica has a property of attracting water, when the aqueous pigment ink passes, it attracts the pigment together with water, and as a result, aggregation proceeds with the portion as a nucleus.
3. Alumina easily adsorbs the surfactant, and in the case of the pigment dispersed in the active agent, the aggregation of the pigment easily occurs.
For the above reasons, the filter is gradually clogged with long-term use unless the presence of silica and alumina on the filter surface is kept below a certain value after using a dispersion-stable ink. The present invention addresses these issues.

[Inkjet ink]
The composition of the ink in the present invention includes, as described above, a pigment, a dispersant (surfactant) having an ethylene oxide chain, water, a water-soluble organic solvent, a penetrant, an antifoaming agent, a pH adjuster, Other components such as antiseptic and antifungal agents and rust preventives may be included. Hereinafter, these components will be described in order.

(Pigment)
The main role of the pigment is to color the ink and improve the image density. The addition amount is preferably 0.1 wt% or more and 50.0 wt% or less, more preferably 0.1 wt% or more and 20.0 wt% or less, and further preferably 3.0 wt% or more and 15.0 wt% or less.
The 50% average particle size (D ₅₀ ) of the pigment is preferably 10 to ₅₀₀ nm or less, and more preferably 50 to 200 nm or less. Here, the 50% average particle diameter of the pigment indicates the value of D ₅₀ measured by a dynamic light scattering method using Microtrac UPA manufactured by Nikkiso Co., Ltd. in an environment of 23 ° C. and 55% RH.

The pigment to be used is not particularly limited as long as the above characteristics are satisfied, and can be appropriately selected according to the purpose.
For example, any of an inorganic pigment and an organic pigment may be used. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, metal powder, and carbon black. Among these, carbon black is preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

Examples of the organic pigment include azo pigments, azomethine pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable.
Examples of the azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments.
Examples of the polycyclic pigment include a phthalocyanine pigment, a perylene pigment, a perinone pigment, an anthraquinone pigment, a quinacridone pigment, a dioxazine pigment, an indigo pigment, a thioindigo pigment, an isoindolinone pigment, a quinofullerone pigment, and a rhodamine B lake pigment. Is mentioned.
Examples of the dye chelates include basic dye chelates and acidic dye chelates.

Examples of black materials include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, copper, iron (CI pigment black 11), titanium oxide, and the like. And organic pigments such as aniline black (CI Pigment Black 1).
As the carbon black, a furnace method, a carbon black produced by the channel method, primary particle diameter of, 15Nm～40nm, specific surface area by BET ^{method, 50m 2 / g~300m 2 / g} , DBP oil absorption amount 40ml / 100 g to 150 ml / 100 g, those having a volatile content of 0.5% to 10% and a pH value of 2 to 9 are preferred.
As the carbon black, commercially available products can be used. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (all manufactured by Mitsubishi Chemical Corporation); Raven700, 5750, 5250, 5000, 3500, 1255 (all manufactured by Columbia); Regal400R, 330R, 660R, Mogu L, Monarch700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (all manufactured by Cabot); Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4A, and 4 (all manufactured by Degussa).

  There is no restriction | limiting in particular as a pigment which can be used for yellow ink as the thing for said colors, According to the objective, it can select suitably, for example, C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 2, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 75, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 174, C.I. I. Pigment yellow 180, and the like.

  The pigment that can be used in the magenta ink is not particularly limited and may be appropriately selected depending on the intended purpose. I. Pigment red 5, C.I. I. Pigment red 7, C.I. I. Pigment red 12, C.I. I. Pigment red 48 (Ca), C.I. I. Pigment red 48 (Mn), C.I. I. Pigment red 57 (Ca), C.I. I. Pigment red 57: 1, C.I. I. Pigment red 112, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 146, C.I. I. Pigment red 168, C.I. I. Pigment red 176, C.I. I. Pigment red 184, C.I. I. Pigment red 185, C.I. I. Pigment red 202, pigment violet 19, and the like.

  The pigment that can be used in the cyan ink is not particularly limited and may be appropriately selected depending on the purpose. I. Pigment blue 1, C.I. I. Pigment blue 2, C.I. I. Pigment blue 3, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15:34, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. Pigment blue 60, C.I. I. Pigment blue 63, C.I. I. Pigment blue 66; C.I. I. Bat Blue 4, C.I. I. Bat Blue 60 and the like.

The pigment is added to the ink as a pigment dispersion in which the pigment is dispersed in an aqueous medium.
In this case, the pigment dispersion contains at least a pigment, water, and a dispersant described later, and is added as a surfactant-dispersed dispersion in which the pigment is dispersed by the contained dispersant.
The surfactant-type pigment dispersion may further contain other components such as a water-soluble resin and a preservative as necessary.

The surfactant-dispersed pigment is dispersed in an aqueous medium and used as a pigment dispersion.
The dispersion includes the pigment, a dispersant described later, water, and various additives as necessary. A bead mill, for example, Dino Mill KDL type (manufactured by Shinmaru Enterprises Co., Ltd.), Agitator Mill LMZ (Ashizawa Finetech Co., Ltd.) ), SC mill (Mitsui Mining Co., Ltd.) and the like, and further, after bead mill dispersion, beadless mill, for example, high shear force type CLEARS5 (M Technique Co., Ltd.), Cavitron CD1010 ( Eurotech Co., Ltd.), module DR2000 (Shinmaru Enterprises Co., Ltd.), thin film swivel type T.C. K. It can be obtained by dispersing with a film mix (manufactured by Special Machine Industries Co., Ltd.), an ultra-high pressure collision type artemizer (manufactured by Sugino Machine Co., Ltd.), a nanomizer (manufactured by Yoshiyama Kikai Kogyo Co., Ltd.), or the like.
As beads used in the bead mill, ceramic beads are usually preferable, and zirconia balls are generally used. The bead diameter is preferably 0.05 mm or less, and more preferably 0.03 mm or less.
In the pre-dispersion step, pretreatment of coarse particles with a homogenizer or the like can further sharpen the particle size distribution, leading to improvements in image density and ejection stability.

(Dispersant)
The main role of the dispersant is to stably disperse the pigment in the aqueous medium.
The addition amount is at least 5.0 to 40.0 wt% with respect to the pigment, and 10.0 to 30.0 wt% is preferable from the viewpoint of stable dispersion.
If it is less than 5.0 wt%, the dispersion stability of the pigment is inferior, and the pigment tends to aggregate. If it exceeds 40.0 wt%, foaming is likely to occur, and clogging due to bubbles tends to occur.

As the dispersant, those containing an ethylene oxide chain as a hydrophilic group are particularly preferably used as described above. The dispersant used in the present invention can be used without particular limitation as long as it satisfies the above conditions, but either an anionic surfactant or a nonionic surfactant having an HLB value of 12 to 20 is suitable. .
The HLB used here is an abbreviation for Hydrophile-Lipophile Balance as commonly used by those skilled in the art, and is a value representing the degree of affinity of a surfactant for water and oil.
In general, various methods such as the Atlas method, the Griffin method, the Davis method, and the Kawakami method are known as methods for calculating the HLB, and there are some differences depending on the method.
The HLB of the anionic surfactant shown in the present invention is calculated by the Griffin equation represented by the following equation.
HLB value = 20 × (molecular weight of hydrophilic group part) / (molecular weight of surfactant)

Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, polyoxyethylene polycyclic phenyl ether sulfate ester salt (for example, NH ₄ , Na, etc.), polyoxyethylene alkyl ether sulfate salt, and the like. Examples of the nonionic surfactant having an HLB value of 12 to 20 include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene polycyclic phenyl ether, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene alkylphenyl. Examples include ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, and the like.
Among these, the compound represented by the following general formula (1) is particularly desirable in order to exhibit good dispersion stability.

（式中、Ｒは炭素数１〜２０のアルキル基、アリル基またはアラルキル基を表し、ｌは０〜７の整数を表し、ｎは２０〜２００の整数を表す。）

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, an allyl group, or an aralkyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200.)

In addition to the dispersant, the ink in the present invention may contain other surfactant as required for the purpose of facilitating the penetration of the ink into the paper.
There are no particular limitations on such surfactants, and any of amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used, but the relationship between the dispersion stability of colorants and image quality From polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, ethylene oxide of acetylene alcohol Nonionic surfactants such as adducts are desirably used. Depending on the formulation, it is possible to use (or use alone) a fluorine-based surfactant or a silicone-based surfactant.

(Water-soluble organic solvent)
The water-soluble organic solvent improves ejection stability by providing a moisturizing effect, and the content in the inkjet ink is preferably 5 to 50% by mass, and preferably 10 to 40% by mass. The following is more preferable.
When the content is less than 25% by mass, sufficient moisture retention as an ink cannot be ensured, and the ejection stability is lowered regardless of the type of organic solvent to be contained and the solvent ratio.
On the other hand, if it exceeds 50% by mass, the viscosity of the ink jet ink becomes very high, and it may be difficult to eject with a general ink ejection device. In addition, the drying property on paper is inferior, and the character quality on plain paper may be lowered.

Examples of the water-soluble organic solvent include, but are not limited to, the following.
For example, ethylene glycol, diethylene glycol, 1,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerin 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl 1,2,4-butanetriol, polyhydric alcohols such as 1,2,3-butanetriol, petriol, ethylene Glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene Polyhydric alcohol alkyl ethers such as glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl- Nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone, amides such as formamide, N-methylformamide, N, N-dimethylformamide, monoethanolamine, Examples thereof include amines such as diethanolamine and triethylamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol, propylene carbonate, and ethylene carbonate. These water-soluble organic solvents can be used alone or in combination of two or more.

  Among these, the inclusion of 1,3-butanediol, diethylene glycol, triethylene glycol and / or glycerin provides an excellent effect in preventing discharge failure due to moisture evaporation.

(water)
The water used in the present invention is preferably purified water.

[Recording device, ink supply unit, filter]
The ink jet recording apparatus of the present invention has at least an ink discharge means (= head), and uses an electric pressure conversion means or an electrothermal conversion means as the discharge means.
In this head, a stainless steel filter is provided between the ink supply unit and the ink discharge unit, and the stainless steel at this time is preferably austenitic stainless steel, particularly SUS316 or SUS316L, because of its excellent corrosion resistance. .
In the filter according to the present invention, the proportion of Al and Si in the elemental composition existing on the surface is 5% or less in total, and a stainless steel filter is particularly preferable.

  The means for obtaining a filter in which Al and Si occupy 5% or less of the elemental composition on the surface used in the present invention is not particularly limited. An acid cleaning using an acid or the like, an alkali cleaning using a hydroxide or the like, an organic solvent cleaning, an ultrasonic cleaning, a passivation treatment, or an electropolishing treatment may be combined as necessary.

The ink jet recording apparatus of the present invention has at least an ink discharge means (= head), and uses an electric pressure conversion means or an electrothermal conversion means as the discharge means.
The head in the present invention is provided with a stainless steel filter between the ink supply part and the ink discharge part, and the stainless steel at this time is austenitic stainless steel, particularly SUS316 or SUS316L, which is excellent in corrosion resistance. This is desirable.
As described above, the filter used in the present invention is limited to those in which the proportion of Al and Si in the elemental composition on the surface is 5% or less, and the method used for measuring the surface elemental composition is not particularly limited, but X Measurement by a linear photoelectron spectrometer (XPS) is easy.

  The shape of the filter used in the present invention is not particularly limited, and any known filter can be used as long as it satisfies the conditions. A sintered filter obtained by laminating and sintering stainless steel fibers in a felt shape and It is desirable to use a twill woven filter formed by twilling stainless steel fibers because an inkjet recording apparatus having a longer discharge reliability can be obtained.

The preferable range of the filter diameter in the present invention will be described. The upper limit of the hole diameter of the filter to be used is preferably half or less of the nozzle diameter because it is possible to remove foreign substances that clog the nozzle. That is, it is preferably 17 μm or less, more preferably 15 μm or less, and still more preferably 12 μm or less.
Also, the lower limit of the pore size of the filter is preferably 1 μm or more, more preferably 3 μm or more. If the filter pore size is less than 1 μm, the filter life is shortened by supplementing the pigment that does not need to be removed. There is a risk.

  In addition, this head has a plurality of pressurized liquid chambers, a nozzle having a hole diameter of 35 μm or less communicating with the pressurized liquid chamber, an ink supply path, an ink discharge section comprising an electric pressure conversion means for discharging ink or an electrothermal conversion means, and an ink discharge It is preferable to have a configuration in which a filter is provided between an ink supply unit including an ink tank that generates a negative pressure in the unit.

  The hole diameter (= nozzle diameter) communicating with the pressurized liquid chamber is 35 μm or less, more preferably 30 μm or less, and further preferably 25 μm or less.

FIG. 1 and FIG. 2 show an example of the configuration of the ink ejection unit using the electric pressure conversion means.
FIG. 3 is an element enlarged view of the ejection part of the ink jet head to which the present invention is applied, and FIG. 4 is an enlarged cross-sectional view of the main part in the channel-to-channel direction of the ejection part of the head.
The ink jet head discharge section includes a frame (1) formed with a notch that is not shown and a common liquid chamber (1-2), a fluid resistance section (2-1), and a pressurized liquid chamber (2). -2) and the flow path plate (2) formed with the communication port (2-3) communicating with the nozzle (3-1), the nozzle plate forming the nozzle (3-1), and the convex portion ( 6-1), a diaphragm (6) having a diaphragm part (6-2) and an ink inlet (6-3), and a laminated piezoelectric element (5) joined to the diaphragm via an adhesive layer (7) And a base (4) to which the laminated piezoelectric element (5) is fixed. The base (4) is made of a barium titanate ceramic, and the laminated piezoelectric elements (5) are arranged in two rows and joined.
The laminated piezoelectric element (5) is composed of a lead zirconate titanate (PZT) piezoelectric layer (not shown) having a thickness of 10 to 50 μm / layer and a silver / palladium (AgPd) having a thickness of several μm / layer. The internal electrode layers (not shown) are alternately stacked. An internal electrode layer (not shown) is connected to an external electrode (not shown) at both ends.
The laminated piezoelectric element (5) is divided on comb teeth by half-cut dicing, and each one is used as a drive part (5-6) and a support part (5-7) (non-drive part).
The outside of the external electrode (not shown) is limited by machining such as notches so as to be divided by half-cut dicing, and these become a plurality of individual electrodes (not shown). The other is conductive without being divided by dicing, and becomes a common electrode (5-5).
An FPC (8) is soldered to an individual electrode (not shown) of the drive unit. Further, the common electrode (5-5) is provided with an electrode layer at the end of the laminated piezoelectric element and is wound around to join the Gnd electrode of the FPC (8). A driver IC (not shown) is mounted on the FPC (8), thereby controlling application of drive voltage to the drive unit (5-6).

The diaphragm (6) is joined to a thin film diaphragm portion (6-2) and a laminated piezoelectric element (5) which is a drive portion (5-6) formed at the center portion of the diaphragm portion (6-2). An island-shaped convex portion (island portion) (6-1), a thick film portion including a beam joined to a support portion (not shown), and an opening serving as an ink inflow port (6-3) are plated with Ni by electroforming. Two layers of films are formed. The diaphragm portion has a thickness of 3 μm and a width of 35 μm (one side).
The coupling between the island-shaped convex part (6-1) of the diaphragm (6) and the movable part (5-6) of the laminated piezoelectric element (5) and the diaphragm (5) and the frame (1) includes a gap material. The adhesive layer (7) is bonded by patterning.

The flow path plate (2) uses a silicon single crystal substrate, the engraving that becomes the fluid resistance portion (2-1), the pressurized liquid chamber (2-2), and the communication port ( The through hole to be 2-3) was patterned by an etching method.
The portion left by etching becomes the partition wall (2-4) of the pressurized liquid chamber (2-2). Further, in this head, a portion for narrowing the etching width was provided, and this was used as the fluid resistance portion (2-1).

The nozzle plate (3) is formed of a metal material, for example, an Ni plating film by an electroforming method, and has a large number of nozzles (3-1) which are fine discharge ports for flying ink droplets. . The internal shape (inner side shape) of the nozzle (3-1) is formed in a horn shape (may be a substantially cylindrical shape or a substantially frustum shape). The diameter of the nozzle (3-1) is approximately 20 to 35 μm on the ink droplet outlet side. The nozzle pitch of each row was 150 dpi.
The ink ejection surface (nozzle surface side) of the nozzle plate (3) is provided with a water repellent treatment layer (not shown) subjected to a water repellent surface treatment (not shown). Ink physical properties such as PTFE-Ni eutectoid plating, electrodeposition coating of fluororesin, vapor-deposited fluororesin (for example, fluorinated pitch), baking after solvent application of silicon resin / fluorine resin, etc. A water-repellent treatment film selected according to the above is provided to stabilize the ink droplet shape and flight characteristics so that high-quality image quality can be obtained.
The frame (1) that forms the engraving that becomes the ink supply port and the common liquid chamber (1-2) (not shown) is made by resin molding.

In the ink jet head configured as described above, a drive waveform (pulse voltage of 10 to 50 V) is applied to the drive unit (5-6) in accordance with the recording signal, so that the drive unit (5-6) in the stacking direction is applied. Displacement occurs, the pressurized liquid chamber (2-2) is pressurized through the diaphragm (3), the pressure rises, and ink droplets are ejected from the nozzle (3-1).
Thereafter, the ink pressure in the pressurizing liquid chamber (2-2) decreases with the end of the ink droplet ejection, and the pressure in the pressurizing liquid chamber (2-2) depends on the inertia of the ink flow and the discharge process of the drive pulse. Negative pressure is generated and the process proceeds to the ink filling process. At this time, the ink supplied from the ink tank flows into the common liquid chamber (1-2), and flows from the common liquid chamber (1-2) through the ink inlet (6-3) to the fluid resistance portion (2-1). And the pressurized liquid chamber (2-2) is filled.
The fluid resistance portion (2-1) has an effect on the attenuation of the residual pressure vibration after ejection, but becomes resistant to refilling (refill) due to surface tension. By appropriately selecting the fluid resistance portion, it is possible to balance the attenuation of the residual pressure and the refill time, and to shorten the time (drive cycle) until the transition to the next ink droplet ejection operation.

  In the present invention, it is preferable that at least a part of the liquid chamber portion, the fluid resistance portion, the vibration plate, and the nozzle member of the ink discharge portion of the ink jet head is formed of a material containing at least one of silicon and nickel.

3 and 4 show an example of the ink supply unit (= sub tank).
FIG. 3 is an exploded perspective view for explaining an example of the structure around the inkjet head portion in the inkjet printer, in which (10) is a lever, (13) is a drive device for the lever (10), 20) is a carriage for mounting an ink jet head, (21) is an air release pin, (22) is a negative pressure pin, (23) is an elastic member, (30) is a sub tank for stocking ink in the carriage, (31 ) Is an air opening for adjusting the inside of the sub tank case to atmospheric pressure, (32) is a negative pressure lever, (40) is an inkjet head (hereinafter simply referred to as a head), and (50) is an ink cartridge. , (51) are connecting tubes for connecting the ink cartridge (50) and the sub tank (30) to supply ink to the sub tank (30).

  The filter of the present invention is provided at a portion connecting the sub tank (30) and the head (40) of FIG. For example, in an ink jet printer having a large amount of ink in a cartridge or an ink jet printer aiming at high image quality, when an ink cartridge is mounted in a carriage on which a head is mounted, the carriage (20) is Since image displacement may occur due to the influence of weight, for example, as shown in FIG. 3, an ink cartridge (50) is installed outside the carriage (20), and ink is temporarily put into the carriage (20). Some have a configuration with a sub-tank (30) for stocking.

  If the internal pressure of the sub tank (30) is positive, the ink leaks from the head (40) due to the weight of the ink in the sub tank (30), so the internal pressure of the sub tank (30) is negative. Must be set to Such pressure setting is important for the characteristics of ejecting ink from the head, but air may be mixed in from the ink cartridge (50) or the connecting tube (51), and the amount of air inside the sub tank (30). As the time increases with time, the internal pressure of the sub-tank (30) also changes, causing a problem that the quality of the image formed by ink deteriorates. For this reason, control is performed to periodically restore the air ratio and pressure setting inside the ink cartridge (50).

FIG. 4 is a perspective exploded configuration diagram for explaining the configuration example of the sub tank (30) shown in FIG. 3 in more detail.
The sub-tank (30) includes a case (33) which is constituted by a substantially rectangular top wall (39a), a bottom wall (39b) and three side walls (39c), and the other side wall is open, and the case A film (34) that covers the opening of (33), an elastic member (36) that presses the film (34) from the inside through a plate (35), and a film (34) that is pushed back from the outside. It is comprised from the negative pressure lever (32) which is a plate-shaped elastic member to urge. The elastic member (36) that presses the film (34) from the inside is set so as to press the film (34) with a stronger pressure than the negative pressure lever (32) that presses the film (34) from the outside. In the initial state, the film (34) is pushed outward. At this time, the balance of the pressing force between the negative pressure lever (32) and the inner elastic member (36) changes according to the fluctuation of the internal pressure of the sub tank (30), and the amount of ink in the sub tank (30) decreases. The film (34) is pushed back inward as the internal pressure changes.

  An air release port (31) provided in one of the side walls (39c) and an ink filling port (37) provided in the upper wall (39a) of the case (33) are elastic members (311), Sealed in a normal state by the close contact between the balls (312) and (372) pressed by (371), the elastic members (313) and (373) such as rubber, and the caps (314) and (374). ing. The ink filling port (37) is opened by the ink pressure flowing through the connecting tube (51) shown in FIG. 3, and the ink that flows in is supplied into the sub tank (30). Further, the air release port (31) is opened when the air release pin (21) provided on the carriage (20) shown in FIG. 3 is pressed and pushed in, and the internal pressure of the sub tank (30) can be adjusted.

  Further, the carriage (20) is provided with a negative pressure pin (22) for pushing the negative pressure lever (32) of the sub tank (30) from the outside, and the negative pressure lever (32) is provided inside the sub tank (30). The internal capacity of the sub tank (30) can be reduced by pushing the negative pressure pin (22) so as to be displaced. The elastic member (23) is provided so as to urge the negative pressure lever (32) and the negative pressure pin (22) in a direction away from each other, and normally the negative pressure lever (32) is caused by the action of the elastic member (23). ) And the negative pressure pin (22) are not touched.

  In the operation of the ink jet head configured as described above, the air release pin (21) is first operated to open the air release port (31), and the negative pressure pin (22) is operated to make negative. Ink is filled through the ink filling port (37) in a state where the internal volume of the sub tank (30) is reduced by pushing the pressure lever (32). The filled ink is detected at the upper part of the sub tank (30) by the full detection sensor (38), and the ink supply is controlled according to the detection result, thereby determining the air amount and the ink amount in the sub tank (30). Is done. Thereafter, the air release port (31) is closed and sealed, and then the pressure on the negative pressure lever (32) held in the pressed state is released. By such an operation, the inside of the sub tank (30) is controlled with a constant negative pressure, and stable ink ejection characteristics in the head (40) can be obtained.

Further, an example of the ink jet recording apparatus of the present invention will be described with reference to the drawings.
The ink jet recording apparatus shown in FIG. 5 has an apparatus main body (101), a paper feed tray (102) for loading paper mounted on the apparatus main body (101), and an image mounted on the apparatus main body (101). A paper discharge tray (103) for stocking the formed paper and an ink cartridge loading section (104) are provided.
On the upper surface of the ink cartridge loading section (104), an operation section (105) such as operation keys and a display is arranged. The ink cartridge loading section (104) has an openable / closable front cover (115) for attaching and detaching the ink cartridge (1 ′).

  In the apparatus main body (101), as shown in FIGS. 6 and 7, a guide rod (131), which is a guide member horizontally mounted on left and right side plates (not shown), and a stay (132) include a carriage ( 133) is slidably held in the main scanning direction, and is moved and scanned in the direction of the arrow in FIG. 7 by a main scanning motor (not shown).

The carriage (133) includes a recording head (134) including four inkjet recording heads that eject recording ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction and the ink droplet discharge direction is directed downward.
As an inkjet recording head constituting the recording head (134), a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a temperature change A shape memory alloy actuator using a metal phase change, an electrostatic actuator using an electrostatic force, or the like provided as an energy generating means for discharging recording ink can be used.
The carriage (133) is equipped with a sub tank (135) for each color for supplying ink of each color to the recording head (134). The sub-tank (135) is supplied with the recording ink of the present invention from the ink cartridge (1 ′) of the present invention loaded in the ink cartridge loading section (105) via a recording ink supply tube (not shown). To be replenished.

  On the other hand, as a paper feeding unit for feeding the paper (142) stacked on the paper stacking unit (pressure plate) (141) of the paper feed tray (103), 1 sheet (142) is fed from the paper stacking unit (141). A half-moon roller (sheet feeding roller 143) that separates and feeds the sheets one by one and a separation pad (144) made of a material having a large friction coefficient are provided opposite to the sheet feeding roller (143). The roller (143) is urged.

  A conveying belt (151) for electrostatically adsorbing and conveying the paper (142) as a conveying unit for conveying the paper (142) fed from the paper feeding unit below the recording head (134). A counter roller (152) for conveying the paper (142) sent from the paper supply unit via the guide (145) between the conveying belt (151) and a paper (substantially vertically upward) ( 142) and a leading guide roller 153 urged toward the conveying belt (151) by the holding member (154). (155) and a charging roller (156) which is a charging means for charging the surface of the conveyor belt (151).

  The conveyance belt (151) is an endless belt, is stretched between the conveyance roller (157) and the tension roller (158), and can circulate in the belt conveyance direction. On the back side of the conveyance belt (151), a guide member (161) is arranged corresponding to the printing area by the recording head (134). As a paper discharge unit for discharging the paper (142) recorded by the recording head (134), a separation claw (171) for separating the paper (142) from the transport belt (151), and paper discharge A roller (172) and a paper discharge roller (173) are provided, and a paper discharge tray (103) is arranged below the paper discharge roller (172).

  A double-sided paper feeding unit (181) is detachably attached to the back surface of the apparatus main body (101). The double-sided paper feeding unit (181) takes in the paper (142) returned by the reverse rotation of the transport belt (151), reverses it, and feeds it again between the counter roller (152) and the transport belt (151). . A manual paper feed unit (182) is provided on the upper surface of the double-sided paper feed unit (181).

In this ink jet recording apparatus, the sheet (142) is separated and fed one by one from the sheet feeding unit, and the sheet (142) fed substantially vertically upward is guided by the guide (145) and the transport belt (151). ) And the counter roller (152). Further, the leading end is guided by the conveying guide (153) and pressed against the conveying belt (151) by the leading end pressure roller (155), and the conveying direction is changed by about 90 °.
At this time, the conveyance belt (157) is charged by the charging roller (156), and the paper (142) is electrostatically adsorbed to the conveyance belt (151) and conveyed. Therefore, by driving the recording head (134) according to the image signal while moving the carriage (133), ink droplets are ejected onto the stopped sheet (142) to record one line, and the sheet ( 142), the next line is recorded after a predetermined amount is conveyed. Upon receiving a recording end signal or a signal that the rear end of the paper (142) has reached the recording area, the recording operation is finished and the paper (142) is discharged to the paper discharge tray (103).
When the recording ink remaining amount near end in the sub tank (135) is detected, a required amount of recording ink is supplied to the sub tank (135) from the ink cartridge (1 ').

  In this ink jet recording apparatus, when the recording ink in the ink cartridge (1 ′) of the present invention is used up, the casing (3 ′) of the ink cartridge (1 ′) is disassembled to disassemble the ink bag (2 ′ inside). ) Can only be exchanged. Further, the ink cartridge (1 ') can be stably supplied with the recording ink even when the ink cartridge (1') is vertically placed and has a front loading configuration. Therefore, even when the upper part of the apparatus main body (101) is closed and installed, for example, even when it is stored in a rack or an object is placed on the upper surface of the apparatus main body (101), the ink The cartridge (1 ′) can be easily replaced.

  Hereinafter, the present invention will be described in detail and specifically by way of examples. However, these examples are intended to facilitate understanding of the present invention and are not intended to limit the present invention. . In each example, “parts” and “%” represent “parts by weight” and “% by weight” unless otherwise specified.

[Preparation of pigment dispersion]
Each pigment dispersion was prepared as shown below.

<(1); Black dispersion A>
Pigment: Carbon black (NIPEX150-IQ, manufactured by Degussa, gas black) ... 200 parts by weight Dispersant: Polyoxyethylene (n = 40) β-naphthyl ether ... 50 parts by weight Water: Highly pure water ... 750 parts by weight After premixing the above mixture, using a bead mill disperser (manufactured by Kotobuki Kogyo Co., Ltd., UAM-015) and dispersing with zirconia beads having a diameter of 0.03 mm for 15 minutes at a peripheral speed of 10 m / s and a liquid temperature of 30 ° C. Then, coarse particles were centrifuged with a centrifuge (Model 3600, manufactured by Kuboyama Shoji Co., Ltd.) to obtain a black pigment dispersion A.

<(2); Cyan Dispersion A>
A cyan pigment dispersion A was obtained in the same manner as in (1) except that the pigment used in (1) was changed from carbon black to pigment blue 15: 3.

<(3); Magenta dispersion A>
The magenta dispersion was the same as (1) except that the pigment used in (1) was changed from carbon black to pigment red 122 and the dispersant used was changed to polyoxyethylene (n = 40) ammonium dodecyl sulfate. A was obtained.

<(4); Yellow dispersion A>
A yellow dispersion A was obtained in the same manner as in (3) except that the pigment used in (3) was changed from Pigment Red 122 to Pigment Yellow 74.

<(5); Black dispersion B>
Black dispersion B was obtained in the same manner as in (1) except that the amount of the dispersant used in (1) was changed to 5 parts by mass.

<(6); Cyan Dispersion B>
A cyan dispersion B was obtained in the same manner as in (2) except that the amount of the dispersant used in (2) was changed to 85 parts by mass.

<(7); Magenta dispersion B>
A magenta dispersion B was obtained in the same manner as in (3) except that the dispersant used in (3) was polyoxypropylene (n = 25) β-naphthyl ether.

<(8); Yellow dispersion B>
A yellow dispersion B was obtained in the same manner as in (4) except that the dispersant used in (4) was sorbitan monostearate.

<(9); Black dispersion C>
(Preparation of polymer solution)
After charging 1,000 parts of methyl ethyl ketone into a three-liter four-necked flask equipped with a dropping device, a thermometer, a nitrogen gas inlet tube, a stirring device and a reflux condenser, the temperature of the solution was raised to 78 ° C., A mixture of 700 parts of n-butyl methacrylate, 42 parts of n-butyl acrylate, 150 parts of 2-hydroxyethyl methacrylate, 108 parts of methacrylic acid and 80 parts of tertiary butyl peroxy-2-ethylhexanoate was taken over 4 hours. And dripped.
Furthermore, the reaction was continued at the same temperature for 8 hours.
The reaction mixture was allowed to cool to room temperature, and diluted by adding methyl ethyl ketone so that the non-volatile content was 50% to obtain a polymer solution.

(Preparation of carbon black pigment-containing polymer fine particle dispersion)
28 g of the polymer solution, 26 g of the carbon black pigment, 13.6 g of a 1 mol / L potassium hydroxide solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water were sufficiently stirred and then kneaded using a three-roll mill. By putting the obtained paste into 200 g of ion-exchanged water and stirring sufficiently, the methyl ethyl ketone and water are distilled off using an evaporator and filtered through a 5 μm filter (acetylcellulose membrane) to remove coarse particles. A black pigment dispersion C was obtained.

<(10); Cyan Dispersion C>
A cyan pigment dispersion C was obtained in the same manner as in (9) except that the pigment used in (9) was changed from carbon black to pigment blue 15: 3.

[Ink Preparation Example 1; Ink 1]
Black dispersion A 7.0 parts (as solid content)
20.0 parts glycerin (as solids)
1,3-butanediol 10.0 parts 1,2-pentanediol 3.0 parts Surfactant A 1.0 part (as an active ingredient)
High purity water remainder Total 100.0 parts The surfactant A used in Ink Preparation Example 1 is as follows.
Surfactant A: D-1007 (manufactured by Takemoto Yushi Co., Ltd.)
An ink composition having the above formulation was prepared, stirred at room temperature for 1 hour and 30 minutes, and then filtered through a membrane filter having an average pore size of 0.8 μm to obtain ink 1 (black ink) according to ink preparation example 1. .

[Ink Preparation Example 2; Ink 2]
Ink 2 (cyan ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

[Ink Preparation Example 3; Ink 3]
Ink 3 (magenta ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

[Ink Preparation Example 4]
Ink 4 (yellow ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

[Ink Preparation Example 5]
Ink 5 (black ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

[Ink Preparation Example 6]
Ink 6 (cyan ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

[Ink Preparation Example 7]
Ink 7 (magenta ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

[Ink Preparation Example 8]
Ink 8 (yellow ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

[Ink Preparation Example 9]
Ink 9 (black ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

[Ink Preparation Example 10]
Ink 10 (cyan ink) was obtained in the same manner as Ink Preparation Example 1, except that the ink formulation of Ink Preparation Example 1 was changed to that of the ink formulation shown in Table 1.

なお、各インク調製例で用いた界面活性剤Ａ〜Ｃは以下のとおりである。
界面活性剤Ａ ：Ｄ−１００７（竹本油脂社製）
界面活性剤Ｂ ：ＦＳ−３００（Ｄｕｐｏｎｔ社製）
界面活性剤Ｃ ：ＥＰ−７０２５（花王社製）

The surfactants A to C used in each ink preparation example are as follows.
Surfactant A: D-1007 (manufactured by Takemoto Yushi Co., Ltd.)
Surfactant B: FS-300 (manufactured by Dupont)
Surfactant C: EP-7005 (manufactured by Kao Corporation)

[Example 1]
As shown in the following Table 2, the ink 1 (black ink) was used, and the two pads were made of filter A (SUS 316L material shown in the following Table 3 with a surface Al abundance ratio of 0.0% and a surface Si abundance ratio. 1.9% stainless sintered filter) and the liquid permeability was evaluated.
That is, two metal bats were connected by a filter unit, and ink was poured so that the water head difference was 150 mm.
In the environment of 25 ° C., the ink was allowed to flow while maintaining a water head pressure of 150 mmaq, and the fluid resistance was calculated by measuring the outflow time per ink weight (g).
The rate of change in fluid resistance from the initial stage (ink flow rate of 0 g) to the time point of 4000 g of ink flow was calculated and evaluated according to the following criteria. The allowable range is up to ○.
[Evaluation criteria]
A: Increase in resistance from the initial stage is less than 10% B: Increase in resistance from the initial stage is 10% or more and less than 25% Δ: Increase in resistance from the initial stage is 25% or more and less than 50% ×: The increase in resistance from the beginning is 50% or more. The results are shown in Table 2.

[Example 2]
The combination of ink and filter shown in Table 2 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 2.

[Example 3]
The combination of ink and filter shown in Table 2 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 2.

[Example 4]
The combination of ink and filter shown in Table 2 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 2.

[Example 5]
The combination of ink and filter shown in Table 2 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 2.

[Example 6]
The combination of ink and filter shown in Table 2 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 2.

[Example 7]
The combination of ink and filter shown in Table 2 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 2.

[Example 8]
The combination of ink and filter shown in Table 2 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 2.

[Example 9]
The combination of ink and filter shown in Table 2 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 2.

As shown in the table, six types of filters were used for the evaluation.
“Surface Al abundance ratio” and “Surface Si abundance ratio” in the table represent the proportions of Al and Si in all the elements present on the surface, respectively. A scanning X-ray photoelectron spectrometer (ULVAC It is a value measured by Phi Co., Ltd./PHI Quantera SXM).

[Comparative Example 1]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 2]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 3]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 4]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 5]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 6]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 7]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 8]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 9]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 10]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 11]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 12]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

[Comparative Example 13]
The combination of ink and filter shown in Table 4 below was tested in the same manner as in Example 1 to evaluate liquid permeability. The results are shown in Table 4.

From the above results, it can be seen that in Examples 1 to 9, although a slight increase in resistance is observed in some of the examples using the mesh filter, extremely excellent liquid permeability is secured. Further, in Comparative Examples 1 to 3, which are examples using a filter in which the proportion of Al and Si in the surface element composition exceeds 5.0%, even if an appropriate ink is used, the aggregates of the pigments are filtered over time. It can be seen that the resistance increases greatly. Further, in Comparative Examples 4 and 5, which are examples using a filter made of a material other than stainless steel, liquid passage is hindered by a metal oxide or the like present on the surface, and agglomeration of pigments grows using that portion as a nucleus. Therefore, it can be seen that the resistance greatly increases. In Comparative Examples 6 to 9, which are examples in which the amount of the dispersant present in the ink is too small or too large relative to the pigment, if the amount is too small, the dispersion state becomes extremely unstable, and the number of coarse particles in the ink As a result, the resistance increases significantly. In addition, when the amount is too large, the ink tends to foam excessively, so that bubbles are mixed in and the liquid flow is inhibited.
Furthermore, in the case of Comparative Examples 10 and 11, which are examples in which the dispersant used does not have a polyoxyethylene chain, since the dispersant has a low dispersibility, it becomes unstable as an ink, and the pigment is easily filtered. It can be seen that the agglomerates and the resistance increases significantly.
In Comparative Examples 12 and 13, which are examples using a resin-coated pigment, the dispersion state itself is stable, but the generation of free resin cannot be suppressed, and the ink can be passed by sticking the resin to the filter. It can be seen that the liquid permeability is inferior because the liquid is inhibited.

1 'ink cartridge 101 apparatus main body 102 paper supply tray 103 paper discharge tray 104 ink cartridge loading unit 111 upper cover 112 front surface 115 front cover 131 guide rod 132 stay 133 carriage 134 recording head 135 sub tank 141 paper placement unit 142 paper 143 paper supply Roller 144 Separation pad 145 Guide 151 Conveying belt 152 Counter roller 153 Conveying guide 154 Pressing member 155 Tip pressure roller 156 Charging roller 157 Conveying roller 158 Tension roller 161 Guide member 171 Separating claw 172 Discharging roller 173 Discharging roller 181 Double-sided sheet feeding Unit 182 Manual paper feed unit 1 Frame 1-2 Common liquid chamber 2 Flow path plate 2-1 Fluid resistance unit 2-2 Pressurized liquid chamber 2-3 Communication port 2-4 Bulkhead 3 Nozzle plate (vibration plate)
3-1 Nozzle 4 Base 5 Multilayer Piezoelectric Element 5-5 Common Electrode 5-6 Drive Unit (Moving Part)
5-7 Supporting part 6 Diaphragm 6-1 Island-like convex part 6-2 Diaphragm part 6-3 Ink inflow port 7 Adhesive layer 8 FPC
DESCRIPTION OF SYMBOLS 10 Lever 13 Drive apparatus 20 Carriage 21 Atmospheric release pin 22 Negative pressure pin 23 Elastic member 30 Sub tank 31 Atmospheric release port 32 Negative pressure lever 33 Case 34 Film 35 Plate 36 Elastic member 37 Ink filling port 38 Full detection sensor 39a Top wall 39b Bottom Wall 39c Side wall 40 Inkjet head 50 Ink cartridge 51 Connecting tube 301, 302 Sub tank unit 311, 371 Elastic member 312, 372 Ball 313, 373 Elastic member 314, 374 Cap

JP-A-9-187955 JP-A-9-109411 JP 2005-324444 A JP 2006-070105 A JP 2004-204075 A JP 2009-173829 A JP 2005-288810 A

Claims (10)

  An ink supply unit that supplies ink containing at least water, a pigment, and a water-soluble organic solvent, wherein the ink supply unit includes a stainless steel filter, and the filter has a proportion of Al and Si in the composition of surface elements. The total amount is 5% or less, and the pigment of the ink is dispersed by a dispersant. The dispersant has an ethylene oxide chain as a hydrophilic group in the structure, and is 5. An ink supply unit comprising an amount corresponding to 0 to 40.0 wt%.   The ink supply unit according to claim 1, wherein the dispersant is a nonionic surfactant. The ink supply unit according to claim 1, wherein a structure of the surfactant is represented by the following general formula (1).

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, an allyl group, or an aralkyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200.)   The ink supply unit according to any one of claims 1 to 3, wherein the stainless steel constituting the filter is SUS316 or SUS316L.   The ink supply unit according to any one of claims 1 to 4, wherein the filter is a sintered filter obtained by laminating and sintering stainless fibers in a felt shape.   6. The ink supply unit according to claim 1, wherein the filter is a twill woven filter formed by twilling a stainless fiber.   An ink jet recording apparatus comprising the ink supply unit according to claim 1.   A plurality of pressurized liquid chambers, a nozzle having a pore diameter of 35 μm or less communicating with the pressurized liquid chamber, an ink supply path, an electric pressure converting means or an electrothermal converting means for discharging ink, a filter, and an ink tank for generating a negative pressure. Item 8. The ink jet recording apparatus according to Item 7.   An ink jet recording method comprising: forming an image on a recording medium by continuously ejecting ink droplets using the ink jet recording apparatus according to claim 7.   An ink recorded matter comprising an image formed by the ink jet recording method according to claim 9.

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