JP5482322B2 - Metal filter and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a metal filter and an image forming apparatus having the metal filter, and more particularly to a metal filter used in an ink flow path of an ink jet type image forming apparatus and an image forming apparatus having the filter in the ink flow path.

The ink jet recording technique is a technique in which ink is made into fine droplets by a pressure on-demand method or a charge control method, and the fine ink droplets are attached to a recording medium such as paper according to image information and recorded. Such an ink jet recording technique is suitably used for image forming apparatuses such as printers, facsimiles, and copying machines. Ink jet recording technology can form an image by directly depositing ink on a recording medium, so that recording can be performed with a simpler apparatus configuration than indirect recording using a photoreceptor such as electrophotographic recording. For this reason, further development is expected in the future as an image recording method on a sheet-like recording medium.
However, miniaturization of flying ink droplets is indispensable for realizing further high-definition images, and in order to eject minute droplets, one droplet of which is said to be several picoliters, ink droplets are smaller than before. It is considered that the nozzle hole itself for discharging the nozzle needs to be further miniaturized and miniaturized.
In order to stabilize the discharge and flight of ink from the nozzle holes, which are expected to be even smaller in the future, there is no foreign matter that stagnates the ink flow in the ink, or the vicinity of the nozzle holes It is necessary that there is no foreign matter that adheres to the liquid and deteriorates the discharge accuracy or makes the discharge impossible. For this reason, a metal filter is conventionally installed in the ink flow path for the purpose of removing foreign substances.
As this metal filter, a knitted metal fiber, a non-woven fabric-like binder, or a thin metal plate provided with holes by etching or plating has been used (for example, Patent Documents 1 and 2). reference).

  On the other hand, recently, water-based inks are known as ink-jet inks. This water-based ink uses a resin emulsion in which a resin fine particle contains a water-insoluble or hardly soluble color material as a color material (see, for example, Patent Documents 3 to 5). In this case, it is estimated that the amount of “free polymer” described in Patent Document 4 affects various ink performances.

  In the above-described ink jet recording technique using a metal filter, when the above-described aqueous ink is used, the water-based ink is deteriorated in passability due to clogging of the filter due to a free polymer, and the filter resistance is increased. As a result, ink ejection becomes unstable, such as an insufficient ink supply amount, and a non-ejection state occurs. In addition, although this free polymer is a foreign substance, it is very fine, and if it has a certain amount of concentration in the ink, it does not immediately lead to deterioration of the ink ejection properties. When a large amount is supplied and passed, adhesion, aggregation and deposition occur on the surface of the metal filter, and as a result, the filter resistance (filtration resistance) may increase.

  Also, in systems that require large-scale printing and printing that tend to cause an increase in filter resistance, particularly high-speed inkjet printers equipped with line heads, the need for metal filters is much higher than that of serial printers. For this reason, the invention of the metal filter which does not produce adhesion, agglomeration, and deposition easily and the high-speed inkjet printer using this filter are desired.

The present invention has been made in view of the above-mentioned problems in the prior art, and provides a metal filter that is disposed in an ink flow path of an ink jet type image forming apparatus and that does not substantially clog. The purpose is to do.
Another object of the present invention is to provide an ink jet image forming apparatus having such a metal filter in an ink flow path.

The present invention has been made to solve the above-described problems, and is characterized by having the following solution means.
(1) A metal used in an ink flow path of an ink-jet image forming apparatus of an aqueous ink containing a resin emulsion in which a resin fine particle contains a water-insoluble or hardly soluble coloring material, a water-soluble solvent, and water. In the filter, the metal filter is characterized in that a metal substrate is coated with at least one of perfluoropolyoxetane or modified perfluoropolyoxetane.
(2) The metal filter according to (1), wherein the substrate is coated by vapor deposition with a thickness of 0.1 nm to 3 nm on the substrate.
(3) In the metal filter according to (1) or (2), the base is a metal thin plate having holes formed by etching or plating, and the deposited film is removed on the side surfaces of the holes. And
(4) The metal filter according to any one of (1) to (3), wherein the metal filter is a Ni electroformed filter, and an opening diameter thereof is 5 μm to 10 μm.
(5) An inkjet image forming apparatus using the metal filter according to any one of (1) to (4) in a water-based ink flow path.

  At least one kind of perfluoropolyoxetane or modified perfluoropolyoxetane (including a mixture thereof) is attached to the surface of the metal filter by adhering “free polymer” contained in water-based ink used in an inkjet image forming apparatus. By covering the surface, it is possible to provide an image forming apparatus that can prevent instability and non-ejection of ink ejection and can stably provide high-quality recording.

It is an enlarged view which shows one example of the metal filter of this invention which formed the specific compound in the predetermined film thickness on the surface of the metal filter. It is an enlarged view which shows the example of the aspect which removed the side wall part of the hole of the metal filter of this invention. It is a figure which shows the apparatus structural example of the image forming apparatus carrying the metal filter of this invention. It is the graph which measured the change of the filtration resistance by the ink flow using the metal filter by the Example shown in Table 1, and a comparative example, a horizontal axis represents liquid flow volume (g), and a vertical axis | shaft represents filter resistance [Pa *. s / m ³ ]. It is the graph which measured the change of the filtration resistance of the ink from which a pigment kind differs using the metal filter of this invention, a horizontal axis | shaft represents liquid flow amount (g), and a vertical axis | shaft represents filter resistance [Pa * s / m < ³ >]. Represents. It is the graph which measured the change of the filtration resistance by the ink flow which used the metal filter from which a base | substrate differs, A horizontal axis | shaft represents liquid flow amount (g) and a vertical axis | shaft represents filter resistance [Pa * s / m < ³ >]. . It is the graph which measured the change of the filtration resistance by the ink flow which used the metal filter of Examples 6-8 shown in Table 2, and Comparative Examples 06-07, A horizontal axis represents liquid flow amount (g), and a vertical axis | shaft Represents filter resistance [Pa · s / m ³ ]. It is the graph which measured the change of the filtration resistance by the ink flow using the metal filter of the present invention, and shows an example in which the filter wall was not removed and the removed one, and the horizontal axis represents the flow rate (g). The vertical axis represents the filter resistance [Pa · s / m ³ ].

  The metal filter of the present invention preferably has a metal filter knitted with metal fibers, a metal fiber bonded like a nonwoven fabric, or a thin metal plate with holes formed by etching or plating. The substrate is coated with at least one perfluoropolyoxetane or modified perfluoropolyoxetane, preferably a mixture thereof, and preferably has a film thickness of 0.1 nm to 3 nm (1 mm) on the substrate. ~ 30mm). A method of depositing at least one kind of modified perfluoropolyoxetane, preferably a mixture (coating material) thereof, under vacuum is, for example, mounting the substrate in a vacuum chamber with a vacuum exhaust pump, and a predetermined degree of vacuum. After evacuating, these coating materials are vaporized at about 400 ° C. and introduced into a vacuum chamber, the vacuum atmosphere is adjusted, and power is supplied from a high-frequency power source to the discharge electrode to cause an RF glow discharge. The substrate is surface-treated below to form a surface layer of the coating material on the substrate. Depending on the material and the degree of vacuum in the vacuum chamber, it is possible to form a surface layer at room temperature to a low temperature of about 200 ° C.

More preferably, the filter of the present invention is a substrate in which a hole is formed by etching or plating a thin metal plate, and the deposited film on the side surface of the filter hole is removed as shown in FIG. As a method for removing the perfluoropolyoxetane and the modified perfluoropolyoxetane film on this side, for example, removal from the back surface by a dry etching method may be mentioned, and this method is recommended. For example, a method of performing plasma dry etching in which plasma is generated by circulating a high-pressure oxygen atmosphere through a parallel plate type electrode can be exemplified.
More preferably, the base of the metal filter used as shown in FIG. 1 is a Ni electroformed filter, and the opening diameter (hole diameter) is 5 μm to 10 μm.

  For the vapor deposition of a mixture of perfluoropolyoxetane and modified perfluoropolyoxetane performed in a preferred embodiment of the present invention, for example, Daikin Industries, Ltd., trade name: OPTOOL DSX is preferably used, and the film thickness is 0.1 nm to It is preferable to set to 3 nm (1 to 30 cm). However, in this invention, even if it is not the thing of the said brand name for vapor deposition of the said mixture, this can be used if it has an equivalent effect. In addition, as modification | denaturation of perfluoropolyoxetane, the alkoxysilane terminal modification | denaturation (modification of the terminal group by an alkoxysilane group) can be mentioned.

  In a preferred embodiment of the present invention, the pigment that can be used in the water-based ink to be filtered is a resin emulsion in which a carboxyl group-containing resin fine particle contains a water-insoluble or hardly soluble coloring material, that is, a carboxyl group-modified polymer emulsion. . Here, “containing a color material” means having either or both of a state in which a color material is enclosed in polymer fine particles and a state in which a color material is adsorbed on the surface of the polymer fine particles. . In this case, the color material blended in the ink used in the present invention does not need to be completely enclosed or adsorbed in the polymer fine particles, and the color material is dispersed in the emulsion as long as the effect of the present invention is not impaired. You may do it. The color material is not particularly limited as long as it is water-insoluble or hardly water-soluble and can be adsorbed by the carboxyl group-modified polymer. In this specification, water-insoluble or poorly water-soluble means that the coloring material does not dissolve 10 parts by weight or more with respect to 100 parts by weight of water at 20 ° C. It means that separation and sedimentation are not visually recognized.

  Examples of the coloring material include dyes such as oil-soluble dyes and oil-dispersed dyes, and pigments. Oil-soluble dyes and disperse dyes can be used from the viewpoint of good adsorption / encapsulation properties, but pigments are preferably used from the light resistance of the obtained image. In addition, as the polymer used at this time, a polymer having a carboxyl group, for example, a polymer such as polyacrylic acid or polymethacrylic acid is used, and the blending amount of the coloring material depends on the blending amount of the polymer. It is preferably about 10 to 200% by weight, particularly about 25 to 150% by weight based on the weight of The blending amount of these carboxylic acid-modified polymer emulsions in the aqueous ink is 1 to 20 wt%, preferably 3 to 12 wt%, more preferably 5 to 10 wt%. Ink in this range can be coagulated and solidified by cross-linking the pigment having carboxylic acid on the surface by applying a pretreatment liquid containing a carbodiimide group on the substrate, and the coloring material remains on the paper surface. . By this phenomenon, the density drop, the fixing drop, the blur, and the same effect can be prevented from see-through and beading.

  More specifically, examples of pigments that can be contained in the carboxyl group-containing resin fine particles include organic pigments and inorganic pigments. For example, carbon blacks such as furnace black, lamp black, acetylene black, and channel black are used for black and white. (CI pigment black 7), or metals such as copper, iron (CI pigment black 11), titanium oxide, and organic pigments such as aniline black (CI pigment black 1). . Further, for color use, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 81, 83 (Disazo Yellow HR) ), 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 153, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48 : 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (Quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, CI. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19 (quinacridone red), 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 127 (bitumen ), 28 (cobalt blue), 29 (ultraviolet), 56, 60, 63, C.I. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, etc., and a plurality of them may be used in combination. Moreover, it is not limited to these.

These pigments may be used alone or in combination of two or more.
The amount of these pigments is 1 to 25 wt%, preferably the carboxyl group-containing pigment is 1 to 25 wt%, more preferably 5 to 15 wt%. The ink in this range can reliably and effectively cross-link with the carbodiimide group-containing water-soluble resin contained in the pretreatment liquid, increase the concentration, suppress bleeding, and prevent a decrease in fixing.

In a preferred embodiment of the present invention, a water-soluble solvent can be used in the water-based ink. This water-soluble solvent is a so-called water-soluble organic solvent.
Examples of the water-soluble organic solvent include 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3- Hexanediol, glycerin, 1,3-butanediol, triethylene glycol, 1,6-hexanediol, propylene glycol, 1,5-pentanediol, diethylene glycol, dipropylene glycol, trimethylolpropane, trimethylolethane or ethylene glycol 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,2,6-hexanetriol, 1 , 2, -Hydroxy compounds such as butanetriol, 1,2,3-butanetriol, thiodiglycol, pentaerythritol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene Polyhydric alcohol alkyl ethers such as glycol monomethyl ether and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; 2-pyrrolide, N-methyl-2- Pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε- Nitrogen-containing heterocyclic compounds (lactams) such as caprolactam and γ-butyrolactone; Amides such as formamide, N-methylformamide and N, N-dimethylformamide; Sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol ; Propylene carbonate, ethylene carbonate and the like. The blending amount of these water-soluble organic solvents in the water-based ink is 10 to 50 wt%. These water-soluble organic solvents may be used alone or in combination. Moreover, it is not limited to these.

Moreover, in the water-based ink to be filtered by the filter of the present invention, various materials conventionally used in ink jet recording inks can be included as necessary.
Examples of such materials include surfactants, pH adjusters, preservatives, and rust inhibitors.
For example, the surfactant is not particularly limited, but can be appropriately selected from surfactants that do not impair dispersion stability depending on the purpose, depending on the type of colorant, a wetting agent, a penetrating agent, and the like. . Particularly when printing on printing paper, those having low surface tension and high leveling properties are preferred, and at least one selected from silicone surfactants and fluorosurfactants is preferred. Among these, a fluorine-based surfactant is particularly preferable.

  Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate ester compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. The polyoxyalkylene ether polymer compound having a low foaming property is particularly preferable.

  Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylate.

  Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters and perfluoroalkyl phosphate salts. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain include a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a perfluoroalkyl ether group in the side chain. Examples thereof include salts of polyoxyalkylene ether polymers.

  As the fluorosurfactant, those appropriately selected may be used, or commercially available products may be used. Examples of the commercially available products include Surflon series (S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145) manufactured by Asahi Glass Co., Ltd. Full Lard Series (FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431) manufactured by 3M, MegaFac Series manufactured by Dainippon Ink (F-470, F-1405, F-474, Dupont Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR), Neos FT-110, FT-250, FT-252, FT-400S, FT-150, FT-400SW, OM-nova PF-151N, etc. are mentioned, among these, good FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW and OMNOVA manufactured by Neos Co., Ltd. from the standpoint of significantly improving print quality, especially color development and leveling on paper. PF-151N is particularly preferred.

As counter ions (counter ions) of salts in these fluorosurfactants, Li ⁺ , Na ⁺ , K ⁺ , NH ₄ ⁺ , (NH ₃ CH ₂ CH ₂ OH) ⁺ , [NH ₂ (CH ₂ CH ₂ OH) ₂ ] ⁺ , [NH (CH ₂ CH ₂ OH) ₃ ] ^{+ and the} like. These counter ions may be derived from a pH adjusting agent.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the purpose, and those that do not decompose even at high pH are preferable. For example, side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, piece Examples include terminal-modified polydimethylsiloxane and side-chain both-end-modified polydimethylsiloxane, and those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group exhibit good properties as an aqueous surfactant. Particularly preferred. As such a surfactant, an appropriately synthesized product or a commercially available product may be used.
Such commercially available products can be easily obtained from, for example, Big Chemie, Shin-Etsu Silicone, Toray Dow Corning Silicone. The polyether-modified silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include compounds in which a polyalkylene oxide structure is introduced into the side chain of the dimethylpolysiloxane in the Si part. .

As said polyether modified silicone compound, what was synthesize | combined suitably may be used and a commercial item may be used.
As this commercial item, Shin-Etsu Chemical Co., Ltd. KF-618, KF-642, KF-643 etc. are mentioned, for example. In addition to the fluorine-based surfactant and the silicone-based surfactant, anionic surfactants, nonionic surfactants, amphoteric surfactants, and the like can be used.

  Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, succinate sulfonate, laurate, polyoxyethylene alkyl ether sulfate, and the like.

  Examples of the nonionic surfactant include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and the like. 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, , 5-dimethyl-1-hexyn-3-ol and the like.

  Examples of the acetylene glycol surfactant include commercially available Surfynol series (104, 82, 465, 485, TG) manufactured by Air Products.

  Examples of amphoteric surfactants include lauryl amino pyropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, lauryl dimethyl amine oxide, myristyl dimethyl amine oxide, stearyl dimethyl amine oxide, dihydroethyl lauryl amine oxide, Polyoxyethylene coconut oil alkyldimethylamine oxide, dimethylalkyl (coconut) betaine, dimethyl lauryl betaine and the like can be mentioned.

  As such surfactants, commercially available products such as Nikko Chemicals, Nihon Emulsion, Nippon Shokubai, Toho Chemical, Kao, Adeka, Lion, Aoki Yushi, Sanyo Kasei, etc. Available at: The surfactant is not limited to these, and may be used alone or in combination. Even if it is not easily dissolved in the recording ink alone, it can be solubilized by mixing and exist stably.

  The content of the surfactant in the recording ink is preferably 0.01% by mass to 3% by mass, and more preferably 0.5% by mass to 2% by mass. However, the total content of the liquid components that are liquid in the ink at 25 ° C. having a boiling point higher than that of water is 20% by mass or less, and preferably 15% by mass or less. When the content is less than 0.01% by mass, the effect of adding a surfactant may be lost. On the other hand, when the content exceeds 3% by mass, the permeability to a recording medium is unnecessarily high and the image density is lowered. And strikethrough may occur.

  For example, it means an emulsion having a resin emulsion in which the continuous phase with the resin emulsion is water and the dispersed phase is the following resin component. The resin emulsion has the property of thickening and aggregating, has the effect of suppressing the penetration of the coloring components, and further promoting the fixing to the recording material. Depending on the type of the resin emulsion, it is possible to select one having an effect of forming a film on the recording material and improving the abrasion resistance of the printed matter. Examples of the resin component in the dispersed phase include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, and styrene resins. These resins are preferably polymers having both a hydrophilic part and a hydrophobic part. The particle size of these resin components is not particularly limited as long as an emulsion is formed, but is preferably about 150 nm or less, more preferably about 5 to 100 nm.

These resin emulsions can be obtained by mixing resin particles in water, optionally with a surfactant. For example, as an emulsion of acrylic resin or styrene-acrylic resin, (meth) acrylic acid ester, or (meth) acrylic acid ester and styrene and other polymerizable monomers such as styrene polymerized in water together with a polymerization initiator It can be obtained by mixing a surfactant with water. The mixing ratio of the resin component A and the surfactant B (A: B weight ratio) is usually preferably about 10: 1 to 5: 1.
When the amount of the surfactant used is less than the above range, it is difficult to form an emulsion, and when it exceeds the above range, the water resistance of the ink tends to be lowered or the penetrability tends to deteriorate.

  The ratio of the resin and water as the dispersed phase component of the emulsion is suitably 60 to 400 parts by weight, preferably 100 to 200 parts by weight, based on 100 parts by weight of the resin. Commercially available resin emulsions include Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden Chemical Co., Ltd.) Company-made).

  In the present invention, in order to prevent ejection failure, a pH adjuster is added to keep the solution alkaline. As a result, the dispersed state of the ink is stabilized, and the ejection can be stabilized. Accordingly, the pH of the water-based ink is preferably 7 or more and less than 11. When the pH is 11 or more, the ability to dissolve the material of the ink jet head and the ink supply unit increases, and problems such as ink deterioration, leakage, and ejection failure may occur. On the other hand, when the pH is less than 7, the ink dispersion state may be deteriorated.

  In the present invention, the pH adjusting agent used in the ink to be used is more preferably added to water when kneading and dispersing the pigment together with the dispersant, together with additives such as a wetting agent and a penetrating agent. This is because the dispersion may be destroyed by adding some pH adjusters. Examples of the pH adjuster include alcohol amines, alkali metal hydroxides, ammonium hydroxides, phosphonium hydroxides, and alkali metal carbonates. Examples of the alcohol amines include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol, and the like. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the ammonium hydroxide include ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, and the like. Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, potassium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate.

  Examples of the antiseptic / antifungal agent used in the ink used in the present invention include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, sodium pentachlorophenol, 1,2benzisothiazoline. -3-one etc. are mentioned.

Examples of the rust inhibitor used in the ink used in the present invention include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and benzotriazole.
In addition, a metal ion sealing agent, a (water-soluble) ultraviolet absorber, a (water-soluble) infrared absorber, and the like can be added depending on the purpose.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not construed as being limited to the following examples.

(Production Example 1)
Preparation of polymer emulsion comprising polymer fine particles containing water-insoluble or poorly soluble colorant (a) Preparation of phthalocyanine pigment-containing polymer fine particle dispersion: Preparation Example 3 described in JP-A No. 2001-139849 A blue polymer fine particle dispersion was obtained. Specifically, it is as follows.
(1) Preparation of polymer solution The inside of a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel was sufficiently purged with nitrogen gas, and then 11.2 g of styrene and acrylic acid 2. 8 g, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were charged and heated to 65 ° C. .
Next, styrene 100.8 g, acrylic acid 25.2 g, lauryl methacrylate 108.0 g, polyethylene glycol methacrylate 36.0 g, hydroxyethyl methacrylate 60.0 g, styrene macromer (manufactured by Toagosei Co., Ltd., trade name: AS-6) ) A mixed solution of 36.0 g, mercaptoethanol 3.6 g, azobisdimethylvaleronitrile 2.4 g and methyl ethyl ketone 18 g was dropped into the flask over 2.5 hours.
After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added, and further aging was performed for 1 hour.
After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50%.
A part of the polymer solution was dried and measured by gel permeation chromatography (standard: polystyrene, solvent: tetrahydrofuran), and the weight average molecular weight was 15000.

(2) Preparation of aqueous dispersion of polymer fine particles of phthalocyanine pigment 28 g of polymer solution obtained in (1) above, phthalocyanine pigment (manufactured by Dainippon Ink & Chemicals, trade name: TGR-SD) 26 g, 1 mol / After 13.6 g of L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone and 30 g of ion-exchanged water were sufficiently stirred, the mixture was kneaded 20 times using a three-roll mill (manufactured by Noritake Co., Ltd., trade name: NR-84A).
The obtained paste was put into 200 g of ion-exchanged water, and after sufficiently stirring, methyl ethyl ketone and water were distilled off using an evaporator, and 160 g of an aqueous dispersion of phthalocyanine pigment-containing polymer fine particles having a solid content of 20.0% by weight. Got. The average particle size (D50%) of the polymer fine particles measured by Microtrac UPA was 93 nm.

(Production Example 2)
(B) Preparation of dimethylquinacridone pigment-containing polymer fine particle dispersion: A red-purple polymer fine particle dispersion was obtained in the same manner as in Production Example 1 except that the phthalocyanine pigment in (a) was changed to Pigment Red 122. The average particle diameter (D50%) of this polymer fine particle measured by Microtrac UPA was 127 nm.

(Production Example 3)
(C) Preparation of monoazo yellow pigment-containing polymer fine particle dispersion: A yellow polymer fine particle dispersion was obtained in the same manner as in Production Example 1 except that the phthalocyanine pigment of (a) was changed to Pigment Yellow 74. The average particle diameter (D50%) of this polymer fine particle measured by Microtrac UPA was 76 nm.

(Production Example 4)
(D) Preparation of carbon black-containing polymer fine particle dispersion: A black polymer fine particle dispersion was obtained in the same manner as in Production Example 1 except that the phthalocyanine pigment of (a) was changed to carbon black (Degussa FW100). The average particle diameter (D50%) of the polymer fine particles measured by Microtrac UPA was 104 nm.

Ink preparation method (i) Pigment: a polymer emulsion produced by the above-described production examples 1 to 4 and containing a water-insoluble or hardly soluble colorant in the self-dispersing pigment / polymer fine particles 8 parts by weight (ii) interface Activator ... Nonionic: 2 parts by weight (iii) Water-soluble organic solvent ... Polyoxypropylene diglyceryl ether, glycerin, 1,3-butanediol
25 parts by weight (iv) pure water remainder (v) pH adjuster ... organic amine (triethanolamine)
0.5 parts by weight (vi) preservative
0.1 parts by weight (vii) rust inhibitor
0.1 parts by weight

  The above (iv) pure water, (iii) water-soluble organic solvent, (vi) antiseptic and (vii) rust inhibitor were added, and dispersed and stirred with a dissolver (DISPERMAT-FE) to prepare a resin dispersion. In this resin dispersion, (i) a pigment and optionally (ii) a surfactant are added, and when the pigment is an unmodified pigment, it is dispersed and stirred with a bead mill (Ashizawa-Labstar). When the pigment is a carboxyl group-modified pigment, a dissolver is used. A pigment dispersion was prepared by dispersing and stirring with (DISPERMAT-FE). This pigment dispersion was filtered through a 3 μm filter to obtain an ink for inkjet recording.

Example 1
Example of metal filter production As a base of a metal filter, a 100 μm thick Ni electroformed plate (filter opening diameter: filter hole diameter: 10 μm, hole density 25/100 × 100 μm ² ) was used, and perfluoropolyoxetane and modified par A mixture of fluoropolyoxetane (Optool (trademark) DSX manufactured by Daikin Industries, Ltd.) is vaporized at about 400 ° C. and introduced into a vacuum chamber, the vacuum atmosphere is adjusted, and power is supplied from a high frequency power source to the discharge electrode to generate RF glow. Discharge was caused and surface treatment was performed in a plasma atmosphere to obtain a metal filter having a deposited film thickness of 1 nm (10 mm).

Examples 2-3 and Comparative Examples 1-3
Using the same metal filter substrate as in Example 1, a metal filter was formed by changing the deposition film thickness as shown in Table 1.

Examples 4-8 and Comparative Examples 4-7
Using a substrate shown in Table 2, a mixture of perfluoropolyoxetane and modified perfluoropolyoxetane (Optool (trademark) DSX manufactured by Daikin Industries, Ltd.) in the same manner as described above is shown in Table 2. In this way, a metal filter was created. In Example 8, after forming the metal filter shown in Example 2, a coating film on the surface was formed by a dry etching method, and then the film on the side wall of the hole was removed. This dry etching process was performed by plasma dry etching in which a high-pressure oxygen atmosphere was circulated through parallel plate-type electrodes and discharged.

3. Evaluation Method of Filter Resistance Inks were prepared using the pigment seeds shown in Tables 1 and 2, and the ink was passed through the filters of Examples and Comparative Examples.
The pressure resistance before and after the filter unit in these Examples and Comparative Examples ([Pa · s / m ³ ]) was measured to calculate the filter resistance.
The filter resistance due to the passage of the filter unit with respect to the increase of the passage amount was compared under each condition.

FIG. 3 is a schematic diagram showing the internal structure of the droplet discharge device used for the continuous discharge evaluation of the present invention. In the image recording apparatus A, the paper feed tray 1 has a configuration in which a pressure plate 2 and a paper feed rotating body 4 for feeding the recording paper 3 are attached to a base 5. The pressure plate 2 can rotate around a rotation axis a attached to the base 5, and is urged by the spring 6 to the sheet feeding rotating body 4.
A separation pad (not shown) made of a material having a large coefficient of friction such as an artificial skin is installed at a portion of the pressure plate 2 facing the sheet feeding rotating body 4 in order to prevent double feeding of the recording paper 3. . Further, a release cam (not shown) for releasing the contact between the pressure plate 2 and the sheet feeding rotator 4 is provided at a portion of the pressure plate 2 facing the sheet feeding rotator 4.

In the above configuration, the release cam pushes the pressure plate 2 down to a predetermined position in the standby state. As a result, the contact between the pressure plate 2 and the sheet feeding rotating body 4 is released. In this state, when the driving force from the transport roller 7 is transmitted to the sheet feeding rotator 4 and the release cam by a gear or the like, the release cam moves away from the pressure plate 2 and the pressure plate 2 rises, and the sheet feeding rotator 4 and the recording are recorded. The paper 3 comes into contact.
The recording paper 3 is picked up with the rotation of the paper feed rotator 4 to start paper feed, and is separated one by one by a separation claw (not shown). The sheet feeding rotator 4 rotates to feed the recording sheet 3 to the platen 10 via the conveyance guides 8 and 9.
The recording paper 3 passes between the conveyance guides 8 and 9, is guided to the conveyance roller 7, and is conveyed to the platen 10 by the conveyance roller 7 and the pinch roller 11. After that, the contact state between the recording paper 3 and the paper feed rotating body 4 is released again, and the driving force from the transport roller 7 is cut off.
The paper feed rotator 12 for manual paper feed feeds the recording paper 3 mounted on the manual feed tray 13 by the paper feed rotator 12 in accordance with a recording command signal of the computer and transports it to the transport roller 7. .
The recording paper 3 conveyed to the platen 10 passes under the line head 14. Here, the recording paper conveyance speed and the droplet discharge timing are based on signals controlled by an electric circuit (not shown), thereby forming a desired image.

Using such an image forming apparatus, the change in filtration resistance due to the filters prepared in the above-described Examples and Comparative Examples was obtained using the above-described filter resistance evaluation method.
The obtained results are shown in Tables 1 and 2.
The results shown in Table 1 are obtained by determining the filtration resistance by using a filter having a base prepared under various conditions by Ni electroforming.
FIG. 4 is a graph showing changes in filtration resistance of the same pigment types of the ink to be filtered among those shown in Table 1.
Against the Comparative Example 0 1 forming no coating film,施例1-3 metal filter of the present invention, it can be seen that the increase in the filtration resistance is suppressed.
FIG. 5 is a graph showing changes in filtration resistance when the same metal filter of the present invention is used (Example 2 and Comparative Example 03) and the pigment type of the filtration object is changed.
FIG. 6 is a graph comparing changes in filtration resistance between the filter of the present invention and the conventional filter when a substrate having a different base from that in Table 1 is used. In addition, the example (Example 2) which used Ni electroforming shown in Table 1 as a base | substrate was plotted as a comparison.
“Vapor deposition of a mixture of perfluoropolyoxetane and modified perfluoropolyoxetane” is effective even in “knitted stainless steel fibers” and “knitted stainless steel fibers” as a substrate (Comparative Example 04, Examples) 4 and Comparative Example 05, Example 5). Since the conditions for vapor deposition on the substrate are the same as the above conditions, the description is omitted.

FIG. 7 shows the results shown in Table 2, which are the same as those used in Table 1 as the substrate, and two types with different thicknesses of the coating films in which the side walls of the holes remain (Example 6, 7) A graph in which the side wall of the hole is removed (Example 8) is compared with Comparative Examples 06 to 07 having no coating film.
It can be seen that when the filter pore size is large (20 μm) or small (10 μm), the effect of “deposition of a mixture of perfluoropolyoxetane and modified perfluoropolyoxetane” becomes small (Example 6, Comparative Example 06). There is an effect.
FIG. 8 shows examples of the metal filter of the present invention, in which the conditions are the same except that the side wall of the hole remains (Example 2) and the side wall of the hole is removed (Example 8). Are shown in comparison.
It can be seen that removing the “deposition film of a mixture of perfluoropolyoxetane and modified perfluoropolyoxetane” on the side of the filter hole increases the effect (Examples 2 and 8). This is probably because the filtration resistance was lowered due to the improvement of the wettability of the pores.

    DESCRIPTION OF SYMBOLS 1 Paper feed tray, 2 Pressure plate, 3 Recording paper, 4 Paper feed rotation body, 5 Base, 6 Spring, 7 Transport roller, 8-9 Transport guide, 10 Platen, 11 Pinch roller, 12 Paper feed rotation body, 13 Manual feed tray , 14 Carriage, 15 Inkjet head, A Image recording device, a Rotating shaft

JP 2009-178766 A JP 2001-253083 A WO 2006/137393 brochure JP2009-84501 JP2008-50400

Claims (5)

In a metal filter used in an ink flow path of an ink jet type image forming apparatus of a water-based ink containing a resin emulsion containing a water-insoluble or hardly soluble coloring material in a resin fine particle, a water-soluble solvent, and water,
The metal filter is characterized in that a metal base is coated with at least one of perfluoropolyoxetane or modified perfluoropolyoxetane.   The metal filter according to claim 1, wherein the metal filter is coated on the substrate with a thickness of 0.1 nm to 3 nm by vapor deposition.   3. The metal filter according to claim 1, wherein the base is a thin metal plate in which holes are formed by etching or plating, and the deposited film is removed on a side surface of the holes.   The metal filter according to any one of claims 1 to 3, wherein the metal filter is a Ni electroformed filter, and an opening diameter thereof is 5 µm to 10 µm.   An ink jet type image forming apparatus, wherein the metal filter according to claim 1 is used in a flow path of water-based ink.