JP6870310B2 - Cleaning solution, cleaning method and printing equipment - Google Patents

Description

The present invention relates to cleaning solutions, cleaning methods and printing devices.

Conventionally, as a recording device such as a printer, a facsimile, a copying device, a plotter, or a multifunction device thereof, an ink ejection type recording apparatus provided with a nozzle for ejecting ink has been known.
On the other hand, as inks used in inkjet recording devices, pigment inks have been widely used in recent years because of their excellent water resistance and light resistance.
Inkjet recording devices that use pigment ink have also come to be used in commercial printing applications such as high-speed continuous book machines. In such commercial printing applications, impermeable ink with low ink absorption is low as a printing medium. Even when a coated paper for printing, which is a base material, is used, it is required to obtain image quality comparable to that of conventional offset printing, and therefore measures have been taken to improve the fixability of the ink. Therefore, it is considerably more difficult than before to secure the ink ejection reliability as a contradictory characteristic. In particular, the ink having improved fixability easily adheres to the nozzle surface or the like, and the adhered ink cannot be completely removed by wiping the nozzle surface using a conventional rubber blade or the like.

On the other hand, various measures have been taken as a maintenance mechanism.
For example, in Patent Document 1 (Patent No. 5402978), in an inkjet recording device that ejects a water-based ink containing a resin for improving fixability, a rotating roller in which a part of the ink is immersed in a cleaning liquid stored in a container is used. Indicates a recording device that wipes and absorbs ink adhering to the ink ejection portion of the recording head. However, with this technique, it has been difficult to remove deposits on the nozzle surface when an ink containing a larger amount of resin for improving fixability is used.

Therefore, an object of the present invention is to satisfactorily remove ink stains adhering to the nozzle surface in a cleaning liquid used for a printing apparatus provided with a nozzle for ejecting ink, reduce deterioration of water repellency of the nozzle surface, and reduce deterioration of water repellency of the nozzle surface. The purpose is to provide a cleaning solution capable of suppressing damage.

The problem is solved by the following configuration 1).
1) A cleaning liquid that cleans the nozzle surface of a printing device equipped with a nozzle that ejects ink.
When the organic solvent contained in the ink is the organic solvent (1),
The cleaning liquid contains the same organic solvent as the organic solvent (1) contained in the ink, and contains the same organic solvent.
The content of the organic solvent (1) in the cleaning liquid is 30 to 50% by mass with respect to the entire cleaning liquid.
The cleaning liquid contains an organic solvent (2) that is not contained in the ink.
The content of the organic solvent (2) in the cleaning liquid is 10 to 20% by mass with respect to the entire cleaning liquid, and the content of all the organic solvents contained in the cleaning liquid is 50 to 70 with respect to the entire cleaning liquid. % by mass it is,
The organic solvent (1) is 3-methoxy-N, N-dimethylpropionamide.
A cleaning liquid characterized in that the organic solvent (2) is a glycol ether-based organic solvent.

According to the present invention, in a cleaning liquid used for a printing apparatus provided with a nozzle for ejecting ink, ink stains adhering to the nozzle surface are satisfactorily removed, deterioration of water repellency of the nozzle surface is reduced, and the nozzle surface is damaged. It is possible to provide a cleaning liquid capable of suppressing the above.

It is a perspective explanatory view of a recording device. It is a perspective explanatory view of a main tank. It is the schematic which shows an example of the cleaning means in the printing apparatus of this invention.

Hereinafter, modes for carrying out the present invention will be described.

<Ink>
Hereinafter, the organic solvent, water, coloring material, resin, additive, etc. used for the ink will be described.

<Organic solvent>
The organic solvent used in the present invention is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include ethers such as polyhydric alcohols, polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol , 2,4-Pentanediol, 1,5-Pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, Glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl- Polyhydric alcohols such as 1,3-pentanediol and 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 glycol monoethyl Polyhydric alcohol alkyl ethers such as ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone. , 1,3-Dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone and other nitrogen-containing heterocyclic compounds, formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, N- Amidos such as dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine and triethylamine, sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol, propylene carbonate and ethylene carbonate. And so on.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or lower because it not only functions as a wetting agent but also has good drying properties.

The organic solvent used for the ink is referred to as "organic solvent (1)" in the present specification.
The organic solvent (1) is also contained in the cleaning liquid of the present invention described below, but the content of the organic solvent (1) in the ink is, for example, 3 to 20% by mass, preferably 5 to 15% by mass. %.
Among the organic solvents (1), 3-methoxy-N and N-dimethylpropionamide are particularly preferable. By containing 3-methoxy-N, N-dimethylpropionamide in the ink, the adhesion, scratch resistance, non-transferability and high glossiness of the ink image can be improved. In particular, even if the recording medium to be printed matter is a non-permeable base material, the adhesion can be improved. In addition, 3-methoxy-N and N-dimethylpropionamide also have a high moisturizing effect and are effective in ensuring the reliability of the ink.
As the 3-methoxy-N, N-dimethylpropionamide, commercially available ones can be used, and examples thereof include the trade name "Equamid M-100" (manufactured by Idemitsu Kosan Co., Ltd.).

Further, from the viewpoint of ink permeability, it is preferable to use a polyol compound having 8 or more carbon atoms in combination with the organic solvent (1). Specific examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol and the like. The content of the polyol compound having 8 or more carbon atoms is, for example, 0.5 to 5% by mass, preferably 1 to 3% by mass, based on the total amount of the organic solvent in the ink.

The content of the organic solvent in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 60% by mass or less from the viewpoint of ink drying property and ejection reliability. More preferably, it is 20% by mass or more and 60% by mass or less.

<Water>
The content of water in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of ink drying property and ejection reliability, it is preferably 10% by mass or more and 90% by mass or less, and 20% by mass. % To 60% by mass is more preferable.

<Color material>
The coloring material is not particularly limited, and pigments and dyes can be used.
As the pigment, an inorganic pigment or an organic pigment can be used. These may be used alone or in combination of two or more. Moreover, you may use a mixed crystal.
As the pigment, for example, a black pigment, a yellow pigment, a magenta pigment, a cyan pigment, a white pigment, a green pigment, an orange pigment, a glossy color pigment such as gold or silver, a metallic pigment, or the like can be used.
As inorganic pigments, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, carbon black produced by known methods such as contact method, furnace method, and thermal method. Can be used.
Examples of organic pigments include azo pigments and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.). , Dye chelate (for example, basic dye type chelate, acidic dye type chelate, etc.), nitro pigment, nitroso pigment, aniline black and the like can be used. Among these pigments, those having a good affinity with a solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
As a specific example of the pigment, for black, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron (CI pigment black 11) , Metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).
Further, for color, C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmin 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Magenta), 104, 105, 106, 108 ( Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment Violet 1 (Rhodamine Lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3, 15: 4 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment Greens 1, 4, 7, 8, 10, 17, 18, 36, etc.
The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone or two or more types may be used in combination.
As the dye, for example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52,80,82,249,254,289, C.I. I. Acid Blue 9,45,249, C.I. I. Acid Black 1,2,24,94, C.I. I. Hood Black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1,2,15,71,86,87,98,165,199,202, C.I. I. Dilekdo Black 19,38,51,71,154,168,171,195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, 35 can be mentioned.

The content of the coloring material in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass, from the viewpoint of improving image density, good fixability and ejection stability. It is as follows.

In order to disperse the pigment to obtain an ink, a method of introducing a hydrophilic functional group into the pigment to obtain a self-dispersing pigment, a method of coating the surface of the pigment with a resin and dispersing it, and a method of dispersing using a dispersant are used. The method, etc. can be mentioned.
As a method of introducing a hydrophilic functional group into a pigment to obtain a self-dispersing pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon) so that the pigment can be dispersed in water. Can be mentioned.
Examples of the method of coating the surface of the pigment with a resin and dispersing the pigment include a method of encapsulating the pigment in microcapsules so that the pigment can be dispersed in water. This can be rephrased as a resin coating pigment. In this case, it is not necessary that all the pigments blended in the ink are coated with the resin, and the uncoated pigments and the partially coated pigments are dispersed in the ink as long as the effects of the present invention are not impaired. May be.
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low molecular weight dispersant and a high molecular weight dispersant represented by a surfactant.
As the dispersant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant and the like can be used depending on the pigment.
RT-100 (nonionic surfactant) manufactured by Takemoto Oil & Fat Co., Ltd. and a naphthalene sulfonate Na formalin condensate can also be suitably used as a dispersant.
One type of dispersant may be used alone, or two or more types may be used in combination.

<Pigment dispersion>
It is possible to obtain an ink by mixing a material such as water or an organic solvent with a pigment. It is also possible to produce an ink by mixing a material such as water or an organic solvent with a pigment dispersion obtained by mixing a pigment and other water or a dispersant.
The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. It is preferable to use a disperser for dispersion.
The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency is 20 nm or more in terms of the maximum number because the dispersion stability of the pigment is good and the image quality such as ejection stability and image density is also high. It is preferably 500 nm or less, more preferably 20 nm or more and 150 nm or less. The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good ejection stability and increasing the image density, 0.1 mass is used. % Or more and 50% by mass or less are preferable, and 0.1% by mass or more and 30% by mass or less are more preferable.
If necessary, the pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifuge, or the like.

<Resin>
The type of resin contained in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, etc. Examples thereof include resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, and acrylic silicone resins, but urethane resins are preferable from the viewpoint of adhesion. Further, from the viewpoint of enhancing film forming property, adhesion and scratch resistance, it is more preferable to contain at least two kinds of polyurethane resins, and at least two kinds of polyurethane resins having different glass transition temperatures (Tg) are contained. Is particularly preferable.

<< Polyurethane resin particles >>
The polyurethane resin particles contained in the ink are not particularly limited, and examples thereof include polyurethane resin particles obtained by reacting a polyol with polyisocyanate.
Examples of the polyol include polyether polyols, polycarbonate polyols, polyester polyols and the like.

-Polyether polyol-
Examples of the polyether polyol include those obtained by addition polymerization of an alkylene oxide using one or more compounds having two or more active hydrogen atoms as a starting material.
Examples of the starting material include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, glycerin, and trimethylolethane. , Trimethylolpropane and the like. These may be used alone or in combination of two or more.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and tetrahydrofuran. These may be used alone or in combination of two or more.
Examples of the polyether polyol include polyoxytetramethylene glycol and polyoxypropylene glycol from the viewpoint of obtaining an ink binder capable of imparting extremely excellent scratch resistance. These may be used alone or in combination of two or more.

-Polycarbonate polyol-
Examples of the polycarbonate polyol that can be used for producing the polyurethane resin particles include those obtained by reacting a carbonic acid ester with a polyol, and those obtained by reacting phosgene with bisphenol A and the like. These may be used alone or in combination of two or more.
Examples of the carbonic acid ester include methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate and the like. These may be used alone or in combination of two or more.
Examples of the polyol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1, 2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8 − Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcin , Bisphenol-A, bisphenol-F, relatively low molecular weight dihydroxy compounds such as 4,4'-biphenol, polyether polyols such as polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, polyhexamethylene adipate, polyhexamethylene Examples thereof include polyester polyols such as succinate and polycaprolactone. These may be used alone or in combination of two or more.

-Polyester polyol-
Examples of the polyester polyol include those obtained by esterifying a low molecular weight polyol and a polycarboxylic acid, polyester obtained by ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone, and copolymerization thereof. Examples include polyester. These may be used alone or in combination of two or more.
Examples of the low molecular weight polyol include ethylene glycol and propylene glycol. These may be used alone or in combination of two or more.
Examples of the polycarboxylic acid include succinic acid, adipic acid, sebacic acid, dodecandicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, anhydrides or ester-forming derivatives thereof. These may be used alone or in combination of two or more.

-Polyisocyanate-
Examples of the polyisocyanate include aromatic diisocyanates such as phenylenediocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxyli. Examples thereof include aliphatic or alicyclic diisocyanates such as range isocyanate and 2,2,4-trimethylhexamethylene diisocyanate. These may be used alone or in combination of two or more. When the ink used in the present invention is used for outdoor use such as posters and signboards, aliphatic or alicyclic diisocyanates are preferable from the viewpoint of long-term weather resistance.
Further, by using at least one alicyclic diisocyanate, it becomes easy to obtain good coating film strength and scratch resistance.
Examples of the alicyclic diisocyanate include isophorone diisocyanate and dicyclohexylmethane diisocyanate.
The content of the alicyclic diisocyanate is preferably 60% by mass or more with respect to the total amount of the isocyanate compound.

[Manufacturing method of polyurethane resin particles]
In the present invention, the polyurethane resin particles used for the ink can be obtained by a conventionally commonly used production method, and examples thereof include the following methods.
First, an isocyanate-terminated urethane prepolymer is produced by reacting the polyol with the polyisocyanate at an equivalent ratio in which the isocyanate group becomes excessive in the absence of a solvent or in the presence of an organic solvent.
Then, the anionic group in the isocyanate-terminated urethane prepolymer is neutralized with a neutralizing agent if necessary, and then reacted with a chain extender, and finally the organic solvent in the system is removed if necessary. Can be obtained by

Examples of the organic solvent that can be used for producing polyurethane resin particles include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetate esters such as ethyl acetate and butyl acetate; nitriles such as acetonitrile; dimethylformamide. , N-Methylpyrrolidone, N-ethylpyrrolidone and other amides. These may be used alone or in combination of two or more.

Examples of the chain extender include polyamines and other active hydrogen group-containing compounds. These may be used alone or in combination of two or more.
Examples of the polyamine include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazin, isophoronediamine, 4,4'-dicyclohexylmethanediamine, and 1,4-cyclohexane. Diamines such as diamines; Polyamines such as diethylenetriamine, dipropylenetriamine, and triethylenetetramine; Hydradins such as hydrazine, N, N'-dimethylhydrazine, and 1,6-hexamethylenebishydrazine; dihydrazide succinate, dihydrazide adipic acid , Glutarate dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide and other dihydrazides. These may be used alone or in combination of two or more.
Examples of the other active hydrogen group-containing compound include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and hexamethylene glycol. Glycos such as saccharose, methylene glycol, glycerin, sorbitol; phenols such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, hydrogenated bisphenol A, hydroquinone, etc. Kind: Water and the like. These may be used alone or in combination of two or more as long as the storage stability of the ink is not deteriorated.

As the polyurethane resin particles, polycarbonate-based urethane resin particles are preferable from the viewpoints of water resistance, heat resistance, abrasion resistance, weather resistance, and scratch resistance of images due to the high cohesive force of carbonate groups. In the case of the polycarbonate-based urethane resin particles, an ink suitable for a recorded material used in a harsh environment such as outdoor use can be obtained.

As the polyurethane resin particles, a commercially available product can be used, and examples of the commercially available product include the following.
"WBR-016U" (Tg = 20 ° C, manufactured by Taisei Fine Chemicals Co., Ltd.)
"Takelac W-6061" (Tg = 25 ° C, manufactured by Mitsui Chemicals, Inc.)
"Takelac W-6021" (Tg = -60 ° C, manufactured by Mitsui Chemicals, Inc.)
"Takelac WS-5000" (Mitsui Chemicals, Inc. Tg = 65 ° C)
"WBR-2019" (Tg = 45 ° C, manufactured by Taisei Fine Chemicals Co., Ltd.)
"WBR-022U" (Tg = 20 ° C, manufactured by Taisei Fine Chemicals Co., Ltd.)

When the resin particles are copolymers, the Tg of the resin can be controlled by changing the ratio of the monomers forming the copolymer and the polymerization ratio. When the Tg is low, the film-forming property at the time of drying is improved, and when the Tg is high, the scratch resistance is improved.

The volume average particle diameter of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good fixability and high image hardness, 10 nm or more and 1,000 nm or less are preferable. More than 200 nm is more preferable, and 10 nm or more and 100 nm or less is particularly preferable.
The volume average particle size can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The content of the resin is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of fixability and storage stability of the ink, 1% by mass or more and 30% by mass or less with respect to the total amount of the ink. Is preferable, and 5% by mass or more and 20% by mass or less is more preferable.

The particle size of the solid content in the ink is not particularly limited and can be appropriately selected according to the purpose, but from the viewpoint of improving image quality such as ejection stability and image density, the maximum frequency in terms of the maximum number of inks. Is preferably 20 nm or more and 1000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solid content includes resin particles, pigment particles, and the like. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

<Additives>
If necessary, a surfactant, a defoaming agent, an antiseptic / antifungal agent, a rust preventive, a pH adjuster, or the like may be added to the ink.

<Surfactant>
As the surfactant, any of a silicone-based surfactant, a fluorine-based surfactant, an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant can be used.
The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, single-ended modified polydimethylsiloxane, and side chain double-ended modified polydimethylsiloxane. Those having an oxyethylene group and a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. Further, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include a compound in which a polyalkylene oxide structure is introduced into the Si portion side chain of dimethylsiloxane.
Examples of the fluorine-based surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. A polyoxyalkylene ether polymer compound is particularly preferable because it has a low foaming property. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonic acid salt. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salt. The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes 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. The counterions of the salts in these fluorine-based surfactants are 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). _3rd grade can be mentioned.
Examples of the amphoteric tenside agent include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, and lauryldihydroxyethylbetaine.
Examples of the nonionic surfactant include polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, and polyoxyethylene sorbitan. Examples thereof include a fatty acid ester and an ethylene oxide adduct of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, and polyoxyethylene alkyl ether sulfate salt.
These may be used alone or in combination of two or more.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, side chain-modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, one-ended modified polydimethylsiloxane, side. Examples thereof include polydimethylsiloxane modified at both ends of the chain, and a polyether-modified silicone-based surfactant having a polyoxyethylene group and a polyoxyethylene polyoxypropylene group as modifying groups exhibits good properties as an aqueous surfactant, and is particularly effective. preferable.
As such a surfactant, an appropriately synthesized one may be used, or a commercially available product may be used. Commercially available products can be obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd.
The above-mentioned polyether-modified silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a polyalkylene oxide structure represented by the general formula (S-1) is dimethylpoly. Examples thereof include those introduced into the Si portion side chain of siloxane.

一般式（Ｓ−１）

General formula (S-1)

(However, in the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R'represents an alkyl group.)
Commercially available products can be used as the above-mentioned polyether-modified silicone-based surfactant, for example, KF-618, KF-642, KF-643 (Shinetsu Chemical Industry Co., Ltd.), EMALEX-SS-5602, SS- 1906EX (Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Big Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.) and the like can be mentioned.

As the fluorine-based surfactant, a compound having 2 to 16 carbon atoms substituted with fluorine is preferable, and a compound having 4 to 16 carbon atoms substituted with fluorine is more preferable.
Examples of the fluorine-based surfactant include a perfluoroalkyl phosphate compound, a perfluoroalkylethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is preferable because it has low foaming property, and is particularly a fluorine-based compound represented by the general formula (F-1) and the general formula (F-2). Surfactants are preferred.

一般式（Ｆ−１）

General formula (F-1)

In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10, and n is preferably an integer of 0 to 40 in order to impart water solubility.
General formula (F-2)
C _n F _{2n + 1-} CH ₂ CH (OH) CH ₂ −O− (CH ₂ CH ₂ O) _a− Y
In the compound represented by the above general formula (F-2), Y is H or CmF _{2m + 1} and m is an integer of 1 to 6, or CH ₂ CH (OH) CH _2- CmF _{2m + 1} and m is 4 to 6. It is an integer, or CpH _{2p + 1} and p is an integer of 1-19. n is an integer of 1-6. a is an integer of 4 to 14.
Commercially available products may be used as the above-mentioned fluorine-based surfactant. Examples of this commercially available product include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Full Lard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Co., Ltd.); Megafuck F-470, F -1405, F-474 (all manufactured by Dainippon Ink and Chemicals Co., Ltd.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by The Chemours Company); FT-110, FT-250, FT-251, FT-400S, FT-150, FT- 400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omniova), Unidyne DSN-403N (manufactured by Daikin Industries Co., Ltd.) Among these, FS-3100, FS-34, FS- of The Chemours Co., Ltd., from the viewpoint of remarkably improving good print quality, particularly color development, penetrability to paper, wettability, and leveling property. 300, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omniova Co., Ltd. and Unidyne DSN-manufactured by Daikin Industries Co., Ltd. 403N is particularly preferable.

Above all, by adding a silicone-based surfactant, it is possible to promote the spread and penetration of the printed matter into the recording medium. As for the HLB value of the silicone-based surfactant, the lower the value, the higher the penetrating function, but the stability in the ink is affected. Therefore, the HLB value is preferably 8 or more, and more preferably 10 or more.
Here, the HLB value (hydrophilic group / hydrophobic group balance “Hydrophile-Lipophile Balance”) is defined by the following formula (Griffin method).
HLB = 20 × (sum of formulas of hydrophilic part / molecular weight)

Commercially available products can be used as the silicone surfactant, and those having an HLB value of 8 or more include Silface SAG002 (HLB value = 12) and Sylface SAG503A (HLB value = 11) (Nisshin Kagaku Kogyo). , SH-3773M (HLB value = 8.0) (Toray Dow Corning Co., Ltd.), KF-353 (HLB value = 10.0), KF-6011 (HLB value = 14.5), KF -6011P (HLB value = 14.5), KF-6013 (HLB value = 10.0), KF-6004 (HLB value = 9.0) (manufactured by Shin-Etsu Chemical Industry Co., Ltd.) and the like can be mentioned. These may be used alone or in combination of two or more.

The content of the surfactant in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of excellent wettability and ejection stability and improvement in image quality, 0.001 mass is used. % Or more and 5% by mass or less are preferable, and 0.05% by mass or more and 5% by mass or less are more preferable.

The content of the silicone surfactant in the ink is preferably 0.1% by mass or more and 4.0% by mass or less, more preferably 1.0% by mass or more and 2.0% by mass or less, based on the total amount of the ink. When the content is 1.0% by mass or more and 2.0% by mass or less, ink fixability can be ensured even when a non-permeable base material is used as the recording medium to be printed matter, and further, gloss and the like can be obtained. The image quality is also good.

<Defoamer>
The defoaming agent is not particularly limited, and examples thereof include a silicone-based defoaming agent, a polyether-based defoaming agent, and a fatty acid ester-based defoaming agent. These may be used alone or in combination of two or more. Among these, a silicone-based defoaming agent is preferable because it has an excellent defoaming effect.

<Preservatives and fungicides>
The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Rust inhibitor>
The rust preventive is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

<pH adjuster>
The pH adjusting agent is not particularly limited as long as the pH can be adjusted to 7 or more, and examples thereof include amines such as diethanolamine and triethanolamine.

<Cleaning liquid>
The cleaning liquid of the present invention is used for cleaning the nozzle surface of a printing apparatus provided with a nozzle for ejecting ink, and contains the same organic solvent as the organic solvent (1) contained in the ink.
By using the organic solvent (1) contained in the ink, for example, the affinity between the undried ink deposits and the cleaning liquid is improved, and the ink stains adhering to the nozzle surface can be satisfactorily removed.
Examples of the organic solvent (1) include those described in the description of the ink, and among them, 3-methoxy-N and N-dimethylpropionamide are particularly preferable.

The content of the organic solvent (1) in the cleaning liquid of the present invention is 30 to 50% by mass, preferably 35 to 45% by mass, based on the entire cleaning liquid. If the content of the organic solvent (1) is out of the range of 30 to 50% by mass with respect to the entire cleaning liquid, the removability of ink stains adhering to the nozzle surface is inferior, and deterioration of the water repellency of the nozzle surface cannot be reduced. ..

Further, the cleaning liquid of the present invention contains an organic solvent (2) that is not contained in the ink. Above all, the organic solvent (2) is preferably a glycol ether-based organic solvent in consideration of the detergency and stability of the ink flow path and the like, the pullability into the nozzle hole, and the like. Further, by using a glycol ether-based organic solvent, for example, it is possible to secure the solubility (redispersibility) of the cleaning liquid in the dried ink deposits, and it is possible to reduce the deterioration of the water repellency of the nozzle surface. As a result, damage to the nozzle surface can be suppressed.

The glycol ether-based organic solvent (2) is not particularly limited, and for example, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, and diethylene glycol dibutyl ether. , Diethylene glycol methyl ethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, propylene glycol n-propyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether. , Tripropylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, glycol ethers such as tetraethylene glycol diethyl ether and the like. Among these, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, and diethylene glycol methyl ethyl ether are preferable, and diethylene glycol diethyl ether is particularly preferable.

The content of the organic solvent (2) in the cleaning liquid of the present invention is 10 to 20% by mass, preferably 12 to 18% by mass, based on the entire cleaning liquid. If the content of the organic solvent (2) is out of the range of 10 to 20% by mass with respect to the entire cleaning liquid, the removability of ink stains adhering to the nozzle surface is inferior, and deterioration of the water repellency of the nozzle surface cannot be reduced. ..

The content of all the organic solvents contained in the cleaning liquid of the present invention is 50 to 70% by mass, preferably 53 to 60% by mass, based on the entire cleaning liquid. When the content of all the organic solvents contained in the cleaning liquid of the present invention is 50% by mass or more, the removability of ink stains adhering to the nozzle surface is enhanced, and when it is 70% by mass or less, the nozzle surface is damaged. Can be suppressed, and the influence on the wiping member and other members used for cleaning the nozzle surface, which will be described below, can be suppressed.

Further, the cleaning liquid of the present invention preferably contains a surfactant, and more preferably a polyalkylene glycol-based surfactant, in consideration of stability, pullability into the nozzle hole, and the like. Commercially available polyalkylene glycol-based surfactants can be used, for example, Emargen LS-106 (manufactured by Kao Corporation), Emargen LS-110 (manufactured by Kao Corporation), Softanol EP7025 (Nippon Shokubai Co., Ltd.). Made) and the like.
The content of the surfactant in the cleaning liquid of the present invention is preferably 0.5 to 5.0% by mass, more preferably 1 to 3.0% by mass, based on the entire cleaning liquid.

Further, the cleaning liquid of the present invention may be used in combination with a polyol compound having 8 to 11 carbon atoms, for example, for the purpose of controlling the permeability to a dry ink film. Specific examples include, for example, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol and the like.

<Recording device, recording method>
The ink of the present invention can be suitably used for various recording devices by an inkjet recording method, for example, a printer, a facsimile device, a copying device, a printer / fax / copier multifunction device, a three-dimensional modeling device, and the like.
In the present invention, the recording device and the recording method are devices capable of ejecting ink, various processing liquids, and the like to a recording medium, and a method of recording using the device. The recording medium means a medium to which ink and various treatment liquids can adhere even temporarily.
This recording device can include not only a head portion for ejecting ink, but also means related to feeding, transporting, and discharging paper of a recording medium, and other devices called pretreatment devices and posttreatment devices. ..
The recording device and recording method may include a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, means for heating and drying the print surface and the back surface of the recording medium. The heating means and the drying means are not particularly limited, but for example, a hot air heater and an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like.
Further, the recording device and the recording method are not limited to those in which significant images such as characters and figures are visualized by ink. For example, those that form patterns such as geometric patterns and those that form a three-dimensional image are also included.
Further, the recording device includes both a serial type device that moves the discharge head and a line type device that does not move the discharge head, unless otherwise specified.
Further, as this recording device, it is possible to use not only a desktop type but also a wide recording device capable of printing on an A0 size recording medium, or, for example, continuous paper wound in a roll shape as a recording medium. A continuous line printer is also included.
An example of the recording device will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank. The image forming apparatus 400 as an example of the recording apparatus is a serial type image forming apparatus. A mechanical unit 420 is provided in the exterior 401 of the image forming apparatus 400. Each ink storage section 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is, for example, a package of an aluminum laminated film or the like. It is formed of members. The ink container 411 is housed in, for example, a plastic container case 414. As a result, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided behind the opening when the cover 401c of the apparatus main body is opened. A main tank 410 is detachably attached to the cartridge holder 404. As a result, each ink ejection port 413 of the main tank 410 and the ejection head 434 for each color communicate with each other via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 to the recording medium.
In addition, image formation, recording, printing, printing, etc. in the terms of the present invention are all synonymous.

(Washing method)
The cleaning method of the present invention is a method of cleaning a nozzle surface for ejecting ink in a recording device as described above, and has a cleaning step of bringing the nozzle surface into contact with the cleaning liquid of the present invention. By this cleaning step, ink stains adhering to the nozzle surface can be satisfactorily removed, deterioration of water repellency of the nozzle surface can be reduced, and damage to the nozzle surface can be suppressed.
Specifically, the cleaning step is a step of wiping the nozzle surface with a wiping member soaked with the cleaning liquid of the present invention, or after the nozzle surface and the cleaning liquid of the present invention are brought into contact with each other by, for example, a spray. , The step can be a step of wiping the nozzle surface with a wiping member.
As the wiping member, a known member can be used, and examples thereof include a non-woven fabric. Further, as is well known, the nozzle surface is a surface on which a nozzle opening of a nozzle for ejecting ink is formed.

The printing apparatus of the present invention comprises a cleaning means for cleaning the nozzle surface by bringing the nozzle surface for ejecting ink in the recording apparatus as described above into contact with the cleaning liquid of the present invention.
Specifically, the cleaning means is a wiping member soaked with the cleaning liquid of the present invention, and the nozzle surface is wiped and cleaned by the wiping member, or the nozzle surface and the cleaning liquid of the present invention are cleaned. The nozzle surface can be wiped and cleaned by the wiping member after the nozzles are brought into contact with each other by, for example, a spray.
As the wiping member, a known member can be used, and examples thereof include a non-woven fabric.

Here, FIG. 3 is a schematic view showing an example of cleaning means in the printing apparatus of the present invention. The cleaning means 300 of FIG. 3 is a device for cleaning the nozzle surface 301a on the ink ejection side of the nozzle plate 301 of the ink ejection head.
The cleaning means 300 includes a non-woven fabric 303 as a wiping member, a cleaning liquid applying nozzle 302 as a cleaning liquid applying means, a pressing roller 305 as a pressing member, and a winding roller 304 for winding the non-woven fabric after the wiping treatment. There is.
The cleaning liquid is supplied from the cleaning liquid tank via a cleaning liquid supply tube (not shown). By driving a pump provided in the middle of the cleaning liquid supply tube, the cleaning liquid is applied to the non-woven fabric 303 as the wiping member from the cleaning liquid application nozzle 302 in an amount of the cleaning liquid applied according to the recording time. The non-woven fabric 303 is wound in a roll shape.
Then, as shown in FIG. 3, the non-woven fabric 303 to which the cleaning liquid is applied is brought into contact with the nozzle surface 301a of the ink ejection head 301 by the pressing roller 305 as a pressing member and pressed, so that the nozzle surface 301a is cleaned. After the wiping process is completed, the non-woven fabric 303 is wound by the winding roller 304.
A plurality of cleaning liquid application nozzles 302 as cleaning liquid application means can be provided, and pressure is applied based on the control of the control means (not shown). By appropriately changing the pressure, the amount of cleaning liquid applied can be increased. Can be adjusted. Further, based on the control of the control means (not shown), the amount of the cleaning liquid applied can be adjusted by changing the number of nozzles to which the cleaning liquid is applied. Further, the amount of the cleaning liquid applied can be adjusted by changing the number of times the cleaning liquid is applied based on the control of the control means (not shown).
In this way, the nozzle surface during or after recording may be wiped using the wiping member to which the cleaning liquid is applied.
In the above description, an example using the non-woven fabric 303 soaked with the cleaning liquid has been described. Separately, after the cleaning liquid is brought into contact with the nozzle surface 301a by spraying or the like (not shown), the nozzle surface 301a is wiped with the non-woven fabric 303. You may.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to the following examples. In addition, in this Example, a part means a mass part.

Example 1
<Preparation of polymer solution>
After replacing the inside of a 1 L flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas introduction tube, a reflux tube and a dropping funnel with nitrogen gas, 11.2 g of styrene, 2.8 g of acrylic acid, 12 g of lauryl methacrylate, and polyethylene glycol methacrylate were used. 4 g, 4 g of styrene macromer, 0.4 g of mercaptoethanol and 40 g of methyl ethyl ketone were added, and the temperature was raised to 65 ° C. Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108 g of lauryl methacrylate, 36 g of polyethylene glycol methacrylate, 60 g of hydroxylethyl methacrylate, 36 g of styrene macromer, 3.6 g of mercaptoethanol, 2.4 g of azobismethylvaleronitrile and 342 g of methyl ethyl ketone. The mixed solution was added dropwise into the flask over 2.5 hours. Further, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was added dropwise to the flask over 0.5 hours, and then aged for 1 hour. Next, 0.8 g of azobismethylvaleronitrile was added and then aged for 1 hour to obtain 800 g of a 50 mass% polymer solution.

<Preparation of magenta pigment dispersion>
28 g of polymer solution, 26 g of C.I. I. Pigment Red 122, 13.6 g of a 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone and 13.6 g of water were stirred and then kneaded using a roll mill. The obtained paste is put into 200 g of water and stirred, and then methyl ethyl ketone and water are distilled off using an evaporator to contain a magenta pigment having a pigment content of 15% by mass and a solid content of 20% by mass. An aqueous dispersion of resin was obtained.

<Preparation of magenta pigment ink>
The following components were mixed to make a total of 100 parts.
M-100 (Equamid) (manufactured by Idemitsu Kosan Co., Ltd.) 20 parts 1,2-propanediol 10 parts Silface SAG002 (HLB value = 12) (manufactured by Nissin Chemical Co., Ltd.) 1 part Polyurethane resin SF150HS (Tg = 32 ° C) (Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) (By solid content) 4 parts Polyurethane resin W-6021 (Tg = -60 ° C) (Mitsui Chemicals Co., Ltd.) (By solid content) After stirring 3 parts for 1 hour,
After adding the water residue of 40 parts of the magenta pigment dispersion and stirring for 1 hour, pressure filtration was performed using a polypropylene filter having a pore size of 1.5 μm to remove coarse particles to obtain a magenta pigment ink.

<Preparation of cleaning solution>
The components below the cleaning solution of Example 1 were mixed to make a total of 100 parts.
M-100 (Equamid) (manufactured by Idemitsu Kosan Co., Ltd.) 42 parts Diethylene glycol diethyl ether 10 parts Emargen LS106 (manufactured by Kao Corporation) 1 part The water residue was mixed to obtain a cleaning solution 1.

Examples 2-5 and Comparative Examples 1-4
Based on the formulations shown in Table 1 below, various cleaning solutions were obtained in the same manner as in Example 1.

Description of each component Equamid M-100: 3-Methoxy-N, N-dimethylpropionamide (manufactured by Idemitsu Kosan Co., Ltd.)
LS106: Emargen LS-106 (manufactured by Kao Corporation) (polyalkylene glycol-based surfactant)
LS110: Emargen LS-110 (manufactured by Kao Corporation) (polyalkylene glycol-based surfactant)
EP7025: Softanol EP7025 (manufactured by Nippon Shokubai Co., Ltd.) (polyalkylene glycol-based surfactant)
WET-240: WET-240 (manufactured by Evonik) (silicone-based surfactant)
FS300: Zonir FS-300 (manufactured by DuPont) (fluorine-based surfactant)

The following evaluations were carried out for each of the obtained cleaning liquids.

<Evaluation of wiping wipeability>
The magenta pigment ink prepared above was spray-coated on the nozzle surface, dried at 50 ° C. for 24 hours, and then a constant load was applied to a non-woven fabric (Anticon) moistened with a cleaning solution to wipe the nozzle surface. The number of wipes required to run out of dry ink on the surface was measured.

<Nozzle surface water repellency evaluation>
The water repellency of the nozzle surface was determined by immersing the nozzle surface in contact with each cleaning liquid at 50 ° C. for 1 week and determining the contact angle with respect to the ink before and after immersion. The contact angle was calculated by using the contact angle meter OCA-G200 of Eiko Seiki, dropping 5 μl of the magenta pigment ink prepared above onto the nozzle surface, reading the contact angle 1 second later, and calculating the amount of decrease in contact angle due to immersion. ..
Judgment criteria are as follows: ○: Decrease is 0 ° or more and less than 15 ° Δ: Decrease is 15 ° or more and less than 25 ° ×: Decrease is 25 ° or more

The results are shown in Table 2 below.

From the results in Table 2, the cleaning liquids prepared in each example can satisfactorily remove ink stains adhering to the nozzle surface, reduce deterioration of water repellency on the nozzle surface, and suppress damage to the nozzle surface. There was found.
On the other hand, in Comparative Example 1, since the content of all the organic solvents contained in the cleaning liquid was less than the lower limit specified in the present invention, the wiping wipeability evaluation was deteriorated. In Comparative Example 2, since the contents of all the organic solvents contained in the cleaning liquid exceeded the upper limit specified in the present invention, the evaluation of water repellency on the nozzle surface deteriorated. In Comparative Example 3, since the content of the organic solvent (1) in the cleaning liquid exceeds the upper limit of the present invention and the cleaning liquid does not contain the organic solvent (2), both the wiping wipeability evaluation and the nozzle surface water repellency evaluation deteriorate. did. In Comparative Examples 4 and 5, since the cleaning liquid did not contain the organic solvent (1), both the wiping wipeability evaluation and the nozzle surface water repellency evaluation could not be satisfied.

300 Cleaning means 301 Nozzle plate 301a Nozzle surface 302 Cleaning liquid application nozzle 303 Wiping member (non-woven) 304 Winding roller 305 Pressing roller 400 Image forming device 401 Image forming device exterior 401c Device body cover 404 Cartridge holder 410 Main tank 410k, 410c , 410m, 410y Black (K), Cyan (C), Magenta (M), Yellow (Y) Main tank 411 Ink storage unit 413 Ink outlet 414 Storage container case 420 Mechanical unit 434 Discharge head 436 Supply tube

Japanese Patent No. 5402978

Claims (11)

A cleaning liquid that cleans the nozzle surface of a printing device equipped with a nozzle that ejects ink.
When the organic solvent contained in the ink is the organic solvent (1),
The cleaning liquid contains the same organic solvent as the organic solvent (1) contained in the ink, and contains the same organic solvent.
The content of the organic solvent (1) in the cleaning liquid is 30 to 50% by mass with respect to the entire cleaning liquid.
The cleaning liquid contains an organic solvent (2) that is not contained in the ink.
The content of the organic solvent (2) in the cleaning liquid is 10 to 20% by mass with respect to the entire cleaning liquid, and the content of all the organic solvents contained in the cleaning liquid is 50 to 70 with respect to the entire cleaning liquid. % by mass it is,
The organic solvent (1) is 3-methoxy-N, N-dimethylpropionamide.
A cleaning liquid characterized in that the organic solvent (2) is a glycol ether-based organic solvent. The first aspect of claim 1, wherein the glycol ether-based organic solvent is selected from diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, and triethylene glycol monopropyl ether. Cleaning solution. The cleaning solution according to claim 1 or 2 , wherein the cleaning solution further contains a surfactant, and the surfactant is a polyalkylene glycol-based surfactant. A cleaning method for cleaning the nozzle surface of a printing device equipped with a nozzle for ejecting ink.
A cleaning method comprising a cleaning step of bringing the nozzle surface into contact with the cleaning liquid according to any one of claims 1 to 3 to clean the nozzle surface. The cleaning method according to claim 4 , wherein the cleaning step is a step of wiping the nozzle surface with a wiping member soaked with the cleaning liquid according to any one of claims 1 to 3. The cleaning step, and the nozzle surface, after contacting the cleaning solution according to any one of claims 1 to 3, the wiping member to claim 4, characterized in that the step of wiping the nozzle face The cleaning method described. A printing device equipped with a nozzle that ejects ink.
A printing apparatus comprising a cleaning means for cleaning the nozzle surface by bringing the nozzle surface of the printing apparatus into contact with the cleaning liquid according to any one of claims 1 to 3. The printing according to claim 7 , wherein the cleaning means is a wiping member soaked with the cleaning liquid according to any one of claims 1 to 3 , and the nozzle surface is wiped and cleaned by the wiping member. apparatus. The cleaning means is a wiping member, and after the nozzle surface is brought into contact with the cleaning liquid according to any one of claims 1 to 3 , the nozzle surface is wiped and cleaned by the wiping member. 7. The printing apparatus according to claim 7. The printing apparatus according to any one of claims 7 to 9 , wherein the ink contains at least two kinds of polyurethane resins. The printing apparatus according to claim 10 , wherein the ink contains at least two kinds of polyurethane resins having different glass transition temperatures (Tg).

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