JP5618250B2 - Cleaning liquid for inkjet apparatus and cleaning method for inkjet recording apparatus - Google Patents

Description

  The present invention relates to a cleaning liquid for an ink jet recording apparatus and a method for cleaning an ink jet recording apparatus using the same.

  In general, a printer, a fax machine, a copier, a plotter, or an image forming apparatus that combines a plurality of these functions includes, for example, a recording head composed of a liquid ejection head that ejects ink droplets, and conveys a medium. However, there are some which perform image formation by attaching ink droplets to paper. In such a liquid ejection type image forming apparatus, it is possible to form a pattern in a non-contact manner on a medium by ejecting liquid droplets from a number of pores called many nozzles of a liquid ejection head. Therefore, it is possible to form an image by a single image forming process regardless of the type and shape of the medium.

This liquid discharge head includes a nozzle portion having a fine orifice having a diameter of 50 μm or less, a pressure generating portion connected to the nozzle portion, a liquid chamber portion for supplying liquid to the pressure generating portion, and a filter portion for filtering the liquid flowing into the liquid chamber Etc., and processed and formed with very high accuracy.
In addition, since the number of nozzles per head is enormous, from several tens to several thousand, the entire system operates normally before shipping as a product. It is necessary to make sure that there is no state in which the ejected droplet cannot form a desired size.

  In order to perform such an inspection, a defect is detected by filling the head with a detectable liquid and discharging the liquid from the head. Further, in order to prevent the ink filled in the head and the ink supply system from leaking to the outside due to repair or the like, the ink in the inkjet apparatus needs to be washed away.

Conventionally, water alone, an aqueous surfactant solution, and the like have been used. However, these can ensure cleanability, but there are problems such as deterioration in filling property during refilling and occurrence of defective discharge. It was.
More recently, inks using pigments as colorants have been put into practical use from the viewpoint of water resistance and light resistance. In the case of using a dye, from the same viewpoint, there is a tendency to increase the dye concentration or use a low water solubility, and the above problem has become more prominent.

In particular, in the case of using a pigment or a resin, if even a small amount of ink in the head remains, the ink is fixed and the dischargeability is lowered. Therefore, for example, Patent Documents 1 and 2 propose adding a resin solvent to the maintenance liquid. In this case, the maintenance liquid has a function of dissolving and redispersing the residual solid content even when the ink is dried.
However, the solvents described in the above-mentioned patent documents have a risk of causing the adhesive surface to swell by giving solubility to the adhesive used in the head. For this reason, there is a problem in that the strength of the head is lowered, the desired rigidity cannot be obtained, and the intended ejection property cannot be obtained.

  In consideration of the cleanability and storage stability of the apparatus, a cleaning liquid using an ethindiol nonionic surfactant as described in Patent Document 3 has also been proposed. However, the cleaning liquid has a low foaming property, but is less soluble in water than a general alkyl alcohol nonionic surfactant and has a low ability to lower the surface tension, so that the cleaning power is insufficient.

In view of the cleanability in the apparatus, a method using a polyoxyalkylene secondary alcohol ether as described in Patent Document 4 has been proposed. By using such a surfactant, it is possible to increase the detergency.
However, only the configuration described in Patent Document 4 may cause minute corrosion to the metal member, and the deterioration of the durability of the head or the like is a problem due to the corrosion. There is disclosed a filling liquid as described in Patent Document 5 to which a corrosion inhibitor that prevents such elution of metal members and can be washed and stored is added. However, coexistence with detergency was not sufficient.

  In recent years, microemulsion type pigments in which a pigment surface is coated with a poorly water-soluble resin have been developed as pigment dispersions with improved color development and fixing properties, which are excellent in color development and fixing properties. However, the dispersion stability is inferior to that of a self-dispersing pigment having a dispersion functional group covalently bonded to the pigment surface, and the redispersibility after drying is deteriorated. In addition, since the functional group is not bonded by a covalent bond, it is greatly affected by the environment around the pigment, and is likely to cause aggregation due to temperature, pH, solvent composition, vehicle organicity, and the like.

  These tend to have the same tendency even after the inkjet head is washed with a washing liquid. Compared to a self-dispersing pigment, a pigment whose surface is coated with a poorly water-soluble resin has poor dispersion stability in the liquid after washing. There is a tendency.

  The object of the present invention is to sufficiently clean the ink flow path even in the case of a pigment ink using a pigment whose surface is coated with a poorly water-soluble resin, and does not cause a problem in ink refillability after cleaning. To provide a cleaning liquid for an ink jet recording apparatus and a cleaning method using the same.

(1) Inkjet recording that cleans the flow path of an inkjet recording apparatus that uses ink containing at least colored resin particles containing water-insoluble or hardly soluble colorant in resin particles, a water-soluble organic solvent, and water. A cleaning solution for the device,
The cleaning liquid contains at least water, a water-soluble organic solvent, and a polyoxyalkylene monoalkyl ether represented by the following general formula (1),
The viscosity of the cleaning liquid at 25 ° C. is 2.5 mPa · s or more,
A cleaning liquid for an ink jet recording apparatus, comprising at least glycerin as a water-soluble organic solvent in the cleaning liquid, wherein a content of the glycerin is 4% by mass or more and 20% by mass or less with respect to the cleaning liquid.
(2) A flow path of an ink jet recording apparatus using ink containing colored fine particles containing at least CI Pigment Red 122 or CI Pigment Yellow 74 as a colorant is washed. The cleaning liquid for an ink jet recording apparatus according to the above (1).
(3) The cleaning liquid for an ink jet recording apparatus according to (1) or (2), wherein the cleaning liquid has a viscosity at 25 ° C. of 15 mPa · s or less.
(4) The water-soluble organic solvent includes 1,3-butanediol and / or 3-methyl-1,3-butanediol, as described in any one of (1) to (3) above Cleaning liquid for inkjet recording apparatus.
(5) The ink-jet recording apparatus in which the ink supply path is filled with ink is passed through the ink-jet recording apparatus cleaning liquid according to any one of (1) to (4) to replace the liquid. Ink jet recording apparatus cleaning method.
(6) In the above (5), the step of supplying and discharging the cleaning liquid into the ink flow path of the ink jet recording apparatus is repeated until the concentration of the colored fine particles in the discharged liquid becomes 5 mass% or less. A method for cleaning an ink jet recording apparatus according to claim 1.

  According to the present invention, it is possible to provide a cleaning liquid for an ink jet recording apparatus that can sufficiently clean an ink flow path and does not cause a problem in ink refillability after cleaning, and a method for cleaning an ink jet recording apparatus. The present invention is highly effective for an ink jet recording apparatus using a pigment ink using a pigment whose surface is coated with a poorly water-soluble resin.

  The present invention is a cleaning liquid for an ink jet apparatus for cleaning a flow path of an ink jet recording apparatus using an ink composed of a colored resin fine particle containing a water-insoluble or hardly soluble coloring material in a resin fine particle, a water-soluble organic solvent, and water, A cleaning liquid for an ink jet apparatus comprising at least water, a water-soluble organic solvent, and a polyoxyalkylene monoalkyl ether represented by the following general formula (1).

  When the ink in the ink jet recording apparatus uses colored resin fine particles in which the resin fine particles contain a water-insoluble or hardly soluble color material as the color material, the ink is extremely diluted with the cleaning liquid after the head cleaning. As a result, the environment around the pigment has changed significantly, making it difficult to maintain dispersion stability.

The cleaning liquid of the present invention uses a polyoxyalkylene monoalkyl ether using an alkyl alcohol having no branch as described above, so that the penetrating power mixed with the ink in the flow path in the inkjet head and the ink after mixing with the ink It is possible to have a dispersion force capable of maintaining the dispersion state of the pigment in the interior. Furthermore, since the foaming property and defoaming property are appropriately suppressed, it is possible to show the cleaning property and the storage property without affecting the bubbles in the ink jet apparatus.
A surfactant having an unbranched alkyl chain is excellent in biodegradability, and has the advantage of reducing the environmental burden during environmental discharge.

  In addition, the penetrating power and detergency of the surfactant largely depend on the structure of the surfactant. Polyoxyalkylene ethers of alkyl alcohols with no branching are excellent in penetrating power and detergency. Among them, when the cloud point is 40 ° C. or lower, the penetrating power is excellent, and the detergency is further improved.

  For such a cleaning liquid, a low-viscosity product has a high flow rate in the head and a high mixing property with ink. However, when there are a large number of nozzles as in an inkjet head, cleaning unevenness is likely to occur unless ink is uniformly removed from each nozzle. When a cleaning liquid having a viscosity lower than that of ink is replaced with ink and flows through the individual liquid chambers in the head, the fluid resistance is lower than that of the other liquid chambers, so that more cleaning liquid flows more easily than the other liquid chambers. For this reason, the nozzles that have been replaced with the cleaning liquid are easy to flow, and the remaining nozzles are difficult to flow, and the nozzles cannot be completely cleaned.

Therefore, it is preferable for cleaning the inside of the head that the physical properties of the cleaning liquid are close to those of the ink. When the viscosity at 25 ° C. of the cleaning liquid for an inkjet apparatus is 2.5 mPa · s or more, the viscosity difference from the ink in the head can be reduced, and the head can be cleaned uniformly.
Moreover, when the liquid viscosity is higher, the precipitation of the pigment dispersion when mixed with the pigment ink can be suppressed, and the mixing stability can be improved. However, if the viscosity is too high, it is not preferable because it is separated from the physical properties of the ink. On the other hand, if the viscosity is too high, the flow rate of the liquid is lowered, so that the washing performance is lowered, and the washing time and the amount of washing waste liquid may be increased. In particular, even in the cleaning liquid of the present invention, if the viscosity exceeds 18 mPa · s, the cleaning property may be deteriorated. For this reason, it is preferable that it is 18 mPa * s or less, and it is more preferable that it is 15 mPa * s or less. A particularly preferable result is obtained when the viscosity is 2.5 mPa · s or more and 15 mPa · s or less.

  Further, a water-soluble organic solvent having moisture retention is used as the organic solvent, and it is desirable to use glycerin having high moisture retention and good compatibility with water. However, the colored resin fine particles obtained by adding a water-insoluble or hardly soluble coloring material to the resin fine particles have a glycerin ratio of 20% by mass or less because the dispersion stability decreases when the hydrophilicity becomes too high. On the other hand, if the ratio of glycerin is lowered, the water retention capacity of the liquid is lost. For this reason, in order to maintain moisture retention, the glycerin concentration needs to be 4% by mass or more.

  Such a cleaning liquid has a greater effect on pigment inks using more unstable pigments. For example, as colored resin fine particles obtained by adding a water-insoluble or hardly soluble color material to resin fine particles, those using CI Pigment Red 122, CI Pigment Yellow 74 as a color material include a pigment and a resin. Insufficient adhesion results in an unstable pigment dispersion. The cleaning liquid of the present invention improves the reliability of standing because the cleaning liquid is excellent in dispersion stability even when an ink jet recording apparatus filled with ink using such a pigment is cleaned.

Hereinafter, each composition will be described in detail.
<Cleaning liquid>
As a cleaning liquid for an ink jet apparatus, a function of cleaning an ink flow path of the ink jet apparatus and flushing the ink is required. In order to clean the ink flow path, it is required to separate the ink component from the ink flow path while mixing and replacing with ink. At this time, it is required that the ink flow path member is not deteriorated by the cleaning liquid.

  Moreover, since a large amount of liquid and time are required to completely replace the state after cleaning with the cleaning liquid, the efficiency is poor. Therefore, it is necessary to maintain the quality of the ink jet apparatus even if the ink is replaced to a certain density. If the cleaning liquid does not match the ink, the ink remaining in the cleaning liquid aggregates and is attracted to the nozzles and filters of the inkjet head, causing ejection failure and increased resistance. Therefore, it is required that the liquid physical properties be stable even when the ink and the cleaning liquid are mixed.

  Further, by satisfying the cleaning property and the mixing property with the ink, the refillability can be ensured when the ink is newly filled.

<Surfactant>
In the present invention, by containing at least water and the polyoxyalkylene monoalkyl ether represented by the following general formula (1) as a surfactant, the cleaning property is excellent, the aggressiveness to the ink flow path is low, and the refilling property is high. A cleaning solution can be obtained.

  The content of the polyoxyalkylene monoalkyl ether represented by the general formula (1) is preferably 0.1 to 10% by mass, more preferably 0.3 to 3.0% by mass. When the content is lower than 0.1% by mass, the cleaning effect is reduced. When the content is higher than 10% by mass, the viscosity of the cleaning liquid itself becomes too high, which causes problems such as cleaning properties, bubbles / defoaming properties, and wettability.

  In general formula (1), hydrophobicity and hydrophilicity can be controlled by changing the values of m, x, and y. Increasing m increases the length of the alkyl portion and tends to be hydrophobic, increasing x increases the length of the oxyethylene portion and tends to be hydrophilic, and increasing y increases the length of the oxypropylene portion and tends to be hydrophobic. Further, the characteristics are changed by changing the ratio of x and y. When y is increased, the foam stability is lowered and the foaming and defoaming properties are improved. Moreover, since the waxing of the surfactant in a low temperature state is suppressed, handling as a surfactant is improved.

  As a cleaning liquid for an inkjet device, those having an HLB of 10 to 13 are preferable, and those having x = 6 to 15 and y = 1 to 5 are more preferable. A product with an HLB of less than 10 has a low cloud point and poor solubility at room temperature, so that it cannot exhibit performance. Further, since the surfactant is precipitated from the cleaning liquid when the temperature rises in the storage environment after cleaning, there is a problem that the dispersion state of the pigment dispersion of the ink contained in the cleaning residual liquid is deteriorated to promote aggregation. On the other hand, if the HLB exceeds 13, the hydrophilicity of the surfactant becomes too high and the penetrating power is lowered. Therefore, it is considered that the cleaning effect is lowered because the ink attached to the ink flow path cannot be penetrated.

  If the oxyethylene chain length x is less than 6, the oxypropylene chain y will be 1 or less in order to obtain optimum permeability. Therefore, the main structure becomes a surfactant that does not contain an oxypropylene chain, and there is a problem that the bubbles of the liquid are easily formed and difficult to disappear. When x exceeds 15, the molecular weight of the surfactant becomes too large, so that the penetrating power is lowered and the detergency is lowered. In addition, since the dynamic surface tension in a short cycle is lowered, it is not possible to provide wettability at a place where the flow velocity is fast, and the cleaning property and filling property are insufficient.

  This surfactant is characterized by the fact that the hydrophobic group R is linear, and since it is linear, the permeability is slightly inferior to that of a branched chain, but the stability of micelles formed in solution is Therefore, for some pigment dispersions, dispersion of the pigment is aided and dispersion stability is improved. In addition, when colored fine particles containing finely soluble coloring material in resin fine particles are used as the coloring material, if the surfactant has high permeability, the resin penetrates into the resin and softens the resin, resulting in poorly soluble When the resin is easily peeled from the color material and the resin is peeled off, the color material is aggregated. The surfactant having no branched chain in the hydrophobic group R is highly stable with respect to the colored resin fine particles obtained by adding a water-insoluble or hardly soluble coloring material to the resin fine particles, and is placed in a mixed state with the ink for a long time. However, it is possible to suppress ejection failure caused by the ink color material.

  The length of the straight chain is preferably 3 or more. If the ratio is less than 3, the hydrophobicity is insufficient, so that it is necessary to increase the ratio of the oxypropylene chain, and the permeability is lowered, so that the detergency is insufficient. Further, when m is 16 or more, the hydrophobicity becomes too strong, so that the balance with hydrophilicity increases, the oxyethylene chain increases, the surfactant molecular weight becomes too large, the dynamic surface tension decreases, The wettability in the place where it is early decreases.

  In addition, when using colored resin fine particles in which water-insoluble or hardly soluble color material is contained in the resin fine particles as the color material, the state after the head cleaning is a state in which the ink is extremely diluted with the cleaning liquid, The environment has changed significantly, making it difficult to maintain dispersion stability.

By using polyoxyalkylene monoalkyl ether using such an unbranched alkyl alcohol, the penetrating power that mixes with the ink in the flow path in the inkjet head and the dispersion state of the pigment in the ink after mixing with the ink It is possible to have a dispersion force that can be held. Furthermore, since the foaming property and defoaming property are appropriately suppressed, it is possible to show the cleaning property and the storage property without affecting the bubbles in the ink jet apparatus.
In addition, since it has an unbranched alkyl chain, it is highly biodegradable, reducing the risk of soil contamination during environmental discharge.

  Such surfactants are Emulgen LS-106, LS-110, LS-114, MS-110 manufactured by Kao Corporation, Leox CL2008 manufactured by Lion Corporation, WONDERSURF 80, 100, 140 manufactured by Aoki Oil & Fat Co., Ltd. Oil Co., Ltd. Uniloop 50MB-11, 50MB-26, 50MB-72, 50MB-168, Nonion A-10R, A-13P, A-25B, Unisafe 5P-4, 5P-8, 10P-4, 10P-8 , 20P-4, 20P-8 and other surfactant manufacturers.

<Water-soluble organic solvent>
As the water-soluble organic solvent, by adding a solvent that easily hydrogen bonds, has a high viscosity by itself, has a high equilibrium water content, and decreases in viscosity in the presence of water, Can be obtained.

  Such polyhydric alcohols include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol. 3-methyl-1,3-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4- Examples thereof include butanetriol and 1,2,6-hexanetriol. In particular, glycerin is preferably contained in the cleaning liquid and ink in terms of excellent water retention and moisture retention.

The proportion of the water-soluble organic solvent in the entire cleaning liquid is 20 to 60% by mass within the range where the effects of the present invention can be obtained, and particularly preferably 30 to 50% by mass. If the amount of the water-soluble organic solvent is small, the water retention capacity of the cleaning liquid is reduced, and drying during storage tends to proceed. If the amount of the water-soluble organic solvent is too large, the viscosity of the ink becomes high, which is not preferable because the filling property to the head is lowered and the ink flammability is increased.
In addition, depending on the characteristics of the water-soluble organic solvent, the moisturizing power and the organicity vary greatly. In particular, glycerin has high moisture retention and is added to inks and cleaning liquids for inkjet applications.

  In general, glycerin has a high moisture retention and is known as a highly hydrophilic solvent. Therefore, there is an effect in suppressing the dispersion breakage of the pigment dispersion due to drying. However, in the case where colored resin fine particles obtained by adding water-insoluble or hardly soluble color material to the resin fine particles are used, if the ratio of glycerin is too high, the dispersion stable state is deteriorated.

  Such a deterioration of the dispersion stability state is not clearly understood, but it is assumed that the resin fine particles dispersed are swollen depending on the organic property of the dispersion solvent. The resin fine particles have an amphipathic property between the coloring material and the dispersion solvent, but are designed to increase resistance to the organic solvent used in the ink. As the water-soluble organic solvent used in the ink, a solvent having a slightly higher lipophilicity in terms of imparting a penetrating function is used. Therefore, the resin is designed to withstand these solvents. When the ratio of glycerin is increased, the hydrophilicity is improved and the hydrophilicity of the dispersion solvent is increased. Therefore, it is considered that the dispersion solvent is different from the resistance of the resin, the affinity to the resin is improved, the resin is easily swollen with respect to the dispersion medium, and the dispersion stability is lowered.

  If the amount of glycerin added exceeds 20% by mass with respect to the cleaning liquid, the organicity of the cleaning liquid is excessively lowered, so that it is 20% by mass or less, and the resin fine particles are colored by adding a water-insoluble or hardly soluble colorant. It is desirable to use in combination with ink using resin fine particles as a color material. Moreover, in order to ensure the water retention power of the washing | cleaning liquid by glycerol as mentioned above, it is required that it is 4 mass% or more.

<Additives>
Other additives to be added to the cleaning liquid include, but are not limited to, antiseptic / antifungal agents, pH adjusters, chelating agents, rust inhibitors, and the like.
As the antiseptic / antifungal agent, sodium dehydroacetate, sodium sorbate, 2-pyridinethiol 1-oxide sodium, sodium benzoate, sodium pentachlorophenol and the like can be used in the present invention.

As the pH adjuster, any substance that does not adversely affect the cleaning liquid to be prepared and does not damage the ink flow path of the ink jet device and can adjust the pH to a desired value can be used. Can be used.
Examples thereof include amines, alkali metal hydroxides, quaternary compound hydroxides, alkali metal carbonates when adjusting to basicity, and inorganic acids and organic acids when adjusting to acidity.

  Specifically, amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, quaternary Examples thereof include alkali metal carbonates such as phosphonium hydroxide, lithium carbonate, sodium carbonate, and potassium carbonate.

  Also, salts formed with inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and boric acid and monovalent weak cations such as ammonium sulfate and ammonium phosphate, acetic acid, succinic acid, lactic acid, salicylic acid, benzoic acid, glucuronic acid, ascorbine Acid, arginic acid, cysteine, oxalic acid, fumaric acid, maleic acid, malonic acid, lysine, malic acid, citric acid, glycine, glutamic acid, succinic acid, tartaric acid, phthalic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid Organic acids such as furan carboxylic acid, pyridine carboxylic acid, coumarinic acid, thiophene carboxylic acid, nicotinic acid, carborane acid, or derivatives of these compounds.

These pH adjusters are not limited to the above compounds. According to the characteristics of the ink depending on the pH change, the optimum pKa is used in a timely manner, and may be used singly or in combination of two or more or in combination with a buffer agent. It doesn't matter.
These are available from various manufacturers including Tokyo Chemical Industry Co., Ltd.

  Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate, dicyclohexyl ammonium nitrite, and benzotriazole.

<Penetration agent>
As a penetrating agent, it is possible to add it as necessary in order to supplement the penetrability by a surfactant or an organic solvent. Such a penetrant preferably contains at least one polyol having a solubility in water of 20 ° C. of 0.2% by mass or more and less than 5.0% by mass.
Among such polyols, aliphatic diols include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2-diethyl-1,3- Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1, Specific examples include 2-diol, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, and the like.
Of these, the most desirable are 2-ethyl-1,3-hexanediol and / or 2,2,4-trimethyl-1,3-pentanediol.

  Other penetrants that can be used in combination include polyethylene alcohols such as diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, and tetraethylene glycol chlorophenyl ether. Examples include alkyl and aryl ethers, lower alcohols such as ethanol, and the like, as long as they can be dissolved in a cleaning solution and adjusted to desired physical properties.

  The amount of penetrant added is preferably in the range of 0 to 4.0% by mass. When the amount added is more than 4.0% by mass, the dispersion stability of the pigment dispersion of the ink to be cleaned is impaired, the dispersion is aggregated, and the permeability to the ink flow path member is more than necessary. This causes liquid contact problems such as erosion of the member and swelling and elution of the adhesive.

◎ Ink The combination of cleaning liquid and ink is important. Color materials, resin fine particles, surfactants, water-soluble organic solvents, penetrants, antifoaming agents, and other additives are blended in inkjet inks. Regarding surfactants, water-soluble organic solvents, penetrants, and additives, Substances similar to the cleaning liquid can be used. The blending amount may be optimized in order to develop a function intended for printing.
Hereinafter, an additive different from the cleaning liquid as a component of the ink-jet ink will be described.

<Color material>
As for the color material, a pigment is mainly used from the viewpoint of weather resistance. However, for the purpose of adjusting the color tone, a dye may be contained at the same time as long as the weather resistance is not deteriorated.
Inorganic pigments include titanium oxide and iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chromium yellow, carbon produced by known methods such as contact method, furnace method, thermal method, etc. Black can be used.

  Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (eg, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines). Pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye type chelates, acidic dye type chelates), nitro pigments, nitroso pigments, aniline black, and the like can be used. Of these pigments, those having good affinity with water are particularly preferably used.

As specific examples of pigments that are more preferably used in the above pigments,
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), oxidation Examples thereof include metals such as titanium and organic pigments such as aniline black (CI Pigment Black 1).

Further, for color use, 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 , 408, 109, 110, 117, 120, 128, 138, 150, 151, 153, 183, 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 Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 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, C.I. I. . Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. . Pigment Bull-1, 2, 15, 15: 1, 15: 2, 15: 3 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. . Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.
Examples of other suitable colored pigments are The Color Index, 3rd edition (The SOC, et. Of Dyers and Colorists, 1982).
It is described in.

  Among these pigments, a preferable form is one whose surface is modified so that at least one hydrophilic group is bonded directly or via another atomic group to the surface of the pigment. For this purpose, a specific functional group (a functional group such as a sulfone group or a carboxyl group) is chemically bonded to the surface of the pigment, or wet oxidation is performed using hypohalous acid and / or a salt thereof. A method such as processing is used. Among these, a preferable form is a form in which carboxyl groups are bonded to the surface of the pigment and dispersed in water. In this case, since the pigment is surface-modified and the carboxyl group is bonded, not only the dispersion stability is improved, but also high-quality printing quality is obtained and the water resistance of the recording medium after printing is further improved. .

  In addition, since this form of ink has excellent redispersibility after drying, printing is paused for a long period of time, and even when ink moisture near the nozzles of the inkjet head evaporates, it does not cause clogging and is easily improved with a simple cleaning operation. Printing becomes possible. Further, this self-dispersing pigment has a particularly large synergistic effect when combined with a surfactant and a penetrating agent, which will be described later, and it is possible to obtain a more reliable and high-quality image.

  It is also possible to use a polymer emulsion in which a pigment is contained in fine polymer particles in addition to the pigment in the above form. The polymer emulsion containing a pigment is one in which a pigment is encapsulated in polymer fine particles and / or a pigment adsorbed on the surface of the polymer fine particles. In this case, it is not necessary that all the pigments are encapsulated and / or adsorbed, and the pigments may be dispersed in the emulsion as long as the effects of the present invention are not impaired. Examples of the polymer that forms the polymer emulsion include vinyl polymers, polyester polymers, polyurethane polymers, and the like. Particularly preferably used polymers are vinyl polymers and polyester polymers, Japanese Patent Application Laid-Open No. 2000-53897, The polymers disclosed in 2001-139849 are cited.

In the present invention, not only the pigment but also the following dyes can be used in combination.
For example, C.I. I. . Acid Yellow 17, 23, 42, 44, 79, 142
C. I. . Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254 289
C. I. . Acid Blue 9, 29, 45, 92, 249
C. I. . Acid Black 1, 2, 7, 24, 26, 94
C. I. . Food Yellow 2, 3, 4
C. I. . Food Red 7, 9, 14
C. I. . Food Black 1, 2

As a direct dye, C.I. I. . Direct yellow 1, 12, 24, 26, 33, 44, 50, 120, 132, 142, 144, 86
C. I. . Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227
C. I. . Direct Orange 26, 29, 62, 102
C. I. . Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202
C. I. . Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171

C. as a basic dye I. . Basic Yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 465, 67 70, 73, 77, 87, 91
C. I. . Basic Red 2, 12, 13, 14, 15, 18, 22, 23, 24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52, 54, 59, 68, 69, 70 73, 78, 82, 102, 104, 109, 112
C. I. . Basic Blue 1, 3, 5, 7, 9, 21, 22, 26, 35, 41, 45, 47, 54, 62, 65, 66, 67, 69, 75, 77, 78, 89, 92, 93 , 105, 117, 120, 122, 124, 129, 137, 141, 147, 155
C. I. . Basic Black 2, 8

As a reactive dye, C.I. I. . Reactive Black 3, 4, 7, 11, 12, 17
C. I. . Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67
C. I. . Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97
C. I. . Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95
Etc. can be used.

Of these, acid dyes and direct dyes are particularly preferable.
Other than these, although the structure is not disclosed, those commercially available as inkjet dyes can be used. Inkjet dyes can be obtained from FUJIFILM Imaging Colorant Co., Ltd., Nippon Kayaku Co., Ltd., Mitsubishi Chemical Co., Ltd., Daiwa Kasei Co., Ltd., Clariant Co., Ltd., Ciba Special D Chemicals Co., Ltd. and the like.
The addition amount of the coloring material in the ink is preferably about 1 to 15% by mass, more preferably about 3 to 12% by mass.

<Resin fine particles>
As the resin fine particles added to the ink, it is desirable to use a water-dispersible resin.
Examples of water-dispersible resins include condensation synthetic resins (polyester resins, polyurethane resins, polyepoxy resins, polyamide resins, polyether resins, silicon resins, etc.) and addition synthetic resins (polyolefin resins, polystyrene resins, polyvinyl alcohol resins). , Polyvinyl ester resins, polyacrylic acid resins, unsaturated carboxylic acid resins, etc.), natural polymers (celluloses, rosins, natural rubber, etc.) can be used, and the resins can be used as homopolymers. It may be used as a composite resin by being used as a copolymer, and any of single phase structure type, core shell type, and power feed type emulsions can be used.

  As the water-dispersible resin, a resin having a hydrophilic group in the resin itself and having a self-dispersibility, or a resin itself having no dispersibility and imparted with a surfactant or a resin having a hydrophilic group can be used. In particular, an emulsion of resin particles obtained by emulsification and suspension polymerization of an ionomer or an unsaturated monomer of a polyester resin or a polyurethane resin is optimal. In the case of emulsion polymerization of unsaturated monomers, a resin emulsion is obtained by reacting with water to which an unsaturated monomer, a polymerization initiator, a surfactant, a chain transfer agent, a chelating agent, a pH adjusting agent, and the like are added. Therefore, a water-dispersible resin can be easily obtained, and the desired properties can be easily produced because the resin configuration can be easily changed. Usable unsaturated monomers include unsaturated carboxylic acids, (meth) acrylic acid ester monomers, (meth) acrylic acid amide monomers, aromatic vinyl monomers, vinyl cyanide compounds Isomers, vinyl monomers, allyl compound monomers, olefin monomers, diene monomers, oligomers having unsaturated carbon, and the like can be used alone or in combination. By combining these monomers, the properties can be flexibly modified, and the properties of the resin can be modified by performing a polymerization reaction or a graft reaction using an oligomer type polymerization initiator.

Specific examples of the unsaturated monomer are shown below.
(Unsaturated carboxylic acids)
Acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, etc.

((Meth) acrylic acid esters)
(Monofunctional)
Methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, Phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, methacryloxyethyltrimethylammonium salt, 3-methacryloxypropyltrimethoxysilane methyl acrylate, ethyl Acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate , Phenyl acrylate, benzyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dimethylaminoethyl acrylate, acryloxyethyltrimethylammonium salt, etc.

(Polyfunctional)
Ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol Dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polybutylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, polyethylene Glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, polypropylene glycol diacrylate, 2,2 '-Bis (4-acryloxypropyloxyphenyl) propane, 2,2'-bis (4-acryloxydiethoxyphenyl) propane trimethylolpropane triacrylate, trimethylolethane triacrylate, tetramethylolmethane triacrylate, ditrimethylol Tetraacrylate, tetramethylolmethane tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate

((Meth) acrylic acid amide monomers)
Acrylamide, methacrylamide, N, N-dimethylacrylamide, methylenebisacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, etc.

(Aromatic vinyl monomers)
Styrene, α-methylstyrene, vinyltoluene, 4-t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene, divinylbenzene, etc. (vinyl cyanide monomer)
Acrylonitrile, methacrylonitrile, etc.

(Allyl compound monomers)
Allylsulfonic acid salt, allylamine, allyl chloride, diallylamine, diallyldimethylammonium salt, etc. (olefin monomers)
Ethylene, propylene, etc.

(Diene monomers)
Butadiene, chloroprene, etc. (vinyl monomers)
Vinyl acetate, vinylidene chloride, vinyl chloride, vinyl ether, vinyl ketone, vinyl pyrrolidone, vinyl sulfonic acid and its salts, vinyl trimethoxysilane, vinyl triethoxysilane, etc.

(Oligomers with unsaturated carbon)
Styrene oligomers with methacryloyl groups, styrene-acrylonitrile oligomers with methacryloyl groups, methyl methacrylate oligomers with methacryloyl groups, dimethylsiloxane oligomers with methacryloyl groups, polyester oligomers with acryloyl groups, etc.

  By using these monomers alone or in combination, it is possible to flexibly modify the properties of the water-dispersible resin. Further, such a water-dispersible resin has a strong alkalinity and a strong acidity, and thus the molecular chain is broken such as dispersion breakage and hydrolysis. Therefore, the pH is preferably 4 to 12. In particular, the pH is preferably 6 to 11 and more preferably 7 to 9 in terms of miscibility with the water-dispersed coloring material.

  The particle size of the water-dispersible resin is related to the viscosity of the dispersion. When the composition is the same, the viscosity at the same solid content increases as the particle size decreases. The average particle size of the water-dispersible resin is desirably 50 nm or more so that the viscosity does not become excessively high when the ink is formed. If the particle size is several tens of μm, it becomes larger than the nozzle opening of the ink jet head and cannot be used. It is known that if particles having a large particle diameter exist in the ink even if they are smaller than the nozzle opening, the ejection property is deteriorated. The average particle size is desirably 500 nm or less, and more preferably 150 nm or less, in order not to inhibit the ink ejection properties.

  The water-dispersible resin has a function of fixing the water-dispersed color material on the paper surface, and it is desired to form a film at room temperature to improve the fixability of the color material. For this purpose, the minimum film-forming temperature (MFT) is preferably not higher than room temperature, and preferably not higher than 20 ° C. However, when the glass transition point is −40 ° C. or lower, the resin film becomes more viscous and the printed matter is tacky. Therefore, a water dispersible resin having a glass transition point of −30 ° C. or higher is desirable.

<Surfactant>
As the surfactant, an anionic surfactant, a nonionic surfactant, or an amphoteric surfactant is used. A surfactant that does not impair the dispersion stability is selected depending on the combination of the color material, the wetting agent, and the water-soluble organic solvent.

  Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecyl benzene sulfonate, oxalate sulfonate, laurate, polyoxyethylene alkyl ether sulfate salt, and the like.

  Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene polyoxypropylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene Examples thereof include ethylene alkyl phenyl ether, polyoxyethylene alkyl amine, and polyoxyethylene alkyl amide.

  Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine. Specific examples below are preferably used, but are not limited thereto. Examples include lauryl dimethylamine oxide, myristyl dimethylamine oxide, stearyl dimethylamine oxide, dihydroxyethyl lauryl amine oxide, polyoxyethylene coconut oil alkyl dimethyl amine oxide, dimethyl alkyl (coconut) betaine, and dimethyl lauryl betaine.

  Such surfactants are Nikko Chemicals Co., Ltd., Nippon Emulsion Co., Ltd., Nippon Shokubai Co., Ltd., Toho Chemical Co., Ltd., Kao Co., Ltd., Adeka Co., Ltd., Lion Co., Ltd., Aoki Yushi Co., Ltd. ), And a surfactant manufacturer such as Sanyo Kasei Co., Ltd.

  Acetylene glycol surfactants include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5- An acetylene glycol type such as dimethyl-1-hexyn-3-ol (for example, Surfynol 104, 82, 465, 485 or TG from Air Products (USA)) can be used. TG indicates good print quality.

  Fluorosurfactants include perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate ester, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl betaine, perfluoroalkylamine oxide compounds, Examples thereof include polyoxyalkylene ether polymers having a fluoroalkyl ether group in the side chain, sulfate salts thereof, and fluorine-based aliphatic polymer esters.

  Examples of commercially available fluorosurfactants include Surflon S-111, S-112, S-113, S121, S131, S132, S-141, and S-145 (Asahi Glass Co., Ltd.), Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431, FC-4430 (manufactured by Sumitomo 3M), FT-110, 250, 251 , 400S (manufactured by Neos), Zonyl FS-62, FSA, FSE, FSJ, FSP, TBS, UR, FSO, FSO-100, FSN N, FSN-100, FS-300, FSK (manufactured by Dupont), poly There are Fox PF-136A, PF-156A, PF-151N (manufactured by OMNOVA), etc., which are easily available from the manufacturer.

  The surfactant is not limited to these, and may be used alone or in combination. Even if it is not easily dissolved by itself in the recording liquid, it can be solubilized by mixing and exist stably.

In order to exert a penetrating effect as the total amount of the surfactant, it is desirable to contain 0.01 to 5.0% by mass with respect to the total amount of the ink. If the total amount of the surfactant is less than 0.01% by mass, the effect of imparting wettability is low and insufficient to improve the filling property. The water repellent part of the head is wetted and the discharge function of the head is lowered. Further, in the visibility of the printed matter after the discharge inspection, the permeability to the recording medium is unnecessarily high, the image density is lowered, and the visibility is lowered. Furthermore, in some surfactants, the solubility of the surfactant is insufficient when it is dried, and the viscosity increases due to the influence of the surfactant. Therefore, addition of more than 5.0% by mass causes various problems.
The addition of such a surfactant is more preferably 0.5 to 2.0% by mass.

<Antifoaming agent>
As the antifoaming agent, a generally used antifoaming agent can also be used. These include silicone antifoaming agents, polyether antifoaming agents, fatty acid ester antifoaming agents, etc., and these may be used alone or in combination of two or more. Among these, combined use with a silicone antifoaming agent is preferable at the point which is excellent in the bubble-breaking effect.

  Examples of the silicone antifoaming agent include an oil type silicone antifoaming agent, a compound type silicone antifoaming agent, a self-emulsifying type silicone antifoaming agent, an emulsion type silicone antifoaming agent, and a modified silicone antifoaming agent. Examples of the modified silicone antifoaming agent include amino-modified silicone antifoaming agents, carbinol-modified silicone antifoaming agents, methacrylic-modified silicone antifoaming agents, polyether-modified silicone antifoaming agents, alkyl-modified silicone antifoaming agents, and higher fatty acids. Examples thereof include an ester-modified silicone antifoaming agent and an alkylene oxide-modified silicone antifoaming agent. Among these, the self-emulsifying type silicone antifoaming agent and the emulsion type silicone antifoaming agent are preferable in consideration of use in the recording ink which is an aqueous medium.

  Commercially available products may be used as the general antifoaming agent. Examples of the commercially available products include silicone antifoaming agents (KS508, KS531, KM72, KM85, etc.) manufactured by Shin-Etsu Chemical Co., Ltd. Silicone antifoaming agent (Q2-3183A, SH5510, etc.) manufactured by Dow Corning Co., Ltd. Silicone antifoaming agent (SAG30, etc.) manufactured by Nihon Unicar Co., Ltd., Antifoaming agent (Adeka) manufactured by Asahi Denka Kogyo Co., Ltd. Nate series).

Although there is no restriction | limiting in particular as content in the ink of an antifoamer, Since there are many things which an antifoamer does not melt | dissolve completely in an ink and there is a high possibility of separating and depositing, it is better not to add as much as possible. However, if foaming occurs at the time of filling, filling properties deteriorate, so it is desirable to use the minimum amount. For example, 0 to 3.0% by mass is preferable, and 0 to 0.5% by mass is more preferable.
Some of them contain inorganic fine particles from the viewpoint of using a common antifoaming agent and enhancing the bubble breaking effect, but it is preferable not to use them as an antifoaming agent used in ink.

About the ink jet device As the ink jet recording device of the present invention, the piezoelectric film is used as a pressure generating means for pressurizing the ink in the ink flow path, and the diaphragm that forms the wall surface of the ink flow path is deformed to increase the volume in the ink flow path. A so-called piezo type that discharges ink droplets by changing (refer to Japanese Patent Laid-Open No. 2-51734), or a so-called thermal type that generates bubbles by heating ink in an ink flow path using a heating resistor. (Refer to Japanese Patent Application Laid-Open No. 61-59911), a diaphragm that forms the wall surface of an ink flow path and an electrode are arranged opposite to each other, and the diaphragm is deformed by an electrostatic force generated between the diaphragm and the electrode. Thus, any ink jet recording apparatus such as an electrostatic type that discharges ink droplets by changing the volume of the ink flow path (see Japanese Patent Application Laid-Open No. 6-71882). Can be used in a good manner.
The cleaning liquid of the present invention can be suitably used in various fields. In particular, it can be suitably used in an image forming apparatus (printer or the like) using an ink jet recording method, and can be shipped by filling an ink flow path other than the head.

Cleaning Method The present invention proposes a cleaning method for an ink jet recording apparatus using the cleaning liquid, but the specific cleaning method is not particularly limited except that the cleaning liquid is used. Since the process of supplying and discharging the cleaning liquid into the ink flow path may be repeated, for example, the supply and discharge of the cleaning liquid from the cartridge containing the cleaning liquid to the ink flow path using the supply and suction mechanisms of the ink jet recording apparatus main body. Examples include a method of repeating, a method of supplying a cleaning liquid by pressurizing a cleaning liquid container from the outside, a method of sucking from the head side using an external pump, and the like. Further, it is preferable to repeat the step of supplying and discharging the cleaning liquid into the ink flow path by these methods until the concentration of the colored fine particles in the discharged liquid becomes 5% by mass or less. Thereby, the ink flow path of the ink jet recording apparatus can be sufficiently cleaned.

Examples are shown below, but are not limited thereto.
<Adjustment of cleaning liquid>
The cleaning liquid was adjusted according to the following procedure. First, a pH adjuster, a surfactant, and water are mixed and dissolved uniformly. A water-soluble organic solvent was mixed there and stirred for 1 hour to mix uniformly. This mixed solution was filtered under pressure through a 0.8 μ cellulose acetate membrane filter to remove coarse particles and dust to obtain a cleaning solution used for evaluation.
The cleaning liquid was prepared according to the following table using the above adjustment method.
In addition, the unit of the numerical value which shows the component ratio in a table | surface is the mass%.

<Adjustment of pigment ink>
-Preparation of polymer solution-
After sufficiently replacing nitrogen gas in the 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, Polyethylene glycol methacrylate 4.0 g, styrene macromer 4.0 g, mercaptoethanol 0.4 g, and methyl ethyl ketone 40 g were mixed and heated to 65 ° C.

  Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxylethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, azobismethylvaleronitrile A mixed solution of 2.4 g and methyl ethyl ketone 342 g was dropped into the flask over 2.5 hours.

After dropping, a mixed solution of 0.8 g of azobismethylvaleronitrile 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 azobismethylvaleronitrile was added and further aging was performed for 1 hour.
After completion of the reaction, 800 g of a polymer solution having a concentration of 50% by mass was obtained.

-Preparation of aqueous dispersion of yellow pigment-containing polymer fine particles-
28 g of the polymer solution and C.I. I. 26 g of Pigment Yellow 74, 13.6 g of a 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone and 13.6 g of ion-exchanged water were sufficiently stirred, and then kneaded using a roll mill.
The obtained paste was put into 200 g of pure water and stirred sufficiently, and then methyl ethyl ketone and water were distilled off using an evaporator, and an aqueous dispersion of yellow pigment-containing polymer fine particles having a pigment content of 15% by mass and a solid content of 20% by mass. Got.

-Preparation of yellow pigment ink-
The yellow pigment ink was adjusted according to the following procedure. First, 15% by mass of 1,3-butanediol, 15% by mass of glycerin, 1% by mass of Polyfox PF-151N manufactured by OMNOVA, and 2% by mass of octanediol are mixed and stirred uniformly for 1 hour. 40% by weight of the yellow pigment-containing polymer fine particle aqueous dispersion was added to this mixed solution, and the remaining amount of water was added so that the total amount was 100% by mass, followed by stirring for 1 hour. Thereafter, the mixture was filtered under pressure through a 0.8 μ cellulose acetate membrane filter to remove coarse particles, and an evaluation ink was obtained.

-Preparation of aqueous dispersion of magenta pigment-containing polymer fine particles-
17.5 g of the polymer solution and C.I. I. 32.5 g of Pigment Red 122, 8.5 g of 1 mol / L potassium hydroxide aqueous solution, 13 g of methyl ethyl ketone and 13.6 g of ion-exchanged water were sufficiently stirred, and then kneaded using a roll mill.
The obtained paste was put into 200 g of pure water and stirred sufficiently, and then methyl ethyl ketone and water were distilled off using an evaporator, and an aqueous dispersion of magenta pigment-containing polymer fine particles containing 15% by mass of pigment and 20% by mass of solids. Got.

-Preparation of magenta pigment ink-
The magenta pigment ink was adjusted in the following procedure. First, 15% by mass of 3-methyl-1,3-butanediol, 15% by mass of glycerin, 0.5% by mass of Zonyl FSO-100 manufactured by Dupont, and 1% by mass of 1,2-hexanediol were mixed and stirred uniformly for 1 hour. To mix. 40% by mass of the magenta pigment-containing polymer fine particle aqueous dispersion was added to the mixed solution, and the remaining amount of water was added so that the total amount was 100% by mass, followed by stirring for 1 hour. Thereafter, the mixture was filtered under pressure through a 0.8 μ cellulose acetate membrane filter to remove coarse particles, and an evaluation ink was obtained.

<Uniformity as a liquid>
The uniformity of the cleaning liquid was evaluated by allowing the cleaning liquid obtained according to the adjustment of the cleaning liquid to stand for 1 hour, and visually observing the state of the liquid after standing.
○: No separation or insoluble matter, uniform state ×: Some of the components are separated or insoluble matter is present, non-uniform state

<Measurement of viscosity of cleaning liquid>
To measure the viscosity of the cleaning liquid, a viscosity meter RE80L manufactured by Toki Sangyo Co., Ltd. was used, and the liquid viscosity at 25 ° C. was measured at 100 revolutions or 50 revolutions.

<Evaluation of mixing properties of cleaning liquid and ink>
A mixed liquid containing 97% by mass of the cleaning liquid and 3% by mass of the ink was prepared, and was allowed to stand at 65 ° C. for 50 hours to evaluate the appearance change.
○: The presence or absence of separation is not known Δ: Light and shade are observed ×: Separation is occurring In addition, those that cannot ensure the uniformity as a cleaning liquid are not uniform when mixed with ink, and thus are excluded from the evaluation.

<Evaluation of cleaning performance of cleaning liquid>
-Initial state setting Ink cartridge for ink jet printer (IPSIO GX3000, manufactured by Ricoh Co., Ltd.), ink in the ink supply path and head, and then filled with magenta ink of adjustment example instead of black and cyan ink, magenta The cartridge filled with the yellow ink of the adjustment example was attached instead of the yellow ink, and after the filling operation, the head refreshing operation was repeated 10 times, and the ink in the ink supply path and the head was replaced with the ink of the adjustment example. Thereafter, a nozzle check pattern was printed, and a head refreshing operation was performed until there was no missing nozzle.

-Cleaning process After confirming that the nozzles of the inkjet printer are not missing, attach a cartridge filled with the cleaning solution instead of all the cartridges, and perform head refreshing operation 6 times. Thereafter, the maintenance unit of the printer is operated, and the operation of sucking 4.5 cc from each head and refilling it is repeated three times. After refilling, 2 cc was sucked from each head, and then the nozzle surface was wiped to clean the path in the ink jet apparatus.

・ Evaluation of cleaning properties The last suction cleaning solution is collected, and the absorbance is measured at 563 nm with magenta ink and 421 nm with yellow ink, and compared with the absorbance at the same wavelength of the ink, the concentration of colored fine particles in the collected cleaning solution ( Mass%) was calculated.
The cleaning liquid that causes separation in the evaluation of the mixing properties of the cleaning liquid and the ink causes separation of the color material component in the ink at the stage of mixing with the ink in the cleaning performance evaluation apparatus (inkjet printer), and the particle size Large precipitates are generated. For this reason, nozzle clogging and filter clogging occurred in the evaluation device, so they were excluded from the evaluation.

<Evaluation of initial fillability>
Using an ink jet printer (IPSIO GX3000, manufactured by Ricoh Co., Ltd.), wash the ink jet printer by the cleaning treatment described in the cleaning property of the cleaning liquid, and place the nozzle surface with a moisturizing cap in a 50 ° C., 60% RH environment. After being left for one month, the ink cartridge filled with the yellow ink and magenta ink shown in the adjustment example was attached, and the initial filling operation was performed. After that, the nozzle check pattern is printed, the head refreshing operation is repeated after the filling operation, and the number of head refreshing until the ejection failure (nozzle ejection or ejection bending = white or black streaks are conspicuous in the image) is eliminated. Was evaluated. (Up to 8 times)
○: Head refreshing 2 times or less △: Head refreshing 3 times or more and 4 times or less X: Head refreshing 5 times or more required or unrecoverable In addition, as in the cleaning performance evaluation of cleaning liquid, separation is performed by evaluating the mixing characteristics of cleaning liquid and ink. Cleaning liquids that cause stagnation were excluded from the evaluation due to nozzle clogging and filter clogging.
The evaluation results are shown in the following table.

  From the above results, by using a cleaning liquid as shown in the examples, it is possible to provide a cleaning liquid that has high mixing stability with ink, good cleaning properties, and excellent initial filling properties.

JP 2007-119658 A JP 2007-169314 A JP 2007-091846 A JP 2005-146224 A JP 2009-012361 A

Claims (6)

Cleaning liquid for an ink jet recording apparatus for cleaning a flow path of an ink jet recording apparatus using an ink containing at least colored resin fine particles containing a water-insoluble or hardly soluble coloring material in resin fine particles, a water-soluble organic solvent, and water. And
The cleaning liquid contains at least water, a water-soluble organic solvent, and a polyoxyalkylene monoalkyl ether represented by the following general formula (1),
The viscosity of the cleaning liquid at 25 ° C. is 2.5 mPa · s or more,
A cleaning liquid for an ink jet recording apparatus, comprising at least glycerin as a water-soluble organic solvent in the cleaning liquid, wherein a content of the glycerin is 4% by mass or more and 20% by mass or less with respect to the cleaning liquid.
2. The flow path of an ink jet recording apparatus using an ink containing colored fine particles containing at least CI Pigment Red 122 or CI Pigment Yellow 74 as a coloring material is washed. The washing | cleaning liquid for inkjet recording apparatuses of description.   The cleaning liquid for an ink jet recording apparatus according to claim 1, wherein the cleaning liquid has a viscosity at 25 ° C. of 15 mPa · s or less.   The cleaning liquid for an ink jet recording apparatus according to any one of claims 1 to 3, wherein the water-soluble organic solvent contains 1,3-butanediol and / or 3-methyl-1,3-butanediol. .   A cleaning method for an inkjet recording apparatus, wherein the cleaning liquid for an inkjet recording apparatus according to any one of claims 1 to 4 is passed through an inkjet recording apparatus having an ink supply path filled with ink to replace the liquid. .   6. The ink jet recording according to claim 5, wherein the step of supplying and discharging the cleaning liquid into the ink flow path of the ink jet recording apparatus is repeated until the concentration of the colored fine particles in the discharged liquid becomes 5% by mass or less. How to clean the device.