JP2014095057A - Cleaning fluid for inkjet device and cleaning method of device for inkjet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning fluid for an inkjet device suppressing adverse effects on discharge stability of heads.SOLUTION: The cleaning fluid for an inkjet device contains polyol having a dissolution amount to water at a standard condition (25°C and 1 atmosphere of pressure) of 10 wt.% or less.

Description

  The present invention relates to a cleaning liquid for an inkjet apparatus and a cleaning method for an inkjet apparatus.

  In general, a wide format printer includes a recording head composed of a liquid ejection head that ejects ink droplets, and forms an image by adhering ink droplets to a sheet while conveying a medium. 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 large number of pores called 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.

  The 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 supplying liquid to the pressure generating portion, a filter portion for filtering the liquid flowing into the liquid chamber, and the like. Constructed, processed and formed with very high accuracy.

  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, a 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 ink jet apparatus must be washed away.

  Conventionally, water alone, a surfactant aqueous solution, and the like have been used, but these have problems such as detergency in refilling and occurrence of ejection defects, while ensuring cleanability.

  More recently, inks using pigments as colorants have been put into practical use from the viewpoints 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-mentioned problems are becoming 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 describe that a resin solvent is added 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 Patent Documents 1 and 2 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. Therefore, Patent Document 5 describes a filling liquid to which a corrosion inhibitor that prevents elution of a metal member and enables washing and storage is added. However, the compatibility with cleanability is 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.

  In Patent Document 6, polyoxyalkylene monoalkyl ether is used for the cleaning liquid, but there are drawbacks that the solubility in water is limited, the cleaning effect is low, and the head cleaning effect is poor. In Patent Document 7, glycol ethers or glycol esters are specified, but they are contained in any conventional cleaning agent, and the cleaning effect is limited. In Patent Document 8, glycol ethers or glycol esters are defined, and further, the amount of dissolved oxygen is defined, but the cleaning effect is limited as described above. Patent Document 9 defines an ethynediol nonionic surfactant, a polyhydric alcohol, and an antiseptic, but has a poor cleaning effect such as dissolving foreign substances formed on the head.

JP 2007-119658 A JP 2007-169314 A JP 2007-091846 A JP 2005-146224 A JP 2009-012361 A JP 2011-140556 A JP 2008-274016 A JP 2010-99874 A JP 2007-91846 A

  Latex inks have been developed in recent years, but latex inks also tend to have poor dispersion stability in the liquid after washing, like pigments coated with poorly water-soluble resins. In addition, white pigment inks often use heavy pigments such as titanium oxide regardless of oiliness or aqueousness, and the pigments in the ink settle and deposit in the ink flow path or head, causing abnormal discharge. There are many cases. Therefore, it is more strongly required to stabilize the ejection of the head.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a cleaning liquid for an inkjet apparatus that suppresses adverse effects on the ejection stability of the head. For example, for latex inks, particularly latex containing titanium oxide, the ink flow path can be sufficiently cleaned, maintenance around the head can be performed, and the ink ejection stability after cleaning is not adversely affected. Provide a cleaning solution.

  In this specification, “latex ink” refers to an ink in which a binder resin is milky or suspended. The binder resin is not limited to latex such as rubber, and may be an aqueous resin or the like.

  The ink-jet apparatus cleaning liquid according to the present invention is characterized in that it contains a polyol having a solubility in water of 10 wt% or less in a standard state (25 ° C., 1 atm).

  If such a polyol is included, the amount of dissolved oxygen in the liquid can be reduced. If the dissolved oxygen amount is low, bubbles are not easily generated in the cleaning liquid. That is, even if the cleaning liquid remains in the head and mixes with the ink, bubbles are hardly generated in the ink. If bubbles are generated, the pigments and binder resin in the ink are aggregated to lead to ejection failure. However, according to the present invention, since bubbles are not easily generated, aggregation is unlikely to occur and the ejection stability is excellent. Therefore, an adverse effect on the ejection stability of the head is suppressed.

  In the inkjet apparatus cleaning liquid according to the present invention, the dissolved oxygen amount is more preferably 5 mg / l or less.

  By reducing the amount of dissolved oxygen in this way, the generation of bubbles can be further suppressed. Therefore, the adverse effect on the discharge stability can be further suppressed.

  The inkjet apparatus cleaning liquid according to the present invention may further include water, a water-soluble organic solvent, and glycol ethers. It can be suitably used as a cleaning liquid.

  In the inkjet apparatus cleaning liquid according to the present invention, the polyol is more preferably 2-ethyl-1,3-hexanediol or 2,2,4-trimethyl-1,3-pentanediol.

  The amount of dissolved oxygen in the cleaning liquid can be further reduced. Therefore, the adverse effect on the discharge stability can be further suppressed.

  In the inkjet apparatus cleaning liquid according to the present invention, the content of the polyol is more preferably 0.1 wt% or more and 7.0 wt% or less.

  By being 0.1 weight% or more, the effect of reducing the dissolved oxygen concentration by a polyol can fully be acquired. Moreover, although a polyol is hard to melt | dissolve in water, it becomes easy to manufacture the washing | cleaning liquid for inkjet devices which concerns on this invention by setting it as 7 weight% or less.

  In the inkjet apparatus cleaning liquid according to the present invention, it is more preferable that an antioxidant is contained, and the antioxidant is butylhydroxytoluene.

  The oxidation of the head surface can be prevented more efficiently.

  The cleaning liquid for an inkjet device according to the present invention includes a water-soluble organic solvent, and the water-soluble organic solvent is glycerin, trimethylolpropane, 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, 1,6-hexanediol, 2-methyl- More preferably, it is at least one selected from the group consisting of 2,4-hexanediol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, tetramethylurea and urea.

  Since these water-soluble organic solvents are often used as ink solvents in order to disperse the pigment, even if the cleaning liquid is mixed with the ink, it can prevent adverse effects on the ink.

  The inkjet apparatus cleaning liquid according to the present invention includes glycol ethers, and the glycol ethers are selected from the group consisting of diethylene glycol diethyl ether, diethylene glycol isobutyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, and triethylene glycol monobutyl ether. More preferably, it is at least one selected.

  These glycol ethers are often used as ink additives in order to improve the wettability of the ink with respect to the recording medium. Therefore, even if the cleaning liquid is mixed with the ink, it has an adverse effect on the ink. Can be prevented.

In the cleaning liquid for an inkjet device according to the present invention, the following general formula (1)
R—O— (CH ₂ CH ₂ O) _x — (CH ₂ CH (CH ₂ ) CH ₂ O) _y —H (1)
(In the formula (1) R: a branched _{- (CH 2) m -CH 3} , m = 3~15 integer, x = 6 to 15 integer, an integer of y = 1 to 5)
It is more preferable that the polyoxyalkylene monoalkyl ether shown in FIG.

  By including this surfactant, the cleaning effect can be further improved.

  In the inkjet apparatus cleaning liquid according to the present invention, the viscosity at 25 ° C. is 2.0 mPa · s or more and more preferably 10 mPa · s or less.

  Inks often have the above viscosity. By setting the cleaning liquid to such a viscosity, even if the cleaning liquid is mixed with the ink, the viscosity of the ink can be prevented from being lost.

  The cleaning method for an ink jet apparatus according to the present invention is characterized in that the cleaning liquid for an ink jet apparatus according to the present invention is passed through an ink jet apparatus in which an ink supply path is filled with ink.

  Since the inkjet apparatus cleaning liquid according to the present invention is used, it is possible to clean the head and the like while suppressing adverse effects on the ink ejection stability.

  In the ink jet device cleaning method according to the present invention, the ink may include water, a water-soluble organic solvent, and a binder resin, and the binder resin may be emulsion or suspension.

  Latex inks tend to cause clogging of ejection, and further ejection stability is required. By using the cleaning liquid for an inkjet device according to the present invention, it is possible to further suppress adverse effects on ejection stability. it can.

  In the cleaning method for an ink jet apparatus according to the present invention, the minimum film forming temperature (MFT) of the binder resin may be 0 ° C. or less.

  The ink-jet apparatus cleaning liquid according to the present invention can also be suitably used for inks that easily form a film.

  In the ink jet device cleaning method according to the present invention, the ink may further include titanium oxide having an average particle diameter of 10 to 80 nm.

  The ink-jet apparatus cleaning liquid according to the present invention can also be suitably used for inks that easily form a film.

  According to the present invention, it is possible to suppress an adverse effect on the ejection stability of the head. For example, cleaning of the ink flow path and maintenance around the head can be sufficiently performed, and no problem occurs in ink refillability after cleaning. That is, even when the ink is refilled after cleaning, the ejection stability is not adversely affected.

  The ink-jet apparatus cleaning liquid according to the present invention contains a polyol having a solubility in water of 10 wt% or less in a standard state (25 ° C., 1 atm).

  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 cleaning liquid and time are required to completely replace the inside of the head with the cleaning liquid after cleaning, the efficiency is poor. Therefore, it is necessary to maintain the quality of the ink jet apparatus even when the ink is mixed to a certain density. If the compatibility between the cleaning liquid and the ink is poor, the ink aggregates and is attracted to the nozzles and filters of the inkjet head, causing ejection failure and increased resistance. Therefore, the ink properties are required to be stable even when the ink and the cleaning liquid are mixed.

  Further, by satisfying the cleaning property and the mixing property (good compatibility) with the ink, it is possible to ensure the refilling property when newly filling the ink. That is, even if ink is filled again, the ejection stability is not adversely affected.

<Polyol>
The polyol contained in the cleaning liquid for an ink jet device according to the present invention may be one having a solubility in water of 10 wt% or less in a standard state (25 ° C., 1 atm). That is, the amount of the polyol that can be dissolved in water in a standard state is 10 wt% or less.

  If such a polyol is included, the amount of dissolved oxygen in the liquid can be reduced. That is, once the amount of dissolved oxygen is adjusted to a low level by a method described later, oxygen is prevented from newly dissolving, so that the amount of dissolved oxygen can be kept low.

  If the dissolved oxygen amount is low, bubbles are not easily generated in the cleaning liquid. That is, even if the cleaning liquid remains in the head and mixes with the ink, bubbles are hardly generated in the ink. If bubbles are generated, the pigments and binder resin in the ink are aggregated to lead to ejection failure. However, according to the present invention, since bubbles are not easily generated, aggregation is unlikely to occur and the ejection stability is excellent. Therefore, an adverse effect on the ejection stability of the head is suppressed.

  The present inventors have obtained excellent head ejection stability by reducing the amount of dissolved oxygen by incorporating a polyol having a low solubility in water in a standard state (25 ° C., 1 atm) into the cleaning liquid. I found out that Oxygen is more polar and more soluble in water than nitrogen. Since the polyol contained in the inkjet apparatus cleaning liquid according to the present invention has low solubility in water, the proportion of oxygen taken into water is reduced, contributing to stabilization of the dissolved oxygen amount, and increasing the dissolved oxygen amount after storage. Is expected to decrease. Moreover, by increasing the amount of dissolved nitrogen, the dissolved oxygen is replaced with dissolved nitrogen, and the amount of dissolved oxygen is reduced.

  In addition, a polyol having low solubility in water in a standard state (25 ° C., 1 atm) can keep the amount of dissolved oxygen in the cleaning liquid low, and can prevent oxidation of the head surface. The reason is that the polyol has a low solubility in water and exhibits a property of an oily component at a blending amount exceeding 10%. The polyol has a low activity with respect to oxygen, and the dissolved oxygen amount of the polyol is much lower than that of water. Therefore, when the polyol contains the cleaning liquid, the dissolved oxygen amount is, for example, a low oxygen content of 5 mg / l or less. Can keep the state. If a cleaning solution having a low dissolved oxygen concentration is used, oxidation of the head surface can be prevented. From the viewpoint of antioxidant, an antioxidant described later may be added.

  Among the polyols having a solubility in water of 10 wt% or less in a standard state (25 ° C., 1 atm), those having 7 to 11 carbon atoms are more preferable. Specific examples of such a polyol include 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, and the like. The amount of dissolved oxygen in the cleaning liquid can be further reduced. Therefore, the adverse effect on the discharge stability can be further suppressed.

  Although content of a polyol is not specifically limited, For example, it is more preferable that they are 0.1 weight% or more and 7.0 weight% or less.

  By being 0.1 weight% or more, the effect of reducing the dissolved oxygen concentration by a polyol can fully be acquired. In addition, although the polyol is difficult to dissolve in water, the polyol used in the present invention can be easily dissolved if it is 7% by weight or less, so that the inkjet apparatus cleaning liquid according to the present invention can be easily manufactured.

<Amount of dissolved oxygen>
The amount of dissolved oxygen in the cleaning liquid for an ink jet apparatus according to the present invention is low in that it contains the above-mentioned polyol, but specifically, the lower the better, the lower the amount of dissolved oxygen is 5 mg / l or less. It is more preferable. By reducing the amount of dissolved oxygen in this way, it is possible to further suppress the generation of bubbles in the ink when mixed with the ink.

  The method for adjusting the amount of dissolved oxygen is not particularly limited, and there are a method of degassing ink under reduced pressure, a method of degassing by irradiating ultrasonic waves, a method of degassing with a hollow fiber membrane, and the like. In the examples described later, two methods of degassing under reduced pressure and a hollow fiber membrane were used. By these methods, the amount of dissolved oxygen can be suitably adjusted to, for example, 0.1 mg / l or a lower concentration.

  Examples of the method for measuring the dissolved oxygen concentration include the Ostwald method (see Experimental Chemistry Course 1, Basic Operation [1], page 241, 1: 2075, Maruzen), the method of measuring by the mass spectrum method, the oxygen concentration meter, It can be measured using colorimetric analysis. Moreover, it can measure simply even if it uses a commercially available dissolved oxygen concentration meter.

<Water>
The cleaning liquid for an inkjet apparatus according to the present invention may contain water. The cleaning liquid can be easily prepared, and even if it remains, it does not adversely affect the properties of the ink.

<Water-soluble organic solvent>
The cleaning liquid for an inkjet apparatus according to the present invention may contain a water-soluble organic solvent.

  As the water-soluble organic solvent, a solvent that is easy to hydrogen bond, has a high viscosity by itself, has a high equilibrium water content, and lowers the viscosity in the presence of water is more preferable.

  Such polyhydric alcohols include glycerin, trimethylolpropane, 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-butanetriol, 1,2,6-hexanetriol 2-methyl-2, 4-hexanediol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, tetramethylurea , Urea etc. That. These may be used alone or in combination. 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 for an inkjet apparatus according to the present invention can exhibit the effects of the present invention more preferably within a range of, for example, 20 to 60% by mass, and particularly preferably 30 to 50% by mass. Range. By setting the amount of the water-soluble organic solvent to 20% by mass or more, the moisture retention of the cleaning liquid is maintained and drying during storage is suppressed. Further, when the amount of the water-soluble organic solvent is 60% by mass or less, the viscosity of the cleaning liquid can be suppressed low, the filling property to the head can be improved, and the combustibility can be suppressed.

  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.

  Thus, it is more preferable to use a water-soluble organic solvent having moisture retention. A cleaning liquid containing a water-soluble organic solvent having moisture retention is more suitable for a pigment ink using a pigment that easily aggregates. For example, when a latex ink containing titanium oxide is used, the pigment and binder resin are not sufficiently bonded, resulting in an unstable pigment dispersion. However, a cleaning liquid containing a water-soluble organic solvent having moisture retention has high dispersion stability even when cleaning an ink jet device filled with latex ink containing titanium oxide, so that even a left ink has high reliability. Can keep sex.

<Glycol ethers>
The inkjet apparatus cleaning liquid according to the present invention may include glycol ethers. By including the glycol ethers, it becomes possible to have both the penetrating power in which the cleaning liquid mixes with the ink in the flow path in the inkjet head and the dispersing power to maintain the dispersed state of the pigment in the ink after mixing with the ink. . Furthermore, since the foaming property and defoaming property are appropriately suppressed, the generation of bubbles in the ink jet apparatus can be suppressed, and the cleaning property and the storage property can be exhibited.

  Examples of the glycol ethers contained in the inkjet apparatus cleaning liquid according to the present invention include diethylene glycol diethyl ether, diethylene glycol isobutyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, and triethylene glycol monobutyl ether. These may be used alone or in combination of two or more. These glycol ethers are often used as ink additives in order to improve the wettability of the ink with respect to the recording medium. Therefore, even if the cleaning liquid is mixed with the ink, it has an adverse effect on the ink. Can be prevented.

  The proportion of glycol ethers in the entire cleaning liquid for an inkjet apparatus according to the present invention is, for example, preferably in the range of 1 to 40% by mass, more preferably in the range of 2 to 30% by mass, and particularly preferably 5 to 20% by mass. % Range. If the glycol ether is less than 1% by mass, sufficient wettability and penetrability of the color material on the paper surface may not be obtained. If the glycol ether is more than 40% by mass, the blending amount is too large, and bleeding or beading may occur. May cause dating. By adding glycol ethers in the range of 1 to 40% by mass, the wettability and penetrability of the color material on the paper surface can be improved. Moreover, the range of 5-20 mass% is especially preferable from a viewpoint of the characteristic, the compounding quantity of another solvent, and the viewpoint of the cost of ink.

<Antioxidant>
The cleaning liquid for inkjet printing according to the present invention may contain an antioxidant. By containing the antioxidant, the effect of preventing the oxidation is improved, and the adverse effect on the ink refillability after the cleaning can be suppressed together with the cleaning around the head.

  Examples of the antioxidant include butylhydroxytoluene, phenolic antioxidants (including hindered phenolic antioxidants), amine antioxidants, sulfur antioxidants, phosphorus antioxidants, and the like. .

  Examples of phenolic antioxidants (including hindered phenolic antioxidants) include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4 , 4′-Butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) Propionyloxy] ethyl] 2,4,8,10-tetrixaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4- Hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane and the like.

  Examples of amine-based antioxidants include phenyl-β-naphthylamine, α-naphthylamine, N, N′-di-sec-butyl-p-phenylenediamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol, butylhydroxyanisole, 2,2′-methylenebis (4 -Methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), tetrakis [methylene- 3 (3,5-di-tert-butyl-4-dihydroxyphenyl) propionate] methane, Examples include 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane.

  Examples of the sulfur-based antioxidant include dilauryl 3,3′-thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl β, β′-thiodipropionate, 2-mercaptobenzimidazole, dilauryl sulfide and the like can be mentioned.

  Examples of phosphorus antioxidants include triphenyl phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl trithiophosphite, and trinonylphenyl phosphite.

  Of these, butylhydroxytoluene is preferred.

<Surfactant>
The cleaning liquid for an inkjet device according to the present invention may contain a surfactant. As the surfactant, the following general formula (1)
R—O— (CH ₂ CH ₂ O) _x — (CH ₂ CH (CH ₂ ) CH ₂ O) _y —H (1)
(In the formula (1) R: a branched _{- (CH 2) m -CH 3} , m = 3~15 integer, x = 6 to 15 integer, an integer of y = 1 to 5)
The polyoxyalkylene monoalkyl ether shown in FIG.

  By including such a surfactant, it is possible to obtain a cleaning liquid that has excellent cleaning properties, suppresses damage and wear to the ink flow path, and has high ejection stability when refilled with ink.

  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 3.3% with respect to the total amount of the cleaning liquid for an inkjet device according to the present invention. 0% by mass. When the content is abnormal by 0.1% by mass, an excellent cleaning effect can be obtained, and when the content is 10% by mass or less, the viscosity of the cleaning liquid can be prevented from increasing. If the viscosity is high, problems such as detergency, bubbles / defoaming properties, and wettability occur.

  In the 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.

  Among the surfactants represented by the general formula (1), those having an HLB of 10 to 13 are more preferable. If HLB is 10 or more, the cloud point is not low, so that the solubility at normal temperature is excellent and the performance can be more effectively exhibited. If the cloud point is low, the surfactant precipitates from the cleaning liquid when the temperature rises in the storage environment after cleaning, so the agglomeration is promoted by deteriorating the dispersion state of the ink pigment dispersion contained in the cleaning residual liquid. However, if the HLB is 10 or more, this can be prevented. Moreover, by making HLB 13 or less, it prevents that the hydrophilic property of surfactant becomes high too much. If the hydrophilicity is too high, the penetrating power will be reduced and the ink adhering to the ink flow path will not be able to penetrate, and the cleaning effect will be reduced. it can.

  Further, when the oxyethylene chain length x is less than 6, the oxypropylene chain y is 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.

  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 the state in which the ink is extremely diluted with the cleaning liquid. The environment has changed drastically, making it difficult to maintain dispersion stability. However, the dispersion stability can be maintained by including the surfactant represented by the general formula (1) in the cleaning liquid for an inkjet device according to the present invention.

  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.

<Viscosity>
The viscosity of the cleaning liquid for an inkjet device according to the present invention is not particularly limited, but is preferably a viscosity close to that of ink, for example, the viscosity at 25 ° C. is 2.0 mPa · s or more and 10 mPa · s or less. Is more preferable. Inks often have the above viscosity. By setting the cleaning liquid to such a viscosity, even if the cleaning liquid is mixed with the ink, the viscosity of the ink can be prevented from being lost.

  A low-viscosity cleaning liquid 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 nozzle completely replaced with the cleaning liquid is easy to flow, and the remaining nozzle remains difficult to flow, and the nozzle cannot be completely cleaned.

  Therefore, it is preferable for cleaning in the head to bring the physical properties of the cleaning liquid closer to the physical properties of the ink, and the viscosity at 25 ° C. is preferably 2.0 mPa · s or more, more preferably 2.5 mPa · s or more. The difference in viscosity from the ink in the head can be further reduced, and the head can be washed more uniformly.

  Moreover, when the liquid viscosity is higher, the pigment dispersion can be prevented from settling when mixed with the pigment ink, 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 for an ink jet apparatus according to the present invention, if the viscosity exceeds 15 mPa · s, the cleaning performance may be deteriorated. For this reason, it is preferable that it is 15 mPa * s or less, and it is more preferable that it is 10 mPa * s or less.

  From the above, particularly preferable results can be obtained when the viscosity is 2.0 mPa · s or more and 10 mPa · s or less, more preferably 2.5 mPa · s or more and 10 mPa · s or less.

  The viscosity of the inkjet apparatus cleaning liquid according to the present invention can be adjusted by, for example, blending an appropriate amount of glycerin or glycol ether. These solvents have a higher viscosity than water, and the desired viscosity can be adjusted by the blending amount.

<Additives>
In addition to the components described above, the cleaning liquid for an inkjet device according to the present invention may contain an additive as long as the effects of the present invention are not impaired. Examples of the additive include, but are not limited to, antiseptic / antifungal agents, pH adjusters, chelating agents, rust preventives, penetrants and the like.

  Examples of antiseptic / antifungal agents include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol 1-oxide sodium, sodium benzoate, sodium pentachlorophenol and the like.

  The pH adjuster is more preferably one that does not adversely affect the cleaning liquid to be prepared, does not damage the ink flow path of the ink jet apparatus, and can adjust the pH to a desired value.

  For example, amines, alkali metal hydroxides, quaternary compound hydroxides, alkali metal carbonates are used when adjusting to basic, and inorganic acids and organic acids are used when adjusting to acid.

  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, coumaric acid, thiophene carboxylic acid, nicotinic acid, carborane acid, or derivatives of these compounds.

  The pH adjuster is not limited to the compounds listed here. As the pH adjusting agent, those having an optimal pKa can be appropriately used in accordance with the characteristics corresponding to the pH fluctuation of the ink, and one kind may be used alone, or two or more kinds may be used in combination. Moreover, you may use a Buffer agent together. 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, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and benzotriazole.

  The penetrant may be added as necessary to supplement the penetrability of the surfactant or organic solvent. Such penetrant is more preferably a polyol having a solubility in water at 20 ° C. of 0.2% by mass or more and less than 5.0% by mass. In other words, the inkjet printing cleaning liquid according to the present invention has a penetrating agent in addition to the polyol having a solubility in water of 10 wt% or less in the standard state (25 ° C., 1 atm) to be contained for the purpose of reducing the amount of dissolved oxygen. A polyol as an agent may be included.

  Among such polyols, examples of the aliphatic diol include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, and 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 -1,2-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. That is, these polyols function well both as penetrants and as those that reduce the amount of dissolved oxygen.

  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. If the addition amount is 4.0% by mass or less, the dispersion stability of the pigment dispersion of the ink to be cleaned is not impaired. That is, problems such as aggregation of the dispersion, erosion of the ink flow path member, and swelling and elution of the adhesive can be suppressed.

<Ink>
The ink used in the ink jet device to be cleaned by the ink jet device cleaning liquid according to the present invention is not particularly limited, and can be applied to ink jet devices using various inks.

  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.

  The ink uses a titanium oxide dispersion as a pigment, a binder resin that is included in a latex ink to form an emulsion, or colored resin fine particles obtained by adding a water-insoluble or hardly soluble coloring material to resin fine particles. In this case, since the state after the head cleaning is a state in which the ink is extremely diluted with the cleaning liquid, the environment around the pigment has changed greatly, and it is difficult to maintain the dispersion stability. However, the cleaning liquid for an ink jet apparatus according to the present invention, particularly the cleaning liquid adjusted to the properties of the ink by selecting the above-mentioned water-soluble organic solvent and glycol ethers, adjusting the viscosity, etc. is suitable for an ink jet apparatus using such an ink. Can also be suitably used.

  The ink may contain water, a water-soluble organic solvent, glycol ethers, and the like. These properties are preferably close to those contained in the cleaning liquid for an ink jet apparatus according to the present invention, and the description is also in accordance with the description given for the cleaning liquid for an ink jet apparatus according to the present invention.

[Color material]
As for the coloring material contained in the ink, a pigment is mainly used from the viewpoint of weather resistance. However, a dye may be contained for the purpose of adjusting the color tone and within a range in which 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. Of these pigments, those having good affinity with water are particularly preferably used.

  Specific examples of black pigments that are more preferably used include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron (C.I. Pigment black 11), metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).

  Specific examples of color pigments that are more preferably used include 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 described in The Color Index, 3rd edition (The SoC. I. of of Dyers and Colorists, 1982).

  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 treatment using hypohalous acid and / or a salt thereof. Or the like is used. Among them, 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. Can be printed easily. 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 polymer fine particles. 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, as acid dyes and food dyes, C.I. I. . Acid Yellow 17, 23, 42, 44, 79, 142 C.I. 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. I. . Acid Blue 9, 29, 45, 92, 249; C.I. I. . Acid Black 1, 2, 7, 24, 26, 94; C.I. I. . Food Yellow 2, 3, 4; I. . Food Red 7, 9, 14C. I. . Food black 1, 2 etc. are mentioned.

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

  Examples of basic dyes include C.I. 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. 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; 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; I. . Basic black 2, 8 etc. are mentioned.

  Examples of reactive dyes include C.I. I. . Reactive Black 3, 4, 7, 11, 12, 17; I. . Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67; C.I. I. . Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97; C.I. I. . Reactive blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95 and the like.

  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 3 to 12%.
It is about mass%.

[Titanium oxide]
The ink used in the inkjet apparatus to be cleaned with the cleaning liquid for an inkjet apparatus according to the present invention may contain titanium oxide as a coloring material. The ink-jet apparatus cleaning liquid according to the present invention can also be suitably used for inks that easily form a film.

  Titanium oxide includes a rutile type and an anatase type, but is not particularly limited as long as it is within the characteristics that can be used as a coloring material.

  The average particle diameter is preferably 10 to 80 nm. The reason for this is that the specific gravity of titanium oxide is 4 to 5, an average of about 4.5, and is easy to settle. This is because the dispersion stability is further improved by reducing the particle size and increasing the self-dispersibility.

  Titanium oxide has three crystal forms: anatase (Anatase), rutile (Rutile) and brookite (Brookite). Of these, rutile and anatase are used industrially, while brookite is only taken up academically and has no industrial use.

  As for the arrangement of atoms in the titanium oxide crystal, six O atoms are coordinated around one Ti atom in the three crystal forms, and an octahedral ridge is formed by the O atoms. A rutile crystal has a structure in which two edges of an octahedron are shared and extend in a chain shape in the c-axis direction. Considering the space where the electron cloud spreads, a structure in which Ti atoms are sandwiched between gaps filled with large O atoms is considered.

  Rutile is an octahedral two-ridge shared chain structure in the c-axis direction as described above, but brookite is a three-ridge shared structure and anatase is a four-ridge shared structure.

The crystal unit cell unit cell has a structure containing two chemical units of rutile TiO ₂ , eight brookites and four anatases. The unit cell and crystal system data for three crystals are shown in Table 1 below. Rutile and anatase are tetragonal and brookite is orthorhombic. The volume per mole increases in the order of rutile, brookite, and anatase.

  Pauling's electronegativity is widely used for the ionicity and covalentness of chemical bonds of crystal constituent atoms. The ionicity of the Ti-O bond is reported to be 50% by Kiriyama, 43% by Grant, 63% by Beohm (titanium oxide-physical properties and applied technology-Kiyono Manabu Gihodo Publishing Co., Ltd.) Sharedness is considered to be a nearly half bond. Further, it is said that the ionicity decreases as the number of shared octahedral edges increases, and the ionicity decreases in the order of rutile, brookite, and anatase, and the sharing becomes stronger.

As for the chemical properties of titanium oxide, both anatase and rutile are soluble in hydrofluoric acid, hot concentrated sulfuric acid and dissolved alkali salts, but not in other acids, alkalis, water, organic solvents and the like. Further, a highly reactive gas such as HF, SO ₃ , Cl ₂ , and H ₂ S does not react with titanium oxide at room temperature and normal pressure, but reacts with HF at a high temperature to become TiF ₄ . Furthermore, it reacts with a halogen such as Cl _{2 at a} high temperature in the presence of a reducing agent to produce a titanium halide such as TiCl ₄ . Further, it is reduced with H ₂ , CO ₂ or the like at a high temperature to change to a lower oxide.

  Titanium oxide may react with other substances under special conditions like this, but it is extremely stable under normal use conditions, and there is no danger of combustion or explosion.

  In addition, since both the sulfuric acid method and the chlorine method are subjected to heat treatment at 800 to 1100 ° C. in the manufacturing process, titanium oxide itself is essentially not deteriorated by heating at 800 ° C. or less.

  The physical properties of titanium oxide are as follows.

(1) Electrical conductivity Titanium oxide is a complete insulator at room temperature, but acts as an n-type semiconductor when appropriate energy is applied from outside such as heating or ultraviolet irradiation.

(2) Thermal transition Among the three crystal forms of titanium oxide, rutile is the most stable, and anatase and brookite are transformed into rutile by heating. In the absence of a transfer control agent or accelerator, anatase transfers to rutile at 915 ± 15 ° C or higher, and brookite transfers to rutile at 650 ° C or higher.

  Since this reaction is irreversible, it does not transfer to anatase or brookite. Rutile melts at 1825 ° C. when further heated.

  Titanium oxide is preferably ultrafine titanium oxides TTO-51 (20 nm) and TTO-55 (35 nm) from Ishihara Sangyo, and various materials are commercially available from Fuji Titanium and DuPont.

  In addition, a pigment in which at least one hydrophilic group is bonded to the pigment surface directly or via another atomic group may be used. It can be stably dispersed without using a dispersant.

  As the pigment having a hydrophilic group introduced on the surface, those having ionicity are preferable, and those having an anionic charge or those having a cationic charge are suitable.

Examples of the anionic hydrophilic group, for _{example, -COOM, -SO 3 M, -PO} 3 HM, -PO 3 M 2, -SO 2 NH 2, -SO 2 NHCOR ( where, M in the formula is a hydrogen atom, R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. It is done. In the present invention, among these, it is particularly preferable to use a pigment having —COOM or —SO ₃ M bonded to the surface.

  Examples of a method for obtaining an anionically charged pigment include a method of oxidizing a pigment with sodium hypochlorite, a method of sulfonation, a method of reacting a diazonium salt, and the like.

  As the hydrophilic group charged to the cation, for example, a quaternary ammonium group can be used. More preferably, a pigment in which at least one of the quaternary ammonium groups listed below is bonded to the pigment surface is used.

  A pigment dispersion in which a pigment is dispersed in an aqueous medium with a dispersant can also be used. As a preferable dispersant, a known dispersant used for preparing a pigment dispersion can be used, and examples thereof include the following.

Polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer Polymer, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styne-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic Acid copolymer-alkyl acrylate ester copolymer, styrene-maleic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate -Maleic acid ester copolymer, vinyl acetate Rotonic acid copolymer, vinyl acetate-acrylic acid copolymer, etc.

  Further, the nonionic or anionic dispersant used for dispersing the pigment can be appropriately selected according to the pigment type or the ink formulation. For example, as the nonionic dispersant, polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene Polyoxyethylene alkyl ethers such as oxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl phenyl ethers such as polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene α Naphthyl ether, polyoxyethylene β naphthyl ether, polyoxyethylene monostyryl phenyl ether, polyoxyethylene distyryl phenyl ether, polyoxyethylene Examples thereof include xylethylene alkyl naphthyl ether, polyoxyethylene monostyryl naphthyl ether, polyoxyethylene distyryl naphthyl ether, polyoxyethylene polyoxypropylene block copolymer, and the like. Further, a dispersant obtained by replacing a part of each polyoxyethylene with polyoxypropylene, and a dispersant obtained by condensing a compound having an aromatic ring such as polyoxyethylene alkylphenyl ether with formalin or the like can also be used.

  The HLB of the nonionic dispersant is preferably 12 or more and 20.5 or less, more preferably 13 or more and 20 or less. If the HLB is 12 or more, the dispersion stability is good because the dispersant is well adapted to the dispersion medium. If the HLB is 20.5 or less, the dispersant is easily adsorbed to a pigment such as titanium oxide. Dispersion stability is improved.

  Furthermore, a resin-coated colorant can also be suitably used as titanium oxide. This will be described below.

  The colorant is composed of a polymer emulsion in which titanium oxide is contained in polymer fine particles. In the present specification, “containing titanium oxide” means either or both of a state in which titanium oxide is enclosed in polymer fine particles and a state in which titanium oxide is adsorbed on the surface of the polymer fine particles. In this case, it is not necessary for all of the titanium oxide blended in the ink to be enclosed or adsorbed in the polymer fine particles, and the titanium oxide may be dispersed in the emulsion. Such titanium oxide is not particularly limited as long as it is water-insoluble or hardly water-soluble and can be adsorbed by a polymer.

<Latex ink>
The cleaning liquid for an ink jet apparatus according to the present invention can also be suitably used for an ink jet apparatus using latex ink. Hereinafter, the binder resin that is emulsion or suspended in the latex ink is referred to as “polymer latex”. A water-dispersible resin is preferably used as the polymer latex contained in the ink.

  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. Further, it may be used as a composite resin by being used as a copolymer, and any of a single phase structure type, a core shell type, and a power feed type emulsion 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. Particularly suitable are ionomers of polyester resins and polyurethane resins, and emulsions of resin particles obtained by emulsion and suspension polymerization of unsaturated monomers. In the case of emulsion polymerization of an unsaturated monomer, by reacting in water to which an unsaturated monomer, a polymerization initiator, and a surfactant, a chain transfer agent, a chelating agent, a pH adjusting agent and the like are added, Since a resin emulsion is obtained, a water-dispersible resin can be easily obtained. Therefore, since the resin configuration can be easily changed, it is easy to make a desired property. Examples of unsaturated monomers that can be used in emulsion and suspension polymerization include unsaturated carboxylic acids, (meth) acrylic acid ester monomers, (meth) acrylic acid amide monomers, and aromatic vinyl monomers. , Vinylcyan compound monomers, vinyl monomers, allyl compound monomers, olefin monomers, diene monomers, oligomers having unsaturated carbon, and the like. These may be used alone or in combination of two or more. 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 and the like ((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, acryloxyethyl trimethyl ammonium salt, and the like.

(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, tetramethylol methane tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate.

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

(Aromatic vinyl monomers)
Styrene, α-methylstyrene, vinyltoluene, 4-t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene, divinylbenzene and the like.

(Vinyl cyanide monomers)
Acrylonitrile, methacrylonitrile, etc.

(Allyl compound monomers)
Allylsulfonic acid salt, allylamine, allyl chloride, diallylamine, diallyldimethylammonium salt and the like.

(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 and the like.

(Oligomers with unsaturated carbon)
Styrene oligomer having methacryloyl group, styrene-acrylonitrile oligomer having methacryloyl group, methyl methacrylate oligomer having methacryloyl group, dimethylsiloxane oligomer having methacryloyl group, polyester oligomer having acryloyl group.

  By using these monomers singly 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 that purpose, the minimum film-forming temperature (MFT) of the water-dispersible resin, that is, the binder resin that is emulsified or suspended in the latex ink, is more preferably normal temperature or lower, and further preferably 20 ° C. or lower. 0 ° C. or lower is particularly preferable. 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]
The ink may contain a surfactant. Examples of the surfactant include an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant. A surfactant that does not impair the dispersion stability may be 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 those exemplified here. Further, one type of surfactant may be used, or a plurality of types may be mixed and used. One type of surfactant may not be easily dissolved in the ink, but may be solubilized by mixing and exist stably.

  The amount of the surfactant is more preferably 0.01 to 5.0% by mass, and preferably 0.5 to 2.0% by mass with respect to the total amount of the ink in order to satisfactorily exert the permeability effect. Is more preferable. 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, with some surfactants, the solubility of the surfactant is insufficient during drying, and precipitation occurs, or the viscosity increases due to the influence of the surfactant. May cause.

<Antifoaming agent>
The ink may contain an antifoaming agent. As the antifoaming agent, for example, a commonly used antifoaming agent can be used. These include silicone antifoaming agents, polyether antifoaming agents, fatty acid ester antifoaming agents, and the like, which may be included singly or in combination. Among these, a silicone antifoaming agent is more preferable in terms of excellent foam 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 modified silicone antifoaming agents 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 acid esters. Modified silicone antifoaming agent, alkylene oxide modified silicone antifoaming agent and the like can be mentioned.

  Among these, a self-emulsifying type silicone antifoaming agent, an emulsion type silicone antifoaming agent and the like are preferable in consideration of use in an ink that is an aqueous medium.

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

  The content of the antifoaming agent in the ink is not particularly limited. However, since there are many antifoaming agents that do not completely dissolve in the ink and there is a high possibility of separation and precipitation, it is better not to add them as much as possible. However, if foaming occurs at the time of filling, the filling properties deteriorate, so it is preferable to use the minimum amount. For example, 0 to 3.0 mass% is more preferable, and 0 to 0.5 mass% is more preferable.

  Some antifoaming agents contain inorganic fine particles from the viewpoint of enhancing the bubble breaking effect, but it is preferable not to use them for ink.

<Inkjet device>
Various types of apparatuses can be used as the inkjet recording apparatus to be cleaned by the inkjet apparatus cleaning liquid according to the present invention. For example, a piezoelectric element is used as pressure generating means for pressurizing ink in the ink flow path, and a diaphragm that forms the wall surface of the ink flow path is deformed to change the volume in the ink flow path to discharge ink droplets. Type (refer to Japanese Patent Laid-Open No. 2-51734), so-called thermal type that generates bubbles by heating ink in an ink flow path using a heating resistor (see Japanese Patent Laid-Open No. 61-59911). The diaphragm and the electrode forming the wall surface of the ink flow path are opposed to each other, and the diaphragm is deformed by an electrostatic force generated between the vibration plate and the electrode, thereby changing the volume of the ink flow path and An electrostatic type that discharges droplets (see Japanese Patent Application Laid-Open No. 6-71882) can be used. Any of them can be suitably cleaned with the cleaning liquid for an ink jet apparatus according to the present invention.

  The cleaning liquid for an inkjet device according to 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.

<Washing method>
In the inkjet device cleaning method according to the present invention, the cleaning liquid for an inkjet device according to the present invention is passed through an inkjet device in which an ink supply path is filled with ink.

  As a specific cleaning method, a method other than using the cleaning liquid for an inkjet apparatus according to the present invention is not particularly limited.

  The step of supplying and discharging the cleaning liquid for an inkjet device according to the present invention into the ink flow path may be repeated.

  For example, by using a supply / suction mechanism of the inkjet apparatus main body, a method of repeatedly supplying and discharging the cleaning liquid into the ink flow path from the cartridge containing the cleaning liquid for the inkjet apparatus according to the present invention, or pressurizing the cleaning liquid container from the outside Examples thereof include a method of supplying a cleaning liquid and a method of sucking from the head side using an external pump.

  In any method, by passing the cleaning liquid for an ink jet apparatus according to the present invention through an ink jet apparatus in which the ink supply path is filled with ink, and replacing the liquid in the ink supply path with the cleaning liquid, The inkjet recording apparatus can be cleaned.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in the embodiments are also included. It is included in the technical scope of the present invention.

  Hereinafter, although the Example and comparative example of this invention are shown, this invention is not limited to these. In addition, the amount of each component described in the examples is based on weight.

<Adjustment of cleaning liquid>
The cleaning liquid was adjusted according to the following procedure.

  First, a pH adjuster, a surfactant, and water were mixed and dissolved uniformly. The water-soluble organic solvent was mixed there, and it stirred for 1 hour, and mixed 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 based on the following composition using the above method. In addition, the unit of the numerical value which shows the following component ratios is the mass%.

Example 1
3-methyl-1,3-butanediol 12 wt% (solid content)
Glycerin 10wt%
2-pyrrolidone 5wt%
Diethylene glycol isobutyl ether 20wt%
2-ethyl-1,3-hexanediol 4wt%
Surfactant with branching EO / PO (Emulgen Kao) 1wt%
Antioxidant Butylhydroxytoluene 0.5wt%
2-Amino-2-ethyl-1,3-propanediol 0.1 wt%
Ion exchange water was added to make 100%.

Example 2
1,3-butanediol 12wt% (solid content)
Glycerin 13wt%
2-pyrrolidone 5wt%
Triethylene glycol isobutyl ether 20wt%
2,2,4-Trimethyl-1,3-pentanediol 5wt%
Surfactant Branched EO / PO (Leox Kao) 1wt%
Antioxidant Butylhydroxytoluene 0.5wt%
Triethanolamine 0.1wt%
Ion exchange water was added to make 100%.

Example 3
Glycerin 20wt% (solid content)
Diethylene glycol isobutyl ether 20wt%
2-ethyl-1,3-hexanediol 5wt%
Surfactant with branching EO / PO (Emulgen Kao) 1wt%
Antioxidant Butylhydroxytoluene 0.5wt%
Triethanolamine 0.1wt%
Ion exchange water was added to make 100%.

Example 4
3-methyl-1,3-butanediol 10 wt% (solid content)
Glycerin 15wt%
Triethylene glycol isobutyl ether 20wt%
2-ethyl-1,3-hexanediol 5wt%
Surfactant with branching EO / PO (Emulgen Kao) 1wt%
Antioxidant Butylhydroxytoluene 0.5wt%
Sodium hydroxide 0.1wt%
Ion exchange water was added to make 100%.

Example 5
1,6-hexanediol 10wt% (solid content)
Glycerin 13wt%
2-pyrrolidone 5wt%
Triethylene glycol isobutyl ether 20wt%
2,2,4-Trimethyl-1,3-pentanediol 4wt%
Surfactant Branched EO / PO (Leox Kao) 1wt%
Antioxidant Butylhydroxytoluene 0.5wt%
Sodium hydroxide 0.1wt%
Ion exchange water was added to make 100%.

Comparative Example 1
Glycerin 14wt% (solid content)
Dipropylene glycol 10wt%
Diethylene glycol isobutyl ether 10wt%
1,4-butanediol 10wt%
Surfactant with branching EO / PO (Emulgen Kao) 1wt%
Triethanolamine 0.1wt%
Ion exchange water was added to make 100%.

Comparative Example 2
3-methyl-1,3-butanediol 10 wt% (solid content)
2-methyl-2,4-pentanediol 10wt%
Glycerin 10wt%
Triethylene glycol isobutyl ether 16wt%
Surfactant with branching EO / PO (Emulgen Kao) 1wt%
Sodium hydroxide 0.1wt%
Ion exchange water was added to make 100%.

Comparative Example 3
1,3-butanediol 10wt% (solid content)
1,6-hexane-diol 5wt%
Glycerin 13wt%
2-pyrrolidone 5wt%
Triethylene glycol isobutyl ether 15wt%
Surfactant Branched EO / PO (Leox Kao) 1wt%
2-Amino-2-ethyl-1,3-propanediol 0.1 wt%
Ion exchange water was added to make 100%.

Comparative Example 4
Glycerin 12wt% (solid content)
1,5-pentanediol 18wt%
Diethylene glycol isobutyl ether 20wt%
Surfactant with branching EO / PO (Emulgen Kao) 1wt%
Triethanolamine 0.1wt%
Ion exchange water was added to make 100%.

Comparative Example 5
Glycerin 14wt% (solid content)
Dipropylene glycol 10wt%
1,6-hexanediol 5wt%
Diethylene glycol isobutyl ether 10wt%
3-methyl-1,5-pentadiol 10wt%
Surfactant with branch EO / PO (Leox Kao) 1wt%
Sodium hydroxide 0.1wt%
Ion exchange water was added to make 100%.

[Deaeration process]
The cleaning liquids of Examples 1 to 5 were adjusted so that the dissolved oxygen amount was in the range of 5 mg / l or less through the step of adjusting the residual oxygen amount. Specifically, using a hollow fiber membrane deaeration module manufactured by Mitsubishi Rayon Co., Ltd. until the dissolved oxygen amount is 1 mg / l or less at a deaeration vacuum pressure of 90 kPa (deaeration MAX using ULVAC DAP-6D). Deaeration was performed.

  As a result, the dissolved oxygen concentration of each cleaning solution was as shown in Table 2 below. The cleaning solutions thus prepared were used as the cleaning solutions of Examples 1 to 5 (Table 2).

  Further, among the cleaning liquids of Comparative Examples 1 to 5, 2 to 4 were similarly degassed through the degassing step until the dissolved oxygen amount became 1 mg / l or less.

[Color material adjustment]
Synthesis example of polymer graft coloring material Synthesis example 1 (titanium oxide dispersion)
(A) Synthesis of titanium oxide provided with an organic group having a vinyl group 300.0 g of ethanol and 20.0 g of deionized water were put into a 1 L glass reaction vessel, and acetic acid was added dropwise while stirring at 150 rpm. The pH was adjusted to 4.5.

  Next, after adding 200 g of titanium oxide R-960 (manufactured by Dupont) and stirring at 150 rpm for 30 minutes, a solution in which 20 g of 3- (trimethoxysilyl) propyl methacrylate was dissolved in 80 g of ethanol was added in about 1 hour. After dropping, the mixture was stirred at 60 ° C. for 4 hours.

  Next, the dispersion obtained by returning to room temperature and stirring was centrifuged at 5000 rpm for 30 minutes and decanted. The obtained white powder was charged with 400 mL of ethanol, stirred and redispersed, and then the obtained dispersion was centrifuged at 5000 rpm for 30 minutes and decanted. The obtained white powder was left to stand overnight, dried, and then vacuum-dried at 70 ° C. for 4 hours to obtain a surface-treated titanium oxide having no chargeable group (amino group) and having an organic group having a vinyl group added thereto. Obtained.

(B) Introduction of graft polymer chain onto titanium oxide particle surface (synthesis of grafted titanium oxide)
Next, 100.0 g of lauryl methacrylate, 300.0 g of paraffin hydrocarbon neothiozole (manufactured by Chuo Kasei Co., Ltd.), 96.0 g of the above-mentioned surface-treated titanium oxide, and 0.600 g of AIBN were put into a 1 L pressurized reaction vessel. After nitrogen substitution and pressurization with nitrogen to 0.1 MPa, dispersion was performed for 30 minutes while stirring at 300 rpm. Thereafter, the mixture was heated to 75 ° C. in about 1 hour and stirred at 75 ° C. for 7 hours.

  Next, the dispersion obtained by returning to room temperature and stirring was centrifuged at 10,000 rpm for 30 minutes and decanted. The obtained white powder was charged with 600 mL of isooctane, stirred and redispersed, and then centrifuged at 10,000 rpm for 30 minutes and decanted twice. Furthermore, after standing overnight and drying, it was vacuum-dried at 70 ° C. for 4 hours to obtain a polymer-grafted titanium oxide. When the grafted titanium oxide was subjected to thermogravimetric analysis, the weight loss was 9.3% (GT).

Synthesis example 2 (carbon black dispersion)
90 g of carbon black with a CTAB specific surface area of 150 m ² / g and DBP oil absorption of 100 ml / 100 g is added to 3000 ml of 2.5 N normal sodium sulfate solution, stirred at a temperature of 60 ° C. and a speed of 300 rpm, and reacted for 10 hours for oxidation treatment. Was done. The reaction solution was filtered, and the carbon black separated by filtration was neutralized with a sodium hydroxide solution and subjected to ultrafiltration. The obtained carbon black (G-K) was washed with water, dried, and dispersed in pure water to 20% by weight.

Synthetic example of polymer inclusion color material Synthetic example 3
After sufficiently replacing the inside of the 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube and dropping funnel with nitrogen gas, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toagosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were charged, and the temperature was raised to 65 ° C.

  Next, styrene 100.8 g, acrylic acid 25.2 g, lauryl methacrylate 108.0 g, polyethylene glycol methacrylate 36.0 g, hydroxyethyl methacrylate 60.0 g, styrene macromer (manufactured by Toagosei Co., Ltd., trade name: AS-6) A mixed solution of 36.0 g, mercaptoethanol 3.6 g, azobisdimethylvaleronitrile 2.4 g and methyl ethyl ketone 18 g was dropped into the flask over 2.5 hours. After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added, and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a solid content concentration of 50%.

Synthesis example 4 (yellow pigment polymer inclusion dispersion)
28 g of the polymer solution prepared in Synthesis Example 3, 26 g of Pigment Yellow 74 pigment, 13.6 g of 1 mol / L potassium hydroxide solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water were sufficiently stirred and then kneaded using a three-roll mill. .

  The obtained paste was put into 200 g of ion-exchanged water and sufficiently stirred, and then methyl ethyl ketone and water were distilled off using an evaporator to obtain a cyan polymer fine particle dispersion (P-Ye). The particle size was 156 nm.

Synthesis Example 5 (Titanium oxide polymer inclusion dispersion)
After sufficiently stirring 28 g of the polymer solution prepared in Synthesis Example 3 and 26 g of titanium oxide (TTO-51 particle diameter 20 nm manufactured by Ishihara Sangyo), 13.6 g of 1 mol / L potassium hydroxide solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water. And kneading using a three-roll mill. The obtained paste was put into 200 g of ion-exchanged water and sufficiently stirred, and then methyl ethyl ketone and water were distilled off using an evaporator to obtain a white polymer fine particle dispersion (PT). The particle size was 50 nm.

Production Example 1 of Resin Dispersed Color Material
150 g of titanium oxide (TTO-55 manufactured by Ishihara Sangyo Co., Ltd., particle size 35 nm), Solsperse 43000 (manufactured by Lubrizol), 3.0%, Solsperse 44000 (manufactured by Lubrizol), 3.0%, distilled water After mixing 738 g and pre-dispersing this mixture, it was circulated and dispersed for 20 hours in a disk-type bead mill (Shinmaru Enterprises KDL type, media: 0.3 mmφ zirconia ball used), and titanium oxide (RT) A pigment dispersion was obtained.

Production Example 2 (Dimethylquinacridone pigment dispersion)
C. I. 150 g of Pigment Red 122, Solsperse 43000 (manufactured by Lubrizol), 3.38%, Solsperse 44000 (manufactured by Lubrizol), 3.38%, and 738 g of distilled water were mixed, and this mixture was pre-dispersed. Then, it was circulated and dispersed for 20 hours in a disk-type bead mill (Shinmaru Enterprises KDL type, media: 0.3 mmφ zirconia ball used) to obtain a dimethylquinacridone pigment dispersion (RM).

  Next, a synthesis example of the polymer latex used in the present invention is shown.

Synthesis Example 6
After fully replacing the inside of the flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel with nitrogen gas, 10 g of Aqualon RN-20 (Daiichi Kogyo Seiyaku), 1 g of potassium persulfate and pure 286 g of water was charged and the temperature was raised to 65 ° C. Next, 150 g of methyl methacrylate, 100 g of 2-ethylhexyl acrylate, 20 g of acrylic acid, 20 g of vinyltriethoxysilane, Aqualon RN-2010 g, 4 g of potassium persulfate, 10 g of Aqualon RN-20, 4 g of potassium persulfate and pure water 398. 3 g of the mixed solution was dropped into the flask over 2.5 hours. The mixture was further heated and aged at 80 ° C. for 3 hours and then cooled, and the pH was adjusted to 7 to 8 with potassium hydroxide. The particle diameter of the resin measured using Microtrac UPA was 130 nm. The minimum film-forming temperature (MTF) was 0 ° C. (P-1).

Synthesis example 7
After fully replacing the inside of the flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel with nitrogen gas, 10 g of Aqualon RN-20 (Daiichi Kogyo Seiyaku), 1 g of potassium persulfate and pure 286 g of water was charged and the temperature was raised to 65 ° C. Next, 150 g of methyl methacrylate, 100 g of 2-ethylhexyl acrylate, 20 g of acrylic acid, 40 g of hexyltrimethoxysilane, Aqualon RN-2010 g, 4 g of potassium persulfate, 10 g of Aqualon RN-20, 4 g of potassium persulfate and pure water 398. 3 g of the mixed solution was dropped into the flask over 3 hours. The mixture was further heated and aged at 80 ° C. for 3 hours and then cooled, and the pH was adjusted to 7 to 8 with potassium hydroxide. The particle diameter of the resin measured using Microtrac UPA was 148 nm. The minimum film-forming temperature (MTF) was 0 ° C. (P-2).

Synthesis example 8
After fully replacing the inside of the flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel with nitrogen gas, 100 g of pure water, 3 g of sodium dodecylbenzenesulfonate, and 1 g of polyethylene glycol nonylphenyl ether were added. First, 1 g of ammonium persulfate and 0.2 g of sodium hydrogen sulfite were added, and the temperature was raised to 60 ° C. Next, 30 g of butyl acrylate, 40 g of methyl methacrylate, 1:20 g of butyl methacrylate, 10 g of vinylsilane triol potassium salt and 1 g of 3-methacryloxypropylmethyldimethoxysilane were added dropwise to the flask over 3 hours. At this time, polymerization was carried out by adjusting the polymerization reaction solution to pH 7 with an aqueous ammonia solution. The particle diameter of the resin measured using Microtrac UPA was 160 nm. The minimum film forming temperature (MTF) was 0 ° C. (P-3).

[Latex ink preparation]
Each of the inks of Examples and Comparative Examples was prepared using the prepared six types of pigment dispersions and polymer latex. An ink composition was prepared as follows and adjusted with a 10% aqueous solution of lithium hydroxide so that the pH was 9. Then, it filtered with the membrane filter whose average hole diameter is 0.8 micrometer, and obtained the ink composition.

Ink preparation example 1
9 wt% (solid content) of polymer grafted titanium oxide (GT) synthesized in Synthesis Example 1
Polymer latex (P-1) (solid content 45%) 8wt%
3-methyl-1,3-butanediol 12wt%
Glycerin 10wt%
2-pyrrolidone 2wt%
Diethylene glycol isobutyl ether 10wt%
2-ethyl-1,3-hexanediol 2wt%
Polyalkylene glycol surfactant (Asahi Denka) 1wt%
Amine compound 0.1wt%
Ion exchange water was added to make 100%.

Ink preparation example 2
Polymer graft carbon black (GK) synthesized in Synthesis Example 2 8 wt% (solid content)
Polymer latex (P-2) (45% solid content) 6 wt%
1,3-butanediol 10wt%
Glycerin 13wt%
2-pyrrolidone 1wt%
Triethylene glycol isobutyl ether 10wt%
2,2,4-Trimethyl-1,3-pentanediol 2wt%
Polyalkylene glycol surfactant (Asahi Denka) 1wt%
Amine compound 0.1wt%
Ion exchange water was added to make 100%.

Ink Preparation Example 3
Polymer-encapsulated yellow pigment (P-Ye) synthesized in Production Example 4 8 wt% (solid content)
Polymer latex (P-3) (solid content 45%) 10 wt%
Glycerin 20wt%
Diethylene glycol isobutyl ether 10wt%
2-ethyl-1,3-hexanediol 2wt%
Polyalkylene glycol surfactant (Asahi Denka) 1wt%
Amine compound 0.1wt%
Ion exchange water was added to make 100%.

Ink Preparation Example 4
Polymer-encapsulated titanium oxide (PT) synthesized in Synthesis Example 5 8 wt% (solid content)
Polymer latex (P-1) (solid content 45%) 5 wt%
3-methyl-1,3-butanediol 10wt%
Glycerin 15wt%
Triethylene glycol isobutyl ether 10wt%
2-ethyl-1,3-hexanediol 2wt%
Polyalkylene glycol surfactant (Asahi Denka) 1wt%
Amine compound 0.1wt%
Ion exchange water was added to make 100%.

Ink preparation example 5
Resin-dispersed titanium oxide (RT) produced in Production Example 1 8 wt% (solid content)
Polymer latex (P-2) (45% solid content) 6 wt%
1,6-hexanediol 10wt%
Glycerin 13wt%
2-pyrrolidone 1wt%
Triethylene glycol isobutyl ether 10wt%
2,2,4-Trimethyl-1,3-pentanediol 2wt%
Polyalkylene glycol surfactant (Asahi Denka) 1wt%
Amine compound 0.1wt%
Ion exchange water was added to make 100%.

Ink Preparation Example 6
Resin-dispersed quinacridone (RM) produced in Production Example 2 8 wt% (solid content)
Polymer latex (P-3) (45% solid content) 6 wt%
Glycerin 14wt%
Dipropylene glycol 10wt%
Diethylene glycol isobutyl ether 10wt%
2-ethyl-1,3-hexanediol 2wt%
Polyalkylene glycol surfactant (Asahi Denka) 1wt%
Amine compound 0.1wt%
Ion exchange water was added to make 100%.

<Uniformity as cleaning liquid>
The uniformity of the cleaning liquid was evaluated by allowing the cleaning liquid obtained by the above-mentioned method to stand for 1 hour, and visually observing the state of the liquid after standing.

Circle: Uniform state without separation or insoluble matter X: Part of the component is separated or insoluble matter is present and is in a 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.

Circle: Unclear whether or not separation is present. Triangle: Shading is observed. X: Separation is occurring. In addition, substances that cannot ensure uniformity as a cleaning liquid are not uniform when mixed with ink, and are therefore excluded from the evaluation.

<Evaluation of cleaning performance of cleaning liquid>
-Initial state setting Using an inkjet printer "JV5" (Mimaki Engineering Co., Ltd., product name), attach GEN5 (Ricoh Co., Ltd.) to the head, replace the ink supply path and ink in the head with pure water, and then A cartridge filled with the magenta ink obtained in the above production example instead of black and cyan ink, and a cartridge filled with the yellow ink obtained in the above production example instead of magenta and yellow ink are attached, and the head refreshing operation is performed after the filling operation. The ink supplied repeatedly and the ink in the head were replaced with the ink obtained in the above production example. Thereafter, a nozzle check pattern was printed, and a head refreshing operation was performed until there was no missing nozzle.

-Cleaning treatment After confirming that the nozzles of the inkjet printer were not missing, a cartridge filled with the cleaning solution was attached instead of all the cartridges, and the head refreshing operation was performed 6 times. Thereafter, the operation of the maintenance unit of the printer, suctioning 4.5 cc from each head, and refilling were repeated three times. After filling again, 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 performance The last suction cleaning solution was collected, and absorbance was measured at 280 nm for white (titanium oxide) ink, 255 nm for carbon black ink, 421 nm for yellow ink, and 563 nm for magenta ink. And the concentration (% by mass) of the colored fine particles in the collected cleaning liquid 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 components in the ink when it is mixed with the ink in the cleaning performance evaluation apparatus (inkjet printer), and the particle size A large precipitate is 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 inkjet printer “JV5” (product name, manufactured by Mimaki Engineering Co., Ltd.), GEN5 (produced by Ricoh Co., Ltd.) is attached to the head, and the inkjet printer is cleaned by the cleaning process described in the section <Evaluation of cleaning performance of cleaning liquid>. After leaving the nozzle surface with a moisture retention cap at 50 ° C. and 60% RH for one month, the ink cartridge filled with the yellow ink and magenta ink obtained in the above production example was attached, and the initial filling operation was performed. Was carried out. 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. Evaluation was performed at (maximum 8 times).

Circle: Head refreshing 2 times or less Triangle: 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 fluid, separation is performed by evaluating the mixing properties of cleaning fluid and ink. Cleaning liquids that cause stagnation were excluded from the evaluation due to nozzle clogging and filter clogging. The ink number represents ink production examples 1 to 5. 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.

  The present invention can be used for cleaning an inkjet apparatus.

Claims (10)

  A cleaning liquid for an ink jet apparatus, comprising a polyol having a solubility in water of 10 wt% or less in a standard state (25 ° C., 1 atm).   The amount of dissolved oxygen is 5 mg / l or less, The washing | cleaning liquid for inkjet devices of Claim 1 characterized by the above-mentioned.   The cleaning liquid for an ink jet apparatus according to claim 1 or 2, wherein the polyol is 2-ethyl-1,3-hexanediol or 2,2,4-trimethyl-1,3-pentanediol.   The cleaning liquid for an ink jet apparatus according to claim 1, further comprising an antioxidant, wherein the antioxidant is butylhydroxytoluene.   Including glycol ethers, wherein the glycol ethers are at least one selected from the group consisting of diethylene glycol diethyl ether, diethylene glycol isobutyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, and triethylene glycol monobutyl ether. The cleaning liquid for an inkjet device according to any one of claims 1 to 4. The following general formula (1)
R—O— (CH ₂ CH ₂ O) _x — (CH ₂ CH (CH ₂ ) CH ₂ O) _y —H (1)
(In the formula (1) R: a branched _{- (CH 2) m -CH 3} , m = 3~15 integer, x = 6 to 15 integer, an integer of y = 1 to 5)
The cleaning liquid for an ink jet apparatus according to claim 1, further comprising a polyoxyalkylene monoalkyl ether represented by the formula:   The cleaning liquid for an inkjet device according to any one of claims 1 to 6, wherein a viscosity at 25 ° C is 2.0 mPa · s or more and 10 mPa · s or less.   A cleaning method for an ink jet apparatus, comprising: passing the cleaning liquid for an ink jet apparatus according to any one of claims 1 to 7 through an ink jet apparatus having an ink supply path filled with ink.   9. The method for cleaning an ink jet apparatus according to claim 8, wherein the ink contains water, a water-soluble organic solvent, and a binder resin, and the binder resin is emulsion or suspended.   The method for cleaning an ink jet apparatus according to claim 8, wherein the ink further contains titanium oxide having an average particle diameter of 10 to 80 nm.