Maintenance method and recording device

Abstract

To provide a maintenance method that offers excellent cleaning performance (nozzle recovery) and uses a small amount of maintenance fluid. [Solution] A maintenance method according to one embodiment of the present invention is a maintenance method for a recording device having an inkjet head having a nozzle for dispensing an aqueous ink composition, comprising a settling step of placing the nozzle surface on which the nozzle of the inkjet head is formed in contact with an absorbent member containing a maintenance liquid.

Description

[Technical Field]

[0001] This invention relates to a maintenance method and a recording device. [Background technology]

[0002] Inkjet recording methods, which allow for the recording of high-resolution images with relatively simple equipment, are undergoing rapid development in various fields. However, because ink ejection problems can occur due to clogging of the inkjet head nozzles, various studies are being conducted on nozzle cleaning.

[0003] For example, Patent Document 1 describes a maintenance method in which maintenance fluid is applied to the nozzle surface or a wiping member, and the nozzle surface is wiped with the wiping member. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-154614 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, it was still not sufficient in terms of reducing the amount of maintenance fluid used and achieving better cleaning performance (nozzle recovery). [Means for solving the problem]

[0006] One aspect of the maintenance method according to the present invention is: A method for maintaining a recording device having an inkjet head with a nozzle for ejecting an aqueous ink composition, The process includes a settling step in which the nozzle surface of the inkjet head, on which the nozzle is formed, is placed in contact with an absorbent material containing maintenance fluid and left to stand.

[0007] One aspect of the recording device according to the present invention is: A recording device that is maintained by the maintenance method described in the above embodiment, The system comprises the inkjet head, the absorbent member, and the maintenance fluid. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic cross-sectional view showing the state in which the absorbing member is in contact with the nozzle forming surface. [Figure 2] A schematic cross-sectional view showing the state of suction from the nozzle of an inkjet head. [Figure 3] A schematic cross-sectional view illustrating an inkjet recording device. [Figure 4] A perspective view showing an example of the configuration around the carriage of an inkjet recording device. [Figure 5] Table 1 shows examples of maintenance fluid compositions. [Figure 6] Table 2 shows examples of ink composition. [Figure 7] Table 3 shows the evaluation results for each embodiment and each reference example. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below. The embodiments described below are examples of the present invention. The present invention is not limited in any way to the embodiments described below, and includes various modifications that can be implemented without changing the gist of the present invention. Not all of the configurations described below are necessarily essential to the present invention.

[0010] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, "(meth)acrylic" means acrylic or methacrylic, and "(meth)acrylate" means acrylate or methacrylate.

[0011] 1. Maintenance method The maintenance method according to an embodiment of the present invention is a maintenance method for a recording apparatus having an inkjet head having a nozzle that discharges an aqueous ink composition, and includes a standing step of standing with the nozzle surface of the inkjet head in contact with an absorption member containing a maintenance liquid.

[0012] When the nozzles of the inkjet head become clogged, ink ejection failure may occur, and it is necessary to clean the clogging by maintenance. In particular, since the aqueous ink composition may contain a fixing resin such as resin particles, when the ink dries, it solidifies at the nozzle, etc., and ejection failure of the nozzle is likely to occur.

[0013] As a conventional maintenance method, there is a method of immersing the nozzle surface in the liquid surface of the maintenance liquid filled in a cap, but this method requires a large amount of maintenance liquid, and the maintenance liquid is also likely to evaporate. In addition, an air layer is likely to occur between the liquid surface of the maintenance liquid and the ink in the nozzle, and the maintenance liquid may not penetrate to the ink inside the nozzle, and sufficient cleaning may not be performed. Also, in the method of attaching the maintenance liquid to the nozzle surface by spraying or the like, the maintenance liquid may not penetrate sufficiently inside the nozzle, and since the maintenance liquid evaporates easily immediately after adhering to the nozzle surface, the cleaning property is not sufficient.

[0014] Now, it has been found that excellent nozzle recoverability can be obtained by a maintenance method in which a maintenance liquid is contained in an absorption member capable of absorbing a liquid and the absorption member is allowed to stand while being in contact with the nozzle surface. In such a method, excellent nozzle recoverability can be obtained even with a smaller amount of maintenance liquid compared to the method of immersing the nozzle surface in the liquid surface of the maintenance liquid filled in a cap. In addition, since the maintenance liquid is contained in the absorption member, evaporation of the maintenance liquid can be suppressed, and the maintenance liquid can penetrate inside the nozzle.

[0015] The following describes each step of the maintenance method according to this embodiment.

[0016] 1.1 Standing process The maintenance method according to this embodiment includes a settling step in which the nozzle surface on which the nozzles of the inkjet head are formed is brought into contact with an absorbent member containing a maintenance fluid and left to stand.

[0017] Figure 1 shows a schematic cross-sectional view illustrating the state in which an absorbent member (cloth wiper) is in contact with the nozzle surface (nozzle-forming surface) of the inkjet head where the nozzles are formed. Figure 1 shows the state in which the absorbent member 21 is pressed against the nozzle-forming surface 222 of the inkjet head 2 in the direction of arrow F1.

[0018] 1.1.1 Absorbing material The absorbent material is not particularly limited as long as it can absorb and retain liquids such as maintenance fluid, and can be made of sponge, woven fabric or nonwoven fabric, etc. If the absorbent material is a fabric, there is no particular limit to the constituent fibers, but examples include natural fibers such as cellulose fibers and synthetic fibers such as polyester fibers. Among these, natural fibers are preferred, and cellulose fibers are more preferred. Cellulose fibers swell when exposed to water. Therefore, the maintenance fluid softens the fibers, which can reduce wear on the water-repellent film on the nozzle-forming surface. In addition, foreign matter tends to get trapped in the gaps between the swollen cellulose fibers, thus improving cleaning performance.

[0019] The absorbent material shown in Figure 1 is a long piece of fabric, with the absorbent material 21 being fed out from the first roll 22 before use and the absorbent material 21 being wound up from the second roll 23. This allows the new absorbent material 21 to come into contact with the nozzle forming surface 222 before use. Therefore, it is possible to prevent the nozzle forming surface 222 from being re-contaminated by the ink composition that has permeated the used absorbent material 21 by the used absorbent material 21 coming into contact with the nozzle forming surface 222 again.

[0020] 1.1.2 Method of applying maintenance fluid In the settling process, there are no particular limitations on the method of applying the maintenance fluid to the absorbent material. Examples include methods such as spraying, dripping, or coating the maintenance fluid to attach it to the nozzle surface or absorbent material, or impregnating the absorbent material with the maintenance fluid.

[0021] Therefore, the maintenance method according to this embodiment may involve applying maintenance fluid to the nozzle surface and then bringing the nozzle surface coated with maintenance fluid into contact with an absorbent member and leaving it to stand, or applying maintenance fluid to an absorbent member and then bringing the nozzle surface into contact with the absorbent member and leaving it to stand. With the maintenance method according to this embodiment, excellent nozzle recovery can be obtained regardless of which standing method is used.

[0022] The inkjet head 2 has a nozzle forming surface 222 on its lower side, where nozzles are formed. In a configuration in which maintenance fluid is applied to the nozzle surface and the nozzle surface with the maintenance fluid applied is brought into contact with an absorbent member and left to stand, for example, in Figure 1, the maintenance fluid 31 is applied to the nozzle forming surface 222 (nozzle surface) by spraying it with the second sprayer 25, and the absorbent member 21 is pressed against the nozzle forming surface 222 with the maintenance fluid 31 applied in the direction of arrow F1, thereby impregnating the absorbent member 21 with the maintenance fluid 31 and bringing the absorbent member 21 into contact with the nozzle forming surface 222 and leaving it to stand. The inkjet head 2 can be moved in the left-right direction in the diagram by a mechanism for moving the inkjet head (not shown). Maintenance is performed by applying maintenance fluid to the nozzle forming surface 222 of the inkjet head 2 when it is in the position of the inkjet head 2 on the left in the diagram, and then moving the inkjet head 2 to the position of the inkjet head 2 on the right in the diagram.

[0023] Furthermore, in an embodiment in which the maintenance liquid is applied to the absorbent member and the nozzle surface is brought into contact with the absorbent member to which the maintenance liquid is applied and left to stand, for example, in Figure 1, the maintenance liquid 31 can be applied to the absorbent member 21 by spraying the maintenance liquid 31 onto the first roll 22 on which the absorbent member 21 is wound using the first sprayer 24, or by applying the first roll 22 on which the absorbent member 21 is wound to a pool 26 of maintenance liquid 31, and the absorbent member 21 impregnated with the maintenance liquid 31 can be brought into contact with the nozzle forming surface 222 by pressing it in the direction of arrow F1 and left to stand.

[0024] The position at which the maintenance liquid 31 is applied to the absorbent member 21 before it reaches the nozzle forming surface 222 is not limited to the position shown in Figure 1. The maintenance liquid 31 may be applied to the absorbent member 21 as it is fed from the first roll 22 in the direction of arrow F2, at any stage before it reaches the nozzle forming surface 222. For example, it may be a position closer to the nozzle forming surface 222. For example, it may be a position immediately before the pressing member 40 that presses the absorbent member 21 in the direction of arrow F1.

[0025] The pressing member 40 moves in the direction of F1, pushing the absorbing member 21 upward in the direction of F1. The pressing member 40 is, for example, a plate-shaped member, and moves in the direction of F1 by a mechanism for moving the pressing member (not shown). Due to the movement, the absorbing member 21 is pushed upward in the direction of F1, comes into contact with the nozzle forming surface 222, and applies pressure to the nozzle forming surface 222. The absorbing member 21 can make surface contact with the nozzle forming surface 222. The standing process is performed with the absorbing member 21 in contact with the nozzle forming surface 222, without changing the relative position between the absorbing member 21 and the nozzle forming surface 222 in the left-right direction shown in the figure. This is the standing process. During periods when the settling process or the wiping process described later is not performed, the pressing member 40 may move in the opposite direction to F1 so that the absorbing member 21 does not come into contact with the nozzle forming surface 222.

[0026] During the settling process, the maintenance fluid content of the absorbent material is 10 mg / inch. 2Preferably, it is as above, 20 mg / inch 2 More preferably, it is as above, 30 mg / inch 2 Even more preferably, it is as above, 40 mg / inch 2 Particularly preferably, it is as above, 50 mg / inch 2 Even more particularly preferably. When the content of the maintenance liquid of the absorption member is particularly 30 mg / inch 2 or more, it tends to be more excellent in nozzle recovery property. The content of the maintenance liquid of the absorption member is the content of the maintenance liquid at the portion where the nozzle formation surface of the absorption member is in contact in the standing process. Also, the upper limit value of the content of the maintenance liquid of the absorption member during the standing process is not particularly limited, but preferably 200 mg / inch 2 or less, more preferably 150 mg / inch 2 even more preferably 100 mg / inch or less 2 even more preferably 80 mg / inch or less 2 particularly preferably 80 mg / inch or less.

[0027] 1.1.3 Standing In FIG. 1, the absorption member 21 is brought into contact with the nozzle formation surface 222 of the inkjet head 2 and pressed in the direction of arrow F1, and then left standing.

[0028] <� The pressing load of the absorption member 21 on the nozzle formation surface 222 is not particularly limited as long as the nozzle formation surface 222 is in contact with the absorption member 21, but preferably 8 gf / cm or more, more preferably 15 gf / cm or more, even more preferably 25 gf / cm or more, and particularly preferably 30 gf / cm or more. When the pressing load is within the above range, the absorption member absorbs ink from the nozzle, and the effect of sucking out ink from the nozzle is more exerted, and it tends to be more excellent in nozzle recovery property. On the other hand, the upper limit of the pressing load of the absorbing member 21 on the nozzle forming surface 222 is not particularly limited, but is preferably 300 gf / cm or less, more preferably 200 gf / cm or less, even more preferably 100 gf / cm or less, and particularly preferably 50 gf / cm or less. When the pressing load is within the above range, the preservation of the liquid-repellent film formed on the nozzle forming surface tends to be even better. The load referred to here is the value obtained by dividing the total load applied to the inkjet head 2 by the contact length (i.e., the average linear pressure). Furthermore, the contact length is the longitudinal contact length between the inkjet head 2 and the absorbent member 21, and if the nozzle plate cover and the absorbent member are in contact, that length is also included.

[0029] The resting time in the resting process is preferably 30 seconds or more, more preferably 1 minute or more, even more preferably 2 minutes or more, even more preferably 4 minutes or more, and particularly preferably 5 minutes or more. When the resting time in the resting process is within the above range, the nozzle recovery performance tends to be better. On the other hand, the standing time in the standing process is not limited, but is preferably 15 minutes or less, more preferably 10 minutes or less, even more preferably 7 minutes or less, and even more preferably 5 minutes or less. If the interval is too long, maintenance fluid may enter the nozzle channel and mix with the ink. However, if the standing time is within the above-mentioned range, this can be reduced or suppressed, which is preferable.

[0030] Furthermore, the maintenance method according to this embodiment may include a wiping step (described later) in which the nozzle surface is wiped with the absorbent material used in the standing step after the standing step. In other words, the absorbent material can be used for both the standing step and the wiping step. Wiping can be performed, for example, by moving the absorbent member 21 or the inkjet head 2 in the left-right direction in the figure while the absorbent member 21 is in contact with the nozzle forming surface 222.

[0031] 1.1.4 Maintenance fluid The components of the maintenance fluid are not particularly limited, but examples include water, organic solvents, surfactants, and neutralizing agents. The following describes each component contained in the maintenance fluid.

[0032] 1.1.4.1 Water The maintenance fluid is preferably water-based. Water-based maintenance fluids tend to redisperse solidified components of water-based ink compositions more easily, resulting in superior nozzle recovery.

[0033] "Aqueous" means that it contains at least water as a solvent component, and may contain water as the main solvent component.

[0034] Examples of suitable water include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water, which has reduced ionic impurities. Furthermore, using water sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can suppress the growth of bacteria and fungi when the maintenance fluid is stored for a long period of time.

[0035] The water content is preferably 50% by mass or more, more preferably 50 to 100% by mass, in the liquid medium component. Furthermore, it is preferably 60 to 95% by mass, more preferably 70 to 90% by mass, and even more preferably 75 to 85% by mass. The liquid medium refers to a solvent component such as water or an organic solvent. Furthermore, the water content is preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, relative to the total mass of the maintenance fluid. There is no particular upper limit to the water content, but for example, it is 100% by mass or less, preferably 99% by mass or less, and more preferably 90% by mass or less, relative to the total mass of the maintenance fluid.

[0036] 1.1.4.2 Organic Solvents The maintenance fluid may contain an organic solvent. Preferably, the organic solvent is a water-soluble organic solvent. "Water-soluble" means that its solubility in water at 20°C is greater than 10g / 100g of water.

[0037] Examples of organic solvents include esters, glycol ethers, cyclic esters, amides, alcohols, and polyhydric alcohols.

[0038] Esters include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate. Examples include glycol monoacetates such as methyl acetate and methoxybutyl acetate, and glycol diesters such as ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, and dipropylene glycol acetate propionate.

[0039] Examples of glycol ethers include monoethers or diethers of alkylene glycols. Examples of alkylene glycol monoethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, 3-methoxy-3-methylbutanol, and other alkylene glycol monoalkyl ethers. Examples of alkylene glycol diethers include alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0040] Examples of cyclic esters include cyclic esters (lactones) such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonalactone, ε-nonalactone, and ε-decanolactone, as well as compounds in which the hydrogen atoms of the methylene group adjacent to the carbonyl group are substituted with alkyl groups having 1 to 4 carbon atoms.

[0041] Examples of amides include cyclic amides and acyclic amides. Examples of amides include alkoxyalkylamides. Examples of cyclic amides include lactams. Examples of lactams include pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, and 1-(2-hydroxyethyl)pyrrolidine-2-one. Examples of alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, and 3-n-propoxy-N,N-dimethylpropionamide. Examples include propionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso-propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N-methylethylpropionamide, N,N-dimethylisobutyrateamide, etc.

[0042] Examples of alcohols include compounds in which one hydrogen atom of an alkane is replaced by a hydroxyl group. The alkane preferably has 10 or fewer carbon atoms, more preferably 6 or fewer, and even more preferably 3 or fewer. The alkane has 1 or more carbon atoms, preferably 2 or more. The alkane may be linear or branched. Examples of alcohols include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol, 2-phenoxyethanol, benzyl alcohol, and phenoxypropanol.

[0043] Polyhydric alcohols are molecules that contain two or more hydroxyl groups. Examples of polyhydric alcohols include alkanediols and polyols. Polyhydric alcohols may have a carbon-hydrogen skeleton and two or more hydroxyl groups in their molecule, and may also have an ether-bonded oxygen atom. It is preferable that they do not have any structures other than these.

[0044] Alkanediols include, for example, compounds in which an alkane is substituted with two hydroxyl groups. Examples of alkanediols include 1,2-alkanediols, which are a general term for compounds in which hydroxyl groups are substituted at the 1st and 2nd positions of an alkane, and other alkanediols other than 1,2-alkanediols. 1,2-alkanediols are preferred. The number of carbon atoms in alkanediols is preferably 2 or more, more preferably 3 to 10. Furthermore, 5 or more is preferred, and 5 to 8 is more preferred. On the other hand, 4 or fewer carbon atoms is also preferred.

[0045] Examples of 1,2-alkanediols include ethylene glycol, 1,2-propanediol (propylene glycol), 1,2-butanediol, 1,2-pentanediol (1,2PD), 1,2-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2-nonanediol, 1,2-decanediol, 3-methyl-1,2-butanediol, 3-methyl-1,2-pentanediol, 4-methyl-1,2-pentanediol, 3,4-dimethyl-1,2-pentanediol, 3-ethyl-1,2-pentanediol, 4-ethyl-1,2-pentanediol, 3-methyl-1,2-hexanediol, 4-methyl-1,2-hexanediol, and 5-methyl-1,2-hexanediol. Examples include diols, 3,4-dimethyl-1,2-hexanediol, 3,5-dimethyl-1,2-hexanediol, 4,5-dimethyl-1,2-hexanediol, 3-ethyl-1,2-hexanediol, 4-ethyl-1,2-hexanediol, and 3-ethyl-4-methyl-1,2-hexanediol.

[0046] Other examples of alkanediols include 1,3-propanediol, 1,3-butylene glycol (also known as 1,3-butanediol), 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2,4-pentanediol, 2-methyl-1,3-propanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, and 2-methyl-2-propyl-1,3-propanediol.

[0047] Examples of polyols include condensates formed by the intermolecular condensation of two or more alkanediol molecules via hydroxyl groups, and compounds having three or more hydroxyl groups.

[0048] Examples of condensates formed by the intermolecular condensation of two or more alkanediol molecules at their hydroxyl groups include dialkylene glycols such as diethylene glycol and dipropylene glycol, and trialkylene glycols such as triethylene glycol and tripropylene glycol.

[0049] Compounds having three or more hydroxyl groups are compounds with an alkane or polyether structure as their backbone and containing three or more hydroxyl groups. Examples of compounds having three or more hydroxyl groups include glycerin, trimethylolethane, trimethylolpropane, 1,2,5-hexanetriol, 1,2,6-hexanetriol, pentaerythritol, and polyoxypropylenetriol.

[0050] Organic solvents may be used individually or in combination of two or more types.

[0051] Among these, water-soluble organic solvents having a surface tension of 30 mN / m or less at 25°C in a 20% aqueous solution are preferred. When such water-soluble organic solvents are included in the maintenance fluid, the nozzle recovery performance tends to be superior. The surface tension of the 20% aqueous solution of the water-soluble organic solvent at 25°C is more preferably 28 mN / m or less, and even more preferably 26 mN / m or less.

[0052] Examples of water-soluble organic solvents whose 20% aqueous solution has a surface tension of 30 mN / m or less at 25°C include 1,2-hexanediol (25.45 mN / m) and 3-methoxy-3-methylbutanol (29.66 mN / m).

[0053] The water-soluble organic solvent having a surface tension of 30 mN / m or less in a 20% aqueous solution at 25°C is more preferably an alkanediol having 5 or more carbon atoms, and more preferably 6 or more. Alkanediols with 5 or more carbon atoms tend to have particularly excellent nozzle recovery properties. The number of carbon atoms is preferably 10 or less. Alternatively, the water-soluble organic solvent having a surface tension of 30 mN / m or less in a 20% aqueous solution at 25°C is preferably glycol ethers. The number of carbon atoms in glycol ethers is preferably 3 to 10, more preferably 4 to 8, and even more preferably 5 to 7. The number of carbon atoms in the ether portion of glycol ethers is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2. Glycol monoethers are preferred.

[0054] The content of the organic solvent is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total mass of the maintenance fluid. On the other hand, the content of the organic solvent is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, relative to the total mass of the maintenance fluid.

[0055] The content of a water-soluble organic solvent, whose 20% aqueous solution has a surface tension of 30 mN / m or less at 25°C, is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to the total mass of the maintenance fluid. On the other hand, the content of the water-soluble organic solvent is preferably 15% by mass or less, more preferably 12% by mass or less, even more preferably 10% by mass or less, and particularly preferably 8% by mass or less, based on the total mass of the maintenance fluid. In particular, if the maintenance fluid contains 3% or more by mass of a water-soluble organic solvent, whose 20% aqueous solution has a surface tension of 30 mN / m or less at 25°C, relative to the total mass of the maintenance fluid, the nozzle recovery performance tends to be superior.

[0056] 1.1.4.3 Surfactants The maintenance fluid may contain a surfactant. Any of the following surfactants can be used: nonionic surfactants, anionic surfactants, cationic surfactants, or amphoteric surfactants, and these may be used in combination. Among surfactants, acetylene glycol surfactants, silicone surfactants, and fluorine surfactants are more preferably used, and silicone surfactants are even more preferably used.

[0057] The acetylene glycol-based surfactant is not particularly limited, but for example, one or more selected from 2,4,7,9-tetramethyl-5-decine-4,7-diol and alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decine-4,7-diol, and 2,4-dimethyl-5-decine-4-ol and alkylene oxide adducts of 2,4-dimethyl-5-decine-4-ol are preferred. Commercially available acetylene glycol-based surfactants include, but are not limited to, Surfinol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, and DF110D (all are brand names, manufactured by Air Products Japan Co., Ltd.). Examples include Olphine B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP.4001, EXP.4036, EXP.4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all brand names, manufactured by Nisshin Chemical Industry Co., Ltd.), and Acetylene Nol E00, E00P, E40, E100 (all brand names, manufactured by Kawaken Fine Chemical Co., Ltd.). Acetylene glycol-based surfactants may be used individually or in combination of two or more types.

[0058] Silicone-based surfactants are not particularly limited, but examples include polysiloxane compounds and polyether-modified organosiloxanes. Commercially available silicone-based surfactants are not particularly limited, but examples include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348, BYK-349 (all product names, manufactured by Bic Chemie Japan Co., Ltd.), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017 (all product names, manufactured by Shin-Etsu Chemical Co., Ltd.), Silface SAG503A, Silface SAG014 Examples include (product names, manufactured by Nisshin Chemical Industry Co., Ltd.). Silicone-based surfactants may be used individually or in combination of two or more types.

[0059] Examples of fluorinated surfactants include, but are not limited to, perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphate esters, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkylamine oxide compounds. Examples of commercially available fluorinated surfactants include, but are not limited to, S-144, S-145 (trade names, manufactured by Asahi Glass Co., Ltd.); FC-170C, FC-430, Florard-FC4430 (trade names, manufactured by Sumitomo 3M Limited); FSO, FSO-100, FSN, FSN-100, FS-300 (trade names, manufactured by Dupont); FT-250, 251 (trade names, manufactured by Neos Co., Ltd.). Fluorinated surfactants may be used individually or in combination of two or more types.

[0060] The above-mentioned surfactants may be used individually or in combination of two or more. Furthermore, some of the exemplified surfactants that function as defoaming agents may also be used. An example of such a defoaming agent is Surfinol DF110D (trade name, manufactured by Air Products Japan Co., Ltd.).

[0061] Among these, the maintenance fluid preferably contains a surfactant whose 0.1% propylene glycol solution has a surface tension of 30-35 mN / m at 25°C. The inclusion of this surfactant tends to result in superior nozzle recovery.

[0062] Examples of surfactants with a surface tension of 30-35 mN / m at 25°C in a 0.1% propylene glycol solution include BYK-348 (34.68 mN / m) and BYK-349 (33.86 mN / m) (both trade names, manufactured by BYK-Chemie Japan Co., Ltd.).

[0063] The surfactant content is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, particularly preferably 1.5% by mass or less, and most particularly preferably 1.0% by mass or less, relative to the total mass of the maintenance fluid. The lower limit of the surfactant content is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass or more, relative to the total mass of the maintenance fluid. The content of the defoaming agent among the surfactants is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, even more preferably 1.0% by mass or less, particularly preferably 0.7% by mass or less, and most particularly preferably 0.5% by mass or less, relative to the total mass of the maintenance liquid. Furthermore, there is no particular lower limit to the content of the defoaming agent among the surfactants, but it is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and most preferably 0.1% by mass or more, relative to the total mass of the maintenance liquid.

[0064] It is also preferable to use the same amount of surfactant as described above, such that the 0.1% propylene glycol solution has a surface tension of 30-35 mN / m at 25°C.

[0065] 1.1.4.4 Neutralizing agent The maintenance fluid may contain a neutralizing agent. The neutralizing agent is not particularly limited, but examples include inorganic acids (e.g., sulfuric acid, hydrochloric acid, nitric acid, etc.), inorganic bases (e.g., lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, etc.), organic bases (triethanolamine, diethanolamine, monoethanolamine, triisopropanolamine), and organic acids (e.g., adipic acid, citric acid, succinic acid, etc.). Among these, organic salts are particularly important. The group is preferred, with triethanolamine (TEA) and triisopropanolamine being more preferred.

[0066] The neutralizing agent content is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, even more preferably 1.0% by mass or less, particularly preferably 0.7% by mass or less, and most particularly preferably 0.5% by mass or less, relative to the total mass of the maintenance fluid. The lower limit of the neutralizing agent content is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and most preferably 0.1% by mass or more, relative to the total mass of the maintenance fluid.

[0067] 1.1.4.5 Other ingredients The maintenance fluid may contain additives such as preservatives, fungicides, rust inhibitors, viscosity modifiers, solubilizers, and antioxidants, as needed. When such additives are included, the content is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and even more preferably 0.1 to 1% by mass, relative to the total mass of the maintenance fluid.

[0068] 1.2 Suction process The maintenance method according to this embodiment may include a suction step after the above-described standing step in which liquid such as ink is suctioned from the nozzles of the inkjet head. Including a suction step tends to result in better nozzle recovery.

[0069] Figure 2 shows a schematic cross-sectional view illustrating the process of drawing liquid such as ink from the nozzle of an inkjet head using a suction mechanism. The suction mechanism comprises a capping device 300, a suction tube 310, and a suction device 320.

[0070] The capping device 300 is positioned to cover the nozzle forming surface 222 of the inkjet head 2 during the suction process and receives the ink discharged from the inkjet head 2.

[0071] The suction device 320 is connected to the capping device 300 via a suction tube 310 and is a device for performing a suction process to remove ink and other materials from inside the inkjet head 2. The suction device 320 can create negative pressure inside the capping device 300 to forcibly eject any ink and other materials remaining inside the inkjet head 2.

[0072] 1.3 Wiping process The maintenance method according to this embodiment may include a wiping step after the above-described settling step, in which the nozzle surface on which the nozzles of the inkjet head are formed is wiped with an absorbent material containing a maintenance liquid. Including a wiping step tends to result in better nozzle recovery.

[0073] The wiping method is not particularly limited, but for example, wiping can be performed by pressing the absorbent member against the nozzle surface and moving the absorbent member or the nozzle surface in a direction along the nozzle surface.

[0074] The wiping direction is not particularly limited, but it is preferable to wipe in a direction along the nozzle row. This prevents the portion of the absorbent member that has come into contact with one nozzle row from coming into contact with another nozzle row and contaminating the nozzle surface.

[0075] The pressing load of the absorbent member on the nozzle-forming surface during the wiping process can be the same as the pressing load during the standing process described above.

[0076] 1.4 Applicable to The maintenance method according to this embodiment is a maintenance method for a recording device having an inkjet head with a nozzle that ejects an aqueous ink composition.

[0077] 1.4.1 Ink composition The components included in the ink composition are not particularly limited, but examples include water, colorants, fixing resins, surfactants, and organic solvents. Preferably, the ink composition is an inkjet ink composition used in an inkjet method. The components included in the ink composition will be described below.

[0078] 1.4.1.1 Water The ink composition is a water-based composition and contains water. The type and amount of water in the ink composition can be the same as that of the maintenance fluid described above.

[0079] 1.4.1.2 Colorants The ink composition may contain colorants. Examples of colorants include dyes and pigments.

[0080] Examples of pigments that can be used include inorganic pigments containing carbon black and titanium white, and organic pigments.

[0081] Inorganic pigments that can be used include carbon blacks such as CI Pigment Black 6 (Lamp Black, Vegetable Black), CI Pigment Black 7 (Furnace Black, Channel Black, Thermal Black, Acetylene Black), CI Pigment Black 8 (Charcoal Black), and CI Pigment Black 10 (Graphite), as well as iron oxide, titanium oxide, zinc oxide, silica, and the like.

[0082] Examples of carbon black include Mitsubishi Chemical Corporation's No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, and No. 2200B. Examples of Degussa's Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Pritex 35, U, V, 140U, and Special Black 6, 5, 4A, 4, and 250. Examples of Columbia Carbon's Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, and 700. Examples include Cabot's Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, and Elftex 12.

[0083] Examples of white pigments include metal compounds such as metal oxides, barium sulfate, and calcium carbonate. Examples of metal oxides include titanium dioxide, zinc oxide, silica, alumina, and magnesium oxide. In addition, particles with a hollow structure may be used as the white pigment.

[0084] Examples of organic pigments include quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ancenthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, or azo pigments. Specific examples of organic pigments are listed below.

[0085] The cyan pigments are CI Pigment Blue 1, 2, 3, 15:3, 15:4, 1 Examples include 5:34, 16, 22, 60, etc.; CI Bat Blue 4, 60, etc. Preferably, one or more mixtures selected from the group consisting of CI Pigment Blue 15:3, 15:4, and 60 can be exemplified.

[0086] Examples of magenta pigments include CI Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 168, 184, 202, and CI Pigment Violet 19. Preferably, one or more mixtures selected from the group consisting of CI Pigment Red 122, 202, and 209, and CI Pigment Violet 19 can be used. Solid solutions of the above pigments may also be used.

[0087] Examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, 185, etc. Preferably, one or more mixtures selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128, 138, 155, and 180 can be exemplified.

[0088] Examples of orange pigments include CI Pigment Orange 36 or 43, or mixtures thereof. Examples of green pigments include CI Pigment Green 7 or 36, or mixtures thereof.

[0089] Furthermore, lustrous pigments may be used, and are not particularly limited as long as they exhibit lustrous properties when attached to a medium. Examples include metal particles of one or more alloys (also called metallic pigments) selected from the group consisting of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and copper, or pearl pigments having a pearlescent luster. Typical examples of pearl pigments include titanium dioxide-coated mica, fish scale foil, and bismuth acid chloride, which are pigments that have a pearlescent or interference luster. In addition, lustrous pigments may be subjected to surface treatment to suppress their reaction with water.

[0090] The above pigments may be used individually or in combination of two or more. From the viewpoint of storage stability, such as lightfastness, weather resistance, and gas resistance, organic pigments are preferable.

[0091] The volume-average particle size (D50) of the pigment, as measured by dynamic light scattering, is 20 nm to 300 nm, more preferably 30 nm to 200 nm, and even more preferably 40 nm to 100 nm.

[0092] The volume-average particle size can be measured, for example, using a NanoTrac series particle distribution analyzer manufactured by MicroTracBel. Methods for adjusting the volume-average particle size include, for example, adjusting the degree of grinding of the pigment before dispersion, adjusting the stirring conditions during dispersion (e.g., stirring speed, stirring temperature, etc.), and adjusting by filtration using a filter after dispersion.

[0093] Furthermore, to improve the dispersibility of the pigment in the ink composition, it is preferable to surface-treat the pigment or to incorporate a dispersant.

[0094] The surface treatment of the pigment is preferably a process that directly or indirectly bonds functional groups such as carbonyl groups, carboxyl groups, aldehyde groups, hydroxyl groups, sulfone groups, ammonium groups, and salts thereof to the surface of the pigment by physical or chemical treatment. In particular, the surface treatment may involve oxidizing the pigment surface with, for example, ozone, hypochlorous acid, or fuming sulfuric acid. Alternatively, it is more preferable that the pigment particles are modified by sulfonation to alter the surface of the pigment particles.

[0095] When using a dispersant, it is preferable to use a dispersant having both a hydrophobic portion (hydrophobic group) and a hydrophilic portion (hydrophilic group) in its molecular structure. Such a dispersant has the effect of the hydrophobic portion adsorbing to the surface of the pigment particles and the hydrophilic portion orienting towards the aqueous medium side of the ink composition. This action tends to make it possible to include the pigment more stably in the ink composition as a dispersion. Such dispersants are not particularly limited, but examples include acrylic resins, styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylate copolymers and other styrene-acrylic resins, styrene-maleic acid resins, and their salts, formalin condensates of aromatic sulfonates, and one or more selected from this group can be used. Commercially available dispersants may also be used.

[0096] When dispersing pigments with a dispersant, the ratio of pigment to dispersant is preferably 10:1 to 1:10, and more preferably 4:1 to 1:3.

[0097] Alternatively, a method may be used in which the pigment particles are coated with a resin or other material to impart dispersibility. Possible methods for coating the pigment particles include acid precipitation, phase inversion emulsification, and miniemulsion polymerization.

[0098] The colorant content is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, relative to the total mass of the ink composition. When the colorant content is within the above range, the resolubility / redispersibility when forming the ink composition tends to be better. The lower limit of the colorant content is not particularly limited, but it is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more, based on the total mass of the ink composition.

[0099] 1.4.1.3 Fixing resin The ink composition may contain a fixing resin. The fixing resin has functions such as improving the adhesion and abrasion resistance of the ink components, and smoothing the surface of the recording medium or the ink coating. On the other hand, when a fixing resin is included, the ink components tend to solidify near the nozzle, causing the nozzle to clog. However, according to the maintenance method of this embodiment, even if the ink composition contains a fixing resin, excellent nozzle recovery performance tends to be obtained.

[0100] The fixing resin may be a water-soluble resin, but it is preferably in the form of resin particles. The resin particles are often handled in emulsion form, but they may also be in powder form. The fixing resin can be dispersed or dissolved in the solvent component of the ink and included in the ink.

[0101] Examples of fixing resins include urethane resins, acrylic resins (including styrene-acrylic resins), fluorene resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, and ethylene vinyl acetate resins. Among these, urethane resins, acrylic resins, polyolefin resins, and polyester resins are preferred.

[0102] Urethane resins are a general term for resins containing urethane bonds. In addition to urethane bonds, urethane resins may also include polyether-type urethane resins containing ether bonds in the main chain, polyester-type urethane resins containing ester bonds in the main chain, and polycarbonate-type urethane resins containing carbonate bonds in the main chain. Furthermore, commercially available urethane resins may be used, such as Superflex 460, 460s, 840, and E-4000. Commercially available products such as (product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020, D-4080, D-4200, D-6300, D-6455 (product name, manufactured by Dainichi Seika Kogyo Co., Ltd.), Takelac WS-6021, W-512-A-6 (product name, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), SanCure 2710 (product name, manufactured by LUBRIZOL), and Permarin UA-150 (product name, manufactured by Sanyo Chemical Industries, Ltd.) may also be used.

[0103] Acrylic resins are a general term for polymers obtained by polymerizing at least one acrylic monomer, such as (meth)acrylic acid or (meth)acrylic acid ester. Examples include resins obtained from acrylic monomers and copolymers of acrylic monomers with other monomers. For example, acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers, are examples. Examples of vinyl monomers include styrene.

[0104] Acrylic monomers such as acrylamide and acrylonitrile can also be used. For resin emulsions made from acrylic resins, commercially available products may be used, for example, selected from FK-854 (trade name, manufactured by Chuo Rika Kogyo Co., Ltd.), Movinyl 6969D, 6899D, 952B, 718A (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Nipol LX852, LX874 (trade name, manufactured by Nippon Zeon Co., Ltd.), etc.

[0105] In this specification, the acrylic resin may be a styrene-acrylic resin as described later.

[0106] Styrene-acrylic resins are copolymers obtained from styrene monomers and (meth)acrylic monomers, and examples include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, and styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers. For the styrene-acrylic resin, commercially available products may be used, such as Joncryl 62J, 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (product names, manufactured by BASF), Movinyl 966A, 975N (product names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Vinibran 2586 (manufactured by Nisshin Chemical Industry Co., Ltd.), etc.

[0107] Polyolefin resins have olefins such as ethylene, propylene, and butylene as their structural framework, and known types can be appropriately selected and used. Commercially available olefin resins can be used, for example, Arrowbase CB-1200, CD-1200 (trade names, manufactured by Unitika Ltd.).

[0108] Furthermore, the fixing resin may be supplied in emulsion form. Examples of commercially available resin emulsions include Microgel E-1002, E-5002 (product names of Nippon Paint Co., Ltd., styrene-acrylic resin emulsion), Boncoat 4001 (product name of DIC Corporation, acrylic resin emulsion), Boncoat 5454 (product name of DIC Corporation, styrene-acrylic resin emulsion), Polysol AM-710, AM-920, AM-2300, AP-4735, and AT-860. , PSASE-4210E (acrylic resin emulsion), Polysol AP-7020 (styrene-acrylic resin emulsion), Polysol SH-502 (vinyl acetate resin emulsion), Polysol AD-13, AD-2, AD-10, AD-96, AD-17, AD-70 (ethylene-vinyl acetate resin emulsion), Polysol PSASE-6010 (ethylene-vinyl acetate resin emulsion) (product name manufactured by Showa Denko Co., Ltd.), Polysol SAE1014 (product name, styrene-acrylic Acrylic resin emulsion (manufactured by Nippon Zeon Co., Ltd.), Saibinol SK-200 (product name, acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.), AE-120A (product name, manufactured by JSR Corporation, acrylic resin emulsion), AE373D (product name, manufactured by E-Tech Co., Ltd., carboxy-modified styrene-acrylic resin emulsion), Seikadine 1900W (product name, manufactured by Dainichi Seika Kogyo Co., Ltd., ethylene-vinyl acetate resin emulsion), Vinibran 2682 (acrylic resin emulsion), Vinibran 2886 (vinyl acetate-acrylic resin emulsion), Vinibran 5202 (acrylic acetate resin emulsion) (product name, manufactured by Nisshin Chemical Industry Co., Ltd.), Elitel KA-5071S, KT-8803, KT-9204, KT-870 1. KT-8904, KT-0507 (product names from Unitika Corporation, polyester resin emulsion), Hi-Tec SN-2002 (product name from Toho Chemical Co., Ltd., polyester resin emulsion), Takelac W-6020, W-635, W-6061, W-605, W-635, W-6021 (product names from Mitsui Chemicals Polyurethane Co., Ltd., urethane resin emulsion), Superflex 870, 800, 150, 420, 460, 470, 610, 700 (product names from Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion), Permarin UA-150 (manufactured by Sanyo Chemical Industries, Ltd., urethane resin emulsion), SunCure 2710 (manufactured by Nippon Lubrizol Co., Ltd., urethane resin emulsion), NeoRez R-9660, R-9637, R-940 (manufactured by Kusumoto Kasei Co., Ltd., urethane resin emulsion), Adekabon Titer HUX-380, 290K (manufactured by ADEKA Corporation, urethane resin emulsion), Movinyl 966A, Movinyl 7320 (manufactured by Nippon Synthetic Chemical Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7 You may also select and use from among 630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (all manufactured by BASF), NK Binder R-5HN (manufactured by Shin Nakamura Chemical Industry Co., Ltd.), Hydran WLS-210 (non-crosslinked polyurethane: manufactured by DIC Corporation), Joncryl 7610 (manufactured by BASF), etc.

[0109] From the viewpoint of achieving superior abrasion resistance, the content of the fixing resin in the ink composition is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.5% by mass or more, and particularly preferably 2.0% by mass or more, based on the total mass of the ink composition. Furthermore, from the viewpoint of achieving superior discharge stability, the content of the fixing resin in the ink composition is preferably 15.0% by mass or less, more preferably 10% by mass or less, even more preferably 8.0% by mass or less, and even more preferably 5.0% by mass or less, relative to the total mass of the ink composition.

[0110] 1.4.1.4 Surfactants The ink composition may contain a surfactant. The type and amount of surfactant in the ink composition can be the same as that of the maintenance fluid described above.

[0111] 1.4.1.5 Organic Solvents The ink composition may contain an organic solvent. The type and amount of organic solvent in the ink composition can be the same as that of the maintenance fluid described above.

[0112] In the ink composition, it is preferable to contain alkanediols as an organic solvent, more preferably 1,2-alkanediols, and even more preferably 1,2-alkanediols having 5 or fewer carbon atoms. These contents are preferably the same as the contents of the organic solvent in the maintenance fluid described above.

[0113] The ink composition preferably contains polyols with a standard boiling point of 250°C or higher as organic solvents in an amount of 5% by mass or less, and more preferably 3% by mass or less, relative to the total mass of the ink composition. More preferably, 1% by mass or less is preferred, particularly preferably 0.1% by mass or less is preferred, and most preferably 0% by mass (not present). When the content of polyols with a standard boiling point of 250°C or higher is within the above range, the abrasion resistance of the recording material tends to improve further. Examples of polyols with a standard boiling point of 250°C or higher include glycerin and triethylene glycol. Furthermore, it is also preferable that the content of polyhydric alcohols with a standard boiling point of 250°C or higher as organic solvents in the ink be within the above range.

[0114] 1.4.1.6 Other ingredients The ink composition may optionally contain various additives such as waxes, chelating agents, rust inhibitors, mold inhibitors, antioxidants, reduction inhibitors, and evaporation accelerators. When such additives are included, the content is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and even more preferably 0.1 to 1% by mass, relative to the total mass of the ink composition.

[0115] 1.4.2 Recording device A recording device to which the maintenance method according to this embodiment can be preferably applied will be described later.

[0116] 1.4.2.1 Recording media The recording device may dispense the above-mentioned ink composition from a nozzle and record onto a low-absorption recording medium or a non-absorption recording medium. Water-based ink compositions used when recording on such recording media may contain components such as fixing resins and tend to have poor nozzle recovery properties, but the maintenance method according to this embodiment tends to provide excellent nozzle recovery properties.

[0117] A low-absorption or non-absorption recording medium refers to a recording medium that does not absorb liquid at all or absorbs very little liquid. Quantitatively, a low-absorption or non-absorption recording medium is defined as "a recording medium that absorbs liquid at all or very little liquid from the start of contact in the Bristow method." 1 / 2Up to 10 mL / m² of water absorption capacity 2 This refers to the following recording media. The Bristow method is the most widely used method for measuring liquid absorption in a short time and is also adopted by the Japan Paper & Pulp Technology Association (JAPAN TAPPI). Details of the test method are described in standard No. 51 "Paper and cardboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper & Pulp Test Methods 2000 Edition". In contrast, absorbent recording media refer to recording media that do not fall under the categories of low-absorbent recording media or non-absorbent recording media.

[0118] Examples of low-absorption recording media include recording media with a low-absorption coating layer on their surface, known as coated paper. Examples of paper-based recording media include art paper, coated paper, matte paper, and other printing papers. Examples of plastic-based recording media include those coated with polymers on the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc., or those coated with silica, titanium, or other particles together with a binder.

[0119] Examples of non-absorbent recording media include those in which a plastic coating is applied to a substrate such as paper, those in which a plastic film is adhered to a substrate such as paper, and plastic films that do not have an absorbent layer (receiving layer). Examples of such plastics include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

[0120] 1.4.2.2 Recording Method (Ink application process) The recording performed by the recording device may include an ink application step in which the above-mentioned ink composition is ejected from the inkjet head and adhered to the recording medium.

[0121] The amount of ink composition applied is preferably 2.0 to 20 mg / inch 2More preferably 3.0 to 10 mg / inch 2 And more preferably 6.0 to 8.0 mg / inch 2 It is also preferable that the recording medium includes the region of the above adhesion amount range, and that the maximum adhesion amount range of the ink composition in recording is less than or equal to the above adhesion amount range.

[0122] (Primary drying process) The recording process performed by the recording device may include a drying step (primary drying step) in the ink application process to dry the recording medium. Including such a drying step allows the ink to dry more quickly, which tends to improve scratch resistance and image quality.

[0123] The primary drying process involves heating or blowing air onto the recording medium to quickly dry the ink. The primary drying process dries at least a portion of the solvent component of the ink that has adhered to the recording medium, to the extent that it reduces the flow of the ink. The primary drying process may be carried out so that the ink adheres to the heated recording medium, or it may be carried out early after adhesion to accelerate drying.

[0124] In the primary drying process, it is preferable that the ink droplets that have landed on the recording medium begin to dry no later than 0.5 seconds after landing. The drying unit (drying mechanism) for drying the ink on the recording medium is not particularly limited, but examples include platen heaters, hot air heaters, IR heaters, etc., which have a heating function, and blowers, etc., which do not have a heating function.

[0125] Types of drying mechanisms include conduction type, which heats the recording medium by transferring heat from a component in contact with the recording medium to the recording medium; radiation type, which heats the recording medium by radiating radiation such as IR to the recording medium; and airflow type, which blows air towards the recording medium.

[0126] The blower method (blowing process) includes methods that heat the recording medium while applying hot air, and methods that promote ink drying with room temperature air without heating. The method without heating is preferable because it suppresses the drying of ink in the inkjet head nozzles and the resulting decrease in ejection stability. It is also preferable to use the blower method in combination with either the conduction method or the radiation method. When used in combination, the blower method may also be a method without heating, which is preferable.

[0127] During the ink deposition process, the surface temperature of the recording medium facing the inkjet head is preferably 60°C or lower, more preferably 55°C or lower. Furthermore, it is preferably 50°C or lower, even more preferably 45°C or lower. Even more preferably 40°C or lower, 35°C or lower, 30°C or lower, and 27°C or lower. On the other hand, the temperature is preferably 20°C or higher, more preferably 25°C or higher, even more preferably 30°C or higher, particularly preferably 35°C or higher, and even more particularly preferably 40°C or higher. Furthermore, it is preferably 30-60°C, even more preferably 35-55°C. Even more preferably 40-50°C.

[0128] When the surface temperature of the recording medium is above the above range, drying performance is improved, and the abrasion resistance of the resulting recorded material tends to be improved. Conversely, when the temperature is below the above range, clogging recovery, ejection stability, and color development are also better, which is preferable.

[0129] Furthermore, the primary drying process may be omitted, or the primary drying process may not involve heating. In this case, the surface temperature of the recording medium on the platen should be kept below the above range. It is preferable that this is easier to do. On the other hand, when performing a primary drying process that involves heating, it is preferable that the surface temperature of the recording medium on the platen is easier to raise to above the above range.

[0130] Furthermore, when using a blower type (where the ink adhesion process includes a blower step), the wind speed near the recording medium is preferably 0.2 m / s or more, more preferably 0.5 m / s or more, even more preferably 1.0 m / s or more, particularly preferably 1.5 m / s or more, and most preferably 2.0 m / s or more. It is even more preferably 4.0 m / s or more, particularly preferably 5 m / s or more, and most preferably 7.0 m / s or more. On the other hand, a speed of 20 m / s or less is preferred, 15 m / s or less is more preferred, 13 m / s or less is even more preferred, and 12 m / s or less is particularly preferred. Furthermore, a speed of 0.5 to 10 m / s is preferred, 1 to 4 m / s is more preferred, and 2 to 3 m / s is even more preferred. The air temperature is preferably 45°C or lower, more preferably 40°C or lower, even more preferably 32°C or lower, even more preferably 30°C or lower, even more preferably 27°C or lower, and even more preferably 25°C or lower. On the other hand, it is preferably 20°C or higher, and even more preferably 23°C or lower. The wind speed and temperature are measured near the recording surface of the recording medium on the platen.

[0131] (Secondary drying process) The recording process performed by the recording device may include a heating step (secondary heating step) for heating the recording medium to which the ink composition is attached. The secondary heating step is a step to complete the recording and heat the recording material sufficiently so that it can be used. The secondary heating step is also a step to ensure that the solvent components of the ink are sufficiently dried and that the fixing resin and other components contained in the ink are heated to flatten the ink coating.

[0132] The secondary heating step is preferably started more than 0.5 seconds after the ink adheres to the recording medium. For example, it is preferable to start heating a recording area of ​​the recording medium more than 0.5 seconds after the ink has completely adhered to that area.

[0133] The surface temperature of the recording medium in the secondary heating step is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher. In the secondary heating step, heating the surface temperature of the recording medium to 60°C or higher tends to result in excellent drying properties and better moisture resistance and friction resistance. The upper limit is preferably 100°C or lower, and more preferably 90°C or lower.

[0134] Furthermore, the secondary heating mechanism can be a conduction type, a radiation type, a forced-air type, or the like.

[0135] 2. Recording device A recording device according to one embodiment of the present invention is a recording device that is maintained by the maintenance method described above, and comprises the inkjet head described above, the absorbent member described above, and the maintenance liquid described above.

[0136] According to the recording device of this embodiment, maintenance is performed by the maintenance method described above, and excellent nozzle recovery performance can be obtained.

[0137] The recording device according to this embodiment will be described below with reference to the drawings.

[0138] Figure 3 is a schematic cross-sectional view illustrating the inkjet recording device 1. Figure 4 is a perspective view showing an example of the configuration around the carriage of the inkjet recording device 1 shown in Figure 3. Figures 1 and 2 show the maintenance equipment around the inkjet head of the inkjet recording device 1 shown in Figure 3. This is a schematic cross-sectional view showing an example of the configuration related to the lance. As shown in Figures 3 and 4, the inkjet recording device 1 comprises an inkjet head 2, an absorbent member 21, an IR heater 3, a platen heater 4, a heating heater 5, a cooling fan 6, a preheater 7, a ventilation fan 8, a carriage 9, a platen 11, a carriage movement mechanism 13, a transport means 14, and a control unit CONT. The operation of the entire inkjet recording device 1 is controlled by the control unit CONT shown in Figure 4.

[0139] The inkjet head 2 is an inkjet head having nozzles for ejecting the above-mentioned ink composition, and can record onto the recording medium M by ejecting and adhering the ink composition from the nozzles of the inkjet head.

[0140] By using a mechanism having an absorbent member 21 containing a maintenance fluid 31 as shown in Figure 1, the above-mentioned settling process and wiping process can be performed on the nozzle forming surface 222 of the inkjet head 2.

[0141] Furthermore, by using a suction mechanism having a capping device 300, a suction tube 310, and a suction device 320, as shown in Figure 2, the above-mentioned suction process, which forcibly ejects ink or the like from the nozzle of the inkjet head 2, can be performed.

[0142] In this embodiment, the inkjet head 2 is a serial inkjet head that scans the recording medium M one or more times in the main scanning direction relative to the recording medium M to deposit the above-mentioned ink composition onto the recording medium M. The inkjet head 2 is mounted on a carriage 9 shown in Figure 4. The inkjet head 2 is scanned one or more times in the main scanning direction relative to the recording medium M by the operation of a carriage movement mechanism 13 that moves the carriage 9 in the media width direction of the recording medium M. The media width direction is the main scanning direction of the inkjet head 2. Scanning in the main scanning direction is also called main scanning.

[0143] Here, the main scanning direction is the direction in which the carriage 9, on which the inkjet head 2 is mounted, moves. In Figure 3, this direction intersects the sub-scanning direction, which is the transport direction of the recording medium M indicated by arrow SS. In Figure 4, the width direction of the recording medium M, i.e., the direction represented by S1-S2, is the main scanning direction MS, and the direction represented by T1→T2 is the sub-scanning direction SS. Note that in one scan, scanning is performed in the main scanning direction, i.e., in either the direction of arrow S1 or arrow S2.

[0144] The cartridge 12 that supplies ink to the inkjet head 2 includes a plurality of independent cartridges. The cartridge 12 is detachably mounted on the carriage 9 on which the inkjet head 2 is mounted. Each of the plurality of cartridges may be filled with a different type of ink, and ink is supplied from the cartridge 12 to each nozzle. In this embodiment, the example shown is that the cartridge 12 is mounted on the carriage 9, but it is not limited to this, and may be provided in a location other than the carriage 9, with ink supplied to each nozzle by a supply pipe (not shown).

[0145] Conventional known methods can be used for ejection from the inkjet head 2. In this embodiment, a method is used that ejects droplets using the vibration of a piezoelectric element, that is, an ejection method that forms ink droplets by the mechanical deformation of an electrostrictive element.

[0146] The inkjet recording device 1 is equipped with a ventilation fan 8, an IR heater 3, and a platen heater 4 for drying the ink ejected from the inkjet head 2 and adhering to the recording medium M. These ventilation fan 8, IR heater 3, and platen heater 4 are combined as appropriate. By using them together, a primary drying process can be performed. In the primary drying process, it is not always necessary to heat the recording medium M; the ventilation fan 8 may be used alone to provide airflow at room temperature.

[0147] Furthermore, by using the IR heater 3, the recording medium M can be heated radiantly by infrared radiation from the inkjet head 2 side. This makes it easier for the inkjet head 2 to be heated at the same time, but the temperature can be raised without being affected by the thickness of the recording medium M, compared to when the recording medium M is heated from the back side by a platen heater 4 or the like. In addition, various fans (e.g., ventilation fan 8) may be provided to dry the ink on the recording medium M by blowing warm air or air at the same temperature as the environment onto the recording medium M.

[0148] The platen heater 4 can heat the recording medium M via the platen 11 at a position opposite the inkjet head 2 so that the ink ejected by the inkjet head 2 can dry quickly from the moment it adheres to the recording medium M. The platen heater 4 can heat the recording medium M by conduction, thereby allowing ink to adhere to the heated recording medium M.

[0149] Furthermore, it is preferable that the surface temperature of the recording medium M, due to heating by the IR heater 3 and the platen heater 4, be within the range described in the primary drying step above.

[0150] The heating element 5 is a heater for drying and solidifying the ink attached to the recording medium M, in other words, a heater for secondary drying. The heating element 5 can be used in the secondary drying process. When the heating element 5 heats the recording medium M on which the image is recorded, moisture and other substances contained in the ink evaporate more quickly and are scattered, and an ink film is formed by the resin particles that may be contained in the ink. In this way, the ink film is firmly fixed or adhered to the recording medium M, resulting in excellent film-forming properties, and a high-quality image can be obtained in a short time.

[0151] The surface temperature of the recording medium M due to heating by the heating element 5 is preferably within the range described in the secondary drying step above. When the temperature is within the aforementioned range, high-quality images tend to be obtained in a short time.

[0152] The inkjet recording device 1 may have a cooling fan 6. After the ink recorded on the recording medium M dries, the ink on the recording medium M is cooled by the cooling fan 6, thereby forming an ink coating film with good adhesion on the recording medium M.

[0153] Furthermore, the inkjet recording device 1 may be equipped with a preheater 7 that preheats the recording medium M before ink is applied to it. In addition, the inkjet recording device 1 may be equipped with a ventilation fan 8 to allow the ink applied to the recording medium M to dry more efficiently.

[0154] Below the carriage 9 are a platen 11 that supports the recording medium M, a carriage movement mechanism 13 that moves the carriage 9 relative to the recording medium M, and a transport means 14 which is a roller that transports the recording medium M in the sub-scanning direction. The operation of the carriage movement mechanism 13 and the transport means 14 is controlled by the control unit CONT.

[0155] In other embodiments of this invention, the inkjet recording apparatus may be a line-type inkjet recording apparatus in which the inkjet head 2 is a line head. For example, in Figure 3, the inkjet head 2 is a line head having a length greater than or equal to the recording width in the width direction of the recording medium, and its position is fixed. Ink is ejected from the inkjet head 2 onto the conveyed recording medium M and adheres to the recording medium. In this case, recording is performed by a single main scan. If inkjet head 2 is a line head, the rest of the configuration should be the same as in the serial type described above.

[0156] 3. Examples The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" below refers to mass.

[0157] 3.1 Preparation of maintenance fluid Each component is placed in a mixing tank to obtain the maintenance solution for each example (ST-1 to ST-6) by mixing and stirring, and then filtering through a 5 μm membrane filter, as shown in Table 1 (Figure 5). Pure water is added so that the total mass of the composition is 100% by mass.

[0158] Further explanation is provided regarding the information in Table 1. [Surfactants] • BYK349 ​​(product name manufactured by Bic Chemie Japan, 0.1% propylene glycol solution with a surface tension of 33.86 mN / m at 25°C, silicone-based surfactant) • BYK3420 (Product name manufactured by Bic Chemie Japan, 0.1% propylene glycol solution with a surface tension of 27.19 mN / m at 25°C, silicone-based surfactant) [Antifoaming agent] • DF110D (Product name manufactured by Air Products Japan Co., Ltd.)

[0159] The surface tension of water-soluble organic solvents is measured using an automatic surface tensimeter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) by checking the surface tension when a platinum plate is wetted with a 20% by mass aqueous solution of the water-soluble organic solvent at 25°C.

[0160] 3.2 Preparation of Ink Composition Each component is placed in a mixing tank to obtain the ink compositions (BK-1, BK-2) shown in Table 2 (Figure 6). The mixture is mixed and stirred, and then filtered through a 5 μm membrane filter. Pure water is added so that the total mass of the composition is 100% by mass. The values ​​for each component are the net mass of that component.

[0161] Further explanation is provided regarding the information in Table 2. [Colorants] • Carbon black ("CAB-O-JET300", Cabot Corporation product name, 15% solids content, self-dispersing pigment) [Fixing resin] • Movinyl 6969D (product name manufactured by Nippon Synthetic Chemical Industry Co., Ltd., acrylic resin emulsion) [Surfactants] • BYK349 ​​(product name manufactured by Bic Chemie Japan, 0.1% propylene glycol solution with a surface tension of 33.86 mN / m at 25°C, silicone-based surfactant)

[0162] 3.3 Printing Conditions The records used in the evaluation test are subject to the following conditions: Printing machine: SurePress L-4733A (manufactured by Seiko Epson Corporation), modified version. Recording medium: "PET50A" (product name manufactured by Lintec Corporation, PET transparent film) Print mode: "film 8Pass#0" Surface temperature of the recording medium on the platen (printing temperature): See Table 3 (RT represents room temperature (25°C)). In the example with a drying fan, a 10 m / s, 25°C airflow is blown near the recording medium on the platen.

[0163] 3.4 Maintenance Conditions The "Method of applying maintenance fluid to the nozzle surface" (maintenance conditions) described in Table 3 is as follows: • "Absorbent Material Immersion 1" involves immersing the absorbent material ("Bemliese," a product name manufactured by Asahi Kasei Corporation, made of cellulose fiber) in the maintenance liquid shown in Table 3 at a rate of 50 mg / inch. 2 The material is applied and then left to stand in contact with the nozzle surface of the inkjet head for a predetermined period of time. • "Absorbent material immersion 2" reduces the amount of maintenance fluid adhering to 30 mg / inch 2 Except for the above, the procedure is the same as for immersion of the absorbent material 1. • "Spraying" involves spraying the maintenance fluid shown in Table 3 onto the nozzle surface of the inkjet head and leaving it there for a specified time. • "Cap immersion" involves filling the cap with the maintenance fluid shown in Table 3 and immersing the nozzle surface of the inkjet head in the maintenance fluid for a specified time. The amount of maintenance fluid should be such that the nozzle surface is completely submerged in the cap. • "Wiping the absorbent material" involves applying 50 mg / inch of the maintenance liquid shown in Table 3 to the absorbent material ("Bemliese," a product name manufactured by Asahi Kasei Corporation, made of cellulose fiber). 2 The absorbent material is attached to the nozzle surface of the inkjet head and then moved back and forth for a predetermined time while in contact with the nozzle surface.

[0164] 3.5 Evaluation Test 3.5.1 Nozzle Resilience The ink composition for each example is filled into the printing press, and printing is performed for 1 hour under the above printing conditions with the nozzles disengaged. Air bubbles are intentionally introduced into the nozzles to create a non-dispensing state (nozzle disengaged state). Then, the maintenance fluid for each example is applied to the nozzle surface under the above maintenance conditions described in Table 3, and suction cleaning is performed. Nozzle recovery performance is evaluated based on the following criteria. A rating of C or higher is considered good. The evaluation is based on the percentage of recovered nozzles. (Judgment criteria) A: The clogged nozzle recovers by more than 50% within the specified maintenance time of 1 minute. B: The clogged nozzle recovers by more than 50% within the specified maintenance time of 3 minutes. C: The clogged nozzle recovers by more than 50% within the specified maintenance time of 4 minutes. D: The clogged nozzle does not recover more than 50% within the specified maintenance time of 4 minutes.

[0165] 3.5.2 Solubility of Activating Agents The maintenance fluid for each example is sealed in a container and stored in a constant temperature bath, and its solubility is evaluated based on the following criteria. (Judgment criteria) A: It does not separate even after heating at 60°C for a week. B: Does not separate even after heating at 40°C for one week. C: Separation occurs when heated at 40°C for one week.

[0166] 3.5.3 Scratch resistance In the "nozzle recovery performance" evaluation test described above, maintenance is performed for a specified time of 4 minutes under the above maintenance conditions, and the recording is made using the recording device after maintenance. The degree of ink peeling is visually checked on the obtained printed material after rubbing it 50 times with a JSPS-type abrasion resistance tester (load 500g), and the abrasion resistance is evaluated based on the following criteria. (Judgment criteria) A: No peeling occurs. B: Peeling is less than 10% C: Peeling exceeds 10%

[0167] 3.5.4 Cleaning success rate The ink composition for each example is loaded into the printing press, and the inkjet head nozzle surface is left facing the platen for 30 minutes under the above printing conditions. Then, maintenance for each example is performed with the specified maintenance time set to 1 minute, and after maintenance, suction cleaning is performed. The cleaning success rate is evaluated based on the following criteria. A rating of C or higher is considered good. (Judgment criteria) A: No non-discharge nozzles occur after one cleaning. B: No non-discharge nozzles occur after two cleaning cycles. C: No nozzle failures occur after 3-4 cleanings. D: Nozzle failure occurred after 4 cleanings.

[0168] 3.5.5 Antifoaming properties For each example, the maintenance fluid is placed in a glass screw tube, and after stirring 20 times, the time it takes for the foam to disappear is measured. The defoaming properties are then evaluated based on the following criteria. (Judgment criteria) A: The bubbles will disappear within 12 hours. B: The bubbles will disappear within 24 hours. C: The bubbles don't disappear even after more than 24 hours.

[0169] 3.6 Evaluation Results The evaluation results are shown in Table 3. Based on the results shown in Table 3, the maintenance methods for a recording device having an inkjet head with nozzles that eject an aqueous ink composition, which include a settling step in which the nozzle surface of the inkjet head, on which the nozzles are formed, is in contact with an absorbent material containing a maintenance liquid, all of the maintenance methods according to each embodiment exhibit excellent nozzle recovery.

[0170] Furthermore, the procedure was the same as in Example 1, except that the maintenance fluid was applied to the nozzle surface and then the absorbent material was brought into contact with the nozzle surface for a predetermined time. The results of each evaluation test were the same as in Example 1.

[0171] In contrast, Reference Examples 1 and 3, which do not satisfy the above configuration, have poor nozzle recovery performance. Furthermore, Reference Example 2 cannot reduce the amount of maintenance fluid used.

[0172] The following conclusions can be drawn from the embodiments described above.

[0173] One form of maintenance method is: A method for maintaining a recording device having an inkjet head with a nozzle for ejecting an aqueous ink composition, The process includes a settling step in which the nozzle surface of the inkjet head, on which the nozzle is formed, is placed in contact with an absorbent material containing maintenance fluid and left to stand.

[0174] In one embodiment of the above maintenance method, The resting time in the resting step may be 1 minute or more.

[0175] In any embodiment of the above maintenance method, The maintenance fluid is applied to the nozzle surface and the nozzle to which the maintenance fluid is applied Alternatively, the nozzle surface may be brought into contact with the absorbent member and left to stand, or the maintenance liquid may be applied to the absorbent member, and the nozzle surface may be brought into contact with the absorbent member to which the maintenance liquid has been applied and left to stand.

[0176] In any embodiment of the above maintenance method, During the aforementioned standing process, the content of the maintenance fluid in the absorbent member is 30 mg / inch 2 That's fine too.

[0177] In any embodiment of the above maintenance method, The maintenance fluid may contain 3% by mass or more of a water-soluble organic solvent, whose 20% aqueous solution has a surface tension of 30 mN / m or less at 25°C, relative to the total mass of the maintenance fluid.

[0178] In any embodiment of the above maintenance method, The aforementioned water-soluble organic solvent may be an alkanediol having 6 or more carbon atoms.

[0179] In any embodiment of the above maintenance method, The recording device may dispense the ink composition from the nozzle and record it onto a low-absorbency recording medium or a non-absorbency recording medium.

[0180] In any embodiment of the above maintenance method, The system may include, after the standing step, a suction step in which suction is performed from the nozzle, and a wiping step in which the nozzle surface is wiped with the absorbing member.

[0181] In any embodiment of the above maintenance method, The ink composition may contain polyols with a standard boiling point of 250°C or higher as an organic solvent in an amount of 1% by mass or less relative to the total mass of the ink composition.

[0182] In any embodiment of the above maintenance method, The maintenance fluid may contain a surfactant whose 0.1% propylene glycol solution has a surface tension of 30-35 mN / m at 25°C.

[0183] In any embodiment of the above maintenance method, The aforementioned maintenance fluid may be water-based.

[0184] One embodiment of a recording device is: A recording device that is maintained by any of the above-described maintenance methods, The system comprises the inkjet head, the absorbent member, and the maintenance fluid.

[0185] In one embodiment of the above recording device, The system may have a drying mechanism that performs a primary drying step when recording data.

[0186] The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments, for example, configurations that have the same function, method and result, or configurations that have the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments. [Explanation of Symbols]

[0187] 1... Inkjet recording device, 2... Inkjet head, 3... IR heater, 4... Platen heater, 5... Heating heater, 6... Cooling fan, 7... Preheater, 8... Ventilation fan, 9... Carriage, 11... Platen, 12... Cartridge, 13... Carriage moving mechanism, 14... Conveying means, 222... Nozzle forming surface, 21... Absorbing member, 22... First roll, 23... Second roll, 24... First sprayer, 25... Second sprayer, 26... Pool, 31... Maintenance fluid, 40... Pressing member, 300... Capping device, 310... Suction tube, 320... Suction device, CONT... Control unit, MS... Main scanning direction, SS... Sub-scanning direction, M... Recording medium.

Claims

1. A method for maintaining a recording device having an inkjet head with a nozzle for ejecting an aqueous ink composition, A maintenance method comprising a settling step of placing the nozzle surface of the inkjet head, on which the nozzle is formed, in contact with an absorbent material containing maintenance fluid.

2. The maintenance method according to claim 1, wherein the resting time of the resting step is 1 minute or more.

3. A maintenance method according to claim 1 or claim 2, wherein the maintenance liquid is applied to the nozzle surface, the nozzle surface to which the maintenance liquid is applied is brought into contact with the absorbent member, and the process is left to stand, or the maintenance liquid is applied to the absorbent member, the nozzle surface is brought into contact with the absorbent member to which the maintenance liquid is applied, and the process is left to stand.

4. During the aforementioned standing process, the content of the maintenance fluid in the absorbent member is 30 mg / inch. ２ The maintenance method according to claim 1 or claim 2.

5. The maintenance method according to claim 1 or claim 2, wherein the maintenance liquid contains 3% by mass or more of a water-soluble organic solvent, whose 20% aqueous solution has a surface tension of 30 mN / m or less at 25°C, relative to the total mass of the maintenance liquid.

6. The maintenance method according to claim 5, wherein the water-soluble organic solvent is an alkanediol having 6 or more carbon atoms.

7. The maintenance method according to claim 1 or claim 2, wherein the recording device ejects the ink composition from the nozzle and records it on a low-absorbency recording medium or a non-absorbency recording medium.

8. The maintenance method according to claim 1 or claim 2, further comprising: a suction step of performing suction from the nozzle after the standing step; and a wiping step of wiping the nozzle surface with the absorbing member.

9. The maintenance method according to claim 1 or claim 2, wherein the ink composition contains 1% by mass or less of polyols with a standard boiling point of 250°C or higher as an organic solvent, relative to the total mass of the ink composition.

10. The maintenance method according to claim 1 or claim 2, wherein the maintenance liquid contains a surfactant whose surface tension at 25°C is 30 to 35 mN / m when it is a 0.1% propylene glycol solution.

11. The maintenance method according to claim 1 or claim 2, wherein the maintenance fluid is aqueous.

12. A recording device that performs maintenance by the maintenance method described in claim 1, A recording device comprising the inkjet head, the absorbent member, and the maintenance fluid.

13. The recording apparatus according to claim 12, comprising a drying mechanism that performs a primary drying step when recording.

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