JPWO2007148495A1 - Replacement liquid for print head of actinic ray curable ink jet printer and cleaning method for print head of actinic ray curable ink jet printer using the same - Google Patents

Abstract

The present invention relates to a print head replacement liquid for an actinic radiation curable ink jet printer that prevents occurrence of nozzle clogging in the print head, and a method for cleaning the print head of an actinic light curable ink jet printer using the print head replacement liquid. provide. This actinic radiation curable ink jet printer print head replacement liquid is used when filling ink into an actinic radiation curable ink jet printer print head that has not been filled with ink, or with other ink on the ink filled print head. A replacement liquid for an actinic radiation curable ink jet printer used for refilling the ink, containing at least one cyclic ester compound in an amount of 10% by weight to 40% by weight, and contained in a newly filled ink It is characterized by containing 10 mass% or more and 40 mass% or less of the at least 1 sort (s) of polymerizable compound.

Description

  The present invention relates to a print head replacement liquid for an actinic radiation curable ink jet printer that does not cause nozzle clogging, and a method for cleaning the print head of an actinic light curable ink jet printer using the replacement liquid.

  In recent years, inkjet recording systems have been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters from the viewpoint of being able to create images easily and inexpensively. In particular, ink jet recording devices that emit and control fine dots, ink with improved color reproduction gamut, durability, and emission suitability, ink absorbency, coloring material color development, surface gloss, etc. are dramatically improved. It is also possible to obtain image quality comparable to silver halide photography using special paper. The image quality improvement of today's ink jet recording system is achieved only when all of these ink jet recording apparatuses, inks, and dedicated papers are available.

  However, in an inkjet system that requires dedicated paper, there is a problem that the usable recording medium is limited and the economical efficiency of the recording medium. Therefore, many attempts have been made to record an inkjet image on a transfer medium different from the dedicated paper by the inkjet method. Specifically, a phase change inkjet method using a solid wax ink at room temperature, a solvent-based inkjet method using an ink mainly composed of a fast-drying organic solvent, or an ultraviolet curing that is crosslinked by ultraviolet (UV) light after recording. Type ink jet method.

  In particular, the ultraviolet curable ink jet method has been attracting attention in recent years in that it can record on a recording medium having relatively low odor, quick drying and no ink absorption compared to the solvent type ink jet method. An ultraviolet curable inkjet ink is disclosed (for example, see Patent Documents 1 and 2).

  On the other hand, inkjet printers that use UV-curable inkjet ink eject inkjet ink from the small-diameter ejection openings (nozzles) that form the print head. Color materials contained in the ink-jet ink, for example, pigments aggregate in the head, and the discharge ports are blocked by the pigment aggregates. In particular, in an ultraviolet curable ink jet ink, the ink jet ink is cured by being irradiated with ultraviolet rays in the vicinity of the discharge port, whereby the discharge port is blocked, or a gel-like substance is generated and the discharge port is blocked. Have problems.

  As a technique for preventing the nozzles from being clogged as described above, for example, a method is disclosed in which the ejection port is covered with a cap when the inkjet printer is not performing an image recording operation (for example, a patent). References 3-6.) As another method, there is disclosed a technique for wiping off ink adhering to the vicinity of an ejection port when an ink jet printer is performing an image recording operation or attempting to end an image recording operation (for example, Patent Document 4). ~ 7).

However, when each of the proposed technologies is applied to an ultraviolet curable ink jet system, the effect is not yet sufficient, especially when ink jet ink is first filled into a print head, or ink jet ink has already been filled. When refilling the printhead with other types of inkjet ink, it is very difficult to eliminate nozzle clogging. Furthermore, a technique using a cleaning liquid containing a polymerizable compound contained in a newly filled inkjet ink as a main component (for example, containing 50% by mass or more) is also disclosed (see Patent Document 8). There is a problem that gelation is likely to occur due to the above, and there is a possibility that nozzle clogging may be caused in reverse, and the development of an improved technique is desired.
JP-A-6-200204 (Claims) JP 2000-504778 A (Claims) JP-A-57-117964 (Claims) JP-A-57-80064 (Claims) JP 59-111856 A (Claims) JP-A-8-1953 (Claims) Japanese Patent Publication No. 62-9030 (Claims) JP 2006-35467 A (Claims)

  The present invention has been made in view of the above-mentioned problems, and its purpose is to use a print head replacement liquid for an actinic radiation curable ink jet printer that prevents the occurrence of nozzle clogging in the print head, and the print head replacement liquid. Another object of the present invention is to provide a method for cleaning a print head of an actinic ray curable ink jet printer.

  The above object of the present invention is achieved by the following configurations.

  1. Actinic ray curable inkjet printer print head used when filling ink into an actinic ray curable inkjet printer print head that is not filled with ink, or when refilling a print head filled with ink with another ink A replacement liquid for use in which at least one cyclic ester compound is contained in an amount of 10 mass% or more and 40 mass% or less, and at least one polymerizable compound contained in a newly filled ink is contained in an amount of 10 mass% or more. 40% by mass or less of a print head replacement liquid for an actinic radiation curable ink jet printer.

  2. 2. The replacement liquid for a print head of an actinic ray curable ink jet printer as described in 1 above, comprising at least one glycol ether compound in an amount of 50% by mass to 80% by mass.

  3. The replacement liquid for a print head of an actinic ray curable ink jet printer as described in 1 or 2 above, wherein the viscosity at 25 ° C. is lower than the viscosity at 25 ° C. of the newly filled ink.

  The surface tension at 4.25 ° C. is 20 mN / m or more and 40 mN / m or less, the replacement liquid for a print head of an actinic radiation curable ink jet printer according to any one of 1 to 3 above.

  5). The cyclic ester compound is propylene carbonate, β-propiolactone, β-butyrolactone, α-methyl-β-butyrolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone, γ-caprolactone and γ. The replacement liquid for a print head of an actinic radiation curable ink jet printer according to any one of 1 to 4, wherein the replacement liquid is at least one selected from heptanolactone.

  6). 6. The replacement liquid for a print head of an actinic radiation curable ink jet printer according to any one of 1 to 5, wherein the polymerizable compound is a compound having an oxetane ring.

  7. 7. The replacement liquid for a print head of an actinic radiation curable ink jet printer according to any one of 2 to 6, wherein the glycol ether compound has a boiling point of 150 ° C. or higher.

  8). The dye or pigment is contained as a coloring material in an amount of 0.02% by mass or more and 1.50% by mass or less for the print head of an actinic ray curable ink jet printer according to any one of 1 to 7 above. Replacement liquid.

  9. A method for cleaning a print head of an actinic radiation curable ink jet printer, wherein the print head replacement liquid according to any one of 1 to 8 is filled or circulated in the print head. A method for cleaning a print head of an actinic radiation curable ink jet printer, comprising a step of feeding the liquid and a step of discharging a replacement liquid for the print head of the actinic radiation curable ink jet printer.

  According to the present invention, there is provided a print head replacement liquid for an actinic radiation curable ink jet printer that prevents the occurrence of nozzle clogging in the print head, and a method for cleaning an actinic light curable ink jet printer print head using the print head replacement liquid. Could be provided.

It is the schematic which shows an example of the washing | cleaning method of the print head using the substitution liquid of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Print head 2 Nozzle surface 3 Rubber cap 4 Replacement liquid inflow part 5A-5D Liquid supply piping 6 Liquid supply pump 7 Replacement liquid 8 Replacement liquid storage container 9 Filter A Circulation liquid supply process B Discharge process

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventor has found that when the ink is filled into the print head of the actinic ray curable ink jet printer that is not filled with ink, A replacement liquid for a print head of an actinic radiation curable ink jet printer used for refilling ink, comprising at least one cyclic ester compound of 10% by weight to 40% by weight, and newly filled ink Occurrence of nozzle clogging in a print head is caused by a replacement solution for a print head of an actinic ray curable ink jet printer characterized by containing at least one of the contained polymerizable compounds in an amount of 10% by mass to 40% by mass. Preventing actinic ray curable inkjet printer print head installation Found to be able to realize a liquid, a completed the invention.

  Usually, in a print head in an ink jet printer in a shipping state, a solvent used for confirming ejection properties and cleaning the head before shipping each print head remains. In such a state, when a new ink is filled and fed to the print head, there is a problem that aggregation of coloring materials such as dyes or pigments occurs due to contact between the remaining solvent and the ink. In the case of the type inkjet ink, there are problems such as generation of a gel substance due to the polymerizable compound contained and precipitation of the initiator.

  As a result of intensive studies on the above problems, the present inventor has found that a replacement liquid for an actinic ray curable inkjet printer satisfying the following requirements (hereinafter simply referred to as a replacement liquid) before filling the print head of the inkjet printer with ink. It was also found that it is necessary to fill or circulate the print head in advance. The requirement is that 10% by mass or more and 40% by mass or less of at least one cyclic ester compound, and 10% by mass or more of at least one polymerizable compound contained in the ink to be newly filled. It is to contain below mass%. Furthermore, it has been found that the inclusion of at least one glycol ether compound in an amount of 50% by mass or more and 80% by mass or less is preferable in terms of suppressing the generation of a gel substance.

  Details of the present invention will be described below.

[Substitution liquid]
The replacement liquid of the present invention is used when filling a print head of an actinic radiation curable ink jet printer that is not filled with ink, or when refilling a print head that is filled with ink with another ink. Yes, at least one cyclic ester compound is contained in an amount of 10% by mass or more and 40% by mass or less, and at least one of the polymerizable compounds contained in the newly filled ink is 10% by mass or more and 40% by mass or less. It is characterized by containing.

(Cyclic ester compound)
The cyclic ester compound used in the present invention will be described. The replacement liquid of the present invention contains at least one cyclic ester compound in an amount of 10% by mass to 40% by mass in order to suppress precipitation of a photoinitiator in the ink when the ink is filled in the head. Is one of the features. If the content of the cyclic ester compound according to the present invention is 10% by mass or more, the effect of preventing the occurrence of nozzle clogging can be exhibited, and if it is 40% by mass or less, the dye or pigment in the ink The occurrence of aggregation can be prevented.

  The cyclic ester compound according to the present invention is not particularly limited, but propylene carbonate, β-propiolactone, β-butyrolactone, α-methyl-β-butyrolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, From the standpoint of more achieving the object effects of the present invention, it is preferably at least one selected from ε-caprolactone, γ-caprolactone and γ-heptanolactone.

(Photopolymerizable compound)
Next, the photopolymerizable compound used in the present invention will be described.

  In the replacement liquid of the present invention, when the ink is filled into the print head, at least one contained in the newly filled ink in order to suppress aggregation of the coloring material contained in the ink, for example, the dye or pigment dispersion. One of the characteristics is that it contains 10% by mass or more and 40% by mass or less of the seed polymerizable compound. If the content of the photopolymerizable compound according to the present invention is 10% by mass or more, the effect of preventing the occurrence of nozzle clogging can be exhibited, and when used at 40% by mass or less, the polymerizable compound is gelled. The generation of substances and the accompanying nozzle clogging can be prevented.

  Examples of the polymerizable compound that is preferably used in the substitution liquid for a print head that uses a cationic photopolymerization ink jet ink include, for example, OXT221 and OXT101 manufactured by Toa Gosei Co., Ltd., Celoxide 3000, Celoxide 2000, and AOE manufactured by Daicel Chemical Industries, Ltd. -X24, AOE-X68 etc. are mentioned.

  In addition, as a polymerizable compound that is preferably used in a substitution liquid for a print head using a photo radical polymerization type ink-jet ink, any known monofunctional acrylate is preferably used, and examples thereof include isoamyl acrylate, stearyl acrylate, and lauryl. Examples include acrylate, octyl acrylate, cetyl acrylate, decyl acrylate, isomyristyl acrylate, isostearyl acrylate, ethoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, isobornyl acrylate, and lactone-modified flexible acrylate.

  The polymerizable compound used in the substitution liquid of the present invention is a compound having an oxetane ring, which suppresses aggregation of the dye and pigment dispersion in the newly filled ink and causes a problem of generation of a gel substance. It is more preferable because it is difficult.

(Glycol ether compound)
The substitution liquid of the present invention preferably contains at least one glycol ether compound in an amount of 50% by mass to 80% by mass with the cyclic ester compound and the polymerizable compound from the viewpoint of further reducing the generation of a gel substance. .

  Although there is no restriction | limiting in particular as a glycol ether compound which concerns on this invention, A boiling point is a glycol ether compound with a 150 degreeC or more from a viewpoint of suppressing volatilization and scattering (VOC regulation) of the compound at the time of use.

  As the glycol ether compound according to the present invention, any commercially available one can be used. For example, diethylene glycol monomethyl ether (boiling point 194 ° C., viscosity 4.1 mPa · s), triethylene glycol monomethyl ether (boiling point 249 ° C., viscosity 8.3 mPa · s), diethylene glycol monobutyl ether (boiling point 230 ° C., viscosity 6.6 mPa · s). ), Dipropylene glycol monomethyl ether (boiling point 188 ° C., viscosity 4.1 mPa · s), diethylene glycol dimethyl ether (boiling point 162 ° C., viscosity 1.1 mPa · s), triethylene glycol dimethyl ether (boiling point 216 ° C., viscosity 2.2 mPa · s). ), Tetraethylene glycol dimethyl ether (boiling point 275 ° C., viscosity 3.8 mPa · s), diethylene glycol diethyl ether (boiling point 189 ° C., viscosity 1.4 mPa · s), diethylene glycol dibutyl ether (Boiling point 256 ° C., viscosity 2.4 mPa · s), diethylene glycol ethyl methyl ether (boiling point 176 ° C., viscosity 1.2 mPa · s), diethylene glycol isopropyl methyl ether (boiling point 179 ° C., viscosity 1.3 mPa · s), diethylene glycol butyl Methyl ether (boiling point 212 ° C., viscosity 1.6 mPa · s), triethylene glycol butyl methyl ether (boiling point 261 ° C., viscosity 2.9 mPa · s), dipropylene glycol dimethyl ether (boiling point 171 ° C., viscosity 1.2 mPa · s) , Tripropylene glycol dimethyl ether (boiling point: 215 ° C., viscosity: 2.25 mPa · s), etc., which are sold as “High Solve” series by Toho Chemical Industry Co., Ltd.

(Liquid properties of the replacement liquid)
In the replacement liquid of the present invention, the viscosity at 25 ° C. is preferably lower than the viscosity at 25 ° C. of the ink to be newly filled from the viewpoint of improving the replacement efficiency.

  Further, the substitution liquid of the present invention preferably has a surface tension at 25 ° C. of 20 mN / m or more and 40 mN / m or less. By adjusting the surface tension within this range, it is possible to fill the replacement liquid over the details in the print head. Any known surfactant can be used as means for adjusting the surface tension, but it is preferable to contain a nonionic surfactant. For example, polyoxyethylene-polyoxypropylene condensate, polyoxyethylene lauryl ether, secondary alcohol ethoxylate, primary alcohol ethoxylate, nonylphenol ethoxylate, octylphenol ethoxylate, oleyl alcohol ethoxylate, lauryl alcohol ethoxylate, Hydroxyl-containing unsaturated monomers such as polyethylene glycol, polyoxyethylene glycol oleate, sorbitan stearyl ester, sorbitan oleyl ester, polyoxyethylene sorbitan oleyl ester, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, polyethylene glycol monomethacrylate An acrylic resin having a copolymerized body can be used. Furthermore, alcohols such as isopropyl alcohol, n-butyl alcohol, propylene glycol monomethyl ether, propylene glycol monobutyl ether, or glycol ethers are exemplified. Other examples include fluorine-based surfactants having a perfluoroalkyl group in the molecule, such as perfluoroalkylethylene oxide adducts, perfluoroalkylamine oxides, perfluoroalkyl-containing oligomers, and the like. Specifically, for example, “SURFLON S-141”, “Surflon S-145”, “Surflon S-381”, “Surflon S-383”, “Surflon S-393”, “Surflon SC” -101 "," Surflon SC-105 "," Surflon KH-40 "," Surflon SA-100 "(manufactured by Seimi Chemical Co., Ltd.)," Megafac F-171 "," Megafac F-172 " , “Megafuck F-173”, “Megafuck F-177”, “Megafu "F-178A", "Megafuck F-178K", "Megafuck F-179", "Megafuck F-183", "Megafuck F-184", "Megafuck F-815", "Megafuck" F-470 "," Megafuck F-471 "(manufactured by Dainippon Ink & Chemicals, Inc.) and the like.

  In the present invention, the nonionic surfactant is preferably used in the range of 20 to 50,000 ppm, more preferably 50 to 20,000 ppm in the ink. If the content of the nonionic surfactant is 20 ppm or more, it can be adjusted to a desired surface tension, and if the content is 50,000 ppm or less, excessive foaming can be suppressed, resulting from foaming. The occurrence of missing nozzles can be prevented.

  In the substitution liquid of the present invention, it is preferable to contain various known dyes or pigments in the range of 0.02 to 1.50% by mass as a coloring material for the purpose of improving handleability (visibility). If the dye or pigment content is 0.02% by mass or more, a sufficient visual effect can be obtained, and if it is 1.50% by mass or less, aggregation caused by the dye or pigment is prevented. can do.

The dye used in the substitution liquid of the present invention is preferably an oil-based dye. Specific examples include, for example, Valentine Yellow 4120, Valentine Yellow 3150, Valentine Yellow 3108, Valentine Yellow 2310N, Valentine 1 Yellow, manufactured by Orient Chemical Industry Co., Ltd. Red 3320, Variast Red 3304, Variast Red 1306, VariFast Blue 2610, VariFast Blue 2606, VariFast Blue 1603, Oil Yellow GG-S, Oil Yellow 3Gow, Oil 29G
Yellow 107, Oil Yellow 105, Oil Scallet 308, Oil Red RR, Oil Red OG, Oil Red 5B, Oil Pink 312, Oil Blue BOS, Oil Blue 613, Oil Blue 2N, Oil Black Bil, Oil Black Bil Oil Black 5970, Oil Black 5906, Oil Black 5905,
Kayset Yellow SF-G, Kayase Yellow K-CL, Kayase Yellow GN, Kayase Yellow AG, Kayase Yellow 2G, Kayset Red SF-G, Kayset Red A-BLK , KaysetMagenta 312, Kayase Blue K-FL, etc.
FS Yellow 1015, FS Magenta 1404, FS Cyan 1522, FS Blue 1504, C.I. I. Solvent Yellow 88, Solvent Yellow 83, Solvent Yellow 82, Solvent Yellow 79, Solvent Yellow 56, Solvent Yellow 29, Solvent Yellow 19, Solvent Yellow 16, Solvent Yellow 14, Solvent Yellow 04, Solvent Yellow 04, Solvent Yellow 04, Solvent Yellow 03 , C.I. I. Solvent Red 84: 1, C.I. I. Solvent Red 84, C.I. I. Solvent Red 218, C.I. I. Solvent Red 132, C.I. I. Solvent Red 73, C.I. I. Solvent Red 72, C.I. I. Solvent Red 51, C.I. I. Solvent Red 43, C.I. I. Solvent Red 27, C.I. I. Solvent Red 24, Solvent Red 18, Solvent Red 01, Solvent Blue 70, Solvent Blue 67, Solvent Blue 44, Solvent Blue 40, Solvent Blue 35, Solvent Blue 11, SolBlu 01, Sol02 Blue 01, SolBlu 11 I. Solvent Black 70, C.I. I. Solvent Black 34, C.I. I. Solvent Black 29, C.I. I. Solvent Black 27, C.I. I. Solvent Black 22, C.I. I. Solvent Black 7, C.I. I. Solvent Black 3, C.I. I. Solvent Violet 3, C.I. I. Solvent Green 3 and C.I. I. Solvent Green 7 etc. are mentioned.

As the pigment, any known pigment can be used, for example,
C. I. Pigment Yellow; 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 109, 114, 120, 128, 129, 138 , 150, 151, 154, 180, 185,
C. I. Pigment Red; 5, 7, 12, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 1, 63: 1, 101, 112, 122, 123, 144 146, 168, 184, 185, 202,
C. I. Pigment Violet; 19, 23,
C. I. Pigment Blue; 1, 2, 3, 15: 1, 15: 2, 15: 3, 15: 4, 18, 22, 27, 29, 60,
C. I. Pigment Green; 7, 36,
C. I. Pigment White; 6, 18, 21,
C. I. Pigment Black 7
Etc.

  Further, when a pigment is used as a coloring material, the dispersion of the pigment includes, for example, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, a paint shaker, and the like. Can be used. Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid if necessary. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. The dispersion medium is preferably performed using a polymerizable compound.

[Washing method using substitution liquid of the present invention]
Hereinafter, a print head cleaning method using the replacement liquid of the present invention and a circulation liquid feeding method thereof will be described with reference to the drawings as appropriate. The drawings show only one aspect of the cleaning method of the present invention, and the aspects of the present invention are not limited to the configurations described in the drawings.

  FIG. 1 is a schematic view showing an example of a print head cleaning method using the replacement liquid of the present invention.

  In FIG. 1, a rubber cap 3 is in close contact with the nozzle surface 2 of the print head 1 and is connected to a liquid feed pump 6 (for example, a tubing pump) via a substitution liquid feed pipe 5A. At this time, the print head 1 preferably includes a mechanism capable of heating the ink flow path with a surface heater.

  The liquid feed pump 6 is connected to the replacement liquid storage container 8 via a liquid feed pipe 5B. In the replacement liquid storage container 8, a certain volume of the replacement liquid 7 is stored. In the replacement liquid 7, a liquid supply pipe 5 </ b> C is disposed, and the replacement liquid 7 is placed upstream of the liquid supply pipe C. A filter 9 (for example, a disk filter having a filtration diameter of 3 μm) for removing foreign matters such as dust contained in the replacement liquid 7 is provided before feeding to the print head 1, and the replacement filtered by the filter 9 The liquid 7 is supplied from a replacement liquid inflow portion 4 provided in the print head 1 through a liquid supply pipe 5D.

  As described above, as the cleaning method of the present invention, the replacement liquid 7 stored in the replacement liquid storage container 8 is supplied to the print head 1 through the filter 9 and is filled or circulated for cleaning the inside of the print head 1. It is mainly comprised from the liquid process A and the discharge process B which discharges the substitution liquid used for washing | cleaning to the substitution liquid storage container 8 from the nozzle part 2 using a liquid feeding pump.

  As a specific cleaning procedure of the print head and a replacement liquid circulation method, in the replacement liquid circulation path shown in FIG. 1, the liquid supply pump 6 is operated to pressurize the liquid supply pipe 5 </ b> B, and the replacement liquid storage container 8. After removing the foreign substance etc. with the filter 9 through the liquid supply pipe 5C, the replacement liquid 7 stored in the flow is introduced into the print head 1 heated by the surface heater or the like from the replacement liquid inflow portion 4, After the solvent and ink remaining in the print head 1 are dissolved in the replacement liquid 7, the replacement liquid 7 is sent out of the print head 1 through the nozzle portion 2. By performing this operation for a certain period of time, the inside of the print head 1 is completely replaced and washed with the replacement liquid, and aggregation or the like when the second ink is filled in the print head can be effectively prevented. .

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<Preparation of ink>
[Preparation of pigment dispersion a]
The following two compounds were put in a stainless beaker and dissolved by heating and stirring for 1 hour while heating on a hot plate at 65 ° C.

PB822 (dispersant manufactured by Ajinomoto Fine Techno Co., Ltd.) 9 parts OXT-221 (Oxetane compound manufactured by Toagosei Co., Ltd.) 71 parts After cooling the above solution to room temperature, Pigment Red 122 (manufactured by Dainichi Seika Co., Ltd., CFR-) 321) was added, and 200 g of zirconia beads having a diameter of 0.5 mm were placed in a glass bottle, sealed tightly, dispersed for 6 hours in a paint shaker, zirconia beads were removed, and pigment dispersion a was prepared.

[Preparation of pigment dispersion b]
The following two compounds were put in a stainless beaker and dissolved by heating and stirring for 1 hour while heating on a 65 ° C. hot plate.

PB821 (dispersant manufactured by Ajinomoto Fine Techno Co., Ltd.) 9 parts Tetraethylene glycol diacrylate 71 parts After cooling the above solution to room temperature, 20 parts of Pigment Yellow 150 (manufactured by LANXESS, E4GN-GT CH20015) was added as a pigment. Then, 200 g of zirconia beads having a diameter of 0.5 mm were placed in a glass bottle and sealed, and after a dispersion treatment for 6 hours with a paint shaker, the zirconia beads were removed to prepare a pigment dispersion b.

[Preparation of ink A]
The following additives were sequentially mixed and stirred, and then filtered through a 3 μm depth filter MACWA0303 manufactured by Pall to prepare ink A. The viscosity of this ink A at 25 ° C. was 25 mPa · s. The viscosity was measured using a rheometer MCR300 (manufactured by Physica) under the conditions of 25 ° C. and Shear Rate = 1000 (1 / s).

Pigment: Pigment dispersion a 12.5%
Photopolymerizable compound (alicyclic epoxy compound): Celoxide 2021P (manufactured by Daicel Chemical Industries) 25.0%
Photopolymerizable compound (oxetane compound): OX-221 (supra) 40.0%
Photopolymerizable compound (oxetane compound): OX-213 (manufactured by Toagosei Co., Ltd.) 15.0%
Surfactant: KF-351 (manufactured by Shin-Etsu Chemical) 0.4%
Basic compound: Tributylamine 0.1%
Anthracene derivative: DBA (manufactured by Kawasaki Kasei Co., Ltd.) 1.0%
Photoacid generator (propylene carbonate 50% solution): UVI6992 (manufactured by Dow Chemical Co.) 6.0%
[Preparation of ink B]
The following additives were sequentially mixed and stirred, and then filtered through a 3 μm depth filter MACWA0303 manufactured by Pall to prepare ink B. The viscosity of this ink B at 25 ° C. was 20 mPa · s. The viscosity was measured using a rheometer MCR300 (manufactured by Physica) under the conditions of 25 ° C. and Shear Rate = 1000 (1 / s).

Pigment: Pigment dispersion b 17.5%
Photopolymerizable compound: Lauryl acrylate (monofunctional) 15.0%
Photopolymerizable compound: Tetraethylene glycol diacrylate (bifunctional) 42.5%
Photopolymerizable compound: trimethylolpropane triacrylate (trifunctional) 20.0%
Photoinitiator: Irgacure 184 (Ciba Specialty Chemicals) 2.5%
Photoinitiator: Irgacure 907 (manufactured by Ciba Specialty Chemicals) 2.5%
<< Preparation of substitution liquid >>
Substitution solutions were prepared using the additives described in Table 1, and filtration was performed with a 3 μm depth filter MACWA0303 manufactured by Paul Co. to obtain substitution solutions 1 to 8.

  In addition, the detail of each additive described with an abbreviation in Table 1 is as follows.

<Polymerizable compound contained in ink>
OXT-213: Oxetane compound (manufactured by Toagosei Co., Ltd.)
OXT-221: Oxetane compound (manufactured by Toagosei Co., Ltd.)
S2021P: Celoxide 2021P (manufactured by Daicel Chemical Industries)
LA: Lauryl acrylate (NK ester LA, Shin-Nakamura Chemical Co., Ltd.)
<Cyclic ester compound>
* 1: Propylene carbonate (reagent)
* 2: γ-Butyrolactone (reagent)
* 3: γ-Caprolactone (reagent)
<Glycol ether compound>
DEGDBE: Diethylene glycol dibutyl ether (Hisolv BDB, manufactured by Toho Chemical Co., Ltd.)
ML: Methyl Laurate (Excelpearl ML85 Kao)
TEGDME: Triethylene glycol dimethyl ether (Hisolv MTM, manufactured by Toho Chemical Co., Ltd.)
<Others>
Dye 1: Oil Blue 613 (manufactured by Orient Chemical Industries)
X-22: Surfactant X-22-4272 (manufactured by Shin-Etsu Chemical Co., Ltd.)
PG: Propylene glycol (non-reactive compound)

[Measurement of liquid properties of replacement liquid]
According to the following method, the viscosity and surface tension of each substitution liquid were measured, and the obtained results are shown in Table 2.

(Measurement of viscosity)
The viscosity (mPa · s) of each replacement solution was measured using a rheometer MCR300 (manufactured by Physica) under the conditions of 25 ° C. and Shear Rate = 1000 (1 / s).

(Measurement of surface tension)
The surface tension (mN / m) at 25 ° C. of each substitution solution was measured by a platinum plate method using a surface tension meter (A3 type) manufactured by Kyowa Interface Chemical Co., Ltd.

<< Evaluation of replacement liquid >>
Using the print head cleaning apparatus constituted by the circulation path shown in FIG. 1, the ejection stability was evaluated using each of the prepared replacement liquids and inks.

  In the print head cleaning apparatus shown in FIG. 1, as the print head 1, a piezo-type ink jet recording head (256 nozzles) with a solvent remaining in the interior corresponding to 5% of the total internal volume is used. Each replacement solution was circulated for 5 minutes at 20 ml / min using a tubing pump.

  Next, each ink is filled in the print head 1, and with the print head 1 heated to 50 ° C., 6 gradations are expressed by continuously discharging 5 drops of ink droplets 4 pl per drive frequency of 4 kHz. Under the possible conditions, the driving voltage was adjusted so that the droplet velocity was 6 m / s, and the ink was discharged continuously for 30 minutes.

  In addition, in said evaluation, about substitution liquids 1-5, ink A was used as an ink and this was made into evaluation conditions 2-6. Note that the cleaning condition with the replacement liquid was not performed, and the level in which the ink A was directly filled was set as the evaluation condition 1.

  Moreover, in said evaluation, about the substitution liquids 6-8, the ink B was used and this was made into evaluation conditions 8-10. In addition, the washing | cleaning process by substitution liquid was not performed but the level filled with the ink B directly was made into the evaluation conditions 7.

  According to the above method, after continuous discharge for 30 minutes, the discharge state of 256 nozzles was visually observed, and discharge stability was evaluated according to the following criteria.

○: No nozzle clogging occurs even after 30 minutes of continuous ejection. △: No nozzle clogging is observed after 30 minutes of continuous ejection, but some ink nozzles are bent. In practically acceptable range ×: After 30 minutes of continuous discharge, nozzle clogging occurs at several locations or more, which is a practical problem. ××: Ink aggregation occurs during ink filling, resulting in poor discharge from the initial stage. Table 3 shows the results obtained as described above.

  As is clear from the results shown in Table 3, the evaluation conditions of the present invention in which the print head was cleaned using the replacement liquid having the configuration defined in the present invention were the following: It can be seen that, even after continuous ejection over a long period of time, stable ejection properties can be obtained without causing defective emission due to the occurrence of aggregation or the like.

Example 2
<< Preparation of substitution liquid >>
In the preparation of the replacement liquid 4 described in Example 1, the addition amount of the polymerizable compound (OXT-221) contained in the ink, the types and addition amounts of the cyclic ester compound (* 3: γ-caprolactone) and the glycol ether compound Were made in the same manner as described in Table 4 to prepare substitution solutions 9-18. The details of each additive described in abbreviations in Table 4 are the same as those described in Example 1.

<< Evaluation of replacement liquid >>
For the prepared replacement liquids 9 to 18, the ejection stability was evaluated in the same manner as in the evaluation condition 5 described in Example 1, and the obtained results are shown in Table 5.

  As is clear from the results shown in Table 5, the cyclic ester compound is contained in an amount of 10% by mass to 40% by mass, and the polymerizable compound contained in the ink is contained in an amount of 10% by mass to 40% by mass. It can be seen that the replacement liquid can provide a stable ejection property without causing an ejection failure due to the occurrence of aggregation or the like even after continuous ejection over a long period of time after filling with ink. Further, it can be seen that the ejection stability is good when the glycol ether compound is contained in an amount of 50% by mass to 80% by mass.

Example 3
In the preparation of the substitution liquid 9 described in Example 2, a non-reactive compound (PG) was added, and the viscosity at 25 ° C. was 4 mPa · s, 8 mPa · s, 14 mPa · s, 18 mPa · s, 22 mPa · s, As a result of preparing a replacement liquid of 27 mPa · s and 32 mPa · s and evaluating the ejection stability in the same manner as in the evaluation condition 5 described in Example 1, the ink viscosity at 25 ° C. (25 mN / m) or less was obtained. It was confirmed that the replacement liquid obtained had good ejection stability.

Example 4
In the preparation of the substitution liquid 9 described in Example 2, the surface tension at 25 ° C. was adjusted to 16 mN / m, 20 mN / m, 25 mN / m, and 33 mN / m by appropriately adjusting the addition amount of the surfactant X-22. , 40 mN / m, 43 mN / m, and 50 mN / m substitution liquids were prepared, and the ejection stability was evaluated in the same manner as in the evaluation condition 5 described in Example 1. As a result, the surface tension at 25 ° C. It was confirmed that the replacement liquid having a viscosity of not less than / m and not more than 40 mN / m has good ejection stability.

Example 5
In the preparation of the substitution liquid 3 described in Example 1, as a cyclic ester compound, * 1 (propylene carbonate) was changed to β-propiolactone, β-butyrolactone, α-methyl-β-butyrolactone, γ-butyrolactone, γ, respectively. Each substitution solution was prepared in the same manner except that it was changed to -valerolactone, δ-valerolactone, ε-caprolactone, γ-caprolactone, and γ-heptanolactone, and the same as Evaluation condition 4 described in Example 1 was performed. As a result of evaluating the ejection stability, it was confirmed that the same effects as those in the evaluation condition 4 described in Example 1 were obtained.

Claims (9)

  Actinic ray curable inkjet printer print head used when filling ink into an actinic ray curable inkjet printer print head that is not filled with ink, or when refilling a print head filled with ink with another ink A replacement liquid for use in which at least one cyclic ester compound is contained in an amount of 10 mass% or more and 40 mass% or less, and at least one polymerizable compound contained in a newly filled ink is contained in an amount of 10 mass% or more. 40% by mass or less of a print head replacement liquid for an actinic radiation curable ink jet printer.   The substitution liquid for a print head of an actinic radiation curable ink jet printer according to claim 1, comprising at least one glycol ether compound in an amount of 50% by mass to 80% by mass.   The replacement liquid for a print head of an actinic radiation curable ink jet printer according to claim 1 or 2, wherein a viscosity at 25 ° C is lower than a viscosity at 25 ° C of the newly filled ink.   The surface tension at 4.25 ° C is 20 mN / m or more and 40 mN / m or less, wherein the actinic ray curable ink jet printer according to any one of claims 1 to 3 is used. Replacement fluid for print heads.   The cyclic ester compound is propylene carbonate, β-propiolactone, β-butyrolactone, α-methyl-β-butyrolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone, γ-caprolactone and γ. The replacement liquid for a print head of an actinic radiation curable ink jet printer according to any one of claims 1 to 4, wherein the replacement liquid is at least one selected from -heptanolactone.   The replacement liquid for a print head of an actinic ray curable inkjet printer according to any one of claims 1 to 5, wherein the polymerizable compound is a compound having an oxetane ring.   The replacement liquid for a print head of an actinic radiation curable ink jet printer according to any one of claims 2 to 6, wherein the glycol ether compound has a boiling point of 150 ° C or higher.   The actinic ray curable type according to any one of claims 1 to 7, wherein a dye or a pigment is contained as a coloring material in an amount of 0.02% by mass or more and 1.50% by mass or less. Replacement liquid for print heads of inkjet printers.   A method for cleaning a print head of an actinic radiation curable ink jet printer, wherein the print head replacement liquid for an actinic radiation curable ink jet printer according to any one of claims 1 to 8 A method for cleaning a print head of an actinic radiation curable ink jet printer, comprising: a step of filling or circulating liquid into the head; and a step of discharging a replacement liquid for the print head of the actinic radiation curable ink jet printer. .