JP2021155518A - Water-based inkjet ink composition, ink set, and inkjet recording device - Google Patents

Abstract

To provide a water-based inkjet ink composition that can suppress the occurrence of permanent nozzle failure that never recovers.SOLUTION: A water-based inkjet ink composition according to the present invention contains a pigment, 1- (2-hydroxyalkyl)-2-pyrrolidone, trimethylglycine, and an organic amine, and in which, setting the contained amount of pigment in the water-based inkjet ink composition as MA (mass%), the contained amount of 1-(2-hydroxyalkyl)-2-pyrrolidone as MB (mass%), and the contained amount of the trimethylglycine as MC (mass%), the relationship of MB≤MA≤MC is satisfied.SELECTED DRAWING: None

Description

The present invention relates to water-based inkjet ink compositions, ink sets, and inkjet recording devices.

In recent years, an inkjet recording method using a pigment ink containing a pigment as a coloring material has become widespread. When the pigment ink is ejected to the recording medium, the pigment is placed on the surface of the recording medium and does not penetrate into the inside, so that a clear image can be recorded.

For example, Patent Document 1 discloses an ink jet recording ink containing water, a pigment, a penetrant, and trimethylglycine. Further, the patent document describes that the purpose of adding trimethylglycine to the ink is to improve the storage stability of the ink and prevent bleeding to the receiving paper.

Japanese Unexamined Patent Publication No. 2014-70126

However, with the ink described in Patent Document 1, it has been difficult to prevent the generation of solidified products derived from pigments due to dry solidification. When this solidified substance was generated in the vicinity of the nozzle, it could not be redispersed even if the subsequent ink arrived, and permanent nozzle omission that never recovered could occur.

One aspect of the water-based inkjet ink composition according to the present invention is
Containing a pigment, a 1- (2-hydroxyalkyl) -2-pyrrolidone, and trimethyl glycine, and an organic amine, a water-based ink-jet ink composition, the content of the pigment M _{A (wt%),} the 1- (2-hydroxyalkyl) -2-pyrrolidone content of _{M B} (wt%), the content of the trimethyl glycine is taken as _{M C (wt%), M B ≦ M a} ≦ M C Satisfy the relationship.

One aspect of the ink set according to the present invention is
The first ink and the second ink having a color different from that of the first ink are included.
The first ink and the second ink each contain a pigment, 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and an organic amine, respectively.
Wherein each of the first ink and the second ink, _{M A} (wt%) the content of the pigment, the content of the 1- (2-hydroxyalkyl) -2-pyrrolidone _{M B} (wt%) , the content of the trimethyl glycine is taken as M _{C (wt%),} each of said first ink and said second ink satisfy the relationship of _{M B ≦ M a ≦ M C} .

One aspect of the inkjet recording apparatus according to the present invention is
Two or more inks sealed with the same head cap contain pigments, 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and organic amines, respectively.
Wherein each of the 2 or more ink, _{M A} (wt%) the content of the pigment, the content of the 1- (2-hydroxyalkyl) -2-pyrrolidone _{M B} (wt%), the trimethyl glycine the content of when and _{M C} (wt%), each of said two or more inks satisfy the relationship of _{M B ≦ M a ≦ M C} .

The side sectional view which shows typically the structure of the inkjet recording apparatus which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described. The embodiments described below describe examples of the present invention. The present invention is not limited to the following embodiments, and includes various modifications implemented without changing the gist of the present invention. It should be noted that not all of the configurations described below are essential configurations of the present invention.

1. 1. Water-based inkjet ink composition The water-based inkjet ink composition according to the embodiment of the present invention (hereinafter, also simply referred to as “ink composition”) includes a pigment, 1- (2-hydroxyalkyl) -2-pyrrolidone, and the like. It contains trimethylglycine and an organic amine. Hereinafter, each component contained in the water-based inkjet ink composition according to the present embodiment will be described.

1.1. Pigment The ink composition according to this embodiment contains a pigment as a coloring material. The pigment can be used without particular limitation as long as it is usually used for an inkjet water-based pigment ink.

Examples of the pigment include azo pigments (for example, azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.) and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines). Organic pigments such as pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments), nitro pigments, nitroso pigments, aniline blacks; carbon blacks (eg, furnace blacks, thermal lamp blacks, acetylene blacks, channel blacks, etc.), metal oxidation Inorganic pigments such as substances, metal sulfides and metal chlorides; extender pigments such as silica, calcium carbonate and talc can be used.

Specific examples of the above pigments include C.I. I. Pigment Yellow 64, 74, 93, 109, 110, 128, 138, 139, 150, 151, 154, 155, 180, 185; C.I. I. Pigment Red 122, 202, 209; C.I. I. Pigment Violet 19; C.I. I. Pigment Blue 15: 3, 15: 4, 60; C.I. I. Pigment Green 7 (phthalocyanine green), 10 (green gold), 36, 37; C.I. I. Pigment Brown 3, 5, 25, 26; C.I. I. Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 34, 36, 38, 64, 71 and the like.

Among these pigments, phthalocyanine pigments are preferable, and C.I. I. Pigment Blue 15: 3 and C.I. I. More preferably, it is at least one of Pigment Blue 15: 4. Since the ink composition containing the phthalocyanine pigment can reduce the content of the pigment in each color ink, it is relatively difficult to dry and solidify, and nozzle omission is unlikely to occur. However, once the ink composition containing the phthalocyanine pigment is solidified, it forms a strong solidified product, so that the ink composition does not redisperse even when the subsequent ink arrives. Therefore, if a solidified product is formed in the vicinity of the nozzle by the ink composition containing the phthalocyanine pigment, there is a problem that there is a high probability that permanent nozzle omission that never recovers will occur among the inks of each color. On the other hand, according to the ink composition according to the present embodiment, the water dispersibility of the pigment is significantly improved by adding 1- (2-hydroxyalkyl) -2-pyrrolidone having a pigment content or less. Can be done. Further, by adding trimethylglycine having a pigment content or more, trimethylglycine easily enters between the pigments, preventing the pigments from aggregating with each other, and even if the pigments agglomerate to form a solidified product, the trimethylglycine is solidified. Can be solved and redistributed. Therefore, even if the phthalocyanine pigment is used, the formation of a strong solidified product is reduced, and even if the solidified product is formed, the redispersibility is good, and it is possible to prevent the occurrence of permanent nozzle omission that never recovers. It became so.

The pigment can be obtained as a pigment dispersion obtained by dispersing in water with a dispersant, or by dispersing a self-dispersing surface-treated pigment in which a hydrophilic group is introduced on the surface of pigment particles by utilizing a chemical reaction. Alternatively, it may be added to the ink composition as a pigment dispersion obtained by dispersing a pigment coated with a polymer in water.

The pigment and the dispersant constituting the pigment dispersion liquid may be used individually by 1 type, or may be used in combination of 2 or more types.

The content of the pigment (solid content) is preferably 3.0% by mass or more, more preferably 4.0% by mass or more, based on the total amount (100% by mass) of the ink composition. The content of the pigment (solid content) is preferably 8.0% by mass or less, more preferably 7.0% by mass or less, and particularly preferably 7.0% by mass or less, based on the total amount (100% by mass) of the ink composition. It is 6.0% by mass or less. When the content of the pigment (solid content) is within the above range, a clear image can be formed on various types of recording media, and the generation of solidified material due to dry solidification of the ink composition can be reduced. can.

1.2.1- (2-Hydroxyalkyl) -2-pyrrolidone The ink composition according to this embodiment contains 1- (2-hydroxyalkyl) -2-pyrrolidone. Conventionally, as the wetting agent of the ink composition, 2-pyrrolidone is often used instead of 1- (2-hydroxyalkyl) -2-pyrrolidone. However, it has been found that the water dispersibility of the pigment can be significantly improved by adding 1- (2-hydroxyalkyl) -2-pyrrolidone having a pigment content or less to the ink composition. As a result, the formation of a strong solidified product derived from the pigment is reduced, and even if the solidified product is formed, the redispersibility is good, and it is possible to prevent the occurrence of permanent nozzle omission that never recovers. became.

Specific examples of 1- (2-hydroxyalkyl) -2-pyrrolidone include 1- (2-hydroxymethyl) -2-pyrrolidone, 1- (2-hydroxyethyl) -2-pyrrolidone, and 1- (2-hydroxy). Propyl) -2-pyrrolidone and the like can be mentioned. Among these, at least one of 1- (2-hydroxyethyl) -2-pyrrolidone and 1- (2-hydroxypropyl) -2-pyrrolidone is preferable, and 1- (2-hydroxyethyl) -2-pyrrolidone is more preferable. preferable.

The content of 1- (2-hydroxyalkyl) -2-pyrrolidone is preferably 1.0% by mass or more, more preferably 1.5% by mass, based on the total amount (100% by mass) of the ink composition. The above is particularly preferable, and it is 2.0% by mass or more. The content of 1- (2-hydroxyalkyl) -2-pyrrolidone is preferably 5.0% by mass or less, more preferably 4.5% by mass, based on the total amount (100% by mass) of the ink composition. It is less than or equal to, and particularly preferably 4.0% by mass or less. When the content of 1- (2-hydroxyalkyl) -2-pyrrolidone is within the above range, the water dispersibility of the pigment is improved, and it is possible to easily reduce the firm hardening of the pigment.

1.3. Trimethylglycine The ink composition according to this embodiment contains trimethylglycine. Since trimethylglycine is very soluble in water, it can be added in large amounts to the ink composition. By adding trimethylglycine having a pigment content or more to the ink composition, trimethylglycine easily enters between the pigments, and aggregation of the pigments can be prevented. Further, even if the pigments aggregate to form a solidified product, trimethylglycine can dissolve the solidified material and redisperse it, so that permanent nozzle omission that never recovers can be prevented. became.

The content of trimethylglycine is preferably 5.0% by mass or more, more preferably 5.5% by mass or more, and particularly preferably 6.0, based on the total amount (100% by mass) of the ink composition. It is mass% or more. The content of trimethylglycine is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and particularly preferably 13.0% by mass, based on the total amount (100% by mass) of the ink composition. It is less than mass%. When the content of trimethylglycine is within the above range, the water dispersibility of the pigment is improved, and it is possible to easily reduce the formation of a solidified pigment.

1.4. Organic Amine The ink composition according to this embodiment contains an organic amine. The organic amine has an effect of suppressing the occurrence of nozzle omission. In addition, the organic amine has a function as a weakly alkaline pH adjuster. Further, since the long-term stability of the ink composition becomes excellent by making the organic amine amphipathic, the alkanolamine is preferable among the above organic amines. Further, since clogging can be prevented by using an alkanolamine having a high boiling point, trialkanolamine is more preferable, and at least one of tripropanolamine and triethanolamine is particularly preferable.

The organic amine may be used alone or in combination of two or more.

The content of the organic amine is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, based on the total amount (100% by mass) of the ink composition. The content of the organic amine is preferably 2.0% by mass or less, and more preferably 1.0% by mass or less, based on the total amount (100% by mass) of the ink composition. When the content of the organic amine is within the above range, the pH of the ink composition can be in an appropriate range.

1.5. The ink composition according to the ratio relationship embodiment of each component, M _{A (wt%)} content of the pigment, M _{B (mass} content of the 1- (2-hydroxyalkyl) -2-pyrrolidone %), the content of the trimethyl glycine is taken as _{M C} (mass%) satisfy the relation _{M B ≦ M a ≦ M C} . By satisfying such a quantitative ratio relationship, the ink composition according to the present embodiment can significantly improve the water dispersibility of the pigment and reduce the aggregation of the pigments to form a solidified product. can. Further, even if a solidified product derived from a pigment is formed, it can be redispersed to prevent the occurrence of permanent nozzle omission that never recovers. That is, by cleaning the nozzles, the discharge of all the nozzles can be restored.

The ink composition according to the present embodiment, the content of the organic amine is taken as M _{D (wt%),} preferably satisfy the relation of M _D ≦ M _B. When the ink composition according to the present embodiment satisfies such a quantity ratio relationship, the pH of the ink composition can be adjusted to be weakly alkaline, which is excellent in long-term stability and more effective in causing nozzle omission. In some cases, it can be suppressed.

All of 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and organic amine are nitrogen-containing compounds and have a high affinity for water. When the pigment is a nitrogen-containing compound such as a phthalocyanine pigment, these four nitrogen-containing compounds are considered to have a very high affinity. Therefore, it is considered that the dispersibility between the above four nitrogen-containing compounds and water is improved, only the phthalocyanine pigment is not firmly solidified, and the redispersibility is also improved.

1.6. Other Components The ink composition according to the present embodiment may contain additives other than the above components. Examples of such additives are shown below.

<Water>
The ink composition according to this embodiment contains water as a main solvent. As the water, it is preferable to use pure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, distilled water, or ultrapure water. In particular, it is preferable to use water that has been sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide, because it prevents the growth of mold and bacteria and enables long-term storage of the ink composition.

<Wetting agent>
The ink composition according to the present embodiment preferably contains a water-soluble organic solvent having a wetting effect for the purpose of preventing clogging in the vicinity of the nozzle of the inkjet head.

Examples of the wetting agent include glycerin, 1,2,6-hexanetriol, trimethylolpropane, pentamethylene glycol, trimethylene glycol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and pentaethylene glycol. Polyethylene glycol, dipropylene glycol, tripropylene glycol, isobutylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4 with a number average molecular weight of 2,000 or less. -Polyhydric alcohols such as pentandiol, mesoerythritol, pentaerythritol, and glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol (sorbit), maltose, cellobiose, lactose, sucrose, trehalose, and So-called solid wetting agents such as sugars such as malttriol, sugar alcohols, hyaluronic acids, and ureas, alkyl alcohols having 1 to 4 carbon atoms such as ethanol, methanol, butanol, propanol, and isopropanol, and 2- Examples thereof include pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, formamide, acetamide, dimethylsulfoxide, sorbitan, acetyline, diacetin, triacetin, sulfolane and the like.

The wetting agent may be used alone or in combination of two or more.

The content of the wetting agent is preferably 2.0% by mass or more and 20.0% by mass or less, and more preferably 5.0% by mass or more and 15.0% by mass, based on the total amount (100% by mass) of the ink composition. It is mass% or less. When the content of the wetting agent is within the above range, an appropriate physical property value (viscosity, etc.) of the ink composition can be ensured, and the quality and reliability of the recording can be ensured.

<Penetrating agent>
The ink composition according to the present embodiment preferably contains a penetrant for the purpose of promoting the penetration of the aqueous solvent into the recording medium. By quickly permeating the inside of the recording medium with the aqueous solvent, it is possible to obtain a recorded material with less blurring of the image.

As such a penetrant, at least one of a polyhydric alcohol alkyl ether (also referred to as glycol ethers) and a 1,2-alkyldiol is preferably used. Examples of the alkyl ether of the polyhydric alcohol include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol mono. Isopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-tert-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl Ether, propylene glycol monoethyl ether, propylene glycol mono-tert-butyl ether, propylene glycol monopropyl ether, propylene glycol monoisopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene Glycol monoisopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether and the like can be mentioned. Examples of 1,2-alkyldiol include 1,2-pentanediol and 1,2-hexanediol. In addition to these, direct amounts of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol and the like Examples thereof include chain hydrocarbon diols.

The penetrant may be used alone or in combination of two or more.

The content of the penetrant is preferably 1.0% by mass or more and 20.0% by mass or less, and more preferably 2.0% by mass or more and 15.0% by mass, based on the total amount (100% by mass) of the ink composition. It is mass% or less. When the content of the penetrant is within the above range, the permeability of the ink composition into the recording medium can be improved, and blurring can be prevented from occurring in the image recorded by using the ink composition. Moreover, the viscosity of the ink composition can be prevented from becoming too high.

<Surfactant>
The ink composition according to the present embodiment may contain a surfactant for the purpose of adjusting the surface tension and wettability of the ink composition and improving the ejection stability.

The surfactant is not particularly limited, but is preferably a nonionic surfactant, and more preferably at least one of an acetylene glycol-based surfactant and a silicone-based surfactant.

Examples of the acetylene glycol-based surfactant include 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, DF110D (all product names, manufactured by Air Products Japan Co., Ltd.), Orfin 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 product names above, manufactured by Nisshin Kagaku Kogyo Co., Ltd.), acetylenol E00, E00P, E40, E100 (all product names above, all product names, Kawaken Fine Chemical Co., Ltd.).

Examples of the silicone-based surfactant include polysiloxane-based compounds and polyether-modified organosiloxanes. The commercially available silicone-based surfactant is not particularly limited, but specifically, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK. -348, BYK-349 (trade name, manufactured by Big 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 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), Silface 503A, Sylface 014 (trade name, manufactured by Nissin Chemical Industry Co., Ltd.) and the like can be mentioned.

The surfactant may be used alone or in combination of two or more.

The content of the surfactant is preferably 0.1% by mass or more and 2.0% by mass or less, and more preferably 0.2% by mass or more, with respect to the total amount (100% by mass) of the ink composition. 2% by mass. When the content of the surfactant is within the above range, the discharge stability may be further improved.

2. Ink set The ink set according to the embodiment of the present invention includes a first ink and a second ink having a color different from that of the first ink, and the first ink and the second ink are pigments, respectively. When a 1- (2-hydroxyalkyl) -2-pyrrolidone, and trimethyl glycine, and an organic amine, containing, for each of the first ink and the second ink, the content of the pigment M _a (wt%), _{M B} (wt%) the content of the 1- (2-hydroxyalkyl) -2-pyrrolidone, the content of the trimethyl glycine is taken as _{M C} (mass%), the first each of the ink and the second ink satisfy the relationship of _{M B ≦ M a ≦ M C} .

That is, the ink set according to the present embodiment includes two or more kinds of the above-mentioned water-based inkjet ink compositions, and the colors of the water-based inkjet ink compositions are different from each other.

When the second ink does not contain 1- (2-hydroxyalkyl) -2-pyrrolidone and / or trimethylglycine, the nozzle surface wiping operation or the first ink and the second ink are mixed in the head cap. Occasionally, it is presumed that dry solidification is likely to proceed. On the other hand, since the ink set according to the present embodiment includes two or more of the above-mentioned water-based inkjet ink compositions, the water dispersibility of the pigments is significantly improved, and the pigments agglomerate to form a solidified product. It can be reduced. Further, even if a solidified product derived from a pigment is formed, it can be redispersed to prevent the occurrence of nozzle omission that never recovers. That is, by cleaning the nozzles, the discharge of all the nozzles can be restored.

In the present invention, "different colors" means that the hue angle ∠H ° differs by 20 ° or more. The hue angle ∠H ° is ∠H ° = tan ^-1 (b ^* / a ^* ) + 180 (when a ^* <0) or ∠H ° = tan ^-1 (b ^* / a ^* ) + 360 (a). ^* > 0). a ^* and b ^* represent the perceptual chromaticity index defined in the CIELAB color space.

In the ink set according to the present embodiment, the first ink is preferably a cyan ink composition for water-based inkjet. The pigment contained in the first ink is preferably a phthalocyanine pigment, and C.I. I. Pigment Blue 15: 3 and C.I. I. More preferably, it is at least one of Pigment Blue 15: 4.

In the ink set according to the present embodiment, the second ink may be one type alone or two or more types. The second ink is not particularly limited, but is preferably at least one of a water-based inkjet yellow ink composition, a water-based inkjet magenta ink composition, and a water-based inkjet black ink composition.

3. 3. Inkjet recording device In the inkjet recording device according to the embodiment of the present invention, two or more inks sealed with the same head cap are pigment, 1- (2-hydroxyalkyl) -2-pyrrolidone, respectively. containing trimethyl glycine, and an organic amine, wherein the respective 2 or more ink, the content of the pigment M _{a (wt%),} containing the 1- (2-hydroxyalkyl) -2-pyrrolidone the amount of _{M B} (wt%), the content of the trimethylglycine when the _{M C} (wt%), each of said two or more inks satisfy the relationship of _{M B ≦ M a ≦ M C} .

Hereinafter, an example of the configuration of the inkjet recording apparatus (hereinafter, also simply referred to as “recording apparatus”) according to the present embodiment will be described with reference to FIG. In the XYZ coordinate system shown in FIG. 1, the X direction indicates the length direction of the recording medium, the Y direction indicates the width direction of the recording medium in the transport path in the recording device, and the Z direction indicates the height direction of the device.

As an example, the recording device 10 is a line-type inkjet printer capable of high-speed and high-density printing. The recording device 10 includes a feeding unit 12 for storing a recording medium P such as paper, a transport unit 14, a belt transport unit 16, a recording unit 18, and an Fd (face-down) discharge unit 20 as a “delivery unit”. The Fd (face-down) mounting portion 22 as the "mounting portion", the reversing path portion 24 as the "reversing transport mechanism", the Fu (face-up) discharging portion 26, and the Fu (face-up) mounting. It is provided with a part 28.

The feeding unit 12 is arranged at the lower part of the recording device 10 in the recording device 10. The feeding unit 12 includes a feeding tray 30 that stores the recording medium P, and a feeding roller 32 that is stored in the feeding tray 30 and sends the recording medium P to the transport path 11.

The recording medium P stored in the feed tray 30 is fed to the transport unit 14 along the transport path 11 by the feed roller 32. The transport unit 14 includes a transport drive roller 34 and a transport driven roller 36. The transport drive roller 34 is rotationally driven by a drive source (not shown). In the transport unit 14, the recording medium P is sandwiched (nipped) between the transport drive roller 34 and the transport driven roller 36 and transported to the belt transport unit 16 located on the downstream side of the transport path 11.

The belt transport unit 16 is rotatably attached to the first roller 38 located on the upstream side, the second roller 40 located on the downstream side, the first roller 38, and the second roller 40 in the transport path 11. An endless belt 42 and a support 44 that supports the upper section 42a of the endless belt 42 between the first roller 38 and the second roller 40 are provided.

The endless belt 42 is driven by a first roller 38 or a second roller 40 driven by a drive source (not shown) so as to move from the + X direction to the −X direction in the upper section 42a. Therefore, the recording medium P transported from the transport unit 14 is further transported to the downstream side of the transport path 11 in the belt transport unit 16.

The recording unit 18 includes a line-type inkjet head 48 and a head holder 46 that holds the inkjet head 48. The recording unit 18 may be of a serial type in which an inkjet head is provided on a carriage that reciprocates in the Y-axis direction. The inkjet head 48 is arranged so as to face the upper section 42a of the endless belt 42 supported by the support 44. When the recording medium P is conveyed in the upper section 42a of the endless belt 42, the inkjet head 48 ejects ink toward the recording medium P and executes recording. The recording medium P is transported to the downstream side of the transport path 11 by the belt transport unit 16 while recording. The bottom surface of the inkjet head 48 is sealed with a head cap (not shown) in order to prevent the ink from drying in the standby state.

The "line-type inkjet head" is a head provided so that a nozzle region formed in a direction intersecting the transport direction of the recording medium P can cover the entire intersection direction of the recording medium P. Alternatively, it is a head used in a recording device in which one of the recording media P is fixed and the other is moved to form an image. It should be noted that the region of the nozzles in the intersecting directions of the line head may not be able to cover the entire intersecting directions of all the recording media P supported by the recording device.

Further, a first branch portion 50 is provided on the downstream side of the transport path 11 of the belt transport portion 16. The first branch section 50 reverses the transport path 11 for transporting the recording medium P to the Fd discharge unit 20 or the Fu discharge unit 26 and the recording surface of the recording medium P, and transports the recording medium P to the recording unit 18 again. It is configured to be switchable to the reversing path 52 of the reversing path unit 24. The recording surface is inverted by the first branching unit 50 in the transfer process in the reversing path 52, and is again conveyed to the recording unit 18 so that the surface opposite to the first recording surface faces the inkjet head 48.

A second branch portion 54 is further provided on the downstream side of the first branch portion 50 along the transport path 11. The second branch portion 54 is configured to be able to switch the transport direction of the recording medium P so as to transport the recording medium P toward the Fd discharge unit 20 or the recording medium P toward the Fu discharge unit 26. There is.

The recording medium P conveyed toward the Fd discharge unit 20 in the second branch portion 54 is discharged from the Fd discharge unit 20 and placed on the Fd mounting unit 22. At this time, the recording surface of the recording medium P is placed so as to face the Fd mounting portion 22. Further, the recording medium P conveyed toward the Fu discharge unit 26 at the second branch portion 54 is discharged from the Fu discharge unit 26 and placed on the Fu mounting unit 28. At this time, the recording surface of the recording medium P is placed so as to face the side opposite to the Fu mounting portion 28.

Nozzle surface wiping operation when at least one of the two or more inks sealed in the same head cap does not contain 1- (2-hydroxyalkyl) -2-pyrrolidone and / or trimethylglycine. It is presumed that when the first ink and the second ink are mixed in the head cap, the drying and solidification is likely to proceed. On the other hand, in the inkjet recording apparatus according to the present embodiment, since the two or more inks sealed with the same head cap are the above-mentioned water-based inkjet ink compositions, when the nozzle surface of the head is wiped. Even if there is color mixing in the head cap during cleaning, permanent nozzle omission does not occur.

4. Examples Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples. Hereinafter, "%" is based on mass unless otherwise specified.

4.1. Preparation of water-based inkjet ink composition Each component was mixed at the content shown in Table 1 below, stirred at room temperature for 2 hours, and then filtered using a membrane filter having a pore size of 5 μm to obtain each ink composition. .. The unit of the content of the ink composition shown in Table 1 below is mass%.

4.2. Evaluation method 4.2.1. Evaluation of Number of Nozzles Missing The ink composition obtained above was placed in an ink cartridge of a printer PX-M860F manufactured by Seiko Epson, and printing was performed. As a condition for nozzle omission, the power is removed during printing, and the printer is left in each environment at 40 ° C for 1 day, 40 ° C for 7 days, and 40 ° C for 14 days with the head removed from the cap. Cleaning was performed once, and the number of missing nozzles in each environment was counted. Furthermore, after removing the power during printing and leaving the printer in each environment of 40 ° C for 1 day, 40 ° C for 7 days, and 40 ° C for 14 days with the head removed from the cap, cleaning was performed 20 times. This was done, and the number of missing nozzles in each environment was counted. In this evaluation of the number of nozzles missing, if there is no permanent nozzle missing after cleaning 20 times, it can be judged to be good.

4.3. Evaluation Results Table 1 below shows the composition of each water-based inkjet ink composition used in Examples and Comparative Examples, and the evaluation results.

The explanation is supplemented for each component shown in Table 1 above.
<Pigment>
-Carbon black-cyan pigment (P.B. 15: 3): C.I. I. Pigment Blue 15: 3, Copper Phthalocyanine Blue, Stable (β)
Cyan pigment (P.B. 15: 4): C.I. I. Pigment Blue 15: 4, Copper Phthalocyanine Blue, Stable (β)
-Magenta pigment (PR122): C.I. I. Pigment Red 122, Quinacridone Red <Wetting Agent>
・ Glycerin ・ 2-Pyrrolidone <Penetrating agent>
-Triethylene glycol monobutyl ether <1- (2-hydroxyalkyl) -2-pyrrolidone>
1- (2-Hydroxyethyl) -2-pyrrolidone ・ 1- (2-Hydroxypropyl) -2-pyrrolidone <organic amine>
-Triethanolamine: manufactured by Tokyo Chemical Industry Co., Ltd. <Surfactant>
-Orphin E1010: Product name manufactured by Air Products & Chemicals, acetylene glycol

From the above evaluation results, in Examples 1 to 7, it was possible to recover the generated nozzle omission by performing cleaning 20 times, and it was possible to prevent the occurrence of permanent nozzle omission. From the evaluation results of Examples 1 to 7, it can be seen that when a cyan pigment is used as the pigment, nozzle omission is more likely to occur as compared with the case where other pigments are used. The reason is P.M. B. 15: 3 and P.M. B. It is presumed that 15: 4 is a β-type crystal having high stability, and once it is dried and solidified to form a solidified product, it is difficult to redisperse.

On the other hand, in Comparative Examples 1 to 6 which did not satisfy the quantitative ratio relationship of the specific components, nozzle omission was more likely to occur than in Examples, and permanent nozzle omission was observed.

The following contents are derived from the above-described embodiment.

One aspect of the water-based inkjet ink composition is
A water-based inkjet ink composition containing a pigment, 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and an organic amine.
The aqueous inkjet ink composition, the content of _{M A} of the pigment (mass%), the 1- (2-hydroxyalkyl) content of 2-pyrrolidone _{M B} (wt%), of the trimethyl glycine the content is taken as _{M C} (mass%) satisfy the relation _{M B ≦ M a ≦ M C} .

In one aspect of the water-based inkjet ink composition,
The pigment may be a phthalocyanine pigment.

In any aspect of the water-based inkjet ink composition.
The pigment is C.I. I. Pigment Blue 15: 3 and C.I. I. It may be at least one of Pigment Blue 15: 4.

In any aspect of the water-based inkjet ink composition.
Content M _A of the pigment, may be 8 wt% or less 3% by mass or more.

In any aspect of the water-based inkjet ink composition.
Content _{M B} of the 1- (2-hydroxyalkyl) -2-pyrrolidone, it may be 5 mass% 1 mass% or more.

In any aspect of the water-based inkjet ink composition.
Content M _C of the trimethyl glycine, may be 5 mass% or more.

In any aspect of the water-based inkjet ink composition.
The organic amine may be at least one of triethanolamine and tripropanolamine.

In any aspect of the water-based inkjet ink composition.
The content of the organic amine of the aqueous inkjet ink composition is taken as M _{D (wt%)} may satisfy a relationship M _D ≦ M _B.

One aspect of the ink set is
The first ink and the second ink having a color different from that of the first ink are included.
The first ink and the second ink each contain a pigment, 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and an organic amine, respectively.
Wherein each of the first ink and the second ink, _{M A} (wt%) the content of the pigment, the content of the 1- (2-hydroxyalkyl) -2-pyrrolidone _{M B} (wt%) , the content of the trimethyl glycine is taken as M _{C (wt%),} each of said first ink and said second ink satisfy the relationship of _{M B ≦ M a ≦ M C} .

One aspect of the inkjet recording device is
Two or more inks sealed with the same cap contain pigments, 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and organic amines, respectively.
Wherein each of the 2 or more ink, _{M A} (wt%) the content of the pigment, the content of the 1- (2-hydroxyalkyl) -2-pyrrolidone _{M B} (wt%), the trimethyl glycine the content of when and _{M C} (wt%), each of said two or more inks satisfy the relationship of _{M B ≦ M a ≦ M C} .

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the present invention includes a configuration substantially the same as the configuration described in the embodiment, for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect. The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. The present invention also includes a configuration that exhibits the same effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

10 ... Recording device, 12 ... Feeding section, 14 ... Transport section, 16 ... Belt transport section, 18 ... Recording section, 20 ... Fd discharge section, 22 ... Fd mounting section, 24 ... Reverse path section, 26 ... Fu discharge Part, 28 ... Fu mounting part, 30 ... Feed tray, 32 ... Feed roller, 34 ... Transport drive roller, 36 ... Transport driven roller, 38 ... 1st roller, 40 ... Second roller, 42 ... Endless belt, 42a ... Upper section of endless belt, 44 ... Support, 46 ... Head holder, 48 ... Inkjet head, 50 ... First branch, 52 ... Inversion path, 54 ... Second branch, 56 ... Discharge roller pair, 64 ... Discharge drive roller, 68 ... drive shaft, 76 ... mounting surface, 78 ... convex portion, 80 ... first urging member, 82 ... second urging member, 84.86 ... support shaft, P ... recording medium

Claims (10)

A water-based inkjet ink composition containing a pigment, 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and an organic amine.
The aqueous inkjet ink composition, the content of _{M A} of the pigment (mass%), the 1- (2-hydroxyalkyl) content of 2-pyrrolidone _{M B} (wt%), of the trimethyl glycine the content is taken as _{M C} (mass%) satisfy the relation _{M B ≦ M a ≦ M C} , water-based ink-jet ink composition. The water-based inkjet ink composition according to claim 1, wherein the pigment is a phthalocyanine pigment. The pigment is C.I. I. Pigment Blue 15: 3 and C.I. I. The water-based inkjet ink composition according to claim 1, which is at least one of Pigment Blue 15: 4. Content M _A of the pigment is less than 3 mass% or more and 8 wt%, water-based ink-jet ink composition according to any one of claims 1 to 3. The 1- is (2-hydroxyalkyl) -2-pyrrolidone content M _B, not more than 1 mass% to 5 mass%, the water-based ink-jet ink composition according to any one of claims 1 to 4 thing. The content M _C of trimethyl glycine is 5 mass% or more, the water-based ink-jet ink composition according to any one of claims 1 to 5. The aqueous inkjet ink composition according to any one of claims 1 to 6, wherein the organic amine is at least one of triethanolamine and tripropanolamine. The content of the organic amine of the aqueous inkjet ink composition is taken as M _{D (wt%)} satisfy the relation M _D ≦ M _B, according to any one of claims 1 to 7 Water-based inkjet ink composition. The first ink and the second ink having a color different from that of the first ink are included.
The first ink and the second ink each contain a pigment, 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and an organic amine, respectively.
Wherein each of the first ink and the second ink, _{M A} (wt%) the content of the pigment, the content of the 1- (2-hydroxyalkyl) -2-pyrrolidone _{M B} (wt%) , the content of the trimethyl glycine is taken as M _{C (wt%),} each of said first ink and said second ink satisfy the relationship of _{M B ≦ M a ≦ M C} , ink set. Two or more inks sealed with the same head cap contain pigments, 1- (2-hydroxyalkyl) -2-pyrrolidone, trimethylglycine, and organic amines, respectively.
Wherein each of the 2 or more ink, _{M A} (wt%) the content of the pigment, the content of the 1- (2-hydroxyalkyl) -2-pyrrolidone _{M B} (wt%), the trimethyl glycine of the content is taken as M _{C (wt%),} each of said two or more inks satisfy the relationship of _{M B ≦ M a ≦ M C} , an ink jet recording apparatus.

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