Water-based ink for inkjet recording, inkjet recording device, and inkjet recording method

Abstract

This invention provides an aqueous inkjet recording ink with excellent long-term stability, using phycocyanin as a coloring agent. [Solution] The aqueous inkjet recording ink of this disclosure comprises water, phycocyanin, a water-soluble organic solvent, and sugars, wherein the sugars are monosaccharides, oligosaccharides, or monosaccharides and oligosaccharides.

Description

Technical Field

[0001] The present disclosure relates to an aqueous ink for inkjet recording, an inkjet recording apparatus, and an inkjet recording method.

Background Art

[0002] Patent Document 1 discloses an ink for inkjet recording that contains only a coloring material made from a petroleum-derived raw material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, from the perspective of decarbonization, it is desired that the blue coloring material of ink for inkjet recording be replaced from a petroleum-derived raw material to a naturally-derived raw material obtained from plants.

[0005] Here, several naturally-derived raw materials exist for blue coloring materials, and among them, phycocyanin is a water-soluble pigment that exhibits a very vivid blue color and has attracted attention. On the other hand, ink for inkjet recording containing phycocyanin has a problem of low temporal stability.

[0006] Accordingly, the present disclosure aims to provide an aqueous ink for inkjet recording that uses phycocyanin as a colorant and has excellent temporal stability, an inkjet recording apparatus, and an inkjet recording method.

Means for Solving the Problems

[0007] To achieve the above object, the aqueous ink for inkjet recording of the present disclosure is: It contains water, phycocyanin, a water-soluble organic solvent, and sugars. The aforementioned sugars include monosaccharides, oligosaccharides, or monosaccharides and oligosaccharides.

[0008] The inkjet recording apparatus of this disclosure includes an inkjet head, which ejects the aqueous inkjet recording ink of this disclosure onto a recording medium.

[0009] The inkjet recording method of this disclosure includes a recording step of ejecting the aqueous inkjet recording ink of this disclosure from an inkjet head onto a recording medium and recording the ink on the recording medium. [Effects of the Invention]

[0010] This disclosure provides an aqueous ink for inkjet recording, an inkjet recording apparatus, and an inkjet recording method that use phycocyanin as a coloring agent and have excellent temporal stability. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic perspective view showing the configuration of an example of an inkjet recording apparatus according to this disclosure. [Modes for carrying out the invention]

[0012] In this disclosure, the term "weight" may be interpreted as "mass" unless otherwise specified. For example, "weight ratio" may be interpreted as "mass ratio" unless otherwise specified, and "weight%" may be interpreted as "mass%" unless otherwise specified.

[0013] In this disclosure, when a numerical range is indicated for each raw material and parameter, unless otherwise specified, the numerical range means a numerical range that includes the lower and upper limits that define the numerical range. For example, when a numerical range of "1 to 10" is indicated, the numerical range means a numerical range that includes the lower limit of 1 and the upper limit of 10 that define "1 to 10" (i.e., 1 or more and 10 or less). Furthermore, when multiple upper limits and / or multiple lower limits are given as examples in this disclosure, any example upper and lower limits can be combined as the upper and lower limits of the numerical range.

[0014] The "weight %" figures presented in this disclosure are displayed to two decimal places and rounded to the third decimal place.

[0015] In the following embodiments and examples, when referring to mechanisms, the described mechanisms are merely presumed and are not limited to those described.

[0016] <Water-based ink for inkjet recording> The water-based inkjet recording inks of this disclosure (hereinafter sometimes referred to as "water-based inks" or "inks") will now be described. The water-based inks of this disclosure are, for example, colored water-based inks. The colored water-based inks are, for example, water-based inks containing a coloring agent as described later.

[0017] The aqueous ink of this disclosure comprises water, a colorant, a water-soluble organic solvent, and sugars. The water may be deionized water, pure water, or the like.

[0018] The aqueous inks of this disclosure have a water content of, for example, 10.00% to 90.00% by weight, or 20.00% to 80.00% by weight, relative to the total weight of the aqueous ink. The water content may be, for example, the remainder of the other raw materials.

[0019] The aqueous ink of the present disclosure is a cyan ink containing at least phycocyanin as the colorant. The aqueous ink of the present disclosure may be a cyan ink containing only phycocyanin as the colorant.

[0020] Furthermore, the aqueous ink of the present disclosure may, for example, be a cyan ink further containing a blue dye such as gardenia blue in addition to phycocyanin as the colorant. Moreover, the aqueous ink of the present disclosure may contain a red dye such as gardenia red or monascus red in addition to phycocyanin as the colorant. Further, the aqueous ink of the present disclosure may contain a yellow dye such as gardenia yellow or safflower yellow in addition to phycocyanin as the colorant. In this case, the aqueous ink of the present disclosure is an ink of a color such as purple or green.

[0021] In the aqueous ink of the present disclosure, the lower limit of the content of the phycocyanin based on the total weight of the entire aqueous ink may be, for example, 5.00 wt% or more, or 10.00 wt% or more. The upper limit of the content of the phycocyanin based on the total weight of the entire aqueous ink may be, for example, 15.00 wt% or less, or 10.00 wt% or less. The content of the phycocyanin based on the total weight of the entire aqueous ink may be, for example, 5.00 wt% to 15.00 wt%, 5.00 wt% to 10.00 wt%, or 10.00 wt% to 15.00 wt%.

[0022] Furthermore, the aqueous ink of the present disclosure may, for example, be an ink further containing a petroleum-derived pigment in addition to phycocyanin as the colorant. By containing phycocyanin and the petroleum-derived pigment as the colorant, it is possible to reduce the content of the petroleum-derived pigment contained in the aqueous ink, for example, compared with the case where only the petroleum-derived pigment is contained.

[0023] Examples of the petroleum-derived pigment include carbon black, inorganic pigments, organic pigments, and the like. Examples of the carbon black include furnace black, lamp black, acetylene black, channel black, and the like. Examples of the inorganic pigments include titanium oxide, iron oxide-based inorganic pigments, carbon black-based inorganic pigments, and the like. Examples of the organic pigments include azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye lake pigments such as basic dye-type lake pigments and acid dye-type lake pigments; nitro pigments; nitroso pigments; aniline black daylight fluorescent pigments; and the like. Other pigments may also be used as long as they are dispersible in an aqueous phase. Specific examples of the pigment include C.I. Pigment White 1, 4, 5, 6, 7, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, and 28; C.I. Pigment Black 1, 6 and 7; C.I. Pigment Yellow 1, 2, 3, 12, 13, 14, 15, 16, 17, 55, 74, 78, 150, 151, 154, 180, 185 and 194; C.I. Pigment Orange 31 and 43; C.I. Pigment Red 2, 3, 5, 6, 7, 12, 15, 16, 48, 48:1, 53:1, 57, 57:1, 112, 122, 123, 139, 144, 146, 149, 150, 166, 168, 175, 176, 177, 178, 184, 185, 190, 202, 209, 221, 222, 224 and 238; C.I. Pigment Violet 19 and 196; C.I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 16, 22 and 60; C.I. Pigment Green 7 and 36; and solid solutions of the aforementioned pigments, and the like.

[0024] The pigment may be dispersed in a solvent by a resin dispersant (also called a resin-dispersed pigment). The resin dispersant may be, for example, a conventionally known polymer dispersant (also called a pigment dispersion resin or resin dispersant, etc.). In addition, in the aqueous ink of this disclosure, the pigment may be encapsulated by a polymer. The resin dispersant may be, for example, one containing at least one of methacrylic acid and acrylic acid as a monomer, and commercially available products may be used. The resin dispersant may be, for example, a hydrophobic monomer such as styrene, styrene derivatives, vinylnaphthalene, vinylnaphthalene derivatives, or aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids, or a block copolymer, graft copolymer, or random copolymer or a salt thereof, consisting of two or more monomers selected from the group consisting of acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, or fumaric acid derivatives. Examples of the aforementioned commercially available products include BASF's "Joncryl® 611," "Joncryl® 60," "Joncryl® 586," "Joncryl® 687," "Joncryl® 63," and "Joncryl® HPD296"; Bic Chemie's "Disperbyk190" and "Disperbyk191"; and Lubrizol Corporation's "Solspers 20000" and "Solspers 27000."

[0025] A method for dispersing the pigment using the aforementioned pigment dispersion resin includes, for example, a method of dispersing the pigment using a dispersion apparatus. The dispersion apparatus used for dispersing the pigment is not particularly limited as long as it is a general-purpose dispersion machine, but examples include ball mills, roll mills, sand mills (e.g., high-speed type), etc.

[0026] The pigment may be a self-dispersing pigment. The self-dispersing pigment is such that, for example, at least one of a hydrophilic functional group such as a carbonyl group, hydroxyl group, carboxylic acid group, sulfonic acid group, or phosphate group, and its salts, is introduced into the pigment particles by chemical bonding, either directly or via other groups, so that it can be dispersed in water without the use of a dispersant. The self-dispersing pigment may be one in which the pigment has been treated by the method described in, for example, Japanese Patent Publication No. Hei 8-3498, Japanese Patent Publication No. 2000-513396, Japanese Patent Publication No. 2008-524400, Japanese Patent Publication No. 2009-515007, Japanese Patent Publication No. 2011-515535, etc. The raw material for the self-dispersing pigment may be either an inorganic pigment or an organic pigment. Examples of pigments suitable for the above treatment include carbon black such as "MA8" and "MA100" manufactured by Mitsubishi Chemical Corporation. The self-dispersing pigment may be a commercially available product, for example. Examples of the aforementioned commercially available products include "CAB-O-JET(registered trademark) 200", "CAB-O-JET(registered trademark) 250C", "CAB-O-JET(registered trademark) 260M", "CAB-O-JET(registered trademark) 270Y", "CAB-O-JET(registered trademark) 300", "CAB-O-JET(registered trademark) 400", "CAB-O-JET(registered trademark) 450C", "CAB-O-JET(registered trademark) 465M", and "CAB-O-JET(registered trademark) 470Y" from Cabot Corporation; "BONJET(registered trademark) BLACK CW-2" and "BONJET(registered trademark) BLACK CW-3" from Orient Chemical Industry Co., Ltd.; and "LIOJET(registered trademark) WD BLACK 002C" from artience Co., Ltd.

[0027] Furthermore, the aqueous ink of this disclosure may also contain, for example, a petroleum-derived dye in addition to phycocyanin as the coloring agent. By including both phycocyanin and the petroleum-derived dye as the coloring agent, the amount of petroleum-derived dye contained in the aqueous ink can be reduced compared to, for example, a case in which only the petroleum-derived dye is included.

[0028] The petroleum-derived dyes are not particularly limited and include, for example, direct dyes, acid dyes, basic dyes, and reactive dyes. Specific examples of the dyes include, for example, CI Direct Black, CI Direct Blue, CI Direct Red, CI Direct Yellow, CI Direct Orange, CI Direct Violet, CI Direct Brown, CI Direct Green, CI Acid Black, CI Acid Blue, CI Acid Red, CI Acid Yellow, CI Acid Orange, CI Acid Violet, CI Basic Black, CI Basic Blue, CI Basic Red, CI Basic Violet, and CI Food Black. Examples of CI Direct Black include CI Direct Black 17, 19, 32, 51, 71, 108, 146, 154, and 168. Examples of CI Direct Blue include CI Direct Blue 6, 22, 25, 71, 86, 90, 106, and 199. Examples of CI Direct Red include CI Direct Red 1, 4, 17, 28, 83, and 227. Examples of CI Direct Yellow include CI Direct Yellow 12, 24, 26, 86, 98, 132, 142, and 173. Examples of CI Direct Orange include CI Direct Orange 34, 39, 44, 46, and 60. Examples of CI Direct Violet include CI Direct Violet 47 and 48. Examples of CI Direct Brown include CI Direct Brown 109. Examples of CI Direct Green include CI Direct Green 59. Examples of CI Acid Black include CI Acid Black 2, 7, 24, 26, 31, 52, 63, 112, and 118. Examples of the aforementioned CI Acid Blue include CI Acid Blue 9, 22, 40, 59, 90, 93, 102, 104, 117, 120, 167, 229, and 234.Examples of the aforementioned CI Acid Red include CI Acid Red 1, 6, 32, 37, 51, 52, 80, 85, 87, 92, 94, 115, 180, 256, 289, 315, and 317. Examples of the aforementioned CI Acid Yellow include CI Acid Yellow 11, 17, 23, 25, 29, 42, 61, and 71. Examples of the aforementioned CI Acid Orange include CI Acid Orange 7 and 19. Examples of the aforementioned CI Acid Violet include CI Acid Violet 49. Examples of the aforementioned CI Basic Black include CI Basic Black 2. Examples of the aforementioned CI Basic Blue include CI Basic Blue 1, 3, 5, 7, 9, 24, 25, 26, 28, and 29. Examples of the aforementioned CI Basic Red include CI Basic Red 1, 2, 9, 12, 13, 14, and 37. Examples of the aforementioned CI Basic Violet include CI Basic Violet 7, 14, and 27. Examples of the aforementioned CI Hood Black include CI Hood Black 1 and 2.

[0029] Examples of the water-soluble organic solvents used in the aqueous inks of this disclosure include wetting agents and surfactants.

[0030] Examples of the wetting agents include lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones such as acetone; keto alcohols such as diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethers such as polyalkylene glycol; alkylene glycols; polyhydric alcohols such as glycerin, trimethylolpropane, and trimethylolethane; 2-pyrrolidone; N-methyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone; and the like. Examples of the polyalkylene glycols include polyethylene glycol and polypropylene glycol. Examples of the alkylene glycols include ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, thiodiglycol, and hexylene glycol. The aforementioned humectant may consist of one type of humectant, or it may consist of two or more types of humectants.

[0031] The aqueous inks of this disclosure may contain, for example, a wetting agent content of 1.00 to 20.00% by weight, 5.00 to 20.00% by weight, 5.00 to 15.00% by weight, or 10.00 to 15.00% by weight of the total weight of the aqueous ink.

[0032] The surfactant is not particularly limited and can be appropriately selected depending on the purpose; for example, commercially available products may be used. Specifically, examples of the surfactant include silicone-based surfactants and acetylene-based surfactants.

[0033] Examples of commercially available silicone-based surfactants include "Sylface® SAG002", "Sylface® SAG005", and "Sylface® SAG503A" manufactured by Nisshin Chemical Industry Co., Ltd.

[0034] Examples of commercially available acetylene-based surfactants include "Orphin® E1004," "Orphin® E1008," and "Orphin® E1010" manufactured by Nisshin Chemical Industry Co., Ltd.; "Surfinol® 440," "Surfinol® 465," and "Surfinol® 485" manufactured by Nisshin Chemical Industry Co., Ltd.; and "Acetylenel® E40" and "Acetylenel® E100" manufactured by Kawaken Fine Chemical Co., Ltd.

[0035] The aqueous ink may contain other surfactants in addition to / instead of the silicone-based surfactant and the acetylene-based surfactant. Examples of these other surfactants include the nonionic surfactant "Genagen C 100 SG" manufactured by CLARIANT. Nonionic surfactants manufactured by Kao Corporation, such as "Vita," the "EMULGEN®" series, "RHEODOL®" series, "EMASOL®" series, "EXCEL®" series, "EMANON®" series, "AMIET®" series, and "AMINON®" series; nonionic surfactants manufactured by Toho Chemical Industry Co., Ltd., such as the "SOLBO®" series; nonionic surfactants manufactured by Lion Corporation, such as the "DOBANOX®" series, "LEOCOL®" series, "LEOX®" series, "LAOL,LEOCOL®" series, "LIONOL®" series, "CADENAX®" series, "LIONON®" series, and "LEOFAT®" series; anionic surfactants manufactured by Kao Corporation, such as the "EMAL®" series, "LATEMUL®" series, "VENOL®" series, "NEOPELEX®" series, NS SOAP, KS SOAP, OS Examples include SOAP and the "PELEX®" series; anionic surfactants manufactured by Lion Corporation, such as the "LIPOLAN®" series, "LIPON®" series, "SUNNOL®" series, "LIPOTAC® TE,ENAGICOL" series, "LIPAL®" series, and "LOTAT®" series; and cationic surfactants manufactured by Daiichi Kogyo Seiyaku Co., Ltd., such as "Kachiogen® ES-OW" and "Kachiogen® ES-L".

[0036] The surfactant may be one type of surfactant or two or more types of surfactants.

[0037] The aqueous inks of this disclosure have a surfactant content of, for example, 0.10% to 10.00% by weight, or 0.50% to 5.00% by weight, relative to the total weight of the aqueous ink.

[0038] The aqueous inks of this disclosure include monosaccharides, oligosaccharides, or monosaccharides and oligosaccharides as the sugars. The sugars do not necessarily have to include disaccharides, for example. Furthermore, the sugars do not necessarily have to include polysaccharides, for example.

[0039] In this disclosure, "oligosaccharide" refers to an oligomer of sugars in which 3 to 9 monosaccharides are linked together by glycosidic bonds. In this disclosure, "polysaccharide" refers to a polymer of sugars in which 10 or more monosaccharides are linked together by glycosidic bonds.

[0040] Examples of the monosaccharides include glucose, galactose, fructose, mannose, xylose, arabinose, allose, tagatose, rhamnose, fucose, talose, and sorbose. For example, one monosaccharide may be used, or two or more monosaccharides may be used. When two or more monosaccharides are used, examples of combinations include glucose and galactose, glucose and fructose, galactose and fructose, or glucose, galactose, and fructose, but other combinations are also acceptable.

[0041] Examples of the oligosaccharides include fructooligosaccharides, galactooligosaccharides, raffinose, isomaltoligosaccharides, and maltotriose. For example, one type of oligosaccharide may be used, or two or more types of oligosaccharides may be used. When two or more types of oligosaccharides are used, examples of combinations include fructooligosaccharides and galactooligosaccharides, fructooligosaccharides and raffinose, galactooligosaccharides and raffinose, or fructooligosaccharides, galactooligosaccharides, and raffinose, but other combinations are also acceptable.

[0042] The aqueous ink of this disclosure includes, for example, one type of monosaccharide and one type of oligosaccharide as the monosaccharide and oligosaccharide. Specifically, the one type of monosaccharide and one type of oligosaccharide may be, for example, glucose and fructooligosaccharide, glucose and galactooligosaccharide, glucose and raffinose, galactose and fructooligosaccharide, galactose and galactooligosaccharide, galactose and raffinose, fructose and fructooligosaccharide, fructose and galactooligosaccharide, and fructose and raffinose.

[0043] Furthermore, the aqueous ink of this disclosure includes, for example, two types of monosaccharides and one type of oligosaccharide as the monosaccharides and oligosaccharides. Specifically, the two types of monosaccharides and one type of oligosaccharide include, for example, glucose and galactose and fructooligosaccharide, glucose and galactose and galactooligosaccharide, glucose and galactose and raffinose, glucose and fructose and fructooligosaccharide, glucose and fructose and galactooligosaccharide, glucose and fructose and raffinose, galactose and fructose and fructooligosaccharide, galactose and fructose and galactooligosaccharide, and galactose and fructose and raffinose.

[0044] Furthermore, the aqueous ink of this disclosure includes, for example, one type of monosaccharide and two types of oligosaccharides as the monosaccharide and oligosaccharide. Specifically, the one type of monosaccharide and two types of oligosaccharides include, for example, glucose and fructooligosaccharide and galactooligosaccharide, glucose and fructooligosaccharide and raffinose, glucose and galactooligosaccharide and raffinose, galactose and fructooligosaccharide and galactooligosaccharide, galactose and fructooligosaccharide and raffinose, galactose and galactooligosaccharide and raffinose, fructose and fructooligosaccharide and galactooligosaccharide, fructose and fructooligosaccharide and raffinose, and fructose and galactooligosaccharide and raffinose.

[0045] Furthermore, the aqueous ink of this disclosure includes, for example, three types of monosaccharides and one type of oligosaccharide as the monosaccharides and oligosaccharides. Specifically, the three types of monosaccharides and one type of oligosaccharide include, for example, glucose, galactose, fructose, and fructooligosaccharides; glucose, galactose, fructose, and galactooligosaccharides; and glucose, galactose, fructose, and raffinose.

[0046] Furthermore, the aqueous ink of this disclosure includes, for example, one type of monosaccharide and three types of oligosaccharides as the monosaccharide and oligosaccharide. Specifically, the one type of monosaccharide and three types of oligosaccharides include, for example, glucose, fructooligosaccharide, galactooligosaccharide and raffinose, galactose, fructooligosaccharide and galactooligosaccharide and raffinose, and fructose, fructooligosaccharide and galactooligosaccharide and raffinose.

[0047] Furthermore, the aqueous ink of this disclosure includes, for example, two types of monosaccharides and two types of oligosaccharides as the monosaccharides and oligosaccharides. Specifically, the two types of monosaccharides and two types of oligosaccharides include, for example, glucose and galactose and fructooligosaccharide and galactooligosaccharide, glucose and galactose and fructooligosaccharide and raffinose, glucose and galactose and galactooligosaccharide and raffinose, glucose and fructose and fructooligosaccharide and galactooligosaccharide, glucose and fructose and fructooligosaccharide and raffinose, glucose and fructose and galactooligosaccharide and raffinose, galactose and fructose and fructooligosaccharide and galactooligosaccharide, galactose and fructose and fructooligosaccharide and raffinose, and galactose and fructose and galactooligosaccharide and raffinose.

[0048] Furthermore, the aqueous ink of this disclosure includes, for example, three types of monosaccharides and two types of oligosaccharides as the monosaccharides and oligosaccharides. Specifically, the three types of monosaccharides and two types of oligosaccharides include, for example, glucose, galactose, fructose, fructooligosaccharides, and galactooligosaccharides; glucose, galactose, fructose, fructooligosaccharides, and raffinose; and glucose, galactose, fructose, galactooligosaccharides, and raffinose.

[0049] Furthermore, the aqueous ink of this disclosure includes, for example, two types of monosaccharides and three types of oligosaccharides as the monosaccharides and oligosaccharides. Specifically, the two types of monosaccharides and three types of oligosaccharides include glucose, galactose, fructooligosaccharides, galactooligosaccharides and raffinose, glucose, fructose, fructooligosaccharides, galactooligosaccharides and raffinose, and galactose, fructose, fructooligosaccharides, galactooligosaccharides and raffinose, etc.

[0050] Furthermore, the aqueous ink of this disclosure includes, for example, three types of monosaccharides and three types of oligosaccharides as the monosaccharides and oligosaccharides. Specifically, the three types of monosaccharides and three types of oligosaccharides include, for example, glucose, galactose, fructose, fructooligosaccharides, galactooligosaccharides, and raffinose.

[0051] Furthermore, the aqueous inks of this disclosure may be combinations of monosaccharides and oligosaccharides other than those mentioned above. In addition, the aqueous inks of this disclosure may be combinations of the monosaccharides and oligosaccharides mentioned above with monosaccharides and oligosaccharides other than those mentioned above.

[0052] The water-based ink of this disclosure may have a sugar content of, for example, a lower limit of 1.00% by weight or more, 5.00% by weight or more, 10.00% by weight or more, 15.00% by weight or more, or 20.00% by weight or more in the total weight of the water-based ink. Furthermore, the sugar content of, for example, a upper limit of 20.00% by weight or less, 15.00% by weight or less, 10.00% by weight or less, or 5.00% by weight or less in the total weight of the water-based ink. The sugar content of, for example, a sugar content of, a water-based ink may be between 5.00% by weight and 20.00% by weight.

[0053] If the aqueous ink of this disclosure contains glucose as the monosaccharide, the glucose content in the total weight of the aqueous ink may be, for example, 10.00% by weight or more.

[0054] If the aqueous ink of this disclosure contains fructose as the monosaccharide, the fructose content in the total weight of the aqueous ink may be, for example, 15.00% by weight or more.

[0055] If the aqueous ink of this disclosure contains galactose as the monosaccharide, the galactose content in the total weight of the aqueous ink may be, for example, 15.00% by weight or more.

[0056] If the aqueous ink of this disclosure contains the fructooligosaccharide as the oligosaccharide, the content of the fructooligosaccharide in the total weight of the aqueous ink may be, for example, 10.00% by weight or more.

[0057] If the aqueous ink of this disclosure contains galactooligosaccharide as the oligosaccharide, the content of galactooligosaccharide in the total weight of the aqueous ink may be, for example, 15.00% by weight or more.

[0058] If the aqueous ink of this disclosure contains raffinose as the oligosaccharide, the content of raffinose in the total weight of the aqueous ink may be, for example, 20.00% by weight or more.

[0059] If the aqueous ink of this disclosure contains two or more monosaccharides as the monosaccharide, the total content of the two or more monosaccharides in the total weight of the aqueous ink may be, for example, 20.00% by weight or more. Also, for example, if the two monosaccharides are glucose and galactose, the total content of glucose and galactose in the total weight of the aqueous ink may be 20.00% by weight or more.

[0060] If the aqueous ink of this disclosure contains two or more types of oligosaccharides, the total content of the two or more types of oligosaccharides in the total weight of the aqueous ink may be, for example, 20.00% by weight or more. Also, if, for example, the two types of oligosaccharides are fructooligosaccharide and galactooligosaccharide, the total content of the fructooligosaccharide and galactooligosaccharide in the total weight of the aqueous ink may be 20.00% by weight or more.

[0061] The aqueous ink of this disclosure may contain, for example, 20.00% by weight or more of the monosaccharide and oligosaccharide in the total weight of the aqueous ink.

[0062] Furthermore, if the aqueous ink contains galactose or raffinose, crystals may precipitate upon drying. The inkjet head has a nozzle surface coated with a water-repellent layer. If crystals precipitate in the aqueous ink, the water-repellent layer may be scraped off by the precipitated crystals when the nozzle surface is wiped with a wiper member. Therefore, if the aqueous ink of this disclosure contains galactose or raffinose as the sugar, it is preferable that the content of galactose or raffinose in the total weight of the aqueous ink is, for example, 5.00% by weight or less, or 10.00% by weight or less.

[0063] The aqueous inks of this disclosure may further contain, as necessary, raw materials such as pH adjusters, viscosity adjusters, preservatives, and fungicides. Alternatively, the aqueous inks of this disclosure may contain, for example, only plant-derived raw materials. That is, in the aqueous inks of this disclosure, for example, all components except water may be plant-derived.

[0064] <Inkjet recording device, inkjet recording method> Next, the inkjet recording apparatus and inkjet recording method of this disclosure will be described.

[0065] The inkjet recording apparatus of this disclosure includes an inkjet head, which ejects the aqueous inkjet recording ink of this disclosure onto a recording medium. The aqueous ink of this disclosure is a cyan ink containing only phycocyanin as the coloring agent.

[0066] Figure 1 shows the configuration of an example of the inkjet recording device. As shown in the figure, this inkjet recording device 1 mainly includes an ink cartridge 101, an inkjet head 102, a carriage 103, a drive unit 105, a platen roller 106, and a purge device 107. Although not shown, the ink cartridge 101 and the inkjet head 102 may be connected by an ink channel, and the aqueous ink contained in the ink cartridge 101 may be supplied to the ink channel, and the inkjet head 102 may apply the aqueous ink to the recording medium P which is to be recorded. The recording medium P may be, for example, plain paper, glossy paper, etc.

[0067] The ink cartridge 101 contains the aqueous ink. The housing of the ink cartridge that contains the aqueous ink may be, for example, a conventionally known one.

[0068] The inkjet head 102 ejects ink toward the recording medium P to be recorded. The carriage 103 is equipped with an ink cartridge 101 and a head unit 104. The drive unit 105 moves the carriage 103 back and forth in the main scanning direction. When recording an image on the recording medium P, the inkjet head 102 ejects ink while the carriage 103 moves back and forth in the main scanning direction, thereby recording on the recording medium P. For example, a conventionally known drive unit 105 may be used (see, for example, Japanese Patent Application Publication No. 2008-246821). The platen roller 106 extends in the main scanning direction.

[0069] The purging device 107 sucks up defective ink containing air bubbles and other impurities that accumulate inside the inkjet head 102. For example, a conventionally known purging device 107 may be used (see, for example, Japanese Patent Application Publication No. 2008-246821).

[0070] As shown in Figure 1, in the main scanning direction, a wiper member 109 is positioned adjacent to the purge device 107 between the purge device 107 and the platen roller 106. The wiper member 109 is a rubber plate-shaped blade that wipes the nozzle forming surface of the inkjet head 102 as the carriage 103 moves.

[0071] In Figure 1, the cap 108 contacts the nozzle-forming surface of the inkjet head 102 and covers multiple nozzles. When recording is complete, the carriage 103 moves to a standby position where the inkjet head 102 faces the cap 108. Then, the cap 108 approaches the inkjet head 102, contacts the nozzle-forming surface, and covers multiple nozzles provided on the nozzle-forming surface.

[0072] In the inkjet recording device 1 of this example, the ink cartridge 101 is mounted on the carriage 103 together with the inkjet head 102, but this is not particularly limited. For example, the ink cartridge 101 may not be mounted on the carriage 103, but may be located inside the inkjet recording device 1. Specifically, the ink cartridge 101 and the inkjet head 102 mounted on the carriage 103 are fluidly connected via the ink flow path such as a tube, and the ink is supplied from the ink cartridge 101 to the inkjet head 102. Alternatively, a bottle-shaped ink bottle may be used instead of the ink cartridge 101. In this case, the inkjet recording device 1 is equipped with an ink tank fixed inside, and the ink tank has an inlet. The user inserts the ink bottle into the inlet of the ink tank and replenishes the ink from the ink bottle into the ink tank.

[0073] The recording process using this inkjet recording device 1 is carried out, for example, as follows. First, a recording medium P is supplied from the rear or below the inkjet recording device 1. The recording medium P is transported by the platen roller 106 to the area facing the inkjet head 102. Once transported, the recording medium P is used to record an image or the like by ejecting aqueous ink from the inkjet head 102. After recording, the recording medium P is discharged from the inkjet recording device 1. In Figure 1, the transport mechanism and discharge mechanism until the recording medium P reaches the platen roller 106 are not shown.

[0074] The apparatus shown in Figure 1 employs a serial inkjet head, but a line-type inkjet head may also be used. Furthermore, the apparatus shown in Figure 1 may employ a roll-to-roll system where the leading edge of the roll paper is wound up by a winding machine. The serial inkjet head prints by reciprocating the inkjet head in the width direction of the recording medium. A line-type inkjet head is longer than the maximum width of the recording medium that the inkjet recording device 1 can record on, and the inkjet head does not reciprocate in the width direction. An inkjet recording device equipped with a line-type inkjet head prints by ejecting ink from the inkjet head toward the paper while transporting the paper.

[0075] Next, the inkjet recording method of this disclosure is an inkjet recording method that includes a recording step of ejecting the aqueous ink from an inkjet head onto a recording medium and recording it on the recording medium. The inkjet recording method of this disclosure can be carried out, for example, using the inkjet recording apparatus of this disclosure. The recording includes printing of characters and images. [Examples]

[0076] Next, embodiments of this disclosure will be described together with comparative examples. However, this disclosure is not limited to or restricted by the embodiments and comparative examples described below.

[0077] (Examples 1-27, Comparative Examples 1-3) The raw materials excluding the colorants in the aqueous ink compositions shown in Tables 1-3 below, 10.00% by weight of glycerin, and 0.50% by weight of a surfactant (nonionic surfactant "Genagen C 100 SG Vita" manufactured by CLARIANT) were uniformly mixed to obtain an ink solvent. Next, the colorants were added to the ink solvent and uniformly mixed to obtain the aqueous inkjet recording inks of Examples 1-27 and Comparative Examples 1-3 shown in Tables 1-3.

[0078] For each of the aqueous inks in Examples 1-27 and Comparative Examples 1-3, (a) stability over time, (b) evaporation characteristics, and (c) feasibility of homogenization were evaluated using the following methods.

[0079] (a) Stability over time Five g of each aqueous ink from Examples 1-27 and Comparative Examples 1-3 was weighed into glass bottles and stored in a constant temperature bath at 50°C for seven days. The aqueous inks before and after storage were each diluted 150 times with pure water, and their absorbance was measured. The peak top values ​​in the 400-800 nm range of the absorbance spectra obtained from each aqueous ink before and after storage were acquired, and the rate of change from the value before storage to the value after storage was calculated using the following formula (1). Subsequently, the time-dependent stability was evaluated according to the evaluation criteria below. Percentage change in absorbance (%) = (Absorbance before storage - Absorbance after storage) × 100 / Absorbance before storage (1)

[0080] Furthermore, if the product has high stability over time, for example, the color of the ink stored in a transparent or translucent ink cartridge will not change over time, and there will be no visual difference between a new and an old cartridge.

[0081] Evaluation criteria for stability over time AA: Absorbance change rate is less than 10% A: Absorbance change rate of 10% or more but less than 15% B: Absorbance change rate is 15% or more but less than 20% C: Absorbance change rate is 20% or more

[0082] (b) Evaporation characteristics The aqueous inks of Examples 1-27 and Comparative Examples 1-3 were dropped one drop at a time onto a glass slide using a 1 mL dropper and dried in a 50°C constant temperature bath for one day. The dried inks were observed under a microscope (200x magnification), and their evaporation characteristics were evaluated according to the following evaluation criteria.

[0083] Evaporation characteristics evaluation criteria ○: No crystal precipitation ×: Crystal precipitation present

[0084] (c) Feasibility of homogenization The aqueous inks of Examples 1-27 and Comparative Examples 1-3 were mixed using a magnetic stirrer for at least 15 minutes. The uniformity of the mixed aqueous inks was evaluated according to the following evaluation criteria.

[0085] Evaluation criteria for feasibility of homogenization ○: No separation of water-based ink was observed. ×: Separation of water-based ink was observed.

[0086] The separation of water-based inks was evaluated visually. In the evaluation of homogenization, samples in which the water-based ink raw materials precipitated and became insoluble in water, or in which the raw materials gelled, were evaluated as "separation of water-based inks was observed." Samples in which the water-based ink raw materials dissolved in water and no precipitate was observed were evaluated as "no separation of water-based inks was observed."

[0087] Tables 1-3 show the aqueous ink compositions and evaluation results of the aqueous inks used in Examples 1-27 and Comparative Examples 1-3.

[0088] [Table 1]

[0089] [Table 2]

[0090] [Table 3]

[0091] As shown in Tables 1-3, all of Examples 1-27 showed a time-dependent stability rating of "B" or higher. Furthermore, all also showed a homogenization rating of "〇".

[0092] Furthermore, Examples 1-8, 17-20, and 25-27, which used glucose, galactose, glucose and galactose, galactooligosaccharides, or fructooligosaccharides and galactooligosaccharides as sugars, showed a time-dependent stability of "A" or higher. Even when fructose was used as the sugar, Examples 11 and 12, where the fructose content in the total weight of the aqueous ink was 15.00% by weight or more, showed a time-dependent stability of "A" or higher. Similarly, even when fructooligosaccharides were used as the sugar, Examples 14-16, where the fructooligosaccharide content in the total weight of the aqueous ink was 10.00% by weight or more, showed a time-dependent stability of "A" or higher.

[0093] Furthermore, in Examples 2-4, where glucose was used as the sugar and the glucose content in the total weight of the aqueous ink was 10.00% by weight or more, the stability over time was "AA" or higher. In Examples 7 and 8, where galactose was used as the sugar and the galactose content in the total weight of the aqueous ink was 15.00% by weight or more, the stability over time was also "AA" or higher. In Example 25, where glucose and galactose were used as the sugars, the stability over time was also "AA" or higher. In Examples 19 and 20, where galactooligosaccharide was used as the sugar and the galactooligosaccharide content in the total weight of the aqueous ink was 15.00% by weight or more, the stability over time was also "AA" or higher. In Example 24, where raffinose was used as the sugar and the raffinose content in the total weight of the aqueous ink was 20.00% by weight or more, the stability over time was also "AA" or higher. Example 27, which used fructooligosaccharides and galactooligosaccharides as sugars, also showed a time-dependent stability rating of "AA" or higher. Examples 25-27, which used two or more monosaccharides, two or more oligosaccharides, or monosaccharides and oligosaccharides as sugars, and in which the sugar content in the total weight of the aqueous ink was 20.00% by weight or more, also showed a time-dependent stability rating of "AA" or higher.

[0094] In addition, Examples 1-4, 9-12, 13-20, 26, and 27, which used glucose, fructose, fructooligosaccharides, galactooligosaccharides, two or more types of oligosaccharides, or monosaccharides and oligosaccharides as sugars, showed "○" in terms of evaporation characteristics.

[0095] On the other hand, Comparative Example 1, which did not contain sugars, received a "C" rating for its stability over time. Comparative Examples 2 and 3, which contained the disaccharide cellobiose and the polysaccharide carrageenan as sugars, could not be homogenized.

[0096] The above embodiments and some or all of the examples may also be described as follows, but are not limited to these. (Note 1) It contains water, phycocyanin, a water-soluble organic solvent, and sugars. The aforementioned sugars are monosaccharides, oligosaccharides, or include monosaccharides and oligosaccharides. Water-based ink for inkjet recording. (Note 2) The aforementioned sugars are monosaccharides, Water-based inkjet recording ink as described in Appendix 1. (Note 3) The aforementioned sugars are the aforementioned oligosaccharides. Water-based inkjet recording ink as described in Appendix 1. (Note 4) The aforementioned sugars are the monosaccharides and the oligosaccharides. Water-based inkjet recording ink as described in Appendix 1. (Note 5) The monosaccharide is glucose, galactose, or glucose and galactose. Water-based inkjet recording ink as described in Appendix 2. (Note 6) The monosaccharide is fructose, In the total weight of the aforementioned aqueous ink, The fructose content is 15.00% by weight or more. Water-based inkjet recording ink as described in Appendix 2. (Note 7) The monosaccharide is glucose, In the total weight of the aforementioned aqueous ink, The glucose content is 10.00% by weight or more. Water-based inkjet recording ink as described in Appendix 2. (Note 8) The aforementioned monosaccharide is galactose, In the total weight of the aforementioned aqueous ink, The galactose content is 15.00% by weight or more. Water-based inkjet recording ink as described in Appendix 2. (Note 9) The monosaccharides are glucose and galactose. In the total weight of the aforementioned aqueous ink, The total content of glucose and galactose is 20.00% by weight or more. Water-based inkjet recording ink as described in Appendix 2. (Note 10) The monosaccharide is glucose or fructose. Water-based inkjet recording ink as described in Appendix 2. (Note 11) The oligosaccharide is galactooligosaccharide, or a combination of fructooligosaccharide and galactooligosaccharide. Water-based inkjet recording ink as described in Appendix 3. (Note 12) The aforementioned oligosaccharide is a fructooligosaccharide. In the total weight of the aforementioned aqueous ink, The fructooligosaccharide content is 10.00% by weight or more. Water-based inkjet recording ink as described in Appendix 3. (Note 13) The aforementioned oligosaccharide is galactooligosaccharide, In the total weight of the aforementioned aqueous ink, The galactooligosaccharide content is 15.00% by weight or more. Water-based inkjet recording ink as described in Appendix 3. (Note 14) The aforementioned oligosaccharide is raffinose, In the total weight of the aforementioned aqueous ink, The raffinose content is 20.00% by weight or more. Water-based inkjet recording ink as described in Appendix 3. (Note 15) The aforementioned oligosaccharides are fructooligosaccharides and galactooligosaccharides. In the total weight of the aforementioned aqueous ink, The total content of the fructooligosaccharide and the galactooligosaccharide is 20.00% by weight or more. Water-based inkjet recording ink as described in Appendix 3. (Note 16) The oligosaccharide is a fructooligosaccharide or a galactooligosaccharide. Water-based inkjet recording ink as described in Appendix 3. (Note 17) In the total weight of the aforementioned aqueous ink, The total content of the monosaccharide and the oligosaccharide is 20.00% by weight or more. Water-based inkjet recording ink as described in Appendix 1. (Note 18) The aforementioned sugars are two or more of the aforementioned oligosaccharides, or the aforementioned monosaccharide and the aforementioned oligosaccharide. Water-based inkjet recording ink as described in Appendix 1. (Note 19) Including the inkjet head, The aforementioned inkjet head ejects an aqueous inkjet recording ink described in any of appendices 1 to 18 onto a recording medium. Inkjet recording device. (Note 20) The recording process includes ejecting an inkjet water-based inkjet recording ink described in any of Appendix 1 to 18 from an inkjet head onto a recording medium, and recording the ink on the recording medium. Inkjet recording method. [Industrial applicability]

[0097] As described above, this disclosure provides an aqueous inkjet recording ink with excellent time-dependent stability, using phycocyanin as a coloring agent. The aqueous ink, inkjet recording apparatus, and inkjet recording method of this disclosure are widely applicable to inkjet recording on various recording media. [Explanation of Symbols]

[0098] 1. Inkjet recording device 101 Ink Cartridges 102 Inkjet Heads 103 Carriage 104 Head Unit 105 Drive Unit 106 Platen Roller 107 Purge device 108 Cap 109 Wiper components

Claims

1. It contains water, phycocyanin, a water-soluble organic solvent, and sugars. The aforementioned sugars are monosaccharides, oligosaccharides, or include monosaccharides and oligosaccharides. Water-based ink for inkjet recording.

2. The aforementioned sugars are monosaccharides, The aqueous ink for inkjet recording according to claim 1.

3. The aforementioned sugars are the aforementioned oligosaccharides. The aqueous ink for inkjet recording according to claim 1.

4. The aforementioned sugars are the monosaccharides and the oligosaccharides. The aqueous ink for inkjet recording according to claim 1.

5. The monosaccharide is glucose, galactose, or glucose and galactose. The aqueous ink for inkjet recording according to claim 2.

6. The monosaccharide is fructose, In the total weight of the aforementioned aqueous ink, The fructose content is 15.00% by weight or more. The aqueous ink for inkjet recording according to claim 2.

7. The monosaccharide is glucose, In the total weight of the aforementioned aqueous ink, The glucose content is 10.00% by weight or more. The aqueous ink for inkjet recording according to claim 2.

8. The aforementioned monosaccharide is galactose, In the total weight of the aforementioned aqueous ink, The galactose content is 15.00% by weight or more. The aqueous ink for inkjet recording according to claim 2.

9. The monosaccharides are glucose and galactose. In the total weight of the aforementioned aqueous ink, The total content of glucose and galactose is 20.00% by weight or more. The aqueous ink for inkjet recording according to claim 2.

10. The monosaccharide is glucose or fructose. The aqueous ink for inkjet recording according to claim 2.

11. The oligosaccharide is galactooligosaccharide, or a combination of fructooligosaccharide and galactooligosaccharide. The aqueous ink for inkjet recording according to claim 3.

12. The aforementioned oligosaccharide is a fructooligosaccharide. In the total weight of the aforementioned aqueous ink, The fructooligosaccharide content is 10.00% by weight or more. The aqueous ink for inkjet recording according to claim 3.

13. The aforementioned oligosaccharide is galactooligosaccharide, In the total weight of the aforementioned aqueous ink, The galactooligosaccharide content is 15.00% by weight or more. The aqueous ink for inkjet recording according to claim 3.

14. The aforementioned oligosaccharide is raffinose, In the total weight of the aforementioned aqueous ink, The raffinose content is 20.00% by weight or more. The aqueous ink for inkjet recording according to claim 3.

15. The aforementioned oligosaccharides are fructooligosaccharides and galactooligosaccharides. In the total weight of the aforementioned aqueous ink, The total content of the fructooligosaccharide and the galactooligosaccharide is 20.00% by weight or more. The aqueous ink for inkjet recording according to claim 3.

16. The oligosaccharide is a fructooligosaccharide or a galactooligosaccharide. The aqueous ink for inkjet recording according to claim 3.

17. In the total weight of the aforementioned aqueous ink, The total content of the monosaccharide and the oligosaccharide is 20.00% by weight or more. The aqueous ink for inkjet recording according to claim 1.

18. The aforementioned sugars are two or more of the aforementioned oligosaccharides, or the aforementioned monosaccharide and the aforementioned oligosaccharide. The aqueous ink for inkjet recording according to claim 1.

19. Including the inkjet head, The inkjet head ejects the aqueous inkjet recording ink described in any one of claims 1 to 18 onto a recording medium. Inkjet recording device.

20. The recording step includes ejecting an aqueous inkjet recording ink described in any one of claims 1 to 18 from an inkjet head onto a recording medium and recording the ink on the recording medium. Inkjet recording method.

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