Inkjet ink composition, recording method, and recorded matter

Abstract

To provide an ink jet ink composition, a recording method, and a recorded material that can achieve improved image quality and discharge stability.SOLUTION: An ink jet ink composition includes water, a phospholipid that forms a fine particle, and a coloring material that is incorporated in the fine particle.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an inkjet ink composition, a recording method, and a recorded matter. [Background technology]

[0002] In the past, inks using colorants derived from natural products have been known to reduce the burden on the environment. For example, Patent Document 1 discloses an ink composition containing a colorant that is natural or derived from a natural source, and a dispersant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-109031 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the ink composition described in Patent Document 1 has the problem that it is difficult to improve the image quality of recorded materials and the ejection stability from an inkjet head. Specifically, colorants derived from natural products may have restrictions on the molecular structure, such as substituents, compared to synthetic colorants. Because the molecular structure of the colorant is limited, ink compositions using colorants derived from natural products are more likely to cause bleeding on recorded materials when water-soluble colorants are used, and more likely to have poor ejection stability when water-insoluble colorants are used, compared to ink compositions using synthetic colorants. In other words, there has been a demand for inkjet ink compositions that improve the image quality and ejection stability of recorded materials even when using colorants derived from natural products. [Means for solving the problem]

[0005] The inkjet ink composition contains water, a phospholipid that forms fine particles, and a coloring material that is encapsulated in the fine particles.

[0006] The recording method includes a step of ejecting the inkjet ink composition from an inkjet head and depositing it onto a recording medium.

[0007] The recorded matter is formed by applying the ink-jet ink composition to a recording medium. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1. Inkjet ink composition The inkjet ink composition according to this embodiment contains water, a colorant, and a phospholipid. In the inkjet ink composition, the phospholipid forms fine particles that encapsulate the colorant. The fine particles encapsulate the colorant. In the following description, the inkjet ink composition according to this embodiment will be simply referred to as ink, and the fine particles formed by the phospholipid and encapsulating the colorant will also be simply referred to as fine particles. The various components contained in the ink will be described below.

[0009] 1.1.Water Water is the main solvent of the ink of this embodiment. In other words, the ink is an aqueous ink. Water is a component that evaporates when the ink dries after being applied to the recording medium. Examples of water that can be used include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water, which has had ionic impurities removed as much as possible. Furthermore, using water that has been sterilized by ultraviolet irradiation or the addition of hydrogen peroxide can prevent the growth of mold and bacteria when the treatment liquid is stored for a long period of time.

[0010] The water content of the ink is not particularly limited, but is preferably 5% by mass or more, and more preferably 7% by mass or more and 99% by mass or less, based on the total mass of the ink. Furthermore, 9% by mass or more and 80% by mass or less is preferred, even more preferably 10% by mass or more and 75% by mass or less, and more preferably 15% by mass or more and 70% by mass or less. Furthermore, 40% by mass or more and 70% by mass or less is preferred, and more preferably 50% by mass or more and 70% by mass or less. By keeping the water content within the above range, ejection properties from an inkjet head and drying properties after application to a recording medium are improved.

[0011] 1.2.Colorants When ink is applied to a recording medium, the colorant remains on the recording medium and exhibits a color specific to the colorant. Multiple colorants with different colors are used to create color images, patterns, text, and the like. The color that a colorant exhibits on a recording medium, i.e., the intensity of the color, is called colorability; the deeper the color, the better the colorability.

[0012] The coloring material used may be either a water-soluble coloring material or a water-insoluble coloring material. Note that a water-insoluble coloring material refers to a coloring material that has a solubility of less than 0.1 g in 100 g of water at 20°C, and in this specification, this term also includes coloring materials that are poorly soluble in water.

[0013] 1.2.1.Water-soluble colorants The water-soluble coloring material is a water-soluble dye. Examples of the water-soluble dye include acid dyes, direct dyes, and basic dyes. Known dyes can be used as the water-soluble dye. Hereinafter, the water-soluble dye may be simply referred to as a dye.

[0014] Examples of acid dyes include CI (Colour Index Generic Name) Acid Blue 1, 7, 9, 15, 22, 23, 25, 27, 29, 40, 41, 43, 45, 49, 54, 59, 60, 62, 72, 78, 80, 82, 83, 90, 92, 93, 100, 102, 103, 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 133, and 138. , 140, 142, 143, 151, 154, 158, 161, 166, 167, 168, 170, 171, 175, 182, 183, 184, 185, 187, 192, 193, 199, 203, 204, 205, 225, 229, 234, 236, 247, 249, 300, CI Acid Red 1, 6, 8, 9, 13, 14, 18, 19, 24, 26, 27, 28, 32, 35, 37, 42, 51, 52, 57, 62, 75, 77, 80, 82, 83, 85, 87, 88, 89, 92, 94, 95, 97, 106, 111, 114, 115, 117, 118, 119, 129, 130, 131, 133, 134, 138, 143, 145, 149, 154 , 155, 158, 168, 180, 183, 184, 186, 194, 198, 199, 209, 211, 215, 216, 217, 219, 249, 252, 254, 256, 257, 260, 263, 265, 266, 274, 276, 282, 283, 289, 303, 317, 318, 320, 321, 322, 361, 407, CI Acid Yellow 1, 3, 7, 11, 17, 19, 25, 29, 32, 36, 38, 40, 42, 44, 49, 59, 61, 70, 72, 75, 76, 78, 79, 98, 99, 110, 111, 112, 114, 116, 118, 119, 127, 128, 131, 135, 141, 142, 161, 162, 163, 164, 165, 169, 184, 207, 219, 246, CI Acid Black 1, 2, 7, 24, 26, 29, 31, 44, 48, 50, 51, 52, 52:1, 58, 60, 62, 63, 64, 67, 72, 76, 77, 94, 107, 108, 109 , 110, 112, 115, 118, 119, 121, 122, 131, 132, 139, 140, 155, 156, 157, 158, 159, 172, 191, 234, CIAcid Orange 1, 7, 8, 10, 19, 20, 24, 28, 33, 41, 43, 45, 51, 56, 63, 64, 65, 67, 74, 80, 82, 85, 86, 87, 88, 94, 122, 123, 124; CI Acid Violet 7, 11, 15, 31, 34, 35, 41, 43, 47, 48, 49, 51, 54, 66, 68, 75, 78, 97, 106; CI Acid Green 3, 7, 9, 12, 16, 19, 20, 25, 27, 28, 35, 36, 40, 41, 43, 44, 48, 56, 57, 60, 61, 65, 73, 75, 76, 78, 79; CI Acid Brown 2, 4, 13, 14, 19, 20, 27, 28, 30, 31, 39, 44, 45, 46, 48, 53, 100, 101, 103, 104, 106, 160, 161, 165, 188, 224, 225, 226, 231, 232, 236, 247, 256, 257, 266, 268, 276, 277, 282, 289, 294, 295, 296, 297, 298, 299, 300, 301, 302, etc.

[0015] Examples of direct dyes include CI Direct Blue 1, 2, 6, 9, 15, 22, 25, 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192, 193, 194, 195, 196, 200, 201, 202, 203, 207, 225, 226, 236, 237, 246, 248, and 249, and CI Direct Red. 1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231, CI Direct Yellow 1, 8, 11, 12, 24, 26, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 110, 132, 142, 144, CI Direct Black Examples include 17, 19, 22, 32, 35, 38, 51, 56, 62, 71, 74, 75, 77, 94, 105, 106, 107, 108, 112, 113, 117, 118, 132, 133, 146, 154, 168, and 171.

[0016] It is preferable to use animal- or plant-derived dyes as water-soluble colorants. Animal- or plant-derived refers to extracts from animals and plants, their fermented products, and processed products, etc., that do not use underground resources. This allows the use of colorants that are not derived from underground resources such as petroleum, thereby reducing the burden on the environment.

[0017] Examples of dyes derived from animals or plants include cochineal dye, gardenia yellow, safflower yellow, monascus yellow, saffron dye, monascus red dye, gardenia red dye, safflower red dye, beet red, perilla dye, hibiscus dye, red cabbage dye, red radish dye, purple sweet potato dye, purple corn dye, grape skin dye, red currant dye, purple carrot dye, berry dyes such as elderberry dye (extracts of cranberry, strawberry, blackberry, blueberry, hoisenberry, watermelon, raspberry, etc.), grape juice dye, gardenia blue dye, spirulina dye, butterfly pea dye, cacao dye, persimmon dye, caramel dye, sorghum dye, onion dye, tamarind dye, malt extract, seaweed dye, and porphyrin dye.

[0018] Dyes derived from animals or plants may be used that combine with metals to form chelate complexes, such as tin mordanting of cochineal dye. In this case, the dyes that form the chelate complexes are encapsulated and protected by fine particles. This reduces the interaction between the metal ions in the ink and the coloring material, thereby preventing discoloration in printed materials. Details of fine particles will be discussed later.

[0019] When a water-soluble colorant is used, its content is not particularly limited, but is preferably, for example, 0.5% by mass to 30.0% by mass, based on the total mass of the ink. It is more preferably 1.0% by mass to 25.0% by mass, and even more preferably 1.0% by mass to 20.0% by mass. It is further preferably 2.0% by mass to 10.0% by mass, and even more preferably 3.0% by mass to 6.0% by mass. By keeping the content of the water-soluble colorant within the above range, color development in the recorded matter is ensured, while an increase in ink viscosity and clogging of the nozzles in the inkjet head are suppressed.

[0020] 1.2.2.Water-insoluble colorants The water-insoluble coloring material may be an oil-soluble dye, a disperse dye, a pigment, etc. Known dyes may be used as the water-insoluble coloring material.

[0021] Examples of oil-soluble dyes include CI Solvent Black 3, 5, and 7, CI Solvent Yellow 2, 4, 7, 14, 16, 33, 56, and 93, CI Solvent Blue 5, 35, 70, and 94, CI Solvent Red 1, 3, 18, 19, 23, 24, 27, 49, and 197, CI Solvent Violet 8, CI Solvent Orange 2 and 7, CI Solvent Green 3, Nile Red, phenylazoresorcinol, quinizarin, and quinizarin blue.

[0022] Examples of disperse dyes include CI Disperse Blue 3, 7, 9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 73, 75, 79, 81, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 153, 1 54, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 330, 333, 360, CI Disperse Red 1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134, 135, 137, 143, 145, 146, 151 , 152, 153, 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 225, 227, 229, 239, 240, 257, 258, 277, 278, 279, 281, 288, 298, 302, 303, 310, 311, 312, 320, 324, 328Disperse Yellow 3, 4, 5, 7, 9, 13, 23, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63, 64, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 108, 114, 116, 118, 119, 1 22, 124, 126, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 184, 186, 192, 198, 199, 202, 204, 210, 211, 215, 216, 218, 224, 227, 231, 232, CI Disperse Black 1, 3, 10, 24, CI Disperse Orange 1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 46, 47, 48, 49, 50, 53, 54, 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142, CI Disperse Violet CI Disperse Green 9, CI Disperse Brown 1, 2, 4, 9, 13, 19, 20, 21, 22, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63, 69, 77, CI Disperse Green 9, CI Disperse Brown 1, 2, 4, 9, 13, 19, etc.

[0023] Known organic and inorganic pigments are used as the pigment. Examples of organic pigments include azo pigments such as azo lake pigments, insoluble azo pigments, condensed azo pigments, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, isoindoline pigments, quinophthalone pigments, and diketopyrrolopyrrole pigments; dye lake pigments such as basic dye lakes and acid dye lakes; nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments. Examples of inorganic pigments include metal oxide pigments such as titanium dioxide, zinc oxide, and chromium oxide; and carbon black. Luminescent pigments such as pearlescent pigments and metallic pigments may also be used.

[0024] Specifically, for example, CI Pigment Black 1, 7, and 11 are used for black ink, and CI Pigment White 6, 18, and 21 are used for white ink.

[0025] Examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 167, 172, and 180.

[0026] Examples of magenta pigments include CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48(Ca), 48(Mn), 57(Ca), 57:1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168, 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, and 245, and CI Pigment Violet. Examples include 19, 23, 32, 33, 36, 38, 43, and 50.

[0027] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:34, 15:4, 16, 18, 22, 25, 60, 65, and 66, and CI Vat Blue 4 and 60.

[0028] Examples of pigments for colors other than those mentioned above include CI Pigment Green 7 and 10, CI Pigment Brown 3, 5, 25 and 26, and CI Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43 and 63.

[0029] In addition to the above-mentioned water-insoluble coloring materials, known coloring materials such as leuco dyes may also be used.

[0030] As the water-insoluble colorant, it is preferable to use an oil-soluble dye or pigment of animal or plant origin. Examples of oil-soluble dyes of animal or plant origin include carotenoid pigments such as palm oil carotene, marigold pigment, tomato pigment, Haematococcus algae pigment, annatto pigment, and chili pepper pigment, as well as safflower red pigment, lac pigment, Indian indigo, turmeric, and beta-carotene. Examples of pigments of animal or plant origin include CI Pigment Black 7, which is based on plant charcoal such as binchotan charcoal and bamboo charcoal, as well as squid ink pigment, Indian indigo, lac pigment, and turmeric pigment. This allows the use of colorants that are not derived from underground resources such as petroleum, thereby reducing the burden on the environment.

[0031] The content of the water-insoluble colorant is not particularly limited, but is preferably, for example, 0.5% to 30.0% by mass relative to the total mass of the ink. It is more preferably 1.0% to 25.0% by mass, and even more preferably 1.0% to 20.0% by mass. It is further preferably 2.0% to 10.0% by mass, and even more preferably 3.0% to 6.0% by mass. By keeping the content of the water-insoluble colorant within the above range, color development in the recorded matter is ensured, while an increase in ink viscosity and clogging of the nozzles in the inkjet head are suppressed.

[0032] Phospholipids Phospholipids are amphiphilic lipids that contain a phosphate ester moiety and form fine particles in aqueous solvents.

[0033] Examples of phospholipids include natural lecithins such as egg yolk lecithin and soybean lecithin, hydrogenated lecithins in which unsaturated hydrocarbons in natural lecithins such as hydrogenated egg yolk lecithin and hydrogenated soybean lecithin are stabilized as saturated hydrocarbons by hydrogenation, hydrogenated lecithins in which the concentration of a specific lecithin has been increased, and purified or synthetic compounds derived from natural lecithins such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidic acid, phosphatidylinositol, and phosphatidylglycerol. These phospholipids may be used singly or in combination of two or more.

[0034] Commercially available phospholipids may be used, such as Resinol S-10M (trade name, containing 55-65% phosphatidylcholine) and Resinol S-10E (trade name, containing 75-85% phosphatidylcholine) from Nikko Chemicals, Basis (registered trademark) LP-60HR (trade name, containing 65-75% phosphatidylcholine) from Nisshin Oillio, and Egg Yolk Lecithin PL100P (trade name, containing approximately 80% phosphatidylcholine) from Kewpie Corporation.

[0035] Phospholipids orient in aqueous solvents to form microparticles with sac-like membranes, the shape of which varies depending on the polarity of the colorant contained within.

[0036] When the colorant is a water-soluble colorant, a bilayer membrane, i.e., a liposome, is formed by associating phospholipids. The water-soluble colorant is encapsulated in the liposome as fine particles. In the liposome, the phospholipids form a first molecular membrane with their hydrophilic groups oriented on the inside, enveloping the water-soluble colorant, and their hydrophobic groups oriented on the outside. Furthermore, the hydrophobic groups of the phospholipids that form the second molecular membrane are oriented relative to the first molecular membrane, and the hydrophilic groups of the phospholipids in the second layer are oriented on the outside. As a result, the liposome of this embodiment encapsulates the water-soluble colorant, and the hydrophilic groups of the phospholipids in the second layer are oriented outward, making it possible to disperse the liposome as fine particles in an aqueous solvent.

[0037] Liposomes encapsulating a water-soluble colorant are produced, for example, by the following method. First, a solution is prepared by dissolving a phospholipid in an organic solvent. Examples of the organic solvent include methyl ethyl ketone, tetrahydrofuran, methanol, ethanol, propanol, butanol, and water-soluble polyols such as glycerin, ethylene glycol, propylene glycol, butylene glycol, dipropylene glycol, 1,3-butylene glycol, isoprene glycol, and 1,2-pentanediol. A lipid or carbohydrate having a steroid skeleton, as described below, may also be added. The type of organic solvent used is selected depending on the solubility of the phospholipid or lipid having a steroid skeleton used.

[0038] Next, the organic solvent is distilled off from the solution to prepare a phospholipid membrane. When a lipid having a steroid skeleton is used in combination, the membrane becomes a mixed membrane of multiple components. Separately, a water-soluble colorant is dissolved in pure water to prepare an aqueous solution of the water-soluble colorant. Next, the aqueous solution of the water-soluble colorant is gradually added to the membrane while stirring, and the mixture is heated to 65 to 75°C to prepare a dispersion.

[0039] Next, the dispersion is subjected to ultrasonic treatment using an ultrasonic homogenizer to reduce the particle size of the particles in the dispersion. Thereafter, a centrifugal separator is used to separate and recover the liposomes encapsulating the water-soluble colorant. The liposomes are then redispersed in an aqueous solvent to obtain a dispersion of fine particles encapsulating the water-soluble colorant.

[0040] When the colorant is a water-insoluble oil-soluble dye or disperse dye, a bilayer membrane formed by association of phospholipids, i.e., a liposome, is formed. The oil-soluble dye or disperse dye is encapsulated in the liposome, which is a fine particle, in a region where the hydrophobic groups of the first molecular membrane and the hydrophobic groups of the second molecular membrane are encapsulated. In this case, only an aqueous solvent such as water is present in the center of the liposome. As a result, the liposome of this embodiment encapsulates the oil-soluble dye or disperse dye, and the hydrophilic groups of the phospholipids in the second layer are oriented outward, making it possible for the liposome to be dispersed as fine particles in an aqueous solvent.

[0041] Microparticles encapsulating oil-soluble dyes or disperse dyes are produced, for example, by the following method. First, a phospholipid is dissolved in the organic solvent described above to prepare a solution. At this time, the oil-soluble dye or disperse dye is dissolved in the solution together with the phospholipid. At this time, a lipid having a steroid skeleton, a carbohydrate, or a cellulose derivative described below may be added. The type of organic solvent used is selected depending on the solubility of the phospholipid, lipid having a steroid skeleton, and oil-soluble dye or disperse dye used.

[0042] Next, the organic solvent is distilled off from the solution to produce a membrane containing a mixture of phospholipids and oil-soluble or disperse dyes, etc. Next, pure water is gradually added to the membrane while stirring and heating to 65 to 75°C to produce a dispersion.

[0043] Next, the dispersion is subjected to ultrasonic treatment using an ultrasonic homogenizer to reduce the particle size of the particles in the dispersion. Then, a centrifugal separator is used to separate and recover the fine particles containing the oil-soluble dye or disperse dye. The fine particles are then redispersed in an aqueous solvent to obtain a dispersion of fine particles containing the oil-soluble dye or disperse dye.

[0044] When the colorant is a water-insoluble pigment, a monolayer or trilayer microparticle of phospholipids is formed. The pigment is encapsulated in the bag-shaped microparticles. In the microparticles, the hydrophobic groups of the phospholipids are oriented on the inside of the pigment-enveloping surface, and the hydrophilic groups are oriented on the outside, forming a monolayer microparticle. Furthermore, the hydrophilic groups of the phospholipids that form the second molecular layer are oriented relative to the first molecular layer of the monomolecular film, and the hydrophobic groups are oriented on the outside. Furthermore, the hydrophobic groups of the phospholipids that form the third molecular layer are oriented relative to the second molecular layer, and the hydrophilic groups are oriented on the outside. Here, even when the water-insoluble colorant is an oil-soluble dye or disperse dye, the oil-soluble dye or disperse dye may be encapsulated in the center of the microparticle in the same manner as the pigment described above.

[0045] Thus, the microparticles of the monolayer or trilayer of phospholipids of this embodiment contain pigment or oil-soluble dye or disperse dye, and the hydrophilic group of phospholipids is oriented outward, so that they can be dispersed as microparticles in aqueous solvent.In particular, when the coloring material is water-insoluble, it is necessary to disperse the coloring material in water by using a dispersant or the like in order to be used in aqueous ink, but in this embodiment, the phospholipid can stably disperse the water-insoluble coloring material in water, which is preferable.

[0046] Microparticles encapsulating pigments, oil-soluble dyes, or disperse dyes are produced, for example, by the following method: First, a phospholipid, a pigment, oil-soluble dyes, or disperse dyes, and the polyol described above are mixed to form a composite. At this time, a lipid having a steroid skeleton, a cellulose derivative, or a carbohydrate may be added.

[0047] Next, the combined material is kneaded to a desired average particle size using a kneading device such as a mortar or a kneader to obtain a kneaded material. In the case of using a pigment, the pigment particles are pulverized and their surfaces are coated with the phospholipid.

[0048] Next, pure water is added to the kneaded product, and ultrasonic treatment is performed using an ultrasonic homogenizer. This results in a dispersion of fine particles containing pigments, oil-soluble dyes, or disperse dyes. The dispersion may also be concentrated using a centrifugal separator.

[0049] As described above, the ink containing the fine particles can improve the image quality and ink ejection stability of the printed matter to which the ink is applied. Specifically, the colorant is encapsulated in the phospholipid fine particles, which protects the colorant and alleviates the constraints imposed by the colorant's inherent molecular structure, thereby enhancing its properties. This improves the behavior of the colorant on the printing medium after the colorant is applied to the printing medium.

[0050] When the colorant is a water-soluble colorant, the water resistance of the ink applied to the recording medium is improved. Therefore, bleeding can be suppressed even when the recorded material is wetted with water. Furthermore, the water-soluble colorant is less likely to penetrate the recording medium and more likely to remain on the surface. This improves the color development of the recorded material. Furthermore, in the case of water-soluble colorants that are easily affected by the pH of the ink or the metal ions contained in the ink, the protection of the microparticles makes it easier for the original color of the water-soluble colorant to be expressed. In other words, the image quality of the recorded material can be improved. In particular, when the microparticles are liposomes, the function of the microparticle membrane to protect the colorant is further enhanced, preventing discoloration of the recorded material and further improving the image quality of the recorded material. Furthermore, excellent dispersion stability in the ink also improves ejection stability.

[0051] When the colorant is a water-insoluble colorant, the dispersion stability of the fine particles in the ink is improved. As a result, the formation of foreign matter in the ink due to aggregation of the fine particles is less likely to occur, and the ejection stability of the ink can be improved. Furthermore, the occurrence of nozzle ejection failures in the inkjet head is suppressed, improving the image quality of the recorded material. Furthermore, the color development of the recorded material and the prevention of discoloration of the recorded material are also excellent.

[0052] In the ink, the average particle diameter D50 of the fine particles is preferably 50 nm or more and 350 nm or less, more preferably 60 nm or more and 300 nm or less, and even more preferably 80 nm or more and 250 nm or less. Furthermore, it is preferably 100 nm or more and 200 nm or less, and more preferably 130 nm or more and 180 nm or less. When the average particle diameter D50 of the fine particles is above the above range, the volume of the colorant encapsulated in the fine particles increases, improving the color development of the recorded material. When the average particle diameter D50 of the fine particles is below the above range, the ejection stability of the ink from the inkjet head is further improved.

[0053] The average particle diameter D50 refers to the 50% volume-based particle size distribution. The average particle diameter D50 of fine particles is measured by the dynamic light scattering method or laser diffraction method described in JIS Z8825. Specifically, a commercially available particle size distribution analyzer that uses the dynamic light scattering method as its measurement principle, such as Nikkiso's Microtrac UPA, is used.

[0054] In the ink, the mass ratio of the phospholipid content to the colorant content is preferably 0.5 to 8.0, more preferably 1.0 to 5.0, even more preferably 1.5 to 4.0, and particularly preferably 2.0 to 3.0.

[0055] 1.4.Lipids with a steroid skeleton The ink preferably contains a lipid having a steroid skeleton. The lipid having a steroid skeleton has the function of filling gaps in the membrane of the fine particles formed by the phospholipid. As a result, the membrane of the fine particles has a dense structure. By protecting the colorant with a denser membrane, the occurrence of bleeding in the recorded material is further suppressed for water-soluble colorants, and the dispersion stability of the fine particles in the water-insoluble colorant is further improved. In addition, interaction with metal ions in the inkjet ink composition is further suppressed, further suppressing discoloration of images in the recorded material.

[0056] To fill the gaps in the membrane of the fine particles, it is preferable to use a lipid other than a phospholipid, and it is more preferable to use a lipid having a steroid skeleton.

[0057] Examples of lipids having a steroid skeleton include animal-based lipids such as cholesterol, cholestanol, and 7-dehydrocholesterol, plant-based lipids such as α-sitosterol, β-sitosterol, γ-sitosterol, stigmasterol, fucosterol, spinasterol, and brassicasterol, hydrogenated plant cholesterols such as phytostanol, and mycelial lipids such as ergosterol.

[0058] In the ink, the mass ratio of the phospholipid content to the lipid having a steroid skeleton is preferably 0.5 to 8.0, more preferably 1.0 to 5.0. Furthermore, 1.5 to 3.0 is more preferable. When the mass ratio is above the above range, the lipid having a steroid skeleton has the ability to fill the gaps in the membranes of the microparticles formed by the phospholipids. When the mass ratio is below the above range, the lipid having a steroid skeleton that is released from the microparticles without filling the gaps in the membranes of the microparticles is reduced. This improves the ejection stability of the ink from the inkjet head.

[0059] 1.5. Cellulose Derivatives The ink preferably contains a cellulose derivative. The cellulose derivative has the function of filling gaps in the film of fine particles formed by phospholipids. This results in a dense film of the fine particles. By protecting the colorant with a denser film, bleeding in recorded materials is further suppressed for water-soluble colorants, and dispersion stability of fine particles in water-insoluble colorants is further improved. Furthermore, interaction with metal ions in the inkjet ink composition is suppressed, thereby suppressing discoloration of images in recorded materials.

[0060] Examples of cellulose derivatives include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose.

[0061] In the ink, the mass ratio of the phospholipid content to the cellulose derivative content is preferably 0.5 to 8.0, more preferably 1 to 5.0. Furthermore, 1.5 to 3.0 is more preferable. When the mass ratio is above the above range, the function of the cellulose derivative to protect the fine particles is further improved. When the mass ratio is below the above range, the amount of cellulose derivative that is not adsorbed to the surface of the fine particles but is liberated from the fine particles is reduced. Therefore, the ejection stability of the ink from the inkjet head is further improved.

[0062] 1.6.Carbohydrates The ink preferably contains a sugar. The sugar coats the surface of the fine particles and acts as a protective colloid. This makes the fine particles less likely to aggregate in the ink, improving the dispersion stability of the fine particles. This makes it less likely for aggregates to form in the ink, further improving the ejection stability of the ink from the inkjet head.

[0063] Examples of carbohydrates include trisaccharides or higher sugars such as raffinose, stachyose, dextrin, starch, and cellulose; monosaccharide sugar alcohols such as erythritol, xylitol, sorbitol, and mannitol; disaccharide sugar alcohols such as reduced maltose syrup, reduced starch syrup, and lactitol; artificial sweeteners such as saccharin, sucralose, aspartame, acesulfame potassium, and neotame; natural sweeteners such as stevia and glycyrrhizin; monosaccharides such as glucose, fructose, and galactose; and disaccharides such as maltose and sucrose.

[0064] In the ink, the mass ratio of the phospholipid content to the carbohydrate content is preferably 0.5 or more and 5.0 or less. It is further preferably 1.0 or more and 4.0 or less, and more preferably 2.0 or more and 3.0 or less. When the mass ratio is 0.5 or more, the dispersion stability of the microparticles is further improved. When the mass ratio is 5.0 or less, the amount of carbohydrate that is liberated from the microparticles without coating their surfaces is reduced. Therefore, the ejection stability from the inkjet head is further improved.

[0065] 1.7. Organic Solvents The ink may contain an organic solvent. By including an organic solvent, it is possible to control the ink's physical properties, such as viscosity and surface tension, as well as its behavior, such as drying and penetration, when applied to a recording medium. Examples of organic solvents include 2-pyrrolidones, 1,2-alkanediols, polyhydric alcohols, and glycol ethers. One or more of these may be used.

[0066] 2-Pyrrolidones suppress an increase in ink viscosity and improve the ejection stability of ink from an inkjet head. 2-Pyrrolidones refer to compounds having a 2-pyrrolidone skeleton. Examples of 2-pyrrolidones include unsubstituted 2-pyrrolidone as well as substituted 2-pyrrolidones such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-vinyl-2-pyrrolidone. The substituent on the 2-pyrrolidone skeleton is preferably an organic group such as a saturated or unsaturated hydrocarbon group having 1 to 5 carbon atoms.

[0067] 1,2-alkanediols are excellent at increasing the wettability of ink to a recording medium and wetting it uniformly. Examples of 1,2-alkanediols include 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol. Among 1,2-alkanediols, 1,2-alkanediols with an alkane having 5 or more carbon atoms are preferred.

[0068] Polyhydric alcohols prevent ink from drying out in the nozzles of an inkjet head, thereby reducing nozzle clogging and ink ejection problems. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,3-pentanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, trimethylolpropane, and glycerin. Among the polyhydric alcohols, polyhydric alcohols of alkanes having 4 or less carbon atoms and condensates in which hydroxyl groups of polyhydric alcohols of alkanes having 4 or less carbon atoms are condensed intermolecularly are preferred.

[0069] Glycol ethers adjust the wettability and penetration speed of the ink into the recording medium, thereby making the images and patterns on the recorded matter clearer. Examples of glycol ethers include alkylene glycol monoethers and alkylene glycol diethers.

[0070] Examples of alkylene glycol monoethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monoethyl ether.

[0071] Examples of alkylene glycol diethers include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether.

[0072] When an organic solvent is contained in the ink, its content is not particularly limited, but is preferably 5% by mass to 40% by mass, more preferably 7% by mass to 20% by mass, relative to the total mass of the ink.

[0073] 1.8.Other Ingredients The ink may contain other components such as a surfactant and a chelating agent.

[0074] Surfactants reduce the surface tension of the ink and improve the wetting of the ink onto a recording medium. Examples of surfactants include acetylene glycol surfactants, silicone surfactants, and fluorine surfactants.

[0075] Examples of acetylene glycol surfactants include Surfynol (registered trademark) 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, and DF110D (all trade names) manufactured by Air Products and Chemicals, Inc., and Olfine (registered trademark) B, Y, and P manufactured by Nissin Chemical Industry Co., Ltd. , 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 trade names), and Kawaken Fine Chemicals' Acetylenol (registered trademark) E00, E00P, E40, E100 (all trade names).

[0076] The silicone surfactant is not particularly limited, but a polysiloxane compound is used, such as a polyether-modified organosiloxane. Commercially available polyether-modified organosiloxanes include, for example, BYK (registered trademark)-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, and BYK-348 (all trade names) manufactured by BYK Japan, and 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, and KF-6017 (all trade names) manufactured by Shin-Etsu Chemical Co., Ltd.

[0077] As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, for example, BYK-340 (trade name) manufactured by BYK Japan Co., Ltd.

[0078] When a surfactant is contained in the ink, the content is not particularly limited, but is preferably 0.01% by mass or more and 2.00% by mass or less relative to the total mass of the ink.

[0079] The chelating agent complexes metal ions present in the ink through its chelating effect, preventing the precipitation of metal salts, which can lead to problems such as clogging of the inkjet head nozzles.

[0080] Examples of chelating agents include ethylenediaminetetraacetic acid (EDTA), sodium picolinate, potassium quinolinate, tetrasodium 3-hydroxy-2,2'-iminodisuccinate, methylglycine diacetate (MGDA), L-glutamic acid diacetate (GLDA), L-aspartic acid diacetate (ASDA), hydroxyethyliminodiacetic acid (HIDA), 3-hydroxy-2,2'-iminodisuccinic acid (HIDS), dicarboxymethylglutamic acid (CMGA), (S,S)-ethylenediaminedisuccinic acid (EDDS), and salts thereof. Examples of salts of the above chelating agents include metal salts such as sodium, potassium, and lithium, as well as ammonium and amine salts.

[0081] When a chelating agent is contained in the ink, the content is not particularly limited, but is preferably 0.01% by mass or more and 2.00% by mass or less relative to the total mass of the ink.

[0082] In addition to the above-mentioned components, the ink may contain various additives such as a resin emulsion, a preservative, an antifungal agent, an antioxidant, a pH adjuster, etc. Known additives can be used as these additives.

[0083] 2. Ink preparation method To prepare the ink, a dispersion of fine particles is prepared by the method described above, and then the above components are mixed in any order. Then, filtration or other methods are performed as necessary to remove impurities and foreign matter. The components are mixed by sequentially adding the materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer, and stirring and mixing them. Known methods such as centrifugal filtration and filter filtration can be used as the filtration method.

[0084] 3. Ink properties The surface tension of the ink at 25°C is preferably 10 mN / m or more and 40 mN / m or less, and more preferably 20 mN / m or more and 40 mN / m or less. This improves the ejection stability of the ink from the inkjet head. It also enables high-resolution images to be formed on the recording medium. The surface tension of the ink can be measured using an automatic surface tensiometer CBVP-Z manufactured by Kyowa Interface Science Co., Ltd.

[0085] From the same perspective as surface tension, the viscosity of the ink at 20°C is preferably 2 mPa·s (millipascal seconds) or more and 15 mPa·s or less, and more preferably 2 mPa·s or more and 5 mPa·s or less. Ink viscosity can be measured using a Pysica MCR-300 viscoelasticity tester. Specifically, the viscosity of the ink at 20°C can be determined by adjusting the ink temperature to 20°C, increasing the shear rate from 10 to 1000, and reading the viscosity at a shear rate of 200.

[0086] 4. Inkjet recording device A recording apparatus equipped with an inkjet head used in the recording method of this embodiment will now be described. Known devices such as inkjet printers can be used as the recording apparatus, and specific examples include on-carriage or off-carriage serial printers and line head printers.

[0087] An inkjet head ejects ink droplets to deposit them on a recording medium. The inkjet head has an actuator as a driving means. Examples of actuators include piezoelectric elements that utilize the deformation of a piezoelectric body, electromechanical conversion elements that utilize the displacement of a vibration plate due to electrostatic adsorption, and electrothermal conversion elements that utilize bubbles generated by heating. In this embodiment, a recording device having an inkjet head equipped with a piezoelectric element is used.

[0088] 5. Recording Media The recording medium is appropriately selected depending on the application and the type of ink. Examples of the recording medium include permeable recording media such as plain paper such as electrophotographic paper, inkjet paper, art paper, coated paper, and cast paper; fabrics made from natural or chemical fibers; and non-permeable recording media such as resin films and plates made from polyvinyl chloride, polyethylene, polypropylene, and polyethylene terephthalate; metal or alloy plates made from iron, silver, copper, aluminum, and other metals; inorganic plates made from glass and ceramic; and resin films having a thin film of an inorganic material, including a metal, formed on the surface. The ink of this embodiment is an aqueous ink, and is therefore suitable for use with the above-mentioned permeable recording media. The recording medium may be in the form of, for example, a roll, a single sheet, or a piece cut to a predetermined shape.

[0089] 6. Recording method The recording method according to this embodiment includes an application step in which the ink of this embodiment is ejected from an inkjet head and adhered to a recording medium using the above-described recording apparatus.

[0090] In the coating process, ink droplets are applied to a recording medium from the inkjet head of the recording device. At this time, the ink droplets are deposited at a predetermined position on the recording medium with a predetermined mass. In this way, the ink droplets are applied to the recording medium to form a desired image, character, pattern, color, or other design.

[0091] The recording method may include a drying step after the coating step. In the drying step, the ink attached to the recording medium is dried to evaporate volatile components such as water and organic solvents. Drying methods include, for example, leaving the ink to stand, or using a heat source such as wind or infrared rays. A recorded product is produced in this manner.

[0092] The recording method of this embodiment employs the ink described above, which improves the image quality of recorded material. In addition, the ink ejection stability from the inkjet head is improved, which results in excellent productivity of recorded material.

[0093] 7. Recordings As described above, the recorded matter according to this embodiment is formed by applying ink to a recording medium using a recording method. Recorded matter also includes those that have undergone post-processing such as trimming, lamination, bookbinding, and eyeleting. This makes it possible to provide recorded matter with improved image quality, including less bleeding and color development.

[0094] 8. Examples and Comparative Examples The effects of the present invention will be explained in more detail below with reference to examples and comparative examples. Examples 1 to 20 and comparative examples 1 to 4 are examples using water-soluble colorants. Hereinafter, these examples will also be referred to as examples and comparative examples of water-soluble colorants. Examples 21 to 50 and comparative examples 5 to 12 are examples using water-insoluble colorants. Hereinafter, these examples will also be referred to as examples and comparative examples of water-insoluble colorants.

[0095] The compositions and specifications of the inks of the examples and comparative examples of water-soluble colorants are shown in Tables 1 and 2, and the evaluation results are shown in Tables 3 and 4. The compositions and specifications of the inks of the examples and comparative examples of water-insoluble colorants are shown in Tables 5 to 7, and the evaluation results are shown in Tables 8 to 11. In the composition columns of Tables 1, 2, 5, 6, and 7, the units of values ​​are mass %, and columns with no value or - notation indicate that the component is not contained. Abbreviations are used for the names of some components. Abbreviations will be explained later.

[0096] Hereinafter, the inks of Example 1 to Example 50 will be collectively referred to as "inks of the Examples," the inks of Comparative Example 1 to Comparative Example 12 will be collectively referred to as "inks of the Comparative Examples," and the inks of Examples and Comparative Examples will be collectively referred to simply as "ink." Note that the present invention is not limited in any way by the following examples.

[0097] 8.1. Ink preparation Each ink was prepared according to the composition shown in Tables 1, 2, and 4 to 6. For inks using phospholipids, a dispersion of fine particles in which a colorant is encapsulated in phospholipids was first prepared by the method described above, and then the ink was prepared.

[0098] For inks that did not use phospholipids (Comparative Examples 1 to 3, 5 to 8), the inks were prepared directly without carrying out the step of preparing a dispersion. That is, the inks were prepared by mixing the components shown in the table. In Comparative Examples 4, 9 to 12, phospholipids were used, but the step of preparing a dispersion in which the phospholipids encapsulate a colorant was not carried out. That is, the inks were prepared by mixing the components shown in the table. The inks did not contain a dispersion in which the phospholipids encapsulate a colorant.

[0099] [Table 1]

[0100] [Table 2]

[0101] [Table 3]

[0102] [Table 4]

[0103] [Table 5]

[0104] The abbreviations and component details used in Tables 1, 2, and 4 to 6 are as follows:

[0105] water soluble dye Tin solvent for cochineal dye: sodium stannate trihydrate. Fujifilm Wako Pure Chemical Industries, Ltd. Cochineal dye: Carmine Red. Kiriya Chemical Co., Ltd. Gardenia yellow pigment: Xylin L-150. Kiriya Chemical Co., Ltd. Gardenia blue pigment: Kiriyas Blue-EL. Kiriya Chemical Co., Ltd. Water-insoluble colorant S-205 (Leuco dye): BD628675. BLD Pharmatech. Bisphenol A (leuco dye developer): Fujifilm Wako Pure Chemical Industries, Ltd. Lac pigment: Lac pigment powder. Kiriya Chemical Co., Ltd. Turmeric pigment: Turmeric pigment powder. Kiriya Chemical Co., Ltd. Indian indigo: Indian indigo powder. Aiguma Dye Co., Ltd. Binchotan: Binchotan fine powder. Kiriya Chemical Co., Ltd. phospholipids Phosphatidylcholine (lecithin): Soybean lecithin powder. Nacalai Tesque. Phosphatidylcholine (hydrogenated): Resinol S-10M. Nikko Chemicals. lipids with a steroid skeleton · Cholesterol: Fujifilm Wako Pure Chemical Industries, Ltd. β-Sitosterol: Fujifilm Wako Pure Chemical Industries, Ltd. Lipids (without steroid skeleton) · Triacylglycerol: Fujifilm Wako Pure Chemical Industries, Ltd. cellulose derivatives Methylcellulose: Metrose® SM-15. Shin-Etsu Chemical Co., Ltd. Carbohydrates Dextrin: Fujifilm Wako Pure Chemical Industries, Ltd. surfactants Olfine (registered trademark) E1010: Shin-Etsu Chemical Co., Ltd.

[0106] Evaluation The following evaluations were carried out for each ink, and the evaluation results are shown in Tables 3, 4, and 8 to 11. Note that bleeding of recorded material was only measured for inks containing water-soluble coloring materials.

[0107] 8.2.1. Creation of Records Using each ink, a recorded material for evaluation was prepared according to the following procedure. The ink was filled into an ink cartridge of a Seiko Epson inkjet printer PX-S840, and the ink cartridge was installed in the PX-S840. Next, a solid pattern with 100% ink deposition duty was printed on Fuji Xerox V-paper A4 as the plain paper recording medium to prepare a recorded material. The image resolution was 1440 x 720 dpi (dots per inch). %Duty refers to the number of recorded dots per square inch / (1440 x 720) x 100.

[0108] 8.2.2. Evaluation of bleeding The following method was used to evaluate bleeding of the recorded material. A recorded material that had been left for 30 minutes after printing was placed on a horizontal surface. Then, 0.5 mL of pure water was dropped onto the solid printed area of ​​the recorded material using a dropper. Immediately after that, one edge of a glass slide was pressed against the area near the water droplet on the recorded material, and the glass slide was slid approximately 15 cm over the recorded material to move the water droplet in one direction. The sliding speed of the glass slide was 15 cm for approximately 2 seconds. The boundary of the area where the water droplet had moved was then visually observed, and the state of bleeding was evaluated according to the following criteria. Evaluation criteria A: No bleeding is observed at the borders. B: There are one or two spots of bleeding at the border. C: There are 3 to 4 spots of bleeding at the border. D: There are five or more spots of bleeding at the border.

[0109] 8.2.3. Evaluation of color development The OD (Optical Density) value was measured as an index of the color development of the recorded material. Using an X-Rite i1 colorimeter (trade name), the OD value of the solid printed area of ​​the recorded material was measured under the measurement conditions of no light source filter, light source D50, and a viewing angle of 2 degrees, and evaluated according to the following criteria. Note that the measurement was performed at least 5 minutes after recording. The AA:OD value is 1.0 or greater. A: The OD value is 0.8 or more and less than 1.0. B: The OD value is 0.6 or more and less than 0.8. C:OD value is less than 0.6.

[0110] 8.2.4. Evaluation of discoloration The following method was used to evaluate discoloration of the printed matter. Two printed matters were produced with a one-minute time difference using the method described above. The change in color tone of the printed matter immediately after printing and the printed matter one minute after printing was visually observed, and evaluated according to the following criteria. A: No change in color is observed. B: A slight change in color is observed. C: A clear change in color is observed.

[0111] 8.2.5. Evaluation of Discharge Stability To evaluate the ink ejection stability of the inkjet head, 50 sheets of recorded material were continuously produced using the above-mentioned method for producing recorded material, and the initial and subsequent nozzle states were confirmed. Specifically, a nozzle check pattern was first printed to confirm that all nozzles were ejecting normally. Next, 50 solid-printed recorded material were continuously produced. Immediately after this, a nozzle check pattern was printed again. The number of nozzles that were unable to eject ink was counted using the nozzle check pattern, and the results were evaluated according to the following criteria. AA: The number of nozzles that cannot eject ink is four or less. A: The number of nozzles that cannot eject is between 5 and 9. B: The number of nozzles that cannot be protruded is 10 or more and 19 or less. C: The number of nozzles that cannot eject is 20 or more.

[0112] [Table 6]

[0113] [Table 7]

[0114] [Table 8]

[0115] [Table 9]

[0116] [Table 10]

[0117] [Table 11]

[0118] 8.3. Summary of evaluation results 8.3.1.Water-soluble colorants As shown in Tables 3 and 4, in the examples using water-soluble coloring materials, the bleeding evaluation results were C or higher at all levels from Example 1 to Example 20. In particular, among Examples 1 to 18, Examples 9 and 18 were rated B, and the others were rated A. This shows that the examples using water-soluble coloring materials improve bleeding in recorded materials.

[0119] In the evaluation of color development, Examples 1 to 19 were rated B or higher. In particular, all examples except Examples 5, 15, and 19 were rated A or higher, and Examples 1 to 4, Examples 6 to 9, and Examples 11, 13, and 14 were rated AA. This demonstrates that the examples using water-soluble colorants improve the color development of recorded materials.

[0120] In the discoloration evaluation, Examples 1 to 19 were rated B or higher. In particular, Examples 1 to 18 were rated A or higher. This indicates that the examples using water-soluble coloring materials make recorded matter less susceptible to discoloration.

[0121] In the evaluation of ejection stability, Examples 1 to 18 were rated B or higher. In particular, all examples except Examples 15, 16, and 17 were rated A or higher. This demonstrates that the ejection stability of the ink is improved in the examples using water-soluble coloring materials.

[0122] In contrast, in all comparative examples using water-soluble coloring materials, the evaluation results for bleeding were graded D, indicating that bleeding is likely to occur in printed matter. Also, in comparative examples 3 and 4, the evaluation results for color development, color change, and ejection stability were all graded C, indicating that it is difficult to improve these properties.

[0123] 8.3.2. Water-insoluble colorants As shown in Tables 8 to 10, in the Examples using water-insoluble colorants, the evaluation results for color development were B or higher at all levels from Example 21 to Example 50. In particular, all examples except Examples 24, 25, and 30 were rated A or higher. This demonstrates that the Examples using water-insoluble colorants improve the color development of recorded materials.

[0124] In the discoloration evaluation, all levels of Examples 21 to 50 were rated B or higher. In particular, all levels except for Examples 24, 25, and 30 were rated A. This demonstrates that the examples using water-insoluble colorants make recorded materials less susceptible to discoloration.

[0125] In the evaluation of ejection stability, Examples 21 to 50 were rated B or higher. In particular, all examples except Examples 24, 25, 30, 42, 46, and 50 were rated A or higher. This demonstrates that the ejection stability of inks in the examples using water-insoluble colorants is improved.

[0126] In contrast, as shown in Table 11, in all the comparative examples using water-insoluble colorants, the evaluation results for color development were B or lower, indicating that it is difficult to improve the color development of recorded matter. In addition, in all the comparative examples using water-insoluble colorants, the evaluation results for discoloration were B or lower, indicating that discoloration of recorded matter is likely to occur. Furthermore, in all the comparative examples using water-insoluble colorants, the ink ejection stability was rated C, indicating that the ejection stability was inferior to that of the examples using water-insoluble colorants.

Claims

1. Water, a phospholipid that forms a microparticle; a colorant encapsulated in the fine particles; An inkjet ink composition comprising a cellulose derivative.

2. Water, a phospholipid that forms a microparticle; a colorant encapsulated in the fine particles; An inkjet ink composition comprising:

3. The mass ratio of the content of the phospholipid to the content of the cellulose derivative is 1 or more and 5 or less. The ink-jet ink composition of claim 1 , wherein:

4. The mass ratio of the content of the phospholipid to the content of the carbohydrate is 0.5 or more and 5.0 or less. The ink-jet ink composition of claim 2 .

5. 5. The ink composition according to claim 1, wherein the coloring material is either a water-soluble coloring material or a water-insoluble coloring material.

10. The ink-jet ink composition according to any one of claims 1 to 9.

6. the water-soluble coloring material is a water-soluble dye derived from an animal or a plant, The water-insoluble coloring material is a water-insoluble coloring material derived from an animal or a plant, and is an oil-soluble dye or 6. The ink-jet ink composition of claim 5, wherein the ink is a pigment.

7. The coloring material includes the water-soluble coloring material, The ink-jet printer according to claim 6, wherein the water-soluble dye forms a chelate complex. composition.

8. The composition according to any one of claims 1 to 7, comprising a lipid having a steroid skeleton.

1. An inkjet ink composition comprising:

9. The mass ratio of the content of the phospholipid to the content of the lipid having a steroid skeleton is The ink-jet ink composition of claim 8 , wherein the ρ is 1 or greater and 5 or less.

10. The microparticles according to any one of claims 1 to 9, wherein the microparticles are bilayer membranes in which the phospholipids are associated.

2. The ink-jet ink composition according to claim 1.

11. The average particle diameter D50 of the fine particles is 80 nm or more and 250 nm or less. The ink-jet ink composition of claim 10.

12. The ink-jet ink composition according to any one of claims 1 to 11 is A recording method comprising a step of ejecting ink from a jet head and depositing it on a recording medium.

13. The ink-jet ink composition according to any one of claims 1 to 11 is a recording medium. A recording that is attached to the body.

Images