Ink-jet recording method and printed matter

Abstract

To provide a technique for forming an image having excellent scratch resistance and glossiness.SOLUTION: An ink-jet recording method comprises the following steps of: discharging ink onto the surface of a medium in a first condition; and heating the medium to dry the ink in a second condition. The first condition includes (1) using ink that contains resin particles with Tg of 50°C or higher, an organic solvent, and water, the ink also containing 5 to 11 mass% of resin particles. According to the first condition and the second condition, the following conditions are satisfied: (2) when the ratio of an ink discharge amount in the discharging step to a residual ink amount in the drying step is between 1:0.05 and 1:0.15, 80% or more of a plurality of second partial regions randomly selected from an ink-adhered region on the surface of the medium, exhibit a developed surface area ratio Sdr of 6% or less when the ink discharge amount is 1 mg / cm2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This specification discloses an inkjet recording method for ejecting ink onto the surface of a medium, and a technique relating to printed matter. [Background technology]

[0002] Patent Document 1 discloses a technique for recording an image on coated paper, which is a low-absorbency medium, using ink containing resin particles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2014-008639 Summary of the Invention [Problem to be solved by the invention]

[0004] This specification provides a technique for realizing a printed matter having excellent abrasion resistance and glossiness when printing is performed on a low-absorbency medium by an inkjet recording method. [Means for solving the problem]

[0005] This specification discloses an inkjet recording method. The inkjet recording method includes a discharging step of discharging ink onto the surface of a medium under first conditions, and a drying step of heating the medium under second conditions after the discharging step to dry the ink. At least 80% of a plurality of first partial regions randomly selected from the surface of the medium have an arithmetic mean height Sa1 of 5 nm or less. The first condition includes (1) using an ink containing resin particles having a glass transition temperature Tg of 50°C or higher, an organic solvent, and water, wherein the ink contains 5% to 11% by mass of the resin particles. The first condition and the second condition are: (2) when the ratio of the ejection amount of the ink in the ejection step to the remaining amount of the ink in the drying step is 1:0.05 to 0.15, the ejection amount of the ink in the ejection step is 1 mg / cm in 80% or more of a plurality of second partial areas randomly selected from the adhesion area on the surface of the medium to which the ink is adhered. 2 The condition to be met is that the development area ratio Sdr is 6% or less.

[0006] This inkjet recording method forms a coating film with a relatively low developed area ratio, which makes it possible to realize printed matter with excellent abrasion resistance and gloss.

[0007] A printed matter obtained by ejecting ink onto the surface of a medium is also novel and useful. The printed matter has the following characteristics: (1) an arithmetic mean height Sa1 of 5 nm or less in 80% or more of a plurality of first partial regions randomly selected from the non-ink-attached regions on the surface of the medium, and (2) an ejection amount of the ink of 1 mg / cm or less in 80% or more of a plurality of second partial regions randomly selected from the ink-attached regions on the surface of the medium. 2 The deployed area ratio Sdr is 6% or less. [Brief explanation of the drawings]

[0008] [Figure 1] 1 shows the configuration of an image recording device 10. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Configuration of image recording device 10) An image recording device 10 according to an embodiment will be described with reference to the drawings. The image recording device 10 is a device that ejects ink toward a sheet 2 according to an inkjet recording method to record an image on the sheet 2. The image recording device 10 is used by being placed on a table. However, in other embodiments, the image recording device 10 may be used by being placed on the floor or on a rack, and may be small or large.

[0010] As shown in FIG. 1, the image forming apparatus 10 includes a housing 12, a first holder 14, a second holder 16, a first tensioner 18, a second tensioner 20, two first conveyor roller pairs 22, two second conveyor roller pairs 24, two third conveyor roller pairs 26, and a control unit 28. The control unit 28 is communicatively connected to each component of the image recording apparatus 10 and controls the operation of each component. Note that each component does not necessarily have to be located in the position shown in the figure. Furthermore, some of the components (e.g., the second holder 16) may be located outside the housing 12.

[0011] The first holder 14 supports the first roll 4 on which the sheet 2 is wound in a roll shape. Here, the sheet 2 is a long sheet. The first holder 14 is rotated by a conveyance motor (not shown). As the first holder 14 rotates, the first roll 4 supported by the first holder 14 also rotates.

[0012] The first tensioner 18 is disposed above the first holder 14. The first tensioner 18 has an outer peripheral surface 18a against which the sheet 2 abuts. The sheet 2 pulled out from the roll 4 curves along the outer peripheral surface 18a and is fed laterally (particularly to the right in FIG. 1).

[0013] Each of the two first conveying roller pairs 22 includes a first conveying roller 22a and a first pinch roller 22b. The first conveying roller 22a comes into contact with the first pinch roller 22b to form a nip 8. The nip 8 is disposed at a position approximately equal to the upper end of the outer peripheral surface 18a of the first tensioner 18 in the vertical direction. Each of the two first conveying roller pairs 22 is rotated by a conveying motor (not shown). Each of the two first conveying roller pairs 22 rotates while nipping the sheet 2, thereby conveying the sheet 2 sent out from the first tensioner 18 downstream. The number and arrangement of the first conveying roller pairs 22 are not particularly limited.

[0014] Each of the two second conveying roller pairs 24 includes a second conveying roller 24a and a second pinch roller 24b. The second conveying roller 24a comes into contact with the second pinch roller 24b to form a nip 8. The nip 8 is disposed at a position approximately equal to the upper end of the outer peripheral surface 20a of the second tensioner 20 in the vertical direction. Each of the two second conveying roller pairs 24 is rotated by a conveying motor (not shown). Each of the two second conveying roller pairs 24 rotates while nipping the sheet 2, thereby conveying the sheet 2 downstream. The number and arrangement of the second conveying roller pairs 24 are not particularly limited.

[0015] Each of the two third conveying roller pairs 26 includes a third conveying roller 26a and a third pinch roller 26b. The third conveying roller 26a comes into contact with the third pinch roller 26b to form a nip 8. The nip 8 is disposed at a position generally equal to the upper end of the outer circumferential surface 18a of the first tensioner 18 in the vertical direction. Each of the two third conveying roller pairs 26 is rotated by a conveying motor (not shown). Each of the two third conveying roller pairs 26 rotates while nipping the sheet 2, thereby conveying the sheet 2 to the second tensioner 20. The number and arrangement of the third conveying roller pairs 26 are not particularly limited.

[0016] The second tensioner 20 is disposed above the second holder 16. The second tensioner 20 has an outer peripheral surface 20a that contacts the sheet 2. The sheet 2 conveyed by the third conveying roller pair 26 curves along the outer peripheral surface 20a and is sent out downward.

[0017] The second holder 16 supports the second roll 6. The second holder 16 is rotated by a conveyance motor (not shown). As the second holder 16 rotates, the second roll 6 supported by the second holder 16 also rotates, and the sheet 2 on which the image is formed is wound up into a roll.

[0018] A conveying path 100 along which the sheet 2 is conveyed is formed between the first holder 14 and the second holder 16. When the sheet 2 passes through this conveying path 100, an image is recorded on the sheet 2.

[0019] As shown in FIG. 1, the image forming apparatus 10 further includes a surface treatment device 30, a head 32, and a drying device .

[0020] The surface processing device 30 is disposed above the conveying path 100. The surface processing device 30 is a device that performs surface processing on the sheet 2. In this embodiment, the surface processing device 30 performs surface processing on the surface of the sheet 2 (i.e., the printing surface, which is the upper surface in Figure 1) by corona discharge. When this surface processing is performed, the surface tension of the sheet 2 is improved, and the wettability of the surface of the sheet 2 is increased. This improves the adhesion of ink to the sheet 2. Note that the surface processing device 30 is not limited to the above device, and may be, for example, a device that irradiates plasma onto the sheet 2 to modify the surface of the sheet 2, thereby improving the wettability of the surface of the sheet 2.

[0021] The head 32 is disposed downstream of the surface treatment device 30. The head 32 includes a plurality of nozzles 33. When a piezoelectric element (not shown) corresponding to each nozzle 33 is driven, ink supplied from an ink tank (not shown) is ejected to the outside through each nozzle 33. In this manner, each nozzle 33 ejects ink toward the surface of the sheet 2 (i.e., the printing surface, which is the upper surface in FIG. 1), thereby forming an image on the surface of the sheet 2. Note that the number and arrangement of the nozzles 33 are not particularly limited.

[0022] The drying device 34 is disposed downstream of the head 32. The drying device 34 is, for example, a dryer, a heat gun, or an oven. The drying device 34 heats the surface of the sheet 2 (i.e., the printing surface, which is the upper surface in FIG. 1) and can dry the ink adhering to that surface.

[0023] (Sheet 2) The surface of the sheet 2 (i.e., the printing surface, which is the upper surface in FIG. 1 ) is characterized in that 80% or more of a plurality of (e.g., 10) randomly selected partial regions (e.g., 1 μm × 1 μm) have an arithmetic mean height Sa1 of 5 nm or less. That is, the sheet 2 has a relatively high surface smoothness and low absorption of liquids such as ink and treatment liquid, making it a so-called low-absorbency medium. Examples of materials for the sheet 2 that satisfy the above Sa1 include plastics such as polyvinyl chloride (PVC), polyethylene terephthalate (PET), polycarbonate, polystyrene, polyurethane, and polyethylene. The sheet 2 may be formed by coating a substrate such as paper with the above-mentioned plastics as long as it satisfies the above Sa1. While the above-mentioned materials generally satisfy the above Sa1, they may not necessarily satisfy the above Sa1 due to manufacturing errors or the like. Therefore, the technology disclosed herein can employ sheets whose printing surfaces are made of the above-mentioned materials that satisfy the above Sa1. Furthermore, the technology disclosed in this specification can also appropriately employ materials other than those mentioned above, as long as they satisfy the above Sa1.

[0024] (ink) The ink contains resin particles, a pigment, an organic solvent, and water. However, the ink does not necessarily contain a pigment. The ink is a water-based ink for inkjet recording in which the resin particles, the pigment, and the organic solvent are dissolved or dispersed in water.

[0025] (resin particles) Resin particles are blended to fix the solid content (e.g., pigments) in the ink to the surface of the medium, improving fixation. The resin particles melt during the drying process, and the molten resin particles bond together, forming a coating of resin particles on the surface of the medium when the ink dries.

[0026] The resin particles may contain, for example, at least one of methacrylic acid and acrylic acid as a monomer, and commercially available products may be used. The resin particles may further contain, for example, styrene, vinyl chloride, etc. as a monomer. The resin particles may be contained in, for example, an emulsion. The emulsion is composed of, for example, resin particles and a dispersion medium (e.g., water, etc.). The resin particles are not dissolved in the dispersion medium, but are dispersed in the dispersion medium within a specific particle size range. Examples of resin particles include acrylic acid-based resins, maleic acid-based ester resins, vinyl acetate-based resins, carbonate-based resins, polycarbonate-based resins, styrene-based resins, ethylene-based resins, polyethylene-based resins, propylene-based resins, polypropylene-based resins, urethane-based resins, polyurethane-based resins, polyester-based resins, and copolymer resins thereof. One type of resin particle may be used alone, or two or more types may be used in combination.

[0027] The resin particles used are those having a glass transition temperature (Tg) of 50°C or higher. The lower limit of the glass transition temperature (Tg) is, for example, 60°C or higher, for example, 65°C or higher, or for example, 70°C or higher. The upper limit of the glass transition temperature (Tg) is not particularly limited, but is, for example, 100°C or lower, for example, 90°C or lower, for example, 85°C or lower, or for example, 80°C or lower. The range of Tg can be set by appropriately combining the above upper and lower limits, but is, for example, 50°C or higher and 100°C or lower, for example, 60°C or higher and 90°C or lower, for example, 65°C or higher and 85°C or lower, or for example, 70°C or higher and 80°C or lower. A Tg of 50°C or higher can impart suitable robustness to the ink coating after drying, allowing the formation of an image with excellent abrasion resistance.

[0028] The emulsion may be, for example, a commercially available product, such as "Superflex (registered trademark) 870" (Tg: 78°C) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., "Mowinyl (registered trademark) 6969D" (Tg: 71°C) manufactured by Japan Coating Resins Co., Ltd., "Takelac (registered trademark) W-5661" (Tg: 70°C) manufactured by Mitsui Chemicals, Inc., "KT-8803" (Tg: 65°C) manufactured by Unitika Ltd., "Pesresin A-647GEX" (Tg: 60°C) manufactured by Takamatsu Oil & Fat Co., Ltd., and "Hi-Loss-X (registered trademark) KE-1062" (Tg: 112°C) and "Hi-Loss-X (registered trademark) QE-1042" (Tg: 69°C) manufactured by Seiko PMC Corporation.

[0029] The average particle diameter of the resin particles is not particularly limited, but is within a range of, for example, 5 nm to 500 nm, for example, 20 nm to 300 nm, or for example, 30 nm to 100 nm. The average particle diameter can be measured as an arithmetic mean diameter using, for example, a dynamic light scattering particle size distribution analyzer "LB-550" manufactured by Horiba, Ltd.

[0030] The resin particles are contained in the ink in an amount ranging from 5% to 11% by mass relative to the total amount of ink. The lower limit of the content is, for example, 5.5% by mass or more, for example, 6% by mass or more, for example, 6.5% by mass or more, or for example, 7% by mass or more. The upper limit of the content is, for example, 10.5% by mass or less, for example, 10% by mass or less, for example, 9.5% by mass or less, or for example, 9% by mass or less. The content range can be set by appropriately combining the above upper and lower limits, and is, for example, 5.5% by mass or more and 10.5% by mass or less, for example, 6% by mass or more and 10% by mass or less, for example, 6.5% by mass or more and 9.5% by mass or less, or for example, 7% by mass or more and 9% by mass or less. If the resin particle content is 5% by mass or more, the solid components (pigments, etc.) in the ink can be stably fixed to the surface of the medium, and if the resin particle content is 11% by mass or less, the gloss of the ink coating after drying and the storage stability of the ink can be improved.

[0031] (pigment) The pigment is not particularly limited and may include, for example, carbon black, inorganic pigments, and organic pigments. Examples of carbon black include furnace black, lamp black, acetylene black, and channel black. Examples of inorganic pigments include titanium oxide, iron oxide-based inorganic pigments, and carbon black-based inorganic pigments. Examples of organic pigments include azo pigments such as azo lake, insoluble azo pigment, condensed azo pigment, and chelate azo pigment; 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 lake pigments and acid dye lake pigments; nitro pigments (nitroso pigments); and aniline black daylight fluorescent pigments. Other pigments may also be used as long as they are dispersible in an aqueous phase. Specific examples of these pigments include CI Pigment Black 1, 6, and 7; CI Pigment Yellow 1, 2, 3, 12, 13, 14, 15, 16, 17, 55, 74, 78, 150, 151, 154, 180, 185, and 194; CI Pigment Orange 31 and 43; CI Pigment Red 2, 3, 5, 6, 7, 12, 15, 16, 48, 48:1, 53:1, 57, 57:1, 112, 122, 123, 124, 125, 126, 127, 128, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 185, and 186; Examples of pigments include CI Pigment Violet 19 and 196; CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 16, 22, and 60; CI Pigment Green 7 and 36; and solid solutions of these pigments. The ink may be prepared by dispersing the pigment in water with a dispersant. Examples of dispersants include common polymer dispersants (pigment dispersion resins, resin dispersants), and may be prepared in-house. In addition, the pigment in the ink may be encapsulated in a polymer.

[0032] A method for dispersing a pigment using a pigment dispersing resin includes, for example, dispersing the pigment using a dispersing device. The dispersing device used for dispersing the pigment is not particularly limited as long as it is a general dispersing machine, and examples thereof include a ball mill, a roll mill, and a sand mill (e.g., a high-speed type).

[0033] The pigment may be a self-dispersing pigment. Self-dispersing pigments are pigments that can be dispersed in water without the use of a dispersant, for example, by chemically bonding at least one hydrophilic functional group, such as a carbonyl group, a hydroxyl group, a carboxylic acid group, a sulfonic acid group, or a phosphate group, or a salt thereof, directly or via another group. Examples of self-dispersing pigments that can be used include pigments treated by methods described in JP-A-8-3498, JP-T-2000-513396, JP-T-2008-524400, JP-T-2009-515007, and JP-T-2011-515535. Both inorganic and organic pigments can be used as raw materials for self-dispersing pigments. Examples of pigments suitable for the above treatment include carbon blacks such as "MA8" and "MA100" manufactured by Mitsubishi Chemical Corporation. Commercially available self-dispersing pigments may also be used. Examples of 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" manufactured by Cabot Corporation; "BONJET (registered trademark) BLACK CW-2" and "BONJET (registered trademark) BLACK CW-3" manufactured by Orient Chemical Industry Co., Ltd.; and "LIOJET (registered trademark) WD BLACK 002C" manufactured by Toyo Ink Mfg. Co., Ltd.

[0034] One type of pigment may be used alone, or two or more types may be used in combination. The solid content of the pigment relative to the total amount of ink (pigment solid content amount) is not particularly limited and can be determined appropriately depending on the desired optical density or saturation, etc. The pigment solid content amount is, for example, 0.1% by mass or more and 20% by mass or less, for example, 1% by mass or more and 10% by mass or less, or for example, 2% by mass or more and 8% by mass or less. The pigment solid content amount is the mass of the pigment only, and does not include the mass of the resin dispersant, etc. (i.e., converted into the amount of active ingredients).

[0035] (organic solvent) The organic solvent is not particularly limited, and any organic solvent can be used. Examples of organic solvents include propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, ethylene glycol, 1,2-butanediol, propylene glycol monobutyl ether, dipropylene glycol monopropyl ether, triethylene glycol monobutyl ether, 1,2-hexanediol, and 1,6-hexanediol, as well as glycol ethers having a propylene oxide group. Other examples of organic solvents include alkyl alcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. Other examples include alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, and diethylene glycol. Other examples include lower alkyl ethers of alkylene glycols such as glycerin, ethylene glycol monomethyl (or ethyl, propyl, butyl) ether, diethylene glycol monomethyl (or ethyl, propyl, butyl) ether, triethylene glycol monomethyl (or ethyl, propyl, butyl, hexyl) ether, tetraethylene glycol monomethyl (or ethyl, propyl, butyl, hexyl) ether, propylene glycol monomethyl (or ethyl, propyl, butyl) ether, dipropylene glycol monomethyl (or ethyl, propyl, butyl) ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl (or ethyl, propyl, butyl) ether, and tetrapropylene glycol monomethyl (or ethyl) ether. Other examples include N-methyl-2-pyrrolidone, 2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone.

[0036] Among the organic solvents mentioned above, solvents with a vapor pressure of 150 Pa or less at 25°C are preferably used. If the vapor pressure is 150 Pa or less, the organic solvent evaporates at an appropriate rate when the ink dries, and the remaining organic solvent can promote melting of the resin. The molten resin particles spread substantially uniformly over the surface of the medium to form a film, making it possible to form a highly smooth coating film. However, solvents with a vapor pressure of more than 150 Pa at 25°C may also be used as the organic solvent.

[0037] The content of the organic solvent relative to the total amount of ink is not particularly limited. The lower limit of the content is, for example, 0.1% by mass or more, for example, 0.5% by mass or more, for example, 1% by mass or more, for example, 3% by mass or more, or for example, 5% by mass or more. The upper limit of the content is, for example, 30% by mass or less, for example, 20% by mass or less, for example, 15% by mass or less, for example, 10% by mass or less, or for example, 7% by mass or less. The range of the content can be set by appropriately combining the above upper and lower limits, and is, for example, 0.1% by mass or more and 30% by mass or less, for example, 0.5% by mass or more and 20% by mass or less, for example, 1% by mass or more and 15% by mass or less, for example, 3% by mass or more and 10% by mass or less, or for example, 5% by mass or more and 7% by mass or less.

[0038] (water) The water is preferably ion-exchanged water or pure water. The content of water relative to the total amount of ink is determined appropriately depending on the desired ink properties, etc. The content of water is, for example, in the range of 15% by mass to 95% by mass, or, for example, in the range of 25% by mass to 85% by mass. The content of water may be, for example, the balance of other components.

[0039] (Other ingredients) The ink may further contain a surfactant. The surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, a commercially available product may be used. Specific examples of the surfactant include silicone-based surfactants and acetylene-based surfactants. In particular, since silicone-based surfactants do not contain impurities such as ethylene oxide, the use of a silicone-based surfactant as the surfactant can further reduce the generation of VOCs (volatile organic compounds).

[0040] Examples of commercially available silicone surfactants include "Silface (registered trademark) SAG002," "Silface (registered trademark) SAG005," and "Silface (registered trademark) SAG503A," all manufactured by Nissin Chemical Industry Co., Ltd.

[0041] Commercially available acetylene surfactants include, for example, "Olfine (registered trademark) E1004," "Olfine (registered trademark) E1008," and "Olfine (registered trademark) E1010" manufactured by Nissin Chemical Industry Co., Ltd.; "Surfynol (registered trademark) 440," "Surfynol (registered trademark) 465," and "Surfynol (registered trademark) 485" manufactured by Air Products and Chemicals, Inc.; and "Acetylenol (registered trademark) E40" and "Acetylenol (registered trademark) E100" manufactured by Kawaken Fine Chemicals Co., Ltd.

[0042] The ink may contain other surfactants in addition to or instead of the silicone-based surfactant and the acetylene-based surfactant. Examples of other surfactants include nonionic surfactants manufactured by Kao Corporation such as the "EMULGEN (registered trademark)" series, "RHEODOL (registered trademark)" series, "EMASOL (registered trademark)" series, "EXCEL (registered trademark)" series, "EMANON (registered trademark)" series, "AMIET (registered trademark)" series, and "AMINON (registered trademark)" series; nonionic surfactants manufactured by Toho Chemical Industry Co., Ltd. such as the "SORBON (registered trademark)" series; nonionic surfactants manufactured by Lion Corporation such as the "DOBANOX (registered trademark)" series, "LEOCOL (registered trademark)" series, "LEOX (registered trademark)" series, "LAOL,LEOCOL (registered trademark)" series, "LIONOL (registered trademark)" series, "CADENAX (registered trademark)" series, "LIONON (registered trademark)" series, and "LEOFAT (registered trademark)" series; and anionic surfactants manufactured by Kao Corporation such as the "EMAL (registered trademark)" series, "LATEMUL (registered trademark)" series, "VENOL (registered trademark)" series, and "NEOPELEX (registered trademark)" series, NS SOAP, KS SOAP, OS SOAP and the "PELEX (registered trademark)" series, etc.; anionic surfactants manufactured by Lion Corporation such as the "LIPOLAN (registered trademark)" series, "LIPON (registered trademark)" series, "SUNNOL (registered trademark)" series, "LIPOTAC (registered trademark) TE, ENAGICOL" series, "LIPAL (registered trademark)" series, and "LOTAT (registered trademark)" series; and cationic surfactants manufactured by Daiichi Kogyo Seiyaku Co., Ltd. such as "Catiogen (registered trademark) ES-OW" and "Catiogen (registered trademark) ES-L".

[0043] The surfactant may be used alone or in combination of two or more. The content of the surfactant relative to the total amount of ink can be appropriately selected depending on the purpose. The content is, for example, 0.1% by mass to 5% by mass, for example, 0.5% by mass to 3.5% by mass, or for example, 1% by mass to 3% by mass.

[0044] The ink may further contain conventionally known additives as needed. Examples of additives include a pH adjuster, a viscosity adjuster, a surface tension adjuster, and an anti-mold agent. Examples of viscosity adjusters include polyvinyl alcohol, cellulose, and a water-soluble resin.

[0045] The ink can be prepared, for example, by uniformly mixing resin particles, a colorant, an organic solvent, water, and, if necessary, other additives using a conventionally known method, and then removing any insoluble matter using a filter or the like.

[0046] (Hansen solubility parameter distance between organic solvent and resin particles) The Hansen solubility parameter (HSP) distance between the organic solvent and resin particles described above will now be described. HSP is composed of the energy due to intermolecular dispersion forces, the energy due to intermolecular dipole interactions, and the energy due to intermolecular hydrogen bonds. The HSP is obtained as the vector sum of these three energies and is expressed by plotting it in a three-dimensional space (Hansen space) with the three parameters as its coordinate axes. The HSP of a substance can be obtained, for example, by referring to a publicly known database. Alternatively, the HSP can be calculated using software such as HSPiP. The HSP distance is the distance between the HSPs of two substances in the three-dimensional space. The smaller the HSP distance between two substances, the higher the compatibility. In this embodiment, the HSP distance between the organic solvent and the resin particles is preferably 1 to 5. A HSP distance of 1 to 5 ensures adequate compatibility between the organic solvent and the resin particles, ensuring ink storage stability and allowing the resin particles to form a suitable coating film. More preferably, the HSP distance may be 2 to 4. However, the HSP distance between the organic solvent and the resin particles is not particularly limited, and may be less than 1 or more than 5.

[0047] (Inkjet recording method) Next, an inkjet recording method using the image forming apparatus 10 will be described. The recording method includes a surface treatment process, a discharge process, a drying process, and a pressure application process. The control unit 28 executes each process in response to, for example, an external command to form an image input to the image forming apparatus 10. When the command is input, the control unit 28 controls each unit, such as the first conveying roller pair 22, the second conveying roller pair 24, and the third conveying roller pair 26, to convey the sheet 2 on the conveying path 100.

[0048] (Surface treatment process) In the surface treatment step, the control unit 28 performs surface treatment on the sheet 2. The control unit 28 controls the surface treatment device 30 to generate a corona discharge, and performs surface treatment on the sheet 2 by exposing the sheet 2 passing under the surface treatment device 30 to the corona discharge. This modifies the surface of the sheet 2, improving the wettability of the printing surface. Note that the surface treatment step does not necessarily have to be performed.

[0049] (Discharge process) In the ejection process, the control unit 28 ejects ink onto the surface of the sheet 2 being transported along the transport path 100. The control unit 28 controls piezo elements (not shown) and the like corresponding to the plurality of nozzles 33, thereby selectively ejecting ink from each nozzle 33 toward the sheet 2 passing below the head 32. In this way, an image is formed on the surface of the sheet 2.

[0050] (drying process) In the drying process, the control unit 28 heats the sheet 2 to which the ink has been applied to dry the ink. The control unit 28 controls the drying device 34, which is, for example, a dryer, to send hot air at a predetermined temperature to the sheet 2. This allows the ink applied to the surface of the sheet 2 passing under the drying device 34 to dry. The predetermined temperature is not particularly limited, but can be, for example, equal to or higher than the glass transition temperature of the resin particles contained in the ink. Generally, when the sheet 2 to which the ink has been applied is heated to a temperature higher than the glass transition temperature of the resin particles, the resin particles in the ink undergo glass transition. When the sheet 2 is then cooled to a temperature lower than the glass transition temperature, the resin particles that have undergone glass transition solidify. This improves the scratch resistance of the image formed on the sheet 2. Note that the predetermined temperature can be, for example, equal to or higher than (the glass transition temperature + 10°C) and equal to or lower than 110°C, from the viewpoint of easily achieving the above-mentioned effects. The time required to dry the same position on the sheet 2 is not particularly limited, but from the viewpoint of easily obtaining a suitable coating film, it can be, for example, 20 seconds or more and 600 seconds or less.

[0051] (Pressure application process) In the pressure application step, the control unit 28 applies a predetermined pressure to the sheet 2 on which an image has been formed. The control unit 28 controls the tension applied to the sheet 2 being wound around the second roll 6, for example, by adjusting the nip force of the third conveying roller pair 26 and the rotation speed of the second holder 16. In this way, the control unit 28 applies a predetermined pressure to the sheet 2 wound around the second roll 6. Here, the control unit 28 winds the sheet 2 around the second roll 6 so that a pressure of 40 kPa or more and 100 kPa or less is applied to the sheet 2. By applying a predetermined pressure to the sheet 2 on which an image has been formed, the smoothness of the image is further improved. Note that the manner in which pressure is applied to the sheet 2 is not limited to the above. For example, the pressure may be applied by a device that presses the sheet 2 placed on a table with a cylinder or the like. Alternatively, the control unit 28 does not have to apply pressure to the sheet 2.

[0052] In addition, in a device that applies pressure to the sheet 2, the surface of the pressing member (e.g., a cylinder) used to apply the pressure may have relatively large irregularities. Therefore, when pressure is applied to the sheet 2 using such a device, the irregularities on the surface of the pressing member may affect the surface shape of the image. As a result, the developed area ratio Sdr of the coating film may become large at the contact surface with the pressing member. In contrast, in this embodiment, pressure is applied to the sheet 2 when the sheet 2 is wound into a roll. That is, pressure is applied while the sheets 2 are overlapping. As described above, the arithmetic mean height Sa1 of the sheet 2 is relatively small, so pressure can be applied with little effect on the surface shape of the image that comes into contact with the sheet 2. Therefore, a coating film with a lower developed area ratio Sdr can be suitably formed.

[0053] In this inkjet recording method, the above steps are carried out so as to satisfy the following condition (a): (a) When the ratio of the amount of ink ejected in the ejection step to the amount of ink remaining in the drying step is 1:0.05 to 0.15, the amount of ink ejected in the ejection step is 1 mg / cm in 80% or more of a plurality of partial regions randomly selected from the ink-adhered region on the surface of the sheet 2. 2 The developed area ratio Sdr is 6% or less. That is, in this inkjet recording method, as long as the above condition (a) is satisfied, the ink composition, the amount of ink ejected per unit area of ​​the sheet 2, the drying temperature and drying time of the sheet 2 to which the ink is attached, the pressure applied to the sheet 2, etc. are appropriately adjusted. This makes it possible to form a coating film with a low developed area ratio on a highly smooth sheet 2. This makes it possible to form an image with excellent abrasion resistance. In other words, it is possible to provide users with printed matter on which an image with excellent abrasion resistance is formed.

[0054] Furthermore, in the inkjet recording method, as described above, a coating film having a low developed area ratio is formed. That is, the formed coating film has a smoothness similar to that of the sheet 2. Therefore, an image having excellent gloss can be formed.

[0055] In the inkjet recording method, the above steps are preferably carried out so as to satisfy the following condition (b) in addition to the condition (a): (b) when the ratio of the amount of ink ejected in the ejection step to the amount of ink remaining in the drying step is 1:0.05 to 0.15, the amount of ink ejected in the ejection step is 1 mg / cm or more in 80% or more of the partial regions randomly selected from the adhesion region; 2 The arithmetic mean height Sa2 is 8 nm or less.

[0056] In the inkjet recording method, the above steps are preferably carried out so as to satisfy the following condition (c) in addition to the condition (a): (c) when the ratio of the ink ejection amount in the ejection step to the ink remaining amount in the drying step is 1:0.05 to 0.15, the ink ejection amount in the ejection step is 1 mg / cm or more in 80% or more of the partial regions randomly selected from the adhesion region; 2 The root mean square roughness Rq at this time is 10 nm or less.

[0057] By performing the above steps so as to satisfy the above conditions (b) and / or (c), an image with better abrasion resistance and glossiness can be formed. In other words, a printed matter on which an image with better abrasion resistance and glossiness is formed can be provided to a user. Note that it is not essential that the above conditions (b) and / or (c) are satisfied, and the above conditions (b) and / or (c) do not necessarily have to be satisfied. [Example]

[0058] Next, the ink will be specifically described with reference to examples and comparative examples, although the present invention is not limited to these examples in any way.

[0059] (Ink Preparation) Inks of each example and comparative example were prepared by mixing the components shown in Tables 1 and 2. The numerical values ​​in the columns showing each component in each table indicate the content of that component relative to the total amount of each ink, expressed in mass %. For resin particles, the content is shown as a solid content.

[0060] [Table 1]

[0061] [Table 2]

[0062] Using each of the prepared inks, the scratch resistance of the image-forming portion and the glossiness of the image were evaluated according to the methods described below.

[0063] (Preparation of evaluation samples) For each medium (10cm x 10cm) shown in Tables 1 and 2, the amount of ink adhered was 1mg / cm 2 Drawdown was performed so that the ink would be uniform. Thereafter, a constant temperature dryer (DX402 manufactured by Yamato Scientific Co., Ltd.) was used to dry the medium at the drying temperature (heating temperature) and drying time (heating time) shown in Tables 3 and 4 to prepare evaluation samples. Note that for Examples 16 to 21, after drying, each medium with the ink attached was sandwiched between flat SUS plates, and pressure was applied for 12 hours at the load shown in Tables 3 and 4 to prepare evaluation samples. Note that the media shown in Tables 1 and 2 are as follows. PET: Single-phase general PET film 38 μm (Toppan Printing Co., Ltd.) PVC: PVC film for inkjet printing "Bando Grand Messe (registered trademark)" GM-H-EHG PP: OPP film 20 μm (Toppan Printing Co., Ltd.)

[0064] (Measurement of each parameter of the medium and evaluation sample) For each evaluation sample, the surface roughness of the medium and the surface roughness of the formed image were measured using an atomic force microscope (Dimension Icon, manufactured by Bruker) in tapping mode (field of view: 1 μm × 1 μm). The measurements were performed at 10 randomly selected locations from the ink-deposited area of ​​each evaluation sample. Based on the measured values, the arithmetic mean height Sa1 of the medium surface, the developed area ratio Sdr of the formed image surface to the medium surface, the arithmetic mean height Sa2 of the formed image surface, and the root-mean-square roughness Rq of the formed image surface were calculated for each location. The results are shown in Tables 1 to 4. In Table 3, for example, the developed area ratio Sdr of Example 1 indicates that the developed area ratio Sdr of the formed image surface to the medium surface was 6% or less at 80% of the 10 locations (i.e., 8 locations). For Example 11, for example, the arithmetic mean height Sa2 of the formed image was 6 nm or less at 90% of the 10 locations (i.e., 9 locations). In addition, Comparative Examples 1 to 6 show the average values ​​of the developed area ratio Sdr, the arithmetic mean height Sa2, and the root mean square roughness Rq measured at the above 10 locations.

[0065] (Abrasion resistance evaluation) The image-formed portion of each evaluation sample was rubbed 100 times with a cloth using a probe of a Gakushin-type rub fastness tester (AB-301 manufactured by Tester Sangyo Co., Ltd.) under a load of 500 g. After rubbing, the rub resistance of each sample was evaluated visually according to the following criteria. The evaluation results are shown in Tables 3 and 4. AAA: No wear AA: Slight chipping (chip area less than 5%) A: Scraping (scraped area over 5% but less than 10%) B: Scraped (scraped area over 10% to 20%) C: Scraped (scraped area over 20%)

[0066] (Gloss evaluation) The gloss of each evaluation sample was measured at a measurement angle of 60° using a gloss meter (HG-268 manufactured by Suga Test Instruments Co., Ltd.). Then, based on the measured value of each sample, the gloss of the formed image was evaluated according to the following criteria. The evaluation results are shown in Tables 3 and 4. AA: 95 or above A: 90 or more and less than 95 B: 85 or more and less than 90 C: Under 85

[0067] [Table 3]

[0068] [Table 4]

[0069] As shown in Tables 3 and 4, in Examples 1 to 21, generally good results were obtained in the evaluations of abrasion resistance and glossiness.

[0070] In contrast, in Comparative Examples 1 to 6, the developed area ratio Sdr, arithmetic mean height Sa2, and root mean square roughness Rq all have higher values ​​compared to the Examples. Specifically, in Examples 1 to 21, in 80% or more of the area, Sdr is 6% or less, Sa2 is 8 nm or less, and Rq is 10 nm or less, whereas in Comparative Examples 1 to 6, the average values ​​of these values ​​are large and the evaluations of both abrasion resistance and gloss are low. From these results, it can be seen that by forming an image under conditions that satisfy the values ​​of the Examples, it is possible to impart excellent abrasion resistance and gloss to the formed image.

[0071] The ink of Comparative Example 1 does not contain an organic solvent. This is thought to be because the resin particles in the ink are difficult to melt, the coating film is insufficient, and many areas of the resin particles remain in particulate form, resulting in low smoothness and poor abrasion resistance and gloss. These results demonstrate that the organic solvent contributes to the formation of a favorable coating film.

[0072] Furthermore, the drying times were relatively short in Comparative Examples 1 and 2. This is thought to be why the ink did not dry properly, resulting in poor abrasion resistance and gloss. These results demonstrate that sufficient ink drying is necessary to form a highly smooth coating film.

[0073] Furthermore, in Comparative Example 3, the drying temperature was somewhat low, at a temperature (70°C) close to the Tg of the resin particles. This is thought to have made it difficult for the resin particles to melt properly, resulting in poor smoothness of the formed coating film. Furthermore, in Comparative Example 3, the vapor pressure of the organic solvent contained in the ink was high, and the HSP distance between the organic solvent and the resin particles was large. This resulted in poor compatibility between the organic solvent and the resin particles, and the organic solvent evaporated before the resin particles melted into the organic solvent, which is thought to have also contributed to the poor smoothness of the coating film. These results show that the physical properties of the formed coating film change depending on the ink drying temperature and the type of organic solvent used.

[0074] Comparative Examples 4 and 5 are similar to Examples 9 and 10, except for the difference in the resin particle content. Specifically, Comparative Example 4 has a lower resin particle content (3% by mass) than Examples 9 and 10, while Comparative Example 5 has a higher resin particle content (12% by mass) than Examples 9 and 10. It is believed that Comparative Example 4, due to the low resin particle content, was unable to form a suitable coating film on the medium surface, resulting in poor abrasion resistance and gloss. It is also believed that Comparative Example 5, due to the high resin particle content, achieved good abrasion resistance, but lost the smoothness of the coating film, resulting in poor gloss. These results confirm that a suitable coating film can be formed by incorporating an appropriate amount of resin particles.

[0075] Comparative Example 6 is similar to Example 14, except for the use of a different medium. In Comparative Example 6, the arithmetic mean height Sa1 of the medium surface is large. It is believed that the coating film formed on a medium with relatively low smoothness resulted in poor numerical values ​​such as the developed surface area ratio Sdr, and low evaluation results for both abrasion resistance and gloss. These results demonstrate that the physical properties of the coating film formed vary depending on the type of medium.

[0076] Furthermore, Comparative Examples 7 to 10 were evaluated as having good gloss but poor abrasion resistance. Comparative Examples 7 to 10 are similar to Examples 11 to 13 except that they contain resin particles with different Tg's. Specifically, the resin particles of Comparative Examples 7 to 10 have a lower Tg than the resin particles of Examples 11 to 13. These results confirm that resin particles with a low Tg cannot impart suitable robustness to the ink coating after drying, resulting in poor abrasion resistance.

[0077] Furthermore, when comparing each example, Examples 1 to 3 are similar except for the drying time. Comparing Examples 1 to 3, it can be seen that the longer the drying time, the lower the Sdr, Sa2, and Rq values, and the better the abrasion resistance. However, as shown in Example 15, it can be seen that if the drying time is too long, gloss tends to be lost.

[0078] In addition, the drying temperatures of Examples 6 and 7 are slightly lower than those of the other Examples. Specifically, the drying temperature is near the glass transition temperature of the resin particles. However, since the evaluation results are good, it can be seen that even if the drying temperature is near the glass transition temperature, good results can be obtained in both abrasion resistance and gloss as long as the resin particles are contained and an organic solvent having a preferable HSP distance and vapor pressure is blended. Examples 4, 5, and 8 are similar except for the fact that the drying temperatures are different. Comparing these Examples, it can be seen that the higher the drying temperature, the lower the values ​​of Sdr, Sa2, and Rq, and a more suitable coating film can be formed.

[0079] Furthermore, Examples 16 to 21 showed particularly excellent results in both abrasion resistance and gloss. In Examples 15 to 18, pressure was applied to each sample after the ink had dried. This shows that applying pressure to the formed image can produce better results. However, in Example 20, a relatively low pressure was applied, which is thought to have resulted in the coating film not being as smooth as in Examples 16 to 19, and the gloss rating remaining at A. In Example 21, a relatively high pressure was applied, which resulted in the coating film being smoothly smoothed, but which may have caused the medium to deform. This is thought to have resulted in the gloss rating remaining at A. These results show that a more suitable coating film can be formed by adjusting the applied pressure.

[0080] As described above, the formation of a coating film using resin particles is affected by several factors, such as drying temperature, drying time, the presence or absence of an organic solvent, the properties of the organic solvent, and applied pressure. Conventionally, in order to achieve a coating film with the desired abrasion resistance and gloss, conditions for each factor have been examined. However, this examination has been difficult, especially when multiple factors are involved. Therefore, the present inventors focused on the fact that a coating film is formed by the shape change of resin particles from particles to a film due to the above-mentioned factors, and came up with the idea that if this shape change can be captured, the properties of the final coating film can be directly grasped. Then, as in the above-described examples, by specifying values ​​such as the developed area ratio Sdr of the coating film, it is possible to form a coating film with the desired abrasion resistance and gloss.

[0081] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0082] Furthermore, the technical elements described in this specification or drawings may exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings may achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful.

[0083] In the scope of the claims at the time of filing, even if each claim depends on only some of the claims, it is not limited to the fact that each claim can depend on only those some of the claims. To the extent that there is no technical contradiction, each claim can also depend on other claims that were not dependent at the time of filing. In other words, the technology of each claim can be combined in various ways as follows: (Item 1) An inkjet recording method, comprising: a discharge step of discharging ink onto a surface of a medium under a first condition; a drying step of heating the medium under second conditions to dry the ink after the ejection step; Equipped with an arithmetic mean height Sa1 of 5 nm or less in 80% or more of a plurality of first partial regions randomly selected from the surface of the medium; The first condition is: (1) The ink contains resin particles having a glass transition temperature Tg of 50° C. or higher, an organic solvent, and water, and the ink contains 5% by mass or more and 11% by mass or less of the resin particles; The first condition and the second condition are: (2) When the ratio of the amount of ink ejected in the ejection step to the amount of ink remaining in the drying step is 1:0.05 to 0.15, the amount of ink ejected in the ejection step is 1 mg / cm in 80% or more of a plurality of second partial areas randomly selected from the adhesion area on the surface of the medium to which the ink is attached. 2 The deployed area ratio Sdr is 6% or less. The condition is satisfied: Inkjet recording method. (Item 2) The first condition and the second condition further include: (3) When the ratio of the ejection amount of the ink in the ejection step to the remaining amount of the ink in the drying step is 1:0.05 to 0.15, the ejection amount of the ink in the ejection step is 1 mg / cm in 80% or more of the third partial areas among a plurality of third partial areas randomly selected from the adhesion area. 2 The arithmetic mean height Sa2 is 8 nm or less when Item 2. The inkjet recording method according to item 1, wherein the above condition is satisfied. (Item 3) The first condition and the second condition further include: (4) When the ratio of the ejection amount of the ink in the ejection step to the remaining amount of the ink in the drying step is 1:0.05 to 0.15, the ejection amount of the ink in the ejection step is 1 mg / cm in 80% or more of a plurality of fourth partial areas randomly selected from the adhesion area. 2 The root mean square roughness Rq is 10 nm or less. 3. The inkjet recording method according to item 1 or 2, wherein the condition is satisfied. (Item 4) The first condition further includes: (5) The ink is used in which the Hansen solubility parameter distance between the resin particles and the ink in a three-dimensional space represented by the Hansen solubility parameter is 1 or more and 5 or less, and the content of the organic solvent having a vapor pressure of 150 Pa or less at 25°C is 0.5% by mass or more and 10% by mass or less. 4. The inkjet recording method according to any one of items 1 to 3, comprising: (Item 5) The second condition further includes: (6) The inkjet recording method according to any one of items 1 to 4, wherein the heating temperature is (the Tg+10° C.) or higher and 110° C. or lower, and the heating time is 20 seconds or longer and 600 seconds or shorter. (Item 6) The inkjet recording method further comprises: 6. The inkjet recording method according to any one of items 1 to 5, further comprising a pressure applying step of applying a pressure of 40 kPa or more and 100 kPa or less to the medium after the drying step. (Item 7) 7. The inkjet recording method according to item 6, wherein in the pressure applying step, pressure is applied to the medium by winding the medium into a roll. (Item 8) A printed matter obtained by ejecting ink onto a surface of a medium, (1) The arithmetic mean height Sa1 is 5 nm or less in 80% or more of a plurality of first partial regions randomly selected from the non-ink-attached region on the surface of the medium, (2) In 80% or more of a plurality of second partial areas randomly selected from the ink-adhered areas on the surface of the medium, the ink ejection amount is 1 mg / cm 2 The deployed area ratio Sdr is 6% or less. printed matter. (Item 9) (3) In 80% or more of the third partial regions among a plurality of third partial regions randomly selected from the adhesion region, the ink ejection amount is 1 mg / cm 2 Item 9. The printed matter according to item 8, wherein the arithmetic mean height Sa2 is 8 nm or less. (Item 10) (4) In 80% or more of the fourth partial regions among a plurality of fourth partial regions randomly selected from the adhesion region, the ink ejection amount is 1 mg / cm 2 10. The printed matter according to item 8 or 9, wherein the root mean square roughness Rq is 10 nm or less. [Explanation of symbols]

[0084] 2: sheet, 4: first roll, 6: second roll, 10: image forming device, 12: housing, 28: control unit, 30: surface treatment device, 32: head, 33: nozzle, 34: drying device

Claims

1. An inkjet recording method, comprising: a discharge step of discharging ink onto a surface of a medium under a first condition; a drying step of heating the medium under second conditions to dry the ink after the ejection step; Equipped with an arithmetic mean height Sa1 of 5 nm or less in 80% or more of a plurality of first partial regions randomly selected from the surface of the medium; The first condition is: (1) The ink contains resin particles having a glass transition temperature Tg of 50° C. or higher, an organic solvent, and water, and the ink contains 5% by mass or more and 11% by mass or less of the resin particles, The first condition and the second condition are: (2) When the ratio of the amount of ink ejected in the ejection step to the amount of ink remaining in the drying step is 1:0.05 to 0.15, the amount of ink ejected in the ejection step is 1 mg / cm or more in 80% or more of a plurality of second partial areas randomly selected from the adhesion area on the surface of the medium to which the ink is attached. ２ The development area ratio Sdr is 6% or less. The condition is satisfied: Inkjet recording method.

2. The first condition and the second condition further include: (3) When the ratio of the ejection amount of the ink in the ejection step to the remaining amount of the ink in the drying step is 1:0.05 to 0.15, the ejection amount of the ink in the ejection step is 1 mg / cm or more in 80% or more of a plurality of third partial areas randomly selected from the adhesion area. ２ The arithmetic mean height Sa2 is 8 nm or less.

2. The ink jet recording method according to claim 1, wherein the above condition is satisfied.

3. The first condition and the second condition further include: (4) When the ratio of the ejection amount of the ink in the ejection step to the remaining amount of the ink in the drying step is 1:0.05 to 0.15, the ejection amount of the ink in the ejection step is 1 mg / cm or more in 80% or more of a plurality of fourth partial areas randomly selected from the adhesion area. ２ The root mean square roughness Rq is 10 nm or less.

2. The ink jet recording method according to claim 1, wherein the above condition is satisfied.

4. The first condition further includes: (5) The ink is used in which the Hansen solubility parameter distance between the resin particles and the ink in a three-dimensional space represented by the Hansen solubility parameter is 1 or more and 5 or less, and the content of the organic solvent having a vapor pressure of 150 Pa or less at 25°C is 0.5% by mass or more and 10% by mass or less. The inkjet recording method according to claim 1 , comprising:

5. The second condition further includes: (6) The ink jet recording method according to (1), wherein the heating temperature is (the Tg+10° C.) or more and 110° C. or less, and the heating time is 20 seconds or more and 600 seconds or less.

6. The inkjet recording method further comprises: The inkjet recording method according to claim 1 , further comprising a pressure applying step of applying a pressure of 40 kPa or more and 100 kPa or less to the medium after the drying step.

7. The inkjet recording method according to claim 6 , wherein in the pressure applying step, the pressure is applied to the medium by winding the medium into a roll.

8. A printed matter obtained by ejecting ink onto a surface of a medium, (1) The arithmetic mean height Sa1 is 5 nm or less in 80% or more of a plurality of first partial regions randomly selected from the non-ink-attached region on the surface of the medium, (2) In 80% or more of a plurality of second partial regions randomly selected from the ink-adhered region on the surface of the medium, the ink ejection amount is 1 mg / cm ２ The development area ratio Sdr is 6% or less. printed matter.

9. (3) In 80% or more of the third partial regions among a plurality of third partial regions randomly selected from the adhesion region, the ink ejection amount is 1 mg / cm ２ The printed matter according to claim 8, wherein the arithmetic mean height Sa2 is 8 nm or less.

10. (4) In 80% or more of the fourth partial regions among a plurality of fourth partial regions randomly selected from the adhesion region, the ink ejection amount is 1 mg / cm ２ The printed matter according to claim 8, wherein the root mean square roughness Rq is 10 nm or less.

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