Image forming apparatus and image forming method

Abstract

To provide an image forming apparatus that can excellently transfer an intermediate image even on a recording medium having irregularity on surface and can obtain excellent fixability in a system of transferring an intermediate image of an intermediate transfer body onto a recording medium.SOLUTION: An image forming apparatus comprises: first ejection means for ejecting a first ink onto an intermediate transfer body; first heating means for heating the intermediate transfer body with the first ink ejected thereon; second ejection means for ejecting second ink onto the intermediate transfer body heated by the first heating means; second heating means for heating the intermediate transfer body with the second ink ejected thereon; and transfer means for transferring, onto the recording medium, an intermediate image formed on the intermediate transfer body by bringing the intermediate transfer body heated by the second heating means into contact with a recording medium, heating and pressurizing them. Therein: the first and second inks contain first resin and second resin, respectively; surface free energy of the intermediate transfer body is 20 to 40 mN / m; the first and second heating means perform heating at 120 to 160°C; and a glass transition point of the first resin is higher than a glass transition point of the second resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and an image forming method. [Background technology]

[0002] 2. Description of the Related Art Inkjet printers, which are image forming devices, have advantages such as low noise, low running costs, and ease of color printing, and are widely used as output devices for digital signals.

[0003] Widely used inks for such inkjet printers include, for example, solvent-based inks using organic solvents as solvents and ultraviolet-curable inks containing polymerizable monomers as their main components. However, the solvent-based inks raise concerns about the environmental impact of evaporation of the organic solvent. Furthermore, the ultraviolet-curable inks have limited options for polymerizable monomers due to safety concerns.

[0004]

[0003] Therefore, ink sets containing aqueous inks with low environmental impact have been proposed. However, when aqueous inks are printed directly onto plain paper from an ejection device, the ink penetrates into the paper layer, making it difficult to satisfy all of the characteristics required, such as image density, image clarity, image drying, image bleeding, and image show-through. In response to this, a technology has been proposed in which ink is ejected onto an intermediate transfer body, and then the ink held on the intermediate transfer body is transferred to a recording medium to obtain a recorded image.

[0005] Patent Documents 1 and 2 propose that ink ejected from an inkjet head is deposited on an intermediate transfer body, the water content in the ink is evaporated and concentrated by a heating element, and then the intermediate transfer body is pressed against a recording medium, and the ink on the intermediate transfer body is transferred to the recording medium, fixing the recorded image. This is expected to prevent the ink from penetrating into the paper layer, and to solve problems such as image drying, image bleeding, and image show-through. Summary of the Invention [Problem to be solved by the invention]

[0006] However, when fixing a recorded image (intermediate image) on an intermediate transfer member to a recording medium with an uneven surface, there is a risk of voids forming between the recorded image on the intermediate transfer member and the recording medium when the intermediate transfer member and the recording medium are pressed together. If such voids form, the pressure required for transfer cannot be applied, and there is a risk of transfer residue, where the recorded image remains on the intermediate transfer member. If good transferability is not achieved and transfer residue occurs, this can lead to problems such as a decrease in the density of the transferred recorded image and deterioration of the intermediate transfer member. Furthermore, if good transferability is not achieved, the image will not be fixed well to the recording medium, and good image density may not be achieved.

[0007] Therefore, the present invention aims to provide an image forming apparatus that can transfer an intermediate image from an intermediate transfer body to a recording medium, and can obtain good fixation properties, even if the recording medium has an uneven surface. [Means for solving the problem]

[0008] In order to solve the above problem, an image forming apparatus of the present invention includes a first ejection means that ejects a first ink onto an intermediate transfer body, a first heating means that heats the intermediate transfer body onto which the first ink has been ejected, a second ejection means that ejects a second ink onto the intermediate transfer body heated by the first heating means, a second heating means that heats the intermediate transfer body onto which the second ink has been ejected, and a transfer means that brings the intermediate transfer body heated by the second heating means into contact with a recording medium, heats and pressurizes the intermediate transfer body, and transfers an intermediate image formed on the intermediate transfer body to the recording medium, wherein the first ink contains a first resin, the second ink contains a second resin, the surface free energy of the intermediate transfer body is 20 mN / m or more and 40 mN / m or less, the first heating means and the second heating means heat the intermediate transfer body at a temperature of 120°C or more and 160°C or less, and the glass transition point of the first resin is higher than the glass transition point of the second resin. [Effects of the Invention]

[0009] According to the present invention, an image forming apparatus can be provided that, in a method of transferring an intermediate image from an intermediate transfer body to a recording medium, can transfer the intermediate image well even to a recording medium with an uneven surface, and can obtain good fixability. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0011] The image forming apparatus and image forming method according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiments, and other modifications, additions, corrections, deletions, and other changes can be made within the scope of what a person skilled in the art can conceive. Any embodiment that achieves the functions and effects of the present invention is included in the scope of the present invention.

[0012] The image forming apparatus of the present invention comprises a first ejection means for ejecting a first ink onto an intermediate transfer body, a first heating means for heating the intermediate transfer body onto which the first ink has been ejected, a second ejection means for ejecting a second ink onto the intermediate transfer body heated by the first heating means, a second heating means for heating the intermediate transfer body onto which the second ink has been ejected, and a transfer means for bringing the intermediate transfer body heated by the second heating means into contact with a recording medium, applying heat and pressure, and transferring an intermediate image formed on the intermediate transfer body to the recording medium, wherein the first ink contains a first resin, the second ink contains a second resin, the surface free energy of the intermediate transfer body is 20 mN / m or more and 40 mN / m or less, the first heating means and the second heating means heat at a temperature of 120°C or more and 160°C or less, and the glass transition point of the first resin is higher than the glass transition point of the second resin.

[0013] The image forming method of the present invention includes a first ejection step of ejecting a first ink onto an intermediate transfer body, a first heating step of heating the intermediate transfer body onto which the first ink has been ejected, a second ejection step of ejecting a second ink onto the intermediate transfer body heated in the first heating step, a second heating step of heating the intermediate transfer body onto which the second ink has been ejected, and a transfer step of contacting the intermediate transfer body heated in the second heating step with a recording medium, and applying heat and pressure to the intermediate transfer body, thereby transferring an intermediate image formed on the intermediate transfer body to the recording medium, wherein the first ink contains a first resin, the second ink contains a second resin, the surface free energy of the intermediate transfer body is 20 mN / m or more and 40 mN / m or less, the first heating step and the second heating step are performed at a temperature of 120°C or more and 160°C or less, and the glass transition point of the first resin is higher than the glass transition point of the second resin.

[0014] In this embodiment, the first ink is ejected onto the intermediate transfer body, followed by heating by the first heating means, the second ink is ejected onto the intermediate transfer body, and heating by the second heating means. In this manner, a layer of the first ink and a layer of the second ink are formed on the intermediate transfer body, forming an intermediate image. The layer of the first ink and the layer of the second ink may be referred to as a coating film, a coating film layer, or the like, respectively. The intermediate image may also be referred to as a recorded image, or the like. The first ink may also be referred to as the first ink, and the second ink may also be referred to as the second ink.

[0015] The intermediate image formed on the intermediate transfer body is transferred to a recording medium by a transfer means. The transfer means brings the intermediate transfer body into contact with the recording medium, applies heat and pressure, and transfers the intermediate image to the recording medium. The intermediate image on the intermediate transfer body is sometimes referred to as a recorded image.

[0016] In this embodiment, the surface free energy of the intermediate transfer body is 20 mN / m or more and 40 mN / m or less, and wettability is improved by increasing the affinity between the first ink and the intermediate transfer body. This allows the intermediate image to be fixed to the recording medium before beading or bleeding of the image occurs. The process of bringing the intermediate transfer body and the recording medium into contact with each other, applying heat and pressure, and transferring the intermediate image to the recording medium may also be referred to as fixing.

[0017] The surface free energy of the intermediate transfer body can be measured by the dispersion force component γ L d , dipole force component γ L p , hydrogen bond component γ L dh By measuring the contact angle with the intermediate transfer body for three types of liquid samples with known contact angles and applying the results to the following formula derived from the Young-Dupre equation and the extended Hawkes equation, each component of the surface free energy of the intermediate transfer body can be calculated using simultaneous equations.

[0018]

number

[0019] At this time, γ S d , γ S p , γ S h respectively represent the dispersion force component, dipole force component, and hydrogen bond component of the intermediate transfer member, and γL represents the surface tension of the liquid. Surface tension of the liquid γ L An automatic surface tensiometer (DY-300, manufactured by Kyowa Interface Science Co., Ltd.) can be used to measure the surface tension, and a contact angle meter (DMo-501, manufactured by Kyowa Interface Science Co., Ltd.) can be used to measure the contact angle.

[0020] In this embodiment, the glass transition temperature of the first resin contained in the first ink is higher than the glass transition temperature of the second resin contained in the second ink. In this embodiment, inks having this relationship are used, and an intermediate image is formed by ejecting the second ink onto the first ink. This makes it easier for the ink coating to conform to the irregularities on the surface of the recording medium when the intermediate transfer body and the recording medium are heated and pressurized in the transfer process. This improves the releasability of the layer of the first ink from the intermediate transfer body, improving transferability and image fixability.

[0021] In this embodiment, the first heating step by the first heating means and the second heating step by the second heating means are performed at a temperature of 120° C. or higher and 160° C. or lower. This improves transferability and image fixability. If the heating temperature is outside this range, good transferability and good image fixability cannot be obtained.

[0022] According to the present invention, in a method of transferring an intermediate image from an intermediate transfer member to a recording medium, the intermediate image can be transferred satisfactorily even to a recording medium having an uneven surface, and good fixation can be achieved. The present invention allows for good transfer of the intermediate image to a recording medium such as plain paper having an uneven surface. Furthermore, because of the good transferability, residual transfer from the intermediate transfer member can be suppressed, and a decrease in the density of the image (transferred image) formed on the recording medium and deterioration of the intermediate transfer member can be suppressed. Furthermore, because of the good fixation, the image density of the transferred image can be improved.

[0023] Other embodiments included in the present invention will now be described. In the present invention, it is preferable that the first ink contains at least the first resin, an organic solvent, a surfactant, and a colorant, and that the second ink contains at least the second resin, an organic solvent, and a surfactant, but does not contain a colorant. This has the advantage that it is possible to achieve both the transfer function of the second ink onto the recording medium and improvement in the abrasion resistance of the image transferred by the first ink. The intermediate image formed on the intermediate transfer member includes a layer of the first ink and a layer of the second ink formed on the layer of the first ink. When the intermediate image is transferred to a recording medium to form a transfer image on the recording medium, the transfer image includes a layer of the second ink and a layer of the first ink formed on the layer of the second ink. Therefore, when the second ink does not contain a colorant, the transfer image transferred to the recording medium has the advantage of being able to perform both the transfer function to the recording medium using the second ink and the image formation function using the first ink.

[0024] In the present invention, it is preferable that the weight loss rate of the first ink and the second ink due to heating by the first heating means and heating by the second heating means is 70% or more and 90% or less. This has the advantage that the first ink and the second ink are prevented from mixing, and the transfer function of the coating layer formed by the second ink is improved. The reduction rate can be set within the above range by, for example, adjusting the heating with hot air, a halogen heater, infrared heating, etc. The reduction rate is measured by weight measurement.

[0025] The solid content of the second resin contained in the second ink is preferably 10% by mass or more and 15% by mass or less, which can improve the adhesion between the first ink and the second ink on the intermediate transfer body and can also improve the ejection properties of the second ink.

[0026] The second resin contained in the second ink is preferably a urethane resin, which can improve image fixation.

[0027] The transfer means preferably performs the transfer by raising the temperature of the intermediate transfer body above the glass transition point of the first resin.Similarly, the transfer step preferably performs the transfer by raising the temperature of the intermediate transfer body above the glass transition point of the first resin. By doing so, the coating layer formed by the first ink is softened and the releasability from the intermediate transfer member is improved.

[0028] The intermediate transfer member preferably contains ethylene propylene diene rubber, which can improve the releasability of the intermediate transfer member and the intermediate image, and can also improve the image quality on the intermediate transfer member.

[0029] The transfer means preferably has a thermal transfer roller and an opposing roller facing the thermal transfer roller, and thermal transfer is performed by passing the intermediate transfer body and the recording medium through a nip formed by the thermal transfer roller and the opposing roller. In this case, transferability can be further improved.

[0030] (Example of an image forming apparatus and an image forming method) Next, the image forming apparatus of the present invention will be described in detail. Fig. 1 is a schematic diagram for explaining an example of the image forming apparatus.

[0031] The image forming apparatus 1 of this example has first heads 2A to 2D, a second head 5, a heater 3, a heater 4, a transport roller 7, an opposing roller 6, a fixing roller 9, and an intermediate transfer belt 10. In the drawing, the black arrow indicates the rotation direction of the intermediate transfer belt 10, and the white arrow indicates the transport direction of the recording medium 11.

[0032] The first heads 2A to 2D are an example of a first ejection means, and eject a first ink (first ink) onto the intermediate transfer belt 10. Liquid ejection heads such as inkjet recording heads can be used as the first heads 2A to 2D. Although four first heads are shown in the figure, the present invention is not limited to this, and the number of first heads can be changed as appropriate. There may be one first head or multiple first heads. When the first heads 2A to 2D are described without distinction, they may be referred to as first head 2.

[0033] The first ink is, for example, an ink containing a color material. The first heads 2A to 2D eject color inks such as black, cyan, magenta, yellow, etc. Alternatively, they may eject white ink, etc.

[0034] The second head 5 is an example of a second ejection means, and ejects a second ink (second ink) onto the intermediate transfer belt 10. As the second head 5, a liquid ejection head such as an inkjet recording head can be used, similar to the first head 2.

[0035] As the first head 2 and the second head 5, for example, a liquid ejection head using a so-called piezo type, thermal type, or electrostatic type can be used. A piezoelectric liquid ejection head uses a piezoelectric element as a pressure generating means for pressurizing the ink in the ink flow path, and deforms a vibration plate that forms the wall surface of the ink flow path, changing the internal volume of the ink flow path and ejecting ink droplets. A thermal liquid ejection head uses a heating resistor to heat ink in an ink flow path, generating bubbles to eject ink droplets. An electrostatic liquid ejection head has a vibration plate that forms the wall of the ink flow path and an electrode arranged opposite each other, and the vibration plate is deformed by the electrostatic force generated between the vibration plate and the electrode, thereby changing the volume of the ink flow path and ejecting ink droplets. The ink may also be stored in an ink storage container such as an ink cartridge.

[0036] Heater 3 is an example of a first heating means and heats the intermediate transfer belt 10 onto which the first ink has been ejected. Heater 4 is an example of a second heating means and heats the intermediate transfer belt 10 onto which the second ink has been ejected. In this example, heaters 3 and 4 heat the intermediate transfer belt 10 from the side (back side) opposite to the side (front side) onto which the ink has been ejected.

[0037] The first heating means and the second heating means can be appropriately selected, and heating means such as a halogen lamp and hot air can be used.

[0038] The first and second heating means are set to a temperature at which the intermediate transfer body and the recorded image reach a temperature of 120°C or higher and 160°C or lower. In this case, the transferability of the intermediate image (recorded image) is improved. If the temperature is lower than 120°C, the recorded image is not sufficiently dried and solidified, reducing the strength of the ink coating, causing the ink coating to break during transfer and reducing the transferability of the recorded image. If the temperature is higher than 160°C, the recorded image dries excessively, causing the ink coating to break during transfer and reducing the image quality of the recorded image.

[0039] Intermediate transfer belt 10 is an example of an intermediate transfer body. Intermediate transfer belt 10 is supported by a transport roller 7 and an opposing roller 6, and rotates in the direction of the black arrow in the figure. The rotation of intermediate transfer belt 10 may also be referred to as transport. The transport roller 7 and opposing roller 6 are rotationally driven by gears, for example.

[0040] The fixing roller 9 and the opposing roller 6 are an example of a transfer means. The fixing roller 9 heats the intermediate transfer belt 10. For example, the fixing roller 9 has a heat source inside to heat the intermediate transfer belt 10. The fixing roller 9 may be, for example, a fixing belt used in an electrophotographic system.

[0041] The opposing roller 6 is disposed in a position opposite to the fixing roller 9. A nip is formed between the fixing roller 9 and the opposing roller 6, and by passing the intermediate transfer belt 10 and the recording medium 11 through the nip, heat and pressure can be applied to the intermediate transfer belt 10 and the recording medium 11. By applying heat and pressure to the intermediate transfer belt 10 and the recording medium 11, the intermediate image is transferred to the recording medium 11. This type of transfer may also be referred to as fixing.

[0042] The first ink is ejected from the first head 2 onto the intermediate transfer belt 10, which is heated by the heater 3, and the second ink is ejected from the second head 5 onto the intermediate transfer belt 10, which is heated by the heater 3. Heating by the heaters 3 and 4 causes the volatile components in the ink to evaporate. By ejecting the ink and heating the intermediate transfer body in this manner, an intermediate image is formed on the intermediate transfer belt 10. Next, the intermediate transfer belt 10 transports the intermediate image to the transfer means, which transfers the intermediate image onto the recording medium 11 by the mechanical pressure of the fixing roller 9.

[0043] The surface free energy of the intermediate transfer member may be selected as appropriate as long as it is 20 mN / m or more and 40 mN / m or less. The surface free energy of the intermediate transfer member satisfies the above range on the side of the intermediate transfer member onto which the ink is ejected.

[0044] Examples of the surface material of the intermediate transfer body that can be used include rubber materials such as silicone rubber, fluororubber, urethane rubber, natural rubber (NR), styrene butadiene rubber (SBR), nitrile rubber (NBR), chloroprene (CR), butyl rubber (BR), ethylene propylene rubber (EPDM), and Hypalon. Ethylene propylene rubber (EPDM) is particularly preferred because it can improve the releasability of the intermediate transfer body and the intermediate image and the image quality on the intermediate transfer body.

[0045] The layer structure of the intermediate transfer member can be appropriately selected and may be a single layer or multiple layers. When the intermediate transfer member has multiple layers, it is preferable to use the above-mentioned surface material for the surface layer, and it is particularly preferable to use ethylene propylene rubber for the surface layer.

[0046] (First Ink) A detailed example of the first ink (first ink) will be described below. The first ink contains a first resin, and may also contain water, an organic solvent, a surfactant, and a colorant, and may further contain other components as necessary. Herein, the first ink may be simply referred to as ink.

[0047] <Organic solvents> The organic solvent used in the present invention is not particularly limited, and any water-soluble organic solvent can be used, including, for example, polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.

[0048] Specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, and the like. Polyhydric alcohols such as pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether. polyhydric alcohol alkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone; amides such as formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; amines such as monoethanolamine, diethanolamine, and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; propylene carbonate; and ethylene carbonate.

[0049] It is preferable to use an organic solvent having a boiling point of 250° C. or less, since it not only functions as a wetting agent but also provides good drying properties.

[0050] Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.

[0051] Specific examples of glycol ether compounds include polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

[0052] Polyol compounds having 8 or more carbon atoms and glycol ether compounds can improve the permeability of ink when paper is used as the recording medium.

[0053] The content of the organic solvent in the ink is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of the drying property and ejection reliability of the ink, however, the content is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

[0054] <Water> The water content in the ink is not particularly limited and can be selected appropriately depending on the purpose, but from the viewpoint of the drying property and ejection reliability of the ink, it is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass to 60% by mass.

[0055] <Colorant>

[0056] The coloring material is not particularly limited, and pigments and dyes can be used. The pigment may be an inorganic pigment or an organic pigment. These may be used alone or in combination of two or more. Mixed crystals may also be used.

[0057] Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments. As inorganic pigments, titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used. In addition, examples of organic pigments that can be used include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments), dye chelates (e.g., basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, and aniline black. Of these pigments, those with good affinity for the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.

[0058] Specific examples of pigments for black include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, metals such as copper, iron (CI Pigment Black 11), and titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1).

[0059] In addition, for color, CI Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, CI Pigment Yellow Ranges 5, 13, 16, 17, 36, 43, 51, CI Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88 , 101 (Red Iron), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, CI Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38; CI Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.

[0060] The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone, or two or more types may be used in combination. Examples of the dyes include CI Acid Yellow 17, 23, 42, 44, 79, 142, CI Acid Red 52, 80, 82, 249, 254, 289, CI Acid Blue 9, 45, 249, CI Acid Black 1, 2, 24, 94, CI Food Black 1, 2, CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, CI Direct Red 1, 4, 9, 80, 81, 225, 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, CI Directed Black 19, 38, 51, 71, 154, 168, 171, 195, and CI Reactive Red. 14, 32, 55, 79, 249, and CI Reactive Black 3, 4, and 35.

[0061] The content of the coloring material in the ink is preferably from 0.1% to 15% by mass, more preferably from 1% to 10% by mass, from the viewpoints of improving image density, good fixability, and ejection stability.

[0062] Methods for dispersing a pigment to obtain an ink include a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of dispersing the pigment by coating the surface of the pigment with a resin, and a method of dispersing the pigment using a dispersant.

[0063] As a method for introducing a hydrophilic functional group into a pigment to make it a self-dispersible pigment, for example, a method of adding a functional group such as a sulfone group or a carboxyl group to a pigment (e.g., carbon) to make it dispersible in water can be mentioned.

[0064] One method for dispersing a pigment by coating its surface with a resin is to encapsulate the pigment in microcapsules to make it dispersible in water. This can be rephrased as a resin-coated pigment. In this case, it is not necessary for all of the pigments blended into the ink to be coated with resin; uncoated or partially coated pigments may be dispersed in the ink, provided that the effects of the present invention are not impaired.

[0065] Examples of the method for dispersing using a dispersant include a method for dispersing using a known low molecular weight dispersant or a high molecular weight dispersant, such as a surfactant.

[0066] As the dispersant, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. can be used depending on the pigment.

[0067] RT-100 (nonionic surfactant) manufactured by Takemoto Yushi Co., Ltd. and sodium naphthalenesulfonate formalin condensate can also be suitably used as dispersants.

[0068] The dispersants may be used alone or in combination of two or more.

[0069] <Pigment dispersion> Ink can be obtained by mixing a pigment with water, an organic solvent, or other materials. Alternatively, ink can be produced by mixing a pigment with other materials such as water and a dispersant to form a pigment dispersion, and then mixing the resulting mixture with water, an organic solvent, or other materials.

[0070] The pigment dispersion is obtained by mixing and dispersing water, a pigment, a pigment dispersant, and optionally other components, and adjusting the particle size. Dispersion is preferably performed using a disperser.

[0071] Although there are no particular restrictions on the particle size of the pigment in the pigment dispersion, the maximum frequency, calculated as the maximum number, is preferably 20 nm or more and 500 nm or less, and more preferably 20 nm or more and 150 nm or less, in order to improve the dispersion stability of the pigment and image quality such as ejection stability and image density. The particle size of the pigment can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0072] The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of obtaining good ejection stability and increasing image density, the content is preferably 0.1% by mass or more and 50% by mass or less, and more preferably 0.1% by mass or more and 30% by mass or less. It is preferable that the pigment dispersion is degassed, if necessary, by filtering coarse particles using a filter, a centrifugal separator, or the like.

[0073] <Resin> The type of resin (first resin) contained in the ink is not particularly limited and can be appropriately selected depending on the purpose. Examples include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic styrene resin, and acrylic silicone resin.

[0074] Resin particles made of these resins may also be used. The resin particles are dispersed in water as a dispersion medium to form a resin emulsion, which can be mixed with materials such as coloring materials and organic solvents to obtain an ink. The resin particles may be appropriately synthesized or commercially available. These may be used alone or in combination of two or more types of resin particles.

[0075] The volume average particle size of the resin particles is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of obtaining good fixing properties and high image hardness, the volume average particle size is preferably 10 nm or more and 1,000 nm or less, more preferably 10 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 100 nm or less.

[0076] The volume average particle size can be measured using, for example, a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0077] The resin content is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of fixability and ink storage stability, however, it is preferably from 1% by mass to 30% by mass, and more preferably from 5% by mass to 20% by mass, of the total amount of ink.

[0078] There are no particular restrictions on the particle size of the solids in the ink and they can be selected appropriately depending on the purpose. However, to improve image quality such as ejection stability and image density, the maximum frequency, calculated as the maximum number, is preferably 20 nm or more and 1000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solids include resin particles and pigment particles. Particle size can be measured using a particle size analyzer (Nanotrac Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0079] <Additives> If necessary, surfactants, antifoaming agents, antiseptic and antifungal agents, antirust agents, pH adjusters, etc. may be added to the ink.

[0080] <Surfactant> As the surfactant, any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants and anionic surfactants can be used.

[0081] Silicone surfactants are not particularly limited and can be appropriately selected depending on the purpose.Among them, those that do not decompose even at high pH are preferred, such as side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end modified polydimethylsiloxane of side chain, and those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are particularly preferred because they exhibit good properties as aqueous surfactants.In addition, polyether-modified silicone surfactants can also be used as the silicone surfactant, and examples thereof include compounds in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylsiloxane.

[0082] As fluorosurfactants, for example, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain are particularly preferred due to their low foaming properties. Examples of the perfluoroalkyl sulfonic acid compounds include perfluoroalkyl sulfonic acids and perfluoroalkyl sulfonate salts. Examples of the perfluoroalkyl carboxylic acid compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylate salts. Examples of the polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain include sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain, and salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain. Counterions of the salts in these fluorosurfactants include Li, Na, K, NH, NHCHCHOH, NH(CHCHOH), NH(CHCHOH), and the like.

[0083] Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.

[0084] Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and ethylene oxide adducts of acetylene alcohol.

[0085] Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzenesulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates. These may be used alone or in combination of two or more.

[0086] The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include side-chain-modified polydimethylsiloxane, both-end-modified polydimethylsiloxane, one-end-modified polydimethylsiloxane, and both-end-modified side-chain polydimethylsiloxane. Polyether-modified silicone surfactants having a polyoxyethylene group or a polyoxyethylene-polyoxypropylene group as the modifying group are particularly preferred because they exhibit good properties as aqueous surfactants.

[0087] Such surfactants may be appropriately synthesized or commercially available products, such as those available from BYK-Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.

[0088] The polyether-modified silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose. For example, it may be a surfactant represented by general formula (S-1) in which a polyalkylene oxide structure is introduced into the Si moiety side chain of dimethylpolysiloxane.

[0089] [ka]

[0090] (In the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R' represents an alkyl group.)

[0091] As the polyether-modified silicone surfactant, commercially available products can be used, such as KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX (Nihon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Dow Corning Toray Silicone Co., Ltd.), BYK-33, BYK-387 (BYK-Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicone Co., Ltd.).

[0092] The fluorine-based surfactant is preferably a compound having 2 to 16 fluorine-substituted carbon atoms, more preferably a compound having 4 to 16 fluorine-substituted carbon atoms.

[0093] Examples of fluorine-based surfactants include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chains. Among these, polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chains are preferred because they have low foaming properties, and fluorine-based surfactants represented by general formula (F-1) and general formula (F-2) are particularly preferred.

[0094] [ka]

[0095] In the compound represented by the above general formula (F-1), m is preferably an integer of 0 to 10, and n is preferably an integer of 0 to 40 in order to impart water solubility.

[0096] C n F 2n+1 -CH2CH(OH)CH2-O-(CH2CH2O) a -Y General formula (F-2)

[0097] In the compound represented by the general formula (F-2), Y is H or C m F 2m+1 where m is an integer from 1 to 6, or CH2CH(OH)CH2-C m F 2m+1 where m is an integer between 4 and 6, or C p H 2p+1 where p is an integer from 1 to 19, n is an integer from 1 to 6, and a is an integer from 4 to 14.

[0098] The fluorine-based surfactant may be a commercially available product, such as Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, or S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, or FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F-1405, or F-474 (all manufactured by Dainippon Ink and Chemicals, Inc.); Zonyl TBS, FSP, FSA, or FSN- 100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours Corporation); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Corporation), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omnova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), and the like. Among these, FS-3100, FS-34, and FS-300 manufactured by Chemours Corporation, FT-110, FT-250, FT-251, FT-400S, FT-150, and FT-400SW manufactured by Neos Corporation, Polyfox PF-151N manufactured by Omnova, and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferred, as they provide good print quality, particularly significant improvements in color development, penetration into paper, wettability, and dye leveling.

[0099] The content of the surfactant in the ink is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoints of excellent wettability and ejection stability and improved image quality, it is preferably 0.001% by mass or more and 5% by mass or less, and more preferably 0.05% by mass or more and 5% by mass or less.

[0100] <Antifoaming agent> The antifoaming agent is not particularly limited, and examples thereof include silicone-based antifoaming agents, polyether-based antifoaming agents, fatty acid ester-based antifoaming agents, and the like. These may be used alone or in combination of two or more. Among these, silicone-based antifoaming agents are preferred from the viewpoint of excellent defoaming effect.

[0101] <Antiseptic and antifungal agent> The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one and the like.

[0102] <Rust preventive agent> The rust preventive agent is not particularly limited, and examples thereof include acid sulfite, sodium thiosulfate, and the like.

[0103] <pH adjuster> The pH adjuster is not particularly limited as long as it can adjust the pH to 7 or more, and examples thereof include amines such as diethanolamine and triethanolamine.

[0104] (Second ink) The second ink (second ink) contains a second resin, and may also contain water, an organic solvent, and a surfactant, and may further contain other components as necessary. As described above, it is preferable that the second ink does not contain a coloring material.

[0105] The organic solvent, water, and additives used in the second ink can be the same as those in the first ink, and the preferred contents are also the same. Therefore, the description of common matters is omitted here.

[0106] The second resin used in the second ink may be the same as the resin described for the first ink. In particular, the second resin is preferably a urethane resin. In this case, image fixation can be improved. However, as explained above, it is necessary to satisfy the relationship that the glass transition point of the first resin is higher than the glass transition point of the second resin.

[0107] The content of the second resin in the second ink is preferably 1% by mass or more and 30% by mass or less relative to the total amount of ink from the viewpoints of ink fixability and ink storage stability, and more preferably 10% by mass or more and 15% by mass or less from the viewpoints of adhesion between the first ink on the intermediate transfer body and the recording medium and ejection reliability. [Example]

[0108] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to these examples.

[0109] (Preparation of first ink) The first ink was prepared as follows.

[0110] <Preparation of Black Dispersion> The ingredients in the following formula are premixed and then milled in a disk-type bead mill (Shinmaru Entertainment Co., Ltd.). The mixture was dispersed in a KDL type dispersion machine (manufactured by Eprise Co., Ltd., media: zirconia balls with a diameter of 0.3 mm) for 7 hours, and a black pigment dispersion was obtained.

[0111] CI Pigment Black 7 15% by weight Anionic surfactant (trade name: Paionin A-51-B, manufactured by Takemoto Oil & Fat Co., Ltd.) 2% by mass Ion-exchanged water 83% by mass

[0112] <Preparation of Urethane Resin Emulsion A> A product name SF-150 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as the urethane resin emulsion A. The urethane resin emulsion A corresponds to the first resin (first resin), and has a glass transition temperature Tg of (40)°C.

[0113] <Preparation of first ink> The black pigment dispersion and urethane resin emulsion A obtained above were mixed with the following components. Note that the "remainder" of pure water refers to the amount such that the total of all components constituting the ink is 100.0% by mass.

[0114] Black pigment dispersion (pigment content: 15.0% by mass) 19.4% by mass Urethane resin emulsion A (resin content: 30.0% by mass) 27.2% by mass Propylene glycol 25.0% by mass Octadiol 3.0% by mass 2-amino-2-ethyl-1,3-propanediol 0.2% by mass Silface SAG503A (Nissin Chemical Industry Co., Ltd.) 1.2% by mass ·Pure water residue

[0115] (Preparation of second ink) A second ink was prepared as follows.

[0116] <Preparation of Urethane Resin Emulsion B> SF-460 (product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as the urethane resin emulsion B. The resin solid content was 37.8% by mass.

[0117] <Preparation of Urethane Resin Emulsion C> SF-820 (product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as the urethane resin emulsion C. The resin solid content was 30.3% by mass.

[0118] <Preparation of Urethane Resin Emulsion D> A product name W-5661 (manufactured by Mitsui Chemicals) was used as the urethane resin emulsion D. The resin solid content was 34.8% by mass.

[0119] <Preparation of Urethane Resin Emulsion E> Product name W-6110 (manufactured by Mitsui Chemicals) was used as the urethane resin emulsion E. The resin solid content was 32.5% by mass.

[0120] <Preparation of Acrylic Resin Emulsion A> TOCRYL BCX-8111 (manufactured by Toyochem) was used as the acrylic resin emulsion A. The resin solid content was 58.0% by mass.

[0121] <Preparation of Acrylic Resin Emulsion B> TOCRYL W-168 (manufactured by Toyochem) was used as the acrylic resin emulsion B. The resin solid content was 49.5% by mass.

[0122] <Preparation of Acrylic Resin Emulsion C> TOCRYL X-4403 (manufactured by Toyochem) was used as the acrylic resin emulsion C. The resin solid content was 50.0% by mass.

[0123] <Preparation of second ink A> The resin urethane emulsion A obtained above was mixed with the following components to prepare second ink A. Note that the "balance" of pure water refers to the amount such that the total of all components constituting the ink is 100.0% by mass.

[0124] Urethane resin emulsion A (resin solid content: 30.0% by mass) 40.0% by mass Propylene glycol 25.0% by mass Octanediol 3.0% by mass 2-amino-2-ethyl-1,3-propanediol 0.2% by mass Silface SAG503A (Nissin Chemical Industry Co., Ltd.) 1.2% by mass Surfynol AD-01 (Nissin Chemical Industry Co., Ltd.) 0.5% by mass ·CHES (Dojindo Chemical Research Institute) 0.05% by mass ·Pure water residue

[0125] <Preparation of second ink B> The urethane resin emulsion A used in preparing the second ink A was changed to urethane resin emulsion B, and the amount added was changed to 32.0% by mass. In addition, the amount of propylene glycol added was changed to 10.0% by mass. Apart from these two changes, the components were mixed in the same manner as in the second ink A to prepare the second ink B.

[0126] <Preparation of second ink C> Second ink C was prepared by mixing the various components in the same manner as second ink A, except that the urethane resin emulsion A used in preparing second ink A was changed to urethane resin emulsion C and the amount added was changed to 39.9% by mass.

[0127] <Preparation of second ink D> The urethane resin emulsion A used in preparing the second ink A was changed to urethane resin emulsion D, and the amount added was changed to 34.7% by mass. In addition, the amount of propylene glycol added was changed to 10.0% by mass. Other than these two changes, the components were mixed in the same manner as in the second ink A to prepare the second ink D.

[0128] <Preparation of second ink E> Second ink B was prepared by mixing the components in the same manner as second ink A, except that the urethane resin emulsion A used in preparing second ink A was changed to urethane resin emulsion E and the amount added was changed to 37.2 mass%.

[0129] <Preparation of second ink F> Second ink F was prepared by mixing the various components in the same manner as second ink A, except that the urethane resin emulsion A used in preparing second ink A was changed to acrylic resin emulsion A and the amount added was changed to 20.8% by mass.

[0130] <Preparation of second ink G> Second ink G was prepared by mixing the various components in the same manner as second ink A, except that the urethane resin emulsion A used in preparing second ink A was changed to acrylic resin emulsion B and the amount added was changed to 24.4% by mass.

[0131] <Preparation of second ink H> Second ink H was prepared by mixing the various components in the same manner as second ink A, except that the urethane resin emulsion A used in preparing second ink A was changed to acrylic resin emulsion C and the amount added was changed to 24.2 mass%.

[0132] <Preparation of second ink I> Second ink I was prepared by mixing the components in the same manner as in second ink A, except that the amount of urethane resin emulsion A used in preparing second ink A was changed to 36.4 mass %.

[0133] <Preparation of second ink J> Second ink J was prepared by mixing the components in the same manner as second ink A, except that the amount of urethane resin emulsion A used in preparing second ink A was changed to 46.6 mass %.

[0134] <Preparation of second ink K> Second ink K was prepared by mixing the components in the same manner as second ink A, except that the amount of urethane resin emulsion A used in preparing second ink A was changed to 52.9 mass %.

[0135] <Preparation of second ink L> Second ink L was prepared by mixing the components in the same manner as second ink A, except that the amount of urethane resin emulsion A used in preparing second ink A was changed to 29.8 mass %.

[0136] <Preparation of second ink M> The urethane resin emulsion A used in preparing the second ink A was changed to urethane resin emulsion B, and the amount added was changed to 23.8% by mass. In addition, the amount of propylene glycol added was changed to 10.0% by mass. Apart from these two changes, the components were mixed in the same manner as in the second ink A to prepare second ink M.

[0137] <Preparation of second ink N> The urethane resin emulsion A used in preparing the second ink A was changed to urethane resin emulsion B, and the amount added was changed to 42.3% by mass. In addition, the amount of propylene glycol added was changed to 10.0% by mass. Apart from these two changes, the components were mixed in the same manner as in the second ink A to prepare second ink N.

[0138] The formulations of the second inks A to N are shown in Tables 1 and 2.

[0139] [Table 1]

[0140] [Table 2]

[0141] (intermediate transfer body) The surface free energy τ of the intermediate transfer member must be 20 mN / m or more and 40 mN / m or less in order to improve the wettability of the first ink and the second ink and the releasability of the recorded image. The intermediate transfer members used in the examples are shown in Table 3 below. The layer structure of the intermediate transfer members used in the examples is a single layer, and this layer is made using the material shown in the column for substrate in Table 2.

[0142] [Table 3]

[0143] (Examples 1 to 16, Comparative Examples 1 to 8) The following evaluations were carried out. Images were formed using the image-forming apparatus 1 shown in FIG. 1. The results are shown in Table 4.

[0144] <Transferability> The first ink was ejected onto the surface of the intermediate transfer body, and after heating and drying at the drying temperature shown in the table, the second ink was ejected and dried to form an intermediate image. The formed intermediate image and a recording medium (plain paper, manufactured by Canon) were pressed together with a roller and heated at 120°C to transfer the intermediate image to the recording medium. The image density (OD) of the image, which had been left standing at room temperature for 24 hours after transfer, was measured using an xRite (manufactured by PANTONE). The printing conditions were 600 x 600 dpi. Evaluation was performed according to the following evaluation criteria. ○ indicates pass, and △ and × indicate fail.

[0145] [Evaluation criteria] ○: 1.6 or more △: 1.5 or more and less than 1.6 ×: Less than 1.5

[0146] <Image fixation> The first ink was ejected onto the surface of the intermediate transfer body, and after heating and drying at the drying temperature shown in the table, the second ink was ejected and dried to form an intermediate image. The formed intermediate image and a recording medium (plain paper, manufactured by Canon) were pressed together with a roller and heated at 120°C to transfer the intermediate image to the recording medium. The transferred image was rubbed with a metal duster using a Gakushin tester (device name: dyed material rubbing fastness tester, manufactured by Intec) under conditions of a load of 200 gf and 25 rubs. The image density (OD) of the image transferred to the metal duster was measured using an xRite (manufactured by PANTONE). Evaluation was performed according to the following evaluation criteria. Average or better is practical.

[0147] [Evaluation criteria] ○: Less than 0.15 △: 0.15 or more and less than 0.28 ×:0.28 or more

[0148] [Table 4]

[0149] As can be seen from the evaluation results, the examples included in the present invention, in a method of transferring an intermediate image from an intermediate transfer body to a recording medium, can transfer the intermediate image well even to a recording medium with an uneven surface, and achieve good fixation. The comparative examples not included in the present invention are unable to simultaneously satisfy both good transferability and good fixability.

[0150] For example, aspects of the present invention are as follows. <1> a first ejection means for ejecting a first ink onto the intermediate transfer body; a first heating unit for heating the intermediate transfer body onto which the first ink has been ejected; a second ejection means for ejecting a second ink onto the intermediate transfer body heated by the first heating means; a second heating unit for heating the intermediate transfer body onto which the second ink has been ejected; a transfer unit that brings the intermediate transfer body heated by the second heating unit into contact with a recording medium, heats and presses the intermediate transfer body, and transfers the intermediate image formed on the intermediate transfer body to the recording medium, the first ink includes a first resin; the second ink includes a second resin; the surface free energy of the intermediate transfer member is 20 mN / m or more and 40 mN / m or less; The first heating means and the second heating means perform heating at 120°C or higher and 160°C or lower, The glass transition temperature of the first resin is higher than the glass transition temperature of the second resin. An image forming apparatus characterized by: <2> the first ink contains at least the first resin, water, an organic solvent, a surfactant, and a colorant; The second ink contains at least the second resin, water, an organic solvent, and a surfactant, and does not contain a colorant. Characterized by <1> 2. The image forming apparatus according to claim 1 . <3> The rate of weight reduction of the first ink and the second ink due to heating by the first heating means and heating by the second heating means is 70% or more and 90% or less. Characterized by <1> or <2> 2. The image forming apparatus according to claim 1 . <4> The solid content of the second resin contained in the second ink is 10% by mass or more and 15% by mass or less. Characterized by <1> from <3> 10. The image forming apparatus according to claim 9, wherein <5> The second resin is a urethane resin. Characterized by <1> from <4> 10. The image forming apparatus according to claim 9, wherein <6> The transfer unit performs transfer by raising the temperature of the intermediate transfer body above the glass transition point of the first resin. Characterized by <1> from <5> 10. The image forming apparatus according to claim 9, wherein <7> The intermediate transfer member contains ethylene propylene diene rubber. Characterized by <1> from <6> 10. The image forming apparatus according to claim 9, wherein <8> The transfer means has a thermal transfer roller and an opposing roller facing the thermal transfer roller, and thermal transfer is performed by passing the intermediate transfer body and the recording medium through a nip formed by the thermal transfer roller and the opposing roller. Characterized by <1> from <7> 10. The image forming apparatus according to claim 9, wherein <9> a first ejection step of ejecting a first ink onto an intermediate transfer body; a first heating step of heating the intermediate transfer body onto which the first ink has been ejected; a second ejection step of ejecting a second ink onto the intermediate transfer body heated in the first heating step; a second heating step of heating the intermediate transfer body onto which the second ink has been ejected; a transfer step of contacting the intermediate transfer body heated in the second heating step with a recording medium, and applying heat and pressure to the intermediate transfer body, thereby transferring the intermediate image formed on the intermediate transfer body to the recording medium, the first ink includes a first resin; the second ink includes a second resin; the surface free energy of the intermediate transfer member is 20 mN / m or more and 40 mN / m or less; The first heating step and the second heating step are performed at a temperature of 120°C or higher and 160°C or lower, The glass transition temperature of the first resin is higher than the glass transition temperature of the second resin. An image forming method comprising: [Explanation of symbols]

[0151] 1. Image forming device 2 First Head 3, 4 heater 5 Second Head 6 Opposing roller 7 Conveyor roller 9 Fuser roller 10 Intermediate transfer belt 11 Recording media [Prior art documents] [Patent documents]

[0152] [Patent Document 1] Japanese Patent Application Publication No. 62-92849 [Patent Document 2] Japanese Patent Application Publication No. 1-226336

Claims

1. a first ejection means for ejecting a first ink onto the intermediate transfer body; a first heating unit for heating the intermediate transfer body onto which the first ink has been ejected; a second ejection means for ejecting a second ink onto the intermediate transfer body heated by the first heating means; a second heating unit for heating the intermediate transfer body onto which the second ink has been ejected; a transfer unit that brings the intermediate transfer body heated by the second heating unit into contact with a recording medium, heats and presses the intermediate transfer body, and transfers the intermediate image formed on the intermediate transfer body to the recording medium, the first ink includes a first resin; the second ink includes a second resin; the surface free energy of the intermediate transfer member is 20 mN / m or more and 40 mN / m or less; The first heating means and the second heating means perform heating at a temperature of 120°C or higher and 160°C or lower, The glass transition temperature of the first resin is higher than the glass transition temperature of the second resin. An image forming apparatus characterized by:

2. the first ink contains at least the first resin, water, an organic solvent, a surfactant, and a colorant; The second ink contains at least the second resin, water, an organic solvent, and a surfactant, and does not contain a colorant.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. The rate of weight reduction of the first ink and the second ink due to heating by the first heating means and heating by the second heating means is 70% or more and 90% or less.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

4. The solid content of the second resin contained in the second ink is 10% by mass or more and 15% by mass or less.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. The second resin is a urethane resin.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

6. The transfer unit performs transfer by raising the temperature of the intermediate transfer body above the glass transition point of the first resin.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

7. The intermediate transfer member contains ethylene propylene diene rubber.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

8. The transfer means has a thermal transfer roller and an opposing roller facing the thermal transfer roller, and thermal transfer is performed by passing the intermediate transfer body and the recording medium through a nip formed by the thermal transfer roller and the opposing roller.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. a first ejection step of ejecting a first ink onto an intermediate transfer body; a first heating step of heating the intermediate transfer body onto which the first ink has been ejected; a second ejection step of ejecting a second ink onto the intermediate transfer body heated in the first heating step; a second heating step of heating the intermediate transfer body onto which the second ink has been ejected; a transfer step of contacting the intermediate transfer body heated in the second heating step with a recording medium, and applying heat and pressure to the intermediate transfer body, thereby transferring the intermediate image formed on the intermediate transfer body to the recording medium, the first ink includes a first resin; the second ink includes a second resin; the surface free energy of the intermediate transfer member is 20 mN / m or more and 40 mN / m or less; The first heating step and the second heating step are performed at a temperature of 120°C or higher and 160°C or lower, The glass transition temperature of the first resin is higher than the glass transition temperature of the second resin. An image forming method comprising:

Images