Image forming method, ink set, and image forming apparatus

Abstract

To provide an image forming method by which the transferability of an intermediate image from an intermediate transfer body is good and an image excellent in transfer density and character sharpness can be formed on a recording medium.SOLUTION: An image forming method comprising a pretreatment liquid application step of applying a pretreatment liquid onto an intermediate transfer member, an aqueous ink application step of applying an aqueous ink onto the pretreatment liquid applied onto the intermediate transfer member, a drying step of drying the pretreatment liquid and the aqueous ink on the intermediate transfer member, and a thermal transfer step of thermally transferring an intermediate image formed on the intermediate transfer member to a recording medium, wherein the following conditions (1) to (4) are satisfied: (1) The Shore A hardness of the surface layer of the intermediate transfer member is 80 or less. (2) The contact angle of the intermediate transfer member with respect to the pretreatment liquid is 40 ° or less 1.5 seconds after contact with the liquid. (3) The contact angle of the intermediate transfer body with respect to the aqueous ink is 40° or less after 1.5 seconds of liquid contact. (4) The surface tensions of the pre-treatment liquid and the aqueous ink at the bubble lifetime 1500msec are 22mN / m or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Water-based inks are widely used as inks for inkjet recording methods. A conventional technique using water-based inks is a so-called transfer type image recording method in which an ink image, which is an intermediate image, is formed on a transfer body and then transferred to a recording medium to record the image.

[0003] For example, Patent Document 1 discloses an inkjet recording method for recording an image on a recording medium using aqueous ink. In this inkjet recording method, an intermediate transfer body made of silicone rubber or fluororubber with high releasability is used, and because the intermediate transfer body has high releasability and is not wetted by a pretreatment liquid or aqueous ink, a step of hydrophilizing the surface of the intermediate transfer body by plasma treatment is provided.

[0004] According to Patent Document 1, it is possible to provide an image forming method, an image forming apparatus, an intermediate transfer body used in the image forming method, and a surface modification method for the intermediate transfer body, which are capable of forming high-quality ink images on various recording media by achieving both high ink image retention on the intermediate transfer body and high transferability of the ink image from the intermediate transfer body. Summary of the Invention [Problem to be solved by the invention]

[0005] In the inkjet recording method proposed in Patent Document 1, silicone rubber or fluororubber, which has high releasability, is used for the intermediate transfer body. However, since the intermediate transfer body has such high releasability that the pretreatment liquid and the water-based ink do not wet the intermediate transfer body, a step of performing a plasma treatment on the surface of the intermediate transfer body to make it hydrophilic is provided. However, the image forming method proposed in Patent Document 1 requires a relatively large plasma processing device. In addition, frequent irradiation of the intermediate transfer body with plasma causes deterioration of the intermediate transfer body, which reduces the image transferability, and therefore requires replacement of the intermediate transfer body.

[0006] Therefore, an object of the present invention is to provide an image forming method and an image forming apparatus that can form an image on a recording medium that has good transferability of an intermediate image from an intermediate transfer body, excellent transfer density and character sharpness, and excellent beading in solid image areas. [Means for solving the problem]

[0007] The image forming method of the present invention for solving the above problems is as follows. a pretreatment liquid application step of applying a pretreatment liquid onto the intermediate transfer body; a water-based ink applying step of applying a water-based ink onto the pretreatment liquid applied onto the intermediate transfer body; a drying step of drying the pretreatment liquid and the aqueous ink on the intermediate transfer body; a thermal transfer step of thermally transferring the intermediate image formed on the intermediate transfer body onto a recording medium; Including, An image forming method characterized by satisfying the following conditions (1) to (4): (1) The surface layer of the intermediate transfer member has a Shore A hardness of 80 or less. (2) The contact angle of the intermediate transfer member with respect to the pretreatment liquid is 40° or less after 1.5 seconds of contact with the liquid. (3) The contact angle of the intermediate transfer member with respect to the water-based ink is 40° or less after 1.5 seconds of contact with the ink. (4) The surface tension of the pretreatment liquid and the aqueous ink is 22 mN / m or less when the bubble lifetime is 1500 msec. [Effects of the Invention]

[0008] According to the present invention, an image forming method and an image forming apparatus can be provided that have good transferability of an intermediate image from an intermediate transfer body, are excellent in transfer density and character sharpness, and are capable of forming an image on a recording medium that is excellent in beading in solid image areas. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of a chart printed using an image forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0010] The image forming method and image forming apparatus 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 within the scope of the present invention.

[0011] <Image forming method and image forming apparatus> The image forming method of the present invention includes a pretreatment liquid applying step of applying a pretreatment liquid onto an intermediate transfer body, an aqueous ink applying step of applying an aqueous ink onto the pretreatment liquid applied onto the intermediate transfer body, a drying step of drying the pretreatment liquid and the aqueous ink on the intermediate transfer body, and a thermal transfer step of thermally transferring an intermediate image formed on the intermediate transfer body onto a recording medium. The pretreatment liquid has a function of wetting the intermediate transfer body and contains a reactant that reacts with the water-based ink.

[0012] The image forming apparatus of the present invention includes an intermediate transfer body, a pretreatment liquid applying means for applying a pretreatment liquid onto the intermediate transfer body, an aqueous ink applying means for applying an aqueous ink onto the pretreatment liquid applied onto the intermediate transfer body, a drying means for drying the pretreatment liquid and the aqueous ink on the intermediate transfer body, and a thermal transfer means for thermally transferring an intermediate image formed on the intermediate transfer body to a recording medium. The pretreatment liquid has a function of wetting the intermediate transfer body and contains a reactant that reacts with the water-based ink.

[0013] To transfer an intermediate image formed on an intermediate transfer body using aqueous ink to a recording medium, the intermediate transfer body and the recording medium are superimposed and heated. This heating softens the intermediate image, allowing it to be transferred to the recording medium. During this transfer, the intermediate image may not be transferred to the recording medium due to factors such as the type of resin contained in the aqueous ink and the surface energy value of the intermediate transfer body. Even if the intermediate image is transferred to the recording medium, there may be areas of the image formed on the recording medium that are not transferred (whiteouts), and fine text may be difficult to read, resulting in poor sharpness.

[0014] The present inventors have conducted extensive research and have arrived at the present invention, which enables the transfer of an intermediate image from an intermediate transfer member to a recording medium with good transfer density and character sharpness, and with excellent beading in solid image areas.

[0015] The image forming method and image forming apparatus of the present invention will be described in detail below. The intermediate transfer member may be referred to as an intermediate transfer substrate, a transfer member, etc. The image forming apparatus may be referred to as a forming apparatus, etc. The image forming method may be referred to as a forming method, etc. The pretreatment liquid mainly functions to thicken the pigment and resin particles contained in the aqueous ink and to wet the intermediate transfer substrate with the aqueous ink. The aqueous ink is sometimes simply referred to as ink. The recording medium to which the intermediate image is transferred is sometimes referred to as a recorded matter, a printed matter, etc.

[0016] Fig. 1 is a schematic diagram showing one embodiment of an image forming apparatus of the present invention. The image forming apparatus 300 shown in Fig. 1 produces a recorded product by transferring an intermediate image 310 to a recording medium 311 via an intermediate transfer member 301. Such an image forming apparatus may also be called a transfer-type image forming apparatus.

[0017] The image forming apparatus 300 includes a pretreatment liquid ejection device 302, an ink ejection device 303, an intermediate transfer body 301, a drying device 305A, a drying device 305B, a heat roller 306, a cleaning roller 307, and the like.

[0018] Intermediate transfer body 301 is supported by drive rollers 309A and 309C and platen roller 309B as support members, and is transported in the direction of the black arrow in the figure. The transport of intermediate transfer body 301 may also be referred to as movement, rotation, etc. In this example, intermediate transfer body 301 is a belt-like member and may also be referred to as an intermediate transfer belt, etc.

[0019] The pretreatment liquid ejection device 302 is an example of a pretreatment liquid application unit, and ejects the pretreatment liquid onto the intermediate transfer body 301. The pretreatment liquid mainly has a function of making the intermediate transfer body 301 more wettable and contains a reactant that reacts with the water-based ink.

[0020] This pretreatment liquid must be able to wet the surface layer of the intermediate transfer body 301, especially the silicone rubber and fluororubber, in order to form a beautiful image on the intermediate transfer body, so it is necessary to lower the surface tension of the pretreatment liquid.It was found that image formation is difficult unless the dynamic surface tension of the pretreatment liquid (bubble lifetime 1500 msec) is 22 mN / m or less. A particularly preferred range is 18 N / m or more and 22 mN / m or less, and an especially preferred range is 18 mN / m or more and 21 mN / m or less.

[0021] Furthermore, even if the dynamic surface tension bubble lifetime 1500 msec value for only the aqueous ink is set to 22 mN / m or less, a clear image cannot be formed on the intermediate transfer body 301. Therefore, by setting the dynamic surface tension bubble lifetime 1500 msec values ​​for both the pretreatment liquid and the aqueous ink to 22 mN / m or less, it became possible to form a clear image on the silicone rubber and fluororubber surface layers of the intermediate transfer body 301.

[0022] The ink ejection device 303 is an example of an ink applying unit, and ejects aqueous ink. In this example, when the aqueous ink applying units 303K, 303C, 303M, and 303Y are described without distinction, they will be referred to as ejection device 303. The aqueous ink applying units are not limited to the example shown in the figure, and the number and type can be changed as appropriate.

[0023] The water-based ink ejected onto the intermediate transfer body 301 reacts with the pretreatment liquid on the intermediate transfer body 301 .

[0024] In this example, the ink ejecting device 303 continuously ejects water-based ink onto the pretreatment liquid ejecting device 302. As shown in the figure, the pretreatment liquid ejecting device 302 and the ink ejecting device 303 may be disposed adjacent to each other, or may be disposed at a distance from each other.

[0025] The drying device 305A and the drying device 305B are examples of the drying means, and dry the intermediate transfer body 301 onto which the pretreatment liquid and the aqueous ink have been ejected. In this manner, an intermediate image 310 is formed on the intermediate transfer body 301. In the drawing, intermediate images 310K, 310C, and 310Y are shown as examples. When describing the black, cyan, magenta, and yellow intermediate images without distinction, they may be referred to as the intermediate image 310. The drying device 305B and the drying device 305 may also be referred to as a post-drying device, etc.

[0026] The heat roller 306 and platen roller 309B are an example of a transfer means, and thermally transfer the intermediate image 310 on the intermediate transfer body 301 to the recording medium 311. In this example, the heat roller 306 and platen roller 309B form a nip portion, and the conveyed intermediate transfer body 301 and recording medium 311 are passed through the nip portion, and the intermediate image 310 is transferred to the recording medium 311 while being heated and pressurized. As a result, a transferred image 312 is formed on the recording medium 311, and a recorded product is produced. The transferred image 312 may also be simply referred to as an image.

[0027] In this example, the recording medium 311 is conveyed and passes through the nip portion. The white arrow in the figure indicates the conveying direction of the recording medium 311.

[0028] After transfer, the cleaning roller 307 cleans the intermediate transfer body 301. For example, the cleaning roller 307 cleans the intermediate image 310 remaining on the intermediate transfer body 301. The cleaning roller 307 faces a cleaning opposing roller 308, for example.

[0029] The following describes the main parts of the image forming apparatus of this embodiment: [1] intermediate transfer body, [2] support member, [3] pretreatment liquid ejection device, [4] aqueous ink ejection device, [5] post-drying device, [6] thermal transfer, [7] recording medium, [8] recording medium transport device, and [9] cleaning device.

[0030] [1] Intermediate transfer body The intermediate transfer body 301 has, for example, a surface layer on the outermost surface, on which an intermediate image is formed. The surface layer is preferably made of a material with high releasability in order to improve transferability of the intermediate image to a recording medium.

[0031] When transferring the intermediate image, if the intermediate image and the recording medium are configured to be in surface contact with each other, a nipped state can be maintained. During this time, the intermediate image is efficiently heated, improving transferability. For this reason, it is preferable to use an intermediate transfer member that can be efficiently heated.

[0032] The intermediate transfer body 301 may have a surface layer and a substrate formed of an elastic material, or alternatively, the substrate may be provided with a polyamide film and a polyimide film in addition to the surface layer.

[0033] Suitable materials for the surface layer include highly elastic elastomer materials such as natural rubber and synthetic rubber; polyolefin resins such as polyethylene and polypropylene; ethylene propylene diene diene rubber (EPDM), silicone rubber, fluorosilicone rubber, phenylsilicone rubber, and fluororubber, with silicone rubber and fluororubber being particularly preferred. The substrate to be laminated with the surface layer is preferably a polyethylene terephthalate film, a polyamide film or a polyimide film, and particularly preferably a polyimide film which has high heat resistance.

[0034] When an infrared heater or the like is used as a pre-drying device described later, it is preferable to blend an infrared absorbing material such as carbon black into the material constituting the surface layer. In this case, the irradiated infrared rays are more easily converted into heat, thereby improving heating efficiency.

[0035] The intermediate transfer member may further have a reinforcing layer. By having the reinforcing layer, when the intermediate transfer member is attached to a support member, lateral stretching can be suppressed and stiffness can be maintained. The reinforcing layer may be provided, for example, on or under the elastic layer. The reinforcing layer may be made of a material with a high compressive elastic modulus, such as a woven fabric.

[0036] The layers constituting the intermediate transfer member (for example, the surface layer, the substrate, and the reinforcing layer) can be bonded to each other using, for example, an adhesive or double-sided tape. The size of the intermediate transfer member can be freely selected according to the recording speed and image size. The intermediate transfer member may be in the form of, for example, a sheet, a roller, a belt, or an endless web.

[0037] [2] Support member The intermediate transfer body 301 is supported by a support member. In this example, the support members are drive rollers 309A, 309B, and 309C, but are not limited to these and can be changed as appropriate. The intermediate transfer body may be wound around the support member in the form of a belt, for example. When wound around the support member, it is preferable that the support member has a certain degree of structural strength from the viewpoints of transport accuracy and durability.

[0038] Examples of materials for the support member include metal, ceramic, and resin. Among these, it is preferable to use metal materials such as stainless steel and aluminum. By using metal materials, it is possible to improve the responsiveness of control by reducing inertia during operation, in addition to providing rigidity and dimensional accuracy that can withstand stress during transfer.

[0039] [3] Pretreatment liquid discharge device and pretreatment liquid discharge process The image forming apparatus 300 includes a pretreatment liquid ejection device 302 that ejects a pretreatment liquid onto an intermediate transfer body 301 . As described above, the pretreatment liquid ejected onto the intermediate transfer body 301 mainly has the function of wetting the intermediate transfer body and the function of a pretreatment liquid containing a reactant that reacts with the water-based ink, and a beautiful intermediate transfer image can be formed by applying the pretreatment liquid to the intermediate transfer body 301. The ejection process by the pretreatment liquid ejection device is referred to as a pretreatment liquid application process.

[0040] The location where the pretreatment liquid is ejected can be selected as appropriate. The pretreatment liquid is preferably applied to an area on the intermediate transfer body 301 that is larger than the area where the water-based ink is applied, and more preferably to an area that is slightly larger than the area where the water-based ink is applied. This allows the intermediate transfer image to be formed neatly.

[0041] This configuration will be described again. The area of ​​the pretreatment liquid ejected onto the intermediate transfer body by the pretreatment liquid ejection means is preferably larger than the area of ​​the aqueous ink ejected onto the intermediate transfer body by the aqueous ink ejection means. This configuration will be described again from the perspective of an image forming method. The area of ​​the pretreatment liquid ejected onto the intermediate transfer body in the pretreatment liquid ejection step is preferably larger than the area of ​​the aqueous ink ejected onto the intermediate transfer body in the aqueous ink ejection step.

[0042] The pretreatment liquid ejected onto the intermediate transfer body 301 forms a layer on the intermediate transfer body 301. In order to efficiently form a thin layer of the pretreatment liquid on the surface of the intermediate transfer body 301, for example, it is preferable to do the following.

[0043] The pretreatment liquid contains, for example, a reactant that aggregates components having anionic groups, such as resins and pigment dispersions in the aqueous ink. The components contained in the pretreatment liquid can be appropriately selected, and preferably contain, for example, one or more selected from inorganic acid salts, organic acid salts, and cationic polymers, water, and an organic solvent. In this case, the pretreatment liquid has excellent ejection properties and is easy to aggregate the aqueous ink.

[0044] Detailed examples of the pretreatment liquid are described in more detail below in the section "Pretreatment Liquid."

[0045] As the pretreatment liquid ejection device 302 and the water-based ink ejection device 303, for example, a liquid ejection head such as an inkjet head can be used.

[0046] The amount of pretreatment liquid applied (adhered) to the intermediate transfer body 301 varies depending on the type of the intermediate transfer body 301 and the recording medium 311. However, from the viewpoint of improving image quality and drying properties, it is set to 0.1 g / m 2 More than 500g / m 2 It is preferable that the content is less than 1 g / m 2 More than 400g / m 2 In addition, when a fabric is used as the recording medium 311, it is more preferable that the density is 100 g / m or less. 2 More than 500g / m 2Preferably, it is 200 g / m or less. 2 More than 500g / m 2 More preferably, it is 300 g / m or less. 2 More than 400g / m 2 It is more preferable that:

[0047] [4] Water-based ink ejection device and water-based ink ejection process The image forming apparatus 300 has an aqueous ink ejection device 303 (second ejection means) that ejects aqueous ink onto the intermediate transfer body 301. The ink ejected by the aqueous ink ejection device 303 reacts with the pretreatment liquid upon contact with the pretreatment liquid. The ejection process by the aqueous ink ejection device is referred to as the aqueous ink ejection process.

[0048] As shown in the figure, for example, the image forming apparatus 300 has water-based ink ejection devices 303K, 303C, 303M, and 303Y, which enable water-based inks of black, cyan, magenta, and yellow to be applied onto the intermediate transfer body 301. The inks to be ejected are not limited to these, and white ink, transparent ink, etc. may also be used. Detailed examples of water-based inks will be described later.

[0049] [5] Post-drying equipment and post-drying process The post-drying device is a drying device that dries the aqueous ink after it has been ejected, and is an example of the drying means described above. The drying means that dries the aqueous ink after it has been ejected may also be referred to as the post-drying means. The post-drying device corresponds to the drying device 305B and the drying device 305C in this example. The post-drying device may also be referred to as the post-drying means, and the drying by the post-drying device may also be referred to as the post-drying process. Both the drying device 305B and the drying device 305C may be used, or either one may be used.

[0050] The post-drying device can be appropriately selected, and examples thereof include a system in which heating is performed from the front surface direction, a system in which heating is performed from the back surface direction, and a system in which these systems are combined.

[0051] The drying means of the post-drying device is preferably a method (non-contact method) that does not directly contact the aqueous ink layer, etc. Examples of such non-contact drying methods include a hot air heating mechanism using a dryer, a radiation heating mechanism using a halogen heater or an infrared heater, and a heating mechanism using electromagnetic induction.

[0052] The drying temperature of the post-drying means (drying means) can be selected appropriately.

[0053] [6] Thermal transfer The image forming apparatus 300 includes a transfer unit that thermally transfers an intermediate image 310 on an intermediate transfer body 301 to a recording medium 311. As the transfer unit in this embodiment, for example, a heat fixing mechanism used in an electrophotographic image forming apparatus can be used.

[0054] As a transfer means, for example, a method can be used in which a nip is formed using two opposing rotating bodies, an intermediate transfer body 301 and a recording medium 311 are passed through the nip, and an intermediate image 310 on the intermediate transfer body 301 is brought into contact with the recording medium 311 and transferred. In this case, a heating mechanism is provided on at least one of the two rotating bodies. This method is also called a contact heat fixing method, and with this method, the intermediate image 310 can be efficiently transferred to the recording medium 311.

[0055] 1 uses a contact heat fixing method, and the transfer means in this example has two opposing rotating bodies: a heat roller 306 (thermal transfer roller) and a platen roller 309B. Because the platen roller 309B faces the heat roller 306, it is also called an opposing roller. The heat roller 306 and the platen roller 309B form a nip portion, and the intermediate transfer body 301 and the recording medium 311 are passed through the nip portion, and the intermediate image 310 is brought into contact with the recording medium 311 and thermally transferred.

[0056] In this embodiment, the transfer means performs thermal transfer at a temperature equal to or higher than the softening point of the resin contained in the aqueous ink. By performing thermal transfer at a temperature equal to or higher than the softening point of the resin contained in the aqueous ink, at least a portion of the resin melts, further improving the releasability of the intermediate image 310 and improving transferability. If the thermal transfer temperature is lower than the softening point of the resin, transfer may not be performed well.

[0057] The transfer means has a heat roller 306 and an opposing roller (platen roller 309B) that faces the heat roller 306, and thermal transfer is performed by passing the intermediate transfer body 301 and recording medium 311 through the nip portion formed by the heat roller 306 and the platen roller 309B, and it is preferable that the temperature when passing through the nip portion is 100°C or higher.

[0058] The temperature when passing through the nip refers to the surface temperature of image 312 (transferred image) immediately after passing through the nip. The surface temperature of image 312 immediately after passing through the nip can be measured using a non-contact thermometer (for example, trade name "IT-314" (manufactured by AS ONE)). Due to the influence of the latent heat of moisture in the image and the heat capacity of heat roller 306, the surface temperature of image 312 and the temperature of heat roller 306 do not necessarily coincide.

[0059] It is believed that heating during thermal transfer reduces the water content of the ink aggregates that make up the aqueous ink layer, resulting in large structures that adhere closely together and exhibit structural viscosity. Therefore, the ink viscosity is high when the shear rate is high, and the ink layer on the convex portions of the recording medium is more likely to be pushed into the concave portions by the transfer device, making it less likely to produce blank spots. On the other hand, when the shear rate is low, the ink viscosity decreases, making it more likely to be pushed into the concave portions by the transfer device, making it more likely to produce blank spots. Furthermore, many intermediate transfer members have a heat resistance of 200°C or less. From this perspective, it is preferable to set the thermal transfer temperature in the range of 100 to 200°C.

[0060] From the viewpoint of transport accuracy of the intermediate transfer body 301 and durability, it is preferable that the platen roller 309C has an appropriate structural strength. Examples of materials for the platen roller 309C include metal, ceramic, resin, etc. Among these, a metal member wrapped with elastic rubber is preferred, as it not only has the rigidity and dimensional accuracy to withstand the stresses that occur during transfer, but also reduces inertia during operation and improves control responsiveness.

[0061] The heat roller 306 may be, for example, a roller member incorporating a heat source such as a halogen heater. The heat roller 306 may have a layer structure that uses, for example, an elastic layer and a surface layer.

[0062] The thermal transfer temperature of the thermal transfer means varies depending on conditions such as the temperature of the heat roller 306, nip width, nip time, and environmental temperature. In this embodiment, the thermal transfer temperature of the thermal transfer means can be determined based on the surface temperature of the image after it has passed through the nip portion. The surface temperature of image 312 can also be said to be the maximum temperature of the surface portion of the image that comes into contact with heat roller 306. The temperature of the portion of intermediate image 310 that is heated by heat transfer from heat roller 306 rises, and the heated portion of the image reaches its maximum when it passes through the nip portion.

[0063] As described above, the transfer means can use the contact heat fixing method of the fixing device used in the electrophotographic system. An example of the case where the contact heat fixing method is used in this embodiment will be described below.

[0064] In thermal transfer using the contact heat fixing method, the intermediate image 310 on the intermediate transfer body 301 is brought into contact with the recording medium 311, and liquid components contained in the intermediate image 310 are dried and removed. In thermal transfer, the intermediate transfer body 301 and the recording medium 311 are brought into contact and sandwiched between two rotating bodies for heat fixing, thereby increasing the adhesive strength of the aqueous ink layer and improving the abrasion resistance of the image. Furthermore, if the aqueous ink contains resin particles, for example, heat fixing tends to melt the resin particles and further increase the adhesive strength of the aqueous ink layer.

[0065] As described above, the transfer unit in this embodiment uses, for example, a heat roller 306 and a platen roller 309B as two rotating bodies. A nip portion is formed between the heat roller 306 and the platen roller 309B, through which the intermediate transfer body 301 and the recording medium 311 pass. As the recording medium 311, transported by the transport unit, and the intermediate transfer body 301, transported by the support member, pass through the nip portion, the recording medium 311 comes into contact with and is pressed against the intermediate image 310 on the intermediate transfer body 301, and the intermediate image 310 is heated. This allows the intermediate image 310 to be thermally transferred to the recording medium 311. In this contact heat fixing method, it may be said that the intermediate image 310 is fixed to the recording medium 311, or that the intermediate image 310 is thermally transferred to the recording medium 311.

[0066] In the example described in this embodiment, a heat roller 306 is used, but this is not limiting and an endless belt stretched between two rollers can also be used. In this case, thermal transfer can be performed by using a heating mechanism that heats the endless belt.

[0067] The transfer means may apply pressure to the intermediate transfer body 301 and the recording medium 311 when performing thermal transfer. The pressure to be applied is not particularly limited as long as it is sufficient to transfer heat from the transfer means to the image. The pressure to be applied is, for example, 1 kgf / cm 2 More than 20kgf / cm 2 It is preferable to set it to 3 kgf / cm or less. 2 More than 5kgf / cm2 It is more preferable that the pressure applied to the image by the transfer means can be measured with a surface thickness distribution measuring device (for example, the product name "I-SCAN" (manufactured by Nitta)).

[0068] [7] Recording medium Any known recording medium can be used as the recording medium 311. Examples of the recording medium include a long object wound into a roll, or a sheet cut to a predetermined size. Examples of materials constituting the recording medium include paper such as coated paper or plain paper, plastic or metal films, wood boards, and cardboard.

[0069] [8] Recording medium transport device The recording medium 311 is conveyed by a conveying means, for example, in the direction of the white arrow in the figure. The conveying means can be composed of, for example, a recording medium feed roller and a recording medium take-up roller. The conveying speed of the recording medium 311 is preferably determined taking into consideration the speed required in each process.

[0070] [9] Cleaning equipment and cleaning process The image forming apparatus 300 of this example has, as a cleaning device, a cleaning roller 307 and a cleaning opposing roller 308. The cleaning device may be called a cleaning means or a cleaning device. The cleaning performed by the cleaning device is called a cleaning process.

[0071] The cleaning device cleans the intermediate transfer body 301, for example, by removing ink remaining on the intermediate transfer body 301. The cleaning device performs cleaning by sandwiching the intermediate transfer body 301 between a cleaning roller 307 and a cleaning counter roller 308, for example.

[0072] The cleaning device cleans the intermediate transfer body 301 after thermal transfer and before ejecting the pretreatment liquid. As shown in the figure, the cleaning device (e.g., cleaning roller 307) is provided downstream of the transfer means (e.g., heat roller 306) and upstream of the pretreatment liquid ejection device 302 in the transport direction of the intermediate transfer body 301.

[0073] The cleaning device may clean the intermediate transfer body 301 using a cleaning liquid. The cleaning liquid is not particularly limited, and may contain an organic solvent or may be an aqueous cleaning liquid. A cleaning liquid supply unit for supplying the cleaning liquid may be provided. The cleaning device may use a member such as a web in addition to a roller.

[0074] By cleaning the intermediate transfer body with a cleaning device, it is possible to prevent deterioration in image quality.

[0075] A member for removing the cleaning liquid remaining on the intermediate transfer body 301 after cleaning may be provided. By removing the cleaning liquid remaining on the intermediate transfer body, it is possible to more effectively prevent deterioration of image quality. Methods for removing the cleaning liquid remaining on the intermediate transfer body include, for example, blade removal, brush removal, and liquid absorption by an absorbent. Among these, it is preferable to remove the cleaning liquid remaining on the intermediate transfer body by liquid absorption by an absorbent.

[0076] (Ink and ink set) A detailed example of the water-based ink will be described below. The pretreatment liquid and the water-based ink may be collectively referred to as an ink set. The water-based ink may be simply referred to as ink.

[0077] The aqueous ink used in the present invention contains, for example, water, a coloring material, a resin, an organic solvent, and, if necessary, a surfactant, other components (A), etc. The aqueous ink is, for example, a color ink, but may also be a white ink, etc.

[0078] In this specification, the term "ink set" refers to a set in which the pretreatment liquid and the aqueous ink are present in an independent state. For example, the ink set is not limited to a set in which the first container that contains the pretreatment liquid and the second container that contains the aqueous ink are manufactured, sold, etc., in an integrated state.

[0079] <Colorant> The coloring material is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include pigments. As the pigment, for example, inorganic pigments and organic pigments can be used. These may be used alone or in combination of two or more. Furthermore, examples of the pigment that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments, and metallic pigments (gold, silver, etc.).

[0080] The inorganic pigment is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, carbon black, etc. Among these, titanium oxide is preferred as a white coloring material, and carbon black is preferred as a black coloring material.

[0081] The carbon black is not particularly limited and can be appropriately selected depending on the purpose. Examples of the carbon black include channel black, furnace black, gas black, and lamp black produced by known methods such as a contact method, a furnace method, and a thermal method.

[0082] The organic pigment is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, aniline black, etc. Among these, the organic pigment is preferably an azo pigment or a polycyclic pigment. Examples of the azo pigment include azo lake, insoluble azo pigment, condensed azo pigment, and chelate azo pigment. Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Examples of the dye chelate include basic dye chelates and acid dye chelates.

[0083] Specific examples of the organic pigment include CI Pigment Yellow 1, CI Pigment Yellow 3, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 17, CI Pigment Yellow 24, CI Pigment Yellow 34, CI Pigment Yellow 35, CI Pigment Yellow 37, CI Pigment Yellow 42 (Yellow Iron Oxide), CI Pigment Yellow 53, CI Pigment Yellow 55, CI Pigment Yellow 74, CI Pigment Yellow 81, CI Pigment Yellow 83, CI Pigment Yellow Yellow 95, CI Pigment Yellow 97, CI Pigment Yellow 98, CI Pigment Yellow 100, CI Pigment Yellow 101, CI Pigment Yellow 104, CI Pigment Yellow 108, CI Pigment Yellow 109, CI Pigment Yellow 110, CI Pigment Yellow 117, CI Pigment Yellow 120, CI Pigment Yellow 128, CI Pigment Yellow 139, CI Pigment Yellow 150, CI Pigment Yellow 151, CI Pigment Yellow Pigment Yellow 155, CI Pigment Yellow 153, CI Pigment Yellow 180, CI Pigment Yellow 183, CI Pigment Yellow 185, CI Pigment Yellow 213; CI Pigment Orange 5, CI Pigment Orange 13, CI Pigment Orange 16, CI Pigment Orange 17, CI Pigment Orange 36, CI Pigment Orange 43, CI Pigment Orange 51; CI Pigment Red 1, CI Pigment Red 2, CI Pigment Red Red 3, CI Pigment Red 5, CI Pigment Red 17, CI Pigment Red 22, CI Pigment Red 23, CI Pigment Red 31, CI Pigment Red 38, CI Pigment Red 48:2 (Permanent Red 2B (Ca)), CI Pigment Red 48:3, CI Pigment Red 48:4, CI Pigment Red 49:1, CI Pigment Red 52:2, CI Pigment Red 53:1, CI Pigment Red 57:1 (Brilliant Carmine 6B), CIPigment Red 60:1, CI Pigment Red 63:1, CI Pigment Red 63:2, CI Pigment Red 64:1, CI Pigment Red 81, CI Pigment Red 83, CI Pigment Red 88, CI Pigment Red 101 (Red Foot), CI Pigment Red 104, CI Pigment Red 105, CI Pigment Red 106, CI Pigment Red 108 (Cadmium Red), CI Pigment Red 112, CI Pigment Red 114, CI Pigment Red 122 (Quinacridone Magenta), CI Pigment Red 123, CI Pigment Red 146, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 168, CI Pigment Red 170, CI Pigment Red 172, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 179, CI Pigment Red 185, CI Pigment Red 190, CI Pigment Red 193, CI Pigment Red 209, CI Pigment Red 194, CI Pigment Red 195, CI Pigment Red 196, CI Pigment Red 197, CI Pigment Red 198, CI Pigment Red 209, CI Pigment Red 199, CI Pigment Red 210, CI Pigment Red 211, CI Pigment Red 212, CI Pigment Red 213, CI Pigment Red 214, CI Pigment Red 215, CI Pigment Red 216, CI Pigment Red 217, CI Pigment Red 218, CI Pigment Red 219, CI Pigment Red 220, CI Pigment Red 221, CI Pigment Red 222, CI Pigment Red 223, CI Pigment Red 224, CI Pigment Red 225, CI Pigment Red 226, CI Pigment Red 227, CI Pigment Red 228, CI Pigment Red 229, CI Pigment Red 230, CI Pigment Red 231, CI Pigment Red 232, CI Pigment Red 233, Pigment Red 219; CI Pigment Violet 1 (Rhodamine Lake), CI Pigment Violet 3, CI Pigment Violet 5:1, CI Pigment Violet 16, CI Pigment Violet 19, CI Pigment Violet 23, CI Pigment Violet 38; CI Pigment Blue 1, CI Pigment Blue 2, CI Pigment Blue 15 (Phthalocyanine Blue), CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3 (Phthalocyanine Blue), CI Pigment Blue 15:4, CI Pigment Blue 16, CI Pigment Blue 17:1, CI Pigment Blue 56, CI Pigment Blue 60, CI Pigment Blue 63; CI Pigment Green 1, CI Pigment Green 4, CI Pigment Green 7, CI Pigment Green 8, CI Pigment Green 10, CI Pigment Green 17, CI Pigment Green 18, CI Pigment Green 36, etc.

[0084] The BET specific surface area of ​​the pigment is not particularly limited and can be appropriately selected depending on the purpose. 2 / g or more 1,500m 2 / g or less is preferable, and 20m 2 / g or more 600m 2 / g or less is more preferable, and 50m 2 / g or more 300m 2 / g or less is more preferable.

[0085] A pigment having a desired BET specific surface area can be obtained by a general size reduction or pulverization treatment. The size reduction or pulverization treatment is not particularly limited and can be appropriately selected from known methods, such as ball mill pulverization, jet mill pulverization, and ultrasonic treatment. The pigment may be subjected to one type of treatment alone or a combination of two or more types of treatments.

[0086] The cumulative 50% volume particle diameter D50 of the pigment is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably 50 nm or more and 350 nm or less in the ink.

[0087] The content (solid content) of the pigment is not particularly limited and can be set appropriately depending on the purpose, but is preferably 1.0% by mass or more and 15.0% by mass or less, and more preferably 1.5% by mass or more and 10.0% by mass or less, based on the total amount of the ink. A pigment content (solid content) of 1.0% by mass or more based on the total amount of the ink is preferred because it improves the color development and image density of the ink. A pigment content (solid content) of 15.0% by mass or less based on the total amount of the ink is preferred because it improves the ejection stability of the ink.

[0088] As the pigment in the present invention, a composite pigment may be used. As the composite pigment, from the viewpoint of small average primary particle diameter, silica / carbon black composite material (manufactured by Toda Kogyo Co., Ltd.), silica / phthalocyanine PB15:3 composite material (manufactured by Toda Kogyo Co., Ltd.), silica / disazo yellow composite material (manufactured by Toda Kogyo Co., Ltd.), and silica / quinacridone PR122 composite material (manufactured by Toda Kogyo Co., Ltd.) are preferred.

[0089] For example, if inorganic pigment particles with a primary particle diameter of 20 nm are coated with an equal amount of organic pigment, the primary particle diameter of this composite pigment will be approximately 25 nm. If an appropriate dispersant can be used to disperse these particles down to the primary particle size, it will be possible to produce a very fine composite pigment dispersion ink with a dispersed particle diameter of 25 nm. In this composite pigment, the organic pigment on the surface that coats it contributes to dispersion, but the properties of the inorganic pigment at the center also appear through a thin layer of organic pigment about 2.5 nm thick, so both It is also necessary to select a pigment dispersant that can simultaneously stabilize the dispersion of the pigment.

[0090] The aqueous ink may contain a resin, such as a urethane resin. From the viewpoint of reaction with the aqueous ink, it is preferable that at least one selected from the urethane resin and the coloring material is anionic. That is, it is preferable that the coloring material is anionic, and it is more preferable that the coloring material is an anionic pigment.

[0091] Examples of the anionic pigment include surfactant-dispersed pigments in which a pigment is dispersed in a surfactant, resin-dispersed pigments in which a pigment is dispersed in a resin, resin-coated dispersed pigments in which the surface of a pigment is coated with a resin, and self-dispersed pigments in which hydrophilic groups are provided on the surface of the pigment. In any of these dispersion forms, it is preferable that the pigments are water-dispersible.

[0092] When the anionic pigment is the resin-coated dispersed pigment or the self-dispersed pigment, it preferably has at least one hydrophilic group on the pigment surface. Examples of the hydrophilic group include -COOM, -SO3M, -PO3HM, -PO3M2, -CONM2, -SO3NM2, -NH-CH4-COOM, -NH-CH4-SO3M, -NH-CH4-PO3HM, -NH-CH4-PO3M2, -NH-CH4-CONM2, and -NH-CH4-SO3NM2. These hydrophilic groups can be introduced by known methods. Note that "M" in the hydrophilic group represents a counter ion.

[0093] The counter ion represented by "M" in the hydrophilic group is preferably a quaternary ammonium ion. Specific examples of the quaternary ammonium ion include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, benzyltrimethylammonium ion, benzyltriethylammonium ion, and tetrahexylammonium ion. Among these, tetraethylammonium ion, tetrabutylammonium ion, and benzyltrimethylammonium ion are preferred, and tetrabutylammonium ion is more preferred.

[0094] Inks using such pigments have excellent storage stability and suppress an increase in viscosity when water evaporates. This is presumably because the hydrophilic group containing the quaternary ammonium ion allows the pigment dispersion to be kept stable even when the water evaporates from the water-rich ink and the ink becomes organic solvent-rich.

[0095] As the anionic pigment other than the colorant having a hydrophilic group on its surface, a polymer emulsion in which the pigment is contained in polymer fine particles is preferred from the viewpoint of storage stability of the ink. In the polymer emulsion, the pigment may be encapsulated in the polymer fine particles or adsorbed on the surface of the polymer fine particles. In this case, it is not necessary for all of the pigment to be encapsulated in the polymer fine particles or adsorbed on the surface of the polymer fine particles, and a portion of the pigment may be dispersed in the emulsion.

[0096] Examples of polymers for the polymer particles include vinyl polymers, polyester polymers, and polyurethane polymers, among which vinyl polymers and polyester polymers are preferred. These may be used alone or in combination of two or more.

[0097] The mass ratio of the coloring material to the organic solvent is preferably adjusted appropriately because it affects the ink ejection stability, suppression of adhesion of waste ink in the maintenance mechanism of the image forming apparatus, etc. For example, when an ink having a high content of the coloring material but a low content of the organic solvent is ejected from an inkjet head, evaporation of water near the ink meniscus of the nozzle may progress, resulting in ejection defects.

[0098] <Resin> The water-based ink may contain a resin, and preferably contains resin particles. Examples of resin particles include polyurethane dispersions and styrene-acrylic resin dispersions.

[0099] <<Other resins>> The ink may contain other resins in addition to the resin particles. The other resins are not particularly limited and can be selected appropriately depending on the purpose, but resins that have excellent film-forming properties and solvent resistance, water resistance, and weather resistance are useful in image formation. Examples of such resins include condensation-based synthetic resins, addition-based synthetic resins, and natural polymers. Examples include child compounds. These may be used alone or in combination of two or more.

[0100] Examples of the condensation synthetic resin include polyester resin, polyepoxy resin, polyad resin, polyether resin, poly(meth)acrylic resin, acrylic-silicone resin, and fluorine-based resin. In this specification, "(meth)acrylic" means acrylic or methacrylic. Examples of the addition-based synthetic resin include polyolefin resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyvinyl ester-based resins, polyacrylic acid-based resins, and unsaturated carboxylic acid-based resins. Examples of the natural polymer compounds include celluloses, rosins, and natural rubber.

[0101] The content of the other resins is not particularly limited as long as it does not impair the effects of the present invention, and can be set appropriately depending on the purpose. The other resins may be appropriately synthesized or commercially available. Examples of commercially available products of the other resins include the following: Superflex 150HS (polyurethane dispersion, Tg: 32°C, volume average particle size: 80 nm, solid content: 38% by mass, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Takelac® W-6061 (polyurethane dispersion, Tg: 25°C, volume average particle size: 100 nm, solid content: 30% by mass, manufactured by Mitsui Chemicals, Inc.) Boncoat VF1060 (acrylic emulsion, Tg: -10°C, solids content: 50% by mass, manufactured by DIC Corporation)

[0102] <White ink> By forming a white image on a recording medium, the white ink functions, for example, as a base layer for a color image formed by the color inks applied to the area where the white ink is applied, thereby improving the color development of the color image. In this specification, "white" refers to a color commonly referred to as white or off-white, and includes colors that are slightly colored.

[0103] The Hunter whiteness of the white image formed on the recording medium with the white ink is not particularly limited and can be appropriately selected depending on the purpose, but is preferably not less than 75, more preferably not less than 80, and particularly preferably not less than 85. When the Hunter whiteness of the white image is 75 or more, the color development of the color image can be improved.

[0104] The method for measuring the Hunter whiteness is not particularly limited and can be appropriately selected depending on the purpose. For example, the color values ​​L, a, and b of a white image formed on a recording medium can be measured using a spectrodensitometer (for example, X-rite eXact, manufactured by X-Rite), and the Hunter whiteness can be calculated using the following calculation formula (1). Note that L, a, and b are color representation methods established by the International Commission on Illumination (CIE), and are also referred to as "L*," "a*," and "b*." can be. Hunter Whiteness = 100 - sqr [(100 - L) 2 +(a 2 +b 2 )]...Calculation formula (1)

[0105] In this specification, the term "color ink" refers to a liquid composition that forms a color image. When the color ink and the white ink are used in combination, the liquid composition may form a color image by applying the color ink to an area where the white ink has been applied. In this specification, the term "color" refers to a color that is not included in the "white" category, and includes, for example, black, cyan, magenta, and yellow.

[0106] <Water> The water is not particularly limited and can be appropriately selected depending on the purpose. Examples include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, and ultrapure water. These may be used alone or in combination of two or more.

[0107] The water content is not particularly limited and can be set appropriately depending on the purpose. From the viewpoint of the drying property and ejection reliability of the ink, the water content is preferably 10.0% by mass or more and 90.0% by mass or less, and more preferably 20.0% by mass or more and 60.0% by mass or less, of the total amount of the ink.

[0108] <Organic solvents> The organic solvent is not particularly limited and can be appropriately selected depending on the purpose. However, it is preferable to use an organic solvent having an equilibrium moisture content of 30% by mass or more in an environment of 23°C and 80% relative humidity (RH) (hereinafter, sometimes referred to as a "humectant"). Among these, it is more preferable for the organic solvent to have a boiling point (bp) of 245°C to 290°C and an equilibrium moisture content of 43% to 49% by mass. The selection of such an organic solvent is related to the suppression of color bleeding and beading (in other words, the control of static surface tension and dynamic surface tension), but also to the improvement of ink ejection stability and the suppression of waste ink adhesion in the maintenance mechanism of the image forming apparatus.

[0109] Here, the "equilibrium moisture content" is calculated using the following formula (2): a saturated aqueous solution of potassium chloride and sodium chloride mixed in a ratio of 6:4 (potassium chloride:sodium chloride, parts by mass) was used, and the temperature and humidity inside the desiccator was kept at 23°C ± 1°C and 80% ± 3% RH. Petri dishes containing 1 g of each organic solvent were stored in the desiccator, and the equilibrium moisture content was measured. Equilibrium moisture content (mass%) = [amount of moisture absorbed by organic solvent / (amount of organic solvent + amount of moisture absorbed by organic solvent)] × 100... Calculation formula (2)

[0110] Examples of the humectant include polyhydric alcohols having an equilibrium moisture content of 30% by mass or more in an environment at 23° C. and 80% RH. Specific examples of the polyhydric alcohol include diethylene glycol (bp 245° C., equilibrium moisture content 43% by mass), triethylene glycol (bp 285° C., equilibrium moisture content 39% by mass), tetraethylene glycol (bp 324° C. to 330° C., equilibrium moisture content 37% by mass), 1,3-butanediol (bp 203° C. to 204° C., equilibrium moisture content 35% by mass), glycerin (bp 290° C., equilibrium moisture content 49% by mass), diglycerin (bp 270° C. / 15 mmHg, equilibrium moisture content 38% by mass), 1,2,3-butanetriol (bp 175° C. / 27 mmHg, equilibrium moisture content 38% by mass), and 1,2,4-butanetriol (bp 190° C. to 191° C. / 18 mmHg, equilibrium moisture content 41% by mass). Among these, glycerin and 1,3-butanediol are preferred. These may be used alone or in combination of two or more.

[0111] Examples of wetting agents other than the polyhydric alcohols include 2-methyl-1,3-butanediol (bp 214°C), 3-methyl-1,3-butanediol (bp 203°C), dipropylene glycol (bp 232°C), 1,5-pentanediol (bp 242°C), propylene glycol (bp 187°C), 2-methyl-2,4-pentanediol (bp 197°C), ethylene glycol (bp 196°C to 198°C), and tripropylene glycol. Examples of suitable olefin copolymers include ethylene glycol (bp 267°C), hexylene glycol (bp 197°C), polyethylene glycol (viscous liquid to solid), polypropylene glycol (bp 187°C), 1,6-hexanediol (bp 253°C to 260°C), 1,2,6-hexanetriol (bp 178°C), trimethylolethane (solid, melting point (mp) 199°C to 201°C), and trimethylolpropane (solid, (mp) 61°C). These may be used alone or in combination of two or more.

[0112] The content of the organic solvent is not particularly limited and can be set appropriately depending on the purpose, but is preferably 10.0% by mass or more and 75.0% by mass or less, and more preferably 15.0% by mass or more and 50.0% by mass or less, based on the total amount of the ink. An organic solvent content of 10.0% by mass or more based on the total amount of the ink is preferable because it provides a good moisturizing effect for the ink. An organic solvent content of 75.0% by mass or less based on the total amount of the ink is preferable because it improves the drying properties of the ink on a recording medium, as described below.

[0113] In addition, when the recording medium described later is non-permeable (low permeable), the organic solvent is preferably an organic solvent having a solubility parameter (SP value) of 9.0 (cal / cm 3 ) 1 / 2 More than 11.8(cal / cm 3 ) 1 / 2 It is preferable to use an organic solvent having an SP value in the above range. A specific example of an organic solvent having an SP value in the above range is 3-ethyl-3-oxetanemethanol (SP value: 11.31 (cal / cm 3 ) 1 / 2 ), 3-methyl-3-oxetanemethanol (SP value: 11.79 (cal / cm 3 ) 1 / 2 ), β-methoxy-N,N-dimethylpropionamide (3-methoxy-N,N-dimethylpropionamide) (SP value: 9.19 (cal / cm 3 ) 1 / 2 ), β-butoxy-N,N-dimethylpropionamide (3-butoxy-N,N-dimethylpropionamide) (SP value: 9.03 (cal / cm 3 ) 1 / 2 ), 1,2-hexanediol (SP value: 11.8 (cal / cm 3 ) 1 / 2 ), 2-ethyl-1,3-hexanediol (SP value: 10.6 (cal / cm 3 ) 1 / 2 ), 2,2,4-trimethyl-1,3-pentanediol (SP value: 10.8 (cal / cm 3 ) 1 / 2 ), diethylene glycol monoethyl ether (SP value: 10.14 (cal / cm 3 )1 / 2 ), 3-methoxy-1-butanol (SP value: 9.64 (cal / cm 3 ) 1 / 2 ), 3-methoxy-3-methyl-1-butanol (SP value: 9.64 (cal / cm 3 ) 1 / 2 ), 3-methyl-1,5-pentanediol (SP value: 11.8 (cal / cm 3 ) 1 / 2 ), methyl propylene glycol (SP value: 9.43 (cal / cm 3 ) 1 / 2 ), diethylene glycol mono-n-butyl ether (SP value: 9.86 (cal / cm 3 ) 1 / 2 ), diethylene glycol monomethyl ether (SP value: 10.34 (cal / cm 3 ) 1 / 2 ), triethylene glycol monomethyl ether (SP value: 10.12 (cal / cm 3 ) 1 / 2 ), propylene glycol monopropyl ether (SP value: 9.82 (cal / cm 3 ) 1 / 2 ), propylene glycol monomethyl ether (SP value: 10.19 (cal / cm 3 ) 1 / 2 ), propylene glycol monobutyl ether (SP value: 9.69 (cal / cm 3 ) 1 / 2 ), 3-methoxy-1-butanol (SP value: 10.65 (cal / cm 3 ) 1 / 2 ), 3-methoxy-1-propanol (SP value: 10.41 (cal / cm 3 ) 1 / 2 ), and dipropylene glycol monomethyl ether (SP value: 9.84 (cal / cm 3 ) 1 / 2 ) etc.

[0114] Furthermore, when the recording medium described below is non-permeable (low-permeable), the content of the organic solvent having an SP value in the above range is not particularly limited and can be set appropriately depending on the purpose. However, from the viewpoint of suppressing color bleeding and beading (in other words, controlling static surface tension and dynamic surface tension) and from the viewpoint of the color development properties of the ink, the content is preferably 0.5% by mass or more and 5.0% by mass or less, and more preferably 1.0% by mass or more and 4.0% by mass or less, of the total amount of the ink.

[0115] <Surfactant> The aqueous ink preferably contains a surfactant from the viewpoint of suppressing color bleeding and beading (in other words, controlling static surface tension and dynamic surface tension). Examples of the surfactant include acetylene-based surfactants, silicone-based surfactants, and fluorine-based surfactants. Specific examples of the acetylene-based surfactants include acetylene glycol compounds and acetylene alcohol compounds. Specific examples of the silicone-based surfactants include polyether-modified siloxane compounds. Specific examples of the fluorine-based surfactants include fluorine compounds. Among these, polyether-modified siloxane compounds are preferred from the viewpoint of improving filter liquid permeability and friction fastness. These may be used alone or in combination of two or more.

[0116] The ink used in the present invention preferably contains a surfactant, which makes it difficult for the ink to wet the ink-repellent film on the nozzle plate of the inkjet head, thereby preventing ejection defects caused by the ink adhering to the nozzle and improving ejection stability.

[0117] The polyether-modified siloxane compound is preferably one represented by the following general formulas (1) to (4).

[0118] [ka]

[0119] In the general formula (1), R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m represents an integer of 0 to 23, n represents an integer of 1 to 10, a represents an integer of 1 to 23, and b represents an integer of 0 to 23.

[0120] [ka]

[0121] In the general formula (2), R2 and R3 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m represents an integer of 1 to 8, and c and d each independently represent an integer of 1 to 10.

[0122] [ka]

[0123] In the general formula (3), R4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and e represents an integer of 1 to 8.

[0124] [ka]

[0125] In the general formula (4), R5 represents a polyether group of the following general formula (5), and f represents an integer of 1 to 8.

[0126] [ka]

[0127] In the general formula (5), R6 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and g represents 0 to 23, and h represents an integer from 0 to 23. However, there is no case where g and h are 0 at the same time.

[0128] Specific examples of the compound represented by the general formula (1) include compounds represented by the following structural formulas (1) to (8).

[0129] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0130] Specific examples of the compound represented by the general formula (2) include compounds represented by the following structural formula (9).

[0131] [ka]

[0132] Specific examples of the compound represented by the general formula (3) include compounds represented by the following structural formula (10).

[0133] [ka]

[0134] Specific examples of the compound represented by the general formula (4) include compounds represented by the following structural formulas (11) to (13).

[0135] [ka] [ka] [ka]

[0136] The polyether-modified siloxane compound may be suitably synthesized or may be a commercially available product. Commercially available polyether-modified siloxane compounds include, for example, KF-353, KF-640, KF-642, KF-643, and KF-644 (all manufactured by Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5051 (manufactured by Nihon Emulsion Co., Ltd.), BYK-345, BYK-347, BYK-348, BYK-375, BYK-377, and BYK-3451 (manufactured by BYK-Chemie Japan KK), Silface SAG002, Silface SAG003, Silface SAG005, Silface SAG503A, Silface SAG021, and Silface SAG008 (manufactured by Nissin Chemical Industry Co., Ltd.), TEGO Wet KL245, TEGO Wet 250, TEGO Wet 260, TEGO Wet 265, TEGO Wet 270, and TEGO Wet 280 (both manufactured by Evonik Japan Co., Ltd.) Among these, KF-353 (manufactured by Shin-Etsu Chemical Co., Ltd.) is preferred from the viewpoint of improving filter liquid permeability and friction fastness.

[0137] The acetylene glycol compound and the acetylene alcohol compound are not particularly limited and can be appropriately selected depending on the purpose. The acetylene glycol compound and the acetylene alcohol compound may be appropriately synthesized or may be commercially available. Commercially available examples of the acetylene glycol compound and the acetylene alcohol compound include Surfynol 104E (2,4,7,9-tetramethyl-5-decyne-4,7-diol), Surfynol 420, Surfynol 440, Surfynol 465, Surfynol SE, Surfynol SE-F, Surfynol PSA-336, Surfynol DF110D, Surfynol DF58, Olfine E1004, Olfine E1010, Olfine E1020, Olfine PD-001, Olfine PD-002W, Olfine PD-004, Olfine PD-005, Olfine EXP. 4001, Olfine EXP. 4200, Olfine EXP. 4123, and Olfine EXP. 4300 (all manufactured by Nissin Chemical Industry Co., Ltd.).

[0138] The fluorine compound is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of low foaming properties, 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 on the side chains are preferred.

[0139] Examples of the perfluoroalkylsulfonic acid compound include perfluoroalkylsulfonic acid and perfluoroalkylsulfonate salts. Examples of the perfluoroalkyl carboxylic acid compound include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylates. Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group on the side chain include sulfate ester salts of polyoxyalkylene ether polymers having a perfluoroalkyl ether group on the side chain, and salts of polyoxyalkylene ether polymers having a perfluoroalkyl ether group on the side chain.

[0140] The counter ion of the salt in the fluorine compound is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include Li, Na, K, NH, NH, NH(CHCHOH), and NH(CHCHOH).

[0141] The fluorine compound may be synthesized appropriately or may be a commercially available product. Examples of commercially available fluorine compounds include Surflon S-242, Surflon S-243, Surflon S-420, and Surflon S-431 (all manufactured by AGC Seimi Chemical Co., Ltd.); Megafac F-251, Megafac F-430, Megafac F-444, Megafac F-477, Megafac F-552, Megafac F-553, and Megafac F-554 (all manufactured by DIC Corporation); CAPSTONE FS-10, CAPSTONE FS-30, CAPSTONE FS-31, CAPSTONE FS-34, CAPSTONE FS-35, CAPSTONE FS-51, CAPSTONE FS-60, CAPSTONE FS-61, CAPSTONE FS-63, CAPSTONE FS-64, CAPSTONE FS-65, and CAPSTONE FS-10. FS-3100 (all manufactured by Chemours Corporation); Ftergent 212M, Ftergent 215M, Ftergent 250, Ftergent 251, Ftergent 222F, Ftergent 245F (all manufactured by Neos Corporation); Polyfox PF-136A, PF-156A, PF-151N (all manufactured by Kitamura Chemical Industries Co., Ltd.). Among these, CAPSTONE FS-3100 and CAPSTON FS-34 manufactured by DuPont, Ftergent 250 and Ftergent 251 manufactured by Neos Corporation, and Polyfox PF-151N manufactured by Kitamura Chemical Industries Co., Ltd. are preferred in terms of achieving good print quality, particularly significant improvements in color development, paper penetration, wettability, and dye leveling.

[0142] The content of the surfactant is not particularly limited and can be set appropriately depending on the purpose, but is preferably 0.001% by mass or more and 5.0% by mass or less, and more preferably 0.01% by mass or more and 3.0% by mass or less, based on the total amount of the ink. A surfactant content of 0.001% by mass or more based on the total amount of the ink is preferable because it is easy to obtain the effect of suppressing color bleeding and beading (in other words, control of static surface tension and dynamic surface tension). Note that if the surfactant content exceeds 5.0% by mass based on the total amount of the ink, the effect may become saturated.

[0143] <Other ingredients> The other component (A) is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include additives.

[0144] <<Additives>> The additives are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include foam inhibitors (antifoaming agents), pH adjusters, antiseptic and antifungal agents, chelating agents, rust inhibitors, antioxidants, ultraviolet absorbers, oxygen absorbers, and light stabilizers.

[0145] -Foam suppressor (defoaming agent)- The foam inhibitor is added in a small amount to the ink to suppress foaming of the ink. Here, "foaming" refers to a liquid forming a thin film that encloses air. The generation of this foam is related to the properties of the ink, such as the surface tension and viscosity. That is, a liquid with high surface tension, such as water, is resistant to foaming because of the force that tries to minimize the surface area of ​​the liquid. In contrast, ink with high viscosity and high permeability is prone to foaming because of its low surface tension, and the generated foam is easily maintained due to the viscosity of the solution, making it difficult to eliminate. Typically, a foam suppressor destroys foam by locally lowering the surface tension of the foam film, or by dotting the foam surface with a foam suppressor that is insoluble in the foaming liquid.

[0146] When the ink of the present invention contains a polyether-modified siloxane compound as a surfactant, the foam inhibitor is preferably a foam inhibitor containing a compound represented by the following general formula (6).

[0147] [ka]

[0148] In the general formula (6), R7 and R8 each independently represent an alkyl group having 3 to 6 carbon atoms, and R9 and R 10 each independently represents an alkyl group having 1 to 2 carbon atoms, and n represents an integer of 1 to 6.

[0149] Although the foam suppressor containing the compound represented by the general formula (6) does not have as strong an effect of reducing surface tension as the polyether-modified siloxane compound, it has high compatibility with the polyether-modified siloxane compound. Therefore, the foam suppressor is efficiently incorporated into the foam film, and the difference in surface tension between the polyether-modified siloxane compound and the foam suppressor is thought to cause the surface of the foam film to become locally unbalanced, resulting in the destruction of the foam.

[0150] Examples of the compound represented by the general formula (6) include 2,4,7,9-tetramethyldecane-4,7-diol and 2,5,8,11-tetramethyldodecane-5,8-diol. Among these, 2,5,8,11-tetramethyldodecane-5,8-diol is preferred due to its high anti-foaming effect and compatibility with ink.

[0151] The content of the anti-foaming agent is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 0.01% by mass or more and 10.0% by mass or less, and more preferably 0.1% by mass or more and 5.0% by mass or less, relative to the total amount of the ink. A content of the anti-foaming agent of 0.01% by mass or more relative to the total amount of the ink is preferable because it provides a good anti-foaming effect. A content of the anti-foaming agent of 10.0% by mass or less relative to the total amount of the ink can suppress any effects on ink properties such as the particle size of the resin particles.

[0152] - pH adjuster - The pH adjuster is not particularly limited as long as it can adjust the pH of the ink, and can be appropriately selected depending on the purpose, and examples thereof include alcohol amines, hydroxides of alkali metal elements, hydroxides of ammonium, phosphonium hydroxides, and carbonates of alkali metals. Among these, alcohol amines are preferred. These may be used alone or in combination of two or more.

[0153] Examples of the alcohol amines include diethanolamine, triethanolamine, and 2-amino-2-ethyl-1,3-propanediol. Examples of the hydroxides of alkali metal elements include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the hydroxide of ammonium include ammonium hydroxide and quaternary ammonium hydroxide. Examples of the phosphonium hydroxide include quaternary phosphonium hydroxide. Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

[0154] The content of the pH adjuster is not particularly limited as long as it can adjust the ink to a desired pH, and can be set appropriately depending on the purpose.

[0155] -Preservative and fungicidal agent- The antiseptic and antifungal agent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include 1,2-benzothiazolin-3-one, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, and sodium pentachlorophenol. These may be used alone or in combination of two or more. The content of the antiseptic and antifungal agent is not particularly limited as long as it does not impair the effects of the present invention, and can be appropriately set depending on the purpose.

[0156] The antiseptic and antifungal agent may be suitably synthesized or may be a commercially available product. Examples of commercially available antiseptic and antifungal agents include PROXEL (registered trademark) GXL (antiseptic and antifungal agent whose main ingredient is 1,2-benzothiazolin-3-one, manufactured by Avecia, contains 20% of the ingredients and dipropylene glycol).

[0157] -Chelating reagents- The chelating agent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate. These may be used alone or in combination of two or more. The content of the chelating agent is not particularly limited as long as it does not impair the effects of the present invention, and can be appropriately set depending on the purpose.

[0158] -Rust inhibitor- The rust inhibitor is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite. These may be used alone or in combination of two or more. The content of the rust inhibitor is not particularly limited as long as it does not impair the effects of the present invention, and can be set appropriately depending on the purpose.

[0159] -Antioxidants- The antioxidant is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include phenol-based antioxidants (including hindered phenol-based antioxidants), amine-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. These may be used alone or in combination of two or more. The content of the antioxidant is not particularly limited as long as it does not impair the effects of the present invention, and can be appropriately set depending on the purpose.

[0160] -Ultraviolet absorber- The ultraviolet absorber is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and nickel complex salt-based ultraviolet absorbers. These may be used alone or in combination of two or more. The content of the ultraviolet absorber is not particularly limited as long as it does not impair the effects of the present invention, and can be appropriately set depending on the purpose.

[0161] <Ink properties> The physical properties of the aqueous ink of the present invention are not particularly limited and can be appropriately set depending on the purpose. For example, it is preferable that the viscosity, surface tension, pH, etc. are within the following ranges.

[0162] The viscosity of the ink at 25° C. is preferably 5 mPa·s or more and 25 mPa·s or less, and more preferably 6 mPa·s or more and 20 mPa·s or less. When the viscosity of the ink at 25° C. is 5 mPa·s or more, it is preferable because it can improve image density and character quality. Furthermore, it is preferable that the viscosity of the ink at 25° C. is 25 mPa·s or less, since this can improve the ejection stability of the ink. The viscosity can be measured using, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) Measurement conditions are 25°C, a standard cone rotor (1°34' x R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.

[0163] From the viewpoint of ensuring that the ink is suitably leveled on the intermediate transfer body and forming a beautiful image, the surface tension of the ink is preferably 22 mN / m or less, and more preferably 21 mN / m or less, in terms of dynamic surface tension at 25°C and a bubble lifetime of 1500 msec.

[0164] The pH of the ink is preferably 7 to 12 from the viewpoint of improving the ejection stability of the ink. Here, the pH can be measured at 25°C using, for example, a pH meter (HM-30R type, manufactured by DKK-Toa Corporation).

[0165] <Ink manufacturing method> The ink can be produced by stirring and mixing the above-mentioned materials, and this can be done using equipment such as a sand mill, a homogenizer, a ball mill, a paint shaker, or an ultrasonic disperser.

[0166] <Ink composition analysis method> The composition of the ink of the present invention can be analyzed using a gas chromatograph mass spectrometer (GC-MS, manufactured by Shimadzu Corporation), a TG / DTA simultaneous measurement device, or the like.

[0167] (Pretreatment liquid) Next, a detailed example of the pretreatment liquid will be described. In order to distinguish the components contained in the pretreatment liquid from the components contained in the aqueous ink, the components contained in the pretreatment liquid that are the same as the components contained in the aqueous ink will be indicated with the symbol "(2)".

[0168] The pretreatment liquid is a liquid composition that is applied to the intermediate transfer body before the application of the aqueous ink (ink). By applying the pretreatment liquid before the application of the ink, the ink that is applied later can be coagulated and thickened, thereby improving adhesion.

[0169] The pretreatment liquid contains a reactant that reacts with the water-based ink (ink). The pretreatment liquid contains, for example, water and a reactant (flocculant), and may also contain, as necessary, a resin (2), a wax (2), an organic solvent (2), a surfactant (2), and other components (B).

[0170] The pretreatment liquid preferably contains, for example, at least one selected from inorganic acid salts, organic acid salts, and cationic polymers, water, and an organic solvent, which can ensure reactivity with ink and ejection stability.

[0171] <Water> The water is not particularly limited and can be appropriately selected depending on the purpose. For example, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, and ultrapure water can be used.

[0172] The water content is not particularly limited and can be set appropriately depending on the purpose. From the viewpoint of the drying property of the pretreatment liquid, the water content is preferably 10.0% by mass or more and 90.0% by mass or less, and more preferably 20.0% by mass or more and 60.0% by mass or less, based on the total amount of the pretreatment liquid.

[0173] <Reactant (flocculant)> The pretreatment liquid contains a reactant that reacts with the aqueous ink (ink). The reactant may also be referred to as an aggregating agent. In this specification, the term "aggregating agent" refers to a component that aggregates or thickens the ink when the pretreatment liquid comes into contact with the ink. Specific examples include components that aggregate anionic compounds (e.g., colorants or urethane resins) contained in the ink. By using a pretreatment liquid containing such an aggregating agent, the ink that comes into contact with the pretreatment liquid can be aggregated or thickened, thereby improving the adhesion of the ink to the surface of a recording medium.

[0174] The reactant (flocculant) may be, for example, one or more selected from inorganic acid salts, organic acid salts, and cationic polymers. The flocculant is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include cationic compounds. The cationic compound is preferably, for example, any one selected from inorganic metal salts, organic acid metal salts, organic acid ammonium salts, and cationic polymers, and more preferably any one selected from inorganic metal salts and cationic polymers. These may be used alone or in combination of two or more.

[0175] Examples of the inorganic metal salts include magnesium sulfate, aluminum sulfate, manganese sulfate, nickel sulfate, iron (II) sulfate, copper (II) sulfate, zinc sulfate, iron (II) nitrate, iron (III) nitrate, cobalt nitrate, strontium nitrate, copper (II) nitrate, nickel (III) nitrate, and the like. Examples of inorganic metal salts include lead(II) nitrate, manganese(II) nitrate, nickel(II) chloride, calcium chloride, tin(II) chloride, strontium chloride, barium chloride, magnesium chloride, sodium sulfate, potassium sulfate, lithium sulfate, sodium hydrogen sulfate, potassium hydrogen sulfate, sodium nitrate, potassium nitrate, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium chloride, and potassium chloride. Among these, magnesium sulfate and potassium chloride are preferred as the inorganic metal salt.

[0176] Examples of the organic acid metal salts include sodium L-aspartate, magnesium L-aspartate, calcium ascorbate, sodium L-ascorbate, sodium succinate, disodium succinate, aluminum citrate, potassium citrate, calcium citrate, tripotassium citrate, trisodium citrate, disodium citrate, zinc lactate, aluminum lactate, potassium lactate, calcium lactate, sodium lactate, magnesium lactate, calcium acetate, potassium tartrate, calcium tartrate, DL-sodium tartrate, and potassium sodium tartrate.

[0177] The inorganic metal salt and the organic acid metal salt are preferably selected from calcium salts, magnesium salts, nickel salts, and aluminum salts, respectively, and are therefore suitable in that the aggregating effect on the urethane resin contained in the ink is improved, the occurrence of color bleeding and beading can be further suppressed, and the storage stability of the pretreatment liquid can be improved.

[0178] Examples of the organic acid ammonium salts include ammonium acetate, ammonium propionate, ammonium lactate, ammonium oxalate, ammonium tartrate, ammonium succinate (diammonium succinate), diammonium malonate, diammonium hydrogen citrate, triammonium citrate, and ammonium L-glutamate.

[0179] The cationic polymer is preferably a quaternary ammonium salt type cationic polymer compound, such as a dialkylallylammonium chloride polymer, a dialkylaminoethyl (meth)acrylate quaternary ammonium salt polymer, a modified polyvinyl alcohol dialkylammonium salt polymer, and a dialkyldiallylammonium salt polymer. In addition to the above-mentioned examples, other cationic polymers that may be used include cationic specially modified polyamine compounds, cationic polyamide polyamine compounds, cationic urea-formalin resin compounds, cationic polyacrylamide compounds, cationic alkyl ketene dimers, cationic dicyandiamide compounds, cationic dicyandiamide-formalin condensation compounds, cationic dicyandiamide-polyamine condensation compounds, cationic polyvinyl formamide compounds, cationic polyvinyl pyridine compounds, cationic polyalkylene polyamine compounds, and cationic epoxy polyamide compounds. Among these, the compounds represented by the following general formulas (7) to (10) are preferred.

[0180] [ka]

[0181] In the general formula (7), R 11 each independently represents a methyl group or an ethyl group, Y - represents a halogen ion, and n represents an integer.

[0182] [ka]

[0183] In the general formula (8), Y - represents a halogen ion, a nitrate ion, a nitrite ion, or an acetate ion, and R 12 represents H or CH3, R 13 , R 14 , and R 15 each independently represents a hydrogen atom or an alkyl group, and n represents an integer.

[0184] [ka]

[0185] In the general formula (9), R 16each independently represents a methyl group or an ethyl group, Y - represents a halogen ion, a nitrate ion, a nitrite ion, or an acetate ion, and n represents an integer.

[0186] [ka]

[0187] In the general formula (10), Y - represents a halogen ion, a nitrate ion, a nitrite ion, or an acetate ion; X represents a halogen atom; n represents an integer of 1 to 3; and m represents an integer of 1 to 3.

[0188] The content of the coagulant is not particularly limited and can be set appropriately depending on the purpose. From the viewpoint of the solubility of the coagulant and the like, and from the viewpoint of suppressing the occurrence of color bleeding and beading, the content is preferably from 0.1% by mass to 30.0% by mass, and more preferably from 1.0% by mass to 20.0% by mass, relative to the total amount of the pretreatment liquid.

[0189] <Resin (2)> In this specification, the resin contained in the pretreatment liquid may be referred to as "resin (2)." Note that this resin (2) is different from the resin (1) contained in the pretreatment liquid and the resin contained in the ink. By including resin (2) in the pretreatment liquid, it is possible to improve the adhesion of the ink to a recording medium.

[0190] From the viewpoint of long-term storage stability, the resin (2) is preferably a nonionic resin dispersed by steric hindrance, rather than the commonly used charge-repulsion emulsion. The use of a nonionic resin as the resin (2) is advantageous in that it can solve the following problems: When an anionic resin, which is a charge repulsion type emulsion, is used as the resin (2), aggregation occurs between the inorganic metal salt, which is an example of an aggregating agent, and the anionic resin. When an anionic resin, which is a charge-repulsion type emulsion, is used as the resin (2), the anionic resin instantly aggregates with a metal polyvalent salt that generates trivalent cations upon dissociation. When a cationic resin is used as the resin (2), it is sufficiently stable when left at room temperature, but when it is left standing under heat as an accelerated test for long-term stability, it becomes viscous.

[0191] The nonionic resin is not particularly limited and can be appropriately selected depending on the purpose. For example, polyolefin resin, chlorinated polyolefin resin, polyvinyl acetate resin, polyvinyl chloride resin, polyester resin, polyurethane resin, acrylic resin, styrene-butadiene resin, and copolymers of polymerizable compounds used in the polymerization of these resins can be used. Among these, ethylene-vinyl acetate copolymer resin, ethylene-vinyl acetate-vinyl chloride copolymer resin, ethylene-vinyl acetate-vinyl versatate copolymer, and chlorinated olefin resin are preferred. These resins can further improve the adhesion of the ink to the recording medium. These may be used alone or in combination of two or more.

[0192] The method for determining whether the resin (2) is the nonionic resin is not particularly limited, but examples thereof include a method in which the solid content is isolated from the pretreatment liquid by centrifugation, and then a pyrolysis GC-MS (e.g., GCMS-QP2020NX, manufactured by Shimadzu Corporation) is used to confirm that no material containing acidic functional groups such as carboxyl groups and sulfoxyl groups, or basic functional groups such as amino groups, is detected.

[0193] The shape of the resin (2) is not particularly limited and can be appropriately selected depending on the purpose, and may be regular or irregular. Among these, regular shape is preferable. When the resin (2) has a regular shape, it is preferably spherical. When the resin (2) has a spherical shape, it is preferably in the form of particles.

[0194] The glass transition point (Tg) of the nonionic resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably −30° C. or higher and 30° C. or lower, and more preferably −25° C. or higher and 25° C. or lower. When the glass transition point (Tg) of the nonionic resin is −30° C. or higher, the resin film becomes strong, and the layer formed by the pretreatment liquid becomes more robust. Furthermore, when the glass transition point (Tg) of the nonionic resin is 30° C. or lower, the film-forming properties of the resin are improved and flexibility is ensured, thereby further improving the adhesion of the ink to the recording medium. The glass transition point (Tg) of the nonionic resin can be measured using, for example, a DSC-60A Plus equipped with a cooling device manufactured by Shimadzu Corporation.

[0195] The volume average particle size of the nonionic resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 50 nm or more and 1000 nm or less, and more preferably 100 nm or more and 1000 nm or less. The volume average particle size of the nonionic resin can be measured, for example, by a Nanotrac particle size distribution measuring device (Nnotrac WaveII-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0196] The content (solid content) of the resin (2) is not particularly limited and can be set appropriately depending on the purpose, but is preferably 0.5% by mass or more and 20.0% by mass or less with respect to the total amount of the pretreatment liquid. When the content (solid content) of the resin (2) is 0.5% by mass or more and 20.0% by mass or less with respect to the total amount of the pretreatment liquid, the adhesion of the ink to the recording medium can be further improved.

[0197] <Wax> The wax (2) is not particularly limited and can be appropriately selected depending on the purpose. For example, a water-dispersible wax can be used. Specific examples of the wax include plant- or animal-based waxes such as carnauba wax, candelilla wax, beeswax, rice wax, and lanolin; petroleum-based waxes such as paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, and petrolatum; mineral waxes such as montan wax and ozokerite; and synthetic waxes such as carbon wax, Hoechst wax, polyethylene wax, and stearic acid amide. Among these, paraffin wax and polyethylene wax are preferred, and paraffin wax is more preferred, from the viewpoints of improving the adhesion of the ink to the recording medium and dispersibility in the pretreatment liquid. These may be used alone or in combination of two or more.

[0198] The melting point of the wax is not particularly limited and can be appropriately selected depending on the purpose, but is preferably from 50° C. to 130° C., and more preferably from 60° C. to 120° C. When the melting point of the wax is from 50° C. to 130° C., the adhesion of the ink to the recording medium can be further improved.

[0199] The volume average particle size of the wax is not particularly limited and can be set appropriately depending on the purpose, but is preferably 1 μm or more and 20 μm or less, and more preferably 1 μm or more and 5 μm or less. The volume average particle size of the wax can be measured, for example, by a Nanotrac particle size distribution measuring device (Nanotrac WaveII-UT151, manufactured by Microtrac Bell Co., Ltd.).

[0200] The wax content (solid content) is not particularly limited and can be set appropriately depending on the purpose, but is preferably 0.05% by mass to 5.0% by mass, and more preferably 0.1% by mass to 3.0% by mass, relative to the total amount of the pretreatment liquid. By setting the wax content (solid content) to 0.05% by mass to 5.0% by mass, relative to the total amount of the pretreatment liquid, the white ink can be more easily retained near the surface of the recording medium, thereby improving Hunter whiteness.

[0201] <Organic solvent (2)> In this specification, the organic solvent contained in the pretreatment liquid is sometimes referred to as “organic solvent (2).” Note that this organic solvent (2) is different from the organic solvent contained in the ink. Specific examples of the water-soluble organic solvent (2) include ethylene glycol, propylene glycol, diethylene glycol, 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, and 1,5-pentanediol. polyhydric alcohols such as 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, or pentanetriol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Examples of suitable alkyl ethers include polyhydric alcohol alkyl ethers such as ethylene 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.

[0202] The organic solvent (2) preferably has a boiling point of 250° C. or less, since it not only functions as a wetting agent but also provides good drying properties. Among these, propylene glycol, 1,3-butanediol, and 1,2-butanediol are preferred from the viewpoint of making it easier to wet the surface of the recording medium.

[0203] The content of the organic solvent (2) in the pre-treatment liquid is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of the drying property and ejection reliability of the pre-treatment liquid, the content is preferably 5.0 mass % or more and 60.0 mass % or less, and more preferably 10.0 mass % or more and 30.0 mass % or less, based on the total amount of the pre-treatment liquid.

[0204] <Surfactant (2)> In this specification, the surfactant contained in the pretreatment liquid is sometimes referred to as "surfactant (2)." Note that this surfactant (2) is different from the surfactant contained in the ink. The surfactant (2) is not particularly limited and can be appropriately selected depending on the purpose, and any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used. These can be used alone or in combination of two or more.

[0205] -Silicone surfactants- The silicone surfactant is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable that the surfactant does not decompose even at high pH (pH 11 to 14). Examples of silicone surfactants that do not decompose even at high pH (pH 11 to 14) include side-chain modified polydimethylsiloxanes, both-end modified polydimethylsiloxanes, one-end modified polydimethylsiloxanes, side-chain both-end modified polydimethylsiloxanes, etc. Among these, those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group are preferred from the viewpoints of improving hydrophilicity and increasing solubility in water. The silicone surfactant may also be a polyether-modified silicone surfactant, such as a compound in which a polyalkylene oxide structure is introduced into the Si side chain of dimethylsiloxane.

[0206] The fluorine-based surfactant is not particularly limited and can be appropriately selected depending on the purpose, but the same fluorine-based surfactant as that contained in the ink can be used, and the preferred embodiments are also the same.

[0207] The amphoteric surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.

[0208] The nonionic surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof 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.

[0209] The anionic surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include polyoxyethylene alkyl ether acetates, dodecylbenzenesulfonates, laurates, and polyoxyethylene alkyl ether sulfates.

[0210] <Other ingredients (B)> The other component (B) is not particularly limited as long as it does not impair the effects of the present invention and can be appropriately selected depending on the purpose. Examples include antifoaming agents, antiseptic and antifungal agents, and rust inhibitors.

[0211] -Antifoaming agent- The antifoaming agent can be the same as the antifoaming agent (defoamer) described in the above section <Other Components (A)>. The antifoaming agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include silicone-based antifoaming agents, polyether-based antifoaming agents, and fatty acid ester-based antifoaming agents. Among these, silicone-based antifoaming agents are preferred because of their excellent foam-breaking effect. These may be used alone or in combination of two or more.

[0212] -Preservative and fungicidal agent- As the antiseptic and antifungal agent, the same antiseptic and antifungal agents as those described in the above section <Other Components (A)> can be used.

[0213] -Rust inhibitor- As the rust inhibitor, the same rust inhibitors as those described in the above section <Other Components (A)> can be used.

[0214] From the viewpoint of ensuring that the pretreatment liquid is suitably leveled on the intermediate transfer body and forming a beautiful image, the surface tension of the pretreatment liquid is preferably 22 mN / m or less, and more preferably 21 mN / m or less, in terms of dynamic surface tension at 25°C and a bubble lifetime of 1500 msec, [Example]

[0215] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to these examples. In the following description, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0216] (Preparation of pretreatment liquid) Pretreatment solutions 1 to 8 were prepared by the following method.

[0217] <Preparation Example 1 of Pretreatment Solution: Production of Pretreatment Solution 1> 6.67 parts of cationic surfactant Eutamine 60W (Kao Corporation) were weighed into a glass beaker, and 30.00 parts of high-purity water were added and stirred for 5 minutes. Next, 30.00 parts of propylene glycol, 5.00 parts of 3-methyl-1,3-butanediol, 1.00 parts of Silface SAG503A (Nissin Chemical Industry Co., Ltd.), and 0.50 parts of TEGO Wet 270 (Evonik Japan Co., Ltd.) were added and stirred for 15 minutes. Next, 0.50 parts of a foam inhibitor (2,5,8,11-tetramethyldodecane-5,8-diol), 0.05 parts of a preservative and antifungal agent (PROXEL® GXL), and 0.10 parts of 1,2,3-benzotriazole (Tokyo Chemical Industry Co., Ltd.) were added and mixed and stirred for 15 minutes. High-purity water was then added to make a total of 100 parts, and the mixture was mixed and stirred for 10 minutes. This mixture was filtered under pressure using a polyvinylidene fluoride membrane filter with an average pore size of 5.0 μm to remove insoluble matter and other foreign matter, thereby preparing [Pretreatment liquid 1].

[0218] <Preparation Examples 2 to 8 of Pretreatment Solutions: Production of Pretreatment Solutions 2 to 8> Pre-treatment liquids 2 to 8 were prepared in the same manner as in Pre-treatment liquid Preparation Example 1, except that the ingredients and contents of the pre-treatment liquids were changed to those shown in Table 1 below. In Table 1 below, the units of content of various materials are "mass %", and the content is indicated as total amount, not as solid content or active ingredient amount.

[0219] Details of the various materials shown in Table 1 below are as follows:

[0220] -Inorganic acid salts- Magnesium sulfate heptahydrate: Fujifilm Wako Pure Chemical Industries, Ltd. Calcium nitrate tetrahydrate: Fujifilm Wako Pure Chemical Industries, Ltd.

[0221] -Organic acid salt- Ammonium lactate aqueous solution: 40% active ingredient, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Calcium lactate: Fuso Chemical Co., Ltd.

[0222] -Cationic polymer- Sharol (registered trademark) DC-902P: Polydimethyldiallylammonium chloride, solid content 51.0%, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0223] -Surfactants- Silface SAG503A: Polyether-modified siloxane compound, manufactured by Nissin Chemical Industry Co., Ltd., 100% active ingredient Silface SAG021: Polyether-modified siloxane compound, manufactured by Nissin Chemical Industry Co., Ltd., 100% active ingredient TEGO Wet270: Polyether-modified siloxane compound, manufactured by Evonik Japan Co., Ltd., 100% active ingredient BYK-3451: Polyether-modified siloxane compound, manufactured by BYK Japan Co., Ltd., 100% active ingredient Capstone FS-3100: Partially fluorinated alcohol-substituted glycol compound, manufactured by Chemours, 100% active ingredient Eutamine 60W: Cetyltrimethylammonium chloride (cationic surfactant), manufactured by Kao Corporation, active ingredient 30%

[0224] -Preservative and fungicidal agent- PROXEL® GXL: 1,2-benzothiazolin-3-one as the main ingredient Antiseptic and antifungal agent (manufactured by Avecia, 20% ingredients, contains dipropylene glycol)

[0225] [Table 1]

[0226] (Physical properties of pretreatment liquid) The viscosity, dynamic surface tension, and pH of pretreatment solutions 1 to 8 were measured as follows. The measurement results are shown in Table 2.

[0227] -viscosity- The viscosity of the pretreatment liquid was measured at 25°C using a viscometer (RE85L, manufactured by Toki Sangyo Co., Ltd.).

[0228] -Dynamic surface tension- The dynamic surface tension of the pretreatment liquid at 25° C. was measured using a SITA DynoTester (manufactured by SITA) at a surface life (bubble lifetime) of 1500 msec by the maximum bubble pressure method.

[0229] -pH- The pH of the pretreatment solution was measured at 25°C using a pH meter (HM-30R model, manufactured by DKK-Toa Corporation).

[0230] [Table 2]

[0231] (Water-based ink manufacturing) <Preparation of pigment dispersion or pigment-containing polymer particle dispersion> Pigment dispersions or pigment-containing polymer particle dispersions were prepared by the methods described in Preparation Examples 1 to 8 below.

[0232] <Preparation Example 1: Preparation of surface-modified black pigment dispersion> BLACK PEARLS (registered trademark) 1000 (BET specific surface area 343m 2 A slurry was obtained by mixing 100 g of carbon black (manufactured by Cabot Corporation) having a densitometric average molecular weight of 1 / g and a dibutyl phthalate absorption (DBPA) of 105 mL / 100 g, 100 mmol of sulfanilic acid (manufactured by Hayashi Pure Chemical Industries, Ltd.) and 1 L of highly purified ion-exchanged water at room temperature (23°C ± 0.5°C) using a Silverson (registered trademark) mixer (laboratory mixer, manufactured by Silverson Nippon Co., Ltd.) at 6,000 rpm. Next, 100 mmol of nitric acid (1.42, Honeywell-Fluka) was added to the resulting slurry, and after a further 30 minutes, 100 mmol of sodium nitrite (Hayashi Pure Chemical Industries, Ltd.) dissolved in 10 mL of ion-exchanged high-purity water was slowly added. The mixture was then heated to 60°C with stirring and reacted for 1 hour to obtain a modified pigment in which sulfanilic acid was added to carbon black. Next, the pH was adjusted to 9 with a 10% tetrabutylammonium hydroxide methanol solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and after 30 minutes, a modified pigment dispersion was obtained. Next, this modified pigment dispersion and ion-exchanged high-purity water were subjected to ultrafiltration using a dialysis membrane, and further ultrasonic dispersion was performed to obtain a surface-modified black pigment dispersion containing 20% ​​pigment solids. The surface treatment level of the pigment in the obtained surface-modified black pigment dispersion was 0.75 mmol / g, and when measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.), the cumulative 50% volume particle diameter D50 was 120 nm.

[0233] <Preparation Example 2: Preparation of surface-modified magenta pigment dispersion> 1 kg of pigment dispersion SMART Magenta 3122BA (CI Pigment Red 122 surface-treated dispersion, pigment solid content 14.5%, manufactured by SENSIENT) was acid-precipitated with a 0.1 N hydrochloric acid solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Next, the pH was adjusted to 9 with a 10% aqueous tetraethylammonium hydroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and after 30 minutes, a modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or aminobenzoic acid tetraethylammonium salt was obtained. A modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or aminobenzoic acid tetraethylammonium salt and ion-exchanged highly pure water were subjected to ultrafiltration using a dialysis membrane, and then ultrasonic dispersion was carried out to obtain a surface-modified magenta pigment dispersion containing 20% ​​pigment solids. The surface-modified magenta pigment dispersion thus obtained was measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.), and the cumulative 50% volume particle diameter D50 was found to be 104 nm.

[0234] <Preparation Example 3: Preparation of surface-modified cyan pigment dispersion> 1 kg of pigment dispersion SMART Cyan 3154BA (CI Pigment Blue 15:4 surface-treated dispersion, pigment solid content 14.5%, manufactured by SENSIENT) was acid-precipitated with 0.1 N hydrochloric acid solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Next, the pH was adjusted to 9 with a 40% benzyltrimethylammonium hydroxide methanol solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and after 30 minutes, a modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or aminobenzoic acid benzyltrimethylammonium salt was obtained. The modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or aminobenzoic acid benzyltrimethylammonium salt and ion-exchanged high-purity water were subjected to ultrafiltration using a dialysis membrane, and further ultrasonic dispersion was performed to obtain a surface-modified cyan pigment dispersion containing 20% ​​pigment solids. The resulting surface-modified cyan pigment dispersion was measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.), and the cumulative 50% volume particle diameter D50 was found to be 116 nm.

[0235] <Preparation Example 4: Preparation of surface-modified yellow pigment dispersion> One kilogram of SMART Yellow 3074BA (a surface-treated CI Pigment Yellow 74 dispersion, 14.5% pigment solids, manufactured by Sensient) was adjusted to pH 9 with a 10% tetrabutylammonium hydroxide methanol solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). After 30 minutes, a modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or tetrabutylammonium aminobenzoate was obtained. The modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or tetrabutylammonium aminobenzoate was then subjected to ultrafiltration using a dialysis membrane with ion-exchanged high-purity water, followed by ultrasonic dispersion to obtain a surface-modified yellow pigment dispersion containing 20% ​​pigment solids. The obtained surface-modified yellow pigment dispersion was measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.), and the cumulative 50% volume particle diameter D50 was found to be 145 nm.

[0236] <Preparation Example 5: Preparation of magenta pigment-containing polymer particle dispersion> A 1-L flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas inlet tube, a reflux condenser, and a dropping funnel was thoroughly purged with nitrogen gas, and then 11.2 g of styrene monomer (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 2.8 g of acrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 12.0 g of lauryl methacrylate (manufactured by BASF), 4.0 g of polyethylene glycol dimethacrylate (manufactured by Sigma-Aldrich Japan), 4.0 g of styrene macromer (manufactured by Toagosei Co., Ltd.), and 0.4 g of mercaptoethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed in the flask and the temperature was raised to 65°C. Next, a mixed solution of 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol dimethacrylate, 60.0 g of hydroxyethyl methacrylate (manufactured by Nippon Shokubai Co., Ltd.), 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, 2.4 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (95%, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 18 g of methyl ethyl ketone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise to the flask over 2.5 hours. After the dropwise addition, a mixed solution of 0.8 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (95%, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 18 g of methyl ethyl ketone was added dropwise to the flask over 0.5 hours. After stirring at 65°C for 1 hour, 0.8 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was added and stirred for another 1 hour. After the reaction was completed, 364 g of methyl ethyl ketone was added to the flask, and 800 g of polymer solution A with a concentration of 50% was obtained. Next, 28 g of polymer solution A, 42 g of CI Pigment Red 122 (BASF), 13.6 g of 1 mol / L potassium hydroxide aqueous solution (Fujifilm Wako Pure Chemical Industries, Ltd.), 20 g of methyl ethyl ketone, and 13.6 g of ion-exchanged water were thoroughly stirred and then kneaded using a roll mill. The resulting paste (approximately 117 g) was added to 200 g of pure water and thoroughly stirred. After that, the methyl ethyl ketone and water were distilled off using an evaporator. To remove further coarse particles, this dispersion was pressure-filtered using a polyvinylidene fluoride membrane filter (Sigma-Aldrich Japan) with an average pore size of 5.0 μm to obtain a magenta pigment-containing polymer microparticle dispersion containing 15% pigment solids and 20% total solids. The obtained magenta pigment-containing polymer particle dispersion was measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.), and the cumulative 50% volume particle diameter D50 was found to be 127 nm.

[0237] Preparation Example 6: Preparation of cyan pigment-containing polymer particle dispersion A cyan pigment-containing polymer microparticle dispersion containing 15% pigment solids and 20% total solids was prepared in the same manner as in Preparation Example 5, except that in Preparation Example 5, CI Pigment Red 122 was replaced with a phthalocyanine pigment (CI Pigment Blue 15:3, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.). The polymer particles in the obtained cyan pigment-containing polymer particle dispersion were measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to have a cumulative 50% volume particle diameter D50 of 93 nm.

[0238] <Preparation Example 7: Preparation of yellow pigment-containing polymer particle dispersion> A yellow pigment-containing polymer microparticle dispersion containing 15% pigment solids and 20% total solids was prepared in the same manner as in Preparation Example 5, except that the pigment CI Pigment Red 122 in Preparation Example 5 was changed to a bisazo yellow pigment (CI Pigment Yellow 155, manufactured by DIC Corporation). The polymer particles in the obtained yellow pigment-containing polymer particle dispersion were measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to have a cumulative 50% volume particle diameter D50 of 76 nm.

[0239] Preparation Example 8: Preparation of a dispersion of polymer particles containing black pigment A black pigment-containing polymer microparticle dispersion containing 15% pigment solids and 20% total solids was prepared in the same manner as in Preparation Example 5, except that CI Pigment Red 122 used as the pigment was replaced with carbon black (FW100, manufactured by Degussa). The polymer particles in the obtained black pigment-containing polymer particle dispersion were measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to have a cumulative 50% volume particle diameter D50 of 104 nm.

[0240] (Water-based ink manufacturing) Color inks were produced as aqueous inks by the methods described in the following Water-Based Inks 1 to 9.

[0241] <Production of Water-Based Ink 1> In a container equipped with a stirrer, 0.20 parts of 2-amino-2-ethyl-1,3-propanediol (97%, Fujifilm Wako Pure Chemical Industries, Ltd.), 0.50 parts of 2,4,7,9-tetramethyldecane-4,7-diol, 3.00 parts of 2-ethyl-1,3-hexanediol (Fujifilm Wako Pure Chemical Industries, Ltd.), 30.00 parts of propylene glycol (Fujifilm Wako Pure Chemical Industries, Ltd.), 1.20 parts of TEGO Wet 270 (Evonik Japan Co., Ltd.), and 1.60 parts of Silface SAG503A (Nissin Chemical Industry Co., Ltd.) were added and mixed and stirred for 15 minutes. Next, 0.05 parts of a preservative and antifungal agent (PROXEL® GXL) and 20.00 parts of the surface-modified black pigment dispersion of Preparation Example 1 were added and mixed and stirred for 20 minutes. Next, 22.37 parts of Superflex 460 resin particles and high-purity water in an amount that made the total amount 100 parts were added, and the mixture was mixed and stirred for 15 minutes. The resulting mixture was then pressure filtered through a polyvinylidene fluoride membrane filter with an average pore size of 5.0 μm to remove coarse particles and dust, and water-based ink 1 was obtained.

[0242] <Production of Water-Based Inks 2 to 9> Water-based inks 2 to 9 were obtained in the same manner as in the production example of water-based ink 1, except that the ink formulation was changed to the materials and contents shown in Table 3 below. In Table 3 below, the units of content of various materials are "mass %", and the content is expressed as the total amount, not as the amount of solid content or active ingredient.

[0243] Details of the various materials shown in Table 3 below are as follows:

[0244] -Resin particles- Superflex 460: Polyurethane dispersion, Tg: -21°C, volume average particle size: 40 nm, solid content: 38%, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Superflex 150: Polyurethane dispersion, Tg: 40°C, volume average particle size: 30 nm, solid content: 30%, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. TOCRYL BCX-8111: Acrylic resin emulsion, Tg: -30°C, volume average particle size: 90 nm, solid content: 58%, manufactured by Toyochem Co., Ltd. TOCRYL W-168: Acrylic resin emulsion, Tg: -10°C, volume average particle size: 100 nm, solid content: 49.5%, manufactured by Toyochem Co., Ltd. Hiros PE-1126: Acrylic resin emulsion, Tg: -12°C, volume average particle size: 60nm, solid content: 41.5%, manufactured by Seiko PMC Corporation Hiros JE-1056: Acrylic resin emulsion, Tg: 82°C, volume average particle size: 50 nm, solid content: 42.5%, manufactured by Seiko PMC Corporation Hiros KE-1062: Acrylic resin emulsion, Tg: 96°C, volume average particle size: 80 nm, solid content: 43.0%, manufactured by Seiko PMC Corporation

[0245] -Organic solvents- Propylene glycol (Tokyo Chemical Industry Co., Ltd.) Propylene glycol monopropyl ether (Tokyo Chemical Industry Co., Ltd.) 3-Methyl-1,3-butanediol (Tokyo Chemical Industry Co., Ltd.) 1,2-butanediol (Tokyo Chemical Industry Co., Ltd.) 1,2-Hexanediol (Fujifilm Wako Pure Chemical Industries, Ltd.) 2-Ethyl-1,3-hexanediol (Tokyo Chemical Industry Co., Ltd.)

[0246] -Surfactants- TEGO® Wet 270: Polyether-modified siloxane compound, manufactured by Evonik Japan, 100% active ingredient Silface SAG503A: Polyether-modified siloxane compound, manufactured by Nissin Chemical Industry Co., Ltd., 100% active ingredient Silface SAG021: Polyether-modified siloxane compound, manufactured by Nissin Chemical Industry Co., Ltd., 100% active ingredient Olfine EXP.4200: Acetylene glycol ethylene oxide adduct, manufactured by Nissin Chemical Industry Co., Ltd., 100% active ingredient Unidyne DSN-403N: Perfluoroalkyl polyethylene oxide adduct, manufactured by Daikin Industries, Ltd., active ingredient 75%

[0247] -Preservative and fungicidal agent- PROXEL® GXL: Antiseptic and antifungal agent based on 1,2-benzothiazolin-3-one (manufactured by Avecia, contains 20% dipropylene glycol) -Antifoaming agent- 2,4,7,9-Tetramethyldodecane-4,7-diol 2,5,8,11-tetramethyldodecane-5,8-diol

[0248] - pH adjuster - 2-Amino-2-ethyl-1,3-propanediol (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0249] [Table 3]

[0250] (Water-based ink properties) The viscosity, dynamic surface tension, and pH of the aqueous inks 1 to 9 were measured as follows. The measurement results are shown in Table 4.

[0251] -viscosity- The viscosities of the water-based inks 1 to 9 were measured at 25°C using a viscometer (RE85L, manufactured by Toki Sangyo Co., Ltd.).

[0252] -Dynamic surface tension- The dynamic surface tension of the aqueous ink at 25° C. was measured using a SITA DynoTester (manufactured by SITA) when the surface life (bubble lifetime) was 1500 msec according to the maximum bubble pressure method.

[0253] -pH- The pH of the water-based inks 1 to 9 was measured at 25°C using a pH meter (HM-30R model, manufactured by DKK-Toa Corporation).

[0254] [Table 4]

[0255] (Examples 1 to 14 and Comparative Examples 1 to 5) An image was formed by the method described below. Under environmental conditions adjusted to 23°C ± 0.5°C and 50% ± 5% RH, an inkjet printing device (Garment Printer RICOH Ri 100, manufactured by Ricoh Co., Ltd.) was used, and the driving voltage of the piezoelectric element was varied so that the amount of ink ejected would be uniform, and settings were made so that the same amount of ink would adhere to the ejected object.

[0256] First, the pretreatment liquid was ejected onto a predetermined intermediate transfer body in a predetermined deposition amount using a predetermined ejection method, as shown in Table 5. Subsequently, a predetermined water-based ink (color ink) shown in Table 5 was ejected onto the area where the pretreatment liquid and water-based ink had been applied, in a predetermined deposition amount shown in Table 5. In this manner, the chart shown in FIG. 2 was printed at 600 dpi x 600 dpi.

[0257] Next, the image was dried in an oven (post-drying), and the intermediate transfer body on which the intermediate image was formed was brought into close contact with a predetermined recording medium, followed by thermal transfer using a contact heat fixing device mounted on a RICOH Pro C9500. In this way, an image was formed on the recording medium.

[0258] The details of the intermediate transfer member shown in Table 5 below are as follows: Intermediate transfer body 1: Ethylene propylene rubber sheet (EPDM) 1mm thick, manufactured by Kureha Elastomer Co., Ltd., Part number: EB270NE Intermediate transfer body 2: Silicone rubber, 1 mm thick, manufactured by Kureha Elastomer Co., Ltd., Part number: SW950D Intermediate transfer body 3: Silicone rubber, 1 mm thick, manufactured by Kureha Elastomer Co., Ltd., Part number: SW970D Intermediate transfer body 4: Fluorine rubber, 1 mm thick, manufactured by Kureha Elastomer Co., Ltd., Part number: FB780N

[0259] Details of the various recording media shown in Table 5 below are as follows: Recording medium 1: Printing coated paper (OK top coat + 128g / m 2 (Oji Paper Co., Ltd.) Recording medium 2: Plain printing paper (OK Prince high-quality 64 g / m 2 (Oji Paper Co., Ltd.)

[0260] (evaluation) The images obtained in Examples 1 to 14 and Comparative Examples 1 to 5 were evaluated as follows, and the results are shown in Table 6 below. <Contact angle> 2.0 μL of each ink shown in Table 3 was extruded onto the surface of the intermediate transfer substrate at 25°C from a syringe equipped with a syringe needle having an inner diameter of 0.37 μm and 0.18 mm, and the contact angle 1.5 seconds after dropping was determined by curve fitting. The contact angle (°) at 25°C was measured using an automatic contact angle measuring device DMo-501 (manufactured by Kyowa Interface Science Co., Ltd.).

[0261] <Transfer Density> The transferred solid image area was measured using an X-Rite eXact (manufactured by X-Rite) to measure the density of each area. The evaluation criteria were as follows:

[0262] [Evaluation criteria for printing coated paper] A: Black 2.0 or higher, Cyan 2.0 or higher, Magenta 1.8 or higher, Yellow 1.3 or higher B: Black 1.8 or more and less than 2.0, Cyan 1.8 or more and less than 2.0, Magenta 1.6 or more and less than 1.8, Yellow 1.2 or more and less than 1.3 C: Black 1.6 or more and less than 1.8, Cyan 1.6 or more and less than 1.8, Magenta 1.4 or more and less than 1.6, Yellow 1.1 or more and less than 1.2 D: Black less than 1.6, Cyan less than 1.6, Magenta less than 1.4, Yellow less than 1.1

[0263] [Evaluation criteria for plain printing paper] A: Black 1.6 or higher, Cyan 1.6 or higher, Magenta 1.1 or higher, Yellow 0.9 or higher B: Black 1.4 or more and less than 1.6, Cyan 1.4 or more and less than 1.6, Magenta 1.0 or more and less than 1.1, Yellow 0.85 or more and less than 0.9 C: Black 1.2 or more and less than 1.4, Cyan 1.2 or more and less than 1.4, Magenta 0.9 or more and less than 1.0, Yellow 0.8 or more and less than 0.85 D: Black less than 1.2, Cyan less than 1.2, Magenta less than 0.9, Yellow less than 0.8

[0264] <Sharpness of letters> The characters of the transferred character image were visually evaluated according to the following criteria.

[0265] [Evaluation criteria] A: 4pt characters can be recognized B: 6pt characters can be recognized C: 8pt characters can be recognized D: 8pt text is unclear

[0266] <Beading> The transferred solid image area was observed for beading (uneven density) and evaluated according to the following criteria. [Evaluation criteria] A: No uneven density at all B: Slight unevenness in density C: Uneven density D: Severe unevenness in density

[0267] [Table 5]

[0268] [Table 6]

[0269] In all of the examples and comparative examples, the area of ​​the pretreatment liquid on the intermediate transfer body was set to be larger than the area of ​​the water-based ink on the intermediate transfer body.

[0270] For example, aspects of the present invention are as follows. <1> a pretreatment liquid application step of applying a pretreatment liquid onto the intermediate transfer body; a water-based ink applying step of applying a water-based ink onto the pretreatment liquid applied onto the intermediate transfer body; a drying step of drying the pretreatment liquid and the aqueous ink on the intermediate transfer body; a thermal transfer step of thermally transferring the intermediate image formed on the intermediate transfer body onto a recording medium; Including, An image forming method characterized by satisfying the following conditions (1) to (4): (1) The surface layer of the intermediate transfer member has a Shore A hardness of 80 or less. (2) The contact angle of the intermediate transfer member with respect to the pretreatment liquid is 40° or less after 1.5 seconds of contact with the liquid. (3) The contact angle of the intermediate transfer member with respect to the water-based ink is 40° or less after 1.5 seconds of contact with the ink. (4) The surface tension of the pretreatment liquid and the aqueous ink is 22 mN / m or less when the bubble lifetime is 1500 msec. <2> The surface layer of the intermediate transfer member is made of silicone rubber and fluororubber. <1> The image forming method according to claim 1. <3> The pretreatment liquid contains at least one selected from the group consisting of an inorganic acid salt, an organic acid salt, and a cationic polymer, water, and an organic solvent. <1> or <2> The image forming method according to claim 1. <4> The water-based ink is an ink containing a coloring material, a resin, water, and an organic solvent. <1> ~ <3> 10. The image forming method according to any one of the preceding items. <5> In the thermal transfer step, the thermal transfer is performed at a temperature of 100°C or higher. <1> ~ <4> 10. The image forming method according to any one of the preceding items. <6> the above <1> 1. An ink set comprising a pretreatment liquid and a water-based ink, which is used in the image forming method described in 1., and which satisfies the following requirements (1) to (3): (1) On an intermediate transfer member having a surface layer with a Shore A hardness of 80 or less, the contact angle after 1.5 seconds from the application of a treatment liquid droplet of the pretreatment liquid is 40° or less. (2) On an intermediate transfer member having a surface layer with a Shore A hardness of 80 or less, the contact angle of a water-based ink droplet is 40° or less 1.5 seconds after the ink droplet is dropped onto the intermediate transfer member. (3) The surface tension of the pretreatment liquid and the water-based ink is 22 mN / m or less when the bubble lifetime is 1500 msec. <7> an intermediate transfer member; a pretreatment liquid applying unit that applies a pretreatment liquid onto the intermediate transfer body; a water-based ink applying unit that applies a water-based ink onto the pretreatment liquid applied onto the intermediate transfer body; a drying unit that dries the pretreatment liquid and the aqueous ink on the intermediate transfer body; a thermal transfer means for thermally transferring the intermediate image formed on the intermediate transfer body onto a recording medium; Including, An image forming apparatus characterized by satisfying the following conditions (1) to (4). (1) The surface layer of the intermediate transfer member has a Shore A hardness of 80 or less. (2) The contact angle of the intermediate transfer member with respect to the pretreatment liquid is 40° or less after 1.5 seconds of contact with the liquid. (3) The contact angle of the intermediate transfer member with respect to the water-based ink is 40° or less after 1.5 seconds of contact with the ink. (4) The surface tension of the pretreatment liquid and the aqueous ink is 22 mN / m or less when the bubble lifetime is 1500 msec. [Explanation of symbols]

[0271] 300 Image forming device 301 Intermediate transfer body 302 Pre-treatment liquid discharge device 303K Water-based Ink Discharger (Black) 303C Water-based ink ejection device (Cyan) 303M Water-based ink ejection device (Magenta) 303Y Water-based ink ejection device (Yellow) 305A Drying equipment 305B Drying equipment 306 Heat roller (thermal transfer roller) 307 Cleaning Roller 309A Drive Roller 309C Drive Roller 309B Platen Roller 310 Intermediate Image 311 Recording Media 312 Transcription Image [Prior art documents] [Patent documents]

[0272] [Patent Document 1] Patent No. 4054722

Claims

1. a pretreatment liquid application step of applying a pretreatment liquid onto the intermediate transfer body; a water-based ink applying step of applying a water-based ink onto the pretreatment liquid applied onto the intermediate transfer body; a drying step of drying the pretreatment liquid and the aqueous ink on the intermediate transfer body; a thermal transfer step of thermally transferring the intermediate image formed on the intermediate transfer body onto a recording medium; Including, An image forming method characterized by satisfying the following conditions (1) to (4): (1) The surface layer of the intermediate transfer member has a Shore A hardness of 80 or less. (2) The contact angle of the intermediate transfer member with respect to the pretreatment liquid is 40° or less after 1.5 seconds of contact with the liquid. (3) The contact angle of the intermediate transfer member with respect to the aqueous ink is 40° or less after 1.5 seconds of contact with the ink. (4) The surface tension of the pretreatment liquid and the aqueous ink is 22 mN / m or less at a bubble lifetime of 1500 msec.

2. 2. The image forming method according to claim 1, wherein the surface layer of the intermediate transfer member is made of silicone rubber and fluororubber.

3. 2. The image forming method according to claim 1, wherein the pretreatment liquid comprises at least one selected from the group consisting of an inorganic acid salt, an organic acid salt, and a cationic polymer, water, and an organic solvent.

4. 2. The image forming method according to claim 1, wherein the water-based ink contains a coloring material, a resin, water, and an organic solvent.

5. 2. The image forming method according to claim 1, wherein the thermal transfer is performed at a temperature of 100[deg.] C. or higher in the thermal transfer step.

6. 2. An ink set used in the image forming method according to claim 1, comprising a pretreatment liquid and a water-based ink, the ink set satisfying the following requirements (1) to (3): (1) On an intermediate transfer member having a surface layer with a Shore A hardness of 80 or less, the contact angle of the pretreatment liquid 1.5 seconds after the treatment liquid is dropped onto the intermediate transfer member is 40° or less. (2) On an intermediate transfer member having a surface layer with a Shore A hardness of 80 or less, the contact angle of a water-based ink droplet dropped thereon is 40° or less 1.5 seconds after the ink droplet is dropped. (3) The surface tension of the pretreatment liquid and the aqueous ink is 22 mN / m or less at a bubble lifetime of 1500 msec.

7. an intermediate transfer member; a pretreatment liquid applying unit that applies a pretreatment liquid onto the intermediate transfer body; a water-based ink applying unit that applies a water-based ink onto the pretreatment liquid applied onto the intermediate transfer body; a drying unit that dries the pretreatment liquid and the aqueous ink on the intermediate transfer body; a thermal transfer means for thermally transferring the intermediate image formed on the intermediate transfer body onto a recording medium; Including, An image forming apparatus characterized by satisfying the following conditions (1) to (4): (1) The surface layer of the intermediate transfer member has a Shore A hardness of 80 or less. (2) The contact angle of the intermediate transfer member with respect to the pretreatment liquid is 40° or less after 1.5 seconds of contact with the liquid. (3) The contact angle of the intermediate transfer member with respect to the aqueous ink is 40° or less after 1.5 seconds of contact with the ink. (4) The surface tension of the pretreatment liquid and the aqueous ink is 22 mN / m or less at a bubble lifetime of 1500 msec.

Images